Prevent drag-and-drop events from firing over cross-site, same-page frames.

content/browser/web_contents/web_contents_view_aura.cc

Index: content/browser/web_contents/web_contents_view_aura.cc
diff --git a/content/browser/web_contents/web_contents_view_aura.cc b/content/browser/web_contents/web_contents_view_aura.cc
index 709ea5dd5d1cbccdfe063040cbdc20419c3638c7..fa90e5e4b55a878e9a3b49667a6e762e121d2cb4 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -6,6 +6,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <utility>

[Charlie Reis, 2016/12/14 18:06:50]

Might not need this if we use GlobalRoutingID.

 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
@@ -400,6 +401,10 @@ int ConvertAuraEventFlagsToWebInputEventModifiers(int aura_event_flags) {
   return web_input_event_modifiers;
 }
 
+std::pair<int, int> GetRenderViewHostID(RenderViewHost* rvh) {
+  return std::make_pair(rvh->GetProcess()->GetID(), rvh->GetRoutingID());
+}
+
 }  // namespace
 
 class WebContentsViewAura::WindowObserver
@@ -515,7 +520,9 @@ WebContentsViewAura::WebContentsViewAura(WebContentsImpl* web_contents,
       delegate_(delegate),
       current_drag_op_(blink::WebDragOperationNone),
       drag_dest_delegate_(nullptr),
-      current_rvh_for_drag_(nullptr),
+      current_rvh_for_drag_(-1, -1),

[lfg, 2016/12/14 16:10:09]

You should use kInvalidUniqueID for invalid process ids, and MSG_ROUTING_NONE
for invalid routing IDs.

+      drag_source_rph_(-1),
+      drag_source_rvh_(-1, -1),
       current_overscroll_gesture_(OVERSCROLL_NONE),
       completed_overscroll_gesture_(OVERSCROLL_NONE),
       navigation_overlay_(nullptr),
@@ -552,6 +559,9 @@ void WebContentsViewAura::SizeChangedCommon(const gfx::Size& size) {
 
 void WebContentsViewAura::EndDrag(RenderWidgetHost* source_rwh,
                                   blink::WebDragOperationsMask ops) {
+  drag_source_rph_ = -1;

[lfg, 2016/12/14 16:10:09]

kInvalidUniqueID

+  drag_source_rvh_ = std::make_pair(-1, -1);

[lfg, 2016/12/14 16:10:09]

kInvalidUniqueID, MSG_ROUTING_NONE.

+
   if (!web_contents_)
     return;
 
@@ -563,8 +573,8 @@ void WebContentsViewAura::EndDrag(RenderWidgetHost* source_rwh,
   if (screen_position_client)
     screen_position_client->ConvertPointFromScreen(window, &client_loc);
 
-  // TODO(paulmeyer): In the OOPIF case, should |client_loc| be converted to
-  // the coordinates local to |drag_start_rwh_|? See crbug.com/647249.
+  // TODO(paulmeyer): In the OOPIF case, should |client_loc| be converted to the
+  // coordinates local to |source_rwh|? See crbug.com/647249.
   web_contents_->DragSourceEndedAt(client_loc.x(), client_loc.y(),
                                    screen_loc.x(), screen_loc.y(), ops,
                                    source_rwh);
@@ -629,6 +639,13 @@ gfx::NativeView WebContentsViewAura::GetRenderWidgetHostViewParent() const {
   return window_.get();
 }
 
+bool WebContentsViewAura::ValidDragTarget(
+    RenderWidgetHostImpl* target_rwh) const {
+  return target_rwh->GetProcess()->GetID() == drag_source_rph_ ||

[Charlie Reis, 2016/12/14 18:06:50]

Please put a comment explaining what this is trying to check, since it's a bit
subtle.  Something like:

Allow the drag if it's within the same process (in which case Blink will
validate it), or if it's between different pages.  Do not allow cross-process
drags within the same page.

[Charlie Reis, 2016/12/14 18:36:36]

I think you missed this comment, which I think is worthwhile because of the
Blink validation part.

[paulmeyer, 2016/12/14 18:53:18]

Oh sorry, I meant to reply that the comment is already on this function in the
header.

+      GetRenderViewHostID(web_contents_->GetRenderViewHost()) !=
+      drag_source_rvh_;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // WebContentsViewAura, WebContentsView implementation:
 
@@ -907,6 +924,9 @@ void WebContentsViewAura::StartDragging(
   base::WeakPtr<RenderWidgetHostImpl> source_rwh_weak_ptr =
       source_rwh->GetWeakPtr();
 
+  drag_source_rph_ = source_rwh->GetProcess()->GetID();
+  drag_source_rvh_ = GetRenderViewHostID(web_contents_->GetRenderViewHost());
+
   ui::TouchSelectionController* selection_controller = GetSelectionController();
   if (selection_controller)
     selection_controller->HideAndDisallowShowingAutomatically();
@@ -1130,12 +1150,17 @@ void WebContentsViewAura::OnMouseEvent(ui::MouseEvent* event) {
 
 void WebContentsViewAura::OnDragEntered(const ui::DropTargetEvent& event) {
   gfx::Point transformed_pt;
-  current_rwh_for_drag_ =
+  RenderWidgetHostImpl* target_rwh =
       web_contents_->GetInputEventRouter()->GetRenderWidgetHostAtPoint(
           web_contents_->GetRenderViewHost()->GetWidget()->GetView(),
-          event.location(), &transformed_pt)->GetWeakPtr();
-  current_rvh_for_drag_ = web_contents_->GetRenderViewHost();
+          event.location(), &transformed_pt);
+
+  if (!ValidDragTarget(target_rwh))
+    return;
 
+  current_rwh_for_drag_ = target_rwh->GetWeakPtr();
+  current_rvh_for_drag_ =
+      GetRenderViewHostID(web_contents_->GetRenderViewHost());
   current_drop_data_.reset(new DropData());
   PrepareDropData(current_drop_data_.get(), event.data());
   current_rwh_for_drag_->FilterDropData(current_drop_data_.get());
@@ -1171,6 +1196,9 @@ int WebContentsViewAura::OnDragUpdated(const ui::DropTargetEvent& event) {
           web_contents_->GetRenderViewHost()->GetWidget()->GetView(),
           event.location(), &transformed_pt);
 
+  if (!ValidDragTarget(target_rwh))
+    return ui::DragDropTypes::DRAG_NONE;
+
   if (target_rwh != current_rwh_for_drag_.get()) {
     if (current_rwh_for_drag_)
       current_rwh_for_drag_->DragTargetDragLeave();
@@ -1193,7 +1221,8 @@ int WebContentsViewAura::OnDragUpdated(const ui::DropTargetEvent& event) {
 }
 
 void WebContentsViewAura::OnDragExited() {
-  if (current_rvh_for_drag_ != web_contents_->GetRenderViewHost() ||
+  if (current_rvh_for_drag_ !=
+      GetRenderViewHostID(web_contents_->GetRenderViewHost()) ||
       !current_drop_data_) {
     return;
   }
@@ -1216,6 +1245,9 @@ int WebContentsViewAura::OnPerformDrop(const ui::DropTargetEvent& event) {
           web_contents_->GetRenderViewHost()->GetWidget()->GetView(),
           event.location(), &transformed_pt);
 
+  if (!ValidDragTarget(target_rwh))
+    return ui::DragDropTypes::DRAG_NONE;
+
   if (target_rwh != current_rwh_for_drag_.get()) {
     if (current_rwh_for_drag_)
       current_rwh_for_drag_->DragTargetDragLeave();