1 /* 2 * Copyright (C) 2003 Christophe Saout <christophe@saout.de> 3 * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org> 4 * 5 * This file is released under the GPL. 6 */ 7 8 #include <linux/module.h> 9 #include <linux/init.h> 10 #include <linux/kernel.h> 11 #include <linux/bio.h> 12 #include <linux/blkdev.h> 13 #include <linux/mempool.h> 14 #include <linux/slab.h> 15 #include <linux/crypto.h> 16 #include <linux/workqueue.h> 17 #include <asm/atomic.h> 18 #include <asm/scatterlist.h> 19 #include <asm/page.h> 20 21 #include "dm.h" 22 23 #define PFX "crypt: " 24 25 /* 26 * per bio private data 27 */ 28 struct crypt_io { 29 struct dm_target *target; 30 struct bio *bio; 31 struct bio *first_clone; 32 struct work_struct work; 33 atomic_t pending; 34 int error; 35 }; 36 37 /* 38 * context holding the current state of a multi-part conversion 39 */ 40 struct convert_context { 41 struct bio *bio_in; 42 struct bio *bio_out; 43 unsigned int offset_in; 44 unsigned int offset_out; 45 unsigned int idx_in; 46 unsigned int idx_out; 47 sector_t sector; 48 int write; 49 }; 50 51 struct crypt_config; 52 53 struct crypt_iv_operations { 54 int (*ctr)(struct crypt_config *cc, struct dm_target *ti, 55 const char *opts); 56 void (*dtr)(struct crypt_config *cc); 57 const char *(*status)(struct crypt_config *cc); 58 int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector); 59 }; 60 61 /* 62 * Crypt: maps a linear range of a block device 63 * and encrypts / decrypts at the same time. 64 */ 65 struct crypt_config { 66 struct dm_dev *dev; 67 sector_t start; 68 69 /* 70 * pool for per bio private data and 71 * for encryption buffer pages 72 */ 73 mempool_t *io_pool; 74 mempool_t *page_pool; 75 76 /* 77 * crypto related data 78 */ 79 struct crypt_iv_operations *iv_gen_ops; 80 char *iv_mode; 81 void *iv_gen_private; 82 sector_t iv_offset; 83 unsigned int iv_size; 84 85 struct crypto_tfm *tfm; 86 unsigned int key_size; 87 u8 key[0]; 88 }; 89 90 #define MIN_IOS 256 91 #define MIN_POOL_PAGES 32 92 #define MIN_BIO_PAGES 8 93 94 static kmem_cache_t *_crypt_io_pool; 95 96 /* 97 * Mempool alloc and free functions for the page 98 */ 99 static void *mempool_alloc_page(unsigned int __nocast gfp_mask, void *data) 100 { 101 return alloc_page(gfp_mask); 102 } 103 104 static void mempool_free_page(void *page, void *data) 105 { 106 __free_page(page); 107 } 108 109 110 /* 111 * Different IV generation algorithms: 112 * 113 * plain: the initial vector is the 32-bit low-endian version of the sector 114 * number, padded with zeros if neccessary. 115 * 116 * ess_iv: "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 * plumb: unimplemented, see: 121 * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454 122 */ 123 124 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 125 { 126 memset(iv, 0, cc->iv_size); 127 *(u32 *)iv = cpu_to_le32(sector & 0xffffffff); 128 129 return 0; 130 } 131 132 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, 133 const char *opts) 134 { 135 struct crypto_tfm *essiv_tfm; 136 struct crypto_tfm *hash_tfm; 137 struct scatterlist sg; 138 unsigned int saltsize; 139 u8 *salt; 140 141 if (opts == NULL) { 142 ti->error = PFX "Digest algorithm missing for ESSIV mode"; 143 return -EINVAL; 144 } 145 146 /* Hash the cipher key with the given hash algorithm */ 147 hash_tfm = crypto_alloc_tfm(opts, 0); 148 if (hash_tfm == NULL) { 149 ti->error = PFX "Error initializing ESSIV hash"; 150 return -EINVAL; 151 } 152 153 if (crypto_tfm_alg_type(hash_tfm) != CRYPTO_ALG_TYPE_DIGEST) { 154 