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  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/kernel.h>
  11 #include <linux/bio.h>
  12 #include <linux/blkdev.h>
  13 #include <linux/mempool.h>
  14 #include <linux/slab.h>
  15 #include <linux/crypto.h>
  16 #include <linux/workqueue.h>
  17 #include <asm/atomic.h>
  18 #include <linux/scatterlist.h>
  19 #include <asm/page.h>
  20
  21 #include "dm.h"
  22
  23 #define PFX     "crypt: "
  24
  25 /*
  26  * per bio private data
  27  */
  28 struct crypt_io {
  29         struct dm_target *target;
  30         struct bio *bio;
  31         struct bio *first_clone;
  32         struct work_struct work;
  33         atomic_t pending;
  34         int error;
  35 };
  36
  37 /*
  38  * context holding the current state of a multi-part conversion
  39  */
  40 struct convert_context {
  41         struct bio *bio_in;
  42         struct bio *bio_out;
  43         unsigned int offset_in;
  44         unsigned int offset_out;
  45         unsigned int idx_in;
  46         unsigned int idx_out;
  47         sector_t sector;
  48         int write;
  49 };
  50
  51 struct crypt_config;
  52
  53 struct crypt_iv_operations {
  54         int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
  55                    const char *opts);
  56         void (*dtr)(struct crypt_config *cc);
  57         const char *(*status)(struct crypt_config *cc);
  58         int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
  59 };
  60
  61 /*
  62  * Crypt: maps a linear range of a block device
  63  * and encrypts / decrypts at the same time.
  64  */
  65 struct crypt_config {
  66         struct dm_dev *dev;
  67         sector_t start;
  68
  69         /*
  70          * pool for per bio private data and
  71          * for encryption buffer pages
  72          */
  73         mempool_t *io_pool;
  74         mempool_t *page_pool;
  75
  76         /*
  77          * crypto related data
  78          */
  79         struct crypt_iv_operations *iv_gen_ops;
  80         char *iv_mode;
  81         void *iv_gen_private;
  82         sector_t iv_offset;
  83         unsigned int iv_size;
  84
  85         struct crypto_tfm *tfm;
  86         unsigned int key_size;
  87         u8 key[0];
  88 };
  89
  90 #define MIN_IOS        256
  91 #define MIN_POOL_PAGES 32
  92 #define MIN_BIO_PAGES  8
  93
  94 static kmem_cache_t *_crypt_io_pool;
  95
  96 /*
  97  * Different IV generation algorithms:
  98  *
  99  * plain: the initial vector is the 32-bit low-endian version of the sector
 100  *        number, padded with zeros if neccessary.
 101  *
 102  * ess_iv: "encrypted sector|salt initial vector", the sector number is
 103  *         encrypted with the bulk cipher using a salt as key. The salt
 104  *         should be derived from the bulk cipher's key via hashing.
