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 <linux/device-mapper.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 struct dm_crypt_io *base_io; 60 }; 61 62 struct dm_crypt_request { 63 struct scatterlist sg_in; 64 struct scatterlist sg_out; 65 }; 66 67 struct crypt_config; 68 69 struct crypt_iv_operations { 70 int (*ctr)(struct crypt_config *cc, struct dm_target *ti, 71 const char *opts); 72 void (*dtr)(struct crypt_config *cc); 73 const char *(*status)(struct crypt_config *cc); 74 int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector); 75 }; 76 77 /* 78 * Crypt: maps a linear range of a block device 79 * and encrypts / decrypts at the same time. 80 */ 81 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID }; 82 struct crypt_config { 83 struct dm_dev *dev; 84 sector_t start; 85 86 /* 87 * pool for per bio private data, crypto requests and 88 * encryption requeusts/buffer pages 89 */ 90 mempool_t *io_pool; 91 mempool_t *req_pool; 92 mempool_t *page_pool; 93 struct bio_set *bs; 94 95 struct workqueue_struct *io_queue; 96 struct workqueue_struct *crypt_queue; 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 } 337 338 static int crypt_convert_block(struct crypt_config *cc, 339 struct convert_context *ctx, 340 struct ablkcipher_request *req) 341 { 342 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in); 343 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out); 344 struct dm_crypt_request *dmreq; 345 u8 *iv; 346 int r = 0; 347 348 dmreq = (struct dm_crypt_request *)((char *)req + cc->dmreq_start); 349 iv = (u8 *)ALIGN((unsigned long)(dmreq + 1), 350 crypto_ablkcipher_alignmask(cc->tfm) + 1); 351 352 sg_init_table(&dmreq->sg_in, 1); 353 sg_set_page(&dmreq->sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT, 354 bv_in->bv_offset + ctx->offset_in); 355 356 sg_init_table(&dmreq->sg_out, 1); 357 sg_set_page(&dmreq->sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT, 358 bv_out->bv_offset + ctx->offset_out); 359 360 ctx->offset_in += 1 << SECTOR_SHIFT; 361 if (ctx->offset_in >= bv_in->bv_len) { 362 ctx->offset_in = 0; 363 ctx->idx_in++; 364 } 365 366 ctx->offset_out += 1 << SECTOR_SHIFT; 367 if (ctx->offset_out >= bv_out->bv_len) { 368 ctx->offset_out = 0; 369 ctx->idx_out++; 370 } 371 372 if (cc->iv_gen_ops) { 373 r = cc->iv_gen_ops->generator(cc, iv, ctx->sector); 374 if (r < 0) 375 return r; 376 } 377 378 ablkcipher_request_set_crypt(req, &dmreq->sg_in, &dmreq->sg_out, 379 1 << SECTOR_SHIFT, iv); 380 381 if (bio_data_dir(ctx->bio_in) == WRITE) 382 r = crypto_ablkcipher_encrypt(req); 383 else 384 r = crypto_ablkcipher_decrypt(req); 385 386 return r; 387 } 388 389 static void kcryptd_async_done(struct crypto_async_request *async_req, 390 int error); 391 static void crypt_alloc_req(struct crypt_config *cc, 392 struct convert_context *ctx) 393 { 394 if (!cc->req) 395 cc->req = mempool_alloc(cc->req_pool, GFP_NOIO); 396 ablkcipher_request_set_tfm(cc->req, cc->tfm); 397 ablkcipher_request_set_callback(cc->req, CRYPTO_TFM_REQ_MAY_BACKLOG | 398 CRYPTO_TFM_REQ_MAY_SLEEP, 399 kcryptd_async_done, ctx); 400 } 401 402 /* 403 * Encrypt / decrypt data from one bio to another one (can be the same one) 404 */ 405 static int crypt_convert(struct crypt_config *cc, 406 struct convert_context *ctx) 407 { 408 int r; 409 410 atomic_set(&ctx->pending, 1); 411 412 while(ctx->idx_in < ctx->bio_in->bi_vcnt && 413 ctx->idx_out < ctx->bio_out->bi_vcnt) { 414 415 crypt_alloc_req(cc, ctx); 416 417 atomic_inc(&ctx->pending); 418 419 r = crypt_convert_block(cc, ctx, cc->req); 420 421 switch (r) { 422 /* async */ 423 case -EBUSY: 424 wait_for_completion(&ctx->restart); 425 INIT_COMPLETION(ctx->restart); 426 /* fall through*/ 427 case -EINPROGRESS: 428 cc->req = NULL; 429 ctx->sector++; 430 continue; 431 432 /* sync */ 433 case 0: 434 atomic_dec(&ctx->pending); 435 ctx->sector++; 436 cond_resched(); 437 continue; 438 439 /* error */ 440 default: 441 atomic_dec(&ctx->pending); 442 return r; 443 } 444 } 445 446 return 0; 447 } 448 449 static void dm_crypt_bio_destructor(struct bio *bio) 450 { 451 struct dm_crypt_io *io = bio->bi_private; 452 struct crypt_config *cc = io->target->private; 453 454 bio_free(bio, cc->bs); 455 } 456 457 /* 458 * Generate a new unfragmented bio with the given size 459 * This should never violate the device limitations 460 * May return a smaller bio when running out of pages, indicated by 461 * *out_of_pages set to 1. 462 */ 463 static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size, 464 unsigned *out_of_pages) 465 { 466 struct crypt_config *cc = io->target->private; 467 struct bio *clone; 468 unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 469 gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM; 470 unsigned i, len; 471 struct page *page; 472 473 clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs); 474 if (!clone) 475 return NULL; 476 477 clone_init(io, clone); 478 *out_of_pages = 0; 479 480 for (i = 0; i < nr_iovecs; i++) { 481 page = mempool_alloc(cc->page_pool, gfp_mask); 482 if (!page) { 483 *out_of_pages = 1; 484 break; 485 } 486 487 /* 488 * if additional pages cannot be allocated without waiting, 489 * return a partially allocated bio, the caller will then try 490 * to allocate additional bios while submitting this partial bio 491 */ 492 if (i == (MIN_BIO_PAGES - 1)) 493 gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; 494 495 len = (size > PAGE_SIZE) ? PAGE_SIZE : size; 496 497 if (!bio_add_page(clone, page, len, 0)) { 498 mempool_free(page, cc->page_pool); 499 break; 500 } 501 502 size -= len; 503 } 504 505 if (!clone->bi_size) { 506 bio_put(clone); 507 return NULL; 508 } 509 510 return clone; 511 } 512 513 static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone) 514 { 515 unsigned int i; 516 struct bio_vec *bv; 517 518 for (i = 0; i < clone->bi_vcnt; i++) { 519 bv = bio_iovec_idx(clone, i); 520 BUG_ON(!bv->bv_page); 521 mempool_free(bv->bv_page, cc->page_pool); 522 bv->bv_page = NULL; 523 } 524 } 525 526 static struct dm_crypt_io *crypt_io_alloc(struct dm_target *ti, 527 struct bio *bio, sector_t sector) 528 { 529 struct crypt_config *cc = ti->private; 530 struct dm_crypt_io *io; 531 532 io = mempool_alloc(cc->io_pool, GFP_NOIO); 533 io->target = ti; 534 io->base_bio = bio; 535 io->sector = sector; 536 io->error = 0; 537 io->base_io = NULL; 538 atomic_set(&io->pending, 0); 539 540 return io; 541 } 542 543 static void crypt_inc_pending(struct dm_crypt_io *io) 544 { 545 atomic_inc(&io->pending); 546 } 547 548 /* 549 * One of the bios was finished. Check for completion of 550 * the whole request and correctly clean up the buffer. 551 * If base_io is set, wait for the last fragment to complete. 