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 union file_handle_union h = { .handle.handle_bytes = MAX_HANDLE_SZ, };
113 _cleanup_fclose_ FILE *f = NULL;
114 char line[LINE_MAX], *e;
117 r = name_to_handle_at(AT_FDCWD, "/dev", &h.handle, &mount_id, 0);
122 f = fopen("/proc/self/mountinfo", "re");
126 FOREACH_LINE(line, f, return false) {
129 if (sscanf(line, "%i", &mid) != 1)
135 e = strstr(line, " - ");
139 /* accept any name that starts with the currently expected type */
140 if (startswith(e + 3, "devtmpfs"))
147 struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd)
149 struct udev_monitor *udev_monitor;
156 group = UDEV_MONITOR_NONE;
157 else if (streq(name, "udev")) {
159 * We do not support subscribing to uevents if no instance of
160 * udev is running. Uevents would otherwise broadcast the
161 * processing data of the host into containers, which is not
164 * Containers will currently not get any udev uevents, until
165 * a supporting infrastructure is available.
167 * We do not set a netlink multicast group here, so the socket
168 * will not receive any messages.
170 if (access("/run/udev/control", F_OK) < 0 && !udev_has_devtmpfs(udev)) {
171 udev_dbg(udev, "the udev service seems not to be active, disable the monitor\n");
172 group = UDEV_MONITOR_NONE;
174 group = UDEV_MONITOR_UDEV;
175 } else if (streq(name, "kernel"))
176 group = UDEV_MONITOR_KERNEL;
180 udev_monitor = udev_monitor_new(udev);
181 if (udev_monitor == NULL)
185 udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
186 if (udev_monitor->sock == -1) {
187 udev_err(udev, "error getting socket: %m\n");
192 udev_monitor->bound = true;
193 udev_monitor->sock = fd;
196 udev_monitor->snl.nl.nl_family = AF_NETLINK;
197 udev_monitor->snl.nl.nl_groups = group;
199 /* default destination for sending */
200 udev_monitor->snl_destination.nl.nl_family = AF_NETLINK;
201 udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV;
207 * udev_monitor_new_from_netlink:
208 * @udev: udev library context
209 * @name: name of event source
211 * Create new udev monitor and connect to a specified event
212 * source. Valid sources identifiers are "udev" and "kernel".
214 * Applications should usually not connect directly to the
215 * "kernel" events, because the devices might not be useable
216 * at that time, before udev has configured them, and created
217 * device nodes. Accessing devices at the same time as udev,
218 * might result in unpredictable behavior. The "udev" events
219 * are sent out after udev has finished its event processing,
220 * all rules have been processed, and needed device nodes are
223 * The initial refcount is 1, and needs to be decremented to
224 * release the resources of the udev monitor.
226 * Returns: a new udev monitor, or #NULL, in case of an error
228 _public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
230 return udev_monitor_new_from_netlink_fd(udev, name, -1);
233 static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
234 unsigned short code, unsigned int data)
236 struct sock_filter *ins = &inss[*i];
243 static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
244 unsigned short code, unsigned int data,
245 unsigned short jt, unsigned short jf)
247 struct sock_filter *ins = &inss[*i];
257 * udev_monitor_filter_update:
258 * @udev_monitor: monitor
260 * Update the installed socket filter. This is only needed,
261 * if the filter was removed or changed.
263 * Returns: 0 on success, otherwise a negative error value.
