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