1 /*
   2  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.security;
  27 
  28 import java.util.HashMap;
  29 import java.util.ArrayList;
  30 import java.net.URL;
  31 
  32 import sun.security.util.Debug;
  33 
  34 /**
  35  * This class extends ClassLoader with additional support for defining
  36  * classes with an associated code source and permissions which are
  37  * retrieved by the system policy by default.
  38  *
  39  * @author  Li Gong
  40  * @author  Roland Schemers
  41  */
  42 public class SecureClassLoader extends ClassLoader {
  43     /*
  44      * If initialization succeed this is set to true and security checks will
  45      * succeed. Otherwise the object is not initialized and the object is
  46      * useless.
  47      */
  48     private final boolean initialized;
  49 
  50     // HashMap that maps CodeSource to ProtectionDomain
  51     // @GuardedBy("pdcache")
  52     private final HashMap<CodeSource, ProtectionDomain> pdcache =
  53                         new HashMap<>(11);
  54 
  55     private static final Debug debug = Debug.getInstance("scl");
  56 
  57     static {
  58         ClassLoader.registerAsParallelCapable();
  59     }
  60 
  61     /**
  62      * Creates a new SecureClassLoader using the specified parent
  63      * class loader for delegation.
  64      *
  65      * <p>If there is a security manager, this method first
  66      * calls the security manager's {@code checkCreateClassLoader}
  67      * method  to ensure creation of a class loader is allowed.
  68      * <p>
  69      * @param parent the parent ClassLoader
  70      * @exception  SecurityException  if a security manager exists and its
  71      *             {@code checkCreateClassLoader} method doesn't allow
  72      *             creation of a class loader.
  73      * @see SecurityManager#checkCreateClassLoader
  74      */
  75     protected SecureClassLoader(ClassLoader parent) {
  76         super(parent);
  77         // this is to make the stack depth consistent with 1.1
  78         SecurityManager security = System.getSecurityManager();
  79         if (security != null) {
  80             security.checkCreateClassLoader();
  81         }
  82         initialized = true;
  83     }
  84 
  85     /**
  86      * Creates a new SecureClassLoader using the default parent class
  87      * loader for delegation.
  88      *
  89      * <p>If there is a security manager, this method first
  90      * calls the security manager's {@code checkCreateClassLoader}
  91      * method  to ensure creation of a class loader is allowed.
  92      *
  93      * @exception  SecurityException  if a security manager exists and its
  94      *             {@code checkCreateClassLoader} method doesn't allow
  95      *             creation of a class loader.
  96      * @see SecurityManager#checkCreateClassLoader
  97      */
  98     protected SecureClassLoader() {
  99         super();
 100         // this is to make the stack depth consistent with 1.1
 101         SecurityManager security = System.getSecurityManager();
 102         if (security != null) {
 103             security.checkCreateClassLoader();
 104         }
 105         initialized = true;
 106     }
 107 
 108     /**
 109      * Converts an array of bytes into an instance of class Class,
 110      * with an optional CodeSource. Before the
 111      * class can be used it must be resolved.
 112      * <p>
 113      * If a non-null CodeSource is supplied a ProtectionDomain is
 114      * constructed and associated with the class being defined.
 115      * <p>
 116      * @param      name the expected name of the class, or {@code null}
 117      *                  if not known, using '.' and not '/' as the separator
 118      *                  and without a trailing ".class" suffix.
 119      * @param      b    the bytes that make up the class data. The bytes in
 120      *             positions {@code off} through {@code off+len-1}
 121      *             should have the format of a valid class file as defined by
 122      *             <cite>The Java&trade; Virtual Machine Specification</cite>.
 123      * @param      off  the start offset in {@code b} of the class data
 124      * @param      len  the length of the class data
 125      * @param      cs   the associated CodeSource, or {@code null} if none
 126      * @return the {@code Class} object created from the data,
 127      *         and optional CodeSource.
