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| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-10-23 22:06:00 +0200 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-11-18 02:18:10 +0100 |
| commit | b3883a9a1f09e7b41f4dcb1bbd7262216a62d253 (patch) | |
| tree | a3fc9ed3fee27e63a7b93252484e87e7de7cc1bc /include/linux/stackprotector.h | |
| parent | e8a533cbeb79809206f8724e89961e0079508c3c (diff) | |
| download | linux-b3883a9a1f09e7b41f4dcb1bbd7262216a62d253.tar.bz2 | |
stackprotector: move get_random_canary() into stackprotector.h
This has nothing to do with random.c and everything to do with stack
protectors. Yes, it uses randomness. But many things use randomness.
random.h and random.c are concerned with the generation of randomness,
not with each and every use. So move this function into the more
specific stackprotector.h file where it belongs.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Diffstat (limited to 'include/linux/stackprotector.h')
| -rw-r--r-- | include/linux/stackprotector.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/stackprotector.h b/include/linux/stackprotector.h index 4c678c4fec58..9c88707d9a0f 100644 --- a/include/linux/stackprotector.h +++ b/include/linux/stackprotector.h @@ -6,6 +6,25 @@ #include <linux/sched.h> #include <linux/random.h> +/* + * On 64-bit architectures, protect against non-terminated C string overflows + * by zeroing out the first byte of the canary; this leaves 56 bits of entropy. + */ +#ifdef CONFIG_64BIT +# ifdef __LITTLE_ENDIAN +# define CANARY_MASK 0xffffffffffffff00UL +# else /* big endian, 64 bits: */ +# define CANARY_MASK 0x00ffffffffffffffUL +# endif +#else /* 32 bits: */ +# define CANARY_MASK 0xffffffffUL +#endif + +static inline unsigned long get_random_canary(void) +{ + return get_random_long() & CANARY_MASK; +} + #if defined(CONFIG_STACKPROTECTOR) || defined(CONFIG_ARM64_PTR_AUTH) # include <asm/stackprotector.h> #else |