linux/crypto/rng.c
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   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
  26static DEFINE_MUTEX(crypto_default_rng_lock);
  27struct crypto_rng *crypto_default_rng;
  28EXPORT_SYMBOL_GPL(crypto_default_rng);
  29static int crypto_default_rng_refcnt;
  30
  31int 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        if (!seed && slen) {
  38                buf = kmalloc(slen, GFP_KERNEL);
  39                if (!buf)
  40                        return -ENOMEM;
  41
  42                err = get_random_bytes_wait(buf, slen);
  43                if (err)
  44                        goto out;
  45                seed = buf;
  46        }
  47
  48        crypto_stats_get(alg);
  49        err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
  50        crypto_stats_rng_seed(alg, err);
  51out:
  52        kfree_sensitive(buf);
  53        return err;
  54}
  55EXPORT_SYMBOL_GPL(crypto_rng_reset);
  56
  57static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
  58{
  59        return 0;
  60}
  61
  62static 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
  70static 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
  83static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  84{
  85        return -ENOSYS;
  86}
  87#endif
  88
  89static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  90        __maybe_unused;
  91static 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
  97static 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
 110struct 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}
 114EXPORT_SYMBOL_GPL(crypto_alloc_rng);
 115
 116int 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
 140unlock:
 141        mutex_unlock(&crypto_default_rng_lock);
 142
 143        return err;
 144}
 145EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 146
 147void 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}
 153EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 154
 155#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
 156int 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
 169out:
 170        mutex_unlock(&crypto_default_rng_lock);
 171
 172        return err;
 173}
 174EXPORT_SYMBOL_GPL(crypto_del_default_rng);
 175#endif
 176
 177int 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}
 190EXPORT_SYMBOL_GPL(crypto_register_rng);
 191
 192void crypto_unregister_rng(struct rng_alg *alg)
 193{
 194        crypto_unregister_alg(&alg->base);
 195}
 196EXPORT_SYMBOL_GPL(crypto_unregister_rng);
 197
 198int 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
 210err:
 211        for (--i; i >= 0; --i)
 212                crypto_unregister_rng(algs + i);
 213
 214        return ret;
 215}
 216EXPORT_SYMBOL_GPL(crypto_register_rngs);
 217
 218void 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}
 225EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
 226
 227MODULE_LICENSE("GPL");
 228MODULE_DESCRIPTION("Random Number Generator");
 229
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