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 };
  40
  41 /*
  42  * context holding the current state of a multi-part conversion
  43  */
  44 struct convert_context {
  45         struct bio *bio_in;
  46         struct bio *bio_out;
  47         unsigned int offset_in;
  48         unsigned int offset_out;
  49         unsigned int idx_in;
  50         unsigned int idx_out;
  51         sector_t sector;
  52         int write;
  53 };
  54
  55 struct crypt_config;
  56
  57 struct crypt_iv_operations {
  58         int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
  59                    const char *opts);
  60         void (*dtr)(struct crypt_config *cc);
  61         const char *(*status)(struct crypt_config *cc);
  62         int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
  63 };
  64
  65 /*
  66  * Crypt: maps a linear range of a block device
  67  * and encrypts / decrypts at the same time.
  68  */
  69 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
  70 struct crypt_config {
  71         struct dm_dev *dev;
  72         sector_t start;
  73
  74         /*
  75          * pool for per bio private data and
  76          * for encryption buffer pages
  77          */
  78         mempool_t *io_pool;
  79         mempool_t *page_pool;
  80         struct bio_set *bs;
  81
  82         struct workqueue_struct *io_queue;
  83         struct workqueue_struct *crypt_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 necessary.
 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_init_one(&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 crypt_convert_init(struct crypt_config *cc,
 325                                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, sg_out;
 352
 353                 sg_init_table(&sg_in, 1);
 354                 sg_set_page(&sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT, bv_in->bv_offset + ctx->offset_in);
 355
 356                 sg_init_table(&sg_out, 1);
 357                 sg_set_page(&sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT, bv_out->bv_offset + ctx->offset_out);
 358
 359                 ctx->offset_in += sg_in.length;
 360                 if (ctx->offset_in >= bv_in->bv_len) {
 361                         ctx->offset_in = 0;
 362                         ctx->idx_in++;
 363                 }
 364
 365                 ctx->offset_out += sg_out.length;
 366                 if (ctx->offset_out >= bv_out->bv_len) {
 367                         ctx->offset_out = 0;
 368                         ctx->idx_out++;
 369                 }
 370
 371                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 372                                               ctx->write, ctx->sector);
 373                 if (r < 0)
 374                         break;
 375
 376                 ctx->sector++;
 377         }
 378
 379         return r;
 380 }
 381
 382 static void dm_crypt_bio_destructor(struct bio *bio)
 383 {
 384         struct dm_crypt_io *io = bio->bi_private;
 385         struct crypt_config *cc = io->target->private;
 386
 387         bio_free(bio, cc->bs);
 388 }
 389
 390 /*
 391  * Generate a new unfragmented bio with the given size
 392  * This should never violate the device limitations
 393  * May return a smaller bio when running out of pages
 394  */
 395 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
 396 {
 397         struct crypt_config *cc = io->target->private;
 398         struct bio *clone;
 399         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 400         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 401         unsigned i, len;
 402         struct page *page;
 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                 page = mempool_alloc(cc->page_pool, gfp_mask);
 412                 if (!page)
 413                         break;
 414
 415                 /*
 416                  * if additional pages cannot be allocated without waiting,
 417                  * return a partially allocated bio, the caller will then try
 418                  * to allocate additional bios while submitting this partial bio
 419                  */
 420                 if (i == (MIN_BIO_PAGES - 1))
 421                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 422
 423                 len = (size > PAGE_SIZE) ? PAGE_SIZE : size;
 424
 425                 if (!bio_add_page(clone, page, len, 0)) {
 426                         mempool_free(page, cc->page_pool);
 427                         break;
 428                 }
 429
 430                 size -= len;
 431         }
 432
 433         if (!clone->bi_size) {
 434                 bio_put(clone);
 435                 return NULL;
 436         }
 437
 438         return clone;
 439 }
 440
 441 static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
 442 {
 443         unsigned int i;
 444         struct bio_vec *bv;
 445
 446         for (i = 0; i < clone->bi_vcnt; i++) {
 447                 bv = bio_iovec_idx(clone, i);
 448                 BUG_ON(!bv->bv_page);
 449                 mempool_free(bv->bv_page, cc->page_pool);
 450                 bv->bv_page = NULL;
 451         }
 452 }
 453
 454 /*
 455  * One of the bios was finished. Check for completion of
 456  * the whole request and correctly clean up the buffer.
 457  */
 458 static void crypt_dec_pending(struct dm_crypt_io *io, int error)
 459 {
 460         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 461
 462         if (error < 0)
 463                 io->error = error;
 464
 465         if (!atomic_dec_and_test(&io->pending))
 466                 return;
 467
 468         bio_endio(io->base_bio, io->error);
 469
 470         mempool_free(io, cc->io_pool);
 471 }
 472
 473 /*
 474  * kcryptd/kcryptd_io:
 475  *
 476  * Needed because it would be very unwise to do decryption in an
 477  * interrupt context.
