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         struct rng_alg *alg = crypto_rng_alg(tfm);
  34         u8 *buf = NULL;
  35         int err;
  36
  37         if (IS_ENABLED(CONFIG_CRYPTO_STATS))
  38                 atomic64_inc(&rng_get_stat(alg)->seed_cnt);
  39
  40         if (!seed && slen) {
  41                 buf = kmalloc(slen, GFP_KERNEL);
  42                 err = -ENOMEM;
  43                 if (!buf)
  44                         goto out;
  45
  46                 err = get_random_bytes_wait(buf, slen);
  47                 if (err)
  48                         goto free_buf;
  49                 seed = buf;
  50         }
  51
  52         err = alg->seed(tfm, seed, slen);
  53 free_buf:
  54         kfree_sensitive(buf);
  55 out:
  56         return crypto_rng_errstat(alg, err);
  57 }
  58 EXPORT_SYMBOL_GPL(crypto_rng_reset);
  59
  60 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
  61 {
  62         return 0;
  63 }
  64
  65 static unsigned int seedsize(struct crypto_alg *alg)
  66 {
  67         struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
  68
  69         return ralg->seedsize;
  70 }
  71
  72 static int __maybe_unused crypto_rng_report(
  73         struct sk_buff *skb, struct crypto_alg *alg)
  74 {
  75         struct crypto_report_rng rrng;
  76
  77         memset(&rrng, 0, sizeof(rrng));
  78
  79         strscpy(rrng.type, "rng", sizeof(rrng.type));
  80
  81         rrng.seedsize = seedsize(alg);
  82
  83         return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
  84 }
  85
  86 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  87         __maybe_unused;
  88 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  89 {
  90         seq_printf(m, "type         : rng\n");
  91         seq_printf(m, "seedsize     : %u\n", seedsize(alg));
  92 }
  93
  94 static int __maybe_unused crypto_rng_report_stat(
  95         struct sk_buff *skb, struct crypto_alg *alg)
  96 {
  97         struct rng_alg *rng = __crypto_rng_alg(alg);
  98         struct crypto_istat_rng *istat;
  99         struct crypto_stat_rng rrng;
 100
 101         istat = rng_get_stat(rng);
 102
 103         memset(&rrng, 0, sizeof(rrng));
 104
 105         strscpy(rrng.type, "rng", sizeof(rrng.type));
 106
 107         rrng.stat_generate_cnt = atomic64_read(&istat->generate_cnt);
 108         rrng.stat_generate_tlen = atomic64_read(&istat->generate_tlen);
 109         rrng.stat_seed_cnt = atomic64_read(&istat->seed_cnt);
 110         rrng.stat_err_cnt = atomic64_read(&istat->err_cnt);
 111
 112         return nla_put(skb, CRYPTOCFGA_STAT_RNG, sizeof(rrng), &rrng);
 113 }
 114
 115 static const struct crypto_type crypto_rng_type = {
 116         .extsize = crypto_alg_extsize,
 117         .init_tfm = crypto_rng_init_tfm,
 118 #ifdef CONFIG_PROC_FS
 119         .show = crypto_rng_show,
 120 #endif
 121 #if IS_ENABLED(CONFIG_CRYPTO_USER)
 122         .report = crypto_rng_report,
 123 #endif
 124 #ifdef CONFIG_CRYPTO_STATS
 125         .report_stat = crypto_rng_report_stat,
 126 #endif
 127         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
 128         .maskset = CRYPTO_ALG_TYPE_MASK,
 129         .type = CRYPTO_ALG_TYPE_RNG,
 130         .tfmsize = offsetof(struct crypto_rng, base),
 131 };
 132
 133 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
 134 {
 135         return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
 136 }
 137 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
 138
 139 int crypto_get_default_rng(void)
 140 {
 141         struct crypto_rng *rng;
 142         int err;
 143
 144         mutex_lock(&crypto_default_rng_lock);
 145         if (!crypto_default_rng) {
 146                 rng = crypto_alloc_rng("stdrng", 0, 0);
 147                 err = PTR_ERR(rng);
 148                 if (IS_ERR(rng))
 149                         goto unlock;
 150
 151                 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
 152                 if (err) {
 153                         crypto_free_rng(rng);
 154                         goto unlock;
 155                 }
 156
 157                 crypto_default_rng = rng;
 158         }
 159
 160         crypto_default_rng_refcnt++;
 161         err = 0;
 162
 163 unlock:
 164         mutex_unlock(&crypto_default_rng_lock);
 165
 166         return err;
 167 }
 168 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 169
 170 void crypto_put_default_rng(void)
 171 {
 172         mutex_lock(&crypto_default_rng_lock);
 173         crypto_default_rng_refcnt--;
 174         mutex_unlock(&crypto_default_rng_lock);
 175 }
 176 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 177
 178 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
 179 int crypto_del_default_rng(void)
 180 {
 181         int err = -EBUSY;
 182
 183         mutex_lock(&crypto_default_rng_lock);
 184         if (crypto_default_rng_refcnt)
 185                 goto out;
 186
 187         crypto_free_rng(crypto_default_rng);
 188         crypto_default_rng = NULL;
 189
 190         err = 0;
 191
 192 out:
 193         mutex_unlock(&crypto_default_rng_lock);
 194
 195         return err;
 196 }
 197 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
 198 #endif
 199
 200 int crypto_register_rng(struct rng_alg *alg)
 201 {
 202         struct crypto_istat_rng *istat = rng_get_stat(alg);
 203         struct crypto_alg *base = &alg->base;
 204
 205         if (alg->seedsize > PAGE_SIZE / 8)
 206                 return -EINVAL;
 207
 208         base->cra_type = &crypto_rng_type;
 209         base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
 210         base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
 211
 212         if (IS_ENABLED(CONFIG_CRYPTO_STATS))
 213                 memset(istat, 0, sizeof(*istat));
 214
 215         return crypto_register_alg(base);
 216 }
 217 EXPORT_SYMBOL_GPL(crypto_register_rng);
 218
 219 void crypto_unregister_rng(struct rng_alg *alg)
 220 {
 221         crypto_unregister_alg(&alg->base);
 222 }
 223 EXPORT_SYMBOL_GPL(crypto_unregister_rng);
 224
 225 int crypto_register_rngs(struct rng_alg *algs, int count)
 226 {
 227         int i, ret;
 228
 229         for (i = 0; i < count; i++) {
 230                 ret = crypto_register_rng(algs + i);
 231                 if (ret)
 232                         goto err;
 233         }
 234
 235         return 0;
 236
 237 err:
 238         for (--i; i >= 0; --i)
 239                 crypto_unregister_rng(algs + i);
 240
 241         return ret;
 242 }
 243 EXPORT_SYMBOL_GPL(crypto_register_rngs);
 244
 245 void crypto_unregister_rngs(struct rng_alg *algs, int count)
 246 {
 247         int i;
 248
 249         for (i = count - 1; i >= 0; --i)
 250                 crypto_unregister_rng(algs + i);
 251 }
 252 EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
 253
 254 MODULE_LICENSE("GPL");
 255 MODULE_DESCRIPTION("Random Number Generator");