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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  1 /*
  2  * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
  3  * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
  4  * Copyright (C) 2006-2008 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  */
 34 struct 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  */
 49 struct 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 
 62 struct dm_crypt_request {
 63         struct convert_context *ctx;
 64         struct scatterlist sg_in;
 65         struct scatterlist sg_out;
 66 };
 67 
 68 struct crypt_config;
 69 
 70 struct 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         const char *(*status)(struct crypt_config *cc);
 75         int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
 76 };
 77 
 78 /*
 79  * Crypt: maps a linear range of a block device
 80  * and encrypts / decrypts at the same time.
 81  */
 82 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
 83 struct crypt_config {
 84         struct dm_dev *dev;
 85         sector_t start;
 86 
 87         /*
 88          * pool for per bio private data, crypto requests and
 89          * encryption requeusts/buffer pages
 90          */
 91         mempool_t *io_pool;
 92         mempool_t *req_pool;
 93         mempool_t *page_pool;
 94         struct bio_set *bs;
 95 
 96         struct workqueue_struct *io_queue;
 97         struct workqueue_struct *crypt_queue;
 98 
 99         /*
100          * crypto related data
101          */
102         struct crypt_iv_operations *iv_gen_ops;
103         char *iv_mode;
104         union {
105                 struct crypto_cipher *essiv_tfm;
106                 int benbi_shift;
107         } iv_gen_private;
108         sector_t iv_offset;
109         unsigned int iv_size;
110 
111         /*
112          * Layout of each crypto request:
113          *
114          *   struct ablkcipher_request
115          *      context
116          *      padding
117          *   struct dm_crypt_request
118          *      padding
119          *   IV
120          *
121          * The padding is added so that dm_crypt_request and the IV are
122          * correctly aligned.
123          */
124         unsigned int dmreq_start;
125         struct ablkcipher_request *req;
126 
127         char cipher[CRYPTO_MAX_ALG_NAME];
128         char chainmode[CRYPTO_MAX_ALG_NAME];
129         struct crypto_ablkcipher *tfm;
130         unsigned long flags;
131         unsigned int key_size;
132         u8 key[0];
133 };
134 
135 #define MIN_IOS        16
136 #define MIN_POOL_PAGES 32
137 #define MIN_BIO_PAGES  8
138 
139 static struct kmem_cache *_crypt_io_pool;
140 
141 static void clone_init(struct dm_crypt_io *, struct bio *);
142 static void kcryptd_queue_crypt(struct dm_crypt_io *io);
143 
144 /*
145  * Different IV generation algorithms:
146  *
147  * plain: the initial vector is the 32-bit little-endian version of the sector
148  *        number, padded with zeros if necessary.
149  *
150  * essiv: "encrypted sector|salt initial vector", the sector number is
151  *        encrypted with the bulk cipher using a salt as key. The salt
152  *        should be derived from the bulk cipher's key via hashing.
153  *
154  * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
155  *        (needed for LRW-32-AES and possible other narrow block modes)
156  *
157  * null: the initial vector is always zero.  Provides compatibility with
158  *       obsolete loop_fish2 devices.  Do not use for new devices.
159  *
160  * plumb: unimplemented, see:
161  * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
162  */
163 
164 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
165 {
166         memset(iv, 0, cc->iv_size);
167         *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
168 
169         return 0;
170 }
171 
172 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
173                               const char *opts)
174 {
175         struct crypto_cipher *essiv_tfm;
176         struct crypto_hash *hash_tfm;
177         struct hash_desc desc;
178         struct scatterlist sg;
179         unsigned int saltsize;
180         u8 *salt;
181         int err;
182 
183         if (opts == NULL) {
184                 ti->error = "Digest algorithm missing for ESSIV mode";
185                 return -EINVAL;
186         }
187 
188         /* Hash the cipher key with the given hash algorithm */
189         hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
190         if (IS_ERR(hash_tfm)) {
191                 ti->error = "Error initializing ESSIV hash";
192                 return PTR_ERR(hash_tfm);
193         }
194 
195         saltsize = crypto_hash_digestsize(hash_tfm);
196         salt = kmalloc(saltsize, GFP_KERNEL);
197         if (salt == NULL) {
198                 ti->error = "Error kmallocing salt storage in ESSIV";
199                 crypto_free_hash(hash_tfm);
200                 return -ENOMEM;
201         }
202 
203         sg_init_one(&sg, cc->key, cc->key_size);
204         desc.tfm = hash_tfm;
205         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
206         err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
207         crypto_free_hash(hash_tfm);
208 
209         if (err) {
210                 ti->error = "Error calculating hash in ESSIV";
211                 kfree(salt);
212                 return err;
213         }
214 
215         /* Setup the essiv_tfm with the given salt */
216         essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
217         if (IS_ERR(essiv_tfm)) {
218                 ti->error = "Error allocating crypto tfm for ESSIV";
219                 kfree(salt);
220                 return PTR_ERR(essiv_tfm);
221         }
222         if (crypto_cipher_blocksize(essiv_tfm) !=
223             crypto_ablkcipher_ivsize(cc->tfm)) {
