summaryrefslogtreecommitdiff
path: root/udev/lib/libudev-monitor.c
blob: 7a0cb478526baaf625e4a89ad531c81bce725940 (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
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
/*
 * libudev - interface to udev device information
 *
 * Copyright (C) 2008-2009 Kay Sievers <kay.sievers@vrfy.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <dirent.h>
#include <sys/poll.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <linux/netlink.h>
#include <linux/filter.h>

#include "libudev.h"
#include "libudev-private.h"

struct udev_monitor {
	struct udev *udev;
	int refcount;
	int sock;
	struct sockaddr_nl snl;
	struct sockaddr_nl snl_trusted_sender;
	struct sockaddr_nl snl_destination;
	struct sockaddr_un sun;
	socklen_t addrlen;
	struct udev_list_node filter_subsystem_list;
};

enum udev_monitor_netlink_group {
	UDEV_MONITOR_NONE,
	UDEV_MONITOR_KERNEL,
	UDEV_MONITOR_UDEV,
};

#define UDEV_MONITOR_MAGIC		0xcafe1dea
struct udev_monitor_netlink_header {
	/* udev version text */
	char version[16];
	/*
	 * magic to protect against daemon <-> library message format mismatch
	 * used in the kernel from socket filter rules; needs to be stored in network order
	 */
	unsigned int magic;
	/* properties buffer */
	unsigned short properties_off;
	unsigned short properties_len;
	/*
	 * hashes of some common device properties strings to filter with socket filters in
	 * the client used in the kernel from socket filter rules; needs to be stored in
	 * network order
	 */
	unsigned int filter_subsystem;
	unsigned int filter_devtype;
};

static struct udev_monitor *udev_monitor_new(struct udev *udev)
{
	struct udev_monitor *udev_monitor;

	udev_monitor = calloc(1, sizeof(struct udev_monitor));
	if (udev_monitor == NULL)
		return NULL;
	udev_monitor->refcount = 1;
	udev_monitor->udev = udev;
	udev_list_init(&udev_monitor->filter_subsystem_list);
	return udev_monitor;
}

/**
 * udev_monitor_new_from_socket:
 * @udev: udev library context
 * @socket_path: unix socket path
 *
 * Create new udev monitor and connect to a specified socket. The
 * path to a socket either points to an existing socket file, or if
 * the socket path starts with a '@' character, an abstract namespace
 * socket will be used.
 *
 * A socket file will not be created. If it does not already exist,
 * it will fall-back and connect to an abstract namespace socket with
 * the given path. The permissions adjustment of a socket file, as
 * well as the later cleanup, needs to be done by the caller.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the resources of the udev monitor.
 *
 * Returns: a new udev monitor, or #NULL, in case of an error
 **/
struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
{
	struct udev_monitor *udev_monitor;
	struct stat statbuf;

	if (udev == NULL)
		return NULL;
	if (socket_path == NULL)
		return NULL;
	udev_monitor = udev_monitor_new(udev);
	if (udev_monitor == NULL)
		return NULL;

	udev_monitor->sun.sun_family = AF_LOCAL;
	if (socket_path[0] == '@') {
		/* translate leading '@' to abstract namespace */
		util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
		udev_monitor->sun.sun_path[0] = '\0';
		udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
	} else if (stat(socket_path, &statbuf) == 0 && S_ISSOCK(statbuf.st_mode)) {
		/* existing socket file */
		util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
		udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
	} else {
		/* no socket file, assume abstract namespace socket */
		util_strscpy(&udev_monitor->sun.sun_path[1], sizeof(udev_monitor->sun.sun_path)-1, socket_path);
		udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path)+1;
	}
	udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
	if (udev_monitor->sock == -1) {
		err(udev, "error getting socket: %m\n");
		free(udev_monitor);
		return NULL;
	}
	util_set_fd_cloexec(udev_monitor->sock);

	dbg(udev, "monitor %p created with '%s'\n", udev_monitor, socket_path);
	return udev_monitor;
}

