1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3 #include <fcntl.h>
4 #include <netinet/in.h>
5 #include <poll.h>
6 #include <sys/ioctl.h>
7 #include <sys/stat.h>
8 #include <sys/types.h>
9 #include <unistd.h>
10
11 #include "af-list.h"
12 #include "alloc-util.h"
13 #include "bus-polkit.h"
14 #include "dirent-util.h"
15 #include "dns-domain.h"
16 #include "event-util.h"
17 #include "fd-util.h"
18 #include "fileio.h"
19 #include "hostname-util.h"
20 #include "idn-util.h"
21 #include "io-util.h"
22 #include "missing_network.h"
23 #include "missing_socket.h"
24 #include "netlink-util.h"
25 #include "ordered-set.h"
26 #include "parse-util.h"
27 #include "random-util.h"
28 #include "resolved-bus.h"
29 #include "resolved-conf.h"
30 #include "resolved-dns-stub.h"
31 #include "resolved-dnssd.h"
32 #include "resolved-etc-hosts.h"
33 #include "resolved-llmnr.h"
34 #include "resolved-manager.h"
35 #include "resolved-mdns.h"
36 #include "resolved-resolv-conf.h"
37 #include "resolved-util.h"
38 #include "resolved-varlink.h"
39 #include "socket-util.h"
40 #include "string-table.h"
41 #include "string-util.h"
42 #include "utf8.h"
43
44 #define SEND_TIMEOUT_USEC (200 * USEC_PER_MSEC)
45
manager_process_link(sd_netlink * rtnl,sd_netlink_message * mm,void * userdata)46 static int manager_process_link(sd_netlink *rtnl, sd_netlink_message *mm, void *userdata) {
47 Manager *m = userdata;
48 uint16_t type;
49 Link *l;
50 int ifindex, r;
51
52 assert(rtnl);
53 assert(m);
54 assert(mm);
55
56 r = sd_netlink_message_get_type(mm, &type);
57 if (r < 0)
58 goto fail;
59
60 r = sd_rtnl_message_link_get_ifindex(mm, &ifindex);
61 if (r < 0)
62 goto fail;
63
64 l = hashmap_get(m->links, INT_TO_PTR(ifindex));
65
66 switch (type) {
67
68 case RTM_NEWLINK:{
69 bool is_new = !l;
70
71 if (!l) {
72 r = link_new(m, &l, ifindex);
73 if (r < 0)
74 goto fail;
75 }
76
77 r = link_process_rtnl(l, mm);
78 if (r < 0)
79 goto fail;
80
81 r = link_update(l);
82 if (r < 0)
83 goto fail;
84
85 if (is_new)
86 log_debug("Found new link %i/%s", ifindex, l->ifname);
87
88 break;
89 }
90
91 case RTM_DELLINK:
92 if (l) {
93 log_debug("Removing link %i/%s", l->ifindex, l->ifname);
94 link_remove_user(l);
95 link_free(l);
96 }
97
98 break;
99 }
100
101 return 0;
102
103 fail:
104 log_warning_errno(r, "Failed to process RTNL link message: %m");
105 return 0;
106 }
107
manager_process_address(sd_netlink * rtnl,sd_netlink_message * mm,void * userdata)108 static int manager_process_address(sd_netlink *rtnl, sd_netlink_message *mm, void *userdata) {
109 Manager *m = userdata;
110 union in_addr_union address;
111 uint16_t type;
112 int r, ifindex, family;
113 LinkAddress *a;
114 Link *l;
115
116 assert(rtnl);
117 assert(mm);
118 assert(m);
119
120 r = sd_netlink_message_get_type(mm, &type);
121 if (r < 0)
122 goto fail;
123
124 r = sd_rtnl_message_addr_get_ifindex(mm, &ifindex);
125 if (r < 0)
126 goto fail;
127
128 l = hashmap_get(m->links, INT_TO_PTR(ifindex));
129 if (!l)
130 return 0;
131
132 r = sd_rtnl_message_addr_get_family(mm, &family);
133 if (r < 0)
134 goto fail;
135
136 switch (family) {
137
138 case AF_INET:
139 r = sd_netlink_message_read_in_addr(mm, IFA_LOCAL, &address.in);
140 if (r < 0) {
141 r = sd_netlink_message_read_in_addr(mm, IFA_ADDRESS, &address.in);
142 if (r < 0)
143 goto fail;
144 }
145
146 break;
147
148 case AF_INET6:
149 r = sd_netlink_message_read_in6_addr(mm, IFA_LOCAL, &address.in6);
150 if (r < 0) {
151 r = sd_netlink_message_read_in6_addr(mm, IFA_ADDRESS, &address.in6);
152 if (r < 0)
153 goto fail;
154 }
155
156 break;
157
158 default:
159 return 0;
160 }
161
162 a = link_find_address(l, family, &address);
163
164 switch (type) {
165
166 case RTM_NEWADDR:
167
168 if (!a) {
169 r = link_address_new(l, &a, family, &address);
170 if (r < 0)
171 return r;
172 }
173
174 r = link_address_update_rtnl(a, mm);
175 if (r < 0)
176 return r;
177
178 break;
179
180 case RTM_DELADDR:
181 link_address_free(a);
182 break;
183 }
184
185 return 0;
186
187 fail:
188 log_warning_errno(r, "Failed to process RTNL address message: %m");
189 return 0;
190 }
191
manager_rtnl_listen(Manager * m)192 static int manager_rtnl_listen(Manager *m) {
193 _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL, *reply = NULL;
194 sd_netlink_message *i;
195 int r;
196
197 assert(m);
198
199 /* First, subscribe to interfaces coming and going */
200 r = sd_netlink_open(&m->rtnl);
201 if (r < 0)
202 return r;
203
204 r = sd_netlink_attach_event(m->rtnl, m->event, SD_EVENT_PRIORITY_IMPORTANT);
205 if (r < 0)
206 return r;
207
208 r = sd_netlink_add_match(m->rtnl, NULL, RTM_NEWLINK, manager_process_link, NULL, m, "resolve-NEWLINK");
209 if (r < 0)
210 return r;
211
212 r = sd_netlink_add_match(m->rtnl, NULL, RTM_DELLINK, manager_process_link, NULL, m, "resolve-DELLINK");
213 if (r < 0)
214 return r;
215
216 r = sd_netlink_add_match(m->rtnl, NULL, RTM_NEWADDR, manager_process_address, NULL, m, "resolve-NEWADDR");
217 if (r < 0)
218 return r;
219
220 r = sd_netlink_add_match(m->rtnl, NULL, RTM_DELADDR, manager_process_address, NULL, m, "resolve-DELADDR");
221 if (r < 0)
222 return r;
223
224 /* Then, enumerate all links */
225 r = sd_rtnl_message_new_link(m->rtnl, &req, RTM_GETLINK, 0);
226 if (r < 0)
227 return r;
228
229 r = sd_netlink_message_request_dump(req, true);
230 if (r < 0)
231 return r;
232
233 r = sd_netlink_call(m->rtnl, req, 0, &reply);
234 if (r < 0)
235 return r;
236
237 for (i = reply; i; i = sd_netlink_message_next(i)) {
238 r = manager_process_link(m->rtnl, i, m);
239 if (r < 0)
240 return r;
241 }
242
243 req = sd_netlink_message_unref(req);
244 reply = sd_netlink_message_unref(reply);
245
246 /* Finally, enumerate all addresses, too */
247 r = sd_rtnl_message_new_addr(m->rtnl, &req, RTM_GETADDR, 0, AF_UNSPEC);
