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_sector;
 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_sector;
 176
 177     /* Number of key bytes */
 178     uint32_t master_key_len;
 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_sector * 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.master_key_len);
 588     *masterkeylen = luks->header.master_key_len;
 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_sector);
 681     be32_to_cpus(&luks->header.master_key_len);
 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_sector);
 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 =
 747         qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
 748                                               ciphermode,
 749                                               luks->header.master_key_len,
 750                                               &local_err);
 751     if (local_err) {
 752         ret = -ENOTSUP;
 753         error_propagate(errp, local_err);
 754         goto fail;
 755     }
 756
 757     hash = qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
 758                                                &local_err);
 759     if (local_err) {
 760         ret = -ENOTSUP;
 761         error_propagate(errp, local_err);
 762         goto fail;
 763     }
 764
 765     ivalg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
 766                                                  &local_err);
 767     if (local_err) {
 768         ret = -ENOTSUP;
 769         error_propagate(errp, local_err);
 770         goto fail;
 771     }
 772
 773     if (ivalg == QCRYPTO_IVGEN_ALG_ESSIV) {
 774         if (!ivhash_name) {
 775             ret = -EINVAL;
 776             error_setg(errp, "Missing IV generator hash specification");
 777             goto fail;
 778         }
 779         ivcipheralg = qcrypto_block_luks_essiv_cipher(cipheralg,
 780                                                       ivhash,
 781                                                       &local_err);
 782         if (local_err) {
 783             ret = -ENOTSUP;
 784             error_propagate(errp, local_err);
 785             goto fail;
 786         }
 787     } else {
 788         /* Note we parsed the ivhash_name earlier in the cipher_mode
 789          * spec string even with plain/plain64 ivgens, but we
 790          * will ignore it, since it is irrelevant for these ivgens.
 791          * This is for compat with dm-crypt which will silently
 792          * ignore hash names with these ivgens rather than report
 793          * an error about the invalid usage
 794          */
 795         ivcipheralg = cipheralg;
 796     }
 797
 798     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
 799         /* Try to find which key slot our password is valid for
 800          * and unlock the master key from that slot.
 801          */
 802         if (qcrypto_block_luks_find_key(block,
 803                                         password,
 804                                         cipheralg, ciphermode,
 805                                         hash,
 806                                         ivalg,
 807                                         ivcipheralg,
 808                                         ivhash,
 809                                         &masterkey, &masterkeylen,
 810                                         readfunc, opaque,
 811                                         errp) < 0) {
 812             ret = -EACCES;
 813             goto fail;
 814         }
 815
 816         /* We have a valid master key now, so can setup the
 817          * block device payload decryption objects
 818          */
 819         block->kdfhash = hash;
 820         block->niv = qcrypto_cipher_get_iv_len(cipheralg,
 821                                                ciphermode);
 822         block->ivgen = qcrypto_ivgen_new(ivalg,
 823                                          ivcipheralg,
 824                                          ivhash,
 825                                          masterkey, masterkeylen,
 826                                          errp);
 827         if (!block->ivgen) {
 828             ret = -ENOTSUP;
 829             goto fail;
 830         }
 831
 832         ret = qcrypto_block_init_cipher(block, cipheralg, ciphermode,
 833                                         masterkey, masterkeylen, n_threads,
 834                                         errp);
 835         if (ret < 0) {
 836             ret = -ENOTSUP;
 837             goto fail;
 838         }
 839     }
 840
 841     block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
 842     block->payload_offset = luks->header.payload_offset_sector *
