org.apache.hadoop.fs.DefaultFileAccess.java Source code

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Here is the source code for org.apache.hadoop.fs.DefaultFileAccess.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
 *
 *     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.fs;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.security.AccessControlException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.EnumSet;
import java.util.List;

import javax.security.auth.login.LoginException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.permission.FsAction;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hive.shims.ShimLoader;
import org.apache.hadoop.hive.shims.Utils;
import org.apache.hadoop.security.UserGroupInformation;

/**
 * Implements the default file access logic for HadoopShims.checkFileAccess(), for Hadoop
 * versions which do not implement FileSystem.access().
 *
 */
public class DefaultFileAccess {

    private static Log LOG = LogFactory.getLog(DefaultFileAccess.class);

    private static List<String> emptyGroups = new ArrayList<String>(0);

    public static void checkFileAccess(FileSystem fs, FileStatus stat, FsAction action)
            throws IOException, AccessControlException, LoginException {
        // Get the user/groups for checking permissions based on the current UGI.
        UserGroupInformation currentUgi = Utils.getUGI();
        DefaultFileAccess.checkFileAccess(fs, stat, action, currentUgi.getShortUserName(),
                Arrays.asList(currentUgi.getGroupNames()));
    }

    public static void checkFileAccess(FileSystem fs, FileStatus stat, FsAction action, String user,
            List<String> groups) throws IOException, AccessControlException {

        if (groups == null) {
            groups = emptyGroups;
        }

        String superGroupName = getSuperGroupName(fs.getConf());
        if (userBelongsToSuperGroup(superGroupName, groups)) {
            LOG.info("User \"" + user + "\" belongs to super-group \"" + superGroupName + "\". "
                    + "Permission granted for action: " + action + ".");
            return;
        }

        final FsPermission dirPerms = stat.getPermission();
        final String grp = stat.getGroup();

        if (user.equals(stat.getOwner())) {
            if (dirPerms.getUserAction().implies(action)) {
                return;
            }
        } else if (groups.contains(grp)) {
            if (dirPerms.getGroupAction().implies(action)) {
                return;
            }
        } else if (dirPerms.getOtherAction().implies(action)) {
            return;
        }
        throw new AccessControlException(
                "action " + action + " not permitted on path " + stat.getPath() + " for user " + user);
    }

    private static String getSuperGroupName(Configuration configuration) {
        return configuration.get("dfs.permissions.supergroup", "");
    }

    private static boolean userBelongsToSuperGroup(String superGroupName, List<String> groups) {
        return groups.contains(superGroupName);
    }
}