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) 2006-2007 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  * context holding the current state of a multi-part conversion
  32  */
  33 struct convert_context {
  34         struct bio *bio_in;
  35         struct bio *bio_out;
  36         unsigned int offset_in;
  37         unsigned int offset_out;
  38         unsigned int idx_in;
  39         unsigned int idx_out;
  40         sector_t sector;
  41 };
  42
  43 /*
  44  * per bio private data
  45  */
  46 struct dm_crypt_io {
  47         struct dm_target *target;
  48         struct bio *base_bio;
  49         struct work_struct work;
  50
  51         struct convert_context ctx;
  52
  53         atomic_t pending;
  54         int error;
  55         sector_t sector;
  56 };
  57
  58 struct crypt_config;
  59
  60 struct crypt_iv_operations {
  61         int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
  62                    const char *opts);
  63         void (*dtr)(struct crypt_config *cc);
  64         const char *(*status)(struct crypt_config *cc);
  65         int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
  66 };
  67
  68 /*
  69  * Crypt: maps a linear range of a block device
  70  * and encrypts / decrypts at the same time.
  71  */
  72 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
  73 struct crypt_config {
  74         struct dm_dev *dev;
  75         sector_t start;
  76
  77         /*
  78          * pool for per bio private data and
  79          * for encryption buffer pages
  80          */
  81         mempool_t *io_pool;
  82         mempool_t *page_pool;
  83         struct bio_set *bs;
  84
  85         struct workqueue_struct *io_queue;
  86         struct workqueue_struct *crypt_queue;
  87         /*
  88          * crypto related data
  89          */
  90         struct crypt_iv_operations *iv_gen_ops;
  91         char *iv_mode;
  92         union {
  93                 struct crypto_cipher *essiv_tfm;
  94                 int benbi_shift;
  95         } iv_gen_private;
  96         sector_t iv_offset;
  97         unsigned int iv_size;
  98
  99         char cipher[CRYPTO_MAX_ALG_NAME];
 100         char chainmode[CRYPTO_MAX_ALG_NAME];
 101         struct crypto_blkcipher *tfm;
 102         unsigned long flags;
 103         unsigned int key_size;
 104         u8 key[0];
 105 };
 106
 107 #define MIN_IOS        16
 108 #define MIN_POOL_PAGES 32
 109 #define MIN_BIO_PAGES  8
 110
 111 static struct kmem_cache *_crypt_io_pool;
 112
 113 static void clone_init(struct dm_crypt_io *, struct bio *);
 114
 115 /*
 116  * Different IV generation algorithms:
 117  *
 118  * plain: the initial vector is the 32-bit little-endian version of the sector
 119  *        number, padded with zeros if necessary.
 120  *
 121  * essiv: "encrypted sector|salt initial vector", the sector number is
 122  *        encrypted with the bulk cipher using a salt as key. The salt
 123  *        should be derived from the bulk cipher's key via hashing.
 124  *
 125  * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
 126  *        (needed for LRW-32-AES and possible other narrow block modes)
 127  *
 128  * null: the initial vector is always zero.  Provides compatibility with
 129  *       obsolete loop_fish2 devices.  Do not use for new devices.
