drivers/md/dm-crypt.c

   1 /*
   2  * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/init.h>
   9 #include <linux/kernel.h>
  10 #include <linux/bio.h>
  11 #include <linux/blkdev.h>
  12 #include <linux/mempool.h>
  13 #include <linux/slab.h>
  14 #include <linux/crypto.h>
  15 #include <linux/workqueue.h>
  16 #include <asm/atomic.h>
  17 #include <asm/scatterlist.h>
  18
  19 #include "dm.h"
  20
  21 #define PFX     "crypt: "
  22
  23 /*
  24  * per bio private data
  25  */
  26 struct crypt_io {
  27         struct dm_target *target;
  28         struct bio *bio;
  29         struct bio *first_clone;
  30         struct work_struct work;
  31         atomic_t pending;
  32         int error;
  33 };
  34
  35 /*
  36  * context holding the current state of a multi-part conversion
  37  */
  38 struct convert_context {
  39         struct bio *bio_in;
  40         struct bio *bio_out;
  41         unsigned int offset_in;
  42         unsigned int offset_out;
  43         int idx_in;
  44         int idx_out;
  45         sector_t sector;
  46         int write;
  47 };
  48
  49 /*
  50  * Crypt: maps a linear range of a block device
  51  * and encrypts / decrypts at the same time.
  52  */
  53 struct crypt_config {
  54         struct dm_dev *dev;
  55         sector_t start;
  56
  57         /*
  58          * pool for per bio private data and
  59          * for encryption buffer pages
  60          */
  61         mempool_t *io_pool;
  62         mempool_t *page_pool;
  63
  64         /*
  65          * crypto related data
  66          */
  67         struct crypto_tfm *tfm;
  68         sector_t iv_offset;
  69         int (*iv_generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
  70         int iv_size;
  71         int key_size;
  72         u8 key[0];
  73 };
  74
  75 #define MIN_IOS        256
  76 #define MIN_POOL_PAGES 32
  77 #define MIN_BIO_PAGES  8
  78
  79 static kmem_cache_t *_crypt_io_pool;
  80
  81 /*
  82  * Mempool alloc and free functions for the page
  83  */
  84 static void *mempool_alloc_page(int gfp_mask, void *data)
  85 {
  86         return alloc_page(gfp_mask);
  87 }
  88
  89 static void mempool_free_page(void *page, void *data)
  90 {
  91         __free_page(page);
  92 }
  93
  94
  95 /*
  96  * Different IV generation algorithms
  97  */
  98 static int crypt_iv_plain(struct crypt_config *cc, u8 *iv, sector_t sector)
  99 {
 100         *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
 101         if (cc->iv_size > sizeof(u32) / sizeof(u8))
 102                 memset(iv + (sizeof(u32) / sizeof(u8)), 0,
 103                        cc->iv_size - (sizeof(u32) / sizeof(u8)));
 104
 105         return 0;
 106 }
 107
 108 static inline int
 109 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
 110                           struct scatterlist *in, unsigned int length,
 111                           int write, sector_t sector)
 112 {
 113         u8 iv[cc->iv_size];
 114         int r;
 115
 116         if (cc->iv_generator) {
 117                 r = cc->iv_generator(cc, iv, sector);
 118                 if (r < 0)
 119                         return r;
 120
 121                 if (write)
 122                         r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv);
 123                 else
 124                         r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv);
 125         } else {
 126                 if (write)
 127                         r = crypto_cipher_encrypt(cc->tfm, out, in, length);
 128                 else
 129                         r = crypto_cipher_decrypt(cc->tfm, out, in, length);
 130         }
 131
 132         return r;
 133 }
 134
 135 static void
 136 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
 137                    struct bio *bio_out, struct bio *bio_in,
 138                    sector_t sector, int write)
 139 {
 140         ctx->bio_in = bio_in;
 141         ctx->bio_out = bio_out;
 142         ctx->offset_in = 0;
 143         ctx->offset_out = 0;
 144         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
 145         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
 146         ctx->sector = sector + cc->iv_offset;
 147         ctx->write = write;
 148 }
 149
 150 /*
 151  * Encrypt / decrypt data from one bio to another one (can be the same one)
 152  */
 153 static int crypt_convert(struct crypt_config *cc,
 154                          struct convert_context *ctx)
 155 {
 156         int r = 0;
 157
 158         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 159               ctx->idx_out < ctx->bio_out->bi_vcnt) {
 160                 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 161                 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 162                 struct scatterlist sg_in = {