 105  *
 106  * plumb: unimplemented, see:
 107  * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 108  */
 109
 110 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 111 {
 112         memset(iv, 0, cc->iv_size);
 113         *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
 114
 115         return 0;
 116 }
 117
 118 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 119                               const char *opts)
 120 {
 121         struct crypto_tfm *essiv_tfm;
 122         struct crypto_tfm *hash_tfm;
 123         struct scatterlist sg;
 124         unsigned int saltsize;
 125         u8 *salt;
 126
 127         if (opts == NULL) {
 128                 ti->error = PFX "Digest algorithm missing for ESSIV mode";
 129                 return -EINVAL;
 130         }
 131
 132         /* Hash the cipher key with the given hash algorithm */
 133         hash_tfm = crypto_alloc_tfm(opts, CRYPTO_TFM_REQ_MAY_SLEEP);
 134         if (hash_tfm == NULL) {
 135                 ti->error = PFX "Error initializing ESSIV hash";
 136                 return -EINVAL;
 137         }
 138
 139         if (crypto_tfm_alg_type(hash_tfm) != CRYPTO_ALG_TYPE_DIGEST) {
 140                 ti->error = PFX "Expected digest algorithm for ESSIV hash";
 141                 crypto_free_tfm(hash_tfm);
 142                 return -EINVAL;
 143         }
 144
 145         saltsize = crypto_tfm_alg_digestsize(hash_tfm);
 146         salt = kmalloc(saltsize, GFP_KERNEL);
 147         if (salt == NULL) {
 148                 ti->error = PFX "Error kmallocing salt storage in ESSIV";
 149                 crypto_free_tfm(hash_tfm);
 150                 return -ENOMEM;
 151         }
 152
 153         sg_set_buf(&sg, cc->key, cc->key_size);
 154         crypto_digest_digest(hash_tfm, &sg, 1, salt);
 155         crypto_free_tfm(hash_tfm);
 156
 157         /* Setup the essiv_tfm with the given salt */
 158         essiv_tfm = crypto_alloc_tfm(crypto_tfm_alg_name(cc->tfm),
 159                                      CRYPTO_TFM_MODE_ECB |
 160                                      CRYPTO_TFM_REQ_MAY_SLEEP);
 161         if (essiv_tfm == NULL) {
 162                 ti->error = PFX "Error allocating crypto tfm for ESSIV";
 163                 kfree(salt);
 164                 return -EINVAL;
 165         }
 166         if (crypto_tfm_alg_blocksize(essiv_tfm)
 167             != crypto_tfm_alg_ivsize(cc->tfm)) {
 168                 ti->error = PFX "Block size of ESSIV cipher does "
 169                                 "not match IV size of block cipher";
 170                 crypto_free_tfm(essiv_tfm);
 171                 kfree(salt);
 172                 return -EINVAL;
 173         }
 174         if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) {
 175                 ti->error = PFX "Failed to set key for ESSIV cipher";
 176                 crypto_free_tfm(essiv_tfm);
 177                 kfree(salt);
 178                 return -EINVAL;
 179         }
 180         kfree(salt);
 181
 182         cc->iv_gen_private = (void *)essiv_tfm;
 183         return 0;
 184 }
 185
 186 static void crypt_iv_essiv_dtr(struct crypt_config *cc)
 187 {
 188         crypto_free_tfm((struct crypto_tfm *)cc->iv_gen_private);
 189         cc->iv_gen_private = NULL;
 190 }
 191
 192 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 193 {
 194         struct scatterlist sg;
 195
 196         memset(iv, 0, cc->iv_size);
 197         *(u64 *)iv = cpu_to_le64(sector);
 198
 199         sg_set_buf(&sg, iv, cc->iv_size);
 200         crypto_cipher_encrypt((struct crypto_tfm *)cc->iv_gen_private,
 201                               &sg, &sg, cc->iv_size);
 202
 203         return 0;
 204 }
 205
 206 static struct crypt_iv_operations crypt_iv_plain_ops = {
 207         .generator = crypt_iv_plain_gen
 208 };
 209
 210 static struct crypt_iv_operations crypt_iv_essiv_ops = {
 211         .ctr       = crypt_iv_essiv_ctr,
 212         .dtr       = crypt_iv_essiv_dtr,
 213         .generator = crypt_iv_essiv_gen
 214 };
 215
 216
 217 static int
 218 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
 219                           struct scatterlist *in, unsigned int length,
 220                           int write, sector_t sector)
 221 {
 222         u8 iv[cc->iv_size];
 223         int r;
 224
 225         if (cc->iv_gen_ops) {
 226                 r = cc->iv_gen_ops->generator(cc, iv, sector);
 227                 if (r < 0)
 228                         return r;
 229
 230                 if (write)
 231                         r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv);
 232                 else
 233                         r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv);
 234         } else {
 235                 if (write)
 236                         r = crypto_cipher_encrypt(cc->tfm, out, in, length);
 237                 else
 238                         r = crypto_cipher_decrypt(cc->tfm, out, in, length);
 239         }
 240
 241         return r;
 242 }
 243
 244 static void
 245 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
