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, CRYPTO_TFM_REQ_MAY_SLEEP); 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 CRYPTO_TFM_REQ_MAY_SLEEP); 177 if (essiv_tfm == NULL) { 178 ti->error = PFX "Error allocating crypto tfm for ESSIV"; 179 kfree(salt); 180 return -EINVAL; 181 } 182 if (crypto_tfm_alg_blocksize(essiv_tfm) 183 != crypto_tfm_alg_ivsize(cc->tfm)) { 184 ti->error = PFX "Block size of ESSIV cipher does " 185 "not match IV size of block cipher"; 186 crypto_free_tfm(essiv_tfm); 187 kfree(salt); 188 return -EINVAL; 189 } 190 if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) { 191 ti->error = PFX "Failed to set key for ESSIV cipher"; 192 crypto_free_tfm(essiv_tfm); 193 kfree(salt); 194 return -EINVAL; 195 } 196 kfree(salt); 197 198 cc->iv_gen_private = (void *)essiv_tfm; 199 return 0; 200 } 201 202 static void crypt_iv_essiv_dtr(struct crypt_config *cc) 203 { 204 crypto_free_tfm((struct crypto_tfm *)cc->iv_gen_private); 205 cc->iv_gen_private = NULL; 206 } 207 208 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 209 { 210 struct scatterlist sg = { NULL, }; 211 212 memset(iv, 0, cc->iv_size); 213 *(u64 *)iv = cpu_to_le64(sector); 214 215 sg.page = virt_to_page(iv); 216 sg.offset = offset_in_page(iv); 217 sg.length = cc->iv_size; 218 crypto_cipher_encrypt((struct crypto_tfm *)cc->iv_gen_private, 219 &sg, &sg, cc->iv_size); 220 221 return 0; 222 } 223 224 static struct crypt_iv_operations crypt_iv_plain_ops = { 225 .generator = crypt_iv_plain_gen 226 }; 227 228 static struct crypt_iv_operations crypt_iv_essiv_ops = { 229 .ctr = crypt_iv_essiv_ctr, 230 .dtr = crypt_iv_essiv_dtr, 231 .generator = crypt_iv_essiv_gen 232 }; 233 234 235 static inline int 236 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out, 237 struct scatterlist *in, unsigned int length, 238 int write, sector_t sector) 239 { 240 u8 iv[cc->iv_size]; 241 int r; 242 243 if (cc->iv_gen_ops) { 244 r = cc->iv_gen_ops->generator(cc, iv, sector); 245 if (r < 0) 246 return r; 247 248 if (write) 249 r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv); 250 else 251 r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv); 252 } else { 253 if (write) 254 r = crypto_cipher_encrypt(cc->tfm, out, in, length); 255 else 256 r = crypto_cipher_decrypt(cc->tfm, out, in, length); 257 } 258 259 return r; 260 } 261 262 static void 263 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx, 264 struct bio *bio_out, struct bio *bio_in, 265 sector_t sector, int write) 266 { 267 ctx->bio_in = bio_in; 268 ctx->bio_out = bio_out; 269 ctx->offset_in = 0; 270 ctx->offset_out = 0; 271 ctx->idx_in = bio_in ? bio_in->bi_idx : 0; 272 ctx->idx_out = bio_out ? bio_out->bi_idx : 0; 273 ctx->sector = sector + cc->iv_offset; 274 ctx->write = write; 275 } 276 277 /* 278 * Encrypt / decrypt data from one bio to another one (can be the same one) 279 */ 280 static int crypt_convert(struct crypt_config *cc, 281 struct convert_context *ctx) 282 { 283 int r = 0; 284 285 while(ctx->idx_in < ctx->bio_in->bi_vcnt && 286 ctx->idx_out < ctx->bio_out->bi_vcnt) { 287 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in); 288 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out); 289 struct scatterlist sg_in = { 290 .page = bv_in->bv_page, 291 .offset = bv_in->bv_offset + ctx->offset_in, 292 .length = 1 << SECTOR_SHIFT 293 }; 294 struct scatterlist sg_out = { 295 .page = bv_out->bv_page, 296 .offset = bv_out->bv_offset + ctx->offset_out, 297 .length = 1 << SECTOR_SHIFT 298 }; 299 300 ctx->offset_in += sg_in.length; 301 if (ctx->offset_in >= bv_in->bv_len) { 302 ctx->offset_in = 0; 303 ctx->idx_in++; 304 } 305 306 ctx->offset_out += sg_out.length; 307 if (ctx->offset_out >= bv_out->bv_len) { 308 ctx->offset_out = 0; 309 ctx->idx_out++; 310 } 311 312 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length, 313 ctx->write, ctx->sector); 314 if (r < 0) 315 break; 316 317 ctx->sector++; 318 } 319 320 return r; 321 } 322 323 /* 324 * Generate a new unfragmented bio with the given size 325 * This should never violate the device limitations 326 * May return a smaller bio when running out of pages 327 */ 328 static struct bio * 329 crypt_alloc_buffer(struct crypt_config *cc, unsigned int size, 330 struct bio *base_bio, unsigned int *bio_vec_idx) 331 { 332 struct bio *bio; 333 unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 334 int gfp_mask = GFP_NOIO | __GFP_HIGHMEM; 335 unsigned int i; 336 337 /* 338 * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and 339 * to fail earlier. This is not necessary but increases throughput. 340 * FIXME: Is this really intelligent? 341 */ 342 if (base_bio) 343 bio = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC); 344 else 345 bio = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs); 346 if (!bio) 347 return NULL; 348 349 /* if the last bio was not complete, continue where that one ended */ 350 bio->bi_idx = *bio_vec_idx; 351 bio->bi_vcnt = *bio_vec_idx; 352 bio->bi_size = 0; 353 bio->bi_flags &= ~(1 << BIO_SEG_VALID); 354 355 /* bio->bi_idx pages have already been allocated */ 356 size -= bio->bi_idx * PAGE_SIZE; 357 358 for(i = bio->bi_idx; i < nr_iovecs; i++) { 359 struct bio_vec *bv = bio_iovec_idx(bio, i); 360 361 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask); 362 if (!bv->bv_page) 363 break; 364 365 /* 366 * if additional pages cannot be allocated without waiting, 367 * return a partially allocated bio, the caller will then try 368 * to allocate additional bios while submitting this partial bio 369 */ 370 if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1)) 371 gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; 372 373 bv->bv_offset = 0; 374 if (size > PAGE_SIZE) 375 bv->bv_len = PAGE_SIZE; 376 else 377 bv->bv_len = size; 378 379 bio->bi_size += bv->bv_len; 380 bio->bi_vcnt++; 381 size -= bv->bv_len; 382 } 383 384 if (!bio->bi_size) { 385 bio_put(bio); 386 return NULL; 387 } 388 389 /* 390 * Remember the last bio_vec allocated to be able 391 * to correctly continue after the splitting. 392 */ 393 *bio_vec_idx = bio->bi_vcnt; 394 395 return bio; 396 } 397 398 static void crypt_free_buffer_pages(struct crypt_config *cc, 399 struct bio *bio, unsigned int bytes) 400 { 401 unsigned int i, start, end; 402 struct bio_vec *bv; 403 404 /* 405 * This is ugly, but Jens Axboe thinks that using bi_idx in the 406 * endio function is too dangerous at the moment, so I calculate the 407 * correct position using bi_vcnt and bi_size. 408 * The bv_offset and bv_len fields might already be modified but we 409 * know that we always allocated whole pages. 