1 /* 2 * Copyright (C) 2003 Christophe Saout <christophe@saout.de> 3 * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org> 4 * Copyright (C) 2006-2008 Red Hat, Inc. All rights reserved. 5 * 6 * This file is released under the GPL. 7 */ 8 9 #include <linux/completion.h> 10 #include <linux/err.h> 11 #include <linux/module.h> 12 #include <linux/init.h> 13 #include <linux/kernel.h> 14 #include <linux/bio.h> 15 #include <linux/blkdev.h> 16 #include <linux/mempool.h> 17 #include <linux/slab.h> 18 #include <linux/crypto.h> 19 #include <linux/workqueue.h> 20 #include <linux/backing-dev.h> 21 #include <asm/atomic.h> 22 #include <linux/scatterlist.h> 23 #include <asm/page.h> 24 #include <asm/unaligned.h> 25 26 #include "dm.h" 27 28 #define DM_MSG_PREFIX "crypt" 29 #define MESG_STR(x) x, sizeof(x) 30 31 /* 32 * context holding the current state of a multi-part conversion 33 */ 34 struct convert_context { 35 struct completion restart; 36 struct bio *bio_in; 37 struct bio *bio_out; 38 unsigned int offset_in; 39 unsigned int offset_out; 40 unsigned int idx_in; 41 unsigned int idx_out; 42 sector_t sector; 43 atomic_t pending; 44 }; 45 46 /* 47 * per bio private data 48 */ 49 struct dm_crypt_io { 50 struct dm_target *target; 51 struct bio *base_bio; 52 struct work_struct work; 53 54 struct convert_context ctx; 55 56 atomic_t pending; 57 int error; 58 sector_t sector; 59 }; 60 61 struct dm_crypt_request { 62 struct scatterlist sg_in; 63 struct scatterlist sg_out; 64 }; 65 66 struct crypt_config; 67 68 struct crypt_iv_operations { 69 int (*ctr)(struct crypt_config *cc, struct dm_target *ti, 70 const char *opts); 71 void (*dtr)(struct crypt_config *cc); 72 const char *(*status)(struct crypt_config *cc); 73 int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector); 74 }; 75 76 /* 77 * Crypt: maps a linear range of a block device 78 * and encrypts / decrypts at the same time. 79 */ 80 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID }; 81 struct crypt_config { 82 struct dm_dev *dev; 83 sector_t start; 84 85 /* 86 * pool for per bio private data, crypto requests and 87 * encryption requeusts/buffer pages 88 */ 89 mempool_t *io_pool; 90 mempool_t *req_pool; 91 mempool_t *page_pool; 92 struct bio_set *bs; 93 94 struct workqueue_struct *io_queue; 95 struct workqueue_struct *crypt_queue; 96 wait_queue_head_t writeq; 97 98 /* 99 * crypto related data 100 */ 101 struct crypt_iv_operations *iv_gen_ops; 102 char *iv_mode; 103 union { 104 struct crypto_cipher *essiv_tfm; 105 int benbi_shift; 106 } iv_gen_private; 107 sector_t iv_offset; 108 unsigned int iv_size; 109 110 /* 111 * Layout of each crypto request: 112 * 113 * struct ablkcipher_request 114 * context 115 * padding 116 * struct dm_crypt_request 117 * padding 118 * IV 119 * 120 * The padding is added so that dm_crypt_request and the IV are 121 * correctly aligned. 122 */ 123 unsigned int dmreq_start; 124 struct ablkcipher_request *req; 125 126 char cipher[CRYPTO_MAX_ALG_NAME]; 127 char chainmode[CRYPTO_MAX_ALG_NAME]; 128 struct crypto_ablkcipher *tfm; 129 unsigned long flags; 130 unsigned int key_size; 131 u8 key[0]; 132 }; 133 134 #define MIN_IOS 16 135 #define MIN_POOL_PAGES 32 136 #define MIN_BIO_PAGES 8 137 138 static struct kmem_cache *_crypt_io_pool; 139 140 static void clone_init(struct dm_crypt_io *, struct bio *); 141 static void kcryptd_queue_crypt(struct dm_crypt_io *io); 142 143 /* 144 * Different IV generation algorithms: 145 * 146 * plain: the initial vector is the 32-bit little-endian version of the sector 147 * number, padded with zeros if necessary. 148 * 149 * essiv: "encrypted sector|salt initial vector", the sector number is 150 * encrypted with the bulk cipher using a salt as key. The salt 151 * should be derived from the bulk cipher's key via hashing. 152 * 153 * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1 154 * (needed for LRW-32-AES and possible other narrow block modes) 155 * 156 * null: the initial vector is always zero. Provides compatibility with 157 * obsolete loop_fish2 devices. Do not use for new devices. 