From 93aec4d3d80a0d1cdb6553f70f35a2e2cb1fbaa8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20Men=C5=A1=C3=ADk?= <pemensik@redhat.com>
Date: Tue, 11 Apr 2017 16:19:51 +0200
Subject: [PATCH 2/3] 4578. [security] Some chaining (CNAME or DNAME)
responses to upstream queries could trigger assertion
failures. (CVE-2017-3137) [RT #44734]
(including part of commit fea8a9d)
---
bin/tests/system/dname/ans3/ans.pl | 16 +-
bin/tests/system/dname/ns1/root.db | 2 +-
bin/tests/system/dname/ns2/example.db | 3 +-
bin/tests/system/dname/tests.sh | 17 +-
lib/dns/name.c | 2 -
lib/dns/resolver.c | 850 +++++++++++++---------------------
6 files changed, 349 insertions(+), 541 deletions(-)
diff --git a/bin/tests/system/dname/ans3/ans.pl b/bin/tests/system/dname/ans3/ans.pl
index 271fc7d..af338fe 100644
--- a/bin/tests/system/dname/ans3/ans.pl
+++ b/bin/tests/system/dname/ans3/ans.pl
@@ -1,10 +1,18 @@
#!/usr/bin/env perl
#
-# Copyright (C) 2014-2016 Internet Systems Consortium, Inc. ("ISC")
+# Copyright (C) 2017 Internet Systems Consortium, Inc. ("ISC")
#
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+# AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+# OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+# PERFORMANCE OF THIS SOFTWARE.
use strict;
use warnings;
diff --git a/bin/tests/system/dname/ns1/root.db b/bin/tests/system/dname/ns1/root.db
index 2e84ae0..3d55ace 100644
--- a/bin/tests/system/dname/ns1/root.db
+++ b/bin/tests/system/dname/ns1/root.db
@@ -1,4 +1,4 @@
-; Copyright (C) 2011 Internet Systems Consortium, Inc. ("ISC")
+; Copyright (C) 2011, 2017 Internet Systems Consortium, Inc. ("ISC")
;
; Permission to use, copy, modify, and/or distribute this software for any
; purpose with or without fee is hereby granted, provided that the above
diff --git a/bin/tests/system/dname/ns2/example.db b/bin/tests/system/dname/ns2/example.db
index 4289134..c0193de 100644
--- a/bin/tests/system/dname/ns2/example.db
+++ b/bin/tests/system/dname/ns2/example.db
@@ -1,4 +1,4 @@
-; Copyright (C) 2011 Internet Systems Consortium, Inc. ("ISC")
+; Copyright (C) 2011, 2017 Internet Systems Consortium, Inc. ("ISC")
;
; Permission to use, copy, modify, and/or distribute this software for any
; purpose with or without fee is hereby granted, provided that the above
@@ -29,6 +29,7 @@ a.short A 10.0.0.1
short-dname DNAME short
a.longlonglonglonglonglonglonglonglonglonglonglonglong A 10.0.0.2
long-dname DNAME longlonglonglonglonglonglonglonglonglonglonglonglong
+toolong-dname DNAME longlonglonglonglonglonglonglonglonglonglonglonglong
cname CNAME a.cnamedname
cnamedname DNAME target
a.target A 10.0.0.3
diff --git a/bin/tests/system/dname/tests.sh b/bin/tests/system/dname/tests.sh
index 6dc9e88..1487bd9 100644
--- a/bin/tests/system/dname/tests.sh
+++ b/bin/tests/system/dname/tests.sh
@@ -1,6 +1,6 @@
#!/bin/sh
#
-# Copyright (C) 2011, 2012 Internet Systems Consortium, Inc. ("ISC")
+# Copyright (C) 2011, 2012, 2017 Internet Systems Consortium, Inc. ("ISC")
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
@@ -57,10 +57,19 @@ grep "status: YXDOMAIN" dig.out.ns2.toolong > /dev/null || ret=1
if [ $ret != 0 ]; then echo "I:failed"; fi
status=`expr $status + $ret`
-echo "I:checking (too) long dname from recursive"
+echo "I:checking (too) long dname from recursive with cached DNAME"
ret=0
-$DIG 01234567890123456789012345678901234567890123456789.longlonglonglonglonglonglonglonglonglonglonglonglonglonglong.longlonglonglonglonglonglonglonglonglonglonglonglonglonglong.longlonglonglonglonglonglonglonglonglonglonglonglonglonglong.long-dname.example @10.53.0.4 a -p 5300 > dig.out.ns4.toolong || ret=1
-grep "status: YXDOMAIN" dig.out.ns4.toolong > /dev/null || ret=1
+$DIG 01234567890123456789012345678901234567890123456789.longlonglonglonglonglonglonglonglonglonglonglonglonglonglong.longlonglonglonglonglonglonglonglonglonglonglonglonglonglong.longlonglonglonglonglonglonglonglonglonglonglonglonglonglong.long-dname.example @10.53.0.4 a -p 5300 > dig.out.ns4.cachedtoolong || ret=1
+grep "status: YXDOMAIN" dig.out.ns4.cachedtoolong > /dev/null || ret=1
+grep '^long-dname\.example\..*DNAME.*long' dig.out.ns4.cachedtoolong > /dev/null || ret=1
+if [ $ret != 0 ]; then echo "I:failed"; fi
+status=`expr $status + $ret`
+
+echo "I:checking (too) long dname from recursive without cached DNAME"
+ret=0
