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 * Different IV generation algorithms: 98 * 99 * plain: the initial vector is the 32-bit low-endian version of the sector 100 * number, padded with zeros if neccessary. 101 * 102 * ess_iv: "encrypted sector|salt initial vector", the sector number is 103 * encrypted with the bulk cipher using a salt as key. The salt 104 * should be derived from the bulk cipher's key via hashing. 105 * 106 * plumb: unimplemented, see: 107 * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454 108 */ 109 110 static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 111 { 112 memset(iv, 0, cc->iv_size); 113 *(u32 *)iv = cpu_to_le32(sector & 0xffffffff); 114 115 return 0; 116 } 117 118 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, 119 const char *opts) 120 { 121 struct crypto_tfm *essiv_tfm; 122 struct crypto_tfm *hash_tfm; 123 struct scatterlist sg; 124 unsigned int saltsize; 125 u8 *salt; 126 127 if (opts == NULL) { 128 ti->error = PFX "Digest algorithm missing for ESSIV mode"; 129 return -EINVAL; 130 } 131 132 /* Hash the cipher key with the given hash algorithm */ 133 hash_tfm = crypto_alloc_tfm(opts, CRYPTO_TFM_REQ_MAY_SLEEP); 134 if (hash_tfm == NULL) { 135 ti->error = PFX "Error initializing ESSIV hash"; 136 return -EINVAL; 137 } 138 139 if (crypto_tfm_alg_type(hash_tfm) != CRYPTO_ALG_TYPE_DIGEST) { 140 ti->error = PFX "Expected digest algorithm for ESSIV hash"; 141 crypto_free_tfm(hash_tfm); 142 return -EINVAL; 143 } 144 145 saltsize = crypto_tfm_alg_digestsize(hash_tfm); 146 salt = kmalloc(saltsize, GFP_KERNEL); 147 if (salt == NULL) { 148 ti->error = PFX "Error kmallocing salt storage in ESSIV"; 149 crypto_free_tfm(hash_tfm); 150 return -ENOMEM; 151 } 152 153 sg_set_buf(&sg, cc->key, cc->key_size); 154 crypto_digest_digest(hash_tfm, &sg, 1, salt); 155 crypto_free_tfm(hash_tfm); 156 157 /* Setup the essiv_tfm with the given salt */ 158 essiv_tfm = crypto_alloc_tfm(crypto_tfm_alg_name(cc->tfm), 159 CRYPTO_TFM_MODE_ECB | 160 CRYPTO_TFM_REQ_MAY_SLEEP); 161 if (essiv_tfm == NULL) { 162 ti->error = PFX "Error allocating crypto tfm for ESSIV"; 163 kfree(salt); 164 return -EINVAL; 165 } 166 if (crypto_tfm_alg_blocksize(essiv_tfm) 167 != crypto_tfm_alg_ivsize(cc->tfm)) { 168 ti->error = PFX "Block size of ESSIV cipher does " 169 "not match IV size of block cipher"; 170 crypto_free_tfm(essiv_tfm); 171 kfree(salt); 172 return -EINVAL; 173 } 174 if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) { 175 ti->error = PFX "Failed to set key for ESSIV cipher"; 176 crypto_free_tfm(essiv_tfm); 177 kfree(salt); 178 return -EINVAL; 179 } 180 kfree(salt); 181 182 cc->iv_gen_private = (void *)essiv_tfm; 183 return 0; 184 } 185 186 static void crypt_iv_essiv_dtr(struct crypt_config *cc) 187 { 188 crypto_free_tfm((struct crypto_tfm *)cc->iv_gen_private); 189 cc->iv_gen_private = NULL; 190 } 191 192 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector) 193 { 194 struct scatterlist sg; 195 196 memset(iv, 0, cc->iv_size); 197 *(u64 *)iv = cpu_to_le64(sector); 198 199 sg_set_buf(&sg, iv, cc->iv_size); 200 crypto_cipher_encrypt((struct crypto_tfm *)cc->iv_gen_private, 201 &sg, &sg, cc->iv_size); 202 203 return 0; 204 } 205 206 static struct crypt_iv_operations