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 SET_FOREACH_MOVE(d
, t
->notify_transactions_done
, t
->notify_transactions
)
368 dns_transaction_notify(d
, t
);
369 SWAP_TWO(t
->notify_transactions
, t
->notify_transactions_done
);
372 dns_transaction_gc(t
);
375 static int dns_transaction_pick_server(DnsTransaction
*t
) {
379 assert(t
->scope
->protocol
== DNS_PROTOCOL_DNS
);
381 /* Pick a DNS server and a feature level for it. */
383 server
= dns_scope_get_dns_server(t
->scope
);
387 /* If we changed the server invalidate the feature level clamping, as the new server might have completely
388 * different properties. */
389 if (server
!= t
->server
)
390 t
->clamp_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
392 t
->current_feature_level
= dns_server_possible_feature_level(server
);
394 /* Clamp the feature level if that is requested. */
395 if (t
->clamp_feature_level
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
&&
396 t
->current_feature_level
> t
->clamp_feature_level
)
397 t
->current_feature_level
= t
->clamp_feature_level
;
399 log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t
->current_feature_level
), t
->id
);
401 if (server
== t
->server
)
404 dns_server_unref(t
->server
);
405 t
->server
= dns_server_ref(server
);
407 log_debug("Using DNS server %s for transaction %u.", dns_server_string(t
->server
), t
->id
);
412 static void dns_transaction_retry(DnsTransaction
*t
, bool next_server
) {
417 log_debug("Retrying transaction %" PRIu16
".", t
->id
);
419 /* Before we try again, switch to a new server. */
421 dns_scope_next_dns_server(t
->scope
);
423 r
= dns_transaction_go(t
);
425 t
->answer_errno
= -r
;
426 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
430 static int dns_transaction_maybe_restart(DnsTransaction
*t
) {
435 /* Returns > 0 if the transaction was restarted, 0 if not */
440 if (t
->current_feature_level
<= dns_server_possible_feature_level(t
->server
))
443 /* The server's current feature level is lower than when we sent the original query. We learnt something from
444 the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to
445 restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include
446 OPT RR or DO bit. One of these cases is documented here, for example:
447 https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
449 log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
450 dns_transaction_shuffle_id(t
);
452 r
= dns_transaction_go(t
);
459 static int on_stream_complete(DnsStream
*s
, int error
) {
460 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
464 assert(s
->transaction
);
466 /* Copy the data we care about out of the stream before we
469 p
= dns_packet_ref(s
->read_packet
);
471 dns_transaction_close_connection(t
);
473 if (ERRNO_IS_DISCONNECT(error
)) {
476 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
) {
477 /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the
478 * question on this scope. */
479 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
483 log_debug_errno(error
, "Connection failure for DNS TCP stream: %m");
484 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
485 dns_server_packet_lost(t
->server
, IPPROTO_TCP
, t
->current_feature_level
, usec
- t
->start_usec
);
487 dns_transaction_retry(t
, true);
491 t
->answer_errno
= error
;
492 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
496 if (dns_packet_validate_reply(p
) <= 0) {
497 log_debug("Invalid TCP reply packet.");
498 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
502 dns_scope_check_conflicts(t
->scope
, p
);
505 dns_transaction_process_reply(t
, p
);
508 /* If the response wasn't useful, then complete the transition
509 * now. After all, we are the worst feature set now with TCP
510 * sockets, and there's really no point in retrying. */
511 if (t
->state
== DNS_TRANSACTION_PENDING
)
512 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
514 dns_transaction_gc(t
);
519 static int dns_transaction_open_tcp(DnsTransaction
*t
) {
520 _cleanup_close_
int fd
= -1;
525 dns_transaction_close_connection(t
);
527 switch (t
->scope
->protocol
) {
529 case DNS_PROTOCOL_DNS
:
530 r
= dns_transaction_pick_server(t
);
534 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
537 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
541 fd
= dns_scope_socket_tcp(t
->scope
, AF_UNSPEC
, NULL
, t
->server
, 53);
544 case DNS_PROTOCOL_LLMNR
:
545 /* When we already received a reply to this (but it was truncated), send to its sender address */
547 fd
= dns_scope_socket_tcp(t
->scope
, t
->received
->family
, &t
->received
->sender
, NULL
, t
->received
->sender_port
);
549 union in_addr_union address
;
550 int family
= AF_UNSPEC
;
552 /* Otherwise, try to talk to the owner of a
553 * the IP address, in case this is a reverse
556 r
= dns_name_address(dns_resource_key_name(t
->key
), &family
, &address
);
561 if (family
!= t
->scope
->family
)
564 fd
= dns_scope_socket_tcp(t
->scope
, family
, &address
, NULL
, LLMNR_PORT
);
570 return -EAFNOSUPPORT
;
576 r
= dns_stream_new(t
->scope
->manager
, &t
->stream
, t
->scope
->protocol
, fd
);
581 r
= dns_stream_write_packet(t
->stream
, t
->sent
);
583 t
->stream
= dns_stream_unref(t
->stream
);
587 t
->stream
->complete
= on_stream_complete
;
588 t
->stream
->transaction
= t
;
590 /* The interface index is difficult to determine if we are
591 * connecting to the local host, hence fill this in right away
592 * instead of determining it from the socket */
593 t
->stream
->ifindex
= dns_scope_ifindex(t
->scope
);
595 dns_transaction_reset_answer(t
);
597 t
->tried_stream
= true;
602 static void dns_transaction_cache_answer(DnsTransaction
*t
) {
605 /* For mDNS we cache whenever we get the packet, rather than
606 * in each transaction. */
607 if (!IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
))
610 /* Caching disabled? */
611 if (!t
->scope
->manager
->enable_cache
)
614 /* We never cache if this packet is from the local host, under
615 * the assumption that a locally running DNS server would
616 * cache this anyway, and probably knows better when to flush
617 * the cache then we could. */
618 if (!DNS_PACKET_SHALL_CACHE(t
->received
))
621 dns_cache_put(&t
->scope
->cache
,
625 t
->answer_authenticated
,
629 &t
->received
->sender
);
632 static bool dns_transaction_dnssec_is_live(DnsTransaction
*t
) {
638 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
639 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
645 static int dns_transaction_dnssec_ready(DnsTransaction
*t
) {
651 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
652 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
654 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
658 case DNS_TRANSACTION_NULL
:
659 case DNS_TRANSACTION_PENDING
:
660 case DNS_TRANSACTION_VALIDATING
:
664 case DNS_TRANSACTION_RCODE_FAILURE
:
665 if (!IN_SET(dt
->answer_rcode
, DNS_RCODE_NXDOMAIN
, DNS_RCODE_SERVFAIL
)) {
666 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt
->answer_rcode
));
670 /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers
671 * erronously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS
672 * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar
673 * RRs to make unsigned proofs. */
675 case DNS_TRANSACTION_SUCCESS
:
679 case DNS_TRANSACTION_DNSSEC_FAILED
:
680 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
681 * validationr result */
683 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt
->answer_dnssec_result
));
684 t
->answer_dnssec_result
= dt
->answer_dnssec_result
; /* Copy error code over */
685 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
690 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt
->state
));
695 /* All is ready, we can go and validate */
699 t
->answer_dnssec_result
= DNSSEC_FAILED_AUXILIARY
;
700 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
704 static void dns_transaction_process_dnssec(DnsTransaction
*t
) {
709 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
710 r
= dns_transaction_dnssec_ready(t
);
713 if (r
== 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
716 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
717 * restart the lookup immediately. */
718 r
= dns_transaction_maybe_restart(t
);
721 if (r
> 0) /* Transaction got restarted... */
724 /* All our auxiliary DNSSEC transactions are complete now. Try
725 * to validate our RRset now. */
726 r
= dns_transaction_validate_dnssec(t
);
728 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
734 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
&&
735 t
->scope
->dnssec_mode
== DNSSEC_YES
) {
736 /* We are not in automatic downgrade mode, and the
737 * server is bad, refuse operation. */
738 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
742 if (!IN_SET(t
->answer_dnssec_result
,
743 _DNSSEC_RESULT_INVALID
, /* No DNSSEC validation enabled */
744 DNSSEC_VALIDATED
, /* Answer is signed and validated successfully */
745 DNSSEC_UNSIGNED
, /* Answer is right-fully unsigned */
746 DNSSEC_INCOMPATIBLE_SERVER
)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
747 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
751 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
)
752 dns_server_warn_downgrade(t
->server
);
754 dns_transaction_cache_answer(t
);
756 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
757 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
759 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
764 t
->answer_errno
= -r
;
765 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
768 static int dns_transaction_has_positive_answer(DnsTransaction
*t
, DnsAnswerFlags
*flags
) {
773 /* Checks whether the answer is positive, i.e. either a direct
774 * answer to the question, or a CNAME/DNAME for it */
776 r
= dns_answer_match_key(t
->answer
, t
->key
, flags
);
780 r
= dns_answer_find_cname_or_dname(t
->answer
, t
->key
, NULL
, flags
);
787 static int dns_transaction_fix_rcode(DnsTransaction
*t
) {
792 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
793 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
794 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
795 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
796 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
797 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
798 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
799 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
800 * incomplete CNAME/DNAME chain.
