From 6ac8376cd79ff485dd5531fca3dff2b093c5ea15 Mon Sep 17 00:00:00 2001
From: Vishnu Nair <vishnun@google.com>
Date: Thu, 27 Jan 2022 23:29:32 +0000
Subject: [PATCH] Drop input for toast and child surfaces

Toasts that do not have the trustedOverlay flag should not receive input.
These windows should not have any children, so force this hierarchy of
windows to drop all input by setting a flag on the toast window state
which will apply the DROP_INPUT flag on all windows with an input
channel. This is to prevent malicious apps from parenting surfaces with
input channels to the toast window.

Test: show toast and check if input feature flag DROP_INPUT id set via dumpsys
Bug: b/197296414

Merged-In: I316b76b685ca5030fd8aa91283555efcce4d6994
Change-Id: I316b76b685ca5030fd8aa91283555efcce4d6994
---
 .../java/com/android/server/wm/DisplayPolicy.java | 15 +++++++++++++++
 .../android/server/wm/WindowManagerService.java   |  1 +
 2 files changed, 16 insertions(+)

diff --git a/services/core/java/com/android/server/wm/DisplayPolicy.java b/services/core/java/com/android/server/wm/DisplayPolicy.java
index 73d31bf7e0c80..1eb7281d37ed3 100644
--- a/services/core/java/com/android/server/wm/DisplayPolicy.java
+++ b/services/core/java/com/android/server/wm/DisplayPolicy.java
@@ -124,6 +124,7 @@ import android.graphics.Insets;
 import android.graphics.PixelFormat;
 import android.graphics.Rect;
 import android.graphics.Region;
+import android.gui.DropInputMode;
 import android.hardware.power.Boost;
 import android.os.Handler;
 import android.os.IBinder;
@@ -927,6 +928,20 @@ public class DisplayPolicy {
         }
     }
 
+    /**
+     * Add additional policy if needed to ensure the window or its children should not receive any
+     * input.
+     */
+    public void setDropInputModePolicy(WindowState win, LayoutParams attrs) {
+        if (attrs.type == TYPE_TOAST
+                && (attrs.privateFlags & PRIVATE_FLAG_TRUSTED_OVERLAY) == 0) {
+            // Toasts should not receive input. These windows should not have any children, so
+            // force this hierarchy of windows to drop all input.
+            mService.mTransactionFactory.get()
+                    .setDropInputMode(win.getSurfaceControl(), DropInputMode.ALL).apply();
+        }
+    }
+
     /**
      * Check if a window can be added to the system.
      *
diff --git a/services/core/java/com/android/server/wm/WindowManagerService.java b/services/core/java/com/android/server/wm/WindowManagerService.java
index 4281568b44d99..fac953910e927 100644
--- a/services/core/java/com/android/server/wm/WindowManagerService.java
+++ b/services/core/java/com/android/server/wm/WindowManagerService.java
@@ -1780,6 +1780,7 @@ public class WindowManagerService extends IWindowManager.Stub
 
             win.mToken.addWindow(win);
             displayPolicy.addWindowLw(win, attrs);
+            displayPolicy.setDropInputModePolicy(win, win.mAttrs);
             if (type == TYPE_INPUT_METHOD) {
                 displayContent.setInputMethodWindowLocked(win);
                 imMayMove = false;