randomdev.c revision 129876 
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 129876 2004-05-30 17:57:46Z phk $");
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/proc.h>
45#include <sys/selinfo.h>
46#include <sys/uio.h>
47#include <sys/unistd.h>
48#include <sys/vnode.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_flags = D_NEEDGIANT,
66	.d_close = random_close,
67	.d_read = random_read,
68	.d_write = random_write,
69	.d_ioctl = random_ioctl,
70	.d_poll = random_poll,
71	.d_name = "random",
72};
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		(*random_systat.reseed)();
93		random_systat.seeded = 1;
94	}
95
96	return (0);
97}
98
99/* ARGSUSED */
100static int
101random_read(dev_t dev __unused, struct uio *uio, int flag)
102{
103	int c, error = 0;
104	void *random_buf;
105
106	/* Blocking logic */
107	while (!random_systat.seeded && !error) {
108		if (flag & IO_NDELAY)
109			error = EWOULDBLOCK;
110		else {
111			/* No complaints please. This is temporary! */
112			printf("Entropy device is blocking. "
113			    "Dance fandango on keyboard to unblock.\n");
114			error = tsleep(&random_systat,
115			    PUSER | PCATCH, "block", 0);
116		}
117	}
118
119	/* The actual read */
120	if (!error) {
121
122		random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
123
124		while (uio->uio_resid > 0 && !error) {
125			c = MIN(uio->uio_resid, PAGE_SIZE);
126			c = (*random_systat.read)(random_buf, c);
127			error = uiomove(random_buf, c, uio);
128		}
129
130		free(random_buf, M_TEMP);
131
132	}
133
134	return (error);
135}
136
137/* ARGSUSED */
138static int
139random_write(dev_t dev __unused, struct uio *uio, int flag __unused)
140{
141	int c, error = 0;
142	void *random_buf;
143
144	random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
145
146	while (uio->uio_resid > 0) {
147		c = MIN((int)uio->uio_resid, PAGE_SIZE);
148		error = uiomove(random_buf, c, uio);
149		if (error)
150			break;
151		(*random_systat.write)(random_buf, c);
152	}
153
154	free(random_buf, M_TEMP);
155
156	return (error);
157}
158
159/* ARGSUSED */
160static int
161random_ioctl(dev_t dev __unused, u_long cmd, caddr_t addr __unused,
162    int flags __unused, struct thread *td __unused)
163{
164	int error = 0;
165
166	switch (cmd) {
167		/* Really handled in upper layer */
168	case FIOASYNC:
169	case FIONBIO:
170		break;
171	default:
172		error = ENOTTY;
173	}
174	return (error);
175}
176
177/* ARGSUSED */
178static int
179random_poll(dev_t dev __unused, int events, struct thread *td)
180{
181	int revents = 0;
182
183	if (events & (POLLIN | POLLRDNORM)) {
184		if (random_systat.seeded)
185			revents = events & (POLLIN | POLLRDNORM);
186		else
187			selrecord(td, &random_systat.rsel);
188	}
189	return (revents);
190}
191
192/* ARGSUSED */
193static int
194random_modevent(module_t mod __unused, int type, void *data __unused)
195{
196	int error = 0;
197
198	switch (type) {
199	case MOD_LOAD:
200		random_ident_hardware(&random_systat);
201		(*random_systat.init)();
202
203		printf("random: <entropy source, %s>\n", random_systat.ident);
204
205		random_dev = make_dev(&random_cdevsw, RANDOM_MINOR,
206		    UID_ROOT, GID_WHEEL, 0666, "random");
207		make_dev_alias(random_dev, "urandom");	/* XXX Deprecated */
208
209		break;
210
211	case MOD_UNLOAD:
212		(*random_systat.deinit)();
213
214		destroy_dev(random_dev);
215
216		break;
217
218	case MOD_SHUTDOWN:
219		break;
220
221	}
222	return (error);
223}
224
225DEV_MODULE(random, random_modevent, NULL);
226