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 #include <linux/fips.h> 16 #include <linux/random.h> 17 18 struct crypto_rng; 19 20 /** 21 * struct rng_alg - random number generator definition 22 * 23 * @generate: The function defined by this variable obtains a 24 * random number. The random number generator transform 25 * must generate the random number out of the context 26 * provided with this call, plus any additional data 27 * if provided to the call. 28 * @seed: Seed or reseed the random number generator. With the 29 * invocation of this function call, the random number 30 * generator shall become ready for generation. If the 31 * random number generator requires a seed for setting 32 * up a new state, the seed must be provided by the 33 * consumer while invoking this function. The required 34 * size of the seed is defined with @seedsize . 35 * @set_ent: Set entropy that would otherwise be obtained from 36 * entropy source. Internal use only. 37 * @seedsize: The seed size required for a random number generator 38 * initialization defined with this variable. Some 39 * random number generators does not require a seed 40 * as the seeding is implemented internally without 41 * the need of support by the consumer. In this case, 42 * the seed size is set to zero. 43 * @base: Common crypto API algorithm data structure. 44 */ 45 struct rng_alg { 46 int (*generate)(struct crypto_rng *tfm, 47 const u8 *src, unsigned int slen, 48 u8 *dst, unsigned int dlen); 49 int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen); 50 void (*set_ent)(struct crypto_rng *tfm, const u8 *data, 51 unsigned int len); 52 53 unsigned int seedsize; 54 55 struct crypto_alg base; 56 }; 57 58 struct crypto_rng { 59 struct crypto_tfm base; 60 }; 61 62 int __crypto_stdrng_get_bytes(void *buf, unsigned int len); 63 64 /** 65 * crypto_stdrng_get_bytes() - get cryptographically secure random bytes 66 * @buf: output buffer holding the random numbers 67 * @len: length of the output buffer 68 * 69 * This function fills the caller-allocated buffer with random numbers using the 70 * normal Linux RNG if fips_enabled=0, or the highest-priority "stdrng" 71 * algorithm in the crypto_rng subsystem if fips_enabled=1. 72 * 73 * Context: May sleep 74 * Return: 0 function was successful; < 0 if an error occurred 75 */ 76 static inline int crypto_stdrng_get_bytes(void *buf, unsigned int len) 77 { 78 might_sleep(); 79 if (fips_enabled) 80 return __crypto_stdrng_get_bytes(buf, len); 81 return get_random_bytes_wait(buf, len); 82 } 83 84 /** 85 * DOC: Random number generator API 86 * 87 * The random number generator API is used with the ciphers of type 88 * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto) 89 */ 90 91 /** 92 * crypto_alloc_rng() -- allocate RNG handle 93 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the 94 * message digest cipher 95 * @type: specifies the type of the cipher 96 * @mask: specifies the mask for the cipher 97 * 98 * Allocate a cipher handle for a random number generator. The returned struct 99 * crypto_rng is the cipher handle that is required for any subsequent 100 * API invocation for that random number generator. 101 * 102 * For all random number generators, this call creates a new private copy of 103 * the random number generator that does not share a state with other 104 * instances. The only exception is the "krng" random number generator which 105 * is a kernel crypto API use case for the get_random_bytes() function of the 106 * /dev/random driver. 107 * 108 * Return: allocated cipher handle in case of success; IS_ERR() is true in case 109 * of an error, PTR_ERR() returns the error code. 110 */ 111 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask); 112 113 static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm) 114 { 115 return &tfm->base; 116 } 117 118 static inline struct rng_alg *__crypto_rng_alg(struct crypto_alg *alg) 119 { 120 return container_of(alg, struct rng_alg, base); 121 } 122 123 /** 124 * crypto_rng_alg() - obtain 'struct rng_alg' pointer from RNG handle 125 * @tfm: RNG handle 126 * 127 * Return: Pointer to 'struct rng_alg', derived from @tfm RNG handle 128 */ 129 static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm) 130 { 131 return __crypto_rng_alg(crypto_rng_tfm(tfm)->__crt_alg); 132 } 133 134 /** 135 * crypto_free_rng() - zeroize and free RNG handle 136 * @tfm: cipher handle to be freed 137 * 138 * If @tfm is a NULL or error pointer, this function does nothing. 139 */ 140 static inline void crypto_free_rng(struct crypto_rng *tfm) 141 { 142 crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm)); 143 } 144 145 /** 146 * crypto_rng_generate() - get random number 147 * @tfm: cipher handle 148 * @src: Input buffer holding additional data, may be NULL 149 * @slen: Length of additional data 150 * @dst: output buffer holding the random numbers 151 * @dlen: length of the output buffer 152 * 153 * This function fills the caller-allocated buffer with random 154 * numbers using the random number generator referenced by the 155 * cipher handle. 156 * 157 * Return: 0 function was successful; < 0 if an error occurred 158 */ 159 static inline int crypto_rng_generate(struct crypto_rng *tfm, 160 const u8 *src, unsigned int slen, 161 u8 *dst, unsigned int dlen) 162 { 163 return crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen); 164 } 165 166 /** 167 * crypto_rng_get_bytes() - get random number 168 * @tfm: cipher handle 169 * @rdata: output buffer holding the random numbers 170 * @dlen: length of the output buffer 171 * 172 * This function fills the caller-allocated buffer with random numbers using the 173 * random number generator referenced by the cipher handle. 174 * 175 * Return: 0 function was successful; < 0 if an error occurred 176 */ 177 static inline int crypto_rng_get_bytes(struct crypto_rng *tfm, 178 u8 *rdata, unsigned int dlen) 179 { 180 return crypto_rng_generate(tfm, NULL, 0, rdata, dlen); 181 } 182 183 /** 184 * crypto_rng_reset() - re-initialize the RNG 185 * @tfm: cipher handle 186 * @seed: seed input data 187 * @slen: length of the seed input data 188 * 189 * The reset function completely re-initializes the random number generator 190 * referenced by the cipher handle by clearing the current state. The new state 191 * is initialized with the caller provided seed or automatically, depending on 192 * the random number generator type. (The SP800-90A DRBGs perform an automatic 193 * seeding.) The seed is provided as a parameter to this function call. The 194 * provided seed should have the length of the seed size defined for the random 195 * number generator as defined by crypto_rng_seedsize. 196 * 197 * Return: 0 if the setting of the key was successful; < 0 if an error occurred 198 */ 199 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, 200 unsigned int slen); 201 202 /** 203 * crypto_rng_seedsize() - obtain seed size of RNG 204 * @tfm: cipher handle 205 * 206 * The function returns the seed size for the random number generator 207 * referenced by the cipher handle. This value may be zero if the random 208 * number generator does not implement or require a reseeding. For example, 209 * the SP800-90A DRBGs implement an automated reseeding after reaching a 210 * pre-defined threshold. 211 * 212 * Return: seed size for the random number generator 213 */ 214 static inline int crypto_rng_seedsize(struct crypto_rng *tfm) 215 { 216 return crypto_rng_alg(tfm)->seedsize; 217 } 218 219 #endif 220