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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> | |
27 | #include <sys/poll.h> | |
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 | ||
112 | union file_handle_union h = { | |
113 | .handle.handle_bytes = MAX_HANDLE_SZ | |
114 | }; | |
115 | ||
116 | _cleanup_fclose_ FILE *f = NULL; | |
117 | char line[LINE_MAX], *e; | |
118 | int mount_id; | |
119 | int r; | |
120 | ||
121 | r = name_to_handle_at(AT_FDCWD, "/dev", &h.handle, &mount_id, 0); | |
122 | if (r < 0) { | |
123 | if (errno != EOPNOTSUPP) | |
f47781d8 | 124 | log_debug_errno(errno, "name_to_handle_at on /dev: %m"); |
60f067b4 JS |
125 | return false; |
126 | } | |
127 | ||
128 | f = fopen("/proc/self/mountinfo", "re"); | |
129 | if (!f) | |
130 | return false; | |
131 | ||
132 | FOREACH_LINE(line, f, return false) { | |
133 | int mid; | |
134 | ||
135 | if (sscanf(line, "%i", &mid) != 1) | |
136 | continue; | |
137 | ||
138 | if (mid != mount_id) | |
139 | continue; | |
140 | ||
141 | e = strstr(line, " - "); | |
142 | if (!e) | |
143 | continue; | |
144 | ||
145 | /* accept any name that starts with the currently expected type */ | |
146 | if (startswith(e + 3, "devtmpfs")) | |
147 | return true; | |
148 | } | |
149 | ||
150 | return false; | |
151 | } | |
152 | ||
663996b3 MS |
153 | struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd) |
154 | { | |
155 | struct udev_monitor *udev_monitor; | |
156 | unsigned int group; | |
157 | ||
158 | if (udev == NULL) | |
159 | return NULL; | |
160 | ||
161 | if (name == NULL) | |
162 | group = UDEV_MONITOR_NONE; | |
60f067b4 JS |
163 | else if (streq(name, "udev")) { |
164 | /* | |
165 | * We do not support subscribing to uevents if no instance of | |
166 | * udev is running. Uevents would otherwise broadcast the | |
167 | * processing data of the host into containers, which is not | |
168 | * desired. | |
169 | * | |
170 | * Containers will currently not get any udev uevents, until | |
171 | * a supporting infrastructure is available. | |
172 | * | |
173 | * We do not set a netlink multicast group here, so the socket | |
174 | * will not receive any messages. | |
175 | */ | |
176 | if (access("/run/udev/control", F_OK) < 0 && !udev_has_devtmpfs(udev)) { | |
f47781d8 | 177 | log_debug("the udev service seems not to be active, disable the monitor"); |
60f067b4 JS |
178 | group = UDEV_MONITOR_NONE; |
179 | } else | |
180 | group = UDEV_MONITOR_UDEV; | |
181 | } else if (streq(name, "kernel")) | |
663996b3 MS |
182 | group = UDEV_MONITOR_KERNEL; |
183 | else | |
184 | return NULL; | |
185 | ||
186 | udev_monitor = udev_monitor_new(udev); | |
187 | if (udev_monitor == NULL) | |
188 | return NULL; | |
189 | ||
190 | if (fd < 0) { | |
191 | udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT); | |
192 | if (udev_monitor->sock == -1) { | |
f47781d8 | 193 | log_debug_errno(errno, "error getting socket: %m"); |
663996b3 MS |
194 | free(udev_monitor); |
195 | return NULL; | |
196 | } | |
197 | } else { | |
198 | udev_monitor->bound = true; | |
199 | udev_monitor->sock = fd; | |
200 | } | |
201 | ||
202 | udev_monitor->snl.nl.nl_family = AF_NETLINK; | |
203 | udev_monitor->snl.nl.nl_groups = group; | |
204 | ||
205 | /* default destination for sending */ | |
206 | udev_monitor->snl_destination.nl.nl_family = AF_NETLINK; | |
207 | udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV; | |
208 | ||
209 | return udev_monitor; | |
210 | } | |
211 | ||
212 | /** | |
213 | * udev_monitor_new_from_netlink: | |
214 | * @udev: udev library context | |
215 | * @name: name of event source | |
216 | * | |
217 | * Create new udev monitor and connect to a specified event | |
218 | * source. Valid sources identifiers are "udev" and "kernel". | |
219 | * | |
220 | * Applications should usually not connect directly to the | |
