| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include "sd-messages.h" |
| |
| #include "af-list.h" |
| #include "alloc-util.h" |
| #include "dns-domain.h" |
| #include "errno-list.h" |
| #include "errno-util.h" |
| #include "fd-util.h" |
| #include "glyph-util.h" |
| #include "random-util.h" |
| #include "resolved-dns-cache.h" |
| #include "resolved-dns-transaction.h" |
| #include "resolved-dnstls.h" |
| #include "resolved-llmnr.h" |
| #include "string-table.h" |
| |
| #define TRANSACTIONS_MAX 4096 |
| #define TRANSACTION_TCP_TIMEOUT_USEC (10U*USEC_PER_SEC) |
| |
| /* After how much time to repeat classic DNS requests */ |
| #define DNS_TIMEOUT_USEC (SD_RESOLVED_QUERY_TIMEOUT_USEC / DNS_TRANSACTION_ATTEMPTS_MAX) |
| |
| static void dns_transaction_reset_answer(DnsTransaction *t) { |
| assert(t); |
| |
| t->received = dns_packet_unref(t->received); |
| t->answer = dns_answer_unref(t->answer); |
| t->answer_rcode = 0; |
| t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; |
| t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID; |
| t->answer_query_flags = 0; |
| t->answer_nsec_ttl = UINT32_MAX; |
| t->answer_errno = 0; |
| } |
| |
| static void dns_transaction_flush_dnssec_transactions(DnsTransaction *t) { |
| DnsTransaction *z; |
| |
| assert(t); |
| |
| while ((z = set_steal_first(t->dnssec_transactions))) { |
| set_remove(z->notify_transactions, t); |
| set_remove(z->notify_transactions_done, t); |
| dns_transaction_gc(z); |
| } |
| } |
| |
| static void dns_transaction_close_connection( |
| DnsTransaction *t, |
| bool use_graveyard) { /* Set use_graveyard = false when you know the connection is already |
| * dead, for example because you got a connection error back from the |
| * kernel. In that case there's no point in keeping the fd around, |
| * hence don't. */ |
| int r; |
| |
| assert(t); |
| |
| if (t->stream) { |
| /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */ |
| LIST_REMOVE(transactions_by_stream, t->stream->transactions, t); |
| |
| /* Remove packet in case it's still in the queue */ |
| dns_packet_unref(ordered_set_remove(t->stream->write_queue, t->sent)); |
| |
| t->stream = dns_stream_unref(t->stream); |
| } |
| |
| t->dns_udp_event_source = sd_event_source_disable_unref(t->dns_udp_event_source); |
| |
| /* If we have an UDP socket where we sent a packet, but never received one, then add it to the socket |
| * graveyard, instead of closing it right away. That way it will stick around for a moment longer, |
| * and the reply we might still get from the server will be eaten up instead of resulting in an ICMP |
| * port unreachable error message. */ |
| |
| if (use_graveyard && t->dns_udp_fd >= 0 && t->sent && !t->received) { |
| r = manager_add_socket_to_graveyard(t->scope->manager, t->dns_udp_fd); |
| if (r < 0) |
| log_debug_errno(r, "Failed to add UDP socket to graveyard, closing immediately: %m"); |
| else |
| TAKE_FD(t->dns_udp_fd); |
| } |
| |
| t->dns_udp_fd = safe_close(t->dns_udp_fd); |
| } |
| |
| static void dns_transaction_stop_timeout(DnsTransaction *t) { |
| assert(t); |
| |
| t->timeout_event_source = sd_event_source_disable_unref(t->timeout_event_source); |
| } |
| |
| DnsTransaction* dns_transaction_free(DnsTransaction *t) { |
| DnsQueryCandidate *c; |
| DnsZoneItem *i; |
| DnsTransaction *z; |
| |
| if (!t) |
| return NULL; |
| |
| log_debug("Freeing transaction %" PRIu16 ".", t->id); |
| |
| dns_transaction_close_connection(t, true); |
| dns_transaction_stop_timeout(t); |
| |
| dns_packet_unref(t->sent); |
| dns_transaction_reset_answer(t); |
| |
| dns_server_unref(t->server); |
| |
| if (t->scope) { |
| if (t->key) { |
| DnsTransaction *first; |
| |
| first = hashmap_get(t->scope->transactions_by_key, t->key); |
| LIST_REMOVE(transactions_by_key, first, t); |
| if (first) |
| hashmap_replace(t->scope->transactions_by_key, first->key, first); |
| else |
| hashmap_remove(t->scope->transactions_by_key, t->key); |
| } |
| |
| LIST_REMOVE(transactions_by_scope, t->scope->transactions, t); |
| |
| if (t->id != 0) |
| hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id)); |
| } |
| |
| while ((c = set_steal_first(t->notify_query_candidates))) |
| set_remove(c->transactions, t); |
| set_free(t->notify_query_candidates); |
| |
| while ((c = set_steal_first(t->notify_query_candidates_done))) |
| set_remove(c->transactions, t); |
| set_free(t->notify_query_candidates_done); |
| |
| while ((i = set_steal_first(t->notify_zone_items))) |
| i->probe_transaction = NULL; |
| set_free(t->notify_zone_items); |
| |
| while ((i = set_steal_first(t->notify_zone_items_done))) |
| i->probe_transaction = NULL; |
| set_free(t->notify_zone_items_done); |
| |
| while ((z = set_steal_first(t->notify_transactions))) |
| set_remove(z->dnssec_transactions, t); |
| set_free(t->notify_transactions); |
| |
| while ((z = set_steal_first(t->notify_transactions_done))) |
| set_remove(z->dnssec_transactions, t); |
| set_free(t->notify_transactions_done); |
| |
| dns_transaction_flush_dnssec_transactions(t); |
| set_free(t->dnssec_transactions); |
| |
| dns_answer_unref(t->validated_keys); |
| dns_resource_key_unref(t->key); |
| dns_packet_unref(t->bypass); |
| |
| return mfree(t); |
| } |
| |
| DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free); |
| |
| DnsTransaction* dns_transaction_gc(DnsTransaction *t) { |
| assert(t); |
| |
| /* Returns !NULL if we can't gc yet. */ |
| |
| if (t->block_gc > 0) |
| return t; |
| |
| if (set_isempty(t->notify_query_candidates) && |
| set_isempty(t->notify_query_candidates_done) && |
| set_isempty(t->notify_zone_items) && |
| set_isempty(t->notify_zone_items_done) && |
| set_isempty(t->notify_transactions) && |
| set_isempty(t->notify_transactions_done)) |
| return dns_transaction_free(t); |
| |
| return t; |
| } |
| |
| static uint16_t pick_new_id(Manager *m) { |
| uint16_t new_id; |
| |
| /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the |
| * number of transactions, and it's much lower than the space of IDs. */ |
| |
| assert_cc(TRANSACTIONS_MAX < 0xFFFF); |
| |
| do |
| random_bytes(&new_id, sizeof(new_id)); |
| while (new_id == 0 || |
| hashmap_get(m->dns_transactions, UINT_TO_PTR(new_id))); |
| |
| return new_id; |
| } |
| |
| static int key_ok( |
| DnsScope *scope, |
| DnsResourceKey *key) { |
| |
| /* Don't allow looking up invalid or pseudo RRs */ |
| if (!dns_type_is_valid_query(key->type)) |
| return -EINVAL; |
| if (dns_type_is_obsolete(key->type)) |
| return -EOPNOTSUPP; |
| |
| /* We only support the IN class */ |
| if (!IN_SET(key->class, DNS_CLASS_IN, DNS_CLASS_ANY)) |
| return -EOPNOTSUPP; |
| |
| /* Don't allows DNSSEC RRs to be looked up via LLMNR/mDNS. They don't really make sense |
| * there, and it speeds up our queries if we refuse this early */ |
| if (scope->protocol != DNS_PROTOCOL_DNS && |
| dns_type_is_dnssec(key->type)) |
| return -EOPNOTSUPP; |
| |
| return 0; |
| } |
| |
| int dns_transaction_new( |
| DnsTransaction **ret, |
| DnsScope *s, |
| DnsResourceKey *key, |
| DnsPacket *bypass, |
| uint64_t query_flags) { |
| |
| _cleanup_(dns_transaction_freep) DnsTransaction *t = NULL; |
| int r; |
| |
| assert(ret); |
| assert(s); |
| |
| if (key) { |
| assert(!bypass); |
| |
| r = key_ok(s, key); |
| if (r < 0) |
| return r; |
| } else { |
| DnsResourceKey *qk; |
| assert(bypass); |
| |
| r = dns_packet_validate_query(bypass); |
| if (r < 0) |
| return r; |
| |
| DNS_QUESTION_FOREACH(qk, bypass->question) { |
| r = key_ok(s, qk); |
| if (r < 0) |
| return r; |
| } |
| } |
| |
| if (hashmap_size(s->manager->dns_transactions) >= TRANSACTIONS_MAX) |
| return -EBUSY; |
| |
| r = hashmap_ensure_allocated(&s->manager->dns_transactions, NULL); |
| if (r < 0) |
| return r; |
| |
| if (key) { |
| r = hashmap_ensure_allocated(&s->transactions_by_key, &dns_resource_key_hash_ops); |
| if (r < 0) |
| return r; |
| } |
| |
| t = new(DnsTransaction, 1); |
| if (!t) |
| return -ENOMEM; |
| |
| *t = (DnsTransaction) { |
| .dns_udp_fd = -EBADF, |
| .answer_source = _DNS_TRANSACTION_SOURCE_INVALID, |
| .answer_dnssec_result = _DNSSEC_RESULT_INVALID, |
| .answer_nsec_ttl = UINT32_MAX, |
| .key = dns_resource_key_ref(key), |
| .query_flags = query_flags, |
| .bypass = dns_packet_ref(bypass), |
| .current_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID, |
| .clamp_feature_level_servfail = _DNS_SERVER_FEATURE_LEVEL_INVALID, |
| .clamp_feature_level_nxdomain = _DNS_SERVER_FEATURE_LEVEL_INVALID, |
| .id = pick_new_id(s->manager), |
| }; |
| |
| r = hashmap_put(s->manager->dns_transactions, UINT_TO_PTR(t->id), t); |
| if (r < 0) { |
| t->id = 0; |
| return r; |
| } |
| |
| if (t->key) { |
| DnsTransaction *first; |
| |
| first = hashmap_get(s->transactions_by_key, t->key); |
| LIST_PREPEND(transactions_by_key, first, t); |
| |
| r = hashmap_replace(s->transactions_by_key, first->key, first); |
| if (r < 0) { |
| LIST_REMOVE(transactions_by_key, first, t); |
| return r; |
| } |
| } |
| |
| LIST_PREPEND(transactions_by_scope, s->transactions, t); |
| t->scope = s; |
| |
| s->manager->n_transactions_total++; |
| |
| if (ret) |
| *ret = t; |
| |
| TAKE_PTR(t); |
| return 0; |
| } |
| |
| static void dns_transaction_shuffle_id(DnsTransaction *t) { |
| uint16_t new_id; |
| assert(t); |
| |
| /* Pick a new ID for this transaction. */ |
| |
| new_id = pick_new_id(t->scope->manager); |
| assert_se(hashmap_remove_and_put(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id), UINT_TO_PTR(new_id), t) >= 0); |
| |
| log_debug("Transaction %" PRIu16 " is now %" PRIu16 ".", t->id, new_id); |
| t->id = new_id; |
| |
| /* Make sure we generate a new packet with the new ID */ |
| t->sent = dns_packet_unref(t->sent); |
| } |
| |
| static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) { |
| char key_str[DNS_RESOURCE_KEY_STRING_MAX]; |
| DnsZoneItem *z; |
| |
| assert(t); |
| assert(p); |
| assert(t->scope->protocol == DNS_PROTOCOL_LLMNR); |
| |
| if (manager_packet_from_local_address(t->scope->manager, p) != 0) |
| return; |
| |
| log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s got tentative packet from %s.", |
| t->id, |
| dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str), |
| dns_protocol_to_string(t->scope->protocol), |
| t->scope->link ? t->scope->link->ifname : "*", |
| af_to_name_short(t->scope->family), |
| IN_ADDR_TO_STRING(p->family, &p->sender)); |
| |
| /* RFC 4795, Section 4.1 says that the peer with the |
| * lexicographically smaller IP address loses */ |
| if (memcmp(&p->sender, &p->destination, FAMILY_ADDRESS_SIZE(p->family)) >= 0) { |
| log_debug("Peer has lexicographically larger IP address and thus lost in the conflict."); |
| return; |
| } |
| |
| log_debug("We have the lexicographically larger IP address and thus lost in the conflict."); |
| |
| t->block_gc++; |
| |
| while ((z = set_first(t->notify_zone_items))) { |
| /* First, make sure the zone item drops the reference |
| * to us */ |
| dns_zone_item_probe_stop(z); |
| |
| /* Secondly, report this as conflict, so that we might |
| * look for a different hostname */ |
| dns_zone_item_conflict(z); |
| } |
| t->block_gc--; |
| |
| dns_transaction_gc(t); |
| } |
| |
| void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state) { |
| DnsQueryCandidate *c; |
| DnsZoneItem *z; |
| DnsTransaction *d; |
| const char *st; |
| char key_str[DNS_RESOURCE_KEY_STRING_MAX]; |
| |
| assert(t); |
| assert(!DNS_TRANSACTION_IS_LIVE(state)); |
| |
| if (state == DNS_TRANSACTION_DNSSEC_FAILED) { |
| dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str); |
| |
| log_struct(LOG_NOTICE, |
| "MESSAGE_ID=" SD_MESSAGE_DNSSEC_FAILURE_STR, |
| LOG_MESSAGE("DNSSEC validation failed for question %s: %s", |
| key_str, dnssec_result_to_string(t->answer_dnssec_result)), |
| "DNS_TRANSACTION=%" PRIu16, t->id, |
| "DNS_QUESTION=%s", key_str, |
| "DNSSEC_RESULT=%s", dnssec_result_to_string(t->answer_dnssec_result), |
| "DNS_SERVER=%s", strna(dns_server_string_full(t->server)), |
| "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t->server->possible_feature_level)); |
| } |
| |
| /* Note that this call might invalidate the query. Callers |
| * should hence not attempt to access the query or transaction |
| * after calling this function. */ |
| |
| if (state == DNS_TRANSACTION_ERRNO) |
| st = errno_to_name(t->answer_errno); |
| else |
| st = dns_transaction_state_to_string(state); |
| |
| log_debug("%s transaction %" PRIu16 " for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s; %s).", |
| t->bypass ? "Bypass" : "Regular", |
| t->id, |
| dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str), |
| dns_protocol_to_string(t->scope->protocol), |
| t->scope->link ? t->scope->link->ifname : "*", |
| af_to_name_short(t->scope->family), |
| st, |
| t->answer_source < 0 ? "none" : dns_transaction_source_to_string(t->answer_source), |
| FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) ? "not validated" : |
| (FLAGS_SET(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED) ? "authenticated" : "unsigned"), |
| FLAGS_SET(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL) ? "confidential" : "non-confidential"); |
| |
| t->state = state; |
| |
| dns_transaction_close_connection(t, true); |
| dns_transaction_stop_timeout(t); |
| |
| /* Notify all queries that are interested, but make sure the |
| * transaction isn't freed while we are still looking at it */ |
| t->block_gc++; |
| |
| SET_FOREACH_MOVE(c, t->notify_query_candidates_done, t->notify_query_candidates) |
| dns_query_candidate_notify(c); |
| SWAP_TWO(t->notify_query_candidates, t->notify_query_candidates_done); |
| |
| SET_FOREACH_MOVE(z, t->notify_zone_items_done, t->notify_zone_items) |
| dns_zone_item_notify(z); |
| SWAP_TWO(t->notify_zone_items, t->notify_zone_items_done); |
| if (t->probing && t->state == DNS_TRANSACTION_ATTEMPTS_MAX_REACHED) |
| (void) dns_scope_announce(t->scope, false); |
| |
| SET_FOREACH_MOVE(d, t->notify_transactions_done, t->notify_transactions) |
| dns_transaction_notify(d, t); |
