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         /*
  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 dm_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  * null: the initial vector is always zero.  Provides compatibility with
 125  *       obsolete loop_fish2 devices.  Do not use for new devices.
 126  *
 127  * plumb: unimplemented, see:
 128  * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 129  */
 130
 131 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 132 {
 133         memset(iv, 0, cc->iv_size);
 134         *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
 135
 136         return 0;
 137 }
 138
 139 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 140                               const char *opts)
 141 {
 142         struct crypto_cipher *essiv_tfm;
 143         struct crypto_hash *hash_tfm;
 144         struct hash_desc desc;
 145         struct scatterlist sg;
 146         unsigned int saltsize;
 147         u8 *salt;
 148         int err;
 149
 150         if (opts == NULL) {
 151                 ti->error = "Digest algorithm missing for ESSIV mode";
 152                 return -EINVAL;
 153         }
 154
 155         /* Hash the cipher key with the given hash algorithm */
 156         hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
 157         if (IS_ERR(hash_tfm)) {
 158                 ti->error = "Error initializing ESSIV hash";
 159                 return PTR_ERR(hash_tfm);
 160         }
 161
 162         saltsize = crypto_hash_digestsize(hash_tfm);
 163         salt = kmalloc(saltsize, GFP_KERNEL);
 164         if (salt == NULL) {
 165                 ti->error = "Error kmallocing salt storage in ESSIV";
 166                 crypto_free_hash(hash_tfm);
 167                 return -ENOMEM;
 168         }
 169
 170         sg_set_buf(&sg, cc->key, cc->key_size);
 171         desc.tfm = hash_tfm;
 172         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 173         err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
 174         crypto_free_hash(hash_tfm);
 175
 176         if (err) {
 177                 ti->error = "Error calculating hash in ESSIV";
 178                 return err;
 179         }
 180
 181         /* Setup the essiv_tfm with the given salt */
 182         essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 183         if (IS_ERR(essiv_tfm)) {
 184                 ti->error = "Error allocating crypto tfm for ESSIV";
 185                 kfree(salt);
 186                 return PTR_ERR(essiv_tfm);
 187         }
 188         if (crypto_cipher_blocksize(essiv_tfm) !=
 189             crypto_blkcipher_ivsize(cc->tfm)) {
 190                 ti->error = "Block size of ESSIV cipher does "
 191                                 "not match IV size of block cipher";
 192                 crypto_free_cipher(essiv_tfm);
 193                 kfree(salt);
 194                 return -EINVAL;
 195         }
 196         err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
 197         if (err) {
 198                 ti->error = "Failed to set key for ESSIV cipher";
 199                 crypto_free_cipher(essiv_tfm);
 200                 kfree(salt);
 201                 return err;
 202         }
 203         kfree(salt);
 204
 205         cc->iv_gen_private.essiv_tfm = essiv_tfm;
 206         return 0;
 207 }
 208
 209 static void crypt_iv_essiv_dtr(struct crypt_config *cc)
 210 {
 211         crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
 212         cc->iv_gen_private.essiv_tfm = NULL;
 213 }
 214
 215 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 216 {
 217         memset(iv, 0, cc->iv_size);
 218         *(u64 *)iv = cpu_to_le64(sector);
 219         crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
 220         return 0;
 221 }
 222
 223 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
 224                               const char *opts)
 225 {
 226         unsigned int bs = crypto_blkcipher_blocksize(cc->tfm);
 227         int log = ilog2(bs);
 228
 229         /* we need to calculate how far we must shift the sector count
 230          * to get the cipher block count, we use this shift in _gen */
 231
 232         if (1 << log != bs) {
 233                 ti->error = "cypher blocksize is not a power of 2";
 234                 return -EINVAL;
 235         }
 236
 237         if (log > 9) {
 238                 ti->error = "cypher blocksize is > 512";
 239                 return -EINVAL;
 240         }
 241
 242         cc->iv_gen_private.benbi_shift = 9 - log;
 243
 244         return 0;
 245 }
 246
 247 static void crypt_iv_benbi_dtr(struct crypt_config *cc)
 248 {
 249 }
 250
 251 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 252 {
 253         __be64 val;
 254
 255         memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
 256
 257         val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
 258         put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
 259
 260         return 0;
 261 }
 262
 263 static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 264 {
 265         memset(iv, 0, cc->iv_size);
 266
 267         return 0;
 268 }
 269
 270 static struct crypt_iv_operations crypt_iv_plain_ops = {
 271         .generator = crypt_iv_plain_gen
 272 };
 273
 274 static struct crypt_iv_operations crypt_iv_essiv_ops = {
 275         .ctr       = crypt_iv_essiv_ctr,
 276         .dtr       = crypt_iv_essiv_dtr,
 277         .generator = crypt_iv_essiv_gen
 278 };
 279
