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 work_struct work;
  37         atomic_t pending;
  38         int error;
  39         int post_process;
  40 };
  41
  42 /*
  43  * context holding the current state of a multi-part conversion
  44  */
  45 struct convert_context {
  46         struct bio *bio_in;
  47         struct bio *bio_out;
  48         unsigned int offset_in;
  49         unsigned int offset_out;
  50         unsigned int idx_in;
  51         unsigned int idx_out;
  52         sector_t sector;
  53         int write;
  54 };
  55
  56 struct crypt_config;
  57
  58 struct crypt_iv_operations {
  59         int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
  60                    const char *opts);
  61         void (*dtr)(struct crypt_config *cc);
  62         const char *(*status)(struct crypt_config *cc);
  63         int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
  64 };
  65
  66 /*
  67  * Crypt: maps a linear range of a block device
  68  * and encrypts / decrypts at the same time.
  69  */
  70 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
  71 struct crypt_config {
  72         struct dm_dev *dev;
  73         sector_t start;
  74
  75         /*
  76          * pool for per bio private data and
  77          * for encryption buffer pages
  78          */
  79         mempool_t *io_pool;
  80         mempool_t *page_pool;
  81         struct bio_set *bs;
  82
  83         /*
  84          * crypto related data
  85          */
  86         struct crypt_iv_operations *iv_gen_ops;
  87         char *iv_mode;
  88         union {
  89                 struct crypto_cipher *essiv_tfm;
  90                 int benbi_shift;
  91         } iv_gen_private;
  92         sector_t iv_offset;
  93         unsigned int iv_size;
  94
  95         char cipher[CRYPTO_MAX_ALG_NAME];
  96         char chainmode[CRYPTO_MAX_ALG_NAME];
  97         struct crypto_blkcipher *tfm;
  98         unsigned long flags;
  99         unsigned int key_size;
 100         u8 key[0];
 101 };
 102
 103 #define MIN_IOS        16
 104 #define MIN_POOL_PAGES 32
 105 #define MIN_BIO_PAGES  8
 106
 107 static struct kmem_cache *_crypt_io_pool;
 108
 109 static void clone_init(struct crypt_io *, struct bio *);
 110
 111 /*
 112  * Different IV generation algorithms:
 113  *
 114  * plain: the initial vector is the 32-bit little-endian version of the sector
 115  *        number, padded with zeros if neccessary.
 116  *
 117  * essiv: "encrypted sector|salt initial vector", the sector number is
 118  *        encrypted with the bulk cipher using a salt as key. The salt
 119  *        should be derived from the bulk cipher's key via hashing.
 120  *
 121  * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
 122  *        (needed for LRW-32-AES and possible other narrow block modes)
 123  *
 124  * plumb: unimplemented, see:
 125  * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 126  */
 127
 128 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 129 {
 130         memset(iv, 0, cc->iv_size);
 131         *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
 132
 133         return 0;
 134 }
 135
 136 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 137                               const char *opts)
 138 {
 139         struct crypto_cipher *essiv_tfm;
 140         struct crypto_hash *hash_tfm;
 141         struct hash_desc desc;
 142         struct scatterlist sg;
 143         unsigned int saltsize;
 144         u8 *salt;
 145         int err;
 146
 147         if (opts == NULL) {
 148                 ti->error = "Digest algorithm missing for ESSIV mode";
 149                 return -EINVAL;
 150         }
 151
 152         /* Hash the cipher key with the given hash algorithm */
 153         hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
 154         if (IS_ERR(hash_tfm)) {
 155                 ti->error = "Error initializing ESSIV hash";
 156                 return PTR_ERR(hash_tfm);
 157         }
 158
 159         saltsize = crypto_hash_digestsize(hash_tfm);
 160         salt = kmalloc(saltsize, GFP_KERNEL);
 161         if (salt == NULL) {
 162                 ti->error = "Error kmallocing salt storage in ESSIV";
 163                 crypto_free_hash(hash_tfm);
 164                 return -ENOMEM;
 165         }
 166
 167         sg_set_buf(&sg, cc->key, cc->key_size);
 168         desc.tfm = hash_tfm;
 169         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 170         err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
 171         crypto_free_hash(hash_tfm);
 172
 173         if (err) {
 174                 ti->error = "Error calculating hash in ESSIV";
 175                 return err;
 176         }
 177
 178         /* Setup the essiv_tfm with the given salt */
