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