HADOOP-6151. Added a input filter to all of the http servlets that quotes

html characters in the parameters, to prevent cross site scripting 
attacks. (omalley)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@816703 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -1035,6 +1035,10 @@ Trunk (unreleased changes)
     HADOOP-6257. Two TestFileSystem classes are confusing
     hadoop-hdfs-hdfwithmr. (Philip Zeyliger via tomwhite)
 
+    HADOOP-6151. Added a input filter to all of the http servlets that quotes
+    html characters in the parameters, to prevent cross site scripting 
+    attacks. (omalley)
+
 Release 0.20.1 - Unreleased
 
   INCOMPATIBLE CHANGES

src/java/org/apache/hadoop/http/HtmlQuoting.java

@@ -0,0 +1,198 @@
+/**
+ * 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.hadoop.http;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * This class is responsible for quoting HTML characters.
+ */
+public class HtmlQuoting {
+  private static final byte[] ampBytes = "&".getBytes();
+  private static final byte[] aposBytes = "'".getBytes();
+  private static final byte[] gtBytes = ">".getBytes();
+  private static final byte[] ltBytes = "<".getBytes();
+  private static final byte[] quotBytes = """.getBytes();
+
+  /**
+   * Does the given string need to be quoted?
+   * @param data the string to check
+   * @param off the starting position
+   * @param len the number of bytes to check
+   * @return does the string contain any of the active html characters?
+   */
+  public static boolean needsQuoting(byte[] data, int off, int len) {
+    for(int i=off; i< off+len; ++i) {
+      switch(data[i]) {
+      case '&':
+      case '<':
+      case '>':
+      case '\'':
+      case '"':
+        return true;
+      default:
+        break;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Does the given string need to be quoted?
+   * @param str the string to check
+   * @return does the string contain any of the active html characters?
+   */
+  public static boolean needsQuoting(String str) {
+    byte[] bytes = str.getBytes();
+    return needsQuoting(bytes, 0 , bytes.length);
+  }
+
+  /**
+   * Quote all of the active HTML characters in the given string as they
+   * are added to the buffer.
+   * @param output the stream to write the output to
+   * @param buffer the byte array to take the characters from
+   * @param off the index of the first byte to quote
+   * @param len the number of bytes to quote
+   */
+  public static void quoteHtmlChars(OutputStream output, byte[] buffer,
+                                    int off, int len) throws IOException {
+    for(int i=off; i < off+len; i++) {
+      switch (buffer[i]) {
+      case '&': output.write(ampBytes); break;
+      case '<': output.write(ltBytes); break;
+      case '>': output.write(gtBytes); break;
+      case '\'': output.write(aposBytes); break;
+      case '"': output.write(quotBytes); break;
+      default: output.write(buffer, i, 1);
+      }
+    }
+  }
+  
+  /**
+   * Quote the given item to make it html-safe.
+   * @param item the string to quote
+   * @return the quoted string
+   */
+  public static String quoteHtmlChars(String item) {
+    byte[] bytes = item.getBytes();
+    if (needsQuoting(bytes, 0, bytes.length)) {
+      ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+      try {
+        quoteHtmlChars(buffer, bytes, 0, bytes.length);
+      } catch (IOException ioe) {
+        // Won't happen, since it is a bytearrayoutputstream
+      }
+      return buffer.toString();
+    } else {
+      return item;
+    }
+  }
+
+  /**
+   * Return an output stream that quotes all of the output.
+   * @param out the stream to write the quoted output to
+   * @return a new stream that the application show write to
+   * @throws IOException if the underlying output fails
+   */
+  public static OutputStream quoteOutputStream(final OutputStream out
+                                               ) throws IOException {
+    return new OutputStream() {
+      private byte[] data = new byte[1];
+      @Override
+      public void write(byte[] data, int off, int len) throws IOException {
+        quoteHtmlChars(out, data, off, len);
+      }
+      
+      @Override
+      public void write(int b) throws IOException {
+        data[0] = (byte) b;
+        quoteHtmlChars(out, data, 0, 1);
+      }
+      
+      @Override
+      public void flush() throws IOException {
+        out.flush();
+      }
+      
+      @Override
+      public void close() throws IOException {
+        out.close();
+      }
+    };
+  }
+
+  /**
+   * Remove HTML quoting from a string.
+   * @param item the string to unquote
+   * @return the unquoted string
+   */
+  public static String unquoteHtmlChars(String item) {
+    int next = item.indexOf('&');
+    // nothing was quoted
+    if (next == -1) {
+      return item;
+    }
+    int len = item.length();
+    int posn = 0;
+    StringBuilder buffer = new StringBuilder();
+    while (next != -1) {
+      buffer.append(item.substring(posn, next));
+      if (item.startsWith("&amp;", next)) {
+        buffer.append('&');
+        next += 5;
+      } else if (item.startsWith("&apos;", next)) {
+        buffer.append('\'');
+        next += 6;        
+      } else if (item.startsWith("&gt;", next)) {
+        buffer.append('>');
+        next += 4;
+      } else if (item.startsWith("&lt;", next)) {
+        buffer.append('<');
+        next += 4;
+      } else if (item.startsWith("&quot;", next)) {
+        buffer.append('"');
+        next += 6;
+      } else {
+        int end = item.indexOf(';', next)+1;
+        if (end == 0) {
+          end = len;
+        }
+        throw new IllegalArgumentException("Bad HTML quoting for " + 
+                                           item.substring(next,end));
+      }
+      posn = next;
+      next = item.indexOf('&', posn);
+    }
+    buffer.append(item.substring(posn, len));
+    return buffer.toString();
+  }
+  
+  public static void main(String[] args) throws Exception {
+    for(String arg:args) {
+      System.out.println("Original: " + arg);
+      String quoted = quoteHtmlChars(arg);
+      System.out.println("Quoted: "+ quoted);
+      String unquoted = unquoteHtmlChars(quoted);
+      System.out.println("Unquoted: " + unquoted);
+      System.out.println();
+    }
+  }
+}