221 | * "kernel" events, because the devices might not be useable | |
222 | * at that time, before udev has configured them, and created | |
223 | * device nodes. Accessing devices at the same time as udev, | |
224 | * might result in unpredictable behavior. The "udev" events | |
225 | * are sent out after udev has finished its event processing, | |
226 | * all rules have been processed, and needed device nodes are | |
227 | * created. | |
228 | * | |
229 | * The initial refcount is 1, and needs to be decremented to | |
230 | * release the resources of the udev monitor. | |
231 | * | |
232 | * Returns: a new udev monitor, or #NULL, in case of an error | |
233 | **/ | |
234 | _public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name) | |
235 | { | |
236 | return udev_monitor_new_from_netlink_fd(udev, name, -1); | |
237 | } | |
238 | ||
239 | static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i, | |
240 | unsigned short code, unsigned int data) | |
241 | { | |
242 | struct sock_filter *ins = &inss[*i]; | |
243 | ||
244 | ins->code = code; | |
245 | ins->k = data; | |
246 | (*i)++; | |
247 | } | |
248 | ||
249 | static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i, | |
250 | unsigned short code, unsigned int data, | |
251 | unsigned short jt, unsigned short jf) | |
252 | { | |
253 | struct sock_filter *ins = &inss[*i]; | |
254 | ||
255 | ins->code = code; | |
256 | ins->jt = jt; | |
257 | ins->jf = jf; | |
258 | ins->k = data; | |
259 | (*i)++; | |
260 | } | |
261 | ||
262 | /** | |
263 | * udev_monitor_filter_update: | |
264 | * @udev_monitor: monitor | |
265 | * | |
266 | * Update the installed socket filter. This is only needed, | |
267 | * if the filter was removed or changed. | |
268 | * | |
269 | * Returns: 0 on success, otherwise a negative error value. | |
270 | */ | |
271 | _public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor) | |
272 | { | |
273 | struct sock_filter ins[512]; | |
274 | struct sock_fprog filter; | |
275 | unsigned int i; | |
276 | struct udev_list_entry *list_entry; | |
277 | int err; | |
278 | ||
279 | if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL && | |
280 | udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL) | |
281 | return 0; | |
282 | ||
60f067b4 | 283 | memzero(ins, sizeof(ins)); |
663996b3 MS |
284 | i = 0; |
285 | ||
286 | /* load magic in A */ | |
287 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic)); | |
288 | /* jump if magic matches */ | |
289 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0); | |
290 | /* wrong magic, pass packet */ | |
291 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); | |
292 | ||
293 | if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) { | |
294 | int tag_matches; | |
295 | ||
296 | /* count tag matches, to calculate end of tag match block */ | |
297 | tag_matches = 0; | |
298 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) | |
299 | tag_matches++; | |
300 | ||
301 | /* add all tags matches */ | |
302 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) { | |
303 | uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry)); | |
304 | uint32_t tag_bloom_hi = tag_bloom_bits >> 32; | |
305 | uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff; | |
306 | ||
307 | /* load device bloom bits in A */ | |
308 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi)); | |
309 | /* clear bits (tag bits & bloom bits) */ | |
310 | bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi); | |
311 | /* jump to next tag if it does not match */ | |
312 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3); | |
313 | ||
314 | /* load device bloom bits in A */ | |
315 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo)); | |
316 | /* clear bits (tag bits & bloom bits) */ | |
317 | bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo); | |
