map is the pointer of outer map, and need_defer needs some explanation.
need_defer tells the implementation to defer the reference release of
the passed element and ensure that the element is still alive before
the bpf program, which may manipulate it, exits.
The following three cases will invoke map_fd_put_ptr() and different
need_defer values will be passed to these callers:
1) release the reference of the old element in the map during map update
or map deletion. The release must be deferred, otherwise the bpf
program may incur use-after-free problem, so need_defer needs to be
true.
2) release the reference of the to-be-added element in the error path of
map update. The to-be-added element is not visible to any bpf
program, so it is OK to pass false for need_defer parameter.
3) release the references of all elements in the map during map release.
Any bpf program which has access to the map must have been exited and
released, so need_defer=false will be OK.
These two parameters will be used by the following patches to fix the
potential use-after-free problem for map-in-map.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231204140425.1480317-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Emit tnum representation as just a constant if all bits are known.
Use decimal-vs-hex logic to determine exact format of emitted
constant value, just like it's done for register range values.
For that move tnum_strn() to kernel/bpf/log.c to reuse decimal-vs-hex
determination logic and constants.
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-12-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Given we enforce a valid range for program and async callback return
value, we must mark R0 as precise to avoid incorrect state pruning.
Fixes: b5dc0163d8 ("bpf: precise scalar_value tracking")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Use common logic to verify program return values and async callback
return values. This allows to avoid duplication of any extra steps
necessary, like precision marking, which will be added in the next
patch.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-8-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Similarly to subprog/callback logic, enforce return value of BPF program
using more precise smin/smax range.
We need to adjust a bunch of tests due to a changed format of an error
message.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Instead of relying on potentially imprecise tnum representation of
expected return value range for callbacks and subprogs, validate that
smin/smax range satisfy exact expected range of return values.
E.g., if callback would need to return [0, 2] range, tnum can't
represent this precisely and instead will allow [0, 3] range. By
checking smin/smax range, we can make sure that subprog/callback indeed
returns only valid [0, 2] range.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Given verifier checks actual value, r0 has to be precise, so we need to
propagate precision properly. r0 also has to be marked as read,
otherwise subsequent state comparisons will ignore such register as
unimportant and precision won't really help here.
Fixes: 69c087ba62 ("bpf: Add bpf_for_each_map_elem() helper")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Bpf cpu=v4 support is introduced in [1] and Commit 4cd58e9af8
("bpf: Support new 32bit offset jmp instruction") added support for new
32bit offset jmp instruction. Unfortunately, in function
bpf_adj_delta_to_off(), for new branch insn with 32bit offset, the offset
(plus/minor a small delta) compares to 16-bit offset bound
[S16_MIN, S16_MAX], which caused the following verification failure:
$ ./test_progs-cpuv4 -t verif_scale_pyperf180
...
insn 10 cannot be patched due to 16-bit range
...
libbpf: failed to load object 'pyperf180.bpf.o'
scale_test:FAIL:expect_success unexpected error: -12 (errno 12)
#405 verif_scale_pyperf180:FAIL
Note that due to recent llvm18 development, the patch [2] (already applied
in bpf-next) needs to be applied to bpf tree for testing purpose.
The fix is rather simple. For 32bit offset branch insn, the adjusted
offset compares to [S32_MIN, S32_MAX] and then verification succeeded.
[1] https://lore.kernel.org/all/20230728011143.3710005-1-yonghong.song@linux.dev
[2] https://lore.kernel.org/bpf/20231110193644.3130906-1-yonghong.song@linux.dev
Fixes: 4cd58e9af8 ("bpf: Support new 32bit offset jmp instruction")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231201024640.3417057-1-yonghong.song@linux.dev
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2023-11-30
We've added 30 non-merge commits during the last 7 day(s) which contain
a total of 58 files changed, 1598 insertions(+), 154 deletions(-).
The main changes are:
1) Add initial TX metadata implementation for AF_XDP with support in mlx5
and stmmac drivers. Two types of offloads are supported right now, that
is, TX timestamp and TX checksum offload, from Stanislav Fomichev with
stmmac implementation from Song Yoong Siang.
2) Change BPF verifier logic to validate global subprograms lazily instead
of unconditionally before the main program, so they can be guarded using
BPF CO-RE techniques, from Andrii Nakryiko.
3) Add BPF link_info support for uprobe multi link along with bpftool
integration for the latter, from Jiri Olsa.
4) Use pkg-config in BPF selftests to determine ld flags which is
in particular needed for linking statically, from Akihiko Odaki.
5) Fix a few BPF selftest failures to adapt to the upcoming LLVM18,
from Yonghong Song.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (30 commits)
bpf/tests: Remove duplicate JSGT tests
selftests/bpf: Add TX side to xdp_hw_metadata
selftests/bpf: Convert xdp_hw_metadata to XDP_USE_NEED_WAKEUP
selftests/bpf: Add TX side to xdp_metadata
selftests/bpf: Add csum helpers
selftests/xsk: Support tx_metadata_len
xsk: Add option to calculate TX checksum in SW
xsk: Validate xsk_tx_metadata flags
xsk: Document tx_metadata_len layout
net: stmmac: Add Tx HWTS support to XDP ZC
net/mlx5e: Implement AF_XDP TX timestamp and checksum offload
tools: ynl: Print xsk-features from the sample
xsk: Add TX timestamp and TX checksum offload support
xsk: Support tx_metadata_len
selftests/bpf: Use pkg-config for libelf
selftests/bpf: Override PKG_CONFIG for static builds
selftests/bpf: Choose pkg-config for the target
bpftool: Add support to display uprobe_multi links
selftests/bpf: Add link_info test for uprobe_multi link
selftests/bpf: Use bpf_link__destroy in fill_link_info tests
...
====================
Conflicts:
Documentation/netlink/specs/netdev.yaml:
839ff60df3 ("net: page_pool: add nlspec for basic access to page pools")
48eb03dd26 ("xsk: Add TX timestamp and TX checksum offload support")
https://lore.kernel.org/all/20231201094705.1ee3cab8@canb.auug.org.au/
While at it also regen, tree is dirty after:
48eb03dd26 ("xsk: Add TX timestamp and TX checksum offload support")
looks like code wasn't re-rendered after "render-max" was removed.
Link: https://lore.kernel.org/r/20231130145708.32573-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
bpf_mem_cache_alloc_flags() may call __alloc() directly when there is no
free object in free list, but it doesn't initialize the allocation hint
for the returned pointer. It may lead to bad memory dereference when
freeing the pointer, so fix it by initializing the allocation hint.
Fixes: 822fb26bdb ("bpf: Add a hint to allocated objects.")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231111043821.2258513-1-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Slightly change BPF verifier logic around eagerness and order of global
subprog validation. Instead of going over every global subprog eagerly
and validating it before main (entry) BPF program is verified, turn it
around. Validate main program first, mark subprogs that were called from
main program for later verification, but otherwise assume it is valid.
Afterwards, go over marked global subprogs and validate those,
potentially marking some more global functions as being called. Continue
this process until all (transitively) callable global subprogs are
validated. It's a BFS traversal at its heart and will always converge.
This is an important change because it allows to feature-gate some
subprograms that might not be verifiable on some older kernel, depending
on supported set of features.
E.g., at some point, global functions were allowed to accept a pointer
to memory, which size is identified by user-provided type.
Unfortunately, older kernels don't support this feature. With BPF CO-RE
approach, the natural way would be to still compile BPF object file once
and guard calls to this global subprog with some CO-RE check or using
.rodata variables. That's what people do to guard usage of new helpers
or kfuncs, and any other new BPF-side feature that might be missing on
old kernels.
That's currently impossible to do with global subprogs, unfortunately,
because they are eagerly and unconditionally validated. This patch set
aims to change this, so that in the future when global funcs gain new
features, those can be guarded using BPF CO-RE techniques in the same
fashion as any other new kernel feature.
Two selftests had to be adjusted in sync with these changes.
test_global_func12 relied on eager global subprog validation failing
before main program failure is detected (unknown return value). Fix by
making sure that main program is always valid.
verifier_subprog_precision's parent_stack_slot_precise subtest relied on
verifier checkpointing heuristic to do a checkpoint at instruction #5,
but that's no longer true because we don't have enough jumps validated
before reaching insn #5 due to global subprogs being validated later.
Other than that, no changes, as one would expect.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231124035937.403208-3-andrii@kernel.org
We have the name, instead of emitting just func#N to identify global
subprog, augment verifier log messages with actual function name to make
it more user-friendly.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231124035937.403208-2-andrii@kernel.org
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2023-11-21
We've added 85 non-merge commits during the last 12 day(s) which contain
a total of 63 files changed, 4464 insertions(+), 1484 deletions(-).
The main changes are:
1) Huge batch of verifier changes to improve BPF register bounds logic
and range support along with a large test suite, and verifier log
improvements, all from Andrii Nakryiko.
2) Add a new kfunc which acquires the associated cgroup of a task within
a specific cgroup v1 hierarchy where the latter is identified by its id,
from Yafang Shao.
3) Extend verifier to allow bpf_refcount_acquire() of a map value field
obtained via direct load which is a use-case needed in sched_ext,
from Dave Marchevsky.
4) Fix bpf_get_task_stack() helper to add the correct crosstask check
for the get_perf_callchain(), from Jordan Rome.
5) Fix BPF task_iter internals where lockless usage of next_thread()
was wrong. The rework also simplifies the code, from Oleg Nesterov.
6) Fix uninitialized tail padding via LIBBPF_OPTS_RESET, and another
fix for certain BPF UAPI structs to fix verifier failures seen
in bpf_dynptr usage, from Yonghong Song.
7) Add BPF selftest fixes for map_percpu_stats flakes due to per-CPU BPF
memory allocator not being able to allocate per-CPU pointer successfully,
from Hou Tao.
8) Add prep work around dynptr and string handling for kfuncs which
is later going to be used by file verification via BPF LSM and fsverity,
from Song Liu.
9) Improve BPF selftests to update multiple prog_tests to use ASSERT_*
macros, from Yuran Pereira.
10) Optimize LPM trie lookup to check prefixlen before walking the trie,
from Florian Lehner.
11) Consolidate virtio/9p configs from BPF selftests in config.vm file
given they are needed consistently across archs, from Manu Bretelle.
12) Small BPF verifier refactor to remove register_is_const(),
from Shung-Hsi Yu.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (85 commits)
selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in vmlinux
selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in bpf_obj_id
selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in bind_perm
selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in bpf_tcp_ca
selftests/bpf: reduce verboseness of reg_bounds selftest logs
bpf: bpf_iter_task_next: use next_task(kit->task) rather than next_task(kit->pos)
bpf: bpf_iter_task_next: use __next_thread() rather than next_thread()
bpf: task_group_seq_get_next: use __next_thread() rather than next_thread()
bpf: emit frameno for PTR_TO_STACK regs if it differs from current one
bpf: smarter verifier log number printing logic
bpf: omit default off=0 and imm=0 in register state log
bpf: emit map name in register state if applicable and available
bpf: print spilled register state in stack slot
bpf: extract register state printing
bpf: move verifier state printing code to kernel/bpf/log.c
bpf: move verbose_linfo() into kernel/bpf/log.c
bpf: rename BPF_F_TEST_SANITY_STRICT to BPF_F_TEST_REG_INVARIANTS
bpf: Remove test for MOVSX32 with offset=32
selftests/bpf: add iter test requiring range x range logic
veristat: add ability to set BPF_F_TEST_SANITY_STRICT flag with -r flag
...
====================
Link: https://lore.kernel.org/r/20231122000500.28126-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In some cases verifier can't infer convergence of the bpf_loop()
iteration. E.g. for the following program:
static int cb(__u32 idx, struct num_context* ctx)
{
ctx->i++;
return 0;
}
SEC("?raw_tp")
int prog(void *_)
{
struct num_context ctx = { .i = 0 };
__u8 choice_arr[2] = { 0, 1 };
bpf_loop(2, cb, &ctx, 0);
return choice_arr[ctx.i];
}
Each 'cb' simulation would eventually return to 'prog' and reach
'return choice_arr[ctx.i]' statement. At which point ctx.i would be
marked precise, thus forcing verifier to track multitude of separate
states with {.i=0}, {.i=1}, ... at bpf_loop() callback entry.
This commit allows "brute force" handling for such cases by limiting
number of callback body simulations using 'umax' value of the first
bpf_loop() parameter.
For this, extend bpf_func_state with 'callback_depth' field.
Increment this field when callback visiting state is pushed to states
traversal stack. For frame #N it's 'callback_depth' field counts how
many times callback with frame depth N+1 had been executed.
Use bpf_func_state specifically to allow independent tracking of
callback depths when multiple nested bpf_loop() calls are present.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231121020701.26440-11-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Callbacks are similar to open coded iterators, so add imprecise
widening logic for callback body processing. This makes callback based
loops behave identically to open coded iterators, e.g. allowing to
verify programs like below:
struct ctx { u32 i; };
int cb(u32 idx, struct ctx* ctx)
{
++ctx->i;
return 0;
}
...
struct ctx ctx = { .i = 0 };
bpf_loop(100, cb, &ctx, 0);
...
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231121020701.26440-9-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Prior to this patch callbacks were handled as regular function calls,
execution of callback body was modeled exactly once.
This patch updates callbacks handling logic as follows:
- introduces a function push_callback_call() that schedules callback
body verification in env->head stack;
- updates prepare_func_exit() to reschedule callback body verification
upon BPF_EXIT;
- as calls to bpf_*_iter_next(), calls to callback invoking functions
are marked as checkpoints;
- is_state_visited() is updated to stop callback based iteration when
some identical parent state is found.
Paths with callback function invoked zero times are now verified first,
which leads to necessity to modify some selftests:
- the following negative tests required adding release/unlock/drop
calls to avoid previously masked unrelated error reports:
- cb_refs.c:underflow_prog
- exceptions_fail.c:reject_rbtree_add_throw
- exceptions_fail.c:reject_with_cp_reference
- the following precision tracking selftests needed change in expected
log trace:
- verifier_subprog_precision.c:callback_result_precise
(note: r0 precision is no longer propagated inside callback and
I think this is a correct behavior)
- verifier_subprog_precision.c:parent_callee_saved_reg_precise_with_callback
- verifier_subprog_precision.c:parent_stack_slot_precise_with_callback
Reported-by: Andrew Werner <awerner32@gmail.com>
Closes: https://lore.kernel.org/bpf/CA+vRuzPChFNXmouzGG+wsy=6eMcfr1mFG0F3g7rbg-sedGKW3w@mail.gmail.com/
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231121020701.26440-7-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move code for simulated stack frame creation to a separate utility
function. This function would be used in the follow-up change for
callbacks handling.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231121020701.26440-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Split check_reg_arg() into two utility functions:
- check_reg_arg() operating on registers from current verifier state;
- __check_reg_arg() operating on a specific set of registers passed as
a parameter;
The __check_reg_arg() function would be used by a follow-up change for
callbacks handling.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231121020701.26440-5-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This looks more clear and simplifies the code. While at it, remove the
unnecessary initialization of pos/task at the start of bpf_iter_task_new().
Note that we can even kill kit->task, we can just use pos->group_leader,
but I don't understand the BUILD_BUG_ON() checks in bpf_iter_task_new().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231114163239.GA903@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c
is the last user and the usage is wrong.
bpf_iter_task_next() can loop forever, "kit->pos == kit->task" can never
happen if kit->pos execs. Change this code to use __next_thread().
With or without this change the usage of kit->pos/task and next_task()
doesn't look nice, see the next patch.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231114163237.GA897@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c
is the last user and the usage is wrong.
task_group_seq_get_next() can return the group leader twice if it races
with mt-thread exec which changes the group->leader's pid.
Change the main loop to use __next_thread(), kill "next_tid == common->pid"
check.
__next_thread() can't loop forever, we can also change this code to retry
if next_tid == 0.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231114163234.GA890@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
It's possible to pass a pointer to parent's stack to child subprogs. In
such case verifier state output is ambiguous not showing whether
register container a pointer to "current" stack, belonging to current
subprog (frame), or it's actually a pointer to one of parent frames.
So emit this information if frame number differs between the state which
register is part of. E.g., if current state is in frame 2 and it has
a register pointing to stack in grand parent state (frame #0), we'll see
something like 'R1=fp[0]-16', while "local stack pointer" will be just
'R2=fp-16'.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Instead of always printing numbers as either decimals (and in some
cases, like for "imm=%llx", in hexadecimals), decide the form based on
actual values. For numbers in a reasonably small range (currently,
[0, U16_MAX] for unsigned values, and [S16_MIN, S16_MAX] for signed ones),
emit them as decimals. In all other cases, even for signed values,
emit them in hexadecimals.
For large values hex form is often times way more useful: it's easier to
see an exact difference between 0xffffffff80000000 and 0xffffffff7fffffff,
than between 18446744071562067966 and 18446744071562067967, as one
particular example.
Small values representing small pointer offsets or application
constants, on the other hand, are way more useful to be represented in
decimal notation.
Adjust reg_bounds register state parsing logic to take into account this
change.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-8-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Simplify BPF verifier log further by omitting default (and frequently
irrelevant) off=0 and imm=0 parts for non-SCALAR_VALUE registers. As can
be seen from fixed tests, this is often a visual noise for PTR_TO_CTX
register and even for PTR_TO_PACKET registers.
Omitting default values follows the rest of register state logic: we
omit default values to keep verifier log succinct and to highlight
interesting state that deviates from default one. E.g., we do the same
for var_off, when it's unknown, which gives no additional information.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In complicated real-world applications, whenever debugging some
verification error through verifier log, it often would be very useful
to see map name for PTR_TO_MAP_VALUE register. Usually this needs to be
inferred from key/value sizes and maybe trying to guess C code location,
but it's not always clear.
Given verifier has the name, and it's never too long, let's just emit it
for ptr_to_map_key, ptr_to_map_value, and const_ptr_to_map registers. We
reshuffle the order a bit, so that map name, key size, and value size
appear before offset and immediate values, which seems like a more
logical order.
Current output:
R1_w=map_ptr(map=array_map,ks=4,vs=8,off=0,imm=0)
But we'll get rid of useless off=0 and imm=0 parts in the next patch.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Print the same register state representation when printing stack state,
as we do for normal registers. Note that if stack slot contains
subregister spill (1, 2, or 4 byte long), we'll still emit "m0?" mask
for those bytes that are not part of spilled register.
While means we can get something like fp-8=0000scalar() for a 4-byte
spill with other 4 bytes still being STACK_ZERO.
Some example before and after, taken from the log of
pyperf_subprogs.bpf.o:
49: (7b) *(u64 *)(r10 -256) = r1 ; frame1: R1_w=ctx(off=0,imm=0) R10=fp0 fp-256_w=ctx
49: (7b) *(u64 *)(r10 -256) = r1 ; frame1: R1_w=ctx(off=0,imm=0) R10=fp0 fp-256_w=ctx(off=0,imm=0)
150: (7b) *(u64 *)(r10 -264) = r0 ; frame1: R0_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) R10=fp0 fp-264_w=map_value_or_null
150: (7b) *(u64 *)(r10 -264) = r0 ; frame1: R0_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) R10=fp0 fp-264_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0)
5192: (61) r1 = *(u32 *)(r10 -272) ; frame1: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) R10=fp0 fp-272=
5192: (61) r1 = *(u32 *)(r10 -272) ; frame1: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) R10=fp0 fp-272=????scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf))
While at it, do a few other simple clean ups:
- skip slot if it's not scratched before detecting whether it's valid;
- move taking spilled_reg pointer outside of switch (only DYNPTR has
to adjust that to get to the "main" slot);
- don't recalculate types_buf second time for MISC/ZERO/default case.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Extract printing register state representation logic into a separate
helper, as we are going to reuse it for spilled register state printing
in the next patch. This also nicely reduces code nestedness.
No functional changes.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move a good chunk of code from verifier.c to log.c: verifier state
verbose printing logic. This is an important and very much
logging/debugging oriented code. It fits the overlall log.c's focus on
verifier logging, and moving it allows to keep growing it without
unnecessarily adding to verifier.c code that otherwise contains a core
verification logic.
There are not many shared dependencies between this code and the rest of
verifier.c code, except a few single-line helpers for various register
type checks and a bit of state "scratching" helpers. We move all such
trivial helpers into include/bpf/bpf_verifier.h as static inlines.
No functional changes in this patch.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
verifier.c is huge. Let's try to move out parts that are logging-related
into log.c, as we previously did with bpf_log() and other related stuff.
This patch moves line info verbose output routines: it's pretty
self-contained and isolated code, so there is no problem with this.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This change doesn't seem to have any effect on selftests and production
BPF object files, but we preemptively try to make it more robust.
First, "learn sign from signed bounds" comment is misleading, as we are
learning not just sign, but also values.
Second, we simplify the check for determining whether entire range is
positive or negative similarly to other checks added earlier, using
appropriate u32/u64 cast and single comparisons. As explain in comments
in __reg64_deduce_bounds(), the checks are equivalent.
Last but not least, smin/smax and s32_min/s32_max reassignment based on
min/max of both umin/umax and smin/smax (and 32-bit equivalents) is hard
to explain and justify. We are updating unsigned bounds from signed
bounds, why would we update signed bounds at the same time? This might
be correct, but it's far from obvious why and the code or comments don't
try to justify this. Given we've added a separate deduction of signed
bounds from unsigned bounds earlier, this seems at least redundant, if
not just wrong.
In short, we remove doubtful pieces, and streamline the rest to follow
the logic and approach of the rest of reg_bounds_sync() checks.
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231112010609.848406-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Equivalent checks were recently added in more succinct and, arguably,
safer form in:
- f188765f23a5 ("bpf: derive smin32/smax32 from umin32/umax32 bounds");
- 2e74aef782d3 ("bpf: derive smin/smax from umin/max bounds").
The checks we are removing in this patch set do similar checks to detect
if entire u32/u64 range has signed bit set or not set, but does it with
two separate checks.
Further, we forcefully overwrite either smin or smax (and 32-bit equvalents)
without applying normal min/max intersection logic. It's not clear why
that would be correct in all cases and seems to work by accident. This
logic is also "gated" by previous signed -> unsigned derivation, which
returns early.
All this is quite confusing and seems error-prone, while we already have
at least equivalent checks happening earlier. So remove this duplicate
and error-prone logic to simplify things a bit.
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231112010609.848406-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add simple sanity checks that validate well-formed ranges (min <= max)
across u64, s64, u32, and s32 ranges. Also for cases when the value is
constant (either 64-bit or 32-bit), we validate that ranges and tnums
are in agreement.
These bounds checks are performed at the end of BPF_ALU/BPF_ALU64
operations, on conditional jumps, and for LDX instructions (where subreg
zero/sign extension is probably the most important to check). This
covers most of the interesting cases.
Also, we validate the sanity of the return register when manually
adjusting it for some special helpers.
By default, sanity violation will trigger a warning in verifier log and
resetting register bounds to "unbounded" ones. But to aid development
and debugging, BPF_F_TEST_SANITY_STRICT flag is added, which will
trigger hard failure of verification with -EFAULT on register bounds
violations. This allows selftests to catch such issues. veristat will
also gain a CLI option to enable this behavior.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231112010609.848406-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Use 32-bit subranges to prune some 64-bit BPF_JEQ/BPF_JNE conditions
that otherwise would be "inconclusive" (i.e., is_branch_taken() would
return -1). This can happen, for example, when registers are initialized
as 64-bit u64/s64, then compared for inequality as 32-bit subregisters,
and then followed by 64-bit equality/inequality check. That 32-bit
inequality can establish some pattern for lower 32 bits of a register
(e.g., s< 0 condition determines whether the bit #31 is zero or not),
while overall 64-bit value could be anything (according to a value range
representation).
This is not a fancy quirky special case, but actually a handling that's
necessary to prevent correctness issue with BPF verifier's range
tracking: set_range_min_max() assumes that register ranges are
non-overlapping, and if that condition is not guaranteed by
is_branch_taken() we can end up with invalid ranges, where min > max.
[0] https://lore.kernel.org/bpf/CACkBjsY2q1_fUohD7hRmKGqv1MV=eP2f6XK8kjkYNw7BaiF8iQ@mail.gmail.com/
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231112010609.848406-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Generalize is_branch_taken logic for SCALAR_VALUE register to handle
cases when both registers are not constants. Previously supported
<range> vs <scalar> cases are a natural subset of more generic <range>
vs <range> set of cases.
Generalized logic relies on straightforward segment intersection checks.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231112010609.848406-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Generalize bounds adjustment logic of reg_set_min_max() to handle not
just register vs constant case, but in general any register vs any
register cases. For most of the operations it's trivial extension based
on range vs range comparison logic, we just need to properly pick
min/max of a range to compare against min/max of the other range.
For BPF_JSET we keep the original capabilities, just make sure JSET is
integrated in the common framework. This is manifested in the
internal-only BPF_JSET + BPF_X "opcode" to allow for simpler and more
uniform rev_opcode() handling. See the code for details. This allows to
reuse the same code exactly both for TRUE and FALSE branches without
explicitly handling both conditions with custom code.
Note also that now we don't need a special handling of BPF_JEQ/BPF_JNE
case none of the registers are constants. This is now just a normal
generic case handled by reg_set_min_max().
To make tnum handling cleaner, tnum_with_subreg() helper is added, as
that's a common operator when dealing with 32-bit subregister bounds.
This keeps the overall logic much less noisy when it comes to tnums.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231112010609.848406-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Kirill Shutemov reported significant percpu memory consumption increase after
booting in 288-cpu VM ([1]) due to commit 41a5db8d81 ("bpf: Add support for
non-fix-size percpu mem allocation"). The percpu memory consumption is
increased from 111MB to 969MB. The number is from /proc/meminfo.
I tried to reproduce the issue with my local VM which at most supports upto
255 cpus. With 252 cpus, without the above commit, the percpu memory
consumption immediately after boot is 57MB while with the above commit the
percpu memory consumption is 231MB.
This is not good since so far percpu memory from bpf memory allocator is not
widely used yet. Let us change pre-allocation in init stage to on-demand
allocation when verifier detects there is a need of percpu memory for bpf
program. With this change, percpu memory consumption after boot can be reduced
signicantly.
[1] https://lore.kernel.org/lkml/20231109154934.4saimljtqx625l3v@box.shutemov.name/
Fixes: 41a5db8d81 ("bpf: Add support for non-fix-size percpu mem allocation")
Reported-and-tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231111013928.948838-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A new kfunc is added to acquire cgroup1 of a task:
- bpf_task_get_cgroup1
Acquires the associated cgroup of a task whithin a specific cgroup1
hierarchy. The cgroup1 hierarchy is identified by its hierarchy ID.
This new kfunc enables the tracing of tasks within a designated
container or cgroup directory in BPF programs.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20231111090034.4248-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently get_perf_callchain only supports user stack walking for
the current task. Passing the correct *crosstask* param will return
0 frames if the task passed to __bpf_get_stack isn't the current
one instead of a single incorrect frame/address. This change
passes the correct *crosstask* param but also does a preemptive
check in __bpf_get_stack if the task is current and returns
-EOPNOTSUPP if it is not.
This issue was found using bpf_get_task_stack inside a BPF
iterator ("iter/task"), which iterates over all tasks.
bpf_get_task_stack works fine for fetching kernel stacks
but because get_perf_callchain relies on the caller to know
if the requested *task* is the current one (via *crosstask*)
it was failing in a confusing way.
It might be possible to get user stacks for all tasks utilizing
something like access_process_vm but that requires the bpf
program calling bpf_get_task_stack to be sleepable and would
therefore be a breaking change.
Fixes: fa28dcb82a ("bpf: Introduce helper bpf_get_task_stack()")
Signed-off-by: Jordan Rome <jordalgo@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231108112334.3433136-1-jordalgo@meta.com
When BPF program is verified in privileged mode, BPF verifier allows
bounded loops. This means that from CFG point of view there are
definitely some back-edges. Original commit adjusted check_cfg() logic
to not detect back-edges in control flow graph if they are resulting
from conditional jumps, which the idea that subsequent full BPF
verification process will determine whether such loops are bounded or
not, and either accept or reject the BPF program. At least that's my
reading of the intent.
Unfortunately, the implementation of this idea doesn't work correctly in
all possible situations. Conditional jump might not result in immediate
back-edge, but just a few unconditional instructions later we can arrive
at back-edge. In such situations check_cfg() would reject BPF program
even in privileged mode, despite it might be bounded loop. Next patch
adds one simple program demonstrating such scenario.
To keep things simple, instead of trying to detect back edges in
privileged mode, just assume every back edge is valid and let subsequent
BPF verification prove or reject bounded loops.
Note a few test changes. For unknown reason, we have a few tests that
are specified to detect a back-edge in a privileged mode, but looking at
their code it seems like the right outcome is passing check_cfg() and
letting subsequent verification to make a decision about bounded or not
bounded looping.
Bounded recursion case is also interesting. The example should pass, as
recursion is limited to just a few levels and so we never reach maximum
number of nested frames and never exhaust maximum stack depth. But the
way that max stack depth logic works today it falsely detects this as
exceeding max nested frame count. This patch series doesn't attempt to
fix this orthogonal problem, so we just adjust expected verifier failure.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Fixes: 2589726d12 ("bpf: introduce bounded loops")
Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231110061412.2995786-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Fix an edge case in __mark_chain_precision() which prematurely stops
backtracking instructions in a state if it happens that state's first
and last instruction indexes are the same. This situations doesn't
necessarily mean that there were no instructions simulated in a state,
but rather that we starting from the instruction, jumped around a bit,
and then ended up at the same instruction before checkpointing or
marking precision.
To distinguish between these two possible situations, we need to consult
jump history. If it's empty or contain a single record "bridging" parent
state and first instruction of processed state, then we indeed
backtracked all instructions in this state. But if history is not empty,
we are definitely not done yet.
Move this logic inside get_prev_insn_idx() to contain it more nicely.
Use -ENOENT return code to denote "we are out of instructions"
situation.
This bug was exposed by verifier_loop1.c's bounded_recursion subtest, once
the next fix in this patch set is applied.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Fixes: b5dc0163d8 ("bpf: precise scalar_value tracking")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231110002638.4168352-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
ldimm64 instructions are 16-byte long, and so have to be handled
appropriately in check_cfg(), just like the rest of BPF verifier does.
This has implications in three places:
- when determining next instruction for non-jump instructions;
- when determining next instruction for callback address ldimm64
instructions (in visit_func_call_insn());
- when checking for unreachable instructions, where second half of
ldimm64 is expected to be unreachable;
We take this also as an opportunity to report jump into the middle of
ldimm64. And adjust few test_verifier tests accordingly.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Reported-by: Hao Sun <sunhao.th@gmail.com>
Fixes: 475fb78fbf ("bpf: verifier (add branch/goto checks)")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231110002638.4168352-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch enables the following pattern:
/* mapval contains a __kptr pointing to refcounted local kptr */
mapval = bpf_map_lookup_elem(&map, &idx);
if (!mapval || !mapval->some_kptr) { /* omitted */ }
p = bpf_refcount_acquire(&mapval->some_kptr);
Currently this doesn't work because bpf_refcount_acquire expects an
owning or non-owning ref. The verifier defines non-owning ref as a type:
PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF
while mapval->some_kptr is PTR_TO_BTF_ID | PTR_UNTRUSTED. It's possible
to do the refcount_acquire by first bpf_kptr_xchg'ing mapval->some_kptr
into a temp kptr, refcount_acquiring that, and xchg'ing back into
mapval, but this is unwieldy and shouldn't be necessary.
This patch modifies btf_ld_kptr_type such that user-allocated types are
marked MEM_ALLOC and if those types have a bpf_{rb,list}_node they're
marked NON_OWN_REF as well. Additionally, due to changes to
bpf_obj_drop_impl earlier in this series, rcu_protected_object now
returns true for all user-allocated types, resulting in
mapval->some_kptr being marked MEM_RCU.
After this patch's changes, mapval->some_kptr is now:
PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU
which results in it passing the non-owning ref test, and the motivating
example passing verification.
Future work will likely get rid of special non-owning ref lifetime logic
in the verifier, at which point we'll be able to delete the NON_OWN_REF
flag entirely.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20231107085639.3016113-6-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This refactoring patch removes the unused BPF_GRAPH_NODE_OR_ROOT
btf_field_type and moves BPF_GRAPH_{NODE,ROOT} macros into the
btf_field_type enum. Further patches in the series will use
BPF_GRAPH_NODE, so let's move this useful definition out of btf.c.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20231107085639.3016113-5-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The use of bpf_mem_free_rcu to free refcounted local kptrs was added
in commit 7e26cd12ad ("bpf: Use bpf_mem_free_rcu when
bpf_obj_dropping refcounted nodes"). In the cover letter for the
series containing that patch [0] I commented:
Perhaps it makes sense to move to mem_free_rcu for _all_
non-owning refs in the future, not just refcounted. This might
allow custom non-owning ref lifetime + invalidation logic to be
entirely subsumed by MEM_RCU handling. IMO this needs a bit more
thought and should be tackled outside of a fix series, so it's not
attempted here.
It's time to start moving in the "non-owning refs have MEM_RCU
lifetime" direction. As mentioned in that comment, using
bpf_mem_free_rcu for all local kptrs - not just refcounted - is
necessarily the first step towards that goal. This patch does so.
After this patch the memory pointed to by all local kptrs will not be
reused until RCU grace period elapses. The verifier's understanding of
non-owning ref validity and the clobbering logic it uses to enforce
that understanding are not changed here, that'll happen gradually in
future work, including further patches in the series.
[0]: https://lore.kernel.org/all/20230821193311.3290257-1-davemarchevsky@fb.com/
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20231107085639.3016113-4-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refcounted local kptrs are kptrs to user-defined types with a
bpf_refcount field. Recent commits ([0], [1]) modified the lifetime of
refcounted local kptrs such that the underlying memory is not reused
until RCU grace period has elapsed.
Separately, verification of bpf_refcount_acquire calls currently
succeeds for MAYBE_NULL non-owning reference input, which is a problem
as bpf_refcount_acquire_impl has no handling for this case.
This patch takes advantage of aforementioned lifetime changes to tag
bpf_refcount_acquire_impl kfunc KF_RCU, thereby preventing MAYBE_NULL
input to the kfunc. The KF_RCU flag applies to all kfunc params; it's
fine for it to apply to the void *meta__ign param as that's populated by
the verifier and is tagged __ign regardless.
[0]: commit 7e26cd12ad ("bpf: Use bpf_mem_free_rcu when
bpf_obj_dropping refcounted nodes") is the actual change to
allocation behaivor
[1]: commit 0816b8c6bf ("bpf: Consider non-owning refs to refcounted
nodes RCU protected") modified verifier understanding of
refcounted local kptrs to match [0]'s changes
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Fixes: 7c50b1cb76 ("bpf: Add bpf_refcount_acquire kfunc")
Link: https://lore.kernel.org/r/20231107085639.3016113-2-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The addition of is_reg_const() in commit 171de12646d2 ("bpf: generalize
is_branch_taken to handle all conditional jumps in one place") has made the
register_is_const() redundant. Give the former has more feature, plus the
fact the latter is only used in one place, replace register_is_const() with
is_reg_const(), and remove the definition of register_is_const.
This requires moving the definition of is_reg_const() further up. And since
the comment of reg_const_value() reference is_reg_const(), move it up as
well.
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231108140043.12282-1-shung-hsi.yu@suse.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Similar to ARG_PTR_TO_CONST_STR for BPF helpers, KF_ARG_PTR_TO_CONST_STR
specifies kfunc args that point to const strings. Annotation "__str" is
used to specify kfunc arg of type KF_ARG_PTR_TO_CONST_STR. Also, add
documentation for the "__str" annotation.
bpf_get_file_xattr() will be the first kfunc that uses this type.
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://lore.kernel.org/bpf/20231107045725.2278852-4-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
ARG_PTR_TO_CONST_STR is used to specify constant string args for BPF
helpers. The logic that verifies a reg is ARG_PTR_TO_CONST_STR is
implemented in check_func_arg().
As we introduce kfuncs with constant string args, it is necessary to
do the same check for kfuncs (in check_kfunc_args). Factor out the logic
for ARG_PTR_TO_CONST_STR to a new check_reg_const_str() so that it can be
reused.
check_func_arg() ensures check_reg_const_str() is only called with reg of
type PTR_TO_MAP_VALUE. Add a redundent type check in check_reg_const_str()
to avoid misuse in the future. Other than this redundent check, there is
no change in behavior.
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://lore.kernel.org/bpf/20231107045725.2278852-3-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Different types of bpf dynptr have different internal data storage.
Specifically, SKB and XDP type of dynptr may have non-continuous data.
Therefore, it is not always safe to directly access dynptr->data.
Add __bpf_dynptr_data and __bpf_dynptr_data_rw to replace direct access to
dynptr->data.
Update bpf_verify_pkcs7_signature to use __bpf_dynptr_data instead of
dynptr->data.
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://lore.kernel.org/bpf/20231107045725.2278852-2-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When looking up an element in LPM trie, the condition 'matchlen ==
trie->max_prefixlen' will never return true, if key->prefixlen is larger
than trie->max_prefixlen. Consequently all elements in the LPM trie will
be visited and no element is returned in the end.
To resolve this, check key->prefixlen first before walking the LPM trie.
Fixes: b95a5c4db0 ("bpf: add a longest prefix match trie map implementation")
Signed-off-by: Florian Lehner <dev@der-flo.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231105085801.3742-1-dev@der-flo.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Change reg_set_min_max() to take FALSE/TRUE sets of two registers each,
instead of assuming that we are always comparing to a constant. For now
we still assume that right-hand side registers are constants (and make
sure that's the case by swapping src/dst regs, if necessary), but
subsequent patches will remove this limitation.
reg_set_min_max() is now called unconditionally for any register
comparison, so that might include pointer vs pointer. This makes it
consistent with is_branch_taken() generality. But we currently only
support adjustments based on SCALAR vs SCALAR comparisons, so
reg_set_min_max() has to guard itself againts pointers.
Taking two by two registers allows to further unify and simplify
check_cond_jmp_op() logic. We utilize fake register for BPF_K
conditional jump case, just like with is_branch_taken() part.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-18-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Similarly to is_branch_taken()-related refactorings, start preparing
reg_set_min_max() to handle more generic case of two non-const
registers. Start with renaming arguments to accommodate later addition
of second register as an input argument.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-17-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Combine 32-bit and 64-bit is_branch_taken logic for SCALAR_VALUE
registers. It makes it easier to see parallels between two domains
(32-bit and 64-bit), and makes subsequent refactoring more
straightforward.
No functional changes.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-16-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Make is_branch_taken() a single entry point for branch pruning decision
making, handling both pointer vs pointer, pointer vs scalar, and scalar
vs scalar cases in one place. This also nicely cleans up check_cond_jmp_op().
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-15-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move is_branch_taken() slightly down. In subsequent patched we'll need
both flip_opcode() and is_pkt_ptr_branch_taken() for is_branch_taken(),
but instead of sprinkling forward declarations around, it makes more
sense to move is_branch_taken() lower below is_pkt_ptr_branch_taken(),
and also keep it closer to very tightly related reg_set_min_max(), as
they are two critical parts of the same SCALAR range tracking logic.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-14-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
While still assuming that second register is a constant, generalize
is_branch_taken-related code to accept two registers instead of register
plus explicit constant value. This also, as a side effect, allows to
simplify check_cond_jmp_op() by unifying BPF_K case with BPF_X case, for
which we use a fake register to represent BPF_K's imm constant as
a register.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231102033759.2541186-13-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Just taking mundane refactoring bits out into a separate patch. No
functional changes.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231102033759.2541186-12-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When performing 32-bit conditional operation operating on lower 32 bits
of a full 64-bit register, register full value isn't changed. We just
potentially gain new knowledge about that register's lower 32 bits.
Unfortunately, __reg_combine_{32,64}_into_{64,32} logic that
reg_set_min_max() performs as a last step, can lose information in some
cases due to __mark_reg64_unbounded() and __reg_assign_32_into_64().
That's bad and completely unnecessary. Especially __reg_assign_32_into_64()
looks completely out of place here, because we are not performing
zero-extending subregister assignment during conditional jump.
So this patch replaced __reg_combine_* with just a normal
reg_bounds_sync() which will do a proper job of deriving u64/s64 bounds
from u32/s32, and vice versa (among all other combinations).
__reg_combine_64_into_32() is also used in one more place,
coerce_reg_to_size(), while handling 1- and 2-byte register loads.
Looking into this, it seems like besides marking subregister as
unbounded before performing reg_bounds_sync(), we were also performing
deduction of smin32/smax32 and umin32/umax32 bounds from respective
smin/smax and umin/umax bounds. It's now redundant as reg_bounds_sync()
performs all the same logic more generically (e.g., without unnecessary
assumption that upper 32 bits of full register should be zero).
Long story short, we remove __reg_combine_64_into_32() completely, and
coerce_reg_to_size() now only does resetting subreg to unbounded and then
performing reg_bounds_sync() to recover as much information as possible
from 64-bit umin/umax and smin/smax bounds, set explicitly in
coerce_reg_to_size() earlier.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231102033759.2541186-10-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
There are cases (caught by subsequent reg_bounds tests in selftests/bpf)
where performing one round of __reg_deduce_bounds() doesn't propagate
all the information from, say, s32 to u32 bounds and than from newly
learned u32 bounds back to u64 and s64. So perform __reg_deduce_bounds()
twice to make sure such derivations are propagated fully after
reg_bounds_sync().
One such example is test `(s64)[0xffffffff00000001; 0] (u64)<
0xffffffff00000000` from selftest patch from this patch set. It demonstrates an
intricate dance of u64 -> s64 -> u64 -> u32 bounds adjustments, which requires
two rounds of __reg_deduce_bounds(). Here are corresponding refinement log from
selftest, showing evolution of knowledge.
REFINING (FALSE R1) (u64)SRC=[0xffffffff00000000; U64_MAX] (u64)DST_OLD=[0; U64_MAX] (u64)DST_NEW=[0xffffffff00000000; U64_MAX]
REFINING (FALSE R1) (u64)SRC=[0xffffffff00000000; U64_MAX] (s64)DST_OLD=[0xffffffff00000001; 0] (s64)DST_NEW=[0xffffffff00000001; -1]
REFINING (FALSE R1) (s64)SRC=[0xffffffff00000001; -1] (u64)DST_OLD=[0xffffffff00000000; U64_MAX] (u64)DST_NEW=[0xffffffff00000001; U64_MAX]
REFINING (FALSE R1) (u64)SRC=[0xffffffff00000001; U64_MAX] (u32)DST_OLD=[0; U32_MAX] (u32)DST_NEW=[1; U32_MAX]
R1 initially has smin/smax set to [0xffffffff00000001; -1], while umin/umax is
unknown. After (u64)< comparison, in FALSE branch we gain knowledge that
umin/umax is [0xffffffff00000000; U64_MAX]. That causes smin/smax to learn that
zero can't happen and upper bound is -1. Then smin/smax is adjusted from
umin/umax improving lower bound from 0xffffffff00000000 to 0xffffffff00000001.
And then eventually umin32/umax32 bounds are drived from umin/umax and become
[1; U32_MAX].
Selftest in the last patch is actually implementing a multi-round fixed-point
convergence logic, but so far all the tests are handled by two rounds of
reg_bounds_sync() on the verifier state, so we keep it simple for now.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a few interesting cases in which we can tighten 64-bit bounds based
on newly learnt information about 32-bit bounds. E.g., when full u64/s64
registers are used in BPF program, and then eventually compared as
u32/s32. The latter comparison doesn't change the value of full
register, but it does impose new restrictions on possible lower 32 bits
of such full registers. And we can use that to derive additional full
register bounds information.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231102033759.2541186-8-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a special case where we can derive valid s32 bounds from umin/umax
or smin/smax by stitching together negative s32 subrange and
non-negative s32 subrange. That requires upper 32 bits to form a [N, N+1]
range in u32 domain (taking into account wrap around, so 0xffffffff
to 0x00000000 is a valid [N, N+1] range in this sense). See code comment
for concrete examples.
Eduard Zingerman also provided an alternative explanation ([0]) for more
mathematically inclined readers:
Suppose:
. there are numbers a, b, c
. 2**31 <= b < 2**32
. 0 <= c < 2**31
. umin = 2**32 * a + b
. umax = 2**32 * (a + 1) + c
The number of values in the range represented by [umin; umax] is:
. N = umax - umin + 1 = 2**32 + c - b + 1
. min(N) = 2**32 + 0 - (2**32-1) + 1 = 2, with b = 2**32-1, c = 0
. max(N) = 2**32 + (2**31 - 1) - 2**31 + 1 = 2**32, with b = 2**31, c = 2**31-1
Hence [(s32)b; (s32)c] forms a valid range.
[0] https://lore.kernel.org/bpf/d7af631802f0cfae20df77fe70068702d24bbd31.camel@gmail.com/
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Comments in code try to explain the idea behind why this is correct.
Please check the code and comments.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
All the logic that applies to u64 vs s64, equally applies for u32 vs s32
relationships (just taken in a smaller 32-bit numeric space). So do the
same deduction of smin32/smax32 from umin32/umax32, if we can.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add smin/smax derivation from appropriate umin/umax values. Previously the
logic was surprisingly asymmetric, trying to derive umin/umax from smin/smax
(if possible), but not trying to do the same in the other direction. A simple
addition to __reg64_deduce_bounds() fixes this.
Added also generic comment about u64/s64 ranges and their relationship.
Hopefully that helps readers to understand all the bounds deductions
a bit better.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task) in verifier.c wanted to
teach BPF verifier that bpf_iter__task -> task is a trusted ptr. But it
doesn't work well.
The reason is, bpf_iter__task -> task would go through btf_ctx_access()
which enforces the reg_type of 'task' is ctx_arg_info->reg_type, and in
task_iter.c, we actually explicitly declare that the
ctx_arg_info->reg_type is PTR_TO_BTF_ID_OR_NULL.
Actually we have a previous case like this[1] where PTR_TRUSTED is added to
the arg flag for map_iter.
This patch sets ctx_arg_info->reg_type is PTR_TO_BTF_ID_OR_NULL |
PTR_TRUSTED in task_reg_info.
Similarly, bpf_cgroup_reg_info -> cgroup is also PTR_TRUSTED since we are
under the protection of cgroup_mutex and we would check cgroup_is_dead()
in __cgroup_iter_seq_show().
This patch is to improve the user experience of the newly introduced
bpf_iter_css_task kfunc before hitting the mainline. The Fixes tag is
pointing to the commit introduced the bpf_iter_css_task kfunc.
Link[1]:https://lore.kernel.org/all/20230706133932.45883-3-aspsk@isovalent.com/
Fixes: 9c66dc94b6 ("bpf: Introduce css_task open-coded iterator kfuncs")
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231107132204.912120-2-zhouchuyi@bytedance.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
BPF_END and BPF_NEG has a different specification for the source bit in
the opcode compared to other ALU/ALU64 instructions, and is either
reserved or use to specify the byte swap endianness. In both cases the
source bit does not encode source operand location, and src_reg is a
reserved field.
backtrack_insn() currently does not differentiate BPF_END and BPF_NEG
from other ALU/ALU64 instructions, which leads to r0 being incorrectly
marked as precise when processing BPF_ALU | BPF_TO_BE | BPF_END
instructions. This commit teaches backtrack_insn() to correctly mark
precision for such case.
While precise tracking of BPF_NEG and other BPF_END instructions are
correct and does not need fixing, this commit opt to process all BPF_NEG
and BPF_END instructions within the same if-clause to better align with
current convention used in the verifier (e.g. check_alu_op).
Fixes: b5dc0163d8 ("bpf: precise scalar_value tracking")
Cc: stable@vger.kernel.org
Reported-by: Mohamed Mahmoud <mmahmoud@redhat.com>
Closes: https://lore.kernel.org/r/87jzrrwptf.fsf@toke.dk
Tested-by: Toke Høiland-Jørgensen <toke@redhat.com>
Tested-by: Tao Lyu <tao.lyu@epfl.ch>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231102053913.12004-2-shung-hsi.yu@suse.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The newly added open-coded css_task iter would try to hold the global
css_set_lock in bpf_iter_css_task_new, so the bpf side has to be careful in
where it allows to use this iter. The mainly concern is dead locking on
css_set_lock. check_css_task_iter_allowlist() in verifier enforced css_task
can only be used in bpf_lsm hooks and sleepable bpf_iter.
