crypto/block-luks.c

   1 /*
   2  * QEMU Crypto block device encryption LUKS format
   3  *
   4  * Copyright (c) 2015-2016 Red Hat, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "qapi/error.h"
  23 #include "qemu/bswap.h"
  24
  25 #include "block-luks.h"
  26
  27 #include "crypto/hash.h"
  28 #include "crypto/afsplit.h"
  29 #include "crypto/pbkdf.h"
  30 #include "crypto/secret.h"
  31 #include "crypto/random.h"
  32 #include "qemu/uuid.h"
  33
  34 #include "qemu/coroutine.h"
  35
  36 /*
  37  * Reference for the LUKS format implemented here is
  38  *
  39  *   docs/on-disk-format.pdf
  40  *
  41  * in 'cryptsetup' package source code
  42  *
  43  * This file implements the 1.2.1 specification, dated
  44  * Oct 16, 2011.
  45  */
  46
  47 typedef struct QCryptoBlockLUKS QCryptoBlockLUKS;
  48 typedef struct QCryptoBlockLUKSHeader QCryptoBlockLUKSHeader;
  49 typedef struct QCryptoBlockLUKSKeySlot QCryptoBlockLUKSKeySlot;
  50
  51
  52 /* The following constants are all defined by the LUKS spec */
  53 #define QCRYPTO_BLOCK_LUKS_VERSION 1
  54
  55 #define QCRYPTO_BLOCK_LUKS_MAGIC_LEN 6
  56 #define QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN 32
  57 #define QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN 32
  58 #define QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN 32
  59 #define QCRYPTO_BLOCK_LUKS_DIGEST_LEN 20
  60 #define QCRYPTO_BLOCK_LUKS_SALT_LEN 32
  61 #define QCRYPTO_BLOCK_LUKS_UUID_LEN 40
  62 #define QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS 8
  63 #define QCRYPTO_BLOCK_LUKS_STRIPES 4000
  64 #define QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS 1000
  65 #define QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS 1000
  66 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET 4096
  67
  68 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED 0x0000DEAD
  69 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED 0x00AC71F3
  70
  71 #define QCRYPTO_BLOCK_LUKS_SECTOR_SIZE 512LL
  72
  73 static const char qcrypto_block_luks_magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN] = {
  74     'L', 'U', 'K', 'S', 0xBA, 0xBE
  75 };
  76
  77 typedef struct QCryptoBlockLUKSNameMap QCryptoBlockLUKSNameMap;
  78 struct QCryptoBlockLUKSNameMap {
  79     const char *name;
  80     int id;
  81 };
  82
  83 typedef struct QCryptoBlockLUKSCipherSizeMap QCryptoBlockLUKSCipherSizeMap;
  84 struct QCryptoBlockLUKSCipherSizeMap {
  85     uint32_t key_bytes;
  86     int id;
  87 };
  88 typedef struct QCryptoBlockLUKSCipherNameMap QCryptoBlockLUKSCipherNameMap;
  89 struct QCryptoBlockLUKSCipherNameMap {
  90     const char *name;
  91     const QCryptoBlockLUKSCipherSizeMap *sizes;
  92 };
  93
  94
  95 static const QCryptoBlockLUKSCipherSizeMap
  96 qcrypto_block_luks_cipher_size_map_aes[] = {
  97     { 16, QCRYPTO_CIPHER_ALG_AES_128 },
  98     { 24, QCRYPTO_CIPHER_ALG_AES_192 },
  99     { 32, QCRYPTO_CIPHER_ALG_AES_256 },
 100     { 0, 0 },
 101 };
 102
 103 static const QCryptoBlockLUKSCipherSizeMap
 104 qcrypto_block_luks_cipher_size_map_cast5[] = {
 105     { 16, QCRYPTO_CIPHER_ALG_CAST5_128 },
 106     { 0, 0 },
 107 };
 108
 109 static const QCryptoBlockLUKSCipherSizeMap
 110 qcrypto_block_luks_cipher_size_map_serpent[] = {
 111     { 16, QCRYPTO_CIPHER_ALG_SERPENT_128 },
 112     { 24, QCRYPTO_CIPHER_ALG_SERPENT_192 },
 113     { 32, QCRYPTO_CIPHER_ALG_SERPENT_256 },
 114     { 0, 0 },
 115 };
 116
 117 static const QCryptoBlockLUKSCipherSizeMap
 118 qcrypto_block_luks_cipher_size_map_twofish[] = {
 119     { 16, QCRYPTO_CIPHER_ALG_TWOFISH_128 },
 120     { 24, QCRYPTO_CIPHER_ALG_TWOFISH_192 },
 121     { 32, QCRYPTO_CIPHER_ALG_TWOFISH_256 },
 122     { 0, 0 },
 123 };
 124
 125 static const QCryptoBlockLUKSCipherNameMap
 126 qcrypto_block_luks_cipher_name_map[] = {
 127     { "aes", qcrypto_block_luks_cipher_size_map_aes },
 128     { "cast5", qcrypto_block_luks_cipher_size_map_cast5 },
 129     { "serpent", qcrypto_block_luks_cipher_size_map_serpent },
 130     { "twofish", qcrypto_block_luks_cipher_size_map_twofish },
 131 };
 132
 133
 134 /*
 135  * This struct is written to disk in big-endian format,
 136  * but operated upon in native-endian format.
 137  */
 138 struct QCryptoBlockLUKSKeySlot {
 139     /* state of keyslot, enabled/disable */
 140     uint32_t active;
 141     /* iterations for PBKDF2 */
 142     uint32_t iterations;
 143     /* salt for PBKDF2 */
 144     uint8_t salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
 145     /* start sector of key material */
 146     uint32_t key_offset_sector;
 147     /* number of anti-forensic stripes */
 148     uint32_t stripes;
 149 };
 150
 151 QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSKeySlot) != 48);
 152
 153
 154 /*
 155  * This struct is written to disk in big-endian format,
 156  * but operated upon in native-endian format.
 157  */
 158 struct QCryptoBlockLUKSHeader {
 159     /* 'L', 'U', 'K', 'S', '0xBA', '0xBE' */
 160     char magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN];
 161
 162     /* LUKS version, currently 1 */
 163     uint16_t version;
 164
 165     /* cipher name specification (aes, etc) */
 166     char cipher_name[QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN];
 167
 168     /* cipher mode specification (cbc-plain, xts-essiv:sha256, etc) */
 169     char cipher_mode[QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN];
 170
 171     /* hash specification (sha256, etc) */
 172     char hash_spec[QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN];
 173
 174     /* start offset of the volume data (in 512 byte sectors) */
 175     uint32_t payload_offset_sector;
 176
 177     /* Number of key bytes */
 178     uint32_t master_key_len;
 179
 180     /* master key checksum after PBKDF2 */
 181     uint8_t master_key_digest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
 182
 183     /* salt for master key PBKDF2 */
 184     uint8_t master_key_salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
 185
 186     /* iterations for master key PBKDF2 */
 187     uint32_t master_key_iterations;
 188
 189     /* UUID of the partition in standard ASCII representation */
 190     uint8_t uuid[QCRYPTO_BLOCK_LUKS_UUID_LEN];
 191
 192     /* key slots */
 193     QCryptoBlockLUKSKeySlot key_slots[QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS];
 194 };
 195
 196 QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSHeader) != 592);
 197
 198
 199 struct QCryptoBlockLUKS {
 200     QCryptoBlockLUKSHeader header;
 201
 202     /* Main encryption algorithm used for encryption*/
 203     QCryptoCipherAlgorithm cipher_alg;
 204
 205     /* Mode of encryption for the selected encryption algorithm */
 206     QCryptoCipherMode cipher_mode;
 207
 208     /* Initialization vector generation algorithm */
 209     QCryptoIVGenAlgorithm ivgen_alg;
 210
 211     /* Hash algorithm used for IV generation*/
 212     QCryptoHashAlgorithm ivgen_hash_alg;
 213
 214     /*
 215      * Encryption algorithm used for IV generation.
