]> git.ipfire.org Git - thirdparty/systemd.git/blobdiff - src/resolve/resolved-dns-dnssec.c
resolved: use dns_answer_size() where appropriate to handle NULL DnsAnswer
[thirdparty/systemd.git] / src / resolve / resolved-dns-dnssec.c
index a3aa90e98dcd8c1a6d55e2a8e109ad6667b234d5..e71939d99976dad842c640f4645b2cf2fcddf981 100644 (file)
  *
  * TODO:
  *
- *   - Make trust anchor store read additional DS+DNSKEY data from disk
  *   - wildcard zones compatibility (NSEC/NSEC3 wildcard check is missing)
  *   - multi-label zone compatibility
  *   - cname/dname compatibility
- *   - per-interface DNSSEC setting
  *   - nxdomain on qname
- *   - retry on failed validation?
- *   - DSA support?
+ *   - bus calls to override DNSEC setting per interface
+ *   - log all DNSSEC downgrades
+ *   - enable by default
  *
+ *   - RFC 4035, Section 5.3.4 (When receiving a positive wildcard reply, use NSEC to ensure it actually really applies)
+ *   - RFC 6840, Section 4.1 (ensure we don't get fed a glue NSEC from the parent zone)
+ *   - RFC 6840, Section 4.3 (check for CNAME on NSEC too)
  * */
 
 #define VERIFY_RRS_MAX 256
@@ -52,6 +54,9 @@
 /* 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)
 
+/* Maximum number of NSEC3 iterations we'll do. RFC5155 says 2500 shall be the maximum useful value */
+#define NSEC3_ITERATIONS_MAX 2500
+
 /*
  * The DNSSEC Chain of trust:
  *
@@ -76,9 +81,9 @@ static void initialize_libgcrypt(void) {
         gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
 }
 
-uint16_t dnssec_keytag(DnsResourceRecord *dnskey) {
+uint16_t dnssec_keytag(DnsResourceRecord *dnskey, bool mask_revoke) {
         const uint8_t *p;
-        uint32_t sum;
+        uint32_t sum, f;
         size_t i;
 
         /* The algorithm from RFC 4034, Appendix B. */
@@ -86,8 +91,12 @@ uint16_t dnssec_keytag(DnsResourceRecord *dnskey) {
         assert(dnskey);
         assert(dnskey->key->type == DNS_TYPE_DNSKEY);
 
-        sum = (uint32_t) dnskey->dnskey.flags +
-                ((((uint32_t) dnskey->dnskey.protocol) << 8) + (uint32_t) dnskey->dnskey.algorithm);
+        f = (uint32_t) dnskey->dnskey.flags;
+
+        if (mask_revoke)
+                f &= ~DNSKEY_FLAG_REVOKE;
+
+        sum = f + ((((uint32_t) dnskey->dnskey.protocol) << 8) + (uint32_t) dnskey->dnskey.algorithm);
 
         p = dnskey->dnskey.key;
 
@@ -113,15 +122,15 @@ static int rr_compare(const void *a, const void *b) {
         assert(*y);
         assert((*y)->wire_format);
 
-        m = MIN((*x)->wire_format_size, (*y)->wire_format_size);
+        m = MIN(DNS_RESOURCE_RECORD_RDATA_SIZE(*x), DNS_RESOURCE_RECORD_RDATA_SIZE(*y));
 
-        r = memcmp((*x)->wire_format, (*y)->wire_format, m);
+        r = memcmp(DNS_RESOURCE_RECORD_RDATA(*x), DNS_RESOURCE_RECORD_RDATA(*y), m);
         if (r != 0)
                 return r;
 
