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Commit 6582c665d6b882dad8329e05749fbcf119f1ab88

Authored by Akinobu Mita
Committed by Linus Torvalds
1 parent 496f2f93b1
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

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>

Showing 2 changed files with 51 additions and 0 deletions Side-by-side Diff

include/linux/random.h
Diff comments   View file @ 6582c66
... ... @@ -26,6 +26,7 @@
26 26 unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len);
27 27  
28 28 u32 prandom_u32(void);
  29 +void prandom_bytes(void *buf, int nbytes);
29 30 void prandom_seed(u32 seed);
30 31  
31 32 /*
... ... @@ -36,6 +37,7 @@
36 37 #define srandom32(seed) prandom_seed(seed)
37 38  
38 39 u32 prandom_u32_state(struct rnd_state *);
  40 +void prandom_bytes_state(struct rnd_state *state, void *buf, int nbytes);
39 41  
40 42 /*
41 43 * Handle minimum values for seeds
... ... @@ -77,6 +77,55 @@
77 77 }
78 78 EXPORT_SYMBOL(prandom_u32);
79 79  
  80 +/*
  81 + * prandom_bytes_state - get the requested number of pseudo-random bytes
  82 + *
  83 + * @state: pointer to state structure holding seeded state.
  84 + * @buf: where to copy the pseudo-random bytes to
  85 + * @bytes: the requested number of bytes
  86 + *
  87 + * This is used for pseudo-randomness with no outside seeding.
  88 + * For more random results, use prandom_bytes().
  89 + */
  90 +void prandom_bytes_state(struct rnd_state *state, void *buf, int bytes)
  91 +{
  92 + unsigned char *p = buf;
  93 + int i;
  94 +
  95 + for (i = 0; i < round_down(bytes, sizeof(u32)); i += sizeof(u32)) {
  96 + u32 random = prandom_u32_state(state);
  97 + int j;
  98 +
  99 + for (j = 0; j < sizeof(u32); j++) {
  100 + p[i + j] = random;
  101 + random >>= BITS_PER_BYTE;
  102 + }
  103 + }
  104 + if (i < bytes) {
  105 + u32 random = prandom_u32_state(state);
  106 +
  107 + for (; i < bytes; i++) {
  108 + p[i] = random;
  109 + random >>= BITS_PER_BYTE;
  110 + }
  111 + }
  112 +}
  113 +EXPORT_SYMBOL(prandom_bytes_state);
  114 +
  115 +/**
  116 + * prandom_bytes - get the requested number of pseudo-random bytes
  117 + * @buf: where to copy the pseudo-random bytes to
  118 + * @bytes: the requested number of bytes
  119 + */
  120 +void prandom_bytes(void *buf, int bytes)
  121 +{
  122 + struct rnd_state *state = &get_cpu_var(net_rand_state);
  123 +
  124 + prandom_bytes_state(state, buf, bytes);
  125 + put_cpu_var(state);
  126 +}
  127 +EXPORT_SYMBOL(prandom_bytes);
  128 +
80 129 /**
81 130 * prandom_seed - add entropy to pseudo random number generator
82 131 * @seed: seed value