[cp-patches] FYI: Disallow unsecure copy/paste exchange

[Mark Wielaard]

Hi,

After the last discussion about TransferHandler and security issues it
seemed safer to me to just disallow any copy/paste between untrusted
code paths as was suggested earlier.

2005-12-04  Mark Wielaard  <address@hidden>

        * javax/swing/TransferHandler
        (TransferAction.actionPerformed): Beep and return when clipboard
        is null.
        (getClipboard): Return null when access denied.
        (clipboard): Removed static field.

Committed,

Mark

Index: javax/swing/TransferHandler.java
===================================================================
RCS file: /cvsroot/classpath/classpath/javax/swing/TransferHandler.java,v
retrieving revision 1.12
diff -u -r1.12 TransferHandler.java
--- javax/swing/TransferHandler.java    22 Nov 2005 16:07:57 -0000      1.12
+++ javax/swing/TransferHandler.java    4 Dec 2005 19:50:34 -0000
@@ -1,5 +1,5 @@
 /* TransferHandler.java --
-   Copyright (C) 2004 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2005 Free Software Foundation, Inc.
 
 This file is part of GNU Classpath.
 
@@ -43,6 +43,7 @@
 import java.awt.datatransfer.Transferable;
 import java.awt.event.ActionEvent;
 import java.awt.event.InputEvent;
+import java.awt.Toolkit;
 import java.io.Serializable;
 
 public class TransferHandler implements Serializable
@@ -62,6 +63,13 @@
       TransferHandler transferHandler = component.getTransferHandler();
       Clipboard clipboard = getClipboard(component);
 
+      if (clipboard == null)
+       {
+         // Access denied!
+         Toolkit.getDefaultToolkit().beep();
+         return;
+       }
+
       if (command.equals(COMMAND_COPY))
        transferHandler.exportToClipboard(component, clipboard, COPY);
       else if (command.equals(COMMAND_CUT))
@@ -76,8 +84,8 @@
     }
   
     /**
-     * Get the system cliboard. If not available, create and return the 
VM-local
-     * clipboard.
+     * Get the system cliboard or null if the caller isn't allowed to
+     * access the system clipboard.
      * 
      * @param component a component, used to get the toolkit.
      * @return the clipboard
@@ -85,22 +93,13 @@
     private static Clipboard getClipboard(JComponent component)
     {
       try
-        {
-          SecurityManager sm = System.getSecurityManager();
-          if (sm != null)
-            sm.checkSystemClipboardAccess();
-
-          // We may access the system clipboard.
-          return component.getToolkit().getSystemClipboard();
-        }
-      catch (Exception e)
-        {
-          // We may not access system clipboard.
-          // Create VM-local clipboard if none exists yet.
-          if (clipboard == null)
-            clipboard = new Clipboard("Clipboard");
-          return clipboard;
-        }
+       {
+         return component.getToolkit().getSystemClipboard();
+       }
+      catch (SecurityException se)
+       {
+         return null;
+       }
     }
   }
   
@@ -118,12 +117,6 @@
   private static Action copyAction = new TransferAction(COMMAND_COPY);
   private static Action cutAction = new TransferAction(COMMAND_CUT);
   private static Action pasteAction = new TransferAction(COMMAND_PASTE);
-  
-  /**
-   * Clipboard if system clipboard may not be used.
-   * Package-private to avoid an accessor method.
-   */
-  static Clipboard clipboard;
   
   private int sourceActions;
   private Icon visualRepresentation;

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