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 <crypto/internal/rng.h>
  12 #include <linux/atomic.h>
  13 #include <linux/cryptouser.h>
  14 #include <linux/err.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/mutex.h>
  18 #include <linux/random.h>
  19 #include <linux/seq_file.h>
  20 #include <linux/slab.h>
  21 #include <linux/string.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         u8 *buf = NULL;
  34         int err;
  35
  36         if (!seed && slen) {
  37                 buf = kmalloc(slen, GFP_KERNEL);
  38                 if (!buf)
  39                         return -ENOMEM;
  40
  41                 err = get_random_bytes_wait(buf, slen);
  42                 if (err)
  43                         goto out;
  44                 seed = buf;
  45         }
  46
  47         err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
  48 out:
  49         kfree_sensitive(buf);
  50         return err;
  51 }
  52 EXPORT_SYMBOL_GPL(crypto_rng_reset);
  53
  54 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
  55 {
  56         return 0;
  57 }
  58
  59 static unsigned int seedsize(struct crypto_alg *alg)
  60 {
  61         struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
  62
  63         return ralg->seedsize;
  64 }
  65
  66 static int __maybe_unused crypto_rng_report(
  67         struct sk_buff *skb, struct crypto_alg *alg)
  68 {
  69         struct crypto_report_rng rrng;
  70
  71         memset(&rrng, 0, sizeof(rrng));
  72
  73         strscpy(rrng.type, "rng", sizeof(rrng.type));
  74
  75         rrng.seedsize = seedsize(alg);
  76
  77         return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
  78 }
  79
  80 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  81         __maybe_unused;
  82 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  83 {
  84         seq_printf(m, "type         : rng\n");
  85         seq_printf(m, "seedsize     : %u\n", seedsize(alg));
  86 }
  87
  88 static const struct crypto_type crypto_rng_type = {
  89         .extsize = crypto_alg_extsize,
  90         .init_tfm = crypto_rng_init_tfm,
  91 #ifdef CONFIG_PROC_FS
  92         .show = crypto_rng_show,
  93 #endif
  94 #if IS_ENABLED(CONFIG_CRYPTO_USER)
  95         .report = crypto_rng_report,
  96 #endif
  97         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
  98         .maskset = CRYPTO_ALG_TYPE_MASK,
  99         .type = CRYPTO_ALG_TYPE_RNG,
 100         .tfmsize = offsetof(struct crypto_rng, base),
 101 };
 102
 103 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
 104 {
 105         return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
 106 }
 107 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
 108
 109 int crypto_get_default_rng(void)
 110 {
 111         struct crypto_rng *rng;
 112         int err;
 113
 114         mutex_lock(&crypto_default_rng_lock);
 115         if (!crypto_default_rng) {
 116                 rng = crypto_alloc_rng("stdrng", 0, 0);
 117                 err = PTR_ERR(rng);
 118                 if (IS_ERR(rng))
 119                         goto unlock;
 120
 121                 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
 122                 if (err) {
 123                         crypto_free_rng(rng);
 124                         goto unlock;
 125                 }
 126
 127                 crypto_default_rng = rng;
 128         }
 129
 130         crypto_default_rng_refcnt++;
 131         err = 0;
 132
 133 unlock:
 134         mutex_unlock(&crypto_default_rng_lock);
 135
 136         return err;
 137 }
 138 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 139
 140 void crypto_put_default_rng(void)
 141 {
 142         mutex_lock(&crypto_default_rng_lock);
 143         crypto_default_rng_refcnt--;
 144         mutex_unlock(&crypto_default_rng_lock);
 145 }
 146 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 147
 148 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
 149 int crypto_del_default_rng(void)
 150 {
 151         int err = -EBUSY;
 152
 153         mutex_lock(&crypto_default_rng_lock);
 154         if (crypto_default_rng_refcnt)
 155                 goto out;
 156
 157         crypto_free_rng(crypto_default_rng);
 158         crypto_default_rng = NULL;
 159
 160         err = 0;
 161
 162 out:
 163         mutex_unlock(&crypto_default_rng_lock);
 164
 165         return err;
 166 }
 167 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
 168 #endif
 169
 170 int crypto_register_rng(struct rng_alg *alg)
 171 {
 172         struct crypto_alg *base = &alg->base;
 173
 174         if (alg->seedsize > PAGE_SIZE / 8)
 175                 return -EINVAL;
 176
 177         base->cra_type = &crypto_rng_type;
 178         base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
 179         base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
 180
 181         return crypto_register_alg(base);
 182 }
 183 EXPORT_SYMBOL_GPL(crypto_register_rng);
 184
 185 void crypto_unregister_rng(struct rng_alg *alg)
 186 {
 187         crypto_unregister_alg(&alg->base);
 188 }
 189 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
 190
 191 int crypto_register_rngs(struct rng_alg *algs, int count)
 192 {
 193         int i, ret;
 194
 195         for (i = 0; i < count; i++) {
 196                 ret = crypto_register_rng(algs + i);
 197                 if (ret)
 198                         goto err;
 199         }
 200
 201         return 0;
 202
 203 err:
 204         for (--i; i >= 0; --i)
 205                 crypto_unregister_rng(algs + i);
 206
 207         return ret;
 208 }
 209 EXPORT_SYMBOL_GPL(crypto_register_rngs);
 210
 211 void crypto_unregister_rngs(struct rng_alg *algs, int count)
 212 {
 213         int i;
 214
 215         for (i = count - 1; i >= 0; --i)
 216                 crypto_unregister_rng(algs + i);
 217 }
 218 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
 219
 220 MODULE_LICENSE("GPL");
 221 MODULE_DESCRIPTION("Random Number Generator");