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88a6477e KS |
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 | ***/ | |
ba6929f6 | 19 | |
ba6929f6 KS |
20 | #include <stdio.h> |
21 | #include <stdlib.h> | |
22 | #include <stddef.h> | |
23 | #include <unistd.h> | |
24 | #include <errno.h> | |
25 | #include <string.h> | |
0a6f50c0 | 26 | #include <poll.h> |
ba6929f6 | 27 | #include <sys/socket.h> |
1c7047ea | 28 | #include <linux/netlink.h> |
e14bdd88 | 29 | #include <linux/filter.h> |
ba6929f6 KS |
30 | |
31 | #include "libudev.h" | |
32 | #include "libudev-private.h" | |
b49d9b50 | 33 | #include "socket-util.h" |
df32a1ca | 34 | #include "missing.h" |
6482f626 | 35 | #include "formats-util.h" |
ba6929f6 | 36 | |
ce1d6d7f KS |
37 | /** |
38 | * SECTION:libudev-monitor | |
39 | * @short_description: device event source | |
40 | * | |
41 | * Connects to a device event source. | |
42 | */ | |
43 | ||
ce1d6d7f KS |
44 | /** |
45 | * udev_monitor: | |
46 | * | |
50579295 | 47 | * Opaque object handling an event source. |
ce1d6d7f | 48 | */ |
ba6929f6 | 49 | struct udev_monitor { |
912541b0 KS |
50 | struct udev *udev; |
51 | int refcount; | |
52 | int sock; | |
b49d9b50 KS |
53 | union sockaddr_union snl; |
54 | union sockaddr_union snl_trusted_sender; | |
55 | union sockaddr_union snl_destination; | |
912541b0 KS |
56 | socklen_t addrlen; |
57 | struct udev_list filter_subsystem_list; | |
58 | struct udev_list filter_tag_list; | |
59 | bool bound; | |
ba6929f6 KS |
60 | }; |
61 | ||
f2b93744 | 62 | enum udev_monitor_netlink_group { |
912541b0 KS |
63 | UDEV_MONITOR_NONE, |
64 | UDEV_MONITOR_KERNEL, | |
65 | UDEV_MONITOR_UDEV, | |
f2b93744 KS |
66 | }; |
67 | ||
912541b0 | 68 | #define UDEV_MONITOR_MAGIC 0xfeedcafe |
e14bdd88 | 69 | struct udev_monitor_netlink_header { |
912541b0 KS |
70 | /* "libudev" prefix to distinguish libudev and kernel messages */ |
71 | char prefix[8]; | |
72 | /* | |
73 | * magic to protect against daemon <-> library message format mismatch | |
74 | * used in the kernel from socket filter rules; needs to be stored in network order | |
75 | */ | |
76 | unsigned int magic; | |
77 | /* total length of header structure known to the sender */ | |
78 | unsigned int header_size; | |
79 | /* properties string buffer */ | |
80 | unsigned int properties_off; | |
81 | unsigned int properties_len; | |
82 | /* | |
83 | * hashes of primary device properties strings, to let libudev subscribers | |
84 | * use in-kernel socket filters; values need to be stored in network order | |
85 | */ | |
86 | unsigned int filter_subsystem_hash; | |
87 | unsigned int filter_devtype_hash; | |
88 | unsigned int filter_tag_bloom_hi; | |
89 | unsigned int filter_tag_bloom_lo; | |
e14bdd88 KS |
90 | }; |
91 | ||
92 | static struct udev_monitor *udev_monitor_new(struct udev *udev) | |
93 | { | |
912541b0 KS |
94 | struct udev_monitor *udev_monitor; |
95 | ||
955d98c9 | 96 | udev_monitor = new0(struct udev_monitor, 1); |
912541b0 KS |
97 | if (udev_monitor == NULL) |
98 | return NULL; | |
99 | udev_monitor->refcount = 1; | |
100 | udev_monitor->udev = udev; | |
101 | udev_list_init(udev, &udev_monitor->filter_subsystem_list, false); | |
102 | udev_list_init(udev, &udev_monitor->filter_tag_list, true); | |
103 | return udev_monitor; | |
e14bdd88 KS |
104 | } |
105 | ||
df32a1ca KS |
106 | /* we consider udev running when /dev is on devtmpfs */ |
107 | static bool udev_has_devtmpfs(struct udev *udev) { | |
21749924 | 108 | |
2695c5c4 | 109 | union file_handle_union h = FILE_HANDLE_INIT; |
df32a1ca KS |
110 | _cleanup_fclose_ FILE *f = NULL; |
111 | char line[LINE_MAX], *e; | |
21749924 | 112 | int mount_id; |
df32a1ca KS |
113 | int r; |
114 | ||
370c860f | 115 | r = name_to_handle_at(AT_FDCWD, "/dev", &h.handle, &mount_id, 0); |
e6c47472 ZJS |
116 | if (r < 0) { |
117 | if (errno != EOPNOTSUPP) | |
56f64d95 | 118 | log_debug_errno(errno, "name_to_handle_at on /dev: %m"); |
df32a1ca | 119 | return false; |
e6c47472 | 120 | } |
df32a1ca | 121 | |
