Building support for IMSI encryption. (f36f94a9) · Commits · e / os / android_frameworks_opt_telephony

src/java/com/android/internal/telephony/CarrierKeyDownloadManager.java

0 → 100644

+471 −0

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		/*
		* Copyright (C) 2017 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.internal.telephony;

		import static android.preference.PreferenceManager.getDefaultSharedPreferences;

		import android.app.AlarmManager;
		import android.app.DownloadManager;
		import android.app.PendingIntent;
		import android.content.BroadcastReceiver;
		import android.content.Context;
		import android.content.Intent;
		import android.content.IntentFilter;
		import android.content.SharedPreferences;
		import android.database.Cursor;
		import android.net.Uri;
		import android.os.PersistableBundle;
		import android.telephony.CarrierConfigManager;
		import android.telephony.ImsiEncryptionInfo;
		import android.telephony.SubscriptionManager;
		import android.telephony.TelephonyManager;
		import android.text.TextUtils;
		import android.util.Base64;
		import android.util.Log;

		import com.android.internal.annotations.VisibleForTesting;

		import org.json.JSONArray;
		import org.json.JSONException;
		import org.json.JSONObject;

		import java.io.BufferedReader;
		import java.io.FileInputStream;
		import java.io.IOException;
		import java.io.InputStream;
		import java.io.InputStreamReader;
		import java.util.Date;

		/**
		* This class contains logic to get Certificates and keep them current.
		* The class will be instantiated by various Phone implementations.
		*/
		public class CarrierKeyDownloadManager {
		private static final String LOG_TAG = "CarrierKeyDownloadManager";

		private static final String MCC_MNC_PREF_TAG = "CARRIER_KEY_DM_MCC_MNC";

		private static final int DAY_IN_MILLIS = 24 * 3600 * 1000;

		// Start trying to renew the cert X days before it expires.
		private static final int DEFAULT_RENEWAL_WINDOW_DAYS = 7;

		/* Intent for downloading the public key */
		private static final String INTENT_KEY_RENEWAL_ALARM_PREFIX =
		"com.android.internal.telephony.carrier_key_download_alarm";

		private int mKeyAvailability = 0;

		public static final String MNC = "MNC";
		public static final String MCC = "MCC";
		private static final String SEPARATOR = ":";

		private static final String JSON_KEY = "key";
		private static final String JSON_TYPE = "type";
		private static final String JSON_IDENTIFIER = "identifier";
		private static final String JSON_EXPIRATION_DATE = "expiration-date";
		private static final String JSON_CARRIER_KEYS = "carrier-keys";
		private static final String JSON_TYPE_VALUE_WLAN = "WLAN";
		private static final String JSON_TYPE_VALUE_EPDG = "EPDG";


		private static final int[] CARRIER_KEY_TYPES = {TelephonyManager.KEY_TYPE_EPDG,
		TelephonyManager.KEY_TYPE_WLAN};
		private static final int UNINITIALIZED_KEY_TYPE = -1;

		private final Phone mPhone;
		private final Context mContext;
		private final DownloadManager mDownloadManager;
		private String mURL;

		public CarrierKeyDownloadManager(Phone phone) {
		mPhone = phone;
		mContext = phone.getContext();
		IntentFilter filter = new IntentFilter();
		filter.addAction(CarrierConfigManager.ACTION_CARRIER_CONFIG_CHANGED);
		filter.addAction(DownloadManager.ACTION_DOWNLOAD_COMPLETE);
		filter.addAction(INTENT_KEY_RENEWAL_ALARM_PREFIX + mPhone.getPhoneId());
		mContext.registerReceiver(mBroadcastReceiver, filter, null, phone);
		mDownloadManager = (DownloadManager) mContext.getSystemService(Context.DOWNLOAD_SERVICE);
		}