552 */ 553 static void crypt_dec_pending(struct dm_crypt_io *io) 554 { 555 struct crypt_config *cc = io->target->private; 556 557 if (!atomic_dec_and_test(&io->pending)) 558 return; 559 560 if (likely(!io->base_io)) 561 bio_endio(io->base_bio, io->error); 562 else { 563 if (io->error && !io->base_io->error) 564 io->base_io->error = io->error; 565 crypt_dec_pending(io->base_io); 566 } 567 568 mempool_free(io, cc->io_pool); 569 } 570 571 /* 572 * kcryptd/kcryptd_io: 573 * 574 * Needed because it would be very unwise to do decryption in an 575 * interrupt context. 576 * 577 * kcryptd performs the actual encryption or decryption. 578 * 579 * kcryptd_io performs the IO submission. 580 * 581 * They must be separated as otherwise the final stages could be 582 * starved by new requests which can block in the first stages due 583 * to memory allocation. 584 */ 585 static void crypt_endio(struct bio *clone, int error) 586 { 587 struct dm_crypt_io *io = clone->bi_private; 588 struct crypt_config *cc = io->target->private; 589 unsigned rw = bio_data_dir(clone); 590 591 if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error)) 592 error = -EIO; 593 594 /* 595 * free the processed pages 596 */ 597 if (rw == WRITE) 598 crypt_free_buffer_pages(cc, clone); 599 600 bio_put(clone); 601 602 if (rw == READ && !error) { 603 kcryptd_queue_crypt(io); 604 return; 605 } 606 607 if (unlikely(error)) 608 io->error = error; 609 610 crypt_dec_pending(io); 611 } 612 613 static void clone_init(struct dm_crypt_io *io, struct bio *clone) 614 { 615 struct crypt_config *cc = io->target->private; 616 617 clone->bi_private = io; 618 clone->bi_end_io = crypt_endio; 619 clone->bi_bdev = cc->dev->bdev; 620 clone->bi_rw = io->base_bio->bi_rw; 621 clone->bi_destructor = dm_crypt_bio_destructor; 622 } 623 624 static void kcryptd_io_read(struct dm_crypt_io *io) 625 { 626 struct crypt_config *cc = io->target->private; 627 struct bio *base_bio = io->base_bio; 628 struct bio *clone; 629 630 crypt_inc_pending(io); 631 632 /* 633 * The block layer might modify the bvec array, so always 634 * copy the required bvecs because we need the original 635 * one in order to decrypt the whole bio data *afterwards*. 636 */ 637 clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs); 638 if (unlikely(!clone)) { 639 io->error = -ENOMEM; 640 crypt_dec_pending(io); 641 return; 642 } 643 644 clone_init(io, clone); 645 clone->bi_idx = 0; 646 clone->bi_vcnt = bio_segments(base_bio); 647 clone->bi_size = base_bio->bi_size; 648 clone->bi_sector = cc->start + io->sector; 649 memcpy(clone->bi_io_vec, bio_iovec(base_bio), 650 sizeof(struct bio_vec) * clone->bi_vcnt); 651 652 generic_make_request(clone); 653 } 654 655 static void kcryptd_io_write(struct dm_crypt_io *io) 656 { 657 struct bio *clone = io->ctx.bio_out; 658 generic_make_request(clone); 659 } 660 661 static void kcryptd_io(struct work_struct *work) 662 { 663 struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); 664 665 if (bio_data_dir(io->base_bio) == READ) 666 kcryptd_io_read(io); 667 else 668 kcryptd_io_write(io); 669 } 670 671 static void kcryptd_queue_io(struct dm_crypt_io *io) 672 { 673 struct crypt_config *cc = io->target->private; 674 675 INIT_WORK(&io->work, kcryptd_io); 676 queue_work(cc->io_queue, &io->work); 677 } 678 679 static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, 680 int error, int async) 681 { 682 struct bio *clone = io->ctx.bio_out; 683 struct crypt_config *cc = io->target->private; 684 685 if (unlikely(error < 0)) { 