rng.c

  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	.algsize = offsetof(struct rng_alg, base),
102};
103
104struct 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}
108EXPORT_SYMBOL_GPL(crypto_alloc_rng);
109
110int 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
134unlock:
135	mutex_unlock(&crypto_default_rng_lock);
136
137	return err;
138}
139EXPORT_SYMBOL_GPL(crypto_get_default_rng);
140
141void 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}
147EXPORT_SYMBOL_GPL(crypto_put_default_rng);
148
149#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
150int 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
163out:
164	mutex_unlock(&crypto_default_rng_lock);
165
166	return err;
167}
168EXPORT_SYMBOL_GPL(crypto_del_default_rng);
169#endif
170
171static void rng_default_set_ent(struct crypto_rng *tfm, const u8 *data,
172				unsigned int len)
173{
174}
175
176int crypto_register_rng(struct rng_alg *alg)
177{
178	struct crypto_alg *base = &alg->base;
179
180	if (alg->seedsize > PAGE_SIZE / 8)
181		return -EINVAL;
182
183	base->cra_type = &crypto_rng_type;
184	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
185	base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
186
187	if (!alg->set_ent)
188		alg->set_ent = rng_default_set_ent;
189
190	return crypto_register_alg(base);
191}
192EXPORT_SYMBOL_GPL(crypto_register_rng);
193
194void crypto_unregister_rng(struct rng_alg *alg)
195{
196	crypto_unregister_alg(&alg->base);
197}
198EXPORT_SYMBOL_GPL(crypto_unregister_rng);
199
200int crypto_register_rngs(struct rng_alg *algs, int count)
201{
202	int i, ret;
203
204	for (i = 0; i < count; i++) {
205		ret = crypto_register_rng(algs + i);
206		if (ret)
207			goto err;
208	}
209
210	return 0;
211
212err:
213	for (--i; i >= 0; --i)
214		crypto_unregister_rng(algs + i);
215
216	return ret;
217}
218EXPORT_SYMBOL_GPL(crypto_register_rngs);
219
220void crypto_unregister_rngs(struct rng_alg *algs, int count)
221{
222	int i;
223
224	for (i = count - 1; i >= 0; --i)
225		crypto_unregister_rng(algs + i);
226}
227EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
228
229MODULE_LICENSE("GPL");
230MODULE_DESCRIPTION("Random Number Generator");