services/core/java/com/android/server/LockSettingsService.java

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.server;

import android.app.ActivityManagerNative;
import android.app.KeyguardManager;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.admin.DevicePolicyManager;
import android.app.backup.BackupManager;
import android.app.trust.IStrongAuthTracker;
import android.app.trust.TrustManager;
import android.content.BroadcastReceiver;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.content.pm.UserInfo;
import android.content.res.Resources;

import static android.Manifest.permission.ACCESS_KEYGUARD_SECURE_STORAGE;
import static android.content.Context.KEYGUARD_SERVICE;
import static android.content.Context.USER_SERVICE;
import static android.Manifest.permission.READ_CONTACTS;
import static com.android.internal.widget.LockPatternUtils.StrongAuthTracker.STRONG_AUTH_REQUIRED_AFTER_LOCKOUT;

import android.database.sqlite.SQLiteDatabase;
import android.os.Binder;
import android.os.IBinder;
import android.os.RemoteException;
import android.os.storage.IMountService;
import android.os.ServiceManager;
import android.os.SystemProperties;
import android.os.UserHandle;
import android.os.UserManager;
import android.provider.Settings;
import android.provider.Settings.Secure;
import android.provider.Settings.SettingNotFoundException;
import android.security.KeyStore;
import android.service.gatekeeper.GateKeeperResponse;
import android.service.gatekeeper.IGateKeeperService;
import android.text.TextUtils;
import android.util.Slog;

import com.android.internal.util.ArrayUtils;
import com.android.internal.widget.ILockSettings;
import com.android.internal.widget.LockPatternUtils;
import com.android.internal.widget.VerifyCredentialResponse;
import com.android.server.LockSettingsStorage.CredentialHash;

import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import java.util.Arrays;
import java.util.List;

/**
 * Keeps the lock pattern/password data and related settings for each user.
 * Used by LockPatternUtils. Needs to be a service because Settings app also needs
 * to be able to save lockscreen information for secondary users.
 * @hide
 */
public class LockSettingsService extends ILockSettings.Stub {
    private static final String TAG = "LockSettingsService";
    private static final String PERMISSION = ACCESS_KEYGUARD_SECURE_STORAGE;
    private static final Intent ACTION_NULL; // hack to ensure notification shows the bouncer
    private static final int FBE_ENCRYPTED_NOTIFICATION = 0;
    private static final boolean DEBUG = false;

    private final Context mContext;
    private final LockSettingsStorage mStorage;
    private final LockSettingsStrongAuth mStrongAuth;

    private LockPatternUtils mLockPatternUtils;
    private boolean mFirstCallToVold;
    private IGateKeeperService mGateKeeperService;
    private NotificationManager mNotificationManager;
    private UserManager mUserManager;

    static {
        // Just launch the home screen, which happens anyway
        ACTION_NULL = new Intent(Intent.ACTION_MAIN);
        ACTION_NULL.addCategory(Intent.CATEGORY_HOME);
    }

    private interface CredentialUtil {
        void setCredential(String credential, String savedCredential, int userId)
                throws RemoteException;
        byte[] toHash(String credential, int userId);
        String adjustForKeystore(String credential);
    }

    // This class manages life cycle events for encrypted users on File Based Encryption (FBE)
    // devices. The most basic of these is to show/hide notifications about missing features until
    // the user unlocks the account and credential-encrypted storage is available.
    public static final class Lifecycle extends SystemService {
        private LockSettingsService mLockSettingsService;

        public Lifecycle(Context context) {
            super(context);
        }

        @Override
        public void onStart() {
            mLockSettingsService = new LockSettingsService(getContext());
            publishBinderService("lock_settings", mLockSettingsService);
        }

        @Override
        public void onBootPhase(int phase) {
            if (phase == SystemService.PHASE_ACTIVITY_MANAGER_READY) {
                mLockSettingsService.maybeShowEncryptionNotifications();
            } else if (phase == SystemService.PHASE_BOOT_COMPLETED) {
                // TODO
            }
        }

        @Override
        public void onUnlockUser(int userHandle) {
            mLockSettingsService.onUnlockUser(userHandle);
        }

        @Override
        public void onCleanupUser(int userHandle) {
            mLockSettingsService.onCleanupUser(userHandle);
        }
    }

    public LockSettingsService(Context context) {
        mContext = context;
        mStrongAuth = new LockSettingsStrongAuth(context);
        // Open the database

        mLockPatternUtils = new LockPatternUtils(context);
        mFirstCallToVold = true;

