2 This file is part of systemd.
4 Copyright 2014 Lennart Poettering
6 systemd is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version.
11 systemd is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public License
17 along with systemd; If not, see <http://www.gnu.org/licenses/>.
20 #include <sd-messages.h>
23 #include "alloc-util.h"
24 #include "dns-domain.h"
25 #include "errno-list.h"
27 #include "random-util.h"
28 #include "resolved-dns-cache.h"
29 #include "resolved-dns-transaction.h"
30 #include "resolved-llmnr.h"
31 #include "string-table.h"
33 #define TRANSACTIONS_MAX 4096
35 static void dns_transaction_reset_answer(DnsTransaction
*t
) {
38 t
->received
= dns_packet_unref(t
->received
);
39 t
->answer
= dns_answer_unref(t
->answer
);
41 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
42 t
->answer_source
= _DNS_TRANSACTION_SOURCE_INVALID
;
43 t
->answer_authenticated
= false;
44 t
->answer_nsec_ttl
= (uint32_t) -1;
48 static void dns_transaction_flush_dnssec_transactions(DnsTransaction
*t
) {
53 while ((z
= set_steal_first(t
->dnssec_transactions
))) {
54 set_remove(z
->notify_transactions
, t
);
55 set_remove(z
->notify_transactions_done
, t
);
56 dns_transaction_gc(z
);
60 static void dns_transaction_close_connection(DnsTransaction
*t
) {
64 /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */
65 t
->stream
->complete
= NULL
;
66 t
->stream
->on_packet
= NULL
;
67 t
->stream
->transaction
= NULL
;
68 t
->stream
= dns_stream_unref(t
->stream
);
71 t
->dns_udp_event_source
= sd_event_source_unref(t
->dns_udp_event_source
);
72 t
->dns_udp_fd
= safe_close(t
->dns_udp_fd
);
75 static void dns_transaction_stop_timeout(DnsTransaction
*t
) {
78 t
->timeout_event_source
= sd_event_source_unref(t
->timeout_event_source
);
81 DnsTransaction
* dns_transaction_free(DnsTransaction
*t
) {
89 log_debug("Freeing transaction %" PRIu16
".", t
->id
);
91 dns_transaction_close_connection(t
);
92 dns_transaction_stop_timeout(t
);
94 dns_packet_unref(t
->sent
);
95 dns_transaction_reset_answer(t
);
97 dns_server_unref(t
->server
);
100 hashmap_remove_value(t
->scope
->transactions_by_key
, t
->key
, t
);
101 LIST_REMOVE(transactions_by_scope
, t
->scope
->transactions
, t
);
104 hashmap_remove(t
->scope
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
));
107 while ((c
= set_steal_first(t
->notify_query_candidates
)))
108 set_remove(c
->transactions
, t
);
109 set_free(t
->notify_query_candidates
);
111 while ((c
= set_steal_first(t
->notify_query_candidates_done
)))
112 set_remove(c
->transactions
, t
);
113 set_free(t
->notify_query_candidates_done
);
115 while ((i
= set_steal_first(t
->notify_zone_items
)))
116 i
->probe_transaction
= NULL
;
117 set_free(t
->notify_zone_items
);
119 while ((i
= set_steal_first(t
->notify_zone_items_done
)))
120 i
->probe_transaction
= NULL
;
121 set_free(t
->notify_zone_items_done
);
123 while ((z
= set_steal_first(t
->notify_transactions
)))
124 set_remove(z
->dnssec_transactions
, t
);
125 set_free(t
->notify_transactions
);
127 while ((z
= set_steal_first(t
->notify_transactions_done
)))
128 set_remove(z
->dnssec_transactions
, t
);
129 set_free(t
->notify_transactions_done
);
131 dns_transaction_flush_dnssec_transactions(t
);
132 set_free(t
->dnssec_transactions
);
134 dns_answer_unref(t
->validated_keys
);
135 dns_resource_key_unref(t
->key
);
140 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction
*, dns_transaction_free
);
142 bool dns_transaction_gc(DnsTransaction
*t
) {
148 if (set_isempty(t
->notify_query_candidates
) &&
149 set_isempty(t
->notify_query_candidates_done
) &&
150 set_isempty(t
->notify_zone_items
) &&
151 set_isempty(t
->notify_zone_items_done
) &&
152 set_isempty(t
->notify_transactions
) &&
153 set_isempty(t
->notify_transactions_done
)) {
154 dns_transaction_free(t
);
161 static uint16_t pick_new_id(Manager
*m
) {
164 /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the number of
165 * transactions, and it's much lower than the space of IDs. */
167 assert_cc(TRANSACTIONS_MAX
< 0xFFFF);
170 random_bytes(&new_id
, sizeof(new_id
));
171 while (new_id
== 0 ||
172 hashmap_get(m
->dns_transactions
, UINT_TO_PTR(new_id
)));
177 int dns_transaction_new(DnsTransaction
**ret
, DnsScope
*s
, DnsResourceKey
*key
) {
178 _cleanup_(dns_transaction_freep
) DnsTransaction
*t
= NULL
;
185 /* Don't allow looking up invalid or pseudo RRs */
186 if (!dns_type_is_valid_query(key
->type
))
188 if (dns_type_is_obsolete(key
->type
))
191 /* We only support the IN class */
192 if (key
->class != DNS_CLASS_IN
&& key
->class != DNS_CLASS_ANY
)
195 if (hashmap_size(s
->manager
->dns_transactions
) >= TRANSACTIONS_MAX
)
198 r
= hashmap_ensure_allocated(&s
->manager
->dns_transactions
, NULL
);
202 r
= hashmap_ensure_allocated(&s
->transactions_by_key
, &dns_resource_key_hash_ops
);
206 t
= new0(DnsTransaction
, 1);
211 t
->answer_source
= _DNS_TRANSACTION_SOURCE_INVALID
;
212 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
213 t
->answer_nsec_ttl
= (uint32_t) -1;
214 t
->key
= dns_resource_key_ref(key
);
215 t
->current_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
216 t
->clamp_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
218 t
->id
= pick_new_id(s
->manager
);
220 r
= hashmap_put(s
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
), t
);
226 r
= hashmap_replace(s
->transactions_by_key
, t
->key
, t
);
228 hashmap_remove(s
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
));
232 LIST_PREPEND(transactions_by_scope
, s
->transactions
, t
);
235 s
->manager
->n_transactions_total
++;
245 static void dns_transaction_shuffle_id(DnsTransaction
*t
) {
249 /* Pick a new ID for this transaction. */
251 new_id
= pick_new_id(t
->scope
->manager
);
252 assert_se(hashmap_remove_and_put(t
->scope
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
), UINT_TO_PTR(new_id
), t
) >= 0);
254 log_debug("Transaction %" PRIu16
" is now %" PRIu16
".", t
->id
, new_id
);
257 /* Make sure we generate a new packet with the new ID */
258 t
->sent
= dns_packet_unref(t
->sent
);
261 static void dns_transaction_tentative(DnsTransaction
*t
, DnsPacket
*p
) {
262 _cleanup_free_
char *pretty
= NULL
;
263 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
269 if (manager_our_packet(t
->scope
->manager
, p
) != 0)
272 (void) in_addr_to_string(p
->family
, &p
->sender
, &pretty
);
274 log_debug("Transaction %" PRIu16
" for <%s> on scope %s on %s/%s got tentative packet from %s.",
276 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
277 dns_protocol_to_string(t
->scope
->protocol
),
278 t
->scope
->link
? t
->scope
->link
->name
: "*",
279 af_to_name_short(t
->scope
->family
),
282 /* RFC 4795, Section 4.1 says that the peer with the
283 * lexicographically smaller IP address loses */
284 if (memcmp(&p
->sender
, &p
->destination
, FAMILY_ADDRESS_SIZE(p
->family
)) >= 0) {
285 log_debug("Peer has lexicographically larger IP address and thus lost in the conflict.");
289 log_debug("We have the lexicographically larger IP address and thus lost in the conflict.");
293 while ((z
= set_first(t
->notify_zone_items
))) {
294 /* First, make sure the zone item drops the reference
296 dns_zone_item_probe_stop(z
);
298 /* Secondly, report this as conflict, so that we might
299 * look for a different hostname */
300 dns_zone_item_conflict(z
);
304 dns_transaction_gc(t
);
307 void dns_transaction_complete(DnsTransaction
*t
, DnsTransactionState state
) {
308 DnsQueryCandidate
*c
;
312 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
315 assert(!DNS_TRANSACTION_IS_LIVE(state
));
317 if (state
== DNS_TRANSACTION_DNSSEC_FAILED
) {
318 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
);
320 log_struct(LOG_NOTICE
,
321 LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_FAILURE
),
322 LOG_MESSAGE("DNSSEC validation failed for question %s: %s", key_str
, dnssec_result_to_string(t
->answer_dnssec_result
)),
323 "DNS_TRANSACTION=%" PRIu16
, t
->id
,
324 "DNS_QUESTION=%s", key_str
,
325 "DNSSEC_RESULT=%s", dnssec_result_to_string(t
->answer_dnssec_result
),
326 "DNS_SERVER=%s", dns_server_string(t
->server
),
327 "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t
->server
->possible_feature_level
),
331 /* Note that this call might invalidate the query. Callers
332 * should hence not attempt to access the query or transaction
333 * after calling this function. */
335 if (state
== DNS_TRANSACTION_ERRNO
)
336 st
= errno_to_name(t
->answer_errno
);
338 st
= dns_transaction_state_to_string(state
);
340 log_debug("Transaction %" PRIu16
" for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s).",
342 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
343 dns_protocol_to_string(t
->scope
->protocol
),
344 t
->scope
->link
? t
->scope
->link
->name
: "*",
345 af_to_name_short(t
->scope
->family
),
347 t
->answer_source
< 0 ? "none" : dns_transaction_source_to_string(t
->answer_source
),
348 t
->answer_authenticated
? "authenticated" : "unsigned");
352 dns_transaction_close_connection(t
);
353 dns_transaction_stop_timeout(t
);
355 /* Notify all queries that are interested, but make sure the
356 * transaction isn't freed while we are still looking at it */
359 SET_FOREACH_MOVE(c
, t
->notify_query_candidates_done
, t
->notify_query_candidates
)
360 dns_query_candidate_notify(c
);
361 SWAP_TWO(t
->notify_query_candidates
, t
->notify_query_candidates_done
);
363 SET_FOREACH_MOVE(z
, t
->notify_zone_items_done
, t
->notify_zone_items
)
364 dns_zone_item_notify(z
);
365 SWAP_TWO(t
->notify_zone_items
, t
->notify_zone_items_done
);
367 (void) dns_scope_announce(t
->scope
, false);
369 SET_FOREACH_MOVE(d
, t
->notify_transactions_done
, t
->notify_transactions
)
370 dns_transaction_notify(d
, t
);
371 SWAP_TWO(t
->notify_transactions
, t
->notify_transactions_done
);
374 dns_transaction_gc(t
);
377 static int dns_transaction_pick_server(DnsTransaction
*t
) {
381 assert(t
->scope
->protocol
== DNS_PROTOCOL_DNS
);
383 /* Pick a DNS server and a feature level for it. */
385 server
