/drivers/md/dm-crypt.c
C | 1438 lines | 1028 code | 253 blank | 157 comment | 165 complexity | f9ed0b62ff80aa323966eb90b414e8ca MD5 | raw file
Possible License(s): CC-BY-SA-3.0, GPL-2.0, LGPL-2.0, AGPL-1.0
1/*
2 * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
3 * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
4 * Copyright (C) 2006-2009 Red Hat, Inc. All rights reserved.
5 *
6 * This file is released under the GPL.
7 */
8
9#include <linux/completion.h>
10#include <linux/err.h>
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/kernel.h>
14#include <linux/bio.h>
15#include <linux/blkdev.h>
16#include <linux/mempool.h>
17#include <linux/slab.h>
18#include <linux/crypto.h>
19#include <linux/workqueue.h>
20#include <linux/backing-dev.h>
21#include <asm/atomic.h>
22#include <linux/scatterlist.h>
23#include <asm/page.h>
24#include <asm/unaligned.h>
25
26#include <linux/device-mapper.h>
27
28#define DM_MSG_PREFIX "crypt"
29#define MESG_STR(x) x, sizeof(x)
30
31/*
32 * context holding the current state of a multi-part conversion
33 */
34struct convert_context {
35 struct completion restart;
36 struct bio *bio_in;
37 struct bio *bio_out;
38 unsigned int offset_in;
39 unsigned int offset_out;
40 unsigned int idx_in;
41 unsigned int idx_out;
42 sector_t sector;
43 atomic_t pending;
44};
45
46/*
47 * per bio private data
48 */
49struct dm_crypt_io {
50 struct dm_target *target;
51 struct bio *base_bio;
52 struct work_struct work;
53
54 struct convert_context ctx;
55
56 atomic_t pending;
57 int error;
58 sector_t sector;
59 struct dm_crypt_io *base_io;
60};
61
62struct dm_crypt_request {
63 struct convert_context *ctx;
64 struct scatterlist sg_in;
65 struct scatterlist sg_out;
66};
67
68struct crypt_config;
69
70struct crypt_iv_operations {
71 int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
72 const char *opts);
73 void (*dtr)(struct crypt_config *cc);
74 int (*init)(struct crypt_config *cc);
75 int (*wipe)(struct crypt_config *cc);
76 int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
77};
78
79struct iv_essiv_private {
80 struct crypto_cipher *tfm;
81 struct crypto_hash *hash_tfm;
82 u8 *salt;
83};
84
85struct iv_benbi_private {
86 int shift;
87};
88
89/*
90 * Crypt: maps a linear range of a block device
91 * and encrypts / decrypts at the same time.
92 */
93enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
94struct crypt_config {
95 struct dm_dev *dev;
96 sector_t start;
97
98 /*
99 * pool for per bio private data, crypto requests and
100 * encryption requeusts/buffer pages
101 */
102 mempool_t *io_pool;
103 mempool_t *req_pool;
104 mempool_t *page_pool;
105 struct bio_set *bs;
106
107 struct workqueue_struct *io_queue;
108 struct workqueue_struct *crypt_queue;
109
110 /*
111 * crypto related data
112 */
113 struct crypt_iv_operations *iv_gen_ops;
114 char *iv_mode;
115 union {
116 struct iv_essiv_private essiv;
117 struct iv_benbi_private benbi;
118 } iv_gen_private;
119 sector_t iv_offset;
120 unsigned int iv_size;
121
122 /*
123 * Layout of each crypto request:
124 *
125 * struct ablkcipher_request
126 * context
127 * padding
128 * struct dm_crypt_request
129 * padding
130 * IV
131 *
132 * The padding is added so that dm_crypt_request and the IV are
133 * correctly aligned.
134 */
135 unsigned int dmreq_start;
136 struct ablkcipher_request *req;
137
138 char cipher[CRYPTO_MAX_ALG_NAME];
139 char chainmode[CRYPTO_MAX_ALG_NAME];
140 struct crypto_ablkcipher *tfm;
141 unsigned long flags;
142 unsigned int key_size;
143 u8 key[0];
144};
145
146#define MIN_IOS 16
147#define MIN_POOL_PAGES 32
148#define MIN_BIO_PAGES 8
149
150static struct kmem_cache *_crypt_io_pool;
151
152static void clone_init(struct dm_crypt_io *, struct bio *);
153static void kcryptd_queue_crypt(struct dm_crypt_io *io);
154
155/*
156 * Different IV generation algorithms:
157 *
158 * plain: the initial vector is the 32-bit little-endian version of the sector
159 * number, padded with zeros if necessary.
160 *
161 * plain64: the initial vector is the 64-bit little-endian version of the sector
162 * number, padded with zeros if necessary.
163 *
164 * essiv: "encrypted sector|salt initial vector", the sector number is
165 * encrypted with the bulk cipher using a salt as key. The salt
166 * should be derived from the bulk cipher's key via hashing.
167 *
168 * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
169 * (needed for LRW-32-AES and possible other narrow block modes)
170 *
171 * null: the initial vector is always zero. Provides compatibility with
172 * obsolete loop_fish2 devices. Do not use for new devices.
