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 "crypto/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 } QEMU_PACKED;
 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 } QEMU_PACKED;
 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_lookup[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 char *const *map,
 268                                           size_t maplen,
 269                                           const char *type,
 270                                           Error **errp)
 271 {
 272     size_t i;
 273     for (i = 0; i < maplen; i++) {
 274         if (g_str_equal(map[i], name)) {
 275             return i;
 276         }
 277     }
 278
 279     error_setg(errp, "%s %s not supported", type, name);
 280     return 0;
 281 }
 282
 283 #define qcrypto_block_luks_cipher_mode_lookup(name, errp)               \
 284     qcrypto_block_luks_name_lookup(name,                                \
 285                                    QCryptoCipherMode_lookup,            \
 286                                    QCRYPTO_CIPHER_MODE__MAX,            \
 287                                    "Cipher mode",                       \
 288                                    errp)
 289
 290 #define qcrypto_block_luks_hash_name_lookup(name, errp)                 \
 291     qcrypto_block_luks_name_lookup(name,                                \
 292                                    QCryptoHashAlgorithm_lookup,         \
 293                                    QCRYPTO_HASH_ALG__MAX,               \
 294                                    "Hash algorithm",                    \
 295                                    errp)
 296
 297 #define qcrypto_block_luks_ivgen_name_lookup(name, errp)                \
 298     qcrypto_block_luks_name_lookup(name,                                \
 299                                    QCryptoIVGenAlgorithm_lookup,        \
 300                                    QCRYPTO_IVGEN_ALG__MAX,              \
 301                                    "IV generator",                      \
 302                                    errp)
 303
 304
 305 static bool
 306 qcrypto_block_luks_has_format(const uint8_t *buf,
 307                               size_t buf_size)
 308 {
 309     const QCryptoBlockLUKSHeader *luks_header = (const void *)buf;
 310
 311     if (buf_size >= offsetof(QCryptoBlockLUKSHeader, cipher_name) &&
 312         memcmp(luks_header->magic, qcrypto_block_luks_magic,
 313                QCRYPTO_BLOCK_LUKS_MAGIC_LEN) == 0 &&
 314         be16_to_cpu(luks_header->version) == QCRYPTO_BLOCK_LUKS_VERSION) {
 315         return true;
 316     } else {
 317         return false;
 318     }
 319 }
 320
 321
 322 /**
 323  * Deal with a quirk of dm-crypt usage of ESSIV.
 324  *
 325  * When calculating ESSIV IVs, the cipher length used by ESSIV
 326  * may be different from the cipher length used for the block
 327  * encryption, becauses dm-crypt uses the hash digest length
 328  * as the key size. ie, if you have AES 128 as the block cipher
 329  * and SHA 256 as ESSIV hash, then ESSIV will use AES 256 as
 330  * the cipher since that gets a key length matching the digest
 331  * size, not AES 128 with truncated digest as might be imagined
 332  */
 333 static QCryptoCipherAlgorithm
 334 qcrypto_block_luks_essiv_cipher(QCryptoCipherAlgorithm cipher,
 335                                 QCryptoHashAlgorithm hash,
 336                                 Error **errp)
 337 {
 338     size_t digestlen = qcrypto_hash_digest_len(hash);
 339     size_t keylen = qcrypto_cipher_get_key_len(cipher);
 340     if (digestlen == keylen) {
 341         return cipher;
 342     }
 343
 344     switch (cipher) {
 345     case QCRYPTO_CIPHER_ALG_AES_128:
 346     case QCRYPTO_CIPHER_ALG_AES_192:
 347     case QCRYPTO_CIPHER_ALG_AES_256:
 348         if (digestlen == qcrypto_cipher_get_key_len(
 349                 QCRYPTO_CIPHER_ALG_AES_128)) {
 350             return QCRYPTO_CIPHER_ALG_AES_128;
 351         } else if (digestlen == qcrypto_cipher_get_key_len(
 352                        QCRYPTO_CIPHER_ALG_AES_192)) {
 353             return QCRYPTO_CIPHER_ALG_AES_192;
 354         } else if (digestlen == qcrypto_cipher_get_key_len(
 355                        QCRYPTO_CIPHER_ALG_AES_256)) {
 356             return QCRYPTO_CIPHER_ALG_AES_256;
 357         } else {
 358             error_setg(errp, "No AES cipher with key size %zu available",
 359                        digestlen);
 360             return 0;
 361         }
 362         break;
 363     case QCRYPTO_CIPHER_ALG_SERPENT_128:
 364     case QCRYPTO_CIPHER_ALG_SERPENT_192:
 365     case QCRYPTO_CIPHER_ALG_SERPENT_256:
 366         if (digestlen == qcrypto_cipher_get_key_len(
 367                 QCRYPTO_CIPHER_ALG_SERPENT_128)) {
 368             return QCRYPTO_CIPHER_ALG_SERPENT_128;
 369         } else if (digestlen == qcrypto_cipher_get_key_len(
 370                        QCRYPTO_CIPHER_ALG_SERPENT_192)) {
 371             return QCRYPTO_CIPHER_ALG_SERPENT_192;
 372         } else if (digestlen == qcrypto_cipher_get_key_len(
 373                        QCRYPTO_CIPHER_ALG_SERPENT_256)) {
 374             return QCRYPTO_CIPHER_ALG_SERPENT_256;
 375         } else {
 376             error_setg(errp, "No Serpent cipher with key size %zu available",
 377                        digestlen);
 378             return 0;
 379         }
 380         break;
 381     case QCRYPTO_CIPHER_ALG_TWOFISH_128:
 382     case QCRYPTO_CIPHER_ALG_TWOFISH_192:
 383     case QCRYPTO_CIPHER_ALG_TWOFISH_256:
 384         if (digestlen == qcrypto_cipher_get_key_len(
 385                 QCRYPTO_CIPHER_ALG_TWOFISH_128)) {
 386             return QCRYPTO_CIPHER_ALG_TWOFISH_128;
 387         } else if (digestlen == qcrypto_cipher_get_key_len(
 388                        QCRYPTO_CIPHER_ALG_TWOFISH_192)) {
 389             return QCRYPTO_CIPHER_ALG_TWOFISH_192;
 390         } else if (digestlen == qcrypto_cipher_get_key_len(
 391                        QCRYPTO_CIPHER_ALG_TWOFISH_256)) {
 392             return QCRYPTO_CIPHER_ALG_TWOFISH_256;
 393         } else {
 394             error_setg(errp, "No Twofish cipher with key size %zu available",
 395                        digestlen);
 396             return 0;
 397         }
 398         break;
 399     default:
 400         error_setg(errp, "Cipher %s not supported with essiv",
 401                    QCryptoCipherAlgorithm_lookup[cipher]);
 402         return 0;
 403     }
 404 }
 405
 406 /*
 407  * Given a key slot, and user password, this will attempt to unlock
 408  * the master encryption key from the key slot.