This patch relax the allowlist for css_task iter. Any lsm and any iter
(even non-sleepable) and any sleepable are safe since they would not hold
the css_set_lock before entering BPF progs context.
This patch also fixes the misused BPF_TRACE_ITER in
check_css_task_iter_allowlist which compared bpf_prog_type with
bpf_attach_type.
Fixes: 9c66dc94b6 ("bpf: Introduce css_task open-coded iterator kfuncs")
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231031050438.93297-2-zhouchuyi@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When there are concurrent uref release and bpf timer init operations,
the following sequence diagram is possible. It will break the guarantee
provided by bpf_timer: bpf_timer will still be alive after userspace
application releases or unpins the map. It also will lead to kmemleak
for old kernel version which doesn't release bpf_timer when map is
released.
bpf program X:
bpf_timer_init()
lock timer->lock
read timer->timer as NULL
read map->usercnt != 0
process Y:
close(map_fd)
// put last uref
bpf_map_put_uref()
atomic_dec_and_test(map->usercnt)
array_map_free_timers()
bpf_timer_cancel_and_free()
// just return
read timer->timer is NULL
t = bpf_map_kmalloc_node()
timer->timer = t
unlock timer->lock
Fix the problem by checking map->usercnt after timer->timer is assigned,
so when there are concurrent uref release and bpf timer init, either
bpf_timer_cancel_and_free() from uref release reads a no-NULL timer
or the newly-added atomic64_read() returns a zero usercnt.
Because atomic_dec_and_test(map->usercnt) and READ_ONCE(timer->timer)
in bpf_timer_cancel_and_free() are not protected by a lock, so add
a memory barrier to guarantee the order between map->usercnt and
timer->timer. Also use WRITE_ONCE(timer->timer, x) to match the lockless
read of timer->timer in bpf_timer_cancel_and_free().
Reported-by: Hsin-Wei Hung <hsinweih@uci.edu>
Closes: https://lore.kernel.org/bpf/CABcoxUaT2k9hWsS1tNgXyoU3E-=PuOgMn737qK984fbFmfYixQ@mail.gmail.com
Fixes: b00628b1c7 ("bpf: Introduce bpf timers.")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231030063616.1653024-1-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF kfuncs are meant to be called from BPF programs. Accordingly, most
kfuncs are not called from anywhere in the kernel, which the
-Wmissing-prototypes warning is unhappy about. We've peppered
__diag_ignore_all("-Wmissing-prototypes", ... everywhere kfuncs are
defined in the codebase to suppress this warning.
This patch adds two macros meant to bound one or many kfunc definitions.
All existing kfunc definitions which use these __diag calls to suppress
-Wmissing-prototypes are migrated to use the newly-introduced macros.
A new __diag_ignore_all - for "-Wmissing-declarations" - is added to the
__bpf_kfunc_start_defs macro based on feedback from Andrii on an earlier
version of this patch [0] and another recent mailing list thread [1].
In the future we might need to ignore different warnings or do other
kfunc-specific things. This change will make it easier to make such
modifications for all kfunc defs.
[0]: https://lore.kernel.org/bpf/CAEf4BzaE5dRWtK6RPLnjTW-MW9sx9K3Fn6uwqCTChK2Dcb1Xig@mail.gmail.com/
[1]: https://lore.kernel.org/bpf/ZT+2qCc%2FaXep0%2FLf@krava/
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20231031215625.2343848-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Our MPTCP CI complained [1] -- and KBuild too -- that it was no longer
possible to build the kernel without CONFIG_CGROUPS:
kernel/bpf/task_iter.c: In function 'bpf_iter_css_task_new':
kernel/bpf/task_iter.c:919:14: error: 'CSS_TASK_ITER_PROCS' undeclared (first use in this function)
919 | case CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED:
| ^~~~~~~~~~~~~~~~~~~
kernel/bpf/task_iter.c:919:14: note: each undeclared identifier is reported only once for each function it appears in
kernel/bpf/task_iter.c:919:36: error: 'CSS_TASK_ITER_THREADED' undeclared (first use in this function)
919 | case CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED:
| ^~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/task_iter.c:927:60: error: invalid application of 'sizeof' to incomplete type 'struct css_task_iter'
927 | kit->css_it = bpf_mem_alloc(&bpf_global_ma, sizeof(struct css_task_iter));
| ^~~~~~
kernel/bpf/task_iter.c:930:9: error: implicit declaration of function 'css_task_iter_start'; did you mean 'task_seq_start'? [-Werror=implicit-function-declaration]
930 | css_task_iter_start(css, flags, kit->css_it);
| ^~~~~~~~~~~~~~~~~~~
| task_seq_start
kernel/bpf/task_iter.c: In function 'bpf_iter_css_task_next':
kernel/bpf/task_iter.c:940:16: error: implicit declaration of function 'css_task_iter_next'; did you mean 'class_dev_iter_next'? [-Werror=implicit-function-declaration]
940 | return css_task_iter_next(kit->css_it);
| ^~~~~~~~~~~~~~~~~~
| class_dev_iter_next
kernel/bpf/task_iter.c:940:16: error: returning 'int' from a function with return type 'struct task_struct *' makes pointer from integer without a cast [-Werror=int-conversion]
940 | return css_task_iter_next(kit->css_it);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/task_iter.c: In function 'bpf_iter_css_task_destroy':
kernel/bpf/task_iter.c:949:9: error: implicit declaration of function 'css_task_iter_end' [-Werror=implicit-function-declaration]
949 | css_task_iter_end(kit->css_it);
| ^~~~~~~~~~~~~~~~~
This patch simply surrounds with a #ifdef the new code requiring CGroups
support. It seems enough for the compiler and this is similar to
bpf_iter_css_{new,next,destroy}() functions where no other #ifdef have
been added in kernel/bpf/helpers.c and in the selftests.
Fixes: 9c66dc94b6 ("bpf: Introduce css_task open-coded iterator kfuncs")
Link: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/6665206927
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310260528.aHWgVFqq-lkp@intel.com/
Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
[ added missing ifdefs for BTF_ID cgroup definitions ]
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20231101181601.1493271-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'for-6.7/io_uring-sockopt-2023-10-30' of git://git.kernel.dk/linux
Pull io_uring {get,set}sockopt support from Jens Axboe:
"This adds support for using getsockopt and setsockopt via io_uring.
The main use cases for this is to enable use of direct descriptors,
rather than first instantiating a normal file descriptor, doing the
option tweaking needed, then turning it into a direct descriptor. With
this support, we can avoid needing a regular file descriptor
completely.
The net and bpf bits have been signed off on their side"
* tag 'for-6.7/io_uring-sockopt-2023-10-30' of git://git.kernel.dk/linux:
selftests/bpf/sockopt: Add io_uring support
io_uring/cmd: Introduce SOCKET_URING_OP_SETSOCKOPT
io_uring/cmd: Introduce SOCKET_URING_OP_GETSOCKOPT
io_uring/cmd: return -EOPNOTSUPP if net is disabled
selftests/net: Extract uring helpers to be reusable
tools headers: Grab copy of io_uring.h
io_uring/cmd: Pass compat mode in issue_flags
net/socket: Break down __sys_getsockopt
net/socket: Break down __sys_setsockopt
bpf: Add sockptr support for setsockopt
bpf: Add sockptr support for getsockopt
Core & protocols
----------------
- Support usec resolution of TCP timestamps, enabled selectively by
a route attribute.
- Defer regular TCP ACK while processing socket backlog, try to send
a cumulative ACK at the end. Increase single TCP flow performance
on a 200Gbit NIC by 20% (100Gbit -> 120Gbit).
- The Fair Queuing (FQ) packet scheduler:
- add built-in 3 band prio / WRR scheduling
- support bypass if the qdisc is mostly idle (5% speed up for TCP RR)
- improve inactive flow reporting
- optimize the layout of structures for better cache locality
- Support TCP Authentication Option (RFC 5925, TCP-AO), a more modern
replacement for the old MD5 option.
- Add more retransmission timeout (RTO) related statistics to TCP_INFO.
- Support sending fragmented skbs over vsock sockets.
- Make sure we send SIGPIPE for vsock sockets if socket was shutdown().
- Add sysctl for ignoring lower limit on lifetime in Router
Advertisement PIO, based on an in-progress IETF draft.
- Add sysctl to control activation of TCP ping-pong mode.
- Add sysctl to make connection timeout in MPTCP configurable.
- Support rcvlowat and notsent_lowat on MPTCP sockets, to help apps
limit the number of wakeups.
- Support netlink GET for MDB (multicast forwarding), allowing user
space to request a single MDB entry instead of dumping the entire
table.
- Support selective FDB flushing in the VXLAN tunnel driver.
- Allow limiting learned FDB entries in bridges, prevent OOM attacks.
- Allow controlling via configfs netconsole targets which were created
via the kernel cmdline at boot, rather than via configfs at runtime.
- Support multiple PTP timestamp event queue readers with different
filters.
- MCTP over I3C.
BPF
---
- Add new veth-like netdevice where BPF program defines the logic
of the xmit routine. It can operate in L3 and L2 mode.
- Support exceptions - allow asserting conditions which should
never be true but are hard for the verifier to infer.
With some extra flexibility around handling of the exit / failure.
https://lwn.net/Articles/938435/
- Add support for local per-cpu kptr, allow allocating and storing
per-cpu objects in maps. Access to those objects operates on
the value for the current CPU. This allows to deprecate local
one-off implementations of per-CPU storage like
BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE maps.
- Extend cgroup BPF sockaddr hooks for UNIX sockets. The use case is
for systemd to re-implement the LogNamespace feature which allows
running multiple instances of systemd-journald to process the logs
of different services.
- Enable open-coded task_vma iteration, after maple tree conversion
made it hard to directly walk VMAs in tracing programs.
- Add open-coded task, css_task and css iterator support.
One of the use cases is customizable OOM victim selection via BPF.
- Allow source address selection with bpf_*_fib_lookup().
- Add ability to pin BPF timer to the current CPU.
- Prevent creation of infinite loops by combining tail calls and
fentry/fexit programs.
- Add missed stats for kprobes to retrieve the number of missed kprobe
executions and subsequent executions of BPF programs.
- Inherit system settings for CPU security mitigations.
- Add BPF v4 CPU instruction support for arm32 and s390x.
Changes to common code
----------------------
- overflow: add DEFINE_FLEX() for on-stack definition of structs
with flexible array members.
- Process doc update with more guidance for reviewers.
Driver API
----------
- Simplify locking in WiFi (cfg80211 and mac80211 layers), use wiphy
mutex in most places and remove a lot of smaller locks.
- Create a common DPLL configuration API. Allow configuring
and querying state of PLL circuits used for clock syntonization,
in network time distribution.
- Unify fragmented and full page allocation APIs in page pool code.
Let drivers be ignorant of PAGE_SIZE.
- Rework PHY state machine to avoid races with calls to phy_stop().
- Notify DSA drivers of MAC address changes on user ports, improve
correctness of offloads which depend on matching port MAC addresses.
- Allow antenna control on injected WiFi frames.
- Reduce the number of variants of napi_schedule().
- Simplify error handling when composing devlink health messages.
Misc
----
- A lot of KCSAN data race "fixes", from Eric.
- A lot of __counted_by() annotations, from Kees.
- A lot of strncpy -> strscpy and printf format fixes.
- Replace master/slave terminology with conduit/user in DSA drivers.
- Handful of KUnit tests for netdev and WiFi core.
Removed
-------
- AppleTalk COPS.
- AppleTalk ipddp.
- TI AR7 CPMAC Ethernet driver.
Drivers
-------
- Ethernet high-speed NICs:
- Intel (100G, ice, idpf):
- add a driver for the Intel E2000 IPUs
- make CRC/FCS stripping configurable
- cross-timestamping for E823 devices
- basic support for E830 devices
- use aux-bus for managing client drivers
- i40e: report firmware versions via devlink
- nVidia/Mellanox:
- support 4-port NICs
- increase max number of channels to 256
- optimize / parallelize SF creation flow
- Broadcom (bnxt):
- enhance NIC temperature reporting
- support PAM4 speeds and lane configuration
- Marvell OcteonTX2:
- PTP pulse-per-second output support
- enable hardware timestamping for VFs
- Solarflare/AMD:
- conntrack NAT offload and offload for tunnels
- Wangxun (ngbe/txgbe):
- expose HW statistics
- Pensando/AMD:
- support PCI level reset
- narrow down the condition under which skbs are linearized
- Netronome/Corigine (nfp):
- support CHACHA20-POLY1305 crypto in IPsec offload
- Ethernet NICs embedded, slower, virtual:
- Synopsys (stmmac):
- add Loongson-1 SoC support
- enable use of HW queues with no offload capabilities
- enable PPS input support on all 5 channels
- increase TX coalesce timer to 5ms
- RealTek USB (r8152): improve efficiency of Rx by using GRO frags
- xen: support SW packet timestamping
- add drivers for implementations based on TI's PRUSS (AM64x EVM)
- nVidia/Mellanox Ethernet datacenter switches:
- avoid poor HW resource use on Spectrum-4 by better block selection
for IPv6 multicast forwarding and ordering of blocks in ACL region
- Ethernet embedded switches:
- Microchip:
- support configuring the drive strength for EMI compliance
- ksz9477: partial ACL support
- ksz9477: HSR offload
- ksz9477: Wake on LAN
- Realtek:
- rtl8366rb: respect device tree config of the CPU port
- Ethernet PHYs:
- support Broadcom BCM5221 PHYs
- TI dp83867: support hardware LED blinking
- CAN:
- add support for Linux-PHY based CAN transceivers
- at91_can: clean up and use rx-offload helpers
- WiFi:
- MediaTek (mt76):
- new sub-driver for mt7925 USB/PCIe devices
- HW wireless <> Ethernet bridging in MT7988 chips
- mt7603/mt7628 stability improvements
- Qualcomm (ath12k):
- WCN7850:
- enable 320 MHz channels in 6 GHz band
- hardware rfkill support
- enable IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS
to make scan faster
- read board data variant name from SMBIOS
- QCN9274: mesh support
- RealTek (rtw89):
- TDMA-based multi-channel concurrency (MCC)
- Silicon Labs (wfx):
- Remain-On-Channel (ROC) support
- Bluetooth:
- ISO: many improvements for broadcast support
- mark BCM4378/BCM4387 as BROKEN_LE_CODED
- add support for QCA2066
- btmtksdio: enable Bluetooth wakeup from suspend
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-next-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
"Core & protocols:
- Support usec resolution of TCP timestamps, enabled selectively by a
route attribute.
- Defer regular TCP ACK while processing socket backlog, try to send
a cumulative ACK at the end. Increase single TCP flow performance
on a 200Gbit NIC by 20% (100Gbit -> 120Gbit).
- The Fair Queuing (FQ) packet scheduler:
- add built-in 3 band prio / WRR scheduling
- support bypass if the qdisc is mostly idle (5% speed up for TCP RR)
- improve inactive flow reporting
- optimize the layout of structures for better cache locality
- Support TCP Authentication Option (RFC 5925, TCP-AO), a more modern
replacement for the old MD5 option.
- Add more retransmission timeout (RTO) related statistics to
TCP_INFO.
- Support sending fragmented skbs over vsock sockets.
- Make sure we send SIGPIPE for vsock sockets if socket was
shutdown().
- Add sysctl for ignoring lower limit on lifetime in Router
Advertisement PIO, based on an in-progress IETF draft.
- Add sysctl to control activation of TCP ping-pong mode.
- Add sysctl to make connection timeout in MPTCP configurable.
- Support rcvlowat and notsent_lowat on MPTCP sockets, to help apps
limit the number of wakeups.
- Support netlink GET for MDB (multicast forwarding), allowing user
space to request a single MDB entry instead of dumping the entire
table.
- Support selective FDB flushing in the VXLAN tunnel driver.
- Allow limiting learned FDB entries in bridges, prevent OOM attacks.
- Allow controlling via configfs netconsole targets which were
created via the kernel cmdline at boot, rather than via configfs at
runtime.
- Support multiple PTP timestamp event queue readers with different
filters.
- MCTP over I3C.
BPF:
- Add new veth-like netdevice where BPF program defines the logic of
the xmit routine. It can operate in L3 and L2 mode.
- Support exceptions - allow asserting conditions which should never
be true but are hard for the verifier to infer. With some extra
flexibility around handling of the exit / failure:
https://lwn.net/Articles/938435/
- Add support for local per-cpu kptr, allow allocating and storing
per-cpu objects in maps. Access to those objects operates on the
value for the current CPU.
This allows to deprecate local one-off implementations of per-CPU
storage like BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE maps.
- Extend cgroup BPF sockaddr hooks for UNIX sockets. The use case is
for systemd to re-implement the LogNamespace feature which allows
running multiple instances of systemd-journald to process the logs
of different services.
- Enable open-coded task_vma iteration, after maple tree conversion
made it hard to directly walk VMAs in tracing programs.
- Add open-coded task, css_task and css iterator support. One of the
use cases is customizable OOM victim selection via BPF.
- Allow source address selection with bpf_*_fib_lookup().
- Add ability to pin BPF timer to the current CPU.
- Prevent creation of infinite loops by combining tail calls and
fentry/fexit programs.
- Add missed stats for kprobes to retrieve the number of missed
kprobe executions and subsequent executions of BPF programs.
- Inherit system settings for CPU security mitigations.
- Add BPF v4 CPU instruction support for arm32 and s390x.
Changes to common code:
- overflow: add DEFINE_FLEX() for on-stack definition of structs with
flexible array members.
- Process doc update with more guidance for reviewers.
Driver API:
- Simplify locking in WiFi (cfg80211 and mac80211 layers), use wiphy
mutex in most places and remove a lot of smaller locks.
- Create a common DPLL configuration API. Allow configuring and
querying state of PLL circuits used for clock syntonization, in
network time distribution.
- Unify fragmented and full page allocation APIs in page pool code.
Let drivers be ignorant of PAGE_SIZE.
- Rework PHY state machine to avoid races with calls to phy_stop().
- Notify DSA drivers of MAC address changes on user ports, improve
correctness of offloads which depend on matching port MAC
addresses.
- Allow antenna control on injected WiFi frames.
- Reduce the number of variants of napi_schedule().
- Simplify error handling when composing devlink health messages.
Misc:
- A lot of KCSAN data race "fixes", from Eric.
- A lot of __counted_by() annotations, from Kees.
- A lot of strncpy -> strscpy and printf format fixes.
- Replace master/slave terminology with conduit/user in DSA drivers.
- Handful of KUnit tests for netdev and WiFi core.
Removed:
- AppleTalk COPS.
- AppleTalk ipddp.
- TI AR7 CPMAC Ethernet driver.
Drivers:
- Ethernet high-speed NICs:
- Intel (100G, ice, idpf):
- add a driver for the Intel E2000 IPUs
- make CRC/FCS stripping configurable
- cross-timestamping for E823 devices
- basic support for E830 devices
- use aux-bus for managing client drivers
- i40e: report firmware versions via devlink
- nVidia/Mellanox:
- support 4-port NICs
- increase max number of channels to 256
- optimize / parallelize SF creation flow
- Broadcom (bnxt):
- enhance NIC temperature reporting
- support PAM4 speeds and lane configuration
- Marvell OcteonTX2:
- PTP pulse-per-second output support
- enable hardware timestamping for VFs
- Solarflare/AMD:
- conntrack NAT offload and offload for tunnels
- Wangxun (ngbe/txgbe):
- expose HW statistics
- Pensando/AMD:
- support PCI level reset
- narrow down the condition under which skbs are linearized
- Netronome/Corigine (nfp):
- support CHACHA20-POLY1305 crypto in IPsec offload
- Ethernet NICs embedded, slower, virtual:
- Synopsys (stmmac):
- add Loongson-1 SoC support
- enable use of HW queues with no offload capabilities
- enable PPS input support on all 5 channels
- increase TX coalesce timer to 5ms
- RealTek USB (r8152): improve efficiency of Rx by using GRO frags
- xen: support SW packet timestamping
- add drivers for implementations based on TI's PRUSS (AM64x EVM)
- nVidia/Mellanox Ethernet datacenter switches:
- avoid poor HW resource use on Spectrum-4 by better block
selection for IPv6 multicast forwarding and ordering of blocks
in ACL region
- Ethernet embedded switches:
- Microchip:
- support configuring the drive strength for EMI compliance
- ksz9477: partial ACL support
- ksz9477: HSR offload
- ksz9477: Wake on LAN
- Realtek:
- rtl8366rb: respect device tree config of the CPU port
- Ethernet PHYs:
- support Broadcom BCM5221 PHYs
- TI dp83867: support hardware LED blinking
- CAN:
- add support for Linux-PHY based CAN transceivers
- at91_can: clean up and use rx-offload helpers
- WiFi:
- MediaTek (mt76):
- new sub-driver for mt7925 USB/PCIe devices
- HW wireless <> Ethernet bridging in MT7988 chips
- mt7603/mt7628 stability improvements
- Qualcomm (ath12k):
- WCN7850:
- enable 320 MHz channels in 6 GHz band
- hardware rfkill support
- enable IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS to
make scan faster
- read board data variant name from SMBIOS
- QCN9274: mesh support
- RealTek (rtw89):
- TDMA-based multi-channel concurrency (MCC)
- Silicon Labs (wfx):
- Remain-On-Channel (ROC) support
- Bluetooth:
- ISO: many improvements for broadcast support
- mark BCM4378/BCM4387 as BROKEN_LE_CODED
- add support for QCA2066
- btmtksdio: enable Bluetooth wakeup from suspend"
* tag 'net-next-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1816 commits)
net: pcs: xpcs: Add 2500BASE-X case in get state for XPCS drivers
net: bpf: Use sockopt_lock_sock() in ip_sock_set_tos()
net: mana: Use xdp_set_features_flag instead of direct assignment
vxlan: Cleanup IFLA_VXLAN_PORT_RANGE entry in vxlan_get_size()
iavf: delete the iavf client interface
iavf: add a common function for undoing the interrupt scheme
iavf: use unregister_netdev
iavf: rely on netdev's own registered state
iavf: fix the waiting time for initial reset
iavf: in iavf_down, don't queue watchdog_task if comms failed
iavf: simplify mutex_trylock+sleep loops
iavf: fix comments about old bit locks
doc/netlink: Update schema to support cmd-cnt-name and cmd-max-name
tools: ynl: introduce option to process unknown attributes or types
ipvlan: properly track tx_errors
netdevsim: Block until all devices are released
nfp: using napi_build_skb() to replace build_skb()
net: dsa: microchip: ksz9477: Fix spelling mistake "Enery" -> "Energy"
net: dsa: microchip: Ensure Stable PME Pin State for Wake-on-LAN
net: dsa: microchip: Refactor switch shutdown routine for WoL preparation
...
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Merge tag 'vfs-6.7.ctime' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull vfs inode time accessor updates from Christian Brauner:
"This finishes the conversion of all inode time fields to accessor
functions as discussed on list. Changing timestamps manually as we
used to do before is error prone. Using accessors function makes this
robust.
It does not contain the switch of the time fields to discrete 64 bit
integers to replace struct timespec and free up space in struct inode.
But after this, the switch can be trivially made and the patch should
only affect the vfs if we decide to do it"
* tag 'vfs-6.7.ctime' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (86 commits)
fs: rename inode i_atime and i_mtime fields
security: convert to new timestamp accessors
selinux: convert to new timestamp accessors
apparmor: convert to new timestamp accessors
sunrpc: convert to new timestamp accessors
mm: convert to new timestamp accessors
bpf: convert to new timestamp accessors
ipc: convert to new timestamp accessors
linux: convert to new timestamp accessors
zonefs: convert to new timestamp accessors
xfs: convert to new timestamp accessors
vboxsf: convert to new timestamp accessors
ufs: convert to new timestamp accessors
udf: convert to new timestamp accessors
ubifs: convert to new timestamp accessors
tracefs: convert to new timestamp accessors
sysv: convert to new timestamp accessors
squashfs: convert to new timestamp accessors
server: convert to new timestamp accessors
client: convert to new timestamp accessors
...
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Merge tag 'vfs-6.7.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"This contains the usual miscellaneous features, cleanups, and fixes
for vfs and individual fses.
Features:
- Rename and export helpers that get write access to a mount. They
are used in overlayfs to get write access to the upper mount.
- Print the pretty name of the root device on boot failure. This
helps in scenarios where we would usually only print
"unknown-block(1,2)".
- Add an internal SB_I_NOUMASK flag. This is another part in the
endless POSIX ACL saga in a way.
When POSIX ACLs are enabled via SB_POSIXACL the vfs cannot strip
the umask because if the relevant inode has POSIX ACLs set it might
take the umask from there. But if the inode doesn't have any POSIX
ACLs set then we apply the umask in the filesytem itself. So we end
up with:
(1) no SB_POSIXACL -> strip umask in vfs
(2) SB_POSIXACL -> strip umask in filesystem
The umask semantics associated with SB_POSIXACL allowed filesystems
that don't even support POSIX ACLs at all to raise SB_POSIXACL
purely to avoid umask stripping. That specifically means NFS v4 and
Overlayfs. NFS v4 does it because it delegates this to the server
and Overlayfs because it needs to delegate umask stripping to the
upper filesystem, i.e., the filesystem used as the writable layer.
This went so far that SB_POSIXACL is raised eve on kernels that
don't even have POSIX ACL support at all.
Stop this blatant abuse and add SB_I_NOUMASK which is an internal
superblock flag that filesystems can raise to opt out of umask
handling. That should really only be the two mentioned above. It's
not that we want any filesystems to do this. Ideally we have all
umask handling always in the vfs.
- Make overlayfs use SB_I_NOUMASK too.
- Now that we have SB_I_NOUMASK, stop checking for SB_POSIXACL in
IS_POSIXACL() if the kernel doesn't have support for it. This is a
very old patch but it's only possible to do this now with the wider
cleanup that was done.
- Follow-up work on fake path handling from last cycle. Citing mostly
from Amir:
When overlayfs was first merged, overlayfs files of regular files
and directories, the ones that are installed in file table, had a
"fake" path, namely, f_path is the overlayfs path and f_inode is
the "real" inode on the underlying filesystem.
In v6.5, we took another small step by introducing of the
backing_file container and the file_real_path() helper. This change
allowed vfs and filesystem code to get the "real" path of an
overlayfs backing file. With this change, we were able to make
fsnotify work correctly and report events on the "real" filesystem
objects that were accessed via overlayfs.
This method works fine, but it still leaves the vfs vulnerable to
new code that is not aware of files with fake path. A recent
example is commit db1d1e8b98 ("IMA: use vfs_getattr_nosec to get
the i_version"). This commit uses direct referencing to f_path in
IMA code that otherwise uses file_inode() and file_dentry() to
reference the filesystem objects that it is measuring.
This contains work to switch things around: instead of having
filesystem code opt-in to get the "real" path, have generic code
opt-in for the "fake" path in the few places that it is needed.
Is it far more likely that new filesystems code that does not use
the file_dentry() and file_real_path() helpers will end up causing
crashes or averting LSM/audit rules if we keep the "fake" path
exposed by default.
This change already makes file_dentry() moot, but for now we did
not change this helper just added a WARN_ON() in ovl_d_real() to
catch if we have made any wrong assumptions.
After the dust settles on this change, we can make file_dentry() a
plain accessor and we can drop the inode argument to ->d_real().
- Switch struct file to SLAB_TYPESAFE_BY_RCU. This looks like a small
change but it really isn't and I would like to see everyone on
their tippie toes for any possible bugs from this work.
Essentially we've been doing most of what SLAB_TYPESAFE_BY_RCU for
files since a very long time because of the nasty interactions
between the SCM_RIGHTS file descriptor garbage collection. So
extending it makes a lot of sense but it is a subtle change. There
are almost no places that fiddle with file rcu semantics directly
and the ones that did mess around with struct file internal under
rcu have been made to stop doing that because it really was always
dodgy.
I forgot to put in the link tag for this change and the discussion
in the commit so adding it into the merge message:
https://lore.kernel.org/r/20230926162228.68666-1-mjguzik@gmail.com
Cleanups:
- Various smaller pipe cleanups including the removal of a spin lock
that was only used to protect against writes without pipe_lock()
from O_NOTIFICATION_PIPE aka watch queues. As that was never
implemented remove the additional locking from pipe_write().
- Annotate struct watch_filter with the new __counted_by attribute.
- Clarify do_unlinkat() cleanup so that it doesn't look like an extra
iput() is done that would cause issues.
- Simplify file cleanup when the file has never been opened.
- Use module helper instead of open-coding it.
- Predict error unlikely for stale retry.
- Use WRITE_ONCE() for mount expiry field instead of just commenting
that one hopes the compiler doesn't get smart.
Fixes:
- Fix readahead on block devices.
- Fix writeback when layztime is enabled and inodes whose timestamp
is the only thing that changed reside on wb->b_dirty_time. This
caused excessively large zombie memory cgroup when lazytime was
enabled as such inodes weren't handled fast enough.
- Convert BUG_ON() to WARN_ON_ONCE() in open_last_lookups()"
* tag 'vfs-6.7.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (26 commits)
file, i915: fix file reference for mmap_singleton()
vfs: Convert BUG_ON to WARN_ON_ONCE in open_last_lookups
writeback, cgroup: switch inodes with dirty timestamps to release dying cgwbs
chardev: Simplify usage of try_module_get()
ovl: rely on SB_I_NOUMASK
fs: fix umask on NFS with CONFIG_FS_POSIX_ACL=n
fs: store real path instead of fake path in backing file f_path
fs: create helper file_user_path() for user displayed mapped file path
fs: get mnt_writers count for an open backing file's real path
vfs: stop counting on gcc not messing with mnt_expiry_mark if not asked
vfs: predict the error in retry_estale as unlikely
backing file: free directly
vfs: fix readahead(2) on block devices
io_uring: use files_lookup_fd_locked()
file: convert to SLAB_TYPESAFE_BY_RCU
vfs: shave work on failed file open
fs: simplify misleading code to remove ambiguity regarding ihold()/iput()
watch_queue: Annotate struct watch_filter with __counted_by
fs/pipe: use spinlock in pipe_read() only if there is a watch_queue
fs/pipe: remove unnecessary spinlock from pipe_write()
...
There are two possible mismatched alloc and free cases in BPF memory
allocator:
1) allocate from cache X but free by cache Y with a different unit_size
2) allocate from per-cpu cache but free by kmalloc cache or vice versa
So add more WARN_ON_ONCE checks in free_bulk() and __free_by_rcu() to
spot these mismatched alloc and free early.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231021014959.3563841-1-houtao@huaweicloud.com
This work adds a new, minimal BPF-programmable device called "netkit"
(former PoC code-name "meta") we recently presented at LSF/MM/BPF. The
core idea is that BPF programs are executed within the drivers xmit routine
and therefore e.g. in case of containers/Pods moving BPF processing closer
to the source.
One of the goals was that in case of Pod egress traffic, this allows to
move BPF programs from hostns tcx ingress into the device itself, providing
earlier drop or forward mechanisms, for example, if the BPF program
determines that the skb must be sent out of the node, then a redirect to
the physical device can take place directly without going through per-CPU
backlog queue. This helps to shift processing for such traffic from softirq
to process context, leading to better scheduling decisions/performance (see
measurements in the slides).
In this initial version, the netkit device ships as a pair, but we plan to
extend this further so it can also operate in single device mode. The pair
comes with a primary and a peer device. Only the primary device, typically
residing in hostns, can manage BPF programs for itself and its peer. The
peer device is designated for containers/Pods and cannot attach/detach
BPF programs. Upon the device creation, the user can set the default policy
to 'pass' or 'drop' for the case when no BPF program is attached.
Additionally, the device can be operated in L3 (default) or L2 mode. The
management of BPF programs is done via bpf_mprog, so that multi-attach is
supported right from the beginning with similar API and dependency controls
as tcx. For details on the latter see commit 053c8e1f23 ("bpf: Add generic
attach/detach/query API for multi-progs"). tc BPF compatibility is provided,
so that existing programs can be easily migrated.
Going forward, we plan to use netkit devices in Cilium as the main device
type for connecting Pods. They will be operated in L3 mode in order to
simplify a Pod's neighbor management and the peer will operate in default
drop mode, so that no traffic is leaving between the time when a Pod is
brought up by the CNI plugin and programs attached by the agent.
Additionally, the programs we attach via tcx on the physical devices are
using bpf_redirect_peer() for inbound traffic into netkit device, hence the
latter is also supporting the ndo_get_peer_dev callback. Similarly, we use
bpf_redirect_neigh() for the way out, pushing from netkit peer to phys device
directly. Also, BIG TCP is supported on netkit device. For the follow-up
work in single device mode, we plan to convert Cilium's cilium_host/_net
devices into a single one.
An extensive test suite for checking device operations and the BPF program
and link management API comes as BPF selftests in this series.
Co-developed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://github.com/borkmann/iproute2/tree/pr/netkit
Link: http://vger.kernel.org/bpfconf2023_material/tcx_meta_netdev_borkmann.pdf (24ff.)
Link: https://lore.kernel.org/r/20231024214904.29825-2-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
When determining if an if/else branch will always or never be taken, use
signed range knowledge in addition to currently used unsigned range knowledge.
If either signed or unsigned range suggests that condition is always/never
taken, return corresponding branch_taken verdict.
Current use of unsigned range for this seems arbitrary and unnecessarily
incomplete. It is possible for *signed* operations to be performed on
register, which could "invalidate" unsigned range for that register. In such
case branch_taken will be artificially useless, even if we can still tell
that some constant is outside of register value range based on its signed
bounds.
veristat-based validation shows zero differences across selftests, Cilium,
and Meta-internal BPF object files.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/bpf/20231022205743.72352-2-andrii@kernel.org
The bpf_user_ringbuf_drain() BPF_CALL function uses an atomic_set()
immediately preceded by smp_mb__before_atomic() so as to order storing
of ring-buffer consumer and producer positions prior to the atomic_set()
call's clearing of the ->busy flag, as follows:
smp_mb__before_atomic();
atomic_set(&rb->busy, 0);
Although this works given current architectures and implementations, and
given that this only needs to order prior writes against a later write.
However, it does so by accident because the smp_mb__before_atomic()
is only guaranteed to work with read-modify-write atomic operations, and
not at all with things like atomic_set() and atomic_read().
Note especially that smp_mb__before_atomic() will not, repeat *not*,
order the prior write to "a" before the subsequent non-read-modify-write
atomic read from "b", even on strongly ordered systems such as x86:
WRITE_ONCE(a, 1);
smp_mb__before_atomic();
r1 = atomic_read(&b);
Therefore, replace the smp_mb__before_atomic() and atomic_set() with
atomic_set_release() as follows:
atomic_set_release(&rb->busy, 0);
This is no slower (and sometimes is faster) than the original, and also
provides a formal guarantee of ordering that the original lacks.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/ec86d38e-cfb4-44aa-8fdb-6c925922d93c@paulmck-laptop
htab_lock_bucket uses the following logic to avoid recursion:
1. preempt_disable();
2. check percpu counter htab->map_locked[hash] for recursion;
2.1. if map_lock[hash] is already taken, return -BUSY;
3. raw_spin_lock_irqsave();
However, if an IRQ hits between 2 and 3, BPF programs attached to the IRQ
logic will not able to access the same hash of the hashtab and get -EBUSY.
This -EBUSY is not really necessary. Fix it by disabling IRQ before
checking map_locked:
1. preempt_disable();
2. local_irq_save();
3. check percpu counter htab->map_locked[hash] for recursion;
3.1. if map_lock[hash] is already taken, return -BUSY;
4. raw_spin_lock().
Similarly, use raw_spin_unlock() and local_irq_restore() in
htab_unlock_bucket().
Fixes: 20b6cc34ea ("bpf: Avoid hashtab deadlock with map_locked")
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/7a9576222aa40b1c84ad3a9ba3e64011d1a04d41.camel@linux.ibm.com
Link: https://lore.kernel.org/bpf/20231012055741.3375999-1-song@kernel.org
Additional logging in is_state_visited(): if infinite loop is detected
print full verifier state for both current and equivalent states.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231024000917.12153-8-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
It turns out that .branches > 0 in is_state_visited() is not a
sufficient condition to identify if two verifier states form a loop
when iterators convergence is computed. This commit adds logic to
distinguish situations like below:
(I) initial (II) initial
| |
V V
.---------> hdr ..
| | |
| V V
| .------... .------..
| | | | |
| V V V V
| ... ... .-> hdr ..
| | | | | |
| V V | V V
| succ <- cur | succ <- cur
| | | |
| V | V
| ... | ...
| | | |
'----' '----'
For both (I) and (II) successor 'succ' of the current state 'cur' was
previously explored and has branches count at 0. However, loop entry
'hdr' corresponding to 'succ' might be a part of current DFS path.
If that is the case 'succ' and 'cur' are members of the same loop
and have to be compared exactly.
Co-developed-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Co-developed-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Reviewed-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231024000917.12153-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Convergence for open coded iterators is computed in is_state_visited()
by examining states with branches count > 1 and using states_equal().
states_equal() computes sub-state relation using read and precision marks.
Read and precision marks are propagated from children states,
thus are not guaranteed to be complete inside a loop when branches
count > 1. This could be demonstrated using the following unsafe program:
1. r7 = -16
2. r6 = bpf_get_prandom_u32()
3. while (bpf_iter_num_next(&fp[-8])) {
4. if (r6 != 42) {
5. r7 = -32
6. r6 = bpf_get_prandom_u32()
7. continue
8. }
9. r0 = r10
10. r0 += r7
11. r8 = *(u64 *)(r0 + 0)
12. r6 = bpf_get_prandom_u32()
13. }
Here verifier would first visit path 1-3, create a checkpoint at 3
with r7=-16, continue to 4-7,3 with r7=-32.
Because instructions at 9-12 had not been visitied yet existing
checkpoint at 3 does not have read or precision mark for r7.
Thus states_equal() would return true and verifier would discard
current state, thus unsafe memory access at 11 would not be caught.
This commit fixes this loophole by introducing exact state comparisons
for iterator convergence logic:
- registers are compared using regs_exact() regardless of read or
precision marks;
- stack slots have to have identical type.
Unfortunately, this is too strict even for simple programs like below:
i = 0;
while(iter_next(&it))
i++;
At each iteration step i++ would produce a new distinct state and
eventually instruction processing limit would be reached.
To avoid such behavior speculatively forget (widen) range for
imprecise scalar registers, if those registers were not precise at the
end of the previous iteration and do not match exactly.
This a conservative heuristic that allows to verify wide range of
programs, however it precludes verification of programs that conjure
an imprecise value on the first loop iteration and use it as precise
on the second.
Test case iter_task_vma_for_each() presents one of such cases:
unsigned int seen = 0;
...
bpf_for_each(task_vma, vma, task, 0) {
if (seen >= 1000)
break;
...
seen++;
}
Here clang generates the following code:
<LBB0_4>:
24: r8 = r6 ; stash current value of
... body ... 'seen'
29: r1 = r10
30: r1 += -0x8
31: call bpf_iter_task_vma_next
32: r6 += 0x1 ; seen++;
33: if r0 == 0x0 goto +0x2 <LBB0_6> ; exit on next() == NULL
34: r7 += 0x10
35: if r8 < 0x3e7 goto -0xc <LBB0_4> ; loop on seen < 1000
<LBB0_6>:
... exit ...
Note that counter in r6 is copied to r8 and then incremented,
conditional jump is done using r8. Because of this precision mark for
r6 lags one state behind of precision mark on r8 and widening logic
kicks in.
Adding barrier_var(seen) after conditional is sufficient to force
clang use the same register for both counting and conditional jump.
This issue was discussed in the thread [1] which was started by
Andrew Werner <awerner32@gmail.com> demonstrating a similar bug
in callback functions handling. The callbacks would be addressed
in a followup patch.
[1] https://lore.kernel.org/bpf/97a90da09404c65c8e810cf83c94ac703705dc0e.camel@gmail.com/
Co-developed-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Co-developed-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231024000917.12153-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Extract same_callsites() from clean_live_states() as a utility function.
This function would be used by the next patch in the set.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231024000917.12153-3-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Subsequent patches would make use of explored_state() function.
Move it up to avoid adding unnecessary prototype.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231024000917.12153-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The following warning was reported when running "./test_progs -t
test_bpf_ma/percpu_free_through_map_free":
------------[ cut here ]------------
WARNING: CPU: 1 PID: 68 at kernel/bpf/memalloc.c:342
CPU: 1 PID: 68 Comm: kworker/u16:2 Not tainted 6.6.0-rc2+ #222
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Workqueue: events_unbound bpf_map_free_deferred
RIP: 0010:bpf_mem_refill+0x21c/0x2a0
......
Call Trace:
<IRQ>
? bpf_mem_refill+0x21c/0x2a0
irq_work_single+0x27/0x70
irq_work_run_list+0x2a/0x40
irq_work_run+0x18/0x40
__sysvec_irq_work+0x1c/0xc0
sysvec_irq_work+0x73/0x90
</IRQ>
<TASK>
asm_sysvec_irq_work+0x1b/0x20
RIP: 0010:unit_free+0x50/0x80
......
bpf_mem_free+0x46/0x60
__bpf_obj_drop_impl+0x40/0x90
bpf_obj_free_fields+0x17d/0x1a0
array_map_free+0x6b/0x170
bpf_map_free_deferred+0x54/0xa0
process_scheduled_works+0xba/0x370
worker_thread+0x16d/0x2e0
kthread+0x105/0x140
ret_from_fork+0x39/0x60
ret_from_fork_asm+0x1b/0x30
</TASK>
---[ end trace 0000000000000000 ]---
The reason is simple: __bpf_obj_drop_impl() does not know the freeing
field is a per-cpu pointer and it uses bpf_global_ma to free the
pointer. Because bpf_global_ma is not a per-cpu allocator, so ksize() is
used to select the corresponding cache. The bpf_mem_cache with 16-bytes
unit_size will always be selected to do the unmatched free and it will
trigger the warning in free_bulk() eventually.
Because per-cpu kptr doesn't support list or rb-tree now, so fix the
problem by only checking whether or not the type of kptr is per-cpu in
bpf_obj_free_fields(), and using bpf_global_percpu_ma to these kptrs.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231020133202.4043247-7-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
For bpf_global_percpu_ma, the pointer passed to bpf_mem_free_rcu() is
allocated by kmalloc() and its size is fixed (16-bytes on x86-64). So
no matter which cache allocates the dynamic per-cpu area, on x86-64
cache[2] will always be used to free the per-cpu area.
Fix the unbalance by checking whether the bpf memory allocator is
per-cpu or not and use pcpu_alloc_size() instead of ksize() to
find the correct cache for per-cpu free.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231020133202.4043247-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
With pcpu_alloc_size() in place, check whether or not the size of
the dynamic per-cpu area is matched with unit_size.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231020133202.4043247-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When using task_iter to iterate all threads of a specific task, we enforce
that the user must pass a valid task pointer to ensure safety. However,
when iterating all threads/process in the system, BPF verifier still
require a valid ptr instead of "nullable" pointer, even though it's
pointless, which is a kind of surprising from usability standpoint. It
would be nice if we could let that kfunc accept a explicit null pointer
when we are using BPF_TASK_ITER_ALL_{PROCS, THREADS} and a valid pointer
when using BPF_TASK_ITER_THREAD.
Given a trival kfunc:
__bpf_kfunc void FN(struct TYPE_A *obj);
BPF Prog would reject a nullptr for obj. The error info is:
"arg#x pointer type xx xx must point to scalar, or struct with scalar"
reported by get_kfunc_ptr_arg_type(). The reg->type is SCALAR_VALUE and
the btf type of ref_t is not scalar or scalar_struct which leads to the
rejection of get_kfunc_ptr_arg_type.
This patch add "__nullable" annotation:
__bpf_kfunc void FN(struct TYPE_A *obj__nullable);
Here __nullable indicates obj can be optional, user can pass a explicit
nullptr or a normal TYPE_A pointer. In get_kfunc_ptr_arg_type(), we will
detect whether the current arg is optional and register is null, If so,
return a new kfunc_ptr_arg_type KF_ARG_PTR_TO_NULL and skip to the next
arg in check_kfunc_args().
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231018061746.111364-7-zhouchuyi@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
css_iter and task_iter should be used in rcu section. Specifically, in
sleepable progs explicit bpf_rcu_read_lock() is needed before use these
iters. In normal bpf progs that have implicit rcu_read_lock(), it's OK to
use them directly.
This patch adds a new a KF flag KF_RCU_PROTECTED for bpf_iter_task_new and
bpf_iter_css_new. It means the kfunc should be used in RCU CS. We check
whether we are in rcu cs before we want to invoke this kfunc. If the rcu
protection is guaranteed, we would let st->type = PTR_TO_STACK | MEM_RCU.
Once user do rcu_unlock during the iteration, state MEM_RCU of regs would
be cleared. is_iter_reg_valid_init() will reject if reg->type is UNTRUSTED.
It is worth noting that currently, bpf_rcu_read_unlock does not
clear the state of the STACK_ITER reg, since bpf_for_each_spilled_reg
only considers STACK_SPILL. This patch also let bpf_for_each_spilled_reg
search STACK_ITER.
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231018061746.111364-6-zhouchuyi@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This Patch adds kfuncs bpf_iter_css_{new,next,destroy} which allow
creation and manipulation of struct bpf_iter_css in open-coded iterator
style. These kfuncs actually wrapps css_next_descendant_{pre, post}.
css_iter can be used to:
1) iterating a sepcific cgroup tree with pre/post/up order
2) iterating cgroup_subsystem in BPF Prog, like
for_each_mem_cgroup_tree/cpuset_for_each_descendant_pre in kernel.
The API design is consistent with cgroup_iter. bpf_iter_css_new accepts
parameters defining iteration order and starting css. Here we also reuse
BPF_CGROUP_ITER_DESCENDANTS_PRE, BPF_CGROUP_ITER_DESCENDANTS_POST,
BPF_CGROUP_ITER_ANCESTORS_UP enums.
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20231018061746.111364-5-zhouchuyi@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch adds kfuncs bpf_iter_task_{new,next,destroy} which allow
creation and manipulation of struct bpf_iter_task in open-coded iterator
style. BPF programs can use these kfuncs or through bpf_for_each macro to
iterate all processes in the system.
The API design keep consistent with SEC("iter/task"). bpf_iter_task_new()
accepts a specific task and iterating type which allows:
1. iterating all process in the system (BPF_TASK_ITER_ALL_PROCS)
2. iterating all threads in the system (BPF_TASK_ITER_ALL_THREADS)
3. iterating all threads of a specific task (BPF_TASK_ITER_PROC_THREADS)
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Link: https://lore.kernel.org/r/20231018061746.111364-4-zhouchuyi@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch adds kfuncs bpf_iter_css_task_{new,next,destroy} which allow
creation and manipulation of struct bpf_iter_css_task in open-coded
iterator style. These kfuncs actually wrapps css_task_iter_{start,next,
end}. BPF programs can use these kfuncs through bpf_for_each macro for
iteration of all tasks under a css.
css_task_iter_*() would try to get the global spin-lock *css_set_lock*, so
the bpf side has to be careful in where it allows to use this iter.
Currently we only allow it in bpf_lsm and bpf iter-s.
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20231018061746.111364-3-zhouchuyi@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The whole network stack uses sockptr, and while it doesn't move to
something more modern, let's use sockptr in setsockptr BPF hooks, so, it
could be used by other callers.
The main motivation for this change is to use it in the io_uring
{g,s}etsockopt(), which will use a userspace pointer for *optval, but, a
kernel value for optlen.
Link: https://lore.kernel.org/all/ZSArfLaaGcfd8LH8@gmail.com/
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20231016134750.1381153-3-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The whole network stack uses sockptr, and while it doesn't move to
something more modern, let's use sockptr in getsockptr BPF hooks, so, it
could be used by other callers.
The main motivation for this change is to use it in the io_uring
{g,s}etsockopt(), which will use a userspace pointer for *optval, but, a
kernel value for optlen.
Link: https://lore.kernel.org/all/ZSArfLaaGcfd8LH8@gmail.com/
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20231016134750.1381153-2-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In recent discussions around some performance improvements in the file
handling area we discussed switching the file cache to rely on
SLAB_TYPESAFE_BY_RCU which allows us to get rid of call_rcu() based
freeing for files completely. This is a pretty sensitive change overall
but it might actually be worth doing.
