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 16struct crypto_rng; 17 18/* 19 * struct crypto_istat_rng: statistics for RNG algorithm 20 * @generate_cnt: number of RNG generate requests 21 * @generate_tlen: total data size of generated data by the RNG 22 * @seed_cnt: number of times the RNG was seeded 23 * @err_cnt: number of error for RNG requests 24 */ 25struct crypto_istat_rng { 26 atomic64_t generate_cnt; 27 atomic64_t generate_tlen; 28 atomic64_t seed_cnt; 29 atomic64_t err_cnt; 30}; 31 32/** 33 * struct rng_alg - random number generator definition 34 * 35 * @generate: The function defined by this variable obtains a 36 * random number. The random number generator transform 37 * must generate the random number out of the context 38 * provided with this call, plus any additional data 39 * if provided to the call. 40 * @seed: Seed or reseed the random number generator. With the 41 * invocation of this function call, the random number 42 * generator shall become ready for generation. If the 43 * random number generator requires a seed for setting 44 * up a new state, the seed must be provided by the 45 * consumer while invoking this function. The required 46 * size of the seed is defined with @seedsize . 47 * @set_ent: Set entropy that would otherwise be obtained from 48 * entropy source. Internal use only. 49 * @stat: Statistics for rng algorithm 50 * @seedsize: The seed size required for a random number generator 51 * initialization defined with this variable. Some 52 * random number generators does not require a seed 53 * as the seeding is implemented internally without 54 * the need of support by the consumer. In this case, 55 * the seed size is set to zero. 56 * @base: Common crypto API algorithm data structure. 57 */ 58struct rng_alg { 59 int (*generate)(struct crypto_rng *tfm, 60 const u8 *src, unsigned int slen, 61 u8 *dst, unsigned int dlen); 62 int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen); 63 void (*set_ent)(struct crypto_rng *tfm, const u8 *data, 64 unsigned int len); 65 66#ifdef CONFIG_CRYPTO_STATS 67 struct crypto_istat_rng stat; 68#endif 69 70 unsigned int seedsize; 71 72 struct crypto_alg base; 73}; 74 75struct crypto_rng { 76 struct crypto_tfm base; 77}; 78 79extern struct crypto_rng *crypto_default_rng; 80 81int crypto_get_default_rng(void); 82void crypto_put_default_rng(void); 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 */ 111struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask); 112 113static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm) 114{ 115 return &tfm->base; 116} 117 118static 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 name of RNG 125 * @tfm: cipher handle 126 * 127 * Return the generic name (cra_name) of the initialized random number generator 128 * 129 * Return: generic name string 130 */ 131static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm) 132{ 133 return __crypto_rng_alg(crypto_rng_tfm(tfm)->__crt_alg); 134} 135 136/** 137 * crypto_free_rng() - zeroize and free RNG handle 138 * @tfm: cipher handle to be freed 139 * 140 * If @tfm is a NULL or error pointer, this function does nothing. 141 */ 142static inline void crypto_free_rng(struct crypto_rng *tfm) 143{ 144 crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm)); 145} 146 147static inline struct crypto_istat_rng *rng_get_stat(struct rng_alg *alg) 148{ 149#ifdef CONFIG_CRYPTO_STATS 150 return &alg->stat; 151#else 152 return NULL; 153#endif 154} 155 156static inline int crypto_rng_errstat(struct rng_alg *alg, int err) 157{ 158 if (!IS_ENABLED(CONFIG_CRYPTO_STATS)) 159 return err; 160 161 if (err && err != -EINPROGRESS && err != -EBUSY) 162 atomic64_inc(&rng_get_stat(alg)->err_cnt); 163 164 return err; 165} 166 167/** 168 * crypto_rng_generate() - get random number 169 * @tfm: cipher handle 170 * @src: Input buffer holding additional data, may be NULL 171 * @slen: Length of additional data 172 * @dst: output buffer holding the random numbers 173 * @dlen: length of the output buffer 174 * 175 * This function fills the caller-allocated buffer with random 176 * numbers using the random number generator referenced by the 177 * cipher handle. 178 * 179 * Return: 0 function was successful; < 0 if an error occurred 180 */ 181static inline int crypto_rng_generate(struct crypto_rng *tfm, 182 const u8 *src, unsigned int slen, 183 u8 *dst, unsigned int dlen) 184{ 185 struct rng_alg *alg = crypto_rng_alg(tfm); 186 187 if (IS_ENABLED(CONFIG_CRYPTO_STATS)) { 188 struct crypto_istat_rng *istat = rng_get_stat(alg); 189 190 atomic64_inc(&istat->generate_cnt); 191 atomic64_add(dlen, &istat->generate_tlen); 192 } 193 194 return crypto_rng_errstat(alg, 195 alg->generate(tfm, src, slen, dst, dlen)); 196} 197 198/** 199 * crypto_rng_get_bytes() - get random number 200 * @tfm: cipher handle 201 * @rdata: output buffer holding the random numbers 202 * @dlen: length of the output buffer 203 * 204 * This function fills the caller-allocated buffer with random numbers using the 205 * random number generator referenced by the cipher handle. 206 * 207 * Return: 0 function was successful; < 0 if an error occurred 208 */ 209static inline int crypto_rng_get_bytes(struct crypto_rng *tfm, 210 u8 *rdata, unsigned int dlen) 211{ 212 return crypto_rng_generate(tfm, NULL, 0, rdata, dlen); 213} 214 215/** 216 * crypto_rng_reset() - re-initialize the RNG 217 * @tfm: cipher handle 218 * @seed: seed input data 219 * @slen: length of the seed input data 220 * 221 * The reset function completely re-initializes the random number generator 222 * referenced by the cipher handle by clearing the current state. The new state 223 * is initialized with the caller provided seed or automatically, depending 224 * on the random number generator type (the ANSI X9.31 RNG requires 225 * caller-provided seed, the SP800-90A DRBGs perform an automatic seeding). 226 * The seed is provided as a parameter to this function call. The provided seed 227 * should have the length of the seed size defined for the random number 228 * generator as defined by crypto_rng_seedsize. 229 * 230 * Return: 0 if the setting of the key was successful; < 0 if an error occurred 231 */ 232int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, 233 unsigned int slen); 234 235/** 236 * crypto_rng_seedsize() - obtain seed size of RNG 237 * @tfm: cipher handle 238 * 239 * The function returns the seed size for the random number generator 240 * referenced by the cipher handle. This value may be zero if the random 241 * number generator does not implement or require a reseeding. For example, 242 * the SP800-90A DRBGs implement an automated reseeding after reaching a 243 * pre-defined threshold. 244 * 245 * Return: seed size for the random number generator 246 */ 247static inline int crypto_rng_seedsize(struct crypto_rng *tfm) 248{ 249 return crypto_rng_alg(tfm)->seedsize; 250} 251 252#endif 253