drivers/md/dm-crypt.c

   1 /*
   2  * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
   3  * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
   4  * Copyright (C) 2006 Red Hat, Inc. All rights reserved.
   5  *
   6  * This file is released under the GPL.
   7  */
   8
   9 #include <linux/err.h>
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/bio.h>
  14 #include <linux/blkdev.h>
  15 #include <linux/mempool.h>
  16 #include <linux/slab.h>
  17 #include <linux/crypto.h>
  18 #include <linux/workqueue.h>
  19 #include <linux/backing-dev.h>
  20 #include <asm/atomic.h>
  21 #include <linux/scatterlist.h>
  22 #include <asm/page.h>
  23 #include <asm/unaligned.h>
  24
  25 #include "dm.h"
  26
  27 #define DM_MSG_PREFIX "crypt"
  28 #define MESG_STR(x) x, sizeof(x)
  29
  30 /*
  31  * per bio private data
  32  */
  33 struct crypt_io {
  34         struct dm_target *target;
  35         struct bio *base_bio;
  36         struct bio *first_clone;
  37         struct work_struct work;
  38         atomic_t pending;
  39         int error;
  40         int post_process;
  41 };
  42
  43 /*
  44  * context holding the current state of a multi-part conversion
  45  */
  46 struct convert_context {
  47         struct bio *bio_in;
  48         struct bio *bio_out;
  49         unsigned int offset_in;
  50         unsigned int offset_out;
  51         unsigned int idx_in;
  52         unsigned int idx_out;
  53         sector_t sector;
  54         int write;
  55 };
  56
  57 struct crypt_config;
  58
  59 struct crypt_iv_operations {
  60         int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
  61                    const char *opts);
  62         void (*dtr)(struct crypt_config *cc);
  63         const char *(*status)(struct crypt_config *cc);
  64         int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
  65 };
  66
  67 /*
  68  * Crypt: maps a linear range of a block device
  69  * and encrypts / decrypts at the same time.
  70  */
  71 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
  72 struct crypt_config {
  73         struct dm_dev *dev;
  74         sector_t start;
  75
  76         /*
  77          * pool for per bio private data and
  78          * for encryption buffer pages
  79          */
  80         mempool_t *io_pool;
  81         mempool_t *page_pool;
  82         struct bio_set *bs;
  83
  84         /*
  85          * crypto related data
  86          */
  87         struct crypt_iv_operations *iv_gen_ops;
  88         char *iv_mode;
  89         union {
  90                 struct crypto_cipher *essiv_tfm;
  91                 int benbi_shift;
  92         } iv_gen_private;
  93         sector_t iv_offset;
  94         unsigned int iv_size;
  95
  96         char cipher[CRYPTO_MAX_ALG_NAME];
  97         char chainmode[CRYPTO_MAX_ALG_NAME];
  98         struct crypto_blkcipher *tfm;
  99         unsigned long flags;
 100         unsigned int key_size;
 101         u8 key[0];
 102 };
 103
 104 #define MIN_IOS        16
 105 #define MIN_POOL_PAGES 32
 106 #define MIN_BIO_PAGES  8
 107
 108 static kmem_cache_t *_crypt_io_pool;
 109
 110 /*
 111  * Different IV generation algorithms:
 112  *
 113  * plain: the initial vector is the 32-bit little-endian version of the sector
 114  *        number, padded with zeros if neccessary.
 115  *
 116  * essiv: "encrypted sector|salt initial vector", the sector number is
 117  *        encrypted with the bulk cipher using a salt as key. The salt
 118  *        should be derived from the bulk cipher's key via hashing.
