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 }