aboutsummaryrefslogtreecommitdiff
path: root/drivers/md/dm-crypt.c
blob: cf6631056683b76cc3abbf2afa0a9564261de5f5 (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
/*
 * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
 * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
 *
 * This file is released under the GPL.
 */

#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 <asm/atomic.h>
#include <linux/scatterlist.h>
#include <asm/page.h>

#include "dm.h"

#define PFX	"crypt: "

/*
 * per bio private data
 */
struct crypt_io {
	struct dm_target *target;
	struct bio *bio;
	struct bio *first_clone;
	struct work_struct work;
	atomic_t pending;
	int error;
};

/*
 * context holding the current state of a multi-part conversion
 */
struct convert_context {
	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 sector;
	int write;
};

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);
	const char *(*status)(struct crypt_config *cc);
	int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
};

/*
 * Crypt: maps a linear range of a block device
 * and encrypts / decrypts at the same time.
 */
struct crypt_config {
	struct dm_dev *dev;
	sector_t start;

	/*
	 * pool for per bio private data and
	 * for encryption buffer pages
	 */
	mempool_t *io_pool;
	mempool_t *page_pool;

	/*
	 * crypto related data
	 */
	struct crypt_iv_operations *iv_gen_ops;
	char *iv_mode;
	void *iv_gen_private;
	sector_t iv_offset;
	unsigned int iv_size;

	struct crypto_tfm *tfm;
	unsigned int key_size;
	u8 key[0];
};

#define MIN_IOS        256
#define MIN_POOL_PAGES 32
#define MIN_BIO_PAGES  8

static kmem_cache_t *_crypt_io_pool;

/*
 * Mempool alloc and free functions for the page
 */
static void *mempool_alloc_page(gfp_t gfp_mask, void *data)
{
	return alloc_page(gfp_mask);
}

static void mempool_free_page(void *page, void *data)
{
	__free_page(page);
}


/*
 * Different IV generation algorithms:
 *
 * plain: the initial vector is the 32-bit low-endian version of the sector
 *        number, padded with zeros if neccessary.
 *
 * ess_iv: "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.
 *
 * 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, sector_t sector)
{
	memset(iv, 0, cc->iv_size);
	*(u32 *)iv = cpu_to_le32(sector & 0xffffffff);

	return 0;
}

static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
	                      const char *opts)
{
	struct crypto_tfm *essiv_tfm;
	struct crypto_tfm *hash_tfm;
	struct scatterlist sg;
	unsigned int saltsize;
	u8 *salt;

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

	/* Hash the cipher key with the given hash algorithm */
	hash_tfm = crypto_alloc_tfm(opts, CRYPTO_TFM_REQ_MAY_SLEEP);
	if (hash_tfm == NULL) {
		ti->error = PFX "Error initializing ESSIV hash";
		return -EINVAL;
	}

	if (crypto_tfm_alg_type(hash_tfm) != CRYPTO_ALG_TYPE_DIGEST) {
		ti->error = PFX "Expected digest algorithm for ESSIV hash";
		crypto_free_tfm(hash_tfm);
		return -EINVAL;
	}

	saltsize = crypto_tfm_alg_digestsize(hash_tfm);
	salt = kmalloc(saltsize, GFP_KERNEL);
	if (salt == NULL) {
		ti->error = PFX "Error kmallocing salt storage in ESSIV";
		crypto_free_tfm(hash_tfm);
		return -ENOMEM;
	}

	sg_set_buf(&sg, cc->key, cc->key_size);
	crypto_digest_digest(hash_tfm, &sg, 1, salt);
	crypto_free_tfm(hash_tfm);

	/* Setup the essiv_tfm with the given salt */
	essiv_tfm = crypto_alloc_tfm(crypto_tfm_alg_name(cc->tfm),
	                             CRYPTO_TFM_MODE_ECB |
	                             CRYPTO_TFM_REQ_MAY_SLEEP);
	if (essiv_tfm == NULL) {
		ti->error = PFX "Error allocating crypto tfm for ESSIV";
		kfree(salt);
		return -EINVAL;
	}
	if (crypto_tfm_alg_blocksize(essiv_tfm)
	    != crypto_tfm_alg_ivsize(cc->tfm)) {
		ti->error = PFX "Block size of ESSIV cipher does "
			        "not match IV size of block cipher";
		crypto_free_tfm(essiv_tfm);
		kfree(salt);
		return -EINVAL;
	}
	if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) {
		ti->error = PFX "Failed to set key for ESSIV cipher";
		crypto_free_tfm(essiv_tfm);
		kfree(salt);
		return -EINVAL;
	}
	kfree(salt);