 216      * Usually the same as main encryption algorithm
 217      */
 218     QCryptoCipherAlgorithm ivgen_cipher_alg;
 219
 220     /* Hash algorithm used in pbkdf2 function */
 221     QCryptoHashAlgorithm hash_alg;
 222 };
 223
 224
 225 static int qcrypto_block_luks_cipher_name_lookup(const char *name,
 226                                                  QCryptoCipherMode mode,
 227                                                  uint32_t key_bytes,
 228                                                  Error **errp)
 229 {
 230     const QCryptoBlockLUKSCipherNameMap *map =
 231         qcrypto_block_luks_cipher_name_map;
 232     size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
 233     size_t i, j;
 234
 235     if (mode == QCRYPTO_CIPHER_MODE_XTS) {
 236         key_bytes /= 2;
 237     }
 238
 239     for (i = 0; i < maplen; i++) {
 240         if (!g_str_equal(map[i].name, name)) {
 241             continue;
 242         }
 243         for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
 244             if (map[i].sizes[j].key_bytes == key_bytes) {
 245                 return map[i].sizes[j].id;
 246             }
 247         }
 248     }
 249
 250     error_setg(errp, "Algorithm %s with key size %d bytes not supported",
 251                name, key_bytes);
 252     return 0;
 253 }
 254
 255 static const char *
 256 qcrypto_block_luks_cipher_alg_lookup(QCryptoCipherAlgorithm alg,
 257                                      Error **errp)
 258 {
 259     const QCryptoBlockLUKSCipherNameMap *map =
 260         qcrypto_block_luks_cipher_name_map;
 261     size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
 262     size_t i, j;
 263     for (i = 0; i < maplen; i++) {
 264         for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
 265             if (map[i].sizes[j].id == alg) {
 266                 return map[i].name;
 267             }
 268         }
 269     }
 270
 271     error_setg(errp, "Algorithm '%s' not supported",
 272                QCryptoCipherAlgorithm_str(alg));
 273     return NULL;
 274 }
 275
 276 /* XXX replace with qapi_enum_parse() in future, when we can
 277  * make that function emit a more friendly error message */
 278 static int qcrypto_block_luks_name_lookup(const char *name,
 279                                           const QEnumLookup *map,
 280                                           const char *type,
 281                                           Error **errp)
 282 {
 283     int ret = qapi_enum_parse(map, name, -1, NULL);
 284
 285     if (ret < 0) {
 286         error_setg(errp, "%s %s not supported", type, name);
 287         return 0;
 288     }
 289     return ret;
 290 }
 291
 292 #define qcrypto_block_luks_cipher_mode_lookup(name, errp)               \
 293     qcrypto_block_luks_name_lookup(name,                                \
 294                                    &QCryptoCipherMode_lookup,           \
 295                                    "Cipher mode",                       \
 296                                    errp)
 297
 298 #define qcrypto_block_luks_hash_name_lookup(name, errp)                 \
 299     qcrypto_block_luks_name_lookup(name,                                \
 300                                    &QCryptoHashAlgorithm_lookup,        \
 301                                    "Hash algorithm",                    \
 302                                    errp)
 303
 304 #define qcrypto_block_luks_ivgen_name_lookup(name, errp)                \
 305     qcrypto_block_luks_name_lookup(name,                                \
 306                                    &QCryptoIVGenAlgorithm_lookup,       \
 307                                    "IV generator",                      \
 308                                    errp)
 309
 310
 311 static bool
 312 qcrypto_block_luks_has_format(const uint8_t *buf,
 313                               size_t buf_size)
 314 {
 315     const QCryptoBlockLUKSHeader *luks_header = (const void *)buf;
 316
 317     if (buf_size >= offsetof(QCryptoBlockLUKSHeader, cipher_name) &&
 318         memcmp(luks_header->magic, qcrypto_block_luks_magic,
 319                QCRYPTO_BLOCK_LUKS_MAGIC_LEN) == 0 &&
 320         be16_to_cpu(luks_header->version) == QCRYPTO_BLOCK_LUKS_VERSION) {
 321         return true;
 322     } else {
 323         return false;
 324     }
 325 }
 326
 327
 328 /**
 329  * Deal with a quirk of dm-crypt usage of ESSIV.