 163                         .page = bv_in->bv_page,
 164                         .offset = bv_in->bv_offset + ctx->offset_in,
 165                         .length = 1 << SECTOR_SHIFT
 166                 };
 167                 struct scatterlist sg_out = {
 168                         .page = bv_out->bv_page,
 169                         .offset = bv_out->bv_offset + ctx->offset_out,
 170                         .length = 1 << SECTOR_SHIFT
 171                 };
 172
 173                 ctx->offset_in += sg_in.length;
 174                 if (ctx->offset_in >= bv_in->bv_len) {
 175                         ctx->offset_in = 0;
 176                         ctx->idx_in++;
 177                 }
 178
 179                 ctx->offset_out += sg_out.length;
 180                 if (ctx->offset_out >= bv_out->bv_len) {
 181                         ctx->offset_out = 0;
 182                         ctx->idx_out++;
 183                 }
 184
 185                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 186                                               ctx->write, ctx->sector);
 187                 if (r < 0)
 188                         break;
 189
 190                 ctx->sector++;
 191         }
 192
 193         return r;
 194 }
 195
 196 /*
 197  * Generate a new unfragmented bio with the given size
 198  * This should never violate the device limitations
 199  * May return a smaller bio when running out of pages
 200  */
 201 static struct bio *
 202 crypt_alloc_buffer(struct crypt_config *cc, unsigned int size,
 203                    struct bio *base_bio, int *bio_vec_idx)
 204 {
 205         struct bio *bio;
 206         int nr_iovecs = dm_div_up(size, PAGE_SIZE);
 207         int gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 208         int flags = current->flags;
 209         int i;
 210
 211         /*
 212          * Tell VM to act less aggressively and fail earlier.
 213          * This is not necessary but increases throughput.
 214          * FIXME: Is this really intelligent?
 215          */
 216         current->flags &= ~PF_MEMALLOC;
 217
 218         if (base_bio)
 219                 bio = bio_clone(base_bio, GFP_NOIO);
 220         else
 221                 bio = bio_alloc(GFP_NOIO, nr_iovecs);
 222         if (!bio) {
 223                 if (flags & PF_MEMALLOC)
 224                         current->flags |= PF_MEMALLOC;
 225                 return NULL;
 226         }
 227
 228         /* if the last bio was not complete, continue where that one ended */
 229         bio->bi_idx = *bio_vec_idx;
 230         bio->bi_vcnt = *bio_vec_idx;
 231         bio->bi_size = 0;
 232         bio->bi_flags &= ~(1 << BIO_SEG_VALID);
 233
 234         /* bio->bi_idx pages have already been allocated */
 235         size -= bio->bi_idx * PAGE_SIZE;
 236
 237         for(i = bio->bi_idx; i < nr_iovecs; i++) {
 238                 struct bio_vec *bv = bio_iovec_idx(bio, i);
 239
 240                 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
 241                 if (!bv->bv_page)
 242                         break;
 243
 244                 /*
 245                  * if additional pages cannot be allocated without waiting,
 246                  * return a partially allocated bio, the caller will then try
 247                  * to allocate additional bios while submitting this partial bio
 248                  */
 249                 if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1))
 250                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 251
 252                 bv->bv_offset = 0;
 253                 if (size > PAGE_SIZE)
 254                         bv->bv_len = PAGE_SIZE;
 255                 else
 256                         bv->bv_len = size;
 257
 258                 bio->bi_size += bv->bv_len;
 259                 bio->bi_vcnt++;
 260                 size -= bv->bv_len;
 261         }
 262
 263         if (flags & PF_MEMALLOC)
 264                 current->flags |= PF_MEMALLOC;
 265
 266         if (!bio->bi_size) {
 267                 bio_put(bio);
 268                 return NULL;
 269         }
 270
 271         /*
 272          * Remember the last bio_vec allocated to be able
 273          * to correctly continue after the splitting.
 274          */
 275         *bio_vec_idx = bio->bi_vcnt;
 276
 277         return bio;
 278 }
 279
 280 static void crypt_free_buffer_pages(struct crypt_config *cc,
 281                                     struct bio *bio, unsigned int bytes)
 282 {
 283         unsigned int start, end;
 284         struct bio_vec *bv;
 285         int i;
 286
 287         /*
 288          * This is ugly, but Jens Axboe thinks that using bi_idx in the
 289          * endio function is too dangerous at the moment, so I calculate the
 290          * correct position using bi_vcnt and bi_size.