| SWAP_TWO(t->notify_transactions, t->notify_transactions_done); |
| |
| t->block_gc--; |
| dns_transaction_gc(t); |
| } |
| |
| static void dns_transaction_complete_errno(DnsTransaction *t, int error) { |
| assert(t); |
| assert(error != 0); |
| |
| t->answer_errno = abs(error); |
| dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); |
| } |
| |
| static int dns_transaction_pick_server(DnsTransaction *t) { |
| DnsServer *server; |
| |
| assert(t); |
| assert(t->scope->protocol == DNS_PROTOCOL_DNS); |
| |
| /* Pick a DNS server and a feature level for it. */ |
| |
| server = dns_scope_get_dns_server(t->scope); |
| if (!server) |
| return -ESRCH; |
| |
| /* If we changed the server invalidate the feature level clamping, as the new server might have completely |
| * different properties. */ |
| if (server != t->server) { |
| t->clamp_feature_level_servfail = _DNS_SERVER_FEATURE_LEVEL_INVALID; |
| t->clamp_feature_level_nxdomain = _DNS_SERVER_FEATURE_LEVEL_INVALID; |
| } |
| |
| t->current_feature_level = dns_server_possible_feature_level(server); |
| |
| /* Clamp the feature level if that is requested. */ |
| if (t->clamp_feature_level_servfail != _DNS_SERVER_FEATURE_LEVEL_INVALID && |
| t->current_feature_level > t->clamp_feature_level_servfail) |
| t->current_feature_level = t->clamp_feature_level_servfail; |
| if (t->clamp_feature_level_nxdomain != _DNS_SERVER_FEATURE_LEVEL_INVALID && |
| t->current_feature_level > t->clamp_feature_level_nxdomain) |
| t->current_feature_level = t->clamp_feature_level_nxdomain; |
| |
| log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t->current_feature_level), t->id); |
| |
| if (server == t->server) |
| return 0; |
| |
| dns_server_unref(t->server); |
| t->server = dns_server_ref(server); |
| |
| t->n_picked_servers ++; |
| |
| log_debug("Using DNS server %s for transaction %u.", strna(dns_server_string_full(t->server)), t->id); |
| |
| return 1; |
| } |
| |
| static void dns_transaction_retry(DnsTransaction *t, bool next_server) { |
| int r; |
| |
| assert(t); |
| |
| /* Retries the transaction as it is, possibly on a different server */ |
| |
| if (next_server && t->scope->protocol == DNS_PROTOCOL_DNS) |
| log_debug("Retrying transaction %" PRIu16 ", after switching servers.", t->id); |
| else |
| log_debug("Retrying transaction %" PRIu16 ".", t->id); |
| |
| /* Before we try again, switch to a new server. */ |
| if (next_server) |
| dns_scope_next_dns_server(t->scope, t->server); |
| |
| r = dns_transaction_go(t); |
| if (r < 0) |
| dns_transaction_complete_errno(t, r); |
| } |
| |
| static bool dns_transaction_limited_retry(DnsTransaction *t) { |
| assert(t); |
| |
| /* If we haven't tried all different servers yet, let's try again with a different server */ |
| |
| if (t->n_picked_servers >= dns_scope_get_n_dns_servers(t->scope)) |
| return false; |
| |
| dns_transaction_retry(t, /* next_server= */ true); |
| return true; |
| } |
| |
| static int dns_transaction_maybe_restart(DnsTransaction *t) { |
| int r; |
| |
| assert(t); |
| |
| /* Restarts the transaction, under a new ID if the feature level of the server changed since we first |
| * tried, without changing DNS server. Returns > 0 if the transaction was restarted, 0 if not. */ |
| |
| if (!t->server) |
| return 0; |
| |
| if (t->current_feature_level <= dns_server_possible_feature_level(t->server)) |
| return 0; |
| |
| /* The server's current feature level is lower than when we sent the original query. We learnt something from |
| the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to |
| restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include |
| OPT RR or DO bit. One of these cases is documented here, for example: |
| https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */ |
| |
| log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID."); |
| dns_transaction_shuffle_id(t); |
| |
| r = dns_transaction_go(t); |
| if (r < 0) |
| return r; |
| |
| return 1; |
| } |
| |
| static void on_transaction_stream_error(DnsTransaction *t, int error) { |
| assert(t); |
| |
| dns_transaction_close_connection(t, true); |
| |
| if (ERRNO_IS_DISCONNECT(error)) { |
| if (t->scope->protocol == DNS_PROTOCOL_LLMNR) { |
| /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the |
| * question on this scope. */ |
| dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND); |
| return; |
| } |
| |
| dns_transaction_retry(t, true); |
| return; |
| } |
| if (error != 0) |
| dns_transaction_complete_errno(t, error); |
| } |
| |
| static int dns_transaction_on_stream_packet(DnsTransaction *t, DnsStream *s, DnsPacket *p) { |
| bool encrypted; |
| |
| assert(t); |
| assert(s); |
| assert(p); |
| |
| encrypted = s->encrypted; |
| |
| dns_transaction_close_connection(t, true); |
| |
| if (dns_packet_validate_reply(p) <= 0) { |
| log_debug("Invalid TCP reply packet."); |
| dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); |
| return 0; |
| } |
| |
| dns_scope_check_conflicts(t->scope, p); |
| |
| t->block_gc++; |
| dns_transaction_process_reply(t, p, encrypted); |
| t->block_gc--; |
| |
| /* If the response wasn't useful, then complete the transition |
| * now. After all, we are the worst feature set now with TCP |
| * sockets, and there's really no point in retrying. */ |
| if (t->state == DNS_TRANSACTION_PENDING) |
| dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); |
| else |
| dns_transaction_gc(t); |
| |
| return 0; |
| } |
| |
| static int on_stream_complete(DnsStream *s, int error) { |
| assert(s); |
| |
| if (ERRNO_IS_DISCONNECT(error) && s->protocol != DNS_PROTOCOL_LLMNR) { |
| log_debug_errno(error, "Connection failure for DNS TCP stream: %m"); |
| |
| if (s->transactions) { |
| DnsTransaction *t; |
| |
| t = s->transactions; |
| dns_server_packet_lost(t->server, IPPROTO_TCP, t->current_feature_level); |
| } |
| } |
| |
| if (error != 0) |
| LIST_FOREACH(transactions_by_stream, t, s->transactions) |
| on_transaction_stream_error(t, error); |
| |
| return 0; |
| } |
| |
| static int on_stream_packet(DnsStream *s, DnsPacket *p) { |
| DnsTransaction *t; |
| |
| assert(s); |
| assert(s->manager); |
| assert(p); |
| |
| t = hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p))); |
| if (t && t->stream == s) /* Validate that the stream we got this on actually is the stream the |
| * transaction was using. */ |
| return dns_transaction_on_stream_packet(t, s, p); |
| |
| /* Ignore incorrect transaction id as an old transaction can have been canceled. */ |
| log_debug("Received unexpected TCP reply packet with id %" PRIu16 ", ignoring.", DNS_PACKET_ID(p)); |
| return 0; |
| } |
| |
| static uint16_t dns_transaction_port(DnsTransaction *t) { |
| assert(t); |
| |
| if (t->server->port > 0) |
| return t->server->port; |
| |
| return DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) ? 853 : 53; |
| } |
| |
| static int dns_transaction_emit_tcp(DnsTransaction *t) { |
| usec_t stream_timeout_usec = DNS_STREAM_DEFAULT_TIMEOUT_USEC; |
| _cleanup_(dns_stream_unrefp) DnsStream *s = NULL; |
| _cleanup_close_ int fd = -EBADF; |
| union sockaddr_union sa; |
| DnsStreamType type; |
| int r; |
| |
| assert(t); |
| assert(t->sent); |
| |
| dns_transaction_close_connection(t, true); |
| |
| switch (t->scope->protocol) { |
| |
| case DNS_PROTOCOL_DNS: |
| r = dns_transaction_pick_server(t); |
| if (r < 0) |
| return r; |
| |
| if (manager_server_is_stub(t->scope->manager, t->server)) |
| return -ELOOP; |
| |
| if (!t->bypass) { |
| if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(dns_transaction_key(t)->type)) |
| return -EOPNOTSUPP; |
| |
| r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level); |
| if (r < 0) |
| return r; |
| } |
| |
| if (t->server->stream && (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) == t->server->stream->encrypted)) |
| s = dns_stream_ref(t->server->stream); |
| else |
| fd = dns_scope_socket_tcp(t->scope, AF_UNSPEC, NULL, t->server, dns_transaction_port(t), &sa); |
| |
| /* Lower timeout in DNS-over-TLS opportunistic mode. In environments where DoT is blocked |
| * without ICMP response overly long delays when contacting DoT servers are nasty, in |
| * particular if multiple DNS servers are defined which we try in turn and all are |
| * blocked. Hence, substantially lower the timeout in that case. */ |
| if (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) && |
| dns_server_get_dns_over_tls_mode(t->server) == DNS_OVER_TLS_OPPORTUNISTIC) |
| stream_timeout_usec = DNS_STREAM_OPPORTUNISTIC_TLS_TIMEOUT_USEC; |
| |
| type = DNS_STREAM_LOOKUP; |
| break; |
| |
| case DNS_PROTOCOL_LLMNR: |
| /* When we already received a reply to this (but it was truncated), send to its sender address */ |
| if (t->received) |
| fd = dns_scope_socket_tcp(t->scope, t->received->family, &t->received->sender, NULL, t->received->sender_port, &sa); |
| else { |
| union in_addr_union address; |
| int family = AF_UNSPEC; |
| |
| /* Otherwise, try to talk to the owner of a |
| * the IP address, in case this is a reverse |
| * PTR lookup */ |
| |
| r = dns_name_address(dns_resource_key_name(dns_transaction_key(t)), &family, &address); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| return -EINVAL; |
| if (family != t->scope->family) |
| return -ESRCH; |
| |
| fd = dns_scope_socket_tcp(t->scope, family, &address, NULL, LLMNR_PORT, &sa); |
| } |
| |
| type = DNS_STREAM_LLMNR_SEND; |
| break; |
| |
| default: |
| return -EAFNOSUPPORT; |
| } |
| |
| if (!s) { |
| if (fd < 0) |
| return fd; |
| |
| r = dns_stream_new(t->scope->manager, &s, type, t->scope->protocol, fd, &sa, |
| on_stream_packet, on_stream_complete, stream_timeout_usec); |
| if (r < 0) |
| return r; |
| |
| fd = -EBADF; |
| |
| #if ENABLE_DNS_OVER_TLS |
| if (t->scope->protocol == DNS_PROTOCOL_DNS && |
| DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level)) { |
| |
| assert(t->server); |
| r = dnstls_stream_connect_tls(s, t->server); |
| if (r < 0) |
| return r; |
| } |
| #endif |
| |
| if (t->server) { |
| dns_server_unref_stream(t->server); |
| s->server = dns_server_ref(t->server); |
| t->server->stream = dns_stream_ref(s); |
| } |
| |
| /* The interface index is difficult to determine if we are |
| * connecting to the local host, hence fill this in right away |
| * instead of determining it from the socket */ |
| s->ifindex = dns_scope_ifindex(t->scope); |
| } |
| |
| t->stream = TAKE_PTR(s); |
| LIST_PREPEND(transactions_by_stream, t->stream->transactions, t); |
| |
| r = dns_stream_write_packet(t->stream, t->sent); |
| if (r < 0) { |
| dns_transaction_close_connection(t, /* use_graveyard= */ false); |
| return r; |
| } |
| |
| dns_transaction_reset_answer(t); |
| |
| t->tried_stream = true; |
| |
| return 0; |
| } |
| |
| static void dns_transaction_cache_answer(DnsTransaction *t) { |
| assert(t); |
| |
| /* For mDNS we cache whenever we get the packet, rather than |
| * in each transaction. */ |
| if (!IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR)) |
| return; |
| |
| /* Caching disabled? */ |
| if (t->scope->manager->enable_cache == DNS_CACHE_MODE_NO) |
| return; |
| |
| /* If validation is turned off for this transaction, but DNSSEC is on, then let's not cache this */ |
| if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) && t->scope->dnssec_mode != DNSSEC_NO) |
| return; |
| |
| /* Packet from localhost? */ |
| if (!t->scope->manager->cache_from_localhost && |
| in_addr_is_localhost(t->received->family, &t->received->sender) != 0) |
| return; |
| |
| dns_cache_put(&t->scope->cache, |
| t->scope->manager->enable_cache, |
| t->scope->protocol, |
| dns_transaction_key(t), |
| t->answer_rcode, |
| t->answer, |
| DNS_PACKET_CD(t->received) ? t->received : NULL, /* only cache full packets with CD on, |
| * since our usecase for caching them |
| * is "bypass" mode which is only |
| * enabled for CD packets. */ |
| t->answer_query_flags, |
| t->answer_dnssec_result, |
| t->answer_nsec_ttl, |
| t->received->family, |
| &t->received->sender); |
| } |
| |
| static bool dns_transaction_dnssec_is_live(DnsTransaction *t) { |
| DnsTransaction *dt; |
| |
| assert(t); |
| |
| SET_FOREACH(dt, t->dnssec_transactions) |
| if (DNS_TRANSACTION_IS_LIVE(dt->state)) |
| return true; |
| |
| return false; |
| } |
| |
| static int dns_transaction_dnssec_ready(DnsTransaction *t) { |
| DnsTransaction *dt; |
| int r; |
| |
| assert(t); |
| |
| /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still |
| * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */ |
| |
| SET_FOREACH(dt, t->dnssec_transactions) { |
| |
| switch (dt->state) { |
| |
| case DNS_TRANSACTION_NULL: |
| case DNS_TRANSACTION_PENDING: |
| case DNS_TRANSACTION_VALIDATING: |
| /* Still ongoing */ |
| return 0; |
| |
| case DNS_TRANSACTION_RCODE_FAILURE: |
| if (!IN_SET(dt->answer_rcode, DNS_RCODE_NXDOMAIN, DNS_RCODE_SERVFAIL)) { |
| log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", FORMAT_DNS_RCODE(dt->answer_rcode)); |
| goto fail; |
| } |
| |
| /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers |
| * erroneously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS |
| * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar |
| * RRs to make unsigned proofs. */ |
| |
| case DNS_TRANSACTION_SUCCESS: |
| /* All good. */ |
| break; |
| |
| case DNS_TRANSACTION_DNSSEC_FAILED: |
| /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC |
| * validation result */ |
| |
| log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt->answer_dnssec_result)); |
| t->answer_dnssec_result = dt->answer_dnssec_result; /* Copy error code over */ |
| dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); |
| return 0; |
| |
| default: |
| log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt->state)); |
| goto fail; |
| } |
| } |
| |
| /* All is ready, we can go and validate */ |
| return 1; |
| |
| fail: |
| /* Some auxiliary DNSSEC transaction failed for some reason. Maybe we learned something about the |
| * server due to this failure, and the feature level is now different? Let's see and restart the |
