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1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ | |
2 | ||
3 | #include "sd-event.h" | |
4 | #include "sd-messages.h" | |
5 | ||
6 | #include "af-list.h" | |
7 | #include "alloc-util.h" | |
8 | #include "dns-domain.h" | |
9 | #include "errno-list.h" | |
10 | #include "errno-util.h" | |
11 | #include "fd-util.h" | |
12 | #include "glyph-util.h" | |
13 | #include "log.h" | |
14 | #include "random-util.h" | |
15 | #include "resolved-dns-answer.h" | |
16 | #include "resolved-dns-cache.h" | |
17 | #include "resolved-dns-packet.h" | |
18 | #include "resolved-dns-query.h" | |
19 | #include "resolved-dns-question.h" | |
20 | #include "resolved-dns-rr.h" | |
21 | #include "resolved-dns-scope.h" | |
22 | #include "resolved-dns-server.h" | |
23 | #include "resolved-dns-stream.h" | |
24 | #include "resolved-dns-transaction.h" | |
25 | #include "resolved-dnstls.h" | |
26 | #include "resolved-link.h" | |
27 | #include "resolved-llmnr.h" | |
28 | #include "resolved-manager.h" | |
29 | #include "resolved-socket-graveyard.h" | |
30 | #include "resolved-timeouts.h" | |
31 | #include "set.h" | |
32 | #include "string-table.h" | |
33 | #include "string-util.h" | |
34 | ||
35 | #define TRANSACTIONS_MAX 4096 | |
36 | ||
37 | static void dns_transaction_reset_answer(DnsTransaction *t) { | |
38 | assert(t); | |
39 | ||
40 | t->received = dns_packet_unref(t->received); | |
41 | t->answer = dns_answer_unref(t->answer); | |
42 | t->answer_rcode = 0; | |
43 | t->answer_ede_rcode = _DNS_EDE_RCODE_INVALID; | |
44 | t->answer_ede_msg = mfree(t->answer_ede_msg); | |
45 | t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; | |
46 | t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID; | |
47 | t->answer_query_flags = 0; | |
48 | t->answer_nsec_ttl = UINT32_MAX; | |
49 | t->answer_errno = 0; | |
50 | } | |
51 | ||
52 | static void dns_transaction_flush_dnssec_transactions(DnsTransaction *t) { | |
53 | DnsTransaction *z; | |
54 | ||
55 | assert(t); | |
56 | ||
57 | while ((z = set_steal_first(t->dnssec_transactions))) { | |
58 | set_remove(z->notify_transactions, t); | |
59 | set_remove(z->notify_transactions_done, t); | |
60 | dns_transaction_gc(z); | |
61 | } | |
62 | } | |
63 | ||
64 | static void dns_transaction_close_connection( | |
65 | DnsTransaction *t, | |
66 | bool use_graveyard) { /* Set use_graveyard = false when you know the connection is already | |
67 | * dead, for example because you got a connection error back from the | |
68 | * kernel. In that case there's no point in keeping the fd around, | |
69 | * hence don't. */ | |
70 | int r; | |
71 | ||
72 | assert(t); | |
73 | ||
74 | if (t->stream) { | |
75 | /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */ | |
76 | LIST_REMOVE(transactions_by_stream, t->stream->transactions, t); | |
77 | ||
78 | /* Remove packet in case it's still in the queue */ | |
79 | dns_packet_unref(ordered_set_remove(t->stream->write_queue, t->sent)); | |
80 | ||
81 | t->stream = dns_stream_unref(t->stream); | |
82 | } | |
83 | ||
84 | t->dns_udp_event_source = sd_event_source_disable_unref(t->dns_udp_event_source); | |
85 | ||
86 | /* If we have a UDP socket where we sent a packet, but never received one, then add it to the socket | |
87 | * graveyard, instead of closing it right away. That way it will stick around for a moment longer, | |
88 | * and the reply we might still get from the server will be eaten up instead of resulting in an ICMP | |
89 | * port unreachable error message. */ | |
90 | ||
91 | /* Skip the graveyard stuff when we're shutting down, since that requires running event loop. | |
92 | * Note that this is also called from dns_transaction_free(). In that case, scope may be NULL. */ | |
93 | if (!t->scope || | |
94 | !t->scope->manager || | |
95 | !t->scope->manager->event || | |
96 | sd_event_get_state(t->scope->manager->event) == SD_EVENT_FINISHED) | |
97 | use_graveyard = false; | |
98 | ||
99 | if (use_graveyard && t->dns_udp_fd >= 0 && t->sent && !t->received) { | |
100 | r = manager_add_socket_to_graveyard(t->scope->manager, t->dns_udp_fd); | |
101 | if (r < 0) | |
102 | log_debug_errno(r, "Failed to add UDP socket to graveyard, closing immediately: %m"); | |
103 | else | |
104 | TAKE_FD(t->dns_udp_fd); | |
105 | } | |
106 | ||
107 | t->dns_udp_fd = safe_close(t->dns_udp_fd); | |
108 | } | |
109 | ||
110 | static void dns_transaction_stop_timeout(DnsTransaction *t) { | |
111 | assert(t); | |
112 | ||
113 | t->timeout_event_source = sd_event_source_disable_unref(t->timeout_event_source); | |
114 | } | |
115 | ||
116 | DnsTransaction* dns_transaction_free(DnsTransaction *t) { | |
117 | DnsQueryCandidate *c; | |
118 | DnsZoneItem *i; | |
119 | DnsTransaction *z; | |
120 | ||
121 | if (!t) | |
122 | return NULL; | |
123 | ||
124 | log_debug("Freeing transaction %" PRIu16 ".", t->id); | |
125 | ||
126 | dns_transaction_close_connection(t, true); | |
127 | dns_transaction_stop_timeout(t); | |
128 | ||
129 | dns_packet_unref(t->sent); | |
130 | dns_transaction_reset_answer(t); | |
131 | ||
132 | dns_server_unref(t->server); | |
133 | ||
134 | if (t->scope) { | |
135 | if (t->key) { | |
136 | DnsTransaction *first; | |
137 | ||
138 | first = hashmap_get(t->scope->transactions_by_key, t->key); | |
139 | LIST_REMOVE(transactions_by_key, first, t); | |
140 | if (first) | |
141 | hashmap_replace(t->scope->transactions_by_key, first->key, first); | |
142 | else | |
143 | hashmap_remove(t->scope->transactions_by_key, t->key); | |
144 | } | |
145 | ||
146 | LIST_REMOVE(transactions_by_scope, t->scope->transactions, t); | |
147 | ||
148 | if (t->id != 0) | |
149 | hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id)); | |
150 | } | |
151 | ||
152 | while ((c = set_steal_first(t->notify_query_candidates))) | |
153 | set_remove(c->transactions, t); | |
154 | set_free(t->notify_query_candidates); | |
155 | ||
156 | while ((c = set_steal_first(t->notify_query_candidates_done))) | |
157 | set_remove(c->transactions, t); | |
158 | set_free(t->notify_query_candidates_done); | |
159 | ||
160 | while ((i = set_steal_first(t->notify_zone_items))) | |
161 | i->probe_transaction = NULL; | |
162 | set_free(t->notify_zone_items); | |
163 | ||
164 | while ((i = set_steal_first(t->notify_zone_items_done))) | |
165 | i->probe_transaction = NULL; | |
166 | set_free(t->notify_zone_items_done); | |
167 | ||
168 | while ((z = set_steal_first(t->notify_transactions))) | |
169 | set_remove(z->dnssec_transactions, t); | |
170 | set_free(t->notify_transactions); | |
171 | ||
172 | while ((z = set_steal_first(t->notify_transactions_done))) | |
173 | set_remove(z->dnssec_transactions, t); | |
174 | set_free(t->notify_transactions_done); | |
175 | ||
176 | dns_transaction_flush_dnssec_transactions(t); | |
177 | set_free(t->dnssec_transactions); | |
178 | ||
179 | dns_answer_unref(t->validated_keys); | |
180 | dns_resource_key_unref(t->key); | |
181 | dns_packet_unref(t->bypass); | |
182 | ||
183 | return mfree(t); | |
184 | } | |
185 | ||
186 | DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free); | |
187 | ||
188 | DnsTransaction* dns_transaction_gc(DnsTransaction *t) { | |
189 | assert(t); | |
190 | ||
191 | /* Returns !NULL if we can't gc yet. */ | |
192 | ||
193 | if (t->block_gc > 0) | |
194 | return t; | |
195 | ||
196 | if (t->wait_for_answer && IN_SET(t->state, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_VALIDATING)) | |
197 | return t; | |
198 | ||
199 | if (set_isempty(t->notify_query_candidates) && | |
200 | set_isempty(t->notify_query_candidates_done) && | |
201 | set_isempty(t->notify_zone_items) && | |
202 | set_isempty(t->notify_zone_items_done) && | |
203 | set_isempty(t->notify_transactions) && | |
204 | set_isempty(t->notify_transactions_done)) | |
205 | return dns_transaction_free(t); | |
206 | ||
207 | return t; | |
208 | } | |
209 | ||
210 | static uint16_t pick_new_id(Manager *m) { | |
211 | uint16_t new_id; | |
212 | ||
213 | /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the | |
214 | * number of transactions, and it's much lower than the space of IDs. */ | |
215 | ||
216 | assert_cc(TRANSACTIONS_MAX < 0xFFFF); | |
217 | ||
218 | do | |
219 | random_bytes(&new_id, sizeof(new_id)); | |
220 | while (new_id == 0 || | |
221 | hashmap_get(m->dns_transactions, UINT_TO_PTR(new_id))); | |
222 | ||
223 | return new_id; | |
224 | } | |
225 | ||
226 | static int key_ok( | |
227 | DnsScope *scope, | |
228 | DnsResourceKey *key) { | |
229 | ||
230 | /* Don't allow looking up invalid or pseudo RRs */ | |
231 | if (!dns_type_is_valid_query(key->type)) | |
232 | return -EINVAL; | |
233 | if (dns_type_is_obsolete(key->type)) | |
234 | return -EOPNOTSUPP; | |
235 | ||
236 | /* We only support the IN class */ | |
237 | if (!IN_SET(key->class, DNS_CLASS_IN, DNS_CLASS_ANY)) | |
238 | return -EOPNOTSUPP; | |
239 | ||
240 | /* Don't allows DNSSEC RRs to be looked up via LLMNR/mDNS. They don't really make sense | |
241 | * there, and it speeds up our queries if we refuse this early */ | |
242 | if (scope->protocol != DNS_PROTOCOL_DNS && | |
243 | dns_type_is_dnssec(key->type)) | |
244 | return -EOPNOTSUPP; | |
245 | ||
246 | return 0; | |
247 | } | |
248 | ||
249 | int dns_transaction_new( | |
250 | DnsTransaction **ret, | |
251 | DnsScope *s, | |
252 | DnsResourceKey *key, | |
253 | DnsPacket *bypass, | |
254 | uint64_t query_flags) { | |
255 | ||
256 | _cleanup_(dns_transaction_freep) DnsTransaction *t = NULL; | |
257 | int r; | |
258 | ||
259 | assert(ret); | |
260 | assert(s); | |
261 | ||
262 | if (key) { | |
263 | assert(!bypass); | |
264 | ||
265 | r = key_ok(s, key); | |
266 | if (r < 0) | |
267 | return r; | |
268 | } else { | |
269 | DnsResourceKey *qk; | |
270 | assert(bypass); | |
271 | ||
272 | r = dns_packet_validate_query(bypass); | |
273 | if (r < 0) | |
274 | return r; | |
275 | ||
276 | DNS_QUESTION_FOREACH(qk, bypass->question) { | |
277 | r = key_ok(s, qk); | |
278 | if (r < 0) | |
279 | return r; | |
280 | } | |
281 | } | |
282 | ||
283 | if (hashmap_size(s->manager->dns_transactions) >= TRANSACTIONS_MAX) | |
284 | return -EBUSY; | |
285 | ||
286 | r = hashmap_ensure_allocated(&s->manager->dns_transactions, NULL); | |
287 | if (r < 0) | |
288 | return r; | |
289 | ||
290 | if (key) { | |
291 | r = hashmap_ensure_allocated(&s->transactions_by_key, &dns_resource_key_hash_ops); | |
292 | if (r < 0) | |
293 | return r; | |
294 | } | |
295 | ||
296 | t = new(DnsTransaction, 1); | |
297 | if (!t) | |
298 | return -ENOMEM; | |
299 | ||
300 | *t = (DnsTransaction) { | |
301 | .dns_udp_fd = -EBADF, | |
302 | .answer_source = _DNS_TRANSACTION_SOURCE_INVALID, | |
303 | .answer_dnssec_result = _DNSSEC_RESULT_INVALID, | |
304 | .answer_ede_rcode = _DNS_EDE_RCODE_INVALID, | |
305 | .answer_nsec_ttl = UINT32_MAX, | |
306 | .key = dns_resource_key_ref(key), | |
307 | .query_flags = query_flags, | |
308 | .bypass = dns_packet_ref(bypass), | |
309 | .current_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID, | |
310 | .clamp_feature_level_servfail = _DNS_SERVER_FEATURE_LEVEL_INVALID, | |
311 | .id = pick_new_id(s->manager), | |
312 | }; | |
313 | ||
314 | r = hashmap_put(s->manager->dns_transactions, UINT_TO_PTR(t->id), t); | |
315 | if (r < 0) { | |
316 | t->id = 0; | |
317 | return r; | |
318 | } | |
319 | ||
320 | if (t->key) { | |
321 | DnsTransaction *first; | |
322 | ||
323 | first = hashmap_get(s->transactions_by_key, t->key); | |
324 | LIST_PREPEND(transactions_by_key, first, t); | |
325 | ||
326 | r = hashmap_replace(s->transactions_by_key, first->key, first); | |
327 | if (r < 0) { | |
328 | LIST_REMOVE(transactions_by_key, first, t); | |
329 | return r; | |
330 | } | |
331 | } | |
332 | ||
333 | LIST_PREPEND(transactions_by_scope, s->transactions, t); | |
334 | t->scope = s; | |
335 | ||
336 | s->manager->n_transactions_total++; | |
337 | ||
338 | if (ret) | |
339 | *ret = t; | |
340 | ||
341 | TAKE_PTR(t); | |
342 | return 0; | |
343 | } | |
344 | ||
345 | static void dns_transaction_shuffle_id(DnsTransaction *t) { | |
346 | uint16_t new_id; | |
347 | assert(t); | |
348 | ||
349 | /* Pick a new ID for this transaction. */ | |
350 | ||
351 | new_id = pick_new_id(t->scope->manager); | |
352 | assert_se(hashmap_remove_and_put(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id), UINT_TO_PTR(new_id), t) >= 0); | |
353 | ||
354 | log_debug("Transaction %" PRIu16 " is now %" PRIu16 ".", t->id, new_id); | |
355 | t->id = new_id; | |
356 | ||
357 | /* Make sure we generate a new packet with the new ID */ | |
358 | t->sent = dns_packet_unref(t->sent); | |
359 | } | |
360 | ||
361 | static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) { | |
362 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
363 | DnsZoneItem *z; | |
364 | ||
365 | assert(t); | |
366 | assert(p); | |
367 | assert(t->scope->protocol == DNS_PROTOCOL_LLMNR); | |
368 | ||
369 | if (manager_packet_from_local_address(t->scope->manager, p) != 0) | |
370 | return; | |
371 | ||
372 | log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s got tentative packet from %s.", | |
373 | t->id, | |
374 | dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str), | |
375 | dns_protocol_to_string(t->scope->protocol), | |
376 | t->scope->link ? t->scope->link->ifname : "*", | |
377 | af_to_name_short(t->scope->family), | |
378 | IN_ADDR_TO_STRING(p->family, &p->sender)); | |
379 | ||
380 | /* RFC 4795, Section 4.1 says that the peer with the | |
381 | * lexicographically smaller IP address loses */ | |
382 | if (memcmp(&p->sender, &p->destination, FAMILY_ADDRESS_SIZE(p->family)) >= 0) { | |
383 | log_debug("Peer has lexicographically larger IP address and thus lost in the conflict."); | |
384 | return; | |
385 | } | |
386 | ||
387 | log_debug("We have the lexicographically larger IP address and thus lost in the conflict."); | |
388 | ||
389 | t->block_gc++; | |
390 | ||
391 | while ((z = set_first(t->notify_zone_items))) { | |
392 | /* First, make sure the zone item drops the reference | |
393 | * to us */ | |
394 | dns_zone_item_probe_stop(z); | |
395 | ||
396 | /* Secondly, report this as conflict, so that we might | |
397 | * look for a different hostname */ | |
398 | dns_zone_item_conflict(z); | |
399 | } | |
400 | t->block_gc--; | |
401 | ||
402 | dns_transaction_gc(t); | |
403 | } | |
404 | ||
405 | void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state) { | |
406 | DnsQueryCandidate *c; | |
407 | DnsZoneItem *z; | |
408 | DnsTransaction *d; | |
409 | const char *st; | |
410 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
411 | ||
412 | assert(t); | |
413 | assert(!DNS_TRANSACTION_IS_LIVE(state)); | |
414 | ||
415 | if (state == DNS_TRANSACTION_DNSSEC_FAILED) { | |
416 | dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str); | |
417 | ||
418 | log_struct(LOG_NOTICE, | |
419 | LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_FAILURE_STR), | |
420 | LOG_MESSAGE("DNSSEC validation failed for question %s: %s", | |
421 | key_str, dnssec_result_to_string(t->answer_dnssec_result)), | |
422 | LOG_ITEM("DNS_TRANSACTION=%" PRIu16, t->id), | |
423 | LOG_ITEM("DNS_QUESTION=%s", key_str), | |
424 | LOG_ITEM("DNSSEC_RESULT=%s", dnssec_result_to_string(t->answer_dnssec_result)), | |
425 | LOG_ITEM("DNS_SERVER=%s", strna(dns_server_string_full(t->server))), | |
426 | LOG_ITEM("DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t->server->possible_feature_level))); | |
427 | } | |
428 | ||
429 | /* Note that this call might invalidate the query. Callers | |
430 | * should hence not attempt to access the query or transaction | |
431 | * after calling this function. */ | |
432 | ||
433 | if (state == DNS_TRANSACTION_ERRNO) | |
434 | st = errno_to_name(t->answer_errno); | |
435 | else | |
436 | st = dns_transaction_state_to_string(state); | |
437 | ||
438 | log_debug("%s transaction %" PRIu16 " for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s; %s).", | |
439 | t->bypass ? "Bypass" : "Regular", | |
440 | t->id, | |
441 | dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str), | |
442 | dns_protocol_to_string(t->scope->protocol), | |
443 | t->scope->link ? t->scope->link->ifname : "*", | |
444 | af_to_name_short(t->scope->family), | |
445 | st, | |
446 | t->answer_source < 0 ? "none" : dns_transaction_source_to_string(t->answer_source), | |
447 | FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) ? "not validated" : | |
448 | (FLAGS_SET(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED) ? "authenticated" : "unsigned"), | |
449 | FLAGS_SET(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL) ? "confidential" : "non-confidential"); | |
450 | ||
451 | t->state = state; | |
452 | ||
453 | dns_transaction_close_connection(t, true); | |
454 | dns_transaction_stop_timeout(t); | |
455 | ||
456 | /* Notify all queries that are interested, but make sure the | |
457 | * transaction isn't freed while we are still looking at it */ | |
458 | t->block_gc++; | |
459 | ||
460 | SET_FOREACH_MOVE(c, t->notify_query_candidates_done, t->notify_query_candidates) | |
461 | dns_query_candidate_notify(c); | |
462 | SWAP_TWO(t->notify_query_candidates, t->notify_query_candidates_done); | |
463 | ||
464 | SET_FOREACH_MOVE(z, t->notify_zone_items_done, t->notify_zone_items) | |
465 | dns_zone_item_notify(z); | |
466 | SWAP_TWO(t->notify_zone_items, t->notify_zone_items_done); | |
467 | if (t->probing && t->state == DNS_TRANSACTION_ATTEMPTS_MAX_REACHED) | |
468 | (void) dns_scope_announce(t->scope, false); | |
469 | ||
470 | SET_FOREACH_MOVE(d, t->notify_transactions_done, t->notify_transactions) | |
471 | dns_transaction_notify(d, t); | |
472 | SWAP_TWO(t->notify_transactions, t->notify_transactions_done); | |
473 | ||
474 | t->block_gc--; | |
475 | dns_transaction_gc(t); | |
476 | } | |
477 | ||
478 | static void dns_transaction_complete_errno(DnsTransaction *t, int error) { | |
