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 */
561 t
->stream
->ifindex
= t
->scope
->link
->ifindex
;
563 dns_transaction_reset_answer(t
);
565 t
->tried_stream
= true;
570 static void dns_transaction_cache_answer(DnsTransaction
*t
) {
573 /* For mDNS we cache whenever we get the packet, rather than
574 * in each transaction. */
575 if (!IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
))
578 /* We never cache if this packet is from the local host, under
579 * the assumption that a locally running DNS server would
580 * cache this anyway, and probably knows better when to flush
581 * the cache then we could. */
582 if (!DNS_PACKET_SHALL_CACHE(t
->received
))
585 dns_cache_put(&t
->scope
->cache
,
589 t
->answer_authenticated
,
593 &t
->received
->sender
);
596 static bool dns_transaction_dnssec_is_live(DnsTransaction
*t
) {
602 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
603 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
609 static int dns_transaction_dnssec_ready(DnsTransaction
*t
) {
615 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
616 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
618 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
622 case DNS_TRANSACTION_NULL
:
623 case DNS_TRANSACTION_PENDING
:
624 case DNS_TRANSACTION_VALIDATING
:
628 case DNS_TRANSACTION_RCODE_FAILURE
:
629 if (dt
->answer_rcode
!= DNS_RCODE_NXDOMAIN
) {
630 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt
->answer_rcode
));
634 /* Fall-through: NXDOMAIN is good enough for us. This is because some DNS servers erronously
635 * return NXDOMAIN for empty non-terminals (Akamai...), and we need to handle that nicely, when
636 * asking for parent SOA or similar RRs to make unsigned proofs. */
638 case DNS_TRANSACTION_SUCCESS
:
642 case DNS_TRANSACTION_DNSSEC_FAILED
:
643 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
644 * validationr result */
646 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt
->answer_dnssec_result
));
647 t
->answer_dnssec_result
= dt
->answer_dnssec_result
; /* Copy error code over */
648 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
653 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt
->state
));
658 /* All is ready, we can go and validate */
662 t
->answer_dnssec_result
= DNSSEC_FAILED_AUXILIARY
;
663 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
667 static void dns_transaction_process_dnssec(DnsTransaction
*t
) {
672 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
673 r
= dns_transaction_dnssec_ready(t
);
676 if (r
== 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
679 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
680 * restart the lookup immediately. */
681 r
= dns_transaction_maybe_restart(t
);
684 if (r
> 0) /* Transaction got restarted... */
687 /* All our auxiliary DNSSEC transactions are complete now. Try
688 * to validate our RRset now. */
689 r
= dns_transaction_validate_dnssec(t
);
691 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
697 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
&&
698 t
->scope
->dnssec_mode
== DNSSEC_YES
) {
699 /* We are not in automatic downgrade mode, and the
700 * server is bad, refuse operation. */
701 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
705 if (!IN_SET(t
->answer_dnssec_result
,
706 _DNSSEC_RESULT_INVALID
, /* No DNSSEC validation enabled */
707 DNSSEC_VALIDATED
, /* Answer is signed and validated successfully */
708 DNSSEC_UNSIGNED
, /* Answer is right-fully unsigned */
709 DNSSEC_INCOMPATIBLE_SERVER
)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
710 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
714 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
)
715 dns_server_warn_downgrade(t
->server
);
717 dns_transaction_cache_answer(t
);
719 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
720 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
722 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
727 t
->answer_errno
= -r
;
728 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
731 static int dns_transaction_has_positive_answer(DnsTransaction
*t
, DnsAnswerFlags
*flags
) {
736 /* Checks whether the answer is positive, i.e. either a direct
737 * answer to the question, or a CNAME/DNAME for it */
739 r
= dns_answer_match_key(t
->answer
, t
->key
, flags
);
743 r
= dns_answer_find_cname_or_dname(t
->answer
, t
->key
, NULL
, flags
);
750 static int dns_transaction_fix_rcode(DnsTransaction
*t
) {
755 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
756 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
757 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
758 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
759 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
760 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
761 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
762 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
763 * incomplete CNAME/DNAME chain.
765 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
766 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
769 if (t
->answer_rcode
!= DNS_RCODE_NXDOMAIN
)
772 r
= dns_transaction_has_positive_answer(t
, NULL
);
776 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
780 void dns_transaction_process_reply(DnsTransaction
*t
, DnsPacket
*p
) {
787 assert(t
->scope
->manager
);
789 if (t
->state
!= DNS_TRANSACTION_PENDING
)
792 /* Note that this call might invalidate the query. Callers
793 * should hence not attempt to access the query or transaction
794 * after calling this function. */
796 log_debug("Processing incoming packet on transaction %" PRIu16
".", t
->id
);
798 switch (t
->scope
->protocol
) {
800 case DNS_PROTOCOL_LLMNR
:
801 assert(t
->scope
->link
);
803 /* For LLMNR we will not accept any packets from other
806 if (p
->ifindex
!= t
->scope
->link
->ifindex
)
809 if (p
->family
!= t
->scope
->family
)
812 /* Tentative packets are not full responses but still
813 * useful for identifying uniqueness conflicts during
815 if (DNS_PACKET_LLMNR_T(p
)) {
816 dns_transaction_tentative(t
, p
);
822 case DNS_PROTOCOL_MDNS
:
823 assert(t
->scope
->link
);
825 /* For mDNS we will not accept any packets from other interfaces */
826 if (p
->ifindex
!= t
->scope
->link
->ifindex
)
829 if (p
->family
!= t
->scope
->family
)
834 case DNS_PROTOCOL_DNS
:
835 /* Note that we do not need to verify the
836 * addresses/port numbers of incoming traffic, as we
837 * invoked connect() on our UDP socket in which case
838 * the kernel already does the needed verification for