| * transaction if so. If not, let's propagate the auxiliary failure. |
| * |
| * This is particularly relevant if an auxiliary request figured out that DNSSEC doesn't work, and we |
| * are in permissive DNSSEC mode, and thus should restart things without DNSSEC magic. */ |
| r = dns_transaction_maybe_restart(t); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| return 0; /* don't validate just yet, we restarted things */ |
| |
| t->answer_dnssec_result = DNSSEC_FAILED_AUXILIARY; |
| dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); |
| return 0; |
| } |
| |
| static void dns_transaction_process_dnssec(DnsTransaction *t) { |
| int r; |
| |
| assert(t); |
| |
| /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */ |
| r = dns_transaction_dnssec_ready(t); |
| if (r < 0) |
| goto fail; |
| if (r == 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */ |
| return; |
| |
| /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better |
| * restart the lookup immediately. */ |
| r = dns_transaction_maybe_restart(t); |
| if (r < 0) |
| goto fail; |
| if (r > 0) /* Transaction got restarted... */ |
| return; |
| |
| /* All our auxiliary DNSSEC transactions are complete now. Try |
| * to validate our RRset now. */ |
| r = dns_transaction_validate_dnssec(t); |
| if (r == -EBADMSG) { |
| dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); |
| return; |
| } |
| if (r < 0) |
| goto fail; |
| |
| if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER && |
| t->scope->dnssec_mode == DNSSEC_YES) { |
| |
| /* We are not in automatic downgrade mode, and the server is bad. Let's try a different server, maybe |
| * that works. */ |
| |
| if (dns_transaction_limited_retry(t)) |
| return; |
| |
| /* OK, let's give up, apparently all servers we tried didn't work. */ |
| dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); |
| return; |
| } |
| |
| if (!IN_SET(t->answer_dnssec_result, |
| _DNSSEC_RESULT_INVALID, /* No DNSSEC validation enabled */ |
| DNSSEC_VALIDATED, /* Answer is signed and validated successfully */ |
| DNSSEC_UNSIGNED, /* Answer is right-fully unsigned */ |
| DNSSEC_INCOMPATIBLE_SERVER)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */ |
| dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED); |
| return; |
| } |
| |
| if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER) |
| dns_server_warn_downgrade(t->server); |
| |
| dns_transaction_cache_answer(t); |
| |
| if (t->answer_rcode == DNS_RCODE_SUCCESS) |
| dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); |
| else |
| dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE); |
| |
| return; |
| |
| fail: |
| dns_transaction_complete_errno(t, r); |
| } |
| |
| static int dns_transaction_has_positive_answer(DnsTransaction *t, DnsAnswerFlags *flags) { |
| int r; |
| |
| assert(t); |
| |
| /* Checks whether the answer is positive, i.e. either a direct |
| * answer to the question, or a CNAME/DNAME for it */ |
| |
| r = dns_answer_match_key(t->answer, dns_transaction_key(t), flags); |
| if (r != 0) |
| return r; |
| |
| r = dns_answer_find_cname_or_dname(t->answer, dns_transaction_key(t), NULL, flags); |
| if (r != 0) |
| return r; |
| |
| return false; |
| } |
| |
| static int dns_transaction_fix_rcode(DnsTransaction *t) { |
| int r; |
| |
| assert(t); |
| |
| /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the |
| * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a |
| * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first |
| * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when |
| * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle |
| * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a |
| * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server |
| * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an |
| * incomplete CNAME/DNAME chain. |
| * |
| * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS, |
| * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new |
| * lookup. */ |
| |
| if (t->answer_rcode != DNS_RCODE_NXDOMAIN) |
| return 0; |
| |
| r = dns_transaction_has_positive_answer(t, NULL); |
| if (r <= 0) |
| return r; |
| |
| t->answer_rcode = DNS_RCODE_SUCCESS; |
| return 0; |
| } |
| |
| void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p, bool encrypted) { |
| bool retry_with_tcp = false; |
| int r; |
| |
| assert(t); |
| assert(p); |
| assert(t->scope); |
| assert(t->scope->manager); |
| |
| if (t->state != DNS_TRANSACTION_PENDING) |
| return; |
| |
| /* Note that this call might invalidate the query. Callers |
| * should hence not attempt to access the query or transaction |
| * after calling this function. */ |
| |
| log_debug("Processing incoming packet of size %zu on transaction %" PRIu16" (rcode=%s).", |
| p->size, |
| t->id, FORMAT_DNS_RCODE(DNS_PACKET_RCODE(p))); |
| |
| switch (t->scope->protocol) { |
| |
| case DNS_PROTOCOL_LLMNR: |
| /* For LLMNR we will not accept any packets from other interfaces */ |
| |
| if (p->ifindex != dns_scope_ifindex(t->scope)) |
| return; |
| |
| if (p->family != t->scope->family) |
| return; |
| |
| /* Tentative packets are not full responses but still |
| * useful for identifying uniqueness conflicts during |
| * probing. */ |
| if (DNS_PACKET_LLMNR_T(p)) { |
| dns_transaction_tentative(t, p); |
| return; |
| } |
| |
| break; |
| |
| case DNS_PROTOCOL_MDNS: |
| /* For mDNS we will not accept any packets from other interfaces */ |
| |
| if (p->ifindex != dns_scope_ifindex(t->scope)) |
| return; |
| |
| if (p->family != t->scope->family) |
| return; |
| |
| break; |
| |
| case DNS_PROTOCOL_DNS: |
| /* Note that we do not need to verify the |
| * addresses/port numbers of incoming traffic, as we |
| * invoked connect() on our UDP socket in which case |
| * the kernel already does the needed verification for |
| * us. */ |
| break; |
| |
| default: |
| assert_not_reached(); |
| } |
| |
| if (t->received != p) |
| DNS_PACKET_REPLACE(t->received, dns_packet_ref(p)); |
| |
| t->answer_source = DNS_TRANSACTION_NETWORK; |
| |
| if (p->ipproto == IPPROTO_TCP) { |
| if (DNS_PACKET_TC(p)) { |
| /* Truncated via TCP? Somebody must be fucking with us */ |
| dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); |
| return; |
| } |
| |
| if (DNS_PACKET_ID(p) != t->id) { |
| /* Not the reply to our query? Somebody must be fucking with us */ |
| dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); |
| return; |
| } |
| } |
| |
| switch (t->scope->protocol) { |
| |
| case DNS_PROTOCOL_DNS: |
| assert(t->server); |
| |
| if (!t->bypass && |
| IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_FORMERR, DNS_RCODE_SERVFAIL, DNS_RCODE_NOTIMP)) { |
| |
| /* Request failed, immediately try again with reduced features */ |
| |
| if (t->current_feature_level <= DNS_SERVER_FEATURE_LEVEL_UDP) { |
| |
| /* This was already at UDP feature level? If so, it doesn't make sense to downgrade |
| * this transaction anymore, but let's see if it might make sense to send the request |
| * to a different DNS server instead. If not let's process the response, and accept the |
| * rcode. Note that we don't retry on TCP, since that's a suitable way to mitigate |
| * packet loss, but is not going to give us better rcodes should we actually have |
| * managed to get them already at UDP level. */ |
| |
| if (dns_transaction_limited_retry(t)) |
| return; |
| |
| /* Give up, accept the rcode */ |
| log_debug("Server returned error: %s", FORMAT_DNS_RCODE(DNS_PACKET_RCODE(p))); |
| break; |
| } |
| |
| /* SERVFAIL can happen for many reasons and may be transient. |
| * To avoid unnecessary downgrades retry once with the initial level. |
| * Check for clamp_feature_level_servfail having an invalid value as a sign that this is the |
| * first attempt to downgrade. If so, clamp to the current value so that the transaction |
| * is retried without actually downgrading. If the next try also fails we will downgrade by |
| * hitting the else branch below. */ |
| if (DNS_PACKET_RCODE(p) == DNS_RCODE_SERVFAIL && |
| t->clamp_feature_level_servfail < 0) { |
| t->clamp_feature_level_servfail = t->current_feature_level; |
| log_debug("Server returned error %s, retrying transaction.", |
| FORMAT_DNS_RCODE(DNS_PACKET_RCODE(p))); |
| } else { |
| /* Reduce this feature level by one and try again. */ |
| switch (t->current_feature_level) { |
| case DNS_SERVER_FEATURE_LEVEL_TLS_DO: |
| t->clamp_feature_level_servfail = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN; |
| break; |
| case DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN + 1: |
| /* Skip plain TLS when TLS is not supported */ |
| t->clamp_feature_level_servfail = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN - 1; |
| break; |
| default: |
| t->clamp_feature_level_servfail = t->current_feature_level - 1; |
| } |
| |
| log_debug("Server returned error %s, retrying transaction with reduced feature level %s.", |
| FORMAT_DNS_RCODE(DNS_PACKET_RCODE(p)), |
| dns_server_feature_level_to_string(t->clamp_feature_level_servfail)); |
| } |
| |
| dns_transaction_retry(t, false /* use the same server */); |
| return; |
| } |
| |
| if (DNS_PACKET_RCODE(p) == DNS_RCODE_REFUSED) { |
| /* This server refused our request? If so, try again, use a different server */ |
| log_debug("Server returned REFUSED, switching servers, and retrying."); |
| |
| if (dns_transaction_limited_retry(t)) |
| return; |
| |
| break; |
| } |
| |
| if (DNS_PACKET_TC(p)) |
| dns_server_packet_truncated(t->server, t->current_feature_level); |
| |
| break; |
| |
| case DNS_PROTOCOL_LLMNR: |
| case DNS_PROTOCOL_MDNS: |
| dns_scope_packet_received(t->scope, p->timestamp - t->start_usec); |
| break; |
| |
| default: |
| assert_not_reached(); |
| } |
| |
| if (DNS_PACKET_TC(p)) { |
| |
| /* Truncated packets for mDNS are not allowed. Give up immediately. */ |
| if (t->scope->protocol == DNS_PROTOCOL_MDNS) { |
| dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); |
| return; |
| } |
| |
| /* Response was truncated, let's try again with good old TCP */ |
| log_debug("Reply truncated, retrying via TCP."); |
| retry_with_tcp = true; |
| |
| } else if (t->scope->protocol == DNS_PROTOCOL_DNS && |
| DNS_PACKET_IS_FRAGMENTED(p)) { |
| |
| /* Report the fragment size, so that we downgrade from LARGE to regular EDNS0 if needed */ |
| if (t->server) |
| dns_server_packet_udp_fragmented(t->server, dns_packet_size_unfragmented(p)); |
| |
| if (t->current_feature_level > DNS_SERVER_FEATURE_LEVEL_UDP) { |
| /* Packet was fragmented. Let's retry with TCP to avoid fragmentation attack |
| * issues. (We don't do that on the lowest feature level however, since crappy DNS |
| * servers often do not implement TCP, hence falling back to TCP on fragmentation is |
| * counter-productive there.) */ |
| |
| log_debug("Reply fragmented, retrying via TCP. (Largest fragment size: %zu; Datagram size: %zu)", |
| p->fragsize, p->size); |
| retry_with_tcp = true; |
| } |
| } |
| |
| if (retry_with_tcp) { |
| r = dns_transaction_emit_tcp(t); |
| if (r == -ESRCH) { |
| /* No servers found? Damn! */ |
| dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS); |
| return; |
| } |
| if (r == -EOPNOTSUPP) { |
| /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */ |
| dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED); |
| return; |
| } |
| if (r < 0) { |
| /* On LLMNR, if we cannot connect to the host, |
| * we immediately give up */ |
| if (t->scope->protocol != DNS_PROTOCOL_DNS) |
| goto fail; |
| |
| /* On DNS, couldn't send? Try immediately again, with a new server */ |
| if (dns_transaction_limited_retry(t)) |
| return; |
| |
| /* No new server to try, give up */ |
| dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED); |
| } |
| |
| return; |
| } |
| |
| /* After the superficial checks, actually parse the message. */ |
| r = dns_packet_extract(p); |
| if (r < 0) { |
| if (t->server) { |
| dns_server_packet_invalid(t->server, t->current_feature_level); |
| |
| r = dns_transaction_maybe_restart(t); |
| if (r < 0) |
| goto fail; |
| if (r > 0) /* Transaction got restarted... */ |
| return; |
| } |
| |
| dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); |
| return; |
| } |
| |
| if (t->scope->protocol == DNS_PROTOCOL_DNS && |
| !t->bypass && |
| DNS_PACKET_RCODE(p) == DNS_RCODE_NXDOMAIN && |
| p->opt && !DNS_PACKET_DO(p) && |
| DNS_SERVER_FEATURE_LEVEL_IS_EDNS0(t->current_feature_level) && |
| DNS_SERVER_FEATURE_LEVEL_IS_UDP(t->current_feature_level) && |
| t->scope->dnssec_mode != DNSSEC_YES) { |
| |
| /* Some captive portals are special in that the Aruba/Datavalet hardware will miss |
| * replacing the packets with the local server IP to point to the authenticated side |
| * of the network if EDNS0 is enabled. Instead they return NXDOMAIN, with DO bit set |
| * to zero... nothing to see here, yet respond with the captive portal IP, when using |
| * the more simple UDP level. |
| * |
| * Common portal names that fail like so are: |
| * secure.datavalet.io |
| * securelogin.arubanetworks.com |
| * securelogin.networks.mycompany.com |
| * |
| * Thus retry NXDOMAIN RCODES with a lower feature level. |
| * |
| * Do not lower the server's tracked feature level, as the captive portal should not |
| * be lying for the wider internet (e.g. _other_ queries were observed fine with |
| * EDNS0 on these networks, post auth), i.e. let's just lower the level transaction's |
| * feature level. |
| * |
| * This is reported as https://github.com/dns-violations/dns-violations/blob/master/2018/DVE-2018-0001.md |
| */ |
| |
| t->clamp_feature_level_nxdomain = DNS_SERVER_FEATURE_LEVEL_UDP; |
| |
| log_debug("Server returned error %s in EDNS0 mode, retrying transaction with reduced feature level %s (DVE-2018-0001 mitigation)", |
| FORMAT_DNS_RCODE(DNS_PACKET_RCODE(p)), |
| dns_server_feature_level_to_string(t->clamp_feature_level_nxdomain)); |
| |
| dns_transaction_retry(t, false /* use the same server */); |
| return; |
| } |
| |
