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author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-05-07 15:03:46 +0300 |
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committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-05-18 16:53:52 +0300 |
commit | e73aaae2fa9024832e1f42e30c787c7baf61d014 (patch) | |
tree | 151a956250ad489a31c98047f24ea82fa157a1a8 /drivers/char/random.c | |
parent | 791332b3cbb080510954a4c152ce02af8832eac9 (diff) | |
download | linux-e73aaae2fa9024832e1f42e30c787c7baf61d014.tar.xz |
siphash: use one source of truth for siphash permutations
The SipHash family of permutations is currently used in three places:
- siphash.c itself, used in the ordinary way it was intended.
- random32.c, in a construction from an anonymous contributor.
- random.c, as part of its fast_mix function.
Each one of these places reinvents the wheel with the same C code, same
rotation constants, and same symmetry-breaking constants.
This commit tidies things up a bit by placing macros for the
permutations and constants into siphash.h, where each of the three .c
users can access them. It also leaves a note dissuading more users of
them from emerging.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Diffstat (limited to 'drivers/char/random.c')
-rw-r--r-- | drivers/char/random.c | 30 |
1 files changed, 7 insertions, 23 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 8be3efd65ef2..c1763bcbcaed 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -52,6 +52,7 @@ #include <linux/uuid.h> #include <linux/uaccess.h> #include <linux/suspend.h> +#include <linux/siphash.h> #include <crypto/chacha.h> #include <crypto/blake2s.h> #include <asm/processor.h> @@ -1086,12 +1087,11 @@ struct fast_pool { static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = { #ifdef CONFIG_64BIT - /* SipHash constants */ - .pool = { 0x736f6d6570736575UL, 0x646f72616e646f6dUL, - 0x6c7967656e657261UL, 0x7465646279746573UL } +#define FASTMIX_PERM SIPHASH_PERMUTATION + .pool = { SIPHASH_CONST_0, SIPHASH_CONST_1, SIPHASH_CONST_2, SIPHASH_CONST_3 } #else - /* HalfSipHash constants */ - .pool = { 0, 0, 0x6c796765U, 0x74656462U } +#define FASTMIX_PERM HSIPHASH_PERMUTATION + .pool = { HSIPHASH_CONST_0, HSIPHASH_CONST_1, HSIPHASH_CONST_2, HSIPHASH_CONST_3 } #endif }; @@ -1103,27 +1103,11 @@ static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = { */ static void fast_mix(unsigned long s[4], unsigned long v1, unsigned long v2) { -#ifdef CONFIG_64BIT -#define PERM() do { \ - s[0] += s[1]; s[1] = rol64(s[1], 13); s[1] ^= s[0]; s[0] = rol64(s[0], 32); \ - s[2] += s[3]; s[3] = rol64(s[3], 16); s[3] ^= s[2]; \ - s[0] += s[3]; s[3] = rol64(s[3], 21); s[3] ^= s[0]; \ - s[2] += s[1]; s[1] = rol64(s[1], 17); s[1] ^= s[2]; s[2] = rol64(s[2], 32); \ -} while (0) -#else -#define PERM() do { \ - s[0] += s[1]; s[1] = rol32(s[1], 5); s[1] ^= s[0]; s[0] = rol32(s[0], 16); \ - s[2] += s[3]; s[3] = rol32(s[3], 8); s[3] ^= s[2]; \ - s[0] += s[3]; s[3] = rol32(s[3], 7); s[3] ^= s[0]; \ - s[2] += s[1]; s[1] = rol32(s[1], 13); s[1] ^= s[2]; s[2] = rol32(s[2], 16); \ -} while (0) -#endif - s[3] ^= v1; - PERM(); + FASTMIX_PERM(s[0], s[1], s[2], s[3]); s[0] ^= v1; s[3] ^= v2; - PERM(); + FASTMIX_PERM(s[0], s[1], s[2], s[3]); s[0] ^= v2; } |