crypto/block-luks.c

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