Commit | Line | Data |
---|---|---|
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 | ||
3fde2fe9 | 40 | #include <linux/fips.h> |
0c3dc787 | 41 | #include <linux/kernel.h> |
dfc9fa91 SM |
42 | #include <linux/module.h> |
43 | #include <linux/slab.h> | |
dfc9fa91 | 44 | #include <linux/time.h> |
dfc9fa91 SM |
45 | #include <crypto/internal/rng.h> |
46 | ||
965d7286 | 47 | #include "jitterentropy.h" |
dfc9fa91 SM |
48 | |
49 | /*************************************************************************** | |
50 | * Helper function | |
51 | ***************************************************************************/ | |
52 | ||
dfc9fa91 SM |
53 | void *jent_zalloc(unsigned int len) |
54 | { | |
55 | return kzalloc(len, GFP_KERNEL); | |
56 | } | |
57 | ||
58 | void jent_zfree(void *ptr) | |
59 | { | |
453431a5 | 60 | kfree_sensitive(ptr); |
dfc9fa91 SM |
61 | } |
62 | ||
dfc9fa91 SM |
63 | void jent_memcpy(void *dest, const void *src, unsigned int n) |
64 | { | |
65 | memcpy(dest, src, n); | |
66 | } | |
67 | ||
b578456c SM |
68 | /* |
69 | * Obtain a high-resolution time stamp value. The time stamp is used to measure | |
70 | * the execution time of a given code path and its variations. Hence, the time | |
71 | * stamp must have a sufficiently high resolution. | |
72 | * | |
73 | * Note, if the function returns zero because a given architecture does not | |
74 | * implement a high-resolution time stamp, the RNG code's runtime test | |
75 | * will detect it and will not produce output. | |
76 | */ | |
dfc9fa91 SM |
77 | void jent_get_nstime(__u64 *out) |
78 | { | |
dfc9fa91 SM |
79 | __u64 tmp = 0; |
80 | ||
81 | tmp = random_get_entropy(); | |
82 | ||
83 | /* | |
b578456c SM |
84 | * If random_get_entropy does not return a value, i.e. it is not |
85 | * implemented for a given architecture, use a clock source. | |
dfc9fa91 | 86 | * hoping that there are timers we can work with. |
dfc9fa91 | 87 | */ |
b578456c SM |
88 | if (tmp == 0) |
89 | tmp = ktime_get_ns(); | |
dfc9fa91 SM |
90 | |
91 | *out = tmp; | |
92 | } | |
93 | ||
94 | /*************************************************************************** | |
95 | * Kernel crypto API interface | |
96 | ***************************************************************************/ | |
97 | ||
98 | struct jitterentropy { | |
99 | spinlock_t jent_lock; | |
100 | struct rand_data *entropy_collector; | |
101 | }; | |
102 | ||
103 | static int jent_kcapi_init(struct crypto_tfm *tfm) | |
104 | { | |
105 | struct jitterentropy *rng = crypto_tfm_ctx(tfm); | |
106 | int ret = 0; | |
107 | ||
108 | rng->entropy_collector = jent_entropy_collector_alloc(1, 0); | |
109 | if (!rng->entropy_collector) | |
110 | ret = -ENOMEM; | |
111 | ||
112 | spin_lock_init(&rng->jent_lock); | |
113 | return ret; | |
114 | } | |
115 | ||
116 | static void jent_kcapi_cleanup(struct crypto_tfm *tfm) | |
117 | { | |
118 | struct jitterentropy *rng = crypto_tfm_ctx(tfm); | |
119 | ||
120 | spin_lock(&rng->jent_lock); | |
121 | if (rng->entropy_collector) | |
122 | jent_entropy_collector_free(rng->entropy_collector); | |
123 | rng->entropy_collector = NULL; | |
124 | spin_unlock(&rng->jent_lock); | |
