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
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 rng_alg *alg = crypto_rng_alg(tfm);
34	u8 *buf = NULL;
35	int err;
36
37	if (IS_ENABLED(CONFIG_CRYPTO_STATS))
38		atomic64_inc(&rng_get_stat(alg)->seed_cnt);
39
40	if (!seed && slen) {
41		buf = kmalloc(slen, GFP_KERNEL);
42		err = -ENOMEM;
43		if (!buf)
44			goto out;
45
46		err = get_random_bytes_wait(buf, slen);
47		if (err)
48			goto free_buf;
49		seed = buf;
50	}
51
52	err = alg->seed(tfm, seed, slen);
53free_buf:
54	kfree_sensitive(buf);
55out:
56	return crypto_rng_errstat(alg, err);
57}
58EXPORT_SYMBOL_GPL(crypto_rng_reset);
59
60static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
61{
62	return 0;
63}
64
65static unsigned int seedsize(struct crypto_alg *alg)
66{
67	struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
68
69	return ralg->seedsize;
70}
71
72static int __maybe_unused crypto_rng_report(
73	struct sk_buff *skb, struct crypto_alg *alg)
74{
75	struct crypto_report_rng rrng;
76
77	memset(&rrng, 0, sizeof(rrng));
78
79	strscpy(rrng.type, "rng", sizeof(rrng.type));
80
81	rrng.seedsize = seedsize(alg);
82
83	return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
84}
85
86static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
87	__maybe_unused;
88static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
89{
90	seq_printf(m, "type         : rng\n");
91	seq_printf(m, "seedsize     : %u\n", seedsize(alg));
92}
93
94static int __maybe_unused crypto_rng_report_stat(
95	struct sk_buff *skb, struct crypto_alg *alg)
96{
97	struct rng_alg *rng = __crypto_rng_alg(alg);
98	struct crypto_istat_rng *istat;
99	struct crypto_stat_rng rrng;
100
101	istat = rng_get_stat(rng);
102
103	memset(&rrng, 0, sizeof(rrng));
104
105	strscpy(rrng.type, "rng", sizeof(rrng.type));
106
107	rrng.stat_generate_cnt = atomic64_read(&istat->generate_cnt);
108	rrng.stat_generate_tlen = atomic64_read(&istat->generate_tlen);
109	rrng.stat_seed_cnt = atomic64_read(&istat->seed_cnt);
110	rrng.stat_err_cnt = atomic64_read(&istat->err_cnt);
111
112	return nla_put(skb, CRYPTOCFGA_STAT_RNG, sizeof(rrng), &rrng);
113}
114
115static const struct crypto_type crypto_rng_type = {
116	.extsize = crypto_alg_extsize,
117	.init_tfm = crypto_rng_init_tfm,
118#ifdef CONFIG_PROC_FS
119	.show = crypto_rng_show,
120#endif
121#if IS_ENABLED(CONFIG_CRYPTO_USER)
122	.report = crypto_rng_report,
123#endif
124#ifdef CONFIG_CRYPTO_STATS
125	.report_stat = crypto_rng_report_stat,
126#endif
127	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
128	.maskset = CRYPTO_ALG_TYPE_MASK,
129	.type = CRYPTO_ALG_TYPE_RNG,
130	.tfmsize = offsetof(struct crypto_rng, base),
131};
132
133struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
134{
135	return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
136}
137EXPORT_SYMBOL_GPL(crypto_alloc_rng);
138
139int crypto_get_default_rng(void)
140{
141	struct crypto_rng *rng;
142	int err;
143
144	mutex_lock(&crypto_default_rng_lock);
145	if (!crypto_default_rng) {
146		rng = crypto_alloc_rng("stdrng", 0, 0);
147		err = PTR_ERR(rng);
148		if (IS_ERR(rng))
149			goto unlock;
150
151		err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
152		if (err) {
153			crypto_free_rng(rng);
154			goto unlock;
155		}
156
157		crypto_default_rng = rng;
158	}
159
160	crypto_default_rng_refcnt++;
161	err = 0;
162
163unlock:
164	mutex_unlock(&crypto_default_rng_lock);
165
166	return err;
167}
168EXPORT_SYMBOL_GPL(crypto_get_default_rng);
169
170void crypto_put_default_rng(void)
171{
172	mutex_lock(&crypto_default_rng_lock);
173	crypto_default_rng_refcnt--;
174	mutex_unlock(&crypto_default_rng_lock);
175}
176EXPORT_SYMBOL_GPL(crypto_put_default_rng);
177
178#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
179int crypto_del_default_rng(void)
180{
181	int err = -EBUSY;
182
183	mutex_lock(&crypto_default_rng_lock);
184	if (crypto_default_rng_refcnt)
185		goto out;
186
187	crypto_free_rng(crypto_default_rng);
188	crypto_default_rng = NULL;
189
190	err = 0;
191
192out:
193	mutex_unlock(&crypto_default_rng_lock);
194
195	return err;
196}
197EXPORT_SYMBOL_GPL(crypto_del_default_rng);
198#endif
199
200int crypto_register_rng(struct rng_alg *alg)
201{
202	struct crypto_istat_rng *istat = rng_get_stat(alg);
203	struct crypto_alg *base = &alg->base;
204
205	if (alg->seedsize > PAGE_SIZE / 8)
206		return -EINVAL;
207
208	base->cra_type = &crypto_rng_type;
209	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
210	base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
211
212	if (IS_ENABLED(CONFIG_CRYPTO_STATS))
213		memset(istat, 0, sizeof(*istat));
214
215	return crypto_register_alg(base);
216}
217EXPORT_SYMBOL_GPL(crypto_register_rng);
218
219void crypto_unregister_rng(struct rng_alg *alg)
220{
221	crypto_unregister_alg(&alg->base);
222}
223EXPORT_SYMBOL_GPL(crypto_unregister_rng);
224
225int crypto_register_rngs(struct rng_alg *algs, int count)
226{
227	int i, ret;
228
229	for (i = 0; i < count; i++) {
230		ret = crypto_register_rng(algs + i);
231		if (ret)
232			goto err;
233	}
234
235	return 0;
236
237err:
238	for (--i; i >= 0; --i)
239		crypto_unregister_rng(algs + i);
240
241	return ret;
242}
243EXPORT_SYMBOL_GPL(crypto_register_rngs);
244
245void crypto_unregister_rngs(struct rng_alg *algs, int count)
246{
247	int i;
248
249	for (i = count - 1; i >= 0; --i)
250		crypto_unregister_rng(algs + i);
251}
252EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
253
254MODULE_LICENSE("GPL");
255MODULE_DESCRIPTION("Random Number Generator");
256