		private final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
		@Override
		public void onReceive(Context context, Intent intent) {
		String action = intent.getAction();
		int slotId = mPhone.getPhoneId();
		if (action.equals(INTENT_KEY_RENEWAL_ALARM_PREFIX + slotId)) {
		Log.d(LOG_TAG, "Handling key renewal alarm: " + action);
		handleAlarmOrConfigChange();
		} else if (action.equals(CarrierConfigManager.ACTION_CARRIER_CONFIG_CHANGED)) {
		if (slotId == intent.getIntExtra(PhoneConstants.PHONE_KEY,
		SubscriptionManager.INVALID_SIM_SLOT_INDEX)) {
		Log.d(LOG_TAG, "Carrier Config changed: " + action);
		handleAlarmOrConfigChange();
		}
		} else if (action.equals(DownloadManager.ACTION_DOWNLOAD_COMPLETE)) {
		Log.d(LOG_TAG, "Download Complete");
		long carrierKeyDownloadIdentifier =
		intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, 0);
		String mccMnc = getMccMncSetFromPref();
		if (isValidDownload(mccMnc)) {
		onDownloadComplete(carrierKeyDownloadIdentifier, mccMnc);
		onPostDownloadProcessing(carrierKeyDownloadIdentifier);
		}
		}
		}
		};

		private void onPostDownloadProcessing(long carrierKeyDownloadIdentifier) {
		resetRenewalAlarm();
		cleanupDownloadPreferences(carrierKeyDownloadIdentifier);
		}

		private void handleAlarmOrConfigChange() {
		if (carrierUsesKeys()) {
		if (areCarrierKeysAbsentOrExpiring()) {
		boolean downloadStartedSuccessfully = downloadKey();
		// if the download was attemped, but not started successfully, and if carriers uses
		// keys, we'll still want to renew the alarms, and try downloading the key a day
		// later.
		if (!downloadStartedSuccessfully) {
		resetRenewalAlarm();
		}
		} else {
		return;
		}
		} else {
		// delete any existing alarms.
		cleanupRenewalAlarms();
		}
		}

		private void cleanupDownloadPreferences(long carrierKeyDownloadIdentifier) {
		Log.d(LOG_TAG, "Cleaning up download preferences: " + carrierKeyDownloadIdentifier);
		SharedPreferences.Editor editor = getDefaultSharedPreferences(mContext).edit();
		editor.remove(String.valueOf(carrierKeyDownloadIdentifier));
		editor.commit();
		}

		private void cleanupRenewalAlarms() {
		Log.d(LOG_TAG, "Cleaning up existing renewal alarms");
		int slotId = mPhone.getPhoneId();
		Intent intent = new Intent(INTENT_KEY_RENEWAL_ALARM_PREFIX + slotId);
		PendingIntent carrierKeyDownloadIntent = PendingIntent.getBroadcast(mContext, 0, intent,
		PendingIntent.FLAG_UPDATE_CURRENT);
		AlarmManager alarmManager =
		(AlarmManager) mContext.getSystemService(mContext.ALARM_SERVICE);
		alarmManager.cancel(carrierKeyDownloadIntent);
		}

		/**
		* this method resets the alarm. Starts by cleaning up the existing alarms.
		* We look at the earliest expiration date, and setup an alarms X days prior.
		* If the expiration date is in the past, we'll setup an alarm to run the next day. This
		* could happen if the download has failed.
		**/
		private void resetRenewalAlarm() {
		cleanupRenewalAlarms();
		int slotId = mPhone.getPhoneId();
		long minExpirationDate = Long.MAX_VALUE;
		for (int key_type : CARRIER_KEY_TYPES) {
		if (!isKeyEnabled(key_type)) {
		continue;
		}
		ImsiEncryptionInfo imsiEncryptionInfo =
		mPhone.getCarrierInfoForImsiEncryption(key_type);
		if (imsiEncryptionInfo != null && imsiEncryptionInfo.getExpirationTime() != null) {
		if (minExpirationDate > imsiEncryptionInfo.getExpirationTime().getTime()) {
		minExpirationDate = imsiEncryptionInfo.getExpirationTime().getTime();
		}
		}
		}

