VPN: move VpnDialogs away from system uid.

Bug: 6632536
Change-Id: Iece647c077caf5298ccfe7d7aba5f0911a4ed0d1

Author: Chia-chi Yeh

core/java/com/android/internal/net/VpnConfig.java

@@ -34,17 +34,19 @@ public class VpnConfig implements Parcelable {
 
     public static final String SERVICE_INTERFACE = "android.net.VpnService";
 
+    public static final String DIALOGS_PACKAGE = "com.android.vpndialogs";
+
     public static final String LEGACY_VPN = "[Legacy VPN]";
 
     public static Intent getIntentForConfirmation() {
         Intent intent = new Intent();
-        intent.setClassName("com.android.vpndialogs", "com.android.vpndialogs.ConfirmDialog");
+        intent.setClassName(DIALOGS_PACKAGE, DIALOGS_PACKAGE + ".ConfirmDialog");
         return intent;
     }
 
     public static PendingIntent getIntentForStatusPanel(Context context, VpnConfig config) {
         Intent intent = new Intent();
-        intent.setClassName("com.android.vpndialogs", "com.android.vpndialogs.ManageDialog");
+        intent.setClassName(DIALOGS_PACKAGE, DIALOGS_PACKAGE + ".ManageDialog");
         intent.putExtra("config", config);
         intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_NO_HISTORY |
                 Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);

packages/VpnDialogs/AndroidManifest.xml

@@ -1,6 +1,5 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-        package="com.android.vpndialogs"
-        android:sharedUserId="android.uid.system">
+        package="com.android.vpndialogs">
 
     <application android:label="VpnDialogs"
             android:allowBackup="false" >

services/java/com/android/server/connectivity/Vpn.java

@@ -106,16 +106,16 @@ public synchronized boolean prepare(String oldPackage, String newPackage) {
             return true;
         }
 
-        // Only system user can revoke a package.
-        if (Binder.getCallingUid() != Process.SYSTEM_UID) {
-            throw new SecurityException("Unauthorized Caller");
-        }
+        // Check if the caller is authorized.
+        enforceControlPermission();
 
         // Reset the interface and hide the notification.
         if (mInterface != null) {
             jniReset(mInterface);
+            long identity = Binder.clearCallingIdentity();
             mCallback.restore();
             hideNotification();
+            Binder.restoreCallingIdentity(identity);
             mInterface = null;
         }
 
@@ -291,6 +291,26 @@ public synchronized void interfaceRemoved(String interfaze) {
     public void limitReached(String limit, String interfaze) {
     }
 
+    private void enforceControlPermission() {
+        // System user is allowed to control VPN.
+        if (Binder.getCallingUid() == Process.SYSTEM_UID) {
+            return;
+        }
+
+        try {
+            // System dialogs are also allowed to control VPN.
+            PackageManager pm = mContext.getPackageManager();
+            ApplicationInfo app = pm.getApplicationInfo(VpnConfig.DIALOGS_PACKAGE, 0);
+            if (Binder.getCallingUid() == app.uid) {
+                return;
+            }
+        } catch (Exception e) {
+            // ignore
+        }
+
+        throw new SecurityException("Unauthorized Caller");
+    }
+
     private class Connection implements ServiceConnection {
         private IBinder mService;
 
@@ -368,10 +388,8 @@ public synchronized void startLegacyVpn(VpnConfig config, String[] racoon, Strin
      * Return the information of the current ongoing legacy VPN.
      */
     public synchronized LegacyVpnInfo getLegacyVpnInfo() {
-        // Only system user can call this method.
-        if (Binder.getCallingUid() != Process.SYSTEM_UID) {
-            throw new SecurityException("Unauthorized Caller");
-        }
+        // Check if the caller is authorized.
+        enforceControlPermission();
         return (mLegacyVpnRunner == null) ? null : mLegacyVpnRunner.getInfo();
     }