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1/* SPDX-License-Identifier: GPL-2.0-or-later */2/*3 * RNG: Random Number Generator algorithms under the crypto API4 *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_H10#define _CRYPTO_RNG_H11 12#include <linux/atomic.h>13#include <linux/container_of.h>14#include <linux/crypto.h>15 16struct crypto_rng;17 18/**19 * struct rng_alg - random number generator definition20 *21 * @generate: The function defined by this variable obtains a22 * random number. The random number generator transform23 * must generate the random number out of the context24 * provided with this call, plus any additional data25 * if provided to the call.26 * @seed: Seed or reseed the random number generator. With the27 * invocation of this function call, the random number28 * generator shall become ready for generation. If the29 * random number generator requires a seed for setting30 * up a new state, the seed must be provided by the31 * consumer while invoking this function. The required32 * size of the seed is defined with @seedsize .33 * @set_ent: Set entropy that would otherwise be obtained from34 * entropy source. Internal use only.35 * @seedsize: The seed size required for a random number generator36 * initialization defined with this variable. Some37 * random number generators does not require a seed38 * as the seeding is implemented internally without39 * 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 */43struct 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 56struct crypto_rng {57 struct crypto_tfm base;58};59 60extern struct crypto_rng *crypto_default_rng;61 62int crypto_get_default_rng(void);63void crypto_put_default_rng(void);64 65/**66 * DOC: Random number generator API67 *68 * The random number generator API is used with the ciphers of type69 * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto)70 */71 72/**73 * crypto_alloc_rng() -- allocate RNG handle74 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the75 * message digest cipher76 * @type: specifies the type of the cipher77 * @mask: specifies the mask for the cipher78 *79 * Allocate a cipher handle for a random number generator. The returned struct80 * crypto_rng is the cipher handle that is required for any subsequent81 * API invocation for that random number generator.82 *83 * For all random number generators, this call creates a new private copy of84 * the random number generator that does not share a state with other85 * instances. The only exception is the "krng" random number generator which86 * is a kernel crypto API use case for the get_random_bytes() function of the87 * /dev/random driver.88 *89 * Return: allocated cipher handle in case of success; IS_ERR() is true in case90 * of an error, PTR_ERR() returns the error code.91 */92struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask);93 94static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm)95{96 return &tfm->base;97}98 99static 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 RNG106 * @tfm: cipher handle107 *108 * Return the generic name (cra_name) of the initialized random number generator109 *110 * Return: generic name string111 */112static 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 handle119 * @tfm: cipher handle to be freed120 *121 * If @tfm is a NULL or error pointer, this function does nothing.122 */123static 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 number130 * @tfm: cipher handle131 * @src: Input buffer holding additional data, may be NULL132 * @slen: Length of additional data133 * @dst: output buffer holding the random numbers134 * @dlen: length of the output buffer135 *136 * This function fills the caller-allocated buffer with random137 * numbers using the random number generator referenced by the138 * cipher handle.139 *140 * Return: 0 function was successful; < 0 if an error occurred141 */142static 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 number151 * @tfm: cipher handle152 * @rdata: output buffer holding the random numbers153 * @dlen: length of the output buffer154 *155 * This function fills the caller-allocated buffer with random numbers using the156 * random number generator referenced by the cipher handle.157 *158 * Return: 0 function was successful; < 0 if an error occurred159 */160static 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 RNG168 * @tfm: cipher handle169 * @seed: seed input data170 * @slen: length of the seed input data171 *172 * The reset function completely re-initializes the random number generator173 * referenced by the cipher handle by clearing the current state. The new state174 * is initialized with the caller provided seed or automatically, depending175 * on the random number generator type (the ANSI X9.31 RNG requires176 * 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 seed178 * should have the length of the seed size defined for the random number179 * generator as defined by crypto_rng_seedsize.180 *181 * Return: 0 if the setting of the key was successful; < 0 if an error occurred182 */183int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,184 unsigned int slen);185 186/**187 * crypto_rng_seedsize() - obtain seed size of RNG188 * @tfm: cipher handle189 *190 * The function returns the seed size for the random number generator191 * referenced by the cipher handle. This value may be zero if the random192 * number generator does not implement or require a reseeding. For example,193 * the SP800-90A DRBGs implement an automated reseeding after reaching a194 * pre-defined threshold.195 *196 * Return: seed size for the random number generator197 */198static inline int crypto_rng_seedsize(struct crypto_rng *tfm)199{200 return crypto_rng_alg(tfm)->seedsize;201}202 203#endif204