Up-to-date guidelines for serialization-based endpoints

Issue: SPR-15317

spring-web/src/main/java/org/springframework/remoting/httpinvoker/AbstractHttpInvokerRequestExecutor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,14 +43,15 @@ import org.springframework.util.Assert;
  * @since 1.1
  * @see #doExecuteRequest
  */
-public abstract class AbstractHttpInvokerRequestExecutor
-		implements HttpInvokerRequestExecutor, BeanClassLoaderAware {
+public abstract class AbstractHttpInvokerRequestExecutor implements HttpInvokerRequestExecutor, BeanClassLoaderAware {
 
 	/**
 	 * Default content type: "application/x-java-serialized-object"
 	 */
 	public static final String CONTENT_TYPE_SERIALIZED_OBJECT = "application/x-java-serialized-object";
 
+	private static final int SERIALIZED_INVOCATION_BYTE_ARRAY_INITIAL_SIZE = 1024;
+
 
 	protected static final String HTTP_METHOD_POST = "POST";
 
@@ -67,9 +68,6 @@ public abstract class AbstractHttpInvokerRequestExecutor
 	protected static final String ENCODING_GZIP = "gzip";
 
 
-	private static final int SERIALIZED_INVOCATION_BYTE_ARRAY_INITIAL_SIZE = 1024;
-
-
 	protected final Log logger = LogFactory.getLog(getClass());
 
 	private String contentType = CONTENT_TYPE_SERIALIZED_OBJECT;

spring-web/src/main/java/org/springframework/remoting/httpinvoker/HttpInvokerClientInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -46,14 +46,19 @@ import org.springframework.remoting.support.RemoteInvocationResult;
  * a security context). Furthermore, it allows to customize request
  * execution via the {@link HttpInvokerRequestExecutor} strategy.
  *
- * <p>Can use the JDK's {@link java.rmi.server.RMIClassLoader} to load
- * classes from a given {@link #setCodebaseUrl codebase}, performing
- * on-demand dynamic code download from a remote location. The codebase
- * can consist of multiple URLs, separated by spaces. Note that
- * RMIClassLoader requires a SecurityManager to be set, analogous to
- * when using dynamic class download with standard RMI!
+ * <p>Can use the JDK's {@link java.rmi.server.RMIClassLoader} to load classes
+ * from a given {@link #setCodebaseUrl codebase}, performing on-demand dynamic
+ * code download from a remote location. The codebase can consist of multiple
+ * URLs, separated by spaces. Note that RMIClassLoader requires a SecurityManager
+ * to be set, analogous to when using dynamic class download with standard RMI!
  * (See the RMI documentation for details.)
  *
+ * <p><b>WARNING: Be aware of vulnerabilities due to unsafe Java deserialization:
+ * Manipulated input streams could lead to unwanted code execution on the server
+ * during the deserialization step. As a consequence, do not expose HTTP invoker
+ * endpoints to untrusted clients but rather just between your own services.</b>
+ * In general, we strongly recommend any other message format (e.g. JSON) instead.
+ *
  * @author Juergen Hoeller
  * @since 1.1
  * @see #setServiceUrl

spring-web/src/main/java/org/springframework/remoting/httpinvoker/HttpInvokerProxyFactoryBean.java

@@ -40,6 +40,7 @@ import org.springframework.beans.factory.FactoryBean;
  * Manipulated input streams could lead to unwanted code execution on the server
  * during the deserialization step. As a consequence, do not expose HTTP invoker
  * endpoints to untrusted clients but rather just between your own services.</b>
+ * In general, we strongly recommend any other message format (e.g. JSON) instead.
  *
  * @author Juergen Hoeller
  * @since 1.1
@@ -51,8 +52,7 @@ import org.springframework.beans.factory.FactoryBean;
  * @see org.springframework.remoting.rmi.RmiProxyFactoryBean
  * @see org.springframework.remoting.caucho.HessianProxyFactoryBean
  */
-public class HttpInvokerProxyFactoryBean extends HttpInvokerClientInterceptor
-		implements FactoryBean<Object> {
+public class HttpInvokerProxyFactoryBean extends HttpInvokerClientInterceptor implements FactoryBean<Object> {
 
 	private Object serviceProxy;
 

