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663996b3 MS |
1 | /*** |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright 2008-2012 Kay Sievers <kay@vrfy.org> | |
5 | ||
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. | |
10 | ||
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. | |
15 | ||
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/>. | |
18 | ***/ | |
19 | ||
20 | #include <stdio.h> | |
21 | #include <stdlib.h> | |
22 | #include <stddef.h> | |
23 | #include <unistd.h> | |
24 | #include <errno.h> | |
25 | #include <string.h> | |
26 | #include <dirent.h> | |
e735f4d4 | 27 | #include <poll.h> |
663996b3 MS |
28 | #include <sys/stat.h> |
29 | #include <sys/socket.h> | |
30 | #include <sys/un.h> | |
31 | #include <arpa/inet.h> | |
32 | #include <linux/netlink.h> | |
33 | #include <linux/filter.h> | |
34 | ||
35 | #include "libudev.h" | |
36 | #include "libudev-private.h" | |
37 | #include "socket-util.h" | |
60f067b4 | 38 | #include "missing.h" |
663996b3 MS |
39 | |
40 | /** | |
41 | * SECTION:libudev-monitor | |
42 | * @short_description: device event source | |
43 | * | |
44 | * Connects to a device event source. | |
45 | */ | |
46 | ||
47 | /** | |
48 | * udev_monitor: | |
49 | * | |
50 | * Opaque object handling an event source. | |
51 | */ | |
52 | struct udev_monitor { | |
53 | struct udev *udev; | |
54 | int refcount; | |
55 | int sock; | |
56 | union sockaddr_union snl; | |
57 | union sockaddr_union snl_trusted_sender; | |
58 | union sockaddr_union snl_destination; | |
59 | socklen_t addrlen; | |
60 | struct udev_list filter_subsystem_list; | |
61 | struct udev_list filter_tag_list; | |
62 | bool bound; | |
63 | }; | |
64 | ||
65 | enum udev_monitor_netlink_group { | |
66 | UDEV_MONITOR_NONE, | |
67 | UDEV_MONITOR_KERNEL, | |
68 | UDEV_MONITOR_UDEV, | |
69 | }; | |
70 | ||
71 | #define UDEV_MONITOR_MAGIC 0xfeedcafe | |
72 | struct udev_monitor_netlink_header { | |
73 | /* "libudev" prefix to distinguish libudev and kernel messages */ | |
74 | char prefix[8]; | |
75 | /* | |
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 | |
78 | */ | |
79 | unsigned int magic; | |
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; | |
85 | /* | |
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 | |
88 | */ | |
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; | |
93 | }; | |
94 | ||
95 | static struct udev_monitor *udev_monitor_new(struct udev *udev) | |
96 | { | |
97 | struct udev_monitor *udev_monitor; | |
98 | ||
60f067b4 | 99 | udev_monitor = new0(struct udev_monitor, 1); |
663996b3 MS |
100 | if (udev_monitor == NULL) |
101 | return 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); | |
106 | return udev_monitor; | |
107 | } | |
108 | ||
60f067b4 JS |
109 | /* we consider udev running when /dev is on devtmpfs */ |
110 | static bool udev_has_devtmpfs(struct udev *udev) { | |
111 | ||
e735f4d4 | 112 | union file_handle_union h = FILE_HANDLE_INIT; |
60f067b4 JS |
113 | _cleanup_fclose_ FILE *f = NULL; |
114 | char line[LINE_MAX], *e; | |
115 | int mount_id; | |
116 | int r; | |
117 | ||
118 | r = name_to_handle_at(AT_FDCWD, "/dev", &h.handle, &mount_id, 0); | |
119 | if (r < 0) { | |
120 | if (errno != EOPNOTSUPP) | |
f47781d8 | 121 | log_debug_errno(errno, "name_to_handle_at on /dev: %m"); |
60f067b4 JS |
122 | return false; |
123 | } | |
124 | ||
125 | f = fopen("/proc/self/mountinfo", "re"); | |
126 | if (!f) | |
127 | return false; | |
128 | ||
129 | FOREACH_LINE(line, f, return false) { | |
130 | int mid; | |
131 | ||
132 | if (sscanf(line, "%i", &mid) != 1) | |
133 | continue; | |
134 | ||
135 | if (mid != mount_id) | |
136 | continue; | |
