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1 | /*** | |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright 2014 Lennart Poettering | |
5 | ||
6 | systemd is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU Lesser General Public License as published by | |
8 | the Free Software Foundation; either version 2.1 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | systemd is distributed in the hope that it will be useful, but | |
12 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public License | |
17 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
18 | ***/ | |
19 | ||
20 | #include <sd-messages.h> | |
21 | ||
22 | #include "af-list.h" | |
23 | #include "alloc-util.h" | |
24 | #include "dns-domain.h" | |
25 | #include "errno-list.h" | |
26 | #include "fd-util.h" | |
27 | #include "random-util.h" | |
28 | #include "resolved-dns-cache.h" | |
29 | #include "resolved-dns-transaction.h" | |
30 | #include "resolved-llmnr.h" | |
31 | #include "string-table.h" | |
32 | ||
33 | #define TRANSACTIONS_MAX 4096 | |
34 | ||
35 | static void dns_transaction_reset_answer(DnsTransaction *t) { | |
36 | assert(t); | |
37 | ||
38 | t->received = dns_packet_unref(t->received); | |
39 | t->answer = dns_answer_unref(t->answer); | |
40 | t->answer_rcode = 0; | |
41 | t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; | |
42 | t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID; | |
43 | t->answer_authenticated = false; | |
44 | t->answer_nsec_ttl = (uint32_t) -1; | |
45 | t->answer_errno = 0; | |
46 | } | |
47 | ||
48 | static void dns_transaction_flush_dnssec_transactions(DnsTransaction *t) { | |
49 | DnsTransaction *z; | |
50 | ||
51 | assert(t); | |
52 | ||
53 | while ((z = set_steal_first(t->dnssec_transactions))) { | |
54 | set_remove(z->notify_transactions, t); | |
55 | set_remove(z->notify_transactions_done, t); | |
56 | dns_transaction_gc(z); | |
57 | } | |
58 | } | |
59 | ||
60 | static void dns_transaction_close_connection(DnsTransaction *t) { | |
61 | assert(t); | |
62 | ||
63 | if (t->stream) { | |
64 | /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */ | |
65 | t->stream->complete = NULL; | |
66 | t->stream->on_packet = NULL; | |
67 | t->stream->transaction = NULL; | |
68 | t->stream = dns_stream_unref(t->stream); | |
69 | } | |
70 | ||
71 | t->dns_udp_event_source = sd_event_source_unref(t->dns_udp_event_source); | |
72 | t->dns_udp_fd = safe_close(t->dns_udp_fd); | |
73 | } | |
74 | ||
75 | static void dns_transaction_stop_timeout(DnsTransaction *t) { | |
76 | assert(t); | |
77 | ||
78 | t->timeout_event_source = sd_event_source_unref(t->timeout_event_source); | |
79 | } | |
80 | ||
81 | DnsTransaction* dns_transaction_free(DnsTransaction *t) { | |
82 | DnsQueryCandidate *c; | |
83 | DnsZoneItem *i; | |
84 | DnsTransaction *z; | |
85 | ||
86 | if (!t) | |
87 | return NULL; | |
88 | ||
89 | log_debug("Freeing transaction %" PRIu16 ".", t->id); | |
90 | ||
91 | dns_transaction_close_connection(t); | |
92 | dns_transaction_stop_timeout(t); | |
93 | ||
94 | dns_packet_unref(t->sent); | |
95 | dns_transaction_reset_answer(t); | |
96 | ||
97 | dns_server_unref(t->server); | |
98 | ||
99 | if (t->scope) { | |
100 | hashmap_remove_value(t->scope->transactions_by_key, t->key, t); | |
101 | LIST_REMOVE(transactions_by_scope, t->scope->transactions, t); | |
102 | ||
103 | if (t->id != 0) | |
104 | hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id)); | |
105 | } | |
106 | ||
107 | while ((c = set_steal_first(t->notify_query_candidates))) | |
108 | set_remove(c->transactions, t); | |
109 | set_free(t->notify_query_candidates); | |
110 | ||
111 | while ((c = set_steal_first(t->notify_query_candidates_done))) | |
112 | set_remove(c->transactions, t); | |
113 | set_free(t->notify_query_candidates_done); | |
114 | ||
115 | while ((i = set_steal_first(t->notify_zone_items))) | |
116 | i->probe_transaction = NULL; | |
117 | set_free(t->notify_zone_items); | |
118 | ||
119 | while ((i = set_steal_first(t->notify_zone_items_done))) | |
120 | i->probe_transaction = NULL; | |
121 | set_free(t->notify_zone_items_done); | |
122 | ||
123 | while ((z = set_steal_first(t->notify_transactions))) | |
124 | set_remove(z->dnssec_transactions, t); | |
125 | set_free(t->notify_transactions); | |
126 | ||
127 | while ((z = set_steal_first(t->notify_transactions_done))) | |
128 | set_remove(z->dnssec_transactions, t); | |
129 | set_free(t->notify_transactions_done); | |
130 | ||
131 | dns_transaction_flush_dnssec_transactions(t); | |
132 | set_free(t->dnssec_transactions); | |
133 | ||
134 | dns_answer_unref(t->validated_keys); | |
135 | dns_resource_key_unref(t->key); | |
136 | ||
137 | free(t); | |
138 | return NULL; | |
139 | } | |
140 | ||
141 | DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free); | |
142 | ||
143 | bool dns_transaction_gc(DnsTransaction *t) { | |
144 | assert(t); | |
145 | ||
146 | if (t->block_gc > 0) | |
147 | return true; | |
148 | ||
149 | if (set_isempty(t->notify_query_candidates) && | |
150 | set_isempty(t->notify_query_candidates_done) && | |
151 | set_isempty(t->notify_zone_items) && | |
152 | set_isempty(t->notify_zone_items_done) && | |
153 | set_isempty(t->notify_transactions) && | |
154 | set_isempty(t->notify_transactions_done)) { | |
155 | dns_transaction_free(t); | |
156 | return false; | |
157 | } | |
158 | ||
159 | return true; | |
160 | } | |
161 | ||
162 | static uint16_t pick_new_id(Manager *m) { | |
163 | uint16_t new_id; | |
164 | ||
165 | /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the number of | |
166 | * transactions, and it's much lower than the space of IDs. */ | |
167 | ||
168 | assert_cc(TRANSACTIONS_MAX < 0xFFFF); | |
169 | ||
170 | do | |
171 | random_bytes(&new_id, sizeof(new_id)); | |
172 | while (new_id == 0 || | |
173 | hashmap_get(m->dns_transactions, UINT_TO_PTR(new_id))); | |
174 | ||
175 | return new_id; | |
176 | } | |
177 | ||
178 | int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) { | |
179 | _cleanup_(dns_transaction_freep) DnsTransaction *t = NULL; | |
180 | int r; | |
181 | ||
182 | assert(ret); | |
183 | assert(s); | |
184 | assert(key); | |
185 | ||
186 | /* Don't allow looking up invalid or pseudo RRs */ | |
187 | if (!dns_type_is_valid_query(key->type)) | |
188 | return -EINVAL; | |
189 | if (dns_type_is_obsolete(key->type)) | |
190 | return -EOPNOTSUPP; | |
191 | ||
192 | /* We only support the IN class */ | |
193 | if (key->class != DNS_CLASS_IN && key->class != DNS_CLASS_ANY) | |
194 | return -EOPNOTSUPP; | |
195 | ||
196 | if (hashmap_size(s->manager->dns_transactions) >= TRANSACTIONS_MAX) | |
197 | return -EBUSY; | |
198 | ||
199 | r = hashmap_ensure_allocated(&s->manager->dns_transactions, NULL); | |
200 | if (r < 0) | |
201 | return r; | |
202 | ||
203 | r = hashmap_ensure_allocated(&s->transactions_by_key, &dns_resource_key_hash_ops); | |
204 | if (r < 0) | |
205 | return r; | |
206 | ||
207 | t = new0(DnsTransaction, 1); | |
208 | if (!t) | |
209 | return -ENOMEM; | |
210 | ||
211 | t->dns_udp_fd = -1; | |
212 | t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID; | |
213 | t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; | |
214 | t->answer_nsec_ttl = (uint32_t) -1; | |
215 | t->key = dns_resource_key_ref(key); | |
216 | t->current_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID; | |
217 | ||
218 | t->id = pick_new_id(s->manager); | |
219 | ||
220 | r = hashmap_put(s->manager->dns_transactions, UINT_TO_PTR(t->id), t); | |
221 | if (r < 0) { | |
222 | t->id = 0; | |
223 | return r; | |
224 | } | |
225 | ||
226 | r = hashmap_replace(s->transactions_by_key, t->key, t); | |
227 | if (r < 0) { | |
228 | hashmap_remove(s->manager->dns_transactions, UINT_TO_PTR(t->id)); | |
229 | return r; | |
230 | } | |
231 | ||
232 | LIST_PREPEND(transactions_by_scope, s->transactions, t); | |
233 | t->scope = s; | |
234 | ||
235 | s->manager->n_transactions_total++; | |
236 | ||
237 | if (ret) | |
238 | *ret = t; | |
239 | ||
240 | t = NULL; | |
241 | ||
242 | return 0; | |
243 | } | |
244 | ||
245 | static void dns_transaction_shuffle_id(DnsTransaction *t) { | |
246 | uint16_t new_id; | |
247 | assert(t); | |
248 | ||
249 | /* Pick a new ID for this transaction. */ | |
250 | ||
251 | new_id = pick_new_id(t->scope->manager); | |
252 | assert_se(hashmap_remove_and_put(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id), UINT_TO_PTR(new_id), t) >= 0); | |
253 | ||
254 | log_debug("Transaction %" PRIu16 " is now %" PRIu16 ".", t->id, new_id); | |
255 | t->id = new_id; | |
256 | ||
257 | /* Make sure we generate a new packet with the new ID */ | |
258 | t->sent = dns_packet_unref(t->sent); | |
259 | } | |
260 | ||
261 | static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) { | |
262 | _cleanup_free_ char *pretty = NULL; | |
263 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
264 | DnsZoneItem *z; | |
265 | ||
266 | assert(t); | |
267 | assert(p); | |
268 | ||
269 | if (manager_our_packet(t->scope->manager, p) != 0) | |
270 | return; | |
271 | ||
272 | (void) in_addr_to_string(p->family, &p->sender, &pretty); | |
273 | ||
274 | log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s got tentative packet from %s.", | |
275 | t->id, | |
276 | dns_resource_key_to_string(t->key, key_str, sizeof key_str), | |
277 | dns_protocol_to_string(t->scope->protocol), | |
278 | t->scope->link ? t->scope->link->name : "*", | |
279 | af_to_name_short(t->scope->family), | |
280 | strnull(pretty)); | |
281 | ||
282 | /* RFC 4795, Section 4.1 says that the peer with the | |
283 | * lexicographically smaller IP address loses */ | |
284 | if (memcmp(&p->sender, &p->destination, FAMILY_ADDRESS_SIZE(p->family)) >= 0) { | |
285 | log_debug("Peer has lexicographically larger IP address and thus lost in the conflict."); | |
286 | return; | |
287 | } | |
288 | ||
289 | log_debug("We have the lexicographically larger IP address and thus lost in the conflict."); | |
290 | ||
291 | t->block_gc++; | |
292 | ||
293 | while ((z = set_first(t->notify_zone_items))) { | |
294 | /* First, make sure the zone item drops the reference | |
295 | * to us */ | |
296 | dns_zone_item_probe_stop(z); | |
297 | ||
298 | /* Secondly, report this as conflict, so that we might | |
299 | * look for a different hostname */ | |
300 | dns_zone_item_conflict(z); | |
301 | } | |
302 | t->block_gc--; | |
303 | ||
304 | dns_transaction_gc(t); | |
305 | } | |
306 | ||
307 | void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state) { | |
308 | DnsQueryCandidate *c; | |
309 | DnsZoneItem *z; | |
310 | DnsTransaction *d; | |
311 | const char *st; | |
312 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
313 | ||
314 | assert(t); | |
315 | assert(!DNS_TRANSACTION_IS_LIVE(state)); | |
316 | ||
317 | if (state == DNS_TRANSACTION_DNSSEC_FAILED) { | |
318 | dns_resource_key_to_string(t->key, key_str, sizeof key_str); | |
319 | ||
320 | log_struct(LOG_NOTICE, | |
321 | LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_FAILURE), | |
322 | LOG_MESSAGE("DNSSEC validation failed for question %s: %s", key_str, dnssec_result_to_string(t->answer_dnssec_result)), | |
323 | "DNS_TRANSACTION=%" PRIu16, t->id, | |
324 | "DNS_QUESTION=%s", key_str, | |
325 | "DNSSEC_RESULT=%s", dnssec_result_to_string(t->answer_dnssec_result), | |
326 | "DNS_SERVER=%s", dns_server_string(t->server), | |
327 | "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t->server->possible_feature_level), | |
328 | NULL); | |
329 | } | |
330 | ||
331 | /* Note that this call might invalidate the query. Callers | |
332 | * should hence not attempt to access the query or transaction | |
333 | * after calling this function. */ | |
334 | ||
335 | if (state == DNS_TRANSACTION_ERRNO) | |
336 | st = errno_to_name(t->answer_errno); | |
337 | else | |
338 | st = dns_transaction_state_to_string(state); | |
339 | ||
340 | log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s).", | |
341 | t->id, | |
342 | dns_resource_key_to_string(t->key, key_str, sizeof key_str), | |
343 | dns_protocol_to_string(t->scope->protocol), | |
344 | t->scope->link ? t->scope->link->name : "*", | |
345 | af_to_name_short(t->scope->family), | |
346 | st, | |
347 | t->answer_source < 0 ? "none" : dns_transaction_source_to_string(t->answer_source), | |
348 | t->answer_authenticated ? "authenticated" : "unsigned"); | |
349 | ||
350 | t->state = state; | |
351 | ||
352 | dns_transaction_close_connection(t); | |
353 | dns_transaction_stop_timeout(t); | |
354 | ||
355 | /* Notify all queries that are interested, but make sure the | |
356 | * transaction isn't freed while we are still looking at it */ | |
357 | t->block_gc++; | |
358 | ||
359 | SET_FOREACH_MOVE(c, t->notify_query_candidates_done, t->notify_query_candidates) | |
360 | dns_query_candidate_notify(c); | |
361 | SWAP_TWO(t->notify_query_candidates, t->notify_query_candidates_done); | |
362 | ||
363 | SET_FOREACH_MOVE(z, t->notify_zone_items_done, t->notify_zone_items) | |
364 | dns_zone_item_notify(z); | |
365 | SWAP_TWO(t->notify_zone_items, t->notify_zone_items_done); | |
366 | ||
367 | SET_FOREACH_MOVE(d, t->notify_transactions_done, t->notify_transactions) | |
368 | dns_transaction_notify(d, t); | |
369 | SWAP_TWO(t->notify_transactions, t->notify_transactions_done); | |
