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Linux/crypto/rng.c

  1 /*
  2  * Cryptographic API.
  3  *
  4  * RNG operations.
  5  *
  6  * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
  7  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
  8  *
  9  * This program is free software; you can redistribute it and/or modify it
 10  * under the terms of the GNU General Public License as published by the Free
 11  * Software Foundation; either version 2 of the License, or (at your option)
 12  * any later version.
 13  *
 14  */
 15 
 16 #include <linux/atomic.h>
 17 #include <crypto/internal/rng.h>
 18 #include <linux/err.h>
 19 #include <linux/module.h>
 20 #include <linux/mutex.h>
 21 #include <linux/random.h>
 22 #include <linux/seq_file.h>
 23 #include <linux/slab.h>
 24 #include <linux/string.h>
 25 #include <linux/cryptouser.h>
 26 #include <net/netlink.h>
 27 
 28 #include "internal.h"
 29 
 30 static DEFINE_MUTEX(crypto_default_rng_lock);
 31 struct crypto_rng *crypto_default_rng;
 32 EXPORT_SYMBOL_GPL(crypto_default_rng);
 33 static int crypto_default_rng_refcnt;
 34 
 35 static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm)
 36 {
 37         return container_of(tfm, struct crypto_rng, base);
 38 }
 39 
 40 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
 41 {
 42         u8 *buf = NULL;
 43         int err;
 44 
 45         if (!seed && slen) {
 46                 buf = kmalloc(slen, GFP_KERNEL);
 47                 if (!buf)
 48                         return -ENOMEM;
 49 
 50                 get_random_bytes(buf, slen);
 51                 seed = buf;
 52         }
 53 
 54         err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
 55 
 56         kzfree(buf);
 57         return err;
 58 }
 59 EXPORT_SYMBOL_GPL(crypto_rng_reset);
 60 
 61 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
 62 {
 63         return 0;
 64 }
 65 
 66 static unsigned int seedsize(struct crypto_alg *alg)
 67 {
 68         struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
 69 
 70         return ralg->seedsize;
 71 }
 72 
 73 #ifdef CONFIG_NET
 74 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
 75 {
 76         struct crypto_report_rng rrng;
 77 
 78         strncpy(rrng.type, "rng", sizeof(rrng.type));
 79 
 80         rrng.seedsize = seedsize(alg);
 81 
 82         if (nla_put(skb, CRYPTOCFGA_REPORT_RNG,
 83                     sizeof(struct crypto_report_rng), &rrng))
 84                 goto nla_put_failure;
 85         return 0;
 86 
 87 nla_put_failure:
 88         return -EMSGSIZE;
 89 }
 90 #else
 91 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
 92 {
 93         return -ENOSYS;
 94 }
 95 #endif
 96 
 97 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
 98         __attribute__ ((unused));
 99 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
100 {
101         seq_printf(m, "type         : rng\n");
102         seq_printf(m, "seedsize     : %u\n", seedsize(alg));
103 }
104 
105 static const struct crypto_type crypto_rng_type = {
106         .extsize = crypto_alg_extsize,
107         .init_tfm = crypto_rng_init_tfm,
108 #ifdef CONFIG_PROC_FS
109         .show = crypto_rng_show,
110 #endif
111         .report = crypto_rng_report,
112         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
113         .maskset = CRYPTO_ALG_TYPE_MASK,
114         .type = CRYPTO_ALG_TYPE_RNG,
115         .tfmsize = offsetof(struct crypto_rng, base),
116 };
117 
118 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
119 {
120         return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
121 }
122 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
123 
124 int crypto_get_default_rng(void)
125 {
126         struct crypto_rng *rng;
127         int err;
128 
129         mutex_lock(&crypto_default_rng_lock);
130         if (!crypto_default_rng) {
131                 rng = crypto_alloc_rng("stdrng", 0, 0);
132                 err = PTR_ERR(rng);
133                 if (IS_ERR(rng))
134                         goto unlock;
135 
136                 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
137                 if (err) {
138                         crypto_free_rng(rng);
139                         goto unlock;
140                 }
141 
142                 crypto_default_rng = rng;
143         }
144 
145         crypto_default_rng_refcnt++;
146         err = 0;
147 
148 unlock:
149         mutex_unlock(&crypto_default_rng_lock);
150 
151         return err;
152 }
153 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
154 
155 void crypto_put_default_rng(void)
156 {
157         mutex_lock(&crypto_default_rng_lock);
158         crypto_default_rng_refcnt--;
159         mutex_unlock(&crypto_default_rng_lock);
160 }
161 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
162 
163 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
164 int crypto_del_default_rng(void)
165 {
166         int err = -EBUSY;
167 
168         mutex_lock(&crypto_default_rng_lock);
169         if (crypto_default_rng_refcnt)
170                 goto out;
171 
172         crypto_free_rng(crypto_default_rng);
173         crypto_default_rng = NULL;
174 
175         err = 0;
176 
177 out:
178         mutex_unlock(&crypto_default_rng_lock);
179 
180         return err;
181 }
182 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
183 #endif
184 
185 int crypto_register_rng(struct rng_alg *alg)
186 {
187         struct crypto_alg *base = &alg->base;
188 
189         if (alg->seedsize > PAGE_SIZE / 8)
190                 return -EINVAL;
191 
192         base->cra_type = &crypto_rng_type;
193         base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
194         base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
195 
196         return crypto_register_alg(base);
197 }
198 EXPORT_SYMBOL_GPL(crypto_register_rng);
199 
200 void crypto_unregister_rng(struct rng_alg *alg)
201 {
202         crypto_unregister_alg(&alg->base);
203 }
204 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
205 
206 int crypto_register_rngs(struct rng_alg *algs, int count)
207 {
208         int i, ret;
209 
210         for (i = 0; i < count; i++) {
211                 ret = crypto_register_rng(algs + i);
212                 if (ret)
213                         goto err;
214         }
215 
216         return 0;
217 
218 err:
219         for (--i; i >= 0; --i)
220                 crypto_unregister_rng(algs + i);
221 
222         return ret;
223 }
224 EXPORT_SYMBOL_GPL(crypto_register_rngs);
225 
226 void crypto_unregister_rngs(struct rng_alg *algs, int count)
227 {
228         int i;
229 
230         for (i = count - 1; i >= 0; --i)
231                 crypto_unregister_rng(algs + i);
232 }
233 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
234 
235 MODULE_LICENSE("GPL");
236 MODULE_DESCRIPTION("Random Number Generator");
237 

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