Jordan Liu | 26e820c | 2019-10-22 14:42:07 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2019 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.cellbroadcastservice; |
| 18 | |
| 19 | import android.app.AppOpsManager; |
| 20 | import android.content.ContentProvider; |
| 21 | import android.content.ContentUris; |
| 22 | import android.content.ContentValues; |
| 23 | import android.content.Context; |
| 24 | import android.content.UriMatcher; |
| 25 | import android.content.pm.PackageManager; |
| 26 | import android.database.Cursor; |
| 27 | import android.database.sqlite.SQLiteDatabase; |
| 28 | import android.database.sqlite.SQLiteOpenHelper; |
| 29 | import android.database.sqlite.SQLiteQueryBuilder; |
| 30 | import android.net.Uri; |
| 31 | import android.os.Binder; |
| 32 | import android.os.Process; |
| 33 | import android.provider.Telephony.CellBroadcasts; |
| 34 | import android.text.TextUtils; |
| 35 | import android.util.Log; |
| 36 | |
| 37 | import com.android.internal.annotations.VisibleForTesting; |
| 38 | |
| 39 | import java.util.Arrays; |
| 40 | |
| 41 | /** |
| 42 | * The content provider that provides access of cell broadcast message to application. |
| 43 | * Permission {@link android.permission.READ_CELL_BROADCASTS} is required for querying the cell |
| 44 | * broadcast message. Only phone process has the permission to write/update the database via this |
| 45 | * provider. |
| 46 | */ |
| 47 | public class CellBroadcastProvider extends ContentProvider { |
| 48 | /** Interface for read/write permission check. */ |
| 49 | public interface PermissionChecker { |
| 50 | /** Return {@code True} if the caller has the permission to write/update the database. */ |
| 51 | boolean hasWritePermission(); |
| 52 | |
| 53 | /** Return {@code True} if the caller has the permission to query the complete database. */ |
| 54 | boolean hasReadPermission(); |
| 55 | |
| 56 | /** |
| 57 | * Return {@code True} if the caller has the permission to query the database for |
| 58 | * cell broadcast message history. |
| 59 | */ |
| 60 | boolean hasReadPermissionForHistory(); |
| 61 | } |
| 62 | |
| 63 | private static final String TAG = CellBroadcastProvider.class.getSimpleName(); |
| 64 | |
| 65 | private static final boolean DBG = Log.isLoggable(TAG, Log.DEBUG); |
| 66 | |
| 67 | /** Database name. */ |
| 68 | private static final String DATABASE_NAME = "cellbroadcasts.db"; |
| 69 | |
| 70 | /** Database version. */ |
| 71 | private static final int DATABASE_VERSION = 2; |
| 72 | |
| 73 | /** URI matcher for ContentProvider queries. */ |
| 74 | private static final UriMatcher sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH); |
| 75 | |
| 76 | /** URI matcher type to get all cell broadcasts. */ |
| 77 | private static final int ALL = 0; |
| 78 | |
| 79 | /** |
| 80 | * URI matcher type for get all message history, this is used primarily for default |
| 81 | * cellbroadcast app or messaging app to display message history. some information is not |
| 82 | * exposed for messaging history, e.g, messages which are out of broadcast geometrics will not |
| 83 | * be delivered to end users thus will not be returned as message history query result. |
| 84 | */ |
| 85 | private static final int MESSAGE_HISTORY = 1; |
| 86 | |
| 87 | /** MIME type for the list of all cell broadcasts. */ |
| 88 | private static final String LIST_TYPE = "vnd.android.cursor.dir/cellbroadcast"; |
| 89 | |
| 90 | /** Table name of cell broadcast message. */ |
| 91 | @VisibleForTesting |
| 92 | public static final String CELL_BROADCASTS_TABLE_NAME = "cell_broadcasts"; |
| 93 | |
| 94 | /** Authority string for content URIs. */ |