248 if (r < 0)
249 return r;
250
251 r = sd_netlink_message_request_dump(req, true);
252 if (r < 0)
253 return r;
254
255 r = sd_netlink_call(m->rtnl, req, 0, &reply);
256 if (r < 0)
257 return r;
258
259 for (i = reply; i; i = sd_netlink_message_next(i)) {
260 r = manager_process_address(m->rtnl, i, m);
261 if (r < 0)
262 return r;
263 }
264
265 return r;
266 }
267
on_network_event(sd_event_source * s,int fd,uint32_t revents,void * userdata)268 static int on_network_event(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
269 Manager *m = userdata;
270 Link *l;
271 int r;
272
273 assert(m);
274
275 sd_network_monitor_flush(m->network_monitor);
276
277 HASHMAP_FOREACH(l, m->links) {
278 r = link_update(l);
279 if (r < 0)
280 log_warning_errno(r, "Failed to update monitor information for %i: %m", l->ifindex);
281 }
282
283 (void) manager_write_resolv_conf(m);
284 (void) manager_send_changed(m, "DNS");
285
286 return 0;
287 }
288
manager_network_monitor_listen(Manager * m)289 static int manager_network_monitor_listen(Manager *m) {
290 int r, fd, events;
291
292 assert(m);
293
294 r = sd_network_monitor_new(&m->network_monitor, NULL);
295 if (r < 0)
296 return r;
297
298 fd = sd_network_monitor_get_fd(m->network_monitor);
299 if (fd < 0)
300 return fd;
301
302 events = sd_network_monitor_get_events(m->network_monitor);
303 if (events < 0)
304 return events;
305
306 r = sd_event_add_io(m->event, &m->network_event_source, fd, events, &on_network_event, m);
307 if (r < 0)
308 return r;
309
310 r = sd_event_source_set_priority(m->network_event_source, SD_EVENT_PRIORITY_IMPORTANT+5);
311 if (r < 0)
312 return r;
313
314 (void) sd_event_source_set_description(m->network_event_source, "network-monitor");
315
316 return 0;
317 }
318
319 static int manager_clock_change_listen(Manager *m);
320
on_clock_change(sd_event_source * source,int fd,uint32_t revents,void * userdata)321 static int on_clock_change(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
322 Manager *m = userdata;
323
324 assert(m);
325
326 /* The clock has changed, let's flush all caches. Why that? That's because DNSSEC validation takes
327 * the system clock into consideration, and if the clock changes the old validations might have been
328 * wrong. Let's redo all validation with the new, correct time.
329 *
330 * (Also, this is triggered after system suspend, which is also a good reason to drop caches, since
331 * we might be connected to a different network now without this being visible in a dropped link
332 * carrier or so.) */
333
334 log_info("Clock change detected. Flushing caches.");
335 manager_flush_caches(m, LOG_DEBUG /* downgrade the functions own log message, since we already logged here at LOG_INFO level */);
336
337 /* The clock change timerfd is unusable after it triggered once, create a new one. */
338 return manager_clock_change_listen(m);
339 }
340
manager_clock_change_listen(Manager * m)341 static int manager_clock_change_listen(Manager *m) {
342 int r;
343
344 assert(m);
345
346 m->clock_change_event_source = sd_event_source_disable_unref(m->clock_change_event_source);
347
348 r = event_add_time_change(m->event, &m->clock_change_event_source, on_clock_change, m);
349 if (r < 0)
350 return log_error_errno(r, "Failed to create clock change event source: %m");
351
352 return 0;
353 }
354
determine_hostnames(char ** full_hostname,char ** llmnr_hostname,char ** mdns_hostname)355 static int determine_hostnames(char **full_hostname, char **llmnr_hostname, char **mdns_hostname) {
356 _cleanup_free_ char *h = NULL, *n = NULL;
357 int r;
358
359 assert(full_hostname);
360 assert(llmnr_hostname);
361 assert(mdns_hostname);
362
363 r = resolve_system_hostname(&h, &n);
364 if (r < 0)
365 return r;
366
367 r = dns_name_concat(n, "local", 0, mdns_hostname);
368 if (r < 0)
369 return log_error_errno(r, "Failed to determine mDNS hostname: %m");
370
371 *llmnr_hostname = TAKE_PTR(n);
372 *full_hostname = TAKE_PTR(h);
373
374 return 0;
375 }
376
fallback_hostname(void)377 static char* fallback_hostname(void) {
378
379 /* Determine the fall back hostname. For exposing this system to the outside world, we cannot have it
380 * to be "localhost" even if that's the default hostname. In this case, let's revert to "linux"
381 * instead. */
382
383 _cleanup_free_ char *n = get_default_hostname();
384 if (!n)
385 return NULL;
386
387 if (is_localhost(n))
388 return strdup("linux");
389
390 return TAKE_PTR(n);
391 }
392
make_fallback_hostnames(char ** full_hostname,char ** llmnr_hostname,char ** mdns_hostname)393 static int make_fallback_hostnames(char **full_hostname, char **llmnr_hostname, char **mdns_hostname) {
394 _cleanup_free_ char *h = NULL, *n = NULL, *m = NULL;
395 char label[DNS_LABEL_MAX];
396 const char *p;
397 int r;
398
399 assert(full_hostname);
400 assert(llmnr_hostname);
401 assert(mdns_hostname);
402
403 p = h = fallback_hostname();
404 if (!h)
405 return log_oom();
406
407 r = dns_label_unescape(&p, label, sizeof label, 0);
408 if (r < 0)
409 return log_error_errno(r, "Failed to unescape fallback hostname: %m");
410
411 assert(r > 0); /* The fallback hostname must have at least one label */
412
413 r = dns_label_escape_new(label, r, &n);
414 if (r < 0)
415 return log_error_errno(r, "Failed to escape fallback hostname: %m");
416
417 r = dns_name_concat(n, "local", 0, &m);
418 if (r < 0)
419 return log_error_errno(r, "Failed to concatenate mDNS hostname: %m");
420
421 *llmnr_hostname = TAKE_PTR(n);
422 *mdns_hostname = TAKE_PTR(m);
423 *full_hostname = TAKE_PTR(h);
424
425 return 0;
426 }
427
on_hostname_change(sd_event_source * es,int fd,uint32_t revents,void * userdata)428 static int on_hostname_change(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
