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  * 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         int write;
  42 };
  43
  44 /*
  45  * per bio private data
  46  */
  47 struct dm_crypt_io {
  48         struct dm_target *target;
  49         struct bio *base_bio;
  50         struct work_struct work;
  51
  52         struct convert_context ctx;
  53
  54         atomic_t pending;
  55         int error;
  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 int
 296 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
 297                           struct scatterlist *in, unsigned int length,
 298                           int write, sector_t sector)
 299 {
 300         u8 iv[cc->iv_size] __attribute__ ((aligned(__alignof__(u64))));
 301         struct blkcipher_desc desc = {
 302                 .tfm = cc->tfm,
 303                 .info = iv,
 304                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP,
 305         };
 306         int r;
 307
 308         if (cc->iv_gen_ops) {
 309                 r = cc->iv_gen_ops->generator(cc, iv, sector);
 310                 if (r < 0)
 311                         return r;
 312
 313                 if (write)
 314                         r = crypto_blkcipher_encrypt_iv(&desc, out, in, length);
 315                 else
 316                         r = crypto_blkcipher_decrypt_iv(&desc, out, in, length);
 317         } else {
 318                 if (write)
 319                         r = crypto_blkcipher_encrypt(&desc, out, in, length);
 320                 else
 321                         r = crypto_blkcipher_decrypt(&desc, out, in, length);
 322         }
 323
 324         return r;
 325 }
 326
 327 static void crypt_convert_init(struct crypt_config *cc,
 328                                struct convert_context *ctx,
 329                                struct bio *bio_out, struct bio *bio_in,
 330                                sector_t sector, int write)
 331 {
 332         ctx->bio_in = bio_in;
 333         ctx->bio_out = bio_out;
 334         ctx->offset_in = 0;
 335         ctx->offset_out = 0;
 336         ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
 337         ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
 338         ctx->sector = sector + cc->iv_offset;
 339         ctx->write = write;
 340 }
 341
 342 /*
 343  * Encrypt / decrypt data from one bio to another one (can be the same one)
 344  */
 345 static int crypt_convert(struct crypt_config *cc,
 346                          struct convert_context *ctx)
 347 {
 348         int r = 0;
 349
 350         while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
 351               ctx->idx_out < ctx->bio_out->bi_vcnt) {
 352                 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
 353                 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
 354                 struct scatterlist sg_in, sg_out;
 355
 356                 sg_init_table(&sg_in, 1);
 357                 sg_set_page(&sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT, bv_in->bv_offset + ctx->offset_in);
 358
 359                 sg_init_table(&sg_out, 1);
 360                 sg_set_page(&sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT, bv_out->bv_offset + ctx->offset_out);
 361
 362                 ctx->offset_in += sg_in.length;
 363                 if (ctx->offset_in >= bv_in->bv_len) {
 364                         ctx->offset_in = 0;
 365                         ctx->idx_in++;
 366                 }
 367
 368                 ctx->offset_out += sg_out.length;
 369                 if (ctx->offset_out >= bv_out->bv_len) {
 370                         ctx->offset_out = 0;
 371                         ctx->idx_out++;
 372                 }
 373
 374                 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
 375                                               ctx->write, ctx->sector);
 376                 if (r < 0)
 377                         break;
 378
 379                 ctx->sector++;
 380         }
 381
 382         return r;
 383 }
 384
 385 static void dm_crypt_bio_destructor(struct bio *bio)
 386 {
 387         struct dm_crypt_io *io = bio->bi_private;
 388         struct crypt_config *cc = io->target->private;
 389
 390         bio_free(bio, cc->bs);
 391 }
 392
 393 /*
 394  * Generate a new unfragmented bio with the given size
 395  * This should never violate the device limitations
 396  * May return a smaller bio when running out of pages
 397  */
 398 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
 399 {
 400         struct crypt_config *cc = io->target->private;
 401         struct bio *clone;
 402         unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 403         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
 404         unsigned i, len;
 405         struct page *page;
 406
 407         clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