 246                    struct bio *bio_out, struct bio *bio_in,
 247                    sector_t sector, int write)
 248 {
 249         ctx->bio_in = bio_in;
 250         ctx->bio_out = bio_out;
 251         ctx->offset_in = 0;
 252         ctx->offset_out = 0;
 253         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
 254         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
 255         ctx->sector = sector + cc->iv_offset;
 256         ctx->write = write;
 257 }
 258
 259 /*
 260  * Encrypt / decrypt data from one bio to another one (can be the same one)
 261  */
 262 static int crypt_convert(struct crypt_config *cc,
 263                          struct convert_context *ctx)
 264 {
 265         int r = 0;
 266
 267         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 268               ctx->idx_out < ctx->bio_out->bi_vcnt) {
 269                 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 270                 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 271                 struct scatterlist sg_in = {
 272                         .page = bv_in->bv_page,
 273                         .offset = bv_in->bv_offset + ctx->offset_in,
 274                         .length = 1 << SECTOR_SHIFT
 275                 };
 276                 struct scatterlist sg_out = {
 277                         .page = bv_out->bv_page,
 278                         .offset = bv_out->bv_offset + ctx->offset_out,
 279                         .length = 1 << SECTOR_SHIFT
 280                 };
 281
 282                 ctx->offset_in += sg_in.length;
 283                 if (ctx->offset_in >= bv_in->bv_len) {
 284                         ctx->offset_in = 0;
 285                         ctx->idx_in++;
 286                 }
 287
 288                 ctx->offset_out += sg_out.length;
 289                 if (ctx->offset_out >= bv_out->bv_len) {
 290                         ctx->offset_out = 0;
 291                         ctx->idx_out++;
 292                 }
 293
 294                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 295                                               ctx->write, ctx->sector);
 296                 if (r < 0)
 297                         break;
 298
 299                 ctx->sector++;
 300         }
 301
 302         return r;
 303 }
 304
 305 /*
 306  * Generate a new unfragmented bio with the given size
 307  * This should never violate the device limitations
 308  * May return a smaller bio when running out of pages
 309  */
 310 static struct bio *
 311 crypt_alloc_buffer(struct crypt_config *cc, unsigned int size,
 312                    struct bio *base_bio, unsigned int *bio_vec_idx)
 313 {
 314         struct bio *bio;
 315         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 316         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 317         unsigned int i;
 318
 319         /*
 320          * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and
 321          * to fail earlier.  This is not necessary but increases throughput.
 322          * FIXME: Is this really intelligent?
 323          */
 324         if (base_bio)
 325                 bio = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC);
 326         else
 327                 bio = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs);
 328         if (!bio)
 329                 return NULL;
 330
 331         /* if the last bio was not complete, continue where that one ended */
 332         bio->bi_idx = *bio_vec_idx;
 333         bio->bi_vcnt = *bio_vec_idx;
 334         bio->bi_size = 0;
 335         bio->bi_flags &= ~(1 << BIO_SEG_VALID);
 336
 337         /* bio->bi_idx pages have already been allocated */
 338         size -= bio->bi_idx * PAGE_SIZE;
 339
 340         for(i = bio->bi_idx; i < nr_iovecs; i++) {
 341                 struct bio_vec *bv = bio_iovec_idx(bio, i);
 342
 343                 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
 344                 if (!bv->bv_page)
 345                         break;
 346
 347                 /*
 348                  * if additional pages cannot be allocated without waiting,
 349                  * return a partially allocated bio, the caller will then try
 350                  * to allocate additional bios while submitting this partial bio
 351                  */
 352                 if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1))
 353                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 354
 355                 bv->bv_offset = 0;
 356                 if (size > PAGE_SIZE)
 357                         bv->bv_len = PAGE_SIZE;
 358                 else
 359                         bv->bv_len = size;
 360
 361                 bio->bi_size += bv->bv_len;
 362                 bio->bi_vcnt++;
 363                 size -= bv->bv_len;
 364         }
 365
 366         if (!bio->bi_size) {
 367                 bio_put(bio);
 368                 return NULL;
 369         }
 370
 371         /*
 372          * Remember the last bio_vec allocated to be able
 373          * to correctly continue after the splitting.
