bind: CVE-2015-8000

Fixes a denial of service in BIND.

An error in the parsing of incoming responses allows some
records with an incorrect class to be accepted by BIND
instead of being rejected as malformed. This can trigger
a REQUIRE assertion failure when those records are subsequently
cached.

[YOCTO #8838]

References:
http://www.openwall.com/lists/oss-security/2015/12/15/14
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-8000
https://bugzilla.redhat.com/attachment.cgi?id=1105581

Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

2 files changed, 195 insertions, 0 deletions

diff --git a/meta/recipes-connectivity/bind/bind/CVE-2015-8000.patch b/meta/recipes-connectivity/bind/bind/CVE-2015-8000.patch
new file mode 100644
index 0000000000..b8d841206f
--- /dev/null
+++ b/meta/recipes-connectivity/bind/bind/CVE-2015-8000.patch
@@ -0,0 +1,194 @@
+responses with a malformed class attribute can trigger an
+assertion failure in db.c
+
+[security]
+Insufficient testing when parsing a message allowed records with
+an incorrect class to be be accepted, triggering a REQUIRE failure
+when those records were subsequently cached. (CVE-2015-8000) [RT#4098]
+
+Upstream-Status: Backport
+
+[The patch is taken from BIND 9.9.4:
+https://bugzilla.redhat.com/attachment.cgi?id=1105581]
+
+Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
+---
+diff --git a/lib/dns/include/dns/message.h b/lib/dns/include/dns/message.h
+index a6862fa..d999e75 100644
+--- a/lib/dns/include/dns/message.h
++++ b/lib/dns/include/dns/message.h
+@@ -210,6 +210,8 @@ struct dns_message {
+ 	unsigned int			verify_attempted : 1;
+ 	unsigned int			free_query : 1;
+ 	unsigned int			free_saved : 1;
++	unsigned int			tkey : 1;
++	unsigned int			rdclass_set : 1;
+ 
+ 	unsigned int			opt_reserved;
+ 	unsigned int			sig_reserved;
+@@ -1374,6 +1376,15 @@ dns_message_buildopt(dns_message_t *msg, dns_rdataset_t **opt,
+  * \li	 other.
+  */
+ 
++void
++dns_message_setclass(dns_message_t *msg, dns_rdataclass_t rdclass);
++/*%<
++ * Set the expected class of records in the response.
++ *
++ * Requires:
++ * \li   msg be a valid message with parsing intent.
++ */
++
+ ISC_LANG_ENDDECLS
+ 
+ #endif /* DNS_MESSAGE_H */
+diff --git a/lib/dns/message.c b/lib/dns/message.c
+index 53efc5a..73def73 100644
+--- a/lib/dns/message.c
++++ b/lib/dns/message.c
+@@ -436,6 +436,8 @@ msginit(dns_message_t *m) {
+ 	m->saved.base = NULL;
+ 	m->saved.length = 0;
+ 	m->free_saved = 0;
++	m->tkey = 0;
++	m->rdclass_set = 0;
+ 	m->querytsig = NULL;
+ }
+ 
+@@ -1086,13 +1088,19 @@ getquestions(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ 		 * If this class is different than the one we already read,
+ 		 * this is an error.
+ 		 */
+-		if (msg->state == DNS_SECTION_ANY) {
+-			msg->state = DNS_SECTION_QUESTION;
++		if (msg->rdclass_set == 0) {
+ 			msg->rdclass = rdclass;
++			msg->rdclass_set = 1;
+ 		} else if (msg->rdclass != rdclass)
+ 			DO_FORMERR;
+ 
+ 		/*
++		 * Is this a TKEY query?
++		 */
++		if (rdtype == dns_rdatatype_tkey)
++			msg->tkey = 1;
++
++		/*
+ 		 * Can't ask the same question twice.
+ 		 */
+ 		result = dns_message_find(name, rdclass, rdtype, 0, NULL);
+@@ -1236,12 +1244,12 @@ getsection(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ 		 * If there was no question section, we may not yet have
+ 		 * established a class.  Do so now.
+ 		 */
+-		if (msg->state == DNS_SECTION_ANY &&
++		if (msg->rdclass_set == 0 &&
+ 		    rdtype != dns_rdatatype_opt &&	/* class is UDP SIZE */
+ 		    rdtype != dns_rdatatype_tsig &&	/* class is ANY */
+ 		    rdtype != dns_rdatatype_tkey) {	/* class is undefined */
+ 			msg->rdclass = rdclass;
+-			msg->state = DNS_SECTION_QUESTION;
++			msg->rdclass_set = 1;
