blob: cf6631056683b76cc3abbf2afa0a9564261de5f5 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
3 * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
4 *
5 * This file is released under the GPL.
6 */
7
8#include <linux/module.h>
9#include <linux/init.h>
10#include <linux/kernel.h>
11#include <linux/bio.h>
12#include <linux/blkdev.h>
13#include <linux/mempool.h>
14#include <linux/slab.h>
15#include <linux/crypto.h>
16#include <linux/workqueue.h>
17#include <asm/atomic.h>
David Hardeman378f0582005-09-17 17:55:31 +100018#include <linux/scatterlist.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <asm/page.h>
20
21#include "dm.h"
22
23#define PFX "crypt: "
24
25/*
26 * per bio private data
27 */
28struct crypt_io {
29 struct dm_target *target;
30 struct bio *bio;
31 struct bio *first_clone;
32 struct work_struct work;
33 atomic_t pending;
34 int error;
35};
36
37/*
38 * context holding the current state of a multi-part conversion
39 */
40struct convert_context {
41 struct bio *bio_in;
42 struct bio *bio_out;
43 unsigned int offset_in;
44 unsigned int offset_out;
45 unsigned int idx_in;
46 unsigned int idx_out;
47 sector_t sector;
48 int write;
49};
50
51struct crypt_config;
52
53struct crypt_iv_operations {
54 int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
55 const char *opts);
56 void (*dtr)(struct crypt_config *cc);
57 const char *(*status)(struct crypt_config *cc);
58 int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
59};
60
61/*
62 * Crypt: maps a linear range of a block device
63 * and encrypts / decrypts at the same time.
64 */
65struct crypt_config {
66 struct dm_dev *dev;
67 sector_t start;
68
69 /*
70 * pool for per bio private data and
71 * for encryption buffer pages
72 */
73 mempool_t *io_pool;
74 mempool_t *page_pool;
75
76 /*
77 * crypto related data
78 */
79 struct crypt_iv_operations *iv_gen_ops;
80 char *iv_mode;
81 void *iv_gen_private;
82 sector_t iv_offset;
83 unsigned int iv_size;
84
85 struct crypto_tfm *tfm;
86 unsigned int key_size;
87 u8 key[0];
88};
89
90#define MIN_IOS 256
91#define MIN_POOL_PAGES 32
92#define MIN_BIO_PAGES 8
93
94static kmem_cache_t *_crypt_io_pool;
95
96/*
97 * Mempool alloc and free functions for the page
98 */
Al Virodd0fc662005-10-07 07:46:04 +010099static void *mempool_alloc_page(gfp_t gfp_mask, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100{
101 return alloc_page(gfp_mask);
102}
103
104static void mempool_free_page(void *page, void *data)
105{
106 __free_page(page);
107}
108
109
110/*
111 * Different IV generation algorithms:
112 *
113 * plain: the initial vector is the 32-bit low-endian version of the sector
114 * number, padded with zeros if neccessary.
115 *
116 * ess_iv: "encrypted sector|salt initial vector", the sector number is
117 * encrypted with the bulk cipher using a salt as key. The salt
118 * should be derived from the bulk cipher's key via hashing.