 374          */
 375         *bio_vec_idx = bio->bi_vcnt;
 376
 377         return bio;
 378 }
 379
 380 static void crypt_free_buffer_pages(struct crypt_config *cc,
 381                                     struct bio *bio, unsigned int bytes)
 382 {
 383         unsigned int i, start, end;
 384         struct bio_vec *bv;
 385
 386         /*
 387          * This is ugly, but Jens Axboe thinks that using bi_idx in the
 388          * endio function is too dangerous at the moment, so I calculate the
 389          * correct position using bi_vcnt and bi_size.
 390          * The bv_offset and bv_len fields might already be modified but we
 391          * know that we always allocated whole pages.
 392          * A fix to the bi_idx issue in the kernel is in the works, so
 393          * we will hopefully be able to revert to the cleaner solution soon.
 394          */
 395         i = bio->bi_vcnt - 1;
 396         bv = bio_iovec_idx(bio, i);
 397         end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size;
 398         start = end - bytes;
 399
 400         start >>= PAGE_SHIFT;
 401         if (!bio->bi_size)
 402                 end = bio->bi_vcnt;
 403         else
 404                 end >>= PAGE_SHIFT;
 405
 406         for(i = start; i < end; i++) {
 407                 bv = bio_iovec_idx(bio, i);
 408                 BUG_ON(!bv->bv_page);
 409                 mempool_free(bv->bv_page, cc->page_pool);
 410                 bv->bv_page = NULL;
 411         }
 412 }
 413
 414 /*
 415  * One of the bios was finished. Check for completion of
 416  * the whole request and correctly clean up the buffer.
 417  */
 418 static void dec_pending(struct crypt_io *io, int error)
 419 {
 420         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 421
 422         if (error < 0)
 423                 io->error = error;
 424
 425         if (!atomic_dec_and_test(&io->pending))
 426                 return;
 427
 428         if (io->first_clone)
 429                 bio_put(io->first_clone);
 430
 431         bio_endio(io->bio, io->bio->bi_size, io->error);
 432
 433         mempool_free(io, cc->io_pool);
 434 }
 435
 436 /*
 437  * kcryptd:
 438  *
 439  * Needed because it would be very unwise to do decryption in an
 440  * interrupt context, so bios returning from read requests get
 441  * queued here.
 442  */
 443 static struct workqueue_struct *_kcryptd_workqueue;
 444
 445 static void kcryptd_do_work(void *data)
 446 {
 447         struct crypt_io *io = (struct crypt_io *) data;
 448         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 449         struct convert_context ctx;
 450         int r;
 451
 452         crypt_convert_init(cc, &ctx, io->bio, io->bio,
 453                            io->bio->bi_sector - io->target->begin, 0);
 454         r = crypt_convert(cc, &ctx);
 455
 456         dec_pending(io, r);
 457 }
 458
 459 static void kcryptd_queue_io(struct crypt_io *io)
 460 {
 461         INIT_WORK(&io->work, kcryptd_do_work, io);
 462         queue_work(_kcryptd_workqueue, &io->work);
 463 }
 464
 465 /*
 466  * Decode key from its hex representation
 467  */
 468 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 469 {
 470         char buffer[3];
 471         char *endp;
 472         unsigned int i;
 473
 474         buffer[2] = '\0';
 475
 476         for(i = 0; i < size; i++) {
 477                 buffer[0] = *hex++;
 478                 buffer[1] = *hex++;
 479
 480                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 481