686 crypt_free_buffer_pages(cc, clone); 687 bio_put(clone); 688 io->error = -EIO; 689 crypt_dec_pending(io); 690 return; 691 } 692 693 /* crypt_convert should have filled the clone bio */ 694 BUG_ON(io->ctx.idx_out < clone->bi_vcnt); 695 696 clone->bi_sector = cc->start + io->sector; 697 698 if (async) 699 kcryptd_queue_io(io); 700 else 701 generic_make_request(clone); 702 } 703 704 static void kcryptd_crypt_write_convert(struct dm_crypt_io *io) 705 { 706 struct crypt_config *cc = io->target->private; 707 struct bio *clone; 708 struct dm_crypt_io *new_io; 709 int crypt_finished; 710 unsigned out_of_pages = 0; 711 unsigned remaining = io->base_bio->bi_size; 712 sector_t sector = io->sector; 713 int r; 714 715 /* 716 * Prevent io from disappearing until this function completes. 717 */ 718 crypt_inc_pending(io); 719 crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector); 720 721 /* 722 * The allocated buffers can be smaller than the whole bio, 723 * so repeat the whole process until all the data can be handled. 724 */ 725 while (remaining) { 726 clone = crypt_alloc_buffer(io, remaining, &out_of_pages); 727 if (unlikely(!clone)) { 728 io->error = -ENOMEM; 729 break; 730 } 731 732 io->ctx.bio_out = clone; 733 io->ctx.idx_out = 0; 734 735 remaining -= clone->bi_size; 736 sector += bio_sectors(clone); 737 738 crypt_inc_pending(io); 739 r = crypt_convert(cc, &io->ctx); 740 crypt_finished = atomic_dec_and_test(&io->ctx.pending); 741 742 /* Encryption was already finished, submit io now */ 743 if (crypt_finished) { 744 kcryptd_crypt_write_io_submit(io, r, 0); 745 746 /* 747 * If there was an error, do not try next fragments. 748 * For async, error is processed in async handler. 749 */ 750 if (unlikely(r < 0)) 751 break; 752 753 io->sector = sector; 754 } 755 756 /* 757 * Out of memory -> run queues 758 * But don't wait if split was due to the io size restriction 759 */ 760 if (unlikely(out_of_pages)) 761 congestion_wait(WRITE, HZ/100); 762 763 /* 764 * With async crypto it is unsafe to share the crypto context 765 * between fragments, so switch to a new dm_crypt_io structure. 766 */ 767 if (unlikely(!crypt_finished && remaining)) { 768 new_io = crypt_io_alloc(io->target, io->base_bio, 769 sector); 770 crypt_inc_pending(new_io); 771 crypt_convert_init(cc, &new_io->ctx, NULL, 772 io->base_bio, sector); 773 new_io->ctx.idx_in = io->ctx.idx_in; 774 new_io->ctx.offset_in = io->ctx.offset_in; 775 776 /* 777 * Fragments after the first use the base_io 778 * pending count. 779 */ 780 if (!io->base_io) 781 new_io->base_io = io; 782 else { 783 new_io->base_io = io->base_io; 784 crypt_inc_pending(io->base_io); 785 crypt_dec_pending(io); 786 } 787 788 io = new_io; 789 } 790 } 791 792 crypt_dec_pending(io); 793 } 794 795 static void kcryptd_crypt_read_done(struct dm_crypt_io *io, int error) 796 { 797 if (unlikely(error < 0)) 798 io->error = -EIO; 799 800 crypt_dec_pending(io); 801 } 802 803 static void kcryptd_crypt_read_convert(struct dm_crypt_io *io) 804 { 805 struct crypt_config *cc = io->target->private; 806 int r = 0; 807 808 crypt_inc_pending(io); 809 810 crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio, 811 io->sector); 812 813 r = crypt_convert(cc, &io->ctx); 814 815 if (atomic_dec_and_test(&io->ctx.pending)) 816 kcryptd_crypt_read_done(io, r); 817 818 crypt_dec_pending(io); 819 } 820 821 static void kcryptd_async_done(struct crypto_async_request *async_req, 822 int error) 823 { 824 struct convert_context *ctx = async_req->data; 825 struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx); 826 struct crypt_config *cc = io->target->private; 827 828 if (error == -EINPROGRESS) { 829 complete(&ctx->restart); 830 return; 831 } 832 833 mempool_free(ablkcipher_request_cast(async_req), cc->req_pool); 834 835 if (!atomic_dec_and_test(&ctx->pending)) 836 return; 837 838 if (bio_data_dir(io->base_bio) == READ) 839 kcryptd_crypt_read_done(io, error); 840 else 841 kcryptd_crypt_write_io_submit(io, error, 1); 842 } 843 844 static void kcryptd_crypt(struct work_struct *work) 845 { 846 struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); 847 848 if (bio_data_dir(io->base_bio) == READ) 849 kcryptd_crypt_read_convert(io); 850 else 851 kcryptd_crypt_write_convert(io); 852 } 853 854 static void kcryptd_queue_crypt(struct dm_crypt_io *io) 855 { 856 struct crypt_config *cc = io->target->private; 857 858 INIT_WORK(&io->work, kcryptd_crypt); 859 queue_work(cc->crypt_queue, &io->work); 860 } 861 862 /* 863 * Decode key from its hex representation 864 */ 865 static int crypt_decode_key(u8 *key, char *hex, unsigned int size) 866 { 867 char buffer[3]; 868 char *endp; 869 unsigned int i; 870 871 buffer[2] = '\0'; 872 873 for (i = 0; i < size; i++) { 874 buffer[0] = *hex++; 875 buffer[1] = *hex++; 876 877 key[i] = (u8)simple_strtoul(buffer, &endp, 16); 878 879 if (endp != &buffer[2]) 880 return -EINVAL; 881 } 882 883 if (*hex != '\0') 884 return -EINVAL; 885 886 return 0; 887 } 888 889 /* 890 * Encode key into its hex representation 891 */ 892 static void crypt_encode_key(char *hex, u8 *key, unsigned int size) 893 { 894 unsigned int i; 895 896 for (i = 0; i < size; i++) { 897 sprintf(hex, "%02x", *key); 898 hex += 2; 899 key++; 900 } 901 } 902 903 static int crypt_set_key(struct crypt_config *cc, char *key) 904 { 905 unsigned key_size = strlen(key) >> 1; 906 907 if (cc->key_size && cc->key_size != key_size) 908 return -EINVAL; 909 910 cc->key_size = key_size; /* initial settings */ 911 912 if ((!key_size && strcmp(key, "-")) || 913 (key_size && crypt_decode_key(cc->key, key, key_size) < 0)) 914 return -EINVAL; 915 916 set_bit(DM_CRYPT_KEY_VALID, &cc->flags); 917 918 return 0; 919 } 920 921 static int crypt_wipe_key(struct crypt_config *cc) 922 { 923 clear_bit(DM_CRYPT_KEY_VALID, &cc->flags); 924 memset(&cc->key, 0, cc->key_size * sizeof(u8)); 925 return 0; 926 } 927 928 /* 929 * Construct an encryption mapping: 930 * <cipher> <key> <iv_offset> <dev_path> <start> 931 */ 932 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) 933 { 934 struct crypt_config *cc; 935 struct crypto_ablkcipher *tfm; 936 char *tmp; 937 char *cipher; 938 char *chainmode; 939 char *ivmode; 940 char *ivopts; 941 unsigned int key_size; 942 unsigned long long tmpll; 943 944 if (argc != 5) { 945 ti->error = "Not enough arguments"; 946 return -EINVAL; 947 } 948 949 tmp = argv[0]; 950 cipher = strsep(&tmp, "-"); 951 chainmode = strsep(&tmp, "-"); 952 ivopts = strsep(&tmp, "-"); 953 ivmode = strsep(&ivopts, ":"); 954 955 if (tmp) 956 DMWARN("Unexpected additional cipher options"); 957 958 key_size = strlen(argv[1]) >> 1; 959 960 cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL); 961 if (cc == NULL) { 962 ti->error = 963 "Cannot allocate transparent encryption context"; 964 return -ENOMEM; 965 } 966 967 if (crypt_set_key(cc, argv[1])) { 