Add mechanism for a task's windows to be trusted overlays (SF)

- Add a layer state to indicate that this layer and its children
  in the hierarchy are trusted. This can only be set by callers
  holding ACCESS_SURFACE_FLINGER, and will be used for the PIP
  task layer to indicate that activities in PIP are trusted (as
  they are controlled only by the user and SystemUI)

Bug: 191529039
Bug: 196389741
Test: TBD

Change-Id: Id92ccb087bd0d8dbaeeef3ba50b67fe015e53db8
Merged-In: Id92ccb087bd0d8dbaeeef3ba50b67fe015e53db8

1 files changed, 22 insertions, 0 deletions

diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 03903f6d07..ceea79f980 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -1142,6 +1142,23 @@ bool Layer::setRelativeLayer(const sp<IBinder>& relativeToHandle, int32_t relati
     return true;
 }
 
+bool Layer::setTrustedOverlay(bool isTrustedOverlay) {
+    if (mCurrentState.isTrustedOverlay == isTrustedOverlay) return false;
+    mCurrentState.isTrustedOverlay = isTrustedOverlay;
+    mCurrentState.modified = true;
+    mCurrentState.inputInfoChanged = true;
+    setTransactionFlags(eTransactionNeeded);
+    return true;
+}
+
+bool Layer::isTrustedOverlay() const {
+    if (getDrawingState().isTrustedOverlay) {
+        return true;
+    }
+    const auto& p = mDrawingParent.promote();
+    return (p != nullptr) && p->isTrustedOverlay();
+}
+
 bool Layer::setSize(uint32_t w, uint32_t h) {
     if (mCurrentState.requested_legacy.w == w && mCurrentState.requested_legacy.h == h)
         return false;
@@ -2245,6 +2262,7 @@ void Layer::writeToProtoDrawingState(LayerProto* layerInfo, uint32_t traceFlags,
         layerInfo->set_effective_scaling_mode(getEffectiveScalingMode());
 
         layerInfo->set_corner_radius(getRoundedCornerState().radius);
+        layerInfo->set_is_trusted_overlay(isTrustedOverlay());
         LayerProtoHelper::writeToProto(transform, layerInfo->mutable_transform());
         LayerProtoHelper::writePositionToProto(transform.tx(), transform.ty(),
                                                [&]() { return layerInfo->mutable_position(); });
@@ -2435,6 +2453,10 @@ InputWindowInfo Layer::fillInputInfo() {
         info.touchableRegion = info.touchableRegion.intersect(Rect{cropLayer->mScreenBounds});
     }
 
+    // Inherit the trusted state from the parent hierarchy, but don't clobber the trusted state
+    // if it was set by WM for a known system overlay
+    info.trustedOverlay = info.trustedOverlay || isTrustedOverlay();
+
     // If the layer is a clone, we need to crop the input region to cloned root to prevent
     // touches from going outside the cloned area.
     if (isClone()) {