| /* |
| * 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); |
| } |
| |
| void jent_get_nstime(__u64 *out) |
| { |
| struct timespec ts; |
| __u64 tmp = 0; |
| |
| tmp = random_get_entropy(); |
| |
| /* |
| * If random_get_entropy does not return a value (which is possible on, |
| * for example, MIPS), invoke __getnstimeofday |
| * hoping that there are timers we can work with. |
| */ |
| if ((0 == tmp) && |
| (0 == __getnstimeofday(&ts))) { |
| tmp = ts.tv_sec; |
| tmp = tmp << 32; |
| tmp = tmp | ts.tv_nsec; |
| } |
| |
| *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"); |