		// if there are no keys, or expiration date is in the past, or within 7 days, then we
		// set the alarm to run in a day. Else, we'll set the alarm to run 7 days prior to
		// expiration.
		if (minExpirationDate == Long.MAX_VALUE \|\| (minExpirationDate
		< System.currentTimeMillis() + DEFAULT_RENEWAL_WINDOW_DAYS * DAY_IN_MILLIS)) {
		minExpirationDate = System.currentTimeMillis() + DAY_IN_MILLIS;
		} else {
		minExpirationDate = minExpirationDate - DEFAULT_RENEWAL_WINDOW_DAYS * DAY_IN_MILLIS;
		}
		Log.d(LOG_TAG, "minExpirationDate: " + new Date(minExpirationDate));
		final AlarmManager alarmManager = (AlarmManager) mContext.getSystemService(
		Context.ALARM_SERVICE);
		Intent intent = new Intent(INTENT_KEY_RENEWAL_ALARM_PREFIX + slotId);
		PendingIntent carrierKeyDownloadIntent = PendingIntent.getBroadcast(mContext, 0, intent,
		PendingIntent.FLAG_UPDATE_CURRENT);
		alarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, minExpirationDate,
		carrierKeyDownloadIntent);
		Log.d(LOG_TAG, "setRenewelAlarm: action=" + intent.getAction() + " time="
		+ new Date(minExpirationDate));
		}

		private String getMccMncSetFromPref() {
		// check if this is a download that we had created. We do this by checking if the
		// downloadId is stored in the shared prefs.
		int slotId = mPhone.getPhoneId();
		SharedPreferences preferences = getDefaultSharedPreferences(mContext);
		return preferences.getString(MCC_MNC_PREF_TAG + slotId, null);
		}

		/**
		* checks if the download was sent by this particular instance. We do this by including the
		* slot id in the key. If no value is found, we know that the download was not for this
		* instance of the phone.
		**/
		private boolean isValidDownload(String mccMnc) {
		String mccCurrent = "";
		String mncCurrent = "";
		String mccSource = "";
		String mncSource = "";
		final TelephonyManager telephonyManager =
		(TelephonyManager) mContext.getSystemService(Context.TELEPHONY_SERVICE);
		String networkOperator = telephonyManager.getNetworkOperator(mPhone.getSubId());

		if (TextUtils.isEmpty(networkOperator) \|\| TextUtils.isEmpty(mccMnc)) {
		Log.e(LOG_TAG, "networkOperator or mcc/mnc is empty");
		return false;
		}

		String[] splitValue = mccMnc.split(SEPARATOR);
		mccSource = splitValue[0];
		mncSource = splitValue[1];
		Log.d(LOG_TAG, "values from sharedPrefs mcc, mnc: " + mccSource + "," + mncSource);

		mccCurrent = networkOperator.substring(0, 3);
		mncCurrent = networkOperator.substring(3);
		Log.d(LOG_TAG, "using values for mcc, mnc: " + mccCurrent + "," + mncCurrent);

		if (TextUtils.equals(mncSource, mncCurrent) && TextUtils.equals(mccSource, mccCurrent)) {
		return true;
		}
		return false;
		}

		/**
		* This method will try to parse the downloaded information, and persist it in the database.
		**/
		private void onDownloadComplete(long carrierKeyDownloadIdentifier, String mccMnc) {
		Log.d(LOG_TAG, "onDownloadComplete: " + carrierKeyDownloadIdentifier);
		String jsonStr;
		DownloadManager.Query query = new DownloadManager.Query();
		query.setFilterById(carrierKeyDownloadIdentifier);
		Cursor cursor = mDownloadManager.query(query);

		if (cursor == null) {
		return;
		}
		if (cursor.moveToFirst()) {
		int columnIndex = cursor.getColumnIndex(DownloadManager.COLUMN_STATUS);
		if (DownloadManager.STATUS_SUCCESSFUL == cursor.getInt(columnIndex)) {
		try {
		final InputStream source = new FileInputStream(
		mDownloadManager.openDownloadedFile(carrierKeyDownloadIdentifier)
		.getFileDescriptor());
		jsonStr = convertToString(source);
		parseJsonAndPersistKey(jsonStr, mccMnc);
		} catch (Exception e) {
		Log.e(LOG_TAG, "Error in download:" + carrierKeyDownloadIdentifier
		+ ". " + e);
		} finally {
		mDownloadManager.remove(carrierKeyDownloadIdentifier);
		}
		}
		Log.d(LOG_TAG, "Completed downloading keys");
		}
		cursor.close();
		return;
		}