	cc->iv_gen_private = (void *)essiv_tfm;
	return 0;
}

static void crypt_iv_essiv_dtr(struct crypt_config *cc)
{
	crypto_free_tfm((struct crypto_tfm *)cc->iv_gen_private);
	cc->iv_gen_private = NULL;
}

static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
{
	struct scatterlist sg;

	memset(iv, 0, cc->iv_size);
	*(u64 *)iv = cpu_to_le64(sector);

	sg_set_buf(&sg, iv, cc->iv_size);
	crypto_cipher_encrypt((struct crypto_tfm *)cc->iv_gen_private,
	                      &sg, &sg, cc->iv_size);

	return 0;
}

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

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


static inline int
crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
                          struct scatterlist *in, unsigned int length,
                          int write, sector_t sector)
{
	u8 iv[cc->iv_size];
	int r;

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

		if (write)
			r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv);
		else
			r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv);
	} else {
		if (write)
			r = crypto_cipher_encrypt(cc->tfm, out, in, length);
		else
			r = crypto_cipher_decrypt(cc->tfm, out, in, length);
	}

	return r;
}

static void
crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
                   struct bio *bio_out, struct bio *bio_in,
                   sector_t sector, int write)
{
	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->sector = sector + cc->iv_offset;
	ctx->write = write;
}

/*
 * 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)
{
	int r = 0;

	while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
	      ctx->idx_out < ctx->bio_out->bi_vcnt) {
		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 scatterlist sg_in = {
			.page = bv_in->bv_page,
			.offset = bv_in->bv_offset + ctx->offset_in,
			.length = 1 << SECTOR_SHIFT
		};
		struct scatterlist sg_out = {
			.page = bv_out->bv_page,
			.offset = bv_out->bv_offset + ctx->offset_out,
			.length = 1 << SECTOR_SHIFT
		};

		ctx->offset_in += sg_in.length;
		if (ctx->offset_in >= bv_in->bv_len) {
			ctx->offset_in = 0;
			ctx->idx_in++;
		}

		ctx->offset_out += sg_out.length;
		if (ctx->offset_out >= bv_out->bv_len) {
			ctx->offset_out = 0;
			ctx->idx_out++;
		}

		r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
		                              ctx->write, ctx->sector);
		if (r < 0)
			break;

		ctx->sector++;
	}

	return r;
}

/*
 * 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
 */
static struct bio *
crypt_alloc_buffer(struct crypt_config *cc, unsigned int size,
                   struct bio *base_bio, unsigned int *bio_vec_idx)
{
	struct bio *bio;
	unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
	gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
	unsigned int i;

	/*
	 * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and
	 * to fail earlier.  This is not necessary but increases throughput.
	 * FIXME: Is this really intelligent?
	 */
	if (base_bio)
		bio = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC);
	else
		bio = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs);
	if (!bio)
		return NULL;

	/* if the last bio was not complete, continue where that one ended */
	bio->bi_idx = *bio_vec_idx;
	bio->bi_vcnt = *bio_vec_idx;
	bio->bi_size = 0;
	bio->bi_flags &= ~(1 << BIO_SEG_VALID);

	/* bio->bi_idx pages have already been allocated */
	size -= bio->bi_idx * PAGE_SIZE;

	for(i = bio->bi_idx; i < nr_iovecs; i++) {
		struct bio_vec *bv = bio_iovec_idx(bio, i);

		bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
		if (!bv->bv_page)
			break;

		/*
		 * if additional pages cannot be allocated without waiting,
		 * return a partially allocated bio, the caller will then try
		 * to allocate additional bios while submitting this partial bio
		 */
		if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1))
			gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;

		bv->bv_offset = 0;
		if (size > PAGE_SIZE)
			bv->bv_len = PAGE_SIZE;
		else
			bv->bv_len = size;

		bio->bi_size += bv->bv_len;
		bio->bi_vcnt++;
		size -= bv->bv_len;
	}

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

	/*
	 * Remember the last bio_vec allocated to be able
	 * to correctly continue after the splitting.
	 */
	*bio_vec_idx = bio->bi_vcnt;

	return bio;
}

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

	/*
	 * This is ugly, but Jens Axboe thinks that using bi_idx in the
	 * endio function is too dangerous at the moment, so I calculate the
	 * correct position using bi_vcnt and bi_size.
	 * The bv_offset and bv_len fields might already be modified but we
	 * know that we always allocated whole pages.
	 * A fix to the bi_idx issue in the kernel is in the works, so
	 * we will hopefully be able to revert to the cleaner solution soon.
	 */
	i = bio->bi_vcnt - 1;
	bv = bio_iovec_idx(bio, i);
	end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size;
	start = end - bytes;

	start >>= PAGE_SHIFT;
	if (!bio->bi_size)
		end = bio->bi_vcnt;
	else
		end >>= PAGE_SHIFT;

	for(i = start; i < end; i++) {
		bv = bio_iovec_idx(bio, i);
		BUG_ON(!bv->bv_page);
		mempool_free(bv->bv_page, cc->page_pool);
		bv->bv_page = NULL;
	}
}

