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stackleak: Rename STACKLEAK to KSTACK_ERASE

Browse Source 
In preparation for adding Clang sanitizer coverage stack depth tracking
that can support stack depth callbacks:

- Add the new top-level CONFIG_KSTACK_ERASE option which will be
  implemented either with the stackleak GCC plugin, or with the Clang
  stack depth callback support.
- Rename CONFIG_GCC_PLUGIN_STACKLEAK as needed to CONFIG_KSTACK_ERASE,
  but keep it for anything specific to the GCC plugin itself.
- Rename all exposed "STACKLEAK" names and files to "KSTACK_ERASE" (named
  for what it does rather than what it protects against), but leave as
  many of the internals alone as possible to avoid even more churn.

While here, also split "prev_lowest_stack" into CONFIG_KSTACK_ERASE_METRICS,
since that's the only place it is referenced from.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
This commit is contained in:
Kees Cook 2025-07-17 16:25:06 -07:00
parent fc07839203
commit 57fbad15c2
37 changed files with 101 additions and 95 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/admin-guide/sysctl/kernel.rst
View File

@ -1465,7 +1465,7 @@ stack_erasing
=============
This parameter can be used to control kernel stack erasing at the end
of syscalls for kernels built with ``CONFIG_GCC_PLUGIN_STACKLEAK``.
of syscalls for kernels built with ``CONFIG_KSTACK_ERASE``.
That erasing reduces the information which kernel stack leak bugs
can reveal and blocks some uninitialized stack variable attacks.
@ -1473,7 +1473,7 @@ The tradeoff is the performance impact: on a single CPU system kernel
compilation sees a 1% slowdown, other systems and workloads may vary.
= ====================================================================
0 Kernel stack erasing is disabled, STACKLEAK_METRICS are not updated.
0 Kernel stack erasing is disabled, KSTACK_ERASE_METRICS are not updated.
1 Kernel stack erasing is enabled (default), it is performed before
returning to the userspace at the end of syscalls.
= ====================================================================

2
Documentation/arch/x86/x86_64/mm.rst
View File

@ -176,5 +176,5 @@ Be very careful vs. KASLR when changing anything here. The KASLR address
range must not overlap with anything except the KASAN shadow area, which is
correct as KASAN disables KASLR.
For both 4- and 5-level layouts, the STACKLEAK_POISON value in the last 2MB
For both 4- and 5-level layouts, the KSTACK_ERASE_POISON value in the last 2MB
hole: ffffffffffff4111

2
Documentation/security/self-protection.rst
View File

@ -303,7 +303,7 @@ Memory poisoning
When releasing memory, it is best to poison the contents, to avoid reuse
attacks that rely on the old contents of memory. E.g., clear stack on a
syscall return (``CONFIG_GCC_PLUGIN_STACKLEAK``), wipe heap memory on a
syscall return (``CONFIG_KSTACK_ERASE``), wipe heap memory on a
free. This frustrates many uninitialized variable attacks, stack content
exposures, heap content exposures, and use-after-free attacks.

2
Documentation/translations/zh_CN/security/self-protection.rst
View File

@ -259,7 +259,7 @@ KALLSYSM，则会直接打印原始地址。
--------
在释放内存时，最好对内存内容进行清除处理，以防止攻击者重用内存中以前
的内容。例如，在系统调用返回时清除堆栈（CONFIG_GCC_PLUGIN_STACKLEAK）,
的内容。例如，在系统调用返回时清除堆栈（CONFIG_KSTACK_ERASE）,
在释放堆内容是清除其内容。这有助于防止许多未初始化变量攻击、堆栈内容
泄露、堆内容泄露以及使用后释放攻击（user-after-free）。

