randomdev.c revision 253779 
1/*-
2 * Copyright (c) 2000-2004 Mark R V Murray
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer
10 *    in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD: head/sys/dev/random/randomdev.c 253779 2013-07-29 20:26:27Z obrien $");
30
31#include <sys/param.h>
32#include <sys/systm.h>
33#include <sys/bus.h>
34#include <sys/conf.h>
35#include <sys/fcntl.h>
36#include <sys/filio.h>
37#include <sys/kernel.h>
38#include <sys/kthread.h>
39#include <sys/lock.h>
40#include <sys/malloc.h>
41#include <sys/module.h>
42#include <sys/mutex.h>
43#include <sys/poll.h>
44#include <sys/priv.h>
45#include <sys/proc.h>
46#include <sys/selinfo.h>
47#include <sys/uio.h>
48#include <sys/unistd.h>
49
50#include <machine/bus.h>
51#include <machine/cpu.h>
52
53#include <dev/random/randomdev.h>
54
55#define RANDOM_MINOR	0
56
57static d_close_t random_close;
58static d_read_t random_read;
59static d_write_t random_write;
60static d_ioctl_t random_ioctl;
61static d_poll_t random_poll;
62
63static struct cdevsw random_cdevsw = {
64	.d_version = D_VERSION,
65	.d_close = random_close,
66	.d_read = random_read,
67	.d_write = random_write,
68	.d_ioctl = random_ioctl,
69	.d_poll = random_poll,
70	.d_name = "random",
71};
72
73static struct random_adaptor *random_adaptor;
74static eventhandler_tag attach_tag;
75static int random_inited;
76
77
78/* For use with make_dev(9)/destroy_dev(9). */
79static struct cdev *random_dev;
80
81/* Used to fake out unused random calls in random_adaptor */
82void
83random_null_func(void)
84{
85}
86
87/* ARGSUSED */
88static int
89random_close(struct cdev *dev __unused, int flags, int fmt __unused,
90    struct thread *td)
91{
92	if ((flags & FWRITE) && (priv_check(td, PRIV_RANDOM_RESEED) == 0)
93	    && (securelevel_gt(td->td_ucred, 0) == 0)) {
94		(*random_adaptor->reseed)();
95		random_adaptor->seeded = 1;
96		arc4rand(NULL, 0, 1);	/* Reseed arc4random as well. */
97	}
98
99	return (0);
100}
101
102/* ARGSUSED */
103static int
104random_read(struct cdev *dev __unused, struct uio *uio, int flag)
105{
106	int c, error = 0;
107	void *random_buf;
108
109	/* Blocking logic */
110	if (!random_adaptor->seeded)
111		error = (*random_adaptor->block)(flag);
112
113	/* The actual read */
114	if (!error) {
115
116		random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
117
118		while (uio->uio_resid > 0 && !error) {
119			c = MIN(uio->uio_resid, PAGE_SIZE);
120			c = (*random_adaptor->read)(random_buf, c);
121			error = uiomove(random_buf, c, uio);
122		}
123
124		free(random_buf, M_TEMP);
125
126	}
127
128	return (error);
129}
130
131/* ARGSUSED */
132static int
133random_write(struct cdev *dev __unused, struct uio *uio, int flag __unused)
134{
135	int c, error = 0;
136	void *random_buf;
137
138	random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
139
140	while (uio->uio_resid > 0) {
141		c = MIN((int)uio->uio_resid, PAGE_SIZE);
142		error = uiomove(random_buf, c, uio);
143		if (error)
144			break;
145		(*random_adaptor->write)(random_buf, c);
146	}
147
148	free(random_buf, M_TEMP);
149
150	return (error);
151}
152
153/* ARGSUSED */
154static int
155random_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused,
156    int flags __unused, struct thread *td __unused)
157{
158	int error = 0;
159
160	switch (cmd) {
161		/* Really handled in upper layer */
162	case FIOASYNC:
163	case FIONBIO:
164		break;
165	default:
166		error = ENOTTY;
167	}
168	return (error);
169}
170
171/* ARGSUSED */
172static int
173random_poll(struct cdev *dev __unused, int events, struct thread *td)
174{
175	int revents = 0;
176
177	if (events & (POLLIN | POLLRDNORM)) {
178		if (random_adaptor->seeded)
179			revents = events & (POLLIN | POLLRDNORM);
180		else
181			revents = (*random_adaptor->poll) (events,td);
182	}
183	return (revents);
184}
185
186static void
187random_initialize(void *p, struct random_adaptor *s)
188{
189	if (random_inited) {
190		printf("random: <%s> already initialized\n",
191		    random_adaptor->ident);
192		return;
193	}
194
195	random_adaptor = s;
196
197	(s->init)();
198
199	printf("random: <%s> initialized\n", s->ident);
200
201	random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw,
202	    RANDOM_MINOR, NULL, UID_ROOT, GID_WHEEL, 0666, "random");
203	make_dev_alias(random_dev, "urandom");	/* XXX Deprecated */
204
205	/* mark random(4) as initialized, to avoid being called again */
206	random_inited = 1;
207}
208
209/* ARGSUSED */
210static int
211random_modevent(module_t mod __unused, int type, void *data __unused)
212{
213	int error = 0;
214
215	switch (type) {
216	case MOD_LOAD:
217		random_ident_hardware(&random_adaptor);
218
219		if (random_adaptor == NULL) {
220			printf(
221       "random: No random adaptor attached, postponing initialization\n");
222			attach_tag = EVENTHANDLER_REGISTER(random_adaptor_attach,
223			    random_initialize, NULL, EVENTHANDLER_PRI_ANY);
224		} else {
225			random_initialize(NULL, random_adaptor);
226		}
227
228		break;
229
230	case MOD_UNLOAD:
231		if (random_adaptor != NULL) {
232			(*random_adaptor->deinit)();
233			destroy_dev(random_dev);
234		}
235		/* Unregister the event handler */
236		if (attach_tag != NULL) {
237			EVENTHANDLER_DEREGISTER(random_adaptor_attach,
238			    attach_tag);
239		}
240
241		break;
242
243	case MOD_SHUTDOWN:
244		break;
245
246	default:
247		error = EOPNOTSUPP;
248		break;
249
250	}
251	return (error);
252}
253
254DEV_MODULE(random, random_modevent, NULL);
255MODULE_VERSION(random, 1);
256