summaryrefslogtreecommitdiffstats
path: root/sys/dev/random/randomdev.c
blob: e30e9ae9da3b07d944ca68f0de30fc4a09417bb7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
/*-
 * Copyright (c) 2000 Mark R V Murray
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer
 *    in this position and unchanged.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $FreeBSD$
 */

#include <sys/param.h>
#include <sys/queue.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/uio.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/bus.h>
#include <sys/poll.h>
#include <sys/selinfo.h>
#include <sys/random.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <sys/unistd.h>

#include <machine/bus.h>
#include <machine/cpu.h>
#include <machine/resource.h>

#include <dev/random/randomdev.h>

static d_open_t		random_open;
static d_close_t	random_close;
static d_read_t		random_read;
static d_write_t	random_write;
static d_ioctl_t	random_ioctl;
static d_poll_t		random_poll;

#define CDEV_MAJOR	2
#define RANDOM_MINOR	3

static struct cdevsw random_cdevsw = {
	/* open */	random_open,
	/* close */	random_close,
	/* read */	random_read,
	/* write */	random_write,
	/* ioctl */	random_ioctl,
	/* poll */	random_poll,
	/* mmap */	nommap,
	/* strategy */	nostrategy,
	/* name */	"random",
	/* maj */	CDEV_MAJOR,
	/* dump */	nodump,
	/* psize */	nopsize,
	/* flags */	0,
	/* bmaj */	-1
};

static void random_kthread(void *);
static void random_harvest_internal(u_int64_t, void *, u_int, u_int, u_int, enum esource);
static void random_write_internal(void *, u_int);

/* Ring buffer holding harvested entropy */
static struct harvestring {
	volatile u_int	head;
	volatile u_int	tail;
	struct harvest	data[HARVEST_RING_SIZE];
} harvestring;

static struct random_systat {
	u_int		seeded;	/* 0 causes blocking 1 allows normal output */
	u_int		burst;	/* number of events to do before sleeping */
	struct selinfo	rsel;	/* For poll(2) */
} random_systat;

/* <0 to end the kthread, 0 to let it run */
static int random_kthread_control = 0;

static struct proc *random_kthread_proc;

/* For use with make_dev(9)/destroy_dev(9). */
static dev_t	random_dev;
static dev_t	urandom_dev;

static int
random_check_boolean(SYSCTL_HANDLER_ARGS)
{
	if (oidp->oid_arg1 != NULL && *(u_int *)(oidp->oid_arg1) != 0)
		*(u_int *)(oidp->oid_arg1) = 1;
        return sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
}

RANDOM_CHECK_UINT(burst, 0, 20);

SYSCTL_NODE(_kern, OID_AUTO, random, CTLFLAG_RW,
	0, "Random Number Generator");
SYSCTL_NODE(_kern_random, OID_AUTO, sys, CTLFLAG_RW,
	0, "Entropy Device Parameters");
SYSCTL_PROC(_kern_random_sys, OID_AUTO, seeded,
	CTLTYPE_INT|CTLFLAG_RW, &random_systat.seeded, 1,
	random_check_boolean, "I", "Seeded State");
SYSCTL_PROC(_kern_random_sys, OID_AUTO, burst,
	CTLTYPE_INT|CTLFLAG_RW, &random_systat.burst, 20,
	random_check_uint_burst, "I", "Harvest Burst Size");
SYSCTL_NODE(_kern_random_sys, OID_AUTO, harvest, CTLFLAG_RW,
	0, "Entropy Sources");
SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, ethernet,
	CTLTYPE_INT|CTLFLAG_RW, &harvest.ethernet, 0,
	random_check_boolean, "I", "Harvest NIC entropy");
SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, point_to_point,
	CTLTYPE_INT|CTLFLAG_RW, &harvest.point_to_point, 0,
	random_check_boolean, "I", "Harvest serial net entropy");
SYSCTL_PROC(_kern_random_sys_harvest, OID_AUTO, interrupt,
	CTLTYPE_INT|CTLFLAG_RW, &harvest.interrupt, 0,
	random_check_boolean, "I", "Harvest IRQ entropy");

static int
random_open(dev_t dev, int flags, int fmt, struct proc *p)
{
	if ((flags & FWRITE) && (securelevel > 0 || suser(p)))
		return EPERM;
	else
		return 0;
}

static int
random_close(dev_t dev, int flags, int fmt, struct proc *p)
{
	if ((flags & FWRITE) && !(securelevel > 0 || suser(p)))
		random_reseed();
	return 0;
}

static int
random_read(dev_t dev, struct uio *uio, int flag)
{
	u_int	c, ret;
	int	error = 0;
	void	*random_buf;

	while (!random_systat.seeded) {
		if (flag & IO_NDELAY)
			error =  EWOULDBLOCK;
		else
			error = tsleep(&random_systat, PUSER|PCATCH,
				"block", 0);
		if (error != 0)
			return error;
	}
	c = min(uio->uio_resid, PAGE_SIZE);
	random_buf = (void *)malloc(c, M_TEMP, M_WAITOK);
	while (uio->uio_resid > 0 && error == 0) {
		ret = read_random_real(random_buf, c);
		error = uiomove(random_buf, ret, uio);
	}
	free(random_buf, M_TEMP);
	return error;
}

static int
random_write(dev_t dev, struct uio *uio, int flag)
{
	u_int	c;
	int	error;
	void	*random_buf;

	error = 0;
	random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
	while (uio->uio_resid > 0) {
		c = min(uio->uio_resid, PAGE_SIZE);
		error = uiomove(random_buf, c, uio);
		if (error)
			break;
		random_write_internal(random_buf, c);
	}
	free(random_buf, M_TEMP);
	return error;
}

static int
random_ioctl(dev_t dev, u_long cmd, caddr_t addr, int flags, struct proc *p)
{
	return ENOTTY;
}

static int
random_poll(dev_t dev, int events, struct proc *p)
{
	int	revents;

	revents = 0;
	if (events & (POLLIN | POLLRDNORM)) {
		if (random_systat.seeded)
			revents = events & (POLLIN | POLLRDNORM);
		else
			selrecord(p, &random_systat.rsel);
	}
	return revents;
}

static int
random_modevent(module_t mod, int type, void *data)
{
	int	error;

	switch(type) {
	case MOD_LOAD:
		random_init();

