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                   opaque,
 477                   slot->key_offset * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 478                   splitkey, splitkeylen,
 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                         QCryptoBlockReadFunc readfunc,
 642                         void *opaque,
 643                         unsigned int flags,
 644                         Error **errp)
 645 {
 646     QCryptoBlockLUKS *luks;
 647     Error *local_err = NULL;
 648     int ret = 0;
 649     size_t i;
 650     ssize_t rv;
 651     uint8_t *masterkey = NULL;
 652     size_t masterkeylen;
 653     char *ivgen_name, *ivhash_name;
 654     QCryptoCipherMode ciphermode;
 655     QCryptoCipherAlgorithm cipheralg;
 656     QCryptoIVGenAlgorithm ivalg;
 657     QCryptoCipherAlgorithm ivcipheralg;
 658     QCryptoHashAlgorithm hash;
 659     QCryptoHashAlgorithm ivhash;
 660     char *password = NULL;
 661
 662     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
 663         if (!options->u.luks.key_secret) {
 664             error_setg(errp, "Parameter 'key-secret' is required for cipher");
 665             return -1;
 666         }
 667         password = qcrypto_secret_lookup_as_utf8(
 668             options->u.luks.key_secret, errp);
 669         if (!password) {
 670             return -1;
 671         }
 672     }
 673
 674     luks = g_new0(QCryptoBlockLUKS, 1);
 675     block->opaque = luks;
 676
 677     /* Read the entire LUKS header, minus the key material from
 678      * the underlying device */
 679     rv = readfunc(block, opaque, 0,
 680                   (uint8_t *)&luks->header,
 681                   sizeof(luks->header),
 682                   errp);
 683     if (rv < 0) {
 684         ret = rv;
 685         goto fail;
 686     }
 687
 688     /* The header is always stored in big-endian format, so
 689      * convert everything to native */
 690     be16_to_cpus(&luks->header.version);
 691     be32_to_cpus(&luks->header.payload_offset);
 692     be32_to_cpus(&luks->header.key_bytes);
 693     be32_to_cpus(&luks->header.master_key_iterations);
 694
 695     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
 696         be32_to_cpus(&luks->header.key_slots[i].active);
 697         be32_to_cpus(&luks->header.key_slots[i].iterations);
 698         be32_to_cpus(&luks->header.key_slots[i].key_offset);
 699         be32_to_cpus(&luks->header.key_slots[i].stripes);
 700     }
 701
 702     if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
 703                QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
 704         error_setg(errp, "Volume is not in LUKS format");
 705         ret = -EINVAL;
 706         goto fail;
 707     }
 708     if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
 709         error_setg(errp, "LUKS version %" PRIu32 " is not supported",
 710                    luks->header.version);
 711         ret = -ENOTSUP;
 712         goto fail;
 713     }
 714
 715     /*
 716      * The cipher_mode header contains a string that we have
 717      * to further parse, of the format
 718      *
 719      *    <cipher-mode>-<iv-generator>[:<iv-hash>]
 720      *
 721      * eg  cbc-essiv:sha256, cbc-plain64
 722      */
 723     ivgen_name = strchr(luks->header.cipher_mode, '-');
 724     if (!ivgen_name) {
 725         ret = -EINVAL;
 726         error_setg(errp, "Unexpected cipher mode string format %s",
 727                    luks->header.cipher_mode);
 728         goto fail;
 729     }
 730     *ivgen_name = '\0';
 731     ivgen_name++;
 732
 733     ivhash_name = strchr(ivgen_name, ':');
 734     if (!ivhash_name) {
 735         ivhash = 0;
 736     } else {
 737         *ivhash_name = '\0';
 738         ivhash_name++;
 739
 740         ivhash = qcrypto_block_luks_hash_name_lookup(ivhash_name,
 741                                                      &local_err);
 742         if (local_err) {
 743             ret = -ENOTSUP;
 744             error_propagate(errp, local_err);
 745             goto fail;
 746         }
 747     }
 748
 749     ciphermode = qcrypto_block_luks_cipher_mode_lookup(luks->header.cipher_mode,
 750                                                        &local_err);
 751     if (local_err) {
 752         ret = -ENOTSUP;
 753         error_propagate(errp, local_err);
 754         goto fail;
 755     }
 756
 757     cipheralg = qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
 758                                                       ciphermode,
 759                                                       luks->header.key_bytes,
