[v9_11] address TSIG bypass/forgery vulnerabilities

4643.	[security]	An error in TSIG handling could permit unauthorized
			zone transfers or zone updates. (CVE-2017-3142)
			(CVE-2017-3143) [RT #45383]

(cherry picked from commit 581c1526ab0f74a177980da9ff0514f795ed8669)

diff --git a/CHANGES b/CHANGES
index 02605a632bcc490c4b942db5b95fa5342bd49c9f..79064a17ee5a5b9a31f3b20ede307667a215f4b7 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,5 +1,9 @@
        --- 9.11.2b1 released ---
 
+4643.  [security]      An error in TSIG handling could permit unauthorized
+                       zone transfers or zone updates. (CVE-2017-3142)
+                       (CVE-2017-3143) [RT #45383]
+
 4642.  [cleanup]       Add more logging of RFC 5011 events affecting the
                        status of managed keys: newly observed keys,
                        deletion of revoked keys, etc. [RT #45354]

diff --git a/README b/README
index c0228f401494043038c54fc4781fb363b346e072..ce10a26762e2cd0f613edc727bb2d022e5b16c34 100644 (file)
--- a/README
+++ b/README
@@ -224,10 +224,11 @@ and CVE-2017-3138.
 
 BIND 9.11.2
 
-BIND 9.11.1 is a maintenance release, and addresses the security flaws
-disclosed in CVE-2017-3140 and CVE-2017-3141. It also addresses several
-bugs related to the use of an LMDB database to store data related to zones
-added via rndc addzone or catalog zones.
+BIND 9.11.2 is a maintenance release, and addresses the security flaws
+disclosed in CVE-2017-3140, CVE-2017-3141, CVE-2017-3142 and
+CVE-2017-3143. It also addresses several bugs related to the use of an
+LMDB database to store data related to zones added via rndc addzone or
+catalog zones.
 
 Building BIND
 

diff --git a/README.md b/README.md
index 9844570cce087ea593324033294a4e96d27e435d..5a27f0eda97fe9c5c711f1b15a373a35c425a5f3 100644 (file)
--- a/README.md
+++ b/README.md
@@ -236,10 +236,10 @@ CVE-2017-3136, CVE-2017-3137 and CVE-2017-3138.
 
 #### BIND 9.11.2
 
-BIND 9.11.1 is a maintenance release, and addresses the security flaws
-disclosed in CVE-2017-3140 and CVE-2017-3141. It also addresses several
-bugs related to the use of an LMDB database to store data related to
-zones added via `rndc addzone` or catalog zones.
+BIND 9.11.2 is a maintenance release, and addresses the security flaws
+disclosed in CVE-2017-3140, CVE-2017-3141, CVE-2017-3142 and CVE-2017-3143.
+It also addresses several bugs related to the use of an LMDB database to
+store data related to zones added via `rndc addzone` or catalog zones.
 
 ### <a name="build"/> Building BIND
 

diff --git a/doc/arm/notes.xml b/doc/arm/notes.xml
index 37cee0f8696fc9b8c98ae2516c83b9bba8d9c19b..ff53d6568587db0c1a9885e8b4fb9924184061f8 100644 (file)
--- a/doc/arm/notes.xml
+++ b/doc/arm/notes.xml
@@ -93,6 +93,13 @@
 
   <section xml:id="relnotes_security"><info><title>Security Fixes</title></info>
     <itemizedlist>
+      <listitem>
+       <para>
+         An error in TSIG handling could permit unauthorized zone
+         transfers or zone updates. These flaws are disclosed in
+         CVE-2017-3142 and CVE-2017-3143. [RT #45383]
+       </para>
+      </listitem>
       <listitem>
        <para>
          The BIND installer on Windows used an unquoted service path,

diff --git a/lib/dns/dnssec.c b/lib/dns/dnssec.c
index e619366b87a012fb98012029e598f1c8269cf380..2f3d23b5d2cc32ec2d4d1f563f093878754d264a 100644 (file)
--- a/lib/dns/dnssec.c
+++ b/lib/dns/dnssec.c
@@ -1070,6 +1070,8 @@ dns_dnssec_verifymessage(isc_buffer_t *source, dns_message_t *msg,
        mctx = msg->mctx;
 
        msg->verify_attempted = 1;
+       msg->verified_sig = 0;
+       msg->sig0status = dns_tsigerror_badsig;
 
        if (is_response(msg)) {
                if (msg->query.base == NULL)
@@ -1165,6 +1167,7 @@ dns_dnssec_verifymessage(isc_buffer_t *source, dns_message_t *msg,
        }
 
        msg->verified_sig = 1;
+       msg->sig0status = dns_rcode_noerror;
 
        dst_context_destroy(&ctx);
        dns_rdata_freestruct(&sig);