802 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
803 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
806 if (t
->answer_rcode
!= DNS_RCODE_NXDOMAIN
)
809 r
= dns_transaction_has_positive_answer(t
, NULL
);
813 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
817 void dns_transaction_process_reply(DnsTransaction
*t
, DnsPacket
*p
) {
824 assert(t
->scope
->manager
);
826 if (t
->state
!= DNS_TRANSACTION_PENDING
)
829 /* Note that this call might invalidate the query. Callers
830 * should hence not attempt to access the query or transaction
831 * after calling this function. */
833 log_debug("Processing incoming packet on transaction %" PRIu16
".", t
->id
);
835 switch (t
->scope
->protocol
) {
837 case DNS_PROTOCOL_LLMNR
:
838 /* For LLMNR we will not accept any packets from other interfaces */
840 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
843 if (p
->family
!= t
->scope
->family
)
846 /* Tentative packets are not full responses but still
847 * useful for identifying uniqueness conflicts during
849 if (DNS_PACKET_LLMNR_T(p
)) {
850 dns_transaction_tentative(t
, p
);
856 case DNS_PROTOCOL_MDNS
:
857 /* For mDNS we will not accept any packets from other interfaces */
859 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
862 if (p
->family
!= t
->scope
->family
)
867 case DNS_PROTOCOL_DNS
:
868 /* Note that we do not need to verify the
869 * addresses/port numbers of incoming traffic, as we
870 * invoked connect() on our UDP socket in which case
871 * the kernel already does the needed verification for
876 assert_not_reached("Invalid DNS protocol.");
879 if (t
->received
!= p
) {
880 dns_packet_unref(t
->received
);
881 t
->received
= dns_packet_ref(p
);
884 t
->answer_source
= DNS_TRANSACTION_NETWORK
;
886 if (p
->ipproto
== IPPROTO_TCP
) {
887 if (DNS_PACKET_TC(p
)) {
888 /* Truncated via TCP? Somebody must be fucking with us */
889 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
893 if (DNS_PACKET_ID(p
) != t
->id
) {
894 /* Not the reply to our query? Somebody must be fucking with us */
895 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
900 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
902 switch (t
->scope
->protocol
) {
904 case DNS_PROTOCOL_DNS
:
907 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_FORMERR
, DNS_RCODE_SERVFAIL
, DNS_RCODE_NOTIMP
)) {
909 /* Request failed, immediately try again with reduced features */
911 if (t
->current_feature_level
<= DNS_SERVER_FEATURE_LEVEL_WORST
) {
912 /* This was already at the lowest possible feature level? If so, we can't downgrade
913 * this transaction anymore, hence let's process the response, and accept the rcode. */
914 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
918 /* Reduce this feature level by one and try again. */
919 t
->clamp_feature_level
= t
->current_feature_level
- 1;
921 log_debug("Server returned error %s, retrying transaction with reduced feature level %s.",
922 dns_rcode_to_string(DNS_PACKET_RCODE(p
)),
923 dns_server_feature_level_to_string(t
->clamp_feature_level
));
925 dns_transaction_retry(t
, false /* use the same server */);
927 } else if (DNS_PACKET_TC(p
))
928 dns_server_packet_truncated(t
->server
, t
->current_feature_level
);
932 case DNS_PROTOCOL_LLMNR
:
933 case DNS_PROTOCOL_MDNS
:
934 dns_scope_packet_received(t
->scope
, ts
- t
->start_usec
);
938 assert_not_reached("Invalid DNS protocol.");
941 if (DNS_PACKET_TC(p
)) {
943 /* Truncated packets for mDNS are not allowed. Give up immediately. */
944 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
) {
945 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
949 log_debug("Reply truncated, retrying via TCP.");
951 /* Response was truncated, let's try again with good old TCP */
952 r
= dns_transaction_open_tcp(t
);
954 /* No servers found? Damn! */
955 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
958 if (r
== -EOPNOTSUPP
) {
959 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
960 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
964 /* On LLMNR, if we cannot connect to the host,
965 * we immediately give up */
966 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
969 /* On DNS, couldn't send? Try immediately again, with a new server */
970 dns_transaction_retry(t
, true);
976 /* After the superficial checks, actually parse the message. */
977 r
= dns_packet_extract(p
);
979 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
984 /* Report that we successfully received a valid packet with a good rcode after we initially got a bad
985 * rcode and subsequently downgraded the protocol */
987 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_SUCCESS
, DNS_RCODE_NXDOMAIN
) &&
988 t
->clamp_feature_level
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
)
989 dns_server_packet_rcode_downgrade(t
->server
, t
->clamp_feature_level
);
991 /* Report that the OPT RR was missing */
993 dns_server_packet_bad_opt(t
->server
, t
->current_feature_level
);
995 /* Report that we successfully received a packet */
996 dns_server_packet_received(t
->server
, p
->ipproto
, t
->current_feature_level
, ts
- t
->start_usec
, p
->size
);
999 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
1000 r
= dns_transaction_maybe_restart(t
);
1003 if (r
> 0) /* Transaction got restarted... */
1006 if (IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
, DNS_PROTOCOL_MDNS
)) {
1008 /* When dealing with protocols other than mDNS only consider responses with
1009 * equivalent query section to the request. For mDNS this check doesn't make
1010 * sense, because the section 6 of RFC6762 states that "Multicast DNS responses MUST NOT
1011 * contain any questions in the Question Section". */
1012 if (t
->scope
->protocol
!= DNS_PROTOCOL_MDNS
) {
1013 r
= dns_packet_is_reply_for(p
, t
->key
);
1017 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1022 /* Install the answer as answer to the transaction */
1023 dns_answer_unref(t
->answer
);
1024 t
->answer
= dns_answer_ref(p
->answer
);
1025 t
->answer_rcode
= DNS_PACKET_RCODE(p
);
1026 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
1027 t
->answer_authenticated
= false;
1029 r
= dns_transaction_fix_rcode(t
);
1033 /* Block GC while starting requests for additional DNSSEC RRs */
1035 r
= dns_transaction_request_dnssec_keys(t
);
1038 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
1039 if (!dns_transaction_gc(t
))
1042 /* Requesting additional keys might have resulted in
1043 * this transaction to fail, since the auxiliary
1044 * request failed for some reason. If so, we are not
1045 * in pending state anymore, and we should exit
1047 if (t
->state
!= DNS_TRANSACTION_PENDING
)
1052 /* There are DNSSEC transactions pending now. Update the state accordingly. */
1053 t
->state
= DNS_TRANSACTION_VALIDATING
;
1054 dns_transaction_close_connection(t
);
1055 dns_transaction_stop_timeout(t
);
1060 dns_transaction_process_dnssec(t
);
1064 t
->answer_errno
= -r
;
1065 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1068 static int on_dns_packet(sd_event_source
*s
, int fd
, uint32_t revents
, void *userdata
) {
1069 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1070 DnsTransaction
*t
= userdata
;
1076 r
= manager_recv(t
->scope
->manager
, fd
, DNS_PROTOCOL_DNS
, &p
);
1077 if (ERRNO_IS_DISCONNECT(-r
)) {
