Certain bpf syscall subcommands are available for usage from both
userspace and the kernel. LSM modules or eBPF gatekeeper programs may
need to take a different course of action depending on whether or not
a BPF syscall originated from the kernel or userspace.
Additionally, some of the bpf_attr struct fields contain pointers to
arbitrary memory. Currently the functionality to determine whether or
not a pointer refers to kernel memory or userspace memory is exposed
to the bpf verifier, but that information is missing from various LSM
hooks.
Here we augment the LSM hooks to provide this data, by simply passing
a boolean flag indicating whether or not the call originated in the
kernel, in any hook that contains a bpf_attr struct that corresponds
to a subcommand that may be called from the kernel.
Signed-off-by: Blaise Boscaccy <bboscaccy@linux.microsoft.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20250310221737.821889-2-bboscaccy@linux.microsoft.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Some bpf_cpumask-related kfuncs have kdoc strings that are missing
return values. Add a the missing descriptions for the return values.
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Emil Tsalapatis (Meta) <emil@etsalapatis.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250309230427.26603-4-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a helper kfunc that sets the bitmap of a bpf_cpumask from BPF memory.
Signed-off-by: Emil Tsalapatis (Meta) <emil@etsalapatis.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250309230427.26603-2-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
may_goto instruction does not use any registers,
but in compute_insn_live_regs() it was treated as a regular
conditional jump of kind BPF_K with r0 as source register.
Thus unnecessarily marking r0 as used.
Fixes: 14c8552db6 ("bpf: simple DFA-based live registers analysis")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250305085436.2731464-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Compute may-live registers before each instruction in the program.
The register is live before the instruction I if it is read by I or
some instruction S following I during program execution and is not
overwritten between I and S.
This information would be used in the next patch as a hint in
func_states_equal().
Use a simple algorithm described in [1] to compute this information:
- define the following:
- I.use : a set of all registers read by instruction I;
- I.def : a set of all registers written by instruction I;
- I.in : a set of all registers that may be alive before I execution;
- I.out : a set of all registers that may be alive after I execution;
- I.successors : a set of instructions S that might immediately
follow I for some program execution;
- associate separate empty sets 'I.in' and 'I.out' with each instruction;
- visit each instruction in a postorder and update corresponding
'I.in' and 'I.out' sets as follows:
I.out = U [S.in for S in I.successors]
I.in = (I.out / I.def) U I.use
(where U stands for set union, / stands for set difference)
- repeat the computation while I.{in,out} changes for any instruction.
On implementation side keep things as simple, as possible:
- check_cfg() already marks instructions EXPLORED in post-order,
modify it to save the index of each EXPLORED instruction in a vector;
- represent I.{in,out,use,def} as bitmasks;
- don't split the program into basic blocks and don't maintain the
work queue, instead:
- do fixed-point computation by visiting each instruction;
- maintain a simple 'changed' flag if I.{in,out} for any instruction
change;
Measurements show that even such simplistic implementation does not
add measurable verification time overhead (for selftests, at-least).
Note on check_cfg() ex_insn_beg/ex_done change:
To avoid out of bounds access to env->cfg.insn_postorder array,
it should be guaranteed that instruction transitions to EXPLORED state
only once. Previously this was not the fact for incorrect programs
with direct calls to exception callbacks.
The 'align' selftest needs adjustment to skip computed insn/live
registers printout. Otherwise it matches lines from the live registers
printout.
[1] https://en.wikipedia.org/wiki/Live-variable_analysis
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250304195024.2478889-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor mark_fastcall_pattern_for_call() to extract a utility
function get_call_summary(). For a helper or kfunc call this function
fills the following information: {num_params, is_void, fastcall}.
This function would be used in the next patch in order to get number
of parameters of a helper or kfunc call.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250304195024.2478889-3-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Extract two utility functions:
- One BPF jump instruction uses .imm field to encode jump offset,
while the rest use .off. Encapsulate this detail as jmp_offset()
function.
- Avoid duplicating instruction printing callback definitions by
defining a verbose_insn() function, which disassembles an
instruction into the verifier log while hiding this detail.
These functions will be used in the next patch.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250304195024.2478889-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introduce BPF instructions with load-acquire and store-release
semantics, as discussed in [1]. Define 2 new flags:
#define BPF_LOAD_ACQ 0x100
#define BPF_STORE_REL 0x110
A "load-acquire" is a BPF_STX | BPF_ATOMIC instruction with the 'imm'
field set to BPF_LOAD_ACQ (0x100).
Similarly, a "store-release" is a BPF_STX | BPF_ATOMIC instruction with
the 'imm' field set to BPF_STORE_REL (0x110).
Unlike existing atomic read-modify-write operations that only support
BPF_W (32-bit) and BPF_DW (64-bit) size modifiers, load-acquires and
store-releases also support BPF_B (8-bit) and BPF_H (16-bit). As an
exception, however, 64-bit load-acquires/store-releases are not
supported on 32-bit architectures (to fix a build error reported by the
kernel test robot).
An 8- or 16-bit load-acquire zero-extends the value before writing it to
a 32-bit register, just like ARM64 instruction LDARH and friends.
Similar to existing atomic read-modify-write operations, misaligned
load-acquires/store-releases are not allowed (even if
BPF_F_ANY_ALIGNMENT is set).
As an example, consider the following 64-bit load-acquire BPF
instruction (assuming little-endian):
db 10 00 00 00 01 00 00 r0 = load_acquire((u64 *)(r1 + 0x0))
opcode (0xdb): BPF_ATOMIC | BPF_DW | BPF_STX
imm (0x00000100): BPF_LOAD_ACQ
Similarly, a 16-bit BPF store-release:
cb 21 00 00 10 01 00 00 store_release((u16 *)(r1 + 0x0), w2)
opcode (0xcb): BPF_ATOMIC | BPF_H | BPF_STX
imm (0x00000110): BPF_STORE_REL
In arch/{arm64,s390,x86}/net/bpf_jit_comp.c, have
bpf_jit_supports_insn(..., /*in_arena=*/true) return false for the new
instructions, until the corresponding JIT compiler supports them in
arena.
[1] https://lore.kernel.org/all/20240729183246.4110549-1-yepeilin@google.com/
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Peilin Ye <yepeilin@google.com>
Link: https://lore.kernel.org/r/a217f46f0e445fbd573a1a024be5c6bf1d5fe716.1741049567.git.yepeilin@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Implement support in the verifier for replacing may_goto implementation
from a counter-based approach to one which samples time on the local CPU
to have a bigger loop bound.
We implement it by maintaining 16-bytes per-stack frame, and using 8
bytes for maintaining the count for amortizing time sampling, and 8
bytes for the starting timestamp. To minimize overhead, we need to avoid
spilling and filling of registers around this sequence, so we push this
cost into the time sampling function 'arch_bpf_timed_may_goto'. This is
a JIT-specific wrapper around bpf_check_timed_may_goto which returns us
the count to store into the stack through BPF_REG_AX. All caller-saved
registers (r0-r5) are guaranteed to remain untouched.
The loop can be broken by returning count as 0, otherwise we dispatch
into the function when the count drops to 0, and the runtime chooses to
refresh it (by returning count as BPF_MAX_TIMED_LOOPS) or returning 0
and aborting the loop on next iteration.
Since the check for 0 is done right after loading the count from the
stack, all subsequent cond_break sequences should immediately break as
well, of the same loop or subsequent loops in the program.
We pass in the stack_depth of the count (and thus the timestamp, by
adding 8 to it) to the arch_bpf_timed_may_goto call so that it can be
passed in to bpf_check_timed_may_goto as an argument after r1 is saved,
by adding the offset to r10/fp. This adjustment will be arch specific,
and the next patch will introduce support for x86.
Note that depending on loop complexity, time spent in the loop can be
more than the current limit (250 ms), but imposing an upper bound on
program runtime is an orthogonal problem which will be addressed when
program cancellations are supported.
The current time afforded by cond_break may not be enough for cases
where BPF programs want to implement locking algorithms inline, and use
cond_break as a promise to the verifier that they will eventually
terminate.
Below are some benchmarking numbers on the time taken per-iteration for
an empty loop that counts the number of iterations until cond_break
fires. For comparison, we compare it against bpf_for/bpf_repeat which is
another way to achieve the same number of spins (BPF_MAX_LOOPS). The
hardware used for benchmarking was a Sapphire Rapids Intel server with
performance governor enabled, mitigations were enabled.
+-----------------------------+--------------+--------------+------------------+
| Loop type | Iterations | Time (ms) | Time/iter (ns) |
+-----------------------------|--------------+--------------+------------------+
| may_goto | 8388608 | 3 | 0.36 |
| timed_may_goto (count=65535)| 589674932 | 250 | 0.42 |
| bpf_for | 8388608 | 10 | 1.19 |
+-----------------------------+--------------+--------------+------------------+
This gives a good approximation at low overhead while staying close to
the current implementation.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250304003239.2390751-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Extract BPF_LDX and most non-ATOMIC BPF_STX instruction handling logic
in do_check() into helper functions to be used later. While we are
here, make that comment about "reserved fields" more specific.
Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Peilin Ye <yepeilin@google.com>
Link: https://lore.kernel.org/r/8b39c94eac2bb7389ff12392ca666f939124ec4f.1740978603.git.yepeilin@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, check_atomic() only handles atomic read-modify-write (RMW)
instructions. Since we are planning to introduce other types of atomic
instructions (i.e., atomic load/store), extract the existing RMW
handling logic into its own function named check_atomic_rmw().
Remove the @insn_idx parameter as it is not really necessary. Use
'env->insn_idx' instead, as in other places in verifier.c.
Signed-off-by: Peilin Ye <yepeilin@google.com>
Link: https://lore.kernel.org/r/6323ac8e73a10a1c8ee547c77ed68cf8eb6b90e1.1740978603.git.yepeilin@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_sk_storage_clone() is the only caller of bpf_map_inc_not_zero()
and is holding rcu_read_lock().
map_idr_lock does not add any protection, just remove the cost
for passive TCP flows.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Kui-Feng Lee <kuifeng@meta.com>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://lore.kernel.org/r/20250301191315.1532629-1-edumazet@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The verifier currently does not permit global subprog calls when a lock
is held, preemption is disabled, or when IRQs are disabled. This is
because we don't know whether the global subprog calls sleepable
functions or not.
In case of locks, there's an additional reason: functions called by the
global subprog may hold additional locks etc. The verifier won't know
while verifying the global subprog whether it was called in context
where a spin lock is already held by the program.
Perform summarization of the sleepable nature of a global subprog just
like changes_pkt_data and then allow calls to global subprogs for
non-sleepable ones from atomic context.
While making this change, I noticed that RCU read sections had no
protection against sleepable global subprog calls, include it in the
checks and fix this while we're at it.
Care needs to be taken to not allow global subprog calls when regular
bpf_spin_lock is held. When resilient spin locks is held, we want to
potentially have this check relaxed, but not for now.
Also make sure extensions freplacing global functions cannot do so
in case the target is non-sleepable, but the extension is. The other
combination is ok.
Tests are included in the next patch to handle all special conditions.
Fixes: 9bb00b2895 ("bpf: Add kfunc bpf_rcu_read_lock/unlock()")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250301151846.1552362-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently for bpf progs in a cgroup hierarchy, the effective prog array
is computed from bottom cgroup to upper cgroups (post-ordering). For
example, the following cgroup hierarchy
root cgroup: p1, p2
subcgroup: p3, p4
have BPF_F_ALLOW_MULTI for both cgroup levels.
The effective cgroup array ordering looks like
p3 p4 p1 p2
and at run time, progs will execute based on that order.
But in some cases, it is desirable to have root prog executes earlier than
children progs (pre-ordering). For example,
- prog p1 intends to collect original pkt dest addresses.
- prog p3 will modify original pkt dest addresses to a proxy address for
security reason.
The end result is that prog p1 gets proxy address which is not what it
wants. Putting p1 to every child cgroup is not desirable either as it
will duplicate itself in many child cgroups. And this is exactly a use case
we are encountering in Meta.
To fix this issue, let us introduce a flag BPF_F_PREORDER. If the flag
is specified at attachment time, the prog has higher priority and the
ordering with that flag will be from top to bottom (pre-ordering).
For example, in the above example,
root cgroup: p1, p2
subcgroup: p3, p4
Let us say p2 and p4 are marked with BPF_F_PREORDER. The final
effective array ordering will be
p2 p4 p3 p1
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250224230116.283071-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introducing bpf_dynptr_copy kfunc allowing copying data from one dynptr to
another. This functionality is useful in scenarios such as capturing XDP
data to a ring buffer.
The implementation consists of 4 branches:
* A fast branch for contiguous buffer capacity in both source and
destination dynptrs
* 3 branches utilizing __bpf_dynptr_read and __bpf_dynptr_write to copy
data to/from non-contiguous buffer
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250226183201.332713-3-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move the more esoteric helpers for netdev instance lock to
a dedicated header. This avoids growing netdevice.h to infinity
and makes rebuilding the kernel much faster (after touching
the header with the helpers).
The main netdev_lock() / netdev_unlock() functions are used
in static inlines in netdevice.h and will probably be used
most commonly, so keep them in netdevice.h.
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250307183006.2312761-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cover the paths that come via bpf system call and XSK bind.
Cc: Saeed Mahameed <saeed@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250305163732.2766420-10-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Due to this recent commit in the x86 tree:
9d7de2aa8b ("Use relative percpu offsets")
percpu addresses went from positive offsets from the GSBASE to negative
kernel virtual addresses. The BPF verifier has an optimization for
x86-64 that loads the address of cpu_number into a register, but was only
doing a 32-bit load which truncates negative addresses.
Change it to a 64-bit load so that the address is properly sign-extended.
Fixes: 9d7de2aa8b ("Use relative percpu offsets")
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250227195302.1667654-1-brgerst@gmail.com
Some filesystems, such as NFS, cifs, ceph, and fuse, do not have
complete control of sequencing on the actual filesystem (e.g. on a
different server) and may find that the inode created for a mkdir
request already exists in the icache and dcache by the time the mkdir
request returns. For example, if the filesystem is mounted twice the
directory could be visible on the other mount before it is on the
original mount, and a pair of name_to_handle_at(), open_by_handle_at()
calls could instantiate the directory inode with an IS_ROOT() dentry
before the first mkdir returns.
This means that the dentry passed to ->mkdir() may not be the one that
is associated with the inode after the ->mkdir() completes. Some
callers need to interact with the inode after the ->mkdir completes and
they currently need to perform a lookup in the (rare) case that the
dentry is no longer hashed.
This lookup-after-mkdir requires that the directory remains locked to
avoid races. Planned future patches to lock the dentry rather than the
directory will mean that this lookup cannot be performed atomically with
the mkdir.
To remove this barrier, this patch changes ->mkdir to return the
resulting dentry if it is different from the one passed in.
Possible returns are:
NULL - the directory was created and no other dentry was used
ERR_PTR() - an error occurred
non-NULL - this other dentry was spliced in
This patch only changes file-systems to return "ERR_PTR(err)" instead of
"err" or equivalent transformations. Subsequent patches will make
further changes to some file-systems to return a correct dentry.
Not all filesystems reliably result in a positive hashed dentry:
- NFS, cifs, hostfs will sometimes need to perform a lookup of
the name to get inode information. Races could result in this
returning something different. Note that this lookup is
non-atomic which is what we are trying to avoid. Placing the
lookup in filesystem code means it only happens when the filesystem
has no other option.
- kernfs and tracefs leave the dentry negative and the ->revalidate
operation ensures that lookup will be called to correctly populate
the dentry. This could be fixed but I don't think it is important
to any of the users of vfs_mkdir() which look at the dentry.
The recommendation to use
d_drop();d_splice_alias()
is ugly but fits with current practice. A planned future patch will
change this.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250227013949.536172-2-neilb@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
Use try_alloc_pages() and free_pages_nolock() for BPF needs
when context doesn't allow using normal alloc_pages.
This is a prerequisite for further work.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20250222024427.30294-7-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Now that cpumap uses GRO, which drops unused skb heads to the NAPI
cache, use napi_skb_cache_get_bulk() to try to reuse cached entries
and lower MM layer pressure. Always disable the BH before checking and
running the cpumap-pinned XDP prog and don't re-enable it in between
that and allocating an skb bulk, as we can access the NAPI caches only
from the BH context.
The better GRO aggregates packets, the less new skbs will be allocated.
If an aggregated skb contains 16 frags, this means 15 skbs were returned
to the cache, so next 15 skbs will be built without allocating anything.
The same trafficgen UDP GRO test now shows:
GRO off GRO on
threaded GRO 2.3 4 Mpps
thr bulk GRO 2.4 4.7 Mpps
diff +4 +17 %
Comparing to the baseline cpumap:
baseline 2.7 N/A Mpps
thr bulk GRO 2.4 4.7 Mpps
diff -11 +74 %
Tested-by: Daniel Xu <dxu@dxuuu.xyz>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
cpumap still uses linked lists to store a list of skbs to pass to the
stack. Now that we don't use listified Rx in favor of
napi_gro_receive(), linked list is now an unneeded overhead.
Inside the polling loop, we already have an array of skbs. Let's reuse
it for skbs passed to cpumap (generic XDP) and keep there in case of
XDP_PASS when a program is installed to the map itself. Don't list
regular xdp_frames after converting them to skbs as well; store them
in the mentioned array (but *before* generic skbs as the latters have
lower priority) and call gro_receive_skb() for each array element after
they're done.
Tested-by: Daniel Xu <dxu@dxuuu.xyz>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
cpumap has its own BH context based on kthread. It has a sane batch
size of 8 frames per one cycle.
GRO can be used here on its own. Adjust cpumap calls to the upper stack
to use GRO API instead of netif_receive_skb_list() which processes skbs
by batches, but doesn't involve GRO layer at all.
In plenty of tests, GRO performs better than listed receiving even
given that it has to calculate full frame checksums on the CPU.
As GRO passes the skbs to the upper stack in the batches of
@gro_normal_batch, i.e. 8 by default, and skb->dev points to the
device where the frame comes from, it is enough to disable GRO
netdev feature on it to completely restore the original behaviour:
untouched frames will be being bulked and passed to the upper stack
by 8, as it was with netif_receive_skb_list().
Tested-by: Daniel Xu <dxu@dxuuu.xyz>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Test gen_prologue and gen_epilogue that generate kfuncs that have not
been seen in the main program.
The main bpf program and return value checks are identical to
pro_epilogue.c introduced in commit 47e69431b5 ("selftests/bpf: Test
gen_prologue and gen_epilogue"). However, now when bpf_testmod_st_ops
detects a program name with prefix "test_kfunc_", it generates slightly
different prologue and epilogue: They still add 1000 to args->a in
prologue, add 10000 to args->a and set r0 to 2 * args->a in epilogue,
but involve kfuncs.
At high level, the alternative version of prologue and epilogue look
like this:
cgrp = bpf_cgroup_from_id(0);
if (cgrp)
bpf_cgroup_release(cgrp);
else
/* Perform what original bpf_testmod_st_ops prologue or
* epilogue does
*/
Since 0 is never a valid cgroup id, the original prologue or epilogue
logic will be performed. As a result, the __retval check should expect
the exact same return value.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250225233545.285481-2-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, add_kfunc_call() is only invoked once before the main
verification loop. Therefore, the verifier could not find the
bpf_kfunc_btf_tab of a new kfunc call which is not seen in user defined
struct_ops operators but introduced in gen_prologue or gen_epilogue
during do_misc_fixup(). Fix this by searching kfuncs in the patching
instruction buffer and add them to prog->aux->kfunc_tab.
Signed-off-by: Amery Hung <amery.hung@bytedance.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250225233545.285481-1-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Vlad Poenaru reported the following kmemleak issue:
unreferenced object 0x606fd7c44ac8 (size 32):
backtrace (crc 0):
pcpu_alloc_noprof+0x730/0xeb0
bpf_map_alloc_percpu+0x69/0xc0
prealloc_init+0x9d/0x1b0
htab_map_alloc+0x363/0x510
map_create+0x215/0x3a0
__sys_bpf+0x16b/0x3e0
__x64_sys_bpf+0x18/0x20
do_syscall_64+0x7b/0x150
entry_SYSCALL_64_after_hwframe+0x4b/0x53
Further investigation shows the reason is due to not 8-byte aligned
store of percpu pointer in htab_elem_set_ptr():
*(void __percpu **)(l->key + key_size) = pptr;
Note that the whole htab_elem alignment is 8 (for x86_64). If the key_size
is 4, that means pptr is stored in a location which is 4 byte aligned but
not 8 byte aligned. In mm/kmemleak.c, scan_block() scans the memory based
on 8 byte stride, so it won't detect above pptr, hence reporting the memory
leak.
In htab_map_alloc(), we already have
htab->elem_size = sizeof(struct htab_elem) +
round_up(htab->map.key_size, 8);
if (percpu)
htab->elem_size += sizeof(void *);
else
htab->elem_size += round_up(htab->map.value_size, 8);
So storing pptr with 8-byte alignment won't cause any problem and can fix
kmemleak too.
The issue can be reproduced with bpf selftest as well:
1. Enable CONFIG_DEBUG_KMEMLEAK config
2. Add a getchar() before skel destroy in test_hash_map() in prog_tests/for_each.c.
The purpose is to keep map available so kmemleak can be detected.
3. run './test_progs -t for_each/hash_map &' and a kmemleak should be reported.
Reported-by: Vlad Poenaru <thevlad@meta.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250224175514.2207227-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reduce the variable passing madness surrounding check_ctx_access().
Currently, check_mem_access() passes many pointers to local variables to
check_ctx_access(). They are used to initialize "struct
bpf_insn_access_aux info" in check_ctx_access() and then passed to
is_valid_access(). Then, check_ctx_access() takes the data our from
info and write them back the pointers to pass them back. This can be
simpilified by moving info up to check_mem_access().
No functional change.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20250221175644.1822383-1-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reject struct_ops programs with refcounted kptr arguments (arguments
tagged with __ref suffix) that tail call. Once a refcounted kptr is
passed to a struct_ops program from the kernel, it can be freed or
xchged into maps. As there is no guarantee a callee can get the same
valid refcounted kptr in the ctx, we cannot allow such usage.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250220221532.1079331-1-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Fix a soft-lockup in BPF arena_map_free on 64k page size
kernels (Alan Maguire)
- Fix a missing allocation failure check in BPF verifier's
acquire_lock_state (Kumar Kartikeya Dwivedi)
- Fix a NULL-pointer dereference in trace_kfree_skb by adding
kfree_skb to the raw_tp_null_args set (Kuniyuki Iwashima)
- Fix a deadlock when freeing BPF cgroup storage (Abel Wu)
- Fix a syzbot-reported deadlock when holding BPF map's
freeze_mutex (Andrii Nakryiko)
- Fix a use-after-free issue in bpf_test_init when
eth_skb_pkt_type is accessing skb data not containing an
Ethernet header (Shigeru Yoshida)
- Fix skipping non-existing keys in generic_map_lookup_batch
(Yan Zhai)
- Several BPF sockmap fixes to address incorrect TCP copied_seq
calculations, which prevented correct data reads from recv(2)
in user space (Jiayuan Chen)
- Two fixes for BPF map lookup nullness elision (Daniel Xu)
- Fix a NULL-pointer dereference from vmlinux BTF lookup in
bpf_sk_storage_tracing_allowed (Jared Kangas)
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Pull BPF fixes from Daniel Borkmann:
- Fix a soft-lockup in BPF arena_map_free on 64k page size kernels
(Alan Maguire)
- Fix a missing allocation failure check in BPF verifier's
acquire_lock_state (Kumar Kartikeya Dwivedi)
- Fix a NULL-pointer dereference in trace_kfree_skb by adding kfree_skb
to the raw_tp_null_args set (Kuniyuki Iwashima)
- Fix a deadlock when freeing BPF cgroup storage (Abel Wu)
- Fix a syzbot-reported deadlock when holding BPF map's freeze_mutex
(Andrii Nakryiko)
- Fix a use-after-free issue in bpf_test_init when eth_skb_pkt_type is
accessing skb data not containing an Ethernet header (Shigeru
Yoshida)
- Fix skipping non-existing keys in generic_map_lookup_batch (Yan Zhai)
- Several BPF sockmap fixes to address incorrect TCP copied_seq
calculations, which prevented correct data reads from recv(2) in user
space (Jiayuan Chen)
- Two fixes for BPF map lookup nullness elision (Daniel Xu)
- Fix a NULL-pointer dereference from vmlinux BTF lookup in
bpf_sk_storage_tracing_allowed (Jared Kangas)
* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
selftests: bpf: test batch lookup on array of maps with holes
bpf: skip non exist keys in generic_map_lookup_batch
bpf: Handle allocation failure in acquire_lock_state
bpf: verifier: Disambiguate get_constant_map_key() errors
bpf: selftests: Test constant key extraction on irrelevant maps
bpf: verifier: Do not extract constant map keys for irrelevant maps
bpf: Fix softlockup in arena_map_free on 64k page kernel
net: Add rx_skb of kfree_skb to raw_tp_null_args[].
bpf: Fix deadlock when freeing cgroup storage
selftests/bpf: Add strparser test for bpf
selftests/bpf: Fix invalid flag of recv()
bpf: Disable non stream socket for strparser
bpf: Fix wrong copied_seq calculation
strparser: Add read_sock callback
bpf: avoid holding freeze_mutex during mmap operation
bpf: unify VM_WRITE vs VM_MAYWRITE use in BPF map mmaping logic
selftests/bpf: Adjust data size to have ETH_HLEN
bpf, test_run: Fix use-after-free issue in eth_skb_pkt_type()
bpf: Remove unnecessary BTF lookups in bpf_sk_storage_tracing_allowed
Add the bpf_sock_ops_enable_tx_tstamp kfunc to allow BPF programs to
selectively enable TX timestamping on a skb during tcp_sendmsg().
For example, BPF program will limit tracking X numbers of packets
and then will stop there instead of tracing all the sendmsgs of
matched flow all along. It would be helpful for users who cannot
afford to calculate latencies from every sendmsg call probably
due to the performance or storage space consideration.
Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-12-kerneljasonxing@gmail.com
This new kfunc will be able to copy a zero-terminated C strings from
another task's address space. This is similar to `bpf_copy_from_user_str()`
but reads memory of specified task.
Signed-off-by: Jordan Rome <linux@jordanrome.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250213152125.1837400-2-linux@jordanrome.com
Compute env->peak_states as a maximum value of sum of
env->explored_states and env->free_list size.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250215110411.3236773-11-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When fixes from patches 1 and 3 are applied, Patrick Somaru reported
an increase in memory consumption for sched_ext iterator-based
programs hitting 1M instructions limit. For example, 2Gb VMs ran out
of memory while verifying a program. Similar behaviour could be
reproduced on current bpf-next master.
Here is an example of such program:
/* verification completes if given 16G or RAM,
* final env->free_list size is 369,960 entries.
*/
SEC("raw_tp")
__flag(BPF_F_TEST_STATE_FREQ)
__success
int free_list_bomb(const void *ctx)
{
volatile char buf[48] = {};
unsigned i, j;
j = 0;
bpf_for(i, 0, 10) {
/* this forks verifier state:
* - verification of current path continues and
* creates a checkpoint after 'if';
* - verification of forked path hits the
* checkpoint and marks it as loop_entry.
*/
if (bpf_get_prandom_u32())
asm volatile ("");
/* this marks 'j' as precise, thus any checkpoint
* created on current iteration would not be matched
* on the next iteration.
*/
buf[j++] = 42;
j %= ARRAY_SIZE(buf);
}
asm volatile (""::"r"(buf));
return 0;
}
Memory consumption increased due to more states being marked as loop
entries and eventually added to env->free_list.
This commit introduces logic to free states from env->free_list during
verification. A state in env->free_list can be freed if:
- it has no child states;
- it is not used as a loop_entry.
This commit:
- updates bpf_verifier_state->used_as_loop_entry to be a counter
that tracks how many states use this one as a loop entry;
- adds a function maybe_free_verifier_state(), which:
- frees a state if its ->branches and ->used_as_loop_entry counters
are both zero;
- if the state is freed, state->loop_entry->used_as_loop_entry is
decremented, and an attempt is made to free state->loop_entry.
In the example above, this approach reduces the maximum number of
states in the free list from 369,960 to 16,223.
However, this approach has its limitations. If the buf size in the
example above is modified to 64, state caching overflows: the state
for j=0 is evicted from the cache before it can be used to stop
traversal. As a result, states in the free list accumulate because
their branch counters do not reach zero.
The effect of this patch on the selftests looks as follows:
File Program Max free list (A) Max free list (B) Max free list (DIFF)
-------------------------------- ------------------------------------ ----------------- ----------------- --------------------
arena_list.bpf.o arena_list_add 17 3 -14 (-82.35%)
bpf_iter_task_stack.bpf.o dump_task_stack 39 9 -30 (-76.92%)
iters.bpf.o checkpoint_states_deletion 265 89 -176 (-66.42%)
iters.bpf.o clean_live_states 19 0 -19 (-100.00%)
profiler2.bpf.o tracepoint__syscalls__sys_enter_kill 102 1 -101 (-99.02%)
profiler3.bpf.o tracepoint__syscalls__sys_enter_kill 144 0 -144 (-100.00%)
pyperf600_iter.bpf.o on_event 15 0 -15 (-100.00%)
pyperf600_nounroll.bpf.o on_event 1170 1158 -12 (-1.03%)
setget_sockopt.bpf.o skops_sockopt 18 0 -18 (-100.00%)
strobemeta_nounroll1.bpf.o on_event 147 83 -64 (-43.54%)
strobemeta_nounroll2.bpf.o on_event 312 209 -103 (-33.01%)
strobemeta_subprogs.bpf.o on_event 124 86 -38 (-30.65%)
test_cls_redirect_subprogs.bpf.o cls_redirect 15 0 -15 (-100.00%)
timer.bpf.o test1 30 15 -15 (-50.00%)
Measured using "do-not-submit" patches from here:
https://github.com/eddyz87/bpf/tree/get-loop-entry-hungup
Reported-by: Patrick Somaru <patsomaru@meta.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250215110411.3236773-10-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The next patch in the set needs the ability to remove individual
states from env->free_list while only holding a pointer to the state.
