RecoverySystem.java revision e2d58e95a09590a63f1c597bb808b925bcab9a69
1/* 2 * Copyright (C) 2010 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 17package android.os; 18 19import android.content.BroadcastReceiver; 20import android.content.Context; 21import android.content.Intent; 22import android.util.Log; 23 24import java.io.ByteArrayInputStream; 25import java.io.File; 26import java.io.FileNotFoundException; 27import java.io.FileWriter; 28import java.io.IOException; 29import java.io.InputStream; 30import java.io.RandomAccessFile; 31import java.security.GeneralSecurityException; 32import java.security.PublicKey; 33import java.security.Signature; 34import java.security.SignatureException; 35import java.security.cert.Certificate; 36import java.security.cert.CertificateFactory; 37import java.security.cert.X509Certificate; 38import java.util.Collection; 39import java.util.Enumeration; 40import java.util.HashSet; 41import java.util.Iterator; 42import java.util.List; 43import java.util.zip.ZipEntry; 44import java.util.zip.ZipFile; 45 46import org.apache.harmony.security.asn1.BerInputStream; 47import org.apache.harmony.security.pkcs7.ContentInfo; 48import org.apache.harmony.security.pkcs7.SignedData; 49import org.apache.harmony.security.pkcs7.SignerInfo; 50import org.apache.harmony.security.provider.cert.X509CertImpl; 51 52/** 53 * RecoverySystem contains methods for interacting with the Android 54 * recovery system (the separate partition that can be used to install 55 * system updates, wipe user data, etc.) 56 */ 57public class RecoverySystem { 58 private static final String TAG = "RecoverySystem"; 59 60 /** 61 * Default location of zip file containing public keys (X509 62 * certs) authorized to sign OTA updates. 63 */ 64 private static final File DEFAULT_KEYSTORE = 65 new File("/system/etc/security/otacerts.zip"); 66 67 /** Send progress to listeners no more often than this (in ms). */ 68 private static final long PUBLISH_PROGRESS_INTERVAL_MS = 500; 69 70 /** Used to communicate with recovery. See bootable/recovery/recovery.c. */ 71 private static File RECOVERY_DIR = new File("/cache/recovery"); 72 private static File COMMAND_FILE = new File(RECOVERY_DIR, "command"); 73 private static File LOG_FILE = new File(RECOVERY_DIR, "log"); 74 private static String LAST_PREFIX = "last_"; 75 76 // Length limits for reading files. 77 private static int LOG_FILE_MAX_LENGTH = 64 * 1024; 78 79 /** 80 * Interface definition for a callback to be invoked regularly as 81 * verification proceeds. 82 */ 83 public interface ProgressListener { 84 /** 85 * Called periodically as the verification progresses. 86 * 87 * @param progress the approximate percentage of the 88 * verification that has been completed, ranging from 0 89 * to 100 (inclusive). 90 */ 91 public void onProgress(int progress); 92 } 93 94 /** @return the set of certs that can be used to sign an OTA package. */ 95 private static HashSet<Certificate> getTrustedCerts(File keystore) 96 throws IOException, GeneralSecurityException { 97 HashSet<Certificate> trusted = new HashSet<Certificate>(); 98 if (keystore == null) { 99 keystore = DEFAULT_KEYSTORE; 100 } 101 ZipFile zip = new ZipFile(keystore); 102 try { 103 CertificateFactory cf = CertificateFactory.getInstance("X.509"); 104 Enumeration<? extends ZipEntry> entries = zip.entries(); 105 while (entries.hasMoreElements()) { 106 ZipEntry entry = entries.nextElement(); 107 InputStream is = zip.getInputStream(entry); 108 try { 109 trusted.add(cf.generateCertificate(is)); 110 } finally { 111 is.close(); 112 } 113 } 114 } finally { 115 zip.close(); 116 } 117 return trusted; 118 } 119 120 /** 121 * Verify the cryptographic signature of a system update package 122 * before installing it. Note that the package is also verified 123 * separately by the installer once the device is rebooted into 124 * the recovery system. This function will return only if the 125 * package was successfully verified; otherwise it will throw an 126 * exception. 127 * 128 * Verification of a package can take significant time, so this 129 * function should not be called from a UI thread. Interrupting 130 * the thread while this function is in progress will result in a 131 * SecurityException being thrown (and the thread's interrupt flag 132 * will be cleared). 133 * 134 * @param packageFile the package to be verified 135 * @param listener an object to receive periodic progress 136 * updates as verification proceeds. May be null. 137 * @param deviceCertsZipFile the zip file of certificates whose 138 * public keys we will accept. Verification succeeds if the 139 * package is signed by the private key corresponding to any 140 * public key in this file. May be null to use the system default 141 * file (currently "/system/etc/security/otacerts.zip"). 