-
Notifications
You must be signed in to change notification settings - Fork 36
/
Copy pathblock-luks.c
1969 lines (1717 loc) · 65 KB
/
block-luks.c
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
/*
* 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 2.1 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 "block-luks-priv.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/bitmap.h"
#include "qemu/range.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 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 },
};
#ifdef CONFIG_CRYPTO_SM4
static const QCryptoBlockLUKSCipherSizeMap
qcrypto_block_luks_cipher_size_map_sm4[] = {
{ 16, QCRYPTO_CIPHER_ALG_SM4},
{ 0, 0 },
};
#endif
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 },
#ifdef CONFIG_CRYPTO_SM4
{ "sm4", qcrypto_block_luks_cipher_size_map_sm4},
#endif
};
QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSKeySlot) != 48);
QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSHeader) != 592);
struct QCryptoBlockLUKS {
QCryptoBlockLUKSHeader header;
/* Main encryption algorithm used for encryption*/
QCryptoCipherAlgorithm cipher_alg;
/* Mode of encryption for the selected encryption algorithm */
QCryptoCipherMode cipher_mode;
/* Initialization vector generation algorithm */
QCryptoIVGenAlgorithm ivgen_alg;
/* Hash algorithm used for IV generation*/
QCryptoHashAlgorithm ivgen_hash_alg;
/*
* Encryption algorithm used for IV generation.
* Usually the same as main encryption algorithm
*/
QCryptoCipherAlgorithm ivgen_cipher_alg;
/* Hash algorithm used in pbkdf2 function */
QCryptoHashAlgorithm hash_alg;
/* Name of the secret that was used to open the image */
char *secret;
};
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, because 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;
}
}
/*
* Returns number of sectors needed to store the key material
* given number of anti forensic stripes
*/
static int
qcrypto_block_luks_splitkeylen_sectors(const QCryptoBlockLUKS *luks,
unsigned int header_sectors,
unsigned int stripes)
{
/*
* This calculation doesn't match that shown in the spec,
* but instead follows the cryptsetup implementation.
*/
size_t splitkeylen = luks->header.master_key_len * stripes;
/* First align the key material size to block size*/
size_t splitkeylen_sectors =
DIV_ROUND_UP(splitkeylen, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE);
/* Then also align the key material size to the size of the header */
return ROUND_UP(splitkeylen_sectors, header_sectors);
}
void
qcrypto_block_luks_to_disk_endian(QCryptoBlockLUKSHeader *hdr)
{
size_t i;
/*
* Everything on disk uses Big Endian (tm), so flip header fields
* before writing them
*/
cpu_to_be16s(&hdr->version);
cpu_to_be32s(&hdr->payload_offset_sector);
cpu_to_be32s(&hdr->master_key_len);
cpu_to_be32s(&hdr->master_key_iterations);
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
cpu_to_be32s(&hdr->key_slots[i].active);
cpu_to_be32s(&hdr->key_slots[i].iterations);
cpu_to_be32s(&hdr->key_slots[i].key_offset_sector);
cpu_to_be32s(&hdr->key_slots[i].stripes);
}
}
void
qcrypto_block_luks_from_disk_endian(QCryptoBlockLUKSHeader *hdr)
{
size_t i;
/*
* The header is always stored in big-endian format, so
* convert everything to native
*/
be16_to_cpus(&hdr->version);
be32_to_cpus(&hdr->payload_offset_sector);
be32_to_cpus(&hdr->master_key_len);
be32_to_cpus(&hdr->master_key_iterations);
for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
be32_to_cpus(&hdr->key_slots[i].active);
be32_to_cpus(&hdr->key_slots[i].iterations);
be32_to_cpus(&hdr->key_slots[i].key_offset_sector);
be32_to_cpus(&hdr->key_slots[i].stripes);
}
}
/*
* Stores the main LUKS header, taking care of endianness
*/
static int
qcrypto_block_luks_store_header(QCryptoBlock *block,
QCryptoBlockWriteFunc writefunc,
void *opaque,
Error **errp)
{