 130  *
 131  * plumb: unimplemented, see:
 132  * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
 133  */
 134
 135 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 136 {
 137         memset(iv, 0, cc->iv_size);
 138         *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
 139
 140         return 0;
 141 }
 142
 143 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 144                               const char *opts)
 145 {
 146         struct crypto_cipher *essiv_tfm;
 147         struct crypto_hash *hash_tfm;
 148         struct hash_desc desc;
 149         struct scatterlist sg;
 150         unsigned int saltsize;
 151         u8 *salt;
 152         int err;
 153
 154         if (opts == NULL) {
 155                 ti->error = "Digest algorithm missing for ESSIV mode";
 156                 return -EINVAL;
 157         }
 158
 159         /* Hash the cipher key with the given hash algorithm */
 160         hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
 161         if (IS_ERR(hash_tfm)) {
 162                 ti->error = "Error initializing ESSIV hash";
 163                 return PTR_ERR(hash_tfm);
 164         }
 165
 166         saltsize = crypto_hash_digestsize(hash_tfm);
 167         salt = kmalloc(saltsize, GFP_KERNEL);
 168         if (salt == NULL) {
 169                 ti->error = "Error kmallocing salt storage in ESSIV";
 170                 crypto_free_hash(hash_tfm);
 171                 return -ENOMEM;
 172         }
 173
 174         sg_init_one(&sg, cc->key, cc->key_size);
 175         desc.tfm = hash_tfm;
 176         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 177         err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
 178         crypto_free_hash(hash_tfm);
 179
 180         if (err) {
 181                 ti->error = "Error calculating hash in ESSIV";
 182                 kfree(salt);
 183                 return err;
 184         }
 185
 186         /* Setup the essiv_tfm with the given salt */
 187         essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 188         if (IS_ERR(essiv_tfm)) {
 189                 ti->error = "Error allocating crypto tfm for ESSIV";
 190                 kfree(salt);
 191                 return PTR_ERR(essiv_tfm);
 192         }
 193         if (crypto_cipher_blocksize(essiv_tfm) !=
 194             crypto_blkcipher_ivsize(cc->tfm)) {
 195                 ti->error = "Block size of ESSIV cipher does "
 196                             "not match IV size of block cipher";
 197                 crypto_free_cipher(essiv_tfm);
 198                 kfree(salt);
 199                 return -EINVAL;
 200         }
 201         err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
 202         if (err) {
 203                 ti->error = "Failed to set key for ESSIV cipher";
 204                 crypto_free_cipher(essiv_tfm);
 205                 kfree(salt);
 206                 return err;
 207         }
 208         kfree(salt);
 209
 210         cc->iv_gen_private.essiv_tfm = essiv_tfm;
 211         return 0;
 212 }
 213
 214 static void crypt_iv_essiv_dtr(struct crypt_config *cc)
 215 {
 216         crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
 217         cc->iv_gen_private.essiv_tfm = NULL;
 218 }
 219
 220 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 221 {
 222         memset(iv, 0, cc->iv_size);
 223         *(u64 *)iv = cpu_to_le64(sector);
 224         crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
 225         return 0;
 226 }
 227
 228 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
 229                               const char *opts)
 230 {
 231         unsigned int bs = crypto_blkcipher_blocksize(cc->tfm);
 232         int log = ilog2(bs);
 233
 234         /* we need to calculate how far we must shift the sector count
 235          * to get the cipher block count, we use this shift in _gen */
 236
 237         if (1 << log != bs) {
 238                 ti->error = "cypher blocksize is not a power of 2";
 239                 return -EINVAL;
 240         }
 241
 242         if (log > 9) {
 243                 ti->error = "cypher blocksize is > 512";
 244                 return -EINVAL;
 245         }
 246
 247         cc->iv_gen_private.benbi_shift = 9 - log;
 248
 249         return 0;
 250 }
 251
 252 static void crypt_iv_benbi_dtr(struct crypt_config *cc)
 253 {
 254 }
 255
 256 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 257 {
 258         __be64 val;
 259
 260         memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
 261
 262         val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
 263         put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));
 264
 265         return 0;
 266 }
 267
 268 static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
 269 {
 270         memset(iv, 0, cc->iv_size);
 271
 272         return 0;
 273 }
 274
 275 static struct crypt_iv_operations crypt_iv_plain_ops = {
 276         .generator = crypt_iv_plain_gen
 277 };
 278
 279 static struct crypt_iv_operations crypt_iv_essiv_ops = {
 280         .ctr       = crypt_iv_essiv_ctr,
 281         .dtr       = crypt_iv_essiv_dtr,
 282         .generator = crypt_iv_essiv_gen
 283 };
 284
 285 static struct crypt_iv_operations crypt_iv_benbi_ops = {
 286         .ctr       = crypt_iv_benbi_ctr,
 287         .dtr       = crypt_iv_benbi_dtr,
 288         .generator = crypt_iv_benbi_gen
 289 };
 290
 291 static struct crypt_iv_operations crypt_iv_null_ops = {
 292         .generator = crypt_iv_null_gen
 293 };
 294
 295 static void crypt_read_io_done(struct dm_crypt_io *io, int error);
 296 static void crypt_write_io_done(struct dm_crypt_io *io, int error);
 297
 298 static int
 299 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
 300                           struct scatterlist *in, unsigned int length,
 301                           int write, sector_t sector)
 302 {
 303         u8 iv[cc->iv_size] __attribute__ ((aligned(__alignof__(u64))));
