xref: /openbmc/linux/drivers/md/dm-crypt.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
3  * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
4  * Copyright (C) 2006 Red Hat, Inc. All rights reserved.
5  *
6  * This file is released under the GPL.
7  */
8 
9 #include <linux/err.h>
10 #include <linux/module.h>
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/bio.h>
14 #include <linux/blkdev.h>
15 #include <linux/mempool.h>
16 #include <linux/slab.h>
17 #include <linux/crypto.h>
18 #include <linux/workqueue.h>
19 #include <linux/backing-dev.h>
20 #include <asm/atomic.h>
21 #include <linux/scatterlist.h>
22 #include <asm/page.h>
23 #include <asm/unaligned.h>
24 
25 #include "dm.h"
26 
27 #define DM_MSG_PREFIX "crypt"
28 #define MESG_STR(x) x, sizeof(x)
29 
30 /*
31  * per bio private data
32  */
33 struct crypt_io {
34 	struct dm_target *target;
35 	struct bio *base_bio;
36 	struct work_struct work;
37 	atomic_t pending;
38 	int error;
39 	int post_process;
40 };
41 
42 /*
43  * context holding the current state of a multi-part conversion
44  */
45 struct convert_context {
46 	struct bio *bio_in;
47 	struct bio *bio_out;
48 	unsigned int offset_in;
49 	unsigned int offset_out;
50 	unsigned int idx_in;
51 	unsigned int idx_out;
52 	sector_t sector;
53 	int write;
54 };
55 
56 struct crypt_config;
57 
58 struct crypt_iv_operations {
59 	int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
60 	           const char *opts);
61 	void (*dtr)(struct crypt_config *cc);
62 	const char *(*status)(struct crypt_config *cc);
63 	int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
64 };
65 
66 /*
67  * Crypt: maps a linear range of a block device
68  * and encrypts / decrypts at the same time.
69  */
70 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
71 struct crypt_config {
72 	struct dm_dev *dev;
73 	sector_t start;
74 
75 	/*
76 	 * pool for per bio private data and
77 	 * for encryption buffer pages
78 	 */
79 	mempool_t *io_pool;
80 	mempool_t *page_pool;
81 	struct bio_set *bs;
82 
83 	/*
84 	 * crypto related data
85 	 */
86 	struct crypt_iv_operations *iv_gen_ops;
87 	char *iv_mode;
88 	union {
89 		struct crypto_cipher *essiv_tfm;
90 		int benbi_shift;
91 	} iv_gen_private;
92 	sector_t iv_offset;
93 	unsigned int iv_size;
94 
95 	char cipher[CRYPTO_MAX_ALG_NAME];
96 	char chainmode[CRYPTO_MAX_ALG_NAME];
97 	struct crypto_blkcipher *tfm;
98 	unsigned long flags;
99 	unsigned int key_size;
100 	u8 key[0];
101 };
102 
103 #define MIN_IOS        16
104 #define MIN_POOL_PAGES 32
105 #define MIN_BIO_PAGES  8
106 
107 static struct kmem_cache *_crypt_io_pool;
108 
109 static void clone_init(struct crypt_io *, struct bio *);
110 
111 /*
112  * Different IV generation algorithms:
113  *
114  * plain: the initial vector is the 32-bit little-endian version of the sector
115  *        number, padded with zeros if neccessary.
116  *
117  * essiv: "encrypted sector|salt initial vector", the sector number is
118  *        encrypted with the bulk cipher using a salt as key. The salt
119  *        should be derived from the bulk cipher's key via hashing.
120  *
121  * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
122  *        (needed for LRW-32-AES and possible other narrow block modes)
123  *
124  * null: the initial vector is always zero.  Provides compatibility with
125  *       obsolete loop_fish2 devices.  Do not use for new devices.
126  *
127  * plumb: unimplemented, see:
128  * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
129  */
130 
131 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
132 {
133 	memset(iv, 0, cc->iv_size);
134 	*(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
135 
136 	return 0;
137 }
138 
139 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
140 	                      const char *opts)
141 {
142 	struct crypto_cipher *essiv_tfm;
143 	struct crypto_hash *hash_tfm;
144 	struct hash_desc desc;
145 	struct scatterlist sg;
146 	unsigned int saltsize;
147 	u8 *salt;
148 	int err;
149 
150 	if (opts == NULL) {
151 		ti->error = "Digest algorithm missing for ESSIV mode";
152 		return -EINVAL;
153 	}
154 
155 	/* Hash the cipher key with the given hash algorithm */
156 	hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
157 	if (IS_ERR(hash_tfm)) {
158 		ti->error = "Error initializing ESSIV hash";
159 		return PTR_ERR(hash_tfm);
160 	}
161 
162 	saltsize = crypto_hash_digestsize(hash_tfm);
163 	salt = kmalloc(saltsize, GFP_KERNEL);
164 	if (salt == NULL) {
165 		ti->error = "Error kmallocing salt storage in ESSIV";
166 		crypto_free_hash(hash_tfm);
167 		return -ENOMEM;
168 	}
169 
170 	sg_set_buf(&sg, cc->key, cc->key_size);
171 	desc.tfm = hash_tfm;
172 	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
173 	err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
174 	crypto_free_hash(hash_tfm);
175 
176 	if (err) {
177 		ti->error = "Error calculating hash in ESSIV";
178 		return err;
179 	}
180 
181 	/* Setup the essiv_tfm with the given salt */
182 	essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
183 	if (IS_ERR(essiv_tfm)) {
184 		ti->error = "Error allocating crypto tfm for ESSIV";
185 		kfree(salt);
186 		return PTR_ERR(essiv_tfm);
187 	}
188 	if (crypto_cipher_blocksize(essiv_tfm) !=
189 	    crypto_blkcipher_ivsize(cc->tfm)) {
190 		ti->error = "Block size of ESSIV cipher does "
191 			        "not match IV size of block cipher";
192 		crypto_free_cipher(essiv_tfm);
193 		kfree(salt);
194 		return -EINVAL;
195 	}
196 	err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
197 	if (err) {
198 		ti->error = "Failed to set key for ESSIV cipher";
199 		crypto_free_cipher(essiv_tfm);
200 		kfree(salt);
201 		return err;
202 	}
203 	kfree(salt);
204 
205 	cc->iv_gen_private.essiv_tfm = essiv_tfm;
206 	return 0;
207 }
208 
209 static void crypt_iv_essiv_dtr(struct crypt_config *cc)
210 {
211 	crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
212 	cc->iv_gen_private.essiv_tfm = NULL;
213 }
214 
215 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
216 {
217 	memset(iv, 0, cc->iv_size);
218 	*(u64 *)iv = cpu_to_le64(sector);
219 	crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
220 	return 0;
221 }
222 
223 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
224 			      const char *opts)
225 {
226 	unsigned int bs = crypto_blkcipher_blocksize(cc->tfm);
227 	int log = ilog2(bs);
228 
229 	/* we need to calculate how far we must shift the sector count
230 	 * to get the cipher block count, we use this shift in _gen */
231 
232 	if (1 << log != bs) {
233 		ti->error = "cypher blocksize is not a power of 2";
234 		return -EINVAL;
235 	}
236 
237 	if (log > 9) {
238 		ti->error = "cypher blocksize is > 512";
239 		return -EINVAL;
240 	}
241 
242 	cc->iv_gen_private.benbi_shift = 9 - log;
243 
244 	return 0;
245 }
246 
247 static void crypt_iv_benbi_dtr(struct crypt_config *cc)
248 {
249 }
250 
251 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
252 {
253 	__be64 val;
254 
255 	memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
256 
257 	val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
258 	put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
259 
260 	return 0;
261 }
262 
263 static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
264 {
265 	memset(iv, 0, cc->iv_size);
266 
267 	return 0;
268 }
269 
270 static struct crypt_iv_operations crypt_iv_plain_ops = {
271 	.generator = crypt_iv_plain_gen
272 };
273 
274 static struct crypt_iv_operations crypt_iv_essiv_ops = {
275 	.ctr       = crypt_iv_essiv_ctr,
276 	.dtr       = crypt_iv_essiv_dtr,
277 	.generator = crypt_iv_essiv_gen
278 };
279 
280 static struct crypt_iv_operations crypt_iv_benbi_ops = {
281 	.ctr	   = crypt_iv_benbi_ctr,
282 	.dtr	   = crypt_iv_benbi_dtr,
283 	.generator = crypt_iv_benbi_gen
284 };
285 
286 static struct crypt_iv_operations crypt_iv_null_ops = {
287 	.generator = crypt_iv_null_gen
288 };
289 
290 static int
291 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
292                           struct scatterlist *in, unsigned int length,
293                           int write, sector_t sector)
294 {
295 	u8 iv[cc->iv_size] __attribute__ ((aligned(__alignof__(u64))));
296 	struct blkcipher_desc desc = {
297 		.tfm = cc->tfm,
298 		.info = iv,
299 		.flags = CRYPTO_TFM_REQ_MAY_SLEEP,
300 	};
301 	int r;
302 
303 	if (cc->iv_gen_ops) {
304 		r = cc->iv_gen_ops->generator(cc, iv, sector);
305 		if (r < 0)
306 			return r;
307 
308 		if (write)
309 			r = crypto_blkcipher_encrypt_iv(&desc, out, in, length);
310 		else
311 			r = crypto_blkcipher_decrypt_iv(&desc, out, in, length);
312 	} else {
313 		if (write)
314 			r = crypto_blkcipher_encrypt(&desc, out, in, length);
315 		else
316 			r = crypto_blkcipher_decrypt(&desc, out, in, length);
317 	}
318 
319 	return r;
320 }
321 
322 static void
323 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
324                    struct bio *bio_out, struct bio *bio_in,
325                    sector_t sector, int write)
326 {
327 	ctx->bio_in = bio_in;
328 	ctx->bio_out = bio_out;
329 	ctx->offset_in = 0;
330 	ctx->offset_out = 0;
331 	ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
332 	ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
333 	ctx->sector = sector + cc->iv_offset;
334 	ctx->write = write;
335 }
336 
337 /*
338  * Encrypt / decrypt data from one bio to another one (can be the same one)
339  */
340 static int crypt_convert(struct crypt_config *cc,
341                          struct convert_context *ctx)
342 {
343 	int r = 0;
344 
345 	while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
346 	      ctx->idx_out < ctx->bio_out->bi_vcnt) {
347 		struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
348 		struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
349 		struct scatterlist sg_in = {
350 			.page = bv_in->bv_page,
351 			.offset = bv_in->bv_offset + ctx->offset_in,
352 			.length = 1 << SECTOR_SHIFT
353 		};
354 		struct scatterlist sg_out = {
355 			.page = bv_out->bv_page,
356 			.offset = bv_out->bv_offset + ctx->offset_out,
357 			.length = 1 << SECTOR_SHIFT
358 		};
359 
360 		ctx->offset_in += sg_in.length;
361 		if (ctx->offset_in >= bv_in->bv_len) {
362 			ctx->offset_in = 0;
363 			ctx->idx_in++;
364 		}
365 
366 		ctx->offset_out += sg_out.length;
367 		if (ctx->offset_out >= bv_out->bv_len) {
368 			ctx->offset_out = 0;
369 			ctx->idx_out++;
370 		}
371 
372 		r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
373 		                              ctx->write, ctx->sector);
374 		if (r < 0)
375 			break;
376 
377 		ctx->sector++;
378 	}
379 
380 	return r;
381 }
382 
383  static void dm_crypt_bio_destructor(struct bio *bio)
384  {
385 	struct crypt_io *io = bio->bi_private;
386 	struct crypt_config *cc = io->target->private;
387 
388 	bio_free(bio, cc->bs);
389  }
390 
391 /*
392  * Generate a new unfragmented bio with the given size
393  * This should never violate the device limitations
394  * May return a smaller bio when running out of pages
395  */
396 static struct bio *crypt_alloc_buffer(struct crypt_io *io, unsigned int size)
397 {
398 	struct crypt_config *cc = io->target->private;
399 	struct bio *clone;
400 	unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
401 	gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
402 	unsigned int i;
403 
404 	clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
405 	if (!clone)
406 		return NULL;
407 
408 	clone_init(io, clone);
409 
410 	for (i = 0; i < nr_iovecs; i++) {
411 		struct bio_vec *bv = bio_iovec_idx(clone, i);
412 
413 		bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
414 		if (!bv->bv_page)
415 			break;
416 
417 		/*
418 		 * if additional pages cannot be allocated without waiting,
419 		 * return a partially allocated bio, the caller will then try
420 		 * to allocate additional bios while submitting this partial bio
421 		 */
422 		if (i == (MIN_BIO_PAGES - 1))
423 			gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
424 
425 		bv->bv_offset = 0;
426 		if (size > PAGE_SIZE)
427 			bv->bv_len = PAGE_SIZE;
428 		else
429 			bv->bv_len = size;
430 
431 		clone->bi_size += bv->bv_len;
432 		clone->bi_vcnt++;
433 		size -= bv->bv_len;
434 	}
435 
436 	if (!clone->bi_size) {
437 		bio_put(clone);
438 		return NULL;
439 	}
440 
441 	return clone;
442 }
443 
444 static void crypt_free_buffer_pages(struct crypt_config *cc,
445                                     struct bio *clone, unsigned int bytes)
446 {
447 	unsigned int i, start, end;
448 	struct bio_vec *bv;
449 
450 	/*
451 	 * This is ugly, but Jens Axboe thinks that using bi_idx in the
452 	 * endio function is too dangerous at the moment, so I calculate the
453 	 * correct position using bi_vcnt and bi_size.
454 	 * The bv_offset and bv_len fields might already be modified but we
455 	 * know that we always allocated whole pages.
456 	 * A fix to the bi_idx issue in the kernel is in the works, so
457 	 * we will hopefully be able to revert to the cleaner solution soon.
458 	 */
459 	i = clone->bi_vcnt - 1;
460 	bv = bio_iovec_idx(clone, i);
461 	end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - clone->bi_size;
462 	start = end - bytes;
463 
464 	start >>= PAGE_SHIFT;
465 	if (!clone->bi_size)
466 		end = clone->bi_vcnt;
467 	else
468 		end >>= PAGE_SHIFT;
469 
470 	for (i = start; i < end; i++) {
471 		bv = bio_iovec_idx(clone, i);
472 		BUG_ON(!bv->bv_page);
473 		mempool_free(bv->bv_page, cc->page_pool);
474 		bv->bv_page = NULL;
475 	}
476 }
477 
478 /*
479  * One of the bios was finished. Check for completion of
480  * the whole request and correctly clean up the buffer.
481  */
482 static void dec_pending(struct crypt_io *io, int error)
483 {
484 	struct crypt_config *cc = (struct crypt_config *) io->target->private;
485 
486 	if (error < 0)
487 		io->error = error;
488 
489 	if (!atomic_dec_and_test(&io->pending))
490 		return;
491 
492 	bio_endio(io->base_bio, io->base_bio->bi_size, io->error);
493 
494 	mempool_free(io, cc->io_pool);
495 }
496 
497 /*
498  * kcryptd:
499  *
500  * Needed because it would be very unwise to do decryption in an
501  * interrupt context.
502  */
503 static struct workqueue_struct *_kcryptd_workqueue;
504 static void kcryptd_do_work(struct work_struct *work);
505 
506 static void kcryptd_queue_io(struct crypt_io *io)
507 {
508 	INIT_WORK(&io->work, kcryptd_do_work);
509 	queue_work(_kcryptd_workqueue, &io->work);
510 }
511 
512 static int crypt_endio(struct bio *clone, unsigned int done, int error)
513 {
514 	struct crypt_io *io = clone->bi_private;
515 	struct crypt_config *cc = io->target->private;
516 	unsigned read_io = bio_data_dir(clone) == READ;
517 
518 	/*
519 	 * free the processed pages, even if
520 	 * it's only a partially completed write
521 	 */
522 	if (!read_io)
523 		crypt_free_buffer_pages(cc, clone, done);
524 
525 	/* keep going - not finished yet */
526 	if (unlikely(clone->bi_size))
527 		return 1;
528 
529 	if (!read_io)
530 		goto out;
531 
532 	if (unlikely(!bio_flagged(clone, BIO_UPTODATE))) {
533 		error = -EIO;
534 		goto out;
535 	}
536 
537 	bio_put(clone);
538 	io->post_process = 1;
539 	kcryptd_queue_io(io);
540 	return 0;
541 
542 out:
543 	bio_put(clone);
544 	dec_pending(io, error);
545 	return error;
546 }
547 
548 static void clone_init(struct crypt_io *io, struct bio *clone)
549 {
550 	struct crypt_config *cc = io->target->private;
551 
552 	clone->bi_private = io;
553 	clone->bi_end_io  = crypt_endio;
554 	clone->bi_bdev    = cc->dev->bdev;
555 	clone->bi_rw      = io->base_bio->bi_rw;
556 	clone->bi_destructor = dm_crypt_bio_destructor;
557 }
558 
559 static void process_read(struct crypt_io *io)
560 {
561 	struct crypt_config *cc = io->target->private;
562 	struct bio *base_bio = io->base_bio;
563 	struct bio *clone;
564 	sector_t sector = base_bio->bi_sector - io->target->begin;
565 
566 	atomic_inc(&io->pending);
567 
568 	/*
569 	 * The block layer might modify the bvec array, so always
570 	 * copy the required bvecs because we need the original
571 	 * one in order to decrypt the whole bio data *afterwards*.
572 	 */
573 	clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
574 	if (unlikely(!clone)) {
575 		dec_pending(io, -ENOMEM);
576 		return;
577 	}
578 
579 	clone_init(io, clone);
580 	clone->bi_idx = 0;
581 	clone->bi_vcnt = bio_segments(base_bio);
582 	clone->bi_size = base_bio->bi_size;
583 	clone->bi_sector = cc->start + sector;
584 	memcpy(clone->bi_io_vec, bio_iovec(base_bio),
585 	       sizeof(struct bio_vec) * clone->bi_vcnt);
586 
587 	generic_make_request(clone);
588 }
589 
590 static void process_write(struct crypt_io *io)
591 {
592 	struct crypt_config *cc = io->target->private;
593 	struct bio *base_bio = io->base_bio;
594 	struct bio *clone;
595 	struct convert_context ctx;
596 	unsigned remaining = base_bio->bi_size;
597 	sector_t sector = base_bio->bi_sector - io->target->begin;
598 
599 	atomic_inc(&io->pending);
600 
601 	crypt_convert_init(cc, &ctx, NULL, base_bio, sector, 1);
602 
603 	/*
604 	 * The allocated buffers can be smaller than the whole bio,
605 	 * so repeat the whole process until all the data can be handled.
606 	 */
607 	while (remaining) {
608 		clone = crypt_alloc_buffer(io, remaining);
609 		if (unlikely(!clone)) {
610 			dec_pending(io, -ENOMEM);
611 			return;
612 		}
613 
614 		ctx.bio_out = clone;
615 		ctx.idx_out = 0;
616 
617 		if (unlikely(crypt_convert(cc, &ctx) < 0)) {
618 			crypt_free_buffer_pages(cc, clone, clone->bi_size);
619 			bio_put(clone);
620 			dec_pending(io, -EIO);
621 			return;
622 		}
623 
624 		/* crypt_convert should have filled the clone bio */
625 		BUG_ON(ctx.idx_out < clone->bi_vcnt);
626 
627 		clone->bi_sector = cc->start + sector;
628 		remaining -= clone->bi_size;
629 		sector += bio_sectors(clone);
630 
631 		/* Grab another reference to the io struct
632 		 * before we kick off the request */
633 		if (remaining)
634 			atomic_inc(&io->pending);
635 
636 		generic_make_request(clone);
637 
638 		/* Do not reference clone after this - it
639 		 * may be gone already. */
640 
641 		/* out of memory -> run queues */
642 		if (remaining)
643 			congestion_wait(WRITE, HZ/100);
644 	}
645 }
646 
647 static void process_read_endio(struct crypt_io *io)
648 {
649 	struct crypt_config *cc = io->target->private;
650 	struct convert_context ctx;
651 
652 	crypt_convert_init(cc, &ctx, io->base_bio, io->base_bio,
653 			   io->base_bio->bi_sector - io->target->begin, 0);
654 
655 	dec_pending(io, crypt_convert(cc, &ctx));
656 }
657 
658 static void kcryptd_do_work(struct work_struct *work)
659 {
660 	struct crypt_io *io = container_of(work, struct crypt_io, work);
661 
662 	if (io->post_process)
663 		process_read_endio(io);
664 	else if (bio_data_dir(io->base_bio) == READ)
665 		process_read(io);
666 	else
667 		process_write(io);
668 }
669 
670 /*
671  * Decode key from its hex representation
672  */
673 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
674 {
675 	char buffer[3];
676 	char *endp;
677 	unsigned int i;
678 
679 	buffer[2] = '\0';
680 
681 	for (i = 0; i < size; i++) {
682 		buffer[0] = *hex++;
683 		buffer[1] = *hex++;
684 
685 		key[i] = (u8)simple_strtoul(buffer, &endp, 16);
686 
687 		if (endp != &buffer[2])
688 			return -EINVAL;
689 	}
690 
691 	if (*hex != '\0')
692 		return -EINVAL;
693 
694 	return 0;
695 }
696 
697 /*
698  * Encode key into its hex representation
699  */
700 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
701 {
702 	unsigned int i;
703 
704 	for (i = 0; i < size; i++) {
705 		sprintf(hex, "%02x", *key);
706 		hex += 2;
707 		key++;
708 	}
709 }
710 
711 static int crypt_set_key(struct crypt_config *cc, char *key)
712 {
713 	unsigned key_size = strlen(key) >> 1;
714 
715 	if (cc->key_size && cc->key_size != key_size)
716 		return -EINVAL;
717 
718 	cc->key_size = key_size; /* initial settings */
719 
720 	if ((!key_size && strcmp(key, "-")) ||
721 	    (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
722 		return -EINVAL;
723 
724 	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
725 
726 	return 0;
727 }
728 
729 static int crypt_wipe_key(struct crypt_config *cc)
730 {
731 	clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
732 	memset(&cc->key, 0, cc->key_size * sizeof(u8));
733 	return 0;
734 }
735 
736 /*
737  * Construct an encryption mapping:
738  * <cipher> <key> <iv_offset> <dev_path> <start>
739  */
740 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
741 {
742 	struct crypt_config *cc;
743 	struct crypto_blkcipher *tfm;
744 	char *tmp;
745 	char *cipher;
746 	char *chainmode;
747 	char *ivmode;
748 	char *ivopts;
749 	unsigned int key_size;
750 	unsigned long long tmpll;
751 
752 	if (argc != 5) {
753 		ti->error = "Not enough arguments";
754 		return -EINVAL;
755 	}
756 
757 	tmp = argv[0];
758 	cipher = strsep(&tmp, "-");
759 	chainmode = strsep(&tmp, "-");
760 	ivopts = strsep(&tmp, "-");
761 	ivmode = strsep(&ivopts, ":");
762 
763 	if (tmp)
764 		DMWARN("Unexpected additional cipher options");
765 
766 	key_size = strlen(argv[1]) >> 1;
767 
768  	cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
769 	if (cc == NULL) {
770 		ti->error =
771 			"Cannot allocate transparent encryption context";
772 		return -ENOMEM;
773 	}
774 
775  	if (crypt_set_key(cc, argv[1])) {
776 		ti->error = "Error decoding key";
777 		goto bad1;
778 	}
779 
780 	/* Compatiblity mode for old dm-crypt cipher strings */
781 	if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
782 		chainmode = "cbc";
783 		ivmode = "plain";
784 	}
785 
786 	if (strcmp(chainmode, "ecb") && !ivmode) {
787 		ti->error = "This chaining mode requires an IV mechanism";
788 		goto bad1;
789 	}
790 
791 	if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", chainmode,
792 		     cipher) >= CRYPTO_MAX_ALG_NAME) {
793 		ti->error = "Chain mode + cipher name is too long";
794 		goto bad1;
795 	}
796 
797 	tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
798 	if (IS_ERR(tfm)) {
799 		ti->error = "Error allocating crypto tfm";
800 		goto bad1;
801 	}
802 
803 	strcpy(cc->cipher, cipher);
804 	strcpy(cc->chainmode, chainmode);
805 	cc->tfm = tfm;
806 
807 	/*
808 	 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
809 	 * See comments at iv code
810 	 */
811 
812 	if (ivmode == NULL)
813 		cc->iv_gen_ops = NULL;
814 	else if (strcmp(ivmode, "plain") == 0)
815 		cc->iv_gen_ops = &crypt_iv_plain_ops;
816 	else if (strcmp(ivmode, "essiv") == 0)
817 		cc->iv_gen_ops = &crypt_iv_essiv_ops;
818 	else if (strcmp(ivmode, "benbi") == 0)
819 		cc->iv_gen_ops = &crypt_iv_benbi_ops;
820 	else if (strcmp(ivmode, "null") == 0)
821 		cc->iv_gen_ops = &crypt_iv_null_ops;
822 	else {
823 		ti->error = "Invalid IV mode";
824 		goto bad2;
825 	}
826 
827 	if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
828 	    cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
829 		goto bad2;
830 
831 	cc->iv_size = crypto_blkcipher_ivsize(tfm);
832 	if (cc->iv_size)
833 		/* at least a 64 bit sector number should fit in our buffer */
834 		cc->iv_size = max(cc->iv_size,
835 		                  (unsigned int)(sizeof(u64) / sizeof(u8)));
836 	else {
837 		if (cc->iv_gen_ops) {
838 			DMWARN("Selected cipher does not support IVs");