410 * A fix to the bi_idx issue in the kernel is in the works, so 411 * we will hopefully be able to revert to the cleaner solution soon. 412 */ 413 i = bio->bi_vcnt - 1; 414 bv = bio_iovec_idx(bio, i); 415 end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size; 416 start = end - bytes; 417 418 start >>= PAGE_SHIFT; 419 if (!bio->bi_size) 420 end = bio->bi_vcnt; 421 else 422 end >>= PAGE_SHIFT; 423 424 for(i = start; i < end; i++) { 425 bv = bio_iovec_idx(bio, i); 426 BUG_ON(!bv->bv_page); 427 mempool_free(bv->bv_page, cc->page_pool); 428 bv->bv_page = NULL; 429 } 430 } 431 432 /* 433 * One of the bios was finished. Check for completion of 434 * the whole request and correctly clean up the buffer. 435 */ 436 static void dec_pending(struct crypt_io *io, int error) 437 { 438 struct crypt_config *cc = (struct crypt_config *) io->target->private; 439 440 if (error < 0) 441 io->error = error; 442 443 if (!atomic_dec_and_test(&io->pending)) 444 return; 445 446 if (io->first_clone) 447 bio_put(io->first_clone); 448 449 bio_endio(io->bio, io->bio->bi_size, io->error); 450 451 mempool_free(io, cc->io_pool); 452 } 453 454 /* 455 * kcryptd: 456 * 457 * Needed because it would be very unwise to do decryption in an 458 * interrupt context, so bios returning from read requests get 459 * queued here. 460 */ 461 static struct workqueue_struct *_kcryptd_workqueue; 462 463 static void kcryptd_do_work(void *data) 464 { 465 struct crypt_io *io = (struct crypt_io *) data; 466 struct crypt_config *cc = (struct crypt_config *) io->target->private; 467 struct convert_context ctx; 468 int r; 469 470 crypt_convert_init(cc, &ctx, io->bio, io->bio, 471 io->bio->bi_sector - io->target->begin, 0); 472 r = crypt_convert(cc, &ctx); 473 474 dec_pending(io, r); 475 } 476 477 static void kcryptd_queue_io(struct crypt_io *io) 478 { 479 INIT_WORK(&io->work, kcryptd_do_work, io); 480 queue_work(_kcryptd_workqueue, &io->work); 481 } 482 483 /* 484 * Decode key from its hex representation 485 */ 486 static int crypt_decode_key(u8 *key, char *hex, unsigned int size) 487 { 488 char buffer[3]; 489 char *endp; 490 unsigned int i; 491 492 buffer[2] = '\0'; 493 494 for(i = 0; i < size; i++) { 495 buffer[0] = *hex++; 496 buffer[1] = *hex++; 497 498 key[i] = (u8)simple_strtoul(buffer, &endp, 16); 499 500 if (endp != &buffer[2]) 501 return -EINVAL; 502 } 503 504 if (*hex != '\0') 505 return -EINVAL; 506 507 return 0; 508 } 509 510 /* 511 * Encode key into its hex representation 512 */ 513 static void crypt_encode_key(char *hex, u8 *key, unsigned int size) 514 { 515 unsigned int i; 516 517 for(i = 0; i < size; i++) { 518 sprintf(hex, "%02x", *key); 519 hex += 2; 520 key++; 521 } 522 } 523 524 /* 525 * Construct an encryption mapping: 526 * <cipher> <key> <iv_offset> <dev_path> <start> 527 */ 528 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) 529 { 530 struct crypt_config *cc; 531 struct crypto_tfm *tfm; 532 char *tmp; 533 char *cipher; 534 char *chainmode; 535 char *ivmode; 536 char *ivopts; 537 unsigned int crypto_flags; 538 unsigned int key_size; 539 540 if (argc != 5) { 541 ti->error = PFX "Not enough arguments"; 542 return -EINVAL; 543 } 544 545 tmp = argv[0]; 546 cipher = strsep(&tmp, "-"); 547 chainmode = strsep(&tmp, "-"); 548 ivopts = strsep(&tmp, "-"); 549 ivmode = strsep(&ivopts, ":"); 550 551 if (tmp) 552 DMWARN(PFX "Unexpected additional cipher options"); 553 554 key_size = strlen(argv[1]) >> 1; 555 556 cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL); 557 if (cc == NULL) { 558 ti->error = 559 PFX "Cannot allocate transparent encryption context"; 560 return -ENOMEM; 561 } 562 563 cc->key_size = key_size; 564 if ((!key_size && strcmp(argv[1], "-") != 0) || 565 (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) { 