1080 /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next
1081 * recvmsg(). Treat this like a lost packet. */
1083 log_debug_errno(r
, "Connection failure for DNS UDP packet: %m");
1084 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
1085 dns_server_packet_lost(t
->server
, IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1087 dns_transaction_retry(t
, true);
1091 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1092 t
->answer_errno
= -r
;
1096 r
= dns_packet_validate_reply(p
);
1098 log_debug_errno(r
, "Received invalid DNS packet as response, ignoring: %m");
1102 log_debug("Received inappropriate DNS packet as response, ignoring.");
1106 if (DNS_PACKET_ID(p
) != t
->id
) {
1107 log_debug("Received packet with incorrect transaction ID, ignoring.");
1111 dns_transaction_process_reply(t
, p
);
1115 static int dns_transaction_emit_udp(DnsTransaction
*t
) {
1120 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1122 r
= dns_transaction_pick_server(t
);
1126 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_UDP
)
1129 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
1132 if (r
> 0 || t
->dns_udp_fd
< 0) { /* Server changed, or no connection yet. */
1135 dns_transaction_close_connection(t
);
1137 fd
= dns_scope_socket_udp(t
->scope
, t
->server
, 53);
1141 r
= sd_event_add_io(t
->scope
->manager
->event
, &t
->dns_udp_event_source
, fd
, EPOLLIN
, on_dns_packet
, t
);
1147 (void) sd_event_source_set_description(t
->dns_udp_event_source
, "dns-transaction-udp");
1151 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
1155 dns_transaction_close_connection(t
);
1157 r
= dns_scope_emit_udp(t
->scope
, t
->dns_udp_fd
, t
->sent
);
1161 dns_transaction_reset_answer(t
);
1166 static int on_transaction_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1167 DnsTransaction
*t
= userdata
;
1172 if (!t
->initial_jitter_scheduled
|| t
->initial_jitter_elapsed
) {
1173 /* Timeout reached? Increase the timeout for the server used */
1174 switch (t
->scope
->protocol
) {
1176 case DNS_PROTOCOL_DNS
:
1178 dns_server_packet_lost(t
->server
, t
->stream
? IPPROTO_TCP
: IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1181 case DNS_PROTOCOL_LLMNR
:
1182 case DNS_PROTOCOL_MDNS
:
1183 dns_scope_packet_lost(t
->scope
, usec
- t
->start_usec
);
1187 assert_not_reached("Invalid DNS protocol.");
1190 if (t
->initial_jitter_scheduled
)
1191 t
->initial_jitter_elapsed
= true;
1194 log_debug("Timeout reached on transaction %" PRIu16
".", t
->id
);
1196 dns_transaction_retry(t
, true);
1200 static usec_t
transaction_get_resend_timeout(DnsTransaction
*t
) {
1204 switch (t
->scope
->protocol
) {
1206 case DNS_PROTOCOL_DNS
:
1208 return t
->server
->resend_timeout
;
1210 case DNS_PROTOCOL_MDNS
:
1211 assert(t
->n_attempts
> 0);
1212 return (1 << (t
->n_attempts
- 1)) * USEC_PER_SEC
;
1214 case DNS_PROTOCOL_LLMNR
:
1215 return t
->scope
->resend_timeout
;
1218 assert_not_reached("Invalid DNS protocol.");
1222 static int dns_transaction_prepare(DnsTransaction
*t
, usec_t ts
) {
1227 dns_transaction_stop_timeout(t
);
1229 r
= dns_scope_network_good(t
->scope
);
1233 dns_transaction_complete(t
, DNS_TRANSACTION_NETWORK_DOWN
);
1237 if (t
->n_attempts
>= TRANSACTION_ATTEMPTS_MAX(t
->scope
->protocol
)) {
1238 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1242 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& t
->tried_stream
) {
1243 /* If we already tried via a stream, then we don't
1244 * retry on LLMNR. See RFC 4795, Section 2.7. */
1245 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1252 dns_transaction_reset_answer(t
);
1253 dns_transaction_flush_dnssec_transactions(t
);
1255 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1256 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1257 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, t
->key
, &t
->answer
);
1261 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1262 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1263 t
->answer_authenticated
= true;
1264 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1268 if (dns_name_is_root(dns_resource_key_name(t
->key
)) &&
1269 t
->key
->type
== DNS_TYPE_DS
) {
1271 /* Hmm, this is a request for the root DS? A
1272 * DS RR doesn't exist in the root zone, and
1273 * if our trust anchor didn't know it either,
1274 * this means we cannot do any DNSSEC logic
1277 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
1278 /* We are in downgrade mode. In this
1279 * case, synthesize an unsigned empty
1280 * response, so that the any lookup
1281 * depending on this one can continue
1282 * assuming there was no DS, and hence
1283 * the root zone was unsigned. */
1285 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1286 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1287 t
->answer_authenticated
= false;
1288 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1290 /* If we are not in downgrade mode,
1291 * then fail the lookup, because we
1292 * cannot reasonably answer it. There
1293 * might be DS RRs, but we don't know
1294 * them, and the DNS server won't tell
1295 * them to us (and even if it would,
1296 * we couldn't validate and trust them. */
1297 dns_transaction_complete(t
, DNS_TRANSACTION_NO_TRUST_ANCHOR
);
1303 /* Check the zone, but only if this transaction is not used
1304 * for probing or verifying a zone item. */
1305 if (set_isempty(t
->notify_zone_items
)) {
1307 r
= dns_zone_lookup(&t
->scope
->zone
, t
->key
, dns_scope_ifindex(t
->scope
), &t
->answer
, NULL
, NULL
);
1311 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1312 t
->answer_source
= DNS_TRANSACTION_ZONE
;
1313 t
->answer_authenticated
= true;
1314 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1319 /* Check the cache, but only if this transaction is not used
1320 * for probing or verifying a zone item. */
1321 if (set_isempty(t
->notify_zone_items
)) {
1323 /* Before trying the cache, let's make sure we figured out a
1324 * server to use. Should this cause a change of server this
1325 * might flush the cache. */
1326 dns_scope_get_dns_server(t
->scope
);
1328 /* Let's then prune all outdated entries */
1329 dns_cache_prune(&t
->scope
->cache
);
1331 r
= dns_cache_lookup(&t
->scope
->cache
, t
->key
, t
->clamp_ttl
, &t
->answer_rcode
, &t
->answer
, &t
->answer_authenticated
);
1335 t
->answer_source
= DNS_TRANSACTION_CACHE
;
1336 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
1337 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1339 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
1347 static int dns_transaction_make_packet_mdns(DnsTransaction
*t
) {
1349 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1350 bool add_known_answers
= false;
1351 DnsTransaction
*other
;
1357 assert(t
->scope
->protocol
== DNS_PROTOCOL_MDNS
);
1359 /* Discard any previously prepared packet, so we can start over and coalesce again */
1360 t
->sent
= dns_packet_unref(t
->sent
);
1362 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, false);
1366 r
= dns_packet_append_key(p
, t
->key
, NULL
);
1372 if (dns_key_is_shared(t
->key
))
1373 add_known_answers
= true;
1376 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1377 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1378 * in our current scope, and see whether their timing contraints allow them to be sent.