119 *
120 * plumb: unimplemented, see:
121 * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
122 */
123
124static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
125{
126 memset(iv, 0, cc->iv_size);
127 *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
128
129 return 0;
130}
131
132static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
133 const char *opts)
134{
135 struct crypto_tfm *essiv_tfm;
136 struct crypto_tfm *hash_tfm;
137 struct scatterlist sg;
138 unsigned int saltsize;
139 u8 *salt;
140
141 if (opts == NULL) {
142 ti->error = PFX "Digest algorithm missing for ESSIV mode";
143 return -EINVAL;
144 }
145
146 /* Hash the cipher key with the given hash algorithm */
Herbert Xueb6f1162005-09-01 17:43:25 -0700147 hash_tfm = crypto_alloc_tfm(opts, CRYPTO_TFM_REQ_MAY_SLEEP);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 if (hash_tfm == NULL) {
149 ti->error = PFX "Error initializing ESSIV hash";
150 return -EINVAL;
151 }
152
153 if (crypto_tfm_alg_type(hash_tfm) != CRYPTO_ALG_TYPE_DIGEST) {
154 ti->error = PFX "Expected digest algorithm for ESSIV hash";
155 crypto_free_tfm(hash_tfm);
156 return -EINVAL;
157 }
158
159 saltsize = crypto_tfm_alg_digestsize(hash_tfm);
160 salt = kmalloc(saltsize, GFP_KERNEL);
161 if (salt == NULL) {
162 ti->error = PFX "Error kmallocing salt storage in ESSIV";
163 crypto_free_tfm(hash_tfm);
164 return -ENOMEM;
165 }
166
David Hardeman378f0582005-09-17 17:55:31 +1000167 sg_set_buf(&sg, cc->key, cc->key_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 crypto_digest_digest(hash_tfm, &sg, 1, salt);
169 crypto_free_tfm(hash_tfm);
170
171 /* Setup the essiv_tfm with the given salt */
172 essiv_tfm = crypto_alloc_tfm(crypto_tfm_alg_name(cc->tfm),
Herbert Xueb6f1162005-09-01 17:43:25 -0700173 CRYPTO_TFM_MODE_ECB |
174 CRYPTO_TFM_REQ_MAY_SLEEP);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 if (essiv_tfm == NULL) {
176 ti->error = PFX "Error allocating crypto tfm for ESSIV";
177 kfree(salt);
178 return -EINVAL;
179 }
180 if (crypto_tfm_alg_blocksize(essiv_tfm)
181 != crypto_tfm_alg_ivsize(cc->tfm)) {
182 ti->error = PFX "Block size of ESSIV cipher does "
183 "not match IV size of block cipher";
184 crypto_free_tfm(essiv_tfm);
185 kfree(salt);
186 return -EINVAL;
187 }
188 if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) {
189 ti->error = PFX "Failed to set key for ESSIV cipher";
190 crypto_free_tfm(essiv_tfm);
191 kfree(salt);
192 return -EINVAL;
193 }
194 kfree(salt);
195
196 cc->iv_gen_private = (void *)essiv_tfm;
197 return 0;
198}
199
200static void crypt_iv_essiv_dtr(struct crypt_config *cc)
201{
202 crypto_free_tfm((struct crypto_tfm *)cc->iv_gen_private);
203 cc->iv_gen_private = NULL;
204}
205
206static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
207{
David Hardeman378f0582005-09-17 17:55:31 +1000208 struct scatterlist sg;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209
210 memset(iv, 0, cc->iv_size);
211 *(u64 *)iv = cpu_to_le64(sector);
212
David Hardeman378f0582005-09-17 17:55:31 +1000213 sg_set_buf(&sg, iv, cc->iv_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 crypto_cipher_encrypt((struct crypto_tfm *)cc->iv_gen_private,
215 &sg, &sg, cc->iv_size);
216
217 return 0;
218}
219
220static struct crypt_iv_operations crypt_iv_plain_ops = {
221 .generator = crypt_iv_plain_gen
222};
223
224static struct crypt_iv_operations crypt_iv_essiv_ops = {
225 .ctr = crypt_iv_essiv_ctr,
226 .dtr = crypt_iv_essiv_dtr,
227 .generator = crypt_iv_essiv_gen
228};
229
230
231static inline int
232crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
233 struct scatterlist *in, unsigned int length,
234 int write, sector_t sector)
235{
236 u8 iv[cc->iv_size];
237 int r;
238
239 if (cc->iv_gen_ops) {
240 r = cc->iv_gen_ops->generator(cc, iv, sector);
241 if (r < 0)
242 return r;
243
244 if (write)
245 r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv);
246 else
247 r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv);
248 } else {
249 if (write)
250 r = crypto_cipher_encrypt(cc->tfm, out, in, length);
251 else
252 r = crypto_cipher_decrypt(cc->tfm, out, in, length);
253 }
254
255 return r;
256}
257
258static void
259crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
260 struct bio *bio_out, struct bio *bio_in,
261 sector_t sector, int write)
262{
263 ctx->bio_in = bio_in;
264 ctx->bio_out = bio_out;
265 ctx->offset_in = 0;
266 ctx->offset_out = 0;
267 ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
268 ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
269 ctx->sector = sector + cc->iv_offset;
270 ctx->write = write;
271}
272
273/*
274 * Encrypt / decrypt data from one bio to another one (can be the same one)
275 */
276static int crypt_convert(struct crypt_config *cc,
277 struct convert_context *ctx)
278{
279 int r = 0;
280
281 while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
282 ctx->idx_out < ctx->bio_out->bi_vcnt) {
283 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
284 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
285 struct scatterlist sg_in = {
286 .page = bv_in->bv_page,
287 .offset = bv_in->bv_offset + ctx->offset_in,
288 .length = 1 << SECTOR_SHIFT
289 };
290 struct scatterlist sg_out = {
291 .page = bv_out->bv_page,
292 .offset = bv_out->bv_offset + ctx->offset_out,
293 .length = 1 << SECTOR_SHIFT
294 };
295
296 ctx->offset_in += sg_in.length;
297 if (ctx->offset_in >= bv_in->bv_len) {
298 ctx->offset_in = 0;
299 ctx->idx_in++;
300 }
301
302 ctx->offset_out += sg_out.length;
303 if (ctx->offset_out >= bv_out->bv_len) {
304 ctx->offset_out = 0;
305 ctx->idx_out++;
306 }
307
308 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
309 ctx->write, ctx->sector);
310 if (r < 0)
311 break;
312
313 ctx->sector++;
314 }
315
316 return r;
317}
318
319/*
320 * Generate a new unfragmented bio with the given size
321 * This should never violate the device limitations
322 * May return a smaller bio when running out of pages
323 */
324static struct bio *
325crypt_alloc_buffer(struct crypt_config *cc, unsigned int size,
326 struct bio *base_bio, unsigned int *bio_vec_idx)
327{
328 struct bio *bio;
329 unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
Al Virob4e3ca12005-10-21 03:22:34 -0400330 gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 unsigned int i;
332
333 /*
Nick Pigginbd53b712005-05-01 08:58:37 -0700334 * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and
335 * to fail earlier. This is not necessary but increases throughput.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 * FIXME: Is this really intelligent?
337 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 if (base_bio)
Nick Pigginbd53b712005-05-01 08:58:37 -0700339 bio = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 else
Nick Pigginbd53b712005-05-01 08:58:37 -0700341 bio = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs);
342 if (!bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344
345 /* if the last bio was not complete, continue where that one ended */
346 bio->bi_idx = *bio_vec_idx;
347 bio->bi_vcnt = *bio_vec_idx;
348 bio->bi_size = 0;
349 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
350
351 /* bio->bi_idx pages have already been allocated */
352 size -= bio->bi_idx * PAGE_SIZE;
353
354 for(i = bio->bi_idx; i < nr_iovecs; i++) {
355 struct bio_vec *bv = bio_iovec_idx(bio, i);
356
357 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
358 if (!bv->bv_page)
359 break;
360
361 /*
362 * if additional pages cannot be allocated without waiting,
363 * return a partially allocated bio, the caller will then try
364 * to allocate additional bios while submitting this partial bio
365 */
366 if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1))
367 gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
368
369 bv->bv_offset = 0;
370 if (size > PAGE_SIZE)
371 bv->bv_len = PAGE_SIZE;
372 else
373 bv->bv_len = size;
374
375 bio->bi_size += bv->bv_len;
376 bio->bi_vcnt++;
377 size -= bv->bv_len;
378 }
379
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 if (!bio->bi_size) {
381 bio_put(bio);
382 return NULL;
383 }
384
385 /*
386 * Remember the last bio_vec allocated to be able
387 * to correctly continue after the splitting.
388 */
389 *bio_vec_idx = bio->bi_vcnt;
390
391 return bio;
392}
393
394static void crypt_free_buffer_pages(struct crypt_config *cc,
395 struct bio *bio, unsigned int bytes)
396{
397 unsigned int i, start, end;
398 struct bio_vec *bv;
399
400 /*
401 * This is ugly, but Jens Axboe thinks that using bi_idx in the
402 * endio function is too dangerous at the moment, so I calculate the
403 * correct position using bi_vcnt and bi_size.
404 * The bv_offset and bv_len fields might already be modified but we
405 * know that we always allocated whole pages.
406 * A fix to the bi_idx issue in the kernel is in the works, so
407 * we will hopefully be able to revert to the cleaner solution soon.
408 */
409 i = bio->bi_vcnt - 1;
410 bv = bio_iovec_idx(bio, i);
411 end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size;
412 start = end - bytes;
413
414 start >>= PAGE_SHIFT;
415 if (!bio->bi_size)
416 end = bio->bi_vcnt;
417 else
418 end >>= PAGE_SHIFT;
419
420 for(i = start; i < end; i++) {
421 bv = bio_iovec_idx(bio, i);
422 BUG_ON(!bv->bv_page);
423 mempool_free(bv->bv_page, cc->page_pool);
424 bv->bv_page = NULL;
425 }
426}
427
428/*
429 * One of the bios was finished. Check for completion of
430 * the whole request and correctly clean up the buffer.
431 */
432static void dec_pending(struct crypt_io *io, int error)
433{
434 struct crypt_config *cc = (struct crypt_config *) io->target->private;
435
436 if (error < 0)
437 io->error = error;
438
439 if (!atomic_dec_and_test(&io->pending))
440 return;
441
442 if (io->first_clone)
443 bio_put(io->first_clone);
444
445 bio_endio(io->bio, io->bio->bi_size, io->error);
446
447 mempool_free(io, cc->io_pool);
448}
449
450/*
451 * kcryptd:
452 *
453 * Needed because it would be very unwise to do decryption in an
454 * interrupt context, so bios returning from read requests get
455 * queued here.
456 */
457static struct workqueue_struct *_kcryptd_workqueue;
458
459static void kcryptd_do_work(void *data)
460{
461 struct crypt_io *io = (struct crypt_io *) data;
462 struct crypt_config *cc = (struct crypt_config *) io->target->private;
463 struct convert_context ctx;
464 int r;
465
466 crypt_convert_init(cc, &ctx, io->bio, io->bio,
467 io->bio->bi_sector - io->target->begin, 0);
468 r = crypt_convert(cc, &ctx);
469
470 dec_pending(io, r);
471}
472
473static void kcryptd_queue_io(struct crypt_io *io)
474{
475 INIT_WORK(&io->work, kcryptd_do_work, io);
476 queue_work(_kcryptd_workqueue, &io->work);
477}
478
479/*
480 * Decode key from its hex representation
481 */
482static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
483{
484 char buffer[3];
485 char *endp;
486 unsigned int i;
487
488 buffer[2] = '\0';
489
490 for(i = 0; i < size; i++) {
491 buffer[0] = *hex++;
492 buffer[1] = *hex++;
493
494 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
495
496 if (endp != &buffer[2])
497 return -EINVAL;
498 }
499
500 if (*hex != '\0')
501 return -EINVAL;
502
503 return 0;
504}
505
506/*
507 * Encode key into its hex representation
508 */
509static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
510{
511 unsigned int i;
512
513 for(i = 0; i < size; i++) {
514 sprintf(hex, "%02x", *key);
515 hex += 2;
516 key++;
517 }
518}
519
520/*
521 * Construct an encryption mapping:
522 * <cipher> <key> <iv_offset> <dev_path> <start>
523 */
524static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
525{
526 struct crypt_config *cc;
527 struct crypto_tfm *tfm;
528 char *tmp;
529 char *cipher;
530 char *chainmode;
531 char *ivmode;
532 char *ivopts;
533 unsigned int crypto_flags;
534 unsigned int key_size;
535
536 if (argc != 5) {
537 ti->error = PFX "Not enough arguments";
538 return -EINVAL;
539 }
540
541 tmp = argv[0];
542 cipher = strsep(&tmp, "-");
543 chainmode = strsep(&tmp, "-");
544 ivopts = strsep(&tmp, "-");
545 ivmode = strsep(&ivopts, ":");
546
547 if (tmp)
548 DMWARN(PFX "Unexpected additional cipher options");
549
550 key_size = strlen(argv[1]) >> 1;
551
552 cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
553 if (cc == NULL) {
554 ti->error =
555 PFX "Cannot allocate transparent encryption context";
556 return -ENOMEM;
557 }
558
559 cc->key_size = key_size;
560 if ((!key_size && strcmp(argv[1], "-") != 0) ||
561 (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) {
562 ti->error = PFX "Error decoding key";
563 goto bad1;
564 }
565
566 /* Compatiblity mode for old dm-crypt cipher strings */
567 if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
568 chainmode = "cbc";
569 ivmode = "plain";
570 }
571
572 /* Choose crypto_flags according to chainmode */
573 if (strcmp(chainmode, "cbc") == 0)
574 crypto_flags = CRYPTO_TFM_MODE_CBC;
575 else if (strcmp(chainmode, "ecb") == 0)
576 crypto_flags = CRYPTO_TFM_MODE_ECB;
577 else {
578 ti->error = PFX "Unknown chaining mode";
579 goto bad1;
580 }
581
582 if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) {
583 ti->error = PFX "This chaining mode requires an IV mechanism";
584 goto bad1;
585 }
586
Herbert Xueb6f1162005-09-01 17:43:25 -0700587 tfm = crypto_alloc_tfm(cipher, crypto_flags | CRYPTO_TFM_REQ_MAY_SLEEP);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588 if (!tfm) {
589 ti->error = PFX "Error allocating crypto tfm";
590 goto bad1;
591 }
592 if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) {
593 ti->error = PFX "Expected cipher algorithm";
594 goto bad2;
595 }
596
597 cc->tfm = tfm;
598
599 /*
600 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>".
601 * See comments at iv code
602 */
603
604 if (ivmode == NULL)
605 cc->iv_gen_ops = NULL;
606 else if (strcmp(ivmode, "plain") == 0)
607 cc->iv_gen_ops = &crypt_iv_plain_ops;
608 else if (strcmp(ivmode, "essiv") == 0)
609 cc->iv_gen_ops = &crypt_iv_essiv_ops;
610 else {
611 ti->error = PFX "Invalid IV mode";
612 goto bad2;
613 }
614
615 if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
616 cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
617 goto bad2;
618
619 if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv)
620 /* at least a 64 bit sector number should fit in our buffer */
621 cc->iv_size = max(crypto_tfm_alg_ivsize(tfm),
622 (unsigned int)(sizeof(u64) / sizeof(u8)));
623 else {
624 cc->iv_size = 0;
625 if (cc->iv_gen_ops) {
626 DMWARN(PFX "Selected cipher does not support IVs");
627 if (cc->iv_gen_ops->dtr)
628 cc->iv_gen_ops->dtr(cc);
629 cc->iv_gen_ops = NULL;
630 }
631 }
632
633 cc->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
634 mempool_free_slab, _crypt_io_pool);
635 if (!cc->io_pool) {
636 ti->error = PFX "Cannot allocate crypt io mempool";
637 goto bad3;
638 }
639
640 cc->page_pool = mempool_create(MIN_POOL_PAGES, mempool_alloc_page,
641 mempool_free_page, NULL);
642 if (!cc->page_pool) {
643 ti->error = PFX "Cannot allocate page mempool";
644 goto bad4;
645 }
646
647 if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) {
648 ti->error = PFX "Error setting key";
649 goto bad5;
650 }
651
652 if (sscanf(argv[2], SECTOR_FORMAT, &cc->iv_offset) != 1) {
653 ti->error = PFX "Invalid iv_offset sector";
654 goto bad5;
655 }
656
657 if (sscanf(argv[4], SECTOR_FORMAT, &cc->start) != 1) {
658 ti->error = PFX "Invalid device sector";
659 goto bad5;
660 }
661
662 if (dm_get_device(ti, argv[3], cc->start, ti->len,
663 dm_table_get_mode(ti->table), &cc->dev)) {
664 ti->error = PFX "Device lookup failed";
665 goto bad5;
666 }
667
668 if (ivmode && cc->iv_gen_ops) {
669 if (ivopts)
670 *(ivopts - 1) = ':';
671 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
672 if (!cc->iv_mode) {
673 ti->error = PFX "Error kmallocing iv_mode string";
674 goto bad5;
675 }
676 strcpy(cc->iv_mode, ivmode);
677 } else
678 cc->iv_mode = NULL;
679
680 ti->private = cc;
681 return 0;
682
683bad5:
684 mempool_destroy(cc->page_pool);
685bad4:
686 mempool_destroy(cc->io_pool);
687bad3:
688 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
689 cc->iv_gen_ops->dtr(cc);
690bad2:
691 crypto_free_tfm(tfm);
692bad1:
693 kfree(cc);
694 return -EINVAL;
695}
696
697static void crypt_dtr(struct dm_target *ti)
698{
699 struct crypt_config *cc = (struct crypt_config *) ti->private;
700
701 mempool_destroy(cc->page_pool);
702 mempool_destroy(cc->io_pool);
703
Jesper Juhl990a8ba2005-06-21 17:17:30 -0700704 kfree(cc->iv_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
706 cc->iv_gen_ops->dtr(cc);