        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_USER_ADDED);
        filter.addAction(Intent.ACTION_USER_STARTING);
        filter.addAction(Intent.ACTION_USER_REMOVED);
        filter.addAction(Intent.ACTION_USER_PRESENT);
        mContext.registerReceiverAsUser(mBroadcastReceiver, UserHandle.ALL, filter, null, null);

        mStorage = new LockSettingsStorage(context, new LockSettingsStorage.Callback() {
            @Override
            public void initialize(SQLiteDatabase db) {
                // Get the lockscreen default from a system property, if available
                boolean lockScreenDisable = SystemProperties.getBoolean(
                        "ro.lockscreen.disable.default", false);
                if (lockScreenDisable) {
                    mStorage.writeKeyValue(db, LockPatternUtils.DISABLE_LOCKSCREEN_KEY, "1", 0);
                }
            }
        });
        mNotificationManager = (NotificationManager)
                mContext.getSystemService(Context.NOTIFICATION_SERVICE);
        mUserManager = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
    }

    /**
     * If the account is credential-encrypted, show notification requesting the user to unlock
     * the device.
     */
    private void maybeShowEncryptionNotifications() {
        final List<UserInfo> users = mUserManager.getUsers();
        for (int i = 0; i < users.size(); i++) {
            UserInfo user = users.get(i);
            UserHandle userHandle = user.getUserHandle();
            if (!mUserManager.isUserUnlocked(userHandle)) {
                if (!user.isManagedProfile()) {
                    showEncryptionNotification(userHandle);
                } else {
                    UserInfo parent = mUserManager.getProfileParent(user.id);
                    if (parent != null && mUserManager.isUserUnlocked(parent.getUserHandle())) {
                        // Only show notifications for managed profiles once their parent
                        // user is unlocked.
                        showEncryptionNotificationForProfile(userHandle);
                    }
                }
            }
        }
    }

    private void showEncryptionNotificationForProfile(UserHandle user) {
        Resources r = mContext.getResources();
        CharSequence title = r.getText(
                com.android.internal.R.string.user_encrypted_title);
        CharSequence message = r.getText(
                com.android.internal.R.string.profile_encrypted_message);
        CharSequence detail = r.getText(
                com.android.internal.R.string.profile_encrypted_detail);

        final KeyguardManager km = (KeyguardManager) mContext.getSystemService(KEYGUARD_SERVICE);
        final Intent unlockIntent = km.createConfirmDeviceCredentialIntent(null, null, user.getIdentifier());
        if (unlockIntent == null) {
            return;
        }
        unlockIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
        PendingIntent intent = PendingIntent.getActivity(mContext, 0, unlockIntent,
                PendingIntent.FLAG_UPDATE_CURRENT);

        showEncryptionNotification(user, title, message, detail, intent);
    }

    private void showEncryptionNotification(UserHandle user) {
        Resources r = mContext.getResources();
        CharSequence title = r.getText(
                com.android.internal.R.string.user_encrypted_title);
        CharSequence message = r.getText(
                com.android.internal.R.string.user_encrypted_message);
        CharSequence detail = r.getText(
                com.android.internal.R.string.user_encrypted_detail);

        PendingIntent intent = PendingIntent.getBroadcast(mContext, 0, ACTION_NULL,
                PendingIntent.FLAG_UPDATE_CURRENT);

        showEncryptionNotification(user, title, message, detail, intent);
    }

    private void showEncryptionNotification(UserHandle user, CharSequence title, CharSequence message,
            CharSequence detail, PendingIntent intent) {
        if (DEBUG) Slog.v(TAG, "showing encryption notification, user: " + user.getIdentifier());
        Notification notification = new Notification.Builder(mContext)
                .setSmallIcon(com.android.internal.R.drawable.ic_user_secure)
                .setWhen(0)
                .setOngoing(true)
                .setTicker(title)
                .setDefaults(0)  // please be quiet
                .setPriority(Notification.PRIORITY_MAX)
                .setColor(mContext.getColor(
                        com.android.internal.R.color.system_notification_accent_color))
                .setContentTitle(title)
                .setContentText(message)
                .setContentInfo(detail)
                .setVisibility(Notification.VISIBILITY_PUBLIC)
                .setContentIntent(intent)
                .build();
        mNotificationManager.notifyAsUser(null, FBE_ENCRYPTED_NOTIFICATION, notification, user);
    }

    public void hideEncryptionNotification(UserHandle userHandle) {
        if (DEBUG) Slog.v(TAG, "hide encryption notification, user: "+ userHandle.getIdentifier());
        mNotificationManager.cancelAsUser(null, FBE_ENCRYPTED_NOTIFICATION, userHandle);
    }

    public void onCleanupUser(int userId) {
        hideEncryptionNotification(new UserHandle(userId));
    }

    public void onUnlockUser(int userId) {
        hideEncryptionNotification(new UserHandle(userId));