566 ti->error = PFX "Error decoding key"; 567 goto bad1; 568 } 569 570 /* Compatiblity mode for old dm-crypt cipher strings */ 571 if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) { 572 chainmode = "cbc"; 573 ivmode = "plain"; 574 } 575 576 /* Choose crypto_flags according to chainmode */ 577 if (strcmp(chainmode, "cbc") == 0) 578 crypto_flags = CRYPTO_TFM_MODE_CBC; 579 else if (strcmp(chainmode, "ecb") == 0) 580 crypto_flags = CRYPTO_TFM_MODE_ECB; 581 else { 582 ti->error = PFX "Unknown chaining mode"; 583 goto bad1; 584 } 585 586 if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) { 587 ti->error = PFX "This chaining mode requires an IV mechanism"; 588 goto bad1; 589 } 590 591 tfm = crypto_alloc_tfm(cipher, crypto_flags | CRYPTO_TFM_REQ_MAY_SLEEP); 592 if (!tfm) { 593 ti->error = PFX "Error allocating crypto tfm"; 594 goto bad1; 595 } 596 if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) { 597 ti->error = PFX "Expected cipher algorithm"; 598 goto bad2; 599 } 600 601 cc->tfm = tfm; 602 603 /* 604 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>". 605 * See comments at iv code 606 */ 607 608 if (ivmode == NULL) 609 cc->iv_gen_ops = NULL; 610 else if (strcmp(ivmode, "plain") == 0) 611 cc->iv_gen_ops = &crypt_iv_plain_ops; 612 else if (strcmp(ivmode, "essiv") == 0) 613 cc->iv_gen_ops = &crypt_iv_essiv_ops; 614 else { 615 ti->error = PFX "Invalid IV mode"; 616 goto bad2; 617 } 618 619 if (cc->iv_gen_ops && cc->iv_gen_ops->ctr && 620 cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) 621 goto bad2; 622 623 if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv) 624 /* at least a 64 bit sector number should fit in our buffer */ 625 cc->iv_size = max(crypto_tfm_alg_ivsize(tfm), 626 (unsigned int)(sizeof(u64) / sizeof(u8))); 627 else { 628 cc->iv_size = 0; 629 if (cc->iv_gen_ops) { 630 DMWARN(PFX "Selected cipher does not support IVs"); 631 if (cc->iv_gen_ops->dtr) 632 cc->iv_gen_ops->dtr(cc); 633 cc->iv_gen_ops = NULL; 634 } 635 } 636 637 cc->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab, 638 mempool_free_slab, _crypt_io_pool); 639 if (!cc->io_pool) { 640 ti->error = PFX "Cannot allocate crypt io mempool"; 641 goto bad3; 642 } 643 644 cc->page_pool = mempool_create(MIN_POOL_PAGES, mempool_alloc_page, 645 mempool_free_page, NULL); 646 if (!cc->page_pool) { 647 ti->error = PFX "Cannot allocate page mempool"; 648 goto bad4; 649 } 650 651 if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) { 652 ti->error = PFX "Error setting key"; 653 goto bad5; 654 } 655 656 if (sscanf(argv[2], SECTOR_FORMAT, &cc->iv_offset) != 1) { 657 ti->error = PFX "Invalid iv_offset sector"; 658 goto bad5; 659 } 660 661 if (sscanf(argv[4], SECTOR_FORMAT, &cc->start) != 1) { 662 ti->error = PFX "Invalid device sector"; 663 goto bad5; 664 } 665 666 if (dm_get_device(ti, argv[3], cc->start, ti->len, 667 dm_table_get_mode(ti->table), &cc->dev)) { 668 ti->error = PFX "Device lookup failed"; 669 goto bad5; 670 } 671 672 if (ivmode && cc->iv_gen_ops) { 673 if (ivopts) 674 *(ivopts - 1) = ':'; 675 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL); 676 if (!cc->iv_mode) { 677 ti->error = PFX "Error kmallocing iv_mode string"; 678 goto bad5; 679 } 680 strcpy(cc->iv_mode, ivmode); 681 } else 682 cc->iv_mode = NULL; 683 684 ti->private = cc; 685 return 0; 686 687 bad5: 688 mempool_destroy(cc->page_pool); 689 bad4: 690 mempool_destroy(cc->io_pool); 691 bad3: 692 