 304         struct blkcipher_desc desc = {
 305                 .tfm = cc->tfm,
 306                 .info = iv,
 307                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP,
 308         };
 309         int r;
 310
 311         if (cc->iv_gen_ops) {
 312                 r = cc->iv_gen_ops->generator(cc, iv, sector);
 313                 if (r < 0)
 314                         return r;
 315
 316                 if (write)
 317                         r = crypto_blkcipher_encrypt_iv(&desc, out, in, length);
 318                 else
 319                         r = crypto_blkcipher_decrypt_iv(&desc, out, in, length);
 320         } else {
 321                 if (write)
 322                         r = crypto_blkcipher_encrypt(&desc, out, in, length);
 323                 else
 324                         r = crypto_blkcipher_decrypt(&desc, out, in, length);
 325         }
 326
 327         return r;
 328 }
 329
 330 static void crypt_convert_init(struct crypt_config *cc,
 331                                struct convert_context *ctx,
 332                                struct bio *bio_out, struct bio *bio_in,
 333                                sector_t sector)
 334 {
 335         ctx->bio_in = bio_in;
 336         ctx->bio_out = bio_out;
 337         ctx->offset_in = 0;
 338         ctx->offset_out = 0;
 339         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
 340         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
 341         ctx->sector = sector + cc->iv_offset;
 342 }
 343
 344 /*
 345  * Encrypt / decrypt data from one bio to another one (can be the same one)
 346  */
 347 static int crypt_convert(struct crypt_config *cc,
 348                          struct convert_context *ctx)
 349 {
 350         int r = 0;
 351
 352         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 353               ctx->idx_out < ctx->bio_out->bi_vcnt) {
 354                 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 355                 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 356                 struct scatterlist sg_in, sg_out;
 357
 358                 sg_init_table(&sg_in, 1);
 359                 sg_set_page(&sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT, bv_in->bv_offset + ctx->offset_in);
 360
 361                 sg_init_table(&sg_out, 1);
 362                 sg_set_page(&sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT, bv_out->bv_offset + ctx->offset_out);
 363
 364                 ctx->offset_in += sg_in.length;
 365                 if (ctx->offset_in >= bv_in->bv_len) {
 366                         ctx->offset_in = 0;
 367                         ctx->idx_in++;
 368                 }
 369
 370                 ctx->offset_out += sg_out.length;
 371                 if (ctx->offset_out >= bv_out->bv_len) {
 372                         ctx->offset_out = 0;
 373                         ctx->idx_out++;
 374                 }
 375
 376                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 377                                 bio_data_dir(ctx->bio_in) == WRITE, ctx->sector);
 378                 if (r < 0)
 379                         break;
 380
 381                 ctx->sector++;
 382         }
 383
 384         return r;
 385 }
 386
 387 static void dm_crypt_bio_destructor(struct bio *bio)
 388 {
 389         struct dm_crypt_io *io = bio->bi_private;
 390         struct crypt_config *cc = io->target->private;
 391
 392         bio_free(bio, cc->bs);
 393 }
 394
 395 /*
 396  * Generate a new unfragmented bio with the given size
 397  * This should never violate the device limitations
 398  * May return a smaller bio when running out of pages
 399  */
 400 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
 401 {
 402         struct crypt_config *cc = io->target->private;
 403         struct bio *clone;
 404         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 405         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 406         unsigned int i;
 407
 408         clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
 409         if (!clone)
 410                 return NULL;
 411
 412         clone_init(io, clone);
 413
 414         for (i = 0; i < nr_iovecs; i++) {
 415                 struct bio_vec *bv = bio_iovec_idx(clone, i);
 416
 417                 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
 418                 if (!bv->bv_page)
 419                         break;
 420
 421                 /*
 422                  * if additional pages cannot be allocated without waiting,
 423                  * return a partially allocated bio, the caller will then try
 424                  * to allocate additional bios while submitting this partial bio
 425                  */
 426                 if (i == (MIN_BIO_PAGES - 1))
 427                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 428
 429                 bv->bv_offset = 0;
 430                 if (size > PAGE_SIZE)
 431                         bv->bv_len = PAGE_SIZE;
 432                 else
 433                         bv->bv_len = size;
 434
 435                 clone->bi_size += bv->bv_len;
 436                 clone->bi_vcnt++;
 437                 size -= bv->bv_len;
 438         }
 439
 440         if (!clone->bi_size) {
 441                 bio_put(clone);
 442                 return NULL;
 443         }
 444
 445         return clone;
 446 }
 447
 448 static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
 449 {
 450         unsigned int i;
 451         struct bio_vec *bv;
 452
 453         for (i = 0; i < clone->bi_vcnt; i++) {
 454                 bv = bio_iovec_idx(clone, i);
 455                 BUG_ON(!bv->bv_page);
 456                 mempool_free(bv->bv_page, cc->page_pool);
 457                 bv->bv_page = NULL;
 458         }
 459 }
 460
 461 /*
 462  * One of the bios was finished. Check for completion of
 463  * the whole request and correctly clean up the buffer.