318 | /* jump behind end of tag match block if tag matches */ | |
319 | tag_matches--; | |
320 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0); | |
321 | } | |
322 | ||
323 | /* nothing matched, drop packet */ | |
324 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0); | |
325 | } | |
326 | ||
327 | /* add all subsystem matches */ | |
328 | if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) { | |
329 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) { | |
330 | unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry)); | |
331 | ||
332 | /* load device subsystem value in A */ | |
333 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash)); | |
334 | if (udev_list_entry_get_value(list_entry) == NULL) { | |
335 | /* jump if subsystem does not match */ | |
336 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1); | |
337 | } else { | |
338 | /* jump if subsystem does not match */ | |
339 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3); | |
340 | ||
341 | /* load device devtype value in A */ | |
342 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash)); | |
343 | /* jump if value does not match */ | |
344 | hash = util_string_hash32(udev_list_entry_get_value(list_entry)); | |
345 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1); | |
346 | } | |
347 | ||
348 | /* matched, pass packet */ | |
349 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); | |
350 | ||
351 | if (i+1 >= ELEMENTSOF(ins)) | |
60f067b4 | 352 | return -E2BIG; |
663996b3 MS |
353 | } |
354 | ||
355 | /* nothing matched, drop packet */ | |
356 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0); | |
357 | } | |
358 | ||
359 | /* matched, pass packet */ | |
360 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); | |
361 | ||
362 | /* install filter */ | |
60f067b4 | 363 | memzero(&filter, sizeof(filter)); |
663996b3 MS |
364 | filter.len = i; |
365 | filter.filter = ins; | |
366 | err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); | |
60f067b4 | 367 | return err < 0 ? -errno : 0; |
663996b3 MS |
368 | } |
369 | ||
370 | int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender) | |
371 | { | |
372 | udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid; | |
373 | return 0; | |
374 | } | |
375 | /** | |
376 | * udev_monitor_enable_receiving: | |
377 | * @udev_monitor: the monitor which should receive events | |
378 | * | |
379 | * Binds the @udev_monitor socket to the event source. | |
380 | * | |
381 | * Returns: 0 on success, otherwise a negative error value. | |
382 | */ | |
383 | _public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor) | |
384 | { | |
385 | int err = 0; | |
386 | const int on = 1; | |
387 | ||
663996b3 MS |
388 | udev_monitor_filter_update(udev_monitor); |
389 | ||
390 | if (!udev_monitor->bound) { | |
391 | err = bind(udev_monitor->sock, | |
392 | &udev_monitor->snl.sa, sizeof(struct sockaddr_nl)); | |
393 | if (err == 0) | |
394 | udev_monitor->bound = true; | |
395 | } | |
396 | ||
397 | if (err >= 0) { | |
398 | union sockaddr_union snl; | |
399 | socklen_t addrlen; | |
400 | ||
401 | /* | |
402 | * get the address the kernel has assigned us | |
403 | * it is usually, but not necessarily the pid | |
404 | */ | |
405 | addrlen = sizeof(struct sockaddr_nl); | |
406 | err = getsockname(udev_monitor->sock, &snl.sa, &addrlen); | |
407 | if (err == 0) | |
408 | udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid; | |
409 | } else { | |
f47781d8 | 410 | log_debug_errno(errno, "bind failed: %m"); |
60f067b4 | 411 | return -errno; |
663996b3 MS |
412 | } |
413 | ||
414 | /* enable receiving of sender credentials */ | |
5eef597e MP |
415 | err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)); |
416 | if (err < 0) | |
f47781d8 | 417 | log_debug_errno(errno, "setting SO_PASSCRED failed: %m"); |
