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 = new0(struct udev_monitor, 1);
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);
118 h->handle_bytes = 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) {
131 if (sscanf(line, "%i", &mid) != 1)
137 e = strstr(line, " - ");
141 /* accept any name that starts with the currently expected type */
142 if (startswith(e + 3, "devtmpfs"))
149 /* we consider udev running when we have running udev service */
150 static bool udev_has_service(struct udev *udev) {
151 struct udev_queue *queue;
154 queue = udev_queue_new(udev);
158 active = udev_queue_get_udev_is_active(queue);
159 udev_queue_unref(queue);
164 struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd)
166 struct udev_monitor *udev_monitor;
173 group = UDEV_MONITOR_NONE;
174 else if (streq(name, "udev")) {
176 * We do not support subscribing to uevents if no instance of
177 * udev is running. Uevents would otherwise broadcast the
178 * processing data of the host into containers, which is not
181 * Containers will currently not get any udev uevents, until
182 * a supporting infrastructure is available.
184 * We do not set a netlink multicast group here, so the socket
185 * will not receive any messages.
187 if (!udev_has_service(udev) && !udev_has_devtmpfs(udev)) {
188 udev_dbg(udev, "the udev service seems not to be active, disable the monitor\n");
189 group = UDEV_MONITOR_NONE;
191 group = UDEV_MONITOR_UDEV;
192 } else if (streq(name, "kernel"))
193 group = UDEV_MONITOR_KERNEL;
197 udev_monitor = udev_monitor_new(udev);
198 if (udev_monitor == NULL)
202 udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
203 if (udev_monitor->sock == -1) {
204 udev_err(udev, "error getting socket: %m\n");
209 udev_monitor->bound = true;
210 udev_monitor->sock = fd;
213 udev_monitor->snl.nl.nl_family = AF_NETLINK;
214 udev_monitor->snl.nl.nl_groups = group;
216 /* default destination for sending */
217 udev_monitor->snl_destination.nl.nl_family = AF_NETLINK;
218 udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV;
224 * udev_monitor_new_from_netlink:
225 * @udev: udev library context
226 * @name: name of event source
228 * Create new udev monitor and connect to a specified event
229 * source. Valid sources identifiers are "udev" and "kernel".
231 * Applications should usually not connect directly to the
232 * "kernel" events, because the devices might not be useable
233 * at that time, before udev has configured them, and created
234 * device nodes. Accessing devices at the same time as udev,
235 * might result in unpredictable behavior. The "udev" events
236 * are sent out after udev has finished its event processing,
237 * all rules have been processed, and needed device nodes are
240 * The initial refcount is 1, and needs to be decremented to
241 * release the resources of the udev monitor.
243 * Returns: a new udev monitor, or #NULL, in case of an error
245 _public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
247 return udev_monitor_new_from_netlink_fd(udev, name, -1);
250 static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
251 unsigned short code, unsigned int data)
253 struct sock_filter *ins = &inss[*i];
260 static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
261 unsigned short code, unsigned int data,
262 unsigned short jt, unsigned short jf)
264 struct sock_filter *ins = &inss[*i];
274 * udev_monitor_filter_update:
275 * @udev_monitor: monitor
277 * Update the installed socket filter. This is only needed,
278 * if the filter was removed or changed.
280 * Returns: 0 on success, otherwise a negative error value.