265 _public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
267 struct sock_filter ins[512];
268 struct sock_fprog filter;
270 struct udev_list_entry *list_entry;
273 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL &&
274 udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
277 memzero(ins, sizeof(ins));
280 /* load magic in A */
281 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
282 /* jump if magic matches */
283 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
284 /* wrong magic, pass packet */
285 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
287 if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) {
290 /* count tag matches, to calculate end of tag match block */
292 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list))
295 /* add all tags matches */
296 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
297 uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry));
298 uint32_t tag_bloom_hi = tag_bloom_bits >> 32;
299 uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff;
301 /* load device bloom bits in A */
302 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi));
303 /* clear bits (tag bits & bloom bits) */
304 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi);
305 /* jump to next tag if it does not match */
306 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3);
308 /* load device bloom bits in A */
309 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo));
310 /* clear bits (tag bits & bloom bits) */
311 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo);
312 /* jump behind end of tag match block if tag matches */
314 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0);
317 /* nothing matched, drop packet */
318 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
321 /* add all subsystem matches */
322 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) {
323 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
324 unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry));
326 /* load device subsystem value in A */
327 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash));
328 if (udev_list_entry_get_value(list_entry) == NULL) {
329 /* jump if subsystem does not match */
330 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
332 /* jump if subsystem does not match */
333 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
335 /* load device devtype value in A */
336 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash));
337 /* jump if value does not match */
338 hash = util_string_hash32(udev_list_entry_get_value(list_entry));
339 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
342 /* matched, pass packet */
343 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
345 if (i+1 >= ELEMENTSOF(ins))
349 /* nothing matched, drop packet */
350 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
353 /* matched, pass packet */
354 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
357 memzero(&filter, sizeof(filter));
360 err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
361 return err < 0 ? -errno : 0;
364 int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
366 udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid;
370 * udev_monitor_enable_receiving:
371 * @udev_monitor: the monitor which should receive events
373 * Binds the @udev_monitor socket to the event source.
375 * Returns: 0 on success, otherwise a negative error value.
377 _public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
382 udev_monitor_filter_update(udev_monitor);
384 if (!udev_monitor->bound) {
385 err = bind(udev_monitor->sock,
386 &udev_monitor->snl.sa, sizeof(struct sockaddr_nl));
388 udev_monitor->bound = true;
392 union sockaddr_union snl;
396 * get the address the kernel has assigned us
397 * it is usually, but not necessarily the pid
399 addrlen = sizeof(struct sockaddr_nl);
400 err = getsockname(udev_monitor->sock, &snl.sa, &addrlen);
402 udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid;
404 udev_err(udev_monitor->udev, "bind failed: %m\n");
408 /* enable receiving of sender credentials */
409 setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
414 * udev_monitor_set_receive_buffer_size:
415 * @udev_monitor: the monitor which should receive events
416 * @size: the size in bytes
418 * Set the size of the kernel socket buffer. This call needs the
419 * appropriate privileges to succeed.
421 * Returns: 0 on success, otherwise -1 on error.
423 _public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
425 if (udev_monitor == NULL)
427 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
430 int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
434 err = close(udev_monitor->sock);
435 udev_monitor->sock = -1;
436 return err < 0 ? -errno : 0;
441 * @udev_monitor: udev monitor
443 * Take a reference of a udev monitor.
445 * Returns: the passed udev monitor
447 _public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
449 if (udev_monitor == NULL)
451 udev_monitor->refcount++;
456 * udev_monitor_unref:
457 * @udev_monitor: udev monitor
459 * Drop a reference of a udev monitor. If the refcount reaches zero,
460 * the bound socket will be closed, and the resources of the monitor
465 _public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor)
467 if (udev_monitor == NULL)
469 udev_monitor->refcount--;
470 if (udev_monitor->refcount > 0)
472 if (udev_monitor->sock >= 0)
473 close(udev_monitor->sock);
474 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
475 udev_list_cleanup(&udev_monitor->filter_tag_list);
481 * udev_monitor_get_udev:
482 * @udev_monitor: udev monitor
484 * Retrieve the udev library context the monitor was created with.
486 * Returns: the udev library context
488 _public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
490 if (udev_monitor == NULL)
492 return udev_monitor->udev;
496 * udev_monitor_get_fd:
497 * @udev_monitor: udev monitor
499 * Retrieve the socket file descriptor associated with the monitor.