Which requires env->free_list to be a doubly linked list.
This patch converts env->free_list and struct bpf_verifier_state_list
to use struct list_head for this purpose. The change to
env->explored_states is collateral.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250215110411.3236773-9-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The patch 9 is simpler if less places modify loop_entry field.
The loop deleted by this patch does not affect correctness, but is a
performance optimization. However, measurements on selftests and
sched_ext programs show that this optimization is unnecessary:
- at most 2 steps are done in get_loop_entry();
- most of the time 0 or 1 steps are done in get_loop_entry().
Measured using "do-not-submit" patches from here:
https://github.com/eddyz87/bpf/tree/get-loop-entry-hungup
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250215110411.3236773-8-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
For a generic loop detection algorithm a graph node can be a loop
header for itself. However, state loop entries are computed for use in
is_state_visited(), where get_loop_entry(state)->branches is checked.
is_state_visited() also checks state->branches, thus the case when
state == state->loop_entry is not interesting for is_state_visited().
This change does not affect correctness, but simplifies
get_loop_entry() a bit and also simplifies change to
update_loop_entry() in patch 9.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250215110411.3236773-7-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tejun Heo reported an infinite loop in get_loop_entry(),
when verifying a sched_ext program layered_dispatch in [1].
After some investigation I'm sure that root cause is fixed by patches
1,3 in this patch-set.
To err on the safe side, this commit modifies get_loop_entry() to
detect infinite loops and abort verification in such cases.
The number of steps get_loop_entry(S) can make while moving along the
bpf_verifier_state->loop_entry chain is bounded by the DFS depth of
state S. This fact is exploited to implement the check.
To avoid dealing with the potential error code returned from
get_loop_entry() in update_loop_entry(), remove the get_loop_entry()
calls there:
- This change does not affect correctness. Loop entries would still be
updated during the backward DFS move in update_branch_counts().
- This change does not affect performance. Measurements show that
get_loop_entry() performs at most 1 step on selftests and at most 2
steps on sched_ext programs (1 step in 17 cases, 2 steps in 3
cases, measured using "do-not-submit" patches from [2]).
[1] https://github.com/sched-ext/scx/
commit f0b27038ea10 ("XXX - kernel stall")
[2] https://github.com/eddyz87/bpf/tree/get-loop-entry-hungup
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250215110411.3236773-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The generic_map_lookup_batch currently returns EINTR if it fails with
ENOENT and retries several times on bpf_map_copy_value. The next batch
would start from the same location, presuming it's a transient issue.
This is incorrect if a map can actually have "holes", i.e.
"get_next_key" can return a key that does not point to a valid value. At
least the array of maps type may contain such holes legitly. Right now
these holes show up, generic batch lookup cannot proceed any more. It
will always fail with EINTR errors.
Rather, do not retry in generic_map_lookup_batch. If it finds a non
existing element, skip to the next key. This simple solution comes with
a price that transient errors may not be recovered, and the iteration
might cycle back to the first key under parallel deletion. For example,
Hou Tao <houtao@huaweicloud.com> pointed out a following scenario:
For LPM trie map:
(1) ->map_get_next_key(map, prev_key, key) returns a valid key
(2) bpf_map_copy_value() return -ENOMENT
It means the key must be deleted concurrently.
(3) goto next_key
It swaps the prev_key and key
(4) ->map_get_next_key(map, prev_key, key) again
prev_key points to a non-existing key, for LPM trie it will treat just
like prev_key=NULL case, the returned key will be duplicated.
With the retry logic, the iteration can continue to the key next to the
deleted one. But if we directly skip to the next key, the iteration loop
would restart from the first key for the lpm_trie type.
However, not all races may be recovered. For example, if current key is
deleted after instead of before bpf_map_copy_value, or if the prev_key
also gets deleted, then the loop will still restart from the first key
for lpm_tire anyway. For generic lookup it might be better to stay
simple, i.e. just skip to the next key. To guarantee that the output
keys are not duplicated, it is better to implement map type specific
batch operations, which can properly lock the trie and synchronize with
concurrent mutators.
Fixes: cb4d03ab49 ("bpf: Add generic support for lookup batch op")
Closes: https://lore.kernel.org/bpf/Z6JXtA1M5jAZx8xD@debian.debian/
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/85618439eea75930630685c467ccefeac0942e2b.1739171594.git.yan@cloudflare.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
hrtimer_setup() takes the callback function pointer as argument and
initializes the timer completely.
Replace hrtimer_init() and the open coded initialization of
hrtimer::function with the new setup mechanism.
Patch was created by using Coccinelle.
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/e4be2486f02a8e0ef5aa42624f1708d23e88ad57.1738746821.git.namcao@linutronix.de
Allow a struct_ops program to return a referenced kptr if the struct_ops
operator's return type is a struct pointer. To make sure the returned
pointer continues to be valid in the kernel, several constraints are
required:
1) The type of the pointer must matches the return type
2) The pointer originally comes from the kernel (not locally allocated)
3) The pointer is in its unmodified form
Implementation wise, a referenced kptr first needs to be allowed to _leak_
in check_reference_leak() if it is in the return register. Then, in
check_return_code(), constraints 1-3 are checked. During struct_ops
registration, a check is also added to warn about operators with
non-struct pointer return.
In addition, since the first user, Qdisc_ops::dequeue, allows a NULL
pointer to be returned when there is no skb to be dequeued, we will allow
a scalar value with value equals to NULL to be returned.
In the future when there is a struct_ops user that always expects a valid
pointer to be returned from an operator, we may extend tagging to the
return value. We can tell the verifier to only allow NULL pointer return
if the return value is tagged with MAY_BE_NULL.
Signed-off-by: Amery Hung <amery.hung@bytedance.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250217190640.1748177-5-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Allows struct_ops programs to acqurie referenced kptrs from arguments
by directly reading the argument.
The verifier will acquire a reference for struct_ops a argument tagged
with "__ref" in the stub function in the beginning of the main program.
The user will be able to access the referenced kptr directly by reading
the context as long as it has not been released by the program.
This new mechanism to acquire referenced kptr (compared to the existing
"kfunc with KF_ACQUIRE") is introduced for ergonomic and semantic reasons.
In the first use case, Qdisc_ops, an skb is passed to .enqueue in the
first argument. This mechanism provides a natural way for users to get a
referenced kptr in the .enqueue struct_ops programs and makes sure that a
qdisc will always enqueue or drop the skb.
Signed-off-by: Amery Hung <amery.hung@bytedance.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250217190640.1748177-3-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, ctx_arg_info is read-only in the view of the verifier since
it is shared among programs of the same attach type. Make each program
have their own copy of ctx_arg_info so that we can use it to store
program specific information.
In the next patch where we support acquiring a referenced kptr through a
struct_ops argument tagged with "__ref", ctx_arg_info->ref_obj_id will
be used to store the unique reference object id of the argument. This
avoids creating a requirement in the verifier that "__ref" tagged
arguments must be the first set of references acquired [0].
[0] https://lore.kernel.org/bpf/20241220195619.2022866-2-amery.hung@gmail.com/
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250217190640.1748177-2-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
may_goto uses an additional 8 bytes on the stack, which causes the
interpreters[] array to go out of bounds when calculating index by
stack_size.
1. If a BPF program is rewritten, re-evaluate the stack size. For non-JIT
cases, reject loading directly.
2. For non-JIT cases, calculating interpreters[idx] may still cause
out-of-bounds array access, and just warn about it.
3. For jit_requested cases, the execution of bpf_func also needs to be
warned. So move the definition of function __bpf_prog_ret0_warn out of
the macro definition CONFIG_BPF_JIT_ALWAYS_ON.
Reported-by: syzbot+d2a2c639d03ac200a4f1@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/0000000000000f823606139faa5d@google.com/
Fixes: 011832b97b ("bpf: Introduce may_goto instruction")
Signed-off-by: Jiayuan Chen <mrpre@163.com>
Link: https://lore.kernel.org/r/20250214091823.46042-2-mrpre@163.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add the following kfuncs to set and remove xattrs from BPF programs:
bpf_set_dentry_xattr
bpf_remove_dentry_xattr
bpf_set_dentry_xattr_locked
bpf_remove_dentry_xattr_locked
The _locked version of these kfuncs are called from hooks where
dentry->d_inode is already locked. Instead of requiring the user
to know which version of the kfuncs to use, the verifier will pick
the proper kfunc based on the calling hook.
Signed-off-by: Song Liu <song@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Matt Bobrowski <mattbobrowski@google.com>
Link: https://lore.kernel.org/r/20250130213549.3353349-5-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add bpf_lsm_inode_removexattr and bpf_lsm_inode_post_removexattr to list
sleepable_lsm_hooks. These two hooks are always called from sleepable
context.
Signed-off-by: Song Liu <song@kernel.org>
Reviewed-by: Matt Bobrowski <mattbobrowski@google.com>
Link: https://lore.kernel.org/r/20250130213549.3353349-4-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Some of the tracepoints slipped when we did the first scan, adding them now.
Fixes: 838a10bd2e ("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20250210175913.2893549-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_arena_alloc_pages() and bpf_arena_free_pages() work with the
bpf_arena pointers [1], which is indicated by the __arena macro in the
kernel source code:
#define __arena __attribute__((address_space(1)))
However currently this information is absent from the debug data in
the vmlinux binary. As a consequence, bpf_arena_* kfuncs declarations
in vmlinux.h (produced by bpftool) do not match prototypes expected by
the BPF programs attempting to use these functions.
Introduce a set of kfunc flags to mark relevant types as bpf_arena
pointers. The flags then can be detected by pahole when generating BTF
from vmlinux's DWARF, allowing it to emit corresponding BTF type tags
for the marked kfuncs.
With recently proposed BTF extension [2], these type tags will be
processed by bpftool when dumping vmlinux.h, and corresponding
compiler attributes will be added to the declarations.
[1] https://lwn.net/Articles/961594/
[2] https://lore.kernel.org/bpf/20250130201239.1429648-1-ihor.solodrai@linux.dev/
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20250206003148.2308659-1-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The acquire_lock_state function needs to handle possible NULL values
returned by acquire_reference_state, and return -ENOMEM.
Fixes: 769b0f1c82 ("bpf: Refactor {acquire,release}_reference_state")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250206105435.2159977-24-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor get_constant_map_key() to disambiguate the constant key
value from potential error values. In the case that the key is
negative, it could be confused for an error.
It's not currently an issue, as the verifier seems to track s32 spills
as u32. So even if the program wrongly uses a negative value for an
arraymap key, the verifier just thinks it's an impossibly high value
which gets correctly discarded.
Refactor anyways to make things cleaner and prevent potential future
issues.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/dfe144259ae7cfc98aa63e1b388a14869a10632a.1738689872.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Previously, we were trying to extract constant map keys for all
bpf_map_lookup_elem(), regardless of map type. This is an issue if the
map has a u64 key and the value is very high, as it can be interpreted
as a negative signed value. This in turn is treated as an error value by
check_func_arg() which causes a valid program to be incorrectly
rejected.
Fix by only extracting constant map keys for relevant maps. This fix
works because nullness elision is only allowed for {PERCPU_}ARRAY maps,
and keys for these are within u32 range. See next commit for an example
via selftest.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reported-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/aa868b642b026ff87ba6105ea151bc8693b35932.1738689872.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
On an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y,
arena_htab tests cause a segmentation fault and soft lockup.
The same failure is not observed with 4k pages on aarch64.
It turns out arena_map_free() is calling
apply_to_existing_page_range() with the address returned by
bpf_arena_get_kern_vm_start(). If this address is not page-aligned
the code ends up calling apply_to_pte_range() with that unaligned
address causing soft lockup.
Fix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the
division by 2 in bpf_arena_get_kern_vm_start() returns
a page-aligned value.
Fixes: 317460317a ("bpf: Introduce bpf_arena.")
Reported-by: Colm Harrington <colm.harrington@oracle.com>
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/r/20250205170059.427458-1-alan.maguire@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BTF type tags and decl tags now may have info->kflag set to 1,
changing the semantics of the tag.
Change BTF verification to permit BTF that makes use of this feature:
* remove kflag check in btf_decl_tag_check_meta(), as both values
are valid
* allow kflag to be set for BTF_KIND_TYPE_TAG type in
btf_ref_type_check_meta()
Make sure kind_flag is NOT set when checking for specific BTF tags,
such as "kptr", "user" etc.
Modify a selftest checking for kflag in decl_tag accordingly.
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20250130201239.1429648-6-ihor.solodrai@linux.dev
In commit 1611603537 ("bpf: Create argument information for nullable arguments."),
it introduced a "__nullable" tagging at the argument name of a
stub function. Some background on the commit:
it requires to tag the stub function instead of directly tagging
the "ops" of a struct. This is because the btf func_proto of the "ops"
does not have the argument name and the "__nullable" is tagged at
the argument name.
To find the stub function of a "ops", it currently relies on a naming
convention on the stub function "st_ops__ops_name".
e.g. tcp_congestion_ops__ssthresh. However, the new kernel
sub system implementing bpf_struct_ops have missed this and
have been surprised that the "__nullable" and the to-be-landed
"__ref" tagging was not effective.
One option would be to give a warning whenever the stub function does
not follow the naming convention, regardless if it requires arg tagging
or not.
Instead, this patch uses the kallsyms_lookup approach and removes
the requirement on the naming convention. The st_ops->cfi_stubs has
all the stub function kernel addresses. kallsyms_lookup() is used to
lookup the function name. With the function name, BTF can be used to
find the BTF func_proto. The existing "__nullable" arg name searching
logic will then fall through.
One notable change is,
if it failed in kallsyms_lookup or it failed in looking up the stub
function name from the BTF, the bpf_struct_ops registration will fail.
This is different from the previous behavior that it silently ignored
the "st_ops__ops_name" function not found error.
The "tcp_congestion_ops", "sched_ext_ops", and "hid_bpf_ops" can still be
registered successfully after this patch. There is struct_ops_maybe_null
selftest to cover the "__nullable" tagging.
Other minor changes:
1. Removed the "%s__%s" format from the pr_warn because the naming
convention is removed.
2. The existing bpf_struct_ops_supported() is also moved earlier
because prepare_arg_info needs to use it to decide if the
stub function is NULL before calling the prepare_arg_info.
Cc: Tejun Heo <tj@kernel.org>
Cc: Benjamin Tissoires <bentiss@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20250127222719.2544255-1-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The following commit
bc235cdb42 ("bpf: Prevent deadlock from recursive bpf_task_storage_[get|delete]")
first introduced deadlock prevention for fentry/fexit programs attaching
on bpf_task_storage helpers. That commit also employed the logic in map
free path in its v6 version.
Later bpf_cgrp_storage was first introduced in
c4bcfb38a9 ("bpf: Implement cgroup storage available to non-cgroup-attached bpf progs")
which faces the same issue as bpf_task_storage, instead of its busy
counter, NULL was passed to bpf_local_storage_map_free() which opened
a window to cause deadlock:
<TASK>
(acquiring local_storage->lock)
_raw_spin_lock_irqsave+0x3d/0x50
bpf_local_storage_update+0xd1/0x460
bpf_cgrp_storage_get+0x109/0x130
bpf_prog_a4d4a370ba857314_cgrp_ptr+0x139/0x170
? __bpf_prog_enter_recur+0x16/0x80
bpf_trampoline_6442485186+0x43/0xa4
cgroup_storage_ptr+0x9/0x20
(holding local_storage->lock)
bpf_selem_unlink_storage_nolock.constprop.0+0x135/0x160
bpf_selem_unlink_storage+0x6f/0x110
bpf_local_storage_map_free+0xa2/0x110
bpf_map_free_deferred+0x5b/0x90
process_one_work+0x17c/0x390
worker_thread+0x251/0x360
kthread+0xd2/0x100
ret_from_fork+0x34/0x50
ret_from_fork_asm+0x1a/0x30
</TASK>
Progs:
- A: SEC("fentry/cgroup_storage_ptr")
- cgid (BPF_MAP_TYPE_HASH)
Record the id of the cgroup the current task belonging
to in this hash map, using the address of the cgroup
as the map key.
- cgrpa (BPF_MAP_TYPE_CGRP_STORAGE)
If current task is a kworker, lookup the above hash
map using function parameter @owner as the key to get
its corresponding cgroup id which is then used to get
a trusted pointer to the cgroup through
bpf_cgroup_from_id(). This trusted pointer can then
be passed to bpf_cgrp_storage_get() to finally trigger
the deadlock issue.
- B: SEC("tp_btf/sys_enter")
- cgrpb (BPF_MAP_TYPE_CGRP_STORAGE)
The only purpose of this prog is to fill Prog A's
hash map by calling bpf_cgrp_storage_get() for as
many userspace tasks as possible.
Steps to reproduce:
- Run A;
- while (true) { Run B; Destroy B; }
Fix this issue by passing its busy counter to the free procedure so
it can be properly incremented before storage/smap locking.
Fixes: c4bcfb38a9 ("bpf: Implement cgroup storage available to non-cgroup-attached bpf progs")
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241221061018.37717-1-wuyun.abel@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
All ctl_table declared outside of functions and that remain unmodified after
initialization are const qualified. This prevents unintended modifications to
proc_handler function pointers by placing them in the .rodata section. This is
a continuation of the tree-wide effort started a few releases ago with the
constification of the ctl_table struct arguments in the sysctl API done in
78eb4ea25c ("sysctl: treewide: constify the ctl_table argument of
proc_handlers")
Testing:
Testing was done on 0-day and sysctl selftests in x86_64. The linux-next
branch was not used for such a big change in order to avoid unnecessary merge
conflicts
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Merge tag 'constfy-sysctl-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl
Pull sysctl table constification from Joel Granados:
"All ctl_table declared outside of functions and that remain unmodified
after initialization are const qualified.
This prevents unintended modifications to proc_handler function
pointers by placing them in the .rodata section.
This is a continuation of the tree-wide effort started a few releases
ago with the constification of the ctl_table struct arguments in the
sysctl API done in 78eb4ea25c ("sysctl: treewide: constify the
ctl_table argument of proc_handlers")"
* tag 'constfy-sysctl-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
treewide: const qualify ctl_tables where applicable
We use map->freeze_mutex to prevent races between map_freeze() and
memory mapping BPF map contents with writable permissions. The way we
naively do this means we'll hold freeze_mutex for entire duration of all
the mm and VMA manipulations, which is completely unnecessary. This can
potentially also lead to deadlocks, as reported by syzbot in [0].
So, instead, hold freeze_mutex only during writeability checks, bump
(proactively) "write active" count for the map, unlock the mutex and
proceed with mmap logic. And only if something went wrong during mmap
logic, then undo that "write active" counter increment.
[0] https://lore.kernel.org/bpf/678dcbc9.050a0220.303755.0066.GAE@google.com/
Fixes: fc9702273e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
Reported-by: syzbot+4dc041c686b7c816a71e@syzkaller.appspotmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20250129012246.1515826-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
For all BPF maps we ensure that VM_MAYWRITE is cleared when
memory-mapping BPF map contents as initially read-only VMA. This is
because in some cases BPF verifier relies on the underlying data to not
be modified afterwards by user space, so once something is mapped
read-only, it shouldn't be re-mmap'ed as read-write.
As such, it's not necessary to check VM_MAYWRITE in bpf_map_mmap() and
map->ops->map_mmap() callbacks: VM_WRITE should be consistently set for
read-write mappings, and if VM_WRITE is not set, there is no way for
user space to upgrade read-only mapping to read-write one.
This patch cleans up this VM_WRITE vs VM_MAYWRITE handling within
bpf_map_mmap(), which is an entry point for any BPF map mmap()-ing
logic. We also drop unnecessary sanitization of VM_MAYWRITE in BPF
ringbuf's map_mmap() callback implementation, as it is already performed
by common code in bpf_map_mmap().
Note, though, that in bpf_map_mmap_{open,close}() callbacks we can't
drop VM_MAYWRITE use, because it's possible (and is outside of
subsystem's control) to have initially read-write memory mapping, which
is subsequently dropped to read-only by user space through mprotect().
In such case, from BPF verifier POV it's read-write data throughout the
lifetime of BPF map, and is counted as "active writer".
But its VMAs will start out as VM_WRITE|VM_MAYWRITE, then mprotect() can
change it to just VM_MAYWRITE (and no VM_WRITE), so when its finally
munmap()'ed and bpf_map_mmap_close() is called, vm_flags will be just
VM_MAYWRITE, but we still need to decrement active writer count with
bpf_map_write_active_dec() as it's still considered to be a read-write
mapping by the rest of BPF subsystem.
Similar reasoning applies to bpf_map_mmap_open(), which is called
whenever mmap(), munmap(), and/or mprotect() forces mm subsystem to
split original VMA into multiple discontiguous VMAs.
Memory-mapping handling is a bit tricky, yes.
Cc: Jann Horn <jannh@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20250129012246.1515826-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Here is the big set of driver core and debugfs updates for 6.14-rc1.
It's coming late in the merge cycle as there are a number of merge
conflicts with your tree now, and I wanted to make sure they were
working properly. To resolve them, look in linux-next, and I will send
the "fixup" patch as a response to the pull request.
Included in here is a bunch of driver core, PCI, OF, and platform rust
bindings (all acked by the different subsystem maintainers), hence the
merge conflict with the rust tree, and some driver core api updates to
mark things as const, which will also require some fixups due to new
stuff coming in through other trees in this merge window.
There are also a bunch of debugfs updates from Al, and there is at least
one user that does have a regression with these, but Al is working on
tracking down the fix for it. In my use (and everyone else's linux-next
use), it does not seem like a big issue at the moment.
Here's a short list of the things in here:
- driver core bindings for PCI, platform, OF, and some i/o functions.
We are almost at the "write a real driver in rust" stage now,
depending on what you want to do.
- misc device rust bindings and a sample driver to show how to use
them
- debugfs cleanups in the fs as well as the users of the fs api for
places where drivers got it wrong or were unnecessarily doing things
in complex ways.
- driver core const work, making more of the api take const * for
different parameters to make the rust bindings easier overall.
- other small fixes and updates
All of these have been in linux-next with all of the aforementioned
merge conflicts, and the one debugfs issue, which looks to be resolved
"soon".
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core and debugfs updates from Greg KH:
"Here is the big set of driver core and debugfs updates for 6.14-rc1.
Included in here is a bunch of driver core, PCI, OF, and platform rust
bindings (all acked by the different subsystem maintainers), hence the
merge conflict with the rust tree, and some driver core api updates to
mark things as const, which will also require some fixups due to new
stuff coming in through other trees in this merge window.
There are also a bunch of debugfs updates from Al, and there is at
least one user that does have a regression with these, but Al is
working on tracking down the fix for it. In my use (and everyone
else's linux-next use), it does not seem like a big issue at the
moment.
Here's a short list of the things in here:
- driver core rust bindings for PCI, platform, OF, and some i/o
functions.
We are almost at the "write a real driver in rust" stage now,
depending on what you want to do.
- misc device rust bindings and a sample driver to show how to use
them
- debugfs cleanups in the fs as well as the users of the fs api for
places where drivers got it wrong or were unnecessarily doing
things in complex ways.
- driver core const work, making more of the api take const * for
different parameters to make the rust bindings easier overall.
- other small fixes and updates
All of these have been in linux-next with all of the aforementioned
merge conflicts, and the one debugfs issue, which looks to be resolved
"soon""
* tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (95 commits)
rust: device: Use as_char_ptr() to avoid explicit cast
rust: device: Replace CString with CStr in property_present()
devcoredump: Constify 'struct bin_attribute'
devcoredump: Define 'struct bin_attribute' through macro
rust: device: Add property_present()
saner replacement for debugfs_rename()
orangefs-debugfs: don't mess with ->d_name
octeontx2: don't mess with ->d_parent or ->d_parent->d_name
arm_scmi: don't mess with ->d_parent->d_name
slub: don't mess with ->d_name
sof-client-ipc-flood-test: don't mess with ->d_name
qat: don't mess with ->d_name
xhci: don't mess with ->d_iname
mtu3: don't mess wiht ->d_iname
greybus/camera - stop messing with ->d_iname
mediatek: stop messing with ->d_iname
netdevsim: don't embed file_operations into your structs
b43legacy: make use of debugfs_get_aux()
b43: stop embedding struct file_operations into their objects
carl9170: stop embedding file_operations into their objects
...
Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.
Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25c ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.
Created this by running an spatch followed by a sed command:
Spatch:
virtual patch
@
depends on !(file in "net")
disable optional_qualifier
@
identifier table_name != {
watchdog_hardlockup_sysctl,
iwcm_ctl_table,
ucma_ctl_table,
memory_allocation_profiling_sysctls,
loadpin_sysctl_table
};
@@
+ const
struct ctl_table table_name [] = { ... };
sed:
sed --in-place \
-e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
kernel/utsname_sysctl.c
Reviewed-by: Song Liu <song@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> # for kernel/trace/
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> # SCSI
Reviewed-by: Darrick J. Wong <djwong@kernel.org> # xfs
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Acked-by: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
indivudual patches which are described in their changelogs.
- "Allocate and free frozen pages" from Matthew Wilcox reorganizes the
page allocator so we end up with the ability to allocate and free
zero-refcount pages. So that callers (ie, slab) can avoid a refcount
inc & dec.
- "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to use
large folios other than PMD-sized ones.
- "Fix mm/rodata_test" from Petr Tesarik performs some maintenance and
fixes for this small built-in kernel selftest.
- "mas_anode_descend() related cleanup" from Wei Yang tidies up part of
the mapletree code.
- "mm: fix format issues and param types" from Keren Sun implements a
few minor code cleanups.
- "simplify split calculation" from Wei Yang provides a few fixes and a
test for the mapletree code.
- "mm/vma: make more mmap logic userland testable" from Lorenzo Stoakes
continues the work of moving vma-related code into the (relatively) new
mm/vma.c.
- "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
Hildenbrand cleans up and rationalizes handling of gfp flags in the page
allocator.
- "readahead: Reintroduce fix for improper RA window sizing" from Jan
Kara is a second attempt at fixing a readahead window sizing issue. It
should reduce the amount of unnecessary reading.
- "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
addresses an issue where "huge" amounts of pte pagetables are
accumulated
(https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/).
Qi's series addresses this windup by synchronously freeing PTE memory
within the context of madvise(MADV_DONTNEED).
- "selftest/mm: Remove warnings found by adding compiler flags" from
Muhammad Usama Anjum fixes some build warnings in the selftests code
when optional compiler warnings are enabled.
- "mm: don't use __GFP_HARDWALL when migrating remote pages" from David
Hildenbrand tightens the allocator's observance of __GFP_HARDWALL.
- "pkeys kselftests improvements" from Kevin Brodsky implements various
fixes and cleanups in the MM selftests code, mainly pertaining to the
pkeys tests.
- "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
estimate application working set size.
- "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
provides some cleanups to memcg's hugetlb charging logic.
- "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
removes the global swap cgroup lock. A speedup of 10% for a tmpfs-based
kernel build was demonstrated.
- "zram: split page type read/write handling" from Sergey Senozhatsky
has several fixes and cleaups for zram in the area of zram_write_page().
A watchdog softlockup warning was eliminated.
- "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin Brodsky
cleans up the pagetable destructor implementations. A rare
use-after-free race is fixed.
- "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
simplifies and cleans up the debugging code in the VMA merging logic.
- "Account page tables at all levels" from Kevin Brodsky cleans up and
regularizes the pagetable ctor/dtor handling. This results in
improvements in accounting accuracy.
- "mm/damon: replace most damon_callback usages in sysfs with new core
functions" from SeongJae Park cleans up and generalizes DAMON's sysfs
file interface logic.
- "mm/damon: enable page level properties based monitoring" from
SeongJae Park increases the amount of information which is presented in
response to DAMOS actions.
- "mm/damon: remove DAMON debugfs interface" from SeongJae Park removes
DAMON's long-deprecated debugfs interfaces. Thus the migration to sysfs
is completed.
- "mm/hugetlb: Refactor hugetlb allocation resv accounting" from Peter
Xu cleans up and generalizes the hugetlb reservation accounting.
- "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
removes a never-used feature of the alloc_pages_bulk() interface.
- "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
extends DAMOS filters to support not only exclusion (rejecting), but
also inclusion (allowing) behavior.
- "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
"introduces a new memory descriptor for zswap.zpool that currently
overlaps with struct page for now. This is part of the effort to reduce
the size of struct page and to enable dynamic allocation of memory
descriptors."
- "mm, swap: rework of swap allocator locks" from Kairui Song redoes and
simplifies the swap allocator locking. A speedup of 400% was
demonstrated for one workload. As was a 35% reduction for kernel build
time with swap-on-zram.
- "mm: update mips to use do_mmap(), make mmap_region() internal" from
Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
mmap_region() can be made MM-internal.
- "mm/mglru: performance optimizations" from Yu Zhao fixes a few MGLRU
regressions and otherwise improves MGLRU performance.
- "Docs/mm/damon: add tuning guide and misc updates" from SeongJae Park
updates DAMON documentation.
- "Cleanup for memfd_create()" from Isaac Manjarres does that thing.
- "mm: hugetlb+THP folio and migration cleanups" from David Hildenbrand
provides various cleanups in the areas of hugetlb folios, THP folios and
migration.
- "Uncached buffered IO" from Jens Axboe implements the new
RWF_DONTCACHE flag which provides synchronous dropbehind for pagecache
reading and writing. To permite userspace to address issues with
massive buildup of useless pagecache when reading/writing fast devices.
- "selftests/mm: virtual_address_range: Reduce memory" from Thomas
Weißschuh fixes and optimizes some of the MM selftests.
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Merge tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"The various patchsets are summarized below. Plus of course many
indivudual patches which are described in their changelogs.
