aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/md/dm-crypt.c
blob: 81b0fa66045204604a979fdc929e723f6c914a5c (plain) (blame)
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
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
/*
 * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
 * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
 * Copyright (C) 2006-2009 Red Hat, Inc. All rights reserved.
 * Copyright (C) 2013 Milan Broz <gmazyland@gmail.com>
 *
 * This file is released under the GPL.
 */

#include <linux/completion.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/mempool.h>
#include <linux/slab.h>
#include <linux/crypto.h>
#include <linux/workqueue.h>
#include <linux/backing-dev.h>
#include <linux/percpu.h>
#include <linux/atomic.h>
#include <linux/scatterlist.h>
#include <asm/page.h>
#include <asm/unaligned.h>
#include <crypto/hash.h>
#include <crypto/md5.h>
#include <crypto/algapi.h>

#include <linux/device-mapper.h>

#define DM_MSG_PREFIX "crypt"

/*
 * context holding the current state of a multi-part conversion
 */
struct convert_context {
	struct completion restart;
	struct bio *bio_in;
	struct bio *bio_out;
	unsigned int offset_in;
	unsigned int offset_out;
	unsigned int idx_in;
	unsigned int idx_out;
	sector_t cc_sector;
	atomic_t cc_pending;
};

/*
 * per bio private data
 */
struct dm_crypt_io {
	struct crypt_config *cc;
	struct bio *base_bio;
	struct work_struct work;

	struct convert_context ctx;

	atomic_t io_pending;
	int error;
	sector_t sector;
	struct dm_crypt_io *base_io;
};

struct dm_crypt_request {
	struct convert_context *ctx;
	struct scatterlist sg_in;
	struct scatterlist sg_out;
	sector_t iv_sector;
};

struct crypt_config;

struct crypt_iv_operations {
	int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
		   const char *opts);
	void (*dtr)(struct crypt_config *cc);
	int (*init)(struct crypt_config *cc);
	int (*wipe)(struct crypt_config *cc);
	int (*generator)(struct crypt_config *cc, u8 *iv,
			 struct dm_crypt_request *dmreq);
	int (*post)(struct crypt_config *cc, u8 *iv,
		    struct dm_crypt_request *dmreq);
};

struct iv_essiv_private {
	struct crypto_hash *hash_tfm;
	u8 *salt;
};

struct iv_benbi_private {
	int shift;
};

#define LMK_SEED_SIZE 64 /* hash + 0 */
struct iv_lmk_private {
	struct crypto_shash *hash_tfm;
	u8 *seed;
};

#define TCW_WHITENING_SIZE 16
struct iv_tcw_private {
	struct crypto_shash *crc32_tfm;
	u8 *iv_seed;
	u8 *whitening;
};

/*
 * Crypt: maps a linear range of a block device
 * and encrypts / decrypts at the same time.
 */
enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };

/*
 * Duplicated per-CPU state for cipher.
 */
struct crypt_cpu {
	struct ablkcipher_request *req;
};

/*
 * The fields in here must be read only after initialization,
 * changing state should be in crypt_cpu.
 */
struct crypt_config {
	struct dm_dev *dev;
	sector_t start;

	/*
	 * pool for per bio private data, crypto requests and
	 * encryption requeusts/buffer pages
	 */
	mempool_t *io_pool;
	mempool_t *req_pool;
	mempool_t *page_pool;
	struct bio_set *bs;

	struct workqueue_struct *io_queue;
	struct workqueue_struct *crypt_queue;

	char *cipher;
	char *cipher_string;

	struct crypt_iv_operations *iv_gen_ops;
	union {
		struct iv_essiv_private essiv;
		struct iv_benbi_private benbi;
		struct iv_lmk_private lmk;
		struct iv_tcw_private tcw;
	} iv_gen_private;
	sector_t iv_offset;
	unsigned int iv_size;

	/*
	 * Duplicated per cpu state. Access through
	 * per_cpu_ptr() only.
	 */
	struct crypt_cpu __percpu *cpu;

	/* ESSIV: struct crypto_cipher *essiv_tfm */
	void *iv_private;
	struct crypto_ablkcipher **tfms;
	unsigned tfms_count;

	/*
	 * Layout of each crypto request:
	 *
	 *   struct ablkcipher_request
	 *      context
	 *      padding
	 *   struct dm_crypt_request
	 *      padding
	 *   IV
	 *
	 * The padding is added so that dm_crypt_request and the IV are
	 * correctly aligned.
	 */
	unsigned int dmreq_start;

	unsigned long flags;
	unsigned int key_size;
	unsigned int key_parts;      /* independent parts in key buffer */
	unsigned int key_extra_size; /* additional keys length */
	u8 key[0];
};

#define MIN_IOS        16
#define MIN_POOL_PAGES 32

static struct kmem_cache *_crypt_io_pool;

static void clone_init(struct dm_crypt_io *, struct bio *);
static void kcryptd_queue_crypt(struct dm_crypt_io *io);
static u8 *iv_of_dmreq(struct crypt_config *cc, struct dm_crypt_request *dmreq);

static struct crypt_cpu *this_crypt_config(struct crypt_config *cc)
{
	return this_cpu_ptr(cc->cpu);
}

/*
 * Use this to access cipher attributes that are the same for each CPU.
 */
static struct crypto_ablkcipher *any_tfm(struct crypt_config *cc)
{
	return cc->tfms[0];
}

/*
 * Different IV generation algorithms:
 *
 * plain: the initial vector is the 32-bit little-endian version of the sector
 *        number, padded with zeros if necessary.
 *
 * plain64: the initial vector is the 64-bit little-endian version of the sector
 *        number, padded with zeros if necessary.
 *
 * essiv: "encrypted sector|salt initial vector", the sector number is
 *        encrypted with the bulk cipher using a salt as key. The salt
 *        should be derived from the bulk cipher's key via hashing.
 *
 * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
 *        (needed for LRW-32-AES and possible other narrow block modes)
 *
 * null: the initial vector is always zero.  Provides compatibility with
 *       obsolete loop_fish2 devices.  Do not use for new devices.
 *
 * lmk:  Compatible implementation of the block chaining mode used
 *       by the Loop-AES block device encryption system
 *       designed by Jari Ruusu. See http://loop-aes.sourceforge.net/
 *       It operates on full 512 byte sectors and uses CBC
 *       with an IV derived from the sector number, the data and
 *       optionally extra IV seed.
 *       This means that after decryption the first block
 *       of sector must be tweaked according to decrypted data.
 *       Loop-AES can use three encryption schemes:
 *         version 1: is plain aes-cbc mode
 *         version 2: uses 64 multikey scheme with lmk IV generator
 *         version 3: the same as version 2 with additional IV seed
 *                   (it uses 65 keys, last key is used as IV seed)
 *
 * tcw:  Compatible implementation of the block chaining mode used
 *       by the TrueCrypt device encryption system (prior to version 4.1).
 *       For more info see: http://www.truecrypt.org
 *       It operates on full 512 byte sectors and uses CBC
 *       with an IV derived from initial key and the sector number.
 *       In addition, whitening value is applied on every sector, whitening
 *       is calculated from initial key, sector number and mixed using CRC32.
 *       Note that this encryption scheme is vulnerable to watermarking attacks
 *       and should be used for old compatible containers access only.
 *
 * plumb: unimplemented, see:
 * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 */