4
MAINTAINERS
View File

@ -9992,8 +9992,6 @@ L: linux-hardening@vger.kernel.org
S: Maintained
T: git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/hardening
F: Documentation/kbuild/gcc-plugins.rst
F: include/linux/stackleak.h
F: kernel/stackleak.c
F: scripts/Makefile.gcc-plugins
F: scripts/gcc-plugins/
@ -13087,10 +13085,12 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/har
F: Documentation/ABI/testing/sysfs-kernel-oops_count
F: Documentation/ABI/testing/sysfs-kernel-warn_count
F: arch/*/configs/hardening.config
F: include/linux/kstack_erase.h
F: include/linux/overflow.h
F: include/linux/randomize_kstack.h
F: include/linux/ucopysize.h
F: kernel/configs/hardening.config
F: kernel/kstack_erase.c
F: lib/tests/randstruct_kunit.c
F: lib/tests/usercopy_kunit.c
F: mm/usercopy.c

4
arch/Kconfig
View File

@ -630,11 +630,11 @@ config SECCOMP_CACHE_DEBUG
If unsure, say N.
config HAVE_ARCH_STACKLEAK
config HAVE_ARCH_KSTACK_ERASE
bool
help
An architecture should select this if it has the code which
fills the used part of the kernel stack with the STACKLEAK_POISON
fills the used part of the kernel stack with the KSTACK_ERASE_POISON
value before returning from system calls.
config HAVE_STACKPROTECTOR

2
arch/arm/Kconfig
View File

@ -87,11 +87,11 @@ config ARM
select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
select HAVE_ARCH_KSTACK_ERASE
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_PFN_VALID
select HAVE_ARCH_SECCOMP
select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
select HAVE_ARCH_STACKLEAK
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE

2
arch/arm/boot/compressed/Makefile
View File

@ -9,7 +9,7 @@ OBJS =
HEAD = head.o
OBJS += misc.o decompress.o
CFLAGS_decompress.o += $(DISABLE_STACKLEAK_PLUGIN)
CFLAGS_decompress.o += $(DISABLE_KSTACK_ERASE)
ifeq ($(CONFIG_DEBUG_UNCOMPRESS),y)
OBJS += debug.o
AFLAGS_head.o += -DDEBUG

2
arch/arm/kernel/entry-common.S
View File

@ -119,7 +119,7 @@ no_work_pending:
ct_user_enter save = 0
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
#ifdef CONFIG_KSTACK_ERASE
bl stackleak_erase_on_task_stack
#endif
restore_user_regs fast = 0, offset = 0

2
arch/arm64/Kconfig
View File

@ -187,12 +187,12 @@ config ARM64
select HAVE_ARCH_KCSAN if EXPERT
select HAVE_ARCH_KFENCE
select HAVE_ARCH_KGDB
select HAVE_ARCH_KSTACK_ERASE
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_STACKLEAK
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE

2
arch/arm64/kernel/entry.S
View File

@ -614,7 +614,7 @@ SYM_CODE_END(ret_to_kernel)
SYM_CODE_START_LOCAL(ret_to_user)
ldr x19, [tsk, #TSK_TI_FLAGS] // re-check for single-step
enable_step_tsk x19, x2
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
#ifdef CONFIG_KSTACK_ERASE
bl stackleak_erase_on_task_stack
#endif
kernel_exit 0

2
arch/arm64/kernel/pi/Makefile
View File

@ -2,7 +2,7 @@
# Copyright 2022 Google LLC
KBUILD_CFLAGS := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) -fpie \
-Os -DDISABLE_BRANCH_PROFILING $(DISABLE_STACKLEAK_PLUGIN) \
-Os -DDISABLE_BRANCH_PROFILING $(DISABLE_KSTACK_ERASE) \
$(DISABLE_LATENT_ENTROPY_PLUGIN) \
$(call cc-option,-mbranch-protection=none) \
-I$(srctree)/scripts/dtc/libfdt -fno-stack-protector \

2
arch/arm64/kvm/hyp/nvhe/Makefile
View File

@ -12,7 +12,7 @@ asflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS
ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS -D__DISABLE_TRACE_MMIO__
ccflags-y += -fno-stack-protector \
-DDISABLE_BRANCH_PROFILING \
$(DISABLE_STACKLEAK_PLUGIN)
$(DISABLE_KSTACK_ERASE)
hostprogs := gen-hyprel
HOST_EXTRACFLAGS += -I$(objtree)/include