 760                                                       &local_err);
 761     if (local_err) {
 762         ret = -ENOTSUP;
 763         error_propagate(errp, local_err);
 764         goto fail;
 765     }
 766
 767     hash = qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
 768                                                &local_err);
 769     if (local_err) {
 770         ret = -ENOTSUP;
 771         error_propagate(errp, local_err);
 772         goto fail;
 773     }
 774
 775     ivalg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
 776                                                  &local_err);
 777     if (local_err) {
 778         ret = -ENOTSUP;
 779         error_propagate(errp, local_err);
 780         goto fail;
 781     }
 782
 783     if (ivalg == QCRYPTO_IVGEN_ALG_ESSIV) {
 784         if (!ivhash_name) {
 785             ret = -EINVAL;
 786             error_setg(errp, "Missing IV generator hash specification");
 787             goto fail;
 788         }
 789         ivcipheralg = qcrypto_block_luks_essiv_cipher(cipheralg,
 790                                                       ivhash,
 791                                                       &local_err);
 792         if (local_err) {
 793             ret = -ENOTSUP;
 794             error_propagate(errp, local_err);
 795             goto fail;
 796         }
 797     } else {
 798         /* Note we parsed the ivhash_name earlier in the cipher_mode
 799          * spec string even with plain/plain64 ivgens, but we
 800          * will ignore it, since it is irrelevant for these ivgens.
 801          * This is for compat with dm-crypt which will silently
 802          * ignore hash names with these ivgens rather than report
 803          * an error about the invalid usage
 804          */
 805         ivcipheralg = cipheralg;
 806     }
 807
 808     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
 809         /* Try to find which key slot our password is valid for
 810          * and unlock the master key from that slot.
 811          */
 812         if (qcrypto_block_luks_find_key(block,
 813                                         password,
 814                                         cipheralg, ciphermode,
 815                                         hash,
 816                                         ivalg,
 817                                         ivcipheralg,
 818                                         ivhash,
 819                                         &masterkey, &masterkeylen,
 820                                         readfunc, opaque,
 821                                         errp) < 0) {
 822             ret = -EACCES;
 823             goto fail;
 824         }
 825
 826         /* We have a valid master key now, so can setup the
 827          * block device payload decryption objects
 828          */
 829         block->kdfhash = hash;
 830         block->niv = qcrypto_cipher_get_iv_len(cipheralg,
 831                                                ciphermode);
 832         block->ivgen = qcrypto_ivgen_new(ivalg,
 833                                          ivcipheralg,
 834                                          ivhash,
 835                                          masterkey, masterkeylen,
 836                                          errp);
 837         if (!block->ivgen) {
 838             ret = -ENOTSUP;
 839             goto fail;
 840         }
 841
 842         block->cipher = qcrypto_cipher_new(cipheralg,
 843                                            ciphermode,
 844                                            masterkey, masterkeylen,
 845                                            errp);
 846         if (!block->cipher) {
 847             ret = -ENOTSUP;
 848             goto fail;
 849         }
 850     }
 851
 852     block->payload_offset = luks->header.payload_offset *
 853         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
 854
 855     luks->cipher_alg = cipheralg;
 856     luks->cipher_mode = ciphermode;
 857     luks->ivgen_alg = ivalg;
 858     luks->ivgen_hash_alg = ivhash;
 859     luks->hash_alg = hash;
 860
 861     g_free(masterkey);
 862     g_free(password);
 863
 864     return 0;
 865
 866  fail:
 867     g_free(masterkey);
 868     qcrypto_cipher_free(block->cipher);
 869     qcrypto_ivgen_free(block->ivgen);
 870     g_free(luks);
 871     g_free(password);
 872     return ret;
 873 }
 874
 875
 876 static void
 877 qcrypto_block_luks_uuid_gen(uint8_t *uuidstr)
 878 {
 879     QemuUUID uuid;
 880     qemu_uuid_generate(&uuid);
