2 * libudev - interface to udev device information
4 * Copyright (C) 2008 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"
34 struct sockaddr_nl snl;
35 struct sockaddr_nl snl_peer;
36 struct sockaddr_un sun;
38 struct udev_list_node filter_subsystem_list;
41 enum udev_monitor_netlink_group {
42 UDEV_MONITOR_KERNEL = 1,
43 UDEV_MONITOR_UDEV = 2,
46 #define UDEV_MONITOR_MAGIC 0xcafe1dea
47 struct udev_monitor_netlink_header {
48 /* udev version text */
51 * magic to protect against daemon <-> library message format mismatch
52 * used in the kernel from socket filter rules; needs to be stored in network order
55 /* properties buffer */
56 unsigned short properties_off;
57 unsigned short properties_len;
59 * crc32 of some common device properties to filter with socket filters in the client
60 * used in the kernel from socket filter rules; needs to be stored in network order
62 unsigned int filter_subsystem;
65 static struct udev_monitor *udev_monitor_new(struct udev *udev)
67 struct udev_monitor *udev_monitor;
69 udev_monitor = calloc(1, sizeof(struct udev_monitor));
70 if (udev_monitor == NULL)
72 udev_monitor->refcount = 1;
73 udev_monitor->udev = udev;
74 udev_list_init(&udev_monitor->filter_subsystem_list);
79 * udev_monitor_new_from_socket:
80 * @udev: udev library context
81 * @socket_path: unix socket path
83 * Create new udev monitor and connect to a specified socket. The
84 * path to a socket either points to an existing socket file, or if
85 * the socket path starts with a '@' character, an abstract namespace
86 * socket will be used.
88 * A socket file will not be created. If it does not already exist,
89 * it will fall-back and connect to an abstract namespace socket with
90 * the given path. The permissions adjustment of a socket file, as
91 * well as the later cleanup, needs to be done by the caller.
93 * The initial refcount is 1, and needs to be decremented to
94 * release the resources of the udev monitor.
96 * Returns: a new udev monitor, or #NULL, in case of an error
98 struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
100 struct udev_monitor *udev_monitor;
105 if (socket_path == NULL)
107 udev_monitor = udev_monitor_new(udev);
108 if (udev_monitor == NULL)
111 udev_monitor->sun.sun_family = AF_LOCAL;
112 if (socket_path[0] == '@') {
113 /* translate leading '@' to abstract namespace */
114 util_strlcpy(udev_monitor->sun.sun_path, socket_path, sizeof(udev_monitor->sun.sun_path));
115 udev_monitor->sun.sun_path[0] = '\0';
116 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
117 } else if (stat(socket_path, &statbuf) == 0 && S_ISSOCK(statbuf.st_mode)) {
118 /* existing socket file */
119 util_strlcpy(udev_monitor->sun.sun_path, socket_path, sizeof(udev_monitor->sun.sun_path));
120 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
122 /* no socket file, assume abstract namespace socket */
123 util_strlcpy(&udev_monitor->sun.sun_path[1], socket_path, sizeof(udev_monitor->sun.sun_path)-1);
124 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path)+1;
126 udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
127 if (udev_monitor->sock == -1) {
128 err(udev, "error getting socket: %m\n");
132 util_set_fd_cloexec(udev_monitor->sock);
134 dbg(udev, "monitor %p created with '%s'\n", udev_monitor, socket_path);
139 * udev_monitor_new_from_netlink:
140 * @udev: udev library context
141 * @name: name of event source
143 * Create new udev monitor and connect to a specified event
144 * source. Valid sources identifiers are "udev" and "kernel".
146 * Applications should usually not connect directly to the
147 * "kernel" events, because the devices might not be useable
148 * at that time, before udev has configured them, and created
151 * Accessing devices at the same time as udev, might result
152 * in unpredictable behavior.
154 * The "udev" events are sent out after udev has finished its
155 * event processing, all rules have been processed, and needed
156 * device nodes are created.
158 * The initial refcount is 1, and needs to be decremented to
159 * release the resources of the udev monitor.
