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 cond_resched(); 436 continue; 437 438 /* error */ 439 default: 440 atomic_dec(&ctx->pending); 441 return r; 442 } 443 } 444 445 return 0; 446 } 447 448 static void dm_crypt_bio_destructor(struct bio *bio) 449 { 450 struct dm_crypt_io *io = bio->bi_private; 451 struct crypt_config *cc = io->target->private; 452 453 bio_free(bio, cc->bs); 454 } 455 456 /* 457 * Generate a new unfragmented bio with the given size 458 * This should never violate the device limitations 459 * May return a smaller bio when running out of pages 460 */ 461 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size) 462 { 463 struct crypt_config *cc = io->target->private; 464 struct bio *clone; 465 unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 466 gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM; 467 unsigned i, len; 468 struct page *page; 469 470 clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs); 471 if (!clone) 472 return NULL; 473 474 clone_init(io, clone); 475 476 for (i = 0; i < nr_iovecs; i++) { 477 page = mempool_alloc(cc->page_pool, gfp_mask); 478 if (!page) 479 break; 480 481 /* 482 * if additional pages cannot be allocated without waiting, 483 * return a partially allocated bio, the caller will then try 484 * to allocate additional bios while submitting this partial bio 485 */ 486 if (i == (MIN_BIO_PAGES - 1)) 487 gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; 488 489 len = (size > PAGE_SIZE) ? PAGE_SIZE : size; 490 491 if (!bio_add_page(clone, page, len, 0)) { 492 mempool_free(page, cc->page_pool); 493 break; 494 } 495 496 size -= len; 497 } 498 499 if (!clone->bi_size) { 500 bio_put(clone); 501 return NULL; 502 } 503 504 return clone; 505 } 506 507 static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone) 508 { 509 unsigned int i; 510 struct bio_vec *bv; 511 512 for (i = 0; i < clone->bi_vcnt; i++) { 513 bv = bio_iovec_idx(clone, i); 514 BUG_ON(!bv->bv_page); 515 mempool_free(bv->bv_page, cc->page_pool); 516 bv->bv_page = NULL; 517 } 518 } 519 520 /* 521 * One of the bios was finished. Check for completion of 522 * the whole request and correctly clean up the buffer. 523 */ 524 static void crypt_dec_pending(struct dm_crypt_io *io) 525 { 526 struct crypt_config *cc = io->target->private; 527 528 if (!atomic_dec_and_test(&io->pending)) 529 return; 530 531 bio_endio(io->base_bio, io->error); 532 mempool_free(io, cc->io_pool); 533 } 534 535 /* 536 * kcryptd/kcryptd_io: 537 * 538 * Needed because it would be very unwise to do decryption in an 539 * interrupt context. 540 * 541 * kcryptd performs the actual encryption or decryption. 542 * 543 * kcryptd_io performs the IO submission. 544 * 545 * They must be separated as otherwise the final stages could be 546 * starved by new requests which can block in the first stages due 547 * to memory allocation. 548 */ 549 static void crypt_endio(struct bio *clone, int error) 550 { 551 struct dm_crypt_io *io = clone->bi_private; 552 struct crypt_config *cc = io->target->private; 553 unsigned rw = bio_data_dir(clone); 554 555 if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error)) 556 error = -EIO; 557 558 /* 559 * free the processed pages 560 */ 561 if (rw == WRITE) 562 crypt_free_buffer_pages(cc, clone); 563 564 bio_put(clone); 565 566 if (rw == READ && !error) { 567 kcryptd_queue_crypt(io); 568 return; 569 } 570 571 if (unlikely(error)) 572 io->error = error; 573 574 crypt_dec_pending(io); 575 } 576 577 static void clone_init(struct dm_crypt_io *io, struct bio *clone) 578 { 579 struct crypt_config *cc = io->target->private; 580 581 clone->bi_private = io; 582 clone->bi_end_io = crypt_endio; 583 clone->bi_bdev = cc->dev->bdev; 584 clone->bi_rw = io->base_bio->bi_rw; 585 clone->bi_destructor = dm_crypt_bio_destructor; 586 } 587 588 static void kcryptd_io_read(struct dm_crypt_io *io) 589 { 590 struct crypt_config *cc = io->target->private; 591 struct bio *base_bio = io->base_bio; 592 struct bio *clone; 593 594 atomic_inc(&io->pending); 595 596 /* 597 * The block layer might modify the bvec array, so always 598 * copy the required bvecs because we need the original 599 * one in order to decrypt the whole bio data *afterwards*. 