 478  *
 479  * kcryptd performs the actual encryption or decryption.
 480  *
 481  * kcryptd_io performs the IO submission.
 482  *
 483  * They must be separated as otherwise the final stages could be
 484  * starved by new requests which can block in the first stages due
 485  * to memory allocation.
 486  */
 487 static void kcryptd_do_work(struct work_struct *work);
 488 static void kcryptd_do_crypt(struct work_struct *work);
 489
 490 static void kcryptd_queue_io(struct dm_crypt_io *io)
 491 {
 492         struct crypt_config *cc = io->target->private;
 493
 494         INIT_WORK(&io->work, kcryptd_do_work);
 495         queue_work(cc->io_queue, &io->work);
 496 }
 497
 498 static void kcryptd_queue_crypt(struct dm_crypt_io *io)
 499 {
 500         struct crypt_config *cc = io->target->private;
 501
 502         INIT_WORK(&io->work, kcryptd_do_crypt);
 503         queue_work(cc->crypt_queue, &io->work);
 504 }
 505
 506 static void crypt_endio(struct bio *clone, int error)
 507 {
 508         struct dm_crypt_io *io = clone->bi_private;
 509         struct crypt_config *cc = io->target->private;
 510         unsigned read_io = bio_data_dir(clone) == READ;
 511
 512         if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
 513                 error = -EIO;
 514
 515         /*
 516          * free the processed pages
 517          */
 518         if (!read_io) {
 519                 crypt_free_buffer_pages(cc, clone);
 520                 goto out;
 521         }
 522
 523         if (unlikely(error))
 524                 goto out;
 525
 526         bio_put(clone);
 527         kcryptd_queue_crypt(io);
 528         return;
 529
 530 out:
 531         bio_put(clone);
 532         crypt_dec_pending(io, error);
 533 }
 534
 535 static void clone_init(struct dm_crypt_io *io, struct bio *clone)
 536 {
 537         struct crypt_config *cc = io->target->private;
 538
 539         clone->bi_private = io;
 540         clone->bi_end_io  = crypt_endio;
 541         clone->bi_bdev    = cc->dev->bdev;
 542         clone->bi_rw      = io->base_bio->bi_rw;
 543         clone->bi_destructor = dm_crypt_bio_destructor;
 544 }
 545
 546 static void process_read(struct dm_crypt_io *io)
 547 {
 548         struct crypt_config *cc = io->target->private;
 549         struct bio *base_bio = io->base_bio;
 550         struct bio *clone;
 551         sector_t sector = base_bio->bi_sector - io->target->begin;
 552
 553         atomic_inc(&io->pending);
 554
 555         /*
 556          * The block layer might modify the bvec array, so always
 557          * copy the required bvecs because we need the original
 558          * one in order to decrypt the whole bio data *afterwards*.
 559          */
 560         clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
 561         if (unlikely(!clone)) {
 562                 crypt_dec_pending(io, -ENOMEM);
 563                 return;
 564         }
 565
 566         clone_init(io, clone);
 567         clone->bi_idx = 0;
 568         clone->bi_vcnt = bio_segments(base_bio);
 569         clone->bi_size = base_bio->bi_size;
 570         clone->bi_sector = cc->start + sector;
 571         memcpy(clone->bi_io_vec, bio_iovec(base_bio),
 572                sizeof(struct bio_vec) * clone->bi_vcnt);
 573
 574         generic_make_request(clone);
 575 }
 576
 577 static void process_write(struct dm_crypt_io *io)
 578 {
 579         struct crypt_config *cc = io->target->private;
 580         struct bio *base_bio = io->base_bio;
 581         struct bio *clone;
 582         struct convert_context ctx;
 583         unsigned remaining = base_bio->bi_size;
 584         sector_t sector = base_bio->bi_sector - io->target->begin;
 585
 586         atomic_inc(&io->pending);
 587
 588         crypt_convert_init(cc, &ctx, NULL, base_bio, sector, 1);
 589
 590         /*
 591          * The allocated buffers can be smaller than the whole bio,
 592          * so repeat the whole process until all the data can be handled.