282 _public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
284 struct sock_filter ins[512];
285 struct sock_fprog filter;
287 struct udev_list_entry *list_entry;
290 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL &&
291 udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
294 memzero(ins, sizeof(ins));
297 /* load magic in A */
298 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
299 /* jump if magic matches */
300 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
301 /* wrong magic, pass packet */
302 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
304 if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) {
307 /* count tag matches, to calculate end of tag match block */
309 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list))
312 /* add all tags matches */
313 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
314 uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry));
315 uint32_t tag_bloom_hi = tag_bloom_bits >> 32;
316 uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff;
318 /* load device bloom bits in A */
319 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi));
320 /* clear bits (tag bits & bloom bits) */
321 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi);
322 /* jump to next tag if it does not match */
323 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3);
325 /* load device bloom bits in A */
326 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo));
327 /* clear bits (tag bits & bloom bits) */
328 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo);
329 /* jump behind end of tag match block if tag matches */
331 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0);
334 /* nothing matched, drop packet */
335 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
338 /* add all subsystem matches */
339 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) {
340 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
341 unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry));
343 /* load device subsystem value in A */
344 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash));
345 if (udev_list_entry_get_value(list_entry) == NULL) {
346 /* jump if subsystem does not match */
347 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
349 /* jump if subsystem does not match */
350 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
352 /* load device devtype value in A */
353 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash));
354 /* jump if value does not match */
355 hash = util_string_hash32(udev_list_entry_get_value(list_entry));
356 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
359 /* matched, pass packet */
360 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
362 if (i+1 >= ELEMENTSOF(ins))
366 /* nothing matched, drop packet */
367 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
370 /* matched, pass packet */
371 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
374 memzero(&filter, sizeof(filter));
377 err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
378 return err < 0 ? -errno : 0;
381 int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
383 udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid;
387 * udev_monitor_enable_receiving:
388 * @udev_monitor: the monitor which should receive events
390 * Binds the @udev_monitor socket to the event source.
392 * Returns: 0 on success, otherwise a negative error value.
394 _public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
399 udev_monitor_filter_update(udev_monitor);
401 if (!udev_monitor->bound) {
402 err = bind(udev_monitor->sock,
403 &udev_monitor->snl.sa, sizeof(struct sockaddr_nl));
405 udev_monitor->bound = true;
409 union sockaddr_union snl;
413 * get the address the kernel has assigned us
414 * it is usually, but not necessarily the pid
416 addrlen = sizeof(struct sockaddr_nl);
417 err = getsockname(udev_monitor->sock, &snl.sa, &addrlen);
419 udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid;
421 udev_err(udev_monitor->udev, "bind failed: %m\n");
425 /* enable receiving of sender credentials */
426 setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
431 * udev_monitor_set_receive_buffer_size:
432 * @udev_monitor: the monitor which should receive events
433 * @size: the size in bytes
435 * Set the size of the kernel socket buffer. This call needs the
436 * appropriate privileges to succeed.
438 * Returns: 0 on success, otherwise -1 on error.
440 _public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
442 if (udev_monitor == NULL)
444 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
447 int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
451 err = close(udev_monitor->sock);
452 udev_monitor->sock = -1;
453 return err < 0 ? -errno : 0;
458 * @udev_monitor: udev monitor
460 * Take a reference of a udev monitor.
462 * Returns: the passed udev monitor
464 _public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
466 if (udev_monitor == NULL)
468 udev_monitor->refcount++;
473 * udev_monitor_unref:
474 * @udev_monitor: udev monitor
476 * Drop a reference of a udev monitor. If the refcount reaches zero,
477 * the bound socket will be closed, and the resources of the monitor
482 _public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor)
484 if (udev_monitor == NULL)
486 udev_monitor->refcount--;
487 if (udev_monitor->refcount > 0)
489 if (udev_monitor->sock >= 0)
490 close(udev_monitor->sock);
491 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
492 udev_list_cleanup(&udev_monitor->filter_tag_list);
498 * udev_monitor_get_udev:
499 * @udev_monitor: udev monitor
501 * Retrieve the udev library context the monitor was created with.
503 * Returns: the udev library context
505 _public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
507 if (udev_monitor == NULL)
509 return udev_monitor->udev;
513 * udev_monitor_get_fd:
514 * @udev_monitor: udev monitor
516 * Retrieve the socket file descriptor associated with the monitor.
