Merge pull request #2092 from poettering/dnssec2

Second DNSSEC patch set

28 files changed, 422 insertions, 108 deletions

diff --git a/Makefile.am b/Makefile.am
index edae4a309b..db916f72c5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -5184,6 +5184,8 @@ systemd_resolved_SOURCES = \
 	src/resolve/resolved-dns-stream.c \
 	src/resolve/resolved-dns-dnssec.h \
 	src/resolve/resolved-dns-dnssec.c \
+	src/resolve/resolved-dns-trust-anchor.h \
+	src/resolve/resolved-dns-trust-anchor.c \
 	src/resolve/dns-type.c \
 	src/resolve/dns-type.h
 
diff --git a/src/resolve-host/resolve-host.c b/src/resolve-host/resolve-host.c
index 36dfc70e00..0f154d9798 100644
--- a/src/resolve-host/resolve-host.c
+++ b/src/resolve-host/resolve-host.c
@@ -67,6 +67,8 @@ static void print_source(uint64_t flags, usec_t rtt) {
 
         fputc('.', stdout);
         fputc('\n', stdout);
+
+        printf("-- Data is authenticated: %s\n", yes_no(flags & SD_RESOLVED_AUTHENTICATED));
 }
 
 static int resolve_host(sd_bus *bus, const char *name) {
diff --git a/src/resolve/resolved-bus.c b/src/resolve/resolved-bus.c
index ddde3af0c3..0ceca56371 100644
--- a/src/resolve/resolved-bus.c
+++ b/src/resolve/resolved-bus.c
@@ -197,7 +197,7 @@ static void bus_method_resolve_hostname_complete(DnsQuery *q) {
         r = sd_bus_message_append(
                         reply, "st",
                         DNS_RESOURCE_KEY_NAME(canonical->key),
-                        SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family));
+                        SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family, q->answer_authenticated));
         if (r < 0)
                 goto finish;
 
@@ -344,7 +344,7 @@ static void bus_method_resolve_address_complete(DnsQuery *q) {
         if (r < 0)
                 goto finish;
 
-        r = sd_bus_message_append(reply, "t", SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family));
+        r = sd_bus_message_append(reply, "t", SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family, q->answer_authenticated));
         if (r < 0)
                 goto finish;
 
@@ -510,7 +510,7 @@ static void bus_method_resolve_record_complete(DnsQuery *q) {
         if (r < 0)
                 goto finish;
 
-        r = sd_bus_message_append(reply, "t", SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family));
+        r = sd_bus_message_append(reply, "t", SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family, q->answer_authenticated));
         if (r < 0)
                 goto finish;
 
@@ -859,7 +859,7 @@ static void resolve_service_all_complete(DnsQuery *q) {
                         reply,
                         "ssst",
                         name, type, domain,
-                        SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family));
+                        SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family, q->answer_authenticated));
         if (r < 0)
                 goto finish;
 
diff --git a/src/resolve/resolved-conf.c b/src/resolve/resolved-conf.c
index 3fc7d9ae3d..1b2f3e336e 100644
--- a/src/resolve/resolved-conf.c
+++ b/src/resolve/resolved-conf.c
@@ -234,6 +234,41 @@ int config_parse_support(
         return 0;
 }
 
+int config_parse_dnssec(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        Manager *m = data;
+        DnssecMode mode;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        mode = dnssec_mode_from_string(rvalue);
+        if (mode < 0) {
+                r = parse_boolean(rvalue);
+                if (r < 0) {
+                        log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse DNSSEC mode '%s'. Ignoring.", rvalue);
+                        return 0;
+                }
+
+                mode = r ? DNSSEC_YES : DNSSEC_NO;
+        }
+
+        m->unicast_scope->dnssec_mode = mode;
+        return 0;
+}
+
 int manager_parse_config_file(Manager *m) {
         int r;
 
diff --git a/src/resolve/resolved-conf.h b/src/resolve/resolved-conf.h
index 28d2549d35..668ea02bba 100644
--- a/src/resolve/resolved-conf.h
+++ b/src/resolve/resolved-conf.h
@@ -36,3 +36,4 @@ const struct ConfigPerfItem* resolved_gperf_lookup(const char *key, unsigned len
 int config_parse_dns_servers(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_search_domains(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_support(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
+int config_parse_dnssec(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
diff --git a/src/resolve/resolved-def.h b/src/resolve/resolved-def.h
index be29f51663..db5ee57b51 100644
--- a/src/resolve/resolved-def.h
+++ b/src/resolve/resolved-def.h
@@ -28,6 +28,7 @@
 #define SD_RESOLVED_NO_TXT        (UINT64_C(1) << 6)
 #define SD_RESOLVED_NO_ADDRESS    (UINT64_C(1) << 7)
 #define SD_RESOLVED_NO_SEARCH     (UINT64_C(1) << 8)
+#define SD_RESOLVED_AUTHENTICATED (UINT64_C(1) << 9)
 
 #define SD_RESOLVED_LLMNR         (SD_RESOLVED_LLMNR_IPV4|SD_RESOLVED_LLMNR_IPV6)
 #define SD_RESOLVED_PROTOCOLS_ALL (SD_RESOLVED_LLMNR|SD_RESOLVED_DNS)
diff --git a/src/resolve/resolved-dns-cache.c b/src/resolve/resolved-dns-cache.c
index 3f34017789..bcb9994a8c 100644
--- a/src/resolve/resolved-dns-cache.c
+++ b/src/resolve/resolved-dns-cache.c
@@ -46,6 +46,7 @@ struct DnsCacheItem {
         usec_t until;
         DnsCacheItemType type;
         unsigned prioq_idx;
+        bool authenticated;
         int owner_family;
         union in_addr_union owner_address;
         LIST_FIELDS(DnsCacheItem, by_key);
@@ -237,7 +238,7 @@ static DnsCacheItem* dns_cache_get(DnsCache *c, DnsResourceRecord *rr) {
         return NULL;
 }
 
