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 * crypto_stdrng_get_bytes() - get cryptographically secure random bytes 67 * @buf: output buffer holding the random numbers 68 * @len: length of the output buffer 69 * 70 * This function fills the caller-allocated buffer with random numbers using the 71 * highest-priority "stdrng" algorithm in the crypto_rng subsystem. 72 * 73 * Context: May sleep 74 * Return: 0 function was successful; < 0 if an error occurred 75 */ 76 int crypto_stdrng_get_bytes(void *buf, unsigned int len); 77 78 /** 79 * DOC: Random number generator API 80 * 81 * The random number generator API is used with the ciphers of type 82 * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto) 83 */ 84 85 /** 86 * crypto_alloc_rng() -- allocate RNG handle 87 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the 88 * message digest cipher 89 * @type: specifies the type of the cipher 90 * @mask: specifies the mask for the cipher 91 * 92 * Allocate a cipher handle for a random number generator. The returned struct 93 * crypto_rng is the cipher handle that is required for any subsequent 94 * API invocation for that random number generator. 95 * 96 * For all random number generators, this call creates a new private copy of 97 * the random number generator that does not share a state with other 98 * instances. The only exception is the "krng" random number generator which 99 * is a kernel crypto API use case for the get_random_bytes() function of the 100 * /dev/random driver. 101 * 102 * Return: allocated cipher handle in case of success; IS_ERR() is true in case 103 * of an error, PTR_ERR() returns the error code. 104 */ 105 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask); 106 107 static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm) 108 { 109 return &tfm->base; 110 } 111 112 static inline struct rng_alg *__crypto_rng_alg(struct crypto_alg *alg) 113 { 114 return container_of(alg, struct rng_alg, base); 115 } 116 117 /** 118 * crypto_rng_alg() - obtain 'struct rng_alg' pointer from RNG handle 119 * @tfm: RNG handle 120 * 121 * Return: Pointer to 'struct rng_alg', derived from @tfm RNG handle 122 */ 123 static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm) 124 { 125 return __crypto_rng_alg(crypto_rng_tfm(tfm)->__crt_alg); 126 } 127 128 /** 129 * crypto_free_rng() - zeroize and free RNG handle 130 * @tfm: cipher handle to be freed 131 * 132 * If @tfm is a NULL or error pointer, this function does nothing. 133 */ 134 static inline void crypto_free_rng(struct crypto_rng *tfm) 135 { 136 crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm)); 137 } 138 139 /** 140 * crypto_rng_generate() - get random number 141 * @tfm: cipher handle 142 * @src: Input buffer holding additional data, may be NULL 143 * @slen: Length of additional data 144 * @dst: output buffer holding the random numbers 145 * @dlen: length of the output buffer 146 * 147 * This function fills the caller-allocated buffer with random 148 * numbers using the random number generator referenced by the 149 * cipher handle. 150 * 151 * Return: 0 function was successful; < 0 if an error occurred 152 */ 153 static inline int crypto_rng_generate(struct crypto_rng *tfm, 154 const u8 *src, unsigned int slen, 155 u8 *dst, unsigned int dlen) 156 { 157 return crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen); 158 } 159 160 /** 161 * crypto_rng_get_bytes() - get random number 162 * @tfm: cipher handle 163 * @rdata: output buffer holding the random numbers 164 * @dlen: length of the output buffer 165 * 166 * This function fills the caller-allocated buffer with random numbers using the 167 * random number generator referenced by the cipher handle. 168 * 169 * Return: 0 function was successful; < 0 if an error occurred 170 */ 171 static inline int crypto_rng_get_bytes(struct crypto_rng *tfm, 172 u8 *rdata, unsigned int dlen) 173 { 174 return crypto_rng_generate(tfm, NULL, 0, rdata, dlen); 175 } 176 177 /** 178 * crypto_rng_reset() - re-initialize the RNG 179 * @tfm: cipher handle 180 * @seed: seed input data 181 * @slen: length of the seed input data 182 * 183 * The reset function completely re-initializes the random number generator 184 * referenced by the cipher handle by clearing the current state. The new state 185 * is initialized with the caller provided seed or automatically, depending on 186 * the random number generator type. (The SP800-90A DRBGs perform an automatic 187 * seeding.) The seed is provided as a parameter to this function call. The 188 * provided seed should have the length of the seed size defined for the random 189 * number generator as defined by crypto_rng_seedsize. 190 * 191 * Return: 0 if the setting of the key was successful; < 0 if an error occurred 192 */ 193 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, 194 unsigned int slen); 195 196 /** 197 * crypto_rng_seedsize() - obtain seed size of RNG 198 * @tfm: cipher handle 199 * 200 * The function returns the seed size for the random number generator 201 * referenced by the cipher handle. This value may be zero if the random 202 * number generator does not implement or require a reseeding. For example, 203 * the SP800-90A DRBGs implement an automated reseeding after reaching a 204 * pre-defined threshold. 205 * 206 * Return: seed size for the random number generator 207 */ 208 static inline int crypto_rng_seedsize(struct crypto_rng *tfm) 209 { 210 return crypto_rng_alg(tfm)->seedsize; 211 } 212 213 #endif 214