 464  */
 465 static void crypt_dec_pending(struct dm_crypt_io *io)
 466 {
 467         struct crypt_config *cc = io->target->private;
 468
 469         if (!atomic_dec_and_test(&io->pending))
 470                 return;
 471
 472         bio_endio(io->base_bio, io->error);
 473         mempool_free(io, cc->io_pool);
 474 }
 475
 476 /*
 477  * kcryptd/kcryptd_io:
 478  *
 479  * Needed because it would be very unwise to do decryption in an
 480  * interrupt context.
 481  *
 482  * kcryptd performs the actual encryption or decryption.
 483  *
 484  * kcryptd_io performs the IO submission.
 485  *
 486  * They must be separated as otherwise the final stages could be
 487  * starved by new requests which can block in the first stages due
 488  * to memory allocation.
 489  */
 490 static void kcryptd_do_io(struct work_struct *work);
 491 static void kcryptd_do_crypt(struct work_struct *work);
 492
 493 static void kcryptd_queue_io(struct dm_crypt_io *io)
 494 {
 495         struct crypt_config *cc = io->target->private;
 496
 497         INIT_WORK(&io->work, kcryptd_do_io);
 498         queue_work(cc->io_queue, &io->work);
 499 }
 500
 501 static void kcryptd_queue_crypt(struct dm_crypt_io *io)
 502 {
 503         struct crypt_config *cc = io->target->private;
 504
 505         INIT_WORK(&io->work, kcryptd_do_crypt);
 506         queue_work(cc->crypt_queue, &io->work);
 507 }
 508
 509 static void crypt_endio(struct bio *clone, int error)
 510 {
 511         struct dm_crypt_io *io = clone->bi_private;
 512         struct crypt_config *cc = io->target->private;
 513         unsigned rw = bio_data_dir(clone);
 514
 515         if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
 516                 error = -EIO;
 517
 518         /*
 519          * free the processed pages
 520          */
 521         if (rw == WRITE)
 522                 crypt_free_buffer_pages(cc, clone);
 523
 524         bio_put(clone);
 525
 526         if (rw == READ && !error) {
 527                 kcryptd_queue_crypt(io);
 528                 return;
 529         }
 530
 531         if (unlikely(error))
 532                 io->error = error;
 533
 534         crypt_dec_pending(io);
 535 }
 536
 537 static void clone_init(struct dm_crypt_io *io, struct bio *clone)
 538 {
 539         struct crypt_config *cc = io->target->private;
 540
 541         clone->bi_private = io;
 542         clone->bi_end_io  = crypt_endio;
 543         clone->bi_bdev    = cc->dev->bdev;
 544         clone->bi_rw      = io->base_bio->bi_rw;
 545         clone->bi_destructor = dm_crypt_bio_destructor;
 546 }
 547
 548 static void crypt_read_io(struct dm_crypt_io *io)
 549 {
 550         struct crypt_config *cc = io->target->private;
 551         struct bio *base_bio = io->base_bio;
 552         struct bio *clone;
 553
 554         atomic_inc(&io->pending);
 555
 556         /*
 557          * The block layer might modify the bvec array, so always
 558          * copy the required bvecs because we need the original
 559          * one in order to decrypt the whole bio data *afterwards*.