843 assert_not_reached("Invalid DNS protocol.");
846 if (t
->received
!= p
) {
847 dns_packet_unref(t
->received
);
848 t
->received
= dns_packet_ref(p
);
851 t
->answer_source
= DNS_TRANSACTION_NETWORK
;
853 if (p
->ipproto
== IPPROTO_TCP
) {
854 if (DNS_PACKET_TC(p
)) {
855 /* Truncated via TCP? Somebody must be fucking with us */
856 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
860 if (DNS_PACKET_ID(p
) != t
->id
) {
861 /* Not the reply to our query? Somebody must be fucking with us */
862 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
867 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
869 switch (t
->scope
->protocol
) {
871 case DNS_PROTOCOL_DNS
:
874 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_FORMERR
, DNS_RCODE_SERVFAIL
, DNS_RCODE_NOTIMP
)) {
876 /* Request failed, immediately try again with reduced features */
877 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
879 dns_server_packet_failed(t
->server
, t
->current_feature_level
);
880 dns_transaction_retry(t
);
882 } else if (DNS_PACKET_TC(p
))
883 dns_server_packet_truncated(t
->server
, t
->current_feature_level
);
887 case DNS_PROTOCOL_LLMNR
:
888 case DNS_PROTOCOL_MDNS
:
889 dns_scope_packet_received(t
->scope
, ts
- t
->start_usec
);
893 assert_not_reached("Invalid DNS protocol.");
896 if (DNS_PACKET_TC(p
)) {
898 /* Truncated packets for mDNS are not allowed. Give up immediately. */
899 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
) {
900 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
904 log_debug("Reply truncated, retrying via TCP.");
906 /* Response was truncated, let's try again with good old TCP */
907 r
= dns_transaction_open_tcp(t
);
909 /* No servers found? Damn! */
910 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
913 if (r
== -EOPNOTSUPP
) {
914 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
915 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
919 /* On LLMNR, if we cannot connect to the host,
920 * we immediately give up */
921 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
924 /* On DNS, couldn't send? Try immediately again, with a new server */
925 dns_transaction_retry(t
);
931 /* After the superficial checks, actually parse the message. */
932 r
= dns_packet_extract(p
);
934 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
938 /* Report that the OPT RR was missing */
941 dns_server_packet_bad_opt(t
->server
, t
->current_feature_level
);
943 dns_server_packet_received(t
->server
, p
->ipproto
, t
->current_feature_level
, ts
- t
->start_usec
, p
->size
);
946 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
947 r
= dns_transaction_maybe_restart(t
);
950 if (r
> 0) /* Transaction got restarted... */
953 if (IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
)) {
955 /* Only consider responses with equivalent query section to the request */
956 r
= dns_packet_is_reply_for(p
, t
->key
);
960 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
964 /* Install the answer as answer to the transaction */
965 dns_answer_unref(t
->answer
);
966 t
->answer
= dns_answer_ref(p
->answer
);
967 t
->answer_rcode
= DNS_PACKET_RCODE(p
);
968 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
969 t
->answer_authenticated
= false;
971 r
= dns_transaction_fix_rcode(t
);
975 /* Block GC while starting requests for additional DNSSEC RRs */
977 r
= dns_transaction_request_dnssec_keys(t
);
980 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
981 if (!dns_transaction_gc(t
))
984 /* Requesting additional keys might have resulted in
985 * this transaction to fail, since the auxiliary
986 * request failed for some reason. If so, we are not
987 * in pending state anymore, and we should exit
989 if (t
->state
!= DNS_TRANSACTION_PENDING
)
994 /* There are DNSSEC transactions pending now. Update the state accordingly. */
995 t
->state
= DNS_TRANSACTION_VALIDATING
;
996 dns_transaction_close_connection(t
);
997 dns_transaction_stop_timeout(t
);
1002 dns_transaction_process_dnssec(t
);
1006 t
->answer_errno
= -r
;
1007 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1010 static int on_dns_packet(sd_event_source
*s
, int fd
, uint32_t revents
, void *userdata
) {
1011 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1012 DnsTransaction
*t
= userdata
;
1018 r
= manager_recv(t
->scope
->manager
, fd
, DNS_PROTOCOL_DNS
, &p
);
1019 if (ERRNO_IS_DISCONNECT(-r
)) {
1022 /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next
1023 * recvmsg(). Treat this like a lost packet. */
1025 log_debug_errno(r
, "Connection failure for DNS UDP packet: %m");
1026 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
1027 dns_server_packet_lost(t
->server
, IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1029 dns_transaction_retry(t
);
1033 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1034 t
->answer_errno
= -r
;
1038 r
= dns_packet_validate_reply(p
);
1040 log_debug_errno(r
, "Received invalid DNS packet as response, ignoring: %m");
1044 log_debug("Received inappropriate DNS packet as response, ignoring.");
1048 if (DNS_PACKET_ID(p
) != t
->id
) {
1049 log_debug("Received packet with incorrect transaction ID, ignoring.");
1053 dns_transaction_process_reply(t
, p
);
1057 static int dns_transaction_emit_udp(DnsTransaction
*t
) {
1062 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1064 r
= dns_transaction_pick_server(t
);
1068 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_UDP
)
1071 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
1074 if (r
> 0 || t
->dns_udp_fd
< 0) { /* Server changed, or no connection yet. */
1077 dns_transaction_close_connection(t
);
1079 fd
= dns_scope_socket_udp(t
->scope
, t
->server
, 53);
1083 r
= sd_event_add_io(t
->scope
->manager
->event
, &t
->dns_udp_event_source
, fd
, EPOLLIN
, on_dns_packet
, t
);
1089 (void) sd_event_source_set_description(t
->dns_udp_event_source
, "dns-transaction-udp");
1093 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
1097 dns_transaction_close_connection(t
);
1099 r
= dns_scope_emit_udp(t
->scope
, t
->dns_udp_fd
, t
->sent
);
1103 dns_transaction_reset_answer(t
);
1108 static int on_transaction_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1109 DnsTransaction
*t
= userdata
;
1114 if (!t
->initial_jitter_scheduled
|| t
->initial_jitter_elapsed
) {
1115 /* Timeout reached? Increase the timeout for the server used */
1116 switch (t
->scope
->protocol
) {
1118 case DNS_PROTOCOL_DNS
:
1120 dns_server_packet_lost(t
->server
, t
->stream
? IPPROTO_TCP
: IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1123 case DNS_PROTOCOL_LLMNR
:
1124 case DNS_PROTOCOL_MDNS
:
1125 dns_scope_packet_lost(t
->scope
, usec
- t
->start_usec
);
1129 assert_not_reached("Invalid DNS protocol.");
1132 if (t
->initial_jitter_scheduled
)
1133 t
->initial_jitter_elapsed
= true;
1136 log_debug("Timeout reached on transaction %" PRIu16
".", t
->id
);
1138 dns_transaction_retry(t
);
1142 static usec_t
transaction_get_resend_timeout(DnsTransaction
*t
) {
1146 switch (t
->scope
->protocol
) {
1148 case DNS_PROTOCOL_DNS
:
1150 return t
->server
->resend_timeout
;
1152 case DNS_PROTOCOL_MDNS
:
1153 assert(t
->n_attempts
> 0);
1154 return (1 << (t
->n_attempts
- 1)) * USEC_PER_SEC
;
1156 case DNS_PROTOCOL_LLMNR
:
1157 return t
->scope
->resend_timeout
;
1160 assert_not_reached("Invalid DNS protocol.");
1164 static int dns_transaction_prepare(DnsTransaction
*t
, usec_t ts
) {
1169 dns_transaction_stop_timeout(t
);
1171 r
= dns_scope_network_good(t
->scope
);
1175 dns_transaction_complete(t
, DNS_TRANSACTION_NETWORK_DOWN
);
1179 if (t
->n_attempts
>= TRANSACTION_ATTEMPTS_MAX(t
->scope
->protocol
)) {
1180 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1184 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& t
->tried_stream
) {
1185 /* If we already tried via a stream, then we don't
1186 * retry on LLMNR. See RFC 4795, Section 2.7. */
1187 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1194 dns_transaction_reset_answer(t
);
1195 dns_transaction_flush_dnssec_transactions(t
);
1197 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1198 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1199 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, t
->key
, &t
->answer
);
1203 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1204 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1205 t
->answer_authenticated
= true;
1206 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1210 if (dns_name_is_root(dns_resource_key_name(t
->key
)) &&
1211 t
->key
->type
== DNS_TYPE_DS
) {
1213 /* Hmm, this is a request for the root DS? A
1214 * DS RR doesn't exist in the root zone, and
1215 * if our trust anchor didn't know it either,
1216 * this means we cannot do any DNSSEC logic
1219 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
1220 /* We are in downgrade mode. In this
1221 * case, synthesize an unsigned empty
1222 * response, so that the any lookup
1223 * depending on this one can continue
1224 * assuming there was no DS, and hence
1225 * the root zone was unsigned. */
1227 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1228 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1229 t
->answer_authenticated
= false;
1230 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1232 /* If we are not in downgrade mode,
1233 * then fail the lookup, because we
1234 * cannot reasonably answer it. There
1235 * might be DS RRs, but we don't know
1236 * them, and the DNS server won't tell
1237 * them to us (and even if it would,
1238 * we couldn't validate and trust them. */
1239 dns_transaction_complete(t
, DNS_TRANSACTION_NO_TRUST_ANCHOR
);
1245 /* Check the zone, but only if this transaction is not used
1246 * for probing or verifying a zone item. */
1247 if (set_isempty(t
->notify_zone_items
)) {
1249 r
= dns_zone_lookup(&t
->scope
->zone
, t
->key
, &t
->answer
, NULL
, NULL
);
1253 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1254 t
->answer_source
= DNS_TRANSACTION_ZONE
;
1255 t
->answer_authenticated
= true;
1256 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1261 /* Check the cache, but only if this transaction is not used
1262 * for probing or verifying a zone item. */
1263 if (set_isempty(t
->notify_zone_items
)) {
1265 /* Before trying the cache, let's make sure we figured out a
1266 * server to use. Should this cause a change of server this
1267 * might flush the cache. */
1268 dns_scope_get_dns_server(t
->scope
);
1270 /* Let's then prune all outdated entries */
1271 dns_cache_prune(&t
->scope
->cache
);
1273 r
= dns_cache_lookup(&t
->scope
->cache
, t
->key
, &t
->answer_rcode
, &t
->answer
, &t
->answer_authenticated
);
1277 t
->answer_source
= DNS_TRANSACTION_CACHE
;
1278 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
1279 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1281 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
1289 static int dns_transaction_make_packet_mdns(DnsTransaction
*t
) {
1291 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1292 bool add_known_answers
= false;
1293 DnsTransaction
*other
;
1299 assert(t
->scope
->protocol
== DNS_PROTOCOL_MDNS
);
1301 /* Discard any previously prepared packet, so we can start over and coalesce again */
1302 t
->sent
= dns_packet_unref(t
->sent
);
1304 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, false);
1308 r
= dns_packet_append_key(p
, t
->key
, NULL
);
1314 if (dns_key_is_shared(t
->key
))
1315 add_known_answers
= true;
1318 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1319 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1320 * in our current scope, and see whether their timing contraints allow them to be sent.
1323 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1325 LIST_FOREACH(transactions_by_scope
, other
, t
->scope
->transactions
) {
1327 /* Skip ourselves */
1331 if (other
->state
!= DNS_TRANSACTION_PENDING
)
1334 if (other
->next_attempt_after
> ts
)
1337 if (qdcount
>= UINT16_MAX
)
1340 r
= dns_packet_append_key(p
, other
->key
, NULL
);
1343 * If we can't stuff more questions into the packet, just give up.
1344 * One of the 'other' transactions will fire later and take care of the rest.
1352 r
= dns_transaction_prepare(other
, ts
);
1356 ts
+= transaction_get_resend_timeout(other
);
1358 r
= sd_event_add_time(
1359 other
->scope
->manager
->event
,
1360 &other
->timeout_event_source
,
1361 clock_boottime_or_monotonic(),
1363 on_transaction_timeout
, other
);
1367 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1369 other
->state
= DNS_TRANSACTION_PENDING
;
1370 other
->next_attempt_after
= ts
;
1374 if (dns_key_is_shared(other
->key
))
1375 add_known_answers
= true;
1378 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(qdcount
);
1380 /* Append known answer section if we're asking for any shared record */
1381 if (add_known_answers
) {
1382 r
= dns_cache_export_shared_to_packet(&t
->scope
->cache
, p
);
1393 static int dns_transaction_make_packet(DnsTransaction
*t
) {
1394 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1399 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)
