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 dm_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         struct workqueue_struct *queue;
  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 struct kmem_cache *_crypt_io_pool;
 109
 110 static void clone_init(struct dm_crypt_io *, struct bio *);
 111
 112 /*
 113  * Different IV generation algorithms:
 114  *
 115  * plain: the initial vector is the 32-bit little-endian version of the sector
 116  *        number, padded with zeros if neccessary.
 117  *
 118  * essiv: "encrypted sector|salt initial vector", the sector number is
 119  *        encrypted with the bulk cipher using a salt as key. The salt
 120  *        should be derived from the bulk cipher's key via hashing.
 121  *
 122  * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
 123  *        (needed for LRW-32-AES and possible other narrow block modes)
 124  *
 125  * null: the initial vector is always zero.  Provides compatibility with
 126  *       obsolete loop_fish2 devices.  Do not use for new devices.
 127  *
 128  * plumb: unimplemented, see:
 129  * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 130  */
 131
 132 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 133 {
 134         memset(iv, 0, cc->iv_size);
 135         *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
 136
 137         return 0;
 138 }
 139
 140 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 141                               const char *opts)
 142 {
 143         struct crypto_cipher *essiv_tfm;
 144         struct crypto_hash *hash_tfm;
 145         struct hash_desc desc;
 146         struct scatterlist sg;
 147         unsigned int saltsize;
 148         u8 *salt;
 149         int err;
 150
 151         if (opts == NULL) {
 152                 ti->error = "Digest algorithm missing for ESSIV mode";
 153                 return -EINVAL;
 154         }
 155
 156         /* Hash the cipher key with the given hash algorithm */
 157         hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
 158         if (IS_ERR(hash_tfm)) {
 159                 ti->error = "Error initializing ESSIV hash";
 160                 return PTR_ERR(hash_tfm);
 161         }
 162
 163         saltsize = crypto_hash_digestsize(hash_tfm);
 164         salt = kmalloc(saltsize, GFP_KERNEL);
 165         if (salt == NULL) {
 166                 ti->error = "Error kmallocing salt storage in ESSIV";
 167                 crypto_free_hash(hash_tfm);
 168                 return -ENOMEM;
 169         }
 170
 171         sg_set_buf(&sg, cc->key, cc->key_size);
 172         desc.tfm = hash_tfm;
 173         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 174         err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
 175         crypto_free_hash(hash_tfm);
 176
 177         if (err) {
 178                 ti->error = "Error calculating hash in ESSIV";
 179                 kfree(salt);
 180                 return err;
 181         }
 182
 183         /* Setup the essiv_tfm with the given salt */
 184         essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 185         if (IS_ERR(essiv_tfm)) {
 186                 ti->error = "Error allocating crypto tfm for ESSIV";
 187                 kfree(salt);
 188                 return PTR_ERR(essiv_tfm);
 189         }
 190         if (crypto_cipher_blocksize(essiv_tfm) !=
 191             crypto_blkcipher_ivsize(cc->tfm)) {
 192                 ti->error = "Block size of ESSIV cipher does "
 193                                 "not match IV size of block cipher";
 194                 crypto_free_cipher(essiv_tfm);
 195                 kfree(salt);
 196                 return -EINVAL;
 197         }
 198         err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
 199         if (err) {
 200                 ti->error = "Failed to set key for ESSIV cipher";
 201                 crypto_free_cipher(essiv_tfm);
 202                 kfree(salt);
 203                 return err;
 204         }
 205         kfree(salt);
 206
 207         cc->iv_gen_private.essiv_tfm = essiv_tfm;
 208         return 0;
 209 }
 210
 211 static void crypt_iv_essiv_dtr(struct crypt_config *cc)
 212 {
 213         crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
 214         cc->iv_gen_private.essiv_tfm = NULL;
 215 }
 216
 217 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 218 {
 219         memset(iv, 0, cc->iv_size);
 220         *(u64 *)iv = cpu_to_le64(sector);
 221         crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
 222         return 0;
 223 }
 224
 225 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
 226                               const char *opts)
 227 {
 228         unsigned int bs = crypto_blkcipher_blocksize(cc->tfm);
 229         int log = ilog2(bs);
 230
 231         /* we need to calculate how far we must shift the sector count
 232          * to get the cipher block count, we use this shift in _gen */
 233
 234         if (1 << log != bs) {
 235                 ti->error = "cypher blocksize is not a power of 2";
 236                 return -EINVAL;
 237         }
 238
 239         if (log > 9) {
 240                 ti->error = "cypher blocksize is > 512";