224                 ti->error = "Block size of ESSIV cipher does "
225                             "not match IV size of block cipher";
226                 crypto_free_cipher(essiv_tfm);
227                 kfree(salt);
228                 return -EINVAL;
229         }
230         err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
231         if (err) {
232                 ti->error = "Failed to set key for ESSIV cipher";
233                 crypto_free_cipher(essiv_tfm);
234                 kfree(salt);
235                 return err;
236         }
237         kfree(salt);
238 
239         cc->iv_gen_private.essiv_tfm = essiv_tfm;
240         return 0;
241 }
242 
243 static void crypt_iv_essiv_dtr(struct crypt_config *cc)
244 {
245         crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
246         cc->iv_gen_private.essiv_tfm = NULL;
247 }
248 
249 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
250 {
251         memset(iv, 0, cc->iv_size);
252         *(u64 *)iv = cpu_to_le64(sector);
253         crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
254         return 0;
255 }
256 
257 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
258                               const char *opts)
259 {
260         unsigned bs = crypto_ablkcipher_blocksize(cc->tfm);
261         int log = ilog2(bs);
262 
263         /* we need to calculate how far we must shift the sector count
264          * to get the cipher block count, we use this shift in _gen */
265 
266         if (1 << log != bs) {
267                 ti->error = "cypher blocksize is not a power of 2";
268                 return -EINVAL;
269         }
270 
271         if (log > 9) {
272                 ti->error = "cypher blocksize is > 512";
273                 return -EINVAL;
274         }
275 
276         cc->iv_gen_private.benbi_shift = 9 - log;
277 
278         return 0;
279 }
280 
281 static void crypt_iv_benbi_dtr(struct crypt_config *cc)
282 {
283 }
284 
285 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
286 {
287         __be64 val;
288 
289         memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
290 
291         val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
292         put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
293 
294         return 0;
295 }
296 
297 static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
298 {
299         memset(iv, 0, cc->iv_size);
300 
301         return 0;
302 }
303 
304 static struct crypt_iv_operations crypt_iv_plain_ops = {
305         .generator = crypt_iv_plain_gen
306 };
307 
308 static struct crypt_iv_operations crypt_iv_essiv_ops = {
309         .ctr       = crypt_iv_essiv_ctr,
310         .dtr       = crypt_iv_essiv_dtr,
311         .generator = crypt_iv_essiv_gen
312 };
313 
314 static struct crypt_iv_operations crypt_iv_benbi_ops = {
315         .ctr       = crypt_iv_benbi_ctr,
316         .dtr       = crypt_iv_benbi_dtr,
317         .generator = crypt_iv_benbi_gen
318 };
319 
320 static struct crypt_iv_operations crypt_iv_null_ops = {
321         .generator = crypt_iv_null_gen
322 };
323 
324 static void crypt_convert_init(struct crypt_config *cc,
325                                struct convert_context *ctx,
326                                struct bio *bio_out, struct bio *bio_in,
327                                sector_t sector)
328 {
329         ctx->bio_in = bio_in;
330         ctx->bio_out = bio_out;
331         ctx->offset_in = 0;
332         ctx->offset_out = 0;
333         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
334         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
335         ctx->sector = sector + cc->iv_offset;
336         init_completion(&ctx->restart);
337 }
338 
339 static struct dm_crypt_request *dmreq_of_req(struct crypt_config *cc,
340                                              struct ablkcipher_request *req)
341 {
342         return (struct dm_crypt_request *)((char *)req + cc->dmreq_start);
343 }
344 
345 static struct ablkcipher_request *req_of_dmreq(struct crypt_config *cc,
346                                                struct dm_crypt_request *dmreq)
347 {
348         return (struct ablkcipher_request *)((char *)dmreq - cc->dmreq_start);
349 }
350 
351 static int crypt_convert_block(struct crypt_config *cc,
352                                struct convert_context *ctx,
353                                struct ablkcipher_request *req)
354 {
355         struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
356         struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
357         struct dm_crypt_request *dmreq;
358         u8 *iv;
359         int r = 0;
360 
361         dmreq = dmreq_of_req(cc, req);
362         iv = (u8 *)ALIGN((unsigned long)(dmreq + 1),
363                          crypto_ablkcipher_alignmask(cc->tfm) + 1);
364 
365         dmreq->ctx = ctx;
366         sg_init_table(&dmreq->sg_in, 1);
367         sg_set_page(&dmreq->sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT,
368                     bv_in->bv_offset + ctx->offset_in);
369 
370         sg_init_table(&dmreq->sg_out, 1);
371         sg_set_page(&dmreq->sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT,
372                     bv_out->bv_offset + ctx->offset_out);
373 
374         ctx->offset_in += 1 << SECTOR_SHIFT;
375         if (ctx->offset_in >= bv_in->bv_len) {
376                 ctx->offset_in = 0;
377                 ctx->idx_in++;
378         }
379 
380         ctx->offset_out += 1 << SECTOR_SHIFT;
381         if (ctx->offset_out >= bv_out->bv_len) {
382                 ctx->offset_out = 0;
383                 ctx->idx_out++;
384         }
385 
386         if (cc->iv_gen_ops) {
387                 r = cc->iv_gen_ops->generator(cc, iv, ctx->sector);
388                 if (r < 0)
389                         return r;
390         }
391 
392         ablkcipher_request_set_crypt(req, &dmreq->sg_in, &dmreq->sg_out,