 408         if (!clone)
 409                 return NULL;
 410
 411         clone_init(io, clone);
 412
 413         for (i = 0; i < nr_iovecs; i++) {
 414                 page = mempool_alloc(cc->page_pool, gfp_mask);
 415                 if (!page)
 416                         break;
 417
 418                 /*
 419                  * if additional pages cannot be allocated without waiting,
 420                  * return a partially allocated bio, the caller will then try
 421                  * to allocate additional bios while submitting this partial bio
 422                  */
 423                 if (i == (MIN_BIO_PAGES - 1))
 424                         gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
 425
 426                 len = (size > PAGE_SIZE) ? PAGE_SIZE : size;
 427
 428                 if (!bio_add_page(clone, page, len, 0)) {
 429                         mempool_free(page, cc->page_pool);
 430                         break;
 431                 }
 432
 433                 size -= 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, struct bio *clone)
 445 {
 446         unsigned int i;
 447         struct bio_vec *bv;
 448
 449         for (i = 0; i < clone->bi_vcnt; i++) {
 450                 bv = bio_iovec_idx(clone, i);
 451                 BUG_ON(!bv->bv_page);
 452                 mempool_free(bv->bv_page, cc->page_pool);
 453                 bv->bv_page = NULL;
 454         }
 455 }
 456
 457 /*
 458  * One of the bios was finished. Check for completion of
 459  * the whole request and correctly clean up the buffer.
 460  */
 461 static void crypt_dec_pending(struct dm_crypt_io *io, int error)
 462 {
 463         struct crypt_config *cc = (struct crypt_config *) io->target->private;
 464
 465         if (error < 0)
 466                 io->error = error;
 467
 468         if (!atomic_dec_and_test(&io->pending))
 469                 return;
 470
 471         bio_endio(io->base_bio, io->error);
 472
 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_work(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_work);
 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 read_io = bio_data_dir(clone) == READ;
 514
 515         if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
 516                 error = -EIO;
 517
 518         /*
 519          * free the processed pages
 520          */
 521         if (!read_io) {
 522                 crypt_free_buffer_pages(cc, clone);
 523                 goto out;
 524         }
 525
 526         if (unlikely(error))
 527                 goto out;
 528
 529         bio_put(clone);
 530         kcryptd_queue_crypt(io);
 531         return;
 532
 533 out:
 534         bio_put(clone);
 535         crypt_dec_pending(io, error);
 536 }
 537
 538 static void clone_init(struct dm_crypt_io *io, struct bio *clone)
 539 {
 540         struct crypt_config *cc = io->target->private;
 541
 542         clone->bi_private = io;
 543         clone->bi_end_io  = crypt_endio;
 544         clone->bi_bdev    = cc->dev->bdev;
 545         clone->bi_rw      = io->base_bio->bi_rw;
 546         clone->bi_destructor = dm_crypt_bio_destructor;
 547 }
 548
 549 static void process_read(struct dm_crypt_io *io)
 550 {
 551         struct crypt_config *cc = io->target->private;
 552         struct bio *base_bio = io->base_bio;
 553         struct bio *clone;
 554         sector_t sector = base_bio->bi_sector - io->target->begin;
 555
 556         atomic_inc(&io->pending);
 557
 558         /*
 559          * The block layer might modify the bvec array, so always
 560          * copy the required bvecs because we need the original
 561          * one in order to decrypt the whole bio data *afterwards*.
 562          */
 563         clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
 564         if (unlikely(!clone)) {
 565                 crypt_dec_pending(io, -ENOMEM);
 566                 return;
 567         }
 568
 569         clone_init(io, clone);
 570         clone->bi_idx = 0;
 571         clone->bi_vcnt = bio_segments(base_bio);
 572         clone->bi_size = base_bio->bi_size;
 573         clone->bi_sector = cc->start + sector;
 574         memcpy(clone->bi_io_vec, bio_iovec(base_bio),
 575                sizeof(struct bio_vec) * clone->bi_vcnt);
 576
 577         generic_make_request(clone);
 578 }
 579
 580 static void process_write(struct dm_crypt_io *io)
 581 {
 582         struct crypt_config *cc = io->target->private;
 583         struct bio *base_bio = io->base_bio;
 584         struct bio *clone;
 585         unsigned remaining = base_bio->bi_size;
 586         sector_t sector = base_bio->bi_sector - io->target->begin;
 587
 588         atomic_inc(&io->pending);
 589
 590         crypt_convert_init(cc, &io->ctx, NULL, base_bio, sector, 1);
 591
 592         /*
 593          * The allocated buffers can be smaller than the whole bio,
 594          * so repeat the whole process until all the data can be handled.