137 | ||
138 | e = strstr(line, " - "); | |
139 | if (!e) | |
140 | continue; | |
141 | ||
142 | /* accept any name that starts with the currently expected type */ | |
143 | if (startswith(e + 3, "devtmpfs")) | |
144 | return true; | |
145 | } | |
146 | ||
147 | return false; | |
148 | } | |
149 | ||
663996b3 MS |
150 | struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd) |
151 | { | |
152 | struct udev_monitor *udev_monitor; | |
153 | unsigned int group; | |
154 | ||
155 | if (udev == NULL) | |
156 | return NULL; | |
157 | ||
158 | if (name == NULL) | |
159 | group = UDEV_MONITOR_NONE; | |
60f067b4 JS |
160 | else if (streq(name, "udev")) { |
161 | /* | |
162 | * We do not support subscribing to uevents if no instance of | |
163 | * udev is running. Uevents would otherwise broadcast the | |
164 | * processing data of the host into containers, which is not | |
165 | * desired. | |
166 | * | |
167 | * Containers will currently not get any udev uevents, until | |
168 | * a supporting infrastructure is available. | |
169 | * | |
170 | * We do not set a netlink multicast group here, so the socket | |
171 | * will not receive any messages. | |
172 | */ | |
173 | if (access("/run/udev/control", F_OK) < 0 && !udev_has_devtmpfs(udev)) { | |
f47781d8 | 174 | log_debug("the udev service seems not to be active, disable the monitor"); |
60f067b4 JS |
175 | group = UDEV_MONITOR_NONE; |
176 | } else | |
177 | group = UDEV_MONITOR_UDEV; | |
178 | } else if (streq(name, "kernel")) | |
663996b3 MS |
179 | group = UDEV_MONITOR_KERNEL; |
180 | else | |
181 | return NULL; | |
182 | ||
183 | udev_monitor = udev_monitor_new(udev); | |
184 | if (udev_monitor == NULL) | |
185 | return NULL; | |
186 | ||
187 | if (fd < 0) { | |
188 | udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT); | |
189 | if (udev_monitor->sock == -1) { | |
f47781d8 | 190 | log_debug_errno(errno, "error getting socket: %m"); |
663996b3 MS |
191 | free(udev_monitor); |
192 | return NULL; | |
193 | } | |
194 | } else { | |
195 | udev_monitor->bound = true; | |
196 | udev_monitor->sock = fd; | |
197 | } | |
198 | ||
199 | udev_monitor->snl.nl.nl_family = AF_NETLINK; | |
200 | udev_monitor->snl.nl.nl_groups = group; | |
201 | ||
202 | /* default destination for sending */ | |
203 | udev_monitor->snl_destination.nl.nl_family = AF_NETLINK; | |
204 | udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV; | |
205 | ||
206 | return udev_monitor; | |
207 | } | |
208 | ||
209 | /** | |
210 | * udev_monitor_new_from_netlink: | |
211 | * @udev: udev library context | |
212 | * @name: name of event source | |
213 | * | |
214 | * Create new udev monitor and connect to a specified event | |
215 | * source. Valid sources identifiers are "udev" and "kernel". | |
216 | * | |
217 | * Applications should usually not connect directly to the | |
218 | * "kernel" events, because the devices might not be useable | |
219 | * at that time, before udev has configured them, and created | |
220 | * device nodes. Accessing devices at the same time as udev, | |
221 | * might result in unpredictable behavior. The "udev" events | |
222 | * are sent out after udev has finished its event processing, | |
223 | * all rules have been processed, and needed device nodes are | |
224 | * created. | |
225 | * | |
226 | * The initial refcount is 1, and needs to be decremented to | |
227 | * release the resources of the udev monitor. | |
228 | * | |
229 | * Returns: a new udev monitor, or #NULL, in case of an error | |
230 | **/ | |
231 | _public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name) | |
232 | { | |
233 | return udev_monitor_new_from_netlink_fd(udev, name, -1); | |
