Added impersonation of the anonymous token around CloseClipboard

ui/base/clipboard/clipboard_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Many of these functions are based on those found in
 // webkit/port/platform/PasteboardWin.cpp
 
 #include "ui/base/clipboard/clipboard_win.h"
 
 #include <shellapi.h>
@@ skipping 17 matching lines @@
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/base/clipboard/clipboard_util_win.h"
 #include "ui/base/clipboard/custom_data_helper.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/size.h"
 
 namespace ui {
 
 namespace {
 
+// A scoper to impersonate the anonymous token and revert when leaving scope
+class AnonymousImpersonator {
+ public:
+  AnonymousImpersonator() {
+    must_revert_ = ::ImpersonateAnonymousToken(::GetCurrentThread());
+  }
+
+  ~AnonymousImpersonator() {
+    if (must_revert_)
+      ::RevertToSelf();
+  }
+
+ private:
+  BOOL must_revert_;

[dcheng, 2014/12/13 01:16:50]

Actually, you probably want DISALLOW_COPY_AND_ASSIGN here, just in case.

+};
+
 // A scoper to manage acquiring and automatically releasing the clipboard.
 class ScopedClipboard {
  public:
   ScopedClipboard() : opened_(false) { }
 
   ~ScopedClipboard() {
     if (opened_)
       Release();
   }
 
@@ skipping 29 matching lines @@
         return true;
       }
     }
 
     // We failed to acquire the clipboard.
     return false;
   }
 
   void Release() {
     if (opened_) {
+      // Impersonate the anonymous token during the call to CloseClipboard
+      // This prevents Windows 8+ capturing the broker's access token which
+      // could be accessed by lower-privileges chrome processes leading to
+      // a risk of EoP
+      AnonymousImpersonator impersonator;
       ::CloseClipboard();
       opened_ = false;
     } else {
       NOTREACHED();
     }
   }
 
  private:
   bool opened_;
 };
@@ skipping 756 matching lines @@
   if (!clipboard_owner_)
     return NULL;
 
   if (clipboard_owner_->hwnd() == NULL)
     clipboard_owner_->Create(base::Bind(&ClipboardOwnerWndProc));
 
   return clipboard_owner_->hwnd();
 }
 
 }  // namespace ui