aboutsummaryrefslogtreecommitdiff
path: root/crypto/block-luks.c
blob: 57381247733729a50b840ce003748325be4be4b0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
/*
 * QEMU Crypto block device encryption LUKS format
 *
 * Copyright (c) 2015-2016 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/bswap.h"

#include "block-luks.h"

#include "crypto/hash.h"
#include "crypto/afsplit.h"
#include "crypto/pbkdf.h"
#include "crypto/secret.h"
#include "crypto/random.h"
#include "qemu/uuid.h"

#include "qemu/coroutine.h"

/*
 * Reference for the LUKS format implemented here is
 *
 *   docs/on-disk-format.pdf
 *
 * in 'cryptsetup' package source code
 *
 * This file implements the 1.2.1 specification, dated
 * Oct 16, 2011.
 */

typedef struct QCryptoBlockLUKS QCryptoBlockLUKS;
typedef struct QCryptoBlockLUKSHeader QCryptoBlockLUKSHeader;
typedef struct QCryptoBlockLUKSKeySlot QCryptoBlockLUKSKeySlot;


/* The following constants are all defined by the LUKS spec */
#define QCRYPTO_BLOCK_LUKS_VERSION 1

#define QCRYPTO_BLOCK_LUKS_MAGIC_LEN 6
#define QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN 32
#define QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN 32
#define QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN 32
#define QCRYPTO_BLOCK_LUKS_DIGEST_LEN 20
#define QCRYPTO_BLOCK_LUKS_SALT_LEN 32
#define QCRYPTO_BLOCK_LUKS_UUID_LEN 40
#define QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS 8
#define QCRYPTO_BLOCK_LUKS_STRIPES 4000
#define QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS 1000
#define QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS 1000
#define QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET 4096

#define QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED 0x0000DEAD
#define QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED 0x00AC71F3

#define QCRYPTO_BLOCK_LUKS_SECTOR_SIZE 512LL

static const char qcrypto_block_luks_magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN] = {
    'L', 'U', 'K', 'S', 0xBA, 0xBE
};

typedef struct QCryptoBlockLUKSNameMap QCryptoBlockLUKSNameMap;
struct QCryptoBlockLUKSNameMap {
    const char *name;
    int id;
};

typedef struct QCryptoBlockLUKSCipherSizeMap QCryptoBlockLUKSCipherSizeMap;
struct QCryptoBlockLUKSCipherSizeMap {
    uint32_t key_bytes;
    int id;
};
typedef struct QCryptoBlockLUKSCipherNameMap QCryptoBlockLUKSCipherNameMap;
struct QCryptoBlockLUKSCipherNameMap {
    const char *name;
    const QCryptoBlockLUKSCipherSizeMap *sizes;
};


static const QCryptoBlockLUKSCipherSizeMap
qcrypto_block_luks_cipher_size_map_aes[] = {
    { 16, QCRYPTO_CIPHER_ALG_AES_128 },
    { 24, QCRYPTO_CIPHER_ALG_AES_192 },
    { 32, QCRYPTO_CIPHER_ALG_AES_256 },
    { 0, 0 },
};

static const QCryptoBlockLUKSCipherSizeMap
qcrypto_block_luks_cipher_size_map_cast5[] = {
    { 16, QCRYPTO_CIPHER_ALG_CAST5_128 },
    { 0, 0 },
};

static const QCryptoBlockLUKSCipherSizeMap
qcrypto_block_luks_cipher_size_map_serpent[] = {
    { 16, QCRYPTO_CIPHER_ALG_SERPENT_128 },
    { 24, QCRYPTO_CIPHER_ALG_SERPENT_192 },
    { 32, QCRYPTO_CIPHER_ALG_SERPENT_256 },
    { 0, 0 },
};

static const QCryptoBlockLUKSCipherSizeMap
qcrypto_block_luks_cipher_size_map_twofish[] = {
    { 16, QCRYPTO_CIPHER_ALG_TWOFISH_128 },
    { 24, QCRYPTO_CIPHER_ALG_TWOFISH_192 },
    { 32, QCRYPTO_CIPHER_ALG_TWOFISH_256 },
    { 0, 0 },
};

static const QCryptoBlockLUKSCipherNameMap
qcrypto_block_luks_cipher_name_map[] = {
    { "aes", qcrypto_block_luks_cipher_size_map_aes },
    { "cast5", qcrypto_block_luks_cipher_size_map_cast5 },
    { "serpent", qcrypto_block_luks_cipher_size_map_serpent },
    { "twofish", qcrypto_block_luks_cipher_size_map_twofish },
};


/*
 * This struct is written to disk in big-endian format,
 * but operated upon in native-endian format.
 */
struct QCryptoBlockLUKSKeySlot {
    /* state of keyslot, enabled/disable */
    uint32_t active;
    /* iterations for PBKDF2 */
    uint32_t iterations;
    /* salt for PBKDF2 */
    uint8_t salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
    /* start sector of key material */
    uint32_t key_offset;
    /* number of anti-forensic stripes */
    uint32_t stripes;
} QEMU_PACKED;

QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSKeySlot) != 48);


/*
 * This struct is written to disk in big-endian format,
 * but operated upon in native-endian format.
 */
struct QCryptoBlockLUKSHeader {
    /* 'L', 'U', 'K', 'S', '0xBA', '0xBE' */
    char magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN];

    /* LUKS version, currently 1 */
    uint16_t version;

    /* cipher name specification (aes, etc) */
    char cipher_name[QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN];

    /* cipher mode specification (cbc-plain, xts-essiv:sha256, etc) */
    char cipher_mode[QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN];

    /* hash specification (sha256, etc) */
    char hash_spec[QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN];

    /* start offset of the volume data (in 512 byte sectors) */
    uint32_t payload_offset;