- "Allocate and free frozen pages" from Matthew Wilcox reorganizes
the page allocator so we end up with the ability to allocate and
free zero-refcount pages. So that callers (ie, slab) can avoid a
refcount inc & dec
- "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to
use large folios other than PMD-sized ones
- "Fix mm/rodata_test" from Petr Tesarik performs some maintenance
and fixes for this small built-in kernel selftest
- "mas_anode_descend() related cleanup" from Wei Yang tidies up part
of the mapletree code
- "mm: fix format issues and param types" from Keren Sun implements a
few minor code cleanups
- "simplify split calculation" from Wei Yang provides a few fixes and
a test for the mapletree code
- "mm/vma: make more mmap logic userland testable" from Lorenzo
Stoakes continues the work of moving vma-related code into the
(relatively) new mm/vma.c
- "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
Hildenbrand cleans up and rationalizes handling of gfp flags in the
page allocator
- "readahead: Reintroduce fix for improper RA window sizing" from Jan
Kara is a second attempt at fixing a readahead window sizing issue.
It should reduce the amount of unnecessary reading
- "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
addresses an issue where "huge" amounts of pte pagetables are
accumulated:
https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/
Qi's series addresses this windup by synchronously freeing PTE
memory within the context of madvise(MADV_DONTNEED)
- "selftest/mm: Remove warnings found by adding compiler flags" from
Muhammad Usama Anjum fixes some build warnings in the selftests
code when optional compiler warnings are enabled
- "mm: don't use __GFP_HARDWALL when migrating remote pages" from
David Hildenbrand tightens the allocator's observance of
__GFP_HARDWALL
- "pkeys kselftests improvements" from Kevin Brodsky implements
various fixes and cleanups in the MM selftests code, mainly
pertaining to the pkeys tests
- "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
estimate application working set size
- "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
provides some cleanups to memcg's hugetlb charging logic
- "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
removes the global swap cgroup lock. A speedup of 10% for a
tmpfs-based kernel build was demonstrated
- "zram: split page type read/write handling" from Sergey Senozhatsky
has several fixes and cleaups for zram in the area of
zram_write_page(). A watchdog softlockup warning was eliminated
- "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin
Brodsky cleans up the pagetable destructor implementations. A rare
use-after-free race is fixed
- "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
simplifies and cleans up the debugging code in the VMA merging
logic
- "Account page tables at all levels" from Kevin Brodsky cleans up
and regularizes the pagetable ctor/dtor handling. This results in
improvements in accounting accuracy
- "mm/damon: replace most damon_callback usages in sysfs with new
core functions" from SeongJae Park cleans up and generalizes
DAMON's sysfs file interface logic
- "mm/damon: enable page level properties based monitoring" from
SeongJae Park increases the amount of information which is
presented in response to DAMOS actions
- "mm/damon: remove DAMON debugfs interface" from SeongJae Park
removes DAMON's long-deprecated debugfs interfaces. Thus the
migration to sysfs is completed
- "mm/hugetlb: Refactor hugetlb allocation resv accounting" from
Peter Xu cleans up and generalizes the hugetlb reservation
accounting
- "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
removes a never-used feature of the alloc_pages_bulk() interface
- "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
extends DAMOS filters to support not only exclusion (rejecting),
but also inclusion (allowing) behavior
- "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
introduces a new memory descriptor for zswap.zpool that currently
overlaps with struct page for now. This is part of the effort to
reduce the size of struct page and to enable dynamic allocation of
memory descriptors
- "mm, swap: rework of swap allocator locks" from Kairui Song redoes
and simplifies the swap allocator locking. A speedup of 400% was
demonstrated for one workload. As was a 35% reduction for kernel
build time with swap-on-zram
- "mm: update mips to use do_mmap(), make mmap_region() internal"
from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
mmap_region() can be made MM-internal
- "mm/mglru: performance optimizations" from Yu Zhao fixes a few
MGLRU regressions and otherwise improves MGLRU performance
- "Docs/mm/damon: add tuning guide and misc updates" from SeongJae
Park updates DAMON documentation
- "Cleanup for memfd_create()" from Isaac Manjarres does that thing
- "mm: hugetlb+THP folio and migration cleanups" from David
Hildenbrand provides various cleanups in the areas of hugetlb
folios, THP folios and migration
- "Uncached buffered IO" from Jens Axboe implements the new
RWF_DONTCACHE flag which provides synchronous dropbehind for
pagecache reading and writing. To permite userspace to address
issues with massive buildup of useless pagecache when
reading/writing fast devices
- "selftests/mm: virtual_address_range: Reduce memory" from Thomas
Weißschuh fixes and optimizes some of the MM selftests"
* tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
mm/compaction: fix UBSAN shift-out-of-bounds warning
s390/mm: add missing ctor/dtor on page table upgrade
kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags()
tools: add VM_WARN_ON_VMG definition
mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()
seqlock: add missing parameter documentation for raw_seqcount_try_begin()
mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh
mm/page_alloc: remove the incorrect and misleading comment
zram: remove zcomp_stream_put() from write_incompressible_page()
mm: separate move/undo parts from migrate_pages_batch()
mm/kfence: use str_write_read() helper in get_access_type()
selftests/mm/mkdirty: fix memory leak in test_uffdio_copy()
kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags()
selftests/mm: virtual_address_range: avoid reading from VM_IO mappings
selftests/mm: vm_util: split up /proc/self/smaps parsing
selftests/mm: virtual_address_range: unmap chunks after validation
selftests/mm: virtual_address_range: mmap() without PROT_WRITE
selftests/memfd/memfd_test: fix possible NULL pointer dereference
mm: add FGP_DONTCACHE folio creation flag
mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue
...
The previous commit removed the page_list argument from
alloc_pages_bulk_noprof() along with the alloc_pages_bulk_list() function.
Now that only the *_array() flavour of the API remains, we can do the
following renaming (along with the _noprof() ones):
alloc_pages_bulk_array -> alloc_pages_bulk
alloc_pages_bulk_array_mempolicy -> alloc_pages_bulk_mempolicy
alloc_pages_bulk_array_node -> alloc_pages_bulk_node
Link: https://lkml.kernel.org/r/275a3bbc0be20fbe9002297d60045e67ab3d4ada.1734991165.git.luizcap@redhat.com
Signed-off-by: Luiz Capitulino <luizcap@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Merge tag 'bpf-next-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf updates from Alexei Starovoitov:
"A smaller than usual release cycle.
The main changes are:
- Prepare selftest to run with GCC-BPF backend (Ihor Solodrai)
In addition to LLVM-BPF runs the BPF CI now runs GCC-BPF in compile
only mode. Half of the tests are failing, since support for
btf_decl_tag is still WIP, but this is a great milestone.
- Convert various samples/bpf to selftests/bpf/test_progs format
(Alexis Lothoré and Bastien Curutchet)
- Teach verifier to recognize that array lookup with constant
in-range index will always succeed (Daniel Xu)
- Cleanup migrate disable scope in BPF maps (Hou Tao)
- Fix bpf_timer destroy path in PREEMPT_RT (Hou Tao)
- Always use bpf_mem_alloc in bpf_local_storage in PREEMPT_RT (Martin
KaFai Lau)
- Refactor verifier lock support (Kumar Kartikeya Dwivedi)
This is a prerequisite for upcoming resilient spin lock.
- Remove excessive 'may_goto +0' instructions in the verifier that
LLVM leaves when unrolls the loops (Yonghong Song)
- Remove unhelpful bpf_probe_write_user() warning message (Marco
Elver)
- Add fd_array_cnt attribute for prog_load command (Anton Protopopov)
This is a prerequisite for upcoming support for static_branch"
* tag 'bpf-next-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (125 commits)
selftests/bpf: Add some tests related to 'may_goto 0' insns
bpf: Remove 'may_goto 0' instruction in opt_remove_nops()
bpf: Allow 'may_goto 0' instruction in verifier
selftests/bpf: Add test case for the freeing of bpf_timer
bpf: Cancel the running bpf_timer through kworker for PREEMPT_RT
bpf: Free element after unlock in __htab_map_lookup_and_delete_elem()
bpf: Bail out early in __htab_map_lookup_and_delete_elem()
bpf: Free special fields after unlock in htab_lru_map_delete_node()
tools: Sync if_xdp.h uapi tooling header
libbpf: Work around kernel inconsistently stripping '.llvm.' suffix
bpf: selftests: verifier: Add nullness elision tests
bpf: verifier: Support eliding map lookup nullness
bpf: verifier: Refactor helper access type tracking
bpf: tcp: Mark bpf_load_hdr_opt() arg2 as read-write
bpf: verifier: Add missing newline on verbose() call
selftests/bpf: Add distilled BTF test about marking BTF_IS_EMBEDDED
libbpf: Fix incorrect traversal end type ID when marking BTF_IS_EMBEDDED
libbpf: Fix return zero when elf_begin failed
selftests/bpf: Fix btf leak on new btf alloc failure in btf_distill test
veristat: Load struct_ops programs only once
...
Since 'may_goto 0' insns are actually no-op, let us remove them.
Otherwise, verifier will generate code like
/* r10 - 8 stores the implicit loop count */
r11 = *(u64 *)(r10 -8)
if r11 == 0x0 goto pc+2
r11 -= 1
*(u64 *)(r10 -8) = r11
which is the pure overhead.
The following code patterns (from the previous commit) are also
handled:
may_goto 2
may_goto 1
may_goto 0
With this commit, the above three 'may_goto' insns are all
eliminated.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250118192029.2124584-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit 011832b97b ("bpf: Introduce may_goto instruction") added support
for may_goto insn. The 'may_goto 0' insn is disallowed since the insn is
equivalent to a nop as both branch will go to the next insn.
But it is possible that compiler transformation may generate 'may_goto 0'
insn. Emil Tsalapatis from Meta reported such a case which caused
verification failure. For example, for the following code,
int i, tmp[3];
for (i = 0; i < 3 && can_loop; i++)
tmp[i] = 0;
...
clang 20 may generate code like
may_goto 2;
may_goto 1;
may_goto 0;
r1 = 0; /* tmp[0] = 0; */
r2 = 0; /* tmp[1] = 0; */
r3 = 0; /* tmp[2] = 0; */
Let us permit 'may_goto 0' insn to avoid verification failure for codes
like the above.
Reported-by: Emil Tsalapatis <etsal@meta.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20250118192024.2124059-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
During the update procedure, when overwrite element in a pre-allocated
htab, the freeing of old_element is protected by the bucket lock. The
reason why the bucket lock is necessary is that the old_element has
already been stashed in htab->extra_elems after alloc_htab_elem()
returns. If freeing the old_element after the bucket lock is unlocked,
the stashed element may be reused by concurrent update procedure and the
freeing of old_element will run concurrently with the reuse of the
old_element. However, the invocation of check_and_free_fields() may
acquire a spin-lock which violates the lockdep rule because its caller
has already held a raw-spin-lock (bucket lock). The following warning
will be reported when such race happens:
BUG: scheduling while atomic: test_progs/676/0x00000003
3 locks held by test_progs/676:
#0: ffffffff864b0240 (rcu_read_lock_trace){....}-{0:0}, at: bpf_prog_test_run_syscall+0x2c0/0x830
#1: ffff88810e961188 (&htab->lockdep_key){....}-{2:2}, at: htab_map_update_elem+0x306/0x1500
#2: ffff8881f4eac1b8 (&base->softirq_expiry_lock){....}-{2:2}, at: hrtimer_cancel_wait_running+0xe9/0x1b0
Modules linked in: bpf_testmod(O)
Preemption disabled at:
[<ffffffff817837a3>] htab_map_update_elem+0x293/0x1500
CPU: 0 UID: 0 PID: 676 Comm: test_progs Tainted: G ... 6.12.0+ #11
Tainted: [W]=WARN, [O]=OOT_MODULE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)...
Call Trace:
<TASK>
dump_stack_lvl+0x57/0x70
dump_stack+0x10/0x20
__schedule_bug+0x120/0x170
__schedule+0x300c/0x4800
schedule_rtlock+0x37/0x60
rtlock_slowlock_locked+0x6d9/0x54c0
rt_spin_lock+0x168/0x230
hrtimer_cancel_wait_running+0xe9/0x1b0
hrtimer_cancel+0x24/0x30
bpf_timer_delete_work+0x1d/0x40
bpf_timer_cancel_and_free+0x5e/0x80
bpf_obj_free_fields+0x262/0x4a0
check_and_free_fields+0x1d0/0x280
htab_map_update_elem+0x7fc/0x1500
bpf_prog_9f90bc20768e0cb9_overwrite_cb+0x3f/0x43
bpf_prog_ea601c4649694dbd_overwrite_timer+0x5d/0x7e
bpf_prog_test_run_syscall+0x322/0x830
__sys_bpf+0x135d/0x3ca0
__x64_sys_bpf+0x75/0xb0
x64_sys_call+0x1b5/0xa10
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
...
</TASK>
It seems feasible to break the reuse and refill of per-cpu extra_elems
into two independent parts: reuse the per-cpu extra_elems with bucket
lock being held and refill the old_element as per-cpu extra_elems after
the bucket lock is unlocked. However, it will make the concurrent
overwrite procedures on the same CPU return unexpected -E2BIG error when
the map is full.
Therefore, the patch fixes the lock problem by breaking the cancelling
of bpf_timer into two steps for PREEMPT_RT:
1) use hrtimer_try_to_cancel() and check its return value
2) if the timer is running, use hrtimer_cancel() through a kworker to
cancel it again
Considering that the current implementation of hrtimer_cancel() will try
to acquire a being held softirq_expiry_lock when the current timer is
running, these steps above are reasonable. However, it also has
downside. When the timer is running, the cancelling of the timer is
delayed when releasing the last map uref. The delay is also fixable
(e.g., break the cancelling of bpf timer into two parts: one part in
locked scope, another one in unlocked scope), it can be revised later if
necessary.
It is a bit hard to decide the right fix tag. One reason is that the
problem depends on PREEMPT_RT which is enabled in v6.12. Considering the
softirq_expiry_lock lock exists since v5.4 and bpf_timer is introduced
in v5.15, the bpf_timer commit is used in the fixes tag and an extra
depends-on tag is added to state the dependency on PREEMPT_RT.
Fixes: b00628b1c7 ("bpf: Introduce bpf timers.")
Depends-on: v6.12+ with PREEMPT_RT enabled
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Closes: https://lore.kernel.org/bpf/20241106084527.4gPrMnHt@linutronix.de
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Link: https://lore.kernel.org/r/20250117101816.2101857-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The freeing of special fields in map value may acquire a spin-lock
(e.g., the freeing of bpf_timer), however, the lookup_and_delete_elem
procedure has already held a raw-spin-lock, which violates the lockdep
rule.
The running context of __htab_map_lookup_and_delete_elem() has already
disabled the migration. Therefore, it is OK to invoke free_htab_elem()
after unlocking the bucket lock.
Fix the potential problem by freeing element after unlocking bucket lock
in __htab_map_lookup_and_delete_elem().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250117101816.2101857-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Use goto statement to bail out early when the target element is not
found, instead of using a large else branch to handle the more likely
case. This change doesn't affect functionality and simply make the code
cleaner.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Link: https://lore.kernel.org/r/20250117101816.2101857-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When bpf_timer is used in LRU hash map, calling check_and_free_fields()
in htab_lru_map_delete_node() will invoke bpf_timer_cancel_and_free() to
free the bpf_timer. If the timer is running on other CPUs,
hrtimer_cancel() will invoke hrtimer_cancel_wait_running() to spin on
current CPU to wait for the completion of the hrtimer callback.
Considering that the deletion has already acquired a raw-spin-lock
(bucket lock). To reduce the time holding the bucket lock, move the
invocation of check_and_free_fields() out of bucket lock. However,
because htab_lru_map_delete_node() is invoked with LRU raw spin lock
being held, the freeing of special fields still happens in a locked
scope.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Link: https://lore.kernel.org/r/20250117101816.2101857-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit allows progs to elide a null check on statically known map
lookup keys. In other words, if the verifier can statically prove that
the lookup will be in-bounds, allow the prog to drop the null check.
This is useful for two reasons:
1. Large numbers of nullness checks (especially when they cannot fail)
unnecessarily pushes prog towards BPF_COMPLEXITY_LIMIT_JMP_SEQ.
2. It forms a tighter contract between programmer and verifier.
For (1), bpftrace is starting to make heavier use of percpu scratch
maps. As a result, for user scripts with large number of unrolled loops,
we are starting to hit jump complexity verification errors. These
percpu lookups cannot fail anyways, as we only use static key values.
Eliding nullness probably results in less work for verifier as well.
For (2), percpu scratch maps are often used as a larger stack, as the
currrent stack is limited to 512 bytes. In these situations, it is
desirable for the programmer to express: "this lookup should never fail,
and if it does, it means I messed up the code". By omitting the null
check, the programmer can "ask" the verifier to double check the logic.
Tests also have to be updated in sync with these changes, as the
verifier is more efficient with this change. Notable, iters.c tests had
to be changed to use a map type that still requires null checks, as it's
exercising verifier tracking logic w.r.t iterators.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/68f3ea96ff3809a87e502a11a4bd30177fc5823e.1736886479.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Previously, the verifier was treating all PTR_TO_STACK registers passed
to a helper call as potentially written to by the helper. However, all
calls to check_stack_range_initialized() already have precise access type
information available.
Rather than treat ACCESS_HELPER as a proxy for BPF_WRITE, pass
enum bpf_access_type to check_stack_range_initialized() to more
precisely track helper arguments.
One benefit from this precision is that registers tracked as valid
spills and passed as a read-only helper argument remain tracked after
the call. Rather than being marked STACK_MISC afterwards.
An additional benefit is the verifier logs are also more precise. For
this particular error, users will enjoy a slightly clearer message. See
included selftest updates for examples.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/ff885c0e5859e0cd12077c3148ff0754cad4f7ed.1736886479.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We need the debugfs / driver-core fixes in here as well for testing and
to build on top of.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bpf_selem_free() has the following three callers:
(1) bpf_local_storage_update
It will be invoked through ->map_update_elem syscall or helpers for
storage map. Migration has already been disabled in these running
contexts.
(2) bpf_sk_storage_clone
It has already disabled migration before invoking bpf_selem_free().
(3) bpf_selem_free_list
bpf_selem_free_list() has three callers: bpf_selem_unlink_storage(),
bpf_local_storage_update() and bpf_local_storage_destroy().
The callers of bpf_selem_unlink_storage() includes: storage map
->map_delete_elem syscall, storage map delete helpers and
bpf_local_storage_map_free(). These contexts have already disabled
migration when invoking bpf_selem_unlink() which invokes
bpf_selem_unlink_storage() and bpf_selem_free_list() correspondingly.
bpf_local_storage_update() has been analyzed as the first caller above.
bpf_local_storage_destroy() is invoked when freeing the local storage
for the kernel object. Now cgroup, task, inode and sock storage have
already disabled migration before invoking bpf_local_storage_destroy().
After the analyses above, it is safe to remove migrate_{disable|enable}
from bpf_selem_free().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-17-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_local_storage_free() has three callers:
1) bpf_local_storage_alloc()
Its caller must have disabled migration.
2) bpf_local_storage_destroy()
Its four callers (bpf_{cgrp|inode|task|sk}_storage_free()) have already
invoked migrate_disable() before invoking bpf_local_storage_destroy().
3) bpf_selem_unlink()
Its callers include: cgrp/inode/task/sk storage ->map_delete_elem
callbacks, bpf_{cgrp|inode|task|sk}_storage_delete() helpers and
bpf_local_storage_map_free(). All of these callers have already disabled
migration before invoking bpf_selem_unlink().
Therefore, it is OK to remove migrate_{disable|enable} pair from
bpf_local_storage_free().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-16-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
These two callers of bpf_local_storage_alloc() are the same as
bpf_selem_alloc(): bpf_sk_storage_clone() and
bpf_local_storage_update(). The running contexts of these two callers
have already disabled migration, therefore, there is no need to add
extra migrate_{disable|enable} pair in bpf_local_storage_alloc().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-15-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_selem_alloc() has two callers:
(1) bpf_sk_storage_clone_elem()
bpf_sk_storage_clone() has already disabled migration before invoking
bpf_sk_storage_clone_elem().
(2) bpf_local_storage_update()
Its callers include: cgrp/task/inode/sock storage ->map_update_elem()
callbacks and bpf_{cgrp|task|inode|sk}_storage_get() helpers. These
running contexts have already disabled migration
Therefore, there is no need to add extra migrate_{disable|enable} pair
in bpf_selem_alloc().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-14-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When BPF program invokes bpf_cpumask_release(), the migration must have
been disabled. When bpf_cpumask_release_dtor() invokes
bpf_cpumask_release(), the caller bpf_obj_free_fields() also has
disabled migration, therefore, it is OK to remove the unnecessary
migrate_{disable|enable} pair in bpf_cpumask_release().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-13-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The callers of bpf_obj_free_fields() have already guaranteed that the
migration is disabled, therefore, there is no need to invoke
migrate_{disable,enable} pair in bpf_obj_free_fields()'s underly
implementation.
This patch removes unnecessary migrate_{disable|enable} pairs from
bpf_obj_free_fields() and its callees: bpf_list_head_free() and
bpf_rb_root_free().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-12-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The freeing of all map elements may invoke bpf_obj_free_fields() to free
the special fields in the map value. Since these special fields may be
allocated from bpf memory allocator, migrate_{disable|enable} pairs are
necessary for the freeing of these special fields.
To simplify reasoning about when migrate_disable() is needed for the
freeing of these special fields, let the caller to guarantee migration
is disabled before invoking bpf_obj_free_fields(). Therefore, disabling
migration before calling ops->map_free() to simplify the freeing of map
values or special fields allocated from bpf memory allocator.
After disabling migration in bpf_map_free(), there is no need for
additional migration_{disable|enable} pairs in these ->map_free()
callbacks. Remove these redundant invocations.
The migrate_{disable|enable} pairs in the underlying implementation of
bpf_obj_free_fields() will be removed by the following patch.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-11-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_selem_free_rcu() calls bpf_obj_free_fields() to free the special
fields in map value (e.g., kptr). Since kptrs may be allocated from bpf
memory allocator, migrate_{disable|enable} pairs are necessary for the
freeing of these kptrs.
To simplify reasoning about when migrate_disable() is needed for the
freeing of these dynamically-allocated kptrs, let the caller to
guarantee migration is disabled before invoking bpf_obj_free_fields().
Therefore, the patch adds migrate_{disable|enable} pair in
bpf_selem_free_rcu(). The migrate_{disable|enable} pairs in the
underlying implementation of bpf_obj_free_fields() will be removed by
the following patch.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-10-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When destroying inode storage, it invokes bpf_local_storage_destroy() to
remove all storage elements saved in the inode storage. The destroy
procedure will call bpf_selem_free() to free the element, and
bpf_selem_free() calls bpf_obj_free_fields() to free the special fields
in map value (e.g., kptr). Since kptrs may be allocated from bpf memory
allocator, migrate_{disable|enable} pairs are necessary for the freeing
of these kptrs.
To simplify reasoning about when migrate_disable() is needed for the
freeing of these dynamically-allocated kptrs, let the caller to
guarantee migration is disabled before invoking bpf_obj_free_fields().
Therefore, the patch adds migrate_{disable|enable} pair in
bpf_inode_storage_free(). The migrate_{disable|enable} pairs in the
underlying implementation of bpf_obj_free_fields() will be removed by
the following patch.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-7-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Three callers of bpf_task_storage_lock() are ->map_lookup_elem,
->map_update_elem, ->map_delete_elem from bpf syscall. BPF syscall for
these three operations of task storage has already disabled migration.
Another two callers are bpf_task_storage_get() and
bpf_task_storage_delete() helpers which will be used by BPF program.
Two callers of bpf_task_storage_trylock() are bpf_task_storage_get() and
bpf_task_storage_delete() helpers. The running contexts of these helpers
have already disabled migration.
Therefore, it is safe to remove migrate_{disable|enable} from task
storage lock helpers for these call sites. However,
bpf_task_storage_free() also invokes bpf_task_storage_lock() and its
running context doesn't disable migration, therefore, add the missed
migrate_{disable|enable} in bpf_task_storage_free().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-6-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Three callers of bpf_cgrp_storage_lock() are ->map_lookup_elem,
->map_update_elem, ->map_delete_elem from bpf syscall. BPF syscall for
these three operations of cgrp storage has already disabled migration.
Two call sites of bpf_cgrp_storage_trylock() are bpf_cgrp_storage_get(),
and bpf_cgrp_storage_delete() helpers. The running contexts of these
helpers have already disabled migration.
Therefore, it is safe to remove migrate_disable() for these callers.
However, bpf_cgrp_storage_free() also invokes bpf_cgrp_storage_lock()
and its running context doesn't disable migration. Therefore, also add
the missed migrate_{disabled|enable} in bpf_cgrp_storage_free().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
htab_elem_free() has two call-sites: delete_all_elements() has already
disabled migration, free_htab_elem() is invoked by other 4 functions:
__htab_map_lookup_and_delete_elem, __htab_map_lookup_and_delete_batch,
htab_map_update_elem and htab_map_delete_elem.
BPF syscall has already disabled migration before invoking
->map_update_elem, ->map_delete_elem, and ->map_lookup_and_delete_elem
callbacks for hash map. __htab_map_lookup_and_delete_batch() also
disables migration before invoking free_htab_elem(). ->map_update_elem()
and ->map_delete_elem() of hash map may be invoked by BPF program and
the running context of BPF program has already disabled migration.
Therefore, it is safe to remove the migration_{disable|enable} pair in
htab_elem_free()
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF program may call bpf_for_each_map_elem(), and it will call
the ->map_for_each_callback callback of related bpf map. Considering the
running context of bpf program has already disabled migration, remove
the unnecessary migrate_{disable|enable} pair in the implementations of
->map_for_each_callback. To ensure the guarantee will not be voilated
later, also add cant_migrate() check in the implementations.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Both bpf program and bpf syscall may invoke ->update or ->delete
operation for LPM trie. For bpf program, its running context has already
disabled migration explicitly through (migrate_disable()) or implicitly
through (preempt_disable() or disable irq). For bpf syscall, the
migration is disabled through the use of bpf_disable_instrumentation()
before invoking the corresponding map operation callback.
Therefore, it is safe to remove the migrate_{disable|enable){} pair from
LPM trie.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add the bpf_iter_num_* kfuncs called by bpf_for in special_kfunc_list,
and allow the calls even while holding a spin lock.
Signed-off-by: Emil Tsalapatis (Meta) <emil@etsalapatis.com>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250104202528.882482-2-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
There is a UAF report in the bpf_struct_ops when CONFIG_MODULES=n.
In particular, the report is on tcp_congestion_ops that has
a "struct module *owner" member.
For struct_ops that has a "struct module *owner" member,
it can be extended either by the regular kernel module or
by the bpf_struct_ops. bpf_try_module_get() will be used
to do the refcounting and different refcount is done
based on the owner pointer. When CONFIG_MODULES=n,
the btf_id of the "struct module" is missing:
WARN: resolve_btfids: unresolved symbol module
Thus, the bpf_try_module_get() cannot do the correct refcounting.
Not all subsystem's struct_ops requires the "struct module *owner" member.
e.g. the recent sched_ext_ops.
This patch is to disable bpf_struct_ops registration if
the struct_ops has the "struct module *" member and the
"struct module" btf_id is missing. The btf_type_is_fwd() helper
is moved to the btf.h header file for this test.
This has happened since the beginning of bpf_struct_ops which has gone
through many changes. The Fixes tag is set to a recent commit that this
patch can apply cleanly. Considering CONFIG_MODULES=n is not
common and the age of the issue, targeting for bpf-next also.
Fixes: 1611603537 ("bpf: Create argument information for nullable arguments.")
Reported-by: Robert Morris <rtm@csail.mit.edu>
Closes: https://lore.kernel.org/bpf/74665.1733669976@localhost/
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Tested-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241220201818.127152-1-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The range tree introduction removed the need for maple tree usage
but missed removing the MT_ENTRY defined value that was used to
mark maple tree allocated entries.
Remove the MT_ENTRY define.
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Link: https://lore.kernel.org/r/20241223115901.14207-1-lpieralisi@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch improves (or maintains) the precision of register value tracking
in BPF_MUL across all possible inputs. It also simplifies
scalar32_min_max_mul() and scalar_min_max_mul().
As it stands, BPF_MUL is composed of three functions:
case BPF_MUL:
tnum_mul();
scalar32_min_max_mul();
scalar_min_max_mul();
The current implementation of scalar_min_max_mul() restricts the u64 input
ranges of dst_reg and src_reg to be within [0, U32_MAX]:
/* Both values are positive, so we can work with unsigned and
* copy the result to signed (unless it exceeds S64_MAX).
*/
if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
/* Potential overflow, we know nothing */
__mark_reg64_unbounded(dst_reg);
return;
}
This restriction is done to avoid unsigned overflow, which could otherwise
wrap the result around 0, and leave an unsound output where umin > umax. We
also observe that limiting these u64 input ranges to [0, U32_MAX] leads to
a loss of precision. Consider the case where the u64 bounds of dst_reg are
[0, 2^34] and the u64 bounds of src_reg are [0, 2^2]. While the
multiplication of these two bounds doesn't overflow and is sound [0, 2^36],
the current scalar_min_max_mul() would set the entire register state to
unbounded.
Importantly, we update BPF_MUL to allow signed bound multiplication
(i.e. multiplying negative bounds) as well as allow u64 inputs to take on
values from [0, U64_MAX]. We perform signed multiplication on two bounds
[a,b] and [c,d] by multiplying every combination of the bounds
(i.e. a*c, a*d, b*c, and b*d) and checking for overflow of each product. If
there is an overflow, we mark the signed bounds unbounded [S64_MIN, S64_MAX].
In the case of no overflow, we take the minimum of these products to
be the resulting smin, and the maximum to be the resulting smax.
The key idea here is that if there’s no possibility of overflow, either
when multiplying signed bounds or unsigned bounds, we can safely multiply the
respective bounds; otherwise, we set the bounds that exhibit overflow
(during multiplication) to unbounded.
if (check_mul_overflow(*dst_umax, src_reg->umax_value, dst_umax) ||
(check_mul_overflow(*dst_umin, src_reg->umin_value, dst_umin))) {
/* Overflow possible, we know nothing */
*dst_umin = 0;
*dst_umax = U64_MAX;
}
...
