2 * libudev - interface to udev device information
4 * Copyright (C) 2008-2009 Kay Sievers <kay.sievers@vrfy.org>
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
21 #include <sys/socket.h>
23 #include <arpa/inet.h>
24 #include <linux/netlink.h>
25 #include <linux/filter.h>
28 #include "libudev-private.h"
31 * SECTION:libudev-monitor
32 * @short_description: device event source
34 * Connects to a device event source.
41 * Opaque object handling one event source.
47 struct sockaddr_nl snl;
48 struct sockaddr_nl snl_trusted_sender;
49 struct sockaddr_nl snl_destination;
50 struct sockaddr_un sun;
52 struct udev_list_node filter_subsystem_list;
55 enum udev_monitor_netlink_group {
61 #define UDEV_MONITOR_MAGIC 0xcafe1dea
62 struct udev_monitor_netlink_header {
63 /* udev version text */
66 * magic to protect against daemon <-> library message format mismatch
67 * used in the kernel from socket filter rules; needs to be stored in network order
70 /* properties buffer */
71 unsigned short properties_off;
72 unsigned short properties_len;
74 * hashes of some common device properties strings to filter with socket filters in
75 * the client used in the kernel from socket filter rules; needs to be stored in
78 unsigned int filter_subsystem;
79 unsigned int filter_devtype;
82 static struct udev_monitor *udev_monitor_new(struct udev *udev)
84 struct udev_monitor *udev_monitor;
86 udev_monitor = calloc(1, sizeof(struct udev_monitor));
87 if (udev_monitor == NULL)
89 udev_monitor->refcount = 1;
90 udev_monitor->udev = udev;
91 udev_list_init(&udev_monitor->filter_subsystem_list);
96 * udev_monitor_new_from_socket:
97 * @udev: udev library context
98 * @socket_path: unix socket path
100 * Create new udev monitor and connect to a specified socket. The
101 * path to a socket either points to an existing socket file, or if
102 * the socket path starts with a '@' character, an abstract namespace
103 * socket will be used.
105 * A socket file will not be created. If it does not already exist,
106 * it will fall-back and connect to an abstract namespace socket with
107 * the given path. The permissions adjustment of a socket file, as
108 * well as the later cleanup, needs to be done by the caller.
110 * The initial refcount is 1, and needs to be decremented to
111 * release the resources of the udev monitor.
113 * Returns: a new udev monitor, or #NULL, in case of an error
115 struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
117 struct udev_monitor *udev_monitor;
122 if (socket_path == NULL)
124 udev_monitor = udev_monitor_new(udev);
125 if (udev_monitor == NULL)
128 udev_monitor->sun.sun_family = AF_LOCAL;
129 if (socket_path[0] == '@') {
130 /* translate leading '@' to abstract namespace */
131 util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
132 udev_monitor->sun.sun_path[0] = '\0';
133 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
134 } else if (stat(socket_path, &statbuf) == 0 && S_ISSOCK(statbuf.st_mode)) {
135 /* existing socket file */
136 util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
137 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
139 /* no socket file, assume abstract namespace socket */
140 util_strscpy(&udev_monitor->sun.sun_path[1], sizeof(udev_monitor->sun.sun_path)-1, socket_path);
141 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path)+1;
143 udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
144 if (udev_monitor->sock == -1) {
145 err(udev, "error getting socket: %m\n");
149 util_set_fd_cloexec(udev_monitor->sock);
151 dbg(udev, "monitor %p created with '%s'\n", udev_monitor, socket_path);
156 * udev_monitor_new_from_netlink:
157 * @udev: udev library context
158 * @name: name of event source
160 * Create new udev monitor and connect to a specified event
161 * source. Valid sources identifiers are "udev" and "kernel".
163 * Applications should usually not connect directly to the
164 * "kernel" events, because the devices might not be useable
165 * at that time, before udev has configured them, and created
168 * Accessing devices at the same time as udev, might result
169 * in unpredictable behavior.