-        if ((*x)->wire_format_size < (*y)->wire_format_size)
+        if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) < DNS_RESOURCE_RECORD_RDATA_SIZE(*y))
                 return -1;
-        else if ((*x)->wire_format_size > (*y)->wire_format_size)
+        else if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) > DNS_RESOURCE_RECORD_RDATA_SIZE(*y))
                 return 1;
 
         return 0;
@@ -237,8 +246,8 @@ static int dnssec_rsa_verify(
 
                 exponent = (uint8_t*) dnskey->dnskey.key + 3;
                 exponent_size =
-                        ((size_t) (((uint8_t*) dnskey->dnskey.key)[0]) << 8) |
-                        ((size_t) ((uint8_t*) dnskey->dnskey.key)[1]);
+                        ((size_t) (((uint8_t*) dnskey->dnskey.key)[1]) << 8) |
+                        ((size_t) ((uint8_t*) dnskey->dnskey.key)[2]);
 
                 if (exponent_size < 256)
                         return -EINVAL;
@@ -458,7 +467,15 @@ static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) {
 
 static int algorithm_to_gcrypt_md(uint8_t algorithm) {
 
-        /* Translates a DNSSEC signature algorithm into a gcrypt digest identifier */
+        /* Translates a DNSSEC signature algorithm into a gcrypt
+         * digest identifier.
+         *
+         * Note that we implement all algorithms listed as "Must
+         * implement" and "Recommended to Implement" in RFC6944. We
+         * don't implement any algorithms that are listed as
+         * "Optional" or "Must Not Implement". Specifically, we do not
+         * implement RSAMD5, DSASHA1, DH, DSA-NSEC3-SHA1, and
+         * GOST-ECC. */
 
         switch (algorithm) {
 
@@ -483,7 +500,7 @@ static int algorithm_to_gcrypt_md(uint8_t algorithm) {
 
 int dnssec_verify_rrset(
                 DnsAnswer *a,
-                DnsResourceKey *key,
+                const DnsResourceKey *key,
                 DnsResourceRecord *rrsig,
                 DnsResourceRecord *dnskey,
                 usec_t realtime,
@@ -516,9 +533,6 @@ int dnssec_verify_rrset(
         if (md_algorithm < 0)
                 return md_algorithm;
 
-        if (a->n_rrs > VERIFY_RRS_MAX)
-                return -E2BIG;
-
         r = dnssec_rrsig_expired(rrsig, realtime);
         if (r < 0)
                 return r;
@@ -528,7 +542,7 @@ int dnssec_verify_rrset(
         }
 
         /* Collect all relevant RRs in a single array, so that we can look at the RRset */
-        list = newa(DnsResourceRecord *, a->n_rrs);
+        list = newa(DnsResourceRecord *, dns_answer_size(a));
 
         DNS_ANSWER_FOREACH(rr, a) {
                 r = dns_resource_key_equal(key, rr->key);
@@ -543,6 +557,9 @@ int dnssec_verify_rrset(
                         return r;
 
                 list[n++] = rr;
+
+                if (n > VERIFY_RRS_MAX)
+                        return -E2BIG;
         }
 
         if (n <= 0)
@@ -594,12 +611,11 @@ int dnssec_verify_rrset(
                 md_add_uint16(md, rr->key->class);
                 md_add_uint32(md, rrsig->rrsig.original_ttl);
 
-                assert(rr->wire_format_rdata_offset <= rr->wire_format_size);
-                l = rr->wire_format_size - rr->wire_format_rdata_offset;
+                l = DNS_RESOURCE_RECORD_RDATA_SIZE(rr);
                 assert(l <= 0xFFFF);
 
                 md_add_uint16(md, (uint16_t) l);
-                gcry_md_write(md, (uint8_t*) rr->wire_format + rr->wire_format_rdata_offset, l);
+                gcry_md_write(md, DNS_RESOURCE_RECORD_RDATA(rr), l);
         }
 
         hash = gcry_md_read(md, 0);
@@ -643,7 +659,7 @@ finish:
         return r;
 }
 
-int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey) {
+int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey, bool revoked_ok) {
 
         assert(rrsig);
         assert(dnskey);
@@ -660,12 +676,14 @@ int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnske
                 return 0;
         if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)
                 return 0;
+        if (!revoked_ok && (dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE))
+                return 0;
         if (dnskey->dnskey.protocol != 3)
                 return 0;
         if (dnskey->dnskey.algorithm != rrsig->rrsig.algorithm)
                 return 0;
 