 241                 return -EINVAL;
 242         }
 243
 244         cc->iv_gen_private.benbi_shift = 9 - log;
 245
 246         return 0;
 247 }
 248
 249 static void crypt_iv_benbi_dtr(struct crypt_config *cc)
 250 {
 251 }
 252
 253 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 254 {
 255         __be64 val;
 256
 257         memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
 258
 259         val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
 260         put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
 261
 262         return 0;
 263 }
 264
 265 static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 266 {
 267         memset(iv, 0, cc->iv_size);
 268
 269         return 0;
 270 }
 271
 272 static struct crypt_iv_operations crypt_iv_plain_ops = {
 273         .generator = crypt_iv_plain_gen
 274 };
 275
 276 static struct crypt_iv_operations crypt_iv_essiv_ops = {
 277         .ctr       = crypt_iv_essiv_ctr,
 278         .dtr       = crypt_iv_essiv_dtr,
 279         .generator = crypt_iv_essiv_gen
 280 };
 281
 282 static struct crypt_iv_operations crypt_iv_benbi_ops = {
 283         .ctr       = crypt_iv_benbi_ctr,
 284         .dtr       = crypt_iv_benbi_dtr,
 285         .generator = crypt_iv_benbi_gen
 286 };
 287
 288 static struct crypt_iv_operations crypt_iv_null_ops = {
 289         .generator = crypt_iv_null_gen
 290 };
 291
 292 static int
 293 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
 294                           struct scatterlist *in, unsigned int length,
 295                           int write, sector_t sector)
 296 {
 297         u8 iv[cc->iv_size] __attribute__ ((aligned(__alignof__(u64))));
 298         struct blkcipher_desc desc = {
 299                 .tfm = cc->tfm,
 300                 .info = iv,
 301                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP,
 302         };
 303         int r;
 304
 305         if (cc->iv_gen_ops) {
 306                 r = cc->iv_gen_ops->generator(cc, iv, sector);
 307                 if (r < 0)
 308                         return r;
 309
 310                 if (write)
 311                         r = crypto_blkcipher_encrypt_iv(&desc, out, in, length);
 312                 else
 313                         r = crypto_blkcipher_decrypt_iv(&desc, out, in, length);
 314         } else {
 315                 if (write)
 316                         r = crypto_blkcipher_encrypt(&desc, out, in, length);
 317                 else
 318                         r = crypto_blkcipher_decrypt(&desc, out, in, length);
 319         }
 320
 321         return r;
 322 }
 323
 324 static void
 325 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
 326                    struct bio *bio_out, struct bio *bio_in,
 327                    sector_t sector, int write)
 328 {
 329         ctx->bio_in = bio_in;
 330         ctx->bio_out = bio_out;
 331         ctx->offset_in = 0;
 332         ctx->offset_out = 0;
 333         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
 334         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
 335         ctx->sector = sector + cc->iv_offset;
 336         ctx->write = write;
 337 }
 338
 339 /*
 340  * Encrypt / decrypt data from one bio to another one (can be the same one)
 341  */
 342 static int crypt_convert(struct crypt_config *cc,
 343                          struct convert_context *ctx)
 344 {
 345         int r = 0;
 346
 347         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 348               ctx->idx_out < ctx->bio_out->bi_vcnt) {
 349                 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 350                 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 351                 struct scatterlist sg_in = {
 352                         .page = bv_in->bv_page,
 353                         .offset = bv_in->bv_offset + ctx->offset_in,
 354                         .length = 1 << SECTOR_SHIFT
 355                 };
 356                 struct scatterlist sg_out = {
 357                         .page = bv_out->bv_page,
 358                         .offset = bv_out->bv_offset + ctx->offset_out,
 359                         .length = 1 << SECTOR_SHIFT
 360                 };
 361
 362                 ctx->offset_in += sg_in.length;
 363                 if (ctx->offset_in >= bv_in->bv_len) {
 364                         ctx->offset_in = 0;
 365                         ctx->idx_in++;
 366                 }
 367
 368                 ctx->offset_out += sg_out.length;
 369                 if (ctx->offset_out >= bv_out->bv_len) {
 370                         ctx->offset_out = 0;
 371                         ctx->idx_out++;
 372                 }
 373
 374                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 375                                               ctx->write, ctx->sector);
 376                 if (r < 0)
 377                         break;
 378
 379                 ctx->sector++;
 380         }
 381
 382         return r;
 383 }
 384
 385  static void dm_crypt_bio_destructor(struct bio *bio)
 386  {
 387         struct dm_crypt_io *io = bio->bi_private;