171 * The "udev" events are sent out after udev has finished its
172 * event processing, all rules have been processed, and needed
173 * device nodes are created.
175 * The initial refcount is 1, and needs to be decremented to
176 * release the resources of the udev monitor.
178 * Returns: a new udev monitor, or #NULL, in case of an error
180 struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
182 struct udev_monitor *udev_monitor;
189 group = UDEV_MONITOR_NONE;
190 else if (strcmp(name, "udev") == 0)
191 group = UDEV_MONITOR_UDEV;
192 else if (strcmp(name, "kernel") == 0)
193 group = UDEV_MONITOR_KERNEL;
197 udev_monitor = udev_monitor_new(udev);
198 if (udev_monitor == NULL)
201 udev_monitor->sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
202 if (udev_monitor->sock == -1) {
203 err(udev, "error getting socket: %m\n");
207 util_set_fd_cloexec(udev_monitor->sock);
209 udev_monitor->snl.nl_family = AF_NETLINK;
210 udev_monitor->snl.nl_groups = group;
212 /* default destination for sending */
213 udev_monitor->snl_destination.nl_family = AF_NETLINK;
214 udev_monitor->snl_destination.nl_groups = UDEV_MONITOR_UDEV;
216 dbg(udev, "monitor %p created with NETLINK_KOBJECT_UEVENT (%u)\n", udev_monitor, group);
220 static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
221 unsigned short code, unsigned int data)
223 struct sock_filter *ins = &inss[*i];
230 static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
231 unsigned short code, unsigned int data,
232 unsigned short jt, unsigned short jf)
234 struct sock_filter *ins = &inss[*i];
244 * udev_monitor_filter_update:
245 * @udev_monitor: monitor
247 * Update the installed filter. This might only be needed, if the filter was removed or changed.
249 * Returns: 0 on success, otherwise a negative error value.
251 int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
253 static struct sock_filter ins[256];
254 static struct sock_fprog filter;
256 struct udev_list_entry *list_entry;
259 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
262 memset(ins, 0x00, sizeof(ins));
265 /* load magic in A */
266 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
267 /* jump if magic matches */
268 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
269 /* wrong magic, pass packet */
270 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
272 /* add all subsystem match values */
273 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
276 /* load filter_subsystem value in A */
277 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem));
278 hash = util_string_hash32(udev_list_entry_get_name(list_entry));
279 if (udev_list_entry_get_value(list_entry) == NULL) {
280 /* jump if subsystem does not match */
281 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
283 /* jump if subsystem does not match */
284 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
286 /* load filter_devtype value in A */
287 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype));
288 /* jump if value does not match */
289 hash = util_string_hash32(udev_list_entry_get_value(list_entry));
290 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
293 /* matched, pass packet */
294 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
296 if (i+1 >= ARRAY_SIZE(ins))
299 /* nothing matched, drop packet */
300 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
305 err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
309 int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
311 udev_monitor->snl_trusted_sender.nl_pid = sender->snl.nl_pid;
315 * udev_monitor_enable_receiving:
316 * @udev_monitor: the monitor which should receive events
318 * Binds the @udev_monitor socket to the event source.
320 * Returns: 0 on success, otherwise a negative error value.
322 int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
327 if (udev_monitor->sun.sun_family != 0) {
328 err = bind(udev_monitor->sock,
329 (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
330 } else if (udev_monitor->snl.nl_family != 0) {
331 udev_monitor_filter_update(udev_monitor);
332 err = bind(udev_monitor->sock,
333 (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
335 struct sockaddr_nl snl;
339 * get the address the kernel has assigned us
340 * it is usually, but not neccessarily the pid
342 addrlen = sizeof(struct sockaddr_nl);
343 err = getsockname(udev_monitor->sock, (struct sockaddr *)&snl, &addrlen);
345 udev_monitor->snl.nl_pid = snl.nl_pid;
352 err(udev_monitor->udev, "bind failed: %m\n");
356 /* enable receiving of sender credentials */
357 setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
361 int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
363 if (udev_monitor == NULL)
365 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
368 int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
372 err = close(udev_monitor->sock);
373 udev_monitor->sock = -1;
379 * @udev_monitor: udev monitor
381 * Take a reference of a udev monitor.
