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
crypto_rng_reset(struct crypto_rng * tfm,const u8 * seed,unsigned int slen)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
crypto_rng_init_tfm(struct crypto_tfm * tfm)60 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
61 {
62 return 0;
63 }
64
seedsize(struct crypto_alg * alg)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
crypto_rng_report(struct sk_buff * skb,struct crypto_alg * alg)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;
crypto_rng_show(struct seq_file * m,struct crypto_alg * alg)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
crypto_rng_report_stat(struct sk_buff * skb,struct crypto_alg * alg)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
crypto_alloc_rng(const char * alg_name,u32 type,u32 mask)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
crypto_get_default_rng(void)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
crypto_put_default_rng(void)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)
crypto_del_default_rng(void)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
crypto_register_rng(struct rng_alg * alg)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
crypto_unregister_rng(struct rng_alg * alg)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
crypto_register_rngs(struct rng_alg * algs,int count)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
crypto_unregister_rngs(struct rng_alg * algs,int count)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