df32a1ca KS |
122 | f = fopen("/proc/self/mountinfo", "re"); |
123 | if (!f) | |
124 | return false; | |
125 | ||
126 | FOREACH_LINE(line, f, return false) { | |
df32a1ca KS |
127 | int mid; |
128 | ||
129 | if (sscanf(line, "%i", &mid) != 1) | |
130 | continue; | |
131 | ||
132 | if (mid != mount_id) | |
133 | continue; | |
134 | ||
135 | e = strstr(line, " - "); | |
136 | if (!e) | |
137 | continue; | |
138 | ||
139 | /* accept any name that starts with the currently expected type */ | |
140 | if (startswith(e + 3, "devtmpfs")) | |
141 | return true; | |
142 | } | |
143 | ||
144 | return false; | |
145 | } | |
146 | ||
7459bcdc | 147 | struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd) |
1c7047ea | 148 | { |
912541b0 KS |
149 | struct udev_monitor *udev_monitor; |
150 | unsigned int group; | |
151 | ||
152 | if (udev == NULL) | |
153 | return NULL; | |
154 | ||
155 | if (name == NULL) | |
156 | group = UDEV_MONITOR_NONE; | |
e8a3b2dc KS |
157 | else if (streq(name, "udev")) { |
158 | /* | |
159 | * We do not support subscribing to uevents if no instance of | |
160 | * udev is running. Uevents would otherwise broadcast the | |
161 | * processing data of the host into containers, which is not | |
162 | * desired. | |
163 | * | |
164 | * Containers will currently not get any udev uevents, until | |
165 | * a supporting infrastructure is available. | |
166 | * | |
167 | * We do not set a netlink multicast group here, so the socket | |
168 | * will not receive any messages. | |
169 | */ | |
9ea28c55 | 170 | if (access("/run/udev/control", F_OK) < 0 && !udev_has_devtmpfs(udev)) { |
ff49bc32 | 171 | log_debug("the udev service seems not to be active, disable the monitor"); |
e8a3b2dc KS |
172 | group = UDEV_MONITOR_NONE; |
173 | } else | |
174 | group = UDEV_MONITOR_UDEV; | |
175 | } else if (streq(name, "kernel")) | |
912541b0 KS |
176 | group = UDEV_MONITOR_KERNEL; |
177 | else | |
178 | return NULL; | |
179 | ||
180 | udev_monitor = udev_monitor_new(udev); | |
181 | if (udev_monitor == NULL) | |
182 | return NULL; | |
183 | ||
184 | if (fd < 0) { | |
185 | udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT); | |
186 | if (udev_monitor->sock == -1) { | |
56f64d95 | 187 | log_debug_errno(errno, "error getting socket: %m"); |
912541b0 KS |
188 | free(udev_monitor); |
189 | return NULL; | |
190 | } | |
191 | } else { | |
192 | udev_monitor->bound = true; | |
193 | udev_monitor->sock = fd; | |
194 | } | |
195 | ||
b49d9b50 KS |
196 | udev_monitor->snl.nl.nl_family = AF_NETLINK; |
197 | udev_monitor->snl.nl.nl_groups = group; | |
912541b0 KS |
198 | |
199 | /* default destination for sending */ | |
b49d9b50 KS |
200 | udev_monitor->snl_destination.nl.nl_family = AF_NETLINK; |
201 | udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV; | |
912541b0 | 202 | |
912541b0 | 203 | return udev_monitor; |
1c7047ea KS |
204 | } |
205 | ||
7459bcdc KS |
206 | /** |
207 | * udev_monitor_new_from_netlink: | |
208 | * @udev: udev library context | |
209 | * @name: name of event source | |
210 | * | |
211 | * Create new udev monitor and connect to a specified event | |
212 | * source. Valid sources identifiers are "udev" and "kernel". | |
213 | * | |
214 | * Applications should usually not connect directly to the | |
215 | * "kernel" events, because the devices might not be useable | |
216 | * at that time, before udev has configured them, and created | |
50579295 KS |
217 | * device nodes. Accessing devices at the same time as udev, |
218 | * might result in unpredictable behavior. The "udev" events | |
219 | * are sent out after udev has finished its event processing, | |
220 | * all rules have been processed, and needed device nodes are | |
221 | * created. | |
7459bcdc KS |
222 | * |
223 | * The initial refcount is 1, and needs to be decremented to | |
224 | * release the resources of the udev monitor. | |
225 | * | |
226 | * Returns: a new udev monitor, or #NULL, in case of an error | |
227 | **/ | |
54cf0b7f | 228 | _public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name) |
7459bcdc | 229 | { |
912541b0 | 230 | return udev_monitor_new_from_netlink_fd(udev, name, -1); |
7459bcdc KS |
231 | } |
232 | ||
e14bdd88 | 233 | static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i, |
912541b0 | 234 | unsigned short code, unsigned int data) |
e14bdd88 | 235 | { |
912541b0 | 236 | struct sock_filter *ins = &inss[*i]; |
e14bdd88 | 237 | |
912541b0 KS |
238 | ins->code = code; |
239 | ins->k = data; | |
240 | (*i)++; | |
e14bdd88 KS |
241 | } |
242 | ||
243 | static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i, | |
912541b0 KS |
244 | unsigned short code, unsigned int data, |
245 | unsigned short jt, unsigned short jf) | |
e14bdd88 | 246 | { |
912541b0 | 247 | struct sock_filter *ins = &inss[*i]; |
e14bdd88 | 248 | |
912541b0 KS |
249 | ins->code = code; |
250 | ins->jt = jt; | |
251 | ins->jf = jf; | |
252 | ins->k = data; | |
253 | (*i)++; | |
e14bdd88 KS |
254 | } |
255 | ||
ce1d6d7f KS |
256 | /** |
257 | * udev_monitor_filter_update: | |
258 | * @udev_monitor: monitor | |
259 | * | |
50579295 KS |
260 | * Update the installed socket filter. This is only needed, |
261 | * if the filter was removed or changed. | |
ce1d6d7f KS |
262 | * |
263 | * Returns: 0 on success, otherwise a negative error value. | |
264 | */ | |
54cf0b7f | 265 | _public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor) |
e14bdd88 | 266 | { |
912541b0 KS |
267 | struct sock_filter ins[512]; |
268 | struct sock_fprog filter; | |
269 | unsigned int i; | |
270 | struct udev_list_entry *list_entry; | |
271 | int err; | |
272 | ||
273 | if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL && | |
274 | udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL) | |
275 | return 0; | |
276 | ||
29804cc1 | 277 | memzero(ins, sizeof(ins)); |
912541b0 KS |
278 | i = 0; |
279 | ||
280 | /* load magic in A */ | |
281 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic)); | |
282 | /* jump if magic matches */ | |
283 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0); | |
284 | /* wrong magic, pass packet */ | |
285 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); | |
286 | ||
287 | if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) { | |
288 | int tag_matches; | |
289 | ||
290 | /* count tag matches, to calculate end of tag match block */ | |
291 | tag_matches = 0; | |
292 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) | |
293 | tag_matches++; | |
294 | ||
295 | /* add all tags matches */ | |
296 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) { | |
297 | uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry)); | |
298 | uint32_t tag_bloom_hi = tag_bloom_bits >> 32; | |
299 | uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff; | |
300 | ||
301 | /* load device bloom bits in A */ | |
302 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi)); | |
303 | /* clear bits (tag bits & bloom bits) */ | |
304 | bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi); | |
305 | /* jump to next tag if it does not match */ | |
306 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3); | |
307 | ||
308 | /* load device bloom bits in A */ | |
309 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo)); | |
310 | /* clear bits (tag bits & bloom bits) */ | |
311 | bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo); | |
312 | /* jump behind end of tag match block if tag matches */ | |
313 | tag_matches--; | |
314 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0); | |
315 | } | |
316 | ||
317 | /* nothing matched, drop packet */ | |
318 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0); | |
319 | } | |
320 | ||
321 | /* add all subsystem matches */ | |
322 | if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) { | |
323 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) { | |
324 | unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry)); | |
325 | ||
326 | /* load device subsystem value in A */ | |
327 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash)); | |
328 | if (udev_list_entry_get_value(list_entry) == NULL) { | |
329 | /* jump if subsystem does not match */ | |
330 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1); | |
331 | } else { | |
332 | /* jump if subsystem does not match */ | |
333 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3); | |
334 | ||
335 | /* load device devtype value in A */ | |
336 | bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash)); | |
337 | /* jump if value does not match */ | |
338 | hash = util_string_hash32(udev_list_entry_get_value(list_entry)); | |
339 | bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1); | |
340 | } | |
341 | ||
342 | /* matched, pass packet */ | |
343 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); | |
344 | ||
8fef0ff2 | 345 | if (i+1 >= ELEMENTSOF(ins)) |
994e0234 | 346 | return -E2BIG; |
912541b0 KS |
347 | } |
348 | ||
349 | /* nothing matched, drop packet */ | |
350 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0); | |
351 | } | |
352 | ||
353 | /* matched, pass packet */ | |
354 | bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); | |
355 | ||
356 | /* install filter */ | |
29804cc1 | 357 | memzero(&filter, sizeof(filter)); |
912541b0 KS |
358 | filter.len = i; |
359 | filter.filter = ins; | |
360 | err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); | |
994e0234 | 361 | return err < 0 ? -errno : 0; |
e14bdd88 KS |
362 | } |
363 | ||
1e03b754 KS |
364 | int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender) |
365 | { | |
b49d9b50 | 366 | udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid; |
912541b0 | 367 | return 0; |
1e03b754 | 368 | } |
ce1d6d7f KS |
369 | /** |
370 | * udev_monitor_enable_receiving: | |
371 | * @udev_monitor: the monitor which should receive events | |
372 | * | |
373 | * Binds the @udev_monitor socket to the event source. | |
374 | * | |
375 | * Returns: 0 on success, otherwise a negative error value. | |
376 | */ | |
54cf0b7f | 377 | _public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor) |
d59f11e1 | 378 | { |
912541b0 KS |
379 | int err = 0; |
380 | const int on = 1; | |
381 | ||
2d13da88 KS |
382 | udev_monitor_filter_update(udev_monitor); |
383 | ||
384 | if (!udev_monitor->bound) { | |
385 | err = bind(udev_monitor->sock, | |
b49d9b50 | 386 | &udev_monitor->snl.sa, sizeof(struct sockaddr_nl)); |
2d13da88 KS |
387 | if (err == 0) |
388 | udev_monitor->bound = true; | |
912541b0 KS |
389 | } |
390 | ||
2d13da88 | 391 | if (err >= 0) { |
b49d9b50 | 392 | union sockaddr_union snl; |
2d13da88 KS |
393 | socklen_t addrlen; |
394 | ||
395 | /* | |
396 | * get the address the kernel has assigned us | |
397 | * it is usually, but not necessarily the pid | |
398 | */ | |
399 | addrlen = sizeof(struct sockaddr_nl); | |
b49d9b50 | 400 | err = getsockname(udev_monitor->sock, &snl.sa, &addrlen); |
2d13da88 | 401 | if (err == 0) |
b49d9b50 | 402 | udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid; |
2d13da88 | 403 | } else { |
56f64d95 | 404 | log_debug_errno(errno, "bind failed: %m"); |
994e0234 | 405 | return -errno; |
912541b0 KS |
406 | } |
407 | ||
408 | /* enable receiving of sender credentials */ | |
9dedfe7f TG |
409 | err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)); |
410 | if (err < 0) | |
56f64d95 | 411 | log_debug_errno(errno, "setting SO_PASSCRED failed: %m"); |
9dedfe7f | 412 | |
912541b0 | 413 | return 0; |
ba6929f6 KS |
414 | } |
415 | ||
f712894d KS |
416 | /** |
417 | * udev_monitor_set_receive_buffer_size: | |
418 | * @udev_monitor: the monitor which should receive events | |
419 | * @size: the size in bytes | |
420 | * | |
421 | * Set the size of the kernel socket buffer. This call needs the | |
422 | * appropriate privileges to succeed. | |
423 | * | |
424 | * Returns: 0 on success, otherwise -1 on error. | |
425 | */ | |
54cf0b7f | 426 | _public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size) |
cb25a958 | 427 | { |
912541b0 | 428 | if (udev_monitor == NULL) |
