1 /*
2 * RNG: Random Number Generator algorithms under the crypto API
3 *
4 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
5 * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the Free
9 * Software Foundation; either version 2 of the License, or (at your option)
10 * any later version.
11 *
12 */
13
14 #ifndef _CRYPTO_RNG_H
15 #define _CRYPTO_RNG_H
16
17 #include <linux/crypto.h>
18
19 struct crypto_rng;
20
21 /**
22 * struct rng_alg - random number generator definition
23 *
24 * @generate: The function defined by this variable obtains a
25 * random number. The random number generator transform
26 * must generate the random number out of the context
27 * provided with this call, plus any additional data
28 * if provided to the call.
29 * @seed: Seed or reseed the random number generator. With the
30 * invocation of this function call, the random number
31 * generator shall become ready for generation. If the
32 * random number generator requires a seed for setting
33 * up a new state, the seed must be provided by the
34 * consumer while invoking this function. The required
35 * size of the seed is defined with @seedsize .
36 * @set_ent: Set entropy that would otherwise be obtained from
37 * entropy source. Internal use only.
38 * @seedsize: The seed size required for a random number generator
39 * initialization defined with this variable. Some
40 * random number generators does not require a seed
41 * as the seeding is implemented internally without
42 * the need of support by the consumer. In this case,
43 * the seed size is set to zero.
44 * @base: Common crypto API algorithm data structure.
45 */
46 struct rng_alg {
47 int (*generate)(struct crypto_rng *tfm,
48 const u8 *src, unsigned int slen,
49 u8 *dst, unsigned int dlen);
50 int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen);
51 void (*set_ent)(struct crypto_rng *tfm, const u8 *data,
52 unsigned int len);
53
54 unsigned int seedsize;
55
56 struct crypto_alg base;
57 };
58
59 struct crypto_rng {
60 struct crypto_tfm base;
61 };
62
63 extern struct crypto_rng *crypto_default_rng;
64
65 int crypto_get_default_rng(void);
66 void crypto_put_default_rng(void);
67
68 /**
69 * DOC: Random number generator API
70 *
71 * The random number generator API is used with the ciphers of type
72 * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto)
73 */
74
75 /**
76 * crypto_alloc_rng() -- allocate RNG handle
77 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
78 * message digest cipher
79 * @type: specifies the type of the cipher
80 * @mask: specifies the mask for the cipher
81 *
82 * Allocate a cipher handle for a random number generator. The returned struct
83 * crypto_rng is the cipher handle that is required for any subsequent
84 * API invocation for that random number generator.
85 *
86 * For all random number generators, this call creates a new private copy of
87 * the random number generator that does not share a state with other
88 * instances. The only exception is the "krng" random number generator which
89 * is a kernel crypto API use case for the get_random_bytes() function of the
90 * /dev/random driver.
91 *
92 * Return: allocated cipher handle in case of success; IS_ERR() is true in case
93 * of an error, PTR_ERR() returns the error code.
94 */
95 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask);
96
crypto_rng_tfm(struct crypto_rng * tfm)97 static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm)
98 {
99 return &tfm->base;
100 }
101
102 /**
103 * crypto_rng_alg - obtain name of RNG
104 * @tfm: cipher handle
105 *
106 * Return the generic name (cra_name) of the initialized random number generator
107 *
108 * Return: generic name string
109 */
crypto_rng_alg(struct crypto_rng * tfm)110 static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm)
111 {
112 return container_of(crypto_rng_tfm(tfm)->__crt_alg,
113 struct rng_alg, base);
114 }
115
116 /**
117 * crypto_free_rng() - zeroize and free RNG handle
118 * @tfm: cipher handle to be freed
119 *
120 * If @tfm is a NULL or error pointer, this function does nothing.
121 */
crypto_free_rng(struct crypto_rng * tfm)122 static inline void crypto_free_rng(struct crypto_rng *tfm)
123 {
124 crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm));
125 }
126
127 /**
128 * crypto_rng_generate() - get random number
129 * @tfm: cipher handle
130 * @src: Input buffer holding additional data, may be NULL
131 * @slen: Length of additional data
132 * @dst: output buffer holding the random numbers
133 * @dlen: length of the output buffer
134 *
135 * This function fills the caller-allocated buffer with random
136 * numbers using the random number generator referenced by the
137 * cipher handle.
138 *
139 * Return: 0 function was successful; < 0 if an error occurred
140 */
crypto_rng_generate(struct crypto_rng * tfm,const u8 * src,unsigned int slen,u8 * dst,unsigned int dlen)141 static inline int crypto_rng_generate(struct crypto_rng *tfm,
142 const u8 *src, unsigned int slen,
143 u8 *dst, unsigned int dlen)
144 {
145 return crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen);
146 }
147
148 /**
149 * crypto_rng_get_bytes() - get random number
150 * @tfm: cipher handle
151 * @rdata: output buffer holding the random numbers
152 * @dlen: length of the output buffer
153 *
154 * This function fills the caller-allocated buffer with random numbers using the
155 * random number generator referenced by the cipher handle.
156 *
157 * Return: 0 function was successful; < 0 if an error occurred
158 */
crypto_rng_get_bytes(struct crypto_rng * tfm,u8 * rdata,unsigned int dlen)159 static inline int crypto_rng_get_bytes(struct crypto_rng *tfm,
160 u8 *rdata, unsigned int dlen)
161 {
162 return crypto_rng_generate(tfm, NULL, 0, rdata, dlen);
163 }
164
165 /**
166 * crypto_rng_reset() - re-initialize the RNG
167 * @tfm: cipher handle
168 * @seed: seed input data
169 * @slen: length of the seed input data
170 *
171 * The reset function completely re-initializes the random number generator
172 * referenced by the cipher handle by clearing the current state. The new state
173 * is initialized with the caller provided seed or automatically, depending
174 * on the random number generator type (the ANSI X9.31 RNG requires
175 * caller-provided seed, the SP800-90A DRBGs perform an automatic seeding).
176 * The seed is provided as a parameter to this function call. The provided seed
177 * should have the length of the seed size defined for the random number
178 * generator as defined by crypto_rng_seedsize.
179 *
180 * Return: 0 if the setting of the key was successful; < 0 if an error occurred
181 */
182 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,
183 unsigned int slen);
184
185 /**
186 * crypto_rng_seedsize() - obtain seed size of RNG
187 * @tfm: cipher handle
188 *
189 * The function returns the seed size for the random number generator
190 * referenced by the cipher handle. This value may be zero if the random
191 * number generator does not implement or require a reseeding. For example,
192 * the SP800-90A DRBGs implement an automated reseeding after reaching a
193 * pre-defined threshold.
194 *
195 * Return: seed size for the random number generator
196 */
crypto_rng_seedsize(struct crypto_rng * tfm)197 static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
198 {
199 return crypto_rng_alg(tfm)->seedsize;
200 }
201
202 #endif
203