600 */ 601 clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs); 602 if (unlikely(!clone)) { 603 io->error = -ENOMEM; 604 crypt_dec_pending(io); 605 return; 606 } 607 608 clone_init(io, clone); 609 clone->bi_idx = 0; 610 clone->bi_vcnt = bio_segments(base_bio); 611 clone->bi_size = base_bio->bi_size; 612 clone->bi_sector = cc->start + io->sector; 613 memcpy(clone->bi_io_vec, bio_iovec(base_bio), 614 sizeof(struct bio_vec) * clone->bi_vcnt); 615 616 generic_make_request(clone); 617 } 618 619 static void kcryptd_io_write(struct dm_crypt_io *io) 620 { 621 struct bio *clone = io->ctx.bio_out; 622 struct crypt_config *cc = io->target->private; 623 624 generic_make_request(clone); 625 wake_up(&cc->writeq); 626 } 627 628 static void kcryptd_io(struct work_struct *work) 629 { 630 struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); 631 632 if (bio_data_dir(io->base_bio) == READ) 633 kcryptd_io_read(io); 634 else 635 kcryptd_io_write(io); 636 } 637 638 static void kcryptd_queue_io(struct dm_crypt_io *io) 639 { 640 struct crypt_config *cc = io->target->private; 641 642 INIT_WORK(&io->work, kcryptd_io); 643 queue_work(cc->io_queue, &io->work); 644 } 645 646 static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, 647 int error, int async) 648 { 649 struct bio *clone = io->ctx.bio_out; 650 struct crypt_config *cc = io->target->private; 651 652 if (unlikely(error < 0)) { 653 crypt_free_buffer_pages(cc, clone); 654 bio_put(clone); 655 io->error = -EIO; 656 return; 657 } 658 659 /* crypt_convert should have filled the clone bio */ 660 BUG_ON(io->ctx.idx_out < clone->bi_vcnt); 661 662 clone->bi_sector = cc->start + io->sector; 663 io->sector += bio_sectors(clone); 664 665 if (async) 666 kcryptd_queue_io(io); 667 else { 668 atomic_inc(&io->pending); 669 generic_make_request(clone); 670 } 671 } 672 673 static void kcryptd_crypt_write_convert_loop(struct dm_crypt_io *io) 674 { 675 struct crypt_config *cc = io->target->private; 676 struct bio *clone; 677 unsigned remaining = io->base_bio->bi_size; 678 int r; 679 680 /* 681 * The allocated buffers can be smaller than the whole bio, 682 * so repeat the whole process until all the data can be handled. 683 */ 684 while (remaining) { 685 clone = crypt_alloc_buffer(io, remaining); 686 if (unlikely(!clone)) { 687 io->error = -ENOMEM; 688 return; 689 } 690 691 io->ctx.bio_out = clone; 692 io->ctx.idx_out = 0; 693 694 remaining -= clone->bi_size; 695 696 r = crypt_convert(cc, &io->ctx); 697 698 if (atomic_dec_and_test(&io->ctx.pending)) { 699 /* processed, no running async crypto */ 700 kcryptd_crypt_write_io_submit(io, r, 0); 701 if (unlikely(r < 0)) 702 return; 703 } else 704 atomic_inc(&io->pending); 705 706 /* out of memory -> run queues */ 707 if (unlikely(remaining)) { 708 /* wait for async crypto then reinitialize pending */ 709 wait_event(cc->writeq, !atomic_read(&io->ctx.pending)); 710 atomic_set(&io->ctx.pending, 1); 711 congestion_wait(WRITE, HZ/100); 712 } 713 } 714 } 715 716 static void kcryptd_crypt_write_convert(struct dm_crypt_io *io) 717 { 718 struct crypt_config *cc = io->target->private; 719 720 /* 721 * Prevent io from disappearing until this function completes. 