 560          */
 561         clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
 562         if (unlikely(!clone)) {
 563                 io->error = -ENOMEM;
 564                 crypt_dec_pending(io);
 565                 return;
 566         }
 567
 568         clone_init(io, clone);
 569         clone->bi_idx = 0;
 570         clone->bi_vcnt = bio_segments(base_bio);
 571         clone->bi_size = base_bio->bi_size;
 572         clone->bi_sector = cc->start + io->sector;
 573         memcpy(clone->bi_io_vec, bio_iovec(base_bio),
 574                sizeof(struct bio_vec) * clone->bi_vcnt);
 575
 576         generic_make_request(clone);
 577 }
 578
 579 static void crypt_write_io(struct dm_crypt_io *io)
 580 {
 581 }
 582
 583 static void crypt_write_io_done(struct dm_crypt_io *io, int error)
 584 {
 585         struct bio *clone = io->ctx.bio_out;
 586         struct crypt_config *cc = io->target->private;
 587
 588         if (unlikely(error < 0)) {
 589                 crypt_free_buffer_pages(cc, clone);
 590                 bio_put(clone);
 591                 io->error = -EIO;
 592                 crypt_dec_pending(io);
 593                 return;
 594         }
 595
 596         /* crypt_convert should have filled the clone bio */
 597         BUG_ON(io->ctx.idx_out < clone->bi_vcnt);
 598
 599         clone->bi_sector = cc->start + io->sector;
 600         io->sector += bio_sectors(clone);
 601 }
 602
 603 static void crypt_write_io_loop(struct dm_crypt_io *io)
 604 {
 605         struct crypt_config *cc = io->target->private;
 606         struct bio *clone;
 607         unsigned remaining = io->base_bio->bi_size;
 608         int r;
 609
 610         /*
 611          * The allocated buffers can be smaller than the whole bio,
 612          * so repeat the whole process until all the data can be handled.
 613          */
 614         while (remaining) {
 615                 clone = crypt_alloc_buffer(io, remaining);
 616                 if (unlikely(!clone)) {
 617                         io->error = -ENOMEM;
 618                         crypt_dec_pending(io);
 619                         return;
 620                 }
 621
 622                 io->ctx.bio_out = clone;
 623                 io->ctx.idx_out = 0;
 624
 625                 remaining -= clone->bi_size;
 626
 627                 r = crypt_convert(cc, &io->ctx);
 628
 629                 crypt_write_io_done(io, r);
 630                 if (unlikely(r < 0))
 631                         return;
 632
 633                 /* Grab another reference to the io struct
 634                  * before we kick off the request */
 635                 if (remaining)
 636                         atomic_inc(&io->pending);
 637
 638                 generic_make_request(clone);
 639
 640                 /* Do not reference clone after this - it
 641                  * may be gone already. */
 642
 643                 /* out of memory -> run queues */
 644                 if (unlikely(remaining))
 645                         congestion_wait(WRITE, HZ/100);
 646         }
 647 }
 648
 649 static void crypt_write_io_process(struct dm_crypt_io *io)
 650 {
 651         struct crypt_config *cc = io->target->private;
 652
 653         atomic_inc(&io->pending);
 654
 655         crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, io->sector);
 656         crypt_write_io_loop(io);
 657 }
 658
 659 static void crypt_read_io_done(struct dm_crypt_io *io, int error)
 660 {
 661         if (unlikely(error < 0))
 662                 io->error = -EIO;
 663
 664         crypt_dec_pending(io);
 665 }
 666
 667 static void crypt_read_io_process(struct dm_crypt_io *io)
 668 {
 669         struct crypt_config *cc = io->target->private;
 670         int r = 0;
 671
 672         crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio, io->sector);
 673
 674         r = crypt_convert(cc, &io->ctx);
 675
 676         crypt_read_io_done(io, r);
 677 }
 678
 679 static void kcryptd_do_io(struct work_struct *work)
 680 {
 681         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 682
 683         if (bio_data_dir(io->base_bio) == READ)
 684                 crypt_read_io(io);
 685         else
 686                 crypt_write_io(io);
 687 }
 688
 689 static void kcryptd_do_crypt(struct work_struct *work)
 690 {
 691         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 692
 693         if (bio_data_dir(io->base_bio) == READ)
 694                 crypt_read_io_process(io);
 695         else
 696                 crypt_write_io_process(io);
 697 }
 698
 699 /*
 700  * Decode key from its hex representation
 701  */
 702 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 703 {
 704         char buffer[3];
 705         char *endp;
 706         unsigned int i;
 707
 708         buffer[2] = '\0';
 709
 710         for (i = 0; i < size; i++) {
 711                 buffer[0] = *hex++;
 712                 buffer[1] = *hex++;