 330  *
 331  * When calculating ESSIV IVs, the cipher length used by ESSIV
 332  * may be different from the cipher length used for the block
 333  * encryption, becauses dm-crypt uses the hash digest length
 334  * as the key size. ie, if you have AES 128 as the block cipher
 335  * and SHA 256 as ESSIV hash, then ESSIV will use AES 256 as
 336  * the cipher since that gets a key length matching the digest
 337  * size, not AES 128 with truncated digest as might be imagined
 338  */
 339 static QCryptoCipherAlgorithm
 340 qcrypto_block_luks_essiv_cipher(QCryptoCipherAlgorithm cipher,
 341                                 QCryptoHashAlgorithm hash,
 342                                 Error **errp)
 343 {
 344     size_t digestlen = qcrypto_hash_digest_len(hash);
 345     size_t keylen = qcrypto_cipher_get_key_len(cipher);
 346     if (digestlen == keylen) {
 347         return cipher;
 348     }
 349
 350     switch (cipher) {
 351     case QCRYPTO_CIPHER_ALG_AES_128:
 352     case QCRYPTO_CIPHER_ALG_AES_192:
 353     case QCRYPTO_CIPHER_ALG_AES_256:
 354         if (digestlen == qcrypto_cipher_get_key_len(
 355                 QCRYPTO_CIPHER_ALG_AES_128)) {
 356             return QCRYPTO_CIPHER_ALG_AES_128;
 357         } else if (digestlen == qcrypto_cipher_get_key_len(
 358                        QCRYPTO_CIPHER_ALG_AES_192)) {
 359             return QCRYPTO_CIPHER_ALG_AES_192;
 360         } else if (digestlen == qcrypto_cipher_get_key_len(
 361                        QCRYPTO_CIPHER_ALG_AES_256)) {
 362             return QCRYPTO_CIPHER_ALG_AES_256;
 363         } else {
 364             error_setg(errp, "No AES cipher with key size %zu available",
 365                        digestlen);
 366             return 0;
 367         }
 368         break;
 369     case QCRYPTO_CIPHER_ALG_SERPENT_128:
 370     case QCRYPTO_CIPHER_ALG_SERPENT_192:
 371     case QCRYPTO_CIPHER_ALG_SERPENT_256:
 372         if (digestlen == qcrypto_cipher_get_key_len(
 373                 QCRYPTO_CIPHER_ALG_SERPENT_128)) {
 374             return QCRYPTO_CIPHER_ALG_SERPENT_128;
 375         } else if (digestlen == qcrypto_cipher_get_key_len(
 376                        QCRYPTO_CIPHER_ALG_SERPENT_192)) {
 377             return QCRYPTO_CIPHER_ALG_SERPENT_192;
 378         } else if (digestlen == qcrypto_cipher_get_key_len(
 379                        QCRYPTO_CIPHER_ALG_SERPENT_256)) {
 380             return QCRYPTO_CIPHER_ALG_SERPENT_256;
 381         } else {
 382             error_setg(errp, "No Serpent cipher with key size %zu available",
 383                        digestlen);
 384             return 0;
 385         }
 386         break;
 387     case QCRYPTO_CIPHER_ALG_TWOFISH_128:
 388     case QCRYPTO_CIPHER_ALG_TWOFISH_192:
 389     case QCRYPTO_CIPHER_ALG_TWOFISH_256:
 390         if (digestlen == qcrypto_cipher_get_key_len(
 391                 QCRYPTO_CIPHER_ALG_TWOFISH_128)) {
 392             return QCRYPTO_CIPHER_ALG_TWOFISH_128;
 393         } else if (digestlen == qcrypto_cipher_get_key_len(
 394                        QCRYPTO_CIPHER_ALG_TWOFISH_192)) {
 395             return QCRYPTO_CIPHER_ALG_TWOFISH_192;
 396         } else if (digestlen == qcrypto_cipher_get_key_len(
 397                        QCRYPTO_CIPHER_ALG_TWOFISH_256)) {
 398             return QCRYPTO_CIPHER_ALG_TWOFISH_256;
 399         } else {
 400             error_setg(errp, "No Twofish cipher with key size %zu available",
 401                        digestlen);
 402             return 0;
 403         }
 404         break;
 405     default:
 406         error_setg(errp, "Cipher %s not supported with essiv",
 407                    QCryptoCipherAlgorithm_str(cipher));
 408         return 0;
 409     }
 410 }
 411
 412 /*
 413  * Returns number of sectors needed to store the key material
 414  * given number of anti forensic stripes
 415  */
 416 static int
 417 qcrypto_block_luks_splitkeylen_sectors(const QCryptoBlockLUKS *luks,
 418                                        unsigned int header_sectors,
 419                                        unsigned int stripes)
 420 {
 421     /*
 422      * This calculation doesn't match that shown in the spec,
 423      * but instead follows the cryptsetup implementation.
 424      */
 425
 426     size_t splitkeylen = luks->header.master_key_len * stripes;
 427
 428     /* First align the key material size to block size*/
 429     size_t splitkeylen_sectors =
 430         DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE);
 431
 432     /* Then also align the key material size to the size of the header */
 433     return ROUND_UP(splitkeylen_sectors, header_sectors);
 434 }
 435
 436 /*
 437  * Stores the main LUKS header, taking care of endianess
 438  */
 439 static int
 440 qcrypto_block_luks_store_header(QCryptoBlock *block,
 441                                 QCryptoBlockWriteFunc writefunc,
 442                                 void *opaque,
 443                                 Error **errp)
 444 {
 445     const QCryptoBlockLUKS *luks = block->opaque;
 446     Error *local_err = NULL;
 447     size_t i;
 448     g_autofree QCryptoBlockLUKSHeader *hdr_copy = NULL;
 449
 450     /* Create a copy of the header */
 451     hdr_copy = g_new0(QCryptoBlockLUKSHeader, 1);
 452     memcpy(hdr_copy, &luks->header, sizeof(QCryptoBlockLUKSHeader));
 453
 454     /*
 455      * Everything on disk uses Big Endian (tm), so flip header fields
 456      * before writing them
 457      */
 458     cpu_to_be16s(&hdr_copy->version);
 459     cpu_to_be32s(&hdr_copy->payload_offset_sector);
 460     cpu_to_be32s(&hdr_copy->master_key_len);
 461     cpu_to_be32s(&hdr_copy->master_key_iterations);
 462
 463     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
 464         cpu_to_be32s(&hdr_copy->key_slots[i].active);
 465         cpu_to_be32s(&hdr_copy->key_slots[i].iterations);
 466         cpu_to_be32s(&hdr_copy->key_slots[i].key_offset_sector);
 467         cpu_to_be32s(&hdr_copy->key_slots[i].stripes);
 468     }
 469
 470     /* Write out the partition header and key slot headers */
 471     writefunc(block, 0, (const uint8_t *)hdr_copy, sizeof(*hdr_copy),
 472               opaque, &local_err);
 473
 474     if (local_err) {
 475         error_propagate(errp, local_err);
 476         return -1;
 477     }
 478     return 0;
 479 }
 480
 481 /*
 482  * Loads the main LUKS header,and byteswaps it to native endianess
 483  * And run basic sanity checks on it
 484  */
 485 static int
 486 qcrypto_block_luks_load_header(QCryptoBlock *block,
 487                                 QCryptoBlockReadFunc readfunc,
 488                                 void *opaque,
 489                                 Error **errp)
 490 {
 491     ssize_t rv;
 492     size_t i;
 493     QCryptoBlockLUKS *luks = block->opaque;
 494
 495     /*
 496      * Read the entire LUKS header, minus the key material from
 497      * the underlying device
 498      */
 499     rv = readfunc(block, 0,
 500                   (uint8_t *)&luks->header,
 501                   sizeof(luks->header),
 502                   opaque,
 503                   errp);
 504     if (rv < 0) {
 505         return rv;
 506     }
 507
 508     /*
 509      * The header is always stored in big-endian format, so
 510      * convert everything to native
 511      */
 512     be16_to_cpus(&luks->header.version);
 513     be32_to_cpus(&luks->header.payload_offset_sector);
 514     be32_to_cpus(&luks->header.master_key_len);
 515     be32_to_cpus(&luks->header.master_key_iterations);
 516
 517     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
 518         be32_to_cpus(&luks->header.key_slots[i].active);
 519         be32_to_cpus(&luks->header.key_slots[i].iterations);
 520         be32_to_cpus(&luks->header.key_slots[i].key_offset_sector);
 521         be32_to_cpus(&luks->header.key_slots[i].stripes);
 522     }
 523
 524     return 0;
 525 }
 526
 527 /*
 528  * Does basic sanity checks on the LUKS header
 529  */
 530 static int
 531 qcrypto_block_luks_check_header(const QCryptoBlockLUKS *luks, Error **errp)
 532 {
 533     size_t i, j;
 534
 535     unsigned int header_sectors = QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
 536         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
 537
 538     if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
 539                QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