| if (t->server) { |
| /* Report that we successfully received a valid packet with a good rcode after we initially got a bad |
| * rcode and subsequently downgraded the protocol */ |
| |
| if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN) && |
| t->clamp_feature_level_servfail != _DNS_SERVER_FEATURE_LEVEL_INVALID) |
| dns_server_packet_rcode_downgrade(t->server, t->clamp_feature_level_servfail); |
| |
| /* Report that the OPT RR was missing */ |
| if (!p->opt) |
| dns_server_packet_bad_opt(t->server, t->current_feature_level); |
| |
| /* Report that the server didn't copy our query DO bit from request to response */ |
| if (DNS_PACKET_DO(t->sent) && !DNS_PACKET_DO(t->received)) |
| dns_server_packet_do_off(t->server, t->current_feature_level); |
| |
| /* Report that we successfully received a packet. We keep track of the largest packet |
| * size/fragment size we got. Which is useful for announcing the EDNS(0) packet size we can |
| * receive to our server. */ |
| dns_server_packet_received(t->server, p->ipproto, t->current_feature_level, dns_packet_size_unfragmented(p)); |
| } |
| |
| /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */ |
| r = dns_transaction_maybe_restart(t); |
| if (r < 0) |
| goto fail; |
| if (r > 0) /* Transaction got restarted... */ |
| return; |
| |
| /* When dealing with protocols other than mDNS only consider responses with equivalent query section |
| * to the request. For mDNS this check doesn't make sense, because the section 6 of RFC6762 states |
| * that "Multicast DNS responses MUST NOT contain any questions in the Question Section". */ |
| if (t->scope->protocol != DNS_PROTOCOL_MDNS) { |
| r = dns_packet_is_reply_for(p, dns_transaction_key(t)); |
| if (r < 0) |
| goto fail; |
| if (r == 0) { |
| dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); |
| return; |
| } |
| } |
| |
| /* Install the answer as answer to the transaction. We ref the answer twice here: the main `answer` |
| * field is later replaced by the DNSSEC validated subset. The 'answer_auxiliary' field carries the |
| * original complete record set, including RRSIG and friends. We use this when passing data to |
| * clients that ask for DNSSEC metadata. */ |
| DNS_ANSWER_REPLACE(t->answer, dns_answer_ref(p->answer)); |
| t->answer_rcode = DNS_PACKET_RCODE(p); |
| t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL, encrypted); |
| |
| r = dns_transaction_fix_rcode(t); |
| if (r < 0) |
| goto fail; |
| |
| /* Block GC while starting requests for additional DNSSEC RRs */ |
| t->block_gc++; |
| r = dns_transaction_request_dnssec_keys(t); |
| t->block_gc--; |
| |
| /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */ |
| if (!dns_transaction_gc(t)) |
| return; |
| |
| /* Requesting additional keys might have resulted in this transaction to fail, since the auxiliary |
| * request failed for some reason. If so, we are not in pending state anymore, and we should exit |
| * quickly. */ |
| if (t->state != DNS_TRANSACTION_PENDING) |
| return; |
| if (r < 0) |
| goto fail; |
| if (r > 0) { |
| /* There are DNSSEC transactions pending now. Update the state accordingly. */ |
| t->state = DNS_TRANSACTION_VALIDATING; |
| dns_transaction_close_connection(t, true); |
| dns_transaction_stop_timeout(t); |
| return; |
| } |
| |
| dns_transaction_process_dnssec(t); |
| return; |
| |
| fail: |
| dns_transaction_complete_errno(t, r); |
| } |
| |
| static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { |
| _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
| DnsTransaction *t = ASSERT_PTR(userdata); |
| int r; |
| |
| assert(t->scope); |
| |
| r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p); |
| if (ERRNO_IS_DISCONNECT(r)) { |
| usec_t usec; |
| |
| /* UDP connection failures get reported via ICMP and then are possibly delivered to us on the |
| * next recvmsg(). Treat this like a lost packet. */ |
| |
| log_debug_errno(r, "Connection failure for DNS UDP packet: %m"); |
| assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &usec) >= 0); |
| dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level); |
| |
| dns_transaction_close_connection(t, /* use_graveyard = */ false); |
| |
| if (dns_transaction_limited_retry(t)) /* Try a different server */ |
| return 0; |
| |
| dns_transaction_complete_errno(t, r); |
| return 0; |
| } |
| if (r < 0) { |
| dns_transaction_complete_errno(t, r); |
| return 0; |
| } |
| if (r == 0) |
| /* Spurious wakeup without any data */ |
| return 0; |
| |
| r = dns_packet_validate_reply(p); |
| if (r < 0) { |
| log_debug_errno(r, "Received invalid DNS packet as response, ignoring: %m"); |
| return 0; |
| } |
| if (r == 0) { |
| log_debug("Received inappropriate DNS packet as response, ignoring."); |
| return 0; |
| } |
| |
| if (DNS_PACKET_ID(p) != t->id) { |
| log_debug("Received packet with incorrect transaction ID, ignoring."); |
| return 0; |
| } |
| |
| dns_transaction_process_reply(t, p, false); |
| return 0; |
| } |
| |
| static int dns_transaction_emit_udp(DnsTransaction *t) { |
| int r; |
| |
| assert(t); |
| |
| if (t->scope->protocol == DNS_PROTOCOL_DNS) { |
| |
| r = dns_transaction_pick_server(t); |
| if (r < 0) |
| return r; |
| |
| if (manager_server_is_stub(t->scope->manager, t->server)) |
| return -ELOOP; |
| |
| if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_UDP || DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level)) |
| return -EAGAIN; /* Sorry, can't do UDP, try TCP! */ |
| |
| if (!t->bypass && !dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(dns_transaction_key(t)->type)) |
| return -EOPNOTSUPP; |
| |
| if (r > 0 || t->dns_udp_fd < 0) { /* Server changed, or no connection yet. */ |
| int fd; |
| |
| dns_transaction_close_connection(t, true); |
| |
| /* Before we allocate a new UDP socket, let's process the graveyard a bit to free some fds */ |
| manager_socket_graveyard_process(t->scope->manager); |
| |
| fd = dns_scope_socket_udp(t->scope, t->server); |
| if (fd < 0) |
| return fd; |
| |
| r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t); |
| if (r < 0) { |
| safe_close(fd); |
| return r; |
| } |
| |
| (void) sd_event_source_set_description(t->dns_udp_event_source, "dns-transaction-udp"); |
| t->dns_udp_fd = fd; |
| } |
| |
| if (!t->bypass) { |
| r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level); |
| if (r < 0) |
| return r; |
| } |
| } else |
| dns_transaction_close_connection(t, true); |
| |
| r = dns_scope_emit_udp(t->scope, t->dns_udp_fd, t->server ? t->server->family : AF_UNSPEC, t->sent); |
| if (r < 0) |
| return r; |
| |
| dns_transaction_reset_answer(t); |
| |
| return 0; |
| } |
| |
| static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) { |
| DnsTransaction *t = ASSERT_PTR(userdata); |
| |
| assert(s); |
| |
| if (t->initial_jitter_scheduled && !t->initial_jitter_elapsed) { |
| log_debug("Initial jitter phase for transaction %" PRIu16 " elapsed.", t->id); |
| t->initial_jitter_elapsed = true; |
| } else { |
| /* Timeout reached? Increase the timeout for the server used */ |
| switch (t->scope->protocol) { |
| |
| case DNS_PROTOCOL_DNS: |
| assert(t->server); |
| dns_server_packet_lost(t->server, t->stream ? IPPROTO_TCP : IPPROTO_UDP, t->current_feature_level); |
| break; |
| |
| case DNS_PROTOCOL_LLMNR: |
| case DNS_PROTOCOL_MDNS: |
| dns_scope_packet_lost(t->scope, usec - t->start_usec); |
| break; |
| |
| default: |
| assert_not_reached(); |
| } |
| |
| log_debug("Timeout reached on transaction %" PRIu16 ".", t->id); |
| } |
| |
| dns_transaction_retry(t, /* next_server= */ true); /* try a different server, but given this means |
| * packet loss, let's do so even if we already |
| * tried a bunch */ |
| return 0; |
| } |
| |
| static int dns_transaction_setup_timeout( |
| DnsTransaction *t, |
| usec_t timeout_usec /* relative */, |
| usec_t next_usec /* CLOCK_BOOTTIME */) { |
| |
| int r; |
| |
| assert(t); |
| |
| dns_transaction_stop_timeout(t); |
| |
| r = sd_event_add_time_relative( |
| t->scope->manager->event, |
| &t->timeout_event_source, |
| CLOCK_BOOTTIME, |
| timeout_usec, 0, |
| on_transaction_timeout, t); |
| if (r < 0) |
| return r; |
| |
| (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout"); |
| |
| t->next_attempt_after = next_usec; |
| t->state = DNS_TRANSACTION_PENDING; |
| return 0; |
| } |
| |
| static usec_t transaction_get_resend_timeout(DnsTransaction *t) { |
| assert(t); |
| assert(t->scope); |
| |
| switch (t->scope->protocol) { |
| |
| case DNS_PROTOCOL_DNS: |
| |
| /* When we do TCP, grant a much longer timeout, as in this case there's no need for us to quickly |
| * resend, as the kernel does that anyway for us, and we really don't want to interrupt it in that |
| * needlessly. */ |
| if (t->stream) |
| return TRANSACTION_TCP_TIMEOUT_USEC; |
| |
| return DNS_TIMEOUT_USEC; |
| |
| case DNS_PROTOCOL_MDNS: |
| if (t->probing) |
| return MDNS_PROBING_INTERVAL_USEC; |
| |
| /* See RFC 6762 Section 5.1 suggests that timeout should be a few seconds. */ |
| assert(t->n_attempts > 0); |
| return (1 << (t->n_attempts - 1)) * USEC_PER_SEC; |
| |
| case DNS_PROTOCOL_LLMNR: |
| return t->scope->resend_timeout; |
| |
| default: |
| assert_not_reached(); |
| } |
| } |
| |
| static void dns_transaction_randomize_answer(DnsTransaction *t) { |
| int r; |
| |
| assert(t); |
| |
| /* Randomizes the order of the answer array. This is done for all cached responses, so that we return |
| * a different order each time. We do this only for DNS traffic, in order to do some minimal, crappy |
| * load balancing. We don't do this for LLMNR or mDNS, since the order (preferring link-local |
| * addresses, and such like) might have meaning there, and load balancing is pointless. */ |
| |
| if (t->scope->protocol != DNS_PROTOCOL_DNS) |
| return; |
| |
| /* No point in randomizing, if there's just one RR */ |
| if (dns_answer_size(t->answer) <= 1) |
| return; |
| |
| r = dns_answer_reserve_or_clone(&t->answer, 0); |
| if (r < 0) /* If this fails, just don't randomize, this is non-essential stuff after all */ |
| return (void) log_debug_errno(r, "Failed to clone answer record, not randomizing RR order of answer: %m"); |
| |
| dns_answer_randomize(t->answer); |
| } |
| |
| static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) { |
| int r; |
| |
| assert(t); |
| |
| /* Returns 0 if dns_transaction_complete() has been called. In that case the transaction and query |
| * candidate objects may have been invalidated and must not be accessed. Returns 1 if the transaction |
| * has been prepared. */ |
| |
| dns_transaction_stop_timeout(t); |
| |
| if (!dns_scope_network_good(t->scope)) { |
| dns_transaction_complete(t, DNS_TRANSACTION_NETWORK_DOWN); |
| return 0; |
| } |
| |
| if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) { |
| DnsTransactionState result; |
| |
| if (t->scope->protocol == DNS_PROTOCOL_LLMNR) |
| /* If we didn't find anything on LLMNR, it's not an error, but a failure to resolve |
| * the name. */ |
| result = DNS_TRANSACTION_NOT_FOUND; |
| else |
| result = DNS_TRANSACTION_ATTEMPTS_MAX_REACHED; |
| |
| dns_transaction_complete(t, result); |
| return 0; |
| } |
| |
| if (t->scope->protocol == DNS_PROTOCOL_LLMNR && t->tried_stream) { |
| /* If we already tried via a stream, then we don't |
| * retry on LLMNR. See RFC 4795, Section 2.7. */ |
| dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED); |
| return 0; |
| } |
| |
| t->n_attempts++; |
| t->start_usec = ts; |
| |
| dns_transaction_reset_answer(t); |
| dns_transaction_flush_dnssec_transactions(t); |
| |
| /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */ |
| if (t->scope->protocol == DNS_PROTOCOL_DNS && |
| !FLAGS_SET(t->query_flags, SD_RESOLVED_NO_TRUST_ANCHOR)) { |
| r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, dns_transaction_key(t), &t->answer); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| t->answer_rcode = DNS_RCODE_SUCCESS; |
| t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED|SD_RESOLVED_CONFIDENTIAL, true); |
| dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); |
| return 0; |
| } |
| |
| if (dns_name_is_root(dns_resource_key_name(dns_transaction_key(t))) && |
| dns_transaction_key(t)->type == DNS_TYPE_DS) { |
| |
| /* Hmm, this is a request for the root DS? A DS RR doesn't exist in the root zone, |
| * and if our trust anchor didn't know it either, this means we cannot do any DNSSEC |
| * logic anymore. */ |
| |
| if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) { |
| /* We are in downgrade mode. In this case, synthesize an unsigned empty |
| * response, so that the any lookup depending on this one can continue |
| * assuming there was no DS, and hence the root zone was unsigned. */ |
| |
| t->answer_rcode = DNS_RCODE_SUCCESS; |
| t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL, true); |
| dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); |
| } else |
| /* If we are not in downgrade mode, then fail the lookup, because we cannot |
| * reasonably answer it. There might be DS RRs, but we don't know them, and |
| * the DNS server won't tell them to us (and even if it would, we couldn't |
| * validate and trust them. */ |
| dns_transaction_complete(t, DNS_TRANSACTION_NO_TRUST_ANCHOR); |
| |
| return 0; |
| } |
| } |
| |
| /* Check the zone. */ |
| if (!FLAGS_SET(t->query_flags, SD_RESOLVED_NO_ZONE)) { |
| r = dns_zone_lookup(&t->scope->zone, dns_transaction_key(t), dns_scope_ifindex(t->scope), &t->answer, NULL, NULL); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| t->answer_rcode = DNS_RCODE_SUCCESS; |
| t->answer_source = DNS_TRANSACTION_ZONE; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED|SD_RESOLVED_CONFIDENTIAL, true); |
| dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); |
| return 0; |
| } |
| } |
| |
| /* Check the cache. */ |
| if (!FLAGS_SET(t->query_flags, SD_RESOLVED_NO_CACHE)) { |
| |
| /* Before trying the cache, let's make sure we figured out a server to use. Should this cause |
| * a change of server this might flush the cache. */ |