 409  *
 410  * Returns:
 411  *    0 if the key slot is disabled, or key could not be decrypted
 412  *      with the provided password
 413  *    1 if the key slot is enabled, and key decrypted successfully
 414  *      with the provided password
 415  *   -1 if a fatal error occurred loading the key
 416  */
 417 static int
 418 qcrypto_block_luks_load_key(QCryptoBlock *block,
 419                             QCryptoBlockLUKSKeySlot *slot,
 420                             const char *password,
 421                             QCryptoCipherAlgorithm cipheralg,
 422                             QCryptoCipherMode ciphermode,
 423                             QCryptoHashAlgorithm hash,
 424                             QCryptoIVGenAlgorithm ivalg,
 425                             QCryptoCipherAlgorithm ivcipheralg,
 426                             QCryptoHashAlgorithm ivhash,
 427                             uint8_t *masterkey,
 428                             size_t masterkeylen,
 429                             QCryptoBlockReadFunc readfunc,
 430                             void *opaque,
 431                             Error **errp)
 432 {
 433     QCryptoBlockLUKS *luks = block->opaque;
 434     uint8_t *splitkey;
 435     size_t splitkeylen;
 436     uint8_t *possiblekey;
 437     int ret = -1;
 438     ssize_t rv;
 439     QCryptoCipher *cipher = NULL;
 440     uint8_t keydigest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
 441     QCryptoIVGen *ivgen = NULL;
 442     size_t niv;
 443
 444     if (slot->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
 445         return 0;
 446     }
 447
 448     splitkeylen = masterkeylen * slot->stripes;
 449     splitkey = g_new0(uint8_t, splitkeylen);
 450     possiblekey = g_new0(uint8_t, masterkeylen);
 451
 452     /*
 453      * The user password is used to generate a (possible)
 454      * decryption key. This may or may not successfully
 455      * decrypt the master key - we just blindly assume
 456      * the key is correct and validate the results of
 457      * decryption later.
 458      */
 459     if (qcrypto_pbkdf2(hash,
 460                        (const uint8_t *)password, strlen(password),
 461                        slot->salt, QCRYPTO_BLOCK_LUKS_SALT_LEN,
 462                        slot->iterations,
 463                        possiblekey, masterkeylen,
 464                        errp) < 0) {
 465         goto cleanup;
 466     }
 467
 468     /*
 469      * We need to read the master key material from the
 470      * LUKS key material header. What we're reading is
 471      * not the raw master key, but rather the data after
 472      * it has been passed through AFSplit and the result
 473      * then encrypted.
 474      */
 475     rv = readfunc(block,
 476                   slot->key_offset * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 477                   splitkey, splitkeylen,
 478                   opaque,
 479                   errp);
 480     if (rv < 0) {
 481         goto cleanup;
 482     }
 483
 484
 485     /* Setup the cipher/ivgen that we'll use to try to decrypt
 486      * the split master key material */
 487     cipher = qcrypto_cipher_new(cipheralg, ciphermode,
 488                                 possiblekey, masterkeylen,
 489                                 errp);
 490     if (!cipher) {
 491         goto cleanup;
 492     }
 493
 494     niv = qcrypto_cipher_get_iv_len(cipheralg,
 495                                     ciphermode);
 496     ivgen = qcrypto_ivgen_new(ivalg,
 497                               ivcipheralg,
 498                               ivhash,
 499                               possiblekey, masterkeylen,
 500                               errp);
 501     if (!ivgen) {
 502         goto cleanup;
 503     }
 504
 505
 506     /*
 507      * The master key needs to be decrypted in the same
 508      * way that the block device payload will be decrypted
 509      * later. In particular we'll be using the IV generator
 510      * to reset the encryption cipher every time the master
 511      * key crosses a sector boundary.
 512      */
 513     if (qcrypto_block_decrypt_helper(cipher,
 514                                      niv,
 515                                      ivgen,
 516                                      QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 517                                      0,
 518                                      splitkey,
 519                                      splitkeylen,
 520                                      errp) < 0) {
 521         goto cleanup;
 522     }
 523
 524     /*
 525      * Now we've decrypted the split master key, join
 526      * it back together to get the actual master key.