    /* Number of key bytes */
    uint32_t key_bytes;

    /* master key checksum after PBKDF2 */
    uint8_t master_key_digest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];

    /* salt for master key PBKDF2 */
    uint8_t master_key_salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];

    /* iterations for master key PBKDF2 */
    uint32_t master_key_iterations;

    /* UUID of the partition in standard ASCII representation */
    uint8_t uuid[QCRYPTO_BLOCK_LUKS_UUID_LEN];

    /* key slots */
    QCryptoBlockLUKSKeySlot key_slots[QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS];
} QEMU_PACKED;

QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSHeader) != 592);


struct QCryptoBlockLUKS {
    QCryptoBlockLUKSHeader header;

    /* Cache parsed versions of what's in header fields,
     * as we can't rely on QCryptoBlock.cipher being
     * non-NULL */
    QCryptoCipherAlgorithm cipher_alg;
    QCryptoCipherMode cipher_mode;
    QCryptoIVGenAlgorithm ivgen_alg;
    QCryptoHashAlgorithm ivgen_hash_alg;
    QCryptoHashAlgorithm hash_alg;
};


static int qcrypto_block_luks_cipher_name_lookup(const char *name,
                                                 QCryptoCipherMode mode,
                                                 uint32_t key_bytes,
                                                 Error **errp)
{
    const QCryptoBlockLUKSCipherNameMap *map =
        qcrypto_block_luks_cipher_name_map;
    size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
    size_t i, j;

    if (mode == QCRYPTO_CIPHER_MODE_XTS) {
        key_bytes /= 2;
    }

    for (i = 0; i < maplen; i++) {
        if (!g_str_equal(map[i].name, name)) {
            continue;
        }
        for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
            if (map[i].sizes[j].key_bytes == key_bytes) {
                return map[i].sizes[j].id;
            }
        }
    }

    error_setg(errp, "Algorithm %s with key size %d bytes not supported",
               name, key_bytes);
    return 0;
}

static const char *
qcrypto_block_luks_cipher_alg_lookup(QCryptoCipherAlgorithm alg,
                                     Error **errp)
{
    const QCryptoBlockLUKSCipherNameMap *map =
        qcrypto_block_luks_cipher_name_map;
    size_t maplen = G_N_ELEMENTS(qcrypto_block_luks_cipher_name_map);
    size_t i, j;
    for (i = 0; i < maplen; i++) {
        for (j = 0; j < map[i].sizes[j].key_bytes; j++) {
            if (map[i].sizes[j].id == alg) {
                return map[i].name;
            }
        }
    }

    error_setg(errp, "Algorithm '%s' not supported",
               QCryptoCipherAlgorithm_str(alg));
    return NULL;
}

/* XXX replace with qapi_enum_parse() in future, when we can
 * make that function emit a more friendly error message */
static int qcrypto_block_luks_name_lookup(const char *name,
                                          const QEnumLookup *map,
                                          const char *type,
                                          Error **errp)
{
    int ret = qapi_enum_parse(map, name, -1, NULL);

    if (ret < 0) {
        error_setg(errp, "%s %s not supported", type, name);
        return 0;
    }
    return ret;
}

#define qcrypto_block_luks_cipher_mode_lookup(name, errp)               \
    qcrypto_block_luks_name_lookup(name,                                \
                                   &QCryptoCipherMode_lookup,           \
                                   "Cipher mode",                       \
                                   errp)

#define qcrypto_block_luks_hash_name_lookup(name, errp)                 \
    qcrypto_block_luks_name_lookup(name,                                \
                                   &QCryptoHashAlgorithm_lookup,        \
                                   "Hash algorithm",                    \
                                   errp)

#define qcrypto_block_luks_ivgen_name_lookup(name, errp)                \
    qcrypto_block_luks_name_lookup(name,                                \
                                   &QCryptoIVGenAlgorithm_lookup,       \
                                   "IV generator",                      \
                                   errp)


static bool
qcrypto_block_luks_has_format(const uint8_t *buf,
                              size_t buf_size)
{
    const QCryptoBlockLUKSHeader *luks_header = (const void *)buf;

    if (buf_size >= offsetof(QCryptoBlockLUKSHeader, cipher_name) &&
        memcmp(luks_header->magic, qcrypto_block_luks_magic,
               QCRYPTO_BLOCK_LUKS_MAGIC_LEN) == 0 &&
        be16_to_cpu(luks_header->version) == QCRYPTO_BLOCK_LUKS_VERSION) {
        return true;
    } else {
        return false;
    }
}


/**
 * Deal with a quirk of dm-crypt usage of ESSIV.
 *
 * When calculating ESSIV IVs, the cipher length used by ESSIV
 * may be different from the cipher length used for the block
 * encryption, becauses dm-crypt uses the hash digest length
 * as the key size. ie, if you have AES 128 as the block cipher
 * and SHA 256 as ESSIV hash, then ESSIV will use AES 256 as
 * the cipher since that gets a key length matching the digest
 * size, not AES 128 with truncated digest as might be imagined
 */
static QCryptoCipherAlgorithm
qcrypto_block_luks_essiv_cipher(QCryptoCipherAlgorithm cipher,
                                QCryptoHashAlgorithm hash,
                                Error **errp)
{
    size_t digestlen = qcrypto_hash_digest_len(hash);
    size_t keylen = qcrypto_cipher_get_key_len(cipher);
    if (digestlen == keylen) {
        return cipher;
    }