501 * Returns: the socket file descriptor
503 _public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
505 if (udev_monitor == NULL)
507 return udev_monitor->sock;
510 static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
512 struct udev_list_entry *list_entry;
514 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
516 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
517 const char *subsys = udev_list_entry_get_name(list_entry);
518 const char *dsubsys = udev_device_get_subsystem(udev_device);
520 const char *ddevtype;
522 if (!streq(dsubsys, subsys))
525 devtype = udev_list_entry_get_value(list_entry);
528 ddevtype = udev_device_get_devtype(udev_device);
529 if (ddevtype == NULL)
531 if (streq(ddevtype, devtype))
537 if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
539 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
540 const char *tag = udev_list_entry_get_name(list_entry);
542 if (udev_device_has_tag(udev_device, tag))
549 * udev_monitor_receive_device:
550 * @udev_monitor: udev monitor
552 * Receive data from the udev monitor socket, allocate a new udev
553 * device, fill in the received data, and return the device.
555 * Only socket connections with uid=0 are accepted.
557 * The monitor socket is by default set to NONBLOCK. A variant of poll() on
558 * the file descriptor returned by udev_monitor_get_fd() should to be used to
559 * wake up when new devices arrive, or alternatively the file descriptor
560 * switched into blocking mode.
562 * The initial refcount is 1, and needs to be decremented to
563 * release the resources of the udev device.
565 * Returns: a new udev device, or #NULL, in case of an error
567 _public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
569 struct udev_device *udev_device;
572 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
573 struct cmsghdr *cmsg;
574 union sockaddr_union snl;
581 if (udev_monitor == NULL)
584 iov.iov_len = sizeof(buf);
585 memzero(&smsg, sizeof(struct msghdr));
588 smsg.msg_control = cred_msg;
589 smsg.msg_controllen = sizeof(cred_msg);
590 smsg.msg_name = &snl;
591 smsg.msg_namelen = sizeof(snl);
593 buflen = recvmsg(udev_monitor->sock, &smsg, 0);
596 udev_dbg(udev_monitor->udev, "unable to receive message\n");
600 if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
601 udev_dbg(udev_monitor->udev, "invalid message length\n");
605 if (snl.nl.nl_groups == 0) {
606 /* unicast message, check if we trust the sender */
607 if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 ||
608 snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) {
609 udev_dbg(udev_monitor->udev, "unicast netlink message ignored\n");
612 } else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) {
613 if (snl.nl.nl_pid > 0) {
614 udev_dbg(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n",
620 cmsg = CMSG_FIRSTHDR(&smsg);
621 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
622 udev_dbg(udev_monitor->udev, "no sender credentials received, message ignored\n");
626 cred = (struct ucred *)CMSG_DATA(cmsg);
627 if (cred->uid != 0) {
628 udev_dbg(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
632 udev_device = udev_device_new(udev_monitor->udev);
633 if (udev_device == NULL)
636 if (memcmp(buf, "libudev", 8) == 0) {
637 struct udev_monitor_netlink_header *nlh;
639 /* udev message needs proper version magic */
640 nlh = (struct udev_monitor_netlink_header *) buf;
641 if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) {
642 udev_err(udev_monitor->udev, "unrecognized message signature (%x != %x)\n",
643 nlh->magic, htonl(UDEV_MONITOR_MAGIC));
644 udev_device_unref(udev_device);
647 if (nlh->properties_off+32 > (size_t)buflen) {
648 udev_device_unref(udev_device);
652 bufpos = nlh->properties_off;
654 /* devices received from udev are always initialized */
655 udev_device_set_is_initialized(udev_device);
657 /* kernel message with header */
658 bufpos = strlen(buf) + 1;
659 if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
660 udev_dbg(udev_monitor->udev, "invalid message length\n");
661 udev_device_unref(udev_device);
665 /* check message header */
666 if (strstr(buf, "@/") == NULL) {
667 udev_dbg(udev_monitor->udev, "unrecognized message header\n");