 527      */
 528     if (qcrypto_afsplit_decode(hash,
 529                                masterkeylen,
 530                                slot->stripes,
 531                                splitkey,
 532                                masterkey,
 533                                errp) < 0) {
 534         goto cleanup;
 535     }
 536
 537
 538     /*
 539      * We still don't know that the masterkey we got is valid,
 540      * because we just blindly assumed the user's password
 541      * was correct. This is where we now verify it. We are
 542      * creating a hash of the master key using PBKDF and
 543      * then comparing that to the hash stored in the key slot
 544      * header
 545      */
 546     if (qcrypto_pbkdf2(hash,
 547                        masterkey, masterkeylen,
 548                        luks->header.master_key_salt,
 549                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
 550                        luks->header.master_key_iterations,
 551                        keydigest, G_N_ELEMENTS(keydigest),
 552                        errp) < 0) {
 553         goto cleanup;
 554     }
 555
 556     if (memcmp(keydigest, luks->header.master_key_digest,
 557                QCRYPTO_BLOCK_LUKS_DIGEST_LEN) == 0) {
 558         /* Success, we got the right master key */
 559         ret = 1;
 560         goto cleanup;
 561     }
 562
 563     /* Fail, user's password was not valid for this key slot,
 564      * tell caller to try another slot */
 565     ret = 0;
 566
 567  cleanup:
 568     qcrypto_ivgen_free(ivgen);
 569     qcrypto_cipher_free(cipher);
 570     g_free(splitkey);
 571     g_free(possiblekey);
 572     return ret;
 573 }
 574
 575
 576 /*
 577  * Given a user password, this will iterate over all key
 578  * slots and try to unlock each active key slot using the
 579  * password until it successfully obtains a master key.
 580  *
 581  * Returns 0 if a key was loaded, -1 if no keys could be loaded
 582  */
 583 static int
 584 qcrypto_block_luks_find_key(QCryptoBlock *block,
 585                             const char *password,
 586                             QCryptoCipherAlgorithm cipheralg,
 587                             QCryptoCipherMode ciphermode,
 588                             QCryptoHashAlgorithm hash,
 589                             QCryptoIVGenAlgorithm ivalg,
 590                             QCryptoCipherAlgorithm ivcipheralg,
 591                             QCryptoHashAlgorithm ivhash,
 592                             uint8_t **masterkey,
 593                             size_t *masterkeylen,
 594                             QCryptoBlockReadFunc readfunc,
 595                             void *opaque,
 596                             Error **errp)
 597 {
 598     QCryptoBlockLUKS *luks = block->opaque;
 599     size_t i;
 600     int rv;
 601
 602     *masterkey = g_new0(uint8_t, luks->header.key_bytes);
 603     *masterkeylen = luks->header.key_bytes;
 604
 605     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
 606         rv = qcrypto_block_luks_load_key(block,
 607                                          &luks->header.key_slots[i],
 608                                          password,
 609                                          cipheralg,
 610                                          ciphermode,
 611                                          hash,
 612                                          ivalg,
 613                                          ivcipheralg,
 614                                          ivhash,
 615                                          *masterkey,
 616                                          *masterkeylen,
 617                                          readfunc,
 618                                          opaque,
 619                                          errp);
 620         if (rv < 0) {
 621             goto error;
 622         }
 623         if (rv == 1) {
 624             return 0;
 625         }
 626     }
 627
 628     error_setg(errp, "Invalid password, cannot unlock any keyslot");
 629
 630  error:
 631     g_free(*masterkey);
 632     *masterkey = NULL;
 633     *masterkeylen = 0;
 634     return -1;
 635 }
 636
 637
 638 static int
 639 qcrypto_block_luks_open(QCryptoBlock *block,
 640                         QCryptoBlockOpenOptions *options,
 641                         const char *optprefix,
 642                         QCryptoBlockReadFunc readfunc,
 643                         void *opaque,
 644                         unsigned int flags,
 645                         Error **errp)
 646 {
 647     QCryptoBlockLUKS *luks;
 648     Error *local_err = NULL;
 649     int ret = 0;
 650     size_t i;
 651     ssize_t rv;
 652     uint8_t *masterkey = NULL;
 653     size_t masterkeylen;
 654     char *ivgen_name, *ivhash_name;
 655     QCryptoCipherMode ciphermode;
 656     QCryptoCipherAlgorithm cipheralg;
 657     QCryptoIVGenAlgorithm ivalg;
 658     QCryptoCipherAlgorithm ivcipheralg;
 659     QCryptoHashAlgorithm hash;
 660     QCryptoHashAlgorithm ivhash;
 661     char *password = NULL;
 662
 663     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
 664         if (!options->u.luks.key_secret) {
 665             error_setg(errp, "Parameter '%skey-secret' is required for cipher",
 666                        optprefix ? optprefix : "");
 667             return -1;
 668         }
 669         password = qcrypto_secret_lookup_as_utf8(