158 * 159 * plumb: unimplemented, see: 160 * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454 161 */ 162 163 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 164 { 165 memset(iv, 0, cc->iv_size); 166 *(u32 *)iv = cpu_to_le32(sector & 0xffffffff); 167 168 return 0; 169 } 170 171 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, 172 const char *opts) 173 { 174 struct crypto_cipher *essiv_tfm; 175 struct crypto_hash *hash_tfm; 176 struct hash_desc desc; 177 struct scatterlist sg; 178 unsigned int saltsize; 179 u8 *salt; 180 int err; 181 182 if (opts == NULL) { 183 ti->error = "Digest algorithm missing for ESSIV mode"; 184 return -EINVAL; 185 } 186 187 /* Hash the cipher key with the given hash algorithm */ 188 hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC); 189 if (IS_ERR(hash_tfm)) { 190 ti->error = "Error initializing ESSIV hash"; 191 return PTR_ERR(hash_tfm); 192 } 193 194 saltsize = crypto_hash_digestsize(hash_tfm); 195 salt = kmalloc(saltsize, GFP_KERNEL); 196 if (salt == NULL) { 197 ti->error = "Error kmallocing salt storage in ESSIV"; 198 crypto_free_hash(hash_tfm); 199 return -ENOMEM; 200 } 201 202 sg_init_one(&sg, cc->key, cc->key_size); 203 desc.tfm = hash_tfm; 204 desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; 205 err = crypto_hash_digest(&desc, &sg, cc->key_size, salt); 206 crypto_free_hash(hash_tfm); 207 208 if (err) { 209 ti->error = "Error calculating hash in ESSIV"; 210 kfree(salt); 211 return err; 212 } 213 214 /* Setup the essiv_tfm with the given salt */ 215 essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC); 216 if (IS_ERR(essiv_tfm)) { 217 ti->error = "Error allocating crypto tfm for ESSIV"; 218 kfree(salt); 219 return PTR_ERR(essiv_tfm); 220 } 221 if (crypto_cipher_blocksize(essiv_tfm) != 222 crypto_ablkcipher_ivsize(cc->tfm)) { 223 ti->error = "Block size of ESSIV cipher does " 224 "not match IV size of block cipher"; 225 crypto_free_cipher(essiv_tfm); 226 kfree(salt); 227 return -EINVAL; 228 } 229 err = crypto_cipher_setkey(essiv_tfm, salt, saltsize); 230 if (err) { 231 ti->error = "Failed to set key for ESSIV cipher"; 232 crypto_free_cipher(essiv_tfm); 233 kfree(salt); 234 return err; 235 } 236 kfree(salt); 237 238 cc->iv_gen_private.essiv_tfm = essiv_tfm; 239 return 0; 240 } 241 242 static void crypt_iv_essiv_dtr(struct crypt_config *cc) 243 { 244 crypto_free_cipher(cc->iv_gen_private.essiv_tfm); 245 cc->iv_gen_private.essiv_tfm = NULL; 246 } 247 248 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 249 { 250 memset(iv, 0, cc->iv_size); 251 *(u64 *)iv = cpu_to_le64(sector); 252 crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv); 253 return 0; 254 } 255 256 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti, 257 const char *opts) 258 { 259 unsigned bs = crypto_ablkcipher_blocksize(cc->tfm); 260 int log = ilog2(bs); 261 262 /* we need to calculate how far we must shift the sector count 263 * to get the cipher block count, we use this shift in _gen */ 264 265 if (1 << log != bs) { 266 ti->error = "cypher blocksize is not a power of 2"; 267 return -EINVAL; 268 } 269 270 if (log > 9) { 271 ti->error = "cypher blocksize is > 512"; 272 return -EINVAL; 273 } 274 275 cc->iv_gen_private.benbi_shift = 9 - log; 276 277 return 0; 278 } 279 280 static void crypt_iv_benbi_dtr(struct crypt_config *cc) 281 { 282 } 283 284 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 285 { 286 __be64 val; 287 288 memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */ 289 290 val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1); 291 put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64))); 292 293 return 0; 294 } 295 296 static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 297 { 298 memset(iv, 0, cc->iv_size); 299 300 return 0; 301 } 302 303 static struct crypt_iv_operations crypt_iv_plain_ops = { 304 .generator = crypt_iv_plain_gen 305 }; 306 307 static struct crypt_iv_operations crypt_iv_essiv_ops = { 308 .ctr = crypt_iv_essiv_ctr, 309 .dtr = crypt_iv_essiv_dtr, 310 .generator = crypt_iv_essiv_gen 311 }; 312 313 static struct crypt_iv_operations crypt_iv_benbi_ops = { 314 .ctr = crypt_iv_benbi_ctr, 315 .dtr = crypt_iv_benbi_dtr, 