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authorJason A. Donenfeld <Jason@zx2c4.com>2022-05-07 14:03:46 +0200
committerJason A. Donenfeld <Jason@zx2c4.com>2022-05-18 15:53:52 +0200
commite73aaae2fa9024832e1f42e30c787c7baf61d014 (patch)
tree151a956250ad489a31c98047f24ea82fa157a1a8 /lib/siphash.c
parent791332b3cbb080510954a4c152ce02af8832eac9 (diff)
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 'lib/siphash.c')
-rw-r--r--lib/siphash.c32
1 files changed, 10 insertions, 22 deletions
diff --git a/lib/siphash.c b/lib/siphash.c
index 72b9068ab57b..71d315a6ad62 100644
--- a/lib/siphash.c
+++ b/lib/siphash.c
@@ -18,19 +18,13 @@
#include <asm/word-at-a-time.h>
#endif
-#define SIPROUND \
- do { \
- v0 += v1; v1 = rol64(v1, 13); v1 ^= v0; v0 = rol64(v0, 32); \
- v2 += v3; v3 = rol64(v3, 16); v3 ^= v2; \
- v0 += v3; v3 = rol64(v3, 21); v3 ^= v0; \
- v2 += v1; v1 = rol64(v1, 17); v1 ^= v2; v2 = rol64(v2, 32); \
- } while (0)
+#define SIPROUND SIPHASH_PERMUTATION(v0, v1, v2, v3)
#define PREAMBLE(len) \
- u64 v0 = 0x736f6d6570736575ULL; \
- u64 v1 = 0x646f72616e646f6dULL; \
- u64 v2 = 0x6c7967656e657261ULL; \
- u64 v3 = 0x7465646279746573ULL; \
+ u64 v0 = SIPHASH_CONST_0; \
+ u64 v1 = SIPHASH_CONST_1; \
+ u64 v2 = SIPHASH_CONST_2; \
+ u64 v3 = SIPHASH_CONST_3; \
u64 b = ((u64)(len)) << 56; \
v3 ^= key->key[1]; \
v2 ^= key->key[0]; \
@@ -389,19 +383,13 @@ u32 hsiphash_4u32(const u32 first, const u32 second, const u32 third,
}
EXPORT_SYMBOL(hsiphash_4u32);
#else
-#define HSIPROUND \
- do { \
- v0 += v1; v1 = rol32(v1, 5); v1 ^= v0; v0 = rol32(v0, 16); \
- v2 += v3; v3 = rol32(v3, 8); v3 ^= v2; \
- v0 += v3; v3 = rol32(v3, 7); v3 ^= v0; \
- v2 += v1; v1 = rol32(v1, 13); v1 ^= v2; v2 = rol32(v2, 16); \
- } while (0)
+#define HSIPROUND HSIPHASH_PERMUTATION(v0, v1, v2, v3)
#define HPREAMBLE(len) \
- u32 v0 = 0; \
- u32 v1 = 0; \
- u32 v2 = 0x6c796765U; \
- u32 v3 = 0x74656462U; \
+ u32 v0 = HSIPHASH_CONST_0; \
+ u32 v1 = HSIPHASH_CONST_1; \
+ u32 v2 = HSIPHASH_CONST_2; \
+ u32 v3 = HSIPHASH_CONST_3; \
u32 b = ((u32)(len)) << 24; \
v3 ^= key->key[1]; \
v2 ^= key->key[0]; \