994e0234 | 429 | return -EINVAL; |
912541b0 | 430 | return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size)); |
cb25a958 KS |
431 | } |
432 | ||
1e03b754 KS |
433 | int udev_monitor_disconnect(struct udev_monitor *udev_monitor) |
434 | { | |
912541b0 | 435 | int err; |
1e03b754 | 436 | |
912541b0 KS |
437 | err = close(udev_monitor->sock); |
438 | udev_monitor->sock = -1; | |
994e0234 | 439 | return err < 0 ? -errno : 0; |
1e03b754 KS |
440 | } |
441 | ||
7d8787b3 KS |
442 | /** |
443 | * udev_monitor_ref: | |
444 | * @udev_monitor: udev monitor | |
445 | * | |
446 | * Take a reference of a udev monitor. | |
447 | * | |
448 | * Returns: the passed udev monitor | |
449 | **/ | |
54cf0b7f | 450 | _public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor) |
ba6929f6 | 451 | { |
912541b0 KS |
452 | if (udev_monitor == NULL) |
453 | return NULL; | |
454 | udev_monitor->refcount++; | |
455 | return udev_monitor; | |
ba6929f6 KS |
456 | } |
457 | ||
7d8787b3 KS |
458 | /** |
459 | * udev_monitor_unref: | |
460 | * @udev_monitor: udev monitor | |
461 | * | |
ff109b8d | 462 | * Drop a reference of a udev monitor. If the refcount reaches zero, |
be7de409 | 463 | * the bound socket will be closed, and the resources of the monitor |
7d8787b3 KS |
464 | * will be released. |
465 | * | |
725d7e6c | 466 | * Returns: #NULL |
7d8787b3 | 467 | **/ |
20bbd54f | 468 | _public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor) |
ba6929f6 | 469 | { |
912541b0 | 470 | if (udev_monitor == NULL) |
20bbd54f | 471 | return NULL; |
912541b0 KS |
472 | udev_monitor->refcount--; |
473 | if (udev_monitor->refcount > 0) | |
725d7e6c | 474 | return NULL; |
912541b0 KS |
475 | if (udev_monitor->sock >= 0) |
476 | close(udev_monitor->sock); | |
477 | udev_list_cleanup(&udev_monitor->filter_subsystem_list); | |
478 | udev_list_cleanup(&udev_monitor->filter_tag_list); | |
912541b0 | 479 | free(udev_monitor); |
20bbd54f | 480 | return NULL; |
ba6929f6 KS |
481 | } |
482 | ||
7d8787b3 KS |
483 | /** |
484 | * udev_monitor_get_udev: | |
485 | * @udev_monitor: udev monitor | |
486 | * | |
b98fd840 | 487 | * Retrieve the udev library context the monitor was created with. |
7d8787b3 KS |
488 | * |
489 | * Returns: the udev library context | |
490 | **/ | |
54cf0b7f | 491 | _public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor) |
ba6929f6 | 492 | { |
912541b0 KS |
493 | if (udev_monitor == NULL) |
494 | return NULL; | |
495 | return udev_monitor->udev; | |
ba6929f6 KS |
496 | } |
497 | ||
7d8787b3 KS |
498 | /** |
499 | * udev_monitor_get_fd: | |
500 | * @udev_monitor: udev monitor | |
501 | * | |
502 | * Retrieve the socket file descriptor associated with the monitor. | |
503 | * | |
504 | * Returns: the socket file descriptor | |
505 | **/ | |
54cf0b7f | 506 | _public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor) |
ba6929f6 | 507 | { |
912541b0 | 508 | if (udev_monitor == NULL) |
994e0234 | 509 | return -EINVAL; |
912541b0 | 510 | return udev_monitor->sock; |
ba6929f6 KS |
511 | } |
512 | ||
e14bdd88 KS |
513 | static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device) |
514 | { | |
912541b0 KS |
515 | struct udev_list_entry *list_entry; |
516 | ||
517 | if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL) | |
518 | goto tag; | |
519 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) { | |
520 | const char *subsys = udev_list_entry_get_name(list_entry); | |
521 | const char *dsubsys = udev_device_get_subsystem(udev_device); | |
522 | const char *devtype; | |
523 | const char *ddevtype; | |
524 | ||
090be865 | 525 | if (!streq(dsubsys, subsys)) |
912541b0 KS |
526 | continue; |
527 | ||
528 | devtype = udev_list_entry_get_value(list_entry); | |
529 | if (devtype == NULL) | |
530 | goto tag; | |
531 | ddevtype = udev_device_get_devtype(udev_device); | |
532 | if (ddevtype == NULL) | |
533 | continue; | |
090be865 | 534 | if (streq(ddevtype, devtype)) |
912541b0 KS |
535 | goto tag; |
536 | } | |
537 | return 0; | |