370 | ||
371 | t->block_gc--; | |
372 | dns_transaction_gc(t); | |
373 | } | |
374 | ||
375 | static int dns_transaction_pick_server(DnsTransaction *t) { | |
376 | DnsServer *server; | |
377 | ||
378 | assert(t); | |
379 | assert(t->scope->protocol == DNS_PROTOCOL_DNS); | |
380 | ||
381 | server = dns_scope_get_dns_server(t->scope); | |
382 | if (!server) | |
383 | return -ESRCH; | |
384 | ||
385 | t->current_feature_level = dns_server_possible_feature_level(server); | |
386 | ||
387 | if (server == t->server) | |
388 | return 0; | |
389 | ||
390 | dns_server_unref(t->server); | |
391 | t->server = dns_server_ref(server); | |
392 | ||
393 | return 1; | |
394 | } | |
395 | ||
396 | static void dns_transaction_retry(DnsTransaction *t) { | |
397 | int r; | |
398 | ||
399 | assert(t); | |
400 | ||
401 | log_debug("Retrying transaction %" PRIu16 ".", t->id); | |
402 | ||
403 | /* Before we try again, switch to a new server. */ | |
404 | dns_scope_next_dns_server(t->scope); | |
405 | ||
406 | r = dns_transaction_go(t); | |
407 | if (r < 0) { | |
408 | t->answer_errno = -r; | |
409 | dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); | |
410 | } | |
411 | } | |
412 | ||
413 | static int dns_transaction_maybe_restart(DnsTransaction *t) { | |
414 | int r; | |
415 | ||
416 | assert(t); | |
417 | ||
418 | /* Returns > 0 if the transaction was restarted, 0 if not */ | |
419 | ||
420 | if (!t->server) | |
421 | return 0; | |
422 | ||
423 | if (t->current_feature_level <= dns_server_possible_feature_level(t->server)) | |
424 | return 0; | |
425 | ||
426 | /* The server's current feature level is lower than when we sent the original query. We learnt something from | |
427 | the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to | |
428 | restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include | |
429 | OPT RR or DO bit. One of these cases is documented here, for example: | |
430 | https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */ | |
431 | ||
432 | log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID."); | |
433 | dns_transaction_shuffle_id(t); | |
434 | ||
435 | r = dns_transaction_go(t); | |
436 | if (r < 0) | |
437 | return r; | |
438 | ||
439 | return 1; | |
440 | } | |
441 | ||
442 | static int on_stream_complete(DnsStream *s, int error) { | |
443 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
444 | DnsTransaction *t; | |
445 | ||
446 | assert(s); | |
447 | assert(s->transaction); | |
448 | ||
449 | /* Copy the data we care about out of the stream before we | |
450 | * destroy it. */ | |
451 | t = s->transaction; | |
452 | p = dns_packet_ref(s->read_packet); | |
453 | ||
454 | dns_transaction_close_connection(t); | |
455 | ||
456 | if (ERRNO_IS_DISCONNECT(error)) { | |
457 | usec_t usec; | |
458 | ||
459 | if (t->scope->protocol == DNS_PROTOCOL_LLMNR) { | |
460 | /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the | |
461 | * question on this scope. */ | |
462 | dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND); | |
463 | return 0; | |
464 | } | |
465 | ||
466 | log_debug_errno(error, "Connection failure for DNS TCP stream: %m"); | |
467 | assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &usec) >= 0); | |
468 | dns_server_packet_lost(t->server, IPPROTO_TCP, t->current_feature_level, usec - t->start_usec); | |
469 | ||
470 | dns_transaction_retry(t); | |
471 | return 0; | |
472 | } | |
473 | if (error != 0) { | |
474 | t->answer_errno = error; | |
475 | dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); | |
476 | return 0; | |
477 | } | |
478 | ||
479 | if (dns_packet_validate_reply(p) <= 0) { | |
480 | log_debug("Invalid TCP reply packet."); | |
481 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
482 | return 0; | |
483 | } | |
484 | ||
485 | dns_scope_check_conflicts(t->scope, p); | |
486 | ||
487 | t->block_gc++; | |
488 | dns_transaction_process_reply(t, p); | |
489 | t->block_gc--; | |
490 | ||
491 | /* If the response wasn't useful, then complete the transition | |
492 | * now. After all, we are the worst feature set now with TCP | |
493 | * sockets, and there's really no point in retrying. */ | |
494 | if (t->state == DNS_TRANSACTION_PENDING) | |
495 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
496 | else | |
497 | dns_transaction_gc(t); | |
498 | ||
499 | return 0; | |
500 | } | |
501 | ||
502 | static int dns_transaction_open_tcp(DnsTransaction *t) { | |
503 | _cleanup_close_ int fd = -1; | |
504 | int r; | |
505 | ||
506 | assert(t); | |
507 | ||
508 | dns_transaction_close_connection(t); | |
509 | ||
510 | switch (t->scope->protocol) { | |
511 | ||
512 | case DNS_PROTOCOL_DNS: | |
513 | r = dns_transaction_pick_server(t); | |
514 | if (r < 0) | |
515 | return r; | |
516 | ||
517 | if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(t->key->type)) | |
518 | return -EOPNOTSUPP; | |
519 | ||
520 | r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level); | |
521 | if (r < 0) | |
522 | return r; | |
523 | ||
524 | fd = dns_scope_socket_tcp(t->scope, AF_UNSPEC, NULL, t->server, 53); | |
525 | break; | |
526 | ||
527 | case DNS_PROTOCOL_LLMNR: | |
528 | /* When we already received a reply to this (but it was truncated), send to its sender address */ | |
529 | if (t->received) | |
530 | fd = dns_scope_socket_tcp(t->scope, t->received->family, &t->received->sender, NULL, t->received->sender_port); | |
531 | else { | |
532 | union in_addr_union address; | |
533 | int family = AF_UNSPEC; | |
534 | ||
535 | /* Otherwise, try to talk to the owner of a | |
536 | * the IP address, in case this is a reverse | |
537 | * PTR lookup */ | |
538 | ||
539 | r = dns_name_address(dns_resource_key_name(t->key), &family, &address); | |
540 | if (r < 0) | |
541 | return r; | |
542 | if (r == 0) | |
543 | return -EINVAL; | |
544 | if (family != t->scope->family) | |
545 | return -ESRCH; | |
546 | ||
547 | fd = dns_scope_socket_tcp(t->scope, family, &address, NULL, LLMNR_PORT); | |
548 | } | |
549 | ||
550 | break; | |
551 | ||
552 | default: | |
553 | return -EAFNOSUPPORT; | |
554 | } | |
555 | ||
556 | if (fd < 0) | |
557 | return fd; | |
558 | ||
559 | r = dns_stream_new(t->scope->manager, &t->stream, t->scope->protocol, fd); | |
560 | if (r < 0) | |
561 | return r; | |
562 | fd = -1; | |
563 | ||
564 | r = dns_stream_write_packet(t->stream, t->sent); | |
565 | if (r < 0) { | |
566 | t->stream = dns_stream_unref(t->stream); | |
567 | return r; | |
568 | } | |
569 | ||
570 | t->stream->complete = on_stream_complete; | |
571 | t->stream->transaction = t; | |
572 | ||
573 | /* The interface index is difficult to determine if we are | |
574 | * connecting to the local host, hence fill this in right away | |
575 | * instead of determining it from the socket */ | |
576 | t->stream->ifindex = dns_scope_ifindex(t->scope); | |
577 | ||
578 | dns_transaction_reset_answer(t); | |
579 | ||
580 | t->tried_stream = true; | |
581 | ||
582 | return 0; | |
583 | } | |
584 | ||
585 | static void dns_transaction_cache_answer(DnsTransaction *t) { | |
586 | assert(t); | |
587 | ||
588 | /* For mDNS we cache whenever we get the packet, rather than | |
589 | * in each transaction. */ | |
590 | if (!IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR)) | |
591 | return; | |
592 | ||
593 | /* We never cache if this packet is from the local host, under | |
594 | * the assumption that a locally running DNS server would | |
595 | * cache this anyway, and probably knows better when to flush | |
596 | * the cache then we could. */ | |
597 | if (!DNS_PACKET_SHALL_CACHE(t->received)) | |
598 | return; | |
599 | ||
600 | dns_cache_put(&t->scope->cache, | |
601 | t->key, | |
602 | t->answer_rcode, | |
603 | t->answer, | |
604 | t->answer_authenticated, | |
605 | t->answer_nsec_ttl, | |
606 | 0, | |
607 | t->received->family, | |
608 | &t->received->sender); | |
609 | } | |
610 | ||
611 | static bool dns_transaction_dnssec_is_live(DnsTransaction *t) { | |
612 | DnsTransaction *dt; | |
613 | Iterator i; | |
614 | ||
615 | assert(t); | |
616 | ||
617 | SET_FOREACH(dt, t->dnssec_transactions, i) | |
618 | if (DNS_TRANSACTION_IS_LIVE(dt->state)) | |
619 | return true; | |
620 | ||
621 | return false; | |
622 | } | |
623 | ||
624 | static int dns_transaction_dnssec_ready(DnsTransaction *t) { | |
625 | DnsTransaction *dt; | |
626 | Iterator i; | |
627 | ||
628 | assert(t); | |
629 | ||
630 | /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still | |
631 | * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */ | |
632 | ||
633 | SET_FOREACH(dt, t->dnssec_transactions, i) { | |
634 | ||
635 | switch (dt->state) { | |
636 | ||
637 | case DNS_TRANSACTION_NULL: | |
638 | case DNS_TRANSACTION_PENDING: | |
639 | case DNS_TRANSACTION_VALIDATING: | |
640 | /* Still ongoing */ | |
641 | return 0; | |
642 | ||
643 | case DNS_TRANSACTION_RCODE_FAILURE: | |
644 | if (dt->answer_rcode != DNS_RCODE_NXDOMAIN) { | |
645 | log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt->answer_rcode)); | |
646 | goto fail; | |
647 | } | |
648 | ||
649 | /* Fall-through: NXDOMAIN is good enough for us. This is because some DNS servers erronously | |
650 | * return NXDOMAIN for empty non-terminals (Akamai...), and we need to handle that nicely, when | |
651 | * asking for parent SOA or similar RRs to make unsigned proofs. */ | |
652 | ||
653 | case DNS_TRANSACTION_SUCCESS: | |
654 | /* All good. */ | |
655 | break; | |
656 | ||
657 | case DNS_TRANSACTION_DNSSEC_FAILED: | |
658 | /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC | |
659 | * validationr result */ | |
660 | ||
661 | log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt->answer_dnssec_result)); | |
662 | t->answer_dnssec_result = dt->answer_dnssec_result; /* Copy error code over */ | |
663 | dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); | |
664 | return 0; | |
665 | ||
666 | ||
667 | default: | |
668 | log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt->state)); | |
669 | goto fail; | |
670 | } | |
671 | } | |
672 | ||
673 | /* All is ready, we can go and validate */ | |
674 | return 1; | |
675 | ||
676 | fail: | |
677 | t->answer_dnssec_result = DNSSEC_FAILED_AUXILIARY; | |
678 | dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); | |
679 | return 0; | |
680 | } | |
681 | ||
682 | static void dns_transaction_process_dnssec(DnsTransaction *t) { | |
683 | int r; | |
684 | ||
685 | assert(t); | |
686 | ||
687 | /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */ | |
688 | r = dns_transaction_dnssec_ready(t); | |
689 | if (r < 0) | |
690 | goto fail; | |
691 | if (r == 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */ | |
692 | return; | |
693 | ||
694 | /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better | |
695 | * restart the lookup immediately. */ | |
696 | r = dns_transaction_maybe_restart(t); | |
697 | if (r < 0) | |
698 | goto fail; | |
699 | if (r > 0) /* Transaction got restarted... */ | |
700 | return; | |
701 | ||
702 | /* All our auxiliary DNSSEC transactions are complete now. Try | |
703 | * to validate our RRset now. */ | |
704 | r = dns_transaction_validate_dnssec(t); | |
705 | if (r == -EBADMSG) { | |
706 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
707 | return; | |
708 | } | |
709 | if (r < 0) | |
710 | goto fail; | |
711 | ||
712 | if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER && | |
713 | t->scope->dnssec_mode == DNSSEC_YES) { | |
714 | /* We are not in automatic downgrade mode, and the | |
715 | * server is bad, refuse operation. */ | |
716 | dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); | |
717 | return; | |
718 | } | |
719 | ||
720 | if (!IN_SET(t->answer_dnssec_result, | |
721 | _DNSSEC_RESULT_INVALID, /* No DNSSEC validation enabled */ | |
722 | DNSSEC_VALIDATED, /* Answer is signed and validated successfully */ | |
723 | DNSSEC_UNSIGNED, /* Answer is right-fully unsigned */ | |
724 | DNSSEC_INCOMPATIBLE_SERVER)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */ | |
725 | dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); | |
726 | return; | |
727 | } | |
728 | ||
729 | if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER) | |
730 | dns_server_warn_downgrade(t->server); | |
731 | ||
732 | dns_transaction_cache_answer(t); | |
733 | ||
734 | if (t->answer_rcode == DNS_RCODE_SUCCESS) | |
735 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
736 | else | |
737 | dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE); | |
738 | ||
739 | return; | |
740 | ||
741 | fail: | |
742 | t->answer_errno = -r; | |
743 | dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); | |
744 | } | |
745 | ||
746 | static int dns_transaction_has_positive_answer(DnsTransaction *t, DnsAnswerFlags *flags) { | |
747 | int r; | |
748 | ||
749 | assert(t); | |
750 | ||
751 | /* Checks whether the answer is positive, i.e. either a direct | |
752 | * answer to the question, or a CNAME/DNAME for it */ | |
753 | ||
754 | r = dns_answer_match_key(t->answer, t->key, flags); | |
755 | if (r != 0) | |
756 | return r; | |
757 | ||
758 | r = dns_answer_find_cname_or_dname(t->answer, t->key, NULL, flags); | |
759 | if (r != 0) | |
760 | return r; | |
761 | ||
762 | return false; | |
763 | } | |
764 | ||
765 | static int dns_transaction_fix_rcode(DnsTransaction *t) { | |
766 | int r; | |