173 *
174 * plumb: unimplemented, see:
175 * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
176 */
177
178static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
179{
180 memset(iv, 0, cc->iv_size);
181 *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
182
183 return 0;
184}
185
186static int crypt_iv_plain64_gen(struct crypt_config *cc, u8 *iv,
187 sector_t sector)
188{
189 memset(iv, 0, cc->iv_size);
190 *(u64 *)iv = cpu_to_le64(sector);
191
192 return 0;
193}
194
195/* Initialise ESSIV - compute salt but no local memory allocations */
196static int crypt_iv_essiv_init(struct crypt_config *cc)
197{
198 struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
199 struct hash_desc desc;
200 struct scatterlist sg;
201 int err;
202
203 sg_init_one(&sg, cc->key, cc->key_size);
204 desc.tfm = essiv->hash_tfm;
205 desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
206
207 err = crypto_hash_digest(&desc, &sg, cc->key_size, essiv->salt);
208 if (err)
209 return err;
210
211 return crypto_cipher_setkey(essiv->tfm, essiv->salt,
212 crypto_hash_digestsize(essiv->hash_tfm));
213}
214
215/* Wipe salt and reset key derived from volume key */
216static int crypt_iv_essiv_wipe(struct crypt_config *cc)
217{
218 struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
219 unsigned salt_size = crypto_hash_digestsize(essiv->hash_tfm);
220
221 memset(essiv->salt, 0, salt_size);
222
223 return crypto_cipher_setkey(essiv->tfm, essiv->salt, salt_size);
224}
225
226static void crypt_iv_essiv_dtr(struct crypt_config *cc)
227{
228 struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
229
230 crypto_free_cipher(essiv->tfm);
231 essiv->tfm = NULL;
232
233 crypto_free_hash(essiv->hash_tfm);
234 essiv->hash_tfm = NULL;
235
236 kzfree(essiv->salt);
237 essiv->salt = NULL;
238}
239
240static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
241 const char *opts)
242{
243 struct crypto_cipher *essiv_tfm = NULL;
244 struct crypto_hash *hash_tfm = NULL;
245 u8 *salt = NULL;
246 int err;
247
248 if (!opts) {
249 ti->error = "Digest algorithm missing for ESSIV mode";
250 return -EINVAL;
251 }
252
253 /* Allocate hash algorithm */
254 hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
255 if (IS_ERR(hash_tfm)) {
256 ti->error = "Error initializing ESSIV hash";
257 err = PTR_ERR(hash_tfm);
258 goto bad;
259 }
260
261 salt = kzalloc(crypto_hash_digestsize(hash_tfm), GFP_KERNEL);
262 if (!salt) {
263 ti->error = "Error kmallocing salt storage in ESSIV";
264 err = -ENOMEM;
265 goto bad;
266 }
267
268 /* Allocate essiv_tfm */
269 essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
270 if (IS_ERR(essiv_tfm)) {
271 ti->error = "Error allocating crypto tfm for ESSIV";
272 err = PTR_ERR(essiv_tfm);
273 goto bad;
274 }
275 if (crypto_cipher_blocksize(essiv_tfm) !=
276 crypto_ablkcipher_ivsize(cc->tfm)) {
277 ti->error = "Block size of ESSIV cipher does "
278 "not match IV size of block cipher";
279 err = -EINVAL;
280 goto bad;
281 }
282
283 cc->iv_gen_private.essiv.salt = salt;
284 cc->iv_gen_private.essiv.tfm = essiv_tfm;
285 cc->iv_gen_private.essiv.hash_tfm = hash_tfm;
286
287 return 0;
288
289bad:
290 if (essiv_tfm && !IS_ERR(essiv_tfm))
291 crypto_free_cipher(essiv_tfm);
292 if (hash_tfm && !IS_ERR(hash_tfm))
293 crypto_free_hash(hash_tfm);
294 kfree(salt);
295 return err;
296}
297
298static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
299{
300 memset(iv, 0, cc->iv_size);
301 *(u64 *)iv = cpu_to_le64(sector);
302 crypto_cipher_encrypt_one(cc->iv_gen_private.essiv.tfm, iv, iv);
303 return 0;
304}
305
306static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
307 const char *opts)
308{
309 unsigned bs = crypto_ablkcipher_blocksize(cc->tfm);
310 int log = ilog2(bs);
311
312 /* we need to calculate how far we must shift the sector count
313 * to get the cipher block count, we use this shift in _gen */
314
315 if (1 << log != bs) {
316 ti->error = "cypher blocksize is not a power of 2";
317 return -EINVAL;
318 }
319
320 if (log > 9) {
321 ti->error = "cypher blocksize is > 512";
322 return -EINVAL;
323 }
324
325 cc->iv_gen_private.benbi.shift = 9 - log;
326
327 return 0;
328}
329
330static void crypt_iv_benbi_dtr(struct crypt_config *cc)
331{
332}
333
334static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
335{
336 __be64 val;
337
338 memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
339
340 val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi.shift) + 1);
341 put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
342
343 return 0;
344}
345
346static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
347{
348 memset(iv, 0, cc->iv_size);
349
350 return 0;
351}
352
353static struct crypt_iv_operations crypt_iv_plain_ops = {
354 .generator = crypt_iv_plain_gen
