1 /* 2 * Copyright (C) 2003 Christophe Saout <christophe@saout.de> 3 * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org> 4 * Copyright (C) 2006 Red Hat, Inc. All rights reserved. 5 * 6 * This file is released under the GPL. 7 */ 8 9 #include <linux/err.h> 10 #include <linux/module.h> 11 #include <linux/init.h> 12 #include <linux/kernel.h> 13 #include <linux/bio.h> 14 #include <linux/blkdev.h> 15 #include <linux/mempool.h> 16 #include <linux/slab.h> 17 #include <linux/crypto.h> 18 #include <linux/workqueue.h> 19 #include <linux/backing-dev.h> 20 #include <asm/atomic.h> 21 #include <linux/scatterlist.h> 22 #include <asm/page.h> 23 #include <asm/unaligned.h> 24 25 #include "dm.h" 26 27 #define DM_MSG_PREFIX "crypt" 28 #define MESG_STR(x) x, sizeof(x) 29 30 /* 31 * per bio private data 32 */ 33 struct crypt_io { 34 struct dm_target *target; 35 struct bio *base_bio; 36 struct bio *first_clone; 37 struct work_struct work; 38 atomic_t pending; 39 int error; 40 int post_process; 41 }; 42 43 /* 44 * context holding the current state of a multi-part conversion 45 */ 46 struct convert_context { 47 struct bio *bio_in; 48 struct bio *bio_out; 49 unsigned int offset_in; 50 unsigned int offset_out; 51 unsigned int idx_in; 52 unsigned int idx_out; 53 sector_t sector; 54 int write; 55 }; 56 57 struct crypt_config; 58 59 struct crypt_iv_operations { 60 int (*ctr)(struct crypt_config *cc, struct dm_target *ti, 61 const char *opts); 62 void (*dtr)(struct crypt_config *cc); 63 const char *(*status)(struct crypt_config *cc); 64 int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector); 65 }; 66 67 /* 68 * Crypt: maps a linear range of a block device 69 * and encrypts / decrypts at the same time. 70 */ 71 enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID }; 72 struct crypt_config { 73 struct dm_dev *dev; 74 sector_t start; 75 76 /* 77 * pool for per bio private data and 78 * for encryption buffer pages 79 */ 80 mempool_t *io_pool; 81 mempool_t *page_pool; 82 struct bio_set *bs; 83 84 /* 85 * crypto related data 86 */ 87 struct crypt_iv_operations *iv_gen_ops; 88 char *iv_mode; 89 union { 90 struct crypto_cipher *essiv_tfm; 91 int benbi_shift; 92 } iv_gen_private; 93 sector_t iv_offset; 94 unsigned int iv_size; 95 96 char cipher[CRYPTO_MAX_ALG_NAME]; 97 char chainmode[CRYPTO_MAX_ALG_NAME]; 98 struct crypto_blkcipher *tfm; 99 unsigned long flags; 100 unsigned int key_size; 101 u8 key[0]; 102 }; 103 104 #define MIN_IOS 16 105 #define MIN_POOL_PAGES 32 106 #define MIN_BIO_PAGES 8 107 108 static struct kmem_cache *_crypt_io_pool; 109 110 /* 111 * Different IV generation algorithms: 112 * 113 * plain: the initial vector is the 32-bit little-endian version of the sector 114 * number, padded with zeros if neccessary. 115 * 116 * essiv: "encrypted sector|salt initial vector", the sector number is 117 * encrypted with the bulk cipher using a salt as key. The salt 118 * should be derived from the bulk cipher's key via hashing. 119 * 120 * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1 121 * (needed for LRW-32-AES and possible other narrow block modes) 122 * 123 * plumb: unimplemented, see: 124 * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454 125 */ 126 127 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 128 { 129 memset(iv, 0, cc->iv_size); 130 *(u32 *)iv = cpu_to_le32(sector & 0xffffffff); 131 132 return 0; 133 } 134 135 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, 136 const char *opts) 137 { 138 struct crypto_cipher *essiv_tfm; 139 struct crypto_hash *hash_tfm; 140 struct hash_desc desc; 141 struct scatterlist sg; 142 unsigned int saltsize; 143 u8 *salt; 