Validate Host header of incoming HTTP requests (#3212)

* Validate Host header of incoming HTTP requests

* Always allow requests with loopback IP addresses and localhost

* Split off ValidateHostHandler to a separate file

* Allow IPv4-mapped loopback addresses in ValidateHostHandler

* Add error description to 404 error returned by ValidateHostHandler

* Add refine.interface parameter to override interface and host separately

* Fix some whitespace inconsistencies

* Update refine and refine.bat with separate host and interface arguments

* Add -h switch to usage message

* Use -H instead of -h for the host argument

* Bring changes in line with new Jetty version

Co-authored-by: Antonin Delpeuch <antonin@delpeuch.eu>

refine

@@ -34,9 +34,12 @@ where [options] include:
   -p <port> the port that OpenRefine will listen to
      default: 3333
 
-  -i <interface> the host interface OpenRefine should bind to
+  -i <interface> the network interface OpenRefine should bind to
      default: 127.0.0.1
 	 
+  -H <host> the expected value for the Host header (set to * to disable checks)
+     default: <interface>
+
   -w <path> path to the webapp
      default: main/webapp
 
@@ -151,7 +154,7 @@ check_pywin32() {
 
 check_running() {
     check_downloaders
-    URL="http://${REFINE_HOST}:${REFINE_PORT}/"
+    URL="http://${REFINE_HOST_INTERNAL}:${REFINE_PORT}/"
     CHECK_STR="<title>OpenRefine</title>"
 
     if [ "$CURL" ] ; then
@@ -258,7 +261,7 @@ tool_download() {
 load_data() {
     FILE=$1
     NAME=$2
-    URL="http://${REFINE_HOST}:${REFINE_PORT}/command/core/create-project-from-upload"
+    URL="http://${REFINE_HOST_INTERNAL}:${REFINE_PORT}/command/core/create-project-from-upload"
     CURL="`which curl 2> /dev/null`"
     
     if [ -z "$CURL" ] ; then
@@ -516,7 +519,7 @@ ui_test() {
     echo ""
 
     echo "Starting Cypress..."
-    CYPRESS_RUN_CMD="yarn --cwd ./main/tests/cypress run cypress run --browser $BROWSER --headless --quiet --reporter list --env OPENREFINE_URL=http://$REFINE_HOST:$REFINE_PORT"
+    CYPRESS_RUN_CMD="yarn --cwd ./main/tests/cypress run cypress run --browser $BROWSER --headless --quiet --reporter list --env OPENREFINE_URL=http://$REFINE_HOST_INTERNAL:$REFINE_PORT"
     if [ "$CYPRESS_RECORD" = "1" ] ; then
         # if tests are recorded, project id is added to env vars, and --record flag is added to the cmd-line
         export CYPRESS_PROJECT_ID=$CYPRESS_PROJECT_ID
@@ -596,6 +599,10 @@ run() {
         add_option "-Drefine.port=$REFINE_PORT"
     fi
     
+    if [ "$REFINE_INTERFACE" ] ; then
+        add_option "-Drefine.interface=$REFINE_INTERFACE"
+    fi
+    
     if [ "$REFINE_HOST" ] ; then
         add_option "-Drefine.host=$REFINE_HOST"
     fi
@@ -609,7 +616,7 @@ run() {
     RUN_CMD=("$JAVA" -cp "$CLASSPATH" "${OPTS[@]}" "com.google.refine.Refine")
     echo "${RUN_CMD[@]}"
 
-    echo "Starting OpenRefine at 'http://${REFINE_HOST}:${REFINE_PORT}/'"
+    echo "Starting OpenRefine at 'http://${REFINE_HOST_INTERNAL}:${REFINE_PORT}/'"
     echo ""
 
     if [ -z "$FORK" ] ; then
@@ -654,7 +661,7 @@ broker_run() {
     #echo "$RUN_CMD"
     #echo ""
   
