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
  33 #ifdef CONFIG_UUID
  34 #include <uuid/uuid.h>
  35 #endif
  36
  37 #include "qemu/coroutine.h"
  38
  39 /*
  40  * Reference for the LUKS format implemented here is
  41  *
  42  *   docs/on-disk-format.pdf
  43  *
  44  * in 'cryptsetup' package source code
  45  *
  46  * This file implements the 1.2.1 specification, dated
  47  * Oct 16, 2011.
  48  */
  49
  50 typedef struct QCryptoBlockLUKS QCryptoBlockLUKS;
  51 typedef struct QCryptoBlockLUKSHeader QCryptoBlockLUKSHeader;
  52 typedef struct QCryptoBlockLUKSKeySlot QCryptoBlockLUKSKeySlot;
  53
  54
  55 /* The following constants are all defined by the LUKS spec */
  56 #define QCRYPTO_BLOCK_LUKS_VERSION 1
  57
  58 #define QCRYPTO_BLOCK_LUKS_MAGIC_LEN 6
  59 #define QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN 32
  60 #define QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN 32
  61 #define QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN 32
  62 #define QCRYPTO_BLOCK_LUKS_DIGEST_LEN 20
  63 #define QCRYPTO_BLOCK_LUKS_SALT_LEN 32
  64 #define QCRYPTO_BLOCK_LUKS_UUID_LEN 40
  65 #define QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS 8
  66 #define QCRYPTO_BLOCK_LUKS_STRIPES 4000
  67 #define QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS 1000
  68 #define QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS 1000
  69 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET 4096
  70
  71 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED 0x0000DEAD
  72 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED 0x00AC71F3
  73
  74 #define QCRYPTO_BLOCK_LUKS_SECTOR_SIZE 512LL
  75
  76 static const char qcrypto_block_luks_magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN] = {
  77     'L', 'U', 'K', 'S', 0xBA, 0xBE
  78 };
  79
  80 typedef struct QCryptoBlockLUKSNameMap QCryptoBlockLUKSNameMap;
  81 struct QCryptoBlockLUKSNameMap {
  82     const char *name;
  83     int id;
  84 };
  85
  86 typedef struct QCryptoBlockLUKSCipherSizeMap QCryptoBlockLUKSCipherSizeMap;
  87 struct QCryptoBlockLUKSCipherSizeMap {
  88     uint32_t key_bytes;
  89     int id;
  90 };
  91 typedef struct QCryptoBlockLUKSCipherNameMap QCryptoBlockLUKSCipherNameMap;
  92 struct QCryptoBlockLUKSCipherNameMap {
  93     const char *name;
  94     const QCryptoBlockLUKSCipherSizeMap *sizes;
  95 };
  96
  97
  98 static const QCryptoBlockLUKSCipherSizeMap
  99 qcrypto_block_luks_cipher_size_map_aes[] = {
 100     { 16, QCRYPTO_CIPHER_ALG_AES_128 },
 101     { 24, QCRYPTO_CIPHER_ALG_AES_192 },
 102     { 32, QCRYPTO_CIPHER_ALG_AES_256 },
 103     { 0, 0 },
 104 };
 105
 106 static const QCryptoBlockLUKSCipherSizeMap
 107 qcrypto_block_luks_cipher_size_map_cast5[] = {
 108     { 16, QCRYPTO_CIPHER_ALG_CAST5_128 },
 109     { 0, 0 },
 110 };
 111
 112 static const QCryptoBlockLUKSCipherSizeMap
 113 qcrypto_block_luks_cipher_size_map_serpent[] = {
 114     { 16, QCRYPTO_CIPHER_ALG_SERPENT_128 },
 115     { 24, QCRYPTO_CIPHER_ALG_SERPENT_192 },
 116     { 32, QCRYPTO_CIPHER_ALG_SERPENT_256 },
 117     { 0, 0 },
 118 };
 119
 120 static const QCryptoBlockLUKSCipherSizeMap
 121 qcrypto_block_luks_cipher_size_map_twofish[] = {
 122     { 16, QCRYPTO_CIPHER_ALG_TWOFISH_128 },
 123     { 24, QCRYPTO_CIPHER_ALG_TWOFISH_192 },
 124     { 32, QCRYPTO_CIPHER_ALG_TWOFISH_256 },
 125     { 0, 0 },
 126 };
 127
 128 static const QCryptoBlockLUKSCipherNameMap
 129 qcrypto_block_luks_cipher_name_map[] = {
 130     { "aes", qcrypto_block_luks_cipher_size_map_aes },
 131     { "cast5", qcrypto_block_luks_cipher_size_map_cast5 },
 132     { "serpent", qcrypto_block_luks_cipher_size_map_serpent },
 133     { "twofish", qcrypto_block_luks_cipher_size_map_twofish },
 134 };
 135
 136
 137 /*
 138  * This struct is written to disk in big-endian format,
 139  * but operated upon in native-endian format.
 140  */
 141 struct QCryptoBlockLUKSKeySlot {
 142     /* state of keyslot, enabled/disable */
 143     uint32_t active;
 144     /* iterations for PBKDF2 */
 145     uint32_t iterations;
 146     /* salt for PBKDF2 */
 147     uint8_t salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
 148     /* start sector of key material */
 149     uint32_t key_offset;
 150     /* number of anti-forensic stripes */
 151     uint32_t stripes;
 152 } QEMU_PACKED;
 153
 154 QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSKeySlot) != 48);
 155
 156
 157 /*
 158  * This struct is written to disk in big-endian format,
 159  * but operated upon in native-endian format.