 713
 714                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 715
 716                 if (endp != &buffer[2])
 717                         return -EINVAL;
 718         }
 719
 720         if (*hex != '\0')
 721                 return -EINVAL;
 722
 723         return 0;
 724 }
 725
 726 /*
 727  * Encode key into its hex representation
 728  */
 729 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
 730 {
 731         unsigned int i;
 732
 733         for (i = 0; i < size; i++) {
 734                 sprintf(hex, "%02x", *key);
 735                 hex += 2;
 736                 key++;
 737         }
 738 }
 739
 740 static int crypt_set_key(struct crypt_config *cc, char *key)
 741 {
 742         unsigned key_size = strlen(key) >> 1;
 743
 744         if (cc->key_size && cc->key_size != key_size)
 745                 return -EINVAL;
 746
 747         cc->key_size = key_size; /* initial settings */
 748
 749         if ((!key_size && strcmp(key, "-")) ||
 750            (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
 751                 return -EINVAL;
 752
 753         set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 754
 755         return 0;
 756 }
 757
 758 static int crypt_wipe_key(struct crypt_config *cc)
 759 {
 760         clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 761         memset(&cc->key, 0, cc->key_size * sizeof(u8));
 762         return 0;
 763 }
 764
 765 /*
 766  * Construct an encryption mapping:
 767  * <cipher> <key> <iv_offset> <dev_path> <start>
 768  */
 769 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 770 {
 771         struct crypt_config *cc;
 772         struct crypto_blkcipher *tfm;
 773         char *tmp;
 774         char *cipher;
 775         char *chainmode;
 776         char *ivmode;
 777         char *ivopts;
 778         unsigned int key_size;
 779         unsigned long long tmpll;
 780
 781         if (argc != 5) {
 782                 ti->error = "Not enough arguments";
 783                 return -EINVAL;
 784         }
 785
 786         tmp = argv[0];
 787         cipher = strsep(&tmp, "-");
 788         chainmode = strsep(&tmp, "-");
 789         ivopts = strsep(&tmp, "-");
 790         ivmode = strsep(&ivopts, ":");
 791
 792         if (tmp)
 793                 DMWARN("Unexpected additional cipher options");
 794
 795         key_size = strlen(argv[1]) >> 1;
 796
 797         cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 798         if (cc == NULL) {
 799                 ti->error =
 800                         "Cannot allocate transparent encryption context";
 801                 return -ENOMEM;
 802         }
 803
 804         if (crypt_set_key(cc, argv[1])) {
 805                 ti->error = "Error decoding key";
 806                 goto bad_cipher;
 807         }
 808
 809         /* Compatiblity mode for old dm-crypt cipher strings */
 810         if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 811                 chainmode = "cbc";
 812                 ivmode = "plain";
 813         }
 814
 815         if (strcmp(chainmode, "ecb") && !ivmode) {
 816                 ti->error = "This chaining mode requires an IV mechanism";
 817                 goto bad_cipher;
 818         }
 819
 820         if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)",
 821                      chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) {
 822                 ti->error = "Chain mode + cipher name is too long";
 823                 goto bad_cipher;
 824         }
 825
 826         tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 827         if (IS_ERR(tfm)) {
 828                 ti->error = "Error allocating crypto tfm";
 829                 goto bad_cipher;
 830         }
 831
 832         strcpy(cc->cipher, cipher);
 833         strcpy(cc->chainmode, chainmode);
 834         cc->tfm = tfm;
 835
 836         /*
 837          * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
 838          * See comments at iv code
 839          */
 840
 841         if (ivmode == NULL)
 842                 cc->iv_gen_ops = NULL;
 843         else if (strcmp(ivmode, "plain") == 0)
 844                 cc->iv_gen_ops = &crypt_iv_plain_ops;
 845         else if (strcmp(ivmode, "essiv") == 0)
 846                 cc->iv_gen_ops = &crypt_iv_essiv_ops;
 847         else if (strcmp(ivmode, "benbi") == 0)
 848                 cc->iv_gen_ops = &crypt_iv_benbi_ops;
 849         else if (strcmp(ivmode, "null") == 0)
 850                 cc->iv_gen_ops = &crypt_iv_null_ops;
 851         else {
 852                 ti->error = "Invalid IV mode";
 853                 goto bad_ivmode;
 854         }
 855
 856         if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
 857             cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
 858                 goto bad_ivmode;
 859
 860         cc->iv_size = crypto_blkcipher_ivsize(tfm);
 861         if (cc->iv_size)
