1 /* 2 * Copyright (C) 2016 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 #include "KeyStorage.h" 18 19 #include "Keymaster.h" 20 #include "ScryptParameters.h" 21 #include "Utils.h" 22 23 #include <vector> 24 25 #include <errno.h> 26 #include <stdio.h> 27 #include <sys/stat.h> 28 #include <sys/types.h> 29 #include <sys/wait.h> 30 #include <unistd.h> 31 32 #include <openssl/err.h> 33 #include <openssl/evp.h> 34 #include <openssl/sha.h> 35 36 #include <android-base/file.h> 37 #include <android-base/logging.h> 38 #include <android-base/unique_fd.h> 39 40 #include <cutils/properties.h> 41 42 #include <hardware/hw_auth_token.h> 43 #include <keymasterV4_0/authorization_set.h> 44 #include <keymasterV4_0/keymaster_utils.h> 45 46 extern "C" { 47 48 #include "crypto_scrypt.h" 49 } 50 51 namespace android { 52 namespace vold { 53 54 const KeyAuthentication kEmptyAuthentication{"", ""}; 55 56 static constexpr size_t AES_KEY_BYTES = 32; 57 static constexpr size_t GCM_NONCE_BYTES = 12; 58 static constexpr size_t GCM_MAC_BYTES = 16; 59 static constexpr size_t SALT_BYTES = 1 << 4; 60 static constexpr size_t SECDISCARDABLE_BYTES = 1 << 14; 61 static constexpr size_t STRETCHED_BYTES = 1 << 6; 62 63 static constexpr uint32_t AUTH_TIMEOUT = 30; // Seconds 64 65 static const char* kCurrentVersion = "1"; 66 static const char* kRmPath = "/system/bin/rm"; 67 static const char* kSecdiscardPath = "/system/bin/secdiscard"; 68 static const char* kStretch_none = "none"; 69 static const char* kStretch_nopassword = "nopassword"; 70 static const std::string kStretchPrefix_scrypt = "scrypt "; 71 static const char* kHashPrefix_secdiscardable = "Android secdiscardable SHA512"; 72 static const char* kHashPrefix_keygen = "Android key wrapping key generation SHA512"; 73 static const char* kFn_encrypted_key = "encrypted_key"; 74 static const char* kFn_keymaster_key_blob = "keymaster_key_blob"; 75 static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded"; 76 static const char* kFn_salt = "salt"; 77 static const char* kFn_secdiscardable = "secdiscardable"; 78 static const char* kFn_stretching = "stretching"; 79 static const char* kFn_version = "version"; 80 81 static bool checkSize(const std::string& kind, size_t actual, size_t expected) { 82 if (actual != expected) { 83 LOG(ERROR) << "Wrong number of bytes in " << kind << ", expected " << expected << " got " 84 << actual; 85 return false; 86 } 87 return true; 88 } 89 90 static void hashWithPrefix(char const* prefix, const std::string& tohash, std::string* res) { 91 SHA512_CTX c; 92 93 SHA512_Init(&c); 94 // Personalise the hashing by introducing a fixed prefix. 95 // Hashing applications should use personalization except when there is a 96 // specific reason not to; see section 4.11 of https://www.schneier.com/skein1.3.pdf 97 std::string hashingPrefix = prefix; 98 hashingPrefix.resize(SHA512_CBLOCK); 99 SHA512_Update(&c, hashingPrefix.data(), hashingPrefix.size()); 100 SHA512_Update(&c, tohash.data(), tohash.size()); 101 res->assign(SHA512_DIGEST_LENGTH, '\0'); 102 SHA512_Final(reinterpret_cast<uint8_t*>(&(*res)[0]), &c); 103 } 104 105 static bool generateKeymasterKey(Keymaster& keymaster, const KeyAuthentication& auth, 106 const std::string& appId, std::string* key) { 107 auto paramBuilder = km::AuthorizationSetBuilder() 108 .AesEncryptionKey(AES_KEY_BYTES * 8) 109 .GcmModeMinMacLen(GCM_MAC_BYTES * 8) 110 .Authorization(km::TAG_APPLICATION_ID, km::support::blob2hidlVec(appId)); 111 if (auth.token.empty()) { 112 LOG(DEBUG) << "Creating key that doesn't need auth token"; 113 paramBuilder.Authorization(km::TAG_NO_AUTH_REQUIRED); 114 } else { 115 LOG(DEBUG) << "Auth token required for key"; 116 if (auth.token.size() != sizeof(hw_auth_token_t)) { 117 LOG(ERROR) << "Auth token should be " << sizeof(hw_auth_token_t) << " bytes, was " 118 << auth.token.size() << " bytes"; 119 return false; 120 } 121 const hw_auth_token_t* at = reinterpret_cast<const hw_auth_token_t*>(auth.token.data()); 122 paramBuilder.Authorization(km::TAG_USER_SECURE_ID, at->user_id); 123 paramBuilder.Authorization(km::TAG_USER_AUTH_TYPE, km::HardwareAuthenticatorType::PASSWORD); 124 paramBuilder.Authorization(km::TAG_AUTH_TIMEOUT, AUTH_TIMEOUT); 125 } 126 return keymaster.generateKey(paramBuilder, key); 127 } 128 129 static std::pair<km::AuthorizationSet, km::HardwareAuthToken> beginParams( 130 const KeyAuthentication& auth, const std::string& appId) { 131 auto paramBuilder = km::AuthorizationSetBuilder() 132 .GcmModeMacLen(GCM_MAC_BYTES * 8) 133 .Authorization(km::TAG_APPLICATION_ID, km::support::blob2hidlVec(appId)); 134 km::HardwareAuthToken authToken; 135 if (!auth.token.empty()) { 136 LOG(DEBUG) << "Supplying auth token to Keymaster"; 137 authToken = km::support::hidlVec2AuthToken(km::support::blob2hidlVec(auth.token)); 138 } 139 return {paramBuilder, authToken}; 140 } 141 142 static bool readFileToString(const std::string& filename, std::string* result) { 143 if (!android::base::ReadFileToString(filename, result)) { 144 PLOG(ERROR) << "Failed to read from " << filename; 145 return false; 146 } 147 return true; 148 } 149 150 static bool writeStringToFile(const std::string& payload, const std::string& filename) { 151 android::base::unique_fd fd(TEMP_FAILURE_RETRY( 152 open(filename.c_str(), O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC | O_CLOEXEC, 0666))); 153 if (fd == -1) { 154 PLOG(ERROR) << "Failed to open " << filename; 155 return false; 156 } 157 if (!android::base::WriteStringToFd(payload, fd)) { 158 PLOG(ERROR) << "Failed to write to " << filename; 159 unlink(filename.c_str()); 160 return false; 161 } 162 // fsync as close won't guarantee flush data 163 // see close(2), fsync(2) and b/68901441 164 if (fsync(fd) == -1) { 165 if (errno == EROFS || errno == EINVAL) { 166 PLOG(WARNING) << "Skip fsync " << filename 167 << " on a file system does not support synchronization"; 168 } else { 169 PLOG(ERROR) << "Failed to fsync " << filename; 170 unlink(filename.c_str()); 171 return false; 172 } 173 } 174 return true; 175 } 176 177 static bool readRandomBytesOrLog(size_t count, std::string* out) { 178 auto status = ReadRandomBytes(count, *out); 179 if (status != OK) { 180 LOG(ERROR) << "Random read failed with status: " << status; 181 return false; 182 } 183 return true; 184 } 185 186 bool createSecdiscardable(const std::string& filename, std::string* hash) { 187 std::string secdiscardable; 188 if (!readRandomBytesOrLog(SECDISCARDABLE_BYTES, &secdiscardable)) return false; 189 if (!writeStringToFile(secdiscardable, filename)) return false; 190 hashWithPrefix(kHashPrefix_secdiscardable, secdiscardable, hash); 191 return true; 192 } 193 194 bool readSecdiscardable(const std::string& filename, std::string* hash) { 195 std::string secdiscardable; 196 if (!readFileToString(filename, &secdiscardable)) return false; 197 hashWithPrefix(kHashPrefix_secdiscardable, secdiscardable, hash); 198 return true; 199 } 200 201 static KeymasterOperation begin(Keymaster& keymaster, const std::string& dir, 202 km::KeyPurpose purpose, const km::AuthorizationSet& keyParams, 203 const km::AuthorizationSet& opParams, 204 const km::HardwareAuthToken& authToken, 205 km::AuthorizationSet* outParams) { 206 auto kmKeyPath = dir + "/" + kFn_keymaster_key_blob; 