2
arch/loongarch/Kconfig
View File

@ -120,11 +120,11 @@ config LOONGARCH
select HAVE_ARCH_KASAN
select HAVE_ARCH_KFENCE
select HAVE_ARCH_KGDB if PERF_EVENTS
select HAVE_ARCH_KSTACK_ERASE
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
select HAVE_ARCH_SECCOMP
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_STACKLEAK
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
select HAVE_ARCH_USERFAULTFD_MINOR if USERFAULTFD

2
arch/riscv/Kconfig
View File

@ -135,13 +135,13 @@ config RISCV
select HAVE_ARCH_KASAN if MMU && 64BIT
select HAVE_ARCH_KASAN_VMALLOC if MMU && 64BIT
select HAVE_ARCH_KFENCE if MMU && 64BIT
select HAVE_ARCH_KSTACK_ERASE
select HAVE_ARCH_KGDB if !XIP_KERNEL
select HAVE_ARCH_KGDB_QXFER_PKT
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_STACKLEAK
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU

2
arch/riscv/kernel/entry.S
View File

@ -220,7 +220,7 @@ SYM_CODE_START_NOALIGN(ret_from_exception)
#endif
bnez s0, 1f
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
#ifdef CONFIG_KSTACK_ERASE
call stackleak_erase_on_task_stack
#endif

2
arch/riscv/kernel/pi/Makefile
View File

@ -2,7 +2,7 @@
# This file was copied from arm64/kernel/pi/Makefile.
KBUILD_CFLAGS := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) -fpie \
-Os -DDISABLE_BRANCH_PROFILING $(DISABLE_STACKLEAK_PLUGIN) \
-Os -DDISABLE_BRANCH_PROFILING $(DISABLE_KSTACK_ERASE) \
$(call cc-option,-mbranch-protection=none) \
-I$(srctree)/scripts/dtc/libfdt -fno-stack-protector \
-include $(srctree)/include/linux/hidden.h \

2
arch/riscv/purgatory/Makefile
View File

@ -53,7 +53,7 @@ targets += purgatory.ro purgatory.chk
PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
PURGATORY_CFLAGS := -mcmodel=medany -ffreestanding -fno-zero-initialized-in-bss
PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
PURGATORY_CFLAGS += $(DISABLE_KSTACK_ERASE) -DDISABLE_BRANCH_PROFILING
PURGATORY_CFLAGS += -fno-stack-protector -g0
# Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That

2
arch/s390/Kconfig
View File

@ -176,10 +176,10 @@ config S390
select HAVE_ARCH_KCSAN
select HAVE_ARCH_KMSAN
select HAVE_ARCH_KFENCE
select HAVE_ARCH_KSTACK_ERASE
select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_SOFT_DIRTY
select HAVE_ARCH_STACKLEAK
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
select HAVE_ARCH_VMAP_STACK

2
arch/s390/kernel/entry.S
View File

@ -124,7 +124,7 @@ _LPP_OFFSET = __LC_LPP
#endif
.macro STACKLEAK_ERASE
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
#ifdef CONFIG_KSTACK_ERASE
brasl %r14,stackleak_erase_on_task_stack
#endif
.endm

2
arch/x86/Kconfig
View File

@ -204,13 +204,13 @@ config X86
select HAVE_ARCH_KFENCE
select HAVE_ARCH_KMSAN if X86_64
select HAVE_ARCH_KGDB
select HAVE_ARCH_KSTACK_ERASE
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_STACKLEAK
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64

4
arch/x86/entry/calling.h
View File

@ -369,7 +369,7 @@ For 32-bit we have the following conventions - kernel is built with
.endm
.macro STACKLEAK_ERASE_NOCLOBBER
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
#ifdef CONFIG_KSTACK_ERASE
PUSH_AND_CLEAR_REGS
call stackleak_erase
POP_REGS
@ -388,7 +388,7 @@ For 32-bit we have the following conventions - kernel is built with
#endif /* !CONFIG_X86_64 */
.macro STACKLEAK_ERASE
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
#ifdef CONFIG_KSTACK_ERASE
call stackleak_erase
#endif
.endm

