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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Cryptographic API.
4 *
5 * RNG operations.
6 *
7 * Copyright (c) 2008 Neil Horman <[email protected]>
8 * Copyright (c) 2015 Herbert Xu <[email protected]>
9 */
10
11#include <crypto/internal/rng.h>
12#include <linux/atomic.h>
13#include <linux/cryptouser.h>
14#include <linux/err.h>
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/mutex.h>
18#include <linux/random.h>
19#include <linux/seq_file.h>
20#include <linux/slab.h>
21#include <linux/string.h>
22#include <net/netlink.h>
23
24#include "internal.h"
25
26static DEFINE_MUTEX(crypto_default_rng_lock);
27static struct crypto_rng *crypto_default_rng;
28static int crypto_default_rng_refcnt;
29
30int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
31{
32 u8 *buf = NULL;
33 int err;
34
35 if (!seed && slen) {
36 buf = kmalloc(slen, GFP_KERNEL);
37 if (!buf)
38 return -ENOMEM;
39
40 err = get_random_bytes_wait(buf, slen);
41 if (err)
42 goto out;
43 seed = buf;
44 }
45
46 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
47out:
48 kfree_sensitive(buf);
49 return err;
50}
51EXPORT_SYMBOL_GPL(crypto_rng_reset);
52
53static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
54{
55 return 0;
56}
57
58static unsigned int seedsize(struct crypto_alg *alg)
59{
60 struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
61
62 return ralg->seedsize;
63}
64
65static int __maybe_unused crypto_rng_report(
66 struct sk_buff *skb, struct crypto_alg *alg)
67{
68 struct crypto_report_rng rrng = {
69 .type = "rng",
70 };
71
72 rrng.seedsize = seedsize(alg);
73
74 return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
75}
76
77static void __maybe_unused crypto_rng_show(struct seq_file *m,
78 struct crypto_alg *alg)
79{
80 seq_printf(m, "type : rng\n");
81 seq_printf(m, "seedsize : %u\n", seedsize(alg));
82}
83
84static const struct crypto_type crypto_rng_type = {
85 .extsize = crypto_alg_extsize,
86 .init_tfm = crypto_rng_init_tfm,
87#ifdef CONFIG_PROC_FS
88 .show = crypto_rng_show,
89#endif
90#if IS_ENABLED(CONFIG_CRYPTO_USER)
91 .report = crypto_rng_report,
92#endif
93 .maskclear = ~CRYPTO_ALG_TYPE_MASK,
94 .maskset = CRYPTO_ALG_TYPE_MASK,
95 .type = CRYPTO_ALG_TYPE_RNG,
96 .tfmsize = offsetof(struct crypto_rng, base),
97 .algsize = offsetof(struct rng_alg, base),
98};
99
100struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
101{
102 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
103}
104EXPORT_SYMBOL_GPL(crypto_alloc_rng);
105
106static int crypto_get_default_rng(void)
107{
108 struct crypto_rng *rng;
109 int err;
110
111 mutex_lock(&crypto_default_rng_lock);
112 if (!crypto_default_rng) {
113 rng = crypto_alloc_rng("stdrng", 0, 0);
114 err = PTR_ERR(rng);
115 if (IS_ERR(rng))
116 goto unlock;
117
118 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
119 if (err) {
120 crypto_free_rng(rng);
121 goto unlock;
122 }
123
124 crypto_default_rng = rng;
125 }
126
127 crypto_default_rng_refcnt++;
128 err = 0;
129
130unlock:
131 mutex_unlock(&crypto_default_rng_lock);
132
133 return err;
134}
135
136static void crypto_put_default_rng(void)
137{
138 mutex_lock(&crypto_default_rng_lock);
139 crypto_default_rng_refcnt--;
140 mutex_unlock(&crypto_default_rng_lock);
141}
142
143int __crypto_stdrng_get_bytes(void *buf, unsigned int len)
144{
145 int err;
146
147 err = crypto_get_default_rng();
148 if (err)
149 return err;
150
151 err = crypto_rng_get_bytes(crypto_default_rng, buf, len);
152 crypto_put_default_rng();
153 return err;
154}
155EXPORT_SYMBOL_GPL(__crypto_stdrng_get_bytes);
156
157#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
158int crypto_del_default_rng(void)
159{
160 int err = -EBUSY;
161
162 mutex_lock(&crypto_default_rng_lock);
163 if (crypto_default_rng_refcnt)
164 goto out;
165
166 crypto_free_rng(crypto_default_rng);
167 crypto_default_rng = NULL;
168
169 err = 0;
170
171out:
172 mutex_unlock(&crypto_default_rng_lock);
173
174 return err;
175}
176EXPORT_SYMBOL_GPL(crypto_del_default_rng);
177#endif
178
179static void rng_default_set_ent(struct crypto_rng *tfm, const u8 *data,
180 unsigned int len)
181{
182}
183
184int crypto_register_rng(struct rng_alg *alg)
185{
186 struct crypto_alg *base = &alg->base;
187
188 if (alg->seedsize > PAGE_SIZE / 8)
189 return -EINVAL;
190
191 base->cra_type = &crypto_rng_type;
192 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
193 base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
194
195 if (!alg->set_ent)
196 alg->set_ent = rng_default_set_ent;
197
198 return crypto_register_alg(base);
199}
200EXPORT_SYMBOL_GPL(crypto_register_rng);
201
202void crypto_unregister_rng(struct rng_alg *alg)
203{
204 crypto_unregister_alg(&alg->base);
205}
206EXPORT_SYMBOL_GPL(crypto_unregister_rng);
207
208int crypto_register_rngs(struct rng_alg *algs, int count)
209{
210 int i, ret;
211
212 for (i = 0; i < count; i++) {
213 ret = crypto_register_rng(algs + i);
214 if (ret) {
215 crypto_unregister_rngs(algs, i);
216 return ret;
217 }
218 }
219
220 return 0;
221}
222EXPORT_SYMBOL_GPL(crypto_register_rngs);
223
224void crypto_unregister_rngs(struct rng_alg *algs, int count)
225{
226 int i;
227
228 for (i = count - 1; i >= 0; --i)
229 crypto_unregister_rng(algs + i);
230}
231EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
232
233static void __exit rng_exit(void)
234{
235 int err;
236
237 err = crypto_del_default_rng();
238 if (err)
239 pr_err("Failed delete default RNG: %d\n", err);
240}
241
242module_exit(rng_exit);
243
244MODULE_LICENSE("GPL");
245MODULE_DESCRIPTION("Random Number Generator");