722 */ 723 atomic_inc(&io->pending); 724 725 crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, io->sector); 726 kcryptd_crypt_write_convert_loop(io); 727 728 crypt_dec_pending(io); 729 } 730 731 static void kcryptd_crypt_read_done(struct dm_crypt_io *io, int error) 732 { 733 if (unlikely(error < 0)) 734 io->error = -EIO; 735 736 crypt_dec_pending(io); 737 } 738 739 static void kcryptd_crypt_read_convert(struct dm_crypt_io *io) 740 { 741 struct crypt_config *cc = io->target->private; 742 int r = 0; 743 744 atomic_inc(&io->pending); 745 746 crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio, 747 io->sector); 748 749 r = crypt_convert(cc, &io->ctx); 750 751 if (atomic_dec_and_test(&io->ctx.pending)) 752 kcryptd_crypt_read_done(io, r); 753 754 crypt_dec_pending(io); 755 } 756 757 static void kcryptd_async_done(struct crypto_async_request *async_req, 758 int error) 759 { 760 struct convert_context *ctx = async_req->data; 761 struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx); 762 struct crypt_config *cc = io->target->private; 763 764 if (error == -EINPROGRESS) { 765 complete(&ctx->restart); 766 return; 767 } 768 769 mempool_free(ablkcipher_request_cast(async_req), cc->req_pool); 770 771 if (!atomic_dec_and_test(&ctx->pending)) 772 return; 773 774 if (bio_data_dir(io->base_bio) == READ) 775 kcryptd_crypt_read_done(io, error); 776 else 777 kcryptd_crypt_write_io_submit(io, error, 1); 778 } 779 780 static void kcryptd_crypt(struct work_struct *work) 781 { 782 struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); 783 784 if (bio_data_dir(io->base_bio) == READ) 785 kcryptd_crypt_read_convert(io); 786 else 787 kcryptd_crypt_write_convert(io); 788 } 789 790 static void kcryptd_queue_crypt(struct dm_crypt_io *io) 791 { 792 struct crypt_config *cc = io->target->private; 793 794 INIT_WORK(&io->work, kcryptd_crypt); 795 queue_work(cc->crypt_queue, &io->work); 796 } 797 798 /* 799 * Decode key from its hex representation 800 */ 801 static int crypt_decode_key(u8 *key, char *hex, unsigned int size) 802 { 803 char buffer[3]; 804 char *endp; 805 unsigned int i; 806 807 buffer[2] = '\0'; 808 809 for (i = 0; i < size; i++) { 810 buffer[0] = *hex++; 811 buffer[1] = *hex++; 812 813 key[i] = (u8)simple_strtoul(buffer, &endp, 16); 814 815 if (endp != &buffer[2]) 816 return -EINVAL; 817 } 818 819 if (*hex != '\0') 820 return -EINVAL; 821 822 return 0; 823 } 824 825 /* 826 * Encode key into its hex representation 827 */ 828 static void crypt_encode_key(char *hex, u8 *key, unsigned int size) 829 { 830 unsigned int i; 831 832 for (i = 0; i < size; i++) { 833 sprintf(hex, "%02x", *key); 834 hex += 2; 835 key++; 836 } 837 } 838 839 static int crypt_set_key(struct crypt_config *cc, char *key) 840 { 841 unsigned key_size = strlen(key) >> 1; 842 843 if (cc->key_size && cc->key_size != key_size) 844 return -EINVAL; 845 846 cc->key_size = key_size; /* initial settings */ 847 848 if ((!key_size && strcmp(key, "-")) || 849 (key_size && crypt_decode_key(cc->key, key, key_size) < 0)) 850 return -EINVAL; 851 852 set_bit(DM_CRYPT_KEY_VALID, &cc->flags); 853 854 return 0; 855 } 856 857 static int crypt_wipe_key(struct crypt_config *cc) 858 { 859 clear_bit(DM_CRYPT_KEY_VALID, &cc->flags); 860 memset(&cc->key, 0, cc->key_size * sizeof(u8)); 861 return 0; 862 } 863 864 /* 865 * Construct an encryption mapping: 866 * <cipher> <key> <iv_offset> <dev_path> <start> 867 */ 868 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) 869 { 870 struct crypt_config *cc; 871 struct crypto_ablkcipher *tfm; 872 char *tmp; 873 char *cipher; 874 char *chainmode; 875 char *ivmode; 