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