crypt_iv_plain_ops = { 207 .generator = crypt_iv_plain_gen 208 }; 209 210 static struct crypt_iv_operations crypt_iv_essiv_ops = { 211 .ctr = crypt_iv_essiv_ctr, 212 .dtr = crypt_iv_essiv_dtr, 213 .generator = crypt_iv_essiv_gen 214 }; 215 216 217 static int 218 crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out, 219 struct scatterlist *in, unsigned int length, 220 int write, sector_t sector) 221 { 222 u8 iv[cc->iv_size]; 223 int r; 224 225 if (cc->iv_gen_ops) { 226 r = cc->iv_gen_ops->generator(cc, iv, sector); 227 if (r < 0) 228 return r; 229 230 if (write) 231 r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv); 232 else 233 r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv); 234 } else { 235 if (write) 236 r = crypto_cipher_encrypt(cc->tfm, out, in, length); 237 else 238 r = crypto_cipher_decrypt(cc->tfm, out, in, length); 239 } 240 241 return r; 242 } 243 244 static void 245 crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx, 246 struct bio *bio_out, struct bio *bio_in, 247 sector_t sector, int write) 248 { 249 ctx->bio_in = bio_in; 250 ctx->bio_out = bio_out; 251 ctx->offset_in = 0; 252 ctx->offset_out = 0; 253 ctx->idx_in = bio_in ? bio_in->bi_idx : 0; 254 ctx->idx_out = bio_out ? bio_out->bi_idx : 0; 255 ctx->sector = sector + cc->iv_offset; 256 ctx->write = write; 257 } 258 259 /* 260 * Encrypt / decrypt data from one bio to another one (can be the same one) 261 */ 262 static int crypt_convert(struct crypt_config *cc, 263 struct convert_context *ctx) 264 { 265 int r = 0; 266 267 while(ctx->idx_in < ctx->bio_in->bi_vcnt && 268 ctx->idx_out < ctx->bio_out->bi_vcnt) { 269 struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in); 270 struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out); 271 struct scatterlist sg_in = { 272 .page = bv_in->bv_page, 273 .offset = bv_in->bv_offset + ctx->offset_in, 274 .length = 1 << SECTOR_SHIFT 275 }; 276 struct scatterlist sg_out = { 277 .page = bv_out->bv_page, 278 .offset = bv_out->bv_offset + ctx->offset_out, 279 .length = 1 << SECTOR_SHIFT 280 }; 281 282 ctx->offset_in += sg_in.length; 283 if (ctx->offset_in >= bv_in->bv_len) { 284 ctx->offset_in = 0; 285 ctx->idx_in++; 286 } 287 288 ctx->offset_out += sg_out.length; 289 if (ctx->offset_out >= bv_out->bv_len) { 290 ctx->offset_out = 0; 291 ctx->idx_out++; 292 } 293 294 r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length, 295 ctx->write, ctx->sector); 296 if (r < 0) 297 break; 298 299 ctx->sector++; 300 } 301 302 return r; 303 } 304 305 /* 306 * Generate a new unfragmented bio with the given size 307 * This should never violate the device limitations 308 * May return a smaller bio when running out of pages 309 */ 310 static struct bio * 311 crypt_alloc_buffer(struct crypt_config *cc, unsigned int size, 312 struct bio *base_bio, unsigned int *bio_vec_idx) 313 { 314 struct bio *bio; 315 unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 316 gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM; 317 unsigned int i; 318 319 /* 320 * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and 321 * to fail earlier. This is not necessary but increases throughput. 322 * FIXME: Is this really intelligent? 