2 * Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
3 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org>
4 * Copyright (c) 2004 Mark R V Murray
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer
12 * in this position and unchanged.
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.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #include <sys/param.h>
30 __FBSDID("$FreeBSD$");
32 #include <sys/kernel.h>
33 #include <sys/systm.h>
34 #include <sys/kthread.h>
36 #include <sys/random.h>
37 #include <sys/selinfo.h>
38 #include <sys/sysctl.h>
40 #include <sys/malloc.h>
41 #include <sys/queue.h>
42 #include <sys/libkern.h>
43 #include <sys/unistd.h>
45 #include <dev/random/randomdev.h>
46 #include <dev/random/randomdev_soft.h>
47 #include <dev/random/random_adaptors.h>
49 LIST_HEAD(adaptors_head, random_adaptors);
50 static struct adaptors_head adaptors = LIST_HEAD_INITIALIZER(adaptors);
51 static struct sx adaptors_lock; /* need a sleepable lock */
53 /* List for the dynamic sysctls */
54 static struct sysctl_ctx_list random_clist;
56 MALLOC_DEFINE(M_RANDOM_ADAPTORS, "random_adaptors", "Random adaptors buffers");
59 random_adaptor_register(const char *name, struct random_adaptor *rsp)
61 struct random_adaptors *rpp;
63 KASSERT(name != NULL && rsp != NULL, ("invalid input to %s", __func__));
65 rpp = malloc(sizeof(struct random_adaptors), M_RANDOM_ADAPTORS,
70 sx_xlock(&adaptors_lock);
71 LIST_INSERT_HEAD(&adaptors, rpp, entries);
72 sx_xunlock(&adaptors_lock);
77 struct random_adaptor *
78 random_adaptor_get(const char *name)
80 struct random_adaptors *rpp;
81 struct random_adaptor *rsp;
85 sx_slock(&adaptors_lock);
87 LIST_FOREACH(rpp, &adaptors, entries)
88 if (strcmp(rpp->name, name) == 0)
91 sx_sunlock(&adaptors_lock);
97 * In the past, the logic of the random_adaptor selection was inverted, such
98 * that hardware RNGs would be chosen unless disabled. This routine is here to
99 * preserve that functionality to avoid folks losing their hardware RNGs by
100 * upgrading to newer kernel.
103 random_adaptor_choose_legacy(struct random_adaptor **adaptor)
105 struct random_adaptor *tmp;
108 /* Then go looking for hardware */
110 TUNABLE_INT_FETCH("hw.nehemiah_rng_enable", &enable);
111 if (enable && (tmp = random_adaptor_get("nehemiah")))
115 TUNABLE_INT_FETCH("hw.ivy_rng_enable", &enable);
116 if (enable && (tmp = random_adaptor_get("rdrand")))
121 * Walk a list of registered random(4) adaptors and pick the last non-selected
124 * If none are selected, use yarrow if available.
127 random_adaptor_choose(struct random_adaptor **adaptor)
129 char rngs[128], *token, *cp;
130 struct random_adaptors *rpp;
132 KASSERT(adaptor != NULL, ("pre-conditions failed"));
136 random_adaptor_choose_legacy(adaptor);
138 if (*adaptor != NULL)
141 if (TUNABLE_STR_FETCH("rngs_want", rngs, sizeof(rngs))) {
144 while ((token = strsep(&cp, ",")) != NULL) {
145 if ((*adaptor = random_adaptor_get(token)) != NULL)
147 else if (bootverbose)
149 "%s random adaptor is not available, skipping\n",
154 if (*adaptor == NULL) {
156 * Either no RNGs are prefered via rngs_want tunable, or
157 * no prefered RNGs are registered.
158 * Fallback to Yarrow.
160 *adaptor = random_adaptor_get("yarrow");
162 if (*adaptor == NULL) {
164 * Yarrow doesn't seem to be available.
165 * Fallback to the first thing that's on the list of
168 sx_slock(&adaptors_lock);
170 rpp = LIST_FIRST(&adaptors);
174 sx_sunlock(&adaptors_lock);
177 if (bootverbose && *adaptor)
178 printf("Falling back to <%s> random adaptor",
184 random_adaptors_deinit(void *unused)
187 sx_destroy(&adaptors_lock);
188 sysctl_ctx_free(&random_clist);
192 random_sysctl_adaptors_handler(SYSCTL_HANDLER_ARGS)
194 struct random_adaptors *rpp;
199 sx_slock(&adaptors_lock);
201 if (LIST_EMPTY(&adaptors)) {
202 error = SYSCTL_OUT(req, "", 0);
205 LIST_FOREACH(rpp, &adaptors, entries) {
207 error = SYSCTL_OUT(req, ",", count++ ? 1 : 0);
212 error = SYSCTL_OUT(req, rpp->name, strlen(rpp->name));
219 sx_sunlock(&adaptors_lock);
225 random_sysctl_active_adaptor_handler(SYSCTL_HANDLER_ARGS)
227 struct random_adaptor *rsp;
228 struct random_adaptors *rpp;
233 rsp = random_get_active_adaptor();
236 sx_slock(&adaptors_lock);
238 LIST_FOREACH(rpp, &adaptors, entries) {
243 sx_sunlock(&adaptors_lock);
246 if (rsp == NULL || name == NULL) {
247 error = SYSCTL_OUT(req, "", 0);
249 error = SYSCTL_OUT(req, name, strlen(name));
256 random_adaptors_init(void *unused)
259 SYSCTL_PROC(_kern_random, OID_AUTO, adaptors,
260 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
261 NULL, 0, random_sysctl_adaptors_handler, "",
262 "Random Number Generator adaptors");
264 SYSCTL_PROC(_kern_random, OID_AUTO, active_adaptor,
265 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
266 NULL, 0, random_sysctl_active_adaptor_handler, "",
267 "Active Random Number Generator Adaptor");
269 sx_init(&adaptors_lock, "random_adaptors");
272 SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW, 0, "Random Number Generator");
274 SYSINIT(random_adaptors, SI_SUB_DRIVERS, SI_ORDER_FIRST, random_adaptors_init,
276 SYSUNINIT(random_adaptors, SI_SUB_DRIVERS, SI_ORDER_FIRST,
277 random_adaptors_deinit, NULL);