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bind/SOURCES/bind-9.16-CVE-2025-40778.patch

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From 39a43add7ad19fc2d83950a9af0c4f8cf580588b Mon Sep 17 00:00:00 2001
From: Evan Hunt <each@isc.org>
Date: Mon, 29 Sep 2025 21:46:59 -0700
Subject: [PATCH] Tighten restrictions on caching NS RRsets in authority
section
To prevent certain spoofing attacks, a new check has been added
to the existing rules for whether NS data can be cached: the owner
name of the NS RRset must be an ancestor of the name being queried.
(cherry picked from commit fa153f791f9324bf84abf8d259e11c0531fe6e25)
(cherry picked from commit 2f0f44d493c382a7f0a3adfe7c4976b18a3d480b)
Further restrict addresses that are cached when processing referrals
Use the owner name of the NS record as the bailwick apex name
when determining which additional records to cache, rather than
the name of the delegating zone (or a parent thereof).
Modified resolver.c
(cherry picked from commit a41054e9e606a61f1b3c8bc0c54e2f1059347165)
(cherry picked from commit 50479358efdf432d690415131b74b5df158a9d69)
Retry lookups with unsigned DNAME over TCP
To prevent spoofed unsigned DNAME responses being accepted retry
response with unsigned DNAMEs over TCP if the response is not TSIG
signed or there isn't a good DNS CLIENT COOKIE.
To prevent test failures, this required adding TCP support to the
ans3 and ans4 servers in the chain system test.
(cherry picked from commit 2e40705c06831988106335ed77db3cf924d431f6)
(cherry picked from commit 33a7db1fe964e55b76b4ac003ecc56cc67028bd9)
---
bin/tests/system/chain/ans3/ans.pl | 129 -----------------
bin/tests/system/chain/ans3/ans.py | 217 +++++++++++++++++++++++++++++
bin/tests/system/chain/ans4/ans.py | 58 ++++++--
lib/dns/include/dns/message.h | 10 ++
lib/dns/message.c | 12 ++
lib/dns/resolver.c | 114 ++++++++++++---
6 files changed, 380 insertions(+), 160 deletions(-)
delete mode 100644 bin/tests/system/chain/ans3/ans.pl
create mode 100644 bin/tests/system/chain/ans3/ans.py
diff --git a/bin/tests/system/chain/ans3/ans.pl b/bin/tests/system/chain/ans3/ans.pl
deleted file mode 100644
index 31d22d807b..0000000000
--- a/bin/tests/system/chain/ans3/ans.pl
+++ /dev/null
@@ -1,129 +0,0 @@
-#!/usr/bin/env perl
-#
-# Copyright (C) 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 https://mozilla.org/MPL/2.0/.
-#
-# See the COPYRIGHT file distributed with this work for additional
-# information regarding copyright ownership.
-
-use strict;
-use warnings;
-
-use IO::File;
-use Getopt::Long;
-use Net::DNS::Nameserver;
-
-my $pidf = new IO::File "ans.pid", "w" or die "cannot open pid file: $!";
-print $pidf "$$\n" or die "cannot write pid file: $!";
-$pidf->close or die "cannot close pid file: $!";
-sub rmpid { unlink "ans.pid"; exit 1; };
-
-$SIG{INT} = \&rmpid;
-$SIG{TERM} = \&rmpid;
-
-my $localaddr = "10.53.0.3";
-
-my $localport = int($ENV{'PORT'});
-if (!$localport) { $localport = 5300; }
-
-my $verbose = 0;
-my $ttl = 60;
-my $zone = "example.broken";
-my $nsname = "ns3.$zone";
-my $synth = "synth-then-dname.$zone";
-my $synth2 = "synth2-then-dname.$zone";
-
-sub reply_handler {
- my ($qname, $qclass, $qtype, $peerhost, $query, $conn) = @_;
- my ($rcode, @ans, @auth, @add);
-
- print ("request: $qname/$qtype\n");
