randomdev.c revision 255362 
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 255362 2013-09-07 14:15:13Z 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 struct random_adaptor *random_adaptor;
76static eventhandler_tag attach_tag;
77static int random_inited;
78
79
80/* For use with make_dev(9)/destroy_dev(9). */
81static struct cdev *random_dev;
82
83/* Used to fake out unused random calls in random_adaptor */
84void
85random_null_func(void)
86{
87}
88
89struct random_adaptor *
90random_get_active_adaptor(void)
91{
92
93	return (random_adaptor);
94}
95
96/* ARGSUSED */
97static int
98random_close(struct cdev *dev __unused, int flags, int fmt __unused,
99    struct thread *td)
100{
101	if ((flags & FWRITE) && (priv_check(td, PRIV_RANDOM_RESEED) == 0)
102	    && (securelevel_gt(td->td_ucred, 0) == 0)) {
103		(*random_adaptor->reseed)();
104		random_adaptor->seeded = 1;
105		arc4rand(NULL, 0, 1);	/* Reseed arc4random as well. */
106	}
107
108	return (0);
109}
110
111/* ARGSUSED */
112static int
113random_read(struct cdev *dev __unused, struct uio *uio, int flag)
114{
115	int c, error = 0;
116	void *random_buf;
117
118	/* Blocking logic */
119	if (!random_adaptor->seeded)
120		error = (*random_adaptor->block)(flag);
121
122	/* The actual read */
123	if (!error) {
124
125		random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
126
127		while (uio->uio_resid > 0 && !error) {
128			c = MIN(uio->uio_resid, PAGE_SIZE);
129			c = (*random_adaptor->read)(random_buf, c);
130			error = uiomove(random_buf, c, uio);
131		}
132
133		free(random_buf, M_TEMP);
134
135	}
136
137	return (error);
138}
139
140/* ARGSUSED */
141static int
142random_write(struct cdev *dev __unused, struct uio *uio, int flag __unused)
143{
144	int c, error = 0;
145	void *random_buf;
146
147	random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
148
149	while (uio->uio_resid > 0) {
150		c = MIN((int)uio->uio_resid, PAGE_SIZE);
151		error = uiomove(random_buf, c, uio);
152		if (error)
153			break;
154		(*random_adaptor->write)(random_buf, c);
155	}
156
157	free(random_buf, M_TEMP);
158
159	return (error);
160}
161
162/* ARGSUSED */
163static int
164random_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr __unused,
165    int flags __unused, struct thread *td __unused)
166{
167	int error = 0;
168
169	switch (cmd) {
170		/* Really handled in upper layer */
171	case FIOASYNC:
172	case FIONBIO:
173		break;
174	default:
175		error = ENOTTY;
176	}
177	return (error);
178}
179
180/* ARGSUSED */
181static int
182random_poll(struct cdev *dev __unused, int events, struct thread *td)
183{
184	int revents = 0;
185
186	if (events & (POLLIN | POLLRDNORM)) {
187		if (random_adaptor->seeded)
188			revents = events & (POLLIN | POLLRDNORM);
189		else
190			revents = (*random_adaptor->poll) (events,td);
191	}
192	return (revents);
193}
194
195static void
196random_initialize(void *p, struct random_adaptor *s)
197{
198	if (random_inited) {
199		printf("random: <%s> already initialized\n",
200		    random_adaptor->ident);
201		return;
202	}
203
204	random_adaptor = s;
205
206	(s->init)();
207
208	printf("random: <%s> initialized\n", s->ident);
209
210	random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw,
211	    RANDOM_MINOR, NULL, UID_ROOT, GID_WHEEL, 0666, "random");
212	make_dev_alias(random_dev, "urandom");	/* XXX Deprecated */
213
214	/* mark random(4) as initialized, to avoid being called again */
215	random_inited = 1;
216}
217
218/* ARGSUSED */
219static int
220random_modevent(module_t mod __unused, int type, void *data __unused)
221{
222	int error = 0;
223
224	switch (type) {
225	case MOD_LOAD:
226		random_adaptor_choose(&random_adaptor);
227
228		if (random_adaptor == NULL) {
229			printf(
230       "random: No random adaptor attached, postponing initialization\n");
231			attach_tag = EVENTHANDLER_REGISTER(random_adaptor_attach,
232			    random_initialize, NULL, EVENTHANDLER_PRI_ANY);
233		} else {
234			random_initialize(NULL, random_adaptor);
235		}
236
237		break;
238
239	case MOD_UNLOAD:
240		if (random_adaptor != NULL) {
241			(*random_adaptor->deinit)();
242			destroy_dev(random_dev);
243		}
244		/* Unregister the event handler */
245		if (attach_tag != NULL) {
246			EVENTHANDLER_DEREGISTER(random_adaptor_attach,
247			    attach_tag);
248		}
249
250		break;
251
252	case MOD_SHUTDOWN:
253		break;
254
255	default:
256		error = EOPNOTSUPP;
257		break;
258
259	}
260	return (error);
261}
262
263DEV_MODULE(random, random_modevent, NULL);
264MODULE_VERSION(random, 1);
265