209 lines
6.0 KiB
C
209 lines
6.0 KiB
C
|
/*
|
||
|
|
* Non-physical true random number generator based on timing jitter --
|
||
|
|
* Linux Kernel Crypto API specific code
|
||
|
|
*
|
||
|
|
* Copyright Stephan Mueller <smueller@chronox.de>, 2015
|
||
|
|
*
|
||
|
|
* Redistribution and use in source and binary forms, with or without
|
||
|
|
* modification, are permitted provided that the following conditions
|
||
|
|
* are met:
|
||
|
|
* 1. Redistributions of source code must retain the above copyright
|
||
|
|
* notice, and the entire permission notice in its entirety,
|
||
|
|
* including the disclaimer of warranties.
|
||
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
* notice, this list of conditions and the following disclaimer in the
|
||
|
|
* documentation and/or other materials provided with the distribution.
|
||
|
|
* 3. The name of the author may not be used to endorse or promote
|
||
|
|
* products derived from this software without specific prior
|
||
|
|
* written permission.
|
||
|
|
*
|
||
|
|
* ALTERNATIVELY, this product may be distributed under the terms of
|
||
|
|
* the GNU General Public License, in which case the provisions of the GPL2 are
|
||
|
|
* required INSTEAD OF the above restrictions. (This clause is
|
||
|
|
* necessary due to a potential bad interaction between the GPL and
|
||
|
|
* the restrictions contained in a BSD-style copyright.)
|
||
|
|
*
|
||
|
|
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
|
||
|
|
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
||
|
|
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
|
||
|
|
* WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
|
||
|
|
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||
|
|
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
|
||
|
|
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
|
||
|
|
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
|
||
|
|
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||
|
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
|
||
|
|
* USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
|
||
|
|
* DAMAGE.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/slab.h>
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/fips.h>
|
||
|
|
#include <linux/time.h>
|
||
|
|
#include <linux/crypto.h>
|
||
|
|
#include <crypto/internal/rng.h>
|
||
|
|
|
||
|
|
struct rand_data;
|
||
|
|
int jent_read_entropy(struct rand_data *ec, unsigned char *data,
|
||
|
|
unsigned int len);
|
||
|
|
int jent_entropy_init(void);
|
||
|
|
struct rand_data *jent_entropy_collector_alloc(unsigned int osr,
|
||
|
|
unsigned int flags);
|
||
|
|
void jent_entropy_collector_free(struct rand_data *entropy_collector);
|
||
|
|
|
||
|
|
/***************************************************************************
|
||
|
|
* Helper function
|
||
|
|
***************************************************************************/
|
||
|
|
|
||
|
|
__u64 jent_rol64(__u64 word, unsigned int shift)
|
||
|
|
{
|
||
|
|
return rol64(word, shift);
|
||
|
|
}
|
||
|
|
|
||
|
|
void *jent_zalloc(unsigned int len)
|
||
|
|
{
|
||
|
|
return kzalloc(len, GFP_KERNEL);
|
||
|
|
}
|
||
|
|
|
||
|
|
void jent_zfree(void *ptr)
|
||
|
|
{
|
||
|
|
kzfree(ptr);
|
||
|
|
}
|
||
|
|
|
||
|
|
int jent_fips_enabled(void)
|
||
|
|
{
|
||
|
|
return fips_enabled;
|
||
|
|
}
|
||
|
|
|
||
|
|
void jent_panic(char *s)
|
||
|
|
{
|
||
|
|
panic("%s", s);
|
||
|
|
}
|
||
|
|
|
||
|
|
void jent_memcpy(void *dest, const void *src, unsigned int n)
|
||
|
|
{
|
||
|
|
memcpy(dest, src, n);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Obtain a high-resolution time stamp value. The time stamp is used to measure
|
||
|
|
* the execution time of a given code path and its variations. Hence, the time
|
||
|
|
* stamp must have a sufficiently high resolution.
|
||
|
|
*
|
||
|
|
* Note, if the function returns zero because a given architecture does not
|
||
|
|
* implement a high-resolution time stamp, the RNG code's runtime test
|
||
|
|
* will detect it and will not produce output.
|
||
|
|
*/
|
||
|
|
void jent_get_nstime(__u64 *out)
|
||
|
|
{
|
||
|
|
__u64 tmp = 0;
|
||
|
|
|
||
|
|
tmp = random_get_entropy();
|
||
|
|
|
||
|
|
/*
|
||
|
|
* If random_get_entropy does not return a value, i.e. it is not
|
||
|
|
* implemented for a given architecture, use a clock source.
