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