static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv,
			      struct dm_crypt_request *dmreq)
{
	memset(iv, 0, cc->iv_size);
	*(__le32 *)iv = cpu_to_le32(dmreq->iv_sector & 0xffffffff);

	return 0;
}

static int crypt_iv_plain64_gen(struct crypt_config *cc, u8 *iv,
				struct dm_crypt_request *dmreq)
{
	memset(iv, 0, cc->iv_size);
	*(__le64 *)iv = cpu_to_le64(dmreq->iv_sector);

	return 0;
}

/* Initialise ESSIV - compute salt but no local memory allocations */
static int crypt_iv_essiv_init(struct crypt_config *cc)
{
	struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
	struct hash_desc desc;
	struct scatterlist sg;
	struct crypto_cipher *essiv_tfm;
	int err;

	sg_init_one(&sg, cc->key, cc->key_size);
	desc.tfm = essiv->hash_tfm;
	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;

	err = crypto_hash_digest(&desc, &sg, cc->key_size, essiv->salt);
	if (err)
		return err;

	essiv_tfm = cc->iv_private;

	err = crypto_cipher_setkey(essiv_tfm, essiv->salt,
			    crypto_hash_digestsize(essiv->hash_tfm));
	if (err)
		return err;

	return 0;
}

/* Wipe salt and reset key derived from volume key */
static int crypt_iv_essiv_wipe(struct crypt_config *cc)
{
	struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
	unsigned salt_size = crypto_hash_digestsize(essiv->hash_tfm);
	struct crypto_cipher *essiv_tfm;
	int r, err = 0;

	memset(essiv->salt, 0, salt_size);

	essiv_tfm = cc->iv_private;
	r = crypto_cipher_setkey(essiv_tfm, essiv->salt, salt_size);
	if (r)
		err = r;

	return err;
}

/* Set up per cpu cipher state */
static struct crypto_cipher *setup_essiv_cpu(struct crypt_config *cc,
					     struct dm_target *ti,
					     u8 *salt, unsigned saltsize)
{
	struct crypto_cipher *essiv_tfm;
	int err;

	/* Setup the essiv_tfm with the given salt */
	essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(essiv_tfm)) {
		ti->error = "Error allocating crypto tfm for ESSIV";
		return essiv_tfm;
	}

	if (crypto_cipher_blocksize(essiv_tfm) !=
	    crypto_ablkcipher_ivsize(any_tfm(cc))) {
		ti->error = "Block size of ESSIV cipher does "
			    "not match IV size of block cipher";
		crypto_free_cipher(essiv_tfm);
		return ERR_PTR(-EINVAL);
	}

	err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
	if (err) {
		ti->error = "Failed to set key for ESSIV cipher";
		crypto_free_cipher(essiv_tfm);
		return ERR_PTR(err);
	}

	return essiv_tfm;
}

static void crypt_iv_essiv_dtr(struct crypt_config *cc)
{
	struct crypto_cipher *essiv_tfm;
	struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;

	crypto_free_hash(essiv->hash_tfm);
	essiv->hash_tfm = NULL;

	kzfree(essiv->salt);
	essiv->salt = NULL;

	essiv_tfm = cc->iv_private;

	if (essiv_tfm)
		crypto_free_cipher(essiv_tfm);

	cc->iv_private = NULL;
}

static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
			      const char *opts)
{
	struct crypto_cipher *essiv_tfm = NULL;
	struct crypto_hash *hash_tfm = NULL;
	u8 *salt = NULL;
	int err;

	if (!opts) {
		ti->error = "Digest algorithm missing for ESSIV mode";
		return -EINVAL;
	}

	/* Allocate hash algorithm */
	hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(hash_tfm)) {
		ti->error = "Error initializing ESSIV hash";
		err = PTR_ERR(hash_tfm);
		goto bad;
	}

	salt = kzalloc(crypto_hash_digestsize(hash_tfm), GFP_KERNEL);
	if (!salt) {
		ti->error = "Error kmallocing salt storage in ESSIV";
		err = -ENOMEM;
		goto bad;
	}

	cc->iv_gen_private.essiv.salt = salt;
	cc->iv_gen_private.essiv.hash_tfm = hash_tfm;

	essiv_tfm = setup_essiv_cpu(cc, ti, salt,
				crypto_hash_digestsize(hash_tfm));
	if (IS_ERR(essiv_tfm)) {
		crypt_iv_essiv_dtr(cc);
		return PTR_ERR(essiv_tfm);
	}
	cc->iv_private = essiv_tfm;

	return 0;

bad:
	if (hash_tfm && !IS_ERR(hash_tfm))
		crypto_free_hash(hash_tfm);
	kfree(salt);
	return err;
}

static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv,
			      struct dm_crypt_request *dmreq)
{
	struct crypto_cipher *essiv_tfm = cc->iv_private;

	memset(iv, 0, cc->iv_size);
	*(__le64 *)iv = cpu_to_le64(dmreq->iv_sector);
	crypto_cipher_encrypt_one(essiv_tfm, iv, iv);

	return 0;
}

static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
			      const char *opts)
{
	unsigned bs = crypto_ablkcipher_blocksize(any_tfm(cc));
	int log = ilog2(bs);

	/* we need to calculate how far we must shift the sector count
	 * to get the cipher block count, we use this shift in _gen */

	if (1 << log != bs) {
		ti->error = "cypher blocksize is not a power of 2";
		return -EINVAL;
	}

	if (log > 9) {
		ti->error = "cypher blocksize is > 512";
		return -EINVAL;
	}

	cc->iv_gen_private.benbi.shift = 9 - log;

	return 0;
}

static void crypt_iv_benbi_dtr(struct crypt_config *cc)
{
}

static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv,
			      struct dm_crypt_request *dmreq)
{
	__be64 val;

	memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */

	val = cpu_to_be64(((u64)dmreq->iv_sector << cc->iv_gen_private.benbi.shift) + 1);
	put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));

	return 0;
}

static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv,
			     struct dm_crypt_request *dmreq)
{
	memset(iv, 0, cc->iv_size);

	return 0;
}

static void crypt_iv_lmk_dtr(struct crypt_config *cc)
{
	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;

	if (lmk->hash_tfm && !IS_ERR(lmk->hash_tfm))
		crypto_free_shash(lmk->hash_tfm);
	lmk->hash_tfm = NULL;

	kzfree(lmk->seed);
	lmk->seed = NULL;
}

static int crypt_iv_lmk_ctr(struct crypt_config *cc, struct dm_target *ti,
			    const char *opts)
{
	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;

	lmk->hash_tfm = crypto_alloc_shash("md5", 0, 0);
	if (IS_ERR(lmk->hash_tfm)) {
		ti->error = "Error initializing LMK hash";
		return PTR_ERR(lmk->hash_tfm);
	}

	/* No seed in LMK version 2 */
	if (cc->key_parts == cc->tfms_count) {
		lmk->seed = NULL;
		return 0;
	}

	lmk->seed = kzalloc(LMK_SEED_SIZE, GFP_KERNEL);
	if (!lmk->seed) {
		crypt_iv_lmk_dtr(cc);
		ti->error = "Error kmallocing seed storage in LMK";
		return -ENOMEM;
	}

	return 0;
}

static int crypt_iv_lmk_init(struct crypt_config *cc)
{
	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
	int subkey_size = cc->key_size / cc->key_parts;