 595          */
 596         while (remaining) {
 597                 clone = crypt_alloc_buffer(io, remaining);
 598                 if (unlikely(!clone)) {
 599                         crypt_dec_pending(io, -ENOMEM);
 600                         return;
 601                 }
 602
 603                 io->ctx.bio_out = clone;
 604                 io->ctx.idx_out = 0;
 605
 606                 if (unlikely(crypt_convert(cc, &io->ctx) < 0)) {
 607                         crypt_free_buffer_pages(cc, clone);
 608                         bio_put(clone);
 609                         crypt_dec_pending(io, -EIO);
 610                         return;
 611                 }
 612
 613                 /* crypt_convert should have filled the clone bio */
 614                 BUG_ON(io->ctx.idx_out < clone->bi_vcnt);
 615
 616                 clone->bi_sector = cc->start + sector;
 617                 remaining -= clone->bi_size;
 618                 sector += bio_sectors(clone);
 619
 620                 /* Grab another reference to the io struct
 621                  * before we kick off the request */
 622                 if (remaining)
 623                         atomic_inc(&io->pending);
 624
 625                 generic_make_request(clone);
 626
 627                 /* Do not reference clone after this - it
 628                  * may be gone already. */
 629
 630                 /* out of memory -> run queues */
 631                 if (remaining)
 632                         congestion_wait(WRITE, HZ/100);
 633         }
 634 }
 635
 636 static void process_read_endio(struct dm_crypt_io *io)
 637 {
 638         struct crypt_config *cc = io->target->private;
 639
 640         crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,
 641                            io->base_bio->bi_sector - io->target->begin, 0);
 642
 643         crypt_dec_pending(io, crypt_convert(cc, &io->ctx));
 644 }
 645
 646 static void kcryptd_do_work(struct work_struct *work)
 647 {
 648         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 649
 650         if (bio_data_dir(io->base_bio) == READ)
 651                 process_read(io);
 652 }
 653
 654 static void kcryptd_do_crypt(struct work_struct *work)
 655 {
 656         struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
 657
 658         if (bio_data_dir(io->base_bio) == READ)
 659                 process_read_endio(io);
 660         else
 661                 process_write(io);
 662 }
 663
 664 /*
 665  * Decode key from its hex representation
 666  */
 667 static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 668 {
 669         char buffer[3];
 670         char *endp;
 671         unsigned int i;
 672
 673         buffer[2] = '\0';
 674
 675         for (i = 0; i < size; i++) {
 676                 buffer[0] = *hex++;
 677                 buffer[1] = *hex++;
 678
 679                 key[i] = (u8)simple_strtoul(buffer, &endp, 16);
 680
 681                 if (endp != &buffer[2])
 682                         return -EINVAL;
 683         }
 684
 685         if (*hex != '\0')
 686                 return -EINVAL;
 687
 688         return 0;
 689 }
 690
 691 /*
 692  * Encode key into its hex representation
 693  */
 694 static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
 695 {
 696         unsigned int i;
 697
 698         for (i = 0; i < size; i++) {
 699                 sprintf(hex, "%02x", *key);
 700                 hex += 2;
 701                 key++;
 702         }
 703 }
 704
 705 static int crypt_set_key(struct crypt_config *cc, char *key)
 706 {
 707         unsigned key_size = strlen(key) >> 1;
 708
 709         if (cc->key_size && cc->key_size != key_size)
 710                 return -EINVAL;
 711
 712         cc->key_size = key_size; /* initial settings */
 713
 714         if ((!key_size && strcmp(key, "-")) ||
 715            (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
 716                 return -EINVAL;
 717
 718         set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 719
 720         return 0;
 721 }
 722
 723 static int crypt_wipe_key(struct crypt_config *cc)
 724 {
 725         clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 726         memset(&cc->key, 0, cc->key_size * sizeof(u8));
 727         return 0;
 728 }
 729
 730 /*
 731  * Construct an encryption mapping:
 732  * <cipher> <key> <iv_offset> <dev_path> <start>
 733  */