479 | assert(t); | |
480 | assert(error != 0); | |
481 | ||
482 | t->answer_errno = ABS(error); | |
483 | dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); | |
484 | } | |
485 | ||
486 | static int dns_transaction_pick_server(DnsTransaction *t) { | |
487 | DnsServer *server; | |
488 | ||
489 | assert(t); | |
490 | assert(t->scope->protocol == DNS_PROTOCOL_DNS); | |
491 | ||
492 | /* Pick a DNS server and a feature level for it. */ | |
493 | ||
494 | server = dns_scope_get_dns_server(t->scope); | |
495 | if (!server) | |
496 | return -ESRCH; | |
497 | ||
498 | /* If we changed the server invalidate the feature level clamping, as the new server might have completely | |
499 | * different properties. */ | |
500 | if (server != t->server) | |
501 | t->clamp_feature_level_servfail = _DNS_SERVER_FEATURE_LEVEL_INVALID; | |
502 | ||
503 | t->current_feature_level = dns_server_possible_feature_level(server); | |
504 | ||
505 | /* Clamp the feature level if that is requested. */ | |
506 | if (t->clamp_feature_level_servfail != _DNS_SERVER_FEATURE_LEVEL_INVALID && | |
507 | t->current_feature_level > t->clamp_feature_level_servfail) | |
508 | t->current_feature_level = t->clamp_feature_level_servfail; | |
509 | ||
510 | log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t->current_feature_level), t->id); | |
511 | ||
512 | if (server == t->server) | |
513 | return 0; | |
514 | ||
515 | dns_server_unref(t->server); | |
516 | t->server = dns_server_ref(server); | |
517 | ||
518 | t->n_picked_servers++; | |
519 | ||
520 | log_debug("Using DNS server %s for transaction %u.", strna(dns_server_string_full(t->server)), t->id); | |
521 | ||
522 | return 1; | |
523 | } | |
524 | ||
525 | static void dns_transaction_retry(DnsTransaction *t, bool next_server) { | |
526 | int r; | |
527 | ||
528 | assert(t); | |
529 | ||
530 | /* Retries the transaction as it is, possibly on a different server */ | |
531 | ||
532 | if (next_server && t->scope->protocol == DNS_PROTOCOL_DNS) | |
533 | log_debug("Retrying transaction %" PRIu16 ", after switching servers.", t->id); | |
534 | else | |
535 | log_debug("Retrying transaction %" PRIu16 ".", t->id); | |
536 | ||
537 | /* Before we try again, switch to a new server. */ | |
538 | if (next_server) | |
539 | dns_scope_next_dns_server(t->scope, t->server); | |
540 | ||
541 | r = dns_transaction_go(t); | |
542 | if (r < 0) | |
543 | dns_transaction_complete_errno(t, r); | |
544 | } | |
545 | ||
546 | static bool dns_transaction_limited_retry(DnsTransaction *t) { | |
547 | assert(t); | |
548 | ||
549 | /* If we haven't tried all different servers yet, let's try again with a different server */ | |
550 | ||
551 | if (t->n_picked_servers >= dns_scope_get_n_dns_servers(t->scope)) | |
552 | return false; | |
553 | ||
554 | dns_transaction_retry(t, /* next_server= */ true); | |
555 | return true; | |
556 | } | |
557 | ||
558 | static int dns_transaction_maybe_restart(DnsTransaction *t) { | |
559 | int r; | |
560 | ||
561 | assert(t); | |
562 | ||
563 | /* Restarts the transaction, under a new ID if the feature level of the server changed since we first | |
564 | * tried, without changing DNS server. Returns > 0 if the transaction was restarted, 0 if not. */ | |
565 | ||
566 | if (!t->server) | |
567 | return 0; | |
568 | ||
569 | if (t->current_feature_level <= dns_server_possible_feature_level(t->server)) | |
570 | return 0; | |
571 | ||
572 | /* The server's current feature level is lower than when we sent the original query. We learnt something from | |
573 | the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to | |
574 | restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include | |
575 | OPT RR or DO bit. One of these cases is documented here, for example: | |
576 | https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */ | |
577 | ||
578 | log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID."); | |
579 | dns_transaction_shuffle_id(t); | |
580 | ||
581 | r = dns_transaction_go(t); | |
582 | if (r < 0) | |
583 | return r; | |
584 | ||
585 | return 1; | |
586 | } | |
587 | ||
588 | static void on_transaction_stream_error(DnsTransaction *t, int error) { | |
589 | assert(t); | |
590 | ||
591 | dns_transaction_close_connection(t, true); | |
592 | ||
593 | if (ERRNO_IS_DISCONNECT(error)) { | |
594 | if (t->scope->protocol == DNS_PROTOCOL_LLMNR) { | |
595 | /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the | |
596 | * question on this scope. */ | |
597 | dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND); | |
598 | return; | |
599 | } | |
600 | ||
601 | dns_transaction_retry(t, true); | |
602 | return; | |
603 | } | |
604 | if (error != 0) | |
605 | dns_transaction_complete_errno(t, error); | |
606 | } | |
607 | ||
608 | static int dns_transaction_on_stream_packet(DnsTransaction *t, DnsStream *s, DnsPacket *p) { | |
609 | bool encrypted; | |
610 | ||
611 | assert(t); | |
612 | assert(s); | |
613 | assert(p); | |
614 | ||
615 | encrypted = s->encrypted; | |
616 | ||
617 | dns_transaction_close_connection(t, true); | |
618 | ||
619 | if (dns_packet_validate_reply(p) <= 0) { | |
620 | log_debug("Invalid TCP reply packet."); | |
621 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
622 | return 0; | |
623 | } | |
624 | ||
625 | dns_scope_check_conflicts(t->scope, p); | |
626 | ||
627 | t->block_gc++; | |
628 | dns_transaction_process_reply(t, p, encrypted); | |
629 | t->block_gc--; | |
630 | ||
631 | /* If the response wasn't useful, then complete the transition | |
632 | * now. After all, we are the worst feature set now with TCP | |
633 | * sockets, and there's really no point in retrying. */ | |
634 | if (t->state == DNS_TRANSACTION_PENDING) | |
635 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
636 | else | |
637 | dns_transaction_gc(t); | |
638 | ||
639 | return 0; | |
640 | } | |
641 | ||
642 | static int on_stream_complete(DnsStream *s, int error) { | |
643 | assert(s); | |
644 | ||
645 | if (ERRNO_IS_DISCONNECT(error) && s->protocol != DNS_PROTOCOL_LLMNR) { | |
646 | log_debug_errno(error, "Connection failure for DNS TCP stream: %m"); | |
647 | ||
648 | if (error != ECONNRESET && s->transactions) { | |
649 | DnsTransaction *t; | |
650 | ||
651 | t = s->transactions; | |
652 | dns_server_packet_lost(t->server, IPPROTO_TCP, t->current_feature_level); | |
653 | } | |
654 | } | |
655 | ||
656 | if (error != 0) { | |
657 | /* First, detach the stream from the server. Otherwise, transactions attached to this stream | |
658 | * may be restarted by on_transaction_stream_error() below with this stream. */ | |
659 | dns_stream_detach(s); | |
660 | ||
661 | /* Do not use LIST_FOREACH() here, as | |
662 | * on_transaction_stream_error() | |
663 | * -> dns_transaction_complete_errno() | |
664 | * -> dns_transaction_free() | |
665 | * may free multiple transactions in the list. */ | |
666 | DnsTransaction *t; | |
667 | while ((t = s->transactions)) | |
668 | on_transaction_stream_error(t, error); | |
669 | } | |
670 | ||
671 | return 0; | |
672 | } | |
673 | ||
674 | static int on_stream_packet(DnsStream *s, DnsPacket *p) { | |
675 | DnsTransaction *t; | |
676 | ||
677 | assert(s); | |
678 | assert(s->manager); | |
679 | assert(p); | |
680 | ||
681 | t = hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p))); | |
682 | if (t && t->stream == s) /* Validate that the stream we got this on actually is the stream the | |
683 | * transaction was using. */ | |
684 | return dns_transaction_on_stream_packet(t, s, p); | |
685 | ||
686 | /* Ignore incorrect transaction id as an old transaction can have been canceled. */ | |
687 | log_debug("Received unexpected TCP reply packet with id %" PRIu16 ", ignoring.", DNS_PACKET_ID(p)); | |
688 | return 0; | |
689 | } | |
690 | ||
691 | static uint16_t dns_transaction_port(DnsTransaction *t) { | |
692 | assert(t); | |
693 | ||
694 | if (t->server->port > 0) | |
695 | return t->server->port; | |
696 | ||
697 | return DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) ? 853 : 53; | |
698 | } | |
699 | ||
700 | static int dns_transaction_emit_tcp(DnsTransaction *t) { | |
701 | usec_t stream_timeout_usec = DNS_STREAM_DEFAULT_TIMEOUT_USEC; | |
702 | _cleanup_(dns_stream_unrefp) DnsStream *s = NULL; | |
703 | _cleanup_close_ int fd = -EBADF; | |
704 | union sockaddr_union sa; | |
705 | DnsStreamType type; | |
706 | int r; | |
707 | ||
708 | assert(t); | |
709 | assert(t->sent); | |
710 | ||
711 | dns_transaction_close_connection(t, true); | |
712 | ||
713 | switch (t->scope->protocol) { | |
714 | ||
715 | case DNS_PROTOCOL_DNS: | |
716 | r = dns_transaction_pick_server(t); | |
717 | if (r < 0) | |
718 | return r; | |
719 | ||
720 | if (manager_server_is_stub(t->scope->manager, t->server)) | |
721 | return -ELOOP; | |
722 | ||
723 | if (!t->bypass) { | |
724 | if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(dns_transaction_key(t)->type)) | |
725 | return -EOPNOTSUPP; | |
726 | ||
727 | r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level); | |
728 | if (r < 0) | |
729 | return r; | |
730 | } | |
731 | ||
732 | if (t->server->stream && (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) == t->server->stream->encrypted)) | |
733 | s = dns_stream_ref(t->server->stream); | |
734 | else | |
735 | fd = dns_scope_socket_tcp(t->scope, AF_UNSPEC, NULL, t->server, dns_transaction_port(t), &sa); | |
736 | ||
737 | /* Lower timeout in DNS-over-TLS opportunistic mode. In environments where DoT is blocked | |
738 | * without ICMP response overly long delays when contacting DoT servers are nasty, in | |
739 | * particular if multiple DNS servers are defined which we try in turn and all are | |
740 | * blocked. Hence, substantially lower the timeout in that case. */ | |
741 | if (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) && | |
742 | dns_server_get_dns_over_tls_mode(t->server) == DNS_OVER_TLS_OPPORTUNISTIC) | |
743 | stream_timeout_usec = DNS_STREAM_OPPORTUNISTIC_TLS_TIMEOUT_USEC; | |
744 | ||
745 | type = DNS_STREAM_LOOKUP; | |
746 | break; | |
747 | ||
748 | case DNS_PROTOCOL_LLMNR: | |
749 | /* When we already received a reply to this (but it was truncated), send to its sender address */ | |
750 | if (t->received) | |
751 | fd = dns_scope_socket_tcp(t->scope, t->received->family, &t->received->sender, NULL, t->received->sender_port, &sa); | |
752 | else { | |
753 | union in_addr_union address; | |
754 | int family = AF_UNSPEC; | |
755 | ||
756 | /* Otherwise, try to talk to the owner of a | |
757 | * the IP address, in case this is a reverse | |
758 | * PTR lookup */ | |
759 | ||
760 | r = dns_name_address(dns_resource_key_name(dns_transaction_key(t)), &family, &address); | |
761 | if (r < 0) | |
762 | return r; | |
763 | if (r == 0) | |
764 | return -EINVAL; | |
765 | if (family != t->scope->family) | |
766 | return -ESRCH; | |
767 | ||
768 | fd = dns_scope_socket_tcp(t->scope, family, &address, NULL, LLMNR_PORT, &sa); | |
769 | } | |
770 | ||
771 | type = DNS_STREAM_LLMNR_SEND; | |
772 | break; | |
773 | ||
774 | default: | |
775 | return -EAFNOSUPPORT; | |
776 | } | |
777 | ||
778 | if (!s) { | |
779 | if (fd < 0) | |
780 | return fd; | |
781 | ||
782 | r = dns_stream_new(t->scope->manager, &s, type, t->scope->protocol, fd, &sa, | |
783 | on_stream_packet, on_stream_complete, stream_timeout_usec); | |
784 | if (r < 0) | |
785 | return r; | |
786 | ||
787 | fd = -EBADF; | |
788 | ||
789 | #if ENABLE_DNS_OVER_TLS | |
790 | if (t->scope->protocol == DNS_PROTOCOL_DNS && | |
791 | DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level)) { | |
792 | ||
793 | assert(t->server); | |
794 | r = dnstls_stream_connect_tls(s, t->server); | |
795 | if (r < 0) | |
796 | return r; | |
797 | } | |
798 | #endif | |
799 | ||
800 | if (t->server) { | |
801 | dns_server_unref_stream(t->server); | |
802 | s->server = dns_server_ref(t->server); | |
803 | t->server->stream = dns_stream_ref(s); | |
804 | } | |
805 | ||
806 | /* The interface index is difficult to determine if we are | |
807 | * connecting to the local host, hence fill this in right away | |
808 | * instead of determining it from the socket */ | |
809 | s->ifindex = dns_scope_ifindex(t->scope); | |
810 | } | |
811 | ||
812 | t->stream = TAKE_PTR(s); | |
813 | LIST_PREPEND(transactions_by_stream, t->stream->transactions, t); | |
814 | ||
815 | r = dns_stream_write_packet(t->stream, t->sent); | |
816 | if (r < 0) { | |
817 | dns_transaction_close_connection(t, /* use_graveyard= */ false); | |
818 | return r; | |
819 | } | |
820 | ||
821 | dns_transaction_reset_answer(t); | |
822 | ||
823 | t->tried_stream = true; | |
824 | ||
825 | return 0; | |
826 | } | |
827 | ||
828 | static void dns_transaction_cache_answer(DnsTransaction *t) { | |
829 | assert(t); | |
830 | ||
831 | /* For mDNS we cache whenever we get the packet, rather than | |
832 | * in each transaction. */ | |
833 | if (!IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR)) | |
834 | return; | |
835 | ||
836 | /* Caching disabled? */ | |
837 | if (t->scope->manager->enable_cache == DNS_CACHE_MODE_NO) | |
838 | return; | |
839 | ||
840 | /* If validation is turned off for this transaction, but DNSSEC is on, then let's not cache this */ | |
841 | if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) && t->scope->dnssec_mode != DNSSEC_NO) | |
842 | return; | |
843 | ||
844 | /* Packet from localhost? */ | |
845 | if (!t->scope->manager->cache_from_localhost && | |
846 | in_addr_is_localhost(t->received->family, &t->received->sender) != 0) | |
847 | return; | |
848 | ||
849 | dns_cache_put(&t->scope->cache, | |
850 | t->scope->manager->enable_cache, | |
851 | t->scope->protocol, | |
852 | dns_transaction_key(t), | |
853 | t->answer_rcode, | |
854 | t->answer, | |
855 | /* If neither DO nor EDE is set, the full packet isn't useful to cache */ | |
856 | dns_packet_do(t->received) || t->answer_ede_rcode > 0 || t->answer_ede_msg ? t->received : NULL, | |
857 | t->answer_query_flags, | |
858 | t->answer_dnssec_result, | |
859 | t->answer_nsec_ttl, | |
860 | t->received->family, | |
861 | &t->received->sender, | |
862 | t->scope->manager->stale_retention_usec); | |
863 | } | |
864 | ||
865 | static bool dns_transaction_dnssec_is_live(DnsTransaction *t) { | |
866 | DnsTransaction *dt; | |
867 | ||
868 | assert(t); | |
869 | ||
870 | SET_FOREACH(dt, t->dnssec_transactions) | |
871 | if (DNS_TRANSACTION_IS_LIVE(dt->state)) | |
872 | return true; | |
873 | ||
874 | return false; | |
875 | } | |
876 | ||
877 | static int dns_transaction_dnssec_ready(DnsTransaction *t) { | |
878 | DnsTransaction *dt; | |
879 | int r; | |
880 | ||
881 | assert(t); | |
882 | ||
883 | /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still | |
884 | * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */ | |
885 | ||
886 | SET_FOREACH(dt, t->dnssec_transactions) { | |
887 | ||
888 | switch (dt->state) { | |
889 | ||
890 | case DNS_TRANSACTION_NULL: | |
891 | case DNS_TRANSACTION_PENDING: | |
892 | case DNS_TRANSACTION_VALIDATING: | |
893 | /* Still ongoing */ | |
894 | return 0; | |
895 | ||
896 | case DNS_TRANSACTION_RCODE_FAILURE: | |
897 | if (!IN_SET(dt->answer_rcode, DNS_RCODE_NXDOMAIN, DNS_RCODE_SERVFAIL)) { | |
898 | log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", FORMAT_DNS_RCODE(dt->answer_rcode)); | |
899 | goto fail; | |
900 | } | |
901 | ||
902 | /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers | |
903 | * erroneously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS | |
904 | * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar | |
905 | * RRs to make unsigned proofs. */ | |
906 | ||
907 | case DNS_TRANSACTION_SUCCESS: | |
908 | /* All good. */ | |
909 | break; | |
910 | ||
911 | case DNS_TRANSACTION_DNSSEC_FAILED: | |
912 | /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC | |
913 | * validation result */ | |
914 | ||
915 | log_debug("Auxiliary DNSSEC RR query failed validation: %s%s%s%s%s%s", | |
916 | dnssec_result_to_string(dt->answer_dnssec_result), | |
917 | dt->answer_ede_rcode >= 0 ? " (" : "", | |
918 | dt->answer_ede_rcode >= 0 ? FORMAT_DNS_EDE_RCODE(dt->answer_ede_rcode) : "", | |
919 | (dt->answer_ede_rcode >= 0 && !isempty(dt->answer_ede_msg)) ? ": " : "", | |
920 | dt->answer_ede_rcode >= 0 ? strempty(dt->answer_ede_msg) : "", | |
921 | dt->answer_ede_rcode >= 0 ? ")" : ""); | |
922 | ||
923 | /* Copy error code over */ | |
924 | t->answer_dnssec_result = dt->answer_dnssec_result; | |
925 | t->answer_ede_rcode = dt->answer_ede_rcode; | |
926 | r = free_and_strdup(&t->answer_ede_msg, dt->answer_ede_msg); | |
927 | if (r < 0) | |
928 | log_oom_debug(); | |
929 | ||
930 | /* The answer would normally be replaced by the validated subset, but at this point | |
931 | * we aren't going to bother validating the rest, so just drop it. */ | |
932 | t->answer = dns_answer_unref(t->answer); | |
933 | ||
934 | dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); | |
935 | return 0; | |
936 | ||
937 | default: | |
938 | log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt->state)); | |
939 | goto fail; | |
940 | } | |
941 | } | |
942 | ||
943 | /* All is ready, we can go and validate */ | |
944 | return 1; | |
945 | ||
946 | fail: | |
947 | /* Some auxiliary DNSSEC transaction failed for some reason. Maybe we learned something about the | |
948 | * server due to this failure, and the feature level is now different? Let's see and restart the | |
949 | * transaction if so. If not, let's propagate the auxiliary failure. | |
950 | * | |
951 | * This is particularly relevant if an auxiliary request figured out that DNSSEC doesn't work, and we | |
952 | * are in permissive DNSSEC mode, and thus should restart things without DNSSEC magic. */ | |
953 | r = dns_transaction_maybe_restart(t); | |
954 | if (r < 0) | |
955 | return r; | |
956 | if (r > 0) | |