= dns_scope_get_dns_server(t
->scope
);
389 /* If we changed the server invalidate the feature level clamping, as the new server might have completely
390 * different properties. */
391 if (server
!= t
->server
)
392 t
->clamp_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
394 t
->current_feature_level
= dns_server_possible_feature_level(server
);
396 /* Clamp the feature level if that is requested. */
397 if (t
->clamp_feature_level
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
&&
398 t
->current_feature_level
> t
->clamp_feature_level
)
399 t
->current_feature_level
= t
->clamp_feature_level
;
401 log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t
->current_feature_level
), t
->id
);
403 if (server
== t
->server
)
406 dns_server_unref(t
->server
);
407 t
->server
= dns_server_ref(server
);
409 log_debug("Using DNS server %s for transaction %u.", dns_server_string(t
->server
), t
->id
);
414 static void dns_transaction_retry(DnsTransaction
*t
, bool next_server
) {
419 log_debug("Retrying transaction %" PRIu16
".", t
->id
);
421 /* Before we try again, switch to a new server. */
423 dns_scope_next_dns_server(t
->scope
);
425 r
= dns_transaction_go(t
);
427 t
->answer_errno
= -r
;
428 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
432 static int dns_transaction_maybe_restart(DnsTransaction
*t
) {
437 /* Returns > 0 if the transaction was restarted, 0 if not */
442 if (t
->current_feature_level
<= dns_server_possible_feature_level(t
->server
))
445 /* The server's current feature level is lower than when we sent the original query. We learnt something from
446 the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to
447 restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include
448 OPT RR or DO bit. One of these cases is documented here, for example:
449 https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
451 log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
452 dns_transaction_shuffle_id(t
);
454 r
= dns_transaction_go(t
);
461 static int on_stream_complete(DnsStream
*s
, int error
) {
462 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
466 assert(s
->transaction
);
468 /* Copy the data we care about out of the stream before we
471 p
= dns_packet_ref(s
->read_packet
);
473 dns_transaction_close_connection(t
);
475 if (ERRNO_IS_DISCONNECT(error
)) {
478 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
) {
479 /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the
480 * question on this scope. */
481 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
485 log_debug_errno(error
, "Connection failure for DNS TCP stream: %m");
486 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
487 dns_server_packet_lost(t
->server
, IPPROTO_TCP
, t
->current_feature_level
, usec
- t
->start_usec
);
489 dns_transaction_retry(t
, true);
493 t
->answer_errno
= error
;
494 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
498 if (dns_packet_validate_reply(p
) <= 0) {
499 log_debug("Invalid TCP reply packet.");
500 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
504 dns_scope_check_conflicts(t
->scope
, p
);
507 dns_transaction_process_reply(t
, p
);
510 /* If the response wasn't useful, then complete the transition
511 * now. After all, we are the worst feature set now with TCP
512 * sockets, and there's really no point in retrying. */
513 if (t
->state
== DNS_TRANSACTION_PENDING
)
514 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
516 dns_transaction_gc(t
);
521 static int dns_transaction_open_tcp(DnsTransaction
*t
) {
522 _cleanup_close_
int fd
= -1;
527 dns_transaction_close_connection(t
);
529 switch (t
->scope
->protocol
) {
531 case DNS_PROTOCOL_DNS
:
532 r
= dns_transaction_pick_server(t
);
536 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
539 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
543 fd
= dns_scope_socket_tcp(t
->scope
, AF_UNSPEC
, NULL
, t
->server
, 53);
546 case DNS_PROTOCOL_LLMNR
:
547 /* When we already received a reply to this (but it was truncated), send to its sender address */
549 fd
= dns_scope_socket_tcp(t
->scope
, t
->received
->family
, &t
->received
->sender
, NULL
, t
->received
->sender_port
);
551 union in_addr_union address
;
552 int family
= AF_UNSPEC
;
554 /* Otherwise, try to talk to the owner of a
555 * the IP address, in case this is a reverse
558 r
= dns_name_address(dns_resource_key_name(t
->key
), &family
, &address
);
563 if (family
!= t
->scope
->family
)
566 fd
= dns_scope_socket_tcp(t
->scope
, family
, &address
, NULL
, LLMNR_PORT
);
572 return -EAFNOSUPPORT
;
578 r
= dns_stream_new(t
->scope
->manager
, &t
->stream
, t
->scope
->protocol
, fd
);
583 r
= dns_stream_write_packet(t
->stream
, t
->sent
);
585 t
->stream
= dns_stream_unref(t
->stream
);
589 t
->stream
->complete
= on_stream_complete
;
590 t
->stream
->transaction
= t
;
592 /* The interface index is difficult to determine if we are
593 * connecting to the local host, hence fill this in right away
594 * instead of determining it from the socket */
595 t
->stream
->ifindex
= dns_scope_ifindex(t
->scope
);
597 dns_transaction_reset_answer(t
);
599 t
->tried_stream
= true;
604 static void dns_transaction_cache_answer(DnsTransaction
*t
) {
607 /* For mDNS we cache whenever we get the packet, rather than
608 * in each transaction. */
609 if (!IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
))
612 /* Caching disabled? */
613 if (!t
->scope
->manager
->enable_cache
)
616 /* We never cache if this packet is from the local host, under
617 * the assumption that a locally running DNS server would
618 * cache this anyway, and probably knows better when to flush
619 * the cache then we could. */
620 if (!DNS_PACKET_SHALL_CACHE(t
->received
))
623 dns_cache_put(&t
->scope
->cache
,
627 t
->answer_authenticated
,
631 &t
->received
->sender
);
634 static bool dns_transaction_dnssec_is_live(DnsTransaction
*t
) {
640 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
641 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
647 static int dns_transaction_dnssec_ready(DnsTransaction
*t
) {
653 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
654 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
656 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
660 case DNS_TRANSACTION_NULL
:
661 case DNS_TRANSACTION_PENDING
:
662 case DNS_TRANSACTION_VALIDATING
:
666 case DNS_TRANSACTION_RCODE_FAILURE
:
667 if (!IN_SET(dt
->answer_rcode
, DNS_RCODE_NXDOMAIN
, DNS_RCODE_SERVFAIL
)) {
668 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt
->answer_rcode
));
672 /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers
673 * erronously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS
674 * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar
675 * RRs to make unsigned proofs. */
677 case DNS_TRANSACTION_SUCCESS
:
681 case DNS_TRANSACTION_DNSSEC_FAILED
:
682 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
683 * validationr result */
685 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt
->answer_dnssec_result
));
686 t
->answer_dnssec_result
= dt
->answer_dnssec_result
; /* Copy error code over */
687 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
692 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt
->state
));
697 /* All is ready, we can go and validate */
701 t
->answer_dnssec_result
= DNSSEC_FAILED_AUXILIARY
;
702 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
706 static void dns_transaction_process_dnssec(DnsTransaction
*t
) {
711 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
712 r
= dns_transaction_dnssec_ready(t
);
715 if (r
== 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
718 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
719 * restart the lookup immediately. */
720 r
= dns_transaction_maybe_restart(t
);
723 if (r
> 0) /* Transaction got restarted... */
726 /* All our auxiliary DNSSEC transactions are complete now. Try
727 * to validate our RRset now. */
728 r
= dns_transaction_validate_dnssec(t
);
730 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
736 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
&&
737 t
->scope
->dnssec_mode
== DNSSEC_YES
) {
738 /* We are not in automatic downgrade mode, and the
739 * server is bad, refuse operation. */
740 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
744 if (!IN_SET(t
->answer_dnssec_result
,
745 _DNSSEC_RESULT_INVALID
, /* No DNSSEC validation enabled */
746 DNSSEC_VALIDATED
, /* Answer is signed and validated successfully */
747 DNSSEC_UNSIGNED
, /* Answer is right-fully unsigned */
748 DNSSEC_INCOMPATIBLE_SERVER
)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
749 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
753 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
)
754 dns_server_warn_downgrade(t
->server
);
756 dns_transaction_cache_answer(t
);
758 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
759 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
761 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
766 t
->answer_errno
= -r
;
767 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
770 static int dns_transaction_has_positive_answer(DnsTransaction
*t
, DnsAnswerFlags
*flags
) {
775 /* Checks whether the answer is positive, i.e. either a direct
776 * answer to the question, or a CNAME/DNAME for it */
778 r
= dns_answer_match_key(t
->answer
, t
->key
, flags
);
782 r
= dns_answer_find_cname_or_dname(t
->answer
, t
->key
, NULL
, flags
);
789 static int dns_transaction_fix_rcode(DnsTransaction
*t
) {
794 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
795 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
796 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
797 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
798 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
799 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
800 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
801 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
802 * incomplete CNAME/DNAME chain.
