commit cdcd8f2b25a4bf32bb7506fc98ba541d274c9a31
author Michael Wright <michaelwr@google.com> Tue Mar 22 16:52:13 2016 -0700
committer Michael Wright <michaelwr@google.com> Thu Mar 31 15:50:05 2016 -0700
tree 97c48382953203975b7c2b0cc8f798e6efbdac8d
parent e98a9a910692cf7dee3bac2b58cf5f08c59db38f

Add new MotionEvent flag for partially obscured windows.

Due to more complex window layouts resulting in lots of overlapping
windows, the policy around FLAG_WINDOW_IS_OBSCURED has changed to
only be set when the point at which the window was touched is
obscured. Unfortunately, this doesn't prevent tapjacking attacks that
overlay the dialog's text, making a potentially dangerous operation
seem innocuous. To avoid this on particularly sensitive dialogs,
introduce a new flag that really does tell you when your window is
being even partially overlapped.

We aren't exposing this as API since we plan on making the original
flag more robust. This is really a workaround for system dialogs
since we generally know their layout and screen position, and that
they're unlikely to be overlapped by other applications.

Bug: 26677796
Change-Id: I9e336afe90f262ba22015876769a9c510048fd47

services/inputflinger/InputDispatcher.cpp

diff --git a/services/inputflinger/InputDispatcher.cpp b/services/inputflinger/InputDispatcher.cpp
index 0fba1bf..c9e876f 100644
--- a/services/inputflinger/InputDispatcher.cpp
+++ b/services/inputflinger/InputDispatcher.cpp
@@ -1225,6 +1225,8 @@
                     int32_t outsideTargetFlags = InputTarget::FLAG_DISPATCH_AS_OUTSIDE;
                     if (isWindowObscuredAtPointLocked(windowHandle, x, y)) {
                         outsideTargetFlags |= InputTarget::FLAG_WINDOW_IS_OBSCURED;
+                    } else if (isWindowObscuredLocked(windowHandle)) {
+                        outsideTargetFlags |= InputTarget::FLAG_WINDOW_IS_PARTIALLY_OBSCURED;
                     }
 
                     mTempTouchState.addOrUpdateWindow(
@@ -1262,6 +1264,8 @@
         }
         if (isWindowObscuredAtPointLocked(newTouchedWindowHandle, x, y)) {
             targetFlags |= InputTarget::FLAG_WINDOW_IS_OBSCURED;
+        } else if (isWindowObscuredLocked(newTouchedWindowHandle)) {
+            targetFlags |= InputTarget::FLAG_WINDOW_IS_PARTIALLY_OBSCURED;
         }
 
         // Update hover state.
@@ -1437,6 +1441,7 @@
                                 == InputWindowInfo::TYPE_WALLPAPER) {
                     mTempTouchState.addOrUpdateWindow(windowHandle,
                             InputTarget::FLAG_WINDOW_IS_OBSCURED
+                                    | InputTarget::FLAG_WINDOW_IS_PARTIALLY_OBSCURED
                                     | InputTarget::FLAG_DISPATCH_AS_IS,
                             BitSet32(0));
                 }
@@ -1631,6 +1636,27 @@
     return false;
 }
 
+
+bool InputDispatcher::isWindowObscuredLocked(const sp<InputWindowHandle>& windowHandle) const {
+    int32_t displayId = windowHandle->getInfo()->displayId;
+    const InputWindowInfo* windowInfo = windowHandle->getInfo();
+    size_t numWindows = mWindowHandles.size();
+    for (size_t i = 0; i < numWindows; i++) {
+        sp<InputWindowHandle> otherHandle = mWindowHandles.itemAt(i);
+        if (otherHandle == windowHandle) {
+            break;
+        }
+
+        const InputWindowInfo* otherInfo = otherHandle->getInfo();
+        if (otherInfo->displayId == displayId
+                && otherInfo->visible && !otherInfo->isTrustedOverlay()
+                && otherInfo->overlaps(windowInfo)) {
+            return true;
+        }
+    }
+    return false;
+}
+
 String8 InputDispatcher::checkWindowReadyForMoreInputLocked(nsecs_t currentTime,
         const sp<InputWindowHandle>& windowHandle, const EventEntry* eventEntry,
         const char* targetType) {
@@ -1905,6 +1931,9 @@
         if (dispatchEntry->targetFlags & InputTarget::FLAG_WINDOW_IS_OBSCURED) {
             dispatchEntry->resolvedFlags |= AMOTION_EVENT_FLAG_WINDOW_IS_OBSCURED;
         }
+        if (dispatchEntry->targetFlags & InputTarget::FLAG_WINDOW_IS_PARTIALLY_OBSCURED) {
+            dispatchEntry->resolvedFlags |= AMOTION_EVENT_FLAG_WINDOW_IS_PARTIALLY_OBSCURED;
+        }
 
         if (!connection->inputState.trackMotion(motionEntry,
                 dispatchEntry->resolvedAction, dispatchEntry->resolvedFlags)) {