142 * 143 * @throws IOException if there were any errors reading the 144 * package or certs files. 145 * @throws GeneralSecurityException if verification failed 146 */ 147 public static void verifyPackage(File packageFile, 148 ProgressListener listener, 149 File deviceCertsZipFile) 150 throws IOException, GeneralSecurityException { 151 long fileLen = packageFile.length(); 152 153 RandomAccessFile raf = new RandomAccessFile(packageFile, "r"); 154 try { 155 int lastPercent = 0; 156 long lastPublishTime = System.currentTimeMillis(); 157 if (listener != null) { 158 listener.onProgress(lastPercent); 159 } 160 161 raf.seek(fileLen - 6); 162 byte[] footer = new byte[6]; 163 raf.readFully(footer); 164 165 if (footer[2] != (byte)0xff || footer[3] != (byte)0xff) { 166 throw new SignatureException("no signature in file (no footer)"); 167 } 168 169 int commentSize = (footer[4] & 0xff) | ((footer[5] & 0xff) << 8); 170 int signatureStart = (footer[0] & 0xff) | ((footer[1] & 0xff) << 8); 171 172 byte[] eocd = new byte[commentSize + 22]; 173 raf.seek(fileLen - (commentSize + 22)); 174 raf.readFully(eocd); 175 176 // Check that we have found the start of the 177 // end-of-central-directory record. 178 if (eocd[0] != (byte)0x50 || eocd[1] != (byte)0x4b || 179 eocd[2] != (byte)0x05 || eocd[3] != (byte)0x06) { 180 throw new SignatureException("no signature in file (bad footer)"); 181 } 182 183 for (int i = 4; i < eocd.length-3; ++i) { 184 if (eocd[i ] == (byte)0x50 && eocd[i+1] == (byte)0x4b && 185 eocd[i+2] == (byte)0x05 && eocd[i+3] == (byte)0x06) { 186 throw new SignatureException("EOCD marker found after start of EOCD"); 187 } 188 } 189 190 // The following code is largely copied from 191 // JarUtils.verifySignature(). We could just *call* that 192 // method here if that function didn't read the entire 193 // input (ie, the whole OTA package) into memory just to 194 // compute its message digest. 195 196 BerInputStream bis = new BerInputStream( 197 new ByteArrayInputStream(eocd, commentSize+22-signatureStart, signatureStart)); 198 ContentInfo info = (ContentInfo)ContentInfo.ASN1.decode(bis); 199 SignedData signedData = info.getSignedData(); 200 if (signedData == null) { 201 throw new IOException("signedData is null"); 202 } 203 Collection encCerts = signedData.getCertificates(); 204 if (encCerts.isEmpty()) { 205 throw new IOException("encCerts is empty"); 206 } 207 // Take the first certificate from the signature (packages 208 // should contain only one). 209 Iterator it = encCerts.iterator(); 210 X509Certificate cert = null; 211 if (it.hasNext()) { 212 cert = new X509CertImpl((org.apache.harmony.security.x509.Certificate)it.next()); 213 } else { 214 throw new SignatureException("signature contains no certificates"); 215 } 216 217 List sigInfos = signedData.getSignerInfos(); 218 SignerInfo sigInfo; 219 if (!sigInfos.isEmpty()) { 220 sigInfo = (SignerInfo)sigInfos.get(0); 221 } else { 222 throw new IOException("no signer infos!"); 223 } 224 225 // Check that the public key of the certificate contained 226 // in the package equals one of our trusted public keys. 227 228 HashSet<Certificate> trusted = getTrustedCerts( 229 deviceCertsZipFile == null ? DEFAULT_KEYSTORE : deviceCertsZipFile); 230 231 PublicKey signatureKey = cert.getPublicKey(); 232 boolean verified = false; 233 for (Certificate c : trusted) { 234 if (c.getPublicKey().equals(signatureKey)) { 235 verified = true; 236 break; 237 } 238 } 239 if (!verified) { 240 throw new SignatureException("signature doesn't match any trusted key"); 241 } 242 243 // The signature cert matches a trusted key. Now verify that 244 // the digest in the cert matches the actual file data. 245 246 // The verifier in recovery *only* handles SHA1withRSA 247 // signatures. SignApk.java always uses SHA1withRSA, no 248 // matter what the cert says to use. Ignore 249 // cert.getSigAlgName(), and instead use whatever 250 // algorithm is used by the signature (which should be 251 // SHA1withRSA). 252 253 String da = sigInfo.getDigestAlgorithm(); 254 String dea = sigInfo.getDigestEncryptionAlgorithm(); 255 String alg = null; 256 if (da == null || dea == null) { 257 // fall back to the cert algorithm if the sig one 258 // doesn't look right. 259 alg = cert.getSigAlgName(); 260 } else { 261 alg = da + "with" + dea; 262 } 263 Signature sig = Signature.getInstance(alg); 264 sig.initVerify(cert); 265 266 // The signature covers all of the OTA package except the 267 // archive comment and its 2-byte length. 