2 This file is part of systemd.
4 Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
6 systemd is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version.
11 systemd is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public License
17 along with systemd; If not, see <http://www.gnu.org/licenses/>.
29 #include <sys/socket.h>
31 #include <arpa/inet.h>
32 #include <linux/netlink.h>
33 #include <linux/filter.h>
36 #include "libudev-private.h"
37 #include "socket-util.h"
41 * SECTION:libudev-monitor
42 * @short_description: device event source
44 * Connects to a device event source.
50 * Opaque object handling an event source.
56 union sockaddr_union snl;
57 union sockaddr_union snl_trusted_sender;
58 union sockaddr_union snl_destination;
60 struct udev_list filter_subsystem_list;
61 struct udev_list filter_tag_list;
65 enum udev_monitor_netlink_group {
71 #define UDEV_MONITOR_MAGIC 0xfeedcafe
72 struct udev_monitor_netlink_header {
73 /* "libudev" prefix to distinguish libudev and kernel messages */
76 * magic to protect against daemon <-> library message format mismatch
77 * used in the kernel from socket filter rules; needs to be stored in network order
80 /* total length of header structure known to the sender */
81 unsigned int header_size;
82 /* properties string buffer */
83 unsigned int properties_off;
84 unsigned int properties_len;
86 * hashes of primary device properties strings, to let libudev subscribers
87 * use in-kernel socket filters; values need to be stored in network order
89 unsigned int filter_subsystem_hash;
90 unsigned int filter_devtype_hash;
91 unsigned int filter_tag_bloom_hi;
92 unsigned int filter_tag_bloom_lo;
95 static struct udev_monitor *udev_monitor_new(struct udev *udev)
97 struct udev_monitor *udev_monitor;
99 udev_monitor = calloc(1, sizeof(struct udev_monitor));
100 if (udev_monitor == NULL)
102 udev_monitor->refcount = 1;
103 udev_monitor->udev = udev;
104 udev_list_init(udev, &udev_monitor->filter_subsystem_list, false);
105 udev_list_init(udev, &udev_monitor->filter_tag_list, true);
109 /* we consider udev running when /dev is on devtmpfs */
110 static bool udev_has_devtmpfs(struct udev *udev) {
111 struct file_handle *h;
113 _cleanup_fclose_ FILE *f = NULL;
114 char line[LINE_MAX], *e;
117 h = alloca(MAX_HANDLE_SZ);
119 r = name_to_handle_at(AT_FDCWD, "/dev", h, &mount_id, 0);
124 f = fopen("/proc/self/mountinfo", "re");
128 FOREACH_LINE(line, f, return false) {
129 _cleanup_free_ char *opts = NULL;
132 if (sscanf(line, "%i", &mid) != 1)
138 e = strstr(line, " - ");
142 /* accept any name that starts with the currently expected type */
143 if (startswith(e + 3, "devtmpfs"))
150 /* we consider udev running when we have running udev service */
151 static bool udev_has_service(struct udev *udev) {
152 struct udev_queue *queue;
155 queue = udev_queue_new(udev);
159 active = udev_queue_get_udev_is_active(queue);
160 udev_queue_unref(queue);
165 struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd)
167 struct udev_monitor *udev_monitor;
174 group = UDEV_MONITOR_NONE;
175 else if (streq(name, "udev"))
176 group = UDEV_MONITOR_UDEV;
177 else if (streq(name, "kernel"))
178 group = UDEV_MONITOR_KERNEL;
183 * We do not support subscribing to uevents if no instance of udev
184 * is running. Uevents would otherwise broadcast the processing data
185 * of the host into containers, which is not acceptable. Containers
186 * will currently just not get any uevents.
188 * We clear the netlink multicast group here, so the socket will
189 * not receive any messages.
191 if (!udev_has_service(udev) && !udev_has_devtmpfs(udev)) {
192 udev_dbg(udev, "udev seems not to be active, disable the monitor\n");
196 udev_monitor = udev_monitor_new(udev);
197 if (udev_monitor == NULL)
201 udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
202 if (udev_monitor->sock == -1) {
203 udev_err(udev, "error getting socket: %m\n");
208 udev_monitor->bound = true;
209 udev_monitor->sock = fd;
212 udev_monitor->snl.nl.nl_family = AF_NETLINK;
213 udev_monitor->snl.nl.nl_groups = group;
215 /* default destination for sending */
216 udev_monitor->snl_destination.nl.nl_family = AF_NETLINK;
217 udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV;
223 * udev_monitor_new_from_netlink:
224 * @udev: udev library context
225 * @name: name of event source
227 * Create new udev monitor and connect to a specified event
228 * source. Valid sources identifiers are "udev" and "kernel".