144 int err; 145 146 if (opts == NULL) { 147 ti->error = "Digest algorithm missing for ESSIV mode"; 148 return -EINVAL; 149 } 150 151 /* Hash the cipher key with the given hash algorithm */ 152 hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC); 153 if (IS_ERR(hash_tfm)) { 154 ti->error = "Error initializing ESSIV hash"; 155 return PTR_ERR(hash_tfm); 156 } 157 158 saltsize = crypto_hash_digestsize(hash_tfm); 159 salt = kmalloc(saltsize, GFP_KERNEL); 160 if (salt == NULL) { 161 ti->error = "Error kmallocing salt storage in ESSIV"; 162 crypto_free_hash(hash_tfm); 163 return -ENOMEM; 164 } 165 166 sg_set_buf(&sg, cc->key, cc->key_size); 167 desc.tfm = hash_tfm; 168 desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; 169 err = crypto_hash_digest(&desc, &sg, cc->key_size, salt); 170 crypto_free_hash(hash_tfm); 171 172 if (err) { 173 ti->error = "Error calculating hash in ESSIV"; 174 return err; 175 } 176 177 /* Setup the essiv_tfm with the given salt */ 178 essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC); 179 if (IS_ERR(essiv_tfm)) { 180 ti->error = "Error allocating crypto tfm for ESSIV"; 181 kfree(salt); 182 return PTR_ERR(essiv_tfm); 183 } 184 if (crypto_cipher_blocksize(essiv_tfm) != 185 crypto_blkcipher_ivsize(cc->tfm)) { 186 ti->error = "Block size of ESSIV cipher does " 187 "not match IV size of block cipher"; 188 crypto_free_cipher(essiv_tfm); 189 kfree(salt); 190 return -EINVAL; 191 } 192 err = crypto_cipher_setkey(essiv_tfm, salt, saltsize); 193 if (err) { 194 ti->error = "Failed to set key for ESSIV cipher"; 195 crypto_free_cipher(essiv_tfm); 196 kfree(salt); 197 return err; 198 } 199 kfree(salt); 200 201 cc->iv_gen_private.essiv_tfm = essiv_tfm; 202 return 0; 203 } 204 205 static void crypt_iv_essiv_dtr(struct crypt_config *cc) 206 { 207 crypto_free_cipher(cc->iv_gen_private.essiv_tfm); 208 cc->iv_gen_private.essiv_tfm = NULL; 209 } 210 211 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 212 { 213 memset(iv, 0, cc->iv_size); 214 *(u64 *)iv = cpu_to_le64(sector); 215 crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv); 216 return 0; 217 } 218 219 static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti, 220 const char *opts) 221 { 222 unsigned int bs = crypto_blkcipher_blocksize(cc->tfm); 223 int log = ilog2(bs); 224 225 /* we need to calculate how far we must shift the sector count 226 * to get the cipher block count, we use this shift in _gen */ 227 228 if (1 << log != bs) { 229 ti->error = "cypher blocksize is not a power of 2"; 230 return -EINVAL; 231 } 232 233 if (log > 9) { 234 ti->error = "cypher blocksize is > 512"; 235 return -EINVAL; 236 } 237 238 cc->iv_gen_private.benbi_shift = 9 - log; 239 240 return 0; 241 } 242 243 static void crypt_iv_benbi_dtr(struct crypt_config *cc) 244 { 245 } 246 247 static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 248 { 249 __be64 val; 250 251 memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */ 252 253 val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1); 254 put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64))); 255 256 return 0; 257 } 258 259 static struct crypt_iv_operations crypt_iv_plain_ops = { 260 .generator = crypt_iv_plain_gen 261 }; 262 263 static struct crypt_iv_operations crypt_iv_essiv_ops = { 264 .ctr = crypt_iv_essiv_ctr, 265 .dtr = crypt_iv_essiv_dtr, 266 .generator = crypt_iv_essiv_gen 267 }; 268 269 static struct crypt_iv_operations crypt_iv_benbi_ops = { 270 .ctr = crypt_iv_benbi_ctr, 271 .dtr = crypt_iv_benbi_dtr, 272 .generator = crypt_iv_benbi_gen 273 }; 274 275 static int 276 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out, 277 