 670             options->u.luks.key_secret, errp);
 671         if (!password) {
 672             return -1;
 673         }
 674     }
 675
 676     luks = g_new0(QCryptoBlockLUKS, 1);
 677     block->opaque = luks;
 678
 679     /* Read the entire LUKS header, minus the key material from
 680      * the underlying device */
 681     rv = readfunc(block, 0,
 682                   (uint8_t *)&luks->header,
 683                   sizeof(luks->header),
 684                   opaque,
 685                   errp);
 686     if (rv < 0) {
 687         ret = rv;
 688         goto fail;
 689     }
 690
 691     /* The header is always stored in big-endian format, so
 692      * convert everything to native */
 693     be16_to_cpus(&luks->header.version);
 694     be32_to_cpus(&luks->header.payload_offset);
 695     be32_to_cpus(&luks->header.key_bytes);
 696     be32_to_cpus(&luks->header.master_key_iterations);
 697
 698     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
 699         be32_to_cpus(&luks->header.key_slots[i].active);
 700         be32_to_cpus(&luks->header.key_slots[i].iterations);
 701         be32_to_cpus(&luks->header.key_slots[i].key_offset);
 702         be32_to_cpus(&luks->header.key_slots[i].stripes);
 703     }
 704
 705     if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
 706                QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
 707         error_setg(errp, "Volume is not in LUKS format");
 708         ret = -EINVAL;
 709         goto fail;
 710     }
 711     if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
 712         error_setg(errp, "LUKS version %" PRIu32 " is not supported",
 713                    luks->header.version);
 714         ret = -ENOTSUP;
 715         goto fail;
 716     }
 717
 718     /*
 719      * The cipher_mode header contains a string that we have
 720      * to further parse, of the format
 721      *
 722      *    <cipher-mode>-<iv-generator>[:<iv-hash>]
 723      *
 724      * eg  cbc-essiv:sha256, cbc-plain64
 725      */
 726     ivgen_name = strchr(luks->header.cipher_mode, '-');
 727     if (!ivgen_name) {
 728         ret = -EINVAL;
 729         error_setg(errp, "Unexpected cipher mode string format %s",
 730                    luks->header.cipher_mode);
 731         goto fail;
 732     }
 733     *ivgen_name = '\0';
 734     ivgen_name++;
 735
 736     ivhash_name = strchr(ivgen_name, ':');
 737     if (!ivhash_name) {
 738         ivhash = 0;
 739     } else {
 740         *ivhash_name = '\0';
 741         ivhash_name++;
 742
 743         ivhash = qcrypto_block_luks_hash_name_lookup(ivhash_name,
 744                                                      &local_err);
 745         if (local_err) {
 746             ret = -ENOTSUP;
 747             error_propagate(errp, local_err);
 748             goto fail;
 749         }
 750     }
 751
 752     ciphermode = qcrypto_block_luks_cipher_mode_lookup(luks->header.cipher_mode,
 753                                                        &local_err);
 754     if (local_err) {
 755         ret = -ENOTSUP;
 756         error_propagate(errp, local_err);
 757         goto fail;
 758     }
 759
 760     cipheralg = qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
 761                                                       ciphermode,
 762                                                       luks->header.key_bytes,
 763                                                       &local_err);
 764     if (local_err) {
 765         ret = -ENOTSUP;
 766         error_propagate(errp, local_err);
 767         goto fail;
 768     }
 769
 770     hash = qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
 771                                                &local_err);
 772     if (local_err) {
 773         ret = -ENOTSUP;
 774         error_propagate(errp, local_err);
 775         goto fail;
 776     }
 777
 778     ivalg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
 779                                                  &local_err);
 780     if (local_err) {
 781         ret = -ENOTSUP;
 782         error_propagate(errp, local_err);
 783         goto fail;
 784     }
 785
 786     if (ivalg == QCRYPTO_IVGEN_ALG_ESSIV) {
 787         if (!ivhash_name) {
 788             ret = -EINVAL;
 789             error_setg(errp, "Missing IV generator hash specification");
 790             goto fail;
 791         }
 792         ivcipheralg = qcrypto_block_luks_essiv_cipher(cipheralg,
 793                                                       ivhash,
 794                                                       &local_err);
 795         if (local_err) {
 796             ret = -ENOTSUP;
 797             error_propagate(errp, local_err);
 798             goto fail;
 799         }
 800     } else {
 801         /* Note we parsed the ivhash_name earlier in the cipher_mode
 802          * spec string even with plain/plain64 ivgens, but we
 803          * will ignore it, since it is irrelevant for these ivgens.
 804          * This is for compat with dm-crypt which will silently
 805          * ignore hash names with these ivgens rather than report
 806          * an error about the invalid usage
 807          */
 808         ivcipheralg = cipheralg;
 809     }
 810
 811     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
 812         /* Try to find which key slot our password is valid for
 813          * and unlock the master key from that slot.