957 | return 0; /* don't validate just yet, we restarted things */ | |
958 | ||
959 | t->answer_dnssec_result = DNSSEC_FAILED_AUXILIARY; | |
960 | dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); | |
961 | return 0; | |
962 | } | |
963 | ||
964 | static void dns_transaction_process_dnssec(DnsTransaction *t) { | |
965 | int r; | |
966 | ||
967 | assert(t); | |
968 | ||
969 | /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */ | |
970 | r = dns_transaction_dnssec_ready(t); | |
971 | if (r < 0) | |
972 | goto fail; | |
973 | if (r == 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */ | |
974 | return; | |
975 | ||
976 | /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better | |
977 | * restart the lookup immediately. */ | |
978 | r = dns_transaction_maybe_restart(t); | |
979 | if (r < 0) | |
980 | goto fail; | |
981 | if (r > 0) /* Transaction got restarted... */ | |
982 | return; | |
983 | ||
984 | /* All our auxiliary DNSSEC transactions are complete now. Try | |
985 | * to validate our RRset now. */ | |
986 | r = dns_transaction_validate_dnssec(t); | |
987 | if (r == -EBADMSG) { | |
988 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
989 | return; | |
990 | } | |
991 | if (r < 0) | |
992 | goto fail; | |
993 | ||
994 | if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER && | |
995 | t->scope->dnssec_mode == DNSSEC_YES) { | |
996 | ||
997 | /* We are not in automatic downgrade mode, and the server is bad. Let's try a different server, maybe | |
998 | * that works. */ | |
999 | ||
1000 | if (dns_transaction_limited_retry(t)) | |
1001 | return; | |
1002 | ||
1003 | /* OK, let's give up, apparently all servers we tried didn't work. */ | |
1004 | dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); | |
1005 | return; | |
1006 | } | |
1007 | ||
1008 | if (!IN_SET(t->answer_dnssec_result, | |
1009 | _DNSSEC_RESULT_INVALID, /* No DNSSEC validation enabled */ | |
1010 | DNSSEC_VALIDATED, /* Answer is signed and validated successfully */ | |
1011 | DNSSEC_UNSIGNED, /* Answer is right-fully unsigned */ | |
1012 | DNSSEC_INCOMPATIBLE_SERVER)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */ | |
1013 | dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); | |
1014 | return; | |
1015 | } | |
1016 | ||
1017 | if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER) | |
1018 | dns_server_warn_downgrade(t->server); | |
1019 | ||
1020 | dns_transaction_cache_answer(t); | |
1021 | ||
1022 | if (t->answer_rcode == DNS_RCODE_SUCCESS) | |
1023 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
1024 | else | |
1025 | dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE); | |
1026 | ||
1027 | return; | |
1028 | ||
1029 | fail: | |
1030 | dns_transaction_complete_errno(t, r); | |
1031 | } | |
1032 | ||
1033 | static int dns_transaction_has_positive_answer(DnsTransaction *t, DnsAnswerFlags *flags) { | |
1034 | int r; | |
1035 | ||
1036 | assert(t); | |
1037 | ||
1038 | /* Checks whether the answer is positive, i.e. either a direct | |
1039 | * answer to the question, or a CNAME/DNAME for it */ | |
1040 | ||
1041 | r = dns_answer_match_key(t->answer, dns_transaction_key(t), flags); | |
1042 | if (r != 0) | |
1043 | return r; | |
1044 | ||
1045 | r = dns_answer_find_cname_or_dname(t->answer, dns_transaction_key(t), NULL, flags); | |
1046 | if (r != 0) | |
1047 | return r; | |
1048 | ||
1049 | return false; | |
1050 | } | |
1051 | ||
1052 | static int dns_transaction_fix_rcode(DnsTransaction *t) { | |
1053 | int r; | |
1054 | ||
1055 | assert(t); | |
1056 | ||
1057 | /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the | |
1058 | * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a | |
1059 | * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first | |
1060 | * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when | |
1061 | * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle | |
1062 | * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a | |
1063 | * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server | |
1064 | * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an | |
1065 | * incomplete CNAME/DNAME chain. | |
1066 | * | |
1067 | * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS, | |
1068 | * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new | |
1069 | * lookup. */ | |
1070 | ||
1071 | if (t->answer_rcode != DNS_RCODE_NXDOMAIN) | |
1072 | return 0; | |
1073 | ||
1074 | r = dns_transaction_has_positive_answer(t, NULL); | |
1075 | if (r <= 0) | |
1076 | return r; | |
1077 | ||
1078 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
1079 | return 0; | |
1080 | } | |
1081 | ||
1082 | void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p, bool encrypted) { | |
1083 | bool retry_with_tcp = false; | |
1084 | int r; | |
1085 | ||
1086 | assert(t); | |
1087 | assert(p); | |
1088 | assert(t->scope); | |
1089 | assert(t->scope->manager); | |
1090 | ||
1091 | if (t->state != DNS_TRANSACTION_PENDING) | |
1092 | return; | |
1093 | ||
1094 | /* Increment the total failure counter only when it is the first attempt at querying and the upstream | |
1095 | * server returns a failure response code. This ensures a more accurate count of the number of queries | |
1096 | * that received a failure response code, as it doesn't consider retries. */ | |
1097 | ||
1098 | if (t->n_attempts == 1 && !IN_SET(dns_packet_rcode(p), DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN)) | |
1099 | t->scope->manager->n_failure_responses_total++; | |
1100 | ||
1101 | /* Note that this call might invalidate the query. Callers | |
1102 | * should hence not attempt to access the query or transaction | |
1103 | * after calling this function. */ | |
1104 | ||
1105 | log_debug("Processing incoming packet of size %zu on transaction %" PRIu16" (rcode=%s).", | |
1106 | p->size, | |
1107 | t->id, FORMAT_DNS_RCODE(dns_packet_rcode(p))); | |
1108 | ||
1109 | switch (t->scope->protocol) { | |
1110 | ||
1111 | case DNS_PROTOCOL_LLMNR: | |
1112 | /* For LLMNR we will not accept any packets from other interfaces */ | |
1113 | ||
1114 | if (p->ifindex != dns_scope_ifindex(t->scope)) | |
1115 | return; | |
1116 | ||
1117 | if (p->family != t->scope->family) | |
1118 | return; | |
1119 | ||
1120 | /* Tentative packets are not full responses but still | |
1121 | * useful for identifying uniqueness conflicts during | |
1122 | * probing. */ | |
1123 | if (DNS_PACKET_LLMNR_T(p)) { | |
1124 | dns_transaction_tentative(t, p); | |
1125 | return; | |
1126 | } | |
1127 | ||
1128 | break; | |
1129 | ||
1130 | case DNS_PROTOCOL_MDNS: | |
1131 | /* For mDNS we will not accept any packets from other interfaces */ | |
1132 | ||
1133 | if (p->ifindex != dns_scope_ifindex(t->scope)) | |
1134 | return; | |
1135 | ||
1136 | if (p->family != t->scope->family) | |
1137 | return; | |
1138 | ||
1139 | break; | |
1140 | ||
1141 | case DNS_PROTOCOL_DNS: | |
1142 | /* Note that we do not need to verify the | |
1143 | * addresses/port numbers of incoming traffic, as we | |
1144 | * invoked connect() on our UDP socket in which case | |
1145 | * the kernel already does the needed verification for | |
1146 | * us. */ | |
1147 | break; | |
1148 | ||
1149 | default: | |
1150 | assert_not_reached(); | |
1151 | } | |
1152 | ||
1153 | if (t->received != p) | |
1154 | DNS_PACKET_REPLACE(t->received, dns_packet_ref(p)); | |
1155 | ||
1156 | t->answer_source = DNS_TRANSACTION_NETWORK; | |
1157 | ||
1158 | if (p->ipproto == IPPROTO_TCP) { | |
1159 | if (DNS_PACKET_TC(p)) { | |
1160 | /* Truncated via TCP? Somebody must be fucking with us */ | |
1161 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
1162 | return; | |
1163 | } | |
1164 | ||
1165 | if (DNS_PACKET_ID(p) != t->id) { | |
1166 | /* Not the reply to our query? Somebody must be fucking with us */ | |
1167 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
1168 | return; | |
1169 | } | |
1170 | } | |
1171 | ||
1172 | if (DNS_PACKET_TC(p)) { | |
1173 | ||
1174 | /* Truncated packets for mDNS are not allowed. Give up immediately. */ | |
1175 | if (t->scope->protocol == DNS_PROTOCOL_MDNS) { | |
1176 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
1177 | return; | |
1178 | } | |
1179 | ||
1180 | /* Response was truncated, let's try again with good old TCP */ | |
1181 | log_debug("Reply truncated, retrying via TCP."); | |
1182 | retry_with_tcp = true; | |
1183 | ||
1184 | } else if (t->scope->protocol == DNS_PROTOCOL_DNS && | |
1185 | DNS_PACKET_IS_FRAGMENTED(p)) { | |
1186 | ||
1187 | /* Report the fragment size, so that we downgrade from LARGE to regular EDNS0 if needed */ | |
1188 | if (t->server) | |
1189 | dns_server_packet_udp_fragmented(t->server, dns_packet_size_unfragmented(p)); | |
1190 | ||
1191 | if (t->current_feature_level > DNS_SERVER_FEATURE_LEVEL_UDP) { | |
1192 | /* Packet was fragmented. Let's retry with TCP to avoid fragmentation attack | |
1193 | * issues. (We don't do that on the lowest feature level however, since crappy DNS | |
1194 | * servers often do not implement TCP, hence falling back to TCP on fragmentation is | |
1195 | * counter-productive there.) */ | |
1196 | ||
1197 | log_debug("Reply fragmented, retrying via TCP. (Largest fragment size: %zu; Datagram size: %zu)", | |
1198 | p->fragsize, p->size); | |
1199 | retry_with_tcp = true; | |
1200 | } | |
1201 | } | |
1202 | ||
1203 | if (retry_with_tcp) { | |
1204 | r = dns_transaction_emit_tcp(t); | |
1205 | if (r == -ESRCH) { | |
1206 | /* No servers found? Damn! */ | |
1207 | dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS); | |
1208 | return; | |
1209 | } | |
1210 | if (r == -EOPNOTSUPP) { | |
1211 | /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */ | |
1212 | dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED); | |
1213 | return; | |
1214 | } | |
1215 | if (r < 0) { | |
1216 | /* On LLMNR, if we cannot connect to the host, | |
1217 | * we immediately give up */ | |
1218 | if (t->scope->protocol != DNS_PROTOCOL_DNS) | |
1219 | goto fail; | |
1220 | ||
1221 | /* On DNS, couldn't send? Try immediately again, with a new server */ | |
1222 | if (dns_transaction_limited_retry(t)) | |
1223 | return; | |
1224 | ||
1225 | /* No new server to try, give up */ | |
1226 | dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED); | |
1227 | } | |
1228 | ||
1229 | return; | |
1230 | } | |
1231 | ||
1232 | /* After the superficial checks, actually parse the message. */ | |
1233 | r = dns_packet_extract(p); | |
1234 | if (r < 0) { | |
1235 | if (t->server) { | |
1236 | dns_server_packet_invalid(t->server, t->current_feature_level); | |
1237 | ||
1238 | r = dns_transaction_maybe_restart(t); | |
1239 | if (r < 0) | |
1240 | goto fail; | |
1241 | if (r > 0) /* Transaction got restarted... */ | |
1242 | return; | |
1243 | } | |
1244 | ||
1245 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
1246 | return; | |
1247 | } | |
1248 | ||
1249 | switch (t->scope->protocol) { | |
1250 | ||
1251 | case DNS_PROTOCOL_DNS: { | |
1252 | assert(t->server); | |
1253 | ||
1254 | (void) dns_packet_ede_rcode(p, &t->answer_ede_rcode, &t->answer_ede_msg); | |
1255 | ||
1256 | if (!t->bypass && | |
1257 | IN_SET(dns_packet_rcode(p), DNS_RCODE_FORMERR, DNS_RCODE_SERVFAIL, DNS_RCODE_NOTIMP)) { | |
1258 | /* If the server has replied with detailed error data, using a degraded feature set | |
1259 | * will likely not help anyone. Examine the detailed error to determine the best | |
1260 | * course of action. */ | |
1261 | if (t->answer_ede_rcode >= 0 && dns_packet_rcode(p) == DNS_RCODE_SERVFAIL) { | |
1262 | /* These codes are related to DNSSEC configuration errors. If accurate, | |
1263 | * this is the domain operator's problem, and retrying won't help. */ | |
1264 | if (dns_ede_rcode_is_dnssec(t->answer_ede_rcode)) { | |
1265 | log_debug("Server returned error: %s (%s%s%s). Lookup failed.", | |
1266 | FORMAT_DNS_RCODE(dns_packet_rcode(p)), | |
1267 | FORMAT_DNS_EDE_RCODE(t->answer_ede_rcode), | |
1268 | isempty(t->answer_ede_msg) ? "" : ": ", | |
1269 | strempty(t->answer_ede_msg)); | |
1270 | ||
1271 | t->answer_dnssec_result = DNSSEC_UPSTREAM_FAILURE; | |
1272 | dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); | |
1273 | return; | |
1274 | } | |
1275 | ||
1276 | /* These codes probably indicate a transient error. Let's try again. */ | |
1277 | if (t->answer_ede_rcode == DNS_EDE_RCODE_NOT_READY) { | |
1278 | log_debug("Server returned error: %s (%s%s%s), retrying transaction.", | |
1279 | FORMAT_DNS_RCODE(dns_packet_rcode(p)), | |
1280 | FORMAT_DNS_EDE_RCODE(t->answer_ede_rcode), | |
1281 | isempty(t->answer_ede_msg) ? "" : ": ", | |
1282 | strempty(t->answer_ede_msg)); | |
1283 | dns_transaction_retry(t, false); | |
1284 | return; | |
1285 | } | |
1286 | ||
1287 | /* OK, the query failed, but we still shouldn't degrade the feature set for | |
1288 | * this server. */ | |
1289 | log_debug("Server returned error: %s (%s%s%s)", | |
1290 | FORMAT_DNS_RCODE(dns_packet_rcode(p)), | |
1291 | FORMAT_DNS_EDE_RCODE(t->answer_ede_rcode), | |
1292 | isempty(t->answer_ede_msg) ? "" : ": ", | |
1293 | strempty(t->answer_ede_msg)); | |
1294 | break; | |
1295 | } | |
1296 | ||
1297 | /* Request failed, immediately try again with reduced features */ | |
1298 | ||
1299 | if (t->current_feature_level <= DNS_SERVER_FEATURE_LEVEL_UDP) { | |
1300 | ||
1301 | /* This was already at UDP feature level? If so, it doesn't make sense to downgrade | |
1302 | * this transaction anymore, but let's see if it might make sense to send the request | |
1303 | * to a different DNS server instead. If not let's process the response, and accept the | |
1304 | * rcode. Note that we don't retry on TCP, since that's a suitable way to mitigate | |
1305 | * packet loss, but is not going to give us better rcodes should we actually have | |
1306 | * managed to get them already at UDP level. */ | |
1307 | ||
1308 | if (dns_transaction_limited_retry(t)) | |
1309 | return; | |
1310 | ||
1311 | /* Give up, accept the rcode */ | |
1312 | log_debug("Server returned error: %s", FORMAT_DNS_RCODE(dns_packet_rcode(p))); | |
1313 | break; | |
1314 | } | |
1315 | ||
1316 | /* SERVFAIL can happen for many reasons and may be transient. | |
1317 | * To avoid unnecessary downgrades retry once with the initial level. | |
1318 | * Check for clamp_feature_level_servfail having an invalid value as a sign that this is the | |
1319 | * first attempt to downgrade. If so, clamp to the current value so that the transaction | |
1320 | * is retried without actually downgrading. If the next try also fails we will downgrade by | |
1321 | * hitting the else branch below. */ | |
1322 | if (dns_packet_rcode(p) == DNS_RCODE_SERVFAIL && | |
1323 | t->clamp_feature_level_servfail < 0) { | |
1324 | t->clamp_feature_level_servfail = t->current_feature_level; | |
1325 | log_debug("Server returned error %s, retrying transaction.", | |
1326 | FORMAT_DNS_RCODE(dns_packet_rcode(p))); | |
1327 | } else { | |
1328 | /* Reduce this feature level by one and try again. */ | |
1329 | switch (t->current_feature_level) { | |
1330 | case DNS_SERVER_FEATURE_LEVEL_TLS_DO: | |
1331 | t->clamp_feature_level_servfail = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN; | |
1332 | break; | |
1333 | case DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN + 1: | |
1334 | /* Skip plain TLS when TLS is not supported */ | |
1335 | t->clamp_feature_level_servfail = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN - 1; | |
1336 | break; | |
1337 | default: | |
1338 | t->clamp_feature_level_servfail = t->current_feature_level - 1; | |
1339 | } | |
1340 | ||
1341 | log_debug("Server returned error %s, retrying transaction with reduced feature level %s.", | |
1342 | FORMAT_DNS_RCODE(dns_packet_rcode(p)), | |
1343 | dns_server_feature_level_to_string(t->clamp_feature_level_servfail)); | |
1344 | } | |
1345 | ||
1346 | dns_transaction_retry(t, false /* use the same server */); | |
1347 | return; | |
1348 | } | |
1349 | ||
1350 | if (dns_packet_rcode(p) == DNS_RCODE_REFUSED) { | |
1351 | /* This server refused our request? If so, try again, use a different server */ | |
1352 | if (t->answer_ede_rcode >= 0) | |
1353 | log_debug("Server returned REFUSED (%s), switching servers, and retrying.", | |
1354 | FORMAT_DNS_EDE_RCODE(t->answer_ede_rcode)); | |
1355 | else | |
1356 | log_debug("Server returned REFUSED, switching servers, and retrying."); | |
1357 | ||
1358 | if (dns_transaction_limited_retry(t)) | |
1359 | return; | |
1360 | ||
1361 | break; | |
1362 | } | |
1363 | ||
1364 | if (DNS_PACKET_TC(p)) | |
1365 | dns_server_packet_truncated(t->server, t->current_feature_level); | |
1366 | ||
1367 | break; | |
1368 | } | |
1369 | ||
1370 | case DNS_PROTOCOL_LLMNR: | |
1371 | case DNS_PROTOCOL_MDNS: | |
1372 | dns_scope_packet_received(t->scope, p->timestamp - t->start_usec); | |
1373 | break; | |
1374 | ||
1375 | default: | |
1376 | assert_not_reached(); | |
1377 | } | |
1378 | ||
1379 | if (t->server) { | |
1380 | /* Report that we successfully received a valid packet with a good rcode after we initially got a bad | |
1381 | * rcode and subsequently downgraded the protocol */ | |
1382 | ||
1383 | if (IN_SET(dns_packet_rcode(p), DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN) && | |
1384 | t->clamp_feature_level_servfail != _DNS_SERVER_FEATURE_LEVEL_INVALID) | |
1385 | dns_server_packet_rcode_downgrade(t->server, t->clamp_feature_level_servfail); | |
1386 | ||
1387 | /* Report that the OPT RR was missing */ | |
1388 | if (!p->opt) | |
1389 | dns_server_packet_bad_opt(t->server, t->current_feature_level); | |
1390 | ||
1391 | /* Report that the server didn't copy our query DO bit from request to response */ | |
1392 | if (dns_packet_do(t->sent) && !dns_packet_do(t->received)) | |
1393 | dns_server_packet_do_off(t->server, t->current_feature_level); | |
1394 | ||
1395 | /* Report that we successfully received a packet. We keep track of the largest packet | |
