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
) {
411 /* Returns > 0 if the transaction was restarted, 0 if not */
416 if (t
->current_feature_level
<= dns_server_possible_feature_level(t
->server
))
419 /* The server's current feature level is lower than when we sent the original query. We learnt something from
420 the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to
421 restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include
422 OPT RR or DO bit. One of these cases is documented here, for example:
423 https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
425 log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
426 dns_transaction_shuffle_id(t
);
428 r
= dns_transaction_go(t
);
435 static int on_stream_complete(DnsStream
*s
, int error
) {
436 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
440 assert(s
->transaction
);
442 /* Copy the data we care about out of the stream before we
445 p
= dns_packet_ref(s
->read_packet
);
447 t
->stream
= dns_stream_free(t
->stream
);
449 if (ERRNO_IS_DISCONNECT(error
)) {
452 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
) {
453 /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the
454 * question on this scope. */
455 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
459 log_debug_errno(error
, "Connection failure for DNS TCP stream: %m");
460 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
461 dns_server_packet_lost(t
->server
, IPPROTO_TCP
, t
->current_feature_level
, usec
- t
->start_usec
);
463 dns_transaction_retry(t
);
467 t
->answer_errno
= error
;
468 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
472 if (dns_packet_validate_reply(p
) <= 0) {
473 log_debug("Invalid TCP reply packet.");
474 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
478 dns_scope_check_conflicts(t
->scope
, p
);
481 dns_transaction_process_reply(t
, p
);
484 /* If the response wasn't useful, then complete the transition
485 * now. After all, we are the worst feature set now with TCP
486 * sockets, and there's really no point in retrying. */
487 if (t
->state
== DNS_TRANSACTION_PENDING
)
488 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
490 dns_transaction_gc(t
);
495 static int dns_transaction_open_tcp(DnsTransaction
*t
) {
496 _cleanup_close_
int fd
= -1;
501 dns_transaction_close_connection(t
);
503 switch (t
->scope
->protocol
) {
505 case DNS_PROTOCOL_DNS
:
506 r
= dns_transaction_pick_server(t
);
510 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
513 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
517 fd
= dns_scope_socket_tcp(t
->scope
, AF_UNSPEC
, NULL
, t
->server
, 53);
520 case DNS_PROTOCOL_LLMNR
:
521 /* When we already received a reply to this (but it was truncated), send to its sender address */
523 fd
= dns_scope_socket_tcp(t
->scope
, t
->received
->family
, &t
->received
->sender
, NULL
, t
->received
->sender_port
);
525 union in_addr_union address
;
526 int family
= AF_UNSPEC
;
528 /* Otherwise, try to talk to the owner of a
529 * the IP address, in case this is a reverse
532 r
= dns_name_address(dns_resource_key_name(t
->key
), &family
, &address
);
537 if (family
!= t
->scope
->family
)
540 fd
= dns_scope_socket_tcp(t
->scope
, family
, &address
, NULL
, LLMNR_PORT
);
546 return -EAFNOSUPPORT
;
552 r
= dns_stream_new(t
->scope
->manager
, &t
->stream
, t
->scope
->protocol
, fd
);
557 r
= dns_stream_write_packet(t
->stream
, t
->sent
);
559 t
->stream
= dns_stream_free(t
->stream
);
563 t
->stream
->complete
= on_stream_complete
;
564 t
->stream
->transaction
= t
;
566 /* The interface index is difficult to determine if we are
567 * connecting to the local host, hence fill this in right away
568 * instead of determining it from the socket */
569 t
->stream
->ifindex
= dns_scope_ifindex(t
->scope
);
571 dns_transaction_reset_answer(t
);
573 t
->tried_stream
= true;
578 static void dns_transaction_cache_answer(DnsTransaction
*t
) {
581 /* For mDNS we cache whenever we get the packet, rather than
582 * in each transaction. */
583 if (!IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
))
586 /* We never cache if this packet is from the local host, under
587 * the assumption that a locally running DNS server would
588 * cache this anyway, and probably knows better when to flush
589 * the cache then we could. */
590 if (!DNS_PACKET_SHALL_CACHE(t
->received
))
593 dns_cache_put(&t
->scope
->cache
,
597 t
->answer_authenticated
,
601 &t
->received
->sender
);
604 static bool dns_transaction_dnssec_is_live(DnsTransaction
*t
) {
610 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
611 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
617 static int dns_transaction_dnssec_ready(DnsTransaction
*t
) {
623 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
624 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
626 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
630 case DNS_TRANSACTION_NULL
:
631 case DNS_TRANSACTION_PENDING
:
632 case DNS_TRANSACTION_VALIDATING
:
636 case DNS_TRANSACTION_RCODE_FAILURE
:
637 if (dt
->answer_rcode
!= DNS_RCODE_NXDOMAIN
) {
638 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt
->answer_rcode
));
642 /* Fall-through: NXDOMAIN is good enough for us. This is because some DNS servers erronously
643 * return NXDOMAIN for empty non-terminals (Akamai...), and we need to handle that nicely, when
644 * asking for parent SOA or similar RRs to make unsigned proofs. */
646 case DNS_TRANSACTION_SUCCESS
:
650 case DNS_TRANSACTION_DNSSEC_FAILED
:
651 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
652 * validationr result */
654 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt
->answer_dnssec_result
));
655 t
->answer_dnssec_result
= dt
->answer_dnssec_result
; /* Copy error code over */
656 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
661 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt
->state
));
666 /* All is ready, we can go and validate */
670 t
->answer_dnssec_result
= DNSSEC_FAILED_AUXILIARY
;
671 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
675 static void dns_transaction_process_dnssec(DnsTransaction
*t
) {
680 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
681 r
= dns_transaction_dnssec_ready(t
);
684 if (r
== 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
687 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
688 * restart the lookup immediately. */
689 r
= dns_transaction_maybe_restart(t
);
692 if (r
> 0) /* Transaction got restarted... */
695 /* All our auxiliary DNSSEC transactions are complete now. Try
696 * to validate our RRset now. */
697 r
= dns_transaction_validate_dnssec(t
);
699 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
705 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
&&
706 t
->scope
->dnssec_mode
== DNSSEC_YES
) {
707 /* We are not in automatic downgrade mode, and the
708 * server is bad, refuse operation. */
709 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
713 if (!IN_SET(t
->answer_dnssec_result
,
714 _DNSSEC_RESULT_INVALID
, /* No DNSSEC validation enabled */
715 DNSSEC_VALIDATED
, /* Answer is signed and validated successfully */
716 DNSSEC_UNSIGNED
, /* Answer is right-fully unsigned */
717 DNSSEC_INCOMPATIBLE_SERVER
)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
718 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
722 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
)
723 dns_server_warn_downgrade(t
->server
);
725 dns_transaction_cache_answer(t
);
727 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
728 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
730 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
735 t
->answer_errno
= -r
;
736 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
739 static int dns_transaction_has_positive_answer(DnsTransaction
*t
, DnsAnswerFlags
*flags
) {
744 /* Checks whether the answer is positive, i.e. either a direct
745 * answer to the question, or a CNAME/DNAME for it */
747 r
= dns_answer_match_key(t
->answer
, t
->key
, flags
);
751 r
= dns_answer_find_cname_or_dname(t
->answer
, t
->key
, NULL
, flags
);
758 static int dns_transaction_fix_rcode(DnsTransaction
*t
) {
763 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
764 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
765 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
766 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
767 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
768 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
769 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
770 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
771 * incomplete CNAME/DNAME chain.