 843         block->sector_size;
 844
 845     luks->cipher_alg = cipheralg;
 846     luks->cipher_mode = ciphermode;
 847     luks->ivgen_alg = ivalg;
 848     luks->ivgen_hash_alg = ivhash;
 849     luks->hash_alg = hash;
 850
 851     return 0;
 852
 853  fail:
 854     qcrypto_block_free_cipher(block);
 855     qcrypto_ivgen_free(block->ivgen);
 856     g_free(luks);
 857     return ret;
 858 }
 859
 860
 861 static void
 862 qcrypto_block_luks_uuid_gen(uint8_t *uuidstr)
 863 {
 864     QemuUUID uuid;
 865     qemu_uuid_generate(&uuid);
 866     qemu_uuid_unparse(&uuid, (char *)uuidstr);
 867 }
 868
 869 static int
 870 qcrypto_block_luks_create(QCryptoBlock *block,
 871                           QCryptoBlockCreateOptions *options,
 872                           const char *optprefix,
 873                           QCryptoBlockInitFunc initfunc,
 874                           QCryptoBlockWriteFunc writefunc,
 875                           void *opaque,
 876                           Error **errp)
 877 {
 878     QCryptoBlockLUKS *luks;
 879     QCryptoBlockCreateOptionsLUKS luks_opts;
 880     Error *local_err = NULL;
 881     g_autofree uint8_t *masterkey = NULL;
 882     g_autofree uint8_t *slotkey = NULL;
 883     g_autofree uint8_t *splitkey = NULL;
 884     size_t splitkeylen = 0;
 885     size_t i;
 886     g_autoptr(QCryptoCipher) cipher = NULL;
 887     g_autoptr(QCryptoIVGen) ivgen = NULL;
 888     g_autofree char *password = NULL;
 889     const char *cipher_alg;
 890     const char *cipher_mode;
 891     const char *ivgen_alg;
 892     const char *ivgen_hash_alg = NULL;
 893     const char *hash_alg;
 894     g_autofree char *cipher_mode_spec = NULL;
 895     QCryptoCipherAlgorithm ivcipheralg = 0;
 896     uint64_t iters;
 897
 898     memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
 899     if (!luks_opts.has_iter_time) {
 900         luks_opts.iter_time = 2000;
 901     }
 902     if (!luks_opts.has_cipher_alg) {
 903         luks_opts.cipher_alg = QCRYPTO_CIPHER_ALG_AES_256;
 904     }
 905     if (!luks_opts.has_cipher_mode) {
 906         luks_opts.cipher_mode = QCRYPTO_CIPHER_MODE_XTS;
 907     }
 908     if (!luks_opts.has_ivgen_alg) {
 909         luks_opts.ivgen_alg = QCRYPTO_IVGEN_ALG_PLAIN64;
 910     }
 911     if (!luks_opts.has_hash_alg) {
 912         luks_opts.hash_alg = QCRYPTO_HASH_ALG_SHA256;
 913     }
 914     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
 915         if (!luks_opts.has_ivgen_hash_alg) {
 916             luks_opts.ivgen_hash_alg = QCRYPTO_HASH_ALG_SHA256;
 917             luks_opts.has_ivgen_hash_alg = true;
 918         }
 919     }
 920     /* Note we're allowing ivgen_hash_alg to be set even for
 921      * non-essiv iv generators that don't need a hash. It will
 922      * be silently ignored, for compatibility with dm-crypt */
 923
 924     if (!options->u.luks.key_secret) {
 925         error_setg(errp, "Parameter '%skey-secret' is required for cipher",
 926                    optprefix ? optprefix : "");
 927         return -1;
 928     }
 929     password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret, errp);
 930     if (!password) {
 931         return -1;
 932     }
 933
 934     luks = g_new0(QCryptoBlockLUKS, 1);
 935     block->opaque = luks;
 936
 937     memcpy(luks->header.magic, qcrypto_block_luks_magic,
 938            QCRYPTO_BLOCK_LUKS_MAGIC_LEN);
 939
 940     /* We populate the header in native endianness initially and
 941      * then convert everything to big endian just before writing
 942      * it out to disk
 943      */
 944     luks->header.version = QCRYPTO_BLOCK_LUKS_VERSION;
 945     qcrypto_block_luks_uuid_gen(luks->header.uuid);
 946
 947     cipher_alg = qcrypto_block_luks_cipher_alg_lookup(luks_opts.cipher_alg,
 948                                                       errp);
 949     if (!cipher_alg) {
 950         goto error;
 951     }
 952
 953     cipher_mode = QCryptoCipherMode_str(luks_opts.cipher_mode);
 954     ivgen_alg = QCryptoIVGenAlgorithm_str(luks_opts.ivgen_alg);
 955     if (luks_opts.has_ivgen_hash_alg) {
 956         ivgen_hash_alg = QCryptoHashAlgorithm_str(luks_opts.ivgen_hash_alg);
 957         cipher_mode_spec = g_strdup_printf("%s-%s:%s", cipher_mode, ivgen_alg,
 958                                            ivgen_hash_alg);
 959     } else {
 960         cipher_mode_spec = g_strdup_printf("%s-%s", cipher_mode, ivgen_alg);
 961     }
 962     hash_alg = QCryptoHashAlgorithm_str(luks_opts.hash_alg);
 963
 964
 965     if (strlen(cipher_alg) >= QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN) {
 966         error_setg(errp, "Cipher name '%s' is too long for LUKS header",