1381 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1383 LIST_FOREACH(transactions_by_scope
, other
, t
->scope
->transactions
) {
1385 /* Skip ourselves */
1389 if (other
->state
!= DNS_TRANSACTION_PENDING
)
1392 if (other
->next_attempt_after
> ts
)
1395 if (qdcount
>= UINT16_MAX
)
1398 r
= dns_packet_append_key(p
, other
->key
, NULL
);
1401 * If we can't stuff more questions into the packet, just give up.
1402 * One of the 'other' transactions will fire later and take care of the rest.
1410 r
= dns_transaction_prepare(other
, ts
);
1414 ts
+= transaction_get_resend_timeout(other
);
1416 r
= sd_event_add_time(
1417 other
->scope
->manager
->event
,
1418 &other
->timeout_event_source
,
1419 clock_boottime_or_monotonic(),
1421 on_transaction_timeout
, other
);
1425 (void) sd_event_source_set_description(other
->timeout_event_source
, "dns-transaction-timeout");
1427 other
->state
= DNS_TRANSACTION_PENDING
;
1428 other
->next_attempt_after
= ts
;
1432 if (dns_key_is_shared(other
->key
))
1433 add_known_answers
= true;
1436 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(qdcount
);
1438 /* Append known answer section if we're asking for any shared record */
1439 if (add_known_answers
) {
1440 r
= dns_cache_export_shared_to_packet(&t
->scope
->cache
, p
);
1451 static int dns_transaction_make_packet(DnsTransaction
*t
) {
1452 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1457 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)
1458 return dns_transaction_make_packet_mdns(t
);
1463 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, t
->scope
->dnssec_mode
!= DNSSEC_NO
);
1467 r
= dns_packet_append_key(p
, t
->key
, NULL
);
1471 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
1472 DNS_PACKET_HEADER(p
)->id
= t
->id
;
1480 int dns_transaction_go(DnsTransaction
*t
) {
1483 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1487 /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has finished
1490 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1492 r
= dns_transaction_prepare(t
, ts
);
1496 log_debug("Transaction %" PRIu16
" for <%s> scope %s on %s/%s.",
1498 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
1499 dns_protocol_to_string(t
->scope
->protocol
),
1500 t
->scope
->link
? t
->scope
->link
->name
: "*",
1501 af_to_name_short(t
->scope
->family
));
1503 if (!t
->initial_jitter_scheduled
&&
1504 (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
||
1505 t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)) {
1506 usec_t jitter
, accuracy
;
1508 /* RFC 4795 Section 2.7 suggests all queries should be
1509 * delayed by a random time from 0 to JITTER_INTERVAL. */
1511 t
->initial_jitter_scheduled
= true;
1513 random_bytes(&jitter
, sizeof(jitter
));
1515 switch (t
->scope
->protocol
) {
1517 case DNS_PROTOCOL_LLMNR
:
1518 jitter
%= LLMNR_JITTER_INTERVAL_USEC
;
1519 accuracy
= LLMNR_JITTER_INTERVAL_USEC
;
1522 case DNS_PROTOCOL_MDNS
:
1523 jitter
%= MDNS_JITTER_RANGE_USEC
;
1524 jitter
+= MDNS_JITTER_MIN_USEC
;
1525 accuracy
= MDNS_JITTER_RANGE_USEC
;
1528 assert_not_reached("bad protocol");
1531 r
= sd_event_add_time(
1532 t
->scope
->manager
->event
,
1533 &t
->timeout_event_source
,
1534 clock_boottime_or_monotonic(),
1535 ts
+ jitter
, accuracy
,
1536 on_transaction_timeout
, t
);
1540 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1543 t
->next_attempt_after
= ts
;
1544 t
->state
= DNS_TRANSACTION_PENDING
;
1546 log_debug("Delaying %s transaction for " USEC_FMT
"us.", dns_protocol_to_string(t
->scope
->protocol
), jitter
);
1550 /* Otherwise, we need to ask the network */
1551 r
= dns_transaction_make_packet(t
);
1555 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&&
1556 (dns_name_endswith(dns_resource_key_name(t
->key
), "in-addr.arpa") > 0 ||
1557 dns_name_endswith(dns_resource_key_name(t
->key
), "ip6.arpa") > 0)) {
1559 /* RFC 4795, Section 2.4. says reverse lookups shall
1560 * always be made via TCP on LLMNR */
1561 r
= dns_transaction_open_tcp(t
);
1563 /* Try via UDP, and if that fails due to large size or lack of
1564 * support try via TCP */
1565 r
= dns_transaction_emit_udp(t
);
1567 log_debug("Sending query via TCP since it is too large.");
1569 log_debug("Sending query via TCP since server doesn't support UDP.");
1570 if (r
== -EMSGSIZE
|| r
== -EAGAIN
)
1571 r
= dns_transaction_open_tcp(t
);
1575 /* No servers to send this to? */
1576 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
1579 if (r
== -EOPNOTSUPP
) {
1580 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1581 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
1584 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& ERRNO_IS_DISCONNECT(-r
)) {
1585 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
1586 * answer this request with this protocol. */
1587 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
1591 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1594 /* Couldn't send? Try immediately again, with a new server */
1595 dns_scope_next_dns_server(t
->scope
);
1597 return dns_transaction_go(t
);
1600 ts
+= transaction_get_resend_timeout(t
);
1602 r
= sd_event_add_time(
1603 t
->scope
->manager
->event
,
1604 &t
->timeout_event_source
,
1605 clock_boottime_or_monotonic(),
1607 on_transaction_timeout
, t
);
1611 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1613 t
->state
= DNS_TRANSACTION_PENDING
;
1614 t
->next_attempt_after
= ts
;
1619 static int dns_transaction_find_cyclic(DnsTransaction
*t
, DnsTransaction
*aux
) {
1627 /* Try to find cyclic dependencies between transaction objects */
1632 SET_FOREACH(n
, aux
->dnssec_transactions
, i
) {
1633 r
= dns_transaction_find_cyclic(t
, n
);
1641 static int dns_transaction_add_dnssec_transaction(DnsTransaction
*t
, DnsResourceKey
*key
, DnsTransaction
**ret
) {
1642 DnsTransaction
*aux
;
1649 aux
= dns_scope_find_transaction(t
->scope
, key
, true);
1651 r
= dns_transaction_new(&aux
, t
->scope
, key
);
1655 if (set_contains(t
->dnssec_transactions
, aux
)) {
1660 r
= dns_transaction_find_cyclic(t
, aux
);
1664 char s
[DNS_RESOURCE_KEY_STRING_MAX
], saux
[DNS_RESOURCE_KEY_STRING_MAX
];
1666 log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16
" (%s) as dependency for %" PRIu16
" (%s).",
1668 dns_resource_key_to_string(t
->key
, s
, sizeof s
),
1670 dns_resource_key_to_string(aux
->key
, saux
, sizeof saux
));
1676 r
= set_ensure_allocated(&t
->dnssec_transactions
, NULL
);
1680 r
= set_ensure_allocated(&aux
->notify_transactions
, NULL
);
1684 r
= set_ensure_allocated(&aux
->notify_transactions_done
, NULL
);
1688 r
= set_put(t
->dnssec_transactions
, aux
);
1692 r
= set_put(aux
->notify_transactions
, t
);
1694 (void) set_remove(t
->dnssec_transactions
, aux
);
1702 dns_transaction_gc(aux
);
1706 static int dns_transaction_request_dnssec_rr(DnsTransaction
*t
, DnsResourceKey
*key
) {
1707 _cleanup_(dns_answer_unrefp
) DnsAnswer
*a
= NULL
;
1708 DnsTransaction
*aux
;
1714 /* Try to get the data from the trust anchor */
1715 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, key
, &a
);
1719 r
= dns_answer_extend(&t
->validated_keys
, a
);
1726 /* This didn't work, ask for it via the network/cache then. */
1727 r
= dns_transaction_add_dnssec_transaction(t
, key
, &aux
);
1728 if (r
== -ELOOP
) /* This would result in a cyclic dependency */
1733 if (aux
->state
== DNS_TRANSACTION_NULL
) {
1734 r
= dns_transaction_go(aux
);
1742 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction
*t
, const char *name
) {
1747 /* Check whether the specified name is in the NTA
1748 * database, either in the global one, or the link-local
1751 r
= dns_trust_anchor_lookup_negative(&t
->scope
->manager
->trust_anchor
, name
);
1755 if (!t
->scope
->link
)
1758 return set_contains(t
->scope
->link
->dnssec_negative_trust_anchors
, name
);
1761 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction
*t
) {
1766 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
1767 * RRs to prove it */
1769 r
= dns_transaction_has_positive_answer(t
, NULL
);
1775 /* Is this key explicitly listed as a negative trust anchor?