773 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
774 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
777 if (t
->answer_rcode
!= DNS_RCODE_NXDOMAIN
)
780 r
= dns_transaction_has_positive_answer(t
, NULL
);
784 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
788 void dns_transaction_process_reply(DnsTransaction
*t
, DnsPacket
*p
) {
795 assert(t
->scope
->manager
);
797 if (t
->state
!= DNS_TRANSACTION_PENDING
)
800 /* Note that this call might invalidate the query. Callers
801 * should hence not attempt to access the query or transaction
802 * after calling this function. */
804 log_debug("Processing incoming packet on transaction %" PRIu16
".", t
->id
);
806 switch (t
->scope
->protocol
) {
808 case DNS_PROTOCOL_LLMNR
:
809 /* For LLMNR we will not accept any packets from other interfaces */
811 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
814 if (p
->family
!= t
->scope
->family
)
817 /* Tentative packets are not full responses but still
818 * useful for identifying uniqueness conflicts during
820 if (DNS_PACKET_LLMNR_T(p
)) {
821 dns_transaction_tentative(t
, p
);
827 case DNS_PROTOCOL_MDNS
:
828 /* For mDNS we will not accept any packets from other interfaces */
830 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
833 if (p
->family
!= t
->scope
->family
)
838 case DNS_PROTOCOL_DNS
:
839 /* Note that we do not need to verify the
840 * addresses/port numbers of incoming traffic, as we
841 * invoked connect() on our UDP socket in which case
842 * the kernel already does the needed verification for
847 assert_not_reached("Invalid DNS protocol.");
850 if (t
->received
!= p
) {
851 dns_packet_unref(t
->received
);
852 t
->received
= dns_packet_ref(p
);
855 t
->answer_source
= DNS_TRANSACTION_NETWORK
;
857 if (p
->ipproto
== IPPROTO_TCP
) {
858 if (DNS_PACKET_TC(p
)) {
859 /* Truncated via TCP? Somebody must be fucking with us */
860 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
864 if (DNS_PACKET_ID(p
) != t
->id
) {
865 /* Not the reply to our query? Somebody must be fucking with us */
866 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
871 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
873 switch (t
->scope
->protocol
) {
875 case DNS_PROTOCOL_DNS
:
878 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_FORMERR
, DNS_RCODE_SERVFAIL
, DNS_RCODE_NOTIMP
)) {
880 /* Request failed, immediately try again with reduced features */
881 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
883 dns_server_packet_failed(t
->server
, t
->current_feature_level
);
884 dns_transaction_retry(t
);
886 } else if (DNS_PACKET_TC(p
))
887 dns_server_packet_truncated(t
->server
, t
->current_feature_level
);
891 case DNS_PROTOCOL_LLMNR
:
892 case DNS_PROTOCOL_MDNS
:
893 dns_scope_packet_received(t
->scope
, ts
- t
->start_usec
);
897 assert_not_reached("Invalid DNS protocol.");
900 if (DNS_PACKET_TC(p
)) {
902 /* Truncated packets for mDNS are not allowed. Give up immediately. */
903 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
) {
904 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
908 log_debug("Reply truncated, retrying via TCP.");
910 /* Response was truncated, let's try again with good old TCP */
911 r
= dns_transaction_open_tcp(t
);
913 /* No servers found? Damn! */
914 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
917 if (r
== -EOPNOTSUPP
) {
918 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
919 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
923 /* On LLMNR, if we cannot connect to the host,
924 * we immediately give up */
925 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
928 /* On DNS, couldn't send? Try immediately again, with a new server */
929 dns_transaction_retry(t
);
935 /* After the superficial checks, actually parse the message. */
936 r
= dns_packet_extract(p
);
938 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
942 /* Report that the OPT RR was missing */
945 dns_server_packet_bad_opt(t
->server
, t
->current_feature_level
);
947 dns_server_packet_received(t
->server
, p
->ipproto
, t
->current_feature_level
, ts
- t
->start_usec
, p
->size
);
950 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
951 r
= dns_transaction_maybe_restart(t
);
954 if (r
> 0) /* Transaction got restarted... */
957 if (IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
)) {
959 /* Only consider responses with equivalent query section to the request */
960 r
= dns_packet_is_reply_for(p
, t
->key
);
964 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
968 /* Install the answer as answer to the transaction */
969 dns_answer_unref(t
->answer
);
970 t
->answer
= dns_answer_ref(p
->answer
);
971 t
->answer_rcode
= DNS_PACKET_RCODE(p
);
972 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
973 t
->answer_authenticated
= false;
975 r
= dns_transaction_fix_rcode(t
);
979 /* Block GC while starting requests for additional DNSSEC RRs */
981 r
= dns_transaction_request_dnssec_keys(t
);
984 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
985 if (!dns_transaction_gc(t
))
988 /* Requesting additional keys might have resulted in
989 * this transaction to fail, since the auxiliary
990 * request failed for some reason. If so, we are not
991 * in pending state anymore, and we should exit
993 if (t
->state
!= DNS_TRANSACTION_PENDING
)
998 /* There are DNSSEC transactions pending now. Update the state accordingly. */
999 t
->state
= DNS_TRANSACTION_VALIDATING
;
1000 dns_transaction_close_connection(t
);
1001 dns_transaction_stop_timeout(t
);
1006 dns_transaction_process_dnssec(t
);
1010 t
->answer_errno
= -r
;
1011 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1014 static int on_dns_packet(sd_event_source
*s
, int fd
, uint32_t revents
, void *userdata
) {
1015 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1016 DnsTransaction
*t
= userdata
;
1022 r
= manager_recv(t
->scope
->manager
, fd
, DNS_PROTOCOL_DNS
, &p
);
1023 if (ERRNO_IS_DISCONNECT(-r
)) {
1026 /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next
1027 * recvmsg(). Treat this like a lost packet. */
1029 log_debug_errno(r
, "Connection failure for DNS UDP packet: %m");
1030 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
1031 dns_server_packet_lost(t
->server
, IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1033 dns_transaction_retry(t
);
1037 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1038 t
->answer_errno
= -r
;
1042 r
= dns_packet_validate_reply(p
);
1044 log_debug_errno(r
, "Received invalid DNS packet as response, ignoring: %m");
1048 log_debug("Received inappropriate DNS packet as response, ignoring.");
1052 if (DNS_PACKET_ID(p
) != t
->id
) {
1053 log_debug("Received packet with incorrect transaction ID, ignoring.");
1057 dns_transaction_process_reply(t
, p
);
1061 static int dns_transaction_emit_udp(DnsTransaction
*t
) {
1066 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1068 r
