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dfc9fa91 SM |
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 | { | |
0c5f0aa5 | 82 | panic("%s", s); |
dfc9fa91 SM |
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"); |