1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
3 #include "sd-messages.h"
6 #include "alloc-util.h"
7 #include "dns-domain.h"
8 #include "errno-list.h"
9 #include "errno-util.h"
11 #include "random-util.h"
12 #include "resolved-dns-cache.h"
13 #include "resolved-dns-transaction.h"
14 #include "resolved-dnstls.h"
15 #include "resolved-llmnr.h"
16 #include "string-table.h"
18 #define TRANSACTIONS_MAX 4096
19 #define TRANSACTION_TCP_TIMEOUT_USEC (10U*USEC_PER_SEC)
21 /* After how much time to repeat classic DNS requests */
22 #define DNS_TIMEOUT_USEC (SD_RESOLVED_QUERY_TIMEOUT_USEC / DNS_TRANSACTION_ATTEMPTS_MAX)
24 static void dns_transaction_reset_answer(DnsTransaction
*t
) {
27 t
->received
= dns_packet_unref(t
->received
);
28 t
->answer
= dns_answer_unref(t
->answer
);
30 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
31 t
->answer_source
= _DNS_TRANSACTION_SOURCE_INVALID
;
32 t
->answer_query_flags
= 0;
33 t
->answer_nsec_ttl
= UINT32_MAX
;
37 static void dns_transaction_flush_dnssec_transactions(DnsTransaction
*t
) {
42 while ((z
= set_steal_first(t
->dnssec_transactions
))) {
43 set_remove(z
->notify_transactions
, t
);
44 set_remove(z
->notify_transactions_done
, t
);
45 dns_transaction_gc(z
);
49 static void dns_transaction_close_connection(
51 bool use_graveyard
) { /* Set use_graveyard = false when you know the connection is already
52 * dead, for example because you got a connection error back from the
53 * kernel. In that case there's no point in keeping the fd around,
60 /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */
61 LIST_REMOVE(transactions_by_stream
, t
->stream
->transactions
, t
);
63 /* Remove packet in case it's still in the queue */
64 dns_packet_unref(ordered_set_remove(t
->stream
->write_queue
, t
->sent
));
66 t
->stream
= dns_stream_unref(t
->stream
);
69 t
->dns_udp_event_source
= sd_event_source_disable_unref(t
->dns_udp_event_source
);
71 /* If we have an UDP socket where we sent a packet, but never received one, then add it to the socket
72 * graveyard, instead of closing it right away. That way it will stick around for a moment longer,
73 * and the reply we might still get from the server will be eaten up instead of resulting in an ICMP
74 * port unreachable error message. */
76 if (use_graveyard
&& t
->dns_udp_fd
>= 0 && t
->sent
&& !t
->received
) {
77 r
= manager_add_socket_to_graveyard(t
->scope
->manager
, t
->dns_udp_fd
);
79 log_debug_errno(r
, "Failed to add UDP socket to graveyard, closing immediately: %m");
81 TAKE_FD(t
->dns_udp_fd
);
84 t
->dns_udp_fd
= safe_close(t
->dns_udp_fd
);
87 static void dns_transaction_stop_timeout(DnsTransaction
*t
) {
90 t
->timeout_event_source
= sd_event_source_disable_unref(t
->timeout_event_source
);
93 DnsTransaction
* dns_transaction_free(DnsTransaction
*t
) {
101 log_debug("Freeing transaction %" PRIu16
".", t
->id
);
103 dns_transaction_close_connection(t
, true);
104 dns_transaction_stop_timeout(t
);
106 dns_packet_unref(t
->sent
);
107 dns_transaction_reset_answer(t
);
109 dns_server_unref(t
->server
);
113 DnsTransaction
*first
;
115 first
= hashmap_get(t
->scope
->transactions_by_key
, t
->key
);
116 LIST_REMOVE(transactions_by_key
, first
, t
);
118 hashmap_replace(t
->scope
->transactions_by_key
, first
->key
, first
);
120 hashmap_remove(t
->scope
->transactions_by_key
, t
->key
);
123 LIST_REMOVE(transactions_by_scope
, t
->scope
->transactions
, t
);
126 hashmap_remove(t
->scope
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
));
129 while ((c
= set_steal_first(t
->notify_query_candidates
)))
130 set_remove(c
->transactions
, t
);
131 set_free(t
->notify_query_candidates
);
133 while ((c
= set_steal_first(t
->notify_query_candidates_done
)))
134 set_remove(c
->transactions
, t
);
135 set_free(t
->notify_query_candidates_done
);
137 while ((i
= set_steal_first(t
->notify_zone_items
)))
138 i
->probe_transaction
= NULL
;
139 set_free(t
->notify_zone_items
);
141 while ((i
= set_steal_first(t
->notify_zone_items_done
)))
142 i
->probe_transaction
= NULL
;
143 set_free(t
->notify_zone_items_done
);
145 while ((z
= set_steal_first(t
->notify_transactions
)))
146 set_remove(z
->dnssec_transactions
, t
);
147 set_free(t
->notify_transactions
);
149 while ((z
= set_steal_first(t
->notify_transactions_done
)))
150 set_remove(z
->dnssec_transactions
, t
);
151 set_free(t
->notify_transactions_done
);
153 dns_transaction_flush_dnssec_transactions(t
);
154 set_free(t
->dnssec_transactions
);
156 dns_answer_unref(t
->validated_keys
);
157 dns_resource_key_unref(t
->key
);
158 dns_packet_unref(t
->bypass
);
163 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction
*, dns_transaction_free
);
165 DnsTransaction
* dns_transaction_gc(DnsTransaction
*t
) {
168 /* Returns !NULL if we can't gc yet. */
173 if (set_isempty(t
->notify_query_candidates
) &&
174 set_isempty(t
->notify_query_candidates_done
) &&
175 set_isempty(t
->notify_zone_items
) &&
176 set_isempty(t
->notify_zone_items_done
) &&
177 set_isempty(t
->notify_transactions
) &&
178 set_isempty(t
->notify_transactions_done
))
179 return dns_transaction_free(t
);
184 static uint16_t pick_new_id(Manager
*m
) {
187 /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the
188 * number of transactions, and it's much lower than the space of IDs. */
190 assert_cc(TRANSACTIONS_MAX
< 0xFFFF);
193 random_bytes(&new_id
, sizeof(new_id
));
194 while (new_id
== 0 ||
195 hashmap_get(m
->dns_transactions
, UINT_TO_PTR(new_id
)));
202 DnsResourceKey
*key
) {
204 /* Don't allow looking up invalid or pseudo RRs */
205 if (!dns_type_is_valid_query(key
->type
))
207 if (dns_type_is_obsolete(key
->type
))
210 /* We only support the IN class */
211 if (!IN_SET(key
->class, DNS_CLASS_IN
, DNS_CLASS_ANY
))
214 /* Don't allows DNSSEC RRs to be looked up via LLMNR/mDNS. They don't really make sense
215 * there, and it speeds up our queries if we refuse this early */
216 if (scope
->protocol
!= DNS_PROTOCOL_DNS
&&
217 dns_type_is_dnssec(key
->type
))
223 int dns_transaction_new(
224 DnsTransaction
**ret
,
228 uint64_t query_flags
) {
230 _cleanup_(dns_transaction_freep
) DnsTransaction
*t
= NULL
;
246 r
= dns_packet_validate_query(bypass
);
250 DNS_QUESTION_FOREACH(qk
, bypass
->question
) {
257 if (hashmap_size(s
->manager
->dns_transactions
) >= TRANSACTIONS_MAX
)
260 r
= hashmap_ensure_allocated(&s
->manager
->dns_transactions
, NULL
);
265 r
= hashmap_ensure_allocated(&s
->transactions_by_key
, &dns_resource_key_hash_ops
);
270 t
= new(DnsTransaction
, 1);
274 *t
= (DnsTransaction
) {
276 .answer_source
= _DNS_TRANSACTION_SOURCE_INVALID
,
277 .answer_dnssec_result
= _DNSSEC_RESULT_INVALID
,
278 .answer_nsec_ttl
= UINT32_MAX
,
279 .key
= dns_resource_key_ref(key
),
280 .query_flags
= query_flags
,
281 .bypass
= dns_packet_ref(bypass
),
282 .current_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
,
283 .clamp_feature_level_servfail
= _DNS_SERVER_FEATURE_LEVEL_INVALID
,
284 .clamp_feature_level_nxdomain
= _DNS_SERVER_FEATURE_LEVEL_INVALID
,
285 .id
= pick_new_id(s
->manager
),
288 r
= hashmap_put(s
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
), t
);
295 DnsTransaction
*first
;
297 first
= hashmap_get(s
->transactions_by_key
, t
->key
);
298 LIST_PREPEND(transactions_by_key
, first
, t
);
300 r
= hashmap_replace(s
->transactions_by_key
, first
->key
, first
);
302 LIST_REMOVE(transactions_by_key
, first
, t
);
307 LIST_PREPEND(transactions_by_scope
, s
->transactions
, t
);
310 s
->manager
->n_transactions_total
++;
319 static void dns_transaction_shuffle_id(DnsTransaction
*t
) {
323 /* Pick a new ID for this transaction. */
325 new_id
= pick_new_id(t
->scope
->manager
);
326 assert_se(hashmap_remove_and_put(t
->scope
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
), UINT_TO_PTR(new_id
), t
) >= 0);
328 log_debug("Transaction %" PRIu16
" is now %" PRIu16
".", t
->id
, new_id
);
331 /* Make sure we generate a new packet with the new ID */
332 t
->sent
= dns_packet_unref(t
->sent
);
335 static void dns_transaction_tentative(DnsTransaction
*t
, DnsPacket
*p
) {
336 _cleanup_free_
char *pretty
= NULL
;
337 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
342 assert(t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
);
344 if (manager_packet_from_local_address(t
->scope
->manager
, p
) != 0)
347 (void) in_addr_to_string(p
->family
, &p
->sender
, &pretty
);
349 log_debug("Transaction %" PRIu16
" for <%s> on scope %s on %s/%s got tentative packet from %s.",
351 dns_resource_key_to_string(dns_transaction_key(t
), key_str
, sizeof key_str
),
352 dns_protocol_to_string(t
->scope
->protocol
),
353 t
->scope
->link
? t
->scope
->link
->ifname
: "*",
354 af_to_name_short(t
->scope
->family
),
357 /* RFC 4795, Section 4.1 says that the peer with the
358 * lexicographically smaller IP address loses */
359 if (memcmp(&p
->sender
, &p
->destination
, FAMILY_ADDRESS_SIZE(p
->family
)) >= 0) {
360 log_debug("Peer has lexicographically larger IP address and thus lost in the conflict.");
364 log_debug("We have the lexicographically larger IP address and thus lost in the conflict.");
368 while ((z
= set_first(t
->notify_zone_items
))) {
369 /* First, make sure the zone item drops the reference
371 dns_zone_item_probe_stop(z
);
373 /* Secondly, report this as conflict, so that we might
374 * look for a different hostname */
375 dns_zone_item_conflict(z
);
379 dns_transaction_gc(t
);
382 void dns_transaction_complete(DnsTransaction
*t
, DnsTransactionState state
) {
383 DnsQueryCandidate
*c
;
387 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
390 assert(!DNS_TRANSACTION_IS_LIVE(state
));
392 if (state
== DNS_TRANSACTION_DNSSEC_FAILED
) {
393 dns_resource_key_to_string(dns_transaction_key(t
), key_str
, sizeof key_str
);
395 log_struct(LOG_NOTICE
,
396 "MESSAGE_ID=" SD_MESSAGE_DNSSEC_FAILURE_STR
,
397 LOG_MESSAGE("DNSSEC validation failed for question %s: %s", key_str
, dnssec_result_to_string(t
->answer_dnssec_result
)),
398 "DNS_TRANSACTION=%" PRIu16
, t
->id
,
399 "DNS_QUESTION=%s", key_str
,
400 "DNSSEC_RESULT=%s", dnssec_result_to_string(t
->answer_dnssec_result
),
401 "DNS_SERVER=%s", strna(dns_server_string_full(t
->server
)),
402 "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t
->server
->possible_feature_level
));
405 /* Note that this call might invalidate the query. Callers
406 * should hence not attempt to access the query or transaction
407 * after calling this function. */
409 if (state
== DNS_TRANSACTION_ERRNO
)
410 st
= errno_to_name(t
->answer_errno
);
412 st
= dns_transaction_state_to_string(state
);
414 log_debug("%s transaction %" PRIu16
" for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s; %s).",
415 t
->bypass
? "Bypass" : "Regular",
417 dns_resource_key_to_string(dns_transaction_key(t
), key_str
, sizeof key_str
),
418 dns_protocol_to_string(t
->scope
->protocol
),
419 t
->scope
->link
? t
->scope
->link
->ifname
: "*",
420 af_to_name_short(t
->scope
->family
),
422 t
->answer_source
< 0 ? "none" : dns_transaction_source_to_string(t
->answer_source
),
423 FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_VALIDATE
) ? "not validated" :
424 (FLAGS_SET(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
) ? "authenticated" : "unsigned"),
425 FLAGS_SET(t
->answer_query_flags
, SD_RESOLVED_CONFIDENTIAL
) ? "confidential" : "non-confidential");
429 dns_transaction_close_connection(t
, true);
430 dns_transaction_stop_timeout(t
);
432 /* Notify all queries that are interested, but make sure the
433 * transaction isn't freed while we are still looking at it */
436 SET_FOREACH_MOVE(c
, t
->notify_query_candidates_done
, t
->notify_query_candidates
)
437 dns_query_candidate_notify(c
);
438 SWAP_TWO(t
->notify_query_candidates
, t
->notify_query_candidates_done
);
440 SET_FOREACH_MOVE(z
, t
->notify_zone_items_done
, t
->notify_zone_items
)
441 dns_zone_item_notify(z
);
442 SWAP_TWO(t
->notify_zone_items
, t
->notify_zone_items_done
);
443 if (t
->probing
&& t
->state
== DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
)
444 (void) dns_scope_announce(t
->scope
, false);
446 SET_FOREACH_MOVE(d
, t