968 ti->error = "Error decoding key"; 969 goto bad_cipher; 970 } 971 972 /* Compatiblity mode for old dm-crypt cipher strings */ 973 if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) { 974 chainmode = "cbc"; 975 ivmode = "plain"; 976 } 977 978 if (strcmp(chainmode, "ecb") && !ivmode) { 979 ti->error = "This chaining mode requires an IV mechanism"; 980 goto bad_cipher; 981 } 982 983 if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", 984 chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) { 985 ti->error = "Chain mode + cipher name is too long"; 986 goto bad_cipher; 987 } 988 989 tfm = crypto_alloc_ablkcipher(cc->cipher, 0, 0); 990 if (IS_ERR(tfm)) { 991 ti->error = "Error allocating crypto tfm"; 992 goto bad_cipher; 993 } 994 995 strcpy(cc->cipher, cipher); 996 strcpy(cc->chainmode, chainmode); 997 cc->tfm = tfm; 998 999 /* 1000 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi". 1001 * See comments at iv code 1002 */ 1003 1004 if (ivmode == NULL) 1005 cc->iv_gen_ops = NULL; 1006 else if (strcmp(ivmode, "plain") == 0) 1007 cc->iv_gen_ops = &crypt_iv_plain_ops; 1008 else if (strcmp(ivmode, "essiv") == 0) 1009 cc->iv_gen_ops = &crypt_iv_essiv_ops; 1010 else if (strcmp(ivmode, "benbi") == 0) 1011 cc->iv_gen_ops = &crypt_iv_benbi_ops; 1012 else if (strcmp(ivmode, "null") == 0) 1013 cc->iv_gen_ops = &crypt_iv_null_ops; 1014 else { 1015 ti->error = "Invalid IV mode"; 1016 goto bad_ivmode; 1017 } 1018 1019 if (cc->iv_gen_ops && cc->iv_gen_ops->ctr && 1020 cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) 1021 goto bad_ivmode; 1022 1023 cc->iv_size = crypto_ablkcipher_ivsize(tfm); 1024 if (cc->iv_size) 1025 /* at least a 64 bit sector number should fit in our buffer */ 1026 cc->iv_size = max(cc->iv_size, 1027 (unsigned int)(sizeof(u64) / sizeof(u8))); 1028 else { 1029 if (cc->iv_gen_ops) { 1030 DMWARN("Selected cipher does not support IVs"); 1031 if (cc->iv_gen_ops->dtr) 1032 cc->iv_gen_ops->dtr(cc); 1033 cc->iv_gen_ops = NULL; 1034 } 1035 } 1036 1037 cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool); 1038 if (!cc->io_pool) { 1039 ti->error = "Cannot allocate crypt io mempool"; 1040 goto bad_slab_pool; 1041 } 1042 1043 cc->dmreq_start = sizeof(struct ablkcipher_request); 1044 cc->dmreq_start += crypto_ablkcipher_reqsize(tfm); 1045 cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment()); 1046 cc->dmreq_start += crypto_ablkcipher_alignmask(tfm) & 1047 ~(crypto_tfm_ctx_alignment() - 1); 1048 1049 cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start + 1050 sizeof(struct dm_crypt_request) + cc->iv_size); 1051 if (!cc->req_pool) { 1052 ti->error = "Cannot allocate crypt request mempool"; 1053 goto bad_req_pool; 1054 } 1055 cc->req = NULL; 1056 1057 cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0); 1058 if (!cc->page_pool) { 1059 ti->error = "Cannot allocate page mempool"; 1060 goto bad_page_pool; 1061 } 1062 1063 cc->bs = bioset_create(MIN_IOS, MIN_IOS); 1064 if (!cc->bs) { 1065 ti->error = "Cannot allocate crypt bioset"; 1066 goto bad_bs; 1067 } 1068 1069 if (crypto_ablkcipher_setkey(tfm, cc->key, key_size) < 0) { 1070 ti->error = "Error setting key"; 1071 goto bad_device; 1072 } 1073 1074 if (sscanf(argv[2], "%llu", &tmpll) != 1) { 1075 ti->error = "Invalid iv_offset sector"; 1076 goto bad_device; 1077 } 1078 cc->iv_offset = tmpll; 1079 1080 if (sscanf(argv[4], "%llu", &tmpll) != 1) { 