 482                 if (endp != &buffer[2])
 483                         return -EINVAL;
 484         }
 485
 486         if (*hex != '\0')
 487                 return -EINVAL;
 488
 489         return 0;
 490 }
 491
 492 /*
 493  * Encode key into its hex representation
 494  */
 495 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
 496 {
 497         unsigned int i;
 498
 499         for(i = 0; i < size; i++) {
 500                 sprintf(hex, "%02x", *key);
 501                 hex += 2;
 502                 key++;
 503         }
 504 }
 505
 506 /*
 507  * Construct an encryption mapping:
 508  * <cipher> <key> <iv_offset> <dev_path> <start>
 509  */
 510 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 511 {
 512         struct crypt_config *cc;
 513         struct crypto_tfm *tfm;
 514         char *tmp;
 515         char *cipher;
 516         char *chainmode;
 517         char *ivmode;
 518         char *ivopts;
 519         unsigned int crypto_flags;
 520         unsigned int key_size;
 521         unsigned long long tmpll;
 522
 523         if (argc != 5) {
 524                 ti->error = PFX "Not enough arguments";
 525                 return -EINVAL;
 526         }
 527
 528         tmp = argv[0];
 529         cipher = strsep(&tmp, "-");
 530         chainmode = strsep(&tmp, "-");
 531         ivopts = strsep(&tmp, "-");
 532         ivmode = strsep(&ivopts, ":");
 533
 534         if (tmp)
 535                 DMWARN(PFX "Unexpected additional cipher options");
 536
 537         key_size = strlen(argv[1]) >> 1;
 538
 539         cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 540         if (cc == NULL) {
 541                 ti->error =
 542                         PFX "Cannot allocate transparent encryption context";
 543                 return -ENOMEM;
 544         }
 545
 546         cc->key_size = key_size;
 547         if ((!key_size && strcmp(argv[1], "-") != 0) ||
 548             (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) {
 549                 ti->error = PFX "Error decoding key";
 550                 goto bad1;
 551         }
 552
 553         /* Compatiblity mode for old dm-crypt cipher strings */
 554         if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 555                 chainmode = "cbc";
 556                 ivmode = "plain";
 557         }
 558
 559         /* Choose crypto_flags according to chainmode */
 560         if (strcmp(chainmode, "cbc") == 0)
 561                 crypto_flags = CRYPTO_TFM_MODE_CBC;
 562         else if (strcmp(chainmode, "ecb") == 0)
 563                 crypto_flags = CRYPTO_TFM_MODE_ECB;
 564         else {
 565                 ti->error = PFX "Unknown chaining mode";
 566                 goto bad1;
 567         }
 568
 569         if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) {
 570                 ti->error = PFX "This chaining mode requires an IV mechanism";
 571                 goto bad1;
 572         }
 573
 574         tfm = crypto_alloc_tfm(cipher, crypto_flags | CRYPTO_TFM_REQ_MAY_SLEEP);
 575         if (!tfm) {
 576                 ti->error = PFX "Error allocating crypto tfm";
 577                 goto bad1;
 578         }
 579         if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) {
 580                 ti->error = PFX "Expected cipher algorithm";
 581                 goto bad2;
 582         }
 583
 584         cc->tfm = tfm;
 585
 586         /*
 587          * Choose ivmode. Valid modes: "plain", "essiv:<esshash>".