-    echo "Starting OpenRefine Broker at 'http://${REFINE_HOST}:${REFINE_PORT}/'"
+    echo "Starting OpenRefine Broker at 'http://0.0.0.0:${REFINE_PORT}/'"
     echo ""
 
     if [ -z "$FORK" ] ; then
@@ -826,7 +833,8 @@ while [ $# -ne 0 ] ; do
   case "$1" in
 	-h) usage;;
     -p) shift; REFINE_PORT="$1"; shift; continue;;
-    -i) shift; REFINE_HOST="$1"; shift; continue;;
+    -H) shift; REFINE_HOST="$1"; shift; continue;;
+    -i) shift; REFINE_INTERFACE="$1"; shift; continue;;
     -w) shift; REFINE_WEBAPP="$1"; shift; continue;;
     -d) shift; REFINE_DATA_DIR="$1"; shift; continue;;
     -m) 
@@ -892,8 +900,23 @@ if [ -z "$REFINE_PORT" ] ; then
     REFINE_PORT="3333"
 fi
 
+if [ -z "$REFINE_INTERFACE" ] ; then
+    REFINE_INTERFACE="127.0.0.1"
+fi
+
 if [ -z "$REFINE_HOST" ] ; then
-    REFINE_HOST="127.0.0.1"
+    if [ "$REFINE_INTERFACE" = "0.0.0.0" ] ; then
+        REFINE_HOST='*'
+    else
+        REFINE_HOST="$REFINE_INTERFACE"
+    fi
+fi
+
+if [ "$REFINE_HOST" = '*' ] ; then
+    echo No host specified while binding to interface 0.0.0.0, guessing localhost.
+    REFINE_HOST_INTERNAL="localhost"
+else
+    REFINE_HOST_INTERNAL="$REFINE_HOST"
 fi
 
 if [ -z "$REFINE_WEBAPP" ] ; then

refine.bat

@@ -1,5 +1,4 @@
-rem Changing this for debugging on Appveyor
+@echo off
-rem @echo off
 rem
 rem Configuration variables
 rem
@@ -29,9 +28,12 @@ echo.
 echo  "/p <port>" the port that OpenRefine will listen to
 echo     default: 3333
 echo.
-echo  "/i <interface>" the host interface OpenRefine should bind to
+echo  "/i <interface>" the network interface OpenRefine should bind to
 echo     default: 127.0.0.1
 echo.
+echo  "/H <host>" the expected value for the Host header (set to * to disable checks)
+echo     default: ^<interface^>
+echo.
 echo  "/w <path>" path to the webapp
 echo     default src\main\webapp
 echo.
@@ -99,10 +101,11 @@ rem --- Argument parsing --------------------------------------------
 
 :loop
 if ""%1"" == """" goto endArgumentParsing
-if ""%1"" == ""/h"" goto usage
 if ""%1"" == ""/?"" goto usage
+if ""%1"" == ""/h"" goto usage
 if ""%1"" == ""/p"" goto arg-p
 if ""%1"" == ""/i"" goto arg-i
+if ""%1"" == ""/H"" goto arg-H
 if ""%1"" == ""/w"" goto arg-w
 if ""%1"" == ""/d"" goto arg-d
 if ""%1"" == ""/m"" goto arg-m
@@ -114,6 +117,10 @@ set REFINE_PORT=%2
 goto shift2loop
 
 :arg-i
+set REFINE_INTERFACE=%2
+goto shift2loop
+
+:arg-H
 set REFINE_HOST=%2
 goto shift2loop
 
@@ -165,10 +172,17 @@ set REFINE_PORT=3333
 :gotPort
 set OPTS=%OPTS% -Drefine.port=%REFINE_PORT%
 