 160  */
 161 struct QCryptoBlockLUKSHeader {
 162     /* 'L', 'U', 'K', 'S', '0xBA', '0xBE' */
 163     char magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN];
 164
 165     /* LUKS version, currently 1 */
 166     uint16_t version;
 167
 168     /* cipher name specification (aes, etc) */
 169     char cipher_name[QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN];
 170
 171     /* cipher mode specification (cbc-plain, xts-essiv:sha256, etc) */
 172     char cipher_mode[QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN];
 173
 174     /* hash specification (sha256, etc) */
 175     char hash_spec[QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN];
 176
 177     /* start offset of the volume data (in 512 byte sectors) */
 178     uint32_t payload_offset;
 179
 180     /* Number of key bytes */
 181     uint32_t key_bytes;
 182
 183     /* master key checksum after PBKDF2 */
 184     uint8_t master_key_digest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
 185
 186     /* salt for master key PBKDF2 */
 187     uint8_t master_key_salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
 188
 189     /* iterations for master key PBKDF2 */
 190     uint32_t master_key_iterations;
 191
 192     /* UUID of the partition in standard ASCII representation */
 193     uint8_t uuid[QCRYPTO_BLOCK_LUKS_UUID_LEN];
 194
 195     /* key slots */
 196     QCryptoBlockLUKSKeySlot key_slots[QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS];
 197 } QEMU_PACKED;
 198
 199 QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSHeader) != 592);
 200
 201
 202 struct QCryptoBlockLUKS {
 203     QCryptoBlockLUKSHeader header;
 204
 205     /* Cache parsed versions of what's in header fields,
 206      * as we can't rely on QCryptoBlock.cipher being
 207      * non-NULL */
 208     QCryptoCipherAlgorithm cipher_alg;
 209     QCryptoCipherMode cipher_mode;
 210     QCryptoIVGenAlgorithm ivgen_alg;
 211     QCryptoHashAlgorithm ivgen_hash_alg;
 212     QCryptoHashAlgorithm hash_alg;
 213 };
 214
 215
 216 static int qcrypto_block_luks_cipher_name_lookup(const char *name,
 217                                                  QCryptoCipherMode mode,
 218                                                  uint32_t key_bytes,
 219                                                  Error **errp)
 220 {
 221     const QCryptoBlockLUKSCipherNameMap *map =
 222         qcrypto_block_luks_cipher_name_map;
 223     size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
 224     size_t i, j;
 225
 226     if (mode == QCRYPTO_CIPHER_MODE_XTS) {
 227         key_bytes /= 2;
 228     }
 229
 230     for (i = 0; i < maplen; i++) {
 231         if (!g_str_equal(map[i].name, name)) {
 232             continue;
 233         }
 234         for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
 235             if (map[i].sizes[j].key_bytes == key_bytes) {
 236                 return map[i].sizes[j].id;
 237             }
 238         }
 239     }
 240
 241     error_setg(errp, "Algorithm %s with key size %d bytes not supported",
 242                name, key_bytes);
 243     return 0;
 244 }
 245
 246 static const char *
 247 qcrypto_block_luks_cipher_alg_lookup(QCryptoCipherAlgorithm alg,
 248                                      Error **errp)
 249 {
 250     const QCryptoBlockLUKSCipherNameMap *map =
 251         qcrypto_block_luks_cipher_name_map;
 252     size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
 253     size_t i, j;
 254     for (i = 0; i < maplen; i++) {
 255         for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
 256             if (map[i].sizes[j].id == alg) {
 257                 return map[i].name;
 258             }
 259         }
 260     }
 261
 262     error_setg(errp, "Algorithm '%s' not supported",
 263                QCryptoCipherAlgorithm_lookup[alg]);
 264     return NULL;
 265 }
 266
 267 /* XXX replace with qapi_enum_parse() in future, when we can
 268  * make that function emit a more friendly error message */
 269 static int qcrypto_block_luks_name_lookup(const char *name,
 270                                           const char *const *map,
 271                                           size_t maplen,
 272                                           const char *type,
 273                                           Error **errp)
 274 {
 275     size_t i;
 276     for (i = 0; i < maplen; i++) {
 277         if (g_str_equal(map[i], name)) {
 278             return i;
 279         }
 280     }
 281
 282     error_setg(errp, "%s %s not supported", type, name);
 283     return 0;
 284 }
 285
 286 #define qcrypto_block_luks_cipher_mode_lookup(name, errp)               \
 287     qcrypto_block_luks_name_lookup(name,                                \
 288                                    QCryptoCipherMode_lookup,            \
 289                                    QCRYPTO_CIPHER_MODE__MAX,            \
 290                                    "Cipher mode",                       \
 291                                    errp)
 292
 293 #define qcrypto_block_luks_hash_name_lookup(name, errp)                 \
 294     qcrypto_block_luks_name_lookup(name,                                \
 295                                    QCryptoHashAlgorithm_lookup,         \
 296                                    QCRYPTO_HASH_ALG__MAX,               \
 297                                    "Hash algorithm",                    \
 298                                    errp)
 299
 300 #define qcrypto_block_luks_ivgen_name_lookup(name, errp)                \
 301     qcrypto_block_luks_name_lookup(name,                                \
 302                                    QCryptoIVGenAlgorithm_lookup,        \
 303                                    QCRYPTO_IVGEN_ALG__MAX,              \
 304                                    "IV generator",                      \
 305                                    errp)
 306
 307
 308 static bool
 309 qcrypto_block_luks_has_format(const uint8_t *buf,
 310                               size_t buf_size)
 311 {
 312     const QCryptoBlockLUKSHeader *luks_header = (const void *)buf;
 313
 314     if (buf_size >= offsetof(QCryptoBlockLUKSHeader, cipher_name) &&
 315         memcmp(luks_header->magic, qcrypto_block_luks_magic,
 316                QCRYPTO_BLOCK_LUKS_MAGIC_LEN) == 0 &&
 317         be16_to_cpu(luks_header->version) == QCRYPTO_BLOCK_LUKS_VERSION) {
 318         return true;
 319     } else {
 320         return false;
 321     }
 322 }
 323
 324
 325 /**
 326  * Deal with a quirk of dm-crypt usage of ESSIV.