- STDOUT->flush();
-
- if ($qname eq "example.broken") {
- if ($qtype eq "SOA") {
- my $rr = new Net::DNS::RR("$qname $ttl $qclass SOA . . 0 0 0 0 0");
- push @ans, $rr;
- } elsif ($qtype eq "NS") {
- my $rr = new Net::DNS::RR("$qname $ttl $qclass NS $nsname");
- push @ans, $rr;
- $rr = new Net::DNS::RR("$nsname $ttl $qclass A $localaddr");
- push @add, $rr;
- }
- $rcode = "NOERROR";
- } elsif ($qname eq "cname-to-$synth2") {
- my $rr = new Net::DNS::RR("$qname $ttl $qclass CNAME name.$synth2");
- push @ans, $rr;
- $rr = new Net::DNS::RR("name.$synth2 $ttl $qclass CNAME name");
- push @ans, $rr;
- $rr = new Net::DNS::RR("$synth2 $ttl $qclass DNAME .");
- push @ans, $rr;
- $rcode = "NOERROR";
- } elsif ($qname eq "$synth" || $qname eq "$synth2") {
- if ($qtype eq "DNAME") {
- my $rr = new Net::DNS::RR("$qname $ttl $qclass DNAME .");
- push @ans, $rr;
- }
- $rcode = "NOERROR";
- } elsif ($qname eq "name.$synth") {
- my $rr = new Net::DNS::RR("$qname $ttl $qclass CNAME name.");
- push @ans, $rr;
- $rr = new Net::DNS::RR("$synth $ttl $qclass DNAME .");
- push @ans, $rr;
- $rcode = "NOERROR";
- } elsif ($qname eq "name.$synth2") {
- my $rr = new Net::DNS::RR("$qname $ttl $qclass CNAME name.");
- push @ans, $rr;
- $rr = new Net::DNS::RR("$synth2 $ttl $qclass DNAME .");
- push @ans, $rr;
- $rcode = "NOERROR";
- # The following three code branches referring to the "example.dname"
- # zone are necessary for the resolver variant of the CVE-2021-25215
- # regression test to work. A named instance cannot be used for
- # serving the DNAME records below as a version of BIND vulnerable to
- # CVE-2021-25215 would crash while answering the queries asked by
- # the tested resolver.
- } elsif ($qname eq "ns3.example.dname") {
- if ($qtype eq "A") {
- my $rr = new Net::DNS::RR("$qname $ttl $qclass A 10.53.0.3");
- push @ans, $rr;
- }
- if ($qtype eq "AAAA") {
- my $rr = new Net::DNS::RR("example.dname. $ttl $qclass SOA . . 0 0 0 0 $ttl");
- push @auth, $rr;
- }
- $rcode = "NOERROR";
- } elsif ($qname eq "self.example.self.example.dname") {
- my $rr = new Net::DNS::RR("self.example.dname. $ttl $qclass DNAME dname.");
- push @ans, $rr;
- $rr = new Net::DNS::RR("$qname $ttl $qclass CNAME self.example.dname.");
- push @ans, $rr;
- $rcode = "NOERROR";
- } elsif ($qname eq "self.example.dname") {
- if ($qtype eq "DNAME") {
- my $rr = new Net::DNS::RR("$qname $ttl $qclass DNAME dname.");
- push @ans, $rr;
- }
- $rcode = "NOERROR";
- } else {
- $rcode = "REFUSED";
- }
- return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
-}
-
-GetOptions(
- 'port=i' => \$localport,
- 'verbose!' => \$verbose,
-);
-
-my $ns = Net::DNS::Nameserver->new(
- LocalAddr => $localaddr,
- LocalPort => $localport,
- ReplyHandler => \&reply_handler,
- Verbose => $verbose,
-);
-
-$ns->main_loop;
diff --git a/bin/tests/system/chain/ans3/ans.py b/bin/tests/system/chain/ans3/ans.py
new file mode 100644
index 0000000000..0a031c1145
--- /dev/null
+++ b/bin/tests/system/chain/ans3/ans.py
@@ -0,0 +1,217 @@
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# 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 https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+############################################################################
+# ans.py: See README.anspy for details.
