rng.h

  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 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 */
 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 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 */
 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 'struct rng_alg' pointer from RNG handle
106 * @tfm: RNG handle
107 *
108 * Return: Pointer to 'struct rng_alg', derived from @tfm RNG handle
109 */
110static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm)
111{
112	return __crypto_rng_alg(crypto_rng_tfm(tfm)->__crt_alg);
113}
114
115/**
116 * crypto_free_rng() - zeroize and free RNG handle
117 * @tfm: cipher handle to be freed
118 *
119 * If @tfm is a NULL or error pointer, this function does nothing.
120 */
121static inline void crypto_free_rng(struct crypto_rng *tfm)
122{
123	crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm));
124}
125
126/**
127 * crypto_rng_generate() - get random number
128 * @tfm: cipher handle
129 * @src: Input buffer holding additional data, may be NULL
130 * @slen: Length of additional data
131 * @dst: output buffer holding the random numbers
132 * @dlen: length of the output buffer
133 *
134 * This function fills the caller-allocated buffer with random
135 * numbers using the random number generator referenced by the
136 * cipher handle.
137 *
138 * Return: 0 function was successful; < 0 if an error occurred
139 */
140static inline int crypto_rng_generate(struct crypto_rng *tfm,
141				      const u8 *src, unsigned int slen,
142				      u8 *dst, unsigned int dlen)
143{
144	return crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen);
145}
146
147/**
148 * crypto_rng_get_bytes() - get random number
149 * @tfm: cipher handle
150 * @rdata: output buffer holding the random numbers
151 * @dlen: length of the output buffer
152 *
153 * This function fills the caller-allocated buffer with random numbers using the
154 * random number generator referenced by the cipher handle.
155 *
156 * Return: 0 function was successful; < 0 if an error occurred
157 */
158static inline int crypto_rng_get_bytes(struct crypto_rng *tfm,
159				       u8 *rdata, unsigned int dlen)
160{
161	return crypto_rng_generate(tfm, NULL, 0, rdata, dlen);
162}
163
164/**
165 * crypto_rng_reset() - re-initialize the RNG
166 * @tfm: cipher handle
167 * @seed: seed input data
168 * @slen: length of the seed input data
169 *
170 * The reset function completely re-initializes the random number generator
171 * referenced by the cipher handle by clearing the current state. The new state
172 * is initialized with the caller provided seed or automatically, depending on
173 * the random number generator type. (The SP800-90A DRBGs perform an automatic
174 * seeding.) The seed is provided as a parameter to this function call. The
175 * provided seed should have the length of the seed size defined for the random
176 * number generator as defined by crypto_rng_seedsize.
177 *
178 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
179 */
180int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,
181		     unsigned int slen);
182
183/**
184 * crypto_rng_seedsize() - obtain seed size of RNG
185 * @tfm: cipher handle
186 *
187 * The function returns the seed size for the random number generator
188 * referenced by the cipher handle. This value may be zero if the random
189 * number generator does not implement or require a reseeding. For example,
190 * the SP800-90A DRBGs implement an automated reseeding after reaching a
191 * pre-defined threshold.
192 *
193 * Return: seed size for the random number generator
194 */
195static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
196{
197	return crypto_rng_alg(tfm)->seedsize;
198}
199
200#endif