 814          */
 815         if (qcrypto_block_luks_find_key(block,
 816                                         password,
 817                                         cipheralg, ciphermode,
 818                                         hash,
 819                                         ivalg,
 820                                         ivcipheralg,
 821                                         ivhash,
 822                                         &masterkey, &masterkeylen,
 823                                         readfunc, opaque,
 824                                         errp) < 0) {
 825             ret = -EACCES;
 826             goto fail;
 827         }
 828
 829         /* We have a valid master key now, so can setup the
 830          * block device payload decryption objects
 831          */
 832         block->kdfhash = hash;
 833         block->niv = qcrypto_cipher_get_iv_len(cipheralg,
 834                                                ciphermode);
 835         block->ivgen = qcrypto_ivgen_new(ivalg,
 836                                          ivcipheralg,
 837                                          ivhash,
 838                                          masterkey, masterkeylen,
 839                                          errp);
 840         if (!block->ivgen) {
 841             ret = -ENOTSUP;
 842             goto fail;
 843         }
 844
 845         block->cipher = qcrypto_cipher_new(cipheralg,
 846                                            ciphermode,
 847                                            masterkey, masterkeylen,
 848                                            errp);
 849         if (!block->cipher) {
 850             ret = -ENOTSUP;
 851             goto fail;
 852         }
 853     }
 854
 855     block->payload_offset = luks->header.payload_offset *
 856         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
 857
 858     luks->cipher_alg = cipheralg;
 859     luks->cipher_mode = ciphermode;
 860     luks->ivgen_alg = ivalg;
 861     luks->ivgen_hash_alg = ivhash;
 862     luks->hash_alg = hash;
 863
 864     g_free(masterkey);
 865     g_free(password);
 866
 867     return 0;
 868
 869  fail:
 870     g_free(masterkey);
 871     qcrypto_cipher_free(block->cipher);
 872     qcrypto_ivgen_free(block->ivgen);
 873     g_free(luks);
 874     g_free(password);
 875     return ret;
 876 }
 877
 878
 879 static void
 880 qcrypto_block_luks_uuid_gen(uint8_t *uuidstr)
 881 {
 882     QemuUUID uuid;
 883     qemu_uuid_generate(&uuid);
 884     qemu_uuid_unparse(&uuid, (char *)uuidstr);
 885 }
 886
 887 static int
 888 qcrypto_block_luks_create(QCryptoBlock *block,
 889                           QCryptoBlockCreateOptions *options,
 890                           const char *optprefix,
 891                           QCryptoBlockInitFunc initfunc,
 892                           QCryptoBlockWriteFunc writefunc,
 893                           void *opaque,
 894                           Error **errp)
 895 {
 896     QCryptoBlockLUKS *luks;
 897     QCryptoBlockCreateOptionsLUKS luks_opts;
 898     Error *local_err = NULL;
 899     uint8_t *masterkey = NULL;
 900     uint8_t *slotkey = NULL;
 901     uint8_t *splitkey = NULL;
 902     size_t splitkeylen = 0;
 903     size_t i;
 904     QCryptoCipher *cipher = NULL;
 905     QCryptoIVGen *ivgen = NULL;
 906     char *password;
 907     const char *cipher_alg;
 908     const char *cipher_mode;
 909     const char *ivgen_alg;
 910     const char *ivgen_hash_alg = NULL;
 911     const char *hash_alg;
 912     char *cipher_mode_spec = NULL;
 913     QCryptoCipherAlgorithm ivcipheralg = 0;
 914     uint64_t iters;
 915
 916     memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
 917     if (!luks_opts.has_iter_time) {
 918         luks_opts.iter_time = 2000;
 919     }
 920     if (!luks_opts.has_cipher_alg) {
 921         luks_opts.cipher_alg = QCRYPTO_CIPHER_ALG_AES_256;
 922     }
 923     if (!luks_opts.has_cipher_mode) {
 924         luks_opts.cipher_mode = QCRYPTO_CIPHER_MODE_XTS;
 925     }
 926     if (!luks_opts.has_ivgen_alg) {
 927         luks_opts.ivgen_alg = QCRYPTO_IVGEN_ALG_PLAIN64;
 928     }
 929     if (!luks_opts.has_hash_alg) {
 930         luks_opts.hash_alg = QCRYPTO_HASH_ALG_SHA256;
 931     }
 932     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
 933         if (!luks_opts.has_ivgen_hash_alg) {
 934             luks_opts.ivgen_hash_alg = QCRYPTO_HASH_ALG_SHA256;
 935             luks_opts.has_ivgen_hash_alg = true;
 936         }
 937     }
 938     /* Note we're allowing ivgen_hash_alg to be set even for
 939      * non-essiv iv generators that don't need a hash. It will
 940      * be silently ignored, for compatibility with dm-crypt */
 941
 942     if (!options->u.luks.key_secret) {
 943         error_setg(errp, "Parameter '%skey-secret' is required for cipher",
 944                    optprefix ? optprefix : "");
 945         return -1;
 946     }
 947     password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret, errp);
 948     if (!password) {
 949         return -1;
 950     }
 951
 952     luks = g_new0(QCryptoBlockLUKS, 1);
 953     block->opaque = luks;
 954
 955     memcpy(luks->header.magic, qcrypto_block_luks_magic,
 956            QCRYPTO_BLOCK_LUKS_MAGIC_LEN);
 957
 958     /* We populate the header in native endianness initially and
 959      * then convert everything to big endian just before writing
 960      * it out to disk
 961      */
 962     luks->header.version = QCRYPTO_BLOCK_LUKS_VERSION;
 963     qcrypto_block_luks_uuid_gen(luks->header.uuid);
 964
 965     cipher_alg = qcrypto_block_luks_cipher_alg_lookup(luks_opts.cipher_alg,
 966                                                       errp);
 967     if (!cipher_alg) {
 968         goto error;
 969     }
 970
 971     cipher_mode = QCryptoCipherMode_lookup[luks_opts.cipher_mode];
 972     ivgen_alg = QCryptoIVGenAlgorithm_lookup[luks_opts.ivgen_alg];
 973     if (luks_opts.has_ivgen_hash_alg) {
 974         ivgen_hash_alg = QCryptoHashAlgorithm_lookup[luks_opts.ivgen_hash_alg];
 975         cipher_mode_spec = g_strdup_printf("%s-%s:%s", cipher_mode, ivgen_alg,
 976                                            ivgen_hash_alg);
 977     } else {
 978         cipher_mode_spec = g_strdup_printf("%s-%s", cipher_mode, ivgen_alg);
 979     }
 980     hash_alg = QCryptoHashAlgorithm_lookup[luks_opts.hash_alg];