876 char *ivopts; 877 unsigned int key_size; 878 unsigned long long tmpll; 879 880 if (argc != 5) { 881 ti->error = "Not enough arguments"; 882 return -EINVAL; 883 } 884 885 tmp = argv[0]; 886 cipher = strsep(&tmp, "-"); 887 chainmode = strsep(&tmp, "-"); 888 ivopts = strsep(&tmp, "-"); 889 ivmode = strsep(&ivopts, ":"); 890 891 if (tmp) 892 DMWARN("Unexpected additional cipher options"); 893 894 key_size = strlen(argv[1]) >> 1; 895 896 cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL); 897 if (cc == NULL) { 898 ti->error = 899 "Cannot allocate transparent encryption context"; 900 return -ENOMEM; 901 } 902 903 if (crypt_set_key(cc, argv[1])) { 904 ti->error = "Error decoding key"; 905 goto bad_cipher; 906 } 907 908 /* Compatiblity mode for old dm-crypt cipher strings */ 909 if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) { 910 chainmode = "cbc"; 911 ivmode = "plain"; 912 } 913 914 if (strcmp(chainmode, "ecb") && !ivmode) { 915 ti->error = "This chaining mode requires an IV mechanism"; 916 goto bad_cipher; 917 } 918 919 if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", 920 chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) { 921 ti->error = "Chain mode + cipher name is too long"; 922 goto bad_cipher; 923 } 924 925 tfm = crypto_alloc_ablkcipher(cc->cipher, 0, 0); 926 if (IS_ERR(tfm)) { 927 ti->error = "Error allocating crypto tfm"; 928 goto bad_cipher; 929 } 930 931 strcpy(cc->cipher, cipher); 932 strcpy(cc->chainmode, chainmode); 933 cc->tfm = tfm; 934 935 /* 936 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi". 937 * See comments at iv code 938 */ 939 940 if (ivmode == NULL) 941 cc->iv_gen_ops = NULL; 942 else if (strcmp(ivmode, "plain") == 0) 943 cc->iv_gen_ops = &crypt_iv_plain_ops; 944 else if (strcmp(ivmode, "essiv") == 0) 945 cc->iv_gen_ops = &crypt_iv_essiv_ops; 946 else if (strcmp(ivmode, "benbi") == 0) 947 cc->iv_gen_ops = &crypt_iv_benbi_ops; 948 else if (strcmp(ivmode, "null") == 0) 949 cc->iv_gen_ops = &crypt_iv_null_ops; 950 else { 951 ti->error = "Invalid IV mode"; 952 goto bad_ivmode; 953 } 954 955 if (cc->iv_gen_ops && cc->iv_gen_ops->ctr && 956 cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) 957 goto bad_ivmode; 958 959 cc->iv_size = crypto_ablkcipher_ivsize(tfm); 960 if (cc->iv_size) 961 /* at least a 64 bit sector number should fit in our buffer */ 962 cc->iv_size = max(cc->iv_size, 963 (unsigned int)(sizeof(u64) / sizeof(u8))); 964 else { 965 if (cc->iv_gen_ops) { 966 DMWARN("Selected cipher does not support IVs"); 967 if (cc->iv_gen_ops->dtr) 968 cc->iv_gen_ops->dtr(cc); 969 cc->iv_gen_ops = NULL; 970 } 971 } 972 973 cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool); 974 if (!cc->io_pool) { 975 ti->error = "Cannot allocate crypt io mempool"; 976 goto bad_slab_pool; 977 } 978 979 cc->dmreq_start = sizeof(struct ablkcipher_request); 980 cc->dmreq_start += crypto_ablkcipher_reqsize(tfm); 981 cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment()); 982 cc->dmreq_start += crypto_ablkcipher_alignmask(tfm) & 983 ~(crypto_tfm_ctx_alignment() - 1); 984 985 cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start + 986 sizeof(struct dm_crypt_request) + cc->iv_size); 987 if (!cc->req_pool) { 988 ti->error = "Cannot allocate crypt request mempool"; 989 goto bad_req_pool; 990 } 991 cc->req = NULL; 992 993 cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0); 994 if (!cc->page_pool) { 995 ti->error = "Cannot allocate page mempool"; 996 goto bad_page_pool; 997 } 998 999 cc->bs = bioset_create(MIN_IOS, MIN_IOS); 1000 if (!cc->bs) { 1001 ti->error = "Cannot allocate crypt bioset"; 1002 goto bad_bs; 1003 } 1004 1005 if (crypto_ablkcipher_setkey(tfm, cc->key, key_size) < 0) { 1006 ti->error = "Error setting key"; 1007 goto bad_device; 1008 } 1009 1010 if (sscanf(argv[2], "%llu", &tmpll) != 1) { 1011 ti->error = "Invalid iv_offset sector"; 1012 goto bad_device; 1013 } 1014 cc->iv_offset = tmpll; 1015 1016 if (sscanf(argv[4], "%llu", &tmpll) != 1) { 1017 ti->error = "Invalid device sector"; 1018 goto bad_device; 1019 } 1020 cc->start = tmpll; 1021 1022 if (dm_get_device(ti, argv[3], cc->start, ti->len, 1023 dm_table_get_mode(ti->table), &cc->dev)) { 1024 ti->error = "Device lookup failed"; 1025 goto bad_device; 1026 } 1027 1028 if (ivmode && cc->iv_gen_ops) { 1029 if (ivopts) 1030 *(ivopts - 1) = ':'; 1031 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL); 1032 if (!cc->iv_mode) { 1033 ti->error = "Error kmallocing iv_mode string"; 1034 goto bad_ivmode_string; 1035 } 1036 strcpy(cc->iv_mode, ivmode); 1037 } else 1038 cc->iv_mode = NULL; 1039 1040 cc->io_queue = create_singlethread_workqueue("kcryptd_io"); 1041 if (!cc->io_queue) { 1042 ti->error = "Couldn't create kcryptd io queue"; 1043 goto bad_io_queue; 1044 } 1045 1046 cc->crypt_queue = create_singlethread_workqueue("kcryptd"); 1047 if (!cc->crypt_queue) { 1048 ti->error = "Couldn't create kcryptd queue"; 1049 goto bad_crypt_queue; 1050 } 1051 1052 init_waitqueue_head(&cc->writeq); 1053 ti->private = cc; 1054 return 0; 1055 1056 bad_crypt_queue: 1057 destroy_workqueue(cc->io_queue); 1058 bad_io_queue: 1059 kfree(cc->iv_mode); 1060 bad_ivmode_string: 1061 dm_put_device(ti, cc->dev); 1062 bad_device: 1063 bioset_free(cc->bs); 1064 bad_bs: 1065 mempool_destroy(cc->page_pool); 1066 bad_page_pool: 1067 mempool_destroy(cc->req_pool); 1068 bad_req_pool: 1069 mempool_destroy(cc->io_pool); 1070 bad_slab_pool: 1071 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 1072 cc->iv_gen_ops->dtr(cc); 1073 bad_ivmode: 1074 crypto_free_ablkcipher(tfm); 1075 bad_cipher: 1076 /* Must zero key material before freeing */ 1077 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 1078 kfree(cc); 1079 return -EINVAL; 1080 } 1081 1082 static void crypt_dtr(struct dm_target *ti) 1083 { 1084 struct crypt_config *cc = (struct crypt_config *) ti->private; 1085 1086 destroy_workqueue(cc->io_queue); 1087 destroy_workqueue(cc->crypt_queue); 1088 1089 if (cc->req) 1090 mempool_free(cc->req, cc->req_pool); 1091 1092 bioset_free(cc->bs); 1093 mempool_destroy(cc->page_pool); 1094 mempool_destroy(cc->req_pool); 1095 mempool_destroy(cc->io_pool); 1096 1097 kfree(cc->iv_mode); 1098 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 1099 cc->iv_gen_ops->dtr(cc); 1100 crypto_free_ablkcipher(cc->tfm); 1101 dm_put_device(ti, cc->dev); 1102 1103 /* Must zero key material before freeing */ 1104 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 1105 kfree(cc); 1106 } 1107 1108 static int crypt_map(struct dm_target *ti, struct bio *bio, 1109 union map_info *map_context) 1110 { 1111 struct crypt_config *cc = ti->private; 1112 struct dm_crypt_io *io; 1113 1114 io = mempool_alloc(cc->io_pool, GFP_NOIO); 1115 io->target = ti; 1116 io->base_bio = bio; 1117 io->sector = bio->bi_sector - ti->begin; 1118 io->error = 0; 1119 atomic_set(&io->pending, 0); 1120 1121 if (bio_data_dir(io->base_bio) == READ) 1122 kcryptd_queue_io(io); 1123 else 1124 kcryptd_queue_crypt(io); 1125 1126 return DM_MAPIO_SUBMITTED; 1127 } 1128 1129 static int crypt_status(struct dm_target *ti, status_type_t type, 1130 char *result, unsigned int maxlen) 1131 { 1132 struct crypt_config *cc = (struct crypt_config *) ti->private; 1133 unsigned int sz = 0; 1134 1135 switch (type) { 1136 case STATUSTYPE_INFO: 1137 result[0] = '\0'; 1138 break; 1139 1140 