230 * Applications should usually not connect directly to the
231 * "kernel" events, because the devices might not be useable
232 * at that time, before udev has configured them, and created
233 * device nodes. Accessing devices at the same time as udev,
234 * might result in unpredictable behavior. The "udev" events
235 * are sent out after udev has finished its event processing,
236 * all rules have been processed, and needed device nodes are
239 * The initial refcount is 1, and needs to be decremented to
240 * release the resources of the udev monitor.
242 * Returns: a new udev monitor, or #NULL, in case of an error
244 _public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
246 return udev_monitor_new_from_netlink_fd(udev, name, -1);
249 static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
250 unsigned short code, unsigned int data)
252 struct sock_filter *ins = &inss[*i];
259 static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
260 unsigned short code, unsigned int data,
261 unsigned short jt, unsigned short jf)
263 struct sock_filter *ins = &inss[*i];
273 * udev_monitor_filter_update:
274 * @udev_monitor: monitor
276 * Update the installed socket filter. This is only needed,
277 * if the filter was removed or changed.
279 * Returns: 0 on success, otherwise a negative error value.
281 _public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
283 struct sock_filter ins[512];
284 struct sock_fprog filter;
286 struct udev_list_entry *list_entry;
289 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL &&
290 udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
293 memset(ins, 0x00, sizeof(ins));
296 /* load magic in A */
297 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
298 /* jump if magic matches */
299 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
300 /* wrong magic, pass packet */
301 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
303 if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) {
306 /* count tag matches, to calculate end of tag match block */
308 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list))
311 /* add all tags matches */
312 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
313 uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry));
314 uint32_t tag_bloom_hi = tag_bloom_bits >> 32;
315 uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff;
317 /* load device bloom bits in A */
318 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi));
319 /* clear bits (tag bits & bloom bits) */
320 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi);
321 /* jump to next tag if it does not match */
322 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3);
324 /* load device bloom bits in A */
325 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo));
326 /* clear bits (tag bits & bloom bits) */
327 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo);
328 /* jump behind end of tag match block if tag matches */
330 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0);
333 /* nothing matched, drop packet */
334 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
337 /* add all subsystem matches */
338 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) {
339 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
340 unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry));
342 /* load device subsystem value in A */
343 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash));
344 if (udev_list_entry_get_value(list_entry) == NULL) {
345 /* jump if subsystem does not match */
346 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
348 /* jump if subsystem does not match */
349 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
351 /* load device devtype value in A */
352 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash));
353 /* jump if value does not match */
354 hash = util_string_hash32(udev_list_entry_get_value(list_entry));
355 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
358 /* matched, pass packet */
359 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
361 if (i+1 >= ELEMENTSOF(ins))
365 /* nothing matched, drop packet */
366 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
369 /* matched, pass packet */
370 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
373 memset(&filter, 0x00, sizeof(filter));
376 err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
377 return err < 0 ? -errno : 0;
380 int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
382 udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid;
386 * udev_monitor_enable_receiving:
387 * @udev_monitor: the monitor which should receive events
389 * Binds the @udev_monitor socket to the event source.
391 * Returns: 0 on success, otherwise a negative error value.
393 _public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
398 udev_monitor_filter_update(udev_monitor);
400 if (!udev_monitor->bound) {
401 err = bind(udev_monitor->sock,
402 &udev_monitor->snl.sa, sizeof(struct sockaddr_nl));
404 udev_monitor->bound = true;
408 union sockaddr_union snl;
412 * get the address the kernel has assigned us
413 * it is usually, but not necessarily the pid
415 addrlen = sizeof(struct sockaddr_nl);
416 err = getsockname(udev_monitor->sock, &snl.sa, &addrlen);
418 udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid;
420 udev_err(udev_monitor->udev, "bind failed: %m\n");
424 /* enable receiving of sender credentials */
425 setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
430 * udev_monitor_set_receive_buffer_size:
431 * @udev_monitor: the monitor which should receive events
432 * @size: the size in bytes
434 * Set the size of the kernel socket buffer. This call needs the
435 * appropriate privileges to succeed.
437 * Returns: 0 on success, otherwise -1 on error.
439 _public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
441 if (udev_monitor == NULL)
443 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
446 int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
450 err = close(udev_monitor->sock);
451 udev_monitor->sock = -1;
452 return err < 0 ? -errno : 0;
457 * @udev_monitor: udev monitor
459 * Take a reference of a udev monitor.