355};
356
357static struct crypt_iv_operations crypt_iv_plain64_ops = {
358 .generator = crypt_iv_plain64_gen
359};
360
361static struct crypt_iv_operations crypt_iv_essiv_ops = {
362 .ctr = crypt_iv_essiv_ctr,
363 .dtr = crypt_iv_essiv_dtr,
364 .init = crypt_iv_essiv_init,
365 .wipe = crypt_iv_essiv_wipe,
366 .generator = crypt_iv_essiv_gen
367};
368
369static struct crypt_iv_operations crypt_iv_benbi_ops = {
370 .ctr = crypt_iv_benbi_ctr,
371 .dtr = crypt_iv_benbi_dtr,
372 .generator = crypt_iv_benbi_gen
373};
374
375static struct crypt_iv_operations crypt_iv_null_ops = {
376 .generator = crypt_iv_null_gen
377};
378
379static void crypt_convert_init(struct crypt_config *cc,
380 struct convert_context *ctx,
381 struct bio *bio_out, struct bio *bio_in,
382 sector_t sector)
383{
384 ctx->bio_in = bio_in;
385 ctx->bio_out = bio_out;
386 ctx->offset_in = 0;
387 ctx->offset_out = 0;
388 ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
389 ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
390 ctx->sector = sector + cc->iv_offset;
391 init_completion(&ctx->restart);
392}
393
394static struct dm_crypt_request *dmreq_of_req(struct crypt_config *cc,
395 struct ablkcipher_request *req)
396{
397 return (struct dm_crypt_request *)((char *)req + cc->dmreq_start);
398}
399
400static struct ablkcipher_request *req_of_dmreq(struct crypt_config *cc,
401 struct dm_crypt_request *dmreq)
402{
403 return (struct ablkcipher_request *)((char *)dmreq - cc->dmreq_start);
404}
405
406static int crypt_convert_block(struct crypt_config *cc,
407 struct convert_context *ctx,
408 struct ablkcipher_request *req)
409{
410 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
411 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
412 struct dm_crypt_request *dmreq;
413 u8 *iv;
414 int r = 0;
415
416 dmreq = dmreq_of_req(cc, req);
417 iv = (u8 *)ALIGN((unsigned long)(dmreq + 1),
418 crypto_ablkcipher_alignmask(cc->tfm) + 1);
419
420 dmreq->ctx = ctx;
421 sg_init_table(&dmreq->sg_in, 1);
422 sg_set_page(&dmreq->sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT,
423 bv_in->bv_offset + ctx->offset_in);
424
425 sg_init_table(&dmreq->sg_out, 1);
426 sg_set_page(&dmreq->sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT,
427 bv_out->bv_offset + ctx->offset_out);
428
429 ctx->offset_in += 1 << SECTOR_SHIFT;
430 if (ctx->offset_in >= bv_in->bv_len) {
431 ctx->offset_in = 0;
432 ctx->idx_in++;
433 }
434
435 ctx->offset_out += 1 << SECTOR_SHIFT;
436 if (ctx->offset_out >= bv_out->bv_len) {
437 ctx->offset_out = 0;
438 ctx->idx_out++;
439 }
440
441 if (cc->iv_gen_ops) {
442 r = cc->iv_gen_ops->generator(cc, iv, ctx->sector);
443 if (r < 0)
444 return r;
445 }
446
447 ablkcipher_request_set_crypt(req, &dmreq->sg_in, &dmreq->sg_out,
448 1 << SECTOR_SHIFT, iv);
449
450 if (bio_data_dir(ctx->bio_in) == WRITE)
451 r = crypto_ablkcipher_encrypt(req);
452 else
453 r = crypto_ablkcipher_decrypt(req);
454
455 return r;
456}
457
458static void kcryptd_async_done(struct crypto_async_request *async_req,
459 int error);
460static void crypt_alloc_req(struct crypt_config *cc,
461 struct convert_context *ctx)
462{
463 if (!cc->req)
464 cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);
465 ablkcipher_request_set_tfm(cc->req, cc->tfm);
466 ablkcipher_request_set_callback(cc->req, CRYPTO_TFM_REQ_MAY_BACKLOG |
467 CRYPTO_TFM_REQ_MAY_SLEEP,
468 kcryptd_async_done,
469 dmreq_of_req(cc, cc->req));
470}
471
472/*
473 * Encrypt / decrypt data from one bio to another one (can be the same one)
474 */
475static int crypt_convert(struct crypt_config *cc,
476 struct convert_context *ctx)
477{
478 int r;
479
480 atomic_set(&ctx->pending, 1);
481
482 while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
483 ctx->idx_out < ctx->bio_out->bi_vcnt) {
484
485 crypt_alloc_req(cc, ctx);
486
487 atomic_inc(&ctx->pending);
488
489 r = crypt_convert_block(cc, ctx, cc->req);
490
491 switch (r) {
492 /* async */
493 case -EBUSY:
494 wait_for_completion(&ctx->restart);
495 INIT_COMPLETION(ctx->restart);
496 /* fall through*/
497 case -EINPROGRESS:
498 cc->req = NULL;
499 ctx->sector++;
500 continue;
501
502 /* sync */
503 case 0:
504 atomic_dec(&ctx->pending);
505 ctx->sector++;
506 cond_resched();
507 continue;
508
509 /* error */
510 default:
511 atomic_dec(&ctx->pending);
512 return r;
513 }
514 }
515
516 return 0;
517}
518
519static void dm_crypt_bio_destructor(struct bio *bio)
520{
521 struct dm_crypt_io *io = bio->bi_private;
522 struct crypt_config *cc = io->target->private;
523
524 bio_free(bio, cc->bs);
525}
526
527/*
528 * Generate a new unfragmented bio with the given size
529 * This should never violate the device limitations
530 * May return a smaller bio when running out of pages, indicated by
531 * *out_of_pages set to 1.
