diff options
Diffstat (limited to 'src/resolve/resolved-dns-transaction.c')
-rw-r--r-- | src/resolve/resolved-dns-transaction.c | 3106 |
1 files changed, 0 insertions, 3106 deletions
diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c deleted file mode 100644 index 2fce44ec8b..0000000000 --- a/src/resolve/resolved-dns-transaction.c +++ /dev/null @@ -1,3106 +0,0 @@ -/*** - This file is part of systemd. - - Copyright 2014 Lennart Poettering - - systemd is free software; you can redistribute it and/or modify it - under the terms of the GNU Lesser General Public License as published by - the Free Software Foundation; either version 2.1 of the License, or - (at your option) any later version. - - systemd is distributed in the hope that it will be useful, but - WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public License - along with systemd; If not, see <http://www.gnu.org/licenses/>. -***/ - -#include <sd-messages.h> - -#include "af-list.h" -#include "alloc-util.h" -#include "dns-domain.h" -#include "errno-list.h" -#include "fd-util.h" -#include "random-util.h" -#include "resolved-dns-cache.h" -#include "resolved-dns-transaction.h" -#include "resolved-llmnr.h" -#include "string-table.h" - -#define TRANSACTIONS_MAX 4096 - -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_authenticated = false; - t->answer_nsec_ttl = (uint32_t) -1; - 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) { - assert(t); - - if (t->stream) { - /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */ - t->stream->complete = NULL; - t->stream->on_packet = NULL; - t->stream->transaction = NULL; - t->stream = dns_stream_unref(t->stream); - } - - t->dns_udp_event_source = sd_event_source_unref(t->dns_udp_event_source); - 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_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); - dns_transaction_stop_timeout(t); - - dns_packet_unref(t->sent); - dns_transaction_reset_answer(t); - - dns_server_unref(t->server); - - if (t->scope) { - hashmap_remove_value(t->scope->transactions_by_key, t->key, t); - 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); - - return mfree(t); -} - -DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free); - -bool dns_transaction_gc(DnsTransaction *t) { - assert(t); - - if (t->block_gc > 0) - return true; - - 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)) { - dns_transaction_free(t); - return false; - } - - return true; -} - -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; -} - -int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) { - _cleanup_(dns_transaction_freep) DnsTransaction *t = NULL; - int r; - - assert(ret); - assert(s); - assert(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 (key->class != DNS_CLASS_IN && key->class != DNS_CLASS_ANY) - return -EOPNOTSUPP; - - 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; - - r = hashmap_ensure_allocated(&s->transactions_by_key, &dns_resource_key_hash_ops); - if (r < 0) - return r; - - t = new0(DnsTransaction, 1); - if (!t) - return -ENOMEM; - - t->dns_udp_fd = -1; - t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID; - t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; - t->answer_nsec_ttl = (uint32_t) -1; - t->key = dns_resource_key_ref(key); - t->current_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID; - t->clamp_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID; - - t->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; - } - - r = hashmap_replace(s->transactions_by_key, t->key, t); - if (r < 0) { - hashmap_remove(s->manager->dns_transactions, UINT_TO_PTR(t->id)); - return r; - } - - LIST_PREPEND(transactions_by_scope, s->transactions, t); - t->scope = s; - - s->manager->n_transactions_total++; - - if (ret) - *ret = t; - - t = NULL; - - 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) { - _cleanup_free_ char *pretty = NULL; - char key_str[DNS_RESOURCE_KEY_STRING_MAX]; - DnsZoneItem *z; - - assert(t); - assert(p); - - if (manager_our_packet(t->scope->manager, p) != 0) - return; - - (void) in_addr_to_string(p->family, &p->sender, &pretty); - - log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s got tentative packet from %s.", - t->id, - dns_resource_key_to_string(t->key, key_str, sizeof key_str), - dns_protocol_to_string(t->scope->protocol), - t->scope->link ? t->scope->link->name : "*", - af_to_name_short(t->scope->family), - strnull(pretty)); - - /* 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(t->key, key_str, sizeof key_str); - - log_struct(LOG_NOTICE, - LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_FAILURE), - 