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bind/bind-9.11-CVE-2024-1975.patch
Petr Menšík 70dbc522da Resolve CVE-2024-1975 
6404.	[security]	Remove SIG(0) support from named as a countermeasure
			for CVE-2024-1975. [GL #4480]

Upstream commit 225f2861920b8f8d42a0ea6c34dd1faa93aa8726

Resolves: RHEL-49919
2024-07-30 19:02:41 +02:00

323 lines
12 KiB
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From 5ff88892e43c049659a8a5aef8dfd56c3712daf0 Mon Sep 17 00:00:00 2001
From: Petr Mensik <pemensik@redhat.com>
Date: Tue, 16 Jul 2024 19:49:09 +0200
Subject: [PATCH] Resolve CVE-2024-1975
6404. [security] Remove SIG(0) support from named as a countermeasure
for CVE-2024-1975. [GL #4480]
Resolves: CVE-2024-1975
---
bin/named/client.c | 7 +++
bin/tests/system/tsiggss/authsock.pl | 5 ++
bin/tests/system/tsiggss/tests.sh | 12 ++--
bin/tests/system/upforwd/tests.sh | 21 ++++---
doc/arm/Bv9ARM-book.xml | 22 +++----
lib/dns/message.c | 94 +++-------------------------
6 files changed, 49 insertions(+), 112 deletions(-)
diff --git a/bin/named/client.c b/bin/named/client.c
index 368bc94..ea121b3 100644
--- a/bin/named/client.c
+++ b/bin/named/client.c
@@ -3013,6 +3013,13 @@ client_request(isc_task_t *task, isc_event_t *event) {
ns_client_log(client, DNS_LOGCATEGORY_SECURITY,
NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(3),
"request is signed by a nonauthoritative key");
+ } else if (result == DNS_R_NOTVERIFIEDYET &&
+ client->message->sig0 != NULL)
+ {
+ ns_client_log(client, DNS_LOGCATEGORY_SECURITY,
+ NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(3),
+ "request has a SIG(0) signature but its support "
+ "was removed (CVE-2024-1975)");
} else {
char tsigrcode[64];
isc_buffer_t b;
diff --git a/bin/tests/system/tsiggss/authsock.pl b/bin/tests/system/tsiggss/authsock.pl
index ab3833d..0b231ee 100644
--- a/bin/tests/system/tsiggss/authsock.pl
+++ b/bin/tests/system/tsiggss/authsock.pl
@@ -31,6 +31,10 @@ if (!defined($path)) {
exit(1);
}
+# Enable output autoflush so that it's not lost when the parent sends TERM.
+select STDOUT;
+$| = 1;
+
unlink($path);
my $server = IO::Socket::UNIX->new(Local => $path, Type => SOCK_STREAM, Listen => 8) or
die "unable to create socket $path";
@@ -53,6 +57,7 @@ if ($timeout != 0) {
}
while (my $client = $server->accept()) {
+ printf("accept()\n");
$client->recv(my $buf, 8, 0);
my ($version, $req_len) = unpack('N N', $buf);
diff --git a/bin/tests/system/tsiggss/tests.sh b/bin/tests/system/tsiggss/tests.sh
index 456ce61..d0db388 100644
--- a/bin/tests/system/tsiggss/tests.sh
+++ b/bin/tests/system/tsiggss/tests.sh
@@ -116,7 +116,7 @@ status=$((status+ret))
echo_i "testing external update policy (CNAME) with auth sock ($n)"
ret=0
-$PERL ./authsock.pl --type=CNAME --path=ns1/auth.sock --pidfile=authsock.pid --timeout=120 > /dev/null 2>&1 &
+$PERL ./authsock.pl --type=CNAME --path=ns1/auth.sock --pidfile=authsock.pid --timeout=120 >authsock.log 2>&1 &
sleep 1
test_update $n testcname.example.nil. CNAME "86400 CNAME testdenied.example.nil" "testdenied" || ret=1
n=$((n+1))
@@ -130,17 +130,19 @@ n=$((n+1))
if [ "$ret" -ne 0 ]; then echo_i "failed"; fi
status=$((status+ret))
-echo_i "testing external policy with SIG(0) key ($n)"
+echo_i "testing external policy with unsupported SIG(0) key ($n)"
ret=0
-$NSUPDATE -R $RANDFILE -k ns1/Kkey.example.nil.*.private <<END > /dev/null 2>&1 || ret=1
+$NSUPDATE -R $RANDFILE -k ns1/Kkey.example.nil.*.private <<END >nsupdate.out${n} 2>&1 || true
+debug
server 10.53.0.1 ${PORT}
zone example.nil
update add fred.example.nil 120 cname foo.bar.