234 | } | |
235 | ||
236 | static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i, | |
237 | unsigned short code, unsigned int data) | |
238 | { | |
239 | struct sock_filter *ins = &inss[*i]; | |
240 | ||
241 | ins->code = code; | |
242 | ins->k = data; | |
243 | (*i)++; | |
244 | } | |
245 | ||
246 | static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i, | |
247 | unsigned short code, unsigned int data, | |
248 | unsigned short jt, unsigned short jf) | |
249 | { | |
250 | struct sock_filter *ins = &inss[*i]; | |
251 | ||
252 | ins->code = code; | |
253 | ins->jt = jt; | |
254 | ins->jf = jf; | |
255 | ins->k = data; | |
256 | (*i)++; | |
257 | } | |
258 | ||
259 | /** | |
260 | * udev_monitor_filter_update: | |
261 | * @udev_monitor: monitor | |
262 | * | |
263 | * Update the installed socket filter. This is only needed, | |
264 | * if the filter was removed or changed. | |
265 | * | |
266 | * Returns: 0 on success, otherwise a negative error value. | |
267 | */ | |
268 | _public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor) | |
269 | { | |
270 | struct sock_filter ins[512]; | |
271 | struct sock_fprog filter; | |
272 | unsigned int i; | |
273 | struct udev_list_entry *list_entry; | |
274 | int err; | |
275 | ||
276 | if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL && | |
277 | udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL) | |
278 | return 0; | |
279 | ||
60f067b4 | 280 | memzero(ins, sizeof(ins)); |
663996b3 MS |
281 | i = 0; |
282 | ||
283 | /* load magic in A */ | |
284 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic)); | |
285 | /* jump if magic matches */ | |
286 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0); | |
287 | /* wrong magic, pass packet */ | |
288 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); | |
289 | ||
290 | if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) { | |
291 | int tag_matches; | |
292 | ||
293 | /* count tag matches, to calculate end of tag match block */ | |
294 | tag_matches = 0; | |
295 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) | |
296 | tag_matches++; | |
297 | ||
298 | /* add all tags matches */ | |
299 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) { | |
300 | uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry)); | |
301 | uint32_t tag_bloom_hi = tag_bloom_bits >> 32; | |
302 | uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff; | |
303 | ||
304 | /* load device bloom bits in A */ | |
305 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi)); | |
306 | /* clear bits (tag bits & bloom bits) */ | |
307 | bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi); | |
308 | /* jump to next tag if it does not match */ | |
309 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3); | |
310 | ||
311 | /* load device bloom bits in A */ | |
312 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo)); | |
313 | /* clear bits (tag bits & bloom bits) */ | |
314 | bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo); | |
315 | /* jump behind end of tag match block if tag matches */ | |
316 | tag_matches--; | |
317 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0); | |
318 | } | |
319 | ||
320 | /* nothing matched, drop packet */ | |
321 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0); | |
322 | } | |
323 | ||
324 | /* add all subsystem matches */ | |
325 | if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) { | |
326 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) { | |
327 | unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry)); | |
328 | ||
329 | /* load device subsystem value in A */ | |