393                                      1 << SECTOR_SHIFT, iv);
394 
395         if (bio_data_dir(ctx->bio_in) == WRITE)
396                 r = crypto_ablkcipher_encrypt(req);
397         else
398                 r = crypto_ablkcipher_decrypt(req);
399 
400         return r;
401 }
402 
403 static void kcryptd_async_done(struct crypto_async_request *async_req,
404                                int error);
405 static void crypt_alloc_req(struct crypt_config *cc,
406                             struct convert_context *ctx)
407 {
408         if (!cc->req)
409                 cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);
410         ablkcipher_request_set_tfm(cc->req, cc->tfm);
411         ablkcipher_request_set_callback(cc->req, CRYPTO_TFM_REQ_MAY_BACKLOG |
412                                         CRYPTO_TFM_REQ_MAY_SLEEP,
413                                         kcryptd_async_done,
414                                         dmreq_of_req(cc, cc->req));
415 }
416 
417 /*
418  * Encrypt / decrypt data from one bio to another one (can be the same one)
419  */
420 static int crypt_convert(struct crypt_config *cc,
421                          struct convert_context *ctx)
422 {
423         int r;
424 
425         atomic_set(&ctx->pending, 1);
426 
427         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
428               ctx->idx_out < ctx->bio_out->bi_vcnt) {
429 
430                 crypt_alloc_req(cc, ctx);
431 
432                 atomic_inc(&ctx->pending);
433 
434                 r = crypt_convert_block(cc, ctx, cc->req);
435 
436                 switch (r) {
437                 /* async */
438                 case -EBUSY:
439                         wait_for_completion(&ctx->restart);
440                         INIT_COMPLETION(ctx->restart);
441                         /* fall through*/
442                 case -EINPROGRESS:
443                         cc->req = NULL;
444                         ctx->sector++;
445                         continue;
446 
447                 /* sync */
448                 case 0:
449                         atomic_dec(&ctx->pending);
450                         ctx->sector++;
451                         cond_resched();
452                         continue;
453 
454                 /* error */
455                 default:
456                         atomic_dec(&ctx->pending);
457                         return r;
458                 }
459         }
460 
461         return 0;
462 }
463 
464 static void dm_crypt_bio_destructor(struct bio *bio)
465 {
466         struct dm_crypt_io *io = bio->bi_private;
467         struct crypt_config *cc = io->target->private;
468 
469         bio_free(bio, cc->bs);
470 }
471 
472 /*
473  * Generate a new unfragmented bio with the given size
474  * This should never violate the device limitations
475  * May return a smaller bio when running out of pages, indicated by
476  * *out_of_pages set to 1.
477  */
478 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size,
479                                       unsigned *out_of_pages)
480 {
481         struct crypt_config *cc = io->target->private;
482         struct bio *clone;
483         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
484         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
485         unsigned i, len;
486         struct page *page;
487 
488         clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
489         if (!clone)
490                 return NULL;
491 
492         clone_init(io, clone);
493         *out_of_pages = 0;
494 
495         for (i = 0; i < nr_iovecs; i++) {
496                 page = mempool_alloc(cc->page_pool, gfp_mask);
497                 if (!page) {
498                         *out_of_pages = 1;
499                         break;
500                 }
501 
502                 /*
503                  * if additional pages cannot be allocated without waiting,
504                  * return a partially allocated bio, the caller will then try
505                  * to allocate additional bios while submitting this partial bio
506                  */
507                 if (i == (MIN_BIO_PAGES - 1))
508                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
509 
510                 len = (size > PAGE_SIZE) ? PAGE_SIZE : size;
511 
512                 if (!bio_add_page(clone, page, len, 0)) {
513                         mempool_free(page, cc->page_pool);
514                         break;
515                 }
516 
517                 size -= len;
518         }
519 
520         if (!clone->bi_size) {
521                 bio_put(clone);
522                 return NULL;
523         }
524 
525         return clone;
526 }
527 
528 static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
529 {
530         unsigned int i;
531         struct bio_vec *bv;
532 
533         for (i = 0; i < clone->bi_vcnt; i++) {
534                 bv = bio_iovec_idx(clone, i);
535                 BUG_ON(!bv->bv_page);
536                 mempool_free(bv->bv_page, cc->page_pool);
537                 bv->bv_page = NULL;
538         }
539 }
540 
541 static struct dm_crypt_io *crypt_io_alloc(struct dm_target *ti,
542                                           struct bio *bio, sector_t sector)
543 {
544         struct crypt_config *cc = ti->private;
545         struct dm_crypt_io *io;
546 
547         io = mempool_alloc(cc->io_pool, GFP_NOIO);
548         io->target = ti;
549         io->base_bio = bio;
550         io->sector = sector;
551         io->error = 0;
552         io->base_io = NULL;
553         atomic_set(&io->pending, 0);
554 
555         return io;
556 }
557 
558 static void crypt_inc_pending(struct dm_crypt_io *io)
559 {
560         atomic_inc(&io->pending);
561 }
562 
563 /*
564  * One of the bios was finished. Check for completion of
565  * the whole request and correctly clean up the buffer.