-static void dns_cache_item_update_positive(DnsCache *c, DnsCacheItem *i, DnsResourceRecord *rr, usec_t timestamp) {
+static void dns_cache_item_update_positive(DnsCache *c, DnsCacheItem *i, DnsResourceRecord *rr, bool authenticated, usec_t timestamp) {
         assert(c);
         assert(i);
         assert(rr);
@@ -257,6 +258,7 @@ static void dns_cache_item_update_positive(DnsCache *c, DnsCacheItem *i, DnsReso
         dns_resource_key_unref(i->key);
         i->key = dns_resource_key_ref(rr->key);
 
+        i->authenticated = authenticated;
         i->until = timestamp + MIN(rr->ttl * USEC_PER_SEC, CACHE_TTL_MAX_USEC);
 
         prioq_reshuffle(c->by_expiry, i, &i->prioq_idx);
@@ -265,6 +267,7 @@ static void dns_cache_item_update_positive(DnsCache *c, DnsCacheItem *i, DnsReso
 static int dns_cache_put_positive(
                 DnsCache *c,
                 DnsResourceRecord *rr,
+                bool authenticated,
                 usec_t timestamp,
                 int owner_family,
                 const union in_addr_union *owner_address) {
@@ -300,7 +303,7 @@ static int dns_cache_put_positive(
         /* Entry exists already? Update TTL and timestamp */
         existing = dns_cache_get(c, rr);
         if (existing) {
-                dns_cache_item_update_positive(c, existing, rr, timestamp);
+                dns_cache_item_update_positive(c, existing, rr, authenticated, timestamp);
                 return 0;
         }
 
@@ -322,6 +325,7 @@ static int dns_cache_put_positive(
         i->prioq_idx = PRIOQ_IDX_NULL;
         i->owner_family = owner_family;
         i->owner_address = *owner_address;
+        i->authenticated = authenticated;
 
         r = dns_cache_link_item(c, i);
         if (r < 0)
@@ -341,6 +345,7 @@ static int dns_cache_put_negative(
                 DnsCache *c,
                 DnsResourceKey *key,
                 int rcode,
+                bool authenticated,
                 usec_t timestamp,
                 uint32_t soa_ttl,
                 int owner_family,
@@ -389,6 +394,7 @@ static int dns_cache_put_negative(
         i->prioq_idx = PRIOQ_IDX_NULL;
         i->owner_family = owner_family;
         i->owner_address = *owner_address;
+        i->authenticated = authenticated;
 
         r = dns_cache_link_item(c, i);
         if (r < 0)
@@ -410,6 +416,7 @@ int dns_cache_put(
                 int rcode,
                 DnsAnswer *answer,
                 unsigned max_rrs,
+                bool authenticated,
                 usec_t timestamp,
                 int owner_family,
                 const union in_addr_union *owner_address) {
@@ -452,7 +459,7 @@ int dns_cache_put(
 
         /* Second, add in positive entries for all contained RRs */
         for (i = 0; i < MIN(max_rrs, answer->n_rrs); i++) {
-                r = dns_cache_put_positive(c, answer->items[i].rr, timestamp, owner_family, owner_address);
+                r = dns_cache_put_positive(c, answer->items[i].rr, authenticated, timestamp, owner_family, owner_address);
                 if (r < 0)
                         goto fail;
         }
@@ -496,13 +503,13 @@ int dns_cache_put(
                         if (!dns_answer_match_soa(canonical_key, soa->key))
                                 continue;
 
-                        r = dns_cache_put_negative(c, canonical_key, rcode, timestamp, MIN(soa->soa.minimum, soa->ttl), owner_family, owner_address);
+                        r = dns_cache_put_negative(c, canonical_key, rcode, authenticated, timestamp, MIN(soa->soa.minimum, soa->ttl), owner_family, owner_address);
                         if (r < 0)
                                 goto fail;
                 }
         }
 
-        r = dns_cache_put_negative(c, key, rcode, timestamp, MIN(soa->soa.minimum, soa->ttl), owner_family, owner_address);
+        r = dns_cache_put_negative(c, key, rcode, authenticated, timestamp, MIN(soa->soa.minimum, soa->ttl), owner_family, owner_address);
         if (r < 0)
                 goto fail;
 
@@ -522,7 +529,6 @@ fail:
 }
 
 static DnsCacheItem *dns_cache_get_by_key_follow_cname_dname_nsec(DnsCache *c, DnsResourceKey *k) {
-        _cleanup_(dns_resource_key_unrefp) DnsResourceKey *nsec_key = NULL, *cname_key = NULL;
         DnsCacheItem *i;
         const char *n;
         int r;
@@ -540,35 +546,23 @@ static DnsCacheItem *dns_cache_get_by_key_follow_cname_dname_nsec(DnsCache *c, D
         n = DNS_RESOURCE_KEY_NAME(k);
 
         /* Check if we have an NSEC record instead for the name. */
-        nsec_key = dns_resource_key_new(k->class, DNS_TYPE_NSEC, n);
-        if (!nsec_key)
-                return NULL;
-
-        i = hashmap_get(c->by_key, nsec_key);
+        i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_NSEC, n));
         if (i)
                 return i;
 
         /* Check if we have a CNAME record instead */
-        cname_key = dns_resource_key_new_cname(k);
-        if (!cname_key)
-                return NULL;
-        i = hashmap_get(c->by_key, cname_key);
+        i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_CNAME, n));
         if (i)
                 return i;
 
         /* OK, let's look for cached DNAME records. */
         for (;;) {
-                _cleanup_(dns_resource_key_unrefp) DnsResourceKey *dname_key = NULL;
                 char label[DNS_LABEL_MAX];
 
                 if (isempty(n))
                         return NULL;
 
-                dname_key = dns_resource_key_new(k->class, DNS_TYPE_DNAME, n);
-                if (!dname_key)
-                        return NULL;
-
-                i = hashmap_get(c->by_key, dname_key);
+                i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_DNAME, n));
                 if (i)
                         return i;
 