268 long toRead = fileLen - commentSize - 2; 269 long soFar = 0; 270 raf.seek(0); 271 byte[] buffer = new byte[4096]; 272 boolean interrupted = false; 273 while (soFar < toRead) { 274 interrupted = Thread.interrupted(); 275 if (interrupted) break; 276 int size = buffer.length; 277 if (soFar + size > toRead) { 278 size = (int)(toRead - soFar); 279 } 280 int read = raf.read(buffer, 0, size); 281 sig.update(buffer, 0, read); 282 soFar += read; 283 284 if (listener != null) { 285 long now = System.currentTimeMillis(); 286 int p = (int)(soFar * 100 / toRead); 287 if (p > lastPercent && 288 now - lastPublishTime > PUBLISH_PROGRESS_INTERVAL_MS) { 289 lastPercent = p; 290 lastPublishTime = now; 291 listener.onProgress(lastPercent); 292 } 293 } 294 } 295 if (listener != null) { 296 listener.onProgress(100); 297 } 298 299 if (interrupted) { 300 throw new SignatureException("verification was interrupted"); 301 } 302 303 if (!sig.verify(sigInfo.getEncryptedDigest())) { 304 throw new SignatureException("signature digest verification failed"); 305 } 306 } finally { 307 raf.close(); 308 } 309 } 310 311 /** 312 * Reboots the device in order to install the given update 313 * package. 314 * Requires the {@link android.Manifest.permission#REBOOT} permission. 315 * 316 * @param context the Context to use 317 * @param packageFile the update package to install. Must be on 318 * a partition mountable by recovery. (The set of partitions 319 * known to recovery may vary from device to device. Generally, 320 * /cache and /data are safe.) 321 * 322 * @throws IOException if writing the recovery command file 323 * fails, or if the reboot itself fails. 324 */ 325 public static void installPackage(Context context, File packageFile) 326 throws IOException { 327 String filename = packageFile.getCanonicalPath(); 328 Log.w(TAG, "!!! REBOOTING TO INSTALL " + filename + " !!!"); 329 String arg = "--update_package=" + filename; 330 bootCommand(context, arg); 331 } 332 333 /** 334 * Reboots the device and wipes the user data partition. This is 335 * sometimes called a "factory reset", which is something of a 336 * misnomer because the system partition is not restored to its 337 * factory state. 338 * Requires the {@link android.Manifest.permission#REBOOT} permission. 339 * 340 * @param context the Context to use 341 * 342 * @throws IOException if writing the recovery command file 343 * fails, or if the reboot itself fails. 344 */ 345 public static void rebootWipeUserData(Context context) throws IOException { 346 final ConditionVariable condition = new ConditionVariable(); 347 348 Intent intent = new Intent("android.intent.action.MASTER_CLEAR_NOTIFICATION"); 349 context.sendOrderedBroadcast(intent, android.Manifest.permission.MASTER_CLEAR, 350 new BroadcastReceiver() { 351 @Override 352 public void onReceive(Context context, Intent intent) { 353 condition.open(); 354 } 355 }, null, 0, null, null); 356 357 // Block until the ordered broadcast has completed. 358 condition.block(); 359 360 bootCommand(context, "--wipe_data"); 361 } 362 363 /** 364 * Reboot into the recovery system to wipe the /cache partition. 365 * @throws IOException if something goes wrong. 366 */ 367 public static void rebootWipeCache(Context context) throws IOException { 368 bootCommand(context, "--wipe_cache"); 369 } 370 371 /** 372 * Reboot into the recovery system with the supplied argument. 373 * @param arg to pass to the recovery utility. 374 * @throws IOException if something goes wrong. 375 */ 376 private static void bootCommand(Context context, String arg) throws IOException { 377 RECOVERY_DIR.mkdirs(); // In case we need it 378 COMMAND_FILE.delete(); // In case it's not writable 379 LOG_FILE.delete(); 380 381 FileWriter command = new FileWriter(COMMAND_FILE); 382 try { 383 command.write(arg); 384 command.write("\n"); 385 } finally { 386 command.close(); 387 } 388 389 // Having written the command file, go ahead and reboot 390 PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE); 391 pm.reboot("recovery"); 392 393 throw new IOException("Reboot failed (no permissions?)"); 394 } 395 396 /** 397 * Called after booting to process and remove recovery-related files. 398 * @return the log file from recovery, or null if none was found. 399 * 400 * @hide 401 */ 402 public static String handleAftermath() { 403 // Record the tail of the LOG_FILE 404 String log = null; 405 try { 406 log = FileUtils.readTextFile(LOG_FILE, -LOG_FILE_MAX_LENGTH, "...\n"); 407 } catch (FileNotFoundException e) { 408 Log.i(TAG, "No recovery log file"); 409 } catch (IOException e) { 410 Log.e(TAG, "Error reading recovery log", e); 411 } 412 413 // Delete everything in RECOVERY_DIR except those beginning 414 // with LAST_PREFIX 415 String[] names = RECOVERY_DIR.list(); 416 for (int i = 0; names != null && i < names.length; i++) { 417 if (names[i].startsWith(LAST_PREFIX)) continue; 418 File f = new File(RECOVERY_DIR, names[i]); 419 if (!f.delete()) { 420 Log.e(TAG, "Can't delete: " + f); 421 } else { 422 Log.i(TAG, "Deleted: " + f); 423 } 424 } 425 426 return log; 427 } 428 429 private void RecoverySystem() { } // Do not instantiate 430} 431