+$DIG 01234567890123456789012345678901234567890123456789.longlonglonglonglonglonglonglonglonglonglonglonglonglonglong.longlonglonglonglonglonglonglonglonglonglonglonglonglonglong.longlonglonglonglonglonglonglonglonglonglonglonglonglong.toolong-dname.example @10.53.0.4 a -p 5300 > dig.out.ns4.uncachedtoolong || ret=1
+grep "status: YXDOMAIN" dig.out.ns4.uncachedtoolong > /dev/null || ret=1
+grep '^toolong-dname\.example\..*DNAME.*long' dig.out.ns4.uncachedtoolong > /dev/null || ret=1
if [ $ret != 0 ]; then echo "I:failed"; fi
status=`expr $status + $ret`
diff --git a/lib/dns/name.c b/lib/dns/name.c
index 93173ee..d02e713 100644
--- a/lib/dns/name.c
+++ b/lib/dns/name.c
@@ -2119,11 +2119,9 @@ dns_name_split(dns_name_t *name, unsigned int suffixlabels,
REQUIRE(prefix != NULL || suffix != NULL);
REQUIRE(prefix == NULL ||
(VALID_NAME(prefix) &&
- prefix->buffer != NULL &&
BINDABLE(prefix)));
REQUIRE(suffix == NULL ||
(VALID_NAME(suffix) &&
- suffix->buffer != NULL &&
BINDABLE(suffix)));
splitlabel = name->labels - suffixlabels;
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index c3607fa..860a792 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -3817,6 +3817,7 @@ is_lame(fetchctx_t *fctx) {
isc_result_t result;
if (message->rcode != dns_rcode_noerror &&
+ message->rcode != dns_rcode_yxdomain &&
message->rcode != dns_rcode_nxdomain)
return (ISC_FALSE);
@@ -5386,79 +5387,6 @@ chase_additional(fetchctx_t *fctx) {
goto again;
}
-static inline isc_result_t
-cname_target(dns_rdataset_t *rdataset, dns_name_t *tname) {
- isc_result_t result;
- dns_rdata_t rdata = DNS_RDATA_INIT;
- dns_rdata_cname_t cname;
-
- result = dns_rdataset_first(rdataset);
- if (result != ISC_R_SUCCESS)
- return (result);
- dns_rdataset_current(rdataset, &rdata);
- result = dns_rdata_tostruct(&rdata, &cname, NULL);
- if (result != ISC_R_SUCCESS)
- return (result);
- dns_name_init(tname, NULL);
- dns_name_clone(&cname.cname, tname);
- dns_rdata_freestruct(&cname);
-
- return (ISC_R_SUCCESS);
-}
-
-/*%
- * Construct the synthesised CNAME from the existing QNAME and
- * the DNAME RR and store it in 'target'.
- */
-static inline isc_result_t
-dname_target(dns_rdataset_t *rdataset, dns_name_t *qname,
- unsigned int nlabels, dns_name_t *target)
-{
- isc_result_t result;
- dns_rdata_t rdata = DNS_RDATA_INIT;
- dns_rdata_dname_t dname;
- dns_fixedname_t prefix;
-
- /*
- * Get the target name of the DNAME.
- */
- result = dns_rdataset_first(rdataset);
- if (result != ISC_R_SUCCESS)
- return (result);
- dns_rdataset_current(rdataset, &rdata);
- result = dns_rdata_tostruct(&rdata, &dname, NULL);
- if (result != ISC_R_SUCCESS)
- return (result);
-
- dns_fixedname_init(&prefix);
- dns_name_split(qname, nlabels, dns_fixedname_name(&prefix), NULL);
- result = dns_name_concatenate(dns_fixedname_name(&prefix),
- &dname.dname, target, NULL);
- dns_rdata_freestruct(&dname);
- return (result);
-}
-
-/*%
- * Check if it was possible to construct 'qname' from 'lastcname'
- * and 'rdataset'.
- */
-static inline isc_result_t
-fromdname(dns_rdataset_t *rdataset, dns_name_t *lastcname,
- unsigned int nlabels, const dns_name_t *qname)
-{
- dns_fixedname_t fixed;
- isc_result_t result;
- dns_name_t *target;
-
- dns_fixedname_init(&fixed);
- target = dns_fixedname_name(&fixed);
- result = dname_target(rdataset, lastcname, nlabels, target);
- if (result != ISC_R_SUCCESS || !dns_name_equal(qname, target))
- return (ISC_R_NOTFOUND);
-
- return (ISC_R_SUCCESS);
-}
-
static isc_boolean_t
is_answeraddress_allowed(dns_view_t *view, dns_name_t *name,
dns_rdataset_t *rdataset)
@@ -5534,9 +5462,8 @@ is_answeraddress_allowed(dns_view_t *view, dns_name_t *name,
}
static isc_boolean_t
-is_answertarget_allowed(dns_view_t *view, dns_name_t *name,
- dns_rdatatype_t type, dns_name_t *tname,
- dns_name_t *domain)
+is_answertarget_allowed(fetchctx_t *fctx, dns_name_t *qname, dns_name_t *rname,
+ dns_rdataset_t *rdataset, isc_boolean_t *chainingp)
{
isc_result_t result;
dns_rbtnode_t *node = NULL;
@@ -5544,8 +5471,57 @@ is_answertarget_allowed(dns_view_t *view, dns_name_t *name,
char tnamebuf[DNS_NAME_FORMATSIZE];
char classbuf[64];
char typebuf[64];
+ dns_name_t *tname = NULL;
+ dns_rdata_cname_t cname;
+ dns_rdata_dname_t dname;
+ dns_view_t *view = fctx->res->view;
+ dns_rdata_t rdata = DNS_RDATA_INIT;
+ unsigned int nlabels;
+ dns_fixedname_t fixed;
+ dns_name_t prefix;
+
+ REQUIRE(rdataset != NULL);
+ REQUIRE(rdataset->type == dns_rdatatype_cname ||
+ rdataset->type == dns_rdatatype_dname);
+
+ /*
+ * By default, we allow any target name.