1776 * If so, it's nothing we need to care about */
1777 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
1783 /* The answer does not contain any RRs that match to the
1784 * question. If so, let's see if there are any NSEC/NSEC3 RRs
1785 * included. If not, the answer is unsigned. */
1787 r
= dns_answer_contains_nsec_or_nsec3(t
->answer
);
1796 static int dns_transaction_is_primary_response(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
1802 /* Check if the specified RR is the "primary" response,
1803 * i.e. either matches the question precisely or is a
1804 * CNAME/DNAME for it. */
1806 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1810 return dns_resource_key_match_cname_or_dname(t
->key
, rr
->key
, NULL
);
1813 static bool dns_transaction_dnssec_supported(DnsTransaction
*t
) {
1816 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
1817 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
1819 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1822 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
1823 * be supported, hence return true. */
1827 /* Note that we do not check the feature level actually used for the transaction but instead the feature level
1828 * the server is known to support currently, as the transaction feature level might be lower than what the
1829 * server actually supports, since we might have downgraded this transaction's feature level because we got a
1830 * SERVFAIL earlier and wanted to check whether downgrading fixes it. */
1832 return dns_server_dnssec_supported(t
->server
);
1835 static bool dns_transaction_dnssec_supported_full(DnsTransaction
*t
) {
1841 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
1843 if (!dns_transaction_dnssec_supported(t
))
1846 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
1847 if (!dns_transaction_dnssec_supported(dt
))
1853 int dns_transaction_request_dnssec_keys(DnsTransaction
*t
) {
1854 DnsResourceRecord
*rr
;
1861 * Retrieve all auxiliary RRs for the answer we got, so that
1862 * we can verify signatures or prove that RRs are rightfully
1863 * unsigned. Specifically:
1865 * - For RRSIG we get the matching DNSKEY
1866 * - For DNSKEY we get the matching DS
1867 * - For unsigned SOA/NS we get the matching DS
1868 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
1869 * - For other unsigned RRs we get the matching SOA RR
1870 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
1871 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
1872 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
1875 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
1877 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
1878 return 0; /* We only need to validate stuff from the network */
1879 if (!dns_transaction_dnssec_supported(t
))
1880 return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */
1882 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
1884 if (dns_type_is_pseudo(rr
->key
->type
))
1887 /* If this RR is in the negative trust anchor, we don't need to validate it. */
1888 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
1894 switch (rr
->key
->type
) {
1896 case DNS_TYPE_RRSIG
: {
1897 /* For each RRSIG we request the matching DNSKEY */
1898 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*dnskey
= NULL
;
1900 /* If this RRSIG is about a DNSKEY RR and the
1901 * signer is the same as the owner, then we
1902 * already have the DNSKEY, and we don't have
1903 * to look for more. */
1904 if (rr
->rrsig
.type_covered
== DNS_TYPE_DNSKEY
) {
1905 r
= dns_name_equal(rr
->rrsig
.signer
, dns_resource_key_name(rr
->key
));
1912 /* If the signer is not a parent of our
1913 * original query, then this is about an
1914 * auxiliary RRset, but not anything we asked
1915 * for. In this case we aren't interested,
1916 * because we don't want to request additional
1917 * RRs for stuff we didn't really ask for, and
1918 * also to avoid request loops, where
1919 * additional RRs from one transaction result
1920 * in another transaction whose additonal RRs
1921 * point back to the original transaction, and
1923 r
= dns_name_endswith(dns_resource_key_name(t
->key
), rr
->rrsig
.signer
);
1929 dnskey
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DNSKEY
, rr
->rrsig
.signer
);
1933 log_debug("Requesting DNSKEY to validate transaction %" PRIu16
" (%s, RRSIG with key tag: %" PRIu16
").",
1934 t
->id
, dns_resource_key_name(rr
->key
), rr
->rrsig
.key_tag
);
1935 r
= dns_transaction_request_dnssec_rr(t
, dnskey
);
1941 case DNS_TYPE_DNSKEY
: {
1942 /* For each DNSKEY we request the matching DS */
1943 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1945 /* If the DNSKEY we are looking at is not for
1946 * zone we are interested in, nor any of its
1947 * parents, we aren't interested, and don't
1948 * request it. After all, we don't want to end
1949 * up in request loops, and want to keep
1950 * additional traffic down. */
1952 r
= dns_name_endswith(dns_resource_key_name(t
->key
), dns_resource_key_name(rr
->key
));
1958 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
1962 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, DNSKEY with key tag: %" PRIu16
").",
1963 t
->id
, dns_resource_key_name(rr
->key
), dnssec_keytag(rr
, false));
1964 r
= dns_transaction_request_dnssec_rr(t
, ds
);
1973 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1975 /* For an unsigned SOA or NS, try to acquire
1976 * the matching DS RR, as we are at a zone cut
1977 * then, and whether a DS exists tells us
1978 * whether the zone is signed. Do so only if
1979 * this RR matches our original question,
1982 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1988 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
1994 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
1998 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned SOA/NS RRset).",
1999 t
->id
, dns_resource_key_name(rr
->key
));
2000 r
= dns_transaction_request_dnssec_rr(t
, ds
);
2008 case DNS_TYPE_CNAME
:
2009 case DNS_TYPE_DNAME
: {
2010 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2013 /* CNAMEs and DNAMEs cannot be located at a
2014 * zone apex, hence ask for the parent SOA for
2015 * unsigned CNAME/DNAME RRs, maybe that's the
2016 * apex. But do all that only if this is
2017 * actually a response to our original
2020 * Similar for DS RRs, which are signed when
2021 * the parent SOA is signed. */
2023 r
= dns_transaction_is_primary_response(t
, rr
);
2029 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2035 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2041 name