383 * Returns: the passed udev monitor
385 struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
387 if (udev_monitor == NULL)
389 udev_monitor->refcount++;
394 * udev_monitor_unref:
395 * @udev_monitor: udev monitor
397 * Drop a reference of a udev monitor. If the refcount reaches zero,
398 * the bound socket will be closed, and the resources of the monitor
402 void udev_monitor_unref(struct udev_monitor *udev_monitor)
404 if (udev_monitor == NULL)
406 udev_monitor->refcount--;
407 if (udev_monitor->refcount > 0)
409 if (udev_monitor->sock >= 0)
410 close(udev_monitor->sock);
411 udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_subsystem_list);
412 dbg(udev_monitor->udev, "monitor %p released\n", udev_monitor);
417 * udev_monitor_get_udev:
418 * @udev_monitor: udev monitor
420 * Retrieve the udev library context the monitor was created with.
422 * Returns: the udev library context
424 struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
426 if (udev_monitor == NULL)
428 return udev_monitor->udev;
432 * udev_monitor_get_fd:
433 * @udev_monitor: udev monitor
435 * Retrieve the socket file descriptor associated with the monitor.
437 * Returns: the socket file descriptor
439 int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
441 if (udev_monitor == NULL)
443 return udev_monitor->sock;
446 static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
448 struct udev_list_entry *list_entry;
450 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
453 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
454 const char *subsys = udev_list_entry_get_name(list_entry);
455 const char *dsubsys = udev_device_get_subsystem(udev_device);
457 const char *ddevtype;
459 if (strcmp(dsubsys, subsys) != 0)
462 devtype = udev_list_entry_get_value(list_entry);
465 ddevtype = udev_device_get_devtype(udev_device);
466 if (ddevtype == NULL)
468 if (strcmp(ddevtype, devtype) == 0)
475 * udev_monitor_receive_device:
476 * @udev_monitor: udev monitor
478 * Receive data from the udev monitor socket, allocate a new udev
479 * device, fill in the received data, and return the device.
481 * Only socket connections with uid=0 are accepted. The caller
482 * needs to make sure that there is data to read from the socket.
483 * The call will block until the socket becomes readable.
485 * The initial refcount is 1, and needs to be decremented to
486 * release the resources of the udev device.
488 * Returns: a new udev device, or #NULL, in case of an error
490 struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
492 struct udev_device *udev_device;
495 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
496 struct cmsghdr *cmsg;
497 struct sockaddr_nl snl;
502 struct udev_monitor_netlink_header *nlh;
504 int subsystem_set = 0;
511 if (udev_monitor == NULL)
513 memset(buf, 0x00, sizeof(buf));
515 iov.iov_len = sizeof(buf);
516 memset (&smsg, 0x00, sizeof(struct msghdr));
519 smsg.msg_control = cred_msg;
520 smsg.msg_controllen = sizeof(cred_msg);
522 if (udev_monitor->snl.nl_family != 0) {
523 smsg.msg_name = &snl;
524 smsg.msg_namelen = sizeof(snl);
527 buflen = recvmsg(udev_monitor->sock, &smsg, 0);
530 info(udev_monitor->udev, "unable to receive message\n");
534 if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
535 info(udev_monitor->udev, "invalid message length\n");
539 if (udev_monitor->snl.nl_family != 0) {
540 if (snl.nl_groups == 0) {