207 std::string kmKey; 208 if (!readFileToString(kmKeyPath, &kmKey)) return KeymasterOperation(); 209 km::AuthorizationSet inParams(keyParams); 210 inParams.append(opParams.begin(), opParams.end()); 211 for (;;) { 212 auto opHandle = keymaster.begin(purpose, kmKey, inParams, authToken, outParams); 213 if (opHandle) { 214 return opHandle; 215 } 216 if (opHandle.errorCode() != km::ErrorCode::KEY_REQUIRES_UPGRADE) return opHandle; 217 LOG(DEBUG) << "Upgrading key: " << dir; 218 std::string newKey; 219 if (!keymaster.upgradeKey(kmKey, keyParams, &newKey)) return KeymasterOperation(); 220 auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded; 221 if (!writeStringToFile(newKey, newKeyPath)) return KeymasterOperation(); 222 if (rename(newKeyPath.c_str(), kmKeyPath.c_str()) != 0) { 223 PLOG(ERROR) << "Unable to move upgraded key to location: " << kmKeyPath; 224 return KeymasterOperation(); 225 } 226 if (!keymaster.deleteKey(kmKey)) { 227 LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir; 228 } 229 kmKey = newKey; 230 LOG(INFO) << "Key upgraded: " << dir; 231 } 232 } 233 234 static bool encryptWithKeymasterKey(Keymaster& keymaster, const std::string& dir, 235 const km::AuthorizationSet& keyParams, 236 const km::HardwareAuthToken& authToken, 237 const KeyBuffer& message, std::string* ciphertext) { 238 km::AuthorizationSet opParams; 239 km::AuthorizationSet outParams; 240 auto opHandle = 241 begin(keymaster, dir, km::KeyPurpose::ENCRYPT, keyParams, opParams, authToken, &outParams); 242 if (!opHandle) return false; 243 auto nonceBlob = outParams.GetTagValue(km::TAG_NONCE); 244 if (!nonceBlob.isOk()) { 245 LOG(ERROR) << "GCM encryption but no nonce generated"; 246 return false; 247 } 248 // nonceBlob here is just a pointer into existing data, must not be freed 249 std::string nonce(reinterpret_cast<const char*>(&nonceBlob.value()[0]), 250 nonceBlob.value().size()); 251 if (!checkSize("nonce", nonce.size(), GCM_NONCE_BYTES)) return false; 252 std::string body; 253 if (!opHandle.updateCompletely(message, &body)) return false; 254 255 std::string mac; 256 if (!opHandle.finish(&mac)) return false; 257 if (!checkSize("mac", mac.size(), GCM_MAC_BYTES)) return false; 258 *ciphertext = nonce + body + mac; 259 return true; 260 } 261 262 static bool decryptWithKeymasterKey(Keymaster& keymaster, const std::string& dir, 263 const km::AuthorizationSet& keyParams, 264 const km::HardwareAuthToken& authToken, 265 const std::string& ciphertext, KeyBuffer* message) { 266 auto nonce = ciphertext.substr(0, GCM_NONCE_BYTES); 267 auto bodyAndMac = ciphertext.substr(GCM_NONCE_BYTES); 268 auto opParams = km::AuthorizationSetBuilder().Authorization(km::TAG_NONCE, 269 km::support::blob2hidlVec(nonce)); 270 auto opHandle = 271 begin(keymaster, dir, km::KeyPurpose::DECRYPT, keyParams, opParams, authToken, nullptr); 272 if (!opHandle) return false; 273 if (!opHandle.updateCompletely(bodyAndMac, message)) return false; 274 if (!opHandle.finish(nullptr)) return false; 275 return true; 276 } 277 278 static std::string getStretching(const KeyAuthentication& auth) { 279 if (!auth.usesKeymaster()) { 280 return kStretch_none; 281 } else if (auth.secret.empty()) { 282 return kStretch_nopassword; 283 } else { 284 char paramstr[PROPERTY_VALUE_MAX]; 285 286 property_get(SCRYPT_PROP, paramstr, SCRYPT_DEFAULTS); 287 return std::string() + kStretchPrefix_scrypt + paramstr; 288 } 289 } 290 291 static bool stretchingNeedsSalt(const std::string& stretching) { 292 return stretching != kStretch_nopassword && stretching != kStretch_none; 293 } 294 295 static bool stretchSecret(const std::string& stretching, const