532 */
533static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size,
534 unsigned *out_of_pages)
535{
536 struct crypt_config *cc = io->target->private;
537 struct bio *clone;
538 unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
539 gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
540 unsigned i, len;
541 struct page *page;
542
543 clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
544 if (!clone)
545 return NULL;
546
547 clone_init(io, clone);
548 *out_of_pages = 0;
549
550 for (i = 0; i < nr_iovecs; i++) {
551 page = mempool_alloc(cc->page_pool, gfp_mask);
552 if (!page) {
553 *out_of_pages = 1;
554 break;
555 }
556
557 /*
558 * if additional pages cannot be allocated without waiting,
559 * return a partially allocated bio, the caller will then try
560 * to allocate additional bios while submitting this partial bio
561 */
562 if (i == (MIN_BIO_PAGES - 1))
563 gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
564
565 len = (size > PAGE_SIZE) ? PAGE_SIZE : size;
566
567 if (!bio_add_page(clone, page, len, 0)) {
568 mempool_free(page, cc->page_pool);
569 break;
570 }
571
572 size -= len;
573 }
574
575 if (!clone->bi_size) {
576 bio_put(clone);
577 return NULL;
578 }
579
580 return clone;
581}
582
583static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
584{
585 unsigned int i;
586 struct bio_vec *bv;
587
588 for (i = 0; i < clone->bi_vcnt; i++) {
589 bv = bio_iovec_idx(clone, i);
590 BUG_ON(!bv->bv_page);
591 mempool_free(bv->bv_page, cc->page_pool);
592 bv->bv_page = NULL;
593 }
594}
595
596static struct dm_crypt_io *crypt_io_alloc(struct dm_target *ti,
597 struct bio *bio, sector_t sector)
598{
599 struct crypt_config *cc = ti->private;
600 struct dm_crypt_io *io;
601
602 io = mempool_alloc(cc->io_pool, GFP_NOIO);
603 io->target = ti;
604 io->base_bio = bio;
605 io->sector = sector;
606 io->error = 0;
607 io->base_io = NULL;
608 atomic_set(&io->pending, 0);
609
610 return io;
611}
612
613static void crypt_inc_pending(struct dm_crypt_io *io)
614{
615 atomic_inc(&io->pending);
616}
617
618/*
619 * One of the bios was finished. Check for completion of
620 * the whole request and correctly clean up the buffer.
621 * If base_io is set, wait for the last fragment to complete.
622 */
623static void crypt_dec_pending(struct dm_crypt_io *io)
624{
625 struct crypt_config *cc = io->target->private;
626 struct bio *base_bio = io->base_bio;
627 struct dm_crypt_io *base_io = io->base_io;
628 int error = io->error;
629
630 if (!atomic_dec_and_test(&io->pending))
631 return;
632
633 mempool_free(io, cc->io_pool);
634
635 if (likely(!base_io))
636 bio_endio(base_bio, error);
637 else {
638 if (error && !base_io->error)
639 base_io->error = error;
640 crypt_dec_pending(base_io);
641 }
642}
643
644/*
645 * kcryptd/kcryptd_io:
646 *
647 * Needed because it would be very unwise to do decryption in an
648 * interrupt context.
649 *
650 * kcryptd performs the actual encryption or decryption.
651 *
652 * kcryptd_io performs the IO submission.
653 *
654 * They must be separated as otherwise the final stages could be
655 * starved by new requests which can block in the first stages due
656 * to memory allocation.
657 */
658static void crypt_endio(struct bio *clone, int error)
659{
660 struct dm_crypt_io *io = clone->bi_private;
661 struct crypt_config *cc = io->target->private;
662 unsigned rw = bio_data_dir(clone);
663
664 if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
665 error = -EIO;
666
667 /*
668 * free the processed pages
669 */
670 if (rw == WRITE)
671 crypt_free_buffer_pages(cc, clone);
672
673 bio_put(clone);
674
675 if (rw == READ && !error) {
676 kcryptd_queue_crypt(io);
677 return;
678 }
679
680 if (unlikely(error))
681 io->error = error;
682
683 crypt_dec_pending(io);
684}
685
686static void clone_init(struct dm_crypt_io *io, struct bio *clone)
687{
688 struct crypt_config *cc = io->target->private;
689
690 clone->bi_private = io;
691 clone->bi_end_io = crypt_endio;
692 clone->bi_bdev = cc->dev->bdev;
693 clone->bi_rw = io->base_bio->bi_rw;
694 clone->bi_destructor = dm_crypt_bio_destructor;
695}
696
697static void kcryptd_io_read(struct dm_crypt_io *io)
698{
699 struct crypt_config *cc = io->target->private;
700 struct bio *base_bio = io->base_bio;
701 struct bio *clone;
702
703 crypt_inc_pending(io);
704
705 /*
706 * The block layer might modify the bvec array, so always
707 * copy the required bvecs because we need the original
708 * one in order to decrypt the whole bio data *afterwards*.