The main downside is the subtlety. The other one is that we should
really wait for Jann's patch to land that enables KASAN to handle
SLAB_TYPESAFE_BY_RCU UAFs. Currently it doesn't but a patch for this
exists.
With SLAB_TYPESAFE_BY_RCU objects may be freed and reused multiple times
which requires a few changes. So it isn't sufficient anymore to just
acquire a reference to the file in question under rcu using
atomic_long_inc_not_zero() since the file might have already been
recycled and someone else might have bumped the reference.
In other words, callers might see reference count bumps from newer
users. For this reason it is necessary to verify that the pointer is the
same before and after the reference count increment. This pattern can be
seen in get_file_rcu() and __files_get_rcu().
In addition, it isn't possible to access or check fields in struct file
without first aqcuiring a reference on it. Not doing that was always
very dodgy and it was only usable for non-pointer data in struct file.
With SLAB_TYPESAFE_BY_RCU it is necessary that callers first acquire a
reference under rcu or they must hold the files_lock of the fdtable.
Failing to do either one of this is a bug.
Thanks to Jann for pointing out that we need to ensure memory ordering
between reallocations and pointer check by ensuring that all subsequent
loads have a dependency on the second load in get_file_rcu() and
providing a fixup that was folded into this patch.
Cc: Jann Horn <jannh@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
When employed within a sleepable program not under RCU protection, the
use of 'bpf_task_under_cgroup()' may trigger a warning in the kernel log,
particularly when CONFIG_PROVE_RCU is enabled:
[ 1259.662357] WARNING: suspicious RCU usage
[ 1259.662358] 6.5.0+ #33 Not tainted
[ 1259.662360] -----------------------------
[ 1259.662361] include/linux/cgroup.h:423 suspicious rcu_dereference_check() usage!
Other info that might help to debug this:
[ 1259.662366] rcu_scheduler_active = 2, debug_locks = 1
[ 1259.662368] 1 lock held by trace/72954:
[ 1259.662369] #0: ffffffffb5e3eda0 (rcu_read_lock_trace){....}-{0:0}, at: __bpf_prog_enter_sleepable+0x0/0xb0
Stack backtrace:
[ 1259.662385] CPU: 50 PID: 72954 Comm: trace Kdump: loaded Not tainted 6.5.0+ #33
[ 1259.662391] Call Trace:
[ 1259.662393] <TASK>
[ 1259.662395] dump_stack_lvl+0x6e/0x90
[ 1259.662401] dump_stack+0x10/0x20
[ 1259.662404] lockdep_rcu_suspicious+0x163/0x1b0
[ 1259.662412] task_css_set.part.0+0x23/0x30
[ 1259.662417] bpf_task_under_cgroup+0xe7/0xf0
[ 1259.662422] bpf_prog_7fffba481a3bcf88_lsm_run+0x5c/0x93
[ 1259.662431] bpf_trampoline_6442505574+0x60/0x1000
[ 1259.662439] bpf_lsm_bpf+0x5/0x20
[ 1259.662443] ? security_bpf+0x32/0x50
[ 1259.662452] __sys_bpf+0xe6/0xdd0
[ 1259.662463] __x64_sys_bpf+0x1a/0x30
[ 1259.662467] do_syscall_64+0x38/0x90
[ 1259.662472] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 1259.662479] RIP: 0033:0x7f487baf8e29
[...]
[ 1259.662504] </TASK>
This issue can be reproduced by executing a straightforward program, as
demonstrated below:
SEC("lsm.s/bpf")
int BPF_PROG(lsm_run, int cmd, union bpf_attr *attr, unsigned int size)
{
struct cgroup *cgrp = NULL;
struct task_struct *task;
int ret = 0;
if (cmd != BPF_LINK_CREATE)
return 0;
// The cgroup2 should be mounted first
cgrp = bpf_cgroup_from_id(1);
if (!cgrp)
goto out;
task = bpf_get_current_task_btf();
if (bpf_task_under_cgroup(task, cgrp))
ret = -1;
bpf_cgroup_release(cgrp);
out:
return ret;
}
After running the program, if you subsequently execute another BPF program,
you will encounter the warning.
It's worth noting that task_under_cgroup_hierarchy() is also utilized by
bpf_current_task_under_cgroup(). However, bpf_current_task_under_cgroup()
doesn't exhibit this issue because it cannot be used in sleepable BPF
programs.
Fixes: b5ad4cdc46 ("bpf: Add bpf_task_under_cgroup() kfunc")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Cc: Feng Zhou <zhoufeng.zf@bytedance.com>
Cc: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20231007135945.4306-1-laoar.shao@gmail.com
A few drivers were missing a xdp_do_flush() invocation after
XDP_REDIRECT.
Add three helper functions each for one of the per-CPU lists. Return
true if the per-CPU list is non-empty and flush the list.
Add xdp_do_check_flushed() which invokes each helper functions and
creates a warning if one of the functions had a non-empty list.
Hide everything behind CONFIG_DEBUG_NET.
Suggested-by: Jesper Dangaard Brouer <hawk@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20231016125738.Yt79p1uF@linutronix.de
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2023-10-16
We've added 90 non-merge commits during the last 25 day(s) which contain
a total of 120 files changed, 3519 insertions(+), 895 deletions(-).
The main changes are:
1) Add missed stats for kprobes to retrieve the number of missed kprobe
executions and subsequent executions of BPF programs, from Jiri Olsa.
2) Add cgroup BPF sockaddr hooks for unix sockets. The use case is
for systemd to reimplement the LogNamespace feature which allows
running multiple instances of systemd-journald to process the logs
of different services, from Daan De Meyer.
3) Implement BPF CPUv4 support for s390x BPF JIT, from Ilya Leoshkevich.
4) Improve BPF verifier log output for scalar registers to better
disambiguate their internal state wrt defaults vs min/max values
matching, from Andrii Nakryiko.
5) Extend the BPF fib lookup helpers for IPv4/IPv6 to support retrieving
the source IP address with a new BPF_FIB_LOOKUP_SRC flag,
from Martynas Pumputis.
6) Add support for open-coded task_vma iterator to help with symbolization
for BPF-collected user stacks, from Dave Marchevsky.
7) Add libbpf getters for accessing individual BPF ring buffers which
is useful for polling them individually, for example, from Martin Kelly.
8) Extend AF_XDP selftests to validate the SHARED_UMEM feature,
from Tushar Vyavahare.
9) Improve BPF selftests cross-building support for riscv arch,
from Björn Töpel.
10) Add the ability to pin a BPF timer to the same calling CPU,
from David Vernet.
11) Fix libbpf's bpf_tracing.h macros for riscv to use the generic
implementation of PT_REGS_SYSCALL_REGS() to access syscall arguments,
from Alexandre Ghiti.
12) Extend libbpf to support symbol versioning for uprobes, from Hengqi Chen.
13) Fix bpftool's skeleton code generation to guarantee that ELF data
is 8 byte aligned, from Ian Rogers.
14) Inherit system-wide cpu_mitigations_off() setting for Spectre v1/v4
security mitigations in BPF verifier, from Yafang Shao.
15) Annotate struct bpf_stack_map with __counted_by attribute to prepare
BPF side for upcoming __counted_by compiler support, from Kees Cook.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (90 commits)
bpf: Ensure proper register state printing for cond jumps
bpf: Disambiguate SCALAR register state output in verifier logs
selftests/bpf: Make align selftests more robust
selftests/bpf: Improve missed_kprobe_recursion test robustness
selftests/bpf: Improve percpu_alloc test robustness
selftests/bpf: Add tests for open-coded task_vma iter
bpf: Introduce task_vma open-coded iterator kfuncs
selftests/bpf: Rename bpf_iter_task_vma.c to bpf_iter_task_vmas.c
bpf: Don't explicitly emit BTF for struct btf_iter_num
bpf: Change syscall_nr type to int in struct syscall_tp_t
net/bpf: Avoid unused "sin_addr_len" warning when CONFIG_CGROUP_BPF is not set
bpf: Avoid unnecessary audit log for CPU security mitigations
selftests/bpf: Add tests for cgroup unix socket address hooks
selftests/bpf: Make sure mount directory exists
documentation/bpf: Document cgroup unix socket address hooks
bpftool: Add support for cgroup unix socket address hooks
libbpf: Add support for cgroup unix socket address hooks
bpf: Implement cgroup sockaddr hooks for unix sockets
bpf: Add bpf_sock_addr_set_sun_path() to allow writing unix sockaddr from bpf
bpf: Propagate modified uaddrlen from cgroup sockaddr programs
...
====================
Link: https://lore.kernel.org/r/20231016204803.30153-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Verifier emits relevant register state involved in any given instruction
next to it after `;` to the right, if possible. Or, worst case, on the
separate line repeating instruction index.
E.g., a nice and simple case would be:
2: (d5) if r0 s<= 0x0 goto pc+1 ; R0_w=0
But if there is some intervening extra output (e.g., precision
backtracking log) involved, we are supposed to see the state after the
precision backtrack log:
4: (75) if r0 s>= 0x0 goto pc+1
mark_precise: frame0: last_idx 4 first_idx 0 subseq_idx -1
mark_precise: frame0: regs=r0 stack= before 2: (d5) if r0 s<= 0x0 goto pc+1
mark_precise: frame0: regs=r0 stack= before 1: (b7) r0 = 0
6: R0_w=0
First off, note that in `6: R0_w=0` instruction index corresponds to the
next instruction, not to the conditional jump instruction itself, which
is wrong and we'll get to that.
But besides that, the above is a happy case that does work today. Yet,
if it so happens that precision backtracking had to traverse some of the
parent states, this `6: R0_w=0` state output would be missing.
This is due to a quirk of print_verifier_state() routine, which performs
mark_verifier_state_clean(env) at the end. This marks all registers as
"non-scratched", which means that subsequent logic to print *relevant*
registers (that is, "scratched ones") fails and doesn't see anything
relevant to print and skips the output altogether.
print_verifier_state() is used both to print instruction context, but
also to print an **entire** verifier state indiscriminately, e.g.,
during precision backtracking (and in a few other situations, like
during entering or exiting subprogram). Which means if we have to print
entire parent state before getting to printing instruction context
state, instruction context is marked as clean and is omitted.
Long story short, this is definitely not intentional. So we fix this
behavior in this patch by teaching print_verifier_state() to clear
scratch state only if it was used to print instruction state, not the
parent/callback state. This is determined by print_all option, so if
it's not set, we don't clear scratch state. This fixes missing
instruction state for these cases.
As for the mismatched instruction index, we fix that by making sure we
call print_insn_state() early inside check_cond_jmp_op() before we
adjusted insn_idx based on jump branch taken logic. And with that we get
desired correct information:
9: (16) if w4 == 0x1 goto pc+9
mark_precise: frame0: last_idx 9 first_idx 9 subseq_idx -1
mark_precise: frame0: parent state regs=r4 stack=: R2_w=1944 R4_rw=P1 R10=fp0
mark_precise: frame0: last_idx 8 first_idx 0 subseq_idx 9
mark_precise: frame0: regs=r4 stack= before 8: (66) if w4 s> 0x3 goto pc+5
mark_precise: frame0: regs=r4 stack= before 7: (b7) r4 = 1
9: R4=1
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20231011223728.3188086-6-andrii@kernel.org
Currently the way that verifier prints SCALAR_VALUE register state (and
PTR_TO_PACKET, which can have var_off and ranges info as well) is very
ambiguous.
In the name of brevity we are trying to eliminate "unnecessary" output
of umin/umax, smin/smax, u32_min/u32_max, and s32_min/s32_max values, if
possible. Current rules are that if any of those have their default
value (which for mins is the minimal value of its respective types: 0,
S32_MIN, or S64_MIN, while for maxs it's U32_MAX, S32_MAX, S64_MAX, or
U64_MAX) *OR* if there is another min/max value that as matching value.
E.g., if smin=100 and umin=100, we'll emit only umin=10, omitting smin
altogether. This approach has a few problems, being both ambiguous and
sort-of incorrect in some cases.
Ambiguity is due to missing value could be either default value or value
of umin/umax or smin/smax. This is especially confusing when we mix
signed and unsigned ranges. Quite often, umin=0 and smin=0, and so we'll
have only `umin=0` leaving anyone reading verifier log to guess whether
smin is actually 0 or it's actually -9223372036854775808 (S64_MIN). And
often times it's important to know, especially when debugging tricky
issues.
"Sort-of incorrectness" comes from mixing negative and positive values.
E.g., if umin is some large positive number, it can be equal to smin
which is, interpreted as signed value, is actually some negative value.
Currently, that smin will be omitted and only umin will be emitted with
a large positive value, giving an impression that smin is also positive.
Anyway, ambiguity is the biggest issue making it impossible to have an
exact understanding of register state, preventing any sort of automated
testing of verifier state based on verifier log. This patch is
attempting to rectify the situation by removing ambiguity, while
minimizing the verboseness of register state output.
The rules are straightforward:
- if some of the values are missing, then it definitely has a default
value. I.e., `umin=0` means that umin is zero, but smin is actually
S64_MIN;
- all the various boundaries that happen to have the same value are
emitted in one equality separated sequence. E.g., if umin and smin are
both 100, we'll emit `smin=umin=100`, making this explicit;
- we do not mix negative and positive values together, and even if
they happen to have the same bit-level value, they will be emitted
separately with proper sign. I.e., if both umax and smax happen to be
0xffffffffffffffff, we'll emit them both separately as
`smax=-1,umax=18446744073709551615`;
- in the name of a bit more uniformity and consistency,
{u32,s32}_{min,max} are renamed to {s,u}{min,max}32, which seems to
improve readability.
The above means that in case of all 4 ranges being, say, [50, 100] range,
we'd previously see hugely ambiguous:
R1=scalar(umin=50,umax=100)
Now, we'll be more explicit:
R1=scalar(smin=umin=smin32=umin32=50,smax=umax=smax32=umax32=100)
This is slightly more verbose, but distinct from the case when we don't
know anything about signed boundaries and 32-bit boundaries, which under
new rules will match the old case:
R1=scalar(umin=50,umax=100)
Also, in the name of simplicity of implementation and consistency, order
for {s,u}32_{min,max} are emitted *before* var_off. Previously they were
emitted afterwards, for unclear reasons.
This patch also includes a few fixes to selftests that expect exact
register state to accommodate slight changes to verifier format. You can
see that the changes are pretty minimal in common cases.
Note, the special case when SCALAR_VALUE register is a known constant
isn't changed, we'll emit constant value once, interpreted as signed
value.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20231011223728.3188086-5-andrii@kernel.org
This patch adds kfuncs bpf_iter_task_vma_{new,next,destroy} which allow
creation and manipulation of struct bpf_iter_task_vma in open-coded
iterator style. BPF programs can use these kfuncs directly or through
bpf_for_each macro for natural-looking iteration of all task vmas.
The implementation borrows heavily from bpf_find_vma helper's locking -
differing only in that it holds the mmap_read lock for all iterations
while the helper only executes its provided callback on a maximum of 1
vma. Aside from locking, struct vma_iterator and vma_next do all the
heavy lifting.
A pointer to an inner data struct, struct bpf_iter_task_vma_data, is the
only field in struct bpf_iter_task_vma. This is because the inner data
struct contains a struct vma_iterator (not ptr), whose size is likely to
change under us. If bpf_iter_task_vma_kern contained vma_iterator directly
such a change would require change in opaque bpf_iter_task_vma struct's
size. So better to allocate vma_iterator using BPF allocator, and since
that alloc must already succeed, might as well allocate all iter fields,
thereby freezing struct bpf_iter_task_vma size.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231013204426.1074286-4-davemarchevsky@fb.com
Commit 6018e1f407 ("bpf: implement numbers iterator") added the
BTF_TYPE_EMIT line that this patch is modifying. The struct btf_iter_num
doesn't exist, so only a forward declaration is emitted in BTF:
FWD 'btf_iter_num' fwd_kind=struct
That commit was probably hoping to ensure that struct bpf_iter_num is
emitted in vmlinux BTF. A previous version of this patch changed the
line to emit the correct type, but Yonghong confirmed that it would
definitely be emitted regardless in [0], so this patch simply removes
the line.
This isn't marked "Fixes" because the extraneous btf_iter_num FWD wasn't
causing any issues that I noticed, aside from mild confusion when I
looked through the code.
[0]: https://lore.kernel.org/bpf/25d08207-43e6-36a8-5e0f-47a913d4cda5@linux.dev/
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231013204426.1074286-2-davemarchevsky@fb.com
Cross-merge networking fixes after downstream PR.
No conflicts.
Adjacent changes:
kernel/bpf/verifier.c
829955981c ("bpf: Fix verifier log for async callback return values")
a923819fb2 ("bpf: Treat first argument as return value for bpf_throw")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
These hooks allows intercepting connect(), getsockname(),
getpeername(), sendmsg() and recvmsg() for unix sockets. The unix
socket hooks get write access to the address length because the
address length is not fixed when dealing with unix sockets and
needs to be modified when a unix socket address is modified by
the hook. Because abstract socket unix addresses start with a
NUL byte, we cannot recalculate the socket address in kernelspace
after running the hook by calculating the length of the unix socket
path using strlen().
These hooks can be used when users want to multiplex syscall to a
single unix socket to multiple different processes behind the scenes
by redirecting the connect() and other syscalls to process specific
sockets.
We do not implement support for intercepting bind() because when
using bind() with unix sockets with a pathname address, this creates
an inode in the filesystem which must be cleaned up. If we rewrite
the address, the user might try to clean up the wrong file, leaking
the socket in the filesystem where it is never cleaned up. Until we
figure out a solution for this (and a use case for intercepting bind()),
we opt to not allow rewriting the sockaddr in bind() calls.
We also implement recvmsg() support for connected streams so that
after a connect() that is modified by a sockaddr hook, any corresponding
recmvsg() on the connected socket can also be modified to make the
connected program think it is connected to the "intended" remote.
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Link: https://lore.kernel.org/r/20231011185113.140426-5-daan.j.demeyer@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
As prep for adding unix socket support to the cgroup sockaddr hooks,
let's add a kfunc bpf_sock_addr_set_sun_path() that allows modifying a unix
sockaddr from bpf. While this is already possible for AF_INET and AF_INET6,
we'll need this kfunc when we add unix socket support since modifying the
address for those requires modifying both the address and the sockaddr
length.
Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Link: https://lore.kernel.org/r/20231011185113.140426-4-daan.j.demeyer@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
As prep for adding unix socket support to the cgroup sockaddr hooks,
let's propagate the sockaddr length back to the caller after running
a bpf cgroup sockaddr hook program. While not important for AF_INET or
AF_INET6, the sockaddr length is important when working with AF_UNIX
sockaddrs as the size of the sockaddr cannot be determined just from the
address family or the sockaddr's contents.
__cgroup_bpf_run_filter_sock_addr() is modified to take the uaddrlen as
an input/output argument. After running the program, the modified sockaddr
length is stored in the uaddrlen pointer.
Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Link: https://lore.kernel.org/r/20231011185113.140426-3-daan.j.demeyer@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
The verifier, as part of check_return_code(), verifies that async
callbacks such as from e.g. timers, will return 0. It does this by
correctly checking that R0->var_off is in tnum_const(0), which
effectively checks that it's in a range of 0. If this condition fails,
however, it prints an error message which says that the value should
have been in (0x0; 0x1). This results in possibly confusing output such
as the following in which an async callback returns 1:
At async callback the register R0 has value (0x1; 0x0) should have been in (0x0; 0x1)
The fix is easy -- we should just pass the tnum_const(0) as the correct
range to verbose_invalid_scalar(), which will then print the following:
At async callback the register R0 has value (0x1; 0x0) should have been in (0x0; 0x0)
Fixes: bfc6bb74e4 ("bpf: Implement verifier support for validation of async callbacks.")
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231009161414.235829-1-void@manifault.com
BPF supports creating high resolution timers using bpf_timer_* helper
functions. Currently, only the BPF_F_TIMER_ABS flag is supported, which
specifies that the timeout should be interpreted as absolute time. It
would also be useful to be able to pin that timer to a core. For
example, if you wanted to make a subset of cores run without timer
interrupts, and only have the timer be invoked on a single core.
This patch adds support for this with a new BPF_F_TIMER_CPU_PIN flag.
When specified, the HRTIMER_MODE_PINNED flag is passed to
hrtimer_start(). A subsequent patch will update selftests to validate.
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20231004162339.200702-2-void@manifault.com
The recently added tcx attachment extended the BPF UAPI for attaching and
detaching by a couple of fields. Those fields are currently only supported
for tcx, other types like cgroups and flow dissector silently ignore the
new fields except for the new flags.
This is problematic once we extend bpf_mprog to older attachment types, since
it's hard to figure out whether the syscall really was successful if the
kernel silently ignores non-zero values.
Explicitly reject non-zero fields relevant to bpf_mprog for attachment types
which don't use the latter yet.
Fixes: e420bed025 ("bpf: Add fd-based tcx multi-prog infra with link support")
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20231006220655.1653-3-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Improve consistency for bpf_mprog_query() API and let the latter also handle
a NULL entry as can be the case for tcx. Instead of returning -ENOENT, we
copy a count of 0 and revision of 1 to user space, so that this can be fed
into a subsequent bpf_mprog_attach() call as expected_revision. A BPF self-
test as part of this series has been added to assert this case.
Suggested-by: Lorenz Bauer <lmb@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20231006220655.1653-2-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
While working on the ebpf-go [0] library integration for bpf_mprog and tcx,
Lorenz noticed that two subsequent BPF_PROG_QUERY requests currently fail. A
typical workflow is to first gather the bpf_mprog count without passing program/
link arrays, followed by the second request which contains the actual array
pointers.
The initial call populates count and revision fields. The second call gets
rejected due to a BPF_PROG_QUERY_LAST_FIELD bug which should point to
query.revision instead of query.link_attach_flags since the former is really
the last member.
It was not noticed in libbpf as bpf_prog_query_opts() always calls bpf(2) with
an on-stack bpf_attr that is memset() each time (and therefore query.revision
was reset to zero).
[0] https://ebpf-go.dev
Fixes: e420bed025 ("bpf: Add fd-based tcx multi-prog infra with link support")
Reported-by: Lorenz Bauer <lmb@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20231006220655.1653-1-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for
array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).
As found with Coccinelle [1], add __counted_by for struct bpf_stack_map.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
Link: https://lore.kernel.org/bpf/20231006201657.work.531-kees@kernel.org
Commit d52b59315b ("bpf: Adjust size_index according to the value of
KMALLOC_MIN_SIZE") uses KMALLOC_MIN_SIZE to adjust size_index, but as
reported by Nathan, the adjustment is not enough, because
__kmalloc_minalign() also decides the minimal alignment of slab object
as shown in new_kmalloc_cache() and its value may be greater than
KMALLOC_MIN_SIZE (e.g., 64 bytes vs 8 bytes under a riscv QEMU VM).
Instead of invoking __kmalloc_minalign() in bpf subsystem to find the
maximal alignment, just using kmalloc_size_roundup() directly to get the
corresponding slab object size for each allocation size. If these two
sizes are unmatched, adjust size_index to select a bpf_mem_cache with
unit_size equal to the object_size of the underlying slab cache for the
allocation size.
Fixes: 822fb26bdb ("bpf: Add a hint to allocated objects.")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/bpf/20230914181407.GA1000274@dev-arch.thelio-3990X/
Signed-off-by: Hou Tao <houtao1@huawei.com>
Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Link: https://lore.kernel.org/r/20230928101558.2594068-1-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add missed value to kprobe attached through perf link info to
hold the stats of missed kprobe handler execution.
The kprobe's missed counter gets incremented when kprobe handler
is not executed due to another kprobe running on the same cpu.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230920213145.1941596-4-jolsa@kernel.org
On the architectures that use bpf_jit_needs_zext(), e.g., s390x, the
verifier incorrectly inserts a zero-extension after BPF_MEMSX, leading
to miscompilations like the one below:
24: 89 1a ff fe 00 00 00 00 "r1 = *(s16 *)(r10 - 2);" # zext_dst set
0x3ff7fdb910e: lgh %r2,-2(%r13,%r0) # load halfword
0x3ff7fdb9114: llgfr %r2,%r2 # wrong!
25: 65 10 00 03 00 00 7f ff if r1 s> 32767 goto +3 <l0_1> # check_cond_jmp_op()
Disable such zero-extensions. The JITs need to insert sign-extension
themselves, if necessary.
Suggested-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Puranjay Mohan <puranjay12@gmail.com>
Link: https://lore.kernel.org/r/20230919101336.2223655-2-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In mark_chain_precision() logic, when we reach the entry to a global
func, it is expected that R1-R5 might be still requested to be marked
precise. This would correspond to some integer input arguments being
tracked as precise. This is all expected and handled as a special case.
What's not expected is that we'll leave backtrack_state structure with
some register bits set. This is because for subsequent precision
propagations backtrack_state is reused without clearing masks, as all
code paths are carefully written in a way to leave empty backtrack_state
with zeroed out masks, for speed.
The fix is trivial, we always clear register bit in the register mask, and
then, optionally, set reg->precise if register is SCALAR_VALUE type.
Reported-by: Chris Mason <clm@meta.com>
Fixes: be2ef81615 ("bpf: allow precision tracking for programs with subprogs")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230918210110.2241458-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
On 32-bit architectures, the pointer width is 32-bit, while we try to
cast from a u64 down to it, the compiler complains on mismatch in
integer size. Fix this by first casting to long which should match
the pointer width on targets supported by Linux.
Fixes: ec5290a178 ("bpf: Prevent KASAN false positive with bpf_throw")
Reported-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Link: https://lore.kernel.org/r/20230918155233.297024-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Alexei Starovoitov says:
====================
The following pull-request contains BPF updates for your *net-next* tree.
We've added 73 non-merge commits during the last 9 day(s) which contain
a total of 79 files changed, 5275 insertions(+), 600 deletions(-).
The main changes are:
1) Basic BTF validation in libbpf, from Andrii Nakryiko.
2) bpf_assert(), bpf_throw(), exceptions in bpf progs, from Kumar Kartikeya Dwivedi.
3) next_thread cleanups, from Oleg Nesterov.
4) Add mcpu=v4 support to arm32, from Puranjay Mohan.
5) Add support for __percpu pointers in bpf progs, from Yonghong Song.
6) Fix bpf tailcall interaction with bpf trampoline, from Leon Hwang.
7) Raise irq_work in bpf_mem_alloc while irqs are disabled to improve refill probabablity, from Hou Tao.
Please consider pulling these changes from:
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
Thanks a lot!
Also thanks to reporters, reviewers and testers of commits in this pull-request:
Alan Maguire, Andrey Konovalov, Dave Marchevsky, "Eric W. Biederman",
Jiri Olsa, Maciej Fijalkowski, Quentin Monnet, Russell King (Oracle),
Song Liu, Stanislav Fomichev, Yonghong Song
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
The kfunc code to handle KF_ARG_PTR_TO_CALLBACK does not check the reg
type before using reg->subprogno. This can accidently permit invalid
pointers from being passed into callback helpers (e.g. silently from
different paths). Likewise, reg->subprogno from the per-register type
union may not be meaningful either. We need to reject any other type
except PTR_TO_FUNC.
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Fixes: 5d92ddc3de ("bpf: Add callback validation to kfunc verifier logic")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-14-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
During testing, it was discovered that extensions to exception callbacks
had no checks, upon running a testcase, the kernel ended up running off
the end of a program having final call as bpf_throw, and hitting int3
instructions.
The reason is that while the default exception callback would have reset
the stack frame to return back to the main program's caller, the
replacing extension program will simply return back to bpf_throw, which
will instead return back to the program and the program will continue
execution, now in an undefined state where anything could happen.
The way to support extensions to an exception callback would be to mark
the BPF_PROG_TYPE_EXT main subprog as an exception_cb, and prevent it
from calling bpf_throw. This would make the JIT produce a prologue that
restores saved registers and reset the stack frame. But let's not do
that until there is a concrete use case for this, and simply disallow
this for now.
Similar issues will exist for fentry and fexit cases, where trampoline
saves data on the stack when invoking exception callback, which however
will then end up resetting the stack frame, and on return, the fexit
program will never will invoked as the return address points to the main
program's caller in the kernel. Instead of additional complexity and
back and forth between the two stacks to enable such a use case, simply
forbid it.
One key point here to note is that currently X86_TAIL_CALL_OFFSET didn't
require any modifications, even though we emit instructions before the
corresponding endbr64 instruction. This is because we ensure that a main
subprog never serves as an exception callback, and therefore the
exception callback (which will be a global subprog) can never serve as
the tail call target, eliminating any discrepancies. However, once we
support a BPF_PROG_TYPE_EXT to also act as an exception callback, it
will end up requiring change to the tail call offset to account for the
extra instructions. For simplicitly, tail calls could be disabled for
such targets.
Noting the above, it appears better to wait for a concrete use case
before choosing to permit extension programs to replace exception
callbacks.
As a precaution, we disable fentry and fexit for exception callbacks as
well.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-13-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Now that bpf_throw kfunc is the first such call instruction that has
noreturn semantics within the verifier, this also kicks in dead code
elimination in unprecedented ways. For one, any instruction following
a bpf_throw call will never be marked as seen. Moreover, if a callchain
ends up throwing, any instructions after the call instruction to the
eventually throwing subprog in callers will also never be marked as
seen.
The tempting way to fix this would be to emit extra 'int3' instructions
which bump the jited_len of a program, and ensure that during runtime
when a program throws, we can discover its boundaries even if the call
instruction to bpf_throw (or to subprogs that always throw) is emitted
as the final instruction in the program.
An example of such a program would be this:
do_something():
...
r0 = 0
exit
foo():
r1 = 0
call bpf_throw
r0 = 0
exit
bar(cond):
if r1 != 0 goto pc+2
call do_something
exit
call foo
r0 = 0 // Never seen by verifier
exit //
main(ctx):
r1 = ...
call bar
r0 = 0
exit
Here, if we do end up throwing, the stacktrace would be the following:
bpf_throw
foo
bar
main
In bar, the final instruction emitted will be the call to foo, as such,
the return address will be the subsequent instruction (which the JIT
emits as int3 on x86). This will end up lying outside the jited_len of
the program, thus, when unwinding, we will fail to discover the return
address as belonging to any program and end up in a panic due to the
unreliable stack unwinding of BPF programs that we never expect.
To remedy this case, make bpf_prog_ksym_find treat IP == ksym.end as
part of the BPF program, so that is_bpf_text_address returns true when
such a case occurs, and we are able to unwind reliably when the final
instruction ends up being a call instruction.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-12-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In case of the default exception callback, change the behavior of
bpf_throw, where the passed cookie value is no longer ignored, but
is instead the return value of the default exception callback. As
such, we need to place restrictions on the value being passed into
bpf_throw in such a case, only allowing those permitted by the
check_return_code function.
Thus, bpf_throw can now control the return value of the program from
each call site without having the user install a custom exception
callback just to override the return value when an exception is thrown.
We also modify the hidden subprog instructions to now move BPF_REG_1 to
BPF_REG_0, so as to set the return value before exit in the default
callback.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-9-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Since exception callbacks are not referenced using bpf_pseudo_func and
bpf_pseudo_call instructions, check_cfg traversal will never explore
instructions of the exception callback. Even after adding the subprog,
the program will then fail with a 'unreachable insn' error.
We thus need to begin walking from the start of the exception callback
again in check_cfg after a complete CFG traversal finishes, so as to
explore the CFG rooted at the exception callback.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-8-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
By default, the subprog generated by the verifier to handle a thrown
exception hardcodes a return value of 0. To allow user-defined logic
and modification of the return value when an exception is thrown,
introduce the 'exception_callback:' declaration tag, which marks a
callback as the default exception handler for the program.
The format of the declaration tag is 'exception_callback:<value>', where
<value> is the name of the exception callback. Each main program can be
tagged using this BTF declaratiion tag to associate it with an exception
callback. In case the tag is absent, the default callback is used.
As such, the exception callback cannot be modified at runtime, only set
during verification.
Allowing modification of the callback for the current program execution
at runtime leads to issues when the programs begin to nest, as any
per-CPU state maintaing this information will have to be saved and
restored. We don't want it to stay in bpf_prog_aux as this takes a
global effect for all programs. An alternative solution is spilling
the callback pointer at a known location on the program stack on entry,
and then passing this location to bpf_throw as a parameter.
However, since exceptions are geared more towards a use case where they
are ideally never invoked, optimizing for this use case and adding to
the complexity has diminishing returns.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch splits the check_btf_info's check_btf_func check into two
separate phases. The first phase sets up the BTF and prepares
func_info, but does not perform any validation of required invariants
for subprogs just yet. This is left to the second phase, which happens
where check_btf_info executes currently, and performs the line_info and
CO-RE relocation.
The reason to perform this split is to obtain the userspace supplied
func_info information before we perform the add_subprog call, where we
would now require finding and adding subprogs that may not have a
bpf_pseudo_call or bpf_pseudo_func instruction in the program.
We require this as we want to enable userspace to supply exception
callbacks that can override the default hidden subprogram generated by
the verifier (which performs a hardcoded action). In such a case, the
exception callback may never be referenced in an instruction, but will
still be suitably annotated (by way of BTF declaration tags). For
finding this exception callback, we would require the program's BTF
information, and the supplied func_info information which maps BTF type
IDs to subprograms.
Since the exception callback won't actually be referenced through
instructions, later checks in check_cfg and do_check_subprogs will not
verify the subprog. This means that add_subprog needs to add them in the
add_subprog_and_kfunc phase before we move forward, which is why the BTF
and func_info are required at that point.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch implements BPF exceptions, and introduces a bpf_throw kfunc
to allow programs to throw exceptions during their execution at runtime.
A bpf_throw invocation is treated as an immediate termination of the
program, returning back to its caller within the kernel, unwinding all
stack frames.
This allows the program to simplify its implementation, by testing for
runtime conditions which the verifier has no visibility into, and assert
that they are true. In case they are not, the program can simply throw
an exception from the other branch.
BPF exceptions are explicitly *NOT* an unlikely slowpath error handling
primitive, and this objective has guided design choices of the
implementation of the them within the kernel (with the bulk of the cost
for unwinding the stack offloaded to the bpf_throw kfunc).
The implementation of this mechanism requires use of add_hidden_subprog
mechanism introduced in the previous patch, which generates a couple of
instructions to move R1 to R0 and exit. The JIT then rewrites the
prologue of this subprog to take the stack pointer and frame pointer as
inputs and reset the stack frame, popping all callee-saved registers
saved by the main subprog. The bpf_throw function then walks the stack
at runtime, and invokes this exception subprog with the stack and frame
pointers as parameters.
Reviewers must take note that currently the main program is made to save
all callee-saved registers on x86_64 during entry into the program. This
is because we must do an equivalent of a lightweight context switch when
unwinding the stack, therefore we need the callee-saved registers of the
caller of the BPF program to be able to return with a sane state.
Note that we have to additionally handle r12, even though it is not used
by the program, because when throwing the exception the program makes an
entry into the kernel which could clobber r12 after saving it on the
stack. To be able to preserve the value we received on program entry, we
push r12 and restore it from the generated subprogram when unwinding the
stack.
For now, bpf_throw invocation fails when lingering resources or locks
exist in that path of the program. In a future followup, bpf_throw will
be extended to perform frame-by-frame unwinding to release lingering
resources for each stack frame, removing this limitation.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introduce support in the verifier for generating a subprogram and
include it as part of a BPF program dynamically after the do_check phase
is complete. The first user will be the next patch which generates
default exception callbacks if none are set for the program. The phase
of invocation will be do_misc_fixups. Note that this is an internal
verifier function, and should be used with instruction blocks which
uphold the invariants stated in check_subprogs.
Since these subprogs are always appended to the end of the instruction
sequence of the program, it becomes relatively inexpensive to do the
related adjustments to the subprog_info of the program. Only the fake
exit subprogram is shifted forward, making room for our new subprog.
This is useful to insert a new subprogram, get it JITed, and obtain its
function pointer. The next patch will use this functionality to insert a
default exception callback which will be invoked after unwinding the
stack.
Note that these added subprograms are invisible to userspace, and never
reported in BPF_OBJ_GET_INFO_BY_ID etc. For now, only a single
subprogram is supported, but more can be easily supported in the future.
To this end, two function counts are introduced now, the existing
func_cnt, and real_func_cnt, the latter including hidden programs. This
allows us to conver the JIT code to use the real_func_cnt for management
of resources while syscall path continues working with existing
func_cnt.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The plumbing for offline unwinding when we throw an exception in
programs would require walking the stack, hence introduce a new
arch_bpf_stack_walk function. This is provided when the JIT supports
exceptions, i.e. bpf_jit_supports_exceptions is true. The arch-specific
code is really minimal, hence it should be straightforward to extend
this support to other architectures as well, as it reuses the logic of
arch_stack_walk, but allowing access to unwind_state data.
Once the stack pointer and frame pointer are known for the main subprog
during the unwinding, we know the stack layout and location of any
callee-saved registers which must be restored before we return back to
the kernel. This handling will be added in the subsequent patches.
Note that while we primarily unwind through BPF frames, which are
effectively CONFIG_UNWINDER_FRAME_POINTER, we still need one of this or
CONFIG_UNWINDER_ORC to be able to unwind through the bpf_throw frame
from which we begin walking the stack. We also require both sp and bp
(stack and frame pointers) from the unwind_state structure, which are
only available when one of these two options are enabled.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Alexei Starovoitov says:
====================
The following pull-request contains BPF updates for your *net* tree.
We've added 21 non-merge commits during the last 8 day(s) which contain
a total of 21 files changed, 450 insertions(+), 36 deletions(-).
The main changes are:
1) Adjust bpf_mem_alloc buckets to match ksize(), from Hou Tao.
2) Check whether override is allowed in kprobe mult, from Jiri Olsa.
3) Fix btf_id symbol generation with ld.lld, from Jiri and Nick.
4) Fix potential deadlock when using queue and stack maps from NMI, from Toke Høiland-Jørgensen.
Please consider pulling these changes from:
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
Thanks a lot!
Also thanks to reporters, reviewers and testers of commits in this pull-request:
Alan Maguire, Biju Das, Björn Töpel, Dan Carpenter, Daniel Borkmann,
Eduard Zingerman, Hsin-Wei Hung, Marcus Seyfarth, Nathan Chancellor,
Satya Durga Srinivasu Prabhala, Song Liu, Stephen Rothwell
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
There is no fundamental reason, why multi-buffer XDP and XDP kfunc RX hints
cannot coexist in a single program.
Allow those features to be used together by modifying the flags condition
for dev-bound-only programs, segments are still prohibited for fully
offloaded programs, hence additional check.
Suggested-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/CAKH8qBuzgtJj=OKMdsxEkyML36VsAuZpcrsXcyqjdKXSJCBq=Q@mail.gmail.com/
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230915083914.65538-1-larysa.zaremba@intel.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Add new xdp-rx-metadata-features member to netdev netlink
which exports a bitmask of supported kfuncs. Most of the patch
is autogenerated (headers), the only relevant part is netdev.yaml
and the changes in netdev-genl.c to marshal into netlink.
Example output on veth:
$ ip link add veth0 type veth peer name veth1 # ifndex == 12
$ ./tools/net/ynl/samples/netdev 12
Select ifc ($ifindex; or 0 = dump; or -2 ntf check): 12
veth1[12] xdp-features (23): basic redirect rx-sg xdp-rx-metadata-features (3): timestamp hash xdp-zc-max-segs=0
Cc: netdev@vger.kernel.org
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230913171350.369987-3-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
No functional changes.
Instead of having hand-crafted code in bpf_dev_bound_resolve_kfunc,
move kfunc <> xmo handler relationship into XDP_METADATA_KFUNC_xxx.
This way, any time new kfunc is added, we don't have to touch
bpf_dev_bound_resolve_kfunc.
Also document XDP_METADATA_KFUNC_xxx arguments since we now have
more than two and it might be confusing what is what.
Cc: netdev@vger.kernel.org
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230913171350.369987-2-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Current code charges modmem for regular trampoline, but not for struct_ops
trampoline. Add bpf_jit_[charge|uncharge]_modmem() to struct_ops so the
trampoline is charged in both cases.
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230914222542.2986059-1-song@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Fix missing or extra function parameter kernel-doc warnings
in cgroup.c:
kernel/bpf/cgroup.c:1359: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_skb'
kernel/bpf/cgroup.c:1359: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_skb'
kernel/bpf/cgroup.c:1439: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_sk'
kernel/bpf/cgroup.c:1439: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_sk'
kernel/bpf/cgroup.c:1467: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_sock_addr'
kernel/bpf/cgroup.c:1467: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_sock_addr'
kernel/bpf/cgroup.c:1512: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_sock_ops'
kernel/bpf/cgroup.c:1512: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_sock_ops'
kernel/bpf/cgroup.c:1685: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_sysctl'
kernel/bpf/cgroup.c:1685: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_sysctl'
kernel/bpf/cgroup.c:795: warning: Excess function parameter 'type' description in '__cgroup_bpf_replace'
kernel/bpf/cgroup.c:795: warning: Function parameter or member 'new_prog' not described in '__cgroup_bpf_replace'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230912060812.1715-1-rdunlap@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
From commit ebf7d1f508 ("bpf, x64: rework pro/epilogue and tailcall
handling in JIT"), the tailcall on x64 works better than before.
From commit e411901c0b ("bpf: allow for tailcalls in BPF subprograms
for x64 JIT"), tailcall is able to run in BPF subprograms on x64.
From commit 5b92a28aae ("bpf: Support attaching tracing BPF program
to other BPF programs"), BPF program is able to trace other BPF programs.
How about combining them all together?
1. FENTRY/FEXIT on a BPF subprogram.
2. A tailcall runs in the BPF subprogram.
3. The tailcall calls the subprogram's caller.
As a result, a tailcall infinite loop comes up. And the loop would halt
the machine.
As we know, in tail call context, the tail_call_cnt propagates by stack
and rax register between BPF subprograms. So do in trampolines.
Fixes: ebf7d1f508 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT")
Fixes: e411901c0b ("bpf: allow for tailcalls in BPF subprograms for x64 JIT")
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>
Link: https://lore.kernel.org/r/20230912150442.2009-3-hffilwlqm@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Fix for a bug observable under the following sequence of events:
1. Create a network device that does not support XDP offload.
2. Load a device bound XDP program with BPF_F_XDP_DEV_BOUND_ONLY flag
(such programs are not offloaded).
3. Load a device bound XDP program with zero flags
(such programs are offloaded).
At step (2) __bpf_prog_dev_bound_init() associates with device (1)
a dummy bpf_offload_netdev struct with .offdev field set to NULL.
At step (3) __bpf_prog_dev_bound_init() would reuse dummy struct
allocated at step (2).
However, downstream usage of the bpf_offload_netdev assumes that
.offdev field can't be NULL, e.g. in bpf_prog_offload_verifier_prep().
Adjust __bpf_prog_dev_bound_init() to require bpf_offload_netdev
with non-NULL .offdev for offloaded BPF programs.
Fixes: 2b3486bc2d ("bpf: Introduce device-bound XDP programs")
Reported-by: syzbot+291100dcb32190ec02a8@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/000000000000d97f3c060479c4f8@google.com/
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230912005539.2248244-2-eddyz87@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Sysbot discovered that the queue and stack maps can deadlock if they are
being used from a BPF program that can be called from NMI context (such as
one that is attached to a perf HW counter event). To fix this, add an
in_nmi() check and use raw_spin_trylock() in NMI context, erroring out if
grabbing the lock fails.
Fixes: f1a2e44a3a ("bpf: add queue and stack maps")
Reported-by: Hsin-Wei Hung <hsinweih@uci.edu>
Tested-by: Hsin-Wei Hung <hsinweih@uci.edu>
Co-developed-by: Hsin-Wei Hung <hsinweih@uci.edu>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20230911132815.717240-1-toke@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add extra check in bpf_mem_alloc_init() to ensure the unit_size of
bpf_mem_cache is matched with the object_size of underlying slab cache.
If these two sizes are unmatched, print a warning once and return
-EINVAL in bpf_mem_alloc_init(), so the mismatch can be found early and
the potential issue can be prevented.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230908133923.2675053-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When the unit_size of a bpf_mem_cache is unmatched with the object_size
of the underlying slab cache, the bpf_mem_cache will not be used, and
the allocation will be redirected to a bpf_mem_cache with a bigger
unit_size instead, so there is no need to prefill for these
unused bpf_mem_caches.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230908133923.2675053-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The following warning was reported when running "./test_progs -a
link_api -a linked_list" on a RISC-V QEMU VM:
------------[ cut here ]------------
WARNING: CPU: 3 PID: 261 at kernel/bpf/memalloc.c:342 bpf_mem_refill
Modules linked in: bpf_testmod(OE)
CPU: 3 PID: 261 Comm: test_progs- ... 6.5.0-rc5-01743-gdcb152bb8328 #2
Hardware name: riscv-virtio,qemu (DT)
epc : bpf_mem_refill+0x1fc/0x206
ra : irq_work_single+0x68/0x70
epc : ffffffff801b1bc4 ra : ffffffff8015fe84 sp : ff2000000001be20
gp : ffffffff82d26138 tp : ff6000008477a800 t0 : 0000000000046600
t1 : ffffffff812b6ddc t2 : 0000000000000000 s0 : ff2000000001be70
s1 : ff5ffffffffe8998 a0 : ff5ffffffffe8998 a1 : ff600003fef4b000
a2 : 000000000000003f a3 : ffffffff80008250 a4 : 0000000000000060
a5 : 0000000000000080 a6 : 0000000000000000 a7 : 0000000000735049
s2 : ff5ffffffffe8998 s3 : 0000000000000022 s4 : 0000000000001000
s5 : 0000000000000007 s6 : ff5ffffffffe8570 s7 : ffffffff82d6bd30
s8 : 000000000000003f s9 : ffffffff82d2c5e8 s10: 000000000000ffff
s11: ffffffff82d2c5d8 t3 : ffffffff81ea8f28 t4 : 0000000000000000
t5 : ff6000008fd28278 t6 : 0000000000040000
[<ffffffff801b1bc4>] bpf_mem_refill+0x1fc/0x206
[<ffffffff8015fe84>] irq_work_single+0x68/0x70
[<ffffffff8015feb4>] irq_work_run_list+0x28/0x36
[<ffffffff8015fefa>] irq_work_run+0x38/0x66
[<ffffffff8000828a>] handle_IPI+0x3a/0xb4
[<ffffffff800a5c3a>] handle_percpu_devid_irq+0xa4/0x1f8
[<ffffffff8009fafa>] generic_handle_domain_irq+0x28/0x36
[<ffffffff800ae570>] ipi_mux_process+0xac/0xfa
[<ffffffff8000a8ea>] sbi_ipi_handle+0x2e/0x88
[<ffffffff8009fafa>] generic_handle_domain_irq+0x28/0x36
[<ffffffff807ee70e>] riscv_intc_irq+0x36/0x4e
[<ffffffff812b5d3a>] handle_riscv_irq+0x54/0x86
[<ffffffff812b6904>] do_irq+0x66/0x98
---[ end trace 0000000000000000 ]---
The warning is due to WARN_ON_ONCE(tgt->unit_size != c->unit_size) in
free_bulk(). The direct reason is that a object is allocated and
freed by bpf_mem_caches with different unit_size.
The root cause is that KMALLOC_MIN_SIZE is 64 and there is no 96-bytes
slab cache in the specific VM. When linked_list test allocates a
72-bytes object through bpf_obj_new(), bpf_global_ma will allocate it
from a bpf_mem_cache with 96-bytes unit_size, but this bpf_mem_cache is
backed by 128-bytes slab cache. When the object is freed, bpf_mem_free()
uses ksize() to choose the corresponding bpf_mem_cache. Because the
object is allocated from 128-bytes slab cache, ksize() returns 128,
bpf_mem_free() chooses a 128-bytes bpf_mem_cache to free the object and
triggers the warning.
A similar warning will also be reported when using CONFIG_SLAB instead
of CONFIG_SLUB in a x86-64 kernel. Because CONFIG_SLUB defines
KMALLOC_MIN_SIZE as 8 but CONFIG_SLAB defines KMALLOC_MIN_SIZE as 32.