send
END
+# update must have failed - SIG(0) signer is not supported
output=`$DIG $DIGOPTS +short cname fred.example.nil.`
-[ -n "$output" ] || ret=1
-[ $ret -eq 0 ] || echo_i "failed"
+[ -n "$output" ] && ret=1
+grep -F "signer=key.example.nil" authsock.log >/dev/null && ret=1
n=$((n+1))
if [ "$ret" -ne 0 ]; then echo_i "failed"; fi
status=$((status+ret))
diff --git a/bin/tests/system/upforwd/tests.sh b/bin/tests/system/upforwd/tests.sh
index ebc9ded..f5b89d4 100644
--- a/bin/tests/system/upforwd/tests.sh
+++ b/bin/tests/system/upforwd/tests.sh
@@ -181,19 +181,22 @@ n=`expr $n + 1`
if test -f keyname
then
- echo_i "checking update forwarding to with sig0 ($n)"
+ echo_i "checking update forwarding to with sig0 (expected to fail) ($n)"
ret=0
keyname=`cat keyname`
- $NSUPDATE -k $keyname.private -- - <<EOF
- local 10.53.0.1
- server 10.53.0.3 ${PORT}
- zone example2
- update add unsigned.example2. 600 A 10.10.10.1
- update add unsigned.example2. 600 TXT Foo
- send
+ # SIG(0) is removed, update is expected to fail.
+ {
+ $NSUPDATE -k $keyname.private -- - <<EOF
+ local 10.53.0.1
+ server 10.53.0.3 ${PORT}
+ zone example2
+ update add unsigned.example2. 600 A 10.10.10.1
+ update add unsigned.example2. 600 TXT Foo
+ send
EOF
+ } >nsupdate.out.$n 2>&1 && ret=1
$DIG -p ${PORT} unsigned.example2 A @10.53.0.1 > dig.out.ns1.test$n
- grep "status: NOERROR" dig.out.ns1.test$n > /dev/null || ret=1
+ grep "status: NOERROR" dig.out.ns1.test$n >/dev/null && ret=1
if [ $ret != 0 ] ; then echo_i "failed"; fi
status=`expr $status + $ret`
n=`expr $n + 1`
diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
index acf772b..563dced 100644
--- a/doc/arm/Bv9ARM-book.xml
+++ b/doc/arm/Bv9ARM-book.xml
@@ -2027,7 +2027,7 @@ allow-update { !{ !localnets; any; }; key host1-host2. ;};
The TKEY process is initiated by a client or server by sending
a query of type TKEY to a TKEY-aware server. The query must include
an appropriate KEY record in the additional section, and
- must be signed using either TSIG or SIG(0) with a previously
+ must be signed using TSIG with a previously
established key. The server's response, if successful,
contains a TKEY record in its answer section. After this transaction,
both participants have enough information to calculate a
@@ -2050,24 +2050,24 @@ allow-update { !{ !localnets; any; }; key host1-host2. ;};
<section xml:id="sig0"><info><title>SIG(0)</title></info>
<para>
- <acronym>BIND</acronym> partially supports DNSSEC SIG(0)
+ <acronym>BIND</acronym> partially supported DNSSEC SIG(0)
transaction signatures as specified in RFC 2535 and RFC 2931.
SIG(0) uses public/private keys to authenticate messages. Access control
- is performed in the same manner as with TSIG keys; privileges can be
+ were performed in the same manner as with TSIG keys; privileges can be
granted or denied in ACL directives based on the key name.
</para>
<para>
- When a SIG(0) signed message is received, it is only
+ When a SIG(0) signed message were received, it were only
verified if the key is known and trusted by the server. The
- server does not attempt to recursively fetch or validate the
+ server did not attempt to recursively fetch or validate the
key.
</para>
<para>
- SIG(0) signing of multiple-message TCP streams is not supported.
+ SIG(0) signing of multiple-message TCP streams were not supported.
</para>
<para>
- The only tool shipped with <acronym>BIND</acronym> 9 that
- generates SIG(0) signed messages is <command>nsupdate</command>.
+ Support for SIG(0) message verification was removed
+ as part of the mitigation of CVE-2024-1975.
</para>
</section>
@@ -12655,7 +12655,7 @@ example.com. NS ns2.example.net.
either grants or denies permission for one or more
names in the zone to be updated by one or more
identities. Identity is determined by the key that
- signed the update request, using either TSIG or SIG(0).
+ signed the update request, using TSIG.
In most cases, <command>update-policy</command> rules
only apply to key-based identities. There is no way
to specify update permissions based on client source
@@ -12742,7 +12742,7 @@ example.com. NS ns2.example.net.
<para>
The <command>identity</command> field must be set to
a fully qualified domain name. In most cases, this
- represents the name of the TSIG or SIG(0) key that must be
+ represents the name of the TSIG key that must be
used to sign the update request. If the specified name is a
wildcard, it is subject to DNS wildcard expansion, and the
rule may apply to multiple identities. When a TKEY exchange
@@ -15952,7 +15952,7 @@ HOST-127.EXAMPLE. MX 0 .
