DLP: Disallow Drop if not allowed

Changed DragDropController to:
- Cancel drop if not allowed by policy rules.
- Show CursorType::NoDrop while dragging if
the policy rules disallow the data from being
dropped.

Bug: 1139886
Change-Id: I8a12f1f4af2fa0f21d4d562d393d9f64cec39f72
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2595382Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Aya Elsayed <ayaelattar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842939}

ash/drag_drop/drag_drop_controller.cc

@@ -23,6 +23,8 @@
 #include "ui/aura/window_delegate.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/base/cursor/mojom/cursor_type.mojom-shared.h"
+#include "ui/base/data_transfer_policy/data_transfer_endpoint.h"
+#include "ui/base/data_transfer_policy/data_transfer_policy_controller.h"
 #include "ui/base/dragdrop/drag_drop_types.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/dragdrop/os_exchange_data_provider.h"
@@ -81,6 +83,19 @@ void DispatchGestureEndToWindow(aura::Window* window) {
   }
 }
 
+bool IsDragDropAllowed(const ui::OSExchangeData* drag_data,
+                       aura::client::DragUpdateInfo& drag_info,
+                       bool is_drop) {
+  DCHECK(drag_data);
+
+  drag_info.data_endpoint.set_notify_if_restricted(is_drop);
+
+  return ui::DataTransferPolicyController::HasInstance()
+             ? ui::DataTransferPolicyController::Get()->IsDragDropAllowed(
+                   drag_data->GetSource(), &drag_info.data_endpoint)
+             : true;
+}
+
 }  // namespace
 
 class DragDropTrackerDelegate : public aura::WindowDelegate {
@@ -464,14 +479,19 @@ void DragDropController::DragUpdate(aura::Window* target,
       e.set_flags(event.flags());
       ui::Event::DispatcherApi(&e).set_target(target);
       drag_info = delegate->OnDragUpdated(e);
+      bool is_drop_allowed = IsDragDropAllowed(drag_data_.get(), drag_info,
+                                               /*is_drop=*/false);
       gfx::NativeCursor cursor = ui::mojom::CursorType::kNoDrop;
+      if (is_drop_allowed) {
         if (drag_info.drag_operation & ui::DragDropTypes::DRAG_COPY)
           cursor = ui::mojom::CursorType::kCopy;
         else if (drag_info.drag_operation & ui::DragDropTypes::DRAG_LINK)
           cursor = ui::mojom::CursorType::kAlias;
         else if (drag_info.drag_operation & ui::DragDropTypes::DRAG_MOVE)
           cursor = ui::mojom::CursorType::kGrabbing;
-
+      } else {
+        drag_info.drag_operation = ui::DragDropTypes::DRAG_NONE;
+      }
       Shell::Get()->cursor_manager()->SetCursor(cursor);
     }
   }
@@ -506,8 +526,6 @@ void DragDropController::DragUpdate(aura::Window* target,
 
 void DragDropController::Drop(aura::Window* target,
                               const ui::LocatedEvent& event) {
-  Shell::Get()->cursor_manager()->SetCursor(ui::mojom::CursorType::kPointer);
-
   // We must guarantee that a target gets a OnDragEntered before Drop. WebKit
   // depends on not getting a Drop without DragEnter. This behavior is
   // consistent with drag/drop on other platforms.
@@ -515,6 +533,14 @@ void DragDropController::Drop(aura::Window* target,
     DragUpdate(target, event);
   DCHECK(target == drag_window_);
 
+  if (!IsDragDropAllowed(drag_data_.get(), current_drag_info_,
+                         /*is_drop=*/true)) {
+    DragCancel();
+    return;
+  }
+
+  Shell::Get()->cursor_manager()->SetCursor(ui::mojom::CursorType::kPointer);
+
   aura::client::DragDropDelegate* delegate =
       aura::client::GetDragDropDelegate(target);
   if (delegate) {

ash/drag_drop/drag_drop_controller_unittest.cc

@@ -31,6 +31,7 @@
 #include "ui/base/clipboard/clipboard.h"
 #include "ui/base/clipboard/scoped_clipboard_writer.h"
 #include "ui/base/data_transfer_policy/data_transfer_endpoint.h"
+#include "ui/base/data_transfer_policy/data_transfer_policy_controller.h"
 #include "ui/base/dragdrop/drag_drop_types.h"
 #include "ui/base/dragdrop/mojom/drag_drop_types.mojom-shared.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
@@ -245,7 +246,8 @@ class EventTargetTestDelegate : public aura::client::DragDropDelegate {
     kNotInvoked,
     kDragEnteredInvoked,
     kDragUpdateInvoked,
-    kPerformDropInvoked
+    kPerformDropInvoked,
+    kDragExitInvoked
   };
 
   explicit EventTargetTestDelegate(aura::Window* window) : window_(window) {}
@@ -267,7 +269,11 @@ class EventTargetTestDelegate : public aura::client::DragDropDelegate {
         ui::DragDropTypes::DRAG_MOVE,
         ui::DataTransferEndpoint(ui::EndpointType::kDefault));
   }
-  void OnDragExited() override { ADD_FAILURE(); }
+  void OnDragExited() override {
+    EXPECT_TRUE(State::kDragEnteredInvoked == state_ ||
+                State::kDragUpdateInvoked == state_);
+    state_ = State::kDragExitInvoked;
+  }
   int OnPerformDrop(const ui::DropTargetEvent& event,
                     std::unique_ptr<ui::OSExchangeData> data) override {
     EXPECT_EQ(State::kDragUpdateInvoked, state_);
@@ -1474,4 +1480,88 @@ TEST_F(DragDropControllerTest, ToplevelWindowDragDelegate) {
   }
 }
 