 280 static struct crypt_iv_operations crypt_iv_benbi_ops = {
 281         .ctr       = crypt_iv_benbi_ctr,
 282         .dtr       = crypt_iv_benbi_dtr,
 283         .generator = crypt_iv_benbi_gen
 284 };
 285
 286 static struct crypt_iv_operations crypt_iv_null_ops = {
 287         .generator = crypt_iv_null_gen
 288 };
 289
 290 static int
 291 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
 292                           struct scatterlist *in, unsigned int length,
 293                           int write, sector_t sector)
 294 {
 295         u8 iv[cc->iv_size] __attribute__ ((aligned(__alignof__(u64))));
 296         struct blkcipher_desc desc = {
 297                 .tfm = cc->tfm,
 298                 .info = iv,
 299                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP,
 300         };
 301         int r;
 302
 303         if (cc->iv_gen_ops) {
 304                 r = cc->iv_gen_ops->generator(cc, iv, sector);
 305                 if (r < 0)
 306                         return r;
 307
 308                 if (write)
 309                         r = crypto_blkcipher_encrypt_iv(&desc, out, in, length);
 310                 else
 311                         r = crypto_blkcipher_decrypt_iv(&desc, out, in, length);
 312         } else {
 313                 if (write)
 314                         r = crypto_blkcipher_encrypt(&desc, out, in, length);
 315                 else
 316                         r = crypto_blkcipher_decrypt(&desc, out, in, length);
 317         }
 318
 319         return r;
 320 }
 321
 322 static void
 323 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
 324                    struct bio *bio_out, struct bio *bio_in,
 325                    sector_t sector, int write)
 326 {
 327         ctx->bio_in = bio_in;
 328         ctx->bio_out = bio_out;
 329         ctx->offset_in = 0;
 330         ctx->offset_out = 0;
 331         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
 332         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
 333         ctx->sector = sector + cc->iv_offset;
 334         ctx->write = write;
 335 }
 336
 337 /*
 338  * Encrypt / decrypt data from one bio to another one (can be the same one)
 339  */
 340 static int crypt_convert(struct crypt_config *cc,
 341                          struct convert_context *ctx)
 342 {
 343         int r = 0;
 344
 345         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 346               ctx->idx_out < ctx->bio_out->bi_vcnt) {
 347                 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 348                 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 349                 struct scatterlist sg_in = {
 350                         .page = bv_in->bv_page,
 351                         .offset = bv_in->bv_offset + ctx->offset_in,
 352                         .length = 1 << SECTOR_SHIFT
 353                 };
 354                 struct scatterlist sg_out = {
 355                         .page = bv_out->bv_page,
 356                         .offset = bv_out->bv_offset + ctx->offset_out,
 357                         .length = 1 << SECTOR_SHIFT
 358                 };
 359
 360                 ctx->offset_in += sg_in.length;
 361                 if (ctx->offset_in >= bv_in->bv_len) {
 362                         ctx->offset_in = 0;
 363                         ctx->idx_in++;
 364                 }
 365
 366                 ctx->offset_out += sg_out.length;
 367                 if (ctx->offset_out >= bv_out->bv_len) {
 368                         ctx->offset_out = 0;
 369                         ctx->idx_out++;
 370                 }
 371
 372                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 373                                               ctx->write, ctx->sector);
 374                 if (r < 0)
 375                         break;
 376
 377                 ctx->sector++;
 378         }
 379
 380         return r;
 381 }
 382
 383  static void dm_crypt_bio_destructor(struct bio *bio)
 384  {
 385         struct dm_crypt_io *io = bio->bi_private;
 386         struct crypt_config *cc = io->target->private;
 387
 388         bio_free(bio, cc->bs);
 389  }
 390
 391 /*
 392  * Generate a new unfragmented bio with the given size
 393  * This should never violate the device limitations
 394  * May return a smaller bio when running out of pages
 395  */
 396 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
 397 {
 398         struct crypt_config *cc = io->target->private;
 399         struct bio *clone;
 400         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 401         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 402         unsigned int i;
 403
 404         clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
 405         if (!clone)
 406                 return NULL;
 407
 408         clone_init(io, clone);
 409
 410         for (i = 0; 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 == (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         return clone;
 442 }
 443
 444 static void crypt_free_buffer_pages(struct crypt_config *cc,
 445                                     struct bio *clone, unsigned int bytes)
 446 {
 447         unsigned int i, start, end;
 448         struct bio_vec *bv;
 449
 450         /*
 451          * This is ugly, but Jens Axboe thinks that using bi_idx in the
 452          * endio function is too dangerous at the moment, so I calculate the
 453          * correct position using bi_vcnt and bi_size.
