diff options
Diffstat (limited to 'src/resolve/resolved-dns-transaction.c')
| -rw-r--r-- | src/resolve/resolved-dns-transaction.c | 2296 |
1 files changed, 2133 insertions, 163 deletions
diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c index 90f07e6c4b..5640cd1d33 100644 --- a/src/resolve/resolved-dns-transaction.c +++ b/src/resolve/resolved-dns-transaction.c @@ -19,6 +19,8 @@ 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" @@ -29,25 +31,62 @@ #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; +} + +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); + dns_transaction_gc(z); + } +} + +static void dns_transaction_close_connection(DnsTransaction *t) { + assert(t); + + t->stream = dns_stream_free(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; - sd_event_source_unref(t->timeout_event_source); - - dns_packet_unref(t->sent); - dns_packet_unref(t->received); + log_debug("Freeing transaction %" PRIu16 ".", t->id); - dns_answer_unref(t->answer); + dns_transaction_close_connection(t); + dns_transaction_stop_timeout(t); - sd_event_source_unref(t->dns_udp_event_source); - safe_close(t->dns_udp_fd); + dns_packet_unref(t->sent); + dns_transaction_reset_answer(t); dns_server_unref(t->server); - dns_stream_free(t->stream); if (t->scope) { hashmap_remove_value(t->scope->transactions_by_key, t->key, t); @@ -57,16 +96,24 @@ DnsTransaction* dns_transaction_free(DnsTransaction *t) { hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id)); } - dns_resource_key_unref(t->key); - - while ((c = set_steal_first(t->query_candidates))) + while ((c = set_steal_first(t->notify_query_candidates))) set_remove(c->transactions, t); + set_free(t->notify_query_candidates); - set_free(t->query_candidates); - - while ((i = set_steal_first(t->zone_items))) + while ((i = set_steal_first(t->notify_zone_items))) i->probe_transaction = NULL; - set_free(t->zone_items); + set_free(t->notify_zone_items); + + while ((z = set_steal_first(t->notify_transactions))) + set_remove(z->dnssec_transactions, t); + set_free(t->notify_transactions); + + dns_transaction_flush_dnssec_transactions(t); + set_free(t->dnssec_transactions); + + dns_answer_unref(t->validated_keys); + dns_resource_key_unref(t->key); + free(t->key_string); free(t); return NULL; @@ -74,14 +121,36 @@ DnsTransaction* dns_transaction_free(DnsTransaction *t) { DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free); -void dns_transaction_gc(DnsTransaction *t) { +bool dns_transaction_gc(DnsTransaction *t) { assert(t); if (t->block_gc > 0) - return; + return true; - if (set_isempty(t->query_candidates) && set_isempty(t->zone_items)) + if (set_isempty(t->notify_query_candidates) && + set_isempty(t->notify_zone_items) && + set_isempty(t->notify_transactions)) { 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) { @@ -92,6 +161,19 @@ int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) 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; @@ -106,13 +188,12 @@ int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) 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; - /* Find a fresh, unused transaction id */ - do - random_bytes(&t->id, sizeof(t->id)); - while (t->id == 0 || - hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(t->id))); + t->id = pick_new_id(s->manager); r = hashmap_put(s->manager->dns_transactions, UINT_TO_PTR(t->id), t); if (r < 0) { @@ -129,6 +210,8 @@ int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) LIST_PREPEND(transactions_by_scope, s->transactions, t); t->scope = s; + s->manager->n_transactions_total ++; + if (ret) *ret = t; @@ -137,14 +220,20 @@ int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) return 0; } -static void dns_transaction_stop(DnsTransaction *t) { +static void dns_transaction_shuffle_id(DnsTransaction *t) { + uint16_t new_id; assert(t); - t->timeout_event_source = sd_event_source_unref(t->timeout_event_source); - t->stream = dns_stream_free(t->stream); + /* 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; - /* Note that we do not drop the UDP socket here, as we want to - * reuse it to repeat the interaction. */ + /* 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) { @@ -159,7 +248,9 @@ static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) { in_addr_to_string(p->family, &p->sender, &pretty); - log_debug("Transaction on scope %s on %s/%s got tentative packet from %s", + log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s got tentative packet from %s.", + t->id, + dns_transaction_key_string(t), dns_protocol_to_string(t->scope->protocol), t->scope->link ? t->scope->link->name : "*", t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family), @@ -175,7 +266,7 @@ static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) { log_debug("We have the lexicographically larger IP address and thus lost in the conflict."); t->block_gc++; - while ((z = set_first(t->zone_items))) { + 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); @@ -192,38 +283,138 @@ static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) { void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state) { DnsQueryCandidate *c; DnsZoneItem *z; + DnsTransaction *d; Iterator i; assert(t); - assert(!IN_SET(state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING)); + assert(!DNS_TRANSACTION_IS_LIVE(state)); + + if (state == DNS_TRANSACTION_DNSSEC_FAILED) + log_struct(LOG_NOTICE, + LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_FAILURE), + LOG_MESSAGE("DNSSEC validation failed for question %s: %s", dns_transaction_key_string(t), dnssec_result_to_string(t->answer_dnssec_result)), + "DNS_TRANSACTION=%" PRIu16, t->id, + "DNS_QUESTION=%s", dns_transaction_key_string(t), + "DNSSEC_RESULT=%s", dnssec_result_to_string(t->answer_dnssec_result), + NULL); /* 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("Transaction on scope %s on %s/%s now complete with <%s> from %s", + log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s).", + t->id, + dns_transaction_key_string(t), dns_protocol_to_string(t->scope->protocol), t->scope->link ? t->scope->link->name : "*", t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family), dns_transaction_state_to_string(state), - t->answer_source < 0 ? "none" : dns_transaction_source_to_string(t->answer_source)); + t->answer_source < 0 ? "none" : dns_transaction_source_to_string(t->answer_source), + t->answer_authenticated ? "authenticated" : "unsigned"); t->state = state; - dns_transaction_stop(t); + 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(c, t->query_candidates, i) - dns_query_candidate_ready(c); - SET_FOREACH(z, t->zone_items, i) - dns_zone_item_ready(z); - t->block_gc--; + SET_FOREACH(c, t->notify_query_candidates, i) + dns_query_candidate_notify(c); + SET_FOREACH(z, t->notify_zone_items, i) + dns_zone_item_notify(z); + + if (!set_isempty(t->notify_transactions)) { + DnsTransaction **nt; + unsigned j, n = 0; + + /* We need to be careful when notifying other + * transactions, as that might destroy other + * transactions in our list. Hence, in order to be + * able to safely iterate through the list of + * transactions, take a GC lock on all of them + * first. Then, in a second loop, notify them, but + * first unlock that specific transaction. */ + + nt = newa(DnsTransaction*, set_size(t->notify_transactions)); + SET_FOREACH(d, t->notify_transactions, i) { + nt[n++] = d; + d->block_gc++; + } + + assert(n == set_size(t->notify_transactions)); + + for (j = 0; j < n; j++) { + if (set_contains(t->notify_transactions, nt[j])) + dns_transaction_notify(nt[j], t); + + nt[j]->block_gc--; + dns_transaction_gc(nt[j]); + } + } + + 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); + + server = dns_scope_get_dns_server(t->scope); + if (!server) + return -ESRCH; + + t->current_feature_level = dns_server_possible_feature_level(server); + + if (server == t->server) + return 0; + + dns_server_unref(t->server); + t->server = dns_server_ref(server); + + return 1; +} + +static void dns_transaction_retry(DnsTransaction *t) { + int r; + + assert(t); + + log_debug("Retrying transaction %" PRIu16 ".", t->id); + + /* Before we try again, switch to a new server. */ + dns_scope_next_dns_server(t->scope); + + r = dns_transaction_go(t); + if (r < 0) + dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); +} + +static int dns_transaction_maybe_restart(DnsTransaction *t) { + assert(t); + + 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); + return dns_transaction_go(t); +} + static int on_stream_complete(DnsStream *s, int error) { _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; DnsTransaction *t; @@ -238,6 +429,16 @@ static int on_stream_complete(DnsStream *s, int error) { t->stream = dns_stream_free(t->stream); + if (ERRNO_IS_DISCONNECT(error)) { + usec_t usec; + + 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); + return 0; + } if (error != 0) { dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); return 0; @@ -255,32 +456,46 @@ static int on_stream_complete(DnsStream *s, int error) { dns_transaction_process_reply(t, p); t->block_gc--; - /* If the response wasn't useful, then complete the transition now */ + /* 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) { - DnsServer *server = NULL; _cleanup_close_ int fd = -1; int r; assert(t); - if (t->stream) - return 0; + dns_transaction_close_connection(t); switch (t->scope->protocol) { + case DNS_PROTOCOL_DNS: - fd = dns_scope_tcp_socket(t->scope, AF_UNSPEC, NULL, 53, &server); + 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_tcp_socket(t->scope, t->received->family, &t->received->sender, t->received->sender_port, NULL); + 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; @@ -297,7 +512,7 @@ static int dns_transaction_open_tcp(DnsTransaction *t) { if (family != t->scope->family) return -ESRCH; - fd = dns_scope_tcp_socket(t->scope, family, &address, LLMNR_PORT, NULL); + fd = dns_scope_socket_tcp(t->scope, family, &address, NULL, LLMNR_PORT); } break; @@ -312,7 +527,6 @@ static int dns_transaction_open_tcp(DnsTransaction *t) { 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); @@ -321,11 +535,6 @@ static int dns_transaction_open_tcp(DnsTransaction *t) { return r; } - dns_server_unref(t->server); - t->server = dns_server_ref(server); - t->received = dns_packet_unref(t->received); - t->answer = dns_answer_unref(t->answer); - t->answer_rcode = 0; t->stream->complete = on_stream_complete; t->stream->transaction = t; @@ -335,17 +544,165 @@ static int dns_transaction_open_tcp(DnsTransaction *t) { if (t->scope->link) t->stream->ifindex = t->scope->link->ifindex; + dns_transaction_reset_answer(t); + + t->tried_stream = true; + return 0; } -static void dns_transaction_next_dns_server(DnsTransaction *t) { +static void dns_transaction_cache_answer(DnsTransaction *t) { assert(t); - t->server = dns_server_unref(t->server); - t->dns_udp_event_source = sd_event_source_unref(t->dns_udp_event_source); - t->dns_udp_fd = safe_close(t->dns_udp_fd); + /* 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; - dns_scope_next_dns_server(t->scope); + /* 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 (dt->answer_rcode != DNS_RCODE_NXDOMAIN) { + log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt->answer_rcode)); + goto fail; + } + + /* Fall-through: NXDOMAIN is good enough for us. This is because some DNS servers erronously + * return NXDOMAIN for empty non-terminals (Akamai...), 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) { + dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); + return; + } + 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) { + dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); + return; + } + 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 < 0) { + dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); + return; + } + + 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; + } + + 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); } void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) { @@ -354,15 +711,20 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) { assert(t); assert(p); - assert(t->state == DNS_TRANSACTION_PENDING); 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: assert(t->scope->link); @@ -398,6 +760,11 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) { 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: @@ -428,34 +795,30 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) { 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 */ + /* Request failed, immediately try again with reduced features */ log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p))); - dns_server_packet_failed(t->server, t->current_features); - - r = dns_transaction_go(t); - if (r < 0) { - dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); - return; - } - + dns_server_packet_failed(t->server, t->current_feature_level); + dns_transaction_retry(t); return; - } else - dns_server_packet_received(t->server, t->current_features, ts - t->start_usec, p->size); + } 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: - break; + assert_not_reached("Invalid DNS protocol."); } if (DNS_PACKET_TC(p)) { @@ -466,6 +829,8 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) { 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) { @@ -473,37 +838,59 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) { 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 and mDNS, if we cannot connect