crypto/block-luks.c

   1 /*
   2  * QEMU Crypto block device encryption LUKS format
   3  *
   4  * Copyright (c) 2015-2016 Red Hat, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "qapi/error.h"
  23 #include "qemu/bswap.h"
  24
  25 #include "block-luks.h"
  26
  27 #include "crypto/hash.h"
  28 #include "crypto/afsplit.h"
  29 #include "crypto/pbkdf.h"
  30 #include "crypto/secret.h"
  31 #include "crypto/random.h"
  32 #include "qemu/uuid.h"
  33
  34 #include "qemu/coroutine.h"
  35
  36 /*
  37  * Reference for the LUKS format implemented here is
  38  *
  39  *   docs/on-disk-format.pdf
  40  *
  41  * in 'cryptsetup' package source code
  42  *
  43  * This file implements the 1.2.1 specification, dated
  44  * Oct 16, 2011.
  45  */
  46
  47 typedef struct QCryptoBlockLUKS QCryptoBlockLUKS;
  48 typedef struct QCryptoBlockLUKSHeader QCryptoBlockLUKSHeader;
  49 typedef struct QCryptoBlockLUKSKeySlot QCryptoBlockLUKSKeySlot;
  50
  51
  52 /* The following constants are all defined by the LUKS spec */
  53 #define QCRYPTO_BLOCK_LUKS_VERSION 1
  54
  55 #define QCRYPTO_BLOCK_LUKS_MAGIC_LEN 6
  56 #define QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN 32
  57 #define QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN 32
  58 #define QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN 32
  59 #define QCRYPTO_BLOCK_LUKS_DIGEST_LEN 20
  60 #define QCRYPTO_BLOCK_LUKS_SALT_LEN 32
  61 #define QCRYPTO_BLOCK_LUKS_UUID_LEN 40
  62 #define QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS 8
  63 #define QCRYPTO_BLOCK_LUKS_STRIPES 4000
  64 #define QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS 1000
  65 #define QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS 1000
  66 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET 4096
  67
  68 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED 0x0000DEAD
  69 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED 0x00AC71F3
  70
  71 #define QCRYPTO_BLOCK_LUKS_SECTOR_SIZE 512LL
  72
  73 static const char qcrypto_block_luks_magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN] = {
  74     'L', 'U', 'K', 'S', 0xBA, 0xBE
  75 };
  76
  77 typedef struct QCryptoBlockLUKSNameMap QCryptoBlockLUKSNameMap;
  78 struct QCryptoBlockLUKSNameMap {
  79     const char *name;
  80     int id;
  81 };
  82
  83 typedef struct QCryptoBlockLUKSCipherSizeMap QCryptoBlockLUKSCipherSizeMap;
  84 struct QCryptoBlockLUKSCipherSizeMap {
  85     uint32_t key_bytes;
  86     int id;
  87 };
  88 typedef struct QCryptoBlockLUKSCipherNameMap QCryptoBlockLUKSCipherNameMap;
  89 struct QCryptoBlockLUKSCipherNameMap {
  90     const char *name;
  91     const QCryptoBlockLUKSCipherSizeMap *sizes;
  92 };
  93
  94
  95 static const QCryptoBlockLUKSCipherSizeMap
  96 qcrypto_block_luks_cipher_size_map_aes[] = {
  97     { 16, QCRYPTO_CIPHER_ALG_AES_128 },
  98     { 24, QCRYPTO_CIPHER_ALG_AES_192 },
  99     { 32, QCRYPTO_CIPHER_ALG_AES_256 },
 100     { 0, 0 },
 101 };
 102
 103 static const QCryptoBlockLUKSCipherSizeMap
 104 qcrypto_block_luks_cipher_size_map_cast5[] = {
 105     { 16, QCRYPTO_CIPHER_ALG_CAST5_128 },
 106     { 0, 0 },
 107 };
 108
 109 static const QCryptoBlockLUKSCipherSizeMap
 110 qcrypto_block_luks_cipher_size_map_serpent[] = {
 111     { 16, QCRYPTO_CIPHER_ALG_SERPENT_128 },
 112     { 24, QCRYPTO_CIPHER_ALG_SERPENT_192 },
 113     { 32, QCRYPTO_CIPHER_ALG_SERPENT_256 },
 114     { 0, 0 },
 115 };
 116
 117 static const QCryptoBlockLUKSCipherSizeMap
 118 qcrypto_block_luks_cipher_size_map_twofish[] = {
 119     { 16, QCRYPTO_CIPHER_ALG_TWOFISH_128 },
 120     { 24, QCRYPTO_CIPHER_ALG_TWOFISH_192 },
 121     { 32, QCRYPTO_CIPHER_ALG_TWOFISH_256 },
 122     { 0, 0 },
 123 };
 124
 125 static const QCryptoBlockLUKSCipherNameMap
 126 qcrypto_block_luks_cipher_name_map[] = {
 127     { "aes", qcrypto_block_luks_cipher_size_map_aes },
 128     { "cast5", qcrypto_block_luks_cipher_size_map_cast5 },
 129     { "serpent", qcrypto_block_luks_cipher_size_map_serpent },
 130     { "twofish", qcrypto_block_luks_cipher_size_map_twofish },
 131 };
 132
 133
 134 /*
 135  * This struct is written to disk in big-endian format,
 136  * but operated upon in native-endian format.
 137  */
 138 struct QCryptoBlockLUKSKeySlot {
 139     /* state of keyslot, enabled/disable */
 140     uint32_t active;
 141     /* iterations for PBKDF2 */
 142     uint32_t iterations;
 143     /* salt for PBKDF2 */
 144     uint8_t salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
 145     /* start sector of key material */
 146     uint32_t key_offset;
 147     /* number of anti-forensic stripes */
 148     uint32_t stripes;
 149 };
 150
 151 QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSKeySlot) != 48);
 152
 153
 154 /*
 155  * This struct is written to disk in big-endian format,
 156  * but operated upon in native-endian format.