28460195 KS |
538 | |
539 | tag: | |
912541b0 KS |
540 | if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL) |
541 | return 1; | |
542 | udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) { | |
543 | const char *tag = udev_list_entry_get_name(list_entry); | |
544 | ||
545 | if (udev_device_has_tag(udev_device, tag)) | |
546 | return 1; | |
547 | } | |
548 | return 0; | |
e14bdd88 KS |
549 | } |
550 | ||
7d8787b3 | 551 | /** |
d59f11e1 | 552 | * udev_monitor_receive_device: |
7d8787b3 KS |
553 | * @udev_monitor: udev monitor |
554 | * | |
d59f11e1 | 555 | * Receive data from the udev monitor socket, allocate a new udev |
b98fd840 | 556 | * device, fill in the received data, and return the device. |
7d8787b3 | 557 | * |
50579295 | 558 | * Only socket connections with uid=0 are accepted. |
7d8787b3 | 559 | * |
b30b4260 KS |
560 | * The monitor socket is by default set to NONBLOCK. A variant of poll() on |
561 | * the file descriptor returned by udev_monitor_get_fd() should to be used to | |
562 | * wake up when new devices arrive, or alternatively the file descriptor | |
563 | * switched into blocking mode. | |
564 | * | |
7d8787b3 | 565 | * The initial refcount is 1, and needs to be decremented to |
be7de409 | 566 | * release the resources of the udev device. |
7d8787b3 KS |
567 | * |
568 | * Returns: a new udev device, or #NULL, in case of an error | |
569 | **/ | |
54cf0b7f | 570 | _public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor) |
ba6929f6 | 571 | { |
912541b0 KS |
572 | struct udev_device *udev_device; |
573 | struct msghdr smsg; | |
574 | struct iovec iov; | |
575 | char cred_msg[CMSG_SPACE(sizeof(struct ucred))]; | |
576 | struct cmsghdr *cmsg; | |
b49d9b50 | 577 | union sockaddr_union snl; |
912541b0 | 578 | struct ucred *cred; |
bf3dd6b1 SL |
579 | union { |
580 | struct udev_monitor_netlink_header nlh; | |
581 | char raw[8192]; | |
582 | } buf; | |
912541b0 KS |
583 | ssize_t buflen; |
584 | ssize_t bufpos; | |
2df959ec | 585 | bool is_initialized = false; |
ba6929f6 | 586 | |
e14bdd88 | 587 | retry: |
912541b0 KS |
588 | if (udev_monitor == NULL) |
589 | return NULL; | |
912541b0 KS |
590 | iov.iov_base = &buf; |
591 | iov.iov_len = sizeof(buf); | |
29804cc1 | 592 | memzero(&smsg, sizeof(struct msghdr)); |
912541b0 KS |
593 | smsg.msg_iov = &iov; |
594 | smsg.msg_iovlen = 1; | |
595 | smsg.msg_control = cred_msg; | |
596 | smsg.msg_controllen = sizeof(cred_msg); | |
f6613dd9 KS |
597 | smsg.msg_name = &snl; |
598 | smsg.msg_namelen = sizeof(snl); | |
912541b0 | 599 | |
a38d9945 | 600 | buflen = recvmsg(udev_monitor->sock, &smsg, 0); |
912541b0 KS |
601 | if (buflen < 0) { |
602 | if (errno != EINTR) | |
ff49bc32 | 603 | log_debug("unable to receive message"); |
912541b0 KS |
604 | return NULL; |
605 | } | |
606 | ||
9c89c1ca | 607 | if (buflen < 32 || (smsg.msg_flags & MSG_TRUNC)) { |
ff49bc32 | 608 | log_debug("invalid message length"); |
912541b0 KS |
609 | return NULL; |
610 | } | |
611 | ||
f6613dd9 KS |
612 | if (snl.nl.nl_groups == 0) { |
613 | /* unicast message, check if we trust the sender */ | |
614 | if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 || | |
615 | snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) { | |
ff49bc32 | 616 | log_debug("unicast netlink message ignored"); |
f6613dd9 KS |
617 | return NULL; |
618 | } | |
619 | } else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) { | |
620 | if (snl.nl.nl_pid > 0) { | |
1fa2f38f ZJS |
621 | log_debug("multicast kernel netlink message from PID %"PRIu32" ignored", |
622 | snl.nl.nl_pid); | |
f6613dd9 | 623 | return NULL; |
912541b0 KS |
624 | } |
625 | } | |
626 | ||
627 | cmsg = CMSG_FIRSTHDR(&smsg); | |
628 | if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) { | |
ff49bc32 | 629 | log_debug("no sender credentials received, message ignored"); |
912541b0 KS |
630 | return NULL; |
631 | } | |
632 | ||
633 | cred = (struct ucred *)CMSG_DATA(cmsg); | |
634 | if (cred->uid != 0) { | |