804 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
805 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
808 if (t
->answer_rcode
!= DNS_RCODE_NXDOMAIN
)
811 r
= dns_transaction_has_positive_answer(t
, NULL
);
815 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
819 void dns_transaction_process_reply(DnsTransaction
*t
, DnsPacket
*p
) {
826 assert(t
->scope
->manager
);
828 if (t
->state
!= DNS_TRANSACTION_PENDING
)
831 /* Note that this call might invalidate the query. Callers
832 * should hence not attempt to access the query or transaction
833 * after calling this function. */
835 log_debug("Processing incoming packet on transaction %" PRIu16
".", t
->id
);
837 switch (t
->scope
->protocol
) {
839 case DNS_PROTOCOL_LLMNR
:
840 /* For LLMNR we will not accept any packets from other interfaces */
842 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
845 if (p
->family
!= t
->scope
->family
)
848 /* Tentative packets are not full responses but still
849 * useful for identifying uniqueness conflicts during
851 if (DNS_PACKET_LLMNR_T(p
)) {
852 dns_transaction_tentative(t
, p
);
858 case DNS_PROTOCOL_MDNS
:
859 /* For mDNS we will not accept any packets from other interfaces */
861 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
864 if (p
->family
!= t
->scope
->family
)
869 case DNS_PROTOCOL_DNS
:
870 /* Note that we do not need to verify the
871 * addresses/port numbers of incoming traffic, as we
872 * invoked connect() on our UDP socket in which case
873 * the kernel already does the needed verification for
878 assert_not_reached("Invalid DNS protocol.");
881 if (t
->received
!= p
) {
882 dns_packet_unref(t
->received
);
883 t
->received
= dns_packet_ref(p
);
886 t
->answer_source
= DNS_TRANSACTION_NETWORK
;
888 if (p
->ipproto
== IPPROTO_TCP
) {
889 if (DNS_PACKET_TC(p
)) {
890 /* Truncated via TCP? Somebody must be fucking with us */
891 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
895 if (DNS_PACKET_ID(p
) != t
->id
) {
896 /* Not the reply to our query? Somebody must be fucking with us */
897 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
902 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
904 switch (t
->scope
->protocol
) {
906 case DNS_PROTOCOL_DNS
:
909 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_FORMERR
, DNS_RCODE_SERVFAIL
, DNS_RCODE_NOTIMP
)) {
911 /* Request failed, immediately try again with reduced features */
913 if (t
->current_feature_level
<= DNS_SERVER_FEATURE_LEVEL_WORST
) {
914 /* This was already at the lowest possible feature level? If so, we can't downgrade
915 * this transaction anymore, hence let's process the response, and accept the rcode. */
916 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
920 /* Reduce this feature level by one and try again. */
921 t
->clamp_feature_level
= t
->current_feature_level
- 1;
923 log_debug("Server returned error %s, retrying transaction with reduced feature level %s.",
924 dns_rcode_to_string(DNS_PACKET_RCODE(p
)),
925 dns_server_feature_level_to_string(t
->clamp_feature_level
));
927 dns_transaction_retry(t
, false /* use the same server */);
931 if (DNS_PACKET_RCODE(p
) == DNS_RCODE_REFUSED
) {
932 /* This server refused our request? If so, try again, use a different server */
933 log_debug("Server returned REFUSED, switching servers, and retrying.");
934 dns_transaction_retry(t
, true /* pick a new server */);
938 if (DNS_PACKET_TC(p
))
939 dns_server_packet_truncated(t
->server
, t
->current_feature_level
);
943 case DNS_PROTOCOL_LLMNR
:
944 case DNS_PROTOCOL_MDNS
:
945 dns_scope_packet_received(t
->scope
, ts
- t
->start_usec
);
949 assert_not_reached("Invalid DNS protocol.");
952 if (DNS_PACKET_TC(p
)) {
954 /* Truncated packets for mDNS are not allowed. Give up immediately. */
955 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
) {
956 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
960 log_debug("Reply truncated, retrying via TCP.");
962 /* Response was truncated, let's try again with good old TCP */
963 r
= dns_transaction_open_tcp(t
);
965 /* No servers found? Damn! */
966 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
969 if (r
== -EOPNOTSUPP
) {
970 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
971 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
975 /* On LLMNR, if we cannot connect to the host,
976 * we immediately give up */
977 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
980 /* On DNS, couldn't send? Try immediately again, with a new server */
981 dns_transaction_retry(t
, true);
987 /* After the superficial checks, actually parse the message. */
988 r
= dns_packet_extract(p
);
990 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
995 /* Report that we successfully received a valid packet with a good rcode after we initially got a bad
996 * rcode and subsequently downgraded the protocol */
998 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_SUCCESS
, DNS_RCODE_NXDOMAIN
) &&
999 t
->clamp_feature_level
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
)
1000 dns_server_packet_rcode_downgrade(t
->server
, t
->clamp_feature_level
);
1002 /* Report that the OPT RR was missing */
1004 dns_server_packet_bad_opt(t
->server
, t
->current_feature_level
);
1006 /* Report that we successfully received a packet */
1007 dns_server_packet_received(t
->server
, p
->ipproto
, t
->current_feature_level
, ts
- t
->start_usec
, p
->size
);
1010 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
1011 r
= dns_transaction_maybe_restart(t
);
1014 if (r
> 0) /* Transaction got restarted... */
1017 if (IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
, DNS_PROTOCOL_MDNS
)) {
1019 /* When dealing with protocols other than mDNS only consider responses with
1020 * equivalent query section to the request. For mDNS this check doesn't make
1021 * sense, because the section 6 of RFC6762 states that "Multicast DNS responses MUST NOT
1022 * contain any questions in the Question Section". */
1023 if (t
->scope
->protocol
!= DNS_PROTOCOL_MDNS
) {
1024 r
= dns_packet_is_reply_for(p
, t
->key
);
1028 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1033 /* Install the answer as answer to the transaction */
1034 dns_answer_unref(t
->answer
);
1035 t
->answer
= dns_answer_ref(p
->answer
);
1036 t
->answer_rcode
= DNS_PACKET_RCODE(p
);
1037 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
1038 t
->answer_authenticated
= false;
1040 r
= dns_transaction_fix_rcode(t
);
1044 /* Block GC while starting requests for additional DNSSEC RRs */
1046 r
= dns_transaction_request_dnssec_keys(t
);
1049 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
1050 if (!dns_transaction_gc(t
))
1053 /* Requesting additional keys might have resulted in
1054 * this transaction to fail, since the auxiliary
1055 * request failed for some reason. If so, we are not
1056 * in pending state anymore, and we should exit
1058 if (t
->state
!= DNS_TRANSACTION_PENDING
)
1063 /* There are DNSSEC transactions pending now. Update the state accordingly. */
1064 t
->state
= DNS_TRANSACTION_VALIDATING
;
1065 dns_transaction_close_connection(t
);
1066 dns_transaction_stop_timeout(t
);
1071 dns_transaction_process_dnssec(t
);
1075 t
->answer_errno
= -r
;
1076 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1079 static int on_dns_packet(sd_event_source
*s
, int fd
, uint32_t revents
, void *userdata
) {
1080 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1081 DnsTransaction
*t
= userdata
;
1087 r
= manager_recv(t
->scope
->manager
, fd
, DNS_PROTOCOL_DNS
, &p
);
1088 if (ERRNO_IS_DISCONNECT(-r
)) {
1091 /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next
1092 * recvmsg(). Treat this like a lost packet. */
1094 log_debug_errno(r
