Protect invalid entitlement app configuration

There is a protection in Settings that Settings would gray out if
tethering requires entitlement check but the entitlement app is
invalid. Tethering resource is moved from framework to tethering
module, so Settings can not fetch entitlement app name anymore.

In this change, tethering module would check whether entitltement app
package name is exsited if entitlement check is needed. Tethering would
be not supported (Settings tethering option would be hidded) if
entitlement app is not installed.

After moving the protection into tethering module,
TetherUtil#isProvisioningNeeded is no longer needed. Because The
only use case is Settings wants to gray out tethering setting
when entitltement check is needed but entitlement app is invalid.

Bug: 146918263
Test: atest TetheringCoverageTests
Change-Id: I9a5ff5dbc1db3f3be7fcd7146862a16b373507e6
diff --git a/packages/SettingsLib/src/com/android/settingslib/TetherUtil.java b/packages/SettingsLib/src/com/android/settingslib/TetherUtil.java
index c3993e9..dc9384a 100644
--- a/packages/SettingsLib/src/com/android/settingslib/TetherUtil.java
+++ b/packages/SettingsLib/src/com/android/settingslib/TetherUtil.java
@@ -19,42 +19,9 @@
 
 import android.content.Context;
 import android.net.ConnectivityManager;
-import android.os.SystemProperties;
 import android.os.UserHandle;
-import android.telephony.CarrierConfigManager;
-
-import androidx.annotation.VisibleForTesting;
 
 public class TetherUtil {
-
-    @VisibleForTesting
-    static boolean isEntitlementCheckRequired(Context context) {
-        final CarrierConfigManager configManager = (CarrierConfigManager) context
-             .getSystemService(Context.CARRIER_CONFIG_SERVICE);
-        if (configManager == null || configManager.getConfig() == null) {
-            // return service default
-            return true;
-        }
-        return configManager.getConfig().getBoolean(CarrierConfigManager
-             .KEY_REQUIRE_ENTITLEMENT_CHECKS_BOOL);
-    }
-
-    public static boolean isProvisioningNeeded(Context context) {
-        // Keep in sync with other usage of config_mobile_hotspot_provision_app.
-        // ConnectivityManager#enforceTetherChangePermission
-        String[] provisionApp = context.getResources().getStringArray(
-                com.android.internal.R.array.config_mobile_hotspot_provision_app);
-        if (SystemProperties.getBoolean("net.tethering.noprovisioning", false)
-                || provisionApp == null) {
-            return false;
-        }
-        // Check carrier config for entitlement checks
-        if (isEntitlementCheckRequired(context) == false) {
-            return false;
-        }
-        return (provisionApp.length == 2);
-    }
-
     public static boolean isTetherAvailable(Context context) {
         final ConnectivityManager cm = context.getSystemService(ConnectivityManager.class);
         final boolean tetherConfigDisallowed = RestrictedLockUtilsInternal
diff --git a/packages/SettingsLib/tests/robotests/src/com/android/settingslib/TetherUtilTest.java b/packages/SettingsLib/tests/robotests/src/com/android/settingslib/TetherUtilTest.java
index 0ca7791..df08809 100644
--- a/packages/SettingsLib/tests/robotests/src/com/android/settingslib/TetherUtilTest.java
+++ b/packages/SettingsLib/tests/robotests/src/com/android/settingslib/TetherUtilTest.java
@@ -60,13 +60,6 @@
     }
 
     @Test
-    public void isEntitlementCheckRequired_noConfigManager_returnTrue() {
-        doReturn(null).when(mContext).getSystemService(Context.CARRIER_CONFIG_SERVICE);
-
-        assertThat(TetherUtil.isEntitlementCheckRequired(mContext)).isTrue();
-    }
-
-    @Test
     public void isTetherAvailable_supported_configDisallowed_hasUserRestriction_returnTrue() {
         setupIsTetherAvailable(true, true, true);
 
diff --git a/packages/Tethering/src/com/android/networkstack/tethering/Tethering.java b/packages/Tethering/src/com/android/networkstack/tethering/Tethering.java
index df67458..2f01186 100644
--- a/packages/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/packages/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -18,6 +18,7 @@
 
 import static android.Manifest.permission.NETWORK_SETTINGS;
 import static android.Manifest.permission.NETWORK_STACK;
+import static android.content.pm.PackageManager.GET_ACTIVITIES;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.hardware.usb.UsbManager.USB_CONFIGURED;
 import static android.hardware.usb.UsbManager.USB_CONNECTED;
@@ -70,6 +71,7 @@
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
+import android.content.pm.PackageManager;
 import android.hardware.usb.UsbManager;
 import android.net.ConnectivityManager;
 import android.net.EthernetManager;
@@ -109,7 +111,6 @@
 import android.os.RemoteException;
 import android.os.ResultReceiver;
 import android.os.ServiceSpecificException;
-import android.os.SystemProperties;
 import android.os.UserHandle;
 import android.os.UserManager;
 import android.provider.Settings;
@@ -782,11 +783,30 @@
         }
     }
 
+    private boolean isProvisioningNeededButUnavailable() {
+        return isTetherProvisioningRequired() && !doesEntitlementPackageExist();
+    }
+
     boolean isTetherProvisioningRequired() {
         final TetheringConfiguration cfg = mConfig;
         return mEntitlementMgr.isTetherProvisioningRequired(cfg);
     }
 
