Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2003 Christophe Saout <christophe@saout.de> |
| 3 | * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org> |
| 4 | * |
| 5 | * This file is released under the GPL. |
| 6 | */ |
| 7 | |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/init.h> |
| 10 | #include <linux/kernel.h> |
| 11 | #include <linux/bio.h> |
| 12 | #include <linux/blkdev.h> |
| 13 | #include <linux/mempool.h> |
| 14 | #include <linux/slab.h> |
| 15 | #include <linux/crypto.h> |
| 16 | #include <linux/workqueue.h> |
| 17 | #include <asm/atomic.h> |
| 18 | #include <asm/scatterlist.h> |
| 19 | #include <asm/page.h> |
| 20 | |
| 21 | #include "dm.h" |
| 22 | |
| 23 | #define PFX "crypt: " |
| 24 | |
| 25 | /* |
| 26 | * per bio private data |
| 27 | */ |
| 28 | struct crypt_io { |
| 29 | struct dm_target *target; |
| 30 | struct bio *bio; |
| 31 | struct bio *first_clone; |
| 32 | struct work_struct work; |
| 33 | atomic_t pending; |
| 34 | int error; |
| 35 | }; |
| 36 | |
| 37 | /* |
| 38 | * context holding the current state of a multi-part conversion |
| 39 | */ |
| 40 | struct convert_context { |
| 41 | struct bio *bio_in; |
| 42 | struct bio *bio_out; |
| 43 | unsigned int offset_in; |
| 44 | unsigned int offset_out; |
| 45 | unsigned int idx_in; |
| 46 | unsigned int idx_out; |
| 47 | sector_t sector; |
| 48 | int write; |
| 49 | }; |
| 50 | |
| 51 | struct crypt_config; |
| 52 | |
| 53 | struct crypt_iv_operations { |
| 54 | int (*ctr)(struct crypt_config *cc, struct dm_target *ti, |
| 55 | const char *opts); |
| 56 | void (*dtr)(struct crypt_config *cc); |
| 57 | const char *(*status)(struct crypt_config *cc); |
| 58 | int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector); |
| 59 | }; |
| 60 | |
| 61 | /* |
| 62 | * Crypt: maps a linear range of a block device |
| 63 | * and encrypts / decrypts at the same time. |
| 64 | */ |
| 65 | struct crypt_config { |
| 66 | struct dm_dev *dev; |
| 67 | sector_t start; |
| 68 | |
| 69 | /* |
| 70 | * pool for per bio private data and |
| 71 | * for encryption buffer pages |
| 72 | */ |
| 73 | mempool_t *io_pool; |
| 74 | mempool_t *page_pool; |
| 75 | |
| 76 | /* |
| 77 | * crypto related data |
| 78 | */ |
| 79 | struct crypt_iv_operations *iv_gen_ops; |
| 80 | char *iv_mode; |
| 81 | void *iv_gen_private; |
| 82 | sector_t iv_offset; |
| 83 | unsigned int iv_size; |
| 84 | |
| 85 | struct crypto_tfm *tfm; |
| 86 | unsigned int key_size; |
| 87 | u8 key[0]; |
| 88 | }; |
| 89 | |
| 90 | #define MIN_IOS 256 |
| 91 | #define MIN_POOL_PAGES 32 |
| 92 | #define MIN_BIO_PAGES 8 |
| 93 | |
| 94 | static kmem_cache_t *_crypt_io_pool; |
| 95 | |
| 96 | /* |
| 97 | * Mempool alloc and free functions for the page |
| 98 | */ |
| 99 | static void *mempool_alloc_page(unsigned int __nocast gfp_mask, void *data) |
| 100 | { |
| 101 | return alloc_page(gfp_mask); |
| 102 | } |
| 103 | |
| 104 | static void mempool_free_page(void *page, void *data) |
| 105 | { |
| 106 | __free_page(page); |
| 107 | } |
| 108 | |
| 109 | |
| 110 | /* |
| 111 | * Different IV generation algorithms: |
| 112 | * |
| 113 | * plain: the initial vector is the 32-bit low-endian version of the sector |
| 114 | * number, padded with zeros if neccessary. |
| 115 | * |
| 116 | * ess_iv: "encrypted sector|salt initial vector", the sector number is |