struct scatterlist *in, unsigned int length, 278 int write, sector_t sector) 279 { 280 u8 iv[cc->iv_size] __attribute__ ((aligned(__alignof__(u64)))); 281 struct blkcipher_desc desc = { 282 .tfm = cc->tfm, 283 .info = iv, 284 .flags = CRYPTO_TFM_REQ_MAY_SLEEP, 285 }; 286 int r; 287 288 if (cc->iv_gen_ops) { 289 r = cc->iv_gen_ops->generator(cc, iv, sector); 290 if (r < 0) 291 return r; 292 293 if (write) 294 r = crypto_blkcipher_encrypt_iv(&desc, out, in, length); 295 else 296 r = crypto_blkcipher_decrypt_iv(&desc, out, in, length); 297 } else { 298 if (write) 299 r = crypto_blkcipher_encrypt(&desc, out, in, length); 300 else 301 r = crypto_blkcipher_decrypt(&desc, out, in, length); 302 } 303 304 return r; 305 } 306 307 static void 308 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx, 309 struct bio *bio_out, struct bio *bio_in, 310 sector_t sector, int write) 311 { 312 ctx->bio_in = bio_in; 313 ctx->bio_out = bio_out; 314 ctx->offset_in = 0; 315 ctx->offset_out = 0; 316 ctx->idx_in = bio_in ? bio_in->bi_idx : 0; 317 ctx->idx_out = bio_out ? bio_out->bi_idx : 0; 318 ctx->sector = sector + cc->iv_offset; 319 ctx->write = write; 320 } 321 322 /* 323 * Encrypt / decrypt data from one bio to another one (can be the same one) 324 */ 325 static int crypt_convert(struct crypt_config *cc, 326 struct convert_context *ctx) 327 { 328 int r = 0; 329 330 while(ctx->idx_in < ctx->bio_in->bi_vcnt && 331 ctx->idx_out < ctx->bio_out->bi_vcnt) { 332 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in); 333 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out); 334 struct scatterlist sg_in = { 335 .page = bv_in->bv_page, 336 .offset = bv_in->bv_offset + ctx->offset_in, 337 .length = 1 << SECTOR_SHIFT 338 }; 339 struct scatterlist sg_out = { 340 .page = bv_out->bv_page, 341 .offset = bv_out->bv_offset + ctx->offset_out, 342 .length = 1 << SECTOR_SHIFT 343 }; 344 345 ctx->offset_in += sg_in.length; 346 if (ctx->offset_in >= bv_in->bv_len) { 347 ctx->offset_in = 0; 348 ctx->idx_in++; 349 } 350 351 ctx->offset_out += sg_out.length; 352 if (ctx->offset_out >= bv_out->bv_len) { 353 ctx->offset_out = 0; 354 ctx->idx_out++; 355 } 356 357 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length, 358 ctx->write, ctx->sector); 359 if (r < 0) 360 break; 361 362 ctx->sector++; 363 } 364 365 return r; 366 } 367 368 static void dm_crypt_bio_destructor(struct bio *bio) 369 { 370 struct crypt_io *io = bio->bi_private; 371 struct crypt_config *cc = io->target->private; 372 373 bio_free(bio, cc->bs); 374 } 375 376 /* 377 * Generate a new unfragmented bio with the given size 378 * This should never violate the device limitations 379 * May return a smaller bio when running out of pages 380 */ 381 static struct bio * 382 crypt_alloc_buffer(struct crypt_config *cc, unsigned int size, 383 struct bio *base_bio, unsigned int *bio_vec_idx) 384 { 385 struct bio *clone; 386 unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 387 gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM; 388 unsigned int i; 389 390 if (base_bio) { 391 clone = bio_alloc_bioset(GFP_NOIO, base_bio->bi_max_vecs, cc->bs); 392 __bio_clone(clone, base_bio); 393 } else 394 clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs); 395 396 if (!clone) 397 return NULL; 398 399 clone->bi_destructor = dm_crypt_bio_destructor; 400 401 /* if the last bio was not complete, continue where that one ended */ 402 clone->bi_idx = *bio_vec_idx; 403 clone->bi_vcnt = *bio_vec_idx; 404 clone->bi_size = 0; 405 clone->bi_flags &= ~(1 << BIO_SEG_VALID); 406 407 /* clone->bi_idx pages have already been allocated */ 408 size -= clone->bi_idx * PAGE_SIZE; 