1fa2f38f | 635 | log_debug("sender uid="UID_FMT", message ignored", cred->uid); |
912541b0 KS |
636 | return NULL; |
637 | } | |
638 | ||
bf3dd6b1 | 639 | if (memcmp(buf.raw, "libudev", 8) == 0) { |
912541b0 | 640 | /* udev message needs proper version magic */ |
bf3dd6b1 | 641 | if (buf.nlh.magic != htonl(UDEV_MONITOR_MAGIC)) { |
ff49bc32 | 642 | log_debug("unrecognized message signature (%x != %x)", |
bf3dd6b1 | 643 | buf.nlh.magic, htonl(UDEV_MONITOR_MAGIC)); |
912541b0 KS |
644 | return NULL; |
645 | } | |
bf3dd6b1 | 646 | if (buf.nlh.properties_off+32 > (size_t)buflen) { |
e6ac88dd TG |
647 | log_debug("message smaller than expected (%u > %zd)", |
648 | buf.nlh.properties_off+32, buflen); | |
912541b0 | 649 | return NULL; |
f6613dd9 KS |
650 | } |
651 | ||
bf3dd6b1 | 652 | bufpos = buf.nlh.properties_off; |
f6613dd9 KS |
653 | |
654 | /* devices received from udev are always initialized */ | |
2df959ec | 655 | is_initialized = true; |
912541b0 KS |
656 | } else { |
657 | /* kernel message with header */ | |
bf3dd6b1 | 658 | bufpos = strlen(buf.raw) + 1; |
912541b0 | 659 | if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) { |
ff49bc32 | 660 | log_debug("invalid message length"); |
912541b0 KS |
661 | return NULL; |
662 | } | |
663 | ||
664 | /* check message header */ | |
bf3dd6b1 | 665 | if (strstr(buf.raw, "@/") == NULL) { |
ff49bc32 | 666 | log_debug("unrecognized message header"); |
912541b0 KS |
667 | return NULL; |
668 | } | |
669 | } | |
670 | ||
2df959ec | 671 | udev_device = udev_device_new_from_nulstr(udev_monitor->udev, &buf.raw[bufpos], buflen - bufpos); |
e6ac88dd TG |
672 | if (!udev_device) { |
673 | log_debug("could not create device: %m"); | |
912541b0 | 674 | return NULL; |
e6ac88dd | 675 | } |
2df959ec TG |
676 | |
677 | if (is_initialized) | |
678 | udev_device_set_is_initialized(udev_device); | |
912541b0 KS |
679 | |
680 | /* skip device, if it does not pass the current filter */ | |
681 | if (!passes_filter(udev_monitor, udev_device)) { | |
682 | struct pollfd pfd[1]; | |
683 | int rc; | |
684 | ||
685 | udev_device_unref(udev_device); | |
686 | ||
687 | /* if something is queued, get next device */ | |
688 | pfd[0].fd = udev_monitor->sock; | |
689 | pfd[0].events = POLLIN; | |
690 | rc = poll(pfd, 1, 0); | |
691 | if (rc > 0) | |
692 | goto retry; | |
693 | return NULL; | |
694 | } | |
695 | ||
696 | return udev_device; | |
ba6929f6 | 697 | } |
9925ab04 | 698 | |
1e03b754 | 699 | int udev_monitor_send_device(struct udev_monitor *udev_monitor, |
912541b0 | 700 | struct udev_monitor *destination, struct udev_device *udev_device) |
9925ab04 | 701 | { |
81b9fe54 ZJS |
702 | const char *buf, *val; |
703 | ssize_t blen, count; | |
704 | struct udev_monitor_netlink_header nlh = { | |
705 | .prefix = "libudev", | |
706 | .magic = htonl(UDEV_MONITOR_MAGIC), | |
707 | .header_size = sizeof nlh, | |
708 | }; | |
709 | struct iovec iov[2] = { | |
710 | { .iov_base = &nlh, .iov_len = sizeof nlh }, | |
711 | }; | |
712 | struct msghdr smsg = { | |
713 | .msg_iov = iov, | |
714 | .msg_iovlen = 2, | |
715 | }; | |
2d13da88 KS |
716 | struct udev_list_entry *list_entry; |
717 | uint64_t tag_bloom_bits; | |
718 | ||
912541b0 | 719 | blen = udev_device_get_properties_monitor_buf(udev_device, &buf); |
e6ac88dd TG |
720 | if (blen < 32) { |
721 | log_debug("device buffer is too small to contain a valid device"); | |
912541b0 | 722 | return -EINVAL; |
e6ac88dd | 723 | } |
912541b0 | 724 | |
81b9fe54 | 725 | /* fill in versioned header */ |
2d13da88 KS |
726 | val = udev_device_get_subsystem(udev_device); |
727 | nlh.filter_subsystem_hash = htonl(util_string_hash32(val)); | |
81b9fe54 | 728 | |
2d13da88 KS |
729 | val = udev_device_get_devtype(udev_device); |
730 | if (val != NULL) | |
731 | nlh.filter_devtype_hash = htonl(util_string_hash32(val)); | |
2d13da88 KS |
732 | |
733 | /* add tag bloom filter */ | |
734 | tag_bloom_bits = 0; | |
735 | udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device)) | |
736 | tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry)); | |