 119  *
 120  * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
 121  *        (needed for LRW-32-AES and possible other narrow block modes)
 122  *
 123  * plumb: unimplemented, see:
 124  * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 125  */
 126
 127 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 128 {
 129         memset(iv, 0, cc->iv_size);
 130         *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
 131
 132         return 0;
 133 }
 134
 135 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 136                               const char *opts)
 137 {
 138         struct crypto_cipher *essiv_tfm;
 139         struct crypto_hash *hash_tfm;
 140         struct hash_desc desc;
 141         struct scatterlist sg;
 142         unsigned int saltsize;
 143         u8 *salt;
 144         int err;
 145
 146         if (opts == NULL) {
 147                 ti->error = "Digest algorithm missing for ESSIV mode";
 148                 return -EINVAL;
 149         }
 150
 151         /* Hash the cipher key with the given hash algorithm */
 152         hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
 153         if (IS_ERR(hash_tfm)) {
 154                 ti->error = "Error initializing ESSIV hash";
 155                 return PTR_ERR(hash_tfm);
 156         }
 157
 158         saltsize = crypto_hash_digestsize(hash_tfm);
 159         salt = kmalloc(saltsize, GFP_KERNEL);
 160         if (salt == NULL) {
 161                 ti->error = "Error kmallocing salt storage in ESSIV";
 162                 crypto_free_hash(hash_tfm);
 163                 return -ENOMEM;
 164         }
 165
 166         sg_set_buf(&sg, cc->key, cc->key_size);
 167         desc.tfm = hash_tfm;
 168         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 169         err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
 170         crypto_free_hash(hash_tfm);
 171
 172         if (err) {
 173                 ti->error = "Error calculating hash in ESSIV";
 174                 return err;
 175         }
 176
 177         /* Setup the essiv_tfm with the given salt */
 178         essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 179         if (IS_ERR(essiv_tfm)) {
 180                 ti->error = "Error allocating crypto tfm for ESSIV";
 181                 kfree(salt);
 182                 return PTR_ERR(essiv_tfm);
 183         }
 184         if (crypto_cipher_blocksize(essiv_tfm) !=
 185             crypto_blkcipher_ivsize(cc->tfm)) {
 186                 ti->error = "Block size of ESSIV cipher does "
 187                                 "not match IV size of block cipher";
 188                 crypto_free_cipher(essiv_tfm);
 189                 kfree(salt);
 190                 return -EINVAL;
 191         }
 192         err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
 193         if (err) {
 194                 ti->error = "Failed to set key for ESSIV cipher";
 195                 crypto_free_cipher(essiv_tfm);
 196                 kfree(salt);
 197                 return err;
 198         }
 199         kfree(salt);
 200
 201         cc->iv_gen_private.essiv_tfm = essiv_tfm;
 202         return 0;
 203 }
 204
 205 static void crypt_iv_essiv_dtr(struct crypt_config *cc)
 206 {
 207         crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
 208         cc->iv_gen_private.essiv_tfm = NULL;
 209 }
 210
 211 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 212 {
 213         memset(iv, 0, cc->iv_size);
 214         *(u64 *)iv = cpu_to_le64(sector);
 215         crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
 216         return 0;
 217 }
 218
 219 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
 220                               const char *opts)
 221 {
 222         unsigned int bs = crypto_blkcipher_blocksize(cc->tfm);
 223         int log = long_log2(bs);
 224
 225         /* we need to calculate how far we must shift the sector count
 226          * to get the cipher block count, we use this shift in _gen */
 227
 228         if (1 << log != bs) {
 229                 ti->error = "cypher blocksize is not a power of 2";
 230                 return -EINVAL;
 231         }
 232
 233         if (log > 9) {
 234                 ti->error = "cypher blocksize is > 512";
 235                 return -EINVAL;
 236         }
 237
 238         cc->iv_gen_private.benbi_shift = 9 - log;
 239
 240         return 0;
 241 }
 242
 243 static void crypt_iv_benbi_dtr(struct crypt_config *cc)
 244 {
 245 }
 246
 247 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 248 {
 249         __be64 val;
 250
 251         memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
 252
 253         val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
 254         put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
 255
 256         return 0;
 257 }
 258
 259 static struct crypt_iv_operations crypt_iv_plain_ops = {
 260         .generator = crypt_iv_plain_gen
 261 };
 262
 263 static struct crypt_iv_operations crypt_iv_essiv_ops = {
 264         .ctr       = crypt_iv_essiv_ctr,
 265         .dtr       = crypt_iv_essiv_dtr,
 266         .generator = crypt_iv_essiv_gen
 267 };
 268
 269 static struct crypt_iv_operations crypt_iv_benbi_ops = {
 270         .ctr       = crypt_iv_benbi_ctr,
 271         .dtr       = crypt_iv_benbi_dtr,
 272         .generator = crypt_iv_benbi_gen
 273 };
 274
 275 static int
 276 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
 277                           struct scatterlist *in, unsigned int length,
 278                           int write, sector_t sector)
 279 {
 280         u8 iv[cc->iv_size] __attribute__ ((aligned(__alignof__(u64))));
 281         struct blkcipher_desc desc = {
 282                 .tfm = cc->tfm,
 283                 .info = iv,
 284                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP,
 285         };
 286         int r;
 287
 288         if (cc->iv_gen_ops) {