566  * If base_io is set, wait for the last fragment to complete.
567  */
568 static void crypt_dec_pending(struct dm_crypt_io *io)
569 {
570         struct crypt_config *cc = io->target->private;
571         struct bio *base_bio = io->base_bio;
572         struct dm_crypt_io *base_io = io->base_io;
573         int error = io->error;
574 
575         if (!atomic_dec_and_test(&io->pending))
576                 return;
577 
578         mempool_free(io, cc->io_pool);
579 
580         if (likely(!base_io))
581                 bio_endio(base_bio, error);
582         else {
583                 if (error && !base_io->error)
584                         base_io->error = error;
585                 crypt_dec_pending(base_io);
586         }
587 }
588 
589 /*
590  * kcryptd/kcryptd_io:
591  *
592  * Needed because it would be very unwise to do decryption in an
593  * interrupt context.
594  *
595  * kcryptd performs the actual encryption or decryption.
596  *
597  * kcryptd_io performs the IO submission.
598  *
599  * They must be separated as otherwise the final stages could be
600  * starved by new requests which can block in the first stages due
601  * to memory allocation.
602  */
603 static void crypt_endio(struct bio *clone, int error)
604 {
605         struct dm_crypt_io *io = clone->bi_private;
606         struct crypt_config *cc = io->target->private;
607         unsigned rw = bio_data_dir(clone);
608 
609         if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
610                 error = -EIO;
611 
612         /*
613          * free the processed pages
614          */
615         if (rw == WRITE)
616                 crypt_free_buffer_pages(cc, clone);
617 
618         bio_put(clone);
619 
620         if (rw == READ && !error) {
621                 kcryptd_queue_crypt(io);
622                 return;
623         }
624 
625         if (unlikely(error))
626                 io->error = error;
627 
628         crypt_dec_pending(io);
629 }
630 
631 static void clone_init(struct dm_crypt_io *io, struct bio *clone)
632 {
633         struct crypt_config *cc = io->target->private;
634 
635         clone->bi_private = io;
636         clone->bi_end_io  = crypt_endio;
637         clone->bi_bdev    = cc->dev->bdev;
638         clone->bi_rw      = io->base_bio->bi_rw;
639         clone->bi_destructor = dm_crypt_bio_destructor;
640 }
641 
642 static void kcryptd_io_read(struct dm_crypt_io *io)
643 {
644         struct crypt_config *cc = io->target->private;
645         struct bio *base_bio = io->base_bio;
646         struct bio *clone;
647 
648         crypt_inc_pending(io);
649 
650         /*
651          * The block layer might modify the bvec array, so always
652          * copy the required bvecs because we need the original
653          * one in order to decrypt the whole bio data *afterwards*.
654          */
655         clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
656         if (unlikely(!clone)) {
657                 io->error = -ENOMEM;
658                 crypt_dec_pending(io);
659                 return;
660         }
661 
662         clone_init(io, clone);
663         clone->bi_idx = 0;
664         clone->bi_vcnt = bio_segments(base_bio);
665         clone->bi_size = base_bio->bi_size;
666         clone->bi_sector = cc->start + io->sector;
667         memcpy(clone->bi_io_vec, bio_iovec(base_bio),
668                sizeof(struct bio_vec) * clone->bi_vcnt);
669 
670         generic_make_request(clone);
671 }
672 
673 static void kcryptd_io_write(struct dm_crypt_io *io)
674 {
675         struct bio *clone = io->ctx.bio_out;
676         generic_make_request(clone);
677 }
678 
679 static void kcryptd_io(struct work_struct *work)
680 {
681         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
682 
683         if (bio_data_dir(io->base_bio) == READ)
684                 kcryptd_io_read(io);
685         else
686                 kcryptd_io_write(io);
687 }
688 
689 static void kcryptd_queue_io(struct dm_crypt_io *io)
690 {
691         struct crypt_config *cc = io->target->private;
692 
693         INIT_WORK(&io->work, kcryptd_io);
694         queue_work(cc->io_queue, &io->work);
695 }
696 
697 static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io,
698                                           int error, int async)
699 {
700         struct bio *clone = io->ctx.bio_out;
701         struct crypt_config *cc = io->target->private;
702 
703         if (unlikely(error < 0)) {
704                 crypt_free_buffer_pages(cc, clone);
705                 bio_put(clone);
706                 io->error = -EIO;
707                 crypt_dec_pending(io);
708                 return;
709         }
710 
711         /* crypt_convert should have filled the clone bio */
712         BUG_ON(io->ctx.idx_out < clone->bi_vcnt);
713 
714         clone->bi_sector = cc->start + io->sector;
715 
716         if (async)
717                 kcryptd_queue_io(io);
718         else
719                 generic_make_request(clone);
720 }
721 
722 static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
723 {
724         struct crypt_config *cc = io->target->private;
725         struct bio *clone;
726         struct dm_crypt_io *new_io;
727         int crypt_finished;
728         unsigned out_of_pages = 0;
729         unsigned remaining = io->base_bio->bi_size;
730         sector_t sector = io->sector;
731         int r;
732 
733         /*
734          * Prevent io from disappearing until this function completes.
