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tag: v2.6.28-rc4
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/*
* Cryptographic API.
*
* RNG operations.
*
* Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/

#include <asm/atomic.h>
#include <crypto/internal/rng.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/string.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;

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

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

get_random_bytes(buf, slen);
seed = buf;
}

err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);

kfree(buf);
return err;
}

static int crypto_init_rng_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
{
struct rng_alg *alg = &tfm->__crt_alg->cra_rng;
struct rng_tfm *ops = &tfm->crt_rng;

ops->rng_gen_random = alg->rng_make_random;
ops->rng_reset = rngapi_reset;

return 0;
}

static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
__attribute__ ((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", alg->cra_rng.seedsize);
}

static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type,
u32 mask)
{
return alg->cra_ctxsize;
}

const struct crypto_type crypto_rng_type = {
.ctxsize = crypto_rng_ctxsize,
.init = crypto_init_rng_ops,
#ifdef CONFIG_PROC_FS
.show = crypto_rng_show,
#endif
};
EXPORT_SYMBOL_GPL(crypto_rng_type);

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);
if (!--crypto_default_rng_refcnt) {
crypto_free_rng(crypto_default_rng);
crypto_default_rng = NULL;
}
mutex_unlock(&crypto_default_rng_lock);
}
EXPORT_SYMBOL_GPL(crypto_put_default_rng);

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