@@ -581,24 +575,26 @@ static DnsCacheItem *dns_cache_get_by_key_follow_cname_dname_nsec(DnsCache *c, D
         return NULL;
 }
 
-int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **ret) {
+int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **ret, bool *authenticated) {
         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
         unsigned n = 0;
         int r;
         bool nxdomain = false;
         _cleanup_free_ char *key_str = NULL;
-        DnsResourceRecord *nsec = NULL;
-        DnsCacheItem *j, *first;
+        DnsCacheItem *j, *first, *nsec = NULL;
+        bool have_authenticated = false, have_non_authenticated = false;
 
         assert(c);
         assert(key);
         assert(rcode);
         assert(ret);
+        assert(authenticated);
 
         if (key->type == DNS_TYPE_ANY ||
             key->class == DNS_CLASS_ANY) {
 
-                /* If we have ANY lookups we simply refresh */
+                /* If we have ANY lookups we don't use the cache, so
+                 * that the caller refreshes via the network. */
 
                 r = dns_resource_key_to_string(key, &key_str);
                 if (r < 0)
@@ -629,10 +625,16 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
         LIST_FOREACH(by_key, j, first) {
                 if (j->rr) {
                         if (j->rr->key->type == DNS_TYPE_NSEC)
-                                nsec = j->rr;
+                                nsec = j;
+
                         n++;
                 } else if (j->type == DNS_CACHE_NXDOMAIN)
                         nxdomain = true;
+
+                if (j->authenticated)
+                        have_authenticated = true;
+                else
+                        have_non_authenticated = true;
         }
 
         r = dns_resource_key_to_string(key, &key_str);
@@ -648,8 +650,11 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
 
                 *ret = NULL;
                 *rcode = DNS_RCODE_SUCCESS;
+                *authenticated = nsec->authenticated;
 
-                return !bitmap_isset(nsec->nsec.types, key->type);
+                return !bitmap_isset(nsec->rr->nsec.types, key->type) &&
+                       !bitmap_isset(nsec->rr->nsec.types, DNS_TYPE_CNAME) &&
+                       !bitmap_isset(nsec->rr->nsec.types, DNS_TYPE_DNAME);
         }
 
         log_debug("%s cache hit for %s",
@@ -660,6 +665,7 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
         if (n <= 0) {
                 *ret = NULL;
                 *rcode = nxdomain ? DNS_RCODE_NXDOMAIN : DNS_RCODE_SUCCESS;
+                *authenticated = have_authenticated && !have_non_authenticated;
                 return 1;
         }
 
@@ -678,6 +684,7 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
 
         *ret = answer;
         *rcode = DNS_RCODE_SUCCESS;
+        *authenticated = have_authenticated && !have_non_authenticated;
         answer = NULL;
 
         return n;
diff --git a/src/resolve/resolved-dns-cache.h b/src/resolve/resolved-dns-cache.h
index 561d31ad99..5f91164785 100644
--- a/src/resolve/resolved-dns-cache.h
+++ b/src/resolve/resolved-dns-cache.h
@@ -38,8 +38,8 @@ typedef struct DnsCache {
 void dns_cache_flush(DnsCache *c);
 void dns_cache_prune(DnsCache *c);
 
-int dns_cache_put(DnsCache *c, DnsResourceKey *key, int rcode, DnsAnswer *answer, unsigned max_rrs, usec_t timestamp, int owner_family, const union in_addr_union *owner_address);
-int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **answer);
+int dns_cache_put(DnsCache *c, DnsResourceKey *key, int rcode, DnsAnswer *answer, unsigned max_rrs, bool authenticated, usec_t timestamp, int owner_family, const union in_addr_union *owner_address);
+int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **answer, bool *authenticated);
 
 int dns_cache_check_conflicts(DnsCache *cache, DnsResourceRecord *rr, int owner_family, const union in_addr_union *owner_address);
 
diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c
index a32e938045..bb0e0ab3da 100644
--- a/src/resolve/resolved-dns-dnssec.c
+++ b/src/resolve/resolved-dns-dnssec.c
@@ -25,17 +25,34 @@
 #include "dns-domain.h"
 #include "resolved-dns-dnssec.h"
 #include "resolved-dns-packet.h"
+#include "string-table.h"
 
 /* Open question:
  *
  * How does the DNSSEC canonical form of a hostname with a label
  * containing a dot look like, the way DNS-SD does it?
  *
+ * TODO:
+ *
+ *   - Iterative validation
+ *   - NSEC proof of non-existance
+ *   - NSEC3 proof of non-existance
+ *   - Make trust anchor store read additional DS+DNSKEY data from disk
+ *   - wildcard zones compatibility
+ *   - multi-label zone compatibility
+ *   - DMSSEC cname/dname compatibility
+ *   - per-interface DNSSEC setting
+ *   - DSA support
+ *   - EC support?
+ *
  * */
 
 #define VERIFY_RRS_MAX 256
 #define MAX_KEY_SIZE (32*1024)
 
+/* Permit a maximum clock skew of 1h 10min. This should be enough to deal with DST confusion */
+#define SKEW_MAX (1*USEC_PER_HOUR + 10*USEC_PER_MINUTE)
+
 /*
  * The DNSSEC Chain of trust:
  *
@@ -228,10 +245,14 @@ static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) {
         inception = rrsig->rrsig.inception * USEC_PER_SEC;
 
         if (inception > expiration)
-                return -EINVAL;
+                return -EKEYREJECTED;
 