1400 return dns_transaction_make_packet_mdns(t
);
1405 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, t
->scope
->dnssec_mode
!= DNSSEC_NO
);
1409 r
= dns_packet_append_key(p
, t
->key
, NULL
);
1413 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
1414 DNS_PACKET_HEADER(p
)->id
= t
->id
;
1422 int dns_transaction_go(DnsTransaction
*t
) {
1425 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1429 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1431 r
= dns_transaction_prepare(t
, ts
);
1435 log_debug("Transaction %" PRIu16
" for <%s> scope %s on %s/%s.",
1437 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
1438 dns_protocol_to_string(t
->scope
->protocol
),
1439 t
->scope
->link
? t
->scope
->link
->name
: "*",
1440 af_to_name_short(t
->scope
->family
));
1442 if (!t
->initial_jitter_scheduled
&&
1443 (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
||
1444 t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)) {
1445 usec_t jitter
, accuracy
;
1447 /* RFC 4795 Section 2.7 suggests all queries should be
1448 * delayed by a random time from 0 to JITTER_INTERVAL. */
1450 t
->initial_jitter_scheduled
= true;
1452 random_bytes(&jitter
, sizeof(jitter
));
1454 switch (t
->scope
->protocol
) {
1456 case DNS_PROTOCOL_LLMNR
:
1457 jitter
%= LLMNR_JITTER_INTERVAL_USEC
;
1458 accuracy
= LLMNR_JITTER_INTERVAL_USEC
;
1461 case DNS_PROTOCOL_MDNS
:
1462 jitter
%= MDNS_JITTER_RANGE_USEC
;
1463 jitter
+= MDNS_JITTER_MIN_USEC
;
1464 accuracy
= MDNS_JITTER_RANGE_USEC
;
1467 assert_not_reached("bad protocol");
1470 r
= sd_event_add_time(
1471 t
->scope
->manager
->event
,
1472 &t
->timeout_event_source
,
1473 clock_boottime_or_monotonic(),
1474 ts
+ jitter
, accuracy
,
1475 on_transaction_timeout
, t
);
1479 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1482 t
->next_attempt_after
= ts
;
1483 t
->state
= DNS_TRANSACTION_PENDING
;
1485 log_debug("Delaying %s transaction for " USEC_FMT
"us.", dns_protocol_to_string(t
->scope
->protocol
), jitter
);
1489 /* Otherwise, we need to ask the network */
1490 r
= dns_transaction_make_packet(t
);
1494 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&&
1495 (dns_name_endswith(dns_resource_key_name(t
->key
), "in-addr.arpa") > 0 ||
1496 dns_name_endswith(dns_resource_key_name(t
->key
), "ip6.arpa") > 0)) {
1498 /* RFC 4795, Section 2.4. says reverse lookups shall
1499 * always be made via TCP on LLMNR */
1500 r
= dns_transaction_open_tcp(t
);
1502 /* Try via UDP, and if that fails due to large size or lack of
1503 * support try via TCP */
1504 r
= dns_transaction_emit_udp(t
);
1506 log_debug("Sending query via TCP since it is too large.");
1508 log_debug("Sending query via TCP since server doesn't support UDP.");
1509 if (r
== -EMSGSIZE
|| r
== -EAGAIN
)
1510 r
= dns_transaction_open_tcp(t
);
1514 /* No servers to send this to? */
1515 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
1518 if (r
== -EOPNOTSUPP
) {
1519 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1520 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
1523 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& ERRNO_IS_DISCONNECT(-r
)) {
1524 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
1525 * answer this request with this protocol. */
1526 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
1530 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1533 /* Couldn't send? Try immediately again, with a new server */
1534 dns_scope_next_dns_server(t
->scope
);
1536 return dns_transaction_go(t
);
1539 ts
+= transaction_get_resend_timeout(t
);
1541 r
= sd_event_add_time(
1542 t
->scope
->manager
->event
,
1543 &t
->timeout_event_source
,
1544 clock_boottime_or_monotonic(),
1546 on_transaction_timeout
, t
);
1550 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1552 t
->state
= DNS_TRANSACTION_PENDING
;
1553 t
->next_attempt_after
= ts
;
1558 static int dns_transaction_find_cyclic(DnsTransaction
*t
, DnsTransaction
*aux
) {
1566 /* Try to find cyclic dependencies between transaction objects */
1571 SET_FOREACH(n
, aux
->dnssec_transactions
, i
) {
1572 r
= dns_transaction_find_cyclic(t
, n
);
1580 static int dns_transaction_add_dnssec_transaction(DnsTransaction
*t
, DnsResourceKey
*key
, DnsTransaction
**ret
) {
1581 DnsTransaction
*aux
;
1588 aux
= dns_scope_find_transaction(t
->scope
, key
, true);
1590 r
= dns_transaction_new(&aux
, t
->scope
, key
);
1594 if (set_contains(t
->dnssec_transactions
, aux
)) {
1599 r
= dns_transaction_find_cyclic(t
, aux
);
1603 char s
[DNS_RESOURCE_KEY_STRING_MAX
], saux
[DNS_RESOURCE_KEY_STRING_MAX
];
1605 log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16
" (%s) as dependency for %" PRIu16
" (%s).",
1607 dns_resource_key_to_string(t
->key
, s
, sizeof s
),
1609 dns_resource_key_to_string(aux
->key
, saux
, sizeof saux
));
1615 r
= set_ensure_allocated(&t
->dnssec_transactions
, NULL
);
1619 r
= set_ensure_allocated(&aux
->notify_transactions
, NULL
);
1623 r
= set_ensure_allocated(&aux
->notify_transactions_done
, NULL
);
1627 r
= set_put(t
->dnssec_transactions
, aux
);
1631 r
= set_put(aux
->notify_transactions
, t
);
1633 (void) set_remove(t
->dnssec_transactions
, aux
);
1641 dns_transaction_gc(aux
);
1645 static int dns_transaction_request_dnssec_rr(DnsTransaction
*t
, DnsResourceKey
*key
) {
1646 _cleanup_(dns_answer_unrefp
) DnsAnswer
*a
= NULL
;
1647 DnsTransaction
*aux
;
1653 /* Try to get the data from the trust anchor */
1654 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, key
, &a
);
1658 r
= dns_answer_extend(&t
->validated_keys
, a
);
1665 /* This didn't work, ask for it via the network/cache then. */
1666 r
= dns_transaction_add_dnssec_transaction(t
, key
, &aux
);
1667 if (r
== -ELOOP
) /* This would result in a cyclic dependency */
1672 if (aux
->state
== DNS_TRANSACTION_NULL
) {
1673 r
= dns_transaction_go(aux
);
1681 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction
*t
, const char *name
) {
1686 /* Check whether the specified name is in the NTA
1687 * database, either in the global one, or the link-local
1690 r
= dns_trust_anchor_lookup_negative(&t
->scope
->manager
->trust_anchor
, name
);
1694 if (!t
->scope
->link
)
1697 return set_contains(t
->scope
->link
->dnssec_negative_trust_anchors
, name
);
1700 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction
*t
) {
1705 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
1706 * RRs to prove it */
1708 r
= dns_transaction_has_positive_answer(t
, NULL
);
1714 /* Is this key explicitly listed as a negative trust anchor?