std::string& secret, 296 const std::string& salt, std::string* stretched) { 297 if (stretching == kStretch_nopassword) { 298 if (!secret.empty()) { 299 LOG(WARNING) << "Password present but stretching is nopassword"; 300 // Continue anyway 301 } 302 stretched->clear(); 303 } else if (stretching == kStretch_none) { 304 *stretched = secret; 305 } else if (std::equal(kStretchPrefix_scrypt.begin(), kStretchPrefix_scrypt.end(), 306 stretching.begin())) { 307 int Nf, rf, pf; 308 if (!parse_scrypt_parameters(stretching.substr(kStretchPrefix_scrypt.size()).c_str(), &Nf, 309 &rf, &pf)) { 310 LOG(ERROR) << "Unable to parse scrypt params in stretching: " << stretching; 311 return false; 312 } 313 stretched->assign(STRETCHED_BYTES, '\0'); 314 if (crypto_scrypt(reinterpret_cast<const uint8_t*>(secret.data()), secret.size(), 315 reinterpret_cast<const uint8_t*>(salt.data()), salt.size(), 1 << Nf, 316 1 << rf, 1 << pf, reinterpret_cast<uint8_t*>(&(*stretched)[0]), 317 stretched->size()) != 0) { 318 LOG(ERROR) << "scrypt failed with params: " << stretching; 319 return false; 320 } 321 } else { 322 LOG(ERROR) << "Unknown stretching type: " << stretching; 323 return false; 324 } 325 return true; 326 } 327 328 static bool generateAppId(const KeyAuthentication& auth, const std::string& stretching, 329 const std::string& salt, const std::string& secdiscardable_hash, 330 std::string* appId) { 331 std::string stretched; 332 if (!stretchSecret(stretching, auth.secret, salt, &stretched)) return false; 333 *appId = secdiscardable_hash + stretched; 334 return true; 335 } 336 337 static void logOpensslError() { 338 LOG(ERROR) << "Openssl error: " << ERR_get_error(); 339 } 340 341 static bool encryptWithoutKeymaster(const std::string& preKey, const KeyBuffer& plaintext, 342 std::string* ciphertext) { 343 std::string key; 344 hashWithPrefix(kHashPrefix_keygen, preKey, &key); 345 key.resize(AES_KEY_BYTES); 346 if (!readRandomBytesOrLog(GCM_NONCE_BYTES, ciphertext)) return false; 347 auto ctx = std::unique_ptr<EVP_CIPHER_CTX, decltype(&::EVP_CIPHER_CTX_free)>( 348 EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free); 349 if (!ctx) { 350 logOpensslError(); 351 return false; 352 } 353 if (1 != EVP_EncryptInit_ex(ctx.get(), EVP_aes_256_gcm(), NULL, 354 reinterpret_cast<const uint8_t*>(key.data()), 355 reinterpret_cast<const uint8_t*>(ciphertext->data()))) { 356 logOpensslError(); 357 return false; 358 } 359 ciphertext->resize(GCM_NONCE_BYTES + plaintext.size() + GCM_MAC_BYTES); 360 int outlen; 361 if (1 != EVP_EncryptUpdate( 362 ctx.get(), reinterpret_cast<uint8_t*>(&(*ciphertext)[0] + GCM_NONCE_BYTES), 363 &outlen, reinterpret_cast<const uint8_t*>(plaintext.data()), plaintext.size())) { 364 logOpensslError(); 365 return false; 366 } 367 if (outlen != static_cast<int>(plaintext.size())) { 368 LOG(ERROR) << "GCM ciphertext length should be " << plaintext.size() << " was " << outlen; 369 return false; 370 } 371 if (1 != EVP_EncryptFinal_ex( 372 ctx.get(), 373 reinterpret_cast<uint8_t*>(&(*ciphertext)[0] + GCM_NONCE_BYTES + plaintext.size()), 374 &outlen)) { 375 logOpensslError(); 376 return false; 377 } 378 if (outlen != 0) { 379 LOG(ERROR) << "GCM EncryptFinal should be 0, was " << outlen; 380 return false; 381 } 382 if (1 != EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_GET_TAG, GCM_MAC_BYTES, 383 reinterpret_cast<uint8_t*>(&(*ciphertext)[0] + GCM_NONCE_BYTES + 384 plaintext.size()))) { 385 logOpensslError(); 386 return false; 387 } 388 return true; 389 } 390 391 static bool decryptWithoutKeymaster(const std::string& preKey, const std::string& ciphertext, 392 