330 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash)); | |
331 | if (udev_list_entry_get_value(list_entry) == NULL) { | |
332 | /* jump if subsystem does not match */ | |
333 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1); | |
334 | } else { | |
335 | /* jump if subsystem does not match */ | |
336 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3); | |
337 | ||
338 | /* load device devtype value in A */ | |
339 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash)); | |
340 | /* jump if value does not match */ | |
341 | hash = util_string_hash32(udev_list_entry_get_value(list_entry)); | |
342 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1); | |
343 | } | |
344 | ||
345 | /* matched, pass packet */ | |
346 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); | |
347 | ||
348 | if (i+1 >= ELEMENTSOF(ins)) | |
60f067b4 | 349 | return -E2BIG; |
663996b3 MS |
350 | } |
351 | ||
352 | /* nothing matched, drop packet */ | |
353 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0); | |
354 | } | |
355 | ||
356 | /* matched, pass packet */ | |
357 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); | |
358 | ||
359 | /* install filter */ | |
60f067b4 | 360 | memzero(&filter, sizeof(filter)); |
663996b3 MS |
361 | filter.len = i; |
362 | filter.filter = ins; | |
363 | err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); | |
60f067b4 | 364 | return err < 0 ? -errno : 0; |
663996b3 MS |
365 | } |
366 | ||
367 | int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender) | |
368 | { | |
369 | udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid; | |
370 | return 0; | |
371 | } | |
372 | /** | |
373 | * udev_monitor_enable_receiving: | |
374 | * @udev_monitor: the monitor which should receive events | |
375 | * | |
376 | * Binds the @udev_monitor socket to the event source. | |
377 | * | |
378 | * Returns: 0 on success, otherwise a negative error value. | |
379 | */ | |
380 | _public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor) | |
381 | { | |
382 | int err = 0; | |
383 | const int on = 1; | |
384 | ||
663996b3 MS |
385 | udev_monitor_filter_update(udev_monitor); |
386 | ||
387 | if (!udev_monitor->bound) { | |
388 | err = bind(udev_monitor->sock, | |
389 | &udev_monitor->snl.sa, sizeof(struct sockaddr_nl)); | |
390 | if (err == 0) | |
391 | udev_monitor->bound = true; | |
392 | } | |
393 | ||
394 | if (err >= 0) { | |
395 | union sockaddr_union snl; | |
396 | socklen_t addrlen; | |
397 | ||
398 | /* | |
399 | * get the address the kernel has assigned us | |
400 | * it is usually, but not necessarily the pid | |
401 | */ | |
402 | addrlen = sizeof(struct sockaddr_nl); | |
403 | err = getsockname(udev_monitor->sock, &snl.sa, &addrlen); | |
404 | if (err == 0) | |
405 | udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid; | |
406 | } else { | |
f47781d8 | 407 | log_debug_errno(errno, "bind failed: %m"); |
60f067b4 | 408 | return -errno; |
663996b3 MS |
409 | } |
410 | ||
411 | /* enable receiving of sender credentials */ | |
5eef597e MP |
412 | err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)); |
413 | if (err < 0) | |
f47781d8 | 414 | log_debug_errno(errno, "setting SO_PASSCRED failed: %m"); |
5eef597e | 415 | |
663996b3 MS |
416 | return 0; |
417 | } | |
418 | ||
419 | /** | |
420 | * udev_monitor_set_receive_buffer_size: | |
421 | * @udev_monitor: the monitor which should receive events | |
422 | * @size: the size in bytes | |
423 | * | |
424 | * Set the size of the kernel socket buffer. This call needs the | |
425 | * appropriate privileges to succeed. | |
426 | * | |
427 | * Returns: 0 on success, otherwise -1 on error. | |
428 | */ | |
