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