	/* LMK seed is on the position of LMK_KEYS + 1 key */
	if (lmk->seed)
		memcpy(lmk->seed, cc->key + (cc->tfms_count * subkey_size),
		       crypto_shash_digestsize(lmk->hash_tfm));

	return 0;
}

static int crypt_iv_lmk_wipe(struct crypt_config *cc)
{
	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;

	if (lmk->seed)
		memset(lmk->seed, 0, LMK_SEED_SIZE);

	return 0;
}

static int crypt_iv_lmk_one(struct crypt_config *cc, u8 *iv,
			    struct dm_crypt_request *dmreq,
			    u8 *data)
{
	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
	struct {
		struct shash_desc desc;
		char ctx[crypto_shash_descsize(lmk->hash_tfm)];
	} sdesc;
	struct md5_state md5state;
	__le32 buf[4];
	int i, r;

	sdesc.desc.tfm = lmk->hash_tfm;
	sdesc.desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;

	r = crypto_shash_init(&sdesc.desc);
	if (r)
		return r;

	if (lmk->seed) {
		r = crypto_shash_update(&sdesc.desc, lmk->seed, LMK_SEED_SIZE);
		if (r)
			return r;
	}

	/* Sector is always 512B, block size 16, add data of blocks 1-31 */
	r = crypto_shash_update(&sdesc.desc, data + 16, 16 * 31);
	if (r)
		return r;

	/* Sector is cropped to 56 bits here */
	buf[0] = cpu_to_le32(dmreq->iv_sector & 0xFFFFFFFF);
	buf[1] = cpu_to_le32((((u64)dmreq->iv_sector >> 32) & 0x00FFFFFF) | 0x80000000);
	buf[2] = cpu_to_le32(4024);
	buf[3] = 0;
	r = crypto_shash_update(&sdesc.desc, (u8 *)buf, sizeof(buf));
	if (r)
		return r;

	/* No MD5 padding here */
	r = crypto_shash_export(&sdesc.desc, &md5state);
	if (r)
		return r;

	for (i = 0; i < MD5_HASH_WORDS; i++)
		__cpu_to_le32s(&md5state.hash[i]);
	memcpy(iv, &md5state.hash, cc->iv_size);

	return 0;
}

static int crypt_iv_lmk_gen(struct crypt_config *cc, u8 *iv,
			    struct dm_crypt_request *dmreq)
{
	u8 *src;
	int r = 0;

	if (bio_data_dir(dmreq->ctx->bio_in) == WRITE) {
		src = kmap_atomic(sg_page(&dmreq->sg_in));
		r = crypt_iv_lmk_one(cc, iv, dmreq, src + dmreq->sg_in.offset);
		kunmap_atomic(src);
	} else
		memset(iv, 0, cc->iv_size);

	return r;
}

static int crypt_iv_lmk_post(struct crypt_config *cc, u8 *iv,
			     struct dm_crypt_request *dmreq)
{
	u8 *dst;
	int r;

	if (bio_data_dir(dmreq->ctx->bio_in) == WRITE)
		return 0;

	dst = kmap_atomic(sg_page(&dmreq->sg_out));
	r = crypt_iv_lmk_one(cc, iv, dmreq, dst + dmreq->sg_out.offset);

	/* Tweak the first block of plaintext sector */
	if (!r)
		crypto_xor(dst + dmreq->sg_out.offset, iv, cc->iv_size);

	kunmap_atomic(dst);
	return r;
}

static void crypt_iv_tcw_dtr(struct crypt_config *cc)
{
	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;

	kzfree(tcw->iv_seed);
	tcw->iv_seed = NULL;
	kzfree(tcw->whitening);
	tcw->whitening = NULL;

	if (tcw->crc32_tfm && !IS_ERR(tcw->crc32_tfm))
		crypto_free_shash(tcw->crc32_tfm);
	tcw->crc32_tfm = NULL;
}

static int crypt_iv_tcw_ctr(struct crypt_config *cc, struct dm_target *ti,
			    const char *opts)
{
	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;

	if (cc->key_size <= (cc->iv_size + TCW_WHITENING_SIZE)) {
		ti->error = "Wrong key size for TCW";
		return -EINVAL;
	}

	tcw->crc32_tfm = crypto_alloc_shash("crc32", 0, 0);
	if (IS_ERR(tcw->crc32_tfm)) {
		ti->error = "Error initializing CRC32 in TCW";
		return PTR_ERR(tcw->crc32_tfm);
	}

	tcw->iv_seed = kzalloc(cc->iv_size, GFP_KERNEL);
	tcw->whitening = kzalloc(TCW_WHITENING_SIZE, GFP_KERNEL);
	if (!tcw->iv_seed || !tcw->whitening) {
		crypt_iv_tcw_dtr(cc);
		ti->error = "Error allocating seed storage in TCW";
		return -ENOMEM;
	}

	return 0;
}

static int crypt_iv_tcw_init(struct crypt_config *cc)
{
	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
	int key_offset = cc->key_size - cc->iv_size - TCW_WHITENING_SIZE;

	memcpy(tcw->iv_seed, &cc->key[key_offset], cc->iv_size);
	memcpy(tcw->whitening, &cc->key[key_offset + cc->iv_size],
	       TCW_WHITENING_SIZE);

	return 0;
}

static int crypt_iv_tcw_wipe(struct crypt_config *cc)
{
	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;

	memset(tcw->iv_seed, 0, cc->iv_size);
	memset(tcw->whitening, 0, TCW_WHITENING_SIZE);

	return 0;
}

static int crypt_iv_tcw_whitening(struct crypt_config *cc,
				  struct dm_crypt_request *dmreq,
				  u8 *data)
{
	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
	u64 sector = cpu_to_le64((u64)dmreq->iv_sector);
	u8 buf[TCW_WHITENING_SIZE];
	struct {
		struct shash_desc desc;
		char ctx[crypto_shash_descsize(tcw->crc32_tfm)];
	} sdesc;
	int i, r;

	/* xor whitening with sector number */
	memcpy(buf, tcw->whitening, TCW_WHITENING_SIZE);
	crypto_xor(buf, (u8 *)&sector, 8);
	crypto_xor(&buf[8], (u8 *)&sector, 8);

	/* calculate crc32 for every 32bit part and xor it */
	sdesc.desc.tfm = tcw->crc32_tfm;
	sdesc.desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
	for (i = 0; i < 4; i++) {
		r = crypto_shash_init(&sdesc.desc);
		if (r)
			goto out;
		r = crypto_shash_update(&sdesc.desc, &buf[i * 4], 4);
		if (r)
			goto out;
		r = crypto_shash_final(&sdesc.desc, &buf[i * 4]);
		if (r)
			goto out;
	}
	crypto_xor(&buf[0], &buf[12], 4);
	crypto_xor(&buf[4], &buf[8], 4);

	/* apply whitening (8 bytes) to whole sector */
	for (i = 0; i < ((1 << SECTOR_SHIFT) / 8); i++)
		crypto_xor(data + i * 8, buf, 8);
out:
	memset(buf, 0, sizeof(buf));
	return r;
}

static int crypt_iv_tcw_gen(struct crypt_config *cc, u8 *iv,
			    struct dm_crypt_request *dmreq)
{
	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
	u64 sector = cpu_to_le64((u64)dmreq->iv_sector);
	u8 *src;
	int r = 0;