to the host, + /* On LLMNR, if we cannot connect to the host, * we immediately give up */ - if (t->scope->protocol == DNS_PROTOCOL_LLMNR) { + if (t->scope->protocol != DNS_PROTOCOL_DNS) { dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); return; } /* On DNS, couldn't send? Try immediately again, with a new server */ - dns_transaction_next_dns_server(t); - - r = dns_transaction_go(t); - if (r < 0) { - dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); - return; - } - - return; + dns_transaction_retry(t); } + + return; } - /* Parse and update the cache */ + /* 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->scope->protocol == DNS_PROTOCOL_DNS) { + /* Report that the OPT RR was missing */ + if (t->server) { + if (!p->opt) + dns_server_packet_bad_opt(t->server, t->current_feature_level); + + 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) { + dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); + return; + } + 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 */ - if (p->question->n_keys != 1 || dns_resource_key_equal(p->question->keys[0], t->key) <= 0) { + r = dns_packet_is_reply_for(p, t->key); + if (r < 0) { + dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); + return; + } + if (r == 0) { dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY); return; } @@ -512,25 +899,39 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) { dns_answer_unref(t->answer); t->answer = dns_answer_ref(p->answer); t->answer_rcode = DNS_PACKET_RCODE(p); - t->answer_authenticated = t->scope->dnssec_mode == DNSSEC_TRUST && DNS_PACKET_AD(p); - - /* According to RFC 4795, section 2.9. only the RRs from the answer section shall be cached */ - if (DNS_PACKET_SHALL_CACHE(p)) - dns_cache_put(&t->scope->cache, - t->key, - DNS_PACKET_RCODE(p), - p->answer, - DNS_PACKET_ANCOUNT(p), - t->answer_authenticated, - 0, - p->family, - &p->sender); - } - - if (DNS_PACKET_RCODE(p) == DNS_RCODE_SUCCESS) - dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); - else - dns_transaction_complete(t, DNS_TRANSACTION_FAILURE); + t->answer_dnssec_result = _DNSSEC_RESULT_INVALID; + t->answer_authenticated = false; + + /* 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) { + dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); + return; + } + 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); } static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { @@ -542,53 +943,96 @@ static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *use assert(t->scope); r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p); - if (r <= 0) - return r; + if (ERRNO_IS_DISCONNECT(-r)) { + usec_t usec; - if (dns_packet_validate_reply(p) > 0 && - DNS_PACKET_ID(p) == t->id) - dns_transaction_process_reply(t, p); - else - log_debug("Invalid DNS packet."); + /* 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); + return 0; + } + if (r < 0) { + dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); + 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(DnsTransaction *t) { +static int dns_transaction_emit_udp(DnsTransaction *t) { int r; assert(t); - if (t->scope->protocol == DNS_PROTOCOL_DNS && !t->server) { - DnsServer *server = NULL; - _cleanup_close_ int fd = -1; - - fd = dns_scope_udp_dns_socket(t->scope, &server); - if (fd < 0) - return fd; + if (t->scope->protocol == DNS_PROTOCOL_DNS) { - r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t); + r = dns_transaction_pick_server(t); if (r < 0) return r; - t->dns_udp_fd = fd; - fd = -1; - t->server = dns_server_ref(server); - } + 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); - r = dns_scope_emit(t->scope, t->dns_udp_fd, t->server, t->sent); + 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; - if (t->server) - t->current_features = t->server->possible_features; + dns_transaction_reset_answer(t); return 0; } static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) { DnsTransaction *t = userdata; - int r; assert(s); assert(t); @@ -596,17 +1040,17 @@ static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdat 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->current_features, usec - t->start_usec); - + 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."); } @@ -615,13 +1059,9 @@ static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdat t->initial_jitter_elapsed = true; } - /* ...and try again with a new server */ - dns_transaction_next_dns_server(t); - - r = dns_transaction_go(t); - if (r < 0) - dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); + log_debug("Timeout reached on transaction %" PRIu16 ".", t->id); + dns_transaction_retry(t); return 0; } @@ -630,36 +1070,36 @@ static usec_t transaction_get_resend_timeout(DnsTransaction *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_next_attempt(DnsTransaction *t, usec_t ts) { - bool had_stream; +static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) { int r; assert(t); - had_stream = !!t->stream; - - dns_transaction_stop(t); + dns_transaction_stop_timeout(t); 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 && had_stream) { + 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); @@ -668,14 +1108,13 @@ static int dns_transaction_prepare_next_attempt(DnsTransaction *t, usec_t ts) { t->n_attempts++; t->start_usec = ts; - t->received = dns_packet_unref(t->received); - t->answer = dns_answer_unref(t->answer); - t->answer_rcode = 0; - t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID; + + 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(&t->scope->manager->trust_anchor, t->key, &t->answer); + r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, t->key, &t->answer); if (r < 0) return r; if (r > 0) { @@ -685,11 +1124,46 @@ static int dns_transaction_prepare_next_attempt(DnsTransaction *t, usec_t ts) { 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 it and trust + * it). */ + 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->zone_items)) { + if (set_isempty(t->notify_zone_items)) { r = dns_zone_lookup(&t->scope->zone, t->key, &t->answer, NULL, NULL); if (r < 0) @@ -705,7 +1179,7 @@ static int dns_transaction_prepare_next_attempt(DnsTransaction *t, usec_t ts) { /* Check the cache, but only if this transaction is not used * for probing or verifying a zone item. */ - if (set_isempty(t->zone_items)) { + 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 @@ -723,7 +1197,7 @@ static int dns_transaction_prepare_next_attempt(DnsTransaction *t, usec_t ts) { if (t->answer_rcode == DNS_RCODE_SUCCESS) dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS); else - dns_transaction_complete(t, DNS_TRANSACTION_FAILURE); + dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE); return 0; } } @@ -743,7 +1217,7 @@ static int dns_transaction_make_packet_mdns(DnsTransaction *t) { assert(t); assert(t->scope->protocol == DNS_PROTOCOL_MDNS); - /* Discard any previously prepared packet, so we can start over and coaleasce again */ + /* 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); @@ -794,7 +1268,7 @@ static int dns_transaction_make_packet_mdns(DnsTransaction *t) { if (r < 0) return r; - r = dns_transaction_prepare_next_attempt(other, ts); + r = dns_transaction_prepare(other, ts); if (r <= 0) continue; @@ -809,6 +1283,8 @@ static int dns_transaction_make_packet_mdns(DnsTransaction *t) { 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; @@ -819,7 +1295,6 @@ static int dns_transaction_make_packet_mdns(DnsTransaction *t) { } DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount); - DNS_PACKET_HEADER(p)->id = t->id; /* Append known answer section if we're asking for any shared record */ if (add_known_answers) { @@ -846,7 +1321,7 @@ static int dns_transaction_make_packet(DnsTransaction *t) { if (t->sent) return 0; - r = dns_packet_new_query(&p, t->scope->protocol, 0, t->scope->dnssec_mode == DNSSEC_YES); + r = dns_packet_new_query(&p, t->scope->protocol, 0, t->scope->dnssec_mode != DNSSEC_NO); if (r < 0) return r; @@ -876,11 +1351,14 @@ int dns_transaction_go(DnsTransaction *t) { assert(t); assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0); - r = dns_transaction_prepare_next_attempt(t, ts); + + r = dns_transaction_prepare(t, ts); if (r <= 0) return r; - log_debug("Excercising transaction on scope %s on %s/%s", + log_debug("Excercising transaction %" PRIu16 " for <%s> on scope %s on %s/%s.", + t->id, + dns_transaction_key_string(t), dns_protocol_to_string(t->scope->protocol), t->scope->link ? t->scope->link->name : "*", t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family)); @@ -898,10 +1376,12 @@ int dns_transaction_go(DnsTransaction *t) { 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; @@ -920,6 +1400,8 @@ int dns_transaction_go(DnsTransaction *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; @@ -950,7 +1432,11 @@ int dns_transaction_go(DnsTransaction *t) { } else { /* Try via UDP, and if that fails due to large size or lack of * support try via TCP */ - r = dns_transaction_emit(t); + 