125 | } | |
126 | ||
127 | static int jent_kcapi_random(struct crypto_rng *tfm, | |
128 | const u8 *src, unsigned int slen, | |
129 | u8 *rdata, unsigned int dlen) | |
130 | { | |
131 | struct jitterentropy *rng = crypto_rng_ctx(tfm); | |
132 | int ret = 0; | |
133 | ||
134 | spin_lock(&rng->jent_lock); | |
764428fe | 135 | |
dfc9fa91 | 136 | ret = jent_read_entropy(rng->entropy_collector, rdata, dlen); |
764428fe | 137 | |
3fde2fe9 SM |
138 | if (ret == -3) { |
139 | /* Handle permanent health test error */ | |
140 | /* | |
141 | * If the kernel was booted with fips=1, it implies that | |
142 | * the entire kernel acts as a FIPS 140 module. In this case | |
143 | * an SP800-90B permanent health test error is treated as | |
144 | * a FIPS module error. | |
145 | */ | |
146 | if (fips_enabled) | |
147 | panic("Jitter RNG permanent health test failure\n"); | |
148 | ||
149 | pr_err("Jitter RNG permanent health test failure\n"); | |
150 | ret = -EFAULT; | |
151 | } else if (ret == -2) { | |
152 | /* Handle intermittent health test error */ | |
153 | pr_warn_ratelimited("Reset Jitter RNG due to intermittent health test failure\n"); | |
764428fe | 154 | ret = -EAGAIN; |
3fde2fe9 SM |
155 | } else if (ret == -1) { |
156 | /* Handle other errors */ | |
157 | ret = -EINVAL; | |
764428fe SM |
158 | } |
159 | ||
dfc9fa91 SM |
160 | spin_unlock(&rng->jent_lock); |
161 | ||
162 | return ret; | |
163 | } | |
164 | ||
165 | static int jent_kcapi_reset(struct crypto_rng *tfm, | |
166 | const u8 *seed, unsigned int slen) | |
167 | { | |
168 | return 0; | |
169 | } | |
170 | ||
171 | static struct rng_alg jent_alg = { | |
172 | .generate = jent_kcapi_random, | |
173 | .seed = jent_kcapi_reset, | |
174 | .seedsize = 0, | |
175 | .base = { | |
176 | .cra_name = "jitterentropy_rng", | |
177 | .cra_driver_name = "jitterentropy_rng", | |
178 | .cra_priority = 100, | |
179 | .cra_ctxsize = sizeof(struct jitterentropy), | |
180 | .cra_module = THIS_MODULE, | |
181 | .cra_init = jent_kcapi_init, | |
182 | .cra_exit = jent_kcapi_cleanup, | |
183 | ||
184 | } | |
185 | }; | |
186 | ||
187 | static int __init jent_mod_init(void) | |
188 | { | |
189 | int ret = 0; | |
190 | ||
191 | ret = jent_entropy_init(); | |
192 | if (ret) { | |
3fde2fe9 SM |
193 | /* Handle permanent health test error */ |
194 | if (fips_enabled) | |
195 | panic("jitterentropy: Initialization failed with host not compliant with requirements: %d\n", ret); | |
196 | ||
dfc9fa91 SM |
197 | pr_info("jitterentropy: Initialization failed with host not compliant with requirements: %d\n", ret); |
198 | return -EFAULT; | |
199 | } | |
200 | return crypto_register_rng(&jent_alg); | |
201 | } | |
202 | ||
203 | static void __exit jent_mod_exit(void) | |
204 | { | |
205 | crypto_unregister_rng(&jent_alg); | |
206 | } | |
207 | ||
9c5b34c2 | 208 | module_init(jent_mod_init); |
dfc9fa91 SM |
209 | module_exit(jent_mod_exit); |
210 | ||
211 | MODULE_LICENSE("Dual BSD/GPL"); | |
212 | MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>"); | |
213 | MODULE_DESCRIPTION("Non-physical True Random Number Generator based on CPU Jitter"); | |
214 | MODULE_ALIAS_CRYPTO("jitterentropy_rng"); |