 881     qemu_uuid_unparse(&uuid, (char *)uuidstr);
 882 }
 883
 884 static int
 885 qcrypto_block_luks_create(QCryptoBlock *block,
 886                           QCryptoBlockCreateOptions *options,
 887                           QCryptoBlockInitFunc initfunc,
 888                           QCryptoBlockWriteFunc writefunc,
 889                           void *opaque,
 890                           Error **errp)
 891 {
 892     QCryptoBlockLUKS *luks;
 893     QCryptoBlockCreateOptionsLUKS luks_opts;
 894     Error *local_err = NULL;
 895     uint8_t *masterkey = NULL;
 896     uint8_t *slotkey = NULL;
 897     uint8_t *splitkey = NULL;
 898     size_t splitkeylen = 0;
 899     size_t i;
 900     QCryptoCipher *cipher = NULL;
 901     QCryptoIVGen *ivgen = NULL;
 902     char *password;
 903     const char *cipher_alg;
 904     const char *cipher_mode;
 905     const char *ivgen_alg;
 906     const char *ivgen_hash_alg = NULL;
 907     const char *hash_alg;
 908     char *cipher_mode_spec = NULL;
 909     QCryptoCipherAlgorithm ivcipheralg = 0;
 910     uint64_t iters;
 911
 912     memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
 913     if (!luks_opts.has_iter_time) {
 914         luks_opts.iter_time = 2000;
 915     }
 916     if (!luks_opts.has_cipher_alg) {
 917         luks_opts.cipher_alg = QCRYPTO_CIPHER_ALG_AES_256;
 918     }
 919     if (!luks_opts.has_cipher_mode) {
 920         luks_opts.cipher_mode = QCRYPTO_CIPHER_MODE_XTS;
 921     }
 922     if (!luks_opts.has_ivgen_alg) {
 923         luks_opts.ivgen_alg = QCRYPTO_IVGEN_ALG_PLAIN64;
 924     }
 925     if (!luks_opts.has_hash_alg) {
 926         luks_opts.hash_alg = QCRYPTO_HASH_ALG_SHA256;
 927     }
 928     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
 929         if (!luks_opts.has_ivgen_hash_alg) {
 930             luks_opts.ivgen_hash_alg = QCRYPTO_HASH_ALG_SHA256;
 931             luks_opts.has_ivgen_hash_alg = true;
 932         }
 933     }
 934     /* Note we're allowing ivgen_hash_alg to be set even for
 935      * non-essiv iv generators that don't need a hash. It will
 936      * be silently ignored, for compatibility with dm-crypt */
 937
 938     if (!options->u.luks.key_secret) {
 939         error_setg(errp, "Parameter 'key-secret' is required for cipher");
 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_lookup[luks_opts.cipher_mode];
 967     ivgen_alg = QCryptoIVGenAlgorithm_lookup[luks_opts.ivgen_alg];
 968     if (luks_opts.has_ivgen_hash_alg) {
 969         ivgen_hash_alg = QCryptoHashAlgorithm_lookup[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_lookup[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     block->cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
1034                                        luks_opts.cipher_mode,
1035                                        masterkey, luks->header.key_bytes,
1036                                        errp);
1037     if (!block->cipher) {
1038         goto error;
1039     }
1040
1041     block->kdfhash = luks_opts.hash_alg;
1042     block->niv = qcrypto_cipher_get_iv_len(luks_opts.cipher_alg,
1043                                            luks_opts.cipher_mode);
1044     block->ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1045                                      ivcipheralg,
1046                                      luks_opts.ivgen_hash_alg,
1047                                      masterkey, luks->header.key_bytes,
1048                                      errp);
1049
1050     if (!block->ivgen) {
1051         goto error;
1052     }
1053
1054
1055     /* Determine how many iterations we need to hash the master
1056      * key, in order to have 1 second of compute time used
1057      */
1058     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1059                                        masterkey, luks->header.key_bytes,
1060                                        luks->header.master_key_salt,
1061                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1062                                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1063                                        &local_err);
1064     if (local_err) {
1065         error_propagate(errp, local_err);
1066         goto error;
1067     }
1068
1069     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1070         error_setg_errno(errp, ERANGE,
1071                          "PBKDF iterations %llu too large to scale",
1072                          (unsigned long long)iters);
1073         goto error;
1074     }
1075
1076     /* iter_time was in millis, but count_iters reported for secs */