 289                 r = cc->iv_gen_ops->generator(cc, iv, sector);
 290                 if (r < 0)
 291                         return r;
 292
 293                 if (write)
 294                         r = crypto_blkcipher_encrypt_iv(&desc, out, in, length);
 295                 else
 296                         r = crypto_blkcipher_decrypt_iv(&desc, out, in, length);
 297         } else {
 298                 if (write)
 299                         r = crypto_blkcipher_encrypt(&desc, out, in, length);
 300                 else
 301                         r = crypto_blkcipher_decrypt(&desc, out, in, length);
 302         }
 303
 304         return r;
 305 }
 306
 307 static void
 308 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
 309                    struct bio *bio_out, struct bio *bio_in,
 310                    sector_t sector, int write)
 311 {
 312         ctx->bio_in = bio_in;
 313         ctx->bio_out = bio_out;
 314         ctx->offset_in = 0;
 315         ctx->offset_out = 0;
 316         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
 317         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
 318         ctx->sector = sector + cc->iv_offset;
 319         ctx->write = write;
 320 }
 321
 322 /*
 323  * Encrypt / decrypt data from one bio to another one (can be the same one)
 324  */
 325 static int crypt_convert(struct crypt_config *cc,
 326                          struct convert_context *ctx)
 327 {
 328         int r = 0;
 329
 330         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 331               ctx->idx_out < ctx->bio_out->bi_vcnt) {
 332                 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 333                 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 334                 struct scatterlist sg_in = {
 335                         .page = bv_in->bv_page,
 336                         .offset = bv_in->bv_offset + ctx->offset_in,
 337                         .length = 1 << SECTOR_SHIFT
 338                 };
 339                 struct scatterlist sg_out = {
 340                         .page = bv_out->bv_page,
 341                         .offset = bv_out->bv_offset + ctx->offset_out,
 342                         .length = 1 << SECTOR_SHIFT
 343                 };
 344
 345                 ctx->offset_in += sg_in.length;
 346                 if (ctx->offset_in >= bv_in->bv_len) {
 347                         ctx->offset_in = 0;
 348                         ctx->idx_in++;
 349                 }
 350
 351                 ctx->offset_out += sg_out.length;
 352                 if (ctx->offset_out >= bv_out->bv_len) {
 353                         ctx->offset_out = 0;
 354                         ctx->idx_out++;
 355                 }
 356
 357                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 358                                               ctx->write, ctx->sector);
 359                 if (r < 0)
 360                         break;
 361
 362                 ctx->sector++;
 363         }
 364
 365         return r;
 366 }
 367
 368  static void dm_crypt_bio_destructor(struct bio *bio)
 369  {
 370         struct crypt_io *io = bio->bi_private;
 371         struct crypt_config *cc = io->target->private;
 372
 373         bio_free(bio, cc->bs);
 374  }
 375
 376 /*
 377  * Generate a new unfragmented bio with the given size
 378  * This should never violate the device limitations
 379  * May return a smaller bio when running out of pages
 380  */
 381 static struct bio *
 382 crypt_alloc_buffer(struct crypt_config *cc, unsigned int size,
 383                    struct bio *base_bio, unsigned int *bio_vec_idx)
 384 {
 385         struct bio *clone;
 386         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 387         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 388         unsigned int i;
 389
 390         if (base_bio) {
 391                 clone = bio_alloc_bioset(GFP_NOIO, base_bio->bi_max_vecs, cc->bs);
 392                 __bio_clone(clone, base_bio);
 393         } else
 394                 clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
 395
 396         if (!clone)
 397                 return NULL;
 398
 399         clone->bi_destructor = dm_crypt_bio_destructor;
 400
 401         /* if the last bio was not complete, continue where that one ended */
 402         clone->bi_idx = *bio_vec_idx;
 403         clone->bi_vcnt = *bio_vec_idx;
 404         clone->bi_size = 0;
 405         clone->bi_flags &= ~(1 << BIO_SEG_VALID);
 406
 407         /* clone->bi_idx pages have already been allocated */
 408         size -= clone->bi_idx * PAGE_SIZE;
 409
 410         for (i = clone->bi_idx; i < nr_iovecs; i++) {
 411                 struct bio_vec *bv = bio_iovec_idx(clone, i);
 412
 413                 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
 414                 if (!bv->bv_page)
 415                         break;
 416
 417                 /*
 418                  * if additional pages cannot be allocated without waiting,
 419                  * return a partially allocated bio, the caller will then try
 420                  * to allocate additional bios while submitting this partial bio
 421                  */
 422                 if ((i - clone->bi_idx) == (MIN_BIO_PAGES - 1))
 423                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 424
 425                 bv->bv_offset = 0;
 426                 if (size > PAGE_SIZE)
 427                         bv->bv_len = PAGE_SIZE;
 428                 else
 429                         bv->bv_len = size;
 430
 431                 clone->bi_size += bv->bv_len;
 432                 clone->bi_vcnt++;
 433                 size -= bv->bv_len;
 434         }
 435
 436         if (!clone->bi_size) {
 437                 bio_put(clone);
 438                 return NULL;
 439         }
 440
 441         /*
 442          * Remember the last bio_vec allocated to be able
 443          * to correctly continue after the splitting.
