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 }