+############################################################################
+
+from __future__ import print_function
+import os
+import sys
+import signal
+import socket
+import select
+from datetime import datetime, timedelta
+import functools
+
+import dns, dns.message, dns.query
+from dns.rdatatype import *
+from dns.rdataclass import *
+from dns.rcode import *
+from dns.name import *
+
+
+############################################################################
+# Respond to a DNS query.
+############################################################################
+def create_response(msg):
+ ttl = 60
+ zone = "example.broken."
+ nsname = f"ns3.{zone}"
+ synth = f"synth-then-dname.{zone}"
+ synth2 = f"synth2-then-dname.{zone}"
+
+ m = dns.message.from_wire(msg)
+ qname = m.question[0].name.to_text()
+
+ # prepare the response and convert to wire format
+ r = dns.message.make_response(m)
+
+ # get qtype
+ rrtype = m.question[0].rdtype
+ qtype = dns.rdatatype.to_text(rrtype)
+ print(f"request: {qname}/{qtype}")
+
+ rcode = "NOERROR"
+ if qname == zone:
+ if qtype == "SOA":
+ r.answer.append(dns.rrset.from_text(qname, ttl, IN, SOA, ". . 0 0 0 0 0"))
+ elif qtype == "NS":
+ r.answer.append(dns.rrset.from_text(qname, ttl, IN, NS, nsname))
+ r.additional.append(dns.rrset.from_text(nsname, ttl, IN, A, ip4))
+ elif qname == f"cname-to-{synth2}":
+ r.answer.append(dns.rrset.from_text(qname, ttl, IN, CNAME, f"name.{synth2}"))
+ r.answer.append(dns.rrset.from_text(f"name.{synth2}", ttl, IN, CNAME, "name."))
+ r.answer.append(dns.rrset.from_text(synth2, ttl, IN, DNAME, "."))
+ elif qname == f"{synth}" or qname == f"{synth2}":
+ if qtype == "DNAME":
+ r.answer.append(dns.rrset.from_text(qname, ttl, IN, DNAME, "."))
+ elif qname == f"name.{synth}":
+ r.answer.append(dns.rrset.from_text(qname, ttl, IN, CNAME, "name."))
+ r.answer.append(dns.rrset.from_text(synth, ttl, IN, DNAME, "."))
+ elif qname == f"name.{synth2}":
+ r.answer.append(dns.rrset.from_text(qname, ttl, IN, CNAME, "name."))
+ r.answer.append(dns.rrset.from_text(synth2, ttl, IN, DNAME, "."))
+ elif qname == "ns3.example.dname.":
+ # This and the next two code branches referring to the "example.dname"
+ # zone are necessary for the resolver variant of the CVE-2021-25215
+ # regression test to work. A named instance cannot be used for
+ # serving the DNAME records below as a version of BIND vulnerable to
+ # CVE-2021-25215 would crash while answering the queries asked by
+ # the tested resolver.
+ if qtype == "A":
+ r.answer.append(dns.rrset.from_text(qname, ttl, IN, A, ip4))
+ elif qtype == "AAAA":
+ r.authority.append(
+ dns.rrset.from_text("example.dname.", ttl, IN, SOA, ". . 0 0 0 0 0")
+ )
+ elif qname == "self.example.self..example.dname.":
+ r.answer.append(
+ dns.rrset.from_text("self.example.dname.", ttl, IN, DNAME, "dname.")
+ )
+ r.answer.append(
+ dns.rrset.from_text(qname, ttl, IN, CNAME, "self.example.dname.")
+ )
+ elif qname == "self.example.dname.":
+ if qtype == "DNAME":
+ r.answer.append(dns.rrset.from_text(qname, ttl, IN, DNAME, "dname."))
+ else:
+ rcode = "REFUSED"
+
+ r.flags |= dns.flags.AA
+ r.use_edns()
+ return r.to_wire()
+
+
+def sigterm(signum, frame):
+ print("Shutting down now...")
+ os.remove("ans.pid")
+ running = False
+ sys.exit(0)
+
+
+############################################################################
+# Main
+#
+# Set up responder and control channel, open the pid file, and start
+# the main loop, listening for queries on the query channel or commands
+# on the control channel and acting on them.