1081 ti->error = "Invalid device sector"; 1082 goto bad_device; 1083 } 1084 cc->start = tmpll; 1085 1086 if (dm_get_device(ti, argv[3], cc->start, ti->len, 1087 dm_table_get_mode(ti->table), &cc->dev)) { 1088 ti->error = "Device lookup failed"; 1089 goto bad_device; 1090 } 1091 1092 if (ivmode && cc->iv_gen_ops) { 1093 if (ivopts) 1094 *(ivopts - 1) = ':'; 1095 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL); 1096 if (!cc->iv_mode) { 1097 ti->error = "Error kmallocing iv_mode string"; 1098 goto bad_ivmode_string; 1099 } 1100 strcpy(cc->iv_mode, ivmode); 1101 } else 1102 cc->iv_mode = NULL; 1103 1104 cc->io_queue = create_singlethread_workqueue("kcryptd_io"); 1105 if (!cc->io_queue) { 1106 ti->error = "Couldn't create kcryptd io queue"; 1107 goto bad_io_queue; 1108 } 1109 1110 cc->crypt_queue = create_singlethread_workqueue("kcryptd"); 1111 if (!cc->crypt_queue) { 1112 ti->error = "Couldn't create kcryptd queue"; 1113 goto bad_crypt_queue; 1114 } 1115 1116 ti->private = cc; 1117 return 0; 1118 1119 bad_crypt_queue: 1120 destroy_workqueue(cc->io_queue); 1121 bad_io_queue: 1122 kfree(cc->iv_mode); 1123 bad_ivmode_string: 1124 dm_put_device(ti, cc->dev); 1125 bad_device: 1126 bioset_free(cc->bs); 1127 bad_bs: 1128 mempool_destroy(cc->page_pool); 1129 bad_page_pool: 1130 mempool_destroy(cc->req_pool); 1131 bad_req_pool: 1132 mempool_destroy(cc->io_pool); 1133 bad_slab_pool: 1134 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 1135 cc->iv_gen_ops->dtr(cc); 1136 bad_ivmode: 1137 crypto_free_ablkcipher(tfm); 1138 bad_cipher: 1139 /* Must zero key material before freeing */ 1140 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 1141 kfree(cc); 1142 return -EINVAL; 1143 } 1144 1145 static void crypt_dtr(struct dm_target *ti) 1146 { 1147 struct crypt_config *cc = (struct crypt_config *) ti->private; 1148 1149 destroy_workqueue(cc->io_queue); 1150 destroy_workqueue(cc->crypt_queue); 1151 1152 if (cc->req) 1153 mempool_free(cc->req, cc->req_pool); 1154 1155 bioset_free(cc->bs); 1156 mempool_destroy(cc->page_pool); 1157 mempool_destroy(cc->req_pool); 1158 mempool_destroy(cc->io_pool); 1159 1160 kfree(cc->iv_mode); 1161 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 1162 cc->iv_gen_ops->dtr(cc); 1163 crypto_free_ablkcipher(cc->tfm); 1164 dm_put_device(ti, cc->dev); 1165 1166 /* Must zero key material before freeing */ 1167 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 1168 kfree(cc); 1169 } 1170 1171 static int crypt_map(struct dm_target *ti, struct bio *bio, 1172 union map_info *map_context) 1173 { 1174 struct dm_crypt_io *io; 1175 1176 io = crypt_io_alloc(ti, bio, bio->bi_sector - ti->begin); 1177 1178 if (bio_data_dir(io->base_bio) == READ) 1179 kcryptd_queue_io(io); 1180 else 1181 kcryptd_queue_crypt(io); 1182 1183 return DM_MAPIO_SUBMITTED; 1184 } 1185 1186 static int crypt_status(struct dm_target *ti, status_type_t type, 1187 char *result, unsigned int maxlen) 1188 { 1189 struct crypt_config *cc = (struct crypt_config *) ti->private; 1190 unsigned int sz = 0; 1191 1192 switch (type) { 1193 case STATUSTYPE_INFO: 1194 result[0] = '\0'; 1195 break; 1196 1197 case STATUSTYPE_TABLE: 1198 if (cc->iv_mode) 1199 DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode, 1200 cc->iv_mode); 1201 else 1202 DMEMIT("%s-%s ", cc->cipher, cc->chainmode); 1203 1204 if (cc->key_size > 0) { 1205 if ((maxlen - sz) < ((cc->key_size << 1) + 