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", dns_server_string(t->server), - "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t->server->possible_feature_level), - NULL); - } - - /* 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("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s).", - t->id, - dns_resource_key_to_string(t->key, key_str, sizeof key_str), - dns_protocol_to_string(t->scope->protocol), - t->scope->link ? t->scope->link->name : "*", - af_to_name_short(t->scope->family), - st, - t->answer_source < 0 ? "none" : dns_transaction_source_to_string(t->answer_source), - t->answer_authenticated ? "authenticated" : "unsigned"); - - t->state = state; - - dns_transaction_close_connection(t); - 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); - - 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 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 = _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 != _DNS_SERVER_FEATURE_LEVEL_INVALID && - t->current_feature_level > t->clamp_feature_level) - t->current_feature_level = t->clamp_feature_level; - - 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); - - log_debug("Using DNS server %s for transaction %u.", dns_server_string(t->server), t->id); - - return 1; -} - -static void dns_transaction_retry(DnsTransaction *t, bool next_server) { - int r; - - assert(t); - - 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); - - r = dns_transaction_go(t); - if (r < 0) { - t->answer_errno = -r; - dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); - } -} - -static int dns_transaction_maybe_restart(DnsTransaction *t) { - int r; - - assert(t); - - /* 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 int on_stream_complete(DnsStream *s, int error) { - _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; - DnsTransaction *t; - - assert(s); - assert(s->transaction); - - /* Copy the data we care about out of the stream before we - * destroy it. */ - t = s->transaction; - p = dns_packet_ref(s->read_packet); - - dns_transaction_close_connection(t); - - if (ERRNO_IS_DISCONNECT(error)) { - usec_t usec; - - 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 0; - } - - log_debug_errno(error, "Connection failure for DNS TCP stream: %m"); - assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &usec) >= 0); - dns_server_packet_lost(t->server, IPPROTO_TCP, t->current_feature_level, usec - t->start_usec); - - dns_transaction_retry(t, true); - return 0; - } - if (error != 0) { - t->answer_errno = error; - dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); - return 0; - } - - 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); - 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 dns_transaction_open_tcp(DnsTransaction *t) { - _cleanup_close_ int fd = -1; - int r; - - assert(t); - - dns_transaction_close_connection(t); - - switch (t->scope->protocol) { - - case DNS_PROTOCOL_DNS: - r = dns_transaction_pick_server(t); - if (r < 0) - return r; - - if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(t->key->type)) - return -EOPNOTSUPP; - - r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level); - if (r < 0) - return r; - - fd = dns_scope_socket_tcp(t->scope, AF_UNSPEC, NULL, t->server, 53); - 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); - 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(t->key), &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); - } - - break; - - default: - return -EAFNOSUPPORT; - } - - if (fd < 0) - return fd; - - r = dns_stream_new(t->scope->manager, &t->stream, t->scope->protocol, fd); - if (r < 0) - return r; - fd = -1; - - r = dns_stream_write_packet(t->stream, t->sent); - if (r < 0) { - t->stream = dns_stream_unref(t->stream); - return r; - } - - t->stream->complete = on_stream_complete; - t->stream->transaction = t; - - /* 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 */ - t->stream->ifindex = dns_scope_ifindex(t->scope); - - 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) - return; - - /* We never cache if this packet is from the local host, under - * the assumption that a locally running DNS server would - * cache this anyway, and probably knows better when to flush - * the cache then we could. */ - if (!DNS_PACKET_SHALL_CACHE(t->received)) - return; - - dns_cache_put(&t->scope->cache, - t->key, - t->answer_rcode, - t->answer, - t->answer_authenticated, - t->answer_nsec_ttl, - 0, - t->received->family, - &t->received->sender); -} - -static bool dns_transaction_dnssec_is_live(DnsTransaction *t) { - DnsTransaction *dt; - Iterator