const QCryptoBlockLUKS *luks = block->opaque;
Error *local_err = NULL;
g_autofree QCryptoBlockLUKSHeader *hdr_copy = NULL;
/* Create a copy of the header */
hdr_copy = g_new0(QCryptoBlockLUKSHeader, 1);
memcpy(hdr_copy, &luks->header, sizeof(QCryptoBlockLUKSHeader));
qcrypto_block_luks_to_disk_endian(hdr_copy);
/* Write out the partition header and key slot headers */
writefunc(block, 0, (const uint8_t *)hdr_copy, sizeof(*hdr_copy),
opaque, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
return 0;
}
/*
* Loads the main LUKS header, and byteswaps it to native endianness
* And run basic sanity checks on it
*/
static int
qcrypto_block_luks_load_header(QCryptoBlock *block,
QCryptoBlockReadFunc readfunc,
void *opaque,
Error **errp)
{
int rv;
QCryptoBlockLUKS *luks = block->opaque;
/*
* 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) {
return rv;
}
qcrypto_block_luks_from_disk_endian(&luks->header);
return 0;
}
/*
* Does basic sanity checks on the LUKS header
*/
static int
qcrypto_block_luks_check_header(const QCryptoBlockLUKS *luks,
unsigned int flags,
Error **errp)
{
size_t i, j;
unsigned int header_sectors = QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET /
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
bool detached = flags & QCRYPTO_BLOCK_OPEN_DETACHED;
if (memcmp(luks->header.magic, qcrypto_block_luks_magic,
QCRYPTO_BLOCK_LUKS_MAGIC_LEN) != 0) {
error_setg(errp, "Volume is not in LUKS format");
return -1;
}
if (luks->header.version != QCRYPTO_BLOCK_LUKS_VERSION) {
error_setg(errp, "LUKS version %" PRIu32 " is not supported",
luks->header.version);
return -1;
}
if (!memchr(luks->header.cipher_name, '\0',
sizeof(luks->header.cipher_name))) {
error_setg(errp, "LUKS header cipher name is not NUL terminated");
return -1;
}
if (!memchr(luks->header.cipher_mode, '\0',
sizeof(luks->header.cipher_mode))) {
error_setg(errp, "LUKS header cipher mode is not NUL terminated");
return -1;
}
if (!memchr(luks->header.hash_spec, '\0',
sizeof(luks->header.hash_spec))) {
error_setg(errp, "LUKS header hash spec is not NUL terminated");
return -1;
}
if (!detached && luks->header.payload_offset_sector <
DIV_ROUND_UP(QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) {
error_setg(errp, "LUKS payload is overlapping with the header");
return -1;
}
if (luks->header.master_key_iterations == 0) {
error_setg(errp, "LUKS key iteration count is zero");
return -1;
}
/* Check all keyslots for corruption */
for (i = 0 ; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS ; i++) {
const QCryptoBlockLUKSKeySlot *slot1 = &luks->header.key_slots[i];
unsigned int start1 = slot1->key_offset_sector;
unsigned int len1 =
qcrypto_block_luks_splitkeylen_sectors(luks,
header_sectors,
slot1->stripes);
if (slot1->stripes != QCRYPTO_BLOCK_LUKS_STRIPES) {
error_setg(errp, "Keyslot %zu is corrupted (stripes %d != %d)",
i, slot1->stripes, QCRYPTO_BLOCK_LUKS_STRIPES);
return -1;
}
if (slot1->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED &&
slot1->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
error_setg(errp,
"Keyslot %zu state (active/disable) is corrupted", i);
return -1;
}
if (slot1->active == QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED &&
slot1->iterations == 0) {
error_setg(errp, "Keyslot %zu iteration count is zero", i);
return -1;
}
if (start1 < DIV_ROUND_UP(QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE)) {
error_setg(errp,
"Keyslot %zu is overlapping with the LUKS header",
i);
return -1;
}
if (!detached && start1 + len1 > luks->header.payload_offset_sector) {
error_setg(errp,
"Keyslot %zu is overlapping with the encrypted payload",
i);
return -1;
}
for (j = i + 1 ; j < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS ; j++) {
const QCryptoBlockLUKSKeySlot *slot2 = &luks->header.key_slots[j];
unsigned int start2 = slot2->key_offset_sector;
unsigned int len2 =