-        if (dnssec_keytag(dnskey) != rrsig->rrsig.key_tag)
+        if (dnssec_keytag(dnskey, false) != rrsig->rrsig.key_tag)
                 return 0;
 
         return dns_name_equal(DNS_RESOURCE_KEY_NAME(dnskey->key), rrsig->rrsig.signer);
@@ -727,7 +745,7 @@ static int dnssec_fix_rrset_ttl(DnsAnswer *a, const DnsResourceKey *key, DnsReso
 
 int dnssec_verify_rrset_search(
                 DnsAnswer *a,
-                DnsResourceKey *key,
+                const DnsResourceKey *key,
                 DnsAnswer *validated_dnskeys,
                 usec_t realtime,
                 DnssecResult *result) {
@@ -766,7 +784,7 @@ int dnssec_verify_rrset_search(
                                 continue;
 
                         /* Is this a DNSKEY RR that matches they key of our RRSIG? */
-                        r = dnssec_rrsig_match_dnskey(rrsig, dnskey);
+                        r = dnssec_rrsig_match_dnskey(rrsig, dnskey, false);
                         if (r < 0)
                                 return r;
                         if (r == 0)
@@ -946,7 +964,7 @@ static int digest_to_gcrypt_md(uint8_t algorithm) {
         }
 }
 
-int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds) {
+int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds, bool mask_revoke) {
         char owner_name[DNSSEC_CANONICAL_HOSTNAME_MAX];
         gcry_md_hd_t md = NULL;
         size_t hash_size;
@@ -964,12 +982,14 @@ int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds) {
                 return -EINVAL;
         if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)
                 return -EKEYREJECTED;
+        if (!mask_revoke && (dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE))
+                return -EKEYREJECTED;
         if (dnskey->dnskey.protocol != 3)
                 return -EKEYREJECTED;
 
         if (dnskey->dnskey.algorithm != ds->ds.algorithm)
                 return 0;
-        if (dnssec_keytag(dnskey) != ds->ds.key_tag)
+        if (dnssec_keytag(dnskey, mask_revoke) != ds->ds.key_tag)
                 return 0;
 
         initialize_libgcrypt();
@@ -993,7 +1013,10 @@ int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds) {
                 return -EIO;
 
         gcry_md_write(md, owner_name, r);
-        md_add_uint16(md, dnskey->dnskey.flags);
+        if (mask_revoke)
+                md_add_uint16(md, dnskey->dnskey.flags & ~DNSKEY_FLAG_REVOKE);
+        else
+                md_add_uint16(md, dnskey->dnskey.flags);
         md_add_uint8(md, dnskey->dnskey.protocol);
         md_add_uint8(md, dnskey->dnskey.algorithm);
         gcry_md_write(md, dnskey->dnskey.key, dnskey->dnskey.key_size);
@@ -1038,7 +1061,9 @@ int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_
                 if (r == 0)
                         continue;
 
-                r = dnssec_verify_dnskey(dnskey, ds);
+                r = dnssec_verify_dnskey(dnskey, ds, false);
+                if (r == -EKEYREJECTED)
+                        return 0; /* The DNSKEY is revoked or otherwise invalid, we won't bless it */
                 if (r < 0)
                         return r;
                 if (r > 0)
@@ -1048,6 +1073,20 @@ int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_
         return 0;
 }
 
+static int nsec3_hash_to_gcrypt_md(uint8_t algorithm) {
+
+        /* Translates a DNSSEC NSEC3 hash algorithm into a gcrypt digest identifier */
+
+        switch (algorithm) {
+
+        case NSEC3_ALGORITHM_SHA1:
+                return GCRY_MD_SHA1;
+
+        default:
+                return -EOPNOTSUPP;
+        }
+}
+
 int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret) {
         uint8_t wire_format[DNS_WIRE_FOMAT_HOSTNAME_MAX];
         gcry_md_hd_t md = NULL;
@@ -1064,7 +1103,12 @@ int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret) {
         if (nsec3->key->type != DNS_TYPE_NSEC3)
                 return -EINVAL;
 
-        algorithm = digest_to_gcrypt_md(nsec3->nsec3.algorithm);
+        if (nsec3->nsec3.iterations > NSEC3_ITERATIONS_MAX) {
+                log_debug("Ignoring NSEC3 RR %s with excessive number of iterations.", dns_resource_record_to_string(nsec3));
+                return -EOPNOTSUPP;
+        }
+
+        algorithm = nsec3_hash_to_gcrypt_md(nsec3->nsec3.algorithm);
         if (algorithm < 0)
                 return algorithm;
 
