1 /*
   2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 import java.security.AccessController;
  25 import java.security.Permission;
  26 import java.security.Policy;
  27 import java.security.PrivilegedAction;
  28 import java.security.ProtectionDomain;
  29 
  30 public class CustomPolicy extends Policy {
  31 
  32     // the ProtectionDomain of CustomPolicy
  33     private final ProtectionDomain policyPd;
  34 
  35     public CustomPolicy() {
  36         policyPd = AccessController.doPrivileged(
  37             (PrivilegedAction<ProtectionDomain>)
  38                 () -> this.getClass().getProtectionDomain());
  39     }
  40 
  41     @Override
  42     public boolean implies(ProtectionDomain pd, Permission perm) {
  43         System.out.println("CustomPolicy.implies");
  44 
  45         // If the protection domain is the same as CustomPolicy, then
  46         // we return true. This is to prevent recursive permission checks
  47         // that lead to StackOverflow errors when the policy implementation
  48         // performs a sensitive operation that triggers a permission check,
  49         // for example, as below.
  50         if (pd == policyPd) {
  51             return true;
  52         }
  53 
  54         // Do something that triggers a permission check to make sure that
  55         // we don't cause a StackOverflow error.
  56         String home = AccessController.doPrivileged(
  57             (PrivilegedAction<String>) () -> System.getProperty("user.home"));
  58 
  59         return true;
  60     }
  61 }