 734 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 735 {
 736         struct crypt_config *cc;
 737         struct crypto_blkcipher *tfm;
 738         char *tmp;
 739         char *cipher;
 740         char *chainmode;
 741         char *ivmode;
 742         char *ivopts;
 743         unsigned int key_size;
 744         unsigned long long tmpll;
 745
 746         if (argc != 5) {
 747                 ti->error = "Not enough arguments";
 748                 return -EINVAL;
 749         }
 750
 751         tmp = argv[0];
 752         cipher = strsep(&tmp, "-");
 753         chainmode = strsep(&tmp, "-");
 754         ivopts = strsep(&tmp, "-");
 755         ivmode = strsep(&ivopts, ":");
 756
 757         if (tmp)
 758                 DMWARN("Unexpected additional cipher options");
 759
 760         key_size = strlen(argv[1]) >> 1;
 761
 762         cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
 763         if (cc == NULL) {
 764                 ti->error =
 765                         "Cannot allocate transparent encryption context";
 766                 return -ENOMEM;
 767         }
 768
 769         if (crypt_set_key(cc, argv[1])) {
 770                 ti->error = "Error decoding key";
 771                 goto bad_cipher;
 772         }
 773
 774         /* Compatiblity mode for old dm-crypt cipher strings */
 775         if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
 776                 chainmode = "cbc";
 777                 ivmode = "plain";
 778         }
 779
 780         if (strcmp(chainmode, "ecb") && !ivmode) {
 781                 ti->error = "This chaining mode requires an IV mechanism";
 782                 goto bad_cipher;
 783         }
 784
 785         if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)",
 786                      chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) {
 787                 ti->error = "Chain mode + cipher name is too long";
 788                 goto bad_cipher;
 789         }
 790
 791         tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
 792         if (IS_ERR(tfm)) {
 793                 ti->error = "Error allocating crypto tfm";
 794                 goto bad_cipher;
 795         }
 796
 797         strcpy(cc->cipher, cipher);
 798         strcpy(cc->chainmode, chainmode);
 799         cc->tfm = tfm;
 800
 801         /*
 802          * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
 803          * See comments at iv code
 804          */
 805
 806         if (ivmode == NULL)
 807                 cc->iv_gen_ops = NULL;
 808         else if (strcmp(ivmode, "plain") == 0)
 809                 cc->iv_gen_ops = &crypt_iv_plain_ops;
 810         else if (strcmp(ivmode, "essiv") == 0)
 811                 cc->iv_gen_ops = &crypt_iv_essiv_ops;
 812         else if (strcmp(ivmode, "benbi") == 0)
 813                 cc->iv_gen_ops = &crypt_iv_benbi_ops;
 814         else if (strcmp(ivmode, "null") == 0)
 815                 cc->iv_gen_ops = &crypt_iv_null_ops;
 816         else {
 817                 ti->error = "Invalid IV mode";
 818                 goto bad_ivmode;
 819         }
 820
 821         if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
 822             cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
 823                 goto bad_ivmode;
 824
 825         cc->iv_size = crypto_blkcipher_ivsize(tfm);
 826         if (cc->iv_size)
 827                 /* at least a 64 bit sector number should fit in our buffer */
 828                 cc->iv_size = max(cc->iv_size,
 829                                   (unsigned int)(sizeof(u64) / sizeof(u8)));
 830         else {
 831                 if (cc->iv_gen_ops) {
 832                         DMWARN("Selected cipher does not support IVs");
 833                         if (cc->iv_gen_ops->dtr)
 834                                 cc->iv_gen_ops->dtr(cc);
 835                         cc->iv_gen_ops = NULL;
 836                 }
 837         }
 838
 839         cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
 840         if (!cc->io_pool) {
 841                 ti->error = "Cannot allocate crypt io mempool";
 842                 goto bad_slab_pool;
 843         }
 844
 845         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
 846         if (!cc->page_pool) {
 847                 ti->error = "Cannot allocate page mempool";
 848                 goto bad_page_pool;
 849         }
