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 
crypto_rng_tfm(struct crypto_rng * tfm)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  */
crypto_rng_alg(struct crypto_rng * tfm)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  * If @tfm is a NULL or error pointer, this function does nothing.
116  */
crypto_free_rng(struct crypto_rng * tfm)117 static inline void crypto_free_rng(struct crypto_rng *tfm)
118 {
119 	crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm));
120 }
121 
122 /**
123  * crypto_rng_generate() - get random number
124  * @tfm: cipher handle
125  * @src: Input buffer holding additional data, may be NULL
126  * @slen: Length of additional data
127  * @dst: output buffer holding the random numbers
128  * @dlen: length of the output buffer
129  *
130  * This function fills the caller-allocated buffer with random
131  * numbers using the random number generator referenced by the
132  * cipher handle.
133  *
134  * Return: 0 function was successful; < 0 if an error occurred
135  */
crypto_rng_generate(struct crypto_rng * tfm,const u8 * src,unsigned int slen,u8 * dst,unsigned int dlen)136 static inline int crypto_rng_generate(struct crypto_rng *tfm,
137 				      const u8 *src, unsigned int slen,
138 				      u8 *dst, unsigned int dlen)
139 {
140 	struct crypto_alg *alg = tfm->base.__crt_alg;
141 	int ret;
142 
143 	crypto_stats_get(alg);
144 	ret = crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen);
145 	crypto_stats_rng_generate(alg, dlen, ret);
146 	return ret;
147 }
148 
149 /**
150  * crypto_rng_get_bytes() - get random number
151  * @tfm: cipher handle
152  * @rdata: output buffer holding the random numbers
153  * @dlen: length of the output buffer
154  *
155  * This function fills the caller-allocated buffer with random numbers using the
156  * random number generator referenced by the cipher handle.
157  *
158  * Return: 0 function was successful; < 0 if an error occurred
159  */
crypto_rng_get_bytes(struct crypto_rng * tfm,u8 * rdata,unsigned int dlen)160 static 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 RNG
168  * @tfm: cipher handle
169  * @seed: seed input data
170  * @slen: length of the seed input data
171  *
172  * The reset function completely re-initializes the random number generator
173  * referenced by the cipher handle by clearing the current state. The new state
174  * is initialized with the caller provided seed or automatically, depending
175  * on the random number generator type (the ANSI X9.31 RNG requires
176  * 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 seed
178  * should have the length of the seed size defined for the random number
179  * generator as defined by crypto_rng_seedsize.
180  *
181  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
182  */
183 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,
184 		     unsigned int slen);
185 
186 /**
187  * crypto_rng_seedsize() - obtain seed size of RNG
188  * @tfm: cipher handle
189  *
190  * The function returns the seed size for the random number generator
191  * referenced by the cipher handle. This value may be zero if the random
192  * number generator does not implement or require a reseeding. For example,
193  * the SP800-90A DRBGs implement an automated reseeding after reaching a
194  * pre-defined threshold.
195  *
196  * Return: seed size for the random number generator
197  */
crypto_rng_seedsize(struct crypto_rng * tfm)198 static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
199 {
200 	return crypto_rng_alg(tfm)->seedsize;
201 }
202 
203 #endif
204