= dns_transaction_pick_server(t
);
1072 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_UDP
)
1075 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
1078 if (r
> 0 || t
->dns_udp_fd
< 0) { /* Server changed, or no connection yet. */
1081 dns_transaction_close_connection(t
);
1083 fd
= dns_scope_socket_udp(t
->scope
, t
->server
, 53);
1087 r
= sd_event_add_io(t
->scope
->manager
->event
, &t
->dns_udp_event_source
, fd
, EPOLLIN
, on_dns_packet
, t
);
1093 (void) sd_event_source_set_description(t
->dns_udp_event_source
, "dns-transaction-udp");
1097 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
1101 dns_transaction_close_connection(t
);
1103 r
= dns_scope_emit_udp(t
->scope
, t
->dns_udp_fd
, t
->sent
);
1107 dns_transaction_reset_answer(t
);
1112 static int on_transaction_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1113 DnsTransaction
*t
= userdata
;
1118 if (!t
->initial_jitter_scheduled
|| t
->initial_jitter_elapsed
) {
1119 /* Timeout reached? Increase the timeout for the server used */
1120 switch (t
->scope
->protocol
) {
1122 case DNS_PROTOCOL_DNS
:
1124 dns_server_packet_lost(t
->server
, t
->stream
? IPPROTO_TCP
: IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1127 case DNS_PROTOCOL_LLMNR
:
1128 case DNS_PROTOCOL_MDNS
:
1129 dns_scope_packet_lost(t
->scope
, usec
- t
->start_usec
);
1133 assert_not_reached("Invalid DNS protocol.");
1136 if (t
->initial_jitter_scheduled
)
1137 t
->initial_jitter_elapsed
= true;
1140 log_debug("Timeout reached on transaction %" PRIu16
".", t
->id
);
1142 dns_transaction_retry(t
);
1146 static usec_t
transaction_get_resend_timeout(DnsTransaction
*t
) {
1150 switch (t
->scope
->protocol
) {
1152 case DNS_PROTOCOL_DNS
:
1154 return t
->server
->resend_timeout
;
1156 case DNS_PROTOCOL_MDNS
:
1157 assert(t
->n_attempts
> 0);
1158 return (1 << (t
->n_attempts
- 1)) * USEC_PER_SEC
;
1160 case DNS_PROTOCOL_LLMNR
:
1161 return t
->scope
->resend_timeout
;
1164 assert_not_reached("Invalid DNS protocol.");
1168 static int dns_transaction_prepare(DnsTransaction
*t
, usec_t ts
) {
1173 dns_transaction_stop_timeout(t
);
1175 r
= dns_scope_network_good(t
->scope
);
1179 dns_transaction_complete(t
, DNS_TRANSACTION_NETWORK_DOWN
);
1183 if (t
->n_attempts
>= TRANSACTION_ATTEMPTS_MAX(t
->scope
->protocol
)) {
1184 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1188 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& t
->tried_stream
) {
1189 /* If we already tried via a stream, then we don't
1190 * retry on LLMNR. See RFC 4795, Section 2.7. */
1191 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1198 dns_transaction_reset_answer(t
);
1199 dns_transaction_flush_dnssec_transactions(t
);
1201 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1202 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1203 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, t
->key
, &t
->answer
);
1207 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1208 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1209 t
->answer_authenticated
= true;
1210 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1214 if (dns_name_is_root(dns_resource_key_name(t
->key
)) &&
1215 t
->key
->type
== DNS_TYPE_DS
) {
1217 /* Hmm, this is a request for the root DS? A
1218 * DS RR doesn't exist in the root zone, and
1219 * if our trust anchor didn't know it either,
1220 * this means we cannot do any DNSSEC logic
1223 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
1224 /* We are in downgrade mode. In this
1225 * case, synthesize an unsigned empty
1226 * response, so that the any lookup
1227 * depending on this one can continue
1228 * assuming there was no DS, and hence
1229 * the root zone was unsigned. */
1231 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1232 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1233 t
->answer_authenticated
= false;
1234 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1236 /* If we are not in downgrade mode,
1237 * then fail the lookup, because we
1238 * cannot reasonably answer it. There
1239 * might be DS RRs, but we don't know
1240 * them, and the DNS server won't tell
1241 * them to us (and even if it would,
1242 * we couldn't validate and trust them. */
1243 dns_transaction_complete(t
, DNS_TRANSACTION_NO_TRUST_ANCHOR
);
1249 /* Check the zone, but only if this transaction is not used
1250 * for probing or verifying a zone item. */
1251 if (set_isempty(t
->notify_zone_items
)) {
1253 r
= dns_zone_lookup(&t
->scope
->zone
, t
->key
, dns_scope_ifindex(t
->scope
), &t
->answer
, NULL
, NULL
);
1257 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1258 t
->answer_source
= DNS_TRANSACTION_ZONE
;
1259 t
->answer_authenticated
= true;
1260 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1265 /* Check the cache, but only if this transaction is not used
1266 * for probing or verifying a zone item. */
1267 if (set_isempty(t
->notify_zone_items
)) {
1269 /* Before trying the cache, let's make sure we figured out a
1270 * server to use. Should this cause a change of server this
1271 * might flush the cache. */
1272 dns_scope_get_dns_server(t
->scope
);
1274 /* Let's then prune all outdated entries */
1275 dns_cache_prune(&t
->scope
->cache
);
1277 r
= dns_cache_lookup(&t
->scope
->cache
, t
->key
, t
->clamp_ttl
, &t
->answer_rcode
, &t
->answer
, &t
->answer_authenticated
);
1281 t
->answer_source
= DNS_TRANSACTION_CACHE
;
1282 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
1283 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1285 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
1293 static int dns_transaction_make_packet_mdns(DnsTransaction
*t
) {
1295 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1296 bool add_known_answers
= false;
1297 DnsTransaction
*other
;
1303 assert(t
->scope
->protocol
== DNS_PROTOCOL_MDNS
);
1305 /* Discard any previously prepared packet, so we can start over and coalesce again */
1306 t
->sent
= dns_packet_unref(t
->sent
);
1308 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, false);
1312 r
= dns_packet_append_key(p
, t
->key
, NULL
);
1318 if (dns_key_is_shared(t
->key
))
1319 add_known_answers
= true;
1322 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1323 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1324 * in our current scope, and see whether their timing contraints allow them to be sent.
1327 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1329 LIST_FOREACH(transactions_by_scope
, other
, t
->scope
->transactions
) {
1331 /* Skip ourselves */
1335 if (other
->state
!= DNS_TRANSACTION_PENDING
)
1338 if (other
->next_attempt_after
> ts
)
1341 if (qdcount
>= UINT16_MAX
)
1344 r
= dns_packet_append_key(p
, other
->key
, NULL
);
1347 * If we can't stuff more questions into the packet, just give up.
1348 * One of the 'other' transactions will fire later and take care of the rest.
