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 out:
  54         kzfree(buf);
  55         return err;
  56 }
  57 EXPORT_SYMBOL_GPL(crypto_rng_reset);
  58
  59 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
  60 {
  61         return 0;
  62 }
  63
  64 static unsigned int seedsize(struct crypto_alg *alg)
  65 {
  66         struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
  67
  68         return ralg->seedsize;
  69 }
  70
  71 #ifdef CONFIG_NET
  72 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  73 {
  74         struct crypto_report_rng rrng;
  75
  76         strncpy(rrng.type, "rng", sizeof(rrng.type));
  77
  78         rrng.seedsize = seedsize(alg);
  79
  80         if (nla_put(skb, CRYPTOCFGA_REPORT_RNG,
  81                     sizeof(struct crypto_report_rng), &rrng))
  82                 goto nla_put_failure;
  83         return 0;
  84
  85 nla_put_failure:
  86         return -EMSGSIZE;
  87 }
  88 #else
  89 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  90 {
  91         return -ENOSYS;
  92 }
  93 #endif
  94
  95 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  96         __maybe_unused;
  97 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  98 {
  99         seq_printf(m, "type         : rng\n");
 100         seq_printf(m, "seedsize     : %u\n", seedsize(alg));
 101 }
 102
 103 static const struct crypto_type crypto_rng_type = {
 104         .extsize = crypto_alg_extsize,
 105         .init_tfm = crypto_rng_init_tfm,
 106 #ifdef CONFIG_PROC_FS
 107         .show = crypto_rng_show,
 108 #endif
 109         .report = crypto_rng_report,
 110         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
 111         .maskset = CRYPTO_ALG_TYPE_MASK,
 112         .type = CRYPTO_ALG_TYPE_RNG,
 113         .tfmsize = offsetof(struct crypto_rng, base),
 114 };
 115
 116 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
 117 {
 118         return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
 119 }
 120 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
 121
 122 int crypto_get_default_rng(void)
 123 {
 124         struct crypto_rng *rng;
 125         int err;
 126
 127         mutex_lock(&crypto_default_rng_lock);
 128         if (!crypto_default_rng) {
 129                 rng = crypto_alloc_rng("stdrng", 0, 0);
 130                 err = PTR_ERR(rng);
 131                 if (IS_ERR(rng))
 132                         goto unlock;
 133
 134                 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
 135                 if (err) {
 136                         crypto_free_rng(rng);
 137                         goto unlock;
 138                 }
 139
 140                 crypto_default_rng = rng;
 141         }
 142
 143         crypto_default_rng_refcnt++;
 144         err = 0;
 145
 146 unlock:
 147         mutex_unlock(&crypto_default_rng_lock);
 148
 149         return err;
 150 }
 151 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 152
 153 void crypto_put_default_rng(void)
 154 {
 155         mutex_lock(&crypto_default_rng_lock);
 156         crypto_default_rng_refcnt--;
 157         mutex_unlock(&crypto_default_rng_lock);
 158 }
 159 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 160
 161 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
 162 int crypto_del_default_rng(void)
 163 {
 164         int err = -EBUSY;
 165
 166         mutex_lock(&crypto_default_rng_lock);
 167         if (crypto_default_rng_refcnt)
 168                 goto out;
 169
 170         crypto_free_rng(crypto_default_rng);
 171         crypto_default_rng = NULL;
 172
 173         err = 0;
 174
 175 out:
 176         mutex_unlock(&crypto_default_rng_lock);
 177
 178         return err;
 179 }
 180 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
 181 #endif
 182
 183 int crypto_register_rng(struct rng_alg *alg)
 184 {
 185         struct crypto_alg *base = &alg->base;
 186
 187         if (alg->seedsize > PAGE_SIZE / 8)
 188                 return -EINVAL;
 189
 190         base->cra_type = &crypto_rng_type;
 191         base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
 192         base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
 193
 194         return crypto_register_alg(base);
 195 }
 196 EXPORT_SYMBOL_GPL(crypto_register_rng);
 197
 198 void crypto_unregister_rng(struct rng_alg *alg)
 199 {
 200         crypto_unregister_alg(&alg->base);
 201 }
 202 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
 203
 204 int crypto_register_rngs(struct rng_alg *algs, int count)
 205 {
 206         int i, ret;
 207
 208         for (i = 0; i < count; i++) {
 209                 ret = crypto_register_rng(algs + i);
 210                 if (ret)
 211                         goto err;
 212         }
 213
 214         return 0;
 215
 216 err:
 217         for (--i; i >= 0; --i)
 218                 crypto_unregister_rng(algs + i);
 219
 220         return ret;
 221 }
 222 EXPORT_SYMBOL_GPL(crypto_register_rngs);
 223
 224 void crypto_unregister_rngs(struct rng_alg *algs, int count)
 225 {
 226         int i;
 227
 228         for (i = count - 1; i >= 0; --i)
 229                 crypto_unregister_rng(algs + i);
 230 }
 231 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
 232
 233 MODULE_LICENSE("GPL");
 234 MODULE_DESCRIPTION("Random Number Generator");