        // Now we have unlocked the parent user we should show notifications
        // about any profiles that exist.
        List<UserInfo> profiles = mUserManager.getProfiles(userId);
        for (int i = 0; i < profiles.size(); i++) {
            UserInfo profile = profiles.get(i);
            if (profile.isManagedProfile()) {
                UserHandle userHandle = profile.getUserHandle();
                if (!mUserManager.isUserUnlocked(userHandle)) {
                    showEncryptionNotificationForProfile(userHandle);
                }
            }
        }
    }

    private final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (Intent.ACTION_USER_ADDED.equals(intent.getAction())) {
                // Notify keystore that a new user was added.
                final int userHandle = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0);
                final KeyStore ks = KeyStore.getInstance();
                final UserManager um = (UserManager) mContext.getSystemService(USER_SERVICE);
                final UserInfo parentInfo = um.getProfileParent(userHandle);
                final int parentHandle = parentInfo != null ? parentInfo.id : -1;
                ks.onUserAdded(userHandle, parentHandle);
            } else if (Intent.ACTION_USER_STARTING.equals(intent.getAction())) {
                final int userHandle = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0);
                mStorage.prefetchUser(userHandle);
            } else if (Intent.ACTION_USER_PRESENT.equals(intent.getAction())) {
                mStrongAuth.reportUnlock(getSendingUserId());
            } else if (Intent.ACTION_USER_REMOVED.equals(intent.getAction())) {
                final int userHandle = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, 0);
                if (userHandle > 0) {
                    removeUser(userHandle);
                }
            }
        }
    };

    @Override // binder interface
    public void systemReady() {
        migrateOldData();
        try {
            getGateKeeperService();
        } catch (RemoteException e) {
            Slog.e(TAG, "Failure retrieving IGateKeeperService", e);
        }
        // TODO: maybe skip this for split system user mode.
        mStorage.prefetchUser(UserHandle.USER_SYSTEM);
    }

    private void migrateOldData() {
        try {
            // These Settings moved before multi-user was enabled, so we only have to do it for the
            // root user.
            if (getString("migrated", null, 0) == null) {
                final ContentResolver cr = mContext.getContentResolver();
                for (String validSetting : VALID_SETTINGS) {
                    String value = Settings.Secure.getString(cr, validSetting);
                    if (value != null) {
                        setString(validSetting, value, 0);
                    }
                }
                // No need to move the password / pattern files. They're already in the right place.
                setString("migrated", "true", 0);
                Slog.i(TAG, "Migrated lock settings to new location");
            }

            // These Settings changed after multi-user was enabled, hence need to be moved per user.
            if (getString("migrated_user_specific", null, 0) == null) {
                final UserManager um = (UserManager) mContext.getSystemService(USER_SERVICE);
                final ContentResolver cr = mContext.getContentResolver();
                List<UserInfo> users = um.getUsers();
                for (int user = 0; user < users.size(); user++) {
                    // Migrate owner info
                    final int userId = users.get(user).id;
                    final String OWNER_INFO = Secure.LOCK_SCREEN_OWNER_INFO;
                    String ownerInfo = Settings.Secure.getStringForUser(cr, OWNER_INFO, userId);
                    if (ownerInfo != null) {
                        setString(OWNER_INFO, ownerInfo, userId);
                        Settings.Secure.putStringForUser(cr, ownerInfo, "", userId);
                    }

                    // Migrate owner info enabled.  Note there was a bug where older platforms only
                    // stored this value if the checkbox was toggled at least once. The code detects
                    // this case by handling the exception.
                    final String OWNER_INFO_ENABLED = Secure.LOCK_SCREEN_OWNER_INFO_ENABLED;
                    boolean enabled;
                    try {
                        int ivalue = Settings.Secure.getIntForUser(cr, OWNER_INFO_ENABLED, userId);
                        enabled = ivalue != 0;
                        setLong(OWNER_INFO_ENABLED, enabled ? 1 : 0, userId);
                    } catch (SettingNotFoundException e) {
                        // Setting was never stored. Store it if the string is not empty.
                        if (!TextUtils.isEmpty(ownerInfo)) {
                            setLong(OWNER_INFO_ENABLED, 1, userId);
                        }
                    }
                    Settings.Secure.putIntForUser(cr, OWNER_INFO_ENABLED, 0, userId);
                }
                // No need to move the password / pattern files. They're already in the right place.
                setString("migrated_user_specific", "true", 0);
                Slog.i(TAG, "Migrated per-user lock settings to new location");
            }

            // Migrates biometric weak such that the fallback mechanism becomes the primary.
            if (getString("migrated_biometric_weak", null, 0) == null) {
                final UserManager um = (UserManager) mContext.getSystemService(USER_SERVICE);
                List<UserInfo> users = um.getUsers();
                for (int i = 0; i < users.size(); i++) {
                    int userId = users.get(i).id;
                    long type = getLong(LockPatternUtils.PASSWORD_TYPE_KEY,
                            DevicePolicyManager.PASSWORD_QUALITY_UNSPECIFIED,
                            userId);
                    long alternateType = getLong(LockPatternUtils.PASSWORD_TYPE_ALTERNATE_KEY,
                            DevicePolicyManager.PASSWORD_QUALITY_UNSPECIFIED,
                            userId);
                    if (type == DevicePolicyManager.PASSWORD_QUALITY_BIOMETRIC_WEAK) {
                        setLong(LockPatternUtils.PASSWORD_TYPE_KEY,
                                alternateType,
                                userId);
                    }
                    setLong(LockPatternUtils.PASSWORD_TYPE_ALTERNATE_KEY,
                            DevicePolicyManager.PASSWORD_QUALITY_UNSPECIFIED,
                            userId);
                }
                setString("migrated_biometric_weak", "true", 0);
                Slog.i(TAG, "Migrated biometric weak to use the fallback instead");
            }