| 95 | @VisibleForTesting |
| 96 | public static final String AUTHORITY = "cellbroadcasts"; |
| 97 | |
| 98 | /** Content uri of this provider. */ |
| 99 | public static final Uri CONTENT_URI = Uri.parse("content://cellbroadcasts"); |
| 100 | |
| 101 | @VisibleForTesting |
| 102 | public PermissionChecker mPermissionChecker; |
| 103 | |
| 104 | /** The database helper for this content provider. */ |
| 105 | @VisibleForTesting |
| 106 | public SQLiteOpenHelper mDbHelper; |
| 107 | |
| 108 | static { |
| 109 | sUriMatcher.addURI(AUTHORITY, null, ALL); |
| 110 | sUriMatcher.addURI(AUTHORITY, "history", MESSAGE_HISTORY); |
| 111 | } |
| 112 | |
| 113 | public CellBroadcastProvider() {} |
| 114 | |
| 115 | @VisibleForTesting |
| 116 | public CellBroadcastProvider(PermissionChecker permissionChecker) { |
| 117 | mPermissionChecker = permissionChecker; |
| 118 | } |
| 119 | |
| 120 | @Override |
| 121 | public boolean onCreate() { |
| 122 | mDbHelper = new CellBroadcastDatabaseHelper(getContext()); |
| 123 | mPermissionChecker = new CellBroadcastPermissionChecker(); |
| 124 | setAppOps(AppOpsManager.OP_READ_CELL_BROADCASTS, AppOpsManager.OP_NONE); |
| 125 | return true; |
| 126 | } |
| 127 | |
| 128 | /** |
| 129 | * Return the MIME type of the data at the specified URI. |
| 130 | * |
| 131 | * @param uri the URI to query. |
| 132 | * @return a MIME type string, or null if there is no type. |
| 133 | */ |
| 134 | @Override |
| 135 | public String getType(Uri uri) { |
| 136 | int match = sUriMatcher.match(uri); |
| 137 | switch (match) { |
| 138 | case ALL: |
| 139 | return LIST_TYPE; |
| 140 | default: |
| 141 | return null; |
| 142 | } |
| 143 | } |
| 144 | |
| 145 | @Override |
| 146 | public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, |
| 147 | String sortOrder) { |
| 148 | checkReadPermission(uri); |
| 149 | |
| 150 | if (DBG) { |
| 151 | Log.d(TAG, "query:" |
| 152 | + " uri = " + uri |
| 153 | + " projection = " + Arrays.toString(projection) |
| 154 | + " selection = " + selection |
| 155 | + " selectionArgs = " + Arrays.toString(selectionArgs) |
| 156 | + " sortOrder = " + sortOrder); |
| 157 | } |
| 158 | SQLiteQueryBuilder qb = new SQLiteQueryBuilder(); |
| 159 | qb.setStrict(true); // a little protection from injection attacks |
| 160 | qb.setTables(CELL_BROADCASTS_TABLE_NAME); |
| 161 | |
| 162 | String orderBy; |
| 163 | if (!TextUtils.isEmpty(sortOrder)) { |
| 164 | orderBy = sortOrder; |
| 165 | } else { |
| 166 | orderBy = CellBroadcasts.RECEIVED_TIME + " DESC"; |
| 167 | } |
| 168 | |
| 169 | int match = sUriMatcher.match(uri); |
| 170 | switch (match) { |
| 171 | case ALL: |
| 172 | return getReadableDatabase().query( |
| 173 | CELL_BROADCASTS_TABLE_NAME, projection, selection, selectionArgs, |
| 174 | null /* groupBy */, null /* having */, orderBy); |
| 175 | case MESSAGE_HISTORY: |
| 176 | // limit projections to certain columns. limit result to broadcasted messages only. |
| 177 | qb.appendWhere(CellBroadcasts.MESSAGE_BROADCASTED + "=1"); |
| 178 | return qb.query(getReadableDatabase(), projection, selection, selectionArgs, null, |
| 179 | null, orderBy); |
| 180 | default: |
| 181 | throw new IllegalArgumentException( |
| 182 | "Query method doesn't support this uri = " + uri); |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | @Override |
| 187 | public Uri insert(Uri uri, ContentValues values) { |
| 188 | checkWritePermission(); |
| 189 | |
| 190 | if (DBG) { |
| 191 | Log.d(TAG, "insert:" |
| 192 | + " uri = " + uri |
| 193 | + " contentValue = " + values); |
| 194 | } |
| 195 | |
| 196 | switch (sUriMatcher.match(uri)) { |
| 197 | case ALL: |