| (void) dns_scope_get_dns_server(t->scope); |
| |
| /* Let's then prune all outdated entries */ |
| dns_cache_prune(&t->scope->cache); |
| |
| r = dns_cache_lookup( |
| &t->scope->cache, |
| dns_transaction_key(t), |
| t->query_flags, |
| &t->answer_rcode, |
| &t->answer, |
| &t->received, |
| &t->answer_query_flags, |
| &t->answer_dnssec_result); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| dns_transaction_randomize_answer(t); |
| |
| if (t->bypass && t->scope->protocol == DNS_PROTOCOL_DNS && !t->received) |
| /* When bypass mode is on, do not use cached data unless it came with a full |
| * packet. */ |
| dns_transaction_reset_answer(t); |
| else { |
| t->answer_source = DNS_TRANSACTION_CACHE; |
| if (t->answer_rcode == DNS_RCODE_SUCCESS) |
| dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); |
| else |
| dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE); |
| return 0; |
| } |
| } |
| } |
| |
| if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_NETWORK)) { |
| dns_transaction_complete(t, DNS_TRANSACTION_NO_SOURCE); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static int dns_packet_append_zone(DnsPacket *p, DnsTransaction *t, DnsResourceKey *k, unsigned *nscount) { |
| _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; |
| bool tentative; |
| int r; |
| |
| assert(p); |
| assert(t); |
| assert(k); |
| |
| if (k->type != DNS_TYPE_ANY) |
| return 0; |
| |
| r = dns_zone_lookup(&t->scope->zone, k, t->scope->link->ifindex, &answer, NULL, &tentative); |
| if (r < 0) |
| return r; |
| |
| return dns_packet_append_answer(p, answer, nscount); |
| } |
| |
| static int dns_transaction_make_packet_mdns(DnsTransaction *t) { |
| _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
| _cleanup_set_free_ Set *keys = NULL; |
| unsigned qdcount, ancount = 0 /* avoid false maybe-uninitialized warning */, nscount; |
| bool add_known_answers = false; |
| usec_t ts; |
| int r; |
| |
| assert(t); |
| assert(t->scope->protocol == DNS_PROTOCOL_MDNS); |
| |
| /* Discard any previously prepared packet, so we can start over and coalesce again */ |
| t->sent = dns_packet_unref(t->sent); |
| |
| /* First, create a dummy packet to calculate packet size. */ |
| r = dns_packet_new_query(&p, t->scope->protocol, 0, false); |
| if (r < 0) |
| return r; |
| |
| r = dns_packet_append_key(p, dns_transaction_key(t), 0, NULL); |
| if (r < 0) |
| return r; |
| |
| qdcount = 1; |
| |
| if (dns_key_is_shared(dns_transaction_key(t))) |
| add_known_answers = true; |
| |
| r = dns_packet_append_zone(p, t, dns_transaction_key(t), NULL); |
| if (r < 0) |
| return r; |
| |
| /* Save appended keys */ |
| r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(t)); |
| if (r < 0) |
| return r; |
| |
| /* |
| * For mDNS, we want to coalesce as many open queries in pending transactions into one single |
| * query packet on the wire as possible. To achieve that, we iterate through all pending transactions |
| * in our current scope, and see whether their timing constraints allow them to be sent. |
| */ |
| |
| assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &ts) >= 0); |
| |
| for (bool restart = true; restart;) { |
| restart = false; |
| LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) { |
| size_t saved_packet_size; |
| bool append = false; |
| |
| /* Skip ourselves */ |
| if (other == t) |
| continue; |
| |
| if (other->state != DNS_TRANSACTION_PENDING) |
| continue; |
| |
| if (other->next_attempt_after > ts) |
| continue; |
| |
| if (!set_contains(keys, dns_transaction_key(other))) { |
| r = dns_packet_append_key(p, dns_transaction_key(other), 0, &saved_packet_size); |
| /* If we can't stuff more questions into the packet, just give up. |
| * One of the 'other' transactions will fire later and take care of the rest. */ |
| if (r == -EMSGSIZE) |
| break; |
| if (r < 0) |
| return r; |
| |
| r = dns_packet_append_zone(p, t, dns_transaction_key(other), NULL); |
| if (r == -EMSGSIZE) |
| break; |
| if (r < 0) |
| return r; |
| |
| append = true; |
| } |
| |
| r = dns_transaction_prepare(other, ts); |
| if (r < 0) |
| return r; |
| if (r == 0) { |
| if (append) |
| dns_packet_truncate(p, saved_packet_size); |
| |
| /* In this case, not only this transaction, but multiple transactions may be |
| * freed. Hence, we need to restart the loop. */ |
| restart = true; |
| break; |
| } |
| |
| usec_t timeout = transaction_get_resend_timeout(other); |
| r = dns_transaction_setup_timeout(other, timeout, usec_add(ts, timeout)); |
| if (r < 0) |
| return r; |
| |
| if (dns_key_is_shared(dns_transaction_key(other))) |
| add_known_answers = true; |
| |
| if (append) { |
| r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(other)); |
| if (r < 0) |
| return r; |
| } |
| |
| qdcount++; |
| if (qdcount >= UINT16_MAX) |
| break; |
| } |
| } |
| |
| /* Append known answer section if we're asking for any shared record */ |
| if (add_known_answers) { |
| r = dns_cache_export_shared_to_packet(&t->scope->cache, p, ts, 0); |
| if (r < 0) |
| return r; |
| |
| ancount = be16toh(DNS_PACKET_HEADER(p)->ancount); |
| } |
| |
| /* Then, create actual packet. */ |
| p = dns_packet_unref(p); |
| r = dns_packet_new_query(&p, t->scope->protocol, 0, false); |
| if (r < 0) |
| return r; |
| |
| /* Questions */ |
| DnsResourceKey *k; |
| SET_FOREACH(k, keys) { |
| r = dns_packet_append_key(p, k, 0, NULL); |
| if (r < 0) |
| return r; |
| } |
| DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount); |
| |
| /* Known answers */ |
| if (add_known_answers) { |
| r = dns_cache_export_shared_to_packet(&t->scope->cache, p, ts, ancount); |
| if (r < 0) |
| return r; |
| } |
| |
| /* Authorities */ |
| nscount = 0; |
| SET_FOREACH(k, keys) { |
| r = dns_packet_append_zone(p, t, k, &nscount); |
| if (r < 0) |
| return r; |
| } |
| DNS_PACKET_HEADER(p)->nscount = htobe16(nscount); |
| |
| t->sent = TAKE_PTR(p); |
| return 0; |
| } |
| |
| static int dns_transaction_make_packet(DnsTransaction *t) { |
| _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
| int r; |
| |
| assert(t); |
| |
| if (t->scope->protocol == DNS_PROTOCOL_MDNS) |
| return dns_transaction_make_packet_mdns(t); |
| |
| if (t->sent) |
| return 0; |
| |
| if (t->bypass && t->bypass->protocol == t->scope->protocol) { |
| /* If bypass logic is enabled and the protocol if the original packet and our scope match, |
| * take the original packet, copy it, and patch in our new ID */ |
| r = dns_packet_dup(&p, t->bypass); |
| if (r < 0) |
| return r; |
| } else { |
| r = dns_packet_new_query( |
| &p, t->scope->protocol, |
| /* min_alloc_dsize = */ 0, |
| /* dnssec_cd = */ !FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) && |
| t->scope->dnssec_mode != DNSSEC_NO); |
| if (r < 0) |
| return r; |
| |
| r = dns_packet_append_key(p, dns_transaction_key(t), 0, NULL); |
| if (r < 0) |
| return r; |
| |
| DNS_PACKET_HEADER(p)->qdcount = htobe16(1); |
| } |
| |
| DNS_PACKET_HEADER(p)->id = t->id; |
| |
| t->sent = TAKE_PTR(p); |
| return 0; |
| } |
| |
| int dns_transaction_go(DnsTransaction *t) { |
| usec_t ts; |
| int r; |
| char key_str[DNS_RESOURCE_KEY_STRING_MAX]; |
| |
| assert(t); |
| |
| /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has |
| * finished now. In the latter case, the transaction and query candidate objects must not be accessed. |
| */ |
| |
| assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &ts) >= 0); |
| |
| r = dns_transaction_prepare(t, ts); |
| if (r <= 0) |
| return r; |
| |
| log_debug("Firing %s transaction %" PRIu16 " for <%s> scope %s on %s/%s (validate=%s).", |
| t->bypass ? "bypass" : "regular", |
| t->id, |
| dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str), |
| dns_protocol_to_string(t->scope->protocol), |
| t->scope->link ? t->scope->link->ifname : "*", |
| af_to_name_short(t->scope->family), |
| yes_no(!FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE))); |
| |
| if (!t->initial_jitter_scheduled && |
| IN_SET(t->scope->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) { |
| usec_t jitter; |
| |
| /* RFC 4795 Section 2.7 suggests all LLMNR queries should be delayed by a random time from 0 to |
| * JITTER_INTERVAL. |
| * RFC 6762 Section 8.1 suggests initial probe queries should be delayed by a random time from |
| * 0 to 250ms. */ |
| |
| t->initial_jitter_scheduled = true; |
| t->n_attempts = 0; |
| |
| switch (t->scope->protocol) { |
| |
| case DNS_PROTOCOL_LLMNR: |
| jitter = random_u64_range(LLMNR_JITTER_INTERVAL_USEC); |
| break; |
| |
| case DNS_PROTOCOL_MDNS: |
| if (t->probing) |
| jitter = random_u64_range(MDNS_PROBING_INTERVAL_USEC); |
| else |
| jitter = 0; |
| break; |
| default: |
| assert_not_reached(); |
| } |
| |
| r = dns_transaction_setup_timeout(t, jitter, ts); |
| if (r < 0) |
| return r; |
| |
| log_debug("Delaying %s transaction %" PRIu16 " for " USEC_FMT "us.", |
| dns_protocol_to_string(t->scope->protocol), |
| t->id, |
| jitter); |
| return 1; |
| } |
| |
| /* Otherwise, we need to ask the network */ |
| r = dns_transaction_make_packet(t); |
| if (r < 0) |
| return r; |
| |
| if (t->scope->protocol == DNS_PROTOCOL_LLMNR && |
| (dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), "in-addr.arpa") > 0 || |
| dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), "ip6.arpa") > 0)) { |
| |
| /* RFC 4795, Section 2.4. says reverse lookups shall |
| * always be made via TCP on LLMNR */ |
| r = dns_transaction_emit_tcp(t); |
| } else { |
| /* Try via UDP, and if that fails due to large size or lack of |
| * support try via TCP */ |
| r = dns_transaction_emit_udp(t); |
| if (r == -EMSGSIZE) |
| log_debug("Sending query via TCP since it is too large."); |
| else if (r == -EAGAIN) |
| log_debug("Sending query via TCP since UDP isn't supported or DNS-over-TLS is selected."); |
| else if (r == -EPERM) |
| log_debug("Sending query via TCP since UDP is blocked."); |
| if (IN_SET(r, -EMSGSIZE, -EAGAIN, -EPERM)) |
| r = dns_transaction_emit_tcp(t); |
| } |
| if (r == -ELOOP) { |
| if (t->scope->protocol != DNS_PROTOCOL_DNS) |
| return r; |
| |
| /* One of our own stub listeners */ |
| log_debug_errno(r, "Detected that specified DNS server is our own extra listener, switching DNS servers."); |
| |
| dns_scope_next_dns_server(t->scope, t->server); |
| |
| if (dns_scope_get_dns_server(t->scope) == t->server) { |
| log_debug_errno(r, "Still pointing to extra listener after switching DNS servers, refusing operation."); |
| dns_transaction_complete(t, DNS_TRANSACTION_STUB_LOOP); |
| return 0; |
| } |
| |
| return dns_transaction_go(t); |
| } |
| if (r == -ESRCH) { |
| /* No servers to send this to? */ |
| dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS); |
| return 0; |
| } |
| if (r == -EOPNOTSUPP) { |
| /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */ |
| dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED); |
| return 0; |
| } |
| if (t->scope->protocol == DNS_PROTOCOL_LLMNR && ERRNO_IS_DISCONNECT(r)) { |
| /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot |
| * answer this request with this protocol. */ |
| dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND); |
| return 0; |
| } |
| if (r < 0) { |
| if (t->scope->protocol != DNS_PROTOCOL_DNS) |
| return r; |
| |
| /* Couldn't send? Try immediately again, with a new server */ |
| dns_scope_next_dns_server(t->scope, t->server); |
| |
| return dns_transaction_go(t); |
| } |
| |
| usec_t timeout = transaction_get_resend_timeout(t); |
| r = dns_transaction_setup_timeout(t, timeout, usec_add(ts, timeout)); |
| if (r < 0) |
| return r; |
| |
| return 1; |
| } |
| |
| static int dns_transaction_find_cyclic(DnsTransaction *t, DnsTransaction *aux) { |
| DnsTransaction *n; |
| int r; |
| |
| assert(t); |
| assert(aux); |
| |
| /* Try to find cyclic dependencies between transaction objects */ |
| |
| if (t == aux) |
| return 1; |
| |
| SET_FOREACH(n, aux->dnssec_transactions) { |
| r = dns_transaction_find_cyclic(t, n); |
| if (r != 0) |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| static int dns_transaction_add_dnssec_transaction(DnsTransaction *t, DnsResourceKey *key, DnsTransaction **ret) { |
| _cleanup_(dns_transaction_gcp) DnsTransaction *aux = NULL; |
| int r; |
| |
| assert(t); |
| assert(ret); |
| assert(key); |
| |
| aux = dns_scope_find_transaction(t->scope, key, t->query_flags); |
| if (!aux) { |
| r = dns_transaction_new(&aux, t->scope, key, NULL, t->query_flags); |
| if (r < 0) |
| return r; |
| } else { |
| if (set_contains(t->dnssec_transactions, aux)) { |
| *ret = aux; |
| return 0; |
| } |
| |
| r = dns_transaction_find_cyclic(t, aux); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| char s[DNS_RESOURCE_KEY_STRING_MAX], saux[DNS_RESOURCE_KEY_STRING_MAX]; |
| |
| return log_debug_errno(SYNTHETIC_ERRNO(ELOOP), |
| "Potential cyclic dependency, refusing to add transaction %" PRIu16 " (%s) as dependency for %" PRIu16 " (%s).", |
| aux->id, |
| dns_resource_key_to_string(dns_transaction_key(t), s, sizeof s), |
| t->id, |
| dns_resource_key_to_string(dns_transaction_key(aux), saux, sizeof saux)); |
| } |
| } |
| |
| r = set_ensure_allocated(&aux->notify_transactions_done, NULL); |
| if (r < 0) |
| return r; |
| |
| r = set_ensure_put(&t->dnssec_transactions, NULL, aux); |
| if (r < 0) |
| return r; |
| |
| r = set_ensure_put(&aux->notify_transactions, NULL, t); |
| if (r < 0) { |
| (void) set_remove(t->dnssec_transactions, aux); |
| return r; |
| } |
| |
| *ret = TAKE_PTR(aux); |
| return 1; |
| } |
| |
| static int dns_transaction_request_dnssec_rr(DnsTransaction *t, DnsResourceKey *key) { |
| _cleanup_(dns_answer_unrefp) DnsAnswer *a = NULL; |
| DnsTransaction *aux; |
| int r; |
| |
| assert(t); |
| assert(key); |
| |
| /* Try to get the data from the trust anchor */ |
| r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, key, &a); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| r = dns_answer_extend(&t->validated_keys, a); |
| if (r < 0) |
| return r; |
| |
| return 0; |
| } |
| |