5eef597e | 418 | |
663996b3 MS |
419 | return 0; |
420 | } | |
421 | ||
422 | /** | |
423 | * udev_monitor_set_receive_buffer_size: | |
424 | * @udev_monitor: the monitor which should receive events | |
425 | * @size: the size in bytes | |
426 | * | |
427 | * Set the size of the kernel socket buffer. This call needs the | |
428 | * appropriate privileges to succeed. | |
429 | * | |
430 | * Returns: 0 on success, otherwise -1 on error. | |
431 | */ | |
432 | _public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size) | |
433 | { | |
434 | if (udev_monitor == NULL) | |
60f067b4 | 435 | return -EINVAL; |
663996b3 MS |
436 | return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size)); |
437 | } | |
438 | ||
439 | int udev_monitor_disconnect(struct udev_monitor *udev_monitor) | |
440 | { | |
441 | int err; | |
442 | ||
443 | err = close(udev_monitor->sock); | |
444 | udev_monitor->sock = -1; | |
60f067b4 | 445 | return err < 0 ? -errno : 0; |
663996b3 MS |
446 | } |
447 | ||
448 | /** | |
449 | * udev_monitor_ref: | |
450 | * @udev_monitor: udev monitor | |
451 | * | |
452 | * Take a reference of a udev monitor. | |
453 | * | |
454 | * Returns: the passed udev monitor | |
455 | **/ | |
456 | _public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor) | |
457 | { | |
458 | if (udev_monitor == NULL) | |
459 | return NULL; | |
460 | udev_monitor->refcount++; | |
461 | return udev_monitor; | |
462 | } | |
463 | ||
464 | /** | |
465 | * udev_monitor_unref: | |
466 | * @udev_monitor: udev monitor | |
467 | * | |
468 | * Drop a reference of a udev monitor. If the refcount reaches zero, | |
469 | * the bound socket will be closed, and the resources of the monitor | |
470 | * will be released. | |
471 | * | |
60f067b4 | 472 | * Returns: #NULL |
663996b3 MS |
473 | **/ |
474 | _public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor) | |
475 | { | |
476 | if (udev_monitor == NULL) | |
477 | return NULL; | |
478 | udev_monitor->refcount--; | |
479 | if (udev_monitor->refcount > 0) | |
60f067b4 | 480 | return NULL; |
663996b3 MS |
481 | if (udev_monitor->sock >= 0) |
482 | close(udev_monitor->sock); | |
483 | udev_list_cleanup(&udev_monitor->filter_subsystem_list); | |
484 | udev_list_cleanup(&udev_monitor->filter_tag_list); | |
485 | free(udev_monitor); | |
486 | return NULL; | |
487 | } | |
488 | ||
489 | /** | |
490 | * udev_monitor_get_udev: | |
491 | * @udev_monitor: udev monitor | |
492 | * | |
493 | * Retrieve the udev library context the monitor was created with. | |
494 | * | |
495 | * Returns: the udev library context | |
496 | **/ | |
497 | _public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor) | |
498 | { | |
499 | if (udev_monitor == NULL) | |
500 | return NULL; | |
501 | return udev_monitor->udev; | |
502 | } | |
503 | ||
504 | /** | |
505 | * udev_monitor_get_fd: | |
506 | * @udev_monitor: udev monitor | |
507 | * | |
508 | * Retrieve the socket file descriptor associated with the monitor. | |
509 | * | |
510 | * Returns: the socket file descriptor | |
511 | **/ | |
512 | _public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor) | |
513 | { | |
514 | if (udev_monitor == NULL) | |
60f067b4 | 515 | return -EINVAL; |
663996b3 MS |
516 | return udev_monitor->sock; |
517 | } | |
518 | ||
519 | static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device) | |
520 | { | |
521 | struct udev_list_entry *list_entry; | |
522 | ||
523 | if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL) | |
524 | goto tag; | |
525 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) { | |
526 | const char *subsys = udev_list_entry_get_name(list_entry); | |
527 | const char *dsubsys = udev_device_get_subsystem(udev_device); | |
528 | const char *devtype; | |
529 | const char *ddevtype; | |
530 | ||
531 | if (!streq(dsubsys, subsys)) | |
532 | continue; | |