| 117 | * encrypted with the bulk cipher using a salt as key. The salt |
| 118 | * should be derived from the bulk cipher's key via hashing. |
| 119 | * |
| 120 | * plumb: unimplemented, see: |
| 121 | * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454 |
| 122 | */ |
| 123 | |
| 124 | static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector) |
| 125 | { |
| 126 | memset(iv, 0, cc->iv_size); |
| 127 | *(u32 *)iv = cpu_to_le32(sector & 0xffffffff); |
| 128 | |
| 129 | return 0; |
| 130 | } |
| 131 | |
| 132 | static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti, |
| 133 | const char *opts) |
| 134 | { |
| 135 | struct crypto_tfm *essiv_tfm; |
| 136 | struct crypto_tfm *hash_tfm; |
| 137 | struct scatterlist sg; |
| 138 | unsigned int saltsize; |
| 139 | u8 *salt; |
| 140 | |
| 141 | if (opts == NULL) { |
| 142 | ti->error = PFX "Digest algorithm missing for ESSIV mode"; |
| 143 | return -EINVAL; |
| 144 | } |
| 145 | |
| 146 | /* Hash the cipher key with the given hash algorithm */ |
| 147 | hash_tfm = crypto_alloc_tfm(opts, 0); |
| 148 | if (hash_tfm == NULL) { |
| 149 | ti->error = PFX "Error initializing ESSIV hash"; |
| 150 | return -EINVAL; |
| 151 | } |
| 152 | |
| 153 | if (crypto_tfm_alg_type(hash_tfm) != CRYPTO_ALG_TYPE_DIGEST) { |
| 154 | ti->error = PFX "Expected digest algorithm for ESSIV hash"; |
| 155 | crypto_free_tfm(hash_tfm); |
| 156 | return -EINVAL; |
| 157 | } |
| 158 | |
| 159 | saltsize = crypto_tfm_alg_digestsize(hash_tfm); |
| 160 | salt = kmalloc(saltsize, GFP_KERNEL); |
| 161 | if (salt == NULL) { |
| 162 | ti->error = PFX "Error kmallocing salt storage in ESSIV"; |
| 163 | crypto_free_tfm(hash_tfm); |
| 164 | return -ENOMEM; |
| 165 | } |
| 166 | |
| 167 | sg.page = virt_to_page(cc->key); |
| 168 | sg.offset = offset_in_page(cc->key); |
| 169 | sg.length = cc->key_size; |
| 170 | crypto_digest_digest(hash_tfm, &sg, 1, salt); |
| 171 | crypto_free_tfm(hash_tfm); |
| 172 | |
| 173 | /* Setup the essiv_tfm with the given salt */ |
| 174 | essiv_tfm = crypto_alloc_tfm(crypto_tfm_alg_name(cc->tfm), |
| 175 | CRYPTO_TFM_MODE_ECB); |
| 176 | if (essiv_tfm == NULL) { |
| 177 | ti->error = PFX "Error allocating crypto tfm for ESSIV"; |
| 178 | kfree(salt); |
| 179 | return -EINVAL; |
| 180 | } |
| 181 | if (crypto_tfm_alg_blocksize(essiv_tfm) |
| 182 | != crypto_tfm_alg_ivsize(cc->tfm)) { |
| 183 | ti->error = PFX "Block size of ESSIV cipher does " |
| 184 | "not match IV size of block cipher"; |
| 185 | crypto_free_tfm(essiv_tfm); |
| 186 | kfree(salt); |
| 187 | return -EINVAL; |
| 188 | } |
| 189 | if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) { |
| 190 | ti->error = PFX "Failed to set key for ESSIV cipher"; |
| 191 | crypto_free_tfm(essiv_tfm); |
| 192 | kfree(salt); |
| 193 | return -EINVAL; |
| 194 | } |
| 195 | kfree(salt); |
| 196 | |
| 197 | cc->iv_gen_private = (void *)essiv_tfm; |
| 198 | return 0; |
| 199 | } |
| 200 | |
| 201 | static void crypt_iv_essiv_dtr(struct crypt_config *cc) |
| 202 | { |
| 203 | crypto_free_tfm((struct crypto_tfm *)cc->iv_gen_private); |
| 204 | cc->iv_gen_private = NULL; |
| 205 | } |
| 206 | |
| 207 | static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector) |
| 208 | { |
| 209 | struct scatterlist sg = { NULL, }; |
| 210 | |
| 211 | memset(iv, 0, cc->iv_size); |