518 * Returns: the socket file descriptor
520 _public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
522 if (udev_monitor == NULL)
524 return udev_monitor->sock;
527 static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
529 struct udev_list_entry *list_entry;
531 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
533 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
534 const char *subsys = udev_list_entry_get_name(list_entry);
535 const char *dsubsys = udev_device_get_subsystem(udev_device);
537 const char *ddevtype;
539 if (!streq(dsubsys, subsys))
542 devtype = udev_list_entry_get_value(list_entry);
545 ddevtype = udev_device_get_devtype(udev_device);
546 if (ddevtype == NULL)
548 if (streq(ddevtype, devtype))
554 if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
556 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
557 const char *tag = udev_list_entry_get_name(list_entry);
559 if (udev_device_has_tag(udev_device, tag))
566 * udev_monitor_receive_device:
567 * @udev_monitor: udev monitor
569 * Receive data from the udev monitor socket, allocate a new udev
570 * device, fill in the received data, and return the device.
572 * Only socket connections with uid=0 are accepted.
574 * The monitor socket is by default set to NONBLOCK. A variant of poll() on
575 * the file descriptor returned by udev_monitor_get_fd() should to be used to
576 * wake up when new devices arrive, or alternatively the file descriptor
577 * switched into blocking mode.
579 * The initial refcount is 1, and needs to be decremented to
580 * release the resources of the udev device.
582 * Returns: a new udev device, or #NULL, in case of an error
584 _public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
586 struct udev_device *udev_device;
589 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
590 struct cmsghdr *cmsg;
591 union sockaddr_union snl;
598 if (udev_monitor == NULL)
601 iov.iov_len = sizeof(buf);
602 memzero(&smsg, sizeof(struct msghdr));
605 smsg.msg_control = cred_msg;
606 smsg.msg_controllen = sizeof(cred_msg);
607 smsg.msg_name = &snl;
608 smsg.msg_namelen = sizeof(snl);
610 buflen = recvmsg(udev_monitor->sock, &smsg, 0);
613 udev_dbg(udev_monitor->udev, "unable to receive message\n");
617 if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
618 udev_dbg(udev_monitor->udev, "invalid message length\n");
622 if (snl.nl.nl_groups == 0) {
623 /* unicast message, check if we trust the sender */
624 if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 ||
625 snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) {
626 udev_dbg(udev_monitor->udev, "unicast netlink message ignored\n");
629 } else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) {
630 if (snl.nl.nl_pid > 0) {
631 udev_dbg(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n",
637 cmsg = CMSG_FIRSTHDR(&smsg);
638 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
639 udev_dbg(udev_monitor->udev, "no sender credentials received, message ignored\n");
643 cred = (struct ucred *)CMSG_DATA(cmsg);
644 if (cred->uid != 0) {
645 udev_dbg(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
649 udev_device = udev_device_new(udev_monitor->udev);
650 if (udev_device == NULL)
653 if (memcmp(buf, "libudev", 8) == 0) {
654 struct udev_monitor_netlink_header *nlh;
656 /* udev message needs proper version magic */
657 nlh = (struct udev_monitor_netlink_header *) buf;
658 if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) {
659 udev_err(udev_monitor->udev, "unrecognized message signature (%x != %x)\n",
660 nlh->magic, htonl(UDEV_MONITOR_MAGIC));
661 udev_device_unref(udev_device);
664 if (nlh->properties_off+32 > (size_t)buflen) {
665 udev_device_unref(udev_device);
669 bufpos = nlh->properties_off;
671 /* devices received from udev are always initialized */
672 udev_device_set_is_initialized(udev_device);
674 /* kernel message with header */
675 bufpos = strlen(buf) + 1;
676 if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
677 udev_dbg(udev_monitor->udev, "invalid message length\n");
678 udev_device_unref(udev_device);
682 /* check message header */
683 if (strstr(buf, "@/") == NULL) {
684 udev_dbg(udev_monitor->udev, "unrecognized message header\n");
