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
) {
63 t
->stream
= dns_stream_free(t
->stream
);
64 t
->dns_udp_event_source
= sd_event_source_unref(t
->dns_udp_event_source
);
65 t
->dns_udp_fd
= safe_close(t
->dns_udp_fd
);
68 static void dns_transaction_stop_timeout(DnsTransaction
*t
) {
71 t
->timeout_event_source
= sd_event_source_unref(t
->timeout_event_source
);
74 DnsTransaction
* dns_transaction_free(DnsTransaction
*t
) {
82 log_debug("Freeing transaction %" PRIu16
".", t
->id
);
84 dns_transaction_close_connection(t
);
85 dns_transaction_stop_timeout(t
);
87 dns_packet_unref(t
->sent
);
88 dns_transaction_reset_answer(t
);
90 dns_server_unref(t
->server
);
93 hashmap_remove_value(t
->scope
->transactions_by_key
, t
->key
, t
);
94 LIST_REMOVE(transactions_by_scope
, t
->scope
->transactions
, t
);
97 hashmap_remove(t
->scope
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
));
100 while ((c
= set_steal_first(t
->notify_query_candidates
)))
101 set_remove(c
->transactions
, t
);
102 set_free(t
->notify_query_candidates
);
104 while ((c
= set_steal_first(t
->notify_query_candidates_done
)))
105 set_remove(c
->transactions
, t
);
106 set_free(t
->notify_query_candidates_done
);
108 while ((i
= set_steal_first(t
->notify_zone_items
)))
109 i
->probe_transaction
= NULL
;
110 set_free(t
->notify_zone_items
);
112 while ((i
= set_steal_first(t
->notify_zone_items_done
)))
113 i
->probe_transaction
= NULL
;
114 set_free(t
->notify_zone_items_done
);
116 while ((z
= set_steal_first(t
->notify_transactions
)))
117 set_remove(z
->dnssec_transactions
, t
);
118 set_free(t
->notify_transactions
);
120 while ((z
= set_steal_first(t
->notify_transactions_done
)))
121 set_remove(z
->dnssec_transactions
, t
);
122 set_free(t
->notify_transactions_done
);
124 dns_transaction_flush_dnssec_transactions(t
);
125 set_free(t
->dnssec_transactions
);
127 dns_answer_unref(t
->validated_keys
);
128 dns_resource_key_unref(t
->key
);
134 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction
*, dns_transaction_free
);
136 bool dns_transaction_gc(DnsTransaction
*t
) {
142 if (set_isempty(t
->notify_query_candidates
) &&
143 set_isempty(t
->notify_query_candidates_done
) &&
144 set_isempty(t
->notify_zone_items
) &&
145 set_isempty(t
->notify_zone_items_done
) &&
146 set_isempty(t
->notify_transactions
) &&
147 set_isempty(t
->notify_transactions_done
)) {
148 dns_transaction_free(t
);
155 static uint16_t pick_new_id(Manager
*m
) {
158 /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the number of
159 * transactions, and it's much lower than the space of IDs. */
161 assert_cc(TRANSACTIONS_MAX
< 0xFFFF);
164 random_bytes(&new_id
, sizeof(new_id
));
165 while (new_id
== 0 ||
166 hashmap_get(m
->dns_transactions
, UINT_TO_PTR(new_id
)));
171 int dns_transaction_new(DnsTransaction
**ret
, DnsScope
*s
, DnsResourceKey
*key
) {
172 _cleanup_(dns_transaction_freep
) DnsTransaction
*t
= NULL
;
179 /* Don't allow looking up invalid or pseudo RRs */
180 if (!dns_type_is_valid_query(key
->type
))
182 if (dns_type_is_obsolete(key
->type
))
185 /* We only support the IN class */
186 if (key
->class != DNS_CLASS_IN
&& key
->class != DNS_CLASS_ANY
)
189 if (hashmap_size(s
->manager
->dns_transactions
) >= TRANSACTIONS_MAX
)
192 r
= hashmap_ensure_allocated(&s
->manager
->dns_transactions
, NULL
);
196 r
= hashmap_ensure_allocated(&s
->transactions_by_key
, &dns_resource_key_hash_ops
);
200 t
= new0(DnsTransaction
, 1);
205 t
->answer_source
= _DNS_TRANSACTION_SOURCE_INVALID
;
206 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
207 t
->answer_nsec_ttl
= (uint32_t) -1;
208 t
->key
= dns_resource_key_ref(key
);
209 t
->current_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
211 t
->id
= pick_new_id(s
->manager
);
213 r
= hashmap_put(s
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
), t
);
219 r
= hashmap_replace(s
->transactions_by_key
, t
->key
, t
);
221 hashmap_remove(s
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
));
225 LIST_PREPEND(transactions_by_scope
, s
->transactions
, t
);
228 s
->manager
->n_transactions_total
++;
238 static void dns_transaction_shuffle_id(DnsTransaction
*t
) {
242 /* Pick a new ID for this transaction. */
244 new_id
= pick_new_id(t
->scope
->manager
);
245 assert_se(hashmap_remove_and_put(t
->scope
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
), UINT_TO_PTR(new_id
), t
) >= 0);
247 log_debug("Transaction %" PRIu16
" is now %" PRIu16
".", t
->id
, new_id
);
250 /* Make sure we generate a new packet with the new ID */
251 t
->sent
= dns_packet_unref(t
->sent
);
254 static void dns_transaction_tentative(DnsTransaction
*t
, DnsPacket
*p
) {
255 _cleanup_free_
char *pretty
= NULL
;
256 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
262 if (manager_our_packet(t
->scope
->manager
, p
) != 0)
265 (void) in_addr_to_string(p
->family
, &p
->sender
, &pretty
);
267 log_debug("Transaction %" PRIu16
" for <%s> on scope %s on %s/%s got tentative packet from %s.",
269 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
270 dns_protocol_to_string(t
->scope
->protocol
),
271 t
->scope
->link
? t
->scope
->link
->name
: "*",
272 af_to_name_short(t
->scope
->family
),
275 /* RFC 4795, Section 4.1 says that the peer with the
276 * lexicographically smaller IP address loses */
277 if (memcmp(&p
->sender
, &p
->destination
, FAMILY_ADDRESS_SIZE(p
->family
)) >= 0) {
278 log_debug("Peer has lexicographically larger IP address and thus lost in the conflict.");
282 log_debug("We have the lexicographically larger IP address and thus lost in the conflict.");
286 while ((z
= set_first(t
->notify_zone_items
))) {
287 /* First, make sure the zone item drops the reference
289 dns_zone_item_probe_stop(z
);
291 /* Secondly, report this as conflict, so that we might
292 * look for a different hostname */
293 dns_zone_item_conflict(z
);
297 dns_transaction_gc(t
);
300 void dns_transaction_complete(DnsTransaction
*t
, DnsTransactionState state
) {
301 DnsQueryCandidate
*c
;
305 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
308 assert(!DNS_TRANSACTION_IS_LIVE(state
));
310 if (state
== DNS_TRANSACTION_DNSSEC_FAILED
) {
311 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
);
313 log_struct(LOG_NOTICE
,
314 LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_FAILURE
),
315 LOG_MESSAGE("DNSSEC validation failed for question %s: %s", key_str
, dnssec_result_to_string(t
->answer_dnssec_result
)),
316 "DNS_TRANSACTION=%" PRIu16
, t
->id
,
317 "DNS_QUESTION=%s", key_str
,
318 "DNSSEC_RESULT=%s", dnssec_result_to_string(t
->answer_dnssec_result
),
319 "DNS_SERVER=%s", dns_server_string(t
->server
),
320 "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t
->server
->possible_feature_level
),
324 /* Note that this call might invalidate the query. Callers
325 * should hence not attempt to access the query or transaction
326 * after calling this function. */
328 if (state
== DNS_TRANSACTION_ERRNO
)
329 st
= errno_to_name(t
->answer_errno
);
331 st
= dns_transaction_state_to_string(state
);
333 log_debug("Transaction %" PRIu16
" for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s).",
335 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
336 dns_protocol_to_string(t
->scope
->protocol
),
337 t
->scope
->link
? t
->scope
->link
->name
: "*",
338 af_to_name_short(t
->scope
->family
),
340 t
->answer_source
< 0 ? "none" : dns_transaction_source_to_string(t
->answer_source
),
341 t
->answer_authenticated
? "authenticated" : "unsigned");
345 dns_transaction_close_connection(t
);
346 dns_transaction_stop_timeout(t
);
348 /* Notify all queries that are interested, but make sure the
349 * transaction isn't freed while we are still looking at it */
352 SET_FOREACH_MOVE(c
, t
->notify_query_candidates_done
, t
->notify_query_candidates
)
353 dns_query_candidate_notify(c
);
354 SWAP_TWO(t
->notify_query_candidates
, t
->notify_query_candidates_done
);
356 SET_FOREACH_MOVE(z
, t
->notify_zone_items_done
, t
->notify_zone_items
)
357 dns_zone_item_notify(z
);
358 SWAP_TWO(t
->notify_zone_items
, t
->notify_zone_items_done
);
360 SET_FOREACH_MOVE(d
, t
->notify_transactions_done
, t
->notify_transactions
)
361 dns_transaction_notify(d
, t
);
362 SWAP_TWO(t
->notify_transactions
, t
->notify_transactions_done
);
365 dns_transaction_gc(t
);
368 static int dns_transaction_pick_server(DnsTransaction
*t
) {
372 assert(t
->scope
->protocol
== DNS_PROTOCOL_DNS
);
374 server
= dns_scope_get_dns_server(t
->scope
);
378 t
->current_feature_level
= dns_server_possible_feature_level(server
);
380 if (server
== t
->server
)
383 dns_server_unref(t
->server
);
384 t
->server
= dns_server_ref(server
);
389 static void dns_transaction_retry(DnsTransaction
*t
) {
394 log_debug("Retrying transaction %" PRIu16
".", t
->id
);
