randomdev.c revision 128151 
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 128151 2004-04-12 09:13:24Z markm $");
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/mutex.h>
42#include <sys/poll.h>
43#include <sys/proc.h>
44#include <sys/selinfo.h>
45#include <sys/uio.h>
46#include <sys/unistd.h>
47#include <sys/vnode.h>
48
49#include <machine/bus.h>
50#include <machine/cpu.h>
51
52#include <dev/random/randomdev.h>
53
54#define RANDOM_MINOR	0
55
56static d_close_t random_close;
57static d_read_t random_read;
58static d_write_t random_write;
59static d_ioctl_t random_ioctl;
60static d_poll_t random_poll;
61
62static struct cdevsw random_cdevsw = {
63	.d_version = D_VERSION,
64	.d_close = random_close,
65	.d_read = random_read,
66	.d_write = random_write,
67	.d_ioctl = random_ioctl,
68	.d_poll = random_poll,
69	.d_name = "random",
70};
71
72static void *random_buf;
73
74struct random_systat random_systat;
75
76/* For use with make_dev(9)/destroy_dev(9). */
77static dev_t random_dev;
78
79/* Used to fake out unused random calls in random_systat */
80void
81random_null_func(void)
82{
83}
84
85/* ARGSUSED */
86static int
87random_close(dev_t dev __unused, int flags, int fmt __unused,
88    struct thread *td)
89{
90	if ((flags & FWRITE) && (suser(td) == 0)
91	    && (securelevel_gt(td->td_ucred, 0) == 0)) {
92		mtx_lock(&random_systat.lock);
93		(*random_systat.reseed)();
94		random_systat.seeded = 1;
95		mtx_unlock(&random_systat.lock);
96	}
97	return (0);
98}
99
100/* ARGSUSED */
101static int
102random_read(dev_t dev __unused, struct uio *uio, int flag)
103{
104	int c, error = 0;
105
106	mtx_lock(&random_systat.lock);
107
108	/* Blocking logic */
109	while (!random_systat.seeded && !error) {
110		if (flag & IO_NDELAY)
111			error = EWOULDBLOCK;
112		else
113			error = msleep(&random_systat, &random_systat.lock,
114			    PUSER | PCATCH, "block", 0);
115	}
116
117	/* The actual read */
118	if (!error) {
119		while (uio->uio_resid > 0 && !error) {
120			c = MIN(uio->uio_resid, PAGE_SIZE);
121			c = (*random_systat.read)(random_buf, c);
122			error = uiomove(random_buf, c, uio);
123		}
124	}
125
126	mtx_unlock(&random_systat.lock);
127
128	return (error);
129}
130
131/* ARGSUSED */
132static int
133random_write(dev_t dev __unused, struct uio *uio, int flag __unused)
134{
135	int c, error = 0;
136
137	mtx_lock(&random_systat.lock);
138	while (uio->uio_resid > 0) {
139		c = MIN((int)uio->uio_resid, PAGE_SIZE);
140		error = uiomove(random_buf, c, uio);
141		if (error)
142			break;
143		(*random_systat.write)(random_buf, c);
144	}
145	mtx_unlock(&random_systat.lock);
146	return (error);
147}
148
149/* ARGSUSED */
150static int
151random_ioctl(dev_t dev __unused, u_long cmd, caddr_t addr __unused,
152    int flags __unused, struct thread *td __unused)
153{
154	int error = 0;
155
156	switch (cmd) {
157		/* Really handled in upper layer */
158	case FIOASYNC:
159	case FIONBIO:
160		break;
161	default:
162		error = ENOTTY;
163	}
164	return (error);
165}
166
167/* ARGSUSED */
168static int
169random_poll(dev_t dev __unused, int events, struct thread *td)
170{
171	int revents = 0;
172
173	if (events & (POLLIN | POLLRDNORM)) {
174		if (random_systat.seeded)
175			revents = events & (POLLIN | POLLRDNORM);
176		else
177			selrecord(td, &random_systat.rsel);
178	}
179	return (revents);
180}
181
182/* ARGSUSED */
183static int
184random_modevent(module_t mod __unused, int type, void *data __unused)
185{
186	int error = 0;
187
188	switch (type) {
189	case MOD_LOAD:
190		random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
191		random_ident_hardware(&random_systat);
192		mtx_init(&random_systat.lock, "entropy device lock",
193		    NULL, MTX_DEF);
194		(*random_systat.init)();
195
196		printf("random: <entropy source, %s>\n", random_systat.ident);
197
198		random_dev = make_dev(&random_cdevsw, RANDOM_MINOR,
199		    UID_ROOT, GID_WHEEL, 0666, "random");
200		make_dev_alias(random_dev, "urandom");	/* XXX Deprecated */
201
202		break;
203
204	case MOD_UNLOAD:
205		(*random_systat.deinit)();
206		free(random_buf, M_TEMP);
207		mtx_destroy(&random_systat.lock);
208
209		destroy_dev(random_dev);
210
211		break;
212
213	case MOD_SHUTDOWN:
214		break;
215
216	}
217	return (error);
218}
219
220DEV_MODULE(random, random_modevent, NULL);
221