+ * If newqname != NULL we also need to extract the newqname.
+ */
+ if (chainingp == NULL && view->denyanswernames == NULL)
+ return (ISC_TRUE);
+
+ result = dns_rdataset_first(rdataset);
+ RUNTIME_CHECK(result == ISC_R_SUCCESS);
+ dns_rdataset_current(rdataset, &rdata);
+ switch (rdataset->type) {
+ case dns_rdatatype_cname:
+ result = dns_rdata_tostruct(&rdata, &cname, NULL);
+ RUNTIME_CHECK(result == ISC_R_SUCCESS);
+ tname = &cname.cname;
+ break;
+ case dns_rdatatype_dname:
+ result = dns_rdata_tostruct(&rdata, &dname, NULL);
+ RUNTIME_CHECK(result == ISC_R_SUCCESS);
+ dns_name_init(&prefix, NULL);
+ dns_fixedname_init(&fixed);
+ tname = dns_fixedname_name(&fixed);
+ nlabels = dns_name_countlabels(qname) -
+ dns_name_countlabels(rname);
+ dns_name_split(qname, nlabels, &prefix, NULL);
+ result = dns_name_concatenate(&prefix, &dname.dname, tname,
+ NULL);
+ if (result == DNS_R_NAMETOOLONG)
+ return (ISC_TRUE);
+ RUNTIME_CHECK(result == ISC_R_SUCCESS);
+ break;
+ default:
+ INSIST(0);
+ }
+
+ if (chainingp != NULL)
+ *chainingp = ISC_TRUE;
- /* By default, we allow any target name. */
if (view->denyanswernames == NULL)
return (ISC_TRUE);
@@ -5554,8 +5530,8 @@ is_answertarget_allowed(dns_view_t *view, dns_name_t *name,
* or partially, allow it.
*/
if (view->answernames_exclude != NULL) {
- result = dns_rbt_findnode(view->answernames_exclude, name, NULL,
- &node, NULL, 0, NULL, NULL);
+ result = dns_rbt_findnode(view->answernames_exclude, qname,
+ NULL, &node, NULL, 0, NULL, NULL);
if (result == ISC_R_SUCCESS || result == DNS_R_PARTIALMATCH)
return (ISC_TRUE);
}
@@ -5563,7 +5539,7 @@ is_answertarget_allowed(dns_view_t *view, dns_name_t *name,
/*
* If the target name is a subdomain of the search domain, allow it.
*/
- if (dns_name_issubdomain(tname, domain))
+ if (dns_name_issubdomain(tname, &fctx->domain))
return (ISC_TRUE);
/*
@@ -5572,9 +5548,9 @@ is_answertarget_allowed(dns_view_t *view, dns_name_t *name,
result = dns_rbt_findnode(view->denyanswernames, tname, NULL, &node,
NULL, 0, NULL, NULL);
if (result == ISC_R_SUCCESS || result == DNS_R_PARTIALMATCH) {
- dns_name_format(name, qnamebuf, sizeof(qnamebuf));
+ dns_name_format(qname, qnamebuf, sizeof(qnamebuf));
dns_name_format(tname, tnamebuf, sizeof(tnamebuf));
- dns_rdatatype_format(type, typebuf, sizeof(typebuf));
+ dns_rdatatype_format(rdataset->type, typebuf, sizeof(typebuf));
dns_rdataclass_format(view->rdclass, classbuf,
sizeof(classbuf));
isc_log_write(dns_lctx, DNS_LOGCATEGORY_RESOLVER,
@@ -6057,473 +6033,301 @@ noanswer_response(fetchctx_t *fctx, dns_name_t *oqname,
return (ISC_R_SUCCESS);
}
+static isc_boolean_t
+validinanswer(dns_rdataset_t *rdataset, fetchctx_t *fctx) {
+ if (rdataset->type == dns_rdatatype_nsec3) {
+ /*
+ * NSEC3 records are not allowed to
+ * appear in the answer section.
+ */
+ log_formerr(fctx, "NSEC3 in answer");
+ return (ISC_FALSE);
+ }
+ if (rdataset->type == dns_rdatatype_tkey) {
+ /*
+ * TKEY is not a valid record in a
+ * response to any query we can make.