 454          * The bv_offset and bv_len fields might already be modified but we
 455          * know that we always allocated whole pages.
 456          * A fix to the bi_idx issue in the kernel is in the works, so
 457          * we will hopefully be able to revert to the cleaner solution soon.
 458          */
 459         i = clone->bi_vcnt - 1;
 460         bv = bio_iovec_idx(clone, i);
 461         end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - clone->bi_size;
 462         start = end - bytes;
 463
 464         start >>= PAGE_SHIFT;
 465         if (!clone->bi_size)
 466                 end = clone->bi_vcnt;
 467         else
 468                 end >>= PAGE_SHIFT;
 469
 470         for (i = start; i < end; i++) {
 471                 bv = bio_iovec_idx(clone, i);
 472                 BUG_ON(!bv->bv_page);
 473                 mempool_free(bv->bv_page, cc->page_pool);
 474                 bv->bv_page = NULL;
 475         }
 476 }
 477
 478 /*
 479  * One of the bios was finished. Check for completion of
 480  * the whole request and correctly clean up the buffer.
 481  */
 482 static void dec_pending(struct dm_crypt_io *io, int error)
 483 {
 484         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 485
 486         if (error < 0)
 487                 io->error = error;
 488
 489         if (!atomic_dec_and_test(&io->pending))
 490                 return;
 491
 492         bio_endio(io->base_bio, io->error);
 493
 494         mempool_free(io, cc->io_pool);
 495 }
 496
 497 /*
 498  * kcryptd:
 499  *
 500  * Needed because it would be very unwise to do decryption in an
 501  * interrupt context.
 502  */
 503 static struct workqueue_struct *_kcryptd_workqueue;
 504 static void kcryptd_do_work(struct work_struct *work);
 505
 506 static void kcryptd_queue_io(struct dm_crypt_io *io)
 507 {
 508         INIT_WORK(&io->work, kcryptd_do_work);
 509         queue_work(_kcryptd_workqueue, &io->work);
 510 }
 511
 512 static void crypt_endio(struct bio *clone, int error)
 513 {
 514         struct dm_crypt_io *io = clone->bi_private;
 515         struct crypt_config *cc = io->target->private;
 516         unsigned read_io = bio_data_dir(clone) == READ;
 517
 518         /*
 519          * free the processed pages
 520          */
 521         if (!read_io) {
 522                 crypt_free_buffer_pages(cc, clone, clone->bi_size);
 523                 goto out;
 524         }
 525
 526         if (unlikely(!bio_flagged(clone, BIO_UPTODATE))) {
 527                 error = -EIO;
 528                 goto out;
 529         }
 530
 531         bio_put(clone);
 532         io->post_process = 1;
 533         kcryptd_queue_io(io);
 534         return;
 535
 536 out:
 537         bio_put(clone);
 538         dec_pending(io, error);
 539 }
 540
 541 static void clone_init(struct dm_crypt_io *io, struct bio *clone)
 542 {
 543         struct crypt_config *cc = io->target->private;
 544
 545         clone->bi_private = io;
 546         clone->bi_end_io  = crypt_endio;
 547         clone->bi_bdev    = cc->dev->bdev;
 548         clone->bi_rw      = io->base_bio->bi_rw;
 549         clone->bi_destructor = dm_crypt_bio_destructor;
 550 }
 551
 552 static void process_read(struct dm_crypt_io *io)
 553 {
 554         struct crypt_config *cc = io->target->private;
 555         struct bio *base_bio = io->base_bio;
 556         struct bio *clone;
 557         sector_t sector = base_bio->bi_sector - io->target->begin;
 558
 559         atomic_inc(&io->pending);
 560
 561         /*
 562          * The block layer might modify the bvec array, so always
 563          * copy the required bvecs because we need the original
 564          * one in order to decrypt the whole bio data *afterwards*.