		/**
		* This method checks if the carrier requires key. We'll read the carrier config to make that
		* determination.
		* @return boolean returns true if carrier requires keys, else false.
		**/
		private boolean carrierUsesKeys() {
		CarrierConfigManager carrierConfigManager = (CarrierConfigManager)
		mContext.getSystemService(Context.CARRIER_CONFIG_SERVICE);
		if (carrierConfigManager == null) {
		return false;
		}
		int subId = mPhone.getSubId();
		PersistableBundle b = carrierConfigManager.getConfigForSubId(subId);
		if (b == null) {
		return false;
		}
		mKeyAvailability = b.getInt(CarrierConfigManager.IMSI_KEY_AVAILABILITY_INT);
		mURL = b.getString(CarrierConfigManager.IMSI_KEY_DOWNLOAD_URL_STRING);
		if (TextUtils.isEmpty(mURL) \|\| mKeyAvailability == 0) {
		Log.d(LOG_TAG, "Carrier not enabled or invalid values");
		return false;
		}
		for (int key_type : CARRIER_KEY_TYPES) {
		if (isKeyEnabled(key_type)) {
		return true;
		}
		}
		return false;
		}

		private static String convertToString(InputStream is) {
		BufferedReader reader = new BufferedReader(new InputStreamReader(is));
		StringBuilder sb = new StringBuilder();

		String line;
		try {
		while ((line = reader.readLine()) != null) {
		sb.append(line).append('\n');
		}
		} catch (IOException e) {
		e.printStackTrace();
		} finally {
		try {
		is.close();
		} catch (IOException e) {
		e.printStackTrace();
		}
		}
		return sb.toString();
		}

		/**
		* Converts the string into a json object to retreive the nodes. The Json should have 3 nodes,
		* including the Carrier public key, the key type and the key identifier. Once the nodes have
		* been extracted, they get persisted to the database. Sample:
		* "carrier-keys": [ { "key": "",
		* "type": WLAN,
		* "identifier": "",
		* "expiration-date": 1502577746000
		* } ]
		* @param jsonStr the json string.
		* @param mccMnc contains the mcc, mnc
		*/
		private void parseJsonAndPersistKey(String jsonStr, String mccMnc) {
		if (TextUtils.isEmpty(jsonStr) \|\| TextUtils.isEmpty(mccMnc)) {
		Log.e(LOG_TAG, "jsonStr or mcc, mnc: is empty");
		return;
		}
		try {
		String mcc = "";
		String mnc = "";
		String[] splitValue = mccMnc.split(SEPARATOR);
		mcc = splitValue[0];
		mnc = splitValue[1];
		JSONObject jsonObj = new JSONObject(jsonStr);
		JSONArray keys = jsonObj.getJSONArray(JSON_CARRIER_KEYS);

		for (int i = 0; i < keys.length(); i++) {
		JSONObject key = keys.getJSONObject(i);
		String carrierKey = key.getString(JSON_KEY);
		String typeString = key.getString(JSON_TYPE);
		int type = UNINITIALIZED_KEY_TYPE;
		if (typeString.equals(JSON_TYPE_VALUE_WLAN)) {
		type = TelephonyManager.KEY_TYPE_WLAN;
		} else if (typeString.equals(JSON_TYPE_VALUE_EPDG)) {
		type = TelephonyManager.KEY_TYPE_EPDG;
		}
		long expiration_date = key.getLong(JSON_EXPIRATION_DATE);
		String identifier = key.getString(JSON_IDENTIFIER);
		savePublicKey(carrierKey, type, identifier, expiration_date,
		mcc, mnc);
		}
		} catch (final JSONException e) {
		Log.e(LOG_TAG, "Json parsing error: " + e.getMessage());
		}
		}

		/**
		* introspects the mKeyAvailability bitmask
		* @return true if the digit at position k is 1, else false.
		*/

		private boolean isKeyEnabled(int keyType) {
		//since keytype has values of 1, 2.... we need to subtract 1 from the keytype.
		int returnValue = (mKeyAvailability >> (keyType - 1)) & 1;
		return (returnValue == 1) ? true : false;
		}