533 | ||
534 | devtype = udev_list_entry_get_value(list_entry); | |
535 | if (devtype == NULL) | |
536 | goto tag; | |
537 | ddevtype = udev_device_get_devtype(udev_device); | |
538 | if (ddevtype == NULL) | |
539 | continue; | |
540 | if (streq(ddevtype, devtype)) | |
541 | goto tag; | |
542 | } | |
543 | return 0; | |
544 | ||
545 | tag: | |
546 | if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL) | |
547 | return 1; | |
548 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) { | |
549 | const char *tag = udev_list_entry_get_name(list_entry); | |
550 | ||
551 | if (udev_device_has_tag(udev_device, tag)) | |
552 | return 1; | |
553 | } | |
554 | return 0; | |
555 | } | |
556 | ||
557 | /** | |
558 | * udev_monitor_receive_device: | |
559 | * @udev_monitor: udev monitor | |
560 | * | |
561 | * Receive data from the udev monitor socket, allocate a new udev | |
562 | * device, fill in the received data, and return the device. | |
563 | * | |
564 | * Only socket connections with uid=0 are accepted. | |
565 | * | |
566 | * The monitor socket is by default set to NONBLOCK. A variant of poll() on | |
567 | * the file descriptor returned by udev_monitor_get_fd() should to be used to | |
568 | * wake up when new devices arrive, or alternatively the file descriptor | |
569 | * switched into blocking mode. | |
570 | * | |
571 | * The initial refcount is 1, and needs to be decremented to | |
572 | * release the resources of the udev device. | |
573 | * | |
574 | * Returns: a new udev device, or #NULL, in case of an error | |
575 | **/ | |
576 | _public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor) | |
577 | { | |
578 | struct udev_device *udev_device; | |
579 | struct msghdr smsg; | |
580 | struct iovec iov; | |
581 | char cred_msg[CMSG_SPACE(sizeof(struct ucred))]; | |
582 | struct cmsghdr *cmsg; | |
583 | union sockaddr_union snl; | |
584 | struct ucred *cred; | |
585 | char buf[8192]; | |
586 | ssize_t buflen; | |
587 | ssize_t bufpos; | |
663996b3 MS |
588 | |
589 | retry: | |
590 | if (udev_monitor == NULL) | |
591 | return NULL; | |
592 | iov.iov_base = &buf; | |
593 | iov.iov_len = sizeof(buf); | |
60f067b4 | 594 | memzero(&smsg, sizeof(struct msghdr)); |
663996b3 MS |
595 | smsg.msg_iov = &iov; |
596 | smsg.msg_iovlen = 1; | |
597 | smsg.msg_control = cred_msg; | |
598 | smsg.msg_controllen = sizeof(cred_msg); | |
60f067b4 JS |
599 | smsg.msg_name = &snl; |
600 | smsg.msg_namelen = sizeof(snl); | |
663996b3 MS |
601 | |
602 | buflen = recvmsg(udev_monitor->sock, &smsg, 0); | |
603 | if (buflen < 0) { | |
604 | if (errno != EINTR) | |
f47781d8 | 605 | log_debug("unable to receive message"); |
663996b3 MS |
606 | return NULL; |
607 | } | |
608 | ||
609 | if (buflen < 32 || (size_t)buflen >= sizeof(buf)) { | |
f47781d8 | 610 | log_debug("invalid message length"); |
663996b3 MS |
611 | return NULL; |
612 | } | |
613 | ||
60f067b4 JS |
614 | if (snl.nl.nl_groups == 0) { |
615 | /* unicast message, check if we trust the sender */ | |
616 | if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 || | |
617 | snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) { | |
f47781d8 | 618 | log_debug("unicast netlink message ignored"); |
60f067b4 JS |
619 | return NULL; |
620 | } | |
621 | } else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) { | |
622 | if (snl.nl.nl_pid > 0) { | |
f47781d8 | 623 | log_debug("multicast kernel netlink message from pid %d ignored", |
60f067b4 JS |
624 | snl.nl.nl_pid); |
625 | return NULL; | |
663996b3 MS |
626 | } |
627 | } | |
628 | ||
629 | cmsg = CMSG_FIRSTHDR(&smsg); | |
630 | if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) { | |
f47781d8 | 631 | log_debug("no sender credentials received, message ignored"); |
663996b3 MS |
632 | return NULL; |
633 | } | |
634 | ||
635 | cred = (struct ucred *)CMSG_DATA(cmsg); | |