@@ -1129,6 +1173,13 @@ static int nsec3_is_good(DnsResourceRecord *rr, DnsAnswerFlags flags, DnsResourc
         if (!IN_SET(rr->nsec3.flags, 0, 1))
                 return 0;
 
+        /* Ignore NSEC3 RRs whose algorithm we don't know */
+        if (nsec3_hash_to_gcrypt_md(rr->nsec3.algorithm) < 0)
+                return 0;
+        /* Ignore NSEC3 RRs with an excessive number of required iterations */
+        if (rr->nsec3.iterations > NSEC3_ITERATIONS_MAX)
+                return 0;
+
         if (!nsec3)
                 return 1;
 
@@ -1165,38 +1216,78 @@ static int nsec3_is_good(DnsResourceRecord *rr, DnsAnswerFlags flags, DnsResourc
         return dns_name_equal(a, b);
 }
 
-static int dnssec_test_nsec3(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated) {
-        _cleanup_free_ char *next_closer_domain = NULL, *l = NULL;
+static int nsec3_hashed_domain(DnsResourceRecord *nsec3, const char *domain, const char *zone, char **ret) {
+        _cleanup_free_ char *l = NULL, *hashed_domain = NULL;
         uint8_t hashed[DNSSEC_HASH_SIZE_MAX];
-        const char *suffix, *p, *pp = NULL;
-        DnsResourceRecord *rr, *suffix_rr;
+        int hashed_size;
+
+        assert(nsec3);
+        assert(domain);
+        assert(zone);
+        assert(ret);
+
+        hashed_size = dnssec_nsec3_hash(nsec3, domain, hashed);
+        if (hashed_size < 0)
+                return hashed_size;
+
+        l = base32hexmem(hashed, hashed_size, false);
+        if (!l)
+                return -ENOMEM;
+
+        hashed_domain = strjoin(l, ".", zone, NULL);
+        if (!hashed_domain)
+                return -ENOMEM;
+
+        *ret = hashed_domain;
+        hashed_domain = NULL;
+
+        return hashed_size;
+}
+
+/* See RFC 5155, Section 8
+ * First try to find a NSEC3 record that matches our query precisely, if that fails, find the closest
+ * enclosure. Secondly, find a proof that there is no closer enclosure and either a proof that there
+ * is no wildcard domain as a direct descendant of the closest enclosure, or find an NSEC3 record that
+ * matches the wildcard domain.
+ *
+ * Based on this we can prove either the existence of the record in @key, or NXDOMAIN or NODATA, or
+ * that there is no proof either way. The latter is the case if a the proof of non-existence of a given
+ * name uses an NSEC3 record with the opt-out bit set. Lastly, if we are given insufficient NSEC3 records
+ * to conclude anything we indicate this by returning NO_RR. */
+static int dnssec_test_nsec3(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) {
+        _cleanup_free_ char *next_closer_domain = NULL, *wildcard = NULL, *wildcard_domain = NULL;
+        const char *zone, *p, *pp = NULL;
+        DnsResourceRecord *rr, *enclosure_rr, *zone_rr, *wildcard_rr = NULL;
         DnsAnswerFlags flags;
         int hashed_size, r;
-        bool a;
+        bool a, no_closer = false, no_wildcard = false, optout = false;
 
         assert(key);
         assert(result);
-        assert(authenticated);
 
-        /* First step, look for the longest common suffix we find with any NSEC3 RR in the response. */
-        suffix = DNS_RESOURCE_KEY_NAME(key);
+        /* First step, find the zone name and the NSEC3 parameters of the zone.
+         * it is sufficient to look for the longest common suffix we find with
+         * any NSEC3 RR in the response. Any NSEC3 record will do as all NSEC3
+         * records from a given zone in a response must use the same
+         * parameters. */
+        zone = DNS_RESOURCE_KEY_NAME(key);
         for (;;) {
-                DNS_ANSWER_FOREACH_FLAGS(suffix_rr, flags, answer) {
-                        r = nsec3_is_good(suffix_rr, flags, NULL);
+                DNS_ANSWER_FOREACH_FLAGS(zone_rr, flags, answer) {
+                        r = nsec3_is_good(zone_rr, flags, NULL);
                         if (r < 0)
                                 return r;
                         if (r == 0)
                                 continue;
 