+############################################################################
+ip4 = "10.53.0.3"
+ip6 = "fd92:7065:b8e:ffff::3"
+
+try:
+ port = int(os.environ["PORT"])
+except:
+ port = 5300
+
+query4_udp = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+query4_udp.bind((ip4, port))
+
+query4_tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+query4_tcp.bind((ip4, port))
+query4_tcp.listen(1)
+query4_tcp.settimeout(1)
+
+havev6 = True
+try:
+ query6_udp = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
+ try:
+ query6_udp.bind((ip6, port))
+ except:
+ query6_udp.close()
+ havev6 = False
+
+ query6_tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+ try:
+ query6_tcp.bind((ip4, port))
+ query6_tcp.listen(1)
+ query6_tcp.settimeout(1)
+ except:
+ query6_tcp.close()
+ havev6 = False
+except:
+ havev6 = False
+
+signal.signal(signal.SIGTERM, sigterm)
+
+f = open("ans.pid", "w")
+pid = os.getpid()
+print(pid, file=f)
+f.close()
+
+running = True
+
+print("Listening on %s port %d" % (ip4, port))
+if havev6:
+ print("Listening on %s port %d" % (ip6, port))
+print("Ctrl-c to quit")
+
+if havev6:
+ input = [query4_udp, query4_tcp, query6_udp, query6_tcp]
+else:
+ input = [query4_udp, query4_tcp]
+
+while running:
+ try:
+ inputready, outputready, exceptready = select.select(input, [], [])
+ except select.error as e:
+ break
+ except socket.error as e:
+ break
+ except KeyboardInterrupt:
+ break
+
+ for s in inputready:
+ if s == query4_udp or s == query6_udp:
+ print("Query received on %s" % (ip4 if s == query4_udp else ip6))
+ # Handle incoming queries
+ msg = s.recvfrom(65535)
+ rsp = create_response(msg[0])
+ if rsp:
+ s.sendto(rsp, msg[1])
+ elif s == query4_tcp or s == query6_tcp:
+ try:
+ conn, _ = s.accept()
+ if s == query4_tcp or s == query6_tcp:
+ print(
+ "TCP Query received on %s" % (ip4 if s == query4_tcp else ip6),
+ end=" ",
+ )
+ # get TCP message length
+ msg = conn.recv(2)
+ if len(msg) != 2:
+ print("couldn't read TCP message length")
+ continue
+ length = struct.unpack(">H", msg[:2])[0]
+ msg = conn.recv(length)
+ if len(msg) != length:
+ print("couldn't read TCP message")
+ continue
+ rsp = create_response(msg)
+ if rsp:
+ conn.send(struct.pack(">H", len(rsp)))
+ conn.send(rsp)
+ conn.close()
+ except socket.error as e:
+ print("error: %s" % str(e))
+ if not running:
+ break
diff --git a/bin/tests/system/chain/ans4/ans.py b/bin/tests/system/chain/ans4/ans.py
index 45d650417f..e4fc15a280 100755
--- a/bin/tests/system/chain/ans4/ans.py
+++ b/bin/tests/system/chain/ans4/ans.py
@@ -276,16 +276,30 @@ except: port=5300
try: ctrlport=int(os.environ['EXTRAPORT1'])
except: ctrlport=5300
-query4_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
-query4_socket.bind((ip4, port))
+query4_udp = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+query4_udp.bind((ip4, port))
+
+query4_tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+query4_tcp.bind((ip4, port))
+query4_tcp.listen(1)
+query4_tcp.settimeout(1)
havev6 = True
try:
- query6_socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
+ query6_udp = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
+ try:
+ query6_udp.bind((ip6, port))
+ except:
+ query6_udp.close()
+ havev6 = False
+
+ query6_tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
- query6_socket.bind((ip6, port))
+ query6_tcp.bind((ip4, port))
+ query6_tcp.listen(1)
+ query6_tcp.settimeout(1)
except:
- query6_socket.close()
+ query6_tcp.close()
havev6 = False
except:
havev6 = False
@@ -310,9 +324,9 @@ print ("Control channel on %s port %d" % (ip4, ctrlport))
print ("Ctrl-c to quit")
if havev6:
- input = [query4_socket, query6_socket, ctrl_socket]
+ input = [query4_udp, query4_tcp, query6_udp, query6_tcp, ctrl_socket]
else:
- input = [query4_socket, ctrl_socket]
+ input = [query4_udp, query4_tcp, ctrl_socket]
while running:
try:
@@ -335,13 +349,37 @@ while running:
break
ctl_channel(msg)
conn.close()
- if s == query4_socket or s == query6_socket:
- print ("Query received on %s" %
- (ip4 if s == query4_socket else ip6))
+ elif s == query4_udp or s == query6_udp:
+ print("Query received on %s" % (ip4 if s == query4_udp else ip6))
# Handle incoming queries
msg = s.recvfrom(65535)
rsp = create_response(msg[0])
if rsp:
s.sendto(rsp, msg[1])
+ elif s == query4_tcp or s == query6_tcp:
+ try:
+ conn, _ = s.accept()
+ if s == query4_tcp or s == query6_tcp:
+ print(
+ "TCP Query received on %s" % (ip4 if s == query4_tcp else ip6),
+ end=" ",
+ )
+ # get TCP message length
+ msg = conn.recv(2)
+ if len(msg) != 2:
+ print("couldn't read TCP message length")
+ continue
+ length = struct.unpack(">H", msg[:2])[0]
+ msg = conn.recv(length)
+ if len(msg) != length:
+ print("couldn't read TCP message")
+ continue
+ rsp = create_response(msg)
+ if rsp:
+ conn.send(struct.pack(">H", len(rsp)))
+ conn.send(rsp)
+ conn.close()
+ except socket.error as e:
+ print("error: %s" % str(e))
if not running:
break
diff --git a/lib/dns/include/dns/message.h b/lib/dns/include/dns/message.h
index 68c13ee6c5..53c96a5827 100644
--- a/lib/dns/include/dns/message.h
+++ b/lib/dns/include/dns/message.h
@@ -1,6 +1,8 @@
/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
+ * SPDX-License-Identifier: MPL-2.0
+ *
* 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 https://mozilla.org/MPL/2.0/.
@@ -233,6 +235,7 @@ struct dns_message {
unsigned int cc_bad : 1;
unsigned int tkey : 1;
unsigned int rdclass_set : 1;
+ unsigned int has_dname : 1;
unsigned int opt_reserved;
unsigned int sig_reserved;
@@ -1449,4 +1452,11 @@ dns_message_clonebuffer(dns_message_t *msg);
* \li msg be a valid message.
*/
+bool
+dns_message_hasdname(dns_message_t *msg);
+/*%<
+ * Return whether a DNAME was detected in the ANSWER section of a QUERY
+ * message when it was parsed.
+ */
+
ISC_LANG_ENDDECLS
diff --git a/lib/dns/message.c b/lib/dns/message.c
index 04315bc6d0..aa434a75f1 100644
--- a/lib/dns/message.c
+++ b/lib/dns/message.c
@@ -438,6 +438,7 @@ msginit(dns_message_t *m) {
m->cc_bad = 0;
m->tkey = 0;
m->rdclass_set = 0;
+ m->has_dname = 0;
m->querytsig = NULL;
m->indent.string = "\t";
m->indent.count = 0;
@@ -1717,6 +1718,11 @@ getsection(isc_buffer_t *source, dns_message_t *msg, dns_decompress_t *dctx,
*/
msg->tsigname->attributes |= DNS_NAMEATTR_NOCOMPRESS;
free_name = false;
+ } else if (rdtype == dns_rdatatype_dname &&
+ sectionid == DNS_SECTION_ANSWER &&
+ msg->opcode == dns_opcode_query)
+ {
+ msg->has_dname = 1;
}
rdataset = NULL;
@@ -4750,3 +4756,9 @@ dns_message_clonebuffer(dns_message_t *msg) {
msg->free_query = 1;
}
}
+
+bool
+dns_message_hasdname(dns_message_t *msg) {
+ REQUIRE(DNS_MESSAGE_VALID(msg));
+ return msg->has_dname;
+}
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index ad0a1b8102..5973bc1d55 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -751,6 +751,7 @@ typedef struct respctx {
bool get_nameservers; /* get a new NS rrset at
* zone cut? */
bool resend; /* resend this query? */
+ bool secured; /* message was signed or had a valid cookie */
bool nextitem; /* invalid response; keep
* listening for the correct one */
bool truncated; /* response was truncated */
@@ -7155,7 +7156,8 @@ mark_related(dns_name_t *name, dns_rdataset_t *rdataset, bool external,
* locally served zone.
