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/crypto.h>
13
14 struct crypto_rng;
15
16 /**
17 * struct rng_alg - random number generator definition
18 *
19 * @generate: The function defined by this variable obtains a
20 * random number. The random number generator transform
21 * must generate the random number out of the context
22 * provided with this call, plus any additional data
23 * if provided to the call.
24 * @seed: Seed or reseed the random number generator. With the
25 * invocation of this function call, the random number
26 * generator shall become ready for generation. If the
27 * random number generator requires a seed for setting
28 * up a new state, the seed must be provided by the
29 * consumer while invoking this function. The required
30 * size of the seed is defined with @seedsize .
31 * @set_ent: Set entropy that would otherwise be obtained from
32 * entropy source. Internal use only.
33 * @seedsize: The seed size required for a random number generator
34 * initialization defined with this variable. Some
35 * random number generators does not require a seed
36 * as the seeding is implemented internally without
37 * the need of support by the consumer. In this case,
38 * the seed size is set to zero.
39 * @base: Common crypto API algorithm data structure.
40 */
41 struct rng_alg {
42 int (*generate)(struct crypto_rng *tfm,
43 const u8 *src, unsigned int slen,
44 u8 *dst, unsigned int dlen);
45 int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen);
46 void (*set_ent)(struct crypto_rng *tfm, const u8 *data,
47 unsigned int len);
48
49 unsigned int seedsize;
50
51 struct crypto_alg base;
52 };
53
54 struct crypto_rng {
55 struct crypto_tfm base;
56 };
57
58 extern struct crypto_rng *crypto_default_rng;
59
60 int crypto_get_default_rng(void);
61 void crypto_put_default_rng(void);
62
63 /**
64 * DOC: Random number generator API
65 *
66 * The random number generator API is used with the ciphers of type
67 * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto)
68 */
69
70 /**
71 * crypto_alloc_rng() -- allocate RNG handle
72 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
73 * message digest cipher
74 * @type: specifies the type of the cipher
75 * @mask: specifies the mask for the cipher
76 *
77 * Allocate a cipher handle for a random number generator. The returned struct
78 * crypto_rng is the cipher handle that is required for any subsequent
79 * API invocation for that random number generator.
80 *
81 * For all random number generators, this call creates a new private copy of
82 * the random number generator that does not share a state with other
83 * instances. The only exception is the "krng" random number generator which
84 * is a kernel crypto API use case for the get_random_bytes() function of the
85 * /dev/random driver.
86 *
87 * Return: allocated cipher handle in case of success; IS_ERR() is true in case
88 * of an error, PTR_ERR() returns the error code.
89 */
90 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask);
91
92 static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm)
93 {
94 return &tfm->base;
95 }
96
97 /**
98 * crypto_rng_alg - obtain name of RNG
99 * @tfm: cipher handle
100 *
101 * Return the generic name (cra_name) of the initialized random number generator
102 *
103 * Return: generic name string
104 */
105 static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm)
106 {
107 return container_of(crypto_rng_tfm(tfm)->__crt_alg,
108 struct rng_alg, base);
109 }
110
111 /**
112 * crypto_free_rng() - zeroize and free RNG handle
113 * @tfm: cipher handle to be freed
114 */
115 static inline void crypto_free_rng(struct crypto_rng *tfm)
116 {
117 crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm));
118 }
119
120 /**
121 * crypto_rng_generate() - get random number
122 * @tfm: cipher handle
123 * @src: Input buffer holding additional data, may be NULL
124 * @slen: Length of additional data
125 * @dst: output buffer holding the random numbers
126 * @dlen: length of the output buffer
127 *
128 * This function fills the caller-allocated buffer with random
129 * numbers using the random number generator referenced by the
130 * cipher handle.
131 *
132 * Return: 0 function was successful; < 0 if an error occurred
133 */
134 static inline int crypto_rng_generate(struct crypto_rng *tfm,
135 const u8 *src, unsigned int slen,
136 u8 *dst, unsigned int dlen)
137 {
138 struct crypto_alg *alg = tfm->base.__crt_alg;
139 int ret;
140
141 crypto_stats_get(alg);
142 ret = crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen);
143 crypto_stats_rng_generate(alg, dlen, ret);
144 return ret;
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 */
158 static 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
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 */
181 int 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 */
196 static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
197 {
198 return crypto_rng_alg(tfm)->seedsize;
199 }
200
201 #endif