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 693 cc->iv_gen_ops->dtr(cc); 694 bad2: 695 crypto_free_tfm(tfm); 696 bad1: 697 kfree(cc); 698 return -EINVAL; 699 } 700 701 static void crypt_dtr(struct dm_target *ti) 702 { 703 struct crypt_config *cc = (struct crypt_config *) ti->private; 704 705 mempool_destroy(cc->page_pool); 706 mempool_destroy(cc->io_pool); 707 708 kfree(cc->iv_mode); 709 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 710 cc->iv_gen_ops->dtr(cc); 711 crypto_free_tfm(cc->tfm); 712 dm_put_device(ti, cc->dev); 713 kfree(cc); 714 } 715 716 static int crypt_endio(struct bio *bio, unsigned int done, int error) 717 { 718 struct crypt_io *io = (struct crypt_io *) bio->bi_private; 719 struct crypt_config *cc = (struct crypt_config *) io->target->private; 720 721 if (bio_data_dir(bio) == WRITE) { 722 /* 723 * free the processed pages, even if 724 * it's only a partially completed write 725 */ 726 crypt_free_buffer_pages(cc, bio, done); 727 } 728 729 if (bio->bi_size) 730 return 1; 731 732 bio_put(bio); 733 734 /* 735 * successful reads are decrypted by the worker thread 736 */ 737 if ((bio_data_dir(bio) == READ) 738 && bio_flagged(bio, BIO_UPTODATE)) { 739 kcryptd_queue_io(io); 740 return 0; 741 } 742 743 dec_pending(io, error); 744 return error; 745 } 746 747 static inline struct bio * 748 crypt_clone(struct crypt_config *cc, struct crypt_io *io, struct bio *bio, 749 sector_t sector, unsigned int *bvec_idx, 750 struct convert_context *ctx) 751 { 752 struct bio *clone; 753 754 if (bio_data_dir(bio) == WRITE) { 755 clone = crypt_alloc_buffer(cc, bio->bi_size, 756 io->first_clone, bvec_idx); 757 if (clone) { 758 ctx->bio_out = clone; 759 if (crypt_convert(cc, ctx) < 0) { 760 crypt_free_buffer_pages(cc, clone, 761 clone->bi_size); 762 bio_put(clone); 763 return NULL; 764 } 765 } 766 } else { 767 /* 768 * The block layer might modify the bvec array, so always 769 * copy the required bvecs because we need the original 770 * one in order to decrypt the whole bio data *afterwards*. 771 */ 772 clone = bio_alloc(GFP_NOIO, bio_segments(bio)); 773 if (clone) { 774 clone->bi_idx = 0; 775 clone->bi_vcnt = bio_segments(bio); 776 clone->bi_size = bio->bi_size; 777 memcpy(clone->bi_io_vec, bio_iovec(bio), 778 sizeof(struct bio_vec) * clone->bi_vcnt); 779 } 780 } 781 782 if (!clone) 783 return NULL; 784 785 clone->bi_private = io; 786 clone->bi_end_io = crypt_endio; 787 clone->bi_bdev = cc->dev->bdev; 788 clone->bi_sector = cc->start + sector; 789 clone->bi_rw = bio->bi_rw; 790 791 return clone; 792 } 793 794 static int crypt_map(struct dm_target *ti, struct bio *bio, 795 union map_info *map_context) 796 { 797 struct crypt_config *cc = (struct crypt_config *) ti->private; 798 struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO); 799 struct convert_context ctx; 800 struct bio *clone; 801 unsigned int remaining = bio->bi_size; 802 sector_t sector = bio->bi_sector - ti->begin; 803 unsigned int bvec_idx = 0; 804 805 io->target = ti; 806 io->bio = bio; 807 io->first_clone = NULL; 808 io->error = 0; 809 atomic_set(&io->pending, 1); /* hold a reference */ 810 811 if (bio_data_dir(bio) == WRITE) 812 crypt_convert_init(cc, &ctx, NULL, bio, sector, 1); 813 814 /* 815 * The allocated buffers can be smaller than the whole bio, 816 * so repeat the whole process until all the data can be handled. 