Github user afine commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/184#discussion_r111612166
--- Diff: src/java/main/org/apache/zookeeper/common/ZKTrustManager.java ---
@@ -0,0 +1,137 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.zookeeper.common;
+
+import org.apache.http.conn.ssl.DefaultHostnameVerifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.net.ssl.SSLEngine;
+import javax.net.ssl.SSLException;
+import javax.net.ssl.X509ExtendedTrustManager;
+import java.net.InetAddress;
+import java.net.Socket;
+import java.net.UnknownHostException;
+import java.security.cert.CertificateException;
+import java.security.cert.X509Certificate;
+
+/**
+ * A custom TrustManager that supports hostname verification via
org.apache.http.conn.ssl.DefaultHostnameVerifier.
+ *
+ * We attempt to perform verification using just the IP address first and
if that fails will attempt to perform a
+ * reverse DNS lookup and verify using the hostname.
+ */
+public class ZKTrustManager extends X509ExtendedTrustManager {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(ZKTrustManager.class);
+
+ private X509ExtendedTrustManager x509ExtendedTrustManager;
+ private boolean hostnameVerificationEnabled;
+ private boolean shouldVerifyClientHostname;
+
+ private DefaultHostnameVerifier hostnameVerifier;
+
+ /**
+ * Instantiate a new ZKTrustManager.
+ *
+ * @param x509ExtendedTrustManager The trustmanager to use for
checkClientTrusted/checkServerTrusted logic
+ * @param hostnameVerificationEnabled If true, this TrustManager
should verify hostnames.
+ * @param shouldVerifyClientHostname If true, and
hostnameVerificationEnabled is true, the hostname of a client
+ * connecting to this machine will
be verified in addition to the servers that this
+ * instance connects to. If false,
and hostnameVerificationEnabled is true, only
+ * the hostnames of servers that
this instance connects to will be verified. If
+ * hostnameVerificationEnabled is
false, this argument is ignored.
+ */
+ public ZKTrustManager(X509ExtendedTrustManager
x509ExtendedTrustManager, boolean hostnameVerificationEnabled, boolean
shouldVerifyClientHostname) {
+ this.x509ExtendedTrustManager = x509ExtendedTrustManager;
+ this.hostnameVerificationEnabled = hostnameVerificationEnabled;
+ this.shouldVerifyClientHostname = shouldVerifyClientHostname;
+
+ hostnameVerifier = new DefaultHostnameVerifier();
+ }
+
+ @Override
+ public X509Certificate[] getAcceptedIssuers() {
+ return x509ExtendedTrustManager.getAcceptedIssuers();
+ }
+
+ @Override
+ public void checkClientTrusted(X509Certificate[] chain, String
authType, Socket socket) throws CertificateException {
+ if (hostnameVerificationEnabled && shouldVerifyClientHostname) {
+ performHostVerification(socket.getInetAddress(), chain[0]);
+ }
+ x509ExtendedTrustManager.checkClientTrusted(chain, authType,
socket);
+ }
+
+ @Override
+ public void checkServerTrusted(X509Certificate[] chain, String
authType, Socket socket) throws CertificateException {
+ if (hostnameVerificationEnabled) {
+ performHostVerification(socket.getInetAddress(), chain[0]);
+ }
+ x509ExtendedTrustManager.checkServerTrusted(chain, authType,
socket);
+ }
+
+ @Override
+ public void checkClientTrusted(X509Certificate[] chain, String
authType, SSLEngine engine) throws CertificateException {
+ if (hostnameVerificationEnabled && shouldVerifyClientHostname) {
+ try {
+
performHostVerification(InetAddress.getByName(engine.getPeerHost()), chain[0]);
+ } catch (UnknownHostException e) {
+ throw new CertificateException("failed to verify host", e);
+ }
+ }
+ x509ExtendedTrustManager.checkServerTrusted(chain, authType,
engine);
+ }
+
+ @Override
+ public void checkServerTrusted(X509Certificate[] chain, String
authType, SSLEngine engine) throws CertificateException {
+ if (hostnameVerificationEnabled) {
+ try {
+
performHostVerification(InetAddress.getByName(engine.getPeerHost()), chain[0]);
+ } catch (UnknownHostException e) {
+ throw new CertificateException("failed to verify host", e);
+ }
+ }
+ x509ExtendedTrustManager.checkServerTrusted(chain, authType,
engine);
+ }
+
+ @Override
+ public void checkClientTrusted(X509Certificate[] chain, String
authType) throws CertificateException {
+ x509ExtendedTrustManager.checkClientTrusted(chain, authType);
+ }
+
+ @Override
+ public void checkServerTrusted(X509Certificate[] chain, String
authType) throws CertificateException {
+ x509ExtendedTrustManager.checkServerTrusted(chain, authType);
+ }
+
+ private void performHostVerification(InetAddress inetAddress,
X509Certificate certificate) throws CertificateException {
+ try {
+ hostnameVerifier.verify(inetAddress.getHostAddress(),
certificate);
--- End diff --
So we have a few hostname checks that we could consider. Please let me know
if I am missing any.
1. Check that the address/hostname of the machine matches what is listed on
the certificate
2. Check that the address/hostname of the machine matches what is expected
from zoo.cfg (this may also require reading the sid from the packet sent when a
connection is established).
3. Check that the address/hostname listed on the certificate matches what
is expected from zoo.cfg
This patch only performs check 1. I think that check 3 is something
@geek101 mentioned earlier and we agreed this can be moved to another patch as
it is more complicated.
I think it is also possible to implement check 2. This can exist entirely
outside of tls/ssl support and is something we should consider based on its own
merits.
I think having checks 1 and 2 would be plenty secure and we would not need
check 3.
Let me know what you think @hanm.
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