            // Migrates lockscreen.disabled. Prior to M, the flag was ignored when more than one
            // user was present on the system, so if we're upgrading to M and there is more than one
            // user we disable the flag to remain consistent.
            if (getString("migrated_lockscreen_disabled", null, 0) == null) {
                final UserManager um = (UserManager) mContext.getSystemService(USER_SERVICE);

                final List<UserInfo> users = um.getUsers();
                final int userCount = users.size();
                int switchableUsers = 0;
                for (int i = 0; i < userCount; i++) {
                    if (users.get(i).supportsSwitchTo()) {
                        switchableUsers++;
                    }
                }

                if (switchableUsers > 1) {
                    for (int i = 0; i < userCount; i++) {
                        int id = users.get(i).id;

                        if (getBoolean(LockPatternUtils.DISABLE_LOCKSCREEN_KEY, false, id)) {
                            setBoolean(LockPatternUtils.DISABLE_LOCKSCREEN_KEY, false, id);
                        }
                    }
                }

                setString("migrated_lockscreen_disabled", "true", 0);
                Slog.i(TAG, "Migrated lockscreen disabled flag");
            }
        } catch (RemoteException re) {
            Slog.e(TAG, "Unable to migrate old data", re);
        }
    }

    private final void checkWritePermission(int userId) {
        mContext.enforceCallingOrSelfPermission(PERMISSION, "LockSettingsWrite");
    }

    private final void checkPasswordReadPermission(int userId) {
        mContext.enforceCallingOrSelfPermission(PERMISSION, "LockSettingsRead");
    }

    private final void checkReadPermission(String requestedKey, int userId) {
        final int callingUid = Binder.getCallingUid();

        for (int i = 0; i < READ_CONTACTS_PROTECTED_SETTINGS.length; i++) {
            String key = READ_CONTACTS_PROTECTED_SETTINGS[i];
            if (key.equals(requestedKey) && mContext.checkCallingOrSelfPermission(READ_CONTACTS)
                    != PackageManager.PERMISSION_GRANTED) {
                throw new SecurityException("uid=" + callingUid
                        + " needs permission " + READ_CONTACTS + " to read "
                        + requestedKey + " for user " + userId);
            }
        }

        for (int i = 0; i < READ_PASSWORD_PROTECTED_SETTINGS.length; i++) {
            String key = READ_PASSWORD_PROTECTED_SETTINGS[i];
            if (key.equals(requestedKey) && mContext.checkCallingOrSelfPermission(PERMISSION)
                    != PackageManager.PERMISSION_GRANTED) {
                throw new SecurityException("uid=" + callingUid
                        + " needs permission " + PERMISSION + " to read "
                        + requestedKey + " for user " + userId);
            }
        }
    }

    @Override
    public void setBoolean(String key, boolean value, int userId) throws RemoteException {
        checkWritePermission(userId);
        setStringUnchecked(key, userId, value ? "1" : "0");
    }

    @Override
    public void setLong(String key, long value, int userId) throws RemoteException {
        checkWritePermission(userId);
        setStringUnchecked(key, userId, Long.toString(value));
    }

    @Override
    public void setString(String key, String value, int userId) throws RemoteException {
        checkWritePermission(userId);
        setStringUnchecked(key, userId, value);
    }

    private void setStringUnchecked(String key, int userId, String value) {
        mStorage.writeKeyValue(key, value, userId);
        if (ArrayUtils.contains(SETTINGS_TO_BACKUP, key)) {
            BackupManager.dataChanged("com.android.providers.settings");
        }
    }

    @Override
    public boolean getBoolean(String key, boolean defaultValue, int userId) throws RemoteException {
        checkReadPermission(key, userId);
        String value = getStringUnchecked(key, null, userId);
        return TextUtils.isEmpty(value) ?
                defaultValue : (value.equals("1") || value.equals("true"));
    }

    @Override
    public long getLong(String key, long defaultValue, int userId) throws RemoteException {
        checkReadPermission(key, userId);

        String value = getStringUnchecked(key, null, userId);
        return TextUtils.isEmpty(value) ? defaultValue : Long.parseLong(value);
    }