	/* Remove whitening from ciphertext */
	if (bio_data_dir(dmreq->ctx->bio_in) != WRITE) {
		src = kmap_atomic(sg_page(&dmreq->sg_in));
		r = crypt_iv_tcw_whitening(cc, dmreq, src + dmreq->sg_in.offset);
		kunmap_atomic(src);
	}

	/* Calculate IV */
	memcpy(iv, tcw->iv_seed, cc->iv_size);
	crypto_xor(iv, (u8 *)&sector, 8);
	if (cc->iv_size > 8)
		crypto_xor(&iv[8], (u8 *)&sector, cc->iv_size - 8);

	return r;
}

static int crypt_iv_tcw_post(struct crypt_config *cc, u8 *iv,
			     struct dm_crypt_request *dmreq)
{
	u8 *dst;
	int r;

	if (bio_data_dir(dmreq->ctx->bio_in) != WRITE)
		return 0;

	/* Apply whitening on ciphertext */
	dst = kmap_atomic(sg_page(&dmreq->sg_out));
	r = crypt_iv_tcw_whitening(cc, dmreq, dst + dmreq->sg_out.offset);
	kunmap_atomic(dst);

	return r;
}

static struct crypt_iv_operations crypt_iv_plain_ops = {
	.generator = crypt_iv_plain_gen
};

static struct crypt_iv_operations crypt_iv_plain64_ops = {
	.generator = crypt_iv_plain64_gen
};

static struct crypt_iv_operations crypt_iv_essiv_ops = {
	.ctr       = crypt_iv_essiv_ctr,
	.dtr       = crypt_iv_essiv_dtr,
	.init      = crypt_iv_essiv_init,
	.wipe      = crypt_iv_essiv_wipe,
	.generator = crypt_iv_essiv_gen
};

static struct crypt_iv_operations crypt_iv_benbi_ops = {
	.ctr	   = crypt_iv_benbi_ctr,
	.dtr	   = crypt_iv_benbi_dtr,
	.generator = crypt_iv_benbi_gen
};

static struct crypt_iv_operations crypt_iv_null_ops = {
	.generator = crypt_iv_null_gen
};

static struct crypt_iv_operations crypt_iv_lmk_ops = {
	.ctr	   = crypt_iv_lmk_ctr,
	.dtr	   = crypt_iv_lmk_dtr,
	.init	   = crypt_iv_lmk_init,
	.wipe	   = crypt_iv_lmk_wipe,
	.generator = crypt_iv_lmk_gen,
	.post	   = crypt_iv_lmk_post
};

static struct crypt_iv_operations crypt_iv_tcw_ops = {
	.ctr	   = crypt_iv_tcw_ctr,
	.dtr	   = crypt_iv_tcw_dtr,
	.init	   = crypt_iv_tcw_init,
	.wipe	   = crypt_iv_tcw_wipe,
	.generator = crypt_iv_tcw_gen,
	.post	   = crypt_iv_tcw_post
};

static void crypt_convert_init(struct crypt_config *cc,
			       struct convert_context *ctx,
			       struct bio *bio_out, struct bio *bio_in,
			       sector_t sector)
{
	ctx->bio_in = bio_in;
	ctx->bio_out = bio_out;
	ctx->offset_in = 0;
	ctx->offset_out = 0;
	ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
	ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
	ctx->cc_sector = sector + cc->iv_offset;
	init_completion(&ctx->restart);
}

static struct dm_crypt_request *dmreq_of_req(struct crypt_config *cc,
					     struct ablkcipher_request *req)
{
	return (struct dm_crypt_request *)((char *)req + cc->dmreq_start);
}

static struct ablkcipher_request *req_of_dmreq(struct crypt_config *cc,
					       struct dm_crypt_request *dmreq)
{
	return (struct ablkcipher_request *)((char *)dmreq - cc->dmreq_start);
}

static u8 *iv_of_dmreq(struct crypt_config *cc,
		       struct dm_crypt_request *dmreq)
{
	return (u8 *)ALIGN((unsigned long)(dmreq + 1),
		crypto_ablkcipher_alignmask(any_tfm(cc)) + 1);
}

static int crypt_convert_block(struct crypt_config *cc,
			       struct convert_context *ctx,
			       struct ablkcipher_request *req)
{
	struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
	struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
	struct dm_crypt_request *dmreq;
	u8 *iv;
	int r;

	dmreq = dmreq_of_req(cc, req);
	iv = iv_of_dmreq(cc, dmreq);

	dmreq->iv_sector = ctx->cc_sector;
	dmreq->ctx = ctx;
	sg_init_table(&dmreq->sg_in, 1);
	sg_set_page(&dmreq->sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT,
		    bv_in->bv_offset + ctx->offset_in);

	sg_init_table(&dmreq->sg_out, 1);
	sg_set_page(&dmreq->sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT,
		    bv_out->bv_offset + ctx->offset_out);

	ctx->offset_in += 1 << SECTOR_SHIFT;
	if (ctx->offset_in >= bv_in->bv_len) {
		ctx->offset_in = 0;
		ctx->idx_in++;
	}

	ctx->offset_out += 1 << SECTOR_SHIFT;
	if (ctx->offset_out >= bv_out->bv_len) {
		ctx->offset_out = 0;
		ctx->idx_out++;
	}

	if (cc->iv_gen_ops) {
		r = cc->iv_gen_ops->generator(cc, iv, dmreq);
		if (r < 0)
			return r;
	}

	ablkcipher_request_set_crypt(req, &dmreq->sg_in, &dmreq->sg_out,
				     1 << SECTOR_SHIFT, iv);

	if (bio_data_dir(ctx->bio_in) == WRITE)
		r = crypto_ablkcipher_encrypt(req);
	else
		r = crypto_ablkcipher_decrypt(req);

	if (!r && cc->iv_gen_ops && cc->iv_gen_ops->post)
		r = cc->iv_gen_ops->post(cc, iv, dmreq);

	return r;
}

static void kcryptd_async_done(struct crypto_async_request *async_req,
			       int error);

static void crypt_alloc_req(struct crypt_config *cc,
			    struct convert_context *ctx)
{
	struct crypt_cpu *this_cc = this_crypt_config(cc);
	unsigned key_index = ctx->cc_sector & (cc->tfms_count - 1);

	if (!this_cc->req)
		this_cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);

	ablkcipher_request_set_tfm(this_cc->req, cc->tfms[key_index]);
	ablkcipher_request_set_callback(this_cc->req,
	    CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
	    kcryptd_async_done, dmreq_of_req(cc, this_cc->req));
}

/*
 * Encrypt / decrypt data from one bio to another one (can be the same one)
 */
static int crypt_convert(struct crypt_config *cc,
			 struct convert_context *ctx)
{
	struct crypt_cpu *this_cc = this_crypt_config(cc);
	int r;

	atomic_set(&ctx->cc_pending, 1);

	while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
	      ctx->idx_out < ctx->bio_out->bi_vcnt) {

		crypt_alloc_req(cc, ctx);

		atomic_inc(&ctx->cc_pending);

		r = crypt_convert_block(cc, ctx, this_cc->req);

		switch (r) {
		/* async */
		case -EBUSY:
			wait_for_completion(&ctx->restart);
			reinit_completion(&ctx->restart);
			/* fall through*/
		case -EINPROGRESS:
			this_cc->req = NULL;
			ctx->cc_sector++;
			continue;

