Add processExternalEntities support to OXM

Update OXM AbstractMarshaller to support processing of external
XML entities. By default external entities will not be processed.

Issue: SPR-11376

Author: rstoyanchev

spring-oxm/src/main/java/org/springframework/oxm/castor/CastorMarshaller.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -162,6 +162,11 @@ public void setEncoding(String encoding) {
 		this.encoding = encoding;
 	}
 
+	@Override
+	protected String getDefaultEncoding() {
+		return this.encoding;
+	}
+
 	/**
 	 * Set the locations of the Castor XML mapping files.
 	 */
@@ -604,7 +609,7 @@ protected final Object unmarshalReader(Reader reader) throws XmlMappingException
 	}
 
 	@Override
-	protected final Object unmarshalSaxReader(XMLReader xmlReader, InputSource inputSource)
+	protected Object unmarshalSaxReader(XMLReader xmlReader, InputSource inputSource)
 			throws XmlMappingException, IOException {
 
 		UnmarshalHandler unmarshalHandler = createUnmarshaller().createHandler();

spring-oxm/src/main/java/org/springframework/oxm/jaxb/Jaxb2Marshaller.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -401,6 +401,13 @@ public void setProcessExternalEntities(boolean processExternalEntities) {
 		this.processExternalEntities = processExternalEntities;
 	}
 
+	/**
+	 * @return the configured value for whether XML external entities are allowed.
+	 */
+	public boolean isProcessExternalEntities() {
+		return this.processExternalEntities;
+	}
+
 	@Override
 	public void setBeanClassLoader(ClassLoader classLoader) {
 		this.beanClassLoader = classLoader;

spring-oxm/src/main/java/org/springframework/oxm/jibx/JibxMarshaller.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -28,6 +28,7 @@
 import javax.xml.stream.XMLStreamException;
 import javax.xml.stream.XMLStreamReader;
 import javax.xml.stream.XMLStreamWriter;
+import javax.xml.transform.OutputKeys;
 import javax.xml.transform.Result;
 import javax.xml.transform.Source;
 import javax.xml.transform.Transformer;
@@ -148,6 +149,11 @@ public void setEncoding(String encoding) {
 		this.encoding = encoding;
 	}
 
+	@Override
+	protected String getDefaultEncoding() {
+		return this.encoding;
+	}
+
 	/**
 	 * Set the document standalone flag for marshalling. By default, this flag is not present.
 	 */
@@ -389,13 +395,12 @@ protected Object unmarshalReader(Reader reader) throws XmlMappingException, IOEx
 		}
 	}
 
-
 	// Unsupported Unmarshalling
 
 	@Override
 	protected Object unmarshalDomNode(Node node) throws XmlMappingException {
 		try {
-			return transformAndUnmarshal(new DOMSource(node));
+			return transformAndUnmarshal(new DOMSource(node), null);
 		}
 		catch (IOException ex) {
 			throw new UnmarshallingFailureException("JiBX unmarshalling exception", ex);
@@ -406,20 +411,23 @@ protected Object unmarshalDomNode(Node node) throws XmlMappingException {
 	protected Object unmarshalSaxReader(XMLReader xmlReader, InputSource inputSource)
 			throws XmlMappingException, IOException {
 
-		return transformAndUnmarshal(new SAXSource(xmlReader, inputSource));
+		return transformAndUnmarshal(new SAXSource(xmlReader, inputSource), inputSource.getEncoding());
 	}
 
-	private Object transformAndUnmarshal(Source source) throws IOException {
+	private Object transformAndUnmarshal(Source source, String encoding) throws IOException {
 		try {
 			Transformer transformer = this.transformerFactory.newTransformer();
+			if (encoding != null) {
+				transformer.setOutputProperty(OutputKeys.ENCODING, encoding);
+			}
 			ByteArrayOutputStream os = new ByteArrayOutputStream();
 			transformer.transform(source, new StreamResult(os));
 			ByteArrayInputStream is = new ByteArrayInputStream(os.toByteArray());
 			return unmarshalInputStream(is);
 		}
 		catch (TransformerException ex) {
 			throw new MarshallingFailureException(
-					"Could not transform from [" + ClassUtils.getShortName(source.getClass()) + "]");
+					"Could not transform from [" + ClassUtils.getShortName(source.getClass()) + "]", ex);
 		}
 	}
 

spring-oxm/src/main/java/org/springframework/oxm/support/AbstractMarshaller.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -73,6 +73,33 @@ public abstract class AbstractMarshaller implements Marshaller, Unmarshaller {
 
 	private final Object documentBuilderFactoryMonitor = new Object();
 