, "Connection failure for DNS UDP packet: %m");
1095 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
1096 dns_server_packet_lost(t
->server
, IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1098 dns_transaction_retry(t
, true);
1102 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1103 t
->answer_errno
= -r
;
1107 r
= dns_packet_validate_reply(p
);
1109 log_debug_errno(r
, "Received invalid DNS packet as response, ignoring: %m");
1113 log_debug("Received inappropriate DNS packet as response, ignoring.");
1117 if (DNS_PACKET_ID(p
) != t
->id
) {
1118 log_debug("Received packet with incorrect transaction ID, ignoring.");
1122 dns_transaction_process_reply(t
, p
);
1126 static int dns_transaction_emit_udp(DnsTransaction
*t
) {
1131 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1133 r
= dns_transaction_pick_server(t
);
1137 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_UDP
)
1140 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
1143 if (r
> 0 || t
->dns_udp_fd
< 0) { /* Server changed, or no connection yet. */
1146 dns_transaction_close_connection(t
);
1148 fd
= dns_scope_socket_udp(t
->scope
, t
->server
, 53);
1152 r
= sd_event_add_io(t
->scope
->manager
->event
, &t
->dns_udp_event_source
, fd
, EPOLLIN
, on_dns_packet
, t
);
1158 (void) sd_event_source_set_description(t
->dns_udp_event_source
, "dns-transaction-udp");
1162 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
1166 dns_transaction_close_connection(t
);
1168 r
= dns_scope_emit_udp(t
->scope
, t
->dns_udp_fd
, t
->sent
);
1172 dns_transaction_reset_answer(t
);
1177 static int on_transaction_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1178 DnsTransaction
*t
= userdata
;
1183 if (!t
->initial_jitter_scheduled
|| t
->initial_jitter_elapsed
) {
1184 /* Timeout reached? Increase the timeout for the server used */
1185 switch (t
->scope
->protocol
) {
1187 case DNS_PROTOCOL_DNS
:
1189 dns_server_packet_lost(t
->server
, t
->stream
? IPPROTO_TCP
: IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1192 case DNS_PROTOCOL_LLMNR
:
1193 case DNS_PROTOCOL_MDNS
:
1194 dns_scope_packet_lost(t
->scope
, usec
- t
->start_usec
);
1198 assert_not_reached("Invalid DNS protocol.");
1201 if (t
->initial_jitter_scheduled
)
1202 t
->initial_jitter_elapsed
= true;
1205 log_debug("Timeout reached on transaction %" PRIu16
".", t
->id
);
1207 dns_transaction_retry(t
, true);
1211 static usec_t
transaction_get_resend_timeout(DnsTransaction
*t
) {
1215 switch (t
->scope
->protocol
) {
1217 case DNS_PROTOCOL_DNS
:
1219 return t
->server
->resend_timeout
;
1221 case DNS_PROTOCOL_MDNS
:
1222 assert(t
->n_attempts
> 0);
1224 return MDNS_PROBING_INTERVAL_USEC
;
1226 return (1 << (t
->n_attempts
- 1)) * USEC_PER_SEC
;
1228 case DNS_PROTOCOL_LLMNR
:
1229 return t
->scope
->resend_timeout
;
1232 assert_not_reached("Invalid DNS protocol.");
1236 static int dns_transaction_prepare(DnsTransaction
*t
, usec_t ts
) {
1241 dns_transaction_stop_timeout(t
);
1243 r
= dns_scope_network_good(t
->scope
);
1247 dns_transaction_complete(t
, DNS_TRANSACTION_NETWORK_DOWN
);
1251 if (t
->n_attempts
>= TRANSACTION_ATTEMPTS_MAX(t
->scope
->protocol
)) {
1252 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1256 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& t
->tried_stream
) {
1257 /* If we already tried via a stream, then we don't
1258 * retry on LLMNR. See RFC 4795, Section 2.7. */
1259 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1266 dns_transaction_reset_answer(t
);
1267 dns_transaction_flush_dnssec_transactions(t
);
1269 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1270 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1271 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, t
->key
, &t
->answer
);
1275 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1276 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1277 t
->answer_authenticated
= true;
1278 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1282 if (dns_name_is_root(dns_resource_key_name(t
->key
)) &&
1283 t
->key
->type
== DNS_TYPE_DS
) {
1285 /* Hmm, this is a request for the root DS? A
1286 * DS RR doesn't exist in the root zone, and
1287 * if our trust anchor didn't know it either,
1288 * this means we cannot do any DNSSEC logic
1291 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
1292 /* We are in downgrade mode. In this
1293 * case, synthesize an unsigned empty
1294 * response, so that the any lookup
1295 * depending on this one can continue
1296 * assuming there was no DS, and hence
1297 * the root zone was unsigned. */
1299 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1300 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1301 t
->answer_authenticated
= false;
1302 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1304 /* If we are not in downgrade mode,
1305 * then fail the lookup, because we
1306 * cannot reasonably answer it. There
1307 * might be DS RRs, but we don't know
1308 * them, and the DNS server won't tell
1309 * them to us (and even if it would,
1310 * we couldn't validate and trust them. */
1311 dns_transaction_complete(t
, DNS_TRANSACTION_NO_TRUST_ANCHOR
);
1317 /* Check the zone, but only if this transaction is not used
1318 * for probing or verifying a zone item. */
1319 if (set_isempty(t
->notify_zone_items
)) {
1321 r
= dns_zone_lookup(&t
->scope
->zone
, t
->key
, dns_scope_ifindex(t
->scope
), &t
->answer
, NULL
, NULL
);
1325 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1326 t
->answer_source
= DNS_TRANSACTION_ZONE
;
1327 t
->answer_authenticated
= true;
1328 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1333 /* Check the cache, but only if this transaction is not used
1334 * for probing or verifying a zone item. */
1335 if (set_isempty(t
->notify_zone_items
)) {
1337 /* Before trying the cache, let's make sure we figured out a
1338 * server to use. Should this cause a change of server this
1339 * might flush the cache. */
1340 dns_scope_get_dns_server(t
->scope
);
1342 /* Let's then prune all outdated entries */
1343 dns_cache_prune(&t
->scope
->cache
);
1345 r
= dns_cache_lookup(&t
->scope
->cache
, t
->key
, t
->clamp_ttl
, &t
->answer_rcode
, &t
->answer
, &t
->answer_authenticated
);
1349 t
->answer_source
= DNS_TRANSACTION_CACHE
;
1350 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
1351 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1353 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
1361 static int dns_transaction_make_packet_mdns(DnsTransaction
*t
) {
1363 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1364 bool add_known_answers
= false;
1365 DnsTransaction
*other
;
1371 assert(t
->scope
->protocol
== DNS_PROTOCOL_MDNS
);
1373 /* Discard any previously prepared packet, so we can start over and coalesce again */
1374 t
->sent
= dns_packet_unref(t
->sent
);
1376 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, false);
1380 r
= dns_packet_append_key(p
, t
->key
, 0, NULL
);
1386 if (dns_key_is_shared(t
->key
))
1387 add_known_answers
= true;
1390 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1391 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1392 * in our current scope, and see whether their timing contraints allow them to be sent.
1395 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1397 LIST_FOREACH(transactions_by_scope
, other
, t
->scope
->transactions
) {
1399 /* Skip ourselves */
1403 if (other
->state
!= DNS_TRANSACTION_PENDING
)
1406 if (other
->next_attempt_after
> ts
)
1409 if (qdcount
>= UINT16_MAX
)
1412 r
= dns_packet_append_key(p
, other
->key
, 0, NULL
);
1415 * If we can't stuff more questions into the packet, just give up.
1416 * One of the 'other' transactions will fire later and take care of the rest.