		/**
		* Checks whether is the keys are absent or close to expiration. Returns true, if either of
		* those conditions are true.
		* @return boolean returns true when keys are absent or close to expiration, else false.
		*/
		@VisibleForTesting
		public boolean areCarrierKeysAbsentOrExpiring() {
		for (int key_type : CARRIER_KEY_TYPES) {
		if (!isKeyEnabled(key_type)) {
		continue;
		}
		ImsiEncryptionInfo imsiEncryptionInfo =
		mPhone.getCarrierInfoForImsiEncryption(key_type);
		if (imsiEncryptionInfo == null) {
		Log.d(LOG_TAG, "Key not found for: " + key_type);
		return true;
		}
		Date imsiDate = imsiEncryptionInfo.getExpirationTime();
		long timeToExpire = imsiDate.getTime() - System.currentTimeMillis();
		return (timeToExpire < DEFAULT_RENEWAL_WINDOW_DAYS * DAY_IN_MILLIS) ? true : false;
		}
		return false;
		}

		private boolean downloadKey() {
		Log.d(LOG_TAG, "starting download from: " + mURL);
		final TelephonyManager telephonyManager =
		(TelephonyManager) mContext.getSystemService(Context.TELEPHONY_SERVICE);
		String mcc = "";
		String mnc = "";
		String networkOperator = telephonyManager.getNetworkOperator(mPhone.getSubId());

		if (!TextUtils.isEmpty(networkOperator)) {
		mcc = networkOperator.substring(0, 3);
		mnc = networkOperator.substring(3);
		Log.d(LOG_TAG, "using values for mcc, mnc: " + mcc + "," + mnc);
		} else {
		Log.e(LOG_TAG, "mcc, mnc: is empty");
		return false;
		}
		try {
		DownloadManager.Request request = new DownloadManager.Request(Uri.parse(mURL));
		request.setAllowedOverMetered(false);
		request.setVisibleInDownloadsUi(false);
		Long carrierKeyDownloadRequestId = mDownloadManager.enqueue(request);
		SharedPreferences.Editor editor = getDefaultSharedPreferences(mContext).edit();

		String mccMnc = mcc + SEPARATOR + mnc;
		int slotId = mPhone.getPhoneId();
		Log.d(LOG_TAG, "storing values in sharedpref mcc, mnc, days: " + mcc + "," + mnc
		+ "," + carrierKeyDownloadRequestId);
		editor.putString(MCC_MNC_PREF_TAG + slotId, mccMnc);
		editor.commit();
		} catch (Exception e) {
		Log.e(LOG_TAG, "exception trying to dowload key from url: " + mURL);
		return false;
		}
		return true;
		}

		private void savePublicKey(String key, int type, String identifier, long expirationDate,
		String mcc, String mnc) {
		byte[] keyBytes = Base64.decode(key.getBytes(), Base64.DEFAULT);
		ImsiEncryptionInfo imsiEncryptionInfo = new ImsiEncryptionInfo(mcc, mnc, type, identifier,
		keyBytes, new Date(expirationDate));
		mPhone.setCarrierInfoForImsiEncryption(imsiEncryptionInfo);
		}
		}

src/java/com/android/internal/telephony/GsmCdmaPhone.java

+2 −1

Original line number	Diff line number	Diff line
		@@ -187,7 +187,7 @@ public class GsmCdmaPhone extends Phone {

		private int mRilVersion;
		private boolean mBroadcastEmergencyCallStateChanges = false;

		private CarrierKeyDownloadManager mCDM;
		// Constructors

		public GsmCdmaPhone(Context context, CommandsInterface ci, PhoneNotifier notifier, int phoneId,
		@@ -269,6 +269,7 @@ public class GsmCdmaPhone extends Phone {
		mCi.registerForVoiceRadioTechChanged(this, EVENT_VOICE_RADIO_TECH_CHANGED, null);
		mContext.registerReceiver(mBroadcastReceiver, new IntentFilter(
		CarrierConfigManager.ACTION_CARRIER_CONFIG_CHANGED));
		mCDM = new CarrierKeyDownloadManager(this);
		}

		private void initRatSpecific(int precisePhoneType) {