/*
 * One of the bios was finished. Check for completion of
 * the whole request and correctly clean up the buffer.
 */
static void dec_pending(struct crypt_io *io, int error)
{
	struct crypt_config *cc = (struct crypt_config *) io->target->private;

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

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

	if (io->first_clone)
		bio_put(io->first_clone);

	bio_endio(io->bio, io->bio->bi_size, io->error);

	mempool_free(io, cc->io_pool);
}

/*
 * kcryptd:
 *
 * Needed because it would be very unwise to do decryption in an
 * interrupt context, so bios returning from read requests get
 * queued here.
 */
static struct workqueue_struct *_kcryptd_workqueue;

static void kcryptd_do_work(void *data)
{
	struct crypt_io *io = (struct crypt_io *) data;
	struct crypt_config *cc = (struct crypt_config *) io->target->private;
	struct convert_context ctx;
	int r;

	crypt_convert_init(cc, &ctx, io->bio, io->bio,
	                   io->bio->bi_sector - io->target->begin, 0);
	r = crypt_convert(cc, &ctx);

	dec_pending(io, r);
}

static void kcryptd_queue_io(struct crypt_io *io)
{
	INIT_WORK(&io->work, kcryptd_do_work, io);
	queue_work(_kcryptd_workqueue, &io->work);
}

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

	buffer[2] = '\0';

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

		key[i] = (u8)simple_strtoul(buffer, &endp, 16);

		if (endp != &buffer[2])
			return -EINVAL;
	}

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

	return 0;
}

/*
 * Encode key into its hex representation
 */
static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
{
	unsigned int i;

	for(i = 0; i < size; i++) {
		sprintf(hex, "%02x", *key);
		hex += 2;
		key++;
	}
}

/*
 * 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;
	struct crypto_tfm *tfm;
	char *tmp;
	char *cipher;
	char *chainmode;
	char *ivmode;
	char *ivopts;
	unsigned int crypto_flags;
	unsigned int key_size;

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

	tmp = argv[0];
	cipher = strsep(&tmp, "-");
	chainmode = strsep(&tmp, "-");
	ivopts = strsep(&tmp, "-");
	ivmode = strsep(&ivopts, ":");

	if (tmp)
		DMWARN(PFX "Unexpected additional cipher options");

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

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

	cc->key_size = key_size;
	if ((!key_size && strcmp(argv[1], "-") != 0) ||
	    (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) {
		ti->error = PFX "Error decoding key";
		goto bad1;
	}

	/* Compatiblity mode for old dm-crypt cipher strings */
	if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
		chainmode = "cbc";
		ivmode = "plain";
	}

	/* Choose crypto_flags according to chainmode */
	if (strcmp(chainmode, "cbc") == 0)
		crypto_flags = CRYPTO_TFM_MODE_CBC;
	else if (strcmp(chainmode, "ecb") == 0)
		crypto_flags = CRYPTO_TFM_MODE_ECB;
	else {
		ti->error = PFX "Unknown chaining mode";
		goto bad1;
	}

	if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) {
		ti->error = PFX "This chaining mode requires an IV mechanism";
		goto bad1;
	}

	tfm = crypto_alloc_tfm(cipher, crypto_flags | CRYPTO_TFM_REQ_MAY_SLEEP);
	if (!tfm) {
		ti->error = PFX "Error allocating crypto tfm";
		goto bad1;
	}
	if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) {
		ti->error = PFX "Expected cipher algorithm";
		goto bad2;
	}

	cc->tfm = tfm;