396 /* Before we try again, switch to a new server. */
397 dns_scope_next_dns_server(t
->scope
);
399 r
= dns_transaction_go(t
);
401 t
->answer_errno
= -r
;
402 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
406 static int dns_transaction_maybe_restart(DnsTransaction
*t
) {
412 if (t
->current_feature_level
<= dns_server_possible_feature_level(t
->server
))
415 /* The server's current feature level is lower than when we sent the original query. We learnt something from
416 the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to
417 restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include
418 OPT RR or DO bit. One of these cases is documented here, for example:
419 https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
421 log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
422 dns_transaction_shuffle_id(t
);
423 return dns_transaction_go(t
);
426 static int on_stream_complete(DnsStream
*s
, int error
) {
427 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
431 assert(s
->transaction
);
433 /* Copy the data we care about out of the stream before we
436 p
= dns_packet_ref(s
->read_packet
);
438 t
->stream
= dns_stream_free(t
->stream
);
440 if (ERRNO_IS_DISCONNECT(error
)) {
443 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
) {
444 /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the
445 * question on this scope. */
446 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
450 log_debug_errno(error
, "Connection failure for DNS TCP stream: %m");
451 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
452 dns_server_packet_lost(t
->server
, IPPROTO_TCP
, t
->current_feature_level
, usec
- t
->start_usec
);
454 dns_transaction_retry(t
);
458 t
->answer_errno
= error
;
459 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
463 if (dns_packet_validate_reply(p
) <= 0) {
464 log_debug("Invalid TCP reply packet.");
465 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
469 dns_scope_check_conflicts(t
->scope
, p
);
472 dns_transaction_process_reply(t
, p
);
475 /* If the response wasn't useful, then complete the transition
476 * now. After all, we are the worst feature set now with TCP
477 * sockets, and there's really no point in retrying. */
478 if (t
->state
== DNS_TRANSACTION_PENDING
)
479 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
481 dns_transaction_gc(t
);
486 static int dns_transaction_open_tcp(DnsTransaction
*t
) {
487 _cleanup_close_
int fd
= -1;
492 dns_transaction_close_connection(t
);
494 switch (t
->scope
->protocol
) {
496 case DNS_PROTOCOL_DNS
:
497 r
= dns_transaction_pick_server(t
);
501 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
504 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
508 fd
= dns_scope_socket_tcp(t
->scope
, AF_UNSPEC
, NULL
, t
->server
, 53);
511 case DNS_PROTOCOL_LLMNR
:
512 /* When we already received a reply to this (but it was truncated), send to its sender address */
514 fd
= dns_scope_socket_tcp(t
->scope
, t
->received
->family
, &t
->received
->sender
, NULL
, t
->received
->sender_port
);
516 union in_addr_union address
;
517 int family
= AF_UNSPEC
;
519 /* Otherwise, try to talk to the owner of a
520 * the IP address, in case this is a reverse
523 r
= dns_name_address(dns_resource_key_name(t
->key
), &family
, &address
);
528 if (family
!= t
->scope
->family
)
531 fd
= dns_scope_socket_tcp(t
->scope
, family
, &address
, NULL
, LLMNR_PORT
);
537 return -EAFNOSUPPORT
;
543 r
= dns_stream_new(t
->scope
->manager
, &t
->stream
, t
->scope
->protocol
, fd
);
548 r
= dns_stream_write_packet(t
->stream
, t
->sent
);
550 t
->stream
= dns_stream_free(t
->stream
);
554 t
->stream
->complete
= on_stream_complete
;
555 t
->stream
->transaction
= t
;
557 /* The interface index is difficult to determine if we are
558 * connecting to the local host, hence fill this in right away
559 * instead of determining it from the socket */
560 t
->stream
->ifindex
= dns_scope_ifindex(t
->scope
);
562 dns_transaction_reset_answer(t
);
564 t
->tried_stream
= true;
569 static void dns_transaction_cache_answer(DnsTransaction
*t
) {
572 /* For mDNS we cache whenever we get the packet, rather than
573 * in each transaction. */
574 if (!IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
))
577 /* We never cache if this packet is from the local host, under
578 * the assumption that a locally running DNS server would
579 * cache this anyway, and probably knows better when to flush
580 * the cache then we could. */
581 if (!DNS_PACKET_SHALL_CACHE(t
->received
))
584 dns_cache_put(&t
->scope
->cache
,
588 t
->answer_authenticated
,
592 &t
->received
->sender
);
595 static bool dns_transaction_dnssec_is_live(DnsTransaction
*t
) {
601 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
602 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
608 static int dns_transaction_dnssec_ready(DnsTransaction
*t
) {
614 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
615 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
617 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
621 case DNS_TRANSACTION_NULL
:
622 case DNS_TRANSACTION_PENDING
:
623 case DNS_TRANSACTION_VALIDATING
:
627 case DNS_TRANSACTION_RCODE_FAILURE
:
628 if (dt
->answer_rcode
!= DNS_RCODE_NXDOMAIN
) {
629 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt
->answer_rcode
));
633 /* Fall-through: NXDOMAIN is good enough for us. This is because some DNS servers erronously
634 * return NXDOMAIN for empty non-terminals (Akamai...), and we need to handle that nicely, when
635 * asking for parent SOA or similar RRs to make unsigned proofs. */
637 case DNS_TRANSACTION_SUCCESS
:
641 case DNS_TRANSACTION_DNSSEC_FAILED
:
642 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
643 * validationr result */
645 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt
->answer_dnssec_result
));
646 t
->answer_dnssec_result
= dt
->answer_dnssec_result
; /* Copy error code over */
647 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
652 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt
->state
));
657 /* All is ready, we can go and validate */
661 t
->answer_dnssec_result
= DNSSEC_FAILED_AUXILIARY
;
662 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
666 static void dns_transaction_process_dnssec(DnsTransaction
*t
) {
671 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
672 r
= dns_transaction_dnssec_ready(t
);
675 if (r
== 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
678 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
679 * restart the lookup immediately. */
680 r
= dns_transaction_maybe_restart(t
);
683 if (r
> 0) /* Transaction got restarted... */
686 /* All our auxiliary DNSSEC transactions are complete now. Try
687 * to validate our RRset now. */
688 r
= dns_transaction_validate_dnssec(t
);
690 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
696 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
&&
697 t
->scope
->dnssec_mode
== DNSSEC_YES
) {
698 /* We are not in automatic downgrade mode, and the
699 * server is bad, refuse operation. */
700 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
704 if (!IN_SET(t
->answer_dnssec_result
,
705 _DNSSEC_RESULT_INVALID
, /* No DNSSEC validation enabled */
706 DNSSEC_VALIDATED
, /* Answer is signed and validated successfully */
707 DNSSEC_UNSIGNED
, /* Answer is right-fully unsigned */
708 DNSSEC_INCOMPATIBLE_SERVER
)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
709 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
713 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
)
714 dns_server_warn_downgrade(t
->server
);
716 dns_transaction_cache_answer(t
);
718 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
719 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
721 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
726 t
->answer_errno
= -r
;
727 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
730 static int dns_transaction_has_positive_answer(DnsTransaction
*t
, DnsAnswerFlags
*flags
) {
735 /* Checks whether the answer is positive, i.e. either a direct
736 * answer to the question, or a CNAME/DNAME for it */
738 r
= dns_answer_match_key(t
->answer
, t
->key
, flags
);
742 r
= dns_answer_find_cname_or_dname(t
->answer
, t
->key
, NULL
, flags
);
749 static int dns_transaction_fix_rcode(DnsTransaction
*t
) {
754 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
755 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
756 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
757 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
758 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
759 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
760 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
761 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
762 * incomplete CNAME/DNAME chain.
