Merge branch '1703-tsig-verify-failure' into security-master

CHANGES

@@ -91,7 +91,9 @@
 			from the Git repository, run "autoreconf -fi" first.
 			[GL #4]
 
-5390.	[placeholder]
+5390.	[security]	Replaying a TSIG BADTIME response as a request could
+			trigger an assertion failure. (CVE-2020-8617)
+			[GL #1703]
 
 5389.	[bug]		Finish PKCS#11 code cleanup, fix a couple of smaller
 			bugs and use PKCS#11 v3.0 EdDSA macros and constants.

bin/tests/system/tsig/badtime

+# Transaction ID
+1122
+# Standard query
+0000
+# Questions: 1, Additional: 1
+0001 0000 0000 0001
+# QNAME: isc.org
+03 69 73 63 03 6F 72 67 00
+# Type: A (Host Address)
+0001
+# Class: IN
+0001
+# Specially crafted TSIG Resource Record
+# Name: "sha256"
+06 73 68 61 32 35 36 00
+# Type: TSIG (Transaction Signature)
+00fa
+# Class: ANY
+00ff
+# TTL: 0
+00000000
+# RdLen: 29
+001d
+# Algorithm Name: hmac-sha256
+0b 68 6D 61 63 2D 73 68 61 32 35 36 00
+# Time Signed: Jan 1, 1970 01:00:00.000000000 CET
+00 00 00 00 00 00
+# Fudge: 300
+012c
+# MAC Size: 0; MAC: empty
+0000
+# Original ID: 0
+0000
+# Error: BADSIG
+0010
+# Other Data Length: 0
+0000

bin/tests/system/tsig/tests.sh

@@ -212,5 +212,14 @@ ret=0
 $KEYGEN -a hmac-sha256 -b 128 -n host example.net > keygen.out3 2>&1 && ret=1
 grep "unknown algorithm" keygen.out3 > /dev/null || ret=1
 
+echo_i "check that a 'BADTIME' response with 'QR=0' is handled as a request"
+ret=0
+$PERL ../packet.pl -a 10.53.0.1 -p ${PORT} -t tcp < badtime > /dev/null
+$DIG -p ${PORT} @10.53.0.1 version.bind txt ch > dig.out.verify || ret=1
+grep "status: NOERROR" dig.out.verify > /dev/null || ret=1
+if [ $ret -eq 1 ] ; then
+    echo_i "failed"; status=1
+fi
+
 echo_i "exit status: $status"
 [ $status -eq 0 ] || exit 1

doc/notes/notes-current.rst

@@ -14,7 +14,8 @@ Notes for BIND 9.17.2
 Security Fixes
 ~~~~~~~~~~~~~~
 
--  None.
+-  Replaying a TSIG BADTIME response as a request could trigger an
+   assertion failure. This was disclosed in CVE-2020-8617. [GL #1703]
 
 Known Issues
 ~~~~~~~~~~~~

lib/dns/tsig.c

@@ -1360,8 +1360,8 @@ dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
 			goto cleanup_context;
 		}
 		msg->verified_sig = 1;
-	} else if (tsig.error != dns_tsigerror_badsig &&
-		   tsig.error != dns_tsigerror_badkey)
+	} else if (!response || (tsig.error != dns_tsigerror_badsig &&
+				 tsig.error != dns_tsigerror_badkey))
 	{
 		tsig_log(msg->tsigkey, 2, "signature was empty");
 		return (DNS_R_TSIGVERIFYFAILURE);
@@ -1409,7 +1409,7 @@ dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
 		}
 	}
 
-	if (tsig.error != dns_rcode_noerror) {
+	if (response && tsig.error != dns_rcode_noerror) {
 		msg->tsigstatus = tsig.error;
 		if (tsig.error == dns_tsigerror_badtime) {
 			ret = DNS_R_CLOCKSKEW;

util/copyrights

@@ -863,6 +863,7 @@
 ./bin/tests/system/tools/clean.sh		SH	2017,2018,2019,2020
 ./bin/tests/system/tools/setup.sh		SH	2019,2020
 ./bin/tests/system/tools/tests.sh		SH	2017,2018,2019,2020
+./bin/tests/system/tsig/badtime			X	2020
 ./bin/tests/system/tsig/clean.sh		SH	2005,2006,2007,2012,2014,2016,2018,2019,2020
 ./bin/tests/system/tsig/setup.sh		SH	2016,2017,2018,2019,2020
 ./bin/tests/system/tsig/tests.sh		SH	2005,2006,2007,2011,2012,2016,2018,2019,2020