	/*
	 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>".
	 * 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, "essiv") == 0)
		cc->iv_gen_ops = &crypt_iv_essiv_ops;
	else {
		ti->error = PFX "Invalid IV mode";
		goto bad2;
	}

	if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
	    cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
		goto bad2;

	if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv)
		/* at least a 64 bit sector number should fit in our buffer */
		cc->iv_size = max(crypto_tfm_alg_ivsize(tfm),
		                  (unsigned int)(sizeof(u64) / sizeof(u8)));
	else {
		cc->iv_size = 0;
		if (cc->iv_gen_ops) {
			DMWARN(PFX "Selected cipher does not support IVs");
			if (cc->iv_gen_ops->dtr)
				cc->iv_gen_ops->dtr(cc);
			cc->iv_gen_ops = NULL;
		}
	}

	cc->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
				     mempool_free_slab, _crypt_io_pool);
	if (!cc->io_pool) {
		ti->error = PFX "Cannot allocate crypt io mempool";
		goto bad3;
	}

	cc->page_pool = mempool_create(MIN_POOL_PAGES, mempool_alloc_page,
				       mempool_free_page, NULL);
	if (!cc->page_pool) {
		ti->error = PFX "Cannot allocate page mempool";
		goto bad4;
	}

	if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) {
		ti->error = PFX "Error setting key";
		goto bad5;
	}

	if (sscanf(argv[2], SECTOR_FORMAT, &cc->iv_offset) != 1) {
		ti->error = PFX "Invalid iv_offset sector";
		goto bad5;
	}

	if (sscanf(argv[4], SECTOR_FORMAT, &cc->start) != 1) {
		ti->error = PFX "Invalid device sector";
		goto bad5;
	}

	if (dm_get_device(ti, argv[3], cc->start, ti->len,
	                  dm_table_get_mode(ti->table), &cc->dev)) {
		ti->error = PFX "Device lookup failed";
		goto bad5;
	}

	if (ivmode && cc->iv_gen_ops) {
		if (ivopts)
			*(ivopts - 1) = ':';
		cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
		if (!cc->iv_mode) {
			ti->error = PFX "Error kmallocing iv_mode string";
			goto bad5;
		}
		strcpy(cc->iv_mode, ivmode);
	} else
		cc->iv_mode = NULL;

	ti->private = cc;
	return 0;

bad5:
	mempool_destroy(cc->page_pool);
bad4:
	mempool_destroy(cc->io_pool);
bad3:
	if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
		cc->iv_gen_ops->dtr(cc);
bad2:
	crypto_free_tfm(tfm);
bad1:
	kfree(cc);
	return -EINVAL;
}

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

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

	kfree(cc->iv_mode);
	if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
		cc->iv_gen_ops->dtr(cc);
	crypto_free_tfm(cc->tfm);
	dm_put_device(ti, cc->dev);
	kfree(cc);
}

static int crypt_endio(struct bio *bio, unsigned int done, int error)
{
	struct crypt_io *io = (struct crypt_io *) bio->bi_private;
	struct crypt_config *cc = (struct crypt_config *) io->target->private;

	if (bio_data_dir(bio) == WRITE) {
		/*
		 * free the processed pages, even if
		 * it's only a partially completed write
		 */
		crypt_free_buffer_pages(cc, bio, done);
	}

	if (bio->bi_size)
		return 1;

	bio_put(bio);

	/*
	 * successful reads are decrypted by the worker thread
	 */
	if ((bio_data_dir(bio) == READ)
	    && bio_flagged(bio, BIO_UPTODATE)) {
		kcryptd_queue_io(io);
		return 0;
	}

	dec_pending(io, error);
	return error;
}

static inline struct bio *
crypt_clone(struct crypt_config *cc, struct crypt_io *io, struct bio *bio,
            sector_t sector, unsigned int *bvec_idx,
            struct convert_context *ctx)
{
	struct bio *clone;

	if (bio_data_dir(bio) == WRITE) {
		clone = crypt_alloc_buffer(cc, bio->bi_size,
                                 io->first_clone, bvec_idx);
		if (clone) {
			ctx->bio_out = clone;
			if (crypt_convert(cc, ctx) < 0) {
				crypt_free_buffer_pages(cc, clone,
				                        clone->bi_size);
				bio_put(clone);
				return NULL;
			}
		}
	} else {
		/*
		 * 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_alloc(GFP_NOIO, bio_segments(bio));
		if (clone) {
			clone->bi_idx = 0;
			clone->bi_vcnt = bio_segments(bio);
			clone->bi_size = bio->bi_size;
			memcpy(clone->bi_io_vec, bio_iovec(bio),
			       sizeof(struct bio_vec) * clone->bi_vcnt);
		}
	}

	if (!clone)
		return NULL;

	clone->bi_private = io;
	clone->bi_end_io = crypt_endio;
	clone->bi_bdev = cc->dev->bdev;
	clone->bi_sector = cc->start + sector;
	clone->bi_rw = bio->bi_rw;