1715 * If so, it's nothing we need to care about */
1716 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
1722 /* The answer does not contain any RRs that match to the
1723 * question. If so, let's see if there are any NSEC/NSEC3 RRs
1724 * included. If not, the answer is unsigned. */
1726 r
= dns_answer_contains_nsec_or_nsec3(t
->answer
);
1735 static int dns_transaction_is_primary_response(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
1741 /* Check if the specified RR is the "primary" response,
1742 * i.e. either matches the question precisely or is a
1743 * CNAME/DNAME for it. */
1745 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1749 return dns_resource_key_match_cname_or_dname(t
->key
, rr
->key
, NULL
);
1752 static bool dns_transaction_dnssec_supported(DnsTransaction
*t
) {
1755 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
1756 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
1758 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1761 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
1762 * be supported, hence return true. */
1766 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_DO
)
1769 return dns_server_dnssec_supported(t
->server
);
1772 static bool dns_transaction_dnssec_supported_full(DnsTransaction
*t
) {
1778 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
1780 if (!dns_transaction_dnssec_supported(t
))
1783 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
1784 if (!dns_transaction_dnssec_supported(dt
))
1790 int dns_transaction_request_dnssec_keys(DnsTransaction
*t
) {
1791 DnsResourceRecord
*rr
;
1798 * Retrieve all auxiliary RRs for the answer we got, so that
1799 * we can verify signatures or prove that RRs are rightfully
1800 * unsigned. Specifically:
1802 * - For RRSIG we get the matching DNSKEY
1803 * - For DNSKEY we get the matching DS
1804 * - For unsigned SOA/NS we get the matching DS
1805 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
1806 * - For other unsigned RRs we get the matching SOA RR
1807 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
1808 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
1809 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
1812 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
1814 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
1815 return 0; /* We only need to validate stuff from the network */
1816 if (!dns_transaction_dnssec_supported(t
))
1817 return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */
1819 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
1821 if (dns_type_is_pseudo(rr
->key
->type
))
1824 /* If this RR is in the negative trust anchor, we don't need to validate it. */
1825 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
1831 switch (rr
->key
->type
) {
1833 case DNS_TYPE_RRSIG
: {
1834 /* For each RRSIG we request the matching DNSKEY */
1835 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*dnskey
= NULL
;
1837 /* If this RRSIG is about a DNSKEY RR and the
1838 * signer is the same as the owner, then we
1839 * already have the DNSKEY, and we don't have
1840 * to look for more. */
1841 if (rr
->rrsig
.type_covered
== DNS_TYPE_DNSKEY
) {
1842 r
= dns_name_equal(rr
->rrsig
.signer
, dns_resource_key_name(rr
->key
));
1849 /* If the signer is not a parent of our
1850 * original query, then this is about an
1851 * auxiliary RRset, but not anything we asked
1852 * for. In this case we aren't interested,
1853 * because we don't want to request additional
1854 * RRs for stuff we didn't really ask for, and
1855 * also to avoid request loops, where
1856 * additional RRs from one transaction result
1857 * in another transaction whose additonal RRs
1858 * point back to the original transaction, and
1860 r
= dns_name_endswith(dns_resource_key_name(t
->key
), rr
->rrsig
.signer
);
1866 dnskey
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DNSKEY
, rr
->rrsig
.signer
);
1870 log_debug("Requesting DNSKEY to validate transaction %" PRIu16
" (%s, RRSIG with key tag: %" PRIu16
").",
1871 t
->id
, dns_resource_key_name(rr
->key
), rr
->rrsig
.key_tag
);
1872 r
= dns_transaction_request_dnssec_rr(t
, dnskey
);
1878 case DNS_TYPE_DNSKEY
: {
1879 /* For each DNSKEY we request the matching DS */
1880 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1882 /* If the DNSKEY we are looking at is not for
1883 * zone we are interested in, nor any of its
1884 * parents, we aren't interested, and don't
1885 * request it. After all, we don't want to end
1886 * up in request loops, and want to keep
1887 * additional traffic down. */
1889 r
= dns_name_endswith(dns_resource_key_name(t
->key
), dns_resource_key_name(rr
->key
));
1895 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
1899 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, DNSKEY with key tag: %" PRIu16
").",
1900 t
->id
, dns_resource_key_name(rr
->key
), dnssec_keytag(rr
, false));
1901 r
= dns_transaction_request_dnssec_rr(t
, ds
);
1910 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
1912 /* For an unsigned SOA or NS, try to acquire
1913 * the matching DS RR, as we are at a zone cut
1914 * then, and whether a DS exists tells us
1915 * whether the zone is signed. Do so only if
1916 * this RR matches our original question,
1919 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1925 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
1931 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
1935 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned SOA/NS RRset).",
1936 t
->id
, dns_resource_key_name(rr
->key
));
1937 r
= dns_transaction_request_dnssec_rr(t
, ds
);
1945 case DNS_TYPE_CNAME
:
1946 case DNS_TYPE_DNAME
: {
1947 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
1950 /* CNAMEs and DNAMEs cannot be located at a
1951 * zone apex, hence ask for the parent SOA for
1952 * unsigned CNAME/DNAME RRs, maybe that's the
1953 * apex. But do all that only if this is
1954 * actually a response to our original
1957 * Similar for DS RRs, which are signed when
1958 * the parent SOA is signed. */
1960 r
= dns_transaction_is_primary_response(t
, rr
);
1966 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
1972 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
1978 name
= dns_resource_key_name(rr
->key
);
1979 r
= dns_name_parent(&name
);
1985 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, name
);
1989 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned CNAME/DNAME/DS RRset).",
1990 t
->id
, dns_resource_key_name(rr
->key
));
1991 r
= dns_transaction_request_dnssec_rr(t
, soa
);
1999 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2001 /* For other unsigned RRsets (including
2002 * NSEC/NSEC3!), look for proof the zone is
2003 * unsigned, by requesting the SOA RR of the
2004 * zone. However, do so only if they are
2005 * directly relevant to our original
2008 r
= dns_transaction_is_primary_response(t
, rr
);
2014 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2020 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, dns_resource_key_name(rr
->key
));
2024 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned non-SOA/NS RRset <%s>).",
2025 t
->id
, dns_resource_key_name(rr
->key
), dns_resource_record_to_string(rr
));
2026 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2033 /* Above, we requested everything necessary to validate what
2034 * we got. Now, let's request what we need to validate what we
2037 r
= dns_transaction_has_unsigned_negative_answer(t
);
2044 name
= dns_resource_key_name(t
->key
);
2046 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2047 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2048 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2049 * though they have further children. If this was a DS request, then it's signed when the parent zone
2050 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2051 * to see if that is signed. */
