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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