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 <linux/compiler.h>
27#include <net/netlink.h>
28
29#include "internal.h"
30
31static DEFINE_MUTEX(crypto_default_rng_lock);
32struct crypto_rng *crypto_default_rng;
33EXPORT_SYMBOL_GPL(crypto_default_rng);
34static int crypto_default_rng_refcnt;
35
36int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
37{
38 struct crypto_alg *alg = tfm->base.__crt_alg;
39 u8 *buf = NULL;
40 int err;
41
42 crypto_stats_get(alg);
43 if (!seed && slen) {
44 buf = kmalloc(slen, GFP_KERNEL);
45 if (!buf)
46 return -ENOMEM;
47
48 err = get_random_bytes_wait(buf, slen);
49 if (err)
50 goto out;
51 seed = buf;
52 }
53
54 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
55 crypto_stats_rng_seed(alg, err);
56out:
57 kzfree(buf);
58 return err;
59}
60EXPORT_SYMBOL_GPL(crypto_rng_reset);
61
62static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
63{
64 return 0;
65}
66
67static unsigned int seedsize(struct crypto_alg *alg)
68{
69 struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
70
71 return ralg->seedsize;
72}
73
74#ifdef CONFIG_NET
75static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
76{
77 struct crypto_report_rng rrng;
78
79 memset(&rrng, 0, sizeof(rrng));
80
81 strscpy(rrng.type, "rng", sizeof(rrng.type));
82
83 rrng.seedsize = seedsize(alg);
84
85 return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
86}
87#else
88static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
89{
90 return -ENOSYS;
91}
92#endif
93
94static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
95 __maybe_unused;
96static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
97{
98 seq_printf(m, "type : rng\n");
99 seq_printf(m, "seedsize : %u\n", seedsize(alg));
100}
101
102static const struct crypto_type crypto_rng_type = {
103 .extsize = crypto_alg_extsize,
104 .init_tfm = crypto_rng_init_tfm,
105#ifdef CONFIG_PROC_FS
106 .show = crypto_rng_show,
107#endif
108 .report = crypto_rng_report,
109 .maskclear = ~CRYPTO_ALG_TYPE_MASK,
110 .maskset = CRYPTO_ALG_TYPE_MASK,
111 .type = CRYPTO_ALG_TYPE_RNG,
112 .tfmsize = offsetof(struct crypto_rng, base),
113};
114
115struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
116{
117 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
118}
119EXPORT_SYMBOL_GPL(crypto_alloc_rng);
120
121int crypto_get_default_rng(void)
122{
123 struct crypto_rng *rng;
124 int err;
125
126 mutex_lock(&crypto_default_rng_lock);
127 if (!crypto_default_rng) {
128 rng = crypto_alloc_rng("stdrng", 0, 0);
129 err = PTR_ERR(rng);
130 if (IS_ERR(rng))
131 goto unlock;
132
133 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
134 if (err) {
135 crypto_free_rng(rng);
136 goto unlock;
137 }
138
139 crypto_default_rng = rng;
140 }
141
142 crypto_default_rng_refcnt++;
143 err = 0;
144
145unlock:
146 mutex_unlock(&crypto_default_rng_lock);
147
148 return err;
149}
150EXPORT_SYMBOL_GPL(crypto_get_default_rng);
151
152void crypto_put_default_rng(void)
153{
154 mutex_lock(&crypto_default_rng_lock);
155 crypto_default_rng_refcnt--;
156 mutex_unlock(&crypto_default_rng_lock);
157}
158EXPORT_SYMBOL_GPL(crypto_put_default_rng);
159
160#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
161int crypto_del_default_rng(void)
162{
163 int err = -EBUSY;
164
165 mutex_lock(&crypto_default_rng_lock);
166 if (crypto_default_rng_refcnt)
167 goto out;
168
169 crypto_free_rng(crypto_default_rng);
170 crypto_default_rng = NULL;
171
172 err = 0;
173
174out:
175 mutex_unlock(&crypto_default_rng_lock);
176
177 return err;
178}
179EXPORT_SYMBOL_GPL(crypto_del_default_rng);
180#endif
181
182int crypto_register_rng(struct rng_alg *alg)
183{
184 struct crypto_alg *base = &alg->base;
185
186 if (alg->seedsize > PAGE_SIZE / 8)
187 return -EINVAL;
188
189 base->cra_type = &crypto_rng_type;
190 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
191 base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
192
193 return crypto_register_alg(base);
194}
195EXPORT_SYMBOL_GPL(crypto_register_rng);
196
197void crypto_unregister_rng(struct rng_alg *alg)
198{
199 crypto_unregister_alg(&alg->base);
200}
201EXPORT_SYMBOL_GPL(crypto_unregister_rng);
202
203int crypto_register_rngs(struct rng_alg *algs, int count)
204{
205 int i, ret;
206
207 for (i = 0; i < count; i++) {
208 ret = crypto_register_rng(algs + i);
209 if (ret)
210 goto err;
211 }
212
213 return 0;
214
215err:
216 for (--i; i >= 0; --i)
217 crypto_unregister_rng(algs + i);
218
219 return ret;
220}
221EXPORT_SYMBOL_GPL(crypto_register_rngs);
222
223void crypto_unregister_rngs(struct rng_alg *algs, int count)
224{
225 int i;
226
227 for (i = count - 1; i >= 0; --i)
228 crypto_unregister_rng(algs + i);
229}
230EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
231
232MODULE_LICENSE("GPL");
233MODULE_DESCRIPTION("Random Number Generator");
234