 388         struct crypt_config *cc = io->target->private;
 389
 390         bio_free(bio, cc->bs);
 391  }
 392
 393 /*
 394  * Generate a new unfragmented bio with the given size
 395  * This should never violate the device limitations
 396  * May return a smaller bio when running out of pages
 397  */
 398 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
 399 {
 400         struct crypt_config *cc = io->target->private;
 401         struct bio *clone;
 402         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 403         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 404         unsigned int i;
 405
 406         clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
 407         if (!clone)
 408                 return NULL;
 409
 410         clone_init(io, clone);
 411
 412         for (i = 0; i < nr_iovecs; i++) {
 413                 struct bio_vec *bv = bio_iovec_idx(clone, i);
 414
 415                 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
 416                 if (!bv->bv_page)
 417                         break;
 418
 419                 /*
 420                  * if additional pages cannot be allocated without waiting,
 421                  * return a partially allocated bio, the caller will then try
 422                  * to allocate additional bios while submitting this partial bio
 423                  */
 424                 if (i == (MIN_BIO_PAGES - 1))
 425                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 426
 427                 bv->bv_offset = 0;
 428                 if (size > PAGE_SIZE)
 429                         bv->bv_len = PAGE_SIZE;
 430                 else
 431                         bv->bv_len = size;
 432
 433                 clone->bi_size += bv->bv_len;
 434                 clone->bi_vcnt++;
 435                 size -= bv->bv_len;
 436         }
 437
 438         if (!clone->bi_size) {
 439                 bio_put(clone);
 440                 return NULL;
 441         }
 442
 443         return clone;
 444 }
 445
 446 static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
 447 {
 448         unsigned int i;
 449         struct bio_vec *bv;
 450
 451         for (i = 0; i < clone->bi_vcnt; i++) {
 452                 bv = bio_iovec_idx(clone, i);
 453                 BUG_ON(!bv->bv_page);
 454                 mempool_free(bv->bv_page, cc->page_pool);
 455                 bv->bv_page = NULL;
 456         }
 457 }
 458
 459 /*
 460  * One of the bios was finished. Check for completion of
 461  * the whole request and correctly clean up the buffer.
 462  */
 463 static void dec_pending(struct dm_crypt_io *io, int error)
 464 {
 465         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 466
 467         if (error < 0)
 468                 io->error = error;
 469
 470         if (!atomic_dec_and_test(&io->pending))
 471                 return;
 472
 473         bio_endio(io->base_bio, io->error);
 474
 475         mempool_free(io, cc->io_pool);
 476 }
 477
 478 /*
 479  * kcryptd:
 480  *
 481  * Needed because it would be very unwise to do decryption in an
 482  * interrupt context.
 483  */
 484 static void kcryptd_do_work(struct work_struct *work);
 485
 486 static void kcryptd_queue_io(struct dm_crypt_io *io)
 487 {
 488         struct crypt_config *cc = io->target->private;
 489
 490         INIT_WORK(&io->work, kcryptd_do_work);
 491         queue_work(cc->queue, &io->work);
 492 }
 493
 494 static void crypt_endio(struct bio *clone, int error)
 495 {
 496         struct dm_crypt_io *io = clone->bi_private;
 497         struct crypt_config *cc = io->target->private;
 498         unsigned read_io = bio_data_dir(clone) == READ;
 499
 500         /*
 501          * free the processed pages
 502          */
 503         if (!read_io) {
 504                 crypt_free_buffer_pages(cc, clone);
 505                 goto out;
 506         }
 507
 508         if (unlikely(!bio_flagged(clone, BIO_UPTODATE))) {
 509                 error = -EIO;
 510                 goto out;
 511         }
 512
 513         bio_put(clone);
 514         io->post_process = 1;
 515         kcryptd_queue_io(io);
 516         return;
 517
 518 out:
 519         bio_put(clone);
 520         dec_pending(io, error);
 521 }
 522
 523 static void clone_init(struct dm_crypt_io *io, struct bio *clone)
 524 {
 525         struct crypt_config *cc = io->target->private;
 526
 527         clone->bi_private = io;
 528         clone->bi_end_io  = crypt_endio;
 529         clone->bi_bdev    = cc->dev->bdev;
 530         clone->bi_rw      = io->base_bio->bi_rw;
 531         clone->bi_destructor = dm_crypt_bio_destructor;
 532 }
 533
 534 static void process_read(struct dm_crypt_io *io)
 535 {
 536         struct crypt_config *cc = io->target->private;
 537         struct bio *base_bio = io->base_bio;
 538         struct bio *clone;
 539         sector_t sector = base_bio->bi_sector - io->target->begin;
 540
 541         atomic_inc(&io->pending);
 542
 543         /*
 544          * The block layer might modify the bvec array, so always
 545          * copy the required bvecs because we need the original
 546          * one in order to decrypt the whole bio data *afterwards*.