1424 r
= dns_transaction_prepare(other
, ts
);
1428 ts
+= transaction_get_resend_timeout(other
);
1430 r
= sd_event_add_time(
1431 other
->scope
->manager
->event
,
1432 &other
->timeout_event_source
,
1433 clock_boottime_or_monotonic(),
1435 on_transaction_timeout
, other
);
1439 (void) sd_event_source_set_description(other
->timeout_event_source
, "dns-transaction-timeout");
1441 other
->state
= DNS_TRANSACTION_PENDING
;
1442 other
->next_attempt_after
= ts
;
1446 if (dns_key_is_shared(other
->key
))
1447 add_known_answers
= true;
1450 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(qdcount
);
1452 /* Append known answer section if we're asking for any shared record */
1453 if (add_known_answers
) {
1454 r
= dns_cache_export_shared_to_packet(&t
->scope
->cache
, p
);
1465 static int dns_transaction_make_packet(DnsTransaction
*t
) {
1466 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1471 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)
1472 return dns_transaction_make_packet_mdns(t
);
1477 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, t
->scope
->dnssec_mode
!= DNSSEC_NO
);
1481 r
= dns_packet_append_key(p
, t
->key
, 0, NULL
);
1485 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
1486 DNS_PACKET_HEADER(p
)->id
= t
->id
;
1494 int dns_transaction_go(DnsTransaction
*t
) {
1497 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1501 /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has finished
1504 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1506 r
= dns_transaction_prepare(t
, ts
);
1510 log_debug("Transaction %" PRIu16
" for <%s> scope %s on %s/%s.",
1512 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
1513 dns_protocol_to_string(t
->scope
->protocol
),
1514 t
->scope
->link
? t
->scope
->link
->name
: "*",
1515 af_to_name_short(t
->scope
->family
));
1517 if (!t
->initial_jitter_scheduled
&&
1518 (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
||
1519 t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)) {
1520 usec_t jitter
, accuracy
;
1522 /* RFC 4795 Section 2.7 suggests all queries should be
1523 * delayed by a random time from 0 to JITTER_INTERVAL. */
1525 t
->initial_jitter_scheduled
= true;
1527 random_bytes(&jitter
, sizeof(jitter
));
1529 switch (t
->scope
->protocol
) {
1531 case DNS_PROTOCOL_LLMNR
:
1532 jitter
%= LLMNR_JITTER_INTERVAL_USEC
;
1533 accuracy
= LLMNR_JITTER_INTERVAL_USEC
;
1536 case DNS_PROTOCOL_MDNS
:
1537 jitter
%= MDNS_JITTER_RANGE_USEC
;
1538 jitter
+= MDNS_JITTER_MIN_USEC
;
1539 accuracy
= MDNS_JITTER_RANGE_USEC
;
1542 assert_not_reached("bad protocol");
1545 r
= sd_event_add_time(
1546 t
->scope
->manager
->event
,
1547 &t
->timeout_event_source
,
1548 clock_boottime_or_monotonic(),
1549 ts
+ jitter
, accuracy
,
1550 on_transaction_timeout
, t
);
1554 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1557 t
->next_attempt_after
= ts
;
1558 t
->state
= DNS_TRANSACTION_PENDING
;
1560 log_debug("Delaying %s transaction for " USEC_FMT
"us.", dns_protocol_to_string(t
->scope
->protocol
), jitter
);
1564 /* Otherwise, we need to ask the network */
1565 r
= dns_transaction_make_packet(t
);
1569 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&&
1570 (dns_name_endswith(dns_resource_key_name(t
->key
), "in-addr.arpa") > 0 ||
1571 dns_name_endswith(dns_resource_key_name(t
->key
), "ip6.arpa") > 0)) {
1573 /* RFC 4795, Section 2.4. says reverse lookups shall
1574 * always be made via TCP on LLMNR */
1575 r
= dns_transaction_open_tcp(t
);
1577 /* Try via UDP, and if that fails due to large size or lack of
1578 * support try via TCP */
1579 r
= dns_transaction_emit_udp(t
);
1581 log_debug("Sending query via TCP since it is too large.");
1583 log_debug("Sending query via TCP since server doesn't support UDP.");
1584 if (r
== -EMSGSIZE
|| r
== -EAGAIN
)
1585 r
= dns_transaction_open_tcp(t
);
1589 /* No servers to send this to? */
1590 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
1593 if (r
== -EOPNOTSUPP
) {
1594 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1595 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
1598 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& ERRNO_IS_DISCONNECT(-r
)) {
1599 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
1600 * answer this request with this protocol. */
1601 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
1605 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1608 /* Couldn't send? Try immediately again, with a new server */
1609 dns_scope_next_dns_server(t
->scope
);
1611 return dns_transaction_go(t
);
1614 ts
+= transaction_get_resend_timeout(t
);
1616 r
= sd_event_add_time(
1617 t
->scope
->manager
->event
,
1618 &t
->timeout_event_source
,
1619 clock_boottime_or_monotonic(),
1621 on_transaction_timeout
, t
);
1625 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1627 t
->state
= DNS_TRANSACTION_PENDING
;
1628 t
->next_attempt_after
= ts
;
1633 static int dns_transaction_find_cyclic(DnsTransaction
*t
, DnsTransaction
*aux
) {
1641 /* Try to find cyclic dependencies between transaction objects */
1646 SET_FOREACH(n
, aux
->dnssec_transactions
, i
) {
1647 r
= dns_transaction_find_cyclic(t
, n
);
1655 static int dns_transaction_add_dnssec_transaction(DnsTransaction
*t
, DnsResourceKey
*key
, DnsTransaction
**ret
) {
1656 DnsTransaction
*aux
;
1663 aux
= dns_scope_find_transaction(t
->scope
, key
, true);
1665 r
= dns_transaction_new(&aux
, t
->scope
, key
);
1669 if (set_contains(t
->dnssec_transactions
, aux
)) {
1674 r
= dns_transaction_find_cyclic(t
, aux
);
1678 char s
[DNS_RESOURCE_KEY_STRING_MAX
], saux
[DNS_RESOURCE_KEY_STRING_MAX
];
1680 log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16
" (%s) as dependency for %" PRIu16
" (%s).",
1682 dns_resource_key_to_string(t
->key
, s
, sizeof s
),
1684 dns_resource_key_to_string(aux
->key
, saux
, sizeof saux
));
1690 r
= set_ensure_allocated(&t
->dnssec_transactions
, NULL
);
1694 r
= set_ensure_allocated(&aux
->notify_transactions
, NULL
);
1698 r
= set_ensure_allocated(&aux
->notify_transactions_done
, NULL
);
1702 r
= set_put(t
->dnssec_transactions
, aux
);
1706 r
= set_put(aux
->notify_transactions
, t
);
1708 (void) set_remove(t
->dnssec_transactions
, aux
);
1716 dns_transaction_gc(aux
);
1720 static int dns_transaction_request_dnssec_rr(DnsTransaction
*t
, DnsResourceKey
*key
) {
1721 _cleanup_(dns_answer_unrefp
) DnsAnswer
*a
= NULL
;
1722 DnsTransaction
*aux
;
1728 /* Try to get the data from the trust anchor */
1729 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, key
, &a
);
1733 r
= dns_answer_extend(&t
->validated_keys
, a
);
1740 /* This didn't work, ask for it via the network/cache then. */
1741 r
= dns_transaction_add_dnssec_transaction(t
, key
, &aux
);
1742 if (r
== -ELOOP
) /* This would result in a cyclic dependency */
1747 if (aux
->state
== DNS_TRANSACTION_NULL
) {
1748 r
= dns_transaction_go(aux
);
1756 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction
*t
, const char *name
) {
1761 /* Check whether the specified name is in the NTA
1762 * database, either in the global one, or the link-local
1765 r
= dns_trust_anchor_lookup_negative(&t
->scope
->manager
->trust_anchor
, name
);
1769 if (!t
->scope
->link
)
1772 return set_contains(t
->scope
->link
->dnssec_negative_trust_anchors
, name
);
1775 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction
*t
) {
1780 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
1781 * RRs to prove it */
1783 r
= dns_transaction_has_positive_answer(t
, NULL
);
1789 /* Is this key explicitly listed as a negative trust anchor?
1790 * If so, it's nothing we need to care about */
1791 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
1797 /* The answer does not contain any RRs that match to the
1798 * question. If so, let's see if there are any NSEC/NSEC3 RRs
1799 * included. If not, the answer is unsigned. */
1801 r
= dns_answer_contains_nsec_or_nsec3(t
->answer
);
1810 static int dns_transaction_is_primary_response(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
1816 /* Check if the specified RR is the "primary" response,
1817 * i.e. either matches the question precisely or is a
1818 * CNAME/DNAME for it. */
1820 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1824 return dns_resource_key_match_cname_or_dname(t
->key
, rr
->key
, NULL
);
1827 static bool dns_transaction_dnssec_supported(DnsTransaction
*t
) {
1830 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
1831 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
1833 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1836 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
1837 * be supported, hence return true. */
1841 /* Note that we do not check the feature level actually used for the transaction but instead the feature level
1842 * the server is known to support currently, as the transaction feature level might be lower than what the
1843 * server actually supports, since we might have downgraded this transaction's feature level because we got a
1844 * SERVFAIL earlier and wanted to check whether downgrading fixes it. */
1846 return dns_server_dnssec_supported(t
->server
);
1849 static bool dns_transaction_dnssec_supported_full(DnsTransaction
*t
) {
1855 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
1857 if (!dns_transaction_dnssec_supported(t
))
1860 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
1861 if (!dns_transaction_dnssec_supported(dt
))
1867 int dns_transaction_request_dnssec_keys(DnsTransaction
*t
) {
1868 DnsResourceRecord
*rr
;
1875 * Retrieve all auxiliary RRs for the answer we got, so that
1876 * we can verify signatures or prove that RRs are rightfully
1877 * unsigned. Specifically:
1879 * - For RRSIG we get the matching DNSKEY
1880 * - For DNSKEY we get the matching DS
1881 * - For unsigned SOA/NS we get the matching DS
1882 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
1883 * - For other unsigned RRs we get the matching SOA RR
1884 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
1885 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
1886 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
1889 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
1891 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
1892 return 0; /* We only need to validate stuff from the network */
1893 if (!dns_transaction_dnssec_supported(t
))
1894 return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */
1896 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
1898 if (dns_type_is_pseudo(rr
->key
->type
))
1901 /* If this RR is in the negative trust anchor, we don't need to validate it. */
1902 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
1908 switch (rr
->key
->type
) {
1910 case DNS_TYPE_RRSIG
: {
1911 /* For each RRSIG we request the matching DNSKEY */
1912 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*dnskey
= NULL
;
1914 /* If this RRSIG is about a DNSKEY RR and the
1915 * signer is the same as the owner, then we
1916 * already have the DNSKEY, and we don't have
1917 * to look for more. */
1918 if (rr
->rrsig
.type_covered
== DNS_TYPE_DNSKEY
) {
1919 r
= dns_name_equal(rr
->rrsig
.signer
, dns_resource_key_name(rr
->key
));
1926 /* If the signer is not a parent of our
1927 * original query, then this is about an
1928 * auxiliary RRset, but not anything we asked
1929 * for. In this case we aren't interested,
1930 * because we don't want to request additional
1931 * RRs for stuff we didn't really ask for, and
1932 * also to avoid request loops, where
1933 * additional RRs from one transaction result
1934 * in another transaction whose additonal RRs
1935 * point back to the original transaction, and
1937 r
= dns_name_endswith(dns_resource_key_name(t
->key
), rr
->rrsig
.signer
);
1943 dnskey
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DNSKEY
, rr
->rrsig
.signer
);
1947 log_debug("Requesting DNSKEY to validate transaction %" PRIu16
" (%s, RRSIG with key tag: %" PRIu16
").",
1948 t
->id
, dns_resource_key_name(rr
->key
), rr
->rrsig
.key_tag
);
1949 r
= dns_transaction_request_dnssec_rr(t
, dnskey
);
1955 case DNS_TYPE_DNSKEY
: {
1956 /* For each DNSKEY we request the matching DS */
1957 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1959 /* If the DNSKEY we are looking at is not for
1960 * zone we are interested in, nor any of its
1961 * parents, we aren't interested, and don't
1962 * request it. After all, we don't want to end
1963 * up in request loops, and want to keep
1964 * additional traffic down. */
1966 r
= dns_name_endswith(dns_resource_key_name(t
->key
), dns_resource_key_name(rr
->key
));
1972 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
1976 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, DNSKEY with key tag: %" PRIu16
").",
1977 t
->id
, dns_resource_key_name(rr
->key
), dnssec_keytag(rr
, false));
1978 r
= dns_transaction_request_dnssec_rr(t
, ds
);
1987 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1989 /* For an unsigned SOA or NS, try to acquire
1990 * the matching DS RR, as we are at a zone cut
1991 * then, and whether a DS exists tells us
1992 * whether the zone is signed. Do so only if
1993 * this RR matches our original question,
1996 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
2002 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2008 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
2012 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned SOA/NS RRset).",
2013 t
->id
, dns_resource_key_name(rr
->key
));
2014 r
= dns_transaction_request_dnssec_rr(t
, ds
);
2022 case DNS_TYPE_CNAME
:
2023 case DNS_TYPE_DNAME
: {
2024 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2027 /* CNAMEs and DNAMEs cannot be located at a
2028 * zone apex, hence ask for the parent SOA for
2029 * unsigned CNAME/DNAME RRs, maybe that's the
2030 * apex. But do all that only if this is
2031 * actually a response to our original
2034 * Similar for DS RRs, which are signed when
2035 * the parent SOA is signed. */
2037 r
= dns_transaction_is_primary_response(t
, rr
);
2043 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2049 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2055 name
= dns_resource_key_name(rr
->key
);
2056 r
= dns_name_parent(&name
);
2062 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, name
);
2066 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned CNAME/DNAME/DS RRset).",
2067 t
->id
, dns_resource_key_name(rr
->key
));
2068 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2076 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2078 /* For other unsigned RRsets (including
2079 * NSEC/NSEC3!), look for proof the zone is
2080 * unsigned, by requesting the SOA RR of the
2081 * zone. However, do so only if they are
2082 * directly relevant to our original
2085 r
= dns_transaction_is_primary_response(t
, rr
);
2091 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2097 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, dns_resource_key_name(rr
->key
));
2101 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned non-SOA/NS RRset <%s>).",
2102 t
->id
, dns_resource_key_name(rr
->key
), dns_resource_record_to_string(rr
));
2103 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2110 /* Above, we requested everything necessary to validate what
2111 * we got. Now, let's request what we need to validate what we
2114 r
= dns_transaction_has_unsigned_negative_answer(t
);
2121 name
= dns_resource_key_name(t
->key
);
2123 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2124 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2125 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2126 * though they have further children. If this was a DS request, then it's signed when the parent zone
2127 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2128 * to see if that is signed. */
2130 if (t
->key
->type
== DNS_TYPE_DS
) {
2131 r
= dns_name_parent(&name
);
2133 type
= DNS_TYPE_SOA
;
2134 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned empty DS response).",
2135 t
->id
, dns_resource_key_name(t
->key
));
2139 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
)) {
2142 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned empty SOA/NS response).",
2143 t
->id
, dns_resource_key_name(t
->key
));
2146 type
= DNS_TYPE_SOA
;
2147 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned empty non-SOA/NS/DS response).",
2148 t
->id
, dns_resource_key_name(t
->key
));
2152 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2154 soa
= dns_resource_key_new(t
->key
->class, type
, name
);
2158 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2164 return dns_transaction_dnssec_is_live(t
);
2167 void dns_transaction_notify(DnsTransaction
*t
, DnsTransaction
*source
) {
2171 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2172 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2173 the state is VALIDATING however, we should check if we are complete now. */
2175 if (t
->state
== DNS_TRANSACTION_VALIDATING
)
2176 dns_transaction_process_dnssec(t
);
2179 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction
*t
) {
2180 DnsResourceRecord
*rr
;
2185 /* Add all DNSKEY RRs from the answer that are validated by DS
2186 * RRs from the list of validated keys to the list of
2187 * validated keys. */
2189 DNS_ANSWER_FOREACH_IFINDEX(rr
, ifindex
, t
->answer
) {
2191 r
= dnssec_verify_dnskey_by_ds_search(rr
, t
->validated_keys
);
2197 /* If so, the DNSKEY is validated too. */
2198 r
= dns_answer_add_extend(&t
->validated_keys
, rr
, ifindex
, DNS_ANSWER_AUTHENTICATED
);
2206 static int dns_transaction_requires_rrsig(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2212 /* Checks if the RR we are looking for must be signed with an
2213 * RRSIG. This is used for positive responses. */
2215 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2218 if (dns_type_is_pseudo(rr
->key
->type
))
2221 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2227 switch (rr
->key
->type
) {
2229 case DNS_TYPE_RRSIG
:
2230 /* RRSIGs are the signatures themselves, they need no signing. */
2238 /* For SOA or NS RRs we look for a matching DS transaction */
2240 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2242 if (dt
->key
->class != rr
->key
->class)
2244 if (dt
->key
->type
!= DNS_TYPE_DS
)
2247 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2253 /* We found a DS transactions for the SOA/NS
2254 * RRs we are looking at. If it discovered signed DS
2255 * RRs, then we need to be signed, too. */
2257 if (!dt
->answer_authenticated
)
2260 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2263 /* We found nothing that proves this is safe to leave
2264 * this unauthenticated, hence ask inist on
2265 * authentication. */
2270 case DNS_TYPE_CNAME
:
2271 case DNS_TYPE_DNAME
: {
2272 const char *parent
= NULL
;
2277 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2279 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2282 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2284 if (dt
->key
->class != rr
->key
->class)
2286 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2290 parent
= dns_resource_key_name(rr
->key
);
2291 r
= dns_name_parent(&parent
);
2295 if (rr
->key
->type
== DNS_TYPE_DS
)
2298 /* A CNAME/DNAME without a parent? That's sooo weird. */
2299 log_debug("Transaction %" PRIu16
" claims CNAME/DNAME at root. Refusing.", t
->id
);
2304 r
= dns_name_equal(dns_resource_key_name(dt
->key
), parent
);
2310 return t
->answer_authenticated
;
2320 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2322 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2324 if (dt
->key
->class != rr
->key
->class)
2326 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2329 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2335 /* We found the transaction that was supposed to find
2336 * the SOA RR for us. It was successful, but found no
2337 * RR for us. This means we are not at a zone cut. In
2338 * this case, we require authentication if the SOA
2339 * lookup was authenticated too. */
2340 return t
->answer_authenticated
;
2347 static int dns_transaction_in_private_tld(DnsTransaction
*t
, const DnsResourceKey
*key
) {
2353 /* If DNSSEC downgrade mode is on, checks whether the
2354 * specified RR is one level below a TLD we have proven not to
2355 * exist. In such a case we assume that this is a private
2356 * domain, and permit it.