767 | ||
768 | assert(t); | |
769 | ||
770 | /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the | |
771 | * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a | |
772 | * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first | |
773 | * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when | |
774 | * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle | |
775 | * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a | |
776 | * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server | |
777 | * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an | |
778 | * incomplete CNAME/DNAME chain. | |
779 | * | |
780 | * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS, | |
781 | * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new | |
782 | * lookup. */ | |
783 | ||
784 | if (t->answer_rcode != DNS_RCODE_NXDOMAIN) | |
785 | return 0; | |
786 | ||
787 | r = dns_transaction_has_positive_answer(t, NULL); | |
788 | if (r <= 0) | |
789 | return r; | |
790 | ||
791 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
792 | return 0; | |
793 | } | |
794 | ||
795 | void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) { | |
796 | usec_t ts; | |
797 | int r; | |
798 | ||
799 | assert(t); | |
800 | assert(p); | |
801 | assert(t->scope); | |
802 | assert(t->scope->manager); | |
803 | ||
804 | if (t->state != DNS_TRANSACTION_PENDING) | |
805 | return; | |
806 | ||
807 | /* Note that this call might invalidate the query. Callers | |
808 | * should hence not attempt to access the query or transaction | |
809 | * after calling this function. */ | |
810 | ||
811 | log_debug("Processing incoming packet on transaction %" PRIu16".", t->id); | |
812 | ||
813 | switch (t->scope->protocol) { | |
814 | ||
815 | case DNS_PROTOCOL_LLMNR: | |
816 | /* For LLMNR we will not accept any packets from other interfaces */ | |
817 | ||
818 | if (p->ifindex != dns_scope_ifindex(t->scope)) | |
819 | return; | |
820 | ||
821 | if (p->family != t->scope->family) | |
822 | return; | |
823 | ||
824 | /* Tentative packets are not full responses but still | |
825 | * useful for identifying uniqueness conflicts during | |
826 | * probing. */ | |
827 | if (DNS_PACKET_LLMNR_T(p)) { | |
828 | dns_transaction_tentative(t, p); | |
829 | return; | |
830 | } | |
831 | ||
832 | break; | |
833 | ||
834 | case DNS_PROTOCOL_MDNS: | |
835 | /* For mDNS we will not accept any packets from other interfaces */ | |
836 | ||
837 | if (p->ifindex != dns_scope_ifindex(t->scope)) | |
838 | return; | |
839 | ||
840 | if (p->family != t->scope->family) | |
841 | return; | |
842 | ||
843 | break; | |
844 | ||
845 | case DNS_PROTOCOL_DNS: | |
846 | /* Note that we do not need to verify the | |
847 | * addresses/port numbers of incoming traffic, as we | |
848 | * invoked connect() on our UDP socket in which case | |
849 | * the kernel already does the needed verification for | |
850 | * us. */ | |
851 | break; | |
852 | ||
853 | default: | |
854 | assert_not_reached("Invalid DNS protocol."); | |
855 | } | |
856 | ||
857 | if (t->received != p) { | |
858 | dns_packet_unref(t->received); | |
859 | t->received = dns_packet_ref(p); | |
860 | } | |
861 | ||
862 | t->answer_source = DNS_TRANSACTION_NETWORK; | |
863 | ||
864 | if (p->ipproto == IPPROTO_TCP) { | |
865 | if (DNS_PACKET_TC(p)) { | |
866 | /* Truncated via TCP? Somebody must be fucking with us */ | |
867 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
868 | return; | |
869 | } | |
870 | ||
871 | if (DNS_PACKET_ID(p) != t->id) { | |
872 | /* Not the reply to our query? Somebody must be fucking with us */ | |
873 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
874 | return; | |
875 | } | |
876 | } | |
877 | ||
878 | assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0); | |
879 | ||
880 | switch (t->scope->protocol) { | |
881 | ||
882 | case DNS_PROTOCOL_DNS: | |
883 | assert(t->server); | |
884 | ||
885 | if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_FORMERR, DNS_RCODE_SERVFAIL, DNS_RCODE_NOTIMP)) { | |
886 | ||
887 | /* Request failed, immediately try again with reduced features */ | |
888 | log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p))); | |
889 | ||
890 | dns_server_packet_failed(t->server, t->current_feature_level); | |
891 | dns_transaction_retry(t); | |
892 | return; | |
893 | } else if (DNS_PACKET_TC(p)) | |
894 | dns_server_packet_truncated(t->server, t->current_feature_level); | |
895 | ||
896 | break; | |
897 | ||
898 | case DNS_PROTOCOL_LLMNR: | |
899 | case DNS_PROTOCOL_MDNS: | |
900 | dns_scope_packet_received(t->scope, ts - t->start_usec); | |
901 | break; | |
902 | ||
903 | default: | |
904 | assert_not_reached("Invalid DNS protocol."); | |
905 | } | |
906 | ||
907 | if (DNS_PACKET_TC(p)) { | |
908 | ||
909 | /* Truncated packets for mDNS are not allowed. Give up immediately. */ | |
910 | if (t->scope->protocol == DNS_PROTOCOL_MDNS) { | |
911 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
912 | return; | |
913 | } | |
914 | ||
915 | log_debug("Reply truncated, retrying via TCP."); | |
916 | ||
917 | /* Response was truncated, let's try again with good old TCP */ | |
918 | r = dns_transaction_open_tcp(t); | |
919 | if (r == -ESRCH) { | |
920 | /* No servers found? Damn! */ | |
921 | dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS); | |
922 | return; | |
923 | } | |
924 | if (r == -EOPNOTSUPP) { | |
925 | /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */ | |
926 | dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED); | |
927 | return; | |
928 | } | |
929 | if (r < 0) { | |
930 | /* On LLMNR, if we cannot connect to the host, | |
931 | * we immediately give up */ | |
932 | if (t->scope->protocol != DNS_PROTOCOL_DNS) | |
933 | goto fail; | |
934 | ||
935 | /* On DNS, couldn't send? Try immediately again, with a new server */ | |
936 | dns_transaction_retry(t); | |
937 | } | |
938 | ||
939 | return; | |
940 | } | |
941 | ||
942 | /* After the superficial checks, actually parse the message. */ | |
943 | r = dns_packet_extract(p); | |
944 | if (r < 0) { | |
945 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
946 | return; | |
947 | } | |
948 | ||
949 | /* Report that the OPT RR was missing */ | |
950 | if (t->server) { | |
951 | if (!p->opt) | |
952 | dns_server_packet_bad_opt(t->server, t->current_feature_level); | |
953 | ||
954 | dns_server_packet_received(t->server, p->ipproto, t->current_feature_level, ts - t->start_usec, p->size); | |
955 | } | |
956 | ||
957 | /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */ | |
958 | r = dns_transaction_maybe_restart(t); | |
959 | if (r < 0) | |
960 | goto fail; | |
961 | if (r > 0) /* Transaction got restarted... */ | |
962 | return; | |
963 | ||
964 | if (IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR)) { | |
965 | ||
966 | /* Only consider responses with equivalent query section to the request */ | |
967 | r = dns_packet_is_reply_for(p, t->key); | |
968 | if (r < 0) | |
969 | goto fail; | |
970 | if (r == 0) { | |
971 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
972 | return; | |
973 | } | |
974 | ||
975 | /* Install the answer as answer to the transaction */ | |
976 | dns_answer_unref(t->answer); | |
977 | t->answer = dns_answer_ref(p->answer); | |
978 | t->answer_rcode = DNS_PACKET_RCODE(p); | |
979 | t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; | |
980 | t->answer_authenticated = false; | |
981 | ||
982 | r = dns_transaction_fix_rcode(t); | |
983 | if (r < 0) | |
984 | goto fail; | |
985 | ||
986 | /* Block GC while starting requests for additional DNSSEC RRs */ | |
987 | t->block_gc++; | |
988 | r = dns_transaction_request_dnssec_keys(t); | |
989 | t->block_gc--; | |
990 | ||
991 | /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */ | |
992 | if (!dns_transaction_gc(t)) | |
993 | return; | |
994 | ||
995 | /* Requesting additional keys might have resulted in | |
996 | * this transaction to fail, since the auxiliary | |
997 | * request failed for some reason. If so, we are not | |
998 | * in pending state anymore, and we should exit | |
999 | * quickly. */ | |
1000 | if (t->state != DNS_TRANSACTION_PENDING) | |
1001 | return; | |
1002 | if (r < 0) | |
1003 | goto fail; | |
1004 | if (r > 0) { | |
1005 | /* There are DNSSEC transactions pending now. Update the state accordingly. */ | |
1006 | t->state = DNS_TRANSACTION_VALIDATING; | |
1007 | dns_transaction_close_connection(t); | |
1008 | dns_transaction_stop_timeout(t); | |
1009 | return; | |
1010 | } | |
1011 | } | |
1012 | ||
1013 | dns_transaction_process_dnssec(t); | |
1014 | return; | |
1015 | ||
1016 | fail: | |
1017 | t->answer_errno = -r; | |
1018 | dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); | |
1019 | } | |
1020 | ||
1021 | static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { | |
1022 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
1023 | DnsTransaction *t = userdata; | |
1024 | int r; | |
1025 | ||
1026 | assert(t); | |
1027 | assert(t->scope); | |
1028 | ||
1029 | r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p); | |
1030 | if (ERRNO_IS_DISCONNECT(-r)) { | |
1031 | usec_t usec; | |
1032 | ||
1033 | /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next | |
1034 | * recvmsg(). Treat this like a lost packet. */ | |
1035 | ||
1036 | log_debug_errno(r, "Connection failure for DNS UDP packet: %m"); | |
1037 | assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &usec) >= 0); | |
1038 | dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level, usec - t->start_usec); | |
1039 | ||
1040 | dns_transaction_retry(t); | |
1041 | return 0; | |
1042 | } | |
1043 | if (r < 0) { | |
1044 | dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); | |
1045 | t->answer_errno = -r; | |
1046 | return 0; | |
1047 | } | |
1048 | ||
1049 | r = dns_packet_validate_reply(p); | |
1050 | if (r < 0) { | |
1051 | log_debug_errno(r, "Received invalid DNS packet as response, ignoring: %m"); | |
1052 | return 0; | |
1053 | } | |
1054 | if (r == 0) { | |
1055 | log_debug("Received inappropriate DNS packet as response, ignoring."); | |
1056 | return 0; | |
1057 | } | |
1058 | ||
1059 | if (DNS_PACKET_ID(p) != t->id) { | |
1060 | log_debug("Received packet with incorrect transaction ID, ignoring."); | |
1061 | return 0; | |
1062 | } | |
1063 | ||
1064 | dns_transaction_process_reply(t, p); | |
1065 | return 0; | |
1066 | } | |
1067 | ||
1068 | static int dns_transaction_emit_udp(DnsTransaction *t) { | |
1069 | int r; | |
1070 | ||
1071 | assert(t); | |
1072 | ||
1073 | if (t->scope->protocol == DNS_PROTOCOL_DNS) { | |
1074 | ||
1075 | r = dns_transaction_pick_server(t); | |
1076 | if (r < 0) | |
1077 | return r; | |
1078 | ||
1079 | if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_UDP) | |
1080 | return -EAGAIN; | |
1081 | ||
1082 | if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(t->key->type)) | |
1083 | return -EOPNOTSUPP; | |
1084 | ||
1085 | if (r > 0 || t->dns_udp_fd < 0) { /* Server changed, or no connection yet. */ | |
1086 | int fd; | |
1087 | ||
1088 | dns_transaction_close_connection(t); | |
1089 | ||
1090 | fd = dns_scope_socket_udp(t->scope, t->server, 53); | |
1091 | if (fd < 0) | |
1092 | return fd; | |
1093 | ||
1094 | r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t); | |
1095 | if (r < 0) { | |
1096 | safe_close(fd); | |
1097 | return r; | |
1098 | } | |
1099 | ||
1100 | (void) sd_event_source_set_description(t->dns_udp_event_source, "dns-transaction-udp"); | |
1101 | t->dns_udp_fd = fd; | |
1102 | } | |
1103 | ||
1104 | r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level); | |
1105 | if (r < 0) | |
1106 | return r; | |
1107 | } else | |
1108 | dns_transaction_close_connection(t); | |
1109 | ||
1110 | r = dns_scope_emit_udp(t->scope, t->dns_udp_fd, t->sent); | |
1111 | if (r < 0) | |
1112 | return r; | |
1113 | ||
1114 | dns_transaction_reset_answer(t); | |
1115 | ||
1116 | return 0; | |
1117 | } | |
1118 | ||
1119 | static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) { | |
1120 | DnsTransaction *t = userdata; | |
1121 | ||
1122 | assert(s); | |
1123 | assert(t); | |
1124 | ||
1125 | if (!t->initial_jitter_scheduled || t->initial_jitter_elapsed) { | |
1126 | /* Timeout reached? Increase the timeout for the server used */ | |
1127 | switch (t->scope->protocol) { | |
1128 | ||
1129 | case DNS_PROTOCOL_DNS: | |
1130 | assert(t->server); | |
1131 | dns_server_packet_lost(t->server, t->stream ? IPPROTO_TCP : IPPROTO_UDP, t->current_feature_level, usec - t->start_usec); | |
1132 | break; | |
1133 | ||
1134 | case DNS_PROTOCOL_LLMNR: | |
1135 | case DNS_PROTOCOL_MDNS: | |
1136 | dns_scope_packet_lost(t->scope, usec - t->start_usec); | |
1137 | break; | |
1138 | ||
1139 | default: | |
1140 | assert_not_reached("Invalid DNS protocol."); | |
1141 | } | |
1142 | ||
1143 | if (t->initial_jitter_scheduled) | |
1144 | t->initial_jitter_elapsed = true; | |
1145 | } | |
1146 | ||
1147 | log_debug("Timeout reached on transaction %" PRIu16 ".", t->id); | |
1148 | ||
1149 | dns_transaction_retry(t); | |
1150 | return 0; | |
1151 | } | |
1152 | ||
1153 | static usec_t transaction_get_resend_timeout(DnsTransaction *t) { | |
1154 | assert(t); | |
1155 | assert(t->scope); | |
1156 | ||
1157 | switch (t->scope->protocol) { | |
1158 | ||