-        /* Permit a certain amount of clock skew of 10% of the valid time range */
+        /* Permit a certain amount of clock skew of 10% of the valid
+         * time range. This takes inspiration from unbound's
+         * resolver. */
         skew = (expiration - inception) / 10;
+        if (skew > SKEW_MAX)
+                skew = SKEW_MAX;
 
         if (inception < skew)
                 inception = 0;
@@ -690,3 +711,10 @@ finish:
         gcry_md_close(md);
         return r;
 }
+
+static const char* const dnssec_mode_table[_DNSSEC_MODE_MAX] = {
+        [DNSSEC_NO] = "no",
+        [DNSSEC_TRUST] = "trust",
+        [DNSSEC_YES] = "yes",
+};
+DEFINE_STRING_TABLE_LOOKUP(dnssec_mode, DnssecMode);
diff --git a/src/resolve/resolved-dns-dnssec.h b/src/resolve/resolved-dns-dnssec.h
index 8f812bc1fb..f4cb58988a 100644
--- a/src/resolve/resolved-dns-dnssec.h
+++ b/src/resolve/resolved-dns-dnssec.h
@@ -21,10 +21,26 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+typedef enum DnssecMode DnssecMode;
+
 #include "dns-domain.h"
 #include "resolved-dns-answer.h"
 #include "resolved-dns-rr.h"
 
+enum DnssecMode {
+        /* No DNSSEC validation is done */
+        DNSSEC_NO,
+
+        /* Trust the AD bit sent by the server. UNSAFE! */
+        DNSSEC_TRUST,
+
+        /* Validate locally, if the server knows DO, but if not, don't. Don't trust the AD bit */
+        DNSSEC_YES,
+
+        _DNSSEC_MODE_MAX,
+        _DNSSEC_MODE_INVALID = -1
+};
+
 enum {
         DNSSEC_VERIFIED,
         DNSSEC_INVALID,
@@ -33,7 +49,6 @@ enum {
         DNSSEC_SIGNATURE_EXPIRED,
 };
 
-
 #define DNSSEC_CANONICAL_HOSTNAME_MAX (DNS_HOSTNAME_MAX + 2)
 
 int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey);
@@ -47,3 +62,6 @@ int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds);
 uint16_t dnssec_keytag(DnsResourceRecord *dnskey);
 
 int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max);
+
+const char* dnssec_mode_to_string(DnssecMode m) _const_;
+DnssecMode dnssec_mode_from_string(const char *s) _pure_;
diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index 2a010ef507..ea776f7916 100644
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -65,7 +65,7 @@ int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
         return 0;
 }
 
-int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
+int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled) {
         DnsPacket *p;
         DnsPacketHeader *h;
         int r;
@@ -96,7 +96,7 @@ int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
                                                          1 /* rd (ask for recursion) */,
                                                          0 /* ra */,
                                                          0 /* ad */,
-                                                         0 /* cd */,
+                                                         dnssec_checking_disabled /* cd */,
                                                          0 /* rcode */));
 
         *ret = p;
diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h
index a6b88e6c79..aa2823cfb9 100644
--- a/src/resolve/resolved-dns-packet.h
+++ b/src/resolve/resolved-dns-packet.h
@@ -144,7 +144,7 @@ static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) {
 }
 
 int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu);
-int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu);
+int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled);
 
 DnsPacket *dns_packet_ref(DnsPacket *p);
 DnsPacket *dns_packet_unref(DnsPacket *p);
@@ -225,16 +225,19 @@ DnsProtocol dns_protocol_from_string(const char *s) _pure_;
 #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) })
 #define LLMNR_MULTICAST_IPV6_ADDRESS ((struct in6_addr) { .s6_addr = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x03 } })
 
-static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol, int family) {
+static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol, int family, bool authenticated) {
+        uint64_t f;
 
-        /* Converts a protocol + family into a flags field as used in queries */
+        /* Converts a protocol + family into a flags field as used in queries and responses */
+
+        f = authenticated ? SD_RESOLVED_AUTHENTICATED : 0;
 
         switch (protocol) {
         case DNS_PROTOCOL_DNS:
-                return SD_RESOLVED_DNS;
+                return f|SD_RESOLVED_DNS;
 
         case DNS_PROTOCOL_LLMNR:
-                return family == AF_INET6 ? SD_RESOLVED_LLMNR_IPV6 : SD_RESOLVED_LLMNR_IPV4;
+                return f|(family == AF_INET6 ? SD_RESOLVED_LLMNR_IPV6 : SD_RESOLVED_LLMNR_IPV4);
 
         default:
                 break;
diff --git a/src/resolve/resolved-dns-query.c b/src/resolve/resolved-dns-query.c
index 0f3a0dd21b..089d9fb70d 100644
--- a/src/resolve/resolved-dns-query.c
+++ b/src/resolve/resolved-dns-query.c
@@ -430,15 +430,17 @@ static int dns_query_add_candidate(DnsQuery *q, DnsScope *s) {
                 return r;
 
         /* If this a single-label domain on DNS, we might append a suitable search domain first. */
-        r = dns_scope_name_needs_search_domain(s, dns_question_first_name(q->question));
-        if (r < 0)
-                goto fail;
-        if (r > 0) {
-                /* OK, we need a search domain now. Let's find one for this scope */
-
-                r = dns_query_candidate_next_search_domain(c);
-                if (r <= 0) /* if there's no search domain, then we won't add any transaction. */
+        if ((q->flags & SD_RESOLVED_NO_SEARCH) == 0)  {
+                r = dns_scope_name_needs_search_domain(s, dns_question_first_name(q->question));
+                if (r < 0)
                         goto fail;
+                if (r > 0) {
+                        /* OK, we need a search domain now. Let's find one for this scope */
+
+                        r = dns_query_candidate_next_search_domain(c);
+                        if (r <= 0) /* if there's no search domain, then we won't add any transaction. */
+                                goto fail;
+                }
         }
 
         r = dns_query_candidate_setup_transactions(c);
@@ -970,6 +972,7 @@ static void dns_query_accept(DnsQuery *q, DnsQueryCandidate *c) {
         DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS;
         DnsTransaction *t;
         Iterator i;
+        bool has_authenticated = false, has_non_authenticated = false;
 
         assert(q);
 