 588          * See comments at iv code
 589          */
 590
 591         if (ivmode == NULL)
 592                 cc->iv_gen_ops = NULL;
 593         else if (strcmp(ivmode, "plain") == 0)
 594                 cc->iv_gen_ops = &crypt_iv_plain_ops;
 595         else if (strcmp(ivmode, "essiv") == 0)
 596                 cc->iv_gen_ops = &crypt_iv_essiv_ops;
 597         else {
 598                 ti->error = PFX "Invalid IV mode";
 599                 goto bad2;
 600         }
 601
 602         if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
 603             cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
 604                 goto bad2;
 605
 606         if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv)
 607                 /* at least a 64 bit sector number should fit in our buffer */
 608                 cc->iv_size = max(crypto_tfm_alg_ivsize(tfm),
 609                                   (unsigned int)(sizeof(u64) / sizeof(u8)));
 610         else {
 611                 cc->iv_size = 0;
 612                 if (cc->iv_gen_ops) {
 613                         DMWARN(PFX "Selected cipher does not support IVs");
 614                         if (cc->iv_gen_ops->dtr)
 615                                 cc->iv_gen_ops->dtr(cc);
 616                         cc->iv_gen_ops = NULL;
 617                 }
 618         }
 619
 620         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
 621         if (!cc->io_pool) {
 622                 ti->error = PFX "Cannot allocate crypt io mempool";
 623                 goto bad3;
 624         }
 625
 626         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
 627         if (!cc->page_pool) {
 628                 ti->error = PFX "Cannot allocate page mempool";
 629                 goto bad4;
 630         }
 631
 632         if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) {
 633                 ti->error = PFX "Error setting key";
 634                 goto bad5;
 635         }
 636
 637         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 638                 ti->error = PFX "Invalid iv_offset sector";
 639                 goto bad5;
 640         }
 641         cc->iv_offset = tmpll;
 642
 643         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
 644                 ti->error = PFX "Invalid device sector";
 645                 goto bad5;
 646         }
 647         cc->start = tmpll;
 648
 649         if (dm_get_device(ti, argv[3], cc->start, ti->len,
 650                           dm_table_get_mode(ti->table), &cc->dev)) {
 651                 ti->error = PFX "Device lookup failed";
 652                 goto bad5;
 653         }
 654
 655         if (ivmode && cc->iv_gen_ops) {
 656                 if (ivopts)
 657                         *(ivopts - 1) = ':';
 658                 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
 659                 if (!cc->iv_mode) {
 660                         ti->error = PFX "Error kmallocing iv_mode string";
 661                         goto bad5;
 662                 }
 663                 strcpy(cc->iv_mode, ivmode);
 664         } else
 665                 cc->iv_mode = NULL;
 666
 667         ti->private = cc;
 668         return 0;
 669
 670 bad5:
 671         mempool_destroy(cc->page_pool);
 672 bad4:
 673         mempool_destroy(cc->io_pool);
 674 bad3:
 675         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 676                 cc->iv_gen_ops->dtr(cc);
 677 bad2:
 678         crypto_free_tfm(tfm);
 679 bad1:
 680         /* Must zero key material before freeing */
 681         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 682         kfree(cc);
 683         return -EINVAL;
 684 }
 685
 686 static void crypt_dtr(struct dm_target *ti)
 687 {
 688         struct crypt_config *cc = (struct crypt_config *) ti->private;
 689
 690         mempool_destroy(cc->page_pool);
 691         mempool_destroy(cc->io_pool);
 692
 693         kfree(cc->iv_mode);
 694         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 695                 cc->iv_gen_ops->dtr(cc);
 696         crypto_free_tfm(cc->tfm);
 697         dm_put_device(ti, cc->dev);
 698
 699         /* Must zero key material before freeing */
 700         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 701         kfree(cc);
 702 }
 703
 704 static int crypt_endio(struct bio *bio, unsigned int done, int error)
 705 {
 706         struct crypt_io *io = (struct crypt_io *) bio->bi_private;
 707         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 708
 709         if (bio_data_dir(bio) == WRITE) {
 710                 /*
 711                  * free the processed pages, even if
 712                  * it's only a partially completed write
 713                  */
 714                 crypt_free_buffer_pages(cc, bio, done);
 715         }
 716
 717         if (bio->bi_size)
 718                 return 1;
 719
 720         bio_put(bio);
 721
 722         /*
 723          * successful reads are decrypted by the worker thread
 724          */
 725         if ((bio_data_dir(bio) == READ)
 726             && bio_flagged(bio, BIO_UPTODATE)) {
 727                 kcryptd_queue_io(io);
 728                 return 0;
 729         }
 730
 731         dec_pending(io, error);
 732         return error;
 733 }
 734
 735 static inline struct bio *
 736 crypt_clone(struct crypt_config *cc, struct crypt_io *io, struct bio *bio,
 737             sector_t sector, unsigned int *bvec_idx,
 738             struct convert_context *ctx)
 739 {
 740         struct bio *clone;
 741
 742         if (bio_data_dir(bio) == WRITE) {
 743                 clone = crypt_alloc_buffer(cc, bio->bi_size,
 744                                  io->first_clone, bvec_idx);
 745                 if (clone) {
 746                         ctx->bio_out = clone;
 747                         if (crypt_convert(cc, ctx) < 0) {
 748                                 crypt_free_buffer_pages(cc, clone,
 749                                                         clone->bi_size);
 750                                 bio_put(clone);
 751                                 return NULL;
 752                         }
 753                 }
 754         } else {
 755                 /*
 756                  * The block layer might modify the bvec array, so always
 757                  * copy the required bvecs because we need the original
 758                  * one in order to decrypt the whole bio data *afterwards*.