+namespace {
+
+class MockDataTransferPolicyController
+    : public ui::DataTransferPolicyController {
+ public:
+  MOCK_METHOD2(IsClipboardReadAllowed,
+               bool(const ui::DataTransferEndpoint* const data_src,
+                    const ui::DataTransferEndpoint* const data_dst));
+  MOCK_METHOD2(IsDragDropAllowed,
+               bool(const ui::DataTransferEndpoint* const data_src,
+                    const ui::DataTransferEndpoint* const data_dst));
+};
+
+}  // namespace
+
+TEST_F(DragDropControllerTest, DlpAllowDragDrop) {
+  std::unique_ptr<aura::Window> window(CreateTestWindowInShellWithDelegate(
+      aura::test::TestWindowDelegate::CreateSelfDestroyingDelegate(), -1,
+      gfx::Rect(0, 0, 100, 100)));
+  EventTargetTestDelegate delegate(window.get());
+  aura::client::SetDragDropDelegate(window.get(), &delegate);
+
+  MockDataTransferPolicyController dlp_contoller;
+
+  // Posted task will be run when the inner loop runs in StartDragAndDrop.
+  ui::test::EventGenerator generator(window->GetRootWindow(), window.get());
+  generator.PressLeftButton();
+
+  auto data(std::make_unique<ui::OSExchangeData>());
+  data->SetString(base::UTF8ToUTF16("I am being dragged"));
+
+  EXPECT_CALL(dlp_contoller, IsDragDropAllowed)
+      .Times(2)
+      .WillRepeatedly(::testing::Return(true));
+
+  drag_drop_controller_->StartDragAndDrop(
+      std::move(data), window->GetRootWindow(), window.get(), gfx::Point(5, 5),
+      ui::DragDropTypes::DRAG_MOVE, ui::mojom::DragEventSource::kMouse);
+
+  // For drag enter
+  generator.MoveMouseBy(0, 1);
+  // For drag update
+  generator.MoveMouseBy(0, 1);
+  // For perform drop
+  generator.ReleaseLeftButton();
+
+  EXPECT_EQ(EventTargetTestDelegate::State::kPerformDropInvoked,
+            delegate.state());
+}
+
+TEST_F(DragDropControllerTest, DlpDisallowDragDrop) {
+  std::unique_ptr<aura::Window> window(CreateTestWindowInShellWithDelegate(
+      aura::test::TestWindowDelegate::CreateSelfDestroyingDelegate(), -1,
+      gfx::Rect(0, 0, 100, 100)));
+  EventTargetTestDelegate delegate(window.get());
+  aura::client::SetDragDropDelegate(window.get(), &delegate);
+
+  MockDataTransferPolicyController dlp_contoller;
+
+  // Posted task will be run when the inner loop runs in StartDragAndDrop.
+  ui::test::EventGenerator generator(window->GetRootWindow(), window.get());
+  generator.PressLeftButton();
+
+  auto data(std::make_unique<ui::OSExchangeData>());
+  data->SetString(base::UTF8ToUTF16("I am being dragged"));
+
+  EXPECT_CALL(dlp_contoller, IsDragDropAllowed)
+      .Times(2)
+      .WillRepeatedly(::testing::Return(false));
+
+  drag_drop_controller_->StartDragAndDrop(
+      std::move(data), window->GetRootWindow(), window.get(), gfx::Point(5, 5),
+      ui::DragDropTypes::DRAG_MOVE, ui::mojom::DragEventSource::kMouse);
+
+  // For drag enter
+  generator.MoveMouseBy(0, 1);
+  // For drag update
+  generator.MoveMouseBy(0, 1);
+  // For perform drop
+  generator.ReleaseLeftButton();
+
+  EXPECT_EQ(EventTargetTestDelegate::State::kDragExitInvoked, delegate.state());
+}
+
 }  // namespace ash

ui/base/data_transfer_policy/data_transfer_endpoint.h

@@ -63,6 +63,9 @@ class COMPONENT_EXPORT(UI_BASE_DATA_TRANSFER_POLICY) DataTransferEndpoint {
 
   EndpointType type() const { return type_; }
 
+  void set_notify_if_restricted(bool notify_if_restricted) {
+    notify_if_restricted_ = notify_if_restricted;
+  }
   bool notify_if_restricted() const { return notify_if_restricted_; }
 
  private: