diff options
Diffstat (limited to 'include/linux/prandom.h')
| -rw-r--r-- | include/linux/prandom.h | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/include/linux/prandom.h b/include/linux/prandom.h index aa16e6468f91..709e8e69fb39 100644 --- a/include/linux/prandom.h +++ b/include/linux/prandom.h @@ -10,18 +10,41 @@ #include <linux/types.h> #include <linux/percpu.h> +#include <linux/siphash.h> u32 prandom_u32(void); void prandom_bytes(void *buf, size_t nbytes); void prandom_seed(u32 seed); void prandom_reseed_late(void); +#if BITS_PER_LONG == 64 +/* + * The core SipHash round function. Each line can be executed in + * parallel given enough CPU resources. + */ +#define PRND_SIPROUND(v0, v1, v2, v3) SIPHASH_PERMUTATION(v0, v1, v2, v3) + +#define PRND_K0 (SIPHASH_CONST_0 ^ SIPHASH_CONST_2) +#define PRND_K1 (SIPHASH_CONST_1 ^ SIPHASH_CONST_3) + +#elif BITS_PER_LONG == 32 +/* + * On 32-bit machines, we use HSipHash, a reduced-width version of SipHash. + * This is weaker, but 32-bit machines are not used for high-traffic + * applications, so there is less output for an attacker to analyze. + */ +#define PRND_SIPROUND(v0, v1, v2, v3) HSIPHASH_PERMUTATION(v0, v1, v2, v3) +#define PRND_K0 (HSIPHASH_CONST_0 ^ HSIPHASH_CONST_2) +#define PRND_K1 (HSIPHASH_CONST_1 ^ HSIPHASH_CONST_3) + +#else +#error Unsupported BITS_PER_LONG +#endif + struct rnd_state { __u32 s1, s2, s3, s4; }; -DECLARE_PER_CPU(struct rnd_state, net_rand_state); - u32 prandom_u32_state(struct rnd_state *state); void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); @@ -61,7 +84,7 @@ static inline u32 __seed(u32 x, u32 m) */ static inline void prandom_seed_state(struct rnd_state *state, u64 seed) { - u32 i = (seed >> 32) ^ (seed << 10) ^ seed; + u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL; state->s1 = __seed(i, 2U); state->s2 = __seed(i, 8U); |