xref: /kernel/linux/linux-5.10/crypto/rng.c (revision 8c2ecf20) 
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
26static DEFINE_MUTEX(crypto_default_rng_lock);
27struct crypto_rng *crypto_default_rng;
28EXPORT_SYMBOL_GPL(crypto_default_rng);
29static int crypto_default_rng_refcnt;
30
31int 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	if (!seed && slen) {
38		buf = kmalloc(slen, GFP_KERNEL);
39		if (!buf)
40			return -ENOMEM;
41
42		err = get_random_bytes_wait(buf, slen);
43		if (err)
44			goto out;
45		seed = buf;
46	}
47
48	crypto_stats_get(alg);
49	err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
50	crypto_stats_rng_seed(alg, err);
51out:
52	kfree_sensitive(buf);
53	return err;
54}
55EXPORT_SYMBOL_GPL(crypto_rng_reset);
56
57static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
58{
59	return 0;
60}
61
62static unsigned int seedsize(struct crypto_alg *alg)
63{
64	struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
65
66	return ralg->seedsize;
67}
68
69#ifdef CONFIG_NET
70static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
71{
72	struct crypto_report_rng rrng;
73
74	memset(&rrng, 0, sizeof(rrng));
75
76	strscpy(rrng.type, "rng", sizeof(rrng.type));
77
78	rrng.seedsize = seedsize(alg);
79
80	return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
81}
82#else
83static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
84{
85	return -ENOSYS;
86}
87#endif
88
89static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
90	__maybe_unused;
91static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
92{
93	seq_printf(m, "type         : rng\n");
94	seq_printf(m, "seedsize     : %u\n", seedsize(alg));
95}
96
97static const struct crypto_type crypto_rng_type = {
98	.extsize = crypto_alg_extsize,
99	.init_tfm = crypto_rng_init_tfm,
100#ifdef CONFIG_PROC_FS
101	.show = crypto_rng_show,
102#endif
103	.report = crypto_rng_report,
104	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
105	.maskset = CRYPTO_ALG_TYPE_MASK,
106	.type = CRYPTO_ALG_TYPE_RNG,
107	.tfmsize = offsetof(struct crypto_rng, base),
108};
109
110struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
111{
112	return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
113}
114EXPORT_SYMBOL_GPL(crypto_alloc_rng);
115
116int crypto_get_default_rng(void)
117{
118	struct crypto_rng *rng;
119	int err;
120
121	mutex_lock(&crypto_default_rng_lock);
122	if (!crypto_default_rng) {
123		rng = crypto_alloc_rng("stdrng", 0, 0);
124		err = PTR_ERR(rng);
125		if (IS_ERR(rng))
126			goto unlock;
127
128		err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
129		if (err) {
130			crypto_free_rng(rng);
131			goto unlock;
132		}
133
134		crypto_default_rng = rng;
135	}
136
137	crypto_default_rng_refcnt++;
138	err = 0;
139
140unlock:
141	mutex_unlock(&crypto_default_rng_lock);
142
143	return err;
144}
145EXPORT_SYMBOL_GPL(crypto_get_default_rng);
146
147void crypto_put_default_rng(void)
148{
149	mutex_lock(&crypto_default_rng_lock);
150	crypto_default_rng_refcnt--;
151	mutex_unlock(&crypto_default_rng_lock);
152}
153EXPORT_SYMBOL_GPL(crypto_put_default_rng);
154
155#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
156int crypto_del_default_rng(void)
157{
158	int err = -EBUSY;
159
160	mutex_lock(&crypto_default_rng_lock);
161	if (crypto_default_rng_refcnt)
162		goto out;
163
164	crypto_free_rng(crypto_default_rng);
165	crypto_default_rng = NULL;
166
167	err = 0;
168
169out:
170	mutex_unlock(&crypto_default_rng_lock);
171
172	return err;
173}
174EXPORT_SYMBOL_GPL(crypto_del_default_rng);
175#endif
176
177int crypto_register_rng(struct rng_alg *alg)
178{
179	struct crypto_alg *base = &alg->base;
180
181	if (alg->seedsize > PAGE_SIZE / 8)
182		return -EINVAL;
183
184	base->cra_type = &crypto_rng_type;
185	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
186	base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
187
188	return crypto_register_alg(base);
189}
190EXPORT_SYMBOL_GPL(crypto_register_rng);
191
192void crypto_unregister_rng(struct rng_alg *alg)
193{
194	crypto_unregister_alg(&alg->base);
195}
196EXPORT_SYMBOL_GPL(crypto_unregister_rng);
197
198int crypto_register_rngs(struct rng_alg *algs, int count)
199{
200	int i, ret;
201
202	for (i = 0; i < count; i++) {
203		ret = crypto_register_rng(algs + i);
204		if (ret)
205			goto err;
206	}
207
208	return 0;
209
210err:
211	for (--i; i >= 0; --i)
212		crypto_unregister_rng(algs + i);
213
214	return ret;
215}
216EXPORT_SYMBOL_GPL(crypto_register_rngs);
217
218void crypto_unregister_rngs(struct rng_alg *algs, int count)
219{
220	int i;
221
222	for (i = count - 1; i >= 0; --i)
223		crypto_unregister_rng(algs + i);
224}
225EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
226
227MODULE_LICENSE("GPL");
228MODULE_DESCRIPTION("Random Number Generator");
229