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