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");