*/
static inline bool
-name_external(const dns_name_t *name, dns_rdatatype_t type, fetchctx_t *fctx) {
+name_external(const dns_name_t *name, dns_rdatatype_t type, respctx_t *rctx) {
+ fetchctx_t *fctx = rctx->fctx;
isc_result_t result;
dns_forwarders_t *forwarders = NULL;
dns_fixedname_t fixed, zfixed;
@@ -7167,7 +7169,9 @@ name_external(const dns_name_t *name, dns_rdatatype_t type, fetchctx_t *fctx) {
unsigned int labels;
dns_namereln_t rel;
- apex = ISFORWARDER(fctx->addrinfo) ? fctx->fwdname : &fctx->domain;
+ apex = (/*ISDUALSTACK(fctx->addrinfo) || */!ISFORWARDER(fctx->addrinfo))
+ ? rctx->ns_name != NULL ? rctx->ns_name : &fctx->domain
+ : fctx->fwdname;
/*
* The name is outside the queried namespace.
@@ -7275,7 +7279,7 @@ check_section(void *arg, const dns_name_t *addname, dns_rdatatype_t type,
result = dns_message_findname(rctx->query->rmessage, section, addname,
dns_rdatatype_any, 0, &name, NULL);
if (result == ISC_R_SUCCESS) {
- external = name_external(name, type, fctx);
+ external = name_external(name, type, rctx);
if (type == dns_rdatatype_a) {
for (rdataset = ISC_LIST_HEAD(name->list);
rdataset != NULL;
@@ -7884,6 +7888,47 @@ betterreferral(respctx_t *rctx) {
return (false);
}
+static bool
+rctx_need_tcpretry(respctx_t *rctx) {
+ resquery_t *query = rctx->query;
+ if ((rctx->retryopts & DNS_FETCHOPT_TCP) != 0) {
+ /* TCP is already in the retry flags */
+ return false;
+ }
+
+ /*
+ * If the message was secured, no need to continue.
+ */
+ if (rctx->secured) {
+ return false;
+ }
+
+ /*
+ * Currently the only extra reason why we might need to
+ * retry a UDP response over TCP is a DNAME in the message.
+ */
+ if (dns_message_hasdname(query->rmessage)) {
+ return true;
+ }
+
+ return false;
+}
+
+static isc_result_t
+rctx_tcpretry(respctx_t *rctx) {
+ /*
+ * Do we need to retry a UDP response over TCP?
+ */
+ if (rctx_need_tcpretry(rctx)) {
+ rctx->retryopts |= DNS_FETCHOPT_TCP;
+ rctx->resend = true;
+ rctx_done(rctx, ISC_R_SUCCESS);
+ return ISC_R_COMPLETE;
+ }
+
+ return ISC_R_SUCCESS;
+}
+
/*
* resquery_response():
* Handles responses received in response to iterative queries sent by
@@ -8042,6 +8087,11 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
break;
}
+ /*
+ * The dispatcher should ensure we only get responses with QR set.
+ */
+ INSIST((query->rmessage->flags & DNS_MESSAGEFLAG_QR) != 0);
+
/*
* If the message is signed, check the signature. If not, this
* returns success anyway.
@@ -8058,9 +8108,16 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
}
/*
- * The dispatcher should ensure we only get responses with QR set.
+ * Remember whether this message was signed or had a
+ * valid client cookie; if not, we may need to retry over
+ * TCP later.
*/
- INSIST((query->rmessage->flags & DNS_MESSAGEFLAG_QR) != 0);
+ if (query->rmessage->cc_ok || query->rmessage->tsig != NULL ||
+ query->rmessage->sig0 != NULL)
+ {
+ rctx.secured = true;
+ }
+
/*
* INSIST() that the message comes from the place we sent it to,
* since the dispatch code should ensure this.