409 410 for (i = clone->bi_idx; i < nr_iovecs; i++) { 411 struct bio_vec *bv = bio_iovec_idx(clone, i); 412 413 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask); 414 if (!bv->bv_page) 415 break; 416 417 /* 418 * if additional pages cannot be allocated without waiting, 419 * return a partially allocated bio, the caller will then try 420 * to allocate additional bios while submitting this partial bio 421 */ 422 if ((i - clone->bi_idx) == (MIN_BIO_PAGES - 1)) 423 gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; 424 425 bv->bv_offset = 0; 426 if (size > PAGE_SIZE) 427 bv->bv_len = PAGE_SIZE; 428 else 429 bv->bv_len = size; 430 431 clone->bi_size += bv->bv_len; 432 clone->bi_vcnt++; 433 size -= bv->bv_len; 434 } 435 436 if (!clone->bi_size) { 437 bio_put(clone); 438 return NULL; 439 } 440 441 /* 442 * Remember the last bio_vec allocated to be able 443 * to correctly continue after the splitting. 444 */ 445 *bio_vec_idx = clone->bi_vcnt; 446 447 return clone; 448 } 449 450 static void crypt_free_buffer_pages(struct crypt_config *cc, 451 struct bio *clone, unsigned int bytes) 452 { 453 unsigned int i, start, end; 454 struct bio_vec *bv; 455 456 /* 457 * This is ugly, but Jens Axboe thinks that using bi_idx in the 458 * endio function is too dangerous at the moment, so I calculate the 459 * correct position using bi_vcnt and bi_size. 460 * The bv_offset and bv_len fields might already be modified but we 461 * know that we always allocated whole pages. 462 * A fix to the bi_idx issue in the kernel is in the works, so 463 * we will hopefully be able to revert to the cleaner solution soon. 464 */ 465 i = clone->bi_vcnt - 1; 466 bv = bio_iovec_idx(clone, i); 467 end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - clone->bi_size; 468 start = end - bytes; 469 470 start >>= PAGE_SHIFT; 471 if (!clone->bi_size) 472 end = clone->bi_vcnt; 473 else 474 end >>= PAGE_SHIFT; 475 476 for (i = start; i < end; i++) { 477 bv = bio_iovec_idx(clone, i); 478 BUG_ON(!bv->bv_page); 479 mempool_free(bv->bv_page, cc->page_pool); 480 bv->bv_page = NULL; 481 } 482 } 483 484 /* 485 * One of the bios was finished. Check for completion of 486 * the whole request and correctly clean up the buffer. 487 */ 488 static void dec_pending(struct crypt_io *io, int error) 489 { 490 struct crypt_config *cc = (struct crypt_config *) io->target->private; 491 492 if (error < 0) 493 io->error = error; 494 495 if (!atomic_dec_and_test(&io->pending)) 496 return; 497 498 if (io->first_clone) 499 bio_put(io->first_clone); 500 501 bio_endio(io->base_bio, io->base_bio->bi_size, io->error); 502 503 mempool_free(io, cc->io_pool); 504 } 505 506 /* 507 * kcryptd: 508 * 509 * Needed because it would be very unwise to do decryption in an 510 * interrupt context. 511 */ 512 static struct workqueue_struct *_kcryptd_workqueue; 513 static void kcryptd_do_work(struct work_struct *work); 514 515 static void kcryptd_queue_io(struct crypt_io *io) 516 { 517 INIT_WORK(&io->work, kcryptd_do_work); 518 queue_work(_kcryptd_workqueue, &io->work); 519 } 520 521 static int crypt_endio(struct bio *clone, unsigned int done, int error) 522 { 523 struct crypt_io *io = clone->bi_private; 524 struct crypt_config *cc = io->target->private; 525 unsigned read_io = bio_data_dir(clone) == READ; 526 527 /* 528 * free the processed pages, even if 529 * it's only a partially completed write 530 */ 531 if (!read_io) 532 crypt_free_buffer_pages(cc, clone, done); 533 534 /* keep going - not finished yet */ 535 if (unlikely(clone->bi_size)) 536 return 1; 537 538 if (!read_io) 539 goto out; 540 541 if (unlikely(!bio_flagged(clone, BIO_UPTODATE))) { 