 540         error_setg(errp, "Volume is not in LUKS format");
 541         return -1;
 542     }
 543
 544     if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
 545         error_setg(errp, "LUKS version %" PRIu32 " is not supported",
 546                    luks->header.version);
 547         return -1;
 548     }
 549
 550     /* Check all keyslots for corruption  */
 551     for (i = 0 ; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS ; i++) {
 552
 553         const QCryptoBlockLUKSKeySlot *slot1 = &luks->header.key_slots[i];
 554         unsigned int start1 = slot1->key_offset_sector;
 555         unsigned int len1 =
 556             qcrypto_block_luks_splitkeylen_sectors(luks,
 557                                                    header_sectors,
 558                                                    slot1->stripes);
 559
 560         if (slot1->stripes == 0) {
 561             error_setg(errp, "Keyslot %zu is corrupted (stripes == 0)", i);
 562             return -1;
 563         }
 564
 565         if (slot1->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED &&
 566             slot1->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
 567             error_setg(errp,
 568                        "Keyslot %zu state (active/disable) is corrupted", i);
 569             return -1;
 570         }
 571
 572         if (start1 + len1 > luks->header.payload_offset_sector) {
 573             error_setg(errp,
 574                        "Keyslot %zu is overlapping with the encrypted payload",
 575                        i);
 576             return -1;
 577         }
 578
 579         for (j = i + 1 ; j < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS ; j++) {
 580             const QCryptoBlockLUKSKeySlot *slot2 = &luks->header.key_slots[j];
 581             unsigned int start2 = slot2->key_offset_sector;
 582             unsigned int len2 =
 583                 qcrypto_block_luks_splitkeylen_sectors(luks,
 584                                                        header_sectors,
 585                                                        slot2->stripes);
 586
 587             if (start1 + len1 > start2 && start2 + len2 > start1) {
 588                 error_setg(errp,
 589                            "Keyslots %zu and %zu are overlapping in the header",
 590                            i, j);
 591                 return -1;
 592             }
 593         }
 594
 595     }
 596     return 0;
 597 }
 598
 599 /*
 600  * Parses the crypto parameters that are stored in the LUKS header
 601  */
 602
 603 static int
 604 qcrypto_block_luks_parse_header(QCryptoBlockLUKS *luks, Error **errp)
 605 {
 606     g_autofree char *cipher_mode = g_strdup(luks->header.cipher_mode);
 607     char *ivgen_name, *ivhash_name;
 608     Error *local_err = NULL;
 609
 610     /*
 611      * The cipher_mode header contains a string that we have
 612      * to further parse, of the format
 613      *
 614      *    <cipher-mode>-<iv-generator>[:<iv-hash>]
 615      *
 616      * eg  cbc-essiv:sha256, cbc-plain64
 617      */
 618     ivgen_name = strchr(cipher_mode, '-');
 619     if (!ivgen_name) {
 620         error_setg(errp, "Unexpected cipher mode string format %s",
 621                    luks->header.cipher_mode);
 622         return -1;
 623     }
 624     *ivgen_name = '\0';
 625     ivgen_name++;
 626
 627     ivhash_name = strchr(ivgen_name, ':');
 628     if (!ivhash_name) {
 629         luks->ivgen_hash_alg = 0;
 630     } else {
 631         *ivhash_name = '\0';
 632         ivhash_name++;
 633
 634         luks->ivgen_hash_alg = qcrypto_block_luks_hash_name_lookup(ivhash_name,
 635                                                                    &local_err);
 636         if (local_err) {
 637             error_propagate(errp, local_err);
 638             return -1;
 639         }
 640     }
 641
 642     luks->cipher_mode = qcrypto_block_luks_cipher_mode_lookup(cipher_mode,
 643                                                               &local_err);
 644     if (local_err) {
 645         error_propagate(errp, local_err);
 646         return -1;
 647     }
 648
 649     luks->cipher_alg =
 650             qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
 651                                                   luks->cipher_mode,
 652                                                   luks->header.master_key_len,
 653                                                   &local_err);
 654     if (local_err) {
 655         error_propagate(errp, local_err);
 656         return -1;
 657     }
 658
 659     luks->hash_alg =
 660             qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
 661                                                 &local_err);
 662     if (local_err) {
 663         error_propagate(errp, local_err);
 664         return -1;
 665     }
 666
 667     luks->ivgen_alg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
 668                                                            &local_err);
 669     if (local_err) {
 670         error_propagate(errp, local_err);
 671         return -1;
 672     }
 673
 674     if (luks->ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
 675         if (!ivhash_name) {
 676             error_setg(errp, "Missing IV generator hash specification");
 677             return -1;
 678         }
 679         luks->ivgen_cipher_alg =
 680                 qcrypto_block_luks_essiv_cipher(luks->cipher_alg,
 681                                                 luks->ivgen_hash_alg,
 682                                                 &local_err);
 683         if (local_err) {
 684             error_propagate(errp, local_err);
 685             return -1;
 686         }
 687     } else {
 688
 689         /*
 690          * Note we parsed the ivhash_name earlier in the cipher_mode
 691          * spec string even with plain/plain64 ivgens, but we
 692          * will ignore it, since it is irrelevant for these ivgens.
 693          * This is for compat with dm-crypt which will silently
 694          * ignore hash names with these ivgens rather than report
 695          * an error about the invalid usage
 696          */
 697         luks->ivgen_cipher_alg = luks->cipher_alg;
 698     }
 699     return 0;
 700 }
 701
 702 /*
 703  * Given a key slot,  user password, and the master key,
 704  * will store the encrypted master key there, and update the
 705  * in-memory header. User must then write the in-memory header
 706  *
 707  * Returns:
 708  *    0 if the keyslot was written successfully
 709  *      with the provided password
 710  *   -1 if a fatal error occurred while storing the key
 711  */
 712 static int
 713 qcrypto_block_luks_store_key(QCryptoBlock *block,
 714                              unsigned int slot_idx,
 715                              const char *password,
 716                              uint8_t *masterkey,
 717                              uint64_t iter_time,
 718                              QCryptoBlockWriteFunc writefunc,
 719                              void *opaque,
 720                              Error **errp)
 721 {
 722     QCryptoBlockLUKS *luks = block->opaque;
 723     QCryptoBlockLUKSKeySlot *slot = &luks->header.key_slots[slot_idx];
 724     g_autofree uint8_t *splitkey = NULL;
 725     size_t splitkeylen;
 726     g_autofree uint8_t *slotkey = NULL;
 727     g_autoptr(QCryptoCipher) cipher = NULL;
 728     g_autoptr(QCryptoIVGen) ivgen = NULL;
 729     Error *local_err = NULL;
 730     uint64_t iters;
 731     int ret = -1;
 732
 733     if (qcrypto_random_bytes(slot->salt,
 734                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
 735                              errp) < 0) {
 736         goto cleanup;
 737     }
 738
 739     splitkeylen = luks->header.master_key_len * slot->stripes;
 740
 741     /*
 742      * Determine how many iterations are required to
 743      * hash the user password while consuming 1 second of compute
 744      * time
 745      */
 746     iters = qcrypto_pbkdf2_count_iters(luks->hash_alg,
 747                                        (uint8_t *)password, strlen(password),
 748                                        slot->salt,
 749                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
 750                                        luks->header.master_key_len,
 751                                        &local_err);
 752     if (local_err) {
