drivers/md/dm-crypt.c

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