= dns_resource_key_name(rr
->key
);
2042 r
= dns_name_parent(&name
);
2048 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, name
);
2052 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned CNAME/DNAME/DS RRset).",
2053 t
->id
, dns_resource_key_name(rr
->key
));
2054 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2062 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2064 /* For other unsigned RRsets (including
2065 * NSEC/NSEC3!), look for proof the zone is
2066 * unsigned, by requesting the SOA RR of the
2067 * zone. However, do so only if they are
2068 * directly relevant to our original
2071 r
= dns_transaction_is_primary_response(t
, rr
);
2077 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2083 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, dns_resource_key_name(rr
->key
));
2087 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned non-SOA/NS RRset <%s>).",
2088 t
->id
, dns_resource_key_name(rr
->key
), dns_resource_record_to_string(rr
));
2089 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2096 /* Above, we requested everything necessary to validate what
2097 * we got. Now, let's request what we need to validate what we
2100 r
= dns_transaction_has_unsigned_negative_answer(t
);
2107 name
= dns_resource_key_name(t
->key
);
2109 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2110 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2111 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2112 * though they have further children. If this was a DS request, then it's signed when the parent zone
2113 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2114 * to see if that is signed. */
2116 if (t
->key
->type
== DNS_TYPE_DS
) {
2117 r
= dns_name_parent(&name
);
2119 type
= DNS_TYPE_SOA
;
2120 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned empty DS response).",
2121 t
->id
, dns_resource_key_name(t
->key
));
2125 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
)) {
2128 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned empty SOA/NS response).",
2129 t
->id
, dns_resource_key_name(t
->key
));
2132 type
= DNS_TYPE_SOA
;
2133 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned empty non-SOA/NS/DS response).",
2134 t
->id
, dns_resource_key_name(t
->key
));
2138 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2140 soa
= dns_resource_key_new(t
->key
->class, type
, name
);
2144 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2150 return dns_transaction_dnssec_is_live(t
);
2153 void dns_transaction_notify(DnsTransaction
*t
, DnsTransaction
*source
) {
2157 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2158 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2159 the state is VALIDATING however, we should check if we are complete now. */
2161 if (t
->state
== DNS_TRANSACTION_VALIDATING
)
2162 dns_transaction_process_dnssec(t
);
2165 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction
*t
) {
2166 DnsResourceRecord
*rr
;
2171 /* Add all DNSKEY RRs from the answer that are validated by DS
2172 * RRs from the list of validated keys to the list of
2173 * validated keys. */
2175 DNS_ANSWER_FOREACH_IFINDEX(rr
, ifindex
, t
->answer
) {
2177 r
= dnssec_verify_dnskey_by_ds_search(rr
, t
->validated_keys
);
2183 /* If so, the DNSKEY is validated too. */
2184 r
= dns_answer_add_extend(&t
->validated_keys
, rr
, ifindex
, DNS_ANSWER_AUTHENTICATED
);
2192 static int dns_transaction_requires_rrsig(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2198 /* Checks if the RR we are looking for must be signed with an
2199 * RRSIG. This is used for positive responses. */
2201 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2204 if (dns_type_is_pseudo(rr
->key
->type
))
2207 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2213 switch (rr
->key
->type
) {
2215 case DNS_TYPE_RRSIG
:
2216 /* RRSIGs are the signatures themselves, they need no signing. */
2224 /* For SOA or NS RRs we look for a matching DS transaction */
2226 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2228 if (dt
->key
->class != rr
->key
->class)
2230 if (dt
->key
->type
!= DNS_TYPE_DS
)
2233 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2239 /* We found a DS transactions for the SOA/NS
2240 * RRs we are looking at. If it discovered signed DS
2241 * RRs, then we need to be signed, too. */
2243 if (!dt
->answer_authenticated
)
2246 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2249 /* We found nothing that proves this is safe to leave
2250 * this unauthenticated, hence ask inist on
2251 * authentication. */
2256 case DNS_TYPE_CNAME
:
2257 case DNS_TYPE_DNAME
: {
2258 const char *parent
= NULL
;
2263 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2265 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2268 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2270 if (dt
->key
->class != rr
->key
->class)
2272 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2276 parent
= dns_resource_key_name(rr
->key
);
2277 r
= dns_name_parent(&parent
);
2281 if (rr
->key
->type
== DNS_TYPE_DS
)
2284 /* A CNAME/DNAME without a parent? That's sooo weird. */
2285 log_debug("Transaction %" PRIu16
" claims CNAME/DNAME at root. Refusing.", t
->id
);
2290 r
= dns_name_equal(dns_resource_key_name(dt
->key
), parent
);
2296 return t
->answer_authenticated
;
2306 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2308 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2310 if (dt
->key
->class != rr
->key
->class)
2312 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2315 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2321 /* We found the transaction that was supposed to find
2322 * the SOA RR for us. It was successful, but found no
2323 * RR for us. This means we are not at a zone cut. In
2324 * this case, we require authentication if the SOA
2325 * lookup was authenticated too. */
2326 return t
->answer_authenticated
;
2333 static int dns_transaction_in_private_tld(DnsTransaction
*t
, const DnsResourceKey
*key
) {
2339 /* If DNSSEC downgrade mode is on, checks whether the
2340 * specified RR is one level below a TLD we have proven not to
2341 * exist. In such a case we assume that this is a private
2342 * domain, and permit it.
2344 * This detects cases like the Fritz!Box router networks. Each
2345 * Fritz!Box router serves a private "fritz.box" zone, in the
2346 * non-existing TLD "box". Requests for the "fritz.box" domain
2347 * are served by the router itself, while requests for the
2348 * "box" domain will result in NXDOMAIN.