+ */
+ log_formerr(fctx, "TKEY in answer");
+ return (ISC_FALSE);
+ }
+ if (rdataset->rdclass != fctx->res->rdclass) {
+ log_formerr(fctx, "Mismatched class in answer");
+ return (ISC_FALSE);
+ }
+ return (ISC_TRUE);
+}
+
static isc_result_t
answer_response(fetchctx_t *fctx) {
isc_result_t result;
- dns_message_t *message;
- dns_name_t *name, *dname = NULL, *qname, tname, *ns_name;
- dns_name_t *cname = NULL, *lastcname = NULL;
- dns_rdataset_t *rdataset, *ns_rdataset;
- isc_boolean_t done, external, aa, found, want_chaining;
- isc_boolean_t have_answer, found_cname, found_dname, found_type;
- isc_boolean_t wanted_chaining;
- unsigned int aflag, chaining;
+ dns_message_t *message = NULL;
+ dns_name_t *name = NULL, *qname = NULL, *ns_name = NULL;
+ dns_name_t *aname = NULL, *cname = NULL, *dname = NULL;
+ dns_rdataset_t *rdataset = NULL, *sigrdataset = NULL;
+ dns_rdataset_t *ardataset = NULL, *crdataset = NULL;
+ dns_rdataset_t *drdataset = NULL, *ns_rdataset = NULL;
+ isc_boolean_t done = ISC_FALSE, aa;
+ unsigned int dname_labels, domain_labels;
+ isc_boolean_t chaining = ISC_FALSE;
dns_rdatatype_t type;
- dns_fixedname_t fdname, fqname;
- dns_view_t *view;
+ dns_view_t *view = NULL;
+ dns_trust_t trust;
+
+ REQUIRE(VALID_FCTX(fctx));
FCTXTRACE("answer_response");
message = fctx->rmessage;
+ qname = &fctx->name;
+ view = fctx->res->view;
+ type = fctx->type;
/*
- * Examine the answer section, marking those rdatasets which are
- * part of the answer and should be cached.
+ * There can be multiple RRSIG and SIG records at a name so
+ * we treat these types as a subset of ANY.
*/
+ if (type == dns_rdatatype_rrsig || type == dns_rdatatype_sig) {
+ type = dns_rdatatype_any;
+ }
- done = ISC_FALSE;
- found_cname = ISC_FALSE;
- found_dname = ISC_FALSE;
- found_type = ISC_FALSE;
- have_answer = ISC_FALSE;
- want_chaining = ISC_FALSE;
- chaining = 0;
- POST(want_chaining);
- if ((message->flags & DNS_MESSAGEFLAG_AA) != 0)
- aa = ISC_TRUE;
- else
- aa = ISC_FALSE;
- qname = &fctx->name;
- type = fctx->type;
- view = fctx->res->view;
- result = dns_message_firstname(message, DNS_SECTION_ANSWER);
- while (!done && result == ISC_R_SUCCESS) {
- dns_namereln_t namereln, lastreln;
- int order, lastorder;
- unsigned int nlabels, lastnlabels;
+ /*
+ * Bigger than any valid DNAME label count.
+ */
+ dname_labels = dns_name_countlabels(qname);
+ domain_labels = dns_name_countlabels(&fctx->domain);
+
+ /*
+ * Perform a single pass looking for the answer, cname or covering
+ * dname.
+ */
+ for (result = dns_message_firstname(message, DNS_SECTION_ANSWER);
+ result == ISC_R_SUCCESS;
+ result = dns_message_nextname(message, DNS_SECTION_ANSWER))
+ {
+ int order;
+ unsigned int nlabels;
+ dns_namereln_t namereln;
name = NULL;
dns_message_currentname(message, DNS_SECTION_ANSWER, &name);
- external = ISC_TF(!dns_name_issubdomain(name, &fctx->domain));
namereln = dns_name_fullcompare(qname, name, &order, &nlabels);
-
- if (namereln == dns_namereln_equal) {
- wanted_chaining = ISC_FALSE;
+ switch (namereln) {
+ case dns_namereln_equal:
for (rdataset = ISC_LIST_HEAD(name->list);
rdataset != NULL;
- rdataset = ISC_LIST_NEXT(rdataset, link)) {
- found = ISC_FALSE;
- want_chaining = ISC_FALSE;
- aflag = 0;
- if (rdataset->type == dns_rdatatype_nsec3) {
- /*
- * NSEC3 records are not allowed to
- * appear in the answer section.
- */
- log_formerr(fctx, "NSEC3 in answer");
- return (DNS_R_FORMERR);
- }
- if (rdataset->type == dns_rdatatype_tkey) {
- /*
- * TKEY is not a valid record in a
- * response to any query we can make.
- */
- log_formerr(fctx, "TKEY in answer");
- return (DNS_R_FORMERR);
- }
- if (rdataset->rdclass != fctx->res->rdclass) {
- log_formerr(fctx, "Mismatched class "
- "in answer");
- return (DNS_R_FORMERR);
- }
-
- /*
- * Apply filters, if given, on answers to reject
- * a malicious attempt of rebinding.
- */
- if ((rdataset->type == dns_rdatatype_a ||
- rdataset->type == dns_rdatatype_aaaa) &&
- !is_answeraddress_allowed(view, name,
- rdataset)) {
- return (DNS_R_SERVFAIL);
- }
-
- if (rdataset->type == type && !found_cname) {
- /*
- * We've found an ordinary answer.
- */
- found = ISC_TRUE;
- found_type = ISC_TRUE;
- done = ISC_TRUE;
- aflag = DNS_RDATASETATTR_ANSWER;
- } else if (type == dns_rdatatype_any) {
- /*
- * We've found an answer matching
- * an ANY query. There may be
- * more.