 759                  */
 760                 clone = bio_alloc(GFP_NOIO, bio_segments(bio));
 761                 if (clone) {
 762                         clone->bi_idx = 0;
 763                         clone->bi_vcnt = bio_segments(bio);
 764                         clone->bi_size = bio->bi_size;
 765                         memcpy(clone->bi_io_vec, bio_iovec(bio),
 766                                sizeof(struct bio_vec) * clone->bi_vcnt);
 767                 }
 768         }
 769
 770         if (!clone)
 771                 return NULL;
 772
 773         clone->bi_private = io;
 774         clone->bi_end_io = crypt_endio;
 775         clone->bi_bdev = cc->dev->bdev;
 776         clone->bi_sector = cc->start + sector;
 777         clone->bi_rw = bio->bi_rw;
 778
 779         return clone;
 780 }
 781
 782 static int crypt_map(struct dm_target *ti, struct bio *bio,
 783                      union map_info *map_context)
 784 {
 785         struct crypt_config *cc = (struct crypt_config *) ti->private;
 786         struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO);
 787         struct convert_context ctx;
 788         struct bio *clone;
 789         unsigned int remaining = bio->bi_size;
 790         sector_t sector = bio->bi_sector - ti->begin;
 791         unsigned int bvec_idx = 0;
 792
 793         io->target = ti;
 794         io->bio = bio;
 795         io->first_clone = NULL;
 796         io->error = 0;
 797         atomic_set(&io->pending, 1); /* hold a reference */
 798
 799         if (bio_data_dir(bio) == WRITE)
 800                 crypt_convert_init(cc, &ctx, NULL, bio, sector, 1);
 801
 802         /*
 803          * The allocated buffers can be smaller than the whole bio,
 804          * so repeat the whole process until all the data can be handled.