542 error = -EIO; 543 goto out; 544 } 545 546 bio_put(clone); 547 io->post_process = 1; 548 kcryptd_queue_io(io); 549 return 0; 550 551 out: 552 bio_put(clone); 553 dec_pending(io, error); 554 return error; 555 } 556 557 static void clone_init(struct crypt_io *io, struct bio *clone) 558 { 559 struct crypt_config *cc = io->target->private; 560 561 clone->bi_private = io; 562 clone->bi_end_io = crypt_endio; 563 clone->bi_bdev = cc->dev->bdev; 564 clone->bi_rw = io->base_bio->bi_rw; 565 } 566 567 static void process_read(struct crypt_io *io) 568 { 569 struct crypt_config *cc = io->target->private; 570 struct bio *base_bio = io->base_bio; 571 struct bio *clone; 572 sector_t sector = base_bio->bi_sector - io->target->begin; 573 574 atomic_inc(&io->pending); 575 576 /* 577 * The block layer might modify the bvec array, so always 578 * copy the required bvecs because we need the original 579 * one in order to decrypt the whole bio data *afterwards*. 580 */ 581 clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs); 582 if (unlikely(!clone)) { 583 dec_pending(io, -ENOMEM); 584 return; 585 } 586 587 clone_init(io, clone); 588 clone->bi_destructor = dm_crypt_bio_destructor; 589 clone->bi_idx = 0; 590 clone->bi_vcnt = bio_segments(base_bio); 591 clone->bi_size = base_bio->bi_size; 592 clone->bi_sector = cc->start + sector; 593 memcpy(clone->bi_io_vec, bio_iovec(base_bio), 594 sizeof(struct bio_vec) * clone->bi_vcnt); 595 596 generic_make_request(clone); 597 } 598 599 static void process_write(struct crypt_io *io) 600 { 601 struct crypt_config *cc = io->target->private; 602 struct bio *base_bio = io->base_bio; 603 struct bio *clone; 604 struct convert_context ctx; 605 unsigned remaining = base_bio->bi_size; 606 sector_t sector = base_bio->bi_sector - io->target->begin; 607 unsigned bvec_idx = 0; 608 609 atomic_inc(&io->pending); 610 611 crypt_convert_init(cc, &ctx, NULL, base_bio, sector, 1); 612 613 /* 614 * The allocated buffers can be smaller than the whole bio, 615 * so repeat the whole process until all the data can be handled. 616 */ 617 while (remaining) { 618 clone = crypt_alloc_buffer(cc, base_bio->bi_size, 619 io->first_clone, &bvec_idx); 620 if (unlikely(!clone)) { 621 dec_pending(io, -ENOMEM); 622 return; 623 } 624 625 ctx.bio_out = clone; 626 627 if (unlikely(crypt_convert(cc, &ctx) < 0)) { 628 crypt_free_buffer_pages(cc, clone, clone->bi_size); 629 bio_put(clone); 630 dec_pending(io, -EIO); 631 return; 632 } 633 634 clone_init(io, clone); 635 clone->bi_sector = cc->start + sector; 636 637 if (!io->first_clone) { 638 /* 639 * hold a reference to the first clone, because it 640 * holds the bio_vec array and that can't be freed 641 * before all other clones are released 642 */ 643 bio_get(clone); 644 io->first_clone = clone; 645 } 646 647 remaining -= clone->bi_size; 648 sector += bio_sectors(clone); 649 650 /* prevent bio_put of first_clone */ 651 if (remaining) 652 atomic_inc(&io->pending); 653 654 generic_make_request(clone); 655 656 /* out of memory -> run queues */ 657 if (remaining) 658 congestion_wait(bio_data_dir(clone), HZ/100); 659 } 660 } 661 662 static void process_read_endio(struct crypt_io *io) 663 { 664 struct crypt_config *cc = io->target->private; 665 struct convert_context ctx; 666 667 crypt_convert_init(cc, &ctx, io->base_bio, io->base_bio, 668 io->base_bio->bi_sector - io->target->begin, 0); 669 670 dec_pending(io, crypt_convert(cc, &ctx)); 671 } 672 673 static void kcryptd_do_work(struct work_struct *work) 674 { 675 struct crypt_io *io = container_of(work, struct crypt_io, work); 676 677 if (io->post_process) 678 process_read_endio(io); 679 else if (bio_data_dir(io->base_bio) == READ) 680 process_read(io); 681 else 682 process_write(io); 683 } 684 685 /* 686 * Decode key from its hex representation 687 */ 688 static int crypt_decode_key(u8 *key, char *hex, unsigned int size) 689 { 690 char buffer[3]; 691 char *endp; 692 unsigned int i; 693 694 buffer[2] = '\0'; 695 696 for (i = 0; i < size; i++) { 697 buffer[0] = *hex++; 698 buffer[1] = *hex++; 699 700 key[i] = (u8)simple_strtoul(buffer, &endp, 16); 701 702 if (endp != &buffer[2]) 703 return -EINVAL; 704 } 705 706 if (*hex != '\0') 707 return -EINVAL; 708 709 return 0; 710 } 711 712 /* 713 * Encode key into its hex representation 714 */ 715 static void crypt_encode_key(char *hex, u8 *key, unsigned int size) 716 { 717 unsigned int i; 718 719 for (i = 0; i < size; i++) { 720 sprintf(hex, "%02x", *key); 721 hex += 2; 722 key++; 723 } 724 } 725 726 static int crypt_set_key(struct crypt_config *cc, char *key) 727 { 728 unsigned key_size = strlen(key) >> 1; 729 730 if (cc->key_size && cc->key_size != key_size) 731 return -EINVAL; 732 733 cc->key_size = key_size; /* initial settings */ 734 735 if ((!key_size && strcmp(key, "-")) || 736 (key_size && crypt_decode_key(cc->key, key, key_size) < 0)) 737 return -EINVAL; 738 739 set_bit(DM_CRYPT_KEY_VALID, &cc->flags); 740 741 return 0; 742 } 743 744 static int crypt_wipe_key(struct crypt_config *cc) 745 { 746 clear_bit(DM_CRYPT_KEY_VALID, &cc->flags); 747 memset(&cc->key, 0, cc->key_size * sizeof(u8)); 748 return 0; 749 } 750 751 /* 752 * Construct an encryption mapping: 753 * <cipher> <key> <iv_offset> <dev_path> <start> 754 */ 755 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) 756 { 757 struct crypt_config *cc; 758 struct crypto_blkcipher *tfm; 759 char *tmp; 760 char *cipher; 761 char *chainmode; 762 char *ivmode; 763 char *ivopts; 764 unsigned int key_size; 765 unsigned long long tmpll; 766 767 if (argc != 5) { 768 ti->error = "Not enough arguments"; 769 return -EINVAL; 770 } 771 772 tmp = argv[0]; 773 cipher = strsep(&tmp, "-"); 774 chainmode = strsep(&tmp, "-"); 775 ivopts = strsep(&tmp, "-"); 776 ivmode = strsep(&ivopts, ":"); 777 778 if (tmp) 779 DMWARN("Unexpected additional cipher options"); 780 781 key_size = strlen(argv[1]) >> 1; 782 783 cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL); 784 if (cc == NULL) { 785 ti->error = 786 "Cannot allocate transparent encryption context"; 787 return -ENOMEM; 788 } 789 790 if (crypt_set_key(cc, argv[1])) { 791 ti->error = "Error decoding key"; 792 goto bad1; 793 } 794 795 /* Compatiblity mode for old dm-crypt cipher strings */ 796 if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) { 797 chainmode = "cbc"; 798 ivmode = "plain"; 799 } 800 801 if (strcmp(chainmode, "ecb") && !ivmode) { 802 ti->error = "This chaining mode requires an IV mechanism"; 803 goto bad1; 804 } 805 806 if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)", chainmode, 807 cipher) >= CRYPTO_MAX_ALG_NAME) { 808 ti->error = "Chain mode + cipher name is too long"; 809 goto bad1; 810 } 811 812 tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC); 813 if (IS_ERR(tfm)) { 814 ti->error = "Error allocating crypto tfm"; 815 goto bad1; 816 } 817 818 strcpy(cc->cipher, cipher); 819 strcpy(cc->chainmode, chainmode); 820 cc->tfm = tfm; 821 822 /* 823 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi". 