1396 | * size/fragment size we got. Which is useful for announcing the EDNS(0) packet size we can | |
1397 | * receive to our server. */ | |
1398 | dns_server_packet_received(t->server, p->ipproto, t->current_feature_level, dns_packet_size_unfragmented(p)); | |
1399 | } | |
1400 | ||
1401 | /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */ | |
1402 | r = dns_transaction_maybe_restart(t); | |
1403 | if (r < 0) | |
1404 | goto fail; | |
1405 | if (r > 0) /* Transaction got restarted... */ | |
1406 | return; | |
1407 | ||
1408 | /* When dealing with protocols other than mDNS only consider responses with equivalent query section | |
1409 | * to the request. For mDNS this check doesn't make sense, because the section 6 of RFC6762 states | |
1410 | * that "Multicast DNS responses MUST NOT contain any questions in the Question Section". */ | |
1411 | if (t->scope->protocol != DNS_PROTOCOL_MDNS) { | |
1412 | r = dns_packet_is_reply_for(p, dns_transaction_key(t)); | |
1413 | if (r < 0) | |
1414 | goto fail; | |
1415 | if (r == 0) { | |
1416 | dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); | |
1417 | return; | |
1418 | } | |
1419 | } | |
1420 | ||
1421 | /* Install the answer as answer to the transaction. We ref the answer twice here: the main `answer` | |
1422 | * field is later replaced by the DNSSEC validated subset. The 'answer_auxiliary' field carries the | |
1423 | * original complete record set, including RRSIG and friends. We use this when passing data to | |
1424 | * clients that ask for DNSSEC metadata. */ | |
1425 | DNS_ANSWER_REPLACE(t->answer, dns_answer_ref(p->answer)); | |
1426 | t->answer_rcode = dns_packet_rcode(p); | |
1427 | t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; | |
1428 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); | |
1429 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL, encrypted); | |
1430 | ||
1431 | r = dns_transaction_fix_rcode(t); | |
1432 | if (r < 0) | |
1433 | goto fail; | |
1434 | ||
1435 | /* Block GC while starting requests for additional DNSSEC RRs */ | |
1436 | t->block_gc++; | |
1437 | r = dns_transaction_request_dnssec_keys(t); | |
1438 | t->block_gc--; | |
1439 | ||
1440 | /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */ | |
1441 | if (!dns_transaction_gc(t)) | |
1442 | return; | |
1443 | ||
1444 | /* Requesting additional keys might have resulted in this transaction to fail, since the auxiliary | |
1445 | * request failed for some reason. If so, we are not in pending state anymore, and we should exit | |
1446 | * quickly. */ | |
1447 | if (t->state != DNS_TRANSACTION_PENDING) | |
1448 | return; | |
1449 | if (r < 0) | |
1450 | goto fail; | |
1451 | if (r > 0) { | |
1452 | /* There are DNSSEC transactions pending now. Update the state accordingly. */ | |
1453 | t->state = DNS_TRANSACTION_VALIDATING; | |
1454 | dns_transaction_close_connection(t, true); | |
1455 | dns_transaction_stop_timeout(t); | |
1456 | return; | |
1457 | } | |
1458 | ||
1459 | dns_transaction_process_dnssec(t); | |
1460 | return; | |
1461 | ||
1462 | fail: | |
1463 | dns_transaction_complete_errno(t, r); | |
1464 | } | |
1465 | ||
1466 | static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { | |
1467 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
1468 | DnsTransaction *t = ASSERT_PTR(userdata); | |
1469 | int r; | |
1470 | ||
1471 | assert(t->scope); | |
1472 | ||
1473 | r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p); | |
1474 | if (r < 0) { | |
1475 | if (ERRNO_IS_DISCONNECT(r)) { | |
1476 | usec_t usec; | |
1477 | ||
1478 | /* UDP connection failures get reported via ICMP and then are possibly delivered to us on the | |
1479 | * next recvmsg(). Treat this like a lost packet. */ | |
1480 | ||
1481 | log_debug_errno(r, "Connection failure for DNS UDP packet: %m"); | |
1482 | assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &usec) >= 0); | |
1483 | dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level); | |
1484 | ||
1485 | dns_transaction_close_connection(t, /* use_graveyard = */ false); | |
1486 | ||
1487 | if (dns_transaction_limited_retry(t)) /* Try a different server */ | |
1488 | return 0; | |
1489 | } | |
1490 | dns_transaction_complete_errno(t, r); | |
1491 | return 0; | |
1492 | } | |
1493 | if (r == 0) | |
1494 | /* Spurious wakeup without any data */ | |
1495 | return 0; | |
1496 | ||
1497 | r = dns_packet_validate_reply(p); | |
1498 | if (r < 0) { | |
1499 | log_debug_errno(r, "Received invalid DNS packet as response, ignoring: %m"); | |
1500 | return 0; | |
1501 | } | |
1502 | if (r == 0) { | |
1503 | log_debug("Received inappropriate DNS packet as response, ignoring."); | |
1504 | return 0; | |
1505 | } | |
1506 | ||
1507 | if (DNS_PACKET_ID(p) != t->id) { | |
1508 | log_debug("Received packet with incorrect transaction ID, ignoring."); | |
1509 | return 0; | |
1510 | } | |
1511 | ||
1512 | dns_transaction_process_reply(t, p, false); | |
1513 | return 0; | |
1514 | } | |
1515 | ||
1516 | static int dns_transaction_emit_udp(DnsTransaction *t) { | |
1517 | int r; | |
1518 | ||
1519 | assert(t); | |
1520 | ||
1521 | if (t->scope->protocol == DNS_PROTOCOL_DNS) { | |
1522 | ||
1523 | r = dns_transaction_pick_server(t); | |
1524 | if (r < 0) | |
1525 | return r; | |
1526 | ||
1527 | if (manager_server_is_stub(t->scope->manager, t->server)) | |
1528 | return -ELOOP; | |
1529 | ||
1530 | if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_UDP || DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level)) | |
1531 | return -EAGAIN; /* Sorry, can't do UDP, try TCP! */ | |
1532 | ||
1533 | if (!t->bypass && !dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(dns_transaction_key(t)->type)) | |
1534 | return -EOPNOTSUPP; | |
1535 | ||
1536 | if (r > 0 || t->dns_udp_fd < 0) { /* Server changed, or no connection yet. */ | |
1537 | int fd; | |
1538 | ||
1539 | dns_transaction_close_connection(t, true); | |
1540 | ||
1541 | /* Before we allocate a new UDP socket, let's process the graveyard a bit to free some fds */ | |
1542 | manager_socket_graveyard_process(t->scope->manager); | |
1543 | ||
1544 | fd = dns_scope_socket_udp(t->scope, t->server); | |
1545 | if (fd < 0) | |
1546 | return fd; | |
1547 | ||
1548 | r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t); | |
1549 | if (r < 0) { | |
1550 | safe_close(fd); | |
1551 | return r; | |
1552 | } | |
1553 | ||
1554 | (void) sd_event_source_set_description(t->dns_udp_event_source, "dns-transaction-udp"); | |
1555 | t->dns_udp_fd = fd; | |
1556 | } | |
1557 | ||
1558 | if (!t->bypass) { | |
1559 | r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level); | |
1560 | if (r < 0) | |
1561 | return r; | |
1562 | } | |
1563 | } else | |
1564 | dns_transaction_close_connection(t, true); | |
1565 | ||
1566 | r = dns_scope_emit_udp(t->scope, t->dns_udp_fd, t->server ? t->server->family : AF_UNSPEC, t->sent); | |
1567 | if (r < 0) | |
1568 | return r; | |
1569 | ||
1570 | dns_transaction_reset_answer(t); | |
1571 | ||
1572 | return 0; | |
1573 | } | |
1574 | ||
1575 | static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) { | |
1576 | DnsTransaction *t = ASSERT_PTR(userdata); | |
1577 | ||
1578 | assert(s); | |
1579 | ||
1580 | t->seen_timeout = true; | |
1581 | ||
1582 | if (t->initial_jitter_scheduled && !t->initial_jitter_elapsed) { | |
1583 | log_debug("Initial jitter phase for transaction %" PRIu16 " elapsed.", t->id); | |
1584 | t->initial_jitter_elapsed = true; | |
1585 | } else { | |
1586 | /* Timeout reached? Increase the timeout for the server used */ | |
1587 | switch (t->scope->protocol) { | |
1588 | ||
1589 | case DNS_PROTOCOL_DNS: | |
1590 | assert(t->server); | |
1591 | dns_server_packet_lost(t->server, t->stream ? IPPROTO_TCP : IPPROTO_UDP, t->current_feature_level); | |
1592 | break; | |
1593 | ||
1594 | case DNS_PROTOCOL_LLMNR: | |
1595 | case DNS_PROTOCOL_MDNS: | |
1596 | dns_scope_packet_lost(t->scope, usec - t->start_usec); | |
1597 | break; | |
1598 | ||
1599 | default: | |
1600 | assert_not_reached(); | |
1601 | } | |
1602 | ||
1603 | log_debug("Timeout reached on transaction %" PRIu16 ".", t->id); | |
1604 | } | |
1605 | ||
1606 | dns_transaction_retry(t, /* next_server= */ true); /* try a different server, but given this means | |
1607 | * packet loss, let's do so even if we already | |
1608 | * tried a bunch */ | |
1609 | return 0; | |
1610 | } | |
1611 | ||
1612 | static int dns_transaction_setup_timeout( | |
1613 | DnsTransaction *t, | |
1614 | usec_t timeout_usec /* relative */, | |
1615 | usec_t next_usec /* CLOCK_BOOTTIME */) { | |
1616 | ||
1617 | int r; | |
1618 | ||
1619 | assert(t); | |
1620 | ||
1621 | dns_transaction_stop_timeout(t); | |
1622 | ||
1623 | r = sd_event_add_time_relative( | |
1624 | t->scope->manager->event, | |
1625 | &t->timeout_event_source, | |
1626 | CLOCK_BOOTTIME, | |
1627 | timeout_usec, 0, | |
1628 | on_transaction_timeout, t); | |
1629 | if (r < 0) | |
1630 | return r; | |
1631 | ||
1632 | (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout"); | |
1633 | ||
1634 | t->next_attempt_after = next_usec; | |
1635 | t->state = DNS_TRANSACTION_PENDING; | |
1636 | return 0; | |
1637 | } | |
1638 | ||
1639 | static usec_t transaction_get_resend_timeout(DnsTransaction *t) { | |
1640 | assert(t); | |
1641 | assert(t->scope); | |
1642 | ||
1643 | switch (t->scope->protocol) { | |
1644 | ||
1645 | case DNS_PROTOCOL_DNS: | |
1646 | ||
1647 | if (t->stream) | |
1648 | return TRANSACTION_TCP_TIMEOUT_USEC; | |
1649 | ||
1650 | return TRANSACTION_UDP_TIMEOUT_USEC; | |
1651 | ||
1652 | case DNS_PROTOCOL_MDNS: | |
1653 | if (t->probing) | |
1654 | return MDNS_PROBING_INTERVAL_USEC; | |
1655 | ||
1656 | /* See RFC 6762 Section 5.1 suggests that timeout should be a few seconds. */ | |
1657 | assert(t->n_attempts > 0); | |
1658 | return (1 << (t->n_attempts - 1)) * USEC_PER_SEC; | |
1659 | ||
1660 | case DNS_PROTOCOL_LLMNR: | |
1661 | return t->scope->resend_timeout; | |
1662 | ||
1663 | default: | |
1664 | assert_not_reached(); | |
1665 | } | |
1666 | } | |
1667 | ||
1668 | static void dns_transaction_randomize_answer(DnsTransaction *t) { | |
1669 | int r; | |
1670 | ||
1671 | assert(t); | |
1672 | ||
1673 | /* Randomizes the order of the answer array. This is done for all cached responses, so that we return | |
1674 | * a different order each time. We do this only for DNS traffic, in order to do some minimal, crappy | |
1675 | * load balancing. We don't do this for LLMNR or mDNS, since the order (preferring link-local | |
1676 | * addresses, and such like) might have meaning there, and load balancing is pointless. */ | |
1677 | ||
1678 | if (t->scope->protocol != DNS_PROTOCOL_DNS) | |
1679 | return; | |
1680 | ||
1681 | /* No point in randomizing, if there's just one RR */ | |
1682 | if (dns_answer_size(t->answer) <= 1) | |
1683 | return; | |
1684 | ||
1685 | r = dns_answer_reserve_or_clone(&t->answer, 0); | |
1686 | if (r < 0) /* If this fails, just don't randomize, this is non-essential stuff after all */ | |
1687 | return (void) log_debug_errno(r, "Failed to clone answer record, not randomizing RR order of answer: %m"); | |
1688 | ||
1689 | dns_answer_randomize(t->answer); | |
1690 | } | |
1691 | ||
1692 | static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) { | |
1693 | int r; | |
1694 | ||
1695 | assert(t); | |
1696 | ||
1697 | /* Returns 0 if dns_transaction_complete() has been called. In that case the transaction and query | |
1698 | * candidate objects may have been invalidated and must not be accessed. Returns 1 if the transaction | |
1699 | * has been prepared. */ | |
1700 | ||
1701 | dns_transaction_stop_timeout(t); | |
1702 | ||
1703 | if (t->n_attempts == 1 && t->seen_timeout) | |
1704 | t->scope->manager->n_timeouts_total++; | |
1705 | ||
1706 | if (!dns_scope_network_good(t->scope)) { | |
1707 | dns_transaction_complete(t, DNS_TRANSACTION_NETWORK_DOWN); | |
1708 | return 0; | |
1709 | } | |
1710 | ||
1711 | if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) { | |
1712 | DnsTransactionState result; | |
1713 | ||
1714 | if (t->scope->protocol == DNS_PROTOCOL_LLMNR) | |
1715 | /* If we didn't find anything on LLMNR, it's not an error, but a failure to resolve | |
1716 | * the name. */ | |
1717 | result = DNS_TRANSACTION_NOT_FOUND; | |
1718 | else | |
1719 | result = DNS_TRANSACTION_ATTEMPTS_MAX_REACHED; | |
1720 | ||
1721 | dns_transaction_complete(t, result); | |
1722 | return 0; | |
1723 | } | |
1724 | ||
1725 | if (t->scope->protocol == DNS_PROTOCOL_LLMNR && t->tried_stream) { | |
1726 | /* If we already tried via a stream, then we don't | |
1727 | * retry on LLMNR. See RFC 4795, Section 2.7. */ | |
1728 | dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED); | |
1729 | return 0; | |
1730 | } | |
1731 | ||
1732 | t->n_attempts++; | |
1733 | t->start_usec = ts; | |
1734 | ||
1735 | dns_transaction_reset_answer(t); | |
1736 | dns_transaction_flush_dnssec_transactions(t); | |
1737 | ||
1738 | /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */ | |
1739 | if (t->scope->protocol == DNS_PROTOCOL_DNS && | |
1740 | !FLAGS_SET(t->query_flags, SD_RESOLVED_NO_TRUST_ANCHOR)) { | |
1741 | r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, dns_transaction_key(t), &t->answer); | |
1742 | if (r < 0) | |
1743 | return r; | |
1744 | if (r > 0) { | |
1745 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
1746 | t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR; | |
1747 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED|SD_RESOLVED_CONFIDENTIAL, true); | |
1748 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
1749 | return 0; | |
1750 | } | |
1751 | ||
1752 | if (dns_name_is_root(dns_resource_key_name(dns_transaction_key(t))) && | |
1753 | dns_transaction_key(t)->type == DNS_TYPE_DS) { | |
1754 | ||
1755 | /* Hmm, this is a request for the root DS? A DS RR doesn't exist in the root zone, | |
1756 | * and if our trust anchor didn't know it either, this means we cannot do any DNSSEC | |
1757 | * logic anymore. */ | |
1758 | ||
1759 | if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) { | |
1760 | /* We are in downgrade mode. In this case, synthesize an unsigned empty | |
1761 | * response, so that the any lookup depending on this one can continue | |
1762 | * assuming there was no DS, and hence the root zone was unsigned. */ | |
1763 | ||
1764 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
1765 | t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR; | |
1766 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); | |
1767 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL, true); | |
1768 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
1769 | } else | |
1770 | /* If we are not in downgrade mode, then fail the lookup, because we cannot | |
1771 | * reasonably answer it. There might be DS RRs, but we don't know them, and | |
1772 | * the DNS server won't tell them to us (and even if it would, we couldn't | |
1773 | * validate and trust them. */ | |
1774 | dns_transaction_complete(t, DNS_TRANSACTION_NO_TRUST_ANCHOR); | |
1775 | ||
1776 | return 0; | |
1777 | } | |
1778 | } | |
1779 | ||
1780 | /* Check the zone. */ | |
1781 | if (!FLAGS_SET(t->query_flags, SD_RESOLVED_NO_ZONE)) { | |
1782 | r = dns_zone_lookup(&t->scope->zone, dns_transaction_key(t), dns_scope_ifindex(t->scope), &t->answer, NULL, NULL); | |
1783 | if (r < 0) | |
1784 | return r; | |
1785 | if (r > 0) { | |
1786 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
1787 | t->answer_source = DNS_TRANSACTION_ZONE; | |
1788 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED|SD_RESOLVED_CONFIDENTIAL, true); | |
1789 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
1790 | return 0; | |
1791 | } | |
1792 | } | |
1793 | ||
1794 | /* Check the cache. */ | |
1795 | if (!FLAGS_SET(t->query_flags, SD_RESOLVED_NO_CACHE)) { | |
1796 | ||
1797 | /* Before trying the cache, let's make sure we figured out a server to use. Should this cause | |
1798 | * a change of server this might flush the cache. */ | |
1799 | (void) dns_scope_get_dns_server(t->scope); | |
1800 | ||
1801 | /* Let's then prune all outdated entries */ | |
1802 | dns_cache_prune(&t->scope->cache); | |
1803 | ||
1804 | /* For the initial attempt or when no stale data is requested, disable serve stale | |
1805 | * and answer the question from the cache (honors ttl property). | |
1806 | * On the second attempt, if StaleRetentionSec is greater than zero, | |
1807 | * try to answer the question using stale date (honors until property) */ | |
1808 | uint64_t query_flags = t->query_flags; | |
1809 | if (t->n_attempts == 1 || t->scope->manager->stale_retention_usec == 0) | |
1810 | query_flags |= SD_RESOLVED_NO_STALE; | |
1811 | ||
1812 | r = dns_cache_lookup( | |
1813 | &t->scope->cache, | |
1814 | dns_transaction_key(t), | |
1815 | query_flags, | |
1816 | &t->answer_rcode, | |
1817 | &t->answer, | |
1818 | &t->received, | |
1819 | &t->answer_query_flags, | |
1820 | &t->answer_dnssec_result); | |
1821 | if (r < 0) | |
1822 | return r; | |
1823 | if (r > 0) { | |
1824 | dns_transaction_randomize_answer(t); | |
1825 | ||
1826 | if (t->bypass && t->scope->protocol == DNS_PROTOCOL_DNS && !t->received) | |
1827 | /* When bypass mode is on, do not use cached data unless it came with a full | |
1828 | * packet. */ | |
1829 | dns_transaction_reset_answer(t); | |
1830 | else { | |
1831 | if (t->n_attempts > 1 && !FLAGS_SET(query_flags, SD_RESOLVED_NO_STALE)) { | |
1832 | ||
1833 | if (t->answer_rcode == DNS_RCODE_SUCCESS) { | |
1834 | if (t->seen_timeout) | |
1835 | t->scope->manager->n_timeouts_served_stale_total++; | |
1836 | else | |
1837 | t->scope->manager->n_failure_responses_served_stale_total++; | |
1838 | } | |
1839 | ||
1840 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
1841 | log_debug("Serve Stale response rcode=%s for %s", | |