+	private boolean processExternalEntities = false;
+
+
+	/**
+	 * Indicates whether external XML entities are processed when unmarshalling.
+	 * <p>Default is {@code false}, meaning that external entities are not resolved.
+	 * Note that processing of external entities will only be enabled/disabled when the
+	 * {@code Source} passed to {@link #unmarshal(Source)} is a {@link SAXSource} or
+	 * {@link StreamSource}. It has no effect for {@link DOMSource} or {@link StAXSource}
+	 * instances.
+	 */
+	public void setProcessExternalEntities(boolean processExternalEntities) {
+		this.processExternalEntities = processExternalEntities;
+	}
+
+	/**
+	 * @return the configured value for whether XML external entities are allowed.
+	 */
+	public boolean isProcessExternalEntities() {
+		return this.processExternalEntities;
+	}
+
+	/**
+	 * @return the default encoding to use for marshalling or unmarshalling from
+	 * 	a byte stream, or {@code null}.
+	 */
+	abstract protected String getDefaultEncoding();
 
 	/**
 	 * Marshals the object graph with the given root into the provided {@code javax.xml.transform.Result}.
@@ -131,7 +158,7 @@ else if (source instanceof SAXSource) {
 			return unmarshalSaxSource((SAXSource) source);
 		}
 		else if (source instanceof StreamSource) {
-			return unmarshalStreamSource((StreamSource) source);
+			return unmarshalStreamSourceNoExternalEntitities((StreamSource) source);
 		}
 		else {
 			throw new IllegalArgumentException("Unknown Source type: " + source.getClass());
@@ -173,7 +200,9 @@ protected DocumentBuilderFactory createDocumentBuilderFactory() throws ParserCon
 	 * @throws SAXException if thrown by JAXP methods
 	 */
 	protected XMLReader createXmlReader() throws SAXException {
-		return XMLReaderFactory.createXMLReader();
+		XMLReader xmlReader = XMLReaderFactory.createXMLReader();
+		xmlReader.setFeature("http://xml.org/sax/features/external-general-entities", isProcessExternalEntities());
+		return xmlReader;
 	}
 
 
@@ -355,9 +384,44 @@ protected Object unmarshalSaxSource(SAXSource saxSource) throws XmlMappingExcept
 		return unmarshalSaxReader(saxSource.getXMLReader(), saxSource.getInputSource());
 	}
 
+	/**
+	 * Template method for handling {@code StreamSource}s with protection against
+	 * the XML External Entity (XXE) processing vulnerability taking into account
+	 * the value of the {@link #setProcessExternalEntities(boolean)} property.
+	 * <p>
+	 * The default implementation wraps the StreamSource as a SAXSource and delegates
+	 * to {@link #unmarshalSaxSource(javax.xml.transform.sax.SAXSource)}.
+	 *
+	 * @param streamSource the {@code StreamSource}
+	 * @return the object graph
+	 * @throws IOException if an I/O exception occurs
+	 * @throws XmlMappingException if the given source cannot be mapped to an object
+	 *
+	 * @see <a href="https://www.owasp.org/index.php/XML_External_Entity_(XXE)_Processing">XML_External_Entity_(XXE)_Processing</a>
+	 */
+	protected Object unmarshalStreamSourceNoExternalEntitities(StreamSource streamSource)
+			throws XmlMappingException, IOException {
+
+		InputSource inputSource;
+		if (streamSource.getInputStream() != null) {
+			inputSource = new InputSource(streamSource.getInputStream());
+			inputSource.setEncoding(getDefaultEncoding());
+		}
+		else if (streamSource.getReader() != null) {
+			inputSource = new InputSource(streamSource.getReader());
+		}
+		else {
+			inputSource = new InputSource(streamSource.getSystemId());
+		}
+		return unmarshalSaxSource(new SAXSource(inputSource));
+	}
+
 	/**
 	 * Template method for handling {@code StreamSource}s.
-	 * <p>This implementation defers to {@code unmarshalInputStream} or {@code unmarshalReader}.
+	 * <p>As of 3.2.8 and 4.0.2 this method is no longer invoked from
+	 * {@link #unmarshal(javax.xml.transform.Source)}. The method invoked instead is
+	 * {@link #unmarshalStreamSourceNoExternalEntitities(javax.xml.transform.stream.StreamSource)}.
+	 *
 	 * @param streamSource the {@code StreamSource}
 	 * @return the object graph
 	 * @throws IOException if an I/O exception occurs

spring-oxm/src/main/java/org/springframework/oxm/xmlbeans/XmlBeansMarshaller.java

@@ -113,6 +113,10 @@ public boolean isValidating() {
 		return this.validating;
 	}
 
+	@Override
+	protected String getDefaultEncoding() {
+		return null;
+	}
 
 	/**
 	 * This implementation returns true if the given class is an implementation of {@link XmlObject}.

spring-oxm/src/main/java/org/springframework/oxm/xstream/XStreamMarshaller.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -31,6 +31,7 @@
 import javax.xml.stream.XMLStreamException;
 import javax.xml.stream.XMLStreamReader;
 import javax.xml.stream.XMLStreamWriter;
+import javax.xml.transform.stream.StreamSource;
 
 import com.thoughtworks.xstream.XStream;
 import com.thoughtworks.xstream.converters.ConversionException;
@@ -353,6 +354,11 @@ public void setEncoding(String encoding) {
 		this.encoding = encoding;
 	}
 
+	@Override
+	protected String getDefaultEncoding() {
+		return this.encoding;
+	}
+
 	/**
 	 * Set the classes supported by this marshaller.
 	 * <p>If this property is empty (the default), all classes are supported.
@@ -482,6 +488,11 @@ private void marshal(Object graph, HierarchicalStreamWriter streamWriter) {
 
 	// Unmarshalling
 
+	@Override
+	protected Object unmarshalStreamSourceNoExternalEntitities(StreamSource streamSource) throws XmlMappingException, IOException {
+		return super.unmarshalStreamSource(streamSource);
+	}
+
 	@Override
 	protected Object unmarshalDomNode(Node node) throws XmlMappingException {
 		HierarchicalStreamReader streamReader;

spring-oxm/src/test/java/org/springframework/oxm/castor/CastorUnmarshallerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -19,6 +19,8 @@
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.StringReader;
+import java.util.concurrent.atomic.AtomicReference;
+import javax.xml.transform.sax.SAXSource;
 import javax.xml.transform.stream.StreamSource;
 
 import org.junit.Ignore;
@@ -28,6 +30,8 @@
 import org.springframework.oxm.AbstractUnmarshallerTests;
 import org.springframework.oxm.MarshallingException;
 import org.springframework.oxm.Unmarshaller;
+import org.xml.sax.InputSource;
+import org.xml.sax.XMLReader;
 
 import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
@@ -203,4 +207,59 @@ private Object unmarshal(String xml) throws Exception {
 		StreamSource source = new StreamSource(new StringReader(xml));
 		return unmarshaller.unmarshal(source);
 	}
+
+	@Test
+	public void unmarshalStreamSourceExternalEntities() throws Exception {
+
+		final AtomicReference<XMLReader> result = new AtomicReference<XMLReader>();
+		CastorMarshaller marshaller = new CastorMarshaller() {
+			@Override
+			protected Object unmarshalSaxReader(XMLReader xmlReader, InputSource inputSource) {
+				result.set(xmlReader);
+				return null;
+			}
+		};
+
+		// 1. external-general-entities disabled (default)
+
+		marshaller.unmarshal(new StreamSource("1"));
+		assertNotNull(result.get());
+		assertEquals(false, result.get().getFeature("http://xml.org/sax/features/external-general-entities"));
+
+		// 2. external-general-entities disabled (default)
+
+		result.set(null);
+		marshaller.setProcessExternalEntities(true);
+		marshaller.unmarshal(new StreamSource("1"));
+		assertNotNull(result.get());
+		assertEquals(true, result.get().getFeature("http://xml.org/sax/features/external-general-entities"));
+	}
+
+	@Test
+	public void unmarshalSaxSourceExternalEntities() throws Exception {
+
+		final AtomicReference<XMLReader> result = new AtomicReference<XMLReader>();
+		CastorMarshaller marshaller = new CastorMarshaller() {
+			@Override
+			protected Object unmarshalSaxReader(XMLReader xmlReader, InputSource inputSource) {
+				result.set(xmlReader);
+				return null;
+			}
+		};
+
+		// 1. external-general-entities disabled (default)
+
+		marshaller.unmarshal(new SAXSource(new InputSource("1")));
+		assertNotNull(result.get());
+		assertEquals(false, result.get().getFeature("http://xml.org/sax/features/external-general-entities"));
+
+		// 2. external-general-entities disabled (default)
+
+		result.set(null);
+		marshaller.setProcessExternalEntities(true);
+		marshaller.unmarshal(new SAXSource(new InputSource("1")));
+		assertNotNull(result.get());
+		assertEquals(true, result.get().getFeature("http://xml.org/sax/features/external-general-entities"));
+	}
+
 }