709 */
710 clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
711 if (unlikely(!clone)) {
712 io->error = -ENOMEM;
713 crypt_dec_pending(io);
714 return;
715 }
716
717 clone_init(io, clone);
718 clone->bi_idx = 0;
719 clone->bi_vcnt = bio_segments(base_bio);
720 clone->bi_size = base_bio->bi_size;
721 clone->bi_sector = cc->start + io->sector;
722 memcpy(clone->bi_io_vec, bio_iovec(base_bio),
723 sizeof(struct bio_vec) * clone->bi_vcnt);
724
725 generic_make_request(clone);
726}
727
728static void kcryptd_io_write(struct dm_crypt_io *io)
729{
730 struct bio *clone = io->ctx.bio_out;
731 generic_make_request(clone);
732}
733
734static void kcryptd_io(struct work_struct *work)
735{
736 struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
737
738 if (bio_data_dir(io->base_bio) == READ)
739 kcryptd_io_read(io);
740 else
741 kcryptd_io_write(io);
742}
743
744static void kcryptd_queue_io(struct dm_crypt_io *io)
745{
746 struct crypt_config *cc = io->target->private;
747
748 INIT_WORK(&io->work, kcryptd_io);
749 queue_work(cc->io_queue, &io->work);
750}
751
752static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io,
753 int error, int async)
754{
755 struct bio *clone = io->ctx.bio_out;
756 struct crypt_config *cc = io->target->private;
757
758 if (unlikely(error < 0)) {
759 crypt_free_buffer_pages(cc, clone);
760 bio_put(clone);
761 io->error = -EIO;
762 crypt_dec_pending(io);
763 return;
764 }
765
766 /* crypt_convert should have filled the clone bio */
767 BUG_ON(io->ctx.idx_out < clone->bi_vcnt);
768
769 clone->bi_sector = cc->start + io->sector;
770
771 if (async)
772 kcryptd_queue_io(io);
773 else
774 generic_make_request(clone);
775}
776
777static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
778{
779 struct crypt_config *cc = io->target->private;
780 struct bio *clone;
781 struct dm_crypt_io *new_io;
782 int crypt_finished;
783 unsigned out_of_pages = 0;
784 unsigned remaining = io->base_bio->bi_size;
785 sector_t sector = io->sector;
786 int r;
787
788 /*
789 * Prevent io from disappearing until this function completes.
790 */
791 crypt_inc_pending(io);
792 crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector);
793
794 /*
795 * The allocated buffers can be smaller than the whole bio,
796 * so repeat the whole process until all the data can be handled.
797 */
798 while (remaining) {
799 clone = crypt_alloc_buffer(io, remaining, &out_of_pages);
800 if (unlikely(!clone)) {
801 io->error = -ENOMEM;
802 break;
803 }
804
805 io->ctx.bio_out = clone;
806 io->ctx.idx_out = 0;
807
808 remaining -= clone->bi_size;
809 sector += bio_sectors(clone);
810
811 crypt_inc_pending(io);
812 r = crypt_convert(cc, &io->ctx);
813 crypt_finished = atomic_dec_and_test(&io->ctx.pending);
814
815 /* Encryption was already finished, submit io now */
816 if (crypt_finished) {
817 kcryptd_crypt_write_io_submit(io, r, 0);
818
819 /*
820 * If there was an error, do not try next fragments.
821 * For async, error is processed in async handler.
822 */
823 if (unlikely(r < 0))
824 break;
825
826 io->sector = sector;
827 }
828
829 /*
830 * Out of memory -> run queues
831 * But don't wait if split was due to the io size restriction
832 */
833 if (unlikely(out_of_pages))
834 congestion_wait(BLK_RW_ASYNC, HZ/100);
835
836 /*
837 * With async crypto it is unsafe to share the crypto context
838 * between fragments, so switch to a new dm_crypt_io structure.
839 */
840 if (unlikely(!crypt_finished && remaining)) {
841 new_io = crypt_io_alloc(io->target, io->base_bio,
842 sector);
843 crypt_inc_pending(new_io);
844 crypt_convert_init(cc, &new_io->ctx, NULL,
845 io->base_bio, sector);
846 new_io->ctx.idx_in = io->ctx.idx_in;
847 new_io->ctx.offset_in = io->ctx.offset_in;
848
849 /*
850 * Fragments after the first use the base_io
851 * pending count.
852 */
853 if (!io->base_io)
854 new_io->base_io = io;
855 else {
856 new_io->base_io = io->base_io;
857 crypt_inc_pending(io->base_io);
858 crypt_dec_pending(io);
859 }
860
861 io = new_io;
862 }
863 }
864
865 crypt_dec_pending(io);
866}
867
868static void kcryptd_crypt_read_done(struct dm_crypt_io *io, int error)
869{
870 if (unlikely(error < 0))
871 io->error = -EIO;
872
873 crypt_dec_pending(io);
874}
875
876static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)
877{
878 struct crypt_config *cc = io->target->private;
879 int r = 0;
880
881 crypt_inc_pending(io);
882
883 crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,
884 io->sector);
885
886 r = crypt_convert(cc, &io->ctx);
887
888 if (atomic_dec_and_test(&io->ctx.pending))
889 kcryptd_crypt_read_done(io, r);
890
891 crypt_dec_pending(io);
892}
893
894static void kcryptd_async_done(struct crypto_async_request *async_req,
895 int error)
896{
897 struct dm_crypt_request *dmreq = async_req->data;
