commit cbe9c105fcdeba79f1722616e8b576c1d45c93a6
author Vishnu Nair <vishnun@google.com> Tue Feb 08 02:53:27 2022 +0000
committer Vishnu Nair <vishnun@google.com> Wed Feb 16 18:59:01 2022 +0000
tree ddd4d3c41e454b0bdd07afe5ead58948a1c33fd9
parent 0f13fe552dcca56a7597a354a6b94587981c3d12

SurfaceFlinger: Implement drop input modes

ALL: If this mode is set on a layer, set the DROP_INPUT
feature flag on the layer and its children if it has a valid input
channel. This will ensure these layers will not be able to receive any
input.

Note: this backport does not include the OBSCURED option since its
not needed for the security fix.

Test: atest libgui_test InputDispatcherDropInputFeatureTest
Bug: 197296414

Merged-In: Ibce11ee7df5b5c8c226ebfab29574a99cd656f6d
Change-Id: Ibce11ee7df5b5c8c226ebfab29574a99cd656f6d

services/surfaceflinger/Layer.cpp

diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index bae242a..0691418 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -2378,6 +2378,36 @@
     return mRemovedFromCurrentState;
 }
 
+gui::DropInputMode Layer::getDropInputMode() const {
+    gui::DropInputMode mode = mDrawingState.dropInputMode;
+    if (mode == gui::DropInputMode::ALL) {
+        return mode;
+    }
+    sp<Layer> parent = mDrawingParent.promote();
+    if (parent) {
+        gui::DropInputMode parentMode = parent->getDropInputMode();
+        if (parentMode != gui::DropInputMode::NONE) {
+            return parentMode;
+        }
+    }
+    return mode;
+}
+
+void Layer::handleDropInputMode(InputWindowInfo& info) const {
+    if ((mDrawingState.inputInfo.inputFeatures & InputWindowInfo::INPUT_FEATURE_NO_INPUT_CHANNEL) ==
+        InputWindowInfo::INPUT_FEATURE_NO_INPUT_CHANNEL) {
+        return;
+    }
+
+    // Check if we need to drop input unconditionally
+    gui::DropInputMode dropInputMode = getDropInputMode();
+    if (dropInputMode == gui::DropInputMode::ALL) {
+        info.inputFeatures |= InputWindowInfo::INPUT_FEATURE_DROP_INPUT;
+        ALOGV("Dropping input for %s as requested by policy.", getDebugName());
+        return;
+    }
+}
+
 InputWindowInfo Layer::fillInputInfo() {
     if (!hasInputInfo()) {
         mDrawingState.inputInfo.name = getName();
@@ -2443,6 +2473,7 @@
     // InputDispatcher, and obviously if they aren't visible they can't occlude
     // anything.
     info.visible = hasInputInfo() ? canReceiveInput() : isVisible();
+    handleDropInputMode(info);
 
     auto cropLayer = mDrawingState.touchableRegionCrop.promote();
     if (info.replaceTouchableRegionWithCrop) {

services/surfaceflinger/Layer.h

diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 30f207f..6c5d114 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -1074,6 +1074,8 @@
 
     void updateTreeHasFrameRateVote();
     bool isTrustedOverlay() const;
+    gui::DropInputMode getDropInputMode() const;
+    void handleDropInputMode(InputWindowInfo& info) const;
 
     // Cached properties computed from drawing state
     // Effective transform taking into account parent transforms and any parent scaling.