2358 * This detects cases like the Fritz!Box router networks. Each
2359 * Fritz!Box router serves a private "fritz.box" zone, in the
2360 * non-existing TLD "box". Requests for the "fritz.box" domain
2361 * are served by the router itself, while requests for the
2362 * "box" domain will result in NXDOMAIN.
2364 * Note that this logic is unable to detect cases where a
2365 * router serves a private DNS zone directly under
2366 * non-existing TLD. In such a case we cannot detect whether
2367 * the TLD is supposed to exist or not, as all requests we
2368 * make for it will be answered by the router's zone, and not
2369 * by the root zone. */
2373 if (t
->scope
->dnssec_mode
!= DNSSEC_ALLOW_DOWNGRADE
)
2374 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2376 tld
= dns_resource_key_name(key
);
2377 r
= dns_name_parent(&tld
);
2381 return false; /* Already the root domain */
2383 if (!dns_name_is_single_label(tld
))
2386 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2388 if (dt
->key
->class != key
->class)
2391 r
= dns_name_equal(dns_resource_key_name(dt
->key
), tld
);
2397 /* We found an auxiliary lookup we did for the TLD. If
2398 * that returned with NXDOMAIN, we know the TLD didn't
2399 * exist, and hence this might be a private zone. */
2401 return dt
->answer_rcode
== DNS_RCODE_NXDOMAIN
;
2407 static int dns_transaction_requires_nsec(DnsTransaction
*t
) {
2408 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2417 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2418 * this negative reply */
2420 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2423 if (dns_type_is_pseudo(t
->key
->type
))
2426 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
2432 r
= dns_transaction_in_private_tld(t
, t
->key
);
2436 /* The lookup is from a TLD that is proven not to
2437 * exist, and we are in downgrade mode, hence ignore
2438 * that fact that we didn't get any NSEC RRs.*/
2440 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2441 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2445 name
= dns_resource_key_name(t
->key
);
2447 if (t
->key
->type
== DNS_TYPE_DS
) {
2449 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2450 * hence check the parent SOA in this case. */
2452 r
= dns_name_parent(&name
);
2458 type
= DNS_TYPE_SOA
;
2460 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
))
2461 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2464 /* For all other negative replies, check for the SOA lookup */
2465 type
= DNS_TYPE_SOA
;
2467 /* For all other RRs we check the SOA on the same level to see
2468 * if it's signed. */
2470 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2472 if (dt
->key
->class != t
->key
->class)
2474 if (dt
->key
->type
!= type
)
2477 r
= dns_name_equal(dns_resource_key_name(dt
->key
), name
);
2483 return dt
->answer_authenticated
;
2486 /* If in doubt, require NSEC/NSEC3 */
2490 static int dns_transaction_dnskey_authenticated(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2491 DnsResourceRecord
*rrsig
;
2495 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2496 * the specified RRset is authenticated (i.e. has a matching
2499 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2505 DNS_ANSWER_FOREACH(rrsig
, t
->answer
) {
2509 r
= dnssec_key_match_rrsig(rr
->key
, rrsig
);
2515 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2517 if (dt
->key
->class != rr
->key
->class)
2520 if (dt
->key
->type
== DNS_TYPE_DNSKEY
) {
2522 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2528 /* OK, we found an auxiliary DNSKEY
2529 * lookup. If that lookup is
2530 * authenticated, report this. */
2532 if (dt
->answer_authenticated
)
2537 } else if (dt
->key
->type
== DNS_TYPE_DS
) {
2539 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2545 /* OK, we found an auxiliary DS
2546 * lookup. If that lookup is
2547 * authenticated and non-zero, we
2550 if (!dt
->answer_authenticated
)
2553 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2558 return found
? false : -ENXIO
;
2561 static int dns_transaction_known_signed(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2565 /* We know that the root domain is signed, hence if it appears
2566 * not to be signed, there's a problem with the DNS server */
2568 return rr
->key
->class == DNS_CLASS_IN
&&
2569 dns_name_is_root(dns_resource_key_name(rr
->key
));
2572 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction
*t
) {
2573 DnsResourceRecord
*rr
;
2578 /* Maybe warn the user that we encountered a revoked DNSKEY
2579 * for a key from our trust anchor. Note that we don't care
2580 * whether the DNSKEY can be authenticated or not. It's
2581 * sufficient if it is self-signed. */
2583 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2584 r
= dns_trust_anchor_check_revoked(&t
->scope
->manager
->trust_anchor
, rr
, t
->answer
);
2592 static int dns_transaction_invalidate_revoked_keys(DnsTransaction
*t
) {
2598 /* Removes all DNSKEY/DS objects from t->validated_keys that
2599 * our trust anchors database considers revoked. */
2602 DnsResourceRecord
*rr
;
2606 DNS_ANSWER_FOREACH(rr
, t
->validated_keys
) {
2607 r
= dns_trust_anchor_is_revoked(&t
->scope
->manager
->trust_anchor
, rr
);
2611 r
= dns_answer_remove_by_rr(&t
->validated_keys
, rr
);
2625 static int dns_transaction_copy_validated(DnsTransaction
*t
) {
2632 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
2634 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2636 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
2639 if (!dt
->answer_authenticated
)
2642 r
= dns_answer_extend(&t
->validated_keys
, dt
->answer
);
2651 DNSSEC_PHASE_DNSKEY
, /* Phase #1, only validate DNSKEYs */
2652 DNSSEC_PHASE_NSEC
, /* Phase #2, only validate NSEC+NSEC3 */
2653 DNSSEC_PHASE_ALL
, /* Phase #3, validate everything else */
2656 static int dnssec_validate_records(
2660 DnsAnswer
**validated
) {
2662 DnsResourceRecord
*rr
;
2665 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
2667 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2668 DnsResourceRecord
*rrsig
= NULL
;
2669 DnssecResult result
;
2671 switch (rr
->key
->type
) {
2672 case DNS_TYPE_RRSIG
:
2675 case DNS_TYPE_DNSKEY
:
2676 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
2677 if (phase
== DNSSEC_PHASE_NSEC
)
2682 case DNS_TYPE_NSEC3
:
2685 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
2686 if (phase
== DNSSEC_PHASE_DNSKEY
)
2691 /* We validate all other RRs only in the ALL phases */
2692 if (phase
!= DNSSEC_PHASE_ALL
)
2696 r
= dnssec_verify_rrset_search(t
->answer
, rr
->key
, t
->validated_keys
, USEC_INFINITY
, &result
, &rrsig
);
2700 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr
)), dnssec_result_to_string(result
));
2702 if (result
== DNSSEC_VALIDATED
) {
2704 if (rr
->key
->type
== DNS_TYPE_DNSKEY
) {
2705 /* If we just validated a DNSKEY RRset, then let's add these keys to
2706 * the set of validated keys for this transaction. */
2708 r
= dns_answer_copy_by_key(&t
->validated_keys
, t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
);
2712 /* Some of the DNSKEYs we just added might already have been revoked,
2713 * remove them again in that case. */
2714 r
= dns_transaction_invalidate_revoked_keys(t
);
2719 /* Add the validated RRset to the new list of validated
2720 * RRsets, and remove it from the unvalidated RRsets.