| 212 | *(u64 *)iv = cpu_to_le64(sector); |
| 213 | |
| 214 | sg.page = virt_to_page(iv); |
| 215 | sg.offset = offset_in_page(iv); |
| 216 | sg.length = cc->iv_size; |
| 217 | crypto_cipher_encrypt((struct crypto_tfm *)cc->iv_gen_private, |
| 218 | &sg, &sg, cc->iv_size); |
| 219 | |
| 220 | return 0; |
| 221 | } |
| 222 | |
| 223 | static struct crypt_iv_operations crypt_iv_plain_ops = { |
| 224 | .generator = crypt_iv_plain_gen |
| 225 | }; |
| 226 | |
| 227 | static struct crypt_iv_operations crypt_iv_essiv_ops = { |
| 228 | .ctr = crypt_iv_essiv_ctr, |
| 229 | .dtr = crypt_iv_essiv_dtr, |
| 230 | .generator = crypt_iv_essiv_gen |
| 231 | }; |
| 232 | |
| 233 | |
| 234 | static inline int |
| 235 | crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out, |
| 236 | struct scatterlist *in, unsigned int length, |
| 237 | int write, sector_t sector) |
| 238 | { |
| 239 | u8 iv[cc->iv_size]; |
| 240 | int r; |
| 241 | |
| 242 | if (cc->iv_gen_ops) { |
| 243 | r = cc->iv_gen_ops->generator(cc, iv, sector); |
| 244 | if (r < 0) |
| 245 | return r; |
| 246 | |
| 247 | if (write) |
| 248 | r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv); |
| 249 | else |
| 250 | r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv); |
| 251 | } else { |
| 252 | if (write) |
| 253 | r = crypto_cipher_encrypt(cc->tfm, out, in, length); |
| 254 | else |
| 255 | r = crypto_cipher_decrypt(cc->tfm, out, in, length); |
| 256 | } |
| 257 | |
| 258 | return r; |
| 259 | } |
| 260 | |
| 261 | static void |
| 262 | crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx, |
| 263 | struct bio *bio_out, struct bio *bio_in, |
| 264 | sector_t sector, int write) |
| 265 | { |
| 266 | ctx->bio_in = bio_in; |
| 267 | ctx->bio_out = bio_out; |
| 268 | ctx->offset_in = 0; |
| 269 | ctx->offset_out = 0; |
| 270 | ctx->idx_in = bio_in ? bio_in->bi_idx : 0; |
| 271 | ctx->idx_out = bio_out ? bio_out->bi_idx : 0; |
| 272 | ctx->sector = sector + cc->iv_offset; |
| 273 | ctx->write = write; |
| 274 | } |
| 275 | |
| 276 | /* |
| 277 | * Encrypt / decrypt data from one bio to another one (can be the same one) |
| 278 | */ |
| 279 | static int crypt_convert(struct crypt_config *cc, |
| 280 | struct convert_context *ctx) |
| 281 | { |
| 282 | int r = 0; |
| 283 | |
| 284 | while(ctx->idx_in < ctx->bio_in->bi_vcnt && |
| 285 | ctx->idx_out < ctx->bio_out->bi_vcnt) { |
| 286 | struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in); |
| 287 | struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out); |
| 288 | struct scatterlist sg_in = { |
| 289 | .page = bv_in->bv_page, |
| 290 | .offset = bv_in->bv_offset + ctx->offset_in, |
| 291 | .length = 1 << SECTOR_SHIFT |
| 292 | }; |
| 293 | struct scatterlist sg_out = { |
| 294 | .page = bv_out->bv_page, |
| 295 | .offset = bv_out->bv_offset + ctx->offset_out, |
| 296 | .length = 1 << SECTOR_SHIFT |
| 297 | }; |
| 298 | |
| 299 | ctx->offset_in += sg_in.length; |
| 300 | if (ctx->offset_in >= bv_in->bv_len) { |
| 301 | ctx->offset_in = 0; |
| 302 | ctx->idx_in++; |
| 303 | } |
| 304 | |
| 305 | ctx->offset_out += sg_out.length; |
| 306 | if (ctx->offset_out >= bv_out->bv_len) { |
| 307 | ctx->offset_out = 0; |
| 308 | ctx->idx_out++; |
| 309 | } |
| 310 | |
| 311 | r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length, |
| 312 | ctx->write, ctx->sector); |
| 313 | if (r < 0) |