541 /* unicast message, check if we trust the sender */
542 if (udev_monitor->snl_trusted_sender.nl_pid == 0 ||
543 snl.nl_pid != udev_monitor->snl_trusted_sender.nl_pid) {
544 info(udev_monitor->udev, "unicast netlink message ignored\n");
547 } else if (snl.nl_groups == UDEV_MONITOR_KERNEL) {
548 if (snl.nl_pid > 0) {
549 info(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n", snl.nl_pid);
556 cmsg = CMSG_FIRSTHDR(&smsg);
557 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
558 info(udev_monitor->udev, "no sender credentials received, message ignored\n");
562 cred = (struct ucred *)CMSG_DATA(cmsg);
563 if (cred->uid != 0) {
564 info(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
568 if (strncmp(buf, "udev-", 5) == 0) {
569 /* udev message needs proper version magic */
570 nlh = (struct udev_monitor_netlink_header *) buf;
571 if (nlh->magic != htonl(UDEV_MONITOR_MAGIC))
573 if (nlh->properties_off < sizeof(struct udev_monitor_netlink_header))
575 if (nlh->properties_off+32 > buflen)
577 bufpos = nlh->properties_off;
579 /* kernel message with header */
580 bufpos = strlen(buf) + 1;
581 if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
582 info(udev_monitor->udev, "invalid message length\n");
586 /* check message header */
587 if (strstr(buf, "@/") == NULL) {
588 info(udev_monitor->udev, "unrecognized message header\n");
593 udev_device = udev_device_new(udev_monitor->udev);
594 if (udev_device == NULL) {
598 while (bufpos < buflen) {
603 keylen = strlen(key);
606 bufpos += keylen + 1;
608 if (strncmp(key, "DEVPATH=", 8) == 0) {
609 char path[UTIL_PATH_SIZE];
611 util_strscpyl(path, sizeof(path), udev_get_sys_path(udev_monitor->udev), &key[8], NULL);
612 udev_device_set_syspath(udev_device, path);
614 } else if (strncmp(key, "SUBSYSTEM=", 10) == 0) {
615 udev_device_set_subsystem(udev_device, &key[10]);
617 } else if (strncmp(key, "DEVTYPE=", 8) == 0) {
618 udev_device_set_devtype(udev_device, &key[8]);
619 } else if (strncmp(key, "DEVNAME=", 8) == 0) {
621 udev_device_set_knodename(udev_device, &key[8]);
623 udev_device_set_devnode(udev_device, &key[8]);
624 } else if (strncmp(key, "DEVLINKS=", 9) == 0) {
625 char devlinks[UTIL_PATH_SIZE];
629 util_strscpy(devlinks, sizeof(devlinks), &key[9]);
631 next = strchr(slink, ' ');
632 while (next != NULL) {
634 udev_device_add_devlink(udev_device, slink);
636 next = strchr(slink, ' ');
638 if (slink[0] != '\0')
639 udev_device_add_devlink(udev_device, slink);
640 } else if (strncmp(key, "DRIVER=", 7) == 0) {
641 udev_device_set_driver(udev_device, &key[7]);
642 } else if (strncmp(key, "ACTION=", 7) == 0) {
643 udev_device_set_action(udev_device, &key[7]);
645 } else if (strncmp(key, "MAJOR=", 6) == 0) {
646 maj = strtoull(&key[6], NULL, 10);
647 } else if (strncmp(key, "MINOR=", 6) == 0) {
648 min = strtoull(&key[6], NULL, 10);
649 } else if (strncmp(key, "DEVPATH_OLD=", 12) == 0) {
650 udev_device_set_devpath_old(udev_device, &key[12]);
651 } else if (strncmp(key, "SEQNUM=", 7) == 0) {
652 udev_device_set_seqnum(udev_device, strtoull(&key[7], NULL, 10));
653 } else if (strncmp(key, "TIMEOUT=", 8) == 0) {
654 udev_device_set_timeout(udev_device, strtoull(&key[8], NULL, 10));
656 udev_device_add_property_from_string(udev_device, key);
659 if (!devpath_set || !subsystem_set || !action_set) {
660 info(udev_monitor->udev, "missing values, skip\n");
661 udev_device_unref(udev_device);
665 /* skip device, if it does not pass the current filter */