1356 r
= dns_transaction_prepare(other
, ts
);
1360 ts
+= transaction_get_resend_timeout(other
);
1362 r
= sd_event_add_time(
1363 other
->scope
->manager
->event
,
1364 &other
->timeout_event_source
,
1365 clock_boottime_or_monotonic(),
1367 on_transaction_timeout
, other
);
1371 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1373 other
->state
= DNS_TRANSACTION_PENDING
;
1374 other
->next_attempt_after
= ts
;
1378 if (dns_key_is_shared(other
->key
))
1379 add_known_answers
= true;
1382 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(qdcount
);
1384 /* Append known answer section if we're asking for any shared record */
1385 if (add_known_answers
) {
1386 r
= dns_cache_export_shared_to_packet(&t
->scope
->cache
, p
);
1397 static int dns_transaction_make_packet(DnsTransaction
*t
) {
1398 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1403 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)
1404 return dns_transaction_make_packet_mdns(t
);
1409 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, t
->scope
->dnssec_mode
!= DNSSEC_NO
);
1413 r
= dns_packet_append_key(p
, t
->key
, NULL
);
1417 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
1418 DNS_PACKET_HEADER(p
)->id
= t
->id
;
1426 int dns_transaction_go(DnsTransaction
*t
) {
1429 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1433 /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has finished
1436 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1438 r
= dns_transaction_prepare(t
, ts
);
1442 log_debug("Transaction %" PRIu16
" for <%s> scope %s on %s/%s.",
1444 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
1445 dns_protocol_to_string(t
->scope
->protocol
),
1446 t
->scope
->link
? t
->scope
->link
->name
: "*",
1447 af_to_name_short(t
->scope
->family
));
1449 if (!t
->initial_jitter_scheduled
&&
1450 (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
||
1451 t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)) {
1452 usec_t jitter
, accuracy
;
1454 /* RFC 4795 Section 2.7 suggests all queries should be
1455 * delayed by a random time from 0 to JITTER_INTERVAL. */
1457 t
->initial_jitter_scheduled
= true;
1459 random_bytes(&jitter
, sizeof(jitter
));
1461 switch (t
->scope
->protocol
) {
1463 case DNS_PROTOCOL_LLMNR
:
1464 jitter
%= LLMNR_JITTER_INTERVAL_USEC
;
1465 accuracy
= LLMNR_JITTER_INTERVAL_USEC
;
1468 case DNS_PROTOCOL_MDNS
:
1469 jitter
%= MDNS_JITTER_RANGE_USEC
;
1470 jitter
+= MDNS_JITTER_MIN_USEC
;
1471 accuracy
= MDNS_JITTER_RANGE_USEC
;
1474 assert_not_reached("bad protocol");
1477 r
= sd_event_add_time(
1478 t
->scope
->manager
->event
,
1479 &t
->timeout_event_source
,
1480 clock_boottime_or_monotonic(),
1481 ts
+ jitter
, accuracy
,
1482 on_transaction_timeout
, t
);
1486 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1489 t
->next_attempt_after
= ts
;
1490 t
->state
= DNS_TRANSACTION_PENDING
;
1492 log_debug("Delaying %s transaction for " USEC_FMT
"us.", dns_protocol_to_string(t
->scope
->protocol
), jitter
);
1496 /* Otherwise, we need to ask the network */
1497 r
= dns_transaction_make_packet(t
);
1501 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&&
1502 (dns_name_endswith(dns_resource_key_name(t
->key
), "in-addr.arpa") > 0 ||
1503 dns_name_endswith(dns_resource_key_name(t
->key
), "ip6.arpa") > 0)) {
1505 /* RFC 4795, Section 2.4. says reverse lookups shall
1506 * always be made via TCP on LLMNR */
1507 r
= dns_transaction_open_tcp(t
);
1509 /* Try via UDP, and if that fails due to large size or lack of
1510 * support try via TCP */
1511 r
= dns_transaction_emit_udp(t
);
1513 log_debug("Sending query via TCP since it is too large.");
1515 log_debug("Sending query via TCP since server doesn't support UDP.");
1516 if (r
== -EMSGSIZE
|| r
== -EAGAIN
)
1517 r
= dns_transaction_open_tcp(t
);
1521 /* No servers to send this to? */
1522 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
1525 if (r
== -EOPNOTSUPP
) {
1526 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1527 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
1530 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& ERRNO_IS_DISCONNECT(-r
)) {
1531 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
1532 * answer this request with this protocol. */
1533 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
1537 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1540 /* Couldn't send? Try immediately again, with a new server */
1541 dns_scope_next_dns_server(t
->scope
);
1543 return dns_transaction_go(t
);
1546 ts
+= transaction_get_resend_timeout(t
);
1548 r
= sd_event_add_time(
1549 t
->scope
->manager
->event
,
1550 &t
->timeout_event_source
,
1551 clock_boottime_or_monotonic(),
1553 on_transaction_timeout
, t
);
1557 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1559 t
->state
= DNS_TRANSACTION_PENDING
;
1560 t
->next_attempt_after
= ts
;
1565 static int dns_transaction_find_cyclic(DnsTransaction
*t
, DnsTransaction
*aux
) {
1573 /* Try to find cyclic dependencies between transaction objects */
1578 SET_FOREACH(n
, aux
->dnssec_transactions
, i
) {
1579 r
= dns_transaction_find_cyclic(t
, n
);
1587 static int dns_transaction_add_dnssec_transaction(DnsTransaction
*t
, DnsResourceKey
*key
, DnsTransaction
**ret
) {
1588 DnsTransaction
*aux
;
1595 aux
= dns_scope_find_transaction(t
->scope
, key
, true);
1597 r
= dns_transaction_new(&aux
, t
->scope
, key
);
1601 if (set_contains(t
->dnssec_transactions
, aux
)) {
1606 r
= dns_transaction_find_cyclic(t
, aux
);
1610 char s
[DNS_RESOURCE_KEY_STRING_MAX
], saux
[DNS_RESOURCE_KEY_STRING_MAX
];
1612 log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16
" (%s) as dependency for %" PRIu16
" (%s).",
1614 dns_resource_key_to_string(t
->key
, s
, sizeof s
),
1616 dns_resource_key_to_string(aux
->key
, saux
, sizeof saux
));
1622 r
= set_ensure_allocated(&t
->dnssec_transactions
, NULL
);
1626 r
= set_ensure_allocated(&aux
->notify_transactions
, NULL
);
1630 r
= set_ensure_allocated(&aux
->notify_transactions_done
, NULL
);
1634 r
= set_put(t
->dnssec_transactions
, aux
);
1638 r
= set_put(aux
->notify_transactions
, t
);
1640 (void) set_remove(t
->dnssec_transactions
, aux
);
1648 dns_transaction_gc(aux
);
1652 static int dns_transaction_request_dnssec_rr(DnsTransaction
*t
, DnsResourceKey
*key
) {
1653 _cleanup_(dns_answer_unrefp
) DnsAnswer
*a
= NULL
;
1654 DnsTransaction
*aux
;
1660 /* Try to get the data from the trust anchor */
1661 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, key
, &a
);
1665 r
= dns_answer_extend(&t
->validated_keys
, a
);
1672 /* This didn't work, ask for it via the network/cache then. */
1673 r
= dns_transaction_add_dnssec_transaction(t
, key
, &aux
);
1674 if (r
== -ELOOP
) /* This would result in a cyclic dependency */
1679 if (aux
->state
== DNS_TRANSACTION_NULL
) {
1680 r
= dns_transaction_go(aux
);
1688 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction
*t
, const char *name
) {
1693 /* Check whether the specified name is in the NTA
1694 * database, either in the global one, or the link-local
1697 r
= dns_trust_anchor_lookup_negative(&t
->scope
->manager
->trust_anchor
, name
);
1701 if (!t
->scope
->link
)
1704 return set_contains(t
->scope
->link
->dnssec_negative_trust_anchors
, name
);
1707 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction
*t
) {
1712 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
1713 * RRs to prove it */
1715 r
= dns_transaction_has_positive_answer(t
, NULL
);
1721 /* Is this key explicitly listed as a negative trust anchor?