 157  */
 158 struct QCryptoBlockLUKSHeader {
 159     /* 'L', 'U', 'K', 'S', '0xBA', '0xBE' */
 160     char magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN];
 161
 162     /* LUKS version, currently 1 */
 163     uint16_t version;
 164
 165     /* cipher name specification (aes, etc) */
 166     char cipher_name[QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN];
 167
 168     /* cipher mode specification (cbc-plain, xts-essiv:sha256, etc) */
 169     char cipher_mode[QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN];
 170
 171     /* hash specification (sha256, etc) */
 172     char hash_spec[QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN];
 173
 174     /* start offset of the volume data (in 512 byte sectors) */
 175     uint32_t payload_offset;
 176
 177     /* Number of key bytes */
 178     uint32_t key_bytes;
 179
 180     /* master key checksum after PBKDF2 */
 181     uint8_t master_key_digest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
 182
 183     /* salt for master key PBKDF2 */
 184     uint8_t master_key_salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
 185
 186     /* iterations for master key PBKDF2 */
 187     uint32_t master_key_iterations;
 188
 189     /* UUID of the partition in standard ASCII representation */
 190     uint8_t uuid[QCRYPTO_BLOCK_LUKS_UUID_LEN];
 191
 192     /* key slots */
 193     QCryptoBlockLUKSKeySlot key_slots[QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS];
 194 };
 195
 196 QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSHeader) != 592);
 197
 198
 199 struct QCryptoBlockLUKS {
 200     QCryptoBlockLUKSHeader header;
 201
 202     /* Cache parsed versions of what's in header fields,
 203      * as we can't rely on QCryptoBlock.cipher being
 204      * non-NULL */
 205     QCryptoCipherAlgorithm cipher_alg;
 206     QCryptoCipherMode cipher_mode;
 207     QCryptoIVGenAlgorithm ivgen_alg;
 208     QCryptoHashAlgorithm ivgen_hash_alg;
 209     QCryptoHashAlgorithm hash_alg;
 210 };
 211
 212
 213 static int qcrypto_block_luks_cipher_name_lookup(const char *name,
 214                                                  QCryptoCipherMode mode,
 215                                                  uint32_t key_bytes,
 216                                                  Error **errp)
 217 {
 218     const QCryptoBlockLUKSCipherNameMap *map =
 219         qcrypto_block_luks_cipher_name_map;
 220     size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
 221     size_t i, j;
 222
 223     if (mode == QCRYPTO_CIPHER_MODE_XTS) {
 224         key_bytes /= 2;
 225     }
 226
 227     for (i = 0; i < maplen; i++) {
 228         if (!g_str_equal(map[i].name, name)) {
 229             continue;
 230         }
 231         for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
 232             if (map[i].sizes[j].key_bytes == key_bytes) {
 233                 return map[i].sizes[j].id;
 234             }
 235         }
 236     }
 237
 238     error_setg(errp, "Algorithm %s with key size %d bytes not supported",
 239                name, key_bytes);
 240     return 0;
 241 }
 242
 243 static const char *
 244 qcrypto_block_luks_cipher_alg_lookup(QCryptoCipherAlgorithm alg,
 245                                      Error **errp)
 246 {
 247     const QCryptoBlockLUKSCipherNameMap *map =
 248         qcrypto_block_luks_cipher_name_map;
 249     size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
 250     size_t i, j;
 251     for (i = 0; i < maplen; i++) {
 252         for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
 253             if (map[i].sizes[j].id == alg) {
 254                 return map[i].name;
 255             }
 256         }
 257     }
 258
 259     error_setg(errp, "Algorithm '%s' not supported",
 260                QCryptoCipherAlgorithm_str(alg));
 261     return NULL;
 262 }
 263
 264 /* XXX replace with qapi_enum_parse() in future, when we can
 265  * make that function emit a more friendly error message */
 266 static int qcrypto_block_luks_name_lookup(const char *name,
 267                                           const QEnumLookup *map,
 268                                           const char *type,
 269                                           Error **errp)
 270 {
 271     int ret = qapi_enum_parse(map, name, -1, NULL);
 272
 273     if (ret < 0) {
 274         error_setg(errp, "%s %s not supported", type, name);
 275         return 0;
 276     }
 277     return ret;
 278 }
 279
 280 #define qcrypto_block_luks_cipher_mode_lookup(name, errp)               \
 281     qcrypto_block_luks_name_lookup(name,                                \
 282                                    &QCryptoCipherMode_lookup,           \
 283                                    "Cipher mode",                       \
 284                                    errp)
 285
 286 #define qcrypto_block_luks_hash_name_lookup(name, errp)                 \
 287     qcrypto_block_luks_name_lookup(name,                                \
 288                                    &QCryptoHashAlgorithm_lookup,        \
 289                                    "Hash algorithm",                    \
 290                                    errp)
 291
 292 #define qcrypto_block_luks_ivgen_name_lookup(name, errp)                \
 293     qcrypto_block_luks_name_lookup(name,                                \
 294                                    &QCryptoIVGenAlgorithm_lookup,       \
 295                                    "IV generator",                      \
 296                                    errp)
 297
 298
 299 static bool
 300 qcrypto_block_luks_has_format(const uint8_t *buf,
 301                               size_t buf_size)
 302 {
 303     const QCryptoBlockLUKSHeader *luks_header = (const void *)buf;
 304
 305     if (buf_size >= offsetof(QCryptoBlockLUKSHeader, cipher_name) &&
 306         memcmp(luks_header->magic, qcrypto_block_luks_magic,
 307                QCRYPTO_BLOCK_LUKS_MAGIC_LEN) == 0 &&
 308         be16_to_cpu(luks_header->version) == QCRYPTO_BLOCK_LUKS_VERSION) {
 309         return true;
 310     } else {
 311         return false;
 312     }
 313 }
 314
 315
 316 /**
 317  * Deal with a quirk of dm-crypt usage of ESSIV.
