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Add advisory and patches for SA-15:27.bind.

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Xin LI 2015-12-16 06:28:03 +00:00
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Notes: svn2git 2020-12-08 03:00:23 +00:00 
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share/security/advisories/FreeBSD-SA-15:27.bind.asc Normal file
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
=============================================================================
FreeBSD-SA-15:27.bind Security Advisory
The FreeBSD Project
Topic: BIND remote denial of service vulnerability
Category: contrib
Module: bind
Announced: 2015-12-16
Credits: ISC
Affects: FreeBSD 9.x
Corrected: 2015-12-16 06:10:05 UTC (stable/9, 9.3-STABLE)
2015-12-16 06:21:26 UTC (releng/9.3, 9.3-RELEASE-p32)
CVE Name: CVE-2015-8000
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:https://security.FreeBSD.org/>.
I. Background
BIND 9 is an implementation of the Domain Name System (DNS) protocols.
The named(8) daemon is an Internet Domain Name Server. The libdns
library is a library of DNS protocol support functions.
II. Problem Description
An error in the parsing of incoming responses allows some records with an
incorrect class to be be accepted by BIND instead of being rejected as
malformed. This can trigger a REQUIRE assertion failure when those records
are subsequently cached.
III. Impact
An attacker who can cause a server to request a record with a malformed class
attribute can use this bug to trigger a REQUIRE assertion in db.c, causing
named to exit and denying service to clients.
The risk to recursive servers is high. Authoritative servers are at limited
risk if they perform authentication when making recursive queries to resolve
addresses for servers listed in NS RRSETs.
IV. Workaround
No workaround is available, but hosts not running named(8) are not
vulnerable.
V. Solution
Perform one of the following:
1) Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date.
The named service has to be restarted after the update. A reboot is
recommended but not required.
2) To update your vulnerable system via a binary patch:
Systems running a RELEASE version of FreeBSD on the i386 or amd64
platforms can be updated via the freebsd-update(8) utility:
# freebsd-update fetch
# freebsd-update install
The named service has to be restarted after the update. A reboot is
recommended but not required.
3) To update your vulnerable system via a source code patch:
The following patches have been verified to apply to the applicable
FreeBSD release branches.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
[FreeBSD 9.3]
# fetch https://security.FreeBSD.org/patches/SA-15:27/bind.patch
# fetch https://security.FreeBSD.org/patches/SA-15:27/bind.patch.asc
# gpg --verify bind.patch.asc
b) Apply the patch. Execute the following commands as root:
# cd /usr/src
# patch < /path/to/patch
c) Recompile the operating system using buildworld and installworld as
described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.
Restart the applicable daemons, or reboot the system.
VI. Correction details
The following list contains the correction revision numbers for each
affected branch.
Branch/path Revision
- -------------------------------------------------------------------------
stable/9/ r292320
releng/9.3/ r292321
- -------------------------------------------------------------------------
To see which files were modified by a particular revision, run the
following command, replacing NNNNNN with the revision number, on a
machine with Subversion installed:
# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
Or visit the following URL, replacing NNNNNN with the revision number:
<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
VII. References
<URL:https://kb.isc.org/article/AA-01317>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-8000>
The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-15:27.bind.asc>
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share/security/patches/SA-15:27/bind.patch Normal file
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Index: contrib/bind9/lib/dns/include/dns/message.h
===================================================================
--- contrib/bind9/lib/dns/include/dns/message.h (revision 292253)
+++ contrib/bind9/lib/dns/include/dns/message.h (working copy)
@@ -15,8 +15,6 @@
* PERFORMANCE OF THIS SOFTWARE.
*/
-/* $Id$ */
-
#ifndef DNS_MESSAGE_H
#define DNS_MESSAGE_H 1
@@ -211,6 +209,8 @@ 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;
@@ -1375,6 +1375,15 @@ dns_message_buildopt(dns_message_t *msg, dns_rdata
* \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 */
Index: contrib/bind9/lib/dns/message.c
===================================================================
--- contrib/bind9/lib/dns/message.c (revision 292253)
+++ contrib/bind9/lib/dns/message.c (working copy)
@@ -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 *
* 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 *ms
* 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 *ms
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 *ms
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 *ms
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
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_r
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;
+}
Index: contrib/bind9/lib/dns/resolver.c
===================================================================
--- contrib/bind9/lib/dns/resolver.c (revision 292253)
+++ contrib/bind9/lib/dns/resolver.c (working copy)
@@ -6941,6 +6941,8 @@ resquery_response(isc_task_t *task, isc_event_t *e
goto done;
}
+ dns_message_setclass(message, fctx->res->rdclass);
+
result = dns_message_parse(message, &devent->buffer, 0);
if (result != ISC_R_SUCCESS) {
switch (result) {
@@ -7013,6 +7015,12 @@ resquery_response(isc_task_t *task, isc_event_t *e
*/
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.
*/
Index: contrib/bind9/lib/dns/xfrin.c
===================================================================
--- contrib/bind9/lib/dns/xfrin.c (revision 292253)
+++ contrib/bind9/lib/dns/xfrin.c (working copy)
@@ -1211,6 +1211,8 @@ 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;

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share/xml/advisories.xml
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<month>
<name>12</name>
<day>
<name>26</name>
<advisory>
<name>FreeBSD-SA-15:27.bind</name>
</advisory>
</day>
<day>
<name>6</name>