    switch (cipher) {
    case QCRYPTO_CIPHER_ALG_AES_128:
    case QCRYPTO_CIPHER_ALG_AES_192:
    case QCRYPTO_CIPHER_ALG_AES_256:
        if (digestlen == qcrypto_cipher_get_key_len(
                QCRYPTO_CIPHER_ALG_AES_128)) {
            return QCRYPTO_CIPHER_ALG_AES_128;
        } else if (digestlen == qcrypto_cipher_get_key_len(
                       QCRYPTO_CIPHER_ALG_AES_192)) {
            return QCRYPTO_CIPHER_ALG_AES_192;
        } else if (digestlen == qcrypto_cipher_get_key_len(
                       QCRYPTO_CIPHER_ALG_AES_256)) {
            return QCRYPTO_CIPHER_ALG_AES_256;
        } else {
            error_setg(errp, "No AES cipher with key size %zu available",
                       digestlen);
            return 0;
        }
        break;
    case QCRYPTO_CIPHER_ALG_SERPENT_128:
    case QCRYPTO_CIPHER_ALG_SERPENT_192:
    case QCRYPTO_CIPHER_ALG_SERPENT_256:
        if (digestlen == qcrypto_cipher_get_key_len(
                QCRYPTO_CIPHER_ALG_SERPENT_128)) {
            return QCRYPTO_CIPHER_ALG_SERPENT_128;
        } else if (digestlen == qcrypto_cipher_get_key_len(
                       QCRYPTO_CIPHER_ALG_SERPENT_192)) {
            return QCRYPTO_CIPHER_ALG_SERPENT_192;
        } else if (digestlen == qcrypto_cipher_get_key_len(
                       QCRYPTO_CIPHER_ALG_SERPENT_256)) {
            return QCRYPTO_CIPHER_ALG_SERPENT_256;
        } else {
            error_setg(errp, "No Serpent cipher with key size %zu available",
                       digestlen);
            return 0;
        }
        break;
    case QCRYPTO_CIPHER_ALG_TWOFISH_128:
    case QCRYPTO_CIPHER_ALG_TWOFISH_192:
    case QCRYPTO_CIPHER_ALG_TWOFISH_256:
        if (digestlen == qcrypto_cipher_get_key_len(
                QCRYPTO_CIPHER_ALG_TWOFISH_128)) {
            return QCRYPTO_CIPHER_ALG_TWOFISH_128;
        } else if (digestlen == qcrypto_cipher_get_key_len(
                       QCRYPTO_CIPHER_ALG_TWOFISH_192)) {
            return QCRYPTO_CIPHER_ALG_TWOFISH_192;
        } else if (digestlen == qcrypto_cipher_get_key_len(
                       QCRYPTO_CIPHER_ALG_TWOFISH_256)) {
            return QCRYPTO_CIPHER_ALG_TWOFISH_256;
        } else {
            error_setg(errp, "No Twofish cipher with key size %zu available",
                       digestlen);
            return 0;
        }
        break;
    default:
        error_setg(errp, "Cipher %s not supported with essiv",
                   QCryptoCipherAlgorithm_str(cipher));
        return 0;
    }
}

/*
 * Given a key slot, and user password, this will attempt to unlock
 * the master encryption key from the key slot.
 *
 * Returns:
 *    0 if the key slot is disabled, or key could not be decrypted
 *      with the provided password
 *    1 if the key slot is enabled, and key decrypted successfully
 *      with the provided password
 *   -1 if a fatal error occurred loading the key
 */
static int
qcrypto_block_luks_load_key(QCryptoBlock *block,
                            QCryptoBlockLUKSKeySlot *slot,
                            const char *password,
                            QCryptoCipherAlgorithm cipheralg,
                            QCryptoCipherMode ciphermode,
                            QCryptoHashAlgorithm hash,
                            QCryptoIVGenAlgorithm ivalg,
                            QCryptoCipherAlgorithm ivcipheralg,
                            QCryptoHashAlgorithm ivhash,
                            uint8_t *masterkey,
                            size_t masterkeylen,
                            QCryptoBlockReadFunc readfunc,
                            void *opaque,
                            Error **errp)
{
    QCryptoBlockLUKS *luks = block->opaque;
    uint8_t *splitkey;
    size_t splitkeylen;
    uint8_t *possiblekey;
    int ret = -1;
    ssize_t rv;
    QCryptoCipher *cipher = NULL;
    uint8_t keydigest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
    QCryptoIVGen *ivgen = NULL;
    size_t niv;

    if (slot->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
        return 0;
    }

    splitkeylen = masterkeylen * slot->stripes;
    splitkey = g_new0(uint8_t, splitkeylen);
    possiblekey = g_new0(uint8_t, masterkeylen);

    /*
     * The user password is used to generate a (possible)
     * decryption key. This may or may not successfully
     * decrypt the master key - we just blindly assume
     * the key is correct and validate the results of
     * decryption later.
     */
    if (qcrypto_pbkdf2(hash,
                       (const uint8_t *)password, strlen(password),
                       slot->salt, QCRYPTO_BLOCK_LUKS_SALT_LEN,
                       slot->iterations,
                       possiblekey, masterkeylen,
                       errp) < 0) {
        goto cleanup;
    }

    /*
     * We need to read the master key material from the
     * LUKS key material header. What we're reading is
     * not the raw master key, but rather the data after
     * it has been passed through AFSplit and the result
     * then encrypted.
     */
    rv = readfunc(block,
                  slot->key_offset * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
                  splitkey, splitkeylen,
                  opaque,
                  errp);
    if (rv < 0) {
        goto cleanup;
    }


    /* Setup the cipher/ivgen that we'll use to try to decrypt
     * the split master key material */
    cipher = qcrypto_cipher_new(cipheralg, ciphermode,
                                possiblekey, masterkeylen,
                                errp);
    if (!cipher) {
        goto cleanup;
    }

    niv = qcrypto_cipher_get_iv_len(cipheralg,
                                    ciphermode);
    ivgen = qcrypto_ivgen_new(ivalg,
                              ivcipheralg,
                              ivhash,
                              possiblekey, masterkeylen,
                              errp);
    if (!ivgen) {
        goto cleanup;
    }


