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(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(mem: 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, slen: 0, dst: 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
173 * on the random number generator type (the ANSI X9.31 RNG requires
174 * caller-provided seed, the SP800-90A DRBGs perform an automatic seeding).
175 * The seed is provided as a parameter to this function call. The provided seed
176 * should have the length of the seed size defined for the random number
177 * generator as defined by crypto_rng_seedsize.
178 *
179 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
180 */
181int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,
182 unsigned int slen);
183
184/**
185 * crypto_rng_seedsize() - obtain seed size of RNG
186 * @tfm: cipher handle
187 *
188 * The function returns the seed size for the random number generator
189 * referenced by the cipher handle. This value may be zero if the random
190 * number generator does not implement or require a reseeding. For example,
191 * the SP800-90A DRBGs implement an automated reseeding after reaching a
192 * pre-defined threshold.
193 *
194 * Return: seed size for the random number generator
195 */
196static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
197{
198 return crypto_rng_alg(tfm)->seedsize;
199}
200
201#endif
202