001/* SecureClassLoader.java --- A Secure Class Loader 002 Copyright (C) 1999, 2004, 2006 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038package java.security; 039 040import java.nio.ByteBuffer; 041import 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 */ 052public 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}