Messages in this thread Patch in this message | | | From | Akinobu Mita <> | Subject | [PATCH 1/9] random32: introduce random32_get_bytes() and prandom32_get_bytes() | Date | Sun, 28 Oct 2012 16:18:58 +0900 |
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Add functions to get the requested number of pseudo-random bytes.
The difference from get_random_bytes() is that it uses pseudo-random numbers generated by random32. It is fast, suitable for generating random bytes for testing, and reproducible if prandom32 interface is used.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Artem Bityutskiy <dedekind1@gmail.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: linux-mtd@lists.infradead.org --- include/linux/random.h | 2 ++ lib/random32.c | 38 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+)
diff --git a/include/linux/random.h b/include/linux/random.h index 6330ed4..eedf429b 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -27,8 +27,10 @@ unsigned long randomize_range(unsigned long start, unsigned long end, unsigned l u32 random32(void); void srandom32(u32 seed); +void random32_get_bytes(void *buf, int nbytes); u32 prandom32(struct rnd_state *); +void prandom32_get_bytes(struct rnd_state *state, void *buf, int nbytes); /* * Handle minimum values for seeds diff --git a/lib/random32.c b/lib/random32.c index 938bde5..aee87dd 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -61,6 +61,44 @@ u32 prandom32(struct rnd_state *state) EXPORT_SYMBOL(prandom32); /** + * prandom32_get_bytes - 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 random32_get_bytes(). + */ +void prandom32_get_bytes(struct rnd_state *state, void *buf, int bytes) +{ + unsigned char *p = buf; + + for (; bytes > 0 && ((unsigned long)p) % sizeof(u32); bytes--, p++) + *p = prandom32(state); + + for (; bytes > sizeof(u32) - 1; bytes -= sizeof(u32), p += sizeof(u32)) + *(u32 *)p = prandom32(state); + + for (; bytes > 0; bytes--, p++) + *p = prandom32(state); +} +EXPORT_SYMBOL(prandom32_get_bytes); + +/** + * random32_get_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 random32_get_bytes(void *buf, int bytes) +{ + struct rnd_state *state = &get_cpu_var(net_rand_state); + + prandom32_get_bytes(state, buf, bytes); + put_cpu_var(state); +} +EXPORT_SYMBOL(random32_get_bytes); + +/** * random32 - pseudo random number generator * * A 32 bit pseudo-random number is generated using a fast -- 1.7.11.7
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