2
arch/x86/purgatory/Makefile
View File

@ -35,7 +35,7 @@ targets += purgatory.ro purgatory.chk
PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
PURGATORY_CFLAGS := -mcmodel=small -ffreestanding -fno-zero-initialized-in-bss -g0
PURGATORY_CFLAGS += -fpic -fvisibility=hidden
PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
PURGATORY_CFLAGS += $(DISABLE_KSTACK_ERASE) -DDISABLE_BRANCH_PROFILING
PURGATORY_CFLAGS += -fno-stack-protector
# Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That

8
drivers/firmware/efi/libstub/Makefile
View File

@ -22,16 +22,16 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -std=gnu11 \
# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
# disable the stackleak plugin
cflags-$(CONFIG_ARM64) += -fpie $(DISABLE_STACKLEAK_PLUGIN) \
cflags-$(CONFIG_ARM64) += -fpie $(DISABLE_KSTACK_ERASE) \
-fno-unwind-tables -fno-asynchronous-unwind-tables
cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
-DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
-DEFI_HAVE_STRCMP -fno-builtin -fpic \
$(call cc-option,-mno-single-pic-base) \
$(DISABLE_STACKLEAK_PLUGIN)
$(DISABLE_KSTACK_ERASE)
cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax \
$(DISABLE_STACKLEAK_PLUGIN)
cflags-$(CONFIG_LOONGARCH) += -fpie $(DISABLE_STACKLEAK_PLUGIN)
$(DISABLE_KSTACK_ERASE)
cflags-$(CONFIG_LOONGARCH) += -fpie $(DISABLE_KSTACK_ERASE)
cflags-$(CONFIG_EFI_PARAMS_FROM_FDT) += -I$(srctree)/scripts/dtc/libfdt

2
drivers/misc/lkdtm/Makefile
View File

@ -8,7 +8,7 @@ lkdtm-$(CONFIG_LKDTM) += perms.o
lkdtm-$(CONFIG_LKDTM) += refcount.o
lkdtm-$(CONFIG_LKDTM) += rodata_objcopy.o
lkdtm-$(CONFIG_LKDTM) += usercopy.o
lkdtm-$(CONFIG_LKDTM) += stackleak.o
lkdtm-$(CONFIG_LKDTM) += kstack_erase.o
lkdtm-$(CONFIG_LKDTM) += cfi.o
lkdtm-$(CONFIG_LKDTM) += fortify.o
lkdtm-$(CONFIG_PPC_64S_HASH_MMU) += powerpc.o