KeyBuffer* plaintext) { 393 if (ciphertext.size() < GCM_NONCE_BYTES + GCM_MAC_BYTES) { 394 LOG(ERROR) << "GCM ciphertext too small: " << ciphertext.size(); 395 return false; 396 } 397 std::string key; 398 hashWithPrefix(kHashPrefix_keygen, preKey, &key); 399 key.resize(AES_KEY_BYTES); 400 auto ctx = std::unique_ptr<EVP_CIPHER_CTX, decltype(&::EVP_CIPHER_CTX_free)>( 401 EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free); 402 if (!ctx) { 403 logOpensslError(); 404 return false; 405 } 406 if (1 != EVP_DecryptInit_ex(ctx.get(), EVP_aes_256_gcm(), NULL, 407 reinterpret_cast<const uint8_t*>(key.data()), 408 reinterpret_cast<const uint8_t*>(ciphertext.data()))) { 409 logOpensslError(); 410 return false; 411 } 412 *plaintext = KeyBuffer(ciphertext.size() - GCM_NONCE_BYTES - GCM_MAC_BYTES); 413 int outlen; 414 if (1 != EVP_DecryptUpdate(ctx.get(), reinterpret_cast<uint8_t*>(&(*plaintext)[0]), &outlen, 415 reinterpret_cast<const uint8_t*>(ciphertext.data() + GCM_NONCE_BYTES), 416 plaintext->size())) { 417 logOpensslError(); 418 return false; 419 } 420 if (outlen != static_cast<int>(plaintext->size())) { 421 LOG(ERROR) << "GCM plaintext length should be " << plaintext->size() << " was " << outlen; 422 return false; 423 } 424 if (1 != EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_SET_TAG, GCM_MAC_BYTES, 425 const_cast<void*>(reinterpret_cast<const void*>( 426 ciphertext.data() + GCM_NONCE_BYTES + plaintext->size())))) { 427 logOpensslError(); 428 return false; 429 } 430 if (1 != EVP_DecryptFinal_ex(ctx.get(), 431 reinterpret_cast<uint8_t*>(&(*plaintext)[0] + plaintext->size()), 432 &outlen)) { 433 logOpensslError(); 434 return false; 435 } 436 if (outlen != 0) { 437 LOG(ERROR) << "GCM EncryptFinal should be 0, was " << outlen; 438 return false; 439 } 440 return true; 441 } 442 443 bool pathExists(const std::string& path) { 444 return access(path.c_str(), F_OK) == 0; 445 } 446 447 bool storeKey(const std::string& dir, const KeyAuthentication& auth, const KeyBuffer& key) { 448 if (TEMP_FAILURE_RETRY(mkdir(dir.c_str(), 0700)) == -1) { 449 PLOG(ERROR) << "key mkdir " << dir; 450 return false; 451 } 452 if (!writeStringToFile(kCurrentVersion, dir + "/" + kFn_version)) return false; 453 std::string secdiscardable_hash; 454 if (!createSecdiscardable(dir + "/" + kFn_secdiscardable, &secdiscardable_hash)) return false; 455 std::string stretching = getStretching(auth); 456 if (!writeStringToFile(stretching, dir + "/" + kFn_stretching)) return false; 457 std::string salt; 458 if (stretchingNeedsSalt(stretching)) { 459 if (ReadRandomBytes(SALT_BYTES, salt) != OK) { 460 LOG(ERROR) << "Random read failed"; 461 return false; 462 } 463 if (!writeStringToFile(salt, dir + "/" + kFn_salt)) return false; 464 } 465 std::string appId; 466 if (!generateAppId(auth, stretching, salt, secdiscardable_hash, &appId)) return false; 467 std::string encryptedKey; 468 if (auth.usesKeymaster()) { 469 Keymaster keymaster; 470 if (!keymaster) return false; 471 std::string kmKey; 472 if (!generateKeymasterKey(keymaster, auth, appId, &kmKey)) return false; 473 if (!writeStringToFile(kmKey, dir + "/" + kFn_keymaster_key_blob)) return false; 474 km::AuthorizationSet keyParams; 475 km::HardwareAuthToken authToken; 476 std::tie(keyParams, authToken) = beginParams(auth, appId); 477 if (!encryptWithKeymasterKey(keymaster, dir, keyParams, authToken, key, &encryptedKey)) 478 return false; 479 } else { 480 if (!encryptWithoutKeymaster(appId, key, &encryptedKey)) return false; 481 } 482 if (!writeStringToFile(encryptedKey, dir + "/" + kFn_encrypted_key)) return false; 483 return true; 484 } 485 486 bool