xref: /linux/crypto/rng.c (revision b85d45947951d23cb22d90caecf4c1eb81342c96)
1 /*
2  * Cryptographic API.
3  *
4  * RNG operations.
5  *
6  * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
7  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
8  *
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU General Public License as published by the Free
11  * Software Foundation; either version 2 of the License, or (at your option)
12  * any later version.
13  *
14  */
15 
16 #include <linux/atomic.h>
17 #include <crypto/internal/rng.h>
18 #include <linux/err.h>
19 #include <linux/module.h>
20 #include <linux/mutex.h>
21 #include <linux/random.h>
22 #include <linux/seq_file.h>
23 #include <linux/slab.h>
24 #include <linux/string.h>
25 #include <linux/cryptouser.h>
26 #include <net/netlink.h>
27 
28 #include "internal.h"
29 
30 static DEFINE_MUTEX(crypto_default_rng_lock);
31 struct crypto_rng *crypto_default_rng;
32 EXPORT_SYMBOL_GPL(crypto_default_rng);
33 static int crypto_default_rng_refcnt;
34 
35 static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm)
36 {
37 	return container_of(tfm, struct crypto_rng, base);
38 }
39 
40 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
41 {
42 	u8 *buf = NULL;
43 	int err;
44 
45 	if (!seed && slen) {
46 		buf = kmalloc(slen, GFP_KERNEL);
47 		if (!buf)
48 			return -ENOMEM;
49 
50 		get_random_bytes(buf, slen);
51 		seed = buf;
52 	}
53 
54 	err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
55 
56 	kzfree(buf);
57 	return err;
58 }
59 EXPORT_SYMBOL_GPL(crypto_rng_reset);
60 
61 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
62 {
63 	return 0;
64 }
65 
66 static unsigned int seedsize(struct crypto_alg *alg)
67 {
68 	struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
69 
70 	return ralg->seedsize;
71 }
72 
73 #ifdef CONFIG_NET
74 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
75 {
76 	struct crypto_report_rng rrng;
77 
78 	strncpy(rrng.type, "rng", sizeof(rrng.type));
79 
80 	rrng.seedsize = seedsize(alg);
81 
82 	if (nla_put(skb, CRYPTOCFGA_REPORT_RNG,
83 		    sizeof(struct crypto_report_rng), &rrng))
84 		goto nla_put_failure;
85 	return 0;
86 
87 nla_put_failure:
88 	return -EMSGSIZE;
89 }
90 #else
91 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
92 {
93 	return -ENOSYS;
94 }
95 #endif
96 
97 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
98 	__attribute__ ((unused));
99 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
100 {
101 	seq_printf(m, "type         : rng\n");
102 	seq_printf(m, "seedsize     : %u\n", seedsize(alg));
103 }
104 
105 static const struct crypto_type crypto_rng_type = {
106 	.extsize = crypto_alg_extsize,
107 	.init_tfm = crypto_rng_init_tfm,
108 #ifdef CONFIG_PROC_FS
109 	.show = crypto_rng_show,
110 #endif
111 	.report = crypto_rng_report,
112 	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
113 	.maskset = CRYPTO_ALG_TYPE_MASK,
114 	.type = CRYPTO_ALG_TYPE_RNG,
115 	.tfmsize = offsetof(struct crypto_rng, base),
116 };
117 
118 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
119 {
120 	return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
121 }
122 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
123 
124 int crypto_get_default_rng(void)
125 {
126 	struct crypto_rng *rng;
127 	int err;
128 
129 	mutex_lock(&crypto_default_rng_lock);
130 	if (!crypto_default_rng) {
131 		rng = crypto_alloc_rng("stdrng", 0, 0);
132 		err = PTR_ERR(rng);
133 		if (IS_ERR(rng))
134 			goto unlock;
135 
136 		err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
137 		if (err) {
138 			crypto_free_rng(rng);
139 			goto unlock;
140 		}
141 
142 		crypto_default_rng = rng;
143 	}
144 
145 	crypto_default_rng_refcnt++;
146 	err = 0;
147 
148 unlock:
149 	mutex_unlock(&crypto_default_rng_lock);
150 
151 	return err;
152 }
153 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
154 
155 void crypto_put_default_rng(void)
156 {
157 	mutex_lock(&crypto_default_rng_lock);
158 	crypto_default_rng_refcnt--;
159 	mutex_unlock(&crypto_default_rng_lock);
160 }
161 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
162 
163 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
164 int crypto_del_default_rng(void)
165 {
166 	int err = -EBUSY;
167 
168 	mutex_lock(&crypto_default_rng_lock);
169 	if (crypto_default_rng_refcnt)
170 		goto out;
171 
172 	crypto_free_rng(crypto_default_rng);
173 	crypto_default_rng = NULL;
174 
175 	err = 0;
176 
177 out:
178 	mutex_unlock(&crypto_default_rng_lock);
179 
180 	return err;
181 }
182 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
183 #endif
184 
185 int crypto_register_rng(struct rng_alg *alg)
186 {
187 	struct crypto_alg *base = &alg->base;
188 
189 	if (alg->seedsize > PAGE_SIZE / 8)
190 		return -EINVAL;
191 
192 	base->cra_type = &crypto_rng_type;
193 	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
194 	base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
195 
196 	return crypto_register_alg(base);
197 }
198 EXPORT_SYMBOL_GPL(crypto_register_rng);
199 
200 void crypto_unregister_rng(struct rng_alg *alg)
201 {
202 	crypto_unregister_alg(&alg->base);
203 }
204 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
205 
206 int crypto_register_rngs(struct rng_alg *algs, int count)
207 {
208 	int i, ret;
209 
210 	for (i = 0; i < count; i++) {
211 		ret = crypto_register_rng(algs + i);
212 		if (ret)
213 			goto err;
214 	}
215 
216 	return 0;
217 
218 err:
219 	for (--i; i >= 0; --i)
220 		crypto_unregister_rng(algs + i);
221 
222 	return ret;
223 }
224 EXPORT_SYMBOL_GPL(crypto_register_rngs);
225 
226 void crypto_unregister_rngs(struct rng_alg *algs, int count)
227 {
228 	int i;
229 
230 	for (i = count - 1; i >= 0; --i)
231 		crypto_unregister_rng(algs + i);
232 }
233 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
234 
235 MODULE_LICENSE("GPL");
236 MODULE_DESCRIPTION("Random Number Generator");
237