    @Override
    public String getString(String key, String defaultValue, int userId) throws RemoteException {
        checkReadPermission(key, userId);

        return getStringUnchecked(key, defaultValue, userId);
    }

    public String getStringUnchecked(String key, String defaultValue, int userId) {
        if (Settings.Secure.LOCK_PATTERN_ENABLED.equals(key)) {
            long ident = Binder.clearCallingIdentity();
            try {
                return mLockPatternUtils.isLockPatternEnabled(userId) ? "1" : "0";
            } finally {
                Binder.restoreCallingIdentity(ident);
            }
        }

        if (LockPatternUtils.LEGACY_LOCK_PATTERN_ENABLED.equals(key)) {
            key = Settings.Secure.LOCK_PATTERN_ENABLED;
        }

        return mStorage.readKeyValue(key, defaultValue, userId);
    }

    @Override
    public boolean havePassword(int userId) throws RemoteException {
        // Do we need a permissions check here?

        return mStorage.hasPassword(userId);
    }

    @Override
    public boolean havePattern(int userId) throws RemoteException {
        // Do we need a permissions check here?

        return mStorage.hasPattern(userId);
    }

    private void setKeystorePassword(String password, int userHandle) {
        final UserManager um = (UserManager) mContext.getSystemService(USER_SERVICE);
        final KeyStore ks = KeyStore.getInstance();

        final List<UserInfo> profiles = um.getProfiles(userHandle);
        for (UserInfo pi : profiles) {
            ks.onUserPasswordChanged(pi.id, password);
        }
    }

    private void unlockKeystore(String password, int userHandle) {
        final UserManager um = (UserManager) mContext.getSystemService(USER_SERVICE);
        final KeyStore ks = KeyStore.getInstance();

        final List<UserInfo> profiles = um.getProfiles(userHandle);
        for (UserInfo pi : profiles) {
            ks.unlock(pi.id, password);
        }
    }

    private void unlockUser(int userId, byte[] token, byte[] secret) {
        try {
            ActivityManagerNative.getDefault().unlockUser(userId, token, secret);
        } catch (RemoteException e) {
            throw e.rethrowAsRuntimeException();
        }
    }

    private byte[] getCurrentHandle(int userId) {
        CredentialHash credential;
        byte[] currentHandle;

        int currentHandleType = mStorage.getStoredCredentialType(userId);
        switch (currentHandleType) {
            case CredentialHash.TYPE_PATTERN:
                credential = mStorage.readPatternHash(userId);
                currentHandle = credential != null
                        ? credential.hash
                        : null;
                break;
            case CredentialHash.TYPE_PASSWORD:
                credential = mStorage.readPasswordHash(userId);
                currentHandle = credential != null
                        ? credential.hash
                        : null;
                break;
            case CredentialHash.TYPE_NONE:
            default:
                currentHandle = null;
                break;
        }

        // sanity check
        if (currentHandleType != CredentialHash.TYPE_NONE && currentHandle == null) {
            Slog.e(TAG, "Stored handle type [" + currentHandleType + "] but no handle available");
        }

        return currentHandle;
    }


    @Override
    public void setLockPattern(String pattern, String savedCredential, int userId)
            throws RemoteException {
        byte[] currentHandle = getCurrentHandle(userId);

        if (pattern == null) {
            getGateKeeperService().clearSecureUserId(userId);
            mStorage.writePatternHash(null, userId);
            setKeystorePassword(null, userId);
            clearUserKeyProtection(userId);
            return;
        }

        if (currentHandle == null) {
            if (savedCredential != null) {
                Slog.w(TAG, "Saved credential provided, but none stored");
            }
            savedCredential = null;
        }

        byte[] enrolledHandle = enrollCredential(currentHandle, savedCredential, pattern, userId);
        if (enrolledHandle != null) {
            mStorage.writePatternHash(enrolledHandle, userId);
            setUserKeyProtection(userId, pattern, verifyPattern(pattern, 0, userId));
        } else {
            throw new RemoteException("Failed to enroll pattern");
        }
    }


    @Override
    public void setLockPassword(String password, String savedCredential, int userId)
            throws RemoteException {
        byte[] currentHandle = getCurrentHandle(userId);

        if (password == null) {
            getGateKeeperService().clearSecureUserId(userId);
            mStorage.writePasswordHash(null, userId);
            setKeystorePassword(null, userId);
            clearUserKeyProtection(userId);
            return;
        }

        if (currentHandle == null) {
            if (savedCredential != null) {
                Slog.w(TAG, "Saved credential provided, but none stored");
            }
            savedCredential = null;
        }

        byte[] enrolledHandle = enrollCredential(currentHandle, savedCredential, password, userId);
        if (enrolledHandle != null) {
            mStorage.writePasswordHash(enrolledHandle, userId);
            setUserKeyProtection(userId, password, verifyPassword(password, 0, userId));
        } else {
            throw new RemoteException("Failed to enroll password");
        }
    }