    /*
     * The master key needs to be decrypted in the same
     * way that the block device payload will be decrypted
     * later. In particular we'll be using the IV generator
     * to reset the encryption cipher every time the master
     * key crosses a sector boundary.
     */
    if (qcrypto_block_decrypt_helper(cipher,
                                     niv,
                                     ivgen,
                                     QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
                                     0,
                                     splitkey,
                                     splitkeylen,
                                     errp) < 0) {
        goto cleanup;
    }

    /*
     * Now we've decrypted the split master key, join
     * it back together to get the actual master key.
     */
    if (qcrypto_afsplit_decode(hash,
                               masterkeylen,
                               slot->stripes,
                               splitkey,
                               masterkey,
                               errp) < 0) {
        goto cleanup;
    }


    /*
     * We still don't know that the masterkey we got is valid,
     * because we just blindly assumed the user's password
     * was correct. This is where we now verify it. We are
     * creating a hash of the master key using PBKDF and
     * then comparing that to the hash stored in the key slot
     * header
     */
    if (qcrypto_pbkdf2(hash,
                       masterkey, masterkeylen,
                       luks->header.master_key_salt,
                       QCRYPTO_BLOCK_LUKS_SALT_LEN,
                       luks->header.master_key_iterations,
                       keydigest, G_N_ELEMENTS(keydigest),
                       errp) < 0) {
        goto cleanup;
    }

    if (memcmp(keydigest, luks->header.master_key_digest,
               QCRYPTO_BLOCK_LUKS_DIGEST_LEN) == 0) {
        /* Success, we got the right master key */
        ret = 1;
        goto cleanup;
    }

    /* Fail, user's password was not valid for this key slot,
     * tell caller to try another slot */
    ret = 0;

 cleanup:
    qcrypto_ivgen_free(ivgen);
    qcrypto_cipher_free(cipher);
    g_free(splitkey);
    g_free(possiblekey);
    return ret;
}


/*
 * Given a user password, this will iterate over all key
 * slots and try to unlock each active key slot using the
 * password until it successfully obtains a master key.
 *
 * Returns 0 if a key was loaded, -1 if no keys could be loaded
 */
static int
qcrypto_block_luks_find_key(QCryptoBlock *block,
                            const char *password,
                            QCryptoCipherAlgorithm cipheralg,
                            QCryptoCipherMode ciphermode,
                            QCryptoHashAlgorithm hash,
                            QCryptoIVGenAlgorithm ivalg,
                            QCryptoCipherAlgorithm ivcipheralg,
                            QCryptoHashAlgorithm ivhash,
                            uint8_t **masterkey,
                            size_t *masterkeylen,
                            QCryptoBlockReadFunc readfunc,
                            void *opaque,
                            Error **errp)
{
    QCryptoBlockLUKS *luks = block->opaque;
    size_t i;
    int rv;

    *masterkey = g_new0(uint8_t, luks->header.key_bytes);
    *masterkeylen = luks->header.key_bytes;

    for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
        rv = qcrypto_block_luks_load_key(block,
                                         &luks->header.key_slots[i],
                                         password,
                                         cipheralg,
                                         ciphermode,
                                         hash,
                                         ivalg,
                                         ivcipheralg,
                                         ivhash,
                                         *masterkey,
                                         *masterkeylen,
                                         readfunc,
                                         opaque,
                                         errp);
        if (rv < 0) {
            goto error;
        }
        if (rv == 1) {
            return 0;
        }
    }

    error_setg(errp, "Invalid password, cannot unlock any keyslot");

 error:
    g_free(*masterkey);
    *masterkey = NULL;
    *masterkeylen = 0;
    return -1;
}


static int
qcrypto_block_luks_open(QCryptoBlock *block,
                        QCryptoBlockOpenOptions *options,
                        const char *optprefix,
                        QCryptoBlockReadFunc readfunc,
                        void *opaque,
                        unsigned int flags,
                        Error **errp)
{
    QCryptoBlockLUKS *luks;
    Error *local_err = NULL;
    int ret = 0;
    size_t i;
    ssize_t rv;
    uint8_t *masterkey = NULL;
    size_t masterkeylen;
    char *ivgen_name, *ivhash_name;
    QCryptoCipherMode ciphermode;
    QCryptoCipherAlgorithm cipheralg;
    QCryptoIVGenAlgorithm ivalg;
    QCryptoCipherAlgorithm ivcipheralg;
    QCryptoHashAlgorithm hash;
    QCryptoHashAlgorithm ivhash;
    char *password = NULL;

    if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
        if (!options->u.luks.key_secret) {
            error_setg(errp, "Parameter '%skey-secret' is required for cipher",
                       optprefix ? optprefix : "");
            return -1;
        }
        password = qcrypto_secret_lookup_as_utf8(
            options->u.luks.key_secret, errp);
        if (!password) {
            return -1;
        }
    }

    luks = g_new0(QCryptoBlockLUKS, 1);
    block->opaque = luks;

    /* Read the entire LUKS header, minus the key material from
     * the underlying device */
    rv = readfunc(block, 0,
                  (uint8_t *)&luks->header,
                  sizeof(luks->header),
                  opaque,
                  errp);
    if (rv < 0) {
        ret = rv;
        goto fail;
    }

    /* The header is always stored in big-endian format, so
     * convert everything to native */
    be16_to_cpus(&luks->header.version);
    be32_to_cpus(&luks->header.payload_offset);
    be32_to_cpus(&luks->header.key_bytes);
    be32_to_cpus(&luks->header.master_key_iterations);

    for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
        be32_to_cpus(&luks->header.key_slots[i].active);
        be32_to_cpus(&luks->header.key_slots[i].iterations);
        be32_to_cpus(&luks->header.key_slots[i].key_offset);
        be32_to_cpus(&luks->header.key_slots[i].stripes);
    }

    if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
               QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
        error_setg(errp, "Volume is not in LUKS format");
        ret = -EINVAL;
        goto fail;
    }
    if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
        error_setg(errp, "LUKS version %" PRIu32 " is not supported",
                   luks->header.version);
        ret = -ENOTSUP;
        goto fail;
    }