1077     iters = iters * luks_opts.iter_time / 1000;
1078
1079     /* Why /= 8 ?  That matches cryptsetup, but there's no
1080      * explanation why they chose /= 8... Probably so that
1081      * if all 8 keyslots are active we only spend 1 second
1082      * in total time to check all keys */
1083     iters /= 8;
1084     if (iters > UINT32_MAX) {
1085         error_setg_errno(errp, ERANGE,
1086                          "PBKDF iterations %llu larger than %u",
1087                          (unsigned long long)iters, UINT32_MAX);
1088         goto error;
1089     }
1090     iters = MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS);
1091     luks->header.master_key_iterations = iters;
1092
1093     /* Hash the master key, saving the result in the LUKS
1094      * header. This hash is used when opening the encrypted
1095      * device to verify that the user password unlocked a
1096      * valid master key
1097      */
1098     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1099                        masterkey, luks->header.key_bytes,
1100                        luks->header.master_key_salt,
1101                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1102                        luks->header.master_key_iterations,
1103                        luks->header.master_key_digest,
1104                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1105                        errp) < 0) {
1106         goto error;
1107     }
1108
1109
1110     /* Although LUKS has multiple key slots, we're just going
1111      * to use the first key slot */
1112     splitkeylen = luks->header.key_bytes * QCRYPTO_BLOCK_LUKS_STRIPES;
1113     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1114         luks->header.key_slots[i].active = i == 0 ?
1115             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED :
1116             QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
1117         luks->header.key_slots[i].stripes = QCRYPTO_BLOCK_LUKS_STRIPES;
1118
1119         /* This calculation doesn't match that shown in the spec,
1120          * but instead follows the cryptsetup implementation.
1121          */
1122         luks->header.key_slots[i].key_offset =
1123             (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1124              QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1125             (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1126                       (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1127                        QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) * i);
1128     }
1129
1130     if (qcrypto_random_bytes(luks->header.key_slots[0].salt,
1131                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1132                              errp) < 0) {
1133         goto error;
1134     }
1135
1136     /* Again we determine how many iterations are required to
1137      * hash the user password while consuming 1 second of compute
1138      * time */
1139     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1140                                        (uint8_t *)password, strlen(password),
1141                                        luks->header.key_slots[0].salt,
1142                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1143                                        luks->header.key_bytes,
1144                                        &local_err);
1145     if (local_err) {
1146         error_propagate(errp, local_err);
1147         goto error;
1148     }
1149
1150     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1151         error_setg_errno(errp, ERANGE,
1152                          "PBKDF iterations %llu too large to scale",
1153                          (unsigned long long)iters);
1154         goto error;
1155     }
1156
1157     /* iter_time was in millis, but count_iters reported for secs */
1158     iters = iters * luks_opts.iter_time / 1000;
1159
1160     if (iters > UINT32_MAX) {
1161         error_setg_errno(errp, ERANGE,
1162                          "PBKDF iterations %llu larger than %u",
1163                          (unsigned long long)iters, UINT32_MAX);
1164         goto error;
1165     }
1166
1167     luks->header.key_slots[0].iterations =
1168         MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);
1169
1170
1171     /* Generate a key that we'll use to encrypt the master
1172      * key, from the user's password
1173      */
1174     slotkey = g_new0(uint8_t, luks->header.key_bytes);
1175     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1176                        (uint8_t *)password, strlen(password),