@@ -997,6 +1000,11 @@ static void dns_query_accept(DnsQuery *q, DnsQueryCandidate *c) {
                         q->answer = merged;
                         q->answer_rcode = t->answer_rcode;
 
+                        if (t->answer_authenticated)
+                                has_authenticated = true;
+                        else
+                                has_non_authenticated = true;
+
                         state = DNS_TRANSACTION_SUCCESS;
                         break;
                 }
@@ -1026,6 +1034,7 @@ static void dns_query_accept(DnsQuery *q, DnsQueryCandidate *c) {
 
         q->answer_protocol = c->scope->protocol;
         q->answer_family = c->scope->family;
+        q->answer_authenticated = has_authenticated && !has_non_authenticated;
 
         dns_search_domain_unref(q->answer_search_domain);
         q->answer_search_domain = dns_search_domain_ref(c->search_domain);
diff --git a/src/resolve/resolved-dns-query.h b/src/resolve/resolved-dns-query.h
index a9d7904a8d..b71bb2352b 100644
--- a/src/resolve/resolved-dns-query.h
+++ b/src/resolve/resolved-dns-query.h
@@ -75,6 +75,7 @@ struct DnsQuery {
         DnsProtocol answer_protocol;
         int answer_family;
         DnsSearchDomain *answer_search_domain;
+        bool answer_authenticated;
 
         /* Bus client information */
         sd_bus_message *request;
diff --git a/src/resolve/resolved-dns-rr.c b/src/resolve/resolved-dns-rr.c
index 281e228b12..934a18334c 100644
--- a/src/resolve/resolved-dns-rr.c
+++ b/src/resolve/resolved-dns-rr.c
@@ -51,12 +51,6 @@ DnsResourceKey* dns_resource_key_new(uint16_t class, uint16_t type, const char *
         return k;
 }
 
-DnsResourceKey* dns_resource_key_new_cname(const DnsResourceKey *key) {
-        assert(key);
-
-        return dns_resource_key_new(key->class, DNS_TYPE_CNAME, DNS_RESOURCE_KEY_NAME(key));
-}
-
 DnsResourceKey* dns_resource_key_new_redirect(const DnsResourceKey *key, const DnsResourceRecord *cname) {
         int r;
 
@@ -137,6 +131,10 @@ DnsResourceKey* dns_resource_key_ref(DnsResourceKey *k) {
         if (!k)
                 return NULL;
 
+        /* Static/const keys created with DNS_RESOURCE_KEY_CONST will
+         * set this to -1, they should not be reffed/unreffed */
+        assert(k->n_ref != (unsigned) -1);
+
         assert(k->n_ref > 0);
         k->n_ref++;
 
@@ -147,6 +145,7 @@ DnsResourceKey* dns_resource_key_unref(DnsResourceKey *k) {
         if (!k)
                 return NULL;
 
+        assert(k->n_ref != (unsigned) -1);
         assert(k->n_ref > 0);
 
         if (k->n_ref == 1) {
@@ -158,6 +157,14 @@ DnsResourceKey* dns_resource_key_unref(DnsResourceKey *k) {
         return NULL;
 }
 
+bool dns_resource_key_is_address(const DnsResourceKey *key) {
+        assert(key);
+
+        /* Check if this is an A or AAAA resource key */
+
+        return key->class == DNS_CLASS_IN && IN_SET(key->type, DNS_TYPE_A, DNS_TYPE_AAAA);
+}
+
 int dns_resource_key_equal(const DnsResourceKey *a, const DnsResourceKey *b) {
         int r;
 
diff --git a/src/resolve/resolved-dns-rr.h b/src/resolve/resolved-dns-rr.h
index 2a103aab8d..b82fa77562 100644
--- a/src/resolve/resolved-dns-rr.h
+++ b/src/resolve/resolved-dns-rr.h
@@ -78,6 +78,19 @@ struct DnsResourceKey {
         char *_name; /* don't access directy, use DNS_RESOURCE_KEY_NAME()! */
 };
 
+/* Creates a temporary resource key. This is only useful to quickly
+ * look up something, without allocating a full DnsResourceKey object
+ * for it. Note that it is not OK to take references to this kind of
+ * resource key object. */
+#define DNS_RESOURCE_KEY_CONST(c, t, n)                 \
+        ((DnsResourceKey) {                             \
+                .n_ref = (unsigned) -1,                 \
+                .class = c,                             \
+                .type = t,                              \
+                ._name = (char*) n,                     \
+        })
+
+
 struct DnsTxtItem {
         size_t length;
         LIST_FIELDS(DnsTxtItem, items);
@@ -221,13 +234,12 @@ static inline const char* DNS_RESOURCE_KEY_NAME(const DnsResourceKey *key) {
 }
 
 DnsResourceKey* dns_resource_key_new(uint16_t class, uint16_t type, const char *name);
-DnsResourceKey* dns_resource_key_new_cname(const DnsResourceKey *key);
-DnsResourceKey* dns_resource_key_new_dname(const DnsResourceKey *key);
 DnsResourceKey* dns_resource_key_new_redirect(const DnsResourceKey *key, const DnsResourceRecord *cname);
 int dns_resource_key_new_append_suffix(DnsResourceKey **ret, DnsResourceKey *key, char *name);
 DnsResourceKey* dns_resource_key_new_consume(uint16_t class, uint16_t type, char *name);
 DnsResourceKey* dns_resource_key_ref(DnsResourceKey *key);
 DnsResourceKey* dns_resource_key_unref(DnsResourceKey *key);
+bool dns_resource_key_is_address(const DnsResourceKey *key);
 int dns_resource_key_equal(const DnsResourceKey *a, const DnsResourceKey *b);
 int dns_resource_key_match_rr(const DnsResourceKey *key, const DnsResourceRecord *rr, const char *search_domain);
 int dns_resource_key_match_cname(const DnsResourceKey *key, const DnsResourceRecord *rr, const char *search_domain);
diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c
index 846280e8b8..a90692cdf4 100644
--- a/src/resolve/resolved-dns-scope.c
+++ b/src/resolve/resolved-dns-scope.c
@@ -368,13 +368,14 @@ DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, co
         assert(s);
         assert(domain);
 
