prandom: introduce prandom_bytes() and prandom_bytes_state()
Add functions to get the requested number of pseudo-random bytes. The difference from get_random_bytes() is that it generates pseudo-random numbers by prandom_u32(). It doesn't consume the entropy pool, and the sequence is reproducible if the same rnd_state is used. So it is suitable for generating random bytes for testing. 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: Eilon Greenstein <eilong@broadcom.com> Cc: David Laight <david.laight@aculab.com> Cc: Michel Lespinasse <walken@google.com> Cc: Robert Love <robert.w.love@intel.com> Cc: Valdis Kletnieks <valdis.kletnieks@vt.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -26,6 +26,7 @@ unsigned int get_random_int(void);
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unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len);
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u32 prandom_u32(void);
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void prandom_bytes(void *buf, int nbytes);
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void prandom_seed(u32 seed);
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/*
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@ -36,6 +37,7 @@ void prandom_seed(u32 seed);
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#define srandom32(seed) prandom_seed(seed)
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u32 prandom_u32_state(struct rnd_state *);
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void prandom_bytes_state(struct rnd_state *state, void *buf, int nbytes);
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/*
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* Handle minimum values for seeds
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@ -77,6 +77,55 @@ u32 prandom_u32(void)
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}
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EXPORT_SYMBOL(prandom_u32);
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/*
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* prandom_bytes_state - get the requested number of pseudo-random bytes
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*
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* @state: pointer to state structure holding seeded state.
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* @buf: where to copy the pseudo-random bytes to
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* @bytes: the requested number of bytes
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*
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* This is used for pseudo-randomness with no outside seeding.
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* For more random results, use prandom_bytes().
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*/
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void prandom_bytes_state(struct rnd_state *state, void *buf, int bytes)
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{
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unsigned char *p = buf;
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int i;
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for (i = 0; i < round_down(bytes, sizeof(u32)); i += sizeof(u32)) {
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u32 random = prandom_u32_state(state);
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int j;
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for (j = 0; j < sizeof(u32); j++) {
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p[i + j] = random;
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random >>= BITS_PER_BYTE;
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}
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}
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if (i < bytes) {
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u32 random = prandom_u32_state(state);
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for (; i < bytes; i++) {
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p[i] = random;
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random >>= BITS_PER_BYTE;
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}
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}
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}
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EXPORT_SYMBOL(prandom_bytes_state);
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/**
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* prandom_bytes - get the requested number of pseudo-random bytes
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* @buf: where to copy the pseudo-random bytes to
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* @bytes: the requested number of bytes
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*/
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void prandom_bytes(void *buf, int bytes)
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{
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struct rnd_state *state = &get_cpu_var(net_rand_state);
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prandom_bytes_state(state, buf, bytes);
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put_cpu_var(state);
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}
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EXPORT_SYMBOL(prandom_bytes);
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/**
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* prandom_seed - add entropy to pseudo random number generator
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* @seed: seed value
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