 318  *
 319  * When calculating ESSIV IVs, the cipher length used by ESSIV
 320  * may be different from the cipher length used for the block
 321  * encryption, becauses dm-crypt uses the hash digest length
 322  * as the key size. ie, if you have AES 128 as the block cipher
 323  * and SHA 256 as ESSIV hash, then ESSIV will use AES 256 as
 324  * the cipher since that gets a key length matching the digest
 325  * size, not AES 128 with truncated digest as might be imagined
 326  */
 327 static QCryptoCipherAlgorithm
 328 qcrypto_block_luks_essiv_cipher(QCryptoCipherAlgorithm cipher,
 329                                 QCryptoHashAlgorithm hash,
 330                                 Error **errp)
 331 {
 332     size_t digestlen = qcrypto_hash_digest_len(hash);
 333     size_t keylen = qcrypto_cipher_get_key_len(cipher);
 334     if (digestlen == keylen) {
 335         return cipher;
 336     }
 337
 338     switch (cipher) {
 339     case QCRYPTO_CIPHER_ALG_AES_128:
 340     case QCRYPTO_CIPHER_ALG_AES_192:
 341     case QCRYPTO_CIPHER_ALG_AES_256:
 342         if (digestlen == qcrypto_cipher_get_key_len(
 343                 QCRYPTO_CIPHER_ALG_AES_128)) {
 344             return QCRYPTO_CIPHER_ALG_AES_128;
 345         } else if (digestlen == qcrypto_cipher_get_key_len(
 346                        QCRYPTO_CIPHER_ALG_AES_192)) {
 347             return QCRYPTO_CIPHER_ALG_AES_192;
 348         } else if (digestlen == qcrypto_cipher_get_key_len(
 349                        QCRYPTO_CIPHER_ALG_AES_256)) {
 350             return QCRYPTO_CIPHER_ALG_AES_256;
 351         } else {
 352             error_setg(errp, "No AES cipher with key size %zu available",
 353                        digestlen);
 354             return 0;
 355         }
 356         break;
 357     case QCRYPTO_CIPHER_ALG_SERPENT_128:
 358     case QCRYPTO_CIPHER_ALG_SERPENT_192:
 359     case QCRYPTO_CIPHER_ALG_SERPENT_256:
 360         if (digestlen == qcrypto_cipher_get_key_len(
 361                 QCRYPTO_CIPHER_ALG_SERPENT_128)) {
 362             return QCRYPTO_CIPHER_ALG_SERPENT_128;
 363         } else if (digestlen == qcrypto_cipher_get_key_len(
 364                        QCRYPTO_CIPHER_ALG_SERPENT_192)) {
 365             return QCRYPTO_CIPHER_ALG_SERPENT_192;
 366         } else if (digestlen == qcrypto_cipher_get_key_len(
 367                        QCRYPTO_CIPHER_ALG_SERPENT_256)) {
 368             return QCRYPTO_CIPHER_ALG_SERPENT_256;
 369         } else {
 370             error_setg(errp, "No Serpent cipher with key size %zu available",
 371                        digestlen);
 372             return 0;
 373         }
 374         break;
 375     case QCRYPTO_CIPHER_ALG_TWOFISH_128:
 376     case QCRYPTO_CIPHER_ALG_TWOFISH_192:
 377     case QCRYPTO_CIPHER_ALG_TWOFISH_256:
 378         if (digestlen == qcrypto_cipher_get_key_len(
 379                 QCRYPTO_CIPHER_ALG_TWOFISH_128)) {
 380             return QCRYPTO_CIPHER_ALG_TWOFISH_128;
 381         } else if (digestlen == qcrypto_cipher_get_key_len(
 382                        QCRYPTO_CIPHER_ALG_TWOFISH_192)) {
 383             return QCRYPTO_CIPHER_ALG_TWOFISH_192;
 384         } else if (digestlen == qcrypto_cipher_get_key_len(
 385                        QCRYPTO_CIPHER_ALG_TWOFISH_256)) {
 386             return QCRYPTO_CIPHER_ALG_TWOFISH_256;
 387         } else {
 388             error_setg(errp, "No Twofish cipher with key size %zu available",
 389                        digestlen);
 390             return 0;
 391         }
 392         break;
 393     default:
 394         error_setg(errp, "Cipher %s not supported with essiv",
 395                    QCryptoCipherAlgorithm_str(cipher));
 396         return 0;
 397     }
 398 }
 399
 400 /*
 401  * Given a key slot, and user password, this will attempt to unlock
 402  * the master encryption key from the key slot.
 403  *
 404  * Returns:
 405  *    0 if the key slot is disabled, or key could not be decrypted
 406  *      with the provided password
 407  *    1 if the key slot is enabled, and key decrypted successfully
 408  *      with the provided password
 409  *   -1 if a fatal error occurred loading the key
 410  */
 411 static int
 412 qcrypto_block_luks_load_key(QCryptoBlock *block,
 413                             QCryptoBlockLUKSKeySlot *slot,
 414                             const char *password,
 415                             QCryptoCipherAlgorithm cipheralg,
 416                             QCryptoCipherMode ciphermode,
 417                             QCryptoHashAlgorithm hash,
 418                             QCryptoIVGenAlgorithm ivalg,
 419                             QCryptoCipherAlgorithm ivcipheralg,
 420                             QCryptoHashAlgorithm ivhash,
 421                             uint8_t *masterkey,
 422                             size_t masterkeylen,
 423                             QCryptoBlockReadFunc readfunc,
 424                             void *opaque,
 425                             Error **errp)
 426 {
 427     QCryptoBlockLUKS *luks = block->opaque;
 428     uint8_t *splitkey;
 429     size_t splitkeylen;
 430     uint8_t *possiblekey;
 431     int ret = -1;
 432     ssize_t rv;
 433     QCryptoCipher *cipher = NULL;
 434     uint8_t keydigest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
 435     QCryptoIVGen *ivgen = NULL;
 436     size_t niv;
 437
 438     if (slot->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
 439         return 0;
 440     }
 441
 442     splitkeylen = masterkeylen * slot->stripes;
 443     splitkey = g_new0(uint8_t, splitkeylen);
 444     possiblekey = g_new0(uint8_t, masterkeylen);
 445
 446     /*
 447      * The user password is used to generate a (possible)
 448      * decryption key. This may or may not successfully
 449      * decrypt the master key - we just blindly assume
 450      * the key is correct and validate the results of
 451      * decryption later.
 452      */
 453     if (qcrypto_pbkdf2(hash,
 454                        (const uint8_t *)password, strlen(password),
 455                        slot->salt, QCRYPTO_BLOCK_LUKS_SALT_LEN,
 456                        slot->iterations,
 457                        possiblekey, masterkeylen,
 458                        errp) < 0) {
 459         goto cleanup;
 460     }
 461
 462     /*
 463      * We need to read the master key material from the
 464      * LUKS key material header. What we're reading is
 465      * not the raw master key, but rather the data after
 466      * it has been passed through AFSplit and the result
 467      * then encrypted.
 468      */
 469     rv = readfunc(block,
 470                   slot->key_offset * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 471                   splitkey, splitkeylen,
 472                   opaque,
 473                   errp);
 474     if (rv < 0) {
 475         goto cleanup;
 476     }
 477
 478
 479     /* Setup the cipher/ivgen that we'll use to try to decrypt
 480      * the split master key material */
 481     cipher = qcrypto_cipher_new(cipheralg, ciphermode,
 482                                 possiblekey, masterkeylen,
 483                                 errp);
 484     if (!cipher) {
 485         goto cleanup;
 486     }
 487
 488     niv = qcrypto_cipher_get_iv_len(cipheralg,
 489                                     ciphermode);
 490     ivgen = qcrypto_ivgen_new(ivalg,
 491                               ivcipheralg,
 492                               ivhash,
 493                               possiblekey, masterkeylen,
 494                               errp);
 495     if (!ivgen) {
 496         goto cleanup;
 497     }
 498
 499
 500     /*
 501      * The master key needs to be decrypted in the same
 502      * way that the block device payload will be decrypted
 503      * later. In particular we'll be using the IV generator
 504      * to reset the encryption cipher every time the master
 505      * key crosses a sector boundary.