qcrypto_block_luks_splitkeylen_sectors(luks,
header_sectors,
slot2->stripes);
if (ranges_overlap(start1, len1, start2, len2)) {
error_setg(errp,
"Keyslots %zu and %zu are overlapping in the header",
i, j);
return -1;
}
}
}
return 0;
}
/*
* Parses the crypto parameters that are stored in the LUKS header
*/
static int
qcrypto_block_luks_parse_header(QCryptoBlockLUKS *luks, Error **errp)
{
g_autofree char *cipher_mode = g_strdup(luks->header.cipher_mode);
char *ivgen_name, *ivhash_name;
Error *local_err = NULL;
/*
* 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(cipher_mode, '-');
if (!ivgen_name) {
error_setg(errp, "Unexpected cipher mode string format '%s'",
luks->header.cipher_mode);
return -1;
}
*ivgen_name = '\0';
ivgen_name++;
ivhash_name = strchr(ivgen_name, ':');
if (!ivhash_name) {
luks->ivgen_hash_alg = 0;
} else {
*ivhash_name = '\0';
ivhash_name++;
luks->ivgen_hash_alg = qcrypto_block_luks_hash_name_lookup(ivhash_name,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
}
luks->cipher_mode = qcrypto_block_luks_cipher_mode_lookup(cipher_mode,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
luks->cipher_alg =
qcrypto_block_luks_cipher_name_lookup(luks->header.cipher_name,
luks->cipher_mode,
luks->header.master_key_len,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
luks->hash_alg =
qcrypto_block_luks_hash_name_lookup(luks->header.hash_spec,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
luks->ivgen_alg = qcrypto_block_luks_ivgen_name_lookup(ivgen_name,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
if (luks->ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
if (!ivhash_name) {
error_setg(errp, "Missing IV generator hash specification");
return -1;
}
luks->ivgen_cipher_alg =
qcrypto_block_luks_essiv_cipher(luks->cipher_alg,
luks->ivgen_hash_alg,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
return -1;
}
} 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
*/
luks->ivgen_cipher_alg = luks->cipher_alg;
}
return 0;
}
/*
* Given a key slot, user password, and the master key,
* will store the encrypted master key there, and update the
* in-memory header. User must then write the in-memory header
*
* Returns:
* 0 if the keyslot was written successfully
* with the provided password
* -1 if a fatal error occurred while storing the key
*/
static int
qcrypto_block_luks_store_key(QCryptoBlock *block,
unsigned int slot_idx,
const char *password,
uint8_t *masterkey,
uint64_t iter_time,
QCryptoBlockWriteFunc writefunc,
void *opaque,
Error **errp)
{
QCryptoBlockLUKS *luks = block->opaque;
QCryptoBlockLUKSKeySlot *slot;
g_autofree uint8_t *splitkey = NULL;
size_t splitkeylen;
g_autofree uint8_t *slotkey = NULL;
g_autoptr(QCryptoCipher) cipher = NULL;
g_autoptr(QCryptoIVGen) ivgen = NULL;
Error *local_err = NULL;
uint64_t iters;
int ret = -1;
assert(slot_idx < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
slot = &luks->header.key_slots[slot_idx];
splitkeylen = luks->header.master_key_len * slot->stripes;
if (qcrypto_random_bytes(slot->salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
errp) < 0) {
goto cleanup;
}
/*
* Determine how many iterations are required to
* hash the user password while consuming 1 second of compute
* time
*/
iters = qcrypto_pbkdf2_count_iters(luks->hash_alg,
(uint8_t *)password, strlen(password),
slot->salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
luks->header.master_key_len,
&local_err);
if (local_err) {
error_propagate(errp, local_err);
goto cleanup;
}
if (iters > (ULLONG_MAX / iter_time)) {
error_setg_errno(errp, ERANGE,
"PBKDF iterations %llu too large to scale",
(unsigned long long)iters);
goto cleanup;
}
/* iter_time was in millis, but count_iters reported for secs */
iters = iters * 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 cleanup;
}
slot->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.master_key_len);