2350 * Note that this logic is unable to detect cases where a
2351 * router serves a private DNS zone directly under
2352 * non-existing TLD. In such a case we cannot detect whether
2353 * the TLD is supposed to exist or not, as all requests we
2354 * make for it will be answered by the router's zone, and not
2355 * by the root zone. */
2359 if (t
->scope
->dnssec_mode
!= DNSSEC_ALLOW_DOWNGRADE
)
2360 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2362 tld
= dns_resource_key_name(key
);
2363 r
= dns_name_parent(&tld
);
2367 return false; /* Already the root domain */
2369 if (!dns_name_is_single_label(tld
))
2372 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2374 if (dt
->key
->class != key
->class)
2377 r
= dns_name_equal(dns_resource_key_name(dt
->key
), tld
);
2383 /* We found an auxiliary lookup we did for the TLD. If
2384 * that returned with NXDOMAIN, we know the TLD didn't
2385 * exist, and hence this might be a private zone. */
2387 return dt
->answer_rcode
== DNS_RCODE_NXDOMAIN
;
2393 static int dns_transaction_requires_nsec(DnsTransaction
*t
) {
2394 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2403 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2404 * this negative reply */
2406 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2409 if (dns_type_is_pseudo(t
->key
->type
))
2412 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
2418 r
= dns_transaction_in_private_tld(t
, t
->key
);
2422 /* The lookup is from a TLD that is proven not to
2423 * exist, and we are in downgrade mode, hence ignore
2424 * that fact that we didn't get any NSEC RRs.*/
2426 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2427 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2431 name
= dns_resource_key_name(t
->key
);
2433 if (t
->key
->type
== DNS_TYPE_DS
) {
2435 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2436 * hence check the parent SOA in this case. */
2438 r
= dns_name_parent(&name
);
2444 type
= DNS_TYPE_SOA
;
2446 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
))
2447 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2450 /* For all other negative replies, check for the SOA lookup */
2451 type
= DNS_TYPE_SOA
;
2453 /* For all other RRs we check the SOA on the same level to see
2454 * if it's signed. */
2456 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2458 if (dt
->key
->class != t
->key
->class)
2460 if (dt
->key
->type
!= type
)
2463 r
= dns_name_equal(dns_resource_key_name(dt
->key
), name
);
2469 return dt
->answer_authenticated
;
2472 /* If in doubt, require NSEC/NSEC3 */
2476 static int dns_transaction_dnskey_authenticated(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2477 DnsResourceRecord
*rrsig
;
2481 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2482 * the specified RRset is authenticated (i.e. has a matching
2485 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2491 DNS_ANSWER_FOREACH(rrsig
, t
->answer
) {
2495 r
= dnssec_key_match_rrsig(rr
->key
, rrsig
);
2501 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2503 if (dt
->key
->class != rr
->key
->class)
2506 if (dt
->key
->type
== DNS_TYPE_DNSKEY
) {
2508 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2514 /* OK, we found an auxiliary DNSKEY
2515 * lookup. If that lookup is
2516 * authenticated, report this. */
2518 if (dt
->answer_authenticated
)
2523 } else if (dt
->key
->type
== DNS_TYPE_DS
) {
2525 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2531 /* OK, we found an auxiliary DS
2532 * lookup. If that lookup is
2533 * authenticated and non-zero, we
2536 if (!dt
->answer_authenticated
)
2539 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2544 return found
? false : -ENXIO
;
2547 static int dns_transaction_known_signed(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2551 /* We know that the root domain is signed, hence if it appears
2552 * not to be signed, there's a problem with the DNS server */
2554 return rr
->key
->class == DNS_CLASS_IN
&&
2555 dns_name_is_root(dns_resource_key_name(rr
->key
));
2558 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction
*t
) {
2559 DnsResourceRecord
*rr
;
2564 /* Maybe warn the user that we encountered a revoked DNSKEY
2565 * for a key from our trust anchor. Note that we don't care
2566 * whether the DNSKEY can be authenticated or not. It's
2567 * sufficient if it is self-signed. */
2569 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2570 r
= dns_trust_anchor_check_revoked(&t
->scope
->manager
->trust_anchor
, rr
, t
->answer
);
2578 static int dns_transaction_invalidate_revoked_keys(DnsTransaction
*t
) {
2584 /* Removes all DNSKEY/DS objects from t->validated_keys that
2585 * our trust anchors database considers revoked. */
2588 DnsResourceRecord
*rr
;
2592 DNS_ANSWER_FOREACH(rr
, t
->validated_keys
) {
2593 r
= dns_trust_anchor_is_revoked(&t
->scope
->manager
->trust_anchor
, rr
);
2597 r
= dns_answer_remove_by_rr(&t
->validated_keys
, rr
);
2611 static int dns_transaction_copy_validated(DnsTransaction
*t
) {
2618 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
2620 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2622 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
2625 if (!dt
->answer_authenticated
)
2628 r
= dns_answer_extend(&t
->validated_keys
, dt
->answer
);
2637 DNSSEC_PHASE_DNSKEY
, /* Phase #1, only validate DNSKEYs */
2638 DNSSEC_PHASE_NSEC
, /* Phase #2, only validate NSEC+NSEC3 */
2639 DNSSEC_PHASE_ALL
, /* Phase #3, validate everything else */
2642 static int dnssec_validate_records(
2646 DnsAnswer
**validated
) {
2648 DnsResourceRecord
*rr
;
2651 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
2653 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2654 DnsResourceRecord
*rrsig
= NULL
;
2655 DnssecResult result
;
2657 switch (rr
->key
->type
) {
2658 case DNS_TYPE_RRSIG
:
2661 case DNS_TYPE_DNSKEY
:
2662 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
2663 if (phase
== DNSSEC_PHASE_NSEC
)
2668 case DNS_TYPE_NSEC3
:
2671 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
2672 if (phase
== DNSSEC_PHASE_DNSKEY
)
2677 /* We validate all other RRs only in the ALL phases */
2678 if (phase
!= DNSSEC_PHASE_ALL
)
2682 r
= dnssec_verify_rrset_search(t
->answer
, rr
->key
, t
->validated_keys
, USEC_INFINITY
, &result
, &rrsig
);
2686 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr
)), dnssec_result_to_string(result
));
2688 if (result
== DNSSEC_VALIDATED
) {
2690 if (rr
->key
->type
== DNS_TYPE_DNSKEY
) {
2691 /* If we just validated a DNSKEY RRset, then let's add these keys to
2692 * the set of validated keys for this transaction. */
2694 r
= dns_answer_copy_by_key(&t
->validated_keys
, t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
);
2698 /* Some of the DNSKEYs we just added might already have been revoked,
2699 * remove them again in that case. */
2700 r
= dns_transaction_invalidate_revoked_keys(t
);
2705 /* Add the validated RRset to the new list of validated
2706 * RRsets, and remove it from the unvalidated RRsets.
2707 * We mark the RRset as authenticated and cacheable. */
2708 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
);
2712 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_SECURE
, rr
->key
);
2714 /* Exit the loop, we dropped something from the answer, start from the beginning */
2718 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
2719 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
2720 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
2721 if (phase
!= DNSSEC_PHASE_ALL
)
2724 if (result
== DNSSEC_VALIDATED_WILDCARD
) {
2725 bool authenticated
= false;
2728 /* This RRset validated, but as a wildcard. This means we need
2729 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists.*/
2731 /* First step, determine the source of synthesis */
2732 r
= dns_resource_record_source(rrsig
, &source
);
2736 r
= dnssec_test_positive_wildcard(*validated
,
2737 dns_resource_key_name(rr
->key
),
2739 rrsig
->rrsig
.signer
,
2742 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
2744 result
= DNSSEC_INVALID
;
2746 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
,
2747 authenticated
? (DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
) : 0);
2751 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, rr
->key
);
2753 /* Exit the loop, we dropped something from the answer, start from the beginning */
2758 if (result
== DNSSEC_NO_SIGNATURE
) {
2759 r
= dns_transaction_requires_rrsig(t
, rr
);
2763 /* Data does not require signing. In that case, just copy it over,
2764 * but remember that this is by no means authenticated.*/
2765 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2769 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2773 r
= dns_transaction_known_signed(t
, rr
);
2777 /* This is an RR we know has to be signed. If it isn't this means
2778 * the server is not attaching RRSIGs, hence complain. */
2780 dns_server_packet_rrsig_missing(t
->server
, t
->current_feature_level
);
2782 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
2784 /* Downgrading is OK? If so, just consider the information unsigned */
2786 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2790 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2794 /* Otherwise, fail */
2795 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2799 r
= dns_transaction_in_private_tld(t
, rr
->key
);
2803 char s
[DNS_RESOURCE_KEY_STRING_MAX
];
2805 /* The data is from a TLD that is proven not to exist, and we are in downgrade
2806 * mode, hence ignore the fact that this was not signed. */
2808 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
2809 dns_resource_key_to_string(rr
->key
, s
, sizeof s
));
2811 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2815 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2822 DNSSEC_SIGNATURE_EXPIRED
,
2823 DNSSEC_UNSUPPORTED_ALGORITHM
)) {
2825 r
= dns_transaction_dnskey_authenticated(t
, rr
);
2826 if (r
< 0 && r
!= -ENXIO
)
2829 /* The DNSKEY transaction was not authenticated, this means there's
2830 * no DS for this, which means it's OK if no keys are found for this signature. */
2832 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2836 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2841 r
= dns_transaction_is_primary_response(t
, rr
);
2845 /* Look for a matching DNAME for this CNAME */
2846 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2850 /* Also look among the stuff we already validated */
2851 r
= dns_answer_has_dname_for_cname(*validated
, rr
);
2859 DNSSEC_SIGNATURE_EXPIRED
,
2860 DNSSEC_NO_SIGNATURE
))
2861 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, rr
->key
);
2862 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
2863 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, rr
->key
);
2865 /* This is a primary response to our question, and it failed validation.