 179         essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 180         if (IS_ERR(essiv_tfm)) {
 181                 ti->error = "Error allocating crypto tfm for ESSIV";
 182                 kfree(salt);
 183                 return PTR_ERR(essiv_tfm);
 184         }
 185         if (crypto_cipher_blocksize(essiv_tfm) !=
 186             crypto_blkcipher_ivsize(cc->tfm)) {
 187                 ti->error = "Block size of ESSIV cipher does "
 188                                 "not match IV size of block cipher";
 189                 crypto_free_cipher(essiv_tfm);
 190                 kfree(salt);
 191                 return -EINVAL;
 192         }
 193         err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
 194         if (err) {
 195                 ti->error = "Failed to set key for ESSIV cipher";
 196                 crypto_free_cipher(essiv_tfm);
 197                 kfree(salt);
 198                 return err;
 199         }
 200         kfree(salt);
 201
 202         cc->iv_gen_private.essiv_tfm = essiv_tfm;
 203         return 0;
 204 }
 205
 206 static void crypt_iv_essiv_dtr(struct crypt_config *cc)
 207 {
 208         crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
 209         cc->iv_gen_private.essiv_tfm = NULL;
 210 }
 211
 212 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 213 {
 214         memset(iv, 0, cc->iv_size);
 215         *(u64 *)iv = cpu_to_le64(sector);
 216         crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
 217         return 0;
 218 }
 219
 220 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
 221                               const char *opts)
 222 {
 223         unsigned int bs = crypto_blkcipher_blocksize(cc->tfm);
 224         int log = ilog2(bs);
 225
 226         /* we need to calculate how far we must shift the sector count
 227          * to get the cipher block count, we use this shift in _gen */
 228
 229         if (1 << log != bs) {
 230                 ti->error = "cypher blocksize is not a power of 2";
 231                 return -EINVAL;
 232         }
 233
 234         if (log > 9) {
 235                 ti->error = "cypher blocksize is > 512";
 236                 return -EINVAL;
 237         }
 238
 239         cc->iv_gen_private.benbi_shift = 9 - log;
 240
 241         return 0;
 242 }
 243
 244 static void crypt_iv_benbi_dtr(struct crypt_config *cc)
 245 {
 246 }
 247
 248 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 249 {
 250         __be64 val;
 251
 252         memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
 253
 254         val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
 255         put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
 256
 257         return 0;
 258 }
 259
 260 static struct crypt_iv_operations crypt_iv_plain_ops = {
 261         .generator = crypt_iv_plain_gen
 262 };
 263
 264 static struct crypt_iv_operations crypt_iv_essiv_ops = {
 265         .ctr       = crypt_iv_essiv_ctr,
 266         .dtr       = crypt_iv_essiv_dtr,
 267         .generator = crypt_iv_essiv_gen
 268 };
 269
 270 static struct crypt_iv_operations crypt_iv_benbi_ops = {
 271         .ctr       = crypt_iv_benbi_ctr,
 272         .dtr       = crypt_iv_benbi_dtr,
 273         .generator = crypt_iv_benbi_gen
 274 };
 275
 276 static int
 277 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
 278                           struct scatterlist *in, unsigned int length,
 279                           int write, sector_t sector)
 280 {
 281         u8 iv[cc->iv_size] __attribute__ ((aligned(__alignof__(u64))));
 282         struct blkcipher_desc desc = {
 283                 .tfm = cc->tfm,
 284                 .info = iv,
 285                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP,
 286         };
 287         int r;
 288
 289         if (cc->iv_gen_ops) {
 290                 r = cc->iv_gen_ops->generator(cc, iv, sector);
 291                 if (r < 0)
 292                         return r;
 293
 294                 if (write)
 295                         r = crypto_blkcipher_encrypt_iv(&desc, out, in, length);
 296                 else
 297                         r = crypto_blkcipher_decrypt_iv(&desc, out, in, length);
 298         } else {
 299                 if (write)
 300                         r = crypto_blkcipher_encrypt(&desc, out, in, length);
 301                 else
 302                         r = crypto_blkcipher_decrypt(&desc, out, in, length);
 303         }
 304
 305         return r;
 306 }
 307
 308 static void
 309 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
 310                    struct bio *bio_out, struct bio *bio_in,
 311                    sector_t sector, int write)
 312 {
 313         ctx->bio_in = bio_in;
 314         ctx->bio_out = bio_out;
 315         ctx->offset_in = 0;
 316         ctx->offset_out = 0;