1722 * If so, it's nothing we need to care about */
1723 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
1729 /* The answer does not contain any RRs that match to the
1730 * question. If so, let's see if there are any NSEC/NSEC3 RRs
1731 * included. If not, the answer is unsigned. */
1733 r
= dns_answer_contains_nsec_or_nsec3(t
->answer
);
1742 static int dns_transaction_is_primary_response(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
1748 /* Check if the specified RR is the "primary" response,
1749 * i.e. either matches the question precisely or is a
1750 * CNAME/DNAME for it. */
1752 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1756 return dns_resource_key_match_cname_or_dname(t
->key
, rr
->key
, NULL
);
1759 static bool dns_transaction_dnssec_supported(DnsTransaction
*t
) {
1762 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
1763 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
1765 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1768 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
1769 * be supported, hence return true. */
1773 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_DO
)
1776 return dns_server_dnssec_supported(t
->server
);
1779 static bool dns_transaction_dnssec_supported_full(DnsTransaction
*t
) {
1785 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
1787 if (!dns_transaction_dnssec_supported(t
))
1790 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
1791 if (!dns_transaction_dnssec_supported(dt
))
1797 int dns_transaction_request_dnssec_keys(DnsTransaction
*t
) {
1798 DnsResourceRecord
*rr
;
1805 * Retrieve all auxiliary RRs for the answer we got, so that
1806 * we can verify signatures or prove that RRs are rightfully
1807 * unsigned. Specifically:
1809 * - For RRSIG we get the matching DNSKEY
1810 * - For DNSKEY we get the matching DS
1811 * - For unsigned SOA/NS we get the matching DS
1812 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
1813 * - For other unsigned RRs we get the matching SOA RR
1814 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
1815 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
1816 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
1819 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
1821 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
1822 return 0; /* We only need to validate stuff from the network */
1823 if (!dns_transaction_dnssec_supported(t
))
1824 return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */
1826 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
1828 if (dns_type_is_pseudo(rr
->key
->type
))
1831 /* If this RR is in the negative trust anchor, we don't need to validate it. */
1832 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
1838 switch (rr
->key
->type
) {
1840 case DNS_TYPE_RRSIG
: {
1841 /* For each RRSIG we request the matching DNSKEY */
1842 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*dnskey
= NULL
;
1844 /* If this RRSIG is about a DNSKEY RR and the
1845 * signer is the same as the owner, then we
1846 * already have the DNSKEY, and we don't have
1847 * to look for more. */
1848 if (rr
->rrsig
.type_covered
== DNS_TYPE_DNSKEY
) {
1849 r
= dns_name_equal(rr
->rrsig
.signer
, dns_resource_key_name(rr
->key
));
1856 /* If the signer is not a parent of our
1857 * original query, then this is about an
1858 * auxiliary RRset, but not anything we asked
1859 * for. In this case we aren't interested,
1860 * because we don't want to request additional
1861 * RRs for stuff we didn't really ask for, and
1862 * also to avoid request loops, where
1863 * additional RRs from one transaction result
1864 * in another transaction whose additonal RRs
1865 * point back to the original transaction, and
1867 r
= dns_name_endswith(dns_resource_key_name(t
->key
), rr
->rrsig
.signer
);
1873 dnskey
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DNSKEY
, rr
->rrsig
.signer
);
1877 log_debug("Requesting DNSKEY to validate transaction %" PRIu16
" (%s, RRSIG with key tag: %" PRIu16
").",
1878 t
->id
, dns_resource_key_name(rr
->key
), rr
->rrsig
.key_tag
);
1879 r
= dns_transaction_request_dnssec_rr(t
, dnskey
);
1885 case DNS_TYPE_DNSKEY
: {
1886 /* For each DNSKEY we request the matching DS */
1887 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1889 /* If the DNSKEY we are looking at is not for
1890 * zone we are interested in, nor any of its
1891 * parents, we aren't interested, and don't
1892 * request it. After all, we don't want to end
1893 * up in request loops, and want to keep
1894 * additional traffic down. */
1896 r
= dns_name_endswith(dns_resource_key_name(t
->key
), dns_resource_key_name(rr
->key
));
1902 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
1906 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, DNSKEY with key tag: %" PRIu16
").",
1907 t
->id
, dns_resource_key_name(rr
->key
), dnssec_keytag(rr
, false));
1908 r
= dns_transaction_request_dnssec_rr(t
, ds
);
1917 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1919 /* For an unsigned SOA or NS, try to acquire
1920 * the matching DS RR, as we are at a zone cut
1921 * then, and whether a DS exists tells us
1922 * whether the zone is signed. Do so only if
1923 * this RR matches our original question,
1926 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1932 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
1938 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
1942 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned SOA/NS RRset).",
1943 t
->id
, dns_resource_key_name(rr
->key
));
1944 r
= dns_transaction_request_dnssec_rr(t
, ds
);
1952 case DNS_TYPE_CNAME
:
1953 case DNS_TYPE_DNAME
: {
1954 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
1957 /* CNAMEs and DNAMEs cannot be located at a
1958 * zone apex, hence ask for the parent SOA for
1959 * unsigned CNAME/DNAME RRs, maybe that's the
1960 * apex. But do all that only if this is
1961 * actually a response to our original
1964 * Similar for DS RRs, which are signed when
1965 * the parent SOA is signed. */
1967 r
= dns_transaction_is_primary_response(t
, rr
);
1973 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
1979 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
1985 name
= dns_resource_key_name(rr
->key
);
1986 r
= dns_name_parent(&name
);
1992 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, name
);
1996 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned CNAME/DNAME/DS RRset).",
1997 t
->id
, dns_resource_key_name(rr
->key
));
1998 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2006 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2008 /* For other unsigned RRsets (including
2009 * NSEC/NSEC3!), look for proof the zone is
2010 * unsigned, by requesting the SOA RR of the
2011 * zone. However, do so only if they are
2012 * directly relevant to our original
2015 r
= dns_transaction_is_primary_response(t
, rr
);
2021 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2027 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, dns_resource_key_name(rr
->key
));
2031 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned non-SOA/NS RRset <%s>).",
2032 t
->id
, dns_resource_key_name(rr
->key
), dns_resource_record_to_string(rr
));
2033 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2040 /* Above, we requested everything necessary to validate what
2041 * we got. Now, let's request what we need to validate what we
2044 r
= dns_transaction_has_unsigned_negative_answer(t
);
2051 name
= dns_resource_key_name(t
->key
);
2053 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2054 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2055 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2056 * though they have further children. If this was a DS request, then it's signed when the parent zone
2057 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2058 * to see if that is signed. */