26
drivers/misc/lkdtm/stackleak.c → drivers/misc/lkdtm/kstack_erase.c
View File

@ -1,7 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
/*
* This code tests that the current task stack is properly erased (filled
* with STACKLEAK_POISON).
* with KSTACK_ERASE_POISON).
*
* Authors:
* Alexander Popov <alex.popov@linux.com>
@ -9,9 +9,9 @@
*/
#include "lkdtm.h"
#include <linux/stackleak.h>
#include <linux/kstack_erase.h>
#if defined(CONFIG_GCC_PLUGIN_STACKLEAK)
#if defined(CONFIG_KSTACK_ERASE)
/*
* Check that stackleak tracks the lowest stack pointer and erases the stack
* below this as expected.
@ -85,7 +85,7 @@ static void noinstr check_stackleak_irqoff(void)
while (poison_low > task_stack_low) {
poison_low -= sizeof(unsigned long);
if (*(unsigned long *)poison_low == STACKLEAK_POISON)
if (*(unsigned long *)poison_low == KSTACK_ERASE_POISON)
continue;
instrumentation_begin();
@ -96,7 +96,7 @@ static void noinstr check_stackleak_irqoff(void)
}
instrumentation_begin();
pr_info("stackleak stack usage:\n"
pr_info("kstack erase stack usage:\n"
" high offset: %lu bytes\n"
" current: %lu bytes\n"
" lowest: %lu bytes\n"
@ -121,7 +121,7 @@ static void noinstr check_stackleak_irqoff(void)
instrumentation_end();
}
static void lkdtm_STACKLEAK_ERASING(void)
static void lkdtm_KSTACK_ERASE(void)
{
unsigned long flags;
@ -129,19 +129,19 @@ static void lkdtm_STACKLEAK_ERASING(void)
check_stackleak_irqoff();
local_irq_restore(flags);
}
#else /* defined(CONFIG_GCC_PLUGIN_STACKLEAK) */
static void lkdtm_STACKLEAK_ERASING(void)
#else /* defined(CONFIG_KSTACK_ERASE) */
static void lkdtm_KSTACK_ERASE(void)
{
if (IS_ENABLED(CONFIG_HAVE_ARCH_STACKLEAK)) {
pr_err("XFAIL: stackleak is not enabled (CONFIG_GCC_PLUGIN_STACKLEAK=n)\n");
if (IS_ENABLED(CONFIG_HAVE_ARCH_KSTACK_ERASE)) {
pr_err("XFAIL: stackleak is not enabled (CONFIG_KSTACK_ERASE=n)\n");
} else {
pr_err("XFAIL: stackleak is not supported on this arch (HAVE_ARCH_STACKLEAK=n)\n");
pr_err("XFAIL: stackleak is not supported on this arch (HAVE_ARCH_KSTACK_ERASE=n)\n");
}
}
#endif /* defined(CONFIG_GCC_PLUGIN_STACKLEAK) */
#endif /* defined(CONFIG_KSTACK_ERASE) */
static struct crashtype crashtypes[] = {
CRASHTYPE(STACKLEAK_ERASING),
CRASHTYPE(KSTACK_ERASE),
};
struct crashtype_category stackleak_crashtypes = {

6
fs/proc/base.c
View File

@ -3291,7 +3291,7 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns,
}
#endif /* CONFIG_KSM */
#ifdef CONFIG_STACKLEAK_METRICS
#ifdef CONFIG_KSTACK_ERASE_METRICS
static int proc_stack_depth(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
@ -3304,7 +3304,7 @@ static int proc_stack_depth(struct seq_file *m, struct pid_namespace *ns,
prev_depth, depth);
return 0;
}
#endif /* CONFIG_STACKLEAK_METRICS */
#endif /* CONFIG_KSTACK_ERASE_METRICS */
/*
* Thread groups
@ -3411,7 +3411,7 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_LIVEPATCH
ONE("patch_state", S_IRUSR, proc_pid_patch_state),
#endif
#ifdef CONFIG_STACKLEAK_METRICS
#ifdef CONFIG_KSTACK_ERASE_METRICS
ONE("stack_depth", S_IRUGO, proc_stack_depth),
#endif
#ifdef CONFIG_PROC_PID_ARCH_STATUS