->notify_transactions_done
, t
->notify_transactions
)
447 dns_transaction_notify(d
, t
);
448 SWAP_TWO(t
->notify_transactions
, t
->notify_transactions_done
);
451 dns_transaction_gc(t
);
454 static void dns_transaction_complete_errno(DnsTransaction
*t
, int error
) {
458 t
->answer_errno
= abs(error
);
459 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
462 static int dns_transaction_pick_server(DnsTransaction
*t
) {
466 assert(t
->scope
->protocol
== DNS_PROTOCOL_DNS
);
468 /* Pick a DNS server and a feature level for it. */
470 server
= dns_scope_get_dns_server(t
->scope
);
474 /* If we changed the server invalidate the feature level clamping, as the new server might have completely
475 * different properties. */
476 if (server
!= t
->server
) {
477 t
->clamp_feature_level_servfail
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
478 t
->clamp_feature_level_nxdomain
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
481 t
->current_feature_level
= dns_server_possible_feature_level(server
);
483 /* Clamp the feature level if that is requested. */
484 if (t
->clamp_feature_level_servfail
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
&&
485 t
->current_feature_level
> t
->clamp_feature_level_servfail
)
486 t
->current_feature_level
= t
->clamp_feature_level_servfail
;
487 if (t
->clamp_feature_level_nxdomain
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
&&
488 t
->current_feature_level
> t
->clamp_feature_level_nxdomain
)
489 t
->current_feature_level
= t
->clamp_feature_level_nxdomain
;
491 log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t
->current_feature_level
), t
->id
);
493 if (server
== t
->server
)
496 dns_server_unref(t
->server
);
497 t
->server
= dns_server_ref(server
);
499 t
->n_picked_servers
++;
501 log_debug("Using DNS server %s for transaction %u.", strna(dns_server_string_full(t
->server
)), t
->id
);
506 static void dns_transaction_retry(DnsTransaction
*t
, bool next_server
) {
511 /* Retries the transaction as it is, possibly on a different server */
513 if (next_server
&& t
->scope
->protocol
== DNS_PROTOCOL_DNS
)
514 log_debug("Retrying transaction %" PRIu16
", after switching servers.", t
->id
);
516 log_debug("Retrying transaction %" PRIu16
".", t
->id
);
518 /* Before we try again, switch to a new server. */
520 dns_scope_next_dns_server(t
->scope
, t
->server
);
522 r
= dns_transaction_go(t
);
524 dns_transaction_complete_errno(t
, r
);
527 static bool dns_transaction_limited_retry(DnsTransaction
*t
) {
530 /* If we haven't tried all different servers yet, let's try again with a different server */
532 if (t
->n_picked_servers
>= dns_scope_get_n_dns_servers(t
->scope
))
535 dns_transaction_retry(t
, /* next_server= */ true);
539 static int dns_transaction_maybe_restart(DnsTransaction
*t
) {
544 /* Restarts the transaction, under a new ID if the feature level of the server changed since we first
545 * tried, without changing DNS server. Returns > 0 if the transaction was restarted, 0 if not. */
550 if (t
->current_feature_level
<= dns_server_possible_feature_level(t
->server
))
553 /* The server's current feature level is lower than when we sent the original query. We learnt something from
554 the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to
555 restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include
556 OPT RR or DO bit. One of these cases is documented here, for example:
557 https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
559 log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
560 dns_transaction_shuffle_id(t
);
562 r
= dns_transaction_go(t
);
569 static void on_transaction_stream_error(DnsTransaction
*t
, int error
) {
572 dns_transaction_close_connection(t
, true);
574 if (ERRNO_IS_DISCONNECT(error
)) {
575 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
) {
576 /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the
577 * question on this scope. */
578 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
582 dns_transaction_retry(t
, true);
586 dns_transaction_complete_errno(t
, error
);
589 static int dns_transaction_on_stream_packet(DnsTransaction
*t
, DnsStream
*s
, DnsPacket
*p
) {
596 encrypted
= s
->encrypted
;
598 dns_transaction_close_connection(t
, true);
600 if (dns_packet_validate_reply(p
) <= 0) {
601 log_debug("Invalid TCP reply packet.");
602 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
606 dns_scope_check_conflicts(t
->scope
, p
);
609 dns_transaction_process_reply(t
, p
, encrypted
);
612 /* If the response wasn't useful, then complete the transition
613 * now. After all, we are the worst feature set now with TCP
614 * sockets, and there's really no point in retrying. */
615 if (t
->state
== DNS_TRANSACTION_PENDING
)
616 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
618 dns_transaction_gc(t
);
623 static int on_stream_complete(DnsStream
*s
, int error
) {
626 if (ERRNO_IS_DISCONNECT(error
) && s
->protocol
!= DNS_PROTOCOL_LLMNR
) {
627 log_debug_errno(error
, "Connection failure for DNS TCP stream: %m");
629 if (s
->transactions
) {
633 dns_server_packet_lost(t
->server
, IPPROTO_TCP
, t
->current_feature_level
);
638 LIST_FOREACH(transactions_by_stream
, t
, s
->transactions
)
639 on_transaction_stream_error(t
, error
);
644 static int on_stream_packet(DnsStream
*s
, DnsPacket
*p
) {
651 t
= hashmap_get(s
->manager
->dns_transactions
, UINT_TO_PTR(DNS_PACKET_ID(p
)));
652 if (t
&& t
->stream
== s
) /* Validate that the stream we got this on actually is the stream the
653 * transaction was using. */
654 return dns_transaction_on_stream_packet(t
, s
, p
);
656 /* Ignore incorrect transaction id as an old transaction can have been canceled. */
657 log_debug("Received unexpected TCP reply packet with id %" PRIu16
", ignoring.", DNS_PACKET_ID(p
));
661 static uint16_t dns_transaction_port(DnsTransaction
*t
) {
664 if (t
->server
->port
> 0)
665 return t
->server
->port
;
667 return DNS_SERVER_FEATURE_LEVEL_IS_TLS(t
->current_feature_level
) ? 853 : 53;
670 static int dns_transaction_emit_tcp(DnsTransaction
*t
) {
671 usec_t stream_timeout_usec
= DNS_STREAM_DEFAULT_TIMEOUT_USEC
;
672 _cleanup_(dns_stream_unrefp
) DnsStream
*s
= NULL
;
673 _cleanup_close_
int fd
= -1;
674 union sockaddr_union sa
;
681 dns_transaction_close_connection(t
, true);
683 switch (t
->scope
->protocol
) {
685 case DNS_PROTOCOL_DNS
:
686 r
= dns_transaction_pick_server(t
);
690 if (manager_server_is_stub(t
->scope
->manager
, t
->server
))
694 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(dns_transaction_key(t
)->type
))
697 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
702 if (t
->server
->stream
&& (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t
->current_feature_level
) == t
->server
->stream
->encrypted
))
703 s
= dns_stream_ref(t
->server
->stream
);
705 fd
= dns_scope_socket_tcp(t
->scope
, AF_UNSPEC
, NULL
, t
->server
, dns_transaction_port(t
), &sa
);
707 /* Lower timeout in DNS-over-TLS opportunistic mode. In environments where DoT is blocked
708 * without ICMP response overly long delays when contacting DoT servers are nasty, in
709 * particular if multiple DNS servers are defined which we try in turn and all are
710 * blocked. Hence, substantially lower the timeout in that case. */
711 if (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t
->current_feature_level
) &&
712 dns_server_get_dns_over_tls_mode(t
->server
) == DNS_OVER_TLS_OPPORTUNISTIC
)
713 stream_timeout_usec
= DNS_STREAM_OPPORTUNISTIC_TLS_TIMEOUT_USEC
;
715 type
= DNS_STREAM_LOOKUP
;
718 case DNS_PROTOCOL_LLMNR
:
719 /* When we already received a reply to this (but it was truncated), send to its sender address */
721 fd
= dns_scope_socket_tcp(t
->scope
, t
->received
->family
, &t
->received
->sender
, NULL
, t
->received
->sender_port
, &sa
);
723 union in_addr_union address
;
724 int family
= AF_UNSPEC
;
726 /* Otherwise, try to talk to the owner of a
727 * the IP address, in case this is a reverse
730 r
= dns_name_address(dns_resource_key_name(dns_transaction_key(t
)), &family
, &address
);
735 if (family
!= t
->scope
->family
)
738 fd
= dns_scope_socket_tcp(t
->scope
, family
, &address
, NULL
, LLMNR_PORT
, &sa
);
741 type
= DNS_STREAM_LLMNR_SEND
;
745 return -EAFNOSUPPORT
;
752 r
= dns_stream_new(t
->scope
->manager
, &s
, type
, t
->scope
->protocol
, fd
, &sa
,
753 on_stream_packet
, on_stream_complete
, stream_timeout_usec
);
759 #if ENABLE_DNS_OVER_TLS
760 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
&&
761 DNS_SERVER_FEATURE_LEVEL_IS_TLS(t
->current_feature_level
)) {
764 r
= dnstls_stream_connect_tls(s
, t
->server
);
771 dns_server_unref_stream(t
->server
);
772 s
->server
= dns_server_ref(t
->server
);
773 t
->server
->stream
= dns_stream_ref(s
);
776 /* The interface index is difficult to determine if we are
777 * connecting to the local host, hence fill this in right away
778 * instead of determining it from the socket */
779 s
->ifindex
= dns_scope_ifindex(t
->scope
);
782 t
->stream
= TAKE_PTR(s
);
783 LIST_PREPEND(transactions_by_stream
, t
->stream
->transactions
, t
);
785 r
= dns_stream_write_packet(t
->stream
, t
->sent
);
787 dns_transaction_close_connection(t
, /* use_graveyard= */ false);
791 dns_transaction_reset_answer(t
);
793 t
->tried_stream
= true;
798 static void dns_transaction_cache_answer(DnsTransaction
*t
) {
801 /* For mDNS we cache whenever we get the packet, rather than
802 * in each transaction. */
803 if (!IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
))
806 /* Caching disabled? */
807 if (t
->scope
->manager
->enable_cache
== DNS_CACHE_MODE_NO
)
810 /* If validation is turned off for this transaction, but DNSSEC is on, then let's not cache this */
811 if (FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_VALIDATE
) && t
->scope
->dnssec_mode
!= DNSSEC_NO
)
814 /* Packet from localhost? */
815 if (!t
->scope
->manager
->cache_from_localhost
&&
816 in_addr_is_localhost(t
->received
->family
, &t
->received
->sender
) != 0)
819 dns_cache_put(&t
->scope
->cache
,
820 t
->scope
->manager
->enable_cache
,
821 dns_transaction_key(t
),
824 DNS_PACKET_CD(t
->received
) ? t
->received
: NULL
, /* only cache full packets with CD on,
825 * since our usecase for caching them
826 * is "bypass" mode which is only
827 * enabled for CD packets. */
828 t
->answer_query_flags
,
829 t
->answer_dnssec_result
,
832 &t
->received
->sender
);
835 static bool dns_transaction_dnssec_is_live(DnsTransaction
*t
) {
840 SET_FOREACH(dt
, t
->dnssec_transactions
)
841 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
847 static int dns_transaction_dnssec_ready(DnsTransaction
*t
) {
853 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
854 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
856 SET_FOREACH(dt
, t
->dnssec_transactions
) {
860 case DNS_TRANSACTION_NULL
:
861 case DNS_TRANSACTION_PENDING
:
862 case DNS_TRANSACTION_VALIDATING
:
866 case DNS_TRANSACTION_RCODE_FAILURE
:
867 if (!IN_SET(dt
->answer_rcode
, DNS_RCODE_NXDOMAIN
, DNS_RCODE_SERVFAIL
)) {
868 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt
->answer_rcode
));
872 /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers
873 * erroneously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS
874 * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar
875 * RRs to make unsigned proofs. */
877 case DNS_TRANSACTION_SUCCESS
:
881 case DNS_TRANSACTION_DNSSEC_FAILED
:
882 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
883 * validation result */
885 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt
->answer_dnssec_result
));
886 t
->answer_dnssec_result
= dt
->answer_dnssec_result
; /* Copy error code over */
887 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
891 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt
->state
));
896 /* All is ready, we can go and validate */
900 /* Some auxiliary DNSSEC transaction failed for some reason. Maybe we learned something about the
901 * server due to this failure, and the feature level is now different? Let's see and restart the
902 * transaction if so. If not, let's propagate the auxiliary failure.