429 _cleanup_free_ char *full_hostname = NULL, *llmnr_hostname = NULL, *mdns_hostname = NULL;
430 Manager *m = userdata;
431 bool llmnr_hostname_changed;
432 int r;
433
434 assert(m);
435
436 r = determine_hostnames(&full_hostname, &llmnr_hostname, &mdns_hostname);
437 if (r < 0) {
438 log_warning_errno(r, "Failed to determine the local hostname and LLMNR/mDNS names, ignoring: %m");
439 return 0; /* ignore invalid hostnames */
440 }
441
442 llmnr_hostname_changed = !streq(llmnr_hostname, m->llmnr_hostname);
443 if (streq(full_hostname, m->full_hostname) &&
444 !llmnr_hostname_changed &&
445 streq(mdns_hostname, m->mdns_hostname))
446 return 0;
447
448 log_info("System hostname changed to '%s'.", full_hostname);
449
450 free_and_replace(m->full_hostname, full_hostname);
451 free_and_replace(m->llmnr_hostname, llmnr_hostname);
452 free_and_replace(m->mdns_hostname, mdns_hostname);
453
454 manager_refresh_rrs(m);
455 (void) manager_send_changed(m, "LLMNRHostname");
456
457 return 0;
458 }
459
manager_watch_hostname(Manager * m)460 static int manager_watch_hostname(Manager *m) {
461 int r;
462
463 assert(m);
464
465 m->hostname_fd = open("/proc/sys/kernel/hostname",
466 O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
467 if (m->hostname_fd < 0) {
468 log_warning_errno(errno, "Failed to watch hostname: %m");
469 return 0;
470 }
471
472 r = sd_event_add_io(m->event, &m->hostname_event_source, m->hostname_fd, 0, on_hostname_change, m);
473 if (r < 0) {
474 if (r == -EPERM)
475 /* kernels prior to 3.2 don't support polling this file. Ignore the failure. */
476 m->hostname_fd = safe_close(m->hostname_fd);
477 else
478 return log_error_errno(r, "Failed to add hostname event source: %m");
479 }
480
481 (void) sd_event_source_set_description(m->hostname_event_source, "hostname");
482
483 r = determine_hostnames(&m->full_hostname, &m->llmnr_hostname, &m->mdns_hostname);
484 if (r < 0) {
485 _cleanup_free_ char *d = NULL;
486
487 d = fallback_hostname();
488 if (!d)
489 return log_oom();
490
491 log_info("Defaulting to hostname '%s'.", d);
492
493 r = make_fallback_hostnames(&m->full_hostname, &m->llmnr_hostname, &m->mdns_hostname);
494 if (r < 0)
495 return r;
496 } else
497 log_info("Using system hostname '%s'.", m->full_hostname);
498
499 return 0;
500 }
501
manager_sigusr1(sd_event_source * s,const struct signalfd_siginfo * si,void * userdata)502 static int manager_sigusr1(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
503 _cleanup_free_ char *buffer = NULL;
504 _cleanup_fclose_ FILE *f = NULL;
505 Manager *m = userdata;
506 size_t size = 0;
507 Link *l;
508
509 assert(s);
510 assert(si);
511 assert(m);
512
513 f = open_memstream_unlocked(&buffer, &size);
514 if (!f)
515 return log_oom();
516
517 LIST_FOREACH(scopes, scope, m->dns_scopes)
518 dns_scope_dump(scope, f);
519
520 LIST_FOREACH(servers, server, m->dns_servers)
521 dns_server_dump(server, f);
522 LIST_FOREACH(servers, server, m->fallback_dns_servers)
523 dns_server_dump(server, f);
524 HASHMAP_FOREACH(l, m->links)
525 LIST_FOREACH(servers, server, l->dns_servers)
526 dns_server_dump(server, f);
527
528 if (fflush_and_check(f) < 0)
529 return log_oom();
530
531 log_dump(LOG_INFO, buffer);
532 return 0;
533 }
534
manager_sigusr2(sd_event_source * s,const struct signalfd_siginfo * si,void * userdata)535 static int manager_sigusr2(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
536 Manager *m = userdata;
537
538 assert(s);
539 assert(si);
540 assert(m);
541
542 manager_flush_caches(m, LOG_INFO);
543
544 return 0;
545 }
546
manager_sigrtmin1(sd_event_source * s,const struct signalfd_siginfo * si,void * userdata)547 static int manager_sigrtmin1(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
548 Manager *m = userdata;
549
550 assert(s);
551 assert(si);
552 assert(m);
553
554 manager_reset_server_features(m);
555 return 0;
556 }
557
manager_new(Manager ** ret)558 int manager_new(Manager **ret) {
559 _cleanup_(manager_freep) Manager *m = NULL;
560 int r;
561
562 assert(ret);
563
564 m = new(Manager, 1);
565 if (!m)
566 return -ENOMEM;
567
568 *m = (Manager) {
569 .llmnr_ipv4_udp_fd = -1,
570 .llmnr_ipv6_udp_fd = -1,
571 .llmnr_ipv4_tcp_fd = -1,
572 .llmnr_ipv6_tcp_fd = -1,
573 .mdns_ipv4_fd = -1,
574 .mdns_ipv6_fd = -1,
575 .hostname_fd = -1,
576
577 .llmnr_support = DEFAULT_LLMNR_MODE,
578 .mdns_support = DEFAULT_MDNS_MODE,
579 .dnssec_mode = DEFAULT_DNSSEC_MODE,
580 .dns_over_tls_mode = DEFAULT_DNS_OVER_TLS_MODE,
581 .enable_cache = DNS_CACHE_MODE_YES,
582 .dns_stub_listener_mode = DNS_STUB_LISTENER_YES,
583 .read_resolv_conf = true,
584 .need_builtin_fallbacks = true,
585 .etc_hosts_last = USEC_INFINITY,
586 .read_etc_hosts = true,
587 };
588
589 r = dns_trust_anchor_load(&m->trust_anchor);
590 if (r < 0)
591 return r;
592
593 r = manager_parse_config_file(m);
594 if (r < 0)
595 log_warning_errno(r, "Failed to parse configuration file: %m");
596
597 #if ENABLE_DNS_OVER_TLS
598 r = dnstls_manager_init(m);
599 if (r < 0)
600 return r;
601 #endif
602
603 r = sd_event_default(&m->event);
604 if (r < 0)
605 return r;
606
607 (void) sd_event_add_signal(m->event, NULL, SIGTERM, NULL, NULL);
608 (void) sd_event_add_signal(m->event, NULL, SIGINT, NULL, NULL);
609
610 (void) sd_event_set_watchdog(m->event, true);
611
612 r = manager_watch_hostname(m);
613 if (r < 0)
614 return r;
615
616 r = dnssd_load(m);
617 if (r < 0)
618 log_warning_errno(r, "Failed to load DNS-SD configuration files: %m");
619
620 r = dns_scope_new(m, &m->unicast_scope, NULL, DNS_PROTOCOL_DNS, AF_UNSPEC);
621 if (r < 0)
622 return r;
623
624 r = manager_network_monitor_listen(m);
625 if (r < 0)
626 return r;
627
628 r = manager_rtnl_listen(m);
629 if (r < 0)
630 return r;
631
632 r = manager_clock_change_listen(m);
633 if (r < 0)
634 return r;
635
636 r = manager_connect_bus(m);