 317         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
 318         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
 319         ctx->sector = sector + cc->iv_offset;
 320         ctx->write = write;
 321 }
 322
 323 /*
 324  * Encrypt / decrypt data from one bio to another one (can be the same one)
 325  */
 326 static int crypt_convert(struct crypt_config *cc,
 327                          struct convert_context *ctx)
 328 {
 329         int r = 0;
 330
 331         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 332               ctx->idx_out < ctx->bio_out->bi_vcnt) {
 333                 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 334                 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 335                 struct scatterlist sg_in = {
 336                         .page = bv_in->bv_page,
 337                         .offset = bv_in->bv_offset + ctx->offset_in,
 338                         .length = 1 << SECTOR_SHIFT
 339                 };
 340                 struct scatterlist sg_out = {
 341                         .page = bv_out->bv_page,
 342                         .offset = bv_out->bv_offset + ctx->offset_out,
 343                         .length = 1 << SECTOR_SHIFT
 344                 };
 345
 346                 ctx->offset_in += sg_in.length;
 347                 if (ctx->offset_in >= bv_in->bv_len) {
 348                         ctx->offset_in = 0;
 349                         ctx->idx_in++;
 350                 }
 351
 352                 ctx->offset_out += sg_out.length;
 353                 if (ctx->offset_out >= bv_out->bv_len) {
 354                         ctx->offset_out = 0;
 355                         ctx->idx_out++;
 356                 }
 357
 358                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 359                                               ctx->write, ctx->sector);
 360                 if (r < 0)
 361                         break;
 362
 363                 ctx->sector++;
 364         }
 365
 366         return r;
 367 }
 368
 369  static void dm_crypt_bio_destructor(struct bio *bio)
 370  {
 371         struct crypt_io *io = bio->bi_private;
 372         struct crypt_config *cc = io->target->private;
 373
 374         bio_free(bio, cc->bs);
 375  }
 376
 377 /*
 378  * Generate a new unfragmented bio with the given size
 379  * This should never violate the device limitations
 380  * May return a smaller bio when running out of pages
 381  */
 382 static struct bio *crypt_alloc_buffer(struct crypt_io *io, unsigned int size,
 383                                       unsigned int *bio_vec_idx)
 384 {
 385         struct crypt_config *cc = io->target->private;
 386         struct bio *clone;
 387         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 388         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 389         unsigned int i;
 390
 391         clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
 392         if (!clone)
 393                 return NULL;
 394
 395         clone_init(io, clone);
 396
 397         /* if the last bio was not complete, continue where that one ended */
 398         clone->bi_idx = *bio_vec_idx;
 399         clone->bi_vcnt = *bio_vec_idx;
 400         clone->bi_size = 0;
 401         clone->bi_flags &= ~(1 << BIO_SEG_VALID);
 402
 403         /* clone->bi_idx pages have already been allocated */
 404         size -= clone->bi_idx * PAGE_SIZE;
 405
 406         for (i = clone->bi_idx; i < nr_iovecs; i++) {
 407                 struct bio_vec *bv = bio_iovec_idx(clone, i);
 408
 409                 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
 410                 if (!bv->bv_page)
 411                         break;
 412
 413                 /*
 414                  * if additional pages cannot be allocated without waiting,
 415                  * return a partially allocated bio, the caller will then try
 416                  * to allocate additional bios while submitting this partial bio
 417                  */
 418                 if ((i - clone->bi_idx) == (MIN_BIO_PAGES - 1))
 419                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 420
 421                 bv->bv_offset = 0;
 422                 if (size > PAGE_SIZE)
 423                         bv->bv_len = PAGE_SIZE;
 424                 else
 425                         bv->bv_len = size;
 426
 427                 clone->bi_size += bv->bv_len;
 428                 clone->bi_vcnt++;
 429                 size -= bv->bv_len;
 430         }
 431
 432         if (!clone->bi_size) {
 433                 bio_put(clone);
 434                 return NULL;
 435         }
 436
 437         /*
 438          * Remember the last bio_vec allocated to be able
 439          * to correctly continue after the splitting.