1842 | FORMAT_DNS_RCODE(t->answer_rcode), | |
1843 | dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str)); | |
1844 | } | |
1845 | ||
1846 | t->answer_source = DNS_TRANSACTION_CACHE; | |
1847 | if (t->answer_rcode == DNS_RCODE_SUCCESS) | |
1848 | dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); | |
1849 | else { | |
1850 | if (t->received) | |
1851 | (void) dns_packet_ede_rcode(t->received, &t->answer_ede_rcode, &t->answer_ede_msg); | |
1852 | ||
1853 | dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE); | |
1854 | } | |
1855 | return 0; | |
1856 | } | |
1857 | } | |
1858 | } | |
1859 | ||
1860 | if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_NETWORK)) { | |
1861 | dns_transaction_complete(t, DNS_TRANSACTION_NO_SOURCE); | |
1862 | return 0; | |
1863 | } | |
1864 | ||
1865 | return 1; | |
1866 | } | |
1867 | ||
1868 | static int dns_packet_append_zone(DnsPacket *p, DnsTransaction *t, DnsResourceKey *k, unsigned *nscount) { | |
1869 | _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; | |
1870 | bool tentative; | |
1871 | int r; | |
1872 | ||
1873 | assert(p); | |
1874 | assert(t); | |
1875 | assert(k); | |
1876 | ||
1877 | if (k->type != DNS_TYPE_ANY) | |
1878 | return 0; | |
1879 | ||
1880 | r = dns_zone_lookup(&t->scope->zone, k, t->scope->link->ifindex, &answer, NULL, &tentative); | |
1881 | if (r < 0) | |
1882 | return r; | |
1883 | ||
1884 | return dns_packet_append_answer(p, answer, nscount); | |
1885 | } | |
1886 | ||
1887 | static int mdns_make_dummy_packet(DnsTransaction *t, DnsPacket **ret_packet, Set **ret_keys) { | |
1888 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
1889 | _cleanup_set_free_ Set *keys = NULL; | |
1890 | bool add_known_answers = false; | |
1891 | unsigned qdcount; | |
1892 | usec_t ts; | |
1893 | int r; | |
1894 | ||
1895 | assert(t); | |
1896 | assert(t->scope); | |
1897 | assert(t->scope->protocol == DNS_PROTOCOL_MDNS); | |
1898 | assert(ret_packet); | |
1899 | assert(ret_keys); | |
1900 | ||
1901 | r = dns_packet_new_query(&p, t->scope->protocol, 0, false); | |
1902 | if (r < 0) | |
1903 | return r; | |
1904 | ||
1905 | r = dns_packet_append_key(p, dns_transaction_key(t), 0, NULL); | |
1906 | if (r < 0) | |
1907 | return r; | |
1908 | ||
1909 | qdcount = 1; | |
1910 | ||
1911 | if (dns_key_is_shared(dns_transaction_key(t))) | |
1912 | add_known_answers = true; | |
1913 | ||
1914 | r = dns_packet_append_zone(p, t, dns_transaction_key(t), NULL); | |
1915 | if (r < 0) | |
1916 | return r; | |
1917 | ||
1918 | /* Save appended keys */ | |
1919 | r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(t)); | |
1920 | if (r < 0) | |
1921 | return r; | |
1922 | ||
1923 | assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &ts) >= 0); | |
1924 | ||
1925 | LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) { | |
1926 | ||
1927 | /* Skip ourselves */ | |
1928 | if (other == t) | |
1929 | continue; | |
1930 | ||
1931 | if (other->state != DNS_TRANSACTION_PENDING) | |
1932 | continue; | |
1933 | ||
1934 | if (other->next_attempt_after > ts) | |
1935 | continue; | |
1936 | ||
1937 | if (!set_contains(keys, dns_transaction_key(other))) { | |
1938 | size_t saved_packet_size; | |
1939 | ||
1940 | r = dns_packet_append_key(p, dns_transaction_key(other), 0, &saved_packet_size); | |
1941 | /* If we can't stuff more questions into the packet, just give up. | |
1942 | * One of the 'other' transactions will fire later and take care of the rest. */ | |
1943 | if (r == -EMSGSIZE) | |
1944 | break; | |
1945 | if (r < 0) | |
1946 | return r; | |
1947 | ||
1948 | r = dns_packet_append_zone(p, t, dns_transaction_key(other), NULL); | |
1949 | if (r == -EMSGSIZE) { | |
1950 | dns_packet_truncate(p, saved_packet_size); | |
1951 | break; | |
1952 | } | |
1953 | if (r < 0) | |
1954 | return r; | |
1955 | ||
1956 | r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(other)); | |
1957 | if (r < 0) | |
1958 | return r; | |
1959 | } | |
1960 | ||
1961 | r = dns_transaction_prepare(other, ts); | |
1962 | if (r < 0) | |
1963 | return r; | |
1964 | if (r == 0) | |
1965 | /* In this case, not only this transaction, but multiple transactions may be | |
1966 | * freed. Hence, we need to restart the loop. */ | |
1967 | return -EAGAIN; | |
1968 | ||
1969 | usec_t timeout = transaction_get_resend_timeout(other); | |
1970 | r = dns_transaction_setup_timeout(other, timeout, usec_add(ts, timeout)); | |
1971 | if (r < 0) | |
1972 | return r; | |
1973 | ||
1974 | if (dns_key_is_shared(dns_transaction_key(other))) | |
1975 | add_known_answers = true; | |
1976 | ||
1977 | qdcount++; | |
1978 | if (qdcount >= UINT16_MAX) | |
1979 | break; | |
1980 | } | |
1981 | ||
1982 | DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount); | |
1983 | ||
1984 | /* Append known answers section if we're asking for any shared record */ | |
1985 | if (add_known_answers) { | |
1986 | r = dns_cache_export_shared_to_packet(&t->scope->cache, p, ts, 0); | |
1987 | if (r < 0) | |
1988 | return r; | |
1989 | } | |
1990 | ||
1991 | *ret_packet = TAKE_PTR(p); | |
1992 | *ret_keys = TAKE_PTR(keys); | |
1993 | return add_known_answers; | |
1994 | } | |
1995 | ||
1996 | static int dns_transaction_make_packet_mdns(DnsTransaction *t) { | |
1997 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL, *dummy = NULL; | |
1998 | _cleanup_set_free_ Set *keys = NULL; | |
1999 | bool add_known_answers; | |
2000 | DnsResourceKey *k; | |
2001 | unsigned c; | |
2002 | int r; | |
2003 | ||
2004 | assert(t); | |
2005 | assert(t->scope->protocol == DNS_PROTOCOL_MDNS); | |
2006 | ||
2007 | /* Discard any previously prepared packet, so we can start over and coalesce again */ | |
2008 | t->sent = dns_packet_unref(t->sent); | |
2009 | ||
2010 | /* First, create a dummy packet to calculate the number of known answers to be appended in the first packet. */ | |
2011 | for (;;) { | |
2012 | r = mdns_make_dummy_packet(t, &dummy, &keys); | |
2013 | if (r == -EAGAIN) | |
2014 | continue; | |
2015 | if (r < 0) | |
2016 | return r; | |
2017 | ||
2018 | add_known_answers = r; | |
2019 | break; | |
2020 | } | |
2021 | ||
2022 | /* Then, create actual packet. */ | |
2023 | r = dns_packet_new_query(&p, t->scope->protocol, 0, false); | |
2024 | if (r < 0) | |
2025 | return r; | |
2026 | ||
2027 | /* Questions */ | |
2028 | c = 0; | |
2029 | SET_FOREACH(k, keys) { | |
2030 | r = dns_packet_append_key(p, k, 0, NULL); | |
2031 | if (r < 0) | |
2032 | return r; | |
2033 | c++; | |
2034 | } | |
2035 | DNS_PACKET_HEADER(p)->qdcount = htobe16(c); | |
2036 | ||
2037 | /* Known answers */ | |
2038 | if (add_known_answers) { | |
2039 | usec_t ts; | |
2040 | ||
2041 | assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &ts) >= 0); | |
2042 | ||
2043 | r = dns_cache_export_shared_to_packet(&t->scope->cache, p, ts, be16toh(DNS_PACKET_HEADER(dummy)->ancount)); | |
2044 | if (r < 0) | |
2045 | return r; | |
2046 | } | |
2047 | ||
2048 | /* Authorities */ | |
2049 | c = 0; | |
2050 | SET_FOREACH(k, keys) { | |
2051 | r = dns_packet_append_zone(p, t, k, &c); | |
2052 | if (r < 0) | |
2053 | return r; | |
2054 | } | |
2055 | DNS_PACKET_HEADER(p)->nscount = htobe16(c); | |
2056 | ||
2057 | t->sent = TAKE_PTR(p); | |
2058 | return 0; | |
2059 | } | |
2060 | ||
2061 | static int dns_transaction_make_packet(DnsTransaction *t) { | |
2062 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
2063 | int r; | |
2064 | ||
2065 | assert(t); | |
2066 | ||
2067 | if (t->scope->protocol == DNS_PROTOCOL_MDNS) | |
2068 | return dns_transaction_make_packet_mdns(t); | |
2069 | ||
2070 | if (t->sent) | |
2071 | return 0; | |
2072 | ||
2073 | if (t->bypass && t->bypass->protocol == t->scope->protocol) { | |
2074 | /* If bypass logic is enabled and the protocol if the original packet and our scope match, | |
2075 | * take the original packet, copy it, and patch in our new ID */ | |
2076 | r = dns_packet_dup(&p, t->bypass); | |
2077 | if (r < 0) | |
2078 | return r; | |
2079 | } else { | |
2080 | r = dns_packet_new_query( | |
2081 | &p, t->scope->protocol, | |
2082 | /* min_alloc_dsize = */ 0, | |
2083 | /* dnssec_checking_disabled = */ !FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) && | |
2084 | t->scope->dnssec_mode != DNSSEC_NO); | |
2085 | if (r < 0) | |
2086 | return r; | |
2087 | ||
2088 | r = dns_packet_append_key(p, dns_transaction_key(t), 0, NULL); | |
2089 | if (r < 0) | |
2090 | return r; | |
2091 | ||
2092 | DNS_PACKET_HEADER(p)->qdcount = htobe16(1); | |
2093 | } | |
2094 | ||
2095 | DNS_PACKET_HEADER(p)->id = t->id; | |
2096 | ||
2097 | t->sent = TAKE_PTR(p); | |
2098 | return 0; | |
2099 | } | |
2100 | ||
2101 | int dns_transaction_go(DnsTransaction *t) { | |
2102 | usec_t ts; | |
2103 | int r; | |
2104 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
2105 | ||
2106 | assert(t); | |
2107 | ||
2108 | /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has | |
2109 | * finished now. In the latter case, the transaction and query candidate objects must not be accessed. | |
2110 | */ | |
2111 | ||
2112 | assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &ts) >= 0); | |
2113 | ||
2114 | r = dns_transaction_prepare(t, ts); | |
2115 | if (r <= 0) | |
2116 | return r; | |
2117 | ||
2118 | log_debug("Firing %s transaction %" PRIu16 " for <%s> scope %s on %s/%s (validate=%s).", | |
2119 | t->bypass ? "bypass" : "regular", | |
2120 | t->id, | |
2121 | dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str), | |
2122 | dns_protocol_to_string(t->scope->protocol), | |
2123 | t->scope->link ? t->scope->link->ifname : "*", | |
2124 | af_to_name_short(t->scope->family), | |
2125 | yes_no(!FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE))); | |
2126 | ||
2127 | if (!t->initial_jitter_scheduled && | |
2128 | IN_SET(t->scope->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) { | |
2129 | usec_t jitter; | |
2130 | ||
2131 | /* RFC 4795 Section 2.7 suggests all LLMNR queries should be delayed by a random time from 0 to | |
2132 | * JITTER_INTERVAL. | |
2133 | * RFC 6762 Section 8.1 suggests initial probe queries should be delayed by a random time from | |
2134 | * 0 to 250ms. */ | |
2135 | ||
2136 | t->initial_jitter_scheduled = true; | |
2137 | t->n_attempts = 0; | |
2138 | ||
2139 | switch (t->scope->protocol) { | |
2140 | ||
2141 | case DNS_PROTOCOL_LLMNR: | |
2142 | jitter = random_u64_range(LLMNR_JITTER_INTERVAL_USEC); | |
2143 | break; | |
2144 | ||
2145 | case DNS_PROTOCOL_MDNS: | |
2146 | if (t->probing) | |
2147 | jitter = random_u64_range(MDNS_PROBING_INTERVAL_USEC); | |
2148 | else | |
2149 | jitter = 0; | |
2150 | break; | |
2151 | default: | |
2152 | assert_not_reached(); | |
2153 | } | |
2154 | ||
2155 | r = dns_transaction_setup_timeout(t, jitter, ts); | |
2156 | if (r < 0) | |
2157 | return r; | |
2158 | ||
2159 | log_debug("Delaying %s transaction %" PRIu16 " for " USEC_FMT "us.", | |
2160 | dns_protocol_to_string(t->scope->protocol), | |
2161 | t->id, | |
2162 | jitter); | |
2163 | return 1; | |
2164 | } | |
2165 | ||
2166 | /* Otherwise, we need to ask the network */ | |
2167 | r = dns_transaction_make_packet(t); | |
2168 | if (r < 0) | |
2169 | return r; | |
2170 | ||
2171 | if (t->scope->protocol == DNS_PROTOCOL_LLMNR && | |
2172 | (dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), "in-addr.arpa") > 0 || | |
2173 | dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), "ip6.arpa") > 0)) { | |
2174 | ||
2175 | /* RFC 4795, Section 2.4. says reverse lookups shall | |
2176 | * always be made via TCP on LLMNR */ | |
2177 | r = dns_transaction_emit_tcp(t); | |
2178 | } else { | |
2179 | /* Try via UDP, and if that fails due to large size or lack of | |
2180 | * support try via TCP */ | |
2181 | r = dns_transaction_emit_udp(t); | |
2182 | if (r == -EMSGSIZE) | |
2183 | log_debug("Sending query via TCP since it is too large."); | |
2184 | else if (r == -EAGAIN) | |
2185 | log_debug("Sending query via TCP since UDP isn't supported or DNS-over-TLS is selected."); | |
2186 | else if (r == -EPERM) | |
2187 | log_debug("Sending query via TCP since UDP is blocked."); | |
2188 | if (IN_SET(r, -EMSGSIZE, -EAGAIN, -EPERM)) | |
2189 | r = dns_transaction_emit_tcp(t); | |
2190 | } | |
2191 | if (r == -ELOOP) { | |
2192 | if (t->scope->protocol != DNS_PROTOCOL_DNS) | |
2193 | return r; | |
2194 | ||
2195 | /* One of our own stub listeners */ | |
2196 | log_debug_errno(r, "Detected that specified DNS server is our own extra listener, switching DNS servers."); | |
2197 | ||
2198 | dns_scope_next_dns_server(t->scope, t->server); | |
2199 | ||
2200 | if (dns_scope_get_dns_server(t->scope) == t->server) { | |
2201 | log_debug_errno(r, "Still pointing to extra listener after switching DNS servers, refusing operation."); | |
2202 | dns_transaction_complete(t, DNS_TRANSACTION_STUB_LOOP); | |
2203 | return 0; | |
2204 | } | |
2205 | ||
2206 | return dns_transaction_go(t); | |
2207 | } | |
2208 | if (r == -ESRCH) { | |
2209 | /* No servers to send this to? */ | |
2210 | dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS); | |
2211 | return 0; | |
2212 | } | |
2213 | if (r == -EOPNOTSUPP) { | |
2214 | /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */ | |
2215 | dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED); | |
2216 | return 0; | |
2217 | } | |
2218 | if (t->scope->protocol == DNS_PROTOCOL_LLMNR && ERRNO_IS_NEG_DISCONNECT(r)) { | |
2219 | /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot | |
2220 | * answer this request with this protocol. */ | |
2221 | dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND); | |
2222 | return 0; | |
2223 | } | |
2224 | if (r < 0) { | |
2225 | if (t->scope->protocol != DNS_PROTOCOL_DNS) | |
2226 | return r; | |
2227 | ||
2228 | /* Couldn't send? Try immediately again, with a new server */ | |
2229 | dns_scope_next_dns_server(t->scope, t->server); | |
2230 | ||
2231 | return dns_transaction_go(t); | |
2232 | } | |
2233 | ||
2234 | usec_t timeout = transaction_get_resend_timeout(t); | |
2235 | r = dns_transaction_setup_timeout(t, timeout, usec_add(ts, timeout)); | |
2236 | if (r < 0) | |
2237 | return r; | |
2238 | ||
2239 | return 1; | |
2240 | } | |
2241 | ||
2242 | static int dns_transaction_find_cyclic(DnsTransaction *t, DnsTransaction *aux) { | |
2243 | DnsTransaction *n; | |
2244 | int r; | |
2245 | ||
2246 | assert(t); | |
2247 | assert(aux); | |
2248 | ||
2249 | /* Try to find cyclic dependencies between transaction objects */ | |
2250 | ||
2251 | if (t == aux) | |
2252 | return 1; | |
2253 | ||
2254 | SET_FOREACH(n, aux->dnssec_transactions) { | |
2255 | r = dns_transaction_find_cyclic(t, n); | |
2256 | if (r != 0) | |
2257 | return r; | |
2258 | } | |
2259 | ||
2260 | return 0; | |
2261 | } | |
2262 | ||
2263 | static int dns_transaction_add_dnssec_transaction(DnsTransaction *t, DnsResourceKey *key, DnsTransaction **ret) { | |
2264 | _cleanup_(dns_transaction_gcp) DnsTransaction *aux = NULL; | |
2265 | int r; | |
2266 | ||
2267 | assert(t); | |
2268 | assert(ret); | |
2269 | assert(key); | |
2270 | ||
2271 | aux = dns_scope_find_transaction(t->scope, key, t->query_flags); | |
2272 | if (!aux) { | |
2273 | r = dns_transaction_new(&aux, t->scope, key, NULL, t->query_flags); | |
2274 | if (r < 0) | |
2275 | return r; | |
2276 | } else { | |
2277 | if (set_contains(t->dnssec_transactions, aux)) { | |
2278 | *ret = aux; | |
2279 | return 0; | |
2280 | } | |
2281 | ||
2282 | r = dns_transaction_find_cyclic(t, aux); | |
2283 | if (r < 0) | |
2284 | return r; | |
2285 | if (r > 0) { | |
2286 | char s[DNS_RESOURCE_KEY_STRING_MAX], saux[DNS_RESOURCE_KEY_STRING_MAX]; | |
2287 | ||
2288 | return log_debug_errno(SYNTHETIC_ERRNO(ELOOP), | |
2289 | "Potential cyclic dependency, refusing to add transaction %" PRIu16 " (%s) as dependency for %" PRIu16 " (%s).", | |
2290 | aux->id, | |
2291 | dns_resource_key_to_string(dns_transaction_key(t), s, sizeof s), | |
2292 | t->id, | |
2293 | dns_resource_key_to_string(dns_transaction_key(aux), saux, sizeof saux)); | |
2294 | } | |
2295 | } | |
2296 | ||
2297 | r = set_ensure_allocated(&aux->notify_transactions_done, NULL); | |
2298 | if (r < 0) | |
2299 | return r; | |
2300 | ||
2301 | r = set_ensure_put(&t->dnssec_transactions, NULL, aux); | |
2302 | if (r < 0) | |
2303 | return r; | |
2304 | ||
2305 | r = set_ensure_put(&aux->notify_transactions, NULL, t); | |
2306 | if (r < 0) { | |
2307 | (void) set_remove(t->dnssec_transactions, aux); | |
2308 | return r; | |
2309 | } | |
2310 | ||
2311 | *ret = TAKE_PTR(aux); | |
2312 | return 1; | |
2313 | } | |
2314 | ||
2315 | static int dns_transaction_request_dnssec_rr_full(DnsTransaction *t, DnsResourceKey *key, DnsTransaction **ret) { | |
2316 | _cleanup_(dns_answer_unrefp) DnsAnswer *a = NULL; | |
2317 | DnsTransaction *aux; | |
2318 | int r; | |
2319 | ||
2320 | assert(t); | |
2321 | assert(key); | |
2322 | ||
2323 | /* Try to get the data from the trust anchor */ | |
2324 | r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, key, &a); | |
2325 | if (r < 0) | |
2326 | return r; | |
2327 | if (r > 0) { | |
2328 | r = dns_answer_extend(&t->validated_keys, a); | |
2329 | if (r < 0) | |
2330 | return r; | |
2331 | ||
2332 | if (ret) | |
2333 | *ret = NULL; | |
2334 | return 0; | |
2335 | } | |
2336 | ||
2337 | /* This didn't work, ask for it via the network/cache then. */ | |
2338 | r = dns_transaction_add_dnssec_transaction(t, key, &aux); | |
2339 | if (r == -ELOOP) { /* This would result in a cyclic dependency */ | |
2340 | if (ret) | |
2341 | *ret = NULL; | |
2342 | return 0; | |
2343 | } | |
2344 | if (r < 0) | |
2345 | return r; | |
2346 | ||
2347 | if (aux->state == DNS_TRANSACTION_NULL) { | |
2348 | r = dns_transaction_go(aux); | |
2349 | if (r < 0) | |
2350 | return r; | |
2351 | } | |
2352 | if (ret) | |
2353 | *ret = aux; | |
2354 | ||
2355 | return 1; | |
2356 | } | |
2357 | ||