 862                 /* at least a 64 bit sector number should fit in our buffer */
 863                 cc->iv_size = max(cc->iv_size,
 864                                   (unsigned int)(sizeof(u64) / sizeof(u8)));
 865         else {
 866                 if (cc->iv_gen_ops) {
 867                         DMWARN("Selected cipher does not support IVs");
 868                         if (cc->iv_gen_ops->dtr)
 869                                 cc->iv_gen_ops->dtr(cc);
 870                         cc->iv_gen_ops = NULL;
 871                 }
 872         }
 873
 874         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
 875         if (!cc->io_pool) {
 876                 ti->error = "Cannot allocate crypt io mempool";
 877                 goto bad_slab_pool;
 878         }
 879
 880         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
 881         if (!cc->page_pool) {
 882                 ti->error = "Cannot allocate page mempool";
 883                 goto bad_page_pool;
 884         }
 885
 886         cc->bs = bioset_create(MIN_IOS, MIN_IOS);
 887         if (!cc->bs) {
 888                 ti->error = "Cannot allocate crypt bioset";
 889                 goto bad_bs;
 890         }
 891
 892         if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
 893                 ti->error = "Error setting key";
 894                 goto bad_device;
 895         }
 896
 897         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 898                 ti->error = "Invalid iv_offset sector";
 899                 goto bad_device;
 900         }
 901         cc->iv_offset = tmpll;
 902
 903         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
 904                 ti->error = "Invalid device sector";
 905                 goto bad_device;
 906         }
 907         cc->start = tmpll;
 908
 909         if (dm_get_device(ti, argv[3], cc->start, ti->len,
 910                           dm_table_get_mode(ti->table), &cc->dev)) {
 911                 ti->error = "Device lookup failed";
 912                 goto bad_device;
 913         }
 914
 915         if (ivmode && cc->iv_gen_ops) {
 916                 if (ivopts)
 917                         *(ivopts - 1) = ':';
 918                 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
 919                 if (!cc->iv_mode) {
 920                         ti->error = "Error kmallocing iv_mode string";
 921                         goto bad_ivmode_string;
 922                 }
 923                 strcpy(cc->iv_mode, ivmode);
 924         } else
 925                 cc->iv_mode = NULL;
 926
 927         cc->io_queue = create_singlethread_workqueue("kcryptd_io");
 928         if (!cc->io_queue) {
 929                 ti->error = "Couldn't create kcryptd io queue";
 930                 goto bad_io_queue;
 931         }
 932
 933         cc->crypt_queue = create_singlethread_workqueue("kcryptd");
 934         if (!cc->crypt_queue) {
 935                 ti->error = "Couldn't create kcryptd queue";
 936                 goto bad_crypt_queue;
 937         }
 938
 939         ti->private = cc;
 940         return 0;
 941
 942 bad_crypt_queue:
 943         destroy_workqueue(cc->io_queue);
 944 bad_io_queue:
 945         kfree(cc->iv_mode);
 946 bad_ivmode_string:
 947         dm_put_device(ti, cc->dev);
 948 bad_device:
 949         bioset_free(cc->bs);
 950 bad_bs:
 951         mempool_destroy(cc->page_pool);
 952 bad_page_pool:
 953         mempool_destroy(cc->io_pool);
 954 bad_slab_pool:
 955         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 956                 cc->iv_gen_ops->dtr(cc);
 957 bad_ivmode:
 958         crypto_free_blkcipher(tfm);
 959 bad_cipher:
 960         /* Must zero key material before freeing */
 961         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 962         kfree(cc);
 963         return -EINVAL;
 964 }
 965
 966 static void crypt_dtr(struct dm_target *ti)
 967 {
 968         struct crypt_config *cc = (struct crypt_config *) ti->private;
 969
 970         destroy_workqueue(cc->io_queue);
 971         destroy_workqueue(cc->crypt_queue);
 972
 973         bioset_free(cc->bs);
 974         mempool_destroy(cc->page_pool);
 975         mempool_destroy(cc->io_pool);
 976
 977         kfree(cc->iv_mode);
 978         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 979                 cc->iv_gen_ops->dtr(cc);
 980         crypto_free_blkcipher(cc->tfm);
 981         dm_put_device(ti, cc->dev);
 982
 983         /* Must zero key material before freeing */
 984         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 985         kfree(cc);
 986 }
 987
 988 static int crypt_map(struct dm_target *ti, struct bio *bio,
 989                      union map_info *map_context)
 990 {
 991         struct crypt_config *cc = ti->private;
 992         struct dm_crypt_io *io;
 993
 994         io = mempool_alloc(cc->io_pool, GFP_NOIO);
 995         io->target = ti;
