001 /* SecureClassLoader.java --- A Secure Class Loader
002 Copyright (C) 1999, 2004, 2006 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package java.security;
039
040 import java.nio.ByteBuffer;
041 import java.util.HashMap;
042
043 /**
044 * A Secure Class Loader for loading classes with additional
045 * support for specifying code source and permissions when
046 * they are retrieved by the system policy handler.
047 *
048 * @since 1.2
049 *
050 * @author Mark Benvenuto
051 */
052 public class SecureClassLoader extends ClassLoader
053 {
054 private final HashMap<CodeSource,ProtectionDomain> protectionDomainCache
055 = new HashMap<CodeSource, ProtectionDomain>();
056
057 protected SecureClassLoader(ClassLoader parent)
058 {
059 super(parent);
060 }
061
062 protected SecureClassLoader()
063 {
064 }
065
066 /**
067 * Creates a class using an array of bytes and a
068 * CodeSource.
069 *
070 * @param name the name to give the class. null if unknown.
071 * @param b the data representing the classfile, in classfile format.
072 * @param off the offset into the data where the classfile starts.
073 * @param len the length of the classfile data in the array.
074 * @param cs the CodeSource for the class or null when unknown.
075 *
076 * @return the class that was defined and optional CodeSource.
077 *
078 * @exception ClassFormatError if the byte array is not in proper classfile format.
079 */
080 protected final Class<?> defineClass(String name, byte[] b, int off, int len,
081 CodeSource cs)
082 {
083 return super.defineClass(name, b, off, len, getProtectionDomain(cs));
084 }
085
086 /**
087 * Creates a class using an ByteBuffer and a
088 * CodeSource.
089 *
090 * @param name the name to give the class. null if unknown.
091 * @param b the data representing the classfile, in classfile format.
092 * @param cs the CodeSource for the class or null when unknown.
093 *
094 * @return the class that was defined and optional CodeSource.
095 *
096 * @exception ClassFormatError if the byte array is not in proper classfile format.
097 *
098 * @since 1.5
099 */
100 protected final Class<?> defineClass(String name, ByteBuffer b, CodeSource cs)
101 {
102 return super.defineClass(name, b, getProtectionDomain(cs));
103 }
104
105 /* Lookup or create a protection domain for the CodeSource,
106 * if CodeSource is null it will return null. */
107 private ProtectionDomain getProtectionDomain(CodeSource cs)
108 {
109 ProtectionDomain protectionDomain = null;
110 if (cs != null)
111 {
112 synchronized (protectionDomainCache)
113 {
114 protectionDomain = protectionDomainCache.get(cs);
115 }
116
117 if (protectionDomain == null)
118 {
119 protectionDomain
120 = new ProtectionDomain(cs, getPermissions(cs), this, null);
121 synchronized (protectionDomainCache)
122 {
123 ProtectionDomain domain = protectionDomainCache.get(cs);
124 if (domain == null)
125 protectionDomainCache.put(cs, protectionDomain);
126 else
127 protectionDomain = domain;
128 }
129 }
130 }
131 return protectionDomain;
132 }
133
134 /**
135 * Returns a PermissionCollection for the specified CodeSource.
136 * The default implementation invokes
137 * java.security.Policy.getPermissions.
138 *
139 * This method is called by defineClass that takes a CodeSource
140 * argument to build a proper ProtectionDomain for the class
141 * being defined.
142 */
143 protected PermissionCollection getPermissions(CodeSource cs)
144 {
145 Policy policy = Policy.getCurrentPolicy();
146 return policy.getPermissions(cs);
147 }
148 }