+if not "%REFINE_INTERFACE%" == "" goto gotInterface
+set REFINE_INTERFACE=127.0.0.1
+:gotInterface
+set OPTS=%OPTS% -Drefine.interface=%REFINE_INTERFACE%
+
 if not "%REFINE_HOST%" == "" goto gotHost
-set REFINE_HOST=127.0.0.1
+if "%REFINE_INTERFACE%" == "" goto skipHost
+set REFINE_HOST=%REFINE_INTERFACE%
 :gotHost
 set OPTS=%OPTS% -Drefine.host=%REFINE_HOST%
+:skipHost
 
 if not "%REFINE_WEBAPP%" == "" goto gotWebApp
 set REFINE_WEBAPP=main\webapp

server/src/com/google/refine/Refine.java

@@ -75,11 +75,12 @@ import com.google.refine.Configurations;
  */
 public class Refine {
     
-    static private final String DEFAULT_HOST = "127.0.0.1";
+    static private final String DEFAULT_IFACE = "127.0.0.1";
     static private final int DEFAULT_PORT = 3333;
         
     static private int port;
     static private String host;
+    static private String iface;
 
     final static Logger logger = LoggerFactory.getLogger("refine");
         
@@ -100,8 +101,12 @@ public class Refine {
         // set the log verbosity level
         org.apache.log4j.Logger.getRootLogger().setLevel(Level.toLevel(Configurations.get("refine.verbosity","info")));
 
-        port = Configurations.getInteger("refine.port",DEFAULT_PORT);
+        port = Configurations.getInteger("refine.port", DEFAULT_PORT);
-        host = Configurations.get("refine.host",DEFAULT_HOST);
+        iface = Configurations.get("refine.interface", DEFAULT_IFACE);
+        host = Configurations.get("refine.host", iface);
+        if ("0.0.0.0".equals(host)) {
+            host = "*";
+        }
 
         Refine refine = new Refine();
         
@@ -111,7 +116,7 @@ public class Refine {
     public void init(String[] args) throws Exception {
 
         RefineServer server = new RefineServer();
-        server.init(host,port);
+        server.init(iface, port, host);
 
         boolean headless = Configurations.getBoolean("refine.headless",false);
         if (headless) {
@@ -120,7 +125,16 @@ public class Refine {
         } else {
             try {
                 RefineClient client = new RefineClient();
+                if ("*".equals(host)) {
+                    if ("0.0.0.0".equals(iface)) {
+                        logger.warn("No refine.host specified while binding to interface 0.0.0.0, guessing localhost.");
+                        client.init("localhost",port);
+                    } else { 
+                        client.init(iface,port);
+                    }
+                } else {
                     client.init(host,port);
+                }
             } catch (Exception e) {
                 logger.warn("Sorry, some error prevented us from launching the browser for you.\n\n Point your browser to http://" + host + ":" + port + "/ to start using Refine.");
             }
@@ -155,8 +169,8 @@ class RefineServer extends Server {
         
     private ThreadPoolExecutor threadPool;
     
-    public void init(String host, int port) throws Exception {
+    public void init(String iface, int port, String host) throws Exception {
-        logger.info("Starting Server bound to '" + host + ":" + port + "'");
+        logger.info("Starting Server bound to '" + iface + ":" + port + "'");
 
         String memory = Configurations.get("refine.memory");
         if (memory != null) {
@@ -168,7 +182,7 @@ class RefineServer extends Server {
         HttpConnectionFactory httpFactory = new HttpConnectionFactory(httpConfig);
         ServerConnector connector = new ServerConnector(this, httpFactory);
         connector.setPort(port);
-        connector.setHost(host);
+        connector.setHost(iface);
         connector.setIdleTimeout(Configurations.getInteger("server.connection.max_idle_time",60000));
         this.addConnector(connector);
 
@@ -192,7 +206,14 @@ class RefineServer extends Server {
         WebAppContext context = new WebAppContext(webapp.getAbsolutePath(), contextPath);
         context.setMaxFormContentSize(maxFormContentSize);
 