1159 | case DNS_PROTOCOL_DNS: | |
1160 | assert(t->server); | |
1161 | return t->server->resend_timeout; | |
1162 | ||
1163 | case DNS_PROTOCOL_MDNS: | |
1164 | assert(t->n_attempts > 0); | |
1165 | return (1 << (t->n_attempts - 1)) * USEC_PER_SEC; | |
1166 | ||
1167 | case DNS_PROTOCOL_LLMNR: | |
1168 | return t->scope->resend_timeout; | |
1169 | ||
1170 | default: | |
1171 | assert_not_reached("Invalid DNS protocol."); | |
1172 | } | |
1173 | } | |
1174 | ||
1175 | static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) { | |
1176 | int r; | |
1177 | ||
1178 | assert(t); | |
1179 | ||
1180 | dns_transaction_stop_timeout(t); | |
1181 | ||
1182 | r = dns_scope_network_good(t->scope); | |
1183 | if (r < 0) | |
1184 | return r; | |
1185 | if (r == 0) { | |
1186 | dns_transaction_complete(t, DNS_TRANSACTION_NETWORK_DOWN); | |
1187 | return 0; | |
1188 | } | |
1189 | ||
1190 | if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) { | |
1191 | dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED); | |
1192 | return 0; | |
1193 | } | |
1194 | ||
1195 | if (t->scope->protocol == DNS_PROTOCOL_LLMNR && t->tried_stream) { | |
1196 | /* If we already tried via a stream, then we don't | |
1197 | * retry on LLMNR. See RFC 4795, Section 2.7. */ | |
1198 | dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED); | |
1199 | return 0; | |
1200 | } | |
1201 | ||
1202 | t->n_attempts++; | |
1203 | t->start_usec = ts; | |
1204 | ||
1205 | dns_transaction_reset_answer(t); | |
1206 | dns_transaction_flush_dnssec_transactions(t); | |
1207 | ||
1208 | /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */ | |
1209 | if (t->scope->protocol == DNS_PROTOCOL_DNS) { | |
1210 | r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, t->key, &t->answer); | |
1211 | if (r < 0) | |
1212 | return r; | |
1213 | if (r > 0) { | |
1214 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
1215 | t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR; | |
1216 | t->answer_authenticated = true; | |
1217 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
1218 | return 0; | |
1219 | } | |
1220 | ||
1221 | if (dns_name_is_root(dns_resource_key_name(t->key)) && | |
1222 | t->key->type == DNS_TYPE_DS) { | |
1223 | ||
1224 | /* Hmm, this is a request for the root DS? A | |
1225 | * DS RR doesn't exist in the root zone, and | |
1226 | * if our trust anchor didn't know it either, | |
1227 | * this means we cannot do any DNSSEC logic | |
1228 | * anymore. */ | |
1229 | ||
1230 | if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) { | |
1231 | /* We are in downgrade mode. In this | |
1232 | * case, synthesize an unsigned empty | |
1233 | * response, so that the any lookup | |
1234 | * depending on this one can continue | |
1235 | * assuming there was no DS, and hence | |
1236 | * the root zone was unsigned. */ | |
1237 | ||
1238 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
1239 | t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR; | |
1240 | t->answer_authenticated = false; | |
1241 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
1242 | } else | |
1243 | /* If we are not in downgrade mode, | |
1244 | * then fail the lookup, because we | |
1245 | * cannot reasonably answer it. There | |
1246 | * might be DS RRs, but we don't know | |
1247 | * them, and the DNS server won't tell | |
1248 | * them to us (and even if it would, | |
1249 | * we couldn't validate and trust them. */ | |
1250 | dns_transaction_complete(t, DNS_TRANSACTION_NO_TRUST_ANCHOR); | |
1251 | ||
1252 | return 0; | |
1253 | } | |
1254 | } | |
1255 | ||
1256 | /* Check the zone, but only if this transaction is not used | |
1257 | * for probing or verifying a zone item. */ | |
1258 | if (set_isempty(t->notify_zone_items)) { | |
1259 | ||
1260 | r = dns_zone_lookup(&t->scope->zone, t->key, dns_scope_ifindex(t->scope), &t->answer, NULL, NULL); | |
1261 | if (r < 0) | |
1262 | return r; | |
1263 | if (r > 0) { | |
1264 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
1265 | t->answer_source = DNS_TRANSACTION_ZONE; | |
1266 | t->answer_authenticated = true; | |
1267 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
1268 | return 0; | |
1269 | } | |
1270 | } | |
1271 | ||
1272 | /* Check the cache, but only if this transaction is not used | |
1273 | * for probing or verifying a zone item. */ | |
1274 | if (set_isempty(t->notify_zone_items)) { | |
1275 | ||
1276 | /* Before trying the cache, let's make sure we figured out a | |
1277 | * server to use. Should this cause a change of server this | |
1278 | * might flush the cache. */ | |
1279 | dns_scope_get_dns_server(t->scope); | |
1280 | ||
1281 | /* Let's then prune all outdated entries */ | |
1282 | dns_cache_prune(&t->scope->cache); | |
1283 | ||
1284 | r = dns_cache_lookup(&t->scope->cache, t->key, t->clamp_ttl, &t->answer_rcode, &t->answer, &t->answer_authenticated); | |
1285 | if (r < 0) | |
1286 | return r; | |
1287 | if (r > 0) { | |
1288 | t->answer_source = DNS_TRANSACTION_CACHE; | |
1289 | if (t->answer_rcode == DNS_RCODE_SUCCESS) | |
1290 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
1291 | else | |
1292 | dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE); | |
1293 | return 0; | |
1294 | } | |
1295 | } | |
1296 | ||
1297 | return 1; | |
1298 | } | |
1299 | ||
1300 | static int dns_transaction_make_packet_mdns(DnsTransaction *t) { | |
1301 | ||
1302 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
1303 | bool add_known_answers = false; | |
1304 | DnsTransaction *other; | |
1305 | unsigned qdcount; | |
1306 | usec_t ts; | |
1307 | int r; | |
1308 | ||
1309 | assert(t); | |
1310 | assert(t->scope->protocol == DNS_PROTOCOL_MDNS); | |
1311 | ||
1312 | /* Discard any previously prepared packet, so we can start over and coalesce again */ | |
1313 | t->sent = dns_packet_unref(t->sent); | |
1314 | ||
1315 | r = dns_packet_new_query(&p, t->scope->protocol, 0, false); | |
1316 | if (r < 0) | |
1317 | return r; | |
1318 | ||
1319 | r = dns_packet_append_key(p, t->key, NULL); | |
1320 | if (r < 0) | |
1321 | return r; | |
1322 | ||
1323 | qdcount = 1; | |
1324 | ||
1325 | if (dns_key_is_shared(t->key)) | |
1326 | add_known_answers = true; | |
1327 | ||
1328 | /* | |
1329 | * For mDNS, we want to coalesce as many open queries in pending transactions into one single | |
1330 | * query packet on the wire as possible. To achieve that, we iterate through all pending transactions | |
1331 | * in our current scope, and see whether their timing contraints allow them to be sent. | |
1332 | */ | |
1333 | ||
1334 | assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0); | |
1335 | ||
1336 | LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) { | |
1337 | ||
1338 | /* Skip ourselves */ | |
1339 | if (other == t) | |
1340 | continue; | |
1341 | ||
1342 | if (other->state != DNS_TRANSACTION_PENDING) | |
1343 | continue; | |
1344 | ||
1345 | if (other->next_attempt_after > ts) | |
1346 | continue; | |
1347 | ||
1348 | if (qdcount >= UINT16_MAX) | |
1349 | break; | |
1350 | ||
1351 | r = dns_packet_append_key(p, other->key, NULL); | |
1352 | ||
1353 | /* | |
1354 | * If we can't stuff more questions into the packet, just give up. | |
1355 | * One of the 'other' transactions will fire later and take care of the rest. | |
1356 | */ | |
1357 | if (r == -EMSGSIZE) | |
1358 | break; | |
1359 | ||
1360 | if (r < 0) | |
1361 | return r; | |
1362 | ||
1363 | r = dns_transaction_prepare(other, ts); | |
1364 | if (r <= 0) | |
1365 | continue; | |
1366 | ||
1367 | ts += transaction_get_resend_timeout(other); | |
1368 | ||
1369 | r = sd_event_add_time( | |
1370 | other->scope->manager->event, | |
1371 | &other->timeout_event_source, | |
1372 | clock_boottime_or_monotonic(), | |
1373 | ts, 0, | |
1374 | on_transaction_timeout, other); | |
1375 | if (r < 0) | |
1376 | return r; | |
1377 | ||
1378 | (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout"); | |
1379 | ||
1380 | other->state = DNS_TRANSACTION_PENDING; | |
1381 | other->next_attempt_after = ts; | |
1382 | ||
1383 | qdcount++; | |
1384 | ||
1385 | if (dns_key_is_shared(other->key)) | |
1386 | add_known_answers = true; | |
1387 | } | |
1388 | ||
1389 | DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount); | |
1390 | ||
1391 | /* Append known answer section if we're asking for any shared record */ | |
1392 | if (add_known_answers) { | |
1393 | r = dns_cache_export_shared_to_packet(&t->scope->cache, p); | |
1394 | if (r < 0) | |
1395 | return r; | |
1396 | } | |
1397 | ||
1398 | t->sent = p; | |
1399 | p = NULL; | |
1400 | ||
1401 | return 0; | |
1402 | } | |
1403 | ||
1404 | static int dns_transaction_make_packet(DnsTransaction *t) { | |
1405 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
1406 | int r; | |
1407 | ||
1408 | assert(t); | |
1409 | ||
1410 | if (t->scope->protocol == DNS_PROTOCOL_MDNS) | |
1411 | return dns_transaction_make_packet_mdns(t); | |
1412 | ||
1413 | if (t->sent) | |
1414 | return 0; | |
1415 | ||
1416 | r = dns_packet_new_query(&p, t->scope->protocol, 0, t->scope->dnssec_mode != DNSSEC_NO); | |
1417 | if (r < 0) | |
1418 | return r; | |
1419 | ||
1420 | r = dns_packet_append_key(p, t->key, NULL); | |
1421 | if (r < 0) | |
1422 | return r; | |
1423 | ||
1424 | DNS_PACKET_HEADER(p)->qdcount = htobe16(1); | |
1425 | DNS_PACKET_HEADER(p)->id = t->id; | |
1426 | ||
1427 | t->sent = p; | |
1428 | p = NULL; | |
1429 | ||
1430 | return 0; | |
1431 | } | |
1432 | ||
1433 | int dns_transaction_go(DnsTransaction *t) { | |
1434 | usec_t ts; | |
1435 | int r; | |
1436 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
1437 | ||
1438 | assert(t); | |
1439 | ||
1440 | /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has finished | |
1441 | * now. */ | |
1442 | ||
1443 | assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0); | |
1444 | ||
1445 | r = dns_transaction_prepare(t, ts); | |
1446 | if (r <= 0) | |
1447 | return r; | |
1448 | ||
1449 | log_debug("Transaction %" PRIu16 " for <%s> scope %s on %s/%s.", | |
1450 | t->id, | |
1451 | dns_resource_key_to_string(t->key, key_str, sizeof key_str), | |
1452 | dns_protocol_to_string(t->scope->protocol), | |
1453 | t->scope->link ? t->scope->link->name : "*", | |
1454 | af_to_name_short(t->scope->family)); | |
1455 | ||
1456 | if (!t->initial_jitter_scheduled && | |
1457 | (t->scope->protocol == DNS_PROTOCOL_LLMNR || | |
1458 | t->scope->protocol == DNS_PROTOCOL_MDNS)) { | |
1459 | usec_t jitter, accuracy; | |
1460 | ||
1461 | /* RFC 4795 Section 2.7 suggests all queries should be | |
1462 | * delayed by a random time from 0 to JITTER_INTERVAL. */ | |
1463 | ||
1464 | t->initial_jitter_scheduled = true; | |
1465 | ||
1466 | random_bytes(&jitter, sizeof(jitter)); | |
1467 | ||
1468 | switch (t->scope->protocol) { | |
1469 | ||
1470 | case DNS_PROTOCOL_LLMNR: | |
1471 | jitter %= LLMNR_JITTER_INTERVAL_USEC; | |
1472 | accuracy = LLMNR_JITTER_INTERVAL_USEC; | |
1473 | break; | |
1474 | ||
1475 | case DNS_PROTOCOL_MDNS: | |
1476 | jitter %= MDNS_JITTER_RANGE_USEC; | |
1477 | jitter += MDNS_JITTER_MIN_USEC; | |
1478 | accuracy = MDNS_JITTER_RANGE_USEC; | |
1479 | break; | |
1480 | default: | |
1481 | assert_not_reached("bad protocol"); | |
1482 | } | |
1483 | ||
1484 | r = sd_event_add_time( | |
1485 | t->scope->manager->event, | |
1486 | &t->timeout_event_source, | |
1487 | clock_boottime_or_monotonic(), | |
1488 | ts + jitter, accuracy, | |
1489 | on_transaction_timeout, t); | |
1490 | if (r < 0) | |
1491 | return r; | |
1492 | ||
1493 | (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout"); | |
1494 | ||
1495 | t->n_attempts = 0; | |
1496 | t->next_attempt_after = ts; | |
1497 | t->state = DNS_TRANSACTION_PENDING; | |
1498 | ||
1499 | log_debug("Delaying %s transaction for " USEC_FMT "us.", dns_protocol_to_string(t->scope->protocol), jitter); | |
1500 | return 0; | |
1501 | } | |
1502 | ||
1503 | /* Otherwise, we need to ask the network */ | |
1504 | r = dns_transaction_make_packet(t); | |
1505 | if (r < 0) | |
1506 | return r; | |
1507 | ||
1508 | if (t->scope->protocol == DNS_PROTOCOL_LLMNR && | |
1509 | (dns_name_endswith(dns_resource_key_name(t->key), "in-addr.arpa") > 0 || | |
1510 | dns_name_endswith(dns_resource_key_name(t->key), "ip6.arpa") > 0)) { | |
1511 | ||
1512 | /* RFC 4795, Section 2.4. says reverse lookups shall | |
1513 | * always be made via TCP on LLMNR */ | |
1514 | r = dns_transaction_open_tcp(t); | |
1515 | } else { | |
1516 | /* Try via UDP, and if that fails due to large size or lack of | |
1517 | * support try via TCP */ | |
1518 | r = dns_transaction_emit_udp(t); | |
1519 | if (r == -EMSGSIZE) | |
1520 | log_debug("Sending query via TCP since it is too large."); | |
1521 | if (r == -EAGAIN) | |
1522 | log_debug("Sending query via TCP since server doesn't support UDP."); | |
1523 | if (r == -EMSGSIZE || r == -EAGAIN) | |
1524 | r = dns_transaction_open_tcp(t); | |
1525 | } | |
1526 | ||
1527 | if (r == -ESRCH) { | |
1528 | /* No servers to send this to? */ | |
1529 | dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS); | |
1530 | return 0; | |
1531 | } | |
1532 | if (r == -EOPNOTSUPP) { | |
1533 | /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */ | |
1534 | dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED); | |
1535 | return 0; | |
1536 | } | |