18
include/linux/stackleak.h → include/linux/kstack_erase.h
View File

@ -1,6 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_STACKLEAK_H
#define _LINUX_STACKLEAK_H
#ifndef _LINUX_KSTACK_ERASE_H
#define _LINUX_KSTACK_ERASE_H
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
@ -9,10 +9,10 @@
* Check that the poison value points to the unused hole in the
* virtual memory map for your platform.
*/
#define STACKLEAK_POISON -0xBEEF
#define STACKLEAK_SEARCH_DEPTH 128
#define KSTACK_ERASE_POISON -0xBEEF
#define KSTACK_ERASE_SEARCH_DEPTH 128
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
#ifdef CONFIG_KSTACK_ERASE
#include <asm/stacktrace.h>
#include <linux/linkage.h>
@ -50,7 +50,7 @@ stackleak_task_high_bound(const struct task_struct *tsk)
static __always_inline unsigned long
stackleak_find_top_of_poison(const unsigned long low, const unsigned long high)
{
const unsigned int depth = STACKLEAK_SEARCH_DEPTH / sizeof(unsigned long);
const unsigned int depth = KSTACK_ERASE_SEARCH_DEPTH / sizeof(unsigned long);
unsigned int poison_count = 0;
unsigned long poison_high = high;
unsigned long sp = high;
@ -58,7 +58,7 @@ stackleak_find_top_of_poison(const unsigned long low, const unsigned long high)
while (sp > low && poison_count < depth) {
sp -= sizeof(unsigned long);
if (*(unsigned long *)sp == STACKLEAK_POISON) {
if (*(unsigned long *)sp == KSTACK_ERASE_POISON) {
poison_count++;
} else {
poison_count = 0;
@ -72,7 +72,7 @@ stackleak_find_top_of_poison(const unsigned long low, const unsigned long high)
static inline void stackleak_task_init(struct task_struct *t)
{
t->lowest_stack = stackleak_task_low_bound(t);
# ifdef CONFIG_STACKLEAK_METRICS
# ifdef CONFIG_KSTACK_ERASE_METRICS
t->prev_lowest_stack = t->lowest_stack;
# endif
}
@ -82,7 +82,7 @@ asmlinkage void noinstr stackleak_erase_on_task_stack(void);
asmlinkage void noinstr stackleak_erase_off_task_stack(void);
void __no_caller_saved_registers noinstr stackleak_track_stack(void);
#else /* !CONFIG_GCC_PLUGIN_STACKLEAK */
#else /* !CONFIG_KSTACK_ERASE */
static inline void stackleak_task_init(struct task_struct *t) { }
#endif

4
include/linux/sched.h
View File

@ -1607,8 +1607,10 @@ struct task_struct {
/* Used by BPF for per-TASK xdp storage */
struct bpf_net_context *bpf_net_context;
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
#ifdef CONFIG_KSTACK_ERASE
unsigned long lowest_stack;
#endif
#ifdef CONFIG_KSTACK_ERASE_METRICS
unsigned long prev_lowest_stack;
#endif

10
kernel/Makefile
View File

@ -139,11 +139,11 @@ obj-$(CONFIG_WATCH_QUEUE) += watch_queue.o
obj-$(CONFIG_RESOURCE_KUNIT_TEST) += resource_kunit.o
obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o
CFLAGS_stackleak.o += $(DISABLE_STACKLEAK_PLUGIN)
obj-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak.o
KASAN_SANITIZE_stackleak.o := n
KCSAN_SANITIZE_stackleak.o := n
KCOV_INSTRUMENT_stackleak.o := n
CFLAGS_kstack_erase.o += $(DISABLE_KSTACK_ERASE)
obj-$(CONFIG_KSTACK_ERASE) += kstack_erase.o
KASAN_SANITIZE_kstack_erase.o := n
KCSAN_SANITIZE_kstack_erase.o := n
KCOV_INSTRUMENT_kstack_erase.o := n
obj-$(CONFIG_SCF_TORTURE_TEST) += scftorture.o

2
kernel/fork.c
View File

@ -93,7 +93,7 @@
#include <linux/kcov.h>
#include <linux/livepatch.h>
#include <linux/thread_info.h>
#include <linux/stackleak.h>
#include <linux/kstack_erase.h>
#include <linux/kasan.h>
#include <linux/scs.h>
#include <linux/io_uring.h>