- */
- found = ISC_TRUE;
- aflag = DNS_RDATASETATTR_ANSWER;
- } else if (rdataset->type == dns_rdatatype_rrsig
- && rdataset->covers == type
- && !found_cname) {
- /*
- * We've found a signature that
- * covers the type we're looking for.
- */
- found = ISC_TRUE;
- found_type = ISC_TRUE;
- aflag = DNS_RDATASETATTR_ANSWERSIG;
- } else if (rdataset->type ==
- dns_rdatatype_cname
- && !found_type) {
- /*
- * We're looking for something else,
- * but we found a CNAME.
- *
- * Getting a CNAME response for some
- * query types is an error, see
- * RFC 4035, Section 2.5.
- */
- if (type == dns_rdatatype_rrsig ||
- type == dns_rdatatype_key ||
- type == dns_rdatatype_nsec) {
- char buf[DNS_RDATATYPE_FORMATSIZE];
- dns_rdatatype_format(fctx->type,
- buf, sizeof(buf));
- log_formerr(fctx,
- "CNAME response "
- "for %s RR", buf);
- return (DNS_R_FORMERR);
- }
- found = ISC_TRUE;
- found_cname = ISC_TRUE;
- want_chaining = ISC_TRUE;
- aflag = DNS_RDATASETATTR_ANSWER;
- result = cname_target(rdataset,
- &tname);
- if (result != ISC_R_SUCCESS)
- return (result);
- /* Apply filters on the target name. */
- if (!is_answertarget_allowed(view,
- name,
- rdataset->type,
- &tname,
- &fctx->domain)) {
- return (DNS_R_SERVFAIL);
+ rdataset = ISC_LIST_NEXT(rdataset, link))
+ {
+ if (rdataset->type == type ||
+ type == dns_rdatatype_any)
+ {
+ aname = name;
+ if (type != dns_rdatatype_any) {
+ ardataset = rdataset;
}
- lastcname = name;
- } else if (rdataset->type == dns_rdatatype_rrsig
- && rdataset->covers ==
- dns_rdatatype_cname
- && !found_type) {
- /*
- * We're looking for something else,
- * but we found a SIG CNAME.
- */
- found = ISC_TRUE;
- found_cname = ISC_TRUE;
- aflag = DNS_RDATASETATTR_ANSWERSIG;
+ break;
}
-
- if (found) {
- /*
- * We've found an answer to our
- * question.
- */
- name->attributes |=
- DNS_NAMEATTR_CACHE;
- rdataset->attributes |=
- DNS_RDATASETATTR_CACHE;
- rdataset->trust = dns_trust_answer;
- if (chaining == 0) {
- /*
- * This data is "the" answer
- * to our question only if
- * we're not chaining (i.e.
- * if we haven't followed
- * a CNAME or DNAME).
- */
- INSIST(!external);
- /*
- * Don't use found_cname here
- * as we have just set it
- * above.
- */
- if (cname == NULL &&
- !found_dname &&
- aflag ==
- DNS_RDATASETATTR_ANSWER)
- {
- have_answer = ISC_TRUE;
- if (found_cname &&
- cname == NULL)
- cname = name;
- name->attributes |=
- DNS_NAMEATTR_ANSWER;
- }
- rdataset->attributes |= aflag;
- if (aa)
- rdataset->trust =
- dns_trust_authanswer;
- } else if (external) {
- /*
- * This data is outside of
- * our query domain, and
- * may not be cached.
- */
- rdataset->attributes |=
- DNS_RDATASETATTR_EXTERNAL;
- }
-
- /*
- * Mark any additional data related
- * to this rdataset.
- */
- (void)dns_rdataset_additionaldata(
- rdataset,
- check_related,
- fctx);
-
- /*
- * CNAME chaining.
- */
- if (want_chaining) {
- wanted_chaining = ISC_TRUE;
- name->attributes |=
- DNS_NAMEATTR_CHAINING;
- rdataset->attributes |=
- DNS_RDATASETATTR_CHAINING;
- qname = &tname;
- }
+ if (rdataset->type == dns_rdatatype_cname) {
+ cname = name;
+ crdataset = rdataset;
+ break;
}
- /*
- * We could add an "else" clause here and
- * log that we're ignoring this rdataset.
- */
}
+ break;
+
+ case dns_namereln_subdomain:
/*
- * If wanted_chaining is true, we've done
- * some chaining as the result of processing
- * this node, and thus we need to set
- * chaining to true.
- *
- * We don't set chaining inside of the
- * rdataset loop because doing that would
- * cause us to ignore the signatures of
- * CNAMEs.
+ * In-scope DNAME records must have at least
+ * as many labels as the domain being queried.
+ * They also must be less that qname's labels
+ * and any previously found dname.
*/
- if (wanted_chaining && chaining < 2U)
- chaining++;
- } else {
- dns_rdataset_t *dnameset = NULL;
- isc_boolean_t synthcname = ISC_FALSE;
-
- if (lastcname != NULL) {
- lastreln = dns_name_fullcompare(lastcname,
- name,
- &lastorder,
- &lastnlabels);
- if (lastreln == dns_namereln_subdomain &&
- lastnlabels == dns_name_countlabels(name))
- synthcname = ISC_TRUE;
+ if (nlabels >= dname_labels || nlabels < domain_labels)
+ {
+ continue;
}
/*
- * Look for a DNAME (or its SIG). Anything else is
- * ignored.