 547          */
 548         clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
 549         if (unlikely(!clone)) {
 550                 dec_pending(io, -ENOMEM);
 551                 return;
 552         }
 553
 554         clone_init(io, clone);
 555         clone->bi_idx = 0;
 556         clone->bi_vcnt = bio_segments(base_bio);
 557         clone->bi_size = base_bio->bi_size;
 558         clone->bi_sector = cc->start + sector;
 559         memcpy(clone->bi_io_vec, bio_iovec(base_bio),
 560                sizeof(struct bio_vec) * clone->bi_vcnt);
 561
 562         generic_make_request(clone);
 563 }
 564
 565 static void process_write(struct dm_crypt_io *io)
 566 {
 567         struct crypt_config *cc = io->target->private;
 568         struct bio *base_bio = io->base_bio;
 569         struct bio *clone;
 570         struct convert_context ctx;
 571         unsigned remaining = base_bio->bi_size;
 572         sector_t sector = base_bio->bi_sector - io->target->begin;
 573
 574         atomic_inc(&io->pending);
 575
 576         crypt_convert_init(cc, &ctx, NULL, base_bio, sector, 1);
 577
 578         /*
 579          * The allocated buffers can be smaller than the whole bio,
 580          * so repeat the whole process until all the data can be handled.
 581          */
 582         while (remaining) {
 583                 clone = crypt_alloc_buffer(io, remaining);
 584                 if (unlikely(!clone)) {
 585                         dec_pending(io, -ENOMEM);
 586                         return;
 587                 }
 588
 589                 ctx.bio_out = clone;
 590                 ctx.idx_out = 0;
 591
 592                 if (unlikely(crypt_convert(cc, &ctx) < 0)) {
 593                         crypt_free_buffer_pages(cc, clone);
 594                         bio_put(clone);
 595                         dec_pending(io, -EIO);
 596                         return;
 597                 }
 598
 599                 /* crypt_convert should have filled the clone bio */
 600                 BUG_ON(ctx.idx_out < clone->bi_vcnt);
 601
 602                 clone->bi_sector = cc->start + sector;
 603                 remaining -= clone->bi_size;
 604                 sector += bio_sectors(clone);
 605
 606                 /* Grab another reference to the io struct
 607                  * before we kick off the request */
 608                 if (remaining)
 609                         atomic_inc(&io->pending);
 610
 611                 generic_make_request(clone);
 612
 613                 /* Do not reference clone after this - it
 614                  * may be gone already. */
 615
 616                 /* out of memory -> run queues */
 617                 if (remaining)
 618                         congestion_wait(WRITE, HZ/100);
 619         }
 620 }
 621
 622 static void process_read_endio(struct dm_crypt_io *io)
 623 {
 624         struct crypt_config *cc = io->target->private;
 625         struct convert_context ctx;
 626
 627         crypt_convert_init(cc, &ctx, io->base_bio, io->base_bio,
 628                            io->base_bio->bi_sector - io->target->begin, 0);
 629
 630         dec_pending(io, crypt_convert(cc, &ctx));
 631 }
 632
 633 static void kcryptd_do_work(struct work_struct *work)
 634 {
 635         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 636
 637         if (io->post_process)
 638                 process_read_endio(io);
 639         else if (bio_data_dir(io->base_bio) == READ)
 640                 process_read(io);
 641         else
 642                 process_write(io);
 643 }
 644
 645 /*
 646  * Decode key from its hex representation
 647  */
 648 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 649 {
 650         char buffer[3];
 651         char *endp;
 652         unsigned int i;
 653
 654         buffer[2] = '\0';
 655
 656         for (i = 0; i < size; i++) {
 657                 buffer[0] = *hex++;
 658                 buffer[1] = *hex++;
 659
 660                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 661
 662                 if (endp != &buffer[2])
 663                         return -EINVAL;
 664         }
 665
 666         if (*hex != '\0')
 667                 return -EINVAL;
 668
 669         return 0;
 670 }
 671
 672 /*
 673  * Encode key into its hex representation
 674  */
 675 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
 676 {
 677         unsigned int i;
 678
 679         for (i = 0; i < size; i++) {
 680                 sprintf(hex, "%02x", *key);
