Source for java.security.SecureClassLoader

 1:  /* SecureClassLoader.java --- A Secure Class Loader
 2:  Copyright (C) 1999, 2004, 2006 Free Software Foundation, Inc.
 3: 
 4: This file is part of GNU Classpath.
 5: 
 6: GNU Classpath is free software; you can redistribute it and/or modify
 7: it under the terms of the GNU General Public License as published by
 8: the Free Software Foundation; either version 2, or (at your option)
 9: any later version.
 10: 
 11: GNU Classpath is distributed in the hope that it will be useful, but
 12: WITHOUT ANY WARRANTY; without even the implied warranty of
 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 14: General Public License for more details.
 15: 
 16: You should have received a copy of the GNU General Public License
 17: along with GNU Classpath; see the file COPYING. If not, write to the
 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 19: 02110-1301 USA.
 20: 
 21: Linking this library statically or dynamically with other modules is
 22: making a combined work based on this library. Thus, the terms and
 23: conditions of the GNU General Public License cover the whole
 24: combination.
 25: 
 26: As a special exception, the copyright holders of this library give you
 27: permission to link this library with independent modules to produce an
 28: executable, regardless of the license terms of these independent
 29: modules, and to copy and distribute the resulting executable under
 30: terms of your choice, provided that you also meet, for each linked
 31: independent module, the terms and conditions of the license of that
 32: module. An independent module is a module which is not derived from
 33: or based on this library. If you modify this library, you may extend
 34: this exception to your version of the library, but you are not
 35: obligated to do so. If you do not wish to do so, delete this
 36: exception statement from your version. */
 37: 
 38:  package java.security;
 39: 
 40:  import java.util.WeakHashMap;
 41: 
 42:  import java.nio.ByteBuffer;
 43:  import java.util.HashMap;
 44: 
 45:  /**
 46:  * A Secure Class Loader for loading classes with additional 
 47:  * support for specifying code source and permissions when
 48:  * they are retrieved by the system policy handler.
 49:  *
 50:  * @since 1.2
 51:  *
 52:  * @author Mark Benvenuto
 53:  */
 54:  public class SecureClassLoader extends ClassLoader
 55: {
 56:  private final HashMap<CodeSource,ProtectionDomain> protectionDomainCache
 57:  = new HashMap<CodeSource, ProtectionDomain>();
 58: 
 59:  protected SecureClassLoader(ClassLoader parent)
 60:  {
 61:  super(parent);
 62:  }
 63: 
 64:  protected SecureClassLoader()
 65:  {
 66:  }
 67: 
 68:  /** 
 69:  * Creates a class using an array of bytes and a 
 70:  * CodeSource.
 71:  *
 72:  * @param name the name to give the class. null if unknown.
 73:  * @param b the data representing the classfile, in classfile format.
 74:  * @param off the offset into the data where the classfile starts.
 75:  * @param len the length of the classfile data in the array.
 76:  * @param cs the CodeSource for the class or null when unknown.
 77:  *
 78:  * @return the class that was defined and optional CodeSource.
 79:  *
 80:  * @exception ClassFormatError if the byte array is not in proper classfile format.
 81:  */
 82:  protected final Class<?> defineClass(String name, byte[] b, int off, int len,
 83:  CodeSource cs)
 84:  {
 85:  return super.defineClass(name, b, off, len, getProtectionDomain(cs));
 86:  }
 87: 
 88:  /** 
 89:  * Creates a class using an ByteBuffer and a 
 90:  * CodeSource.
 91:  *
 92:  * @param name the name to give the class. null if unknown.
 93:  * @param b the data representing the classfile, in classfile format.
 94:  * @param cs the CodeSource for the class or null when unknown.
 95:  *
 96:  * @return the class that was defined and optional CodeSource.
 97:  *
 98:  * @exception ClassFormatError if the byte array is not in proper classfile format.
 99:  *
 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: }