898 struct convert_context *ctx = dmreq->ctx;
899 struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
900 struct crypt_config *cc = io->target->private;
901
902 if (error == -EINPROGRESS) {
903 complete(&ctx->restart);
904 return;
905 }
906
907 mempool_free(req_of_dmreq(cc, dmreq), cc->req_pool);
908
909 if (!atomic_dec_and_test(&ctx->pending))
910 return;
911
912 if (bio_data_dir(io->base_bio) == READ)
913 kcryptd_crypt_read_done(io, error);
914 else
915 kcryptd_crypt_write_io_submit(io, error, 1);
916}
917
918static void kcryptd_crypt(struct work_struct *work)
919{
920 struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
921
922 if (bio_data_dir(io->base_bio) == READ)
923 kcryptd_crypt_read_convert(io);
924 else
925 kcryptd_crypt_write_convert(io);
926}
927
928static void kcryptd_queue_crypt(struct dm_crypt_io *io)
929{
930 struct crypt_config *cc = io->target->private;
931
932 INIT_WORK(&io->work, kcryptd_crypt);
933 queue_work(cc->crypt_queue, &io->work);
934}
935
936/*
937 * Decode key from its hex representation
938 */
939static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
940{
941 char buffer[3];
942 char *endp;
943 unsigned int i;
944
945 buffer[2] = '\0';
946
947 for (i = 0; i < size; i++) {
948 buffer[0] = *hex++;
949 buffer[1] = *hex++;
950
951 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
952
953 if (endp != &buffer[2])
954 return -EINVAL;
955 }
956
957 if (*hex != '\0')
958 return -EINVAL;
959
960 return 0;
961}
962
963/*
964 * Encode key into its hex representation
965 */
966static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
967{
968 unsigned int i;
969
970 for (i = 0; i < size; i++) {
971 sprintf(hex, "%02x", *key);
972 hex += 2;
973 key++;
974 }
975}
976
977static int crypt_set_key(struct crypt_config *cc, char *key)
978{
979 unsigned key_size = strlen(key) >> 1;
980
981 if (cc->key_size && cc->key_size != key_size)
982 return -EINVAL;
983
984 cc->key_size = key_size; /* initial settings */
985
986 if ((!key_size && strcmp(key, "-")) ||
987 (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
988 return -EINVAL;
989
990 set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
991
992 return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
993}
994
995static int crypt_wipe_key(struct crypt_config *cc)
996{
997 clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
998 memset(&cc->key, 0, cc->key_size * sizeof(u8));
999 return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
1000}
1001
1002/*
1003 * Construct an encryption mapping:
1004 * <cipher> <key> <iv_offset> <dev_path> <start>
1005 */
1006static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1007{
1008 struct crypt_config *cc;
1009 struct crypto_ablkcipher *tfm;
1010 char *tmp;
1011 char *cipher;
1012 char *chainmode;
1013 char *ivmode;
1014 char *ivopts;
1015 unsigned int key_size;
1016 unsigned long long tmpll;
1017
1018 if (argc != 5) {
1019 ti->error = "Not enough arguments";
1020 return -EINVAL;
1021 }
1022
1023 tmp = argv[0];
1024 cipher = strsep(&tmp, "-");
1025 chainmode = strsep(&tmp, "-");
1026 ivopts = strsep(&tmp, "-");
1027 ivmode = strsep(&ivopts, ":");
1028
1029 if (tmp)
1030 DMWARN("Unexpected additional cipher options");
1031
1032 key_size = strlen(argv[1]) >> 1;
1033
1034 cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
1035 if (cc == NULL) {
1036 ti->error =
1037 "Cannot allocate transparent encryption context";
1038 return -ENOMEM;
1039 }
1040
1041 /* Compatibility mode for old dm-crypt cipher strings */
1042 if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
1043 chainmode = "cbc";
1044 ivmode = "plain";
1045 }
1046
1047 if (strcmp(chainmode, "ecb") && !ivmode) {
1048 ti->error = "This chaining mode requires an IV mechanism";
1049 goto bad_cipher;
1050 }
1051
1052 if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)",
1053 chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) {
1054 ti->error = "Chain mode + cipher name is too long";
1055 goto bad_cipher;
1056 }
1057
1058 tfm = crypto_alloc_ablkcipher(cc->cipher, 0, 0);
1059 if (IS_ERR(tfm)) {
1060 ti->error = "Error allocating crypto tfm";
1061 goto bad_cipher;
1062 }
1063
1064 strcpy(cc->cipher, cipher);
1065 strcpy(cc->chainmode, chainmode);
1066 cc->tfm = tfm;
1067
1068 if (crypt_set_key(cc, argv[1]) < 0) {
1069 ti->error = "Error decoding and setting key";
1070 goto bad_ivmode;
1071 }
1072
1073 /*
1074 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
1075 * See comments at iv code
1076 */
1077
1078 if (ivmode == NULL)
1079 cc->iv_gen_ops = NULL;
1080 else if (strcmp(ivmode, "plain") == 0)
1081 cc->iv_gen_ops = &crypt_iv_plain_ops;
1082 else if (strcmp(ivmode, "plain64") == 0)
1083 cc->iv_gen_ops = &crypt_iv_plain64_ops;
1084 else if (strcmp(ivmode, "essiv") == 0)