 440          */
 441         *bio_vec_idx = clone->bi_vcnt;
 442
 443         return clone;
 444 }
 445
 446 static void crypt_free_buffer_pages(struct crypt_config *cc,
 447                                     struct bio *clone, unsigned int bytes)
 448 {
 449         unsigned int i, start, end;
 450         struct bio_vec *bv;
 451
 452         /*
 453          * This is ugly, but Jens Axboe thinks that using bi_idx in the
 454          * endio function is too dangerous at the moment, so I calculate the
 455          * correct position using bi_vcnt and bi_size.
 456          * The bv_offset and bv_len fields might already be modified but we
 457          * know that we always allocated whole pages.
 458          * A fix to the bi_idx issue in the kernel is in the works, so
 459          * we will hopefully be able to revert to the cleaner solution soon.
 460          */
 461         i = clone->bi_vcnt - 1;
 462         bv = bio_iovec_idx(clone, i);
 463         end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - clone->bi_size;
 464         start = end - bytes;
 465
 466         start >>= PAGE_SHIFT;
 467         if (!clone->bi_size)
 468                 end = clone->bi_vcnt;
 469         else
 470                 end >>= PAGE_SHIFT;
 471
 472         for (i = start; i < end; i++) {
 473                 bv = bio_iovec_idx(clone, i);
 474                 BUG_ON(!bv->bv_page);
 475                 mempool_free(bv->bv_page, cc->page_pool);
 476                 bv->bv_page = NULL;
 477         }
 478 }
 479
 480 /*
 481  * One of the bios was finished. Check for completion of
 482  * the whole request and correctly clean up the buffer.
 483  */
 484 static void dec_pending(struct crypt_io *io, int error)
 485 {
 486         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 487
 488         if (error < 0)
 489                 io->error = error;
 490
 491         if (!atomic_dec_and_test(&io->pending))
 492                 return;
 493
 494         bio_endio(io->base_bio, io->base_bio->bi_size, io->error);
 495
 496         mempool_free(io, cc->io_pool);
 497 }
 498
 499 /*
 500  * kcryptd:
 501  *
 502  * Needed because it would be very unwise to do decryption in an
 503  * interrupt context.
 504  */
 505 static struct workqueue_struct *_kcryptd_workqueue;
 506 static void kcryptd_do_work(struct work_struct *work);
 507
 508 static void kcryptd_queue_io(struct crypt_io *io)
 509 {
 510         INIT_WORK(&io->work, kcryptd_do_work);
 511         queue_work(_kcryptd_workqueue, &io->work);
 512 }
 513
 514 static int crypt_endio(struct bio *clone, unsigned int done, int error)
 515 {
 516         struct crypt_io *io = clone->bi_private;
 517         struct crypt_config *cc = io->target->private;
 518         unsigned read_io = bio_data_dir(clone) == READ;
 519
 520         /*
 521          * free the processed pages, even if
 522          * it's only a partially completed write
 523          */
 524         if (!read_io)
 525                 crypt_free_buffer_pages(cc, clone, done);
 526
 527         /* keep going - not finished yet */
 528         if (unlikely(clone->bi_size))
 529                 return 1;
 530
 531         if (!read_io)
 532                 goto out;
 533
 534         if (unlikely(!bio_flagged(clone, BIO_UPTODATE))) {
 535                 error = -EIO;
 536                 goto out;
 537         }
 538
 539         bio_put(clone);
 540         io->post_process = 1;
 541         kcryptd_queue_io(io);
 542         return 0;
 543
 544 out:
 545         bio_put(clone);
 546         dec_pending(io, error);
 547         return error;
 548 }
 549
 550 static void clone_init(struct crypt_io *io, struct bio *clone)
 551 {
 552         struct crypt_config *cc = io->target->private;
 553
 554         clone->bi_private = io;
 555         clone->bi_end_io  = crypt_endio;
 556         clone->bi_bdev    = cc->dev->bdev;
 557         clone->bi_rw      = io->base_bio->bi_rw;
 558         clone->bi_destructor = dm_crypt_bio_destructor;
 559 }
 560
 561 static void process_read(struct crypt_io *io)
 562 {
 563         struct crypt_config *cc = io->target->private;
 564         struct bio *base_bio = io->base_bio;
 565         struct bio *clone;
 566         sector_t sector = base_bio->bi_sector - io->target->begin;
 567
 568         atomic_inc(&io->pending);
 569
 570         /*
 571          * The block layer might modify the bvec array, so always
 572          * copy the required bvecs because we need the original
 573          * one in order to decrypt the whole bio data *afterwards*.