 291          * The bv_offset and bv_len fields might already be modified but we
 292          * know that we always allocated whole pages.
 293          * A fix to the bi_idx issue in the kernel is in the works, so
 294          * we will hopefully be able to revert to the cleaner solution soon.
 295          */
 296         i = bio->bi_vcnt - 1;
 297         bv = bio_iovec_idx(bio, i);
 298         end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size;
 299         start = end - bytes;
 300
 301         start >>= PAGE_SHIFT;
 302         if (!bio->bi_size)
 303                 end = bio->bi_vcnt;
 304         else
 305                 end >>= PAGE_SHIFT;
 306
 307         for(i = start; i < end; i++) {
 308                 bv = bio_iovec_idx(bio, i);
 309                 BUG_ON(!bv->bv_page);
 310                 mempool_free(bv->bv_page, cc->page_pool);
 311                 bv->bv_page = NULL;
 312         }
 313 }
 314
 315 /*
 316  * One of the bios was finished. Check for completion of
 317  * the whole request and correctly clean up the buffer.
 318  */
 319 static void dec_pending(struct crypt_io *io, int error)
 320 {
 321         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 322
 323         if (error < 0)
 324                 io->error = error;
 325
 326         if (!atomic_dec_and_test(&io->pending))
 327                 return;
 328
 329         if (io->first_clone)
 330                 bio_put(io->first_clone);
 331
 332         bio_endio(io->bio, io->bio->bi_size, io->error);
 333
 334         mempool_free(io, cc->io_pool);
 335 }
 336
 337 /*
 338  * kcryptd:
 339  *
 340  * Needed because it would be very unwise to do decryption in an
 341  * interrupt context, so bios returning from read requests get
 342  * queued here.
 343  */
 344 static struct workqueue_struct *_kcryptd_workqueue;
 345
 346 static void kcryptd_do_work(void *data)
 347 {
 348         struct crypt_io *io = (struct crypt_io *) data;
 349         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 350         struct convert_context ctx;
 351         int r;
 352
 353         crypt_convert_init(cc, &ctx, io->bio, io->bio,
 354                            io->bio->bi_sector - io->target->begin, 0);
 355         r = crypt_convert(cc, &ctx);
 356
 357         dec_pending(io, r);
 358 }
 359
 360 static void kcryptd_queue_io(struct crypt_io *io)
 361 {
 362         INIT_WORK(&io->work, kcryptd_do_work, io);
 363         queue_work(_kcryptd_workqueue, &io->work);
 364 }
 365
 366 /*
 367  * Decode key from its hex representation
 368  */
 369 static int crypt_decode_key(u8 *key, char *hex, int size)
 370 {
 371         char buffer[3];
 372         char *endp;
 373         int i;
 374
 375         buffer[2] = '\0';
 376
 377         for(i = 0; i < size; i++) {
 378                 buffer[0] = *hex++;
 379                 buffer[1] = *hex++;
 380
 381                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 382
 383                 if (endp != &buffer[2])
 384                         return -EINVAL;
 385         }
 386
 387         if (*hex != '\0')
 388                 return -EINVAL;
 389
 390         return 0;
 391 }
 392
 393 /*
 394  * Encode key into its hex representation
 395  */
 396 static void crypt_encode_key(char *hex, u8 *key, int size)
 397 {
 398         int i;
 399
 400         for(i = 0; i < size; i++) {
 401                 sprintf(hex, "%02x", *key);
 402                 hex += 2;
 403                 key++;
 404         }
 405 }
 406
 407 /*
 408  * Construct an encryption mapping:
 409  * <cipher> <key> <iv_offset> <dev_path> <start>
 410  */
 411 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 412 {
 413         struct crypt_config *cc;
 414         struct crypto_tfm *tfm;
 415         char *tmp;
 416         char *cipher;
 417         char *mode;
 418         int crypto_flags;
 419         int key_size;
 420
 421         if (argc != 5) {
 422                 ti->error = PFX "Not enough arguments";
 423                 return -EINVAL;
 424         }
 425
 426         tmp = argv[0];
 427         cipher = strsep(&tmp, "-");