 967                    cipher_alg);
 968         goto error;
 969     }
 970     if (strlen(cipher_mode_spec) >= QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN) {
 971         error_setg(errp, "Cipher mode '%s' is too long for LUKS header",
 972                    cipher_mode_spec);
 973         goto error;
 974     }
 975     if (strlen(hash_alg) >= QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN) {
 976         error_setg(errp, "Hash name '%s' is too long for LUKS header",
 977                    hash_alg);
 978         goto error;
 979     }
 980
 981     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
 982         ivcipheralg = qcrypto_block_luks_essiv_cipher(luks_opts.cipher_alg,
 983                                                       luks_opts.ivgen_hash_alg,
 984                                                       &local_err);
 985         if (local_err) {
 986             error_propagate(errp, local_err);
 987             goto error;
 988         }
 989     } else {
 990         ivcipheralg = luks_opts.cipher_alg;
 991     }
 992
 993     strcpy(luks->header.cipher_name, cipher_alg);
 994     strcpy(luks->header.cipher_mode, cipher_mode_spec);
 995     strcpy(luks->header.hash_spec, hash_alg);
 996
 997     luks->header.master_key_len =
 998         qcrypto_cipher_get_key_len(luks_opts.cipher_alg);
 999
1000     if (luks_opts.cipher_mode == QCRYPTO_CIPHER_MODE_XTS) {
1001         luks->header.master_key_len *= 2;
1002     }
1003
1004     /* Generate the salt used for hashing the master key
1005      * with PBKDF later
1006      */
1007     if (qcrypto_random_bytes(luks->header.master_key_salt,
1008                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1009                              errp) < 0) {
1010         goto error;
1011     }
1012
1013     /* Generate random master key */
1014     masterkey = g_new0(uint8_t, luks->header.master_key_len);
1015     if (qcrypto_random_bytes(masterkey,
1016                              luks->header.master_key_len, errp) < 0) {
1017         goto error;
1018     }
1019
1020
1021     /* Setup the block device payload encryption objects */
1022     if (qcrypto_block_init_cipher(block, luks_opts.cipher_alg,
1023                                   luks_opts.cipher_mode, masterkey,
1024                                   luks->header.master_key_len, 1, errp) < 0) {
1025         goto error;
1026     }
1027
1028     block->kdfhash = luks_opts.hash_alg;
1029     block->niv = qcrypto_cipher_get_iv_len(luks_opts.cipher_alg,
1030                                            luks_opts.cipher_mode);
1031     block->ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1032                                      ivcipheralg,
1033                                      luks_opts.ivgen_hash_alg,
1034                                      masterkey, luks->header.master_key_len,
1035                                      errp);
1036
1037     if (!block->ivgen) {
1038         goto error;
1039     }
1040
1041
1042     /* Determine how many iterations we need to hash the master
1043      * key, in order to have 1 second of compute time used
1044      */
1045     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1046                                        masterkey, luks->header.master_key_len,
1047                                        luks->header.master_key_salt,
1048                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1049                                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1050                                        &local_err);
1051     if (local_err) {
1052         error_propagate(errp, local_err);
1053         goto error;
1054     }
1055
1056     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1057         error_setg_errno(errp, ERANGE,
1058                          "PBKDF iterations %llu too large to scale",
1059                          (unsigned long long)iters);
1060         goto error;
1061     }
1062
1063     /* iter_time was in millis, but count_iters reported for secs */
1064     iters = iters * luks_opts.iter_time / 1000;
1065
1066     /* Why /= 8 ?  That matches cryptsetup, but there's no
1067      * explanation why they chose /= 8... Probably so that
1068      * if all 8 keyslots are active we only spend 1 second
1069      * in total time to check all keys */
1070     iters /= 8;
1071     if (iters > UINT32_MAX) {
1072         error_setg_errno(errp, ERANGE,
1073                          "PBKDF iterations %llu larger than %u",
1074                          (unsigned long long)iters, UINT32_MAX);
1075         goto error;
1076     }
1077     iters = MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS);