 574          */
 575         clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
 576         if (unlikely(!clone)) {
 577                 dec_pending(io, -ENOMEM);
 578                 return;
 579         }
 580
 581         clone_init(io, clone);
 582         clone->bi_idx = 0;
 583         clone->bi_vcnt = bio_segments(base_bio);
 584         clone->bi_size = base_bio->bi_size;
 585         clone->bi_sector = cc->start + sector;
 586         memcpy(clone->bi_io_vec, bio_iovec(base_bio),
 587                sizeof(struct bio_vec) * clone->bi_vcnt);
 588
 589         generic_make_request(clone);
 590 }
 591
 592 static void process_write(struct crypt_io *io)
 593 {
 594         struct crypt_config *cc = io->target->private;
 595         struct bio *base_bio = io->base_bio;
 596         struct bio *clone;
 597         struct convert_context ctx;
 598         unsigned remaining = base_bio->bi_size;
 599         sector_t sector = base_bio->bi_sector - io->target->begin;
 600         unsigned bvec_idx = 0;
 601
 602         atomic_inc(&io->pending);
 603
 604         crypt_convert_init(cc, &ctx, NULL, base_bio, sector, 1);
 605
 606         /*
 607          * The allocated buffers can be smaller than the whole bio,
 608          * so repeat the whole process until all the data can be handled.
 609          */
 610         while (remaining) {
 611                 clone = crypt_alloc_buffer(io, base_bio->bi_size, &bvec_idx);
 612                 if (unlikely(!clone)) {
 613                         dec_pending(io, -ENOMEM);
 614                         return;
 615                 }
 616
 617                 ctx.bio_out = clone;
 618
 619                 if (unlikely(crypt_convert(cc, &ctx) < 0)) {
 620                         crypt_free_buffer_pages(cc, clone, clone->bi_size);
 621                         bio_put(clone);
 622                         dec_pending(io, -EIO);
 623                         return;
 624                 }
 625
 626                 clone->bi_sector = cc->start + sector;
 627                 remaining -= clone->bi_size;
 628                 sector += bio_sectors(clone);
 629
 630                 /* Grab another reference to the io struct
 631                  * before we kick off the request */
 632                 if (remaining)
 633                         atomic_inc(&io->pending);
 634
 635                 generic_make_request(clone);
 636
 637                 /* Do not reference clone after this - it
 638                  * may be gone already. */
 639
 640                 /* out of memory -> run queues */
 641                 if (remaining)
 642                         congestion_wait(WRITE, HZ/100);
 643         }
 644 }
 645
 646 static void process_read_endio(struct crypt_io *io)
 647 {
 648         struct crypt_config *cc = io->target->private;
 649         struct convert_context ctx;
 650
 651         crypt_convert_init(cc, &ctx, io->base_bio, io->base_bio,
 652                            io->base_bio->bi_sector - io->target->begin, 0);
 653
 654         dec_pending(io, crypt_convert(cc, &ctx));
 655 }
 656
 657 static void kcryptd_do_work(struct work_struct *work)
 658 {
 659         struct crypt_io *io = container_of(work, struct crypt_io, work);
 660
 661         if (io->post_process)
 662                 process_read_endio(io);
 663         else if (bio_data_dir(io->base_bio) == READ)
 664                 process_read(io);
 665         else
 666                 process_write(io);
 667 }
 668
 669 /*
 670  * Decode key from its hex representation
 671  */
 672 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 673 {
 674         char buffer[3];
 675         char *endp;
 676         unsigned int i;
 677
 678         buffer[2] = '\0';
 679
 680         for (i = 0; i < size; i++) {
 681                 buffer[0] = *hex++;
 682                 buffer[1] = *hex++;
 683
 684                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 685
 686                 if (endp != &buffer[2])
 687                         return -EINVAL;
 688         }
 689
 690         if (*hex != '\0')
 691                 return -EINVAL;
 692
 693         return 0;
 694 }
 695
 696 /*
 697  * Encode key into its hex representation
 698  */
 699 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
 700 {
 701         unsigned int i;
 702
 703         for (i = 0; i < size; i++) {
 704                 sprintf(hex, "%02x", *key);
 705                 hex += 2;
 706                 key++;
 707         }
 708 }
 709