/**
 * udev_monitor_new_from_netlink:
 * @udev: udev library context
 * @name: name of event source
 *
 * Create new udev monitor and connect to a specified event
 * source. Valid sources identifiers are "udev" and "kernel".
 *
 * Applications should usually not connect directly to the
 * "kernel" events, because the devices might not be useable
 * at that time, before udev has configured them, and created
 * device nodes.
 *
 * Accessing devices at the same time as udev, might result
 * in unpredictable behavior.
 *
 * The "udev" events are sent out after udev has finished its
 * event processing, all rules have been processed, and needed
 * device nodes are created.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the resources of the udev monitor.
 *
 * Returns: a new udev monitor, or #NULL, in case of an error
 **/
struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
{
	struct udev_monitor *udev_monitor;
	unsigned int group;

	if (udev == NULL)
		return NULL;

	if (name == NULL)
		group = UDEV_MONITOR_NONE;
	else if (strcmp(name, "udev") == 0)
		group = UDEV_MONITOR_UDEV;
	else if (strcmp(name, "kernel") == 0)
		group = UDEV_MONITOR_KERNEL;
	else
		return NULL;

	udev_monitor = udev_monitor_new(udev);
	if (udev_monitor == NULL)
		return NULL;

	udev_monitor->sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
	if (udev_monitor->sock == -1) {
		err(udev, "error getting socket: %m\n");
		free(udev_monitor);
		return NULL;
	}
	util_set_fd_cloexec(udev_monitor->sock);

	udev_monitor->snl.nl_family = AF_NETLINK;
	udev_monitor->snl.nl_groups = group;

	/* default destination for sending */
	udev_monitor->snl_destination.nl_family = AF_NETLINK;
	udev_monitor->snl_destination.nl_groups = UDEV_MONITOR_UDEV;

	dbg(udev, "monitor %p created with NETLINK_KOBJECT_UEVENT (%u)\n", udev_monitor, group);
	return udev_monitor;
}

static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
			    unsigned short code, unsigned int data)
{
	struct sock_filter *ins = &inss[*i];

	ins->code = code;
	ins->k = data;
	(*i)++;
}

static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
			   unsigned short code, unsigned int data,
			   unsigned short jt, unsigned short jf)
{
	struct sock_filter *ins = &inss[*i];

	ins->code = code;
	ins->jt = jt;
	ins->jf = jf;
	ins->k = data;
	(*i)++;
}

int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
{
	static struct sock_filter ins[256];
	static struct sock_fprog filter;
	unsigned int i;
	struct udev_list_entry *list_entry;
	int err;

	if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
		return 0;

	memset(ins, 0x00, sizeof(ins));
	i = 0;

	/* load magic in A */
	bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
	/* jump if magic matches */
	bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
	/* wrong magic, pass packet */
	bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);

	/* add all subsystem match values */
	udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
		unsigned int hash;

		/* load filter_subsystem value in A */
		bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem));
		hash = util_string_hash32(udev_list_entry_get_name(list_entry));
		if (udev_list_entry_get_value(list_entry) == NULL) {
			/* jump if subsystem does not match */
			bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
		} else {
			/* jump if subsystem does not match */
			bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);

			/* load filter_devtype value in A */
			bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype));
			/* jump if value does not match */
			hash = util_string_hash32(udev_list_entry_get_value(list_entry));
			bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
		}

		/* matched, pass packet */
		bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);

		if (i+1 >= ARRAY_SIZE(ins))
			return -1;
	}
	/* nothing matched, drop packet */
	bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);

	/* install filter */
	filter.len = i;
	filter.filter = ins;
	err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
	return err;
}

int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
{
	udev_monitor->snl_trusted_sender.nl_pid = sender->snl.nl_pid;
	return 0;
}

int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
{
	int err;
	const int on = 1;

	if (udev_monitor->sun.sun_family != 0) {
		err = bind(udev_monitor->sock,
			   (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
	} else if (udev_monitor->snl.nl_family != 0) {
		udev_monitor_filter_update(udev_monitor);
		err = bind(udev_monitor->sock,
			   (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
		if (err == 0) {
			struct sockaddr_nl snl;
			socklen_t addrlen;

			/*
			 * get the address the kernel has assigned us
			 * it is usually, but not neccessarily the pid
			 */
			addrlen = sizeof(struct sockaddr_nl);
			err = getsockname(udev_monitor->sock, (struct sockaddr *)&snl, &addrlen);
			if (err == 0)
				udev_monitor->snl.nl_pid = snl.nl_pid;
		}
	} else {
		return -EINVAL;
	}

	if (err < 0) {
		err(udev_monitor->udev, "bind failed: %m\n");
		return err;
	}

	/* enable receiving of sender credentials */
	setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
	return 0;
}

int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
{
	if (udev_monitor == NULL)
		return -1;
	return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
}

int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
{
	int err;

	err = close(udev_monitor->sock);
	udev_monitor->sock = -1;
	return err;
}

/**
 * udev_monitor_ref:
 * @udev_monitor: udev monitor
 *
 * Take a reference of a udev monitor.
 *
 * Returns: the passed udev monitor
 **/
struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
{
	if (udev_monitor == NULL)
		return NULL;
	udev_monitor->refcount++;
	return udev_monitor;
}

