Prevent disconnecting admin-configured VPN

First, if the VPN is configured by an admin, the preference is
disabled and tapping on it will results in a policy disclouser
dialog.
In addition restriction checks in the dialog also check if the
VPN is admin-configured.

Bug: 179975048
Test: Manual, setting VPN in profile and primary user and via DPM API.
Test: make RunSettingsRoboTests -j
Merged-In: Id59d2ac2782e83601bc3093d3a092faea36ff5d9
Change-Id: Id59d2ac2782e83601bc3093d3a092faea36ff5d9

src/com/android/settings/vpn2/AppDialogFragment.java

diff --git a/src/com/android/settings/vpn2/AppDialogFragment.java b/src/com/android/settings/vpn2/AppDialogFragment.java
index ea9e546..60c6596 100644
--- a/src/com/android/settings/vpn2/AppDialogFragment.java
+++ b/src/com/android/settings/vpn2/AppDialogFragment.java
@@ -17,6 +17,7 @@
 package com.android.settings.vpn2;
 
 import android.app.Dialog;
+import android.app.admin.DevicePolicyManager;
 import android.app.settings.SettingsEnums;
 import android.content.Context;
 import android.content.DialogInterface;
@@ -55,6 +56,7 @@
     private UserManager mUserManager;
     private final IConnectivityManager mService = IConnectivityManager.Stub.asInterface(
             ServiceManager.getService(Context.CONNECTIVITY_SERVICE));
+    private DevicePolicyManager mDevicePolicyManager;
 
     @Override
     public int getMetricsCategory() {
@@ -97,7 +99,11 @@
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        mPackageInfo = getArguments().getParcelable(ARG_PACKAGE);
         mUserManager = UserManager.get(getContext());
+        mDevicePolicyManager = getContext()
+                .createContextAsUser(UserHandle.of(getUserId()), /* flags= */ 0)
+                .getSystemService(DevicePolicyManager.class);
     }
 
     @Override
@@ -106,7 +112,6 @@
         final String label = args.getString(ARG_LABEL);
         boolean managing = args.getBoolean(ARG_MANAGING);
         boolean connected = args.getBoolean(ARG_CONNECTED);
-        mPackageInfo = args.getParcelable(ARG_PACKAGE);
 
         if (managing) {
             return new AppDialog(getActivity(), this, mPackageInfo, label);
@@ -178,7 +183,10 @@
 
     private boolean isUiRestricted() {
         final UserHandle userHandle = UserHandle.of(getUserId());
-        return mUserManager.hasUserRestriction(UserManager.DISALLOW_CONFIG_VPN, userHandle);
+        if (mUserManager.hasUserRestriction(UserManager.DISALLOW_CONFIG_VPN, userHandle)) {
+            return true;
+        }
+        return mPackageInfo.packageName.equals(mDevicePolicyManager.getAlwaysOnVpnPackage());
     }
 
     private int getUserId() {

src/com/android/settings/vpn2/AppPreference.java

diff --git a/src/com/android/settings/vpn2/AppPreference.java b/src/com/android/settings/vpn2/AppPreference.java
index 6b64250..8ee2f5f 100644
--- a/src/com/android/settings/vpn2/AppPreference.java
+++ b/src/com/android/settings/vpn2/AppPreference.java
@@ -16,6 +16,7 @@
 
 package com.android.settings.vpn2;
 
+import android.app.admin.DevicePolicyManager;
 import android.content.Context;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
@@ -26,6 +27,8 @@
 
 import com.android.internal.net.LegacyVpnInfo;
 import com.android.internal.net.VpnConfig;
+import com.android.settingslib.RestrictedLockUtils;
+import com.android.settingslib.RestrictedLockUtils.EnforcedAdmin;
 
 /**
  * {@link androidx.preference.Preference} containing information about a VPN
@@ -43,6 +46,7 @@
         super.setUserId(userId);
 
         mPackageName = packageName;
+        disableIfConfiguredByAdmin();
 
         // Fetch icon and VPN label
         String label = packageName;
@@ -74,6 +78,25 @@
         setIcon(icon);
     }
 
+    /**
+     * Disable this preference if VPN is set as always on by a profile or device owner.
+     * NB: it should be called after super.setUserId() otherwise admin information can be lost.
+     */
+    private void disableIfConfiguredByAdmin() {
+        if (isDisabledByAdmin()) {
+            // Already disabled due to user restriction.
+            return;
+        }
+        final DevicePolicyManager dpm = getContext()
+                .createContextAsUser(UserHandle.of(getUserId()), /* flags= */ 0)
+                .getSystemService(DevicePolicyManager.class);
+        if (mPackageName.equals(dpm.getAlwaysOnVpnPackage())) {
+            final EnforcedAdmin admin = RestrictedLockUtils.getProfileOrDeviceOwner(
+                    getContext(), UserHandle.of(mUserId));
+            setDisabledByAdmin(admin);
+        }
+    }
+
     public PackageInfo getPackageInfo() {
         try {
             PackageManager pm = getUserContext().getPackageManager();