    private byte[] enrollCredential(byte[] enrolledHandle,
            String enrolledCredential, String toEnroll, int userId)
            throws RemoteException {
        checkWritePermission(userId);
        byte[] enrolledCredentialBytes = enrolledCredential == null
                ? null
                : enrolledCredential.getBytes();
        byte[] toEnrollBytes = toEnroll == null
                ? null
                : toEnroll.getBytes();
        GateKeeperResponse response = getGateKeeperService().enroll(userId, enrolledHandle,
                enrolledCredentialBytes, toEnrollBytes);

        if (response == null) {
            return null;
        }

        byte[] hash = response.getPayload();
        if (hash != null) {
            setKeystorePassword(toEnroll, userId);
        } else {
            // Should not happen
            Slog.e(TAG, "Throttled while enrolling a password");
        }
        return hash;
    }

    private void setUserKeyProtection(int userId, String credential, VerifyCredentialResponse vcr)
            throws RemoteException {
        if (vcr == null) {
            throw new RemoteException("Null response verifying a credential we just set");
        }
        if (vcr.getResponseCode() != VerifyCredentialResponse.RESPONSE_OK) {
            throw new RemoteException("Non-OK response verifying a credential we just set: "
                + vcr.getResponseCode());
        }
        byte[] token = vcr.getPayload();
        if (token == null) {
            throw new RemoteException("Empty payload verifying a credential we just set");
        }
        changeUserKey(userId, token, secretFromCredential(credential));
    }

    private void clearUserKeyProtection(int userId) throws RemoteException {
        changeUserKey(userId, null, null);
    }

    private static byte[] secretFromCredential(String credential) throws RemoteException {
        try {
            MessageDigest digest = MessageDigest.getInstance("SHA-512");
            // Personalize the hash
            byte[] personalization = "Android FBE credential hash"
                    .getBytes(StandardCharsets.UTF_8);
            // Pad it to the block size of the hash function
            personalization = Arrays.copyOf(personalization, 128);
            digest.update(personalization);
            digest.update(credential.getBytes(StandardCharsets.UTF_8));
            return digest.digest();
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("NoSuchAlgorithmException for SHA-512");
        }
    }

    private void changeUserKey(int userId, byte[] token, byte[] secret)
            throws RemoteException {
        final UserInfo userInfo = UserManager.get(mContext).getUserInfo(userId);
        getMountService().changeUserKey(userId, userInfo.serialNumber, token, null, secret);
    }

    @Override
    public VerifyCredentialResponse checkPattern(String pattern, int userId) throws RemoteException {
        return doVerifyPattern(pattern, false, 0, userId);
    }

    @Override
    public VerifyCredentialResponse verifyPattern(String pattern, long challenge, int userId)
            throws RemoteException {
        return doVerifyPattern(pattern, true, challenge, userId);
    }

    private VerifyCredentialResponse doVerifyPattern(String pattern, boolean hasChallenge,
            long challenge, int userId) throws RemoteException {
       checkPasswordReadPermission(userId);
       CredentialHash storedHash = mStorage.readPatternHash(userId);
       boolean shouldReEnrollBaseZero = storedHash != null && storedHash.isBaseZeroPattern;

       String patternToVerify;
       if (shouldReEnrollBaseZero) {
           patternToVerify = LockPatternUtils.patternStringToBaseZero(pattern);
       } else {
           patternToVerify = pattern;
       }

       VerifyCredentialResponse response = verifyCredential(userId, storedHash, patternToVerify,
               hasChallenge, challenge,
               new CredentialUtil() {
                   @Override
                   public void setCredential(String pattern, String oldPattern, int userId)
                           throws RemoteException {
                       setLockPattern(pattern, oldPattern, userId);
                   }

                   @Override
                   public byte[] toHash(String pattern, int userId) {
                       return LockPatternUtils.patternToHash(
                               LockPatternUtils.stringToPattern(pattern));
                   }

                   @Override
                   public String adjustForKeystore(String pattern) {
                       return LockPatternUtils.patternStringToBaseZero(pattern);
                   }
               }
       );

       if (response.getResponseCode() == VerifyCredentialResponse.RESPONSE_OK
               && shouldReEnrollBaseZero) {
           setLockPattern(pattern, patternToVerify, userId);
       }

       return response;

    }

    @Override
    public VerifyCredentialResponse checkPassword(String password, int userId)
            throws RemoteException {
        return doVerifyPassword(password, false, 0, userId);
    }

    @Override
    public VerifyCredentialResponse verifyPassword(String password, long challenge, int userId)
            throws RemoteException {
        return doVerifyPassword(password, true, challenge, userId);
    }

    private VerifyCredentialResponse doVerifyPassword(String password, boolean hasChallenge,
            long challenge, int userId) throws RemoteException {
       checkPasswordReadPermission(userId);
       CredentialHash storedHash = mStorage.readPasswordHash(userId);
       return verifyCredential(userId, storedHash, password, hasChallenge, challenge,
               new CredentialUtil() {
                   @Override
                   public void setCredential(String password, String oldPassword, int userId)
                           throws RemoteException {
                       setLockPassword(password, oldPassword, userId);
                   }