316 .generator = crypt_iv_benbi_gen 317 }; 318 319 static struct crypt_iv_operations crypt_iv_null_ops = { 320 .generator = crypt_iv_null_gen 321 }; 322 323 static void crypt_convert_init(struct crypt_config *cc, 324 struct convert_context *ctx, 325 struct bio *bio_out, struct bio *bio_in, 326 sector_t sector) 327 { 328 ctx->bio_in = bio_in; 329 ctx->bio_out = bio_out; 330 ctx->offset_in = 0; 331 ctx->offset_out = 0; 332 ctx->idx_in = bio_in ? bio_in->bi_idx : 0; 333 ctx->idx_out = bio_out ? bio_out->bi_idx : 0; 334 ctx->sector = sector + cc->iv_offset; 335 init_completion(&ctx->restart); 336 atomic_set(&ctx->pending, 1); 337 } 338 339 static int crypt_convert_block(struct crypt_config *cc, 340 struct convert_context *ctx, 341 struct ablkcipher_request *req) 342 { 343 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in); 344 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out); 345 struct dm_crypt_request *dmreq; 346 u8 *iv; 347 int r = 0; 348 349 dmreq = (struct dm_crypt_request *)((char *)req + cc->dmreq_start); 350 iv = (u8 *)ALIGN((unsigned long)(dmreq + 1), 351 crypto_ablkcipher_alignmask(cc->tfm) + 1); 352 353 sg_init_table(&dmreq->sg_in, 1); 354 sg_set_page(&dmreq->sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT, 355 bv_in->bv_offset + ctx->offset_in); 356 357 sg_init_table(&dmreq->sg_out, 1); 358 sg_set_page(&dmreq->sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT, 359 bv_out->bv_offset + ctx->offset_out); 360 361 ctx->offset_in += 1 << SECTOR_SHIFT; 362 if (ctx->offset_in >= bv_in->bv_len) { 363 ctx->offset_in = 0; 364 ctx->idx_in++; 365 } 366 367 ctx->offset_out += 1 << SECTOR_SHIFT; 368 if (ctx->offset_out >= bv_out->bv_len) { 369 ctx->offset_out = 0; 370 ctx->idx_out++; 371 } 372 373 if (cc->iv_gen_ops) { 374 r = cc->iv_gen_ops->generator(cc, iv, ctx->sector); 375 if (r < 0) 376 return r; 377 } 378 379 ablkcipher_request_set_crypt(req, &dmreq->sg_in, &dmreq->sg_out, 380 1 << SECTOR_SHIFT, iv); 381 382 if (bio_data_dir(ctx->bio_in) == WRITE) 383 r = crypto_ablkcipher_encrypt(req); 384 else 385 r = crypto_ablkcipher_decrypt(req); 386 387 return r; 388 } 389 390 static void kcryptd_async_done(struct crypto_async_request *async_req, 391 int error); 392 static void crypt_alloc_req(struct crypt_config *cc, 393 struct convert_context *ctx) 394 { 395 if (!cc->req) 396 cc->req = mempool_alloc(cc->req_pool, GFP_NOIO); 397 ablkcipher_request_set_tfm(cc->req, cc->tfm); 398 ablkcipher_request_set_callback(cc->req, CRYPTO_TFM_REQ_MAY_BACKLOG | 399 CRYPTO_TFM_REQ_MAY_SLEEP, 400 kcryptd_async_done, ctx); 401 } 402 403 /* 404 * Encrypt / decrypt data from one bio to another one (can be the same one) 405 */ 406 static int crypt_convert(struct crypt_config *cc, 407 struct convert_context *ctx) 408 { 409 int r; 410 411 while(ctx->idx_in < ctx->bio_in->bi_vcnt && 412 ctx->idx_out < ctx->bio_out->bi_vcnt) { 413 414 crypt_alloc_req(cc, ctx); 415 416 atomic_inc(&ctx->pending); 417 418 r = crypt_convert_block(cc, ctx, cc->req); 419 420 switch (r) { 421 /* async */ 422 case -EBUSY: 423 wait_for_completion(&ctx->restart); 424 INIT_COMPLETION(ctx->restart); 425 /* fall through*/ 426 case -EINPROGRESS: 427 cc->req = NULL; 428 ctx->sector++; 429 continue; 430 431 /* sync */ 432 case 0: 433 atomic_dec(&ctx->pending); 434 ctx->sector++; 435 continue; 436 437 /* error */ 438 default: 439 atomic_dec(&ctx->pending); 440 return r; 441 } 442 } 443 444 return 0; 445 } 446 447 static void dm_crypt_bio_destructor(struct bio *bio) 448 { 449 struct dm_crypt_io *io = bio->bi_private; 450 struct crypt_config *cc = io->target->private; 451 452 bio_free(bio, cc->bs); 453 } 454 455 /* 456 * Generate a new unfragmented bio with the given size 457 * This should never violate the device limitations 458 * May return a smaller bio when running out of pages 459 */ 460 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size) 461 { 462 struct crypt_config *cc = io->target->private; 463 struct bio *clone; 464 unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 465 gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM; 466 unsigned i, len; 467 struct page *page; 468 