735          */
736         crypt_inc_pending(io);
737         crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector);
738 
739         /*
740          * The allocated buffers can be smaller than the whole bio,
741          * so repeat the whole process until all the data can be handled.
742          */
743         while (remaining) {
744                 clone = crypt_alloc_buffer(io, remaining, &out_of_pages);
745                 if (unlikely(!clone)) {
746                         io->error = -ENOMEM;
747                         break;
748                 }
749 
750                 io->ctx.bio_out = clone;
751                 io->ctx.idx_out = 0;
752 
753                 remaining -= clone->bi_size;
754                 sector += bio_sectors(clone);
755 
756                 crypt_inc_pending(io);
757                 r = crypt_convert(cc, &io->ctx);
758                 crypt_finished = atomic_dec_and_test(&io->ctx.pending);
759 
760                 /* Encryption was already finished, submit io now */
761                 if (crypt_finished) {
762                         kcryptd_crypt_write_io_submit(io, r, 0);
763 
764                         /*
765                          * If there was an error, do not try next fragments.
766                          * For async, error is processed in async handler.
767                          */
768                         if (unlikely(r < 0))
769                                 break;
770 
771                         io->sector = sector;
772                 }
773 
774                 /*
775                  * Out of memory -> run queues
776                  * But don't wait if split was due to the io size restriction
777                  */
778                 if (unlikely(out_of_pages))
779                         congestion_wait(BLK_RW_ASYNC, HZ/100);
780 
781                 /*
782                  * With async crypto it is unsafe to share the crypto context
783                  * between fragments, so switch to a new dm_crypt_io structure.
784                  */
785                 if (unlikely(!crypt_finished && remaining)) {
786                         new_io = crypt_io_alloc(io->target, io->base_bio,
787                                                 sector);
788                         crypt_inc_pending(new_io);
789                         crypt_convert_init(cc, &new_io->ctx, NULL,
790                                            io->base_bio, sector);
791                         new_io->ctx.idx_in = io->ctx.idx_in;
792                         new_io->ctx.offset_in = io->ctx.offset_in;
793 
794                         /*
795                          * Fragments after the first use the base_io
796                          * pending count.
797                          */
798                         if (!io->base_io)
799                                 new_io->base_io = io;
800                         else {
801                                 new_io->base_io = io->base_io;
802                                 crypt_inc_pending(io->base_io);
803                                 crypt_dec_pending(io);
804                         }
805 
806                         io = new_io;
807                 }
808         }
809 
810         crypt_dec_pending(io);
811 }
812 
813 static void kcryptd_crypt_read_done(struct dm_crypt_io *io, int error)
814 {
815         if (unlikely(error < 0))
816                 io->error = -EIO;
817 
818         crypt_dec_pending(io);
819 }
820 
821 static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)
822 {
823         struct crypt_config *cc = io->target->private;
824         int r = 0;
825 
826         crypt_inc_pending(io);
827 
828         crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,
829                            io->sector);
830 
831         r = crypt_convert(cc, &io->ctx);
832 
833         if (atomic_dec_and_test(&io->ctx.pending))
834                 kcryptd_crypt_read_done(io, r);
835 
836         crypt_dec_pending(io);
837 }
838 
839 static void kcryptd_async_done(struct crypto_async_request *async_req,
840                                int error)
841 {
842         struct dm_crypt_request *dmreq = async_req->data;
843         struct convert_context *ctx = dmreq->ctx;
844         struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
845         struct crypt_config *cc = io->target->private;
846 
847         if (error == -EINPROGRESS) {
848                 complete(&ctx->restart);
849                 return;
850         }
851 
852         mempool_free(req_of_dmreq(cc, dmreq), cc->req_pool);
853 
854         if (!atomic_dec_and_test(&ctx->pending))
855                 return;
856 
857         if (bio_data_dir(io->base_bio) == READ)
858                 kcryptd_crypt_read_done(io, error);
859         else
860                 kcryptd_crypt_write_io_submit(io, error, 1);
861 }
862 
863 static void kcryptd_crypt(struct work_struct *work)
864 {
865         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
866 
867         if (bio_data_dir(io->base_bio) == READ)
868                 kcryptd_crypt_read_convert(io);
869         else
870                 kcryptd_crypt_write_convert(io);
871 }
872 
873 static void kcryptd_queue_crypt(struct dm_crypt_io *io)
874 {
875         struct crypt_config *cc = io->target->private;
876 
877         INIT_WORK(&io->work, kcryptd_crypt);
878         queue_work(cc->crypt_queue, &io->work);
879 }
880 
881 /*
882  * Decode key from its hex representation
883  */
884 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
885 {
886         char buffer[3];