    /*
     * The cipher_mode header contains a string that we have
     * to further parse, of the format
     *
     *    <cipher-mode>-<iv-generator>[:<iv-hash>]
     *
     * eg  cbc-essiv:sha256, cbc-plain64
     */
    ivgen_name = strchr(luks->header.cipher_mode, '-');
    if (!ivgen_name) {
        ret = -EINVAL;
        error_setg(errp, "Unexpected cipher mode string format %s",
                   luks->header.cipher_mode);
        goto fail;
    }
    *ivgen_name = '\0';
    ivgen_name++;

    ivhash_name = strchr(ivgen_name, ':');
    if (!ivhash_name) {
        ivhash = 0;
    } else {
        *ivhash_name = '\0';
        ivhash_name++;

        ivhash = qcrypto_block_luks_hash_name_lookup(ivhash_name,
                                                     &local_err);
        if (local_err) {
            ret = -ENOTSUP;
            error_propagate(errp, local_err);
            goto fail;
        }
    }

    ciphermode = qcrypto_block_luks_cipher_mode_lookup(luks->header.cipher_mode,
                                                       &local_err);
    if (local_err) {
        ret = -ENOTSUP;
        error_propagate(errp, local_err);
        goto fail;
    }

    cipheralg = qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
                                                      ciphermode,
                                                      luks->header.key_bytes,
                                                      &local_err);
    if (local_err) {
        ret = -ENOTSUP;
        error_propagate(errp, local_err);
        goto fail;
    }

    hash = qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
                                               &local_err);
    if (local_err) {
        ret = -ENOTSUP;
        error_propagate(errp, local_err);
        goto fail;
    }

    ivalg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
                                                 &local_err);
    if (local_err) {
        ret = -ENOTSUP;
        error_propagate(errp, local_err);
        goto fail;
    }

    if (ivalg == QCRYPTO_IVGEN_ALG_ESSIV) {
        if (!ivhash_name) {
            ret = -EINVAL;
            error_setg(errp, "Missing IV generator hash specification");
            goto fail;
        }
        ivcipheralg = qcrypto_block_luks_essiv_cipher(cipheralg,
                                                      ivhash,
                                                      &local_err);
        if (local_err) {
            ret = -ENOTSUP;
            error_propagate(errp, local_err);
            goto fail;
        }
    } else {
        /* Note we parsed the ivhash_name earlier in the cipher_mode
         * spec string even with plain/plain64 ivgens, but we
         * will ignore it, since it is irrelevant for these ivgens.
         * This is for compat with dm-crypt which will silently
         * ignore hash names with these ivgens rather than report
         * an error about the invalid usage
         */
        ivcipheralg = cipheralg;
    }

    if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
        /* Try to find which key slot our password is valid for
         * and unlock the master key from that slot.
         */
        if (qcrypto_block_luks_find_key(block,
                                        password,
                                        cipheralg, ciphermode,
                                        hash,
                                        ivalg,
                                        ivcipheralg,
                                        ivhash,
                                        &masterkey, &masterkeylen,
                                        readfunc, opaque,
                                        errp) < 0) {
            ret = -EACCES;
            goto fail;
        }

        /* We have a valid master key now, so can setup the
         * block device payload decryption objects
         */
        block->kdfhash = hash;
        block->niv = qcrypto_cipher_get_iv_len(cipheralg,
                                               ciphermode);
        block->ivgen = qcrypto_ivgen_new(ivalg,
                                         ivcipheralg,
                                         ivhash,
                                         masterkey, masterkeylen,
                                         errp);
        if (!block->ivgen) {
            ret = -ENOTSUP;
            goto fail;
        }

        block->cipher = qcrypto_cipher_new(cipheralg,
                                           ciphermode,
                                           masterkey, masterkeylen,
                                           errp);
        if (!block->cipher) {
            ret = -ENOTSUP;
            goto fail;
        }
    }

    block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
    block->payload_offset = luks->header.payload_offset *
        block->sector_size;

    luks->cipher_alg = cipheralg;
    luks->cipher_mode = ciphermode;
    luks->ivgen_alg = ivalg;
    luks->ivgen_hash_alg = ivhash;
    luks->hash_alg = hash;

    g_free(masterkey);
    g_free(password);

    return 0;

 fail:
    g_free(masterkey);
    qcrypto_cipher_free(block->cipher);
    qcrypto_ivgen_free(block->ivgen);
    g_free(luks);
    g_free(password);
    return ret;
}


static void
qcrypto_block_luks_uuid_gen(uint8_t *uuidstr)
{
    QemuUUID uuid;
    qemu_uuid_generate(&uuid);
    qemu_uuid_unparse(&uuid, (char *)uuidstr);
}

static int
qcrypto_block_luks_create(QCryptoBlock *block,
                          QCryptoBlockCreateOptions *options,
                          const char *optprefix,
                          QCryptoBlockInitFunc initfunc,
                          QCryptoBlockWriteFunc writefunc,
                          void *opaque,
                          Error **errp)
{
    QCryptoBlockLUKS *luks;
    QCryptoBlockCreateOptionsLUKS luks_opts;
    Error *local_err = NULL;
    uint8_t *masterkey = NULL;
    uint8_t *slotkey = NULL;
    uint8_t *splitkey = NULL;
    size_t splitkeylen = 0;
    size_t i;
    QCryptoCipher *cipher = NULL;
    QCryptoIVGen *ivgen = NULL;
    char *password;
    const char *cipher_alg;
    const char *cipher_mode;
    const char *ivgen_alg;
    const char *ivgen_hash_alg = NULL;
    const char *hash_alg;
    char *cipher_mode_spec = NULL;
    QCryptoCipherAlgorithm ivcipheralg = 0;
    uint64_t iters;

    memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
    if (!luks_opts.has_iter_time) {
        luks_opts.iter_time = 2000;
    }
    if (!luks_opts.has_cipher_alg) {
        luks_opts.cipher_alg = QCRYPTO_CIPHER_ALG_AES_256;
    }
    if (!luks_opts.has_cipher_mode) {
        luks_opts.cipher_mode = QCRYPTO_CIPHER_MODE_XTS;
    }
    if (!luks_opts.has_ivgen_alg) {
        luks_opts.ivgen_alg = QCRYPTO_IVGEN_ALG_PLAIN64;
    }
    if (!luks_opts.has_hash_alg) {
        luks_opts.hash_alg = QCRYPTO_HASH_ALG_SHA256;
    }
    if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
        if (!luks_opts.has_ivgen_hash_alg) {
            luks_opts.ivgen_hash_alg = QCRYPTO_HASH_ALG_SHA256;
            luks_opts.has_ivgen_hash_alg = true;
        }
    }
    /* Note we're allowing ivgen_hash_alg to be set even for
     * non-essiv iv generators that don't need a hash. It will
     * be silently ignored, for compatibility with dm-crypt */

    if (!options->u.luks.key_secret) {
        error_setg(errp, "Parameter '%skey-secret' is required for cipher",
                   optprefix ? optprefix : "");
        return -1;
    }
    password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret, errp);
    if (!password) {
        return -1;
    }

    luks = g_new0(QCryptoBlockLUKS, 1);
    block->opaque = luks;

    memcpy(luks->header.magic, qcrypto_block_luks_magic,
           QCRYPTO_BLOCK_LUKS_MAGIC_LEN);

    /* We populate the header in native endianness initially and
     * then convert everything to big endian just before writing
     * it out to disk
     */
    luks->header.version = QCRYPTO_BLOCK_LUKS_VERSION;
    qcrypto_block_luks_uuid_gen(luks->header.uuid);

    cipher_alg = qcrypto_block_luks_cipher_alg_lookup(luks_opts.cipher_alg,
                                                      errp);
    if (!cipher_alg) {
        goto error;
    }

    cipher_mode = QCryptoCipherMode_str(luks_opts.cipher_mode);
    ivgen_alg = QCryptoIVGenAlgorithm_str(luks_opts.ivgen_alg);
    if (luks_opts.has_ivgen_hash_alg) {
        ivgen_hash_alg = QCryptoHashAlgorithm_str(luks_opts.ivgen_hash_alg);
        cipher_mode_spec = g_strdup_printf("%s-%s:%s", cipher_mode, ivgen_alg,
                                           ivgen_hash_alg);
    } else {
        cipher_mode_spec = g_strdup_printf("%s-%s", cipher_mode, ivgen_alg);
    }
    hash_alg = QCryptoHashAlgorithm_str(luks_opts.hash_alg);


    if (strlen(cipher_alg) >= QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN) {
        error_setg(errp, "Cipher name '%s' is too long for LUKS header",
                   cipher_alg);
        goto error;
    }
    if (strlen(cipher_mode_spec) >= QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN) {
        error_setg(errp, "Cipher mode '%s' is too long for LUKS header",
                   cipher_mode_spec);
        goto error;
    }
    if (strlen(hash_alg) >= QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN) {
        error_setg(errp, "Hash name '%s' is too long for LUKS header",
                   hash_alg);
        goto error;
    }

    if (luks_opts.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
        ivcipheralg = qcrypto_block_luks_essiv_cipher(luks_opts.cipher_alg,
                                                      luks_opts.ivgen_hash_alg,
                                                      &local_err);
        if (local_err) {
            error_propagate(errp, local_err);
            goto error;
        }
    } else {
        ivcipheralg = luks_opts.cipher_alg;
    }

    strcpy(luks->header.cipher_name, cipher_alg);
    strcpy(luks->header.cipher_mode, cipher_mode_spec);
    strcpy(luks->header.hash_spec, hash_alg);

    luks->header.key_bytes = qcrypto_cipher_get_key_len(luks_opts.cipher_alg);
    if (luks_opts.cipher_mode == QCRYPTO_CIPHER_MODE_XTS) {
        luks->header.key_bytes *= 2;
    }

    /* Generate the salt used for hashing the master key
     * with PBKDF later
     */
    if (qcrypto_random_bytes(luks->header.master_key_salt,
                             QCRYPTO_BLOCK_LUKS_SALT_LEN,
                             errp) < 0) {
        goto error;
    }

    /* Generate random master key */
    masterkey = g_new0(uint8_t, luks->header.key_bytes);
    if (qcrypto_random_bytes(masterkey,
                             luks->header.key_bytes, errp) < 0) {
        goto error;
    }


    /* Setup the block device payload encryption objects */
    block->cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
                                       luks_opts.cipher_mode,
                                       masterkey, luks->header.key_bytes,
                                       errp);
    if (!block->cipher) {
        goto error;
    }

    block->kdfhash = luks_opts.hash_alg;
    block->niv = qcrypto_cipher_get_iv_len(luks_opts.cipher_alg,
                                           luks_opts.cipher_mode);
    block->ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
                                     ivcipheralg,
                                     luks_opts.ivgen_hash_alg,
                                     masterkey, luks->header.key_bytes,
                                     errp);

    if (!block->ivgen) {
        goto error;
    }


    /* Determine how many iterations we need to hash the master
     * key, in order to have 1 second of compute time used
     */
    iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
                                       masterkey, luks->header.key_bytes,
                                       luks->header.master_key_salt,
                                       QCRYPTO_BLOCK_LUKS_SALT_LEN,
                                       QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
                                       &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        goto error;
    }

    if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
        error_setg_errno(errp, ERANGE,
                         "PBKDF iterations %llu too large to scale",
                         (unsigned long long)iters);
        goto error;
    }