 327  *
 328  * When calculating ESSIV IVs, the cipher length used by ESSIV
 329  * may be different from the cipher length used for the block
 330  * encryption, becauses dm-crypt uses the hash digest length
 331  * as the key size. ie, if you have AES 128 as the block cipher
 332  * and SHA 256 as ESSIV hash, then ESSIV will use AES 256 as
 333  * the cipher since that gets a key length matching the digest
 334  * size, not AES 128 with truncated digest as might be imagined
 335  */
 336 static QCryptoCipherAlgorithm
 337 qcrypto_block_luks_essiv_cipher(QCryptoCipherAlgorithm cipher,
 338                                 QCryptoHashAlgorithm hash,
 339                                 Error **errp)
 340 {
 341     size_t digestlen = qcrypto_hash_digest_len(hash);
 342     size_t keylen = qcrypto_cipher_get_key_len(cipher);
 343     if (digestlen == keylen) {
 344         return cipher;
 345     }
 346
 347     switch (cipher) {
 348     case QCRYPTO_CIPHER_ALG_AES_128:
 349     case QCRYPTO_CIPHER_ALG_AES_192:
 350     case QCRYPTO_CIPHER_ALG_AES_256:
 351         if (digestlen == qcrypto_cipher_get_key_len(
 352                 QCRYPTO_CIPHER_ALG_AES_128)) {
 353             return QCRYPTO_CIPHER_ALG_AES_128;
 354         } else if (digestlen == qcrypto_cipher_get_key_len(
 355                        QCRYPTO_CIPHER_ALG_AES_192)) {
 356             return QCRYPTO_CIPHER_ALG_AES_192;
 357         } else if (digestlen == qcrypto_cipher_get_key_len(
 358                        QCRYPTO_CIPHER_ALG_AES_256)) {
 359             return QCRYPTO_CIPHER_ALG_AES_256;
 360         } else {
 361             error_setg(errp, "No AES cipher with key size %zu available",
 362                        digestlen);
 363             return 0;
 364         }
 365         break;
 366     case QCRYPTO_CIPHER_ALG_SERPENT_128:
 367     case QCRYPTO_CIPHER_ALG_SERPENT_192:
 368     case QCRYPTO_CIPHER_ALG_SERPENT_256:
 369         if (digestlen == qcrypto_cipher_get_key_len(
 370                 QCRYPTO_CIPHER_ALG_SERPENT_128)) {
 371             return QCRYPTO_CIPHER_ALG_SERPENT_128;
 372         } else if (digestlen == qcrypto_cipher_get_key_len(
 373                        QCRYPTO_CIPHER_ALG_SERPENT_192)) {
 374             return QCRYPTO_CIPHER_ALG_SERPENT_192;
 375         } else if (digestlen == qcrypto_cipher_get_key_len(
 376                        QCRYPTO_CIPHER_ALG_SERPENT_256)) {
 377             return QCRYPTO_CIPHER_ALG_SERPENT_256;
 378         } else {
 379             error_setg(errp, "No Serpent cipher with key size %zu available",
 380                        digestlen);
 381             return 0;
 382         }
 383         break;
 384     case QCRYPTO_CIPHER_ALG_TWOFISH_128:
 385     case QCRYPTO_CIPHER_ALG_TWOFISH_192:
 386     case QCRYPTO_CIPHER_ALG_TWOFISH_256:
 387         if (digestlen == qcrypto_cipher_get_key_len(
 388                 QCRYPTO_CIPHER_ALG_TWOFISH_128)) {
 389             return QCRYPTO_CIPHER_ALG_TWOFISH_128;
 390         } else if (digestlen == qcrypto_cipher_get_key_len(
 391                        QCRYPTO_CIPHER_ALG_TWOFISH_192)) {
 392             return QCRYPTO_CIPHER_ALG_TWOFISH_192;
 393         } else if (digestlen == qcrypto_cipher_get_key_len(
 394                        QCRYPTO_CIPHER_ALG_TWOFISH_256)) {
 395             return QCRYPTO_CIPHER_ALG_TWOFISH_256;
 396         } else {
 397             error_setg(errp, "No Twofish cipher with key size %zu available",
 398                        digestlen);
 399             return 0;
 400         }
 401         break;
 402     default:
 403         error_setg(errp, "Cipher %s not supported with essiv",
 404                    QCryptoCipherAlgorithm_lookup[cipher]);
 405         return 0;
 406     }
 407 }
 408
 409 /*
 410  * Given a key slot, and user password, this will attempt to unlock
 411  * the master encryption key from the key slot.
 412  *
 413  * Returns:
 414  *    0 if the key slot is disabled, or key could not be decrypted
 415  *      with the provided password
 416  *    1 if the key slot is enabled, and key decrypted successfully
 417  *      with the provided password
 418  *   -1 if a fatal error occurred loading the key
 419  */
 420 static int
 421 qcrypto_block_luks_load_key(QCryptoBlock *block,
 422                             QCryptoBlockLUKSKeySlot *slot,
 423                             const char *password,
 424                             QCryptoCipherAlgorithm cipheralg,
 425                             QCryptoCipherMode ciphermode,
 426                             QCryptoHashAlgorithm hash,
 427                             QCryptoIVGenAlgorithm ivalg,
 428                             QCryptoCipherAlgorithm ivcipheralg,
 429                             QCryptoHashAlgorithm ivhash,
 430                             uint8_t *masterkey,
 431                             size_t masterkeylen,
 432                             QCryptoBlockReadFunc readfunc,
 433                             void *opaque,
 434                             Error **errp)
 435 {
 436     QCryptoBlockLUKS *luks = block->opaque;
 437     uint8_t *splitkey;
 438     size_t splitkeylen;
 439     uint8_t *possiblekey;
 440     int ret = -1;
 441     ssize_t rv;
 442     QCryptoCipher *cipher = NULL;
 443     uint8_t keydigest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
 444     QCryptoIVGen *ivgen = NULL;
 445     size_t niv;
 446
 447     if (slot->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
 448         return 0;
 449     }
 450
 451     splitkeylen = masterkeylen * slot->stripes;
 452     splitkey = g_new0(uint8_t, splitkeylen);
 453     possiblekey = g_new0(uint8_t, masterkeylen);
 454
 455     /*
 456      * The user password is used to generate a (possible)
 457      * decryption key. This may or may not successfully
 458      * decrypt the master key - we just blindly assume
 459      * the key is correct and validate the results of
 460      * decryption later.
 461      */
 462     if (qcrypto_pbkdf2(hash,
 463                        (const uint8_t *)password, strlen(password),
 464                        slot->salt, QCRYPTO_BLOCK_LUKS_SALT_LEN,
 465                        slot->iterations,
 466                        possiblekey, masterkeylen,
 467                        errp) < 0) {
 468         goto cleanup;
 469     }
 470
 471     /*
 472      * We need to read the master key material from the
 473      * LUKS key material header. What we're reading is
 474      * not the raw master key, but rather the data after
 475      * it has been passed through AFSplit and the result
 476      * then encrypted.
 477      */
 478     rv = readfunc(block,
 479                   slot->key_offset * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 480                   splitkey, splitkeylen,
 481                   errp,
 482                   opaque);
 483     if (rv < 0) {
 484         goto cleanup;
 485     }
 486
 487
 488     /* Setup the cipher/ivgen that we'll use to try to decrypt
 489      * the split master key material */
 490     cipher = qcrypto_cipher_new(cipheralg, ciphermode,
 491                                 possiblekey, masterkeylen,
 492                                 errp);
 493     if (!cipher) {
 494         goto cleanup;
 495     }
 496
 497     niv = qcrypto_cipher_get_iv_len(cipheralg,
 498                                     ciphermode);
 499     ivgen = qcrypto_ivgen_new(ivalg,
 500                               ivcipheralg,
 501                               ivhash,
 502                               possiblekey, masterkeylen,
 503                               errp);
 504     if (!ivgen) {
 505         goto cleanup;
 506     }
 507
 508
 509     /*
 510      * The master key needs to be decrypted in the same
 511      * way that the block device payload will be decrypted
 512      * later. In particular we'll be using the IV generator
 513      * to reset the encryption cipher every time the master
 514      * key crosses a sector boundary.