Below, we provide an example BPF program (below) that exhibits the
imprecision in the current BPF_MUL, where the outputs are all unbounded. In
contrast, the updated BPF_MUL produces a bounded register state:
BPF_LD_IMM64(BPF_REG_1, 11),
BPF_LD_IMM64(BPF_REG_2, 4503599627370624),
BPF_ALU64_IMM(BPF_NEG, BPF_REG_2, 0),
BPF_ALU64_IMM(BPF_NEG, BPF_REG_2, 0),
BPF_ALU64_REG(BPF_AND, BPF_REG_1, BPF_REG_2),
BPF_LD_IMM64(BPF_REG_3, 809591906117232263),
BPF_ALU64_REG(BPF_MUL, BPF_REG_3, BPF_REG_1),
BPF_MOV64_IMM(BPF_REG_0, 1),
BPF_EXIT_INSN(),
Verifier log using the old BPF_MUL:
func#0 @0
0: R1=ctx() R10=fp0
0: (18) r1 = 0xb ; R1_w=11
2: (18) r2 = 0x10000000000080 ; R2_w=0x10000000000080
4: (87) r2 = -r2 ; R2_w=scalar()
5: (87) r2 = -r2 ; R2_w=scalar()
6: (5f) r1 &= r2 ; R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=11,var_off=(0x0; 0xb)) R2_w=scalar()
7: (18) r3 = 0xb3c3f8c99262687 ; R3_w=0xb3c3f8c99262687
9: (2f) r3 *= r1 ; R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=11,var_off=(0x0; 0xb)) R3_w=scalar()
...
Verifier using the new updated BPF_MUL (more precise bounds at label 9)
func#0 @0
0: R1=ctx() R10=fp0
0: (18) r1 = 0xb ; R1_w=11
2: (18) r2 = 0x10000000000080 ; R2_w=0x10000000000080
4: (87) r2 = -r2 ; R2_w=scalar()
5: (87) r2 = -r2 ; R2_w=scalar()
6: (5f) r1 &= r2 ; R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=11,var_off=(0x0; 0xb)) R2_w=scalar()
7: (18) r3 = 0xb3c3f8c99262687 ; R3_w=0xb3c3f8c99262687
9: (2f) r3 *= r1 ; R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=11,var_off=(0x0; 0xb)) R3_w=scalar(smin=0,smax=umax=0x7b96bb0a94a3a7cd,var_off=(0x0; 0x7fffffffffffffff))
...
Finally, we proved the soundness of the new scalar_min_max_mul() and
scalar32_min_max_mul() functions. Typically, multiplication operations are
expensive to check with bitvector-based solvers. We were able to prove the
soundness of these functions using Non-Linear Integer Arithmetic (NIA)
theory. Additionally, using Agni [2,3], we obtained the encodings for
scalar32_min_max_mul() and scalar_min_max_mul() in bitvector theory, and
were able to prove their soundness using 8-bit bitvectors (instead of
64-bit bitvectors that the functions actually use).
In conclusion, with this patch,
1. We were able to show that we can improve the overall precision of
BPF_MUL. We proved (using an SMT solver) that this new version of
BPF_MUL is at least as precise as the current version for all inputs
and more precise for some inputs.
2. We are able to prove the soundness of the new scalar_min_max_mul() and
scalar32_min_max_mul(). By leveraging the existing proof of tnum_mul
[1], we can say that the composition of these three functions within
BPF_MUL is sound.
[1] https://ieeexplore.ieee.org/abstract/document/9741267
[2] https://link.springer.com/chapter/10.1007/978-3-031-37709-9_12
[3] https://people.cs.rutgers.edu/~sn349/papers/sas24-preprint.pdf
Co-developed-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Signed-off-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Co-developed-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Signed-off-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Co-developed-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Matan Shachnai <m.shachnai@gmail.com>
Link: https://lore.kernel.org/r/20241218032337.12214-2-m.shachnai@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In PREEMPT_RT, kmalloc(GFP_ATOMIC) is still not safe in non preemptible
context. bpf_mem_alloc must be used in PREEMPT_RT. This patch is
to enforce bpf_mem_alloc in the bpf_local_storage when CONFIG_PREEMPT_RT
is enabled.
[ 35.118559] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
[ 35.118566] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1832, name: test_progs
[ 35.118569] preempt_count: 1, expected: 0
[ 35.118571] RCU nest depth: 1, expected: 1
[ 35.118577] INFO: lockdep is turned off.
...
[ 35.118647] __might_resched+0x433/0x5b0
[ 35.118677] rt_spin_lock+0xc3/0x290
[ 35.118700] ___slab_alloc+0x72/0xc40
[ 35.118723] __kmalloc_noprof+0x13f/0x4e0
[ 35.118732] bpf_map_kzalloc+0xe5/0x220
[ 35.118740] bpf_selem_alloc+0x1d2/0x7b0
[ 35.118755] bpf_local_storage_update+0x2fa/0x8b0
[ 35.118784] bpf_sk_storage_get_tracing+0x15a/0x1d0
[ 35.118791] bpf_prog_9a118d86fca78ebb_trace_inet_sock_set_state+0x44/0x66
[ 35.118795] bpf_trace_run3+0x222/0x400
[ 35.118820] __bpf_trace_inet_sock_set_state+0x11/0x20
[ 35.118824] trace_inet_sock_set_state+0x112/0x130
[ 35.118830] inet_sk_state_store+0x41/0x90
[ 35.118836] tcp_set_state+0x3b3/0x640
There is no need to adjust the gfp_flags passing to the
bpf_mem_cache_alloc_flags() which only honors the GFP_KERNEL.
The verifier has ensured GFP_KERNEL is passed only in sleepable context.
It has been an old issue since the first introduction of the
bpf_local_storage ~5 years ago, so this patch targets the bpf-next.
bpf_mem_alloc is needed to solve it, so the Fixes tag is set
to the commit when bpf_mem_alloc was first used in the bpf_local_storage.
Fixes: 08a7ce384e ("bpf: Use bpf_mem_cache_alloc/free in bpf_local_storage_elem")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241218193000.2084281-1-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
On x86-64 calling bpf_get_smp_processor_id() in a kernel with CONFIG_SMP
disabled can trigger the following bug, as pcpu_hot is unavailable:
[ 8.471774] BUG: unable to handle page fault for address: 00000000936a290c
[ 8.471849] #PF: supervisor read access in kernel mode
[ 8.471881] #PF: error_code(0x0000) - not-present page
Fix by inlining a return 0 in the !CONFIG_SMP case.
Fixes: 1ae6921009 ("bpf: inline bpf_get_smp_processor_id() helper")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241217195813.622568-1-arighi@nvidia.com
Arguments to a raw tracepoint are tagged as trusted, which carries the
semantics that the pointer will be non-NULL. However, in certain cases,
a raw tracepoint argument may end up being NULL. More context about this
issue is available in [0].
Thus, there is a discrepancy between the reality, that raw_tp arguments can
actually be NULL, and the verifier's knowledge, that they are never NULL,
causing explicit NULL check branch to be dead code eliminated.
A previous attempt [1], i.e. the second fixed commit, was made to
simulate symbolic execution as if in most accesses, the argument is a
non-NULL raw_tp, except for conditional jumps. This tried to suppress
branch prediction while preserving compatibility, but surfaced issues
with production programs that were difficult to solve without increasing
verifier complexity. A more complete discussion of issues and fixes is
available at [2].
Fix this by maintaining an explicit list of tracepoints where the
arguments are known to be NULL, and mark the positional arguments as
PTR_MAYBE_NULL. Additionally, capture the tracepoints where arguments
are known to be ERR_PTR, and mark these arguments as scalar values to
prevent potential dereference.
Each hex digit is used to encode NULL-ness (0x1) or ERR_PTR-ness (0x2),
shifted by the zero-indexed argument number x 4. This can be represented
as follows:
1st arg: 0x1
2nd arg: 0x10
3rd arg: 0x100
... and so on (likewise for ERR_PTR case).
In the future, an automated pass will be used to produce such a list, or
insert __nullable annotations automatically for tracepoints. Each
compilation unit will be analyzed and results will be collated to find
whether a tracepoint pointer is definitely not null, maybe null, or an
unknown state where verifier conservatively marks it PTR_MAYBE_NULL.
A proof of concept of this tool from Eduard is available at [3].
Note that in case we don't find a specification in the raw_tp_null_args
array and the tracepoint belongs to a kernel module, we will
conservatively mark the arguments as PTR_MAYBE_NULL. This is because
unlike for in-tree modules, out-of-tree module tracepoints may pass NULL
freely to the tracepoint. We don't protect against such tracepoints
passing ERR_PTR (which is uncommon anyway), lest we mark all such
arguments as SCALAR_VALUE.
While we are it, let's adjust the test raw_tp_null to not perform
dereference of the skb->mark, as that won't be allowed anymore, and make
it more robust by using inline assembly to test the dead code
elimination behavior, which should still stay the same.
[0]: https://lore.kernel.org/bpf/ZrCZS6nisraEqehw@jlelli-thinkpadt14gen4.remote.csb
[1]: https://lore.kernel.org/all/20241104171959.2938862-1-memxor@gmail.com
[2]: https://lore.kernel.org/bpf/20241206161053.809580-1-memxor@gmail.com
[3]: https://github.com/eddyz87/llvm-project/tree/nullness-for-tracepoint-params
Reported-by: Juri Lelli <juri.lelli@redhat.com> # original bug
Reported-by: Manu Bretelle <chantra@meta.com> # bugs in masking fix
Fixes: 3f00c52393 ("bpf: Allow trusted pointers to be passed to KF_TRUSTED_ARGS kfuncs")
Fixes: cb4158ce8e ("bpf: Mark raw_tp arguments with PTR_MAYBE_NULL")
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Co-developed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241213221929.3495062-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch reverts commit
cb4158ce8e ("bpf: Mark raw_tp arguments with PTR_MAYBE_NULL"). The
patch was well-intended and meant to be as a stop-gap fixing branch
prediction when the pointer may actually be NULL at runtime. Eventually,
it was supposed to be replaced by an automated script or compiler pass
detecting possibly NULL arguments and marking them accordingly.
However, it caused two main issues observed for production programs and
failed to preserve backwards compatibility. First, programs relied on
the verifier not exploring == NULL branch when pointer is not NULL, thus
they started failing with a 'dereference of scalar' error. Next,
allowing raw_tp arguments to be modified surfaced the warning in the
verifier that warns against reg->off when PTR_MAYBE_NULL is set.
More information, context, and discusson on both problems is available
in [0]. Overall, this approach had several shortcomings, and the fixes
would further complicate the verifier's logic, and the entire masking
scheme would have to be removed eventually anyway.
Hence, revert the patch in preparation of a better fix avoiding these
issues to replace this commit.
[0]: https://lore.kernel.org/bpf/20241206161053.809580-1-memxor@gmail.com
Reported-by: Manu Bretelle <chantra@meta.com>
Fixes: cb4158ce8e ("bpf: Mark raw_tp arguments with PTR_MAYBE_NULL")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241213221929.3495062-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
These BTF functions are not available unconditionally,
only reference them when they are available.
Avoid the following build warnings:
BTF .tmp_vmlinux1.btf.o
btf_encoder__tag_kfunc: failed to find kfunc 'bpf_send_signal_task' in BTF
btf_encoder__tag_kfuncs: failed to tag kfunc 'bpf_send_signal_task'
NM .tmp_vmlinux1.syms
KSYMS .tmp_vmlinux1.kallsyms.S
AS .tmp_vmlinux1.kallsyms.o
LD .tmp_vmlinux2
NM .tmp_vmlinux2.syms
KSYMS .tmp_vmlinux2.kallsyms.S
AS .tmp_vmlinux2.kallsyms.o
LD vmlinux
BTFIDS vmlinux
WARN: resolve_btfids: unresolved symbol prog_test_ref_kfunc
WARN: resolve_btfids: unresolved symbol bpf_crypto_ctx
WARN: resolve_btfids: unresolved symbol bpf_send_signal_task
WARN: resolve_btfids: unresolved symbol bpf_modify_return_test_tp
WARN: resolve_btfids: unresolved symbol bpf_dynptr_from_xdp
WARN: resolve_btfids: unresolved symbol bpf_dynptr_from_skb
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241213-bpf-cond-ids-v1-1-881849997219@weissschuh.net
The fd_array attribute of the BPF_PROG_LOAD syscall may contain a set
of file descriptors: maps or btfs. This field was introduced as a
sparse array. Introduce a new attribute, fd_array_cnt, which, if
present, indicates that the fd_array is a continuous array of the
corresponding length.
If fd_array_cnt is non-zero, then every map in the fd_array will be
bound to the program, as if it was used by the program. This
functionality is similar to the BPF_PROG_BIND_MAP syscall, but such
maps can be used by the verifier during the program load.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241213130934.1087929-5-aspsk@isovalent.com
Introduce a helper to add btfs to the env->used_maps array. Use it
to simplify the check_pseudo_btf_id() function. This new helper will
also be re-used in a consequent patch.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241213130934.1087929-4-aspsk@isovalent.com
Move some inlined map/prog compatibility checks from the
resolve_pseudo_ldimm64() function to the dedicated
check_map_prog_compatibility() function. Call the latter function
from the add_used_map_from_fd() function directly.
This simplifies code and optimizes logic a bit, as before these
changes the check_map_prog_compatibility() function was executed on
every map usage, which doesn't make sense, as it doesn't include any
per-instruction checks, only map type vs. prog type.
(This patch also simplifies a consequent patch which will call the
add_used_map_from_fd() function from another code path.)
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241213130934.1087929-3-aspsk@isovalent.com
Add a new helper to get a pointer to a struct btf from a file
descriptor. This helper doesn't increase a refcnt. Add a comment
explaining this and pointing to a corresponding function which
does take a reference.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241213130934.1087929-2-aspsk@isovalent.com
Initially, xdp_frame::mem.id was used to search for the corresponding
&page_pool to return the page correctly.
However, after that struct page was extended to have a direct pointer
to its PP (netmem has it as well), further keeping of this field makes
no sense. xdp_return_frame_bulk() still used it to do a lookup, and
this leftover is now removed.
Remove xdp_frame::mem and replace it with ::mem_type, as only memory
type still matters and we need to know it to be able to free the frame
correctly.
As a cute side effect, we can now make every scalar field in &xdp_frame
of 4 byte width, speeding up accesses to them.
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://patch.msgid.link/20241211172649.761483-3-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Robert Morris reported the following program type which passes the
verifier in [0]:
SEC("struct_ops/bpf_cubic_init")
void BPF_PROG(bpf_cubic_init, struct sock *sk)
{
asm volatile("r2 = *(u16*)(r1 + 0)"); // verifier should demand u64
asm volatile("*(u32 *)(r2 +1504) = 0"); // 1280 in some configs
}
The second line may or may not work, but the first instruction shouldn't
pass, as it's a narrow load into the context structure of the struct ops
callback. The code falls back to btf_ctx_access to ensure correctness
and obtaining the types of pointers. Ensure that the size of the access
is correctly checked to be 8 bytes, otherwise the verifier thinks the
narrow load obtained a trusted BTF pointer and will permit loads/stores
as it sees fit.
Perform the check on size after we've verified that the load is for a
pointer field, as for scalar values narrow loads are fine. Access to
structs passed as arguments to a BPF program are also treated as
scalars, therefore no adjustment is needed in their case.
Existing verifier selftests are broken by this change, but because they
were incorrect. Verifier tests for d_path were performing narrow load
into context to obtain path pointer, had this program actually run it
would cause a crash. The same holds for verifier_btf_ctx_access tests.
[0]: https://lore.kernel.org/bpf/51338.1732985814@localhost
Fixes: 9e15db6613 ("bpf: Implement accurate raw_tp context access via BTF")
Reported-by: Robert Morris <rtm@mit.edu>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241212092050.3204165-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_prog_aux->func field might be NULL if program does not have
subprograms except for main sub-program. The fixed commit does
bpf_prog_aux->func access unconditionally, which might lead to null
pointer dereference.
The bug could be triggered by replacing the following BPF program:
SEC("tc")
int main_changes(struct __sk_buff *sk)
{
bpf_skb_pull_data(sk, 0);
return 0;
}
With the following BPF program:
SEC("freplace")
long changes_pkt_data(struct __sk_buff *sk)
{
return bpf_skb_pull_data(sk, 0);
}
bpf_prog_aux instance itself represents the main sub-program,
use this property to fix the bug.
Fixes: 81f6d0530b ("bpf: check changes_pkt_data property for extension programs")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202412111822.qGw6tOyB-lkp@intel.com/
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241212070711.427443-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The bpf_remove_insns() function returns WARN_ON_ONCE(error), where
error is a result of bpf_adj_branches(), and thus should be always 0
However, if for any reason it is not 0, then it will be converted to
boolean by WARN_ON_ONCE and returned to user space as 1, not an actual
error value. Fix this by returning the original err after the WARN check.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20241210114245.836164-1-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When processing calls to global sub-programs, verifier decides whether
to invalidate all packet pointers in current state depending on the
changes_pkt_data property of the global sub-program.
Because of this, an extension program replacing a global sub-program
must be compatible with changes_pkt_data property of the sub-program
being replaced.
This commit:
- adds changes_pkt_data flag to struct bpf_prog_aux:
- this flag is set in check_cfg() for main sub-program;
- in jit_subprogs() for other sub-programs;
- modifies bpf_check_attach_btf_id() to check changes_pkt_data flag;
- moves call to check_attach_btf_id() after the call to check_cfg(),
because it needs changes_pkt_data flag to be set:
bpf_check:
... ...
- check_attach_btf_id resolve_pseudo_ldimm64
resolve_pseudo_ldimm64 --> bpf_prog_is_offloaded
bpf_prog_is_offloaded check_cfg
check_cfg + check_attach_btf_id
... ...
The following fields are set by check_attach_btf_id():
- env->ops
- prog->aux->attach_btf_trace
- prog->aux->attach_func_name
- prog->aux->attach_func_proto
- prog->aux->dst_trampoline
- prog->aux->mod
- prog->aux->saved_dst_attach_type
- prog->aux->saved_dst_prog_type
- prog->expected_attach_type
Neither of these fields are used by resolve_pseudo_ldimm64() or
bpf_prog_offload_verifier_prep() (for netronome and netdevsim
drivers), so the reordering is safe.
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When processing calls to certain helpers, verifier invalidates all
packet pointers in a current state. For example, consider the
following program:
__attribute__((__noinline__))
long skb_pull_data(struct __sk_buff *sk, __u32 len)
{
return bpf_skb_pull_data(sk, len);
}
SEC("tc")
int test_invalidate_checks(struct __sk_buff *sk)
{
int *p = (void *)(long)sk->data;
if ((void *)(p + 1) > (void *)(long)sk->data_end) return TCX_DROP;
skb_pull_data(sk, 0);
*p = 42;
return TCX_PASS;
}
After a call to bpf_skb_pull_data() the pointer 'p' can't be used
safely. See function filter.c:bpf_helper_changes_pkt_data() for a list
of such helpers.
At the moment verifier invalidates packet pointers when processing
helper function calls, and does not traverse global sub-programs when
processing calls to global sub-programs. This means that calls to
helpers done from global sub-programs do not invalidate pointers in
the caller state. E.g. the program above is unsafe, but is not
rejected by verifier.
This commit fixes the omission by computing field
bpf_subprog_info->changes_pkt_data for each sub-program before main
verification pass.
changes_pkt_data should be set if:
- subprogram calls helper for which bpf_helper_changes_pkt_data
returns true;
- subprogram calls a global function,
for which bpf_subprog_info->changes_pkt_data should be set.
The verifier.c:check_cfg() pass is modified to compute this
information. The commit relies on depth first instruction traversal
done by check_cfg() and absence of recursive function calls:
- check_cfg() would eventually visit every call to subprogram S in a
state when S is fully explored;
- when S is fully explored:
- every direct helper call within S is explored
(and thus changes_pkt_data is set if needed);
- every call to subprogram S1 called by S was visited with S1 fully
explored (and thus S inherits changes_pkt_data from S1).
The downside of such approach is that dead code elimination is not
taken into account: if a helper call inside global function is dead
because of current configuration, verifier would conservatively assume
that the call occurs for the purpose of the changes_pkt_data
computation.
Reported-by: Nick Zavaritsky <mejedi@gmail.com>
Closes: https://lore.kernel.org/bpf/0498CA22-5779-4767-9C0C-A9515CEA711F@gmail.com/
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Use BPF helper number instead of function pointer in
bpf_helper_changes_pkt_data(). This would simplify usage of this
function in verifier.c:check_cfg() (in a follow-up patch),
where only helper number is easily available and there is no real need
to lookup helper proto.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-3-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a utility function, looking for a subprogram containing a given
instruction index, rewrite find_subprog() to use this function.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
After switching from kmalloc() to the bpf memory allocator, there will be
no blocking operation during the update of LPM trie. Therefore, change
trie->lock from spinlock_t to raw_spinlock_t to make LPM trie usable in
atomic context, even on RT kernels.
The max value of prefixlen is 2048. Therefore, update or deletion
operations will find the target after at most 2048 comparisons.
Constructing a test case which updates an element after 2048 comparisons
under a 8 CPU VM, and the average time and the maximal time for such
update operation is about 210us and 900us.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-8-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Multiple syzbot warnings have been reported. These warnings are mainly
about the lock order between trie->lock and kmalloc()'s internal lock.
See report [1] as an example:
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc7-syzkaller-00003-g4376e966ecb7 #0 Not tainted
------------------------------------------------------
syz.3.2069/15008 is trying to acquire lock:
ffff88801544e6d8 (&n->list_lock){-.-.}-{2:2}, at: get_partial_node ...
but task is already holding lock:
ffff88802dcc89f8 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem ...
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&trie->lock){-.-.}-{2:2}:
__raw_spin_lock_irqsave
_raw_spin_lock_irqsave+0x3a/0x60
trie_delete_elem+0xb0/0x820
___bpf_prog_run+0x3e51/0xabd0
__bpf_prog_run32+0xc1/0x100
bpf_dispatcher_nop_func
......
bpf_trace_run2+0x231/0x590
__bpf_trace_contention_end+0xca/0x110
trace_contention_end.constprop.0+0xea/0x170
__pv_queued_spin_lock_slowpath+0x28e/0xcc0
pv_queued_spin_lock_slowpath
queued_spin_lock_slowpath
queued_spin_lock
do_raw_spin_lock+0x210/0x2c0
__raw_spin_lock_irqsave
_raw_spin_lock_irqsave+0x42/0x60
__put_partials+0xc3/0x170
qlink_free
qlist_free_all+0x4e/0x140
kasan_quarantine_reduce+0x192/0x1e0
__kasan_slab_alloc+0x69/0x90
kasan_slab_alloc
slab_post_alloc_hook
slab_alloc_node
kmem_cache_alloc_node_noprof+0x153/0x310
__alloc_skb+0x2b1/0x380
......
-> #0 (&n->list_lock){-.-.}-{2:2}:
check_prev_add
check_prevs_add
validate_chain
__lock_acquire+0x2478/0x3b30
lock_acquire
lock_acquire+0x1b1/0x560
__raw_spin_lock_irqsave
_raw_spin_lock_irqsave+0x3a/0x60
get_partial_node.part.0+0x20/0x350
get_partial_node
get_partial
___slab_alloc+0x65b/0x1870
__slab_alloc.constprop.0+0x56/0xb0
__slab_alloc_node
slab_alloc_node
__do_kmalloc_node
__kmalloc_node_noprof+0x35c/0x440
kmalloc_node_noprof
bpf_map_kmalloc_node+0x98/0x4a0
lpm_trie_node_alloc
trie_update_elem+0x1ef/0xe00
bpf_map_update_value+0x2c1/0x6c0
map_update_elem+0x623/0x910
__sys_bpf+0x90c/0x49a0
...
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&trie->lock);
lock(&n->list_lock);
lock(&trie->lock);
lock(&n->list_lock);
*** DEADLOCK ***
[1]: https://syzkaller.appspot.com/bug?extid=9045c0a3d5a7f1b119f7
A bpf program attached to trace_contention_end() triggers after
acquiring &n->list_lock. The program invokes trie_delete_elem(), which
then acquires trie->lock. However, it is possible that another
process is invoking trie_update_elem(). trie_update_elem() will acquire
trie->lock first, then invoke kmalloc_node(). kmalloc_node() may invoke
get_partial_node() and try to acquire &n->list_lock (not necessarily the
same lock object). Therefore, lockdep warns about the circular locking
dependency.
Invoking kmalloc() before acquiring trie->lock could fix the warning.
However, since BPF programs call be invoked from any context (e.g.,
through kprobe/tracepoint/fentry), there may still be lock ordering
problems for internal locks in kmalloc() or trie->lock itself.
To eliminate these potential lock ordering problems with kmalloc()'s
internal locks, replacing kmalloc()/kfree()/kfree_rcu() with equivalent
BPF memory allocator APIs that can be invoked in any context. The lock
ordering problems with trie->lock (e.g., reentrance) will be handled
separately.
Three aspects of this change require explanation:
1. Intermediate and leaf nodes are allocated from the same allocator.
Since the value size of LPM trie is usually small, using a single
alocator reduces the memory overhead of the BPF memory allocator.
2. Leaf nodes are allocated before disabling IRQs. This handles cases
where leaf_size is large (e.g., > 4KB - 8) and updates require
intermediate node allocation. If leaf nodes were allocated in
IRQ-disabled region, the free objects in BPF memory allocator would not
be refilled timely and the intermediate node allocation may fail.
3. Paired migrate_{disable|enable}() calls for node alloc and free. The
BPF memory allocator uses per-CPU struct internally, these paired calls
are necessary to guarantee correctness.
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-7-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
trie_get_next_key() uses node->prefixlen == key->prefixlen to identify
an exact match, However, it is incorrect because when the target key
doesn't fully match the found node (e.g., node->prefixlen != matchlen),
these two nodes may also have the same prefixlen. It will return
expected result when the passed key exist in the trie. However when a
recently-deleted key or nonexistent key is passed to
trie_get_next_key(), it may skip keys and return incorrect result.
Fix it by using node->prefixlen == matchlen to identify exact matches.
When the condition is true after the search, it also implies
node->prefixlen equals key->prefixlen, otherwise, the search would
return NULL instead.
Fixes: b471f2f1de ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-6-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When a LPM trie is full, in-place updates of existing elements
incorrectly return -ENOSPC.
Fix this by deferring the check of trie->n_entries. For new insertions,
n_entries must not exceed max_entries. However, in-place updates are
allowed even when the trie is full.
Fixes: b95a5c4db0 ("bpf: add a longest prefix match trie map implementation")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add the currently missing handling for the BPF_EXIST and BPF_NOEXIST
flags. These flags can be specified by users and are relevant since LPM
trie supports exact matches during update.
Fixes: b95a5c4db0 ("bpf: add a longest prefix match trie map implementation")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
There is no need to call kfree(im_node) when updating element fails,
because im_node must be NULL. Remove the unnecessary kfree() for
im_node.
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When "node->prefixlen == matchlen" is true, it means that the node is
fully matched. If "node->prefixlen == key->prefixlen" is false, it means
the prefix length of key is greater than the prefix length of node,
otherwise, matchlen will not be equal with node->prefixlen. However, it
also implies that the prefix length of node must be less than
max_prefixlen.
Therefore, "node->prefixlen == trie->max_prefixlen" will always be false
when the check of "node->prefixlen == key->prefixlen" returns false.
Remove this unnecessary comparison.
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In lots of places, bpf_prog pointer is used only for tracing or other
stuff that doesn't modify the structure itself. Same for net_device.
Address at least some of them and add `const` attributes there. The
object code didn't change, but that may prevent unwanted data
modifications and also allow more helpers to have const arguments.
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When CAP_PERFMON and CAP_SYS_ADMIN (allow_ptr_leaks) are disabled, the
verifier aims to reject partial overwrite on an 8-byte stack slot that
contains a spilled pointer.
However, in such a scenario, it rejects all partial stack overwrites as
long as the targeted stack slot is a spilled register, because it does
not check if the stack slot is a spilled pointer.
Incomplete checks will result in the rejection of valid programs, which
spill narrower scalar values onto scalar slots, as shown below.
0: R1=ctx() R10=fp0
; asm volatile ( @ repro.bpf.c:679
0: (7a) *(u64 *)(r10 -8) = 1 ; R10=fp0 fp-8_w=1
1: (62) *(u32 *)(r10 -8) = 1
attempt to corrupt spilled pointer on stack
processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0.
Fix this by expanding the check to not consider spilled scalar registers
when rejecting the write into the stack.
Previous discussion on this patch is at link [0].
[0]: https://lore.kernel.org/bpf/20240403202409.2615469-1-tao.lyu@epfl.ch
Fixes: ab125ed3ec ("bpf: fix check for attempt to corrupt spilled pointer")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Tao Lyu <tao.lyu@epfl.ch>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204044757.1483141-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Inside mark_stack_slot_misc, we should not upgrade STACK_INVALID to
STACK_MISC when allow_ptr_leaks is false, since invalid contents
shouldn't be read unless the program has the relevant capabilities.
The relaxation only makes sense when env->allow_ptr_leaks is true.
However, such conversion in privileged mode becomes unnecessary, as
invalid slots can be read without being upgraded to STACK_MISC.
Currently, the condition is inverted (i.e. checking for true instead of
false), simply remove it to restore correct behavior.
Fixes: eaf18febd6 ("bpf: preserve STACK_ZERO slots on partial reg spills")
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Reported-by: Tao Lyu <tao.lyu@epfl.ch>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204044757.1483141-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The verifier log when leaking resources on BPF_EXIT may be a bit
confusing, as it's a problem only when finally existing from the main
prog, not from any of the subprogs. Hence, update the verifier error
string and the corresponding selftests matching on it.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204030400.208005-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Teach the verifier about IRQ-disabled sections through the introduction
of two new kfuncs, bpf_local_irq_save, to save IRQ state and disable
them, and bpf_local_irq_restore, to restore IRQ state and enable them
back again.
