1 files changed, 166 insertions, 0 deletions
diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/util/introspection/SecureIntrospectorImpl.java b/velocity-engine-core/src/main/java/org/apache/velocity/util/introspection/SecureIntrospectorImpl.java
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--- /dev/null
+++ b/velocity-engine-core/src/main/java/org/apache/velocity/util/introspection/SecureIntrospectorImpl.java
@@ -0,0 +1,166 @@
+package org.apache.velocity.util.introspection;
+
+/*
+ * 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.
+ */
+
+import org.slf4j.Logger;
+
+import java.lang.reflect.Method;
+
+/**
+ * <p>Prevent "dangerous" classloader/reflection related calls.  Use this
+ * introspector for situations in which template writers are numerous
+ * or untrusted.  Specifically, this introspector prevents creation of
+ * arbitrary objects and prevents reflection on objects.
+ *
+ * <p>See documentation of checkObjectExecutePermission() for
+ * more information on specific classes and methods blocked.
+ *
+ * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
+ * @version $Id$
+ * @since 1.5
+ */
+public class SecureIntrospectorImpl extends Introspector implements SecureIntrospectorControl
+{
+    private String[] badClasses;
+    private String[] badPackages;
+
+    public SecureIntrospectorImpl(String[] badClasses, String[] badPackages, Logger log)
+    {
+        super(log);
+        this.badClasses = badClasses;
+        this.badPackages = badPackages;
+    }
+
+    /**
+     * Get the Method object corresponding to the given class, name and parameters.
+     * Will check for appropriate execute permissions and return null if the method
+     * is not allowed to be executed.
+     *
+     * @param clazz Class on which method will be called
+     * @param methodName Name of method to be called
+     * @param params array of parameters to method
+     * @return Method object retrieved by Introspector
+     * @throws IllegalArgumentException The parameter passed in were incorrect.
+     */
+    @Override
+    public Method getMethod(Class<?> clazz, String methodName, Object[] params)
+        throws IllegalArgumentException
+    {
+        if (!checkObjectExecutePermission(clazz, methodName))
+        {
+            log.warn("Cannot retrieve method {} from object of class {} due to security restrictions."
+                     , methodName, clazz.getName());
+            return null;
+        }
+        else
+        {
+            return super.getMethod(clazz, methodName, params);
+        }
+    }
+
+    /**
+     * Determine which methods and classes to prevent from executing.  Always blocks
+     * methods wait() and notify().  Always allows methods on Number, Boolean, and String.
+     * Prohibits method calls on classes related to reflection and system operations.
+     * For the complete list, see the properties <code>introspector.restrict.classes</code>
+     * and <code>introspector.restrict.packages</code>.
+     *
+     * @param clazz Class on which method will be called
+     * @param methodName Name of method to be called
+     * @see org.apache.velocity.util.introspection.SecureIntrospectorControl#checkObjectExecutePermission(java.lang.Class, java.lang.String)
+     */
+    @Override
+    public boolean checkObjectExecutePermission(Class<?> clazz, String methodName)
+    {
+        /*
+         * check for wait and notify
+         */
+        if (methodName != null &&
+            (methodName.equals("wait") || methodName.equals("notify")) )
+        {
+            return false;
+        }
+
+        /*
+         * Always allow the most common classes - Number, Boolean and String
+         */
+        else if (Number.class.isAssignableFrom(clazz))
+        {
+            return true;
+        }
+        else if (Boolean.class.isAssignableFrom(clazz))
+        {
+            return true;
+        }
+        else if (String.class.isAssignableFrom(clazz))
+        {
+            return true;
+        }
+
+        /*
+         * Always allow Class.getName()
+         */
+        else if (Class.class.isAssignableFrom(clazz) &&
+                 (methodName != null) && methodName.equals("getName"))
+        {
+            return true;
+        }
+
+       /*
+       * Always disallow ClassLoader, Thread and subclasses
+       */
+        if (ClassLoader.class.isAssignableFrom(clazz) ||
+                Thread.class.isAssignableFrom(clazz))
+        {
+            return false;
+        }
+
+        /*
+         * check the classname (minus any array info)
+         * whether it matches disallowed classes or packages
+         */
+        String className = clazz.getName();
+        if (className.startsWith("[L") && className.endsWith(";"))
+        {
+            className = className.substring(2, className.length() - 1);
+        }
+
+        int dotPos = className.lastIndexOf('.');
+        String packageName = (dotPos == -1) ? "" : className.substring(0, dotPos);
+
+        for (String badPackage : badPackages)
+        {
+            if (packageName.equals(badPackage))
+            {
+                return false;
+            }
+        }
+
+        for (String badClass : badClasses)
+        {
+            if (className.equals(badClass))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}