469 clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs); 470 if (!clone) 471 return NULL; 472 473 clone_init(io, clone); 474 475 for (i = 0; i < nr_iovecs; i++) { 476 page = mempool_alloc(cc->page_pool, gfp_mask); 477 if (!page) 478 break; 479 480 /* 481 * if additional pages cannot be allocated without waiting, 482 * return a partially allocated bio, the caller will then try 483 * to allocate additional bios while submitting this partial bio 484 */ 485 if (i == (MIN_BIO_PAGES - 1)) 486 gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; 487 488 len = (size > PAGE_SIZE) ? PAGE_SIZE : size; 489 490 if (!bio_add_page(clone, page, len, 0)) { 491 mempool_free(page, cc->page_pool); 492 break; 493 } 494 495 size -= len; 496 } 497 498 if (!clone->bi_size) { 499 bio_put(clone); 500 return NULL; 501 } 502 503 return clone; 504 } 505 506 static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone) 507 { 508 unsigned int i; 509 struct bio_vec *bv; 510 511 for (i = 0; i < clone->bi_vcnt; i++) { 512 bv = bio_iovec_idx(clone, i); 513 BUG_ON(!bv->bv_page); 514 mempool_free(bv->bv_page, cc->page_pool); 515 bv->bv_page = NULL; 516 } 517 } 518 519 /* 520 * One of the bios was finished. Check for completion of 521 * the whole request and correctly clean up the buffer. 522 */ 523 static void crypt_dec_pending(struct dm_crypt_io *io) 524 { 525 struct crypt_config *cc = io->target->private; 526 527 if (!atomic_dec_and_test(&io->pending)) 528 return; 529 530 bio_endio(io->base_bio, io->error); 531 mempool_free(io, cc->io_pool); 532 } 533 534 /* 535 * kcryptd/kcryptd_io: 536 * 537 * Needed because it would be very unwise to do decryption in an 538 * interrupt context. 539 * 540 * kcryptd performs the actual encryption or decryption. 541 * 542 * kcryptd_io performs the IO submission. 543 * 544 * They must be separated as otherwise the final stages could be 545 * starved by new requests which can block in the first stages due 546 * to memory allocation. 547 */ 548 static void crypt_endio(struct bio *clone, int error) 549 { 550 struct dm_crypt_io *io = clone->bi_private; 551 struct crypt_config *cc = io->target->private; 552 unsigned rw = bio_data_dir(clone); 553 554 if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error)) 555 error = -EIO; 556 557 /* 558 * free the processed pages 559 */ 560 if (rw == WRITE) 561 crypt_free_buffer_pages(cc, clone); 562 563 bio_put(clone); 564 565 if (rw == READ && !error) { 566 kcryptd_queue_crypt(io); 567 return; 568 } 569 570 if (unlikely(error)) 571 io->error = error; 572 573 crypt_dec_pending(io); 574 } 575 576 static void clone_init(struct dm_crypt_io *io, struct bio *clone) 577 { 578 struct crypt_config *cc = io->target->private; 579 580 clone->bi_private = io; 581 clone->bi_end_io = crypt_endio; 582 clone->bi_bdev = cc->dev->bdev; 583 clone->bi_rw = io->base_bio->bi_rw; 584 clone->bi_destructor = dm_crypt_bio_destructor; 585 } 586 587 static void kcryptd_io_read(struct dm_crypt_io *io) 588 { 589 struct crypt_config *cc = io->target->private; 590 struct bio *base_bio = io->base_bio; 591 struct bio *clone; 592 593 atomic_inc(&io->pending); 594 595 /* 596 * The block layer might modify the bvec array, so always 597 * copy the required bvecs because we need the original 598 * one in order to decrypt the whole bio data *afterwards*. 599 */ 600 clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs); 601 if (unlikely(!clone)) { 602 io->error = -ENOMEM; 603 crypt_dec_pending(io); 604 return; 605 } 606 607 clone_init(io, clone); 608 clone->bi_idx = 0; 609 clone->bi_vcnt = bio_segments(base_bio); 610 clone->bi_size = base_bio->bi_size; 611 clone->bi_sector = cc->start + io->sector; 612 memcpy(clone->bi_io_vec, bio_iovec(base_bio), 613 sizeof(struct bio_vec) * clone->bi_vcnt); 614 615 generic_make_request(clone); 616 } 617 618 static void kcryptd_io_write(struct dm_crypt_io *io) 619 { 620 struct bio *clone = io->ctx.bio_out; 621 struct crypt_config *cc = io->target->private; 622 623 generic_make_request(clone); 624 wake_up(&cc->writeq); 625 } 626 627 static void kcryptd_io(struct work_struct *work) 628 { 629 struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); 630 631 if (bio_data_dir(io->base_bio) == READ) 632 kcryptd_io_read(io); 633 else 634 kcryptd_io_write(io); 635 } 636 637 static void kcryptd_queue_io(struct dm_crypt_io *io) 638 { 639 struct crypt_config *cc = io->target->private; 640 641 INIT_WORK(&io->work, kcryptd_io); 642 queue_work(cc->io_queue, &io->work); 643 } 644 645 static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, 646 int error, int async) 647 { 648 struct bio *clone = io->ctx.bio_out; 649 struct crypt_config *cc = io->target->private; 650 651 if (unlikely(error < 0)) { 652 crypt_free_buffer_pages(cc, clone); 653 bio_put(clone); 654 io->error = -EIO; 655 return; 656 } 657 658 /* crypt_convert should have filled the clone bio */ 659 BUG_ON(io->ctx.idx_out < clone->bi_vcnt); 660 661 clone->bi_sector = cc->start + io->sector; 662 io->sector += bio_sectors(clone); 663 664 if (async) 665 kcryptd_queue_io(io); 666 else { 667 atomic_inc(&io->pending); 668 generic_make_request(clone); 669 } 670 } 671 672 static void kcryptd_crypt_write_convert_loop(struct dm_crypt_io *io) 673 { 674 struct crypt_config *cc = io->target->private; 675 struct bio *clone; 676 unsigned remaining = io->base_bio->bi_size; 677 int r; 678 679 /* 680 * The allocated buffers can be smaller than the whole bio, 681 * so repeat the whole process until all the data can be handled. 682 */ 683 while (remaining) { 684 clone = crypt_alloc_buffer(io, remaining); 685 if (unlikely(!clone)) { 686 io->error = -ENOMEM; 687 return; 688 } 689 690 io->ctx.bio_out = clone; 691 io->ctx.idx_out = 0; 692 693 remaining -= clone->bi_size; 694 695 r = crypt_convert(cc, &io->ctx); 696 697 if (atomic_dec_and_test(&io->ctx.pending)) { 698 /* processed, no running async crypto */ 699 kcryptd_crypt_write_io_submit(io, r, 0); 700 if (unlikely(r < 0)) 701 return; 702 } else 703 atomic_inc(&io->pending); 704 705 /* out of memory -> run queues */ 706 if (unlikely(remaining)) { 707 /* wait for async crypto then reinitialize pending */ 708 wait_event(cc->writeq, !atomic_read(&io->ctx.pending)); 709 atomic_set(&io->ctx.pending, 1); 710 congestion_wait(WRITE, HZ/100); 711 } 712 } 713 } 714 715 static void kcryptd_crypt_write_convert(struct dm_crypt_io *io) 716 { 717 struct crypt_config *cc = io->target->private; 718 719 /* 720 * Prevent io from disappearing until this function completes. 721 */ 722 atomic_inc(&io->pending); 723 724 crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, io->sector); 725 kcryptd_crypt_write_convert_loop(io); 726 727 crypt_dec_pending(io); 728 } 729 730 static void kcryptd_crypt_read_done(struct dm_crypt_io *io, int error) 731 { 732 if (unlikely(error < 0)) 733 io->error = -EIO; 734 735 crypt_dec_pending(io); 736 } 737 738 static void kcryptd_crypt_read_convert(struct dm_crypt_io *io) 739 { 740 struct crypt_config *cc = io->target->private; 741 int r = 0; 742 743 atomic_inc(&io->pending); 744 745 crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio, 746 io->sector); 747 748 r = crypt_convert(cc, &io->ctx); 749 750 if (atomic_dec_and_test(&io->ctx.pending)) 751 kcryptd_crypt_read_done(io, r); 752 753 crypt_dec_pending(io); 754 } 755 756 static void kcryptd_async_done(struct crypto_async_request *async_req, 757 int error) 758 { 759 struct convert_context *ctx = async_req->data; 760 struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx); 761 struct crypt_config *cc = io->target->private; 762 763 if (error == -EINPROGRESS) { 764 complete(&ctx->restart); 765 return; 766 } 767 768 mempool_free(ablkcipher_request_cast(async_req), cc->req_pool); 769 770 if (!atomic_dec_and_test(&ctx->pending)) 771 return; 772 773 if (bio_data_dir(io->base_bio) == READ) 774 kcryptd_crypt_read_done(io, error); 775 else 776 kcryptd_crypt_write_io_submit(io, error, 1); 777 } 778 779 static void kcryptd_crypt(struct work_struct *work) 780 { 781 struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); 782 783 if (bio_data_dir(io->base_bio) == READ) 784 kcryptd_crypt_read_convert(io); 785 else 786 kcryptd_crypt_write_convert(io); 787 } 788 789 static void kcryptd_queue_crypt(struct dm_crypt_io *io) 790 { 791 struct crypt_config *cc = io->target->private; 792 793 INIT_WORK(&io->work, kcryptd_crypt); 794 queue_work(cc->crypt_queue, &io->work); 795 } 796 797 /* 798 * Decode key from its hex representation 799 */ 800 static int crypt_decode_key(u8 *key, char *hex, unsigned int size) 801 { 802 char buffer[3]; 803 char *endp; 804 unsigned int i; 805 806 buffer[2] = '\0'; 807 808 for (i = 0; i < size; i++) { 809 buffer[0] = *hex++; 810 buffer[1] = *hex++; 811 812 key[i] = (u8)simple_strtoul(buffer, &endp, 16); 813 814 if (endp != &buffer[2]) 815 return -EINVAL; 816 } 817 818 if (*hex != '\0') 819 return -EINVAL; 820 821 return 0; 822 } 823 824 /* 825 * Encode key into its hex representation 826 */ 827 static void crypt_encode_key(char *hex, u8 *key, unsigned int size) 828 { 829 unsigned int i; 830 831 for (i = 0; i < size; i++) { 832 sprintf(hex, "%02x", *key); 833 hex += 2; 834 key++; 835 } 836 } 837 838 static int crypt_set_key(struct crypt_config *cc, char *key) 839 { 840 unsigned key_size = strlen(key) >> 1; 841 842 if (cc->key_size && cc->key_size != key_size) 843 return -EINVAL; 844 845 cc->key_size = key_size; /* initial settings */ 846 847 if ((!key_size && strcmp(key, "-")) || 848 (key_size && crypt_decode_key(cc->key, key, key_size) < 0)) 849 return -EINVAL; 850 851 set_bit(DM_CRYPT_KEY_VALID, &cc->flags); 852 853 return 0; 854 } 855 856 static int crypt_wipe_key(struct crypt_config *cc) 857 { 858 clear_bit(DM_CRYPT_KEY_VALID, &cc->flags); 859 memset(&cc->key, 0, cc->key_size * sizeof(u8)); 860 return 0; 861 } 862 863 /* 864 * Construct an encryption mapping: 865 * <cipher> <key> <iv_offset> <dev_path> <start> 866 */ 867 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) 868 { 869 struct crypt_config *cc; 870 struct crypto_ablkcipher *tfm; 871 char *tmp; 872 char *cipher; 873 char *chainmode; 874 char *ivmode; 875 char *ivopts; 876 unsigned int key_size; 877 unsigned long long tmpll; 878 879 if (argc != 5) { 880 ti->error = "Not enough arguments"; 881 return -EINVAL; 882 } 883 884 tmp = argv[0]; 885 cipher = strsep(&tmp, "-"); 886 chainmode = strsep(&tmp, "-"); 887 ivopts = strsep(&tmp, "-"); 888 ivmode = strsep(&ivopts, ":"); 889 890 if (tmp) 891 DMWARN("Unexpected additional cipher options"); 892 893 key_size = strlen(argv[1]) >> 1; 894 895 cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL); 896 if (cc == NULL) { 897 ti->error = 898 "Cannot allocate transparent encryption context"; 899 return -ENOMEM; 900 } 901 902 if (crypt_set_key(cc, argv[1])) { 903 ti->error = "Error decoding key"; 904 goto bad_cipher; 905 } 906 907 /* Compatiblity mode for old dm-crypt cipher strings */ 908 if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) { 909 chainmode = "cbc"; 910 ivmode = "plain"; 911 } 912 913 if (strcmp(chainmode, "ecb") && !ivmode) { 914 ti->error = "This chaining mode requires an IV mechanism"; 915 goto bad_cipher; 916 } 917 918 if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", 919 chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) { 920 ti->error = "Chain mode + cipher name is too long"; 921 goto bad_cipher; 922 } 923 924 tfm = crypto_alloc_ablkcipher(cc->cipher, 0, 0); 925 if (IS_ERR(tfm)) { 926 ti->error = "Error allocating crypto tfm"; 927 goto bad_cipher; 928 } 929 930 strcpy(cc->cipher, cipher); 931 strcpy(cc->chainmode, chainmode); 932 cc->tfm = tfm; 933 934 /* 935 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi". 936 * See comments at iv code 937 */ 938 939 if (ivmode == NULL) 940 cc->iv_gen_ops = NULL; 941 else if (strcmp(ivmode, "plain") == 0) 942 cc->iv_gen_ops = &crypt_iv_plain_ops; 943 else if (strcmp(ivmode, "essiv") == 0) 944 cc->iv_gen_ops = &crypt_iv_essiv_ops; 945 else if (strcmp(ivmode, "benbi") == 0) 946 cc->iv_gen_ops = &crypt_iv_benbi_ops; 947 else if (strcmp(ivmode, "null") == 0) 948 cc->iv_gen_ops = &crypt_iv_null_ops; 949 else { 950 ti->error = "Invalid IV mode"; 951 goto bad_ivmode; 952 } 953 954 if (cc->iv_gen_ops && cc->iv_gen_ops->ctr && 955 cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) 956 goto bad_ivmode; 957 958 cc->iv_size = crypto_ablkcipher_ivsize(tfm); 959 