include/crypto/rng.h

   1 /*
   2  * RNG: Random Number Generator  algorithms under the crypto API
   3  *
   4  * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
   5  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the Free
   9  * Software Foundation; either version 2 of the License, or (at your option)
  10  * any later version.
  11  *
  12  */
  13
  14 #ifndef _CRYPTO_RNG_H
  15 #define _CRYPTO_RNG_H
  16
  17 #include <linux/crypto.h>
  18
  19 struct crypto_rng;
  20
  21 /**
  22  * struct rng_alg - random number generator definition
  23  *
  24  * @generate:   The function defined by this variable obtains a
  25  *              random number. The random number generator transform
  26  *              must generate the random number out of the context
  27  *              provided with this call, plus any additional data
  28  *              if provided to the call.
  29  * @seed:       Seed or reseed the random number generator.  With the
  30  *              invocation of this function call, the random number
  31  *              generator shall become ready for generation.  If the
  32  *              random number generator requires a seed for setting
  33  *              up a new state, the seed must be provided by the
  34  *              consumer while invoking this function. The required
  35  *              size of the seed is defined with @seedsize .
  36  * @set_ent:    Set entropy that would otherwise be obtained from
  37  *              entropy source.  Internal use only.
  38  * @seedsize:   The seed size required for a random number generator
  39  *              initialization defined with this variable. Some
  40  *              random number generators does not require a seed
  41  *              as the seeding is implemented internally without
  42  *              the need of support by the consumer. In this case,
  43  *              the seed size is set to zero.
  44  * @base:       Common crypto API algorithm data structure.
  45  */
  46 struct rng_alg {
  47         int (*generate)(struct crypto_rng *tfm,
  48                         const u8 *src, unsigned int slen,
  49                         u8 *dst, unsigned int dlen);
  50         int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen);
  51         void (*set_ent)(struct crypto_rng *tfm, const u8 *data,
  52                         unsigned int len);
  53
  54         unsigned int seedsize;
  55
  56         struct crypto_alg base;
  57 };
  58
  59 struct crypto_rng {
  60         struct crypto_tfm base;
  61 };
  62
  63 extern struct crypto_rng *crypto_default_rng;
  64
  65 int crypto_get_default_rng(void);
  66 void crypto_put_default_rng(void);
  67
  68 /**
  69  * DOC: Random number generator API
  70  *
  71  * The random number generator API is used with the ciphers of type
  72  * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto)
  73  */
  74
  75 /**
  76  * crypto_alloc_rng() -- allocate RNG handle
  77  * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
  78  *            message digest cipher
  79  * @type: specifies the type of the cipher
  80  * @mask: specifies the mask for the cipher
  81  *
  82  * Allocate a cipher handle for a random number generator. The returned struct
  83  * crypto_rng is the cipher handle that is required for any subsequent
  84  * API invocation for that random number generator.
  85  *
  86  * For all random number generators, this call creates a new private copy of
  87  * the random number generator that does not share a state with other
  88  * instances. The only exception is the "krng" random number generator which
  89  * is a kernel crypto API use case for the get_random_bytes() function of the
  90  * /dev/random driver.
  91  *
  92  * Return: allocated cipher handle in case of success; IS_ERR() is true in case
  93  *         of an error, PTR_ERR() returns the error code.
  94  */
  95 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask);
  96
  97 static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm)
  98 {
  99         return &tfm->base;
 100 }
 101
 102 /**
 103  * crypto_rng_alg - obtain name of RNG
 104  * @tfm: cipher handle
 105  *
 106  * Return the generic name (cra_name) of the initialized random number generator
 107  *
 108  * Return: generic name string
 109  */
 110 static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm)
 111 {
 112         return container_of(crypto_rng_tfm(tfm)->__crt_alg,
 113                             struct rng_alg, base);
 114 }
 115
 116 /**
 117  * crypto_free_rng() - zeroize and free RNG handle
 118  * @tfm: cipher handle to be freed
 119  */
 120 static inline void crypto_free_rng(struct crypto_rng *tfm)
 121 {
 122         crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm));
 123 }
 124
 125 /**
 126  * crypto_rng_generate() - get random number
 127  * @tfm: cipher handle
 128  * @src: Input buffer holding additional data, may be NULL
 129  * @slen: Length of additional data
 130  * @dst: output buffer holding the random numbers
 131  * @dlen: length of the output buffer
 132  *
 133  * This function fills the caller-allocated buffer with random
 134  * numbers using the random number generator referenced by the
 135  * cipher handle.
 136  *
 137  * Return: 0 function was successful; < 0 if an error occurred
 138  */
 139 static inline int crypto_rng_generate(struct crypto_rng *tfm,
 140                                       const u8 *src, unsigned int slen,
 141                                       u8 *dst, unsigned int dlen)
 142 {
 143         struct crypto_alg *alg = tfm->base.__crt_alg;
 144         int ret;
 145
 146         crypto_stats_get(alg);
 147         ret = crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen);
 148         crypto_stats_rng_generate(alg, dlen, ret);
 149         return ret;
 150 }
 151
 152 /**
 153  * crypto_rng_get_bytes() - get random number
 154  * @tfm: cipher handle
 155  * @rdata: output buffer holding the random numbers
 156  * @dlen: length of the output buffer
 157  *
 158  * This function fills the caller-allocated buffer with random numbers using the
 159  * random number generator referenced by the cipher handle.
 160  *
 161  * Return: 0 function was successful; < 0 if an error occurred
 162  */
 163 static inline int crypto_rng_get_bytes(struct crypto_rng *tfm,
 164                                        u8 *rdata, unsigned int dlen)
 165 {
 166         return crypto_rng_generate(tfm, NULL, 0, rdata, dlen);
 167 }
 168
 169 /**
 170  * crypto_rng_reset() - re-initialize the RNG
 171  * @tfm: cipher handle
 172  * @seed: seed input data
 173  * @slen: length of the seed input data
 174  *
 175  * The reset function completely re-initializes the random number generator
 176  * referenced by the cipher handle by clearing the current state. The new state
 177  * is initialized with the caller provided seed or automatically, depending
 178  * on the random number generator type (the ANSI X9.31 RNG requires
 179  * caller-provided seed, the SP800-90A DRBGs perform an automatic seeding).
 180  * The seed is provided as a parameter to this function call. The provided seed
 181  * should have the length of the seed size defined for the random number
 182  * generator as defined by crypto_rng_seedsize.
 183  *
 184  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
 185  */
 186 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,
 187                      unsigned int slen);
 188
 189 /**
 190  * crypto_rng_seedsize() - obtain seed size of RNG
 191  * @tfm: cipher handle
 192  *
 193  * The function returns the seed size for the random number generator
 194  * referenced by the cipher handle. This value may be zero if the random
 195  * number generator does not implement or require a reseeding. For example,
 196  * the SP800-90A DRBGs implement an automated reseeding after reaching a
 197  * pre-defined threshold.
 198  *
 199  * Return: seed size for the random number generator
 200  */
 201 static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
 202 {
 203         return crypto_rng_alg(tfm)->seedsize;
 204 }
 205
 206 #endif