For the purposes of tracking the saved IRQ state, the verifier is taught
about a new special object on the stack of type STACK_IRQ_FLAG. This is
a 8 byte value which saves the IRQ flags which are to be passed back to
the IRQ restore kfunc.
Renumber the enums for REF_TYPE_* to simplify the check in
find_lock_state, filtering out non-lock types as they grow will become
cumbersome and is unecessary.
To track a dynamic number of IRQ-disabled regions and their associated
saved states, a new resource type RES_TYPE_IRQ is introduced, which its
state management functions: acquire_irq_state and release_irq_state,
taking advantage of the refactoring and clean ups made in earlier
commits.
One notable requirement of the kernel's IRQ save and restore API is that
they cannot happen out of order. For this purpose, when releasing reference
we keep track of the prev_id we saw with REF_TYPE_IRQ. Since reference
states are inserted in increasing order of the index, this is used to
remember the ordering of acquisitions of IRQ saved states, so that we
maintain a logical stack in acquisition order of resource identities,
and can enforce LIFO ordering when restoring IRQ state. The top of the
stack is maintained using bpf_verifier_state's active_irq_id.
To maintain the stack property when releasing reference states, we need
to modify release_reference_state to instead shift the remaining array
left using memmove instead of swapping deleted element with last that
might break the ordering. A selftest to test this subtle behavior is
added in late patches.
The logic to detect initialized and unitialized irq flag slots, marking
and unmarking is similar to how it's done for iterators. No additional
checks are needed in refsafe for REF_TYPE_IRQ, apart from the usual
check_id satisfiability check on the ref[i].id. We have to perform the
same check_ids check on state->active_irq_id as well.
To ensure we don't get assigned REF_TYPE_PTR by default after
acquire_reference_state, if someone forgets to assign the type, let's
also renumber the enum ref_state_type. This way any unassigned types
get caught by refsafe's default switch statement, don't assume
REF_TYPE_PTR by default.
The kfuncs themselves are plain wrappers over local_irq_save and
local_irq_restore macros.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204030400.208005-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
There is possibility of sharing code between mark_dynptr_read and
mark_iter_read for updating liveness information of their stack slots.
Consolidate common logic into mark_stack_slot_obj_read function in
preparation for the next patch which needs the same logic for its own
stack slots.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204030400.208005-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In preparation for introducing support for more reference types which
have to add and remove reference state, refactor the
acquire_reference_state and release_reference_state functions to share
common logic.
The acquire_reference_state function simply handles growing the acquired
refs and returning the pointer to the new uninitialized element, which
can be filled in by the caller.
The release_reference_state function simply erases a reference state
entry in the acquired_refs array and shrinks it. The callers are
responsible for finding the suitable element by matching on various
fields of the reference state and requesting deletion through this
function. It is not supposed to be called directly.
Existing callers of release_reference_state were using it to find and
remove state for a given ref_obj_id without scrubbing the associated
registers in the verifier state. Introduce release_reference_nomark to
provide this functionality and convert callers. We now use this new
release_reference_nomark function within release_reference as well.
It needs to operate on a verifier state instead of taking verifier env
as mark_ptr_or_null_regs requires operating on verifier state of the
two branches of a NULL condition check, therefore env->cur_state cannot
be used directly.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204030400.208005-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, state for RCU read locks and preemption is in
bpf_verifier_state, while locks and pointer reference state remains in
bpf_func_state. There is no particular reason to keep the latter in
bpf_func_state. Additionally, it is copied into a new frame's state and
copied back to the caller frame's state everytime the verifier processes
a pseudo call instruction. This is a bit wasteful, given this state is
global for a given verification state / path.
Move all resource and reference related state in bpf_verifier_state
structure in this patch, in preparation for introducing new reference
state types in the future.
Since we switch print_verifier_state and friends to print using vstate,
we now need to explicitly pass in the verifier state from the caller
along with the bpf_func_state, so modify the prototype and callers to do
so. To ensure func state matches the verifier state when we're printing
data, take in frame number instead of bpf_func_state pointer instead and
avoid inconsistencies induced by the caller.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204030400.208005-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Andrii spotted that process_dynptr_func's rejection of incorrect
argument register type will print an error string where argument numbers
are not zero-indexed, unlike elsewhere in the verifier. Fix this by
subtracting 1 from regno. The same scenario exists for iterator
messages. Fix selftest error strings that match on the exact argument
number while we're at it to ensure clean bisection.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241203002235.3776418-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, KF_ARG_PTR_TO_ITER handling missed checking the reg->type and
ensuring it is PTR_TO_STACK. Instead of enforcing this in the caller of
process_iter_arg, move the check into it instead so that all callers
will gain the check by default. This is similar to process_dynptr_func.
An existing selftest in verifier_bits_iter.c fails due to this change,
but it's because it was passing a NULL pointer into iter_next helper and
getting an error further down the checks, but probably meant to pass an
uninitialized iterator on the stack (as is done in the subsequent test
below it). We will gain coverage for non-PTR_TO_STACK arguments in later
patches hence just change the declaration to zero-ed stack object.
Fixes: 06accc8779 ("bpf: add support for open-coded iterator loops")
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Tao Lyu <tao.lyu@epfl.ch>
[ Kartikeya: move check into process_iter_arg, rewrite commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241203000238.3602922-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
* sysctl ctl_table constification
Constifying ctl_table structs prevents the modification of proc_handler
function pointers. All ctl_table struct arguments are const qualified in the
sysctl API in such a way that the ctl_table arrays being defined elsewhere
and passed through sysctl can be constified one-by-one. We kick the
constification off by qualifying user_table in kernel/ucount.c and expect all
the ctl_tables to be constified in the coming releases.
* Misc fixes
Adjust comments in two places to better reflect the code. Remove superfluous
dput calls. Remove Luis from sysctl maintainership. Replace comments about
holding a lock with calls to lockdep_assert_held.
* Testing
All these went through 0-day and they have all been in linux-next for at
least 1 month (since Oct-24). I also rand these through the sysctl selftest
for x86_64.
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Merge tag 'sysctl-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl
Pull sysctl updates from Joel Granados:
"sysctl ctl_table constification:
- Constifying ctl_table structs prevents the modification of
proc_handler function pointers. All ctl_table struct arguments are
const qualified in the sysctl API in such a way that the ctl_table
arrays being defined elsewhere and passed through sysctl can be
constified one-by-one.
We kick the constification off by qualifying user_table in
kernel/ucount.c and expect all the ctl_tables to be constified in
the coming releases.
Misc fixes:
- Adjust comments in two places to better reflect the code
- Remove superfluous dput calls
- Remove Luis from sysctl maintainership
- Replace comments about holding a lock with calls to
lockdep_assert_held"
* tag 'sysctl-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
sysctl: Reduce dput(child) calls in proc_sys_fill_cache()
sysctl: Reorganize kerneldoc parameter names
ucounts: constify sysctl table user_table
sysctl: update comments to new registration APIs
MAINTAINERS: remove me from sysctl
sysctl: Convert locking comments to lockdep assertions
const_structs.checkpatch: add ctl_table
sysctl: make internal ctl_tables const
sysctl: allow registration of const struct ctl_table
sysctl: move internal interfaces to const struct ctl_table
bpf: Constify ctl_table argument of filter function
- Addition of faultable tracepoints
There's a tracepoint attached to both a system call entry and exit. This
location is known to allow page faults. The tracepoints are called under
an rcu_read_lock() which does not allow faults that can sleep. This limits
the ability of tracepoint handlers to page fault in user space system call
parameters. Now these tracepoints have been made "faultable", allowing the
callbacks to fault in user space parameters and record them.
Note, only the infrastructure has been implemented. The consumers (perf,
ftrace, BPF) now need to have their code modified to allow faults.
- Fix up of BPF code for the tracepoint faultable logic
- Update tracepoints to use the new static branch API
- Remove trace_*_rcuidle() variants and the SRCU protection they used
- Remove unused TRACE_EVENT_FL_FILTERED logic
- Replace strncpy() with strscpy() and memcpy()
- Use replace per_cpu_ptr(smp_processor_id()) with this_cpu_ptr()
- Fix perf events to not duplicate samples when tracing is enabled
- Replace atomic64_add_return(1, counter) with atomic64_inc_return(counter)
- Make stack trace buffer 4K instead of PAGE_SIZE
- Remove TRACE_FLAG_IRQS_NOSUPPORT flag as it was never used
- Get the true return address for function tracer when function graph tracer
is also running.
When function_graph trace is running along with function tracer,
the parent function of the function tracer sometimes is
"return_to_handler", which is the function graph trampoline to record
the exit of the function. Use existing logic that calls into the
fgraph infrastructure to find the real return address.
- Remove (un)regfunc pointers out of tracepoint structure
- Added last minute bug fix for setting pending modules in stack function
filter.
echo "write*:mod:ext3" > /sys/kernel/tracing/stack_trace_filter
Would cause a kernel NULL dereference.
- Minor clean ups
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Merge tag 'trace-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt:
- Addition of faultable tracepoints
There's a tracepoint attached to both a system call entry and exit.
This location is known to allow page faults. The tracepoints are
called under an rcu_read_lock() which does not allow faults that can
sleep. This limits the ability of tracepoint handlers to page fault
in user space system call parameters. Now these tracepoints have been
made "faultable", allowing the callbacks to fault in user space
parameters and record them.
Note, only the infrastructure has been implemented. The consumers
(perf, ftrace, BPF) now need to have their code modified to allow
faults.
- Fix up of BPF code for the tracepoint faultable logic
- Update tracepoints to use the new static branch API
- Remove trace_*_rcuidle() variants and the SRCU protection they used
- Remove unused TRACE_EVENT_FL_FILTERED logic
- Replace strncpy() with strscpy() and memcpy()
- Use replace per_cpu_ptr(smp_processor_id()) with this_cpu_ptr()
- Fix perf events to not duplicate samples when tracing is enabled
- Replace atomic64_add_return(1, counter) with
atomic64_inc_return(counter)
- Make stack trace buffer 4K instead of PAGE_SIZE
- Remove TRACE_FLAG_IRQS_NOSUPPORT flag as it was never used
- Get the true return address for function tracer when function graph
tracer is also running.
When function_graph trace is running along with function tracer, the
parent function of the function tracer sometimes is
"return_to_handler", which is the function graph trampoline to record
the exit of the function. Use existing logic that calls into the
fgraph infrastructure to find the real return address.
- Remove (un)regfunc pointers out of tracepoint structure
- Added last minute bug fix for setting pending modules in stack
function filter.
echo "write*:mod:ext3" > /sys/kernel/tracing/stack_trace_filter
Would cause a kernel NULL dereference.
- Minor clean ups
* tag 'trace-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (31 commits)
ftrace: Fix regression with module command in stack_trace_filter
tracing: Fix function name for trampoline
ftrace: Get the true parent ip for function tracer
tracing: Remove redundant check on field->field in histograms
bpf: ensure RCU Tasks Trace GP for sleepable raw tracepoint BPF links
bpf: decouple BPF link/attach hook and BPF program sleepable semantics
bpf: put bpf_link's program when link is safe to be deallocated
tracing: Replace strncpy() with strscpy() when copying comm
tracing: Add might_fault() check in __DECLARE_TRACE_SYSCALL
tracing: Fix syscall tracepoint use-after-free
tracing: Introduce tracepoint_is_faultable()
tracing: Introduce tracepoint extended structure
tracing: Remove TRACE_FLAG_IRQS_NOSUPPORT
tracing: Replace multiple deprecated strncpy with memcpy
tracing: Make percpu stack trace buffer invariant to PAGE_SIZE
tracing: Use atomic64_inc_return() in trace_clock_counter()
trace/trace_event_perf: remove duplicate samples on the first tracepoint event
tracing/bpf: Add might_fault check to syscall probes
tracing/perf: Add might_fault check to syscall probes
tracing/ftrace: Add might_fault check to syscall probes
...
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Merge tag 'bpf-next-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf updates from Alexei Starovoitov:
- Add BPF uprobe session support (Jiri Olsa)
- Optimize uprobe performance (Andrii Nakryiko)
- Add bpf_fastcall support to helpers and kfuncs (Eduard Zingerman)
- Avoid calling free_htab_elem() under hash map bucket lock (Hou Tao)
- Prevent tailcall infinite loop caused by freplace (Leon Hwang)
- Mark raw_tracepoint arguments as nullable (Kumar Kartikeya Dwivedi)
- Introduce uptr support in the task local storage map (Martin KaFai
Lau)
- Stringify errno log messages in libbpf (Mykyta Yatsenko)
- Add kmem_cache BPF iterator for perf's lock profiling (Namhyung Kim)
- Support BPF objects of either endianness in libbpf (Tony Ambardar)
- Add ksym to struct_ops trampoline to fix stack trace (Xu Kuohai)
- Introduce private stack for eligible BPF programs (Yonghong Song)
- Migrate samples/bpf tests to selftests/bpf test_progs (Daniel T. Lee)
- Migrate test_sock to selftests/bpf test_progs (Jordan Rife)
* tag 'bpf-next-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (152 commits)
libbpf: Change hash_combine parameters from long to unsigned long
selftests/bpf: Fix build error with llvm 19
libbpf: Fix memory leak in bpf_program__attach_uprobe_multi
bpf: use common instruction history across all states
bpf: Add necessary migrate_disable to range_tree.
bpf: Do not alloc arena on unsupported arches
selftests/bpf: Set test path for token/obj_priv_implicit_token_envvar
selftests/bpf: Add a test for arena range tree algorithm
bpf: Introduce range_tree data structure and use it in bpf arena
samples/bpf: Remove unused variable in xdp2skb_meta_kern.c
samples/bpf: Remove unused variables in tc_l2_redirect_kern.c
bpftool: Cast variable `var` to long long
bpf, x86: Propagate tailcall info only for subprogs
bpf: Add kernel symbol for struct_ops trampoline
bpf: Use function pointers count as struct_ops links count
bpf: Remove unused member rcu from bpf_struct_ops_map
selftests/bpf: Add struct_ops prog private stack tests
bpf: Support private stack for struct_ops progs
selftests/bpf: Add tracing prog private stack tests
bpf, x86: Support private stack in jit
...
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Merge tag 'random-6.13-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator updates from Jason Donenfeld:
"This contains a single series from Uros to replace uses of
<linux/random.h> with prandom.h or other more specific headers
as needed, in order to avoid a circular header issue.
Uros' goal is to be able to use percpu.h from prandom.h, which
will then allow him to define __percpu in percpu.h rather than
in compiler_types.h"
* tag 'random-6.13-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
prandom: Include <linux/percpu.h> in <linux/prandom.h>
random: Do not include <linux/prandom.h> in <linux/random.h>
netem: Include <linux/prandom.h> in sch_netem.c
lib/test_scanf: Include <linux/prandom.h> instead of <linux/random.h>
lib/test_parman: Include <linux/prandom.h> instead of <linux/random.h>
bpf/tests: Include <linux/prandom.h> instead of <linux/random.h>
lib/rbtree-test: Include <linux/prandom.h> instead of <linux/random.h>
random32: Include <linux/prandom.h> instead of <linux/random.h>
kunit: string-stream-test: Include <linux/prandom.h>
lib/interval_tree_test.c: Include <linux/prandom.h> instead of <linux/random.h>
bpf: Include <linux/prandom.h> instead of <linux/random.h>
scsi: libfcoe: Include <linux/prandom.h> instead of <linux/random.h>
fscrypt: Include <linux/once.h> in fs/crypto/keyring.c
mtd: tests: Include <linux/prandom.h> instead of <linux/random.h>
media: vivid: Include <linux/prandom.h> in vivid-vid-cap.c
drm/lib: Include <linux/prandom.h> instead of <linux/random.h>
drm/i915/selftests: Include <linux/prandom.h> instead of <linux/random.h>
crypto: testmgr: Include <linux/prandom.h> instead of <linux/random.h>
x86/kaslr: Include <linux/prandom.h> instead of <linux/random.h>
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Merge tag 'vfs-6.13.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs file updates from Christian Brauner:
"This contains changes the changes for files for this cycle:
- Introduce a new reference counting mechanism for files.
As atomic_inc_not_zero() is implemented with a try_cmpxchg() loop
it has O(N^2) behaviour under contention with N concurrent
operations and it is in a hot path in __fget_files_rcu().
The rcuref infrastructures remedies this problem by using an
unconditional increment relying on safe- and dead zones to make
this work and requiring rcu protection for the data structure in
question. This not just scales better it also introduces overflow
protection.
However, in contrast to generic rcuref, files require a memory
barrier and thus cannot rely on *_relaxed() atomic operations and
also require to be built on atomic_long_t as having massive amounts
of reference isn't unheard of even if it is just an attack.
This adds a file specific variant instead of making this a generic
library.
This has been tested by various people and it gives consistent
improvement up to 3-5% on workloads with loads of threads.
- Add a fastpath for find_next_zero_bit(). Skip 2-levels searching
via find_next_zero_bit() when there is a free slot in the word that
contains the next fd. This improves pts/blogbench-1.1.0 read by 8%
and write by 4% on Intel ICX 160.
- Conditionally clear full_fds_bits since it's very likely that a bit
in full_fds_bits has been cleared during __clear_open_fds(). This
improves pts/blogbench-1.1.0 read up to 13%, and write up to 5% on
Intel ICX 160.
- Get rid of all lookup_*_fdget_rcu() variants. They were used to
lookup files without taking a reference count. That became invalid
once files were switched to SLAB_TYPESAFE_BY_RCU and now we're
always taking a reference count. Switch to an already existing
helper and remove the legacy variants.
- Remove pointless includes of <linux/fdtable.h>.
- Avoid cmpxchg() in close_files() as nobody else has a reference to
the files_struct at that point.
- Move close_range() into fs/file.c and fold __close_range() into it.
- Cleanup calling conventions of alloc_fdtable() and expand_files().
- Merge __{set,clear}_close_on_exec() into one.
- Make __set_open_fd() set cloexec as well instead of doing it in two
separate steps"
* tag 'vfs-6.13.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests: add file SLAB_TYPESAFE_BY_RCU recycling stressor
fs: port files to file_ref
fs: add file_ref
expand_files(): simplify calling conventions
make __set_open_fd() set cloexec state as well
fs: protect backing files with rcu
file.c: merge __{set,clear}_close_on_exec()
alloc_fdtable(): change calling conventions.
fs/file.c: add fast path in find_next_fd()
fs/file.c: conditionally clear full_fds
fs/file.c: remove sanity_check and add likely/unlikely in alloc_fd()
move close_range(2) into fs/file.c, fold __close_range() into it
close_files(): don't bother with xchg()
remove pointless includes of <linux/fdtable.h>
get rid of ...lookup...fdget_rcu() family
Instead of allocating and copying instruction history each time we
enqueue child verifier state, switch to a model where we use one common
dynamically sized array of instruction history entries across all states.
The key observation for proving this is correct is that instruction
history is only relevant while state is active, which means it either is
a current state (and thus we are actively modifying instruction history
and no other state can interfere with us) or we are checkpointed state
with some children still active (either enqueued or being current).
In the latter case our portion of instruction history is finalized and
won't change or grow, so as long as we keep it immutable until the state
is finalized, we are good.
Now, when state is finalized and is put into state hash for potentially
future pruning lookups, instruction history is not used anymore. This is
because instruction history is only used by precision marking logic, and
we never modify precision markings for finalized states.
So, instead of each state having its own small instruction history, we
keep a global dynamically-sized instruction history, where each state in
current DFS path from root to active state remembers its portion of
instruction history. Current state can append to this history, but
cannot modify any of its parent histories.
Async callback state enqueueing, while logically detached from parent
state, still is part of verification backtracking tree, so has to follow
the same schema as normal state checkpoints.
Because the insn_hist array can be grown through realloc, states don't
keep pointers, they instead maintain two indices, [start, end), into
global instruction history array. End is exclusive index, so
`start == end` means there is no relevant instruction history.
This eliminates a lot of allocations and minimizes overall memory usage.
For instance, running a worst-case test from [0] (but without the
heuristics-based fix [1]), it took 12.5 minutes until we get -ENOMEM.
With the changes in this patch the whole test succeeds in 10 minutes
(very slow, so heuristics from [1] is important, of course).
To further validate correctness, veristat-based comparison was performed for
Meta production BPF objects and BPF selftests objects. In both cases there
were no differences *at all* in terms of verdict or instruction and state
counts, providing a good confidence in the change.
Having this low-memory-overhead solution of keeping dynamic
per-instruction history cheaply opens up some new possibilities, like
keeping extra information for literally every single validated
instruction. This will be used for simplifying precision backpropagation
logic in follow up patches.
[0] https://lore.kernel.org/bpf/20241029172641.1042523-2-eddyz87@gmail.com/
[1] https://lore.kernel.org/bpf/20241029172641.1042523-1-eddyz87@gmail.com/
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20241115001303.277272-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When running bpf selftest (./test_progs -j), the following warnings
showed up:
$ ./test_progs -t arena_atomics
...
BUG: using smp_processor_id() in preemptible [00000000] code: kworker/u19:0/12501
caller is bpf_mem_free+0x128/0x330
...
Call Trace:
<TASK>
dump_stack_lvl
check_preemption_disabled
bpf_mem_free
range_tree_destroy
arena_map_free
bpf_map_free_deferred
process_scheduled_works
...
For selftests arena_htab and arena_list, similar smp_process_id() BUGs are
dumped, and the following are two stack trace:
<TASK>
dump_stack_lvl
check_preemption_disabled
bpf_mem_alloc
range_tree_set
arena_map_alloc
map_create
...
<TASK>
dump_stack_lvl
check_preemption_disabled
bpf_mem_alloc
range_tree_clear
arena_vm_fault
do_pte_missing
handle_mm_fault
do_user_addr_fault
...
Add migrate_{disable,enable}() around related bpf_mem_{alloc,free}()
calls to fix the issue.
Fixes: b795379757 ("bpf: Introduce range_tree data structure and use it in bpf arena")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20241115060354.2832495-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introduce range_tree data structure and use it in bpf arena to track
ranges of allocated pages. range_tree is a large bitmap that is
implemented as interval tree plus rbtree. The contiguous sequence of
bits represents unallocated pages.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20241108025616.17625-2-alexei.starovoitov@gmail.com
Cross-merge bpf fixes after downstream PR.
In particular to bring the fix in
commit aa30eb3260 ("bpf: Force checkpoint when jmp history is too long").
The follow up verifier work depends on it.
And the fix in
commit 6801cf7890 ("selftests/bpf: Use -4095 as the bad address for bits iterator").
It's fixing instability of BPF CI on s390 arch.
No conflicts.
Adjacent changes in:
Auto-merging arch/Kconfig
Auto-merging kernel/bpf/helpers.c
Auto-merging kernel/bpf/memalloc.c
Auto-merging kernel/bpf/verifier.c
Auto-merging mm/slab_common.c
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Without kernel symbols for struct_ops trampoline, the unwinder may
produce unexpected stacktraces.
For example, the x86 ORC and FP unwinders check if an IP is in kernel
text by verifying the presence of the IP's kernel symbol. When a
struct_ops trampoline address is encountered, the unwinder stops due
to the absence of symbol, resulting in an incomplete stacktrace that
consists only of direct and indirect child functions called from the
trampoline.
The arm64 unwinder is another example. While the arm64 unwinder can
proceed across a struct_ops trampoline address, the corresponding
symbol name is displayed as "unknown", which is confusing.
Thus, add kernel symbol for struct_ops trampoline. The name is
bpf__<struct_ops_name>_<member_name>, where <struct_ops_name> is the
type name of the struct_ops, and <member_name> is the name of
the member that the trampoline is linked to.
Below is a comparison of stacktraces captured on x86 by perf record,
before and after this patch.
Before:
ffffffff8116545d __lock_acquire+0xad ([kernel.kallsyms])
ffffffff81167fcc lock_acquire+0xcc ([kernel.kallsyms])
ffffffff813088f4 __bpf_prog_enter+0x34 ([kernel.kallsyms])
After:
ffffffff811656bd __lock_acquire+0x30d ([kernel.kallsyms])
ffffffff81167fcc lock_acquire+0xcc ([kernel.kallsyms])
ffffffff81309024 __bpf_prog_enter+0x34 ([kernel.kallsyms])
ffffffffc000d7e9 bpf__tcp_congestion_ops_cong_avoid+0x3e ([kernel.kallsyms])
ffffffff81f250a5 tcp_ack+0x10d5 ([kernel.kallsyms])
ffffffff81f27c66 tcp_rcv_established+0x3b6 ([kernel.kallsyms])
ffffffff81f3ad03 tcp_v4_do_rcv+0x193 ([kernel.kallsyms])
ffffffff81d65a18 __release_sock+0xd8 ([kernel.kallsyms])
ffffffff81d65af4 release_sock+0x34 ([kernel.kallsyms])
ffffffff81f15c4b tcp_sendmsg+0x3b ([kernel.kallsyms])
ffffffff81f663d7 inet_sendmsg+0x47 ([kernel.kallsyms])
ffffffff81d5ab40 sock_write_iter+0x160 ([kernel.kallsyms])
ffffffff8149c67b vfs_write+0x3fb ([kernel.kallsyms])
ffffffff8149caf6 ksys_write+0xc6 ([kernel.kallsyms])
ffffffff8149cb5d __x64_sys_write+0x1d ([kernel.kallsyms])
ffffffff81009200 x64_sys_call+0x1d30 ([kernel.kallsyms])
ffffffff82232d28 do_syscall_64+0x68 ([kernel.kallsyms])
ffffffff8240012f entry_SYSCALL_64_after_hwframe+0x76 ([kernel.kallsyms])
Fixes: 85d33df357 ("bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS")
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20241112145849.3436772-4-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Only function pointers in a struct_ops structure can be linked to bpf
progs, so set the links count to the function pointers count, instead
of the total members count in the structure.
Suggested-by: Martin KaFai Lau <martin.lau@linux.dev>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20241112145849.3436772-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The rcu member in bpf_struct_ops_map is not used after commit
b671c2067a ("bpf: Retire the struct_ops map kvalue->refcnt.")
Remove it.
Suggested-by: Martin KaFai Lau <martin.lau@linux.dev>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20241112145849.3436772-2-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
For struct_ops progs, whether a particular prog uses private stack
depends on prog->aux->priv_stack_requested setting before actual
insn-level verification for that prog. One particular implementation
is to piggyback on struct_ops->check_member(). The next patch has
an example for this. The struct_ops->check_member() sets
prog->aux->priv_stack_requested to be true which enables private stack
usage.
The struct_ops prog follows the same rule as kprobe/tracing progs after
function bpf_enable_priv_stack(). For example, even a struct_ops prog
requests private stack, it could still use normal kernel stack if
the stack size is small (< 64 bytes).
Similar to tracing progs, nested same cpu same prog run will be skipped.
A field (recursion_detected()) is added to bpf_prog_aux structure.
If bpf_prog->aux->recursion_detected is implemented by the struct_ops
subsystem and nested same cpu/prog happens, the function will be
triggered to report an error, collect related info, etc.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20241112163933.2224962-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
If private stack is used by any subprog, set that subprog
prog->aux->jits_use_priv_stack to be true so later jit can allocate
private stack for that subprog properly.
Also set env->prog->aux->jits_use_priv_stack to be true if
any subprog uses private stack. This is a use case for a
single main prog (no subprogs) to use private stack, and
also a use case for later struct-ops progs where
env->prog->aux->jits_use_priv_stack will enable recursion
check if any subprog uses private stack.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20241112163912.2224007-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Private stack will be allocated with percpu allocator in jit time.
To avoid complexity at runtime, only one copy of private stack is
available per cpu per prog. So runtime recursion check is necessary
to avoid stack corruption.
Current private stack only supports kprobe/perf_event/tp/raw_tp
which has recursion check in the kernel, and prog types that use
bpf trampoline recursion check. For trampoline related prog types,
currently only tracing progs have recursion checking.
To avoid complexity, all async_cb subprogs use normal kernel stack
including those subprogs used by both main prog subtree and async_cb
subtree. Any prog having tail call also uses kernel stack.
To avoid jit penalty with private stack support, a subprog stack
size threshold is set such that only if the stack size is no less
than the threshold, private stack is supported. The current threshold
is 64 bytes. This avoids jit penality if the stack usage is small.
A useless 'continue' is also removed from a loop in func
check_max_stack_depth().
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20241112163907.2223839-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Logic to prevent callbacks from acquiring new references for the program
(i.e. leaving acquired references), and releasing caller references
(i.e. those acquired in parent frames) was introduced in commit
9d9d00ac29 ("bpf: Fix reference state management for synchronous callbacks").
This was necessary because back then, the verifier simulated each
callback once (that could potentially be executed N times, where N can
be zero). This meant that callbacks that left lingering resources or
cleared caller resources could do it more than once, operating on
undefined state or leaking memory.
With the fixes to callback verification in commit
ab5cfac139 ("bpf: verify callbacks as if they are called unknown number of times"),
all of this extra logic is no longer necessary. Hence, drop it as part
of this commit.
Cc: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241109231430.2475236-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
When bpf_spin_lock was introduced originally, there was deliberation on
whether to use an array of lock IDs, but since bpf_spin_lock is limited
to holding a single lock at any given time, we've been using a single ID
to identify the held lock.
In preparation for introducing spin locks that can be taken multiple
times, introduce support for acquiring multiple lock IDs. For this
purpose, reuse the acquired_refs array and store both lock and pointer
references. We tag the entry with REF_TYPE_PTR or REF_TYPE_LOCK to
disambiguate and find the relevant entry. The ptr field is used to track
the map_ptr or btf (for bpf_obj_new allocations) to ensure locks can be
matched with protected fields within the same "allocation", i.e.
bpf_obj_new object or map value.