2060 if (t
->key
->type
== DNS_TYPE_DS
) {
2061 r
= dns_name_parent(&name
);
2063 type
= DNS_TYPE_SOA
;
2064 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned empty DS response).",
2065 t
->id
, dns_resource_key_name(t
->key
));
2069 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
)) {
2072 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned empty SOA/NS response).",
2073 t
->id
, dns_resource_key_name(t
->key
));
2076 type
= DNS_TYPE_SOA
;
2077 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned empty non-SOA/NS/DS response).",
2078 t
->id
, dns_resource_key_name(t
->key
));
2082 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2084 soa
= dns_resource_key_new(t
->key
->class, type
, name
);
2088 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2094 return dns_transaction_dnssec_is_live(t
);
2097 void dns_transaction_notify(DnsTransaction
*t
, DnsTransaction
*source
) {
2101 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2102 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2103 the state is VALIDATING however, we should check if we are complete now. */
2105 if (t
->state
== DNS_TRANSACTION_VALIDATING
)
2106 dns_transaction_process_dnssec(t
);
2109 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction
*t
) {
2110 DnsResourceRecord
*rr
;
2115 /* Add all DNSKEY RRs from the answer that are validated by DS
2116 * RRs from the list of validated keys to the list of
2117 * validated keys. */
2119 DNS_ANSWER_FOREACH_IFINDEX(rr
, ifindex
, t
->answer
) {
2121 r
= dnssec_verify_dnskey_by_ds_search(rr
, t
->validated_keys
);
2127 /* If so, the DNSKEY is validated too. */
2128 r
= dns_answer_add_extend(&t
->validated_keys
, rr
, ifindex
, DNS_ANSWER_AUTHENTICATED
);
2136 static int dns_transaction_requires_rrsig(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2142 /* Checks if the RR we are looking for must be signed with an
2143 * RRSIG. This is used for positive responses. */
2145 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2148 if (dns_type_is_pseudo(rr
->key
->type
))
2151 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2157 switch (rr
->key
->type
) {
2159 case DNS_TYPE_RRSIG
:
2160 /* RRSIGs are the signatures themselves, they need no signing. */
2168 /* For SOA or NS RRs we look for a matching DS transaction */
2170 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2172 if (dt
->key
->class != rr
->key
->class)
2174 if (dt
->key
->type
!= DNS_TYPE_DS
)
2177 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2183 /* We found a DS transactions for the SOA/NS
2184 * RRs we are looking at. If it discovered signed DS
2185 * RRs, then we need to be signed, too. */
2187 if (!dt
->answer_authenticated
)
2190 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2193 /* We found nothing that proves this is safe to leave
2194 * this unauthenticated, hence ask inist on
2195 * authentication. */
2200 case DNS_TYPE_CNAME
:
2201 case DNS_TYPE_DNAME
: {
2202 const char *parent
= NULL
;
2207 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2209 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2212 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2214 if (dt
->key
->class != rr
->key
->class)
2216 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2220 parent
= dns_resource_key_name(rr
->key
);
2221 r
= dns_name_parent(&parent
);
2225 if (rr
->key
->type
== DNS_TYPE_DS
)
2228 /* A CNAME/DNAME without a parent? That's sooo weird. */
2229 log_debug("Transaction %" PRIu16
" claims CNAME/DNAME at root. Refusing.", t
->id
);
2234 r
= dns_name_equal(dns_resource_key_name(dt
->key
), parent
);
2240 return t
->answer_authenticated
;
2250 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2252 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2254 if (dt
->key
->class != rr
->key
->class)
2256 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2259 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2265 /* We found the transaction that was supposed to find
2266 * the SOA RR for us. It was successful, but found no
2267 * RR for us. This means we are not at a zone cut. In
2268 * this case, we require authentication if the SOA
2269 * lookup was authenticated too. */
2270 return t
->answer_authenticated
;
2277 static int dns_transaction_in_private_tld(DnsTransaction
*t
, const DnsResourceKey
*key
) {
2283 /* If DNSSEC downgrade mode is on, checks whether the
2284 * specified RR is one level below a TLD we have proven not to
2285 * exist. In such a case we assume that this is a private
2286 * domain, and permit it.
2288 * This detects cases like the Fritz!Box router networks. Each
2289 * Fritz!Box router serves a private "fritz.box" zone, in the
2290 * non-existing TLD "box". Requests for the "fritz.box" domain
2291 * are served by the router itself, while requests for the
2292 * "box" domain will result in NXDOMAIN.
2294 * Note that this logic is unable to detect cases where a
2295 * router serves a private DNS zone directly under
2296 * non-existing TLD. In such a case we cannot detect whether
2297 * the TLD is supposed to exist or not, as all requests we
2298 * make for it will be answered by the router's zone, and not
2299 * by the root zone. */
2303 if (t
->scope
->dnssec_mode
!= DNSSEC_ALLOW_DOWNGRADE
)
2304 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2306 tld
= dns_resource_key_name(key
);
2307 r
= dns_name_parent(&tld
);
2311 return false; /* Already the root domain */
2313 if (!dns_name_is_single_label(tld
))
2316 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2318 if (dt
->key
->class != key
->class)
2321 r
= dns_name_equal(dns_resource_key_name(dt
->key
), tld
);
2327 /* We found an auxiliary lookup we did for the TLD. If
2328 * that returned with NXDOMAIN, we know the TLD didn't
2329 * exist, and hence this might be a private zone. */
2331 return dt
->answer_rcode
== DNS_RCODE_NXDOMAIN
;
2337 static int dns_transaction_requires_nsec(DnsTransaction
*t
) {
2338 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2347 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2348 * this negative reply */
2350 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2353 if (dns_type_is_pseudo(t
->key
->type
))
2356 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
2362 r
= dns_transaction_in_private_tld(t
, t
->key
);
2366 /* The lookup is from a TLD that is proven not to
2367 * exist, and we are in downgrade mode, hence ignore
2368 * that fact that we didn't get any NSEC RRs.*/
2370 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2371 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2375 name
= dns_resource_key_name(t
->key
);
2377 if (t
->key
->type
== DNS_TYPE_DS
) {
2379 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2380 * hence check the parent SOA in this case. */
2382 r
= dns_name_parent(&name
);
2388 type
= DNS_TYPE_SOA
;
2390 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
))
2391 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2394 /* For all other negative replies, check for the SOA lookup */
2395 type
= DNS_TYPE_SOA
;
2397 /* For all other RRs we check the SOA on the same level to see
2398 * if it's signed. */
2400 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2402 if (dt
->key
->class != t
->key
->class)
2404 if (dt
->key
->type
!= type
)
2407 r
= dns_name_equal(dns_resource_key_name(dt
->key
), name
);
2413 return dt
->answer_authenticated
;
2416 /* If in doubt, require NSEC/NSEC3 */
2420 static int dns_transaction_dnskey_authenticated(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2421 DnsResourceRecord
*rrsig
;
2425 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2426 * the specified RRset is authenticated (i.e. has a matching
2429 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2435 DNS_ANSWER_FOREACH(rrsig
, t
->answer
) {
2439 r
= dnssec_key_match_rrsig(rr