764 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
765 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
768 if (t
->answer_rcode
!= DNS_RCODE_NXDOMAIN
)
771 r
= dns_transaction_has_positive_answer(t
, NULL
);
775 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
779 void dns_transaction_process_reply(DnsTransaction
*t
, DnsPacket
*p
) {
786 assert(t
->scope
->manager
);
788 if (t
->state
!= DNS_TRANSACTION_PENDING
)
791 /* Note that this call might invalidate the query. Callers
792 * should hence not attempt to access the query or transaction
793 * after calling this function. */
795 log_debug("Processing incoming packet on transaction %" PRIu16
".", t
->id
);
797 switch (t
->scope
->protocol
) {
799 case DNS_PROTOCOL_LLMNR
:
800 /* For LLMNR we will not accept any packets from other interfaces */
802 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
805 if (p
->family
!= t
->scope
->family
)
808 /* Tentative packets are not full responses but still
809 * useful for identifying uniqueness conflicts during
811 if (DNS_PACKET_LLMNR_T(p
)) {
812 dns_transaction_tentative(t
, p
);
818 case DNS_PROTOCOL_MDNS
:
819 /* For mDNS we will not accept any packets from other interfaces */
821 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
824 if (p
->family
!= t
->scope
->family
)
829 case DNS_PROTOCOL_DNS
:
830 /* Note that we do not need to verify the
831 * addresses/port numbers of incoming traffic, as we
832 * invoked connect() on our UDP socket in which case
833 * the kernel already does the needed verification for
838 assert_not_reached("Invalid DNS protocol.");
841 if (t
->received
!= p
) {
842 dns_packet_unref(t
->received
);
843 t
->received
= dns_packet_ref(p
);
846 t
->answer_source
= DNS_TRANSACTION_NETWORK
;
848 if (p
->ipproto
== IPPROTO_TCP
) {
849 if (DNS_PACKET_TC(p
)) {
850 /* Truncated via TCP? Somebody must be fucking with us */
851 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
855 if (DNS_PACKET_ID(p
) != t
->id
) {
856 /* Not the reply to our query? Somebody must be fucking with us */
857 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
862 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
864 switch (t
->scope
->protocol
) {
866 case DNS_PROTOCOL_DNS
:
869 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_FORMERR
, DNS_RCODE_SERVFAIL
, DNS_RCODE_NOTIMP
)) {
871 /* Request failed, immediately try again with reduced features */
872 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
874 dns_server_packet_failed(t
->server
, t
->current_feature_level
);
875 dns_transaction_retry(t
);
877 } else if (DNS_PACKET_TC(p
))
878 dns_server_packet_truncated(t
->server
, t
->current_feature_level
);
882 case DNS_PROTOCOL_LLMNR
:
883 case DNS_PROTOCOL_MDNS
:
884 dns_scope_packet_received(t
->scope
, ts
- t
->start_usec
);
888 assert_not_reached("Invalid DNS protocol.");
891 if (DNS_PACKET_TC(p
)) {
893 /* Truncated packets for mDNS are not allowed. Give up immediately. */
894 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
) {
895 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
899 log_debug("Reply truncated, retrying via TCP.");
901 /* Response was truncated, let's try again with good old TCP */
902 r
= dns_transaction_open_tcp(t
);
904 /* No servers found? Damn! */
905 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
908 if (r
== -EOPNOTSUPP
) {
909 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
910 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
914 /* On LLMNR, if we cannot connect to the host,
915 * we immediately give up */
916 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
919 /* On DNS, couldn't send? Try immediately again, with a new server */
920 dns_transaction_retry(t
);
926 /* After the superficial checks, actually parse the message. */
927 r
= dns_packet_extract(p
);
929 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
933 /* Report that the OPT RR was missing */
936 dns_server_packet_bad_opt(t
->server
, t
->current_feature_level
);
938 dns_server_packet_received(t
->server
, p
->ipproto
, t
->current_feature_level
, ts
- t
->start_usec
, p
->size
);
941 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
942 r
= dns_transaction_maybe_restart(t
);
945 if (r
> 0) /* Transaction got restarted... */
948 if (IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
)) {
950 /* Only consider responses with equivalent query section to the request */
951 r
= dns_packet_is_reply_for(p
, t
->key
);
955 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
959 /* Install the answer as answer to the transaction */
960 dns_answer_unref(t
->answer
);
961 t
->answer
= dns_answer_ref(p
->answer
);
962 t
->answer_rcode
= DNS_PACKET_RCODE(p
);
963 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
964 t
->answer_authenticated
= false;
966 r
= dns_transaction_fix_rcode(t
);
970 /* Block GC while starting requests for additional DNSSEC RRs */
972 r
= dns_transaction_request_dnssec_keys(t
);
975 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
976 if (!dns_transaction_gc(t
))
979 /* Requesting additional keys might have resulted in
980 * this transaction to fail, since the auxiliary
981 * request failed for some reason. If so, we are not
982 * in pending state anymore, and we should exit
984 if (t
->state
!= DNS_TRANSACTION_PENDING
)
989 /* There are DNSSEC transactions pending now. Update the state accordingly. */
990 t
->state
= DNS_TRANSACTION_VALIDATING
;
991 dns_transaction_close_connection(t
);
992 dns_transaction_stop_timeout(t
);
997 dns_transaction_process_dnssec(t
);
1001 t
->answer_errno
= -r
;
1002 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1005 static int on_dns_packet(sd_event_source
*s
, int fd
, uint32_t revents
, void *userdata
) {
1006 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1007 DnsTransaction
*t
= userdata
;
1013 r
= manager_recv(t
->scope
->manager
, fd
, DNS_PROTOCOL_DNS
, &p
);
1014 if (ERRNO_IS_DISCONNECT(-r
)) {
1017 /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next
1018 * recvmsg(). Treat this like a lost packet. */
1020 log_debug_errno(r
, "Connection failure for DNS UDP packet: %m");
1021 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
1022 dns_server_packet_lost(t
->server
, IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1024 dns_transaction_retry(t
);
1028 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1029 t
->answer_errno
= -r
;
1033 r
= dns_packet_validate_reply(p
);
1035 log_debug_errno(r
, "Received invalid DNS packet as response, ignoring: %m");
1039 log_debug("Received inappropriate DNS packet as response, ignoring.");
1043 if (DNS_PACKET_ID(p
) != t
->id
) {
1044 log_debug("Received packet with incorrect transaction ID, ignoring.");
1048 dns_transaction_process_reply(t
, p
);
1052 static int dns_transaction_emit_udp(DnsTransaction
*t
) {
1057 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1059 r
= dns_transaction_pick_server(t
);
1063 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_UDP
)
1066 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
1069 if (r
> 0 || t
->dns_udp_fd
< 0) { /* Server changed, or no connection yet. */
1072 dns_transaction_close_connection(t
);
1074 fd
= dns_scope_socket_udp(t
->scope
, t
->server
, 53);
1078 r
= sd_event_add_io(t
->scope
->manager
->event
, &t
->dns_udp_event_source
, fd
, EPOLLIN
, on_dns_packet
, t
);
1084 (void) sd_event_source_set_description(t
->dns_udp_event_source
, "dns-transaction-udp");
1088 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
1092 dns_transaction_close_connection(t
);
1094 r
= dns_scope_emit_udp(t
->scope
, t
->dns_udp_fd
, t
->sent
);
1098 dns_transaction_reset_answer(t
);
1103 static int on_transaction_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1104 DnsTransaction
*t
= userdata
;
1109 if (!t
->initial_jitter_scheduled
|| t
->initial_jitter_elapsed
) {
1110 /* Timeout reached? Increase the timeout for the server used */
1111 switch (t
->scope
->protocol
) {
1113 case DNS_PROTOCOL_DNS
:
1115 dns_server_packet_lost(t
->server
, t
->stream
? IPPROTO_TCP
: IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1118 case DNS_PROTOCOL_LLMNR
:
1119 case DNS_PROTOCOL_MDNS
:
1120 dns_scope_packet_lost(t
->scope
, usec
- t
->start_usec
);
1124 assert_not_reached("Invalid DNS protocol.");
1127 if (t
->initial_jitter_scheduled
)
1128 t
->initial_jitter_elapsed
= true;
1131 log_debug("Timeout reached on transaction %" PRIu16
".", t
->id
);
1133 dns_transaction_retry(t
);
1137 static usec_t