 981
 982
 983     if (strlen(cipher_alg) >= QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN) {
 984         error_setg(errp, "Cipher name '%s' is too long for LUKS header",
 985                    cipher_alg);
 986         goto error;
 987     }
 988     if (strlen(cipher_mode_spec) >= QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN) {
 989         error_setg(errp, "Cipher mode '%s' is too long for LUKS header",
 990                    cipher_mode_spec);
 991         goto error;
 992     }
 993     if (strlen(hash_alg) >= QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN) {
 994         error_setg(errp, "Hash name '%s' is too long for LUKS header",
 995                    hash_alg);
 996         goto error;
 997     }
 998
 999     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1000         ivcipheralg = qcrypto_block_luks_essiv_cipher(luks_opts.cipher_alg,
1001                                                       luks_opts.ivgen_hash_alg,
1002                                                       &local_err);
1003         if (local_err) {
1004             error_propagate(errp, local_err);
1005             goto error;
1006         }
1007     } else {
1008         ivcipheralg = luks_opts.cipher_alg;
1009     }
1010
1011     strcpy(luks->header.cipher_name, cipher_alg);
1012     strcpy(luks->header.cipher_mode, cipher_mode_spec);
1013     strcpy(luks->header.hash_spec, hash_alg);
1014
1015     luks->header.key_bytes = qcrypto_cipher_get_key_len(luks_opts.cipher_alg);
1016     if (luks_opts.cipher_mode == QCRYPTO_CIPHER_MODE_XTS) {
1017         luks->header.key_bytes *= 2;
1018     }
1019
1020     /* Generate the salt used for hashing the master key
1021      * with PBKDF later
1022      */
1023     if (qcrypto_random_bytes(luks->header.master_key_salt,
1024                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1025                              errp) < 0) {
1026         goto error;
1027     }
1028
1029     /* Generate random master key */
1030     masterkey = g_new0(uint8_t, luks->header.key_bytes);
1031     if (qcrypto_random_bytes(masterkey,
1032                              luks->header.key_bytes, errp) < 0) {
1033         goto error;
1034     }
1035
1036
1037     /* Setup the block device payload encryption objects */
1038     block->cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
1039                                        luks_opts.cipher_mode,
1040                                        masterkey, luks->header.key_bytes,
1041                                        errp);
1042     if (!block->cipher) {
1043         goto error;
1044     }
1045
1046     block->kdfhash = luks_opts.hash_alg;
1047     block->niv = qcrypto_cipher_get_iv_len(luks_opts.cipher_alg,
1048                                            luks_opts.cipher_mode);
1049     block->ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1050                                      ivcipheralg,
1051                                      luks_opts.ivgen_hash_alg,
1052                                      masterkey, luks->header.key_bytes,
1053                                      errp);
1054
1055     if (!block->ivgen) {
1056         goto error;
1057     }
1058
1059
1060     /* Determine how many iterations we need to hash the master
1061      * key, in order to have 1 second of compute time used
1062      */
1063     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1064                                        masterkey, luks->header.key_bytes,
1065                                        luks->header.master_key_salt,
1066                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1067                                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1068                                        &local_err);
1069     if (local_err) {
1070         error_propagate(errp, local_err);
1071         goto error;
1072     }
1073
1074     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1075         error_setg_errno(errp, ERANGE,
1076                          "PBKDF iterations %llu too large to scale",
1077                          (unsigned long long)iters);
1078         goto error;
1079     }
1080
1081     /* iter_time was in millis, but count_iters reported for secs */
1082     iters = iters * luks_opts.iter_time / 1000;
1083
1084     /* Why /= 8 ?  That matches cryptsetup, but there's no
1085      * explanation why they chose /= 8... Probably so that
1086      * if all 8 keyslots are active we only spend 1 second
1087      * in total time to check all keys */
1088     iters /= 8;
1089     if (iters > UINT32_MAX) {
1090         error_setg_errno(errp, ERANGE,
1091                          "PBKDF iterations %llu larger than %u",
1092                          (unsigned long long)iters, UINT32_MAX);
1093         goto error;
1094     }
1095     iters = MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS);
1096     luks->header.master_key_iterations = iters;
1097
1098     /* Hash the master key, saving the result in the LUKS
1099      * header. This hash is used when opening the encrypted
1100      * device to verify that the user password unlocked a
1101      * valid master key
1102      */
1103     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1104                        masterkey, luks->header.key_bytes,
1105                        luks->header.master_key_salt,
1106                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1107                        luks->header.master_key_iterations,
1108                        luks->header.master_key_digest,
1109                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1110                        errp) < 0) {
1111         goto error;
1112     }
1113
1114
1115     /* Although LUKS has multiple key slots, we're just going
1116      * to use the first key slot */
1117     splitkeylen = luks->header.key_bytes * QCRYPTO_BLOCK_LUKS_STRIPES;
1118     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1119         luks->header.key_slots[i].active = i == 0 ?
1120             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED :
1121             QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
1122         luks->header.key_slots[i].stripes = QCRYPTO_BLOCK_LUKS_STRIPES;
1123
1124         /* This calculation doesn't match that shown in the spec,
1125          * but instead follows the cryptsetup implementation.