 753         error_propagate(errp, local_err);
 754         goto cleanup;
 755     }
 756
 757     if (iters > (ULLONG_MAX / iter_time)) {
 758         error_setg_errno(errp, ERANGE,
 759                          "PBKDF iterations %llu too large to scale",
 760                          (unsigned long long)iters);
 761         goto cleanup;
 762     }
 763
 764     /* iter_time was in millis, but count_iters reported for secs */
 765     iters = iters * iter_time / 1000;
 766
 767     if (iters > UINT32_MAX) {
 768         error_setg_errno(errp, ERANGE,
 769                          "PBKDF iterations %llu larger than %u",
 770                          (unsigned long long)iters, UINT32_MAX);
 771         goto cleanup;
 772     }
 773
 774     slot->iterations =
 775         MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);
 776
 777
 778     /*
 779      * Generate a key that we'll use to encrypt the master
 780      * key, from the user's password
 781      */
 782     slotkey = g_new0(uint8_t, luks->header.master_key_len);
 783     if (qcrypto_pbkdf2(luks->hash_alg,
 784                        (uint8_t *)password, strlen(password),
 785                        slot->salt,
 786                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
 787                        slot->iterations,
 788                        slotkey, luks->header.master_key_len,
 789                        errp) < 0) {
 790         goto cleanup;
 791     }
 792
 793
 794     /*
 795      * Setup the encryption objects needed to encrypt the
 796      * master key material
 797      */
 798     cipher = qcrypto_cipher_new(luks->cipher_alg,
 799                                 luks->cipher_mode,
 800                                 slotkey, luks->header.master_key_len,
 801                                 errp);
 802     if (!cipher) {
 803         goto cleanup;
 804     }
 805
 806     ivgen = qcrypto_ivgen_new(luks->ivgen_alg,
 807                               luks->ivgen_cipher_alg,
 808                               luks->ivgen_hash_alg,
 809                               slotkey, luks->header.master_key_len,
 810                               errp);
 811     if (!ivgen) {
 812         goto cleanup;
 813     }
 814
 815     /*
 816      * Before storing the master key, we need to vastly
 817      * increase its size, as protection against forensic
 818      * disk data recovery
 819      */
 820     splitkey = g_new0(uint8_t, splitkeylen);
 821
 822     if (qcrypto_afsplit_encode(luks->hash_alg,
 823                                luks->header.master_key_len,
 824                                slot->stripes,
 825                                masterkey,
 826                                splitkey,
 827                                errp) < 0) {
 828         goto cleanup;
 829     }
 830
 831     /*
 832      * Now we encrypt the split master key with the key generated
 833      * from the user's password, before storing it
 834      */
 835     if (qcrypto_block_cipher_encrypt_helper(cipher, block->niv, ivgen,
 836                                             QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 837                                             0,
 838                                             splitkey,
 839                                             splitkeylen,
 840                                             errp) < 0) {
 841         goto cleanup;
 842     }
 843
 844     /* Write out the slot's master key material. */
 845     if (writefunc(block,
 846                   slot->key_offset_sector *
 847                   QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 848                   splitkey, splitkeylen,
 849                   opaque,
 850                   errp) != splitkeylen) {
 851         goto cleanup;
 852     }
 853
 854     slot->active = QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
 855
 856     if (qcrypto_block_luks_store_header(block,  writefunc, opaque, errp) < 0) {
 857         goto cleanup;
 858     }
 859
 860     ret = 0;
 861
 862 cleanup:
 863     if (slotkey) {
 864         memset(slotkey, 0, luks->header.master_key_len);
 865     }
 866     if (splitkey) {
 867         memset(splitkey, 0, splitkeylen);
 868     }
 869     return ret;
 870 }
 871
 872 /*
 873  * Given a key slot, and user password, this will attempt to unlock
 874  * the master encryption key from the key slot.
 875  *
 876  * Returns:
 877  *    0 if the key slot is disabled, or key could not be decrypted
 878  *      with the provided password
 879  *    1 if the key slot is enabled, and key decrypted successfully
 880  *      with the provided password
 881  *   -1 if a fatal error occurred loading the key
 882  */
 883 static int
 884 qcrypto_block_luks_load_key(QCryptoBlock *block,
 885                             size_t slot_idx,
 886                             const char *password,
 887                             uint8_t *masterkey,
 888                             QCryptoBlockReadFunc readfunc,
 889                             void *opaque,
 890                             Error **errp)
 891 {
 892     QCryptoBlockLUKS *luks = block->opaque;
 893     const QCryptoBlockLUKSKeySlot *slot = &luks->header.key_slots[slot_idx];
 894     g_autofree uint8_t *splitkey = NULL;
 895     size_t splitkeylen;
 896     g_autofree uint8_t *possiblekey = NULL;
 897     ssize_t rv;
 898     g_autoptr(QCryptoCipher) cipher = NULL;
 899     uint8_t keydigest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
 900     g_autoptr(QCryptoIVGen) ivgen = NULL;
 901     size_t niv;
 902
 903     if (slot->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
 904         return 0;
 905     }
 906
 907     splitkeylen = luks->header.master_key_len * slot->stripes;
 908     splitkey = g_new0(uint8_t, splitkeylen);
 909     possiblekey = g_new0(uint8_t, luks->header.master_key_len);
 910
 911     /*
 912      * The user password is used to generate a (possible)
 913      * decryption key. This may or may not successfully
 914      * decrypt the master key - we just blindly assume
 915      * the key is correct and validate the results of
 916      * decryption later.
 917      */
 918     if (qcrypto_pbkdf2(luks->hash_alg,
 919                        (const uint8_t *)password, strlen(password),
 920                        slot->salt, QCRYPTO_BLOCK_LUKS_SALT_LEN,
 921                        slot->iterations,
 922                        possiblekey, luks->header.master_key_len,
 923                        errp) < 0) {
 924         return -1;
 925     }
 926
 927     /*
 928      * We need to read the master key material from the
 929      * LUKS key material header. What we're reading is
 930      * not the raw master key, but rather the data after
 931      * it has been passed through AFSplit and the result
 932      * then encrypted.
 933      */
 934     rv = readfunc(block,
 935                   slot->key_offset_sector * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 936                   splitkey, splitkeylen,
 937                   opaque,
 938                   errp);
 939     if (rv < 0) {
 940         return -1;
 941     }
 942
 943
 944     /* Setup the cipher/ivgen that we'll use to try to decrypt
 945      * the split master key material */
 946     cipher = qcrypto_cipher_new(luks->cipher_alg,
 947                                 luks->cipher_mode,
 948                                 possiblekey,
 949                                 luks->header.master_key_len,
 950                                 errp);
 951     if (!cipher) {
 952         return -1;
 953     }
 954
 955     niv = qcrypto_cipher_get_iv_len(luks->cipher_alg,
 956                                     luks->cipher_mode);
 957
 958     ivgen = qcrypto_ivgen_new(luks->ivgen_alg,
 959                               luks->ivgen_cipher_alg,
 960                               luks->ivgen_hash_alg,
 961                               possiblekey,
 962                               luks->header.master_key_len,
 963                               errp);
 964     if (!ivgen) {
 965         return -1;
 966     }
 967
 968
 969     /*
 970      * The master key needs to be decrypted in the same
 971      * way that the block device payload will be decrypted
 972      * later. In particular we'll be using the IV generator
 973      * to reset the encryption cipher every time the master
 974      * key crosses a sector boundary.