 444          */
 445         *bio_vec_idx = clone->bi_vcnt;
 446
 447         return clone;
 448 }
 449
 450 static void crypt_free_buffer_pages(struct crypt_config *cc,
 451                                     struct bio *clone, unsigned int bytes)
 452 {
 453         unsigned int i, start, end;
 454         struct bio_vec *bv;
 455
 456         /*
 457          * This is ugly, but Jens Axboe thinks that using bi_idx in the
 458          * endio function is too dangerous at the moment, so I calculate the
 459          * correct position using bi_vcnt and bi_size.
 460          * The bv_offset and bv_len fields might already be modified but we
 461          * know that we always allocated whole pages.
 462          * A fix to the bi_idx issue in the kernel is in the works, so
 463          * we will hopefully be able to revert to the cleaner solution soon.
 464          */
 465         i = clone->bi_vcnt - 1;
 466         bv = bio_iovec_idx(clone, i);
 467         end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - clone->bi_size;
 468         start = end - bytes;
 469
 470         start >>= PAGE_SHIFT;
 471         if (!clone->bi_size)
 472                 end = clone->bi_vcnt;
 473         else
 474                 end >>= PAGE_SHIFT;
 475
 476         for (i = start; i < end; i++) {
 477                 bv = bio_iovec_idx(clone, i);
 478                 BUG_ON(!bv->bv_page);
 479                 mempool_free(bv->bv_page, cc->page_pool);
 480                 bv->bv_page = NULL;
 481         }
 482 }
 483
 484 /*
 485  * One of the bios was finished. Check for completion of
 486  * the whole request and correctly clean up the buffer.
 487  */
 488 static void dec_pending(struct crypt_io *io, int error)
 489 {
 490         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 491
 492         if (error < 0)
 493                 io->error = error;
 494
 495         if (!atomic_dec_and_test(&io->pending))
 496                 return;
 497
 498         if (io->first_clone)
 499                 bio_put(io->first_clone);
 500
 501         bio_endio(io->base_bio, io->base_bio->bi_size, io->error);
 502
 503         mempool_free(io, cc->io_pool);
 504 }
 505
 506 /*
 507  * kcryptd:
 508  *
 509  * Needed because it would be very unwise to do decryption in an
 510  * interrupt context.
 511  */
 512 static struct workqueue_struct *_kcryptd_workqueue;
 513 static void kcryptd_do_work(struct work_struct *work);
 514
 515 static void kcryptd_queue_io(struct crypt_io *io)
 516 {
 517         INIT_WORK(&io->work, kcryptd_do_work);
 518         queue_work(_kcryptd_workqueue, &io->work);
 519 }
 520
 521 static int crypt_endio(struct bio *clone, unsigned int done, int error)
 522 {
 523         struct crypt_io *io = clone->bi_private;
 524         struct crypt_config *cc = io->target->private;
 525         unsigned read_io = bio_data_dir(clone) == READ;
 526
 527         /*
 528          * free the processed pages, even if
 529          * it's only a partially completed write
 530          */
 531         if (!read_io)
 532                 crypt_free_buffer_pages(cc, clone, done);
 533
 534         /* keep going - not finished yet */
 535         if (unlikely(clone->bi_size))
 536                 return 1;
 537
 538         if (!read_io)
 539                 goto out;
 540
 541         if (unlikely(!bio_flagged(clone, BIO_UPTODATE))) {
 542                 error = -EIO;
 543                 goto out;
 544         }
 545
 546         bio_put(clone);
 547         io->post_process = 1;
 548         kcryptd_queue_io(io);
 549         return 0;
 550
 551 out:
 552         bio_put(clone);
 553         dec_pending(io, error);
 554         return error;
 555 }
 556
 557 static void clone_init(struct crypt_io *io, struct bio *clone)
 558 {
 559         struct crypt_config *cc = io->target->private;
 560
 561         clone->bi_private = io;
 562         clone->bi_end_io  = crypt_endio;
 563         clone->bi_bdev    = cc->dev->bdev;
 564         clone->bi_rw      = io->base_bio->bi_rw;
 565 }
 566
 567 static void process_read(struct crypt_io *io)
 568 {
 569         struct crypt_config *cc = io->target->private;
 570         struct bio *base_bio = io->base_bio;
 571         struct bio *clone;
 572         sector_t sector = base_bio->bi_sector - io->target->begin;
 573
 574         atomic_inc(&io->pending);
 575
 576         /*
 577          * The block layer might modify the bvec array, so always
 578          * copy the required bvecs because we need the original
 579          * one in order to decrypt the whole bio data *afterwards*.