2053 if (t
->key
->type
== DNS_TYPE_DS
) {
2054 r
= dns_name_parent(&name
);
2056 type
= DNS_TYPE_SOA
;
2057 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned empty DS response).",
2058 t
->id
, dns_resource_key_name(t
->key
));
2062 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
)) {
2065 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned empty SOA/NS response).",
2066 t
->id
, dns_resource_key_name(t
->key
));
2069 type
= DNS_TYPE_SOA
;
2070 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned empty non-SOA/NS/DS response).",
2071 t
->id
, dns_resource_key_name(t
->key
));
2075 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2077 soa
= dns_resource_key_new(t
->key
->class, type
, name
);
2081 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2087 return dns_transaction_dnssec_is_live(t
);
2090 void dns_transaction_notify(DnsTransaction
*t
, DnsTransaction
*source
) {
2094 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2095 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2096 the state is VALIDATING however, we should check if we are complete now. */
2098 if (t
->state
== DNS_TRANSACTION_VALIDATING
)
2099 dns_transaction_process_dnssec(t
);
2102 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction
*t
) {
2103 DnsResourceRecord
*rr
;
2108 /* Add all DNSKEY RRs from the answer that are validated by DS
2109 * RRs from the list of validated keys to the list of
2110 * validated keys. */
2112 DNS_ANSWER_FOREACH_IFINDEX(rr
, ifindex
, t
->answer
) {
2114 r
= dnssec_verify_dnskey_by_ds_search(rr
, t
->validated_keys
);
2120 /* If so, the DNSKEY is validated too. */
2121 r
= dns_answer_add_extend(&t
->validated_keys
, rr
, ifindex
, DNS_ANSWER_AUTHENTICATED
);
2129 static int dns_transaction_requires_rrsig(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2135 /* Checks if the RR we are looking for must be signed with an
2136 * RRSIG. This is used for positive responses. */
2138 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2141 if (dns_type_is_pseudo(rr
->key
->type
))
2144 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2150 switch (rr
->key
->type
) {
2152 case DNS_TYPE_RRSIG
:
2153 /* RRSIGs are the signatures themselves, they need no signing. */
2161 /* For SOA or NS RRs we look for a matching DS transaction */
2163 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2165 if (dt
->key
->class != rr
->key
->class)
2167 if (dt
->key
->type
!= DNS_TYPE_DS
)
2170 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2176 /* We found a DS transactions for the SOA/NS
2177 * RRs we are looking at. If it discovered signed DS
2178 * RRs, then we need to be signed, too. */
2180 if (!dt
->answer_authenticated
)
2183 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2186 /* We found nothing that proves this is safe to leave
2187 * this unauthenticated, hence ask inist on
2188 * authentication. */
2193 case DNS_TYPE_CNAME
:
2194 case DNS_TYPE_DNAME
: {
2195 const char *parent
= NULL
;
2200 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2202 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2205 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2207 if (dt
->key
->class != rr
->key
->class)
2209 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2213 parent
= dns_resource_key_name(rr
->key
);
2214 r
= dns_name_parent(&parent
);
2218 if (rr
->key
->type
== DNS_TYPE_DS
)
2221 /* A CNAME/DNAME without a parent? That's sooo weird. */
2222 log_debug("Transaction %" PRIu16
" claims CNAME/DNAME at root. Refusing.", t
->id
);
2227 r
= dns_name_equal(dns_resource_key_name(dt
->key
), parent
);
2233 return t
->answer_authenticated
;
2243 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2245 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2247 if (dt
->key
->class != rr
->key
->class)
2249 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2252 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2258 /* We found the transaction that was supposed to find
2259 * the SOA RR for us. It was successful, but found no
2260 * RR for us. This means we are not at a zone cut. In
2261 * this case, we require authentication if the SOA
2262 * lookup was authenticated too. */
2263 return t
->answer_authenticated
;
2270 static int dns_transaction_in_private_tld(DnsTransaction
*t
, const DnsResourceKey
*key
) {
2276 /* If DNSSEC downgrade mode is on, checks whether the
2277 * specified RR is one level below a TLD we have proven not to
2278 * exist. In such a case we assume that this is a private
2279 * domain, and permit it.
2281 * This detects cases like the Fritz!Box router networks. Each
2282 * Fritz!Box router serves a private "fritz.box" zone, in the
2283 * non-existing TLD "box". Requests for the "fritz.box" domain
2284 * are served by the router itself, while requests for the
2285 * "box" domain will result in NXDOMAIN.
2287 * Note that this logic is unable to detect cases where a
2288 * router serves a private DNS zone directly under
2289 * non-existing TLD. In such a case we cannot detect whether
2290 * the TLD is supposed to exist or not, as all requests we
2291 * make for it will be answered by the router's zone, and not
2292 * by the root zone. */
2296 if (t
->scope
->dnssec_mode
!= DNSSEC_ALLOW_DOWNGRADE
)
2297 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2299 tld
= dns_resource_key_name(key
);
2300 r
= dns_name_parent(&tld
);
2304 return false; /* Already the root domain */
2306 if (!dns_name_is_single_label(tld
))
2309 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2311 if (dt
->key
->class != key
->class)
2314 r
= dns_name_equal(dns_resource_key_name(dt
->key
), tld
);
2320 /* We found an auxiliary lookup we did for the TLD. If
2321 * that returned with NXDOMAIN, we know the TLD didn't
2322 * exist, and hence this might be a private zone. */
2324 return dt
->answer_rcode
== DNS_RCODE_NXDOMAIN
;
2330 static int dns_transaction_requires_nsec(DnsTransaction
*t
) {
2331 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2340 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2341 * this negative reply */
2343 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2346 if (dns_type_is_pseudo(t
->key
->type
))
2349 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
2355 r
= dns_transaction_in_private_tld(t
, t
->key
);
2359 /* The lookup is from a TLD that is proven not to
2360 * exist, and we are in downgrade mode, hence ignore
2361 * that fact that we didn't get any NSEC RRs.*/
2363 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2364 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2368 name
= dns_resource_key_name(t
->key
);
2370 if (t
->key
->type
== DNS_TYPE_DS
) {
2372 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2373 * hence check the parent SOA in this case. */
2375 r
= dns_name_parent(&name
);
2381 type
= DNS_TYPE_SOA
;
2383 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
))
2384 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2387 /* For all other negative replies, check for the SOA lookup */
2388 type
= DNS_TYPE_SOA
;
2390 /* For all other RRs we check the SOA on the same level to see
2391 * if it's signed. */
2393 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2395 if (dt
->key
->class != t
->key
->class)
2397 if (dt
->key
->type
!= type
)
2400 r
= dns_name_equal(dns_resource_key_name(dt
->key
), name
);
2406 return dt
->answer_authenticated
;
2409 /* If in doubt, require NSEC/NSEC3 */
2413 static int dns_transaction_dnskey_authenticated(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2414 DnsResourceRecord
*rrsig
;
2418 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2419 * the specified RRset is authenticated (i.e. has a matching
2422 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2428 DNS_ANSWER_FOREACH(rrsig
, t
->answer
) {
2432 r
= dnssec_key_match_rrsig(rr