323 */ 324 if (base_bio) 325 bio = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC); 326 else 327 bio = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs); 328 if (!bio) 329 return NULL; 330 331 /* if the last bio was not complete, continue where that one ended */ 332 bio->bi_idx = *bio_vec_idx; 333 bio->bi_vcnt = *bio_vec_idx; 334 bio->bi_size = 0; 335 bio->bi_flags &= ~(1 << BIO_SEG_VALID); 336 337 /* bio->bi_idx pages have already been allocated */ 338 size -= bio->bi_idx * PAGE_SIZE; 339 340 for(i = bio->bi_idx; i < nr_iovecs; i++) { 341 struct bio_vec *bv = bio_iovec_idx(bio, i); 342 343 bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask); 344 if (!bv->bv_page) 345 break; 346 347 /* 348 * if additional pages cannot be allocated without waiting, 349 * return a partially allocated bio, the caller will then try 350 * to allocate additional bios while submitting this partial bio 351 */ 352 if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1)) 353 gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; 354 355 bv->bv_offset = 0; 356 if (size > PAGE_SIZE) 357 bv->bv_len = PAGE_SIZE; 358 else 359 bv->bv_len = size; 360 361 bio->bi_size += bv->bv_len; 362 bio->bi_vcnt++; 363 size -= bv->bv_len; 364 } 365 366 if (!bio->bi_size) { 367 bio_put(bio); 368 return NULL; 369 } 370 371 /* 372 * Remember the last bio_vec allocated to be able 373 * to correctly continue after the splitting. 374 */ 375 *bio_vec_idx = bio->bi_vcnt; 376 377 return bio; 378 } 379 380 static void crypt_free_buffer_pages(struct crypt_config *cc, 381 struct bio *bio, unsigned int bytes) 382 { 383 unsigned int i, start, end; 384 struct bio_vec *bv; 385 386 /* 387 * This is ugly, but Jens Axboe thinks that using bi_idx in the 388 * endio function is too dangerous at the moment, so I calculate the 389 * correct position using bi_vcnt and bi_size. 390 * The bv_offset and bv_len fields might already be modified but we 391 * know that we always allocated whole pages. 392 * A fix to the bi_idx issue in the kernel is in the works, so 393 * we will hopefully be able to revert to the cleaner solution soon. 394 */ 395 i = bio->bi_vcnt - 1; 396 bv = bio_iovec_idx(bio, i); 397 end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size; 398 start = end - bytes; 399 400 start >>= PAGE_SHIFT; 401 if (!bio->bi_size) 402 end = bio->bi_vcnt; 403 else 404 end >>= PAGE_SHIFT; 405 406 for(i = start; i < end; i++) { 407 bv = bio_iovec_idx(bio, i); 408 BUG_ON(!bv->bv_page); 409 mempool_free(bv->bv_page, cc->page_pool); 410 bv->bv_page = NULL; 411 } 412 } 413 414 /* 415 * One of the bios was finished. Check for completion of 416 * the whole request and correctly clean up the buffer. 417 */ 418 static void dec_pending(struct crypt_io *io, int error) 419 { 420 struct crypt_config *cc = (struct crypt_config *) io->target->private; 421 422 if (error < 0) 423 io->error = error; 424 425 if (!atomic_dec_and_test(&io->pending)) 426 return; 427 428 if (io->first_clone) 429 bio_put(io->first_clone); 430 431 bio_endio(io->bio, io->bio->bi_size, io->error); 432 433 mempool_free(io, cc->io_pool); 434 } 435 436 /* 437 * kcryptd: 438 * 439 * Needed because it would be very unwise to do decryption in an 440 * interrupt context, so bios returning from read requests get 441 * queued here. 442 */ 443 static struct workqueue_struct *_kcryptd_workqueue; 444 445 static void kcryptd_do_work(void *data) 446 { 447 struct crypt_io *io = (struct crypt_io *) data; 448 struct crypt_config *cc = (struct crypt_config *) io->target->private; 449 struct convert_context ctx; 450 int r; 451 452 crypt_convert_init(cc, &ctx, io->bio, io->bio, 453 io->bio->bi_sector - io->target->begin, 0); 454 r = crypt_convert(cc, &ctx); 455 456 dec_pending(io, r); 457 } 458 459 static void kcryptd_queue_io(struct crypt_io *io) 460 { 461 INIT_WORK(&io->work, kcryptd_do_work, io); 462 queue_work(_kcryptd_workqueue, &io->work); 463 } 464 465 /* 466 * Decode key from its hex representation 467 */ 468 static int crypt_decode_key(u8 *key, char *hex, unsigned int size) 469 { 470 char buffer[3]; 471 char *endp; 472 unsigned int i; 473 474 buffer[2] = '\0'; 475 476 for(i = 0; i < size; i++) { 477 buffer[0] = *hex++; 478 buffer[1] = *hex++; 479 480 key[i] = (u8)simple_strtoul(buffer, &endp, 16); 481 482 if (endp != &buffer[2]) 483 return -EINVAL; 484 } 485 486 if (*hex != '\0') 487 return -EINVAL; 488 489 return 0; 490 } 491 492 /* 493 * Encode key into its hex representation 494 */ 495 static void crypt_encode_key(char *hex, u8 *key, unsigned int size) 496 { 497 unsigned int i; 498 499 for(i = 0; i < size; i++) { 500 sprintf(hex, "%02x", *key); 501 hex += 2; 502 key++; 503 } 504 } 505 506 /* 507 * Construct an encryption mapping: 508 * <cipher> <key> <iv_offset> <dev_path> <start> 509 */ 510 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) 511 { 512 struct crypt_config *cc; 513 struct crypto_tfm *tfm; 514 char *tmp; 515 char *cipher; 516 char *chainmode; 517 char *ivmode; 518 char *ivopts; 519 unsigned int crypto_flags; 520 unsigned int key_size; 521 unsigned long long tmpll; 522 523 if (argc != 5) { 524 ti->error = PFX "Not enough arguments"; 525 return -EINVAL; 526 } 527 528 tmp = argv[0]; 529 cipher = strsep(&tmp, "-"); 530 chainmode = strsep(&tmp, "-"); 531 ivopts = strsep(&tmp, "-"); 532 ivmode = strsep(&ivopts, ":"); 533 534 if (tmp) 535 DMWARN(PFX "Unexpected additional cipher options"); 536 537 key_size = strlen(argv[1]) >> 1; 538 539 cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL); 540 if (cc == NULL) { 541 ti->error = 542 PFX "Cannot allocate transparent encryption context"; 543 return -ENOMEM; 544 } 545 546 cc->key_size = key_size; 547 if ((!key_size && strcmp(argv[1], "-") != 0) || 548 (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) { 549 ti->error = PFX "Error decoding key"; 550 goto bad1; 551 } 552 553 /* Compatiblity mode for old dm-crypt cipher strings */ 554 if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) { 555 chainmode = "cbc"; 556 ivmode = "plain"; 557 } 558 559 /* Choose crypto_flags according to chainmode */ 560 if (strcmp(chainmode, "cbc") == 0) 561 crypto_flags = CRYPTO_TFM_MODE_CBC; 562 else if (strcmp(chainmode, "ecb") == 0) 563 crypto_flags = CRYPTO_TFM_MODE_ECB; 564 else { 565 ti->error = PFX "Unknown chaining mode"; 566 goto bad1; 567 } 568 569 if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) { 570 ti->error = PFX "This chaining mode requires an IV mechanism"; 571 goto bad1; 572 } 573 574 tfm = crypto_alloc_tfm(cipher, crypto_flags | CRYPTO_TFM_REQ_MAY_SLEEP); 575 if (!tfm) { 576 ti->error = PFX "Error allocating crypto tfm"; 577 goto bad1; 578 } 579 if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) { 580 ti->error = PFX "Expected cipher algorithm"; 581 goto bad2; 582 } 583 584 cc->tfm = tfm; 585 586 /* 587 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>". 