</para>
<para>
ACLs match clients on the basis of up to three characteristics:
- 1) The client's IP address; 2) the TSIG or SIG(0) key that was
+ 1) The client's IP address; 2) the TSIG key that was
used to sign the request, if any; and 3) an address prefix
encoded in an EDNS Client-Subnet option, if any.
</para>
diff --git a/lib/dns/message.c b/lib/dns/message.c
index a44eb2d..9ea2b9e 100644
--- a/lib/dns/message.c
+++ b/lib/dns/message.c
@@ -3373,103 +3373,23 @@ dns_message_dumpsig(dns_message_t *msg, char *txt1) {
isc_result_t
dns_message_checksig(dns_message_t *msg, dns_view_t *view) {
- isc_buffer_t b, msgb;
+ isc_buffer_t msgb;
REQUIRE(DNS_MESSAGE_VALID(msg));
- if (msg->tsigkey == NULL && msg->tsig == NULL && msg->sig0 == NULL)
+ if (msg->tsigkey == NULL && msg->tsig == NULL)
return (ISC_R_SUCCESS);
INSIST(msg->saved.base != NULL);
isc_buffer_init(&msgb, msg->saved.base, msg->saved.length);
isc_buffer_add(&msgb, msg->saved.length);
- if (msg->tsigkey != NULL || msg->tsig != NULL) {
#ifdef SKAN_MSG_DEBUG
- dns_message_dumpsig(msg, "dns_message_checksig#1");
+ dns_message_dumpsig(msg, "dns_message_checksig#1");
#endif
- if (view != NULL)
- return (dns_view_checksig(view, &msgb, msg));
- else
- return (dns_tsig_verify(&msgb, msg, NULL, NULL));
- } else {
- dns_rdata_t rdata = DNS_RDATA_INIT;
- dns_rdata_sig_t sig;
- dns_rdataset_t keyset;
- isc_result_t result;
-
- result = dns_rdataset_first(msg->sig0);
- INSIST(result == ISC_R_SUCCESS);
- dns_rdataset_current(msg->sig0, &rdata);
-
- /*
- * This can occur when the message is a dynamic update, since
- * the rdata length checking is relaxed. This should not
- * happen in a well-formed message, since the SIG(0) is only
- * looked for in the additional section, and the dynamic update
- * meta-records are in the prerequisite and update sections.
- */
- if (rdata.length == 0)
- return (ISC_R_UNEXPECTEDEND);
-
- result = dns_rdata_tostruct(&rdata, &sig, msg->mctx);
- if (result != ISC_R_SUCCESS)
- return (result);
-
- dns_rdataset_init(&keyset);
- if (view == NULL)
- return (DNS_R_KEYUNAUTHORIZED);
- result = dns_view_simplefind(view, &sig.signer,
- dns_rdatatype_key /* SIG(0) */,
- 0, 0, false, &keyset, NULL);
-
- if (result != ISC_R_SUCCESS) {
- /* XXXBEW Should possibly create a fetch here */
- result = DNS_R_KEYUNAUTHORIZED;
- goto freesig;
- } else if (keyset.trust < dns_trust_secure) {
- /* XXXBEW Should call a validator here */
- result = DNS_R_KEYUNAUTHORIZED;
- goto freesig;
- }
- result = dns_rdataset_first(&keyset);
- INSIST(result == ISC_R_SUCCESS);
- for (;
- result == ISC_R_SUCCESS;
- result = dns_rdataset_next(&keyset))
- {
- dst_key_t *key = NULL;
-
- dns_rdata_reset(&rdata);
- dns_rdataset_current(&keyset, &rdata);
- isc_buffer_init(&b, rdata.data, rdata.length);
- isc_buffer_add(&b, rdata.length);
-
- result = dst_key_fromdns(&sig.signer, rdata.rdclass,
- &b, view->mctx, &key);
- if (result != ISC_R_SUCCESS)
- continue;
- if (dst_key_alg(key) != sig.algorithm ||
- dst_key_id(key) != sig.keyid ||
- !(dst_key_proto(key) == DNS_KEYPROTO_DNSSEC ||
- dst_key_proto(key) == DNS_KEYPROTO_ANY))
- {
- dst_key_free(&key);
- continue;
- }
- result = dns_dnssec_verifymessage(&msgb, msg, key);
- dst_key_free(&key);
- if (result == ISC_R_SUCCESS)
- break;
- }
- if (result == ISC_R_NOMORE)
- result = DNS_R_KEYUNAUTHORIZED;
-
- freesig:
- if (dns_rdataset_isassociated(&keyset))
- dns_rdataset_disassociate(&keyset);
- dns_rdata_freestruct(&sig);
- return (result);
- }
+ if (view != NULL)
+ return (dns_view_checksig(view, &msgb, msg));
+ else
+ return (dns_tsig_verify(&msgb, msg, NULL, NULL));
}
#define INDENT(sp) \
--
2.45.2
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