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 <linux/compiler.h>
  27 #include <net/netlink.h>
  28
  29 #include "internal.h"
  30
  31 static DEFINE_MUTEX(crypto_default_rng_lock);
  32 struct crypto_rng *crypto_default_rng;
  33 EXPORT_SYMBOL_GPL(crypto_default_rng);
  34 static int crypto_default_rng_refcnt;
  35
  36 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
  37 {
  38         u8 *buf = NULL;
  39         int err;
  40
  41         if (!seed && slen) {
  42                 buf = kmalloc(slen, GFP_KERNEL);
  43                 if (!buf)
  44                         return -ENOMEM;
  45
  46                 err = get_random_bytes_wait(buf, slen);
  47                 if (err)
  48                         goto out;
  49                 seed = buf;
  50         }
  51
  52         err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
  53         crypto_stat_rng_seed(tfm, err);
  54 out:
  55         kzfree(buf);
  56         return 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 #ifdef CONFIG_NET
  73 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  74 {
  75         struct crypto_report_rng rrng;
  76
  77         strncpy(rrng.type, "rng", sizeof(rrng.type));
  78
  79         rrng.seedsize = seedsize(alg);
  80
  81         if (nla_put(skb, CRYPTOCFGA_REPORT_RNG,
  82                     sizeof(struct crypto_report_rng), &rrng))
  83                 goto nla_put_failure;
  84         return 0;
  85
  86 nla_put_failure:
  87         return -EMSGSIZE;
  88 }
  89 #else
  90 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  91 {
  92         return -ENOSYS;
  93 }
  94 #endif
  95
  96 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  97         __maybe_unused;
  98 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  99 {
 100         seq_printf(m, "type         : rng\n");
 101         seq_printf(m, "seedsize     : %u\n", seedsize(alg));
 102 }
 103
 104 static const struct crypto_type crypto_rng_type = {
 105         .extsize = crypto_alg_extsize,
 106         .init_tfm = crypto_rng_init_tfm,
 107 #ifdef CONFIG_PROC_FS
 108         .show = crypto_rng_show,
 109 #endif
 110         .report = crypto_rng_report,
 111         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
 112         .maskset = CRYPTO_ALG_TYPE_MASK,
 113         .type = CRYPTO_ALG_TYPE_RNG,
 114         .tfmsize = offsetof(struct crypto_rng, base),
 115 };
 116
 117 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
 118 {
 119         return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
 120 }
 121 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
 122
 123 int crypto_get_default_rng(void)
 124 {
 125         struct crypto_rng *rng;
 126         int err;
 127
 128         mutex_lock(&crypto_default_rng_lock);
 129         if (!crypto_default_rng) {
 130                 rng = crypto_alloc_rng("stdrng", 0, 0);
 131                 err = PTR_ERR(rng);
 132                 if (IS_ERR(rng))
 133                         goto unlock;
 134
 135                 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
 136                 if (err) {
 137                         crypto_free_rng(rng);
 138                         goto unlock;
 139                 }
 140
 141                 crypto_default_rng = rng;
 142         }
 143
 144         crypto_default_rng_refcnt++;
 145         err = 0;
 146
 147 unlock:
 148         mutex_unlock(&crypto_default_rng_lock);
 149
 150         return err;
 151 }
 152 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 153
 154 void crypto_put_default_rng(void)
 155 {
 156         mutex_lock(&crypto_default_rng_lock);
 157         crypto_default_rng_refcnt--;
 158         mutex_unlock(&crypto_default_rng_lock);
 159 }
 160 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 161
 162 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
 163 int crypto_del_default_rng(void)
 164 {
 165         int err = -EBUSY;
 166
 167         mutex_lock(&crypto_default_rng_lock);
 168         if (crypto_default_rng_refcnt)
 169                 goto out;
 170
 171         crypto_free_rng(crypto_default_rng);
 172         crypto_default_rng = NULL;
 173
 174         err = 0;
 175
 176 out:
 177         mutex_unlock(&crypto_default_rng_lock);
 178
 179         return err;
 180 }
 181 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
 182 #endif
 183
 184 int crypto_register_rng(struct rng_alg *alg)
 185 {
 186         struct crypto_alg *base = &alg->base;
 187
 188         if (alg->seedsize > PAGE_SIZE / 8)
 189                 return -EINVAL;
 190
 191         base->cra_type = &crypto_rng_type;
 192         base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
 193         base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
 194
 195         return crypto_register_alg(base);
 196 }
 197 EXPORT_SYMBOL_GPL(crypto_register_rng);
 198
 199 void crypto_unregister_rng(struct rng_alg *alg)
 200 {
 201         crypto_unregister_alg(&alg->base);
 202 }
 203 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
 204
 205 int crypto_register_rngs(struct rng_alg *algs, int count)
 206 {
 207         int i, ret;
 208
 209         for (i = 0; i < count; i++) {
 210                 ret = crypto_register_rng(algs + i);
 211                 if (ret)
 212                         goto err;
 213         }
 214
 215         return 0;
 216
 217 err:
 218         for (--i; i >= 0; --i)
 219                 crypto_unregister_rng(algs + i);
 220
 221         return ret;
 222 }
 223 EXPORT_SYMBOL_GPL(crypto_register_rngs);
 224
 225 void crypto_unregister_rngs(struct rng_alg *algs, int count)
 226 {
 227         int i;
 228
 229         for (i = count - 1; i >= 0; --i)
 230                 crypto_unregister_rng(algs + i);
 231 }
 232 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
 233
 234 MODULE_LICENSE("GPL");
 235 MODULE_DESCRIPTION("Random Number Generator");