637 if (r < 0)
638 return r;
639
640 (void) sd_event_add_signal(m->event, &m->sigusr1_event_source, SIGUSR1, manager_sigusr1, m);
641 (void) sd_event_add_signal(m->event, &m->sigusr2_event_source, SIGUSR2, manager_sigusr2, m);
642 (void) sd_event_add_signal(m->event, &m->sigrtmin1_event_source, SIGRTMIN+1, manager_sigrtmin1, m);
643
644 manager_cleanup_saved_user(m);
645
646 *ret = TAKE_PTR(m);
647
648 return 0;
649 }
650
manager_start(Manager * m)651 int manager_start(Manager *m) {
652 int r;
653
654 assert(m);
655
656 r = manager_dns_stub_start(m);
657 if (r < 0)
658 return r;
659
660 r = manager_varlink_init(m);
661 if (r < 0)
662 return r;
663
664 return 0;
665 }
666
manager_free(Manager * m)667 Manager *manager_free(Manager *m) {
668 Link *l;
669 DnssdService *s;
670
671 if (!m)
672 return NULL;
673
674 dns_server_unlink_all(m->dns_servers);
675 dns_server_unlink_all(m->fallback_dns_servers);
676 dns_search_domain_unlink_all(m->search_domains);
677
678 while ((l = hashmap_first(m->links)))
679 link_free(l);
680
681 while (m->dns_queries)
682 dns_query_free(m->dns_queries);
683
684 m->stub_queries_by_packet = hashmap_free(m->stub_queries_by_packet);
685
686 dns_scope_free(m->unicast_scope);
687
688 /* At this point only orphaned streams should remain. All others should have been freed already by their
689 * owners */
690 while (m->dns_streams)
691 dns_stream_unref(m->dns_streams);
692
693 #if ENABLE_DNS_OVER_TLS
694 dnstls_manager_free(m);
695 #endif
696
697 hashmap_free(m->links);
698 hashmap_free(m->dns_transactions);
699
700 sd_event_source_unref(m->network_event_source);
701 sd_network_monitor_unref(m->network_monitor);
702
703 sd_netlink_unref(m->rtnl);
704 sd_event_source_unref(m->rtnl_event_source);
705 sd_event_source_unref(m->clock_change_event_source);
706
707 manager_llmnr_stop(m);
708 manager_mdns_stop(m);
709 manager_dns_stub_stop(m);
710 manager_varlink_done(m);
711
712 manager_socket_graveyard_clear(m);
713
714 ordered_set_free(m->dns_extra_stub_listeners);
715
716 bus_verify_polkit_async_registry_free(m->polkit_registry);
717
718 sd_bus_flush_close_unref(m->bus);
719
720 sd_event_source_unref(m->sigusr1_event_source);
721 sd_event_source_unref(m->sigusr2_event_source);
722 sd_event_source_unref(m->sigrtmin1_event_source);
723
724 dns_resource_key_unref(m->llmnr_host_ipv4_key);
725 dns_resource_key_unref(m->llmnr_host_ipv6_key);
726 dns_resource_key_unref(m->mdns_host_ipv4_key);
727 dns_resource_key_unref(m->mdns_host_ipv6_key);
728
729 sd_event_source_unref(m->hostname_event_source);
730 safe_close(m->hostname_fd);
731
732 sd_event_unref(m->event);
733
734 free(m->full_hostname);
735 free(m->llmnr_hostname);
736 free(m->mdns_hostname);
737
738 while ((s = hashmap_first(m->dnssd_services)))
739 dnssd_service_free(s);
740 hashmap_free(m->dnssd_services);
741
742 dns_trust_anchor_flush(&m->trust_anchor);
743 manager_etc_hosts_flush(m);
744
745 return mfree(m);
746 }
747
manager_recv(Manager * m,int fd,DnsProtocol protocol,DnsPacket ** ret)748 int manager_recv(Manager *m, int fd, DnsProtocol protocol, DnsPacket **ret) {
749 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
750 CMSG_BUFFER_TYPE(CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))
751 + CMSG_SPACE(int) /* ttl/hoplimit */
752 + EXTRA_CMSG_SPACE /* kernel appears to require extra buffer space */) control;
753 union sockaddr_union sa;
754 struct iovec iov;
755 struct msghdr mh = {
756 .msg_name = &sa.sa,
757 .msg_namelen = sizeof(sa),
758 .msg_iov = &iov,
759 .msg_iovlen = 1,
760 .msg_control = &control,
761 .msg_controllen = sizeof(control),
762 };
763 struct cmsghdr *cmsg;
764 ssize_t ms, l;
765 int r;
766
767 assert(m);
768 assert(fd >= 0);
769 assert(ret);
770
771 ms = next_datagram_size_fd(fd);
772 if (ms < 0)
773 return ms;
774
775 r = dns_packet_new(&p, protocol, ms, DNS_PACKET_SIZE_MAX);
776 if (r < 0)
777 return r;
778
779 iov = IOVEC_MAKE(DNS_PACKET_DATA(p), p->allocated);
780
781 l = recvmsg_safe(fd, &mh, 0);
782 if (l < 0) {
783 if (ERRNO_IS_TRANSIENT(l))
784 return 0;
785 return l;
786 }
787 if (l == 0)
788 return 0;
789
790 assert(!(mh.msg_flags & MSG_TRUNC));
791
792 p->size = (size_t) l;
793
794 p->family = sa.sa.sa_family;
795 p->ipproto = IPPROTO_UDP;
796 if (p->family == AF_INET) {
797 p->sender.in = sa.in.sin_addr;
798 p->sender_port = be16toh(sa.in.sin_port);
799 } else if (p->family == AF_INET6) {
800 p->sender.in6 = sa.in6.sin6_addr;
801 p->sender_port = be16toh(sa.in6.sin6_port);
802 p->ifindex = sa.in6.sin6_scope_id;
803 } else
804 return -EAFNOSUPPORT;
805
806 p->timestamp = now(CLOCK_BOOTTIME);
807
808 CMSG_FOREACH(cmsg, &mh) {
809
810 if (cmsg->cmsg_level == IPPROTO_IPV6) {
811 assert(p->family == AF_INET6);
812
813 switch (cmsg->cmsg_type) {
814
815 case IPV6_PKTINFO: {
816 struct in6_pktinfo *i = (struct in6_pktinfo*) CMSG_DATA(cmsg);
817
818 if (p->ifindex <= 0)
819 p->ifindex = i->ipi6_ifindex;
820
821 p->destination.in6 = i->ipi6_addr;
822 break;
823 }
824
825 case IPV6_HOPLIMIT:
826 p->ttl = *(int *) CMSG_DATA(cmsg);
827 break;
828
829 case IPV6_RECVFRAGSIZE:
830 p->fragsize = *(int *) CMSG_DATA(cmsg);
831 break;
832 }
833 } else if (cmsg->cmsg_level == IPPROTO_IP) {
834 assert(p->family == AF_INET);
835
836 switch (cmsg->cmsg_type) {
837
838 case IP_PKTINFO: {
839 struct in_pktinfo *i = (struct in_pktinfo*) CMSG_DATA(cmsg);
840
841 if (p->ifindex <= 0)
842 p->ifindex = i->ipi_ifindex;
843
844 p->destination.in = i->ipi_addr;
845 break;
846 }
847
848 case IP_TTL:
849 p->ttl = *(int *) CMSG_DATA(cmsg);
850 break;
851
852 case IP_RECVFRAGSIZE:
853 p->fragsize = *(int *) CMSG_DATA(cmsg);
854 break;
855 }
856 }
857 }
858
859 /* The Linux kernel sets the interface index to the loopback
860 * device if the packet came from the local host since it