904 * This is particularly relevant if an auxiliary request figured out that DNSSEC doesn't work, and we
905 * are in permissive DNSSEC mode, and thus should restart things without DNSSEC magic. */
906 r
= dns_transaction_maybe_restart(t
);
910 return 0; /* don't validate just yet, we restarted things */
912 t
->answer_dnssec_result
= DNSSEC_FAILED_AUXILIARY
;
913 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
917 static void dns_transaction_process_dnssec(DnsTransaction
*t
) {
922 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
923 r
= dns_transaction_dnssec_ready(t
);
926 if (r
== 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
929 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
930 * restart the lookup immediately. */
931 r
= dns_transaction_maybe_restart(t
);
934 if (r
> 0) /* Transaction got restarted... */
937 /* All our auxiliary DNSSEC transactions are complete now. Try
938 * to validate our RRset now. */
939 r
= dns_transaction_validate_dnssec(t
);
941 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
947 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
&&
948 t
->scope
->dnssec_mode
== DNSSEC_YES
) {
950 /* We are not in automatic downgrade mode, and the server is bad. Let's try a different server, maybe
953 if (dns_transaction_limited_retry(t
))
956 /* OK, let's give up, apparently all servers we tried didn't work. */
957 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
961 if (!IN_SET(t
->answer_dnssec_result
,
962 _DNSSEC_RESULT_INVALID
, /* No DNSSEC validation enabled */
963 DNSSEC_VALIDATED
, /* Answer is signed and validated successfully */
964 DNSSEC_UNSIGNED
, /* Answer is right-fully unsigned */
965 DNSSEC_INCOMPATIBLE_SERVER
)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
966 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
970 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
)
971 dns_server_warn_downgrade(t
->server
);
973 dns_transaction_cache_answer(t
);
975 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
976 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
978 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
983 dns_transaction_complete_errno(t
, r
);
986 static int dns_transaction_has_positive_answer(DnsTransaction
*t
, DnsAnswerFlags
*flags
) {
991 /* Checks whether the answer is positive, i.e. either a direct
992 * answer to the question, or a CNAME/DNAME for it */
994 r
= dns_answer_match_key(t
->answer
, dns_transaction_key(t
), flags
);
998 r
= dns_answer_find_cname_or_dname(t
->answer
, dns_transaction_key(t
), NULL
, flags
);
1005 static int dns_transaction_fix_rcode(DnsTransaction
*t
) {
1010 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
1011 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
1012 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
1013 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
1014 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
1015 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
1016 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
1017 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
1018 * incomplete CNAME/DNAME chain.
1020 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
1021 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
1024 if (t
->answer_rcode
!= DNS_RCODE_NXDOMAIN
)
1027 r
= dns_transaction_has_positive_answer(t
, NULL
);
1031 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1035 void dns_transaction_process_reply(DnsTransaction
*t
, DnsPacket
*p
, bool encrypted
) {
1036 bool retry_with_tcp
= false;
1042 assert(t
->scope
->manager
);
1044 if (t
->state
!= DNS_TRANSACTION_PENDING
)
1047 /* Note that this call might invalidate the query. Callers
1048 * should hence not attempt to access the query or transaction
1049 * after calling this function. */
1051 log_debug("Processing incoming packet of size %zu on transaction %" PRIu16
" (rcode=%s).",
1053 t
->id
, dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
1055 switch (t
->scope
->protocol
) {
1057 case DNS_PROTOCOL_LLMNR
:
1058 /* For LLMNR we will not accept any packets from other interfaces */
1060 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
1063 if (p
->family
!= t
->scope
->family
)
1066 /* Tentative packets are not full responses but still
1067 * useful for identifying uniqueness conflicts during
1069 if (DNS_PACKET_LLMNR_T(p
)) {
1070 dns_transaction_tentative(t
, p
);
1076 case DNS_PROTOCOL_MDNS
:
1077 /* For mDNS we will not accept any packets from other interfaces */
1079 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
1082 if (p
->family
!= t
->scope
->family
)
1087 case DNS_PROTOCOL_DNS
:
1088 /* Note that we do not need to verify the
1089 * addresses/port numbers of incoming traffic, as we
1090 * invoked connect() on our UDP socket in which case
1091 * the kernel already does the needed verification for
1096 assert_not_reached();
1099 if (t
->received
!= p
) {
1100 dns_packet_unref(t
->received
);
1101 t
->received
= dns_packet_ref(p
);
1104 t
->answer_source
= DNS_TRANSACTION_NETWORK
;
1106 if (p
->ipproto
== IPPROTO_TCP
) {
1107 if (DNS_PACKET_TC(p
)) {
1108 /* Truncated via TCP? Somebody must be fucking with us */
1109 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1113 if (DNS_PACKET_ID(p
) != t
->id
) {
1114 /* Not the reply to our query? Somebody must be fucking with us */
1115 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1120 switch (t
->scope
->protocol
) {
1122 case DNS_PROTOCOL_DNS
:
1126 IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_FORMERR
, DNS_RCODE_SERVFAIL
, DNS_RCODE_NOTIMP
)) {
1128 /* Request failed, immediately try again with reduced features */
1130 if (t
->current_feature_level
<= DNS_SERVER_FEATURE_LEVEL_UDP
) {
1132 /* This was already at UDP feature level? If so, it doesn't make sense to downgrade
1133 * this transaction anymore, but let's see if it might make sense to send the request
1134 * to a different DNS server instead. If not let's process the response, and accept the
1135 * rcode. Note that we don't retry on TCP, since that's a suitable way to mitigate
1136 * packet loss, but is not going to give us better rcodes should we actually have
1137 * managed to get them already at UDP level. */
1139 if (dns_transaction_limited_retry(t
))
1142 /* Give up, accept the rcode */
1143 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
1147 /* SERVFAIL can happen for many reasons and may be transient.
1148 * To avoid unnecessary downgrades retry once with the initial level.
1149 * Check for clamp_feature_level_servfail having an invalid value as a sign that this is the
1150 * first attempt to downgrade. If so, clamp to the current value so that the transaction
1151 * is retried without actually downgrading. If the next try also fails we will downgrade by
1152 * hitting the else branch below. */
1153 if (DNS_PACKET_RCODE(p
) == DNS_RCODE_SERVFAIL
&&
1154 t
->clamp_feature_level_servfail
< 0) {
1155 t
->clamp_feature_level_servfail
= t
->current_feature_level
;
1156 log_debug("Server returned error %s, retrying transaction.",
1157 dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
1159 /* Reduce this feature level by one and try again. */
1160 switch (t
->current_feature_level
) {
1161 case DNS_SERVER_FEATURE_LEVEL_TLS_DO
:
1162 t
->clamp_feature_level_servfail
= DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN
;
1164 case DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN
+ 1:
1165 /* Skip plain TLS when TLS is not supported */
1166 t
->clamp_feature_level_servfail
= DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN
- 1;
1169 t
->clamp_feature_level_servfail
= t
->current_feature_level
- 1;
1172 log_debug("Server returned error %s, retrying transaction with reduced feature level %s.",
1173 dns_rcode_to_string(DNS_PACKET_RCODE(p
)),
1174 dns_server_feature_level_to_string(t
->clamp_feature_level_servfail
));
1177 dns_transaction_retry(t
, false /* use the same server */);
1181 if (DNS_PACKET_RCODE(p
) == DNS_RCODE_REFUSED
) {
1182 /* This server refused our request? If so, try again, use a different server */
1183 log_debug("Server returned REFUSED, switching servers, and retrying.");
1185 if (dns_transaction_limited_retry(t
))
1191 if (DNS_PACKET_TC(p
))
1192 dns_server_packet_truncated(t
->server
, t
->current_feature_level
);
1196 case DNS_PROTOCOL_LLMNR
:
1197 case DNS_PROTOCOL_MDNS
:
1198 dns_scope_packet_received(t
->scope
, p
->timestamp
- t
->start_usec
);
1202 assert_not_reached();
1205 if (DNS_PACKET_TC(p
)) {
1207 /* Truncated packets for mDNS are not allowed. Give up immediately. */
1208 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
) {
1209 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1213 /* Response was truncated, let's try again with good old TCP */
1214 log_debug("Reply truncated, retrying via TCP.");
1215 retry_with_tcp
= true;
1217 } else if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
&&
1218 DNS_PACKET_IS_FRAGMENTED(p
)) {
1220 /* Report the fragment size, so that we downgrade from LARGE to regular EDNS0 if needed */
1222 dns_server_packet_udp_fragmented(t
->server
, dns_packet_size_unfragmented(p
));
1224 if (t
->current_feature_level
> DNS_SERVER_FEATURE_LEVEL_UDP
) {
1225 /* Packet was fragmented. Let's retry with TCP to avoid fragmentation attack
1226 * issues. (We don't do that on the lowest feature level however, since crappy DNS
1227 * servers often do not implement TCP, hence falling back to TCP on fragmentation is
1228 * counter-productive there.) */
1230 log_debug("Reply fragmented, retrying via TCP. (Largest fragment size: %zu; Datagram size: %zu)",
1231 p
->fragsize
, p
->size
);
1232 retry_with_tcp
= true;
1236 if (retry_with_tcp
) {
1237 r
= dns_transaction_emit_tcp(t
);
1239 /* No servers found? Damn! */
1240 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
1243 if (r
== -EOPNOTSUPP
) {
1244 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1245 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
1249 /* On LLMNR, if we cannot connect to the host,
1250 * we immediately give up */
1251 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1254 /* On DNS, couldn't send? Try immediately again, with a new server */
1255 if (dns_transaction_limited_retry(t
))
1258 /* No new server to try, give up */
1259 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1265 /* After the superficial checks, actually parse the message. */
1266 r
= dns_packet_extract(p
);
1269 dns_server_packet_invalid(t
->server
, t
->current_feature_level
);
1271 r
= dns_transaction_maybe_restart(t
);
1274 if (r
> 0) /* Transaction got restarted... */
1278 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1282 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
&&
1284 DNS_PACKET_RCODE(p
) == DNS_RCODE_NXDOMAIN
&&
1285 p
->opt
&& !DNS_PACKET_DO(p
) &&
1286 DNS_SERVER_FEATURE_LEVEL_IS_EDNS0(t
->current_feature_level
) &&
1287 DNS_SERVER_FEATURE_LEVEL_IS_UDP(t
->current_feature_level
) &&
1288 t
->scope
->dnssec_mode
!= DNSSEC_YES
) {
1290 /* Some captive portals are special in that the Aruba/Datavalet hardware will miss
1291 * replacing the packets with the local server IP to point to the authenticated side
1292 * of the network if EDNS0 is enabled. Instead they return NXDOMAIN, with DO bit set
1293 * to zero... nothing to see here, yet respond with the captive portal IP, when using
1294 * the more simple UDP level.
