Github user hanm commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/184#discussion_r111485824
--- 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 --
IIUC, this only verifies that the host name matches what's stored in the
certificates, right? If so, how do we verify that same subject is a valid peer
we intended to connect to, rather than any random server which happens to have
a valid cert? Or is this already taken care of by other parts of code?
For reference, in ZOOKEEPER-1045 what we did for similar verification is by
comparing the name of the server with the name retrieved from Kerberos
principal. The name of the server is retrieved from the zoo.cfg and because of
this we require if users want this verification they need encode the server as
FQDN in zoo.cfg rather than using IP address. Maybe we can do something similar
here.
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