forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
217 lines
6.1 KiB
217 lines
6.1 KiB
/* |
|
* Non-physical true random number generator based on timing jitter -- |
|
* Linux Kernel Crypto API specific code |
|
* |
|
* Copyright Stephan Mueller <[email protected]>, 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/kernel.h> |
|
#include <linux/module.h> |
|
#include <linux/slab.h> |
|
#include <linux/time.h> |
|
#include <crypto/internal/rng.h> |
|
|
|
#include "jitterentropy.h" |
|
|
|
/*************************************************************************** |
|
* Helper function |
|
***************************************************************************/ |
|
|
|
void *jent_zalloc(unsigned int len) |
|
{ |
|
return kzalloc(len, GFP_KERNEL); |
|
} |
|
|
|
void jent_zfree(void *ptr) |
|
{ |
|
kfree_sensitive(ptr); |
|
} |
|
|
|
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; |
|
unsigned int reset_cnt; |
|
}; |
|
|
|
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); |
|
|
|
/* Return a permanent error in case we had too many resets in a row. */ |
|
if (rng->reset_cnt > (1<<10)) { |
|
ret = -EFAULT; |
|
goto out; |
|
} |
|
|
|
ret = jent_read_entropy(rng->entropy_collector, rdata, dlen); |
|
|
|
/* Reset RNG in case of health failures */ |
|
if (ret < -1) { |
|
pr_warn_ratelimited("Reset Jitter RNG due to health test failure: %s failure\n", |
|
(ret == -2) ? "Repetition Count Test" : |
|
"Adaptive Proportion Test"); |
|
|
|
rng->reset_cnt++; |
|
|
|
ret = -EAGAIN; |
|
} else { |
|
rng->reset_cnt = 0; |
|
|
|
/* Convert the Jitter RNG error into a usable error code */ |
|
if (ret == -1) |
|
ret = -EINVAL; |
|
} |
|
|
|
out: |
|
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 <[email protected]>"); |
|
MODULE_DESCRIPTION("Non-physical True Random Number Generator based on CPU Jitter"); |
|
MODULE_ALIAS_CRYPTO("jitterentropy_rng");
|
|
|