1177                        luks->header.key_slots[0].salt,
1178                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1179                        luks->header.key_slots[0].iterations,
1180                        slotkey, luks->header.key_bytes,
1181                        errp) < 0) {
1182         goto error;
1183     }
1184
1185
1186     /* Setup the encryption objects needed to encrypt the
1187      * master key material
1188      */
1189     cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
1190                                 luks_opts.cipher_mode,
1191                                 slotkey, luks->header.key_bytes,
1192                                 errp);
1193     if (!cipher) {
1194         goto error;
1195     }
1196
1197     ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1198                               ivcipheralg,
1199                               luks_opts.ivgen_hash_alg,
1200                               slotkey, luks->header.key_bytes,
1201                               errp);
1202     if (!ivgen) {
1203         goto error;
1204     }
1205
1206     /* Before storing the master key, we need to vastly
1207      * increase its size, as protection against forensic
1208      * disk data recovery */
1209     splitkey = g_new0(uint8_t, splitkeylen);
1210
1211     if (qcrypto_afsplit_encode(luks_opts.hash_alg,
1212                                luks->header.key_bytes,
1213                                luks->header.key_slots[0].stripes,
1214                                masterkey,
1215                                splitkey,
1216                                errp) < 0) {
1217         goto error;
1218     }
1219
1220     /* Now we encrypt the split master key with the key generated
1221      * from the user's password, before storing it */
1222     if (qcrypto_block_encrypt_helper(cipher, block->niv, ivgen,
1223                                      QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1224                                      0,
1225                                      splitkey,
1226                                      splitkeylen,
1227                                      errp) < 0) {
1228         goto error;
1229     }
1230
1231
1232     /* The total size of the LUKS headers is the partition header + key
1233      * slot headers, rounded up to the nearest sector, combined with
1234      * the size of each master key material region, also rounded up
1235      * to the nearest sector */
1236     luks->header.payload_offset =
1237         (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1238          QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1239         (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1240                   (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1241                    QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) *
1242          QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
1243
1244     block->payload_offset = luks->header.payload_offset *
1245         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1246
1247     /* Reserve header space to match payload offset */
1248     initfunc(block, opaque, block->payload_offset, &local_err);
1249     if (local_err) {
1250         error_propagate(errp, local_err);
1251         goto error;
1252     }
1253
1254     /* Everything on disk uses Big Endian, so flip header fields
1255      * before writing them */
1256     cpu_to_be16s(&luks->header.version);
1257     cpu_to_be32s(&luks->header.payload_offset);
1258     cpu_to_be32s(&luks->header.key_bytes);
1259     cpu_to_be32s(&luks->header.master_key_iterations);
1260
1261     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1262         cpu_to_be32s(&luks->header.key_slots[i].active);
1263         cpu_to_be32s(&luks->header.key_slots[i].iterations);
1264         cpu_to_be32s(&luks->header.key_slots[i].key_offset);
1265         cpu_to_be32s(&luks->header.key_slots[i].stripes);
1266     }
1267
1268
1269     /* Write out the partition header and key slot headers */
1270     writefunc(block, opaque, 0,
1271               (const uint8_t *)&luks->header,
1272               sizeof(luks->header),
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, opaque,
1299                   luks->header.key_slots[0].key_offset *
1300                   QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1301                   splitkey, splitkeylen,
1302                   errp) != splitkeylen) {
1303         goto error;
1304     }
1305
1306     luks->cipher_alg = luks_opts.cipher_alg;
1307     luks->cipher_mode = luks_opts.cipher_mode;