->key
, rrsig
);
2445 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2447 if (dt
->key
->class != rr
->key
->class)
2450 if (dt
->key
->type
== DNS_TYPE_DNSKEY
) {
2452 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2458 /* OK, we found an auxiliary DNSKEY
2459 * lookup. If that lookup is
2460 * authenticated, report this. */
2462 if (dt
->answer_authenticated
)
2467 } else if (dt
->key
->type
== DNS_TYPE_DS
) {
2469 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2475 /* OK, we found an auxiliary DS
2476 * lookup. If that lookup is
2477 * authenticated and non-zero, we
2480 if (!dt
->answer_authenticated
)
2483 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2488 return found
? false : -ENXIO
;
2491 static int dns_transaction_known_signed(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2495 /* We know that the root domain is signed, hence if it appears
2496 * not to be signed, there's a problem with the DNS server */
2498 return rr
->key
->class == DNS_CLASS_IN
&&
2499 dns_name_is_root(dns_resource_key_name(rr
->key
));
2502 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction
*t
) {
2503 DnsResourceRecord
*rr
;
2508 /* Maybe warn the user that we encountered a revoked DNSKEY
2509 * for a key from our trust anchor. Note that we don't care
2510 * whether the DNSKEY can be authenticated or not. It's
2511 * sufficient if it is self-signed. */
2513 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2514 r
= dns_trust_anchor_check_revoked(&t
->scope
->manager
->trust_anchor
, rr
, t
->answer
);
2522 static int dns_transaction_invalidate_revoked_keys(DnsTransaction
*t
) {
2528 /* Removes all DNSKEY/DS objects from t->validated_keys that
2529 * our trust anchors database considers revoked. */
2532 DnsResourceRecord
*rr
;
2536 DNS_ANSWER_FOREACH(rr
, t
->validated_keys
) {
2537 r
= dns_trust_anchor_is_revoked(&t
->scope
->manager
->trust_anchor
, rr
);
2541 r
= dns_answer_remove_by_rr(&t
->validated_keys
, rr
);
2555 static int dns_transaction_copy_validated(DnsTransaction
*t
) {
2562 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
2564 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2566 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
2569 if (!dt
->answer_authenticated
)
2572 r
= dns_answer_extend(&t
->validated_keys
, dt
->answer
);
2581 DNSSEC_PHASE_DNSKEY
, /* Phase #1, only validate DNSKEYs */
2582 DNSSEC_PHASE_NSEC
, /* Phase #2, only validate NSEC+NSEC3 */
2583 DNSSEC_PHASE_ALL
, /* Phase #3, validate everything else */
2586 static int dnssec_validate_records(
2590 DnsAnswer
**validated
) {
2592 DnsResourceRecord
*rr
;
2595 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
2597 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2598 DnsResourceRecord
*rrsig
= NULL
;
2599 DnssecResult result
;
2601 switch (rr
->key
->type
) {
2602 case DNS_TYPE_RRSIG
:
2605 case DNS_TYPE_DNSKEY
:
2606 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
2607 if (phase
== DNSSEC_PHASE_NSEC
)
2612 case DNS_TYPE_NSEC3
:
2615 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
2616 if (phase
== DNSSEC_PHASE_DNSKEY
)
2621 /* We validate all other RRs only in the ALL phases */
2622 if (phase
!= DNSSEC_PHASE_ALL
)
2626 r
= dnssec_verify_rrset_search(t
->answer
, rr
->key
, t
->validated_keys
, USEC_INFINITY
, &result
, &rrsig
);
2630 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr
)), dnssec_result_to_string(result
));
2632 if (result
== DNSSEC_VALIDATED
) {
2634 if (rr
->key
->type
== DNS_TYPE_DNSKEY
) {
2635 /* If we just validated a DNSKEY RRset, then let's add these keys to
2636 * the set of validated keys for this transaction. */
2638 r
= dns_answer_copy_by_key(&t
->validated_keys
, t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
);
2642 /* Some of the DNSKEYs we just added might already have been revoked,
2643 * remove them again in that case. */
2644 r
= dns_transaction_invalidate_revoked_keys(t
);
2649 /* Add the validated RRset to the new list of validated
2650 * RRsets, and remove it from the unvalidated RRsets.
2651 * We mark the RRset as authenticated and cacheable. */
2652 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
);
2656 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_SECURE
, rr
->key
);
2658 /* Exit the loop, we dropped something from the answer, start from the beginning */
2662 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
2663 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
2664 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
2665 if (phase
!= DNSSEC_PHASE_ALL
)
2668 if (result
== DNSSEC_VALIDATED_WILDCARD
) {
2669 bool authenticated
= false;
2672 /* This RRset validated, but as a wildcard. This means we need
2673 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists.*/
2675 /* First step, determine the source of synthesis */
2676 r
= dns_resource_record_source(rrsig
, &source
);
2680 r
= dnssec_test_positive_wildcard(*validated
,
2681 dns_resource_key_name(rr
->key
),
2683 rrsig
->rrsig
.signer
,
2686 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
2688 result
= DNSSEC_INVALID
;
2690 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
,
2691 authenticated
? (DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
) : 0);
2695 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, rr
->key
);
2697 /* Exit the loop, we dropped something from the answer, start from the beginning */
2702 if (result
== DNSSEC_NO_SIGNATURE
) {
2703 r
= dns_transaction_requires_rrsig(t
, rr
);
2707 /* Data does not require signing. In that case, just copy it over,
2708 * but remember that this is by no means authenticated.*/
2709 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2713 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2717 r
= dns_transaction_known_signed(t
, rr
);
2721 /* This is an RR we know has to be signed. If it isn't this means
2722 * the server is not attaching RRSIGs, hence complain. */
2724 dns_server_packet_rrsig_missing(t
->server
, t
->current_feature_level
);
2726 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
2728 /* Downgrading is OK? If so, just consider the information unsigned */
2730 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2734 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2738 /* Otherwise, fail */
2739 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2743 r
= dns_transaction_in_private_tld(t
, rr
->key
);
2747 char s
[DNS_RESOURCE_KEY_STRING_MAX
];
2749 /* The data is from a TLD that is proven not to exist, and we are in downgrade
2750 * mode, hence ignore the fact that this was not signed. */
2752 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
2753 dns_resource_key_to_string(rr
->key
, s
, sizeof s
));
2755 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2759 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2766 DNSSEC_SIGNATURE_EXPIRED
,
2767 DNSSEC_UNSUPPORTED_ALGORITHM
)) {
2769 r
= dns_transaction_dnskey_authenticated(t
, rr
);
2770 if (r
< 0 && r
!= -ENXIO
)
2773 /* The DNSKEY transaction was not authenticated, this means there's
2774 * no DS for this, which means it's OK if no keys are found for this signature. */
2776 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2780 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2785 r
= dns_transaction_is_primary_response(t
, rr
);
2789 /* Look for a matching DNAME for this CNAME */
2790 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2794 /* Also look among the stuff we already validated */
2795 r
= dns_answer_has_dname_for_cname(*validated
, rr
);
2803 DNSSEC_SIGNATURE_EXPIRED
,
2804 DNSSEC_NO_SIGNATURE
))
2805 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, rr
->key
);
2806 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
2807 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, rr
->key
);
2809 /* This is a primary response to our question, and it failed validation.