668 udev_device_unref(udev_device);
673 udev_device_set_info_loaded(udev_device);
675 while (bufpos < buflen) {
680 keylen = strlen(key);
683 bufpos += keylen + 1;
684 udev_device_add_property_from_string_parse(udev_device, key);
687 if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) {
688 udev_dbg(udev_monitor->udev, "missing values, invalid device\n");
689 udev_device_unref(udev_device);
693 /* skip device, if it does not pass the current filter */
694 if (!passes_filter(udev_monitor, udev_device)) {
695 struct pollfd pfd[1];
698 udev_device_unref(udev_device);
700 /* if something is queued, get next device */
701 pfd[0].fd = udev_monitor->sock;
702 pfd[0].events = POLLIN;
703 rc = poll(pfd, 1, 0);
712 int udev_monitor_send_device(struct udev_monitor *udev_monitor,
713 struct udev_monitor *destination, struct udev_device *udev_device)
721 struct udev_monitor_netlink_header nlh;
722 struct udev_list_entry *list_entry;
723 uint64_t tag_bloom_bits;
725 blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
729 /* add versioned header */
730 memzero(&nlh, sizeof(struct udev_monitor_netlink_header));
731 memcpy(nlh.prefix, "libudev", 8);
732 nlh.magic = htonl(UDEV_MONITOR_MAGIC);
733 nlh.header_size = sizeof(struct udev_monitor_netlink_header);
734 val = udev_device_get_subsystem(udev_device);
735 nlh.filter_subsystem_hash = htonl(util_string_hash32(val));
736 val = udev_device_get_devtype(udev_device);
738 nlh.filter_devtype_hash = htonl(util_string_hash32(val));
739 iov[0].iov_base = &nlh;
740 iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
742 /* add tag bloom filter */
744 udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
745 tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry));
746 if (tag_bloom_bits > 0) {
747 nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32);
748 nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff);
751 /* add properties list */
752 nlh.properties_off = iov[0].iov_len;
753 nlh.properties_len = blen;
754 iov[1].iov_base = (char *)buf;
755 iov[1].iov_len = blen;
757 memzero(&smsg, sizeof(struct msghdr));
761 * Use custom address for target, or the default one.
763 * If we send to a multicast group, we will get
764 * ECONNREFUSED, which is expected.
766 if (destination != NULL)
767 smsg.msg_name = &destination->snl;
769 smsg.msg_name = &udev_monitor->snl_destination;
770 smsg.msg_namelen = sizeof(struct sockaddr_nl);
771 count = sendmsg(udev_monitor->sock, &smsg, 0);
772 udev_dbg(udev_monitor->udev, "passed %zi bytes to netlink monitor %p\n", count, udev_monitor);
777 * udev_monitor_filter_add_match_subsystem_devtype:
778 * @udev_monitor: the monitor
779 * @subsystem: the subsystem value to match the incoming devices against
780 * @devtype: the devtype value to match the incoming devices against
782 * This filter is efficiently executed inside the kernel, and libudev subscribers
783 * will usually not be woken up for devices which do not match.
785 * The filter must be installed before the monitor is switched to listening mode.
787 * Returns: 0 on success, otherwise a negative error value.
789 _public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
791 if (udev_monitor == NULL)
793 if (subsystem == NULL)
795 if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL)
801 * udev_monitor_filter_add_match_tag:
802 * @udev_monitor: the monitor
803 * @tag: the name of a tag
805 * This filter is efficiently executed inside the kernel, and libudev subscribers
806 * will usually not be woken up for devices which do not match.
808 * The filter must be installed before the monitor is switched to listening mode.
810 * Returns: 0 on success, otherwise a negative error value.
812 _public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
814 if (udev_monitor == NULL)
818 if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL)
824 * udev_monitor_filter_remove:
825 * @udev_monitor: monitor
827 * Remove all filters from monitor.
829 * Returns: 0 on success, otherwise a negative error value.
831 _public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
833 static struct sock_fprog filter = { 0, NULL };
835 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
836 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));