461 * Returns: the passed udev monitor
463 _public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
465 if (udev_monitor == NULL)
467 udev_monitor->refcount++;
472 * udev_monitor_unref:
473 * @udev_monitor: udev monitor
475 * Drop a reference of a udev monitor. If the refcount reaches zero,
476 * the bound socket will be closed, and the resources of the monitor
481 _public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor)
483 if (udev_monitor == NULL)
485 udev_monitor->refcount--;
486 if (udev_monitor->refcount > 0)
488 if (udev_monitor->sock >= 0)
489 close(udev_monitor->sock);
490 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
491 udev_list_cleanup(&udev_monitor->filter_tag_list);
497 * udev_monitor_get_udev:
498 * @udev_monitor: udev monitor
500 * Retrieve the udev library context the monitor was created with.
502 * Returns: the udev library context
504 _public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
506 if (udev_monitor == NULL)
508 return udev_monitor->udev;
512 * udev_monitor_get_fd:
513 * @udev_monitor: udev monitor
515 * Retrieve the socket file descriptor associated with the monitor.
517 * Returns: the socket file descriptor
519 _public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
521 if (udev_monitor == NULL)
523 return udev_monitor->sock;
526 static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
528 struct udev_list_entry *list_entry;
530 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
532 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
533 const char *subsys = udev_list_entry_get_name(list_entry);
534 const char *dsubsys = udev_device_get_subsystem(udev_device);
536 const char *ddevtype;
538 if (!streq(dsubsys, subsys))
541 devtype = udev_list_entry_get_value(list_entry);
544 ddevtype = udev_device_get_devtype(udev_device);
545 if (ddevtype == NULL)
547 if (streq(ddevtype, devtype))
553 if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
555 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
556 const char *tag = udev_list_entry_get_name(list_entry);
558 if (udev_device_has_tag(udev_device, tag))
565 * udev_monitor_receive_device:
566 * @udev_monitor: udev monitor
568 * Receive data from the udev monitor socket, allocate a new udev
569 * device, fill in the received data, and return the device.
571 * Only socket connections with uid=0 are accepted.
573 * The monitor socket is by default set to NONBLOCK. A variant of poll() on
574 * the file descriptor returned by udev_monitor_get_fd() should to be used to
575 * wake up when new devices arrive, or alternatively the file descriptor
576 * switched into blocking mode.
578 * The initial refcount is 1, and needs to be decremented to
579 * release the resources of the udev device.
581 * Returns: a new udev device, or #NULL, in case of an error
583 _public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
585 struct udev_device *udev_device;
588 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
589 struct cmsghdr *cmsg;
590 union sockaddr_union snl;
597 if (udev_monitor == NULL)
600 iov.iov_len = sizeof(buf);
601 memset (&smsg, 0x00, sizeof(struct msghdr));
604 smsg.msg_control = cred_msg;
605 smsg.msg_controllen = sizeof(cred_msg);
606 smsg.msg_name = &snl;
607 smsg.msg_namelen = sizeof(snl);
609 buflen = recvmsg(udev_monitor->sock, &smsg, 0);
612 udev_dbg(udev_monitor->udev, "unable to receive message\n");
616 if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
617 udev_dbg(udev_monitor->udev, "invalid message length\n");
621 if (snl.nl.nl_groups == 0) {
622 /* unicast message, check if we trust the sender */
623 if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 ||
624 snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) {
625 udev_dbg(udev_monitor->udev, "unicast netlink message ignored\n");
628 } else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) {
629 if (snl.nl.nl_pid > 0) {
630 udev_dbg(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n",
636 cmsg = CMSG_FIRSTHDR(&smsg);
637 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
638 udev_dbg(udev_monitor->udev, "no sender credentials received, message ignored\n");
642 cred = (struct ucred *)CMSG_DATA(cmsg);
643 if (cred->uid != 0) {
644 udev_dbg(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
648 udev_device = udev_device_new(udev_monitor->udev);
649 if (udev_device == NULL)
652 if (memcmp(buf, "libudev", 8) == 0) {
653 struct udev_monitor_netlink_header *nlh;
655 /* udev message needs proper version magic */
656 nlh = (struct udev_monitor_netlink_header *) buf;
657 if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) {
658 udev_err(udev_monitor->udev, "unrecognized message signature (%x != %x)\n",
659 nlh->magic, htonl(UDEV_MONITOR_MAGIC));
660 udev_device_unref(udev_device);
663 if (nlh->properties_off+32 > (size_t)buflen) {