161 * Returns: a new udev monitor, or #NULL, in case of an error
163 struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
165 struct udev_monitor *udev_monitor;
173 if (strcmp(name, "kernel") == 0)
174 group = UDEV_MONITOR_KERNEL;
175 else if (strcmp(name, "udev") == 0)
176 group = UDEV_MONITOR_UDEV;
180 udev_monitor = udev_monitor_new(udev);
181 if (udev_monitor == NULL)
184 udev_monitor->sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
185 if (udev_monitor->sock == -1) {
186 err(udev, "error getting socket: %m\n");
190 util_set_fd_cloexec(udev_monitor->sock);
192 udev_monitor->snl.nl_family = AF_NETLINK;
193 udev_monitor->snl.nl_groups = group;
194 udev_monitor->snl_peer.nl_family = AF_NETLINK;
195 udev_monitor->snl_peer.nl_groups = UDEV_MONITOR_UDEV;
197 dbg(udev, "monitor %p created with NETLINK_KOBJECT_UEVENT (%u)\n", udev_monitor, group);
201 static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
202 unsigned short code, unsigned int data)
204 struct sock_filter *ins = &inss[*i];
211 static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
212 unsigned short code, unsigned int data,
213 unsigned short jt, unsigned short jf)
215 struct sock_filter *ins = &inss[*i];
224 static int filter_apply(struct udev_monitor *udev_monitor)
226 static struct sock_filter ins[256];
227 static struct sock_fprog filter;
229 struct udev_list_entry *list_entry;
232 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
235 memset(ins, 0x00, sizeof(ins));
238 /* load magic in accu */
239 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
240 /* jump if magic matches */
241 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
242 /* wrong magic, drop packet */
243 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
245 /* load filter_subsystem value in accu */
246 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem));
247 /* add all subsystem match values */
248 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
249 const char *subsys = udev_list_entry_get_name(list_entry);
252 crc = util_crc32((unsigned char *)subsys, strlen(subsys));
253 /* jump if value does not match */
254 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, crc, 0, 1);
255 /* matched, pass packet */
256 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
258 if (i+1 >= ARRAY_SIZE(ins))
261 /* nothing matched, drop packet */
262 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
267 err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
271 int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
276 if (udev_monitor->sun.sun_family != 0) {
277 err = bind(udev_monitor->sock,
278 (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
279 } else if (udev_monitor->snl.nl_family != 0) {
280 filter_apply(udev_monitor);
281 err = bind(udev_monitor->sock,
282 (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
288 err(udev_monitor->udev, "bind failed: %m\n");
292 /* enable receiving of sender credentials */
293 setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
297 int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
299 if (udev_monitor == NULL)
301 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
306 * @udev_monitor: udev monitor
308 * Take a reference of a udev monitor.
310 * Returns: the passed udev monitor
312 struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
314 if (udev_monitor == NULL)
316 udev_monitor->refcount++;
321 * udev_monitor_unref:
322 * @udev_monitor: udev monitor
324 * Drop a reference of a udev monitor. If the refcount reaches zero,
325 * the bound socket will be closed, and the resources of the monitor
329 void udev_monitor_unref(struct udev_monitor *udev_monitor)
331 if (udev_monitor == NULL)
333 udev_monitor->refcount--;
334 if (udev_monitor->refcount > 0)
336 if (udev_monitor->sock >= 0)
337 close(udev_monitor->sock);
338 udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_subsystem_list);
339 dbg(udev_monitor->udev, "monitor %p released\n", udev_monitor);
344 * udev_monitor_get_udev:
345 * @udev_monitor: udev monitor
347 * Retrieve the udev library context the monitor was created with.
349 * Returns: the udev library context
351 struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
353 if (udev_monitor == NULL)
355 return udev_monitor->udev;
359 * udev_monitor_get_fd:
360 * @udev_monitor: udev monitor
362 * Retrieve the socket file descriptor associated with the monitor.
364 * Returns: the socket file descriptor
366 int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
368 if (udev_monitor == NULL)
370 return udev_monitor->sock;
373 static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
375 struct udev_list_entry *list_entry;
378 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
381 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
382 const char *subsys = udev_device_get_subsystem(udev_device);
384 if (strcmp(udev_list_entry_get_name(list_entry), subsys) == 0) {
393 * udev_monitor_receive_device:
394 * @udev_monitor: udev monitor
396 * Receive data from the udev monitor socket, allocate a new udev
397 * device, fill in the received data, and return the device.