636 | if (cred->uid != 0) { | |
f47781d8 | 637 | log_debug("sender uid=%d, message ignored", cred->uid); |
663996b3 MS |
638 | return NULL; |
639 | } | |
640 | ||
60f067b4 JS |
641 | udev_device = udev_device_new(udev_monitor->udev); |
642 | if (udev_device == NULL) | |
643 | return NULL; | |
644 | ||
663996b3 | 645 | if (memcmp(buf, "libudev", 8) == 0) { |
60f067b4 JS |
646 | struct udev_monitor_netlink_header *nlh; |
647 | ||
663996b3 MS |
648 | /* udev message needs proper version magic */ |
649 | nlh = (struct udev_monitor_netlink_header *) buf; | |
650 | if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) { | |
f47781d8 | 651 | log_debug("unrecognized message signature (%x != %x)", |
60f067b4 JS |
652 | nlh->magic, htonl(UDEV_MONITOR_MAGIC)); |
653 | udev_device_unref(udev_device); | |
663996b3 MS |
654 | return NULL; |
655 | } | |
60f067b4 JS |
656 | if (nlh->properties_off+32 > (size_t)buflen) { |
657 | udev_device_unref(udev_device); | |
663996b3 | 658 | return NULL; |
60f067b4 JS |
659 | } |
660 | ||
663996b3 | 661 | bufpos = nlh->properties_off; |
60f067b4 JS |
662 | |
663 | /* devices received from udev are always initialized */ | |
664 | udev_device_set_is_initialized(udev_device); | |
663996b3 MS |
665 | } else { |
666 | /* kernel message with header */ | |
667 | bufpos = strlen(buf) + 1; | |
668 | if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) { | |
f47781d8 | 669 | log_debug("invalid message length"); |
60f067b4 | 670 | udev_device_unref(udev_device); |
663996b3 MS |
671 | return NULL; |
672 | } | |
673 | ||
674 | /* check message header */ | |
675 | if (strstr(buf, "@/") == NULL) { | |
f47781d8 | 676 | log_debug("unrecognized message header"); |
60f067b4 | 677 | udev_device_unref(udev_device); |
663996b3 MS |
678 | return NULL; |
679 | } | |
680 | } | |
681 | ||
663996b3 MS |
682 | udev_device_set_info_loaded(udev_device); |
683 | ||
684 | while (bufpos < buflen) { | |
685 | char *key; | |
686 | size_t keylen; | |
687 | ||
688 | key = &buf[bufpos]; | |
689 | keylen = strlen(key); | |
690 | if (keylen == 0) | |
691 | break; | |
692 | bufpos += keylen + 1; | |
693 | udev_device_add_property_from_string_parse(udev_device, key); | |
694 | } | |
695 | ||
696 | if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) { | |
f47781d8 | 697 | log_debug("missing values, invalid device"); |
663996b3 MS |
698 | udev_device_unref(udev_device); |
699 | return NULL; | |
700 | } | |
701 | ||
702 | /* skip device, if it does not pass the current filter */ | |
703 | if (!passes_filter(udev_monitor, udev_device)) { | |
704 | struct pollfd pfd[1]; | |
705 | int rc; | |
706 | ||
707 | udev_device_unref(udev_device); | |
708 | ||
709 | /* if something is queued, get next device */ | |
710 | pfd[0].fd = udev_monitor->sock; | |
711 | pfd[0].events = POLLIN; | |
712 | rc = poll(pfd, 1, 0); | |
713 | if (rc > 0) | |
714 | goto retry; | |
715 | return NULL; | |
716 | } | |
717 | ||
718 | return udev_device; | |
719 | } | |
720 | ||
721 | int udev_monitor_send_device(struct udev_monitor *udev_monitor, | |
722 | struct udev_monitor *destination, struct udev_device *udev_device) | |
723 | { | |
724 | const char *buf; | |
725 | ssize_t blen; | |
726 | ssize_t count; | |
727 | struct msghdr smsg; | |
728 | struct iovec iov[2]; | |
729 | const char *val; | |
730 | struct udev_monitor_netlink_header nlh; | |
731 | struct udev_list_entry *list_entry; | |
732 | uint64_t tag_bloom_bits; | |
733 | ||
663996b3 MS |
734 | blen = udev_device_get_properties_monitor_buf(udev_device, &buf); |
735 | if (blen < 32) | |
736 | return -EINVAL; | |
737 | ||
738 | /* add versioned header */ | |
60f067b4 | 739 | memzero(&nlh, sizeof(struct udev_monitor_netlink_header)); |
663996b3 MS |
740 | memcpy(nlh.prefix, "libudev", 8); |
741 | nlh.magic = htonl(UDEV_MONITOR_MAGIC); | |
