Merge branch '2517-cds-dnskey-delete-records-prevent-loading-unsigned-zone' into 'main'

Resolve "CDS and CDNSKEY DELETE records prevent (re-)loading unsigned zone"

Closes #2517

See merge request isc-projects/bind9!4810

CHANGES

@@ -1,3 +1,8 @@
+5606.	[bug]		CDS/CDNSKEY DELETE records were not removed when a zone
+			transitioned from secure to insecure. "named-checkzone"
+			should not complain if such records exist in an
+			unsigned zone. [GL #2517]
+
 5605.	[bug]		"dig -u" now uses CLOCK_REALTIME for more accurate
 			time reporting. [GL #2592]
 

bin/tests/system/checkzone/zones/good-cds-unsigned.db

@@ -0,0 +1,5 @@
+example.	0	SOA	. . 0 0 0 0 0
+example.	0	NS	.
+example.	0	CDS	0 0 0 00
+example.	0	CDNSKEY	0 3 0 AA==
+

bin/tests/system/kasp/tests.sh

@@ -3623,8 +3623,6 @@ check_next_key_event 93600
 set_zone "step2.going-insecure.kasp"
 set_policy "none" "2" "7200"
 set_server "ns6" "10.53.0.6"
-# Expect a CDS/CDNSKEY Delete Record.
-set_cdsdelete
 
 # The DS is long enough removed from the zone to be considered HIDDEN.
 # This means the DNSKEY and the KSK signatures can be removed.
@@ -3693,8 +3691,6 @@ set_zone "step2.going-insecure-dynamic.kasp"
 set_dynamic
 set_policy "none" "2" "7200"
 set_server "ns6" "10.53.0.6"
-# Expect a CDS/CDNSKEY Delete Record.
-set_cdsdelete
 
 # The DS is long enough removed from the zone to be considered HIDDEN.
 # This means the DNSKEY and the KSK signatures can be removed.

doc/notes/notes-current.rst

@@ -42,6 +42,10 @@ Bug Fixes
 - Dynamic zones with ``dnssec-policy`` that were frozen could not be thawed.
   This has been fixed. [GL #2523]
 
+- CDS/CDNSKEY DELETE records are now removed when a zone transitioned from
+  secure to insecure. "named-checkzone" no longer complains if such records
+  exist in an unsigned zone. [GL #2517]
+
 - Fix a crash when transferring a zone over TLS, after "named" previously
   skipped a master. [GL #2562]
 

lib/dns/zone.c

@@ -20123,7 +20123,12 @@ zone_rekey(dns_zone_t *zone) {
 	}
 
 	if (result == ISC_R_SUCCESS) {
-		bool insecure = dns_zone_secure_to_insecure(zone, false);
+		/*
+		 * Publish CDS/CDNSKEY DELETE records if the zone is
+		 * transitioning from secure to insecure.
+		 */
+		bool cds_delete = dns_zone_secure_to_insecure(zone, false);
+		isc_stdtime_t when;
 
 		/*
 		 * Only update DNSKEY TTL if we have a policy.
@@ -20160,9 +20165,36 @@ zone_rekey(dns_zone_t *zone) {
 			goto failure;
 		}
 
+		if (cds_delete) {
+			/*
+			 * Only publish CDS/CDNSKEY DELETE records if there is
+			 * a KSK that can be used to verify the RRset. This
+			 * means there must be a key with the KSK role that is
+			 * published and is used for signing.
+			 */
+			cds_delete = false;
+			for (key = ISC_LIST_HEAD(dnskeys); key != NULL;
+			     key = ISC_LIST_NEXT(key, link)) {
+				dst_key_t *dstk = key->key;
+				bool ksk = false;
+				(void)dst_key_getbool(dstk, DST_BOOL_KSK, &ksk);
+				if (!ksk) {
+					continue;
+				}
+
+				if (dst_key_haskasp(dstk) &&
+				    dst_key_is_published(dstk, now, &when) &&
+				    dst_key_is_signing(dstk, DST_BOOL_KSK, now,
+						       &when))
+				{
+					cds_delete = true;
+					break;
+				}
+			}
+		}
 		result = dns_dnssec_syncdelete(&cdsset, &cdnskeyset,
 					       &zone->origin, zone->rdclass,
-					       ttl, &diff, mctx, insecure);
+					       ttl, &diff, mctx, cds_delete);
 		if (result != ISC_R_SUCCESS) {
 			dnssec_log(zone, ISC_LOG_ERROR,
 				   "zone_rekey:couldn't update CDS/CDNSKEY "
@@ -20524,6 +20556,7 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 	unsigned char buffer[DNS_DS_BUFFERSIZE];
 	unsigned char algorithms[256];
 	unsigned int i;
+	bool empty = false;
 
 	enum { notexpected = 0, expected = 1, found = 2 };
 
@@ -20559,14 +20592,8 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 	result = dns_db_findrdataset(db, node, version, dns_rdatatype_dnskey,
 				     dns_rdatatype_none, 0, &dnskey, NULL);
 	if (result == ISC_R_NOTFOUND) {
-		if (dns_rdataset_isassociated(&cds)) {
-			result = DNS_R_BADCDS;
-		} else {
-			result = DNS_R_BADCDNSKEY;
-		}
-		goto failure;
-	}
-	if (result != ISC_R_SUCCESS) {
+		empty = true;
+	} else if (result != ISC_R_SUCCESS) {
 		goto failure;
 	}
 
@@ -20596,6 +20623,12 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 				delete = true;
 				continue;
 			}
+
+			if (empty) {
+				result = DNS_R_BADCDS;
+				goto failure;
+			}
+
 			CHECK(dns_rdata_tostruct(&crdata, &structcds, NULL));
 			if (algorithms[structcds.algorithm] == 0) {
 				algorithms[structcds.algorithm] = expected;
@@ -20663,6 +20696,12 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 				delete = true;
 				continue;
 			}
+
+			if (empty) {
+				result = DNS_R_BADCDNSKEY;
+				goto failure;
+			}
+
 			CHECK(dns_rdata_tostruct(&crdata, &structcdnskey,
 						 NULL));
 			if (algorithms[structcdnskey.algorithm] == 0) {