+        if ("*".equals(host)) {
             this.setHandler(context);
+        } else {
+            ValidateHostHandler wrapper = new ValidateHostHandler(host);
+            wrapper.setHandler(context);
+            this.setHandler(wrapper);
+        }
+        
         this.setStopAtShutdown(true);
         StatisticsHandler handler = new StatisticsHandler();
         handler.setServer(this);
@@ -485,12 +506,7 @@ class RefineClient extends JFrame implements ActionListener {
     private URI uri;
     
     public void init(String host, int port) throws Exception {
-
+        uri = new URI("http://" + host + ":" + port + "/");
-    	String cleanedHost = host;
-    	if("0.0.0.0".equals(host)) {
-            cleanedHost = "localhost";
-        }
-        uri = new URI("http://" + cleanedHost + ":" + port + "/");
         openBrowser();
     }
     

server/src/com/google/refine/ValidateHostHandler.java

@@ -0,0 +1,104 @@
+/*******************************************************************************
+ * Copyright (C) 2020, OpenRefine contributors
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ ******************************************************************************/
+
+package com.google.refine;
+
+import java.io.IOException;
+import java.util.regex.Pattern;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import org.eclipse.jetty.server.handler.HandlerWrapper;
+import org.eclipse.jetty.server.Request;
+
+/**
+ * Validate the Host header of the HTTP request to see if it matches either a loopback IP
+ * address, localhost or an explicitly specified hostname. This is required to avoid DNS
+ * rebinding attacks against users running OpenRefine on their desktop computers.
+ */
+class ValidateHostHandler extends HandlerWrapper {
+
+    /**
+     * Matches:
+     *  - addresses in the 127.0.0.0/8 subnet
+     *  - IPv4-mapped addresses in the ::ffff:7f00:00/104 subnet
+     *  - different representations of ::1
+     *  - localhost
+     * Matching is a little fuzzy to simplify the regular expression - it expects the Host
+     * header to be well-formed. Some invalid addresses would be accepted, for example:
+     *  - 127.6..64.245
+     *  - 0::0:::0:00:1
+     * This is not a problem however, as these are not valid DNS names either, and should
+     * never be sent by a well-behaved browser - and validating the host header only ever
+     * helps if the browser works as expected and cannot be used to fake the Host header.
+     */
+    static private final Pattern LOOPBACK_PATTERN = Pattern
+            .compile("^(?:127\\.[0-9\\.]*|\\[[0\\:]*\\:(?:ffff\\:7f[0-9a-f]{2}:[0-9a-f]{1,4}|0{0,3}1)\\]|localhost)(?:\\:[0-9]+)?$", Pattern.CASE_INSENSITIVE);
+
+    private String expectedHost;
+
+    public ValidateHostHandler(String expectedHost) {
+        this.expectedHost = expectedHost;
+    }
+
+    public boolean isValidHost(String host) {
+
+        // Allow loopback IPv4 and IPv6 addresses, as well as localhost
+        if (LOOPBACK_PATTERN.matcher(host).find()) {
+            return true;
+        }
+
+        // Strip port from hostname - for IPv6 addresses, if
+        // they end with a bracket, then there is no port
+        int index = host.lastIndexOf(':');
+        if (index > 0 && !host.endsWith("]")) {
+            host = host.substring(0, index);
+        }
+
+        // Strip brackets from IPv6 addresses
+        if (host.startsWith("[") && host.endsWith("]")) {
+            host = host.substring(1, host.length() - 2);
+        }
+
+        // Allow only if stripped hostname matches expected hostname
+        return expectedHost.equalsIgnoreCase(host);
+    }
+
+    @Override
+    public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response)
+            throws IOException, ServletException {
+        String host = request.getHeader("Host");
+        if (isValidHost(host)) {
+            super.handle(target, baseRequest, request, response);
+        } else {
+            // Return HTTP 404 Not Found, since we are
+            // not serving content for the requested URL
+            response.sendError(HttpServletResponse.SC_NOT_FOUND, "Invalid hostname");
+        }
+    }
+
+}