588 * See comments at iv code 589 */ 590 591 if (ivmode == NULL) 592 cc->iv_gen_ops = NULL; 593 else if (strcmp(ivmode, "plain") == 0) 594 cc->iv_gen_ops = &crypt_iv_plain_ops; 595 else if (strcmp(ivmode, "essiv") == 0) 596 cc->iv_gen_ops = &crypt_iv_essiv_ops; 597 else { 598 ti->error = PFX "Invalid IV mode"; 599 goto bad2; 600 } 601 602 if (cc->iv_gen_ops && cc->iv_gen_ops->ctr && 603 cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) 604 goto bad2; 605 606 if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv) 607 /* at least a 64 bit sector number should fit in our buffer */ 608 cc->iv_size = max(crypto_tfm_alg_ivsize(tfm), 609 (unsigned int)(sizeof(u64) / sizeof(u8))); 610 else { 611 cc->iv_size = 0; 612 if (cc->iv_gen_ops) { 613 DMWARN(PFX "Selected cipher does not support IVs"); 614 if (cc->iv_gen_ops->dtr) 615 cc->iv_gen_ops->dtr(cc); 616 cc->iv_gen_ops = NULL; 617 } 618 } 619 620 cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool); 621 if (!cc->io_pool) { 622 ti->error = PFX "Cannot allocate crypt io mempool"; 623 goto bad3; 624 } 625 626 cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0); 627 if (!cc->page_pool) { 628 ti->error = PFX "Cannot allocate page mempool"; 629 goto bad4; 630 } 631 632 if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) { 633 ti->error = PFX "Error setting key"; 634 goto bad5; 635 } 636 637 if (sscanf(argv[2], "%llu", &tmpll) != 1) { 638 ti->error = PFX "Invalid iv_offset sector"; 639 goto bad5; 640 } 641 cc->iv_offset = tmpll; 642 643 if (sscanf(argv[4], "%llu", &tmpll) != 1) { 644 ti->error = PFX "Invalid device sector"; 645 goto bad5; 646 } 647 cc->start = tmpll; 648 649 if (dm_get_device(ti, argv[3], cc->start, ti->len, 650 dm_table_get_mode(ti->table), &cc->dev)) { 651 ti->error = PFX "Device lookup failed"; 652 goto bad5; 653 } 654 655 if (ivmode && cc->iv_gen_ops) { 656 if (ivopts) 657 *(ivopts - 1) = ':'; 658 cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL); 659 if (!cc->iv_mode) { 660 ti->error = PFX "Error kmallocing iv_mode string"; 661 goto bad5; 662 } 663 strcpy(cc->iv_mode, ivmode); 664 } else 665 cc->iv_mode = NULL; 666 667 ti->private = cc; 668 return 0; 669 670 bad5: 671 mempool_destroy(cc->page_pool); 672 bad4: 673 mempool_destroy(cc->io_pool); 674 bad3: 675 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 676 cc->iv_gen_ops->dtr(cc); 677 bad2: 678 crypto_free_tfm(tfm); 679 bad1: 680 /* Must zero key material before freeing */ 681 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 682 kfree(cc); 683 return -EINVAL; 684 } 685 686 static void crypt_dtr(struct dm_target *ti) 687 { 688 struct crypt_config *cc = (struct crypt_config *) ti->private; 689 690 mempool_destroy(cc->page_pool); 691 mempool_destroy(cc->io_pool); 692 693 kfree(cc->iv_mode); 694 if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) 695 cc->iv_gen_ops->dtr(cc); 696 crypto_free_tfm(cc->tfm); 697 dm_put_device(ti, cc->dev); 