 515      */
 516     if (qcrypto_block_decrypt_helper(cipher,
 517                                      niv,
 518                                      ivgen,
 519                                      QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 520                                      0,
 521                                      splitkey,
 522                                      splitkeylen,
 523                                      errp) < 0) {
 524         goto cleanup;
 525     }
 526
 527     /*
 528      * Now we've decrypted the split master key, join
 529      * it back together to get the actual master key.
 530      */
 531     if (qcrypto_afsplit_decode(hash,
 532                                masterkeylen,
 533                                slot->stripes,
 534                                splitkey,
 535                                masterkey,
 536                                errp) < 0) {
 537         goto cleanup;
 538     }
 539
 540
 541     /*
 542      * We still don't know that the masterkey we got is valid,
 543      * because we just blindly assumed the user's password
 544      * was correct. This is where we now verify it. We are
 545      * creating a hash of the master key using PBKDF and
 546      * then comparing that to the hash stored in the key slot
 547      * header
 548      */
 549     if (qcrypto_pbkdf2(hash,
 550                        masterkey, masterkeylen,
 551                        luks->header.master_key_salt,
 552                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
 553                        luks->header.master_key_iterations,
 554                        keydigest, G_N_ELEMENTS(keydigest),
 555                        errp) < 0) {
 556         goto cleanup;
 557     }
 558
 559     if (memcmp(keydigest, luks->header.master_key_digest,
 560                QCRYPTO_BLOCK_LUKS_DIGEST_LEN) == 0) {
 561         /* Success, we got the right master key */
 562         ret = 1;
 563         goto cleanup;
 564     }
 565
 566     /* Fail, user's password was not valid for this key slot,
 567      * tell caller to try another slot */
 568     ret = 0;
 569
 570  cleanup:
 571     qcrypto_ivgen_free(ivgen);
 572     qcrypto_cipher_free(cipher);
 573     g_free(splitkey);
 574     g_free(possiblekey);
 575     return ret;
 576 }
 577
 578
 579 /*
 580  * Given a user password, this will iterate over all key
 581  * slots and try to unlock each active key slot using the
 582  * password until it successfully obtains a master key.
 583  *
 584  * Returns 0 if a key was loaded, -1 if no keys could be loaded
 585  */
 586 static int
 587 qcrypto_block_luks_find_key(QCryptoBlock *block,
 588                             const char *password,
 589                             QCryptoCipherAlgorithm cipheralg,
 590                             QCryptoCipherMode ciphermode,
 591                             QCryptoHashAlgorithm hash,
 592                             QCryptoIVGenAlgorithm ivalg,
 593                             QCryptoCipherAlgorithm ivcipheralg,
 594                             QCryptoHashAlgorithm ivhash,
 595                             uint8_t **masterkey,
 596                             size_t *masterkeylen,
 597                             QCryptoBlockReadFunc readfunc,
 598                             void *opaque,
 599                             Error **errp)
 600 {
 601     QCryptoBlockLUKS *luks = block->opaque;
 602     size_t i;
 603     int rv;
 604
 605     *masterkey = g_new0(uint8_t, luks->header.key_bytes);
 606     *masterkeylen = luks->header.key_bytes;
 607
 608     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
 609         rv = qcrypto_block_luks_load_key(block,
 610                                          &luks->header.key_slots[i],
 611                                          password,
 612                                          cipheralg,
 613                                          ciphermode,
 614                                          hash,
 615                                          ivalg,
 616                                          ivcipheralg,
 617                                          ivhash,
 618                                          *masterkey,
 619                                          *masterkeylen,
 620                                          readfunc,
 621                                          opaque,
 622                                          errp);
 623         if (rv < 0) {
 624             goto error;
 625         }
 626         if (rv == 1) {
 627             return 0;
 628         }
 629     }
 630
 631     error_setg(errp, "Invalid password, cannot unlock any keyslot");
 632
 633  error:
 634     g_free(*masterkey);
 635     *masterkey = NULL;
 636     *masterkeylen = 0;
 637     return -1;
 638 }
 639
 640
 641 static int
 642 qcrypto_block_luks_open(QCryptoBlock *block,
 643                         QCryptoBlockOpenOptions *options,
 644                         QCryptoBlockReadFunc readfunc,
 645                         void *opaque,
 646                         unsigned int flags,
 647                         Error **errp)
 648 {
 649     QCryptoBlockLUKS *luks;
 650     Error *local_err = NULL;
 651     int ret = 0;
 652     size_t i;
 653     ssize_t rv;
 654     uint8_t *masterkey = NULL;
 655     size_t masterkeylen;
 656     char *ivgen_name, *ivhash_name;
 657     QCryptoCipherMode ciphermode;
 658     QCryptoCipherAlgorithm cipheralg;
 659     QCryptoIVGenAlgorithm ivalg;
 660     QCryptoCipherAlgorithm ivcipheralg;
 661     QCryptoHashAlgorithm hash;
 662     QCryptoHashAlgorithm ivhash;
 663     char *password = NULL;
 664
 665     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
 666         if (!options->u.luks.key_secret) {
 667             error_setg(errp, "Parameter 'key-secret' is required for cipher");
 668             return -1;
 669         }
 670         password = qcrypto_secret_lookup_as_utf8(
 671             options->u.luks.key_secret, errp);
 672         if (!password) {
 673             return -1;
 674         }
 675     }
 676
 677     luks = g_new0(QCryptoBlockLUKS, 1);
 678     block->opaque = luks;
 679
 680     /* Read the entire LUKS header, minus the key material from
 681      * the underlying device */
 682     rv = readfunc(block, 0,
 683                   (uint8_t *)&luks->header,
 684                   sizeof(luks->header),
 685                   errp,
 686                   opaque);
 687     if (rv < 0) {
 688         ret = rv;
 689         goto fail;
 690     }
 691
 692     /* The header is always stored in big-endian format, so
 693      * convert everything to native */
 694     be16_to_cpus(&luks->header.version);
 695     be32_to_cpus(&luks->header.payload_offset);
 696     be32_to_cpus(&luks->header.key_bytes);
 697     be32_to_cpus(&luks->header.master_key_iterations);
 698
 699     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
 700         be32_to_cpus(&luks->header.key_slots[i].active);
 701         be32_to_cpus(&luks->header.key_slots[i].iterations);
 702         be32_to_cpus(&luks->header.key_slots[i].key_offset);
 703         be32_to_cpus(&luks->header.key_slots[i].stripes);
 704     }
 705
 706     if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
 707                QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
 708         error_setg(errp, "Volume is not in LUKS format");