 565          */
 566         clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
 567         if (unlikely(!clone)) {
 568                 dec_pending(io, -ENOMEM);
 569                 return;
 570         }
 571
 572         clone_init(io, clone);
 573         clone->bi_idx = 0;
 574         clone->bi_vcnt = bio_segments(base_bio);
 575         clone->bi_size = base_bio->bi_size;
 576         clone->bi_sector = cc->start + sector;
 577         memcpy(clone->bi_io_vec, bio_iovec(base_bio),
 578                sizeof(struct bio_vec) * clone->bi_vcnt);
 579
 580         generic_make_request(clone);
 581 }
 582
 583 static void process_write(struct dm_crypt_io *io)
 584 {
 585         struct crypt_config *cc = io->target->private;
 586         struct bio *base_bio = io->base_bio;
 587         struct bio *clone;
 588         struct convert_context ctx;
 589         unsigned remaining = base_bio->bi_size;
 590         sector_t sector = base_bio->bi_sector - io->target->begin;
 591
 592         atomic_inc(&io->pending);
 593
 594         crypt_convert_init(cc, &ctx, NULL, base_bio, sector, 1);
 595
 596         /*
 597          * The allocated buffers can be smaller than the whole bio,
 598          * so repeat the whole process until all the data can be handled.
 599          */
 600         while (remaining) {
 601                 clone = crypt_alloc_buffer(io, remaining);
 602                 if (unlikely(!clone)) {
 603                         dec_pending(io, -ENOMEM);
 604                         return;
 605                 }
 606
 607                 ctx.bio_out = clone;
 608                 ctx.idx_out = 0;
 609
 610                 if (unlikely(crypt_convert(cc, &ctx) < 0)) {
 611                         crypt_free_buffer_pages(cc, clone, clone->bi_size);
 612                         bio_put(clone);
 613                         dec_pending(io, -EIO);
 614                         return;
 615                 }
 616
 617                 /* crypt_convert should have filled the clone bio */
 618                 BUG_ON(ctx.idx_out < clone->bi_vcnt);
 619
 620                 clone->bi_sector = cc->start + sector;
 621                 remaining -= clone->bi_size;
 622                 sector += bio_sectors(clone);
 623
 624                 /* Grab another reference to the io struct
 625                  * before we kick off the request */
 626                 if (remaining)
 627                         atomic_inc(&io->pending);
 628
 629                 generic_make_request(clone);
 630
 631                 /* Do not reference clone after this - it
 632                  * may be gone already. */
 633
 634                 /* out of memory -> run queues */
 635                 if (remaining)
 636                         congestion_wait(WRITE, HZ/100);
 637         }
 638 }
 639
 640 static void process_read_endio(struct dm_crypt_io *io)
 641 {
 642         struct crypt_config *cc = io->target->private;
 643         struct convert_context ctx;
 644
 645         crypt_convert_init(cc, &ctx, io->base_bio, io->base_bio,
 646                            io->base_bio->bi_sector - io->target->begin, 0);
 647
 648         dec_pending(io, crypt_convert(cc, &ctx));
 649 }
 650
 651 static void kcryptd_do_work(struct work_struct *work)
 652 {
 653         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 654
 655         if (io->post_process)
 656                 process_read_endio(io);
 657         else if (bio_data_dir(io->base_bio) == READ)
 658                 process_read(io);
 659         else
 660                 process_write(io);
 661 }
 662
 663 /*
 664  * Decode key from its hex representation
 665  */
 666 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 667 {
 668         char buffer[3];
 669         char *endp;
 670         unsigned int i;
 671
 672         buffer[2] = '\0';
 673
 674         for (i = 0; i < size; i++) {
 675                 buffer[0] = *hex++;
 676                 buffer[1] = *hex++;
 677
 678                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 679
 680                 if (endp != &buffer[2])
 681                         return -EINVAL;
 682         }
 683
 684         if (*hex != '\0')
 685                 return -EINVAL;
 686
 687         return 0;
 688 }
 689
 690 /*
 691  * Encode key into its hex representation
 692  */
 693 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
 694 {
 695         unsigned int i;
 696
 697         for (i = 0; i < size; i++) {
 698                 sprintf(hex, "%02x", *key);
 699                 hex += 2;