399 * Only socket connections with uid=0 are accepted. The caller
400 * needs to make sure that there is data to read from the socket.
401 * The call will block until the socket becomes readable.
403 * The initial refcount is 1, and needs to be decremented to
404 * release the resources of the udev device.
406 * Returns: a new udev device, or #NULL, in case of an error
408 struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
410 struct udev_device *udev_device;
413 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
414 struct cmsghdr *cmsg;
415 struct sockaddr_nl snl;
419 struct udev_monitor_netlink_header *nlh;
421 int subsystem_set = 0;
427 if (udev_monitor == NULL)
429 memset(buf, 0x00, sizeof(buf));
431 iov.iov_len = sizeof(buf);
432 memset (&smsg, 0x00, sizeof(struct msghdr));
435 smsg.msg_control = cred_msg;
436 smsg.msg_controllen = sizeof(cred_msg);
438 if (udev_monitor->snl.nl_family != 0) {
439 smsg.msg_name = &snl;
440 smsg.msg_namelen = sizeof(snl);
443 if (recvmsg(udev_monitor->sock, &smsg, 0) < 0) {
445 info(udev_monitor->udev, "unable to receive message\n");
449 if (udev_monitor->snl.nl_family != 0) {
450 if (snl.nl_groups == 0) {
451 info(udev_monitor->udev, "unicast netlink message ignored\n");
454 if ((snl.nl_groups == UDEV_MONITOR_KERNEL) && (snl.nl_pid > 0)) {
455 info(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n", snl.nl_pid);
460 cmsg = CMSG_FIRSTHDR(&smsg);
461 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
462 info(udev_monitor->udev, "no sender credentials received, message ignored\n");
466 cred = (struct ucred *)CMSG_DATA(cmsg);
467 if (cred->uid != 0) {
468 info(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
472 nlh = (struct udev_monitor_netlink_header *) buf;
473 if (nlh->magic == ntohl(UDEV_MONITOR_MAGIC)) {
474 /* udev message with version magic */
475 if (nlh->properties_off < sizeof(struct udev_monitor_netlink_header))
477 if (nlh->properties_off+32U > sizeof(buf))
479 bufpos = nlh->properties_off;
481 /* kernel message with header */
482 bufpos = strlen(buf) + 1;
483 if (bufpos < sizeof("a@/d") || bufpos >= sizeof(buf)) {
484 info(udev_monitor->udev, "invalid message length\n");
488 /* check message header */
489 if (strstr(buf, "@/") == NULL) {
490 info(udev_monitor->udev, "unrecognized message header\n");
495 udev_device = device_new(udev_monitor->udev);
496 if (udev_device == NULL) {
500 while (bufpos < sizeof(buf)) {
505 keylen = strlen(key);
508 bufpos += keylen + 1;
510 if (strncmp(key, "DEVPATH=", 8) == 0) {
511 char path[UTIL_PATH_SIZE];
513 util_strlcpy(path, udev_get_sys_path(udev_monitor->udev), sizeof(path));
514 util_strlcat(path, &key[8], sizeof(path));
515 udev_device_set_syspath(udev_device, path);
517 } else if (strncmp(key, "SUBSYSTEM=", 10) == 0) {
518 udev_device_set_subsystem(udev_device, &key[10]);
520 } else if (strncmp(key, "DEVTYPE=", 8) == 0) {
521 udev_device_set_devtype(udev_device, &key[8]);
522 } else if (strncmp(key, "DEVNAME=", 8) == 0) {
523 udev_device_set_devnode(udev_device, &key[8]);
524 } else if (strncmp(key, "DEVLINKS=", 9) == 0) {
525 char devlinks[UTIL_PATH_SIZE];
529 util_strlcpy(devlinks, &key[9], sizeof(devlinks));
531 next = strchr(slink, ' ');
532 while (next != NULL) {
534 udev_device_add_devlink(udev_device, slink);
536 next = strchr(slink, ' ');
538 if (slink[0] != '\0')
539 udev_device_add_devlink(udev_device, slink);
540 } else if (strncmp(key, "DRIVER=", 7) == 0) {
541 udev_device_set_driver(udev_device, &key[7]);
542 } else if (strncmp(key, "ACTION=", 7) == 0) {