| 198 | long row = getWritableDatabase().insertOrThrow(CELL_BROADCASTS_TABLE_NAME, null, |
| 199 | values); |
| 200 | if (row > 0) { |
| 201 | Uri newUri = ContentUris.withAppendedId(CONTENT_URI, row); |
| 202 | getContext().getContentResolver() |
| 203 | .notifyChange(CONTENT_URI, null /* observer */); |
| 204 | return newUri; |
| 205 | } else { |
| 206 | Log.e(TAG, "Insert record failed because of unknown reason, uri = " + uri); |
| 207 | return null; |
| 208 | } |
| 209 | default: |
| 210 | throw new IllegalArgumentException( |
| 211 | "Insert method doesn't support this uri = " + uri); |
| 212 | } |
| 213 | } |
| 214 | |
| 215 | @Override |
| 216 | public int delete(Uri uri, String selection, String[] selectionArgs) { |
| 217 | checkWritePermission(); |
| 218 | |
| 219 | if (DBG) { |
| 220 | Log.d(TAG, "delete:" |
| 221 | + " uri = " + uri |
| 222 | + " selection = " + selection |
| 223 | + " selectionArgs = " + Arrays.toString(selectionArgs)); |
| 224 | } |
| 225 | |
| 226 | switch (sUriMatcher.match(uri)) { |
| 227 | case ALL: |
| 228 | return getWritableDatabase().delete(CELL_BROADCASTS_TABLE_NAME, |
| 229 | selection, selectionArgs); |
| 230 | default: |
| 231 | throw new IllegalArgumentException( |
| 232 | "Delete method doesn't support this uri = " + uri); |
| 233 | } |
| 234 | } |
| 235 | |
| 236 | @Override |
| 237 | public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { |
| 238 | checkWritePermission(); |
| 239 | |
| 240 | if (DBG) { |
| 241 | Log.d(TAG, "update:" |
| 242 | + " uri = " + uri |
| 243 | + " values = {" + values + "}" |
| 244 | + " selection = " + selection |
| 245 | + " selectionArgs = " + Arrays.toString(selectionArgs)); |
| 246 | } |
| 247 | |
| 248 | switch (sUriMatcher.match(uri)) { |
| 249 | case ALL: |
| 250 | int rowCount = getWritableDatabase().update( |
| 251 | CELL_BROADCASTS_TABLE_NAME, |
| 252 | values, |
| 253 | selection, |
| 254 | selectionArgs); |
| 255 | if (rowCount > 0) { |
| 256 | getContext().getContentResolver().notifyChange(uri, null /* observer */); |
| 257 | } |
| 258 | return rowCount; |
| 259 | default: |
| 260 | throw new IllegalArgumentException( |
| 261 | "Update method doesn't support this uri = " + uri); |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | /** |
| 266 | * Returns a string used to create the cell broadcast table. This is exposed so the unit test |
| 267 | * can construct its own in-memory database to match the cell broadcast db. |
| 268 | */ |
| 269 | @VisibleForTesting |
| 270 | public static String getStringForCellBroadcastTableCreation(String tableName) { |
| 271 | return "CREATE TABLE " + tableName + " (" |
| 272 | + CellBroadcasts._ID + " INTEGER PRIMARY KEY AUTOINCREMENT," |
| 273 | + CellBroadcasts.SUB_ID + " INTEGER," |
| 274 | + CellBroadcasts.SLOT_INDEX + " INTEGER DEFAULT 0," |
| 275 | + CellBroadcasts.GEOGRAPHICAL_SCOPE + " INTEGER," |
| 276 | + CellBroadcasts.PLMN + " TEXT," |
| 277 | + CellBroadcasts.LAC + " INTEGER," |
| 278 | + CellBroadcasts.CID + " INTEGER," |
| 279 | + CellBroadcasts.SERIAL_NUMBER + " INTEGER," |
| 280 | + CellBroadcasts.SERVICE_CATEGORY + " INTEGER," |
| 281 | + CellBroadcasts.LANGUAGE_CODE + " TEXT," |
| 282 | + CellBroadcasts.MESSAGE_BODY + " TEXT," |
| 283 | + CellBroadcasts.MESSAGE_FORMAT + " INTEGER," |
| 284 | + CellBroadcasts.MESSAGE_PRIORITY + " INTEGER," |
| 285 | + CellBroadcasts.ETWS_WARNING_TYPE + " INTEGER," |
| 286 | + CellBroadcasts.CMAS_MESSAGE_CLASS + " INTEGER," |
| 287 | + CellBroadcasts.CMAS_CATEGORY + " INTEGER," |
| 288 | + CellBroadcasts.CMAS_RESPONSE_TYPE + " INTEGER," |
| 289 | + CellBroadcasts.CMAS_SEVERITY + " INTEGER," |
| 290 | + CellBroadcasts.CMAS_URGENCY + " INTEGER," |
