1 /*-
2 * Copyright (c) 2000-2013 Mark R V Murray
3 * Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer
11 * in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD: stable/10/sys/dev/random/randomdev.c 295480 2016-02-10 18:29:37Z jhb $");
31
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/bus.h>
35 #include <sys/conf.h>
36 #include <sys/fcntl.h>
37 #include <sys/filio.h>
38 #include <sys/kernel.h>
39 #include <sys/kthread.h>
40 #include <sys/lock.h>
41 #include <sys/malloc.h>
42 #include <sys/module.h>
43 #include <sys/mutex.h>
44 #include <sys/poll.h>
45 #include <sys/priv.h>
46 #include <sys/proc.h>
47 #include <sys/random.h>
48 #include <sys/selinfo.h>
49 #include <sys/uio.h>
50 #include <sys/unistd.h>
51
52 #include <machine/bus.h>
53 #include <machine/cpu.h>
54
55 #include <dev/random/randomdev.h>
56 #include <dev/random/randomdev_soft.h>
57 #include <dev/random/random_adaptors.h>
58 #include <dev/random/random_harvestq.h>
59 #include <dev/random/live_entropy_sources.h>
60
61 #define RANDOM_MINOR 0
62
63 static d_read_t random_read;
64 static d_write_t random_write;
65 static d_ioctl_t random_ioctl;
66 static d_poll_t random_poll;
67
68 static struct cdevsw random_cdevsw = {
69 .d_version = D_VERSION,
70 .d_read = random_read,
71 .d_write = random_write,
72 .d_ioctl = random_ioctl,
73 .d_poll = random_poll,
74 .d_name = "random",
75 };
76
77 /* For use with make_dev(9)/destroy_dev(9). */
78 static struct cdev *random_dev;
79
80 /* ARGSUSED */
81 static int
random_read(struct cdev * dev __unused,struct uio * uio,int flag)82 random_read(struct cdev *dev __unused, struct uio *uio, int flag)
83 {
84 int c, error = 0;
85 void *random_buf;
86
87 /* Blocking logic */
88 if (!random_adaptor->seeded)
89 error = (*random_adaptor->block)(flag);
90
91 /* The actual read */
92 if (!error) {
93
94 random_buf = (void *)malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK);
95
96 while (uio->uio_resid > 0 && !error) {
97 c = MIN(uio->uio_resid, PAGE_SIZE);
98 c = (*random_adaptor->read)(random_buf, c);
99 error = uiomove(random_buf, c, uio);
100 }
101 /* Finished reading; let the source know so it can do some
102 * optional housekeeping */
103 (*random_adaptor->read)(NULL, 0);
104
105 free(random_buf, M_ENTROPY);
106
107 }
108
109 return (error);
110 }
111
112 /* ARGSUSED */
113 static int
random_write(struct cdev * dev __unused,struct uio * uio,int flag __unused)114 random_write(struct cdev *dev __unused, struct uio *uio, int flag __unused)
115 {
116
117 /* We used to allow this to insert userland entropy.
118 * We don't any more because (1) this so-called entropy
119 * is usually lousy and (b) its vaguely possible to
120 * mess with entropy harvesting by overdoing a write.
121 * Now we just ignore input like /dev/null does.
122 */
123 uio->uio_resid = 0;
124
125 return (0);
126 }
127
128 /* ARGSUSED */
129 static int
random_ioctl(struct cdev * dev __unused,u_long cmd,caddr_t addr __unused,int flags __unused,struct thread * td __unused)130 random_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused,
131 int flags __unused, struct thread *td __unused)
132 {
133 int error = 0;
134
135 switch (cmd) {
136 /* Really handled in upper layer */
137 case FIOASYNC:
138 case FIONBIO:
139 break;
140 default:
141 error = ENOTTY;
142 }
143 return (error);
144 }
145
146 /* ARGSUSED */
147 static int
random_poll(struct cdev * dev __unused,int events,struct thread * td)148 random_poll(struct cdev *dev __unused, int events, struct thread *td)
149 {
150 int revents = 0;
151
152 if (events & (POLLIN | POLLRDNORM)) {
153 if (random_adaptor->seeded)
154 revents = events & (POLLIN | POLLRDNORM);
155 else
156 revents = (*random_adaptor->poll)(events, td);
157 }
158 return (revents);
159 }
160
161 static void
random_initialize(void * p,struct random_adaptor * s)162 random_initialize(void *p, struct random_adaptor *s)
163 {
164 static int random_inited = 0;
165
166 if (random_inited) {
167 printf("random: <%s> already initialized\n",
168 random_adaptor->ident);
169 return;
170 }
171
172 random_adaptor = s;
173
174 (s->init)();
175
176 printf("random: <%s> initialized\n", s->ident);
177
178 /* mark random(4) as initialized, to avoid being called again */
179 random_inited = 1;
180 }
181
182 static void
random_makedev(void * arg __unused)183 random_makedev(void *arg __unused)
184 {
185
186 if (random_adaptor == NULL)
187 return;
188
189 /* Use an appropriately evil mode for those who are concerned
190 * with daemons */
191 random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw,
192 RANDOM_MINOR, NULL, UID_ROOT, GID_WHEEL, 0666, "random");
193 make_dev_alias(random_dev, "urandom"); /* compatibility */
194 }
195 SYSINIT(random_makedev, SI_SUB_DRIVERS, SI_ORDER_ANY, random_makedev, NULL);
196
197 /* ARGSUSED */
198 static int
random_modevent(module_t mod __unused,int type,void * data __unused)199 random_modevent(module_t mod __unused, int type, void *data __unused)
200 {
201 static eventhandler_tag attach_tag = NULL;
202 int error = 0;
203
204 switch (type) {
205 case MOD_LOAD:
206 random_adaptor_choose(&random_adaptor);
207
208 if (random_adaptor == NULL) {
209 printf("random: No random adaptor attached, "
210 "postponing initialization\n");
211 attach_tag = EVENTHANDLER_REGISTER(random_adaptor_attach,
212 random_initialize, NULL, EVENTHANDLER_PRI_ANY);
213 } else
214 random_initialize(NULL, random_adaptor);
215
216 break;
217
218 case MOD_UNLOAD:
219 if (random_adaptor != NULL) {
220 (*random_adaptor->deinit)();
221 destroy_dev(random_dev);
222 }
223 /* Unregister the event handler */
224 if (attach_tag != NULL)
225 EVENTHANDLER_DEREGISTER(random_adaptor_attach,
226 attach_tag);
227
228 break;
229
230 case MOD_SHUTDOWN:
231 break;
232
233 default:
234 error = EOPNOTSUPP;
235 break;
236
237 }
238 return (error);
239 }
240
241 static moduledata_t random_mod = {
242 "random",
243 random_modevent,
244 NULL
245 };
246
247 DECLARE_MODULE(random, random_mod, SI_SUB_RANDOM, SI_ORDER_MIDDLE);
248 MODULE_VERSION(random, 1);
249