->key
, rrsig
);
2438 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2440 if (dt
->key
->class != rr
->key
->class)
2443 if (dt
->key
->type
== DNS_TYPE_DNSKEY
) {
2445 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2451 /* OK, we found an auxiliary DNSKEY
2452 * lookup. If that lookup is
2453 * authenticated, report this. */
2455 if (dt
->answer_authenticated
)
2460 } else if (dt
->key
->type
== DNS_TYPE_DS
) {
2462 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2468 /* OK, we found an auxiliary DS
2469 * lookup. If that lookup is
2470 * authenticated and non-zero, we
2473 if (!dt
->answer_authenticated
)
2476 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2481 return found
? false : -ENXIO
;
2484 static int dns_transaction_known_signed(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2488 /* We know that the root domain is signed, hence if it appears
2489 * not to be signed, there's a problem with the DNS server */
2491 return rr
->key
->class == DNS_CLASS_IN
&&
2492 dns_name_is_root(dns_resource_key_name(rr
->key
));
2495 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction
*t
) {
2496 DnsResourceRecord
*rr
;
2501 /* Maybe warn the user that we encountered a revoked DNSKEY
2502 * for a key from our trust anchor. Note that we don't care
2503 * whether the DNSKEY can be authenticated or not. It's
2504 * sufficient if it is self-signed. */
2506 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2507 r
= dns_trust_anchor_check_revoked(&t
->scope
->manager
->trust_anchor
, rr
, t
->answer
);
2515 static int dns_transaction_invalidate_revoked_keys(DnsTransaction
*t
) {
2521 /* Removes all DNSKEY/DS objects from t->validated_keys that
2522 * our trust anchors database considers revoked. */
2525 DnsResourceRecord
*rr
;
2529 DNS_ANSWER_FOREACH(rr
, t
->validated_keys
) {
2530 r
= dns_trust_anchor_is_revoked(&t
->scope
->manager
->trust_anchor
, rr
);
2534 r
= dns_answer_remove_by_rr(&t
->validated_keys
, rr
);
2548 static int dns_transaction_copy_validated(DnsTransaction
*t
) {
2555 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
2557 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2559 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
2562 if (!dt
->answer_authenticated
)
2565 r
= dns_answer_extend(&t
->validated_keys
, dt
->answer
);
2574 DNSSEC_PHASE_DNSKEY
, /* Phase #1, only validate DNSKEYs */
2575 DNSSEC_PHASE_NSEC
, /* Phase #2, only validate NSEC+NSEC3 */
2576 DNSSEC_PHASE_ALL
, /* Phase #3, validate everything else */
2579 static int dnssec_validate_records(
2583 DnsAnswer
**validated
) {
2585 DnsResourceRecord
*rr
;
2588 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
2590 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2591 DnsResourceRecord
*rrsig
= NULL
;
2592 DnssecResult result
;
2594 switch (rr
->key
->type
) {
2595 case DNS_TYPE_RRSIG
:
2598 case DNS_TYPE_DNSKEY
:
2599 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
2600 if (phase
== DNSSEC_PHASE_NSEC
)
2605 case DNS_TYPE_NSEC3
:
2608 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
2609 if (phase
== DNSSEC_PHASE_DNSKEY
)
2614 /* We validate all other RRs only in the ALL phases */
2615 if (phase
!= DNSSEC_PHASE_ALL
)
2619 r
= dnssec_verify_rrset_search(t
->answer
, rr
->key
, t
->validated_keys
, USEC_INFINITY
, &result
, &rrsig
);
2623 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr
)), dnssec_result_to_string(result
));
2625 if (result
== DNSSEC_VALIDATED
) {
2627 if (rr
->key
->type
== DNS_TYPE_DNSKEY
) {
2628 /* If we just validated a DNSKEY RRset, then let's add these keys to
2629 * the set of validated keys for this transaction. */
2631 r
= dns_answer_copy_by_key(&t
->validated_keys
, t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
);
2635 /* Some of the DNSKEYs we just added might already have been revoked,
2636 * remove them again in that case. */
2637 r
= dns_transaction_invalidate_revoked_keys(t
);
2642 /* Add the validated RRset to the new list of validated
2643 * RRsets, and remove it from the unvalidated RRsets.
2644 * We mark the RRset as authenticated and cacheable. */
2645 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
);
2649 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_SECURE
, rr
->key
);
2651 /* Exit the loop, we dropped something from the answer, start from the beginning */
2655 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
2656 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
2657 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
2658 if (phase
!= DNSSEC_PHASE_ALL
)
2661 if (result
== DNSSEC_VALIDATED_WILDCARD
) {
2662 bool authenticated
= false;
2665 /* This RRset validated, but as a wildcard. This means we need
2666 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists.*/
2668 /* First step, determine the source of synthesis */
2669 r
= dns_resource_record_source(rrsig
, &source
);
2673 r
= dnssec_test_positive_wildcard(*validated
,
2674 dns_resource_key_name(rr
->key
),
2676 rrsig
->rrsig
.signer
,
2679 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
2681 result
= DNSSEC_INVALID
;
2683 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
,
2684 authenticated
? (DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
) : 0);
2688 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, rr
->key
);
2690 /* Exit the loop, we dropped something from the answer, start from the beginning */
2695 if (result
== DNSSEC_NO_SIGNATURE
) {
2696 r
= dns_transaction_requires_rrsig(t
, rr
);
2700 /* Data does not require signing. In that case, just copy it over,
2701 * but remember that this is by no means authenticated.*/
2702 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2706 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2710 r
= dns_transaction_known_signed(t
, rr
);
2714 /* This is an RR we know has to be signed. If it isn't this means
2715 * the server is not attaching RRSIGs, hence complain. */
2717 dns_server_packet_rrsig_missing(t
->server
, t
->current_feature_level
);
2719 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
2721 /* Downgrading is OK? If so, just consider the information unsigned */
2723 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2727 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2731 /* Otherwise, fail */
2732 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2736 r
= dns_transaction_in_private_tld(t
, rr
->key
);
2740 char s
[DNS_RESOURCE_KEY_STRING_MAX
];
2742 /* The data is from a TLD that is proven not to exist, and we are in downgrade
2743 * mode, hence ignore the fact that this was not signed. */
2745 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
2746 dns_resource_key_to_string(rr
->key
, s
, sizeof s
));
2748 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2752 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2759 DNSSEC_SIGNATURE_EXPIRED
,
2760 DNSSEC_UNSUPPORTED_ALGORITHM
)) {
2762 r
= dns_transaction_dnskey_authenticated(t
, rr
);
2763 if (r
< 0 && r
!= -ENXIO
)
2766 /* The DNSKEY transaction was not authenticated, this means there's
2767 * no DS for this, which means it's OK if no keys are found for this signature. */
2769 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2773 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2778 r
= dns_transaction_is_primary_response(t
, rr
);
2782 /* Look for a matching DNAME for this CNAME */
2783 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2787 /* Also look among the stuff we already validated */
2788 r
= dns_answer_has_dname_for_cname(*validated
, rr
);
2796 DNSSEC_SIGNATURE_EXPIRED
,
2797 DNSSEC_NO_SIGNATURE
))
2798 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, rr
->key
);
2799 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
2800 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, rr
->key
);
2802 /* This is a primary response to our question, and it failed validation.