 506      */
 507     if (qcrypto_block_cipher_decrypt_helper(cipher,
 508                                             niv,
 509                                             ivgen,
 510                                             QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 511                                             0,
 512                                             splitkey,
 513                                             splitkeylen,
 514                                             errp) < 0) {
 515         goto cleanup;
 516     }
 517
 518     /*
 519      * Now we've decrypted the split master key, join
 520      * it back together to get the actual master key.
 521      */
 522     if (qcrypto_afsplit_decode(hash,
 523                                masterkeylen,
 524                                slot->stripes,
 525                                splitkey,
 526                                masterkey,
 527                                errp) < 0) {
 528         goto cleanup;
 529     }
 530
 531
 532     /*
 533      * We still don't know that the masterkey we got is valid,
 534      * because we just blindly assumed the user's password
 535      * was correct. This is where we now verify it. We are
 536      * creating a hash of the master key using PBKDF and
 537      * then comparing that to the hash stored in the key slot
 538      * header
 539      */
 540     if (qcrypto_pbkdf2(hash,
 541                        masterkey, masterkeylen,
 542                        luks->header.master_key_salt,
 543                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
 544                        luks->header.master_key_iterations,
 545                        keydigest, G_N_ELEMENTS(keydigest),
 546                        errp) < 0) {
 547         goto cleanup;
 548     }
 549
 550     if (memcmp(keydigest, luks->header.master_key_digest,
 551                QCRYPTO_BLOCK_LUKS_DIGEST_LEN) == 0) {
 552         /* Success, we got the right master key */
 553         ret = 1;
 554         goto cleanup;
 555     }
 556
 557     /* Fail, user's password was not valid for this key slot,
 558      * tell caller to try another slot */
 559     ret = 0;
 560
 561  cleanup:
 562     qcrypto_ivgen_free(ivgen);
 563     qcrypto_cipher_free(cipher);
 564     g_free(splitkey);
 565     g_free(possiblekey);
 566     return ret;
 567 }
 568
 569
 570 /*
 571  * Given a user password, this will iterate over all key
 572  * slots and try to unlock each active key slot using the
 573  * password until it successfully obtains a master key.
 574  *
 575  * Returns 0 if a key was loaded, -1 if no keys could be loaded
 576  */
 577 static int
 578 qcrypto_block_luks_find_key(QCryptoBlock *block,
 579                             const char *password,
 580                             QCryptoCipherAlgorithm cipheralg,
 581                             QCryptoCipherMode ciphermode,
 582                             QCryptoHashAlgorithm hash,
 583                             QCryptoIVGenAlgorithm ivalg,
 584                             QCryptoCipherAlgorithm ivcipheralg,
 585                             QCryptoHashAlgorithm ivhash,
 586                             uint8_t **masterkey,
 587                             size_t *masterkeylen,
 588                             QCryptoBlockReadFunc readfunc,
 589                             void *opaque,
 590                             Error **errp)
 591 {
 592     QCryptoBlockLUKS *luks = block->opaque;
 593     size_t i;
 594     int rv;
 595
 596     *masterkey = g_new0(uint8_t, luks->header.key_bytes);
 597     *masterkeylen = luks->header.key_bytes;
 598
 599     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
 600         rv = qcrypto_block_luks_load_key(block,
 601                                          &luks->header.key_slots[i],
 602                                          password,
 603                                          cipheralg,
 604                                          ciphermode,
 605                                          hash,
 606                                          ivalg,
 607                                          ivcipheralg,
 608                                          ivhash,
 609                                          *masterkey,
 610                                          *masterkeylen,
 611                                          readfunc,
 612                                          opaque,
 613                                          errp);
 614         if (rv < 0) {
 615             goto error;
 616         }
 617         if (rv == 1) {
 618             return 0;
 619         }
 620     }
 621
 622     error_setg(errp, "Invalid password, cannot unlock any keyslot");
 623
 624  error:
 625     g_free(*masterkey);
 626     *masterkey = NULL;
 627     *masterkeylen = 0;
 628     return -1;
 629 }
 630
 631
 632 static int
 633 qcrypto_block_luks_open(QCryptoBlock *block,
 634                         QCryptoBlockOpenOptions *options,
 635                         const char *optprefix,
 636                         QCryptoBlockReadFunc readfunc,
 637                         void *opaque,
 638                         unsigned int flags,
 639                         size_t n_threads,
 640                         Error **errp)
 641 {
 642     QCryptoBlockLUKS *luks;
 643     Error *local_err = NULL;
 644     int ret = 0;
 645     size_t i;
 646     ssize_t rv;
 647     uint8_t *masterkey = NULL;
 648     size_t masterkeylen;
 649     char *ivgen_name, *ivhash_name;
 650     QCryptoCipherMode ciphermode;
 651     QCryptoCipherAlgorithm cipheralg;
 652     QCryptoIVGenAlgorithm ivalg;
 653     QCryptoCipherAlgorithm ivcipheralg;
 654     QCryptoHashAlgorithm hash;
 655     QCryptoHashAlgorithm ivhash;
 656     char *password = NULL;
 657
 658     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
 659         if (!options->u.luks.key_secret) {
 660             error_setg(errp, "Parameter '%skey-secret' is required for cipher",
 661                        optprefix ? optprefix : "");
 662             return -1;
 663         }
 664         password = qcrypto_secret_lookup_as_utf8(
 665             options->u.luks.key_secret, errp);
 666         if (!password) {
 667             return -1;
 668         }
 669     }
 670
 671     luks = g_new0(QCryptoBlockLUKS, 1);
 672     block->opaque = luks;
 673
 674     /* Read the entire LUKS header, minus the key material from
 675      * the underlying device */
 676     rv = readfunc(block, 0,
 677                   (uint8_t *)&luks->header,
 678                   sizeof(luks->header),
 679                   opaque,
 680                   errp);
 681     if (rv < 0) {
 682         ret = rv;
 683         goto fail;
 684     }
 685
 686     /* The header is always stored in big-endian format, so
 687      * convert everything to native */
 688     be16_to_cpus(&luks->header.version);
 689     be32_to_cpus(&luks->header.payload_offset);
 690     be32_to_cpus(&luks->header.key_bytes);
 691     be32_to_cpus(&luks->header.master_key_iterations);
 692
 693     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
 694         be32_to_cpus(&luks->header.key_slots[i].active);
 695         be32_to_cpus(&luks->header.key_slots[i].iterations);
 696         be32_to_cpus(&luks->header.key_slots[i].key_offset);
 697         be32_to_cpus(&luks->header.key_slots[i].stripes);
 698     }
 699