 709         ret = -EINVAL;
 710         goto fail;
 711     }
 712     if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
 713         error_setg(errp, "LUKS version %" PRIu32 " is not supported",
 714                    luks->header.version);
 715         ret = -ENOTSUP;
 716         goto fail;
 717     }
 718
 719     /*
 720      * The cipher_mode header contains a string that we have
 721      * to further parse, of the format
 722      *
 723      *    <cipher-mode>-<iv-generator>[:<iv-hash>]
 724      *
 725      * eg  cbc-essiv:sha256, cbc-plain64
 726      */
 727     ivgen_name = strchr(luks->header.cipher_mode, '-');
 728     if (!ivgen_name) {
 729         ret = -EINVAL;
 730         error_setg(errp, "Unexpected cipher mode string format %s",
 731                    luks->header.cipher_mode);
 732         goto fail;
 733     }
 734     *ivgen_name = '\0';
 735     ivgen_name++;
 736
 737     ivhash_name = strchr(ivgen_name, ':');
 738     if (!ivhash_name) {
 739         ivhash = 0;
 740     } else {
 741         *ivhash_name = '\0';
 742         ivhash_name++;
 743
 744         ivhash = qcrypto_block_luks_hash_name_lookup(ivhash_name,
 745                                                      &local_err);
 746         if (local_err) {
 747             ret = -ENOTSUP;
 748             error_propagate(errp, local_err);
 749             goto fail;
 750         }
 751     }
 752
 753     ciphermode = qcrypto_block_luks_cipher_mode_lookup(luks->header.cipher_mode,
 754                                                        &local_err);
 755     if (local_err) {
 756         ret = -ENOTSUP;
 757         error_propagate(errp, local_err);
 758         goto fail;
 759     }
 760
 761     cipheralg = qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
 762                                                       ciphermode,
 763                                                       luks->header.key_bytes,
 764                                                       &local_err);
 765     if (local_err) {
 766         ret = -ENOTSUP;
 767         error_propagate(errp, local_err);
 768         goto fail;
 769     }
 770
 771     hash = qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
 772                                                &local_err);
 773     if (local_err) {
 774         ret = -ENOTSUP;
 775         error_propagate(errp, local_err);
 776         goto fail;
 777     }
 778
 779     ivalg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
 780                                                  &local_err);
 781     if (local_err) {
 782         ret = -ENOTSUP;
 783         error_propagate(errp, local_err);
 784         goto fail;
 785     }
 786
 787     if (ivalg == QCRYPTO_IVGEN_ALG_ESSIV) {
 788         if (!ivhash_name) {
 789             ret = -EINVAL;
 790             error_setg(errp, "Missing IV generator hash specification");
 791             goto fail;
 792         }
 793         ivcipheralg = qcrypto_block_luks_essiv_cipher(cipheralg,
 794                                                       ivhash,
 795                                                       &local_err);
 796         if (local_err) {
 797             ret = -ENOTSUP;
 798             error_propagate(errp, local_err);
 799             goto fail;
 800         }
 801     } else {
 802         /* Note we parsed the ivhash_name earlier in the cipher_mode
 803          * spec string even with plain/plain64 ivgens, but we
 804          * will ignore it, since it is irrelevant for these ivgens.
 805          * This is for compat with dm-crypt which will silently
 806          * ignore hash names with these ivgens rather than report
 807          * an error about the invalid usage
 808          */
 809         ivcipheralg = cipheralg;
 810     }
 811
 812     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
 813         /* Try to find which key slot our password is valid for
 814          * and unlock the master key from that slot.
 815          */
 816         if (qcrypto_block_luks_find_key(block,
 817                                         password,
 818                                         cipheralg, ciphermode,
 819                                         hash,
 820                                         ivalg,
 821                                         ivcipheralg,
 822                                         ivhash,
 823                                         &masterkey, &masterkeylen,
 824                                         readfunc, opaque,
 825                                         errp) < 0) {
 826             ret = -EACCES;
 827             goto fail;
 828         }
 829
 830         /* We have a valid master key now, so can setup the
 831          * block device payload decryption objects
 832          */
 833         block->kdfhash = hash;
 834         block->niv = qcrypto_cipher_get_iv_len(cipheralg,
 835                                                ciphermode);
 836         block->ivgen = qcrypto_ivgen_new(ivalg,
 837                                          ivcipheralg,
 838                                          ivhash,
 839                                          masterkey, masterkeylen,
 840                                          errp);
 841         if (!block->ivgen) {
 842             ret = -ENOTSUP;
 843             goto fail;
 844         }
 845
 846         block->cipher = qcrypto_cipher_new(cipheralg,
 847                                            ciphermode,
 848                                            masterkey, masterkeylen,
 849                                            errp);
 850         if (!block->cipher) {
 851             ret = -ENOTSUP;
 852             goto fail;
 853         }
 854     }
 855
 856     block->payload_offset = luks->header.payload_offset *
 857         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
 858
 859     luks->cipher_alg = cipheralg;
 860     luks->cipher_mode = ciphermode;
 861     luks->ivgen_alg = ivalg;
 862     luks->ivgen_hash_alg = ivhash;
 863     luks->hash_alg = hash;
 864
 865     g_free(masterkey);
 866     g_free(password);
 867
 868     return 0;
 869
 870  fail:
 871     g_free(masterkey);
 872     qcrypto_cipher_free(block->cipher);
 873     qcrypto_ivgen_free(block->ivgen);
 874     g_free(luks);
 875     g_free(password);
 876     return ret;
 877 }
 878
 879
 880 static int
 881 qcrypto_block_luks_uuid_gen(uint8_t *uuidstr, Error **errp)
 882 {
 883 #ifdef CONFIG_UUID
 884     uuid_t uuid;
 885     uuid_generate(uuid);
 886     uuid_unparse(uuid, (char *)uuidstr);
 887     return 0;
 888 #else
 889     error_setg(errp, "Unable to generate uuids on this platform");
 890     return -1;
 891 #endif
 892 }
 893
 894 static int
 895 qcrypto_block_luks_create(QCryptoBlock *block,
 896                           QCryptoBlockCreateOptions *options,
 897                           QCryptoBlockInitFunc initfunc,
 898                           QCryptoBlockWriteFunc writefunc,
 899                           void *opaque,
 900                           Error **errp)
 901 {
 902     QCryptoBlockLUKS *luks;
 903     QCryptoBlockCreateOptionsLUKS luks_opts;
 904     Error *local_err = NULL;
 905     uint8_t *masterkey = NULL;
 906     uint8_t *slotkey = NULL;
 907     uint8_t *splitkey = NULL;
 908     size_t splitkeylen = 0;
 909     size_t i;
 910     QCryptoCipher *cipher = NULL;
 911     QCryptoIVGen *ivgen = NULL;
