HADOOP-15418. Hadoop KMSAuthenticationFilter needs to use getPropsByPrefix instead of iterator to avoid ConcurrentModificationException. Contributed by lqjack and Suma Shivaprasad

hadoop-common-project/hadoop-kms/src/main/java/org/apache/hadoop/crypto/key/kms/server/KMSAuthenticationFilter.java

@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.crypto.key.kms.server;
 
+import com.google.common.annotations.VisibleForTesting;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.crypto.key.kms.KMSDelegationToken;
@@ -54,16 +55,22 @@ public class KMSAuthenticationFilter
   @Override
   protected Properties getConfiguration(String configPrefix,
       FilterConfig filterConfig) {
-    Properties props = new Properties();
+
     Configuration conf = KMSWebApp.getConfiguration();
-    for (Map.Entry<String, String> entry : conf) {
+    return getKMSConfiguration(conf);
-      String name = entry.getKey();
-      if (name.startsWith(CONFIG_PREFIX)) {
-        String value = conf.get(name);
-        name = name.substring(CONFIG_PREFIX.length());
-        props.setProperty(name, value);
   }
+
+  @VisibleForTesting
+  Properties getKMSConfiguration(Configuration conf) {
+    Properties props = new Properties();
+
+    Map<String, String> propsWithPrefixMap = conf.getPropsWithPrefix(
+        CONFIG_PREFIX);
+
+    for (Map.Entry<String, String> entry : propsWithPrefixMap.entrySet()) {
+      props.setProperty(entry.getKey(), entry.getValue());
     }
+
     String authType = props.getProperty(AUTH_TYPE);
     if (authType.equals(PseudoAuthenticationHandler.TYPE)) {
       props.setProperty(AUTH_TYPE,

hadoop-common-project/hadoop-kms/src/test/java/org/apache/hadoop/crypto/key/kms/server/TestKMSAuthenticationFilter.java

@@ -0,0 +1,48 @@
+/**
+ * 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.hadoop.crypto.key.kms.server;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.crypto.key.kms.KMSDelegationToken;
+import org.apache.hadoop.security.token.delegation.web
+    .DelegationTokenAuthenticationHandler;
+import org.apache.hadoop.security.token.delegation.web
+    .PseudoDelegationTokenAuthenticationHandler;
+import org.junit.Test;
+import java.util.Properties;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Test KMS Authentication Filter.
+ */
+public class TestKMSAuthenticationFilter {
+
+  @Test public void testConfiguration() throws Exception {
+    Configuration conf = new Configuration();
+    conf.set("hadoop.kms.authentication.type", "simple");
+
+    Properties prop = new KMSAuthenticationFilter().getKMSConfiguration(conf);
+    assertEquals(prop.getProperty(KMSAuthenticationFilter.AUTH_TYPE),
+        PseudoDelegationTokenAuthenticationHandler.class.getName());
+    assertEquals(
+        prop.getProperty(DelegationTokenAuthenticationHandler.TOKEN_KIND),
+        KMSDelegationToken.TOKEN_KIND_STR);
+  }
+}
+