Merge pull request from GHSA-37xm-4h3m-5w3v

* refactor: Clean up whitespace in existing PgSQLXMLTest

* fix: Fix XXE vulnerability in PgSQLXML by disabling external access and doctypes

Fixes XXE vulnerability by defaulting to disabling external access and doc types. The
legacy insecure behavior can be restored via the new connection property xmlFactoryFactory
with a value of LEGACY_INSECURE. Alternatively, a custom class name can be specified that
implements org.postgresql.xml.PGXmlFactoryFactory and takes a no argument constructor.

* fix: Add missing getter and setter for XML_FACTORY_FACTORY to BasicDataSource

pgjdbc/src/main/java/org/postgresql/PGProperty.java

@@ -661,6 +661,17 @@ public enum PGProperty {
     "false",
     "Use SPNEGO in SSPI authentication requests"),
 
+  /**
+   * Factory class to instantiate factories for XML processing.
+   * The default factory disables external entity processing.
+   * Legacy behavior with external entity processing can be enabled by specifying a value of LEGACY_INSECURE.
+   * Or specify a custom class that implements {@code org.postgresql.xml.PGXmlFactoryFactory}.
+   */
+  XML_FACTORY_FACTORY(
+    "xmlFactoryFactory",
+    "",
+    "Factory class to instantiate factories for XML processing"),
+
   ;
 
   private final String name;

pgjdbc/src/main/java/org/postgresql/core/BaseConnection.java

@@ -10,6 +10,7 @@
 import org.postgresql.jdbc.FieldMetadata;
 import org.postgresql.jdbc.TimestampUtils;
 import org.postgresql.util.LruCache;
+import org.postgresql.xml.PGXmlFactoryFactory;
 
 import java.sql.Connection;
 import java.sql.ResultSet;
@@ -212,4 +213,12 @@ CachedQuery createQuery(String sql, boolean escapeProcessing, boolean isParamete
    * @see PGProperty#READ_ONLY_MODE
    */
   boolean hintReadOnly();
+
+  /**
+   * Retrieve the factory to instantiate XML processing factories.
+   *
+   * @return The factory to use to instantiate XML processing factories
+   * @throws SQLException if the class cannot be found or instantiated.
+   */
+  PGXmlFactoryFactory getXmlFactoryFactory() throws SQLException;
 }

pgjdbc/src/main/java/org/postgresql/ds/common/BaseDataSource.java

@@ -1526,6 +1526,14 @@ public java.util.logging.Logger getParentLogger() {
     return Logger.getLogger("org.postgresql");
   }
 
+  public String getXmlFactoryFactory() {
+    return PGProperty.XML_FACTORY_FACTORY.get(properties);
+  }
+
+  public void setXmlFactoryFactory(String xmlFactoryFactory) {
+    PGProperty.XML_FACTORY_FACTORY.set(properties, xmlFactoryFactory);
+  }
+
   /*
    * Alias methods below, these are to help with ease-of-use with other database tools / frameworks
    * which expect normal java bean getters / setters to exist for the property names.

pgjdbc/src/main/java/org/postgresql/jdbc/PgConnection.java

@@ -37,6 +37,9 @@
 import org.postgresql.util.PGobject;
 import org.postgresql.util.PSQLException;
 import org.postgresql.util.PSQLState;
+import org.postgresql.xml.DefaultPGXmlFactoryFactory;
+import org.postgresql.xml.LegacyInsecurePGXmlFactoryFactory;
+import org.postgresql.xml.PGXmlFactoryFactory;
 
 import java.io.IOException;
 import java.sql.Array;
@@ -156,6 +159,9 @@ private enum ReadOnlyBehavior {
 
   private final LruCache<FieldMetadata.Key, FieldMetadata> fieldMetadataCache;
 
+  private final String xmlFactoryFactoryClass;
+  private PGXmlFactoryFactory xmlFactoryFactory;
+
   final CachedQuery borrowQuery(String sql) throws SQLException {
     return queryExecutor.borrowQuery(sql);
   }
@@ -311,6 +317,8 @@ public TimeZone get() {
         false);
 
     replicationConnection = PGProperty.REPLICATION.get(info) != null;
+
+    xmlFactoryFactoryClass = PGProperty.XML_FACTORY_FACTORY.get(info);
   }
 
   private static ReadOnlyBehavior getReadOnlyBehavior(String property) {
@@ -1823,4 +1831,36 @@ public final String getParameterStatus(String parameterName) {
     return queryExecutor.getParameterStatus(parameterName);
   }
 