2867 t
->answer_dnssec_result
= result
;
2871 /* This is a primary response, but we do have a DNAME RR
2872 * in the RR that can replay this CNAME, hence rely on
2873 * that, and we can remove the CNAME in favour of it. */
2876 /* This is just some auxiliary data. Just remove the RRset and continue. */
2877 r
= dns_answer_remove_by_key(&t
->answer
, rr
->key
);
2881 /* We dropped something from the answer, start from the beginning. */
2885 return 2; /* Finito. */
2888 int dns_transaction_validate_dnssec(DnsTransaction
*t
) {
2889 _cleanup_(dns_answer_unrefp
) DnsAnswer
*validated
= NULL
;
2891 DnsAnswerFlags flags
;
2893 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2897 /* We have now collected all DS and DNSKEY RRs in
2898 * t->validated_keys, let's see which RRs we can now
2899 * authenticate with that. */
2901 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2904 /* Already validated */
2905 if (t
->answer_dnssec_result
!= _DNSSEC_RESULT_INVALID
)
2908 /* Our own stuff needs no validation */
2909 if (IN_SET(t
->answer_source
, DNS_TRANSACTION_ZONE
, DNS_TRANSACTION_TRUST_ANCHOR
)) {
2910 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2911 t
->answer_authenticated
= true;
2915 /* Cached stuff is not affected by validation. */
2916 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
2919 if (!dns_transaction_dnssec_supported_full(t
)) {
2920 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
2921 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2922 log_debug("Not validating response for %" PRIu16
", used server feature level does not support DNSSEC.", t
->id
);
2926 log_debug("Validating response from transaction %" PRIu16
" (%s).",
2928 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2930 /* First, see if this response contains any revoked trust
2931 * anchors we care about */
2932 r
= dns_transaction_check_revoked_trust_anchors(t
);
2936 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
2937 r
= dns_transaction_copy_validated(t
);
2941 /* Second, see if there are DNSKEYs we already know a
2942 * validated DS for. */
2943 r
= dns_transaction_validate_dnskey_by_ds(t
);
2947 /* Fourth, remove all DNSKEY and DS RRs again that our trust
2948 * anchor says are revoked. After all we might have marked
2949 * some keys revoked above, but they might still be lingering
2950 * in our validated_keys list. */
2951 r
= dns_transaction_invalidate_revoked_keys(t
);
2955 phase
= DNSSEC_PHASE_DNSKEY
;
2957 bool have_nsec
= false;
2959 r
= dnssec_validate_records(t
, phase
, &have_nsec
, &validated
);
2963 /* Try again as long as we managed to achieve something */
2967 if (phase
== DNSSEC_PHASE_DNSKEY
&& have_nsec
) {
2968 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
2969 phase
= DNSSEC_PHASE_NSEC
;
2973 if (phase
!= DNSSEC_PHASE_ALL
) {
2974 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
2975 * Note that in this third phase we start to remove RRs we couldn't validate. */
2976 phase
= DNSSEC_PHASE_ALL
;
2984 dns_answer_unref(t
->answer
);
2985 t
->answer
= validated
;
2988 /* At this point the answer only contains validated
2989 * RRsets. Now, let's see if it actually answers the question
2990 * we asked. If so, great! If it doesn't, then see if
2991 * NSEC/NSEC3 can prove this. */
2992 r
= dns_transaction_has_positive_answer(t
, &flags
);
2994 /* Yes, it answers the question! */
2996 if (flags
& DNS_ANSWER_AUTHENTICATED
) {
2997 /* The answer is fully authenticated, yay. */
2998 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2999 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3000 t
->answer_authenticated
= true;
3002 /* The answer is not fully authenticated. */
3003 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3004 t
->answer_authenticated
= false;
3007 } else if (r
== 0) {
3008 DnssecNsecResult nr
;
3009 bool authenticated
= false;
3011 /* Bummer! Let's check NSEC/NSEC3 */
3012 r
= dnssec_nsec_test(t
->answer
, t
->key
, &nr
, &authenticated
, &t
->answer_nsec_ttl
);
3018 case DNSSEC_NSEC_NXDOMAIN
:
3019 /* NSEC proves the domain doesn't exist. Very good. */
3020 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3021 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3022 t
->answer_rcode
= DNS_RCODE_NXDOMAIN
;
3023 t
->answer_authenticated
= authenticated
;
3025 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
3028 case DNSSEC_NSEC_NODATA
:
3029 /* NSEC proves that there's no data here, very good. */
3030 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3031 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3032 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3033 t
->answer_authenticated
= authenticated
;
3035 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
3038 case DNSSEC_NSEC_OPTOUT
:
3039 /* NSEC3 says the data might not be signed */
3040 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3041 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3042 t
->answer_authenticated
= false;
3044 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3047 case DNSSEC_NSEC_NO_RR
:
3048 /* No NSEC data? Bummer! */
3050 r
= dns_transaction_requires_nsec(t
);
3054 t
->answer_dnssec_result
= DNSSEC_NO_SIGNATURE
;
3055 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3057 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3058 t
->answer_authenticated
= false;
3059 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3064 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM
:
3065 /* We don't know the NSEC3 algorithm used? */
3066 t
->answer_dnssec_result
= DNSSEC_UNSUPPORTED_ALGORITHM
;
3067 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, t
->key
);
3070 case DNSSEC_NSEC_FOUND
:
3071 case DNSSEC_NSEC_CNAME
:
3072 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3073 t
->answer_dnssec_result
= DNSSEC_NSEC_MISMATCH
;
3074 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3078 assert_not_reached("Unexpected NSEC result.");
3085 static const char* const dns_transaction_state_table
[_DNS_TRANSACTION_STATE_MAX
] = {
3086 [DNS_TRANSACTION_NULL
] = "null",
3087 [DNS_TRANSACTION_PENDING
] = "pending",
3088 [DNS_TRANSACTION_VALIDATING
] = "validating",
3089 [DNS_TRANSACTION_RCODE_FAILURE
] = "rcode-failure",
3090 [DNS_TRANSACTION_SUCCESS
] = "success",
3091 [DNS_TRANSACTION_NO_SERVERS
] = "no-servers",
3092 [DNS_TRANSACTION_TIMEOUT
] = "timeout",
3093 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
] = "attempts-max-reached",
3094 [DNS_TRANSACTION_INVALID_REPLY
] = "invalid-reply",
3095 [DNS_TRANSACTION_ERRNO
] = "errno",
3096 [DNS_TRANSACTION_ABORTED
] = "aborted",
3097 [DNS_TRANSACTION_DNSSEC_FAILED
] = "dnssec-failed",
3098 [DNS_TRANSACTION_NO_TRUST_ANCHOR
] = "no-trust-anchor",
3099 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
] = "rr-type-unsupported",
3100 [DNS_TRANSACTION_NETWORK_DOWN
] = "network-down",
3101 [DNS_TRANSACTION_NOT_FOUND
] = "not-found",
3103 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state
, DnsTransactionState
);
3105 static const char* const dns_transaction_source_table
[_DNS_TRANSACTION_SOURCE_MAX
] = {
3106 [DNS_TRANSACTION_NETWORK
] = "network",
3107 [DNS_TRANSACTION_CACHE
] = "cache",
3108 [DNS_TRANSACTION_ZONE
] = "zone",
3109 [DNS_TRANSACTION_TRUST_ANCHOR
] = "trust-anchor",
3111 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source
, DnsTransactionSource
);