ti->error = PFX "Expected digest algorithm for ESSIV hash"; 155 crypto_free_tfm(hash_tfm); 156 return -EINVAL; 157 } 158 159 saltsize = crypto_tfm_alg_digestsize(hash_tfm); 160 salt = kmalloc(saltsize, GFP_KERNEL); 161 if (salt == NULL) { 162 ti->error = PFX "Error kmallocing salt storage in ESSIV"; 163 crypto_free_tfm(hash_tfm); 164 return -ENOMEM; 165 } 166 167 sg.page = virt_to_page(cc->key); 168 sg.offset = offset_in_page(cc->key); 169 sg.length = cc->key_size; 170 crypto_digest_digest(hash_tfm, &sg, 1, salt); 171 crypto_free_tfm(hash_tfm); 172 173 /* Setup the essiv_tfm with the given salt */ 174 essiv_tfm = crypto_alloc_tfm(crypto_tfm_alg_name(cc->tfm), 175 CRYPTO_TFM_MODE_ECB); 176 if (essiv_tfm == NULL) { 177 ti->error = PFX "Error allocating crypto tfm for ESSIV"; 178 kfree(salt); 179 return -EINVAL; 180 } 181 if (crypto_tfm_alg_blocksize(essiv_tfm) 182 != crypto_tfm_alg_ivsize(cc->tfm)) { 183 ti->error = PFX "Block size of ESSIV cipher does " 184 "not match IV size of block cipher"; 185 crypto_free_tfm(essiv_tfm); 186 kfree(salt); 187 return -EINVAL; 188 } 189 if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) { 190 ti->error = PFX "Failed to set key for ESSIV cipher"; 191 crypto_free_tfm(essiv_tfm); 192 kfree(salt); 193 return -EINVAL; 194 } 195 kfree(salt); 196 197 cc->iv_gen_private = (void *)essiv_tfm; 198 return 0; 199 } 200 201 static void crypt_iv_essiv_dtr(struct crypt_config *cc) 202 { 203 crypto_free_tfm((struct crypto_tfm *)cc->iv_gen_private); 204 cc->iv_gen_private = NULL; 205 } 206 207 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 208 { 209 struct scatterlist sg = { NULL, }; 210 211 memset(iv, 0, cc->iv_size); 212 *(u64 *)iv = cpu_to_le64(sector); 213 214 sg.page = virt_to_page(iv); 215 sg.offset = offset_in_page(iv); 216 sg.length = cc->iv_size; 217 crypto_cipher_encrypt((struct crypto_tfm *)cc->iv_gen_private, 218 &sg, &sg, cc->iv_size); 219 220 return 0; 221 } 222 223 static struct crypt_iv_operations crypt_iv_plain_ops = { 224 .generator = crypt_iv_plain_gen 225 }; 226 227 static struct crypt_iv_operations crypt_iv_essiv_ops = { 228 .ctr = crypt_iv_essiv_ctr, 229 .dtr = crypt_iv_essiv_dtr, 230 .generator = crypt_iv_essiv_gen 231 }; 232 233 234 static inline int 235 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out, 236 struct scatterlist *in, unsigned int length, 237 int write, sector_t sector) 238 { 239 u8 iv[cc->iv_size]; 240 int r; 241 242 if (cc->iv_gen_ops) { 243 r = cc->iv_gen_ops->generator(cc, iv, sector); 244 if (r < 0) 245 return r; 246 247 if (write) 248 r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv); 249 else 250 r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv); 251 } else { 252 if (write) 253 r = crypto_cipher_encrypt(cc->tfm, out, in, length); 254 else 255 r = crypto_cipher_decrypt(cc->tfm, out, in, length); 256 } 257 258 return r; 259 } 260 261 static void 262 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx, 263 struct bio *bio_out, struct bio *bio_in, 264 sector_t sector, int write) 265 { 266 ctx->bio_in = bio_in; 267 ctx->bio_out = bio_out; 268 ctx->offset_in = 0; 269 ctx->offset_out = 0; 270 ctx->idx_in = bio_in ? bio_in->bi_idx : 0; 271 ctx->idx_out = bio_out ? bio_out->bi_idx : 0; 272 ctx->sector = sector + cc->iv_offset; 273 ctx->write = write; 274 } 275 276 /* 277 * Encrypt / decrypt data from one bio to another one (can be the same one) 278 */ 279 static int crypt_convert(struct crypt_config *cc, 280 struct convert_context *ctx) 281 { 282 int r = 0; 283 284 while(ctx->idx_in < ctx->bio_in->bi_vcnt && 285 ctx->idx_out < ctx->bio_out->bi_vcnt) { 286 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in); 287 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out); 288 struct scatterlist sg_in = { 289 .page = bv_in->bv_page, 290 .offset = bv_in->bv_offset + ctx->offset_in, 291 .length = 1 << SECTOR_SHIFT 292 }; 293 struct scatterlist sg_out = { 294 .page = bv_out->bv_page, 295 .offset = bv_out->bv_offset + ctx->offset_out, 296 .length = 1 << SECTOR_SHIFT 297 }; 298 299 ctx->offset_in += sg_in.length; 300 if (ctx->offset_in >= bv_in->bv_len) { 301 ctx->offset_in = 0; 302 ctx->idx_in++; 303 } 304 305 ctx->offset_out += sg_out.length; 306 if (ctx->offset_out >= bv_out->bv_len) { 307 ctx->offset_out = 0; 308 ctx->idx_out++; 309 } 310 311 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length, 312 ctx->write, ctx->sector); 313 if (r < 0) 314 break; 315 316 ctx->sector++; 317 } 318 319 return r; 320 } 321 322 /* 323 * Generate a new unfragmented bio with the given size 324 * This should never violate the device limitations 325 * May return a smaller bio when running out of pages 326 */ 327 static struct bio * 328 crypt_alloc_buffer(struct crypt_config *cc, unsigned int size, 329 struct bio *base_bio, unsigned int *bio_vec_idx) 330 { 331 struct bio *bio; 332 unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 333 int gfp_mask = GFP_NOIO | __GFP_HIGHMEM; 334 unsigned int i; 335 336 /* 337 * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and 338 * to fail earlier. This is not necessary but increases throughput. 339 * FIXME: Is this really intelligent? 340 */ 341 if (base_bio) 342 bio = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC); 343 else 344 bio = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs); 345 if (!bio) 346 return NULL; 347 348 /* if the last bio was not complete, continue where that one ended */ 349 bio->bi_idx = *bio_vec_idx; 350 bio->bi_vcnt = *bio_vec_idx; 351 bio->bi_size = 0; 352 bio->bi_flags &= ~(1 << BIO_SEG_VALID); 353 354 /* bio->bi_idx pages have already been allocated */ 355 size -= bio->bi_idx * PAGE_SIZE; 356 357 for(i = bio->bi_idx; i < nr_iovecs; i++) { 358 struct bio_vec *bv = bio_iovec_idx(bio, i); 359 360 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask); 361 if (!bv->bv_page) 362 break; 363 364 /* 365 * if additional pages cannot be allocated without waiting, 366 * return a partially allocated bio, the caller will then try 367 * to allocate additional bios while submitting this partial bio 368 */ 369 if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1)) 370 gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; 371 372 bv->bv_offset = 0; 373 if (size > PAGE_SIZE) 374 bv->bv_len = PAGE_SIZE; 375 else 376 bv->bv_len = size; 377 378 bio->bi_size += bv->bv_len; 379 bio->bi_vcnt++; 380 size -= bv->bv_len; 381 } 382 383 if (!bio->bi_size) { 384 bio_put(bio); 385 return NULL; 386 } 387 388 /* 389 * Remember the last bio_vec allocated to be able 390 * to correctly continue after the splitting. 391 */ 392 *bio_vec_idx = bio->bi_vcnt; 393 394 return bio; 395 } 396 397 static void crypt_free_buffer_pages(struct crypt_config *cc, 398 struct bio *bio, unsigned int bytes) 399 { 400 unsigned int i, start, end; 401 struct bio_vec *bv; 402 403 /* 404 * This is ugly, but Jens Axboe thinks that using bi_idx in the 405 * endio function is too dangerous at the moment, so I calculate the 406 * correct position using bi_vcnt and bi_size. 407 * The bv_offset and bv_len fields might already be modified but we 408 * know that we always allocated whole pages. 