+  @Override
+  public PGXmlFactoryFactory getXmlFactoryFactory() throws SQLException {
+    if (xmlFactoryFactory == null) {
+      if (xmlFactoryFactoryClass == null || xmlFactoryFactoryClass.equals("")) {
+        xmlFactoryFactory = DefaultPGXmlFactoryFactory.INSTANCE;
+      } else if (xmlFactoryFactoryClass.equals("LEGACY_INSECURE")) {
+        xmlFactoryFactory = LegacyInsecurePGXmlFactoryFactory.INSTANCE;
+      } else {
+        Class<?> clazz;
+        try {
+          clazz = Class.forName(xmlFactoryFactoryClass);
+        } catch (ClassNotFoundException ex) {
+          throw new PSQLException(
+              GT.tr("Could not instantiate xmlFactoryFactory: {0}", xmlFactoryFactoryClass),
+              PSQLState.INVALID_PARAMETER_VALUE, ex);
+        }
+        if (!clazz.isAssignableFrom(PGXmlFactoryFactory.class)) {
+          throw new PSQLException(
+              GT.tr("Connection property xmlFactoryFactory must implement PGXmlFactoryFactory: {0}", xmlFactoryFactoryClass),
+              PSQLState.INVALID_PARAMETER_VALUE);
+        }
+        try {
+          xmlFactoryFactory = (PGXmlFactoryFactory) clazz.newInstance();
+        } catch (Exception ex) {
+          throw new PSQLException(
+              GT.tr("Could not instantiate xmlFactoryFactory: {0}", xmlFactoryFactoryClass),
+              PSQLState.INVALID_PARAMETER_VALUE, ex);
+        }
+      }
+    }
+    return xmlFactoryFactory;
+  }
 }

pgjdbc/src/main/java/org/postgresql/jdbc/PgSQLXML.java

@@ -9,10 +9,11 @@
 import org.postgresql.util.GT;
 import org.postgresql.util.PSQLException;
 import org.postgresql.util.PSQLState;
+import org.postgresql.xml.DefaultPGXmlFactoryFactory;
+import org.postgresql.xml.PGXmlFactoryFactory;
 
-import org.xml.sax.ErrorHandler;
 import org.xml.sax.InputSource;
-import org.xml.sax.SAXParseException;
+import org.xml.sax.XMLReader;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
@@ -27,7 +28,6 @@
 import java.sql.SQLXML;
 
 import javax.xml.parsers.DocumentBuilder;
-import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.stream.XMLInputFactory;
 import javax.xml.stream.XMLOutputFactory;
 import javax.xml.stream.XMLStreamException;
@@ -77,6 +77,13 @@ private PgSQLXML(BaseConnection conn, String data, boolean initialized) {
     this.freed = false;
   }
 
+  private PGXmlFactoryFactory getXmlFactoryFactory() throws SQLException {
+    if (conn != null) {
+      return conn.getXmlFactoryFactory();
+    }
+    return DefaultPGXmlFactoryFactory.INSTANCE;
+  }
+
   @Override
   public synchronized void free() {
     freed = true;
@@ -132,18 +139,17 @@ public synchronized <T extends Source> T getSource(Class<T> sourceClass) throws
 