if (qcrypto_pbkdf2(luks->hash_alg,
(uint8_t *)password, strlen(password),
slot->salt,
QCRYPTO_BLOCK_LUKS_SALT_LEN,
slot->iterations,
slotkey, luks->header.master_key_len,
errp) < 0) {
goto cleanup;
}
/*
* Setup the encryption objects needed to encrypt the
* master key material
*/
cipher = qcrypto_cipher_new(luks->cipher_alg,
luks->cipher_mode,
slotkey, luks->header.master_key_len,
errp);
if (!cipher) {
goto cleanup;
}
ivgen = qcrypto_ivgen_new(luks->ivgen_alg,
luks->ivgen_cipher_alg,
luks->ivgen_hash_alg,
slotkey, luks->header.master_key_len,
errp);
if (!ivgen) {
goto cleanup;
}
/*
* 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->hash_alg,
luks->header.master_key_len,
slot->stripes,
masterkey,
splitkey,
errp) < 0) {
goto cleanup;
}
/*
* Now we encrypt the split master key with the key generated
* from the user's password, before storing it
*/
if (qcrypto_block_cipher_encrypt_helper(cipher, block->niv, ivgen,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
0,
splitkey,
splitkeylen,
errp) < 0) {
goto cleanup;
}
/* Write out the slot's master key material. */
if (writefunc(block,
slot->key_offset_sector *
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
splitkey, splitkeylen,
opaque,
errp) < 0) {
goto cleanup;
}
slot->active = QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
if (qcrypto_block_luks_store_header(block, writefunc, opaque, errp) < 0) {
goto cleanup;
}
ret = 0;
cleanup:
if (slotkey) {
memset(slotkey, 0, luks->header.master_key_len);
}
if (splitkey) {
memset(splitkey, 0, splitkeylen);
}
return ret;
}
/*
* 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,
size_t slot_idx,
const char *password,
uint8_t *masterkey,
QCryptoBlockReadFunc readfunc,
void *opaque,
Error **errp)
{
QCryptoBlockLUKS *luks = block->opaque;
const QCryptoBlockLUKSKeySlot *slot;
g_autofree uint8_t *splitkey = NULL;
size_t splitkeylen;
g_autofree uint8_t *possiblekey = NULL;
int rv;
g_autoptr(QCryptoCipher) cipher = NULL;
uint8_t keydigest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
g_autoptr(QCryptoIVGen) ivgen = NULL;
size_t niv;
assert(slot_idx < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
slot = &luks->header.key_slots[slot_idx];
if (slot->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
return 0;
}
splitkeylen = luks->header.master_key_len * slot->stripes;
splitkey = g_new0(uint8_t, splitkeylen);
possiblekey = g_new0(uint8_t, luks->header.master_key_len);
/*
* 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(luks->hash_alg,
(const uint8_t *)password, strlen(password),
slot->salt, QCRYPTO_BLOCK_LUKS_SALT_LEN,
slot->iterations,
possiblekey, luks->header.master_key_len,
errp) < 0) {
return -1;
}
/*
* 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_sector * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
splitkey, splitkeylen,
opaque,
errp);
if (rv < 0) {
return -1;
}
/* Setup the cipher/ivgen that we'll use to try to decrypt
* the split master key material */
cipher = qcrypto_cipher_new(luks->cipher_alg,
luks->cipher_mode,
possiblekey,
luks->header.master_key_len,
errp);
if (!cipher) {
return -1;
}
niv = qcrypto_cipher_get_iv_len(luks->cipher_alg,
luks->cipher_mode);
ivgen = qcrypto_ivgen_new(luks->ivgen_alg,
luks->ivgen_cipher_alg,
luks->ivgen_hash_alg,
possiblekey,
luks->header.master_key_len,
errp);
if (!ivgen) {
return -1;
}
/*
* 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_cipher_decrypt_helper(cipher,
niv,
ivgen,
QCRYPTO_BLOCK_LUKS_SECTOR_SIZE,
0,
splitkey,
splitkeylen,
errp) < 0) {
return -1;
}
/*
* Now we've decrypted the split master key, join
* it back together to get the actual master key.
*/
if (qcrypto_afsplit_decode(luks->hash_alg,
luks->header.master_key_len,
slot->stripes,
splitkey,
masterkey,
errp) < 0) {
return -1;
}
/*
* 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