 580          */
 581         clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
 582         if (unlikely(!clone)) {
 583                 dec_pending(io, -ENOMEM);
 584                 return;
 585         }
 586
 587         clone_init(io, clone);
 588         clone->bi_destructor = dm_crypt_bio_destructor;
 589         clone->bi_idx = 0;
 590         clone->bi_vcnt = bio_segments(base_bio);
 591         clone->bi_size = base_bio->bi_size;
 592         clone->bi_sector = cc->start + sector;
 593         memcpy(clone->bi_io_vec, bio_iovec(base_bio),
 594                sizeof(struct bio_vec) * clone->bi_vcnt);
 595
 596         generic_make_request(clone);
 597 }
 598
 599 static void process_write(struct crypt_io *io)
 600 {
 601         struct crypt_config *cc = io->target->private;
 602         struct bio *base_bio = io->base_bio;
 603         struct bio *clone;
 604         struct convert_context ctx;
 605         unsigned remaining = base_bio->bi_size;
 606         sector_t sector = base_bio->bi_sector - io->target->begin;
 607         unsigned bvec_idx = 0;
 608
 609         atomic_inc(&io->pending);
 610
 611         crypt_convert_init(cc, &ctx, NULL, base_bio, sector, 1);
 612
 613         /*
 614          * The allocated buffers can be smaller than the whole bio,
 615          * so repeat the whole process until all the data can be handled.
 616          */
 617         while (remaining) {
 618                 clone = crypt_alloc_buffer(cc, base_bio->bi_size,
 619                                            io->first_clone, &bvec_idx);
 620                 if (unlikely(!clone)) {
 621                         dec_pending(io, -ENOMEM);
 622                         return;
 623                 }
 624
 625                 ctx.bio_out = clone;
 626
 627                 if (unlikely(crypt_convert(cc, &ctx) < 0)) {
 628                         crypt_free_buffer_pages(cc, clone, clone->bi_size);
 629                         bio_put(clone);
 630                         dec_pending(io, -EIO);
 631                         return;
 632                 }
 633
 634                 clone_init(io, clone);
 635                 clone->bi_sector = cc->start + sector;
 636
 637                 if (!io->first_clone) {
 638                         /*
 639                          * hold a reference to the first clone, because it
 640                          * holds the bio_vec array and that can't be freed
 641                          * before all other clones are released
 642                          */
 643                         bio_get(clone);
 644                         io->first_clone = clone;
 645                 }
 646
 647                 remaining -= clone->bi_size;
 648                 sector += bio_sectors(clone);
 649
 650                 /* prevent bio_put of first_clone */
 651                 if (remaining)
 652                         atomic_inc(&io->pending);
 653
 654                 generic_make_request(clone);
 655
 656                 /* out of memory -> run queues */
 657                 if (remaining)
 658                         congestion_wait(bio_data_dir(clone), HZ/100);
 659         }
 660 }
 661
 662 static void process_read_endio(struct crypt_io *io)
 663 {
 664         struct crypt_config *cc = io->target->private;
 665         struct convert_context ctx;
 666
 667         crypt_convert_init(cc, &ctx, io->base_bio, io->base_bio,
 668                            io->base_bio->bi_sector - io->target->begin, 0);
 669
 670         dec_pending(io, crypt_convert(cc, &ctx));
 671 }
 672
 673 static void kcryptd_do_work(struct work_struct *work)
 674 {
 675         struct crypt_io *io = container_of(work, struct crypt_io, work);
 676
 677         if (io->post_process)
 678                 process_read_endio(io);
 679         else if (bio_data_dir(io->base_bio) == READ)
 680                 process_read(io);
 681         else
 682                 process_write(io);
 683 }
 684
 685 /*
 686  * Decode key from its hex representation
 687  */
 688 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 689 {
 690         char buffer[3];
 691         char *endp;
 692         unsigned int i;
 693
 694         buffer[2] = '\0';
 695
 696         for (i = 0; i < size; i++) {
 697                 buffer[0] = *hex++;
 698                 buffer[1] = *hex++;
 699
 700                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 701
 702                 if (endp != &buffer[2])
 703                         return -EINVAL;
 704         }
 705
 706         if (*hex != '\0')
 707                 return -EINVAL;
 708
 709         return 0;
 710 }
 711
 712 /*