transaction_get_resend_timeout(DnsTransaction
*t
) {
1141 switch (t
->scope
->protocol
) {
1143 case DNS_PROTOCOL_DNS
:
1145 return t
->server
->resend_timeout
;
1147 case DNS_PROTOCOL_MDNS
:
1148 assert(t
->n_attempts
> 0);
1149 return (1 << (t
->n_attempts
- 1)) * USEC_PER_SEC
;
1151 case DNS_PROTOCOL_LLMNR
:
1152 return t
->scope
->resend_timeout
;
1155 assert_not_reached("Invalid DNS protocol.");
1159 static int dns_transaction_prepare(DnsTransaction
*t
, usec_t ts
) {
1164 dns_transaction_stop_timeout(t
);
1166 r
= dns_scope_network_good(t
->scope
);
1170 dns_transaction_complete(t
, DNS_TRANSACTION_NETWORK_DOWN
);
1174 if (t
->n_attempts
>= TRANSACTION_ATTEMPTS_MAX(t
->scope
->protocol
)) {
1175 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1179 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& t
->tried_stream
) {
1180 /* If we already tried via a stream, then we don't
1181 * retry on LLMNR. See RFC 4795, Section 2.7. */
1182 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1189 dns_transaction_reset_answer(t
);
1190 dns_transaction_flush_dnssec_transactions(t
);
1192 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1193 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1194 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, t
->key
, &t
->answer
);
1198 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1199 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1200 t
->answer_authenticated
= true;
1201 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1205 if (dns_name_is_root(dns_resource_key_name(t
->key
)) &&
1206 t
->key
->type
== DNS_TYPE_DS
) {
1208 /* Hmm, this is a request for the root DS? A
1209 * DS RR doesn't exist in the root zone, and
1210 * if our trust anchor didn't know it either,
1211 * this means we cannot do any DNSSEC logic
1214 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
1215 /* We are in downgrade mode. In this
1216 * case, synthesize an unsigned empty
1217 * response, so that the any lookup
1218 * depending on this one can continue
1219 * assuming there was no DS, and hence
1220 * the root zone was unsigned. */
1222 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1223 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1224 t
->answer_authenticated
= false;
1225 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1227 /* If we are not in downgrade mode,
1228 * then fail the lookup, because we
1229 * cannot reasonably answer it. There
1230 * might be DS RRs, but we don't know
1231 * them, and the DNS server won't tell
1232 * them to us (and even if it would,
1233 * we couldn't validate and trust them. */
1234 dns_transaction_complete(t
, DNS_TRANSACTION_NO_TRUST_ANCHOR
);
1240 /* Check the zone, but only if this transaction is not used
1241 * for probing or verifying a zone item. */
1242 if (set_isempty(t
->notify_zone_items
)) {
1244 r
= dns_zone_lookup(&t
->scope
->zone
, t
->key
, dns_scope_ifindex(t
->scope
), &t
->answer
, NULL
, NULL
);
1248 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1249 t
->answer_source
= DNS_TRANSACTION_ZONE
;
1250 t
->answer_authenticated
= true;
1251 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1256 /* Check the cache, but only if this transaction is not used
1257 * for probing or verifying a zone item. */
1258 if (set_isempty(t
->notify_zone_items
)) {
1260 /* Before trying the cache, let's make sure we figured out a
1261 * server to use. Should this cause a change of server this
1262 * might flush the cache. */
1263 dns_scope_get_dns_server(t
->scope
);
1265 /* Let's then prune all outdated entries */
1266 dns_cache_prune(&t
->scope
->cache
);
1268 r
= dns_cache_lookup(&t
->scope
->cache
, t
->key
, &t
->answer_rcode
, &t
->answer
, &t
->answer_authenticated
);
1272 t
->answer_source
= DNS_TRANSACTION_CACHE
;
1273 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
1274 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1276 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
1284 static int dns_transaction_make_packet_mdns(DnsTransaction
*t
) {
1286 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1287 bool add_known_answers
= false;
1288 DnsTransaction
*other
;
1294 assert(t
->scope
->protocol
== DNS_PROTOCOL_MDNS
);
1296 /* Discard any previously prepared packet, so we can start over and coalesce again */
1297 t
->sent
= dns_packet_unref(t
->sent
);
1299 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, false);
1303 r
= dns_packet_append_key(p
, t
->key
, NULL
);
1309 if (dns_key_is_shared(t
->key
))
1310 add_known_answers
= true;
1313 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1314 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1315 * in our current scope, and see whether their timing contraints allow them to be sent.
1318 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1320 LIST_FOREACH(transactions_by_scope
, other
, t
->scope
->transactions
) {
1322 /* Skip ourselves */
1326 if (other
->state
!= DNS_TRANSACTION_PENDING
)
1329 if (other
->next_attempt_after
> ts
)
1332 if (qdcount
>= UINT16_MAX
)
1335 r
= dns_packet_append_key(p
, other
->key
, NULL
);
1338 * If we can't stuff more questions into the packet, just give up.
1339 * One of the 'other' transactions will fire later and take care of the rest.
1347 r
= dns_transaction_prepare(other
, ts
);
1351 ts
+= transaction_get_resend_timeout(other
);
1353 r
= sd_event_add_time(
1354 other
->scope
->manager
->event
,
1355 &other
->timeout_event_source
,
1356 clock_boottime_or_monotonic(),
1358 on_transaction_timeout
, other
);
1362 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1364 other
->state
= DNS_TRANSACTION_PENDING
;
1365 other
->next_attempt_after
= ts
;
1369 if (dns_key_is_shared(other
->key
))
1370 add_known_answers
= true;
1373 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(qdcount
);
1375 /* Append known answer section if we're asking for any shared record */
1376 if (add_known_answers
) {
1377 r
= dns_cache_export_shared_to_packet(&t
->scope
->cache
, p
);
1388 static int dns_transaction_make_packet(DnsTransaction
*t
) {
1389 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1394 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)
1395 return dns_transaction_make_packet_mdns(t
);
1400 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, t
->scope
->dnssec_mode
!= DNSSEC_NO
);
1404 r
= dns_packet_append_key(p
, t
->key
, NULL
);
1408 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
1409 DNS_PACKET_HEADER(p
)->id
= t
->id
;
1417 int dns_transaction_go(DnsTransaction
*t
) {
1420 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1424 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1426 r
= dns_transaction_prepare(t
, ts
);
1430 log_debug("Transaction %" PRIu16
" for <%s> scope %s on %s/%s.",
1432 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
1433 dns_protocol_to_string(t
->scope
->protocol
),
1434 t
->scope
->link
? t
->scope
->link
->name
: "*",
1435 af_to_name_short(t
->scope
->family
));
1437 if (!t
->initial_jitter_scheduled
&&
1438 (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
||
1439 t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)) {
1440 usec_t jitter
, accuracy
;
1442 /* RFC 4795 Section 2.7 suggests all queries should be
1443 * delayed by a random time from 0 to JITTER_INTERVAL. */
1445 t
->initial_jitter_scheduled
= true;
1447 random_bytes(&jitter
, sizeof(jitter
));
1449 switch (t
->scope
->protocol
) {
1451 case DNS_PROTOCOL_LLMNR
:
1452 jitter
%= LLMNR_JITTER_INTERVAL_USEC
;
1453 accuracy
= LLMNR_JITTER_INTERVAL_USEC
;
1456 case DNS_PROTOCOL_MDNS
:
1457 jitter
%= MDNS_JITTER_RANGE_USEC
;
1458 jitter
+= MDNS_JITTER_MIN_USEC
;
1459 accuracy
= MDNS_JITTER_RANGE_USEC
;
1462 assert_not_reached("bad protocol");
1465 r
= sd_event_add_time(
1466 t
->scope
->manager
->event
,
1467 &t
->timeout_event_source
,
1468 clock_boottime_or_monotonic(),
1469 ts
+ jitter
, accuracy
,
1470 on_transaction_timeout
, t
);
1474 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1477 t
->next_attempt_after
= ts
;
1478 t
->state
= DNS_TRANSACTION_PENDING
;
1480 log_debug("Delaying %s transaction for " USEC_FMT
"us.", dns_protocol_to_string(t
->scope
->protocol
), jitter
);
1484 /* Otherwise, we need to ask the network */
1485 r
= dns_transaction_make_packet(t
);
1489 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&&
1490 (dns_name_endswith(dns_resource_key_name(t
->key
), "in-addr.arpa") > 0 ||
1491 dns_name_endswith(dns_resource_key_name(t
->key