824 * See comments at iv code 825 */ 826 827 if (ivmode == NULL) 828 cc->iv_gen_ops = NULL; 829 else if (strcmp(ivmode, "plain") == 0) 830 cc->iv_gen_ops = &crypt_iv_plain_ops; 831 else if (strcmp(ivmode, "essiv") == 0) 832 cc->iv_gen_ops = &crypt_iv_essiv_ops; 833 else if (strcmp(ivmode, "benbi") == 0) 834 cc->iv_gen_ops = &crypt_iv_benbi_ops; 835 else { 836 ti->error = "Invalid IV mode"; 837 goto bad2; 838 } 839 840 if (cc->iv_gen_ops && cc->iv_gen_ops->ctr && 841 cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) 842 goto bad2; 843 844 cc->iv_size = crypto_blkcipher_ivsize(tfm); 845 if (cc->iv_size) 846 /* at least a 64 bit sector number should fit in our buffer */ 847 cc->iv_size = max(cc->iv_size, 848 (unsigned int)(sizeof(u64) / sizeof(u8))); 849 else { 850 if (cc->iv_gen_ops) { 851 DMWARN("Selected cipher does not support IVs"); 852 if (cc->iv_gen_ops->dtr) 853 cc->iv_gen_ops->dtr(cc); 854 cc->iv_gen_ops = NULL; 855 } 856 } 857 858 cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool); 859 if (!cc->io_pool) { 860 ti->error = "Cannot allocate crypt io mempool"; 861 goto bad3; 862 } 863 864 cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0); 865 if (!cc->page_pool) { 866 ti->error = "Cannot allocate page mempool"; 867 goto bad4; 868 } 869 870 cc->bs = bioset_create(MIN_IOS, MIN_IOS); 871 if (!cc->bs) { 872 ti->error = "Cannot allocate crypt bioset"; 873 goto bad_bs; 874 } 875 876 if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) { 877 ti->error = "Error setting key"; 878 goto bad5; 879 } 880 881 if (sscanf(argv[2], "%llu", &tmpll) != 1) { 882 ti->error = "Invalid iv_offset sector"; 883 goto bad5; 884 } 885 cc->iv_offset = tmpll; 886 887 if (sscanf(argv[4], "%llu", &tmpll) != 1) { 888 ti->error = "Invalid device sector"; 889 goto bad5; 890 } 891 cc->start = tmpll; 892 893 if (dm_get_device(ti, argv[3], cc->start, ti->len, 894 dm_table_get_mode(ti->table), &cc->dev)) { 895 ti->error = "Device lookup failed"; 896 goto bad5; 897 } 898 899 if (ivmode && cc->iv_gen_ops) { 900 if (ivopts) 901 *(ivopts - 1) = ':'; 902 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL); 903 if (!cc->iv_mode) { 904 ti->error = "Error kmallocing iv_mode string"; 905 goto bad5; 906 } 907 strcpy(cc->iv_mode, ivmode); 908 } else 909 cc->iv_mode = NULL; 910 911 ti->private = cc; 912 return 0; 913 914 bad5: 915 bioset_free(cc->bs); 916 bad_bs: 917 mempool_destroy(cc->page_pool); 918 bad4: 919 mempool_destroy(cc->io_pool); 920 bad3: 921 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 922 cc->iv_gen_ops->dtr(cc); 923 bad2: 924 crypto_free_blkcipher(tfm); 925 bad1: 926 /* Must zero key material before freeing */ 927 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 928 kfree(cc); 929 return -EINVAL; 930 } 931 932 static void crypt_dtr(struct dm_target *ti) 933 { 934 struct crypt_config *cc = (struct crypt_config *) ti->private; 935 936 bioset_free(cc->bs); 937 mempool_destroy(cc->page_pool); 938 mempool_destroy(cc->io_pool); 939 940 kfree(cc->iv_mode); 941 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 942 cc->iv_gen_ops->dtr(cc); 943 crypto_free_blkcipher(cc->tfm); 944 dm_put_device(ti, cc->dev); 945 946 /* Must zero key material before freeing */ 947 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 948 kfree(cc); 949 } 950 951 static int crypt_map(struct dm_target *ti, struct bio *bio, 952 union map_info *map_context) 953 { 954 struct crypt_config *cc = ti->private; 955 struct crypt_io *io; 956 957 io = mempool_alloc(cc->io_pool, GFP_NOIO); 958 io->target = ti; 959 io->base_bio = bio; 960 io->first_clone = NULL; 961 io->error = io->post_process = 0; 962 atomic_set(&io->pending, 0); 963 kcryptd_queue_io(io); 964 965 return DM_MAPIO_SUBMITTED; 966 } 967 968 static int crypt_status(struct dm_target *ti, status_type_t type, 969 char *result, unsigned int maxlen) 970 { 971 struct crypt_config *cc = (struct crypt_config *) ti->private; 972 unsigned int