 912     char *password;
 913     const char *cipher_alg;
 914     const char *cipher_mode;
 915     const char *ivgen_alg;
 916     const char *ivgen_hash_alg = NULL;
 917     const char *hash_alg;
 918     char *cipher_mode_spec = NULL;
 919     QCryptoCipherAlgorithm ivcipheralg = 0;
 920     uint64_t iters;
 921
 922     memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
 923     if (!luks_opts.has_iter_time) {
 924         luks_opts.iter_time = 2000;
 925     }
 926     if (!luks_opts.has_cipher_alg) {
 927         luks_opts.cipher_alg = QCRYPTO_CIPHER_ALG_AES_256;
 928     }
 929     if (!luks_opts.has_cipher_mode) {
 930         luks_opts.cipher_mode = QCRYPTO_CIPHER_MODE_XTS;
 931     }
 932     if (!luks_opts.has_ivgen_alg) {
 933         luks_opts.ivgen_alg = QCRYPTO_IVGEN_ALG_PLAIN64;
 934     }
 935     if (!luks_opts.has_hash_alg) {
 936         luks_opts.hash_alg = QCRYPTO_HASH_ALG_SHA256;
 937     }
 938     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
 939         if (!luks_opts.has_ivgen_hash_alg) {
 940             luks_opts.ivgen_hash_alg = QCRYPTO_HASH_ALG_SHA256;
 941             luks_opts.has_ivgen_hash_alg = true;
 942         }
 943     }
 944     /* Note we're allowing ivgen_hash_alg to be set even for
 945      * non-essiv iv generators that don't need a hash. It will
 946      * be silently ignored, for compatibility with dm-crypt */
 947
 948     if (!options->u.luks.key_secret) {
 949         error_setg(errp, "Parameter 'key-secret' is required for cipher");
 950         return -1;
 951     }
 952     password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret, errp);
 953     if (!password) {
 954         return -1;
 955     }
 956
 957     luks = g_new0(QCryptoBlockLUKS, 1);
 958     block->opaque = luks;
 959
 960     memcpy(luks->header.magic, qcrypto_block_luks_magic,
 961            QCRYPTO_BLOCK_LUKS_MAGIC_LEN);
 962
 963     /* We populate the header in native endianness initially and
 964      * then convert everything to big endian just before writing
 965      * it out to disk
 966      */
 967     luks->header.version = QCRYPTO_BLOCK_LUKS_VERSION;
 968     if (qcrypto_block_luks_uuid_gen(luks->header.uuid,
 969                                     errp) < 0) {
 970         goto error;
 971     }
 972
 973     cipher_alg = qcrypto_block_luks_cipher_alg_lookup(luks_opts.cipher_alg,
 974                                                       errp);
 975     if (!cipher_alg) {
 976         goto error;
 977     }
 978
 979     cipher_mode = QCryptoCipherMode_lookup[luks_opts.cipher_mode];
 980     ivgen_alg = QCryptoIVGenAlgorithm_lookup[luks_opts.ivgen_alg];
 981     if (luks_opts.has_ivgen_hash_alg) {
 982         ivgen_hash_alg = QCryptoHashAlgorithm_lookup[luks_opts.ivgen_hash_alg];
 983         cipher_mode_spec = g_strdup_printf("%s-%s:%s", cipher_mode, ivgen_alg,
 984                                            ivgen_hash_alg);
 985     } else {
 986         cipher_mode_spec = g_strdup_printf("%s-%s", cipher_mode, ivgen_alg);
 987     }
 988     hash_alg = QCryptoHashAlgorithm_lookup[luks_opts.hash_alg];
 989
 990
 991     if (strlen(cipher_alg) >= QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN) {
 992         error_setg(errp, "Cipher name '%s' is too long for LUKS header",
 993                    cipher_alg);
 994         goto error;
 995     }
 996     if (strlen(cipher_mode_spec) >= QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN) {
 997         error_setg(errp, "Cipher mode '%s' is too long for LUKS header",
 998                    cipher_mode_spec);
 999         goto error;
1000     }
1001     if (strlen(hash_alg) >= QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN) {
1002         error_setg(errp, "Hash name '%s' is too long for LUKS header",
1003                    hash_alg);
1004         goto error;
1005     }
1006
1007     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1008         ivcipheralg = qcrypto_block_luks_essiv_cipher(luks_opts.cipher_alg,
1009                                                       luks_opts.ivgen_hash_alg,
1010                                                       &local_err);
1011         if (local_err) {
1012             error_propagate(errp, local_err);
1013             goto error;
1014         }
1015     } else {
1016         ivcipheralg = luks_opts.cipher_alg;
1017     }
1018
1019     strcpy(luks->header.cipher_name, cipher_alg);
1020     strcpy(luks->header.cipher_mode, cipher_mode_spec);
1021     strcpy(luks->header.hash_spec, hash_alg);
1022
1023     luks->header.key_bytes = qcrypto_cipher_get_key_len(luks_opts.cipher_alg);
1024     if (luks_opts.cipher_mode == QCRYPTO_CIPHER_MODE_XTS) {
1025         luks->header.key_bytes *= 2;
1026     }
1027
1028     /* Generate the salt used for hashing the master key
1029      * with PBKDF later
1030      */
1031     if (qcrypto_random_bytes(luks->header.master_key_salt,
1032                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1033                              errp) < 0) {
1034         goto error;
1035     }
1036
1037     /* Generate random master key */
1038     masterkey = g_new0(uint8_t, luks->header.key_bytes);
1039     if (qcrypto_random_bytes(masterkey,
1040                              luks->header.key_bytes, errp) < 0) {
1041         goto error;
1042     }
1043
1044
1045     /* Setup the block device payload encryption objects */
1046     block->cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
1047                                        luks_opts.cipher_mode,
1048                                        masterkey, luks->header.key_bytes,
1049                                        errp);
1050     if (!block->cipher) {
1051         goto error;
1052     }
1053
1054     block->kdfhash = luks_opts.hash_alg;
1055     block->niv = qcrypto_cipher_get_iv_len(luks_opts.cipher_alg,
1056                                            luks_opts.cipher_mode);
1057     block->ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1058                                      ivcipheralg,
1059                                      luks_opts.ivgen_hash_alg,
1060                                      masterkey, luks->header.key_bytes,
1061                                      errp);
1062
1063     if (!block->ivgen) {
1064         goto error;
1065     }
1066
1067
1068     /* Determine how many iterations we need to hash the master
1069      * key, in order to have 1 second of compute time used
1070      */
1071     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1072                                        masterkey, luks->header.key_bytes,
1073                                        luks->header.master_key_salt,
1074                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1075                                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1076                                        &local_err);
1077     if (local_err) {
1078         error_propagate(errp, local_err);
1079         goto error;
1080     }
1081
1082     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1083         error_setg_errno(errp, ERANGE,
1084                          "PBKDF iterations %llu too large to scale",
1085                          (unsigned long long)iters);
1086         goto error;
1087     }
1088
1089     /* iter_time was in millis, but count_iters reported for secs */
1090     iters = iters * luks_opts.iter_time / 1000;