src/java/org/apache/hadoop/http/HttpServer.java

@@ -23,14 +23,20 @@
 import java.net.InetSocketAddress;
 import java.net.URL;
 import java.util.ArrayList;
+import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.nio.channels.ServerSocketChannel;
 
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
 import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletRequestWrapper;
 import javax.servlet.http.HttpServletResponse;
 
 import org.apache.commons.logging.Log;
@@ -117,6 +123,7 @@ public HttpServer(String name, String bindAddress, int port,
 
     addDefaultApps(contexts, appDir);
 
+    addGlobalFilter("safety", QuotingInputFilter.class.getName(), null);
     final FilterInitializer[] initializers = getFilterInitializers(conf); 
     if (initializers != null) {
       for(FilterInitializer c : initializers) {
@@ -512,10 +519,99 @@ public static class StackServlet extends HttpServlet {
     public void doGet(HttpServletRequest request, HttpServletResponse response)
       throws ServletException, IOException {
       
-      PrintWriter out = new PrintWriter(response.getOutputStream());
+      PrintWriter out = new PrintWriter
+                    (HtmlQuoting.quoteOutputStream(response.getOutputStream()));
       ReflectionUtils.printThreadInfo(out, "");
       out.close();
       ReflectionUtils.logThreadInfo(LOG, "jsp requested", 1);      
     }
   }
+  
+  /**
+   * A Servlet input filter that quotes all HTML active characters in the
+   * parameter names and values. The goal is to quote the characters to make
+   * all of the servlets resistant to cross-site scripting attacks.
+   */
+  public static class QuotingInputFilter implements Filter {
+
+    public static class RequestQuoter extends HttpServletRequestWrapper {
+      private final HttpServletRequest rawRequest;
+      public RequestQuoter(HttpServletRequest rawRequest) {
+        super(rawRequest);
+        this.rawRequest = rawRequest;
+      }
+      
+      /**
+       * Return the set of parameter names, quoting each name.
+       */
+      @SuppressWarnings("unchecked")
+      @Override
+      public Enumeration<String> getParameterNames() {
+        return new Enumeration<String>() {
+          private Enumeration<String> rawIterator = 
+            rawRequest.getParameterNames();
+          @Override
+          public boolean hasMoreElements() {
+            return rawIterator.hasMoreElements();
+          }
+
+          @Override
+          public String nextElement() {
+            return HtmlQuoting.quoteHtmlChars(rawIterator.nextElement());
+          }
+        };
+      }
+      
+      /**
+       * Unquote the name and quote the value.
+       */
+      @Override
+      public String getParameter(String name) {
+        return HtmlQuoting.quoteHtmlChars(rawRequest.getParameter
+                                     (HtmlQuoting.unquoteHtmlChars(name)));
+      }
+      
+      @Override
+      public String[] getParameterValues(String name) {