     try {
       if (sourceClass == null || DOMSource.class.equals(sourceClass)) {
-        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
-        DocumentBuilder builder = factory.newDocumentBuilder();
-        builder.setErrorHandler(new NonPrintingErrorHandler());
+        DocumentBuilder builder = getXmlFactoryFactory().newDocumentBuilder();
         InputSource input = new InputSource(new StringReader(data));
         return (T) new DOMSource(builder.parse(input));
       } else if (SAXSource.class.equals(sourceClass)) {
+        XMLReader reader = getXmlFactoryFactory().createXMLReader();
         InputSource is = new InputSource(new StringReader(data));
-        return (T) new SAXSource(is);
+        return (T) new SAXSource(reader, is);
       } else if (StreamSource.class.equals(sourceClass)) {
         return (T) new StreamSource(new StringReader(data));
       } else if (StAXSource.class.equals(sourceClass)) {
-        XMLInputFactory xif = XMLInputFactory.newInstance();
+        XMLInputFactory xif = getXmlFactoryFactory().newXMLInputFactory();
         XMLStreamReader xsr = xif.createXMLStreamReader(new StringReader(data));
         return (T) new StAXSource(xsr);
       }
@@ -191,8 +197,7 @@ public synchronized <T extends Result> T setResult(Class<T> resultClass) throws
       return (T) domResult;
     } else if (SAXResult.class.equals(resultClass)) {
       try {
-        SAXTransformerFactory transformerFactory =
-            (SAXTransformerFactory) SAXTransformerFactory.newInstance();
+        SAXTransformerFactory transformerFactory = getXmlFactoryFactory().newSAXTransformerFactory();
         TransformerHandler transformerHandler = transformerFactory.newTransformerHandler();
         stringWriter = new StringWriter();
         transformerHandler.setResult(new StreamResult(stringWriter));
@@ -209,7 +214,7 @@ public synchronized <T extends Result> T setResult(Class<T> resultClass) throws
     } else if (StAXResult.class.equals(resultClass)) {
       stringWriter = new StringWriter();
       try {
-        XMLOutputFactory xof = XMLOutputFactory.newInstance();
+        XMLOutputFactory xof = getXmlFactoryFactory().newXMLOutputFactory();
         XMLStreamWriter xsw = xof.createXMLStreamWriter(stringWriter);
         active = true;
         return (T) new StAXResult(xsw);
@@ -272,7 +277,7 @@ private void ensureInitialized() throws SQLException {
       // and use the identify transform to get it into a
       // friendlier result format.
       try {
-        TransformerFactory factory = TransformerFactory.newInstance();
+        TransformerFactory factory = getXmlFactoryFactory().newTransformerFactory();
         Transformer transformer = factory.newTransformer();
         DOMSource domSource = new DOMSource(domResult.getNode());
         StringWriter stringWriter = new StringWriter();
@@ -298,18 +303,4 @@ private void initialize() throws SQLException {
     }
     initialized = true;
   }
-
-  // Don't clutter System.err with errors the user can't silence.
-  // If something bad really happens an exception will be thrown.
-  static class NonPrintingErrorHandler implements ErrorHandler {
-    public void error(SAXParseException e) {
-    }
-
-    public void fatalError(SAXParseException e) {
-    }
-
-    public void warning(SAXParseException e) {
-    }
-  }
-
 }