698 699 /* Must zero key material before freeing */ 700 memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8)); 701 kfree(cc); 702 } 703 704 static int crypt_endio(struct bio *bio, unsigned int done, int error) 705 { 706 struct crypt_io *io = (struct crypt_io *) bio->bi_private; 707 struct crypt_config *cc = (struct crypt_config *) io->target->private; 708 709 if (bio_data_dir(bio) == WRITE) { 710 /* 711 * free the processed pages, even if 712 * it's only a partially completed write 713 */ 714 crypt_free_buffer_pages(cc, bio, done); 715 } 716 717 if (bio->bi_size) 718 return 1; 719 720 bio_put(bio); 721 722 /* 723 * successful reads are decrypted by the worker thread 724 */ 725 if ((bio_data_dir(bio) == READ) 726 && bio_flagged(bio, BIO_UPTODATE)) { 727 kcryptd_queue_io(io); 728 return 0; 729 } 730 731 dec_pending(io, error); 732 return error; 733 } 734 735 static inline struct bio * 736 crypt_clone(struct crypt_config *cc, struct crypt_io *io, struct bio *bio, 737 sector_t sector, unsigned int *bvec_idx, 738 struct convert_context *ctx) 739 { 740 struct bio *clone; 741 742 if (bio_data_dir(bio) == WRITE) { 743 clone = crypt_alloc_buffer(cc, bio->bi_size, 744 io->first_clone, bvec_idx); 745 if (clone) { 746 ctx->bio_out = clone; 747 if (crypt_convert(cc, ctx) < 0) { 748 crypt_free_buffer_pages(cc, clone, 749 clone->bi_size); 750 bio_put(clone); 751 return NULL; 752 } 753 } 754 } else { 755 /* 756 * The block layer might modify the bvec array, so always 757 * copy the required bvecs because we need the original 758 * one in order to decrypt the whole bio data *afterwards*. 759 */ 760 clone = bio_alloc(GFP_NOIO, bio_segments(bio)); 761 if (clone) { 762 clone->bi_idx = 0; 763 clone->bi_vcnt = bio_segments(bio); 764 clone->bi_size = bio->bi_size; 765 memcpy(clone->bi_io_vec, bio_iovec(bio), 766 sizeof(struct bio_vec) * clone->bi_vcnt); 767 } 768 } 769 770 if (!clone) 771 return NULL; 772 773 clone->bi_private = io; 774 clone->bi_end_io = crypt_endio; 775 clone->bi_bdev = cc->dev->bdev; 776 clone->bi_sector = cc->start + sector; 777 clone->bi_rw = bio->bi_rw; 778 779 return clone; 780 } 781 782 static int crypt_map(struct dm_target *ti, struct bio *bio, 783 union map_info *map_context) 784 { 785 struct crypt_config *cc = (struct crypt_config *) ti->private; 786 struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO); 787 struct convert_context ctx; 788 struct bio *clone; 789 unsigned int remaining = bio->bi_size; 790 sector_t sector = bio->bi_sector - ti->begin; 791 unsigned int bvec_idx = 0; 792 793 io->target = ti; 794 io->bio = bio; 795 io->first_clone = NULL; 796 io->error = 0; 797 atomic_set(&io->pending, 1); /* hold a reference */ 798 799 if (bio_data_dir(bio) == WRITE) 800 crypt_convert_init(cc, &ctx, NULL, bio, sector, 1); 801 802 /* 803 * The allocated buffers can be smaller than the whole bio, 804 * so repeat the whole process until all the data can be handled. 