+ * We are looking for the shortest DNAME if there
+ * are multiple ones (which there shouldn't be).
*/
- wanted_chaining = ISC_FALSE;
for (rdataset = ISC_LIST_HEAD(name->list);
rdataset != NULL;
rdataset = ISC_LIST_NEXT(rdataset, link))
{
- if (rdataset->rdclass != fctx->res->rdclass) {
- log_formerr(fctx, "Mismatched class "
- "in answer");
- return (DNS_R_FORMERR);
- }
-
- /*
- * Only pass DNAME or RRSIG(DNAME).
- */
- if (rdataset->type != dns_rdatatype_dname &&
- (rdataset->type != dns_rdatatype_rrsig ||
- rdataset->covers != dns_rdatatype_dname))
+ if (rdataset->type != dns_rdatatype_dname) {
continue;
-
- /*
- * If we're not chaining, then the DNAME and
- * its signature should not be external.
- */
- if (chaining == 0 && external) {
- char qbuf[DNS_NAME_FORMATSIZE];
- char obuf[DNS_NAME_FORMATSIZE];
-
- dns_name_format(name, qbuf,
- sizeof(qbuf));
- dns_name_format(&fctx->domain, obuf,
- sizeof(obuf));
- log_formerr(fctx, "external DNAME or "
- "RRSIG covering DNAME "
- "in answer: %s is "
- "not in %s", qbuf, obuf);
- return (DNS_R_FORMERR);
- }
-
- /*
- * If DNAME + synthetic CNAME then the
- * namereln is dns_namereln_subdomain.
- */
- if (namereln != dns_namereln_subdomain &&
- !synthcname)
- {
- char qbuf[DNS_NAME_FORMATSIZE];
- char obuf[DNS_NAME_FORMATSIZE];
-
- dns_name_format(qname, qbuf,
- sizeof(qbuf));
- dns_name_format(name, obuf,
- sizeof(obuf));
- log_formerr(fctx, "unrelated DNAME "
- "in answer: %s is "
- "not in %s", qbuf, obuf);
- return (DNS_R_FORMERR);
}
+ dname = name;
+ drdataset = rdataset;
+ dname_labels = nlabels;
+ break;
+ }
+ break;
+ default:
+ break;
+ }
+ }
- aflag = 0;
- if (rdataset->type == dns_rdatatype_dname) {
- want_chaining = ISC_TRUE;
- POST(want_chaining);
- aflag = DNS_RDATASETATTR_ANSWER;
- dns_fixedname_init(&fdname);
- dname = dns_fixedname_name(&fdname);
- if (synthcname) {
- result = fromdname(rdataset,
- lastcname,
- lastnlabels,
- qname);
- } else {
- result = dname_target(rdataset,
- qname,
- nlabels,
- dname);
- }
- if (result == ISC_R_NOSPACE) {
- /*
- * We can't construct the
- * DNAME target. Do not
- * try to continue.
- */
- want_chaining = ISC_FALSE;
- POST(want_chaining);
- } else if (result != ISC_R_SUCCESS)
- return (result);
- else
- dnameset = rdataset;
+ if (dname != NULL) {
+ aname = NULL;
+ ardataset = NULL;
+ cname = NULL;
+ crdataset = NULL;
+ } else if (aname != NULL) {
+ cname = NULL;
+ crdataset = NULL;
+ }
- if (!synthcname &&
- !is_answertarget_allowed(view,
- qname, rdataset->type,
- dname, &fctx->domain))
- {
- return (DNS_R_SERVFAIL);
- }
- } else {
- /*
- * We've found a signature that
- * covers the DNAME.
- */
- aflag = DNS_RDATASETATTR_ANSWERSIG;
- }
+ aa = ISC_TF((message->flags & DNS_MESSAGEFLAG_AA) != 0);
+ trust = aa ? dns_trust_authanswer : dns_trust_answer;
- /*
- * We've found an answer to our
- * question.
- */
- name->attributes |= DNS_NAMEATTR_CACHE;
- rdataset->attributes |= DNS_RDATASETATTR_CACHE;
- rdataset->trust = dns_trust_answer;
- /*
- * If we are not chaining or the first CNAME
- * is a synthesised CNAME before the DNAME.
- */
- if ((chaining == 0) ||
- (chaining == 1U && synthcname))
- {
- /*
- * This data is "the" answer to
- * our question only if we're
- * not chaining.
- */
- INSIST(!external);
- if (aflag == DNS_RDATASETATTR_ANSWER) {
- have_answer = ISC_TRUE;
- found_dname = ISC_TRUE;
- if (cname != NULL &&
- synthcname)
- {
- cname->attributes &=
- ~DNS_NAMEATTR_ANSWER;
- }
- name->attributes |=
- DNS_NAMEATTR_ANSWER;
- }
- rdataset->attributes |= aflag;
- if (aa)
- rdataset->trust =
- dns_trust_authanswer;
- } else if (external) {
- rdataset->attributes |=
- DNS_RDATASETATTR_EXTERNAL;
- }
+ if (aname != NULL && type == dns_rdatatype_any) {
+ for (rdataset = ISC_LIST_HEAD(aname->list);
+ rdataset != NULL;
+ rdataset = ISC_LIST_NEXT(rdataset, link))
+ {
+ if (!validinanswer(rdataset, fctx)) {
+ return (DNS_R_FORMERR);
}
-
- /*
- * DNAME chaining.