 428         mode = strsep(&tmp, "-");
 429
 430         if (tmp)
 431                 DMWARN(PFX "Unexpected additional cipher options");
 432
 433         key_size = strlen(argv[1]) >> 1;
 434
 435         cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 436         if (cc == NULL) {
 437                 ti->error =
 438                         PFX "Cannot allocate transparent encryption context";
 439                 return -ENOMEM;
 440         }
 441
 442         if (!mode || strcmp(mode, "plain") == 0)
 443                 cc->iv_generator = crypt_iv_plain;
 444         else if (strcmp(mode, "ecb") == 0)
 445                 cc->iv_generator = NULL;
 446         else {
 447                 ti->error = PFX "Invalid chaining mode";
 448                 goto bad1;
 449         }
 450
 451         if (cc->iv_generator)
 452                 crypto_flags = CRYPTO_TFM_MODE_CBC;
 453         else
 454                 crypto_flags = CRYPTO_TFM_MODE_ECB;
 455
 456         tfm = crypto_alloc_tfm(cipher, crypto_flags);
 457         if (!tfm) {
 458                 ti->error = PFX "Error allocating crypto tfm";
 459                 goto bad1;
 460         }
 461         if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) {
 462                 ti->error = PFX "Expected cipher algorithm";
 463                 goto bad2;
 464         }
 465
 466         if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv)
 467                 /* at least a 32 bit sector number should fit in our buffer */
 468                 cc->iv_size = max(crypto_tfm_alg_ivsize(tfm),
 469                                   (unsigned int)(sizeof(u32) / sizeof(u8)));
 470         else {
 471                 cc->iv_size = 0;
 472                 if (cc->iv_generator) {
 473                         DMWARN(PFX "Selected cipher does not support IVs");
 474                         cc->iv_generator = NULL;
 475                 }
 476         }
 477
 478         cc->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
 479                                      mempool_free_slab, _crypt_io_pool);
 480         if (!cc->io_pool) {
 481                 ti->error = PFX "Cannot allocate crypt io mempool";
 482                 goto bad2;
 483         }
 484
 485         cc->page_pool = mempool_create(MIN_POOL_PAGES, mempool_alloc_page,
 486                                        mempool_free_page, NULL);
 487         if (!cc->page_pool) {
 488                 ti->error = PFX "Cannot allocate page mempool";
 489                 goto bad3;
 490         }
 491
 492         cc->tfm = tfm;
 493         cc->key_size = key_size;
 494         if ((key_size == 0 && strcmp(argv[1], "-") != 0)
 495             || crypt_decode_key(cc->key, argv[1], key_size) < 0) {
 496                 ti->error = PFX "Error decoding key";
 497                 goto bad4;
 498         }
 499
 500         if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) {
 501                 ti->error = PFX "Error setting key";
 502                 goto bad4;
 503         }
 504
 505         if (sscanf(argv[2], SECTOR_FORMAT, &cc->iv_offset) != 1) {
 506                 ti->error = PFX "Invalid iv_offset sector";
 507                 goto bad4;
 508         }
 509
 510         if (sscanf(argv[4], SECTOR_FORMAT, &cc->start) != 1) {
 511                 ti->error = PFX "Invalid device sector";
 512                 goto bad4;
 513         }
 514
 515         if (dm_get_device(ti, argv[3], cc->start, ti->len,
 516                           dm_table_get_mode(ti->table), &cc->dev)) {
 517                 ti->error = PFX "Device lookup failed";
 518                 goto bad4;
 519         }
 520
 521         ti->private = cc;
 522         return 0;
 523
 524 bad4:
 525         mempool_destroy(cc->page_pool);
 526 bad3:
 527         mempool_destroy(cc->io_pool);
 528 bad2:
 529         crypto_free_tfm(tfm);
 530 bad1:
 531         kfree(cc);
 532         return -EINVAL;
 533 }
 534
 535 static void crypt_dtr(struct dm_target *ti)
 536 {
 537         struct crypt_config *cc = (struct crypt_config *) ti->private;
 538