1085 cc->iv_gen_ops = &crypt_iv_essiv_ops;
1086 else if (strcmp(ivmode, "benbi") == 0)
1087 cc->iv_gen_ops = &crypt_iv_benbi_ops;
1088 else if (strcmp(ivmode, "null") == 0)
1089 cc->iv_gen_ops = &crypt_iv_null_ops;
1090 else {
1091 ti->error = "Invalid IV mode";
1092 goto bad_ivmode;
1093 }
1094
1095 if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
1096 cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
1097 goto bad_ivmode;
1098
1099 if (cc->iv_gen_ops && cc->iv_gen_ops->init &&
1100 cc->iv_gen_ops->init(cc) < 0) {
1101 ti->error = "Error initialising IV";
1102 goto bad_slab_pool;
1103 }
1104
1105 cc->iv_size = crypto_ablkcipher_ivsize(tfm);
1106 if (cc->iv_size)
1107 /* at least a 64 bit sector number should fit in our buffer */
1108 cc->iv_size = max(cc->iv_size,
1109 (unsigned int)(sizeof(u64) / sizeof(u8)));
1110 else {
1111 if (cc->iv_gen_ops) {
1112 DMWARN("Selected cipher does not support IVs");
1113 if (cc->iv_gen_ops->dtr)
1114 cc->iv_gen_ops->dtr(cc);
1115 cc->iv_gen_ops = NULL;
1116 }
1117 }
1118
1119 cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
1120 if (!cc->io_pool) {
1121 ti->error = "Cannot allocate crypt io mempool";
1122 goto bad_slab_pool;
1123 }
1124
1125 cc->dmreq_start = sizeof(struct ablkcipher_request);
1126 cc->dmreq_start += crypto_ablkcipher_reqsize(tfm);
1127 cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment());
1128 cc->dmreq_start += crypto_ablkcipher_alignmask(tfm) &
1129 ~(crypto_tfm_ctx_alignment() - 1);
1130
1131 cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
1132 sizeof(struct dm_crypt_request) + cc->iv_size);
1133 if (!cc->req_pool) {
1134 ti->error = "Cannot allocate crypt request mempool";
1135 goto bad_req_pool;
1136 }
1137 cc->req = NULL;
1138
1139 cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
1140 if (!cc->page_pool) {
1141 ti->error = "Cannot allocate page mempool";
1142 goto bad_page_pool;
1143 }
1144
1145 cc->bs = bioset_create(MIN_IOS, 0);
1146 if (!cc->bs) {
1147 ti->error = "Cannot allocate crypt bioset";
1148 goto bad_bs;
1149 }
1150
1151 if (sscanf(argv[2], "%llu", &tmpll) != 1) {
1152 ti->error = "Invalid iv_offset sector";
1153 goto bad_device;
1154 }
1155 cc->iv_offset = tmpll;
1156
1157 if (sscanf(argv[4], "%llu", &tmpll) != 1) {
1158 ti->error = "Invalid device sector";
1159 goto bad_device;
1160 }
1161 cc->start = tmpll;
1162
1163 if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &cc->dev)) {
1164 ti->error = "Device lookup failed";
1165 goto bad_device;
1166 }
1167
1168 if (ivmode && cc->iv_gen_ops) {
1169 if (ivopts)
1170 *(ivopts - 1) = ':';
1171 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
1172 if (!cc->iv_mode) {
1173 ti->error = "Error kmallocing iv_mode string";
1174 goto bad_ivmode_string;
1175 }
1176 strcpy(cc->iv_mode, ivmode);
1177 } else
1178 cc->iv_mode = NULL;
1179
1180 cc->io_queue = create_singlethread_workqueue("kcryptd_io");
1181 if (!cc->io_queue) {
1182 ti->error = "Couldn't create kcryptd io queue";
1183 goto bad_io_queue;
1184 }
1185
1186 cc->crypt_queue = create_singlethread_workqueue("kcryptd");
1187 if (!cc->crypt_queue) {
1188 ti->error = "Couldn't create kcryptd queue";
1189 goto bad_crypt_queue;
1190 }
1191
1192 ti->num_flush_requests = 1;
1193 ti->private = cc;
1194 return 0;
1195
1196bad_crypt_queue:
1197 destroy_workqueue(cc->io_queue);
1198bad_io_queue:
1199 kfree(cc->iv_mode);
1200bad_ivmode_string:
1201 dm_put_device(ti, cc->dev);
1202bad_device:
1203 bioset_free(cc->bs);
1204bad_bs:
1205 mempool_destroy(cc->page_pool);
1206bad_page_pool:
1207 mempool_destroy(cc->req_pool);
1208bad_req_pool:
1209 mempool_destroy(cc->io_pool);
1210bad_slab_pool:
1211 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
1212 cc->iv_gen_ops->dtr(cc);
1213bad_ivmode:
1214 crypto_free_ablkcipher(tfm);
1215bad_cipher:
1216 /* Must zero key material before freeing */
1217 kzfree(cc);
1218 return -EINVAL;
1219}
1220
1221static void crypt_dtr(struct dm_target *ti)
1222{
1223 struct crypt_config *cc = (struct crypt_config *) ti->private;
1224
1225 destroy_workqueue(cc->io_queue);
1226 destroy_workqueue(cc->crypt_queue);
1227
1228 if (cc->req)
1229 mempool_free(cc->req, cc->req_pool);
1230
1231 bioset_free(cc->bs);
1232 mempool_destroy(cc->page_pool);
1233 mempool_destroy(cc->req_pool);
1234 mempool_destroy(cc->io_pool);
1235
1236 kfree(cc->iv_mode);
1237 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
1238 cc->iv_gen_ops->dtr(cc);
1239 crypto_free_ablkcipher(cc->tfm);
1240 dm_put_device(ti, cc->dev);
1241
1242 /* Must zero key material before freeing */
1243 kzfree(cc);
1244}
1245
1246static int crypt_map(struct dm_target *ti, struct bio *bio,
1247 union map_info *map_context)
1248{
1249 struct dm_crypt_io *io;
1250 struct crypt_config *cc;
1251
1252 if (unlikely(bio_empty_barrier(bio))) {