| /* This didn't work, ask for it via the network/cache then. */ |
| r = dns_transaction_add_dnssec_transaction(t, key, &aux); |
| if (r == -ELOOP) /* This would result in a cyclic dependency */ |
| return 0; |
| if (r < 0) |
| return r; |
| |
| if (aux->state == DNS_TRANSACTION_NULL) { |
| r = dns_transaction_go(aux); |
| if (r < 0) |
| return r; |
| } |
| |
| return 1; |
| } |
| |
| static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction *t, const char *name) { |
| int r; |
| |
| assert(t); |
| |
| /* Check whether the specified name is in the NTA |
| * database, either in the global one, or the link-local |
| * one. */ |
| |
| r = dns_trust_anchor_lookup_negative(&t->scope->manager->trust_anchor, name); |
| if (r != 0) |
| return r; |
| |
| if (!t->scope->link) |
| return 0; |
| |
| return link_negative_trust_anchor_lookup(t->scope->link, name); |
| } |
| |
| static int dns_transaction_has_negative_answer(DnsTransaction *t) { |
| int r; |
| |
| assert(t); |
| |
| /* Checks whether the answer is negative, and lacks NSEC/NSEC3 |
| * RRs to prove it */ |
| |
| r = dns_transaction_has_positive_answer(t, NULL); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| return false; |
| |
| /* Is this key explicitly listed as a negative trust anchor? |
| * If so, it's nothing we need to care about */ |
| r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(dns_transaction_key(t))); |
| if (r < 0) |
| return r; |
| return !r; |
| } |
| |
| static int dns_transaction_is_primary_response(DnsTransaction *t, DnsResourceRecord *rr) { |
| int r; |
| |
| assert(t); |
| assert(rr); |
| |
| /* Check if the specified RR is the "primary" response, |
| * i.e. either matches the question precisely or is a |
| * CNAME/DNAME for it. */ |
| |
| r = dns_resource_key_match_rr(dns_transaction_key(t), rr, NULL); |
| if (r != 0) |
| return r; |
| |
| return dns_resource_key_match_cname_or_dname(dns_transaction_key(t), rr->key, NULL); |
| } |
| |
| static bool dns_transaction_dnssec_supported(DnsTransaction *t) { |
| assert(t); |
| |
| /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon |
| * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */ |
| |
| if (t->scope->protocol != DNS_PROTOCOL_DNS) |
| return false; |
| |
| /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well |
| * be supported, hence return true. */ |
| if (!t->server) |
| return true; |
| |
| /* Note that we do not check the feature level actually used for the transaction but instead the feature level |
| * the server is known to support currently, as the transaction feature level might be lower than what the |
| * server actually supports, since we might have downgraded this transaction's feature level because we got a |
| * SERVFAIL earlier and wanted to check whether downgrading fixes it. */ |
| |
| return dns_server_dnssec_supported(t->server); |
| } |
| |
| static bool dns_transaction_dnssec_supported_full(DnsTransaction *t) { |
| DnsTransaction *dt; |
| |
| assert(t); |
| |
| /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */ |
| |
| if (!dns_transaction_dnssec_supported(t)) |
| return false; |
| |
| SET_FOREACH(dt, t->dnssec_transactions) |
| if (!dns_transaction_dnssec_supported(dt)) |
| return false; |
| |
| return true; |
| } |
| |
| int dns_transaction_request_dnssec_keys(DnsTransaction *t) { |
| DnsResourceRecord *rr; |
| |
| int r; |
| |
| assert(t); |
| |
| /* |
| * Retrieve all auxiliary RRs for the answer we got, so that |
| * we can verify signatures or prove that RRs are rightfully |
| * unsigned. Specifically: |
| * |
| * - For RRSIG we get the matching DNSKEY |
| * - For DNSKEY we get the matching DS |
| * - For unsigned SOA/NS we get the matching DS |
| * - For unsigned CNAME/DNAME/DS we get the parent SOA RR |
| * - For other unsigned RRs we get the matching SOA RR |
| * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR |
| * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR |
| * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR |
| */ |
| |
| if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) || t->scope->dnssec_mode == DNSSEC_NO) |
| return 0; |
| if (t->answer_source != DNS_TRANSACTION_NETWORK) |
| return 0; /* We only need to validate stuff from the network */ |
| if (!dns_transaction_dnssec_supported(t)) |
| return 0; /* If we can't do DNSSEC anyway there's no point in getting the auxiliary RRs */ |
| |
| DNS_ANSWER_FOREACH(rr, t->answer) { |
| |
| if (dns_type_is_pseudo(rr->key->type)) |
| continue; |
| |
| /* If this RR is in the negative trust anchor, we don't need to validate it. */ |
| r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key)); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| continue; |
| |
| switch (rr->key->type) { |
| |
| case DNS_TYPE_RRSIG: { |
| /* For each RRSIG we request the matching DNSKEY */ |
| _cleanup_(dns_resource_key_unrefp) DnsResourceKey *dnskey = NULL; |
| |
| /* If this RRSIG is about a DNSKEY RR and the |
| * signer is the same as the owner, then we |
| * already have the DNSKEY, and we don't have |
| * to look for more. */ |
| if (rr->rrsig.type_covered == DNS_TYPE_DNSKEY) { |
| r = dns_name_equal(rr->rrsig.signer, dns_resource_key_name(rr->key)); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| continue; |
| } |
| |
| /* If the signer is not a parent of our |
| * original query, then this is about an |
| * auxiliary RRset, but not anything we asked |
| * for. In this case we aren't interested, |
| * because we don't want to request additional |
| * RRs for stuff we didn't really ask for, and |
| * also to avoid request loops, where |
| * additional RRs from one transaction result |
| * in another transaction whose additional RRs |
| * point back to the original transaction, and |
| * we deadlock. */ |
| r = dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), rr->rrsig.signer); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| dnskey = dns_resource_key_new(rr->key->class, DNS_TYPE_DNSKEY, rr->rrsig.signer); |
| if (!dnskey) |
| return -ENOMEM; |
| |
| log_debug("Requesting DNSKEY to validate transaction %" PRIu16" (%s, RRSIG with key tag: %" PRIu16 ").", |
| t->id, dns_resource_key_name(rr->key), rr->rrsig.key_tag); |
| r = dns_transaction_request_dnssec_rr(t, dnskey); |
| if (r < 0) |
| return r; |
| break; |
| } |
| |
| case DNS_TYPE_DNSKEY: { |
| /* For each DNSKEY we request the matching DS */ |
| _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL; |
| |
| /* If the DNSKEY we are looking at is not for |
| * zone we are interested in, nor any of its |
| * parents, we aren't interested, and don't |
| * request it. After all, we don't want to end |
| * up in request loops, and want to keep |
| * additional traffic down. */ |
| |
| r = dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), dns_resource_key_name(rr->key)); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key)); |
| if (!ds) |
| return -ENOMEM; |
| |
| log_debug("Requesting DS to validate transaction %" PRIu16" (%s, DNSKEY with key tag: %" PRIu16 ").", |
| t->id, dns_resource_key_name(rr->key), dnssec_keytag(rr, false)); |
| r = dns_transaction_request_dnssec_rr(t, ds); |
| if (r < 0) |
| return r; |
| |
| break; |
| } |
| |
| case DNS_TYPE_SOA: |
| case DNS_TYPE_NS: { |
| _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL; |
| |
| /* For an unsigned SOA or NS, try to acquire |
| * the matching DS RR, as we are at a zone cut |
| * then, and whether a DS exists tells us |
| * whether the zone is signed. Do so only if |
| * this RR matches our original question, |
| * however. */ |
| |
| r = dns_resource_key_match_rr(dns_transaction_key(t), rr, NULL); |
| if (r < 0) |
| return r; |
| if (r == 0) { |
| /* Hmm, so this SOA RR doesn't match our original question. In this case, maybe this is |
| * a negative reply, and we need the SOA RR's TTL in order to cache a negative entry? |
| * If so, we need to validate it, too. */ |
| |
| r = dns_answer_match_key(t->answer, dns_transaction_key(t), NULL); |
| if (r < 0) |
| return r; |
| if (r > 0) /* positive reply, we won't need the SOA and hence don't need to validate |
| * it. */ |
| continue; |
| |
| /* Only bother with this if the SOA/NS RR we are looking at is actually a parent of |
| * what we are looking for, otherwise there's no value in it for us. */ |
| r = dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), dns_resource_key_name(rr->key)); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| } |
| |
| r = dnssec_has_rrsig(t->answer, rr->key); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| continue; |
| |
| ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key)); |
| if (!ds) |
| return -ENOMEM; |
| |
| log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned SOA/NS RRset).", |
| t->id, dns_resource_key_name(rr->key)); |
| r = dns_transaction_request_dnssec_rr(t, ds); |
| if (r < 0) |
| return r; |
| |
| break; |
| } |
| |
| case DNS_TYPE_DS: |
| case DNS_TYPE_CNAME: |
| case DNS_TYPE_DNAME: { |
| _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL; |
| const char *name; |
| |
| /* CNAMEs and DNAMEs cannot be located at a |
| * zone apex, hence ask for the parent SOA for |
| * unsigned CNAME/DNAME RRs, maybe that's the |
| * apex. But do all that only if this is |
| * actually a response to our original |
| * question. |
| * |
| * Similar for DS RRs, which are signed when |
| * the parent SOA is signed. */ |
| |
| r = dns_transaction_is_primary_response(t, rr); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| r = dnssec_has_rrsig(t->answer, rr->key); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| continue; |
| |
| r = dns_answer_has_dname_for_cname(t->answer, rr); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| continue; |
| |
| name = dns_resource_key_name(rr->key); |
| r = dns_name_parent(&name); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, name); |
| if (!soa) |
| return -ENOMEM; |
| |
| log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned CNAME/DNAME/DS RRset).", |
| t->id, dns_resource_key_name(rr->key)); |
| r = dns_transaction_request_dnssec_rr(t, soa); |
| if (r < 0) |
| return r; |
| |
| break; |
| } |
| |
| default: { |
| _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL; |
| |
| /* For other unsigned RRsets (including |
| * NSEC/NSEC3!), look for proof the zone is |
| * unsigned, by requesting the SOA RR of the |
| * zone. However, do so only if they are |
| * directly relevant to our original |
| * question. */ |
| |
| r = dns_transaction_is_primary_response(t, rr); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| r = dnssec_has_rrsig(t->answer, rr->key); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| continue; |
| |
| soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, dns_resource_key_name(rr->key)); |
| if (!soa) |
| return -ENOMEM; |
| |
| log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned non-SOA/NS RRset <%s>).", |
| t->id, dns_resource_key_name(rr->key), dns_resource_record_to_string(rr)); |
| r = dns_transaction_request_dnssec_rr(t, soa); |
| if (r < 0) |
| return r; |
| break; |
| }} |
| } |
| |
| /* Above, we requested everything necessary to validate what |
| * we got. Now, let's request what we need to validate what we |
| * didn't get... */ |
| |
| r = dns_transaction_has_negative_answer(t); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| const char *name, *signed_status; |
| uint16_t type = 0; |
| |
| name = dns_resource_key_name(dns_transaction_key(t)); |
| signed_status = dns_answer_contains_nsec_or_nsec3(t->answer) ? "signed" : "unsigned"; |
| |
| /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this |
| * could also be used as indication that we are not at a zone apex, but in real world setups there are |
| * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even |
| * though they have further children. If this was a DS request, then it's signed when the parent zone |
| * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR, |
| * to see if that is signed. */ |
| |
| if (dns_transaction_key(t)->type == DNS_TYPE_DS) { |
| r = dns_name_parent(&name); |
| if (r > 0) { |
| type = DNS_TYPE_SOA; |
| log_debug("Requesting parent SOA (%s %s) to validate transaction %" PRIu16 " (%s, %s empty DS response).", |
| special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), name, t->id, |
| dns_resource_key_name(dns_transaction_key(t)), signed_status); |
| } else |
| name = NULL; |
| |
| } else if (IN_SET(dns_transaction_key(t)->type, DNS_TYPE_SOA, DNS_TYPE_NS)) { |
| |
| type = DNS_TYPE_DS; |
| log_debug("Requesting DS (%s %s) to validate transaction %" PRIu16 " (%s, %s empty SOA/NS response).", |
| special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), name, t->id, name, signed_status); |
| |
| } else { |
| type = DNS_TYPE_SOA; |
| log_debug("Requesting SOA (%s %s) to validate transaction %" PRIu16 " (%s, %s empty non-SOA/NS/DS response).", |
| special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), name, t->id, name, signed_status); |
| } |
| |
| if (name) { |
| _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL; |
| |
| soa = dns_resource_key_new(dns_transaction_key(t)->class, type, name); |
| if (!soa) |
| return -ENOMEM; |
| |
| r = dns_transaction_request_dnssec_rr(t, soa); |
| if (r < 0) |
| return r; |
| } |
| } |
| |
| return dns_transaction_dnssec_is_live(t); |
| } |
| |
| void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source) { |
| assert(t); |
| assert(source); |
| |
| /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING, |
| we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If |
| the state is VALIDATING however, we should check if we are complete now. */ |
| |
| if (t->state == DNS_TRANSACTION_VALIDATING) |
| dns_transaction_process_dnssec(t); |
| } |
| |
| static int dns_transaction_validate_dnskey_by_ds(DnsTransaction *t) { |
| DnsAnswerItem *item; |
| int r; |
| |
| assert(t); |
| |
| /* Add all DNSKEY RRs from the answer that are validated by DS |
