randomdev.c revision 255379 
1/*-
2 * Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
3 * Copyright (c) 2000-2004 Mark R V Murray
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: head/sys/dev/random/randomdev.c 255379 2013-09-07 22:07:36Z 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/selinfo.h>
48#include <sys/uio.h>
49#include <sys/unistd.h>
50
51#include <machine/bus.h>
52#include <machine/cpu.h>
53
54#include <dev/random/random_adaptors.h>
55#include <dev/random/randomdev.h>
56
57#define RANDOM_MINOR	0
58
59static d_close_t random_close;
60static d_read_t random_read;
61static d_write_t random_write;
62static d_ioctl_t random_ioctl;
63static d_poll_t random_poll;
64
65static struct cdevsw random_cdevsw = {
66	.d_version = D_VERSION,
67	.d_close = random_close,
68	.d_read = random_read,
69	.d_write = random_write,
70	.d_ioctl = random_ioctl,
71	.d_poll = random_poll,
72	.d_name = "random",
73};
74
75static eventhandler_tag attach_tag;
76static int random_inited;
77
78/* For use with make_dev(9)/destroy_dev(9). */
79static struct cdev *random_dev;
80
81/* ARGSUSED */
82static int
83random_close(struct cdev *dev __unused, int flags, int fmt __unused,
84    struct thread *td)
85{
86	if ((flags & FWRITE) && (priv_check(td, PRIV_RANDOM_RESEED) == 0)
87	    && (securelevel_gt(td->td_ucred, 0) == 0)) {
88		(*random_adaptor->reseed)();
89		random_adaptor->seeded = 1;
90		arc4rand(NULL, 0, 1);	/* Reseed arc4random as well. */
91	}
92
93	return (0);
94}
95
96/* ARGSUSED */
97static int
98random_read(struct cdev *dev __unused, struct uio *uio, int flag)
99{
100	int c, error = 0;
101	void *random_buf;
102
103	/* Blocking logic */
104	if (!random_adaptor->seeded)
105		error = (*random_adaptor->block)(flag);
106
107	/* The actual read */
108	if (!error) {
109
110		random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
111
112		while (uio->uio_resid > 0 && !error) {
113			c = MIN(uio->uio_resid, PAGE_SIZE);
114			c = (*random_adaptor->read)(random_buf, c);
115			error = uiomove(random_buf, c, uio);
116		}
117
118		free(random_buf, M_TEMP);
119
120	}
121
122	return (error);
123}
124
125/* ARGSUSED */
126static int
127random_write(struct cdev *dev __unused, struct uio *uio, int flag __unused)
128{
129	int c, error = 0;
130	void *random_buf;
131
132	random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
133
134	while (uio->uio_resid > 0) {
135		c = MIN((int)uio->uio_resid, PAGE_SIZE);
136		error = uiomove(random_buf, c, uio);
137		if (error)
138			break;
139		(*random_adaptor->write)(random_buf, c);
140	}
141
142	free(random_buf, M_TEMP);
143
144	return (error);
145}
146
147/* ARGSUSED */
148static int
149random_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused,
150    int flags __unused, struct thread *td __unused)
151{
152	int error = 0;
153
154	switch (cmd) {
155		/* Really handled in upper layer */
156	case FIOASYNC:
157	case FIONBIO:
158		break;
159	default:
160		error = ENOTTY;
161	}
162	return (error);
163}
164
165/* ARGSUSED */
166static int
167random_poll(struct cdev *dev __unused, int events, struct thread *td)
168{
169	int revents = 0;
170
171	if (events & (POLLIN | POLLRDNORM)) {
172		if (random_adaptor->seeded)
173			revents = events & (POLLIN | POLLRDNORM);
174		else
175			revents = (*random_adaptor->poll) (events,td);
176	}
177	return (revents);
178}
179
180static void
181random_initialize(void *p, struct random_adaptor *s)
182{
183	if (random_inited) {
184		printf("random: <%s> already initialized\n",
185		    random_adaptor->ident);
186		return;
187	}
188
189	random_adaptor = s;
190
191	(s->init)();
192
193	printf("random: <%s> initialized\n", s->ident);
194
195	random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw,
196	    RANDOM_MINOR, NULL, UID_ROOT, GID_WHEEL, 0666, "random");
197	make_dev_alias(random_dev, "urandom");	/* XXX Deprecated */
198
199	/* mark random(4) as initialized, to avoid being called again */
200	random_inited = 1;
201}
202
203/* ARGSUSED */
204static int
205random_modevent(module_t mod __unused, int type, void *data __unused)
206{
207	int error = 0;
208
209	switch (type) {
210	case MOD_LOAD:
211		random_adaptor_choose(&random_adaptor);
212
213		if (random_adaptor == NULL) {
214			printf(
215       "random: No random adaptor attached, postponing initialization\n");
216			attach_tag = EVENTHANDLER_REGISTER(random_adaptor_attach,
217			    random_initialize, NULL, EVENTHANDLER_PRI_ANY);
218		} else {
219			random_initialize(NULL, random_adaptor);
220		}
221
222		break;
223
224	case MOD_UNLOAD:
225		if (random_adaptor != NULL) {
226			(*random_adaptor->deinit)();
227			destroy_dev(random_dev);
228		}
229		/* Unregister the event handler */
230		if (attach_tag != NULL) {
231			EVENTHANDLER_DEREGISTER(random_adaptor_attach,
232			    attach_tag);
233		}
234
235		break;
236
237	case MOD_SHUTDOWN:
238		break;
239
240	default:
241		error = EOPNOTSUPP;
242		break;
243
244	}
245	return (error);
246}
247
248DEV_MODULE(random, random_modevent, NULL);
249MODULE_VERSION(random, 1);
250