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
));