2811 t
->answer_dnssec_result
= result
;
2815 /* This is a primary response, but we do have a DNAME RR
2816 * in the RR that can replay this CNAME, hence rely on
2817 * that, and we can remove the CNAME in favour of it. */
2820 /* This is just some auxiliary data. Just remove the RRset and continue. */
2821 r
= dns_answer_remove_by_key(&t
->answer
, rr
->key
);
2825 /* We dropped something from the answer, start from the beginning. */
2829 return 2; /* Finito. */
2832 int dns_transaction_validate_dnssec(DnsTransaction
*t
) {
2833 _cleanup_(dns_answer_unrefp
) DnsAnswer
*validated
= NULL
;
2835 DnsAnswerFlags flags
;
2837 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2841 /* We have now collected all DS and DNSKEY RRs in
2842 * t->validated_keys, let's see which RRs we can now
2843 * authenticate with that. */
2845 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2848 /* Already validated */
2849 if (t
->answer_dnssec_result
!= _DNSSEC_RESULT_INVALID
)
2852 /* Our own stuff needs no validation */
2853 if (IN_SET(t
->answer_source
, DNS_TRANSACTION_ZONE
, DNS_TRANSACTION_TRUST_ANCHOR
)) {
2854 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2855 t
->answer_authenticated
= true;
2859 /* Cached stuff is not affected by validation. */
2860 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
2863 if (!dns_transaction_dnssec_supported_full(t
)) {
2864 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
2865 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2866 log_debug("Not validating response for %" PRIu16
", server lacks DNSSEC support.", t
->id
);
2870 log_debug("Validating response from transaction %" PRIu16
" (%s).",
2872 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2874 /* First, see if this response contains any revoked trust
2875 * anchors we care about */
2876 r
= dns_transaction_check_revoked_trust_anchors(t
);
2880 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
2881 r
= dns_transaction_copy_validated(t
);
2885 /* Second, see if there are DNSKEYs we already know a
2886 * validated DS for. */
2887 r
= dns_transaction_validate_dnskey_by_ds(t
);
2891 /* Fourth, remove all DNSKEY and DS RRs again that our trust
2892 * anchor says are revoked. After all we might have marked
2893 * some keys revoked above, but they might still be lingering
2894 * in our validated_keys list. */
2895 r
= dns_transaction_invalidate_revoked_keys(t
);
2899 phase
= DNSSEC_PHASE_DNSKEY
;
2901 bool have_nsec
= false;
2903 r
= dnssec_validate_records(t
, phase
, &have_nsec
, &validated
);
2907 /* Try again as long as we managed to achieve something */
2911 if (phase
== DNSSEC_PHASE_DNSKEY
&& have_nsec
) {
2912 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
2913 phase
= DNSSEC_PHASE_NSEC
;
2917 if (phase
!= DNSSEC_PHASE_ALL
) {
2918 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
2919 * Note that in this third phase we start to remove RRs we couldn't validate. */
2920 phase
= DNSSEC_PHASE_ALL
;
2928 dns_answer_unref(t
->answer
);
2929 t
->answer
= validated
;
2932 /* At this point the answer only contains validated
2933 * RRsets. Now, let's see if it actually answers the question
2934 * we asked. If so, great! If it doesn't, then see if
2935 * NSEC/NSEC3 can prove this. */
2936 r
= dns_transaction_has_positive_answer(t
, &flags
);
2938 /* Yes, it answers the question! */
2940 if (flags
& DNS_ANSWER_AUTHENTICATED
) {
2941 /* The answer is fully authenticated, yay. */
2942 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2943 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
2944 t
->answer_authenticated
= true;
2946 /* The answer is not fully authenticated. */
2947 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
2948 t
->answer_authenticated
= false;
2951 } else if (r
== 0) {
2952 DnssecNsecResult nr
;
2953 bool authenticated
= false;
2955 /* Bummer! Let's check NSEC/NSEC3 */
2956 r
= dnssec_nsec_test(t
->answer
, t
->key
, &nr
, &authenticated
, &t
->answer_nsec_ttl
);
2962 case DNSSEC_NSEC_NXDOMAIN
:
2963 /* NSEC proves the domain doesn't exist. Very good. */
2964 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
2965 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2966 t
->answer_rcode
= DNS_RCODE_NXDOMAIN
;
2967 t
->answer_authenticated
= authenticated
;
2969 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
2972 case DNSSEC_NSEC_NODATA
:
2973 /* NSEC proves that there's no data here, very good. */
2974 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
2975 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2976 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
2977 t
->answer_authenticated
= authenticated
;
2979 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
2982 case DNSSEC_NSEC_OPTOUT
:
2983 /* NSEC3 says the data might not be signed */
2984 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
2985 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
2986 t
->answer_authenticated
= false;
2988 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
2991 case DNSSEC_NSEC_NO_RR
:
2992 /* No NSEC data? Bummer! */
2994 r
= dns_transaction_requires_nsec(t
);
2998 t
->answer_dnssec_result
= DNSSEC_NO_SIGNATURE
;
2999 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3001 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3002 t
->answer_authenticated
= false;
3003 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3008 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM
:
3009 /* We don't know the NSEC3 algorithm used? */
3010 t
->answer_dnssec_result
= DNSSEC_UNSUPPORTED_ALGORITHM
;
3011 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, t
->key
);
3014 case DNSSEC_NSEC_FOUND
:
3015 case DNSSEC_NSEC_CNAME
:
3016 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3017 t
->answer_dnssec_result
= DNSSEC_NSEC_MISMATCH
;
3018 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3022 assert_not_reached("Unexpected NSEC result.");
3029 static const char* const dns_transaction_state_table
[_DNS_TRANSACTION_STATE_MAX
] = {
3030 [DNS_TRANSACTION_NULL
] = "null",
3031 [DNS_TRANSACTION_PENDING
] = "pending",
3032 [DNS_TRANSACTION_VALIDATING
] = "validating",
3033 [DNS_TRANSACTION_RCODE_FAILURE
] = "rcode-failure",
3034 [DNS_TRANSACTION_SUCCESS
] = "success",
3035 [DNS_TRANSACTION_NO_SERVERS
] = "no-servers",
3036 [DNS_TRANSACTION_TIMEOUT
] = "timeout",
3037 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
] = "attempts-max-reached",
3038 [DNS_TRANSACTION_INVALID_REPLY
] = "invalid-reply",
3039 [DNS_TRANSACTION_ERRNO
] = "errno",
3040 [DNS_TRANSACTION_ABORTED
] = "aborted",
3041 [DNS_TRANSACTION_DNSSEC_FAILED
] = "dnssec-failed",
3042 [DNS_TRANSACTION_NO_TRUST_ANCHOR
] = "no-trust-anchor",
3043 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
] = "rr-type-unsupported",
3044 [DNS_TRANSACTION_NETWORK_DOWN
] = "network-down",
3045 [DNS_TRANSACTION_NOT_FOUND
] = "not-found",
3047 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state
, DnsTransactionState
);
3049 static const char* const dns_transaction_source_table
[_DNS_TRANSACTION_SOURCE_MAX
] = {
3050 [DNS_TRANSACTION_NETWORK
] = "network",
3051 [DNS_TRANSACTION_CACHE
] = "cache",
3052 [DNS_TRANSACTION_ZONE
] = "zone",
3053 [DNS_TRANSACTION_TRUST_ANCHOR
] = "trust-anchor",
3055 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source
, DnsTransactionSource
);