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.
40 * Opaque object handling one event source.
46 struct sockaddr_nl snl;
47 struct sockaddr_nl snl_trusted_sender;
48 struct sockaddr_nl snl_destination;
49 struct sockaddr_un sun;
51 struct udev_list_node filter_subsystem_list;
54 enum udev_monitor_netlink_group {
60 #define UDEV_MONITOR_MAGIC 0xcafe1dea
61 struct udev_monitor_netlink_header {
62 /* udev version text */
65 * magic to protect against daemon <-> library message format mismatch
66 * used in the kernel from socket filter rules; needs to be stored in network order
69 /* properties buffer */
70 unsigned short properties_off;
71 unsigned short properties_len;
73 * hashes of some common device properties strings to filter with socket filters in
74 * the client used in the kernel from socket filter rules; needs to be stored in
77 unsigned int filter_subsystem;
78 unsigned int filter_devtype;
81 static struct udev_monitor *udev_monitor_new(struct udev *udev)
83 struct udev_monitor *udev_monitor;
85 udev_monitor = calloc(1, sizeof(struct udev_monitor));
86 if (udev_monitor == NULL)
88 udev_monitor->refcount = 1;
89 udev_monitor->udev = udev;
90 udev_list_init(&udev_monitor->filter_subsystem_list);
95 * udev_monitor_new_from_socket:
96 * @udev: udev library context
97 * @socket_path: unix socket path
99 * Create new udev monitor and connect to a specified socket. The
100 * path to a socket either points to an existing socket file, or if
101 * the socket path starts with a '@' character, an abstract namespace
102 * socket will be used.
104 * A socket file will not be created. If it does not already exist,
105 * it will fall-back and connect to an abstract namespace socket with
106 * the given path. The permissions adjustment of a socket file, as
107 * well as the later cleanup, needs to be done by the caller.
109 * The initial refcount is 1, and needs to be decremented to
110 * release the resources of the udev monitor.
112 * Returns: a new udev monitor, or #NULL, in case of an error
114 struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
116 struct udev_monitor *udev_monitor;
121 if (socket_path == NULL)
123 udev_monitor = udev_monitor_new(udev);
124 if (udev_monitor == NULL)
127 udev_monitor->sun.sun_family = AF_LOCAL;
128 if (socket_path[0] == '@') {
129 /* translate leading '@' to abstract namespace */
130 util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
131 udev_monitor->sun.sun_path[0] = '\0';
132 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
133 } else if (stat(socket_path, &statbuf) == 0 && S_ISSOCK(statbuf.st_mode)) {
134 /* existing socket file */
135 util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
136 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
138 /* no socket file, assume abstract namespace socket */
139 util_strscpy(&udev_monitor->sun.sun_path[1], sizeof(udev_monitor->sun.sun_path)-1, socket_path);
140 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path)+1;
142 udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
143 if (udev_monitor->sock == -1) {
144 err(udev, "error getting socket: %m\n");
148 util_set_fd_cloexec(udev_monitor->sock);
150 dbg(udev, "monitor %p created with '%s'\n", udev_monitor, socket_path);
155 * udev_monitor_new_from_netlink:
156 * @udev: udev library context
157 * @name: name of event source
159 * Create new udev monitor and connect to a specified event
160 * source. Valid sources identifiers are "udev" and "kernel".
162 * Applications should usually not connect directly to the
163 * "kernel" events, because the devices might not be useable
164 * at that time, before udev has configured them, and created
167 * Accessing devices at the same time as udev, might result
168 * in unpredictable behavior.
170 * The "udev" events are sent out after udev has finished its
171 * event processing, all rules have been processed, and needed
172 * device nodes are created.
174 * The initial refcount is 1, and needs to be decremented to
175 * release the resources of the udev monitor.
177 * Returns: a new udev monitor, or #NULL, in case of an error
179 struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
181 struct udev_monitor *udev_monitor;
188 group = UDEV_MONITOR_NONE;
189 else if (strcmp(name, "udev") == 0)
190 group = UDEV_MONITOR_UDEV;
191 else if (strcmp(name, "kernel") == 0)
192 group = UDEV_MONITOR_KERNEL;
196 udev_monitor = udev_monitor_new(udev);
197 if (udev_monitor == NULL)
200 udev_monitor->sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
201 if (udev_monitor->sock == -1) {
202 err(udev, "error getting socket: %m\n");
206 util_set_fd_cloexec(udev_monitor->sock);
208 udev_monitor->snl.nl_family = AF_NETLINK;
209 udev_monitor->snl.nl_groups = group;
211 /* default destination for sending */
212 udev_monitor->snl_destination.nl_family = AF_NETLINK;
213 udev_monitor->snl_destination.nl_groups = UDEV_MONITOR_UDEV;
215 dbg(udev, "monitor %p created with NETLINK_KOBJECT_UEVENT (%u)\n", udev_monitor, group);
219 static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
220 unsigned short code, unsigned int data)
222 struct sock_filter *ins = &inss[*i];
229 static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
230 unsigned short code, unsigned int data,
231 unsigned short jt, unsigned short jf)
233 struct sock_filter *ins = &inss[*i];
243 * udev_monitor_filter_update:
244 * @udev_monitor: monitor
246 * Update the installed filter. This might only be needed, if the filter was removed or changed.