storeKeyAtomically(const std::string& key_path, const std::string& tmp_path, 487 const KeyAuthentication& auth, const KeyBuffer& key) { 488 if (pathExists(key_path)) { 489 LOG(ERROR) << "Already exists, cannot create key at: " << key_path; 490 return false; 491 } 492 if (pathExists(tmp_path)) { 493 LOG(DEBUG) << "Already exists, destroying: " << tmp_path; 494 destroyKey(tmp_path); // May be partially created so ignore errors 495 } 496 if (!storeKey(tmp_path, auth, key)) return false; 497 if (rename(tmp_path.c_str(), key_path.c_str()) != 0) { 498 PLOG(ERROR) << "Unable to move new key to location: " << key_path; 499 return false; 500 } 501 LOG(DEBUG) << "Created key: " << key_path; 502 return true; 503 } 504 505 bool retrieveKey(const std::string& dir, const KeyAuthentication& auth, KeyBuffer* key) { 506 std::string version; 507 if (!readFileToString(dir + "/" + kFn_version, &version)) return false; 508 if (version != kCurrentVersion) { 509 LOG(ERROR) << "Version mismatch, expected " << kCurrentVersion << " got " << version; 510 return false; 511 } 512 std::string secdiscardable_hash; 513 if (!readSecdiscardable(dir + "/" + kFn_secdiscardable, &secdiscardable_hash)) return false; 514 std::string stretching; 515 if (!readFileToString(dir + "/" + kFn_stretching, &stretching)) return false; 516 std::string salt; 517 if (stretchingNeedsSalt(stretching)) { 518 if (!readFileToString(dir + "/" + kFn_salt, &salt)) return false; 519 } 520 std::string appId; 521 if (!generateAppId(auth, stretching, salt, secdiscardable_hash, &appId)) return false; 522 std::string encryptedMessage; 523 if (!readFileToString(dir + "/" + kFn_encrypted_key, &encryptedMessage)) return false; 524 if (auth.usesKeymaster()) { 525 Keymaster keymaster; 526 if (!keymaster) return false; 527 km::AuthorizationSet keyParams; 528 km::HardwareAuthToken authToken; 529 std::tie(keyParams, authToken) = beginParams(auth, appId); 530 if (!decryptWithKeymasterKey(keymaster, dir, keyParams, authToken, encryptedMessage, key)) 531 return false; 532 } else { 533 if (!decryptWithoutKeymaster(appId, encryptedMessage, key)) return false; 534 } 535 return true; 536 } 537 538 static bool deleteKey(const std::string& dir) { 539 std::string kmKey; 540 if (!readFileToString(dir + "/" + kFn_keymaster_key_blob, &kmKey)) return false; 541 Keymaster keymaster; 542 if (!keymaster) return false; 543 if (!keymaster.deleteKey(kmKey)) return false; 544 return true; 545 } 546 547 bool runSecdiscardSingle(const std::string& file) { 548 if (ForkExecvp(std::vector<std::string>{kSecdiscardPath, "--", file}) != 0) { 549 LOG(ERROR) << "secdiscard failed"; 550 return false; 551 } 552 return true; 553 } 554 555 static bool recursiveDeleteKey(const std::string& dir) { 556 if (ForkExecvp(std::vector<std::string>{kRmPath, "-rf", dir}) != 0) { 557 LOG(ERROR) << "recursive delete failed"; 558 return false; 559 } 560 return true; 561 } 562 563 bool destroyKey(const std::string& dir) { 564 bool success = true; 565 // Try each thing, even if previous things failed. 566 bool uses_km = pathExists(dir + "/" + kFn_keymaster_key_blob); 567 if (uses_km) { 568 success &= deleteKey(dir); 569 } 570 auto secdiscard_cmd = std::vector<std::string>{ 571 kSecdiscardPath, "--", dir + "/" + kFn_encrypted_key, dir + "/" + kFn_secdiscardable, 572 }; 573 if (uses_km) { 574 secdiscard_cmd.emplace_back(dir + "/" + kFn_keymaster_key_blob); 575 } 576 if (ForkExecvp(secdiscard_cmd) != 0) { 577 LOG(ERROR) << "secdiscard failed"; 578 success = false; 579 } 580 success &= recursiveDeleteKey(dir); 581 return success; 582 } 583 584 } // namespace vold 585 } // namespace android 586
