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