 700                 key++;
 701         }
 702 }
 703
 704 static int crypt_set_key(struct crypt_config *cc, char *key)
 705 {
 706         unsigned key_size = strlen(key) >> 1;
 707
 708         if (cc->key_size && cc->key_size != key_size)
 709                 return -EINVAL;
 710
 711         cc->key_size = key_size; /* initial settings */
 712
 713         if ((!key_size && strcmp(key, "-")) ||
 714             (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
 715                 return -EINVAL;
 716
 717         set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 718
 719         return 0;
 720 }
 721
 722 static int crypt_wipe_key(struct crypt_config *cc)
 723 {
 724         clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 725         memset(&cc->key, 0, cc->key_size * sizeof(u8));
 726         return 0;
 727 }
 728
 729 /*
 730  * Construct an encryption mapping:
 731  * <cipher> <key> <iv_offset> <dev_path> <start>
 732  */
 733 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 734 {
 735         struct crypt_config *cc;
 736         struct crypto_blkcipher *tfm;
 737         char *tmp;
 738         char *cipher;
 739         char *chainmode;
 740         char *ivmode;
 741         char *ivopts;
 742         unsigned int key_size;
 743         unsigned long long tmpll;
 744
 745         if (argc != 5) {
 746                 ti->error = "Not enough arguments";
 747                 return -EINVAL;
 748         }
 749
 750         tmp = argv[0];
 751         cipher = strsep(&tmp, "-");
 752         chainmode = strsep(&tmp, "-");
 753         ivopts = strsep(&tmp, "-");
 754         ivmode = strsep(&ivopts, ":");
 755
 756         if (tmp)
 757                 DMWARN("Unexpected additional cipher options");
 758
 759         key_size = strlen(argv[1]) >> 1;
 760
 761         cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 762         if (cc == NULL) {
 763                 ti->error =
 764                         "Cannot allocate transparent encryption context";
 765                 return -ENOMEM;
 766         }
 767
 768         if (crypt_set_key(cc, argv[1])) {
 769                 ti->error = "Error decoding key";
 770                 goto bad1;
 771         }
 772
 773         /* Compatiblity mode for old dm-crypt cipher strings */
 774         if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 775                 chainmode = "cbc";
 776                 ivmode = "plain";
 777         }
 778
 779         if (strcmp(chainmode, "ecb") && !ivmode) {
 780                 ti->error = "This chaining mode requires an IV mechanism";
 781                 goto bad1;
 782         }
 783
 784         if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", chainmode,
 785                      cipher) >= CRYPTO_MAX_ALG_NAME) {
 786                 ti->error = "Chain mode + cipher name is too long";
 787                 goto bad1;
 788         }
 789
 790         tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 791         if (IS_ERR(tfm)) {
 792                 ti->error = "Error allocating crypto tfm";
 793                 goto bad1;
 794         }
 795
 796         strcpy(cc->cipher, cipher);
 797         strcpy(cc->chainmode, chainmode);
 798         cc->tfm = tfm;
 799
 800         /*
 801          * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
 802          * See comments at iv code
 803          */
 804
 805         if (ivmode == NULL)
 806                 cc->iv_gen_ops = NULL;
 807         else if (strcmp(ivmode, "plain") == 0)
 808                 cc->iv_gen_ops = &crypt_iv_plain_ops;
 809         else if (strcmp(ivmode, "essiv") == 0)
 810                 cc->iv_gen_ops = &crypt_iv_essiv_ops;
 811         else if (strcmp(ivmode, "benbi") == 0)
 812                 cc->iv_gen_ops = &crypt_iv_benbi_ops;
 813         else if (strcmp(ivmode, "null") == 0)
 814                 cc->iv_gen_ops = &crypt_iv_null_ops;
 815         else {
 816                 ti->error = "Invalid IV mode";
 817                 goto bad2;
 818         }
 819
 820         if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
 821             cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
 822                 goto bad2;
 823
 824         cc->iv_size = crypto_blkcipher_ivsize(tfm);
 825         if (cc->iv_size)
 826                 /* at least a 64 bit sector number should fit in our buffer */
 827                 cc->iv_size = max(cc->iv_size,
 828                                   (unsigned int)(sizeof(u64) / sizeof(u8)));
 829         else {