1126          */
1127         luks->header.key_slots[i].key_offset =
1128             (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1129              QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1130             (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1131                       (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1132                        QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) * i);
1133     }
1134
1135     if (qcrypto_random_bytes(luks->header.key_slots[0].salt,
1136                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1137                              errp) < 0) {
1138         goto error;
1139     }
1140
1141     /* Again we determine how many iterations are required to
1142      * hash the user password while consuming 1 second of compute
1143      * time */
1144     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1145                                        (uint8_t *)password, strlen(password),
1146                                        luks->header.key_slots[0].salt,
1147                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1148                                        luks->header.key_bytes,
1149                                        &local_err);
1150     if (local_err) {
1151         error_propagate(errp, local_err);
1152         goto error;
1153     }
1154
1155     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1156         error_setg_errno(errp, ERANGE,
1157                          "PBKDF iterations %llu too large to scale",
1158                          (unsigned long long)iters);
1159         goto error;
1160     }
1161
1162     /* iter_time was in millis, but count_iters reported for secs */
1163     iters = iters * luks_opts.iter_time / 1000;
1164
1165     if (iters > UINT32_MAX) {
1166         error_setg_errno(errp, ERANGE,
1167                          "PBKDF iterations %llu larger than %u",
1168                          (unsigned long long)iters, UINT32_MAX);
1169         goto error;
1170     }
1171
1172     luks->header.key_slots[0].iterations =
1173         MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);
1174
1175
1176     /* Generate a key that we'll use to encrypt the master
1177      * key, from the user's password
1178      */
1179     slotkey = g_new0(uint8_t, luks->header.key_bytes);
1180     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1181                        (uint8_t *)password, strlen(password),
1182                        luks->header.key_slots[0].salt,
1183                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1184                        luks->header.key_slots[0].iterations,
1185                        slotkey, luks->header.key_bytes,
1186                        errp) < 0) {
1187         goto error;
1188     }
1189
1190
1191     /* Setup the encryption objects needed to encrypt the
1192      * master key material
1193      */
1194     cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
1195                                 luks_opts.cipher_mode,
1196                                 slotkey, luks->header.key_bytes,
1197                                 errp);
1198     if (!cipher) {
1199         goto error;
1200     }
1201
1202     ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1203                               ivcipheralg,
1204                               luks_opts.ivgen_hash_alg,
1205                               slotkey, luks->header.key_bytes,
1206                               errp);
1207     if (!ivgen) {
1208         goto error;
1209     }
1210
1211     /* Before storing the master key, we need to vastly
1212      * increase its size, as protection against forensic
1213      * disk data recovery */
1214     splitkey = g_new0(uint8_t, splitkeylen);
1215
1216     if (qcrypto_afsplit_encode(luks_opts.hash_alg,
1217                                luks->header.key_bytes,
1218                                luks->header.key_slots[0].stripes,
1219                                masterkey,
1220                                splitkey,
1221                                errp) < 0) {
1222         goto error;
1223     }
1224
1225     /* Now we encrypt the split master key with the key generated
1226      * from the user's password, before storing it */
1227     if (qcrypto_block_encrypt_helper(cipher, block->niv, ivgen,
1228                                      QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1229                                      0,
1230                                      splitkey,
1231                                      splitkeylen,
1232                                      errp) < 0) {
1233         goto error;
1234     }
1235
1236
1237     /* The total size of the LUKS headers is the partition header + key
1238      * slot headers, rounded up to the nearest sector, combined with
1239      * the size of each master key material region, also rounded up
1240      * to the nearest sector */
1241     luks->header.payload_offset =
1242         (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1243          QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1244         (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1245                   (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1246                    QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) *
1247          QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
1248
1249     block->payload_offset = luks->header.payload_offset *
1250         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1251
1252     /* Reserve header space to match payload offset */
1253     initfunc(block, block->payload_offset, opaque, &local_err);
1254     if (local_err) {
1255         error_propagate(errp, local_err);
1256         goto error;
1257     }
1258
1259     /* Everything on disk uses Big Endian, so flip header fields
1260      * before writing them */
1261     cpu_to_be16s(&luks->header.version);
1262     cpu_to_be32s(&luks->header.payload_offset);
1263     cpu_to_be32s(&luks->header.key_bytes);
1264     cpu_to_be32s(&luks->header.master_key_iterations);
1265
1266     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1267         cpu_to_be32s(&luks->header.key_slots[i].active);
1268         cpu_to_be32s(&luks->header.key_slots[i].iterations);