| * RRs from the list of validated keys to the list of |
| * validated keys. */ |
| |
| DNS_ANSWER_FOREACH_ITEM(item, t->answer) { |
| |
| r = dnssec_verify_dnskey_by_ds_search(item->rr, t->validated_keys); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| /* If so, the DNSKEY is validated too. */ |
| r = dns_answer_add_extend(&t->validated_keys, item->rr, item->ifindex, item->flags|DNS_ANSWER_AUTHENTICATED, item->rrsig); |
| if (r < 0) |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| static int dns_transaction_requires_rrsig(DnsTransaction *t, DnsResourceRecord *rr) { |
| int r; |
| |
| assert(t); |
| assert(rr); |
| |
| /* Checks if the RR we are looking for must be signed with an |
| * RRSIG. This is used for positive responses. */ |
| |
| if (t->scope->dnssec_mode == DNSSEC_NO) |
| return false; |
| |
| if (dns_type_is_pseudo(rr->key->type)) |
| return -EINVAL; |
| |
| r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key)); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| return false; |
| |
| switch (rr->key->type) { |
| |
| case DNS_TYPE_RRSIG: |
| /* RRSIGs are the signatures themselves, they need no signing. */ |
| return false; |
| |
| case DNS_TYPE_SOA: |
| case DNS_TYPE_NS: { |
| DnsTransaction *dt; |
| |
| /* For SOA or NS RRs we look for a matching DS transaction */ |
| |
| SET_FOREACH(dt, t->dnssec_transactions) { |
| |
| if (dns_transaction_key(dt)->class != rr->key->class) |
| continue; |
| if (dns_transaction_key(dt)->type != DNS_TYPE_DS) |
| continue; |
| |
| r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), dns_resource_key_name(rr->key)); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| /* We found a DS transactions for the SOA/NS |
| * RRs we are looking at. If it discovered signed DS |
| * RRs, then we need to be signed, too. */ |
| |
| if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) |
| return false; |
| |
| return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL); |
| } |
| |
| /* We found nothing that proves this is safe to leave |
| * this unauthenticated, hence ask inist on |
| * authentication. */ |
| return true; |
| } |
| |
| case DNS_TYPE_DS: |
| case DNS_TYPE_CNAME: |
| case DNS_TYPE_DNAME: { |
| const char *parent = NULL; |
| DnsTransaction *dt; |
| |
| /* |
| * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA. |
| * |
| * DS RRs are signed if the parent is signed, hence also look at the parent SOA |
| */ |
| |
| SET_FOREACH(dt, t->dnssec_transactions) { |
| |
| if (dns_transaction_key(dt)->class != rr->key->class) |
| continue; |
| if (dns_transaction_key(dt)->type != DNS_TYPE_SOA) |
| continue; |
| |
| if (!parent) { |
| parent = dns_resource_key_name(rr->key); |
| r = dns_name_parent(&parent); |
| if (r < 0) |
| return r; |
| if (r == 0) { |
| if (rr->key->type == DNS_TYPE_DS) |
| return true; |
| |
| /* A CNAME/DNAME without a parent? That's sooo weird. */ |
| return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG), |
| "Transaction %" PRIu16 " claims CNAME/DNAME at root. Refusing.", t->id); |
| } |
| } |
| |
| r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), parent); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| return FLAGS_SET(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED); |
| } |
| |
| return true; |
| } |
| |
| default: { |
| DnsTransaction *dt; |
| |
| /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */ |
| |
| SET_FOREACH(dt, t->dnssec_transactions) { |
| |
| if (dns_transaction_key(dt)->class != rr->key->class) |
| continue; |
| if (dns_transaction_key(dt)->type != DNS_TYPE_SOA) |
| continue; |
| |
| r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), dns_resource_key_name(rr->key)); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| /* We found the transaction that was supposed to find the SOA RR for us. It was |
| * successful, but found no RR for us. This means we are not at a zone cut. In this |
| * case, we require authentication if the SOA lookup was authenticated too. */ |
| return FLAGS_SET(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED); |
| } |
| |
| return true; |
| }} |
| } |
| |
| static int dns_transaction_in_private_tld(DnsTransaction *t, const DnsResourceKey *key) { |
| DnsTransaction *dt; |
| const char *tld; |
| int r; |
| |
| /* If DNSSEC downgrade mode is on, checks whether the |
| * specified RR is one level below a TLD we have proven not to |
| * exist. In such a case we assume that this is a private |
| * domain, and permit it. |
| * |
| * This detects cases like the Fritz!Box router networks. Each |
| * Fritz!Box router serves a private "fritz.box" zone, in the |
| * non-existing TLD "box". Requests for the "fritz.box" domain |
| * are served by the router itself, while requests for the |
| * "box" domain will result in NXDOMAIN. |
| * |
| * Note that this logic is unable to detect cases where a |
| * router serves a private DNS zone directly under |
| * non-existing TLD. In such a case we cannot detect whether |
| * the TLD is supposed to exist or not, as all requests we |
| * make for it will be answered by the router's zone, and not |
| * by the root zone. */ |
| |
| assert(t); |
| |
| if (t->scope->dnssec_mode != DNSSEC_ALLOW_DOWNGRADE) |
| return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */ |
| |
| tld = dns_resource_key_name(key); |
| r = dns_name_parent(&tld); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| return false; /* Already the root domain */ |
| |
| if (!dns_name_is_single_label(tld)) |
| return false; |
| |
| SET_FOREACH(dt, t->dnssec_transactions) { |
| |
| if (dns_transaction_key(dt)->class != key->class) |
| continue; |
| |
| r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), tld); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| /* We found an auxiliary lookup we did for the TLD. If |
| * that returned with NXDOMAIN, we know the TLD didn't |
| * exist, and hence this might be a private zone. */ |
| |
| return dt->answer_rcode == DNS_RCODE_NXDOMAIN; |
| } |
| |
| return false; |
| } |
| |
| static int dns_transaction_requires_nsec(DnsTransaction *t) { |
| char key_str[DNS_RESOURCE_KEY_STRING_MAX]; |
| DnsTransaction *dt; |
| const char *name; |
| uint16_t type = 0; |
| int r; |
| |
| assert(t); |
| |
| /* Checks if we need to insist on NSEC/NSEC3 RRs for proving |
| * this negative reply */ |
| |
| if (t->scope->dnssec_mode == DNSSEC_NO) |
| return false; |
| |
| if (dns_type_is_pseudo(dns_transaction_key(t)->type)) |
| return -EINVAL; |
| |
| r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(dns_transaction_key(t))); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| return false; |
| |
| r = dns_transaction_in_private_tld(t, dns_transaction_key(t)); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| /* The lookup is from a TLD that is proven not to |
| * exist, and we are in downgrade mode, hence ignore |
| * that fact that we didn't get any NSEC RRs. */ |
| |
| log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.", |
| dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str)); |
| return false; |
| } |
| |
| name = dns_resource_key_name(dns_transaction_key(t)); |
| |
| if (dns_transaction_key(t)->type == DNS_TYPE_DS) { |
| |
| /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed, |
| * hence check the parent SOA in this case. */ |
| |
| r = dns_name_parent(&name); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| return true; |
| |
| type = DNS_TYPE_SOA; |
| |
| } else if (IN_SET(dns_transaction_key(t)->type, DNS_TYPE_SOA, DNS_TYPE_NS)) |
| /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */ |
| type = DNS_TYPE_DS; |
| else |
| /* For all other negative replies, check for the SOA lookup */ |
| type = DNS_TYPE_SOA; |
| |
| /* For all other RRs we check the SOA on the same level to see |
| * if it's signed. */ |
| |
| SET_FOREACH(dt, t->dnssec_transactions) { |
| |
| if (dns_transaction_key(dt)->class != dns_transaction_key(t)->class) |
| continue; |
| if (dns_transaction_key(dt)->type != type) |
| continue; |
| |
| r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), name); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| return FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED); |
| } |
| |
| /* If in doubt, require NSEC/NSEC3 */ |
| return true; |
| } |
| |
| static int dns_transaction_dnskey_authenticated(DnsTransaction *t, DnsResourceRecord *rr) { |
| DnsResourceRecord *rrsig; |
| bool found = false; |
| int r; |
| |
| /* Checks whether any of the DNSKEYs used for the RRSIGs for |
| * the specified RRset is authenticated (i.e. has a matching |
| * DS RR). */ |
| |
| r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key)); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| return false; |
| |
| DNS_ANSWER_FOREACH(rrsig, t->answer) { |
| DnsTransaction *dt; |
| |
| r = dnssec_key_match_rrsig(rr->key, rrsig); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| SET_FOREACH(dt, t->dnssec_transactions) { |
| |
| if (dns_transaction_key(dt)->class != rr->key->class) |
| continue; |
| |
| if (dns_transaction_key(dt)->type == DNS_TYPE_DNSKEY) { |
| |
| r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), rrsig->rrsig.signer); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| /* OK, we found an auxiliary DNSKEY lookup. If that lookup is authenticated, |
| * report this. */ |
| |
| if (FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) |
| return true; |
| |
| found = true; |
| |
| } else if (dns_transaction_key(dt)->type == DNS_TYPE_DS) { |
| |
| r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), rrsig->rrsig.signer); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| continue; |
| |
| /* OK, we found an auxiliary DS lookup. If that lookup is authenticated and |
| * non-zero, we won! */ |
| |
| if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) |
| return false; |
| |
| return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL); |
| } |
| } |
| } |
| |
| return found ? false : -ENXIO; |
| } |
| |
| static int dns_transaction_known_signed(DnsTransaction *t, DnsResourceRecord *rr) { |
| assert(t); |
| assert(rr); |
| |
| /* We know that the root domain is signed, hence if it appears |
| * not to be signed, there's a problem with the DNS server */ |
| |
| return rr->key->class == DNS_CLASS_IN && |
| dns_name_is_root(dns_resource_key_name(rr->key)); |
| } |
| |
| static int dns_transaction_check_revoked_trust_anchors(DnsTransaction *t) { |
| DnsResourceRecord *rr; |
| int r; |
| |
| assert(t); |
| |
| /* Maybe warn the user that we encountered a revoked DNSKEY |
| * for a key from our trust anchor. Note that we don't care |
| * whether the DNSKEY can be authenticated or not. It's |
| * sufficient if it is self-signed. */ |
| |
| DNS_ANSWER_FOREACH(rr, t->answer) { |
| r = dns_trust_anchor_check_revoked(&t->scope->manager->trust_anchor, rr, t->answer); |
| if (r < 0) |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| static int dns_transaction_invalidate_revoked_keys(DnsTransaction *t) { |
| bool changed; |
| int r; |
| |
| assert(t); |
| |
| /* Removes all DNSKEY/DS objects from t->validated_keys that |
| * our trust anchors database considers revoked. */ |
| |
| do { |
| DnsResourceRecord *rr; |
| |
| changed = false; |
| |
| DNS_ANSWER_FOREACH(rr, t->validated_keys) { |
| r = dns_trust_anchor_is_revoked(&t->scope->manager->trust_anchor, rr); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| r = dns_answer_remove_by_rr(&t->validated_keys, rr); |
| if (r < 0) |
| return r; |
| |
| assert(r > 0); |
| changed = true; |
| break; |
| } |
| } |
| } while (changed); |
| |
| return 0; |
| } |
| |
| static int dns_transaction_copy_validated(DnsTransaction *t) { |
| DnsTransaction *dt; |
| int r; |
| |
| assert(t); |
| |
| /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */ |
| |
| SET_FOREACH(dt, t->dnssec_transactions) { |
| |
| if (DNS_TRANSACTION_IS_LIVE(dt->state)) |
| continue; |
| |
| if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) |
| continue; |
| |
| r = dns_answer_extend(&t->validated_keys, dt->answer); |
| if (r < 0) |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| typedef enum { |
| DNSSEC_PHASE_DNSKEY, /* Phase #1, only validate DNSKEYs */ |
| DNSSEC_PHASE_NSEC, /* Phase #2, only validate NSEC+NSEC3 */ |
| DNSSEC_PHASE_ALL, /* Phase #3, validate everything else */ |
| } Phase; |
| |
| static int dnssec_validate_records( |
| DnsTransaction *t, |
| Phase phase, |
| bool *have_nsec, |
| DnsAnswer **validated) { |
| |
| DnsResourceRecord *rr; |
| int r; |
| |
| /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */ |
| |
| DNS_ANSWER_FOREACH(rr, t->answer) { |
| _unused_ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr_ref = dns_resource_record_ref(rr); |
| DnsResourceRecord *rrsig = NULL; |
| DnssecResult result; |
| |
| switch (rr->key->type) { |
| case DNS_TYPE_RRSIG: |
| continue; |
| |
| case DNS_TYPE_DNSKEY: |
| /* We validate DNSKEYs only in the DNSKEY and ALL phases */ |
| if (phase == DNSSEC_PHASE_NSEC) |
| continue; |
| break; |
| |
| case DNS_TYPE_NSEC: |
| case DNS_TYPE_NSEC3: |
| *have_nsec = true; |
| |
| /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */ |
| if (phase == DNSSEC_PHASE_DNSKEY) |
| continue; |
| break; |
| |
| default: |
| /* We validate all other RRs only in the ALL phases */ |
| if (phase != DNSSEC_PHASE_ALL) |
| continue; |
| } |
| |
| r = dnssec_verify_rrset_search( |
| t->answer, |
| rr->key, |
| t->validated_keys, |
| USEC_INFINITY, |
| &result, |
| &rrsig); |
| if (r < 0) |
| return r; |
| |
| log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr)), dnssec_result_to_string(result)); |
| |
| if (result == DNSSEC_VALIDATED) { |
| assert(rrsig); |
| |
| if (rr->key->type == DNS_TYPE_DNSKEY) { |
| /* If we just validated a DNSKEY RRset, then let's add these keys to |
| * the set of validated keys for this transaction. */ |
| |
| r = dns_answer_copy_by_key(&t->validated_keys, t->answer, rr->key, DNS_ANSWER_AUTHENTICATED, rrsig); |
| if (r < 0) |
| return r; |
| |