 539         mempool_destroy(cc->page_pool);
 540         mempool_destroy(cc->io_pool);
 541
 542         crypto_free_tfm(cc->tfm);
 543         dm_put_device(ti, cc->dev);
 544         kfree(cc);
 545 }
 546
 547 static int crypt_endio(struct bio *bio, unsigned int done, int error)
 548 {
 549         struct crypt_io *io = (struct crypt_io *) bio->bi_private;
 550         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 551
 552         if (bio_data_dir(bio) == WRITE) {
 553                 /*
 554                  * free the processed pages, even if
 555                  * it's only a partially completed write
 556                  */
 557                 crypt_free_buffer_pages(cc, bio, done);
 558         }
 559
 560         if (bio->bi_size)
 561                 return 1;
 562
 563         bio_put(bio);
 564
 565         /*
 566          * successful reads are decrypted by the worker thread
 567          */
 568         if ((bio_data_dir(bio) == READ)
 569             && bio_flagged(bio, BIO_UPTODATE)) {
 570                 kcryptd_queue_io(io);
 571                 return 0;
 572         }
 573
 574         dec_pending(io, error);
 575         return error;
 576 }
 577
 578 static inline struct bio *
 579 crypt_clone(struct crypt_config *cc, struct crypt_io *io, struct bio *bio,
 580             sector_t sector, int *bvec_idx, struct convert_context *ctx)
 581 {
 582         struct bio *clone;
 583
 584         if (bio_data_dir(bio) == WRITE) {
 585                 clone = crypt_alloc_buffer(cc, bio->bi_size,
 586                                  io->first_clone, bvec_idx);
 587                 if (clone) {
 588                         ctx->bio_out = clone;
 589                         if (crypt_convert(cc, ctx) < 0) {
 590                                 crypt_free_buffer_pages(cc, clone,
 591                                                         clone->bi_size);
 592                                 bio_put(clone);
 593                                 return NULL;
 594                         }
 595                 }
 596         } else {
 597                 /*
 598                  * The block layer might modify the bvec array, so always
 599                  * copy the required bvecs because we need the original
 600                  * one in order to decrypt the whole bio data *afterwards*.
 601                  */
 602                 clone = bio_alloc(GFP_NOIO, bio_segments(bio));
 603                 if (clone) {
 604                         clone->bi_idx = 0;
 605                         clone->bi_vcnt = bio_segments(bio);
 606                         clone->bi_size = bio->bi_size;
 607                         memcpy(clone->bi_io_vec, bio_iovec(bio),
 608                                sizeof(struct bio_vec) * clone->bi_vcnt);
 609                 }
 610         }
 611
 612         if (!clone)
 613                 return NULL;
 614
 615         clone->bi_private = io;
 616         clone->bi_end_io = crypt_endio;
 617         clone->bi_bdev = cc->dev->bdev;
 618         clone->bi_sector = cc->start + sector;
 619         clone->bi_rw = bio->bi_rw;
 620
 621         return clone;
 622 }
 623
 624 static int crypt_map(struct dm_target *ti, struct bio *bio,
 625                      union map_info *map_context)
 626 {
 627         struct crypt_config *cc = (struct crypt_config *) ti->private;
 628         struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO);
 629         struct convert_context ctx;
 630         struct bio *clone;
 631         unsigned int remaining = bio->bi_size;
 632         sector_t sector = bio->bi_sector - ti->begin;
 633         int bvec_idx = 0;
 634
 635         io->target = ti;
 636         io->bio = bio;
 637         io->first_clone = NULL;
 638         io->error = 0;
 639         atomic_set(&io->pending, 1); /* hold a reference */
 640
 641         if (bio_data_dir(bio) == WRITE)
 642                 crypt_convert_init(cc, &ctx, NULL, bio, sector, 1);
 643
 644         /*
 645          * The allocated buffers can be smaller than the whole bio,
 646          * so repeat the whole process until all the data can be handled.
