Quelle rng.c Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Cryptographic API.
*
* RNG operations.
*
* Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
* Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
*/

#include <crypto/internal/rng.h>
#include <linux/atomic.h>
#include <linux/cryptouser.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <net/netlink.h>

#include "internal.h"

static DEFINE_MUTEX(crypto_default_rng_lock);
struct crypto_rng *crypto_default_rng;
EXPORT_SYMBOL_GPL(crypto_default_rng);
static int crypto_default_rng_refcnt;

int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
{
u8 *buf = NULL;
int err;

if (!seed && slen) {
  buf = kmalloc(slen, GFP_KERNEL);
  if (!buf)
   return -ENOMEM;

  err = get_random_bytes_wait(buf, slen);
  if (err)
   goto out;
  seed = buf;
}

err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
out:
kfree_sensitive(buf);
return err;
}
EXPORT_SYMBOL_GPL(crypto_rng_reset);

static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
{
return 0;
}

static unsigned int seedsize(struct crypto_alg *alg)
{
struct rng_alg *ralg = container_of(alg, struct rng_alg, base);

return ralg->seedsize;
}

static int __maybe_unused crypto_rng_report(
struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_rng rrng;

memset(&rrng, 0, sizeof(rrng));

strscpy(rrng.type, "rng", sizeof(rrng.type));

rrng.seedsize = seedsize(alg);

return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
}

static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
__maybe_unused;
static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
{
seq_printf(m, "type : rng\n");
seq_printf(m, "seedsize : %u\n", seedsize(alg));
}

static const struct crypto_type crypto_rng_type = {
.extsize = crypto_alg_extsize,
.init_tfm = crypto_rng_init_tfm,
#ifdef CONFIG_PROC_FS
.show = crypto_rng_show,
#endif
#if IS_ENABLED(CONFIG_CRYPTO_USER)
.report = crypto_rng_report,
#endif
.maskclear = ~CRYPTO_ALG_TYPE_MASK,
.maskset = CRYPTO_ALG_TYPE_MASK,
.type = CRYPTO_ALG_TYPE_RNG,
.tfmsize = offsetof(struct crypto_rng, base),
.algsize = offsetof(struct rng_alg, base),
};

struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
{
return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_rng);

int crypto_get_default_rng(void)
{
struct crypto_rng *rng;
int err;

mutex_lock(&crypto_default_rng_lock);
if (!crypto_default_rng) {
  rng = crypto_alloc_rng("stdrng", 0, 0);
  err = PTR_ERR(rng);
  if (IS_ERR(rng))
   goto unlock;

  err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
  if (err) {
   crypto_free_rng(rng);
   goto unlock;
  }

  crypto_default_rng = rng;
}

crypto_default_rng_refcnt++;
err = 0;

unlock:
mutex_unlock(&crypto_default_rng_lock);

return err;
}
EXPORT_SYMBOL_GPL(crypto_get_default_rng);

void crypto_put_default_rng(void)
{
mutex_lock(&crypto_default_rng_lock);
crypto_default_rng_refcnt--;
mutex_unlock(&crypto_default_rng_lock);
}
EXPORT_SYMBOL_GPL(crypto_put_default_rng);

#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
int crypto_del_default_rng(void)
{
int err = -EBUSY;

mutex_lock(&crypto_default_rng_lock);
if (crypto_default_rng_refcnt)
  goto out;

crypto_free_rng(crypto_default_rng);
crypto_default_rng = NULL;

err = 0;

out:
mutex_unlock(&crypto_default_rng_lock);

return err;
}
EXPORT_SYMBOL_GPL(crypto_del_default_rng);
#endif

static void rng_default_set_ent(struct crypto_rng *tfm, const u8 *data,
    unsigned int len)
{
}

int crypto_register_rng(struct rng_alg *alg)
{
struct crypto_alg *base = &alg->base;

if (alg->seedsize > PAGE_SIZE / 8)
  return -EINVAL;

base->cra_type = &crypto_rng_type;
base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
base->cra_flags |= CRYPTO_ALG_TYPE_RNG;

if (!alg->set_ent)
  alg->set_ent = rng_default_set_ent;

return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_rng);

void crypto_unregister_rng(struct rng_alg *alg)
{
crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_rng);

int crypto_register_rngs(struct rng_alg *algs, int count)
{
int i, ret;

for (i = 0; i < count; i++) {
  ret = crypto_register_rng(algs + i);
  if (ret)
   goto err;
}

return 0;

err:
for (--i; i >= 0; --i)
  crypto_unregister_rng(algs + i);

return ret;
}
EXPORT_SYMBOL_GPL(crypto_register_rngs);

void crypto_unregister_rngs(struct rng_alg *algs, int count)
{
int i;

for (i = count - 1; i >= 0; --i)
  crypto_unregister_rng(algs + i);
}
EXPORT_SYMBOL_GPL(crypto_unregister_rngs);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Random Number Generator");

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