861 * avoids the routing table in such a case. Let's unset the
862 * interface index in such a case. */
863 if (p->ifindex == LOOPBACK_IFINDEX)
864 p->ifindex = 0;
865
866 if (protocol != DNS_PROTOCOL_DNS) {
867 /* If we don't know the interface index still, we look for the
868 * first local interface with a matching address. Yuck! */
869 if (p->ifindex <= 0)
870 p->ifindex = manager_find_ifindex(m, p->family, &p->destination);
871 }
872
873 if (DEBUG_LOGGING) {
874 _cleanup_free_ char *sender_address = NULL, *destination_address = NULL;
875
876 (void) in_addr_to_string(p->family, &p->sender, &sender_address);
877 (void) in_addr_to_string(p->family, &p->destination, &destination_address);
878
879 log_debug("Received %s UDP packet of size %zu, ifindex=%i, ttl=%i, fragsize=%zu, sender=%s, destination=%s",
880 dns_protocol_to_string(protocol), p->size, p->ifindex, p->ttl, p->fragsize,
881 strna(sender_address), strna(destination_address));
882 }
883
884 *ret = TAKE_PTR(p);
885 return 1;
886 }
887
sendmsg_loop(int fd,struct msghdr * mh,int flags)888 static int sendmsg_loop(int fd, struct msghdr *mh, int flags) {
889 int r;
890
891 assert(fd >= 0);
892 assert(mh);
893
894 for (;;) {
895 if (sendmsg(fd, mh, flags) >= 0)
896 return 0;
897
898 if (errno == EINTR)
899 continue;
900
901 if (errno != EAGAIN)
902 return -errno;
903
904 r = fd_wait_for_event(fd, POLLOUT, SEND_TIMEOUT_USEC);
905 if (r < 0)
906 return r;
907 if (r == 0)
908 return -ETIMEDOUT;
909 }
910 }
911
write_loop(int fd,void * message,size_t length)912 static int write_loop(int fd, void *message, size_t length) {
913 int r;
914
915 assert(fd >= 0);
916 assert(message);
917
918 for (;;) {
919 if (write(fd, message, length) >= 0)
920 return 0;
921
922 if (errno == EINTR)
923 continue;
924
925 if (errno != EAGAIN)
926 return -errno;
927
928 r = fd_wait_for_event(fd, POLLOUT, SEND_TIMEOUT_USEC);
929 if (r < 0)
930 return r;
931 if (r == 0)
932 return -ETIMEDOUT;
933 }
934 }
935
manager_write(Manager * m,int fd,DnsPacket * p)936 int manager_write(Manager *m, int fd, DnsPacket *p) {
937 int r;
938
939 log_debug("Sending %s%s packet with id %" PRIu16 " of size %zu.",
940 DNS_PACKET_TC(p) ? "truncated (!) " : "",
941 DNS_PACKET_QR(p) ? "response" : "query",
942 DNS_PACKET_ID(p),
943 p->size);
944
945 r = write_loop(fd, DNS_PACKET_DATA(p), p->size);
946 if (r < 0)
947 return r;
948
949 return 0;
950 }
951
manager_ipv4_send(Manager * m,int fd,int ifindex,const struct in_addr * destination,uint16_t port,const struct in_addr * source,DnsPacket * p)952 static int manager_ipv4_send(
953 Manager *m,
954 int fd,
955 int ifindex,
956 const struct in_addr *destination,
957 uint16_t port,
958 const struct in_addr *source,
959 DnsPacket *p) {
960
961 CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in_pktinfo))) control = {};
962 union sockaddr_union sa;
963 struct iovec iov;
964 struct msghdr mh = {
965 .msg_iov = &iov,
966 .msg_iovlen = 1,
967 .msg_name = &sa.sa,
968 .msg_namelen = sizeof(sa.in),
969 };
970
971 assert(m);
972 assert(fd >= 0);
973 assert(destination);
974 assert(port > 0);
975 assert(p);
976
977 iov = IOVEC_MAKE(DNS_PACKET_DATA(p), p->size);
978
979 sa = (union sockaddr_union) {
980 .in.sin_family = AF_INET,
981 .in.sin_addr = *destination,
982 .in.sin_port = htobe16(port),
983 };
984
985 if (ifindex > 0) {
986 struct cmsghdr *cmsg;
987 struct in_pktinfo *pi;
988
989 mh.msg_control = &control;
990 mh.msg_controllen = sizeof(control);
991
992 cmsg = CMSG_FIRSTHDR(&mh);
993 cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
994 cmsg->cmsg_level = IPPROTO_IP;
995 cmsg->cmsg_type = IP_PKTINFO;
996
997 pi = (struct in_pktinfo*) CMSG_DATA(cmsg);
998 pi->ipi_ifindex = ifindex;
999
1000 if (source)
1001 pi->ipi_spec_dst = *source;
1002 }
1003
1004 return sendmsg_loop(fd, &mh, 0);
1005 }
1006
manager_ipv6_send(Manager * m,int fd,int ifindex,const struct in6_addr * destination,uint16_t port,const struct in6_addr * source,DnsPacket * p)1007 static int manager_ipv6_send(
1008 Manager *m,
1009 int fd,
1010 int ifindex,
1011 const struct in6_addr *destination,
1012 uint16_t port,
1013 const struct in6_addr *source,
1014 DnsPacket *p) {
1015
1016 CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct in6_pktinfo))) control = {};
1017 union sockaddr_union sa;
1018 struct iovec iov;
1019 struct msghdr mh = {
1020 .msg_iov = &iov,
1021 .msg_iovlen = 1,
1022 .msg_name = &sa.sa,
1023 .msg_namelen = sizeof(sa.in6),
1024 };
1025
1026 assert(m);
1027 assert(fd >= 0);
1028 assert(destination);
1029 assert(port > 0);
1030 assert(p);
1031
1032 iov = IOVEC_MAKE(DNS_PACKET_DATA(p), p->size);
1033
1034 sa = (union sockaddr_union) {
1035 .in6.sin6_family = AF_INET6,
1036 .in6.sin6_addr = *destination,
1037 .in6.sin6_port = htobe16(port),
1038 .in6.sin6_scope_id = ifindex,
1039 };
1040
1041 if (ifindex > 0) {
1042 struct cmsghdr *cmsg;
1043 struct in6_pktinfo *pi;
1044
1045 mh.msg_control = &control;
1046 mh.msg_controllen = sizeof(control);
1047
1048 cmsg = CMSG_FIRSTHDR(&mh);
1049 cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
1050 cmsg->cmsg_level = IPPROTO_IPV6;
1051 cmsg->cmsg_type = IPV6_PKTINFO;
1052
1053 pi = (struct in6_pktinfo*) CMSG_DATA(cmsg);
1054 pi->ipi6_ifindex = ifindex;
1055
1056 if (source)
1057 pi->ipi6_addr = *source;
1058 }
1059
1060 return sendmsg_loop(fd, &mh, 0);
1061 }
1062
manager_send(Manager * m,int fd,int ifindex,int family,const union in_addr_union * destination,uint16_t port,const union in_addr_union * source,DnsPacket * p)1063 int manager_send(
1064 Manager *m,
1065 int fd,
1066 int ifindex,
1067 int family,
1068 const union in_addr_union *destination,
1069 uint16_t port,
1070 const union in_addr_union *source,
1071 DnsPacket *p) {
1072
1073 assert(m);
1074 assert(fd >= 0);
1075 assert(destination);
1076 assert(port > 0);
