CheckRestrictedPackage.java

/*
 * Copyright (c) 2010, 2021, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file, and Oracle licenses the original version of this file under the BSD
 * license:
 */
/*
   Copyright 2009-2013 Attila Szegedi

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are
   met:
   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
   * 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.
   * Neither the name of the copyright holder nor the names of
     contributors may be used to endorse or promote products derived from
     this software without specific prior written permission.

   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 COPYRIGHT HOLDER
   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 jdk.dynalink.beans;

import java.lang.reflect.Modifier;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import jdk.dynalink.internal.AccessControlContextFactory;

/**
 * A utility class to check whether a given class is in a package with restricted access e.g. "sun.*" etc.
 */
class CheckRestrictedPackage {
    @SuppressWarnings("removal")
    private static final AccessControlContext NO_PERMISSIONS_CONTEXT =
            AccessControlContextFactory.createAccessControlContext();

    /**
     * Returns true if the class is either not public, or it resides in a package with restricted access.
     * @param clazz the class to test
     * @return true if the class is either not public, or it resides in a package with restricted access.
     */
    @SuppressWarnings("removal")
    static boolean isRestrictedClass(final Class<?> clazz) {
        if(!Modifier.isPublic(clazz.getModifiers())) {
            // Non-public classes are always restricted
            return true;
        }
        final String name = clazz.getName();
        final int i = name.lastIndexOf('.');
        if (i == -1) {
            // Classes in default package are never restricted
            return false;
        }
        final String pkgName = name.substring(0, i);
        final Module module = clazz.getModule();
        if (module != null && !module.isExported(pkgName)) {
            // Classes in unexported packages of modules are always restricted
            return true;
        }

        final SecurityManager sm = System.getSecurityManager();
        if(sm == null) {
            // No further restrictions if we don't have a security manager
            return false;
        }
        // Do a package access check from within an access control context with no permissions
        try {
            AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
                sm.checkPackageAccess(pkgName);
                return null;
            }, NO_PERMISSIONS_CONTEXT);
        } catch(final SecurityException e) {
            return true;
        }
        return false;
    }
}