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