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         struct crypto_alg *alg = tfm->base.__crt_alg;
  39         u8 *buf = NULL;
  40         int err;
  41
  42         crypto_stats_get(alg);
  43         if (!seed && slen) {
  44                 buf = kmalloc(slen, GFP_KERNEL);
  45                 if (!buf)
  46                         return -ENOMEM;
  47
  48                 err = get_random_bytes_wait(buf, slen);
  49                 if (err)
  50                         goto out;
  51                 seed = buf;
  52         }
  53
  54         err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
  55         crypto_stats_rng_seed(alg, err);
  56 out:
  57         kzfree(buf);
  58         return err;
  59 }
  60 EXPORT_SYMBOL_GPL(crypto_rng_reset);
  61
  62 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
  63 {
  64         return 0;
  65 }
  66
  67 static unsigned int seedsize(struct crypto_alg *alg)
  68 {
  69         struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
  70
  71         return ralg->seedsize;
  72 }
  73
  74 #ifdef CONFIG_NET
  75 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  76 {
  77         struct crypto_report_rng rrng;
  78
  79         memset(&rrng, 0, sizeof(rrng));
  80
  81         strscpy(rrng.type, "rng", sizeof(rrng.type));
  82
  83         rrng.seedsize = seedsize(alg);
  84
  85         return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
  86 }
  87 #else
  88 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  89 {
  90         return -ENOSYS;
  91 }
  92 #endif
  93
  94 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  95         __maybe_unused;
  96 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  97 {
  98         seq_printf(m, "type         : rng\n");
  99         seq_printf(m, "seedsize     : %u\n", seedsize(alg));
 100 }
 101
 102 static const struct crypto_type crypto_rng_type = {
 103         .extsize = crypto_alg_extsize,
 104         .init_tfm = crypto_rng_init_tfm,
 105 #ifdef CONFIG_PROC_FS
 106         .show = crypto_rng_show,
 107 #endif
 108         .report = crypto_rng_report,
 109         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
 110         .maskset = CRYPTO_ALG_TYPE_MASK,
 111         .type = CRYPTO_ALG_TYPE_RNG,
 112         .tfmsize = offsetof(struct crypto_rng, base),
 113 };
 114
 115 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
 116 {
 117         return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
 118 }
 119 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
 120
 121 int crypto_get_default_rng(void)
 122 {
 123         struct crypto_rng *rng;
 124         int err;
 125
 126         mutex_lock(&crypto_default_rng_lock);
 127         if (!crypto_default_rng) {
 128                 rng = crypto_alloc_rng("stdrng", 0, 0);
 129                 err = PTR_ERR(rng);
 130                 if (IS_ERR(rng))
 131                         goto unlock;
 132
 133                 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
 134                 if (err) {
 135                         crypto_free_rng(rng);
 136                         goto unlock;
 137                 }
 138
 139                 crypto_default_rng = rng;
 140         }
 141
 142         crypto_default_rng_refcnt++;
 143         err = 0;
 144
 145 unlock:
 146         mutex_unlock(&crypto_default_rng_lock);
 147
 148         return err;
 149 }
 150 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 151
 152 void crypto_put_default_rng(void)
 153 {
 154         mutex_lock(&crypto_default_rng_lock);
 155         crypto_default_rng_refcnt--;
 156         mutex_unlock(&crypto_default_rng_lock);
 157 }
 158 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 159
 160 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
 161 int crypto_del_default_rng(void)
 162 {
 163         int err = -EBUSY;
 164
 165         mutex_lock(&crypto_default_rng_lock);
 166         if (crypto_default_rng_refcnt)
 167                 goto out;
 168
 169         crypto_free_rng(crypto_default_rng);
 170         crypto_default_rng = NULL;
 171
 172         err = 0;
 173
 174 out:
 175         mutex_unlock(&crypto_default_rng_lock);
 176
 177         return err;
 178 }
 179 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
 180 #endif
 181
 182 int crypto_register_rng(struct rng_alg *alg)
 183 {
 184         struct crypto_alg *base = &alg->base;
 185
 186         if (alg->seedsize > PAGE_SIZE / 8)
 187                 return -EINVAL;
 188
 189         base->cra_type = &crypto_rng_type;
 190         base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
 191         base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
 192
 193         return crypto_register_alg(base);
 194 }
 195 EXPORT_SYMBOL_GPL(crypto_register_rng);
 196
 197 void crypto_unregister_rng(struct rng_alg *alg)
 198 {
 199         crypto_unregister_alg(&alg->base);
 200 }
 201 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
 202
 203 int crypto_register_rngs(struct rng_alg *algs, int count)
 204 {
 205         int i, ret;
 206
 207         for (i = 0; i < count; i++) {
 208                 ret = crypto_register_rng(algs + i);
 209                 if (ret)
 210                         goto err;
 211         }
 212
 213         return 0;
 214
 215 err:
 216         for (--i; i >= 0; --i)
 217                 crypto_unregister_rng(algs + i);
 218
 219         return ret;
 220 }
 221 EXPORT_SYMBOL_GPL(crypto_register_rngs);
 222
 223 void crypto_unregister_rngs(struct rng_alg *algs, int count)
 224 {
 225         int i;
 226
 227         for (i = count - 1; i >= 0; --i)
 228                 crypto_unregister_rng(algs + i);
 229 }
 230 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
 231
 232 MODULE_LICENSE("GPL");
 233 MODULE_DESCRIPTION("Random Number Generator");