 713  * Encode key into its hex representation
 714  */
 715 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
 716 {
 717         unsigned int i;
 718
 719         for (i = 0; i < size; i++) {
 720                 sprintf(hex, "%02x", *key);
 721                 hex += 2;
 722                 key++;
 723         }
 724 }
 725
 726 static int crypt_set_key(struct crypt_config *cc, char *key)
 727 {
 728         unsigned key_size = strlen(key) >> 1;
 729
 730         if (cc->key_size && cc->key_size != key_size)
 731                 return -EINVAL;
 732
 733         cc->key_size = key_size; /* initial settings */
 734
 735         if ((!key_size && strcmp(key, "-")) ||
 736             (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
 737                 return -EINVAL;
 738
 739         set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 740
 741         return 0;
 742 }
 743
 744 static int crypt_wipe_key(struct crypt_config *cc)
 745 {
 746         clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 747         memset(&cc->key, 0, cc->key_size * sizeof(u8));
 748         return 0;
 749 }
 750
 751 /*
 752  * Construct an encryption mapping:
 753  * <cipher> <key> <iv_offset> <dev_path> <start>
 754  */
 755 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 756 {
 757         struct crypt_config *cc;
 758         struct crypto_blkcipher *tfm;
 759         char *tmp;
 760         char *cipher;
 761         char *chainmode;
 762         char *ivmode;
 763         char *ivopts;
 764         unsigned int key_size;
 765         unsigned long long tmpll;
 766
 767         if (argc != 5) {
 768                 ti->error = "Not enough arguments";
 769                 return -EINVAL;
 770         }
 771
 772         tmp = argv[0];
 773         cipher = strsep(&tmp, "-");
 774         chainmode = strsep(&tmp, "-");
 775         ivopts = strsep(&tmp, "-");
 776         ivmode = strsep(&ivopts, ":");
 777
 778         if (tmp)
 779                 DMWARN("Unexpected additional cipher options");
 780
 781         key_size = strlen(argv[1]) >> 1;
 782
 783         cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 784         if (cc == NULL) {
 785                 ti->error =
 786                         "Cannot allocate transparent encryption context";
 787                 return -ENOMEM;
 788         }
 789
 790         if (crypt_set_key(cc, argv[1])) {
 791                 ti->error = "Error decoding key";
 792                 goto bad1;
 793         }
 794
 795         /* Compatiblity mode for old dm-crypt cipher strings */
 796         if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 797                 chainmode = "cbc";
 798                 ivmode = "plain";
 799         }
 800
 801         if (strcmp(chainmode, "ecb") && !ivmode) {
 802                 ti->error = "This chaining mode requires an IV mechanism";
 803                 goto bad1;
 804         }
 805
 806         if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", chainmode,
 807                      cipher) >= CRYPTO_MAX_ALG_NAME) {
 808                 ti->error = "Chain mode + cipher name is too long";
 809                 goto bad1;
 810         }
 811
 812         tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 813         if (IS_ERR(tfm)) {
 814                 ti->error = "Error allocating crypto tfm";
 815                 goto bad1;
 816         }
 817
 818         strcpy(cc->cipher, cipher);
 819         strcpy(cc->chainmode, chainmode);
 820         cc->tfm = tfm;
 821
 822         /*
 823          * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
 824          * See comments at iv code
 825          */
 826
 827         if (ivmode == NULL)
 828                 cc->iv_gen_ops = NULL;
 829         else if (strcmp(ivmode, "plain") == 0)
 830                 cc->iv_gen_ops = &crypt_iv_plain_ops;
 831         else if (strcmp(ivmode, "essiv") == 0)
 832                 cc->iv_gen_ops = &crypt_iv_essiv_ops;
 833         else if (strcmp(ivmode, "benbi") == 0)
 834                 cc->iv_gen_ops = &crypt_iv_benbi_ops;
 835         else {
 836                 ti->error = "Invalid IV mode";
 837                 goto bad2;
 838         }
 839
 840         if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
 841             cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
 842                 goto bad2;
 843
 844         cc->iv_size = crypto_blkcipher_ivsize(tfm);
 845         if (cc->iv_size)
 846                 /* at least a 64 bit sector number should fit in our buffer */
 847                 cc->iv_size = max(cc->iv_size,