409 * A fix to the bi_idx issue in the kernel is in the works, so 410 * we will hopefully be able to revert to the cleaner solution soon. 411 */ 412 i = bio->bi_vcnt - 1; 413 bv = bio_iovec_idx(bio, i); 414 end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size; 415 start = end - bytes; 416 417 start >>= PAGE_SHIFT; 418 if (!bio->bi_size) 419 end = bio->bi_vcnt; 420 else 421 end >>= PAGE_SHIFT; 422 423 for(i = start; i < end; i++) { 424 bv = bio_iovec_idx(bio, i); 425 BUG_ON(!bv->bv_page); 426 mempool_free(bv->bv_page, cc->page_pool); 427 bv->bv_page = NULL; 428 } 429 } 430 431 /* 432 * One of the bios was finished. Check for completion of 433 * the whole request and correctly clean up the buffer. 434 */ 435 static void dec_pending(struct crypt_io *io, int error) 436 { 437 struct crypt_config *cc = (struct crypt_config *) io->target->private; 438 439 if (error < 0) 440 io->error = error; 441 442 if (!atomic_dec_and_test(&io->pending)) 443 return; 444 445 if (io->first_clone) 446 bio_put(io->first_clone); 447 448 bio_endio(io->bio, io->bio->bi_size, io->error); 449 450 mempool_free(io, cc->io_pool); 451 } 452 453 /* 454 * kcryptd: 455 * 456 * Needed because it would be very unwise to do decryption in an 457 * interrupt context, so bios returning from read requests get 458 * queued here. 459 */ 460 static struct workqueue_struct *_kcryptd_workqueue; 461 462 static void kcryptd_do_work(void *data) 463 { 464 struct crypt_io *io = (struct crypt_io *) data; 465 struct crypt_config *cc = (struct crypt_config *) io->target->private; 466 struct convert_context ctx; 467 int r; 468 469 crypt_convert_init(cc, &ctx, io->bio, io->bio, 470 io->bio->bi_sector - io->target->begin, 0); 471 r = crypt_convert(cc, &ctx); 472 473 dec_pending(io, r); 474 } 475 476 static void kcryptd_queue_io(struct crypt_io *io) 477 { 478 INIT_WORK(&io->work, kcryptd_do_work, io); 479 queue_work(_kcryptd_workqueue, &io->work); 480 } 481 482 /* 483 * Decode key from its hex representation 484 */ 485 static int crypt_decode_key(u8 *key, char *hex, unsigned int size) 486 { 487 char buffer[3]; 488 char *endp; 489 unsigned int i; 490 491 buffer[2] = '\0'; 492 493 for(i = 0; i < size; i++) { 494 buffer[0] = *hex++; 495 buffer[1] = *hex++; 496 497 key[i] = (u8)simple_strtoul(buffer, &endp, 16); 498 499 if (endp != &buffer[2]) 500 return -EINVAL; 501 } 502 503 if (*hex != '\0') 504 return -EINVAL; 505 506 return 0; 507 } 508 509 /* 510 * Encode key into its hex representation 511 */ 512 static void crypt_encode_key(char *hex, u8 *key, unsigned int size) 513 { 514 unsigned int i; 515 516 for(i = 0; i < size; i++) { 517 sprintf(hex, "%02x", *key); 518 hex += 2; 519 key++; 520 } 521 } 522 523 /* 524 * Construct an encryption mapping: 525 * <cipher> <key> <iv_offset> <dev_path> <start> 526 */ 527 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) 528 { 529 struct crypt_config *cc; 530 struct crypto_tfm *tfm; 531 char *tmp; 532 char *cipher; 533 char *chainmode; 534 char *ivmode; 535 char *ivopts; 536 unsigned int crypto_flags; 537 unsigned int key_size; 538 539 if (argc != 5) { 540 ti->error = PFX "Not enough arguments"; 541 return -EINVAL; 542 } 543 544 tmp = argv[0]; 545 cipher = strsep(&tmp, "-"); 546 chainmode = strsep(&tmp, "-"); 547 ivopts = strsep(&tmp, "-"); 548 ivmode = strsep(&ivopts, ":"); 549 550 if (tmp) 551 DMWARN(PFX "Unexpected additional cipher options"); 552 553 key_size = strlen(argv[1]) >> 1; 554 555 cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL); 556 if (cc == NULL) { 557 ti->error = 558 PFX "Cannot allocate transparent encryption context"; 559 return -ENOMEM; 560 } 561 562 cc->key_size = key_size; 563 if ((!key_size && strcmp(argv[1], "-") != 0) || 564 (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) { 565 ti->error = PFX "Error decoding key"; 566 goto bad1; 567 } 568 569 /* Compatiblity mode for old dm-crypt cipher strings */ 570 if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) { 571 chainmode = "cbc"; 572 ivmode = "plain"; 573 } 574 575 /* Choose crypto_flags according to chainmode */ 576 if (strcmp(chainmode, "cbc") == 0) 577 crypto_flags = CRYPTO_TFM_MODE_CBC; 578 else if (strcmp(chainmode, "ecb") == 0) 579 crypto_flags = CRYPTO_TFM_MODE_ECB; 580 else { 581 ti->error = PFX "Unknown chaining mode"; 582 goto bad1; 583 } 584 585 if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) { 586 ti->error = PFX "This chaining mode requires an IV mechanism"; 587 goto bad1; 588 } 589 590 tfm = crypto_alloc_tfm(cipher, crypto_flags); 591 if (!tfm) { 592 ti->error = PFX "Error allocating crypto tfm"; 593 goto bad1; 594 } 595 if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) { 596 ti->error = PFX "Expected cipher algorithm"; 597 goto bad2; 598 } 599 600 cc->tfm = tfm; 601 602 /* 603 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>". 604 * See comments at iv code 605 */ 606 607 if (ivmode == NULL) 608 cc->iv_gen_ops = NULL; 609 else if (strcmp(ivmode, "plain") == 0) 610 cc->iv_gen_ops = &crypt_iv_plain_ops; 611 else if (strcmp(ivmode, "essiv") == 0) 612 cc->iv_gen_ops = &crypt_iv_essiv_ops; 613 else { 614 ti->error = PFX "Invalid IV mode"; 615 goto bad2; 616 } 617 618 if (cc->iv_gen_ops && cc->iv_gen_ops->ctr && 619 cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) 620 goto bad2; 621 622 if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv) 623 /* at least a 64 bit sector number should fit in our buffer */ 624 cc->iv_size = max(crypto_tfm_alg_ivsize(tfm), 625 (unsigned int)(sizeof(u64) / sizeof(u8))); 626 else { 627 cc->iv_size = 0; 628 if (cc->iv_gen_ops) { 629 DMWARN(PFX "Selected cipher does not support IVs"); 630 if (cc->iv_gen_ops->dtr) 631 cc->iv_gen_ops->dtr(cc); 632 cc->iv_gen_ops = NULL; 633 } 634 } 635 636 cc->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab, 637 mempool_free_slab, _crypt_io_pool); 638 if (!cc->io_pool) { 639 ti->error = PFX "Cannot allocate crypt io mempool"; 640 goto bad3; 641 } 642 643 cc->page_pool = mempool_create(MIN_POOL_PAGES, mempool_alloc_page, 644 mempool_free_page, NULL); 645 if (!cc->page_pool) { 646 ti->error = PFX "Cannot allocate page mempool"; 647 goto bad4; 648 } 649 650 if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) { 651 ti->error = PFX "Error setting key"; 652 goto bad5; 653 } 654 655 if (sscanf(argv[2], SECTOR_FORMAT, &cc->iv_offset) != 1) { 656 ti->error = PFX "Invalid iv_offset sector"; 657 goto bad5; 658 } 659 660 if (sscanf(argv[4], SECTOR_FORMAT, &cc->start) != 1) { 661 ti->error = PFX "Invalid device sector"; 662 goto bad5; 663 } 664 665 if (dm_get_device(ti, argv[3], cc->start, ti->len, 666 dm_table_get_mode(ti->table), &cc->dev)) { 667 ti->error = PFX "Device lookup failed"; 668 goto bad5; 669 } 670 671 if (ivmode && cc->iv_gen_ops) { 672 if (ivopts) 673 *(ivopts - 1) = ':'; 674 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL); 675 if (!cc->iv_mode) { 676 ti->error = PFX "Error kmallocing iv_mode string"; 677 goto bad5; 678 } 679 strcpy(cc->iv_mode, ivmode); 680 } else 681 