 700     if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
 701                QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
 702         error_setg(errp, "Volume is not in LUKS format");
 703         ret = -EINVAL;
 704         goto fail;
 705     }
 706     if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
 707         error_setg(errp, "LUKS version %" PRIu32 " is not supported",
 708                    luks->header.version);
 709         ret = -ENOTSUP;
 710         goto fail;
 711     }
 712
 713     /*
 714      * The cipher_mode header contains a string that we have
 715      * to further parse, of the format
 716      *
 717      *    <cipher-mode>-<iv-generator>[:<iv-hash>]
 718      *
 719      * eg  cbc-essiv:sha256, cbc-plain64
 720      */
 721     ivgen_name = strchr(luks->header.cipher_mode, '-');
 722     if (!ivgen_name) {
 723         ret = -EINVAL;
 724         error_setg(errp, "Unexpected cipher mode string format %s",
 725                    luks->header.cipher_mode);
 726         goto fail;
 727     }
 728     *ivgen_name = '\0';
 729     ivgen_name++;
 730
 731     ivhash_name = strchr(ivgen_name, ':');
 732     if (!ivhash_name) {
 733         ivhash = 0;
 734     } else {
 735         *ivhash_name = '\0';
 736         ivhash_name++;
 737
 738         ivhash = qcrypto_block_luks_hash_name_lookup(ivhash_name,
 739                                                      &local_err);
 740         if (local_err) {
 741             ret = -ENOTSUP;
 742             error_propagate(errp, local_err);
 743             goto fail;
 744         }
 745     }
 746
 747     ciphermode = qcrypto_block_luks_cipher_mode_lookup(luks->header.cipher_mode,
 748                                                        &local_err);
 749     if (local_err) {
 750         ret = -ENOTSUP;
 751         error_propagate(errp, local_err);
 752         goto fail;
 753     }
 754
 755     cipheralg = qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
 756                                                       ciphermode,
 757                                                       luks->header.key_bytes,
 758                                                       &local_err);
 759     if (local_err) {
 760         ret = -ENOTSUP;
 761         error_propagate(errp, local_err);
 762         goto fail;
 763     }
 764
 765     hash = qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
 766                                                &local_err);
 767     if (local_err) {
 768         ret = -ENOTSUP;
 769         error_propagate(errp, local_err);
 770         goto fail;
 771     }
 772
 773     ivalg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
 774                                                  &local_err);
 775     if (local_err) {
 776         ret = -ENOTSUP;
 777         error_propagate(errp, local_err);
 778         goto fail;
 779     }
 780
 781     if (ivalg == QCRYPTO_IVGEN_ALG_ESSIV) {
 782         if (!ivhash_name) {
 783             ret = -EINVAL;
 784             error_setg(errp, "Missing IV generator hash specification");
 785             goto fail;
 786         }
 787         ivcipheralg = qcrypto_block_luks_essiv_cipher(cipheralg,
 788                                                       ivhash,
 789                                                       &local_err);
 790         if (local_err) {
 791             ret = -ENOTSUP;
 792             error_propagate(errp, local_err);
 793             goto fail;
 794         }
 795     } else {
 796         /* Note we parsed the ivhash_name earlier in the cipher_mode
 797          * spec string even with plain/plain64 ivgens, but we
 798          * will ignore it, since it is irrelevant for these ivgens.
 799          * This is for compat with dm-crypt which will silently
 800          * ignore hash names with these ivgens rather than report
 801          * an error about the invalid usage
 802          */
 803         ivcipheralg = cipheralg;
 804     }
 805
 806     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
 807         /* Try to find which key slot our password is valid for
 808          * and unlock the master key from that slot.
 809          */
 810         if (qcrypto_block_luks_find_key(block,
 811                                         password,
 812                                         cipheralg, ciphermode,
 813                                         hash,
 814                                         ivalg,
 815                                         ivcipheralg,
 816                                         ivhash,
 817                                         &masterkey, &masterkeylen,
 818                                         readfunc, opaque,
 819                                         errp) < 0) {
 820             ret = -EACCES;
 821             goto fail;
 822         }
 823
 824         /* We have a valid master key now, so can setup the
 825          * block device payload decryption objects
 826          */
 827         block->kdfhash = hash;
 828         block->niv = qcrypto_cipher_get_iv_len(cipheralg,
 829                                                ciphermode);
 830         block->ivgen = qcrypto_ivgen_new(ivalg,
 831                                          ivcipheralg,
 832                                          ivhash,
 833                                          masterkey, masterkeylen,
 834                                          errp);
 835         if (!block->ivgen) {
 836             ret = -ENOTSUP;
 837             goto fail;
 838         }
 839
 840         ret = qcrypto_block_init_cipher(block, cipheralg, ciphermode,
 841                                         masterkey, masterkeylen, n_threads,
 842                                         errp);
 843         if (ret < 0) {
 844             ret = -ENOTSUP;
 845             goto fail;
 846         }
 847     }
 848
 849     block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
 850     block->payload_offset = luks->header.payload_offset *
 851         block->sector_size;
 852
 853     luks->cipher_alg = cipheralg;
 854     luks->cipher_mode = ciphermode;
 855     luks->ivgen_alg = ivalg;
 856     luks->ivgen_hash_alg = ivhash;
 857     luks->hash_alg = hash;
 858
 859     g_free(masterkey);
 860     g_free(password);
 861
 862     return 0;
 863
 864  fail:
 865     g_free(masterkey);
 866     qcrypto_block_free_cipher(block);
 867     qcrypto_ivgen_free(block->ivgen);
 868     g_free(luks);
 869     g_free(password);
 870     return ret;
 871 }
 872
 873
 874 static void
 875 qcrypto_block_luks_uuid_gen(uint8_t *uuidstr)
 876 {
 877     QemuUUID uuid;
 878     qemu_uuid_generate(&uuid);
 879     qemu_uuid_unparse(&uuid, (char *)uuidstr);
 880 }
 881
 882 static int
 883 qcrypto_block_luks_create(QCryptoBlock *block,
 884                           QCryptoBlockCreateOptions *options,
 885                           const char *optprefix,
 886                           QCryptoBlockInitFunc initfunc,
 887                           QCryptoBlockWriteFunc writefunc,
 888                           void *opaque,
 889                           Error **errp)
 890 {
 891     QCryptoBlockLUKS *luks;
 892     QCryptoBlockCreateOptionsLUKS luks_opts;
 893     Error *local_err = NULL;
 894     uint8_t *masterkey = NULL;
 895     uint8_t *slotkey = NULL;
 896     uint8_t *splitkey = NULL;
 897     size_t splitkeylen = 0;
 898     size_t i;
 899     QCryptoCipher *cipher = NULL;