i; - - assert(t); - - SET_FOREACH(dt, t->dnssec_transactions, i) - if (DNS_TRANSACTION_IS_LIVE(dt->state)) - return true; - - return false; -} - -static int dns_transaction_dnssec_ready(DnsTransaction *t) { - DnsTransaction *dt; - Iterator i; - - 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, i) { - - 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.", dns_rcode_to_string(dt->answer_rcode)); - goto fail; - } - - /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers - * erronously 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 - * validationr 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: - 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, refuse operation. */ - 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: - t->answer_errno = -r; - dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); -} - -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, t->key, flags); - if (r != 0) - return r; - - r = dns_answer_find_cname_or_dname(t->answer, t->key, 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) { - usec_t ts; - 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 on transaction %" PRIu16".", t->id); - - 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("Invalid DNS protocol."); - } - - if (t->received != p) { - dns_packet_unref(t->received); - 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; - } - } - - assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0); - - switch (t->scope->protocol) { - - case DNS_PROTOCOL_DNS: - assert(t->server); - - if (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_WORST) { - /* This was already at the lowest possible feature level? If so, we can't downgrade - * this transaction anymore, hence let's process the response, and accept the rcode. */ - log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p))); - break; - } - - /* Reduce this feature level by one and try again. */ - t->clamp_feature_level = t->current_feature_level - 1; - - log_debug("Server returned error %s, retrying transaction with reduced feature level %s.", - dns_rcode_to_string(DNS_PACKET_RCODE(p)), - dns_server_feature_level_to_string(t->clamp_feature_level)); - - dns_transaction_retry(t, false /* use the same server */); - return; - } else 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, ts - t->start_usec); - break; - - default: - assert_not_reached("Invalid DNS protocol."); - } - - 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; - } - - log_debug("Reply truncated, retrying via TCP."); - - /* Response was truncated, let's try again with good old TCP */ - r = dns_transaction_open_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 */ - dns_transaction_retry(t, true); - } - - return; - } - - /* After the superficial checks, actually parse the message. */ - r = dns_packet_extract(p); - if (r < 0) { - dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); - 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 != _DNS_SERVER_FEATURE_LEVEL_INVALID) - dns_server_packet_rcode_downgrade(t->server, t->clamp_feature_level); - - /* Report that the OPT RR was missing */ - if (!p->opt) - dns_server_packet_bad_opt(t->server, t->current_feature_level); - - /* Report that we successfully received a packet */ - dns_server_packet_received(t->server, p->ipproto, t->current_feature_level, ts - t->start_usec, p->size); - } - - /* 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; - - if (IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR)) { - - /* Only consider responses with equivalent query section to the request */ - r = dns_packet_is_reply_for(p, t->key); - 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 */ - dns_answer_unref(t->answer); - t->answer = dns_answer_ref(p->answer); - t->answer_rcode = DNS_PACKET_RCODE(p); - t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; - t->answer_authenticated = false; - - 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); - dns_transaction_stop_timeout(t); - return; - } - } - - dns_transaction_process_dnssec(t); - return; - -fail: - t->answer_errno = -r; - dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); -} - -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 = userdata; - int r; - - assert(t); - assert(t->scope); - - r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p); - if (ERRNO_IS_DISCONNECT(-r)) { - usec_t usec; - - /* UDP connection failure get reported via ICMP and then are possible 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_or_monotonic(), &usec) >= 0); - dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level, usec - t->start_usec); - - dns_transaction_retry(t, true); - return 