805 */ 806 while (remaining) { 807 clone = crypt_clone(cc, io, bio, sector, &bvec_idx, &ctx); 808 if (!clone) 809 goto cleanup; 810 811 if (!io->first_clone) { 812 /* 813 * hold a reference to the first clone, because it 814 * holds the bio_vec array and that can't be freed 815 * before all other clones are released 816 */ 817 bio_get(clone); 818 io->first_clone = clone; 819 } 820 atomic_inc(&io->pending); 821 822 remaining -= clone->bi_size; 823 sector += bio_sectors(clone); 824 825 generic_make_request(clone); 826 827 /* out of memory -> run queues */ 828 if (remaining) 829 blk_congestion_wait(bio_data_dir(clone), HZ/100); 830 } 831 832 /* drop reference, clones could have returned before we reach this */ 833 dec_pending(io, 0); 834 return 0; 835 836 cleanup: 837 if (io->first_clone) { 838 dec_pending(io, -ENOMEM); 839 return 0; 840 } 841 842 /* if no bio has been dispatched yet, we can directly return the error */ 843 mempool_free(io, cc->io_pool); 844 return -ENOMEM; 845 } 846 847 static int crypt_status(struct dm_target *ti, status_type_t type, 848 char *result, unsigned int maxlen) 849 { 850 struct crypt_config *cc = (struct crypt_config *) ti->private; 851 const char *cipher; 852 const char *chainmode = NULL; 853 unsigned int sz = 0; 854 855 switch (type) { 856 case STATUSTYPE_INFO: 857 result[0] = '\0'; 858 break; 859 860 case STATUSTYPE_TABLE: 861 cipher = crypto_tfm_alg_name(cc->tfm); 862 863 switch(cc->tfm->crt_cipher.cit_mode) { 864 case CRYPTO_TFM_MODE_CBC: 865 chainmode = "cbc"; 866 break; 867 case CRYPTO_TFM_MODE_ECB: 868 chainmode = "ecb"; 869 break; 870 default: 871 BUG(); 872 } 873 874 if (cc->iv_mode) 875 DMEMIT("%s-%s-%s ", cipher, chainmode, cc->iv_mode); 876 else 877 DMEMIT("%s-%s ", cipher, chainmode); 878 879 if (cc->key_size > 0) { 880 if ((maxlen - sz) < ((cc->key_size << 1) + 1)) 881 return -ENOMEM; 882 883 crypt_encode_key(result + sz, cc->key, cc->key_size); 884 sz += cc->key_size << 1; 885 } else { 886 if (sz >= maxlen) 887 return -ENOMEM; 888 result[sz++] = '-'; 889 } 890 891 DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset, 892 cc->dev->name, (unsigned long long)cc->start); 893 break; 894 } 895 return 0; 896 } 897 898 static struct target_type crypt_target = { 899 .name = "crypt", 900 .version= {1, 1, 0}, 901 .module = THIS_MODULE, 902 .ctr = crypt_ctr, 903 .dtr = crypt_dtr, 904 .map = crypt_map, 905 .status = crypt_status, 906 }; 907 908 static int __init dm_crypt_init(void) 909 { 910 int r; 911 912 _crypt_io_pool = kmem_cache_create("dm-crypt_io", 913 sizeof(struct crypt_io), 914 0, 0, NULL, NULL); 915 if (!_crypt_io_pool) 916 return -ENOMEM; 917 918 _kcryptd_workqueue = create_workqueue("kcryptd"); 919 if (!_kcryptd_workqueue) { 920 r = -ENOMEM; 921 DMERR(PFX "couldn't create kcryptd"); 922 goto bad1; 923 } 924 925 r = dm_register_target(&crypt_target); 926 if (r < 0) { 927 DMERR(PFX "register failed %d", r); 928 goto bad2; 929 } 930 931 return 0; 932 933 bad2: 934 destroy_workqueue(_kcryptd_workqueue); 935 bad1: 936 kmem_cache_destroy(_crypt_io_pool); 937 return r; 938 } 939 940 static void __exit dm_crypt_exit(void) 941 { 942 int r = dm_unregister_target(&crypt_target); 943 944 if (r < 0) 945 DMERR(PFX "unregister failed %d", r); 946 947 destroy_workqueue(_kcryptd_workqueue); 948 kmem_cache_destroy(_crypt_io_pool); 949 } 950 951 module_init(dm_crypt_init); 952 module_exit(dm_crypt_exit); 953 954 MODULE_AUTHOR("Christophe Saout <christophe@saout.de>"); 955 MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption"); 956 MODULE_LICENSE("GPL"); 957