1091
1092     /* Why /= 8 ?  That matches cryptsetup, but there's no
1093      * explanation why they chose /= 8... Probably so that
1094      * if all 8 keyslots are active we only spend 1 second
1095      * in total time to check all keys */
1096     iters /= 8;
1097     if (iters > UINT32_MAX) {
1098         error_setg_errno(errp, ERANGE,
1099                          "PBKDF iterations %llu larger than %u",
1100                          (unsigned long long)iters, UINT32_MAX);
1101         goto error;
1102     }
1103     iters = MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS);
1104     luks->header.master_key_iterations = iters;
1105
1106     /* Hash the master key, saving the result in the LUKS
1107      * header. This hash is used when opening the encrypted
1108      * device to verify that the user password unlocked a
1109      * valid master key
1110      */
1111     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1112                        masterkey, luks->header.key_bytes,
1113                        luks->header.master_key_salt,
1114                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1115                        luks->header.master_key_iterations,
1116                        luks->header.master_key_digest,
1117                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1118                        errp) < 0) {
1119         goto error;
1120     }
1121
1122
1123     /* Although LUKS has multiple key slots, we're just going
1124      * to use the first key slot */
1125     splitkeylen = luks->header.key_bytes * QCRYPTO_BLOCK_LUKS_STRIPES;
1126     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1127         luks->header.key_slots[i].active = i == 0 ?
1128             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED :
1129             QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
1130         luks->header.key_slots[i].stripes = QCRYPTO_BLOCK_LUKS_STRIPES;
1131
1132         /* This calculation doesn't match that shown in the spec,
1133          * but instead follows the cryptsetup implementation.
1134          */
1135         luks->header.key_slots[i].key_offset =
1136             (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1137              QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1138             (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1139                       (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1140                        QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) * i);
1141     }
1142
1143     if (qcrypto_random_bytes(luks->header.key_slots[0].salt,
1144                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1145                              errp) < 0) {
1146         goto error;
1147     }
1148
1149     /* Again we determine how many iterations are required to
1150      * hash the user password while consuming 1 second of compute
1151      * time */
1152     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1153                                        (uint8_t *)password, strlen(password),
1154                                        luks->header.key_slots[0].salt,
1155                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1156                                        luks->header.key_bytes,
1157                                        &local_err);
1158     if (local_err) {
1159         error_propagate(errp, local_err);
1160         goto error;
1161     }
1162
1163     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1164         error_setg_errno(errp, ERANGE,
1165                          "PBKDF iterations %llu too large to scale",
1166                          (unsigned long long)iters);
1167         goto error;
1168     }
1169
1170     /* iter_time was in millis, but count_iters reported for secs */
1171     iters = iters * luks_opts.iter_time / 1000;
1172
1173     if (iters > UINT32_MAX) {
1174         error_setg_errno(errp, ERANGE,
1175                          "PBKDF iterations %llu larger than %u",
1176                          (unsigned long long)iters, UINT32_MAX);
1177         goto error;
1178     }
1179
1180     luks->header.key_slots[0].iterations =
1181         MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);
1182
1183
1184     /* Generate a key that we'll use to encrypt the master
1185      * key, from the user's password
1186      */
1187     slotkey = g_new0(uint8_t, luks->header.key_bytes);
1188     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1189                        (uint8_t *)password, strlen(password),
1190                        luks->header.key_slots[0].salt,
1191                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1192                        luks->header.key_slots[0].iterations,
1193                        slotkey, luks->header.key_bytes,
1194                        errp) < 0) {
1195         goto error;
1196     }
1197
1198
1199     /* Setup the encryption objects needed to encrypt the
1200      * master key material
1201      */
1202     cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
1203                                 luks_opts.cipher_mode,
1204                                 slotkey, luks->header.key_bytes,
1205                                 errp);
1206     if (!cipher) {
1207         goto error;
1208     }
1209
1210     ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1211                               ivcipheralg,
1212                               luks_opts.ivgen_hash_alg,
1213                               slotkey, luks->header.key_bytes,
1214                               errp);
1215     if (!ivgen) {
1216         goto error;
1217     }
1218
1219     /* Before storing the master key, we need to vastly
1220      * increase its size, as protection against forensic
1221      * disk data recovery */
1222     splitkey = g_new0(uint8_t, splitkeylen);
1223
1224     if (qcrypto_afsplit_encode(luks_opts.hash_alg,
1225                                luks->header.key_bytes,
1226                                luks->header.key_slots[0].stripes,
1227                                masterkey,
1228                                splitkey,
1229                                errp) < 0) {
1230         goto error;
1231     }
1232
1233     /* Now we encrypt the split master key with the key generated
1234      * from the user's password, before storing it */
1235     if (qcrypto_block_encrypt_helper(cipher, block->niv, ivgen,
1236                                      QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1237                                      0,
1238                                      splitkey,
1239                                      splitkeylen,
1240                                      errp) < 0) {
1241         goto error;
1242     }
1243
1244
1245     /* The total size of the LUKS headers is the partition header + key
1246      * slot headers, rounded up to the nearest sector, combined with
1247      * the size of each master key material region, also rounded up
1248      * to the nearest sector */
1249     luks->header.payload_offset =
1250         (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1251          QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
1252         (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
1253                   (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1254                    QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) *