), "ip6.arpa") > 0)) {
1493 /* RFC 4795, Section 2.4. says reverse lookups shall
1494 * always be made via TCP on LLMNR */
1495 r
= dns_transaction_open_tcp(t
);
1497 /* Try via UDP, and if that fails due to large size or lack of
1498 * support try via TCP */
1499 r
= dns_transaction_emit_udp(t
);
1501 log_debug("Sending query via TCP since it is too large.");
1503 log_debug("Sending query via TCP since server doesn't support UDP.");
1504 if (r
== -EMSGSIZE
|| r
== -EAGAIN
)
1505 r
= dns_transaction_open_tcp(t
);
1509 /* No servers to send this to? */
1510 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
1513 if (r
== -EOPNOTSUPP
) {
1514 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1515 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
1518 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& ERRNO_IS_DISCONNECT(-r
)) {
1519 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
1520 * answer this request with this protocol. */
1521 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
1525 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1528 /* Couldn't send? Try immediately again, with a new server */
1529 dns_scope_next_dns_server(t
->scope
);
1531 return dns_transaction_go(t
);
1534 ts
+= transaction_get_resend_timeout(t
);
1536 r
= sd_event_add_time(
1537 t
->scope
->manager
->event
,
1538 &t
->timeout_event_source
,
1539 clock_boottime_or_monotonic(),
1541 on_transaction_timeout
, t
);
1545 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1547 t
->state
= DNS_TRANSACTION_PENDING
;
1548 t
->next_attempt_after
= ts
;
1553 static int dns_transaction_find_cyclic(DnsTransaction
*t
, DnsTransaction
*aux
) {
1561 /* Try to find cyclic dependencies between transaction objects */
1566 SET_FOREACH(n
, aux
->dnssec_transactions
, i
) {
1567 r
= dns_transaction_find_cyclic(t
, n
);
1575 static int dns_transaction_add_dnssec_transaction(DnsTransaction
*t
, DnsResourceKey
*key
, DnsTransaction
**ret
) {
1576 DnsTransaction
*aux
;
1583 aux
= dns_scope_find_transaction(t
->scope
, key
, true);
1585 r
= dns_transaction_new(&aux
, t
->scope
, key
);
1589 if (set_contains(t
->dnssec_transactions
, aux
)) {
1594 r
= dns_transaction_find_cyclic(t
, aux
);
1598 char s
[DNS_RESOURCE_KEY_STRING_MAX
], saux
[DNS_RESOURCE_KEY_STRING_MAX
];
1600 log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16
" (%s) as dependency for %" PRIu16
" (%s).",
1602 dns_resource_key_to_string(t
->key
, s
, sizeof s
),
1604 dns_resource_key_to_string(aux
->key
, saux
, sizeof saux
));
1610 r
= set_ensure_allocated(&t
->dnssec_transactions
, NULL
);
1614 r
= set_ensure_allocated(&aux
->notify_transactions
, NULL
);
1618 r
= set_ensure_allocated(&aux
->notify_transactions_done
, NULL
);
1622 r
= set_put(t
->dnssec_transactions
, aux
);
1626 r
= set_put(aux
->notify_transactions
, t
);
1628 (void) set_remove(t
->dnssec_transactions
, aux
);
1636 dns_transaction_gc(aux
);
1640 static int dns_transaction_request_dnssec_rr(DnsTransaction
*t
, DnsResourceKey
*key
) {
1641 _cleanup_(dns_answer_unrefp
) DnsAnswer
*a
= NULL
;
1642 DnsTransaction
*aux
;
1648 /* Try to get the data from the trust anchor */
1649 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, key
, &a
);
1653 r
= dns_answer_extend(&t
->validated_keys
, a
);
1660 /* This didn't work, ask for it via the network/cache then. */
1661 r
= dns_transaction_add_dnssec_transaction(t
, key
, &aux
);
1662 if (r
== -ELOOP
) /* This would result in a cyclic dependency */
1667 if (aux
->state
== DNS_TRANSACTION_NULL
) {
1668 r
= dns_transaction_go(aux
);
1676 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction
*t
, const char *name
) {
1681 /* Check whether the specified name is in the NTA
1682 * database, either in the global one, or the link-local
1685 r
= dns_trust_anchor_lookup_negative(&t
->scope
->manager
->trust_anchor
, name
);
1689 if (!t
->scope
->link
)
1692 return set_contains(t
->scope
->link
->dnssec_negative_trust_anchors
, name
);
1695 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction
*t
) {
1700 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
1701 * RRs to prove it */
1703 r
= dns_transaction_has_positive_answer(t
, NULL
);
1709 /* Is this key explicitly listed as a negative trust anchor?
1710 * If so, it's nothing we need to care about */
1711 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
1717 /* The answer does not contain any RRs that match to the
1718 * question. If so, let's see if there are any NSEC/NSEC3 RRs
1719 * included. If not, the answer is unsigned. */
1721 r
= dns_answer_contains_nsec_or_nsec3(t
->answer
);
1730 static int dns_transaction_is_primary_response(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
1736 /* Check if the specified RR is the "primary" response,
1737 * i.e. either matches the question precisely or is a
1738 * CNAME/DNAME for it. */
1740 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1744 return dns_resource_key_match_cname_or_dname(t
->key
, rr
->key
, NULL
);
1747 static bool dns_transaction_dnssec_supported(DnsTransaction
*t
) {
1750 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
1751 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
1753 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1756 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
1757 * be supported, hence return true. */
1761 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_DO
)
1764 return dns_server_dnssec_supported(t
->server
);
1767 static bool dns_transaction_dnssec_supported_full(DnsTransaction
*t
) {
1773 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
1775 if (!dns_transaction_dnssec_supported(t
))
1778 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
1779 if (!dns_transaction_dnssec_supported(dt
))
1785 int dns_transaction_request_dnssec_keys(DnsTransaction
*t
) {
1786 DnsResourceRecord
*rr
;
1793 * Retrieve all auxiliary RRs for the answer we got, so that
1794 * we can verify signatures or prove that RRs are rightfully
1795 * unsigned. Specifically:
1797 * - For RRSIG we get the matching DNSKEY
1798 * - For DNSKEY we get the matching DS
1799 * - For unsigned SOA/NS we get the matching DS
1800 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
1801 * - For other unsigned RRs we get the matching SOA RR
1802 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
1803 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
1804 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
1807 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
1809 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
1810 return 0; /* We only need to validate stuff from the network */
1811 if (!dns_transaction_dnssec_supported(t
))
1812 return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */
1814 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
1816 if (dns_type_is_pseudo(rr
->key
->type
))
1819 /* If this RR is in the negative trust anchor, we don't need to validate it. */
1820 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
1826 switch (rr
->key
->type
) {
1828 case DNS_TYPE_RRSIG
: {
1829 /* For each RRSIG we request the matching DNSKEY */
1830 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*dnskey
= NULL
;
1832 /* If this RRSIG is about a DNSKEY RR and the
1833 * signer is the same as the owner, then we
1834 * already have the DNSKEY, and we don't have
1835 * to look for more. */
1836 if (rr
->rrsig
.type_covered
== DNS_TYPE_DNSKEY
) {
1837 r
= dns_name_equal(rr
->rrsig
.signer
, dns_resource_key_name(rr
->key
));
1844 /* If the signer is not a parent of our
1845 * original query, then this is about an
1846 * auxiliary RRset, but not anything we asked
1847 * for. In this case we aren't interested,
1848 * because we don't want to request additional
1849 * RRs for stuff we didn't really ask for, and
1850 * also to avoid request loops, where
1851 * additional RRs from one transaction result
1852 * in another transaction whose additonal RRs
1853 * point back to the original transaction, and
1855 r
= dns_name_endswith(dns_resource_key_name(t
->key
), rr
->rrsig
.signer
);
1861 dnskey
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DNSKEY
, rr
->rrsig
.signer
);
1865 log_debug("Requesting DNSKEY to validate transaction %" PRIu16
" (%s, RRSIG with key tag: %" PRIu16
").",
1866 t
->id
, dns_resource_key_name(rr
->key
), rr
->rrsig
.key_tag
);
1867 r
= dns_transaction_request_dnssec_rr(t
, dnskey
);
1873 case DNS_TYPE_DNSKEY
: {
1874 /* For each DNSKEY we request the matching DS */