887         char *endp;
888         unsigned int i;
889 
890         buffer[2] = '\0';
891 
892         for (i = 0; i < size; i++) {
893                 buffer[0] = *hex++;
894                 buffer[1] = *hex++;
895 
896                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
897 
898                 if (endp != &buffer[2])
899                         return -EINVAL;
900         }
901 
902         if (*hex != '\0')
903                 return -EINVAL;
904 
905         return 0;
906 }
907 
908 /*
909  * Encode key into its hex representation
910  */
911 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
912 {
913         unsigned int i;
914 
915         for (i = 0; i < size; i++) {
916                 sprintf(hex, "%02x", *key);
917                 hex += 2;
918                 key++;
919         }
920 }
921 
922 static int crypt_set_key(struct crypt_config *cc, char *key)
923 {
924         unsigned key_size = strlen(key) >> 1;
925 
926         if (cc->key_size && cc->key_size != key_size)
927                 return -EINVAL;
928 
929         cc->key_size = key_size; /* initial settings */
930 
931         if ((!key_size && strcmp(key, "-")) ||
932            (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
933                 return -EINVAL;
934 
935         set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
936 
937         return 0;
938 }
939 
940 static int crypt_wipe_key(struct crypt_config *cc)
941 {
942         clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
943         memset(&cc->key, 0, cc->key_size * sizeof(u8));
944         return 0;
945 }
946 
947 /*
948  * Construct an encryption mapping:
949  * <cipher> <key> <iv_offset> <dev_path> <start>
950  */
951 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
952 {
953         struct crypt_config *cc;
954         struct crypto_ablkcipher *tfm;
955         char *tmp;
956         char *cipher;
957         char *chainmode;
958         char *ivmode;
959         char *ivopts;
960         unsigned int key_size;
961         unsigned long long tmpll;
962 
963         if (argc != 5) {
964                 ti->error = "Not enough arguments";
965                 return -EINVAL;
966         }
967 
968         tmp = argv[0];
969         cipher = strsep(&tmp, "-");
970         chainmode = strsep(&tmp, "-");
971         ivopts = strsep(&tmp, "-");
972         ivmode = strsep(&ivopts, ":");
973 
974         if (tmp)
975                 DMWARN("Unexpected additional cipher options");
976 
977         key_size = strlen(argv[1]) >> 1;
978 
979         cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
980         if (cc == NULL) {
981                 ti->error =
982                         "Cannot allocate transparent encryption context";
983                 return -ENOMEM;
984         }
985 
986         if (crypt_set_key(cc, argv[1])) {
987                 ti->error = "Error decoding key";
988                 goto bad_cipher;
989         }
990 
991         /* Compatiblity mode for old dm-crypt cipher strings */
992         if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
993                 chainmode = "cbc";
994                 ivmode = "plain";
995         }
996 
997         if (strcmp(chainmode, "ecb") && !ivmode) {
998                 ti->error = "This chaining mode requires an IV mechanism";
999                 goto bad_cipher;
1000         }
1001 
1002         if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)",
1003                      chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) {
1004                 ti->error = "Chain mode + cipher name is too long";
1005                 goto bad_cipher;
1006         }
1007 
1008         tfm = crypto_alloc_ablkcipher(cc->cipher, 0, 0);
1009         if (IS_ERR(tfm)) {
1010                 ti->error = "Error allocating crypto tfm";
1011                 goto bad_cipher;
1012         }
1013 
1014         strcpy(cc->cipher, cipher);
1015         strcpy(cc->chainmode, chainmode);
1016         cc->tfm = tfm;
1017 
1018         /*
1019          * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
1020          * See comments at iv code
1021          */
1022 
1023         if (ivmode == NULL)
1024                 cc->iv_gen_ops = NULL;
1025         else if (strcmp(ivmode, "plain") == 0)
1026                 cc->iv_gen_ops = &crypt_iv_plain_ops;
1027         else if (strcmp(ivmode, "essiv") == 0)
1028                 cc->iv_gen_ops = &crypt_iv_essiv_ops;
1029         else if (strcmp(ivmode, "benbi") == 0)
1030                 cc->iv_gen_ops = &crypt_iv_benbi_ops;
1031         else if (strcmp(ivmode, "null") == 0)
1032                 cc->iv_gen_ops = &crypt_iv_null_ops;
1033         else {
1034                 ti->error = "Invalid IV mode";
1035                 goto bad_ivmode;
1036         }
1037 
1038         if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
1039             cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
1040                 goto bad_ivmode;
1041 
1042         cc->iv_size = crypto_ablkcipher_ivsize(tfm);
1043         if (cc->iv_size)
1044                 /* at least a 64 bit sector number should fit in our buffer */
1045                 cc->iv_size = max(cc->iv_size,
1046                                   (unsigned int)(sizeof(u64) / sizeof(u8)));
1047         else {
1048                 if (cc->iv_gen_ops) {
1049                         DMWARN("Selected cipher does not support IVs");
1050                         if (cc->iv_gen_ops->dtr)
1051                                 cc->iv_gen_ops->dtr(cc);