    /* iter_time was in millis, but count_iters reported for secs */
    iters = iters * luks_opts.iter_time / 1000;

    /* Why /= 8 ?  That matches cryptsetup, but there's no
     * explanation why they chose /= 8... Probably so that
     * if all 8 keyslots are active we only spend 1 second
     * in total time to check all keys */
    iters /= 8;
    if (iters > UINT32_MAX) {
        error_setg_errno(errp, ERANGE,
                         "PBKDF iterations %llu larger than %u",
                         (unsigned long long)iters, UINT32_MAX);
        goto error;
    }
    iters = MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS);
    luks->header.master_key_iterations = iters;

    /* Hash the master key, saving the result in the LUKS
     * header. This hash is used when opening the encrypted
     * device to verify that the user password unlocked a
     * valid master key
     */
    if (qcrypto_pbkdf2(luks_opts.hash_alg,
                       masterkey, luks->header.key_bytes,
                       luks->header.master_key_salt,
                       QCRYPTO_BLOCK_LUKS_SALT_LEN,
                       luks->header.master_key_iterations,
                       luks->header.master_key_digest,
                       QCRYPTO_BLOCK_LUKS_DIGEST_LEN,
                       errp) < 0) {
        goto error;
    }


    /* Although LUKS has multiple key slots, we're just going
     * to use the first key slot */
    splitkeylen = luks->header.key_bytes * QCRYPTO_BLOCK_LUKS_STRIPES;
    for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
        luks->header.key_slots[i].active = i == 0 ?
            QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED :
            QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
        luks->header.key_slots[i].stripes = QCRYPTO_BLOCK_LUKS_STRIPES;

        /* This calculation doesn't match that shown in the spec,
         * but instead follows the cryptsetup implementation.
         */
        luks->header.key_slots[i].key_offset =
            (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
             QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
            (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
                      (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
                       QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) * i);
    }

    if (qcrypto_random_bytes(luks->header.key_slots[0].salt,
                             QCRYPTO_BLOCK_LUKS_SALT_LEN,
                             errp) < 0) {
        goto error;
    }

    /* Again we determine how many iterations are required to
     * hash the user password while consuming 1 second of compute
     * time */
    iters = qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
                                       (uint8_t *)password, strlen(password),
                                       luks->header.key_slots[0].salt,
                                       QCRYPTO_BLOCK_LUKS_SALT_LEN,
                                       luks->header.key_bytes,
                                       &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        goto error;
    }

    if (iters > (ULLONG_MAX / luks_opts.iter_time)) {
        error_setg_errno(errp, ERANGE,
                         "PBKDF iterations %llu too large to scale",
                         (unsigned long long)iters);
        goto error;
    }

    /* iter_time was in millis, but count_iters reported for secs */
    iters = iters * luks_opts.iter_time / 1000;

    if (iters > UINT32_MAX) {
        error_setg_errno(errp, ERANGE,
                         "PBKDF iterations %llu larger than %u",
                         (unsigned long long)iters, UINT32_MAX);
        goto error;
    }

    luks->header.key_slots[0].iterations =
        MAX(iters, QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS);


    /* Generate a key that we'll use to encrypt the master
     * key, from the user's password
     */
    slotkey = g_new0(uint8_t, luks->header.key_bytes);
    if (qcrypto_pbkdf2(luks_opts.hash_alg,
                       (uint8_t *)password, strlen(password),
                       luks->header.key_slots[0].salt,
                       QCRYPTO_BLOCK_LUKS_SALT_LEN,
                       luks->header.key_slots[0].iterations,
                       slotkey, luks->header.key_bytes,
                       errp) < 0) {
        goto error;
    }


    /* Setup the encryption objects needed to encrypt the
     * master key material
     */
    cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
                                luks_opts.cipher_mode,
                                slotkey, luks->header.key_bytes,
                                errp);
    if (!cipher) {
        goto error;
    }

    ivgen = qcrypto_ivgen_new(luks_opts.ivgen_alg,
                              ivcipheralg,
                              luks_opts.ivgen_hash_alg,
                              slotkey, luks->header.key_bytes,
                              errp);
    if (!ivgen) {
        goto error;
    }

    /* Before storing the master key, we need to vastly
     * increase its size, as protection against forensic
     * disk data recovery */
    splitkey = g_new0(uint8_t, splitkeylen);

    if (qcrypto_afsplit_encode(luks_opts.hash_alg,
                               luks->header.key_bytes,
                               luks->header.key_slots[0].stripes,
                               masterkey,
                               splitkey,
                               errp) < 0) {
        goto error;
    }

    /* Now we encrypt the split master key with the key generated
     * from the user's password, before storing it */
    if (qcrypto_block_encrypt_helper(cipher, block->niv, ivgen,
                                     QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
                                     0,
                                     splitkey,
                                     splitkeylen,
                                     errp) < 0) {
        goto error;
    }


    /* The total size of the LUKS headers is the partition header + key
     * slot headers, rounded up to the nearest sector, combined with
     * the size of each master key material region, also rounded up
     * to the nearest sector */
    luks->header.payload_offset =
        (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE) +
        (ROUND_UP(DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE),
                  (QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
                   QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) *
         QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);

    block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
    block->payload_offset = luks->header.payload_offset *
        block->sector_size;

    /* Reserve header space to match payload offset */
    initfunc(block, block->payload_offset, opaque, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        goto error;
    }