 975      */
 976     if (qcrypto_block_cipher_decrypt_helper(cipher,
 977                                             niv,
 978                                             ivgen,
 979                                             QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
 980                                             0,
 981                                             splitkey,
 982                                             splitkeylen,
 983                                             errp) < 0) {
 984         return -1;
 985     }
 986
 987     /*
 988      * Now we've decrypted the split master key, join
 989      * it back together to get the actual master key.
 990      */
 991     if (qcrypto_afsplit_decode(luks->hash_alg,
 992                                luks->header.master_key_len,
 993                                slot->stripes,
 994                                splitkey,
 995                                masterkey,
 996                                errp) < 0) {
 997         return -1;
 998     }
 999
1000
1001     /*
1002      * We still don't know that the masterkey we got is valid,
1003      * because we just blindly assumed the user's password
1004      * was correct. This is where we now verify it. We are
1005      * creating a hash of the master key using PBKDF and
1006      * then comparing that to the hash stored in the key slot
1007      * header
1008      */
1009     if (qcrypto_pbkdf2(luks->hash_alg,
1010                        masterkey,
1011                        luks->header.master_key_len,
1012                        luks->header.master_key_salt,
1013                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1014                        luks->header.master_key_iterations,
1015                        keydigest,
1016                        G_N_ELEMENTS(keydigest),
1017                        errp) < 0) {
1018         return -1;
1019     }
1020
1021     if (memcmp(keydigest, luks->header.master_key_digest,
1022                QCRYPTO_BLOCK_LUKS_DIGEST_LEN) == 0) {
1023         /* Success, we got the right master key */
1024         return 1;
1025     }
1026
1027     /* Fail, user's password was not valid for this key slot,
1028      * tell caller to try another slot */
1029     return 0;
1030 }
1031
1032
1033 /*
1034  * Given a user password, this will iterate over all key
1035  * slots and try to unlock each active key slot using the
1036  * password until it successfully obtains a master key.
1037  *
1038  * Returns 0 if a key was loaded, -1 if no keys could be loaded
1039  */
1040 static int
1041 qcrypto_block_luks_find_key(QCryptoBlock *block,
1042                             const char *password,
1043                             uint8_t *masterkey,
1044                             QCryptoBlockReadFunc readfunc,
1045                             void *opaque,
1046                             Error **errp)
1047 {
1048     size_t i;
1049     int rv;
1050
1051     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1052         rv = qcrypto_block_luks_load_key(block,
1053                                          i,
1054                                          password,
1055                                          masterkey,
1056                                          readfunc,
1057                                          opaque,
1058                                          errp);
1059         if (rv < 0) {
1060             goto error;
1061         }
1062         if (rv == 1) {
1063             return 0;
1064         }
1065     }
1066
1067     error_setg(errp, "Invalid password, cannot unlock any keyslot");
1068  error:
1069     return -1;
1070 }
1071
1072
1073 static int
1074 qcrypto_block_luks_open(QCryptoBlock *block,
1075                         QCryptoBlockOpenOptions *options,
1076                         const char *optprefix,
1077                         QCryptoBlockReadFunc readfunc,
1078                         void *opaque,
1079                         unsigned int flags,
1080                         size_t n_threads,
1081                         Error **errp)
1082 {
1083     QCryptoBlockLUKS *luks = NULL;
1084     g_autofree uint8_t *masterkey = NULL;
1085     g_autofree char *password = NULL;
1086
1087     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
1088         if (!options->u.luks.key_secret) {
1089             error_setg(errp, "Parameter '%skey-secret' is required for cipher",
1090                        optprefix ? optprefix : "");
1091             return -1;
1092         }
1093         password = qcrypto_secret_lookup_as_utf8(
1094             options->u.luks.key_secret, errp);
1095         if (!password) {
1096             return -1;
1097         }
1098     }
1099
1100     luks = g_new0(QCryptoBlockLUKS, 1);
1101     block->opaque = luks;
1102
1103     if (qcrypto_block_luks_load_header(block, readfunc, opaque, errp) < 0) {
1104         goto fail;
1105     }
1106
1107     if (qcrypto_block_luks_check_header(luks, errp) < 0) {
1108         goto fail;
1109     }
1110
1111     if (qcrypto_block_luks_parse_header(luks, errp) < 0) {
1112         goto fail;
1113     }
1114
1115     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
1116         /* Try to find which key slot our password is valid for
1117          * and unlock the master key from that slot.
1118          */
1119
1120         masterkey = g_new0(uint8_t, luks->header.master_key_len);
1121
1122         if (qcrypto_block_luks_find_key(block,
1123                                         password,
1124                                         masterkey,
1125                                         readfunc, opaque,
1126                                         errp) < 0) {
1127             goto fail;
1128         }
1129
1130         /* We have a valid master key now, so can setup the
1131          * block device payload decryption objects
1132          */
1133         block->kdfhash = luks->hash_alg;
1134         block->niv = qcrypto_cipher_get_iv_len(luks->cipher_alg,
1135                                                luks->cipher_mode);
1136
1137         block->ivgen = qcrypto_ivgen_new(luks->ivgen_alg,
1138                                          luks->ivgen_cipher_alg,
1139                                          luks->ivgen_hash_alg,
1140                                          masterkey,
1141                                          luks->header.master_key_len,
1142                                          errp);
1143         if (!block->ivgen) {
1144             goto fail;
1145         }
1146
1147         if (qcrypto_block_init_cipher(block,
1148                                       luks->cipher_alg,
1149                                       luks->cipher_mode,
1150                                       masterkey,
1151                                       luks->header.master_key_len,
1152                                       n_threads,
1153                                       errp) < 0) {
1154             goto fail;
1155         }
1156     }
1157
1158     block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1159     block->payload_offset = luks->header.payload_offset_sector *
1160         block->sector_size;
1161
1162     return 0;
1163
1164  fail:
1165     qcrypto_block_free_cipher(block);
1166     qcrypto_ivgen_free(block->ivgen);
1167     g_free(luks);
1168     return -1;
1169 }
1170
1171
1172 static void
1173 qcrypto_block_luks_uuid_gen(uint8_t *uuidstr)
1174 {
1175     QemuUUID uuid;
1176     qemu_uuid_generate(&uuid);
1177     qemu_uuid_unparse(&uuid, (char *)uuidstr);
1178 }
1179
1180 static int
1181 qcrypto_block_luks_create(QCryptoBlock *block,
1182                           QCryptoBlockCreateOptions *options,
1183                           const char *optprefix,
1184                           QCryptoBlockInitFunc initfunc,
1185                           QCryptoBlockWriteFunc writefunc,