817 */ 818 while (remaining) { 819 clone = crypt_clone(cc, io, bio, sector, &bvec_idx, &ctx); 820 if (!clone) 821 goto cleanup; 822 823 if (!io->first_clone) { 824 /* 825 * hold a reference to the first clone, because it 826 * holds the bio_vec array and that can't be freed 827 * before all other clones are released 828 */ 829 bio_get(clone); 830 io->first_clone = clone; 831 } 832 atomic_inc(&io->pending); 833 834 remaining -= clone->bi_size; 835 sector += bio_sectors(clone); 836 837 generic_make_request(clone); 838 839 /* out of memory -> run queues */ 840 if (remaining) 841 blk_congestion_wait(bio_data_dir(clone), HZ/100); 842 } 843 844 /* drop reference, clones could have returned before we reach this */ 845 dec_pending(io, 0); 846 return 0; 847 848 cleanup: 849 if (io->first_clone) { 850 dec_pending(io, -ENOMEM); 851 return 0; 852 } 853 854 /* if no bio has been dispatched yet, we can directly return the error */ 855 mempool_free(io, cc->io_pool); 856 return -ENOMEM; 857 } 858 859 static int crypt_status(struct dm_target *ti, status_type_t type, 860 char *result, unsigned int maxlen) 861 { 862 struct crypt_config *cc = (struct crypt_config *) ti->private; 863 const char *cipher; 864 const char *chainmode = NULL; 865 unsigned int sz = 0; 866 867 switch (type) { 868 case STATUSTYPE_INFO: 869 result[0] = '\0'; 870 break; 871 872 case STATUSTYPE_TABLE: 873 cipher = crypto_tfm_alg_name(cc->tfm); 874 875 switch(cc->tfm->crt_cipher.cit_mode) { 876 case CRYPTO_TFM_MODE_CBC: 877 chainmode = "cbc"; 878 break; 879 case CRYPTO_TFM_MODE_ECB: 880 chainmode = "ecb"; 881 break; 882 default: 883 BUG(); 884 } 885 886 if (cc->iv_mode) 887 DMEMIT("%s-%s-%s ", cipher, chainmode, cc->iv_mode); 888 else 889 DMEMIT("%s-%s ", cipher, chainmode); 890 891 if (cc->key_size > 0) { 892 if ((maxlen - sz) < ((cc->key_size << 1) + 1)) 893 return -ENOMEM; 894 895 crypt_encode_key(result + sz, cc->key, cc->key_size); 896 sz += cc->key_size << 1; 897 } else { 898 if (sz >= maxlen) 899 return -ENOMEM; 900 result[sz++] = '-'; 901 } 902 903 DMEMIT(" " SECTOR_FORMAT " %s " SECTOR_FORMAT, 904 cc->iv_offset, cc->dev->name, cc->start); 905 break; 906 } 907 return 0; 908 } 909 910 static struct target_type crypt_target = { 911 .name = "crypt", 912 .version= {1, 1, 0}, 913 .module = THIS_MODULE, 914 .ctr = crypt_ctr, 915 .dtr = crypt_dtr, 916 .map = crypt_map, 917 .status = crypt_status, 918 }; 919 920 static int __init dm_crypt_init(void) 921 { 922 int r; 923 924 _crypt_io_pool = kmem_cache_create("dm-crypt_io", 925 sizeof(struct crypt_io), 926 0, 0, NULL, NULL); 927 if (!_crypt_io_pool) 928 return -ENOMEM; 929 930 _kcryptd_workqueue = create_workqueue("kcryptd"); 931 if (!_kcryptd_workqueue) { 932 r = -ENOMEM; 933 DMERR(PFX "couldn't create kcryptd"); 934 goto bad1; 935 } 936 937 r = dm_register_target(&crypt_target); 938 if (r < 0) { 939 DMERR(PFX "register failed %d", r); 940 goto bad2; 941 } 942 943 return 0; 944 945 bad2: 946 destroy_workqueue(_kcryptd_workqueue); 947 bad1: 948 kmem_cache_destroy(_crypt_io_pool); 949 return r; 950 } 951 952 static void __exit dm_crypt_exit(void) 953 { 954 int r = dm_unregister_target(&crypt_target); 955 956 if (r < 0) 957 DMERR(PFX "unregister failed %d", r); 958 959 destroy_workqueue(_kcryptd_workqueue); 960 kmem_cache_destroy(_crypt_io_pool); 961 } 962 963 module_init(dm_crypt_init); 964 module_exit(dm_crypt_exit); 965 966 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>"); 967 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption"); 968 MODULE_LICENSE("GPL"); 969