1537 | if (t->scope->protocol == DNS_PROTOCOL_LLMNR && ERRNO_IS_DISCONNECT(-r)) { | |
1538 | /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot | |
1539 | * answer this request with this protocol. */ | |
1540 | dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND); | |
1541 | return 0; | |
1542 | } | |
1543 | if (r < 0) { | |
1544 | if (t->scope->protocol != DNS_PROTOCOL_DNS) | |
1545 | return r; | |
1546 | ||
1547 | /* Couldn't send? Try immediately again, with a new server */ | |
1548 | dns_scope_next_dns_server(t->scope); | |
1549 | ||
1550 | return dns_transaction_go(t); | |
1551 | } | |
1552 | ||
1553 | ts += transaction_get_resend_timeout(t); | |
1554 | ||
1555 | r = sd_event_add_time( | |
1556 | t->scope->manager->event, | |
1557 | &t->timeout_event_source, | |
1558 | clock_boottime_or_monotonic(), | |
1559 | ts, 0, | |
1560 | on_transaction_timeout, t); | |
1561 | if (r < 0) | |
1562 | return r; | |
1563 | ||
1564 | (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout"); | |
1565 | ||
1566 | t->state = DNS_TRANSACTION_PENDING; | |
1567 | t->next_attempt_after = ts; | |
1568 | ||
1569 | return 1; | |
1570 | } | |
1571 | ||
1572 | static int dns_transaction_find_cyclic(DnsTransaction *t, DnsTransaction *aux) { | |
1573 | DnsTransaction *n; | |
1574 | Iterator i; | |
1575 | int r; | |
1576 | ||
1577 | assert(t); | |
1578 | assert(aux); | |
1579 | ||
1580 | /* Try to find cyclic dependencies between transaction objects */ | |
1581 | ||
1582 | if (t == aux) | |
1583 | return 1; | |
1584 | ||
1585 | SET_FOREACH(n, aux->dnssec_transactions, i) { | |
1586 | r = dns_transaction_find_cyclic(t, n); | |
1587 | if (r != 0) | |
1588 | return r; | |
1589 | } | |
1590 | ||
1591 | return 0; | |
1592 | } | |
1593 | ||
1594 | static int dns_transaction_add_dnssec_transaction(DnsTransaction *t, DnsResourceKey *key, DnsTransaction **ret) { | |
1595 | DnsTransaction *aux; | |
1596 | int r; | |
1597 | ||
1598 | assert(t); | |
1599 | assert(ret); | |
1600 | assert(key); | |
1601 | ||
1602 | aux = dns_scope_find_transaction(t->scope, key, true); | |
1603 | if (!aux) { | |
1604 | r = dns_transaction_new(&aux, t->scope, key); | |
1605 | if (r < 0) | |
1606 | return r; | |
1607 | } else { | |
1608 | if (set_contains(t->dnssec_transactions, aux)) { | |
1609 | *ret = aux; | |
1610 | return 0; | |
1611 | } | |
1612 | ||
1613 | r = dns_transaction_find_cyclic(t, aux); | |
1614 | if (r < 0) | |
1615 | return r; | |
1616 | if (r > 0) { | |
1617 | char s[DNS_RESOURCE_KEY_STRING_MAX], saux[DNS_RESOURCE_KEY_STRING_MAX]; | |
1618 | ||
1619 | log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16 " (%s) as dependency for %" PRIu16 " (%s).", | |
1620 | aux->id, | |
1621 | dns_resource_key_to_string(t->key, s, sizeof s), | |
1622 | t->id, | |
1623 | dns_resource_key_to_string(aux->key, saux, sizeof saux)); | |
1624 | ||
1625 | return -ELOOP; | |
1626 | } | |
1627 | } | |
1628 | ||
1629 | r = set_ensure_allocated(&t->dnssec_transactions, NULL); | |
1630 | if (r < 0) | |
1631 | goto gc; | |
1632 | ||
1633 | r = set_ensure_allocated(&aux->notify_transactions, NULL); | |
1634 | if (r < 0) | |
1635 | goto gc; | |
1636 | ||
1637 | r = set_ensure_allocated(&aux->notify_transactions_done, NULL); | |
1638 | if (r < 0) | |
1639 | goto gc; | |
1640 | ||
1641 | r = set_put(t->dnssec_transactions, aux); | |
1642 | if (r < 0) | |
1643 | goto gc; | |
1644 | ||
1645 | r = set_put(aux->notify_transactions, t); | |
1646 | if (r < 0) { | |
1647 | (void) set_remove(t->dnssec_transactions, aux); | |
1648 | goto gc; | |
1649 | } | |
1650 | ||
1651 | *ret = aux; | |
1652 | return 1; | |
1653 | ||
1654 | gc: | |
1655 | dns_transaction_gc(aux); | |
1656 | return r; | |
1657 | } | |
1658 | ||
1659 | static int dns_transaction_request_dnssec_rr(DnsTransaction *t, DnsResourceKey *key) { | |
1660 | _cleanup_(dns_answer_unrefp) DnsAnswer *a = NULL; | |
1661 | DnsTransaction *aux; | |
1662 | int r; | |
1663 | ||
1664 | assert(t); | |
1665 | assert(key); | |
1666 | ||
1667 | /* Try to get the data from the trust anchor */ | |
1668 | r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, key, &a); | |
1669 | if (r < 0) | |
1670 | return r; | |
1671 | if (r > 0) { | |
1672 | r = dns_answer_extend(&t->validated_keys, a); | |
1673 | if (r < 0) | |
1674 | return r; | |
1675 | ||
1676 | return 0; | |
1677 | } | |
1678 | ||
1679 | /* This didn't work, ask for it via the network/cache then. */ | |
1680 | r = dns_transaction_add_dnssec_transaction(t, key, &aux); | |
1681 | if (r == -ELOOP) /* This would result in a cyclic dependency */ | |
1682 | return 0; | |
1683 | if (r < 0) | |
1684 | return r; | |
1685 | ||
1686 | if (aux->state == DNS_TRANSACTION_NULL) { | |
1687 | r = dns_transaction_go(aux); | |
1688 | if (r < 0) | |
1689 | return r; | |
1690 | } | |
1691 | ||
1692 | return 1; | |
1693 | } | |
1694 | ||
1695 | static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction *t, const char *name) { | |
1696 | int r; | |
1697 | ||
1698 | assert(t); | |
1699 | ||
1700 | /* Check whether the specified name is in the NTA | |
1701 | * database, either in the global one, or the link-local | |
1702 | * one. */ | |
1703 | ||
1704 | r = dns_trust_anchor_lookup_negative(&t->scope->manager->trust_anchor, name); | |
1705 | if (r != 0) | |
1706 | return r; | |
1707 | ||
1708 | if (!t->scope->link) | |
1709 | return 0; | |
1710 | ||
1711 | return set_contains(t->scope->link->dnssec_negative_trust_anchors, name); | |
1712 | } | |
1713 | ||
1714 | static int dns_transaction_has_unsigned_negative_answer(DnsTransaction *t) { | |
1715 | int r; | |
1716 | ||
1717 | assert(t); | |
1718 | ||
1719 | /* Checks whether the answer is negative, and lacks NSEC/NSEC3 | |
1720 | * RRs to prove it */ | |
1721 | ||
1722 | r = dns_transaction_has_positive_answer(t, NULL); | |
1723 | if (r < 0) | |
1724 | return r; | |
1725 | if (r > 0) | |
1726 | return false; | |
1727 | ||
1728 | /* Is this key explicitly listed as a negative trust anchor? | |
1729 | * If so, it's nothing we need to care about */ | |
1730 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(t->key)); | |
1731 | if (r < 0) | |
1732 | return r; | |
1733 | if (r > 0) | |
1734 | return false; | |
1735 | ||
1736 | /* The answer does not contain any RRs that match to the | |
1737 | * question. If so, let's see if there are any NSEC/NSEC3 RRs | |
1738 | * included. If not, the answer is unsigned. */ | |
1739 | ||
1740 | r = dns_answer_contains_nsec_or_nsec3(t->answer); | |
1741 | if (r < 0) | |
1742 | return r; | |
1743 | if (r > 0) | |
1744 | return false; | |
1745 | ||
1746 | return true; | |
1747 | } | |
1748 | ||
1749 | static int dns_transaction_is_primary_response(DnsTransaction *t, DnsResourceRecord *rr) { | |
1750 | int r; | |
1751 | ||
1752 | assert(t); | |
1753 | assert(rr); | |
1754 | ||
1755 | /* Check if the specified RR is the "primary" response, | |
1756 | * i.e. either matches the question precisely or is a | |
1757 | * CNAME/DNAME for it. */ | |
1758 | ||
1759 | r = dns_resource_key_match_rr(t->key, rr, NULL); | |
1760 | if (r != 0) | |
1761 | return r; | |
1762 | ||
1763 | return dns_resource_key_match_cname_or_dname(t->key, rr->key, NULL); | |
1764 | } | |
1765 | ||
1766 | static bool dns_transaction_dnssec_supported(DnsTransaction *t) { | |
1767 | assert(t); | |
1768 | ||
1769 | /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon | |
1770 | * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */ | |
1771 | ||
1772 | if (t->scope->protocol != DNS_PROTOCOL_DNS) | |
1773 | return false; | |
1774 | ||
1775 | /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well | |
1776 | * be supported, hence return true. */ | |
1777 | if (!t->server) | |
1778 | return true; | |
1779 | ||
1780 | if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_DO) | |
1781 | return false; | |
1782 | ||
1783 | return dns_server_dnssec_supported(t->server); | |
1784 | } | |
1785 | ||
1786 | static bool dns_transaction_dnssec_supported_full(DnsTransaction *t) { | |
1787 | DnsTransaction *dt; | |
1788 | Iterator i; | |
1789 | ||
1790 | assert(t); | |
1791 | ||
1792 | /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */ | |
1793 | ||
1794 | if (!dns_transaction_dnssec_supported(t)) | |
1795 | return false; | |
1796 | ||
1797 | SET_FOREACH(dt, t->dnssec_transactions, i) | |
1798 | if (!dns_transaction_dnssec_supported(dt)) | |
1799 | return false; | |
1800 | ||
1801 | return true; | |
1802 | } | |
1803 | ||
1804 | int dns_transaction_request_dnssec_keys(DnsTransaction *t) { | |
1805 | DnsResourceRecord *rr; | |
1806 | ||
1807 | int r; | |
1808 | ||
1809 | assert(t); | |
1810 | ||
1811 | /* | |
1812 | * Retrieve all auxiliary RRs for the answer we got, so that | |
1813 | * we can verify signatures or prove that RRs are rightfully | |
1814 | * unsigned. Specifically: | |
1815 | * | |
1816 | * - For RRSIG we get the matching DNSKEY | |
1817 | * - For DNSKEY we get the matching DS | |
1818 | * - For unsigned SOA/NS we get the matching DS | |
1819 | * - For unsigned CNAME/DNAME/DS we get the parent SOA RR | |
1820 | * - For other unsigned RRs we get the matching SOA RR | |
1821 | * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR | |
1822 | * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR | |
1823 | * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR | |
1824 | */ | |
1825 | ||
1826 | if (t->scope->dnssec_mode == DNSSEC_NO) | |
1827 | return 0; | |
1828 | if (t->answer_source != DNS_TRANSACTION_NETWORK) | |
1829 | return 0; /* We only need to validate stuff from the network */ | |
1830 | if (!dns_transaction_dnssec_supported(t)) | |
1831 | return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */ | |
1832 | ||
1833 | DNS_ANSWER_FOREACH(rr, t->answer) { | |
1834 | ||
1835 | if (dns_type_is_pseudo(rr->key->type)) | |
1836 | continue; | |
1837 | ||
1838 | /* If this RR is in the negative trust anchor, we don't need to validate it. */ | |
1839 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key)); | |
1840 | if (r < 0) | |
1841 | return r; | |
1842 | if (r > 0) | |
1843 | continue; | |
1844 | ||
1845 | switch (rr->key->type) { | |
1846 | ||
1847 | case DNS_TYPE_RRSIG: { | |
1848 | /* For each RRSIG we request the matching DNSKEY */ | |
1849 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *dnskey = NULL; | |
1850 | ||
1851 | /* If this RRSIG is about a DNSKEY RR and the | |
1852 | * signer is the same as the owner, then we | |
1853 | * already have the DNSKEY, and we don't have | |
1854 | * to look for more. */ | |
1855 | if (rr->rrsig.type_covered == DNS_TYPE_DNSKEY) { | |
1856 | r = dns_name_equal(rr->rrsig.signer, dns_resource_key_name(rr->key)); | |
1857 | if (r < 0) | |
1858 | return r; | |
1859 | if (r > 0) | |
1860 | continue; | |
1861 | } | |
1862 | ||
1863 | /* If the signer is not a parent of our | |
1864 | * original query, then this is about an | |
1865 | * auxiliary RRset, but not anything we asked | |
1866 | * for. In this case we aren't interested, | |
1867 | * because we don't want to request additional | |
1868 | * RRs for stuff we didn't really ask for, and | |
1869 | * also to avoid request loops, where | |
1870 | * additional RRs from one transaction result | |
1871 | * in another transaction whose additonal RRs | |
1872 | * point back to the original transaction, and | |
1873 | * we deadlock. */ | |
1874 | r = dns_name_endswith(dns_resource_key_name(t->key), rr->rrsig.signer); | |
1875 | if (r < 0) | |
1876 | return r; | |
1877 | if (r == 0) | |
1878 | continue; | |
1879 | ||
1880 | dnskey = dns_resource_key_new(rr->key->class, DNS_TYPE_DNSKEY, rr->rrsig.signer); | |
1881 | if (!dnskey) | |
1882 | return -ENOMEM; | |
1883 | ||
1884 | log_debug("Requesting DNSKEY to validate transaction %" PRIu16" (%s, RRSIG with key tag: %" PRIu16 ").", | |
1885 | t->id, dns_resource_key_name(rr->key), rr->rrsig.key_tag); | |
1886 | r = dns_transaction_request_dnssec_rr(t, dnskey); | |
1887 | if (r < 0) | |
1888 | return r; | |
1889 | break; | |
1890 | } | |
1891 | ||
1892 | case DNS_TYPE_DNSKEY: { | |
1893 | /* For each DNSKEY we request the matching DS */ | |
1894 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL; | |
1895 | ||
1896 | /* If the DNSKEY we are looking at is not for | |
1897 | * zone we are interested in, nor any of its | |
1898 | * parents, we aren't interested, and don't | |
1899 | * request it. After all, we don't want to end | |
1900 | * up in request loops, and want to keep | |
1901 | * additional traffic down. */ | |
1902 | ||
1903 | r = dns_name_endswith(dns_resource_key_name(t->key), dns_resource_key_name(rr->key)); | |
1904 | if (r < 0) | |
1905 | return r; | |
1906 | if (r == 0) | |
1907 | continue; | |
1908 | ||
1909 | ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key)); | |
1910 | if (!ds) | |
1911 | return -ENOMEM; | |
1912 | ||
1913 | log_debug("Requesting DS to validate transaction %" PRIu16" (%s, DNSKEY with key tag: %" PRIu16 ").", | |
1914 | t->id, dns_resource_key_name(rr->key), dnssec_keytag(rr, false)); | |
1915 | r = dns_transaction_request_dnssec_rr(t, ds); | |
1916 | if (r < 0) | |
1917 | return r; | |
1918 | ||
1919 | break; | |
1920 | } | |
1921 | ||
1922 | case DNS_TYPE_SOA: | |
1923 | case DNS_TYPE_NS: { | |
1924 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL; | |
1925 | ||
