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.nio.ByteBuffer;
  41: import java.util.HashMap;
  42: 
  43: /**
  44:  * A Secure Class Loader for loading classes with additional
  45:  * support for specifying code source and permissions when
  46:  * they are retrieved by the system policy handler.
  47:  *
  48:  * @since 1.2
  49:  *
  50:  * @author Mark Benvenuto
  51:  */
  52: public class SecureClassLoader extends ClassLoader
  53: {
  54:   private final HashMap<CodeSource,ProtectionDomain> protectionDomainCache
  55:     = new HashMap<CodeSource, ProtectionDomain>();
  56: 
  57:   protected SecureClassLoader(ClassLoader parent)
  58:   {
  59:     super(parent);
  60:   }
  61: 
  62:   protected SecureClassLoader()
  63:   {
  64:   }
  65: 
  66:   /**
  67:    * Creates a class using an array of bytes and a
  68:    * CodeSource.
  69:    *
  70:    * @param name the name to give the class.  null if unknown.
  71:    * @param b the data representing the classfile, in classfile format.
  72:    * @param off the offset into the data where the classfile starts.
  73:    * @param len the length of the classfile data in the array.
  74:    * @param cs the CodeSource for the class or null when unknown.
  75:    *
  76:    * @return the class that was defined and optional CodeSource.
  77:    *
  78:    * @exception ClassFormatError if the byte array is not in proper classfile format.
  79:    */
  80:   protected final Class<?> defineClass(String name, byte[] b, int off, int len,
  81:                                     CodeSource cs)
  82:   {
  83:     return super.defineClass(name, b, off, len, getProtectionDomain(cs));
  84:   }
  85: 
  86:   /**
  87:    * Creates a class using an ByteBuffer and a
  88:    * CodeSource.
  89:    *
  90:    * @param name the name to give the class.  null if unknown.
  91:    * @param b the data representing the classfile, in classfile format.
  92:    * @param cs the CodeSource for the class or null when unknown.
  93:    *
  94:    * @return the class that was defined and optional CodeSource.
  95:    *
  96:    * @exception ClassFormatError if the byte array is not in proper classfile format.
  97:    *
  98:    * @since 1.5
  99:    */
 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: }