/**
 * udev_monitor_unref:
 * @udev_monitor: udev monitor
 *
 * Drop a reference of a udev monitor. If the refcount reaches zero,
 * the bound socket will be closed, and the resources of the monitor
 * will be released.
 *
 **/
void udev_monitor_unref(struct udev_monitor *udev_monitor)
{
	if (udev_monitor == NULL)
		return;
	udev_monitor->refcount--;
	if (udev_monitor->refcount > 0)
		return;
	if (udev_monitor->sock >= 0)
		close(udev_monitor->sock);
	udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_subsystem_list);
	dbg(udev_monitor->udev, "monitor %p released\n", udev_monitor);
	free(udev_monitor);
}

/**
 * udev_monitor_get_udev:
 * @udev_monitor: udev monitor
 *
 * Retrieve the udev library context the monitor was created with.
 *
 * Returns: the udev library context
 **/
struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
{
	if (udev_monitor == NULL)
		return NULL;
	return udev_monitor->udev;
}

/**
 * udev_monitor_get_fd:
 * @udev_monitor: udev monitor
 *
 * Retrieve the socket file descriptor associated with the monitor.
 *
 * Returns: the socket file descriptor
 **/
int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
{
	if (udev_monitor == NULL)
		return -1;
	return udev_monitor->sock;
}

static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
{
	struct udev_list_entry *list_entry;

	if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
		return 1;

	udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
		const char *subsys = udev_list_entry_get_name(list_entry);
		const char *dsubsys = udev_device_get_subsystem(udev_device);
		const char *devtype;
		const char *ddevtype;

		if (strcmp(dsubsys, subsys) != 0)
			continue;

		devtype = udev_list_entry_get_value(list_entry);
		if (devtype == NULL)
			return 1;
		ddevtype = udev_device_get_devtype(udev_device);
		if (ddevtype == NULL)
			continue;
		if (strcmp(ddevtype, devtype) == 0)
			return 1;
	}
	return 0;
}

/**
 * udev_monitor_receive_device:
 * @udev_monitor: udev monitor
 *
 * Receive data from the udev monitor socket, allocate a new udev
 * device, fill in the received data, and return the device.
 *
 * Only socket connections with uid=0 are accepted. The caller
 * needs to make sure that there is data to read from the socket.
 * The call will block until the socket becomes readable.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the resources of the udev device.
 *
 * Returns: a new udev device, or #NULL, in case of an error
 **/
struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
{
	struct udev_device *udev_device;
	struct msghdr smsg;
	struct iovec iov;
	char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
	struct cmsghdr *cmsg;
	struct sockaddr_nl snl;
	struct ucred *cred;
	char buf[8192];
	ssize_t buflen;
	ssize_t bufpos;
	struct udev_monitor_netlink_header *nlh;
	int devpath_set = 0;
	int subsystem_set = 0;
	int action_set = 0;
	int maj = 0;
	int min = 0;
	int is_kernel = 0;

retry:
	if (udev_monitor == NULL)
		return NULL;
	memset(buf, 0x00, sizeof(buf));
	iov.iov_base = &buf;
	iov.iov_len = sizeof(buf);
	memset (&smsg, 0x00, sizeof(struct msghdr));
	smsg.msg_iov = &iov;
	smsg.msg_iovlen = 1;
	smsg.msg_control = cred_msg;
	smsg.msg_controllen = sizeof(cred_msg);

	if (udev_monitor->snl.nl_family != 0) {
		smsg.msg_name = &snl;
		smsg.msg_namelen = sizeof(snl);
	}

	buflen = recvmsg(udev_monitor->sock, &smsg, 0);
	if (buflen < 0) {
		if (errno != EINTR)
			info(udev_monitor->udev, "unable to receive message\n");
		return NULL;
	}

	if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
		info(udev_monitor->udev, "invalid message length\n");
		return NULL;
	}