-                        r = dns_name_equal_skip(DNS_RESOURCE_KEY_NAME(suffix_rr->key), 1, suffix);
+                        r = dns_name_equal_skip(DNS_RESOURCE_KEY_NAME(zone_rr->key), 1, zone);
                         if (r < 0)
                                 return r;
                         if (r > 0)
-                                goto found_suffix;
+                                goto found_zone;
                 }
 
                 /* Strip one label from the front */
-                r = dns_name_parent(&suffix);
+                r = dns_name_parent(&zone);
                 if (r < 0)
                         return r;
                 if (r == 0)
@@ -1206,13 +1297,13 @@ static int dnssec_test_nsec3(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecR
         *result = DNSSEC_NSEC_NO_RR;
         return 0;
 
-found_suffix:
+found_zone:
         /* Second step, find the closest encloser NSEC3 RR in 'answer' that matches 'key' */
         p = DNS_RESOURCE_KEY_NAME(key);
         for (;;) {
-                _cleanup_free_ char *hashed_domain = NULL, *label = NULL;
+                _cleanup_free_ char *hashed_domain = NULL;
 
-                hashed_size = dnssec_nsec3_hash(suffix_rr, p, hashed);
+                hashed_size = nsec3_hashed_domain(zone_rr, p, zone, &hashed_domain);
                 if (hashed_size == -EOPNOTSUPP) {
                         *result = DNSSEC_NSEC_UNSUPPORTED_ALGORITHM;
                         return 0;
@@ -1220,26 +1311,18 @@ found_suffix:
                 if (hashed_size < 0)
                         return hashed_size;
 
-                label = base32hexmem(hashed, hashed_size, false);
-                if (!label)
-                        return -ENOMEM;
-
-                hashed_domain = strjoin(label, ".", suffix, NULL);
-                if (!hashed_domain)
-                        return -ENOMEM;
-
-                DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
+                DNS_ANSWER_FOREACH_FLAGS(enclosure_rr, flags, answer) {
 
-                        r = nsec3_is_good(rr, flags, suffix_rr);
+                        r = nsec3_is_good(enclosure_rr, flags, zone_rr);
                         if (r < 0)
                                 return r;
                         if (r == 0)
                                 continue;
 
-                        if (rr->nsec3.next_hashed_name_size != (size_t) hashed_size)
+                        if (enclosure_rr->nsec3.next_hashed_name_size != (size_t) hashed_size)
                                 continue;
 
-                        r = dns_name_equal(DNS_RESOURCE_KEY_NAME(rr->key), hashed_domain);
+                        r = dns_name_equal(DNS_RESOURCE_KEY_NAME(enclosure_rr->key), hashed_domain);
                         if (r < 0)
                                 return r;
                         if (r > 0) {
@@ -1269,42 +1352,56 @@ found_closest_encloser:
         /* We found a closest encloser in 'p'; next closer is 'pp' */
 
         /* Ensure this is not a DNAME domain, see RFC5155, section 8.3. */
-        if (bitmap_isset(rr->nsec3.types, DNS_TYPE_DNAME))
+        if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_DNAME))
                 return -EBADMSG;
 
         /* Ensure that this data is from the delegated domain
          * (i.e. originates from the "lower" DNS server), and isn't
          * just glue records (i.e. doesn't originate from the "upper"
          * DNS server). */
-        if (bitmap_isset(rr->nsec3.types, DNS_TYPE_NS) &&
-            !bitmap_isset(rr->nsec3.types, DNS_TYPE_SOA))
+        if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_NS) &&
+            !bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_SOA))
                 return -EBADMSG;
 
         if (!pp) {
                 /* No next closer NSEC3 RR. That means there's a direct NSEC3 RR for our key. */
-                *result = bitmap_isset(rr->nsec3.types, key->type) ? DNSSEC_NSEC_FOUND : DNSSEC_NSEC_NODATA;
-                *authenticated = a;
+                if (bitmap_isset(enclosure_rr->nsec3.types, key->type))
+                        *result = DNSSEC_NSEC_FOUND;
+                else if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_CNAME))
+                        *result = DNSSEC_NSEC_CNAME;
+                else
+                        *result = DNSSEC_NSEC_NODATA;
+
+                if (authenticated)
+                        *authenticated = a;
+                if (ttl)
+                        *ttl = enclosure_rr->ttl;
+
                 return 0;
         }
 