2721 * We mark the RRset as authenticated and cacheable. */
2722 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
);
2726 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_SECURE
, rr
->key
);
2728 /* Exit the loop, we dropped something from the answer, start from the beginning */
2732 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
2733 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
2734 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
2735 if (phase
!= DNSSEC_PHASE_ALL
)
2738 if (result
== DNSSEC_VALIDATED_WILDCARD
) {
2739 bool authenticated
= false;
2742 /* This RRset validated, but as a wildcard. This means we need
2743 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists.*/
2745 /* First step, determine the source of synthesis */
2746 r
= dns_resource_record_source(rrsig
, &source
);
2750 r
= dnssec_test_positive_wildcard(*validated
,
2751 dns_resource_key_name(rr
->key
),
2753 rrsig
->rrsig
.signer
,
2756 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
2758 result
= DNSSEC_INVALID
;
2760 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
,
2761 authenticated
? (DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
) : 0);
2765 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, rr
->key
);
2767 /* Exit the loop, we dropped something from the answer, start from the beginning */
2772 if (result
== DNSSEC_NO_SIGNATURE
) {
2773 r
= dns_transaction_requires_rrsig(t
, rr
);
2777 /* Data does not require signing. In that case, just copy it over,
2778 * but remember that this is by no means authenticated.*/
2779 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2783 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2787 r
= dns_transaction_known_signed(t
, rr
);
2791 /* This is an RR we know has to be signed. If it isn't this means
2792 * the server is not attaching RRSIGs, hence complain. */
2794 dns_server_packet_rrsig_missing(t
->server
, t
->current_feature_level
);
2796 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
2798 /* Downgrading is OK? If so, just consider the information unsigned */
2800 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2804 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2808 /* Otherwise, fail */
2809 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2813 r
= dns_transaction_in_private_tld(t
, rr
->key
);
2817 char s
[DNS_RESOURCE_KEY_STRING_MAX
];
2819 /* The data is from a TLD that is proven not to exist, and we are in downgrade
2820 * mode, hence ignore the fact that this was not signed. */
2822 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
2823 dns_resource_key_to_string(rr
->key
, s
, sizeof s
));
2825 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2829 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2836 DNSSEC_SIGNATURE_EXPIRED
,
2837 DNSSEC_UNSUPPORTED_ALGORITHM
)) {
2839 r
= dns_transaction_dnskey_authenticated(t
, rr
);
2840 if (r
< 0 && r
!= -ENXIO
)
2843 /* The DNSKEY transaction was not authenticated, this means there's
2844 * no DS for this, which means it's OK if no keys are found for this signature. */
2846 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2850 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2855 r
= dns_transaction_is_primary_response(t
, rr
);
2859 /* Look for a matching DNAME for this CNAME */
2860 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2864 /* Also look among the stuff we already validated */
2865 r
= dns_answer_has_dname_for_cname(*validated
, rr
);
2873 DNSSEC_SIGNATURE_EXPIRED
,
2874 DNSSEC_NO_SIGNATURE
))
2875 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, rr
->key
);
2876 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
2877 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, rr
->key
);
2879 /* This is a primary response to our question, and it failed validation.
2881 t
->answer_dnssec_result
= result
;
2885 /* This is a primary response, but we do have a DNAME RR
2886 * in the RR that can replay this CNAME, hence rely on
2887 * that, and we can remove the CNAME in favour of it. */
2890 /* This is just some auxiliary data. Just remove the RRset and continue. */
2891 r
= dns_answer_remove_by_key(&t
->answer
, rr
->key
);
2895 /* We dropped something from the answer, start from the beginning. */
2899 return 2; /* Finito. */
2902 int dns_transaction_validate_dnssec(DnsTransaction
*t
) {
2903 _cleanup_(dns_answer_unrefp
) DnsAnswer
*validated
= NULL
;
2905 DnsAnswerFlags flags
;
2907 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2911 /* We have now collected all DS and DNSKEY RRs in
2912 * t->validated_keys, let's see which RRs we can now
2913 * authenticate with that. */
2915 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2918 /* Already validated */
2919 if (t
->answer_dnssec_result
!= _DNSSEC_RESULT_INVALID
)
2922 /* Our own stuff needs no validation */
2923 if (IN_SET(t
->answer_source
, DNS_TRANSACTION_ZONE
, DNS_TRANSACTION_TRUST_ANCHOR
)) {
2924 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2925 t
->answer_authenticated
= true;
2929 /* Cached stuff is not affected by validation. */
2930 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
2933 if (!dns_transaction_dnssec_supported_full(t
)) {
2934 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
2935 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2936 log_debug("Not validating response for %" PRIu16
", used server feature level does not support DNSSEC.", t
->id
);
2940 log_debug("Validating response from transaction %" PRIu16
" (%s).",
2942 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2944 /* First, see if this response contains any revoked trust
2945 * anchors we care about */
2946 r
= dns_transaction_check_revoked_trust_anchors(t
);
2950 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
2951 r
= dns_transaction_copy_validated(t
);
2955 /* Second, see if there are DNSKEYs we already know a
2956 * validated DS for. */
2957 r
= dns_transaction_validate_dnskey_by_ds(t
);
2961 /* Fourth, remove all DNSKEY and DS RRs again that our trust
2962 * anchor says are revoked. After all we might have marked
2963 * some keys revoked above, but they might still be lingering
2964 * in our validated_keys list. */
2965 r
= dns_transaction_invalidate_revoked_keys(t
);
2969 phase
= DNSSEC_PHASE_DNSKEY
;
2971 bool have_nsec
= false;
2973 r
= dnssec_validate_records(t
, phase
, &have_nsec
, &validated
);
2977 /* Try again as long as we managed to achieve something */
2981 if (phase
== DNSSEC_PHASE_DNSKEY
&& have_nsec
) {
2982 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
2983 phase
= DNSSEC_PHASE_NSEC
;
2987 if (phase
!= DNSSEC_PHASE_ALL
) {
2988 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
2989 * Note that in this third phase we start to remove RRs we couldn't validate. */
2990 phase
= DNSSEC_PHASE_ALL
;
2998 dns_answer_unref(t
->answer
);
2999 t
->answer
= validated
;
3002 /* At this point the answer only contains validated
3003 * RRsets. Now, let's see if it actually answers the question
3004 * we asked. If so, great! If it doesn't, then see if
3005 * NSEC/NSEC3 can prove this. */
3006 r
= dns_transaction_has_positive_answer(t
, &flags
);
3008 /* Yes, it answers the question! */
3010 if (flags
& DNS_ANSWER_AUTHENTICATED
) {
3011 /* The answer is fully authenticated, yay. */
3012 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3013 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3014 t
->answer_authenticated
= true;
3016 /* The answer is not fully authenticated. */
3017 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3018 t
->answer_authenticated
= false;
3021 } else if (r
== 0) {
3022 DnssecNsecResult nr
;
3023 bool authenticated
= false;
3025 /* Bummer! Let's check NSEC/NSEC3 */
3026 r
= dnssec_nsec_test(t
->answer
, t
->key
, &nr
, &authenticated
, &t
->answer_nsec_ttl
);
3032 case DNSSEC_NSEC_NXDOMAIN
:
3033 /* NSEC proves the domain doesn't exist. Very good. */
3034 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3035 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3036 t
->answer_rcode
= DNS_RCODE_NXDOMAIN
;
3037 t
->answer_authenticated
= authenticated
;
3039 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
3042 case DNSSEC_NSEC_NODATA
:
3043 /* NSEC proves that there's no data here, very good. */
3044 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3045 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3046 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3047 t
->answer_authenticated
= authenticated
;
3049 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
3052 case DNSSEC_NSEC_OPTOUT
:
3053 /* NSEC3 says the data might not be signed */
3054 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3055 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3056 t
->answer_authenticated
= false;
3058 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3061 case DNSSEC_NSEC_NO_RR
:
3062 /* No NSEC data? Bummer! */
3064 r
= dns_transaction_requires_nsec(t
);
3068 t
->answer_dnssec_result
= DNSSEC_NO_SIGNATURE
;
3069 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3071 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3072 t
->answer_authenticated
= false;
3073 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3078 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM
:
3079 /* We don't know the NSEC3 algorithm used? */
3080 t
->answer_dnssec_result
= DNSSEC_UNSUPPORTED_ALGORITHM
;
3081 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, t
->key
);
3084 case DNSSEC_NSEC_FOUND
:
3085 case DNSSEC_NSEC_CNAME
:
3086 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3087 t
->answer_dnssec_result
= DNSSEC_NSEC_MISMATCH
;
3088 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3092 assert_not_reached("Unexpected NSEC result.");
3099 static const char* const dns_transaction_state_table
[_DNS_TRANSACTION_STATE_MAX
] = {
3100 [DNS_TRANSACTION_NULL
] = "null",
3101 [DNS_TRANSACTION_PENDING
] = "pending",
3102 [DNS_TRANSACTION_VALIDATING
] = "validating",
3103 [DNS_TRANSACTION_RCODE_FAILURE
] = "rcode-failure",
3104 [DNS_TRANSACTION_SUCCESS
] = "success",
3105 [DNS_TRANSACTION_NO_SERVERS
] = "no-servers",
3106 [DNS_TRANSACTION_TIMEOUT
] = "timeout",
3107 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
] = "attempts-max-reached",
3108 [DNS_TRANSACTION_INVALID_REPLY
] = "invalid-reply",
3109 [DNS_TRANSACTION_ERRNO
] = "errno",
3110 [DNS_TRANSACTION_ABORTED
] = "aborted",
3111 [DNS_TRANSACTION_DNSSEC_FAILED
] = "dnssec-failed",
3112 [DNS_TRANSACTION_NO_TRUST_ANCHOR
] = "no-trust-anchor",
3113 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
] = "rr-type-unsupported",
3114 [DNS_TRANSACTION_NETWORK_DOWN
] = "network-down",
3115 [DNS_TRANSACTION_NOT_FOUND
] = "not-found",
3117 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state
, DnsTransactionState
);
3119 static const char* const dns_transaction_source_table
[_DNS_TRANSACTION_SOURCE_MAX
] = {
3120 [DNS_TRANSACTION_NETWORK
] = "network",
3121 [DNS_TRANSACTION_CACHE
] = "cache",
3122 [DNS_TRANSACTION_ZONE
] = "zone",
3123 [DNS_TRANSACTION_TRUST_ANCHOR
] = "trust-anchor",
3125 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source
, DnsTransactionSource
);