leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

kasan: allow architectures to provide an outline readiness check

Browse Source 
Allow architectures to define a kasan_arch_is_ready() hook that bails out
of any function that's about to touch the shadow unless the arch says that
it is ready for the memory to be accessed.  This is fairly uninvasive and
should have a negligible performance penalty.

This will only work in outline mode, so an arch must specify
ARCH_DISABLE_KASAN_INLINE if it requires this.

Link: https://lkml.kernel.org/r/20210624034050.511391-3-dja@axtens.net
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Marco Elver <elver@google.com>
Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Daniel Axtens 2021-06-28 19:40:42 -07:00 committed by Linus Torvalds
parent 158f25522c
commit af3751f3c2
4 changed files with 18 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
mm/kasan/common.c
View File

@ -331,6 +331,9 @@ static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
u8 tag;
void *tagged_object;
if (!kasan_arch_is_ready())
return false;
tag = get_tag(object);
tagged_object = object;
object = kasan_reset_tag(object);

3
mm/kasan/generic.c
View File

@ -163,6 +163,9 @@ static __always_inline bool check_region_inline(unsigned long addr,
size_t size, bool write,
unsigned long ret_ip)
{
if (!kasan_arch_is_ready())
return true;
if (unlikely(size == 0))
return true;

6
mm/kasan/kasan.h
View File

@ -449,6 +449,12 @@ static inline void kasan_poison_last_granule(const void *address, size_t size) {
#endif /* CONFIG_KASAN_GENERIC */
#ifndef kasan_arch_is_ready
static inline bool kasan_arch_is_ready(void) { return true; }
#elif !defined(CONFIG_KASAN_GENERIC) || !defined(CONFIG_KASAN_OUTLINE)
#error kasan_arch_is_ready only works in KASAN generic outline mode!
#endif
/*
* Exported functions for interfaces called from assembly or from generated
* code. Declarations here to avoid warning about missing declarations.

6
mm/kasan/shadow.c
View File

@ -73,6 +73,9 @@ void kasan_poison(const void *addr, size_t size, u8 value, bool init)
{
void *shadow_start, *shadow_end;
if (!kasan_arch_is_ready())
return;
/*
* Perform shadow offset calculation based on untagged address, as
* some of the callers (e.g. kasan_poison_object_data) pass tagged
@ -99,6 +102,9 @@ EXPORT_SYMBOL(kasan_poison);
#ifdef CONFIG_KASAN_GENERIC
void kasan_poison_last_granule(const void *addr, size_t size)
{
if (!kasan_arch_is_ready())
return;
if (size & KASAN_GRANULE_MASK) {
u8 *shadow = (u8 *)kasan_mem_to_shadow(addr + size);
*shadow = size & KASAN_GRANULE_MASK;