                   @Override
                   public byte[] toHash(String password, int userId) {
                       return mLockPatternUtils.passwordToHash(password, userId);
                   }

                   @Override
                   public String adjustForKeystore(String password) {
                       return password;
                   }
               }
       );
    }

    private VerifyCredentialResponse verifyCredential(int userId, CredentialHash storedHash,
            String credential, boolean hasChallenge, long challenge, CredentialUtil credentialUtil)
                throws RemoteException {
        if ((storedHash == null || storedHash.hash.length == 0) && TextUtils.isEmpty(credential)) {
            // don't need to pass empty credentials to GateKeeper
            return VerifyCredentialResponse.OK;
        }

        if (TextUtils.isEmpty(credential)) {
            return VerifyCredentialResponse.ERROR;
        }

        if (storedHash.version == CredentialHash.VERSION_LEGACY) {
            byte[] hash = credentialUtil.toHash(credential, userId);
            if (Arrays.equals(hash, storedHash.hash)) {
                unlockKeystore(credentialUtil.adjustForKeystore(credential), userId);

                // Users with legacy credentials don't have credential-backed
                // FBE keys, so just pass through a fake token/secret
                Slog.i(TAG, "Unlocking user with fake token: " + userId);
                final byte[] fakeToken = String.valueOf(userId).getBytes();
                unlockUser(userId, fakeToken, fakeToken);

                // migrate credential to GateKeeper
                credentialUtil.setCredential(credential, null, userId);
                if (!hasChallenge) {
                    return VerifyCredentialResponse.OK;
                }
                // Fall through to get the auth token. Technically this should never happen,
                // as a user that had a legacy credential would have to unlock their device
                // before getting to a flow with a challenge, but supporting for consistency.
            } else {
                return VerifyCredentialResponse.ERROR;
            }
        }

        VerifyCredentialResponse response;
        boolean shouldReEnroll = false;
        GateKeeperResponse gateKeeperResponse = getGateKeeperService()
                .verifyChallenge(userId, challenge, storedHash.hash, credential.getBytes());
        int responseCode = gateKeeperResponse.getResponseCode();
        if (responseCode == GateKeeperResponse.RESPONSE_RETRY) {
             response = new VerifyCredentialResponse(gateKeeperResponse.getTimeout());
        } else if (responseCode == GateKeeperResponse.RESPONSE_OK) {
            byte[] token = gateKeeperResponse.getPayload();
            if (token == null) {
                // something's wrong if there's no payload with a challenge
                Slog.e(TAG, "verifyChallenge response had no associated payload");
                response = VerifyCredentialResponse.ERROR;
            } else {
                shouldReEnroll = gateKeeperResponse.getShouldReEnroll();
                response = new VerifyCredentialResponse(token);
            }
        } else {
            response = VerifyCredentialResponse.ERROR;
        }

        if (response.getResponseCode() == VerifyCredentialResponse.RESPONSE_OK) {
            // credential has matched
            unlockKeystore(credential, userId);

            Slog.i(TAG, "Unlocking user " + userId +
                " with token length " + response.getPayload().length);
            unlockUser(userId, response.getPayload(), secretFromCredential(credential));

            UserInfo info = UserManager.get(mContext).getUserInfo(userId);
            if (mLockPatternUtils.isSeparateProfileChallengeEnabled(userId)) {
                TrustManager trustManager =
                        (TrustManager) mContext.getSystemService(Context.TRUST_SERVICE);
                trustManager.setDeviceLockedForUser(userId, false);
            }
            if (shouldReEnroll) {
                credentialUtil.setCredential(credential, credential, userId);
            }
        } else if (response.getResponseCode() == VerifyCredentialResponse.RESPONSE_RETRY) {
            if (response.getTimeout() > 0) {
                requireStrongAuth(STRONG_AUTH_REQUIRED_AFTER_LOCKOUT, userId);
            }
        }

        return response;
    }

    @Override
    public boolean checkVoldPassword(int userId) throws RemoteException {
        if (!mFirstCallToVold) {
            return false;
        }
        mFirstCallToVold = false;

        checkPasswordReadPermission(userId);