 128      * @exception  ClassFormatError if the data did not contain a valid class
 129      * @exception  IndexOutOfBoundsException if either {@code off} or
 130      *             {@code len} is negative, or if
 131      *             {@code off+len} is greater than {@code b.length}.
 132      *
 133      * @exception  SecurityException if an attempt is made to add this class
 134      *             to a package that contains classes that were signed by
 135      *             a different set of certificates than this class, or if
 136      *             the class name begins with "java.".
 137      */
 138     protected final Class<?> defineClass(String name,
 139                                          byte[] b, int off, int len,
 140                                          CodeSource cs)
 141     {
 142         return defineClass(name, b, off, len, getProtectionDomain(cs));
 143     }
 144 
 145     /**
 146      * Converts a {@link java.nio.ByteBuffer ByteBuffer}
 147      * into an instance of class {@code Class}, with an optional CodeSource.
 148      * Before the class can be used it must be resolved.
 149      * <p>
 150      * If a non-null CodeSource is supplied a ProtectionDomain is
 151      * constructed and associated with the class being defined.
 152      * <p>
 153      * @param      name the expected name of the class, or {@code null}
 154      *                  if not known, using '.' and not '/' as the separator
 155      *                  and without a trailing ".class" suffix.
 156      * @param      b    the bytes that make up the class data.  The bytes from positions
 157      *                  {@code b.position()} through {@code b.position() + b.limit() -1}
 158      *                  should have the format of a valid class file as defined by
 159      *                  <cite>The Java&trade; Virtual Machine Specification</cite>.
 160      * @param      cs   the associated CodeSource, or {@code null} if none
 161      * @return the {@code Class} object created from the data,
 162      *         and optional CodeSource.
 163      * @exception  ClassFormatError if the data did not contain a valid class
 164      * @exception  SecurityException if an attempt is made to add this class
 165      *             to a package that contains classes that were signed by
 166      *             a different set of certificates than this class, or if
 167      *             the class name begins with "java.".
 168      *
 169      * @since  1.5
 170      */
 171     protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
 172                                          CodeSource cs)
 173     {
 174         return defineClass(name, b, getProtectionDomain(cs));
 175     }
 176 
 177     /**
 178      * Returns the permissions for the given CodeSource object.
 179      * <p>
 180      * This method is invoked by the defineClass method which takes
 181      * a CodeSource as an argument when it is constructing the
 182      * ProtectionDomain for the class being defined.
 183      * <p>
 184      * @param codesource the codesource.
 185      *
 186      * @return the permissions granted to the codesource.
 187      *
 188      */
 189     protected PermissionCollection getPermissions(CodeSource codesource)
 190     {
 191         check();
 192         return new Permissions(); // ProtectionDomain defers the binding
 193     }
 194 
 195     /*
 196      * Returned cached ProtectionDomain for the specified CodeSource.
 197      */
 198     private ProtectionDomain getProtectionDomain(CodeSource cs) {
 199         if (cs == null)
 200             return null;
 201 
 202         ProtectionDomain pd = null;
 203         synchronized (pdcache) {
 204             pd = pdcache.get(cs);
 205             if (pd == null) {
 206                 PermissionCollection perms = getPermissions(cs);
 207                 pd = new ProtectionDomain(cs, perms, this, null);
 208                 pdcache.put(cs, pd);
 209                 if (debug != null) {
 210                     debug.println(" getPermissions "+ pd);
 211                     debug.println("");
 212                 }
 213             }
 214         }
 215         return pd;
 216     }
 217 
 218     // Used by the VM to create the ProtectionDomain for the url. Assumes
 219     // that the url points to an unsigned code source.
 220     private ProtectionDomain getProtectionDomain(URL url) {
 221         CodeSigner[] signers = null;
 222         CodeSource cs = new CodeSource(url, signers);
 223 
 224         return getProtectionDomain(cs);
 225     }
 226 
 227     /*
 228      * Check to make sure the class loader has been initialized.
 229      */
 230     private void check() {
 231         if (!initialized) {
 232             throw new SecurityException("ClassLoader object not initialized");
 233         }
 234     }
 235 
 236 }