 710 static int crypt_set_key(struct crypt_config *cc, char *key)
 711 {
 712         unsigned key_size = strlen(key) >> 1;
 713
 714         if (cc->key_size && cc->key_size != key_size)
 715                 return -EINVAL;
 716
 717         cc->key_size = key_size; /* initial settings */
 718
 719         if ((!key_size && strcmp(key, "-")) ||
 720             (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
 721                 return -EINVAL;
 722
 723         set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 724
 725         return 0;
 726 }
 727
 728 static int crypt_wipe_key(struct crypt_config *cc)
 729 {
 730         clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 731         memset(&cc->key, 0, cc->key_size * sizeof(u8));
 732         return 0;
 733 }
 734
 735 /*
 736  * Construct an encryption mapping:
 737  * <cipher> <key> <iv_offset> <dev_path> <start>
 738  */
 739 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 740 {
 741         struct crypt_config *cc;
 742         struct crypto_blkcipher *tfm;
 743         char *tmp;
 744         char *cipher;
 745         char *chainmode;
 746         char *ivmode;
 747         char *ivopts;
 748         unsigned int key_size;
 749         unsigned long long tmpll;
 750
 751         if (argc != 5) {
 752                 ti->error = "Not enough arguments";
 753                 return -EINVAL;
 754         }
 755
 756         tmp = argv[0];
 757         cipher = strsep(&tmp, "-");
 758         chainmode = strsep(&tmp, "-");
 759         ivopts = strsep(&tmp, "-");
 760         ivmode = strsep(&ivopts, ":");
 761
 762         if (tmp)
 763                 DMWARN("Unexpected additional cipher options");
 764
 765         key_size = strlen(argv[1]) >> 1;
 766
 767         cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 768         if (cc == NULL) {
 769                 ti->error =
 770                         "Cannot allocate transparent encryption context";
 771                 return -ENOMEM;
 772         }
 773
 774         if (crypt_set_key(cc, argv[1])) {
 775                 ti->error = "Error decoding key";
 776                 goto bad1;
 777         }
 778
 779         /* Compatiblity mode for old dm-crypt cipher strings */
 780         if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 781                 chainmode = "cbc";
 782                 ivmode = "plain";
 783         }
 784
 785         if (strcmp(chainmode, "ecb") && !ivmode) {
 786                 ti->error = "This chaining mode requires an IV mechanism";
 787                 goto bad1;
 788         }
 789
 790         if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", chainmode,
 791                      cipher) >= CRYPTO_MAX_ALG_NAME) {
 792                 ti->error = "Chain mode + cipher name is too long";
 793                 goto bad1;
 794         }
 795
 796         tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 797         if (IS_ERR(tfm)) {
 798                 ti->error = "Error allocating crypto tfm";
 799                 goto bad1;
 800         }
 801
 802         strcpy(cc->cipher, cipher);
 803         strcpy(cc->chainmode, chainmode);
 804         cc->tfm = tfm;
 805
 806         /*
 807          * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
 808          * See comments at iv code
 809          */
 810
 811         if (ivmode == NULL)
 812                 cc->iv_gen_ops = NULL;
 813         else if (strcmp(ivmode, "plain") == 0)
 814                 cc->iv_gen_ops = &crypt_iv_plain_ops;
 815         else if (strcmp(ivmode, "essiv") == 0)
 816                 cc->iv_gen_ops = &crypt_iv_essiv_ops;
 817         else if (strcmp(ivmode, "benbi") == 0)
 818                 cc->iv_gen_ops = &crypt_iv_benbi_ops;
 819         else {
 820                 ti->error = "Invalid IV mode";
 821                 goto bad2;
 822         }
 823
 824         if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
 825             cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
 826                 goto bad2;
 827
 828         cc->iv_size = crypto_blkcipher_ivsize(tfm);
 829         if (cc->iv_size)
 830                 /* at least a 64 bit sector number should fit in our buffer */
 831                 cc->iv_size = max(cc->iv_size,
 832                                   (unsigned int)(sizeof(u64) / sizeof(u8)));
 833         else {
 834                 if (cc->iv_gen_ops) {
 835                         DMWARN("Selected cipher does not support IVs");
 836                         if (cc->iv_gen_ops->dtr)