737 | if (tag_bloom_bits > 0) { | |
738 | nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32); | |
739 | nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff); | |
912541b0 KS |
740 | } |
741 | ||
2d13da88 KS |
742 | /* add properties list */ |
743 | nlh.properties_off = iov[0].iov_len; | |
744 | nlh.properties_len = blen; | |
745 | iov[1].iov_base = (char *)buf; | |
746 | iov[1].iov_len = blen; | |
912541b0 | 747 | |
2d13da88 KS |
748 | /* |
749 | * Use custom address for target, or the default one. | |
750 | * | |
751 | * If we send to a multicast group, we will get | |
752 | * ECONNREFUSED, which is expected. | |
753 | */ | |
a4445e88 | 754 | if (destination) |
2d13da88 KS |
755 | smsg.msg_name = &destination->snl; |
756 | else | |
757 | smsg.msg_name = &udev_monitor->snl_destination; | |
758 | smsg.msg_namelen = sizeof(struct sockaddr_nl); | |
759 | count = sendmsg(udev_monitor->sock, &smsg, 0); | |
a4445e88 TG |
760 | if (count < 0) { |
761 | if (!destination && errno == ECONNREFUSED) { | |
762 | log_debug("passed unknown number of bytes to netlink monitor %p", udev_monitor); | |
763 | return 0; | |
764 | } else | |
765 | return -errno; | |
766 | } | |
767 | ||
ff49bc32 | 768 | log_debug("passed %zi bytes to netlink monitor %p", count, udev_monitor); |
2d13da88 | 769 | return count; |
9925ab04 | 770 | } |
e14bdd88 | 771 | |
ce1d6d7f KS |
772 | /** |
773 | * udev_monitor_filter_add_match_subsystem_devtype: | |
774 | * @udev_monitor: the monitor | |
775 | * @subsystem: the subsystem value to match the incoming devices against | |
214a6c79 | 776 | * @devtype: the devtype value to match the incoming devices against |
ce1d6d7f | 777 | * |
50579295 | 778 | * This filter is efficiently executed inside the kernel, and libudev subscribers |
28460195 KS |
779 | * will usually not be woken up for devices which do not match. |
780 | * | |
ce1d6d7f KS |
781 | * The filter must be installed before the monitor is switched to listening mode. |
782 | * | |
783 | * Returns: 0 on success, otherwise a negative error value. | |
784 | */ | |
54cf0b7f | 785 | _public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype) |
e14bdd88 | 786 | { |
912541b0 KS |
787 | if (udev_monitor == NULL) |
788 | return -EINVAL; | |
789 | if (subsystem == NULL) | |
790 | return -EINVAL; | |
791 | if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL) | |
792 | return -ENOMEM; | |
793 | return 0; | |
e14bdd88 | 794 | } |
08a7a795 | 795 | |
28460195 KS |
796 | /** |
797 | * udev_monitor_filter_add_match_tag: | |
798 | * @udev_monitor: the monitor | |
799 | * @tag: the name of a tag | |
800 | * | |
50579295 | 801 | * This filter is efficiently executed inside the kernel, and libudev subscribers |
28460195 KS |
802 | * will usually not be woken up for devices which do not match. |
803 | * | |
804 | * The filter must be installed before the monitor is switched to listening mode. | |
805 | * | |
806 | * Returns: 0 on success, otherwise a negative error value. | |
807 | */ | |
54cf0b7f | 808 | _public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag) |
28460195 | 809 | { |
912541b0 KS |
810 | if (udev_monitor == NULL) |
811 | return -EINVAL; | |
812 | if (tag == NULL) | |
813 | return -EINVAL; | |
814 | if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL) | |
815 | return -ENOMEM; | |
816 | return 0; | |
28460195 KS |
817 | } |
818 | ||
ce1d6d7f KS |
819 | /** |
820 | * udev_monitor_filter_remove: | |
821 | * @udev_monitor: monitor | |
822 | * | |
823 | * Remove all filters from monitor. | |
824 | * | |
825 | * Returns: 0 on success, otherwise a negative error value. | |
826 | */ | |
54cf0b7f | 827 | _public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor) |
08a7a795 | 828 | { |
912541b0 | 829 | static struct sock_fprog filter = { 0, NULL }; |
08a7a795 | 830 | |
912541b0 KS |
831 | udev_list_cleanup(&udev_monitor->filter_subsystem_list); |
832 | return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); | |
08a7a795 | 833 | } |