@@ -8074,10 +8131,7 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
* This may be a misconfigured anycast server or an attempt to send
* a spoofed response. Skip if we have a valid tsig.
*/
- if (dns_message_gettsig(query->rmessage, NULL) == NULL &&
- !query->rmessage->cc_ok && !query->rmessage->cc_bad &&
- (rctx.retryopts & DNS_FETCHOPT_TCP) == 0)
- {
+ if (!rctx.secured && (rctx.retryopts & DNS_FETCHOPT_TCP) == 0) {
unsigned char cookie[COOKIE_BUFFER_SIZE];
if (dns_adb_getcookie(fctx->adb, query->addrinfo, cookie,
sizeof(cookie)) > CLIENT_COOKIE_SIZE)
@@ -8103,6 +8157,17 @@ resquery_response(isc_task_t *task, isc_event_t *event) {
*/
}
+ /*
+ * Check whether we need to retry over TCP for some other reason.
+ */
+ result = rctx_tcpretry(&rctx);
+ if (result == ISC_R_COMPLETE) {
+ return;
+ }
+
+ /*
+ * Check for EDNS issues.
+ */
rctx_edns(&rctx);
/*
@@ -8830,8 +8895,8 @@ rctx_answer_positive(respctx_t *rctx) {
}
/*
- * Cache records in the authority section, if
- * there are any suitable for caching.
+ * Cache records in the authority section, if there are
+ * any suitable for caching.
*/
rctx_authority_positive(rctx);
@@ -8902,7 +8967,7 @@ rctx_answer_scan(respctx_t *rctx) {
/*
* Don't accept DNAME from parent namespace.
*/
- if (name_external(name, dns_rdatatype_dname, fctx)) {
+ if (name_external(name, dns_rdatatype_dname, rctx)) {
continue;
}
@@ -9200,14 +9265,14 @@ rctx_answer_dname(respctx_t *rctx) {
/*
* rctx_authority_positive():
- * Examine the records in the authority section (if there are any) for a
- * positive answer. We expect the names for all rdatasets in this section
- * to be subdomains of the domain being queried; any that are not are
- * skipped. We expect to find only *one* owner name; any names
- * after the first one processed are ignored. We expect to find only
- * rdatasets of type NS, RRSIG, or SIG; all others are ignored. Whatever
- * remains can be cached at trust level authauthority or additional
- * (depending on whether the AA bit was set on the answer).
+ * If a positive answer was received over TCP or secured with a cookie
+ * or TSIG, examine the authority section. We expect names for all
+ * rdatasets in this section to be subdomains of the domain being queried;
+ * any that are not are skipped. We expect to find only *one* owner name;
+ * any names after the first one processed are ignored. We expect to find
+ * only rdatasets of type NS; all others are ignored. Whatever remains can
+ * be cached at trust level authauthority or additional (depending on
+ * whether the AA bit was set on the answer).
*/
static void
rctx_authority_positive(respctx_t *rctx) {
@@ -9215,6 +9280,11 @@ rctx_authority_positive(respctx_t *rctx) {
bool done = false;
isc_result_t result;
+ /* If it's spoofable, don't cache it. */
+ if (!rctx->secured && (rctx->query->options & DNS_FETCHOPT_TCP) == 0) {
+ return;
+ }
+
result = dns_message_firstname(rctx->query->rmessage,
DNS_SECTION_AUTHORITY);
while (!done && result == ISC_R_SUCCESS) {
@@ -9223,7 +9293,9 @@ rctx_authority_positive(respctx_t *rctx) {
dns_message_currentname(rctx->query->rmessage,
DNS_SECTION_AUTHORITY, &name);
- if (!name_external(name, dns_rdatatype_ns, fctx)) {
+ if (!name_external(name, dns_rdatatype_ns, rctx) &&
+ dns_name_issubdomain(&fctx->name, name))
+ {
dns_rdataset_t *rdataset = NULL;
/*
--
2.51.1
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