 850
 851         cc->bs = bioset_create(MIN_IOS, MIN_IOS);
 852         if (!cc->bs) {
 853                 ti->error = "Cannot allocate crypt bioset";
 854                 goto bad_bs;
 855         }
 856
 857         if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
 858                 ti->error = "Error setting key";
 859                 goto bad_device;
 860         }
 861
 862         if (sscanf(argv[2], "%llu", &tmpll) != 1) {
 863                 ti->error = "Invalid iv_offset sector";
 864                 goto bad_device;
 865         }
 866         cc->iv_offset = tmpll;
 867
 868         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
 869                 ti->error = "Invalid device sector";
 870                 goto bad_device;
 871         }
 872         cc->start = tmpll;
 873
 874         if (dm_get_device(ti, argv[3], cc->start, ti->len,
 875                           dm_table_get_mode(ti->table), &cc->dev)) {
 876                 ti->error = "Device lookup failed";
 877                 goto bad_device;
 878         }
 879
 880         if (ivmode && cc->iv_gen_ops) {
 881                 if (ivopts)
 882                         *(ivopts - 1) = ':';
 883                 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
 884                 if (!cc->iv_mode) {
 885                         ti->error = "Error kmallocing iv_mode string";
 886                         goto bad_ivmode_string;
 887                 }
 888                 strcpy(cc->iv_mode, ivmode);
 889         } else
 890                 cc->iv_mode = NULL;
 891
 892         cc->io_queue = create_singlethread_workqueue("kcryptd_io");
 893         if (!cc->io_queue) {
 894                 ti->error = "Couldn't create kcryptd io queue";
 895                 goto bad_io_queue;
 896         }
 897
 898         cc->crypt_queue = create_singlethread_workqueue("kcryptd");
 899         if (!cc->crypt_queue) {
 900                 ti->error = "Couldn't create kcryptd queue";
 901                 goto bad_crypt_queue;
 902         }
 903
 904         ti->private = cc;
 905         return 0;
 906
 907 bad_crypt_queue:
 908         destroy_workqueue(cc->io_queue);
 909 bad_io_queue:
 910         kfree(cc->iv_mode);
 911 bad_ivmode_string:
 912         dm_put_device(ti, cc->dev);
 913 bad_device:
 914         bioset_free(cc->bs);
 915 bad_bs:
 916         mempool_destroy(cc->page_pool);
 917 bad_page_pool:
 918         mempool_destroy(cc->io_pool);
 919 bad_slab_pool:
 920         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 921                 cc->iv_gen_ops->dtr(cc);
 922 bad_ivmode:
 923         crypto_free_blkcipher(tfm);
 924 bad_cipher:
 925         /* Must zero key material before freeing */
 926         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 927         kfree(cc);
 928         return -EINVAL;
 929 }
 930
 931 static void crypt_dtr(struct dm_target *ti)
 932 {
 933         struct crypt_config *cc = (struct crypt_config *) ti->private;
 934
 935         destroy_workqueue(cc->io_queue);
 936         destroy_workqueue(cc->crypt_queue);
 937
 938         bioset_free(cc->bs);
 939         mempool_destroy(cc->page_pool);
 940         mempool_destroy(cc->io_pool);
 941
 942         kfree(cc->iv_mode);
 943         if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
 944                 cc->iv_gen_ops->dtr(cc);
 945         crypto_free_blkcipher(cc->tfm);
 946         dm_put_device(ti, cc->dev);
 947
 948         /* Must zero key material before freeing */
 949         memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
 950         kfree(cc);
 951 }
 952
 953 static int crypt_map(struct dm_target *ti, struct bio *bio,
 954                      union map_info *map_context)
 955 {
 956         struct crypt_config *cc = ti->private;
 957         struct dm_crypt_io *io;
 958
 959         io = mempool_alloc(cc->io_pool, GFP_NOIO);
 960         io->target = ti;
 961         io->base_bio = bio;
 962         io->error = 0;
 963         atomic_set(&io->pending, 0);
 964
 965         if (bio_data_dir(io->base_bio) == READ)
 966                 kcryptd_queue_io(io);
 967         else
 968                 kcryptd_queue_crypt(io);
 969
 970         return DM_MAPIO_SUBMITTED;
 971 }
 972
 973 static int crypt_status(struct dm_target *ti, status_type_t type,
 974                         char *result, unsigned int maxlen)
 975 {