18
kernel/stackleak.c → kernel/kstack_erase.c
View File

@ -6,14 +6,14 @@
*
* Author: Alexander Popov <alex.popov@linux.com>
*
* STACKLEAK reduces the information which kernel stack leak bugs can
* KSTACK_ERASE reduces the information which kernel stack leak bugs can
* reveal and blocks some uninitialized stack variable attacks.
*/
#include <linux/stackleak.h>
#include <linux/kstack_erase.h>
#include <linux/kprobes.h>
#ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
#ifdef CONFIG_KSTACK_ERASE_RUNTIME_DISABLE
#include <linux/jump_label.h>
#include <linux/string_choices.h>
#include <linux/sysctl.h>
@ -68,7 +68,7 @@ late_initcall(stackleak_sysctls_init);
#define skip_erasing() static_branch_unlikely(&stack_erasing_bypass)
#else
#define skip_erasing() false
#endif /* CONFIG_STACKLEAK_RUNTIME_DISABLE */
#endif /* CONFIG_KSTACK_ERASE_RUNTIME_DISABLE */
#ifndef __stackleak_poison
static __always_inline void __stackleak_poison(unsigned long erase_low,
@ -91,7 +91,7 @@ static __always_inline void __stackleak_erase(bool on_task_stack)
erase_low = stackleak_find_top_of_poison(task_stack_low,
current->lowest_stack);
#ifdef CONFIG_STACKLEAK_METRICS
#ifdef CONFIG_KSTACK_ERASE_METRICS
current->prev_lowest_stack = erase_low;
#endif
@ -113,7 +113,7 @@ static __always_inline void __stackleak_erase(bool on_task_stack)
else
erase_high = task_stack_high;
__stackleak_poison(erase_low, erase_high, STACKLEAK_POISON);
__stackleak_poison(erase_low, erase_high, KSTACK_ERASE_POISON);
/* Reset the 'lowest_stack' value for the next syscall */
current->lowest_stack = task_stack_high;
@ -161,11 +161,11 @@ void __used __no_caller_saved_registers noinstr stackleak_track_stack(void)
unsigned long sp = current_stack_pointer;
/*
* Having CONFIG_STACKLEAK_TRACK_MIN_SIZE larger than
* STACKLEAK_SEARCH_DEPTH makes the poison search in
* Having CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE larger than
* KSTACK_ERASE_SEARCH_DEPTH makes the poison search in
* stackleak_erase() unreliable. Let's prevent that.
*/
BUILD_BUG_ON(CONFIG_STACKLEAK_TRACK_MIN_SIZE > STACKLEAK_SEARCH_DEPTH);
BUILD_BUG_ON(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE > KSTACK_ERASE_SEARCH_DEPTH);
/* 'lowest_stack' should be aligned on the register width boundary */
sp = ALIGN(sp, sizeof(unsigned long));

2
lib/Makefile
View File

@ -337,7 +337,7 @@ obj-$(CONFIG_UBSAN) += ubsan.o
UBSAN_SANITIZE_ubsan.o := n
KASAN_SANITIZE_ubsan.o := n
KCSAN_SANITIZE_ubsan.o := n
CFLAGS_ubsan.o := -fno-stack-protector $(DISABLE_STACKLEAK_PLUGIN)
CFLAGS_ubsan.o := -fno-stack-protector $(DISABLE_KSTACK_ERASE)
obj-$(CONFIG_SBITMAP) += sbitmap.o

6
scripts/Makefile.gcc-plugins
View File

@ -12,15 +12,15 @@ gcc-plugin-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak_plugin.so
gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+= -DSTACKLEAK_PLUGIN
gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+= -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_STACKLEAK_TRACK_MIN_SIZE)
+= -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE)
gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+= -fplugin-arg-stackleak_plugin-arch=$(SRCARCH)
gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK_VERBOSE) \
+= -fplugin-arg-stackleak_plugin-verbose
ifdef CONFIG_GCC_PLUGIN_STACKLEAK
DISABLE_STACKLEAK_PLUGIN += -fplugin-arg-stackleak_plugin-disable
DISABLE_KSTACK_ERASE += -fplugin-arg-stackleak_plugin-disable
endif
export DISABLE_STACKLEAK_PLUGIN
export DISABLE_KSTACK_ERASE
# All the plugin CFLAGS are collected here in case a build target needs to
# filter them out of the KBUILD_CFLAGS.

