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
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 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
crypto_rng_init_tfm(struct crypto_tfm * tfm)54 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
55 {
56 return 0;
57 }
58
seedsize(struct crypto_alg * alg)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
crypto_rng_report(struct sk_buff * skb,struct crypto_alg * alg)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;
crypto_rng_show(struct seq_file * m,struct crypto_alg * alg)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 .algsize = offsetof(struct rng_alg, base),
102 };
103
crypto_alloc_rng(const char * alg_name,u32 type,u32 mask)104 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
105 {
106 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
107 }
108 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
109
crypto_get_default_rng(void)110 int crypto_get_default_rng(void)
111 {
112 struct crypto_rng *rng;
113 int err;
114
115 mutex_lock(&crypto_default_rng_lock);
116 if (!crypto_default_rng) {
117 rng = crypto_alloc_rng("stdrng", 0, 0);
118 err = PTR_ERR(rng);
119 if (IS_ERR(rng))
120 goto unlock;
121
122 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
123 if (err) {
124 crypto_free_rng(rng);
125 goto unlock;
126 }
127
128 crypto_default_rng = rng;
129 }
130
131 crypto_default_rng_refcnt++;
132 err = 0;
133
134 unlock:
135 mutex_unlock(&crypto_default_rng_lock);
136
137 return err;
138 }
139 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
140
crypto_put_default_rng(void)141 void crypto_put_default_rng(void)
142 {
143 mutex_lock(&crypto_default_rng_lock);
144 crypto_default_rng_refcnt--;
145 mutex_unlock(&crypto_default_rng_lock);
146 }
147 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
148
149 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
crypto_del_default_rng(void)150 int crypto_del_default_rng(void)
151 {
152 int err = -EBUSY;
153
154 mutex_lock(&crypto_default_rng_lock);
155 if (crypto_default_rng_refcnt)
156 goto out;
157
158 crypto_free_rng(crypto_default_rng);
159 crypto_default_rng = NULL;
160
161 err = 0;
162
163 out:
164 mutex_unlock(&crypto_default_rng_lock);
165
166 return err;
167 }
168 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
169 #endif
170
crypto_register_rng(struct rng_alg * alg)171 int crypto_register_rng(struct rng_alg *alg)
172 {
173 struct crypto_alg *base = &alg->base;
174
175 if (alg->seedsize > PAGE_SIZE / 8)
176 return -EINVAL;
177
178 base->cra_type = &crypto_rng_type;
179 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
180 base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
181
182 return crypto_register_alg(base);
183 }
184 EXPORT_SYMBOL_GPL(crypto_register_rng);
185
crypto_unregister_rng(struct rng_alg * alg)186 void crypto_unregister_rng(struct rng_alg *alg)
187 {
188 crypto_unregister_alg(&alg->base);
189 }
190 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
191
crypto_register_rngs(struct rng_alg * algs,int count)192 int crypto_register_rngs(struct rng_alg *algs, int count)
193 {
194 int i, ret;
195
196 for (i = 0; i < count; i++) {
197 ret = crypto_register_rng(algs + i);
198 if (ret)
199 goto err;
200 }
201
202 return 0;
203
204 err:
205 for (--i; i >= 0; --i)
206 crypto_unregister_rng(algs + i);
207
208 return ret;
209 }
210 EXPORT_SYMBOL_GPL(crypto_register_rngs);
211
crypto_unregister_rngs(struct rng_alg * algs,int count)212 void crypto_unregister_rngs(struct rng_alg *algs, int count)
213 {
214 int i;
215
216 for (i = count - 1; i >= 0; --i)
217 crypto_unregister_rng(algs + i);
218 }
219 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
220
221 MODULE_LICENSE("GPL");
222 MODULE_DESCRIPTION("Random Number Generator");
223