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	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);
48out:
49	kfree_sensitive(buf);
50	return err;
51}
52EXPORT_SYMBOL_GPL(crypto_rng_reset);
53
54static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
55{
56	return 0;
57}
58
59static 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
66static 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
80static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
81	__maybe_unused;
82static 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
88static 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
103struct 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}
107EXPORT_SYMBOL_GPL(crypto_alloc_rng);
108
109int 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
133unlock:
134	mutex_unlock(&crypto_default_rng_lock);
135
136	return err;
137}
138EXPORT_SYMBOL_GPL(crypto_get_default_rng);
139
140void 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}
146EXPORT_SYMBOL_GPL(crypto_put_default_rng);
147
148#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
149int 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
162out:
163	mutex_unlock(&crypto_default_rng_lock);
164
165	return err;
166}
167EXPORT_SYMBOL_GPL(crypto_del_default_rng);
168#endif
169
170int 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}
183EXPORT_SYMBOL_GPL(crypto_register_rng);
184
185void crypto_unregister_rng(struct rng_alg *alg)
186{
187	crypto_unregister_alg(&alg->base);
188}
189EXPORT_SYMBOL_GPL(crypto_unregister_rng);
190
191int 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
203err:
204	for (--i; i >= 0; --i)
205		crypto_unregister_rng(algs + i);
206
207	return ret;
208}
209EXPORT_SYMBOL_GPL(crypto_register_rngs);
210
211void 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}
218EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
219
220MODULE_LICENSE("GPL");
221MODULE_DESCRIPTION("Random Number Generator");
222