429 | _public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size) | |
430 | { | |
431 | if (udev_monitor == NULL) | |
60f067b4 | 432 | return -EINVAL; |
663996b3 MS |
433 | return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size)); |
434 | } | |
435 | ||
436 | int udev_monitor_disconnect(struct udev_monitor *udev_monitor) | |
437 | { | |
438 | int err; | |
439 | ||
440 | err = close(udev_monitor->sock); | |
441 | udev_monitor->sock = -1; | |
60f067b4 | 442 | return err < 0 ? -errno : 0; |
663996b3 MS |
443 | } |
444 | ||
445 | /** | |
446 | * udev_monitor_ref: | |
447 | * @udev_monitor: udev monitor | |
448 | * | |
449 | * Take a reference of a udev monitor. | |
450 | * | |
451 | * Returns: the passed udev monitor | |
452 | **/ | |
453 | _public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor) | |
454 | { | |
455 | if (udev_monitor == NULL) | |
456 | return NULL; | |
457 | udev_monitor->refcount++; | |
458 | return udev_monitor; | |
459 | } | |
460 | ||
461 | /** | |
462 | * udev_monitor_unref: | |
463 | * @udev_monitor: udev monitor | |
464 | * | |
465 | * Drop a reference of a udev monitor. If the refcount reaches zero, | |
466 | * the bound socket will be closed, and the resources of the monitor | |
467 | * will be released. | |
468 | * | |
60f067b4 | 469 | * Returns: #NULL |
663996b3 MS |
470 | **/ |
471 | _public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor) | |
472 | { | |
473 | if (udev_monitor == NULL) | |
474 | return NULL; | |
475 | udev_monitor->refcount--; | |
476 | if (udev_monitor->refcount > 0) | |
60f067b4 | 477 | return NULL; |
663996b3 MS |
478 | if (udev_monitor->sock >= 0) |
479 | close(udev_monitor->sock); | |
480 | udev_list_cleanup(&udev_monitor->filter_subsystem_list); | |
481 | udev_list_cleanup(&udev_monitor->filter_tag_list); | |
482 | free(udev_monitor); | |
483 | return NULL; | |
484 | } | |
485 | ||
486 | /** | |
487 | * udev_monitor_get_udev: | |
488 | * @udev_monitor: udev monitor | |
489 | * | |
490 | * Retrieve the udev library context the monitor was created with. | |
491 | * | |
492 | * Returns: the udev library context | |
493 | **/ | |
494 | _public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor) | |
495 | { | |
496 | if (udev_monitor == NULL) | |
497 | return NULL; | |
498 | return udev_monitor->udev; | |
499 | } | |
500 | ||
501 | /** | |
502 | * udev_monitor_get_fd: | |
503 | * @udev_monitor: udev monitor | |
504 | * | |
505 | * Retrieve the socket file descriptor associated with the monitor. | |
506 | * | |
507 | * Returns: the socket file descriptor | |
508 | **/ | |
509 | _public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor) | |
510 | { | |
511 | if (udev_monitor == NULL) | |
60f067b4 | 512 | return -EINVAL; |
663996b3 MS |
513 | return udev_monitor->sock; |
514 | } | |
515 | ||
516 | static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device) | |
517 | { | |
518 | struct udev_list_entry *list_entry; | |
519 | ||
520 | if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL) | |
521 | goto tag; | |
522 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) { | |
523 | const char *subsys = udev_list_entry_get_name(list_entry); | |
524 | const char *dsubsys = udev_device_get_subsystem(udev_device); | |
525 | const char *devtype; | |
526 | const char *ddevtype; | |
527 | ||
528 | if (!streq(dsubsys, subsys)) | |
529 | continue; | |
530 | ||
531 | devtype = udev_list_entry_get_value(list_entry); | |
532 | if (devtype == NULL) | |
533 | goto tag; | |
534 | ddevtype = udev_device_get_devtype(udev_device); | |
535 | if (ddevtype == NULL) | |
536 | continue; | |
537 | if (streq(ddevtype, devtype)) | |
538 | goto tag; | |
539 | } | |