36
security/Kconfig.hardening
View File

@ -82,10 +82,10 @@ choice
endchoice
config GCC_PLUGIN_STACKLEAK
config KSTACK_ERASE
bool "Poison kernel stack before returning from syscalls"
depends on HAVE_ARCH_KSTACK_ERASE
depends on GCC_PLUGINS
depends on HAVE_ARCH_STACKLEAK
help
This option makes the kernel erase the kernel stack before
returning from system calls. This has the effect of leaving
@ -103,6 +103,10 @@ config GCC_PLUGIN_STACKLEAK
are advised to test this feature on your expected workload before
deploying it.
config GCC_PLUGIN_STACKLEAK
def_bool KSTACK_ERASE
depends on GCC_PLUGINS
help
This plugin was ported from grsecurity/PaX. More information at:
* https://grsecurity.net/
* https://pax.grsecurity.net/
@ -117,37 +121,37 @@ config GCC_PLUGIN_STACKLEAK_VERBOSE
instrumented. This is useful for comparing coverage between
builds.
config STACKLEAK_TRACK_MIN_SIZE
int "Minimum stack frame size of functions tracked by STACKLEAK"
config KSTACK_ERASE_TRACK_MIN_SIZE
int "Minimum stack frame size of functions tracked by KSTACK_ERASE"
default 100
range 0 4096
depends on GCC_PLUGIN_STACKLEAK
depends on KSTACK_ERASE
help
The STACKLEAK gcc plugin instruments the kernel code for tracking
The KSTACK_ERASE option instruments the kernel code for tracking
the lowest border of the kernel stack (and for some other purposes).
It inserts the stackleak_track_stack() call for the functions with
a stack frame size greater than or equal to this parameter.
If unsure, leave the default value 100.
config STACKLEAK_METRICS
bool "Show STACKLEAK metrics in the /proc file system"
depends on GCC_PLUGIN_STACKLEAK
config KSTACK_ERASE_METRICS
bool "Show KSTACK_ERASE metrics in the /proc file system"
depends on KSTACK_ERASE
depends on PROC_FS
help
If this is set, STACKLEAK metrics for every task are available in
the /proc file system. In particular, /proc/<pid>/stack_depth
If this is set, KSTACK_ERASE metrics for every task are available
in the /proc file system. In particular, /proc/<pid>/stack_depth
shows the maximum kernel stack consumption for the current and
previous syscalls. Although this information is not precise, it
can be useful for estimating the STACKLEAK performance impact for
your workloads.
can be useful for estimating the KSTACK_ERASE performance impact
for your workloads.
config STACKLEAK_RUNTIME_DISABLE
config KSTACK_ERASE_RUNTIME_DISABLE
bool "Allow runtime disabling of kernel stack erasing"
depends on GCC_PLUGIN_STACKLEAK
depends on KSTACK_ERASE
help
This option provides 'stack_erasing' sysctl, which can be used in
runtime to control kernel stack erasing for kernels built with
CONFIG_GCC_PLUGIN_STACKLEAK.
CONFIG_KSTACK_ERASE.
config INIT_ON_ALLOC_DEFAULT_ON
bool "Enable heap memory zeroing on allocation by default"

2
tools/objtool/check.c
View File

@ -1192,7 +1192,7 @@ static const char *uaccess_safe_builtin[] = {
"__ubsan_handle_type_mismatch_v1",
"__ubsan_handle_shift_out_of_bounds",
"__ubsan_handle_load_invalid_value",
/* STACKLEAK */
/* KSTACK_ERASE */
"stackleak_track_stack",
/* TRACE_BRANCH_PROFILING */
"ftrace_likely_update",

2
tools/testing/selftests/lkdtm/config
View File

@ -2,7 +2,7 @@ CONFIG_LKDTM=y
CONFIG_DEBUG_LIST=y
CONFIG_SLAB_FREELIST_HARDENED=y
CONFIG_FORTIFY_SOURCE=y
CONFIG_GCC_PLUGIN_STACKLEAK=y
CONFIG_KSTACK_ERASE=y
CONFIG_HARDENED_USERCOPY=y
CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
CONFIG_INIT_ON_FREE_DEFAULT_ON=y