248 * Returns: 0 on success, otherwise a negative error value.
250 int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
252 static struct sock_filter ins[256];
253 static struct sock_fprog filter;
255 struct udev_list_entry *list_entry;
258 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
261 memset(ins, 0x00, sizeof(ins));
264 /* load magic in A */
265 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
266 /* jump if magic matches */
267 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
268 /* wrong magic, pass packet */
269 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
271 /* add all subsystem match values */
272 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
275 /* load filter_subsystem value in A */
276 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem));
277 hash = util_string_hash32(udev_list_entry_get_name(list_entry));
278 if (udev_list_entry_get_value(list_entry) == NULL) {
279 /* jump if subsystem does not match */
280 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
282 /* jump if subsystem does not match */
283 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
285 /* load filter_devtype value in A */
286 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype));
287 /* jump if value does not match */
288 hash = util_string_hash32(udev_list_entry_get_value(list_entry));
289 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
292 /* matched, pass packet */
293 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
295 if (i+1 >= ARRAY_SIZE(ins))
298 /* nothing matched, drop packet */
299 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
304 err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
308 int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
310 udev_monitor->snl_trusted_sender.nl_pid = sender->snl.nl_pid;
314 * udev_monitor_enable_receiving:
315 * @udev_monitor: the monitor which should receive events
317 * Binds the @udev_monitor socket to the event source.
319 * Returns: 0 on success, otherwise a negative error value.
321 int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
326 if (udev_monitor->sun.sun_family != 0) {
327 err = bind(udev_monitor->sock,
328 (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
329 } else if (udev_monitor->snl.nl_family != 0) {
330 udev_monitor_filter_update(udev_monitor);
331 err = bind(udev_monitor->sock,
332 (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
334 struct sockaddr_nl snl;
338 * get the address the kernel has assigned us
339 * it is usually, but not necessarily the pid
341 addrlen = sizeof(struct sockaddr_nl);
342 err = getsockname(udev_monitor->sock, (struct sockaddr *)&snl, &addrlen);
344 udev_monitor->snl.nl_pid = snl.nl_pid;
351 err(udev_monitor->udev, "bind failed: %m\n");
355 /* enable receiving of sender credentials */
356 setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
360 int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
362 if (udev_monitor == NULL)
364 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
367 int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
371 err = close(udev_monitor->sock);
372 udev_monitor->sock = -1;
378 * @udev_monitor: udev monitor
380 * Take a reference of a udev monitor.
382 * Returns: the passed udev monitor
384 struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
386 if (udev_monitor == NULL)
388 udev_monitor->refcount++;
393 * udev_monitor_unref:
394 * @udev_monitor: udev monitor
396 * Drop a reference of a udev monitor. If the refcount reaches zero,
397 * the bound socket will be closed, and the resources of the monitor
401 void udev_monitor_unref(struct udev_monitor *udev_monitor)
403 if (udev_monitor == NULL)
405 udev_monitor->refcount--;
406 if (udev_monitor->refcount > 0)
408 if (udev_monitor->sock >= 0)
409 close(udev_monitor->sock);
410 udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_subsystem_list);
411 dbg(udev_monitor->udev, "monitor %p released\n", udev_monitor);
416 * udev_monitor_get_udev:
417 * @udev_monitor: udev monitor
419 * Retrieve the udev library context the monitor was created with.
421 * Returns: the udev library context
423 struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
425 if (udev_monitor == NULL)
427 return udev_monitor->udev;
431 * udev_monitor_get_fd:
432 * @udev_monitor: udev monitor
434 * Retrieve the socket file descriptor associated with the monitor.
436 * Returns: the socket file descriptor
438 int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
440 if (udev_monitor == NULL)
442 return udev_monitor->sock;
445 static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
447 struct udev_list_entry *list_entry;
449 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
452 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
453 const char *subsys = udev_list_entry_get_name(list_entry);
454 const char *dsubsys = udev_device_get_subsystem(udev_device);
456 const char *ddevtype;
458 if (strcmp(dsubsys, subsys) != 0)
461 devtype = udev_list_entry_get_value(list_entry);
464 ddevtype = udev_device_get_devtype(udev_device);
465 if (ddevtype == NULL)
467 if (strcmp(ddevtype, devtype) == 0)
474 * udev_monitor_receive_device:
475 * @udev_monitor: udev monitor
477 * Receive data from the udev monitor socket, allocate a new udev
478 * device, fill in the received data, and return the device.
480 * Only socket connections with uid=0 are accepted. The caller
481 * needs to make sure that there is data to read from the socket.
482 * The call will block until the socket becomes readable.
484 * The initial refcount is 1, and needs to be decremented to
485 * release the resources of the udev device.
487 * Returns: a new udev device, or #NULL, in case of an error
489 struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
491 struct udev_device *udev_device;
494 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
495 struct cmsghdr *cmsg;
496 struct sockaddr_nl snl;
501 struct udev_monitor_netlink_header *nlh;
503 int subsystem_set = 0;
509 if (udev_monitor == NULL)
511 memset(buf, 0x00, sizeof(buf));
513 iov.iov_len = sizeof(buf);
514 memset (&smsg, 0x00, sizeof(struct msghdr));
517 smsg.msg_control = cred_msg;
518 smsg.msg_controllen = sizeof(cred_msg);
520 if (udev_monitor->snl.nl_family != 0) {
521 smsg.msg_name = &snl;
522 smsg.msg_namelen = sizeof(snl);
525 buflen = recvmsg(udev_monitor->sock, &smsg, 0);
528 info(udev_monitor->udev, "unable to receive message\n");
532 if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
533 info(udev_monitor->udev, "invalid message length\n");
537 if (udev_monitor->snl.nl_family != 0) {
538 if (snl.nl_groups == 0) {
539 /* unicast message, check if we trust the sender */
540 if (udev_monitor->snl_trusted_sender.nl_pid == 0 ||
541 snl.nl_pid != udev_monitor->snl_trusted_sender.nl_pid) {
542 info(udev_monitor->udev, "unicast netlink message ignored\n");
545 } else if (snl.nl_groups == UDEV_MONITOR_KERNEL) {
546 if (snl.nl_pid > 0) {
547 info(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n",
554 cmsg = CMSG_FIRSTHDR(&smsg);
555 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
556 info(udev_monitor->udev, "no sender credentials received, message ignored\n");
560 cred = (struct ucred *)CMSG_DATA(cmsg);
561 if (cred->uid != 0) {
562 info(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
566 if (strncmp(buf, "udev-", 5) == 0) {
567 /* udev message needs proper version magic */
568 nlh = (struct udev_monitor_netlink_header *) buf;
569 if (nlh->magic != htonl(UDEV_MONITOR_MAGIC))
571 if (nlh->properties_off < sizeof(struct udev_monitor_netlink_header))
573 if (nlh->properties_off+32 > buflen)
575 bufpos = nlh->properties_off;
577 /* kernel message with header */
578 bufpos = strlen(buf) + 1;
579 if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
580 info(udev_monitor->udev, "invalid message length\n");
584 /* check message header */
585 if (strstr(buf, "@/") == NULL) {
586 info(udev_monitor->udev, "unrecognized message header\n");
591 udev_device = udev_device_new(udev_monitor->udev);
592 if (udev_device == NULL)
595 while (bufpos < buflen) {
600 keylen = strlen(key);
603 bufpos += keylen + 1;
605 if (strncmp(key, "DEVPATH=", 8) == 0) {
606 char path[UTIL_PATH_SIZE];
608 util_strscpyl(path, sizeof(path), udev_get_sys_path(udev_monitor->udev), &key[8], NULL);
609 udev_device_set_syspath(udev_device, path);
611 } else if (strncmp(key, "SUBSYSTEM=", 10) == 0) {
612 udev_device_set_subsystem(udev_device, &key[10]);
614 } else if (strncmp(key, "DEVTYPE=", 8) == 0) {
615 udev_device_set_devtype(udev_device, &key[8]);
616 } else if (strncmp(key, "DEVNAME=", 8) == 0) {
618 udev_device_set_devnode(udev_device, &key[8]);
620 udev_device_set_knodename(udev_device, &key[8]);
621 } else if (strncmp(key, "DEVLINKS=", 9) == 0) {
622 char devlinks[UTIL_PATH_SIZE];
626 util_strscpy(devlinks, sizeof(devlinks), &key[9]);
628 next = strchr(slink, ' ');
629 while (next != NULL) {
631 udev_device_add_devlink(udev_device, slink, 0);
633 next = strchr(slink, ' ');
635 if (slink[0] != '\0')
636 udev_device_add_devlink(udev_device, slink, 0);
637 } else if (strncmp(key, "DRIVER=", 7) == 0) {
638 udev_device_set_driver(udev_device, &key[7]);
639 } else if (strncmp(key, "ACTION=", 7) == 0) {
640 udev_device_set_action(udev_device, &key[7]);
642 } else if (strncmp(key, "MAJOR=", 6) == 0) {
643 maj = strtoull(&key[6], NULL, 10);
644 } else if (strncmp(key, "MINOR=", 6) == 0) {