| 314 | break; |
| 315 | |
| 316 | ctx->sector++; |
| 317 | } |
| 318 | |
| 319 | return r; |
| 320 | } |
| 321 | |
| 322 | /* |
| 323 | * Generate a new unfragmented bio with the given size |
| 324 | * This should never violate the device limitations |
| 325 | * May return a smaller bio when running out of pages |
| 326 | */ |
| 327 | static struct bio * |
| 328 | crypt_alloc_buffer(struct crypt_config *cc, unsigned int size, |
| 329 | struct bio *base_bio, unsigned int *bio_vec_idx) |
| 330 | { |
| 331 | struct bio *bio; |
| 332 | unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| 333 | int gfp_mask = GFP_NOIO | __GFP_HIGHMEM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 334 | unsigned int i; |
| 335 | |
| 336 | /* |
Nick Piggin | bd53b71 | 2005-05-01 08:58:37 -0700 | [diff] [blame] | 337 | * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and |
| 338 | * to fail earlier. This is not necessary but increases throughput. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 339 | * FIXME: Is this really intelligent? |
| 340 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 341 | if (base_bio) |
Nick Piggin | bd53b71 | 2005-05-01 08:58:37 -0700 | [diff] [blame] | 342 | bio = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 343 | else |
Nick Piggin | bd53b71 | 2005-05-01 08:58:37 -0700 | [diff] [blame] | 344 | bio = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs); |
| 345 | if (!bio) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 346 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 347 | |
| 348 | /* if the last bio was not complete, continue where that one ended */ |
| 349 | bio->bi_idx = *bio_vec_idx; |
| 350 | bio->bi_vcnt = *bio_vec_idx; |
| 351 | bio->bi_size = 0; |
| 352 | bio->bi_flags &= ~(1 << BIO_SEG_VALID); |
| 353 | |
| 354 | /* bio->bi_idx pages have already been allocated */ |
| 355 | size -= bio->bi_idx * PAGE_SIZE; |
| 356 | |
| 357 | for(i = bio->bi_idx; i < nr_iovecs; i++) { |
| 358 | struct bio_vec *bv = bio_iovec_idx(bio, i); |
| 359 | |
| 360 | bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask); |
| 361 | if (!bv->bv_page) |
| 362 | break; |
| 363 | |
| 364 | /* |
| 365 | * if additional pages cannot be allocated without waiting, |
| 366 | * return a partially allocated bio, the caller will then try |
| 367 | * to allocate additional bios while submitting this partial bio |
| 368 | */ |
| 369 | if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1)) |
| 370 | gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; |
| 371 | |
| 372 | bv->bv_offset = 0; |
| 373 | if (size > PAGE_SIZE) |
| 374 | bv->bv_len = PAGE_SIZE; |
| 375 | else |
| 376 | bv->bv_len = size; |
| 377 | |
| 378 | bio->bi_size += bv->bv_len; |
| 379 | bio->bi_vcnt++; |
| 380 | size -= bv->bv_len; |
| 381 | } |
| 382 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 383 | if (!bio->bi_size) { |
| 384 | bio_put(bio); |
| 385 | return NULL; |
| 386 | } |
| 387 | |
| 388 | /* |
| 389 | * Remember the last bio_vec allocated to be able |
| 390 | * to correctly continue after the splitting. |
| 391 | */ |
| 392 | *bio_vec_idx = bio->bi_vcnt; |
| 393 | |
| 394 | return bio; |
| 395 | } |
| 396 | |
| 397 | static void crypt_free_buffer_pages(struct crypt_config *cc, |
| 398 | struct bio *bio, unsigned int bytes) |
| 399 | { |
| 400 | unsigned int i, start, end; |