 837                                 cc->iv_gen_ops->dtr(cc);
 838                         cc->iv_gen_ops = NULL;
 839                 }
 840         }
 841
 842         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
 843         if (!cc->io_pool) {
 844                 ti->error = "Cannot allocate crypt io mempool";
 845                 goto bad3;
 846         }
 847
 848         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
 849         if (!cc->page_pool) {
 850                 ti->error = "Cannot allocate page mempool";
 851                 goto bad4;
 852         }
 853
 854         cc->bs = bioset_create(MIN_IOS, MIN_IOS, 4);
 855         if (!cc->bs) {
 856                 ti->error = "Cannot allocate crypt bioset";
 857                 goto bad_bs;
 858         }
 859
 860         if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
 861                 ti->error = "Error setting key";
 862                 goto bad5;
 863         }
 864
 865         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 866                 ti->error = "Invalid iv_offset sector";
 867                 goto bad5;
 868         }
 869         cc->iv_offset = tmpll;
 870
 871         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
 872                 ti->error = "Invalid device sector";
 873                 goto bad5;
 874         }
 875         cc->start = tmpll;
 876
 877         if (dm_get_device(ti, argv[3], cc->start, ti->len,
 878                           dm_table_get_mode(ti->table), &cc->dev)) {
 879                 ti->error = "Device lookup failed";
 880                 goto bad5;
 881         }
 882
 883         if (ivmode && cc->iv_gen_ops) {
 884                 if (ivopts)
 885                         *(ivopts - 1) = ':';
 886                 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
 887                 if (!cc->iv_mode) {
 888                         ti->error = "Error kmallocing iv_mode string";
 889                         goto bad5;
 890                 }
 891                 strcpy(cc->iv_mode, ivmode);
 892         } else
 893                 cc->iv_mode = NULL;
 894
 895         ti->private = cc;
 896         return 0;
 897
 898 bad5:
 899         bioset_free(cc->bs);
 900 bad_bs:
 901         mempool_destroy(cc->page_pool);
 902 bad4:
 903         mempool_destroy(cc->io_pool);
 904 bad3:
 905         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 906                 cc->iv_gen_ops->dtr(cc);
 907 bad2:
 908         crypto_free_blkcipher(tfm);
 909 bad1:
 910         /* Must zero key material before freeing */
 911         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 912         kfree(cc);
 913         return -EINVAL;
 914 }
 915
 916 static void crypt_dtr(struct dm_target *ti)
 917 {
 918         struct crypt_config *cc = (struct crypt_config *) ti->private;
 919
 920         flush_workqueue(_kcryptd_workqueue);
 921
 922         bioset_free(cc->bs);
 923         mempool_destroy(cc->page_pool);
 924         mempool_destroy(cc->io_pool);
 925
 926         kfree(cc->iv_mode);
 927         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 928                 cc->iv_gen_ops->dtr(cc);
 929         crypto_free_blkcipher(cc->tfm);
 930         dm_put_device(ti, cc->dev);
 931
 932         /* Must zero key material before freeing */
 933         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 934         kfree(cc);
 935 }
 936
 937 static int crypt_map(struct dm_target *ti, struct bio *bio,
 938                      union map_info *map_context)
 939 {
 940         struct crypt_config *cc = ti->private;
 941         struct crypt_io *io;
 942
 943         io = mempool_alloc(cc->io_pool, GFP_NOIO);
 944         io->target = ti;
 945         io->base_bio = bio;
 946         io->error = io->post_process = 0;
 947         atomic_set(&io->pending, 0);
 948         kcryptd_queue_io(io);
 949
 950         return DM_MAPIO_SUBMITTED;
 951 }
 952
 953 static int crypt_status(struct dm_target *ti, status_type_t type,
 954                         char *result, unsigned int maxlen)
 955 {
 956         struct crypt_config *cc = (struct crypt_config *) ti->private;
 957         unsigned int sz = 0;
 958
 959         switch (type) {
 960         case STATUSTYPE_INFO:
 961                 result[0] = '\0';
 962                 break;
 963
 964         case STATUSTYPE_TABLE:
 965                 if (cc->iv_mode)
 966                         DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
 967                                cc->iv_mode);