 848                                   (unsigned int)(sizeof(u64) / sizeof(u8)));
 849         else {
 850                 if (cc->iv_gen_ops) {
 851                         DMWARN("Selected cipher does not support IVs");
 852                         if (cc->iv_gen_ops->dtr)
 853                                 cc->iv_gen_ops->dtr(cc);
 854                         cc->iv_gen_ops = NULL;
 855                 }
 856         }
 857
 858         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
 859         if (!cc->io_pool) {
 860                 ti->error = "Cannot allocate crypt io mempool";
 861                 goto bad3;
 862         }
 863
 864         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
 865         if (!cc->page_pool) {
 866                 ti->error = "Cannot allocate page mempool";
 867                 goto bad4;
 868         }
 869
 870         cc->bs = bioset_create(MIN_IOS, MIN_IOS, 4);
 871         if (!cc->bs) {
 872                 ti->error = "Cannot allocate crypt bioset";
 873                 goto bad_bs;
 874         }
 875
 876         if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
 877                 ti->error = "Error setting key";
 878                 goto bad5;
 879         }
 880
 881         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 882                 ti->error = "Invalid iv_offset sector";
 883                 goto bad5;
 884         }
 885         cc->iv_offset = tmpll;
 886
 887         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
 888                 ti->error = "Invalid device sector";
 889                 goto bad5;
 890         }
 891         cc->start = tmpll;
 892
 893         if (dm_get_device(ti, argv[3], cc->start, ti->len,
 894                           dm_table_get_mode(ti->table), &cc->dev)) {
 895                 ti->error = "Device lookup failed";
 896                 goto bad5;
 897         }
 898
 899         if (ivmode && cc->iv_gen_ops) {
 900                 if (ivopts)
 901                         *(ivopts - 1) = ':';
 902                 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
 903                 if (!cc->iv_mode) {
 904                         ti->error = "Error kmallocing iv_mode string";
 905                         goto bad5;
 906                 }
 907                 strcpy(cc->iv_mode, ivmode);
 908         } else
 909                 cc->iv_mode = NULL;
 910
 911         ti->private = cc;
 912         return 0;
 913
 914 bad5:
 915         bioset_free(cc->bs);
 916 bad_bs:
 917         mempool_destroy(cc->page_pool);
 918 bad4:
 919         mempool_destroy(cc->io_pool);
 920 bad3:
 921         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 922                 cc->iv_gen_ops->dtr(cc);
 923 bad2:
 924         crypto_free_blkcipher(tfm);
 925 bad1:
 926         /* Must zero key material before freeing */
 927         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 928         kfree(cc);
 929         return -EINVAL;
 930 }
 931
 932 static void crypt_dtr(struct dm_target *ti)
 933 {
 934         struct crypt_config *cc = (struct crypt_config *) ti->private;
 935
 936         bioset_free(cc->bs);
 937         mempool_destroy(cc->page_pool);
 938         mempool_destroy(cc->io_pool);
 939
 940         kfree(cc->iv_mode);
 941         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 942                 cc->iv_gen_ops->dtr(cc);
 943         crypto_free_blkcipher(cc->tfm);
 944         dm_put_device(ti, cc->dev);
 945
 946         /* Must zero key material before freeing */
 947         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 948         kfree(cc);
 949 }
 950
 951 static int crypt_map(struct dm_target *ti, struct bio *bio,
 952                      union map_info *map_context)
 953 {
 954         struct crypt_config *cc = ti->private;
 955         struct crypt_io *io;
 956
 957         io = mempool_alloc(cc->io_pool, GFP_NOIO);
 958         io->target = ti;
 959         io->base_bio = bio;
 960         io->first_clone = NULL;
 961         io->error = io->post_process = 0;
 962         atomic_set(&io->pending, 0);
 963         kcryptd_queue_io(io);
 964
 965         return 0;
 966 }
 967
 968 static int crypt_status(struct dm_target *ti, status_type_t type,
 969                         char *result, unsigned int maxlen)
 970 {
 971         struct crypt_config *cc = (struct crypt_config *) ti->private;
 972         unsigned int sz = 0;
 973
 974         switch (type) {
 975         case STATUSTYPE_INFO:
 976                 result[0] = '\0';
 977                 break;
 978
 979         case STATUSTYPE_TABLE:
 980                 if (cc->iv_mode)