1253 cc = ti->private;
1254 bio->bi_bdev = cc->dev->bdev;
1255 return DM_MAPIO_REMAPPED;
1256 }
1257
1258 io = crypt_io_alloc(ti, bio, bio->bi_sector - ti->begin);
1259
1260 if (bio_data_dir(io->base_bio) == READ)
1261 kcryptd_queue_io(io);
1262 else
1263 kcryptd_queue_crypt(io);
1264
1265 return DM_MAPIO_SUBMITTED;
1266}
1267
1268static int crypt_status(struct dm_target *ti, status_type_t type,
1269 char *result, unsigned int maxlen)
1270{
1271 struct crypt_config *cc = (struct crypt_config *) ti->private;
1272 unsigned int sz = 0;
1273
1274 switch (type) {
1275 case STATUSTYPE_INFO:
1276 result[0] = '\0';
1277 break;
1278
1279 case STATUSTYPE_TABLE:
1280 if (cc->iv_mode)
1281 DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
1282 cc->iv_mode);
1283 else
1284 DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
1285
1286 if (cc->key_size > 0) {
1287 if ((maxlen - sz) < ((cc->key_size << 1) + 1))
1288 return -ENOMEM;
1289
1290 crypt_encode_key(result + sz, cc->key, cc->key_size);
1291 sz += cc->key_size << 1;
1292 } else {
1293 if (sz >= maxlen)
1294 return -ENOMEM;
1295 result[sz++] = '-';
1296 }
1297
1298 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
1299 cc->dev->name, (unsigned long long)cc->start);
1300 break;
1301 }
1302 return 0;
1303}
1304
1305static void crypt_postsuspend(struct dm_target *ti)
1306{
1307 struct crypt_config *cc = ti->private;
1308
1309 set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1310}
1311
1312static int crypt_preresume(struct dm_target *ti)
1313{
1314 struct crypt_config *cc = ti->private;
1315
1316 if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
1317 DMERR("aborting resume - crypt key is not set.");
1318 return -EAGAIN;
1319 }
1320
1321 return 0;
1322}
1323
1324static void crypt_resume(struct dm_target *ti)
1325{
1326 struct crypt_config *cc = ti->private;
1327
1328 clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1329}
1330
1331/* Message interface
1332 * key set <key>
1333 * key wipe
1334 */
1335static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1336{
1337 struct crypt_config *cc = ti->private;
1338 int ret = -EINVAL;
1339
1340 if (argc < 2)
1341 goto error;
1342
1343 if (!strnicmp(argv[0], MESG_STR("key"))) {
1344 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1345 DMWARN("not suspended during key manipulation.");
1346 return -EINVAL;
1347 }
1348 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set"))) {
1349 ret = crypt_set_key(cc, argv[2]);
1350 if (ret)
1351 return ret;
1352 if (cc->iv_gen_ops && cc->iv_gen_ops->init)
1353 ret = cc->iv_gen_ops->init(cc);
1354 return ret;
1355 }
1356 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe"))) {
1357 if (cc->iv_gen_ops && cc->iv_gen_ops->wipe) {
1358 ret = cc->iv_gen_ops->wipe(cc);
1359 if (ret)
1360 return ret;
1361 }
1362 return crypt_wipe_key(cc);
1363 }
1364 }
1365
1366error:
1367 DMWARN("unrecognised message received.");
1368 return -EINVAL;
1369}
1370
1371static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
1372 struct bio_vec *biovec, int max_size)
1373{
1374 struct crypt_config *cc = ti->private;
1375 struct request_queue *q = bdev_get_queue(cc->dev->bdev);
1376
1377 if (!q->merge_bvec_fn)
1378 return max_size;
1379
1380 bvm->bi_bdev = cc->dev->bdev;
1381 bvm->bi_sector = cc->start + bvm->bi_sector - ti->begin;
1382
1383 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
1384}
1385
1386static int crypt_iterate_devices(struct dm_target *ti,
1387 iterate_devices_callout_fn fn, void *data)
1388{
1389 struct crypt_config *cc = ti->private;
1390
1391 return fn(ti, cc->dev, cc->start, ti->len, data);
1392}
1393
1394static struct target_type crypt_target = {
1395 .name = "crypt",
1396 .version = {1, 7, 0},
1397 .module = THIS_MODULE,
1398 .ctr = crypt_ctr,
1399 .dtr = crypt_dtr,
1400 .map = crypt_map,
1401 .status = crypt_status,
1402 .postsuspend = crypt_postsuspend,
1403 .preresume = crypt_preresume,
1404 .resume = crypt_resume,
1405 .message = crypt_message,
1406 .merge = crypt_merge,
1407 .iterate_devices = crypt_iterate_devices,
1408};
1409
1410static int __init dm_crypt_init(void)
1411{
1412 int r;
1413
1414 _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
1415 if (!_crypt_io_pool)
1416 return -ENOMEM;
1417
1418 r = dm_register_target(&crypt_target);
1419 if (r < 0) {
1420 DMERR("register failed %d", r);
1421 kmem_cache_destroy(_crypt_io_pool);
1422 }
1423
1424 return r;
1425}
1426
1427static void __exit dm_crypt_exit(void)
1428{
1429 dm_unregister_target(&crypt_target);
1430 kmem_cache_destroy(_crypt_io_pool);
1431}
1432
1433module_init(dm_crypt_init);
1434module_exit(dm_crypt_exit);
1435
1436MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1437MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1438MODULE_LICENSE("GPL");