commit 062a867e94dbf811ccca02e7a6a0f0e36465694a
author Vishnu Nair <vishnun@google.com> Fri Sep 03 16:07:44 2021 -0700
committer Vishnu Nair <vishnun@google.com> Wed Sep 15 18:22:56 2021 +0000
tree 356f0f9348df4127e2f3f01f10daa4fc4ff9662a
parent 880ca6d5e8d2d73bde500910c437c5020154e93f

InputFlinger: Add DROP_INPUT and DROP_INPUT_IF_OBSCURED feature flags

If a window has the feature DROP_INPUT set, then all touch and
key events directed to the window will be dropped. For touch events,
the events will not go to the window behind it.

If a window has the feature DROP_INPUT_IF_OBSCURED set, then all
touch and key events directed to the window will be dropped if
the window is considered partially or fully obscured.

These flags are used to enable features that allow for a less trusted
interaction model between apps. See the bug for more details.

Test: atest libgui_test InputDispatcherDropInputFeatureTest
Bug:197364677

Change-Id: I71d7cf5064c8ce4626cff09b92e15ca38b39cbbe

services/inputflinger/dispatcher/InputDispatcher.cpp

diff --git a/services/inputflinger/dispatcher/InputDispatcher.cpp b/services/inputflinger/dispatcher/InputDispatcher.cpp
index 058e099..0d0d1c4 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.cpp
+++ b/services/inputflinger/dispatcher/InputDispatcher.cpp
@@ -1868,6 +1868,11 @@
         return InputEventInjectionResult::FAILED;
     }
 
+    // Drop key events if requested by input feature
+    if (focusedWindowHandle != nullptr && shouldDropInput(entry, focusedWindowHandle)) {
+        return InputEventInjectionResult::FAILED;
+    }
+
     // Compatibility behavior: raise ANR if there is a focused application, but no focused window.
     // Only start counting when we have a focused event to dispatch. The ANR is canceled if we
     // start interacting with another application via touch (app switch). This code can be removed
@@ -2113,6 +2118,11 @@
             }
         }
 
+        // Drop touch events if requested by input feature
+        if (newTouchedWindowHandle != nullptr && shouldDropInput(entry, newTouchedWindowHandle)) {
+            newTouchedWindowHandle = nullptr;
+        }
+
         // Also don't send the new touch event to unresponsive gesture monitors
         newGestureMonitors = selectResponsiveMonitorsLocked(newGestureMonitors);
 
@@ -2178,6 +2188,13 @@
             sp<WindowInfoHandle> oldTouchedWindowHandle =
                     tempTouchState.getFirstForegroundWindowHandle();
             newTouchedWindowHandle = findTouchedWindowAtLocked(displayId, x, y, &tempTouchState);
+
+            // Drop touch events if requested by input feature
+            if (newTouchedWindowHandle != nullptr &&
+                shouldDropInput(entry, newTouchedWindowHandle)) {
+                newTouchedWindowHandle = nullptr;
+            }
+
             if (oldTouchedWindowHandle != newTouchedWindowHandle &&
                 oldTouchedWindowHandle != nullptr && newTouchedWindowHandle != nullptr) {
                 if (DEBUG_FOCUS) {
@@ -6180,4 +6197,19 @@
     setInputWindows(handlesPerDisplay);
 }
 
+bool InputDispatcher::shouldDropInput(
+        const EventEntry& entry, const sp<android::gui::WindowInfoHandle>& windowHandle) const {
+    if (windowHandle->getInfo()->inputFeatures.test(WindowInfo::Feature::DROP_INPUT) ||
+        (windowHandle->getInfo()->inputFeatures.test(WindowInfo::Feature::DROP_INPUT_IF_OBSCURED) &&
+         isWindowObscuredLocked(windowHandle))) {
+        ALOGW("Dropping %s event targeting %s as requested by input feature %s on display "
+              "%" PRId32 ".",
+              ftl::enum_string(entry.type).c_str(), windowHandle->getName().c_str(),
+              windowHandle->getInfo()->inputFeatures.string().c_str(),
+              windowHandle->getInfo()->displayId);
+        return true;
+    }
+    return false;
+}
+
 } // namespace android::inputdispatcher