org.apache.sqoop.util.SubprocessSecurityManager.java Source code

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Here is the source code for org.apache.sqoop.util.SubprocessSecurityManager.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.sqoop.util;

import java.security.Permission;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * A SecurityManager used to run subprocesses and disallow certain actions.
 *
 * This specifically disallows System.exit().
 *
 * This SecurityManager will also check with any existing SecurityManager as
 * to the validity of any permissions. The SubprocessSecurityManager should be
 * installed with the install() method, which will retain a handle to any
 * previously-installed SecurityManager instance.
 *
 * When this SecurityManager is no longer necessary, the uninstall() method
 * should be used which reinstates the previous SecurityManager as the active
 * SecurityManager.
 */
public class SubprocessSecurityManager extends SecurityManager {

    public static final Log LOG = LogFactory.getLog(SubprocessSecurityManager.class.getName());

    private SecurityManager parentSecurityManager;
    private boolean installed;
    private boolean allowReplacement;

    public SubprocessSecurityManager() {
        this.installed = false;
        this.allowReplacement = false;
    }

    /**
     * Install this SecurityManager and retain a reference to any
     * previously-installed SecurityManager.
     */
    public void install() {
        LOG.debug("Installing subprocess security manager");
        this.parentSecurityManager = System.getSecurityManager();
        System.setSecurityManager(this);
        this.installed = true;
    }

    /**
     * Restore an existing SecurityManager, uninstalling this one.
     */
    public void uninstall() {
        if (this.installed) {
            LOG.debug("Uninstalling subprocess security manager");
            this.allowReplacement = true;
            System.setSecurityManager(this.parentSecurityManager);
        }
    }

    @Override
    /**
     * Disallow the capability to call System.exit() or otherwise
     * terminate the JVM.
     */
    public void checkExit(int status) {
        LOG.debug("Rejecting System.exit call with status=" + status);
        throw new ExitSecurityException(status);
    }

    @Override
    /**
     * Check a particular permission. Checks with this SecurityManager
     * as well as any previously-installed manager.
     *
     * @param perm the Permission to check; must not be null.
     */
    public void checkPermission(Permission perm) {
        if (null != this.parentSecurityManager) {
            // Check if the prior SecurityManager would have rejected this.
            parentSecurityManager.checkPermission(perm);
        }

        if (!allowReplacement && perm.getName().equals("setSecurityManager")) {
            throw new SecurityException("Cannot replace security manager");
        }
    }

}