742 | nlh.header_size = sizeof(struct udev_monitor_netlink_header); | |
743 | val = udev_device_get_subsystem(udev_device); | |
744 | nlh.filter_subsystem_hash = htonl(util_string_hash32(val)); | |
745 | val = udev_device_get_devtype(udev_device); | |
746 | if (val != NULL) | |
747 | nlh.filter_devtype_hash = htonl(util_string_hash32(val)); | |
748 | iov[0].iov_base = &nlh; | |
749 | iov[0].iov_len = sizeof(struct udev_monitor_netlink_header); | |
750 | ||
751 | /* add tag bloom filter */ | |
752 | tag_bloom_bits = 0; | |
753 | udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device)) | |
754 | tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry)); | |
755 | if (tag_bloom_bits > 0) { | |
756 | nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32); | |
757 | nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff); | |
758 | } | |
759 | ||
760 | /* add properties list */ | |
761 | nlh.properties_off = iov[0].iov_len; | |
762 | nlh.properties_len = blen; | |
763 | iov[1].iov_base = (char *)buf; | |
764 | iov[1].iov_len = blen; | |
765 | ||
60f067b4 | 766 | memzero(&smsg, sizeof(struct msghdr)); |
663996b3 MS |
767 | smsg.msg_iov = iov; |
768 | smsg.msg_iovlen = 2; | |
769 | /* | |
770 | * Use custom address for target, or the default one. | |
771 | * | |
772 | * If we send to a multicast group, we will get | |
773 | * ECONNREFUSED, which is expected. | |
774 | */ | |
775 | if (destination != NULL) | |
776 | smsg.msg_name = &destination->snl; | |
777 | else | |
778 | smsg.msg_name = &udev_monitor->snl_destination; | |
779 | smsg.msg_namelen = sizeof(struct sockaddr_nl); | |
780 | count = sendmsg(udev_monitor->sock, &smsg, 0); | |
f47781d8 | 781 | log_debug("passed %zi bytes to netlink monitor %p", count, udev_monitor); |
663996b3 MS |
782 | return count; |
783 | } | |
784 | ||
785 | /** | |
786 | * udev_monitor_filter_add_match_subsystem_devtype: | |
787 | * @udev_monitor: the monitor | |
788 | * @subsystem: the subsystem value to match the incoming devices against | |
789 | * @devtype: the devtype value to match the incoming devices against | |
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_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype) | |
799 | { | |
800 | if (udev_monitor == NULL) | |
801 | return -EINVAL; | |
802 | if (subsystem == NULL) | |
803 | return -EINVAL; | |
804 | if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL) | |
805 | return -ENOMEM; | |
806 | return 0; | |
807 | } | |
808 | ||
809 | /** | |
810 | * udev_monitor_filter_add_match_tag: | |
811 | * @udev_monitor: the monitor | |
812 | * @tag: the name of a tag | |
813 | * | |
814 | * This filter is efficiently executed inside the kernel, and libudev subscribers | |
815 | * will usually not be woken up for devices which do not match. | |
816 | * | |
817 | * The filter must be installed before the monitor is switched to listening mode. | |
818 | * | |
819 | * Returns: 0 on success, otherwise a negative error value. | |
820 | */ | |
821 | _public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag) | |
822 | { | |
823 | if (udev_monitor == NULL) | |
824 | return -EINVAL; | |
825 | if (tag == NULL) | |
826 | return -EINVAL; | |
827 | if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL) | |
828 | return -ENOMEM; | |
829 | return 0; | |
830 | } | |
831 | ||
832 | /** | |
833 | * udev_monitor_filter_remove: | |
834 | * @udev_monitor: monitor | |
835 | * | |
836 | * Remove all filters from monitor. | |
837 | * | |
838 | * Returns: 0 on success, otherwise a negative error value. | |
839 | */ | |
840 | _public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor) | |
841 | { | |
842 | static struct sock_fprog filter = { 0, NULL }; | |
843 | ||
844 | udev_list_cleanup(&udev_monitor->filter_subsystem_list); | |
845 | return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); | |
846 | } |