685 udev_device_unref(udev_device);
690 udev_device_set_info_loaded(udev_device);
692 while (bufpos < buflen) {
697 keylen = strlen(key);
700 bufpos += keylen + 1;
701 udev_device_add_property_from_string_parse(udev_device, key);
704 if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) {
705 udev_dbg(udev_monitor->udev, "missing values, invalid device\n");
706 udev_device_unref(udev_device);
710 /* skip device, if it does not pass the current filter */
711 if (!passes_filter(udev_monitor, udev_device)) {
712 struct pollfd pfd[1];
715 udev_device_unref(udev_device);
717 /* if something is queued, get next device */
718 pfd[0].fd = udev_monitor->sock;
719 pfd[0].events = POLLIN;
720 rc = poll(pfd, 1, 0);
729 int udev_monitor_send_device(struct udev_monitor *udev_monitor,
730 struct udev_monitor *destination, struct udev_device *udev_device)
738 struct udev_monitor_netlink_header nlh;
739 struct udev_list_entry *list_entry;
740 uint64_t tag_bloom_bits;
742 blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
746 /* add versioned header */
747 memzero(&nlh, sizeof(struct udev_monitor_netlink_header));
748 memcpy(nlh.prefix, "libudev", 8);
749 nlh.magic = htonl(UDEV_MONITOR_MAGIC);
750 nlh.header_size = sizeof(struct udev_monitor_netlink_header);
751 val = udev_device_get_subsystem(udev_device);
752 nlh.filter_subsystem_hash = htonl(util_string_hash32(val));
753 val = udev_device_get_devtype(udev_device);
755 nlh.filter_devtype_hash = htonl(util_string_hash32(val));
756 iov[0].iov_base = &nlh;
757 iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
759 /* add tag bloom filter */
761 udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
762 tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry));
763 if (tag_bloom_bits > 0) {
764 nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32);
765 nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff);
768 /* add properties list */
769 nlh.properties_off = iov[0].iov_len;
770 nlh.properties_len = blen;
771 iov[1].iov_base = (char *)buf;
772 iov[1].iov_len = blen;
774 memzero(&smsg, sizeof(struct msghdr));
778 * Use custom address for target, or the default one.
780 * If we send to a multicast group, we will get
781 * ECONNREFUSED, which is expected.
783 if (destination != NULL)
784 smsg.msg_name = &destination->snl;
786 smsg.msg_name = &udev_monitor->snl_destination;
787 smsg.msg_namelen = sizeof(struct sockaddr_nl);
788 count = sendmsg(udev_monitor->sock, &smsg, 0);
789 udev_dbg(udev_monitor->udev, "passed %zi bytes to netlink monitor %p\n", count, udev_monitor);
794 * udev_monitor_filter_add_match_subsystem_devtype:
795 * @udev_monitor: the monitor
796 * @subsystem: the subsystem value to match the incoming devices against
797 * @devtype: the devtype value to match the incoming devices against
799 * This filter is efficiently executed inside the kernel, and libudev subscribers
800 * will usually not be woken up for devices which do not match.
802 * The filter must be installed before the monitor is switched to listening mode.
804 * Returns: 0 on success, otherwise a negative error value.
806 _public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
808 if (udev_monitor == NULL)
810 if (subsystem == NULL)
812 if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL)
818 * udev_monitor_filter_add_match_tag:
819 * @udev_monitor: the monitor
820 * @tag: the name of a tag
822 * This filter is efficiently executed inside the kernel, and libudev subscribers
823 * will usually not be woken up for devices which do not match.
825 * The filter must be installed before the monitor is switched to listening mode.
827 * Returns: 0 on success, otherwise a negative error value.
829 _public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
831 if (udev_monitor == NULL)
835 if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL)
841 * udev_monitor_filter_remove:
842 * @udev_monitor: monitor
844 * Remove all filters from monitor.
846 * Returns: 0 on success, otherwise a negative error value.
848 _public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
850 static struct sock_fprog filter = { 0, NULL };
852 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
853 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));