2804 t
->answer_dnssec_result
= result
;
2808 /* This is a primary response, but we do have a DNAME RR
2809 * in the RR that can replay this CNAME, hence rely on
2810 * that, and we can remove the CNAME in favour of it. */
2813 /* This is just some auxiliary data. Just remove the RRset and continue. */
2814 r
= dns_answer_remove_by_key(&t
->answer
, rr
->key
);
2818 /* We dropped something from the answer, start from the beginning. */
2822 return 2; /* Finito. */
2825 int dns_transaction_validate_dnssec(DnsTransaction
*t
) {
2826 _cleanup_(dns_answer_unrefp
) DnsAnswer
*validated
= NULL
;
2828 DnsAnswerFlags flags
;
2830 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2834 /* We have now collected all DS and DNSKEY RRs in
2835 * t->validated_keys, let's see which RRs we can now
2836 * authenticate with that. */
2838 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2841 /* Already validated */
2842 if (t
->answer_dnssec_result
!= _DNSSEC_RESULT_INVALID
)
2845 /* Our own stuff needs no validation */
2846 if (IN_SET(t
->answer_source
, DNS_TRANSACTION_ZONE
, DNS_TRANSACTION_TRUST_ANCHOR
)) {
2847 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2848 t
->answer_authenticated
= true;
2852 /* Cached stuff is not affected by validation. */
2853 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
2856 if (!dns_transaction_dnssec_supported_full(t
)) {
2857 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
2858 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2859 log_debug("Not validating response for %" PRIu16
", server lacks DNSSEC support.", t
->id
);
2863 log_debug("Validating response from transaction %" PRIu16
" (%s).",
2865 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2867 /* First, see if this response contains any revoked trust
2868 * anchors we care about */
2869 r
= dns_transaction_check_revoked_trust_anchors(t
);
2873 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
2874 r
= dns_transaction_copy_validated(t
);
2878 /* Second, see if there are DNSKEYs we already know a
2879 * validated DS for. */
2880 r
= dns_transaction_validate_dnskey_by_ds(t
);
2884 /* Fourth, remove all DNSKEY and DS RRs again that our trust
2885 * anchor says are revoked. After all we might have marked
2886 * some keys revoked above, but they might still be lingering
2887 * in our validated_keys list. */
2888 r
= dns_transaction_invalidate_revoked_keys(t
);
2892 phase
= DNSSEC_PHASE_DNSKEY
;
2894 bool have_nsec
= false;
2896 r
= dnssec_validate_records(t
, phase
, &have_nsec
, &validated
);
2900 /* Try again as long as we managed to achieve something */
2904 if (phase
== DNSSEC_PHASE_DNSKEY
&& have_nsec
) {
2905 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
2906 phase
= DNSSEC_PHASE_NSEC
;
2910 if (phase
!= DNSSEC_PHASE_ALL
) {
2911 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
2912 * Note that in this third phase we start to remove RRs we couldn't validate. */
2913 phase
= DNSSEC_PHASE_ALL
;
2921 dns_answer_unref(t
->answer
);
2922 t
->answer
= validated
;
2925 /* At this point the answer only contains validated
2926 * RRsets. Now, let's see if it actually answers the question
2927 * we asked. If so, great! If it doesn't, then see if
2928 * NSEC/NSEC3 can prove this. */
2929 r
= dns_transaction_has_positive_answer(t
, &flags
);
2931 /* Yes, it answers the question! */
2933 if (flags
& DNS_ANSWER_AUTHENTICATED
) {
2934 /* The answer is fully authenticated, yay. */
2935 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2936 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
2937 t
->answer_authenticated
= true;
2939 /* The answer is not fully authenticated. */
2940 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
2941 t
->answer_authenticated
= false;
2944 } else if (r
== 0) {
2945 DnssecNsecResult nr
;
2946 bool authenticated
= false;
2948 /* Bummer! Let's check NSEC/NSEC3 */
2949 r
= dnssec_nsec_test(t
->answer
, t
->key
, &nr
, &authenticated
, &t
->answer_nsec_ttl
);
2955 case DNSSEC_NSEC_NXDOMAIN
:
2956 /* NSEC proves the domain doesn't exist. Very good. */
2957 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
2958 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2959 t
->answer_rcode
= DNS_RCODE_NXDOMAIN
;
2960 t
->answer_authenticated
= authenticated
;
2962 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
2965 case DNSSEC_NSEC_NODATA
:
2966 /* NSEC proves that there's no data here, very good. */
2967 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
2968 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2969 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
2970 t
->answer_authenticated
= authenticated
;
2972 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
2975 case DNSSEC_NSEC_OPTOUT
:
2976 /* NSEC3 says the data might not be signed */
2977 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
2978 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
2979 t
->answer_authenticated
= false;
2981 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
2984 case DNSSEC_NSEC_NO_RR
:
2985 /* No NSEC data? Bummer! */
2987 r
= dns_transaction_requires_nsec(t
);
2991 t
->answer_dnssec_result
= DNSSEC_NO_SIGNATURE
;
2992 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
2994 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
2995 t
->answer_authenticated
= false;
2996 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3001 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM
:
3002 /* We don't know the NSEC3 algorithm used? */
3003 t
->answer_dnssec_result
= DNSSEC_UNSUPPORTED_ALGORITHM
;
3004 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, t
->key
);
3007 case DNSSEC_NSEC_FOUND
:
3008 case DNSSEC_NSEC_CNAME
:
3009 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3010 t
->answer_dnssec_result
= DNSSEC_NSEC_MISMATCH
;
3011 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3015 assert_not_reached("Unexpected NSEC result.");
3022 static const char* const dns_transaction_state_table
[_DNS_TRANSACTION_STATE_MAX
] = {
3023 [DNS_TRANSACTION_NULL
] = "null",
3024 [DNS_TRANSACTION_PENDING
] = "pending",
3025 [DNS_TRANSACTION_VALIDATING
] = "validating",
3026 [DNS_TRANSACTION_RCODE_FAILURE
] = "rcode-failure",
3027 [DNS_TRANSACTION_SUCCESS
] = "success",
3028 [DNS_TRANSACTION_NO_SERVERS
] = "no-servers",
3029 [DNS_TRANSACTION_TIMEOUT
] = "timeout",
3030 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
] = "attempts-max-reached",
3031 [DNS_TRANSACTION_INVALID_REPLY
] = "invalid-reply",
3032 [DNS_TRANSACTION_ERRNO
] = "errno",
3033 [DNS_TRANSACTION_ABORTED
] = "aborted",
3034 [DNS_TRANSACTION_DNSSEC_FAILED
] = "dnssec-failed",
3035 [DNS_TRANSACTION_NO_TRUST_ANCHOR
] = "no-trust-anchor",
3036 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
] = "rr-type-unsupported",
3037 [DNS_TRANSACTION_NETWORK_DOWN
] = "network-down",
3038 [DNS_TRANSACTION_NOT_FOUND
] = "not-found",
3040 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state
, DnsTransactionState
);
3042 static const char* const dns_transaction_source_table
[_DNS_TRANSACTION_SOURCE_MAX
] = {
3043 [DNS_TRANSACTION_NETWORK
] = "network",
3044 [DNS_TRANSACTION_CACHE
] = "cache",
3045 [DNS_TRANSACTION_ZONE
] = "zone",
3046 [DNS_TRANSACTION_TRUST_ANCHOR
] = "trust-anchor",
3048 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source
, DnsTransactionSource
);