if (cc->iv_size) 960 /* at least a 64 bit sector number should fit in our buffer */ 961 cc->iv_size = max(cc->iv_size, 962 (unsigned int)(sizeof(u64) / sizeof(u8))); 963 else { 964 if (cc->iv_gen_ops) { 965 DMWARN("Selected cipher does not support IVs"); 966 if (cc->iv_gen_ops->dtr) 967 cc->iv_gen_ops->dtr(cc); 968 cc->iv_gen_ops = NULL; 969 } 970 } 971 972 cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool); 973 if (!cc->io_pool) { 974 ti->error = "Cannot allocate crypt io mempool"; 975 goto bad_slab_pool; 976 } 977 978 cc->dmreq_start = sizeof(struct ablkcipher_request); 979 cc->dmreq_start += crypto_ablkcipher_reqsize(tfm); 980 cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment()); 981 cc->dmreq_start += crypto_ablkcipher_alignmask(tfm) & 982 ~(crypto_tfm_ctx_alignment() - 1); 983 984 cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start + 985 sizeof(struct dm_crypt_request) + cc->iv_size); 986 if (!cc->req_pool) { 987 ti->error = "Cannot allocate crypt request mempool"; 988 goto bad_req_pool; 989 } 990 cc->req = NULL; 991 992 cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0); 993 if (!cc->page_pool) { 994 ti->error = "Cannot allocate page mempool"; 995 goto bad_page_pool; 996 } 997 998 cc->bs = bioset_create(MIN_IOS, MIN_IOS); 999 if (!cc->bs) { 1000 ti->error = "Cannot allocate crypt bioset"; 1001 goto bad_bs; 1002 } 1003 1004 if (crypto_ablkcipher_setkey(tfm, cc->key, key_size) < 0) { 1005 ti->error = "Error setting key"; 1006 goto bad_device; 1007 } 1008 1009 if (sscanf(argv[2], "%llu", &tmpll) != 1) { 1010 ti->error = "Invalid iv_offset sector"; 1011 goto bad_device; 1012 } 1013 cc->iv_offset = tmpll; 1014 1015 if (sscanf(argv[4], "%llu", &tmpll) != 1) { 1016 ti->error = "Invalid device sector"; 1017 goto bad_device; 1018 } 1019 cc->start = tmpll; 1020 1021 if (dm_get_device(ti, argv[3], cc->start, ti->len, 1022 dm_table_get_mode(ti->table), &cc->dev)) { 1023 ti->error = "Device lookup failed"; 1024 goto bad_device; 1025 } 1026 1027 if (ivmode && cc->iv_gen_ops) { 1028 if (ivopts) 1029 *(ivopts - 1) = ':'; 1030 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL); 1031 if (!cc->iv_mode) { 1032 ti->error = "Error kmallocing iv_mode string"; 1033 goto bad_ivmode_string; 1034 } 1035 strcpy(cc->iv_mode, ivmode); 1036 } else 1037 cc->iv_mode = NULL; 1038 1039 cc->io_queue = create_singlethread_workqueue("kcryptd_io"); 1040 if (!cc->io_queue) { 1041 ti->error = "Couldn't create kcryptd io queue"; 1042 goto bad_io_queue; 1043 } 1044 1045 cc->crypt_queue = create_singlethread_workqueue("kcryptd"); 1046 if (!cc->crypt_queue) { 1047 ti->error = "Couldn't create kcryptd queue"; 1048 goto bad_crypt_queue; 1049 } 1050 1051 init_waitqueue_head(&cc->writeq); 1052 ti->private = cc; 1053 return 0; 1054 1055 bad_crypt_queue: 1056 destroy_workqueue(cc->io_queue); 1057 bad_io_queue: 1058 kfree(cc->iv_mode); 1059 bad_ivmode_string: 1060 dm_put_device(ti, cc->dev); 1061 bad_device: 1062 bioset_free(cc->bs); 1063 bad_bs: 1064 mempool_destroy(cc->page_pool); 1065 bad_page_pool: 1066 mempool_destroy(cc->req_pool); 1067 bad_req_pool: 1068 mempool_destroy(cc->io_pool); 1069 bad_slab_pool: 1070 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 1071 cc->iv_gen_ops->dtr(cc); 1072 bad_ivmode: 1073 crypto_free_ablkcipher(tfm); 1074 bad_cipher: 1075 /* Must zero key material before freeing */ 1076 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 1077 kfree(cc); 1078 return -EINVAL; 1079 } 1080 1081 static void crypt_dtr(struct dm_target *ti) 1082 { 1083 struct crypt_config *cc = (struct crypt_config *) ti->private; 1084 1085 destroy_workqueue(cc->io_queue); 1086 destroy_workqueue(cc->crypt_queue); 1087 1088 if (cc->req) 1089 mempool_free(cc->req, cc->req_pool); 1090 1091 bioset_free(cc->bs); 1092 mempool_destroy(cc->page_pool); 1093 mempool_destroy(cc->req_pool); 1094 mempool_destroy(cc->io_pool); 1095 1096 kfree(cc->iv_mode); 1097 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 1098 cc->iv_gen_ops->dtr(cc); 1099 crypto_free_ablkcipher(cc->tfm); 1100 dm_put_device(ti, cc->dev); 1101 1102 /* Must zero key material before freeing */ 1103 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 1104 kfree(cc); 1105 } 1106 1107 static int crypt_map(struct dm_target *ti, struct bio *bio, 1108 union map_info *map_context) 1109 { 1110 struct crypt_config *cc = ti->private; 1111 struct dm_crypt_io *io; 1112 1113 io = mempool_alloc(cc->io_pool, GFP_NOIO); 1114 io->target = ti; 1115 io->base_bio = bio; 1116 io->sector = bio->bi_sector - ti->begin; 1117 io->error = 0; 1118 atomic_set(&io->pending, 0); 1119 1120 if (bio_data_dir(io->base_bio) == READ) 1121 kcryptd_queue_io(io); 1122 else 1123 kcryptd_queue_crypt(io); 1124 1125 return DM_MAPIO_SUBMITTED; 1126 } 1127 1128 static int crypt_status(struct dm_target *ti, status_type_t type, 1129 char *result, unsigned int maxlen) 1130 { 1131 struct crypt_config *cc = (struct crypt_config *) ti->private; 1132 unsigned int sz = 0; 1133 1134 switch (type) { 1135 case STATUSTYPE_INFO: 1136 result[0] = '\0'; 1137 break; 1138 1139 case STATUSTYPE_TABLE: 1140 if (cc->iv_mode) 1141 DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode, 1142 cc->iv_mode); 1143 else 1144 DMEMIT("%s-%s ", cc->cipher, cc->chainmode); 1145 1146 if (cc->key_size > 0) { 1147 if ((maxlen - sz) < ((cc->key_size << 1) + 1)) 1148 return -ENOMEM; 1149 1150 crypt_encode_key(result + sz, cc->key, cc->key_size); 1151 sz += cc->key_size << 1; 1152 } else { 1153 if (sz >= maxlen) 1154 return -ENOMEM; 1155 result[sz++] = '-'; 1156 } 1157 1158 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset, 1159 cc->dev->name, (unsigned long long)cc->start); 1160 break; 1161 } 1162 return 0; 1163 } 1164 1165 static void crypt_postsuspend(struct dm_target *ti) 1166 { 1167 struct crypt_config *cc = ti->private; 1168 1169 set_bit(DM_CRYPT_SUSPENDED, &cc->flags); 1170 } 1171 1172 static int crypt_preresume(struct dm_target *ti) 1173 { 1174 struct crypt_config *cc = ti->private; 1175 1176 if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) { 1177 DMERR("aborting resume - crypt key is not set."); 1178 return -EAGAIN; 1179 } 1180 1181 return 0; 1182 } 1183 1184 static void crypt_resume(struct dm_target *ti) 1185 { 1186 struct crypt_config *cc = ti->private; 1187 1188 clear_bit(DM_CRYPT_SUSPENDED, &cc->flags); 1189 } 1190 1191 /* Message interface 1192 * key set <key> 1193 * key wipe 1194 */ 1195 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv) 1196 { 1197 struct crypt_config *cc = ti->private; 1198 1199 if (argc < 2) 1200 goto error; 1201 1202 if (!strnicmp(argv[0], MESG_STR("key"))) { 1203 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) { 1204 DMWARN("not suspended during key manipulation."); 1205 return -EINVAL; 1206 } 1207 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set"))) 1208 return crypt_set_key(cc, argv[2]); 1209 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe"))) 1210 return crypt_wipe_key(cc); 1211 } 1212 1213 error: 1214 DMWARN("unrecognised message received."); 1215 return -EINVAL; 1216 } 1217 1218 static struct target_type crypt_target = { 1219 .name = "crypt", 1220 .version= {1, 5, 0}, 1221 .module = THIS_MODULE, 1222 .ctr = crypt_ctr, 1223 .dtr = crypt_dtr, 1224 .map = crypt_map, 1225 .status = crypt_status, 1226 .postsuspend = crypt_postsuspend, 1227 .preresume = crypt_preresume, 1228 .resume = crypt_resume, 1229 .message = crypt_message, 1230 }; 1231 1232 static int __init dm_crypt_init(void) 1233 { 1234 int r; 1235 1236 _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0); 1237 if (!_crypt_io_pool) 1238 return -ENOMEM; 1239 1240 r = dm_register_target(&crypt_target); 1241 if (r < 0) { 1242 DMERR("register failed %d", r); 1243 kmem_cache_destroy(_crypt_io_pool); 1244 } 1245 1246 return r; 1247 } 1248 1249 static void __exit dm_crypt_exit(void) 1250 { 1251 int r = dm_unregister_target(&crypt_target); 1252 1253 if (r < 0) 1254 DMERR("unregister failed %d", r); 1255 1256 kmem_cache_destroy(_crypt_io_pool); 1257 } 1258 1259 module_init(dm_crypt_init); 1260 module_exit(dm_crypt_exit); 1261 1262 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>"); 1263 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption"); 1264 MODULE_LICENSE("GPL"); 1265