540 | return 0; | |
541 | ||
542 | tag: | |
543 | if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL) | |
544 | return 1; | |
545 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) { | |
546 | const char *tag = udev_list_entry_get_name(list_entry); | |
547 | ||
548 | if (udev_device_has_tag(udev_device, tag)) | |
549 | return 1; | |
550 | } | |
551 | return 0; | |
552 | } | |
553 | ||
554 | /** | |
555 | * udev_monitor_receive_device: | |
556 | * @udev_monitor: udev monitor | |
557 | * | |
558 | * Receive data from the udev monitor socket, allocate a new udev | |
559 | * device, fill in the received data, and return the device. | |
560 | * | |
561 | * Only socket connections with uid=0 are accepted. | |
562 | * | |
563 | * The monitor socket is by default set to NONBLOCK. A variant of poll() on | |
564 | * the file descriptor returned by udev_monitor_get_fd() should to be used to | |
565 | * wake up when new devices arrive, or alternatively the file descriptor | |
566 | * switched into blocking mode. | |
567 | * | |
568 | * The initial refcount is 1, and needs to be decremented to | |
569 | * release the resources of the udev device. | |
570 | * | |
571 | * Returns: a new udev device, or #NULL, in case of an error | |
572 | **/ | |
573 | _public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor) | |
574 | { | |
575 | struct udev_device *udev_device; | |
576 | struct msghdr smsg; | |
577 | struct iovec iov; | |
578 | char cred_msg[CMSG_SPACE(sizeof(struct ucred))]; | |
579 | struct cmsghdr *cmsg; | |
580 | union sockaddr_union snl; | |
581 | struct ucred *cred; | |
e735f4d4 MP |
582 | union { |
583 | struct udev_monitor_netlink_header nlh; | |
584 | char raw[8192]; | |
585 | } buf; | |
663996b3 MS |
586 | ssize_t buflen; |
587 | ssize_t bufpos; | |
e735f4d4 | 588 | bool is_initialized = false; |
663996b3 MS |
589 | |
590 | retry: | |
591 | if (udev_monitor == NULL) | |
592 | return NULL; | |
593 | iov.iov_base = &buf; | |
594 | iov.iov_len = sizeof(buf); | |
60f067b4 | 595 | memzero(&smsg, sizeof(struct msghdr)); |
663996b3 MS |
596 | smsg.msg_iov = &iov; |
597 | smsg.msg_iovlen = 1; | |
598 | smsg.msg_control = cred_msg; | |
599 | smsg.msg_controllen = sizeof(cred_msg); | |
60f067b4 JS |
600 | smsg.msg_name = &snl; |
601 | smsg.msg_namelen = sizeof(snl); | |
663996b3 MS |
602 | |
603 | buflen = recvmsg(udev_monitor->sock, &smsg, 0); | |
604 | if (buflen < 0) { | |
605 | if (errno != EINTR) | |
f47781d8 | 606 | log_debug("unable to receive message"); |
663996b3 MS |
607 | return NULL; |
608 | } | |
609 | ||
e735f4d4 | 610 | if (buflen < 32 || (smsg.msg_flags & MSG_TRUNC)) { |
f47781d8 | 611 | log_debug("invalid message length"); |
663996b3 MS |
612 | return NULL; |
613 | } | |
614 | ||
60f067b4 JS |
615 | if (snl.nl.nl_groups == 0) { |
616 | /* unicast message, check if we trust the sender */ | |
617 | if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 || | |
618 | snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) { | |
f47781d8 | 619 | log_debug("unicast netlink message ignored"); |
60f067b4 JS |
620 | return NULL; |
621 | } | |
622 | } else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) { | |
623 | if (snl.nl.nl_pid > 0) { | |
e735f4d4 MP |
624 | log_debug("multicast kernel netlink message from PID %"PRIu32" ignored", |
625 | snl.nl.nl_pid); | |
60f067b4 | 626 | return NULL; |
663996b3 MS |
627 | } |
628 | } | |
629 | ||
630 | cmsg = CMSG_FIRSTHDR(&smsg); | |
631 | if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) { | |
f47781d8 | 632 | log_debug("no sender credentials received, message ignored"); |
663996b3 MS |
633 | return NULL; |
634 | } | |
635 | ||
