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.util.WeakHashMap;
041
042 import java.nio.ByteBuffer;
043 import java.util.HashMap;
044
045 /**
046 * A Secure Class Loader for loading classes with additional
047 * support for specifying code source and permissions when
048 * they are retrieved by the system policy handler.
049 *
050 * @since 1.2
051 *
052 * @author Mark Benvenuto
053 */
054 public class SecureClassLoader extends ClassLoader
055 {
056 private final HashMap<CodeSource,ProtectionDomain> protectionDomainCache
057 = new HashMap<CodeSource, ProtectionDomain>();
058
059 protected SecureClassLoader(ClassLoader parent)
060 {
061 super(parent);
062 }
063
064 protected SecureClassLoader()
065 {
066 }
067
068 /**
069 * Creates a class using an array of bytes and a
070 * CodeSource.
071 *
072 * @param name the name to give the class. null if unknown.
073 * @param b the data representing the classfile, in classfile format.
074 * @param off the offset into the data where the classfile starts.
075 * @param len the length of the classfile data in the array.
076 * @param cs the CodeSource for the class or null when unknown.
077 *
078 * @return the class that was defined and optional CodeSource.
079 *
080 * @exception ClassFormatError if the byte array is not in proper classfile format.
081 */
082 protected final Class<?> defineClass(String name, byte[] b, int off, int len,
083 CodeSource cs)
084 {
085 return super.defineClass(name, b, off, len, getProtectionDomain(cs));
086 }
087
088 /**
089 * Creates a class using an ByteBuffer and a
090 * CodeSource.
091 *
092 * @param name the name to give the class. null if unknown.
093 * @param b the data representing the classfile, in classfile format.
094 * @param cs the CodeSource for the class or null when unknown.
095 *
096 * @return the class that was defined and optional CodeSource.
097 *
098 * @exception ClassFormatError if the byte array is not in proper classfile format.
099 *
100 * @since 1.5
101 */
102 protected final Class<?> defineClass(String name, ByteBuffer b, CodeSource cs)
103 {
104 return super.defineClass(name, b, getProtectionDomain(cs));
105 }
106
107 /* Lookup or create a protection domain for the CodeSource,
108 * if CodeSource is null it will return null. */
109 private ProtectionDomain getProtectionDomain(CodeSource cs)
110 {
111 ProtectionDomain protectionDomain = null;
112 if (cs != null)
113 {
114 synchronized (protectionDomainCache)
115 {
116 protectionDomain = (ProtectionDomain)protectionDomainCache.get(cs);
117 }
118
119 if (protectionDomain == null)
120 {
121 protectionDomain
122 = new ProtectionDomain(cs, getPermissions(cs), this, null);
123 synchronized (protectionDomainCache)
124 {
125 ProtectionDomain domain
126 = (ProtectionDomain)protectionDomainCache.get(cs);
127 if (domain == null)
128 protectionDomainCache.put(cs, protectionDomain);
129 else
130 protectionDomain = domain;
131 }
132 }
133 }
134 return protectionDomain;
135 }
136
137 /**
138 * Returns a PermissionCollection for the specified CodeSource.
139 * The default implementation invokes
140 * java.security.Policy.getPermissions.
141 *
142 * This method is called by defineClass that takes a CodeSource
143 * argument to build a proper ProtectionDomain for the class
144 * being defined.
145 */
146 protected PermissionCollection getPermissions(CodeSource cs)
147 {
148 Policy policy = Policy.getCurrentPolicy();
149 return policy.getPermissions(cs);
150 }
151 }