1308     luks->ivgen_alg = luks_opts.ivgen_alg;
1309     luks->ivgen_hash_alg = luks_opts.ivgen_hash_alg;
1310     luks->hash_alg = luks_opts.hash_alg;
1311
1312     memset(masterkey, 0, luks->header.key_bytes);
1313     g_free(masterkey);
1314     memset(slotkey, 0, luks->header.key_bytes);
1315     g_free(slotkey);
1316     g_free(splitkey);
1317     g_free(password);
1318     g_free(cipher_mode_spec);
1319
1320     qcrypto_ivgen_free(ivgen);
1321     qcrypto_cipher_free(cipher);
1322
1323     return 0;
1324
1325  error:
1326     if (masterkey) {
1327         memset(masterkey, 0, luks->header.key_bytes);
1328     }
1329     g_free(masterkey);
1330     if (slotkey) {
1331         memset(slotkey, 0, luks->header.key_bytes);
1332     }
1333     g_free(slotkey);
1334     g_free(splitkey);
1335     g_free(password);
1336     g_free(cipher_mode_spec);
1337
1338     qcrypto_ivgen_free(ivgen);
1339     qcrypto_cipher_free(cipher);
1340
1341     g_free(luks);
1342     return -1;
1343 }
1344
1345
1346 static int qcrypto_block_luks_get_info(QCryptoBlock *block,
1347                                        QCryptoBlockInfo *info,
1348                                        Error **errp)
1349 {
1350     QCryptoBlockLUKS *luks = block->opaque;
1351     QCryptoBlockInfoLUKSSlot *slot;
1352     QCryptoBlockInfoLUKSSlotList *slots = NULL, **prev = &info->u.luks.slots;
1353     size_t i;
1354
1355     info->u.luks.cipher_alg = luks->cipher_alg;
1356     info->u.luks.cipher_mode = luks->cipher_mode;
1357     info->u.luks.ivgen_alg = luks->ivgen_alg;
1358     if (info->u.luks.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1359         info->u.luks.has_ivgen_hash_alg = true;
1360         info->u.luks.ivgen_hash_alg = luks->ivgen_hash_alg;
1361     }
1362     info->u.luks.hash_alg = luks->hash_alg;
1363     info->u.luks.payload_offset = block->payload_offset;
1364     info->u.luks.master_key_iters = luks->header.master_key_iterations;
1365     info->u.luks.uuid = g_strndup((const char *)luks->header.uuid,
1366                                   sizeof(luks->header.uuid));
1367
1368     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1369         slots = g_new0(QCryptoBlockInfoLUKSSlotList, 1);
1370         *prev = slots;
1371
1372         slots->value = slot = g_new0(QCryptoBlockInfoLUKSSlot, 1);
1373         slot->active = luks->header.key_slots[i].active ==
1374             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
1375         slot->key_offset = luks->header.key_slots[i].key_offset
1376              * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1377         if (slot->active) {
1378             slot->has_iters = true;
1379             slot->iters = luks->header.key_slots[i].iterations;
1380             slot->has_stripes = true;
1381             slot->stripes = luks->header.key_slots[i].stripes;
1382         }
1383
1384         prev = &slots->next;
1385     }
1386
1387     return 0;
1388 }
1389
1390
1391 static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
1392 {
1393     g_free(block->opaque);
1394 }
1395
1396
1397 static int
1398 qcrypto_block_luks_decrypt(QCryptoBlock *block,
1399                            uint64_t startsector,
1400                            uint8_t *buf,
1401                            size_t len,
1402                            Error **errp)
1403 {
1404     return qcrypto_block_decrypt_helper(block->cipher,
1405                                         block->niv, block->ivgen,
1406                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1407                                         startsector, buf, len, errp);
1408 }
1409
1410
1411 static int
1412 qcrypto_block_luks_encrypt(QCryptoBlock *block,
1413                            uint64_t startsector,
1414                            uint8_t *buf,
1415                            size_t len,
1416                            Error **errp)
1417 {
1418     return qcrypto_block_encrypt_helper(block->cipher,
1419                                         block->niv, block->ivgen,
1420                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1421                                         startsector, buf, len, errp);
1422 }
1423
1424
1425 const QCryptoBlockDriver qcrypto_block_driver_luks = {
1426     .open = qcrypto_block_luks_open,
1427     .create = qcrypto_block_luks_create,
1428     .get_info = qcrypto_block_luks_get_info,
1429     .cleanup = qcrypto_block_luks_cleanup,
1430     .decrypt = qcrypto_block_luks_decrypt,
1431     .encrypt = qcrypto_block_luks_encrypt,
1432     .has_format = qcrypto_block_luks_has_format,
1433 };