xref: /openbmc/linux/crypto/rng.c (revision cf21eb6a) 
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 
31 int 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);
53 free_buf:
54 	kfree_sensitive(buf);
55 out:
56 	return crypto_rng_errstat(alg, err);
57 }
58 EXPORT_SYMBOL_GPL(crypto_rng_reset);
59 
60 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
61 {
62 	return 0;
63 }
64 
65 static 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 
72 static 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 
86 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
87 	__maybe_unused;
88 static 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 
94 static 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 
115 static 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 
133 struct 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 }
137 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
138 
139 int 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 
163 unlock:
164 	mutex_unlock(&crypto_default_rng_lock);
165 
166 	return err;
167 }
168 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
169 
170 void 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 }
176 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
177 
178 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
179 int 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 
192 out:
193 	mutex_unlock(&crypto_default_rng_lock);
194 
195 	return err;
196 }
197 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
198 #endif
199 
200 int 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 }
217 EXPORT_SYMBOL_GPL(crypto_register_rng);
218 
219 void crypto_unregister_rng(struct rng_alg *alg)
220 {
221 	crypto_unregister_alg(&alg->base);
222 }
223 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
224 
225 int 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 
237 err:
238 	for (--i; i >= 0; --i)
239 		crypto_unregister_rng(algs + i);
240 
241 	return ret;
242 }
243 EXPORT_SYMBOL_GPL(crypto_register_rngs);
244 
245 void 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 }
252 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
253 
254 MODULE_LICENSE("GPL");
255 MODULE_DESCRIPTION("Random Number Generator");
256