Stephan Mueller | dfc9fa9 | 2015-06-23 16:18:54 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Non-physical true random number generator based on timing jitter -- |
| 3 | * Linux Kernel Crypto API specific code |
| 4 | * |
| 5 | * Copyright Stephan Mueller <smueller@chronox.de>, 2015 |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * 1. Redistributions of source code must retain the above copyright |
| 11 | * notice, and the entire permission notice in its entirety, |
| 12 | * including the disclaimer of warranties. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer in the |
| 15 | * documentation and/or other materials provided with the distribution. |
| 16 | * 3. The name of the author may not be used to endorse or promote |
| 17 | * products derived from this software without specific prior |
| 18 | * written permission. |
| 19 | * |
| 20 | * ALTERNATIVELY, this product may be distributed under the terms of |
| 21 | * the GNU General Public License, in which case the provisions of the GPL2 are |
| 22 | * required INSTEAD OF the above restrictions. (This clause is |
| 23 | * necessary due to a potential bad interaction between the GPL and |
| 24 | * the restrictions contained in a BSD-style copyright.) |
| 25 | * |
| 26 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 27 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 28 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF |
| 29 | * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE |
| 30 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 31 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| 32 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
| 33 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| 34 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 35 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE |
| 36 | * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH |
| 37 | * DAMAGE. |
| 38 | */ |
| 39 | |
| 40 | #include <linux/module.h> |
| 41 | #include <linux/slab.h> |
| 42 | #include <linux/module.h> |
| 43 | #include <linux/fips.h> |
| 44 | #include <linux/time.h> |
| 45 | #include <linux/crypto.h> |
| 46 | #include <crypto/internal/rng.h> |
| 47 | |
| 48 | struct rand_data; |
| 49 | int jent_read_entropy(struct rand_data *ec, unsigned char *data, |
| 50 | unsigned int len); |
| 51 | int jent_entropy_init(void); |
| 52 | struct rand_data *jent_entropy_collector_alloc(unsigned int osr, |
| 53 | unsigned int flags); |
| 54 | void jent_entropy_collector_free(struct rand_data *entropy_collector); |
| 55 | |
| 56 | /*************************************************************************** |
| 57 | * Helper function |
| 58 | ***************************************************************************/ |
| 59 | |
| 60 | __u64 jent_rol64(__u64 word, unsigned int shift) |
| 61 | { |
| 62 | return rol64(word, shift); |
| 63 | } |
| 64 | |
| 65 | void *jent_zalloc(unsigned int len) |
| 66 | { |
| 67 | return kzalloc(len, GFP_KERNEL); |
| 68 | } |
| 69 | |
| 70 | void jent_zfree(void *ptr) |
| 71 | { |
| 72 | kzfree(ptr); |
| 73 | } |
| 74 | |
| 75 | int jent_fips_enabled(void) |
| 76 | { |
| 77 | return fips_enabled; |
| 78 | } |
| 79 | |
| 80 | void jent_panic(char *s) |
| 81 | { |
| 82 | panic(s); |
| 83 | } |
| 84 | |
| 85 | void jent_memcpy(void *dest, const void *src, unsigned int n) |
| 86 | { |
| 87 | memcpy(dest, src, n); |
| 88 | } |
| 89 | |
| 90 | void jent_get_nstime(__u64 *out) |
| 91 | { |
| 92 | struct timespec ts; |
| 93 | __u64 tmp = 0; |
| 94 | |
| 95 | tmp = random_get_entropy(); |
| 96 | |
| 97 | /* |
| 98 | * If random_get_entropy does not return a value (which is possible on, |