spring-web/src/main/java/org/springframework/remoting/httpinvoker/HttpInvokerServiceExporter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -52,6 +52,7 @@ import org.springframework.web.util.NestedServletException;
  * Manipulated input streams could lead to unwanted code execution on the server
  * during the deserialization step. As a consequence, do not expose HTTP invoker
  * endpoints to untrusted clients but rather just between your own services.</b>
+ * In general, we strongly recommend any other message format (e.g. JSON) instead.
  *
  * @author Juergen Hoeller
  * @since 1.1
@@ -60,8 +61,7 @@ import org.springframework.web.util.NestedServletException;
  * @see org.springframework.remoting.rmi.RmiServiceExporter
  * @see org.springframework.remoting.caucho.HessianServiceExporter
  */
-public class HttpInvokerServiceExporter extends RemoteInvocationSerializingExporter
-		implements HttpRequestHandler {
+public class HttpInvokerServiceExporter extends RemoteInvocationSerializingExporter implements HttpRequestHandler {
 
 	/**
 	 * Reads a remote invocation from the request, executes it,
@@ -86,10 +86,8 @@ public class HttpInvokerServiceExporter extends RemoteInvocationSerializingExpor
 
 	/**
 	 * Read a RemoteInvocation from the given HTTP request.
-	 * <p>Delegates to
-	 * {@link #readRemoteInvocation(javax.servlet.http.HttpServletRequest, java.io.InputStream)}
-	 * with the
-	 * {@link javax.servlet.ServletRequest#getInputStream() servlet request's input stream}.
+	 * <p>Delegates to {@link #readRemoteInvocation(HttpServletRequest, InputStream)} with
+	 * the {@link HttpServletRequest#getInputStream() servlet request's input stream}.
 	 * @param request current HTTP request
 	 * @return the RemoteInvocation object
 	 * @throws IOException in case of I/O failure
@@ -205,12 +203,10 @@ public class HttpInvokerServiceExporter extends RemoteInvocationSerializingExpor
 	/**
 	 * Decorate an {@code OutputStream} to guard against {@code flush()} calls,
 	 * which are turned into no-ops.
-	 *
 	 * <p>Because {@link ObjectOutputStream#close()} will in fact flush/drain
 	 * the underlying stream twice, this {@link FilterOutputStream} will
 	 * guard against individual flush calls. Multiple flush calls can lead
 	 * to performance issues, since writes aren't gathered as they should be.
-	 *
 	 * @see <a href="https://jira.spring.io/browse/SPR-14040">SPR-14040</a>
 	 */
 	private static class FlushGuardedOutputStream extends FilterOutputStream {

spring-web/src/main/java/org/springframework/remoting/httpinvoker/SimpleHttpInvokerServiceExporter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -45,6 +45,12 @@ import org.springframework.remoting.support.RemoteInvocationResult;
  * being tied to Java. Nevertheless, it is as easy to set up as Hessian,
  * which is its main advantage compared to RMI.
  *
+ * <p><b>WARNING: Be aware of vulnerabilities due to unsafe Java deserialization:
+ * Manipulated input streams could lead to unwanted code execution on the server
+ * during the deserialization step. As a consequence, do not expose HTTP invoker
+ * endpoints to untrusted clients but rather just between your own services.</b>
+ * In general, we strongly recommend any other message format (e.g. JSON) instead.
+ *
  * @author Juergen Hoeller
  * @since 2.5.1
  * @see org.springframework.remoting.httpinvoker.HttpInvokerClientInterceptor
@@ -52,15 +58,14 @@ import org.springframework.remoting.support.RemoteInvocationResult;
  * @see org.springframework.remoting.caucho.SimpleHessianServiceExporter
  */
 @UsesSunHttpServer
-public class SimpleHttpInvokerServiceExporter extends RemoteInvocationSerializingExporter
-		implements HttpHandler {
+public class SimpleHttpInvokerServiceExporter extends RemoteInvocationSerializingExporter implements HttpHandler {
 
 	/**
 	 * Reads a remote invocation from the request, executes it,
 	 * and writes the remote invocation result to the response.
-	 * @see #readRemoteInvocation(com.sun.net.httpserver.HttpExchange)
-	 * @see #invokeAndCreateResult(org.springframework.remoting.support.RemoteInvocation, Object)
-	 * @see #writeRemoteInvocationResult(com.sun.net.httpserver.HttpExchange, org.springframework.remoting.support.RemoteInvocationResult)
+	 * @see #readRemoteInvocation(HttpExchange)
+	 * @see #invokeAndCreateResult(RemoteInvocation, Object)
+	 * @see #writeRemoteInvocationResult(HttpExchange, RemoteInvocationResult)
 	 */
 	@Override
 	public void handle(HttpExchange exchange) throws IOException {
@@ -78,10 +83,8 @@ public class SimpleHttpInvokerServiceExporter extends RemoteInvocationSerializin
 