cc->iv_mode = NULL; 682 683 ti->private = cc; 684 return 0; 685 686 bad5: 687 mempool_destroy(cc->page_pool); 688 bad4: 689 mempool_destroy(cc->io_pool); 690 bad3: 691 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 692 cc->iv_gen_ops->dtr(cc); 693 bad2: 694 crypto_free_tfm(tfm); 695 bad1: 696 kfree(cc); 697 return -EINVAL; 698 } 699 700 static void crypt_dtr(struct dm_target *ti) 701 { 702 struct crypt_config *cc = (struct crypt_config *) ti->private; 703 704 mempool_destroy(cc->page_pool); 705 mempool_destroy(cc->io_pool); 706 707 kfree(cc->iv_mode); 708 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 709 cc->iv_gen_ops->dtr(cc); 710 crypto_free_tfm(cc->tfm); 711 dm_put_device(ti, cc->dev); 712 kfree(cc); 713 } 714 715 static int crypt_endio(struct bio *bio, unsigned int done, int error) 716 { 717 struct crypt_io *io = (struct crypt_io *) bio->bi_private; 718 struct crypt_config *cc = (struct crypt_config *) io->target->private; 719 720 if (bio_data_dir(bio) == WRITE) { 721 /* 722 * free the processed pages, even if 723 * it's only a partially completed write 724 */ 725 crypt_free_buffer_pages(cc, bio, done); 726 } 727 728 if (bio->bi_size) 729 return 1; 730 731 bio_put(bio); 732 733 /* 734 * successful reads are decrypted by the worker thread 735 */ 736 if ((bio_data_dir(bio) == READ) 737 && bio_flagged(bio, BIO_UPTODATE)) { 738 kcryptd_queue_io(io); 739 return 0; 740 } 741 742 dec_pending(io, error); 743 return error; 744 } 745 746 static inline struct bio * 747 crypt_clone(struct crypt_config *cc, struct crypt_io *io, struct bio *bio, 748 sector_t sector, unsigned int *bvec_idx, 749 struct convert_context *ctx) 750 { 751 struct bio *clone; 752 753 if (bio_data_dir(bio) == WRITE) { 754 clone = crypt_alloc_buffer(cc, bio->bi_size, 755 io->first_clone, bvec_idx); 756 if (clone) { 757 ctx->bio_out = clone; 758 if (crypt_convert(cc, ctx) < 0) { 759 crypt_free_buffer_pages(cc, clone, 760 clone->bi_size); 761 bio_put(clone); 762 return NULL; 763 } 764 } 765 } else { 766 /* 767 * The block layer might modify the bvec array, so always 768 * copy the required bvecs because we need the original 769 * one in order to decrypt the whole bio data *afterwards*. 770 */ 771 clone = bio_alloc(GFP_NOIO, bio_segments(bio)); 772 if (clone) { 773 clone->bi_idx = 0; 774 clone->bi_vcnt = bio_segments(bio); 775 clone->bi_size = bio->bi_size; 776 memcpy(clone->bi_io_vec, bio_iovec(bio), 777 sizeof(struct bio_vec) * clone->bi_vcnt); 778 } 779 } 780 781 if (!clone) 782 return NULL; 783 784 clone->bi_private = io; 785 clone->bi_end_io = crypt_endio; 786 clone->bi_bdev = cc->dev->bdev; 787 clone->bi_sector = cc->start + sector; 788 clone->bi_rw = bio->bi_rw; 789 790 return clone; 791 } 792 793 static int crypt_map(struct dm_target *ti, struct bio *bio, 794 union map_info *map_context) 795 { 796 struct crypt_config *cc = (struct crypt_config *) ti->private; 797 struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO); 798 struct convert_context ctx; 799 struct bio *clone; 800 unsigned int remaining = bio->bi_size; 801 sector_t sector = bio->bi_sector - ti->begin; 802 unsigned int bvec_idx = 0; 803 804 io->target = ti; 805 io->bio = bio; 806 io->first_clone = NULL; 807 io->error = 0; 808 atomic_set(&io->pending, 1); /* hold a reference */ 809 810 if (bio_data_dir(bio) == WRITE) 811 crypt_convert_init(cc, &ctx, NULL, bio, sector, 1); 812 813 /* 814 * The allocated buffers can be smaller than the whole bio, 815 * so repeat the whole process until all the data can be handled. 