1186                           void *opaque,
1187                           Error **errp)
1188 {
1189     QCryptoBlockLUKS *luks;
1190     QCryptoBlockCreateOptionsLUKS luks_opts;
1191     Error *local_err = NULL;
1192     g_autofree uint8_t *masterkey = NULL;
1193     size_t header_sectors;
1194     size_t split_key_sectors;
1195     size_t i;
1196     g_autofree char *password = NULL;
1197     const char *cipher_alg;
1198     const char *cipher_mode;
1199     const char *ivgen_alg;
1200     const char *ivgen_hash_alg = NULL;
1201     const char *hash_alg;
1202     g_autofree char *cipher_mode_spec = NULL;
1203     uint64_t iters;
1204
1205     memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
1206     if (!luks_opts.has_iter_time) {
1207         luks_opts.iter_time = 2000;
1208     }
1209     if (!luks_opts.has_cipher_alg) {
1210         luks_opts.cipher_alg = QCRYPTO_CIPHER_ALG_AES_256;
1211     }
1212     if (!luks_opts.has_cipher_mode) {
1213         luks_opts.cipher_mode = QCRYPTO_CIPHER_MODE_XTS;
1214     }
1215     if (!luks_opts.has_ivgen_alg) {
1216         luks_opts.ivgen_alg = QCRYPTO_IVGEN_ALG_PLAIN64;
1217     }
1218     if (!luks_opts.has_hash_alg) {
1219         luks_opts.hash_alg = QCRYPTO_HASH_ALG_SHA256;
1220     }
1221     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1222         if (!luks_opts.has_ivgen_hash_alg) {
1223             luks_opts.ivgen_hash_alg = QCRYPTO_HASH_ALG_SHA256;
1224             luks_opts.has_ivgen_hash_alg = true;
1225         }
1226     }
1227
1228     luks = g_new0(QCryptoBlockLUKS, 1);
1229     block->opaque = luks;
1230
1231     luks->cipher_alg = luks_opts.cipher_alg;
1232     luks->cipher_mode = luks_opts.cipher_mode;
1233     luks->ivgen_alg = luks_opts.ivgen_alg;
1234     luks->ivgen_hash_alg = luks_opts.ivgen_hash_alg;
1235     luks->hash_alg = luks_opts.hash_alg;
1236
1237
1238     /* Note we're allowing ivgen_hash_alg to be set even for
1239      * non-essiv iv generators that don't need a hash. It will
1240      * be silently ignored, for compatibility with dm-crypt */
1241
1242     if (!options->u.luks.key_secret) {
1243         error_setg(errp, "Parameter '%skey-secret' is required for cipher",
1244                    optprefix ? optprefix : "");
1245         goto error;
1246     }
1247     password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret, errp);
1248     if (!password) {
1249         goto error;
1250     }
1251
1252
1253     memcpy(luks->header.magic, qcrypto_block_luks_magic,
1254            QCRYPTO_BLOCK_LUKS_MAGIC_LEN);
1255
1256     /* We populate the header in native endianness initially and
1257      * then convert everything to big endian just before writing
1258      * it out to disk
1259      */
1260     luks->header.version = QCRYPTO_BLOCK_LUKS_VERSION;
1261     qcrypto_block_luks_uuid_gen(luks->header.uuid);
1262
1263     cipher_alg = qcrypto_block_luks_cipher_alg_lookup(luks_opts.cipher_alg,
1264                                                       errp);
1265     if (!cipher_alg) {
1266         goto error;
1267     }
1268
1269     cipher_mode = QCryptoCipherMode_str(luks_opts.cipher_mode);
1270     ivgen_alg = QCryptoIVGenAlgorithm_str(luks_opts.ivgen_alg);
1271     if (luks_opts.has_ivgen_hash_alg) {
1272         ivgen_hash_alg = QCryptoHashAlgorithm_str(luks_opts.ivgen_hash_alg);
1273         cipher_mode_spec = g_strdup_printf("%s-%s:%s", cipher_mode, ivgen_alg,
1274                                            ivgen_hash_alg);
1275     } else {
1276         cipher_mode_spec = g_strdup_printf("%s-%s", cipher_mode, ivgen_alg);
1277     }
1278     hash_alg = QCryptoHashAlgorithm_str(luks_opts.hash_alg);
1279
1280
1281     if (strlen(cipher_alg) >= QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN) {
1282         error_setg(errp, "Cipher name '%s' is too long for LUKS header",
1283                    cipher_alg);
1284         goto error;
1285     }
1286     if (strlen(cipher_mode_spec) >= QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN) {
1287         error_setg(errp, "Cipher mode '%s' is too long for LUKS header",
1288                    cipher_mode_spec);
1289         goto error;
1290     }
1291     if (strlen(hash_alg) >= QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN) {
1292         error_setg(errp, "Hash name '%s' is too long for LUKS header",
1293                    hash_alg);
1294         goto error;
1295     }
1296
1297     if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1298         luks->ivgen_cipher_alg =
1299                 qcrypto_block_luks_essiv_cipher(luks_opts.cipher_alg,
1300                                                 luks_opts.ivgen_hash_alg,
1301                                                 &local_err);
1302         if (local_err) {
1303             error_propagate(errp, local_err);
1304             goto error;
1305         }
1306     } else {
1307         luks->ivgen_cipher_alg = luks_opts.cipher_alg;
1308     }
1309
1310     strcpy(luks->header.cipher_name, cipher_alg);
1311     strcpy(luks->header.cipher_mode, cipher_mode_spec);
1312     strcpy(luks->header.hash_spec, hash_alg);
1313
1314     luks->header.master_key_len =
1315         qcrypto_cipher_get_key_len(luks_opts.cipher_alg);
1316
1317     if (luks_opts.cipher_mode == QCRYPTO_CIPHER_MODE_XTS) {
1318         luks->header.master_key_len *= 2;
1319     }
1320
1321     /* Generate the salt used for hashing the master key
1322      * with PBKDF later
1323      */
1324     if (qcrypto_random_bytes(luks->header.master_key_salt,
1325                              QCRYPTO_BLOCK_LUKS_SALT_LEN,
1326                              errp) < 0) {
1327         goto error;
1328     }
1329
1330     /* Generate random master key */
1331     masterkey = g_new0(uint8_t, luks->header.master_key_len);
1332     if (qcrypto_random_bytes(masterkey,
1333                              luks->header.master_key_len, errp) < 0) {
1334         goto error;
1335     }
1336
1337
1338     /* Setup the block device payload encryption objects */
1339     if (qcrypto_block_init_cipher(block, luks_opts.cipher_alg,
1340                                   luks_opts.cipher_mode, masterkey,
1341                                   luks->header.master_key_len, 1, errp) < 0) {
1342         goto error;
1343     }
1344
1345     block->kdfhash = luks_opts.hash_alg;
1346     block->niv = qcrypto_cipher_get_iv_len(luks_opts.cipher_alg,
1347                                            luks_opts.cipher_mode);
1348     block->ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
1349                                      luks->ivgen_cipher_alg,
1350                                      luks_opts.ivgen_hash_alg,
1351                                      masterkey, luks->header.master_key_len,
1352                                      errp);
1353
1354     if (!block->ivgen) {
1355         goto error;
1356     }
1357
1358
1359     /* Determine how many iterations we need to hash the master
1360      * key, in order to have 1 second of compute time used
1361      */
1362     iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
1363                                        masterkey, luks->header.master_key_len,
1364                                        luks->header.master_key_salt,
1365                                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1366                                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1367                                        &local_err);
1368     if (local_err) {
1369         error_propagate(errp, local_err);
1370         goto error;
1371     }
1372
1373     if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
1374         error_setg_errno(errp, ERANGE,
1375                          "PBKDF iterations %llu too large to scale",
1376                          (unsigned long long)iters);
1377         goto error;
