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 * If @tfm is a NULL or error pointer, this function does nothing. 116 */ 117 static inline void crypto_free_rng(struct crypto_rng *tfm) 118 { 119 crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm)); 120 } 121 122 /** 123 * crypto_rng_generate() - get random number 124 * @tfm: cipher handle 125 * @src: Input buffer holding additional data, may be NULL 126 * @slen: Length of additional data 127 * @dst: output buffer holding the random numbers 128 * @dlen: length of the output buffer 129 * 130 * This function fills the caller-allocated buffer with random 131 * numbers using the random number generator referenced by the 132 * cipher handle. 133 * 134 * Return: 0 function was successful; < 0 if an error occurred 135 */ 136 static inline int crypto_rng_generate(struct crypto_rng *tfm, 137 const u8 *src, unsigned int slen, 138 u8 *dst, unsigned int dlen) 139 { 140 struct crypto_alg *alg = tfm->base.__crt_alg; 141 int ret; 142 143 crypto_stats_get(alg); 144 ret = crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen); 145 crypto_stats_rng_generate(alg, dlen, ret); 146 return ret; 147 } 148 149 /** 150 * crypto_rng_get_bytes() - get random number 151 * @tfm: cipher handle 152 * @rdata: output buffer holding the random numbers 153 * @dlen: length of the output buffer 154 * 155 * This function fills the caller-allocated buffer with random numbers using the 156 * random number generator referenced by the cipher handle. 157 * 158 * Return: 0 function was successful; < 0 if an error occurred 159 */ 160 static inline int crypto_rng_get_bytes(struct crypto_rng *tfm, 161 u8 *rdata, unsigned int dlen) 162 { 163 return crypto_rng_generate(tfm, NULL, 0, rdata, dlen); 164 } 165 166 /** 167 * crypto_rng_reset() - re-initialize the RNG 168 * @tfm: cipher handle 169 * @seed: seed input data 170 * @slen: length of the seed input data 171 * 172 * The reset function completely re-initializes the random number generator 173 * referenced by the cipher handle by clearing the current state. The new state 174 * is initialized with the caller provided seed or automatically, depending 175 * on the random number generator type (the ANSI X9.31 RNG requires 176 * caller-provided seed, the SP800-90A DRBGs perform an automatic seeding). 177 * The seed is provided as a parameter to this function call. The provided seed 178 * should have the length of the seed size defined for the random number 179 * generator as defined by crypto_rng_seedsize. 180 * 181 * Return: 0 if the setting of the key was successful; < 0 if an error occurred 182 */ 183 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, 184 unsigned int slen); 185 186 /** 187 * crypto_rng_seedsize() - obtain seed size of RNG 188 * @tfm: cipher handle 189 * 190 * The function returns the seed size for the random number generator 191 * referenced by the cipher handle. This value may be zero if the random 192 * number generator does not implement or require a reseeding. For example, 193 * the SP800-90A DRBGs implement an automated reseeding after reaching a 194 * pre-defined threshold. 195 * 196 * Return: seed size for the random number generator 197 */ 198 static inline int crypto_rng_seedsize(struct crypto_rng *tfm) 199 { 200 return crypto_rng_alg(tfm)->seedsize; 201 } 202 203 #endif 204