0; - } - if (r < 0) { - dns_transaction_complete(t, DNS_TRANSACTION_ERRNO); - t->answer_errno = -r; - 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); - 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 (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_UDP) - return -EAGAIN; - - if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(t->key->type)) - return -EOPNOTSUPP; - - if (r > 0 || t->dns_udp_fd < 0) { /* Server changed, or no connection yet. */ - int fd; - - dns_transaction_close_connection(t); - - fd = dns_scope_socket_udp(t->scope, t->server, 53); - 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; - } - - r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level); - if (r < 0) - return r; - } else - dns_transaction_close_connection(t); - - r = dns_scope_emit_udp(t->scope, t->dns_udp_fd, 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 = userdata; - - assert(s); - assert(t); - - if (!t->initial_jitter_scheduled || t->initial_jitter_elapsed) { - /* 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, usec - t->start_usec); - break; - - case DNS_PROTOCOL_LLMNR: - case DNS_PROTOCOL_MDNS: - dns_scope_packet_lost(t->scope, usec - t->start_usec); - break; - - default: - assert_not_reached("Invalid DNS protocol."); - } - - if (t->initial_jitter_scheduled) - t->initial_jitter_elapsed = true; - } - - log_debug("Timeout reached on transaction %" PRIu16 ".", t->id); - - dns_transaction_retry(t, true); - return 0; -} - -static usec_t transaction_get_resend_timeout(DnsTransaction *t) { - assert(t); - assert(t->scope); - - switch (t->scope->protocol) { - - case DNS_PROTOCOL_DNS: - assert(t->server); - return t->server->resend_timeout; - - case DNS_PROTOCOL_MDNS: - 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("Invalid DNS protocol."); - } -} - -static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) { - int r; - - assert(t); - - dns_transaction_stop_timeout(t); - - r = dns_scope_network_good(t->scope); - if (r < 0) - return r; - if (r == 0) { - dns_transaction_complete(t, DNS_TRANSACTION_NETWORK_DOWN); - return 0; - } - - if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) { - dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED); - 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) { - r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, t->key, &t->answer); - if (r < 0) - return r; - if (r > 0) { - t->answer_rcode = DNS_RCODE_SUCCESS; - t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR; - t->answer_authenticated = true; - dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); - return 0; - } - - if (dns_name_is_root(dns_resource_key_name(t->key)) && - t->key->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; - t->answer_authenticated = false; - 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, but only if this transaction is not used - * for probing or verifying a zone item. */ - if (set_isempty(t->notify_zone_items)) { - - r = dns_zone_lookup(&t->scope->zone, t->key, 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; - t->answer_authenticated = true; - dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); - return 0; - } - } - - /* Check the cache, but only if this transaction is not used - * for probing or verifying a zone item. */ - if (set_isempty(t->notify_zone_items)) { - - /* 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. */ - 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, t->key, t->clamp_ttl, &t->answer_rcode, &t->answer, &t->answer_authenticated); - if (r < 0) - return r; - if (r > 0) { - 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; - } - } - - return 1; -} - -static int dns_transaction_make_packet_mdns(DnsTransaction *t) { - - _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; - bool add_known_answers = false; - DnsTransaction *other; - unsigned qdcount; - 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); - - r = dns_packet_new_query(&p, t->scope->protocol, 0, false); - if (r < 0) - return r; - - r = dns_packet_append_key(p, t->key, NULL); - if (r < 0) - return r; - - qdcount = 1; - - if (dns_key_is_shared(t->key)) - add_known_answers = true; - - /* - * 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 contraints allow them to be sent. - */ - - assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0); - - LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) { - - /* Skip ourselves */ - if (other == t) - continue; - - if (other->state != DNS_TRANSACTION_PENDING) - continue; - - if (other->next_attempt_after > ts) - continue; - - if (qdcount >= UINT16_MAX) - break; - - r = dns_packet_append_key(p, other->key, NULL); - - /* - * 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_transaction_prepare(other, ts); - if (r <= 0) - continue; - - ts += transaction_get_resend_timeout(other); - - r = sd_event_add_time( - other->scope->manager->event, - &other->timeout_event_source, - clock_boottime_or_monotonic(), - ts, 0, - on_transaction_timeout, other); - if (r < 0) - return r; - - (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout"); - - other->state = DNS_TRANSACTION_PENDING; - other->next_attempt_after = ts; - - qdcount++; - - if (dns_key_is_shared(other->key)) - add_known_answers = true; - } - - DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount); - - /* 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); - if (r < 0) - return r; - } - - t->sent = p; - p = NULL; - - 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; - - r = dns_packet_new_query(&p, t->scope->protocol, 0, t->scope->dnssec_mode != DNSSEC_NO); - if (r < 0) - return r; - - r = dns_packet_append_key(p, t->key, NULL); - if (r < 0) - return r; - - DNS_PACKET_HEADER(p)->qdcount = htobe16(1); - DNS_PACKET_HEADER(p)->id = t->id; - - t->sent = p; - p = NULL; - - 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. */ - - assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0); - - r = dns_transaction_prepare(t, ts); - if (r <= 0) - return r; - - log_debug("Transaction %" PRIu16 " for <%s> scope %s on %s/%s.", - t->id, - dns_resource_key_to_string(t->key, key_str, sizeof key_str), - dns_protocol_to_string(t->scope->protocol), - t->scope->link ? t->scope->link->name : "*", - af_to_name_short(t->scope->family)); - - if (!t->initial_jitter_scheduled && - (t->scope->protocol == DNS_PROTOCOL_LLMNR || - t->scope->protocol == DNS_PROTOCOL_MDNS)) { - usec_t jitter, accuracy; - - /* RFC 4795 Section 2.7 suggests all queries should be - * delayed by a random time from 0 to JITTER_INTERVAL. */ - - t->initial_jitter_scheduled = true; - - random_bytes(&jitter, sizeof(jitter)); - - switch (t->scope->protocol) { - - case DNS_PROTOCOL_LLMNR: - jitter %= LLMNR_JITTER_INTERVAL_USEC; - accuracy = LLMNR_JITTER_INTERVAL_USEC; - break; - - case DNS_PROTOCOL_MDNS: - jitter %= MDNS_JITTER_RANGE_USEC; - jitter += MDNS_JITTER_MIN_USEC; - accuracy = MDNS_JITTER_RANGE_USEC; - break; - default: - assert_not_reached("bad protocol"); - } - - r = sd_event_add_time( - t->scope->manager->event, - &t->timeout_event_source, - clock_boottime_or_monotonic(), - ts + jitter, accuracy, - on_transaction_timeout, t); - if (r < 0) - return r; - - (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout"); - - t->n_attempts = 0; - t->next_attempt_after = ts; - t->state = DNS_TRANSACTION_PENDING; - - log_debug("Delaying %s transaction for " USEC_FMT "us.", dns_protocol_to_string(t->scope->protocol), jitter); - return 0; - } - - /* 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(t->key), "in-addr.arpa") > 0 || - dns_name_endswith(dns_resource_key_name(t->key), "ip6.arpa") > 0)) { - - /* RFC 4795, Section 2.4. says reverse lookups shall - * always be made via TCP on LLMNR */ - r = dns_transaction_open_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."); - if (r == -EAGAIN) - log_debug("Sending query via TCP since server doesn't support UDP."); - if (r == -EMSGSIZE || r == -EAGAIN) - r = dns_transaction_open_tcp(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); - - return dns_transaction_go(t); - } - - ts += transaction_get_resend_timeout(t); - - r = sd_event_add_time( - t->scope->manager->event, - &t->timeout_event_source, - clock_boottime_or_monotonic(), - ts, 0, - on_transaction_timeout, t); - if (r < 0) - return r; - - (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout"); - - t->state = DNS_TRANSACTION_PENDING; - t->next_attempt_after = ts; - - return 1; -} - -static int dns_transaction_find_cyclic(DnsTransaction *t, DnsTransaction *aux) { - DnsTransaction *n; - Iterator i; - 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, i) { - 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) { - DnsTransaction *aux; - int r; - - assert(t); - assert(ret); - assert(key); - - aux = dns_scope_find_transaction(t->scope, key, true); - if (!aux) { - r = dns_transaction_new(&aux, t->scope, key); - 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]; - - log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16 " (%s) as dependency for %" PRIu16 " (%s).", - aux->id, - dns_resource_key_to_string(t->key, s, sizeof s), - t->id, - dns_resource_key_to_string(aux->key, saux, sizeof saux)); - - return -ELOOP; - } - } - - r = set_ensure_allocated(&t->dnssec_transactions, NULL); - if (r < 0) - goto gc; - - r = set_ensure_allocated(&aux->notify_transactions, NULL); - if (r < 0) - goto gc; - - r = set_ensure_allocated(&aux->notify_transactions_done, NULL); - if (r < 0) - goto gc; - - r = set_put(t->dnssec_transactions, aux); - if (r < 0) - goto gc; - - r = set_put(aux->notify_transactions, t); - if (r < 0) { - (void) set_remove(t->dnssec_transactions, aux); - goto gc; - } - - *ret = aux; - return 1; - -gc: - dns_transaction_gc(aux); - return r; -} - -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 set_contains(t->scope->link->dnssec_negative_trust_anchors, name); -} - -static int dns_transaction_has_unsigned_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(t->key)); - if (r < 0) - return r; - if (r > 0) - return false; - - /* The answer does not contain any RRs that match to the - * question. If so, let's see if there are any NSEC/NSEC3 RRs - * included. If not, the answer is unsigned. */ - - r = dns_answer_contains_nsec_or_nsec3(t->answer); - if (r < 0) - return r; - if (r > 0) - return false; - - return true; -} - -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(t->key, rr, NULL); - if (r != 0) - return r; - - return dns_resource_key_match_cname_or_dname(t->key, 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; - Iterator i; - - 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, i) - 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 (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 geting 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 additonal RRs - * point back to the original transaction, and - * we deadlock. */ - r = dns_name_endswith(dns_resource_key_name(t->key), 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(t->key), 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(t->key, rr, NULL); - 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_unsigned_negative_answer(t); - if (r < 0) - return r; - if (r > 0) { - const char *name; - uint16_t type = 0; - - name = dns_resource_key_name(t->key); - - /* 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 (t->key->type == DNS_TYPE_DS) { - r = dns_name_parent(&name); - if (r > 0) { - type = DNS_TYPE_SOA; - log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned empty DS response).", - t->id, dns_resource_key_name(t->key)); - } else - name = NULL; - - } else if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS)) { - - type = DNS_TYPE_DS; - log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned empty SOA/NS response).", - t->id, dns_resource_key_name(t->key)); - - } else { - type = DNS_TYPE_SOA; - log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned empty non-SOA/NS/DS response).", - t->id, dns_resource_key_name(t->key)); - } - - if (name) { - _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL; - - soa = dns_resource_key_new(t->key->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) { - DnsResourceRecord *rr; - int ifindex, 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_IFINDEX(rr, ifindex, t->answer) { - - r = dnssec_verify_dnskey_by_ds_search(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, rr, ifindex, DNS_ANSWER_AUTHENTICATED); - 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; - Iterator i; - - /* For SOA or NS RRs we look for a matching DS transaction */ - - SET_FOREACH(dt, t->dnssec_transactions, i) { - - if (dt->key->class != rr->key->class) - continue; - if (dt->key->type != DNS_TYPE_DS) - continue; - - r = dns_name_equal(dns_resource_key_name(dt->key), 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 (!dt->answer_authenticated) - return false; - - return dns_answer_match_key(dt->answer, dt->key, 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; - Iterator i; - - /* - * 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, i) { - - if (dt->key->class != rr->key->class) - continue; - if (dt->key->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. */ - log_debug("Transaction %" PRIu16 " claims CNAME/DNAME at root. Refusing.", t->id); - return -EBADMSG; - } - } - - r = dns_name_equal(dns_resource_key_name(dt->key), parent); - if (r < 0) - return r; - if (r == 0) - continue; - - return t->answer_authenticated; - } - - return true; - } - - default: { - DnsTransaction *dt; - Iterator i; - - /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */ - - SET_FOREACH(dt, t->dnssec_transactions, i) { - - if (dt->key->class != rr->key->class) - continue; - if (dt->key->type != DNS_TYPE_SOA) - continue; - - r = dns_name_equal(dns_resource_key_name(dt->key), 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 