From 81526702f5c4d08e28b53f8a414765724c3b2bcb Mon Sep 17 00:00:00 2001
From: Jacob Hobbie <jacobhobbie@google.com>
Date: Wed, 10 Nov 2021 22:08:04 +0000
Subject: [PATCH] Revert "Revert "Adding enforcement for receiver exported
 flags.""

This reverts commit ef1600614968711c8afc2810ad47f5c5a2ca57c9.

Reason for revert: The original CL that was reverted didn't create the bug

Change-Id: I5c9f9dce89035c19ac6af8c7e9df893845ed45ec
---
 .../server/am/ActivityManagerService.java     | 51 ++++++++++++++-----
 .../com/android/server/am/BroadcastQueue.java |  2 +-
 2 files changed, 38 insertions(+), 15 deletions(-)

diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index f6c110655e515..f36ee7afb1277 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -441,6 +441,14 @@ public class ActivityManagerService extends IActivityManager.Stub
     private static final String SYSTEM_PROPERTY_DEVICE_PROVISIONED =
             "persist.sys.device_provisioned";
 
+    /**
+     * Enabling this flag enforces the requirement for context registered receivers to use one of
+     * {@link Context#RECEIVER_EXPORTED} or {@link Context#RECEIVER_NOT_EXPORTED} for unprotected
+     * broadcasts
+     */
+    private static final boolean ENFORCE_DYNAMIC_RECEIVER_EXPLICIT_EXPORT =
+            SystemProperties.getBoolean("fw.enforce_dynamic_receiver_explicit_export", false);
+
     static final String TAG = TAG_WITH_CLASS_NAME ? "ActivityManagerService" : TAG_AM;
     static final String TAG_BACKUP = TAG + POSTFIX_BACKUP;
     private static final String TAG_BROADCAST = TAG + POSTFIX_BROADCAST;
@@ -12589,28 +12597,43 @@ public class ActivityManagerService extends IActivityManager.Stub
             // an error so the consumer can know to explicitly set the value for their flag.
             // If the caller is registering for a sticky broadcast with a null receiver, we won't
             // require a flag
-            if (!onlyProtectedBroadcasts && receiver != null && (
-                    CompatChanges.isChangeEnabled(
-                            DYNAMIC_RECEIVER_EXPLICIT_EXPORT_REQUIRED, callingUid)
-                            && (flags & (Context.RECEIVER_EXPORTED | Context.RECEIVER_NOT_EXPORTED))
-                            == 0)) {
-                Slog.e(TAG,
-                        callerPackage + ": Targeting T+ (version " + Build.VERSION_CODES.TIRAMISU
-                                + " and above) requires that one of RECEIVER_EXPORTED or "
-                                + "RECEIVER_NOT_EXPORTED be specified when registering a receiver");
-            } else if (((flags & Context.RECEIVER_EXPORTED) != 0) && (
+            final boolean explicitExportStateDefined =
+                    (flags & (Context.RECEIVER_EXPORTED | Context.RECEIVER_NOT_EXPORTED)) != 0;
+            if (((flags & Context.RECEIVER_EXPORTED) != 0) && (
                     (flags & Context.RECEIVER_NOT_EXPORTED) != 0)) {
                 throw new IllegalArgumentException(
                         "Receiver can't specify both RECEIVER_EXPORTED and RECEIVER_NOT_EXPORTED"
                                 + "flag");
             }
+            if (CompatChanges.isChangeEnabled(DYNAMIC_RECEIVER_EXPLICIT_EXPORT_REQUIRED,
+                    callingUid)
+                    && !explicitExportStateDefined) {
+                if (ENFORCE_DYNAMIC_RECEIVER_EXPLICIT_EXPORT) {
+                    throw new SecurityException(
+                            callerPackage + ": Targeting T+ (version "
+                                    + Build.VERSION_CODES.TIRAMISU
+                                    + " and above) requires that one of RECEIVER_EXPORTED or "
+                                    + "RECEIVER_NOT_EXPORTED be specified when registering a "
+                                    + "receiver");
+                } else {
+                    Slog.wtf(TAG,
+                            callerPackage + ": Targeting T+ (version "
+                                    + Build.VERSION_CODES.TIRAMISU
+                                    + " and above) requires that one of RECEIVER_EXPORTED or "
+                                    + "RECEIVER_NOT_EXPORTED be specified when registering a "
+                                    + "receiver");
+                    // Assume default behavior-- flag check is not enforced
+                    flags |= Context.RECEIVER_EXPORTED;
+                }
+            } else if (!CompatChanges.isChangeEnabled(DYNAMIC_RECEIVER_EXPLICIT_EXPORT_REQUIRED,
+                    callingUid)) {
+                // Change is not enabled, thus not targeting T+. Assume exported.
+                flags |= Context.RECEIVER_EXPORTED;
+            }
         }
 
         // Dynamic receivers are exported by default for versions prior to T
-        final boolean exported =
-                ((flags & Context.RECEIVER_EXPORTED) != 0
-                        || (!CompatChanges.isChangeEnabled(
-                        DYNAMIC_RECEIVER_EXPLICIT_EXPORT_REQUIRED, callingUid)));
+        final boolean exported = (flags & Context.RECEIVER_EXPORTED) != 0;
 
         ArrayList<Intent> allSticky = null;
         if (stickyIntents != null) {
diff --git a/services/core/java/com/android/server/am/BroadcastQueue.java b/services/core/java/com/android/server/am/BroadcastQueue.java
index 8638c7da4da22..fd6f0994ecfb5 100644
--- a/services/core/java/com/android/server/am/BroadcastQueue.java
+++ b/services/core/java/com/android/server/am/BroadcastQueue.java
@@ -792,7 +792,7 @@ public final class BroadcastQueue {
                     + " due to receiver " + filter.receiverList.app
                     + " (uid " + filter.receiverList.uid + ")"
                     + " not specifying RECEIVER_EXPORTED");
-            // skip = true;
+            skip = true;
         }
 
         if (skip) {