645 min = strtoull(&key[6], NULL, 10);
646 } else if (strncmp(key, "DEVPATH_OLD=", 12) == 0) {
647 udev_device_set_devpath_old(udev_device, &key[12]);
648 } else if (strncmp(key, "SEQNUM=", 7) == 0) {
649 udev_device_set_seqnum(udev_device, strtoull(&key[7], NULL, 10));
650 } else if (strncmp(key, "TIMEOUT=", 8) == 0) {
651 udev_device_set_timeout(udev_device, strtoull(&key[8], NULL, 10));
653 udev_device_add_property_from_string(udev_device, key);
656 if (!devpath_set || !subsystem_set || !action_set) {
657 info(udev_monitor->udev, "missing values, skip\n");
658 udev_device_unref(udev_device);
662 /* skip device, if it does not pass the current filter */
663 if (!passes_filter(udev_monitor, udev_device)) {
664 struct pollfd pfd[1];
667 udev_device_unref(udev_device);
669 /* if something is queued, get next device */
670 pfd[0].fd = udev_monitor->sock;
671 pfd[0].events = POLLIN;
672 rc = poll(pfd, 1, 0);
679 udev_device_set_devnum(udev_device, makedev(maj, min));
680 udev_device_set_info_loaded(udev_device);
684 int udev_monitor_send_device(struct udev_monitor *udev_monitor,
685 struct udev_monitor *destination, struct udev_device *udev_device)
693 blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
697 if (udev_monitor->sun.sun_family != 0) {
702 /* header <action>@<devpath> */
703 action = udev_device_get_action(udev_device);
707 if (util_strpcpyl(&s, sizeof(header), action, "@", udev_device_get_devpath(udev_device), NULL) == 0)
709 iov[0].iov_base = header;
710 iov[0].iov_len = (s - header)+1;
712 /* add properties list */
713 iov[1].iov_base = (char *)buf;
714 iov[1].iov_len = blen;
716 memset(&smsg, 0x00, sizeof(struct msghdr));
719 smsg.msg_name = &udev_monitor->sun;
720 smsg.msg_namelen = udev_monitor->addrlen;
721 } else if (udev_monitor->snl.nl_family != 0) {
723 struct udev_monitor_netlink_header nlh;
726 /* add versioned header */
727 memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header));
728 util_strscpy(nlh.version, sizeof(nlh.version), "udev-" VERSION);
729 nlh.magic = htonl(UDEV_MONITOR_MAGIC);
730 val = udev_device_get_subsystem(udev_device);
731 nlh.filter_subsystem = htonl(util_string_hash32(val));
732 val = udev_device_get_devtype(udev_device);
734 nlh.filter_devtype = htonl(util_string_hash32(val));
735 iov[0].iov_base = &nlh;
736 iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
738 /* add properties list */
739 nlh.properties_off = iov[0].iov_len;
740 nlh.properties_len = blen;
741 iov[1].iov_base = (char *)buf;
742 iov[1].iov_len = blen;
744 memset(&smsg, 0x00, sizeof(struct msghdr));
748 * Use custom address for target, or the default one.
750 * If we send to a multicast group, we will get
751 * ECONNREFUSED, which is expected.
753 if (destination != NULL)
754 smsg.msg_name = &destination->snl;
756 smsg.msg_name = &udev_monitor->snl_destination;
757 smsg.msg_namelen = sizeof(struct sockaddr_nl);
762 count = sendmsg(udev_monitor->sock, &smsg, 0);
763 info(udev_monitor->udev, "passed %zi bytes to monitor %p\n", count, udev_monitor);
768 * udev_monitor_filter_add_match_subsystem_devtype:
769 * @udev_monitor: the monitor
770 * @subsystem: the subsystem value to match the incoming devices against
771 * @devtype: the devtype value to match the incoming devices against
773 * The filter must be installed before the monitor is switched to listening mode.
775 * Returns: 0 on success, otherwise a negative error value.
777 int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
779 if (udev_monitor == NULL)
781 if (subsystem == NULL)
783 if (udev_list_entry_add(udev_monitor->udev,
784 &udev_monitor->filter_subsystem_list, subsystem, devtype, 0, 0) == NULL)
790 * udev_monitor_filter_remove:
791 * @udev_monitor: monitor
793 * Remove all filters from monitor.
795 * Returns: 0 on success, otherwise a negative error value.
797 int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
799 static struct sock_fprog filter = { 0, NULL };
801 udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_subsystem_list);
802 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));