The struct active_lock is changed to an int as the state is part of the
acquired_refs array, and we only need active_lock as a cheap way of
detecting lock presence.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241109231430.2475236-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
For htab of maps, when the map is removed from the htab, it may hold the
last reference of the map. bpf_map_fd_put_ptr() will invoke
bpf_map_free_id() to free the id of the removed map element. However,
bpf_map_fd_put_ptr() is invoked while holding a bucket lock
(raw_spin_lock_t), and bpf_map_free_id() attempts to acquire map_idr_lock
(spinlock_t), triggering the following lockdep warning:
=============================
[ BUG: Invalid wait context ]
6.11.0-rc4+ #49 Not tainted
-----------------------------
test_maps/4881 is trying to lock:
ffffffff84884578 (map_idr_lock){+...}-{3:3}, at: bpf_map_free_id.part.0+0x21/0x70
other info that might help us debug this:
context-{5:5}
2 locks held by test_maps/4881:
#0: ffffffff846caf60 (rcu_read_lock){....}-{1:3}, at: bpf_fd_htab_map_update_elem+0xf9/0x270
#1: ffff888149ced148 (&htab->lockdep_key#2){....}-{2:2}, at: htab_map_update_elem+0x178/0xa80
stack backtrace:
CPU: 0 UID: 0 PID: 4881 Comm: test_maps Not tainted 6.11.0-rc4+ #49
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ...
Call Trace:
<TASK>
dump_stack_lvl+0x6e/0xb0
dump_stack+0x10/0x20
__lock_acquire+0x73e/0x36c0
lock_acquire+0x182/0x450
_raw_spin_lock_irqsave+0x43/0x70
bpf_map_free_id.part.0+0x21/0x70
bpf_map_put+0xcf/0x110
bpf_map_fd_put_ptr+0x9a/0xb0
free_htab_elem+0x69/0xe0
htab_map_update_elem+0x50f/0xa80
bpf_fd_htab_map_update_elem+0x131/0x270
htab_map_update_elem+0x50f/0xa80
bpf_fd_htab_map_update_elem+0x131/0x270
bpf_map_update_value+0x266/0x380
__sys_bpf+0x21bb/0x36b0
__x64_sys_bpf+0x45/0x60
x64_sys_call+0x1b2a/0x20d0
do_syscall_64+0x5d/0x100
entry_SYSCALL_64_after_hwframe+0x76/0x7e
One way to fix the lockdep warning is using raw_spinlock_t for
map_idr_lock as well. However, bpf_map_alloc_id() invokes
idr_alloc_cyclic() after acquiring map_idr_lock, it will trigger a
similar lockdep warning because the slab's lock (s->cpu_slab->lock) is
still a spinlock.
Instead of changing map_idr_lock's type, fix the issue by invoking
htab_put_fd_value() after htab_unlock_bucket(). However, only deferring
the invocation of htab_put_fd_value() is not enough, because the old map
pointers in htab of maps can not be saved during batched deletion.
Therefore, also defer the invocation of free_htab_elem(), so these
to-be-freed elements could be linked together similar to lru map.
There are four callers for ->map_fd_put_ptr:
(1) alloc_htab_elem() (through htab_put_fd_value())
It invokes ->map_fd_put_ptr() under a raw_spinlock_t. The invocation of
htab_put_fd_value() can not simply move after htab_unlock_bucket(),
because the old element has already been stashed in htab->extra_elems.
It may be reused immediately after htab_unlock_bucket() and the
invocation of htab_put_fd_value() after htab_unlock_bucket() may release
the newly-added element incorrectly. Therefore, saving the map pointer
of the old element for htab of maps before unlocking the bucket and
releasing the map_ptr after unlock. Beside the map pointer in the old
element, should do the same thing for the special fields in the old
element as well.
(2) free_htab_elem() (through htab_put_fd_value())
Its caller includes __htab_map_lookup_and_delete_elem(),
htab_map_delete_elem() and __htab_map_lookup_and_delete_batch().
For htab_map_delete_elem(), simply invoke free_htab_elem() after
htab_unlock_bucket(). For __htab_map_lookup_and_delete_batch(), just
like lru map, linking the to-be-freed element into node_to_free list
and invoking free_htab_elem() for these element after unlock. It is safe
to reuse batch_flink as the link for node_to_free, because these
elements have been removed from the hash llist.
Because htab of maps doesn't support lookup_and_delete operation,
__htab_map_lookup_and_delete_elem() doesn't have the problem, so kept
it as is.
(3) fd_htab_map_free()
It invokes ->map_fd_put_ptr without raw_spinlock_t.
(4) bpf_fd_htab_map_update_elem()
It invokes ->map_fd_put_ptr without raw_spinlock_t.
After moving free_htab_elem() outside htab bucket lock scope, using
pcpu_freelist_push() instead of __pcpu_freelist_push() to disable
the irq before freeing elements, and protecting the invocations of
bpf_mem_cache_free() with migrate_{disable|enable} pair.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241106063542.357743-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Adding support to attach BPF program for entry and return probe
of the same function. This is common use case which at the moment
requires to create two uprobe multi links.
Adding new BPF_TRACE_UPROBE_SESSION attach type that instructs
kernel to attach single link program to both entry and exit probe.
It's possible to control execution of the BPF program on return
probe simply by returning zero or non zero from the entry BPF
program execution to execute or not the BPF program on return
probe respectively.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241108134544.480660-4-jolsa@kernel.org
The kprobe session program can return only 0 or 1,
instruct verifier to check for that.
Fixes: 535a3692ba ("bpf: Add support for kprobe session attach")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241108134544.480660-2-jolsa@kernel.org
Arguments to a raw tracepoint are tagged as trusted, which carries the
semantics that the pointer will be non-NULL. However, in certain cases,
a raw tracepoint argument may end up being NULL. More context about this
issue is available in [0].
Thus, there is a discrepancy between the reality, that raw_tp arguments
can actually be NULL, and the verifier's knowledge, that they are never
NULL, causing explicit NULL checks to be deleted, and accesses to such
pointers potentially crashing the kernel.
To fix this, mark raw_tp arguments as PTR_MAYBE_NULL, and then special
case the dereference and pointer arithmetic to permit it, and allow
passing them into helpers/kfuncs; these exceptions are made for raw_tp
programs only. Ensure that we don't do this when ref_obj_id > 0, as in
that case this is an acquired object and doesn't need such adjustment.
The reason we do mask_raw_tp_trusted_reg logic is because other will
recheck in places whether the register is a trusted_reg, and then
consider our register as untrusted when detecting the presence of the
PTR_MAYBE_NULL flag.
To allow safe dereference, we enable PROBE_MEM marking when we see loads
into trusted pointers with PTR_MAYBE_NULL.
While trusted raw_tp arguments can also be passed into helpers or kfuncs
where such broken assumption may cause issues, a future patch set will
tackle their case separately, as PTR_TO_BTF_ID (without PTR_TRUSTED) can
already be passed into helpers and causes similar problems. Thus, they
are left alone for now.
It is possible that these checks also permit passing non-raw_tp args
that are trusted PTR_TO_BTF_ID with null marking. In such a case,
allowing dereference when pointer is NULL expands allowed behavior, so
won't regress existing programs, and the case of passing these into
helpers is the same as above and will be dealt with later.
Also update the failure case in tp_btf_nullable selftest to capture the
new behavior, as the verifier will no longer cause an error when
directly dereference a raw tracepoint argument marked as __nullable.
[0]: https://lore.kernel.org/bpf/ZrCZS6nisraEqehw@jlelli-thinkpadt14gen4.remote.csb
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Reported-by: Juri Lelli <juri.lelli@redhat.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Fixes: 3f00c52393 ("bpf: Allow trusted pointers to be passed to KF_TRUSTED_ARGS kfuncs")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241104171959.2938862-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
There are similar checks for covering locks, references, RCU read
sections and preempt_disable sections in 3 places in the verifer, i.e.
for tail calls, bpf_ld_[abs, ind], and exit path (for BPF_EXIT and
bpf_throw). Unify all of these into a common check_resource_leak
function to avoid code duplication.
Also update the error strings in selftests to the new ones in the same
change to ensure clean bisection.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241103225940.1408302-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
There are three situations when a program logically exits and transfers
control to the kernel or another program: bpf_throw, BPF_EXIT, and tail
calls. The former two check for any lingering locks and references, but
tail calls currently do not. Expand the checks to check for spin locks,
RCU read sections and preempt disabled sections.
Spin locks are indirectly preventing tail calls as function calls are
disallowed, but the checks for preemption and RCU are more relaxed,
hence ensure tail calls are prevented in their presence.
Fixes: 9bb00b2895 ("bpf: Add kfunc bpf_rcu_read_lock/unlock()")
Fixes: fc7566ad0a ("bpf: Introduce bpf_preempt_[disable,enable] kfuncs")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241103225940.1408302-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Now that kernel supports sleepable tracepoints, the fact that
bpf_probe_unregister() is asynchronous, i.e., that it doesn't wait for
any in-flight tracepoints to conclude before returning, we now need to
delay BPF raw tp link's deallocation and bpf_prog_put() of its
underlying BPF program (regardless of program's own sleepable semantics)
until after full RCU Tasks Trace GP. With that GP over, we'll have
a guarantee that no tracepoint can reach BPF link and thus its BPF program.
We use newly added tracepoint_is_faultable() check to know when this RCU
Tasks Trace GP is necessary and utilize BPF link's own sleepable flag
passed through bpf_link_init_sleepable() initializer.
Link: https://lore.kernel.org/20241101181754.782341-3-andrii@kernel.org
Tested-by: Jordan Rife <jrife@google.com>
Reported-by: Jordan Rife <jrife@google.com>
Fixes: a363d27cdb ("tracing: Allow system call tracepoints to handle page faults")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
BPF link's lifecycle protection scheme depends on both BPF hook and BPF
program. If *either* of those require RCU Tasks Trace GP, then we need
to go through a chain of GPs before putting BPF program refcount and
deallocating BPF link memory.
This patch adds bpf_link-specific sleepable flag, which can be set to
true even if underlying BPF program is not sleepable itself. If either
link->sleepable or link->prog->sleepable is true, we'll go through
a chain of RCU Tasks Trace GP and RCU GP before putting BPF program and
freeing memory.
This will be used to protect BPF link for sleepable (faultable) raw
tracepoints in the next patch.
Link: https://lore.kernel.org/20241101181754.782341-2-andrii@kernel.org
Tested-by: Jordan Rife <jrife@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
In general, BPF link's underlying BPF program should be considered to be
reachable through attach hook -> link -> prog chain, and, pessimistically,
we have to assume that as long as link's memory is not safe to free,
attach hook's code might hold a pointer to BPF program and use it.
As such, it's not (generally) correct to put link's program early before
waiting for RCU GPs to go through. More eager bpf_prog_put() that we
currently do is mostly correct due to BPF program's release code doing
similar RCU GP waiting, but as will be shown in the following patches,
BPF program can be non-sleepable (and, thus, reliant on only "classic"
RCU GP), while BPF link's attach hook can have sleepable semantics and
needs to be protected by RCU Tasks Trace, and for such cases BPF link
has to go through RCU Tasks Trace + "classic" RCU GPs before being
deallocated. And so, if we put BPF program early, we might free BPF
program before we free BPF link, leading to use-after-free situation.
So, this patch defers bpf_prog_put() until we are ready to perform
bpf_link's deallocation. At worst, this delays BPF program freeing by
one extra RCU GP, but that seems completely acceptable. Alternatively,
we'd need more elaborate ways to determine BPF hook, BPF link, and BPF
program lifetimes, and how they relate to each other, which seems like
an unnecessary complication.
Note, for most BPF links we still will perform eager bpf_prog_put() and
link dealloc, so for those BPF links there are no observable changes
whatsoever. Only BPF links that use deferred dealloc might notice
slightly delayed freeing of BPF programs.
Also, to reduce code and logic duplication, extract program put + link
dealloc logic into bpf_link_dealloc() helper.
Link: https://lore.kernel.org/20241101181754.782341-1-andrii@kernel.org
Tested-by: Jordan Rife <jrife@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add a new open coded iterator for kmem_cache which can be called from a
BPF program like below. It doesn't take any argument and traverses all
kmem_cache entries.
struct kmem_cache *pos;
bpf_for_each(kmem_cache, pos) {
...
}
As it needs to grab slab_mutex, it should be called from sleepable BPF
programs only.
Also update the existing iterator code to use the open coded version
internally as suggested by Andrii.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20241030222819.1800667-1-namhyung@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Fix BPF verifier to force a checkpoint when the program's jump
history becomes too long (Eduard Zingerman)
- Add several fixes to the BPF bits iterator addressing issues
like memory leaks and overflow problems (Hou Tao)
- Fix an out-of-bounds write in trie_get_next_key (Byeonguk Jeong)
- Fix BPF test infra's LIVE_FRAME frame update after a page has
been recycled (Toke Høiland-Jørgensen)
- Fix BPF verifier and undo the 40-bytes extra stack space for
bpf_fastcall patterns due to various bugs (Eduard Zingerman)
- Fix a BPF sockmap race condition which could trigger a NULL
pointer dereference in sock_map_link_update_prog (Cong Wang)
- Fix tcp_bpf_recvmsg_parser to retrieve seq_copied from tcp_sk
under the socket lock (Jiayuan Chen)
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Pull bpf fixes from Daniel Borkmann:
- Fix BPF verifier to force a checkpoint when the program's jump
history becomes too long (Eduard Zingerman)
- Add several fixes to the BPF bits iterator addressing issues like
memory leaks and overflow problems (Hou Tao)
- Fix an out-of-bounds write in trie_get_next_key (Byeonguk Jeong)
- Fix BPF test infra's LIVE_FRAME frame update after a page has been
recycled (Toke Høiland-Jørgensen)
- Fix BPF verifier and undo the 40-bytes extra stack space for
bpf_fastcall patterns due to various bugs (Eduard Zingerman)
- Fix a BPF sockmap race condition which could trigger a NULL pointer
dereference in sock_map_link_update_prog (Cong Wang)
- Fix tcp_bpf_recvmsg_parser to retrieve seq_copied from tcp_sk under
the socket lock (Jiayuan Chen)
* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
bpf, test_run: Fix LIVE_FRAME frame update after a page has been recycled
selftests/bpf: Add three test cases for bits_iter
bpf: Use __u64 to save the bits in bits iterator
bpf: Check the validity of nr_words in bpf_iter_bits_new()
bpf: Add bpf_mem_alloc_check_size() helper
bpf: Free dynamically allocated bits in bpf_iter_bits_destroy()
bpf: disallow 40-bytes extra stack for bpf_fastcall patterns
selftests/bpf: Add test for trie_get_next_key()
bpf: Fix out-of-bounds write in trie_get_next_key()
selftests/bpf: Test with a very short loop
bpf: Force checkpoint when jmp history is too long
bpf: fix filed access without lock
sock_map: fix a NULL pointer dereference in sock_map_link_update_prog()
On 32-bit hosts (e.g., arm32), when a bpf program passes a u64 to
bpf_iter_bits_new(), bpf_iter_bits_new() will use bits_copy to store the
content of the u64. However, bits_copy is only 4 bytes, leading to stack
corruption.
The straightforward solution would be to replace u64 with unsigned long
in bpf_iter_bits_new(). However, this introduces confusion and problems
for 32-bit hosts because the size of ulong in bpf program is 8 bytes,
but it is treated as 4-bytes after passed to bpf_iter_bits_new().
Fix it by changing the type of both bits and bit_count from unsigned
long to u64. However, the change is not enough. The main reason is that
bpf_iter_bits_next() uses find_next_bit() to find the next bit and the
pointer passed to find_next_bit() is an unsigned long pointer instead
of a u64 pointer. For 32-bit little-endian host, it is fine but it is
not the case for 32-bit big-endian host. Because under 32-bit big-endian
host, the first iterated unsigned long will be the bits 32-63 of the u64
instead of the expected bits 0-31. Therefore, in addition to changing
the type, swap the two unsigned longs within the u64 for 32-bit
big-endian host.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241030100516.3633640-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Check the validity of nr_words in bpf_iter_bits_new(). Without this
check, when multiplication overflow occurs for nr_bits (e.g., when
nr_words = 0x0400-0001, nr_bits becomes 64), stack corruption may occur
due to bpf_probe_read_kernel_common(..., nr_bytes = 0x2000-0008).
Fix it by limiting the maximum value of nr_words to 511. The value is
derived from the current implementation of BPF memory allocator. To
ensure compatibility if the BPF memory allocator's size limitation
changes in the future, use the helper bpf_mem_alloc_check_size() to
check whether nr_bytes is too larger. And return -E2BIG instead of
-ENOMEM for oversized nr_bytes.
Fixes: 4665415975 ("bpf: Add bits iterator")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241030100516.3633640-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introduce bpf_mem_alloc_check_size() to check whether the allocation
size exceeds the limitation for the kmalloc-equivalent allocator. The
upper limit for percpu allocation is LLIST_NODE_SZ bytes larger than
non-percpu allocation, so a percpu argument is added to the helper.
The helper will be used in the following patch to check whether the size
parameter passed to bpf_mem_alloc() is too big.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241030100516.3633640-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_iter_bits_destroy() uses "kit->nr_bits <= 64" to check whether the
bits are dynamically allocated. However, the check is incorrect and may
cause a kmemleak as shown below:
unreferenced object 0xffff88812628c8c0 (size 32):
comm "swapper/0", pid 1, jiffies 4294727320
hex dump (first 32 bytes):
b0 c1 55 f5 81 88 ff ff f0 f0 f0 f0 f0 f0 f0 f0 ..U...........
f0 f0 f0 f0 f0 f0 f0 f0 00 00 00 00 00 00 00 00 ..............
backtrace (crc 781e32cc):
[<00000000c452b4ab>] kmemleak_alloc+0x4b/0x80
[<0000000004e09f80>] __kmalloc_node_noprof+0x480/0x5c0
[<00000000597124d6>] __alloc.isra.0+0x89/0xb0
[<000000004ebfffcd>] alloc_bulk+0x2af/0x720
[<00000000d9c10145>] prefill_mem_cache+0x7f/0xb0
[<00000000ff9738ff>] bpf_mem_alloc_init+0x3e2/0x610
[<000000008b616eac>] bpf_global_ma_init+0x19/0x30
[<00000000fc473efc>] do_one_initcall+0xd3/0x3c0
[<00000000ec81498c>] kernel_init_freeable+0x66a/0x940
[<00000000b119f72f>] kernel_init+0x20/0x160
[<00000000f11ac9a7>] ret_from_fork+0x3c/0x70
[<0000000004671da4>] ret_from_fork_asm+0x1a/0x30
That is because nr_bits will be set as zero in bpf_iter_bits_next()
after all bits have been iterated.
Fix the issue by setting kit->bit to kit->nr_bits instead of setting
kit->nr_bits to zero when the iteration completes in
bpf_iter_bits_next(). In addition, use "!nr_bits || bits >= nr_bits" to
check whether the iteration is complete and still use "nr_bits > 64" to
indicate whether bits are dynamically allocated. The "!nr_bits" check is
necessary because bpf_iter_bits_new() may fail before setting
kit->nr_bits, and this condition will stop the iteration early instead
of accessing the zeroed or freed kit->bits.
Considering the initial value of kit->bits is -1 and the type of
kit->nr_bits is unsigned int, change the type of kit->nr_bits to int.
The potential overflow problem will be handled in the following patch.
Fixes: 4665415975 ("bpf: Add bits iterator")
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241030100516.3633640-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- cgroup_bpf_release_fn() could saturate system_wq with
cgrp->bpf.release_work which can then form a circular dependency leading
to deadlocks. Fix by using a dedicated workqueue. The system_wq's max
concurrency limit is being increased separately.
- Fix theoretical off-by-one bug when enforcing max cgroup hierarchy depth.
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Merge tag 'cgroup-for-6.12-rc5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
- cgroup_bpf_release_fn() could saturate system_wq with
cgrp->bpf.release_work which can then form a circular dependency
leading to deadlocks. Fix by using a dedicated workqueue. The
system_wq's max concurrency limit is being increased separately.
- Fix theoretical off-by-one bug when enforcing max cgroup hierarchy
depth
* tag 'cgroup-for-6.12-rc5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Fix potential overflow issue when checking max_depth
cgroup/bpf: use a dedicated workqueue for cgroup bpf destruction
trie_get_next_key() allocates a node stack with size trie->max_prefixlen,
while it writes (trie->max_prefixlen + 1) nodes to the stack when it has
full paths from the root to leaves. For example, consider a trie with
max_prefixlen is 8, and the nodes with key 0x00/0, 0x00/1, 0x00/2, ...
0x00/8 inserted. Subsequent calls to trie_get_next_key with _key with
.prefixlen = 8 make 9 nodes be written on the node stack with size 8.
Fixes: b471f2f1de ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map")
Signed-off-by: Byeonguk Jeong <jungbu2855@gmail.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Tested-by: Hou Tao <houtao1@huawei.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/Zxx384ZfdlFYnz6J@localhost.localdomain
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A specifically crafted program might trick verifier into growing very
long jump history within a single bpf_verifier_state instance.
Very long jump history makes mark_chain_precision() unreasonably slow,
especially in case if verifier processes a loop.
Mitigate this by forcing new state in is_state_visited() in case if
current state's jump history is too long.
Use same constant as in `skip_inf_loop_check`, but multiply it by
arbitrarily chosen value 2 to account for jump history containing not
only information about jumps, but also information about stack access.
For an example of problematic program consider the code below,
w/o this patch the example is processed by verifier for ~15 minutes,
before failing to allocate big-enough chunk for jmp_history.
0: r7 = *(u16 *)(r1 +0);"
1: r7 += 0x1ab064b9;"
2: if r7 & 0x702000 goto 1b;
3: r7 &= 0x1ee60e;"
4: r7 += r1;"
5: if r7 s> 0x37d2 goto +0;"
6: r0 = 0;"
7: exit;"
Perf profiling shows that most of the time is spent in
mark_chain_precision() ~95%.
The easiest way to explain why this program causes problems is to
apply the following patch:
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 0c216e71cec7..4b4823961abe 100644
\--- a/include/linux/bpf.h
\+++ b/include/linux/bpf.h
\@@ -1926,7 +1926,7 @@ struct bpf_array {
};
};
-#define BPF_COMPLEXITY_LIMIT_INSNS 1000000 /* yes. 1M insns */
+#define BPF_COMPLEXITY_LIMIT_INSNS 256 /* yes. 1M insns */
#define MAX_TAIL_CALL_CNT 33
/* Maximum number of loops for bpf_loop and bpf_iter_num.
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f514247ba8ba..75e88be3bb3e 100644
\--- a/kernel/bpf/verifier.c
\+++ b/kernel/bpf/verifier.c
\@@ -18024,8 +18024,13 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
skip_inf_loop_check:
if (!force_new_state &&
env->jmps_processed - env->prev_jmps_processed < 20 &&
- env->insn_processed - env->prev_insn_processed < 100)
+ env->insn_processed - env->prev_insn_processed < 100) {
+ verbose(env, "is_state_visited: suppressing checkpoint at %d, %d jmps processed, cur->jmp_history_cnt is %d\n",
+ env->insn_idx,
+ env->jmps_processed - env->prev_jmps_processed,
+ cur->jmp_history_cnt);
add_new_state = false;
+ }
goto miss;
}
/* If sl->state is a part of a loop and this loop's entry is a part of
\@@ -18142,6 +18147,9 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
if (!add_new_state)
return 0;
+ verbose(env, "is_state_visited: new checkpoint at %d, resetting env->jmps_processed\n",
+ env->insn_idx);
+
/* There were no equivalent states, remember the current one.
* Technically the current state is not proven to be safe yet,
* but it will either reach outer most bpf_exit (which means it's safe)
And observe verification log:
...
is_state_visited: new checkpoint at 5, resetting env->jmps_processed
5: R1=ctx() R7=ctx(...)
5: (65) if r7 s> 0x37d2 goto pc+0 ; R7=ctx(...)
6: (b7) r0 = 0 ; R0_w=0
7: (95) exit
from 5 to 6: R1=ctx() R7=ctx(...) R10=fp0
6: R1=ctx() R7=ctx(...) R10=fp0
6: (b7) r0 = 0 ; R0_w=0
7: (95) exit
is_state_visited: suppressing checkpoint at 1, 3 jmps processed, cur->jmp_history_cnt is 74
from 2 to 1: R1=ctx() R7_w=scalar(...) R10=fp0
1: R1=ctx() R7_w=scalar(...) R10=fp0
1: (07) r7 += 447767737
is_state_visited: suppressing checkpoint at 2, 3 jmps processed, cur->jmp_history_cnt is 75
2: R7_w=scalar(...)
2: (45) if r7 & 0x702000 goto pc-2
... mark_precise 152 steps for r7 ...
2: R7_w=scalar(...)
is_state_visited: suppressing checkpoint at 1, 4 jmps processed, cur->jmp_history_cnt is 75
1: (07) r7 += 447767737
is_state_visited: suppressing checkpoint at 2, 4 jmps processed, cur->jmp_history_cnt is 76
2: R7_w=scalar(...)
2: (45) if r7 & 0x702000 goto pc-2
...
BPF program is too large. Processed 257 insn
The log output shows that checkpoint at label (1) is never created,
because it is suppressed by `skip_inf_loop_check` logic:
a. When 'if' at (2) is processed it pushes a state with insn_idx (1)
onto stack and proceeds to (3);
b. At (5) checkpoint is created, and this resets
env->{jmps,insns}_processed.
c. Verification proceeds and reaches `exit`;
d. State saved at step (a) is popped from stack and is_state_visited()
considers if checkpoint needs to be added, but because
env->{jmps,insns}_processed had been just reset at step (b)
the `skip_inf_loop_check` logic forces `add_new_state` to false.
e. Verifier proceeds with current state, which slowly accumulates
more and more entries in the jump history.
The accumulation of entries in the jump history is a problem because
of two factors:
- it eventually exhausts memory available for kmalloc() allocation;
- mark_chain_precision() traverses the jump history of a state,
meaning that if `r7` is marked precise, verifier would iterate
ever growing jump history until parent state boundary is reached.
(note: the log also shows a REG INVARIANTS VIOLATION warning
upon jset processing, but that's another bug to fix).
With this patch applied, the example above is rejected by verifier
under 1s of time, reaching 1M instructions limit.
The program is a simplified reproducer from syzbot report.
Previous discussion could be found at [1].
The patch does not cause any changes in verification performance,
when tested on selftests from veristat.cfg and cilium programs taken
from [2].
[1] https://lore.kernel.org/bpf/20241009021254.2805446-1-eddyz87@gmail.com/
[2] https://github.com/anakryiko/cilium
Changelog:
- v1 -> v2:
- moved patch to bpf tree;
- moved force_new_state variable initialization after declaration and
shortened the comment.
v1: https://lore.kernel.org/bpf/20241018020307.1766906-1-eddyz87@gmail.com/
Fixes: 2589726d12 ("bpf: introduce bounded loops")
Reported-by: syzbot+7e46cdef14bf496a3ab4@syzkaller.appspotmail.com
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20241029172641.1042523-1-eddyz87@gmail.com
Closes: https://lore.kernel.org/bpf/670429f6.050a0220.49194.0517.GAE@google.com/
This patch adds uptr support in the map_value of the task local storage.
struct map_value {
struct user_data __uptr *uptr;
};
struct {
__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
__type(key, int);
__type(value, struct value_type);
} datamap SEC(".maps");
A new bpf_obj_pin_uptrs() is added to pin the user page and
also stores the kernel address back to the uptr for the
bpf prog to use later. It currently does not support
the uptr pointing to a user struct across two pages.
It also excludes PageHighMem support to keep it simple.
As of now, the 32bit bpf jit is missing other more crucial bpf
features. For example, many important bpf features depend on
bpf kfunc now but so far only one arch (x86-32) supports it
which was added by me as an example when kfunc was first
introduced to bpf.
The uptr can only be stored to the task local storage by the
syscall update_elem. Meaning the uptr will not be considered
if it is provided by the bpf prog through
bpf_task_storage_get(BPF_LOCAL_STORAGE_GET_F_CREATE).
This is enforced by only calling
bpf_local_storage_update(swap_uptrs==true) in
bpf_pid_task_storage_update_elem. Everywhere else will
have swap_uptrs==false.
This will pump down to bpf_selem_alloc(swap_uptrs==true). It is
the only case that bpf_selem_alloc() will take the uptr value when
updating the newly allocated selem. bpf_obj_swap_uptrs() is added
to swap the uptr between the SDATA(selem)->data and the user provided
map_value in "void *value". bpf_obj_swap_uptrs() makes the
SDATA(selem)->data takes the ownership of the uptr and the user space
provided map_value will have NULL in the uptr.
The bpf_obj_unpin_uptrs() is called after map->ops->map_update_elem()
returning error. If the map->ops->map_update_elem has reached
a state that the local storage has taken the uptr ownership,
the bpf_obj_unpin_uptrs() will be a no op because the uptr
is NULL. A "__"bpf_obj_unpin_uptrs is added to make this
error path unpin easier such that it does not have to check
the map->record is NULL or not.
BPF_F_LOCK is not supported when the map_value has uptr.
This can be revisited later if there is a use case. A similar
swap_uptrs idea can be considered.
The final bit is to do unpin_user_page in the bpf_obj_free_fields().
The earlier patch has ensured that the bpf_obj_free_fields() has
gone through the rcu gp when needed.
Cc: linux-mm@kvack.org
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Link: https://lore.kernel.org/r/20241023234759.860539-7-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A later patch will enable the uptr usage in the task_local_storage map.
This will require the unpin_user_page() to be done after the rcu
task trace gp for the cases that the uptr may still be used by
a bpf prog. The bpf_obj_free_fields() will be the one doing
unpin_user_page(), so this patch is to postpone calling
bpf_obj_free_fields() to the rcu callback.
The bpf_obj_free_fields() is only required to be done in
the rcu callback when bpf->bpf_ma==true and reuse_now==false.
bpf->bpf_ma==true case is because uptr will only be enabled
in task storage which has already been moved to bpf_mem_alloc.
The bpf->bpf_ma==false case can be supported in the future
also if there is a need.
reuse_now==false when the selem (aka storage) is deleted
by bpf prog (bpf_task_storage_delete) or by syscall delete_elem().
In both cases, bpf_obj_free_fields() needs to wait for
rcu gp.
A few words on reuse_now==true. reuse_now==true when the
storage's owner (i.e. the task_struct) is destructing or the map
itself is doing map_free(). In both cases, no bpf prog should
have a hold on the selem and its uptrs, so there is no need to
postpone bpf_obj_free_fields(). reuse_now==true should be the
common case for local storage usage where the storage exists
throughout the lifetime of its owner (task_struct).