-        if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex))
-                return DNS_SCOPE_NO;
+        /* Checks if the specified domain is something to look up on
+         * this scope. Note that this accepts non-qualified hostnames,
+         * i.e. those without any search path prefixed yet. */
 
-        if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family) & flags) == 0)
+        if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex))
                 return DNS_SCOPE_NO;
 
-        if (dns_name_is_root(domain))
+        if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family, 0) & flags) == 0)
                 return DNS_SCOPE_NO;
 
         /* Never resolve any loopback hostname or IP address via DNS,
@@ -385,6 +386,12 @@ DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, co
             dns_name_equal(domain, "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0)
                 return DNS_SCOPE_NO;
 
+        /* Never respond to some of the domains listed in RFC6303 */
+        if (dns_name_endswith(domain, "0.in-addr.arpa") > 0 ||
+            dns_name_equal(domain, "255.255.255.255.in-addr.arpa") > 0 ||
+            dns_name_equal(domain, "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0)
+                return DNS_SCOPE_NO;
+
         /* Always honour search domains for routing queries. Note that
          * we return DNS_SCOPE_YES here, rather than just
          * DNS_SCOPE_MAYBE, which means wildcard scopes won't be
@@ -397,10 +404,12 @@ DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, co
 
         case DNS_PROTOCOL_DNS:
 
-                if ((!dns_name_is_single_label(domain) ||
-                     (!(flags & SD_RESOLVED_NO_SEARCH) && dns_scope_has_search_domains(s))) &&
-                    dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 &&
-                    dns_name_endswith(domain, "0.8.e.f.ip6.arpa") == 0)
+                /* Exclude link-local IP ranges */
+                if (dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 &&
+                    dns_name_endswith(domain, "8.e.f.ip6.arpa") == 0 &&
+                    dns_name_endswith(domain, "9.e.f.ip6.arpa") == 0 &&
+                    dns_name_endswith(domain, "a.e.f.ip6.arpa") == 0 &&
+                    dns_name_endswith(domain, "b.e.f.ip6.arpa") == 0)
                         return DNS_SCOPE_MAYBE;
 
                 return DNS_SCOPE_NO;
@@ -434,8 +443,27 @@ int dns_scope_good_key(DnsScope *s, DnsResourceKey *key) {
         assert(s);
         assert(key);
 
-        if (s->protocol == DNS_PROTOCOL_DNS)
-                return true;
+        /* Check if it makes sense to resolve the specified key on
+         * this scope. Note that this call assumes as fully qualified
+         * name, i.e. the search suffixes already appended. */
+
+        if (s->protocol == DNS_PROTOCOL_DNS) {
+
+                /* On classic DNS, lookin up non-address RRs is always
+                 * fine. (Specifically, we want to permit looking up
+                 * DNSKEY and DS records on the root and top-level
+                 * domains.) */
+                if (!dns_resource_key_is_address(key))
+                        return true;
+
+                /* However, we refuse to look up A and AAAA RRs on the
+                 * root and single-label domains, under the assumption
+                 * that those should be resolved via LLMNR or search
+                 * path only, and should not be leaked onto the
+                 * internet. */
+                return !(dns_name_is_single_label(DNS_RESOURCE_KEY_NAME(key)) ||
+                         dns_name_is_root(DNS_RESOURCE_KEY_NAME(key)));
+        }
 
         /* On mDNS and LLMNR, send A and AAAA queries only on the
          * respective scopes */
@@ -901,34 +929,13 @@ void dns_scope_dump(DnsScope *s, FILE *f) {
 DnsSearchDomain *dns_scope_get_search_domains(DnsScope *s) {
         assert(s);
 
-        /* Returns the list of *local* search domains -- not the
-         * global ones. */
-
         if (s->protocol != DNS_PROTOCOL_DNS)
                 return NULL;
 
         if (s->link)
                 return s->link->search_domains;
 
-        return NULL;
-}
-
-bool dns_scope_has_search_domains(DnsScope *s) {
-        assert(s);
-
-        /* Tests if there are *any* search domains suitable for this
-         * scope. This means either local or global ones */
-
-        if (s->protocol != DNS_PROTOCOL_DNS)
-                return false;
-
-        if (s->manager->search_domains)
-                return true;
-
-        if (s->link && s->link->search_domains)
-                return true;
-
-        return false;
+        return s->manager->search_domains;
 }
 
 bool dns_scope_name_needs_search_domain(DnsScope *s, const char *name) {
diff --git a/src/resolve/resolved-dns-scope.h b/src/resolve/resolved-dns-scope.h
index 0480f702f8..15d9a1fd6f 100644
--- a/src/resolve/resolved-dns-scope.h
+++ b/src/resolve/resolved-dns-scope.h
@@ -26,6 +26,7 @@
 typedef struct DnsScope DnsScope;
 
 #include "resolved-dns-cache.h"
+#include "resolved-dns-dnssec.h"
 #include "resolved-dns-packet.h"
 #include "resolved-dns-server.h"
 #include "resolved-dns-zone.h"
@@ -44,6 +45,7 @@ struct DnsScope {
 
         DnsProtocol protocol;
         int family;
+        DnssecMode dnssec_mode;
 
         Link *link;
 
@@ -102,6 +104,5 @@ void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p);
 void dns_scope_dump(DnsScope *s, FILE *f);
 
 DnsSearchDomain *dns_scope_get_search_domains(DnsScope *s);
-bool dns_scope_has_search_domains(DnsScope *s);
 
 bool dns_scope_name_needs_search_domain(DnsScope *s, const char *name);
diff --git a/src/resolve/resolved-dns-server.h b/src/resolve/resolved-dns-server.h
index 00366a48c9..b07fc3af3d 100644
--- a/src/resolve/resolved-dns-server.h
+++ b/src/resolve/resolved-dns-server.h
@@ -61,10 +61,11 @@ struct DnsServer {
         int family;
         union in_addr_union address;
 