1078     luks->header.master_key_iterations = iters;
1079
1080     /* Hash the master key, saving the result in the LUKS
1081      * header. This hash is used when opening the encrypted
1082      * device to verify that the user password unlocked a
1083      * valid master key
1084      */
1085     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1086                        masterkey, luks->header.master_key_len,
1087                        luks->header.master_key_salt,
1088                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1089                        luks->header.master_key_iterations,
1090                        luks->header.master_key_digest,
1091                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1092                        errp) < 0) {
1093         goto error;
1094     }
1095
1096
1097     /* Although LUKS has multiple key slots, we're just going
1098      * to use the first key slot */
1099     splitkeylen = luks->header.master_key_len * QCRYPTO_BLOCK_LUKS_STRIPES;
1100     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1101         luks->header.key_slots[i].active = i == 0 ?
1102             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED :
1103             QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
1104         luks->header.key_slots[i].stripes = QCRYPTO_BLOCK_LUKS_STRIPES;
1105
1106         /* This calculation doesn't match that shown in the spec,
1107          * but instead follows the cryptsetup implementation.
1108          */
1109         luks->header.key_slots[i].key_offset_sector =
1110             (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1111              QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1112             (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1113                       (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1114                        QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) * i);
1115     }
1116
1117     if (qcrypto_random_bytes(luks->header.key_slots[0].salt,
1118                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1119                              errp) < 0) {
1120         goto error;
1121     }
1122
1123     /* Again we determine how many iterations are required to
1124      * hash the user password while consuming 1 second of compute
1125      * time */
1126     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1127                                        (uint8_t *)password, strlen(password),
1128                                        luks->header.key_slots[0].salt,
1129                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1130                                        luks->header.master_key_len,
1131                                        &local_err);
1132     if (local_err) {
1133         error_propagate(errp, local_err);
1134         goto error;
1135     }
1136
1137     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1138         error_setg_errno(errp, ERANGE,
1139                          "PBKDF iterations %llu too large to scale",
1140                          (unsigned long long)iters);
1141         goto error;
1142     }
1143
1144     /* iter_time was in millis, but count_iters reported for secs */
1145     iters = iters * luks_opts.iter_time / 1000;
1146
1147     if (iters > UINT32_MAX) {
1148         error_setg_errno(errp, ERANGE,
1149                          "PBKDF iterations %llu larger than %u",
1150                          (unsigned long long)iters, UINT32_MAX);
1151         goto error;
1152     }
1153
1154     luks->header.key_slots[0].iterations =
1155         MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);
1156
1157
1158     /* Generate a key that we'll use to encrypt the master
1159      * key, from the user's password
1160      */
1161     slotkey = g_new0(uint8_t, luks->header.master_key_len);
1162     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1163                        (uint8_t *)password, strlen(password),
1164                        luks->header.key_slots[0].salt,
1165                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1166                        luks->header.key_slots[0].iterations,
1167                        slotkey, luks->header.master_key_len,
1168                        errp) < 0) {
1169         goto error;
1170     }
1171
1172
1173     /* Setup the encryption objects needed to encrypt the
1174      * master key material
1175      */
1176     cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
1177                                 luks_opts.cipher_mode,
1178                                 slotkey, luks->header.master_key_len,
1179                                 errp);
1180     if (!cipher) {