pgjdbc/src/main/java/org/postgresql/xml/DefaultPGXmlFactoryFactory.java

@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ * See the LICENSE file in the project root for more information.
+ */
+
+package org.postgresql.xml;
+
+import org.xml.sax.SAXException;
+import org.xml.sax.XMLReader;
+import org.xml.sax.helpers.XMLReaderFactory;
+
+import javax.xml.XMLConstants;
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.stream.XMLInputFactory;
+import javax.xml.stream.XMLOutputFactory;
+import javax.xml.transform.TransformerFactory;
+import javax.xml.transform.sax.SAXTransformerFactory;
+
+/**
+ * Default implementation of PGXmlFactoryFactory that configures each factory per OWASP recommendations.
+ *
+ * @see <a href="https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html">https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html</a>
+ */
+public class DefaultPGXmlFactoryFactory implements PGXmlFactoryFactory {
+  public static final DefaultPGXmlFactoryFactory INSTANCE = new DefaultPGXmlFactoryFactory();
+
+  private DefaultPGXmlFactoryFactory() {
+  }
+
+  private DocumentBuilderFactory getDocumentBuilderFactory() {
+    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+    setFactoryProperties(factory);
+    factory.setXIncludeAware(false);
+    factory.setExpandEntityReferences(false);
+    return factory;
+  }
+
+  @Override
+  public DocumentBuilder newDocumentBuilder() throws ParserConfigurationException {
+    DocumentBuilder builder = getDocumentBuilderFactory().newDocumentBuilder();
+    builder.setEntityResolver(EmptyStringEntityResolver.INSTANCE);
+    builder.setErrorHandler(NullErrorHandler.INSTANCE);
+    return builder;
+  }
+
+  @Override
+  public TransformerFactory newTransformerFactory() {
+    TransformerFactory factory = TransformerFactory.newInstance();
+    setFactoryProperties(factory);
+    return factory;
+  }
+
+  @Override
+  public SAXTransformerFactory newSAXTransformerFactory() {
+    SAXTransformerFactory factory = (SAXTransformerFactory) SAXTransformerFactory.newInstance();
+    setFactoryProperties(factory);
+    return factory;
+  }
+
+  @Override
+  public XMLInputFactory newXMLInputFactory() {
+    XMLInputFactory factory = XMLInputFactory.newInstance();
+    setPropertyQuietly(factory, XMLInputFactory.SUPPORT_DTD, false);
+    setPropertyQuietly(factory, XMLInputFactory.IS_SUPPORTING_EXTERNAL_ENTITIES, false);
+    return factory;
+  }
+
+  @Override
+  public XMLOutputFactory newXMLOutputFactory() {
+    XMLOutputFactory factory = XMLOutputFactory.newInstance();
+    return factory;
+  }
+
+  @Override
+  public XMLReader createXMLReader() throws SAXException {
+    XMLReader factory = XMLReaderFactory.createXMLReader();
+    setFeatureQuietly(factory, "http://apache.org/xml/features/disallow-doctype-decl", true);
+    setFeatureQuietly(factory, "http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
+    setFeatureQuietly(factory, "http://xml.org/sax/features/external-general-entities", false);
+    setFeatureQuietly(factory, "http://xml.org/sax/features/external-parameter-entities", false);
+    factory.setErrorHandler(NullErrorHandler.INSTANCE);
+    return factory;
+  }
+
+  private static void setFeatureQuietly(Object factory, String name, boolean value) {
+    try {
+      if (factory instanceof DocumentBuilderFactory) {
+        ((DocumentBuilderFactory) factory).setFeature(name, value);
+      } else if (factory instanceof TransformerFactory) {
+        ((TransformerFactory) factory).setFeature(name, value);
+      } else if (factory instanceof XMLReader) {
+        ((XMLReader) factory).setFeature(name, value);
+      } else {
+        throw new Error("Invalid factory class: " + factory.getClass());
+      }
+      return;
+    } catch (Exception ignore) {
+    }
+  }
+
+  private static void setAttributeQuietly(Object factory, String name, Object value) {
+    try {
+      if (factory instanceof DocumentBuilderFactory) {
+        ((DocumentBuilderFactory) factory).setAttribute(name, value);
+      } else if (factory instanceof TransformerFactory) {
+        ((TransformerFactory) factory).setAttribute(name, value);
+      } else {
+        throw new Error("Invalid factory class: " + factory.getClass());
+      }
+    } catch (Exception ignore) {
+    }
+  }
+
+  private static void setFactoryProperties(Object factory) {
+    setFeatureQuietly(factory, XMLConstants.FEATURE_SECURE_PROCESSING, true);
+    setFeatureQuietly(factory, "http://apache.org/xml/features/disallow-doctype-decl", true);
+    setFeatureQuietly(factory, "http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
+    setFeatureQuietly(factory, "http://xml.org/sax/features/external-general-entities", false);
+    setFeatureQuietly(factory, "http://xml.org/sax/features/external-parameter-entities", false);
+    // Values from XMLConstants inlined for JDK 1.6 compatibility
+    setAttributeQuietly(factory, "http://javax.xml.XMLConstants/property/accessExternalDTD", "");
+    setAttributeQuietly(factory, "http://javax.xml.XMLConstants/property/accessExternalSchema", "");
+    setAttributeQuietly(factory, "http://javax.xml.XMLConstants/property/accessExternalStylesheet", "");
+  }
+
+  private static void setPropertyQuietly(Object factory, String name, Object value) {
+    try {
+      if (factory instanceof XMLReader) {
+        ((XMLReader) factory).setProperty(name, value);
+      } else if (factory instanceof XMLInputFactory) {
+        ((XMLInputFactory) factory).setProperty(name, value);
+      } else {
+        throw new Error("Invalid factory class: " + factory.getClass());
+      }
+    } catch (Exception ignore) {
+    }
+  }
+}

pgjdbc/src/main/java/org/postgresql/xml/EmptyStringEntityResolver.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ * See the LICENSE file in the project root for more information.
+ */
+
+package org.postgresql.xml;
+
+import org.xml.sax.EntityResolver;
+import org.xml.sax.InputSource;
+import org.xml.sax.SAXException;
+
+import java.io.IOException;
+import java.io.StringReader;
+
+public class EmptyStringEntityResolver implements EntityResolver {
+  public static final EmptyStringEntityResolver INSTANCE = new EmptyStringEntityResolver();
+
+  @Override
+  public InputSource resolveEntity(String publicId, String systemId)
+      throws SAXException, IOException {
+    return new InputSource(new StringReader(""));
+  }
+}