include/crypto/rng.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * RNG: Random Number Generator  algorithms under the crypto API
   4  *
   5  * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
   6  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
   7  */
   8
   9 #ifndef _CRYPTO_RNG_H
  10 #define _CRYPTO_RNG_H
  11
  12 #include <linux/crypto.h>
  13
  14 struct crypto_rng;
  15
  16 /**
  17  * struct rng_alg - random number generator definition
  18  *
  19  * @generate:   The function defined by this variable obtains a
  20  *              random number. The random number generator transform
  21  *              must generate the random number out of the context
  22  *              provided with this call, plus any additional data
  23  *              if provided to the call.
  24  * @seed:       Seed or reseed the random number generator.  With the
  25  *              invocation of this function call, the random number
  26  *              generator shall become ready for generation.  If the
  27  *              random number generator requires a seed for setting
  28  *              up a new state, the seed must be provided by the
  29  *              consumer while invoking this function. The required
  30  *              size of the seed is defined with @seedsize .
  31  * @set_ent:    Set entropy that would otherwise be obtained from
  32  *              entropy source.  Internal use only.
  33  * @seedsize:   The seed size required for a random number generator
  34  *              initialization defined with this variable. Some
  35  *              random number generators does not require a seed
  36  *              as the seeding is implemented internally without
  37  *              the need of support by the consumer. In this case,
  38  *              the seed size is set to zero.
  39  * @base:       Common crypto API algorithm data structure.
  40  */
  41 struct rng_alg {
  42         int (*generate)(struct crypto_rng *tfm,
  43                         const u8 *src, unsigned int slen,
  44                         u8 *dst, unsigned int dlen);
  45         int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen);
  46         void (*set_ent)(struct crypto_rng *tfm, const u8 *data,
  47                         unsigned int len);
  48
  49         unsigned int seedsize;
  50
  51         struct crypto_alg base;
  52 };
  53
  54 struct crypto_rng {
  55         struct crypto_tfm base;
  56 };
  57
  58 extern struct crypto_rng *crypto_default_rng;
  59
  60 int crypto_get_default_rng(void);
  61 void crypto_put_default_rng(void);
  62
  63 /**
  64  * DOC: Random number generator API
  65  *
  66  * The random number generator API is used with the ciphers of type
  67  * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto)
  68  */
  69
  70 /**
  71  * crypto_alloc_rng() -- allocate RNG handle
  72  * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
  73  *            message digest cipher
  74  * @type: specifies the type of the cipher
  75  * @mask: specifies the mask for the cipher
  76  *
  77  * Allocate a cipher handle for a random number generator. The returned struct
  78  * crypto_rng is the cipher handle that is required for any subsequent
  79  * API invocation for that random number generator.
  80  *
  81  * For all random number generators, this call creates a new private copy of
  82  * the random number generator that does not share a state with other
  83  * instances. The only exception is the "krng" random number generator which
  84  * is a kernel crypto API use case for the get_random_bytes() function of the
  85  * /dev/random driver.
  86  *
  87  * Return: allocated cipher handle in case of success; IS_ERR() is true in case
  88  *         of an error, PTR_ERR() returns the error code.
  89  */
  90 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask);
  91
  92 static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm)
  93 {
  94         return &tfm->base;
  95 }
  96
  97 /**
  98  * crypto_rng_alg - obtain name of RNG
  99  * @tfm: cipher handle
 100  *
 101  * Return the generic name (cra_name) of the initialized random number generator
 102  *
 103  * Return: generic name string
 104  */
 105 static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm)
 106 {
 107         return container_of(crypto_rng_tfm(tfm)->__crt_alg,
 108                             struct rng_alg, base);
 109 }
 110
 111 /**
 112  * crypto_free_rng() - zeroize and free RNG handle
 113  * @tfm: cipher handle to be freed
 114  */
 115 static inline void crypto_free_rng(struct crypto_rng *tfm)
 116 {
 117         crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm));
 118 }
 119
 120 /**
 121  * crypto_rng_generate() - get random number
 122  * @tfm: cipher handle
 123  * @src: Input buffer holding additional data, may be NULL
 124  * @slen: Length of additional data
 125  * @dst: output buffer holding the random numbers
 126  * @dlen: length of the output buffer
 127  *
 128  * This function fills the caller-allocated buffer with random
 129  * numbers using the random number generator referenced by the
 130  * cipher handle.
 131  *
 132  * Return: 0 function was successful; < 0 if an error occurred
 133  */
 134 static inline int crypto_rng_generate(struct crypto_rng *tfm,
 135                                       const u8 *src, unsigned int slen,
 136                                       u8 *dst, unsigned int dlen)
 137 {
 138         struct crypto_alg *alg = tfm->base.__crt_alg;
 139         int ret;
 140
 141         crypto_stats_get(alg);
 142         ret = crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen);
 143         crypto_stats_rng_generate(alg, dlen, ret);
 144         return ret;
 145 }
 146
 147 /**
 148  * crypto_rng_get_bytes() - get random number
 149  * @tfm: cipher handle
 150  * @rdata: output buffer holding the random numbers
 151  * @dlen: length of the output buffer
 152  *
 153  * This function fills the caller-allocated buffer with random numbers using the
 154  * random number generator referenced by the cipher handle.
 155  *
 156  * Return: 0 function was successful; < 0 if an error occurred
 157  */
 158 static inline int crypto_rng_get_bytes(struct crypto_rng *tfm,
 159                                        u8 *rdata, unsigned int dlen)
 160 {
 161         return crypto_rng_generate(tfm, NULL, 0, rdata, dlen);
 162 }
 163
 164 /**
 165  * crypto_rng_reset() - re-initialize the RNG
 166  * @tfm: cipher handle
 167  * @seed: seed input data
 168  * @slen: length of the seed input data
 169  *
 170  * The reset function completely re-initializes the random number generator
 171  * referenced by the cipher handle by clearing the current state. The new state
 172  * is initialized with the caller provided seed or automatically, depending
 173  * on the random number generator type (the ANSI X9.31 RNG requires
 174  * caller-provided seed, the SP800-90A DRBGs perform an automatic seeding).
 175  * The seed is provided as a parameter to this function call. The provided seed
 176  * should have the length of the seed size defined for the random number
 177  * generator as defined by crypto_rng_seedsize.
 178  *
 179  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
 180  */
 181 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,
 182                      unsigned int slen);
 183
 184 /**
 185  * crypto_rng_seedsize() - obtain seed size of RNG
 186  * @tfm: cipher handle
 187  *
 188  * The function returns the seed size for the random number generator
 189  * referenced by the cipher handle. This value may be zero if the random
 190  * number generator does not implement or require a reseeding. For example,
 191  * the SP800-90A DRBGs implement an automated reseeding after reaching a
 192  * pre-defined threshold.
 193  *
 194  * Return: seed size for the random number generator
 195  */
 196 static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
 197 {
 198         return crypto_rng_alg(tfm)->seedsize;
 199 }
 200
 201 #endif