        // There's no guarantee that this will safely connect, but if it fails
        // we will simply show the lock screen when we shouldn't, so relatively
        // benign. There is an outside chance something nasty would happen if
        // this service restarted before vold stales out the password in this
        // case. The nastiness is limited to not showing the lock screen when
        // we should, within the first minute of decrypting the phone if this
        // service can't connect to vold, it restarts, and then the new instance
        // does successfully connect.
        final IMountService service = getMountService();
        String password = service.getPassword();
        service.clearPassword();
        if (password == null) {
            return false;
        }

        try {
            if (mLockPatternUtils.isLockPatternEnabled(userId)) {
                if (checkPattern(password, userId).getResponseCode()
                        == GateKeeperResponse.RESPONSE_OK) {
                    return true;
                }
            }
        } catch (Exception e) {
        }

        try {
            if (mLockPatternUtils.isLockPasswordEnabled(userId)) {
                if (checkPassword(password, userId).getResponseCode()
                        == GateKeeperResponse.RESPONSE_OK) {
                    return true;
                }
            }
        } catch (Exception e) {
        }

        return false;
    }

    private void removeUser(int userId) {
        mStorage.removeUser(userId);
        mStrongAuth.removeUser(userId);

        final KeyStore ks = KeyStore.getInstance();
        ks.onUserRemoved(userId);

        try {
            final IGateKeeperService gk = getGateKeeperService();
            if (gk != null) {
                    gk.clearSecureUserId(userId);
            }
        } catch (RemoteException ex) {
            Slog.w(TAG, "unable to clear GK secure user id");
        }
    }

    @Override
    public void registerStrongAuthTracker(IStrongAuthTracker tracker) {
        checkPasswordReadPermission(UserHandle.USER_ALL);
        mStrongAuth.registerStrongAuthTracker(tracker);
    }

    @Override
    public void unregisterStrongAuthTracker(IStrongAuthTracker tracker) {
        checkPasswordReadPermission(UserHandle.USER_ALL);
        mStrongAuth.unregisterStrongAuthTracker(tracker);
    }

    @Override
    public void requireStrongAuth(int strongAuthReason, int userId) {
        checkWritePermission(userId);
        mStrongAuth.requireStrongAuth(strongAuthReason, userId);
    }

    private static final String[] VALID_SETTINGS = new String[] {
        LockPatternUtils.LOCKOUT_PERMANENT_KEY,
        LockPatternUtils.LOCKOUT_ATTEMPT_DEADLINE,
        LockPatternUtils.PATTERN_EVER_CHOSEN_KEY,
        LockPatternUtils.PASSWORD_TYPE_KEY,
        LockPatternUtils.PASSWORD_TYPE_ALTERNATE_KEY,
        LockPatternUtils.LOCK_PASSWORD_SALT_KEY,
        LockPatternUtils.DISABLE_LOCKSCREEN_KEY,
        LockPatternUtils.LOCKSCREEN_OPTIONS,
        LockPatternUtils.LOCKSCREEN_BIOMETRIC_WEAK_FALLBACK,
        LockPatternUtils.BIOMETRIC_WEAK_EVER_CHOSEN_KEY,
        LockPatternUtils.LOCKSCREEN_POWER_BUTTON_INSTANTLY_LOCKS,
        LockPatternUtils.PASSWORD_HISTORY_KEY,
        Secure.LOCK_PATTERN_ENABLED,
        Secure.LOCK_BIOMETRIC_WEAK_FLAGS,
        Secure.LOCK_PATTERN_VISIBLE,
        Secure.LOCK_PATTERN_TACTILE_FEEDBACK_ENABLED
    };

    // Reading these settings needs the contacts permission
    private static final String[] READ_CONTACTS_PROTECTED_SETTINGS = new String[] {
        Secure.LOCK_SCREEN_OWNER_INFO_ENABLED,
        Secure.LOCK_SCREEN_OWNER_INFO
    };

    // Reading these settings needs the same permission as checking the password
    private static final String[] READ_PASSWORD_PROTECTED_SETTINGS = new String[] {
            LockPatternUtils.LOCK_PASSWORD_SALT_KEY,
            LockPatternUtils.PASSWORD_HISTORY_KEY,
            LockPatternUtils.PASSWORD_TYPE_KEY,
    };

    private static final String[] SETTINGS_TO_BACKUP = new String[] {
        Secure.LOCK_SCREEN_OWNER_INFO_ENABLED,
        Secure.LOCK_SCREEN_OWNER_INFO
    };

    private IMountService getMountService() {
        final IBinder service = ServiceManager.getService("mount");
        if (service != null) {
            return IMountService.Stub.asInterface(service);
        }
        return null;
    }

    private class GateKeeperDiedRecipient implements IBinder.DeathRecipient {
        @Override
        public void binderDied() {
            mGateKeeperService.asBinder().unlinkToDeath(this, 0);
            mGateKeeperService = null;
        }
    }

    private synchronized IGateKeeperService getGateKeeperService()
            throws RemoteException {
        if (mGateKeeperService != null) {
            return mGateKeeperService;
        }

        final IBinder service =
            ServiceManager.getService("android.service.gatekeeper.IGateKeeperService");
        if (service != null) {
            service.linkToDeath(new GateKeeperDiedRecipient(), 0);
            mGateKeeperService = IGateKeeperService.Stub.asInterface(service);
            return mGateKeeperService;
        }

        Slog.e(TAG, "Unable to acquire GateKeeperService");
        return null;
    }
}