| 401 | struct bio_vec *bv; |
| 402 | |
| 403 | /* |
| 404 | * This is ugly, but Jens Axboe thinks that using bi_idx in the |
| 405 | * endio function is too dangerous at the moment, so I calculate the |
| 406 | * correct position using bi_vcnt and bi_size. |
| 407 | * The bv_offset and bv_len fields might already be modified but we |
| 408 | * know that we always allocated whole pages. |
| 409 | * A fix to the bi_idx issue in the kernel is in the works, so |
| 410 | * we will hopefully be able to revert to the cleaner solution soon. |
| 411 | */ |
| 412 | i = bio->bi_vcnt - 1; |
| 413 | bv = bio_iovec_idx(bio, i); |
| 414 | end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size; |
| 415 | start = end - bytes; |
| 416 | |
| 417 | start >>= PAGE_SHIFT; |
| 418 | if (!bio->bi_size) |
| 419 | end = bio->bi_vcnt; |
| 420 | else |
| 421 | end >>= PAGE_SHIFT; |
| 422 | |
| 423 | for(i = start; i < end; i++) { |
| 424 | bv = bio_iovec_idx(bio, i); |
| 425 | BUG_ON(!bv->bv_page); |
| 426 | mempool_free(bv->bv_page, cc->page_pool); |
| 427 | bv->bv_page = NULL; |
| 428 | } |
| 429 | } |
| 430 | |
| 431 | /* |
| 432 | * One of the bios was finished. Check for completion of |
| 433 | * the whole request and correctly clean up the buffer. |
| 434 | */ |
| 435 | static void dec_pending(struct crypt_io *io, int error) |
| 436 | { |
| 437 | struct crypt_config *cc = (struct crypt_config *) io->target->private; |
| 438 | |
| 439 | if (error < 0) |
| 440 | io->error = error; |
| 441 | |
| 442 | if (!atomic_dec_and_test(&io->pending)) |
| 443 | return; |
| 444 | |
| 445 | if (io->first_clone) |
| 446 | bio_put(io->first_clone); |
| 447 | |
| 448 | bio_endio(io->bio, io->bio->bi_size, io->error); |
| 449 | |
| 450 | mempool_free(io, cc->io_pool); |
| 451 | } |
| 452 | |
| 453 | /* |
| 454 | * kcryptd: |
| 455 | * |
| 456 | * Needed because it would be very unwise to do decryption in an |
| 457 | * interrupt context, so bios returning from read requests get |
| 458 | * queued here. |
| 459 | */ |
| 460 | static struct workqueue_struct *_kcryptd_workqueue; |
| 461 | |
| 462 | static void kcryptd_do_work(void *data) |
| 463 | { |
| 464 | struct crypt_io *io = (struct crypt_io *) data; |
| 465 | struct crypt_config *cc = (struct crypt_config *) io->target->private; |
| 466 | struct convert_context ctx; |
| 467 | int r; |
| 468 | |
| 469 | crypt_convert_init(cc, &ctx, io->bio, io->bio, |
| 470 | io->bio->bi_sector - io->target->begin, 0); |
| 471 | r = crypt_convert(cc, &ctx); |
| 472 | |
| 473 | dec_pending(io, r); |
| 474 | } |
| 475 | |
| 476 | static void kcryptd_queue_io(struct crypt_io *io) |
| 477 | { |
| 478 | INIT_WORK(&io->work, kcryptd_do_work, io); |
| 479 | queue_work(_kcryptd_workqueue, &io->work); |
| 480 | } |
| 481 | |
| 482 | /* |
| 483 | * Decode key from its hex representation |
| 484 | */ |
| 485 | static int crypt_decode_key(u8 *key, char *hex, unsigned int size) |
| 486 | { |
| 487 | char buffer[3]; |
| 488 | char *endp; |
| 489 | unsigned int i; |
| 490 | |
| 491 | buffer[2] = '\0'; |
| 492 | |
| 493 | for(i = 0; i < size; i++) { |
| 494 | buffer[0] = *hex++; |
| 495 | buffer[1] = *hex++; |
| 496 | |
| 497 | key[i] = (u8)simple_strtoul(buffer, &endp, 16); |
| 498 | |
| 499 | if (endp != &buffer[2]) |
| 500 | return -EINVAL; |
| 501 | } |
| 502 | |