1181         goto error;
1182     }
1183
1184     ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1185                               ivcipheralg,
1186                               luks_opts.ivgen_hash_alg,
1187                               slotkey, luks->header.master_key_len,
1188                               errp);
1189     if (!ivgen) {
1190         goto error;
1191     }
1192
1193     /* Before storing the master key, we need to vastly
1194      * increase its size, as protection against forensic
1195      * disk data recovery */
1196     splitkey = g_new0(uint8_t, splitkeylen);
1197
1198     if (qcrypto_afsplit_encode(luks_opts.hash_alg,
1199                                luks->header.master_key_len,
1200                                luks->header.key_slots[0].stripes,
1201                                masterkey,
1202                                splitkey,
1203                                errp) < 0) {
1204         goto error;
1205     }
1206
1207     /* Now we encrypt the split master key with the key generated
1208      * from the user's password, before storing it */
1209     if (qcrypto_block_cipher_encrypt_helper(cipher, block->niv, ivgen,
1210                                             QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1211                                             0,
1212                                             splitkey,
1213                                             splitkeylen,
1214                                             errp) < 0) {
1215         goto error;
1216     }
1217
1218
1219     /* The total size of the LUKS headers is the partition header + key
1220      * slot headers, rounded up to the nearest sector, combined with
1221      * the size of each master key material region, also rounded up
1222      * to the nearest sector */
1223     luks->header.payload_offset_sector =
1224         (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1225          QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1226         (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1227                   (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1228                    QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) *
1229          QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
1230
1231     block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1232     block->payload_offset = luks->header.payload_offset_sector *
1233         block->sector_size;
1234
1235     /* Reserve header space to match payload offset */
1236     initfunc(block, block->payload_offset, opaque, &local_err);
1237     if (local_err) {
1238         error_propagate(errp, local_err);
1239         goto error;
1240     }
1241
1242     /* Everything on disk uses Big Endian, so flip header fields
1243      * before writing them */
1244     cpu_to_be16s(&luks->header.version);
1245     cpu_to_be32s(&luks->header.payload_offset_sector);
1246     cpu_to_be32s(&luks->header.master_key_len);
1247     cpu_to_be32s(&luks->header.master_key_iterations);
1248
1249     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1250         cpu_to_be32s(&luks->header.key_slots[i].active);
1251         cpu_to_be32s(&luks->header.key_slots[i].iterations);
1252         cpu_to_be32s(&luks->header.key_slots[i].key_offset_sector);
1253         cpu_to_be32s(&luks->header.key_slots[i].stripes);
1254     }
1255
1256
1257     /* Write out the partition header and key slot headers */
1258     writefunc(block, 0,
1259               (const uint8_t *)&luks->header,
1260               sizeof(luks->header),
1261               opaque,
1262               &local_err);
1263
1264     /* Delay checking local_err until we've byte-swapped */
1265
1266     /* Byte swap the header back to native, in case we need
1267      * to read it again later */
1268     be16_to_cpus(&luks->header.version);
1269     be32_to_cpus(&luks->header.payload_offset_sector);
1270     be32_to_cpus(&luks->header.master_key_len);
1271     be32_to_cpus(&luks->header.master_key_iterations);
1272
1273     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1274         be32_to_cpus(&luks->header.key_slots[i].active);
1275         be32_to_cpus(&luks->header.key_slots[i].iterations);
1276         be32_to_cpus(&luks->header.key_slots[i].key_offset_sector);
1277         be32_to_cpus(&luks->header.key_slots[i].stripes);
1278     }
1279
1280     if (local_err) {
1281         error_propagate(errp, local_err);
1282         goto error;
1283     }
1284
1285     /* Write out the master key material, starting at the
1286      * sector immediately following the partition header. */
1287     if (writefunc(block,
1288                   luks->header.key_slots[0].key_offset_sector *