case STATUSTYPE_TABLE: 1141 if (cc->iv_mode) 1142 DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode, 1143 cc->iv_mode); 1144 else 1145 DMEMIT("%s-%s ", cc->cipher, cc->chainmode); 1146 1147 if (cc->key_size > 0) { 1148 if ((maxlen - sz) < ((cc->key_size << 1) + 1)) 1149 return -ENOMEM; 1150 1151 crypt_encode_key(result + sz, cc->key, cc->key_size); 1152 sz += cc->key_size << 1; 1153 } else { 1154 if (sz >= maxlen) 1155 return -ENOMEM; 1156 result[sz++] = '-'; 1157 } 1158 1159 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset, 1160 cc->dev->name, (unsigned long long)cc->start); 1161 break; 1162 } 1163 return 0; 1164 } 1165 1166 static void crypt_postsuspend(struct dm_target *ti) 1167 { 1168 struct crypt_config *cc = ti->private; 1169 1170 set_bit(DM_CRYPT_SUSPENDED, &cc->flags); 1171 } 1172 1173 static int crypt_preresume(struct dm_target *ti) 1174 { 1175 struct crypt_config *cc = ti->private; 1176 1177 if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) { 1178 DMERR("aborting resume - crypt key is not set."); 1179 return -EAGAIN; 1180 } 1181 1182 return 0; 1183 } 1184 1185 static void crypt_resume(struct dm_target *ti) 1186 { 1187 struct crypt_config *cc = ti->private; 1188 1189 clear_bit(DM_CRYPT_SUSPENDED, &cc->flags); 1190 } 1191 1192 /* Message interface 1193 * key set <key> 1194 * key wipe 1195 */ 1196 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv) 1197 { 1198 struct crypt_config *cc = ti->private; 1199 1200 if (argc < 2) 1201 goto error; 1202 1203 if (!strnicmp(argv[0], MESG_STR("key"))) { 1204 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) { 1205 DMWARN("not suspended during key manipulation."); 1206 return -EINVAL; 1207 } 1208 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set"))) 1209 return crypt_set_key(cc, argv[2]); 1210 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe"))) 1211 return crypt_wipe_key(cc); 1212 } 1213 1214 error: 1215 DMWARN("unrecognised message received."); 1216 return -EINVAL; 1217 } 1218 1219 static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 1220 struct bio_vec *biovec, int max_size) 1221 { 1222 struct crypt_config *cc = ti->private; 1223 struct request_queue *q = bdev_get_queue(cc->dev->bdev); 1224 1225 if (!q->merge_bvec_fn) 1226 return max_size; 1227 1228 bvm->bi_bdev = cc->dev->bdev; 1229 bvm->bi_sector = cc->start + bvm->bi_sector - ti->begin; 1230 1231 return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); 1232 } 1233 1234 static struct target_type crypt_target = { 1235 .name = "crypt", 1236 .version= {1, 6, 0}, 1237 .module = THIS_MODULE, 1238 .ctr = crypt_ctr, 1239 .dtr = crypt_dtr, 1240 .map = crypt_map, 1241 .status = crypt_status, 1242 .postsuspend = crypt_postsuspend, 1243 .preresume = crypt_preresume, 1244 .resume = crypt_resume, 1245 .message = crypt_message, 1246 .merge = crypt_merge, 1247 }; 1248 1249 static int __init dm_crypt_init(void) 1250 { 1251 int r; 1252 1253 _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0); 1254 if (!_crypt_io_pool) 1255 return -ENOMEM; 1256 1257 r = dm_register_target(&crypt_target); 1258 if (r < 0) { 1259 DMERR("register failed %d", r); 1260 kmem_cache_destroy(_crypt_io_pool); 1261 } 1262 1263 return r; 1264 } 1265 1266 static void __exit dm_crypt_exit(void) 1267 { 1268 int r = dm_unregister_target(&crypt_target); 1269 1270 if (r < 0) 1271 DMERR("unregister failed %d", r); 1272 1273 kmem_cache_destroy(_crypt_io_pool); 1274 } 1275 1276 module_init(dm_crypt_init); 1277 module_exit(dm_crypt_exit); 1278 1279 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>"); 1280 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption"); 1281 MODULE_LICENSE("GPL"); 1282