664 udev_device_unref(udev_device);
668 bufpos = nlh->properties_off;
670 /* devices received from udev are always initialized */
671 udev_device_set_is_initialized(udev_device);
673 /* kernel message with header */
674 bufpos = strlen(buf) + 1;
675 if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
676 udev_dbg(udev_monitor->udev, "invalid message length\n");
677 udev_device_unref(udev_device);
681 /* check message header */
682 if (strstr(buf, "@/") == NULL) {
683 udev_dbg(udev_monitor->udev, "unrecognized message header\n");
684 udev_device_unref(udev_device);
689 udev_device_set_info_loaded(udev_device);
691 while (bufpos < buflen) {
696 keylen = strlen(key);
699 bufpos += keylen + 1;
700 udev_device_add_property_from_string_parse(udev_device, key);
703 if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) {
704 udev_dbg(udev_monitor->udev, "missing values, invalid device\n");
705 udev_device_unref(udev_device);
709 /* skip device, if it does not pass the current filter */
710 if (!passes_filter(udev_monitor, udev_device)) {
711 struct pollfd pfd[1];
714 udev_device_unref(udev_device);
716 /* if something is queued, get next device */
717 pfd[0].fd = udev_monitor->sock;
718 pfd[0].events = POLLIN;
719 rc = poll(pfd, 1, 0);
728 int udev_monitor_send_device(struct udev_monitor *udev_monitor,
729 struct udev_monitor *destination, struct udev_device *udev_device)
737 struct udev_monitor_netlink_header nlh;
738 struct udev_list_entry *list_entry;
739 uint64_t tag_bloom_bits;
741 blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
745 /* add versioned header */
746 memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header));
747 memcpy(nlh.prefix, "libudev", 8);
748 nlh.magic = htonl(UDEV_MONITOR_MAGIC);
749 nlh.header_size = sizeof(struct udev_monitor_netlink_header);
750 val = udev_device_get_subsystem(udev_device);
751 nlh.filter_subsystem_hash = htonl(util_string_hash32(val));
752 val = udev_device_get_devtype(udev_device);
754 nlh.filter_devtype_hash = htonl(util_string_hash32(val));
755 iov[0].iov_base = &nlh;
756 iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
758 /* add tag bloom filter */
760 udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
761 tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry));
762 if (tag_bloom_bits > 0) {
763 nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32);
764 nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff);
767 /* add properties list */
768 nlh.properties_off = iov[0].iov_len;
769 nlh.properties_len = blen;
770 iov[1].iov_base = (char *)buf;
771 iov[1].iov_len = blen;
773 memset(&smsg, 0x00, sizeof(struct msghdr));
777 * Use custom address for target, or the default one.
779 * If we send to a multicast group, we will get
780 * ECONNREFUSED, which is expected.
782 if (destination != NULL)
783 smsg.msg_name = &destination->snl;
785 smsg.msg_name = &udev_monitor->snl_destination;
786 smsg.msg_namelen = sizeof(struct sockaddr_nl);
787 count = sendmsg(udev_monitor->sock, &smsg, 0);
788 udev_dbg(udev_monitor->udev, "passed %zi bytes to netlink monitor %p\n", count, udev_monitor);
793 * udev_monitor_filter_add_match_subsystem_devtype:
794 * @udev_monitor: the monitor
795 * @subsystem: the subsystem value to match the incoming devices against
796 * @devtype: the devtype value to match the incoming devices against
798 * This filter is efficiently executed inside the kernel, and libudev subscribers
799 * will usually not be woken up for devices which do not match.
801 * The filter must be installed before the monitor is switched to listening mode.
803 * Returns: 0 on success, otherwise a negative error value.
805 _public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
807 if (udev_monitor == NULL)
809 if (subsystem == NULL)
811 if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL)
817 * udev_monitor_filter_add_match_tag:
818 * @udev_monitor: the monitor
819 * @tag: the name of a tag
821 * This filter is efficiently executed inside the kernel, and libudev subscribers
822 * will usually not be woken up for devices which do not match.
824 * The filter must be installed before the monitor is switched to listening mode.
826 * Returns: 0 on success, otherwise a negative error value.
828 _public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
830 if (udev_monitor == NULL)
834 if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL)
840 * udev_monitor_filter_remove:
841 * @udev_monitor: monitor
843 * Remove all filters from monitor.
845 * Returns: 0 on success, otherwise a negative error value.
847 _public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
849 static struct sock_fprog filter = { 0, NULL };
851 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
852 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));