+        String unquoteName = HtmlQuoting.unquoteHtmlChars(name);
+        String[] unquoteValue = rawRequest.getParameterValues(unquoteName);
+        String[] result = new String[unquoteValue.length];
+        for(int i=0; i < result.length; ++i) {
+          result[i] = HtmlQuoting.quoteHtmlChars(unquoteValue[i]);
+        }
+        return result;
+      }
+
+      @SuppressWarnings("unchecked")
+      @Override
+      public Map<String, String> getParameterMap() {
+        Map<String, String> result = new HashMap<String,String>();
+        Map<String, String> raw = rawRequest.getParameterMap();
+        for (Map.Entry<String,String> item: raw.entrySet()) {
+          result.put(HtmlQuoting.quoteHtmlChars(item.getKey()), 
+                     HtmlQuoting.quoteHtmlChars(item.getValue()));
+        }
+        return result;
+      }
+    }
+
+    @Override
+    public void init(FilterConfig config) throws ServletException {
+    }
+
+    @Override
+    public void destroy() {
+    }
+
+    @Override
+    public void doFilter(ServletRequest request, 
+                         ServletResponse response,
+                         FilterChain chain
+                         ) throws IOException, ServletException {
+      HttpServletRequestWrapper quoted = 
+        new RequestQuoter((HttpServletRequest) request);
+      chain.doFilter(quoted, response);
+    }
+
+  }
 }

src/test/core/org/apache/hadoop/http/TestHtmlQuoting.java

@@ -0,0 +1,62 @@
+/**
+ * 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.hadoop.http;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+public class TestHtmlQuoting {
+
+  @Test public void testNeedsQuoting() throws Exception {
+    assertTrue(HtmlQuoting.needsQuoting("abcde>"));
+    assertTrue(HtmlQuoting.needsQuoting("<abcde"));
+    assertTrue(HtmlQuoting.needsQuoting("abc'de"));
+    assertTrue(HtmlQuoting.needsQuoting("abcde\""));
+    assertTrue(HtmlQuoting.needsQuoting("&"));
+    assertFalse(HtmlQuoting.needsQuoting(""));
+    assertFalse(HtmlQuoting.needsQuoting("ab\ncdef"));
+  }
+
+  @Test public void testQuoting() throws Exception {
+    assertEquals("ab&lt;cd", HtmlQuoting.quoteHtmlChars("ab<cd"));
+    assertEquals("ab&gt;", HtmlQuoting.quoteHtmlChars("ab>"));
+    assertEquals("&amp;&amp;&amp;", HtmlQuoting.quoteHtmlChars("&&&"));
+    assertEquals(" &apos;\n", HtmlQuoting.quoteHtmlChars(" '\n"));
+    assertEquals("&quot;", HtmlQuoting.quoteHtmlChars("\""));
+  }
+
+  private void runRoundTrip(String str) throws Exception {
+    assertEquals(str, 
+                 HtmlQuoting.unquoteHtmlChars(HtmlQuoting.quoteHtmlChars(str)));
+  }
+  
+  @Test public void testRoundtrip() throws Exception {
+    runRoundTrip("");
+    runRoundTrip("<>&'\"");
+    runRoundTrip("ab>cd<ef&ghi'\"");
+    runRoundTrip("A string\n with no quotable chars in it!");
+    StringBuilder buffer = new StringBuilder();
+    for(char ch=0; ch < 127; ++ch) {
+      buffer.append(ch);
+    }
+    runRoundTrip(buffer.toString());
+  }
+}