+        bool marked:1;
+
         usec_t resend_timeout;
         usec_t max_rtt;
 
-        bool marked:1;
         DnsServerFeatureLevel verified_features;
         DnsServerFeatureLevel possible_features;
         size_t received_udp_packet_max;
diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c
index 90133cb332..1103a34c6f 100644
--- a/src/resolve/resolved-dns-transaction.c
+++ b/src/resolve/resolved-dns-transaction.c
@@ -481,20 +481,29 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
                 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);
-
         /* 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) {
                 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_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), 0, p->family, &p->sender);
+                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);
@@ -598,7 +607,7 @@ static int dns_transaction_make_packet(DnsTransaction *t) {
         if (t->sent)
                 return 0;
 
-        r = dns_packet_new_query(&p, t->scope->protocol, 0);
+        r = dns_packet_new_query(&p, t->scope->protocol, 0, t->scope->dnssec_mode == DNSSEC_YES);
         if (r < 0)
                 return r;
 
@@ -675,7 +684,21 @@ int dns_transaction_go(DnsTransaction *t) {
         t->answer_rcode = 0;
         t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID;
 
-        /* Check the zone, but obly if this transaction is not used
+        /* 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);
+                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;
+                }
+        }
+
+        /* Check the zone, but only if this transaction is not used
          * for probing or verifying a zone item. */
         if (set_isempty(t->zone_items)) {
 
@@ -685,6 +708,7 @@ int dns_transaction_go(DnsTransaction *t) {
                 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;
                 }
@@ -702,7 +726,7 @@ int dns_transaction_go(DnsTransaction *t) {
                 /* Let's then prune all outdated entries */
                 dns_cache_prune(&t->scope->cache);
 
-                r = dns_cache_lookup(&t->scope->cache, t->key, &t->answer_rcode, &t->answer);
+                r = dns_cache_lookup(&t->scope->cache, t->key, &t->answer_rcode, &t->answer, &t->answer_authenticated);
                 if (r < 0)
                         return r;
                 if (r > 0) {
@@ -817,5 +841,6 @@ static const char* const dns_transaction_source_table[_DNS_TRANSACTION_SOURCE_MA
         [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);
diff --git a/src/resolve/resolved-dns-transaction.h b/src/resolve/resolved-dns-transaction.h
index 5778913cc8..a3058ce6e8 100644
--- a/src/resolve/resolved-dns-transaction.h
+++ b/src/resolve/resolved-dns-transaction.h
@@ -44,6 +44,7 @@ enum DnsTransactionSource {
         DNS_TRANSACTION_NETWORK,
         DNS_TRANSACTION_CACHE,
         DNS_TRANSACTION_ZONE,
+        DNS_TRANSACTION_TRUST_ANCHOR,
         _DNS_TRANSACTION_SOURCE_MAX,
         _DNS_TRANSACTION_SOURCE_INVALID = -1
 };
@@ -68,6 +69,7 @@ struct DnsTransaction {
         DnsAnswer *answer;
         int answer_rcode;
         DnsTransactionSource answer_source;
+        bool answer_authenticated;
 
         usec_t start_usec;
         sd_event_source *timeout_event_source;
diff --git a/src/resolve/resolved-dns-trust-anchor.c b/src/resolve/resolved-dns-trust-anchor.c
new file mode 100644
index 0000000000..e55bdaa1ed
--- /dev/null
+++ b/src/resolve/resolved-dns-trust-anchor.c
@@ -0,0 +1,101 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2015 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 "alloc-util.h"
+#include "resolved-dns-trust-anchor.h"
+
+/* The DS RR from https://data.iana.org/root-anchors/root-anchors.xml */
+static const uint8_t root_digest[] =
+        { 0x49, 0xAA, 0xC1, 0x1D, 0x7B, 0x6F, 0x64, 0x46, 0x70, 0x2E, 0x54, 0xA1, 0x60, 0x73, 0x71, 0x60,
+          0x7A, 0x1A, 0x41, 0x85, 0x52, 0x00, 0xFD, 0x2C, 0xE1, 0xCD, 0xDE, 0x32, 0xF2, 0x4E, 0x8F, 0xB5 };
+
+int dns_trust_anchor_load(DnsTrustAnchor *d) {
+        _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+        _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+        int r;
+
+        assert(d);
+
+        r = hashmap_ensure_allocated(&d->by_key, &dns_resource_key_hash_ops);
+        if (r < 0)
+                return r;
+
+        if (hashmap_get(d->by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_DS, ".")))
+                return 0;
+
+        /* Add the RR from https://data.iana.org/root-anchors/root-anchors.xml */
+        rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DS, "");
+        if (!rr)
+                return -ENOMEM;
+
+        rr->ds.key_tag = 19036;
+        rr->ds.algorithm = DNSSEC_ALGORITHM_RSASHA256;
+        rr->ds.digest_type = DNSSEC_DIGEST_SHA256;
+        rr->ds.digest_size = sizeof(root_digest);
+        rr->ds.digest = memdup(root_digest, rr->ds.digest_size);
+        if (!rr->ds.digest)
+                return  -ENOMEM;
+
+        answer = dns_answer_new(1);
+        if (!answer)
+                return -ENOMEM;
+
+        r = dns_answer_add(answer, rr, 0);
+        if (r < 0)
+                return r;
+
+        r = hashmap_put(d->by_key, rr->key, answer);
+        if (r < 0)
+                return r;
+
+        answer = NULL;
+        return 0;
+}
+
+void dns_trust_anchor_flush(DnsTrustAnchor *d) {
+        DnsAnswer *a;
+
+        assert(d);
+
+        while ((a = hashmap_steal_first(d->by_key)))
+                dns_answer_unref(a);
+
+        d->by_key = hashmap_free(d->by_key);
+}
+
+int dns_trust_anchor_lookup(DnsTrustAnchor *d, DnsResourceKey *key, DnsAnswer **ret) {
+        DnsAnswer *a;
+
+        assert(d);
+        assert(key);
+        assert(ret);
+
+        /* We only serve DS and DNSKEY RRs. */
+        if (!IN_SET(key->type, DNS_TYPE_DS, DNS_TYPE_DNSKEY))
+                return 0;
+
+        a = hashmap_get(d->by_key, key);
+        if (!a)
+                return 0;
+
+        *ret = dns_answer_ref(a);
+        return 1;
+}
diff --git a/src/resolve/resolved-dns-trust-anchor.h b/src/resolve/resolved-dns-trust-anchor.h
new file mode 100644
index 0000000000..06f3723914
--- /dev/null
+++ b/src/resolve/resolved-dns-trust-anchor.h
@@ -0,0 +1,39 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2015 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/>.
+***/
+
+typedef struct DnsTrustAnchor DnsTrustAnchor;
+
+#include "hashmap.h"
+#include "resolved-dns-answer.h"
+#include "resolved-dns-rr.h"
+
+/* This contains a fixed database mapping domain names to DS or DNSKEY records. */
+
+struct DnsTrustAnchor {
+        Hashmap *by_key;
+};
+
+int dns_trust_anchor_load(DnsTrustAnchor *d);
+void dns_trust_anchor_flush(DnsTrustAnchor *d);
+
+int dns_trust_anchor_lookup(DnsTrustAnchor *d, DnsResourceKey* key, DnsAnswer **answer);
diff --git a/src/resolve/resolved-dns-zone.c b/src/resolve/resolved-dns-zone.c
index 493d11dd14..78f44d51a2 100644
--- a/src/resolve/resolved-dns-zone.c
+++ b/src/resolve/resolved-dns-zone.c
@@ -163,7 +163,6 @@ static int dns_zone_link_item(DnsZone *z, DnsZoneItem *i) {
 }
 