t->answer_authenticated; - } - - return true; - }} -} - -static int dns_transaction_in_private_tld(DnsTransaction *t, const DnsResourceKey *key) { - DnsTransaction *dt; - const char *tld; - Iterator i; - 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, i) { - - if (dt->key->class != key->class) - continue; - - r = dns_name_equal(dns_resource_key_name(dt->key), 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; - Iterator i; - 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(t->key->type)) - return -EINVAL; - - r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(t->key)); - if (r < 0) - return r; - if (r > 0) - return false; - - r = dns_transaction_in_private_tld(t, t->key); - 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(t->key, key_str, sizeof key_str)); - return false; - } - - name = dns_resource_key_name(t->key); - - if (t->key->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(t->key->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, i) { - - if (dt->key->class != t->key->class) - continue; - if (dt->key->type != type) - continue; - - r = dns_name_equal(dns_resource_key_name(dt->key), name); - if (r < 0) - return r; - if (r == 0) - continue; - - return dt->answer_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; - Iterator i; - - r = dnssec_key_match_rrsig(rr->key, rrsig); - if (r < 0) - return r; - if (r == 0) - continue; - - SET_FOREACH(dt, t->dnssec_transactions, i) { - - if (dt->key->class != rr->key->class) - continue; - - if (dt->key->type == DNS_TYPE_DNSKEY) { - - r = dns_name_equal(dns_resource_key_name(dt->key), 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 (dt->answer_authenticated) - return true; - - found = true; - - } else if (dt->key->type == DNS_TYPE_DS) { - - r = dns_name_equal(dns_resource_key_name(dt->key), 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 (!dt->answer_authenticated) - return false; - - return dns_answer_match_key(dt->answer, dt->key, 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; - Iterator i; - 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, i) { - - if (DNS_TRANSACTION_IS_LIVE(dt->state)) - continue; - - if (!dt->answer_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) { - 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) { - - 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); - 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); - 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; - - /* 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); - 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); - 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); - 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); - 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, - DNSSEC_UNSUPPORTED_ALGORITHM)) { - - 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); - 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 (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; - t->answer_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(t->key, 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_unref(t->answer); - t->answer = validated; - validated = NULL; - - /* 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; - t->answer_authenticated = true; - } else { - /* The answer is not fully authenticated. */ - t->answer_dnssec_result = DNSSEC_UNSIGNED; - t->answer_authenticated = false; - } - - } else if (r == 0) { - DnssecNsecResult nr; - bool authenticated = false; - - /* Bummer! Let's check NSEC/NSEC3 */ - r = dnssec_nsec_test(t->answer, t->key, &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; - t->answer_authenticated = authenticated; - - manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, t->key); - 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; - t->answer_authenticated = authenticated; - - manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, t->key); - 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; - t->answer_authenticated = false; - - manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, t->key); - 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, t->key); - } else { - t->answer_dnssec_result = DNSSEC_UNSIGNED; - t->answer_authenticated = false; - manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, t->key); - } - - 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, t->key); - 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, t->key); - break; - - default: - assert_not_reached("Unexpected NSEC result."); - } - } - - 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", -}; -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); |