hardening SocketServer ongoing work

examples/socketServer.properties

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+# 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.
+
+
+# An example log4j configuration file that outputs to System.out.  The
+# output information consists of relative time, log level, thread
+# name, logger name, nested diagnostic context and the message in that
+# order.
+
+# For the general syntax of property based configuration files see the
+# documenation of org.apache.log4j.PropertyConfigurator.
+
+log4j.rootLogger=DEBUG, A1
+
+# A1 is set to be a ConsoleAppender which outputs to System.out. 
+log4j.appender.A1=org.apache.log4j.ConsoleAppender
+
+# A1 uses PatternLayout.
+log4j.appender.A1.layout=org.apache.log4j.PatternLayout
+
+# The conversion pattern uses format specifiers. You might want to
+# change the pattern an watch the output format change.
+log4j.appender.A1.layout.ConversionPattern=%-4r %-5p [%t] %37c %3x - %m%n
+
+

src/main/java/org/apache/log4j/net/HardenedLoggingEventInputStream.java

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+/*
+ * 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.log4j.net;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.log4j.Level;
+import org.apache.log4j.Priority;
+import org.apache.log4j.spi.LocationInfo;
+import org.apache.log4j.spi.LoggingEvent;
+import org.apache.log4j.spi.ThrowableInformation;
+
+// === Copied from the logback project with permission ==
+public class HardenedLoggingEventInputStream extends HardenedObjectInputStream {
+
+    static final String ARRAY_PREFIX = "[L";
+
+    static public List<String> getWhilelist() {
+
+        List<String> whitelist = new ArrayList<String>();
+        whitelist.add(LoggingEvent.class.getName());
+        whitelist.add(Level.class.getName());
+        whitelist.add(Priority.class.getName());
+        whitelist.add(ThrowableInformation.class.getName());
+        whitelist.add(LocationInfo.class.getName());
+
+        return whitelist;
+    }
+
+    public HardenedLoggingEventInputStream(InputStream is) throws IOException {
+        super(is, getWhilelist());
+    }
+
+    public HardenedLoggingEventInputStream(InputStream is, List<String> additionalAuthorizedClasses) throws IOException {
+        this(is);
+        super.addToWhitelist(additionalAuthorizedClasses);
+    }
+}

src/main/java/org/apache/log4j/net/HardenedObjectInputStream.java

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+/*
+ * 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.log4j.net;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InvalidClassException;
+import java.io.ObjectInputStream;
+import java.io.ObjectStreamClass;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * HardenedObjectInputStream restricts the set of classes that can be
+ * deserialized to a set of explicitly whitelisted classes. This prevents
+ * certain type of attacks from being successful.
+ * 
+ * <p>
+ * It is assumed that classes in the "java.lang" and "java.util" packages are
+ * always authorized.
+ * </p>
+ * 
+ * @author Ceki G&uuml;lc&uuml;
+ * @since 1.2.18
+ * 
+ *  === Copied from the logback project with permission ==
+ */
+public class HardenedObjectInputStream extends ObjectInputStream {
+
+	final List<String> whitelistedClassNames;
+	final static String[] JAVA_PACKAGES = new String[] { "java.lang", "java.util" };
+
+	public HardenedObjectInputStream(InputStream in, String[] whilelist) throws IOException {
+		super(in);
+
+		this.whitelistedClassNames = new ArrayList<String>();
+		if (whilelist != null) {
+			for (int i = 0; i < whilelist.length; i++) {
+				this.whitelistedClassNames.add(whilelist[i]);
+			}
+		}
+	}
+
+	public HardenedObjectInputStream(InputStream in, List<String> whitelist) throws IOException {
+		super(in);
+
+		this.whitelistedClassNames = new ArrayList<String>();
+		this.whitelistedClassNames.addAll(whitelist);
+	}
+
+	@Override
+	protected Class<?> resolveClass(ObjectStreamClass anObjectStreamClass) throws IOException, ClassNotFoundException {
+
+		String incomingClassName = anObjectStreamClass.getName();
+
+		if (!isWhitelisted(incomingClassName)) {
+			throw new InvalidClassException("Unauthorized deserialization attempt", anObjectStreamClass.getName());
+		}
+
+		return super.resolveClass(anObjectStreamClass);
+	}
+
+	private boolean isWhitelisted(String incomingClassName) {
+		for (int i = 0; i < JAVA_PACKAGES.length; i++) {
+			if (incomingClassName.startsWith(JAVA_PACKAGES[i]))
+				return true;
+		}
+		for (String whiteListed : whitelistedClassNames) {
+			if (incomingClassName.equals(whiteListed))
+				return true;
+		}
+		return false;
+	}
+
+	protected void addToWhitelist(List<String> additionalAuthorizedClasses) {
+		whitelistedClassNames.addAll(additionalAuthorizedClasses);
+	}
+}

src/test/java/org/apache/log4j/net/SillySocketClient.java

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+/*
+ * 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.log4j.net;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InterruptedIOException;
+import java.io.ObjectOutputStream;
+import java.net.InetAddress;
+import java.net.Socket;
+import java.net.UnknownHostException;
+import java.util.Properties;
+
+import org.apache.log4j.PropertyConfigurator;
+import org.apache.log4j.helpers.LogLog;
+import org.apache.log4j.spi.ErrorCode;
+
+/**
+ * A silly client used send objects to SocketServer
+ * 
+ * @author ceki
+ *
+ */
+public class SillySocketClient {
+
+	static InetAddress LOCAL_HOST_ADDRESS;
+	static String LOCALHOST_STR;
+
+	static int PORT;
+
+	ObjectOutputStream oos;
+
+	public static void main(String[] args) throws UnknownHostException {
+		Properties props = System.getProperties();
+		for (Object key : props.keySet()) {
+			System.out.println(key + ":" + props.getProperty((String) key));
+		}
+
+		if (args.length == 1)
+			init(args[0]);
+		else {
+			usage("Wrong number of arguments.");
+			return;
+		}
+		LOCAL_HOST_ADDRESS = getAddressByName(LOCALHOST_STR);
+
+		SillySocketClient ssc = new SillySocketClient();
+		ssc.connect(LOCAL_HOST_ADDRESS, PORT);
+
+	}
+
+	static void init(String portStr) {
+		try {
+			PORT = Integer.parseInt(portStr);
+		} catch (java.lang.NumberFormatException e) {
+			e.printStackTrace();
+			usage("Could not interpret port number [" + portStr + "].");
+		}
+	}
+
+	static void usage(String msg) {
+		System.err.println(msg);
+		System.err.println("Usage: java " + SillySocketClient.class.getName() + " port");
+		System.exit(1);
+	}
+
+	static InetAddress getAddressByName(String host) throws java.net.UnknownHostException {
+		return InetAddress.getByName(host);
+	}
+
+	void connect(InetAddress address, int port) {
+		if (address == null)
+			return;
+		try {
+			oos = new ObjectOutputStream(new Socket(address, port).getOutputStream());
+		} catch (IOException e) {
+			if (e instanceof InterruptedIOException) {
+				Thread.currentThread().interrupt();
+			}
+			String msg = "Could not connect to remote log4j server at [" + address.getHostName() + "].";
+			LogLog.error(msg);
+		}
+	}
+
+}