1052                         cc->iv_gen_ops = NULL;
1053                 }
1054         }
1055 
1056         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
1057         if (!cc->io_pool) {
1058                 ti->error = "Cannot allocate crypt io mempool";
1059                 goto bad_slab_pool;
1060         }
1061 
1062         cc->dmreq_start = sizeof(struct ablkcipher_request);
1063         cc->dmreq_start += crypto_ablkcipher_reqsize(tfm);
1064         cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment());
1065         cc->dmreq_start += crypto_ablkcipher_alignmask(tfm) &
1066                            ~(crypto_tfm_ctx_alignment() - 1);
1067 
1068         cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
1069                         sizeof(struct dm_crypt_request) + cc->iv_size);
1070         if (!cc->req_pool) {
1071                 ti->error = "Cannot allocate crypt request mempool";
1072                 goto bad_req_pool;
1073         }
1074         cc->req = NULL;
1075 
1076         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
1077         if (!cc->page_pool) {
1078                 ti->error = "Cannot allocate page mempool";
1079                 goto bad_page_pool;
1080         }
1081 
1082         cc->bs = bioset_create(MIN_IOS, 0);
1083         if (!cc->bs) {
1084                 ti->error = "Cannot allocate crypt bioset";
1085                 goto bad_bs;
1086         }
1087 
1088         if (crypto_ablkcipher_setkey(tfm, cc->key, key_size) < 0) {
1089                 ti->error = "Error setting key";
1090                 goto bad_device;
1091         }
1092 
1093         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
1094                 ti->error = "Invalid iv_offset sector";
1095                 goto bad_device;
1096         }
1097         cc->iv_offset = tmpll;
1098 
1099         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
1100                 ti->error = "Invalid device sector";
1101                 goto bad_device;
1102         }
1103         cc->start = tmpll;
1104 
1105         if (dm_get_device(ti, argv[3], cc->start, ti->len,
1106                           dm_table_get_mode(ti->table), &cc->dev)) {
1107                 ti->error = "Device lookup failed";
1108                 goto bad_device;
1109         }
1110 
1111         if (ivmode && cc->iv_gen_ops) {
1112                 if (ivopts)
1113                         *(ivopts - 1) = ':';
1114                 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
1115                 if (!cc->iv_mode) {
1116                         ti->error = "Error kmallocing iv_mode string";
1117                         goto bad_ivmode_string;
1118                 }
1119                 strcpy(cc->iv_mode, ivmode);
1120         } else
1121                 cc->iv_mode = NULL;
1122 
1123         cc->io_queue = create_singlethread_workqueue("kcryptd_io");
1124         if (!cc->io_queue) {
1125                 ti->error = "Couldn't create kcryptd io queue";
1126                 goto bad_io_queue;
1127         }
1128 
1129         cc->crypt_queue = create_singlethread_workqueue("kcryptd");
1130         if (!cc->crypt_queue) {
1131                 ti->error = "Couldn't create kcryptd queue";
1132                 goto bad_crypt_queue;
1133         }
1134 
1135         ti->num_flush_requests = 1;
1136         ti->private = cc;
1137         return 0;
1138 
1139 bad_crypt_queue:
1140         destroy_workqueue(cc->io_queue);
1141 bad_io_queue:
1142         kfree(cc->iv_mode);
1143 bad_ivmode_string:
1144         dm_put_device(ti, cc->dev);
1145 bad_device:
1146         bioset_free(cc->bs);
1147 bad_bs:
1148         mempool_destroy(cc->page_pool);
1149 bad_page_pool:
1150         mempool_destroy(cc->req_pool);
1151 bad_req_pool:
1152         mempool_destroy(cc->io_pool);
1153 bad_slab_pool:
1154         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
1155                 cc->iv_gen_ops->dtr(cc);
1156 bad_ivmode:
1157         crypto_free_ablkcipher(tfm);
1158 bad_cipher:
1159         /* Must zero key material before freeing */
1160         kzfree(cc);
1161         return -EINVAL;
1162 }
1163 
1164 static void crypt_dtr(struct dm_target *ti)
1165 {
1166         struct crypt_config *cc = (struct crypt_config *) ti->private;
1167 
1168         destroy_workqueue(cc->io_queue);
1169         destroy_workqueue(cc->crypt_queue);
1170 
1171         if (cc->req)
1172                 mempool_free(cc->req, cc->req_pool);
1173 
1174         bioset_free(cc->bs);
1175         mempool_destroy(cc->page_pool);
1176         mempool_destroy(cc->req_pool);
1177         mempool_destroy(cc->io_pool);
1178 
1179         kfree(cc->iv_mode);
1180         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
1181                 cc->iv_gen_ops->dtr(cc);
1182         crypto_free_ablkcipher(cc->tfm);
1183         dm_put_device(ti, cc->dev);
1184 
1185         /* Must zero key material before freeing */
1186         kzfree(cc);
1187 }
1188 
1189 static int crypt_map(struct dm_target *ti, struct bio *bio,
1190                      union map_info *map_context)
1191 {
1192         struct dm_crypt_io *io;
1193         struct crypt_config *cc;
1194 
1195         if (unlikely(bio_empty_barrier(bio))) {
1196                 cc = ti->private;
1197                 bio->bi_bdev = cc->dev->bdev;
1198                 return DM_MAPIO_REMAPPED;
1199         }
1200 
1201         io = crypt_io_alloc(ti, bio, bio->bi_sector - ti->begin);
1202 
1203         if (bio_data_dir(io->base_bio) == READ)
1204                 kcryptd_queue_io(io);
1205         else