636 | cred = (struct ucred *)CMSG_DATA(cmsg); | |
637 | if (cred->uid != 0) { | |
e735f4d4 | 638 | log_debug("sender uid="UID_FMT", message ignored", cred->uid); |
663996b3 MS |
639 | return NULL; |
640 | } | |
641 | ||
e735f4d4 | 642 | if (memcmp(buf.raw, "libudev", 8) == 0) { |
663996b3 | 643 | /* udev message needs proper version magic */ |
e735f4d4 | 644 | if (buf.nlh.magic != htonl(UDEV_MONITOR_MAGIC)) { |
f47781d8 | 645 | log_debug("unrecognized message signature (%x != %x)", |
e735f4d4 | 646 | buf.nlh.magic, htonl(UDEV_MONITOR_MAGIC)); |
663996b3 MS |
647 | return NULL; |
648 | } | |
e735f4d4 | 649 | if (buf.nlh.properties_off+32 > (size_t)buflen) { |
663996b3 | 650 | return NULL; |
60f067b4 JS |
651 | } |
652 | ||
e735f4d4 | 653 | bufpos = buf.nlh.properties_off; |
60f067b4 JS |
654 | |
655 | /* devices received from udev are always initialized */ | |
e735f4d4 | 656 | is_initialized = true; |
663996b3 MS |
657 | } else { |
658 | /* kernel message with header */ | |
e735f4d4 | 659 | bufpos = strlen(buf.raw) + 1; |
663996b3 | 660 | if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) { |
f47781d8 | 661 | log_debug("invalid message length"); |
663996b3 MS |
662 | return NULL; |
663 | } | |
664 | ||
665 | /* check message header */ | |
e735f4d4 | 666 | if (strstr(buf.raw, "@/") == NULL) { |
f47781d8 | 667 | log_debug("unrecognized message header"); |
663996b3 MS |
668 | return NULL; |
669 | } | |
670 | } | |
671 | ||
e735f4d4 MP |
672 | udev_device = udev_device_new_from_nulstr(udev_monitor->udev, &buf.raw[bufpos], buflen - bufpos); |
673 | if (!udev_device) | |
663996b3 | 674 | return NULL; |
e735f4d4 MP |
675 | |
676 | if (is_initialized) | |
677 | udev_device_set_is_initialized(udev_device); | |
663996b3 MS |
678 | |
679 | /* skip device, if it does not pass the current filter */ | |
680 | if (!passes_filter(udev_monitor, udev_device)) { | |
681 | struct pollfd pfd[1]; | |
682 | int rc; | |
683 | ||
684 | udev_device_unref(udev_device); | |
685 | ||
686 | /* if something is queued, get next device */ | |
687 | pfd[0].fd = udev_monitor->sock; | |
688 | pfd[0].events = POLLIN; | |
689 | rc = poll(pfd, 1, 0); | |
690 | if (rc > 0) | |
691 | goto retry; | |
692 | return NULL; | |
693 | } | |
694 | ||
695 | return udev_device; | |
696 | } | |
697 | ||
698 | int udev_monitor_send_device(struct udev_monitor *udev_monitor, | |
699 | struct udev_monitor *destination, struct udev_device *udev_device) | |
700 | { | |
701 | const char *buf; | |
702 | ssize_t blen; | |
703 | ssize_t count; | |
704 | struct msghdr smsg; | |
705 | struct iovec iov[2]; | |
706 | const char *val; | |
707 | struct udev_monitor_netlink_header nlh; | |
708 | struct udev_list_entry *list_entry; | |
709 | uint64_t tag_bloom_bits; | |
710 | ||
663996b3 MS |
711 | blen = udev_device_get_properties_monitor_buf(udev_device, &buf); |
712 | if (blen < 32) | |
713 | return -EINVAL; | |
714 | ||
715 | /* add versioned header */ | |
60f067b4 | 716 | memzero(&nlh, sizeof(struct udev_monitor_netlink_header)); |
663996b3 MS |
717 | memcpy(nlh.prefix, "libudev", 8); |
718 | nlh.magic = htonl(UDEV_MONITOR_MAGIC); | |
719 | nlh.header_size = sizeof(struct udev_monitor_netlink_header); | |
720 | val = udev_device_get_subsystem(udev_device); | |
721 | nlh.filter_subsystem_hash = htonl(util_string_hash32(val)); | |
722 | val = udev_device_get_devtype(udev_device); | |
723 | if (val != NULL) | |
724 | nlh.filter_devtype_hash = htonl(util_string_hash32(val)); | |
725 | iov[0].iov_base = &nlh; | |
726 | iov[0].iov_len = sizeof(struct udev_monitor_netlink_header); | |
727 | ||
728 | /* add tag bloom filter */ | |
729 | tag_bloom_bits = 0; | |