1875 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1877 /* If the DNSKEY we are looking at is not for
1878 * zone we are interested in, nor any of its
1879 * parents, we aren't interested, and don't
1880 * request it. After all, we don't want to end
1881 * up in request loops, and want to keep
1882 * additional traffic down. */
1884 r
= dns_name_endswith(dns_resource_key_name(t
->key
), dns_resource_key_name(rr
->key
));
1890 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
1894 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, DNSKEY with key tag: %" PRIu16
").",
1895 t
->id
, dns_resource_key_name(rr
->key
), dnssec_keytag(rr
, false));
1896 r
= dns_transaction_request_dnssec_rr(t
, ds
);
1905 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1907 /* For an unsigned SOA or NS, try to acquire
1908 * the matching DS RR, as we are at a zone cut
1909 * then, and whether a DS exists tells us
1910 * whether the zone is signed. Do so only if
1911 * this RR matches our original question,
1914 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1920 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
1926 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
1930 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned SOA/NS RRset).",
1931 t
->id
, dns_resource_key_name(rr
->key
));
1932 r
= dns_transaction_request_dnssec_rr(t
, ds
);
1940 case DNS_TYPE_CNAME
:
1941 case DNS_TYPE_DNAME
: {
1942 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
1945 /* CNAMEs and DNAMEs cannot be located at a
1946 * zone apex, hence ask for the parent SOA for
1947 * unsigned CNAME/DNAME RRs, maybe that's the
1948 * apex. But do all that only if this is
1949 * actually a response to our original
1952 * Similar for DS RRs, which are signed when
1953 * the parent SOA is signed. */
1955 r
= dns_transaction_is_primary_response(t
, rr
);
1961 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
1967 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
1973 name
= dns_resource_key_name(rr
->key
);
1974 r
= dns_name_parent(&name
);
1980 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, name
);
1984 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned CNAME/DNAME/DS RRset).",
1985 t
->id
, dns_resource_key_name(rr
->key
));
1986 r
= dns_transaction_request_dnssec_rr(t
, soa
);
1994 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
1996 /* For other unsigned RRsets (including
1997 * NSEC/NSEC3!), look for proof the zone is
1998 * unsigned, by requesting the SOA RR of the
1999 * zone. However, do so only if they are
2000 * directly relevant to our original
2003 r
= dns_transaction_is_primary_response(t
, rr
);
2009 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2015 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, dns_resource_key_name(rr
->key
));
2019 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned non-SOA/NS RRset <%s>).",
2020 t
->id
, dns_resource_key_name(rr
->key
), dns_resource_record_to_string(rr
));
2021 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2028 /* Above, we requested everything necessary to validate what
2029 * we got. Now, let's request what we need to validate what we
2032 r
= dns_transaction_has_unsigned_negative_answer(t
);
2039 name
= dns_resource_key_name(t
->key
);
2041 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2042 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2043 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2044 * though they have further children. If this was a DS request, then it's signed when the parent zone
2045 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2046 * to see if that is signed. */
2048 if (t
->key
->type
== DNS_TYPE_DS
) {
2049 r
= dns_name_parent(&name
);
2051 type
= DNS_TYPE_SOA
;
2052 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned empty DS response).",
2053 t
->id
, dns_resource_key_name(t
->key
));
2057 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
)) {
2060 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned empty SOA/NS response).",
2061 t
->id
, dns_resource_key_name(t
->key
));
2064 type
= DNS_TYPE_SOA
;
2065 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned empty non-SOA/NS/DS response).",
2066 t
->id
, dns_resource_key_name(t
->key
));
2070 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2072 soa
= dns_resource_key_new(t
->key
->class, type
, name
);
2076 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2082 return dns_transaction_dnssec_is_live(t
);
2085 void dns_transaction_notify(DnsTransaction
*t
, DnsTransaction
*source
) {
2089 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2090 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2091 the state is VALIDATING however, we should check if we are complete now. */
2093 if (t
->state
== DNS_TRANSACTION_VALIDATING
)
2094 dns_transaction_process_dnssec(t
);
2097 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction
*t
) {
2098 DnsResourceRecord
*rr
;
2103 /* Add all DNSKEY RRs from the answer that are validated by DS
2104 * RRs from the list of validated keys to the list of
2105 * validated keys. */
2107 DNS_ANSWER_FOREACH_IFINDEX(rr
, ifindex
, t
->answer
) {
2109 r
= dnssec_verify_dnskey_by_ds_search(rr
, t
->validated_keys
);
2115 /* If so, the DNSKEY is validated too. */
2116 r
= dns_answer_add_extend(&t
->validated_keys
, rr
, ifindex
, DNS_ANSWER_AUTHENTICATED
);
2124 static int dns_transaction_requires_rrsig(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2130 /* Checks if the RR we are looking for must be signed with an
2131 * RRSIG. This is used for positive responses. */
2133 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2136 if (dns_type_is_pseudo(rr
->key
->type
))
2139 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2145 switch (rr
->key
->type
) {
2147 case DNS_TYPE_RRSIG
:
2148 /* RRSIGs are the signatures themselves, they need no signing. */
2156 /* For SOA or NS RRs we look for a matching DS transaction */
2158 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2160 if (dt
->key
->class != rr
->key
->class)
2162 if (dt
->key
->type
!= DNS_TYPE_DS
)
2165 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2171 /* We found a DS transactions for the SOA/NS
2172 * RRs we are looking at. If it discovered signed DS
2173 * RRs, then we need to be signed, too. */
2175 if (!dt
->answer_authenticated
)
2178 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2181 /* We found nothing that proves this is safe to leave
2182 * this unauthenticated, hence ask inist on
2183 * authentication. */
2188 case DNS_TYPE_CNAME
:
2189 case DNS_TYPE_DNAME
: {
2190 const char *parent
= NULL
;
2195 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2197 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2200 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2202 if (dt
->key
->class != rr
->key
->class)
2204 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2208 parent
= dns_resource_key_name(rr
->key
);
2209 r
= dns_name_parent(&parent
);
2213 if (rr
->key
->type
== DNS_TYPE_DS
)
2216 /* A CNAME/DNAME without a parent? That's sooo weird. */
2217 log_debug("Transaction %" PRIu16
" claims CNAME/DNAME at root. Refusing.", t
->id
);
2222 r
= dns_name_equal(dns_resource_key_name(dt
->key
), parent
);
2228 return t
->answer_authenticated
;
2238 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2240 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2242 if (dt
->key
->class != rr
->key
->class)
2244 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2247 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2253 /* We found the transaction that was supposed to find
2254 * the SOA RR for us. It was successful, but found no
2255 * RR for us. This means we are not at a zone cut. In
2256 * this case, we require authentication if the SOA
2257 * lookup was authenticated too. */
2258 return t
->answer_authenticated
;
2265 static int dns_transaction_in_private_tld(DnsTransaction
*t
, const DnsResourceKey
*key
) {
2271 /* If DNSSEC downgrade mode is on, checks whether the
2272 * specified RR is one level below a TLD we have proven not to
2273 * exist. In such a case we assume that this is a private
2274 * domain, and permit it.
2276 * This detects cases like the Fritz!Box router networks. Each
2277 * Fritz!Box router serves a private "fritz.box" zone, in the
2278 * non-existing TLD "box". Requests for the "fritz.box" domain
2279 * are served by the router itself, while requests for the
2280 * "box" domain will result in NXDOMAIN.