2358 | static int dns_transaction_request_dnssec_rr(DnsTransaction *t, DnsResourceKey *key) { | |
2359 | assert(t); | |
2360 | assert(key); | |
2361 | return dns_transaction_request_dnssec_rr_full(t, key, NULL); | |
2362 | } | |
2363 | ||
2364 | static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction *t, const char *name) { | |
2365 | int r; | |
2366 | ||
2367 | assert(t); | |
2368 | ||
2369 | /* Check whether the specified name is in the NTA | |
2370 | * database, either in the global one, or the link-local | |
2371 | * one. */ | |
2372 | ||
2373 | r = dns_trust_anchor_lookup_negative(&t->scope->manager->trust_anchor, name); | |
2374 | if (r != 0) | |
2375 | return r; | |
2376 | ||
2377 | if (!t->scope->link) | |
2378 | return 0; | |
2379 | ||
2380 | return link_negative_trust_anchor_lookup(t->scope->link, name); | |
2381 | } | |
2382 | ||
2383 | static int dns_transaction_has_negative_answer(DnsTransaction *t) { | |
2384 | int r; | |
2385 | ||
2386 | assert(t); | |
2387 | ||
2388 | /* Checks whether the answer is negative, and lacks NSEC/NSEC3 | |
2389 | * RRs to prove it */ | |
2390 | ||
2391 | r = dns_transaction_has_positive_answer(t, NULL); | |
2392 | if (r < 0) | |
2393 | return r; | |
2394 | if (r > 0) | |
2395 | return false; | |
2396 | ||
2397 | /* Is this key explicitly listed as a negative trust anchor? | |
2398 | * If so, it's nothing we need to care about */ | |
2399 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(dns_transaction_key(t))); | |
2400 | if (r < 0) | |
2401 | return r; | |
2402 | return !r; | |
2403 | } | |
2404 | ||
2405 | static int dns_transaction_is_primary_response(DnsTransaction *t, DnsResourceRecord *rr) { | |
2406 | int r; | |
2407 | ||
2408 | assert(t); | |
2409 | assert(rr); | |
2410 | ||
2411 | /* Check if the specified RR is the "primary" response, | |
2412 | * i.e. either matches the question precisely or is a | |
2413 | * CNAME/DNAME for it. */ | |
2414 | ||
2415 | r = dns_resource_key_match_rr(dns_transaction_key(t), rr, NULL); | |
2416 | if (r != 0) | |
2417 | return r; | |
2418 | ||
2419 | return dns_resource_key_match_cname_or_dname(dns_transaction_key(t), rr->key, NULL); | |
2420 | } | |
2421 | ||
2422 | static bool dns_transaction_dnssec_supported(DnsTransaction *t) { | |
2423 | assert(t); | |
2424 | ||
2425 | /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon | |
2426 | * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */ | |
2427 | ||
2428 | if (t->scope->protocol != DNS_PROTOCOL_DNS) | |
2429 | return false; | |
2430 | ||
2431 | /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well | |
2432 | * be supported, hence return true. */ | |
2433 | if (!t->server) | |
2434 | return true; | |
2435 | ||
2436 | /* Note that we do not check the feature level actually used for the transaction but instead the feature level | |
2437 | * the server is known to support currently, as the transaction feature level might be lower than what the | |
2438 | * server actually supports, since we might have downgraded this transaction's feature level because we got a | |
2439 | * SERVFAIL earlier and wanted to check whether downgrading fixes it. */ | |
2440 | ||
2441 | return dns_server_dnssec_supported(t->server); | |
2442 | } | |
2443 | ||
2444 | static bool dns_transaction_dnssec_supported_full(DnsTransaction *t) { | |
2445 | DnsTransaction *dt; | |
2446 | ||
2447 | assert(t); | |
2448 | ||
2449 | /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */ | |
2450 | ||
2451 | if (!dns_transaction_dnssec_supported(t)) | |
2452 | return false; | |
2453 | ||
2454 | SET_FOREACH(dt, t->dnssec_transactions) | |
2455 | if (!dns_transaction_dnssec_supported(dt)) | |
2456 | return false; | |
2457 | ||
2458 | return true; | |
2459 | } | |
2460 | ||
2461 | int dns_transaction_request_dnssec_keys(DnsTransaction *t) { | |
2462 | DnsResourceRecord *rr; | |
2463 | ||
2464 | /* Have we already requested a record that would be sufficient to validate an insecure delegation? */ | |
2465 | bool chased_insecure = false; | |
2466 | int r; | |
2467 | ||
2468 | assert(t); | |
2469 | ||
2470 | /* | |
2471 | * Retrieve all auxiliary RRs for the answer we got, so that | |
2472 | * we can verify signatures or prove that RRs are rightfully | |
2473 | * unsigned. Specifically: | |
2474 | * | |
2475 | * - For RRSIG we get the matching DNSKEY | |
2476 | * - For DNSKEY we get the matching DS | |
2477 | * - For unsigned SOA/NS we get the matching DS | |
2478 | * - For unsigned CNAME/DNAME/DS we get the parent DS RR | |
2479 | * - For other unsigned RRs we get the matching DS RR | |
2480 | * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR | |
2481 | * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's DS RR | |
2482 | * - For other queries with no matching response RRs, and no NSEC/NSEC3, the DS RR | |
2483 | */ | |
2484 | ||
2485 | if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) || t->scope->dnssec_mode == DNSSEC_NO) | |
2486 | return 0; | |
2487 | if (t->answer_source != DNS_TRANSACTION_NETWORK) | |
2488 | return 0; /* We only need to validate stuff from the network */ | |
2489 | if (!dns_transaction_dnssec_supported(t)) | |
2490 | return 0; /* If we can't do DNSSEC anyway there's no point in getting the auxiliary RRs */ | |
2491 | ||
2492 | DNS_ANSWER_FOREACH(rr, t->answer) { | |
2493 | ||
2494 | if (dns_type_is_pseudo(rr->key->type)) | |
2495 | continue; | |
2496 | ||
2497 | /* If this RR is in the negative trust anchor, we don't need to validate it. */ | |
2498 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key)); | |
2499 | if (r < 0) | |
2500 | return r; | |
2501 | if (r > 0) | |
2502 | continue; | |
2503 | ||
2504 | switch (rr->key->type) { | |
2505 | ||
2506 | case DNS_TYPE_RRSIG: { | |
2507 | /* For each RRSIG we request the matching DNSKEY */ | |
2508 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *dnskey = NULL; | |
2509 | DnsTransaction *aux; | |
2510 | ||
2511 | /* If this RRSIG is about a DNSKEY RR and the | |
2512 | * signer is the same as the owner, then we | |
2513 | * already have the DNSKEY, and we don't have | |
2514 | * to look for more. */ | |
2515 | if (rr->rrsig.type_covered == DNS_TYPE_DNSKEY) { | |
2516 | r = dns_name_equal(rr->rrsig.signer, dns_resource_key_name(rr->key)); | |
2517 | if (r < 0) | |
2518 | return r; | |
2519 | if (r > 0) | |
2520 | continue; | |
2521 | } | |
2522 | ||
2523 | /* If the signer is not a parent of our | |
2524 | * original query, then this is about an | |
2525 | * auxiliary RRset, but not anything we asked | |
2526 | * for. In this case we aren't interested, | |
2527 | * because we don't want to request additional | |
2528 | * RRs for stuff we didn't really ask for, and | |
2529 | * also to avoid request loops, where | |
2530 | * additional RRs from one transaction result | |
2531 | * in another transaction whose additional RRs | |
2532 | * point back to the original transaction, and | |
2533 | * we deadlock. */ | |
2534 | r = dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), rr->rrsig.signer); | |
2535 | if (r < 0) | |
2536 | return r; | |
2537 | if (r == 0) | |
2538 | continue; | |
2539 | ||
2540 | dnskey = dns_resource_key_new(rr->key->class, DNS_TYPE_DNSKEY, rr->rrsig.signer); | |
2541 | if (!dnskey) | |
2542 | return -ENOMEM; | |
2543 | ||
2544 | log_debug("Requesting DNSKEY to validate transaction %" PRIu16" (%s, RRSIG with key tag: %" PRIu16 ").", | |
2545 | t->id, dns_resource_key_name(rr->key), rr->rrsig.key_tag); | |
2546 | r = dns_transaction_request_dnssec_rr_full(t, dnskey, &aux); | |
2547 | if (r < 0) | |
2548 | return r; | |
2549 | ||
2550 | /* If we are requesting a DNSKEY, we can anticipate that we will want the matching DS | |
2551 | * in the near future. Let's request it in advance so we don't have to wait in the | |
2552 | * common case. */ | |
2553 | if (aux) { | |
2554 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = | |
2555 | dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(dnskey)); | |
2556 | if (!ds) | |
2557 | return -ENOMEM; | |
2558 | r = dns_transaction_request_dnssec_rr(t, ds); | |
2559 | if (r < 0) | |
2560 | return r; | |
2561 | } | |
2562 | break; | |
2563 | } | |
2564 | ||
2565 | case DNS_TYPE_DNSKEY: { | |
2566 | /* For each DNSKEY we request the matching DS */ | |
2567 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL; | |
2568 | ||
2569 | /* If the DNSKEY we are looking at is not for | |
2570 | * zone we are interested in, nor any of its | |
2571 | * parents, we aren't interested, and don't | |
2572 | * request it. After all, we don't want to end | |
2573 | * up in request loops, and want to keep | |
2574 | * additional traffic down. */ | |
2575 | ||
2576 | r = dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), dns_resource_key_name(rr->key)); | |
2577 | if (r < 0) | |
2578 | return r; | |
2579 | if (r == 0) | |
2580 | continue; | |
2581 | ||
2582 | ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key)); | |
2583 | if (!ds) | |
2584 | return -ENOMEM; | |
2585 | ||
2586 | log_debug("Requesting DS to validate transaction %" PRIu16" (%s, DNSKEY with key tag: %" PRIu16 ").", | |
2587 | t->id, dns_resource_key_name(rr->key), dnssec_keytag(rr, false)); | |
2588 | r = dns_transaction_request_dnssec_rr(t, ds); | |
2589 | if (r < 0) | |
2590 | return r; | |
2591 | ||
2592 | break; | |
2593 | } | |
2594 | ||
2595 | case DNS_TYPE_SOA: | |
2596 | case DNS_TYPE_NS: { | |
2597 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL; | |
2598 | ||
2599 | /* For an unsigned SOA or NS, try to acquire | |
2600 | * the matching DS RR, as we are at a zone cut | |
2601 | * then, and whether a DS exists tells us | |
2602 | * whether the zone is signed. Do so only if | |
2603 | * this RR matches our original question, | |
2604 | * however. */ | |
2605 | ||
2606 | r = dns_resource_key_match_rr(dns_transaction_key(t), rr, NULL); | |
2607 | if (r < 0) | |
2608 | return r; | |
2609 | if (r == 0) { | |
2610 | /* Hmm, so this SOA RR doesn't match our original question. In this case, maybe this is | |
2611 | * a negative reply, and we need the SOA RR's TTL in order to cache a negative entry? | |
2612 | * If so, we need to validate it, too. */ | |
2613 | ||
2614 | r = dns_answer_match_key(t->answer, dns_transaction_key(t), NULL); | |
2615 | if (r < 0) | |
2616 | return r; | |
2617 | if (r > 0) /* positive reply, we won't need the SOA and hence don't need to validate | |
2618 | * it. */ | |
2619 | continue; | |
2620 | ||
2621 | /* Only bother with this if the SOA/NS RR we are looking at is actually a parent of | |
2622 | * what we are looking for, otherwise there's no value in it for us. */ | |
2623 | r = dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), dns_resource_key_name(rr->key)); | |
2624 | if (r < 0) | |
2625 | return r; | |
2626 | if (r == 0) | |
2627 | continue; | |
2628 | ||
2629 | /* If we were looking for the DS RR, don't request it again. */ | |
2630 | if (dns_transaction_key(t)->type == DNS_TYPE_DS) | |
2631 | continue; | |
2632 | } | |
2633 | ||
2634 | r = dnssec_has_rrsig(t->answer, rr->key); | |
2635 | if (r < 0) | |
2636 | return r; | |
2637 | if (r > 0) | |
2638 | continue; | |
2639 | ||
2640 | chased_insecure = true; | |
2641 | ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key)); | |
2642 | if (!ds) | |
2643 | return -ENOMEM; | |
2644 | ||
2645 | log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned SOA/NS RRset).", | |
2646 | t->id, dns_resource_key_name(rr->key)); | |
2647 | r = dns_transaction_request_dnssec_rr(t, ds); | |
2648 | if (r < 0) | |
2649 | return r; | |
2650 | ||
2651 | break; | |
2652 | } | |
2653 | ||
2654 | case DNS_TYPE_DS: | |
2655 | case DNS_TYPE_CNAME: | |
2656 | case DNS_TYPE_DNAME: { | |
2657 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL; | |
2658 | const char *name; | |
2659 | ||
2660 | /* CNAMEs and DNAMEs cannot be located at a | |
2661 | * zone apex, hence ask for the parent DS for | |
2662 | * unsigned CNAME/DNAME RRs, maybe that's the | |
2663 | * apex. But do all that only if this is | |
2664 | * actually a response to our original | |
2665 | * question. | |
2666 | * | |
2667 | * Similar for DS RRs, which are signed when | |
2668 | * the parent SOA is signed. */ | |
2669 | ||
2670 | r = dns_transaction_is_primary_response(t, rr); | |
2671 | if (r < 0) | |
2672 | return r; | |
2673 | if (r == 0) | |
2674 | continue; | |
2675 | ||
2676 | r = dnssec_has_rrsig(t->answer, rr->key); | |
2677 | if (r < 0) | |
2678 | return r; | |
2679 | if (r > 0) | |
2680 | continue; | |
2681 | ||
2682 | r = dns_answer_has_dname_for_cname(t->answer, rr); | |
2683 | if (r < 0) | |
2684 | return r; | |
2685 | if (r > 0) | |
2686 | continue; | |
2687 | ||
2688 | name = dns_resource_key_name(rr->key); | |
2689 | r = dns_name_parent(&name); | |
2690 | if (r < 0) | |
2691 | return r; | |
2692 | if (r == 0) | |
2693 | continue; | |
2694 | ||
2695 | ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, name); | |
2696 | if (!ds) | |
2697 | return -ENOMEM; | |
2698 | ||
2699 | log_debug("Requesting parent DS to validate transaction %" PRIu16 " (%s, unsigned CNAME/DNAME/DS RRset).", | |
2700 | t->id, dns_resource_key_name(rr->key)); | |
2701 | r = dns_transaction_request_dnssec_rr(t, ds); | |
2702 | if (r < 0) | |
2703 | return r; | |
2704 | ||
2705 | if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE && dns_name_is_root(name)) { | |
2706 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL; | |
2707 | /* We made it all the way to the root zone. If we are in allow-downgrade | |
2708 | * mode, we need to make at least one request that we can be certain should | |
2709 | * have been signed, to test for servers that are not dnssec aware. */ | |
2710 | soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, name); | |
2711 | if (!soa) | |
2712 | return -ENOMEM; | |
2713 | ||
2714 | log_debug("Requesting root zone SOA to probe dnssec support."); | |
2715 | r = dns_transaction_request_dnssec_rr(t, soa); | |
2716 | if (r < 0) | |
2717 | return r; | |
2718 | } | |
2719 | ||
2720 | break; | |
2721 | } | |
2722 | ||
2723 | default: { | |
2724 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL; | |
2725 | ||
2726 | /* For other unsigned RRsets (including | |
2727 | * NSEC/NSEC3!), look for proof the zone is | |
2728 | * unsigned, by requesting the DS RR of the | |
2729 | * zone. However, do so only if they are | |
2730 | * directly relevant to our original | |
2731 | * question. */ | |
2732 | ||
2733 | r = dns_transaction_is_primary_response(t, rr); | |
2734 | if (r < 0) | |
2735 | return r; | |
2736 | if (r == 0) | |
2737 | continue; | |
2738 | ||
2739 | r = dnssec_has_rrsig(t->answer, rr->key); | |
2740 | if (r < 0) | |
2741 | return r; | |
2742 | if (r > 0) | |
2743 | continue; | |
2744 | ||
2745 | ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key)); | |
2746 | if (!ds) | |
2747 | return -ENOMEM; | |
2748 | ||
2749 | log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned non-SOA/NS RRset <%s>).", | |
2750 | t->id, dns_resource_key_name(rr->key), dns_resource_record_to_string(rr)); | |
2751 | r = dns_transaction_request_dnssec_rr(t, ds); | |
2752 | if (r < 0) | |
2753 | return r; | |
2754 | break; | |
2755 | }} | |
2756 | } | |
2757 | ||
2758 | /* Above, we requested everything necessary to validate what | |
2759 | * we got. Now, let's request what we need to validate what we | |
2760 | * didn't get... */ | |
2761 | ||
2762 | r = dns_transaction_has_negative_answer(t); | |
2763 | if (r < 0) | |
2764 | return r; | |
2765 | if (r > 0) { | |
2766 | const char *name = dns_resource_key_name(dns_transaction_key(t)); | |
2767 | bool was_signed = dns_answer_contains_nsec_or_nsec3(t->answer); | |
2768 | ||
2769 | /* If the response is empty, seek the DS for this name, just in case we're at a zone cut | |
2770 | * already, unless we just requested the DS, in which case we have to ask the parent to make | |
2771 | * progress. | |
2772 | * | |
2773 | * If this was an SOA or NS request, we could also skip to the parent, but in real world | |
2774 | * setups there are too many broken DNS servers (Hello, incapdns.net!) where non-terminal | |
2775 | * zones return NXDOMAIN even though they have further children. */ | |
2776 | ||
2777 | if (chased_insecure || was_signed) | |
2778 | /* In this case we already requested what we need above. */ | |
2779 | name = NULL; | |
2780 | else if (dns_transaction_key(t)->type == DNS_TYPE_DS) | |
2781 | /* If the DS response is empty, we'll walk up the dns labels requesting DS until we | |
2782 | * find a referral to the SOA or hit it anyway and get a positive DS response. */ | |
2783 | if (dns_name_parent(&name) <= 0) | |
2784 | name = NULL; | |
2785 | ||
2786 | if (name) { | |
2787 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL; | |
2788 | ||
2789 | log_debug("Requesting DS (%s %s) to validate transaction %" PRIu16 " (%s empty response).", | |
2790 | glyph(GLYPH_ARROW_RIGHT), name, t->id, | |
2791 | dns_resource_key_name(dns_transaction_key(t))); | |
2792 | ||
2793 | ds = dns_resource_key_new(dns_transaction_key(t)->class, DNS_TYPE_DS, name); | |
2794 | if (!ds) | |
2795 | return -ENOMEM; | |
2796 | ||
2797 | r = dns_transaction_request_dnssec_rr(t, ds); | |
2798 | if (r < 0) | |
2799 | return r; | |
2800 | } | |
2801 | } | |
2802 | ||
2803 | return dns_transaction_dnssec_is_live(t); | |
2804 | } | |
2805 | ||
2806 | DnsResourceKey* dns_transaction_key(DnsTransaction *t) { | |
2807 | assert(t); | |
2808 | ||
2809 | /* Return the lookup key of this transaction. Either takes the lookup key from the bypass packet if | |
2810 | * we are a bypass transaction. Or take the configured key for regular transactions. */ | |
2811 | ||
2812 | if (t->key) | |
2813 | return t->key; | |
2814 | ||
2815 | assert(t->bypass); | |
2816 | ||
2817 | return dns_question_first_key(t->bypass->question); | |
2818 | } | |
2819 | ||