1296 * Common portal names that fail like so are:
1297 * secure.datavalet.io
1298 * securelogin.arubanetworks.com
1299 * securelogin.networks.mycompany.com
1301 * Thus retry NXDOMAIN RCODES with a lower feature level.
1303 * Do not lower the server's tracked feature level, as the captive portal should not
1304 * be lying for the wider internet (e.g. _other_ queries were observed fine with
1305 * EDNS0 on these networks, post auth), i.e. let's just lower the level transaction's
1308 * This is reported as https://github.com/dns-violations/dns-violations/blob/master/2018/DVE-2018-0001.md
1311 t
->clamp_feature_level_nxdomain
= DNS_SERVER_FEATURE_LEVEL_UDP
;
1313 log_debug("Server returned error %s in EDNS0 mode, retrying transaction with reduced feature level %s (DVE-2018-0001 mitigation)",
1314 dns_rcode_to_string(DNS_PACKET_RCODE(p
)),
1315 dns_server_feature_level_to_string(t
->clamp_feature_level_nxdomain
));
1317 dns_transaction_retry(t
, false /* use the same server */);
1322 /* Report that we successfully received a valid packet with a good rcode after we initially got a bad
1323 * rcode and subsequently downgraded the protocol */
1325 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_SUCCESS
, DNS_RCODE_NXDOMAIN
) &&
1326 t
->clamp_feature_level_servfail
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
)
1327 dns_server_packet_rcode_downgrade(t
->server
, t
->clamp_feature_level_servfail
);
1329 /* Report that the OPT RR was missing */
1331 dns_server_packet_bad_opt(t
->server
, t
->current_feature_level
);
1333 /* Report that the server didn't copy our query DO bit from request to response */
1334 if (DNS_PACKET_DO(t
->sent
) && !DNS_PACKET_DO(t
->received
))
1335 dns_server_packet_do_off(t
->server
, t
->current_feature_level
);
1337 /* Report that we successfully received a packet. We keep track of the largest packet
1338 * size/fragment size we got. Which is useful for announcing the EDNS(0) packet size we can
1339 * receive to our server. */
1340 dns_server_packet_received(t
->server
, p
->ipproto
, t
->current_feature_level
, dns_packet_size_unfragmented(p
));
1343 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
1344 r
= dns_transaction_maybe_restart(t
);
1347 if (r
> 0) /* Transaction got restarted... */
1350 /* When dealing with protocols other than mDNS only consider responses with equivalent query section
1351 * to the request. For mDNS this check doesn't make sense, because the section 6 of RFC6762 states
1352 * that "Multicast DNS responses MUST NOT contain any questions in the Question Section". */
1353 if (t
->scope
->protocol
!= DNS_PROTOCOL_MDNS
) {
1354 r
= dns_packet_is_reply_for(p
, dns_transaction_key(t
));
1358 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1363 /* Install the answer as answer to the transaction. We ref the answer twice here: the main `answer`
1364 * field is later replaced by the DNSSEC validated subset. The 'answer_auxiliary' field carries the
1365 * original complete record set, including RRSIG and friends. We use this when passing data to
1366 * clients that ask for DNSSEC metadata. */
1367 dns_answer_unref(t
->answer
);
1368 t
->answer
= dns_answer_ref(p
->answer
);
1369 t
->answer_rcode
= DNS_PACKET_RCODE(p
);
1370 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
1371 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
, false);
1372 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_CONFIDENTIAL
, encrypted
);
1374 r
= dns_transaction_fix_rcode(t
);
1378 /* Block GC while starting requests for additional DNSSEC RRs */
1380 r
= dns_transaction_request_dnssec_keys(t
);
1383 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
1384 if (!dns_transaction_gc(t
))
1387 /* Requesting additional keys might have resulted in this transaction to fail, since the auxiliary
1388 * request failed for some reason. If so, we are not in pending state anymore, and we should exit
1390 if (t
->state
!= DNS_TRANSACTION_PENDING
)
1395 /* There are DNSSEC transactions pending now. Update the state accordingly. */
1396 t
->state
= DNS_TRANSACTION_VALIDATING
;
1397 dns_transaction_close_connection(t
, true);
1398 dns_transaction_stop_timeout(t
);
1402 dns_transaction_process_dnssec(t
);
1406 dns_transaction_complete_errno(t
, r
);
1409 static int on_dns_packet(sd_event_source
*s
, int fd
, uint32_t revents
, void *userdata
) {
1410 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1411 DnsTransaction
*t
= userdata
;
1417 r
= manager_recv(t
->scope
->manager
, fd
, DNS_PROTOCOL_DNS
, &p
);
1418 if (ERRNO_IS_DISCONNECT(r
)) {
1421 /* UDP connection failures get reported via ICMP and then are possibly delivered to us on the
1422 * next recvmsg(). Treat this like a lost packet. */
1424 log_debug_errno(r
, "Connection failure for DNS UDP packet: %m");
1425 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
1426 dns_server_packet_lost(t
->server
, IPPROTO_UDP
, t
->current_feature_level
);
1428 dns_transaction_close_connection(t
, /* use_graveyard = */ false);
1430 if (dns_transaction_limited_retry(t
)) /* Try a different server */
1433 dns_transaction_complete_errno(t
, r
);
1437 dns_transaction_complete_errno(t
, r
);
1441 /* Spurious wakeup without any data */
1444 r
= dns_packet_validate_reply(p
);
1446 log_debug_errno(r
, "Received invalid DNS packet as response, ignoring: %m");
1450 log_debug("Received inappropriate DNS packet as response, ignoring.");
1454 if (DNS_PACKET_ID(p
) != t
->id
) {
1455 log_debug("Received packet with incorrect transaction ID, ignoring.");
1459 dns_transaction_process_reply(t
, p
, false);
1463 static int dns_transaction_emit_udp(DnsTransaction
*t
) {
1468 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1470 r
= dns_transaction_pick_server(t
);
1474 if (manager_server_is_stub(t
->scope
->manager
, t
->server
))
1477 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_UDP
|| DNS_SERVER_FEATURE_LEVEL_IS_TLS(t
->current_feature_level
))
1478 return -EAGAIN
; /* Sorry, can't do UDP, try TCP! */
1480 if (!t
->bypass
&& !dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(dns_transaction_key(t
)->type
))
1483 if (r
> 0 || t
->dns_udp_fd
< 0) { /* Server changed, or no connection yet. */
1486 dns_transaction_close_connection(t
, true);
1488 /* Before we allocate a new UDP socket, let's process the graveyard a bit to free some fds */
1489 manager_socket_graveyard_process(t
->scope
->manager
);
1491 fd
= dns_scope_socket_udp(t
->scope
, t
->server
);
1495 r
= sd_event_add_io(t
->scope
->manager
->event
, &t
->dns_udp_event_source
, fd
, EPOLLIN
, on_dns_packet
, t
);
1501 (void) sd_event_source_set_description(t
->dns_udp_event_source
, "dns-transaction-udp");
1506 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
1511 dns_transaction_close_connection(t
, true);
1513 r
= dns_scope_emit_udp(t
->scope
, t
->dns_udp_fd
, t
->server
? t
->server
->family
: AF_UNSPEC
, t
->sent
);
1517 dns_transaction_reset_answer(t
);
1522 static int on_transaction_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1523 DnsTransaction
*t
= userdata
;
1528 if (t
->initial_jitter_scheduled
&& !t
->initial_jitter_elapsed
) {
1529 log_debug("Initial jitter phase for transaction %" PRIu16
" elapsed.", t
->id
);
1530 t
->initial_jitter_elapsed
= true;
1532 /* Timeout reached? Increase the timeout for the server used */
1533 switch (t
->scope
->protocol
) {
1535 case DNS_PROTOCOL_DNS
:
1537 dns_server_packet_lost(t
->server
, t
->stream
? IPPROTO_TCP
: IPPROTO_UDP
, t
->current_feature_level
);
1540 case DNS_PROTOCOL_LLMNR
:
1541 case DNS_PROTOCOL_MDNS
:
1542 dns_scope_packet_lost(t
->scope
, usec
- t
->start_usec
);
1546 assert_not_reached();
1549 log_debug("Timeout reached on transaction %" PRIu16
".", t
->id
);
1552 dns_transaction_retry(t
, /* next_server= */ true); /* try a different server, but given this means
1553 * packet loss, let's do so even if we already
1558 static usec_t
transaction_get_resend_timeout(DnsTransaction
*t
) {
1562 switch (t
->scope
->protocol
) {
1564 case DNS_PROTOCOL_DNS
:
1566 /* When we do TCP, grant a much longer timeout, as in this case there's no need for us to quickly
1567 * resend, as the kernel does that anyway for us, and we really don't want to interrupt it in that
1570 return TRANSACTION_TCP_TIMEOUT_USEC
;
1572 return DNS_TIMEOUT_USEC
;
1574 case DNS_PROTOCOL_MDNS
:
1575 assert(t
->n_attempts
> 0);
1577 return MDNS_PROBING_INTERVAL_USEC
;
1579 return (1 << (t
->n_attempts
- 1)) * USEC_PER_SEC
;
1581 case DNS_PROTOCOL_LLMNR
:
1582 return t
->scope
->resend_timeout
;
1585 assert_not_reached();
1589 static void dns_transaction_randomize_answer(DnsTransaction
*t
) {
1594 /* Randomizes the order of the answer array. This is done for all cached responses, so that we return
1595 * a different order each time. We do this only for DNS traffic, in order to do some minimal, crappy
1596 * load balancing. We don't do this for LLMNR or mDNS, since the order (preferring link-local
1597 * addresses, and such like) might have meaning there, and load balancing is pointless. */
1599 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1602 /* No point in randomizing, if there's just one RR */
1603 if (dns_answer_size(t
->answer
) <= 1)
1606 r
= dns_answer_reserve_or_clone(&t
->answer
, 0);
1607 if (r
< 0) /* If this fails, just don't randomize, this is non-essential stuff after all */
1608 return (void) log_debug_errno(r
, "Failed to clone answer record, not randomizing RR order of answer: %m");
1610 dns_answer_randomize(t
->answer
);
1613 static int dns_transaction_prepare(DnsTransaction
*t
, usec_t ts
) {
1618 /* Returns 0 if dns_transaction_complete() has been called. In that case the transaction and query
1619 * candidate objects may have been invalidated and must not be accessed. Returns 1 if the transaction
1620 * has been prepared. */
1622 dns_transaction_stop_timeout(t
);
1624 if (!dns_scope_network_good(t
->scope
)) {
1625 dns_transaction_complete(t
, DNS_TRANSACTION_NETWORK_DOWN
);
1629 if (t
->n_attempts
>= TRANSACTION_ATTEMPTS_MAX(t
->scope
->protocol
)) {
1630 DnsTransactionState result
;
1632 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
)
1633 /* If we didn't find anything on LLMNR, it's not an error, but a failure to resolve
1635 result
= DNS_TRANSACTION_NOT_FOUND
;
1637 result
= DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
;
1639 dns_transaction_complete(t
, result
);
1643 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& t
->tried_stream
) {
1644 /* If we already tried via a stream, then we don't
1645 * retry on LLMNR. See RFC 4795, Section 2.7. */
1646 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1653 dns_transaction_reset_answer(t
);
1654 dns_transaction_flush_dnssec_transactions(t
);
1656 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1657 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
&&
1658 !FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_TRUST_ANCHOR
)) {
1659 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, dns_transaction_key(t
), &t
->answer
);
1663 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1664 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1665 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
|SD_RESOLVED_CONFIDENTIAL
, true);
1666 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1670 if (dns_name_is_root(dns_resource_key_name(dns_transaction_key(t
))) &&
1671 dns_transaction_key(t
)->type
== DNS_TYPE_DS
) {
1673 /* Hmm, this is a request for the root DS? A DS RR doesn't exist in the root zone,
1674 * and if our trust anchor didn't know it either, this means we cannot do any DNSSEC
1677 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
1678 /* We are in downgrade mode. In this case, synthesize an unsigned empty
1679 * response, so that the any lookup depending on this one can continue
1680 * assuming there was no DS, and hence the root zone was unsigned. */
1682 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1683 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1684 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
, false);
1685 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_CONFIDENTIAL
, true);
1686 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1688 /* If we are not in downgrade mode, then fail the lookup, because we cannot
1689 * reasonably answer it. There might be DS RRs, but we don't know them, and
1690 * the DNS server won't tell them to us (and even if it would, we couldn't
1691 * validate and trust them. */
1692 dns_transaction_complete(t
, DNS_TRANSACTION_NO_TRUST_ANCHOR
);
1698 /* Check the zone. */