 	/**
 	 * Read a RemoteInvocation from the given HTTP request.
-	 * <p>Delegates to
-	 * {@link #readRemoteInvocation(com.sun.net.httpserver.HttpExchange, java.io.InputStream)}
-	 * with the
-	 * {@link com.sun.net.httpserver.HttpExchange#getRequestBody()} request's input stream}.
+	 * <p>Delegates to {@link #readRemoteInvocation(HttpExchange, InputStream)}
+	 * with the {@link HttpExchange#getRequestBody()} request's input stream}.
 	 * @param exchange current HTTP request/response
 	 * @return the RemoteInvocation object
 	 * @throws java.io.IOException in case of I/O failure

src/asciidoc/data-access.adoc

@@ -6651,13 +6651,13 @@ which consists of string aliases mapped to classes:
 
 [WARNING]
 ====
-
-By default, XStream allows for arbitrary classes to be unmarshalled, which can result in
-security vulnerabilities. As such, it is __not recommended to use the
+By default, XStream allows for arbitrary classes to be unmarshalled, which can lead to
+unsafe Java serialization effects. As such, it is __not recommended to use the
 `XStreamMarshaller` to unmarshal XML from external sources__ (i.e. the Web), as this can
-result in __security vulnerabilities__. If you do use the `XStreamMarshaller` to
-unmarshal XML from an external source, set the `supportedClasses` property on the
-`XStreamMarshaller`, like so:
+result in __security vulnerabilities__.
+
+If you choose to use the `XStreamMarshaller` to unmarshal XML from an external source,
+set the `supportedClasses` property on the `XStreamMarshaller`, like as follows:
 
 [source,xml,indent=0]
 [subs="verbatim,quotes"]

src/asciidoc/integration.adoc

@@ -377,6 +377,21 @@ advanced and easier-to-use functionality. Refer to
 http://hc.apache.org/httpcomponents-client-ga/[hc.apache.org/httpcomponents-client-ga/]
 for more information.
 
+[WARNING]
+====
+Be aware of vulnerabilities due to unsafe Java deserialization:
+Manipulated input streams could lead to unwanted code execution on the server
+during the deserialization step. As a consequence, do not expose HTTP invoker
+endpoints to untrusted clients but rather just between your own services.
+In general, we strongly recommend any other message format (e.g. JSON) instead.
+
+If you are concerned about security vulnerabilities due to Java serialization,
+consider the general-purpose serialization filter mechanism at the core JVM level,
+originally developed for JDK 9 but backported to JDK 8, 7 and 6 in the meantime:
+https://blogs.oracle.com/java-platform-group/entry/incoming_filter_serialization_data_a
+http://openjdk.java.net/jeps/290
+====
+
 
 
 [[remoting-httpinvoker-server]]
@@ -2499,7 +2514,7 @@ be obtained from JNDI instead (using `<jee:jndi-lookup>`). The Spring-based mess
 listeners can then interact with the server-hosted `ResourceAdapter`, also using the
 server's built-in `WorkManager`.
 
-Please consult the JavaDoc for `JmsMessageEndpointManager`, `JmsActivationSpecConfig`,
+Please consult the javadoc for `JmsMessageEndpointManager`, `JmsActivationSpecConfig`,
 and `ResourceAdapterFactoryBean` for more details.
 
 Spring also provides a generic JCA message endpoint manager which is not tied to JMS:
@@ -2507,7 +2522,7 @@ Spring also provides a generic JCA message endpoint manager which is not tied to
 for using any message listener type (e.g. a CCI MessageListener) and any
 provider-specific ActivationSpec object. Check out your JCA provider's documentation to
 find out about the actual capabilities of your connector, and consult
-`GenericMessageEndpointManager`'s JavaDoc for the Spring-specific configuration details.
+`GenericMessageEndpointManager`'s javadoc for the Spring-specific configuration details.
 
 [NOTE]
 ====
@@ -5966,7 +5981,6 @@ along with an inline image.
 
 [WARNING]
 ====
-
 Inline resources are added to the mime message using the specified `Content-ID` (
 `identifier1234` in the above example). The order in which you are adding the text and
 the resource are __very__ important. Be sure to __first add the text__ and after that