 593          */
 594         while (remaining) {
 595                 clone = crypt_alloc_buffer(io, remaining);
 596                 if (unlikely(!clone)) {
 597                         crypt_dec_pending(io, -ENOMEM);
 598                         return;
 599                 }
 600
 601                 ctx.bio_out = clone;
 602                 ctx.idx_out = 0;
 603
 604                 if (unlikely(crypt_convert(cc, &ctx) < 0)) {
 605                         crypt_free_buffer_pages(cc, clone);
 606                         bio_put(clone);
 607                         crypt_dec_pending(io, -EIO);
 608                         return;
 609                 }
 610
 611                 /* crypt_convert should have filled the clone bio */
 612                 BUG_ON(ctx.idx_out < clone->bi_vcnt);
 613
 614                 clone->bi_sector = cc->start + sector;
 615                 remaining -= clone->bi_size;
 616                 sector += bio_sectors(clone);
 617
 618                 /* Grab another reference to the io struct
 619                  * before we kick off the request */
 620                 if (remaining)
 621                         atomic_inc(&io->pending);
 622
 623                 generic_make_request(clone);
 624
 625                 /* Do not reference clone after this - it
 626                  * may be gone already. */
 627
 628                 /* out of memory -> run queues */
 629                 if (remaining)
 630                         congestion_wait(WRITE, HZ/100);
 631         }
 632 }
 633
 634 static void process_read_endio(struct dm_crypt_io *io)
 635 {
 636         struct crypt_config *cc = io->target->private;
 637         struct convert_context ctx;
 638
 639         crypt_convert_init(cc, &ctx, io->base_bio, io->base_bio,
 640                            io->base_bio->bi_sector - io->target->begin, 0);
 641
 642         crypt_dec_pending(io, crypt_convert(cc, &ctx));
 643 }
 644
 645 static void kcryptd_do_work(struct work_struct *work)
 646 {
 647         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 648
 649         if (bio_data_dir(io->base_bio) == READ)
 650                 process_read(io);
 651 }
 652
 653 static void kcryptd_do_crypt(struct work_struct *work)
 654 {
 655         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 656
 657         if (bio_data_dir(io->base_bio) == READ)
 658                 process_read_endio(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 bad_cipher;
 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 bad_cipher;
 782         }
 783
 784         if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)",
 785                      chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) {
 786                 ti->error = "Chain mode + cipher name is too long";
 787                 goto bad_cipher;
 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 bad_cipher;
 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 bad_ivmode;
 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 bad_ivmode;
 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 bad_slab_pool;
 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 bad_page_pool;
 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 bad_device;
 859         }
 860
 861         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 862                 ti->error = "Invalid iv_offset sector";
 863                 goto bad_device;
 864         }
 865         cc->iv_offset = tmpll;
 866
 867         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
 868                 ti->error = "Invalid device sector";
 869                 goto bad_device;
 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 bad_device;
 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 bad_ivmode_string;
 886                 }
 887                 strcpy(cc->iv_mode, ivmode);
 888         } else
 889                 cc->iv_mode = NULL;
 890
 891         cc->io_queue = create_singlethread_workqueue("kcryptd_io");
 892         if (!cc->io_queue) {
 893                 ti->error = "Couldn't create kcryptd io queue";
 894                 goto bad_io_queue;
 895         }
 896
 897         cc->crypt_queue = create_singlethread_workqueue("kcryptd");
 898         if (!cc->crypt_queue) {
 899                 ti->error = "Couldn't create kcryptd queue";
 900                 goto bad_crypt_queue;
 901         }
 902
 903         ti->private = cc;
 904         return 0;
 905
 906 bad_crypt_queue:
 907         destroy_workqueue(cc->io_queue);
 908 bad_io_queue:
 909         kfree(cc->iv_mode);
 910 bad_ivmode_string:
 911         dm_put_device(ti, cc->dev);
 912 bad_device:
 913         bioset_free(cc->bs);
 914 bad_bs:
 915         mempool_destroy(cc->page_pool);
 916 bad_page_pool:
 917         mempool_destroy(cc->io_pool);
 918 bad_slab_pool:
 919         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 920                 cc->iv_gen_ops->dtr(cc);
 921 bad_ivmode:
 922         crypto_free_blkcipher(tfm);
 923 bad_cipher:
 924         /* Must zero key material before freeing */
 925         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 926         kfree(cc);
 927         return -EINVAL;
 928 }
 929
 930 static void crypt_dtr(struct dm_target *ti)
 931 {
 932         struct crypt_config *cc = (struct crypt_config *) ti->private;
 933
 934         destroy_workqueue(cc->io_queue);
 935         destroy_workqueue(cc->crypt_queue);
 936
 937         bioset_free(cc->bs);
 938         mempool_destroy(cc->page_pool);
 939         mempool_destroy(cc->io_pool);
 940
