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/atomic.h> 13 #include <linux/container_of.h> 14 #include <linux/crypto.h> 15 16 struct crypto_rng; 17 18 /** 19 * struct rng_alg - random number generator definition 20 * 21 * @generate: The function defined by this variable obtains a 22 * random number. The random number generator transform 23 * must generate the random number out of the context 24 * provided with this call, plus any additional data 25 * if provided to the call. 26 * @seed: Seed or reseed the random number generator. With the 27 * invocation of this function call, the random number 28 * generator shall become ready for generation. If the 29 * random number generator requires a seed for setting 30 * up a new state, the seed must be provided by the 31 * consumer while invoking this function. The required 32 * size of the seed is defined with @seedsize . 33 * @set_ent: Set entropy that would otherwise be obtained from 34 * entropy source. Internal use only. 35 * @seedsize: The seed size required for a random number generator 36 * initialization defined with this variable. Some 37 * random number generators does not require a seed 38 * as the seeding is implemented internally without 39 * the need of support by the consumer. In this case, 40 * the seed size is set to zero. 41 * @base: Common crypto API algorithm data structure. 42 */ 43 struct rng_alg { 44 int (*generate)(struct crypto_rng *tfm, 45 const u8 *src, unsigned int slen, 46 u8 *dst, unsigned int dlen); 47 int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen); 48 void (*set_ent)(struct crypto_rng *tfm, const u8 *data, 49 unsigned int len); 50 51 unsigned int seedsize; 52 53 struct crypto_alg base; 54 }; 55 56 struct crypto_rng { 57 struct crypto_tfm base; 58 }; 59 60 extern struct crypto_rng *crypto_default_rng; 61 62 int crypto_get_default_rng(void); 63 void crypto_put_default_rng(void); 64 65 /** 66 * DOC: Random number generator API 67 * 68 * The random number generator API is used with the ciphers of type 69 * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto) 70 */ 71 72 /** 73 * crypto_alloc_rng() -- allocate RNG handle 74 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the 75 * message digest cipher 76 * @type: specifies the type of the cipher 77 * @mask: specifies the mask for the cipher 78 * 79 * Allocate a cipher handle for a random number generator. The returned struct 80 * crypto_rng is the cipher handle that is required for any subsequent 81 * API invocation for that random number generator. 82 * 83 * For all random number generators, this call creates a new private copy of 84 * the random number generator that does not share a state with other 85 * instances. The only exception is the "krng" random number generator which 86 * is a kernel crypto API use case for the get_random_bytes() function of the 87 * /dev/random driver. 88 * 89 * Return: allocated cipher handle in case of success; IS_ERR() is true in case 90 * of an error, PTR_ERR() returns the error code. 91 */ 92 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask); 93 94 static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm) 95 { 96 return &tfm->base; 97 } 98 99 static inline struct rng_alg *__crypto_rng_alg(struct crypto_alg *alg) 100 { 101 return container_of(alg, struct rng_alg, base); 102 } 103 104 /** 105 * crypto_rng_alg - obtain name of RNG 106 * @tfm: cipher handle 107 * 108 * Return the generic name (cra_name) of the initialized random number generator 109 * 110 * Return: generic name string 111 */ 112 static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm) 113 { 114 return __crypto_rng_alg(crypto_rng_tfm(tfm)->__crt_alg); 115 } 116 117 /** 118 * crypto_free_rng() - zeroize and free RNG handle 119 * @tfm: cipher handle to be freed 120 * 121 * If @tfm is a NULL or error pointer, this function does nothing. 122 */ 123 static inline void crypto_free_rng(struct crypto_rng *tfm) 124 { 125 crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm)); 126 } 127 128 /** 129 * crypto_rng_generate() - get random number 130 * @tfm: cipher handle 131 * @src: Input buffer holding additional data, may be NULL 132 * @slen: Length of additional data 133 * @dst: output buffer holding the random numbers 134 * @dlen: length of the output buffer 135 * 136 * This function fills the caller-allocated buffer with random 137 * numbers using the random number generator referenced by the 138 * cipher handle. 139 * 140 * Return: 0 function was successful; < 0 if an error occurred 141 */ 142 static inline int crypto_rng_generate(struct crypto_rng *tfm, 143 const u8 *src, unsigned int slen, 144 u8 *dst, unsigned int dlen) 145 { 146 return crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen); 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