1255          QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
1256
1257     block->payload_offset = luks->header.payload_offset *
1258         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1259
1260     /* Reserve header space to match payload offset */
1261     initfunc(block, block->payload_offset, &local_err, opaque);
1262     if (local_err) {
1263         error_propagate(errp, local_err);
1264         goto error;
1265     }
1266
1267     /* Everything on disk uses Big Endian, so flip header fields
1268      * before writing them */
1269     cpu_to_be16s(&luks->header.version);
1270     cpu_to_be32s(&luks->header.payload_offset);
1271     cpu_to_be32s(&luks->header.key_bytes);
1272     cpu_to_be32s(&luks->header.master_key_iterations);
1273
1274     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1275         cpu_to_be32s(&luks->header.key_slots[i].active);
1276         cpu_to_be32s(&luks->header.key_slots[i].iterations);
1277         cpu_to_be32s(&luks->header.key_slots[i].key_offset);
1278         cpu_to_be32s(&luks->header.key_slots[i].stripes);
1279     }
1280
1281
1282     /* Write out the partition header and key slot headers */
1283     writefunc(block, 0,
1284               (const uint8_t *)&luks->header,
1285               sizeof(luks->header),
1286               &local_err,
1287               opaque);
1288
1289     /* Delay checking local_err until we've byte-swapped */
1290
1291     /* Byte swap the header back to native, in case we need
1292      * to read it again later */
1293     be16_to_cpus(&luks->header.version);
1294     be32_to_cpus(&luks->header.payload_offset);
1295     be32_to_cpus(&luks->header.key_bytes);
1296     be32_to_cpus(&luks->header.master_key_iterations);
1297
1298     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1299         be32_to_cpus(&luks->header.key_slots[i].active);
1300         be32_to_cpus(&luks->header.key_slots[i].iterations);
1301         be32_to_cpus(&luks->header.key_slots[i].key_offset);
1302         be32_to_cpus(&luks->header.key_slots[i].stripes);
1303     }
1304
1305     if (local_err) {
1306         error_propagate(errp, local_err);
1307         goto error;
1308     }
1309
1310     /* Write out the master key material, starting at the
1311      * sector immediately following the partition header. */
1312     if (writefunc(block,
1313                   luks->header.key_slots[0].key_offset *
1314                   QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1315                   splitkey, splitkeylen,
1316                   errp,
1317                   opaque) != splitkeylen) {
1318         goto error;
1319     }
1320
1321     luks->cipher_alg = luks_opts.cipher_alg;
1322     luks->cipher_mode = luks_opts.cipher_mode;
1323     luks->ivgen_alg = luks_opts.ivgen_alg;
1324     luks->ivgen_hash_alg = luks_opts.ivgen_hash_alg;
1325     luks->hash_alg = luks_opts.hash_alg;
1326
1327     memset(masterkey, 0, luks->header.key_bytes);
1328     g_free(masterkey);
1329     memset(slotkey, 0, luks->header.key_bytes);
1330     g_free(slotkey);
1331     g_free(splitkey);
1332     g_free(password);
1333     g_free(cipher_mode_spec);
1334
1335     qcrypto_ivgen_free(ivgen);
1336     qcrypto_cipher_free(cipher);
1337
1338     return 0;
1339
1340  error:
1341     if (masterkey) {
1342         memset(masterkey, 0, luks->header.key_bytes);
1343     }
1344     g_free(masterkey);
1345     if (slotkey) {
1346         memset(slotkey, 0, luks->header.key_bytes);
1347     }
1348     g_free(slotkey);
1349     g_free(splitkey);
1350     g_free(password);
1351     g_free(cipher_mode_spec);
1352
1353     qcrypto_ivgen_free(ivgen);
1354     qcrypto_cipher_free(cipher);
1355
1356     g_free(luks);
1357     return -1;
1358 }
1359
1360
1361 static int qcrypto_block_luks_get_info(QCryptoBlock *block,
1362                                        QCryptoBlockInfo *info,
1363                                        Error **errp)
1364 {
1365     QCryptoBlockLUKS *luks = block->opaque;
1366     QCryptoBlockInfoLUKSSlot *slot;
1367     QCryptoBlockInfoLUKSSlotList *slots = NULL, **prev = &info->u.luks.slots;
1368     size_t i;
1369
1370     info->u.luks.cipher_alg = luks->cipher_alg;
1371     info->u.luks.cipher_mode = luks->cipher_mode;
1372     info->u.luks.ivgen_alg = luks->ivgen_alg;
1373     if (info->u.luks.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1374         info->u.luks.has_ivgen_hash_alg = true;
1375         info->u.luks.ivgen_hash_alg = luks->ivgen_hash_alg;
1376     }
1377     info->u.luks.hash_alg = luks->hash_alg;
1378     info->u.luks.payload_offset = block->payload_offset;
1379     info->u.luks.master_key_iters = luks->header.master_key_iterations;
1380     info->u.luks.uuid = g_strndup((const char *)luks->header.uuid,
1381                                   sizeof(luks->header.uuid));
1382
1383     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1384         slots = g_new0(QCryptoBlockInfoLUKSSlotList, 1);
1385         *prev = slots;
1386
1387         slots->value = slot = g_new0(QCryptoBlockInfoLUKSSlot, 1);
1388         slot->active = luks->header.key_slots[i].active ==
1389             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
1390         slot->key_offset = luks->header.key_slots[i].key_offset
1391              * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1392         if (slot->active) {
1393             slot->has_iters = true;
1394             slot->iters = luks->header.key_slots[i].iterations;
1395             slot->has_stripes = true;
1396             slot->stripes = luks->header.key_slots[i].stripes;
1397         }
1398
1399         prev = &slots->next;
1400     }
1401
1402     return 0;
1403 }
1404
1405
1406 static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
1407 {
1408     g_free(block->opaque);
1409 }
1410
1411
1412 static int
1413 qcrypto_block_luks_decrypt(QCryptoBlock *block,
1414                            uint64_t startsector,
1415                            uint8_t *buf,
1416                            size_t len,
1417                            Error **errp)
1418 {
1419     return qcrypto_block_decrypt_helper(block->cipher,
1420                                         block->niv, block->ivgen,
1421                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1422                                         startsector, buf, len, errp);
1423 }
1424
1425
1426 static int
1427 qcrypto_block_luks_encrypt(QCryptoBlock *block,
1428                            uint64_t startsector,
1429                            uint8_t *buf,
1430                            size_t len,
1431                            Error **errp)
1432 {
1433     return qcrypto_block_encrypt_helper(block->cipher,
1434                                         block->niv, block->ivgen,
1435                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1436                                         startsector, buf, len, errp);
1437 }
1438
1439
1440 const QCryptoBlockDriver qcrypto_block_driver_luks = {
1441     .open = qcrypto_block_luks_open,
1442     .create = qcrypto_block_luks_create,
1443     .get_info = qcrypto_block_luks_get_info,
1444     .cleanup = qcrypto_block_luks_cleanup,
1445     .decrypt = qcrypto_block_luks_decrypt,
1446     .encrypt = qcrypto_block_luks_encrypt,
1447     .has_format = qcrypto_block_luks_has_format,
1448 };