Clear calling identity to grant CDM permission when checking device config.

Bug: 286942347
Test: m services.companion
Change-Id: I88b399636123a4a394f2a280a19692c55a9d2441
Merged-In: I88b399636123a4a394f2a280a19692c55a9d2441

core/java/android/companion/CompanionDeviceManager.java

@@ -36,7 +36,6 @@ import android.app.NotificationManager;
 import android.app.PendingIntent;
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothDevice;
-import android.companion.utils.FeatureUtils;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
@@ -1227,11 +1226,6 @@ public final class CompanionDeviceManager {
     @Nullable
     public IntentSender buildPermissionTransferUserConsentIntent(int associationId)
             throws DeviceNotAssociatedException {
-        if (!FeatureUtils.isPermSyncEnabled()) {
-            throw new UnsupportedOperationException("Calling"
-                    + " buildPermissionTransferUserConsentIntent, but this API is disabled by the"
-                    + " system.");
-        }
         try {
             PendingIntent pendingIntent = mService.buildPermissionTransferUserConsentIntent(
                     mContext.getOpPackageName(),
@@ -1264,10 +1258,6 @@ public final class CompanionDeviceManager {
     @Deprecated
     @UserHandleAware
     public void startSystemDataTransfer(int associationId) throws DeviceNotAssociatedException {
-        if (!FeatureUtils.isPermSyncEnabled()) {
-            throw new UnsupportedOperationException("Calling startSystemDataTransfer, but this API"
-                    + " is disabled by the system.");
-        }
         try {
             mService.startSystemDataTransfer(mContext.getOpPackageName(), mContext.getUserId(),
                     associationId, null);
@@ -1300,10 +1290,6 @@ public final class CompanionDeviceManager {
             @NonNull Executor executor,
             @NonNull OutcomeReceiver<Void, CompanionException> result)
             throws DeviceNotAssociatedException {
-        if (!FeatureUtils.isPermSyncEnabled()) {
-            throw new UnsupportedOperationException("Calling startSystemDataTransfer, but this API"
-                    + " is disabled by the system.");
-        }
         try {
             mService.startSystemDataTransfer(mContext.getOpPackageName(), mContext.getUserId(),
                     associationId, new SystemDataTransferCallbackProxy(executor, result));

core/java/android/companion/utils/FeatureUtils.java

@@ -16,6 +16,7 @@
 
 package android.companion.utils;
 
+import android.os.Binder;
 import android.os.Build;
 import android.provider.DeviceConfig;
 
@@ -31,8 +32,19 @@ public final class FeatureUtils {
     private static final String PROPERTY_PERM_SYNC_ENABLED = "perm_sync_enabled";
 
     public static boolean isPermSyncEnabled() {
-        return Build.isDebuggable() || DeviceConfig.getBoolean(NAMESPACE_COMPANION,
-                PROPERTY_PERM_SYNC_ENABLED, false);
+        // Permissions sync is always enabled in debuggable mode.
+        if (Build.isDebuggable()) {
+            return true;
+        }
+
+        // Clear app identity to read the device config for feature flag.
+        final long identity = Binder.clearCallingIdentity();
+        try {
+            return DeviceConfig.getBoolean(NAMESPACE_COMPANION,
+                    PROPERTY_PERM_SYNC_ENABLED, false);
+        } finally {
+            Binder.restoreCallingIdentity(identity);
+        }
     }
 
     private FeatureUtils() {

services/companion/java/com/android/server/companion/CompanionDeviceManagerService.java

@@ -64,6 +64,7 @@ import android.companion.IOnAssociationsChangedListener;
 import android.companion.IOnMessageReceivedListener;
 import android.companion.IOnTransportsChangedListener;
 import android.companion.ISystemDataTransferCallback;
+import android.companion.utils.FeatureUtils;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.SharedPreferences;
@@ -746,6 +747,11 @@ public class CompanionDeviceManagerService extends SystemService {
         @Override
         public PendingIntent buildPermissionTransferUserConsentIntent(String packageName,
                 int userId, int associationId) {
+            if (!FeatureUtils.isPermSyncEnabled()) {
+                throw new UnsupportedOperationException("Calling"
+                        + " buildPermissionTransferUserConsentIntent, but this API is disabled by"
+                        + " the system.");
+            }
             return mSystemDataTransferProcessor.buildPermissionTransferUserConsentIntent(
                     packageName, userId, associationId);
         }
@@ -753,6 +759,10 @@ public class CompanionDeviceManagerService extends SystemService {
         @Override
         public void startSystemDataTransfer(String packageName, int userId, int associationId,
                 ISystemDataTransferCallback callback) {
+            if (!FeatureUtils.isPermSyncEnabled()) {
+                throw new UnsupportedOperationException("Calling startSystemDataTransfer, but this"
+                        + " API is disabled by the system.");
+            }
             mSystemDataTransferProcessor.startSystemDataTransfer(packageName, userId,
                     associationId, callback);
         }

services/companion/java/com/android/server/companion/transport/CompanionTransportManager.java