1699 if (!FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_ZONE
)) {
1700 r
= dns_zone_lookup(&t
->scope
->zone
, dns_transaction_key(t
), dns_scope_ifindex(t
->scope
), &t
->answer
, NULL
, NULL
);
1704 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1705 t
->answer_source
= DNS_TRANSACTION_ZONE
;
1706 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
|SD_RESOLVED_CONFIDENTIAL
, true);
1707 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1712 /* Check the cache. */
1713 if (!FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_CACHE
)) {
1715 /* Before trying the cache, let's make sure we figured out a server to use. Should this cause
1716 * a change of server this might flush the cache. */
1717 (void) dns_scope_get_dns_server(t
->scope
);
1719 /* Let's then prune all outdated entries */
1720 dns_cache_prune(&t
->scope
->cache
);
1722 r
= dns_cache_lookup(
1724 dns_transaction_key(t
),
1729 &t
->answer_query_flags
,
1730 &t
->answer_dnssec_result
);
1734 dns_transaction_randomize_answer(t
);
1736 if (t
->bypass
&& t
->scope
->protocol
== DNS_PROTOCOL_DNS
&& !t
->received
)
1737 /* When bypass mode is on, do not use cached data unless it came with a full
1739 dns_transaction_reset_answer(t
);
1741 t
->answer_source
= DNS_TRANSACTION_CACHE
;
1742 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
1743 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1745 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
1751 if (FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_NETWORK
)) {
1752 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SOURCE
);
1759 static int dns_transaction_make_packet_mdns(DnsTransaction
*t
) {
1760 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1761 bool add_known_answers
= false;
1762 DnsResourceKey
*tkey
;
1763 _cleanup_set_free_ Set
*keys
= NULL
;
1765 unsigned nscount
= 0;
1770 assert(t
->scope
->protocol
== DNS_PROTOCOL_MDNS
);
1772 /* Discard any previously prepared packet, so we can start over and coalesce again */
1773 t
->sent
= dns_packet_unref(t
->sent
);
1775 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, false);
1779 r
= dns_packet_append_key(p
, dns_transaction_key(t
), 0, NULL
);
1785 if (dns_key_is_shared(dns_transaction_key(t
)))
1786 add_known_answers
= true;
1788 if (dns_transaction_key(t
)->type
== DNS_TYPE_ANY
) {
1789 r
= set_ensure_put(&keys
, &dns_resource_key_hash_ops
, dns_transaction_key(t
));
1795 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1796 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1797 * in our current scope, and see whether their timing constraints allow them to be sent.
1800 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1802 LIST_FOREACH(transactions_by_scope
, other
, t
->scope
->transactions
) {
1804 /* Skip ourselves */
1808 if (other
->state
!= DNS_TRANSACTION_PENDING
)
1811 if (other
->next_attempt_after
> ts
)
1814 if (qdcount
>= UINT16_MAX
)
1817 r
= dns_packet_append_key(p
, dns_transaction_key(other
), 0, NULL
);
1820 * If we can't stuff more questions into the packet, just give up.
1821 * One of the 'other' transactions will fire later and take care of the rest.
1829 r
= dns_transaction_prepare(other
, ts
);
1833 ts
+= transaction_get_resend_timeout(other
);
1835 r
= sd_event_add_time(
1836 other
->scope
->manager
->event
,
1837 &other
->timeout_event_source
,
1838 clock_boottime_or_monotonic(),
1840 on_transaction_timeout
, other
);
1844 (void) sd_event_source_set_description(other
->timeout_event_source
, "dns-transaction-timeout");
1846 other
->state
= DNS_TRANSACTION_PENDING
;
1847 other
->next_attempt_after
= ts
;
1851 if (dns_key_is_shared(dns_transaction_key(other
)))
1852 add_known_answers
= true;
1854 if (dns_transaction_key(other
)->type
== DNS_TYPE_ANY
) {
1855 r
= set_ensure_put(&keys
, &dns_resource_key_hash_ops
, dns_transaction_key(other
));
1861 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(qdcount
);
1863 /* Append known answer section if we're asking for any shared record */
1864 if (add_known_answers
) {
1865 r
= dns_cache_export_shared_to_packet(&t
->scope
->cache
, p
);
1870 SET_FOREACH(tkey
, keys
) {
1871 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
;
1874 r
= dns_zone_lookup(&t
->scope
->zone
, tkey
, t
->scope
->link
->ifindex
, &answer
, NULL
, &tentative
);
1878 r
= dns_packet_append_answer(p
, answer
, &nscount
);
1882 DNS_PACKET_HEADER(p
)->nscount
= htobe16(nscount
);
1884 t
->sent
= TAKE_PTR(p
);
1889 static int dns_transaction_make_packet(DnsTransaction
*t
) {
1890 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1895 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)
1896 return dns_transaction_make_packet_mdns(t
);
1901 if (t
->bypass
&& t
->bypass
->protocol
== t
->scope
->protocol
) {
1902 /* If bypass logic is enabled and the protocol if the original packet and our scope match,
1903 * take the original packet, copy it, and patch in our new ID */
1904 r
= dns_packet_dup(&p
, t
->bypass
);
1908 r
= dns_packet_new_query(
1909 &p
, t
->scope
->protocol
,
1910 /* min_alloc_dsize = */ 0,
1911 /* dnssec_cd = */ !FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_VALIDATE
) &&
1912 t
->scope
->dnssec_mode
!= DNSSEC_NO
);
1916 r
= dns_packet_append_key(p
, dns_transaction_key(t
), 0, NULL
);
1920 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
1923 DNS_PACKET_HEADER(p
)->id
= t
->id
;
1925 t
->sent
= TAKE_PTR(p
);
1929 int dns_transaction_go(DnsTransaction
*t
) {
1932 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1936 /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has
1937 * finished now. In the latter case, the transaction and query candidate objects must not be accessed.
1940 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1942 r
= dns_transaction_prepare(t
, ts
);
1946 log_debug("Firing %s transaction %" PRIu16
" for <%s> scope %s on %s/%s (validate=%s).",
1947 t
->bypass
? "bypass" : "regular",
1949 dns_resource_key_to_string(dns_transaction_key(t
), key_str
, sizeof key_str
),
1950 dns_protocol_to_string(t
->scope
->protocol
),
1951 t
->scope
->link
? t
->scope
->link
->ifname
: "*",
1952 af_to_name_short(t
->scope
->family
),
1953 yes_no(!FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_VALIDATE
)));
1955 if (!t
->initial_jitter_scheduled
&&
1956 IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_LLMNR
, DNS_PROTOCOL_MDNS
)) {
1957 usec_t jitter
, accuracy
;
1959 /* RFC 4795 Section 2.7 suggests all queries should be delayed by a random time from 0 to
1960 * JITTER_INTERVAL. */
1962 t
->initial_jitter_scheduled
= true;
1964 switch (t
->scope
->protocol
) {
1966 case DNS_PROTOCOL_LLMNR
:
1967 jitter
= random_u64_range(LLMNR_JITTER_INTERVAL_USEC
);
1968 accuracy
= LLMNR_JITTER_INTERVAL_USEC
;
1971 case DNS_PROTOCOL_MDNS
:
1972 jitter
= usec_add(random_u64_range(MDNS_JITTER_RANGE_USEC
), MDNS_JITTER_MIN_USEC
);
1973 accuracy
= MDNS_JITTER_RANGE_USEC
;
1976 assert_not_reached();
1979 assert(!t
->timeout_event_source
);
1981 r
= sd_event_add_time_relative(
1982 t
->scope
->manager
->event
,
1983 &t
->timeout_event_source
,
1984 clock_boottime_or_monotonic(),
1986 on_transaction_timeout
, t
);
1990 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1993 t
->next_attempt_after
= ts
;
1994 t
->state
= DNS_TRANSACTION_PENDING
;
1996 log_debug("Delaying %s transaction %" PRIu16
" for " USEC_FMT
"us.",
1997 dns_protocol_to_string(t
->scope
->protocol
),
2003 /* Otherwise, we need to ask the network */
2004 r
= dns_transaction_make_packet(t
);
2008 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&&
2009 (dns_name_endswith(dns_resource_key_name(dns_transaction_key(t
)), "in-addr.arpa") > 0 ||
2010 dns_name_endswith(dns_resource_key_name(dns_transaction_key(t
)), "ip6.arpa") > 0)) {
2012 /* RFC 4795, Section 2.4. says reverse lookups shall
2013 * always be made via TCP on LLMNR */
2014 r
= dns_transaction_emit_tcp(t
);
2016 /* Try via UDP, and if that fails due to large size or lack of
2017 * support try via TCP */
2018 r
= dns_transaction_emit_udp(t
);
2020 log_debug("Sending query via TCP since it is too large.");
2021 else if (r
== -EAGAIN
)
2022 log_debug("Sending query via TCP since UDP isn't supported or DNS-over-TLS is selected.");
2023 if (IN_SET(r
, -EMSGSIZE
, -EAGAIN
))
2024 r
= dns_transaction_emit_tcp(t
);
2027 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
2030 /* One of our own stub listeners */
2031 log_debug_errno(r
, "Detected that specified DNS server is our own extra listener, switching DNS servers.");
2033 dns_scope_next_dns_server(t
->scope
, t
->server
);
2035 if (dns_scope_get_dns_server(t
->scope
) == t
->server
) {
2036 log_debug_errno(r
, "Still pointing to extra listener after switching DNS servers, refusing operation.");
2037 dns_transaction_complete(t
, DNS_TRANSACTION_STUB_LOOP
);
2041 return dns_transaction_go(t
);
2044 /* No servers to send this to? */
2045 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
2048 if (r
== -EOPNOTSUPP
) {
2049 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
2050 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
2053 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& ERRNO_IS_DISCONNECT(r
)) {
2054 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
2055 * answer this request with this protocol. */
2056 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
2060 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
2063 /* Couldn't send? Try immediately again, with a new server */
2064 dns_scope_next_dns_server(t
->scope
, t
->server
);
2066 return dns_transaction_go(t
);
2069 ts
+= transaction_get_resend_timeout(t
);
2071 r
= sd_event_add_time(
2072 t
->scope
->manager
->event
,
2073 &t
->timeout_event_source
,
2074 clock_boottime_or_monotonic(),
2076 on_transaction_timeout
, t
);
2080 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
2082 t
->state
= DNS_TRANSACTION_PENDING
;
2083 t
->next_attempt_after
= ts
;
2088 static int dns_transaction_find_cyclic(DnsTransaction
*t
, DnsTransaction
*aux
) {
2095 /* Try to find cyclic dependencies between transaction objects */
2100 SET_FOREACH(n
, aux
->dnssec_transactions
) {
2101 r
= dns_transaction_find_cyclic(t
, n
);
2109 static int dns_transaction_add_dnssec_transaction(DnsTransaction
*t
, DnsResourceKey
*key
, DnsTransaction
**ret
) {
2110 _cleanup_(dns_transaction_gcp
) DnsTransaction
*aux
= NULL
;
2117 aux
= dns_scope_find_transaction(t
->scope
, key
, t
->query_flags
);
2119 r
= dns_transaction_new(&aux
, t
->scope
, key
, NULL
, t
->query_flags
);
2123 if (set_contains(t
->dnssec_transactions
, aux
)) {
2128 r
= dns_transaction_find_cyclic(t
, aux
);
2132 char s
[DNS_RESOURCE_KEY_STRING_MAX
], saux
[DNS_RESOURCE_KEY_STRING_MAX
];
2134 return log_debug_errno(SYNTHETIC_ERRNO(ELOOP
),
2135 "Potential cyclic dependency, refusing to add transaction %" PRIu16
" (%s) as dependency for %" PRIu16
" (%s).",
2137 dns_resource_key_to_string(dns_transaction_key(t
), s
, sizeof s
),
2139 dns_resource_key_to_string(dns_transaction_key(aux
), saux
, sizeof saux
));
2143 r
= set_ensure_allocated(&aux
->notify_transactions_done
, NULL
);
2147 r
= set_ensure_put(&t
->dnssec_transactions
, NULL
, aux
);
2151 r
= set_ensure_put(&aux
->notify_transactions
, NULL
, t
);
2153 (void) set_remove(t
->dnssec_transactions
, aux
);
2157 *ret
= TAKE_PTR(aux
);
2161 static int dns_transaction_request_dnssec_rr(DnsTransaction
*t
, DnsResourceKey
*key
) {
2162 _cleanup_(dns_answer_unrefp
) DnsAnswer
*a
= NULL
;
2163 DnsTransaction
*aux
;
2169 /* Try to get the data from the trust anchor */
2170 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, key
, &a
);
2174 r
= dns_answer_extend(&t
->validated_keys
, a
);
2181 /* This didn't work, ask for it via the network/cache then. */
2182 r
= dns_transaction_add_dnssec_transaction(t
, key
, &aux
);
2183 if (r
== -ELOOP
) /* This would result in a cyclic dependency */
2188 if (aux
->state
== DNS_TRANSACTION_NULL
) {
2189 r
= dns_transaction_go(aux
);
2197 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction
*t
, const char *name
) {
2202 /* Check whether the specified name is in the NTA
2203 * database, either in the global one, or the link-local
2206 r
= dns_trust_anchor_lookup_negative(&t
->scope
->manager
->trust_anchor
, name
);
2210 if (!t
->scope
->link
)
2213 return link_negative_trust_anchor_lookup(t
->scope
->link
, name
);
2216 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction
*t
) {
2221 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
2222 * RRs to prove it */
2224 r
= dns_transaction_has_positive_answer(t
, NULL
);
2230 /* Is this key explicitly listed as a negative trust anchor?
