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