	if (udev_monitor->snl.nl_family != 0) {
		if (snl.nl_groups == 0) {
			/* unicast message, check if we trust the sender */
			if (udev_monitor->snl_trusted_sender.nl_pid == 0 ||
			    snl.nl_pid != udev_monitor->snl_trusted_sender.nl_pid) {
				info(udev_monitor->udev, "unicast netlink message ignored\n");
				return NULL;
			}
		} else if (snl.nl_groups == UDEV_MONITOR_KERNEL) {
			if (snl.nl_pid > 0) {
				info(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n", snl.nl_pid);
				return NULL;
			}
			is_kernel = 1;
		}
	}

	cmsg = CMSG_FIRSTHDR(&smsg);
	if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
		info(udev_monitor->udev, "no sender credentials received, message ignored\n");
		return NULL;
	}

	cred = (struct ucred *)CMSG_DATA(cmsg);
	if (cred->uid != 0) {
		info(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
		return NULL;
	}

	if (strncmp(buf, "udev-", 5) == 0) {
		/* udev message needs proper version magic */
		nlh = (struct udev_monitor_netlink_header *) buf;
		if (nlh->magic != htonl(UDEV_MONITOR_MAGIC))
			return NULL;
		if (nlh->properties_off < sizeof(struct udev_monitor_netlink_header))
			return NULL;
		if (nlh->properties_off+32 > buflen)
			return NULL;
		bufpos = nlh->properties_off;
	} else {
		/* kernel message with header */
		bufpos = strlen(buf) + 1;
		if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
			info(udev_monitor->udev, "invalid message length\n");
			return NULL;
		}

		/* check message header */
		if (strstr(buf, "@/") == NULL) {
			info(udev_monitor->udev, "unrecognized message header\n");
			return NULL;
		}
	}

	udev_device = device_new(udev_monitor->udev);
	if (udev_device == NULL) {
		return NULL;
	}

	while (bufpos < buflen) {
		char *key;
		size_t keylen;

		key = &buf[bufpos];
		keylen = strlen(key);
		if (keylen == 0)
			break;
		bufpos += keylen + 1;

		if (strncmp(key, "DEVPATH=", 8) == 0) {
			char path[UTIL_PATH_SIZE];

			util_strscpyl(path, sizeof(path), udev_get_sys_path(udev_monitor->udev), &key[8], NULL);
			udev_device_set_syspath(udev_device, path);
			devpath_set = 1;
		} else if (strncmp(key, "SUBSYSTEM=", 10) == 0) {
			udev_device_set_subsystem(udev_device, &key[10]);
			subsystem_set = 1;
		} else if (strncmp(key, "DEVTYPE=", 8) == 0) {
			udev_device_set_devtype(udev_device, &key[8]);
		} else if (strncmp(key, "DEVNAME=", 8) == 0) {
			if (is_kernel)
				udev_device_set_knodename(udev_device, &key[8]);
			else
				udev_device_set_devnode(udev_device, &key[8]);
		} else if (strncmp(key, "DEVLINKS=", 9) == 0) {
			char devlinks[UTIL_PATH_SIZE];
			char *slink;
			char *next;

			util_strscpy(devlinks, sizeof(devlinks), &key[9]);
			slink = devlinks;
			next = strchr(slink, ' ');
			while (next != NULL) {
				next[0] = '\0';
				udev_device_add_devlink(udev_device, slink);
				slink = &next[1];
				next = strchr(slink, ' ');
			}
			if (slink[0] != '\0')
				udev_device_add_devlink(udev_device, slink);
		} else if (strncmp(key, "DRIVER=", 7) == 0) {
			udev_device_set_driver(udev_device, &key[7]);
		} else if (strncmp(key, "ACTION=", 7) == 0) {
			udev_device_set_action(udev_device, &key[7]);
			action_set = 1;
		} else if (strncmp(key, "MAJOR=", 6) == 0) {
			maj = strtoull(&key[6], NULL, 10);
		} else if (strncmp(key, "MINOR=", 6) == 0) {
			min = strtoull(&key[6], NULL, 10);
		} else if (strncmp(key, "DEVPATH_OLD=", 12) == 0) {
			udev_device_set_devpath_old(udev_device, &key[12]);
		} else if (strncmp(key, "SEQNUM=", 7) == 0) {
			udev_device_set_seqnum(udev_device, strtoull(&key[7], NULL, 10));
		} else if (strncmp(key, "TIMEOUT=", 8) == 0) {
			udev_device_set_timeout(udev_device, strtoull(&key[8], NULL, 10));
		} else {
			udev_device_add_property_from_string(udev_device, key);
		}
	}
	if (!devpath_set || !subsystem_set || !action_set) {
		info(udev_monitor->udev, "missing values, skip\n");
		udev_device_unref(udev_device);
		return NULL;
	}