2231 * If so, it's nothing we need to care about */
2232 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(dns_transaction_key(t
)));
2238 /* The answer does not contain any RRs that match to the
2239 * question. If so, let's see if there are any NSEC/NSEC3 RRs
2240 * included. If not, the answer is unsigned. */
2242 return !dns_answer_contains_nsec_or_nsec3(t
->answer
);
2245 static int dns_transaction_is_primary_response(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2251 /* Check if the specified RR is the "primary" response,
2252 * i.e. either matches the question precisely or is a
2253 * CNAME/DNAME for it. */
2255 r
= dns_resource_key_match_rr(dns_transaction_key(t
), rr
, NULL
);
2259 return dns_resource_key_match_cname_or_dname(dns_transaction_key(t
), rr
->key
, NULL
);
2262 static bool dns_transaction_dnssec_supported(DnsTransaction
*t
) {
2265 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
2266 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
2268 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
2271 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
2272 * be supported, hence return true. */
2276 /* Note that we do not check the feature level actually used for the transaction but instead the feature level
2277 * the server is known to support currently, as the transaction feature level might be lower than what the
2278 * server actually supports, since we might have downgraded this transaction's feature level because we got a
2279 * SERVFAIL earlier and wanted to check whether downgrading fixes it. */
2281 return dns_server_dnssec_supported(t
->server
);
2284 static bool dns_transaction_dnssec_supported_full(DnsTransaction
*t
) {
2289 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
2291 if (!dns_transaction_dnssec_supported(t
))
2294 SET_FOREACH(dt
, t
->dnssec_transactions
)
2295 if (!dns_transaction_dnssec_supported(dt
))
2301 int dns_transaction_request_dnssec_keys(DnsTransaction
*t
) {
2302 DnsResourceRecord
*rr
;
2309 * Retrieve all auxiliary RRs for the answer we got, so that
2310 * we can verify signatures or prove that RRs are rightfully
2311 * unsigned. Specifically:
2313 * - For RRSIG we get the matching DNSKEY
2314 * - For DNSKEY we get the matching DS
2315 * - For unsigned SOA/NS we get the matching DS
2316 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
2317 * - For other unsigned RRs we get the matching SOA RR
2318 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
2319 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
2320 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
2323 if (FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_VALIDATE
) || t
->scope
->dnssec_mode
== DNSSEC_NO
)
2325 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
2326 return 0; /* We only need to validate stuff from the network */
2327 if (!dns_transaction_dnssec_supported(t
))
2328 return 0; /* If we can't do DNSSEC anyway there's no point in getting the auxiliary RRs */
2330 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2332 if (dns_type_is_pseudo(rr
->key
->type
))
2335 /* If this RR is in the negative trust anchor, we don't need to validate it. */
2336 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2342 switch (rr
->key
->type
) {
2344 case DNS_TYPE_RRSIG
: {
2345 /* For each RRSIG we request the matching DNSKEY */
2346 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*dnskey
= NULL
;
2348 /* If this RRSIG is about a DNSKEY RR and the
2349 * signer is the same as the owner, then we
2350 * already have the DNSKEY, and we don't have
2351 * to look for more. */
2352 if (rr
->rrsig
.type_covered
== DNS_TYPE_DNSKEY
) {
2353 r
= dns_name_equal(rr
->rrsig
.signer
, dns_resource_key_name(rr
->key
));
2360 /* If the signer is not a parent of our
2361 * original query, then this is about an
2362 * auxiliary RRset, but not anything we asked
2363 * for. In this case we aren't interested,
2364 * because we don't want to request additional
2365 * RRs for stuff we didn't really ask for, and
2366 * also to avoid request loops, where
2367 * additional RRs from one transaction result
2368 * in another transaction whose additional RRs
2369 * point back to the original transaction, and
2371 r
= dns_name_endswith(dns_resource_key_name(dns_transaction_key(t
)), rr
->rrsig
.signer
);
2377 dnskey
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DNSKEY
, rr
->rrsig
.signer
);
2381 log_debug("Requesting DNSKEY to validate transaction %" PRIu16
" (%s, RRSIG with key tag: %" PRIu16
").",
2382 t
->id
, dns_resource_key_name(rr
->key
), rr
->rrsig
.key_tag
);
2383 r
= dns_transaction_request_dnssec_rr(t
, dnskey
);
2389 case DNS_TYPE_DNSKEY
: {
2390 /* For each DNSKEY we request the matching DS */
2391 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
2393 /* If the DNSKEY we are looking at is not for
2394 * zone we are interested in, nor any of its
2395 * parents, we aren't interested, and don't
2396 * request it. After all, we don't want to end
2397 * up in request loops, and want to keep
2398 * additional traffic down. */
2400 r
= dns_name_endswith(dns_resource_key_name(dns_transaction_key(t
)), dns_resource_key_name(rr
->key
));
2406 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
2410 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, DNSKEY with key tag: %" PRIu16
").",
2411 t
->id
, dns_resource_key_name(rr
->key
), dnssec_keytag(rr
, false));
2412 r
= dns_transaction_request_dnssec_rr(t
, ds
);
2421 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
2423 /* For an unsigned SOA or NS, try to acquire
2424 * the matching DS RR, as we are at a zone cut
2425 * then, and whether a DS exists tells us
2426 * whether the zone is signed. Do so only if
2427 * this RR matches our original question,
2430 r
= dns_resource_key_match_rr(dns_transaction_key(t
), rr
, NULL
);
2434 /* Hmm, so this SOA RR doesn't match our original question. In this case, maybe this is
2435 * a negative reply, and we need the SOA RR's TTL in order to cache a negative entry?