2282 * Note that this logic is unable to detect cases where a
2283 * router serves a private DNS zone directly under
2284 * non-existing TLD. In such a case we cannot detect whether
2285 * the TLD is supposed to exist or not, as all requests we
2286 * make for it will be answered by the router's zone, and not
2287 * by the root zone. */
2291 if (t
->scope
->dnssec_mode
!= DNSSEC_ALLOW_DOWNGRADE
)
2292 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2294 tld
= dns_resource_key_name(key
);
2295 r
= dns_name_parent(&tld
);
2299 return false; /* Already the root domain */
2301 if (!dns_name_is_single_label(tld
))
2304 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2306 if (dt
->key
->class != key
->class)
2309 r
= dns_name_equal(dns_resource_key_name(dt
->key
), tld
);
2315 /* We found an auxiliary lookup we did for the TLD. If
2316 * that returned with NXDOMAIN, we know the TLD didn't
2317 * exist, and hence this might be a private zone. */
2319 return dt
->answer_rcode
== DNS_RCODE_NXDOMAIN
;
2325 static int dns_transaction_requires_nsec(DnsTransaction
*t
) {
2326 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2335 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2336 * this negative reply */
2338 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2341 if (dns_type_is_pseudo(t
->key
->type
))
2344 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
2350 r
= dns_transaction_in_private_tld(t
, t
->key
);
2354 /* The lookup is from a TLD that is proven not to
2355 * exist, and we are in downgrade mode, hence ignore
2356 * that fact that we didn't get any NSEC RRs.*/
2358 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2359 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2363 name
= dns_resource_key_name(t
->key
);
2365 if (t
->key
->type
== DNS_TYPE_DS
) {
2367 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2368 * hence check the parent SOA in this case. */
2370 r
= dns_name_parent(&name
);
2376 type
= DNS_TYPE_SOA
;
2378 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
))
2379 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2382 /* For all other negative replies, check for the SOA lookup */
2383 type
= DNS_TYPE_SOA
;
2385 /* For all other RRs we check the SOA on the same level to see
2386 * if it's signed. */
2388 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2390 if (dt
->key
->class != t
->key
->class)
2392 if (dt
->key
->type
!= type
)
2395 r
= dns_name_equal(dns_resource_key_name(dt
->key
), name
);
2401 return dt
->answer_authenticated
;
2404 /* If in doubt, require NSEC/NSEC3 */
2408 static int dns_transaction_dnskey_authenticated(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2409 DnsResourceRecord
*rrsig
;
2413 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2414 * the specified RRset is authenticated (i.e. has a matching
2417 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2423 DNS_ANSWER_FOREACH(rrsig
, t
->answer
) {
2427 r
= dnssec_key_match_rrsig(rr
->key
, rrsig
);
2433 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2435 if (dt
->key
->class != rr
->key
->class)
2438 if (dt
->key
->type
== DNS_TYPE_DNSKEY
) {
2440 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2446 /* OK, we found an auxiliary DNSKEY
2447 * lookup. If that lookup is
2448 * authenticated, report this. */
2450 if (dt
->answer_authenticated
)
2455 } else if (dt
->key
->type
== DNS_TYPE_DS
) {
2457 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2463 /* OK, we found an auxiliary DS
2464 * lookup. If that lookup is
2465 * authenticated and non-zero, we
2468 if (!dt
->answer_authenticated
)
2471 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2476 return found
? false : -ENXIO
;
2479 static int dns_transaction_known_signed(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2483 /* We know that the root domain is signed, hence if it appears
2484 * not to be signed, there's a problem with the DNS server */
2486 return rr
->key
->class == DNS_CLASS_IN
&&
2487 dns_name_is_root(dns_resource_key_name(rr
->key
));
2490 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction
*t
) {
2491 DnsResourceRecord
*rr
;
2496 /* Maybe warn the user that we encountered a revoked DNSKEY
2497 * for a key from our trust anchor. Note that we don't care
2498 * whether the DNSKEY can be authenticated or not. It's
2499 * sufficient if it is self-signed. */
2501 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2502 r
= dns_trust_anchor_check_revoked(&t
->scope
->manager
->trust_anchor
, rr
, t
->answer
);
2510 static int dns_transaction_invalidate_revoked_keys(DnsTransaction
*t
) {
2516 /* Removes all DNSKEY/DS objects from t->validated_keys that
2517 * our trust anchors database considers revoked. */
2520 DnsResourceRecord
*rr
;
2524 DNS_ANSWER_FOREACH(rr
, t
->validated_keys
) {
2525 r
= dns_trust_anchor_is_revoked(&t
->scope
->manager
->trust_anchor
, rr
);
2529 r
= dns_answer_remove_by_rr(&t
->validated_keys
, rr
);
2543 static int dns_transaction_copy_validated(DnsTransaction
*t
) {
2550 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
2552 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2554 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
2557 if (!dt
->answer_authenticated
)
2560 r
= dns_answer_extend(&t
->validated_keys
, dt
->answer
);
2569 DNSSEC_PHASE_DNSKEY
, /* Phase #1, only validate DNSKEYs */
2570 DNSSEC_PHASE_NSEC
, /* Phase #2, only validate NSEC+NSEC3 */
2571 DNSSEC_PHASE_ALL
, /* Phase #3, validate everything else */
2574 static int dnssec_validate_records(
2578 DnsAnswer
**validated
) {
2580 DnsResourceRecord
*rr
;
2583 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
2585 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2586 DnsResourceRecord
*rrsig
= NULL
;
2587 DnssecResult result
;
2589 switch (rr
->key
->type
) {
2590 case DNS_TYPE_RRSIG
:
2593 case DNS_TYPE_DNSKEY
:
2594 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
2595 if (phase
== DNSSEC_PHASE_NSEC
)
2600 case DNS_TYPE_NSEC3
:
2603 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
2604 if (phase
== DNSSEC_PHASE_DNSKEY
)
2609 /* We validate all other RRs only in the ALL phases */
2610 if (phase
!= DNSSEC_PHASE_ALL
)
2614 r
= dnssec_verify_rrset_search(t
->answer
, rr
->key
, t
->validated_keys
, USEC_INFINITY
, &result
, &rrsig
);
2618 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr
)), dnssec_result_to_string(result
));
2620 if (result
== DNSSEC_VALIDATED
) {
2622 if (rr
->key
->type
== DNS_TYPE_DNSKEY
) {
2623 /* If we just validated a DNSKEY RRset, then let's add these keys to
2624 * the set of validated keys for this transaction. */
2626 r
= dns_answer_copy_by_key(&t
->validated_keys
, t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
);
2630 /* Some of the DNSKEYs we just added might already have been revoked,
2631 * remove them again in that case. */
2632 r
= dns_transaction_invalidate_revoked_keys(t
);
2637 /* Add the validated RRset to the new list of validated
2638 * RRsets, and remove it from the unvalidated RRsets.
2639 * We mark the RRset as authenticated and cacheable. */
2640 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
);
2644 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_SECURE
, rr
->key
);
2646 /* Exit the loop, we dropped something from the answer, start from the beginning */
2650 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
2651 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
2652 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
2653 if (phase
!= DNSSEC_PHASE_ALL
)
2656 if (result
== DNSSEC_VALIDATED_WILDCARD
) {
2657 bool authenticated
= false;
2660 /* This RRset validated, but as a wildcard. This means we need
2661 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists.*/
2663 /* First step, determine the source of synthesis */
2664 r
= dns_resource_record_source(rrsig
, &source
);
2668 r
= dnssec_test_positive_wildcard(*validated
,
2669 dns_resource_key_name(rr
->key
),
2671 rrsig
->rrsig
.signer
,
2674 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
2676 result
= DNSSEC_INVALID
;
2678 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
,
2679 authenticated
? (DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
) : 0);
2683 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, rr
->key
);
2685 /* Exit the loop, we dropped something from the answer, start from the beginning */
2690 if (result
== DNSSEC_NO_SIGNATURE
) {
2691 r
= dns_transaction_requires_rrsig(t
, rr
);
2695 /* Data does not require signing. In that case, just copy it over,
2696 * but remember that this is by no means authenticated.*/
2697 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2701 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2705 r
= dns_transaction_known_signed(t
, rr
);
2709 /* This is an RR we know has to be signed. If it isn't this means
2710 * the server is not attaching RRSIGs, hence complain. */
2712 dns_server_packet_rrsig_missing(t
->server
, t
->current_feature_level
);
2714 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
2716 /* Downgrading is OK? If so, just consider the information unsigned */
2718 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2722 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2726 /* Otherwise, fail */
2727 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2731 r
= dns_transaction_in_private_tld(t
, rr
->key
);
2735 char s
[DNS_RESOURCE_KEY_STRING_MAX
];
2737 /* The data is from a TLD that is proven not to exist, and we are in downgrade
2738 * mode, hence ignore the fact that this was not signed. */
2740 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
2741 dns_resource_key_to_string(rr
->key
, s
, sizeof s
));
2743 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2747 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2754 DNSSEC_SIGNATURE_EXPIRED
,
2755 DNSSEC_UNSUPPORTED_ALGORITHM
)) {
2757 r
= dns_transaction_dnskey_authenticated(t
, rr
);
2758 if (r
< 0 && r
!= -ENXIO
)
2761 /* The DNSKEY transaction was not authenticated, this means there's
2762 * no DS for this, which means it's OK if no keys are found for this signature. */
2764 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2768 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2773 r
= dns_transaction_is_primary_response(t
, rr
);
2777 /* Look for a matching DNAME for this CNAME */
2778 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2782 /* Also look among the stuff we already validated */
2783 r
= dns_answer_has_dname_for_cname(*validated
, rr
);
2791 DNSSEC_SIGNATURE_EXPIRED
,
2792 DNSSEC_NO_SIGNATURE
))
2793 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, rr
->key
);
2794 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
2795 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, rr
->key
);
2797 /* This is a primary response to our question, and it failed validation.