	/* skip device, if it does not pass the current filter */
	if (!passes_filter(udev_monitor, udev_device)) {
		struct pollfd pfd[1];
		int rc;

		udev_device_unref(udev_device);

		/* if something is queued, get next device */
		pfd[0].fd = udev_monitor->sock;
		pfd[0].events = POLLIN;
		rc = poll(pfd, 1, 0);
		if (rc > 0)
			goto retry;
		return NULL;
	}

	if (maj > 0)
		udev_device_set_devnum(udev_device, makedev(maj, min));
	udev_device_set_info_loaded(udev_device);
	return udev_device;
}

int udev_monitor_send_device(struct udev_monitor *udev_monitor,
			     struct udev_monitor *destination, struct udev_device *udev_device)
{
	struct msghdr smsg;
	struct iovec iov[2];
	const char *buf;
	ssize_t blen;
	ssize_t count;

	blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
	if (blen < 32)
		return -1;

	if (udev_monitor->sun.sun_family != 0) {
		const char *action;
		char header[2048];
		char *s;

		/* header <action>@<devpath> */
		action = udev_device_get_action(udev_device);
		if (action == NULL)
			return -EINVAL;
		s = header;
		if (util_strpcpyl(&s, sizeof(header), action, "@", udev_device_get_devpath(udev_device), NULL) == 0)
			return -EINVAL;
		iov[0].iov_base = header;
		iov[0].iov_len = (s - header)+1;

		/* add properties list */
		iov[1].iov_base = (char *)buf;
		iov[1].iov_len = blen;

		memset(&smsg, 0x00, sizeof(struct msghdr));
		smsg.msg_iov = iov;
		smsg.msg_iovlen = 2;
		smsg.msg_name = &udev_monitor->sun;
		smsg.msg_namelen = udev_monitor->addrlen;
	} else if (udev_monitor->snl.nl_family != 0) {
		const char *val;
		struct udev_monitor_netlink_header nlh;


		/* add versioned header */
		memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header));
		util_strscpy(nlh.version, sizeof(nlh.version), "udev-" VERSION);
		nlh.magic = htonl(UDEV_MONITOR_MAGIC);
		val = udev_device_get_subsystem(udev_device);
		nlh.filter_subsystem = htonl(util_string_hash32(val));
		val = udev_device_get_devtype(udev_device);
		if (val != NULL)
			nlh.filter_devtype = htonl(util_string_hash32(val));
		iov[0].iov_base = &nlh;
		iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);

		/* add properties list */
		nlh.properties_off = iov[0].iov_len;
		nlh.properties_len = blen;
		iov[1].iov_base = (char *)buf;
		iov[1].iov_len = blen;

		memset(&smsg, 0x00, sizeof(struct msghdr));
		smsg.msg_iov = iov;
		smsg.msg_iovlen = 2;
		/*
		 * Use custom address for target, or the default one.
		 *
		 * If we send to a muticast group, we will get
		 * ECONNREFUSED, which is expected.
		 */
		if (destination != NULL)
			smsg.msg_name = &destination->snl;
		else
			smsg.msg_name = &udev_monitor->snl_destination;
		smsg.msg_namelen = sizeof(struct sockaddr_nl);
	} else {
		return -1;
	}

	count = sendmsg(udev_monitor->sock, &smsg, 0);
	info(udev_monitor->udev, "passed %zi bytes to monitor %p\n", count, udev_monitor);
	return count;
}

int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
{
	if (udev_monitor == NULL)
		return -EINVAL;
	if (subsystem == NULL)
		return 0;
	if (udev_list_entry_add(udev_monitor->udev,
				&udev_monitor->filter_subsystem_list, subsystem, devtype, 0, 0) == NULL)
		return -ENOMEM;
	return 0;
}

int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
{
	static struct sock_fprog filter = { 0, NULL };

	udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_subsystem_list);
	return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
}