2436 * If so, we need to validate it, too. */
2438 r
= dns_answer_match_key(t
->answer
, dns_transaction_key(t
), NULL
);
2441 if (r
> 0) /* positive reply, we won't need the SOA and hence don't need to validate
2445 /* Only bother with this if the SOA/NS RR we are looking at is actually a parent of
2446 * what we are looking for, otherwise there's no value in it for us. */
2447 r
= dns_name_endswith(dns_resource_key_name(dns_transaction_key(t
)), dns_resource_key_name(rr
->key
));
2454 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2460 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
2464 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned SOA/NS RRset).",
2465 t
->id
, dns_resource_key_name(rr
->key
));
2466 r
= dns_transaction_request_dnssec_rr(t
, ds
);
2474 case DNS_TYPE_CNAME
:
2475 case DNS_TYPE_DNAME
: {
2476 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2479 /* CNAMEs and DNAMEs cannot be located at a
2480 * zone apex, hence ask for the parent SOA for
2481 * unsigned CNAME/DNAME RRs, maybe that's the
2482 * apex. But do all that only if this is
2483 * actually a response to our original
2486 * Similar for DS RRs, which are signed when
2487 * the parent SOA is signed. */
2489 r
= dns_transaction_is_primary_response(t
, rr
);
2495 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2501 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2507 name
= dns_resource_key_name(rr
->key
);
2508 r
= dns_name_parent(&name
);
2514 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, name
);
2518 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned CNAME/DNAME/DS RRset).",
2519 t
->id
, dns_resource_key_name(rr
->key
));
2520 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2528 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2530 /* For other unsigned RRsets (including
2531 * NSEC/NSEC3!), look for proof the zone is
2532 * unsigned, by requesting the SOA RR of the
2533 * zone. However, do so only if they are
2534 * directly relevant to our original
2537 r
= dns_transaction_is_primary_response(t
, rr
);
2543 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2549 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, dns_resource_key_name(rr
->key
));
2553 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned non-SOA/NS RRset <%s>).",
2554 t
->id
, dns_resource_key_name(rr
->key
), dns_resource_record_to_string(rr
));
2555 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2562 /* Above, we requested everything necessary to validate what
2563 * we got. Now, let's request what we need to validate what we
2566 r
= dns_transaction_has_unsigned_negative_answer(t
);
2573 name
= dns_resource_key_name(dns_transaction_key(t
));
2575 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2576 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2577 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2578 * though they have further children. If this was a DS request, then it's signed when the parent zone
2579 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2580 * to see if that is signed. */
2582 if (dns_transaction_key(t
)->type
== DNS_TYPE_DS
) {
2583 r
= dns_name_parent(&name
);
2585 type
= DNS_TYPE_SOA
;
2586 log_debug("Requesting parent SOA (→ %s) to validate transaction %" PRIu16
" (%s, unsigned empty DS response).",
2587 name
, t
->id
, dns_resource_key_name(dns_transaction_key(t
)));
2591 } else if (IN_SET(dns_transaction_key(t
)->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
)) {
2594 log_debug("Requesting DS (→ %s) to validate transaction %" PRIu16
" (%s, unsigned empty SOA/NS response).",
2598 type
= DNS_TYPE_SOA
;
2599 log_debug("Requesting SOA (→ %s) to validate transaction %" PRIu16
" (%s, unsigned empty non-SOA/NS/DS response).",
2604 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2606 soa
= dns_resource_key_new(dns_transaction_key(t
)->class, type
, name
);
2610 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2616 return dns_transaction_dnssec_is_live(t
);
2619 void dns_transaction_notify(DnsTransaction
*t
, DnsTransaction
*source
) {
2623 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2624 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2625 the state is VALIDATING however, we should check if we are complete now. */
2627 if (t
->state
== DNS_TRANSACTION_VALIDATING
)
2628 dns_transaction_process_dnssec(t
);
2631 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction
*t
) {
2632 DnsAnswerItem
*item
;
2637 /* Add all DNSKEY RRs from the answer that are validated by DS
2638 * RRs from the list of validated keys to the list of
2639 * validated keys. */
2641 DNS_ANSWER_FOREACH_ITEM(item
, t
->answer
) {
2643 r
= dnssec_verify_dnskey_by_ds_search(item
->rr
, t
->validated_keys
);
2649 /* If so, the DNSKEY is validated too. */
2650 r
= dns_answer_add_extend(&t
->validated_keys
, item
->rr
, item
->ifindex
, item
->flags
|DNS_ANSWER_AUTHENTICATED
, item
->rrsig
);
2658 static int dns_transaction_requires_rrsig(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2664 /* Checks if the RR we are looking for must be signed with an
2665 * RRSIG. This is used for positive responses. */
2667 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2670 if (dns_type_is_pseudo(rr
->key
->type
))
2673 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2679 switch (rr
->key
->type
) {
2681 case DNS_TYPE_RRSIG
:
2682 /* RRSIGs are the signatures themselves, they need no signing. */
2689 /* For SOA or NS RRs we look for a matching DS transaction */
2691 SET_FOREACH(dt
, t
->dnssec_transactions
) {
2693 if (dns_transaction_key(dt
)->class != rr
->key
->class)
2695 if (dns_transaction_key(dt
)->type
!= DNS_TYPE_DS
)
2698 r
= dns_name_equal(dns_resource_key_name(dns_transaction_key(dt
)), dns_resource_key_name(rr
->key
));
2704 /* We found a DS transactions for the SOA/NS
2705 * RRs we are looking at. If it discovered signed DS
2706 * RRs, then we need to be signed, too. */
2708 if (!FLAGS_SET(dt
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
))
2711 return dns_answer_match_key(dt
->answer
, dns_transaction_key(dt
), NULL
);
2714 /* We found nothing that proves this is safe to leave
2715 * this unauthenticated, hence ask inist on
2716 * authentication. */
2721 case DNS_TYPE_CNAME
:
2722 case DNS_TYPE_DNAME
: {
2723 const char *parent
= NULL
;
2727 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2729 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2732 SET_FOREACH(dt
, t
->dnssec_transactions
) {
2734 if (dns_transaction_key(dt
)->class != rr
->key
->class)
2736 if (dns_transaction_key(dt
)->type
!= DNS_TYPE_SOA
)
2740 parent
= dns_resource_key_name(rr
->key
);
2741 r
= dns_name_parent(&parent
);
2745 if (rr
->key
->type
== DNS_TYPE_DS
)
2748 /* A CNAME/DNAME without a parent? That's sooo weird. */
2749 return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG
),
2750 "Transaction %" PRIu16
" claims CNAME/DNAME at root. Refusing.", t
->id
);
2754 r
= dns_name_equal(dns_resource_key_name(dns_transaction_key(dt
)), parent
);
2760 return FLAGS_SET(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
);
2769 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2771 SET_FOREACH(dt
, t
->dnssec_transactions
) {
2773 if (dns_transaction_key(dt
)->class != rr
->key
->class)
2775 if (dns_transaction_key(dt
)->type
!= DNS_TYPE_SOA
)
2778 r
= dns_name_equal(dns_resource_key_name(dns_transaction_key(dt
)), dns_resource_key_name(rr
->key
));
2784 /* We found the transaction that was supposed to find the SOA RR for us. It was
2785 * successful, but found no RR for us. This means we are not at a zone cut. In this
2786 * case, we require authentication if the SOA lookup was authenticated too. */
2787 return FLAGS_SET(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
);
2794 static int dns_transaction_in_private_tld(DnsTransaction
*t
, const DnsResourceKey
*key
) {
2799 /* If DNSSEC downgrade mode is on, checks whether the
2800 * specified RR is one level below a TLD we have proven not to
2801 * exist. In such a case we assume that this is a private
2802 * domain, and permit it.
2804 * This detects cases like the Fritz!Box router networks. Each
2805 * Fritz!Box router serves a private "fritz.box" zone, in the
2806 * non-existing TLD "box". Requests for the "fritz.box" domain
2807 * are served by the router itself, while requests for the
2808 * "box" domain will result in NXDOMAIN.
2810 * Note that this logic is unable to detect cases where a
2811 * router serves a private DNS zone directly under
2812 * non-existing TLD. In such a case we cannot detect whether
2813 * the TLD is supposed to exist or not, as all requests we
2814 * make for it will be answered by the router's zone, and not
2815 * by the root zone. */
2819 if (t
->scope
->dnssec_mode
!= DNSSEC_ALLOW_DOWNGRADE
)
2820 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2822 tld
= dns_resource_key_name(key
);
2823 r
= dns_name_parent(&tld
);
2827 return false; /* Already the root domain */
2829 if (!dns_name_is_single_label(tld
))
2832 SET_FOREACH(dt
, t
->dnssec_transactions
) {
2834 if (dns_transaction_key(dt
)->class != key
->class)
2837 r
= dns_name_equal(dns_resource_key_name(dns_transaction_key(dt
)), tld
);
2843 /* We found an auxiliary lookup we did for the TLD. If
2844 * that returned with NXDOMAIN, we know the TLD didn't
2845 * exist, and hence this might be a private zone. */
2847 return dt
->answer_rcode
== DNS_RCODE_NXDOMAIN
;
2853 static int dns_transaction_requires_nsec(DnsTransaction
*t
) {
2854 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2862 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2863 * this negative reply */
2865 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2868 if (dns_type_is_pseudo(dns_transaction_key(t
)->type
))
2871 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(dns_transaction_key(t
)));
2877 r
= dns_transaction_in_private_tld(t
, dns_transaction_key(t
));
2881 /* The lookup is from a TLD that is proven not to
2882 * exist, and we are in downgrade mode, hence ignore
2883 * that fact that we didn't get any NSEC RRs. */
2885 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2886 dns_resource_key_to_string(dns_transaction_key(t
), key_str
, sizeof key_str
));
2890 name
= dns_resource_key_name(dns_transaction_key(t
));
2892 if (dns_transaction_key(t
)->type
== DNS_TYPE_DS
) {
2894 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2895 * hence check the parent SOA in this case. */
2897 r
= dns_name_parent(&name
);
2903 type
= DNS_TYPE_SOA
;
2905 } else if (IN_SET(dns_transaction_key(t
)->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
))
2906 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2909 /* For all other negative replies, check for the SOA lookup */
2910 type
= DNS_TYPE_SOA
;
2912 /* For all other RRs we check the SOA on the same level to see
2913 * if it's signed. */
2915 SET_FOREACH(dt
, t
->dnssec_transactions
) {
2917 if (dns_transaction_key(dt
)->class != dns_transaction_key(t
)->class)
2919 if (dns_transaction_key(dt
)->type
!= type
)
2922 r
= dns_name_equal(dns_resource_key_name(dns_transaction_key(dt
)), name
);
2928 return FLAGS_SET(dt
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
);
2931 /* If in doubt, require NSEC/NSEC3 */
2935 static int dns_transaction_dnskey_authenticated(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2936 DnsResourceRecord
*rrsig
;
2940 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2941 * the specified RRset is authenticated (i.e. has a matching
2944 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2950 DNS_ANSWER_FOREACH(rrsig
, t
->answer
) {
2953 r
= dnssec_key_match_rrsig(rr
->key
, rrsig
);
2959 SET_FOREACH(dt
, t
->dnssec_transactions
) {
2961 if (dns_transaction_key(dt
)->class != rr
->key
->class)
2964 if (dns_transaction_key(dt
)->type
== DNS_TYPE_DNSKEY
) {
2966 r
= dns_name_equal(dns_resource_key_name(dns_transaction_key(dt
)), rrsig
->rrsig
.signer
);
2972 /* OK, we found an auxiliary DNSKEY lookup. If that lookup is authenticated,
2975 if (FLAGS_SET(dt
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
))
2980 } else if (dns_transaction_key(dt
)->type
== DNS_TYPE_DS
) {
2982 r
= dns_name_equal(dns_resource_key_name(dns_transaction_key(dt
)), rrsig
->rrsig
.signer
);
2988 /* OK, we found an auxiliary DS lookup. If that lookup is authenticated and
2989 * non-zero, we won! */
2991 if (!FLAGS_SET(dt
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
))
2994 return dns_answer_match_key(dt
->answer
, dns_transaction_key(dt
), NULL
);
2999 return found
? false : -ENXIO
;
3002 static int dns_transaction_known_signed(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
3006 /* We know that the root domain is signed, hence if it appears
3007 * not to be signed, there's a problem with the DNS server */
3009 return rr
->key
->class == DNS_CLASS_IN
&&
3010 dns_name_is_root(dns_resource_key_name(rr
->key
));
3013 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction
*t
) {
3014 DnsResourceRecord
*rr
;
3019 /* Maybe warn the user that we encountered a revoked DNSKEY
3020 * for a key from our trust anchor. Note that we don't care
3021 * whether the DNSKEY can be authenticated or not. It's
3022 * sufficient if it is self-signed. */
3024 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
3025 r
= dns_trust_anchor_check_revoked(&t
->scope
->manager
->trust_anchor
, rr
, t
->answer
);
3033 static int dns_transaction_invalidate_revoked_keys(DnsTransaction
*t
) {
3039 /* Removes all DNSKEY/DS objects from t->validated_keys that
3040 * our trust anchors database considers revoked. */
3043 DnsResourceRecord
*rr
;
3047 DNS_ANSWER_FOREACH(rr
, t
->validated_keys
) {
3048 r
= dns_trust_anchor_is_revoked(&t
->scope
->manager
->trust_anchor
, rr
);
3052 r
= dns_answer_remove_by_rr(&t