839 			if (cc->iv_gen_ops->dtr)
840 				cc->iv_gen_ops->dtr(cc);
841 			cc->iv_gen_ops = NULL;
842 		}
843 	}
844 
845 	cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
846 	if (!cc->io_pool) {
847 		ti->error = "Cannot allocate crypt io mempool";
848 		goto bad3;
849 	}
850 
851 	cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
852 	if (!cc->page_pool) {
853 		ti->error = "Cannot allocate page mempool";
854 		goto bad4;
855 	}
856 
857 	cc->bs = bioset_create(MIN_IOS, MIN_IOS);
858 	if (!cc->bs) {
859 		ti->error = "Cannot allocate crypt bioset";
860 		goto bad_bs;
861 	}
862 
863 	if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
864 		ti->error = "Error setting key";
865 		goto bad5;
866 	}
867 
868 	if (sscanf(argv[2], "%llu", &tmpll) != 1) {
869 		ti->error = "Invalid iv_offset sector";
870 		goto bad5;
871 	}
872 	cc->iv_offset = tmpll;
873 
874 	if (sscanf(argv[4], "%llu", &tmpll) != 1) {
875 		ti->error = "Invalid device sector";
876 		goto bad5;
877 	}
878 	cc->start = tmpll;
879 
880 	if (dm_get_device(ti, argv[3], cc->start, ti->len,
881 	                  dm_table_get_mode(ti->table), &cc->dev)) {
882 		ti->error = "Device lookup failed";
883 		goto bad5;
884 	}
885 
886 	if (ivmode && cc->iv_gen_ops) {
887 		if (ivopts)
888 			*(ivopts - 1) = ':';
889 		cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
890 		if (!cc->iv_mode) {
891 			ti->error = "Error kmallocing iv_mode string";
892 			goto bad5;
893 		}
894 		strcpy(cc->iv_mode, ivmode);
895 	} else
896 		cc->iv_mode = NULL;
897 
898 	ti->private = cc;
899 	return 0;
900 
901 bad5:
902 	bioset_free(cc->bs);
903 bad_bs:
904 	mempool_destroy(cc->page_pool);
905 bad4:
906 	mempool_destroy(cc->io_pool);
907 bad3:
908 	if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
909 		cc->iv_gen_ops->dtr(cc);
910 bad2:
911 	crypto_free_blkcipher(tfm);
912 bad1:
913 	/* Must zero key material before freeing */
914 	memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
915 	kfree(cc);
916 	return -EINVAL;
917 }
918 
919 static void crypt_dtr(struct dm_target *ti)
920 {
921 	struct crypt_config *cc = (struct crypt_config *) ti->private;
922 
923 	bioset_free(cc->bs);
924 	mempool_destroy(cc->page_pool);
925 	mempool_destroy(cc->io_pool);
926 
927 	kfree(cc->iv_mode);
928 	if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
929 		cc->iv_gen_ops->dtr(cc);
930 	crypto_free_blkcipher(cc->tfm);
931 	dm_put_device(ti, cc->dev);
932 
933 	/* Must zero key material before freeing */
934 	memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
935 	kfree(cc);
936 }
937 
938 static int crypt_map(struct dm_target *ti, struct bio *bio,
939 		     union map_info *map_context)
940 {
941 	struct crypt_config *cc = ti->private;
942 	struct crypt_io *io;
943 
944 	if (bio_barrier(bio))
945 		return -EOPNOTSUPP;
946 
947 	io = mempool_alloc(cc->io_pool, GFP_NOIO);
948 	io->target = ti;
949 	io->base_bio = bio;
950 	io->error = io->post_process = 0;
951 	atomic_set(&io->pending, 0);
952 	kcryptd_queue_io(io);
953 
954 	return DM_MAPIO_SUBMITTED;
955 }
956 
957 static int crypt_status(struct dm_target *ti, status_type_t type,
958 			char *result, unsigned int maxlen)
959 {
960 	struct crypt_config *cc = (struct crypt_config *) ti->private;
961 	unsigned int sz = 0;
962 
963 	switch (type) {
964 	case STATUSTYPE_INFO:
965 		result[0] = '\0';
966 		break;
967 
968 	case STATUSTYPE_TABLE:
969 		if (cc->iv_mode)
970 			DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
971 			       cc->iv_mode);
972 		else
973 			DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