730 | udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device)) | |
731 | tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry)); | |
732 | if (tag_bloom_bits > 0) { | |
733 | nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32); | |
734 | nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff); | |
735 | } | |
736 | ||
737 | /* add properties list */ | |
738 | nlh.properties_off = iov[0].iov_len; | |
739 | nlh.properties_len = blen; | |
740 | iov[1].iov_base = (char *)buf; | |
741 | iov[1].iov_len = blen; | |
742 | ||
60f067b4 | 743 | memzero(&smsg, sizeof(struct msghdr)); |
663996b3 MS |
744 | smsg.msg_iov = iov; |
745 | smsg.msg_iovlen = 2; | |
746 | /* | |
747 | * Use custom address for target, or the default one. | |
748 | * | |
749 | * If we send to a multicast group, we will get | |
750 | * ECONNREFUSED, which is expected. | |
751 | */ | |
752 | if (destination != NULL) | |
753 | smsg.msg_name = &destination->snl; | |
754 | else | |
755 | smsg.msg_name = &udev_monitor->snl_destination; | |
756 | smsg.msg_namelen = sizeof(struct sockaddr_nl); | |
757 | count = sendmsg(udev_monitor->sock, &smsg, 0); | |
f47781d8 | 758 | log_debug("passed %zi bytes to netlink monitor %p", count, udev_monitor); |
663996b3 MS |
759 | return count; |
760 | } | |
761 | ||
762 | /** | |
763 | * udev_monitor_filter_add_match_subsystem_devtype: | |
764 | * @udev_monitor: the monitor | |
765 | * @subsystem: the subsystem value to match the incoming devices against | |
766 | * @devtype: the devtype value to match the incoming devices against | |
767 | * | |
768 | * This filter is efficiently executed inside the kernel, and libudev subscribers | |
769 | * will usually not be woken up for devices which do not match. | |
770 | * | |
771 | * The filter must be installed before the monitor is switched to listening mode. | |
772 | * | |
773 | * Returns: 0 on success, otherwise a negative error value. | |
774 | */ | |
775 | _public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype) | |
776 | { | |
777 | if (udev_monitor == NULL) | |
778 | return -EINVAL; | |
779 | if (subsystem == NULL) | |
780 | return -EINVAL; | |
781 | if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL) | |
782 | return -ENOMEM; | |
783 | return 0; | |
784 | } | |
785 | ||
786 | /** | |
787 | * udev_monitor_filter_add_match_tag: | |
788 | * @udev_monitor: the monitor | |
789 | * @tag: the name of a tag | |
790 | * | |
791 | * This filter is efficiently executed inside the kernel, and libudev subscribers | |
792 | * will usually not be woken up for devices which do not match. | |
793 | * | |
794 | * The filter must be installed before the monitor is switched to listening mode. | |
795 | * | |
796 | * Returns: 0 on success, otherwise a negative error value. | |
797 | */ | |
798 | _public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag) | |
799 | { | |
800 | if (udev_monitor == NULL) | |
801 | return -EINVAL; | |
802 | if (tag == NULL) | |
803 | return -EINVAL; | |
804 | if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL) | |
805 | return -ENOMEM; | |
806 | return 0; | |
807 | } | |
808 | ||
809 | /** | |
810 | * udev_monitor_filter_remove: | |
811 | * @udev_monitor: monitor | |
812 | * | |
813 | * Remove all filters from monitor. | |
814 | * | |
815 | * Returns: 0 on success, otherwise a negative error value. | |
816 | */ | |
817 | _public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor) | |
818 | { | |
819 | static struct sock_fprog filter = { 0, NULL }; | |
820 | ||
821 | udev_list_cleanup(&udev_monitor->filter_subsystem_list); | |
822 | return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); | |
823 | } |