diff options
| -rw-r--r-- | include/linux/random.h | 2 | ||||
| -rw-r--r-- | lib/random32.c | 49 |
2 files changed, 51 insertions, 0 deletions
diff --git a/include/linux/random.h b/include/linux/random.h index db6debc6649e..d9846088c2c5 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -26,6 +26,7 @@ unsigned int get_random_int(void); unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len); u32 prandom_u32(void); +void prandom_bytes(void *buf, int nbytes); void prandom_seed(u32 seed); /* @@ -36,6 +37,7 @@ void prandom_seed(u32 seed); #define srandom32(seed) prandom_seed(seed) u32 prandom_u32_state(struct rnd_state *); +void prandom_bytes_state(struct rnd_state *state, void *buf, int nbytes); /* * Handle minimum values for seeds diff --git a/lib/random32.c b/lib/random32.c index d1830fade915..52280d5526be 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -77,6 +77,55 @@ u32 prandom_u32(void) } EXPORT_SYMBOL(prandom_u32); +/* + * prandom_bytes_state - get the requested number of pseudo-random bytes + * + * @state: pointer to state structure holding seeded state. + * @buf: where to copy the pseudo-random bytes to + * @bytes: the requested number of bytes + * + * This is used for pseudo-randomness with no outside seeding. + * For more random results, use prandom_bytes(). + */ +void prandom_bytes_state(struct rnd_state *state, void *buf, int bytes) +{ + unsigned char *p = buf; + int i; + + for (i = 0; i < round_down(bytes, sizeof(u32)); i += sizeof(u32)) { + u32 random = prandom_u32_state(state); + int j; + + for (j = 0; j < sizeof(u32); j++) { + p[i + j] = random; + random >>= BITS_PER_BYTE; + } + } + if (i < bytes) { + u32 random = prandom_u32_state(state); + + for (; i < bytes; i++) { + p[i] = random; + random >>= BITS_PER_BYTE; + } + } +} +EXPORT_SYMBOL(prandom_bytes_state); + +/** + * prandom_bytes - get the requested number of pseudo-random bytes + * @buf: where to copy the pseudo-random bytes to + * @bytes: the requested number of bytes + */ +void prandom_bytes(void *buf, int bytes) +{ + struct rnd_state *state = &get_cpu_var(net_rand_state); + + prandom_bytes_state(state, buf, bytes); + put_cpu_var(state); +} +EXPORT_SYMBOL(prandom_bytes); + /** * prandom_seed - add entropy to pseudo random number generator * @seed: seed value |