1926 | /* For an unsigned SOA or NS, try to acquire | |
1927 | * the matching DS RR, as we are at a zone cut | |
1928 | * then, and whether a DS exists tells us | |
1929 | * whether the zone is signed. Do so only if | |
1930 | * this RR matches our original question, | |
1931 | * however. */ | |
1932 | ||
1933 | r = dns_resource_key_match_rr(t->key, rr, NULL); | |
1934 | if (r < 0) | |
1935 | return r; | |
1936 | if (r == 0) | |
1937 | continue; | |
1938 | ||
1939 | r = dnssec_has_rrsig(t->answer, rr->key); | |
1940 | if (r < 0) | |
1941 | return r; | |
1942 | if (r > 0) | |
1943 | continue; | |
1944 | ||
1945 | ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key)); | |
1946 | if (!ds) | |
1947 | return -ENOMEM; | |
1948 | ||
1949 | log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned SOA/NS RRset).", | |
1950 | t->id, dns_resource_key_name(rr->key)); | |
1951 | r = dns_transaction_request_dnssec_rr(t, ds); | |
1952 | if (r < 0) | |
1953 | return r; | |
1954 | ||
1955 | break; | |
1956 | } | |
1957 | ||
1958 | case DNS_TYPE_DS: | |
1959 | case DNS_TYPE_CNAME: | |
1960 | case DNS_TYPE_DNAME: { | |
1961 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL; | |
1962 | const char *name; | |
1963 | ||
1964 | /* CNAMEs and DNAMEs cannot be located at a | |
1965 | * zone apex, hence ask for the parent SOA for | |
1966 | * unsigned CNAME/DNAME RRs, maybe that's the | |
1967 | * apex. But do all that only if this is | |
1968 | * actually a response to our original | |
1969 | * question. | |
1970 | * | |
1971 | * Similar for DS RRs, which are signed when | |
1972 | * the parent SOA is signed. */ | |
1973 | ||
1974 | r = dns_transaction_is_primary_response(t, rr); | |
1975 | if (r < 0) | |
1976 | return r; | |
1977 | if (r == 0) | |
1978 | continue; | |
1979 | ||
1980 | r = dnssec_has_rrsig(t->answer, rr->key); | |
1981 | if (r < 0) | |
1982 | return r; | |
1983 | if (r > 0) | |
1984 | continue; | |
1985 | ||
1986 | r = dns_answer_has_dname_for_cname(t->answer, rr); | |
1987 | if (r < 0) | |
1988 | return r; | |
1989 | if (r > 0) | |
1990 | continue; | |
1991 | ||
1992 | name = dns_resource_key_name(rr->key); | |
1993 | r = dns_name_parent(&name); | |
1994 | if (r < 0) | |
1995 | return r; | |
1996 | if (r == 0) | |
1997 | continue; | |
1998 | ||
1999 | soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, name); | |
2000 | if (!soa) | |
2001 | return -ENOMEM; | |
2002 | ||
2003 | log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned CNAME/DNAME/DS RRset).", | |
2004 | t->id, dns_resource_key_name(rr->key)); | |
2005 | r = dns_transaction_request_dnssec_rr(t, soa); | |
2006 | if (r < 0) | |
2007 | return r; | |
2008 | ||
2009 | break; | |
2010 | } | |
2011 | ||
2012 | default: { | |
2013 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL; | |
2014 | ||
2015 | /* For other unsigned RRsets (including | |
2016 | * NSEC/NSEC3!), look for proof the zone is | |
2017 | * unsigned, by requesting the SOA RR of the | |
2018 | * zone. However, do so only if they are | |
2019 | * directly relevant to our original | |
2020 | * question. */ | |
2021 | ||
2022 | r = dns_transaction_is_primary_response(t, rr); | |
2023 | if (r < 0) | |
2024 | return r; | |
2025 | if (r == 0) | |
2026 | continue; | |
2027 | ||
2028 | r = dnssec_has_rrsig(t->answer, rr->key); | |
2029 | if (r < 0) | |
2030 | return r; | |
2031 | if (r > 0) | |
2032 | continue; | |
2033 | ||
2034 | soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, dns_resource_key_name(rr->key)); | |
2035 | if (!soa) | |
2036 | return -ENOMEM; | |
2037 | ||
2038 | log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned non-SOA/NS RRset <%s>).", | |
2039 | t->id, dns_resource_key_name(rr->key), dns_resource_record_to_string(rr)); | |
2040 | r = dns_transaction_request_dnssec_rr(t, soa); | |
2041 | if (r < 0) | |
2042 | return r; | |
2043 | break; | |
2044 | }} | |
2045 | } | |
2046 | ||
2047 | /* Above, we requested everything necessary to validate what | |
2048 | * we got. Now, let's request what we need to validate what we | |
2049 | * didn't get... */ | |
2050 | ||
2051 | r = dns_transaction_has_unsigned_negative_answer(t); | |
2052 | if (r < 0) | |
2053 | return r; | |
2054 | if (r > 0) { | |
2055 | const char *name; | |
2056 | uint16_t type = 0; | |
2057 | ||
2058 | name = dns_resource_key_name(t->key); | |
2059 | ||
2060 | /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this | |
2061 | * could also be used as indication that we are not at a zone apex, but in real world setups there are | |
2062 | * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even | |
2063 | * though they have further children. If this was a DS request, then it's signed when the parent zone | |
2064 | * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR, | |
2065 | * to see if that is signed. */ | |
2066 | ||
2067 | if (t->key->type == DNS_TYPE_DS) { | |
2068 | r = dns_name_parent(&name); | |
2069 | if (r > 0) { | |
2070 | type = DNS_TYPE_SOA; | |
2071 | log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned empty DS response).", | |
2072 | t->id, dns_resource_key_name(t->key)); | |
2073 | } else | |
2074 | name = NULL; | |
2075 | ||
2076 | } else if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS)) { | |
2077 | ||
2078 | type = DNS_TYPE_DS; | |
2079 | log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned empty SOA/NS response).", | |
2080 | t->id, dns_resource_key_name(t->key)); | |
2081 | ||
2082 | } else { | |
2083 | type = DNS_TYPE_SOA; | |
2084 | log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned empty non-SOA/NS/DS response).", | |
2085 | t->id, dns_resource_key_name(t->key)); | |
2086 | } | |
2087 | ||
2088 | if (name) { | |
2089 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL; | |
2090 | ||
2091 | soa = dns_resource_key_new(t->key->class, type, name); | |
2092 | if (!soa) | |
2093 | return -ENOMEM; | |
2094 | ||
2095 | r = dns_transaction_request_dnssec_rr(t, soa); | |
2096 | if (r < 0) | |
2097 | return r; | |
2098 | } | |
2099 | } | |
2100 | ||
2101 | return dns_transaction_dnssec_is_live(t); | |
2102 | } | |
2103 | ||
2104 | void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source) { | |
2105 | assert(t); | |
2106 | assert(source); | |
2107 | ||
2108 | /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING, | |
2109 | we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If | |
2110 | the state is VALIDATING however, we should check if we are complete now. */ | |
2111 | ||
2112 | if (t->state == DNS_TRANSACTION_VALIDATING) | |
2113 | dns_transaction_process_dnssec(t); | |
2114 | } | |
2115 | ||
2116 | static int dns_transaction_validate_dnskey_by_ds(DnsTransaction *t) { | |
2117 | DnsResourceRecord *rr; | |
2118 | int ifindex, r; | |
2119 | ||
2120 | assert(t); | |
2121 | ||
2122 | /* Add all DNSKEY RRs from the answer that are validated by DS | |
2123 | * RRs from the list of validated keys to the list of | |
2124 | * validated keys. */ | |
2125 | ||
2126 | DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, t->answer) { | |
2127 | ||
2128 | r = dnssec_verify_dnskey_by_ds_search(rr, t->validated_keys); | |
2129 | if (r < 0) | |
2130 | return r; | |
2131 | if (r == 0) | |
2132 | continue; | |
2133 | ||
2134 | /* If so, the DNSKEY is validated too. */ | |
2135 | r = dns_answer_add_extend(&t->validated_keys, rr, ifindex, DNS_ANSWER_AUTHENTICATED); | |
2136 | if (r < 0) | |
2137 | return r; | |
2138 | } | |
2139 | ||
2140 | return 0; | |
2141 | } | |
2142 | ||
2143 | static int dns_transaction_requires_rrsig(DnsTransaction *t, DnsResourceRecord *rr) { | |
2144 | int r; | |
2145 | ||
2146 | assert(t); | |
2147 | assert(rr); | |
2148 | ||
2149 | /* Checks if the RR we are looking for must be signed with an | |
2150 | * RRSIG. This is used for positive responses. */ | |
2151 | ||
2152 | if (t->scope->dnssec_mode == DNSSEC_NO) | |
2153 | return false; | |
2154 | ||
2155 | if (dns_type_is_pseudo(rr->key->type)) | |
2156 | return -EINVAL; | |
2157 | ||
2158 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key)); | |
2159 | if (r < 0) | |
2160 | return r; | |
2161 | if (r > 0) | |
2162 | return false; | |
2163 | ||
2164 | switch (rr->key->type) { | |
2165 | ||
2166 | case DNS_TYPE_RRSIG: | |
2167 | /* RRSIGs are the signatures themselves, they need no signing. */ | |
2168 | return false; | |
2169 | ||
2170 | case DNS_TYPE_SOA: | |
2171 | case DNS_TYPE_NS: { | |
2172 | DnsTransaction *dt; | |
2173 | Iterator i; | |
2174 | ||
2175 | /* For SOA or NS RRs we look for a matching DS transaction */ | |
2176 | ||
2177 | SET_FOREACH(dt, t->dnssec_transactions, i) { | |
2178 | ||
2179 | if (dt->key->class != rr->key->class) | |
2180 | continue; | |
2181 | if (dt->key->type != DNS_TYPE_DS) | |
2182 | continue; | |
2183 | ||
2184 | r = dns_name_equal(dns_resource_key_name(dt->key), dns_resource_key_name(rr->key)); | |
2185 | if (r < 0) | |
2186 | return r; | |
2187 | if (r == 0) | |
2188 | continue; | |
2189 | ||
2190 | /* We found a DS transactions for the SOA/NS | |
2191 | * RRs we are looking at. If it discovered signed DS | |
2192 | * RRs, then we need to be signed, too. */ | |
2193 | ||
2194 | if (!dt->answer_authenticated) | |
2195 | return false; | |
2196 | ||
2197 | return dns_answer_match_key(dt->answer, dt->key, NULL); | |
2198 | } | |
2199 | ||
2200 | /* We found nothing that proves this is safe to leave | |
2201 | * this unauthenticated, hence ask inist on | |
2202 | * authentication. */ | |
2203 | return true; | |
2204 | } | |
2205 | ||
2206 | case DNS_TYPE_DS: | |
2207 | case DNS_TYPE_CNAME: | |
2208 | case DNS_TYPE_DNAME: { | |
2209 | const char *parent = NULL; | |
2210 | DnsTransaction *dt; | |
2211 | Iterator i; | |
2212 | ||
2213 | /* | |
2214 | * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA. | |
2215 | * | |
2216 | * DS RRs are signed if the parent is signed, hence also look at the parent SOA | |
2217 | */ | |
2218 | ||
2219 | SET_FOREACH(dt, t->dnssec_transactions, i) { | |
2220 | ||
2221 | if (dt->key->class != rr->key->class) | |
2222 | continue; | |
2223 | if (dt->key->type != DNS_TYPE_SOA) | |
2224 | continue; | |
2225 | ||
2226 | if (!parent) { | |
2227 | parent = dns_resource_key_name(rr->key); | |
2228 | r = dns_name_parent(&parent); | |
2229 | if (r < 0) | |
2230 | return r; | |
2231 | if (r == 0) { | |
2232 | if (rr->key->type == DNS_TYPE_DS) | |
2233 | return true; | |
2234 | ||
2235 | /* A CNAME/DNAME without a parent? That's sooo weird. */ | |
2236 | log_debug("Transaction %" PRIu16 " claims CNAME/DNAME at root. Refusing.", t->id); | |
2237 | return -EBADMSG; | |
2238 | } | |
2239 | } | |
2240 | ||
2241 | r = dns_name_equal(dns_resource_key_name(dt->key), parent); | |
2242 | if (r < 0) | |
2243 | return r; | |
2244 | if (r == 0) | |
2245 | continue; | |
2246 | ||
2247 | return t->answer_authenticated; | |
2248 | } | |
2249 | ||
2250 | return true; | |
2251 | } | |
2252 | ||
2253 | default: { | |
2254 | DnsTransaction *dt; | |
2255 | Iterator i; | |
2256 | ||
2257 | /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */ | |
2258 | ||
2259 | SET_FOREACH(dt, t->dnssec_transactions, i) { | |
2260 | ||
2261 | if (dt->key->class != rr->key->class) | |
2262 | continue; | |
2263 | if (dt->key->type != DNS_TYPE_SOA) | |
2264 | continue; | |
2265 | ||
2266 | r = dns_name_equal(dns_resource_key_name(dt->key), dns_resource_key_name(rr->key)); | |
2267 | if (r < 0) | |
2268 | return r; | |
2269 | if (r == 0) | |
2270 | continue; | |
2271 | ||
2272 | /* We found the transaction that was supposed to find | |
2273 | * the SOA RR for us. It was successful, but found no | |
2274 | * RR for us. This means we are not at a zone cut. In | |
2275 | * this case, we require authentication if the SOA | |
2276 | * lookup was authenticated too. */ | |
2277 | return t->answer_authenticated; | |
2278 | } | |
2279 | ||
2280 | return true; | |
2281 | }} | |
2282 | } | |
2283 | ||
2284 | static int dns_transaction_in_private_tld(DnsTransaction *t, const DnsResourceKey *key) { | |
2285 | DnsTransaction *dt; | |
2286 | const char *tld; | |
2287 | Iterator i; | |
2288 | int r; | |
2289 | ||
2290 | /* If DNSSEC downgrade mode is on, checks whether the | |
2291 | * specified RR is one level below a TLD we have proven not to | |
2292 | * exist. In such a case we assume that this is a private | |
2293 | * domain, and permit it. | |
2294 | * | |
2295 | * This detects cases like the Fritz!Box router networks. Each | |
2296 | * Fritz!Box router serves a private "fritz.box" zone, in the | |
2297 | * non-existing TLD "box". Requests for the "fritz.box" domain | |
2298 | * are served by the router itself, while requests for the | |
2299 | * "box" domain will result in NXDOMAIN. | |
2300 | * | |
2301 | * Note that this logic is unable to detect cases where a | |
2302 | * router serves a private DNS zone directly under | |
2303 | * non-existing TLD. In such a case we cannot detect whether | |
2304 | * the TLD is supposed to exist or not, as all requests we | |
2305 | * make for it will be answered by the router's zone, and not | |
2306 | * by the root zone. */ | |
2307 | ||
2308 | assert(t); | |
2309 | ||
2310 | if (t->scope->dnssec_mode != DNSSEC_ALLOW_DOWNGRADE) | |
2311 | return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */ | |
2312 | ||