2820 | void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source) { | |
2821 | assert(t); | |
2822 | assert(source); | |
2823 | ||
2824 | /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING, | |
2825 | we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If | |
2826 | the state is VALIDATING however, we should check if we are complete now. */ | |
2827 | ||
2828 | if (t->state == DNS_TRANSACTION_VALIDATING) | |
2829 | dns_transaction_process_dnssec(t); | |
2830 | } | |
2831 | ||
2832 | static int dns_transaction_validate_dnskey_by_ds(DnsTransaction *t) { | |
2833 | DnsAnswerItem *item; | |
2834 | int r; | |
2835 | ||
2836 | assert(t); | |
2837 | ||
2838 | /* Add all DNSKEY RRs from the answer that are validated by DS | |
2839 | * RRs from the list of validated keys to the list of | |
2840 | * validated keys. */ | |
2841 | ||
2842 | DNS_ANSWER_FOREACH_ITEM(item, t->answer) { | |
2843 | ||
2844 | r = dnssec_verify_dnskey_by_ds_search(item->rr, t->validated_keys); | |
2845 | if (r < 0) | |
2846 | return r; | |
2847 | if (r == 0) | |
2848 | continue; | |
2849 | ||
2850 | /* If so, the DNSKEY is validated too. */ | |
2851 | r = dns_answer_add_extend(&t->validated_keys, item->rr, item->ifindex, item->flags|DNS_ANSWER_AUTHENTICATED, item->rrsig); | |
2852 | if (r < 0) | |
2853 | return r; | |
2854 | } | |
2855 | ||
2856 | return 0; | |
2857 | } | |
2858 | ||
2859 | static int dns_transaction_requires_rrsig(DnsTransaction *t, DnsResourceRecord *rr) { | |
2860 | int r; | |
2861 | ||
2862 | assert(t); | |
2863 | assert(rr); | |
2864 | ||
2865 | /* Checks if the RR we are looking for must be signed with an | |
2866 | * RRSIG. This is used for positive responses. */ | |
2867 | ||
2868 | if (t->scope->dnssec_mode == DNSSEC_NO) | |
2869 | return false; | |
2870 | ||
2871 | if (dns_type_is_pseudo(rr->key->type)) | |
2872 | return -EINVAL; | |
2873 | ||
2874 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key)); | |
2875 | if (r < 0) | |
2876 | return r; | |
2877 | if (r > 0) | |
2878 | return false; | |
2879 | ||
2880 | switch (rr->key->type) { | |
2881 | ||
2882 | case DNS_TYPE_RRSIG: | |
2883 | /* RRSIGs are the signatures themselves, they need no signing. */ | |
2884 | return false; | |
2885 | ||
2886 | case DNS_TYPE_SOA: | |
2887 | case DNS_TYPE_NS: { | |
2888 | DnsTransaction *dt; | |
2889 | ||
2890 | /* For SOA or NS RRs we look for a matching DS transaction */ | |
2891 | SET_FOREACH(dt, t->dnssec_transactions) { | |
2892 | ||
2893 | if (dns_transaction_key(dt)->class != rr->key->class) | |
2894 | continue; | |
2895 | if (dns_transaction_key(dt)->type != DNS_TYPE_DS) | |
2896 | continue; | |
2897 | ||
2898 | r = dns_name_endswith(dns_resource_key_name(rr->key), dns_resource_key_name(dns_transaction_key(dt))); | |
2899 | if (r < 0) | |
2900 | return r; | |
2901 | if (r == 0) | |
2902 | continue; | |
2903 | ||
2904 | /* We found a DS transactions for the SOA/NS | |
2905 | * RRs we are looking at. If it discovered signed DS | |
2906 | * RRs, then we need to be signed, too. */ | |
2907 | ||
2908 | if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) | |
2909 | return false; | |
2910 | ||
2911 | return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL); | |
2912 | } | |
2913 | ||
2914 | /* We found nothing that proves this is safe to leave | |
2915 | * this unauthenticated, hence ask inist on | |
2916 | * authentication. */ | |
2917 | return true; | |
2918 | } | |
2919 | ||
2920 | case DNS_TYPE_DS: | |
2921 | case DNS_TYPE_CNAME: | |
2922 | case DNS_TYPE_DNAME: { | |
2923 | const char *parent = NULL; | |
2924 | DnsTransaction *dt; | |
2925 | ||
2926 | /* | |
2927 | * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent DS. | |
2928 | * | |
2929 | * DS RRs are signed if the parent is signed, hence also look at the parent DS | |
2930 | */ | |
2931 | ||
2932 | SET_FOREACH(dt, t->dnssec_transactions) { | |
2933 | ||
2934 | if (dns_transaction_key(dt)->class != rr->key->class) | |
2935 | continue; | |
2936 | if (dns_transaction_key(dt)->type != DNS_TYPE_DS) | |
2937 | continue; | |
2938 | ||
2939 | if (!parent) { | |
2940 | parent = dns_resource_key_name(rr->key); | |
2941 | r = dns_name_parent(&parent); | |
2942 | if (r < 0) | |
2943 | return r; | |
2944 | if (r == 0) { | |
2945 | if (rr->key->type == DNS_TYPE_DS) | |
2946 | return true; | |
2947 | ||
2948 | /* A CNAME/DNAME without a parent? That's sooo weird. */ | |
2949 | return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG), | |
2950 | "Transaction %" PRIu16 " claims CNAME/DNAME at root. Refusing.", t->id); | |
2951 | } | |
2952 | } | |
2953 | ||
2954 | r = dns_name_endswith(parent, dns_resource_key_name(dns_transaction_key(dt))); | |
2955 | if (r < 0) | |
2956 | return r; | |
2957 | if (r == 0) | |
2958 | continue; | |
2959 | ||
2960 | if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) | |
2961 | return false; | |
2962 | ||
2963 | /* We expect this to be signed when the DS record exists, and don't expect it to be | |
2964 | * signed when the DS record is proven not to exist. */ | |
2965 | return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL); | |
2966 | } | |
2967 | ||
2968 | return true; | |
2969 | } | |
2970 | ||
2971 | default: { | |
2972 | DnsTransaction *dt; | |
2973 | ||
2974 | /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our DS lookup was authenticated */ | |
2975 | ||
2976 | SET_FOREACH(dt, t->dnssec_transactions) { | |
2977 | if (dns_transaction_key(dt)->class != rr->key->class) | |
2978 | continue; | |
2979 | if (dns_transaction_key(dt)->type != DNS_TYPE_DS) | |
2980 | continue; | |
2981 | ||
2982 | r = dns_name_endswith(dns_resource_key_name(rr->key), dns_resource_key_name(dns_transaction_key(dt))); | |
2983 | if (r < 0) | |
2984 | return r; | |
2985 | if (r == 0) | |
2986 | continue; | |
2987 | ||
2988 | if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) | |
2989 | return false; | |
2990 | ||
2991 | /* We expect this to be signed when the DS record exists, and don't expect it to be | |
2992 | * signed when the DS record is proven not to exist. */ | |
2993 | return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL); | |
2994 | } | |
2995 | ||
2996 | return true; | |
2997 | }} | |
2998 | } | |
2999 | ||
3000 | static int dns_transaction_in_private_tld(DnsTransaction *t, const DnsResourceKey *key) { | |
3001 | DnsTransaction *dt; | |
3002 | const char *tld; | |
3003 | int r; | |
3004 | ||
3005 | /* If DNSSEC downgrade mode is on, checks whether the | |
3006 | * specified RR is one level below a TLD we have proven not to | |
3007 | * exist. In such a case we assume that this is a private | |
3008 | * domain, and permit it. | |
3009 | * | |
3010 | * This detects cases like the Fritz!Box router networks. Each | |
3011 | * Fritz!Box router serves a private "fritz.box" zone, in the | |
3012 | * non-existing TLD "box". Requests for the "fritz.box" domain | |
3013 | * are served by the router itself, while requests for the | |
3014 | * "box" domain will result in NXDOMAIN. | |
3015 | * | |
3016 | * Note that this logic is unable to detect cases where a | |
3017 | * router serves a private DNS zone directly under | |
3018 | * non-existing TLD. In such a case we cannot detect whether | |
3019 | * the TLD is supposed to exist or not, as all requests we | |
3020 | * make for it will be answered by the router's zone, and not | |
3021 | * by the root zone. */ | |
3022 | ||
3023 | assert(t); | |
3024 | ||
3025 | if (t->scope->dnssec_mode != DNSSEC_ALLOW_DOWNGRADE) | |
3026 | return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */ | |
3027 | ||
3028 | tld = dns_resource_key_name(key); | |
3029 | r = dns_name_parent(&tld); | |
3030 | if (r < 0) | |
3031 | return r; | |
3032 | if (r == 0) | |
3033 | return false; /* Already the root domain */ | |
3034 | ||
3035 | if (!dns_name_is_single_label(tld)) | |
3036 | return false; | |
3037 | ||
3038 | SET_FOREACH(dt, t->dnssec_transactions) { | |
3039 | ||
3040 | if (dns_transaction_key(dt)->class != key->class) | |
3041 | continue; | |
3042 | ||
3043 | r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), tld); | |
3044 | if (r < 0) | |
3045 | return r; | |
3046 | if (r == 0) | |
3047 | continue; | |
3048 | ||
3049 | /* We found an auxiliary lookup we did for the TLD. If | |
3050 | * that returned with NXDOMAIN, we know the TLD didn't | |
3051 | * exist, and hence this might be a private zone. */ | |
3052 | ||
3053 | return dt->answer_rcode == DNS_RCODE_NXDOMAIN; | |
3054 | } | |
3055 | ||
3056 | return false; | |
3057 | } | |
3058 | ||
3059 | static int dns_transaction_requires_nsec(DnsTransaction *t) { | |
3060 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
3061 | DnsTransaction *dt; | |
3062 | const char *name; | |
3063 | int r; | |
3064 | ||
3065 | assert(t); | |
3066 | ||
3067 | /* Checks if we need to insist on NSEC/NSEC3 RRs for proving | |
3068 | * this negative reply */ | |
3069 | ||
3070 | if (t->scope->dnssec_mode == DNSSEC_NO) | |
3071 | return false; | |
3072 | ||
3073 | if (dns_type_is_pseudo(dns_transaction_key(t)->type)) | |
3074 | return -EINVAL; | |
3075 | ||
3076 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(dns_transaction_key(t))); | |
3077 | if (r < 0) | |
3078 | return r; | |
3079 | if (r > 0) | |
3080 | return false; | |
3081 | ||
3082 | r = dns_transaction_in_private_tld(t, dns_transaction_key(t)); | |
3083 | if (r < 0) | |
3084 | return r; | |
3085 | if (r > 0) { | |
3086 | /* The lookup is from a TLD that is proven not to | |
3087 | * exist, and we are in downgrade mode, hence ignore | |
3088 | * that fact that we didn't get any NSEC RRs. */ | |
3089 | ||
3090 | log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.", | |
3091 | dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str)); | |
3092 | return false; | |
3093 | } | |
3094 | ||
3095 | name = dns_resource_key_name(dns_transaction_key(t)); | |
3096 | ||
3097 | /* For all other RRs we check the DS on the same level to see | |
3098 | * if it's signed. */ | |
3099 | ||
3100 | SET_FOREACH(dt, t->dnssec_transactions) { | |
3101 | if (dns_transaction_key(dt)->class != dns_transaction_key(t)->class) | |
3102 | continue; | |
3103 | if (dns_transaction_key(dt)->type != DNS_TYPE_DS) | |
3104 | continue; | |
3105 | ||
3106 | r = dns_name_endswith(name, dns_resource_key_name(dns_transaction_key(dt))); | |
3107 | if (r < 0) | |
3108 | return r; | |
3109 | if (r == 0) | |
3110 | continue; | |
3111 | ||
3112 | if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) | |
3113 | return false; | |
3114 | ||
3115 | /* We expect this to be signed when the DS record exists, and don't expect it to be signed | |
3116 | * when the DS record is proven not to exist. */ | |
3117 | return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL); | |
3118 | } | |
3119 | ||
3120 | /* If in doubt, require NSEC/NSEC3 */ | |
3121 | return true; | |
3122 | } | |
3123 | ||
3124 | static int dns_transaction_dnskey_authenticated(DnsTransaction *t, DnsResourceRecord *rr) { | |
3125 | DnsResourceRecord *rrsig; | |
3126 | bool found = false; | |
3127 | int r; | |
3128 | ||
3129 | /* Checks whether any of the DNSKEYs used for the RRSIGs for | |
3130 | * the specified RRset is authenticated (i.e. has a matching | |
3131 | * DS RR). */ | |
3132 | ||
3133 | r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key)); | |
3134 | if (r < 0) | |
3135 | return r; | |
3136 | if (r > 0) | |
3137 | return false; | |
3138 | ||
3139 | DNS_ANSWER_FOREACH(rrsig, t->answer) { | |
3140 | DnsTransaction *dt; | |
3141 | ||
3142 | r = dnssec_key_match_rrsig(rr->key, rrsig); | |
3143 | if (r < 0) | |
3144 | return r; | |
3145 | if (r == 0) | |
3146 | continue; | |
3147 | ||
3148 | SET_FOREACH(dt, t->dnssec_transactions) { | |
3149 | ||
3150 | if (dns_transaction_key(dt)->class != rr->key->class) | |
3151 | continue; | |
3152 | ||
3153 | if (dns_transaction_key(dt)->type == DNS_TYPE_DNSKEY) { | |
3154 | ||
3155 | r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), rrsig->rrsig.signer); | |
3156 | if (r < 0) | |
3157 | return r; | |
3158 | if (r == 0) | |
3159 | continue; | |
3160 | ||
3161 | /* OK, we found an auxiliary DNSKEY lookup. If that lookup is authenticated, | |
3162 | * report this. */ | |
3163 | ||
3164 | if (FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) | |
3165 | return true; | |
3166 | ||
3167 | found = true; | |
3168 | ||
3169 | } else if (dns_transaction_key(dt)->type == DNS_TYPE_DS) { | |
3170 | ||
3171 | r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), rrsig->rrsig.signer); | |
3172 | if (r < 0) | |
3173 | return r; | |
3174 | if (r == 0) | |
3175 | continue; | |
3176 | ||
3177 | /* OK, we found an auxiliary DS lookup. If that lookup is authenticated and | |
3178 | * non-zero, we won! */ | |
3179 | ||
3180 | if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) | |
3181 | return false; | |
3182 | ||
3183 | return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL); | |
3184 | } | |
3185 | } | |
3186 | } | |
3187 | ||
3188 | return found ? false : -ENXIO; | |
3189 | } | |
3190 | ||
3191 | static int dns_transaction_known_signed(DnsTransaction *t, DnsResourceRecord *rr) { | |
3192 | assert(t); | |
3193 | assert(rr); | |
3194 | ||
3195 | /* We know that the root domain is signed, hence if it appears | |
3196 | * not to be signed, there's a problem with the DNS server */ | |
3197 | ||
3198 | return rr->key->class == DNS_CLASS_IN && | |
3199 | dns_name_is_root(dns_resource_key_name(rr->key)); | |
3200 | } | |
3201 | ||
3202 | static int dns_transaction_check_revoked_trust_anchors(DnsTransaction *t) { | |
3203 | DnsResourceRecord *rr; | |
3204 | int r; | |
3205 | ||
3206 | assert(t); | |
3207 | ||
3208 | /* Maybe warn the user that we encountered a revoked DNSKEY | |
3209 | * for a key from our trust anchor. Note that we don't care | |
3210 | * whether the DNSKEY can be authenticated or not. It's | |
3211 | * sufficient if it is self-signed. */ | |
3212 | ||
3213 | DNS_ANSWER_FOREACH(rr, t->answer) { | |
3214 | r = dns_trust_anchor_check_revoked(&t->scope->manager->trust_anchor, rr, t->answer); | |
3215 | if (r < 0) | |
3216 | return r; | |
3217 | } | |
3218 | ||
3219 | return 0; | |
3220 | } | |
3221 | ||
3222 | static int dns_transaction_invalidate_revoked_keys(DnsTransaction *t) { | |
3223 | bool changed; | |
3224 | int r; | |
3225 | ||
3226 | assert(t); | |
3227 | ||
3228 | /* Removes all DNSKEY/DS objects from t->validated_keys that | |
3229 | * our trust anchors database considers revoked. */ | |
3230 | ||
3231 | do { | |
3232 | DnsResourceRecord *rr; | |
3233 | ||
3234 | changed = false; | |
3235 | ||
3236 | DNS_ANSWER_FOREACH(rr, t->validated_keys) { | |
3237 | r = dns_trust_anchor_is_revoked(&t->scope->manager->trust_anchor, rr); | |
3238 | if (r < 0) | |
3239 | return r; | |
3240 | if (r > 0) { | |
3241 | r = dns_answer_remove_by_rr(&t->validated_keys, rr); | |
3242 | if (r < 0) | |
3243 | return r; | |
3244 | ||
3245 | assert(r > 0); | |
3246 | changed = true; | |
3247 | break; | |
3248 | } | |
3249 | } | |
3250 | } while (changed); | |
3251 | ||
3252 | return 0; | |
3253 | } | |
3254 | ||
3255 | static int dns_transaction_copy_validated(DnsTransaction *t) { | |
3256 | DnsTransaction *dt; | |
3257 | int r; | |
3258 | ||
3259 | assert(t); | |
3260 | ||
3261 | /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */ | |
3262 | ||
3263 | SET_FOREACH(dt, t->dnssec_transactions) { | |
3264 | ||
3265 | if (DNS_TRANSACTION_IS_LIVE(dt->state)) | |
3266 | continue; | |
3267 | ||
3268 | if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) | |
3269 | continue; | |
3270 | ||
3271 | r = dns_answer_extend(&t->validated_keys, dt->answer); | |
3272 | if (r < 0) | |
3273 | return r; | |
3274 | } | |
3275 | ||
3276 | return 0; | |
3277 | } | |
3278 | ||
3279 | typedef enum { | |
3280 | DNSSEC_PHASE_DNSKEY, /* Phase #1, only validate DNSKEYs */ | |
3281 | DNSSEC_PHASE_NSEC, /* Phase #2, only validate NSEC+NSEC3 */ | |
3282 | DNSSEC_PHASE_ALL, /* Phase #3, validate everything else */ | |
3283 | } Phase; | |
3284 | ||
3285 | static int dnssec_validate_records( | |
3286 | DnsTransaction *t, | |
3287 | Phase phase, | |
3288 | bool *have_nsec, | |
3289 | unsigned *nvalidations, | |
3290 | DnsAnswer **validated) { | |
3291 | ||
3292 | DnsResourceRecord *rr; | |
3293 | int r; | |
3294 | ||
3295 | assert(nvalidations); | |
3296 | ||
3297 | /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */ | |
3298 | ||
3299 | DNS_ANSWER_FOREACH(rr, t->answer) { | |
3300 | _unused_ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr_ref = dns_resource_record_ref(rr); | |
3301 | DnsResourceRecord *rrsig = NULL; | |
3302 | DnssecResult result; | |
3303 | ||
3304 | switch (rr->key->type) { | |
3305 | case DNS_TYPE_RRSIG: | |
3306 | continue; | |
3307 | ||
3308 | case DNS_TYPE_DNSKEY: | |
3309 | /* We validate DNSKEYs only in the DNSKEY and ALL phases */ | |
3310 | if (phase == DNSSEC_PHASE_NSEC) | |
3311 | continue; | |
3312 | break; | |
3313 | ||
3314 | case DNS_TYPE_NSEC: | |
3315 | case DNS_TYPE_NSEC3: | |
3316 | *have_nsec = true; | |
3317 | ||
3318 | /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */ | |
3319 | if (phase == DNSSEC_PHASE_DNSKEY) | |
3320 | continue; | |
3321 | break; | |
3322 | ||
3323 | default: | |
3324 | /* We validate all other RRs only in the ALL phases */ | |
3325 | if (phase != DNSSEC_PHASE_ALL) | |
3326 | continue; | |
3327 | } | |
3328 | ||
3329 | r = dnssec_verify_rrset_search( | |
3330 | t->answer, | |
3331 | rr->key, | |
3332 | t->validated_keys, | |
3333 | USEC_INFINITY, | |
3334 | &result, | |
3335 | &rrsig); | |
3336 | if (r < 0) | |
3337 | return r; | |
3338 | *nvalidations += r; | |
3339 | ||
3340 | log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr)), dnssec_result_to_string(result)); | |
3341 | ||
3342 | if (result == DNSSEC_VALIDATED) { | |
3343 | assert(rrsig); | |
3344 | ||