    /* Everything on disk uses Big Endian, so flip header fields
     * before writing them */
    cpu_to_be16s(&luks->header.version);
    cpu_to_be32s(&luks->header.payload_offset);
    cpu_to_be32s(&luks->header.key_bytes);
    cpu_to_be32s(&luks->header.master_key_iterations);

    for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
        cpu_to_be32s(&luks->header.key_slots[i].active);
        cpu_to_be32s(&luks->header.key_slots[i].iterations);
        cpu_to_be32s(&luks->header.key_slots[i].key_offset);
        cpu_to_be32s(&luks->header.key_slots[i].stripes);
    }


    /* Write out the partition header and key slot headers */
    writefunc(block, 0,
              (const uint8_t *)&luks->header,
              sizeof(luks->header),
              opaque,
              &local_err);

    /* Delay checking local_err until we've byte-swapped */

    /* Byte swap the header back to native, in case we need
     * to read it again later */
    be16_to_cpus(&luks->header.version);
    be32_to_cpus(&luks->header.payload_offset);
    be32_to_cpus(&luks->header.key_bytes);
    be32_to_cpus(&luks->header.master_key_iterations);

    for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
        be32_to_cpus(&luks->header.key_slots[i].active);
        be32_to_cpus(&luks->header.key_slots[i].iterations);
        be32_to_cpus(&luks->header.key_slots[i].key_offset);
        be32_to_cpus(&luks->header.key_slots[i].stripes);
    }

    if (local_err) {
        error_propagate(errp, local_err);
        goto error;
    }

    /* Write out the master key material, starting at the
     * sector immediately following the partition header. */
    if (writefunc(block,
                  luks->header.key_slots[0].key_offset *
                  QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
                  splitkey, splitkeylen,
                  opaque,
                  errp) != splitkeylen) {
        goto error;
    }

    luks->cipher_alg = luks_opts.cipher_alg;
    luks->cipher_mode = luks_opts.cipher_mode;
    luks->ivgen_alg = luks_opts.ivgen_alg;
    luks->ivgen_hash_alg = luks_opts.ivgen_hash_alg;
    luks->hash_alg = luks_opts.hash_alg;

    memset(masterkey, 0, luks->header.key_bytes);
    g_free(masterkey);
    memset(slotkey, 0, luks->header.key_bytes);
    g_free(slotkey);
    g_free(splitkey);
    g_free(password);
    g_free(cipher_mode_spec);

    qcrypto_ivgen_free(ivgen);
    qcrypto_cipher_free(cipher);

    return 0;

 error:
    if (masterkey) {
        memset(masterkey, 0, luks->header.key_bytes);
    }
    g_free(masterkey);
    if (slotkey) {
        memset(slotkey, 0, luks->header.key_bytes);
    }
    g_free(slotkey);
    g_free(splitkey);
    g_free(password);
    g_free(cipher_mode_spec);

    qcrypto_ivgen_free(ivgen);
    qcrypto_cipher_free(cipher);

    g_free(luks);
    return -1;
}


static int qcrypto_block_luks_get_info(QCryptoBlock *block,
                                       QCryptoBlockInfo *info,
                                       Error **errp)
{
    QCryptoBlockLUKS *luks = block->opaque;
    QCryptoBlockInfoLUKSSlot *slot;
    QCryptoBlockInfoLUKSSlotList *slots = NULL, **prev = &info->u.luks.slots;
    size_t i;

    info->u.luks.cipher_alg = luks->cipher_alg;
    info->u.luks.cipher_mode = luks->cipher_mode;
    info->u.luks.ivgen_alg = luks->ivgen_alg;
    if (info->u.luks.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
        info->u.luks.has_ivgen_hash_alg = true;
        info->u.luks.ivgen_hash_alg = luks->ivgen_hash_alg;
    }
    info->u.luks.hash_alg = luks->hash_alg;
    info->u.luks.payload_offset = block->payload_offset;
    info->u.luks.master_key_iters = luks->header.master_key_iterations;
    info->u.luks.uuid = g_strndup((const char *)luks->header.uuid,
                                  sizeof(luks->header.uuid));

    for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
        slots = g_new0(QCryptoBlockInfoLUKSSlotList, 1);
        *prev = slots;

        slots->value = slot = g_new0(QCryptoBlockInfoLUKSSlot, 1);
        slot->active = luks->header.key_slots[i].active ==
            QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
        slot->key_offset = luks->header.key_slots[i].key_offset
             * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
        if (slot->active) {
            slot->has_iters = true;
            slot->iters = luks->header.key_slots[i].iterations;
            slot->has_stripes = true;
            slot->stripes = luks->header.key_slots[i].stripes;
        }

        prev = &slots->next;
    }

    return 0;
}


static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
{
    g_free(block->opaque);
}


static int
qcrypto_block_luks_decrypt(QCryptoBlock *block,
                           uint64_t offset,
                           uint8_t *buf,
                           size_t len,
                           Error **errp)
{
    assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
    assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
    return qcrypto_block_decrypt_helper(block->cipher,
                                        block->niv, block->ivgen,
                                        QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
                                        offset, buf, len, errp);
}


static int
qcrypto_block_luks_encrypt(QCryptoBlock *block,
                           uint64_t offset,
                           uint8_t *buf,
                           size_t len,
                           Error **errp)
{
    assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
    assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE));
    return qcrypto_block_encrypt_helper(block->cipher,
                                        block->niv, block->ivgen,
                                        QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
                                        offset, buf, len, errp);
}


const QCryptoBlockDriver qcrypto_block_driver_luks = {
    .open = qcrypto_block_luks_open,
    .create = qcrypto_block_luks_create,
    .get_info = qcrypto_block_luks_get_info,
    .cleanup = qcrypto_block_luks_cleanup,
    .decrypt = qcrypto_block_luks_decrypt,
    .encrypt = qcrypto_block_luks_encrypt,
    .has_format = qcrypto_block_luks_has_format,
};