From: Mark Andrews <marka@isc.org>
Date: Mon, 1 Mar 2021 05:38:36 +0000 (+1100)
Subject: Check DNAME resolution via itself
X-Git-Tag: v9.17.14~8^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cbdea694e84e9ce7d112dd64230c8d1e2208b211;p=thirdparty%2Fbind9.git

Check DNAME resolution via itself
---

diff --git a/bin/tests/system/chain/ans3/ans.pl b/bin/tests/system/chain/ans3/ans.pl
index 13ee65edc46..31d22d807b7 100644
--- a/bin/tests/system/chain/ans3/ans.pl
+++ b/bin/tests/system/chain/ans3/ans.pl
@@ -80,6 +80,34 @@ sub reply_handler {
 	$rr = new Net::DNS::RR("$synth2 $ttl $qclass DNAME .");
 	push @ans, $rr;
 	$rcode = "NOERROR";
+    # The following three code branches referring to the "example.dname"
+    # zone are necessary for the resolver variant of the CVE-2021-25215
+    # regression test to work.  A named instance cannot be used for
+    # serving the DNAME records below as a version of BIND vulnerable to
+    # CVE-2021-25215 would crash while answering the queries asked by
+    # the tested resolver.
+    } elsif ($qname eq "ns3.example.dname") {
+	if ($qtype eq "A") {
+		my $rr = new Net::DNS::RR("$qname $ttl $qclass A 10.53.0.3");
+		push @ans, $rr;
+	}
+	if ($qtype eq "AAAA") {
+		my $rr = new Net::DNS::RR("example.dname. $ttl $qclass SOA . . 0 0 0 0 $ttl");
+		push @auth, $rr;
+	}
+	$rcode = "NOERROR";
+    } elsif ($qname eq "self.example.self.example.dname") {
+	my $rr = new Net::DNS::RR("self.example.dname. $ttl $qclass DNAME dname.");
+	push @ans, $rr;
+	$rr = new Net::DNS::RR("$qname $ttl $qclass CNAME self.example.dname.");
+	push @ans, $rr;
+	$rcode = "NOERROR";
+    } elsif ($qname eq "self.example.dname") {
+	if ($qtype eq "DNAME") {
+		my $rr = new Net::DNS::RR("$qname $ttl $qclass DNAME dname.");
+		push @ans, $rr;
+	}
+	$rcode = "NOERROR";
     } else {
 	$rcode = "REFUSED";
     }
diff --git a/bin/tests/system/chain/ns1/root.db b/bin/tests/system/chain/ns1/root.db
index bc70f8c2a0d..c076a77a1e1 100644
--- a/bin/tests/system/chain/ns1/root.db
+++ b/bin/tests/system/chain/ns1/root.db
@@ -24,6 +24,10 @@ ns2.example.		A	10.53.0.2
 example.broken.		NS	ns3.example.broken.
 ns3.example.broken.	A	10.53.0.3
 
+; for the resolver variant of the CVE-2021-25215 regression test
+example.dname.		NS	ns3.example.dname.
+ns3.example.dname.	A	10.53.0.3
+
 domain0.nil.		NS	ns2.domain0.nil
 domain1.nil.		NS	ns2.domain0.nil
 domain2.nil.		NS	ns2.domain0.nil
diff --git a/bin/tests/system/chain/ns2/generic.db b/bin/tests/system/chain/ns2/generic.db
index 8b9d2207dd9..566d22265b1 100644
--- a/bin/tests/system/chain/ns2/generic.db
+++ b/bin/tests/system/chain/ns2/generic.db
@@ -16,3 +16,5 @@ ns2	86400	AAAA    fd92:7065:b8e:ffff::2
 @       86400	AAAA 	1:2:3::4
 *       86400	A 	1.2.3.4
 *       86400	AAAA 	1:2:3::4
+; CVE-2021-25215 regression test data
+self	86400	DNAME	nil.
diff --git a/bin/tests/system/chain/tests.sh b/bin/tests/system/chain/tests.sh
index a7b2bf5d9f2..dc7622be6f0 100644
--- a/bin/tests/system/chain/tests.sh
+++ b/bin/tests/system/chain/tests.sh
@@ -295,5 +295,23 @@ grep 'status: NOERROR' dig.out.7.$n > /dev/null 2>&1 || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
 
+# Regression test for CVE-2021-25215 (authoritative server).
+n=`expr $n + 1`
+echo_i "checking DNAME resolution via itself (authoritative) ($n)"
+ret=0
+$DIG $DIGOPTS @10.53.0.2 DNAME self.domain0.self.domain0.nil. > dig.out.2.$n 2>&1
+grep 'status: NOERROR' dig.out.2.$n > /dev/null 2>&1 || ret=1
+if [ $ret != 0 ]; then echo_i "failed"; fi
+status=`expr $status + $ret`
+
+# Regression test for CVE-2021-25215 (recursive resolver).
+n=`expr $n + 1`
+echo_i "checking DNAME resolution via itself (recursive) ($n)"
+ret=0
+$DIG $DIGOPTS @10.53.0.7 DNAME self.example.self.example.dname. > dig.out.7.$n 2>&1
+grep 'status: NOERROR' dig.out.7.$n > /dev/null 2>&1 || ret=1
+if [ $ret != 0 ]; then echo_i "failed"; fi
+status=`expr $status + $ret`
+
 echo_i "exit status: $status"
 [ $status -eq 0 ] || exit 1