1077 assert(p);
1078
1079 log_debug("Sending %s%s packet with id %" PRIu16 " on interface %i/%s of size %zu.",
1080 DNS_PACKET_TC(p) ? "truncated (!) " : "",
1081 DNS_PACKET_QR(p) ? "response" : "query",
1082 DNS_PACKET_ID(p),
1083 ifindex, af_to_name(family),
1084 p->size);
1085
1086 if (family == AF_INET)
1087 return manager_ipv4_send(m, fd, ifindex, &destination->in, port, source ? &source->in : NULL, p);
1088 if (family == AF_INET6)
1089 return manager_ipv6_send(m, fd, ifindex, &destination->in6, port, source ? &source->in6 : NULL, p);
1090
1091 return -EAFNOSUPPORT;
1092 }
1093
manager_find_mtu(Manager * m)1094 uint32_t manager_find_mtu(Manager *m) {
1095 uint32_t mtu = 0;
1096 Link *l;
1097
1098 /* If we don't know on which link a DNS packet would be delivered, let's find the largest MTU that
1099 * works on all interfaces we know of that have an IP address associated */
1100
1101 HASHMAP_FOREACH(l, m->links) {
1102 /* Let's filter out links without IP addresses (e.g. AF_CAN links and suchlike) */
1103 if (!l->addresses)
1104 continue;
1105
1106 /* Safety check: MTU shorter than what we need for the absolutely shortest DNS request? Then
1107 * let's ignore this link. */
1108 if (l->mtu < MIN(UDP4_PACKET_HEADER_SIZE + DNS_PACKET_HEADER_SIZE,
1109 UDP6_PACKET_HEADER_SIZE + DNS_PACKET_HEADER_SIZE))
1110 continue;
1111
1112 if (mtu <= 0 || l->mtu < mtu)
1113 mtu = l->mtu;
1114 }
1115
1116 if (mtu == 0) /* found nothing? then let's assume the typical Ethernet MTU for lack of anything more precise */
1117 return 1500;
1118
1119 return mtu;
1120 }
1121
manager_find_ifindex(Manager * m,int family,const union in_addr_union * in_addr)1122 int manager_find_ifindex(Manager *m, int family, const union in_addr_union *in_addr) {
1123 LinkAddress *a;
1124
1125 assert(m);
1126
1127 if (!IN_SET(family, AF_INET, AF_INET6))
1128 return 0;
1129
1130 if (!in_addr)
1131 return 0;
1132
1133 a = manager_find_link_address(m, family, in_addr);
1134 if (a)
1135 return a->link->ifindex;
1136
1137 return 0;
1138 }
1139
manager_refresh_rrs(Manager * m)1140 void manager_refresh_rrs(Manager *m) {
1141 Link *l;
1142 DnssdService *s;
1143
1144 assert(m);
1145
1146 m->llmnr_host_ipv4_key = dns_resource_key_unref(m->llmnr_host_ipv4_key);
1147 m->llmnr_host_ipv6_key = dns_resource_key_unref(m->llmnr_host_ipv6_key);
1148 m->mdns_host_ipv4_key = dns_resource_key_unref(m->mdns_host_ipv4_key);
1149 m->mdns_host_ipv6_key = dns_resource_key_unref(m->mdns_host_ipv6_key);
1150
1151 HASHMAP_FOREACH(l, m->links)
1152 link_add_rrs(l, true);
1153
1154 if (m->mdns_support == RESOLVE_SUPPORT_YES)
1155 HASHMAP_FOREACH(s, m->dnssd_services)
1156 if (dnssd_update_rrs(s) < 0)
1157 log_warning("Failed to refresh DNS-SD service '%s'", s->name);
1158
1159 HASHMAP_FOREACH(l, m->links)
1160 link_add_rrs(l, false);
1161 }
1162
manager_next_random_name(const char * old,char ** ret_new)1163 static int manager_next_random_name(const char *old, char **ret_new) {
1164 const char *p;
1165 uint64_t u, a;
1166 char *n;
1167
1168 p = strchr(old, 0);
1169 assert(p);
1170
1171 while (p > old) {
1172 if (!strchr(DIGITS, p[-1]))
1173 break;
1174
1175 p--;
1176 }
1177
1178 if (*p == 0 || safe_atou64(p, &u) < 0 || u <= 0)
1179 u = 1;
1180
1181 /* Add a random number to the old value. This way we can avoid
1182 * that two hosts pick the same hostname, win on IPv4 and lose
1183 * on IPv6 (or vice versa), and pick the same hostname
1184 * replacement hostname, ad infinitum. We still want the
1185 * numbers to go up monotonically, hence we just add a random
1186 * value 1..10 */
1187
1188 random_bytes(&a, sizeof(a));
1189 u += 1 + a % 10;
1190
1191 if (asprintf(&n, "%.*s%" PRIu64, (int) (p - old), old, u) < 0)
1192 return -ENOMEM;
1193
1194 *ret_new = n;
1195
1196 return 0;
1197 }
1198
manager_next_hostname(Manager * m)1199 int manager_next_hostname(Manager *m) {
1200 _cleanup_free_ char *h = NULL, *k = NULL;
1201 int r;
1202
1203 assert(m);
1204
1205 r = manager_next_random_name(m->llmnr_hostname, &h);
1206 if (r < 0)
1207 return r;
1208
1209 r = dns_name_concat(h, "local", 0, &k);
1210 if (r < 0)
1211 return r;
1212
1213 log_info("Hostname conflict, changing published hostname from '%s' to '%s'.", m->llmnr_hostname, h);
1214
1215 free_and_replace(m->llmnr_hostname, h);
1216 free_and_replace(m->mdns_hostname, k);
1217
1218 manager_refresh_rrs(m);
1219 (void) manager_send_changed(m, "LLMNRHostname");
1220
1221 return 0;
1222 }
1223
manager_find_link_address(Manager * m,int family,const union in_addr_union * in_addr)1224 LinkAddress* manager_find_link_address(Manager *m, int family, const union in_addr_union *in_addr) {
1225 Link *l;
1226
1227 assert(m);
1228
1229 if (!IN_SET(family, AF_INET, AF_INET6))
1230 return NULL;
1231
1232 if (!in_addr)
1233 return NULL;
1234
1235 HASHMAP_FOREACH(l, m->links) {
1236 LinkAddress *a;
1237
1238 a = link_find_address(l, family, in_addr);
1239 if (a)
1240 return a;
1241 }
1242
1243 return NULL;
1244 }
1245
manager_packet_from_local_address(Manager * m,DnsPacket * p)1246 bool manager_packet_from_local_address(Manager *m, DnsPacket *p) {
1247 assert(m);
1248 assert(p);
1249
1250 /* Let's see if this packet comes from an IP address we have on any local interface */
1251
1252 return !!manager_find_link_address(m, p->family, &p->sender);
1253 }
1254
manager_packet_from_our_transaction(Manager * m,DnsPacket * p)1255 bool manager_packet_from_our_transaction(Manager *m, DnsPacket *p) {
1256 DnsTransaction *t;
1257
1258 assert(m);
1259 assert(p);
1260
1261 /* Let's see if we have a transaction with a query message with the exact same binary contents as the
1262 * one we just got. If so, it's almost definitely a packet loop of some kind. */
1263
1264 t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
1265 if (!t)