		/* sync */
		case 0:
			atomic_dec(&ctx->cc_pending);
			ctx->cc_sector++;
			cond_resched();
			continue;

		/* error */
		default:
			atomic_dec(&ctx->cc_pending);
			return r;
		}
	}

	return 0;
}

/*
 * Generate a new unfragmented bio with the given size
 * This should never violate the device limitations
 * May return a smaller bio when running out of pages, indicated by
 * *out_of_pages set to 1.
 */
static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size,
				      unsigned *out_of_pages)
{
	struct crypt_config *cc = io->cc;
	struct bio *clone;
	unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
	gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
	unsigned i, len;
	struct page *page;

	clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
	if (!clone)
		return NULL;

	clone_init(io, clone);
	*out_of_pages = 0;

	for (i = 0; i < nr_iovecs; i++) {
		page = mempool_alloc(cc->page_pool, gfp_mask);
		if (!page) {
			*out_of_pages = 1;
			break;
		}

		/*
		 * If additional pages cannot be allocated without waiting,
		 * return a partially-allocated bio.  The caller will then try
		 * to allocate more bios while submitting this partial bio.
		 */
		gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;

		len = (size > PAGE_SIZE) ? PAGE_SIZE : size;

		if (!bio_add_page(clone, page, len, 0)) {
			mempool_free(page, cc->page_pool);
			break;
		}

		size -= len;
	}

	if (!clone->bi_size) {
		bio_put(clone);
		return NULL;
	}

	return clone;
}

static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
{
	unsigned int i;
	struct bio_vec *bv;

	bio_for_each_segment_all(bv, clone, i) {
		BUG_ON(!bv->bv_page);
		mempool_free(bv->bv_page, cc->page_pool);
		bv->bv_page = NULL;
	}
}

static struct dm_crypt_io *crypt_io_alloc(struct crypt_config *cc,
					  struct bio *bio, sector_t sector)
{
	struct dm_crypt_io *io;

	io = mempool_alloc(cc->io_pool, GFP_NOIO);
	io->cc = cc;
	io->base_bio = bio;
	io->sector = sector;
	io->error = 0;
	io->base_io = NULL;
	atomic_set(&io->io_pending, 0);

	return io;
}

static void crypt_inc_pending(struct dm_crypt_io *io)
{
	atomic_inc(&io->io_pending);
}

/*
 * One of the bios was finished. Check for completion of
 * the whole request and correctly clean up the buffer.
 * If base_io is set, wait for the last fragment to complete.
 */
static void crypt_dec_pending(struct dm_crypt_io *io)
{
	struct crypt_config *cc = io->cc;
	struct bio *base_bio = io->base_bio;
	struct dm_crypt_io *base_io = io->base_io;
	int error = io->error;

	if (!atomic_dec_and_test(&io->io_pending))
		return;

	mempool_free(io, cc->io_pool);

	if (likely(!base_io))
		bio_endio(base_bio, error);
	else {
		if (error && !base_io->error)
			base_io->error = error;
		crypt_dec_pending(base_io);
	}
}

/*
 * kcryptd/kcryptd_io:
 *
 * Needed because it would be very unwise to do decryption in an
 * interrupt context.
 *
 * kcryptd performs the actual encryption or decryption.
 *
 * kcryptd_io performs the IO submission.
 *
 * They must be separated as otherwise the final stages could be
 * starved by new requests which can block in the first stages due
 * to memory allocation.
 *
 * The work is done per CPU global for all dm-crypt instances.
 * They should not depend on each other and do not block.
 */
static void crypt_endio(struct bio *clone, int error)
{
	struct dm_crypt_io *io = clone->bi_private;
	struct crypt_config *cc = io->cc;
	unsigned rw = bio_data_dir(clone);

	if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
		error = -EIO;

	/*
	 * free the processed pages
	 */
	if (rw == WRITE)
		crypt_free_buffer_pages(cc, clone);

	bio_put(clone);

	if (rw == READ && !error) {
		kcryptd_queue_crypt(io);
		return;
	}

	if (unlikely(error))
		io->error = error;

	crypt_dec_pending(io);
}

static void clone_init(struct dm_crypt_io *io, struct bio *clone)
{
	struct crypt_config *cc = io->cc;

	clone->bi_private = io;
	clone->bi_end_io  = crypt_endio;
	clone->bi_bdev    = cc->dev->bdev;
	clone->bi_rw      = io->base_bio->bi_rw;
}

static int kcryptd_io_read(struct dm_crypt_io *io, gfp_t gfp)
{
	struct crypt_config *cc = io->cc;
	struct bio *base_bio = io->base_bio;
	struct bio *clone;

	/*
	 * The block layer might modify the bvec array, so always
	 * copy the required bvecs because we need the original
	 * one in order to decrypt the whole bio data *afterwards*.
	 */
	clone = bio_clone_bioset(base_bio, gfp, cc->bs);
	if (!clone)
		return 1;

	crypt_inc_pending(io);

	clone_init(io, clone);
	clone->bi_sector = cc->start + io->sector;

	generic_make_request(clone);
	return 0;
}

static void kcryptd_io_write(struct dm_crypt_io *io)
{
	struct bio *clone = io->ctx.bio_out;
	generic_make_request(clone);
}

static void kcryptd_io(struct work_struct *work)
{
	struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);

	if (bio_data_dir(io->base_bio) == READ) {
		crypt_inc_pending(io);
		if (kcryptd_io_read(io, GFP_NOIO))
			io->error = -ENOMEM;
		crypt_dec_pending(io);
	} else
		kcryptd_io_write(io);
}

static void kcryptd_queue_io(struct dm_crypt_io *io)
{
	struct crypt_config *cc = io->cc;

	INIT_WORK(&io->work, kcryptd_io);
	queue_work(cc->io_queue, &io->work);
}

static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int async)
{
	struct bio *clone = io->ctx.bio_out;
	struct crypt_config *cc = io->cc;

	if (unlikely(io->error < 0)) {
		crypt_free_buffer_pages(cc, clone);
		bio_put(clone);
		crypt_dec_pending(io);
		return;
	}

	/* crypt_convert should have filled the clone bio */
	BUG_ON(io->ctx.idx_out < clone->bi_vcnt);

	clone->bi_sector = cc->start + io->sector;

	if (async)
		kcryptd_queue_io(io);
	else
		generic_make_request(clone);
}

static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
{
	struct crypt_config *cc = io->cc;
	struct bio *clone;
	struct dm_crypt_io *new_io;
	int crypt_finished;
	unsigned out_of_pages = 0;
	unsigned remaining = io->base_bio->bi_size;
	sector_t sector = io->sector;
	int r;

	/*
	 * Prevent io from disappearing until this function completes.
	 */
	crypt_inc_pending(io);
	crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector);

	/*
	 * The allocated buffers can be smaller than the whole bio,
	 * so repeat the whole process until all the data can be handled.
	 */
	while (remaining) {
		clone = crypt_alloc_buffer(io, remaining, &out_of_pages);
		if (unlikely(!clone)) {
			io->error = -ENOMEM;
			break;
		}

		io->ctx.bio_out = clone;
		io->ctx.idx_out = 0;

		remaining -= clone->bi_size;
		sector += bio_sectors(clone);

		crypt_inc_pending(io);

		r = crypt_convert(cc, &io->ctx);
		if (r < 0)
			io->error = -EIO;

		crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending);