1378     }
1379
1380     /* iter_time was in millis, but count_iters reported for secs */
1381     iters = iters * luks_opts.iter_time / 1000;
1382
1383     /* Why /= 8 ?  That matches cryptsetup, but there's no
1384      * explanation why they chose /= 8... Probably so that
1385      * if all 8 keyslots are active we only spend 1 second
1386      * in total time to check all keys */
1387     iters /= 8;
1388     if (iters > UINT32_MAX) {
1389         error_setg_errno(errp, ERANGE,
1390                          "PBKDF iterations %llu larger than %u",
1391                          (unsigned long long)iters, UINT32_MAX);
1392         goto error;
1393     }
1394     iters = MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS);
1395     luks->header.master_key_iterations = iters;
1396
1397     /* Hash the master key, saving the result in the LUKS
1398      * header. This hash is used when opening the encrypted
1399      * device to verify that the user password unlocked a
1400      * valid master key
1401      */
1402     if (qcrypto_pbkdf2(luks_opts.hash_alg,
1403                        masterkey, luks->header.master_key_len,
1404                        luks->header.master_key_salt,
1405                        QCRYPTO_BLOCK_LUKS_SALT_LEN,
1406                        luks->header.master_key_iterations,
1407                        luks->header.master_key_digest,
1408                        QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
1409                        errp) < 0) {
1410         goto error;
1411     }
1412
1413     /* start with the sector that follows the header*/
1414     header_sectors = QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
1415         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1416
1417     split_key_sectors =
1418         qcrypto_block_luks_splitkeylen_sectors(luks,
1419                                                header_sectors,
1420                                                QCRYPTO_BLOCK_LUKS_STRIPES);
1421
1422     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1423         QCryptoBlockLUKSKeySlot *slot = &luks->header.key_slots[i];
1424         slot->active = QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
1425
1426         slot->key_offset_sector = header_sectors + i * split_key_sectors;
1427         slot->stripes = QCRYPTO_BLOCK_LUKS_STRIPES;
1428     }
1429
1430     /* The total size of the LUKS headers is the partition header + key
1431      * slot headers, rounded up to the nearest sector, combined with
1432      * the size of each master key material region, also rounded up
1433      * to the nearest sector */
1434     luks->header.payload_offset_sector = header_sectors +
1435             QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS * split_key_sectors;
1436
1437     block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1438     block->payload_offset = luks->header.payload_offset_sector *
1439         block->sector_size;
1440
1441     /* Reserve header space to match payload offset */
1442     initfunc(block, block->payload_offset, opaque, &local_err);
1443     if (local_err) {
1444         error_propagate(errp, local_err);
1445         goto error;
1446     }
1447
1448
1449     /* populate the slot 0 with the password encrypted master key*/
1450     /* This will also store the header */
1451     if (qcrypto_block_luks_store_key(block,
1452                                      0,
1453                                      password,
1454                                      masterkey,
1455                                      luks_opts.iter_time,
1456                                      writefunc,
1457                                      opaque,
1458                                      errp) < 0) {
1459         goto error;
1460     }
1461
1462     memset(masterkey, 0, luks->header.master_key_len);
1463
1464     return 0;
1465
1466  error:
1467     if (masterkey) {
1468         memset(masterkey, 0, luks->header.master_key_len);
1469     }
1470
1471     qcrypto_block_free_cipher(block);
1472     qcrypto_ivgen_free(block->ivgen);
1473
1474     g_free(luks);
1475     return -1;
1476 }
1477
1478
1479 static int qcrypto_block_luks_get_info(QCryptoBlock *block,
1480                                        QCryptoBlockInfo *info,
1481                                        Error **errp)
1482 {
1483     QCryptoBlockLUKS *luks = block->opaque;
1484     QCryptoBlockInfoLUKSSlot *slot;
1485     QCryptoBlockInfoLUKSSlotList *slots = NULL, **prev = &info->u.luks.slots;
1486     size_t i;
1487
1488     info->u.luks.cipher_alg = luks->cipher_alg;
1489     info->u.luks.cipher_mode = luks->cipher_mode;
1490     info->u.luks.ivgen_alg = luks->ivgen_alg;
1491     if (info->u.luks.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
1492         info->u.luks.has_ivgen_hash_alg = true;
1493         info->u.luks.ivgen_hash_alg = luks->ivgen_hash_alg;
1494     }
1495     info->u.luks.hash_alg = luks->hash_alg;
1496     info->u.luks.payload_offset = block->payload_offset;
1497     info->u.luks.master_key_iters = luks->header.master_key_iterations;
1498     info->u.luks.uuid = g_strndup((const char *)luks->header.uuid,
1499                                   sizeof(luks->header.uuid));
1500
1501     for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
1502         slots = g_new0(QCryptoBlockInfoLUKSSlotList, 1);
1503         *prev = slots;
1504
1505         slots->value = slot = g_new0(QCryptoBlockInfoLUKSSlot, 1);
1506         slot->active = luks->header.key_slots[i].active ==
1507             QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
1508         slot->key_offset = luks->header.key_slots[i].key_offset_sector
1509              * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
1510         if (slot->active) {
1511             slot->has_iters = true;
1512             slot->iters = luks->header.key_slots[i].iterations;
1513             slot->has_stripes = true;
1514             slot->stripes = luks->header.key_slots[i].stripes;
1515         }
1516
1517         prev = &slots->next;
1518     }
1519
1520     return 0;
1521 }
1522
1523
1524 static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
1525 {
1526     g_free(block->opaque);
1527 }
1528
1529
1530 static int
1531 qcrypto_block_luks_decrypt(QCryptoBlock *block,
1532                            uint64_t offset,
1533                            uint8_t *buf,
1534                            size_t len,
1535                            Error **errp)
1536 {
1537     assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1538     assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1539     return qcrypto_block_decrypt_helper(block,
1540                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1541                                         offset, buf, len, errp);
1542 }
1543
1544
1545 static int
1546 qcrypto_block_luks_encrypt(QCryptoBlock *block,
1547                            uint64_t offset,
1548                            uint8_t *buf,
1549                            size_t len,
1550                            Error **errp)
1551 {
1552     assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1553     assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
1554     return qcrypto_block_encrypt_helper(block,
1555                                         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
1556                                         offset, buf, len, errp);
1557 }
1558
1559
1560 const QCryptoBlockDriver qcrypto_block_driver_luks = {
1561     .open = qcrypto_block_luks_open,
1562     .create = qcrypto_block_luks_create,
1563     .get_info = qcrypto_block_luks_get_info,
1564     .cleanup = qcrypto_block_luks_cleanup,
1565     .decrypt = qcrypto_block_luks_decrypt,
1566     .encrypt = qcrypto_block_luks_encrypt,
1567     .has_format = qcrypto_block_luks_has_format,
1568 };