-        r = dnssec_nsec3_hash(rr, pp, hashed);
+        /* Prove that there is no next closer and whether or not there is a wildcard domain. */
+
+        wildcard = strappend("*.", p);
+        if (!wildcard)
+                return -ENOMEM;
+
+        r = nsec3_hashed_domain(enclosure_rr, wildcard, zone, &wildcard_domain);
         if (r < 0)
                 return r;
         if (r != hashed_size)
                 return -EBADMSG;
 
-        l = base32hexmem(hashed, hashed_size, false);
-        if (!l)
-                return -ENOMEM;
-
-        next_closer_domain = strjoin(l, ".", p, NULL);
-        if (!next_closer_domain)
-                return -ENOMEM;
+        r = nsec3_hashed_domain(enclosure_rr, pp, zone, &next_closer_domain);
+        if (r < 0)
+                return r;
+        if (r != hashed_size)
+                return -EBADMSG;
 
         DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
                 _cleanup_free_ char *label = NULL, *next_hashed_domain = NULL;
 
-                r = nsec3_is_good(rr, flags, suffix_rr);
+                r = nsec3_is_good(rr, flags, zone_rr);
                 if (r < 0)
                         return r;
                 if (r == 0)
@@ -1314,7 +1411,7 @@ found_closest_encloser:
                 if (!label)
                         return -ENOMEM;
 
-                next_hashed_domain = strjoin(label, ".", p, NULL);
+                next_hashed_domain = strjoin(label, ".", zone, NULL);
                 if (!next_hashed_domain)
                         return -ENOMEM;
 
@@ -1323,20 +1420,89 @@ found_closest_encloser:
                         return r;
                 if (r > 0) {
                         if (rr->nsec3.flags & 1)
-                                *result = DNSSEC_NSEC_OPTOUT;
-                        else
-                                *result = DNSSEC_NSEC_NXDOMAIN;
+                                optout = true;
 
-                        *authenticated = a && (flags & DNS_ANSWER_AUTHENTICATED);
-                        return 1;
+                        a = a && (flags & DNS_ANSWER_AUTHENTICATED);
+
+                        no_closer = true;
+                }
+
+                r = dns_name_equal(DNS_RESOURCE_KEY_NAME(rr->key), wildcard_domain);
+                if (r < 0)
+                        return r;
+                if (r > 0) {
+                        a = a && (flags & DNS_ANSWER_AUTHENTICATED);
+
+                        wildcard_rr = rr;
+                }
+
+                r = dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), wildcard_domain, next_hashed_domain);
+                if (r < 0)
+                        return r;
+                if (r > 0) {
+                        if (rr->nsec3.flags & 1)
+                                /* This only makes sense if we have a wildcard delegation, which is
+                                 * very unlikely, see RFC 4592, Section 4.2, but we cannot rely on
+                                 * this not happening, so hence cannot simply conclude NXDOMAIN as
+                                 * we would wish */
+                                optout = true;
+
+                        a = a && (flags & DNS_ANSWER_AUTHENTICATED);
+
+                        no_wildcard = true;
                 }
         }
 