1269         cpu_to_be32s(&luks->header.key_slots[i].key_offset);
1270         cpu_to_be32s(&luks->header.key_slots[i].stripes);
1271     }
1272
1273
1274     /* Write out the partition header and key slot headers */
1275     writefunc(block, 0,
1276               (const uint8_t *)&luks->header,
1277               sizeof(luks->header),
1278               opaque,
1279               &local_err);
1280
1281     /* Delay checking local_err until we've byte-swapped */
1282
1283     /* Byte swap the header back to native, in case we need
1284      * to read it again later */
1285     be16_to_cpus(&luks->header.version);
1286     be32_to_cpus(&luks->header.payload_offset);
1287     be32_to_cpus(&luks->header.key_bytes);
1288     be32_to_cpus(&luks->header.master_key_iterations);
1289
1290     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1291         be32_to_cpus(&luks->header.key_slots[i].active);
1292         be32_to_cpus(&luks->header.key_slots[i].iterations);
1293         be32_to_cpus(&luks->header.key_slots[i].key_offset);
1294         be32_to_cpus(&luks->header.key_slots[i].stripes);
1295     }
1296
1297     if (local_err) {
1298         error_propagate(errp, local_err);
1299         goto error;
1300     }
1301
1302     /* Write out the master key material, starting at the
1303      * sector immediately following the partition header. */
1304     if (writefunc(block,
1305                   luks->header.key_slots[0].key_offset *
1306                   QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1307                   splitkey, splitkeylen,
1308                   opaque,
1309                   errp) != splitkeylen) {
1310         goto error;
1311     }
1312
1313     luks->cipher_alg = luks_opts.cipher_alg;
1314     luks->cipher_mode = luks_opts.cipher_mode;
1315     luks->ivgen_alg = luks_opts.ivgen_alg;
1316     luks->ivgen_hash_alg = luks_opts.ivgen_hash_alg;
1317     luks->hash_alg = luks_opts.hash_alg;
1318
1319     memset(masterkey, 0, luks->header.key_bytes);
1320     g_free(masterkey);
1321     memset(slotkey, 0, luks->header.key_bytes);
1322     g_free(slotkey);
1323     g_free(splitkey);
1324     g_free(password);
1325     g_free(cipher_mode_spec);
1326
1327     qcrypto_ivgen_free(ivgen);
1328     qcrypto_cipher_free(cipher);
1329
1330     return 0;
1331
1332  error:
1333     if (masterkey) {
1334         memset(masterkey, 0, luks->header.key_bytes);
1335     }
1336     g_free(masterkey);
1337     if (slotkey) {
1338         memset(slotkey, 0, luks->header.key_bytes);
1339     }
1340     g_free(slotkey);
1341     g_free(splitkey);
1342     g_free(password);
1343     g_free(cipher_mode_spec);
1344
1345     qcrypto_ivgen_free(ivgen);
1346     qcrypto_cipher_free(cipher);
1347
1348     g_free(luks);
1349     return -1;
1350 }
1351
1352
1353 static int qcrypto_block_luks_get_info(QCryptoBlock *block,
1354                                        QCryptoBlockInfo *info,
1355                                        Error **errp)
1356 {
1357     QCryptoBlockLUKS *luks = block->opaque;
1358     QCryptoBlockInfoLUKSSlot *slot;
1359     QCryptoBlockInfoLUKSSlotList *slots = NULL, **prev = &info->u.luks.slots;
1360     size_t i;
1361
1362     info->u.luks.cipher_alg = luks->cipher_alg;
1363     info->u.luks.cipher_mode = luks->cipher_mode;
1364     info->u.luks.ivgen_alg = luks->ivgen_alg;
1365     if (info->u.luks.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1366         info->u.luks.has_ivgen_hash_alg = true;
1367         info->u.luks.ivgen_hash_alg = luks->ivgen_hash_alg;
1368     }
1369     info->u.luks.hash_alg = luks->hash_alg;
1370     info->u.luks.payload_offset = block->payload_offset;
1371     info->u.luks.master_key_iters = luks->header.master_key_iterations;
1372     info->u.luks.uuid = g_strndup((const char *)luks->header.uuid,
1373                                   sizeof(luks->header.uuid));
1374
1375     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1376         slots = g_new0(QCryptoBlockInfoLUKSSlotList, 1);
1377         *prev = slots;
1378
1379         slots->value = slot = g_new0(QCryptoBlockInfoLUKSSlot, 1);
1380         slot->active = luks->header.key_slots[i].active ==
1381             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
1382         slot->key_offset = luks->header.key_slots[i].key_offset
1383              * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1384         if (slot->active) {
1385             slot->has_iters = true;
1386             slot->iters = luks->header.key_slots[i].iterations;
1387             slot->has_stripes = true;
1388             slot->stripes = luks->header.key_slots[i].stripes;
1389         }
1390
1391         prev = &slots->next;
1392     }
1393
1394     return 0;
1395 }
1396
1397
1398 static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
1399 {
1400     g_free(block->opaque);
1401 }
1402
1403
1404 static int
1405 qcrypto_block_luks_decrypt(QCryptoBlock *block,
1406                            uint64_t startsector,
1407                            uint8_t *buf,
1408                            size_t len,
1409                            Error **errp)
1410 {
1411     return qcrypto_block_decrypt_helper(block->cipher,
1412                                         block->niv, block->ivgen,
1413                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1414                                         startsector, buf, len, errp);
1415 }
1416
1417
1418 static int
1419 qcrypto_block_luks_encrypt(QCryptoBlock *block,
1420                            uint64_t startsector,
1421                            uint8_t *buf,
1422                            size_t len,
1423                            Error **errp)
1424 {
1425     return qcrypto_block_encrypt_helper(block->cipher,
1426                                         block->niv, block->ivgen,
1427                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1428                                         startsector, buf, len, errp);
1429 }
1430
1431
1432 const QCryptoBlockDriver qcrypto_block_driver_luks = {
1433     .open = qcrypto_block_luks_open,
1434     .create = qcrypto_block_luks_create,
1435     .get_info = qcrypto_block_luks_get_info,
1436     .cleanup = qcrypto_block_luks_cleanup,
1437     .decrypt = qcrypto_block_luks_decrypt,
1438     .encrypt = qcrypto_block_luks_encrypt,
1439     .has_format = qcrypto_block_luks_has_format,
1440 };