707 crypto_free_tfm(cc->tfm);
708 dm_put_device(ti, cc->dev);
709 kfree(cc);
710}
711
712static int crypt_endio(struct bio *bio, unsigned int done, int error)
713{
714 struct crypt_io *io = (struct crypt_io *) bio->bi_private;
715 struct crypt_config *cc = (struct crypt_config *) io->target->private;
716
717 if (bio_data_dir(bio) == WRITE) {
718 /*
719 * free the processed pages, even if
720 * it's only a partially completed write
721 */
722 crypt_free_buffer_pages(cc, bio, done);
723 }
724
725 if (bio->bi_size)
726 return 1;
727
728 bio_put(bio);
729
730 /*
731 * successful reads are decrypted by the worker thread
732 */
733 if ((bio_data_dir(bio) == READ)
734 && bio_flagged(bio, BIO_UPTODATE)) {
735 kcryptd_queue_io(io);
736 return 0;
737 }
738
739 dec_pending(io, error);
740 return error;
741}
742
743static inline struct bio *
744crypt_clone(struct crypt_config *cc, struct crypt_io *io, struct bio *bio,
745 sector_t sector, unsigned int *bvec_idx,
746 struct convert_context *ctx)
747{
748 struct bio *clone;
749
750 if (bio_data_dir(bio) == WRITE) {
751 clone = crypt_alloc_buffer(cc, bio->bi_size,
752 io->first_clone, bvec_idx);
753 if (clone) {
754 ctx->bio_out = clone;
755 if (crypt_convert(cc, ctx) < 0) {
756 crypt_free_buffer_pages(cc, clone,
757 clone->bi_size);
758 bio_put(clone);
759 return NULL;
760 }
761 }
762 } else {
763 /*
764 * The block layer might modify the bvec array, so always
765 * copy the required bvecs because we need the original
766 * one in order to decrypt the whole bio data *afterwards*.
767 */
768 clone = bio_alloc(GFP_NOIO, bio_segments(bio));
769 if (clone) {
770 clone->bi_idx = 0;
771 clone->bi_vcnt = bio_segments(bio);
772 clone->bi_size = bio->bi_size;
773 memcpy(clone->bi_io_vec, bio_iovec(bio),
774 sizeof(struct bio_vec) * clone->bi_vcnt);
775 }
776 }
777
778 if (!clone)
779 return NULL;
780
781 clone->bi_private = io;
782 clone->bi_end_io = crypt_endio;
783 clone->bi_bdev = cc->dev->bdev;
784 clone->bi_sector = cc->start + sector;
785 clone->bi_rw = bio->bi_rw;
786
787 return clone;
788}
789
790static int crypt_map(struct dm_target *ti, struct bio *bio,
791 union map_info *map_context)
792{
793 struct crypt_config *cc = (struct crypt_config *) ti->private;
794 struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO);
795 struct convert_context ctx;
796 struct bio *clone;
797 unsigned int remaining = bio->bi_size;
798 sector_t sector = bio->bi_sector - ti->begin;
799 unsigned int bvec_idx = 0;
800
801 io->target = ti;
802 io->bio = bio;
803 io->first_clone = NULL;
804 io->error = 0;
805 atomic_set(&io->pending, 1); /* hold a reference */
806
807 if (bio_data_dir(bio) == WRITE)
808 crypt_convert_init(cc, &ctx, NULL, bio, sector, 1);
809
810 /*
811 * The allocated buffers can be smaller than the whole bio,
812 * so repeat the whole process until all the data can be handled.