| /* Some of the DNSKEYs we just added might already have been revoked, |
| * remove them again in that case. */ |
| r = dns_transaction_invalidate_revoked_keys(t); |
| if (r < 0) |
| return r; |
| } |
| |
| /* Add the validated RRset to the new list of validated RRsets, and remove it from |
| * the unvalidated RRsets. We mark the RRset as authenticated and cacheable. */ |
| r = dns_answer_move_by_key(validated, &t->answer, rr->key, DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE, rrsig); |
| if (r < 0) |
| return r; |
| |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_SECURE, rr->key); |
| |
| /* Exit the loop, we dropped something from the answer, start from the beginning */ |
| return 1; |
| } |
| |
| /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as |
| * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet, |
| * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */ |
| if (phase != DNSSEC_PHASE_ALL) |
| continue; |
| |
| if (result == DNSSEC_VALIDATED_WILDCARD) { |
| bool authenticated = false; |
| const char *source; |
| |
| assert(rrsig); |
| |
| /* This RRset validated, but as a wildcard. This means we need |
| * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists. */ |
| |
| /* First step, determine the source of synthesis */ |
| r = dns_resource_record_source(rrsig, &source); |
| if (r < 0) |
| return r; |
| |
| r = dnssec_test_positive_wildcard(*validated, |
| dns_resource_key_name(rr->key), |
| source, |
| rrsig->rrsig.signer, |
| &authenticated); |
| |
| /* Unless the NSEC proof showed that the key really doesn't exist something is off. */ |
| if (r == 0) |
| result = DNSSEC_INVALID; |
| else { |
| r = dns_answer_move_by_key( |
| validated, |
| &t->answer, |
| rr->key, |
| authenticated ? (DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE) : 0, |
| rrsig); |
| if (r < 0) |
| return r; |
| |
| manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, rr->key); |
| |
| /* Exit the loop, we dropped something from the answer, start from the beginning */ |
| return 1; |
| } |
| } |
| |
| if (result == DNSSEC_NO_SIGNATURE) { |
| r = dns_transaction_requires_rrsig(t, rr); |
| if (r < 0) |
| return r; |
| if (r == 0) { |
| /* Data does not require signing. In that case, just copy it over, |
| * but remember that this is by no means authenticated. */ |
| r = dns_answer_move_by_key( |
| validated, |
| &t->answer, |
| rr->key, |
| 0, |
| NULL); |
| if (r < 0) |
| return r; |
| |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); |
| return 1; |
| } |
| |
| r = dns_transaction_known_signed(t, rr); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| /* This is an RR we know has to be signed. If it isn't this means |
| * the server is not attaching RRSIGs, hence complain. */ |
| |
| dns_server_packet_rrsig_missing(t->server, t->current_feature_level); |
| |
| if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) { |
| |
| /* Downgrading is OK? If so, just consider the information unsigned */ |
| |
| r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL); |
| if (r < 0) |
| return r; |
| |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); |
| return 1; |
| } |
| |
| /* Otherwise, fail */ |
| t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER; |
| return 0; |
| } |
| |
| r = dns_transaction_in_private_tld(t, rr->key); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| char s[DNS_RESOURCE_KEY_STRING_MAX]; |
| |
| /* The data is from a TLD that is proven not to exist, and we are in downgrade |
| * mode, hence ignore the fact that this was not signed. */ |
| |
| log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.", |
| dns_resource_key_to_string(rr->key, s, sizeof s)); |
| |
| r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL); |
| if (r < 0) |
| return r; |
| |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); |
| return 1; |
| } |
| } |
| |
| /* https://datatracker.ietf.org/doc/html/rfc6840#section-5.2 */ |
| if (result == DNSSEC_UNSUPPORTED_ALGORITHM) { |
| r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL); |
| if (r < 0) |
| return r; |
| |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); |
| return 1; |
| } |
| |
| if (IN_SET(result, |
| DNSSEC_MISSING_KEY, |
| DNSSEC_SIGNATURE_EXPIRED)) { |
| |
| r = dns_transaction_dnskey_authenticated(t, rr); |
| if (r < 0 && r != -ENXIO) |
| return r; |
| if (r == 0) { |
| /* The DNSKEY transaction was not authenticated, this means there's |
| * no DS for this, which means it's OK if no keys are found for this signature. */ |
| |
| r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL); |
| if (r < 0) |
| return r; |
| |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key); |
| return 1; |
| } |
| } |
| |
| r = dns_transaction_is_primary_response(t, rr); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| /* Look for a matching DNAME for this CNAME */ |
| r = dns_answer_has_dname_for_cname(t->answer, rr); |
| if (r < 0) |
| return r; |
| if (r == 0) { |
| /* Also look among the stuff we already validated */ |
| r = dns_answer_has_dname_for_cname(*validated, rr); |
| if (r < 0) |
| return r; |
| } |
| |
| if (r == 0) { |
| if (IN_SET(result, |
| DNSSEC_INVALID, |
| DNSSEC_SIGNATURE_EXPIRED, |
| DNSSEC_NO_SIGNATURE)) |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, rr->key); |
| else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */ |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, rr->key); |
| |
| /* This is a primary response to our question, and it failed validation. |
| * That's fatal. */ |
| t->answer_dnssec_result = result; |
| return 0; |
| } |
| |
| /* This is a primary response, but we do have a DNAME RR |
| * in the RR that can replay this CNAME, hence rely on |
| * that, and we can remove the CNAME in favour of it. */ |
| } |
| |
| /* This is just some auxiliary data. Just remove the RRset and continue. */ |
| r = dns_answer_remove_by_key(&t->answer, rr->key); |
| if (r < 0) |
| return r; |
| |
| /* We dropped something from the answer, start from the beginning. */ |
| return 1; |
| } |
| |
| return 2; /* Finito. */ |
| } |
| |
| int dns_transaction_validate_dnssec(DnsTransaction *t) { |
| _cleanup_(dns_answer_unrefp) DnsAnswer *validated = NULL; |
| Phase phase; |
| DnsAnswerFlags flags; |
| int r; |
| char key_str[DNS_RESOURCE_KEY_STRING_MAX]; |
| |
| assert(t); |
| |
| /* We have now collected all DS and DNSKEY RRs in t->validated_keys, let's see which RRs we can now |
| * authenticate with that. */ |
| |
| if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) || t->scope->dnssec_mode == DNSSEC_NO) |
| return 0; |
| |
| /* Already validated */ |
| if (t->answer_dnssec_result != _DNSSEC_RESULT_INVALID) |
| return 0; |
| |
| /* Our own stuff needs no validation */ |
| if (IN_SET(t->answer_source, DNS_TRANSACTION_ZONE, DNS_TRANSACTION_TRUST_ANCHOR)) { |
| t->answer_dnssec_result = DNSSEC_VALIDATED; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, true); |
| return 0; |
| } |
| |
| /* Cached stuff is not affected by validation. */ |
| if (t->answer_source != DNS_TRANSACTION_NETWORK) |
| return 0; |
| |
| if (!dns_transaction_dnssec_supported_full(t)) { |
| /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */ |
| t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER; |
| log_debug("Not validating response for %" PRIu16 ", used server feature level does not support DNSSEC.", t->id); |
| return 0; |
| } |
| |
| log_debug("Validating response from transaction %" PRIu16 " (%s).", |
| t->id, |
| dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str)); |
| |
| /* First, see if this response contains any revoked trust |
| * anchors we care about */ |
| r = dns_transaction_check_revoked_trust_anchors(t); |
| if (r < 0) |
| return r; |
| |
| /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */ |
| r = dns_transaction_copy_validated(t); |
| if (r < 0) |
| return r; |
| |
| /* Second, see if there are DNSKEYs we already know a |
| * validated DS for. */ |
| r = dns_transaction_validate_dnskey_by_ds(t); |
| if (r < 0) |
| return r; |
| |
| /* Fourth, remove all DNSKEY and DS RRs again that our trust |
| * anchor says are revoked. After all we might have marked |
| * some keys revoked above, but they might still be lingering |
| * in our validated_keys list. */ |
| r = dns_transaction_invalidate_revoked_keys(t); |
| if (r < 0) |
| return r; |
| |
| phase = DNSSEC_PHASE_DNSKEY; |
| for (;;) { |
| bool have_nsec = false; |
| |
| r = dnssec_validate_records(t, phase, &have_nsec, &validated); |
| if (r <= 0) |
| return r; |
| |
| /* Try again as long as we managed to achieve something */ |
| if (r == 1) |
| continue; |
| |
| if (phase == DNSSEC_PHASE_DNSKEY && have_nsec) { |
| /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */ |
| phase = DNSSEC_PHASE_NSEC; |
| continue; |
| } |
| |
| if (phase != DNSSEC_PHASE_ALL) { |
| /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now. |
| * Note that in this third phase we start to remove RRs we couldn't validate. */ |
| phase = DNSSEC_PHASE_ALL; |
| continue; |
| } |
| |
| /* We're done */ |
| break; |
| } |
| |
| DNS_ANSWER_REPLACE(t->answer, TAKE_PTR(validated)); |
| |
| /* At this point the answer only contains validated |
| * RRsets. Now, let's see if it actually answers the question |
| * we asked. If so, great! If it doesn't, then see if |
| * NSEC/NSEC3 can prove this. */ |
| r = dns_transaction_has_positive_answer(t, &flags); |
| if (r > 0) { |
| /* Yes, it answers the question! */ |
| |
| if (flags & DNS_ANSWER_AUTHENTICATED) { |
| /* The answer is fully authenticated, yay. */ |
| t->answer_dnssec_result = DNSSEC_VALIDATED; |
| t->answer_rcode = DNS_RCODE_SUCCESS; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, true); |
| } else { |
| /* The answer is not fully authenticated. */ |
| t->answer_dnssec_result = DNSSEC_UNSIGNED; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); |
| } |
| |
| } else if (r == 0) { |
| DnssecNsecResult nr; |
| bool authenticated = false; |
| |
| /* Bummer! Let's check NSEC/NSEC3 */ |
| r = dnssec_nsec_test(t->answer, dns_transaction_key(t), &nr, &authenticated, &t->answer_nsec_ttl); |
| if (r < 0) |
| return r; |
| |
| switch (nr) { |
| |
| case DNSSEC_NSEC_NXDOMAIN: |
| /* NSEC proves the domain doesn't exist. Very good. */ |
| log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str); |
| t->answer_dnssec_result = DNSSEC_VALIDATED; |
| t->answer_rcode = DNS_RCODE_NXDOMAIN; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, authenticated); |
| |
| manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, dns_transaction_key(t)); |
| break; |
| |
| case DNSSEC_NSEC_NODATA: |
| /* NSEC proves that there's no data here, very good. */ |
| log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str); |
| t->answer_dnssec_result = DNSSEC_VALIDATED; |
| t->answer_rcode = DNS_RCODE_SUCCESS; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, authenticated); |
| |
| manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, dns_transaction_key(t)); |
| break; |
| |
| case DNSSEC_NSEC_OPTOUT: |
| /* NSEC3 says the data might not be signed */ |
| log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str); |
| t->answer_dnssec_result = DNSSEC_UNSIGNED; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); |
| |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, dns_transaction_key(t)); |
| break; |
| |
| case DNSSEC_NSEC_NO_RR: |
| /* No NSEC data? Bummer! */ |
| |
| r = dns_transaction_requires_nsec(t); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| t->answer_dnssec_result = DNSSEC_NO_SIGNATURE; |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, dns_transaction_key(t)); |
| } else { |
| t->answer_dnssec_result = DNSSEC_UNSIGNED; |
| SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false); |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, dns_transaction_key(t)); |
| } |
| |
| break; |
| |
| case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM: |
| /* We don't know the NSEC3 algorithm used? */ |
| t->answer_dnssec_result = DNSSEC_UNSUPPORTED_ALGORITHM; |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, dns_transaction_key(t)); |
| break; |
| |
| case DNSSEC_NSEC_FOUND: |
| case DNSSEC_NSEC_CNAME: |
| /* NSEC says it needs to be there, but we couldn't find it? Bummer! */ |
| t->answer_dnssec_result = DNSSEC_NSEC_MISMATCH; |
| manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, dns_transaction_key(t)); |
| break; |
| |
| default: |
| assert_not_reached(); |
| } |
| } |
| |
| return 1; |
| } |
| |
| static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] = { |
| [DNS_TRANSACTION_NULL] = "null", |
| [DNS_TRANSACTION_PENDING] = "pending", |
| [DNS_TRANSACTION_VALIDATING] = "validating", |
| [DNS_TRANSACTION_RCODE_FAILURE] = "rcode-failure", |
| [DNS_TRANSACTION_SUCCESS] = "success", |
| [DNS_TRANSACTION_NO_SERVERS] = "no-servers", |
| [DNS_TRANSACTION_TIMEOUT] = "timeout", |
| [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED] = "attempts-max-reached", |
| [DNS_TRANSACTION_INVALID_REPLY] = "invalid-reply", |
| [DNS_TRANSACTION_ERRNO] = "errno", |
| [DNS_TRANSACTION_ABORTED] = "aborted", |
| [DNS_TRANSACTION_DNSSEC_FAILED] = "dnssec-failed", |
| [DNS_TRANSACTION_NO_TRUST_ANCHOR] = "no-trust-anchor", |
| [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED] = "rr-type-unsupported", |
| [DNS_TRANSACTION_NETWORK_DOWN] = "network-down", |
| [DNS_TRANSACTION_NOT_FOUND] = "not-found", |
| [DNS_TRANSACTION_NO_SOURCE] = "no-source", |
| [DNS_TRANSACTION_STUB_LOOP] = "stub-loop", |
| }; |
| DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state, DnsTransactionState); |
| |
| static const char* const dns_transaction_source_table[_DNS_TRANSACTION_SOURCE_MAX] = { |
| [DNS_TRANSACTION_NETWORK] = "network", |
| [DNS_TRANSACTION_CACHE] = "cache", |
| [DNS_TRANSACTION_ZONE] = "zone", |
| [DNS_TRANSACTION_TRUST_ANCHOR] = "trust-anchor", |
| }; |
| DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source, DnsTransactionSource); |