 647          */
 648         while (remaining) {
 649                 clone = crypt_clone(cc, io, bio, sector, &bvec_idx, &ctx);
 650                 if (!clone)
 651                         goto cleanup;
 652
 653                 if (!io->first_clone) {
 654                         /*
 655                          * hold a reference to the first clone, because it
 656                          * holds the bio_vec array and that can't be freed
 657                          * before all other clones are released
 658                          */
 659                         bio_get(clone);
 660                         io->first_clone = clone;
 661                 }
 662                 atomic_inc(&io->pending);
 663
 664                 remaining -= clone->bi_size;
 665                 sector += bio_sectors(clone);
 666
 667                 generic_make_request(clone);
 668
 669                 /* out of memory -> run queues */
 670                 if (remaining)
 671                         blk_congestion_wait(bio_data_dir(clone), HZ/100);
 672         }
 673
 674         /* drop reference, clones could have returned before we reach this */
 675         dec_pending(io, 0);
 676         return 0;
 677
 678 cleanup:
 679         if (io->first_clone) {
 680                 dec_pending(io, -ENOMEM);
 681                 return 0;
 682         }
 683
 684         /* if no bio has been dispatched yet, we can directly return the error */
 685         mempool_free(io, cc->io_pool);
 686         return -ENOMEM;
 687 }
 688
 689 static int crypt_status(struct dm_target *ti, status_type_t type,
 690                         char *result, unsigned int maxlen)
 691 {
 692         struct crypt_config *cc = (struct crypt_config *) ti->private;
 693         char buffer[32];
 694         const char *cipher;
 695         const char *mode = NULL;
 696         int offset;
 697
 698         switch (type) {
 699         case STATUSTYPE_INFO:
 700                 result[0] = '\0';
 701                 break;
 702
 703         case STATUSTYPE_TABLE:
 704                 cipher = crypto_tfm_alg_name(cc->tfm);
 705
 706                 switch(cc->tfm->crt_cipher.cit_mode) {
 707                 case CRYPTO_TFM_MODE_CBC:
 708                         mode = "plain";
 709                         break;
 710                 case CRYPTO_TFM_MODE_ECB:
 711                         mode = "ecb";
 712                         break;
 713                 default:
 714                         BUG();
 715                 }
 716
 717                 snprintf(result, maxlen, "%s-%s ", cipher, mode);
 718                 offset = strlen(result);
 719
 720                 if (cc->key_size > 0) {
 721                         if ((maxlen - offset) < ((cc->key_size << 1) + 1))
 722                                 return -ENOMEM;
 723
 724                         crypt_encode_key(result + offset, cc->key, cc->key_size);
 725                         offset += cc->key_size << 1;
 726                 } else {
 727                         if (offset >= maxlen)
 728                                 return -ENOMEM;
 729                         result[offset++] = '-';
 730                 }
 731
 732                 format_dev_t(buffer, cc->dev->bdev->bd_dev);
 733                 snprintf(result + offset, maxlen - offset, " " SECTOR_FORMAT
 734                          " %s " SECTOR_FORMAT, cc->iv_offset,
 735                          buffer, cc->start);
 736                 break;
 737         }
 738         return 0;
 739 }
 740
 741 static struct target_type crypt_target = {
 742         .name   = "crypt",
 743         .version= {1, 0, 0},
 744         .module = THIS_MODULE,
 745         .ctr    = crypt_ctr,
 746         .dtr    = crypt_dtr,
 747         .map    = crypt_map,
 748         .status = crypt_status,
 749 };
 750
 751 static int __init dm_crypt_init(void)
 752 {
 753         int r;
 754
 755         _crypt_io_pool = kmem_cache_create("dm-crypt_io",
 756                                            sizeof(struct crypt_io),
 757                                            0, 0, NULL, NULL);
 758         if (!_crypt_io_pool)
 759                 return -ENOMEM;
 760
 761         _kcryptd_workqueue = create_workqueue("kcryptd");
 762         if (!_kcryptd_workqueue) {
 763                 r = -ENOMEM;
 764                 DMERR(PFX "couldn't create kcryptd");
 765                 goto bad1;
 766         }
 767
 768         r = dm_register_target(&crypt_target);
 769         if (r < 0) {
 770                 DMERR(PFX "register failed %d", r);
 771                 goto bad2;
 772         }
 773
 774         return 0;
 775
 776 bad2:
 777         destroy_workqueue(_kcryptd_workqueue);
 778 bad1:
 779         kmem_cache_destroy(_crypt_io_pool);
 780         return r;
 781 }
 782
 783 static void __exit dm_crypt_exit(void)
 784 {
 785         int r = dm_unregister_target(&crypt_target);
 786
 787         if (r < 0)
 788                 DMERR(PFX "unregister failed %d", r);
 789
 790         destroy_workqueue(_kcryptd_workqueue);
 791         kmem_cache_destroy(_crypt_io_pool);
 792 }
 793
 794 module_init(dm_crypt_init);
 795 module_exit(dm_crypt_exit);
 796
 797 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
 798 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
 799 MODULE_LICENSE("GPL");