 976         struct crypt_config *cc = (struct crypt_config *) ti->private;
 977         unsigned int sz = 0;
 978
 979         switch (type) {
 980         case STATUSTYPE_INFO:
 981                 result[0] = '\0';
 982                 break;
 983
 984         case STATUSTYPE_TABLE:
 985                 if (cc->iv_mode)
 986                         DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
 987                                cc->iv_mode);
 988                 else
 989                         DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
 990
 991                 if (cc->key_size > 0) {
 992                         if ((maxlen - sz) < ((cc->key_size << 1) + 1))
 993                                 return -ENOMEM;
 994
 995                         crypt_encode_key(result + sz, cc->key, cc->key_size);
 996                         sz += cc->key_size << 1;
 997                 } else {
 998                         if (sz >= maxlen)
 999                                 return -ENOMEM;
1000                         result[sz++] = '-';
1001                 }
1002
1003                 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
1004                                 cc->dev->name, (unsigned long long)cc->start);
1005                 break;
1006         }
1007         return 0;
1008 }
1009
1010 static void crypt_postsuspend(struct dm_target *ti)
1011 {
1012         struct crypt_config *cc = ti->private;
1013
1014         set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1015 }
1016
1017 static int crypt_preresume(struct dm_target *ti)
1018 {
1019         struct crypt_config *cc = ti->private;
1020
1021         if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
1022                 DMERR("aborting resume - crypt key is not set.");
1023                 return -EAGAIN;
1024         }
1025
1026         return 0;
1027 }
1028
1029 static void crypt_resume(struct dm_target *ti)
1030 {
1031         struct crypt_config *cc = ti->private;
1032
1033         clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
1034 }
1035
1036 /* Message interface
1037  *      key set <key>
1038  *      key wipe
1039  */
1040 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
1041 {
1042         struct crypt_config *cc = ti->private;
1043
1044         if (argc < 2)
1045                 goto error;
1046
1047         if (!strnicmp(argv[0], MESG_STR("key"))) {
1048                 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
1049                         DMWARN("not suspended during key manipulation.");
1050                         return -EINVAL;
1051                 }
1052                 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
1053                         return crypt_set_key(cc, argv[2]);
1054                 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
1055                         return crypt_wipe_key(cc);
1056         }
1057
1058 error:
1059         DMWARN("unrecognised message received.");
1060         return -EINVAL;
1061 }
1062
1063 static struct target_type crypt_target = {
1064         .name   = "crypt",
1065         .version= {1, 5, 0},
1066         .module = THIS_MODULE,
1067         .ctr    = crypt_ctr,
1068         .dtr    = crypt_dtr,
1069         .map    = crypt_map,
1070         .status = crypt_status,
1071         .postsuspend = crypt_postsuspend,
1072         .preresume = crypt_preresume,
1073         .resume = crypt_resume,
1074         .message = crypt_message,
1075 };
1076
1077 static int __init dm_crypt_init(void)
1078 {
1079         int r;
1080
1081         _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
1082         if (!_crypt_io_pool)
1083                 return -ENOMEM;
1084
1085         r = dm_register_target(&crypt_target);
1086         if (r < 0) {
1087                 DMERR("register failed %d", r);
1088                 kmem_cache_destroy(_crypt_io_pool);
1089         }
1090
1091         return r;
1092 }
1093
1094 static void __exit dm_crypt_exit(void)
1095 {
1096         int r = dm_unregister_target(&crypt_target);
1097
1098         if (r < 0)
1099                 DMERR("unregister failed %d", r);
1100
1101         kmem_cache_destroy(_crypt_io_pool);
1102 }
1103
1104 module_init(dm_crypt_init);
1105 module_exit(dm_crypt_exit);
1106
1107 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
1108 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
1109 MODULE_LICENSE("GPL");