 static int dns_zone_item_probe_start(DnsZoneItem *i)  {
-        _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
         DnsTransaction *t;
         int r;
 
@@ -172,12 +171,14 @@ static int dns_zone_item_probe_start(DnsZoneItem *i)  {
         if (i->probe_transaction)
                 return 0;
 
-        key = dns_resource_key_new(i->rr->key->class, DNS_TYPE_ANY, DNS_RESOURCE_KEY_NAME(i->rr->key));
-        if (!key)
-                return -ENOMEM;
-
-        t = dns_scope_find_transaction(i->scope, key, false);
+        t = dns_scope_find_transaction(i->scope, &DNS_RESOURCE_KEY_CONST(i->rr->key->class, DNS_TYPE_ANY, DNS_RESOURCE_KEY_NAME(i->rr->key)), false);
         if (!t) {
+                _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
+
+                key = dns_resource_key_new(i->rr->key->class, DNS_TYPE_ANY, DNS_RESOURCE_KEY_NAME(i->rr->key));
+                if (!key)
+                        return -ENOMEM;
+
                 r = dns_transaction_new(&t, i->scope, key);
                 if (r < 0)
                         return r;
diff --git a/src/resolve/resolved-gperf.gperf b/src/resolve/resolved-gperf.gperf
index 50662656d5..c815eae850 100644
--- a/src/resolve/resolved-gperf.gperf
+++ b/src/resolve/resolved-gperf.gperf
@@ -18,3 +18,4 @@ Resolve.DNS,          config_parse_dns_servers,    DNS_SERVER_SYSTEM,   0
 Resolve.FallbackDNS,  config_parse_dns_servers,    DNS_SERVER_FALLBACK, 0
 Resolve.Domains,      config_parse_search_domains, 0,                   0
 Resolve.LLMNR,        config_parse_support,        0,                   offsetof(Manager, llmnr_support)
+Resolve.DNSSEC,       config_parse_dnssec,         0,                   0
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index 62562f0d24..5a3696ccb0 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -478,6 +478,10 @@ int manager_new(Manager **ret) {
         m->read_resolv_conf = true;
         m->need_builtin_fallbacks = true;
 
+        r = dns_trust_anchor_load(&m->trust_anchor);
+        if (r < 0)
+                return r;
+
         r = sd_event_default(&m->event);
         if (r < 0)
                 return r;
@@ -572,6 +576,8 @@ Manager *manager_free(Manager *m) {
         free(m->llmnr_hostname);
         free(m->mdns_hostname);
 
+        dns_trust_anchor_flush(&m->trust_anchor);
+
         free(m);
 
         return NULL;
diff --git a/src/resolve/resolved-manager.h b/src/resolve/resolved-manager.h
index d00c444583..1056f23ab7 100644
--- a/src/resolve/resolved-manager.h
+++ b/src/resolve/resolved-manager.h
@@ -44,6 +44,7 @@ enum Support {
 #include "resolved-dns-search-domain.h"
 #include "resolved-dns-server.h"
 #include "resolved-dns-stream.h"
+#include "resolved-dns-trust-anchor.h"
 #include "resolved-link.h"
 
 #define MANAGER_SEARCH_DOMAINS_MAX 32
@@ -85,6 +86,8 @@ struct Manager {
         bool read_resolv_conf:1;
         usec_t resolv_conf_mtime;
 
+        DnsTrustAnchor trust_anchor;
+
         LIST_HEAD(DnsScope, dns_scopes);
         DnsScope *unicast_scope;
 
diff --git a/src/resolve/resolved.conf.in b/src/resolve/resolved.conf.in
index 39ecf83217..efc9c6733a 100644
--- a/src/resolve/resolved.conf.in
+++ b/src/resolve/resolved.conf.in
@@ -16,3 +16,4 @@
 #FallbackDNS=@DNS_SERVERS@
 #Domains=
 #LLMNR=yes
+#DNSSEC=no