666 if (!passes_filter(udev_monitor, udev_device)) {
667 struct pollfd pfd[1];
670 udev_device_unref(udev_device);
672 /* if something is queued, get next device */
673 pfd[0].fd = udev_monitor->sock;
674 pfd[0].events = POLLIN;
675 rc = poll(pfd, 1, 0);
682 udev_device_set_devnum(udev_device, makedev(maj, min));
683 udev_device_set_info_loaded(udev_device);
687 int udev_monitor_send_device(struct udev_monitor *udev_monitor,
688 struct udev_monitor *destination, struct udev_device *udev_device)
696 blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
700 if (udev_monitor->sun.sun_family != 0) {
705 /* header <action>@<devpath> */
706 action = udev_device_get_action(udev_device);
710 if (util_strpcpyl(&s, sizeof(header), action, "@", udev_device_get_devpath(udev_device), NULL) == 0)
712 iov[0].iov_base = header;
713 iov[0].iov_len = (s - header)+1;
715 /* add properties list */
716 iov[1].iov_base = (char *)buf;
717 iov[1].iov_len = blen;
719 memset(&smsg, 0x00, sizeof(struct msghdr));
722 smsg.msg_name = &udev_monitor->sun;
723 smsg.msg_namelen = udev_monitor->addrlen;
724 } else if (udev_monitor->snl.nl_family != 0) {
726 struct udev_monitor_netlink_header nlh;
729 /* add versioned header */
730 memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header));
731 util_strscpy(nlh.version, sizeof(nlh.version), "udev-" VERSION);
732 nlh.magic = htonl(UDEV_MONITOR_MAGIC);
733 val = udev_device_get_subsystem(udev_device);
734 nlh.filter_subsystem = htonl(util_string_hash32(val));
735 val = udev_device_get_devtype(udev_device);
737 nlh.filter_devtype = htonl(util_string_hash32(val));
738 iov[0].iov_base = &nlh;
739 iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
741 /* add properties list */
742 nlh.properties_off = iov[0].iov_len;
743 nlh.properties_len = blen;
744 iov[1].iov_base = (char *)buf;
745 iov[1].iov_len = blen;
747 memset(&smsg, 0x00, sizeof(struct msghdr));
751 * Use custom address for target, or the default one.
753 * If we send to a muticast group, we will get
754 * ECONNREFUSED, which is expected.
756 if (destination != NULL)
757 smsg.msg_name = &destination->snl;
759 smsg.msg_name = &udev_monitor->snl_destination;
760 smsg.msg_namelen = sizeof(struct sockaddr_nl);
765 count = sendmsg(udev_monitor->sock, &smsg, 0);
766 info(udev_monitor->udev, "passed %zi bytes to monitor %p\n", count, udev_monitor);
771 * udev_monitor_filter_add_match_subsystem_devtype:
772 * @udev_monitor: the monitor
773 * @subsystem: the subsystem value to match the incoming devices against
774 * @devtype: the devtype value to matvh the incoming devices against
776 * The filter must be installed before the monitor is switched to listening mode.
778 * Returns: 0 on success, otherwise a negative error value.
780 int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
782 if (udev_monitor == NULL)
784 if (subsystem == NULL)
786 if (udev_list_entry_add(udev_monitor->udev,
787 &udev_monitor->filter_subsystem_list, subsystem, devtype, 0, 0) == NULL)
793 * udev_monitor_filter_remove:
794 * @udev_monitor: monitor
796 * Remove all filters from monitor.
798 * Returns: 0 on success, otherwise a negative error value.
800 int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
802 static struct sock_fprog filter = { 0, NULL };
804 udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_subsystem_list);
805 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));