| 291 | + CellBroadcasts.CMAS_CERTAINTY + " INTEGER," |
| 292 | + CellBroadcasts.RECEIVED_TIME + " BIGINT," |
| 293 | + CellBroadcasts.MESSAGE_BROADCASTED + " BOOLEAN DEFAULT 0," |
| 294 | + CellBroadcasts.GEOMETRIES + " TEXT," |
| 295 | + CellBroadcasts.MAXIMUM_WAIT_TIME + " INTEGER);"; |
| 296 | } |
| 297 | |
| 298 | private SQLiteDatabase getWritableDatabase() { |
| 299 | return mDbHelper.getWritableDatabase(); |
| 300 | } |
| 301 | |
| 302 | private SQLiteDatabase getReadableDatabase() { |
| 303 | return mDbHelper.getReadableDatabase(); |
| 304 | } |
| 305 | |
| 306 | private void checkWritePermission() { |
| 307 | if (!mPermissionChecker.hasWritePermission()) { |
| 308 | throw new SecurityException( |
| 309 | "No permission to write CellBroadcast provider"); |
| 310 | } |
| 311 | } |
| 312 | |
| 313 | private void checkReadPermission(Uri uri) { |
| 314 | int match = sUriMatcher.match(uri); |
| 315 | switch (match) { |
| 316 | case ALL: |
| 317 | if (!mPermissionChecker.hasReadPermission()) { |
| 318 | throw new SecurityException( |
| 319 | "No permission to read CellBroadcast provider"); |
| 320 | } |
| 321 | break; |
| 322 | case MESSAGE_HISTORY: |
| 323 | // TODO: if we plan to allow apps to query db in framework, we should migrate data |
| 324 | // first before deprecating app's database. otherwise users will lose all history. |
| 325 | if (!mPermissionChecker.hasReadPermissionForHistory()) { |
| 326 | throw new SecurityException( |
| 327 | "No permission to read CellBroadcast provider for message history"); |
| 328 | } |
| 329 | break; |
| 330 | default: |
| 331 | return; |
| 332 | } |
| 333 | } |
| 334 | |
| 335 | private class CellBroadcastDatabaseHelper extends SQLiteOpenHelper { |
| 336 | CellBroadcastDatabaseHelper(Context context) { |
| 337 | super(context, DATABASE_NAME, null /* factory */, DATABASE_VERSION); |
| 338 | } |
| 339 | |
| 340 | @Override |
| 341 | public void onCreate(SQLiteDatabase db) { |
| 342 | db.execSQL(getStringForCellBroadcastTableCreation(CELL_BROADCASTS_TABLE_NAME)); |
| 343 | } |
| 344 | |
| 345 | @Override |
| 346 | public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { |
| 347 | if (DBG) { |
| 348 | Log.d(TAG, "onUpgrade: oldV=" + oldVersion + " newV=" + newVersion); |
| 349 | } |
| 350 | if (newVersion == 2) { |
| 351 | db.execSQL("ALTER TABLE " + CELL_BROADCASTS_TABLE_NAME + " ADD COLUMN " |
| 352 | + CellBroadcasts.SLOT_INDEX + " INTEGER DEFAULT 0;"); |
| 353 | Log.d(TAG, "add slotIndex column"); |
| 354 | } |
| 355 | } |
| 356 | } |
| 357 | |
| 358 | private class CellBroadcastPermissionChecker implements PermissionChecker { |
| 359 | @Override |
| 360 | public boolean hasWritePermission() { |
| 361 | // Only the phone and network statck process has the write permission to modify this |
| 362 | // provider. |
| 363 | return Binder.getCallingUid() == Process.PHONE_UID |
| 364 | || Binder.getCallingUid() == Process.NETWORK_STACK_UID; |
| 365 | } |
| 366 | |
| 367 | @Override |
| 368 | public boolean hasReadPermission() { |
| 369 | // Only the phone and network stack process has the read permission to query data from |
| 370 | // this provider. |
| 371 | return Binder.getCallingUid() == Process.PHONE_UID |
| 372 | || Binder.getCallingUid() == Process.NETWORK_STACK_UID; |
| 373 | } |
| 374 | |
| 375 | @Override |
| 376 | public boolean hasReadPermissionForHistory() { |
| 377 | int status = getContext().checkCallingOrSelfPermission( |
| 378 | "android.permission.RECEIVE_EMERGENCY_BROADCAST"); |
| 379 | if (status == PackageManager.PERMISSION_GRANTED) { |
| 380 | return true; |
| 381 | } |
| 382 | return false; |
| 383 | } |
| 384 | } |
| 385 | } |