- */
- if (dnameset != NULL) {
- if (!synthcname) {
- /*
- * Copy the dname into the qname fixed
- * name.
- *
- * Although we check for failure of the
- * copy operation, in practice it
- * should never fail since we already
- * know that the result fits in a
- * fixedname.
- */
- dns_fixedname_init(&fqname);
- qname = dns_fixedname_name(&fqname);
- result = dns_name_copy(dname, qname,
- NULL);
- if (result != ISC_R_SUCCESS)
- return (result);
- }
- wanted_chaining = ISC_TRUE;
- name->attributes |= DNS_NAMEATTR_CHAINING;
- dnameset->attributes |=
- DNS_RDATASETATTR_CHAINING;
+ if ((fctx->type == dns_rdatatype_sig ||
+ fctx->type == dns_rdatatype_rrsig) &&
+ rdataset->type != fctx->type)
+ {
+ continue;
}
- /*
- * Ensure that we can't ever get chaining == 1
- * above if we have processed a DNAME.
- */
- if (wanted_chaining && chaining < 2U)
- chaining += 2;
+ if ((rdataset->type == dns_rdatatype_a ||
+ rdataset->type == dns_rdatatype_aaaa) &&
+ !is_answeraddress_allowed(view, aname, rdataset))
+ {
+ return (DNS_R_SERVFAIL);
+ }
+ if ((rdataset->type == dns_rdatatype_cname ||
+ rdataset->type == dns_rdatatype_dname) &&
+ !is_answertarget_allowed(fctx, qname, aname,
+ rdataset, NULL))
+ {
+ return (DNS_R_SERVFAIL);
+ }
+ aname->attributes |= DNS_NAMEATTR_CACHE;
+ aname->attributes |= DNS_NAMEATTR_ANSWER;
+ rdataset->attributes |= DNS_RDATASETATTR_ANSWER;
+ rdataset->attributes |= DNS_RDATASETATTR_CACHE;
+ rdataset->trust = trust;
+ (void)dns_rdataset_additionaldata(rdataset,
+ check_related,
+ fctx);
}
- result = dns_message_nextname(message, DNS_SECTION_ANSWER);
- }
- if (result == ISC_R_NOMORE)
- result = ISC_R_SUCCESS;
- if (result != ISC_R_SUCCESS)
- return (result);
-
- /*
- * We should have found an answer.
- */
- if (!have_answer) {
+ } else if (aname != NULL) {
+ if (!validinanswer(ardataset, fctx))
+ return (DNS_R_FORMERR);
+ if ((ardataset->type == dns_rdatatype_a ||
+ ardataset->type == dns_rdatatype_aaaa) &&
+ !is_answeraddress_allowed(view, aname, ardataset)) {
+ return (DNS_R_SERVFAIL);
+ }
+ if ((ardataset->type == dns_rdatatype_cname ||
+ ardataset->type == dns_rdatatype_dname) &&
+ !is_answertarget_allowed(fctx, qname, aname, ardataset,
+ NULL))
+ {
+ return (DNS_R_SERVFAIL);
+ }
+ aname->attributes |= DNS_NAMEATTR_CACHE;
+ aname->attributes |= DNS_NAMEATTR_ANSWER;
+ ardataset->attributes |= DNS_RDATASETATTR_ANSWER;
+ ardataset->attributes |= DNS_RDATASETATTR_CACHE;
+ ardataset->trust = trust;
+ (void)dns_rdataset_additionaldata(ardataset, check_related,
+ fctx);
+ for (sigrdataset = ISC_LIST_HEAD(aname->list);
+ sigrdataset != NULL;
+ sigrdataset = ISC_LIST_NEXT(sigrdataset, link)) {
+ if (!validinanswer(sigrdataset, fctx))
+ return (DNS_R_FORMERR);
+ if (sigrdataset->type != dns_rdatatype_rrsig ||
+ sigrdataset->covers != type)
+ continue;
+ sigrdataset->attributes |= DNS_RDATASETATTR_ANSWERSIG;
+ sigrdataset->attributes |= DNS_RDATASETATTR_CACHE;
+ sigrdataset->trust = trust;
+ break;
+ }
+ } else if (cname != NULL) {
+ if (!validinanswer(crdataset, fctx)) {
+ return (DNS_R_FORMERR);
+ }
+ if (type == dns_rdatatype_rrsig || type == dns_rdatatype_key ||
+ type == dns_rdatatype_nsec)
+ {
+ char buf[DNS_RDATATYPE_FORMATSIZE];
+ dns_rdatatype_format(type, buf, sizeof(buf));
+ log_formerr(fctx, "CNAME response for %s RR", buf);
+ return (DNS_R_FORMERR);
+ }
+ if (!is_answertarget_allowed(fctx, qname, cname, crdataset,
+ NULL))
+ {
+ return (DNS_R_SERVFAIL);
+ }
+ cname->attributes |= DNS_NAMEATTR_CACHE;
+ cname->attributes |= DNS_NAMEATTR_ANSWER;
+ cname->attributes |= DNS_NAMEATTR_CHAINING;
+ crdataset->attributes |= DNS_RDATASETATTR_ANSWER;
+ crdataset->attributes |= DNS_RDATASETATTR_CACHE;
+ crdataset->attributes |= DNS_RDATASETATTR_CHAINING;
+ crdataset->trust = trust;
+ for (sigrdataset = ISC_LIST_HEAD(cname->list);
+ sigrdataset != NULL;