2799 t
->answer_dnssec_result
= result
;
2803 /* This is a primary response, but we do have a DNAME RR
2804 * in the RR that can replay this CNAME, hence rely on
2805 * that, and we can remove the CNAME in favour of it. */
2808 /* This is just some auxiliary data. Just remove the RRset and continue. */
2809 r
= dns_answer_remove_by_key(&t
->answer
, rr
->key
);
2813 /* We dropped something from the answer, start from the beginning. */
2817 return 2; /* Finito. */
2820 int dns_transaction_validate_dnssec(DnsTransaction
*t
) {
2821 _cleanup_(dns_answer_unrefp
) DnsAnswer
*validated
= NULL
;
2823 DnsAnswerFlags flags
;
2825 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2829 /* We have now collected all DS and DNSKEY RRs in
2830 * t->validated_keys, let's see which RRs we can now
2831 * authenticate with that. */
2833 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2836 /* Already validated */
2837 if (t
->answer_dnssec_result
!= _DNSSEC_RESULT_INVALID
)
2840 /* Our own stuff needs no validation */
2841 if (IN_SET(t
->answer_source
, DNS_TRANSACTION_ZONE
, DNS_TRANSACTION_TRUST_ANCHOR
)) {
2842 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2843 t
->answer_authenticated
= true;
2847 /* Cached stuff is not affected by validation. */
2848 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
2851 if (!dns_transaction_dnssec_supported_full(t
)) {
2852 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
2853 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2854 log_debug("Not validating response for %" PRIu16
", server lacks DNSSEC support.", t
->id
);
2858 log_debug("Validating response from transaction %" PRIu16
" (%s).",
2860 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2862 /* First, see if this response contains any revoked trust
2863 * anchors we care about */
2864 r
= dns_transaction_check_revoked_trust_anchors(t
);
2868 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
2869 r
= dns_transaction_copy_validated(t
);
2873 /* Second, see if there are DNSKEYs we already know a
2874 * validated DS for. */
2875 r
= dns_transaction_validate_dnskey_by_ds(t
);
2879 /* Fourth, remove all DNSKEY and DS RRs again that our trust
2880 * anchor says are revoked. After all we might have marked
2881 * some keys revoked above, but they might still be lingering
2882 * in our validated_keys list. */
2883 r
= dns_transaction_invalidate_revoked_keys(t
);
2887 phase
= DNSSEC_PHASE_DNSKEY
;
2889 bool have_nsec
= false;
2891 r
= dnssec_validate_records(t
, phase
, &have_nsec
, &validated
);
2895 /* Try again as long as we managed to achieve something */
2899 if (phase
== DNSSEC_PHASE_DNSKEY
&& have_nsec
) {
2900 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
2901 phase
= DNSSEC_PHASE_NSEC
;
2905 if (phase
!= DNSSEC_PHASE_ALL
) {
2906 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
2907 * Note that in this third phase we start to remove RRs we couldn't validate. */
2908 phase
= DNSSEC_PHASE_ALL
;
2916 dns_answer_unref(t
->answer
);
2917 t
->answer
= validated
;
2920 /* At this point the answer only contains validated
2921 * RRsets. Now, let's see if it actually answers the question
2922 * we asked. If so, great! If it doesn't, then see if
2923 * NSEC/NSEC3 can prove this. */
2924 r
= dns_transaction_has_positive_answer(t
, &flags
);
2926 /* Yes, it answers the question! */
2928 if (flags
& DNS_ANSWER_AUTHENTICATED
) {
2929 /* The answer is fully authenticated, yay. */
2930 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2931 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
2932 t
->answer_authenticated
= true;
2934 /* The answer is not fully authenticated. */
2935 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
2936 t
->answer_authenticated
= false;
2939 } else if (r
== 0) {
2940 DnssecNsecResult nr
;
2941 bool authenticated
= false;
2943 /* Bummer! Let's check NSEC/NSEC3 */
2944 r
= dnssec_nsec_test(t
->answer
, t
->key
, &nr
, &authenticated
, &t
->answer_nsec_ttl
);
2950 case DNSSEC_NSEC_NXDOMAIN
:
2951 /* NSEC proves the domain doesn't exist. Very good. */
2952 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
2953 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2954 t
->answer_rcode
= DNS_RCODE_NXDOMAIN
;
2955 t
->answer_authenticated
= authenticated
;
2957 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
2960 case DNSSEC_NSEC_NODATA
:
2961 /* NSEC proves that there's no data here, very good. */
2962 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
2963 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2964 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
2965 t
->answer_authenticated
= authenticated
;
2967 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
2970 case DNSSEC_NSEC_OPTOUT
:
2971 /* NSEC3 says the data might not be signed */
2972 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
2973 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
2974 t
->answer_authenticated
= false;
2976 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
2979 case DNSSEC_NSEC_NO_RR
:
2980 /* No NSEC data? Bummer! */
2982 r
= dns_transaction_requires_nsec(t
);
2986 t
->answer_dnssec_result
= DNSSEC_NO_SIGNATURE
;
2987 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
2989 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
2990 t
->answer_authenticated
= false;
2991 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
2996 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM
:
2997 /* We don't know the NSEC3 algorithm used? */
2998 t
->answer_dnssec_result
= DNSSEC_UNSUPPORTED_ALGORITHM
;
2999 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, t
->key
);
3002 case DNSSEC_NSEC_FOUND
:
3003 case DNSSEC_NSEC_CNAME
:
3004 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3005 t
->answer_dnssec_result
= DNSSEC_NSEC_MISMATCH
;
3006 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3010 assert_not_reached("Unexpected NSEC result.");
3017 static const char* const dns_transaction_state_table
[_DNS_TRANSACTION_STATE_MAX
] = {
3018 [DNS_TRANSACTION_NULL
] = "null",
3019 [DNS_TRANSACTION_PENDING
] = "pending",
3020 [DNS_TRANSACTION_VALIDATING
] = "validating",
3021 [DNS_TRANSACTION_RCODE_FAILURE
] = "rcode-failure",
3022 [DNS_TRANSACTION_SUCCESS
] = "success",
3023 [DNS_TRANSACTION_NO_SERVERS
] = "no-servers",
3024 [DNS_TRANSACTION_TIMEOUT
] = "timeout",
3025 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
] = "attempts-max-reached",
3026 [DNS_TRANSACTION_INVALID_REPLY
] = "invalid-reply",
3027 [DNS_TRANSACTION_ERRNO
] = "errno",
3028 [DNS_TRANSACTION_ABORTED
] = "aborted",
3029 [DNS_TRANSACTION_DNSSEC_FAILED
] = "dnssec-failed",
3030 [DNS_TRANSACTION_NO_TRUST_ANCHOR
] = "no-trust-anchor",
3031 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
] = "rr-type-unsupported",
3032 [DNS_TRANSACTION_NETWORK_DOWN
] = "network-down",
3033 [DNS_TRANSACTION_NOT_FOUND
] = "not-found",
3035 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state
, DnsTransactionState
);
3037 static const char* const dns_transaction_source_table
[_DNS_TRANSACTION_SOURCE_MAX
] = {
3038 [DNS_TRANSACTION_NETWORK
] = "network",
3039 [DNS_TRANSACTION_CACHE
] = "cache",
3040 [DNS_TRANSACTION_ZONE
] = "zone",
3041 [DNS_TRANSACTION_TRUST_ANCHOR
] = "trust-anchor",
3043 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source
, DnsTransactionSource
);