813 */
814 while (remaining) {
815 clone = crypt_clone(cc, io, bio, sector, &bvec_idx, &ctx);
816 if (!clone)
817 goto cleanup;
818
819 if (!io->first_clone) {
820 /*
821 * hold a reference to the first clone, because it
822 * holds the bio_vec array and that can't be freed
823 * before all other clones are released
824 */
825 bio_get(clone);
826 io->first_clone = clone;
827 }
828 atomic_inc(&io->pending);
829
830 remaining -= clone->bi_size;
831 sector += bio_sectors(clone);
832
833 generic_make_request(clone);
834
835 /* out of memory -> run queues */
836 if (remaining)
837 blk_congestion_wait(bio_data_dir(clone), HZ/100);
838 }
839
840 /* drop reference, clones could have returned before we reach this */
841 dec_pending(io, 0);
842 return 0;
843
844cleanup:
845 if (io->first_clone) {
846 dec_pending(io, -ENOMEM);
847 return 0;
848 }
849
850 /* if no bio has been dispatched yet, we can directly return the error */
851 mempool_free(io, cc->io_pool);
852 return -ENOMEM;
853}
854
855static int crypt_status(struct dm_target *ti, status_type_t type,
856 char *result, unsigned int maxlen)
857{
858 struct crypt_config *cc = (struct crypt_config *) ti->private;
859 const char *cipher;
860 const char *chainmode = NULL;
861 unsigned int sz = 0;
862
863 switch (type) {
864 case STATUSTYPE_INFO:
865 result[0] = '\0';
866 break;
867
868 case STATUSTYPE_TABLE:
869 cipher = crypto_tfm_alg_name(cc->tfm);
870
871 switch(cc->tfm->crt_cipher.cit_mode) {
872 case CRYPTO_TFM_MODE_CBC:
873 chainmode = "cbc";
874 break;
875 case CRYPTO_TFM_MODE_ECB:
876 chainmode = "ecb";
877 break;
878 default:
879 BUG();
880 }
881
882 if (cc->iv_mode)
883 DMEMIT("%s-%s-%s ", cipher, chainmode, cc->iv_mode);
884 else
885 DMEMIT("%s-%s ", cipher, chainmode);
886
887 if (cc->key_size > 0) {
888 if ((maxlen - sz) < ((cc->key_size << 1) + 1))
889 return -ENOMEM;
890
891 crypt_encode_key(result + sz, cc->key, cc->key_size);
892 sz += cc->key_size << 1;
893 } else {
894 if (sz >= maxlen)
895 return -ENOMEM;
896 result[sz++] = '-';
897 }
898
899 DMEMIT(" " SECTOR_FORMAT " %s " SECTOR_FORMAT,
900 cc->iv_offset, cc->dev->name, cc->start);
901 break;
902 }
903 return 0;
904}
905
906static struct target_type crypt_target = {
907 .name = "crypt",
908 .version= {1, 1, 0},
909 .module = THIS_MODULE,
910 .ctr = crypt_ctr,
911 .dtr = crypt_dtr,
912 .map = crypt_map,
913 .status = crypt_status,
914};
915
916static int __init dm_crypt_init(void)
917{
918 int r;
919
920 _crypt_io_pool = kmem_cache_create("dm-crypt_io",
921 sizeof(struct crypt_io),
922 0, 0, NULL, NULL);
923 if (!_crypt_io_pool)
924 return -ENOMEM;
925
926 _kcryptd_workqueue = create_workqueue("kcryptd");
927 if (!_kcryptd_workqueue) {
928 r = -ENOMEM;
929 DMERR(PFX "couldn't create kcryptd");
930 goto bad1;
931 }
932
933 r = dm_register_target(&crypt_target);
934 if (r < 0) {
935 DMERR(PFX "register failed %d", r);
936 goto bad2;
937 }
938
939 return 0;
940
941bad2:
942 destroy_workqueue(_kcryptd_workqueue);
943bad1:
944 kmem_cache_destroy(_crypt_io_pool);
945 return r;
946}
947
948static void __exit dm_crypt_exit(void)
949{
950 int r = dm_unregister_target(&crypt_target);
951
952 if (r < 0)
953 DMERR(PFX "unregister failed %d", r);
954
955 destroy_workqueue(_kcryptd_workqueue);
956 kmem_cache_destroy(_crypt_io_pool);
957}
958
959module_init(dm_crypt_init);
960module_exit(dm_crypt_exit);
961
962MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
963MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
964MODULE_LICENSE("GPL");