->validated_keys
, rr
);
3066 static int dns_transaction_copy_validated(DnsTransaction
*t
) {
3072 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
3074 SET_FOREACH(dt
, t
->dnssec_transactions
) {
3076 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
3079 if (!FLAGS_SET(dt
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
))
3082 r
= dns_answer_extend(&t
->validated_keys
, dt
->answer
);
3091 DNSSEC_PHASE_DNSKEY
, /* Phase #1, only validate DNSKEYs */
3092 DNSSEC_PHASE_NSEC
, /* Phase #2, only validate NSEC+NSEC3 */
3093 DNSSEC_PHASE_ALL
, /* Phase #3, validate everything else */
3096 static int dnssec_validate_records(
3100 DnsAnswer
**validated
) {
3102 DnsResourceRecord
*rr
;
3105 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
3107 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
3108 DnsResourceRecord
*rrsig
= NULL
;
3109 DnssecResult result
;
3111 switch (rr
->key
->type
) {
3112 case DNS_TYPE_RRSIG
:
3115 case DNS_TYPE_DNSKEY
:
3116 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
3117 if (phase
== DNSSEC_PHASE_NSEC
)
3122 case DNS_TYPE_NSEC3
:
3125 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
3126 if (phase
== DNSSEC_PHASE_DNSKEY
)
3131 /* We validate all other RRs only in the ALL phases */
3132 if (phase
!= DNSSEC_PHASE_ALL
)
3136 r
= dnssec_verify_rrset_search(
3146 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr
)), dnssec_result_to_string(result
));
3148 if (result
== DNSSEC_VALIDATED
) {
3151 if (rr
->key
->type
== DNS_TYPE_DNSKEY
) {
3152 /* If we just validated a DNSKEY RRset, then let's add these keys to
3153 * the set of validated keys for this transaction. */
3155 r
= dns_answer_copy_by_key(&t
->validated_keys
, t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
, rrsig
);
3159 /* Some of the DNSKEYs we just added might already have been revoked,
3160 * remove them again in that case. */
3161 r
= dns_transaction_invalidate_revoked_keys(t
);
3166 /* Add the validated RRset to the new list of validated RRsets, and remove it from
3167 * the unvalidated RRsets. We mark the RRset as authenticated and cacheable. */
3168 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
, rrsig
);
3172 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_SECURE
, rr
->key
);
3174 /* Exit the loop, we dropped something from the answer, start from the beginning */
3178 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
3179 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
3180 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
3181 if (phase
!= DNSSEC_PHASE_ALL
)
3184 if (result
== DNSSEC_VALIDATED_WILDCARD
) {
3185 bool authenticated
= false;
3190 /* This RRset validated, but as a wildcard. This means we need
3191 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists. */
3193 /* First step, determine the source of synthesis */
3194 r
= dns_resource_record_source(rrsig
, &source
);
3198 r
= dnssec_test_positive_wildcard(*validated
,
3199 dns_resource_key_name(rr
->key
),
3201 rrsig
->rrsig
.signer
,
3204 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
3206 result
= DNSSEC_INVALID
;
3208 r
= dns_answer_move_by_key(
3212 authenticated
? (DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
) : 0,
3217 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, rr
->key
);
3219 /* Exit the loop, we dropped something from the answer, start from the beginning */
3224 if (result
== DNSSEC_NO_SIGNATURE
) {
3225 r
= dns_transaction_requires_rrsig(t
, rr
);
3229 /* Data does not require signing. In that case, just copy it over,
3230 * but remember that this is by no means authenticated. */
3231 r
= dns_answer_move_by_key(
3240 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
3244 r
= dns_transaction_known_signed(t
, rr
);
3248 /* This is an RR we know has to be signed. If it isn't this means
3249 * the server is not attaching RRSIGs, hence complain. */
3251 dns_server_packet_rrsig_missing(t
->server
, t
->current_feature_level
);
3253 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
3255 /* Downgrading is OK? If so, just consider the information unsigned */
3257 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0, NULL
);
3261 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
3265 /* Otherwise, fail */
3266 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
3270 r
= dns_transaction_in_private_tld(t
, rr
->key
);
3274 char s
[DNS_RESOURCE_KEY_STRING_MAX
];
3276 /* The data is from a TLD that is proven not to exist, and we are in downgrade
3277 * mode, hence ignore the fact that this was not signed. */
3279 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
3280 dns_resource_key_to_string(rr
->key
, s
, sizeof s
));
3282 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0, NULL
);
3286 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
3293 DNSSEC_SIGNATURE_EXPIRED
,
3294 DNSSEC_UNSUPPORTED_ALGORITHM
)) {
3296 r
= dns_transaction_dnskey_authenticated(t
, rr
);
3297 if (r
< 0 && r
!= -ENXIO
)
3300 /* The DNSKEY transaction was not authenticated, this means there's
3301 * no DS for this, which means it's OK if no keys are found for this signature. */
3303 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0, NULL
);
3307 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
3312 r
= dns_transaction_is_primary_response(t
, rr
);
3316 /* Look for a matching DNAME for this CNAME */
3317 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
3321 /* Also look among the stuff we already validated */
3322 r
= dns_answer_has_dname_for_cname(*validated
, rr
);
3330 DNSSEC_SIGNATURE_EXPIRED
,
3331 DNSSEC_NO_SIGNATURE
))
3332 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, rr
->key
);
3333 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
3334 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, rr
->key
);
3336 /* This is a primary response to our question, and it failed validation.
3338 t
->answer_dnssec_result
= result
;
3342 /* This is a primary response, but we do have a DNAME RR
3343 * in the RR that can replay this CNAME, hence rely on
3344 * that, and we can remove the CNAME in favour of it. */
3347 /* This is just some auxiliary data. Just remove the RRset and continue. */
3348 r
= dns_answer_remove_by_key(&t
->answer
, rr
->key
);
3352 /* We dropped something from the answer, start from the beginning. */
3356 return 2; /* Finito. */
3359 int dns_transaction_validate_dnssec(DnsTransaction
*t
) {
3360 _cleanup_(dns_answer_unrefp
) DnsAnswer
*validated
= NULL
;
3362 DnsAnswerFlags flags
;
3364 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
3368 /* We have now collected all DS and DNSKEY RRs in t->validated_keys, let's see which RRs we can now
3369 * authenticate with that. */
3371 if (FLAGS_SET(t
->query_flags
, SD_RESOLVED_NO_VALIDATE
) || t
->scope
->dnssec_mode
== DNSSEC_NO
)
3374 /* Already validated */
3375 if (t
->answer_dnssec_result
!= _DNSSEC_RESULT_INVALID
)
3378 /* Our own stuff needs no validation */
3379 if (IN_SET(t
->answer_source
, DNS_TRANSACTION_ZONE
, DNS_TRANSACTION_TRUST_ANCHOR
)) {
3380 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3381 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
, true);
3385 /* Cached stuff is not affected by validation. */
3386 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
3389 if (!dns_transaction_dnssec_supported_full(t
)) {
3390 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
3391 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
3392 log_debug("Not validating response for %" PRIu16
", used server feature level does not support DNSSEC.", t
->id
);
3396 log_debug("Validating response from transaction %" PRIu16
" (%s).",
3398 dns_resource_key_to_string(dns_transaction_key(t
), key_str
, sizeof key_str
));
3400 /* First, see if this response contains any revoked trust
3401 * anchors we care about */
3402 r
= dns_transaction_check_revoked_trust_anchors(t
);
3406 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
3407 r
= dns_transaction_copy_validated(t
);
3411 /* Second, see if there are DNSKEYs we already know a
3412 * validated DS for. */
3413 r
= dns_transaction_validate_dnskey_by_ds(t
);
3417 /* Fourth, remove all DNSKEY and DS RRs again that our trust
3418 * anchor says are revoked. After all we might have marked
3419 * some keys revoked above, but they might still be lingering
3420 * in our validated_keys list. */
3421 r
= dns_transaction_invalidate_revoked_keys(t
);
3425 phase
= DNSSEC_PHASE_DNSKEY
;
3427 bool have_nsec
= false;
3429 r
= dnssec_validate_records(t
, phase
, &have_nsec
, &validated
);
3433 /* Try again as long as we managed to achieve something */
3437 if (phase
== DNSSEC_PHASE_DNSKEY
&& have_nsec
) {
3438 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
3439 phase
= DNSSEC_PHASE_NSEC
;
3443 if (phase
!= DNSSEC_PHASE_ALL
) {
3444 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
3445 * Note that in this third phase we start to remove RRs we couldn't validate. */
3446 phase
= DNSSEC_PHASE_ALL
;
3454 dns_answer_unref(t
->answer
);
3455 t
->answer
= TAKE_PTR(validated
);
3457 /* At this point the answer only contains validated
3458 * RRsets. Now, let's see if it actually answers the question
3459 * we asked. If so, great! If it doesn't, then see if
3460 * NSEC/NSEC3 can prove this. */
3461 r
= dns_transaction_has_positive_answer(t
, &flags
);
3463 /* Yes, it answers the question! */
3465 if (flags
& DNS_ANSWER_AUTHENTICATED
) {
3466 /* The answer is fully authenticated, yay. */
3467 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3468 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3469 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
, true);
3471 /* The answer is not fully authenticated. */
3472 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3473 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
, false);
3476 } else if (r
== 0) {
3477 DnssecNsecResult nr
;
3478 bool authenticated
= false;
3480 /* Bummer! Let's check NSEC/NSEC3 */
3481 r
= dnssec_nsec_test(t
->answer
, dns_transaction_key(t
), &nr
, &authenticated
, &t
->answer_nsec_ttl
);
3487 case DNSSEC_NSEC_NXDOMAIN
:
3488 /* NSEC proves the domain doesn't exist. Very good. */
3489 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3490 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3491 t
->answer_rcode
= DNS_RCODE_NXDOMAIN
;
3492 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
, authenticated
);
3494 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, dns_transaction_key(t
));
3497 case DNSSEC_NSEC_NODATA
:
3498 /* NSEC proves that there's no data here, very good. */
3499 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3500 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3501 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3502 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
, authenticated
);
3504 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, dns_transaction_key(t
));
3507 case DNSSEC_NSEC_OPTOUT
:
3508 /* NSEC3 says the data might not be signed */
3509 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3510 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3511 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
, false);
3513 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, dns_transaction_key(t
));
3516 case DNSSEC_NSEC_NO_RR
:
3517 /* No NSEC data? Bummer! */
3519 r
= dns_transaction_requires_nsec(t
);
3523 t
->answer_dnssec_result
= DNSSEC_NO_SIGNATURE
;
3524 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, dns_transaction_key(t
));
3526 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3527 SET_FLAG(t
->answer_query_flags
, SD_RESOLVED_AUTHENTICATED
, false);
3528 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, dns_transaction_key(t
));
3533 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM
:
3534 /* We don't know the NSEC3 algorithm used? */
3535 t
->answer_dnssec_result
= DNSSEC_UNSUPPORTED_ALGORITHM
;
3536 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, dns_transaction_key(t
));
3539 case DNSSEC_NSEC_FOUND
:
3540 case DNSSEC_NSEC_CNAME
:
3541 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3542 t
->answer_dnssec_result
= DNSSEC_NSEC_MISMATCH
;
3543 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, dns_transaction_key(t
));
3547 assert_not_reached();
3554 static const char* const dns_transaction_state_table
[_DNS_TRANSACTION_STATE_MAX
] = {
3555 [DNS_TRANSACTION_NULL
] = "null",
3556 [DNS_TRANSACTION_PENDING
] = "pending",
3557 [DNS_TRANSACTION_VALIDATING
] = "validating",
3558 [DNS_TRANSACTION_RCODE_FAILURE
] = "rcode-failure",
3559 [DNS_TRANSACTION_SUCCESS
] = "success",
3560 [DNS_TRANSACTION_NO_SERVERS
] = "no-servers",
3561 [DNS_TRANSACTION_TIMEOUT
] = "timeout",
3562 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
] = "attempts-max-reached",
3563 [DNS_TRANSACTION_INVALID_REPLY
] = "invalid-reply",
3564 [DNS_TRANSACTION_ERRNO
] = "errno",
3565 [DNS_TRANSACTION_ABORTED
] = "aborted",
3566 [DNS_TRANSACTION_DNSSEC_FAILED
] = "dnssec-failed",
3567 [DNS_TRANSACTION_NO_TRUST_ANCHOR
] = "no-trust-anchor",
3568 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
] = "rr-type-unsupported",
3569 [DNS_TRANSACTION_NETWORK_DOWN
] = "network-down",
3570 [DNS_TRANSACTION_NOT_FOUND
] = "not-found",
3571 [DNS_TRANSACTION_NO_SOURCE
] = "no-source",
3572 [DNS_TRANSACTION_STUB_LOOP
] = "stub-loop",
3574 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state
, DnsTransactionState
);
3576 static const char* const dns_transaction_source_table
[_DNS_TRANSACTION_SOURCE_MAX
] = {
3577 [DNS_TRANSACTION_NETWORK
] = "network",
3578 [DNS_TRANSACTION_CACHE
] = "cache",
3579 [DNS_TRANSACTION_ZONE
] = "zone",
3580 [DNS_TRANSACTION_TRUST_ANCHOR
] = "trust-anchor",
3582 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source
, DnsTransactionSource
);