 981                         DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
 982                                cc->iv_mode);
 983                 else
 984                         DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
 985
 986                 if (cc->key_size > 0) {
 987                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
 988                                 return -ENOMEM;
 989
 990                         crypt_encode_key(result + sz, cc->key, cc->key_size);
 991                         sz += cc->key_size << 1;
 992                 } else {
 993                         if (sz >= maxlen)
 994                                 return -ENOMEM;
 995                         result[sz++] = '-';
 996                 }
 997
 998                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
 999                                 cc->dev->name, (unsigned long long)cc->start);
1000                 break;
1001         }
1002         return 0;
1003 }
1004
1005 static void crypt_postsuspend(struct dm_target *ti)
1006 {
1007         struct crypt_config *cc = ti->private;
1008
1009         set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1010 }
1011
1012 static int crypt_preresume(struct dm_target *ti)
1013 {
1014         struct crypt_config *cc = ti->private;
1015
1016         if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
1017                 DMERR("aborting resume - crypt key is not set.");
1018                 return -EAGAIN;
1019         }
1020
1021         return 0;
1022 }
1023
1024 static void crypt_resume(struct dm_target *ti)
1025 {
1026         struct crypt_config *cc = ti->private;
1027
1028         clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1029 }
1030
1031 /* Message interface
1032  *      key set <key>
1033  *      key wipe
1034  */
1035 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1036 {
1037         struct crypt_config *cc = ti->private;
1038
1039         if (argc < 2)
1040                 goto error;
1041
1042         if (!strnicmp(argv[0], MESG_STR("key"))) {
1043                 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1044                         DMWARN("not suspended during key manipulation.");
1045                         return -EINVAL;
1046                 }
1047                 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1048                         return crypt_set_key(cc, argv[2]);
1049                 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1050                         return crypt_wipe_key(cc);
1051         }
1052
1053 error:
1054         DMWARN("unrecognised message received.");
1055         return -EINVAL;
1056 }
1057
1058 static struct target_type crypt_target = {
1059         .name   = "crypt",
1060         .version= {1, 3, 0},
1061         .module = THIS_MODULE,
1062         .ctr    = crypt_ctr,
1063         .dtr    = crypt_dtr,
1064         .map    = crypt_map,
1065         .status = crypt_status,
1066         .postsuspend = crypt_postsuspend,
1067         .preresume = crypt_preresume,
1068         .resume = crypt_resume,
1069         .message = crypt_message,
1070 };
1071
1072 static int __init dm_crypt_init(void)
1073 {
1074         int r;
1075
1076         _crypt_io_pool = kmem_cache_create("dm-crypt_io",
1077                                            sizeof(struct crypt_io),
1078                                            0, 0, NULL, NULL);
1079         if (!_crypt_io_pool)
1080                 return -ENOMEM;
1081
1082         _kcryptd_workqueue = create_workqueue("kcryptd");
1083         if (!_kcryptd_workqueue) {
1084                 r = -ENOMEM;
1085                 DMERR("couldn't create kcryptd");
1086                 goto bad1;
1087         }
1088
1089         r = dm_register_target(&crypt_target);
1090         if (r < 0) {
1091                 DMERR("register failed %d", r);
1092                 goto bad2;
1093         }
1094
1095         return 0;
1096
1097 bad2:
1098         destroy_workqueue(_kcryptd_workqueue);
1099 bad1:
1100         kmem_cache_destroy(_crypt_io_pool);
1101         return r;
1102 }
1103
1104 static void __exit dm_crypt_exit(void)
1105 {
1106         int r = dm_unregister_target(&crypt_target);
1107
1108         if (r < 0)
1109                 DMERR("unregister failed %d", r);
1110
1111         destroy_workqueue(_kcryptd_workqueue);
1112         kmem_cache_destroy(_crypt_io_pool);
1113 }
1114
1115 module_init(dm_crypt_init);
1116 module_exit(dm_crypt_exit);
1117
1118 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1119 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1120 MODULE_LICENSE("GPL");