diff --git a/lib/dns/message.c b/lib/dns/message.c
index a2780ed900a3afd64be1b65a122f041a8b5830e3..b97e9011f8f199b24e686c3c95743157738c98f0 100644 (file)
--- a/lib/dns/message.c
+++ b/lib/dns/message.c
@@ -3062,12 +3062,19 @@ dns_message_signer(dns_message_t *msg, dns_name_t *signer) {
 
                result = dns_rdata_tostruct(&rdata, &tsig, NULL);
                INSIST(result == ISC_R_SUCCESS);
-               if (msg->tsigstatus != dns_rcode_noerror)
+               if (msg->verified_sig &&
+                   msg->tsigstatus == dns_rcode_noerror &&
+                   tsig.error == dns_rcode_noerror)
+               {
+                       result = ISC_R_SUCCESS;
+               } else if ((!msg->verified_sig) ||
+                          (msg->tsigstatus != dns_rcode_noerror))
+               {
                        result = DNS_R_TSIGVERIFYFAILURE;
-               else if (tsig.error != dns_rcode_noerror)
+               } else {
+                       INSIST(tsig.error != dns_rcode_noerror);
                        result = DNS_R_TSIGERRORSET;
-               else
-                       result = ISC_R_SUCCESS;
+               }
                dns_rdata_freestruct(&tsig);
 
                if (msg->tsigkey == NULL) {

diff --git a/lib/dns/tsig.c b/lib/dns/tsig.c
index 80550136f76aae7a7acffa162b47c5b26d9dc15b..dd4ce1ec3b56a0844373afe75a277856ed3063c1 100644 (file)
--- a/lib/dns/tsig.c
+++ b/lib/dns/tsig.c
@@ -970,9 +970,10 @@ dns_tsig_sign(dns_message_t *msg) {
                        return (ret);
 
                /*
-                * If this is a response, digest the query signature.
+                * If this is a response and the query's signature
+                * validated, digest the query signature.
                 */
-               if (response) {
+               if (response && (tsig.error == dns_rcode_noerror)) {
                        dns_rdata_t querytsigrdata = DNS_RDATA_INIT;
 
                        ret = dns_rdataset_first(msg->querytsig);
@@ -1209,6 +1210,8 @@ dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
        REQUIRE(tsigkey == NULL || VALID_TSIG_KEY(tsigkey));
 
        msg->verify_attempted = 1;
+       msg->verified_sig = 0;
+       msg->tsigstatus = dns_tsigerror_badsig;
 
        if (msg->tcp_continuation) {
                if (tsigkey == NULL || msg->querytsig == NULL)
@@ -1332,27 +1335,31 @@ dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
 #endif
            alg == DST_ALG_HMACSHA1 ||
            alg == DST_ALG_HMACSHA224 || alg == DST_ALG_HMACSHA256 ||
-           alg == DST_ALG_HMACSHA384 || alg == DST_ALG_HMACSHA512) {
+           alg == DST_ALG_HMACSHA384 || alg == DST_ALG_HMACSHA512)
+       {
                isc_uint16_t digestbits = dst_key_getbits(key);
                if (tsig.siglen > siglen) {
                        tsig_log(msg->tsigkey, 2, "signature length too big");
                        return (DNS_R_FORMERR);
                }
                if (tsig.siglen > 0 &&
-                   (tsig.siglen < 10 || tsig.siglen < ((siglen + 1) / 2))) {
+                   (tsig.siglen < 10 || tsig.siglen < ((siglen + 1) / 2)))
+               {
                        tsig_log(msg->tsigkey, 2,
                                 "signature length below minimum");
                        return (DNS_R_FORMERR);
                }
                if (tsig.siglen > 0 && digestbits != 0 &&
-                   tsig.siglen < ((digestbits + 1) / 8)) {
+                   tsig.siglen < ((digestbits + 1) / 8))
+               {
                        msg->tsigstatus = dns_tsigerror_badtrunc;
                        tsig_log(msg->tsigkey, 2,
                                 "truncated signature length too small");
                        return (DNS_R_TSIGVERIFYFAILURE);
                }
                if (tsig.siglen > 0 && digestbits == 0 &&
-                   tsig.siglen < siglen) {
+                   tsig.siglen < siglen)
+               {
                        msg->tsigstatus = dns_tsigerror_badtrunc;
                        tsig_log(msg->tsigkey, 2, "signature length too small");
                        return (DNS_R_TSIGVERIFYFAILURE);
@@ -1371,7 +1378,7 @@ dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
                if (ret != ISC_R_SUCCESS)
                        return (ret);
 
-               if (response) {
+               if (response && (tsig.error == dns_rcode_noerror)) {
                        isc_buffer_init(&databuf, data, sizeof(data));
                        isc_buffer_putuint16(&databuf, querytsig.siglen);
                        isc_buffer_usedregion(&databuf, &r);
@@ -1476,10 +1483,9 @@ dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
                        tsig_log(msg->tsigkey, 2,
                                 "signature failed to verify(1)");
                        goto cleanup_context;
-               } else if (ret != ISC_R_SUCCESS)
+               } else if (ret != ISC_R_SUCCESS) {
                        goto cleanup_context;
-
-               dst_context_destroy(&ctx);
+               }
        } else if (tsig.error != dns_tsigerror_badsig &&
                   tsig.error != dns_tsigerror_badkey) {
                msg->tsigstatus = dns_tsigerror_badsig;
@@ -1487,18 +1493,18 @@ dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
                return (DNS_R_TSIGVERIFYFAILURE);
        }
 