An alternative fix is to use kmalloc_size_round() in bpf_mem_alloc() to
choose a bpf_mem_cache which has the same unit_size with the backing
slab cache, but it may introduce performance degradation, so fix the
warning by adjusting the indexes in size_index according to the value of
KMALLOC_MIN_SIZE just like setup_kmalloc_cache_index_table() does.
Fixes: 822fb26bdb ("bpf: Add a hint to allocated objects.")
Reported-by: Björn Töpel <bjorn@kernel.org>
Closes: https://lore.kernel.org/bpf/87jztjmmy4.fsf@all.your.base.are.belong.to.us
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230908133923.2675053-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
* The kernel now dynamically probes for misaligned access speed, as
opposed to relying on a table of known implementations.
* Support for non-coherent devices on systems using the Andes AX45MP
core, including the RZ/Five SoCs.
* Support for the V extension in ptrace(), again.
* Support for KASLR.
* Support for the BPF prog pack allocator in RISC-V.
* A handful of bug fixes and cleanups.
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Merge tag 'riscv-for-linus-6.6-mw2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull more RISC-V updates from Palmer Dabbelt:
- The kernel now dynamically probes for misaligned access speed, as
opposed to relying on a table of known implementations.
- Support for non-coherent devices on systems using the Andes AX45MP
core, including the RZ/Five SoCs.
- Support for the V extension in ptrace(), again.
- Support for KASLR.
- Support for the BPF prog pack allocator in RISC-V.
- A handful of bug fixes and cleanups.
* tag 'riscv-for-linus-6.6-mw2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (25 commits)
soc: renesas: Kconfig: For ARCH_R9A07G043 select the required configs if dependencies are met
riscv: Kconfig.errata: Add dependency for RISCV_SBI in ERRATA_ANDES config
riscv: Kconfig.errata: Drop dependency for MMU in ERRATA_ANDES_CMO config
riscv: Kconfig: Select DMA_DIRECT_REMAP only if MMU is enabled
bpf, riscv: use prog pack allocator in the BPF JIT
riscv: implement a memset like function for text
riscv: extend patch_text_nosync() for multiple pages
bpf: make bpf_prog_pack allocator portable
riscv: libstub: Implement KASLR by using generic functions
libstub: Fix compilation warning for rv32
arm64: libstub: Move KASLR handling functions to kaslr.c
riscv: Dump out kernel offset information on panic
riscv: Introduce virtual kernel mapping KASLR
RISC-V: Add ptrace support for vectors
soc: renesas: Kconfig: Select the required configs for RZ/Five SoC
cache: Add L2 cache management for Andes AX45MP RISC-V core
dt-bindings: cache: andestech,ax45mp-cache: Add DT binding documentation for L2 cache controller
riscv: mm: dma-noncoherent: nonstandard cache operations support
riscv: errata: Add Andes alternative ports
riscv: asm: vendorid_list: Add Andes Technology to the vendors list
...
Puranjay Mohan <puranjay12@gmail.com> says:
Here is some data to prove the V2 fixes the problem:
Without this series:
root@rv-selftester:~/src/kselftest/bpf# time ./test_tag
test_tag: OK (40945 tests)
real 7m47.562s
user 0m24.145s
sys 6m37.064s
With this series applied:
root@rv-selftester:~/src/selftest/bpf# time ./test_tag
test_tag: OK (40945 tests)
real 7m29.472s
user 0m25.865s
sys 6m18.401s
BPF programs currently consume a page each on RISCV. For systems with many BPF
programs, this adds significant pressure to instruction TLB. High iTLB pressure
usually causes slow down for the whole system.
Song Liu introduced the BPF prog pack allocator[1] to mitigate the above issue.
It packs multiple BPF programs into a single huge page. It is currently only
enabled for the x86_64 BPF JIT.
I enabled this allocator on the ARM64 BPF JIT[2]. It is being reviewed now.
This patch series enables the BPF prog pack allocator for the RISCV BPF JIT.
======================================================
Performance Analysis of prog pack allocator on RISCV64
======================================================
Test setup:
===========
Host machine: Debian GNU/Linux 11 (bullseye)
Qemu Version: QEMU emulator version 8.0.3 (Debian 1:8.0.3+dfsg-1)
u-boot-qemu Version: 2023.07+dfsg-1
opensbi Version: 1.3-1
To test the performance of the BPF prog pack allocator on RV, a stresser
tool[4] linked below was built. This tool loads 8 BPF programs on the system and
triggers 5 of them in an infinite loop by doing system calls.
The runner script starts 20 instances of the above which loads 8*20=160 BPF
programs on the system, 5*20=100 of which are being constantly triggered.
The script is passed a command which would be run in the above environment.
The script was run with following perf command:
./run.sh "perf stat -a \
-e iTLB-load-misses \
-e dTLB-load-misses \
-e dTLB-store-misses \
-e instructions \
--timeout 60000"
The output of the above command is discussed below before and after enabling the
BPF prog pack allocator.
The tests were run on qemu-system-riscv64 with 8 cpus, 16G memory. The rootfs
was created using Bjorn's riscv-cross-builder[5] docker container linked below.
Results
=======
Before enabling prog pack allocator:
------------------------------------
Performance counter stats for 'system wide':
4939048 iTLB-load-misses
5468689 dTLB-load-misses
465234 dTLB-store-misses
1441082097998 instructions
60.045791200 seconds time elapsed
After enabling prog pack allocator:
-----------------------------------
Performance counter stats for 'system wide':
3430035 iTLB-load-misses
5008745 dTLB-load-misses
409944 dTLB-store-misses
1441535637988 instructions
60.046296600 seconds time elapsed
Improvements in metrics
=======================
It was expected that the iTLB-load-misses would decrease as now a single huge
page is used to keep all the BPF programs compared to a single page for each
program earlier.
--------------------------------------------
The improvement in iTLB-load-misses: -30.5 %
--------------------------------------------
I repeated this expriment more than 100 times in different setups and the
improvement was always greater than 30%.
This patch series is boot tested on the Starfive VisionFive 2 board[6].
The performance analysis was not done on the board because it doesn't
expose iTLB-load-misses, etc. The stresser program was run on the board to test
the loading and unloading of BPF programs
[1] https://lore.kernel.org/bpf/20220204185742.271030-1-song@kernel.org/
[2] https://lore.kernel.org/all/20230626085811.3192402-1-puranjay12@gmail.com/
[3] https://lore.kernel.org/all/20230626085811.3192402-2-puranjay12@gmail.com/
[4] https://github.com/puranjaymohan/BPF-Allocator-Bench
[5] https://github.com/bjoto/riscv-cross-builder
[6] https://www.starfivetech.com/en/site/boards
* b4-shazam-merge:
bpf, riscv: use prog pack allocator in the BPF JIT
riscv: implement a memset like function for text
riscv: extend patch_text_nosync() for multiple pages
bpf: make bpf_prog_pack allocator portable
Link: https://lore.kernel.org/r/20230831131229.497941-1-puranjay12@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Kill saved_tid. It looks ugly to update *tid and then restore the
previous value if __task_pid_nr_ns() returns 0. Change this code
to update *tid and common->pid_visiting once before return.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154656.GA24950@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
It only adds the unnecessary confusion and compicates the "retry" code.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154654.GA24945@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Unless I am notally confused it is wrong. We are going to return or
skip next_task so we need to check next_task-files, not task->files.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154651.GA24940@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
get_pid_task() makes no sense, the code does put_task_struct() soon after.
Use find_task_by_pid_ns() instead of find_pid_ns + get_pid_task and kill
put_task_struct(), this allows to do get_task_struct() only once before
return.
While at it, kill the unnecessary "if (!pid)" check in the "if (!*tid)"
block, this matches the next usage of find_pid_ns() + get_pid_task() in
this function.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154649.GA24935@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
1. find_pid_ns() + get_pid_task() under rcu_read_lock() guarantees that we
can safely iterate the task->thread_group list. Even if this task exits
right after get_pid_task() (or goto retry) and pid_alive() returns 0.
Kill the unnecessary pid_alive() check.
2. next_thread() simply can't return NULL, kill the bogus "if (!next_task)"
check.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154646.GA24928@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Both unit_free() and unit_free_rcu() invoke irq_work_raise() to free
freed objects back to slab and the invocation may also be preempted by
unit_alloc() and unit_alloc() may return NULL unexpectedly as shown in
the following case:
task A task B
unit_free()
// high_watermark = 48
// free_cnt = 49 after free
irq_work_raise()
// mark irq work as IRQ_WORK_PENDING
irq_work_claim()
// task B preempts task A
unit_alloc()
// free_cnt = 48 after alloc
// does unit_alloc() 32-times
......
// free_cnt = 16
unit_alloc()
// free_cnt = 15 after alloc
// irq work is already PENDING,
// so just return
irq_work_raise()
// does unit_alloc() 15-times
......
// free_cnt = 0
unit_alloc()
// free_cnt = 0 before alloc
return NULL
Fix it by enabling IRQ after irq_work_raise() completes.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230901111954.1804721-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When doing stress test for qp-trie, bpf_mem_alloc() returned NULL
unexpectedly because all qp-trie operations were initiated from
bpf syscalls and there was still available free memory. bpf_obj_new()
has the same problem as shown by the following selftest.
The failure is due to the preemption. irq_work_raise() will invoke
irq_work_claim() first to mark the irq work as pending and then inovke
__irq_work_queue_local() to raise an IPI. So when the current task
which is invoking irq_work_raise() is preempted by other task,
unit_alloc() may return NULL for preemption task as shown below:
task A task B
unit_alloc()
// low_watermark = 32
// free_cnt = 31 after alloc
irq_work_raise()
// mark irq work as IRQ_WORK_PENDING
irq_work_claim()
// task B preempts task A
unit_alloc()
// free_cnt = 30 after alloc
// irq work is already PENDING,
// so just return
irq_work_raise()
// does unit_alloc() 30-times
......
unit_alloc()
// free_cnt = 0 before alloc
return NULL
Fix it by enabling IRQ after irq_work_raise() completes. An alternative
fix is using preempt_{disable|enable}_notrace() pair, but it may have
extra overhead. Another feasible fix is to only disable preemption or
IRQ before invoking irq_work_queue() and enable preemption or IRQ after
the invocation completes, but it can't handle the case when
c->low_watermark is 1.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230901111954.1804721-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In previous selftests/bpf patch, we have
p = bpf_percpu_obj_new(struct val_t);
if (!p)
goto out;
p1 = bpf_kptr_xchg(&e->pc, p);
if (p1) {
/* race condition */
bpf_percpu_obj_drop(p1);
}
p = e->pc;
if (!p)
goto out;
After bpf_kptr_xchg(), we need to re-read e->pc into 'p'.
This is due to that the second argument of bpf_kptr_xchg() is marked
OBJ_RELEASE and it will be marked as invalid after the call.
So after bpf_kptr_xchg(), 'p' is an unknown scalar,
and the bpf program needs to reread from the map value.
This patch checks if the 'p' has type MEM_ALLOC and MEM_PERCPU,
and if 'p' is RCU protected. If this is the case, 'p' can be marked
as MEM_RCU. MEM_ALLOC needs to be removed since 'p' is not
an owning reference any more. Such a change makes re-read
from the map value unnecessary.
Note that re-reading 'e->pc' after bpf_kptr_xchg() might get
a different value from 'p' if immediately before 'p = e->pc',
another cpu may do another bpf_kptr_xchg() and swap in another value
into 'e->pc'. If this is the case, then 'p = e->pc' may
get either 'p' or another value, and race condition already exists.
So removing direct re-reading seems fine too.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230827152816.2000760-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The bpf helpers bpf_this_cpu_ptr() and bpf_per_cpu_ptr() are re-purposed
for allocated percpu objects. For an allocated percpu obj,
the reg type is 'PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU'.
The return type for these two re-purposed helpera is
'PTR_TO_MEM | MEM_RCU | MEM_ALLOC'.
The MEM_ALLOC allows that the per-cpu data can be read and written.
Since the memory allocator bpf_mem_alloc() returns
a ptr to a percpu ptr for percpu data, the first argument
of bpf_this_cpu_ptr() and bpf_per_cpu_ptr() is patched
with a dereference before passing to the helper func.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230827152749.1997202-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add two new kfunc's, bpf_percpu_obj_new_impl() and
bpf_percpu_obj_drop_impl(), to allocate a percpu obj.
Two functions are very similar to bpf_obj_new_impl()
and bpf_obj_drop_impl(). The major difference is related
to percpu handling.
bpf_rcu_read_lock()
struct val_t __percpu_kptr *v = map_val->percpu_data;
...
bpf_rcu_read_unlock()
For a percpu data map_val like above 'v', the reg->type
is set as
PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU
if inside rcu critical section.
MEM_RCU marking here is similar to NON_OWN_REF as 'v'
is not a owning reference. But NON_OWN_REF is
trusted and typically inside the spinlock while
MEM_RCU is under rcu read lock. RCU is preferred here
since percpu data structures mean potential concurrent
access into its contents.
Also, bpf_percpu_obj_new_impl() is restricted such that
no pointers or special fields are allowed. Therefore,
the bpf_list_head and bpf_rb_root will not be supported
in this patch set to avoid potential memory leak issue
due to racing between bpf_obj_free_fields() and another
bpf_kptr_xchg() moving an allocated object to
bpf_list_head and bpf_rb_root.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230827152744.1996739-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF_KPTR_PERCPU represents a percpu field type like below
struct val_t {
... fields ...
};
struct t {
...
struct val_t __percpu_kptr *percpu_data_ptr;
...
};
where
#define __percpu_kptr __attribute__((btf_type_tag("percpu_kptr")))
While BPF_KPTR_REF points to a trusted kernel object or a trusted
local object, BPF_KPTR_PERCPU points to a trusted local
percpu object.
This patch added basic support for BPF_KPTR_PERCPU
related to percpu_kptr field parsing, recording and free operations.
BPF_KPTR_PERCPU also supports the same map types
as BPF_KPTR_REF does.
Note that unlike a local kptr, it is possible that
a BPF_KTPR_PERCPU struct may not contain any
special fields like other kptr, bpf_spin_lock, bpf_list_head, etc.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230827152739.1996391-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This is needed for later percpu mem allocation when the
allocation is done by bpf program. For such cases, a global
bpf_global_percpu_ma is added where a flexible allocation
size is needed.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230827152734.1995725-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Current release - regressions:
- eth: stmmac: fix failure to probe without MAC interface specified
Current release - new code bugs:
- docs: netlink: fix missing classic_netlink doc reference
Previous releases - regressions:
- deal with integer overflows in kmalloc_reserve()
- use sk_forward_alloc_get() in sk_get_meminfo()
- bpf_sk_storage: fix the missing uncharge in sk_omem_alloc
- fib: avoid warn splat in flow dissector after packet mangling
- skb_segment: call zero copy functions before using skbuff frags
- eth: sfc: check for zero length in EF10 RX prefix
Previous releases - always broken:
- af_unix: fix msg_controllen test in scm_pidfd_recv() for
MSG_CMSG_COMPAT
- xsk: fix xsk_build_skb() dereferencing possible ERR_PTR()
- netfilter:
- nft_exthdr: fix non-linear header modification
- xt_u32, xt_sctp: validate user space input
- nftables: exthdr: fix 4-byte stack OOB write
- nfnetlink_osf: avoid OOB read
- one more fix for the garbage collection work from last release
- igmp: limit igmpv3_newpack() packet size to IP_MAX_MTU
- bpf, sockmap: fix preempt_rt splat when using raw_spin_lock_t
- handshake: fix null-deref in handshake_nl_done_doit()
- ip: ignore dst hint for multipath routes to ensure packets
are hashed across the nexthops
- phy: micrel:
- correct bit assignments for cable test errata
- disable EEE according to the KSZ9477 errata
Misc:
- docs/bpf: document compile-once-run-everywhere (CO-RE) relocations
- Revert "net: macsec: preserve ingress frame ordering", it appears
to have been developed against an older kernel, problem doesn't
exist upstream
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking updates from Jakub Kicinski:
"Including fixes from netfilter and bpf.
Current release - regressions:
- eth: stmmac: fix failure to probe without MAC interface specified
Current release - new code bugs:
- docs: netlink: fix missing classic_netlink doc reference
Previous releases - regressions:
- deal with integer overflows in kmalloc_reserve()
- use sk_forward_alloc_get() in sk_get_meminfo()
- bpf_sk_storage: fix the missing uncharge in sk_omem_alloc
- fib: avoid warn splat in flow dissector after packet mangling
- skb_segment: call zero copy functions before using skbuff frags
- eth: sfc: check for zero length in EF10 RX prefix
Previous releases - always broken:
- af_unix: fix msg_controllen test in scm_pidfd_recv() for
MSG_CMSG_COMPAT
- xsk: fix xsk_build_skb() dereferencing possible ERR_PTR()
- netfilter:
- nft_exthdr: fix non-linear header modification
- xt_u32, xt_sctp: validate user space input
- nftables: exthdr: fix 4-byte stack OOB write
- nfnetlink_osf: avoid OOB read
- one more fix for the garbage collection work from last release
- igmp: limit igmpv3_newpack() packet size to IP_MAX_MTU
- bpf, sockmap: fix preempt_rt splat when using raw_spin_lock_t
- handshake: fix null-deref in handshake_nl_done_doit()
- ip: ignore dst hint for multipath routes to ensure packets are
hashed across the nexthops
- phy: micrel:
- correct bit assignments for cable test errata
- disable EEE according to the KSZ9477 errata
Misc:
- docs/bpf: document compile-once-run-everywhere (CO-RE) relocations
- Revert "net: macsec: preserve ingress frame ordering", it appears
to have been developed against an older kernel, problem doesn't
exist upstream"
* tag 'net-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (95 commits)
net: enetc: distinguish error from valid pointers in enetc_fixup_clear_rss_rfs()
Revert "net: team: do not use dynamic lockdep key"
net: hns3: remove GSO partial feature bit
net: hns3: fix the port information display when sfp is absent
net: hns3: fix invalid mutex between tc qdisc and dcb ets command issue
net: hns3: fix debugfs concurrency issue between kfree buffer and read
net: hns3: fix byte order conversion issue in hclge_dbg_fd_tcam_read()
net: hns3: Support query tx timeout threshold by debugfs
net: hns3: fix tx timeout issue
net: phy: Provide Module 4 KSZ9477 errata (DS80000754C)
netfilter: nf_tables: Unbreak audit log reset
netfilter: ipset: add the missing IP_SET_HASH_WITH_NET0 macro for ip_set_hash_netportnet.c
netfilter: nft_set_rbtree: skip sync GC for new elements in this transaction
netfilter: nf_tables: uapi: Describe NFTA_RULE_CHAIN_ID
netfilter: nfnetlink_osf: avoid OOB read
netfilter: nftables: exthdr: fix 4-byte stack OOB write
selftests/bpf: Check bpf_sk_storage has uncharged sk_omem_alloc
bpf: bpf_sk_storage: Fix the missing uncharge in sk_omem_alloc
bpf: bpf_sk_storage: Fix invalid wait context lockdep report
s390/bpf: Pass through tail call counter in trampolines
...
The bpf_prog_pack allocator currently uses module_alloc() and
module_memfree() to allocate and free memory. This is not portable
because different architectures use different methods for allocating
memory for BPF programs. Like ARM64 and riscv use vmalloc()/vfree().
Use bpf_jit_alloc_exec() and bpf_jit_free_exec() for memory management
in bpf_prog_pack allocator. Other architectures can override these with
their implementation and will be able to use bpf_prog_pack directly.
On architectures that don't override bpf_jit_alloc/free_exec() this is
basically a NOP.
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20230831131229.497941-2-puranjay12@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The commit c83597fa5d ("bpf: Refactor some inode/task/sk storage functions
for reuse"), refactored the bpf_{sk,task,inode}_storage_free() into
bpf_local_storage_unlink_nolock() which then later renamed to
bpf_local_storage_destroy(). The commit accidentally passed the
"bool uncharge_mem = false" argument to bpf_selem_unlink_storage_nolock()
which then stopped the uncharge from happening to the sk->sk_omem_alloc.
This missing uncharge only happens when the sk is going away (during
__sk_destruct).
This patch fixes it by always passing "uncharge_mem = true". It is a
noop to the task/inode/cgroup storage because they do not have the
map_local_storage_(un)charge enabled in the map_ops. A followup patch
will be done in bpf-next to remove the uncharge_mem argument.
A selftest is added in the next patch.
Fixes: c83597fa5d ("bpf: Refactor some inode/task/sk storage functions for reuse")
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230901231129.578493-3-martin.lau@linux.dev
'./test_progs -t test_local_storage' reported a splat:
[ 27.137569] =============================
[ 27.138122] [ BUG: Invalid wait context ]
[ 27.138650] 6.5.0-03980-gd11ae1b16b0a #247 Tainted: G O
[ 27.139542] -----------------------------
[ 27.140106] test_progs/1729 is trying to lock:
[ 27.140713] ffff8883ef047b88 (stock_lock){-.-.}-{3:3}, at: local_lock_acquire+0x9/0x130
[ 27.141834] other info that might help us debug this:
[ 27.142437] context-{5:5}
[ 27.142856] 2 locks held by test_progs/1729:
[ 27.143352] #0: ffffffff84bcd9c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x4/0x40
[ 27.144492] #1: ffff888107deb2c0 (&storage->lock){..-.}-{2:2}, at: bpf_local_storage_update+0x39e/0x8e0
[ 27.145855] stack backtrace:
[ 27.146274] CPU: 0 PID: 1729 Comm: test_progs Tainted: G O 6.5.0-03980-gd11ae1b16b0a #247
[ 27.147550] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 27.149127] Call Trace:
[ 27.149490] <TASK>
[ 27.149867] dump_stack_lvl+0x130/0x1d0
[ 27.152609] dump_stack+0x14/0x20
[ 27.153131] __lock_acquire+0x1657/0x2220
[ 27.153677] lock_acquire+0x1b8/0x510
[ 27.157908] local_lock_acquire+0x29/0x130
[ 27.159048] obj_cgroup_charge+0xf4/0x3c0
[ 27.160794] slab_pre_alloc_hook+0x28e/0x2b0
[ 27.161931] __kmem_cache_alloc_node+0x51/0x210
[ 27.163557] __kmalloc+0xaa/0x210
[ 27.164593] bpf_map_kzalloc+0xbc/0x170
[ 27.165147] bpf_selem_alloc+0x130/0x510
[ 27.166295] bpf_local_storage_update+0x5aa/0x8e0
[ 27.167042] bpf_fd_sk_storage_update_elem+0xdb/0x1a0
[ 27.169199] bpf_map_update_value+0x415/0x4f0
[ 27.169871] map_update_elem+0x413/0x550
[ 27.170330] __sys_bpf+0x5e9/0x640
[ 27.174065] __x64_sys_bpf+0x80/0x90
[ 27.174568] do_syscall_64+0x48/0xa0
[ 27.175201] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 27.175932] RIP: 0033:0x7effb40e41ad
[ 27.176357] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d8
[ 27.179028] RSP: 002b:00007ffe64c21fc8 EFLAGS: 00000202 ORIG_RAX: 0000000000000141
[ 27.180088] RAX: ffffffffffffffda RBX: 00007ffe64c22768 RCX: 00007effb40e41ad
[ 27.181082] RDX: 0000000000000020 RSI: 00007ffe64c22008 RDI: 0000000000000002
[ 27.182030] RBP: 00007ffe64c21ff0 R08: 0000000000000000 R09: 00007ffe64c22788
[ 27.183038] R10: 0000000000000064 R11: 0000000000000202 R12: 0000000000000000
[ 27.184006] R13: 00007ffe64c22788 R14: 00007effb42a1000 R15: 0000000000000000
[ 27.184958] </TASK>
It complains about acquiring a local_lock while holding a raw_spin_lock.
It means it should not allocate memory while holding a raw_spin_lock
since it is not safe for RT.
raw_spin_lock is needed because bpf_local_storage supports tracing
context. In particular for task local storage, it is easy to
get a "current" task PTR_TO_BTF_ID in tracing bpf prog.
However, task (and cgroup) local storage has already been moved to
bpf mem allocator which can be used after raw_spin_lock.
The splat is for the sk storage. For sk (and inode) storage,
it has not been moved to bpf mem allocator. Using raw_spin_lock or not,
kzalloc(GFP_ATOMIC) could theoretically be unsafe in tracing context.
However, the local storage helper requires a verifier accepted
sk pointer (PTR_TO_BTF_ID), it is hypothetical if that (mean running
a bpf prog in a kzalloc unsafe context and also able to hold a verifier
accepted sk pointer) could happen.
This patch avoids kzalloc after raw_spin_lock to silent the splat.
There is an existing kzalloc before the raw_spin_lock. At that point,
a kzalloc is very likely required because a lookup has just been done
before. Thus, this patch always does the kzalloc before acquiring
the raw_spin_lock and remove the later kzalloc usage after the
raw_spin_lock. After this change, it will have a charge and then
uncharge during the syscall bpf_map_update_elem() code path.
This patch opts for simplicity and not continue the old
optimization to save one charge and uncharge.
This issue is dated back to the very first commit of bpf_sk_storage
which had been refactored multiple times to create task, inode, and
cgroup storage. This patch uses a Fixes tag with a more recent
commit that should be easier to do backport.
Fixes: b00fa38a9c ("bpf: Enable non-atomic allocations in local storage")
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230901231129.578493-2-martin.lau@linux.dev
__bpf_prog_enter_recur() assigns bpf_tramp_run_ctx::saved_run_ctx before
performing the recursion check which means in case of a recursion
__bpf_prog_exit_recur() uses the previously set bpf_tramp_run_ctx::saved_run_ctx
value.
__bpf_prog_enter_sleepable_recur() assigns bpf_tramp_run_ctx::saved_run_ctx
after the recursion check which means in case of a recursion
__bpf_prog_exit_sleepable_recur() uses an uninitialized value. This does not
look right. If I read the entry trampoline code right, then bpf_tramp_run_ctx
isn't initialized upfront.
Align __bpf_prog_enter_sleepable_recur() with __bpf_prog_enter_recur() and
set bpf_tramp_run_ctx::saved_run_ctx before the recursion check is made.
Remove the assignment of saved_run_ctx in kern_sys_bpf() since it happens
a few cycles later.
Fixes: e384c7b7b4 ("bpf, x86: Create bpf_tramp_run_ctx on the caller thread's stack")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20230830080405.251926-3-bigeasy@linutronix.de
If __bpf_prog_enter_sleepable_recur() detects recursion then it returns
0 without undoing rcu_read_lock_trace(), migrate_disable() or
decrementing the recursion counter. This is fine in the JIT case because
the JIT code will jump in the 0 case to the end and invoke the matching
exit trampoline (__bpf_prog_exit_sleepable_recur()).
This is not the case in kern_sys_bpf() which returns directly to the
caller with an error code.
Add __bpf_prog_exit_sleepable_recur() as clean up in the recursion case.
Fixes: b1d18a7574 ("bpf: Extend sys_bpf commands for bpf_syscall programs.")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20230830080405.251926-2-bigeasy@linutronix.de
- kprobes: use struct_size() for variable size kretprobe_instance
data structure.
- eprobe: Simplify trace_eprobe list iteration.
- probe events: Data structure field access support on BTF argument.
. Update BTF argument support on the functions in the kernel loadable
modules (only loaded modules are supported).
. Move generic BTF access function (search function prototype and get
function parameters) to a separated file.
. Add a function to search a member of data structure in BTF.
. Support accessing BTF data structure member from probe args by
C-like arrow('->') and dot('.') operators. e.g.
't sched_switch next=next->pid vruntime=next->se.vruntime'
. Support accessing BTF data structure member from $retval. e.g.
'f getname_flags%return +0($retval->name):string'
. Add string type checking if BTF type info is available.
This will reject if user specify ":string" type for non "char
pointer" type.
. Automatically assume the fprobe event as a function return event
if $retval is used.
- selftests/ftrace: Add BTF data field access test cases.
- Documentation: Update fprobe event example with BTF data field.
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Merge tag 'probes-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull probes updates from Masami Hiramatsu:
- kprobes: use struct_size() for variable size kretprobe_instance data
structure.
- eprobe: Simplify trace_eprobe list iteration.
- probe events: Data structure field access support on BTF argument.
- Update BTF argument support on the functions in the kernel
loadable modules (only loaded modules are supported).
- Move generic BTF access function (search function prototype and
get function parameters) to a separated file.
- Add a function to search a member of data structure in BTF.
- Support accessing BTF data structure member from probe args by
C-like arrow('->') and dot('.') operators. e.g.
't sched_switch next=next->pid vruntime=next->se.vruntime'
- Support accessing BTF data structure member from $retval. e.g.
'f getname_flags%return +0($retval->name):string'
- Add string type checking if BTF type info is available. This will
reject if user specify ":string" type for non "char pointer"
type.
- Automatically assume the fprobe event as a function return event
if $retval is used.
- selftests/ftrace: Add BTF data field access test cases.
- Documentation: Update fprobe event example with BTF data field.
* tag 'probes-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
Documentation: tracing: Update fprobe event example with BTF field
selftests/ftrace: Add BTF fields access testcases
tracing/fprobe-event: Assume fprobe is a return event by $retval
tracing/probes: Add string type check with BTF
tracing/probes: Support BTF field access from $retval
tracing/probes: Support BTF based data structure field access
tracing/probes: Add a function to search a member of a struct/union
tracing/probes: Move finding func-proto API and getting func-param API to trace_btf
tracing/probes: Support BTF argument on module functions
tracing/eprobe: Iterate trace_eprobe directly
kernel: kprobes: Use struct_size()
Core
----
- Increase size limits for to-be-sent skb frag allocations. This
allows tun, tap devices and packet sockets to better cope with large
writes operations.
- Store netdevs in an xarray, to simplify iterating over netdevs.
- Refactor nexthop selection for multipath routes.
- Improve sched class lifetime handling.
- Add backup nexthop ID support for bridge.
- Implement drop reasons support in openvswitch.
- Several data races annotations and fixes.
- Constify the sk parameter of routing functions.
- Prepend kernel version to netconsole message.
Protocols
---------
- Implement support for TCP probing the peer being under memory
pressure.
- Remove hard coded limitation on IPv6 specific info placement
inside the socket struct.
- Get rid of sysctl_tcp_adv_win_scale and use an auto-estimated
per socket scaling factor.
- Scaling-up the IPv6 expired route GC via a separated list of
expiring routes.
- In-kernel support for the TLS alert protocol.
- Better support for UDP reuseport with connected sockets.
- Add NEXT-C-SID support for SRv6 End.X behavior, reducing the SR
header size.
- Get rid of additional ancillary per MPTCP connection struct socket.
- Implement support for BPF-based MPTCP packet schedulers.
- Format MPTCP subtests selftests results in TAP.
- Several new SMC 2.1 features including unique experimental options,
max connections per lgr negotiation, max links per lgr negotiation.
BPF
---
- Multi-buffer support in AF_XDP.
- Add multi uprobe BPF links for attaching multiple uprobes
and usdt probes, which is significantly faster and saves extra fds.
- Implement an fd-based tc BPF attach API (TCX) and BPF link support on
top of it.
- Add SO_REUSEPORT support for TC bpf_sk_assign.
- Support new instructions from cpu v4 to simplify the generated code and
feature completeness, for x86, arm64, riscv64.
- Support defragmenting IPv(4|6) packets in BPF.
- Teach verifier actual bounds of bpf_get_smp_processor_id()
and fix perf+libbpf issue related to custom section handling.
- Introduce bpf map element count and enable it for all program types.
- Add a BPF hook in sys_socket() to change the protocol ID
from IPPROTO_TCP to IPPROTO_MPTCP to cover migration for legacy.
- Introduce bpf_me_mcache_free_rcu() and fix OOM under stress.
- Add uprobe support for the bpf_get_func_ip helper.
- Check skb ownership against full socket.
- Support for up to 12 arguments in BPF trampoline.
- Extend link_info for kprobe_multi and perf_event links.
Netfilter
---------
- Speed-up process exit by aborting ruleset validation if a
fatal signal is pending.
- Allow NLA_POLICY_MASK to be used with BE16/BE32 types.
Driver API
----------
- Page pool optimizations, to improve data locality and cache usage.
- Introduce ndo_hwtstamp_get() and ndo_hwtstamp_set() to avoid the need
for raw ioctl() handling in drivers.
- Simplify genetlink dump operations (doit/dumpit) providing them
the common information already populated in struct genl_info.
- Extend and use the yaml devlink specs to [re]generate the split ops.
- Introduce devlink selective dumps, to allow SF filtering SF based on
handle and other attributes.
- Add yaml netlink spec for netlink-raw families, allow route, link and
address related queries via the ynl tool.
- Remove phylink legacy mode support.
- Support offload LED blinking to phy.
- Add devlink port function attributes for IPsec.
New hardware / drivers
----------------------
- Ethernet:
- Broadcom ASP 2.0 (72165) ethernet controller
- MediaTek MT7988 SoC
- Texas Instruments AM654 SoC
- Texas Instruments IEP driver
- Atheros qca8081 phy
- Marvell 88Q2110 phy
- NXP TJA1120 phy
- WiFi:
- MediaTek mt7981 support
- Can:
- Kvaser SmartFusion2 PCI Express devices
- Allwinner T113 controllers
- Texas Instruments tcan4552/4553 chips
- Bluetooth:
- Intel Gale Peak
- Qualcomm WCN3988 and WCN7850
- NXP AW693 and IW624
- Mediatek MT2925
Drivers
-------
- Ethernet NICs:
- nVidia/Mellanox:
- mlx5:
- support UDP encapsulation in packet offload mode
- IPsec packet offload support in eswitch mode
- improve aRFS observability by adding new set of counters
- extends MACsec offload support to cover RoCE traffic
- dynamic completion EQs
- mlx4:
- convert to use auxiliary bus instead of custom interface logic
- Intel
- ice:
- implement switchdev bridge offload, even for LAG interfaces
- implement SRIOV support for LAG interfaces
- igc:
- add support for multiple in-flight TX timestamps
- Broadcom:
- bnxt:
- use the unified RX page pool buffers for XDP and non-XDP
- use the NAPI skb allocation cache
- OcteonTX2:
- support Round Robin scheduling HTB offload
- TC flower offload support for SPI field
- Freescale:
- add XDP_TX feature support
- AMD:
- ionic: add support for PCI FLR event
- sfc:
- basic conntrack offload
- introduce eth, ipv4 and ipv6 pedit offloads
- ST Microelectronics:
- stmmac: maximze PTP timestamping resolution
- Virtual NICs:
- Microsoft vNIC:
- batch ringing RX queue doorbell on receiving packets
- add page pool for RX buffers
- Virtio vNIC:
- add per queue interrupt coalescing support
- Google vNIC:
- add queue-page-list mode support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add port range matching tc-flower offload
- permit enslavement to netdevices with uppers
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- convert to phylink_pcs
- Renesas:
- r8A779fx: add speed change support
- rzn1: enables vlan support
- Ethernet PHYs:
- convert mv88e6xxx to phylink_pcs
- WiFi:
- Qualcomm Wi-Fi 7 (ath12k):
- extremely High Throughput (EHT) PHY support
- RealTek (rtl8xxxu):
- enable AP mode for: RTL8192FU, RTL8710BU (RTL8188GU),
RTL8192EU and RTL8723BU
- RealTek (rtw89):
- Introduce Time Averaged SAR (TAS) support
- Connector:
- support for event filtering
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Merge tag 'net-next-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Paolo Abeni:
"Core:
- Increase size limits for to-be-sent skb frag allocations. This
allows tun, tap devices and packet sockets to better cope with
large writes operations
- Store netdevs in an xarray, to simplify iterating over netdevs
- Refactor nexthop selection for multipath routes
- Improve sched class lifetime handling
- Add backup nexthop ID support for bridge
- Implement drop reasons support in openvswitch
- Several data races annotations and fixes
- Constify the sk parameter of routing functions
- Prepend kernel version to netconsole message
Protocols:
- Implement support for TCP probing the peer being under memory
pressure
- Remove hard coded limitation on IPv6 specific info placement inside
the socket struct
- Get rid of sysctl_tcp_adv_win_scale and use an auto-estimated per
socket scaling factor
- Scaling-up the IPv6 expired route GC via a separated list of
expiring routes
- In-kernel support for the TLS alert protocol
- Better support for UDP reuseport with connected sockets
- Add NEXT-C-SID support for SRv6 End.X behavior, reducing the SR
header size
- Get rid of additional ancillary per MPTCP connection struct socket
- Implement support for BPF-based MPTCP packet schedulers
- Format MPTCP subtests selftests results in TAP
- Several new SMC 2.1 features including unique experimental options,
max connections per lgr negotiation, max links per lgr negotiation
BPF:
- Multi-buffer support in AF_XDP
- Add multi uprobe BPF links for attaching multiple uprobes and usdt
probes, which is significantly faster and saves extra fds
- Implement an fd-based tc BPF attach API (TCX) and BPF link support
on top of it
- Add SO_REUSEPORT support for TC bpf_sk_assign
- Support new instructions from cpu v4 to simplify the generated code
and feature completeness, for x86, arm64, riscv64
- Support defragmenting IPv(4|6) packets in BPF
- Teach verifier actual bounds of bpf_get_smp_processor_id() and fix
perf+libbpf issue related to custom section handling
- Introduce bpf map element count and enable it for all program types
- Add a BPF hook in sys_socket() to change the protocol ID from
IPPROTO_TCP to IPPROTO_MPTCP to cover migration for legacy
- Introduce bpf_me_mcache_free_rcu() and fix OOM under stress
- Add uprobe support for the bpf_get_func_ip helper
- Check skb ownership against full socket
- Support for up to 12 arguments in BPF trampoline
- Extend link_info for kprobe_multi and perf_event links
Netfilter:
- Speed-up process exit by aborting ruleset validation if a fatal
signal is pending
- Allow NLA_POLICY_MASK to be used with BE16/BE32 types
Driver API:
- Page pool optimizations, to improve data locality and cache usage
- Introduce ndo_hwtstamp_get() and ndo_hwtstamp_set() to avoid the
need for raw ioctl() handling in drivers
- Simplify genetlink dump operations (doit/dumpit) providing them the
common information already populated in struct genl_info
- Extend and use the yaml devlink specs to [re]generate the split ops
- Introduce devlink selective dumps, to allow SF filtering SF based
on handle and other attributes
- Add yaml netlink spec for netlink-raw families, allow route, link
and address related queries via the ynl tool
- Remove phylink legacy mode support
- Support offload LED blinking to phy
- Add devlink port function attributes for IPsec
New hardware / drivers:
- Ethernet:
- Broadcom ASP 2.0 (72165) ethernet controller
- MediaTek MT7988 SoC
- Texas Instruments AM654 SoC
- Texas Instruments IEP driver
- Atheros qca8081 phy
- Marvell 88Q2110 phy
- NXP TJA1120 phy
- WiFi:
- MediaTek mt7981 support
- Can:
- Kvaser SmartFusion2 PCI Express devices
- Allwinner T113 controllers
- Texas Instruments tcan4552/4553 chips
- Bluetooth:
- Intel Gale Peak
- Qualcomm WCN3988 and WCN7850
- NXP AW693 and IW624
- Mediatek MT2925
Drivers:
- Ethernet NICs:
- nVidia/Mellanox:
- mlx5:
- support UDP encapsulation in packet offload mode
- IPsec packet offload support in eswitch mode
- improve aRFS observability by adding new set of counters
- extends MACsec offload support to cover RoCE traffic
- dynamic completion EQs
- mlx4:
- convert to use auxiliary bus instead of custom interface
logic
- Intel
- ice:
- implement switchdev bridge offload, even for LAG
interfaces
- implement SRIOV support for LAG interfaces
- igc:
- add support for multiple in-flight TX timestamps
- Broadcom:
- bnxt:
- use the unified RX page pool buffers for XDP and non-XDP
- use the NAPI skb allocation cache
- OcteonTX2:
- support Round Robin scheduling HTB offload
- TC flower offload support for SPI field
- Freescale:
- add XDP_TX feature support
- AMD:
- ionic: add support for PCI FLR event
- sfc:
- basic conntrack offload
- introduce eth, ipv4 and ipv6 pedit offloads
- ST Microelectronics:
- stmmac: maximze PTP timestamping resolution
- Virtual NICs:
- Microsoft vNIC:
- batch ringing RX queue doorbell on receiving packets
- add page pool for RX buffers
- Virtio vNIC:
- add per queue interrupt coalescing support
- Google vNIC:
- add queue-page-list mode support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add port range matching tc-flower offload
- permit enslavement to netdevices with uppers
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- convert to phylink_pcs
- Renesas:
- r8A779fx: add speed change support
- rzn1: enables vlan support
- Ethernet PHYs:
- convert mv88e6xxx to phylink_pcs
- WiFi:
- Qualcomm Wi-Fi 7 (ath12k):
- extremely High Throughput (EHT) PHY support
- RealTek (rtl8xxxu):
- enable AP mode for: RTL8192FU, RTL8710BU (RTL8188GU),
RTL8192EU and RTL8723BU
- RealTek (rtw89):
- Introduce Time Averaged SAR (TAS) support
- Connector:
- support for event filtering"
* tag 'net-next-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1806 commits)
net: ethernet: mtk_wed: minor change in wed_{tx,rx}info_show
net: ethernet: mtk_wed: add some more info in wed_txinfo_show handler
net: stmmac: clarify difference between "interface" and "phy_interface"
r8152: add vendor/device ID pair for D-Link DUB-E250
devlink: move devlink_notify_register/unregister() to dev.c
devlink: move small_ops definition into netlink.c
devlink: move tracepoint definitions into core.c
devlink: push linecard related code into separate file
devlink: push rate related code into separate file
devlink: push trap related code into separate file
devlink: use tracepoint_enabled() helper
devlink: push region related code into separate file
devlink: push param related code into separate file
devlink: push resource related code into separate file
devlink: push dpipe related code into separate file
devlink: move and rename devlink_dpipe_send_and_alloc_skb() helper
devlink: push shared buffer related code into separate file
devlink: push port related code into separate file
devlink: push object register/unregister notifications into separate helpers
inet: fix IP_TRANSPARENT error handling
...
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Merge tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs timestamp updates from Christian Brauner:
"This adds VFS support for multi-grain timestamps and converts tmpfs,
xfs, ext4, and btrfs to use them. This carries acks from all relevant
filesystems.
The VFS always uses coarse-grained timestamps when updating the ctime
and mtime after a change. This has the benefit of allowing filesystems
to optimize away a lot of metadata updates, down to around 1 per
jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide to invalidate the cache.
Even with NFSv4, a lot of exported filesystems don't properly support
a change attribute and are subject to the same problems with timestamp
granularity. Other applications have similar issues with timestamps
(e.g., backup applications).
If we were to always use fine-grained timestamps, that would improve
the situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.
This introduces fine-grained timestamps that are used when they are
actively queried.
This uses the 31st bit of the ctime tv_nsec field to indicate that
something has queried the inode for the mtime or ctime. When this flag
is set, on the next mtime or ctime update, the kernel will fetch a
fine-grained timestamp instead of the usual coarse-grained one.
As POSIX generally mandates that when the mtime changes, the ctime
must also change the kernel always stores normalized ctime values, so
only the first 30 bits of the tv_nsec field are ever used.
Filesytems can opt into this behavior by setting the FS_MGTIME flag in
the fstype. Filesystems that don't set this flag will continue to use
coarse-grained timestamps.
Various preparatory changes, fixes and cleanups are included:
- Fixup all relevant places where POSIX requires updating ctime
together with mtime. This is a wide-range of places and all
maintainers provided necessary Acks.
- Add new accessors for inode->i_ctime directly and change all
callers to rely on them. Plain accesses to inode->i_ctime are now
gone and it is accordingly rename to inode->__i_ctime and commented
as requiring accessors.
- Extend generic_fillattr() to pass in a request mask mirroring in a
sense the statx() uapi. This allows callers to pass in a request
mask to only get a subset of attributes filled in.
- Rework timestamp updates so it's possible to drop the @now
parameter the update_time() inode operation and associated helpers.
- Add inode_update_timestamps() and convert all filesystems to it
removing a bunch of open-coding"
* tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (107 commits)
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
tmpfs: add support for multigrain timestamps
fs: add infrastructure for multigrain timestamps
fs: drop the timespec64 argument from update_time
xfs: have xfs_vn_update_time gets its own timestamp
fat: make fat_update_time get its own timestamp
fat: remove i_version handling from fat_update_time
ubifs: have ubifs_update_time use inode_update_timestamps
btrfs: have it use inode_update_timestamps
fs: drop the timespec64 arg from generic_update_time
fs: pass the request_mask to generic_fillattr
fs: remove silly warning from current_time
gfs2: fix timestamp handling on quota inodes
fs: rename i_ctime field to __i_ctime
selinux: convert to ctime accessor functions
security: convert to ctime accessor functions
apparmor: convert to ctime accessor functions
sunrpc: convert to ctime accessor functions
...
Commit 9e7a4d9831 ("bpf: Allow LSM programs to use bpf spin locks")
disabled bpf_spin_lock usage in sleepable progs, stating:
Sleepable LSM programs can be preempted which means that allowng spin
locks will need more work (disabling preemption and the verifier
ensuring that no sleepable helpers are called when a spin lock is
held).
This patch disables preemption before grabbing bpf_spin_lock. The second
requirement above "no sleepable helpers are called when a spin lock is
held" is implicitly enforced by current verifier logic due to helper
calls in spin_lock CS being disabled except for a few exceptions, none
of which sleep.
Due to above preemption changes, bpf_spin_lock CS can also be considered
a RCU CS, so verifier's in_rcu_cs check is modified to account for this.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230821193311.3290257-7-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
An earlier patch in the series ensures that the underlying memory of
nodes with bpf_refcount - which can have multiple owners - is not reused
until RCU grace period has elapsed. This prevents
use-after-free with non-owning references that may point to
recently-freed memory. While RCU read lock is held, it's safe to
dereference such a non-owning ref, as by definition RCU GP couldn't have
elapsed and therefore underlying memory couldn't have been reused.
From the perspective of verifier "trustedness" non-owning refs to
refcounted nodes are now trusted only in RCU CS and therefore should no
longer pass is_trusted_reg, but rather is_rcu_reg. Let's mark them
MEM_RCU in order to reflect this new state.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230821193311.3290257-6-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Now that all reported issues are fixed, bpf_refcount_acquire can be
turned back on. Also reenable all bpf_refcount-related tests which were
disabled.
This a revert of:
* commit f3514a5d67 ("selftests/bpf: Disable newly-added 'owner' field test until refcount re-enabled")
* commit 7deca5eae8 ("bpf: Disable bpf_refcount_acquire kfunc calls until race conditions are fixed")
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230821193311.3290257-5-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This is the final fix for the use-after-free scenario described in
commit 7793fc3bab ("bpf: Make bpf_refcount_acquire fallible for
non-owning refs"). That commit, by virtue of changing
bpf_refcount_acquire's refcount_inc to a refcount_inc_not_zero, fixed
the "refcount incr on 0" splat. The not_zero check in
refcount_inc_not_zero, though, still occurs on memory that could have
been free'd and reused, so the commit didn't properly fix the root
cause.
This patch actually fixes the issue by free'ing using the recently-added
bpf_mem_free_rcu, which ensures that the memory is not reused until
RCU grace period has elapsed. If that has happened then
there are no non-owning references alive that point to the
recently-free'd memory, so it can be safely reused.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230821193311.3290257-4-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
It's straightforward to prove that kptr_struct_meta must be non-NULL for
any valid call to these kfuncs:
* btf_parse_struct_metas in btf.c creates a btf_struct_meta for any
struct in user BTF with a special field (e.g. bpf_refcount,
{rb,list}_node). These are stored in that BTF's struct_meta_tab.
* __process_kf_arg_ptr_to_graph_node in verifier.c ensures that nodes
have {rb,list}_node field and that it's at the correct offset.
Similarly, check_kfunc_args ensures bpf_refcount field existence for
node param to bpf_refcount_acquire.
* So a btf_struct_meta must have been created for the struct type of
node param to these kfuncs
* That BTF and its struct_meta_tab are guaranteed to still be around.