1)) 1206 return -ENOMEM; 1207 1208 crypt_encode_key(result + sz, cc->key, cc->key_size); 1209 sz += cc->key_size << 1; 1210 } else { 1211 if (sz >= maxlen) 1212 return -ENOMEM; 1213 result[sz++] = '-'; 1214 } 1215 1216 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset, 1217 cc->dev->name, (unsigned long long)cc->start); 1218 break; 1219 } 1220 return 0; 1221 } 1222 1223 static void crypt_postsuspend(struct dm_target *ti) 1224 { 1225 struct crypt_config *cc = ti->private; 1226 1227 set_bit(DM_CRYPT_SUSPENDED, &cc->flags); 1228 } 1229 1230 static int crypt_preresume(struct dm_target *ti) 1231 { 1232 struct crypt_config *cc = ti->private; 1233 1234 if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) { 1235 DMERR("aborting resume - crypt key is not set."); 1236 return -EAGAIN; 1237 } 1238 1239 return 0; 1240 } 1241 1242 static void crypt_resume(struct dm_target *ti) 1243 { 1244 struct crypt_config *cc = ti->private; 1245 1246 clear_bit(DM_CRYPT_SUSPENDED, &cc->flags); 1247 } 1248 1249 /* Message interface 1250 * key set <key> 1251 * key wipe 1252 */ 1253 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv) 1254 { 1255 struct crypt_config *cc = ti->private; 1256 1257 if (argc < 2) 1258 goto error; 1259 1260 if (!strnicmp(argv[0], MESG_STR("key"))) { 1261 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) { 1262 DMWARN("not suspended during key manipulation."); 1263 return -EINVAL; 1264 } 1265 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set"))) 1266 return crypt_set_key(cc, argv[2]); 1267 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe"))) 1268 return crypt_wipe_key(cc); 1269 } 1270 1271 error: 1272 DMWARN("unrecognised message received."); 1273 return -EINVAL; 1274 } 1275 1276 static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 1277 struct bio_vec *biovec, int max_size) 1278 { 1279 struct crypt_config *cc = ti->private; 1280 struct request_queue *q = bdev_get_queue(cc->dev->bdev); 1281 1282 if (!q->merge_bvec_fn) 1283 return max_size; 1284 1285 bvm->bi_bdev = cc->dev->bdev; 1286 bvm->bi_sector = cc->start + bvm->bi_sector - ti->begin; 1287 1288 return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); 1289 } 1290 1291 static struct target_type crypt_target = { 1292 .name = "crypt", 1293 .version= {1, 6, 0}, 1294 .module = THIS_MODULE, 1295 .ctr = crypt_ctr, 1296 .dtr = crypt_dtr, 1297 .map = crypt_map, 1298 .status = crypt_status, 1299 .postsuspend = crypt_postsuspend, 1300 .preresume = crypt_preresume, 1301 .resume = crypt_resume, 1302 .message = crypt_message, 1303 .merge = crypt_merge, 1304 }; 1305 1306 static int __init dm_crypt_init(void) 1307 { 1308 int r; 1309 1310 _crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0); 1311 if (!_crypt_io_pool) 1312 return -ENOMEM; 1313 1314 r = dm_register_target(&crypt_target); 1315 if (r < 0) { 1316 DMERR("register failed %d", r); 1317 kmem_cache_destroy(_crypt_io_pool); 1318 } 1319 1320 return r; 1321 } 1322 1323 static void __exit dm_crypt_exit(void) 1324 { 1325 int r = dm_unregister_target(&crypt_target); 1326 1327 if (r < 0) 1328 DMERR("unregister failed %d", r); 1329 1330 kmem_cache_destroy(_crypt_io_pool); 1331 } 1332 1333 module_init(dm_crypt_init); 1334 module_exit(dm_crypt_exit); 1335 1336 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>"); 1337 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption"); 1338 MODULE_LICENSE("GPL"); 1339