816 */ 817 while (remaining) { 818 clone = crypt_clone(cc, io, bio, sector, &bvec_idx, &ctx); 819 if (!clone) 820 goto cleanup; 821 822 if (!io->first_clone) { 823 /* 824 * hold a reference to the first clone, because it 825 * holds the bio_vec array and that can't be freed 826 * before all other clones are released 827 */ 828 bio_get(clone); 829 io->first_clone = clone; 830 } 831 atomic_inc(&io->pending); 832 833 remaining -= clone->bi_size; 834 sector += bio_sectors(clone); 835 836 generic_make_request(clone); 837 838 /* out of memory -> run queues */ 839 if (remaining) 840 blk_congestion_wait(bio_data_dir(clone), HZ/100); 841 } 842 843 /* drop reference, clones could have returned before we reach this */ 844 dec_pending(io, 0); 845 return 0; 846 847 cleanup: 848 if (io->first_clone) { 849 dec_pending(io, -ENOMEM); 850 return 0; 851 } 852 853 /* if no bio has been dispatched yet, we can directly return the error */ 854 mempool_free(io, cc->io_pool); 855 return -ENOMEM; 856 } 857 858 static int crypt_status(struct dm_target *ti, status_type_t type, 859 char *result, unsigned int maxlen) 860 { 861 struct crypt_config *cc = (struct crypt_config *) ti->private; 862 const char *cipher; 863 const char *chainmode = NULL; 864 unsigned int sz = 0; 865 866 switch (type) { 867 case STATUSTYPE_INFO: 868 result[0] = '\0'; 869 break; 870 871 case STATUSTYPE_TABLE: 872 cipher = crypto_tfm_alg_name(cc->tfm); 873 874 switch(cc->tfm->crt_cipher.cit_mode) { 875 case CRYPTO_TFM_MODE_CBC: 876 chainmode = "cbc"; 877 break; 878 case CRYPTO_TFM_MODE_ECB: 879 chainmode = "ecb"; 880 break; 881 default: 882 BUG(); 883 } 884 885 if (cc->iv_mode) 886 DMEMIT("%s-%s-%s ", cipher, chainmode, cc->iv_mode); 887 else 888 DMEMIT("%s-%s ", cipher, chainmode); 889 890 if (cc->key_size > 0) { 891 if ((maxlen - sz) < ((cc->key_size << 1) + 1)) 892 return -ENOMEM; 893 894 crypt_encode_key(result + sz, cc->key, cc->key_size); 895 sz += cc->key_size << 1; 896 } else { 897 if (sz >= maxlen) 898 return -ENOMEM; 899 result[sz++] = '-'; 900 } 901 902 DMEMIT(" " SECTOR_FORMAT " %s " SECTOR_FORMAT, 903 cc->iv_offset, cc->dev->name, cc->start); 904 break; 905 } 906 return 0; 907 } 908 909 static struct target_type crypt_target = { 910 .name = "crypt", 911 .version= {1, 1, 0}, 912 .module = THIS_MODULE, 913 .ctr = crypt_ctr, 914 .dtr = crypt_dtr, 915 .map = crypt_map, 916 .status = crypt_status, 917 }; 918 919 static int __init dm_crypt_init(void) 920 { 921 int r; 922 923 _crypt_io_pool = kmem_cache_create("dm-crypt_io", 924 sizeof(struct crypt_io), 925 0, 0, NULL, NULL); 926 if (!_crypt_io_pool) 927 return -ENOMEM; 928 929 _kcryptd_workqueue = create_workqueue("kcryptd"); 930 if (!_kcryptd_workqueue) { 931 r = -ENOMEM; 932 DMERR(PFX "couldn't create kcryptd"); 933 goto bad1; 934 } 935 936 r = dm_register_target(&crypt_target); 937 if (r < 0) { 938 DMERR(PFX "register failed %d", r); 939 goto bad2; 940 } 941 942 return 0; 943 944 bad2: 945 destroy_workqueue(_kcryptd_workqueue); 946 bad1: 947 kmem_cache_destroy(_crypt_io_pool); 948 return r; 949 } 950 951 static void __exit dm_crypt_exit(void) 952 { 953 int r = dm_unregister_target(&crypt_target); 954 955 if (r < 0) 956 DMERR(PFX "unregister failed %d", r); 957 958 destroy_workqueue(_kcryptd_workqueue); 959 kmem_cache_destroy(_crypt_io_pool); 960 } 961 962 module_init(dm_crypt_init); 963 module_exit(dm_crypt_exit); 964 965 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>"); 966 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption"); 967 MODULE_LICENSE("GPL"); 968