		/* Encryption was already finished, submit io now */
		if (crypt_finished) {
			kcryptd_crypt_write_io_submit(io, 0);

			/*
			 * If there was an error, do not try next fragments.
			 * For async, error is processed in async handler.
			 */
			if (unlikely(r < 0))
				break;

			io->sector = sector;
		}

		/*
		 * Out of memory -> run queues
		 * But don't wait if split was due to the io size restriction
		 */
		if (unlikely(out_of_pages))
			congestion_wait(BLK_RW_ASYNC, HZ/100);

		/*
		 * With async crypto it is unsafe to share the crypto context
		 * between fragments, so switch to a new dm_crypt_io structure.
		 */
		if (unlikely(!crypt_finished && remaining)) {
			new_io = crypt_io_alloc(io->cc, io->base_bio,
						sector);
			crypt_inc_pending(new_io);
			crypt_convert_init(cc, &new_io->ctx, NULL,
					   io->base_bio, sector);
			new_io->ctx.idx_in = io->ctx.idx_in;
			new_io->ctx.offset_in = io->ctx.offset_in;

			/*
			 * Fragments after the first use the base_io
			 * pending count.
			 */
			if (!io->base_io)
				new_io->base_io = io;
			else {
				new_io->base_io = io->base_io;
				crypt_inc_pending(io->base_io);
				crypt_dec_pending(io);
			}

			io = new_io;
		}
	}

	crypt_dec_pending(io);
}

static void kcryptd_crypt_read_done(struct dm_crypt_io *io)
{
	crypt_dec_pending(io);
}

static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)
{
	struct crypt_config *cc = io->cc;
	int r = 0;

	crypt_inc_pending(io);

	crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,
			   io->sector);

	r = crypt_convert(cc, &io->ctx);
	if (r < 0)
		io->error = -EIO;

	if (atomic_dec_and_test(&io->ctx.cc_pending))
		kcryptd_crypt_read_done(io);

	crypt_dec_pending(io);
}

static void kcryptd_async_done(struct crypto_async_request *async_req,
			       int error)
{
	struct dm_crypt_request *dmreq = async_req->data;
	struct convert_context *ctx = dmreq->ctx;
	struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
	struct crypt_config *cc = io->cc;

	if (error == -EINPROGRESS) {
		complete(&ctx->restart);
		return;
	}

	if (!error && cc->iv_gen_ops && cc->iv_gen_ops->post)
		error = cc->iv_gen_ops->post(cc, iv_of_dmreq(cc, dmreq), dmreq);

	if (error < 0)
		io->error = -EIO;

	mempool_free(req_of_dmreq(cc, dmreq), cc->req_pool);

	if (!atomic_dec_and_test(&ctx->cc_pending))
		return;

	if (bio_data_dir(io->base_bio) == READ)
		kcryptd_crypt_read_done(io);
	else
		kcryptd_crypt_write_io_submit(io, 1);
}

static void kcryptd_crypt(struct work_struct *work)
{
	struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);

	if (bio_data_dir(io->base_bio) == READ)
		kcryptd_crypt_read_convert(io);
	else
		kcryptd_crypt_write_convert(io);
}

static void kcryptd_queue_crypt(struct dm_crypt_io *io)
{
	struct crypt_config *cc = io->cc;

	INIT_WORK(&io->work, kcryptd_crypt);
	queue_work(cc->crypt_queue, &io->work);
}

/*
 * Decode key from its hex representation
 */
static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
{
	char buffer[3];
	unsigned int i;

	buffer[2] = '\0';

	for (i = 0; i < size; i++) {
		buffer[0] = *hex++;
		buffer[1] = *hex++;

		if (kstrtou8(buffer, 16, &key[i]))
			return -EINVAL;
	}

	if (*hex != '\0')
		return -EINVAL;

	return 0;
}

static void crypt_free_tfms(struct crypt_config *cc)
{
	unsigned i;

	if (!cc->tfms)
		return;

	for (i = 0; i < cc->tfms_count; i++)
		if (cc->tfms[i] && !IS_ERR(cc->tfms[i])) {
			crypto_free_ablkcipher(cc->tfms[i]);
			cc->tfms[i] = NULL;
		}

	kfree(cc->tfms);
	cc->tfms = NULL;
}

static int crypt_alloc_tfms(struct crypt_config *cc, char *ciphermode)
{
	unsigned i;
	int err;

	cc->tfms = kmalloc(cc->tfms_count * sizeof(struct crypto_ablkcipher *),
			   GFP_KERNEL);
	if (!cc->tfms)
		return -ENOMEM;

	for (i = 0; i < cc->tfms_count; i++) {
		cc->tfms[i] = crypto_alloc_ablkcipher(ciphermode, 0, 0);
		if (IS_ERR(cc->tfms[i])) {
			err = PTR_ERR(cc->tfms[i]);
			crypt_free_tfms(cc);
			return err;
		}
	}

	return 0;
}

static int crypt_setkey_allcpus(struct crypt_config *cc)
{
	unsigned subkey_size;
	int err = 0, i, r;

	/* Ignore extra keys (which are used for IV etc) */
	subkey_size = (cc->key_size - cc->key_extra_size) >> ilog2(cc->tfms_count);

	for (i = 0; i < cc->tfms_count; i++) {
		r = crypto_ablkcipher_setkey(cc->tfms[i],
					     cc->key + (i * subkey_size),
					     subkey_size);
		if (r)
			err = r;
	}

	return err;
}

static int crypt_set_key(struct crypt_config *cc, char *key)
{
	int r = -EINVAL;
	int key_string_len = strlen(key);

	/* The key size may not be changed. */
	if (cc->key_size != (key_string_len >> 1))
		goto out;

	/* Hyphen (which gives a key_size of zero) means there is no key. */
	if (!cc->key_size && strcmp(key, "-"))
		goto out;

	if (cc->key_size && crypt_decode_key(cc->key, key, cc->key_size) < 0)
		goto out;

	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);

	r = crypt_setkey_allcpus(cc);

out:
	/* Hex key string not needed after here, so wipe it. */
	memset(key, '0', key_string_len);

	return r;
}

static int crypt_wipe_key(struct crypt_config *cc)
{
	clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
	memset(&cc->key, 0, cc->key_size * sizeof(u8));

	return crypt_setkey_allcpus(cc);
}

static void crypt_dtr(struct dm_target *ti)
{
	struct crypt_config *cc = ti->private;
	struct crypt_cpu *cpu_cc;
	int cpu;

	ti->private = NULL;

	if (!cc)
		return;

	if (cc->io_queue)
		destroy_workqueue(cc->io_queue);
	if (cc->crypt_queue)
		destroy_workqueue(cc->crypt_queue);

	if (cc->cpu)
		for_each_possible_cpu(cpu) {
			cpu_cc = per_cpu_ptr(cc->cpu, cpu);
			if (cpu_cc->req)
				mempool_free(cpu_cc->req, cc->req_pool);
		}

	crypt_free_tfms(cc);

	if (cc->bs)
		bioset_free(cc->bs);

	if (cc->page_pool)
		mempool_destroy(cc->page_pool);
	if (cc->req_pool)
		mempool_destroy(cc->req_pool);
	if (cc->io_pool)
		mempool_destroy(cc->io_pool);

	if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
		cc->iv_gen_ops->dtr(cc);

	if (cc->dev)
		dm_put_device(ti, cc->dev);

	if (cc->cpu)
		free_percpu(cc->cpu);

	kzfree(cc->cipher);
	kzfree(cc->cipher_string);