1266 return false;
1267
1268 return t->sent && dns_packet_equal(t->sent, p);
1269 }
1270
manager_find_scope(Manager * m,DnsPacket * p)1271 DnsScope* manager_find_scope(Manager *m, DnsPacket *p) {
1272 Link *l;
1273
1274 assert(m);
1275 assert(p);
1276
1277 l = hashmap_get(m->links, INT_TO_PTR(p->ifindex));
1278 if (!l)
1279 return NULL;
1280
1281 switch (p->protocol) {
1282 case DNS_PROTOCOL_LLMNR:
1283 if (p->family == AF_INET)
1284 return l->llmnr_ipv4_scope;
1285 else if (p->family == AF_INET6)
1286 return l->llmnr_ipv6_scope;
1287
1288 break;
1289
1290 case DNS_PROTOCOL_MDNS:
1291 if (p->family == AF_INET)
1292 return l->mdns_ipv4_scope;
1293 else if (p->family == AF_INET6)
1294 return l->mdns_ipv6_scope;
1295
1296 break;
1297
1298 default:
1299 break;
1300 }
1301
1302 return NULL;
1303 }
1304
manager_verify_all(Manager * m)1305 void manager_verify_all(Manager *m) {
1306 assert(m);
1307
1308 LIST_FOREACH(scopes, s, m->dns_scopes)
1309 dns_zone_verify_all(&s->zone);
1310 }
1311
manager_is_own_hostname(Manager * m,const char * name)1312 int manager_is_own_hostname(Manager *m, const char *name) {
1313 int r;
1314
1315 assert(m);
1316 assert(name);
1317
1318 if (m->llmnr_hostname) {
1319 r = dns_name_equal(name, m->llmnr_hostname);
1320 if (r != 0)
1321 return r;
1322 }
1323
1324 if (m->mdns_hostname) {
1325 r = dns_name_equal(name, m->mdns_hostname);
1326 if (r != 0)
1327 return r;
1328 }
1329
1330 if (m->full_hostname)
1331 return dns_name_equal(name, m->full_hostname);
1332
1333 return 0;
1334 }
1335
manager_compile_dns_servers(Manager * m,OrderedSet ** dns)1336 int manager_compile_dns_servers(Manager *m, OrderedSet **dns) {
1337 Link *l;
1338 int r;
1339
1340 assert(m);
1341 assert(dns);
1342
1343 r = ordered_set_ensure_allocated(dns, &dns_server_hash_ops);
1344 if (r < 0)
1345 return r;
1346
1347 /* First add the system-wide servers and domains */
1348 LIST_FOREACH(servers, s, m->dns_servers) {
1349 r = ordered_set_put(*dns, s);
1350 if (r == -EEXIST)
1351 continue;
1352 if (r < 0)
1353 return r;
1354 }
1355
1356 /* Then, add the per-link servers */
1357 HASHMAP_FOREACH(l, m->links) {
1358 LIST_FOREACH(servers, s, l->dns_servers) {
1359 r = ordered_set_put(*dns, s);
1360 if (r == -EEXIST)
1361 continue;
1362 if (r < 0)
1363 return r;
1364 }
1365 }
1366
1367 /* If we found nothing, add the fallback servers */
1368 if (ordered_set_isempty(*dns)) {
1369 LIST_FOREACH(servers, s, m->fallback_dns_servers) {
1370 r = ordered_set_put(*dns, s);
1371 if (r == -EEXIST)
1372 continue;
1373 if (r < 0)
1374 return r;
1375 }
1376 }
1377
1378 return 0;
1379 }
1380
1381 /* filter_route is a tri-state:
1382 * < 0: no filtering
1383 * = 0 or false: return only domains which should be used for searching
1384 * > 0 or true: return only domains which are for routing only
1385 */
manager_compile_search_domains(Manager * m,OrderedSet ** domains,int filter_route)1386 int manager_compile_search_domains(Manager *m, OrderedSet **domains, int filter_route) {
1387 Link *l;
1388 int r;
1389
1390 assert(m);
1391 assert(domains);
1392
1393 r = ordered_set_ensure_allocated(domains, &dns_name_hash_ops);
1394 if (r < 0)
1395 return r;
1396
1397 LIST_FOREACH(domains, d, m->search_domains) {
1398
1399 if (filter_route >= 0 &&
1400 d->route_only != !!filter_route)
1401 continue;
1402
1403 r = ordered_set_put(*domains, d->name);
1404 if (r == -EEXIST)
1405 continue;
1406 if (r < 0)
1407 return r;
1408 }
1409
1410 HASHMAP_FOREACH(l, m->links) {
1411
1412 LIST_FOREACH(domains, d, l->search_domains) {
1413
1414 if (filter_route >= 0 &&
1415 d->route_only != !!filter_route)
1416 continue;
1417
1418 r = ordered_set_put(*domains, d->name);
1419 if (r == -EEXIST)
1420 continue;
1421 if (r < 0)
1422 return r;
1423 }
1424 }
1425
1426 return 0;
1427 }
1428
manager_get_dnssec_mode(Manager * m)1429 DnssecMode manager_get_dnssec_mode(Manager *m) {
1430 assert(m);
1431
1432 if (m->dnssec_mode != _DNSSEC_MODE_INVALID)
1433 return m->dnssec_mode;
1434
1435 return DNSSEC_NO;
1436 }
1437
manager_dnssec_supported(Manager * m)1438 bool manager_dnssec_supported(Manager *m) {
1439 DnsServer *server;
1440 Link *l;
1441
1442 assert(m);
1443
1444 if (manager_get_dnssec_mode(m) == DNSSEC_NO)
1445 return false;
1446
1447 server = manager_get_dns_server(m);
1448 if (server && !dns_server_dnssec_supported(server))
1449 return false;
1450
1451 HASHMAP_FOREACH(l, m->links)
1452 if (!link_dnssec_supported(l))
1453 return false;
1454
1455 return true;
1456 }
1457
manager_get_dns_over_tls_mode(Manager * m)1458 DnsOverTlsMode manager_get_dns_over_tls_mode(Manager *m) {
1459 assert(m);
1460
1461 if (m->dns_over_tls_mode != _DNS_OVER_TLS_MODE_INVALID)
1462 return m->dns_over_tls_mode;
1463
1464 return DNS_OVER_TLS_NO;
1465 }
1466
manager_dnssec_verdict(Manager * m,DnssecVerdict verdict,const DnsResourceKey * key)1467 void manager_dnssec_verdict(Manager *m, DnssecVerdict verdict, const DnsResourceKey *key) {
1468
1469 assert(verdict >= 0);
1470 assert(verdict < _DNSSEC_VERDICT_MAX);
1471
1472 if (DEBUG_LOGGING) {
1473 char s[DNS_RESOURCE_KEY_STRING_MAX];
1474
1475 log_debug("Found verdict for lookup %s: %s",
1476 dns_resource_key_to_string(key, s, sizeof s),
1477 dnssec_verdict_to_string(verdict));
1478 }
1479
1480 m->n_dnssec_verdict[verdict]++;
1481 }
1482
manager_routable(Manager * m)1483 bool manager_routable(Manager *m) {
1484 Link *l;
1485
1486 assert(m);
1487
1488 /* Returns true if the host has at least one interface with a routable address (regardless if IPv4 or IPv6) */
1489
1490 HASHMAP_FOREACH(l, m->links)
1491 if (link_relevant(l, AF_UNSPEC, false))
1492 return true;
1493
1494 return false;
1495 }
1496
manager_flush_caches(Manager * m,int log_level)1497 void manager_flush_caches(Manager *m, int log_level) {
1498 assert(m);
1499