The bpf_obj_free_fields() needs to use the map->record. Doing
bpf_obj_free_fields() in a rcu callback will require the
bpf_local_storage_map_free() to wait for rcu_barrier. An optimization
could be only waiting for rcu_barrier when the map has uptr in
its map_value. This will require either yet another rcu callback
function or adding a bool in the selem to flag if the SDATA(selem)->smap
is still valid. This patch chooses to keep it simple and wait for
rcu_barrier for maps that use bpf_mem_alloc.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241023234759.860539-6-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In a later patch, bpf_selem_free() will call unpin_user_page()
through bpf_obj_free_fields(). unpin_user_page() may take spin_lock.
However, some bpf_selem_free() call paths have held a raw_spin_lock.
Like this:
raw_spin_lock_irqsave()
bpf_selem_unlink_storage_nolock()
bpf_selem_free()
unpin_user_page()
spin_lock()
To avoid spinlock nested in raw_spinlock, bpf_selem_free() should be
done after releasing the raw_spinlock. The "bool reuse_now" arg is
replaced with "struct hlist_head *free_selem_list" in
bpf_selem_unlink_storage_nolock(). The bpf_selem_unlink_storage_nolock()
will append the to-be-free selem at the free_selem_list. The caller of
bpf_selem_unlink_storage_nolock() will need to call the new
bpf_selem_free_list(free_selem_list, reuse_now) to free the selem
after releasing the raw_spinlock.
Note that the selem->snode cannot be reused for linking to
the free_selem_list because the selem->snode is protected by the
raw_spinlock that we want to avoid holding. A new
"struct hlist_node free_node;" is union-ized with
the rcu_head. Only the first one successfully
hlist_del_init_rcu(&selem->snode) will be able
to use the free_node. After succeeding hlist_del_init_rcu(&selem->snode),
the free_node and rcu_head usage is serialized such that they
can share the 16 bytes in a union.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241023234759.860539-5-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In a later patch, the task local storage will only accept uptr
from the syscall update_elem and will not accept uptr from
the bpf prog. The reason is the bpf prog does not have a way
to provide a valid user space address.
bpf_local_storage_update() and bpf_selem_alloc() are used by
both bpf prog bpf_task_storage_get(BPF_LOCAL_STORAGE_GET_F_CREATE)
and bpf syscall update_elem. "bool swap_uptrs" arg is added
to bpf_local_storage_update() and bpf_selem_alloc() to tell if
it is called by the bpf prog or by the bpf syscall. When
swap_uptrs==true, it is called by the syscall.
The arg is named (swap_)uptrs because the later patch will swap
the uptrs between the newly allocated selem and the user space
provided map_value. It will make error handling easier in case
map->ops->map_update_elem() fails and the caller can decide
if it needs to unpin the uptr in the user space provided
map_value or the bpf_local_storage_update() has already
taken the uptr ownership and will take care of unpinning it also.
Only swap_uptrs==false is passed now. The logic to handle
the true case will be added in a later patch.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241023234759.860539-4-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch adds BPF_UPTR support to the verifier. Not that only the
map_value will support the "__uptr" type tag.
This patch enforces only BPF_LDX is allowed to the value of an uptr.
After BPF_LDX, it will mark the dst_reg as PTR_TO_MEM | PTR_MAYBE_NULL
with size deduced from the field.kptr.btf_id. This will make the
dst_reg pointed memory to be readable and writable as scalar.
There is a redundant "val_reg = reg_state(env, value_regno);" statement
in the check_map_kptr_access(). This patch takes this chance to remove
it also.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241023234759.860539-3-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch introduces the "__uptr" type tag to BTF. It is to define
a pointer pointing to the user space memory. This patch adds BTF
logic to pass the "__uptr" type tag.
btf_find_kptr() is reused for the "__uptr" tag. The "__uptr" will only
be supported in the map_value of the task storage map. However,
btf_parse_struct_meta() also uses btf_find_kptr() but it is not
interested in "__uptr". This patch adds a "field_mask" argument
to btf_find_kptr() which will return BTF_FIELD_IGNORE if the
caller is not interested in a “__uptr” field.
btf_parse_kptr() is also reused to parse the uptr.
The btf_check_and_fixup_fields() is changed to do extra
checks on the uptr to ensure that its struct size is not larger
than PAGE_SIZE. It is not clear how a uptr pointing to a CO-RE
supported kernel struct will be used, so it is also not allowed now.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241023234759.860539-2-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
If a newly-added link type doesn't invoke BPF_LINK_TYPE(), accessing
bpf_link_type_strs[link->type] may result in an out-of-bounds access.
To spot such missed invocations early in the future, checking the
validity of link->type in bpf_link_show_fdinfo() and emitting a warning
when such invocations are missed.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241024013558.1135167-3-houtao@huaweicloud.com
We need `goto next_insn;` at the end of patching instead of `continue;`.
It currently works by accident by making verifier re-process patched
instructions.
Reported-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Fixes: 314a53623c ("bpf: inline bpf_get_branch_snapshot() helper")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20241023161916.2896274-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Lonial reported an issue in the BPF verifier where check_mem_size_reg()
has the following code:
if (!tnum_is_const(reg->var_off))
/* For unprivileged variable accesses, disable raw
* mode so that the program is required to
* initialize all the memory that the helper could
* just partially fill up.
*/
meta = NULL;
This means that writes are not checked when the register containing the
size of the passed buffer has not a fixed size. Through this bug, a BPF
program can write to a map which is marked as read-only, for example,
.rodata global maps.
The problem is that MEM_UNINIT's initial meaning that "the passed buffer
to the BPF helper does not need to be initialized" which was added back
in commit 435faee1aa ("bpf, verifier: add ARG_PTR_TO_RAW_STACK type")
got overloaded over time with "the passed buffer is being written to".
The problem however is that checks such as the above which were added later
via 06c1c04972 ("bpf: allow helpers access to variable memory") set meta
to NULL in order force the user to always initialize the passed buffer to
the helper. Due to the current double meaning of MEM_UNINIT, this bypasses
verifier write checks to the memory (not boundary checks though) and only
assumes the latter memory is read instead.
Fix this by reverting MEM_UNINIT back to its original meaning, and having
MEM_WRITE as an annotation to BPF helpers in order to then trigger the
BPF verifier checks for writing to memory.
Some notes: check_arg_pair_ok() ensures that for ARG_CONST_SIZE{,_OR_ZERO}
we can access fn->arg_type[arg - 1] since it must contain a preceding
ARG_PTR_TO_MEM. For check_mem_reg() the meta argument can be removed
altogether since we do check both BPF_READ and BPF_WRITE. Same for the
equivalent check_kfunc_mem_size_reg().
Fixes: 7b3552d3f9 ("bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access")
Fixes: 97e6d7dab1 ("bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access")
Fixes: 15baa55ff5 ("bpf/verifier: allow all functions to read user provided context")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241021152809.33343-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a MEM_WRITE attribute for BPF helper functions which can be used in
bpf_func_proto to annotate an argument type in order to let the verifier
know that the helper writes into the memory passed as an argument. In
the past MEM_UNINIT has been (ab)used for this function, but the latter
merely tells the verifier that the passed memory can be uninitialized.
There have been bugs with overloading the latter but aside from that
there are also cases where the passed memory is read + written which
currently cannot be expressed, see also 4b3786a6c5 ("bpf: Zero former
ARG_PTR_TO_{LONG,INT} args in case of error").
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241021152809.33343-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In bpf_parse_param(), keep the value of param->string intact so it can
be freed later. Otherwise, the kmalloc area pointed to by param->string
will be leaked as shown below:
unreferenced object 0xffff888118c46d20 (size 8):
comm "new_name", pid 12109, jiffies 4295580214
hex dump (first 8 bytes):
61 6e 79 00 38 c9 5c 7e any.8.\~
backtrace (crc e1b7f876):
[<00000000c6848ac7>] kmemleak_alloc+0x4b/0x80
[<00000000de9f7d00>] __kmalloc_node_track_caller_noprof+0x36e/0x4a0
[<000000003e29b886>] memdup_user+0x32/0xa0
[<0000000007248326>] strndup_user+0x46/0x60
[<0000000035b3dd29>] __x64_sys_fsconfig+0x368/0x3d0
[<0000000018657927>] x64_sys_call+0xff/0x9f0
[<00000000c0cabc95>] do_syscall_64+0x3b/0xc0
[<000000002f331597>] entry_SYSCALL_64_after_hwframe+0x4b/0x53
Fixes: 6c1752e0b6 ("bpf: Support symbolic BPF FS delegation mount options")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20241022130133.3798232-1-houtao@huaweicloud.com
Implement bpf_send_signal_task kfunc that is similar to
bpf_send_signal_thread and bpf_send_signal helpers but can be used to
send signals to other threads and processes. It also supports sending a
cookie with the signal similar to sigqueue().
If the receiving process establishes a handler for the signal using the
SA_SIGINFO flag to sigaction(), then it can obtain this cookie via the
si_value field of the siginfo_t structure passed as the second argument
to the handler.
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241016084136.10305-2-puranjay@kernel.org
- Fix BPF verifier to not affect subreg_def marks in its range
propagation, from Eduard Zingerman.
- Fix a truncation bug in the BPF verifier's handling of
coerce_reg_to_size_sx, from Dimitar Kanaliev.
- Fix the BPF verifier's delta propagation between linked
registers under 32-bit addition, from Daniel Borkmann.
- Fix a NULL pointer dereference in BPF devmap due to missing
rxq information, from Florian Kauer.
- Fix a memory leak in bpf_core_apply, from Jiri Olsa.
- Fix an UBSAN-reported array-index-out-of-bounds in BTF
parsing for arrays of nested structs, from Hou Tao.
- Fix build ID fetching where memory areas backing the file
were created with memfd_secret, from Andrii Nakryiko.
- Fix BPF task iterator tid filtering which was incorrectly
using pid instead of tid, from Jordan Rome.
- Several fixes for BPF sockmap and BPF sockhash redirection
in combination with vsocks, from Michal Luczaj.
- Fix riscv BPF JIT and make BPF_CMPXCHG fully ordered,
from Andrea Parri.
- Fix riscv BPF JIT under CONFIG_CFI_CLANG to prevent the
possibility of an infinite BPF tailcall, from Pu Lehui.
- Fix a build warning from resolve_btfids that bpf_lsm_key_free
cannot be resolved, from Thomas Weißschuh.
- Fix a bug in kfunc BTF caching for modules where the wrong
BTF object was returned, from Toke Høiland-Jørgensen.
- Fix a BPF selftest compilation error in cgroup-related tests
with musl libc, from Tony Ambardar.
- Several fixes to BPF link info dumps to fill missing fields,
from Tyrone Wu.
- Add BPF selftests for kfuncs from multiple modules, checking
that the correct kfuncs are called, from Simon Sundberg.
- Ensure that internal and user-facing bpf_redirect flags
don't overlap, also from Toke Høiland-Jørgensen.
- Switch to use kvzmalloc to allocate BPF verifier environment,
from Rik van Riel.
- Use raw_spinlock_t in BPF ringbuf to fix a sleep in atomic
splat under RT, from Wander Lairson Costa.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Pull bpf fixes from Daniel Borkmann:
- Fix BPF verifier to not affect subreg_def marks in its range
propagation (Eduard Zingerman)
- Fix a truncation bug in the BPF verifier's handling of
coerce_reg_to_size_sx (Dimitar Kanaliev)
- Fix the BPF verifier's delta propagation between linked registers
under 32-bit addition (Daniel Borkmann)
- Fix a NULL pointer dereference in BPF devmap due to missing rxq
information (Florian Kauer)
- Fix a memory leak in bpf_core_apply (Jiri Olsa)
- Fix an UBSAN-reported array-index-out-of-bounds in BTF parsing for
arrays of nested structs (Hou Tao)
- Fix build ID fetching where memory areas backing the file were
created with memfd_secret (Andrii Nakryiko)
- Fix BPF task iterator tid filtering which was incorrectly using pid
instead of tid (Jordan Rome)
- Several fixes for BPF sockmap and BPF sockhash redirection in
combination with vsocks (Michal Luczaj)
- Fix riscv BPF JIT and make BPF_CMPXCHG fully ordered (Andrea Parri)
- Fix riscv BPF JIT under CONFIG_CFI_CLANG to prevent the possibility
of an infinite BPF tailcall (Pu Lehui)
- Fix a build warning from resolve_btfids that bpf_lsm_key_free cannot
be resolved (Thomas Weißschuh)
- Fix a bug in kfunc BTF caching for modules where the wrong BTF object
was returned (Toke Høiland-Jørgensen)
- Fix a BPF selftest compilation error in cgroup-related tests with
musl libc (Tony Ambardar)
- Several fixes to BPF link info dumps to fill missing fields (Tyrone
Wu)
- Add BPF selftests for kfuncs from multiple modules, checking that the
correct kfuncs are called (Simon Sundberg)
- Ensure that internal and user-facing bpf_redirect flags don't overlap
(Toke Høiland-Jørgensen)
- Switch to use kvzmalloc to allocate BPF verifier environment (Rik van
Riel)
- Use raw_spinlock_t in BPF ringbuf to fix a sleep in atomic splat
under RT (Wander Lairson Costa)
* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: (38 commits)
lib/buildid: Handle memfd_secret() files in build_id_parse()
selftests/bpf: Add test case for delta propagation
bpf: Fix print_reg_state's constant scalar dump
bpf: Fix incorrect delta propagation between linked registers
bpf: Properly test iter/task tid filtering
bpf: Fix iter/task tid filtering
riscv, bpf: Make BPF_CMPXCHG fully ordered
bpf, vsock: Drop static vsock_bpf_prot initialization
vsock: Update msg_count on read_skb()
vsock: Update rx_bytes on read_skb()
bpf, sockmap: SK_DROP on attempted redirects of unsupported af_vsock
selftests/bpf: Add asserts for netfilter link info
bpf: Fix link info netfilter flags to populate defrag flag
selftests/bpf: Add test for sign extension in coerce_subreg_to_size_sx()
selftests/bpf: Add test for truncation after sign extension in coerce_reg_to_size_sx()
bpf: Fix truncation bug in coerce_reg_to_size_sx()
selftests/bpf: Assert link info uprobe_multi count & path_size if unset
bpf: Fix unpopulated path_size when uprobe_multi fields unset
selftests/bpf: Fix cross-compiling urandom_read
selftests/bpf: Add test for kfunc module order
...
print_reg_state() should not consider adding reg->off to reg->var_off.value
when dumping scalars. Scalars can be produced with reg->off != 0 through
BPF_ADD_CONST, and thus as-is this can skew the register log dump.
Fixes: 98d7ca374b ("bpf: Track delta between "linked" registers.")
Reported-by: Nathaniel Theis <nathaniel.theis@nccgroup.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241016134913.32249-2-daniel@iogearbox.net
Nathaniel reported a bug in the linked scalar delta tracking, which can lead
to accepting a program with OOB access. The specific code is related to the
sync_linked_regs() function and the BPF_ADD_CONST flag, which signifies a
constant offset between two scalar registers tracked by the same register id.
The verifier attempts to track "similar" scalars in order to propagate bounds
information learned about one scalar to others. For instance, if r1 and r2
are known to contain the same value, then upon encountering 'if (r1 != 0x1234)
goto xyz', not only does it know that r1 is equal to 0x1234 on the path where
that conditional jump is not taken, it also knows that r2 is.
Additionally, with env->bpf_capable set, the verifier will track scalars
which should be a constant delta apart (if r1 is known to be one greater than
r2, then if r1 is known to be equal to 0x1234, r2 must be equal to 0x1233.)
The code path for the latter in adjust_reg_min_max_vals() is reached when
processing both 32 and 64-bit addition operations. While adjust_reg_min_max_vals()
knows whether dst_reg was produced by a 32 or a 64-bit addition (based on the
alu32 bool), the only information saved in dst_reg is the id of the source
register (reg->id, or'ed by BPF_ADD_CONST) and the value of the constant
offset (reg->off).
Later, the function sync_linked_regs() will attempt to use this information
to propagate bounds information from one register (known_reg) to others,
meaning, for all R in linked_regs, it copies known_reg range (and possibly
adjusting delta) into R for the case of R->id == known_reg->id.
For the delta adjustment, meaning, matching reg->id with BPF_ADD_CONST, the
verifier adjusts the register as reg = known_reg; reg += delta where delta
is computed as (s32)reg->off - (s32)known_reg->off and placed as a scalar
into a fake_reg to then simulate the addition of reg += fake_reg. This is
only correct, however, if the value in reg was created by a 64-bit addition.
When reg contains the result of a 32-bit addition operation, its upper 32
bits will always be zero. sync_linked_regs() on the other hand, may cause
the verifier to believe that the addition between fake_reg and reg overflows
into those upper bits. For example, if reg was generated by adding the
constant 1 to known_reg using a 32-bit alu operation, then reg->off is 1
and known_reg->off is 0. If known_reg is known to be the constant 0xFFFFFFFF,
sync_linked_regs() will tell the verifier that reg is equal to the constant
0x100000000. This is incorrect as the actual value of reg will be 0, as the
32-bit addition will wrap around.
Example:
0: (b7) r0 = 0; R0_w=0
1: (18) r1 = 0x80000001; R1_w=0x80000001
3: (37) r1 /= 1; R1_w=scalar()
4: (bf) r2 = r1; R1_w=scalar(id=1) R2_w=scalar(id=1)
5: (bf) r4 = r1; R1_w=scalar(id=1) R4_w=scalar(id=1)
6: (04) w2 += 2147483647; R2_w=scalar(id=1+2147483647,smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))
7: (04) w4 += 0 ; R4_w=scalar(id=1+0,smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))
8: (15) if r2 == 0x0 goto pc+1
10: R0=0 R1=0xffffffff80000001 R2=0x7fffffff R4=0xffffffff80000001 R10=fp0
What can be seen here is that r1 is copied to r2 and r4, such that {r1,r2,r4}.id
are all the same which later lets sync_linked_regs() to be invoked. Then, in
a next step constants are added with alu32 to r2 and r4, setting their ->off,
as well as id |= BPF_ADD_CONST. Next, the conditional will bind r2 and
propagate ranges to its linked registers. The verifier now believes the upper
32 bits of r4 are r4=0xffffffff80000001, while actually r4=r1=0x80000001.
One approach for a simple fix suitable also for stable is to limit the constant
delta tracking to only 64-bit alu addition. If necessary at some later point,
BPF_ADD_CONST could be split into BPF_ADD_CONST64 and BPF_ADD_CONST32 to avoid
mixing the two under the tradeoff to further complicate sync_linked_regs().
However, none of the added tests from dedf56d775 ("selftests/bpf: Add tests
for add_const") make this necessary at this point, meaning, BPF CI also passes
with just limiting tracking to 64-bit alu addition.
Fixes: 98d7ca374b ("bpf: Track delta between "linked" registers.")
Reported-by: Nathaniel Theis <nathaniel.theis@nccgroup.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20241016134913.32249-1-daniel@iogearbox.net
In userspace, you can add a tid filter by setting
the "task.tid" field for "bpf_iter_link_info".
However, `get_pid_task` when called for the
`BPF_TASK_ITER_TID` type should have been using
`PIDTYPE_PID` (tid) instead of `PIDTYPE_TGID` (pid).
Fixes: f0d74c4da1 ("bpf: Parameterize task iterators.")
Signed-off-by: Jordan Rome <linux@jordanrome.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241016210048.1213935-1-linux@jordanrome.com
There is a potential infinite loop issue that can occur when using a
combination of tail calls and freplace.
In an upcoming selftest, the attach target for entry_freplace of
tailcall_freplace.c is subprog_tc of tc_bpf2bpf.c, while the tail call in
entry_freplace leads to entry_tc. This results in an infinite loop:
entry_tc -> subprog_tc -> entry_freplace --tailcall-> entry_tc.
The problem arises because the tail_call_cnt in entry_freplace resets to
zero each time entry_freplace is executed, causing the tail call mechanism
to never terminate, eventually leading to a kernel panic.
To fix this issue, the solution is twofold:
1. Prevent updating a program extended by an freplace program to a
prog_array map.
2. Prevent extending a program that is already part of a prog_array map
with an freplace program.
This ensures that:
* If a program or its subprogram has been extended by an freplace program,
it can no longer be updated to a prog_array map.
* If a program has been added to a prog_array map, neither it nor its
subprograms can be extended by an freplace program.
Moreover, an extension program should not be tailcalled. As such, return
-EINVAL if the program has a type of BPF_PROG_TYPE_EXT when adding it to a
prog_array map.
Additionally, fix a minor code style issue by replacing eight spaces with a
tab for proper formatting.
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20241015150207.70264-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_task_from_pid() that currently exists looks up the
struct task_struct corresponding to the pid in the root pid
namespace (init_pid_ns).
This patch adds bpf_task_from_vpid() which looks up the
struct task_struct corresponding to vpid in the pid namespace
of the current process.
This is useful for getting information about other processes
in the same pid namespace.
Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Link: https://lore.kernel.org/r/AM6PR03MB5848E50DA58F79CDE65433C399442@AM6PR03MB5848.eurprd03.prod.outlook.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The bpf_get_kmem_cache() is to get a slab cache information from a
virtual address like virt_to_cache(). If the address is a pointer
to a slab object, it'd return a valid kmem_cache pointer, otherwise
NULL is returned.
It doesn't grab a reference count of the kmem_cache so the caller is
responsible to manage the access. The returned point is marked as
PTR_UNTRUSTED.
The intended use case for now is to symbolize locks in slab objects
from the lock contention tracepoints.
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev> (mm/*)
Acked-by: Vlastimil Babka <vbabka@suse.cz> #mm/slab
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20241010232505.1339892-3-namhyung@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
coerce_reg_to_size_sx() updates the register state after a sign-extension
operation. However, there's a bug in the assignment order of the unsigned
min/max values, leading to incorrect truncation:
0: (85) call bpf_get_prandom_u32#7 ; R0_w=scalar()
1: (57) r0 &= 1 ; R0_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1,var_off=(0x0; 0x1))
2: (07) r0 += 254 ; R0_w=scalar(smin=umin=smin32=umin32=254,smax=umax=smax32=umax32=255,var_off=(0xfe; 0x1))
3: (bf) r0 = (s8)r0 ; R0_w=scalar(smin=smin32=-2,smax=smax32=-1,umin=umin32=0xfffffffe,umax=0xffffffff,var_off=(0xfffffffffffffffe; 0x1))
In the current implementation, the unsigned 32-bit min/max values
(u32_min_value and u32_max_value) are assigned directly from the 64-bit
signed min/max values (s64_min and s64_max):
reg->umin_value = reg->u32_min_value = s64_min;
reg->umax_value = reg->u32_max_value = s64_max;
Due to the chain assigmnent, this is equivalent to:
reg->u32_min_value = s64_min; // Unintended truncation
reg->umin_value = reg->u32_min_value;
reg->u32_max_value = s64_max; // Unintended truncation
reg->umax_value = reg->u32_max_value;
Fixes: 1f9a1ea821 ("bpf: Support new sign-extension load insns")
Reported-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Reported-by: Zac Ecob <zacecob@protonmail.com>
Signed-off-by: Dimitar Kanaliev <dimitar.kanaliev@siteground.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Reviewed-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20241014121155.92887-2-dimitar.kanaliev@siteground.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The new "kmem_cache" iterator will traverse the list of slab caches
and call attached BPF programs for each entry. It should check the
argument (ctx.s) if it's NULL before using it.
Now the iteration grabs the slab_mutex only if it traverse the list and
releases the mutex when it runs the BPF program. The kmem_cache entry
is protected by a refcount during the execution.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz> #slab
Link: https://lore.kernel.org/r/20241010232505.1339892-2-namhyung@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The verifier contains a cache for looking up module BTF objects when
calling kfuncs defined in modules. This cache uses a 'struct
bpf_kfunc_btf_tab', which contains a sorted list of BTF objects that
were already seen in the current verifier run, and the BTF objects are
looked up by the offset stored in the relocated call instruction using
bsearch().
The first time a given offset is seen, the module BTF is loaded from the
file descriptor passed in by libbpf, and stored into the cache. However,
there's a bug in the code storing the new entry: it stores a pointer to
the new cache entry, then calls sort() to keep the cache sorted for the
next lookup using bsearch(), and then returns the entry that was just
stored through the stored pointer. However, because sort() modifies the
list of entries in place *by value*, the stored pointer may no longer
point to the right entry, in which case the wrong BTF object will be
returned.
The end result of this is an intermittent bug where, if a BPF program
calls two functions with the same signature in two different modules,
the function from the wrong module may sometimes end up being called.
Whether this happens depends on the order of the calls in the BPF
program (as that affects whether sort() reorders the array of BTF
objects), making it especially hard to track down. Simon, credited as
reporter below, spent significant effort analysing and creating a
reproducer for this issue. The reproducer is added as a selftest in a
subsequent patch.
The fix is straight forward: simply don't use the stored pointer after
calling sort(). Since we already have an on-stack pointer to the BTF
object itself at the point where the function return, just use that, and
populate it from the cache entry in the branch where the lookup
succeeds.
Fixes: 2357672c54 ("bpf: Introduce BPF support for kernel module function calls")
Reported-by: Simon Sundberg <simon.sundberg@kau.se>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20241010-fix-kfunc-btf-caching-for-modules-v2-1-745af6c1af98@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Previously when retrieving `bpf_link_info.perf_event` for
kprobe/uprobe/tracepoint, the `name_len` field was not populated by the
kernel, leaving it to reflect the value initially set by the user. This
behavior was inconsistent with how other input/output string buffer
fields function (e.g. `raw_tracepoint.tp_name_len`).
This patch fills `name_len` with the actual size of the string name.
Fixes: 1b715e1b0e ("bpf: Support ->fill_link_info for perf_event")
Signed-off-by: Tyrone Wu <wudevelops@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20241008164312.46269-1-wudevelops@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The kzmalloc call in bpf_check can fail when memory is very fragmented,
which in turn can lead to an OOM kill.
Use kvzmalloc to fall back to vmalloc when memory is too fragmented to
allocate an order 3 sized bpf verifier environment.
Admittedly this is not a very common case, and only happens on systems
where memory has already been squeezed close to the limit, but this does
not seem like much of a hot path, and it's a simple enough fix.
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Link: https://lore.kernel.org/r/20241008170735.16766766@imladris.surriel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When trying to repeat the btf fields for array of nested struct, it
doesn't check the remaining info_cnt. The following splat will be
reported when the value of ret * nelems is greater than BTF_FIELDS_MAX:
------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in ../kernel/bpf/btf.c:3951:49
index 11 is out of range for type 'btf_field_info [11]'
CPU: 6 UID: 0 PID: 411 Comm: test_progs ...... 6.11.0-rc4+ #1
Tainted: [O]=OOT_MODULE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ...
Call Trace:
<TASK>
dump_stack_lvl+0x57/0x70
dump_stack+0x10/0x20
ubsan_epilogue+0x9/0x40
__ubsan_handle_out_of_bounds+0x6f/0x80
? kallsyms_lookup_name+0x48/0xb0
btf_parse_fields+0x992/0xce0
map_create+0x591/0x770
__sys_bpf+0x229/0x2410
__x64_sys_bpf+0x1f/0x30
x64_sys_call+0x199/0x9f0
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7fea56f2cc5d
......
</TASK>
---[ end trace ]---
Fix it by checking the remaining info_cnt in btf_repeat_fields() before
repeating the btf fields.
Fixes: 64e8ee8148 ("bpf: look into the types of the fields of a struct type recursively.")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241008071114.3718177-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The sysctl core is moving to allow "struct ctl_table" in read-only memory.
As a preparation for that all functions handling "struct ctl_table" need
to be able to work with "const struct ctl_table".
As __cgroup_bpf_run_filter_sysctl() does not modify its table, it can be
adapted trivially.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
The key_free LSM hook has been removed.
Remove the corresponding BPF hook.
Avoid warnings during the build:
BTFIDS vmlinux
WARN: resolve_btfids: unresolved symbol bpf_lsm_key_free
Fixes: 5f8d28f6d7 ("lsm: infrastructure management of the key security blob")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20241005-lsm-key_free-v1-1-42ea801dbd63@weissschuh.net
A hung_task problem shown below was found:
INFO: task kworker/0:0:8 blocked for more than 327 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Workqueue: events cgroup_bpf_release
Call Trace:
<TASK>
__schedule+0x5a2/0x2050
? find_held_lock+0x33/0x100
? wq_worker_sleeping+0x9e/0xe0
schedule+0x9f/0x180
schedule_preempt_disabled+0x25/0x50
__mutex_lock+0x512/0x740
? cgroup_bpf_release+0x1e/0x4d0
? cgroup_bpf_release+0xcf/0x4d0
? process_scheduled_works+0x161/0x8a0
? cgroup_bpf_release+0x1e/0x4d0
? mutex_lock_nested+0x2b/0x40
? __pfx_delay_tsc+0x10/0x10
mutex_lock_nested+0x2b/0x40
cgroup_bpf_release+0xcf/0x4d0
? process_scheduled_works+0x161/0x8a0
? trace_event_raw_event_workqueue_execute_start+0x64/0xd0
? process_scheduled_works+0x161/0x8a0
process_scheduled_works+0x23a/0x8a0
worker_thread+0x231/0x5b0
? __pfx_worker_thread+0x10/0x10
kthread+0x14d/0x1c0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x59/0x70
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1b/0x30
</TASK>
This issue can be reproduced by the following pressuse test:
1. A large number of cpuset cgroups are deleted.
2. Set cpu on and off repeatly.
3. Set watchdog_thresh repeatly.
The scripts can be obtained at LINK mentioned above the signature.
The reason for this issue is cgroup_mutex and cpu_hotplug_lock are
acquired in different tasks, which may lead to deadlock.
