LXR linux/crypto/rng.c

   1/*
   2 * Cryptographic API.
   3 *
   4 * RNG operations.
   5 *
   6 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
   7 *
   8 * This program is free software; you can redistribute it and/or modify it
   9 * under the terms of the GNU General Public License as published by the Free
  10 * Software Foundation; either version 2 of the License, or (at your option)
  11 * any later version.
  12 *
  13 */
  14
  15#include <asm/atomic.h>
  16#include <crypto/internal/rng.h>
  17#include <linux/err.h>
  18#include <linux/module.h>
  19#include <linux/mutex.h>
  20#include <linux/random.h>
  21#include <linux/seq_file.h>
  22#include <linux/string.h>
  23
  24static DEFINE_MUTEX(crypto_default_rng_lock);
  25struct crypto_rng *crypto_default_rng;
  26EXPORT_SYMBOL_GPL(crypto_default_rng);
  27static int crypto_default_rng_refcnt;
  28
  29static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
  30{
  31        u8 *buf = NULL;
  32        int err;
  33
  34        if (!seed && slen) {
  35                buf = kmalloc(slen, GFP_KERNEL);
  36                if (!buf)
  37                        return -ENOMEM;
  38
  39                get_random_bytes(buf, slen);
  40                seed = buf;
  41        }
  42
  43        err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);
  44
  45        kfree(buf);
  46        return err;
  47}
  48
  49static int crypto_init_rng_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
  50{
  51        struct rng_alg *alg = &tfm->__crt_alg->cra_rng;
  52        struct rng_tfm *ops = &tfm->crt_rng;
  53
  54        ops->rng_gen_random = alg->rng_make_random;
  55        ops->rng_reset = rngapi_reset;
  56
  57        return 0;
  58}
  59
  60static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  61        __attribute__ ((unused));
  62static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  63{
  64        seq_printf(m, "type         : rng\n");
  65        seq_printf(m, "seedsize     : %u\n", alg->cra_rng.seedsize);
  66}
  67
  68static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type,
  69                                       u32 mask)
  70{
  71        return alg->cra_ctxsize;
  72}
  73
  74const struct crypto_type crypto_rng_type = {
  75        .ctxsize = crypto_rng_ctxsize,
  76        .init = crypto_init_rng_ops,
  77#ifdef CONFIG_PROC_FS
  78        .show = crypto_rng_show,
  79#endif
  80};
  81EXPORT_SYMBOL_GPL(crypto_rng_type);
  82
  83int crypto_get_default_rng(void)
  84{
  85        struct crypto_rng *rng;
  86        int err;
  87
  88        mutex_lock(&crypto_default_rng_lock);
  89        if (!crypto_default_rng) {
  90                rng = crypto_alloc_rng("stdrng", 0, 0);
  91                err = PTR_ERR(rng);
  92                if (IS_ERR(rng))
  93                        goto unlock;
  94
  95                err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
  96                if (err) {
  97                        crypto_free_rng(rng);
  98                        goto unlock;
  99                }
 100
 101                crypto_default_rng = rng;
 102        }
 103
 104        crypto_default_rng_refcnt++;
 105        err = 0;
 106
 107unlock:
 108        mutex_unlock(&crypto_default_rng_lock);
 109
 110        return err;
 111}
 112EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 113
 114void crypto_put_default_rng(void)
 115{
 116        mutex_lock(&crypto_default_rng_lock);
 117        if (!--crypto_default_rng_refcnt) {
 118                crypto_free_rng(crypto_default_rng);
 119                crypto_default_rng = NULL;
 120        }
 121        mutex_unlock(&crypto_default_rng_lock);
 122}
 123EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 124
 125MODULE_LICENSE("GPL");
 126MODULE_DESCRIPTION("Random Number Generator");
 127