@@ -22,14 +22,10 @@ import static com.android.server.companion.transport.Transport.MESSAGE_REQUEST_P
 
 import android.annotation.NonNull;
 import android.annotation.SuppressLint;
-import android.app.ActivityManagerInternal;
 import android.companion.AssociationInfo;
 import android.companion.IOnMessageReceivedListener;
 import android.companion.IOnTransportsChangedListener;
 import android.content.Context;
-import android.content.pm.ApplicationInfo;
-import android.content.pm.PackageManager.NameNotFoundException;
-import android.os.Binder;
 import android.os.Build;
 import android.os.ParcelFileDescriptor;
 import android.os.RemoteCallbackList;
@@ -38,7 +34,6 @@ import android.util.Slog;
 import android.util.SparseArray;
 
 import com.android.internal.annotations.GuardedBy;
-import com.android.server.LocalServices;
 import com.android.server.companion.AssociationStore;
 
 import java.io.FileDescriptor;
@@ -143,32 +138,9 @@ public class CompanionTransportManager {
         }
     }
 
-    /**
-     * For the moment, we only offer transporting of system data to built-in
-     * companion apps; future work will improve the security model to support
-     * third-party companion apps.
-     */
-    private void enforceCallerCanTransportSystemData(String packageName, int userId) {
-        mContext.enforceCallingOrSelfPermission(DELIVER_COMPANION_MESSAGES, TAG);
-
-        try {
-            final ApplicationInfo info = mContext.getPackageManager().getApplicationInfoAsUser(
-                    packageName, 0, userId);
-            final int instrumentationUid = LocalServices.getService(ActivityManagerInternal.class)
-                    .getInstrumentationSourceUid(Binder.getCallingUid());
-            if (!Build.isDebuggable() && !info.isSystemApp()
-                    && instrumentationUid == android.os.Process.INVALID_UID) {
-                throw new SecurityException("Transporting of system data currently only available "
-                        + "to built-in companion apps or tests");
-            }
-        } catch (NameNotFoundException e) {
-            throw new IllegalArgumentException(e);
-        }
-    }
-
     public void attachSystemDataTransport(String packageName, int userId, int associationId,
             ParcelFileDescriptor fd) {
-        enforceCallerCanTransportSystemData(packageName, userId);
+        mContext.enforceCallingOrSelfPermission(DELIVER_COMPANION_MESSAGES, TAG);
         synchronized (mTransports) {
             if (mTransports.contains(associationId)) {
                 detachSystemDataTransport(packageName, userId, associationId);
@@ -182,7 +154,7 @@ public class CompanionTransportManager {
     }
 
     public void detachSystemDataTransport(String packageName, int userId, int associationId) {
-        enforceCallerCanTransportSystemData(packageName, userId);
+        mContext.enforceCallingOrSelfPermission(DELIVER_COMPANION_MESSAGES, TAG);
         synchronized (mTransports) {
             final Transport transport = mTransports.get(associationId);
             if (transport != null) {

services/companion/java/com/android/server/companion/transport/Transport.java

@@ -19,7 +19,6 @@ package com.android.server.companion.transport;
 import android.annotation.NonNull;
 import android.companion.IOnMessageReceivedListener;
 import android.content.Context;
-import android.content.pm.PackageManager;
 import android.os.Build;
 import android.os.ParcelFileDescriptor;
 import android.os.RemoteException;
@@ -188,12 +187,6 @@ public abstract class Transport {
                 break;
             }
             case MESSAGE_REQUEST_PERMISSION_RESTORE: {
-                if (!mContext.getPackageManager().hasSystemFeature(PackageManager.FEATURE_WATCH)
-                        && !Build.isDebuggable()) {
-                    Slog.w(TAG, "Restoring permissions only supported on watches");
-                    sendMessage(MESSAGE_RESPONSE_FAILURE, sequence, EmptyArray.BYTE);
-                    break;
-                }
                 try {
                     callback(message, data);
                     sendMessage(MESSAGE_RESPONSE_SUCCESS, sequence, EmptyArray.BYTE);