It can lead to a deadlock through the following steps:
1. A large number of cpusets are deleted asynchronously, which puts a
large number of cgroup_bpf_release works into system_wq. The max_active
of system_wq is WQ_DFL_ACTIVE(256). Consequently, all active works are
cgroup_bpf_release works, and many cgroup_bpf_release works will be put
into inactive queue. As illustrated in the diagram, there are 256 (in
the acvtive queue) + n (in the inactive queue) works.
2. Setting watchdog_thresh will hold cpu_hotplug_lock.read and put
smp_call_on_cpu work into system_wq. However step 1 has already filled
system_wq, 'sscs.work' is put into inactive queue. 'sscs.work' has
to wait until the works that were put into the inacvtive queue earlier
have executed (n cgroup_bpf_release), so it will be blocked for a while.
3. Cpu offline requires cpu_hotplug_lock.write, which is blocked by step 2.
4. Cpusets that were deleted at step 1 put cgroup_release works into
cgroup_destroy_wq. They are competing to get cgroup_mutex all the time.
When cgroup_metux is acqured by work at css_killed_work_fn, it will
call cpuset_css_offline, which needs to acqure cpu_hotplug_lock.read.
However, cpuset_css_offline will be blocked for step 3.
5. At this moment, there are 256 works in active queue that are
cgroup_bpf_release, they are attempting to acquire cgroup_mutex, and as
a result, all of them are blocked. Consequently, sscs.work can not be
executed. Ultimately, this situation leads to four processes being
blocked, forming a deadlock.
system_wq(step1) WatchDog(step2) cpu offline(step3) cgroup_destroy_wq(step4)
...
2000+ cgroups deleted asyn
256 actives + n inactives
__lockup_detector_reconfigure
P(cpu_hotplug_lock.read)
put sscs.work into system_wq
256 + n + 1(sscs.work)
sscs.work wait to be executed
warting sscs.work finish
percpu_down_write
P(cpu_hotplug_lock.write)
...blocking...
css_killed_work_fn
P(cgroup_mutex)
cpuset_css_offline
P(cpu_hotplug_lock.read)
...blocking...
256 cgroup_bpf_release
mutex_lock(&cgroup_mutex);
..blocking...
To fix the problem, place cgroup_bpf_release works on a dedicated
workqueue which can break the loop and solve the problem. System wqs are
for misc things which shouldn't create a large number of concurrent work
items. If something is going to generate >WQ_DFL_ACTIVE(256) concurrent
work items, it should use its own dedicated workqueue.
Fixes: 4bfc0bb2c6 ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself")
Cc: stable@vger.kernel.org # v5.3+
Link: https://lore.kernel.org/cgroups/e90c32d2-2a85-4f28-9154-09c7d320cb60@huawei.com/T/#t
Tested-by: Vishal Chourasia <vishalc@linux.ibm.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
some of those used to be needed, some had been cargo-culted for
no reason...
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Once upon a time, predecessors of those used to do file lookup
without bumping a refcount, provided that caller held rcu_read_lock()
across the lookup and whatever it wanted to read from the struct
file found. When struct file allocation switched to SLAB_TYPESAFE_BY_RCU,
that stopped being feasible and these primitives started to bump the
file refcount for lookup result, requiring the caller to call fput()
afterwards.
But that turned them pointless - e.g.
rcu_read_lock();
file = lookup_fdget_rcu(fd);
rcu_read_unlock();
is equivalent to
file = fget_raw(fd);
and all callers of lookup_fdget_rcu() are of that form. Similarly,
task_lookup_fdget_rcu() calls can be replaced with calling fget_task().
task_lookup_next_fdget_rcu() doesn't have direct counterparts, but
its callers would be happier if we replaced it with an analogue that
deals with RCU internally.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
In order to allow pahole add btf_decl_tag("bpf_fastcall") for kfuncs
supporting bpf_fastcall, mark such functions with KF_FASTCALL in
id_set8 objects.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240916091712.2929279-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A kfree() call is always used at the end of this function implementation.
Thus specify such a function call only once instead of duplicating it
in a previous if branch.
This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/08987123-668c-40f3-a8ee-c3038d94f069@web.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
struct btf_kind_operations are not modified in BTF.
Constifying this structures moves some data to a read-only section,
so increase overall security, especially when the structure holds
some function pointers.
On a x86_64, with allmodconfig:
Before:
======
text data bss dec hex filename
184320 7091 548 191959 2edd7 kernel/bpf/btf.o
After:
=====
text data bss dec hex filename
184896 6515 548 191959 2edd7 kernel/bpf/btf.o
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/9192ab72b2e9c66aefd6520f359a20297186327f.1726417289.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
asm/unaligned.h is always an include of asm-generic/unaligned.h;
might as well move that thing to linux/unaligned.h and include
that - there's nothing arch-specific in that header.
auto-generated by the following:
for i in `git grep -l -w asm/unaligned.h`; do
sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i
done
for i in `git grep -l -w asm-generic/unaligned.h`; do
sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i
done
git mv include/asm-generic/unaligned.h include/linux/unaligned.h
git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h
sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild
sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h
Range propagation must not affect subreg_def marks, otherwise the
following example is rewritten by verifier incorrectly when
BPF_F_TEST_RND_HI32 flag is set:
0: call bpf_ktime_get_ns call bpf_ktime_get_ns
1: r0 &= 0x7fffffff after verifier r0 &= 0x7fffffff
2: w1 = w0 rewrites w1 = w0
3: if w0 < 10 goto +0 --------------> r11 = 0x2f5674a6 (r)
4: r1 >>= 32 r11 <<= 32 (r)
5: r0 = r1 r1 |= r11 (r)
6: exit; if w0 < 0xa goto pc+0
r1 >>= 32
r0 = r1
exit
(or zero extension of w1 at (2) is missing for architectures that
require zero extension for upper register half).
The following happens w/o this patch:
- r0 is marked as not a subreg at (0);
- w1 is marked as subreg at (2);
- w1 subreg_def is overridden at (3) by copy_register_state();
- w1 is read at (5) but mark_insn_zext() does not mark (2)
for zero extension, because w1 subreg_def is not set;
- because of BPF_F_TEST_RND_HI32 flag verifier inserts random
value for hi32 bits of (2) (marked (r));
- this random value is read at (5).
Fixes: 75748837b7 ("bpf: Propagate scalar ranges through register assignments.")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://lore.kernel.org/bpf/7e2aa30a62d740db182c170fdd8f81c596df280d.camel@gmail.com
Link: https://lore.kernel.org/bpf/20240924210844.1758441-1-eddyz87@gmail.com
no_llseek had been defined to NULL two years ago, in commit 868941b144
("fs: remove no_llseek")
To quote that commit,
At -rc1 we'll need do a mechanical removal of no_llseek -
git grep -l -w no_llseek | grep -v porting.rst | while read i; do
sed -i '/\<no_llseek\>/d' $i
done
would do it.
Unfortunately, that hadn't been done. Linus, could you do that now, so
that we could finally put that thing to rest? All instances are of the
form
.llseek = no_llseek,
so it's obviously safe.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The function __bpf_ringbuf_reserve is invoked from a tracepoint, which
disables preemption. Using spinlock_t in this context can lead to a
"sleep in atomic" warning in the RT variant. This issue is illustrated
in the example below:
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 556208, name: test_progs
preempt_count: 1, expected: 0
RCU nest depth: 1, expected: 1
INFO: lockdep is turned off.
Preemption disabled at:
[<ffffd33a5c88ea44>] migrate_enable+0xc0/0x39c
CPU: 7 PID: 556208 Comm: test_progs Tainted: G
Hardware name: Qualcomm SA8775P Ride (DT)
Call trace:
dump_backtrace+0xac/0x130
show_stack+0x1c/0x30
dump_stack_lvl+0xac/0xe8
dump_stack+0x18/0x30
__might_resched+0x3bc/0x4fc
rt_spin_lock+0x8c/0x1a4
__bpf_ringbuf_reserve+0xc4/0x254
bpf_ringbuf_reserve_dynptr+0x5c/0xdc
bpf_prog_ac3d15160d62622a_test_read_write+0x104/0x238
trace_call_bpf+0x238/0x774
perf_call_bpf_enter.isra.0+0x104/0x194
perf_syscall_enter+0x2f8/0x510
trace_sys_enter+0x39c/0x564
syscall_trace_enter+0x220/0x3c0
do_el0_svc+0x138/0x1dc
el0_svc+0x54/0x130
el0t_64_sync_handler+0x134/0x150
el0t_64_sync+0x17c/0x180
Switch the spinlock to raw_spinlock_t to avoid this error.
Fixes: 457f44363a ("bpf: Implement BPF ring buffer and verifier support for it")
Reported-by: Brian Grech <bgrech@redhat.com>
Signed-off-by: Wander Lairson Costa <wander.lairson@gmail.com>
Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240920190700.617253-1-wander@redhat.com
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Merge tag 'bpf-next-6.12-struct-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf 'struct fd' updates from Alexei Starovoitov:
"This includes struct_fd BPF changes from Al and Andrii"
* tag 'bpf-next-6.12-struct-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next:
bpf: convert bpf_token_create() to CLASS(fd, ...)
security,bpf: constify struct path in bpf_token_create() LSM hook
bpf: more trivial fdget() conversions
bpf: trivial conversions for fdget()
bpf: switch maps to CLASS(fd, ...)
bpf: factor out fetching bpf_map from FD and adding it to used_maps list
bpf: switch fdget_raw() uses to CLASS(fd_raw, ...)
bpf: convert __bpf_prog_get() to CLASS(fd, ...)
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Merge tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull 'struct fd' updates from Al Viro:
"Just the 'struct fd' layout change, with conversion to accessor
helpers"
* tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
add struct fd constructors, get rid of __to_fd()
struct fd: representation change
introduce fd_file(), convert all accessors to it.
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Merge tag 'bpf-next-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf updates from Alexei Starovoitov:
- Introduce '__attribute__((bpf_fastcall))' for helpers and kfuncs with
corresponding support in LLVM.
It is similar to existing 'no_caller_saved_registers' attribute in
GCC/LLVM with a provision for backward compatibility. It allows
compilers generate more efficient BPF code assuming the verifier or
JITs will inline or partially inline a helper/kfunc with such
attribute. bpf_cast_to_kern_ctx, bpf_rdonly_cast,
bpf_get_smp_processor_id are the first set of such helpers.
- Harden and extend ELF build ID parsing logic.
When called from sleepable context the relevants parts of ELF file
will be read to find and fetch .note.gnu.build-id information. Also
harden the logic to avoid TOCTOU, overflow, out-of-bounds problems.
- Improvements and fixes for sched-ext:
- Allow passing BPF iterators as kfunc arguments
- Make the pointer returned from iter_next method trusted
- Fix x86 JIT convergence issue due to growing/shrinking conditional
jumps in variable length encoding
- BPF_LSM related:
- Introduce few VFS kfuncs and consolidate them in
fs/bpf_fs_kfuncs.c
- Enforce correct range of return values from certain LSM hooks
- Disallow attaching to other LSM hooks
- Prerequisite work for upcoming Qdisc in BPF:
- Allow kptrs in program provided structs
- Support for gen_epilogue in verifier_ops
- Important fixes:
- Fix uprobe multi pid filter check
- Fix bpf_strtol and bpf_strtoul helpers
- Track equal scalars history on per-instruction level
- Fix tailcall hierarchy on x86 and arm64
- Fix signed division overflow to prevent INT_MIN/-1 trap on x86
- Fix get kernel stack in BPF progs attached to tracepoint:syscall
- Selftests:
- Add uprobe bench/stress tool
- Generate file dependencies to drastically improve re-build time
- Match JIT-ed and BPF asm with __xlated/__jited keywords
- Convert older tests to test_progs framework
- Add support for RISC-V
- Few fixes when BPF programs are compiled with GCC-BPF backend
(support for GCC-BPF in BPF CI is ongoing in parallel)
- Add traffic monitor
- Enable cross compile and musl libc
* tag 'bpf-next-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (260 commits)
btf: require pahole 1.21+ for DEBUG_INFO_BTF with default DWARF version
btf: move pahole check in scripts/link-vmlinux.sh to lib/Kconfig.debug
btf: remove redundant CONFIG_BPF test in scripts/link-vmlinux.sh
bpf: Call the missed kfree() when there is no special field in btf
bpf: Call the missed btf_record_free() when map creation fails
selftests/bpf: Add a test case to write mtu result into .rodata
selftests/bpf: Add a test case to write strtol result into .rodata
selftests/bpf: Rename ARG_PTR_TO_LONG test description
selftests/bpf: Fix ARG_PTR_TO_LONG {half-,}uninitialized test
bpf: Zero former ARG_PTR_TO_{LONG,INT} args in case of error
bpf: Improve check_raw_mode_ok test for MEM_UNINIT-tagged types
bpf: Fix helper writes to read-only maps
bpf: Remove truncation test in bpf_strtol and bpf_strtoul helpers
bpf: Fix bpf_strtol and bpf_strtoul helpers for 32bit
selftests/bpf: Add tests for sdiv/smod overflow cases
bpf: Fix a sdiv overflow issue
libbpf: Add bpf_object__token_fd accessor
docs/bpf: Add missing BPF program types to docs
docs/bpf: Add constant values for linkages
bpf: Use fake pt_regs when doing bpf syscall tracepoint tracing
...
Call the missed kfree() in btf_parse_struct_metas() when there is no
special field in btf, otherwise will get the following kmemleak report:
unreferenced object 0xffff888101033620 (size 8):
comm "test_progs", pid 604, jiffies 4295127011
......
backtrace (crc e77dc444):
[<00000000186f90f3>] kmemleak_alloc+0x4b/0x80
[<00000000ac8e9c4d>] __kmalloc_cache_noprof+0x2a1/0x310
[<00000000d99d68d6>] btf_new_fd+0x72d/0xe90
[<00000000f010b7f8>] __sys_bpf+0xec3/0x2410
[<00000000e077ed6f>] __x64_sys_bpf+0x1f/0x30
[<00000000a12f9e55>] x64_sys_call+0x199/0x9f0
[<00000000f3029ea6>] do_syscall_64+0x3b/0xc0
[<000000005640913a>] entry_SYSCALL_64_after_hwframe+0x4b/0x53
Fixes: 7a851ecb18 ("bpf: Search for kptrs in prog BTF structs")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20240912012845.3458483-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When security_bpf_map_create() in map_create() fails, map_create() will
call btf_put() and ->map_free() callback to free the map. It doesn't
free the btf_record of map value, so add the missed btf_record_free()
when map creation fails.
However btf_record_free() needs to be called after ->map_free() just
like bpf_map_free_deferred() did, because ->map_free() may use the
btf_record to free the special fields in preallocated map value. So
factor out bpf_map_free() helper to free the map, btf_record, and btf
orderly and use the helper in both map_create() and
bpf_map_free_deferred().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20240912012845.3458483-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
For all non-tracing helpers which formerly had ARG_PTR_TO_{LONG,INT} as input
arguments, zero the value for the case of an error as otherwise it could leak
memory. For tracing, it is not needed given CAP_PERFMON can already read all
kernel memory anyway hence bpf_get_func_arg() and bpf_get_func_ret() is skipped
in here.
Also, the MTU helpers mtu_len pointer value is being written but also read.
Technically, the MEM_UNINIT should not be there in order to always force init.
Removing MEM_UNINIT needs more verifier rework though: MEM_UNINIT right now
implies two things actually: i) write into memory, ii) memory does not have
to be initialized. If we lift MEM_UNINIT, it then becomes: i) read into memory,
ii) memory must be initialized. This means that for bpf_*_check_mtu() we're
readding the issue we're trying to fix, that is, it would then be able to
write back into things like .rodata BPF maps. Follow-up work will rework the
MEM_UNINIT semantics such that the intent can be better expressed. For now
just clear the *mtu_len on error path which can be lifted later again.
Fixes: 8a67f2de9b ("bpf: expose bpf_strtol and bpf_strtoul to all program types")
Fixes: d7a4cb9b67 ("bpf: Introduce bpf_strtol and bpf_strtoul helpers")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/e5edd241-59e7-5e39-0ee5-a51e31b6840a@iogearbox.net
Link: https://lore.kernel.org/r/20240913191754.13290-5-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When checking malformed helper function signatures, also take other argument
types into account aside from just ARG_PTR_TO_UNINIT_MEM.
This concerns (formerly) ARG_PTR_TO_{INT,LONG} given uninitialized memory can
be passed there, too.
The func proto sanity check goes back to commit 435faee1aa ("bpf, verifier:
add ARG_PTR_TO_RAW_STACK type"), and its purpose was to detect wrong func protos
which had more than just one MEM_UNINIT-tagged type as arguments.
The reason more than one is currently not supported is as we mark stack slots with
STACK_MISC in check_helper_call() in case of raw mode based on meta.access_size to
allow uninitialized stack memory to be passed to helpers when they just write into
the buffer.
Probing for base type as well as MEM_UNINIT tagging ensures that other types do not
get missed (as it used to be the case for ARG_PTR_TO_{INT,LONG}).
Fixes: 57c3bb725a ("bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types")
Reported-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20240913191754.13290-4-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Lonial found an issue that despite user- and BPF-side frozen BPF map
(like in case of .rodata), it was still possible to write into it from
a BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT}
as arguments.
In check_func_arg() when the argument is as mentioned, the meta->raw_mode
is never set. Later, check_helper_mem_access(), under the case of
PTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the
subsequent call to check_map_access_type() and given the BPF map is
read-only it succeeds.
The helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT
when results are written into them as opposed to read out of them. The
latter indicates that it's okay to pass a pointer to uninitialized memory
as the memory is written to anyway.
However, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM
just with additional alignment requirement. So it is better to just get
rid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the
fixed size memory types. For this, add MEM_ALIGNED to additionally ensure
alignment given these helpers write directly into the args via *<ptr> = val.
The .arg*_size has been initialized reflecting the actual sizeof(*<ptr>).
MEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated
argument types, since in !MEM_FIXED_SIZE cases the verifier does not know
the buffer size a priori and therefore cannot blindly write *<ptr> = val.
Fixes: 57c3bb725a ("bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20240913191754.13290-3-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Both bpf_strtol() and bpf_strtoul() helpers passed a temporary "long long"
respectively "unsigned long long" to __bpf_strtoll() / __bpf_strtoull().
Later, the result was checked for truncation via _res != ({unsigned,} long)_res
as the destination buffer for the BPF helpers was of type {unsigned,} long
which is 32bit on 32bit architectures.
Given the latter was a bug in the helper signatures where the destination buffer
got adjusted to {s,u}64, the truncation check can now be removed.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240913191754.13290-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The bpf_strtol() and bpf_strtoul() helpers are currently broken on 32bit:
The argument type ARG_PTR_TO_LONG is BPF-side "long", not kernel-side "long"
and therefore always considered fixed 64bit no matter if 64 or 32bit underlying
architecture.
This contract breaks in case of the two mentioned helpers since their BPF_CALL
definition for the helpers was added with {unsigned,}long *res. Meaning, the
transition from BPF-side "long" (BPF program) to kernel-side "long" (BPF helper)
breaks here.
Both helpers call __bpf_strtoll() with "long long" correctly, but later assigning
the result into 32-bit "*(long *)" on 32bit architectures. From a BPF program
point of view, this means upper bits will be seen as uninitialised.
Therefore, fix both BPF_CALL signatures to {s,u}64 types to fix this situation.
Now, changing also uapi/bpf.h helper documentation which generates bpf_helper_defs.h
for BPF programs is tricky: Changing signatures there to __{s,u}64 would trigger
compiler warnings (incompatible pointer types passing 'long *' to parameter of type
'__s64 *' (aka 'long long *')) for existing BPF programs.
Leaving the signatures as-is would be fine as from BPF program point of view it is
still BPF-side "long" and thus equivalent to __{s,u}64 on 64 or 32bit underlying
architectures.
Note that bpf_strtol() and bpf_strtoul() are the only helpers with this issue.
Fixes: d7a4cb9b67 ("bpf: Introduce bpf_strtol and bpf_strtoul helpers")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/481fcec8-c12c-9abb-8ecb-76c71c009959@iogearbox.net
Link: https://lore.kernel.org/r/20240913191754.13290-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Zac Ecob reported a problem where a bpf program may cause kernel crash due
to the following error:
Oops: divide error: 0000 [#1] PREEMPT SMP KASAN PTI
The failure is due to the below signed divide:
LLONG_MIN/-1 where LLONG_MIN equals to -9,223,372,036,854,775,808.
LLONG_MIN/-1 is supposed to give a positive number 9,223,372,036,854,775,808,
but it is impossible since for 64-bit system, the maximum positive
number is 9,223,372,036,854,775,807. On x86_64, LLONG_MIN/-1 will
cause a kernel exception. On arm64, the result for LLONG_MIN/-1 is
LLONG_MIN.
Further investigation found all the following sdiv/smod cases may trigger
an exception when bpf program is running on x86_64 platform:
- LLONG_MIN/-1 for 64bit operation
- INT_MIN/-1 for 32bit operation
- LLONG_MIN%-1 for 64bit operation
- INT_MIN%-1 for 32bit operation
where -1 can be an immediate or in a register.
On arm64, there are no exceptions:
- LLONG_MIN/-1 = LLONG_MIN
- INT_MIN/-1 = INT_MIN
- LLONG_MIN%-1 = 0
- INT_MIN%-1 = 0
where -1 can be an immediate or in a register.
Insn patching is needed to handle the above cases and the patched codes
produced results aligned with above arm64 result. The below are pseudo
codes to handle sdiv/smod exceptions including both divisor -1 and divisor 0
and the divisor is stored in a register.
sdiv:
tmp = rX
tmp += 1 /* [-1, 0] -> [0, 1]
if tmp >(unsigned) 1 goto L2
if tmp == 0 goto L1
rY = 0
L1:
rY = -rY;
goto L3
L2:
rY /= rX
L3:
smod:
tmp = rX
tmp += 1 /* [-1, 0] -> [0, 1]
if tmp >(unsigned) 1 goto L1
if tmp == 1 (is64 ? goto L2 : goto L3)
rY = 0;
goto L2
L1:
rY %= rX
L2:
goto L4 // only when !is64
L3:
wY = wY // only when !is64
L4:
[1] https://lore.kernel.org/bpf/tPJLTEh7S_DxFEqAI2Ji5MBSoZVg7_G-Py2iaZpAaWtM961fFTWtsnlzwvTbzBzaUzwQAoNATXKUlt0LZOFgnDcIyKCswAnAGdUF3LBrhGQ=@protonmail.com/
Reported-by: Zac Ecob <zacecob@protonmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240913150326.1187788-1-yonghong.song@linux.dev
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 2024-09-11
We've added 12 non-merge commits during the last 16 day(s) which contain
a total of 20 files changed, 228 insertions(+), 30 deletions(-).
There's a minor merge conflict in drivers/net/netkit.c:
00d066a4d4 ("netdev_features: convert NETIF_F_LLTX to dev->lltx")
d966087948 ("netkit: Disable netpoll support")
The main changes are:
1) Enable bpf_dynptr_from_skb for tp_btf such that this can be used
to easily parse skbs in BPF programs attached to tracepoints,
from Philo Lu.
2) Add a cond_resched() point in BPF's sock_hash_free() as there have
been several syzbot soft lockup reports recently, from Eric Dumazet.
3) Fix xsk_buff_can_alloc() to account for queue_empty_descs which
got noticed when zero copy ice driver started to use it,
from Maciej Fijalkowski.
4) Move the xdp:xdp_cpumap_kthread tracepoint before cpumap pushes skbs
up via netif_receive_skb_list() to better measure latencies,
from Daniel Xu.
5) Follow-up to disable netpoll support from netkit, from Daniel Borkmann.
6) Improve xsk selftests to not assume a fixed MAX_SKB_FRAGS of 17 but
instead gather the actual value via /proc/sys/net/core/max_skb_frags,
also from Maciej Fijalkowski.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next:
sock_map: Add a cond_resched() in sock_hash_free()
selftests/bpf: Expand skb dynptr selftests for tp_btf
bpf: Allow bpf_dynptr_from_skb() for tp_btf
tcp: Use skb__nullable in trace_tcp_send_reset
selftests/bpf: Add test for __nullable suffix in tp_btf
bpf: Support __nullable argument suffix for tp_btf
bpf, cpumap: Move xdp:xdp_cpumap_kthread tracepoint before rcv
selftests/xsk: Read current MAX_SKB_FRAGS from sysctl knob
xsk: Bump xsk_queue::queue_empty_descs in xp_can_alloc()
tcp_bpf: Remove an unused parameter for bpf_tcp_ingress()
bpf, sockmap: Correct spelling skmsg.c
netkit: Disable netpoll support
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
====================
Link: https://patch.msgid.link/20240911211525.13834-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Keep file reference through the entire thing, don't bother with grabbing
struct path reference and while we are at it, don't confuse the hell out
of readers by random mix of path.dentry->d_sb and path.mnt->mnt_sb uses -
these two are equal, so just put one of those into a local variable and
use that.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Percpu map is often used, but the map value size limit often ignored,
like issue: https://github.com/iovisor/bcc/issues/2519. Actually,
percpu map value size is bound by PCPU_MIN_UNIT_SIZE, so we
can check the value size whether it exceeds PCPU_MIN_UNIT_SIZE first,
like percpu map of local_storage. Maybe the error message seems clearer
compared with "cannot allocate memory".
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Tao Chen <chen.dylane@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240910144111.1464912-2-chen.dylane@gmail.com
Add sleepable implementations of bpf_get_stack() and
bpf_get_task_stack() helpers and allow them to be used from sleepable
BPF program (e.g., sleepable uprobes).
Note, the stack trace IPs capturing itself is not sleepable (that would
need to be a separate project), only build ID fetching is sleepable and
thus more reliable, as it will wait for data to be paged in, if
necessary. For that we make use of sleepable build_id_parse()
implementation.
Now that build ID related internals in kernel/bpf/stackmap.c can be used
both in sleepable and non-sleepable contexts, we need to add additional
rcu_read_lock()/rcu_read_unlock() protection around fetching
perf_callchain_entry, but with the refactoring in previous commit it's
now pretty straightforward. We make sure to do rcu_read_unlock (in
sleepable mode only) right before stack_map_get_build_id_offset() call
which can sleep. By that time we don't have any more use of
perf_callchain_entry.
Note, bpf_get_task_stack() will fail for user mode if task != current.
And for kernel mode build ID are irrelevant. So in that sense adding
sleepable bpf_get_task_stack() implementation is a no-op. It feel right
to wire this up for symmetry and completeness, but I'm open to just
dropping it until we support `user && crosstask` condition.
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240829174232.3133883-10-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Change stack_map_get_build_id_offset() which is used to convert stack
trace IP addresses into build ID+offset pairs. Right now this function
accepts an array of u64s as an input, and uses array of
struct bpf_stack_build_id as an output.
This is problematic because u64 array is coming from
perf_callchain_entry, which is (non-sleepable) RCU protected, so once we
allows sleepable build ID fetching, this all breaks down.
But its actually pretty easy to make stack_map_get_build_id_offset()
works with array of struct bpf_stack_build_id as both input and output.
Which is what this patch is doing, eliminating the dependency on
perf_callchain_entry. We require caller to fill out
bpf_stack_build_id.ip fields (all other can be left uninitialized), and
update in place as we do build ID resolution.
We make sure to READ_ONCE() and cache locally current IP value as we
used it in a few places to find matching VMA and so on. Given this data
is directly accessible and modifiable by user's BPF code, we should make
sure to have a consistent view of it.
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240829174232.3133883-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Make it clear that build_id_parse() assumes that it can take no page
fault by renaming it and current few users to build_id_parse_nofault().
Also add build_id_parse() stub which for now falls back to non-sleepable
implementation, but will be changed in subsequent patches to take
advantage of sleepable context. PROCMAP_QUERY ioctl() on
/proc/<pid>/maps file is using build_id_parse() and will automatically
take advantage of more reliable sleepable context implementation.
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240829174232.3133883-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Pointers passed to tp_btf were trusted to be valid, but some tracepoints
do take NULL pointer as input, such as trace_tcp_send_reset(). Then the
invalid memory access cannot be detected by verifier.
This patch fix it by add a suffix "__nullable" to the unreliable
argument. The suffix is shown in btf, and PTR_MAYBE_NULL will be added
to nullable arguments. Then users must check the pointer before use it.
A problem here is that we use "btf_trace_##call" to search func_proto.
As it is a typedef, argument names as well as the suffix are not
recorded. To solve this, I use bpf_raw_event_map to find
"__bpf_trace##template" from "btf_trace_##call", and then we can see the
suffix.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240911033719.91468-2-lulie@linux.alibaba.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
cpumap takes RX processing out of softirq and onto a separate kthread.
Since the kthread needs to be scheduled in order to run (versus softirq
which does not), we can theoretically experience extra latency if the
system is under load and the scheduler is being unfair to us.
Moving the tracepoint to before passing the skb list up the stack allows
users to more accurately measure enqueue/dequeue latency introduced by
cpumap via xdp:xdp_cpumap_enqueue and xdp:xdp_cpumap_kthread tracepoints.
f9419f7bd7 ("bpf: cpumap add tracepoints") which added the tracepoints
states that the intent behind them was for general observability and for
a feedback loop to see if the queues are being overwhelmed. This change
does not mess with either of those use cases but rather adds a third
one.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://lore.kernel.org/bpf/47615d5b5e302e4bd30220473779e98b492d47cd.1725585718.git.dxu@dxuuu.xyz
When "arg#%d expected pointer to ctx, but got %s" error is printed, both
template parts actually point to the type of the argument, therefore, it
will also say "but got PTR", regardless of what was the actual register
type.
Fix the message to print the register type in the second part of the
template, change the existing test to adapt to the new format, and add a
new test to test the case when arg is a pointer to context, but reg is a
scalar.
Fixes: 00b85860fe ("bpf: Rewrite kfunc argument handling")
Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20240909133909.1315460-1-maxim@isovalent.com
Associate tracepoint and perf event program types with the kfunc tracing
hook. This allows calling kfuncs within these types of programs.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Link: https://lore.kernel.org/r/20240905223812.141857-2-inwardvessel@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This improves BTF data recorded about this function and makes
debugging/tracing better, because now command can be displayed as
symbolic name, instead of obscure number.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240905210520.2252984-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