 830                 if (cc->iv_gen_ops) {
 831                         DMWARN("Selected cipher does not support IVs");
 832                         if (cc->iv_gen_ops->dtr)
 833                                 cc->iv_gen_ops->dtr(cc);
 834                         cc->iv_gen_ops = NULL;
 835                 }
 836         }
 837
 838         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
 839         if (!cc->io_pool) {
 840                 ti->error = "Cannot allocate crypt io mempool";
 841                 goto bad3;
 842         }
 843
 844         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
 845         if (!cc->page_pool) {
 846                 ti->error = "Cannot allocate page mempool";
 847                 goto bad4;
 848         }
 849
 850         cc->bs = bioset_create(MIN_IOS, MIN_IOS);
 851         if (!cc->bs) {
 852                 ti->error = "Cannot allocate crypt bioset";
 853                 goto bad_bs;
 854         }
 855
 856         if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
 857                 ti->error = "Error setting key";
 858                 goto bad5;
 859         }
 860
 861         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 862                 ti->error = "Invalid iv_offset sector";
 863                 goto bad5;
 864         }
 865         cc->iv_offset = tmpll;
 866
 867         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
 868                 ti->error = "Invalid device sector";
 869                 goto bad5;
 870         }
 871         cc->start = tmpll;
 872
 873         if (dm_get_device(ti, argv[3], cc->start, ti->len,
 874                           dm_table_get_mode(ti->table), &cc->dev)) {
 875                 ti->error = "Device lookup failed";
 876                 goto bad5;
 877         }
 878
 879         if (ivmode && cc->iv_gen_ops) {
 880                 if (ivopts)
 881                         *(ivopts - 1) = ':';
 882                 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
 883                 if (!cc->iv_mode) {
 884                         ti->error = "Error kmallocing iv_mode string";
 885                         goto bad5;
 886                 }
 887                 strcpy(cc->iv_mode, ivmode);
 888         } else
 889                 cc->iv_mode = NULL;
 890
 891         ti->private = cc;
 892         return 0;
 893
 894 bad5:
 895         bioset_free(cc->bs);
 896 bad_bs:
 897         mempool_destroy(cc->page_pool);
 898 bad4:
 899         mempool_destroy(cc->io_pool);
 900 bad3:
 901         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 902                 cc->iv_gen_ops->dtr(cc);
 903 bad2:
 904         crypto_free_blkcipher(tfm);
 905 bad1:
 906         /* Must zero key material before freeing */
 907         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 908         kfree(cc);
 909         return -EINVAL;
 910 }
 911
 912 static void crypt_dtr(struct dm_target *ti)
 913 {
 914         struct crypt_config *cc = (struct crypt_config *) ti->private;
 915
 916         flush_workqueue(_kcryptd_workqueue);
 917
 918         bioset_free(cc->bs);
 919         mempool_destroy(cc->page_pool);
 920         mempool_destroy(cc->io_pool);
 921
 922         kfree(cc->iv_mode);
 923         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 924                 cc->iv_gen_ops->dtr(cc);
 925         crypto_free_blkcipher(cc->tfm);
 926         dm_put_device(ti, cc->dev);
 927
 928         /* Must zero key material before freeing */
 929         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 930         kfree(cc);
 931 }
 932
 933 static int crypt_map(struct dm_target *ti, struct bio *bio,
 934                      union map_info *map_context)
 935 {
 936         struct crypt_config *cc = ti->private;
 937         struct dm_crypt_io *io;
 938
 939         io = mempool_alloc(cc->io_pool, GFP_NOIO);
 940         io->target = ti;
 941         io->base_bio = bio;
 942         io->error = io->post_process = 0;
 943         atomic_set(&io->pending, 0);
 944         kcryptd_queue_io(io);
 945
 946         return DM_MAPIO_SUBMITTED;
 947 }
 948
 949 static int crypt_status(struct dm_target *ti, status_type_t type,
 950                         char *result, unsigned int maxlen)
 951 {
 952         struct crypt_config *cc = (struct crypt_config *) ti->private;
 953         unsigned int sz = 0;
 954
 955         switch (type) {
 956         case STATUSTYPE_INFO:
 957                 result[0] = '\0';
 958                 break;
 959
 960         case STATUSTYPE_TABLE:
 961                 if (cc->iv_mode)
 962                         DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
 963                                cc->iv_mode);
 964                 else
 965                         DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
 966
 967                 if (cc->key_size > 0) {
 968                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
 969                                 return -ENOMEM;
 970
 971                         crypt_encode_key(result + sz, cc->key, cc->key_size);
 972                         sz += cc->key_size << 1;
 973                 } else {
 974                         if (sz >= maxlen)
 975                                 return -ENOMEM;
 976                         result[sz++] = '-';
 977                 }
 978
 979                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
 980                                 cc->dev->name, (unsigned long long)cc->start);
 981                 break;
 982         }
 983         return 0;
 984 }
 985
 986 static void crypt_postsuspend(struct dm_target *ti)
 987 {
 988         struct crypt_config *cc = ti->private;
 989
 990         set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
 991 }
 992
 993 static int crypt_preresume(struct dm_target *ti)
 994 {
 995         struct crypt_config *cc = ti->private;
 996
 997         if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
 998                 DMERR("aborting resume - crypt key is not set.");
 999                 return -EAGAIN;
1000         }
1001
1002         return 0;
1003 }
1004
1005 static void crypt_resume(struct dm_target *ti)
1006 {
1007         struct crypt_config *cc = ti->private;
1008
1009         clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1010 }
1011
1012 /* Message interface
1013  *      key set <key>
1014  *      key wipe
1015  */
1016 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1017 {
1018         struct crypt_config *cc = ti->private;
1019
1020         if (argc < 2)
1021                 goto error;
1022
1023         if (!strnicmp(argv[0], MESG_STR("key"))) {
1024                 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1025                         DMWARN("not suspended during key manipulation.");
1026                         return -EINVAL;
1027                 }
1028                 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1029                         return crypt_set_key(cc, argv[2]);
1030                 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1031                         return crypt_wipe_key(cc);
1032         }
1033
1034 error:
1035         DMWARN("unrecognised message received.");
1036         return -EINVAL;
1037 }
1038
1039 static struct target_type crypt_target = {
1040         .name   = "crypt",
1041         .version= {1, 5, 0},
1042         .module = THIS_MODULE,
1043         .ctr    = crypt_ctr,
1044         .dtr    = crypt_dtr,
1045         .map    = crypt_map,
1046         .status = crypt_status,
1047         .postsuspend = crypt_postsuspend,
1048         .preresume = crypt_preresume,
1049         .resume = crypt_resume,
1050         .message = crypt_message,
1051 };
1052
1053 static int __init dm_crypt_init(void)
1054 {
1055         int r;
1056
1057         _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
1058         if (!_crypt_io_pool)
1059                 return -ENOMEM;
1060
1061         _kcryptd_workqueue = create_workqueue("kcryptd");
1062         if (!_kcryptd_workqueue) {
1063                 r = -ENOMEM;
1064                 DMERR("couldn't create kcryptd");
1065                 goto bad1;
1066         }
1067
1068         r = dm_register_target(&crypt_target);
1069         if (r < 0) {
1070                 DMERR("register failed %d", r);
1071                 goto bad2;
1072         }
1073
1074         return 0;
1075
1076 bad2:
1077         destroy_workqueue(_kcryptd_workqueue);
1078 bad1:
1079         kmem_cache_destroy(_crypt_io_pool);
1080         return r;
1081 }
1082
1083 static void __exit dm_crypt_exit(void)
1084 {
1085         int r = dm_unregister_target(&crypt_target);
1086
1087         if (r < 0)
1088                 DMERR("unregister failed %d", r);
1089
1090         destroy_workqueue(_kcryptd_workqueue);
1091         kmem_cache_destroy(_crypt_io_pool);
1092 }
1093
1094 module_init(dm_crypt_init);
1095 module_exit(dm_crypt_exit);
1096
1097 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1098 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1099 MODULE_LICENSE("GPL");