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-rw-r--r--src/resolve/resolved-dns-server.c18
-rw-r--r--src/resolve/resolved-dns-server.h2
-rw-r--r--src/resolve/resolved-dns-transaction.c60
3 files changed, 68 insertions, 12 deletions
diff --git a/src/resolve/resolved-dns-server.c b/src/resolve/resolved-dns-server.c
index dcfef66d4c..2a0301aa49 100644
--- a/src/resolve/resolved-dns-server.c
+++ b/src/resolve/resolved-dns-server.c
@@ -457,6 +457,24 @@ const char *dns_server_string(DnsServer *server) {
return strna(server->server_string);
}
+bool dns_server_dnssec_supported(DnsServer *server) {
+ assert(server);
+
+ /* Returns whether the server supports DNSSEC according to what we know about it */
+
+ if (server->possible_feature_level < DNS_SERVER_FEATURE_LEVEL_DO)
+ return false;
+
+ if (server->rrsig_missing)
+ return false;
+
+ /* DNSSEC servers need to support TCP properly (see RFC5966), if they don't, we assume DNSSEC is borked too */
+ if (server->n_failed_tcp >= DNS_SERVER_FEATURE_RETRY_ATTEMPTS)
+ return false;
+
+ return true;
+}
+
static void dns_server_hash_func(const void *p, struct siphash *state) {
const DnsServer *s = p;
diff --git a/src/resolve/resolved-dns-server.h b/src/resolve/resolved-dns-server.h
index faa22babb5..323f702903 100644
--- a/src/resolve/resolved-dns-server.h
+++ b/src/resolve/resolved-dns-server.h
@@ -116,6 +116,8 @@ int dns_server_adjust_opt(DnsServer *server, DnsPacket *packet, DnsServerFeature
const char *dns_server_string(DnsServer *server);
+bool dns_server_dnssec_supported(DnsServer *server);
+
DnsServer *dns_server_find(DnsServer *first, int family, const union in_addr_union *in_addr);
void dns_server_unlink_all(DnsServer *first);
diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c
index 1450acb260..aa1970bc34 100644
--- a/src/resolve/resolved-dns-transaction.c
+++ b/src/resolve/resolved-dns-transaction.c
@@ -368,7 +368,7 @@ static int on_stream_complete(DnsStream *s, int error) {
if (ERRNO_IS_DISCONNECT(error)) {
usec_t usec;
- log_debug_errno(error, "Connection failure for DNS TCP stream, treating as lost packet: %m");
+ 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_features, usec - t->start_usec);
@@ -418,7 +418,7 @@ static int dns_transaction_open_tcp(DnsTransaction *t) {
if (r < 0)
return r;
- if (t->current_features < DNS_SERVER_FEATURE_LEVEL_DO && dns_type_is_dnssec(t->key->type))
+ 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_features);
@@ -797,7 +797,7 @@ static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *use
/* 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, treating as lost packet: %m");
+ 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_features, usec - t->start_usec);
@@ -842,7 +842,7 @@ static int dns_transaction_emit_udp(DnsTransaction *t) {
if (t->current_features < DNS_SERVER_FEATURE_LEVEL_UDP)
return -EAGAIN;
- if (t->current_features < DNS_SERVER_FEATURE_LEVEL_DO && dns_type_is_dnssec(t->key->type))
+ 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. */
@@ -1555,6 +1555,44 @@ static int dns_transaction_is_primary_response(DnsTransaction *t, DnsResourceRec
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_features < 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;
@@ -1578,11 +1616,10 @@ int dns_transaction_request_dnssec_keys(DnsTransaction *t) {
if (t->scope->dnssec_mode == DNSSEC_NO)
return 0;
-
- if (t->current_features < DNS_SERVER_FEATURE_LEVEL_DO)
- return 0; /* Server doesn't do DNSSEC, there's no point in requesting any RRs then. */
- if (t->server && t->server->rrsig_missing)
- return 0; /* Server handles DNSSEC requests, but isn't augmenting responses with RRSIGs. No point in trying DNSSEC then. */
+ 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) {
@@ -2373,11 +2410,10 @@ int dns_transaction_validate_dnssec(DnsTransaction *t) {
if (t->answer_source != DNS_TRANSACTION_NETWORK)
return 0;
- if (t->current_features < DNS_SERVER_FEATURE_LEVEL_DO ||
- (t->server && t->server->rrsig_missing)) {
+ 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("Cannot validate reponse, server lacks DNSSEC support.");
+ log_debug("Cannot validate response, server lacks DNSSEC support.");
return 0;
}