Any arbitrary {rb,list} node the BPF program interacts with either:
came from bpf_obj_new or a collection removal kfunc in the same
program, in which case the BTF is associated with the program and
still around; or came from bpf_kptr_xchg, in which case the BTF was
associated with the map and is still around
Instead of silently continuing with NULL struct_meta, which caused
confusing bugs such as those addressed by commit 2140a6e342 ("bpf: Set
kptr_struct_meta for node param to list and rbtree insert funcs"), let's
error out. Then, at runtime, we can confidently say that the
implementations of these kfuncs were given a non-NULL kptr_struct_meta,
meaning that special-field-specific functionality like
bpf_obj_free_fields and the bpf_obj_drop change introduced later in this
series are guaranteed to execute.
This patch doesn't change functionality, just makes it easier to reason
about existing functionality.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230821193311.3290257-2-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, in function bpf_obj_free_fields(), for local kptr,
a warning will be issued if the struct does not contain any
special fields. But actually the kernel seems totally okay
with a local kptr without any special fields. Permitting
no special fields also aligns with future percpu kptr which
also allows no special fields.
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230824063417.201925-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
After we converted the capabilities of our networking-bpf program from
cap_sys_admin to cap_net_admin+cap_bpf, our networking-bpf program
failed to start. Because it failed the bpf verifier, and the error log
is "R3 pointer comparison prohibited".
A simple reproducer as follows,
SEC("cls-ingress")
int ingress(struct __sk_buff *skb)
{
struct iphdr *iph = (void *)(long)skb->data + sizeof(struct ethhdr);
if ((long)(iph + 1) > (long)skb->data_end)
return TC_ACT_STOLEN;
return TC_ACT_OK;
}
Per discussion with Yonghong and Alexei [1], comparison of two packet
pointers is not a pointer leak. This patch fixes it.
Our local kernel is 6.1.y and we expect this fix to be backported to
6.1.y, so stable is CCed.
[1]. https://lore.kernel.org/bpf/CAADnVQ+Nmspr7Si+pxWn8zkE7hX-7s93ugwC+94aXSy4uQ9vBg@mail.gmail.com/
Suggested-by: Yonghong Song <yonghong.song@linux.dev>
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230823020703.3790-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Since the btf returned from bpf_get_btf_vmlinux() only covers functions in
the vmlinux, BTF argument is not available on the functions in the modules.
Use bpf_find_btf_id() instead of bpf_get_btf_vmlinux()+btf_find_name_kind()
so that BTF argument can find the correct struct btf and btf_type in it.
With this fix, fprobe events can use `$arg*` on module functions as below
# grep nf_log_ip_packet /proc/kallsyms
ffffffffa0005c00 t nf_log_ip_packet [nf_log_syslog]
ffffffffa0005bf0 t __pfx_nf_log_ip_packet [nf_log_syslog]
# echo 'f nf_log_ip_packet $arg*' > dynamic_events
# cat dynamic_events
f:fprobes/nf_log_ip_packet__entry nf_log_ip_packet net=net pf=pf hooknum=hooknum skb=skb in=in out=out loginfo=loginfo prefix=prefix
To support the module's btf which is removable, the struct btf needs to be
ref-counted. So this also records the btf in the traceprobe_parse_context
and returns the refcount when the parse has done.
Link: https://lore.kernel.org/all/169272154223.160970.3507930084247934031.stgit@devnote2/
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The commit being fixed introduced a hunk into check_func_arg_reg_off
that bypasses reg->off == 0 enforcement when offset points to a graph
node or root. This might possibly be done for treating bpf_rbtree_remove
and others as KF_RELEASE and then later check correct reg->off in helper
argument checks.
But this is not the case, those helpers are already not KF_RELEASE and
permit non-zero reg->off and verify it later to match the subobject in
BTF type.
However, this logic leads to bpf_obj_drop permitting free of register
arguments with non-zero offset when they point to a graph root or node
within them, which is not ok.
For instance:
struct foo {
int i;
int j;
struct bpf_rb_node node;
};
struct foo *f = bpf_obj_new(typeof(*f));
if (!f) ...
bpf_obj_drop(f); // OK
bpf_obj_drop(&f->i); // still ok from verifier PoV
bpf_obj_drop(&f->node); // Not OK, but permitted right now
Fix this by dropping the whole part of code altogether.
Fixes: 6a3cd3318f ("bpf: Migrate release_on_unlock logic to non-owning ref semantics")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230822175140.1317749-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When reviewing local percpu kptr support, Alexei discovered a bug
wherea bpf_kptr_xchg() may succeed even if the map value kptr type and
locally allocated obj type do not match ([1]). Missed struct btf_id
comparison is the reason for the bug. This patch added such struct btf_id
comparison and will flag verification failure if types do not match.
[1] https://lore.kernel.org/bpf/20230819002907.io3iphmnuk43xblu@macbook-pro-8.dhcp.thefacebook.com/#t
Reported-by: Alexei Starovoitov <ast@kernel.org>
Fixes: 738c96d5e2 ("bpf: Allow local kptrs to be exchanged via bpf_kptr_xchg")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230822050053.2886960-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Adding support to specify pid for uprobe_multi link and the uprobes
are created only for task with given pid value.
Using the consumer.filter filter callback for that, so the task gets
filtered during the uprobe installation.
We still need to check the task during runtime in the uprobe handler,
because the handler could get executed if there's another system
wide consumer on the same uprobe (thanks Oleg for the insight).
Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230809083440.3209381-6-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Adding support to specify cookies array for uprobe_multi link.
The cookies array share indexes and length with other uprobe_multi
arrays (offsets/ref_ctr_offsets).
The cookies[i] value defines cookie for i-the uprobe and will be
returned by bpf_get_attach_cookie helper when called from ebpf
program hooked to that specific uprobe.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230809083440.3209381-5-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Adding new multi uprobe link that allows to attach bpf program
to multiple uprobes.
Uprobes to attach are specified via new link_create uprobe_multi
union:
struct {
__aligned_u64 path;
__aligned_u64 offsets;
__aligned_u64 ref_ctr_offsets;
__u32 cnt;
__u32 flags;
} uprobe_multi;
Uprobes are defined for single binary specified in path and multiple
calling sites specified in offsets array with optional reference
counters specified in ref_ctr_offsets array. All specified arrays
have length of 'cnt'.
The 'flags' supports single bit for now that marks the uprobe as
return probe.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230809083440.3209381-4-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
After synchronous_rcu(), both the dettached XDP program and
xdp_do_flush() are completed, and the only user of bpf_cpu_map_entry
will be cpu_map_kthread_run(), so instead of calling
__cpu_map_entry_replace() to stop kthread and cleanup entry after a RCU
grace period, do these things directly.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20230816045959.358059-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
As for now __cpu_map_entry_replace() uses call_rcu() to wait for the
inflight xdp program to exit the RCU read critical section, and then
launch kworker cpu_map_kthread_stop() to call kthread_stop() to flush
all pending xdp frames or skbs.
But it is unnecessary to use rcu_barrier() in cpu_map_kthread_stop() to
wait for the completion of __cpu_map_entry_free(), because rcu_barrier()
will wait for all pending RCU callbacks and cpu_map_kthread_stop() only
needs to wait for the completion of a specific __cpu_map_entry_free().
So use queue_rcu_work() to replace call_rcu(), schedule_work() and
rcu_barrier(). queue_rcu_work() will queue a __cpu_map_entry_free()
kworker after a RCU grace period. Because __cpu_map_entry_free() is
running in a kworker context, so it is OK to do all of these freeing
procedures include kthread_stop() in it.
After the update, there is no need to do reference-counting for
bpf_cpu_map_entry, because bpf_cpu_map_entry is freed directly in
__cpu_map_entry_free(), so just remove it.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20230816045959.358059-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The commit 1b715e1b0e ("bpf: Support ->fill_link_info for perf_event") leads
to the following Smatch static checker warning:
kernel/bpf/syscall.c:3416 bpf_perf_link_fill_kprobe()
error: uninitialized symbol 'type'.
That can happens when uname is NULL. So fix it by verifying the uname when we
really need to fill it.
Fixes: 1b715e1b0e ("bpf: Support ->fill_link_info for perf_event")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Closes: https://lore.kernel.org/bpf/85697a7e-f897-4f74-8b43-82721bebc462@kili.mountain
Link: https://lore.kernel.org/bpf/20230813141900.1268-2-laoar.shao@gmail.com
Currently, if a struct_ops map is loaded with BPF_F_LINK, it must also
define the .validate() and .update() callbacks in its corresponding
struct bpf_struct_ops in the kernel. Enabling struct_ops link is useful
in its own right to ensure that the map is unloaded if an application
crashes. For example, with sched_ext, we want to automatically unload
the host-wide scheduler if the application crashes. We would likely
never support updating elements of a sched_ext struct_ops map, so we'd
have to implement these callbacks showing that they _can't_ support
element updates just to benefit from the basic lifetime management of
struct_ops links.
Let's enable struct_ops maps to work with BPF_F_LINK even if they
haven't defined these callbacks, by assuming that a struct_ops map
element cannot be updated by default.
Acked-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230814185908.700553-2-void@manifault.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
syzbot reports a verifier bug which triggers a runtime panic.
The test bpf program is:
0: (62) *(u32 *)(r10 -8) = 553656332
1: (bf) r1 = (s16)r10
2: (07) r1 += -8
3: (b7) r2 = 3
4: (bd) if r2 <= r1 goto pc+0
5: (85) call bpf_trace_printk#-138320
6: (b7) r0 = 0
7: (95) exit
At insn 1, the current implementation keeps 'r1' as a frame pointer,
which caused later bpf_trace_printk helper call crash since frame
pointer address is not valid any more. Note that at insn 4,
the 'pointer vs. scalar' comparison is allowed for privileged
prog run.
To fix the problem with above insn 1, the fix in the patch adopts
similar pattern to existing 'R1 = (u32) R2' handling. For unprivileged
prog run, verification will fail with 'R<num> sign-extension part of pointer'.
For privileged prog run, the dst_reg 'r1' will be marked as
an unknown scalar, so later 'bpf_trace_pointk' helper will complain
since it expected certain pointers.
Reported-by: syzbot+d61b595e9205573133b3@syzkaller.appspotmail.com
Fixes: 8100928c88 ("bpf: Support new sign-extension mov insns")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230807175721.671696-1-yonghong.song@linux.dev
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Verify if the pointer obtained from bpf_xdp_pointer() is either an error or
NULL before returning it.
The function bpf_dynptr_slice() mistakenly returned an ERR_PTR. Instead of
solely checking for NULL, it should also verify if the pointer returned by
bpf_xdp_pointer() is an error or NULL.
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/bpf/d1360219-85c3-4a03-9449-253ea905f9d1@moroto.mountain/
Fixes: 66e3a13e7c ("bpf: Add bpf_dynptr_slice and bpf_dynptr_slice_rdwr")
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230803231206.1060485-1-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
syzbot reported an UBSAN array-index-out-of-bounds access in bpf_mprog_read()
upon bpf_mprog_detach(). While it did not have a reproducer, I was able to
manually reproduce through an empty mprog entry which just has miniq present.
The latter is important given otherwise we get an ENOENT error as tcx detaches
the whole mprog entry. The index 4294967295 was triggered via NULL dtuple.prog
which then attempts to detach from the back. bpf_mprog_fetch() in this case
did hit the idx == total and therefore tried to grab the entry at idx -1.
Fix it by adding an explicit bpf_mprog_total() check in bpf_mprog_detach() and
bail out early with ENOENT.
Fixes: 053c8e1f23 ("bpf: Add generic attach/detach/query API for multi-progs")
Reported-by: syzbot+0c06ba0f831fe07a8f27@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20230804131112.11012-1-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
err and tlinks is assigned first, so it does not need to initialize the
assignment.
Signed-off-by: Li kunyu <kunyu@nfschina.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230804175929.2867-1-kunyu@nfschina.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Martin KaFai Lau says:
====================
pull-request: bpf-next 2023-08-03
We've added 54 non-merge commits during the last 10 day(s) which contain
a total of 84 files changed, 4026 insertions(+), 562 deletions(-).
The main changes are:
1) Add SO_REUSEPORT support for TC bpf_sk_assign from Lorenz Bauer,
Daniel Borkmann
2) Support new insns from cpu v4 from Yonghong Song
3) Non-atomically allocate freelist during prefill from YiFei Zhu
4) Support defragmenting IPv(4|6) packets in BPF from Daniel Xu
5) Add tracepoint to xdp attaching failure from Leon Hwang
6) struct netdev_rx_queue and xdp.h reshuffling to reduce
rebuild time from Jakub Kicinski
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (54 commits)
net: invert the netdevice.h vs xdp.h dependency
net: move struct netdev_rx_queue out of netdevice.h
eth: add missing xdp.h includes in drivers
selftests/bpf: Add testcase for xdp attaching failure tracepoint
bpf, xdp: Add tracepoint to xdp attaching failure
selftests/bpf: fix static assert compilation issue for test_cls_*.c
bpf: fix bpf_probe_read_kernel prototype mismatch
riscv, bpf: Adapt bpf trampoline to optimized riscv ftrace framework
libbpf: fix typos in Makefile
tracing: bpf: use struct trace_entry in struct syscall_tp_t
bpf, devmap: Remove unused dtab field from bpf_dtab_netdev
bpf, cpumap: Remove unused cmap field from bpf_cpu_map_entry
netfilter: bpf: Only define get_proto_defrag_hook() if necessary
bpf: Fix an array-index-out-of-bounds issue in disasm.c
net: remove duplicate INDIRECT_CALLABLE_DECLARE of udp[6]_ehashfn
docs/bpf: Fix malformed documentation
bpf: selftests: Add defrag selftests
bpf: selftests: Support custom type and proto for client sockets
bpf: selftests: Support not connecting client socket
netfilter: bpf: Support BPF_F_NETFILTER_IP_DEFRAG in netfilter link
...
====================
Link: https://lore.kernel.org/r/20230803174845.825419-1-martin.lau@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
xdp.h is far more specific and is included in only 67 other
files vs netdevice.h's 1538 include sites.
Make xdp.h include netdevice.h, instead of the other way around.
This decreases the incremental allmodconfig builds size when
xdp.h is touched from 5947 to 662 objects.
Move bpf_prog_run_xdp() to xdp.h, seems appropriate and filter.h
is a mega-header in its own right so it's nice to avoid xdp.h
getting included there as well.
The only unfortunate part is that the typedef for xdp_features_t
has to move to netdevice.h, since its embedded in struct netdevice.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://lore.kernel.org/r/20230803010230.1755386-4-kuba@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
bpf_probe_read_kernel() has a __weak definition in core.c and another
definition with an incompatible prototype in kernel/trace/bpf_trace.c,
when CONFIG_BPF_EVENTS is enabled.
Since the two are incompatible, there cannot be a shared declaration in
a header file, but the lack of a prototype causes a W=1 warning:
kernel/bpf/core.c:1638:12: error: no previous prototype for 'bpf_probe_read_kernel' [-Werror=missing-prototypes]
On 32-bit architectures, the local prototype
u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
passes arguments in other registers as the one in bpf_trace.c
BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size,
const void *, unsafe_ptr)
which uses 64-bit arguments in pairs of registers.
As both versions of the function are fairly simple and only really
differ in one line, just move them into a header file as an inline
function that does not add any overhead for the bpf_trace.c callers
and actually avoids a function call for the other one.
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/ac25cb0f-b804-1649-3afb-1dc6138c2716@iogearbox.net/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230801111449.185301-1-arnd@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit 96360004b8 ("xdp: Make devmap flush_list common for all map
instances") removes the use of bpf_dtab_netdev::dtab in bq_enqueue(),
so just remove dtab from bpf_dtab_netdev.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://lore.kernel.org/r/20230728014942.892272-3-houtao@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Since commit cdfafe98ca ("xdp: Make cpumap flush_list common for all
map instances"), cmap is no longer used, so just remove it.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230728014942.892272-2-houtao@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
syzbot reported an array-index-out-of-bounds when printing out bpf
insns. Further investigation shows the insn is illegal but
is printed out due to log level 1 or 2 before actual insn verification
in do_check().
This particular illegal insn is a MOVSX insn with offset value 2.
The legal offset value for MOVSX should be 8, 16 and 32.
The disasm sign-extension-size array index is calculated as
(insn->off / 8) - 1
and offset value 2 gives an out-of-bound index -1.
Tighten the checking for MOVSX insn in disasm.c to avoid
array-index-out-of-bounds issue.
Reported-by: syzbot+3758842a6c01012aa73b@syzkaller.appspotmail.com
Fixes: f835bb6222 ("bpf: Add kernel/bpftool asm support for new instructions")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230731204534.1975311-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The following warning was reported when running xdp_redirect_cpu with
both skb-mode and stress-mode enabled:
------------[ cut here ]------------
Incorrect XDP memory type (-2128176192) usage
WARNING: CPU: 7 PID: 1442 at net/core/xdp.c:405
Modules linked in:
CPU: 7 PID: 1442 Comm: kworker/7:0 Tainted: G 6.5.0-rc2+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Workqueue: events __cpu_map_entry_free
RIP: 0010:__xdp_return+0x1e4/0x4a0
......
Call Trace:
<TASK>
? show_regs+0x65/0x70
? __warn+0xa5/0x240
? __xdp_return+0x1e4/0x4a0
......
xdp_return_frame+0x4d/0x150
__cpu_map_entry_free+0xf9/0x230
process_one_work+0x6b0/0xb80
worker_thread+0x96/0x720
kthread+0x1a5/0x1f0
ret_from_fork+0x3a/0x70
ret_from_fork_asm+0x1b/0x30
</TASK>
The reason for the warning is twofold. One is due to the kthread
cpu_map_kthread_run() is stopped prematurely. Another one is
__cpu_map_ring_cleanup() doesn't handle skb mode and treats skbs in
ptr_ring as XDP frames.
Prematurely-stopped kthread will be fixed by the preceding patch and
ptr_ring will be empty when __cpu_map_ring_cleanup() is called. But
as the comments in __cpu_map_ring_cleanup() said, handling and freeing
skbs in ptr_ring as well to "catch any broken behaviour gracefully".
Fixes: 11941f8a85 ("bpf: cpumap: Implement generic cpumap")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://lore.kernel.org/r/20230729095107.1722450-3-houtao@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
The following warning was reported when running stress-mode enabled
xdp_redirect_cpu with some RT threads:
------------[ cut here ]------------
WARNING: CPU: 4 PID: 65 at kernel/bpf/cpumap.c:135
CPU: 4 PID: 65 Comm: kworker/4:1 Not tainted 6.5.0-rc2+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Workqueue: events cpu_map_kthread_stop
RIP: 0010:put_cpu_map_entry+0xda/0x220
......
Call Trace:
<TASK>
? show_regs+0x65/0x70
? __warn+0xa5/0x240
......
? put_cpu_map_entry+0xda/0x220
cpu_map_kthread_stop+0x41/0x60
process_one_work+0x6b0/0xb80
worker_thread+0x96/0x720
kthread+0x1a5/0x1f0
ret_from_fork+0x3a/0x70
ret_from_fork_asm+0x1b/0x30
</TASK>
The root cause is the same as commit 4369016497 ("bpf: cpumap: Fix memory
leak in cpu_map_update_elem"). The kthread is stopped prematurely by
kthread_stop() in cpu_map_kthread_stop(), and kthread() doesn't call
cpu_map_kthread_run() at all but XDP program has already queued some
frames or skbs into ptr_ring. So when __cpu_map_ring_cleanup() checks
the ptr_ring, it will find it was not emptied and report a warning.
An alternative fix is to use __cpu_map_ring_cleanup() to drop these
pending frames or skbs when kthread_stop() returns -EINTR, but it may
confuse the user, because these frames or skbs have been handled
correctly by XDP program. So instead of dropping these frames or skbs,
just make sure the per-cpu kthread is running before
__cpu_map_entry_alloc() returns.
After apply the fix, the error handle for kthread_stop() will be
unnecessary because it will always return 0, so just remove it.
Fixes: 6710e11269 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUMAP")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://lore.kernel.org/r/20230729095107.1722450-2-houtao@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
During unregister_netdevice_many_notify(), the ordering of our concerned
function calls is like this:
unregister_netdevice_many_notify
dev_shutdown
qdisc_put
clsact_destroy
tcx_uninstall
The syzbot reproducer triggered a case that the qdisc refcnt is not
zero during dev_shutdown().
tcx_uninstall() will then WARN_ON_ONCE(tcx_entry(entry)->miniq_active)
because the miniq is still active and the entry should not be freed.
The latter assumed that qdisc destruction happens before tcx teardown.
This fix is to avoid tcx_uninstall() doing tcx_entry_free() when the
miniq is still alive and let the clsact_destroy() do the free later, so
that we do not assume any specific ordering for either of them.
If still active, tcx_uninstall() does clear the entry when flushing out
the prog/link. clsact_destroy() will then notice the "!tcx_entry_is_active()"
and then does the tcx_entry_free() eventually.
Fixes: e420bed025 ("bpf: Add fd-based tcx multi-prog infra with link support")
Reported-by: syzbot+376a289e86a0fd02b9ba@syzkaller.appspotmail.com
Reported-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: syzbot+376a289e86a0fd02b9ba@syzkaller.appspotmail.com
Tested-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/222255fe07cb58f15ee662e7ee78328af5b438e4.1690549248.git.daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In internal testing of test_maps, we sometimes observed failures like:
test_maps: test_maps.c:173: void test_hashmap_percpu(unsigned int, void *):
Assertion `bpf_map_update_elem(fd, &key, value, BPF_ANY) == 0' failed.
where the errno is ENOMEM. After some troubleshooting and enabling
the warnings, we saw:
[ 91.304708] percpu: allocation failed, size=8 align=8 atomic=1, atomic alloc failed, no space left
[ 91.304716] CPU: 51 PID: 24145 Comm: test_maps Kdump: loaded Tainted: G N 6.1.38-smp-DEV #7
[ 91.304719] Hardware name: Google Astoria/astoria, BIOS 0.20230627.0-0 06/27/2023
[ 91.304721] Call Trace:
[ 91.304724] <TASK>
[ 91.304730] [<ffffffffa7ef83b9>] dump_stack_lvl+0x59/0x88
[ 91.304737] [<ffffffffa7ef83f8>] dump_stack+0x10/0x18
[ 91.304738] [<ffffffffa75caa0c>] pcpu_alloc+0x6fc/0x870
[ 91.304741] [<ffffffffa75ca302>] __alloc_percpu_gfp+0x12/0x20
[ 91.304743] [<ffffffffa756785e>] alloc_bulk+0xde/0x1e0
[ 91.304746] [<ffffffffa7566c02>] bpf_mem_alloc_init+0xd2/0x2f0
[ 91.304747] [<ffffffffa7547c69>] htab_map_alloc+0x479/0x650
[ 91.304750] [<ffffffffa751d6e0>] map_create+0x140/0x2e0
[ 91.304752] [<ffffffffa751d413>] __sys_bpf+0x5a3/0x6c0
[ 91.304753] [<ffffffffa751c3ec>] __x64_sys_bpf+0x1c/0x30
[ 91.304754] [<ffffffffa7ef847a>] do_syscall_64+0x5a/0x80
[ 91.304756] [<ffffffffa800009b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
This makes sense, because in atomic context, percpu allocation would
not create new chunks; it would only create in non-atomic contexts.
And if during prefill all precpu chunks are full, -ENOMEM would
happen immediately upon next unit_alloc.
Prefill phase does not actually run in atomic context, so we can
use this fact to allocate non-atomically with GFP_KERNEL instead
of GFP_NOWAIT. This avoids the immediate -ENOMEM.
GFP_NOWAIT has to be used in unit_alloc when bpf program runs
in atomic context. Even if bpf program runs in non-atomic context,
in most cases, rcu read lock is enabled for the program so
GFP_NOWAIT is still needed. This is often also the case for
BPF_MAP_UPDATE_ELEM syscalls.
Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230728043359.3324347-1-zhuyifei@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The kernel test robot reported compilation warnings when -Wparentheses is
added to KBUILD_CFLAGS with gcc compiler. The following is the error message:
.../bpf-next/kernel/bpf/verifier.c: In function ‘coerce_reg_to_size_sx’:
.../bpf-next/kernel/bpf/verifier.c:5901:14:
error: suggest parentheses around comparison in operand of ‘==’ [-Werror=parentheses]
if (s64_max >= 0 == s64_min >= 0) {
~~~~~~~~^~~~
.../bpf-next/kernel/bpf/verifier.c: In function ‘coerce_subreg_to_size_sx’:
.../bpf-next/kernel/bpf/verifier.c:5965:14:
error: suggest parentheses around comparison in operand of ‘==’ [-Werror=parentheses]
if (s32_min >= 0 == s32_max >= 0) {
~~~~~~~~^~~~
To fix the issue, add proper parentheses for the above '>=' condition
to silence the warning/error.
I tried a few clang compilers like clang16 and clang18 and they do not emit
such warnings with -Wparentheses.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307281133.wi0c4SqG-lkp@intel.com/
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230728055740.2284534-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add asm support for new instructions so kernel verifier and bpftool
xlated insn dumps can have proper asm syntax for new instructions.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add interpreter/jit/verifier support for 32bit offset jmp instruction.
If a conditional jmp instruction needs more than 16bit offset,
it can be simulated with a conditional jmp + a 32bit jmp insn.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011231.3716103-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add interpreter/jit support for new signed div/mod insns.
The new signed div/mod instructions are encoded with
unsigned div/mod instructions plus insn->off == 1.
Also add basic verifier support to ensure new insns get
accepted.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011219.3714605-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The existing 'be' and 'le' insns will do conditional bswap
depends on host endianness. This patch implements
unconditional bswap insns.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011213.3712808-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, if user accesses a ctx member with signed types,
the compiler will generate an unsigned load followed by
necessary left and right shifts.
With the introduction of sign-extension load, compiler may
just emit a ldsx insn instead. Let us do a final movsx sign
extension to the final unsigned ctx load result to
satisfy original sign extension requirement.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011207.3712528-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add interpreter/jit support for new sign-extension mov insns.
The original 'MOV' insn is extended to support reg-to-reg
signed version for both ALU and ALU64 operations. For ALU mode,
the insn->off value of 8 or 16 indicates sign-extension
from 8- or 16-bit value to 32-bit value. For ALU64 mode,
the insn->off value of 8/16/32 indicates sign-extension
from 8-, 16- or 32-bit value to 64-bit value.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011202.3712300-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add interpreter/jit support for new sign-extension load insns
which adds a new mode (BPF_MEMSX).
Also add verifier support to recognize these insns and to
do proper verification with new insns. In verifier, besides
to deduce proper bounds for the dst_reg, probed memory access
is also properly handled.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011156.3711870-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Splitting these out into separate helper functions means that we
actually pass an uninitialized variable into another function call
if dec_active() happens to not be inlined, and CONFIG_PREEMPT_RT
is disabled:
kernel/bpf/memalloc.c: In function 'add_obj_to_free_list':
kernel/bpf/memalloc.c:200:9: error: 'flags' is used uninitialized [-Werror=uninitialized]
200 | dec_active(c, flags);
Avoid this by passing the flags by reference, so they either get
initialized and dereferenced through a pointer, or the pointer never
gets accessed at all.
Fixes: 18e027b1c7 ("bpf: Factor out inc/dec of active flag into helpers.")
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230725202653.2905259-1-arnd@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In later patches, we're going to change how the inode's ctime field is
used. Switch to using accessor functions instead of raw accesses of
inode->i_ctime.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230705190309.579783-84-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This work refactors and adds a lightweight extension ("tcx") to the tc BPF
ingress and egress data path side for allowing BPF program management based
on fds via bpf() syscall through the newly added generic multi-prog API.
The main goal behind this work which we also presented at LPC [0] last year
and a recent update at LSF/MM/BPF this year [3] is to support long-awaited
BPF link functionality for tc BPF programs, which allows for a model of safe
ownership and program detachment.
Given the rise in tc BPF users in cloud native environments, this becomes
necessary to avoid hard to debug incidents either through stale leftover
programs or 3rd party applications accidentally stepping on each others toes.
As a recap, a BPF link represents the attachment of a BPF program to a BPF
hook point. The BPF link holds a single reference to keep BPF program alive.
Moreover, hook points do not reference a BPF link, only the application's
fd or pinning does. A BPF link holds meta-data specific to attachment and
implements operations for link creation, (atomic) BPF program update,
detachment and introspection. The motivation for BPF links for tc BPF programs
is multi-fold, for example:
- From Meta: "It's especially important for applications that are deployed
fleet-wide and that don't "control" hosts they are deployed to. If such
application crashes and no one notices and does anything about that, BPF
program will keep running draining resources or even just, say, dropping
packets. We at FB had outages due to such permanent BPF attachment
semantics. With fd-based BPF link we are getting a framework, which allows
safe, auto-detachable behavior by default, unless application explicitly
opts in by pinning the BPF link." [1]
- From Cilium-side the tc BPF programs we attach to host-facing veth devices
and phys devices build the core datapath for Kubernetes Pods, and they
implement forwarding, load-balancing, policy, EDT-management, etc, within
BPF. Currently there is no concept of 'safe' ownership, e.g. we've recently
experienced hard-to-debug issues in a user's staging environment where
another Kubernetes application using tc BPF attached to the same prio/handle
of cls_bpf, accidentally wiping all Cilium-based BPF programs from underneath
it. The goal is to establish a clear/safe ownership model via links which
cannot accidentally be overridden. [0,2]
BPF links for tc can co-exist with non-link attachments, and the semantics are
in line also with XDP links: BPF links cannot replace other BPF links, BPF
links cannot replace non-BPF links, non-BPF links cannot replace BPF links and
lastly only non-BPF links can replace non-BPF links. In case of Cilium, this
would solve mentioned issue of safe ownership model as 3rd party applications
would not be able to accidentally wipe Cilium programs, even if they are not
BPF link aware.
Earlier attempts [4] have tried to integrate BPF links into core tc machinery
to solve cls_bpf, which has been intrusive to the generic tc kernel API with
extensions only specific to cls_bpf and suboptimal/complex since cls_bpf could
be wiped from the qdisc also. Locking a tc BPF program in place this way, is
getting into layering hacks given the two object models are vastly different.
We instead implemented the tcx (tc 'express') layer which is an fd-based tc BPF
attach API, so that the BPF link implementation blends in naturally similar to
other link types which are fd-based and without the need for changing core tc
internal APIs. BPF programs for tc can then be successively migrated from classic
cls_bpf to the new tc BPF link without needing to change the program's source
code, just the BPF loader mechanics for attaching is sufficient.
For the current tc framework, there is no change in behavior with this change
and neither does this change touch on tc core kernel APIs. The gist of this
patch is that the ingress and egress hook have a lightweight, qdisc-less
extension for BPF to attach its tc BPF programs, in other words, a minimal
entry point for tc BPF. The name tcx has been suggested from discussion of
earlier revisions of this work as a good fit, and to more easily differ between
the classic cls_bpf attachment and the fd-based one.
For the ingress and egress tcx points, the device holds a cache-friendly array
with program pointers which is separated from control plane (slow-path) data.
Earlier versions of this work used priority to determine ordering and expression
of dependencies similar as with classic tc, but it was challenged that for
something more future-proof a better user experience is required. Hence this
resulted in the design and development of the generic attach/detach/query API
for multi-progs. See prior patch with its discussion on the API design. tcx is
the first user and later we plan to integrate also others, for example, one
candidate is multi-prog support for XDP which would benefit and have the same
'look and feel' from API perspective.
The goal with tcx is to have maximum compatibility to existing tc BPF programs,
so they don't need to be rewritten specifically. Compatibility to call into
classic tcf_classify() is also provided in order to allow successive migration
or both to cleanly co-exist where needed given its all one logical tc layer and
the tcx plus classic tc cls/act build one logical overall processing pipeline.
tcx supports the simplified return codes TCX_NEXT which is non-terminating (go
to next program) and terminating ones with TCX_PASS, TCX_DROP, TCX_REDIRECT.
The fd-based API is behind a static key, so that when unused the code is also
not entered. The struct tcx_entry's program array is currently static, but
could be made dynamic if necessary at a point in future. The a/b pair swap
design has been chosen so that for detachment there are no allocations which
otherwise could fail.
The work has been tested with tc-testing selftest suite which all passes, as
well as the tc BPF tests from the BPF CI, and also with Cilium's L4LB.
Thanks also to Nikolay Aleksandrov and Martin Lau for in-depth early reviews
of this work.
[0] https://lpc.events/event/16/contributions/1353/
[1] https://lore.kernel.org/bpf/CAEf4BzbokCJN33Nw_kg82sO=xppXnKWEncGTWCTB9vGCmLB6pw@mail.gmail.com
[2] https://colocatedeventseu2023.sched.com/event/1Jo6O/tales-from-an-ebpf-programs-murder-mystery-hemanth-malla-guillaume-fournier-datadog
[3] http://vger.kernel.org/bpfconf2023_material/tcx_meta_netdev_borkmann.pdf
[4] https://lore.kernel.org/bpf/20210604063116.234316-1-memxor@gmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230719140858.13224-3-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This adds a generic layer called bpf_mprog which can be reused by different
attachment layers to enable multi-program attachment and dependency resolution.
In-kernel users of the bpf_mprog don't need to care about the dependency
resolution internals, they can just consume it with few API calls.
The initial idea of having a generic API sparked out of discussion [0] from an
earlier revision of this work where tc's priority was reused and exposed via
BPF uapi as a way to coordinate dependencies among tc BPF programs, similar
as-is for classic tc BPF. The feedback was that priority provides a bad user
experience and is hard to use [1], e.g.:
I cannot help but feel that priority logic copy-paste from old tc, netfilter
and friends is done because "that's how things were done in the past". [...]
Priority gets exposed everywhere in uapi all the way to bpftool when it's
right there for users to understand. And that's the main problem with it.
The user don't want to and don't need to be aware of it, but uapi forces them
to pick the priority. [...] Your cover letter [0] example proves that in
real life different service pick the same priority. They simply don't know
any better. Priority is an unnecessary magic that apps _have_ to pick, so
they just copy-paste and everyone ends up using the same.
The course of the discussion showed more and more the need for a generic,
reusable API where the "same look and feel" can be applied for various other
program types beyond just tc BPF, for example XDP today does not have multi-
program support in kernel, but also there was interest around this API for
improving management of cgroup program types. Such common multi-program
management concept is useful for BPF management daemons or user space BPF
applications coordinating internally about their attachments.
Both from Cilium and Meta side [2], we've collected the following requirements
for a generic attach/detach/query API for multi-progs which has been implemented
as part of this work:
- Support prog-based attach/detach and link API
- Dependency directives (can also be combined):
- BPF_F_{BEFORE,AFTER} with relative_{fd,id} which can be {prog,link,none}
- BPF_F_ID flag as {fd,id} toggle; the rationale for id is so that user
space application does not need CAP_SYS_ADMIN to retrieve foreign fds
via bpf_*_get_fd_by_id()
- BPF_F_LINK flag as {prog,link} toggle
- If relative_{fd,id} is none, then BPF_F_BEFORE will just prepend, and
BPF_F_AFTER will just append for attaching
- Enforced only at attach time
- BPF_F_REPLACE with replace_bpf_fd which can be prog, links have their
own infra for replacing their internal prog
- If no flags are set, then it's default append behavior for attaching
- Internal revision counter and optionally being able to pass expected_revision
- User space application can query current state with revision, and pass it
along for attachment to assert current state before doing updates
- Query also gets extension for link_ids array and link_attach_flags:
- prog_ids are always filled with program IDs
- link_ids are filled with link IDs when link was used, otherwise 0
- {prog,link}_attach_flags for holding {prog,link}-specific flags
- Must be easy to integrate/reuse for in-kernel users
The uapi-side changes needed for supporting bpf_mprog are rather minimal,
consisting of the additions of the attachment flags, revision counter, and
expanding existing union with relative_{fd,id} member.
The bpf_mprog framework consists of an bpf_mprog_entry object which holds
an array of bpf_mprog_fp (fast-path structure). The bpf_mprog_cp (control-path
structure) is part of bpf_mprog_bundle. Both have been separated, so that
fast-path gets efficient packing of bpf_prog pointers for maximum cache
efficiency. Also, array has been chosen instead of linked list or other
structures to remove unnecessary indirections for a fast point-to-entry in
tc for BPF.
The bpf_mprog_entry comes as a pair via bpf_mprog_bundle so that in case of
updates the peer bpf_mprog_entry is populated and then just swapped which
avoids additional allocations that could otherwise fail, for example, in
detach case. bpf_mprog_{fp,cp} arrays are currently static, but they could
be converted to dynamic allocation if necessary at a point in future.
Locking is deferred to the in-kernel user of bpf_mprog, for example, in case
of tcx which uses this API in the next patch, it piggybacks on rtnl.
An extensive test suite for checking all aspects of this API for prog-based
attach/detach and link API comes as BPF selftests in this series.
Thanks also to Andrii Nakryiko for early API discussions wrt Meta's BPF prog
management.
[0] https://lore.kernel.org/bpf/20221004231143.19190-1-daniel@iogearbox.net
[1] https://lore.kernel.org/bpf/CAADnVQ+gEY3FjCR=+DmjDR4gp5bOYZUFJQXj4agKFHT9CQPZBw@mail.gmail.com
[2] http://vger.kernel.org/bpfconf2023_material/tcx_meta_netdev_borkmann.pdf
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20230719140858.13224-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Register the bpf_map_sum_elem_count func for all programs, and update the
map_ptr subtest of the test_progs test to test the new functionality.
The usage is allowed as long as the pointer to the map is trusted (when
using tracing programs) or is a const pointer to map, as in the following
example:
struct {
__uint(type, BPF_MAP_TYPE_HASH);
...
} hash SEC(".maps");
...
static inline int some_bpf_prog(void)
{
struct bpf_map *map = (struct bpf_map *)&hash;
__s64 count;
count = bpf_map_sum_elem_count(map);
...
}
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230719092952.41202-5-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We use the map pointer only to read the counter values, no locking
involved, so mark the argument as const.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230719092952.41202-4-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add the BTF id of struct bpf_map to the reg2btf_ids array. This makes the
values of the CONST_PTR_TO_MAP type to be considered as trusted by kfuncs.
This, in turn, allows users to execute trusted kfuncs which accept `struct
bpf_map *` arguments from non-tracing programs.
While exporting the btf_bpf_map_id variable, save some bytes by defining
it as BTF_ID_LIST_GLOBAL_SINGLE (which is u32[1]) and not as BTF_ID_LIST
(which is u32[64]).
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230719092952.41202-3-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The reg2btf_ids array contains a list of types for which we can (and need)
to find a corresponding static BTF id. All the types in the list can be
considered as trusted for purposes of kfuncs.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230719092952.41202-2-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
As described by Kumar in [0], in shared ownership scenarios it is
necessary to do runtime tracking of {rb,list} node ownership - and
synchronize updates using this ownership information - in order to
prevent races. This patch adds an 'owner' field to struct bpf_list_node
and bpf_rb_node to implement such runtime tracking.
The owner field is a void * that describes the ownership state of a
node. It can have the following values:
NULL - the node is not owned by any data structure
BPF_PTR_POISON - the node is in the process of being added to a data
structure
ptr_to_root - the pointee is a data structure 'root'
(bpf_rb_root / bpf_list_head) which owns this node
The field is initially NULL (set by bpf_obj_init_field default behavior)
and transitions states in the following sequence:
Insertion: NULL -> BPF_PTR_POISON -> ptr_to_root
Removal: ptr_to_root -> NULL
Before a node has been successfully inserted, it is not protected by any
root's lock, and therefore two programs can attempt to add the same node
to different roots simultaneously. For this reason the intermediate
BPF_PTR_POISON state is necessary. For removal, the node is protected
by some root's lock so this intermediate hop isn't necessary.
Note that bpf_list_pop_{front,back} helpers don't need to check owner
before removing as the node-to-be-removed is not passed in as input and
is instead taken directly from the list. Do the check anyways and
WARN_ON_ONCE in this unexpected scenario.
Selftest changes in this patch are entirely mechanical: some BTF
tests have hardcoded struct sizes for structs that contain
bpf_{list,rb}_node fields, those were adjusted to account for the new
sizes. Selftest additions to validate the owner field are added in a
further patch in the series.
[0]: https://lore.kernel.org/bpf/d7hyspcow5wtjcmw4fugdgyp3fwhljwuscp3xyut5qnwivyeru@ysdq543otzv2
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Suggested-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230718083813.3416104-4-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Structs bpf_rb_node and bpf_list_node are opaquely defined in
uapi/linux/bpf.h, as BPF program writers are not expected to touch their
fields - nor does the verifier allow them to do so.
Currently these structs are simple wrappers around structs rb_node and
list_head and linked_list / rbtree implementation just casts and passes
to library functions for those data structures. Later patches in this
series, though, will add an "owner" field to bpf_{rb,list}_node, such
that they're not just wrapping an underlying node type. Moreover, the
bpf linked_list and rbtree implementations will deal with these owner
pointers directly in a few different places.
To avoid having to do
void *owner = (void*)bpf_list_node + sizeof(struct list_head)
with opaque UAPI node types, add bpf_{list,rb}_node_kern struct
definitions to internal headers and modify linked_list and rbtree to use
the internal types where appropriate.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230718083813.3416104-3-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
While the check_max_stack_depth function explores call chains emanating
from the main prog, which is typically enough to cover all possible call
chains, it doesn't explore those rooted at async callbacks unless the
async callback will have been directly called, since unlike non-async
callbacks it skips their instruction exploration as they don't
contribute to stack depth.
It could be the case that the async callback leads to a callchain which
exceeds the stack depth, but this is never reachable while only
exploring the entry point from main subprog. Hence, repeat the check for
the main subprog *and* all async callbacks marked by the symbolic
execution pass of the verifier, as execution of the program may begin at
any of them.
Consider functions with following stack depths:
main: 256
async: 256
foo: 256
main:
rX = async
bpf_timer_set_callback(...)
async:
foo()
Here, async is not descended as it does not contribute to stack depth of
main (since it is referenced using bpf_pseudo_func and not
bpf_pseudo_call). However, when async is invoked asynchronously, it will
end up breaching the MAX_BPF_STACK limit by calling foo.
Hence, in addition to main, we also need to explore call chains
beginning at all async callback subprogs in a program.
Fixes: 7ddc80a476 ("bpf: Teach stack depth check about async callbacks.")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230717161530.1238-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The assignment to idx in check_max_stack_depth happens once we see a
bpf_pseudo_call or bpf_pseudo_func. This is not an issue as the rest of
the code performs a few checks and then pushes the frame to the frame
stack, except the case of async callbacks. If the async callback case
causes the loop iteration to be skipped, the idx assignment will be
incorrect on the next iteration of the loop. The value stored in the
frame stack (as the subprogno of the current subprog) will be incorrect.
This leads to incorrect checks and incorrect tail_call_reachable
marking. Save the target subprog in a new variable and only assign to
idx once we are done with the is_async_cb check which may skip pushing
of frame to the frame stack and subsequent stack depth checks and tail
call markings.
Fixes: 7ddc80a476 ("bpf: Teach stack depth check about async callbacks.")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230717161530.1238-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Alexei Starovoitov says:
====================
pull-request: bpf-next 2023-07-13
We've added 67 non-merge commits during the last 15 day(s) which contain
a total of 106 files changed, 4444 insertions(+), 619 deletions(-).
The main changes are:
1) Fix bpftool build in presence of stale vmlinux.h,
from Alexander Lobakin.
2) Introduce bpf_me_mcache_free_rcu() and fix OOM under stress,
from Alexei Starovoitov.
3) Teach verifier actual bounds of bpf_get_smp_processor_id()
and fix perf+libbpf issue related to custom section handling,
from Andrii Nakryiko.
4) Introduce bpf map element count, from Anton Protopopov.
5) Check skb ownership against full socket, from Kui-Feng Lee.
6) Support for up to 12 arguments in BPF trampoline, from Menglong Dong.
7) Export rcu_request_urgent_qs_task, from Paul E. McKenney.
8) Fix BTF walking of unions, from Yafang Shao.
9) Extend link_info for kprobe_multi and perf_event links,
from Yafang Shao.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (67 commits)
selftests/bpf: Add selftest for PTR_UNTRUSTED
bpf: Fix an error in verifying a field in a union
selftests/bpf: Add selftests for nested_trust
bpf: Fix an error around PTR_UNTRUSTED
selftests/bpf: add testcase for TRACING with 6+ arguments
bpf, x86: allow function arguments up to 12 for TRACING
bpf, x86: save/restore regs with BPF_DW size
bpftool: Use "fallthrough;" keyword instead of comments
bpf: Add object leak check.
bpf: Convert bpf_cpumask to bpf_mem_cache_free_rcu.
bpf: Introduce bpf_mem_free_rcu() similar to kfree_rcu().
selftests/bpf: Improve test coverage of bpf_mem_alloc.
rcu: Export rcu_request_urgent_qs_task()
bpf: Allow reuse from waiting_for_gp_ttrace list.
bpf: Add a hint to allocated objects.
bpf: Change bpf_mem_cache draining process.
bpf: Further refactor alloc_bulk().
bpf: Factor out inc/dec of active flag into helpers.
bpf: Refactor alloc_bulk().
bpf: Let free_all() return the number of freed elements.
...
====================
Link: https://lore.kernel.org/r/20230714020910.80794-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We are utilizing BPF LSM to monitor BPF operations within our container
environment. When we add support for raw_tracepoint, it hits below
error.
; (const void *)attr->raw_tracepoint.name);
27: (79) r3 = *(u64 *)(r2 +0)
access beyond the end of member map_type (mend:4) in struct (anon) with off 0 size 8
It can be reproduced with below BPF prog.
SEC("lsm/bpf")
int BPF_PROG(bpf_audit, int cmd, union bpf_attr *attr, unsigned int size)
{
switch (cmd) {
case BPF_RAW_TRACEPOINT_OPEN:
bpf_printk("raw_tracepoint is %s", attr->raw_tracepoint.name);
break;
default:
break;
}
return 0;
}
The reason is that when accessing a field in a union, such as bpf_attr,
if the field is located within a nested struct that is not the first
member of the union, it can result in incorrect field verification.
union bpf_attr {
struct {
__u32 map_type; <<<< Actually it will find that field.
__u32 key_size;
__u32 value_size;
...
};
...
struct {
__u64 name; <<<< We want to verify this field.
__u32 prog_fd;
} raw_tracepoint;
};
Considering the potential deep nesting levels, finding a perfect
solution to address this issue has proven challenging. Therefore, I
propose a solution where we simply skip the verification process if the
field in question is located within a union.
Fixes: 7e3617a72d ("bpf: Add array support to btf_struct_access")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230713025642.27477-4-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Per discussion with Alexei, the PTR_UNTRUSTED flag should not been
cleared when we start to walk a new struct, because the struct in
question may be a struct nested in a union. We should also check and set
this flag before we walk its each member, in case itself is a union.
We will clear this flag if the field is BTF_TYPE_SAFE_RCU_OR_NULL.
Fixes: 6fcd486b3a ("bpf: Refactor RCU enforcement in the verifier.")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230713025642.27477-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The object leak check is cheap. Do it unconditionally to spot difficult races
in bpf_mem_alloc.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230706033447.54696-15-alexei.starovoitov@gmail.com
Convert bpf_cpumask to bpf_mem_cache_free_rcu.
Note that migrate_disable() in bpf_cpumask_release() is still necessary, since
bpf_cpumask_release() is a dtor. bpf_obj_free_fields() can be converted to do
migrate_disable() there in a follow up.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230706033447.54696-14-alexei.starovoitov@gmail.com
Introduce bpf_mem_[cache_]free_rcu() similar to kfree_rcu().
Unlike bpf_mem_[cache_]free() that links objects for immediate reuse into
per-cpu free list the _rcu() flavor waits for RCU grace period and then moves
objects into free_by_rcu_ttrace list where they are waiting for RCU
task trace grace period to be freed into slab.
The life cycle of objects:
alloc: dequeue free_llist
free: enqeueu free_llist
free_rcu: enqueue free_by_rcu -> waiting_for_gp
free_llist above high watermark -> free_by_rcu_ttrace
after RCU GP waiting_for_gp -> free_by_rcu_ttrace
free_by_rcu_ttrace -> waiting_for_gp_ttrace -> slab
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20230706033447.54696-13-alexei.starovoitov@gmail.com
alloc_bulk() can reuse elements from free_by_rcu_ttrace.
Let it reuse from waiting_for_gp_ttrace as well to avoid unnecessary kmalloc().