sz = 0; 973 974 switch (type) { 975 case STATUSTYPE_INFO: 976 result[0] = '\0'; 977 break; 978 979 case STATUSTYPE_TABLE: 980 if (cc->iv_mode) 981 DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode, 982 cc->iv_mode); 983 else 984 DMEMIT("%s-%s ", cc->cipher, cc->chainmode); 985 986 if (cc->key_size > 0) { 987 if ((maxlen - sz) < ((cc->key_size << 1) + 1)) 988 return -ENOMEM; 989 990 crypt_encode_key(result + sz, cc->key, cc->key_size); 991 sz += cc->key_size << 1; 992 } else { 993 if (sz >= maxlen) 994 return -ENOMEM; 995 result[sz++] = '-'; 996 } 997 998 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset, 999 cc->dev->name, (unsigned long long)cc->start); 1000 break; 1001 } 1002 return 0; 1003 } 1004 1005 static void crypt_postsuspend(struct dm_target *ti) 1006 { 1007 struct crypt_config *cc = ti->private; 1008 1009 set_bit(DM_CRYPT_SUSPENDED, &cc->flags); 1010 } 1011 1012 static int crypt_preresume(struct dm_target *ti) 1013 { 1014 struct crypt_config *cc = ti->private; 1015 1016 if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) { 1017 DMERR("aborting resume - crypt key is not set."); 1018 return -EAGAIN; 1019 } 1020 1021 return 0; 1022 } 1023 1024 static void crypt_resume(struct dm_target *ti) 1025 { 1026 struct crypt_config *cc = ti->private; 1027 1028 clear_bit(DM_CRYPT_SUSPENDED, &cc->flags); 1029 } 1030 1031 /* Message interface 1032 * key set <key> 1033 * key wipe 1034 */ 1035 static int crypt_message(struct dm_target *ti, unsigned argc, char **argv) 1036 { 1037 struct crypt_config *cc = ti->private; 1038 1039 if (argc < 2) 1040 goto error; 1041 1042 if (!strnicmp(argv[0], MESG_STR("key"))) { 1043 if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) { 1044 DMWARN("not suspended during key manipulation."); 1045 return -EINVAL; 1046 } 1047 if (argc == 3 && !strnicmp(argv[1], MESG_STR("set"))) 1048 return crypt_set_key(cc, argv[2]); 1049 if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe"))) 1050 return crypt_wipe_key(cc); 1051 } 1052 1053 error: 1054 DMWARN("unrecognised message received."); 1055 return -EINVAL; 1056 } 1057 1058 static struct target_type crypt_target = { 1059 .name = "crypt", 1060 .version= {1, 3, 0}, 1061 .module = THIS_MODULE, 1062 .ctr = crypt_ctr, 1063 .dtr = crypt_dtr, 1064 .map = crypt_map, 1065 .status = crypt_status, 1066 .postsuspend = crypt_postsuspend, 1067 .preresume = crypt_preresume, 1068 .resume = crypt_resume, 1069 .message = crypt_message, 1070 }; 1071 1072 static int __init dm_crypt_init(void) 1073 { 1074 int r; 1075 1076 _crypt_io_pool = kmem_cache_create("dm-crypt_io", 1077 sizeof(struct crypt_io), 1078 0, 0, NULL, NULL); 1079 if (!_crypt_io_pool) 1080 return -ENOMEM; 1081 1082 _kcryptd_workqueue = create_workqueue("kcryptd"); 1083 if (!_kcryptd_workqueue) { 1084 r = -ENOMEM; 1085 DMERR("couldn't create kcryptd"); 1086 goto bad1; 1087 } 1088 1089 r = dm_register_target(&crypt_target); 1090 if (r < 0) { 1091 DMERR("register failed %d", r); 1092 goto bad2; 1093 } 1094 1095 return 0; 1096 1097 bad2: 1098 destroy_workqueue(_kcryptd_workqueue); 1099 bad1: 1100 kmem_cache_destroy(_crypt_io_pool); 1101 return r; 1102 } 1103 1104 static void __exit dm_crypt_exit(void) 1105 { 1106 int r = dm_unregister_target(&crypt_target); 1107 1108 if (r < 0) 1109 DMERR("unregister failed %d", r); 1110 1111 destroy_workqueue(_kcryptd_workqueue); 1112 kmem_cache_destroy(_crypt_io_pool); 1113 } 1114 1115 module_init(dm_crypt_init); 1116 module_exit(dm_crypt_exit); 1117 1118 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>"); 1119 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption"); 1120 MODULE_LICENSE("GPL"); 1121