	/* Must zero key material before freeing */
	kzfree(cc);
}

static int crypt_ctr_cipher(struct dm_target *ti,
			    char *cipher_in, char *key)
{
	struct crypt_config *cc = ti->private;
	char *tmp, *cipher, *chainmode, *ivmode, *ivopts, *keycount;
	char *cipher_api = NULL;
	int ret = -EINVAL;
	char dummy;

	/* Convert to crypto api definition? */
	if (strchr(cipher_in, '(')) {
		ti->error = "Bad cipher specification";
		return -EINVAL;
	}

	cc->cipher_string = kstrdup(cipher_in, GFP_KERNEL);
	if (!cc->cipher_string)
		goto bad_mem;

	/*
	 * Legacy dm-crypt cipher specification
	 * cipher[:keycount]-mode-iv:ivopts
	 */
	tmp = cipher_in;
	keycount = strsep(&tmp, "-");
	cipher = strsep(&keycount, ":");

	if (!keycount)
		cc->tfms_count = 1;
	else if (sscanf(keycount, "%u%c", &cc->tfms_count, &dummy) != 1 ||
		 !is_power_of_2(cc->tfms_count)) {
		ti->error = "Bad cipher key count specification";
		return -EINVAL;
	}
	cc->key_parts = cc->tfms_count;
	cc->key_extra_size = 0;

	cc->cipher = kstrdup(cipher, GFP_KERNEL);
	if (!cc->cipher)
		goto bad_mem;

	chainmode = strsep(&tmp, "-");
	ivopts = strsep(&tmp, "-");
	ivmode = strsep(&ivopts, ":");

	if (tmp)
		DMWARN("Ignoring unexpected additional cipher options");

	cc->cpu = __alloc_percpu(sizeof(*(cc->cpu)),
				 __alignof__(struct crypt_cpu));
	if (!cc->cpu) {
		ti->error = "Cannot allocate per cpu state";
		goto bad_mem;
	}

	/*
	 * For compatibility with the original dm-crypt mapping format, if
	 * only the cipher name is supplied, use cbc-plain.
	 */
	if (!chainmode || (!strcmp(chainmode, "plain") && !ivmode)) {
		chainmode = "cbc";
		ivmode = "plain";
	}

	if (strcmp(chainmode, "ecb") && !ivmode) {
		ti->error = "IV mechanism required";
		return -EINVAL;
	}

	cipher_api = kmalloc(CRYPTO_MAX_ALG_NAME, GFP_KERNEL);
	if (!cipher_api)
		goto bad_mem;

	ret = snprintf(cipher_api, CRYPTO_MAX_ALG_NAME,
		       "%s(%s)", chainmode, cipher);
	if (ret < 0) {
		kfree(cipher_api);
		goto bad_mem;
	}

	/* Allocate cipher */
	ret = crypt_alloc_tfms(cc, cipher_api);
	if (ret < 0) {
		ti->error = "Error allocating crypto tfm";
		goto bad;
	}

	/* Initialize IV */
	cc->iv_size = crypto_ablkcipher_ivsize(any_tfm(cc));
	if (cc->iv_size)
		/* at least a 64 bit sector number should fit in our buffer */
		cc->iv_size = max(cc->iv_size,
				  (unsigned int)(sizeof(u64) / sizeof(u8)));
	else if (ivmode) {
		DMWARN("Selected cipher does not support IVs");
		ivmode = NULL;
	}

	/* Choose ivmode, see comments at iv code. */
	if (ivmode == NULL)
		cc->iv_gen_ops = NULL;
	else if (strcmp(ivmode, "plain") == 0)
		cc->iv_gen_ops = &crypt_iv_plain_ops;
	else if (strcmp(ivmode, "plain64") == 0)
		cc->iv_gen_ops = &crypt_iv_plain64_ops;
	else if (strcmp(ivmode, "essiv") == 0)
		cc->iv_gen_ops = &crypt_iv_essiv_ops;
	else if (strcmp(ivmode, "benbi") == 0)
		cc->iv_gen_ops = &crypt_iv_benbi_ops;
	else if (strcmp(ivmode, "null") == 0)
		cc->iv_gen_ops = &crypt_iv_null_ops;
	else if (strcmp(ivmode, "lmk") == 0) {
		cc->iv_gen_ops = &crypt_iv_lmk_ops;
		/*
		 * Version 2 and 3 is recognised according
		 * to length of provided multi-key string.
		 * If present (version 3), last key is used as IV seed.
		 * All keys (including IV seed) are always the same size.
		 */
		if (cc->key_size % cc->key_parts) {
			cc->key_parts++;
			cc->key_extra_size = cc->key_size / cc->key_parts;
		}
	} else if (strcmp(ivmode, "tcw") == 0) {
		cc->iv_gen_ops = &crypt_iv_tcw_ops;
		cc->key_parts += 2; /* IV + whitening */
		cc->key_extra_size = cc->iv_size + TCW_WHITENING_SIZE;
	} else {
		ret = -EINVAL;
		ti->error = "Invalid IV mode";
		goto bad;
	}

	/* Initialize and set key */
	ret = crypt_set_key(cc, key);
	if (ret < 0) {
		ti->error = "Error decoding and setting key";
		goto bad;
	}

	/* Allocate IV */
	if (cc->iv_gen_ops && cc->iv_gen_ops->ctr) {
		ret = cc->iv_gen_ops->ctr(cc, ti, ivopts);
		if (ret < 0) {
			ti->error = "Error creating IV";
			goto bad;
		}
	}

	/* Initialize IV (set keys for ESSIV etc) */
	if (cc->iv_gen_ops && cc->iv_gen_ops->init) {
		ret = cc->iv_gen_ops->init(cc);
		if (ret < 0) {
			ti->error = "Error initialising IV";
			goto bad;
		}
	}

	ret = 0;
bad:
	kfree(cipher_api);
	return ret;

bad_mem:
	ti->error = "Cannot allocate cipher strings";
	return -ENOMEM;
}

/*
 * Construct an encryption mapping:
 * <cipher> <key> <iv_offset> <dev_path> <start>
 */
static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
	struct crypt_config *cc;
	unsigned int key_size, opt_params;
	unsigned long long tmpll;
	int ret;
	struct dm_arg_set as;
	const char *opt_string;
	char dummy;

	static struct dm_arg _args[] = {
		{0, 1, "Invalid number of feature args"},
	};

	if (argc < 5) {
		ti->error = "Not enough arguments";
		return -EINVAL;
	}

	key_size = strlen(argv[1]) >> 1;

	cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
	if (!cc) {
		ti->error = "Cannot allocate encryption context";
		return -ENOMEM;
	}
	cc->key_size = key_size;

	ti->private = cc;
	ret = crypt_ctr_cipher(ti, argv[0], argv[1]);
	if (ret < 0)
		goto bad;

	ret = -ENOMEM;
	cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
	if (!cc->io_pool) {
		ti->error = "Cannot allocate crypt io mempool";
		goto bad;
	}

	cc->dmreq_start = sizeof(struct ablkcipher_request);
	cc->dmreq_start += crypto_ablkcipher_reqsize(any_tfm(cc));
	cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment());
	cc->dmreq_start += crypto_ablkcipher_alignmask(any_tfm(cc)) &
			   ~(crypto_tfm_ctx_alignment() - 1);

	cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
			sizeof(struct dm_crypt_request) + cc->iv_size);
	if (!cc->req_pool) {
		ti->error = "Cannot allocate crypt request mempool";
		goto bad;
	}

	cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
	if (!cc->page_pool) {
		ti->error = "Cannot allocate page mempool";
		goto bad;
	}

	cc->bs = bioset_create(MIN_IOS, 0);
	if (!cc->bs) {
		ti->error = "Cannot allocate crypt bioset";
		goto bad;
	}

	ret = -EINVAL;
	if (sscanf(argv[2], "%llu%c", &tmpll, &dummy) != 1) {
		ti->error = "Invalid iv_offset sector";
		goto bad;
	}
	cc->iv_offset = tmpll;

	if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &cc->dev)) {
		ti->error = "Device lookup failed";
		goto bad;
	}

	if (sscanf(argv[4], "%llu%c", &tmpll, &dummy) != 1) {
		ti->error = "Invalid device sector";
		goto bad;
	}
	cc->start = tmpll;

	argv += 5;
	argc -= 5;

	/* Optional parameters */
	if (argc) {
		as.argc = argc;
		as.argv = argv;

		ret = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
		if (ret)
			goto bad;

		opt_string = dm_shift_arg(&as);

		if (opt_params == 1 && opt_string &&
		    !strcasecmp(opt_string, "allow_discards"))
			ti->num_discard_bios = 1;
		else if (opt_params) {
			ret = -EINVAL;
			ti->error = "Invalid feature arguments";
			goto bad;
		}
	}

	ret = -ENOMEM;
	cc->io_queue = alloc_workqueue("kcryptd_io", WQ_MEM_RECLAIM, 1);
	if (!cc->io_queue) {
		ti->error = "Couldn't create kcryptd io queue";
		goto bad;
	}

	cc->crypt_queue = alloc_workqueue("kcryptd",
					  WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM, 1);
	if (!cc->crypt_queue) {
		ti->error = "Couldn't create kcryptd queue";
		goto bad;
	}

	ti->num_flush_bios = 1;
	ti->discard_zeroes_data_unsupported = true;

	return 0;

bad:
	crypt_dtr(ti);
	return ret;
}

static int crypt_map(struct dm_target *ti, struct bio *bio)
{
	struct dm_crypt_io *io;
	struct crypt_config *cc = ti->private;

	/*
	 * If bio is REQ_FLUSH or REQ_DISCARD, just bypass crypt queues.
	 * - for REQ_FLUSH device-mapper core ensures that no IO is in-flight
	 * - for REQ_DISCARD caller must use flush if IO ordering matters
	 */
	if (unlikely(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD))) {
		bio->bi_bdev = cc->dev->bdev;
		if (bio_sectors(bio))
			bio->bi_sector = cc->start + dm_target_offset(ti, bio->bi_sector);
		return DM_MAPIO_REMAPPED;
	}

	io = crypt_io_alloc(cc, bio, dm_target_offset(ti, bio->bi_sector));

	if (bio_data_dir(io->base_bio) == READ) {
		if (kcryptd_io_read(io, GFP_NOWAIT))
			kcryptd_queue_io(io);
	} else
		kcryptd_queue_crypt(io);

	return DM_MAPIO_SUBMITTED;
}

static void crypt_status(struct dm_target *ti, status_type_t type,
			 unsigned status_flags, char *result, unsigned maxlen)
{
	struct crypt_config *cc = ti->private;
	unsigned i, sz = 0;

	switch (type) {
	case STATUSTYPE_INFO:
		result[0] = '\0';
		break;

	case STATUSTYPE_TABLE:
		DMEMIT("%s ", cc->cipher_string);

		if (cc->key_size > 0)
			for (i = 0; i < cc->key_size; i++)
				DMEMIT("%02x", cc->key[i]);
		else
			DMEMIT("-");

		DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
				cc->dev->name, (unsigned long long)cc->start);

		if (ti->num_discard_bios)
			DMEMIT(" 1 allow_discards");

		break;
	}
}

static void crypt_postsuspend(struct dm_target *ti)
{
	struct crypt_config *cc = ti->private;

	set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
}

static int crypt_preresume(struct dm_target *ti)
{
	struct crypt_config *cc = ti->private;

	if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
		DMERR("aborting resume - crypt key is not set.");
		return -EAGAIN;
	}

	return 0;
}

static void crypt_resume(struct dm_target *ti)
{
	struct crypt_config *cc = ti->private;

	clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
}

/* Message interface
 *	key set <key>
 *	key wipe
 */
static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
{
	struct crypt_config *cc = ti->private;
	int ret = -EINVAL;

	if (argc < 2)
		goto error;

	if (!strcasecmp(argv[0], "key")) {
		if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
			DMWARN("not suspended during key manipulation.");
			return -EINVAL;
		}
		if (argc == 3 && !strcasecmp(argv[1], "set")) {
			ret = crypt_set_key(cc, argv[2]);
			if (ret)
				return ret;
			if (cc->iv_gen_ops && cc->iv_gen_ops->init)
				ret = cc->iv_gen_ops->init(cc);
			return ret;
		}
		if (argc == 2 && !strcasecmp(argv[1], "wipe")) {
			if (cc->iv_gen_ops && cc->iv_gen_ops->wipe) {
				ret = cc->iv_gen_ops->wipe(cc);
				if (ret)
					return ret;
			}
			return crypt_wipe_key(cc);
		}
	}

error:
	DMWARN("unrecognised message received.");
	return -EINVAL;
}

static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
		       struct bio_vec *biovec, int max_size)
{
	struct crypt_config *cc = ti->private;
	struct request_queue *q = bdev_get_queue(cc->dev->bdev);

	if (!q->merge_bvec_fn)
		return max_size;

	bvm->bi_bdev = cc->dev->bdev;
	bvm->bi_sector = cc->start + dm_target_offset(ti, bvm->bi_sector);

	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
}

static int crypt_iterate_devices(struct dm_target *ti,
				 iterate_devices_callout_fn fn, void *data)
{
	struct crypt_config *cc = ti->private;

	return fn(ti, cc->dev, cc->start, ti->len, data);
}

static struct target_type crypt_target = {
	.name   = "crypt",
	.version = {1, 13, 0},
	.module = THIS_MODULE,
	.ctr    = crypt_ctr,
	.dtr    = crypt_dtr,
	.map    = crypt_map,
	.status = crypt_status,
	.postsuspend = crypt_postsuspend,
	.preresume = crypt_preresume,
	.resume = crypt_resume,
	.message = crypt_message,
	.merge  = crypt_merge,
	.iterate_devices = crypt_iterate_devices,
};

static int __init dm_crypt_init(void)
{
	int r;

	_crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
	if (!_crypt_io_pool)
		return -ENOMEM;

	r = dm_register_target(&crypt_target);
	if (r < 0) {
		DMERR("register failed %d", r);
		kmem_cache_destroy(_crypt_io_pool);
	}

	return r;
}

static void __exit dm_crypt_exit(void)
{
	dm_unregister_target(&crypt_target);
	kmem_cache_destroy(_crypt_io_pool);
}

module_init(dm_crypt_init);
module_exit(dm_crypt_exit);

MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
MODULE_LICENSE("GPL");