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230706033447.54696-10-alexei.starovoitov@gmail.com
To address OOM issue when one cpu is allocating and another cpu is freeing add
a target bpf_mem_cache hint to allocated objects and when local cpu free_llist
overflows free to that bpf_mem_cache. The hint addresses the OOM while
maintaining the same performance for common case when alloc/free are done on the
same cpu.
Note that do_call_rcu_ttrace() now has to check 'draining' flag in one more case,
since do_call_rcu_ttrace() is called not only for current cpu.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20230706033447.54696-9-alexei.starovoitov@gmail.com
The next patch will introduce cross-cpu llist access and existing
irq_work_sync() + drain_mem_cache() + rcu_barrier_tasks_trace() mechanism will
not be enough, since irq_work_sync() + drain_mem_cache() on cpu A won't
guarantee that llist on cpu A are empty. The free_bulk() on cpu B might add
objects back to llist of cpu A. Add 'bool draining' flag.
The modified sequence looks like:
for_each_cpu:
WRITE_ONCE(c->draining, true); // do_call_rcu_ttrace() won't be doing call_rcu() any more
irq_work_sync(); // wait for irq_work callback (free_bulk) to finish
drain_mem_cache(); // free all objects
rcu_barrier_tasks_trace(); // wait for RCU callbacks to execute
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20230706033447.54696-8-alexei.starovoitov@gmail.com
In certain scenarios alloc_bulk() might be taking free objects mainly from
free_by_rcu_ttrace list. In such case get_memcg() and set_active_memcg() are
redundant, but they show up in perf profile. Split the loop and only set memcg
when allocating from slab. No performance difference in this patch alone, but
it helps in combination with further patches.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20230706033447.54696-7-alexei.starovoitov@gmail.com
Let free_all() helper return the number of freed elements.
It's not used in this patch, but helps in debug/development of bpf_mem_alloc.
For example this diff for __free_rcu():
- free_all(llist_del_all(&c->waiting_for_gp_ttrace), !!c->percpu_size);
+ printk("cpu %d freed %d objs after tasks trace\n", raw_smp_processor_id(),
+ free_all(llist_del_all(&c->waiting_for_gp_ttrace), !!c->percpu_size));
would show how busy RCU tasks trace is.
In artificial benchmark where one cpu is allocating and different cpu is freeing
the RCU tasks trace won't be able to keep up and the list of objects
would keep growing from thousands to millions and eventually OOMing.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20230706033447.54696-4-alexei.starovoitov@gmail.com
bpf_get_smp_processor_id() helper returns current CPU on which BPF
program runs. It can't return value that is bigger than maximum allowed
number of CPUs (minus one, due to zero indexing). Teach BPF verifier to
recognize that. This makes it possible to use bpf_get_smp_processor_id()
result to index into arrays without extra checks, as demonstrated in
subsequent selftests/bpf patch.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230711232400.1658562-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
By introducing support for ->fill_link_info to the perf_event link, users
gain the ability to inspect it using `bpftool link show`. While the current
approach involves accessing this information via `bpftool perf show`,
consolidating link information for all link types in one place offers
greater convenience. Additionally, this patch extends support to the
generic perf event, which is not currently accommodated by
`bpftool perf show`. While only the perf type and config are exposed to
userspace, other attributes such as sample_period and sample_freq are
ignored. It's important to note that if kptr_restrict is not permitted, the
probed address will not be exposed, maintaining security measures.
A new enum bpf_perf_event_type is introduced to help the user understand
which struct is relevant.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-9-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a common helper bpf_copy_to_user(), which will be used at multiple
places.
No functional change.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-8-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add another column to the /sys/fs/bpf/maps.debug iterator to display
cur_entries, the current number of entries in the map as is returned
by the bpf_map_sum_elem_count kfunc. Also fix formatting.
Example:
# cat /sys/fs/bpf/maps.debug
id name max_entries cur_entries
2 iterator.rodata 1 0
125 cilium_auth_map 524288 666
126 cilium_runtime_ 256 0
127 cilium_signals 32 0
128 cilium_node_map 16384 1344
129 cilium_events 32 0
...
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230706133932.45883-5-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Initialize and utilize the per-cpu insertions/deletions counters for hash-based
maps. Non-trivial changes only apply to the preallocated maps for which the
{inc,dec}_elem_count functions are not called, as there's no need in counting
elements to sustain proper map operations.
To increase/decrease percpu counters for preallocated maps we add raw calls to
the bpf_map_{inc,dec}_elem_count functions so that the impact is minimal. For
dynamically allocated maps we add corresponding calls to the existing
{inc,dec}_elem_count functions.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230706133932.45883-4-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A bpf_map_sum_elem_count kfunc was added to simplify getting the sum of the map
per-cpu element counters. If a map doesn't implement the counter, then the
function will always return 0.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230706133932.45883-3-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The check_max_stack_depth pass happens after the verifier's symbolic
execution, and attempts to walk the call graph of the BPF program,
ensuring that the stack usage stays within bounds for all possible call
chains. There are two cases to consider: bpf_pseudo_func and
bpf_pseudo_call. In the former case, the callback pointer is loaded into
a register, and is assumed that it is passed to some helper later which
calls it (however there is no way to be sure), but the check remains
conservative and accounts the stack usage anyway. For this particular
case, asynchronous callbacks are skipped as they execute asynchronously
when their corresponding event fires.
The case of bpf_pseudo_call is simpler and we know that the call is
definitely made, hence the stack depth of the subprog is accounted for.
However, the current check still skips an asynchronous callback even if
a bpf_pseudo_call was made for it. This is erroneous, as it will miss
accounting for the stack usage of the asynchronous callback, which can
be used to breach the maximum stack depth limit.
Fix this by only skipping asynchronous callbacks when the instruction is
not a pseudo call to the subprog.
Fixes: 7ddc80a476 ("bpf: Teach stack depth check about async callbacks.")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230705144730.235802-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The theoretical maximum size of ring buffer is about 64GB, but now the
size of ring buffer is specified by max_entries in bpf_attr and its
maximum value is (4GB - 1), and it won't be possible for overflow.
So just remove the unnecessary size check in ringbuf_map_alloc() but
keep the comments for possible extension in future.
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://lore.kernel.org/bpf/9c636a63-1f3d-442d-9223-96c2dccb9469@moroto.mountain
Link: https://lore.kernel.org/bpf/20230704074014.216616-1-houtao@huaweicloud.com
__register_btf_kfunc_id_set() assumes .BTF to be part of the module's .ko
file if CONFIG_DEBUG_INFO_BTF is enabled. If that's not the case, the
function prints an error message and return an error. As a result, such
modules cannot be loaded.
However, the section could be stripped out during a build process. It would
be better to let the modules loaded, because their basic functionalities
have no problem [0], though the BTF functionalities will not be supported.
Make the function to lower the level of the message from error to warn, and
return no error.
[0] https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion
Fixes: c446fdacb1 ("bpf: fix register_btf_kfunc_id_set for !CONFIG_DEBUG_INFO_BTF")
Reported-by: Alexander Egorenkov <Alexander.Egorenkov@ibm.com>
Suggested-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/87y228q66f.fsf@oc8242746057.ibm.com
Link: https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion
Link: https://lore.kernel.org/bpf/20230701171447.56464-1-sj@kernel.org
It is impossible to use skb_frag_t in the tracing program. Resolve typedefs
when walking structs.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20230626212522.2414485-1-sdf@google.com
The -target option has been deprecated since clang 3.4 in 2013. Therefore, use
the preferred --target=bpf form instead. This also matches how we use --target=
in scripts/Makefile.clang.
Signed-off-by: Fangrui Song <maskray@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: 274b6f0c87
Link: https://lore.kernel.org/bpf/20230624001856.1903733-1-maskray@google.com
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2023-06-23
We've added 49 non-merge commits during the last 24 day(s) which contain
a total of 70 files changed, 1935 insertions(+), 442 deletions(-).
The main changes are:
1) Extend bpf_fib_lookup helper to allow passing the route table ID,
from Louis DeLosSantos.
2) Fix regsafe() in verifier to call check_ids() for scalar registers,
from Eduard Zingerman.
3) Extend the set of cpumask kfuncs with bpf_cpumask_first_and()
and a rework of bpf_cpumask_any*() kfuncs. Additionally,
add selftests, from David Vernet.
4) Fix socket lookup BPF helpers for tc/XDP to respect VRF bindings,
from Gilad Sever.
5) Change bpf_link_put() to use workqueue unconditionally to fix it
under PREEMPT_RT, from Sebastian Andrzej Siewior.
6) Follow-ups to address issues in the bpf_refcount shared ownership
implementation, from Dave Marchevsky.
7) A few general refactorings to BPF map and program creation permissions
checks which were part of the BPF token series, from Andrii Nakryiko.
8) Various fixes for benchmark framework and add a new benchmark
for BPF memory allocator to BPF selftests, from Hou Tao.
9) Documentation improvements around iterators and trusted pointers,
from Anton Protopopov.
10) Small cleanup in verifier to improve allocated object check,
from Daniel T. Lee.
11) Improve performance of bpf_xdp_pointer() by avoiding access
to shared_info when XDP packet does not have frags,
from Jesper Dangaard Brouer.
12) Silence a harmless syzbot-reported warning in btf_type_id_size(),
from Yonghong Song.
13) Remove duplicate bpfilter_umh_cleanup in favor of umd_cleanup_helper,
from Jarkko Sakkinen.
14) Fix BPF selftests build for resolve_btfids under custom HOSTCFLAGS,
from Viktor Malik.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (49 commits)
bpf, docs: Document existing macros instead of deprecated
bpf, docs: BPF Iterator Document
selftests/bpf: Fix compilation failure for prog vrf_socket_lookup
selftests/bpf: Add vrf_socket_lookup tests
bpf: Fix bpf socket lookup from tc/xdp to respect socket VRF bindings
bpf: Call __bpf_sk_lookup()/__bpf_skc_lookup() directly via TC hookpoint
bpf: Factor out socket lookup functions for the TC hookpoint.
selftests/bpf: Set the default value of consumer_cnt as 0
selftests/bpf: Ensure that next_cpu() returns a valid CPU number
selftests/bpf: Output the correct error code for pthread APIs
selftests/bpf: Use producer_cnt to allocate local counter array
xsk: Remove unused inline function xsk_buff_discard()
bpf: Keep BPF_PROG_LOAD permission checks clear of validations
bpf: Centralize permissions checks for all BPF map types
bpf: Inline map creation logic in map_create() function
bpf: Move unprivileged checks into map_create() and bpf_prog_load()
bpf: Remove in_atomic() from bpf_link_put().
selftests/bpf: Verify that check_ids() is used for scalars in regsafe()
bpf: Verify scalar ids mapping in regsafe() using check_ids()
selftests/bpf: Check if mark_chain_precision() follows scalar ids
...
====================
Link: https://lore.kernel.org/r/20230623211256.8409-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We currently allow to create perf link for program with
expected_attach_type == BPF_TRACE_KPROBE_MULTI.
This will cause crash when we call helpers like get_attach_cookie or
get_func_ip in such program, because it will call the kprobe_multi's
version (current->bpf_ctx context setup) of those helpers while it
expects perf_link's current->bpf_ctx context setup.
Making sure that we use BPF_TRACE_KPROBE_MULTI expected_attach_type
only for programs attaching through kprobe_multi link.
Fixes: ca74823c6e ("bpf: Add cookie support to programs attached with kprobe multi link")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230618131414.75649-1-jolsa@kernel.org
When building a kernel with LLVM=1, LLVM_IAS=0 and CONFIG_KASAN=y, LLVM
leaves DWARF tags for the "asan.module_ctor" & co symbols. In turn,
pahole creates BTF_KIND_FUNC entries for these and this makes the BTF
metadata validation fail because they contain a dot.
In a dramatic turn of event, this BTF verification failure can cause
the netfilter_bpf initialization to fail, causing netfilter_core to
free the netfilter_helper hashmap and netfilter_ftp to trigger a
use-after-free. The risk of u-a-f in netfilter will be addressed
separately but the existence of "asan.module_ctor" debug info under some
build conditions sounds like a good enough reason to accept functions
that contain dots in BTF.
Although using only LLVM=1 is the recommended way to compile clang-based
kernels, users can certainly do LLVM=1, LLVM_IAS=0 as well and we still
try to support that combination according to Nick. To clarify:
- > v5.10 kernel, LLVM=1 (LLVM_IAS=0 is not the default) is recommended,
but user can still have LLVM=1, LLVM_IAS=0 to trigger the issue
- <= 5.10 kernel, LLVM=1 (LLVM_IAS=0 is the default) is recommended in
which case GNU as will be used
Fixes: 1dc9285184 ("bpf: kernel side support for BTF Var and DataSec")
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Yonghong Song <yhs@meta.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/bpf/20230615145607.3469985-1-revest@chromium.org
Move out flags validation and license checks out of the permission
checks. They were intermingled, which makes subsequent changes harder.
Clean this up: perform straightforward flag validation upfront, and
fetch and check license later, right where we use it. Also consolidate
capabilities check in one block, right after basic attribute sanity
checks.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230613223533.3689589-5-andrii@kernel.org
This allows to do more centralized decisions later on, and generally
makes it very explicit which maps are privileged and which are not
(e.g., LRU_HASH and LRU_PERCPU_HASH, which are privileged HASH variants,
as opposed to unprivileged HASH and HASH_PERCPU; now this is explicit
and easy to verify).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230613223533.3689589-4-andrii@kernel.org
Currently find_and_alloc_map() performs two separate functions: some
argument sanity checking and partial map creation workflow hanling.
Neither of those functions are self-sufficient and are augmented by
further checks and initialization logic in the caller (map_create()
function). So unify all the sanity checks, permission checks, and
creation and initialization logic in one linear piece of code in
map_create() instead. This also make it easier to further enhance
permission checks and keep them located in one place.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230613223533.3689589-3-andrii@kernel.org
Make each bpf() syscall command a bit more self-contained, making it
easier to further enhance it. We move sysctl_unprivileged_bpf_disabled
handling down to map_create() and bpf_prog_load(), two special commands
in this regard.
Also swap the order of checks, calling bpf_capable() only if
sysctl_unprivileged_bpf_disabled is true, avoiding unnecessary audit
messages.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230613223533.3689589-2-andrii@kernel.org
bpf_free_inode() is invoked as a RCU callback. Usually RCU callbacks are
invoked within softirq context. By setting rcutree.use_softirq=0 boot
option the RCU callbacks will be invoked in a per-CPU kthread with
bottom halves disabled which implies a RCU read section.
On PREEMPT_RT the context remains fully preemptible. The RCU read
section however does not allow schedule() invocation. The latter happens
in mutex_lock() performed by bpf_trampoline_unlink_prog() originated
from bpf_link_put().
It was pointed out that the bpf_link_put() invocation should not be
delayed if originated from close(). It was also pointed out that other
invocations from within a syscall should also avoid the workqueue.
Everyone else should use workqueue by default to remain safe in the
future (while auditing the code, every caller was preemptible except for
the RCU case).
Let bpf_link_put() use the worker unconditionally. Add
bpf_link_put_direct() which will directly free the resources and is used
by close() and from within __sys_bpf().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230614083430.oENawF8f@linutronix.de
Make sure that the following unsafe example is rejected by verifier:
1: r9 = ... some pointer with range X ...
2: r6 = ... unbound scalar ID=a ...
3: r7 = ... unbound scalar ID=b ...
4: if (r6 > r7) goto +1
5: r6 = r7
6: if (r6 > X) goto ...
--- checkpoint ---
7: r9 += r7
8: *(u64 *)r9 = Y
This example is unsafe because not all execution paths verify r7 range.
Because of the jump at (4) the verifier would arrive at (6) in two states:
I. r6{.id=b}, r7{.id=b} via path 1-6;
II. r6{.id=a}, r7{.id=b} via path 1-4, 6.
Currently regsafe() does not call check_ids() for scalar registers,
thus from POV of regsafe() states (I) and (II) are identical. If the
path 1-6 is taken by verifier first, and checkpoint is created at (6)
the path [1-4, 6] would be considered safe.
Changes in this commit:
- check_ids() is modified to disallow mapping multiple old_id to the
same cur_id.
- check_scalar_ids() is added, unlike check_ids() it treats ID zero as
a unique scalar ID.
- check_scalar_ids() needs to generate temporary unique IDs, field
'tmp_id_gen' is added to bpf_verifier_env::idmap_scratch to
facilitate this.
- regsafe() is updated to:
- use check_scalar_ids() for precise scalar registers.
- compare scalar registers using memcmp only for explore_alu_limits
branch. This simplifies control flow for scalar case, and has no
measurable performance impact.
- check_alu_op() is updated to avoid generating bpf_reg_state::id for
constant scalar values when processing BPF_MOV. ID is needed to
propagate range information for identical values, but there is
nothing to propagate for constants.
Fixes: 75748837b7 ("bpf: Propagate scalar ranges through register assignments.")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230613153824.3324830-4-eddyz87@gmail.com
Change mark_chain_precision() to track precision in situations
like below:
r2 = unknown value
...
--- state #0 ---
...
r1 = r2 // r1 and r2 now share the same ID
...
--- state #1 {r1.id = A, r2.id = A} ---
...
if (r2 > 10) goto exit; // find_equal_scalars() assigns range to r1
...
--- state #2 {r1.id = A, r2.id = A} ---
r3 = r10
r3 += r1 // need to mark both r1 and r2
At the beginning of the processing of each state, ensure that if a
register with a scalar ID is marked as precise, all registers sharing
this ID are also marked as precise.
This property would be used by a follow-up change in regsafe().
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230613153824.3324830-2-eddyz87@gmail.com
When subprograms are in use, the main program is not jit'd after the
subprograms because jit_subprogs sets a value for prog->bpf_func upon
success. Subsequent calls to the JIT are bypassed when this value is
non-NULL. This leads to a situation where the main program and its
func[0] counterpart are both in the bpf kallsyms tree, but only func[0]
has an extable. Extables are only created during JIT. Now there are
two nearly identical program ksym entries in the tree, but only one has
an extable. Depending upon how the entries are placed, there's a chance
that a fault will call search_extable on the aux with the NULL entry.
Since jit_subprogs already copies state from func[0] to the main
program, include the extable pointer in this state duplication.
Additionally, ensure that the copy of the main program in func[0] is not
added to the bpf_prog_kallsyms table. Instead, let the main program get
added later in bpf_prog_load(). This ensures there is only a single
copy of the main program in the kallsyms table, and that its tag matches
the tag observed by tooling like bpftool.
Cc: stable@vger.kernel.org
Fixes: 1c2a088a66 ("bpf: x64: add JIT support for multi-function programs")
Signed-off-by: Krister Johansen <kjlx@templeofstupid.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/6de9b2f4b4724ef56efbb0339daaa66c8b68b1e7.1686616663.git.kjlx@templeofstupid.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We currently export the bpf_cpumask_any() and bpf_cpumask_any_and()
kfuncs. Intuitively, one would expect these to choose any CPU in the
cpumask, but what they actually do is alias to cpumask_first() and
cpmkas_first_and().
This is useless given that we already export bpf_cpumask_first() and
bpf_cpumask_first_and(), so this patch replaces them with kfuncs that
call cpumask_any_distribute() and cpumask_any_and_distribute(), which
actually choose any CPU from the cpumask (or the AND of two cpumasks for
the latter).
Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230610035053.117605-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We currently provide bpf_cpumask_first(), bpf_cpumask_any(), and
bpf_cpumask_any_and() kfuncs. bpf_cpumask_any() and
bpf_cpumask_any_and() are confusing misnomers in that they actually just
call cpumask_first() and cpumask_first_and() respectively.
We'll replace them with bpf_cpumask_any_distribute() and
bpf_cpumask_any_distribute_and() kfuncs in a subsequent patch, so let's
ensure feature parity by adding a bpf_cpumask_first_and() kfunc to
account for bpf_cpumask_any_and() being removed.
Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230610035053.117605-1-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This function is only used when CONFIG_BPF_JIT_ALWAYS_ON is disabled, but
CONFIG_BPF_SYSCALL is enabled. When both are turned off, the prototype is
missing but the unused function is still compiled, as seen from this W=1
warning:
[...]
kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]
[...]
Add a matching #ifdef for the definition to leave it out.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20230602135128.1498362-1-arnd@kernel.org
Cross-merge networking fixes after downstream PR.
Conflicts:
net/sched/sch_taprio.c
d636fc5dd6 ("net: sched: add rcu annotations around qdisc->qdisc_sleeping")
dced11ef84 ("net/sched: taprio: don't overwrite "sch" variable in taprio_dump_class_stats()")
net/ipv4/sysctl_net_ipv4.c
e209fee411 ("net/ipv4: ping_group_range: allow GID from 2147483648 to 4294967294")
ccce324dab ("tcp: make the first N SYN RTO backoffs linear")
https://lore.kernel.org/all/20230605100816.08d41a7b@canb.auug.org.au/
No adjacent changes.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The following scenario describes a bug in the verifier where it
incorrectly concludes about equivalent scalar IDs which could lead to
verifier bypass in privileged mode:
1. Prepare a 32-bit rogue number.
2. Put the rogue number into the upper half of a 64-bit register, and
roll a random (unknown to the verifier) bit in the lower half. The
rest of the bits should be zero (although variations are possible).
3. Assign an ID to the register by MOVing it to another arbitrary
register.
4. Perform a 32-bit spill of the register, then perform a 32-bit fill to
another register. Due to a bug in the verifier, the ID will be
preserved, although the new register will contain only the lower 32
bits, i.e. all zeros except one random bit.
At this point there are two registers with different values but the same
ID, which means the integrity of the verifier state has been corrupted.
5. Compare the new 32-bit register with 0. In the branch where it's
equal to 0, the verifier will believe that the original 64-bit
register is also 0, because it has the same ID, but its actual value
still contains the rogue number in the upper half.
Some optimizations of the verifier prevent the actual bypass, so
extra care is needed: the comparison must be between two registers,
and both branches must be reachable (this is why one random bit is
needed). Both branches are still suitable for the bypass.
6. Right shift the original register by 32 bits to pop the rogue number.
7. Use the rogue number as an offset with any pointer. The verifier will
believe that the offset is 0, while in reality it's the given number.
The fix is similar to the 32-bit BPF_MOV handling in check_alu_op for
SCALAR_VALUE. If the spill is narrowing the actual register value, don't
keep the ID, make sure it's reset to 0.
Fixes: 354e8f1970 ("bpf: Support <8-byte scalar spill and refill")
Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Andrii Nakryiko <andrii@kernel.org> # Checked veristat delta
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20230607123951.558971-2-maxtram95@gmail.com
Andrii Nakryiko writes:
And we currently don't have an attach type for NETLINK BPF link.
Thankfully it's not too late to add it. I see that link_create() in
kernel/bpf/syscall.c just bypasses attach_type check. We shouldn't
have done that. Instead we need to add BPF_NETLINK attach type to enum
bpf_attach_type. And wire all that properly throughout the kernel and
libbpf itself.
This adds BPF_NETFILTER and uses it. This breaks uabi but this
wasn't in any non-rc release yet, so it should be fine.
v2: check link_attack prog type in link_create too
Fixes: 84601d6ee6 ("bpf: add bpf_link support for BPF_NETFILTER programs")
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/CAEf4BzZ69YgrQW7DHCJUT_X+GqMq_ZQQPBwopaJJVGFD5=d5Vg@mail.gmail.com/
Link: https://lore.kernel.org/bpf/20230605131445.32016-1-fw@strlen.de
In reg_type_not_null(), we currently assume that a pointer may be NULL
if it has the PTR_MAYBE_NULL modifier, or if it doesn't belong to one of
several base type of pointers that are never NULL-able. For example,
PTR_TO_CTX, PTR_TO_MAP_VALUE, etc.
It turns out that in some cases, PTR_TO_BTF_ID can never be NULL as
well, though we currently don't specify it. For example, if you had the
following program:
SEC("tc")
long example_refcnt_fail(void *ctx)
{
struct bpf_cpumask *mask1, *mask2;
mask1 = bpf_cpumask_create();
mask2 = bpf_cpumask_create();
if (!mask1 || !mask2)
goto error_release;
bpf_cpumask_test_cpu(0, (const struct cpumask *)mask1);
bpf_cpumask_test_cpu(0, (const struct cpumask *)mask2);
error_release:
if (mask1)
bpf_cpumask_release(mask1);
if (mask2)
bpf_cpumask_release(mask2);
return ret;
}
The verifier will incorrectly fail to load the program, thinking
(unintuitively) that we have a possibly-unreleased reference if the mask
is NULL, because we (correctly) don't issue a bpf_cpumask_release() on
the NULL path.
The reason the verifier gets confused is due to the fact that we don't
explicitly tell the verifier that trusted PTR_TO_BTF_ID pointers can
never be NULL. Basically, if we successfully get past the if check
(meaning both pointers go from ptr_or_null_bpf_cpumask to
ptr_bpf_cpumask), the verifier will correctly assume that the references
need to be dropped on any possible branch that leads to program exit.
However, it will _incorrectly_ think that the ptr == NULL branch is
possible, and will erroneously detect it as a branch on which we failed
to drop the reference.
The solution is of course to teach the verifier that trusted
PTR_TO_BTF_ID pointers can never be NULL, so that it doesn't incorrectly
think it's possible for the reference to be present on the ptr == NULL
branch.
A follow-on patch will add a selftest that verifies this behavior.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230602150112.1494194-1-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
>From commit 282de143ea ("bpf: Introduce allocated objects support"),
With this allocated object with BPF program, (PTR_TO_BTF_ID | MEM_ALLOC)
has been a way of indicating to check the type is the allocated object.
commit d8939cb0a0 ("bpf: Loosen alloc obj test in verifier's
reg_btf_record")
>From the commit, there has been helper function for checking this, named
type_is_ptr_alloc_obj(). But still, some of the code use open code to
retrieve this info. This commit replaces the open code with the
type_is_alloc(), and the type_is_ptr_alloc_obj() function.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230527122706.59315-1-danieltimlee@gmail.com
This patch fixes an incorrect assumption made in the original
bpf_refcount series [0], specifically that the BPF program calling
bpf_refcount_acquire on some node can always guarantee that the node is
alive. In that series, the patch adding failure behavior to rbtree_add
and list_push_{front, back} breaks this assumption for non-owning
references.
Consider the following program:
n = bpf_kptr_xchg(&mapval, NULL);
/* skip error checking */
bpf_spin_lock(&l);
if(bpf_rbtree_add(&t, &n->rb, less)) {
bpf_refcount_acquire(n);
/* Failed to add, do something else with the node */
}
bpf_spin_unlock(&l);
It's incorrect to assume that bpf_refcount_acquire will always succeed in this
scenario. bpf_refcount_acquire is being called in a critical section
here, but the lock being held is associated with rbtree t, which isn't
necessarily the lock associated with the tree that the node is already
in. So after bpf_rbtree_add fails to add the node and calls bpf_obj_drop
in it, the program has no ownership of the node's lifetime. Therefore
the node's refcount can be decr'd to 0 at any time after the failing
rbtree_add. If this happens before the refcount_acquire above, the node
might be free'd, and regardless refcount_acquire will be incrementing a
0 refcount.
Later patches in the series exercise this scenario, resulting in the
expected complaint from the kernel (without this patch's changes):
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 207 at lib/refcount.c:25 refcount_warn_saturate+0xbc/0x110
Modules linked in: bpf_testmod(O)
CPU: 1 PID: 207 Comm: test_progs Tainted: G O 6.3.0-rc7-02231-g723de1a718a2-dirty #371
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
RIP: 0010:refcount_warn_saturate+0xbc/0x110
Code: 6f 64 f6 02 01 e8 84 a3 5c ff 0f 0b eb 9d 80 3d 5e 64 f6 02 00 75 94 48 c7 c7 e0 13 d2 82 c6 05 4e 64 f6 02 01 e8 64 a3 5c ff <0f> 0b e9 7a ff ff ff 80 3d 38 64 f6 02 00 0f 85 6d ff ff ff 48 c7
RSP: 0018:ffff88810b9179b0 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: 0000000000000202 RSI: 0000000000000008 RDI: ffffffff857c3680
RBP: ffff88810027d3c0 R08: ffffffff8125f2a4 R09: ffff88810b9176e7
R10: ffffed1021722edc R11: 746e756f63666572 R12: ffff88810027d388
R13: ffff88810027d3c0 R14: ffffc900005fe030 R15: ffffc900005fe048
FS: 00007fee0584a700(0000) GS:ffff88811b280000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005634a96f6c58 CR3: 0000000108ce9002 CR4: 0000000000770ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
<TASK>
bpf_refcount_acquire_impl+0xb5/0xc0
(rest of output snipped)
The patch addresses this by changing bpf_refcount_acquire_impl to use
refcount_inc_not_zero instead of refcount_inc and marking
bpf_refcount_acquire KF_RET_NULL.
For owning references, though, we know the above scenario is not possible
and thus that bpf_refcount_acquire will always succeed. Some verifier
bookkeeping is added to track "is input owning ref?" for bpf_refcount_acquire
calls and return false from is_kfunc_ret_null for bpf_refcount_acquire on
owning refs despite it being marked KF_RET_NULL.
Existing selftests using bpf_refcount_acquire are modified where
necessary to NULL-check its return value.
[0]: https://lore.kernel.org/bpf/20230415201811.343116-1-davemarchevsky@fb.com/
Fixes: d2dcc67df9 ("bpf: Migrate bpf_rbtree_add and bpf_list_push_{front,back} to possibly fail")
Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230602022647.1571784-5-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Given the pointer to struct bpf_{rb,list}_node within a local kptr and
the byte offset of that field within the kptr struct, the calculation changed
by this patch is meant to find the beginning of the kptr so that it can
be passed to bpf_obj_drop.
Unfortunately instead of doing
ptr_to_kptr = ptr_to_node_field - offset_bytes
the calculation is erroneously doing
ptr_to_ktpr = ptr_to_node_field - (offset_bytes * sizeof(struct bpf_rb_node))
or the bpf_list_node equivalent.
This patch fixes the calculation.
Fixes: d2dcc67df9 ("bpf: Migrate bpf_rbtree_add and bpf_list_push_{front,back} to possibly fail")
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230602022647.1571784-4-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In verifier.c, fixup_kfunc_call uses struct bpf_insn_aux_data's
kptr_struct_meta field to pass information about local kptr types to
various helpers and kfuncs at runtime. The recent bpf_refcount series
added a few functions to the set that need this information:
* bpf_refcount_acquire
* Needs to know where the refcount field is in order to increment
* Graph collection insert kfuncs: bpf_rbtree_add, bpf_list_push_{front,back}
* Were migrated to possibly fail by the bpf_refcount series. If
insert fails, the input node is bpf_obj_drop'd. bpf_obj_drop needs
the kptr_struct_meta in order to decr refcount and properly free
special fields.
Unfortunately the verifier handling of collection insert kfuncs was not
modified to actually populate kptr_struct_meta. Accordingly, when the
node input to those kfuncs is passed to bpf_obj_drop, it is done so
without the information necessary to decr refcount.
This patch fixes the issue by populating kptr_struct_meta for those
kfuncs.
Fixes: d2dcc67df9 ("bpf: Migrate bpf_rbtree_add and bpf_list_push_{front,back} to possibly fail")
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230602022647.1571784-3-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit d937bc3449 ("bpf: make uniform use of array->elem_size
everywhere in arraymap.c") changed array_map_gen_lookup to use
array->elem_size instead of round_up(map->value_size, 8) as the element
size when generating code to access a value in an array map.
array->elem_size, however, is not set by bpf_map_meta_alloc when
initializing an BPF_MAP_TYPE_ARRAY_OF_MAPS or BPF_MAP_TYPE_HASH_OF_MAPS.
This results in array_map_gen_lookup incorrectly outputting code that
always accesses index 0 in the array (as the index will be calculated
via a multiplication with the element size, which is incorrectly set to
0).
Set elem_size on the bpf_array object when allocating an array or hash
of maps to fix this.
Fixes: d937bc3449 ("bpf: make uniform use of array->elem_size everywhere in arraymap.c")
Signed-off-by: Rhys Rustad-Elliott <me@rhysre.net>
Link: https://lore.kernel.org/r/20230602190110.47068-2-me@rhysre.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
strlcpy() reads the entire source buffer first. This read may exceed the
destination size limit. This is both inefficient and can lead to linear
read overflows if a source string is not NUL-terminated [1]. This is not
the case here, however, in an effort to remove strlcpy() completely [2],
lets replace strlcpy() here with strscpy(). No return values were used,
so a direct replacement is safe.
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89
Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/bpf/20230530155659.309657-1-azeemshaikh38@gmail.com
syzbot reported a warning in [1] with the following stacktrace:
WARNING: CPU: 0 PID: 5005 at kernel/bpf/btf.c:1988 btf_type_id_size+0x2d9/0x9d0 kernel/bpf/btf.c:1988
...
RIP: 0010:btf_type_id_size+0x2d9/0x9d0 kernel/bpf/btf.c:1988
...
Call Trace:
<TASK>
map_check_btf kernel/bpf/syscall.c:1024 [inline]
map_create+0x1157/0x1860 kernel/bpf/syscall.c:1198
__sys_bpf+0x127f/0x5420 kernel/bpf/syscall.c:5040
__do_sys_bpf kernel/bpf/syscall.c:5162 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5160 [inline]
__x64_sys_bpf+0x79/0xc0 kernel/bpf/syscall.c:5160
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
With the following btf
[1] DECL_TAG 'a' type_id=4 component_idx=-1
[2] PTR '(anon)' type_id=0
[3] TYPE_TAG 'a' type_id=2
[4] VAR 'a' type_id=3, linkage=static
and when the bpf_attr.btf_key_type_id = 1 (DECL_TAG),
the following WARN_ON_ONCE in btf_type_id_size() is triggered:
if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) &&
!btf_type_is_var(size_type)))
return NULL;
Note that 'return NULL' is the correct behavior as we don't want
a DECL_TAG type to be used as a btf_{key,value}_type_id even
for the case like 'DECL_TAG -> STRUCT'. So there
is no correctness issue here, we just want to silence warning.
To silence the warning, I added DECL_TAG as one of kinds in
btf_type_nosize() which will cause btf_type_id_size() returning
NULL earlier without the warning.
[1] https://lore.kernel.org/bpf/000000000000e0df8d05fc75ba86@google.com/
Reported-by: syzbot+958967f249155967d42a@syzkaller.appspotmail.com
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230530205029.264910-1-yhs@fb.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2023-05-26
We've added 54 non-merge commits during the last 10 day(s) which contain
a total of 76 files changed, 2729 insertions(+), 1003 deletions(-).
The main changes are:
1) Add the capability to destroy sockets in BPF through a new kfunc,
from Aditi Ghag.
2) Support O_PATH fds in BPF_OBJ_PIN and BPF_OBJ_GET commands,
from Andrii Nakryiko.
3) Add capability for libbpf to resize datasec maps when backed via mmap,
from JP Kobryn.
4) Move all the test kfuncs for CI out of the kernel and into bpf_testmod,
from Jiri Olsa.
5) Big batch of xsk selftest improvements to prep for multi-buffer testing,
from Magnus Karlsson.
6) Show the target_{obj,btf}_id in tracing link's fdinfo and dump it
via bpftool, from Yafang Shao.
7) Various misc BPF selftest improvements to work with upcoming LLVM 17,
from Yonghong Song.
8) Extend bpftool to specify netdevice for resolving XDP hints,
from Larysa Zaremba.
9) Document masking in shift operations for the insn set document,
from Dave Thaler.
10) Extend BPF selftests to check xdp_feature support for bond driver,
from Lorenzo Bianconi.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (54 commits)
bpf: Fix bad unlock balance on freeze_mutex
libbpf: Ensure FD >= 3 during bpf_map__reuse_fd()
libbpf: Ensure libbpf always opens files with O_CLOEXEC
selftests/bpf: Check whether to run selftest
libbpf: Change var type in datasec resize func
bpf: drop unnecessary bpf_capable() check in BPF_MAP_FREEZE command
libbpf: Selftests for resizing datasec maps
libbpf: Add capability for resizing datasec maps
selftests/bpf: Add path_fd-based BPF_OBJ_PIN and BPF_OBJ_GET tests
libbpf: Add opts-based bpf_obj_pin() API and add support for path_fd
bpf: Support O_PATH FDs in BPF_OBJ_PIN and BPF_OBJ_GET commands
libbpf: Start v1.3 development cycle
bpf: Validate BPF object in BPF_OBJ_PIN before calling LSM
bpftool: Specify XDP Hints ifname when loading program
selftests/bpf: Add xdp_feature selftest for bond device
selftests/bpf: Test bpf_sock_destroy
selftests/bpf: Add helper to get port using getsockname
bpf: Add bpf_sock_destroy kfunc
bpf: Add kfunc filter function to 'struct btf_kfunc_id_set'
bpf: udp: Implement batching for sockets iterator
...
====================
Link: https://lore.kernel.org/r/20230526222747.17775-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit c4c84f6fb2 ("bpf: drop unnecessary bpf_capable() check in
BPF_MAP_FREEZE command") moved the permissions check outside of the
freeze_mutex in the map_freeze() handler. The error paths still jumps
to the err_put which tries to unlock the freeze_mutex even though it
was not locked in the first place. Fix it.
Fixes: c4c84f6fb2 ("bpf: drop unnecessary bpf_capable() check in BPF_MAP_FREEZE command")
Reported-by: syzbot+8982e75c2878b9ffeac5@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Seems like that extra bpf_capable() check in BPF_MAP_FREEZE handler was
unintentionally left when we switched to a model that all BPF map
operations should be allowed regardless of CAP_BPF (or any other
capabilities), as long as process got BPF map FD somehow.
This patch replaces bpf_capable() check in BPF_MAP_FREEZE handler with
writeable access check, given conceptually freezing the map is modifying
it: map becomes unmodifiable for subsequent updates.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230524225421.1587859-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Current UAPI of BPF_OBJ_PIN and BPF_OBJ_GET commands of bpf() syscall
forces users to specify pinning location as a string-based absolute or
relative (to current working directory) path. This has various
implications related to security (e.g., symlink-based attacks), forces
BPF FS to be exposed in the file system, which can cause races with
other applications.
One of the feedbacks we got from folks working with containers heavily
was that inability to use purely FD-based location specification was an
unfortunate limitation and hindrance for BPF_OBJ_PIN and BPF_OBJ_GET
commands. This patch closes this oversight, adding path_fd field to
BPF_OBJ_PIN and BPF_OBJ_GET UAPI, following conventions established by
*at() syscalls for dirfd + pathname combinations.
This now allows interesting possibilities like working with detached BPF
FS mount (e.g., to perform multiple pinnings without running a risk of
someone interfering with them), and generally making pinning/getting
more secure and not prone to any races and/or security attacks.
This is demonstrated by a selftest added in subsequent patch that takes
advantage of new mount APIs (fsopen, fsconfig, fsmount) to demonstrate
creating detached BPF FS mount, pinning, and then getting BPF map out of
it, all while never exposing this private instance of BPF FS to outside
worlds.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/bpf/20230523170013.728457-4-andrii@kernel.org
Do a sanity check whether provided file-to-be-pinned is actually a BPF
object (prog, map, btf) before calling security_path_mknod LSM hook. If
it's not, LSM hook doesn't have to be triggered, as the operation has no
chance of succeeding anyways.
Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/bpf/20230522232917.2454595-2-andrii@kernel.org
The LRU and LRU_PERCPU maps allocate a new element on update before locking the
target hash table bucket. Right after that the maps try to lock the bucket.
If this fails, then maps return -EBUSY to the caller without releasing the
allocated element. This makes the element untracked: it doesn't belong to
either of free lists, and it doesn't belong to the hash table, so can't be
re-used; this eventually leads to the permanent -ENOMEM on LRU map updates,
which is unexpected. Fix this by returning the element to the local free list
if bucket locking fails.
Fixes: 20b6cc34ea ("bpf: Avoid hashtab deadlock with map_locked")
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230522154558.2166815-1-aspsk@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit adds the ability to filter kfuncs to certain BPF program
types. This is required to limit bpf_sock_destroy kfunc implemented in
follow-up commits to programs with attach type 'BPF_TRACE_ITER'.
The commit adds a callback filter to 'struct btf_kfunc_id_set'. The
filter has access to the `bpf_prog` construct including its properties
such as `expected_attached_type`.
Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
Link: https://lore.kernel.org/r/20230519225157.760788-7-aditi.ghag@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
The target_btf_id can help us understand which kernel function is
linked by a tracing prog. The target_btf_id and target_obj_id have
already been exposed to userspace, so we just need to show them.
The result as follows,
$ cat /proc/10673/fdinfo/10
pos: 0
flags: 02000000
mnt_id: 15
ino: 2094
link_type: tracing
link_id: 2
prog_tag: a04f5eef06a7f555
prog_id: 13
attach_type: 24
target_obj_id: 1
target_btf_id: 13964
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230517103126.68372-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A narrow load from a 64-bit context field results in a 64-bit load
followed potentially by a 64-bit right-shift and then a bitwise AND
operation to extract the relevant data.
In the case of a 32-bit access, an immediate mask of 0xffffffff is used
to construct a 64-bit BPP_AND operation which then sign-extends the mask
value and effectively acts as a glorified no-op. For example:
0: 61 10 00 00 00 00 00 00 r0 = *(u32 *)(r1 + 0)
results in the following code generation for a 64-bit field:
ldr x7, [x7] // 64-bit load
mov x10, #0xffffffffffffffff
and x7, x7, x10
Fix the mask generation so that narrow loads always perform a 32-bit AND
operation:
ldr x7, [x7] // 64-bit load
mov w10, #0xffffffff
and w7, w7, w10
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Krzesimir Nowak <krzesimir@kinvolk.io>
Cc: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Fixes: 31fd85816d ("bpf: permits narrower load from bpf program context fields")
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230518102528.1341-1-will@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
It's trivial for user to trigger "verifier log line truncated" warning,
as verifier has a fixed-sized buffer of 1024 bytes (as of now), and there are at
least two pieces of user-provided information that can be output through
this buffer, and both can be arbitrarily sized by user:
- BTF names;
- BTF.ext source code lines strings.
Verifier log buffer should be properly sized for typical verifier state
output. But it's sort-of expected that this buffer won't be long enough
in some circumstances. So let's drop the check. In any case code will
work correctly, at worst truncating a part of a single line output.
Reported-by: syzbot+8b2a08dfbd25fd933d75@syzkaller.appspotmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230516180409.3549088-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2023-05-16
We've added 57 non-merge commits during the last 19 day(s) which contain
a total of 63 files changed, 3293 insertions(+), 690 deletions(-).
The main changes are:
1) Add precision propagation to verifier for subprogs and callbacks,
from Andrii Nakryiko.
2) Improve BPF's {g,s}setsockopt() handling with wrong option lengths,
from Stanislav Fomichev.
3) Utilize pahole v1.25 for the kernel's BTF generation to filter out
inconsistent function prototypes, from Alan Maguire.
4) Various dyn-pointer verifier improvements to relax restrictions,
from Daniel Rosenberg.
5) Add a new bpf_task_under_cgroup() kfunc for designated task,
from Feng Zhou.
6) Unblock tests for arm64 BPF CI after ftrace supporting direct call,
from Florent Revest.
7) Add XDP hint kfunc metadata for RX hash/timestamp for igc,
from Jesper Dangaard Brouer.
8) Add several new dyn-pointer kfuncs to ease their usability,
from Joanne Koong.
9) Add in-depth LRU internals description and dot function graph,
from Joe Stringer.
10) Fix KCSAN report on bpf_lru_list when accessing node->ref,
from Martin KaFai Lau.
11) Only dump unprivileged_bpf_disabled log warning upon write,
from Kui-Feng Lee.
12) Extend test_progs to directly passing allow/denylist file,
from Stephen Veiss.
13) Fix BPF trampoline memleak upon failure attaching to fentry,
from Yafang Shao.
14) Fix emitting struct bpf_tcp_sock type in vmlinux BTF,
from Yonghong Song.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (57 commits)
bpf: Fix memleak due to fentry attach failure
bpf: Remove bpf trampoline selector
bpf, arm64: Support struct arguments in the BPF trampoline
bpftool: JIT limited misreported as negative value on aarch64
bpf: fix calculation of subseq_idx during precision backtracking
bpf: Remove anonymous union in bpf_kfunc_call_arg_meta
bpf: Document EFAULT changes for sockopt
selftests/bpf: Correctly handle optlen > 4096
selftests/bpf: Update EFAULT {g,s}etsockopt selftests
bpf: Don't EFAULT for {g,s}setsockopt with wrong optlen
libbpf: fix offsetof() and container_of() to work with CO-RE
bpf: Address KCSAN report on bpf_lru_list
bpf: Add --skip_encoding_btf_inconsistent_proto, --btf_gen_optimized to pahole flags for v1.25
selftests/bpf: Accept mem from dynptr in helper funcs
bpf: verifier: Accept dynptr mem as mem in helpers
selftests/bpf: Check overflow in optional buffer
selftests/bpf: Test allowing NULL buffer in dynptr slice
bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)
selftests/bpf: Add testcase for bpf_task_under_cgroup
bpf: Add bpf_task_under_cgroup() kfunc
...
====================
Link: https://lore.kernel.org/r/20230515225603.27027-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
If it fails to attach fentry, the allocated bpf trampoline image will be
left in the system. That can be verified by checking /proc/kallsyms.
This meamleak can be verified by a simple bpf program as follows:
SEC("fentry/trap_init")
int fentry_run()
{
return 0;
}
It will fail to attach trap_init because this function is freed after
kernel init, and then we can find the trampoline image is left in the
system by checking /proc/kallsyms.
$ tail /proc/kallsyms
ffffffffc0613000 t bpf_trampoline_6442453466_1 [bpf]
ffffffffc06c3000 t bpf_trampoline_6442453466_1 [bpf]
$ bpftool btf dump file /sys/kernel/btf/vmlinux | grep "FUNC 'trap_init'"
[2522] FUNC 'trap_init' type_id=119 linkage=static
$ echo $((6442453466 & 0x7fffffff))
2522
Note that there are two left bpf trampoline images, that is because the
libbpf will fallback to raw tracepoint if -EINVAL is returned.
Fixes: e21aa34178 ("bpf: Fix fexit trampoline.")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <song@kernel.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Link: https://lore.kernel.org/bpf/20230515130849.57502-2-laoar.shao@gmail.com
After commit e21aa34178 ("bpf: Fix fexit trampoline."), the selector is only
used to indicate how many times the bpf trampoline image are updated and been
displayed in the trampoline ksym name. After the trampoline is freed, the
selector will start from 0 again. So the selector is a useless value to the
user. We can remove it.
If the user want to check whether the bpf trampoline image has been updated
or not, the user can compare the address. Each time the trampoline image is
updated, the address will change consequently. Jiri also pointed out another
issue that perf is still using the old name "bpf_trampoline_%lu", so this
change can fix the issue in perf.
Fixes: e21aa34178 ("bpf: Fix fexit trampoline.")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <song@kernel.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Link: https://lore.kernel.org/bpf/ZFvOOlrmHiY9AgXE@krava
Link: https://lore.kernel.org/bpf/20230515130849.57502-3-laoar.shao@gmail.com
Subsequent instruction index (subseq_idx) is an index of an instruction
that was verified/executed by verifier after the currently processed
instruction. It is maintained during precision backtracking processing
and is used to detect various subprog calling conditions.
This patch fixes the bug with incorrectly resetting subseq_idx to -1
when going from child state to parent state during backtracking. If we
don't maintain correct subseq_idx we can misidentify subprog calls
leading to precision tracking bugs.
