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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.server.oemlock;
     18 
     19 import android.annotation.Nullable;
     20 import android.content.Context;
     21 import android.os.UserHandle;
     22 import android.os.UserManager;
     23 import android.service.persistentdata.PersistentDataBlockManager;
     24 import android.util.Slog;
     25 
     26 /**
     27  * Implementation of the OEM lock using the persistent data block to communicate with the
     28  * bootloader.
     29  *
     30  * The carrier flag is stored as a user restriction on the system user. The user flag is set in the
     31  * presistent data block but depends on the carrier flag.
     32  */
     33 class PersistentDataBlockLock extends OemLock {
     34     private static final String TAG = "OemLock";
     35 
     36     private Context mContext;
     37 
     38     PersistentDataBlockLock(Context context) {
     39         mContext = context;
     40     }
     41 
     42     @Override
     43     void setOemUnlockAllowedByCarrier(boolean allowed, @Nullable byte[] signature) {
     44         // Note: this implementation does not require a signature
     45         if (signature != null) {
     46             Slog.w(TAG, "Signature provided but is not being used");
     47         }
     48 
     49         // Continue using user restriction for backwards compatibility
     50         UserManager.get(mContext).setUserRestriction(
     51                 UserManager.DISALLOW_OEM_UNLOCK, !allowed, UserHandle.SYSTEM);
     52 
     53         if (!allowed) {
     54             disallowUnlockIfNotUnlocked();
     55         }
     56     }
     57 
     58     @Override
     59     boolean isOemUnlockAllowedByCarrier() {
     60         return !UserManager.get(mContext)
     61                 .hasUserRestriction(UserManager.DISALLOW_OEM_UNLOCK, UserHandle.SYSTEM);
     62     }
     63 
     64     @Override
     65     void setOemUnlockAllowedByDevice(boolean allowedByDevice) {
     66         // The method name is misleading as it really just means whether or not the device can be
     67         // unlocked but doesn't actually do any unlocking.
     68         final PersistentDataBlockManager pdbm = (PersistentDataBlockManager)
     69                 mContext.getSystemService(Context.PERSISTENT_DATA_BLOCK_SERVICE);
     70         pdbm.setOemUnlockEnabled(allowedByDevice);
     71     }
     72 
     73     @Override
     74     boolean isOemUnlockAllowedByDevice() {
     75         final PersistentDataBlockManager pdbm = (PersistentDataBlockManager)
     76             mContext.getSystemService(Context.PERSISTENT_DATA_BLOCK_SERVICE);
     77         return pdbm.getOemUnlockEnabled();
     78     }
     79 
     80     /**
     81      * Update state to prevent the bootloader from being able to unlock the device unless the device
     82      * has already been unlocked by the bootloader in which case it is too late as it would remain
     83      * unlocked.
     84      */
     85     private void disallowUnlockIfNotUnlocked() {
     86         final PersistentDataBlockManager pdbm = (PersistentDataBlockManager)
     87             mContext.getSystemService(Context.PERSISTENT_DATA_BLOCK_SERVICE);
     88         if (pdbm.getFlashLockState() != PersistentDataBlockManager.FLASH_LOCK_UNLOCKED) {
     89             pdbm.setOemUnlockEnabled(false);
     90         }
     91     }
     92 }
     93