org.apache.hadoop.security.AuthenticationWithProxyUserFilter.java Source code

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Here is the source code for org.apache.hadoop.security.AuthenticationWithProxyUserFilter.java

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/**
 * 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.security;

import org.apache.hadoop.security.authentication.server.AuthenticationFilter;
import org.apache.hadoop.security.authorize.AuthorizationException;
import org.apache.hadoop.security.authorize.ProxyUsers;
import org.apache.hadoop.util.HttpExceptionUtils;
import org.apache.http.NameValuePair;
import org.apache.http.client.utils.URLEncodedUtils;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.List;

/**
 * Extend the function of {@link AuthenticationFilter} to
 * support authorizing proxy user. If the query string
 * contains doAs parameter, then check the proxy user,
 * otherwise do the next filter.
 */
public class AuthenticationWithProxyUserFilter extends AuthenticationFilter {

    /**
     * Constant used in URL's query string to perform a proxy user request, the
     * value of the <code>DO_AS</code> parameter is the user the request will be
     * done on behalf of.
     */
    private static final String DO_AS = "doAs";

    private static final Charset UTF8_CHARSET = Charset.forName("UTF-8");

    /**
     * This method provide the ability to do pre/post tasks
     * in filter chain. Override this method to authorize
     * proxy user between AuthenticationFilter and next filter.
     * @param filterChain the filter chain object.
     * @param request the request object.
     * @param response the response object.
     *
     * @throws IOException
     * @throws ServletException
     */
    @Override
    protected void doFilter(FilterChain filterChain, HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {

        // authorize proxy user before calling next filter.
        String proxyUser = getDoAs(request);
        if (proxyUser != null) {
            UserGroupInformation realUser = UserGroupInformation.createRemoteUser(request.getRemoteUser());
            UserGroupInformation proxyUserInfo = UserGroupInformation.createProxyUser(proxyUser, realUser);

            try {
                ProxyUsers.authorize(proxyUserInfo, request.getRemoteAddr());
            } catch (AuthorizationException ex) {
                HttpExceptionUtils.createServletExceptionResponse(response, HttpServletResponse.SC_FORBIDDEN, ex);
                // stop filter chain if there is an Authorization Exception.
                return;
            }

            final UserGroupInformation finalProxyUser = proxyUserInfo;
            // Change the remote user after proxy user is authorized.
            request = new HttpServletRequestWrapper(request) {
                @Override
                public String getRemoteUser() {
                    return finalProxyUser.getUserName();
                }
            };

        }
        filterChain.doFilter(request, response);
    }

    /**
     * Get proxy user from query string.
     * @param request the request object
     * @return proxy user
     */
    public static String getDoAs(HttpServletRequest request) {
        String queryString = request.getQueryString();
        if (queryString == null) {
            return null;
        }
        List<NameValuePair> list = URLEncodedUtils.parse(queryString, UTF8_CHARSET);
        if (list != null) {
            for (NameValuePair nv : list) {
                if (DO_AS.equalsIgnoreCase(nv.getName())) {
                    return nv.getValue();
                }
            }
        }
        return null;
    }
}