2313 | tld = dns_resource_key_name(key); | |
2314 | r = dns_name_parent(&tld); | |
2315 | if (r < 0) | |
2316 | return r; | |
2317 | if (r == 0) | |
2318 | return false; /* Already the root domain */ | |
2319 | ||
2320 | if (!dns_name_is_single_label(tld)) | |
2321 | return false; | |
2322 | ||
2323 | SET_FOREACH(dt, t->dnssec_transactions, i) { | |
2324 | ||
2325 | if (dt->key->class != key->class) | |
2326 | continue; | |
2327 | ||
2328 | r = dns_name_equal(dns_resource_key_name(dt->key), tld); | |
2329 | if (r < 0) | |
2330 | return r; | |
2331 | if (r == 0) | |
2332 | continue; | |
2333 | ||
2334 | /* We found an auxiliary lookup we did for the TLD. If | |
2335 | * that returned with NXDOMAIN, we know the TLD didn't | |
2336 | * exist, and hence this might be a private zone. */ | |
2337 | ||
2338 | return dt->answer_rcode == DNS_RCODE_NXDOMAIN; | |
2339 | } | |
2340 | ||
2341 | return false; | |
2342 | } | |
2343 | ||
2344 | static int dns_transaction_requires_nsec(DnsTransaction *t) { | |
2345 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
2346 | DnsTransaction *dt; | |
2347 | const char *name; | |
2348 | uint16_t type = 0; | |
2349 | Iterator i; | |
2350 | int r; | |
2351 | ||
2352 | assert(t); | |
2353 | ||
2354 | /* Checks if we need to insist on NSEC/NSEC3 RRs for proving | |
2355 | * this negative reply */ | |
2356 | ||
2357 | if (t->scope->dnssec_mode == DNSSEC_NO) | |
2358 | return false; | |
2359 | ||
2360 | if (dns_type_is_pseudo(t->key->type)) | |
2361 | return -EINVAL; | |
2362 | ||
2363 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(t->key)); | |
2364 | if (r < 0) | |
2365 | return r; | |
2366 | if (r > 0) | |
2367 | return false; | |
2368 | ||
2369 | r = dns_transaction_in_private_tld(t, t->key); | |
2370 | if (r < 0) | |
2371 | return r; | |
2372 | if (r > 0) { | |
2373 | /* The lookup is from a TLD that is proven not to | |
2374 | * exist, and we are in downgrade mode, hence ignore | |
2375 | * that fact that we didn't get any NSEC RRs.*/ | |
2376 | ||
2377 | log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.", | |
2378 | dns_resource_key_to_string(t->key, key_str, sizeof key_str)); | |
2379 | return false; | |
2380 | } | |
2381 | ||
2382 | name = dns_resource_key_name(t->key); | |
2383 | ||
2384 | if (t->key->type == DNS_TYPE_DS) { | |
2385 | ||
2386 | /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed, | |
2387 | * hence check the parent SOA in this case. */ | |
2388 | ||
2389 | r = dns_name_parent(&name); | |
2390 | if (r < 0) | |
2391 | return r; | |
2392 | if (r == 0) | |
2393 | return true; | |
2394 | ||
2395 | type = DNS_TYPE_SOA; | |
2396 | ||
2397 | } else if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS)) | |
2398 | /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */ | |
2399 | type = DNS_TYPE_DS; | |
2400 | else | |
2401 | /* For all other negative replies, check for the SOA lookup */ | |
2402 | type = DNS_TYPE_SOA; | |
2403 | ||
2404 | /* For all other RRs we check the SOA on the same level to see | |
2405 | * if it's signed. */ | |
2406 | ||
2407 | SET_FOREACH(dt, t->dnssec_transactions, i) { | |
2408 | ||
2409 | if (dt->key->class != t->key->class) | |
2410 | continue; | |
2411 | if (dt->key->type != type) | |
2412 | continue; | |
2413 | ||
2414 | r = dns_name_equal(dns_resource_key_name(dt->key), name); | |
2415 | if (r < 0) | |
2416 | return r; | |
2417 | if (r == 0) | |
2418 | continue; | |
2419 | ||
2420 | return dt->answer_authenticated; | |
2421 | } | |
2422 | ||
2423 | /* If in doubt, require NSEC/NSEC3 */ | |
2424 | return true; | |
2425 | } | |
2426 | ||
2427 | static int dns_transaction_dnskey_authenticated(DnsTransaction *t, DnsResourceRecord *rr) { | |
2428 | DnsResourceRecord *rrsig; | |
2429 | bool found = false; | |
2430 | int r; | |
2431 | ||
2432 | /* Checks whether any of the DNSKEYs used for the RRSIGs for | |
2433 | * the specified RRset is authenticated (i.e. has a matching | |
2434 | * DS RR). */ | |
2435 | ||
2436 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key)); | |
2437 | if (r < 0) | |
2438 | return r; | |
2439 | if (r > 0) | |
2440 | return false; | |
2441 | ||
2442 | DNS_ANSWER_FOREACH(rrsig, t->answer) { | |
2443 | DnsTransaction *dt; | |
2444 | Iterator i; | |
2445 | ||
2446 | r = dnssec_key_match_rrsig(rr->key, rrsig); | |
2447 | if (r < 0) | |
2448 | return r; | |
2449 | if (r == 0) | |
2450 | continue; | |
2451 | ||
2452 | SET_FOREACH(dt, t->dnssec_transactions, i) { | |
2453 | ||
2454 | if (dt->key->class != rr->key->class) | |
2455 | continue; | |
2456 | ||
2457 | if (dt->key->type == DNS_TYPE_DNSKEY) { | |
2458 | ||
2459 | r = dns_name_equal(dns_resource_key_name(dt->key), rrsig->rrsig.signer); | |
2460 | if (r < 0) | |
2461 | return r; | |
2462 | if (r == 0) | |
2463 | continue; | |
2464 | ||
2465 | /* OK, we found an auxiliary DNSKEY | |
2466 | * lookup. If that lookup is | |
2467 | * authenticated, report this. */ | |
2468 | ||
2469 | if (dt->answer_authenticated) | |
2470 | return true; | |
2471 | ||
2472 | found = true; | |
2473 | ||
2474 | } else if (dt->key->type == DNS_TYPE_DS) { | |
2475 | ||
2476 | r = dns_name_equal(dns_resource_key_name(dt->key), rrsig->rrsig.signer); | |
2477 | if (r < 0) | |
2478 | return r; | |
2479 | if (r == 0) | |
2480 | continue; | |
2481 | ||
2482 | /* OK, we found an auxiliary DS | |
2483 | * lookup. If that lookup is | |
2484 | * authenticated and non-zero, we | |
2485 | * won! */ | |
2486 | ||
2487 | if (!dt->answer_authenticated) | |
2488 | return false; | |
2489 | ||
2490 | return dns_answer_match_key(dt->answer, dt->key, NULL); | |
2491 | } | |
2492 | } | |
2493 | } | |
2494 | ||
2495 | return found ? false : -ENXIO; | |
2496 | } | |
2497 | ||
2498 | static int dns_transaction_known_signed(DnsTransaction *t, DnsResourceRecord *rr) { | |
2499 | assert(t); | |
2500 | assert(rr); | |
2501 | ||
2502 | /* We know that the root domain is signed, hence if it appears | |
2503 | * not to be signed, there's a problem with the DNS server */ | |
2504 | ||
2505 | return rr->key->class == DNS_CLASS_IN && | |
2506 | dns_name_is_root(dns_resource_key_name(rr->key)); | |
2507 | } | |
2508 | ||
2509 | static int dns_transaction_check_revoked_trust_anchors(DnsTransaction *t) { | |
2510 | DnsResourceRecord *rr; | |
2511 | int r; | |
2512 | ||
2513 | assert(t); | |
2514 | ||
2515 | /* Maybe warn the user that we encountered a revoked DNSKEY | |
2516 | * for a key from our trust anchor. Note that we don't care | |
2517 | * whether the DNSKEY can be authenticated or not. It's | |
2518 | * sufficient if it is self-signed. */ | |
2519 | ||
2520 | DNS_ANSWER_FOREACH(rr, t->answer) { | |
2521 | r = dns_trust_anchor_check_revoked(&t->scope->manager->trust_anchor, rr, t->answer); | |
2522 | if (r < 0) | |
2523 | return r; | |
2524 | } | |
2525 | ||
2526 | return 0; | |
2527 | } | |
2528 | ||
2529 | static int dns_transaction_invalidate_revoked_keys(DnsTransaction *t) { | |
2530 | bool changed; | |
2531 | int r; | |
2532 | ||
2533 | assert(t); | |
2534 | ||
2535 | /* Removes all DNSKEY/DS objects from t->validated_keys that | |
2536 | * our trust anchors database considers revoked. */ | |
2537 | ||
2538 | do { | |
2539 | DnsResourceRecord *rr; | |
2540 | ||
2541 | changed = false; | |
2542 | ||
2543 | DNS_ANSWER_FOREACH(rr, t->validated_keys) { | |
2544 | r = dns_trust_anchor_is_revoked(&t->scope->manager->trust_anchor, rr); | |
2545 | if (r < 0) | |
2546 | return r; | |
2547 | if (r > 0) { | |
2548 | r = dns_answer_remove_by_rr(&t->validated_keys, rr); | |
2549 | if (r < 0) | |
2550 | return r; | |
2551 | ||
2552 | assert(r > 0); | |
2553 | changed = true; | |
2554 | break; | |
2555 | } | |
2556 | } | |
2557 | } while (changed); | |
2558 | ||
2559 | return 0; | |
2560 | } | |
2561 | ||
2562 | static int dns_transaction_copy_validated(DnsTransaction *t) { | |
2563 | DnsTransaction *dt; | |
2564 | Iterator i; | |
2565 | int r; | |
2566 | ||
2567 | assert(t); | |
2568 | ||
2569 | /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */ | |
2570 | ||
2571 | SET_FOREACH(dt, t->dnssec_transactions, i) { | |
2572 | ||
2573 | if (DNS_TRANSACTION_IS_LIVE(dt->state)) | |
2574 | continue; | |
2575 | ||
2576 | if (!dt->answer_authenticated) | |
2577 | continue; | |
2578 | ||
2579 | r = dns_answer_extend(&t->validated_keys, dt->answer); | |
2580 | if (r < 0) | |
2581 | return r; | |
2582 | } | |
2583 | ||
2584 | return 0; | |
2585 | } | |
2586 | ||
2587 | typedef enum { | |
2588 | DNSSEC_PHASE_DNSKEY, /* Phase #1, only validate DNSKEYs */ | |
2589 | DNSSEC_PHASE_NSEC, /* Phase #2, only validate NSEC+NSEC3 */ | |
2590 | DNSSEC_PHASE_ALL, /* Phase #3, validate everything else */ | |
2591 | } Phase; | |
2592 | ||
2593 | static int dnssec_validate_records( | |
2594 | DnsTransaction *t, | |
2595 | Phase phase, | |
2596 | bool *have_nsec, | |
2597 | DnsAnswer **validated) { | |
2598 | ||
2599 | DnsResourceRecord *rr; | |
2600 | int r; | |
2601 | ||
2602 | /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */ | |
2603 | ||
2604 | DNS_ANSWER_FOREACH(rr, t->answer) { | |
2605 | DnsResourceRecord *rrsig = NULL; | |
2606 | DnssecResult result; | |
2607 | ||
2608 | switch (rr->key->type) { | |
2609 | case DNS_TYPE_RRSIG: | |
2610 | continue; | |
2611 | ||
2612 | case DNS_TYPE_DNSKEY: | |
2613 | /* We validate DNSKEYs only in the DNSKEY and ALL phases */ | |
2614 | if (phase == DNSSEC_PHASE_NSEC) | |
2615 | continue; | |
2616 | break; | |
2617 | ||
2618 | case DNS_TYPE_NSEC: | |
2619 | case DNS_TYPE_NSEC3: | |
2620 | *have_nsec = true; | |
2621 | ||
2622 | /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */ | |
2623 | if (phase == DNSSEC_PHASE_DNSKEY) | |
2624 | continue; | |
2625 | break; | |
2626 | ||
2627 | default: | |
2628 | /* We validate all other RRs only in the ALL phases */ | |
2629 | if (phase != DNSSEC_PHASE_ALL) | |
2630 | continue; | |
2631 | } | |
2632 | ||
2633 | r = dnssec_verify_rrset_search(t->answer, rr->key, t->validated_keys, USEC_INFINITY, &result, &rrsig); | |
2634 | if (r < 0) | |
2635 | return r; | |
2636 | ||
2637 | log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr)), dnssec_result_to_string(result)); | |
2638 | ||
2639 | if (result == DNSSEC_VALIDATED) { | |
2640 | ||
2641 | if (rr->key->type == DNS_TYPE_DNSKEY) { | |
2642 | /* If we just validated a DNSKEY RRset, then let's add these keys to | |
2643 | * the set of validated keys for this transaction. */ | |
2644 | ||
2645 | r = dns_answer_copy_by_key(&t->validated_keys, t->answer, rr->key, DNS_ANSWER_AUTHENTICATED); | |
2646 | if (r < 0) | |
2647 | return r; | |
2648 | ||
2649 | /* Some of the DNSKEYs we just added might already have been revoked, | |
2650 | * remove them again in that case. */ | |
2651 | r = dns_transaction_invalidate_revoked_keys(t); | |
2652 | if (r < 0) | |
2653 | return r; | |
2654 | } | |
2655 | ||
2656 | /* Add the validated RRset to the new list of validated | |
2657 | * RRsets, and remove it from the unvalidated RRsets. | |
2658 | * We mark the RRset as authenticated and cacheable. */ | |
2659 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE); | |
2660 | if (r < 0) | |
2661 | return r; | |
2662 | ||
2663 | manager_dnssec_verdict(t->scope->manager, DNSSEC_SECURE, rr->key); | |
2664 | ||
2665 | /* Exit the loop, we dropped something from the answer, start from the beginning */ | |
2666 | return 1; | |
2667 | } | |
2668 | ||
2669 | /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as | |
2670 | * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet, | |
2671 | * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */ | |
2672 | if (phase != DNSSEC_PHASE_ALL) | |
2673 | continue; | |
2674 | ||
2675 | if (result == DNSSEC_VALIDATED_WILDCARD) { | |
2676 | bool authenticated = false; | |
2677 | const char *source; | |
2678 | ||
2679 | /* This RRset validated, but as a wildcard. This means we need | |
2680 | * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists.*/ | |
2681 | ||
2682 | /* First step, determine the source of synthesis */ | |
2683 | r = dns_resource_record_source(rrsig, &source); | |
2684 | if (r < 0) | |
2685 | return r; | |
2686 | ||
2687 | r = dnssec_test_positive_wildcard(*validated, | |
2688 | dns_resource_key_name(rr->key), | |
2689 | source, | |
2690 | rrsig->rrsig.signer, | |
2691 | &authenticated); | |
2692 | ||
2693 | /* Unless the NSEC proof showed that the key really doesn't exist something is off. */ | |
2694 | if (r == 0) | |
2695 | result = DNSSEC_INVALID; | |
2696 | else { | |
2697 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, | |
2698 | authenticated ? (DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE) : 0); | |
2699 | if (r < 0) | |
2700 | return r; | |
2701 | ||
2702 | manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, rr->key); | |
2703 | ||
2704 | /* Exit the loop, we dropped something from the answer, start from the beginning */ | |
2705 | return 1; | |
2706 | } | |
2707 | } | |
2708 | ||
2709 | if (result == DNSSEC_NO_SIGNATURE) { | |
2710 | r = dns_transaction_requires_rrsig(t, rr); | |
2711 | if (r < 0) | |
2712 | return r; | |
2713 | if (r == 0) { | |
2714 | /* Data does not require signing. In that case, just copy it over, | |
2715 | * but remember that this is by no means authenticated.*/ | |
2716 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0); | |