 681                 hex += 2;
 682                 key++;
 683         }
 684 }
 685
 686 static int crypt_set_key(struct crypt_config *cc, char *key)
 687 {
 688         unsigned key_size = strlen(key) >> 1;
 689
 690         if (cc->key_size && cc->key_size != key_size)
 691                 return -EINVAL;
 692
 693         cc->key_size = key_size; /* initial settings */
 694
 695         if ((!key_size && strcmp(key, "-")) ||
 696             (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
 697                 return -EINVAL;
 698
 699         set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 700
 701         return 0;
 702 }
 703
 704 static int crypt_wipe_key(struct crypt_config *cc)
 705 {
 706         clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 707         memset(&cc->key, 0, cc->key_size * sizeof(u8));
 708         return 0;
 709 }
 710
 711 /*
 712  * Construct an encryption mapping:
 713  * <cipher> <key> <iv_offset> <dev_path> <start>
 714  */
 715 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 716 {
 717         struct crypt_config *cc;
 718         struct crypto_blkcipher *tfm;
 719         char *tmp;
 720         char *cipher;
 721         char *chainmode;
 722         char *ivmode;
 723         char *ivopts;
 724         unsigned int key_size;
 725         unsigned long long tmpll;
 726
 727         if (argc != 5) {
 728                 ti->error = "Not enough arguments";
 729                 return -EINVAL;
 730         }
 731
 732         tmp = argv[0];
 733         cipher = strsep(&tmp, "-");
 734         chainmode = strsep(&tmp, "-");
 735         ivopts = strsep(&tmp, "-");
 736         ivmode = strsep(&ivopts, ":");
 737
 738         if (tmp)
 739                 DMWARN("Unexpected additional cipher options");
 740
 741         key_size = strlen(argv[1]) >> 1;
 742
 743         cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 744         if (cc == NULL) {
 745                 ti->error =
 746                         "Cannot allocate transparent encryption context";
 747                 return -ENOMEM;
 748         }
 749
 750         if (crypt_set_key(cc, argv[1])) {
 751                 ti->error = "Error decoding key";
 752                 goto bad1;
 753         }
 754
 755         /* Compatiblity mode for old dm-crypt cipher strings */
 756         if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 757                 chainmode = "cbc";
 758                 ivmode = "plain";
 759         }
 760
 761         if (strcmp(chainmode, "ecb") && !ivmode) {
 762                 ti->error = "This chaining mode requires an IV mechanism";
 763                 goto bad1;
 764         }
 765
 766         if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", chainmode,
 767                      cipher) >= CRYPTO_MAX_ALG_NAME) {
 768                 ti->error = "Chain mode + cipher name is too long";
 769                 goto bad1;
 770         }
 771
 772         tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 773         if (IS_ERR(tfm)) {
 774                 ti->error = "Error allocating crypto tfm";
 775                 goto bad1;
 776         }
 777
 778         strcpy(cc->cipher, cipher);
 779         strcpy(cc->chainmode, chainmode);
 780         cc->tfm = tfm;
 781
 782         /*
 783          * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
 784          * See comments at iv code
 785          */
 786
 787         if (ivmode == NULL)
 788                 cc->iv_gen_ops = NULL;
 789         else if (strcmp(ivmode, "plain") == 0)
 790                 cc->iv_gen_ops = &crypt_iv_plain_ops;
 791         else if (strcmp(ivmode, "essiv") == 0)
 792                 cc->iv_gen_ops = &crypt_iv_essiv_ops;
 793         else if (strcmp(ivmode, "benbi") == 0)
 794                 cc->iv_gen_ops = &crypt_iv_benbi_ops;
 795         else if (strcmp(ivmode, "null") == 0)
 796                 cc->iv_gen_ops = &crypt_iv_null_ops;
 797         else {
 798                 ti->error = "Invalid IV mode";
 799                 goto bad2;
 800         }
 801
 802         if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
 803             cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
 804                 goto bad2;
 805
 806         cc->iv_size = crypto_blkcipher_ivsize(tfm);
 807         if (cc->iv_size)
 808                 /* at least a 64 bit sector number should fit in our buffer */
 809                 cc->iv_size = max(cc->iv_size,
 810                                   (unsigned int)(sizeof(u64) / sizeof(u8)));