One such case was triggered by test_global_funcs/global_func9 test where
global subprog call happened to be the very last instruction in parent
state, leading to subseq_idx==-1, triggering WARN_ONCE:
[ 36.045754] verifier backtracking bug
[ 36.045764] WARNING: CPU: 13 PID: 2073 at kernel/bpf/verifier.c:3503 __mark_chain_precision+0xcc6/0xde0
[ 36.046819] Modules linked in: aesni_intel(E) crypto_simd(E) cryptd(E) kvm_intel(E) kvm(E) irqbypass(E) i2c_piix4(E) serio_raw(E) i2c_core(E) crc32c_intel)
[ 36.048040] CPU: 13 PID: 2073 Comm: test_progs Tainted: G W OE 6.3.0-07976-g4d585f48ee6b-dirty #972
[ 36.048783] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
[ 36.049648] RIP: 0010:__mark_chain_precision+0xcc6/0xde0
[ 36.050038] Code: 3d 82 c6 05 bb 35 32 02 01 e8 66 21 ec ff 0f 0b b8 f2 ff ff ff e9 30 f5 ff ff 48 c7 c7 f3 61 3d 82 4c 89 0c 24 e8 4a 21 ec ff <0f> 0b 4c0
With the fix precision tracking across multiple states works correctly now:
mark_precise: frame0: last_idx 45 first_idx 38 subseq_idx -1
mark_precise: frame0: regs=r8 stack= before 44: (61) r7 = *(u32 *)(r10 -4)
mark_precise: frame0: regs=r8 stack= before 43: (85) call pc+41
mark_precise: frame0: regs=r8 stack= before 42: (07) r1 += -48
mark_precise: frame0: regs=r8 stack= before 41: (bf) r1 = r10
mark_precise: frame0: regs=r8 stack= before 40: (63) *(u32 *)(r10 -48) = r1
mark_precise: frame0: regs=r8 stack= before 39: (b4) w1 = 0
mark_precise: frame0: regs=r8 stack= before 38: (85) call pc+38
mark_precise: frame0: parent state regs=r8 stack=: R0_w=scalar() R1_w=map_value(off=4,ks=4,vs=8,imm=0) R6=1 R7_w=scalar() R8_r=P0 R10=fpm
mark_precise: frame0: last_idx 36 first_idx 28 subseq_idx 38
mark_precise: frame0: regs=r8 stack= before 36: (18) r1 = 0xffff888104f2ed14
mark_precise: frame0: regs=r8 stack= before 35: (85) call pc+33
mark_precise: frame0: regs=r8 stack= before 33: (18) r1 = 0xffff888104f2ed10
mark_precise: frame0: regs=r8 stack= before 32: (85) call pc+36
mark_precise: frame0: regs=r8 stack= before 31: (07) r1 += -4
mark_precise: frame0: regs=r8 stack= before 30: (bf) r1 = r10
mark_precise: frame0: regs=r8 stack= before 29: (63) *(u32 *)(r10 -4) = r7
mark_precise: frame0: regs=r8 stack= before 28: (4c) w7 |= w0
mark_precise: frame0: parent state regs=r8 stack=: R0_rw=scalar() R6=1 R7_rw=scalar() R8_rw=P0 R10=fp0 fp-48_r=mmmmmmmm
mark_precise: frame0: last_idx 27 first_idx 16 subseq_idx 28
mark_precise: frame0: regs=r8 stack= before 27: (85) call pc+31
mark_precise: frame0: regs=r8 stack= before 26: (b7) r1 = 0
mark_precise: frame0: regs=r8 stack= before 25: (b7) r8 = 0
Note how subseq_idx starts out as -1, then is preserved as 38 and then 28 as we
go up the parent state chain.
Reported-by: Alexei Starovoitov <ast@kernel.org>
Fixes: fde2a3882b ("bpf: support precision propagation in the presence of subprogs")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230515180710.1535018-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
For kfuncs like bpf_obj_drop and bpf_refcount_acquire - which take
user-defined types as input - the verifier needs to track the specific
type passed in when checking a particular kfunc call. This requires
tracking (btf, btf_id) tuple. In commit 7c50b1cb76
("bpf: Add bpf_refcount_acquire kfunc") I added an anonymous union with
inner structs named after the specific kfuncs tracking this information,
with the goal of making it more obvious which kfunc this data was being
tracked / expected to be tracked on behalf of.
In a recent series adding a new user of this tuple, Alexei mentioned
that he didn't like this union usage as it doesn't really help with
readability or bug-proofing ([0]). In an offline convo we agreed to
have the tuple be fields (arg_btf, arg_btf_id), with comments in
bpf_kfunc_call_arg_meta definition enumerating the uses of the fields by
kfunc-specific handling logic. Such a pattern is used by struct
bpf_reg_state without trouble.
Accordingly, this patch removes the anonymous union in favor of arg_btf
and arg_btf_id fields and comment enumerating their current uses. The
patch also removes struct btf_and_id, which was only being used by the
removed union's inner structs.
This is a mechanical change, existing linked_list and rbtree tests will
validate that correct (btf, btf_id) are being passed.
[0]: https://lore.kernel.org/bpf/20230505021707.vlyiwy57vwxglbka@dhcp-172-26-102-232.dhcp.thefacebook.com
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230510213047.1633612-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
With the way the hooks implemented right now, we have a special
condition: optval larger than PAGE_SIZE will expose only first 4k into
BPF; any modifications to the optval are ignored. If the BPF program
doesn't handle this condition by resetting optlen to 0,
the userspace will get EFAULT.
The intention of the EFAULT was to make it apparent to the
developers that the program is doing something wrong.
However, this inadvertently might affect production workloads
with the BPF programs that are not too careful (i.e., returning EFAULT
for perfectly valid setsockopt/getsockopt calls).
Let's try to minimize the chance of BPF program screwing up userspace
by ignoring the output of those BPF programs (instead of returning
EFAULT to the userspace). pr_info_once those cases to
the dmesg to help with figuring out what's going wrong.
Fixes: 0d01da6afc ("bpf: implement getsockopt and setsockopt hooks")
Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230511170456.1759459-2-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
KCSAN reported a data-race when accessing node->ref.
Although node->ref does not have to be accurate,
take this chance to use a more common READ_ONCE() and WRITE_ONCE()
pattern instead of data_race().
There is an existing bpf_lru_node_is_ref() and bpf_lru_node_set_ref().
This patch also adds bpf_lru_node_clear_ref() to do the
WRITE_ONCE(node->ref, 0) also.
==================================================================
BUG: KCSAN: data-race in __bpf_lru_list_rotate / __htab_lru_percpu_map_update_elem
write to 0xffff888137038deb of 1 bytes by task 11240 on cpu 1:
__bpf_lru_node_move kernel/bpf/bpf_lru_list.c:113 [inline]
__bpf_lru_list_rotate_active kernel/bpf/bpf_lru_list.c:149 [inline]
__bpf_lru_list_rotate+0x1bf/0x750 kernel/bpf/bpf_lru_list.c:240
bpf_lru_list_pop_free_to_local kernel/bpf/bpf_lru_list.c:329 [inline]
bpf_common_lru_pop_free kernel/bpf/bpf_lru_list.c:447 [inline]
bpf_lru_pop_free+0x638/0xe20 kernel/bpf/bpf_lru_list.c:499
prealloc_lru_pop kernel/bpf/hashtab.c:290 [inline]
__htab_lru_percpu_map_update_elem+0xe7/0x820 kernel/bpf/hashtab.c:1316
bpf_percpu_hash_update+0x5e/0x90 kernel/bpf/hashtab.c:2313
bpf_map_update_value+0x2a9/0x370 kernel/bpf/syscall.c:200
generic_map_update_batch+0x3ae/0x4f0 kernel/bpf/syscall.c:1687
bpf_map_do_batch+0x2d9/0x3d0 kernel/bpf/syscall.c:4534
__sys_bpf+0x338/0x810
__do_sys_bpf kernel/bpf/syscall.c:5096 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5094 [inline]
__x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5094
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
read to 0xffff888137038deb of 1 bytes by task 11241 on cpu 0:
bpf_lru_node_set_ref kernel/bpf/bpf_lru_list.h:70 [inline]
__htab_lru_percpu_map_update_elem+0x2f1/0x820 kernel/bpf/hashtab.c:1332
bpf_percpu_hash_update+0x5e/0x90 kernel/bpf/hashtab.c:2313
bpf_map_update_value+0x2a9/0x370 kernel/bpf/syscall.c:200
generic_map_update_batch+0x3ae/0x4f0 kernel/bpf/syscall.c:1687
bpf_map_do_batch+0x2d9/0x3d0 kernel/bpf/syscall.c:4534
__sys_bpf+0x338/0x810
__do_sys_bpf kernel/bpf/syscall.c:5096 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5094 [inline]
__x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5094
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
value changed: 0x01 -> 0x00
Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11241 Comm: syz-executor.3 Not tainted 6.3.0-rc7-syzkaller-00136-g6a66fdd29ea1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
==================================================================
Reported-by: syzbot+ebe648a84e8784763f82@syzkaller.appspotmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230511043748.1384166-1-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This allows using memory retrieved from dynptrs with helper functions
that accept ARG_PTR_TO_MEM. For instance, results from bpf_dynptr_data
can be passed along to bpf_strncmp.
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Link: https://lore.kernel.org/r/20230506013134.2492210-5-drosen@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_dynptr_slice(_rw) uses a user provided buffer if it can not provide
a pointer to a block of contiguous memory. This buffer is unused in the
case of local dynptrs, and may be unused in other cases as well. There
is no need to require the buffer, as the kfunc can just return NULL if
it was needed and not provided.
This adds another kfunc annotation, __opt, which combines with __sz and
__szk to allow the buffer associated with the size to be NULL. If the
buffer is NULL, the verifier does not check that the buffer is of
sufficient size.
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Link: https://lore.kernel.org/r/20230506013134.2492210-2-drosen@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a kfunc that's similar to the bpf_current_task_under_cgroup.
The difference is that it is a designated task.
When hook sched related functions, sometimes it is necessary to
specify a task instead of the current task.
Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230506031545.35991-2-zhoufeng.zf@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add support precision backtracking in the presence of subprogram frames in
jump history.
This means supporting a few different kinds of subprogram invocation
situations, all requiring a slightly different handling in precision
backtracking handling logic:
- static subprogram calls;
- global subprogram calls;
- callback-calling helpers/kfuncs.
For each of those we need to handle a few precision propagation cases:
- what to do with precision of subprog returns (r0);
- what to do with precision of input arguments;
- for all of them callee-saved registers in caller function should be
propagated ignoring subprog/callback part of jump history.
N.B. Async callback-calling helpers (currently only
bpf_timer_set_callback()) are transparent to all this because they set
a separate async callback environment and thus callback's history is not
shared with main program's history. So as far as all the changes in this
commit goes, such helper is just a regular helper.
Let's look at all these situation in more details. Let's start with
static subprogram being called, using an exxerpt of a simple main
program and its static subprog, indenting subprog's frame slightly to
make everything clear.
frame 0 frame 1 precision set
======= ======= =============
9: r6 = 456;
10: r1 = 123; fr0: r6
11: call pc+10; fr0: r1, r6
22: r0 = r1; fr0: r6; fr1: r1
23: exit fr0: r6; fr1: r0
12: r1 = <map_pointer> fr0: r0, r6
13: r1 += r0; fr0: r0, r6
14: r1 += r6; fr0: r6
15: exit
As can be seen above main function is passing 123 as single argument to
an identity (`return x;`) subprog. Returned value is used to adjust map
pointer offset, which forces r0 to be marked as precise. Then
instruction #14 does the same for callee-saved r6, which will have to be
backtracked all the way to instruction #9. For brevity, precision sets
for instruction #13 and #14 are combined in the diagram above.
First, for subprog calls, r0 returned from subprog (in frame 0) has to
go into subprog's frame 1, and should be cleared from frame 0. So we go
back into subprog's frame knowing we need to mark r0 precise. We then
see that insn #22 sets r0 from r1, so now we care about marking r1
precise. When we pop up from subprog's frame back into caller at
insn #11 we keep r1, as it's an argument-passing register, so we eventually
find `10: r1 = 123;` and satify precision propagation chain for insn #13.
This example demonstrates two sets of rules:
- r0 returned after subprog call has to be moved into subprog's r0 set;
- *static* subprog arguments (r1-r5) are moved back to caller precision set.
Let's look at what happens with callee-saved precision propagation. Insn #14
mark r6 as precise. When we get into subprog's frame, we keep r6 in
frame 0's precision set *only*. Subprog itself has its own set of
independent r6-r10 registers and is not affected. When we eventually
made our way out of subprog frame we keep r6 in precision set until we
reach `9: r6 = 456;`, satisfying propagation. r6-r10 propagation is
perhaps the simplest aspect, it always stays in its original frame.
That's pretty much all we have to do to support precision propagation
across *static subprog* invocation.
Let's look at what happens when we have global subprog invocation.
frame 0 frame 1 precision set
======= ======= =============
9: r6 = 456;
10: r1 = 123; fr0: r6
11: call pc+10; # global subprog fr0: r6
12: r1 = <map_pointer> fr0: r0, r6
13: r1 += r0; fr0: r0, r6
14: r1 += r6; fr0: r6;
15: exit
Starting from insn #13, r0 has to be precise. We backtrack all the way
to insn #11 (call pc+10) and see that subprog is global, so was already
validated in isolation. As opposed to static subprog, global subprog
always returns unknown scalar r0, so that satisfies precision
propagation and we drop r0 from precision set. We are done for insns #13.
Now for insn #14. r6 is in precision set, we backtrack to `call pc+10;`.
Here we need to recognize that this is effectively both exit and entry
to global subprog, which means we stay in caller's frame. So we carry on
with r6 still in precision set, until we satisfy it at insn #9. The only
hard part with global subprogs is just knowing when it's a global func.
Lastly, callback-calling helpers and kfuncs do simulate subprog calls,
so jump history will have subprog instructions in between caller
program's instructions, but the rules of propagating r0 and r1-r5
differ, because we don't actually directly call callback. We actually
call helper/kfunc, which at runtime will call subprog, so the only
difference between normal helper/kfunc handling is that we need to make
sure to skip callback simulatinog part of jump history.
Let's look at an example to make this clearer.
frame 0 frame 1 precision set
======= ======= =============
8: r6 = 456;
9: r1 = 123; fr0: r6
10: r2 = &callback; fr0: r6
11: call bpf_loop; fr0: r6
22: r0 = r1; fr0: r6 fr1:
23: exit fr0: r6 fr1:
12: r1 = <map_pointer> fr0: r0, r6
13: r1 += r0; fr0: r0, r6
14: r1 += r6; fr0: r6;
15: exit
Again, insn #13 forces r0 to be precise. As soon as we get to `23: exit`
we see that this isn't actually a static subprog call (it's `call
bpf_loop;` helper call instead). So we clear r0 from precision set.
For callee-saved register, there is no difference: it stays in frame 0's
precision set, we go through insn #22 and #23, ignoring them until we
get back to caller frame 0, eventually satisfying precision backtrack
logic at insn #8 (`r6 = 456;`).
Assuming callback needed to set r0 as precise at insn #23, we'd
backtrack to insn #22, switching from r0 to r1, and then at the point
when we pop back to frame 0 at insn #11, we'll clear r1-r5 from
precision set, as we don't really do a subprog call directly, so there
is no input argument precision propagation.
That's pretty much it. With these changes, it seems like the only still
unsupported situation for precision backpropagation is the case when
program is accessing stack through registers other than r10. This is
still left as unsupported (though rare) case for now.
As for results. For selftests, few positive changes for bigger programs,
cls_redirect in dynptr variant benefitting the most:
[vmuser@archvm bpf]$ ./veristat -C ~/subprog-precise-before-results.csv ~/subprog-precise-after-results.csv -f @veristat.cfg -e file,prog,insns -f 'insns_diff!=0'
File Program Insns (A) Insns (B) Insns (DIFF)
---------------------------------------- ------------- --------- --------- ----------------
pyperf600_bpf_loop.bpf.linked1.o on_event 2060 2002 -58 (-2.82%)
test_cls_redirect_dynptr.bpf.linked1.o cls_redirect 15660 2914 -12746 (-81.39%)
test_cls_redirect_subprogs.bpf.linked1.o cls_redirect 61620 59088 -2532 (-4.11%)
xdp_synproxy_kern.bpf.linked1.o syncookie_tc 109980 86278 -23702 (-21.55%)
xdp_synproxy_kern.bpf.linked1.o syncookie_xdp 97716 85147 -12569 (-12.86%)
Cilium progress don't really regress. They don't use subprogs and are
mostly unaffected, but some other fixes and improvements could have
changed something. This doesn't appear to be the case:
[vmuser@archvm bpf]$ ./veristat -C ~/subprog-precise-before-results-cilium.csv ~/subprog-precise-after-results-cilium.csv -e file,prog,insns -f 'insns_diff!=0'
File Program Insns (A) Insns (B) Insns (DIFF)
------------- ------------------------------ --------- --------- ------------
bpf_host.o tail_nodeport_nat_ingress_ipv6 4983 5003 +20 (+0.40%)
bpf_lxc.o tail_nodeport_nat_ingress_ipv6 4983 5003 +20 (+0.40%)
bpf_overlay.o tail_nodeport_nat_ingress_ipv6 4983 5003 +20 (+0.40%)
bpf_xdp.o tail_handle_nat_fwd_ipv6 12475 12504 +29 (+0.23%)
bpf_xdp.o tail_nodeport_nat_ingress_ipv6 6363 6371 +8 (+0.13%)
Looking at (somewhat anonymized) Meta production programs, we see mostly
insignificant variation in number of instructions, with one program
(syar_bind6_protect6) benefitting the most at -17%.
[vmuser@archvm bpf]$ ./veristat -C ~/subprog-precise-before-results-fbcode.csv ~/subprog-precise-after-results-fbcode.csv -e prog,insns -f 'insns_diff!=0'
Program Insns (A) Insns (B) Insns (DIFF)
------------------------ --------- --------- ----------------
on_request_context_event 597 585 -12 (-2.01%)
read_async_py_stack 43789 43657 -132 (-0.30%)
read_sync_py_stack 35041 37599 +2558 (+7.30%)
rrm_usdt 946 940 -6 (-0.63%)
sysarmor_inet6_bind 28863 28249 -614 (-2.13%)
sysarmor_inet_bind 28845 28240 -605 (-2.10%)
syar_bind4_protect4 154145 147640 -6505 (-4.22%)
syar_bind6_protect6 165242 137088 -28154 (-17.04%)
syar_task_exit_setgid 21289 19720 -1569 (-7.37%)
syar_task_exit_setuid 21290 19721 -1569 (-7.37%)
do_uprobe 19967 19413 -554 (-2.77%)
tw_twfw_ingress 215877 204833 -11044 (-5.12%)
tw_twfw_tc_in 215877 204833 -11044 (-5.12%)
But checking duration (wall clock) differences, that is the actual time taken
by verifier to validate programs, we see a sometimes dramatic improvements, all
the way to about 16x improvements:
[vmuser@archvm bpf]$ ./veristat -C ~/subprog-precise-before-results-meta.csv ~/subprog-precise-after-results-meta.csv -e prog,duration -s duration_diff^ | head -n20
Program Duration (us) (A) Duration (us) (B) Duration (us) (DIFF)
---------------------------------------- ----------------- ----------------- --------------------
tw_twfw_ingress 4488374 272836 -4215538 (-93.92%)
tw_twfw_tc_in 4339111 268175 -4070936 (-93.82%)
tw_twfw_egress 3521816 270751 -3251065 (-92.31%)
tw_twfw_tc_eg 3472878 284294 -3188584 (-91.81%)
balancer_ingress 343119 291391 -51728 (-15.08%)
syar_bind6_protect6 78992 64782 -14210 (-17.99%)
ttls_tc_ingress 11739 8176 -3563 (-30.35%)
kprobe__security_inode_link 13864 11341 -2523 (-18.20%)
read_sync_py_stack 21927 19442 -2485 (-11.33%)
read_async_py_stack 30444 28136 -2308 (-7.58%)
syar_task_exit_setuid 10256 8440 -1816 (-17.71%)
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When precision backtracking bails out due to some unsupported sequence
of instructions (e.g., stack access through register other than r10), we
need to mark all SCALAR registers as precise to be safe. Currently,
though, we mark SCALARs precise only starting from the state we detected
unsupported condition, which could be one of the parent states of the
actual current state. This will leave some registers potentially not
marked as precise, even though they should. So make sure we start
marking scalars as precise from current state (env->cur_state).
Further, we don't currently detect a situation when we end up with some
stack slots marked as needing precision, but we ran out of available
states to find the instructions that populate those stack slots. This is
akin the `i >= func->allocated_stack / BPF_REG_SIZE` check and should be
handled similarly by falling back to marking all SCALARs precise. Add
this check when we run out of states.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-8-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Fix propagate_precision() logic to perform propagation of all necessary
registers and stack slots across all active frames *in one batch step*.
Doing this for each register/slot in each individual frame is wasteful,
but the main problem is that backtracking of instruction in any frame
except the deepest one just doesn't work. This is due to backtracking
logic relying on jump history, and available jump history always starts
(or ends, depending how you view it) in current frame. So, if
prog A (frame #0) called subprog B (frame #1) and we need to propagate
precision of, say, register R6 (callee-saved) within frame #0, we
actually don't even know where jump history that corresponds to prog
A even starts. We'd need to skip subprog part of jump history first to
be able to do this.
Luckily, with struct backtrack_state and __mark_chain_precision()
handling bitmasks tracking/propagation across all active frames at the
same time (added in previous patch), propagate_precision() can be both
fixed and sped up by setting all the necessary bits across all frames
and then performing one __mark_chain_precision() pass. This makes it
unnecessary to skip subprog parts of jump history.
We also improve logging along the way, to clearly specify which
registers' and slots' precision markings are propagated within which
frame. Each frame will have dedicated line and all registers and stack
slots from that frame will be reported in format similar to precision
backtrack regs/stack logging. E.g.:
frame 1: propagating r1,r2,r3,fp-8,fp-16
frame 0: propagating r3,r9,fp-120
Fixes: 529409ea92 ("bpf: propagate precision across all frames, not just the last one")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Teach __mark_chain_precision logic to maintain register/stack masks
across all active frames when going from child state to parent state.
Currently this should be mostly no-op, as precision backtracking usually
bails out when encountering subprog entry/exit.
It's not very apparent from the diff due to increased indentation, but
the logic remains the same, except everything is done on specific `fr`
frame index. Calls to bt_clear_reg() and bt_clear_slot() are replaced
with frame-specific bt_clear_frame_reg() and bt_clear_frame_slot(),
where frame index is passed explicitly, instead of using current frame
number.
We also adjust logging to emit affected frame number. And we also add
better logging of human-readable register and stack slot masks, similar
to previous patch.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add helper to format register and stack masks in more human-readable
format. Adjust logging a bit during backtrack propagation and especially
during forcing precision fallback logic to make it clearer what's going
on (with log_level=2, of course), and also start reporting affected
frame depth. This is in preparation for having more than one active
frame later when precision propagation between subprog calls is added.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add struct backtrack_state and straightforward API around it to keep
track of register and stack masks used and maintained during precision
backtracking process. Having this logic separately allow to keep
high-level backtracking algorithm cleaner, but also it sets us up to
cleanly keep track of register and stack masks per frame, allowing (with
some further logic adjustments) to perform precision backpropagation
across multiple frames (i.e., subprog calls).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When handling instructions that read register slots, mark relevant stack
slots as scratched so that verifier log would contain those slots' states, in
addition to currently emitted registers with stack slot offsets.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Only print the warning message if you are writing to
"/proc/sys/kernel/unprivileged_bpf_disabled".
The kernel may print an annoying warning when you read
"/proc/sys/kernel/unprivileged_bpf_disabled" saying
WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible
via Spectre v2 BHB attacks!
However, this message is only meaningful when the feature is
disabled or enabled.
Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20230502181418.308479-1-kuifeng@meta.com
* cpuset changes including the fix for an incorrect interaction with CPU
hotplug and an optimization.
* Other doc and cosmetic changes.
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Merge tag 'cgroup-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
- cpuset changes including the fix for an incorrect interaction with
CPU hotplug and an optimization
- Other doc and cosmetic changes
* tag 'cgroup-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
docs: cgroup-v1/cpusets: update libcgroup project link
cgroup/cpuset: Minor updates to test_cpuset_prs.sh
cgroup/cpuset: Include offline CPUs when tasks' cpumasks in top_cpuset are updated
cgroup/cpuset: Skip task update if hotplug doesn't affect current cpuset
cpuset: Clean up cpuset_node_allowed
cgroup: bpf: use cgroup_lock()/cgroup_unlock() wrappers
The cloned dynptr will point to the same data as its parent dynptr,
with the same type, offset, size and read-only properties.
Any writes to a dynptr will be reflected across all instances
(by 'instance', this means any dynptrs that point to the same
underlying data).
Please note that data slice and dynptr invalidations will affect all
instances as well. For example, if bpf_dynptr_write() is called on an
skb-type dynptr, all data slices of dynptr instances to that skb
will be invalidated as well (eg data slices of any clones, parents,
grandparents, ...). Another example is if a ringbuf dynptr is submitted,
any instance of that dynptr will be invalidated.
Changing the view of the dynptr (eg advancing the offset or
trimming the size) will only affect that dynptr and not affect any
other instances.
One example use case where cloning may be helpful is for hashing or
iterating through dynptr data. Cloning will allow the user to maintain
the original view of the dynptr for future use, while also allowing
views to smaller subsets of the data after the offset is advanced or the
size is trimmed.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230420071414.570108-5-joannelkoong@gmail.com
bpf_dynptr_size returns the number of usable bytes in a dynptr.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20230420071414.570108-4-joannelkoong@gmail.com
bpf_dynptr_is_null returns true if the dynptr is null / invalid
(determined by whether ptr->data is NULL), else false if
the dynptr is a valid dynptr.
bpf_dynptr_is_rdonly returns true if the dynptr is read-only,
else false if the dynptr is read-writable. If the dynptr is
null / invalid, false is returned by default.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20230420071414.570108-3-joannelkoong@gmail.com
Add a new kfunc
int bpf_dynptr_adjust(struct bpf_dynptr_kern *ptr, u32 start, u32 end);
which adjusts the dynptr to reflect the new [start, end) interval.
In particular, it advances the offset of the dynptr by "start" bytes,
and if end is less than the size of the dynptr, then this will trim the
dynptr accordingly.
Adjusting the dynptr interval may be useful in certain situations.
For example, when hashing which takes in generic dynptrs, if the dynptr
points to a struct but only a certain memory region inside the struct
should be hashed, adjust can be used to narrow in on the
specific region to hash.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230420071414.570108-2-joannelkoong@gmail.com
Core
----
- Introduce a config option to tweak MAX_SKB_FRAGS. Increasing the
default value allows for better BIG TCP performances.
- Reduce compound page head access for zero-copy data transfers.
- RPS/RFS improvements, avoiding unneeded NET_RX_SOFTIRQ when possible.
- Threaded NAPI improvements, adding defer skb free support and unneeded
softirq avoidance.
- Address dst_entry reference count scalability issues, via false
sharing avoidance and optimize refcount tracking.
- Add lockless accesses annotation to sk_err[_soft].
- Optimize again the skb struct layout.
- Extends the skb drop reasons to make it usable by multiple
subsystems.
- Better const qualifier awareness for socket casts.
BPF
---
- Add skb and XDP typed dynptrs which allow BPF programs for more
ergonomic and less brittle iteration through data and variable-sized
accesses.
- Add a new BPF netfilter program type and minimal support to hook
BPF programs to netfilter hooks such as prerouting or forward.
- Add more precise memory usage reporting for all BPF map types.
- Adds support for using {FOU,GUE} encap with an ipip device operating
in collect_md mode and add a set of BPF kfuncs for controlling encap
params.
- Allow BPF programs to detect at load time whether a particular kfunc
exists or not, and also add support for this in light skeleton.
- Bigger batch of BPF verifier improvements to prepare for upcoming BPF
open-coded iterators allowing for less restrictive looping capabilities.
- Rework RCU enforcement in the verifier, add kptr_rcu and enforce BPF
programs to NULL-check before passing such pointers into kfunc.
- Add support for kptrs in percpu hashmaps, percpu LRU hashmaps and in
local storage maps.
- Enable RCU semantics for task BPF kptrs and allow referenced kptr
tasks to be stored in BPF maps.
- Add support for refcounted local kptrs to the verifier for allowing
shared ownership, useful for adding a node to both the BPF list and
rbtree.
- Add BPF verifier support for ST instructions in convert_ctx_access()
which will help new -mcpu=v4 clang flag to start emitting them.
- Add ARM32 USDT support to libbpf.
- Improve bpftool's visual program dump which produces the control
flow graph in a DOT format by adding C source inline annotations.
Protocols
---------
- IPv4: Allow adding to IPv4 address a 'protocol' tag. Such value
indicates the provenance of the IP address.
- IPv6: optimize route lookup, dropping unneeded R/W lock acquisition.
- Add the handshake upcall mechanism, allowing the user-space
to implement generic TLS handshake on kernel's behalf.
- Bridge: support per-{Port, VLAN} neighbor suppression, increasing
resilience to nodes failures.
- SCTP: add support for Fair Capacity and Weighted Fair Queueing
schedulers.
- MPTCP: delay first subflow allocation up to its first usage. This
will allow for later better LSM interaction.
- xfrm: Remove inner/outer modes from input/output path. These are
not needed anymore.
- WiFi:
- reduced neighbor report (RNR) handling for AP mode
- HW timestamping support
- support for randomized auth/deauth TA for PASN privacy
- per-link debugfs for multi-link
- TC offload support for mac80211 drivers
- mac80211 mesh fast-xmit and fast-rx support
- enable Wi-Fi 7 (EHT) mesh support
Netfilter
---------
- Add nf_tables 'brouting' support, to force a packet to be routed
instead of being bridged.
- Update bridge netfilter and ovs conntrack helpers to handle
IPv6 Jumbo packets properly, i.e. fetch the packet length
from hop-by-hop extension header. This is needed for BIT TCP
support.
- The iptables 32bit compat interface isn't compiled in by default
anymore.
- Move ip(6)tables builtin icmp matches to the udptcp one.
This has the advantage that icmp/icmpv6 match doesn't load the
iptables/ip6tables modules anymore when iptables-nft is used.
- Extended netlink error report for netdevice in flowtables and
netdev/chains. Allow for incrementally add/delete devices to netdev
basechain. Allow to create netdev chain without device.
Driver API
----------
- Remove redundant Device Control Error Reporting Enable, as PCI core
has already error reporting enabled at enumeration time.
- Move Multicast DB netlink handlers to core, allowing devices other
then bridge to use them.
- Allow the page_pool to directly recycle the pages from safely
localized NAPI.
- Implement lockless TX queue stop/wake combo macros, allowing for
further code de-duplication and sanitization.
- Add YNL support for user headers and struct attrs.
- Add partial YNL specification for devlink.
- Add partial YNL specification for ethtool.
- Add tc-mqprio and tc-taprio support for preemptible traffic classes.
- Add tx push buf len param to ethtool, specifies the maximum number
of bytes of a transmitted packet a driver can push directly to the
underlying device.
- Add basic LED support for switch/phy.
- Add NAPI documentation, stop relaying on external links.
- Convert dsa_master_ioctl() to netdev notifier. This is a preparatory
work to make the hardware timestamping layer selectable by user
space.
- Add transceiver support and improve the error messages for CAN-FD
controllers.
New hardware / drivers
----------------------
- Ethernet:
- AMD/Pensando core device support
- MediaTek MT7981 SoC
- MediaTek MT7988 SoC
- Broadcom BCM53134 embedded switch
- Texas Instruments CPSW9G ethernet switch
- Qualcomm EMAC3 DWMAC ethernet
- StarFive JH7110 SoC
- NXP CBTX ethernet PHY
- WiFi:
- Apple M1 Pro/Max devices
- RealTek rtl8710bu/rtl8188gu
- RealTek rtl8822bs, rtl8822cs and rtl8821cs SDIO chipset
- Bluetooth:
- Realtek RTL8821CS, RTL8851B, RTL8852BS
- Mediatek MT7663, MT7922
- NXP w8997
- Actions Semi ATS2851
- QTI WCN6855
- Marvell 88W8997
- Can:
- STMicroelectronics bxcan stm32f429
Drivers
-------
- Ethernet NICs:
- Intel (1G, icg):
- add tracking and reporting of QBV config errors.
- add support for configuring max SDU for each Tx queue.
- Intel (100G, ice):
- refactor mailbox overflow detection to support Scalable IOV
- GNSS interface optimization
- Intel (i40e):
- support XDP multi-buffer
- nVidia/Mellanox:
- add the support for linux bridge multicast offload
- enable TC offload for egress and engress MACVLAN over bond
- add support for VxLAN GBP encap/decap flows offload
- extend packet offload to fully support libreswan
- support tunnel mode in mlx5 IPsec packet offload
- extend XDP multi-buffer support
- support MACsec VLAN offload
- add support for dynamic msix vectors allocation
- drop RX page_cache and fully use page_pool
- implement thermal zone to report NIC temperature
- Netronome/Corigine:
- add support for multi-zone conntrack offload
- Solarflare/Xilinx:
- support offloading TC VLAN push/pop actions to the MAE
- support TC decap rules
- support unicast PTP
- Other NICs:
- Broadcom (bnxt): enforce software based freq adjustments only
on shared PHC NIC
- RealTek (r8169): refactor to addess ASPM issues during NAPI poll.
- Micrel (lan8841): add support for PTP_PF_PEROUT
- Cadence (macb): enable PTP unicast
- Engleder (tsnep): add XDP socket zero-copy support
- virtio-net: implement exact header length guest feature
- veth: add page_pool support for page recycling
- vxlan: add MDB data path support
- gve: add XDP support for GQI-QPL format
- geneve: accept every ethertype
- macvlan: allow some packets to bypass broadcast queue
- mana: add support for jumbo frame
- Ethernet high-speed switches:
- Microchip (sparx5): Add support for TC flower templates.
- Ethernet embedded switches:
- Broadcom (b54):
- configure 6318 and 63268 RGMII ports
- Marvell (mv88e6xxx):
- faster C45 bus scan
- Microchip:
- lan966x:
- add support for IS1 VCAP
- better TX/RX from/to CPU performances
- ksz9477: add ETS Qdisc support
- ksz8: enhance static MAC table operations and error handling
- sama7g5: add PTP capability
- NXP (ocelot):
- add support for external ports
- add support for preemptible traffic classes
- Texas Instruments:
- add CPSWxG SGMII support for J7200 and J721E
- Intel WiFi (iwlwifi):
- preparation for Wi-Fi 7 EHT and multi-link support
- EHT (Wi-Fi 7) sniffer support
- hardware timestamping support for some devices/firwmares
- TX beacon protection on newer hardware
- Qualcomm 802.11ax WiFi (ath11k):
- MU-MIMO parameters support
- ack signal support for management packets
- RealTek WiFi (rtw88):
- SDIO bus support
- better support for some SDIO devices
(e.g. MAC address from efuse)
- RealTek WiFi (rtw89):
- HW scan support for 8852b
- better support for 6 GHz scanning
- support for various newer firmware APIs
- framework firmware backwards compatibility
- MediaTek WiFi (mt76):
- P2P support
- mesh A-MSDU support
- EHT (Wi-Fi 7) support
- coredump support
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Merge tag 'net-next-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Paolo Abeni:
"Core:
- Introduce a config option to tweak MAX_SKB_FRAGS. Increasing the
default value allows for better BIG TCP performances
- Reduce compound page head access for zero-copy data transfers
- RPS/RFS improvements, avoiding unneeded NET_RX_SOFTIRQ when
possible
- Threaded NAPI improvements, adding defer skb free support and
unneeded softirq avoidance
- Address dst_entry reference count scalability issues, via false
sharing avoidance and optimize refcount tracking
- Add lockless accesses annotation to sk_err[_soft]
- Optimize again the skb struct layout
- Extends the skb drop reasons to make it usable by multiple
subsystems
- Better const qualifier awareness for socket casts
BPF:
- Add skb and XDP typed dynptrs which allow BPF programs for more
ergonomic and less brittle iteration through data and
variable-sized accesses
- Add a new BPF netfilter program type and minimal support to hook
BPF programs to netfilter hooks such as prerouting or forward
- Add more precise memory usage reporting for all BPF map types
- Adds support for using {FOU,GUE} encap with an ipip device
operating in collect_md mode and add a set of BPF kfuncs for
controlling encap params
- Allow BPF programs to detect at load time whether a particular
kfunc exists or not, and also add support for this in light
skeleton
- Bigger batch of BPF verifier improvements to prepare for upcoming
BPF open-coded iterators allowing for less restrictive looping
capabilities
- Rework RCU enforcement in the verifier, add kptr_rcu and enforce
BPF programs to NULL-check before passing such pointers into kfunc
- Add support for kptrs in percpu hashmaps, percpu LRU hashmaps and
in local storage maps
- Enable RCU semantics for task BPF kptrs and allow referenced kptr
tasks to be stored in BPF maps
- Add support for refcounted local kptrs to the verifier for allowing
shared ownership, useful for adding a node to both the BPF list and
rbtree
- Add BPF verifier support for ST instructions in
convert_ctx_access() which will help new -mcpu=v4 clang flag to
start emitting them
- Add ARM32 USDT support to libbpf
- Improve bpftool's visual program dump which produces the control
flow graph in a DOT format by adding C source inline annotations
Protocols:
- IPv4: Allow adding to IPv4 address a 'protocol' tag. Such value
indicates the provenance of the IP address
- IPv6: optimize route lookup, dropping unneeded R/W lock acquisition
- Add the handshake upcall mechanism, allowing the user-space to
implement generic TLS handshake on kernel's behalf
- Bridge: support per-{Port, VLAN} neighbor suppression, increasing
resilience to nodes failures
- SCTP: add support for Fair Capacity and Weighted Fair Queueing
schedulers
- MPTCP: delay first subflow allocation up to its first usage. This
will allow for later better LSM interaction
- xfrm: Remove inner/outer modes from input/output path. These are
not needed anymore
- WiFi:
- reduced neighbor report (RNR) handling for AP mode
- HW timestamping support
- support for randomized auth/deauth TA for PASN privacy
- per-link debugfs for multi-link
- TC offload support for mac80211 drivers
- mac80211 mesh fast-xmit and fast-rx support
- enable Wi-Fi 7 (EHT) mesh support
Netfilter:
- Add nf_tables 'brouting' support, to force a packet to be routed
instead of being bridged
- Update bridge netfilter and ovs conntrack helpers to handle IPv6
Jumbo packets properly, i.e. fetch the packet length from
hop-by-hop extension header. This is needed for BIT TCP support
- The iptables 32bit compat interface isn't compiled in by default
anymore
- Move ip(6)tables builtin icmp matches to the udptcp one. This has
the advantage that icmp/icmpv6 match doesn't load the
iptables/ip6tables modules anymore when iptables-nft is used
- Extended netlink error report for netdevice in flowtables and
netdev/chains. Allow for incrementally add/delete devices to netdev
basechain. Allow to create netdev chain without device
Driver API:
- Remove redundant Device Control Error Reporting Enable, as PCI core
has already error reporting enabled at enumeration time
- Move Multicast DB netlink handlers to core, allowing devices other
then bridge to use them
- Allow the page_pool to directly recycle the pages from safely
localized NAPI
- Implement lockless TX queue stop/wake combo macros, allowing for
further code de-duplication and sanitization
- Add YNL support for user headers and struct attrs
- Add partial YNL specification for devlink
- Add partial YNL specification for ethtool
- Add tc-mqprio and tc-taprio support for preemptible traffic classes
- Add tx push buf len param to ethtool, specifies the maximum number
of bytes of a transmitted packet a driver can push directly to the
underlying device
- Add basic LED support for switch/phy
- Add NAPI documentation, stop relaying on external links
- Convert dsa_master_ioctl() to netdev notifier. This is a
preparatory work to make the hardware timestamping layer selectable
by user space
- Add transceiver support and improve the error messages for CAN-FD
controllers
New hardware / drivers:
- Ethernet:
- AMD/Pensando core device support
- MediaTek MT7981 SoC
- MediaTek MT7988 SoC
- Broadcom BCM53134 embedded switch
- Texas Instruments CPSW9G ethernet switch
- Qualcomm EMAC3 DWMAC ethernet
- StarFive JH7110 SoC
- NXP CBTX ethernet PHY
- WiFi:
- Apple M1 Pro/Max devices
- RealTek rtl8710bu/rtl8188gu
- RealTek rtl8822bs, rtl8822cs and rtl8821cs SDIO chipset
- Bluetooth:
- Realtek RTL8821CS, RTL8851B, RTL8852BS
- Mediatek MT7663, MT7922
- NXP w8997
- Actions Semi ATS2851
- QTI WCN6855
- Marvell 88W8997
- Can:
- STMicroelectronics bxcan stm32f429
Drivers:
- Ethernet NICs:
- Intel (1G, icg):
- add tracking and reporting of QBV config errors
- add support for configuring max SDU for each Tx queue
- Intel (100G, ice):
- refactor mailbox overflow detection to support Scalable IOV
- GNSS interface optimization
- Intel (i40e):
- support XDP multi-buffer
- nVidia/Mellanox:
- add the support for linux bridge multicast offload
- enable TC offload for egress and engress MACVLAN over bond
- add support for VxLAN GBP encap/decap flows offload
- extend packet offload to fully support libreswan
- support tunnel mode in mlx5 IPsec packet offload
- extend XDP multi-buffer support
- support MACsec VLAN offload
- add support for dynamic msix vectors allocation
- drop RX page_cache and fully use page_pool
- implement thermal zone to report NIC temperature
- Netronome/Corigine:
- add support for multi-zone conntrack offload
- Solarflare/Xilinx:
- support offloading TC VLAN push/pop actions to the MAE
- support TC decap rules
- support unicast PTP
- Other NICs:
- Broadcom (bnxt): enforce software based freq adjustments only on
shared PHC NIC
- RealTek (r8169): refactor to addess ASPM issues during NAPI poll
- Micrel (lan8841): add support for PTP_PF_PEROUT
- Cadence (macb): enable PTP unicast
- Engleder (tsnep): add XDP socket zero-copy support
- virtio-net: implement exact header length guest feature
- veth: add page_pool support for page recycling
- vxlan: add MDB data path support
- gve: add XDP support for GQI-QPL format
- geneve: accept every ethertype
- macvlan: allow some packets to bypass broadcast queue
- mana: add support for jumbo frame
- Ethernet high-speed switches:
- Microchip (sparx5): Add support for TC flower templates
- Ethernet embedded switches:
- Broadcom (b54):
- configure 6318 and 63268 RGMII ports
- Marvell (mv88e6xxx):
- faster C45 bus scan
- Microchip:
- lan966x:
- add support for IS1 VCAP
- better TX/RX from/to CPU performances
- ksz9477: add ETS Qdisc support
- ksz8: enhance static MAC table operations and error handling
- sama7g5: add PTP capability
- NXP (ocelot):
- add support for external ports
- add support for preemptible traffic classes
- Texas Instruments:
- add CPSWxG SGMII support for J7200 and J721E
- Intel WiFi (iwlwifi):
- preparation for Wi-Fi 7 EHT and multi-link support
- EHT (Wi-Fi 7) sniffer support
- hardware timestamping support for some devices/firwmares
- TX beacon protection on newer hardware
- Qualcomm 802.11ax WiFi (ath11k):
- MU-MIMO parameters support
- ack signal support for management packets
- RealTek WiFi (rtw88):
- SDIO bus support
- better support for some SDIO devices (e.g. MAC address from
efuse)
- RealTek WiFi (rtw89):
- HW scan support for 8852b
- better support for 6 GHz scanning
- support for various newer firmware APIs
- framework firmware backwards compatibility
- MediaTek WiFi (mt76):
- P2P support
- mesh A-MSDU support
- EHT (Wi-Fi 7) support
- coredump support"
* tag 'net-next-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2078 commits)
net: phy: hide the PHYLIB_LEDS knob
net: phy: marvell-88x2222: remove unnecessary (void*) conversions
tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp.
net: amd: Fix link leak when verifying config failed
net: phy: marvell: Fix inconsistent indenting in led_blink_set
lan966x: Don't use xdp_frame when action is XDP_TX
tsnep: Add XDP socket zero-copy TX support
tsnep: Add XDP socket zero-copy RX support
tsnep: Move skb receive action to separate function
tsnep: Add functions for queue enable/disable
tsnep: Rework TX/RX queue initialization
tsnep: Replace modulo operation with mask
net: phy: dp83867: Add led_brightness_set support
net: phy: Fix reading LED reg property
drivers: nfc: nfcsim: remove return value check of `dev_dir`
net: phy: dp83867: Remove unnecessary (void*) conversions
net: ethtool: coalesce: try to make user settings stick twice
net: mana: Check if netdev/napi_alloc_frag returns single page
net: mana: Rename mana_refill_rxoob and remove some empty lines
net: veth: add page_pool stats
...
ACPI:
* Improve error reporting when failing to manage SDEI on AGDI device
removal
Assembly routines:
* Improve register constraints so that the compiler can make use of
the zero register instead of moving an immediate #0 into a GPR
* Allow the compiler to allocate the registers used for CAS
instructions
CPU features and system registers:
* Cleanups to the way in which CPU features are identified from the
ID register fields
* Extend system register definition generation to handle Enum types
when defining shared register fields
* Generate definitions for new _EL2 registers and add new fields
for ID_AA64PFR1_EL1
* Allow SVE to be disabled separately from SME on the kernel
command-line
Tracing:
* Support for "direct calls" in ftrace, which enables BPF tracing
for arm64
Kdump:
* Don't bother unmapping the crashkernel from the linear mapping,
which then allows us to use huge (block) mappings and reduce
TLB pressure when a crashkernel is loaded.
Memory management:
* Try again to remove data cache invalidation from the coherent DMA
allocation path
* Simplify the fixmap code by mapping at page granularity
* Allow the kfence pool to be allocated early, preventing the rest
of the linear mapping from being forced to page granularity
Perf and PMU:
* Move CPU PMU code out to drivers/perf/ where it can be reused
by the 32-bit ARM architecture when running on ARMv8 CPUs
* Fix race between CPU PMU probing and pKVM host de-privilege
* Add support for Apple M2 CPU PMU
* Adjust the generic PERF_COUNT_HW_BRANCH_INSTRUCTIONS event
dynamically, depending on what the CPU actually supports
* Minor fixes and cleanups to system PMU drivers
Stack tracing:
* Use the XPACLRI instruction to strip PAC from pointers, rather
than rolling our own function in C
* Remove redundant PAC removal for toolchains that handle this in
their builtins
* Make backtracing more resilient in the face of instrumentation
Miscellaneous:
* Fix single-step with KGDB
* Remove harmless warning when 'nokaslr' is passed on the kernel
command-line
* Minor fixes and cleanups across the board
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon:
"ACPI:
- Improve error reporting when failing to manage SDEI on AGDI device
removal
Assembly routines:
- Improve register constraints so that the compiler can make use of
the zero register instead of moving an immediate #0 into a GPR
- Allow the compiler to allocate the registers used for CAS
instructions
CPU features and system registers:
- Cleanups to the way in which CPU features are identified from the
ID register fields
- Extend system register definition generation to handle Enum types
when defining shared register fields
- Generate definitions for new _EL2 registers and add new fields for
ID_AA64PFR1_EL1
- Allow SVE to be disabled separately from SME on the kernel
command-line
Tracing:
- Support for "direct calls" in ftrace, which enables BPF tracing for
arm64
Kdump:
- Don't bother unmapping the crashkernel from the linear mapping,
which then allows us to use huge (block) mappings and reduce TLB
pressure when a crashkernel is loaded.
