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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 0 : static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm) 93 : { 94 0 : 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 0 : static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm) 106 : { 107 0 : 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 0 : static inline void crypto_free_rng(struct crypto_rng *tfm) 116 : { 117 0 : 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 0 : 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 0 : struct crypto_alg *alg = tfm->base.__crt_alg; 139 0 : int ret; 140 : 141 0 : crypto_stats_get(alg); 142 0 : ret = crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen); 143 0 : crypto_stats_rng_generate(alg, dlen, ret); 144 0 : 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 0 : static inline int crypto_rng_get_bytes(struct crypto_rng *tfm, 159 : u8 *rdata, unsigned int dlen) 160 : { 161 0 : 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 0 : static inline int crypto_rng_seedsize(struct crypto_rng *tfm) 197 : { 198 0 : return crypto_rng_alg(tfm)->seedsize; 199 : } 200 : 201 : #endif
