randomdev.c revision 256381 
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 256381 2013-10-12 15:31:36Z markm $");
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
63static d_read_t random_read;
64static d_write_t random_write;
65static d_ioctl_t random_ioctl;
66static d_poll_t random_poll;
67
68static 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). */
78static struct cdev *random_dev;
79
80/* ARGSUSED */
81static int
82random_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 */
113static int
114random_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 */
129static int
130random_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 */
147static int
148random_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
161static void
162random_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	/* Use an appropriately evil mode for those who are concerned
179	 * with daemons */
180	random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw,
181	    RANDOM_MINOR, NULL, UID_ROOT, GID_WHEEL, 0666, "random");
182	make_dev_alias(random_dev, "urandom"); /* compatibility */
183
184	/* mark random(4) as initialized, to avoid being called again */
185	random_inited = 1;
186}
187
188/* ARGSUSED */
189static int
190random_modevent(module_t mod __unused, int type, void *data __unused)
191{
192	static eventhandler_tag attach_tag = NULL;
193	int error = 0;
194
195	switch (type) {
196	case MOD_LOAD:
197		random_adaptor_choose(&random_adaptor);
198
199		if (random_adaptor == NULL) {
200			printf("random: No random adaptor attached, "
201			    "postponing initialization\n");
202			attach_tag = EVENTHANDLER_REGISTER(random_adaptor_attach,
203			    random_initialize, NULL, EVENTHANDLER_PRI_ANY);
204		} else
205			random_initialize(NULL, random_adaptor);
206
207		break;
208
209	case MOD_UNLOAD:
210		if (random_adaptor != NULL) {
211			(*random_adaptor->deinit)();
212			destroy_dev(random_dev);
213		}
214		/* Unregister the event handler */
215		if (attach_tag != NULL)
216			EVENTHANDLER_DEREGISTER(random_adaptor_attach,
217			    attach_tag);
218
219		break;
220
221	case MOD_SHUTDOWN:
222		break;
223
224	default:
225		error = EOPNOTSUPP;
226		break;
227
228	}
229	return (error);
230}
231
232DEV_MODULE(random, random_modevent, NULL);
233MODULE_VERSION(random, 1);
234