 811         else {
 812                 if (cc->iv_gen_ops) {
 813                         DMWARN("Selected cipher does not support IVs");
 814                         if (cc->iv_gen_ops->dtr)
 815                                 cc->iv_gen_ops->dtr(cc);
 816                         cc->iv_gen_ops = NULL;
 817                 }
 818         }
 819
 820         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
 821         if (!cc->io_pool) {
 822                 ti->error = "Cannot allocate crypt io mempool";
 823                 goto bad3;
 824         }
 825
 826         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
 827         if (!cc->page_pool) {
 828                 ti->error = "Cannot allocate page mempool";
 829                 goto bad4;
 830         }
 831
 832         cc->bs = bioset_create(MIN_IOS, MIN_IOS);
 833         if (!cc->bs) {
 834                 ti->error = "Cannot allocate crypt bioset";
 835                 goto bad_bs;
 836         }
 837
 838         if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
 839                 ti->error = "Error setting key";
 840                 goto bad5;
 841         }
 842
 843         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 844                 ti->error = "Invalid iv_offset sector";
 845                 goto bad5;
 846         }
 847         cc->iv_offset = tmpll;
 848
 849         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
 850                 ti->error = "Invalid device sector";
 851                 goto bad5;
 852         }
 853         cc->start = tmpll;
 854
 855         if (dm_get_device(ti, argv[3], cc->start, ti->len,
 856                           dm_table_get_mode(ti->table), &cc->dev)) {
 857                 ti->error = "Device lookup failed";
 858                 goto bad5;
 859         }
 860
 861         if (ivmode && cc->iv_gen_ops) {
 862                 if (ivopts)
 863                         *(ivopts - 1) = ':';
 864                 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
 865                 if (!cc->iv_mode) {
 866                         ti->error = "Error kmallocing iv_mode string";
 867                         goto bad_iv_mode;
 868                 }
 869                 strcpy(cc->iv_mode, ivmode);
 870         } else
 871                 cc->iv_mode = NULL;
 872
 873         cc->queue = create_singlethread_workqueue("kcryptd");
 874         if (!cc->queue) {
 875                 ti->error = "Couldn't create kcryptd queue";
 876                 goto bad_queue;
 877         }
 878
 879         ti->private = cc;
 880         return 0;
 881
 882 bad_queue:
 883         kfree(cc->iv_mode);
 884 bad_iv_mode:
 885         dm_put_device(ti, cc->dev);
 886 bad5:
 887         bioset_free(cc->bs);
 888 bad_bs:
 889         mempool_destroy(cc->page_pool);
 890 bad4:
 891         mempool_destroy(cc->io_pool);
 892 bad3:
 893         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 894                 cc->iv_gen_ops->dtr(cc);
 895 bad2:
 896         crypto_free_blkcipher(tfm);
 897 bad1:
 898         /* Must zero key material before freeing */
 899         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 900         kfree(cc);
 901         return -EINVAL;
 902 }
 903
 904 static void crypt_dtr(struct dm_target *ti)
 905 {
 906         struct crypt_config *cc = (struct crypt_config *) ti->private;
 907
 908         destroy_workqueue(cc->queue);
 909
 910         bioset_free(cc->bs);
 911         mempool_destroy(cc->page_pool);
 912         mempool_destroy(cc->io_pool);
 913
 914         kfree(cc->iv_mode);
 915         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 916                 cc->iv_gen_ops->dtr(cc);
 917         crypto_free_blkcipher(cc->tfm);
 918         dm_put_device(ti, cc->dev);
 919
 920         /* Must zero key material before freeing */
 921         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 922         kfree(cc);
 923 }
 924
 925 static int crypt_map(struct dm_target *ti, struct bio *bio,
 926                      union map_info *map_context)
 927 {
 928         struct crypt_config *cc = ti->private;
 929         struct dm_crypt_io *io;
 930
 931         io = mempool_alloc(cc->io_pool, GFP_NOIO);
 932         io->target = ti;
 933         io->base_bio = bio;
 934         io->error = io->post_process = 0;
 935         atomic_set(&io->pending, 0);
 936         kcryptd_queue_io(io);
 937
 938         return DM_MAPIO_SUBMITTED;
 939 }
 940