 900     QCryptoIVGen *ivgen = NULL;
 901     char *password;
 902     const char *cipher_alg;
 903     const char *cipher_mode;
 904     const char *ivgen_alg;
 905     const char *ivgen_hash_alg = NULL;
 906     const char *hash_alg;
 907     char *cipher_mode_spec = NULL;
 908     QCryptoCipherAlgorithm ivcipheralg = 0;
 909     uint64_t iters;
 910
 911     memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
 912     if (!luks_opts.has_iter_time) {
 913         luks_opts.iter_time = 2000;
 914     }
 915     if (!luks_opts.has_cipher_alg) {
 916         luks_opts.cipher_alg = QCRYPTO_CIPHER_ALG_AES_256;
 917     }
 918     if (!luks_opts.has_cipher_mode) {
 919         luks_opts.cipher_mode = QCRYPTO_CIPHER_MODE_XTS;
 920     }
 921     if (!luks_opts.has_ivgen_alg) {
 922         luks_opts.ivgen_alg = QCRYPTO_IVGEN_ALG_PLAIN64;
 923     }
 924     if (!luks_opts.has_hash_alg) {
 925         luks_opts.hash_alg = QCRYPTO_HASH_ALG_SHA256;
 926     }
 927     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
 928         if (!luks_opts.has_ivgen_hash_alg) {
 929             luks_opts.ivgen_hash_alg = QCRYPTO_HASH_ALG_SHA256;
 930             luks_opts.has_ivgen_hash_alg = true;
 931         }
 932     }
 933     /* Note we're allowing ivgen_hash_alg to be set even for
 934      * non-essiv iv generators that don't need a hash. It will
 935      * be silently ignored, for compatibility with dm-crypt */
 936
 937     if (!options->u.luks.key_secret) {
 938         error_setg(errp, "Parameter '%skey-secret' is required for cipher",
 939                    optprefix ? optprefix : "");
 940         return -1;
 941     }
 942     password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret, errp);
 943     if (!password) {
 944         return -1;
 945     }
 946
 947     luks = g_new0(QCryptoBlockLUKS, 1);
 948     block->opaque = luks;
 949
 950     memcpy(luks->header.magic, qcrypto_block_luks_magic,
 951            QCRYPTO_BLOCK_LUKS_MAGIC_LEN);
 952
 953     /* We populate the header in native endianness initially and
 954      * then convert everything to big endian just before writing
 955      * it out to disk
 956      */
 957     luks->header.version = QCRYPTO_BLOCK_LUKS_VERSION;
 958     qcrypto_block_luks_uuid_gen(luks->header.uuid);
 959
 960     cipher_alg = qcrypto_block_luks_cipher_alg_lookup(luks_opts.cipher_alg,
 961                                                       errp);
 962     if (!cipher_alg) {
 963         goto error;
 964     }
 965
 966     cipher_mode = QCryptoCipherMode_str(luks_opts.cipher_mode);
 967     ivgen_alg = QCryptoIVGenAlgorithm_str(luks_opts.ivgen_alg);
 968     if (luks_opts.has_ivgen_hash_alg) {
 969         ivgen_hash_alg = QCryptoHashAlgorithm_str(luks_opts.ivgen_hash_alg);
 970         cipher_mode_spec = g_strdup_printf("%s-%s:%s", cipher_mode, ivgen_alg,
 971                                            ivgen_hash_alg);
 972     } else {
 973         cipher_mode_spec = g_strdup_printf("%s-%s", cipher_mode, ivgen_alg);
 974     }
 975     hash_alg = QCryptoHashAlgorithm_str(luks_opts.hash_alg);
 976
 977
 978     if (strlen(cipher_alg) >= QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN) {
 979         error_setg(errp, "Cipher name '%s' is too long for LUKS header",
 980                    cipher_alg);
 981         goto error;
 982     }
 983     if (strlen(cipher_mode_spec) >= QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN) {
 984         error_setg(errp, "Cipher mode '%s' is too long for LUKS header",
 985                    cipher_mode_spec);
 986         goto error;
 987     }
 988     if (strlen(hash_alg) >= QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN) {
 989         error_setg(errp, "Hash name '%s' is too long for LUKS header",
 990                    hash_alg);
 991         goto error;
 992     }
 993
 994     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
 995         ivcipheralg = qcrypto_block_luks_essiv_cipher(luks_opts.cipher_alg,
 996                                                       luks_opts.ivgen_hash_alg,
 997                                                       &local_err);
 998         if (local_err) {
 999             error_propagate(errp, local_err);
1000             goto error;
1001         }
1002     } else {
1003         ivcipheralg = luks_opts.cipher_alg;
1004     }
1005
1006     strcpy(luks->header.cipher_name, cipher_alg);
1007     strcpy(luks->header.cipher_mode, cipher_mode_spec);
1008     strcpy(luks->header.hash_spec, hash_alg);
1009
1010     luks->header.key_bytes = qcrypto_cipher_get_key_len(luks_opts.cipher_alg);
1011     if (luks_opts.cipher_mode == QCRYPTO_CIPHER_MODE_XTS) {
1012         luks->header.key_bytes *= 2;
1013     }
1014
1015     /* Generate the salt used for hashing the master key
1016      * with PBKDF later
1017      */
1018     if (qcrypto_random_bytes(luks->header.master_key_salt,
1019                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1020                              errp) < 0) {
1021         goto error;
1022     }
1023
1024     /* Generate random master key */
1025     masterkey = g_new0(uint8_t, luks->header.key_bytes);
1026     if (qcrypto_random_bytes(masterkey,
1027                              luks->header.key_bytes, errp) < 0) {
1028         goto error;
1029     }
1030
1031
1032     /* Setup the block device payload encryption objects */
1033     if (qcrypto_block_init_cipher(block, luks_opts.cipher_alg,
1034                                   luks_opts.cipher_mode, masterkey,
1035                                   luks->header.key_bytes, 1, errp) < 0) {
1036         goto error;
1037     }
1038
1039     block->kdfhash = luks_opts.hash_alg;
1040     block->niv = qcrypto_cipher_get_iv_len(luks_opts.cipher_alg,
1041                                            luks_opts.cipher_mode);
1042     block->ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1043                                      ivcipheralg,
1044                                      luks_opts.ivgen_hash_alg,
1045                                      masterkey, luks->header.key_bytes,
1046                                      errp);
1047
1048     if (!block->ivgen) {
1049         goto error;
1050     }
1051
1052
1053     /* Determine how many iterations we need to hash the master
1054      * key, in order to have 1 second of compute time used
1055      */
1056     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1057                                        masterkey, luks->header.key_bytes,
1058                                        luks->header.master_key_salt,
1059                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1060                                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1061                                        &local_err);
1062     if (local_err) {
1063         error_propagate(errp, local_err);
1064         goto error;
1065     }
1066
1067     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1068         error_setg_errno(errp, ERANGE,
1069                          "PBKDF iterations %llu too large to scale",
1070                          (unsigned long long)iters);
1071         goto error;
1072     }
1073
1074     /* iter_time was in millis, but count_iters reported for secs */
1075     iters = iters * luks_opts.iter_time / 1000;
1076
1077     /* Why /= 8 ?  That matches cryptsetup, but there's no
1078      * explanation why they chose /= 8... Probably so that
