Commit 3c9e3aa1 authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Linus Torvalds
Browse files

kasan: add tag related helper functions 

This commit adds a few helper functions, that are meant to be used to work
with tags embedded in the top byte of kernel pointers: to set, to get or
to reset the top byte.

Link: http://lkml.kernel.org/r/f6c6437bb8e143bc44f42c3c259c62e734be7935.1544099024.git.andreyknvl@google.com


Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9c23f847

arch/arm64/include/asm/kasan.h

+6 −2
Original line number Diff line number Diff line
@@ -4,12 +4,16 @@ 


#ifndef __ASSEMBLY__



#ifdef CONFIG_KASAN



#include <linux/linkage.h>

#include <asm/memory.h>

#include <asm/pgtable-types.h>



#define arch_kasan_set_tag(addr, tag)	__tag_set(addr, tag)

#define arch_kasan_reset_tag(addr)	__tag_reset(addr)

#define arch_kasan_get_tag(addr)	__tag_get(addr)



#ifdef CONFIG_KASAN



/*

 * KASAN_SHADOW_START: beginning of the kernel virtual addresses.

 * KASAN_SHADOW_END: KASAN_SHADOW_START + 1/N of kernel virtual addresses,

arch/arm64/include/asm/memory.h

+12 −0
Original line number Diff line number Diff line
@@ -226,6 +226,18 @@ extern u64 vabits_user; 
#define untagged_addr(addr)	\

	((__typeof__(addr))sign_extend64((u64)(addr), 55))



#ifdef CONFIG_KASAN_SW_TAGS

#define __tag_shifted(tag)	((u64)(tag) << 56)

#define __tag_set(addr, tag)	(__typeof__(addr))( \

		((u64)(addr) & ~__tag_shifted(0xff)) | __tag_shifted(tag))

#define __tag_reset(addr)	untagged_addr(addr)

#define __tag_get(addr)		(__u8)((u64)(addr) >> 56)

#else

#define __tag_set(addr, tag)	(addr)

#define __tag_reset(addr)	(addr)

#define __tag_get(addr)		0

#endif



/*

 * Physical vs virtual RAM address space conversion.  These are

 * private definitions which should NOT be used outside memory.h

arch/arm64/mm/kasan_init.c

+2 −0
Original line number Diff line number Diff line
@@ -252,6 +252,8 @@ void __init kasan_init(void) 
	memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);

	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));



	kasan_init_tags();



	/* At this point kasan is fully initialized. Enable error messages */

	init_task.kasan_depth = 0;

	pr_info("KernelAddressSanitizer initialized\n");

include/linux/kasan.h

+13 −0
Original line number Diff line number Diff line
@@ -169,6 +169,19 @@ static inline void kasan_cache_shutdown(struct kmem_cache *cache) {} 


#define KASAN_SHADOW_INIT 0xFF



void kasan_init_tags(void);



void *kasan_reset_tag(const void *addr);



#else /* CONFIG_KASAN_SW_TAGS */



static inline void kasan_init_tags(void) { }



static inline void *kasan_reset_tag(const void *addr)

{

	return (void *)addr;

}



#endif /* CONFIG_KASAN_SW_TAGS */



#endif /* LINUX_KASAN_H */

mm/kasan/kasan.h

+31 −0
Original line number Diff line number Diff line
@@ -8,6 +8,10 @@ 
#define KASAN_SHADOW_SCALE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT)

#define KASAN_SHADOW_MASK       (KASAN_SHADOW_SCALE_SIZE - 1)



#define KASAN_TAG_KERNEL	0xFF /* native kernel pointers tag */

#define KASAN_TAG_INVALID	0xFE /* inaccessible memory tag */

#define KASAN_TAG_MAX		0xFD /* maximum value for random tags */



#define KASAN_FREE_PAGE         0xFF  /* page was freed */

#define KASAN_PAGE_REDZONE      0xFE  /* redzone for kmalloc_large allocations */

#define KASAN_KMALLOC_REDZONE   0xFC  /* redzone inside slub object */
@@ -126,6 +130,33 @@ static inline void quarantine_reduce(void) { } 
static inline void quarantine_remove_cache(struct kmem_cache *cache) { }

#endif



#ifdef CONFIG_KASAN_SW_TAGS



u8 random_tag(void);



#else



static inline u8 random_tag(void)

{

	return 0;

}



#endif



#ifndef arch_kasan_set_tag

#define arch_kasan_set_tag(addr, tag)	((void *)(addr))

#endif

#ifndef arch_kasan_reset_tag

#define arch_kasan_reset_tag(addr)	((void *)(addr))

#endif

#ifndef arch_kasan_get_tag

#define arch_kasan_get_tag(addr)	0

#endif



#define set_tag(addr, tag)	((void *)arch_kasan_set_tag((addr), (tag)))

#define reset_tag(addr)		((void *)arch_kasan_reset_tag(addr))

#define get_tag(addr)		arch_kasan_get_tag(addr)



/*

 * Exported functions for interfaces called from assembly or from generated

 * code. Declarations here to avoid warning about missing declarations.

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