		/* This can be turned off by the very paranoid
		 * a reseed will turn it back on.
		 */
		random_systat.seeded = 1;

		/* Number of envents to process off the harvest
		 * queue before giving it a break and sleeping
		 */
		random_systat.burst = 20;

		/* Initialise the harvest ringbuffer */
		harvestring.head = 0;
		harvestring.tail = 0;

		if (bootverbose)
			printf("random: <entropy source>\n");
		random_dev = make_dev(&random_cdevsw, RANDOM_MINOR, UID_ROOT,
			GID_WHEEL, 0666, "random");
		urandom_dev = make_dev_alias(random_dev, "urandom");

		/* Start the hash/reseed thread */
		error = kthread_create(random_kthread, NULL,
			&random_kthread_proc, RFHIGHPID, "random");
		if (error != 0)
			return error;

		/* Register the randomness harvesting routine */
		random_init_harvester(random_harvest_internal,
			read_random_real);

		return 0;

	case MOD_UNLOAD:
		/* Deregister the randomness harvesting routine */
		random_deinit_harvester();

		/* Command the hash/reseed thread to end and
		 * wait for it to finish
		 */
		random_kthread_control = -1;
		tsleep((void *)&random_kthread_control, PUSER, "term", 0);

		random_deinit();

		destroy_dev(random_dev);
		destroy_dev(urandom_dev);
		return 0;

	case MOD_SHUTDOWN:
		return 0;

	default:
		return EOPNOTSUPP;
	}
}

DEV_MODULE(random, random_modevent, NULL);

static void
random_kthread(void *arg /* NOTUSED */)
{
	struct harvest	*event;
	int		newtail, burst;

	/* Drain the harvest queue (in 'burst' size chunks,
	 * if 'burst' > 0. If 'burst' == 0, then completely
	 * drain the queue.
	 */
	for (burst = 0; ; burst++) {

		if ((harvestring.tail == harvestring.head) ||
			(random_systat.burst && burst == random_systat.burst)) {
				tsleep(&harvestring, PUSER, "sleep", hz/10);
				burst = 0;

		}
		else {

			/* Suck a harvested entropy event out of the queue and
			 * hand it to the event processor
			 */

			newtail = (harvestring.tail + 1) & HARVEST_RING_MASK;
			event = &harvestring.data[harvestring.tail];

			/* Bump the ring counter. This action is assumed
			 * to be atomic.
			 */
			harvestring.tail = newtail;

			random_process_event(event);

		}

		/* Is the thread scheduled for a shutdown? */
		if (random_kthread_control != 0) {
#ifdef DEBUG
			mtx_lock(&Giant);
			printf("Random kthread setting terminate\n");
			mtx_unlock(&Giant);
#endif
			random_set_wakeup_exit(&random_kthread_control);
			/* NOTREACHED */
			break;
		}

	}

}

/* Entropy harvesting routine. This is supposed to be fast; do
 * not do anything slow in here!
 */
static void
random_harvest_internal(u_int64_t somecounter, void *entropy, u_int count,
	u_int bits, u_int frac, enum esource origin)
{
	struct harvest	*harvest;
	int		newhead;

	newhead = (harvestring.head + 1) & HARVEST_RING_MASK;

	if (newhead != harvestring.tail) {

		/* Add the harvested data to the ring buffer */

		harvest = &harvestring.data[harvestring.head];

		/* Stuff the harvested data into the ring */
		harvest->somecounter = somecounter;
		count = count > HARVESTSIZE ? HARVESTSIZE : count;
		memcpy(harvest->entropy, entropy, count);
		harvest->size = count;
		harvest->bits = bits;
		harvest->frac = frac;
		harvest->source = origin < ENTROPYSOURCE ? origin : 0;

		/* Bump the ring counter. This action is assumed
		 * to be atomic.
		 */
		harvestring.head = newhead;

	}

}

static void
random_write_internal(void *buf, u_int count)
{
	u_int	i;

	/* Break the input up into HARVESTSIZE chunks.
	 * The writer has too much control here, so "estimate" the
	 * the entropy as zero.
	 */
	for (i = 0; i < count; i += HARVESTSIZE) {
		random_harvest_internal(get_cyclecount(), (char *)buf + i,
			HARVESTSIZE, 0, 0, RANDOM_WRITE);
	}

	/* Maybe the loop iterated at least once */
	if (i > count)
		i -= HARVESTSIZE;

	/* Get the last bytes even if the input length is not
	 * a multiple of HARVESTSIZE.
	 */
	count %= HARVESTSIZE;
	if (count) {
		random_harvest_internal(get_cyclecount(), (char *)buf + i,
			count, 0, 0, RANDOM_WRITE);
	}
}

void
random_unblock(void)
{
	if (!random_systat.seeded) {
		random_systat.seeded = 1;
		selwakeup(&random_systat.rsel);
		wakeup(&random_systat);
	}
}
OpenPOWER on IntegriCloud