+ sigrdataset = ISC_LIST_NEXT(sigrdataset, link))
+ {
+ if (!validinanswer(sigrdataset, fctx)) {
+ return (DNS_R_FORMERR);
+ }
+ if (sigrdataset->type != dns_rdatatype_rrsig ||
+ sigrdataset->covers != dns_rdatatype_cname)
+ {
+ continue;
+ }
+ sigrdataset->attributes |= DNS_RDATASETATTR_ANSWERSIG;
+ sigrdataset->attributes |= DNS_RDATASETATTR_CACHE;
+ sigrdataset->trust = trust;
+ break;
+ }
+ chaining = ISC_TRUE;
+ } else if (dname != NULL) {
+ if (!validinanswer(drdataset, fctx)) {
+ return (DNS_R_FORMERR);
+ }
+ if (!is_answertarget_allowed(fctx, qname, dname, drdataset,
+ &chaining)) {
+ return (DNS_R_SERVFAIL);
+ }
+ dname->attributes |= DNS_NAMEATTR_CACHE;
+ dname->attributes |= DNS_NAMEATTR_ANSWER;
+ dname->attributes |= DNS_NAMEATTR_CHAINING;
+ drdataset->attributes |= DNS_RDATASETATTR_ANSWER;
+ drdataset->attributes |= DNS_RDATASETATTR_CACHE;
+ drdataset->attributes |= DNS_RDATASETATTR_CHAINING;
+ drdataset->trust = trust;
+ for (sigrdataset = ISC_LIST_HEAD(dname->list);
+ sigrdataset != NULL;
+ sigrdataset = ISC_LIST_NEXT(sigrdataset, link))
+ {
+ if (!validinanswer(sigrdataset, fctx)) {
+ return (DNS_R_FORMERR);
+ }
+ if (sigrdataset->type != dns_rdatatype_rrsig ||
+ sigrdataset->covers != dns_rdatatype_dname)
+ {
+ continue;
+ }
+ sigrdataset->attributes |= DNS_RDATASETATTR_ANSWERSIG;
+ sigrdataset->attributes |= DNS_RDATASETATTR_CACHE;
+ sigrdataset->trust = trust;
+ break;
+ }
+ } else {
log_formerr(fctx, "reply has no answer");
return (DNS_R_FORMERR);
}
@@ -6536,14 +6340,8 @@ answer_response(fetchctx_t *fctx) {
/*
* Did chaining end before we got the final answer?
*/
- if (chaining != 0) {
- /*
- * Yes. This may be a negative reply, so hand off
- * authority section processing to the noanswer code.
- * If it isn't a noanswer response, no harm will be
- * done.
- */
- return (noanswer_response(fctx, qname, 0));
+ if (chaining) {
+ return (ISC_R_SUCCESS);
}
/*
@@ -6562,11 +6360,9 @@ answer_response(fetchctx_t *fctx) {
* We expect there to be only one owner name for all the rdatasets
* in this section, and we expect that it is not external.
*/
- done = ISC_FALSE;
- ns_name = NULL;
- ns_rdataset = NULL;
result = dns_message_firstname(message, DNS_SECTION_AUTHORITY);
while (!done && result == ISC_R_SUCCESS) {
+ isc_boolean_t external;
name = NULL;
dns_message_currentname(message, DNS_SECTION_AUTHORITY, &name);
external = ISC_TF(!dns_name_issubdomain(name, &fctx->domain));
@@ -6585,12 +6381,13 @@ answer_response(fetchctx_t *fctx) {
DNS_NAMEATTR_CACHE;
rdataset->attributes |=
DNS_RDATASETATTR_CACHE;
- if (aa && chaining == 0)
+ if (aa && !chaining) {
rdataset->trust =
dns_trust_authauthority;
- else
+ } else {
rdataset->trust =
dns_trust_additional;
+ }
if (rdataset->type == dns_rdatatype_ns)
{
@@ -7249,6 +7046,7 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
* Is the remote server broken, or does it dislike us?
*/
if (message->rcode != dns_rcode_noerror &&
+ message->rcode != dns_rcode_yxdomain &&
message->rcode != dns_rcode_nxdomain) {
if (((message->rcode == dns_rcode_formerr ||
message->rcode == dns_rcode_notimp) ||
@@ -7293,13 +7091,6 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
log_formerr(fctx, "server sent FORMERR");
result = DNS_R_FORMERR;
}
- } else if (message->rcode == dns_rcode_yxdomain) {
- /*
- * DNAME mapping failed because the new name
- * was too long. There's no chance of success
- * for this fetch.
- */
- result = DNS_R_YXDOMAIN;
} else if (message->rcode == dns_rcode_badvers) {
unsigned int flags, mask;
unsigned int version;
@@ -7404,6 +7195,7 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
*/
if (message->counts[DNS_SECTION_ANSWER] > 0 &&
(message->rcode == dns_rcode_noerror ||
+ message->rcode == dns_rcode_yxdomain ||
message->rcode == dns_rcode_nxdomain)) {
/*
* [normal case]
--
2.9.3