-        *result = DNSSEC_NSEC_NO_RR;
+        if (wildcard_rr && no_wildcard)
+                return -EBADMSG;
+
+        if (!no_closer) {
+                *result = DNSSEC_NSEC_NO_RR;
+                return 0;
+        }
+
+        if (wildcard_rr) {
+                /* A wildcard exists that matches our query. */
+                if (optout)
+                        /* This is not specified in any RFC to the best of my knowledge, but
+                         * if the next closer enclosure is covered by an opt-out NSEC3 RR
+                         * it means that we cannot prove that the source of synthesis is
+                         * correct, as there may be a closer match. */
+                        *result = DNSSEC_NSEC_OPTOUT;
+                else if (bitmap_isset(wildcard_rr->nsec3.types, key->type))
+                        *result = DNSSEC_NSEC_FOUND;
+                else if (bitmap_isset(wildcard_rr->nsec3.types, DNS_TYPE_CNAME))
+                        *result = DNSSEC_NSEC_CNAME;
+                else
+                        *result = DNSSEC_NSEC_NODATA;
+        } else {
+                if (optout)
+                        /* The RFC only specifies that we have to care for optout for NODATA for
+                         * DS records. However, children of an insecure opt-out delegation should
+                         * also be considered opt-out, rather than verified NXDOMAIN.
+                         * Note that we do not require a proof of wildcard non-existence if the
+                         * next closer domain is covered by an opt-out, as that would not provide
+                         * any additional information. */
+                        *result = DNSSEC_NSEC_OPTOUT;
+                else if (no_wildcard)
+                        *result = DNSSEC_NSEC_NXDOMAIN;
+                else {
+                        *result = DNSSEC_NSEC_NO_RR;
+
+                        return 0;
+                }
+        }
+
+        if (authenticated)
+                *authenticated = a;
+
+        if (ttl)
+                *ttl = enclosure_rr->ttl;
+
         return 0;
 }
 
-int dnssec_test_nsec(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated) {
+int dnssec_test_nsec(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) {
         DnsResourceRecord *rr;
         bool have_nsec3 = false;
         DnsAnswerFlags flags;
@@ -1344,7 +1510,6 @@ int dnssec_test_nsec(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *r
 
         assert(key);
         assert(result);
-        assert(authenticated);
 
         /* Look for any NSEC/NSEC3 RRs that say something about the specified key. */
 
@@ -1361,8 +1526,18 @@ int dnssec_test_nsec(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *r
                         if (r < 0)
                                 return r;
                         if (r > 0) {
-                                *result = bitmap_isset(rr->nsec.types, key->type) ? DNSSEC_NSEC_FOUND : DNSSEC_NSEC_NODATA;
-                                *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
+                                if (bitmap_isset(rr->nsec.types, key->type))
+                                        *result = DNSSEC_NSEC_FOUND;
+                                else if (bitmap_isset(rr->nsec.types, DNS_TYPE_CNAME))
+                                        *result = DNSSEC_NSEC_CNAME;
+                                else
+                                        *result = DNSSEC_NSEC_NODATA;
+
+                                if (authenticated)
+                                        *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
+                                if (ttl)
+                                        *ttl = rr->ttl;
+
                                 return 0;
                         }
 
@@ -1371,7 +1546,12 @@ int dnssec_test_nsec(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *r
                                 return r;
                         if (r > 0) {
                                 *result = DNSSEC_NSEC_NXDOMAIN;
-                                *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
+
+                                if (authenticated)
+                                        *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
+                                if (ttl)
+                                        *ttl = rr->ttl;
+
                                 return 0;
                         }
                         break;
@@ -1384,20 +1564,13 @@ int dnssec_test_nsec(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *r
 
         /* OK, this was not sufficient. Let's see if NSEC3 can help. */
         if (have_nsec3)
-                return dnssec_test_nsec3(answer, key, result, authenticated);
+                return dnssec_test_nsec3(answer, key, result, authenticated, ttl);
 
         /* No approproate NSEC RR found, report this. */
         *result = DNSSEC_NSEC_NO_RR;
         return 0;
 }
 
-static const char* const dnssec_mode_table[_DNSSEC_MODE_MAX] = {
-        [DNSSEC_NO] = "no",
-        [DNSSEC_DOWNGRADE_OK] = "downgrade-ok",
-        [DNSSEC_YES] = "yes",
-};
-DEFINE_STRING_TABLE_LOOKUP(dnssec_mode, DnssecMode);
-
 static const char* const dnssec_result_table[_DNSSEC_RESULT_MAX] = {
         [DNSSEC_VALIDATED] = "validated",
         [DNSSEC_INVALID] = "invalid",