-       msg->tsigstatus = dns_rcode_noerror;
-
        if (tsig.error != dns_rcode_noerror) {
+               msg->tsigstatus = tsig.error;
                if (tsig.error == dns_tsigerror_badtime)
-                       return (DNS_R_CLOCKSKEW);
+                       ret = DNS_R_CLOCKSKEW;
                else
-                       return (DNS_R_TSIGERRORSET);
+                       ret = DNS_R_TSIGERRORSET;
+               goto cleanup_context;
        }
 
+       msg->tsigstatus = dns_rcode_noerror;
        msg->verified_sig = 1;
-
-       return (ISC_R_SUCCESS);
+       ret = ISC_R_SUCCESS;
 
 cleanup_context:
        if (ctx != NULL)
@@ -1530,6 +1536,9 @@ tsig_verify_tcp(isc_buffer_t *source, dns_message_t *msg) {
        REQUIRE(msg->tcp_continuation == 1);
        REQUIRE(msg->querytsig != NULL);
 
+       msg->verified_sig = 0;
+       msg->tsigstatus = dns_tsigerror_badsig;
+
        if (!is_response(msg))
                return (DNS_R_EXPECTEDRESPONSE);
 
@@ -1568,7 +1577,8 @@ tsig_verify_tcp(isc_buffer_t *source, dns_message_t *msg) {
                 * Do the key name and algorithm match that of the query?
                 */
                if (!dns_name_equal(keyname, &tsigkey->name) ||
-                   !dns_name_equal(&tsig.algorithm, &querytsig.algorithm)) {
+                   !dns_name_equal(&tsig.algorithm, &querytsig.algorithm))
+               {
                        msg->tsigstatus = dns_tsigerror_badkey;
                        ret = DNS_R_TSIGVERIFYFAILURE;
                        tsig_log(msg->tsigkey, 2,
@@ -1587,7 +1597,8 @@ tsig_verify_tcp(isc_buffer_t *source, dns_message_t *msg) {
                        ret = DNS_R_CLOCKSKEW;
                        goto cleanup_querystruct;
                } else if (now + msg->timeadjust <
-                          tsig.timesigned - tsig.fudge) {
+                          tsig.timesigned - tsig.fudge)
+               {
                        msg->tsigstatus = dns_tsigerror_badtime;
                        tsig_log(msg->tsigkey, 2,
                                 "signature is in the future");
@@ -1693,10 +1704,12 @@ tsig_verify_tcp(isc_buffer_t *source, dns_message_t *msg) {
                sig_r.length = tsig.siglen;
                if (tsig.siglen == 0) {
                        if (tsig.error != dns_rcode_noerror) {
-                               if (tsig.error == dns_tsigerror_badtime)
+                               msg->tsigstatus = tsig.error;
+                               if (tsig.error == dns_tsigerror_badtime) {
                                        ret = DNS_R_CLOCKSKEW;
-                               else
+                               } else {
                                        ret = DNS_R_TSIGERRORSET;
+                               }
                        } else {
                                tsig_log(msg->tsigkey, 2,
                                         "signature is empty");
@@ -1712,24 +1725,32 @@ tsig_verify_tcp(isc_buffer_t *source, dns_message_t *msg) {
                                 "signature failed to verify(2)");
                        ret = DNS_R_TSIGVERIFYFAILURE;
                        goto cleanup_context;
-               }
-               else if (ret != ISC_R_SUCCESS)
+               } else if (ret != ISC_R_SUCCESS) {
                        goto cleanup_context;
+               }
 
-               dst_context_destroy(&msg->tsigctx);
+               if (tsig.error != dns_rcode_noerror) {
+                       msg->tsigstatus = tsig.error;
+                       if (tsig.error == dns_tsigerror_badtime)
+                               ret = DNS_R_CLOCKSKEW;
+                       else
+                               ret = DNS_R_TSIGERRORSET;
+                       goto cleanup_context;
+               }
        }
 
        msg->tsigstatus = dns_rcode_noerror;
-       return (ISC_R_SUCCESS);
+       msg->verified_sig = 1;
+       ret = ISC_R_SUCCESS;
 
  cleanup_context:
-       dst_context_destroy(&msg->tsigctx);
+       if (msg->tsigctx != NULL)
+               dst_context_destroy(&msg->tsigctx);
 
  cleanup_querystruct:
        dns_rdata_freestruct(&querytsig);
 
        return (ret);
-
 }
 
 isc_result_t