	return clone;
}

static int crypt_map(struct dm_target *ti, struct bio *bio,
		     union map_info *map_context)
{
	struct crypt_config *cc = (struct crypt_config *) ti->private;
	struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO);
	struct convert_context ctx;
	struct bio *clone;
	unsigned int remaining = bio->bi_size;
	sector_t sector = bio->bi_sector - ti->begin;
	unsigned int bvec_idx = 0;

	io->target = ti;
	io->bio = bio;
	io->first_clone = NULL;
	io->error = 0;
	atomic_set(&io->pending, 1); /* hold a reference */

	if (bio_data_dir(bio) == WRITE)
		crypt_convert_init(cc, &ctx, NULL, bio, sector, 1);

	/*
	 * 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_clone(cc, io, bio, sector, &bvec_idx, &ctx);
		if (!clone)
			goto cleanup;

		if (!io->first_clone) {
			/*
			 * hold a reference to the first clone, because it
			 * holds the bio_vec array and that can't be freed
			 * before all other clones are released
			 */
			bio_get(clone);
			io->first_clone = clone;
		}
		atomic_inc(&io->pending);

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

		generic_make_request(clone);

		/* out of memory -> run queues */
		if (remaining)
			blk_congestion_wait(bio_data_dir(clone), HZ/100);
	}

	/* drop reference, clones could have returned before we reach this */
	dec_pending(io, 0);
	return 0;

cleanup:
	if (io->first_clone) {
		dec_pending(io, -ENOMEM);
		return 0;
	}

	/* if no bio has been dispatched yet, we can directly return the error */
	mempool_free(io, cc->io_pool);
	return -ENOMEM;
}

static int crypt_status(struct dm_target *ti, status_type_t type,
			char *result, unsigned int maxlen)
{
	struct crypt_config *cc = (struct crypt_config *) ti->private;
	const char *cipher;
	const char *chainmode = NULL;
	unsigned int sz = 0;

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

	case STATUSTYPE_TABLE:
		cipher = crypto_tfm_alg_name(cc->tfm);

		switch(cc->tfm->crt_cipher.cit_mode) {
		case CRYPTO_TFM_MODE_CBC:
			chainmode = "cbc";
			break;
		case CRYPTO_TFM_MODE_ECB:
			chainmode = "ecb";
			break;
		default:
			BUG();
		}

		if (cc->iv_mode)
			DMEMIT("%s-%s-%s ", cipher, chainmode, cc->iv_mode);
		else
			DMEMIT("%s-%s ", cipher, chainmode);

		if (cc->key_size > 0) {
			if ((maxlen - sz) < ((cc->key_size << 1) + 1))
				return -ENOMEM;

			crypt_encode_key(result + sz, cc->key, cc->key_size);
			sz += cc->key_size << 1;
		} else {
			if (sz >= maxlen)
				return -ENOMEM;
			result[sz++] = '-';
		}

		DMEMIT(" " SECTOR_FORMAT " %s " SECTOR_FORMAT,
		       cc->iv_offset, cc->dev->name, cc->start);
		break;
	}
	return 0;
}

static struct target_type crypt_target = {
	.name   = "crypt",
	.version= {1, 1, 0},
	.module = THIS_MODULE,
	.ctr    = crypt_ctr,
	.dtr    = crypt_dtr,
	.map    = crypt_map,
	.status = crypt_status,
};

static int __init dm_crypt_init(void)
{
	int r;

	_crypt_io_pool = kmem_cache_create("dm-crypt_io",
	                                   sizeof(struct crypt_io),
	                                   0, 0, NULL, NULL);
	if (!_crypt_io_pool)
		return -ENOMEM;

	_kcryptd_workqueue = create_workqueue("kcryptd");
	if (!_kcryptd_workqueue) {
		r = -ENOMEM;
		DMERR(PFX "couldn't create kcryptd");
		goto bad1;
	}

	r = dm_register_target(&crypt_target);
	if (r < 0) {
		DMERR(PFX "register failed %d", r);
		goto bad2;
	}

	return 0;

bad2:
	destroy_workqueue(_kcryptd_workqueue);
bad1:
	kmem_cache_destroy(_crypt_io_pool);
	return r;
}

static void __exit dm_crypt_exit(void)
{
	int r = dm_unregister_target(&crypt_target);

	if (r < 0)
		DMERR(PFX "unregister failed %d", r);

	destroy_workqueue(_kcryptd_workqueue);
	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");