543 udev_device_set_action(udev_device, &key[7]);
545 } else if (strncmp(key, "MAJOR=", 6) == 0) {
546 maj = strtoull(&key[6], NULL, 10);
547 } else if (strncmp(key, "MINOR=", 6) == 0) {
548 min = strtoull(&key[6], NULL, 10);
549 } else if (strncmp(key, "DEVPATH_OLD=", 12) == 0) {
550 udev_device_set_devpath_old(udev_device, &key[12]);
551 } else if (strncmp(key, "PHYSDEVPATH=", 12) == 0) {
552 udev_device_set_physdevpath(udev_device, &key[12]);
553 } else if (strncmp(key, "SEQNUM=", 7) == 0) {
554 udev_device_set_seqnum(udev_device, strtoull(&key[7], NULL, 10));
555 } else if (strncmp(key, "TIMEOUT=", 8) == 0) {
556 udev_device_set_timeout(udev_device, strtoull(&key[8], NULL, 10));
557 } else if (strncmp(key, "PHYSDEV", 7) == 0) {
558 /* skip deprecated values */
561 udev_device_add_property_from_string(udev_device, key);
564 if (!devpath_set || !subsystem_set || !action_set) {
565 info(udev_monitor->udev, "missing values, skip\n");
566 udev_device_unref(udev_device);
570 /* skip device, if it does not pass the current filter */
571 if (!passes_filter(udev_monitor, udev_device)) {
572 struct pollfd pfd[1];
575 udev_device_unref(udev_device);
577 /* if something is queued, get next device */
578 pfd[0].fd = udev_monitor->sock;
579 pfd[0].events = POLLIN;
580 rc = poll(pfd, 1, 0);
587 udev_device_set_devnum(udev_device, makedev(maj, min));
588 udev_device_set_info_loaded(udev_device);
592 int udev_monitor_send_device(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
600 blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
604 if (udev_monitor->sun.sun_family != 0) {
609 /* header <action>@<devpath> */
610 action = udev_device_get_action(udev_device);
613 util_strlcpy(header, action, sizeof(header));
614 util_strlcat(header, "@", sizeof(header));
615 hlen = util_strlcat(header, udev_device_get_devpath(udev_device), sizeof(header))+1;
616 if (hlen >= sizeof(header))
618 iov[0].iov_base = header;
619 iov[0].iov_len = hlen;
621 /* add properties list */
622 iov[1].iov_base = (char *)buf;
623 iov[1].iov_len = blen;
625 memset(&smsg, 0x00, sizeof(struct msghdr));
628 smsg.msg_name = &udev_monitor->sun;
629 smsg.msg_namelen = udev_monitor->addrlen;
630 } else if (udev_monitor->snl.nl_family != 0) {
633 struct udev_monitor_netlink_header nlh;
636 /* add versioned header */
637 memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header));
638 util_strlcpy(nlh.version, "udev-" VERSION, sizeof(nlh.version));
639 nlh.magic = htonl(UDEV_MONITOR_MAGIC);
640 val = udev_device_get_subsystem(udev_device);
642 nlh.filter_subsystem = htonl(util_crc32((unsigned char *)val, vlen));
643 iov[0].iov_base = &nlh;
644 iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
646 /* add properties list */
647 nlh.properties_off = iov[0].iov_len;
648 nlh.properties_len = blen;
649 iov[1].iov_base = (char *)buf;
650 iov[1].iov_len = blen;
652 memset(&smsg, 0x00, sizeof(struct msghdr));
655 /* no destination besides the muticast group, we will always get ECONNREFUSED */
656 smsg.msg_name = &udev_monitor->snl_peer;
657 smsg.msg_namelen = sizeof(struct sockaddr_nl);
662 count = sendmsg(udev_monitor->sock, &smsg, 0);
663 info(udev_monitor->udev, "passed %zi bytes to monitor %p\n", count, udev_monitor);
667 int udev_monitor_filter_add_match_subsystem(struct udev_monitor *udev_monitor, const char *subsystem)
669 if (udev_monitor == NULL)
671 if (subsystem == NULL)
673 if (udev_list_entry_add(udev_monitor->udev,
674 &udev_monitor->filter_subsystem_list, subsystem, NULL, 1, 0) == NULL)