 805          */
 806         while (remaining) {
 807                 clone = crypt_clone(cc, io, bio, sector, &bvec_idx, &ctx);
 808                 if (!clone)
 809                         goto cleanup;
 810
 811                 if (!io->first_clone) {
 812                         /*
 813                          * hold a reference to the first clone, because it
 814                          * holds the bio_vec array and that can't be freed
 815                          * before all other clones are released
 816                          */
 817                         bio_get(clone);
 818                         io->first_clone = clone;
 819                 }
 820                 atomic_inc(&io->pending);
 821
 822                 remaining -= clone->bi_size;
 823                 sector += bio_sectors(clone);
 824
 825                 generic_make_request(clone);
 826
 827                 /* out of memory -> run queues */
 828                 if (remaining)
 829                         blk_congestion_wait(bio_data_dir(clone), HZ/100);
 830         }
 831
 832         /* drop reference, clones could have returned before we reach this */
 833         dec_pending(io, 0);
 834         return 0;
 835
 836 cleanup:
 837         if (io->first_clone) {
 838                 dec_pending(io, -ENOMEM);
 839                 return 0;
 840         }
 841
 842         /* if no bio has been dispatched yet, we can directly return the error */
 843         mempool_free(io, cc->io_pool);
 844         return -ENOMEM;
 845 }
 846
 847 static int crypt_status(struct dm_target *ti, status_type_t type,
 848                         char *result, unsigned int maxlen)
 849 {
 850         struct crypt_config *cc = (struct crypt_config *) ti->private;
 851         const char *cipher;
 852         const char *chainmode = NULL;
 853         unsigned int sz = 0;
 854
 855         switch (type) {
 856         case STATUSTYPE_INFO:
 857                 result[0] = '\0';
 858                 break;
 859
 860         case STATUSTYPE_TABLE:
 861                 cipher = crypto_tfm_alg_name(cc->tfm);
 862
 863                 switch(cc->tfm->crt_cipher.cit_mode) {
 864                 case CRYPTO_TFM_MODE_CBC:
 865                         chainmode = "cbc";
 866                         break;
 867                 case CRYPTO_TFM_MODE_ECB:
 868                         chainmode = "ecb";
 869                         break;
 870                 default:
 871                         BUG();
 872                 }
 873
 874                 if (cc->iv_mode)
 875                         DMEMIT("%s-%s-%s ", cipher, chainmode, cc->iv_mode);
 876                 else
 877                         DMEMIT("%s-%s ", cipher, chainmode);
 878
 879                 if (cc->key_size > 0) {
 880                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
 881                                 return -ENOMEM;
 882
 883                         crypt_encode_key(result + sz, cc->key, cc->key_size);
 884                         sz += cc->key_size << 1;
 885                 } else {
 886                         if (sz >= maxlen)
 887                                 return -ENOMEM;
 888                         result[sz++] = '-';
 889                 }
 890
 891                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
 892                                 cc->dev->name, (unsigned long long)cc->start);
 893                 break;
 894         }
 895         return 0;
 896 }
 897
 898 static struct target_type crypt_target = {
 899         .name   = "crypt",
 900         .version= {1, 1, 0},
 901         .module = THIS_MODULE,
 902         .ctr    = crypt_ctr,
 903         .dtr    = crypt_dtr,
 904         .map    = crypt_map,
 905         .status = crypt_status,
 906 };
 907
 908 static int __init dm_crypt_init(void)
 909 {
 910         int r;
 911
 912         _crypt_io_pool = kmem_cache_create("dm-crypt_io",
 913                                            sizeof(struct crypt_io),
 914                                            0, 0, NULL, NULL);
 915         if (!_crypt_io_pool)
 916                 return -ENOMEM;
 917
 918         _kcryptd_workqueue = create_workqueue("kcryptd");
 919         if (!_kcryptd_workqueue) {
 920                 r = -ENOMEM;
 921                 DMERR(PFX "couldn't create kcryptd");
 922                 goto bad1;
 923         }
 924
 925         r = dm_register_target(&crypt_target);
 926         if (r < 0) {
 927                 DMERR(PFX "register failed %d", r);
 928                 goto bad2;
 929         }
 930
 931         return 0;
 932
 933 bad2:
 934         destroy_workqueue(_kcryptd_workqueue);
 935 bad1:
 936         kmem_cache_destroy(_crypt_io_pool);
 937         return r;
 938 }
 939
 940 static void __exit dm_crypt_exit(void)
 941 {
 942         int r = dm_unregister_target(&crypt_target);
 943
 944         if (r < 0)
 945                 DMERR(PFX "unregister failed %d", r);
 946
 947         destroy_workqueue(_kcryptd_workqueue);
 948         kmem_cache_destroy(_crypt_io_pool);
 949 }
 950
 951 module_init(dm_crypt_init);
 952 module_exit(dm_crypt_exit);
 953
 954 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
 955 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
 956 MODULE_LICENSE("GPL");