1079      * if all 8 keyslots are active we only spend 1 second
1080      * in total time to check all keys */
1081     iters /= 8;
1082     if (iters > UINT32_MAX) {
1083         error_setg_errno(errp, ERANGE,
1084                          "PBKDF iterations %llu larger than %u",
1085                          (unsigned long long)iters, UINT32_MAX);
1086         goto error;
1087     }
1088     iters = MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS);
1089     luks->header.master_key_iterations = iters;
1090
1091     /* Hash the master key, saving the result in the LUKS
1092      * header. This hash is used when opening the encrypted
1093      * device to verify that the user password unlocked a
1094      * valid master key
1095      */
1096     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1097                        masterkey, luks->header.key_bytes,
1098                        luks->header.master_key_salt,
1099                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1100                        luks->header.master_key_iterations,
1101                        luks->header.master_key_digest,
1102                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1103                        errp) < 0) {
1104         goto error;
1105     }
1106
1107
1108     /* Although LUKS has multiple key slots, we're just going
1109      * to use the first key slot */
1110     splitkeylen = luks->header.key_bytes * QCRYPTO_BLOCK_LUKS_STRIPES;
1111     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1112         luks->header.key_slots[i].active = i == 0 ?
1113             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED :
1114             QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
1115         luks->header.key_slots[i].stripes = QCRYPTO_BLOCK_LUKS_STRIPES;
1116
1117         /* This calculation doesn't match that shown in the spec,
1118          * but instead follows the cryptsetup implementation.
1119          */
1120         luks->header.key_slots[i].key_offset =
1121             (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1122              QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1123             (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1124                       (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1125                        QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) * i);
1126     }
1127
1128     if (qcrypto_random_bytes(luks->header.key_slots[0].salt,
1129                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1130                              errp) < 0) {
1131         goto error;
1132     }
1133
1134     /* Again we determine how many iterations are required to
1135      * hash the user password while consuming 1 second of compute
1136      * time */
1137     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1138                                        (uint8_t *)password, strlen(password),
1139                                        luks->header.key_slots[0].salt,
1140                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1141                                        luks->header.key_bytes,
1142                                        &local_err);
1143     if (local_err) {
1144         error_propagate(errp, local_err);
1145         goto error;
1146     }
1147
1148     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1149         error_setg_errno(errp, ERANGE,
1150                          "PBKDF iterations %llu too large to scale",
1151                          (unsigned long long)iters);
1152         goto error;
1153     }
1154
1155     /* iter_time was in millis, but count_iters reported for secs */
1156     iters = iters * luks_opts.iter_time / 1000;
1157
1158     if (iters > UINT32_MAX) {
1159         error_setg_errno(errp, ERANGE,
1160                          "PBKDF iterations %llu larger than %u",
1161                          (unsigned long long)iters, UINT32_MAX);
1162         goto error;
1163     }
1164
1165     luks->header.key_slots[0].iterations =
1166         MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);
1167
1168
1169     /* Generate a key that we'll use to encrypt the master
1170      * key, from the user's password
1171      */
1172     slotkey = g_new0(uint8_t, luks->header.key_bytes);
1173     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1174                        (uint8_t *)password, strlen(password),
1175                        luks->header.key_slots[0].salt,
1176                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1177                        luks->header.key_slots[0].iterations,
1178                        slotkey, luks->header.key_bytes,
1179                        errp) < 0) {
1180         goto error;
1181     }
1182
1183
1184     /* Setup the encryption objects needed to encrypt the
1185      * master key material
1186      */
1187     cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
1188                                 luks_opts.cipher_mode,
1189                                 slotkey, luks->header.key_bytes,
1190                                 errp);
1191     if (!cipher) {
1192         goto error;
1193     }
1194
1195     ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1196                               ivcipheralg,
1197                               luks_opts.ivgen_hash_alg,
1198                               slotkey, luks->header.key_bytes,
1199                               errp);
1200     if (!ivgen) {
1201         goto error;
1202     }
1203
1204     /* Before storing the master key, we need to vastly
1205      * increase its size, as protection against forensic
1206      * disk data recovery */
1207     splitkey = g_new0(uint8_t, splitkeylen);
1208
1209     if (qcrypto_afsplit_encode(luks_opts.hash_alg,
1210                                luks->header.key_bytes,
1211                                luks->header.key_slots[0].stripes,
1212                                masterkey,
1213                                splitkey,
1214                                errp) < 0) {
1215         goto error;
1216     }
1217
1218     /* Now we encrypt the split master key with the key generated
1219      * from the user's password, before storing it */
1220     if (qcrypto_block_cipher_encrypt_helper(cipher, block->niv, ivgen,
1221                                             QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1222                                             0,
1223                                             splitkey,
1224                                             splitkeylen,
1225                                             errp) < 0) {
1226         goto error;
1227     }
1228
1229
1230     /* The total size of the LUKS headers is the partition header + key
1231      * slot headers, rounded up to the nearest sector, combined with
1232      * the size of each master key material region, also rounded up
1233      * to the nearest sector */
1234     luks->header.payload_offset =
1235         (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1236          QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1237         (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1238                   (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1239                    QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) *
1240          QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
1241