+    private boolean doesEntitlementPackageExist() {
+        // provisioningApp must contain package and class name.
+        if (mConfig.provisioningApp.length != 2) {
+            return false;
+        }
+
+        final PackageManager pm = mContext.getPackageManager();
+        try {
+            pm.getPackageInfo(mConfig.provisioningApp[0], GET_ACTIVITIES);
+        } catch (PackageManager.NameNotFoundException e) {
+            return false;
+        }
+        return true;
+    }
+
     // TODO: Figure out how to update for local hotspot mode interfaces.
     private void sendTetherStateChangedBroadcast() {
         if (!isTetheringSupported()) return;
@@ -2145,14 +2165,14 @@
     // gservices could set the secure setting to 1 though to enable it on a build where it
     // had previously been turned off.
     boolean isTetheringSupported() {
-        final int defaultVal =
-                SystemProperties.get("ro.tether.denied").equals("true") ? 0 : 1;
+        final int defaultVal = mDeps.isTetheringDenied() ? 0 : 1;
         final boolean tetherSupported = Settings.Global.getInt(mContext.getContentResolver(),
                 Settings.Global.TETHER_SUPPORTED, defaultVal) != 0;
         final boolean tetherEnabledInSettings = tetherSupported
                 && !mUserManager.hasUserRestriction(UserManager.DISALLOW_CONFIG_TETHERING);
 
-        return tetherEnabledInSettings && hasTetherableConfiguration();
+        return tetherEnabledInSettings && hasTetherableConfiguration()
+                && !isProvisioningNeededButUnavailable();
     }
 
     void dump(@NonNull FileDescriptor fd, @NonNull PrintWriter writer, @Nullable String[] args) {
diff --git a/packages/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java b/packages/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
index d637c86..31f747d 100644
--- a/packages/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
+++ b/packages/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
@@ -26,6 +26,8 @@
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.Looper;
+import android.os.SystemProperties;
+import android.text.TextUtils;
 
 import androidx.annotation.NonNull;
 
@@ -150,4 +152,11 @@
      * Get a reference to BluetoothAdapter to be used by tethering.
      */
     public abstract BluetoothAdapter getBluetoothAdapter();
+
+    /**
+     * Get SystemProperties which indicate whether tethering is denied.
+     */
+    public boolean isTetheringDenied() {
+        return TextUtils.equals(SystemProperties.get("ro.tether.denied"), "true");
+    }
 }
diff --git a/packages/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java b/packages/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
index 8146a58d..f53c42b 100644
--- a/packages/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
+++ b/packages/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
@@ -16,6 +16,7 @@
 
 package com.android.networkstack.tethering;
 
+import static android.content.pm.PackageManager.GET_ACTIVITIES;
 import static android.hardware.usb.UsbManager.USB_CONFIGURED;
 import static android.hardware.usb.UsbManager.USB_CONNECTED;
 import static android.hardware.usb.UsbManager.USB_FUNCTION_NCM;
@@ -81,6 +82,7 @@
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
 import android.content.res.Resources;
 import android.hardware.usb.UsbManager;
 import android.net.ConnectivityManager;
@@ -204,6 +206,7 @@
     @Mock private EthernetManager mEm;
     @Mock private TetheringNotificationUpdater mNotificationUpdater;
     @Mock private BpfCoordinator mBpfCoordinator;
+    @Mock private PackageManager mPackageManager;
 
     private final MockIpServerDependencies mIpServerDependencies =
             spy(new MockIpServerDependencies());
@@ -264,6 +267,11 @@
         }
 
         @Override
+        public PackageManager getPackageManager() {
+            return mPackageManager;
+        }
+
+        @Override
         public String getSystemServiceName(Class<?> serviceClass) {
             if (TelephonyManager.class.equals(serviceClass)) return Context.TELEPHONY_SERVICE;
             return super.getSystemServiceName(serviceClass);
@@ -425,6 +433,11 @@
         public TetheringNotificationUpdater getNotificationUpdater(Context ctx, Looper looper) {
             return mNotificationUpdater;
         }
+
+        @Override
+        public boolean isTetheringDenied() {
+            return false;
+        }
     }
 
     private static UpstreamNetworkState buildMobileUpstreamState(boolean withIPv4,
@@ -1951,6 +1964,23 @@
         assertEquals(TETHER_ERROR_IFACE_CFG_ERROR, mTethering.getLastTetherError(TEST_ETH_IFNAME));
     }
 
+    @Test
+    public void testProvisioningNeededButUnavailable() throws Exception {
+        assertTrue(mTethering.isTetheringSupported());
+        verify(mPackageManager, never()).getPackageInfo(PROVISIONING_APP_NAME[0], GET_ACTIVITIES);
+
+        setupForRequiredProvisioning();
+        assertTrue(mTethering.isTetheringSupported());
+        verify(mPackageManager).getPackageInfo(PROVISIONING_APP_NAME[0], GET_ACTIVITIES);
+        reset(mPackageManager);
+
+        doThrow(PackageManager.NameNotFoundException.class).when(mPackageManager).getPackageInfo(
+                PROVISIONING_APP_NAME[0], GET_ACTIVITIES);
+        setupForRequiredProvisioning();
+        assertFalse(mTethering.isTetheringSupported());
+        verify(mPackageManager).getPackageInfo(PROVISIONING_APP_NAME[0], GET_ACTIVITIES);
+    }
+
     // TODO: Test that a request for hotspot mode doesn't interfere with an
     // already operating tethering mode interface.
 }