974 
975 		if (cc->key_size > 0) {
976 			if ((maxlen - sz) < ((cc->key_size << 1) + 1))
977 				return -ENOMEM;
978 
979 			crypt_encode_key(result + sz, cc->key, cc->key_size);
980 			sz += cc->key_size << 1;
981 		} else {
982 			if (sz >= maxlen)
983 				return -ENOMEM;
984 			result[sz++] = '-';
985 		}
986 
987 		DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
988 				cc->dev->name, (unsigned long long)cc->start);
989 		break;
990 	}
991 	return 0;
992 }
993 
994 static void crypt_postsuspend(struct dm_target *ti)
995 {
996 	struct crypt_config *cc = ti->private;
997 
998 	set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
999 }
1000 
1001 static int crypt_preresume(struct dm_target *ti)
1002 {
1003 	struct crypt_config *cc = ti->private;
1004 
1005 	if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
1006 		DMERR("aborting resume - crypt key is not set.");
1007 		return -EAGAIN;
1008 	}
1009 
1010 	return 0;
1011 }
1012 
1013 static void crypt_resume(struct dm_target *ti)
1014 {
1015 	struct crypt_config *cc = ti->private;
1016 
1017 	clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1018 }
1019 
1020 /* Message interface
1021  *	key set <key>
1022  *	key wipe
1023  */
1024 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1025 {
1026 	struct crypt_config *cc = ti->private;
1027 
1028 	if (argc < 2)
1029 		goto error;
1030 
1031 	if (!strnicmp(argv[0], MESG_STR("key"))) {
1032 		if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1033 			DMWARN("not suspended during key manipulation.");
1034 			return -EINVAL;
1035 		}
1036 		if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1037 			return crypt_set_key(cc, argv[2]);
1038 		if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1039 			return crypt_wipe_key(cc);
1040 	}
1041 
1042 error:
1043 	DMWARN("unrecognised message received.");
1044 	return -EINVAL;
1045 }
1046 
1047 static struct target_type crypt_target = {
1048 	.name   = "crypt",
1049 	.version= {1, 5, 0},
1050 	.module = THIS_MODULE,
1051 	.ctr    = crypt_ctr,
1052 	.dtr    = crypt_dtr,
1053 	.map    = crypt_map,
1054 	.status = crypt_status,
1055 	.postsuspend = crypt_postsuspend,
1056 	.preresume = crypt_preresume,
1057 	.resume = crypt_resume,
1058 	.message = crypt_message,
1059 };
1060 
1061 static int __init dm_crypt_init(void)
1062 {
1063 	int r;
1064 
1065 	_crypt_io_pool = kmem_cache_create("dm-crypt_io",
1066 	                                   sizeof(struct crypt_io),
1067 	                                   0, 0, NULL, NULL);
1068 	if (!_crypt_io_pool)
1069 		return -ENOMEM;
1070 
1071 	_kcryptd_workqueue = create_workqueue("kcryptd");
1072 	if (!_kcryptd_workqueue) {
1073 		r = -ENOMEM;
1074 		DMERR("couldn't create kcryptd");
1075 		goto bad1;
1076 	}
1077 
1078 	r = dm_register_target(&crypt_target);
1079 	if (r < 0) {
1080 		DMERR("register failed %d", r);
1081 		goto bad2;
1082 	}
1083 
1084 	return 0;
1085 
1086 bad2:
1087 	destroy_workqueue(_kcryptd_workqueue);
1088 bad1:
1089 	kmem_cache_destroy(_crypt_io_pool);
1090 	return r;
1091 }
1092 
1093 static void __exit dm_crypt_exit(void)
1094 {
1095 	int r = dm_unregister_target(&crypt_target);
1096 
1097 	if (r < 0)
1098 		DMERR("unregister failed %d", r);
1099 
1100 	destroy_workqueue(_kcryptd_workqueue);
1101 	kmem_cache_destroy(_crypt_io_pool);
1102 }
1103 
1104 module_init(dm_crypt_init);
1105 module_exit(dm_crypt_exit);
1106 
1107 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1108 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1109 MODULE_LICENSE("GPL");
1110