1206                 kcryptd_queue_crypt(io);
1207 
1208         return DM_MAPIO_SUBMITTED;
1209 }
1210 
1211 static int crypt_status(struct dm_target *ti, status_type_t type,
1212                         char *result, unsigned int maxlen)
1213 {
1214         struct crypt_config *cc = (struct crypt_config *) ti->private;
1215         unsigned int sz = 0;
1216 
1217         switch (type) {
1218         case STATUSTYPE_INFO:
1219                 result[0] = '\0';
1220                 break;
1221 
1222         case STATUSTYPE_TABLE:
1223                 if (cc->iv_mode)
1224                         DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
1225                                cc->iv_mode);
1226                 else
1227                         DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
1228 
1229                 if (cc->key_size > 0) {
1230                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
1231                                 return -ENOMEM;
1232 
1233                         crypt_encode_key(result + sz, cc->key, cc->key_size);
1234                         sz += cc->key_size << 1;
1235                 } else {
1236                         if (sz >= maxlen)
1237                                 return -ENOMEM;
1238                         result[sz++] = '-';
1239                 }
1240 
1241                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
1242                                 cc->dev->name, (unsigned long long)cc->start);
1243                 break;
1244         }
1245         return 0;
1246 }
1247 
1248 static void crypt_postsuspend(struct dm_target *ti)
1249 {
1250         struct crypt_config *cc = ti->private;
1251 
1252         set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1253 }
1254 
1255 static int crypt_preresume(struct dm_target *ti)
1256 {
1257         struct crypt_config *cc = ti->private;
1258 
1259         if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
1260                 DMERR("aborting resume - crypt key is not set.");
1261                 return -EAGAIN;
1262         }
1263 
1264         return 0;
1265 }
1266 
1267 static void crypt_resume(struct dm_target *ti)
1268 {
1269         struct crypt_config *cc = ti->private;
1270 
1271         clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1272 }
1273 
1274 /* Message interface
1275  *      key set <key>
1276  *      key wipe
1277  */
1278 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1279 {
1280         struct crypt_config *cc = ti->private;
1281 
1282         if (argc < 2)
1283                 goto error;
1284 
1285         if (!strnicmp(argv[0], MESG_STR("key"))) {
1286                 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1287                         DMWARN("not suspended during key manipulation.");
1288                         return -EINVAL;
1289                 }
1290                 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1291                         return crypt_set_key(cc, argv[2]);
1292                 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1293                         return crypt_wipe_key(cc);
1294         }
1295 
1296 error:
1297         DMWARN("unrecognised message received.");
1298         return -EINVAL;
1299 }
1300 
1301 static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
1302                        struct bio_vec *biovec, int max_size)
1303 {
1304         struct crypt_config *cc = ti->private;
1305         struct request_queue *q = bdev_get_queue(cc->dev->bdev);
1306 
1307         if (!q->merge_bvec_fn)
1308                 return max_size;
1309 
1310         bvm->bi_bdev = cc->dev->bdev;
1311         bvm->bi_sector = cc->start + bvm->bi_sector - ti->begin;
1312 
1313         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
1314 }
1315 
1316 static int crypt_iterate_devices(struct dm_target *ti,
1317                                  iterate_devices_callout_fn fn, void *data)
1318 {
1319         struct crypt_config *cc = ti->private;
1320 
1321         return fn(ti, cc->dev, cc->start, ti->len, data);
1322 }
1323 
1324 static struct target_type crypt_target = {
1325         .name   = "crypt",
1326         .version = {1, 7, 0},
1327         .module = THIS_MODULE,
1328         .ctr    = crypt_ctr,
1329         .dtr    = crypt_dtr,
1330         .map    = crypt_map,
1331         .status = crypt_status,
1332         .postsuspend = crypt_postsuspend,
1333         .preresume = crypt_preresume,
1334         .resume = crypt_resume,
1335         .message = crypt_message,
1336         .merge  = crypt_merge,
1337         .iterate_devices = crypt_iterate_devices,
1338 };
1339 
1340 static int __init dm_crypt_init(void)
1341 {
1342         int r;
1343 
1344         _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
1345         if (!_crypt_io_pool)
1346                 return -ENOMEM;
1347 
1348         r = dm_register_target(&crypt_target);
1349         if (r < 0) {
1350                 DMERR("register failed %d", r);
1351                 kmem_cache_destroy(_crypt_io_pool);
1352         }
1353 
1354         return r;
1355 }
1356 
1357 static void __exit dm_crypt_exit(void)
1358 {
1359         dm_unregister_target(&crypt_target);
1360         kmem_cache_destroy(_crypt_io_pool);
1361 }
1362 
1363 module_init(dm_crypt_init);
1364 module_exit(dm_crypt_exit);
1365 
1366 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1367 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1368 MODULE_LICENSE("GPL");
1369 
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