3345 | if (rr->key->type == DNS_TYPE_DNSKEY) { | |
3346 | /* If we just validated a DNSKEY RRset, then let's add these keys to | |
3347 | * the set of validated keys for this transaction. */ | |
3348 | ||
3349 | r = dns_answer_copy_by_key(&t->validated_keys, t->answer, rr->key, DNS_ANSWER_AUTHENTICATED, rrsig); | |
3350 | if (r < 0) | |
3351 | return r; | |
3352 | ||
3353 | /* Some of the DNSKEYs we just added might already have been revoked, | |
3354 | * remove them again in that case. */ | |
3355 | r = dns_transaction_invalidate_revoked_keys(t); | |
3356 | if (r < 0) | |
3357 | return r; | |
3358 | } | |
3359 | ||
3360 | /* Add the validated RRset to the new list of validated RRsets, and remove it from | |
3361 | * the unvalidated RRsets. We mark the RRset as authenticated and cacheable. */ | |
3362 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE, rrsig); | |
3363 | if (r < 0) | |
3364 | return r; | |
3365 | ||
3366 | manager_dnssec_verdict(t->scope->manager, DNSSEC_SECURE, rr->key); | |
3367 | ||
3368 | /* Exit the loop, we dropped something from the answer, start from the beginning */ | |
3369 | return 1; | |
3370 | } | |
3371 | ||
3372 | /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as | |
3373 | * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet, | |
3374 | * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */ | |
3375 | if (phase != DNSSEC_PHASE_ALL) | |
3376 | continue; | |
3377 | ||
3378 | if (result == DNSSEC_VALIDATED_WILDCARD) { | |
3379 | bool authenticated = false; | |
3380 | const char *source; | |
3381 | ||
3382 | assert(rrsig); | |
3383 | ||
3384 | /* This RRset validated, but as a wildcard. This means we need | |
3385 | * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists. */ | |
3386 | ||
3387 | /* First step, determine the source of synthesis */ | |
3388 | r = dns_resource_record_source(rrsig, &source); | |
3389 | if (r < 0) | |
3390 | return r; | |
3391 | ||
3392 | r = dnssec_test_positive_wildcard(*validated, | |
3393 | dns_resource_key_name(rr->key), | |
3394 | source, | |
3395 | rrsig->rrsig.signer, | |
3396 | &authenticated); | |
3397 | ||
3398 | /* Unless the NSEC proof showed that the key really doesn't exist something is off. */ | |
3399 | if (r == 0) | |
3400 | result = DNSSEC_INVALID; | |
3401 | else { | |
3402 | r = dns_answer_move_by_key( | |
3403 | validated, | |
3404 | &t->answer, | |
3405 | rr->key, | |
3406 | authenticated ? (DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE) : 0, | |
3407 | rrsig); | |
3408 | if (r < 0) | |
3409 | return r; | |
3410 | ||
3411 | manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, rr->key); | |
3412 | ||
3413 | /* Exit the loop, we dropped something from the answer, start from the beginning */ | |
3414 | return 1; | |
3415 | } | |
3416 | } | |
3417 | ||
3418 | if (result == DNSSEC_NO_SIGNATURE) { | |
3419 | r = dns_transaction_requires_rrsig(t, rr); | |
3420 | if (r < 0) | |
3421 | return r; | |
3422 | if (r == 0) { | |
3423 | /* Data does not require signing. In that case, just copy it over, | |
3424 | * but remember that this is by no means authenticated. */ | |
3425 | r = dns_answer_move_by_key( | |
3426 | validated, | |
3427 | &t->answer, | |
3428 | rr->key, | |
3429 | 0, | |
3430 | NULL); | |
3431 | if (r < 0) | |
3432 | return r; | |
3433 | ||
3434 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); | |
3435 | return 1; | |
3436 | } | |
3437 | ||
3438 | r = dns_transaction_known_signed(t, rr); | |
3439 | if (r < 0) | |
3440 | return r; | |
3441 | if (r > 0) { | |
3442 | /* This is an RR we know has to be signed. If it isn't this means | |
3443 | * the server is not attaching RRSIGs, hence complain. */ | |
3444 | ||
3445 | dns_server_packet_rrsig_missing(t->server, t->current_feature_level); | |
3446 | ||
3447 | if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) { | |
3448 | ||
3449 | /* Downgrading is OK? If so, just consider the information unsigned */ | |
3450 | ||
3451 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL); | |
3452 | if (r < 0) | |
3453 | return r; | |
3454 | ||
3455 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); | |
3456 | return 1; | |
3457 | } | |
3458 | ||
3459 | /* Otherwise, fail */ | |
3460 | t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER; | |
3461 | return 0; | |
3462 | } | |
3463 | ||
3464 | r = dns_transaction_in_private_tld(t, rr->key); | |
3465 | if (r < 0) | |
3466 | return r; | |
3467 | if (r > 0) { | |
3468 | char s[DNS_RESOURCE_KEY_STRING_MAX]; | |
3469 | ||
3470 | /* The data is from a TLD that is proven not to exist, and we are in downgrade | |
3471 | * mode, hence ignore the fact that this was not signed. */ | |
3472 | ||
3473 | log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.", | |
3474 | dns_resource_key_to_string(rr->key, s, sizeof s)); | |
3475 | ||
3476 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL); | |
3477 | if (r < 0) | |
3478 | return r; | |
3479 | ||
3480 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); | |
3481 | return 1; | |
3482 | } | |
3483 | } | |
3484 | ||
3485 | /* https://datatracker.ietf.org/doc/html/rfc6840#section-5.2 */ | |
3486 | if (result == DNSSEC_UNSUPPORTED_ALGORITHM) { | |
3487 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL); | |
3488 | if (r < 0) | |
3489 | return r; | |
3490 | ||
3491 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); | |
3492 | return 1; | |
3493 | } | |
3494 | ||
3495 | if (IN_SET(result, | |
3496 | DNSSEC_MISSING_KEY, | |
3497 | DNSSEC_SIGNATURE_EXPIRED)) { | |
3498 | ||
3499 | r = dns_transaction_dnskey_authenticated(t, rr); | |
3500 | if (r < 0 && r != -ENXIO) | |
3501 | return r; | |
3502 | if (r == 0) { | |
3503 | /* The DNSKEY transaction was not authenticated, this means there's | |
3504 | * no DS for this, which means it's OK if no keys are found for this signature. */ | |
3505 | ||
3506 | r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL); | |
3507 | if (r < 0) | |
3508 | return r; | |
3509 | ||
3510 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); | |
3511 | return 1; | |
3512 | } | |
3513 | } | |
3514 | ||
3515 | r = dns_transaction_is_primary_response(t, rr); | |
3516 | if (r < 0) | |
3517 | return r; | |
3518 | if (r > 0) { | |
3519 | /* Look for a matching DNAME for this CNAME */ | |
3520 | r = dns_answer_has_dname_for_cname(t->answer, rr); | |
3521 | if (r < 0) | |
3522 | return r; | |
3523 | if (r == 0) { | |
3524 | /* Also look among the stuff we already validated */ | |
3525 | r = dns_answer_has_dname_for_cname(*validated, rr); | |
3526 | if (r < 0) | |
3527 | return r; | |
3528 | } | |
3529 | ||
3530 | if (r == 0) { | |
3531 | if (IN_SET(result, | |
3532 | DNSSEC_INVALID, | |
3533 | DNSSEC_SIGNATURE_EXPIRED, | |
3534 | DNSSEC_NO_SIGNATURE)) | |
3535 | manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, rr->key); | |
3536 | else /* DNSSEC_MISSING_KEY, DNSSEC_UNSUPPORTED_ALGORITHM, | |
3537 | or DNSSEC_TOO_MANY_VALIDATIONS */ | |
3538 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, rr->key); | |
3539 | ||
3540 | /* This is a primary response to our question, and it failed validation. | |
3541 | * That's fatal. */ | |
3542 | t->answer_dnssec_result = result; | |
3543 | return 0; | |
3544 | } | |
3545 | ||
3546 | /* This is a primary response, but we do have a DNAME RR | |
3547 | * in the RR that can replay this CNAME, hence rely on | |
3548 | * that, and we can remove the CNAME in favour of it. */ | |
3549 | } | |
3550 | ||
3551 | /* This is just some auxiliary data. Just remove the RRset and continue. */ | |
3552 | r = dns_answer_remove_by_key(&t->answer, rr->key); | |
3553 | if (r < 0) | |
3554 | return r; | |
3555 | ||
3556 | /* We dropped something from the answer, start from the beginning. */ | |
3557 | return 1; | |
3558 | } | |
3559 | ||
3560 | return 2; /* Finito. */ | |
3561 | } | |
3562 | ||
3563 | int dns_transaction_validate_dnssec(DnsTransaction *t) { | |
3564 | _cleanup_(dns_answer_unrefp) DnsAnswer *validated = NULL; | |
3565 | Phase phase; | |
3566 | DnsAnswerFlags flags; | |
3567 | int r; | |
3568 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
3569 | ||
3570 | assert(t); | |
3571 | ||
3572 | /* We have now collected all DS and DNSKEY RRs in t->validated_keys, let's see which RRs we can now | |
3573 | * authenticate with that. */ | |
3574 | ||
3575 | if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) || t->scope->dnssec_mode == DNSSEC_NO) | |
3576 | return 0; | |
3577 | ||
3578 | /* Already validated */ | |
3579 | if (t->answer_dnssec_result != _DNSSEC_RESULT_INVALID) | |
3580 | return 0; | |
3581 | ||
3582 | /* Our own stuff needs no validation */ | |
3583 | if (IN_SET(t->answer_source, DNS_TRANSACTION_ZONE, DNS_TRANSACTION_TRUST_ANCHOR)) { | |
3584 | t->answer_dnssec_result = DNSSEC_VALIDATED; | |
3585 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, true); | |
3586 | return 0; | |
3587 | } | |
3588 | ||
3589 | /* Cached stuff is not affected by validation. */ | |
3590 | if (t->answer_source != DNS_TRANSACTION_NETWORK) | |
3591 | return 0; | |
3592 | ||
3593 | if (!dns_transaction_dnssec_supported_full(t)) { | |
3594 | /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */ | |
3595 | t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER; | |
3596 | log_debug("Not validating response for %" PRIu16 ", used server feature level does not support DNSSEC.", t->id); | |
3597 | return 0; | |
3598 | } | |
3599 | ||
3600 | log_debug("Validating response from transaction %" PRIu16 " (%s).", | |
3601 | t->id, | |
3602 | dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str)); | |
3603 | ||
3604 | /* First, see if this response contains any revoked trust | |
3605 | * anchors we care about */ | |
3606 | r = dns_transaction_check_revoked_trust_anchors(t); | |
3607 | if (r < 0) | |
3608 | return r; | |
3609 | ||
3610 | /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */ | |
3611 | r = dns_transaction_copy_validated(t); | |
3612 | if (r < 0) | |
3613 | return r; | |
3614 | ||
3615 | /* Second, see if there are DNSKEYs we already know a | |
3616 | * validated DS for. */ | |
3617 | r = dns_transaction_validate_dnskey_by_ds(t); | |
3618 | if (r < 0) | |
3619 | return r; | |
3620 | ||
3621 | /* Fourth, remove all DNSKEY and DS RRs again that our trust | |
3622 | * anchor says are revoked. After all we might have marked | |
3623 | * some keys revoked above, but they might still be lingering | |
3624 | * in our validated_keys list. */ | |
3625 | r = dns_transaction_invalidate_revoked_keys(t); | |
3626 | if (r < 0) | |
3627 | return r; | |
3628 | ||
3629 | phase = DNSSEC_PHASE_DNSKEY; | |
3630 | for (unsigned nvalidations = 0;;) { | |
3631 | bool have_nsec = false; | |
3632 | ||
3633 | r = dnssec_validate_records(t, phase, &have_nsec, &nvalidations, &validated); | |
3634 | if (r <= 0) { | |
3635 | DNS_ANSWER_REPLACE(t->answer, TAKE_PTR(validated)); | |
3636 | return r; | |
3637 | } | |
3638 | ||
3639 | if (nvalidations > DNSSEC_VALIDATION_MAX) { | |
3640 | /* This reply requires an onerous number of signature validations to verify. Let's | |
3641 | * not waste our time trying, as this shouldn't happen for well-behaved domains | |
3642 | * anyway. */ | |
3643 | t->answer_dnssec_result = DNSSEC_TOO_MANY_VALIDATIONS; | |
3644 | DNS_ANSWER_REPLACE(t->answer, TAKE_PTR(validated)); | |
3645 | return 0; | |
3646 | } | |
3647 | ||
3648 | /* Try again as long as we managed to achieve something */ | |
3649 | if (r == 1) | |
3650 | continue; | |
3651 | ||
3652 | if (phase == DNSSEC_PHASE_DNSKEY && have_nsec) { | |
3653 | /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */ | |
3654 | phase = DNSSEC_PHASE_NSEC; | |
3655 | continue; | |
3656 | } | |
3657 | ||
3658 | if (phase != DNSSEC_PHASE_ALL) { | |
3659 | /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now. | |
3660 | * Note that in this third phase we start to remove RRs we couldn't validate. */ | |
3661 | phase = DNSSEC_PHASE_ALL; | |
3662 | continue; | |
3663 | } | |
3664 | ||
3665 | /* We're done */ | |
3666 | break; | |
3667 | } | |
3668 | ||
3669 | DNS_ANSWER_REPLACE(t->answer, TAKE_PTR(validated)); | |
3670 | ||
3671 | /* At this point the answer only contains validated | |
3672 | * RRsets. Now, let's see if it actually answers the question | |
3673 | * we asked. If so, great! If it doesn't, then see if | |
3674 | * NSEC/NSEC3 can prove this. */ | |
3675 | r = dns_transaction_has_positive_answer(t, &flags); | |
3676 | if (r > 0) { | |
3677 | /* Yes, it answers the question! */ | |
3678 | ||
3679 | if (flags & DNS_ANSWER_AUTHENTICATED) { | |
3680 | /* The answer is fully authenticated, yay. */ | |
3681 | t->answer_dnssec_result = DNSSEC_VALIDATED; | |
3682 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
3683 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, true); | |
3684 | } else { | |
3685 | /* The answer is not fully authenticated. */ | |
3686 | t->answer_dnssec_result = DNSSEC_UNSIGNED; | |
3687 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); | |
3688 | } | |
3689 | ||
3690 | } else if (r == 0) { | |
3691 | DnssecNsecResult nr; | |
3692 | bool authenticated = false; | |
3693 | ||
3694 | /* Bummer! Let's check NSEC/NSEC3 */ | |
3695 | r = dnssec_nsec_test(t->answer, dns_transaction_key(t), &nr, &authenticated, &t->answer_nsec_ttl); | |
3696 | if (r < 0) | |
3697 | return r; | |
3698 | ||
3699 | switch (nr) { | |
3700 | ||
3701 | case DNSSEC_NSEC_NXDOMAIN: | |
3702 | /* NSEC proves the domain doesn't exist. Very good. */ | |
3703 | log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str); | |
3704 | t->answer_dnssec_result = DNSSEC_VALIDATED; | |
3705 | t->answer_rcode = DNS_RCODE_NXDOMAIN; | |
3706 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, authenticated); | |
3707 | ||
3708 | manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, dns_transaction_key(t)); | |
3709 | break; | |
3710 | ||
3711 | case DNSSEC_NSEC_NODATA: | |
3712 | /* NSEC proves that there's no data here, very good. */ | |
3713 | log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str); | |
3714 | t->answer_dnssec_result = DNSSEC_VALIDATED; | |
3715 | t->answer_rcode = DNS_RCODE_SUCCESS; | |
3716 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, authenticated); | |
3717 | ||
3718 | manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, dns_transaction_key(t)); | |
3719 | break; | |
3720 | ||
3721 | case DNSSEC_NSEC_OPTOUT: | |
3722 | /* NSEC3 says the data might not be signed */ | |
3723 | log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str); | |
3724 | t->answer_dnssec_result = DNSSEC_UNSIGNED; | |
3725 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); | |
3726 | ||
3727 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, dns_transaction_key(t)); | |
3728 | break; | |
3729 | ||
3730 | case DNSSEC_NSEC_NO_RR: | |
3731 | /* No NSEC data? Bummer! */ | |
3732 | ||
3733 | r = dns_transaction_requires_nsec(t); | |
3734 | if (r < 0) | |
3735 | return r; | |
3736 | if (r > 0) { | |
3737 | t->answer_dnssec_result = DNSSEC_NO_SIGNATURE; | |
3738 | manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, dns_transaction_key(t)); | |
3739 | } else { | |
3740 | t->answer_dnssec_result = DNSSEC_UNSIGNED; | |
3741 | SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); | |
3742 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, dns_transaction_key(t)); | |
3743 | } | |
3744 | ||
3745 | break; | |
3746 | ||
3747 | case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM: | |
3748 | /* We don't know the NSEC3 algorithm used? */ | |
3749 | t->answer_dnssec_result = DNSSEC_UNSUPPORTED_ALGORITHM; | |
3750 | manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, dns_transaction_key(t)); | |
3751 | break; | |
3752 | ||
3753 | case DNSSEC_NSEC_FOUND: | |
3754 | case DNSSEC_NSEC_CNAME: | |
3755 | /* NSEC says it needs to be there, but we couldn't find it? Bummer! */ | |
3756 | t->answer_dnssec_result = DNSSEC_NSEC_MISMATCH; | |
3757 | manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, dns_transaction_key(t)); | |
3758 | break; | |
3759 | ||
3760 | default: | |
3761 | assert_not_reached(); | |
3762 | } | |
3763 | } | |
3764 | ||
3765 | return 1; | |
3766 | } | |
3767 | ||
3768 | static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] = { | |
3769 | [DNS_TRANSACTION_NULL] = "null", | |
3770 | [DNS_TRANSACTION_PENDING] = "pending", | |
3771 | [DNS_TRANSACTION_VALIDATING] = "validating", | |
3772 | [DNS_TRANSACTION_RCODE_FAILURE] = "rcode-failure", | |
3773 | [DNS_TRANSACTION_SUCCESS] = "success", | |
3774 | [DNS_TRANSACTION_NO_SERVERS] = "no-servers", | |
3775 | [DNS_TRANSACTION_TIMEOUT] = "timeout", | |
3776 | [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED] = "attempts-max-reached", | |
3777 | [DNS_TRANSACTION_INVALID_REPLY] = "invalid-reply", | |
3778 | [DNS_TRANSACTION_ERRNO] = "errno", | |
3779 | [DNS_TRANSACTION_ABORTED] = "aborted", | |
3780 | [DNS_TRANSACTION_DNSSEC_FAILED] = "dnssec-failed", | |
3781 | [DNS_TRANSACTION_NO_TRUST_ANCHOR] = "no-trust-anchor", | |
3782 | [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED] = "rr-type-unsupported", | |
3783 | [DNS_TRANSACTION_NETWORK_DOWN] = "network-down", | |
3784 | [DNS_TRANSACTION_NOT_FOUND] = "not-found", | |
3785 | [DNS_TRANSACTION_NO_SOURCE] = "no-source", | |
3786 | [DNS_TRANSACTION_STUB_LOOP] = "stub-loop", | |
3787 | }; | |
3788 | DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state, DnsTransactionState); | |
3789 | ||
3790 | static const char* const dns_transaction_source_table[_DNS_TRANSACTION_SOURCE_MAX] = { | |
3791 | [DNS_TRANSACTION_NETWORK] = "network", | |
3792 | [DNS_TRANSACTION_CACHE] = "cache", | |
3793 | [DNS_TRANSACTION_ZONE] = "zone", | |
3794 | [DNS_TRANSACTION_TRUST_ANCHOR] = "trust-anchor", | |
3795 | }; | |
3796 | DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source, DnsTransactionSource); |