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