 968                 else
 969                         DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
 970
 971                 if (cc->key_size > 0) {
 972                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
 973                                 return -ENOMEM;
 974
 975                         crypt_encode_key(result + sz, cc->key, cc->key_size);
 976                         sz += cc->key_size << 1;
 977                 } else {
 978                         if (sz >= maxlen)
 979                                 return -ENOMEM;
 980                         result[sz++] = '-';
 981                 }
 982
 983                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
 984                                 cc->dev->name, (unsigned long long)cc->start);
 985                 break;
 986         }
 987         return 0;
 988 }
 989
 990 static void crypt_postsuspend(struct dm_target *ti)
 991 {
 992         struct crypt_config *cc = ti->private;
 993
 994         set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
 995 }
 996
 997 static int crypt_preresume(struct dm_target *ti)
 998 {
 999         struct crypt_config *cc = ti->private;
1000
1001         if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
1002                 DMERR("aborting resume - crypt key is not set.");
1003                 return -EAGAIN;
1004         }
1005
1006         return 0;
1007 }
1008
1009 static void crypt_resume(struct dm_target *ti)
1010 {
1011         struct crypt_config *cc = ti->private;
1012
1013         clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1014 }
1015
1016 /* Message interface
1017  *      key set <key>
1018  *      key wipe
1019  */
1020 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1021 {
1022         struct crypt_config *cc = ti->private;
1023
1024         if (argc < 2)
1025                 goto error;
1026
1027         if (!strnicmp(argv[0], MESG_STR("key"))) {
1028                 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1029                         DMWARN("not suspended during key manipulation.");
1030                         return -EINVAL;
1031                 }
1032                 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1033                         return crypt_set_key(cc, argv[2]);
1034                 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1035                         return crypt_wipe_key(cc);
1036         }
1037
1038 error:
1039         DMWARN("unrecognised message received.");
1040         return -EINVAL;
1041 }
1042
1043 static struct target_type crypt_target = {
1044         .name   = "crypt",
1045         .version= {1, 3, 0},
1046         .module = THIS_MODULE,
1047         .ctr    = crypt_ctr,
1048         .dtr    = crypt_dtr,
1049         .map    = crypt_map,
1050         .status = crypt_status,
1051         .postsuspend = crypt_postsuspend,
1052         .preresume = crypt_preresume,
1053         .resume = crypt_resume,
1054         .message = crypt_message,
1055 };
1056
1057 static int __init dm_crypt_init(void)
1058 {
1059         int r;
1060
1061         _crypt_io_pool = kmem_cache_create("dm-crypt_io",
1062                                            sizeof(struct crypt_io),
1063                                            0, 0, NULL, NULL);
1064         if (!_crypt_io_pool)
1065                 return -ENOMEM;
1066
1067         _kcryptd_workqueue = create_workqueue("kcryptd");
1068         if (!_kcryptd_workqueue) {
1069                 r = -ENOMEM;
1070                 DMERR("couldn't create kcryptd");
1071                 goto bad1;
1072         }
1073
1074         r = dm_register_target(&crypt_target);
1075         if (r < 0) {
1076                 DMERR("register failed %d", r);
1077                 goto bad2;
1078         }
1079
1080         return 0;
1081
1082 bad2:
1083         destroy_workqueue(_kcryptd_workqueue);
1084 bad1:
1085         kmem_cache_destroy(_crypt_io_pool);
1086         return r;
1087 }
1088
1089 static void __exit dm_crypt_exit(void)
1090 {
1091         int r = dm_unregister_target(&crypt_target);
1092
1093         if (r < 0)
1094                 DMERR("unregister failed %d", r);
1095
1096         destroy_workqueue(_kcryptd_workqueue);
1097         kmem_cache_destroy(_crypt_io_pool);
1098 }
1099
1100 module_init(dm_crypt_init);
1101 module_exit(dm_crypt_exit);
1102
1103 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1104 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1105 MODULE_LICENSE("GPL");