1500 LIST_FOREACH(scopes, scope, m->dns_scopes)
1501 dns_cache_flush(&scope->cache);
1502
1503 log_full(log_level, "Flushed all caches.");
1504 }
1505
manager_reset_server_features(Manager * m)1506 void manager_reset_server_features(Manager *m) {
1507 Link *l;
1508
1509 dns_server_reset_features_all(m->dns_servers);
1510 dns_server_reset_features_all(m->fallback_dns_servers);
1511
1512 HASHMAP_FOREACH(l, m->links)
1513 dns_server_reset_features_all(l->dns_servers);
1514
1515 log_info("Resetting learnt feature levels on all servers.");
1516 }
1517
manager_cleanup_saved_user(Manager * m)1518 void manager_cleanup_saved_user(Manager *m) {
1519 _cleanup_closedir_ DIR *d = NULL;
1520
1521 assert(m);
1522
1523 /* Clean up all saved per-link files in /run/systemd/resolve/netif/ that don't have a matching interface
1524 * anymore. These files are created to persist settings pushed in by the user via the bus, so that resolved can
1525 * be restarted without losing this data. */
1526
1527 d = opendir("/run/systemd/resolve/netif/");
1528 if (!d) {
1529 if (errno == ENOENT)
1530 return;
1531
1532 log_warning_errno(errno, "Failed to open interface directory: %m");
1533 return;
1534 }
1535
1536 FOREACH_DIRENT_ALL(de, d, log_error_errno(errno, "Failed to read interface directory: %m")) {
1537 _cleanup_free_ char *p = NULL;
1538 int ifindex;
1539 Link *l;
1540
1541 if (!IN_SET(de->d_type, DT_UNKNOWN, DT_REG))
1542 continue;
1543
1544 if (dot_or_dot_dot(de->d_name))
1545 continue;
1546
1547 ifindex = parse_ifindex(de->d_name);
1548 if (ifindex < 0) /* Probably some temporary file from a previous run. Delete it */
1549 goto rm;
1550
1551 l = hashmap_get(m->links, INT_TO_PTR(ifindex));
1552 if (!l) /* link vanished */
1553 goto rm;
1554
1555 if (l->is_managed) /* now managed by networkd, hence the bus settings are useless */
1556 goto rm;
1557
1558 continue;
1559
1560 rm:
1561 p = path_join("/run/systemd/resolve/netif", de->d_name);
1562 if (!p) {
1563 log_oom();
1564 return;
1565 }
1566
1567 (void) unlink(p);
1568 }
1569 }
1570
manager_next_dnssd_names(Manager * m)1571 bool manager_next_dnssd_names(Manager *m) {
1572 DnssdService *s;
1573 bool tried = false;
1574 int r;
1575
1576 assert(m);
1577
1578 HASHMAP_FOREACH(s, m->dnssd_services) {
1579 _cleanup_free_ char * new_name = NULL;
1580
1581 if (!s->withdrawn)
1582 continue;
1583
1584 r = manager_next_random_name(s->name_template, &new_name);
1585 if (r < 0) {
1586 log_warning_errno(r, "Failed to get new name for service '%s': %m", s->name);
1587 continue;
1588 }
1589
1590 free_and_replace(s->name_template, new_name);
1591
1592 s->withdrawn = false;
1593
1594 tried = true;
1595 }
1596
1597 if (tried)
1598 manager_refresh_rrs(m);
1599
1600 return tried;
1601 }
1602
manager_server_is_stub(Manager * m,DnsServer * s)1603 bool manager_server_is_stub(Manager *m, DnsServer *s) {
1604 DnsStubListenerExtra *l;
1605
1606 assert(m);
1607 assert(s);
1608
1609 /* Safety check: we generally already skip the main stub when parsing configuration. But let's be
1610 * extra careful, and check here again */
1611 if (s->family == AF_INET &&
1612 s->address.in.s_addr == htobe32(INADDR_DNS_STUB) &&
1613 dns_server_port(s) == 53)
1614 return true;
1615
1616 /* Main reason to call this is to check server data against the extra listeners, and filter things
1617 * out. */
1618 ORDERED_SET_FOREACH(l, m->dns_extra_stub_listeners)
1619 if (s->family == l->family &&
1620 in_addr_equal(s->family, &s->address, &l->address) &&
1621 dns_server_port(s) == dns_stub_listener_extra_port(l))
1622 return true;
1623
1624 return false;
1625 }
1626
socket_disable_pmtud(int fd,int af)1627 int socket_disable_pmtud(int fd, int af) {
1628 int r;
1629
1630 assert(fd >= 0);
1631
1632 if (af == AF_UNSPEC) {
1633 r = socket_get_family(fd, &af);
1634 if (r < 0)
1635 return r;
1636 }
1637
1638 switch (af) {
1639
1640 case AF_INET: {
1641 /* Turn off path MTU discovery, let's rather fragment on the way than to open us up against
1642 * PMTU forgery vulnerabilities.
1643 *
1644 * There appears to be no documentation about IP_PMTUDISC_OMIT, but it has the effect that
1645 * the "Don't Fragment" bit in the IPv4 header is turned off, thus enforcing fragmentation if
1646 * our datagram size exceeds the MTU of a router in the path, and turning off path MTU
1647 * discovery.
1648 *
1649 * This helps mitigating the PMTUD vulnerability described here:
1650 *
1651 * https://blog.apnic.net/2019/07/12/its-time-to-consider-avoiding-ip-fragmentation-in-the-dns/
1652 *
1653 * Similar logic is in place in most DNS servers.
1654 *
1655 * There are multiple conflicting goals: we want to allow the largest datagrams possible (for
1656 * efficiency reasons), but not have fragmentation (for security reasons), nor use PMTUD (for
1657 * security reasons, too). Our strategy to deal with this is: use large packets, turn off
1658 * PMTUD, but watch fragmentation taking place, and then size our packets to the max of the
1659 * fragments seen — and if we need larger packets always go to TCP.
1660 */
1661
1662 r = setsockopt_int(fd, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_OMIT);
1663 if (r < 0)
1664 return r;
1665
1666 return 0;
1667 }
1668
1669 case AF_INET6: {
1670 /* On IPv6 fragmentation only is done by the sender — never by routers on the path. PMTUD is
1671 * mandatory. If we want to turn off PMTUD, the only way is by sending with minimal MTU only,
1672 * so that we apply maximum fragmentation locally already, and thus PMTUD doesn't happen
1673 * because there's nothing that could be fragmented further anymore. */
1674
1675 r = setsockopt_int(fd, IPPROTO_IPV6, IPV6_MTU, IPV6_MIN_MTU);
1676 if (r < 0)
1677 return r;
1678
1679 return 0;
1680 }
1681
1682 default:
1683 return -EAFNOSUPPORT;
1684 }
1685 }
1686