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); } @@ -959,14 +1445,20 @@ int dns_transaction_go(DnsTransaction *t) { /* No servers to send this to? */ dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS); return 0; - } else if (r < 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 (r < 0) { if (t->scope->protocol != DNS_PROTOCOL_DNS) { dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES); return 0; } /* Couldn't send? Try immediately again, with a new server */ - dns_transaction_next_dns_server(t); + dns_scope_next_dns_server(t->scope); return dns_transaction_go(t); } @@ -982,16 +1474,1491 @@ int dns_transaction_go(DnsTransaction *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) { + log_debug("Detected potential cyclic dependency, refusing to add transaction %" PRIu16 " (%s) as dependency for %" PRIu16 " (%s).", + aux->id, + strna(dns_transaction_key_string(aux)), + t->id, + strna(dns_transaction_key_string(t))); + 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_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_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_negative_trust_anchor_lookup(DnsTransaction *t, const char *name) { + int r; + + assert(t); + + /* Check whether the specified name is in the 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, or is any kind of NSEC/NSEC3 RR */ + + r = dns_resource_key_match_rr(t->key, rr, NULL); + if (r != 0) + return r; + + r = dns_resource_key_match_cname_or_dname(t->key, rr->key, NULL); + if (r != 0) + return r; + + if (rr->key->type == DNS_TYPE_NSEC3) { + const char *p; + + p = DNS_RESOURCE_KEY_NAME(rr->key); + r = dns_name_parent(&p); + if (r < 0) + return r; + if (r > 0) { + r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(t->key), p); + if (r < 0) + return r; + if (r > 0) + return true; + } + } + + return rr->key->type == DNS_TYPE_NSEC; +} + +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; + + if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_DO) + return false; + + 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/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; + + name = DNS_RESOURCE_KEY_NAME(t->key); + + /* If this was a SOA or NS request, then this + * indicates that we are not at a zone apex, hence ask + * the parent name instead. If this was a DS request, + * then it's signed when the parent zone is signed, + * hence ask the parent in that case, too. */ + + if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS, DNS_TYPE_DS)) { + r = dns_name_parent(&name); + if (r < 0) + return r; + if (r > 0) + log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned empty SOA/NS/DS response).", t->id, DNS_RESOURCE_KEY_NAME(t->key)); + else + name = NULL; + } else + 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, DNS_TYPE_SOA, 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) { + DnsTransaction *dt; + const char *name; + 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_transaction_key_string(t)); + return false; + } + + name = DNS_RESOURCE_KEY_NAME(t->key); + + if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS, DNS_TYPE_DS)) { + + /* We got a negative reply for this SOA/NS lookup? If + * so, then we are not at a zone apex, and thus should + * look at the result of the parent SOA lookup. + * + * We got a negative reply for this DS lookup? DS RRs + * are signed when their parent zone is signed, hence + * also check the parent SOA in this case. */ + + r = dns_name_parent(&name); + if (r < 0) + return r; + if (r == 0) + return true; + } + + /* 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 != DNS_TYPE_SOA) + 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; +} + +int dns_transaction_validate_dnssec(DnsTransaction *t) { + _cleanup_(dns_answer_unrefp) DnsAnswer *validated = NULL; + enum { + PHASE_DNSKEY, /* Phase #1, only validate DNSKEYs */ + PHASE_NSEC, /* Phase #2, only validate NSEC+NSEC3 */ + PHASE_ALL, /* Phase #3, validate everything else */ + } phase; + DnsResourceRecord *rr; + DnsAnswerFlags flags; + int r; + + 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, server lacks DNSSEC support."); + return 0; + } + + log_debug("Validating response from transaction %" PRIu16 " (%s).", t->id, dns_transaction_key_string(t)); + + /* 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 = PHASE_DNSKEY; + for (;;) { + bool changed = false, have_nsec = false; + + 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 == 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 == PHASE_DNSKEY) + continue; + + break; + + default: + /* We validate all other RRs only in the ALL phases */ + if (phase != PHASE_ALL) + continue; + + break; + } + + 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; + + t->scope->manager->n_dnssec_secure++; + + /* Exit the loop, we dropped something from the answer, start from the beginning */ + changed = true; + break; + } + + /* 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 != 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; + + if (authenticated) + t->scope->manager->n_dnssec_secure++; + else + t->scope->manager->n_dnssec_insecure++; + + /* Exit the loop, we dropped something from the answer, start from the beginning */ + changed = true; + break; + } + } + + 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; + + t->scope->manager->n_dnssec_insecure++; + changed = true; + break; + } + + 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; + + t->scope->manager->n_dnssec_insecure++; + changed = true; + break; + } + + /* 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) { + _cleanup_free_ char *s = NULL; + + /* 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. */ + + (void) dns_resource_key_to_string(rr->key, &s); + log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.", strna(s ? strstrip(s) : NULL)); + + r = dns_answer_move_by_key(&validated, &t->answer, rr->key, 0); + if (r < 0) + return r; + + t->scope->manager->n_dnssec_insecure++; + changed = true; + break; + } + } + + 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; + + t->scope->manager->n_dnssec_insecure++; + changed = true; + break; + } + } + + if (IN_SET(result, + DNSSEC_INVALID, + DNSSEC_SIGNATURE_EXPIRED, + DNSSEC_NO_SIGNATURE)) + t->scope->manager->n_dnssec_bogus++; + else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */ + t->scope->manager->n_dnssec_indeterminate++; + + 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) { + /* 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; + + /* Exit the loop, we dropped something from the answer, start from the beginning */ + changed = true; + break; + } + + /* Restart the inner loop as long as we managed to achieve something */ + if (changed) + continue; + + if (phase == PHASE_DNSKEY && have_nsec) { + /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */ + phase = PHASE_NSEC; + continue; + } + + if (phase != 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 = 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, dns_transaction_key_string(t)); + t->answer_dnssec_result = DNSSEC_VALIDATED; + t->answer_rcode = DNS_RCODE_NXDOMAIN; + t->answer_authenticated = authenticated; + 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, dns_transaction_key_string(t)); + t->answer_dnssec_result = DNSSEC_VALIDATED; + t->answer_rcode = DNS_RCODE_SUCCESS; + t->answer_authenticated = authenticated; + 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, dns_transaction_key_string(t)); + t->answer_dnssec_result = DNSSEC_UNSIGNED; + t->answer_authenticated = false; + 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; + else { + t->answer_dnssec_result = DNSSEC_UNSIGNED; + t->answer_authenticated = false; + } + + break; + + case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM: + /* We don't know the NSEC3 algorithm used? */ + t->answer_dnssec_result = DNSSEC_UNSUPPORTED_ALGORITHM; + 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; + break; + + default: + assert_not_reached("Unexpected NSEC result."); + } + } + + return 1; +} + +const char *dns_transaction_key_string(DnsTransaction *t) { + assert(t); + + if (!t->key_string) { + if (dns_resource_key_to_string(t->key, &t->key_string) < 0) + return "n/a"; + } + + return strstrip(t->key_string); +} + static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] = { [DNS_TRANSACTION_NULL] = "null", [DNS_TRANSACTION_PENDING] = "pending", - [DNS_TRANSACTION_FAILURE] = "failure", + [DNS_TRANSACTION_VALIDATING] = "validating", + [DNS_TRANSACTION_RCODE_FAILURE] = "rcode-failure", [DNS_TRANSACTION_SUCCESS] = "success", [DNS_TRANSACTION_NO_SERVERS] = "no-servers", [DNS_TRANSACTION_TIMEOUT] = "timeout", @@ -999,6 +2966,9 @@ static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] [DNS_TRANSACTION_INVALID_REPLY] = "invalid-reply", [DNS_TRANSACTION_RESOURCES] = "resources", [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", }; DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state, DnsTransactionState); |