2717 | if (r < 0) | |
2718 | return r; | |
2719 | ||
2720 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); | |
2721 | return 1; | |
2722 | } | |
2723 | ||
2724 | r = dns_transaction_known_signed(t, rr); | |
2725 | if (r < 0) | |
2726 | return r; | |
2727 | if (r > 0) { | |
2728 | /* This is an RR we know has to be signed. If it isn't this means | |
2729 | * the server is not attaching RRSIGs, hence complain. */ | |
2730 | ||
2731 | dns_server_packet_rrsig_missing(t->server, t->current_feature_level); | |
2732 | ||
2733 | if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) { | |
2734 | ||
2735 | /* Downgrading is OK? If so, just consider the information unsigned */ | |
2736 | ||
2737 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0); | |
2738 | if (r < 0) | |
2739 | return r; | |
2740 | ||
2741 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); | |
2742 | return 1; | |
2743 | } | |
2744 | ||
2745 | /* Otherwise, fail */ | |
2746 | t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER; | |
2747 | return 0; | |
2748 | } | |
2749 | ||
2750 | r = dns_transaction_in_private_tld(t, rr->key); | |
2751 | if (r < 0) | |
2752 | return r; | |
2753 | if (r > 0) { | |
2754 | char s[DNS_RESOURCE_KEY_STRING_MAX]; | |
2755 | ||
2756 | /* The data is from a TLD that is proven not to exist, and we are in downgrade | |
2757 | * mode, hence ignore the fact that this was not signed. */ | |
2758 | ||
2759 | log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.", | |
2760 | dns_resource_key_to_string(rr->key, s, sizeof s)); | |
2761 | ||
2762 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0); | |
2763 | if (r < 0) | |
2764 | return r; | |
2765 | ||
2766 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); | |
2767 | return 1; | |
2768 | } | |
2769 | } | |
2770 | ||
2771 | if (IN_SET(result, | |
2772 | DNSSEC_MISSING_KEY, | |
2773 | DNSSEC_SIGNATURE_EXPIRED, | |
2774 | DNSSEC_UNSUPPORTED_ALGORITHM)) { | |
2775 | ||
2776 | r = dns_transaction_dnskey_authenticated(t, rr); | |
2777 | if (r < 0 && r != -ENXIO) | |
2778 | return r; | |
2779 | if (r == 0) { | |
2780 | /* The DNSKEY transaction was not authenticated, this means there's | |
2781 | * no DS for this, which means it's OK if no keys are found for this signature. */ | |
2782 | ||
2783 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0); | |
2784 | if (r < 0) | |
2785 | return r; | |
2786 | ||
2787 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); | |
2788 | return 1; | |
2789 | } | |
2790 | } | |
2791 | ||
2792 | r = dns_transaction_is_primary_response(t, rr); | |
2793 | if (r < 0) | |
2794 | return r; | |
2795 | if (r > 0) { | |
2796 | /* Look for a matching DNAME for this CNAME */ | |
2797 | r = dns_answer_has_dname_for_cname(t->answer, rr); | |
2798 | if (r < 0) | |
2799 | return r; | |
2800 | if (r == 0) { | |
2801 | /* Also look among the stuff we already validated */ | |
2802 | r = dns_answer_has_dname_for_cname(*validated, rr); | |
2803 | if (r < 0) | |
2804 | return r; | |
2805 | } | |
2806 | ||
2807 | if (r == 0) { | |
2808 | if (IN_SET(result, | |
2809 | DNSSEC_INVALID, | |
2810 | DNSSEC_SIGNATURE_EXPIRED, | |
2811 | DNSSEC_NO_SIGNATURE)) | |
2812 | manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, rr->key); | |
2813 | else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */ | |
2814 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, rr->key); | |
2815 | ||
2816 | /* This is a primary response to our question, and it failed validation. | |
2817 | * That's fatal. */ | |
2818 | t->answer_dnssec_result = result; | |
2819 | return 0; | |
2820 | } | |
2821 | ||
2822 | /* This is a primary response, but we do have a DNAME RR | |
2823 | * in the RR that can replay this CNAME, hence rely on | |
2824 | * that, and we can remove the CNAME in favour of it. */ | |
2825 | } | |
2826 | ||
2827 | /* This is just some auxiliary data. Just remove the RRset and continue. */ | |
2828 | r = dns_answer_remove_by_key(&t->answer, rr->key); | |
2829 | if (r < 0) | |
2830 | return r; | |
2831 | ||
2832 | /* We dropped something from the answer, start from the beginning. */ | |
2833 | return 1; | |
2834 | } | |
2835 | ||
2836 | return 2; /* Finito. */ | |
2837 | } | |
2838 | ||
2839 | int dns_transaction_validate_dnssec(DnsTransaction *t) { | |
2840 | _cleanup_(dns_answer_unrefp) DnsAnswer *validated = NULL; | |
2841 | Phase phase; | |
2842 | DnsAnswerFlags flags; | |
2843 | int r; | |
2844 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
2845 | ||
2846 | assert(t); | |
2847 | ||
2848 | /* We have now collected all DS and DNSKEY RRs in | |
2849 | * t->validated_keys, let's see which RRs we can now | |
2850 | * authenticate with that. */ | |
2851 | ||
2852 | if (t->scope->dnssec_mode == DNSSEC_NO) | |
2853 | return 0; | |
2854 | ||
2855 | /* Already validated */ | |
2856 | if (t->answer_dnssec_result != _DNSSEC_RESULT_INVALID) | |
2857 | return 0; | |
2858 | ||
2859 | /* Our own stuff needs no validation */ | |
2860 | if (IN_SET(t->answer_source, DNS_TRANSACTION_ZONE, DNS_TRANSACTION_TRUST_ANCHOR)) { | |
2861 | t->answer_dnssec_result = DNSSEC_VALIDATED; | |
2862 | t->answer_authenticated = true; | |
2863 | return 0; | |
2864 | } | |
2865 | ||
2866 | /* Cached stuff is not affected by validation. */ | |
2867 | if (t->answer_source != DNS_TRANSACTION_NETWORK) | |
2868 | return 0; | |
2869 | ||
2870 | if (!dns_transaction_dnssec_supported_full(t)) { | |
2871 | /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */ | |
2872 | t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER; | |
2873 | log_debug("Not validating response for %" PRIu16 ", server lacks DNSSEC support.", t->id); | |
2874 | return 0; | |
2875 | } | |
2876 | ||
2877 | log_debug("Validating response from transaction %" PRIu16 " (%s).", | |
2878 | t->id, | |
2879 | dns_resource_key_to_string(t->key, key_str, sizeof key_str)); | |
2880 | ||
2881 | /* First, see if this response contains any revoked trust | |
2882 | * anchors we care about */ | |
2883 | r = dns_transaction_check_revoked_trust_anchors(t); | |
2884 | if (r < 0) | |
2885 | return r; | |
2886 | ||
2887 | /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */ | |
2888 | r = dns_transaction_copy_validated(t); | |
2889 | if (r < 0) | |
2890 | return r; | |
2891 | ||
2892 | /* Second, see if there are DNSKEYs we already know a | |
2893 | * validated DS for. */ | |
2894 | r = dns_transaction_validate_dnskey_by_ds(t); | |
2895 | if (r < 0) | |
2896 | return r; | |
2897 | ||
2898 | /* Fourth, remove all DNSKEY and DS RRs again that our trust | |
2899 | * anchor says are revoked. After all we might have marked | |
2900 | * some keys revoked above, but they might still be lingering | |
2901 | * in our validated_keys list. */ | |
2902 | r = dns_transaction_invalidate_revoked_keys(t); | |
2903 | if (r < 0) | |
2904 | return r; | |
2905 | ||
2906 | phase = DNSSEC_PHASE_DNSKEY; | |
2907 | for (;;) { | |
2908 | bool have_nsec = false; | |
2909 | ||
2910 | r = dnssec_validate_records(t, phase, &have_nsec, &validated); | |
2911 | if (r <= 0) | |
2912 | return r; | |
2913 | ||
2914 | /* Try again as long as we managed to achieve something */ | |
2915 | if (r == 1) | |
2916 | continue; | |
2917 | ||
2918 | if (phase == DNSSEC_PHASE_DNSKEY && have_nsec) { | |
2919 | /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */ | |
2920 | phase = DNSSEC_PHASE_NSEC; | |
2921 | continue; | |
2922 | } | |
2923 | ||
2924 | if (phase != DNSSEC_PHASE_ALL) { | |
2925 | /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now. | |
2926 | * Note that in this third phase we start to remove RRs we couldn't validate. */ | |
2927 | phase = DNSSEC_PHASE_ALL; | |
2928 | continue; | |
2929 | } | |
2930 | ||
2931 | /* We're done */ | |
2932 | break; | |
2933 | } | |
2934 | ||
2935 | dns_answer_unref(t->answer); | |
2936 | t->answer = validated; | |
2937 | validated = NULL; | |
2938 | ||
2939 | /* At this point the answer only contains validated | |
2940 | * RRsets. Now, let's see if it actually answers the question | |
2941 | * we asked. If so, great! If it doesn't, then see if | |
2942 | * NSEC/NSEC3 can prove this. */ | |
2943 | r = dns_transaction_has_positive_answer(t, &flags); | |
2944 | if (r > 0) { | |
2945 | /* Yes, it answers the question! */ | |
2946 | ||
2947 | if (flags & DNS_ANSWER_AUTHENTICATED) { | |
2948 | /* The answer is fully authenticated, yay. */ | |
2949 | t->answer_dnssec_result = DNSSEC_VALIDATED; | |
2950 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
2951 | t->answer_authenticated = true; | |
2952 | } else { | |
2953 | /* The answer is not fully authenticated. */ | |
2954 | t->answer_dnssec_result = DNSSEC_UNSIGNED; | |
2955 | t->answer_authenticated = false; | |
2956 | } | |
2957 | ||
2958 | } else if (r == 0) { | |
2959 | DnssecNsecResult nr; | |
2960 | bool authenticated = false; | |
2961 | ||
2962 | /* Bummer! Let's check NSEC/NSEC3 */ | |
2963 | r = dnssec_nsec_test(t->answer, t->key, &nr, &authenticated, &t->answer_nsec_ttl); | |
2964 | if (r < 0) | |
2965 | return r; | |
2966 | ||
2967 | switch (nr) { | |
2968 | ||
2969 | case DNSSEC_NSEC_NXDOMAIN: | |
2970 | /* NSEC proves the domain doesn't exist. Very good. */ | |
2971 | log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str); | |
2972 | t->answer_dnssec_result = DNSSEC_VALIDATED; | |
2973 | t->answer_rcode = DNS_RCODE_NXDOMAIN; | |
2974 | t->answer_authenticated = authenticated; | |
2975 | ||
2976 | manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, t->key); | |
2977 | break; | |
2978 | ||
2979 | case DNSSEC_NSEC_NODATA: | |
2980 | /* NSEC proves that there's no data here, very good. */ | |
2981 | log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str); | |
2982 | t->answer_dnssec_result = DNSSEC_VALIDATED; | |
2983 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
2984 | t->answer_authenticated = authenticated; | |
2985 | ||
2986 | manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, t->key); | |
2987 | break; | |
2988 | ||
2989 | case DNSSEC_NSEC_OPTOUT: | |
2990 | /* NSEC3 says the data might not be signed */ | |
2991 | log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str); | |
2992 | t->answer_dnssec_result = DNSSEC_UNSIGNED; | |
2993 | t->answer_authenticated = false; | |
2994 | ||
2995 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, t->key); | |
2996 | break; | |
2997 | ||
2998 | case DNSSEC_NSEC_NO_RR: | |
2999 | /* No NSEC data? Bummer! */ | |
3000 | ||
3001 | r = dns_transaction_requires_nsec(t); | |
3002 | if (r < 0) | |
3003 | return r; | |
3004 | if (r > 0) { | |
3005 | t->answer_dnssec_result = DNSSEC_NO_SIGNATURE; | |
3006 | manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, t->key); | |
3007 | } else { | |
3008 | t->answer_dnssec_result = DNSSEC_UNSIGNED; | |
3009 | t->answer_authenticated = false; | |
3010 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, t->key); | |
3011 | } | |
3012 | ||
3013 | break; | |
3014 | ||
3015 | case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM: | |
3016 | /* We don't know the NSEC3 algorithm used? */ | |
3017 | t->answer_dnssec_result = DNSSEC_UNSUPPORTED_ALGORITHM; | |
3018 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, t->key); | |
3019 | break; | |
3020 | ||
3021 | case DNSSEC_NSEC_FOUND: | |
3022 | case DNSSEC_NSEC_CNAME: | |
3023 | /* NSEC says it needs to be there, but we couldn't find it? Bummer! */ | |
3024 | t->answer_dnssec_result = DNSSEC_NSEC_MISMATCH; | |
3025 | manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, t->key); | |
3026 | break; | |
3027 | ||
3028 | default: | |
3029 | assert_not_reached("Unexpected NSEC result."); | |
3030 | } | |
3031 | } | |
3032 | ||
3033 | return 1; | |
3034 | } | |
3035 | ||
3036 | static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] = { | |
3037 | [DNS_TRANSACTION_NULL] = "null", | |
3038 | [DNS_TRANSACTION_PENDING] = "pending", | |
3039 | [DNS_TRANSACTION_VALIDATING] = "validating", | |
3040 | [DNS_TRANSACTION_RCODE_FAILURE] = "rcode-failure", | |
3041 | [DNS_TRANSACTION_SUCCESS] = "success", | |
3042 | [DNS_TRANSACTION_NO_SERVERS] = "no-servers", | |
3043 | [DNS_TRANSACTION_TIMEOUT] = "timeout", | |
3044 | [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED] = "attempts-max-reached", | |
3045 | [DNS_TRANSACTION_INVALID_REPLY] = "invalid-reply", | |
3046 | [DNS_TRANSACTION_ERRNO] = "errno", | |
3047 | [DNS_TRANSACTION_ABORTED] = "aborted", | |
3048 | [DNS_TRANSACTION_DNSSEC_FAILED] = "dnssec-failed", | |
3049 | [DNS_TRANSACTION_NO_TRUST_ANCHOR] = "no-trust-anchor", | |
3050 | [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED] = "rr-type-unsupported", | |
3051 | [DNS_TRANSACTION_NETWORK_DOWN] = "network-down", | |
3052 | [DNS_TRANSACTION_NOT_FOUND] = "not-found", | |
3053 | }; | |
3054 | DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state, DnsTransactionState); | |
3055 | ||
3056 | static const char* const dns_transaction_source_table[_DNS_TRANSACTION_SOURCE_MAX] = { | |
3057 | [DNS_TRANSACTION_NETWORK] = "network", | |
3058 | [DNS_TRANSACTION_CACHE] = "cache", | |
3059 | [DNS_TRANSACTION_ZONE] = "zone", | |
3060 | [DNS_TRANSACTION_TRUST_ANCHOR] = "trust-anchor", | |
3061 | }; | |
3062 | DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source, DnsTransactionSource); |