| 99 | * for example, MIPS), invoke __getnstimeofday |
| 100 | * hoping that there are timers we can work with. |
| 101 | * |
| 102 | * The list of available timers can be obtained from |
| 103 | * /sys/devices/system/clocksource/clocksource0/available_clocksource |
| 104 | * and are registered with clocksource_register() |
| 105 | */ |
| 106 | if ((0 == tmp) && |
| 107 | (0 == __getnstimeofday(&ts))) { |
| 108 | tmp = ts.tv_sec; |
| 109 | tmp = tmp << 32; |
| 110 | tmp = tmp | ts.tv_nsec; |
| 111 | } |
| 112 | |
| 113 | *out = tmp; |
| 114 | } |
| 115 | |
| 116 | /*************************************************************************** |
| 117 | * Kernel crypto API interface |
| 118 | ***************************************************************************/ |
| 119 | |
| 120 | struct jitterentropy { |
| 121 | spinlock_t jent_lock; |
| 122 | struct rand_data *entropy_collector; |
| 123 | }; |
| 124 | |
| 125 | static int jent_kcapi_init(struct crypto_tfm *tfm) |
| 126 | { |
| 127 | struct jitterentropy *rng = crypto_tfm_ctx(tfm); |
| 128 | int ret = 0; |
| 129 | |
| 130 | rng->entropy_collector = jent_entropy_collector_alloc(1, 0); |
| 131 | if (!rng->entropy_collector) |
| 132 | ret = -ENOMEM; |
| 133 | |
| 134 | spin_lock_init(&rng->jent_lock); |
| 135 | return ret; |
| 136 | } |
| 137 | |
| 138 | static void jent_kcapi_cleanup(struct crypto_tfm *tfm) |
| 139 | { |
| 140 | struct jitterentropy *rng = crypto_tfm_ctx(tfm); |
| 141 | |
| 142 | spin_lock(&rng->jent_lock); |
| 143 | if (rng->entropy_collector) |
| 144 | jent_entropy_collector_free(rng->entropy_collector); |
| 145 | rng->entropy_collector = NULL; |
| 146 | spin_unlock(&rng->jent_lock); |
| 147 | } |
| 148 | |
| 149 | static int jent_kcapi_random(struct crypto_rng *tfm, |
| 150 | const u8 *src, unsigned int slen, |
| 151 | u8 *rdata, unsigned int dlen) |
| 152 | { |
| 153 | struct jitterentropy *rng = crypto_rng_ctx(tfm); |
| 154 | int ret = 0; |
| 155 | |
| 156 | spin_lock(&rng->jent_lock); |
| 157 | ret = jent_read_entropy(rng->entropy_collector, rdata, dlen); |
| 158 | spin_unlock(&rng->jent_lock); |
| 159 | |
| 160 | return ret; |
| 161 | } |
| 162 | |
| 163 | static int jent_kcapi_reset(struct crypto_rng *tfm, |
| 164 | const u8 *seed, unsigned int slen) |
| 165 | { |
| 166 | return 0; |
| 167 | } |
| 168 | |
| 169 | static struct rng_alg jent_alg = { |
| 170 | .generate = jent_kcapi_random, |
| 171 | .seed = jent_kcapi_reset, |
| 172 | .seedsize = 0, |
| 173 | .base = { |
| 174 | .cra_name = "jitterentropy_rng", |
| 175 | .cra_driver_name = "jitterentropy_rng", |
| 176 | .cra_priority = 100, |
| 177 | .cra_ctxsize = sizeof(struct jitterentropy), |
| 178 | .cra_module = THIS_MODULE, |
| 179 | .cra_init = jent_kcapi_init, |
| 180 | .cra_exit = jent_kcapi_cleanup, |
| 181 | |
| 182 | } |
| 183 | }; |
| 184 | |
| 185 | static int __init jent_mod_init(void) |
| 186 | { |
| 187 | int ret = 0; |
| 188 | |
| 189 | ret = jent_entropy_init(); |
| 190 | if (ret) { |
| 191 | pr_info("jitterentropy: Initialization failed with host not compliant with requirements: %d\n", ret); |
| 192 | return -EFAULT; |
| 193 | } |
| 194 | return crypto_register_rng(&jent_alg); |
| 195 | } |
| 196 | |
| 197 | static void __exit jent_mod_exit(void) |
| 198 | { |
| 199 | crypto_unregister_rng(&jent_alg); |
| 200 | } |
| 201 | |
| 202 | module_init(jent_mod_init); |
| 203 | module_exit(jent_mod_exit); |
| 204 | |
| 205 | MODULE_LICENSE("Dual BSD/GPL"); |
| 206 | MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>"); |
| 207 | MODULE_DESCRIPTION("Non-physical True Random Number Generator based on CPU Jitter"); |
| 208 | MODULE_ALIAS_CRYPTO("jitterentropy_rng"); |