 996         io->base_bio = bio;
 997         io->sector = bio->bi_sector - ti->begin;
 998         io->error = 0;
 999         atomic_set(&io->pending, 0);
1000
1001         if (bio_data_dir(io->base_bio) == READ)
1002                 kcryptd_queue_io(io);
1003         else
1004                 kcryptd_queue_crypt(io);
1005
1006         return DM_MAPIO_SUBMITTED;
1007 }
1008
1009 static int crypt_status(struct dm_target *ti, status_type_t type,
1010                         char *result, unsigned int maxlen)
1011 {
1012         struct crypt_config *cc = (struct crypt_config *) ti->private;
1013         unsigned int sz = 0;
1014
1015         switch (type) {
1016         case STATUSTYPE_INFO:
1017                 result[0] = '\0';
1018                 break;
1019
1020         case STATUSTYPE_TABLE:
1021                 if (cc->iv_mode)
1022                         DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
1023                                cc->iv_mode);
1024                 else
1025                         DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
1026
1027                 if (cc->key_size > 0) {
1028                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
1029                                 return -ENOMEM;
1030
1031                         crypt_encode_key(result + sz, cc->key, cc->key_size);
1032                         sz += cc->key_size << 1;
1033                 } else {
1034                         if (sz >= maxlen)
1035                                 return -ENOMEM;
1036                         result[sz++] = '-';
1037                 }
1038
1039                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
1040                                 cc->dev->name, (unsigned long long)cc->start);
1041                 break;
1042         }
1043         return 0;
1044 }
1045
1046 static void crypt_postsuspend(struct dm_target *ti)
1047 {
1048         struct crypt_config *cc = ti->private;
1049
1050         set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1051 }
1052
1053 static int crypt_preresume(struct dm_target *ti)
1054 {
1055         struct crypt_config *cc = ti->private;
1056
1057         if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
1058                 DMERR("aborting resume - crypt key is not set.");
1059                 return -EAGAIN;
1060         }
1061
1062         return 0;
1063 }
1064
1065 static void crypt_resume(struct dm_target *ti)
1066 {
1067         struct crypt_config *cc = ti->private;
1068
1069         clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1070 }
1071
1072 /* Message interface
1073  *      key set <key>
1074  *      key wipe
1075  */
1076 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1077 {
1078         struct crypt_config *cc = ti->private;
1079
1080         if (argc < 2)
1081                 goto error;
1082
1083         if (!strnicmp(argv[0], MESG_STR("key"))) {
1084                 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1085                         DMWARN("not suspended during key manipulation.");
1086                         return -EINVAL;
1087                 }
1088                 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1089                         return crypt_set_key(cc, argv[2]);
1090                 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1091                         return crypt_wipe_key(cc);
1092         }
1093
1094 error:
1095         DMWARN("unrecognised message received.");
1096         return -EINVAL;
1097 }
1098
1099 static struct target_type crypt_target = {
1100         .name   = "crypt",
1101         .version= {1, 5, 0},
1102         .module = THIS_MODULE,
1103         .ctr    = crypt_ctr,
1104         .dtr    = crypt_dtr,
1105         .map    = crypt_map,
1106         .status = crypt_status,
1107         .postsuspend = crypt_postsuspend,
1108         .preresume = crypt_preresume,
1109         .resume = crypt_resume,
1110         .message = crypt_message,
1111 };
1112
1113 static int __init dm_crypt_init(void)
1114 {
1115         int r;
1116
1117         _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
1118         if (!_crypt_io_pool)
1119                 return -ENOMEM;
1120
1121         r = dm_register_target(&crypt_target);
1122         if (r < 0) {
1123                 DMERR("register failed %d", r);
1124                 kmem_cache_destroy(_crypt_io_pool);
1125         }
1126
1127         return r;
1128 }
1129
1130 static void __exit dm_crypt_exit(void)
1131 {
1132         int r = dm_unregister_target(&crypt_target);
1133
1134         if (r < 0)
1135                 DMERR("unregister failed %d", r);
1136
1137         kmem_cache_destroy(_crypt_io_pool);
1138 }
1139
1140 module_init(dm_crypt_init);
1141 module_exit(dm_crypt_exit);
1142
1143 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1144 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1145 MODULE_LICENSE("GPL");