1242     block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1243     block->payload_offset = luks->header.payload_offset *
1244         block->sector_size;
1245
1246     /* Reserve header space to match payload offset */
1247     initfunc(block, block->payload_offset, opaque, &local_err);
1248     if (local_err) {
1249         error_propagate(errp, local_err);
1250         goto error;
1251     }
1252
1253     /* Everything on disk uses Big Endian, so flip header fields
1254      * before writing them */
1255     cpu_to_be16s(&luks->header.version);
1256     cpu_to_be32s(&luks->header.payload_offset);
1257     cpu_to_be32s(&luks->header.key_bytes);
1258     cpu_to_be32s(&luks->header.master_key_iterations);
1259
1260     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1261         cpu_to_be32s(&luks->header.key_slots[i].active);
1262         cpu_to_be32s(&luks->header.key_slots[i].iterations);
1263         cpu_to_be32s(&luks->header.key_slots[i].key_offset);
1264         cpu_to_be32s(&luks->header.key_slots[i].stripes);
1265     }
1266
1267
1268     /* Write out the partition header and key slot headers */
1269     writefunc(block, 0,
1270               (const uint8_t *)&luks->header,
1271               sizeof(luks->header),
1272               opaque,
1273               &local_err);
1274
1275     /* Delay checking local_err until we've byte-swapped */
1276
1277     /* Byte swap the header back to native, in case we need
1278      * to read it again later */
1279     be16_to_cpus(&luks->header.version);
1280     be32_to_cpus(&luks->header.payload_offset);
1281     be32_to_cpus(&luks->header.key_bytes);
1282     be32_to_cpus(&luks->header.master_key_iterations);
1283
1284     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1285         be32_to_cpus(&luks->header.key_slots[i].active);
1286         be32_to_cpus(&luks->header.key_slots[i].iterations);
1287         be32_to_cpus(&luks->header.key_slots[i].key_offset);
1288         be32_to_cpus(&luks->header.key_slots[i].stripes);
1289     }
1290
1291     if (local_err) {
1292         error_propagate(errp, local_err);
1293         goto error;
1294     }
1295
1296     /* Write out the master key material, starting at the
1297      * sector immediately following the partition header. */
1298     if (writefunc(block,
1299                   luks->header.key_slots[0].key_offset *
1300                   QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1301                   splitkey, splitkeylen,
1302                   opaque,
1303                   errp) != splitkeylen) {
1304         goto error;
1305     }
1306
1307     luks->cipher_alg = luks_opts.cipher_alg;
1308     luks->cipher_mode = luks_opts.cipher_mode;
1309     luks->ivgen_alg = luks_opts.ivgen_alg;
1310     luks->ivgen_hash_alg = luks_opts.ivgen_hash_alg;
1311     luks->hash_alg = luks_opts.hash_alg;
1312
1313     memset(masterkey, 0, luks->header.key_bytes);
1314     g_free(masterkey);
1315     memset(slotkey, 0, luks->header.key_bytes);
1316     g_free(slotkey);
1317     g_free(splitkey);
1318     g_free(password);
1319     g_free(cipher_mode_spec);
1320
1321     qcrypto_ivgen_free(ivgen);
1322     qcrypto_cipher_free(cipher);
1323
1324     return 0;
1325
1326  error:
1327     if (masterkey) {
1328         memset(masterkey, 0, luks->header.key_bytes);
1329     }
1330     g_free(masterkey);
1331     if (slotkey) {
1332         memset(slotkey, 0, luks->header.key_bytes);
1333     }
1334     g_free(slotkey);
1335     g_free(splitkey);
1336     g_free(password);
1337     g_free(cipher_mode_spec);
1338
1339     qcrypto_ivgen_free(ivgen);
1340     qcrypto_cipher_free(cipher);
1341
1342     qcrypto_block_free_cipher(block);
1343     qcrypto_ivgen_free(block->ivgen);
1344
1345     g_free(luks);
1346     return -1;
1347 }
1348
1349
1350 static int qcrypto_block_luks_get_info(QCryptoBlock *block,
1351                                        QCryptoBlockInfo *info,
1352                                        Error **errp)
1353 {
1354     QCryptoBlockLUKS *luks = block->opaque;
1355     QCryptoBlockInfoLUKSSlot *slot;
1356     QCryptoBlockInfoLUKSSlotList *slots = NULL, **prev = &info->u.luks.slots;
1357     size_t i;
1358
1359     info->u.luks.cipher_alg = luks->cipher_alg;
1360     info->u.luks.cipher_mode = luks->cipher_mode;
1361     info->u.luks.ivgen_alg = luks->ivgen_alg;
1362     if (info->u.luks.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1363         info->u.luks.has_ivgen_hash_alg = true;
1364         info->u.luks.ivgen_hash_alg = luks->ivgen_hash_alg;
1365     }
1366     info->u.luks.hash_alg = luks->hash_alg;
1367     info->u.luks.payload_offset = block->payload_offset;
1368     info->u.luks.master_key_iters = luks->header.master_key_iterations;
1369     info->u.luks.uuid = g_strndup((const char *)luks->header.uuid,
1370                                   sizeof(luks->header.uuid));
1371
1372     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1373         slots = g_new0(QCryptoBlockInfoLUKSSlotList, 1);
1374         *prev = slots;
1375
1376         slots->value = slot = g_new0(QCryptoBlockInfoLUKSSlot, 1);
1377         slot->active = luks->header.key_slots[i].active ==
1378             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
1379         slot->key_offset = luks->header.key_slots[i].key_offset
1380              * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1381         if (slot->active) {
1382             slot->has_iters = true;
1383             slot->iters = luks->header.key_slots[i].iterations;
1384             slot->has_stripes = true;
1385             slot->stripes = luks->header.key_slots[i].stripes;
1386         }
1387
1388         prev = &slots->next;
1389     }
1390
1391     return 0;
1392 }
1393
1394
1395 static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
1396 {
1397     g_free(block->opaque);
1398 }
1399
1400
1401 static int
1402 qcrypto_block_luks_decrypt(QCryptoBlock *block,
1403                            uint64_t offset,
1404                            uint8_t *buf,
1405                            size_t len,
1406                            Error **errp)
1407 {
1408     assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1409     assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1410     return qcrypto_block_decrypt_helper(block,
1411                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1412                                         offset, buf, len, errp);
1413 }
1414
1415
1416 static int
1417 qcrypto_block_luks_encrypt(QCryptoBlock *block,
1418                            uint64_t offset,
1419                            uint8_t *buf,
1420                            size_t len,
1421                            Error **errp)
1422 {
1423     assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1424     assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1425     return qcrypto_block_encrypt_helper(block,
1426                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1427                                         offset, buf, len, errp);
1428 }
1429
1430
1431 const QCryptoBlockDriver qcrypto_block_driver_luks = {
1432     .open = qcrypto_block_luks_open,
1433     .create = qcrypto_block_luks_create,
1434     .get_info = qcrypto_block_luks_get_info,
1435     .cleanup = qcrypto_block_luks_cleanup,
1436     .decrypt = qcrypto_block_luks_decrypt,
1437     .encrypt = qcrypto_block_luks_encrypt,
1438     .has_format = qcrypto_block_luks_has_format,
1439 };