 941 static int crypt_status(struct dm_target *ti, status_type_t type,
 942                         char *result, unsigned int maxlen)
 943 {
 944         struct crypt_config *cc = (struct crypt_config *) ti->private;
 945         unsigned int sz = 0;
 946
 947         switch (type) {
 948         case STATUSTYPE_INFO:
 949                 result[0] = '\0';
 950                 break;
 951
 952         case STATUSTYPE_TABLE:
 953                 if (cc->iv_mode)
 954                         DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
 955                                cc->iv_mode);
 956                 else
 957                         DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
 958
 959                 if (cc->key_size > 0) {
 960                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
 961                                 return -ENOMEM;
 962
 963                         crypt_encode_key(result + sz, cc->key, cc->key_size);
 964                         sz += cc->key_size << 1;
 965                 } else {
 966                         if (sz >= maxlen)
 967                                 return -ENOMEM;
 968                         result[sz++] = '-';
 969                 }
 970
 971                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
 972                                 cc->dev->name, (unsigned long long)cc->start);
 973                 break;
 974         }
 975         return 0;
 976 }
 977
 978 static void crypt_postsuspend(struct dm_target *ti)
 979 {
 980         struct crypt_config *cc = ti->private;
 981
 982         set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
 983 }
 984
 985 static int crypt_preresume(struct dm_target *ti)
 986 {
 987         struct crypt_config *cc = ti->private;
 988
 989         if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
 990                 DMERR("aborting resume - crypt key is not set.");
 991                 return -EAGAIN;
 992         }
 993
 994         return 0;
 995 }
 996
 997 static void crypt_resume(struct dm_target *ti)
 998 {
 999         struct crypt_config *cc = ti->private;
1000
1001         clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1002 }
1003
1004 /* Message interface
1005  *      key set <key>
1006  *      key wipe
1007  */
1008 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1009 {
1010         struct crypt_config *cc = ti->private;
1011
1012         if (argc < 2)
1013                 goto error;
1014
1015         if (!strnicmp(argv[0], MESG_STR("key"))) {
1016                 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1017                         DMWARN("not suspended during key manipulation.");
1018                         return -EINVAL;
1019                 }
1020                 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1021                         return crypt_set_key(cc, argv[2]);
1022                 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1023                         return crypt_wipe_key(cc);
1024         }
1025
1026 error:
1027         DMWARN("unrecognised message received.");
1028         return -EINVAL;
1029 }
1030
1031 static struct target_type crypt_target = {
1032         .name   = "crypt",
1033         .version= {1, 5, 0},
1034         .module = THIS_MODULE,
1035         .ctr    = crypt_ctr,
1036         .dtr    = crypt_dtr,
1037         .map    = crypt_map,
1038         .status = crypt_status,
1039         .postsuspend = crypt_postsuspend,
1040         .preresume = crypt_preresume,
1041         .resume = crypt_resume,
1042         .message = crypt_message,
1043 };
1044
1045 static int __init dm_crypt_init(void)
1046 {
1047         int r;
1048
1049         _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
1050         if (!_crypt_io_pool)
1051                 return -ENOMEM;
1052
1053         r = dm_register_target(&crypt_target);
1054         if (r < 0) {
1055                 DMERR("register failed %d", r);
1056                 kmem_cache_destroy(_crypt_io_pool);
1057         }
1058
1059         return r;
1060 }
1061
1062 static void __exit dm_crypt_exit(void)
1063 {
1064         int r = dm_unregister_target(&crypt_target);
1065
1066         if (r < 0)
1067                 DMERR("unregister failed %d", r);
1068
1069         kmem_cache_destroy(_crypt_io_pool);
1070 }
1071
1072 module_init(dm_crypt_init);
1073 module_exit(dm_crypt_exit);
1074
1075 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1076 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1077 MODULE_LICENSE("GPL");