diff options
Diffstat (limited to 'include/linux/prandom.h')
| -rw-r--r-- | include/linux/prandom.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/prandom.h b/include/linux/prandom.h index cc1e71334e53..bbf4b4ad61df 100644 --- a/include/linux/prandom.h +++ b/include/linux/prandom.h @@ -16,6 +16,12 @@ void prandom_bytes(void *buf, size_t nbytes); void prandom_seed(u32 seed); void prandom_reseed_late(void); +DECLARE_PER_CPU(unsigned long, net_rand_noise); + +#define PRANDOM_ADD_NOISE(a, b, c, d) \ + prandom_u32_add_noise((unsigned long)(a), (unsigned long)(b), \ + (unsigned long)(c), (unsigned long)(d)) + #if BITS_PER_LONG == 64 /* * The core SipHash round function. Each line can be executed in @@ -50,6 +56,18 @@ void prandom_reseed_late(void); #error Unsupported BITS_PER_LONG #endif +static inline void prandom_u32_add_noise(unsigned long a, unsigned long b, + unsigned long c, unsigned long d) +{ + /* + * This is not used cryptographically; it's just + * a convenient 4-word hash function. (3 xor, 2 add, 2 rol) + */ + a ^= raw_cpu_read(net_rand_noise); + PRND_SIPROUND(a, b, c, d); + raw_cpu_write(net_rand_noise, d); +} + struct rnd_state { __u32 s1, s2, s3, s4; }; @@ -99,6 +117,7 @@ static inline void prandom_seed_state(struct rnd_state *state, u64 seed) state->s2 = __seed(i, 8U); state->s3 = __seed(i, 16U); state->s4 = __seed(i, 128U); + PRANDOM_ADD_NOISE(state, i, 0, 0); } /* Pseudo random number generator from numerical recipes. */ |