1289                   QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1290                   splitkey, splitkeylen,
1291                   opaque,
1292                   errp) != splitkeylen) {
1293         goto error;
1294     }
1295
1296     luks->cipher_alg = luks_opts.cipher_alg;
1297     luks->cipher_mode = luks_opts.cipher_mode;
1298     luks->ivgen_alg = luks_opts.ivgen_alg;
1299     luks->ivgen_hash_alg = luks_opts.ivgen_hash_alg;
1300     luks->hash_alg = luks_opts.hash_alg;
1301
1302     memset(masterkey, 0, luks->header.master_key_len);
1303     memset(slotkey, 0, luks->header.master_key_len);
1304
1305     return 0;
1306
1307  error:
1308     if (masterkey) {
1309         memset(masterkey, 0, luks->header.master_key_len);
1310     }
1311     if (slotkey) {
1312         memset(slotkey, 0, luks->header.master_key_len);
1313     }
1314
1315     qcrypto_block_free_cipher(block);
1316     qcrypto_ivgen_free(block->ivgen);
1317
1318     g_free(luks);
1319     return -1;
1320 }
1321
1322
1323 static int qcrypto_block_luks_get_info(QCryptoBlock *block,
1324                                        QCryptoBlockInfo *info,
1325                                        Error **errp)
1326 {
1327     QCryptoBlockLUKS *luks = block->opaque;
1328     QCryptoBlockInfoLUKSSlot *slot;
1329     QCryptoBlockInfoLUKSSlotList *slots = NULL, **prev = &info->u.luks.slots;
1330     size_t i;
1331
1332     info->u.luks.cipher_alg = luks->cipher_alg;
1333     info->u.luks.cipher_mode = luks->cipher_mode;
1334     info->u.luks.ivgen_alg = luks->ivgen_alg;
1335     if (info->u.luks.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1336         info->u.luks.has_ivgen_hash_alg = true;
1337         info->u.luks.ivgen_hash_alg = luks->ivgen_hash_alg;
1338     }
1339     info->u.luks.hash_alg = luks->hash_alg;
1340     info->u.luks.payload_offset = block->payload_offset;
1341     info->u.luks.master_key_iters = luks->header.master_key_iterations;
1342     info->u.luks.uuid = g_strndup((const char *)luks->header.uuid,
1343                                   sizeof(luks->header.uuid));
1344
1345     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1346         slots = g_new0(QCryptoBlockInfoLUKSSlotList, 1);
1347         *prev = slots;
1348
1349         slots->value = slot = g_new0(QCryptoBlockInfoLUKSSlot, 1);
1350         slot->active = luks->header.key_slots[i].active ==
1351             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
1352         slot->key_offset = luks->header.key_slots[i].key_offset_sector
1353              * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1354         if (slot->active) {
1355             slot->has_iters = true;
1356             slot->iters = luks->header.key_slots[i].iterations;
1357             slot->has_stripes = true;
1358             slot->stripes = luks->header.key_slots[i].stripes;
1359         }
1360
1361         prev = &slots->next;
1362     }
1363
1364     return 0;
1365 }
1366
1367
1368 static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
1369 {
1370     g_free(block->opaque);
1371 }
1372
1373
1374 static int
1375 qcrypto_block_luks_decrypt(QCryptoBlock *block,
1376                            uint64_t offset,
1377                            uint8_t *buf,
1378                            size_t len,
1379                            Error **errp)
1380 {
1381     assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1382     assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1383     return qcrypto_block_decrypt_helper(block,
1384                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1385                                         offset, buf, len, errp);
1386 }
1387
1388
1389 static int
1390 qcrypto_block_luks_encrypt(QCryptoBlock *block,
1391                            uint64_t offset,
1392                            uint8_t *buf,
1393                            size_t len,
1394                            Error **errp)
1395 {
1396     assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1397     assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1398     return qcrypto_block_encrypt_helper(block,
1399                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1400                                         offset, buf, len, errp);
1401 }
1402
1403
1404 const QCryptoBlockDriver qcrypto_block_driver_luks = {
1405     .open = qcrypto_block_luks_open,
1406     .create = qcrypto_block_luks_create,
1407     .get_info = qcrypto_block_luks_get_info,
1408     .cleanup = qcrypto_block_luks_cleanup,
1409     .decrypt = qcrypto_block_luks_decrypt,
1410     .encrypt = qcrypto_block_luks_encrypt,
1411     .has_format = qcrypto_block_luks_has_format,
1412 };