|
||
|
|
* hoping that there are timers we can work with.
|
||
|
|
*/
|
||
|
|
if (tmp == 0)
|
||
|
|
tmp = ktime_get_ns();
|
||
|
|
|
||
|
|
*out = tmp;
|
||
|
|
}
|
||
|
|
|
||
|
|
/***************************************************************************
|
||
|
|
* Kernel crypto API interface
|
||
|
|
***************************************************************************/
|
||
|
|
|
||
|
|
struct jitterentropy {
|
||
|
|
spinlock_t jent_lock;
|
||
|
|
struct rand_data *entropy_collector;
|
||
|
|
};
|
||
|
|
|
||
|
|
static int jent_kcapi_init(struct crypto_tfm *tfm)
|
||
|
|
{
|
||
|
|
struct jitterentropy *rng = crypto_tfm_ctx(tfm);
|
||
|
|
int ret = 0;
|
||
|
|
|
||
|
|
rng->entropy_collector = jent_entropy_collector_alloc(1, 0);
|
||
|
|
if (!rng->entropy_collector)
|
||
|
|
ret = -ENOMEM;
|
||
|
|
|
||
|
|
spin_lock_init(&rng->jent_lock);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void jent_kcapi_cleanup(struct crypto_tfm *tfm)
|
||
|
|
{
|
||
|
|
struct jitterentropy *rng = crypto_tfm_ctx(tfm);
|
||
|
|
|
||
|
|
spin_lock(&rng->jent_lock);
|
||
|
|
if (rng->entropy_collector)
|
||
|
|
jent_entropy_collector_free(rng->entropy_collector);
|
||
|
|
rng->entropy_collector = NULL;
|
||
|
|
spin_unlock(&rng->jent_lock);
|
||
|
|
}
|
||
|
|
|
||
|
|
static int jent_kcapi_random(struct crypto_rng *tfm,
|
||
|
|
const u8 *src, unsigned int slen,
|
||
|
|
u8 *rdata, unsigned int dlen)
|
||
|
|
{
|
||
|
|
struct jitterentropy *rng = crypto_rng_ctx(tfm);
|
||
|
|
int ret = 0;
|
||
|
|
|
||
|
|
spin_lock(&rng->jent_lock);
|
||
|
|
ret = jent_read_entropy(rng->entropy_collector, rdata, dlen);
|
||
|
|
spin_unlock(&rng->jent_lock);
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int jent_kcapi_reset(struct crypto_rng *tfm,
|
||
|
|
const u8 *seed, unsigned int slen)
|
||
|
|
{
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static struct rng_alg jent_alg = {
|
||
|
|
.generate = jent_kcapi_random,
|
||
|
|
.seed = jent_kcapi_reset,
|
||
|
|
.seedsize = 0,
|
||
|
|
.base = {
|
||
|
|
.cra_name = "jitterentropy_rng",
|
||
|
|
.cra_driver_name = "jitterentropy_rng",
|
||
|
|
.cra_priority = 100,
|
||
|
|
.cra_ctxsize = sizeof(struct jitterentropy),
|
||
|
|
.cra_module = THIS_MODULE,
|
||
|
|
.cra_init = jent_kcapi_init,
|
||
|
|
.cra_exit = jent_kcapi_cleanup,
|
||
|
|
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
static int __init jent_mod_init(void)
|
||
|
|
{
|
||
|
|
int ret = 0;
|
||
|
|
|
||
|
|
ret = jent_entropy_init();
|
||
|
|
if (ret) {
|
||
|
|
pr_info("jitterentropy: Initialization failed with host not compliant with requirements: %d\n", ret);
|
||
|
|
return -EFAULT;
|
||
|
|
}
|
||
|
|
return crypto_register_rng(&jent_alg);
|
||
|
|
}
|
||
|
|
|
||
|
|
static void __exit jent_mod_exit(void)
|
||
|
|
{
|
||
|
|
crypto_unregister_rng(&jent_alg);
|
||
|
|
}
|
||
|
|
|
||
|
|
module_init(jent_mod_init);
|
||
|
|
module_exit(jent_mod_exit);
|
||
|
|
|
||
|
|
MODULE_LICENSE("Dual BSD/GPL");
|
||
|
|
MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
|
||
|
|
MODULE_DESCRIPTION("Non-physical True Random Number Generator based on CPU Jitter");
|
||
|
|
MODULE_ALIAS_CRYPTO("jitterentropy_rng");
|