 941         kfree(cc->iv_mode);
 942         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 943                 cc->iv_gen_ops->dtr(cc);
 944         crypto_free_blkcipher(cc->tfm);
 945         dm_put_device(ti, cc->dev);
 946
 947         /* Must zero key material before freeing */
 948         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 949         kfree(cc);
 950 }
 951
 952 static int crypt_map(struct dm_target *ti, struct bio *bio,
 953                      union map_info *map_context)
 954 {
 955         struct crypt_config *cc = ti->private;
 956         struct dm_crypt_io *io;
 957
 958         io = mempool_alloc(cc->io_pool, GFP_NOIO);
 959         io->target = ti;
 960         io->base_bio = bio;
 961         io->error = 0;
 962         atomic_set(&io->pending, 0);
 963
 964         if (bio_data_dir(io->base_bio) == READ)
 965                 kcryptd_queue_io(io);
 966         else
 967                 kcryptd_queue_crypt(io);
 968
 969         return DM_MAPIO_SUBMITTED;
 970 }
 971
 972 static int crypt_status(struct dm_target *ti, status_type_t type,
 973                         char *result, unsigned int maxlen)
 974 {
 975         struct crypt_config *cc = (struct crypt_config *) ti->private;
 976         unsigned int sz = 0;
 977
 978         switch (type) {
 979         case STATUSTYPE_INFO:
 980                 result[0] = '\0';
 981                 break;
 982
 983         case STATUSTYPE_TABLE:
 984                 if (cc->iv_mode)
 985                         DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
 986                                cc->iv_mode);
 987                 else
 988                         DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
 989
 990                 if (cc->key_size > 0) {
 991                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
 992                                 return -ENOMEM;
 993
 994                         crypt_encode_key(result + sz, cc->key, cc->key_size);
 995                         sz += cc->key_size << 1;
 996                 } else {
 997                         if (sz >= maxlen)
 998                                 return -ENOMEM;
 999                         result[sz++] = '-';
1000                 }
1001
1002                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
1003                                 cc->dev->name, (unsigned long long)cc->start);
1004                 break;
1005         }
1006         return 0;
1007 }
1008
1009 static void crypt_postsuspend(struct dm_target *ti)
1010 {
1011         struct crypt_config *cc = ti->private;
1012
1013         set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1014 }
1015
1016 static int crypt_preresume(struct dm_target *ti)
1017 {
1018         struct crypt_config *cc = ti->private;
1019
1020         if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
1021                 DMERR("aborting resume - crypt key is not set.");
1022                 return -EAGAIN;
1023         }
1024
1025         return 0;
1026 }
1027
1028 static void crypt_resume(struct dm_target *ti)
1029 {
1030         struct crypt_config *cc = ti->private;
1031
1032         clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1033 }
1034
1035 /* Message interface
1036  *      key set <key>
1037  *      key wipe
1038  */
1039 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1040 {
1041         struct crypt_config *cc = ti->private;
1042
1043         if (argc < 2)
1044                 goto error;
1045
1046         if (!strnicmp(argv[0], MESG_STR("key"))) {
1047                 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1048                         DMWARN("not suspended during key manipulation.");
1049                         return -EINVAL;
1050                 }
1051                 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1052                         return crypt_set_key(cc, argv[2]);
1053                 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1054                         return crypt_wipe_key(cc);
1055         }
1056
1057 error:
1058         DMWARN("unrecognised message received.");
1059         return -EINVAL;
1060 }
1061
1062 static struct target_type crypt_target = {
1063         .name   = "crypt",
1064         .version= {1, 5, 0},
1065         .module = THIS_MODULE,
1066         .ctr    = crypt_ctr,
1067         .dtr    = crypt_dtr,
1068         .map    = crypt_map,
1069         .status = crypt_status,
1070         .postsuspend = crypt_postsuspend,
1071         .preresume = crypt_preresume,
1072         .resume = crypt_resume,
1073         .message = crypt_message,
1074 };
1075
1076 static int __init dm_crypt_init(void)
1077 {
1078         int r;
1079
1080         _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
1081         if (!_crypt_io_pool)
1082                 return -ENOMEM;
1083
1084         r = dm_register_target(&crypt_target);
1085         if (r < 0) {
1086                 DMERR("register failed %d", r);
1087                 kmem_cache_destroy(_crypt_io_pool);
1088         }
1089
1090         return r;
1091 }
1092
1093 static void __exit dm_crypt_exit(void)
1094 {
1095         int r = dm_unregister_target(&crypt_target);
1096
1097         if (r < 0)
1098                 DMERR("unregister failed %d", r);
1099
1100         kmem_cache_destroy(_crypt_io_pool);
1101 }
1102
1103 module_init(dm_crypt_init);
1104 module_exit(dm_crypt_exit);
1105
1106 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1107 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1108 MODULE_LICENSE("GPL");