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