Memory management:
- Try again to remove data cache invalidation from the coherent DMA
allocation path
- Simplify the fixmap code by mapping at page granularity
- Allow the kfence pool to be allocated early, preventing the rest of
the linear mapping from being forced to page granularity
Perf and PMU:
- Move CPU PMU code out to drivers/perf/ where it can be reused by
the 32-bit ARM architecture when running on ARMv8 CPUs
- Fix race between CPU PMU probing and pKVM host de-privilege
- Add support for Apple M2 CPU PMU
- Adjust the generic PERF_COUNT_HW_BRANCH_INSTRUCTIONS event
dynamically, depending on what the CPU actually supports
- Minor fixes and cleanups to system PMU drivers
Stack tracing:
- Use the XPACLRI instruction to strip PAC from pointers, rather than
rolling our own function in C
- Remove redundant PAC removal for toolchains that handle this in
their builtins
- Make backtracing more resilient in the face of instrumentation
Miscellaneous:
- Fix single-step with KGDB
- Remove harmless warning when 'nokaslr' is passed on the kernel
command-line
- Minor fixes and cleanups across the board"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (72 commits)
KVM: arm64: Ensure CPU PMU probes before pKVM host de-privilege
arm64: kexec: include reboot.h
arm64: delete dead code in this_cpu_set_vectors()
arm64/cpufeature: Use helper macro to specify ID register for capabilites
drivers/perf: hisi: add NULL check for name
drivers/perf: hisi: Remove redundant initialized of pmu->name
arm64/cpufeature: Consistently use symbolic constants for min_field_value
arm64/cpufeature: Pull out helper for CPUID register definitions
arm64/sysreg: Convert HFGITR_EL2 to automatic generation
ACPI: AGDI: Improve error reporting for problems during .remove()
arm64: kernel: Fix kernel warning when nokaslr is passed to commandline
perf/arm-cmn: Fix port detection for CMN-700
arm64: kgdb: Set PSTATE.SS to 1 to re-enable single-step
arm64: move PAC masks to <asm/pointer_auth.h>
arm64: use XPACLRI to strip PAC
arm64: avoid redundant PAC stripping in __builtin_return_address()
arm64/sme: Fix some comments of ARM SME
arm64/signal: Alloc tpidr2 sigframe after checking system_supports_tpidr2()
arm64/signal: Use system_supports_tpidr2() to check TPIDR2
arm64/idreg: Don't disable SME when disabling SVE
...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs fget updates from Al Viro:
"fget() to fdget() conversions"
* tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fuse_dev_ioctl(): switch to fdget()
cgroup_get_from_fd(): switch to fdget_raw()
bpf: switch to fdget_raw()
build_mount_idmapped(): switch to fdget()
kill the last remaining user of proc_ns_fget()
SVM-SEV: convert the rest of fget() uses to fdget() in there
convert sgx_set_attribute() to fdget()/fdput()
convert setns(2) to fdget()/fdput()
The tracing recursion prevention mechanism must be protected by rcu, that
leaves __rcu_read_{lock,unlock} unprotected by this mechanism. If we trace
them, the recursion will happen. Let's add them into the btf id deny list.
When CONFIG_PREEMPT_RCU is enabled, it can be reproduced with a simple bpf
program as such:
SEC("fentry/__rcu_read_lock")
int fentry_run()
{
return 0;
}
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230424161104.3737-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
As reported by Kumar in [0], the shared ownership implementation for BPF
programs has some race conditions which need to be addressed before it
can safely be used. This patch does so in a minimal way instead of
ripping out shared ownership entirely, as proper fixes for the issues
raised will follow ASAP, at which point this patch's commit can be
reverted to re-enable shared ownership.
The patch removes the ability to call bpf_refcount_acquire_impl from BPF
programs. Programs can only bump refcount and obtain a new owning
reference using this kfunc, so removing the ability to call it
effectively disables shared ownership.
Instead of changing success / failure expectations for
bpf_refcount-related selftests, this patch just disables them from
running for now.
[0]: https://lore.kernel.org/bpf/d7hyspcow5wtjcmw4fugdgyp3fwhljwuscp3xyut5qnwivyeru@ysdq543otzv2/
Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230424204321.2680232-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2023-04-21
We've added 71 non-merge commits during the last 8 day(s) which contain
a total of 116 files changed, 13397 insertions(+), 8896 deletions(-).
The main changes are:
1) Add a new BPF netfilter program type and minimal support to hook
BPF programs to netfilter hooks such as prerouting or forward,
from Florian Westphal.
2) Fix race between btf_put and btf_idr walk which caused a deadlock,
from Alexei Starovoitov.
3) Second big batch to migrate test_verifier unit tests into test_progs
for ease of readability and debugging, from Eduard Zingerman.
4) Add support for refcounted local kptrs to the verifier for allowing
shared ownership, useful for adding a node to both the BPF list and
rbtree, from Dave Marchevsky.
5) Migrate bpf_for(), bpf_for_each() and bpf_repeat() macros from BPF
selftests into libbpf-provided bpf_helpers.h header and improve
kfunc handling, from Andrii Nakryiko.
6) Support 64-bit pointers to kfuncs needed for archs like s390x,
from Ilya Leoshkevich.
7) Support BPF progs under getsockopt with a NULL optval,
from Stanislav Fomichev.
8) Improve verifier u32 scalar equality checking in order to enable
LLVM transformations which earlier had to be disabled specifically
for BPF backend, from Yonghong Song.
9) Extend bpftool's struct_ops object loading to support links,
from Kui-Feng Lee.
10) Add xsk selftest follow-up fixes for hugepage allocated umem,
from Magnus Karlsson.
11) Support BPF redirects from tc BPF to ifb devices,
from Daniel Borkmann.
12) Add BPF support for integer type when accessing variable length
arrays, from Feng Zhou.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (71 commits)
selftests/bpf: verifier/value_ptr_arith converted to inline assembly
selftests/bpf: verifier/value_illegal_alu converted to inline assembly
selftests/bpf: verifier/unpriv converted to inline assembly
selftests/bpf: verifier/subreg converted to inline assembly
selftests/bpf: verifier/spin_lock converted to inline assembly
selftests/bpf: verifier/sock converted to inline assembly
selftests/bpf: verifier/search_pruning converted to inline assembly
selftests/bpf: verifier/runtime_jit converted to inline assembly
selftests/bpf: verifier/regalloc converted to inline assembly
selftests/bpf: verifier/ref_tracking converted to inline assembly
selftests/bpf: verifier/map_ptr_mixing converted to inline assembly
selftests/bpf: verifier/map_in_map converted to inline assembly
selftests/bpf: verifier/lwt converted to inline assembly
selftests/bpf: verifier/loops1 converted to inline assembly
selftests/bpf: verifier/jeq_infer_not_null converted to inline assembly
selftests/bpf: verifier/direct_packet_access converted to inline assembly
selftests/bpf: verifier/d_path converted to inline assembly
selftests/bpf: verifier/ctx converted to inline assembly
selftests/bpf: verifier/btf_ctx_access converted to inline assembly
selftests/bpf: verifier/bpf_get_stack converted to inline assembly
...
====================
Link: https://lore.kernel.org/r/20230421211035.9111-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This adds minimal support for BPF_PROG_TYPE_NETFILTER bpf programs
that will be invoked via the NF_HOOK() points in the ip stack.
Invocation incurs an indirect call. This is not a necessity: Its
possible to add 'DEFINE_BPF_DISPATCHER(nf_progs)' and handle the
program invocation with the same method already done for xdp progs.
This isn't done here to keep the size of this chunk down.
Verifier restricts verdicts to either DROP or ACCEPT.
Signed-off-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/20230421170300.24115-3-fw@strlen.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add bpf_link support skeleton. To keep this reviewable, no bpf program
can be invoked yet, if a program is attached only a c-stub is called and
not the actual bpf program.
Defaults to 'y' if both netfilter and bpf syscall are enabled in kconfig.
Uapi example usage:
union bpf_attr attr = { };
attr.link_create.prog_fd = progfd;
attr.link_create.attach_type = 0; /* unused */
attr.link_create.netfilter.pf = PF_INET;
attr.link_create.netfilter.hooknum = NF_INET_LOCAL_IN;
attr.link_create.netfilter.priority = -128;
err = bpf(BPF_LINK_CREATE, &attr, sizeof(attr));
... this would attach progfd to ipv4:input hook.
Such hook gets removed automatically if the calling program exits.
BPF_NETFILTER program invocation is added in followup change.
NF_HOOK_OP_BPF enum will eventually be read from nfnetlink_hook, it
allows to tell userspace which program is attached at the given hook
when user runs 'nft hook list' command rather than just the priority
and not-very-helpful 'this hook runs a bpf prog but I can't tell which
one'.
Will also be used to disallow registration of two bpf programs with
same priority in a followup patch.
v4: arm32 cmpxchg only supports 32bit operand
s/prio/priority/
v3: restrict prog attachment to ip/ip6 for now, lets lift restrictions if
more use cases pop up (arptables, ebtables, netdev ingress/egress etc).
Signed-off-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/20230421170300.24115-2-fw@strlen.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When calculating the address of the refcount_t struct within a local
kptr, bpf_refcount_acquire_impl should add refcount_off bytes to the
address of the local kptr. Due to some missing parens, the function is
incorrectly adding sizeof(refcount_t) * refcount_off bytes. This patch
fixes the calculation.
Due to the incorrect calculation, bpf_refcount_acquire_impl was trying
to refcount_inc some memory well past the end of local kptrs, resulting
in kasan and refcount complaints, as reported in [0]. In that thread,
Florian and Eduard discovered that bpf selftests written in the new
style - with __success and an expected __retval, specifically - were
not actually being run. As a result, selftests added in bpf_refcount
series weren't really exercising this behavior, and thus didn't unearth
the bug.
With this fixed behavior it's safe to revert commit 7c4b96c000
("selftests/bpf: disable program test run for progs/refcounted_kptr.c"),
this patch does so.
[0] https://lore.kernel.org/bpf/ZEEp+j22imoN6rn9@strlen.de/
Fixes: 7c50b1cb76 ("bpf: Add bpf_refcount_acquire kfunc")
Reported-by: Florian Westphal <fw@strlen.de>
Reported-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20230421074431.3548349-1-davemarchevsky@fb.com
Florian and Eduard reported hard dead lock:
[ 58.433327] _raw_spin_lock_irqsave+0x40/0x50
[ 58.433334] btf_put+0x43/0x90
[ 58.433338] bpf_find_btf_id+0x157/0x240
[ 58.433353] btf_parse_fields+0x921/0x11c0
This happens since btf->refcount can be 1 at the time of btf_put() and
btf_put() will call btf_free_id() which will try to grab btf_idr_lock
and will dead lock.
Avoid the issue by doing btf_put() without locking.
Fixes: 3d78417b60 ("bpf: Add bpf_btf_find_by_name_kind() helper.")
Fixes: 1e89106da2 ("bpf: Add bpf_core_add_cands() and wire it into bpf_core_apply_relo_insn().")
Reported-by: Florian Westphal <fw@strlen.de>
Reported-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20230421014901.70908-1-alexei.starovoitov@gmail.com
Juan Jose et al reported an issue found via fuzzing where the verifier's
pruning logic prematurely marks a program path as safe.
Consider the following program:
0: (b7) r6 = 1024
1: (b7) r7 = 0
2: (b7) r8 = 0
3: (b7) r9 = -2147483648
4: (97) r6 %= 1025
5: (05) goto pc+0
6: (bd) if r6 <= r9 goto pc+2
7: (97) r6 %= 1
8: (b7) r9 = 0
9: (bd) if r6 <= r9 goto pc+1
10: (b7) r6 = 0
11: (b7) r0 = 0
12: (63) *(u32 *)(r10 -4) = r0
13: (18) r4 = 0xffff888103693400 // map_ptr(ks=4,vs=48)
15: (bf) r1 = r4
16: (bf) r2 = r10
17: (07) r2 += -4
18: (85) call bpf_map_lookup_elem#1
19: (55) if r0 != 0x0 goto pc+1
20: (95) exit
21: (77) r6 >>= 10
22: (27) r6 *= 8192
23: (bf) r1 = r0
24: (0f) r0 += r6
25: (79) r3 = *(u64 *)(r0 +0)
26: (7b) *(u64 *)(r1 +0) = r3
27: (95) exit
The verifier treats this as safe, leading to oob read/write access due
to an incorrect verifier conclusion:
func#0 @0
0: R1=ctx(off=0,imm=0) R10=fp0
0: (b7) r6 = 1024 ; R6_w=1024
1: (b7) r7 = 0 ; R7_w=0
2: (b7) r8 = 0 ; R8_w=0
3: (b7) r9 = -2147483648 ; R9_w=-2147483648
4: (97) r6 %= 1025 ; R6_w=scalar()
5: (05) goto pc+0
6: (bd) if r6 <= r9 goto pc+2 ; R6_w=scalar(umin=18446744071562067969,var_off=(0xffffffff00000000; 0xffffffff)) R9_w=-2147483648
7: (97) r6 %= 1 ; R6_w=scalar()
8: (b7) r9 = 0 ; R9=0
9: (bd) if r6 <= r9 goto pc+1 ; R6=scalar(umin=1) R9=0
10: (b7) r6 = 0 ; R6_w=0
11: (b7) r0 = 0 ; R0_w=0
12: (63) *(u32 *)(r10 -4) = r0
last_idx 12 first_idx 9
regs=1 stack=0 before 11: (b7) r0 = 0
13: R0_w=0 R10=fp0 fp-8=0000????
13: (18) r4 = 0xffff8ad3886c2a00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0
17: (07) r2 += -4 ; R2_w=fp-4
18: (85) call bpf_map_lookup_elem#1 ; R0=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0)
19: (55) if r0 != 0x0 goto pc+1 ; R0=0
20: (95) exit
from 19 to 21: R0=map_value(off=0,ks=4,vs=48,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm????
21: (77) r6 >>= 10 ; R6_w=0
22: (27) r6 *= 8192 ; R6_w=0
23: (bf) r1 = r0 ; R0=map_value(off=0,ks=4,vs=48,imm=0) R1_w=map_value(off=0,ks=4,vs=48,imm=0)
24: (0f) r0 += r6
last_idx 24 first_idx 19
regs=40 stack=0 before 23: (bf) r1 = r0
regs=40 stack=0 before 22: (27) r6 *= 8192
regs=40 stack=0 before 21: (77) r6 >>= 10
regs=40 stack=0 before 19: (55) if r0 != 0x0 goto pc+1
parent didn't have regs=40 stack=0 marks: R0_rw=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0) R6_rw=P0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm????
last_idx 18 first_idx 9
regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
regs=40 stack=0 before 17: (07) r2 += -4
regs=40 stack=0 before 16: (bf) r2 = r10
regs=40 stack=0 before 15: (bf) r1 = r4
regs=40 stack=0 before 13: (18) r4 = 0xffff8ad3886c2a00
regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
regs=40 stack=0 before 11: (b7) r0 = 0
regs=40 stack=0 before 10: (b7) r6 = 0
25: (79) r3 = *(u64 *)(r0 +0) ; R0_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar()
26: (7b) *(u64 *)(r1 +0) = r3 ; R1_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar()
27: (95) exit
from 9 to 11: R1=ctx(off=0,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0
11: (b7) r0 = 0 ; R0_w=0
12: (63) *(u32 *)(r10 -4) = r0
last_idx 12 first_idx 11
regs=1 stack=0 before 11: (b7) r0 = 0
13: R0_w=0 R10=fp0 fp-8=0000????
13: (18) r4 = 0xffff8ad3886c2a00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0
17: (07) r2 += -4 ; R2_w=fp-4
18: (85) call bpf_map_lookup_elem#1
frame 0: propagating r6
last_idx 19 first_idx 11
regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
regs=40 stack=0 before 17: (07) r2 += -4
regs=40 stack=0 before 16: (bf) r2 = r10
regs=40 stack=0 before 15: (bf) r1 = r4
regs=40 stack=0 before 13: (18) r4 = 0xffff8ad3886c2a00
regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
regs=40 stack=0 before 11: (b7) r0 = 0
parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_r=P0 R7=0 R8=0 R9=0 R10=fp0
last_idx 9 first_idx 9
regs=40 stack=0 before 9: (bd) if r6 <= r9 goto pc+1
parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_rw=Pscalar() R7_w=0 R8_w=0 R9_rw=0 R10=fp0
last_idx 8 first_idx 0
regs=40 stack=0 before 8: (b7) r9 = 0
regs=40 stack=0 before 7: (97) r6 %= 1
regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
regs=40 stack=0 before 5: (05) goto pc+0
regs=40 stack=0 before 4: (97) r6 %= 1025
regs=40 stack=0 before 3: (b7) r9 = -2147483648
regs=40 stack=0 before 2: (b7) r8 = 0
regs=40 stack=0 before 1: (b7) r7 = 0
regs=40 stack=0 before 0: (b7) r6 = 1024
19: safe
frame 0: propagating r6
last_idx 9 first_idx 0
regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
regs=40 stack=0 before 5: (05) goto pc+0
regs=40 stack=0 before 4: (97) r6 %= 1025
regs=40 stack=0 before 3: (b7) r9 = -2147483648
regs=40 stack=0 before 2: (b7) r8 = 0
regs=40 stack=0 before 1: (b7) r7 = 0
regs=40 stack=0 before 0: (b7) r6 = 1024
from 6 to 9: safe
verification time 110 usec
stack depth 4
processed 36 insns (limit 1000000) max_states_per_insn 0 total_states 3 peak_states 3 mark_read 2
The verifier considers this program as safe by mistakenly pruning unsafe
code paths. In the above func#0, code lines 0-10 are of interest. In line
0-3 registers r6 to r9 are initialized with known scalar values. In line 4
the register r6 is reset to an unknown scalar given the verifier does not
track modulo operations. Due to this, the verifier can also not determine
precisely which branches in line 6 and 9 are taken, therefore it needs to
explore them both.
As can be seen, the verifier starts with exploring the false/fall-through
paths first. The 'from 19 to 21' path has both r6=0 and r9=0 and the pointer
arithmetic on r0 += r6 is therefore considered safe. Given the arithmetic,
r6 is correctly marked for precision tracking where backtracking kicks in
where it walks back the current path all the way where r6 was set to 0 in
the fall-through branch.
Next, the pruning logics pops the path 'from 9 to 11' from the stack. Also
here, the state of the registers is the same, that is, r6=0 and r9=0, so
that at line 19 the path can be pruned as it is considered safe. It is
interesting to note that the conditional in line 9 turned r6 into a more
precise state, that is, in the fall-through path at the beginning of line
10, it is R6=scalar(umin=1), and in the branch-taken path (which is analyzed
here) at the beginning of line 11, r6 turned into a known const r6=0 as
r9=0 prior to that and therefore (unsigned) r6 <= 0 concludes that r6 must
be 0 (**):
[...] ; R6_w=scalar()
9: (bd) if r6 <= r9 goto pc+1 ; R6=scalar(umin=1) R9=0
[...]
from 9 to 11: R1=ctx(off=0,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0
[...]
The next path is 'from 6 to 9'. The verifier considers the old and current
state equivalent, and therefore prunes the search incorrectly. Looking into
the two states which are being compared by the pruning logic at line 9, the
old state consists of R6_rwD=Pscalar() R9_rwD=0 R10=fp0 and the new state
consists of R1=ctx(off=0,imm=0) R6_w=scalar(umax=18446744071562067968)
R7_w=0 R8_w=0 R9_w=-2147483648 R10=fp0. While r6 had the reg->precise flag
correctly set in the old state, r9 did not. Both r6'es are considered as
equivalent given the old one is a superset of the current, more precise one,
however, r9's actual values (0 vs 0x80000000) mismatch. Given the old r9
did not have reg->precise flag set, the verifier does not consider the
register as contributing to the precision state of r6, and therefore it
considered both r9 states as equivalent. However, for this specific pruned
path (which is also the actual path taken at runtime), register r6 will be
0x400 and r9 0x80000000 when reaching line 21, thus oob-accessing the map.
The purpose of precision tracking is to initially mark registers (including
spilled ones) as imprecise to help verifier's pruning logic finding equivalent
states it can then prune if they don't contribute to the program's safety
aspects. For example, if registers are used for pointer arithmetic or to pass
constant length to a helper, then the verifier sets reg->precise flag and
backtracks the BPF program instruction sequence and chain of verifier states
to ensure that the given register or stack slot including their dependencies
are marked as precisely tracked scalar. This also includes any other registers
and slots that contribute to a tracked state of given registers/stack slot.
This backtracking relies on recorded jmp_history and is able to traverse
entire chain of parent states. This process ends only when all the necessary
registers/slots and their transitive dependencies are marked as precise.
The backtrack_insn() is called from the current instruction up to the first
instruction, and its purpose is to compute a bitmask of registers and stack
slots that need precision tracking in the parent's verifier state. For example,
if a current instruction is r6 = r7, then r6 needs precision after this
instruction and r7 needs precision before this instruction, that is, in the
parent state. Hence for the latter r7 is marked and r6 unmarked.
For the class of jmp/jmp32 instructions, backtrack_insn() today only looks
at call and exit instructions and for all other conditionals the masks
remain as-is. However, in the given situation register r6 has a dependency
on r9 (as described above in **), so also that one needs to be marked for
precision tracking. In other words, if an imprecise register influences a
precise one, then the imprecise register should also be marked precise.
Meaning, in the parent state both dest and src register need to be tracked
for precision and therefore the marking must be more conservative by setting
reg->precise flag for both. The precision propagation needs to cover both
for the conditional: if the src reg was marked but not the dst reg and vice
versa.
After the fix the program is correctly rejected:
func#0 @0
0: R1=ctx(off=0,imm=0) R10=fp0
0: (b7) r6 = 1024 ; R6_w=1024
1: (b7) r7 = 0 ; R7_w=0
2: (b7) r8 = 0 ; R8_w=0
3: (b7) r9 = -2147483648 ; R9_w=-2147483648
4: (97) r6 %= 1025 ; R6_w=scalar()
5: (05) goto pc+0
6: (bd) if r6 <= r9 goto pc+2 ; R6_w=scalar(umin=18446744071562067969,var_off=(0xffffffff80000000; 0x7fffffff),u32_min=-2147483648) R9_w=-2147483648
7: (97) r6 %= 1 ; R6_w=scalar()
8: (b7) r9 = 0 ; R9=0
9: (bd) if r6 <= r9 goto pc+1 ; R6=scalar(umin=1) R9=0
10: (b7) r6 = 0 ; R6_w=0
11: (b7) r0 = 0 ; R0_w=0
12: (63) *(u32 *)(r10 -4) = r0
last_idx 12 first_idx 9
regs=1 stack=0 before 11: (b7) r0 = 0
13: R0_w=0 R10=fp0 fp-8=0000????
13: (18) r4 = 0xffff9290dc5bfe00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0
17: (07) r2 += -4 ; R2_w=fp-4
18: (85) call bpf_map_lookup_elem#1 ; R0=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0)
19: (55) if r0 != 0x0 goto pc+1 ; R0=0
20: (95) exit
from 19 to 21: R0=map_value(off=0,ks=4,vs=48,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm????
21: (77) r6 >>= 10 ; R6_w=0
22: (27) r6 *= 8192 ; R6_w=0
23: (bf) r1 = r0 ; R0=map_value(off=0,ks=4,vs=48,imm=0) R1_w=map_value(off=0,ks=4,vs=48,imm=0)
24: (0f) r0 += r6
last_idx 24 first_idx 19
regs=40 stack=0 before 23: (bf) r1 = r0
regs=40 stack=0 before 22: (27) r6 *= 8192
regs=40 stack=0 before 21: (77) r6 >>= 10
regs=40 stack=0 before 19: (55) if r0 != 0x0 goto pc+1
parent didn't have regs=40 stack=0 marks: R0_rw=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0) R6_rw=P0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm????
last_idx 18 first_idx 9
regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
regs=40 stack=0 before 17: (07) r2 += -4
regs=40 stack=0 before 16: (bf) r2 = r10
regs=40 stack=0 before 15: (bf) r1 = r4
regs=40 stack=0 before 13: (18) r4 = 0xffff9290dc5bfe00
regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
regs=40 stack=0 before 11: (b7) r0 = 0
regs=40 stack=0 before 10: (b7) r6 = 0
25: (79) r3 = *(u64 *)(r0 +0) ; R0_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar()
26: (7b) *(u64 *)(r1 +0) = r3 ; R1_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar()
27: (95) exit
from 9 to 11: R1=ctx(off=0,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0
11: (b7) r0 = 0 ; R0_w=0
12: (63) *(u32 *)(r10 -4) = r0
last_idx 12 first_idx 11
regs=1 stack=0 before 11: (b7) r0 = 0
13: R0_w=0 R10=fp0 fp-8=0000????
13: (18) r4 = 0xffff9290dc5bfe00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0
17: (07) r2 += -4 ; R2_w=fp-4
18: (85) call bpf_map_lookup_elem#1
frame 0: propagating r6
last_idx 19 first_idx 11
regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
regs=40 stack=0 before 17: (07) r2 += -4
regs=40 stack=0 before 16: (bf) r2 = r10
regs=40 stack=0 before 15: (bf) r1 = r4
regs=40 stack=0 before 13: (18) r4 = 0xffff9290dc5bfe00
regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
regs=40 stack=0 before 11: (b7) r0 = 0
parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_r=P0 R7=0 R8=0 R9=0 R10=fp0
last_idx 9 first_idx 9
regs=40 stack=0 before 9: (bd) if r6 <= r9 goto pc+1
parent didn't have regs=240 stack=0 marks: R1=ctx(off=0,imm=0) R6_rw=Pscalar() R7_w=0 R8_w=0 R9_rw=P0 R10=fp0
last_idx 8 first_idx 0
regs=240 stack=0 before 8: (b7) r9 = 0
regs=40 stack=0 before 7: (97) r6 %= 1
regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
regs=240 stack=0 before 5: (05) goto pc+0
regs=240 stack=0 before 4: (97) r6 %= 1025
regs=240 stack=0 before 3: (b7) r9 = -2147483648
regs=40 stack=0 before 2: (b7) r8 = 0
regs=40 stack=0 before 1: (b7) r7 = 0
regs=40 stack=0 before 0: (b7) r6 = 1024
19: safe
from 6 to 9: R1=ctx(off=0,imm=0) R6_w=scalar(umax=18446744071562067968) R7_w=0 R8_w=0 R9_w=-2147483648 R10=fp0
9: (bd) if r6 <= r9 goto pc+1
last_idx 9 first_idx 0
regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
regs=240 stack=0 before 5: (05) goto pc+0
regs=240 stack=0 before 4: (97) r6 %= 1025
regs=240 stack=0 before 3: (b7) r9 = -2147483648
regs=40 stack=0 before 2: (b7) r8 = 0
regs=40 stack=0 before 1: (b7) r7 = 0
regs=40 stack=0 before 0: (b7) r6 = 1024
last_idx 9 first_idx 0
regs=200 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
regs=240 stack=0 before 5: (05) goto pc+0
regs=240 stack=0 before 4: (97) r6 %= 1025
regs=240 stack=0 before 3: (b7) r9 = -2147483648
regs=40 stack=0 before 2: (b7) r8 = 0
regs=40 stack=0 before 1: (b7) r7 = 0
regs=40 stack=0 before 0: (b7) r6 = 1024
11: R6=scalar(umax=18446744071562067968) R9=-2147483648
11: (b7) r0 = 0 ; R0_w=0
12: (63) *(u32 *)(r10 -4) = r0
last_idx 12 first_idx 11
regs=1 stack=0 before 11: (b7) r0 = 0
13: R0_w=0 R10=fp0 fp-8=0000????
13: (18) r4 = 0xffff9290dc5bfe00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0
17: (07) r2 += -4 ; R2_w=fp-4
18: (85) call bpf_map_lookup_elem#1 ; R0_w=map_value_or_null(id=3,off=0,ks=4,vs=48,imm=0)
19: (55) if r0 != 0x0 goto pc+1 ; R0_w=0
20: (95) exit
from 19 to 21: R0=map_value(off=0,ks=4,vs=48,imm=0) R6=scalar(umax=18446744071562067968) R7=0 R8=0 R9=-2147483648 R10=fp0 fp-8=mmmm????
21: (77) r6 >>= 10 ; R6_w=scalar(umax=18014398507384832,var_off=(0x0; 0x3fffffffffffff))
22: (27) r6 *= 8192 ; R6_w=scalar(smax=9223372036854767616,umax=18446744073709543424,var_off=(0x0; 0xffffffffffffe000),s32_max=2147475456,u32_max=-8192)
23: (bf) r1 = r0 ; R0=map_value(off=0,ks=4,vs=48,imm=0) R1_w=map_value(off=0,ks=4,vs=48,imm=0)
24: (0f) r0 += r6
last_idx 24 first_idx 21
regs=40 stack=0 before 23: (bf) r1 = r0
regs=40 stack=0 before 22: (27) r6 *= 8192
regs=40 stack=0 before 21: (77) r6 >>= 10
parent didn't have regs=40 stack=0 marks: R0_rw=map_value(off=0,ks=4,vs=48,imm=0) R6_r=Pscalar(umax=18446744071562067968) R7=0 R8=0 R9=-2147483648 R10=fp0 fp-8=mmmm????
last_idx 19 first_idx 11
regs=40 stack=0 before 19: (55) if r0 != 0x0 goto pc+1
regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
regs=40 stack=0 before 17: (07) r2 += -4
regs=40 stack=0 before 16: (bf) r2 = r10
regs=40 stack=0 before 15: (bf) r1 = r4
regs=40 stack=0 before 13: (18) r4 = 0xffff9290dc5bfe00
regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
regs=40 stack=0 before 11: (b7) r0 = 0
parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_rw=Pscalar(umax=18446744071562067968) R7_w=0 R8_w=0 R9_w=-2147483648 R10=fp0
last_idx 9 first_idx 0
regs=40 stack=0 before 9: (bd) if r6 <= r9 goto pc+1
regs=240 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
regs=240 stack=0 before 5: (05) goto pc+0
regs=240 stack=0 before 4: (97) r6 %= 1025
regs=240 stack=0 before 3: (b7) r9 = -2147483648
regs=40 stack=0 before 2: (b7) r8 = 0
regs=40 stack=0 before 1: (b7) r7 = 0
regs=40 stack=0 before 0: (b7) r6 = 1024
math between map_value pointer and register with unbounded min value is not allowed
verification time 886 usec
stack depth 4
processed 49 insns (limit 1000000) max_states_per_insn 1 total_states 5 peak_states 5 mark_read 2
Fixes: b5dc0163d8 ("bpf: precise scalar_value tracking")
Reported-by: Juan Jose Lopez Jaimez <jjlopezjaimez@google.com>
Reported-by: Meador Inge <meadori@google.com>
Reported-by: Simon Scannell <simonscannell@google.com>
Reported-by: Nenad Stojanovski <thenenadx@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Co-developed-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Reviewed-by: Juan Jose Lopez Jaimez <jjlopezjaimez@google.com>
Reviewed-by: Meador Inge <meadori@google.com>
Reviewed-by: Simon Scannell <simonscannell@google.com>
Make it possible to load lirc program type with just CAP_BPF. There is
nothing exceptional about lirc programs that means they require
SYS_CAP_ADMIN.
In order to attach or detach a lirc program type you need permission to
open /dev/lirc0; if you have permission to do that, you can alter all
sorts of lirc receiving options. Changing the IR protocol decoder is no
different.
Right now on a typical distribution /dev/lirc devices are only
read/write by root. Ideally we would make them group read/write like
other devices so that local users can use them without becoming root.
Signed-off-by: Sean Young <sean@mess.org>
Link: https://lore.kernel.org/r/ZD0ArKpwnDBJZsrE@gofer.mess.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We've managed to improve the UX for kptrs significantly over the last 9
months. All of the existing use cases which previously had KF_KPTR_GET
kfuncs (struct bpf_cpumask *, struct task_struct *, and struct cgroup *)
have all been updated to be synchronized using RCU. In other words,
their KF_KPTR_GET kfuncs have been removed in favor of KF_RCU |
KF_ACQUIRE kfuncs, with the pointers themselves also being readable from
maps in an RCU read region thanks to the types being RCU safe.
While KF_KPTR_GET was a logical starting point for kptrs, it's become
clear that they're not the correct abstraction. KF_KPTR_GET is a flag
that essentially does nothing other than enforcing that the argument to
a function is a pointer to a referenced kptr map value. At first glance,
that's a useful thing to guarantee to a kfunc. It gives kfuncs the
ability to try and acquire a reference on that kptr without requiring
the BPF prog to do something like this:
struct kptr_type *in_map, *new = NULL;
in_map = bpf_kptr_xchg(&map->value, NULL);
if (in_map) {
new = bpf_kptr_type_acquire(in_map);
in_map = bpf_kptr_xchg(&map->value, in_map);
if (in_map)
bpf_kptr_type_release(in_map);
}
That's clearly a pretty ugly (and racy) UX, and if using KF_KPTR_GET is
the only alternative, it's better than nothing. However, the problem
with any KF_KPTR_GET kfunc lies in the fact that it always requires some
kind of synchronization in order to safely do an opportunistic acquire
of the kptr in the map. This is because a BPF program running on another
CPU could do a bpf_kptr_xchg() on that map value, and free the kptr
after it's been read by the KF_KPTR_GET kfunc. For example, the
now-removed bpf_task_kptr_get() kfunc did the following:
struct task_struct *bpf_task_kptr_get(struct task_struct **pp)
{
struct task_struct *p;
rcu_read_lock();
p = READ_ONCE(*pp);
/* If p is non-NULL, it could still be freed by another CPU,
* so we have to do an opportunistic refcount_inc_not_zero()
* and return NULL if the task will be freed after the
* current RCU read region.
*/
|f (p && !refcount_inc_not_zero(&p->rcu_users))
p = NULL;
rcu_read_unlock();
return p;
}
In other words, the kfunc uses RCU to ensure that the task remains valid
after it's been peeked from the map. However, this is completely
redundant with just defining a KF_RCU kfunc that itself does a
refcount_inc_not_zero(), which is exactly what bpf_task_acquire() now
does.
So, the question of whether KF_KPTR_GET is useful is actually, "Are
there any synchronization mechanisms / safety flags that are required by
certain kptrs, but which are not provided by the verifier to kfuncs?"
The answer to that question today is "No", because every kptr we
currently care about is RCU protected.
Even if the answer ever became "yes", the proper way to support that
referenced kptr type would be to add support for whatever
synchronization mechanism it requires in the verifier, rather than
giving kfuncs a flag that says, "Here's a pointer to a referenced kptr
in a map, do whatever you need to do."
With all that said -- so as to allow us to consolidate the kfunc API,
and simplify the verifier a bit, this patch removes KF_KPTR_GET, and all
relevant logic from the verifier.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230416084928.326135-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
All btf_fields in an object are 0-initialized by memset in
bpf_obj_init. This might not be a valid initial state for some field
types, in which case kfuncs that use the type will properly initialize
their input if it's been 0-initialized. Some BPF graph collection types
and kfuncs do this: bpf_list_{head,node} and bpf_rb_node.
An earlier patch in this series added the bpf_refcount field, for which
the 0 state indicates that the refcounted object should be free'd.
bpf_obj_init treats this field specially, setting refcount to 1 instead
of relying on scattered "refcount is 0? Must have just been initialized,
let's set to 1" logic in kfuncs.
This patch extends this treatment to list and rbtree field types,
allowing most scattered initialization logic in kfuncs to be removed.
Note that bpf_{list_head,rb_root} may be inside a BPF map, in which case
they'll be 0-initialized without passing through the newly-added logic,
so scattered initialization logic must remain for these collection root
types.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-9-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch modifies bpf_rbtree_remove to account for possible failure
due to the input rb_node already not being in any collection.
The function can now return NULL, and does when the aforementioned
scenario occurs. As before, on successful removal an owning reference to
the removed node is returned.
Adding KF_RET_NULL to bpf_rbtree_remove's kfunc flags - now KF_RET_NULL |
KF_ACQUIRE - provides the desired verifier semantics:
* retval must be checked for NULL before use
* if NULL, retval's ref_obj_id is released
* retval is a "maybe acquired" owning ref, not a non-owning ref,
so it will live past end of critical section (bpf_spin_unlock), and
thus can be checked for NULL after the end of the CS
BPF programs must add checks
============================
This does change bpf_rbtree_remove's verifier behavior. BPF program
writers will need to add NULL checks to their programs, but the
resulting UX looks natural:
bpf_spin_lock(&glock);
n = bpf_rbtree_first(&ghead);
if (!n) { /* ... */}
res = bpf_rbtree_remove(&ghead, &n->node);
bpf_spin_unlock(&glock);
if (!res) /* Newly-added check after this patch */
return 1;
n = container_of(res, /* ... */);
/* Do something else with n */
bpf_obj_drop(n);
return 0;
The "if (!res)" check above is the only addition necessary for the above
program to pass verification after this patch.
bpf_rbtree_remove no longer clobbers non-owning refs
====================================================
An issue arises when bpf_rbtree_remove fails, though. Consider this
example:
struct node_data {
long key;
struct bpf_list_node l;
struct bpf_rb_node r;
struct bpf_refcount ref;
};
long failed_sum;
void bpf_prog()
{
struct node_data *n = bpf_obj_new(/* ... */);
struct bpf_rb_node *res;
n->key = 10;
bpf_spin_lock(&glock);
bpf_list_push_back(&some_list, &n->l); /* n is now a non-owning ref */
res = bpf_rbtree_remove(&some_tree, &n->r, /* ... */);
if (!res)
failed_sum += n->key; /* not possible */
bpf_spin_unlock(&glock);
/* if (res) { do something useful and drop } ... */
}
The bpf_rbtree_remove in this example will always fail. Similarly to
bpf_spin_unlock, bpf_rbtree_remove is a non-owning reference
invalidation point. The verifier clobbers all non-owning refs after a
bpf_rbtree_remove call, so the "failed_sum += n->key" line will fail
verification, and in fact there's no good way to get information about
the node which failed to add after the invalidation. This patch removes
non-owning reference invalidation from bpf_rbtree_remove to allow the
above usecase to pass verification. The logic for why this is now
possible is as follows:
Before this series, bpf_rbtree_add couldn't fail and thus assumed that
its input, a non-owning reference, was in the tree. But it's easy to
construct an example where two non-owning references pointing to the same
underlying memory are acquired and passed to rbtree_remove one after
another (see rbtree_api_release_aliasing in
selftests/bpf/progs/rbtree_fail.c).
So it was necessary to clobber non-owning refs to prevent this
case and, more generally, to enforce "non-owning ref is definitely
in some collection" invariant. This series removes that invariant and
the failure / runtime checking added in this patch provide a clean way
to deal with the aliasing issue - just fail to remove.
Because the aliasing issue prevented by clobbering non-owning refs is no
longer an issue, this patch removes the invalidate_non_owning_refs
call from verifier handling of bpf_rbtree_remove. Note that
bpf_spin_unlock - the other caller of invalidate_non_owning_refs -
clobbers non-owning refs for a different reason, so its clobbering
behavior remains unchanged.
No BPF program changes are necessary for programs to remain valid as a
result of this clobbering change. A valid program before this patch
passed verification with its non-owning refs having shorter (or equal)
lifetimes due to more aggressive clobbering.
Also, update existing tests to check bpf_rbtree_remove retval for NULL
where necessary, and move rbtree_api_release_aliasing from
progs/rbtree_fail.c to progs/rbtree.c since it's now expected to pass
verification.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-8-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Consider this code snippet:
struct node {
long key;
bpf_list_node l;
bpf_rb_node r;
bpf_refcount ref;
}
int some_bpf_prog(void *ctx)
{
struct node *n = bpf_obj_new(/*...*/), *m;
bpf_spin_lock(&glock);
bpf_rbtree_add(&some_tree, &n->r, /* ... */);
m = bpf_refcount_acquire(n);
bpf_rbtree_add(&other_tree, &m->r, /* ... */);
bpf_spin_unlock(&glock);
/* ... */
}
After bpf_refcount_acquire, n and m point to the same underlying memory,
and that node's bpf_rb_node field is being used by the some_tree insert,
so overwriting it as a result of the second insert is an error. In order
to properly support refcounted nodes, the rbtree and list insert
functions must be allowed to fail. This patch adds such support.
The kfuncs bpf_rbtree_add, bpf_list_push_{front,back} are modified to
return an int indicating success/failure, with 0 -> success, nonzero ->
failure.
bpf_obj_drop on failure
=======================
Currently the only reason an insert can fail is the example above: the
bpf_{list,rb}_node is already in use. When such a failure occurs, the
insert kfuncs will bpf_obj_drop the input node. This allows the insert
operations to logically fail without changing their verifier owning ref
behavior, namely the unconditional release_reference of the input
owning ref.
With insert that always succeeds, ownership of the node is always passed
to the collection, since the node always ends up in the collection.
With a possibly-failed insert w/ bpf_obj_drop, ownership of the node
is always passed either to the collection (success), or to bpf_obj_drop
(failure). Regardless, it's correct to continue unconditionally
releasing the input owning ref, as something is always taking ownership
from the calling program on insert.
Keeping owning ref behavior unchanged results in a nice default UX for
insert functions that can fail. If the program's reaction to a failed
insert is "fine, just get rid of this owning ref for me and let me go
on with my business", then there's no reason to check for failure since
that's default behavior. e.g.:
long important_failures = 0;
int some_bpf_prog(void *ctx)
{
struct node *n, *m, *o; /* all bpf_obj_new'd */
bpf_spin_lock(&glock);
bpf_rbtree_add(&some_tree, &n->node, /* ... */);
bpf_rbtree_add(&some_tree, &m->node, /* ... */);
if (bpf_rbtree_add(&some_tree, &o->node, /* ... */)) {
important_failures++;
}
bpf_spin_unlock(&glock);
}
If we instead chose to pass ownership back to the program on failed
insert - by returning NULL on success or an owning ref on failure -
programs would always have to do something with the returned ref on
failure. The most likely action is probably "I'll just get rid of this
owning ref and go about my business", which ideally would look like:
if (n = bpf_rbtree_add(&some_tree, &n->node, /* ... */))
bpf_obj_drop(n);
But bpf_obj_drop isn't allowed in a critical section and inserts must
occur within one, so in reality error handling would become a
hard-to-parse mess.
For refcounted nodes, we can replicate the "pass ownership back to
program on failure" logic with this patch's semantics, albeit in an ugly
way:
struct node *n = bpf_obj_new(/* ... */), *m;
bpf_spin_lock(&glock);
m = bpf_refcount_acquire(n);
if (bpf_rbtree_add(&some_tree, &n->node, /* ... */)) {
/* Do something with m */
}
bpf_spin_unlock(&glock);
bpf_obj_drop(m);
bpf_refcount_acquire is used to simulate "return owning ref on failure".
This should be an uncommon occurrence, though.
Addition of two verifier-fixup'd args to collection inserts
===========================================================
The actual bpf_obj_drop kfunc is
bpf_obj_drop_impl(void *, struct btf_struct_meta *), with bpf_obj_drop
macro populating the second arg with 0 and the verifier later filling in
the arg during insn fixup.
Because bpf_rbtree_add and bpf_list_push_{front,back} now might do
bpf_obj_drop, these kfuncs need a btf_struct_meta parameter that can be
passed to bpf_obj_drop_impl.
Similarly, because the 'node' param to those insert functions is the
bpf_{list,rb}_node within the node type, and bpf_obj_drop expects a
pointer to the beginning of the node, the insert functions need to be
able to find the beginning of the node struct. A second
verifier-populated param is necessary: the offset of {list,rb}_node within the
node type.
These two new params allow the insert kfuncs to correctly call
__bpf_obj_drop_impl:
beginning_of_node = bpf_rb_node_ptr - offset
if (already_inserted)
__bpf_obj_drop_impl(beginning_of_node, btf_struct_meta->record);
Similarly to other kfuncs with "hidden" verifier-populated params, the
insert functions are renamed with _impl prefix and a macro is provided
for common usage. For example, bpf_rbtree_add kfunc is now
bpf_rbtree_add_impl and bpf_rbtree_add is now a macro which sets
"hidden" args to 0.
Due to the two new args BPF progs will need to be recompiled to work
with the new _impl kfuncs.
This patch also rewrites the "hidden argument" explanation to more
directly say why the BPF program writer doesn't need to populate the
arguments with anything meaningful.
How does this new logic affect non-owning references?
=====================================================
Currently, non-owning refs are valid until the end of the critical
section in which they're created. We can make this guarantee because, if
a non-owning ref exists, the referent was added to some collection. The
collection will drop() its nodes when it goes away, but it can't go away
while our program is accessing it, so that's not a problem. If the
referent is removed from the collection in the same CS that it was added
in, it can't be bpf_obj_drop'd until after CS end. Those are the only
two ways to free the referent's memory and neither can happen until
after the non-owning ref's lifetime ends.
On first glance, having these collection insert functions potentially
bpf_obj_drop their input seems like it breaks the "can't be
bpf_obj_drop'd until after CS end" line of reasoning. But we care about
the memory not being _freed_ until end of CS end, and a previous patch
in the series modified bpf_obj_drop such that it doesn't free refcounted
nodes until refcount == 0. So the statement can be more accurately
rewritten as "can't be free'd until after CS end".
We can prove that this rewritten statement holds for any non-owning
reference produced by collection insert functions:
* If the input to the insert function is _not_ refcounted
* We have an owning reference to the input, and can conclude it isn't
in any collection
* Inserting a node in a collection turns owning refs into
non-owning, and since our input type isn't refcounted, there's no
way to obtain additional owning refs to the same underlying
memory
* Because our node isn't in any collection, the insert operation
cannot fail, so bpf_obj_drop will not execute
* If bpf_obj_drop is guaranteed not to execute, there's no risk of
memory being free'd
* Otherwise, the input to the insert function is refcounted
* If the insert operation fails due to the node's list_head or rb_root
already being in some collection, there was some previous successful
insert which passed refcount to the collection
* We have an owning reference to the input, it must have been
acquired via bpf_refcount_acquire, which bumped the refcount
* refcount must be >= 2 since there's a valid owning reference and the
node is already in a collection
* Insert triggering bpf_obj_drop will decr refcount to >= 1, never
resulting in a free
So although we may do bpf_obj_drop during the critical section, this
will never result in memory being free'd, and no changes to non-owning
ref logic are needed in this patch.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-6-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, BPF programs can interact with the lifetime of refcounted
local kptrs in the following ways:
bpf_obj_new - Initialize refcount to 1 as part of new object creation
bpf_obj_drop - Decrement refcount and free object if it's 0
collection add - Pass ownership to the collection. No change to
refcount but collection is responsible for
bpf_obj_dropping it
In order to be able to add a refcounted local kptr to multiple
collections we need to be able to increment the refcount and acquire a
new owning reference. This patch adds a kfunc, bpf_refcount_acquire,
implementing such an operation.
bpf_refcount_acquire takes a refcounted local kptr and returns a new
owning reference to the same underlying memory as the input. The input
can be either owning or non-owning. To reinforce why this is safe,
consider the following code snippets:
struct node *n = bpf_obj_new(typeof(*n)); // A
struct node *m = bpf_refcount_acquire(n); // B
In the above snippet, n will be alive with refcount=1 after (A), and
since nothing changes that state before (B), it's obviously safe. If
n is instead added to some rbtree, we can still safely refcount_acquire
it:
struct node *n = bpf_obj_new(typeof(*n));
struct node *m;
bpf_spin_lock(&glock);
bpf_rbtree_add(&groot, &n->node, less); // A
m = bpf_refcount_acquire(n); // B
bpf_spin_unlock(&glock);
In the above snippet, after (A) n is a non-owning reference, and after
(B) m is an owning reference pointing to the same memory as n. Although
n has no ownership of that memory's lifetime, it's guaranteed to be
alive until the end of the critical section, and n would be clobbered if
we were past the end of the critical section, so it's safe to bump
refcount.
Implementation details:
* From verifier's perspective, bpf_refcount_acquire handling is similar
to bpf_obj_new and bpf_obj_drop. Like the former, it returns a new
owning reference matching input type, although like the latter, type
can be inferred from concrete kptr input. Verifier changes in
{check,fixup}_kfunc_call and check_kfunc_args are largely copied from
aforementioned functions' verifier changes.
* An exception to the above is the new KF_ARG_PTR_TO_REFCOUNTED_KPTR
arg, indicated by new "__refcounted_kptr" kfunc arg suffix. This is
necessary in order to handle both owning and non-owning input without
adding special-casing to "__alloc" arg handling. Also a convenient
place to confirm that input type has bpf_refcount field.
* The implemented kfunc is actually bpf_refcount_acquire_impl, with
'hidden' second arg that the verifier sets to the type's struct_meta
in fixup_kfunc_call.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-5-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A local kptr is considered 'refcounted' when it is of a type that has a
bpf_refcount field. When such a kptr is created, its refcount should be
initialized to 1; when destroyed, the object should be free'd only if a
refcount decr results in 0 refcount.
Existing logic always frees the underlying memory when destroying a
local kptr, and 0-initializes all btf_record fields. This patch adds
checks for "is local kptr refcounted?" and new logic for that case in
the appropriate places.
This patch focuses on changing existing semantics and thus conspicuously
does _not_ provide a way for BPF programs in increment refcount. That
follows later in the series.
__bpf_obj_drop_impl is modified to do the right thing when it sees a
refcounted type. Container types for graph nodes (list, tree, stashed in
map) are migrated to use __bpf_obj_drop_impl as a destructor for their
nodes instead of each having custom destruction code in their _free
paths. Now that "drop" isn't a synonym for "free" when the type is
refcounted it makes sense to centralize this logic.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-4-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