+ 		}
+ 
+ 		/*
+@@ -1251,7 +1259,7 @@ getsection(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ 		if (msg->opcode != dns_opcode_update
+ 		    && rdtype != dns_rdatatype_tsig
+ 		    && rdtype != dns_rdatatype_opt
+-		    && rdtype != dns_rdatatype_dnskey /* in a TKEY query */
++		    && rdtype != dns_rdatatype_key /* in a TKEY query */
+ 		    && rdtype != dns_rdatatype_sig /* SIG(0) */
+ 		    && rdtype != dns_rdatatype_tkey /* Win2000 TKEY */
+ 		    && msg->rdclass != dns_rdataclass_any
+@@ -1259,6 +1267,16 @@ getsection(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ 			DO_FORMERR;
+ 
+ 		/*
++		 * If this is not a TKEY query/response then the KEY
++		 * record's class needs to match.
++		 */
++		if (msg->opcode != dns_opcode_update && !msg->tkey &&
++		    rdtype == dns_rdatatype_key &&
++		    msg->rdclass != dns_rdataclass_any &&
++		    msg->rdclass != rdclass)
++			DO_FORMERR;
++
++		/*
+ 		 * Special type handling for TSIG, OPT, and TKEY.
+ 		 */
+ 		if (rdtype == dns_rdatatype_tsig) {
+@@ -1372,6 +1390,10 @@ getsection(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
+ 				skip_name_search = ISC_TRUE;
+ 				skip_type_search = ISC_TRUE;
+ 				issigzero = ISC_TRUE;
++			} else {
++				if (msg->rdclass != dns_rdataclass_any &&
++				    msg->rdclass != rdclass)
++					DO_FORMERR;
+ 			}
+ 		} else
+ 			covers = 0;
+@@ -1610,6 +1632,7 @@ dns_message_parse(dns_message_t *msg, isc_buffer_t *source,
+ 	msg->counts[DNS_SECTION_ADDITIONAL] = isc_buffer_getuint16(source);
+ 
+ 	msg->header_ok = 1;
++	msg->state = DNS_SECTION_QUESTION;
+ 
+ 	/*
+ 	 * -1 means no EDNS.
+@@ -3550,3 +3573,15 @@ dns_message_buildopt(dns_message_t *message, dns_rdataset_t **rdatasetp,
+ 		dns_message_puttemprdatalist(message, &rdatalist);
+ 	return (result);
+ }
++
++void
++dns_message_setclass(dns_message_t *msg, dns_rdataclass_t rdclass) {
++
++	REQUIRE(DNS_MESSAGE_VALID(msg));
++	REQUIRE(msg->from_to_wire == DNS_MESSAGE_INTENTPARSE);
++	REQUIRE(msg->state == DNS_SECTION_ANY);
++	REQUIRE(msg->rdclass_set == 0);
++
++	msg->rdclass = rdclass;
++	msg->rdclass_set = 1;
++}
+diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
+index aa23b11..d220986 100644
+--- a/lib/dns/resolver.c
++++ b/lib/dns/resolver.c
+@@ -6964,6 +6964,8 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
+ 			goto done;
+ 	}
+ 
++	dns_message_setclass(message, fctx->res->rdclass);
++
+ 	result = dns_message_parse(message, &devent->buffer, 0);
+ 	if (result != ISC_R_SUCCESS) {
+ 		switch (result) {
+@@ -7036,6 +7038,12 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
+ 	 */
+ 	log_packet(message, ISC_LOG_DEBUG(10), fctx->res->mctx);
+ 
++	if (message->rdclass != fctx->res->rdclass) {
++		resend = ISC_TRUE;
++		FCTXTRACE("bad class");
++		goto done;
++	}
++
+ 	/*
+ 	 * Process receive opt record.
+ 	 */
+diff --git a/lib/dns/xfrin.c b/lib/dns/xfrin.c
+index 9ad8960..938373a 100644
+--- a/lib/dns/xfrin.c
++++ b/lib/dns/xfrin.c
+@@ -1241,6 +1241,8 @@ xfrin_recv_done(isc_task_t *task, isc_event_t *ev) {
+ 	msg->tsigctx = xfr->tsigctx;
+ 	xfr->tsigctx = NULL;
+ 
++	dns_message_setclass(msg, xfr->rdclass);
++
+ 	if (xfr->nmsg > 0)
+ 		msg->tcp_continuation = 1;
+ 
diff --git a/meta/recipes-connectivity/bind/bind_9.9.5.bb b/meta/recipes-connectivity/bind/bind_9.9.5.bb
index ee940112f7..6e4878d06b 100644
--- a/meta/recipes-connectivity/bind/bind_9.9.5.bb
+++ b/meta/recipes-connectivity/bind/bind_9.9.5.bb
@@ -22,6 +22,7 @@ SRC_URI = "ftp://ftp.isc.org/isc/bind9/${PV}/${BPN}-${PV}.tar.gz \
 	   file://CVE-2015-1349.patch \ 
 	   file://CVE-2015-4620.patch \
 	   file://CVE-2015-5722.patch \
+           file://CVE-2015-8000.patch \
 	   "
 
 SRC_URI[md5sum] = "e676c65cad5234617ee22f48e328c24e"