crypto/rng.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Cryptographic API.
   4  *
   5  * RNG operations.
   6  *
   7  * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
   8  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
   9  */
  10
  11 #include <linux/atomic.h>
  12 #include <crypto/internal/rng.h>
  13 #include <linux/err.h>
  14 #include <linux/module.h>
  15 #include <linux/mutex.h>
  16 #include <linux/random.h>
  17 #include <linux/seq_file.h>
  18 #include <linux/slab.h>
  19 #include <linux/string.h>
  20 #include <linux/cryptouser.h>
  21 #include <linux/compiler.h>
  22 #include <net/netlink.h>
  23
  24 #include "internal.h"
  25
  26 static DEFINE_MUTEX(crypto_default_rng_lock);
  27 struct crypto_rng *crypto_default_rng;
  28 EXPORT_SYMBOL_GPL(crypto_default_rng);
  29 static int crypto_default_rng_refcnt;
  30
  31 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
  32 {
  33         struct crypto_alg *alg = tfm->base.__crt_alg;
  34         u8 *buf = NULL;
  35         int err;
  36
  37         crypto_stats_get(alg);
  38         if (!seed && slen) {
  39                 buf = kmalloc(slen, GFP_KERNEL);
  40                 if (!buf)
  41                         return -ENOMEM;
  42
  43                 err = get_random_bytes_wait(buf, slen);
  44                 if (err)
  45                         goto out;
  46                 seed = buf;
  47         }
  48
  49         err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
  50         crypto_stats_rng_seed(alg, err);
  51 out:
  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         memset(&rrng, 0, sizeof(rrng));
  75
  76         strscpy(rrng.type, "rng", sizeof(rrng.type));
  77
  78         rrng.seedsize = seedsize(alg);
  79
  80         return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
  81 }
  82 #else
  83 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  84 {
  85         return -ENOSYS;
  86 }
  87 #endif
  88
  89 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  90         __maybe_unused;
  91 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  92 {
  93         seq_printf(m, "type         : rng\n");
  94         seq_printf(m, "seedsize     : %u\n", seedsize(alg));
  95 }
  96
  97 static const struct crypto_type crypto_rng_type = {
  98         .extsize = crypto_alg_extsize,
  99         .init_tfm = crypto_rng_init_tfm,
 100 #ifdef CONFIG_PROC_FS
 101         .show = crypto_rng_show,
 102 #endif
 103         .report = crypto_rng_report,
 104         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
 105         .maskset = CRYPTO_ALG_TYPE_MASK,
 106         .type = CRYPTO_ALG_TYPE_RNG,
 107         .tfmsize = offsetof(struct crypto_rng, base),
 108 };
 109
 110 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
 111 {
 112         return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
 113 }
 114 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
 115
 116 int crypto_get_default_rng(void)
 117 {
 118         struct crypto_rng *rng;
 119         int err;
 120
 121         mutex_lock(&crypto_default_rng_lock);
 122         if (!crypto_default_rng) {
 123                 rng = crypto_alloc_rng("stdrng", 0, 0);
 124                 err = PTR_ERR(rng);
 125                 if (IS_ERR(rng))
 126                         goto unlock;
 127
 128                 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
 129                 if (err) {
 130                         crypto_free_rng(rng);
 131                         goto unlock;
 132                 }
 133
 134                 crypto_default_rng = rng;
 135         }
 136
 137         crypto_default_rng_refcnt++;
 138         err = 0;
 139
 140 unlock:
 141         mutex_unlock(&crypto_default_rng_lock);
 142
 143         return err;
 144 }
 145 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 146
 147 void crypto_put_default_rng(void)
 148 {
 149         mutex_lock(&crypto_default_rng_lock);
 150         crypto_default_rng_refcnt--;
 151         mutex_unlock(&crypto_default_rng_lock);
 152 }
 153 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 154
 155 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
 156 int crypto_del_default_rng(void)
 157 {
 158         int err = -EBUSY;
 159
 160         mutex_lock(&crypto_default_rng_lock);
 161         if (crypto_default_rng_refcnt)
 162                 goto out;
 163
 164         crypto_free_rng(crypto_default_rng);
 165         crypto_default_rng = NULL;
 166
 167         err = 0;
 168
 169 out:
 170         mutex_unlock(&crypto_default_rng_lock);
 171
 172         return err;
 173 }
 174 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
 175 #endif
 176
 177 int crypto_register_rng(struct rng_alg *alg)
 178 {
 179         struct crypto_alg *base = &alg->base;
 180
 181         if (alg->seedsize > PAGE_SIZE / 8)
 182                 return -EINVAL;
 183
 184         base->cra_type = &crypto_rng_type;
 185         base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
 186         base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
 187
 188         return crypto_register_alg(base);
 189 }
 190 EXPORT_SYMBOL_GPL(crypto_register_rng);
 191
 192 void crypto_unregister_rng(struct rng_alg *alg)
 193 {
 194         crypto_unregister_alg(&alg->base);
 195 }
 196 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
 197
 198 int crypto_register_rngs(struct rng_alg *algs, int count)
 199 {
 200         int i, ret;
 201
 202         for (i = 0; i < count; i++) {
 203                 ret = crypto_register_rng(algs + i);
 204                 if (ret)
 205                         goto err;
 206         }
 207
 208         return 0;
 209
 210 err:
 211         for (--i; i >= 0; --i)
 212                 crypto_unregister_rng(algs + i);
 213
 214         return ret;
 215 }
 216 EXPORT_SYMBOL_GPL(crypto_register_rngs);
 217
 218 void crypto_unregister_rngs(struct rng_alg *algs, int count)
 219 {
 220         int i;
 221
 222         for (i = count - 1; i >= 0; --i)
 223                 crypto_unregister_rng(algs + i);
 224 }
 225 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
 226
 227 MODULE_LICENSE("GPL");
 228 MODULE_DESCRIPTION("Random Number Generator");