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kasan: support kasan.stacktrace for SW_TAGS

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Add support for the kasan.stacktrace command-line argument for Software
Tag-Based KASAN.

The following patch adds a command-line argument for selecting the stack
ring size, and, as the stack ring is supported by both the Software and
the Hardware Tag-Based KASAN modes, it is natural that both of them have
support for kasan.stacktrace too.

Link: https://lkml.kernel.org/r/3b43059103faa7f8796017847b7d674b658f11b5.1662411799.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2022-09-05 23:05:46 +02:00 committed by Andrew Morton
parent 7bc0584e5d
commit 7ebfce3312
5 changed files with 81 additions and 57 deletions
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15
Documentation/dev-tools/kasan.rst
View File

@ -111,9 +111,15 @@ parameter can be used to control panic and reporting behaviour:
report or also panic the kernel (default: ``report``). The panic happens even
if ``kasan_multi_shot`` is enabled.
Hardware Tag-Based KASAN mode (see the section about various modes below) is
intended for use in production as a security mitigation. Therefore, it supports
additional boot parameters that allow disabling KASAN or controlling features:
Software and Hardware Tag-Based KASAN modes (see the section about various
modes below) support disabling stack trace collection:
- ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack
traces collection (default: ``on``).
Hardware Tag-Based KASAN mode is intended for use in production as a security
mitigation. Therefore, it supports additional boot parameters that allow
disabling KASAN altogether or controlling its features:
- ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``).
@ -132,9 +138,6 @@ additional boot parameters that allow disabling KASAN or controlling features:
- ``kasan.vmalloc=off`` or ``=on`` disables or enables tagging of vmalloc
allocations (default: ``on``).
- ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack
traces collection (default: ``on``).
Error reports
~~~~~~~~~~~~~

39
mm/kasan/hw_tags.c
View File

@ -38,16 +38,9 @@ enum kasan_arg_vmalloc {
KASAN_ARG_VMALLOC_ON,
};
enum kasan_arg_stacktrace {
KASAN_ARG_STACKTRACE_DEFAULT,
KASAN_ARG_STACKTRACE_OFF,
KASAN_ARG_STACKTRACE_ON,
};
static enum kasan_arg kasan_arg __ro_after_init;
static enum kasan_arg_mode kasan_arg_mode __ro_after_init;
static enum kasan_arg_vmalloc kasan_arg_vmalloc __initdata;
static enum kasan_arg_stacktrace kasan_arg_stacktrace __initdata;
/*
* Whether KASAN is enabled at all.
@ -66,9 +59,6 @@ EXPORT_SYMBOL_GPL(kasan_mode);
/* Whether to enable vmalloc tagging. */
DEFINE_STATIC_KEY_TRUE(kasan_flag_vmalloc);
/* Whether to collect alloc/free stack traces. */
DEFINE_STATIC_KEY_TRUE(kasan_flag_stacktrace);
/* kasan=off/on */
static int __init early_kasan_flag(char *arg)
{
@ -122,23 +112,6 @@ static int __init early_kasan_flag_vmalloc(char *arg)
}
early_param("kasan.vmalloc", early_kasan_flag_vmalloc);
/* kasan.stacktrace=off/on */
static int __init early_kasan_flag_stacktrace(char *arg)
{
if (!arg)
return -EINVAL;
if (!strcmp(arg, "off"))
kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_OFF;
else if (!strcmp(arg, "on"))
kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_ON;
else
return -EINVAL;
return 0;
}
early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
static inline const char *kasan_mode_info(void)
{
if (kasan_mode == KASAN_MODE_ASYNC)
@ -213,17 +186,7 @@ void __init kasan_init_hw_tags(void)
break;
}
switch (kasan_arg_stacktrace) {
case KASAN_ARG_STACKTRACE_DEFAULT:
/* Default is specified by kasan_flag_stacktrace definition. */
break;
case KASAN_ARG_STACKTRACE_OFF:
static_branch_disable(&kasan_flag_stacktrace);
break;
case KASAN_ARG_STACKTRACE_ON:
static_branch_enable(&kasan_flag_stacktrace);
break;
}
kasan_init_tags();
/* KASAN is now initialized, enable it. */
static_branch_enable(&kasan_flag_enabled);

36
mm/kasan/kasan.h
View File

@ -8,13 +8,31 @@
#include <linux/kfence.h>
#include <linux/stackdepot.h>
#ifdef CONFIG_KASAN_HW_TAGS
#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
#include <linux/static_key.h>
DECLARE_STATIC_KEY_TRUE(kasan_flag_stacktrace);
static inline bool kasan_stack_collection_enabled(void)
{
return static_branch_unlikely(&kasan_flag_stacktrace);
}
#else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
static inline bool kasan_stack_collection_enabled(void)
{
return true;
}
#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
#ifdef CONFIG_KASAN_HW_TAGS
#include "../slab.h"
DECLARE_STATIC_KEY_TRUE(kasan_flag_vmalloc);
DECLARE_STATIC_KEY_TRUE(kasan_flag_stacktrace);
enum kasan_mode {
KASAN_MODE_SYNC,
@ -29,11 +47,6 @@ static inline bool kasan_vmalloc_enabled(void)
return static_branch_likely(&kasan_flag_vmalloc);
}
static inline bool kasan_stack_collection_enabled(void)
{
return static_branch_unlikely(&kasan_flag_stacktrace);
}
static inline bool kasan_async_fault_possible(void)
{
return kasan_mode == KASAN_MODE_ASYNC || kasan_mode == KASAN_MODE_ASYMM;
@ -46,11 +59,6 @@ static inline bool kasan_sync_fault_possible(void)
#else /* CONFIG_KASAN_HW_TAGS */
static inline bool kasan_stack_collection_enabled(void)
{
return true;
}
static inline bool kasan_async_fault_possible(void)
{
return false;
@ -410,6 +418,10 @@ static inline void kasan_enable_tagging(void) { }
#endif /* CONFIG_KASAN_HW_TAGS */
#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
void __init kasan_init_tags(void);
#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
#if defined(CONFIG_KASAN_HW_TAGS) && IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
void kasan_force_async_fault(void);

5
mm/kasan/sw_tags.c
View File

@ -42,7 +42,10 @@ void __init kasan_init_sw_tags(void)
for_each_possible_cpu(cpu)
per_cpu(prng_state, cpu) = (u32)get_cycles();
pr_info("KernelAddressSanitizer initialized (sw-tags)\n");
kasan_init_tags();
pr_info("KernelAddressSanitizer initialized (sw-tags, stacktrace=%s)\n",
kasan_stack_collection_enabled() ? "on" : "off");
}
/*

43
mm/kasan/tags.c
View File

@ -19,6 +19,17 @@
#include "kasan.h"
#include "../slab.h"
enum kasan_arg_stacktrace {
KASAN_ARG_STACKTRACE_DEFAULT,
KASAN_ARG_STACKTRACE_OFF,
KASAN_ARG_STACKTRACE_ON,
};
static enum kasan_arg_stacktrace kasan_arg_stacktrace __initdata;
/* Whether to collect alloc/free stack traces. */
DEFINE_STATIC_KEY_TRUE(kasan_flag_stacktrace);
/* Non-zero, as initial pointer values are 0. */
#define STACK_RING_BUSY_PTR ((void *)1)
@ -26,6 +37,38 @@ struct kasan_stack_ring stack_ring = {
.lock = __RW_LOCK_UNLOCKED(stack_ring.lock)
};
/* kasan.stacktrace=off/on */
static int __init early_kasan_flag_stacktrace(char *arg)
{
if (!arg)
return -EINVAL;
if (!strcmp(arg, "off"))
kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_OFF;
else if (!strcmp(arg, "on"))
kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_ON;
else
return -EINVAL;
return 0;
}
early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
void __init kasan_init_tags(void)
{
switch (kasan_arg_stacktrace) {
case KASAN_ARG_STACKTRACE_DEFAULT:
/* Default is specified by kasan_flag_stacktrace definition. */
break;
case KASAN_ARG_STACKTRACE_OFF:
static_branch_disable(&kasan_flag_stacktrace);
break;
case KASAN_ARG_STACKTRACE_ON:
static_branch_enable(&kasan_flag_stacktrace);
break;
}
}
static void save_stack_info(struct kmem_cache *cache, void *object,
gfp_t gfp_flags, bool is_free)
{