| 503 | if (*hex != '\0') |
| 504 | return -EINVAL; |
| 505 | |
| 506 | return 0; |
| 507 | } |
| 508 | |
| 509 | /* |
| 510 | * Encode key into its hex representation |
| 511 | */ |
| 512 | static void crypt_encode_key(char *hex, u8 *key, unsigned int size) |
| 513 | { |
| 514 | unsigned int i; |
| 515 | |
| 516 | for(i = 0; i < size; i++) { |
| 517 | sprintf(hex, "%02x", *key); |
| 518 | hex += 2; |
| 519 | key++; |
| 520 | } |
| 521 | } |
| 522 | |
| 523 | /* |
| 524 | * Construct an encryption mapping: |
| 525 | * <cipher> <key> <iv_offset> <dev_path> <start> |
| 526 | */ |
| 527 | static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) |
| 528 | { |
| 529 | struct crypt_config *cc; |
| 530 | struct crypto_tfm *tfm; |
| 531 | char *tmp; |
| 532 | char *cipher; |
| 533 | char *chainmode; |
| 534 | char *ivmode; |
| 535 | char *ivopts; |
| 536 | unsigned int crypto_flags; |
| 537 | unsigned int key_size; |
| 538 | |
| 539 | if (argc != 5) { |
| 540 | ti->error = PFX "Not enough arguments"; |
| 541 | return -EINVAL; |
| 542 | } |
| 543 | |
| 544 | tmp = argv[0]; |
| 545 | cipher = strsep(&tmp, "-"); |
| 546 | chainmode = strsep(&tmp, "-"); |
| 547 | ivopts = strsep(&tmp, "-"); |
| 548 | ivmode = strsep(&ivopts, ":"); |
| 549 | |
| 550 | if (tmp) |
| 551 | DMWARN(PFX "Unexpected additional cipher options"); |
| 552 | |
| 553 | key_size = strlen(argv[1]) >> 1; |
| 554 | |
| 555 | cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL); |
| 556 | if (cc == NULL) { |
| 557 | ti->error = |
| 558 | PFX "Cannot allocate transparent encryption context"; |
| 559 | return -ENOMEM; |
| 560 | } |
| 561 | |
| 562 | cc->key_size = key_size; |
| 563 | if ((!key_size && strcmp(argv[1], "-") != 0) || |
| 564 | (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) { |
| 565 | ti->error = PFX "Error decoding key"; |
| 566 | goto bad1; |
| 567 | } |
| 568 | |
| 569 | /* Compatiblity mode for old dm-crypt cipher strings */ |
| 570 | if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) { |
| 571 | chainmode = "cbc"; |
| 572 | ivmode = "plain"; |
| 573 | } |
| 574 | |
| 575 | /* Choose crypto_flags according to chainmode */ |
| 576 | if (strcmp(chainmode, "cbc") == 0) |
| 577 | crypto_flags = CRYPTO_TFM_MODE_CBC; |
| 578 | else if (strcmp(chainmode, "ecb") == 0) |
| 579 | crypto_flags = CRYPTO_TFM_MODE_ECB; |
| 580 | else { |
| 581 | ti->error = PFX "Unknown chaining mode"; |
| 582 | goto bad1; |
| 583 | } |
| 584 | |
| 585 | if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) { |
| 586 | ti->error = PFX "This chaining mode requires an IV mechanism"; |
| 587 | goto bad1; |
| 588 | } |
| 589 | |
| 590 | tfm = crypto_alloc_tfm(cipher, crypto_flags); |
| 591 | if (!tfm) { |
| 592 | ti->error = PFX "Error allocating crypto tfm"; |
| 593 | goto bad1; |
| 594 | } |
| 595 | if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) { |
| 596 | ti->error = PFX "Expected cipher algorithm"; |
| 597 | goto bad2; |
| 598 | } |
| 599 | |
| 600 | cc->tfm = tfm; |
| 601 | |
| 602 | /* |
| 603 | * Choose ivmode. Valid modes: "plain", "essiv:<esshash>". |
| 604 | * See comments at iv code |
| 605 | */ |
| 606 | |
| 607 | if (ivmode == NULL) |
| 608 | cc->iv_gen_ops = NULL; |
| 609 | else if (strcmp(ivmode, "plain") == 0) |
| 610 | cc->iv_gen_ops = &crypt_iv_plain_ops; |
| 611 | else if (strcmp(ivmode, "essiv") == 0) |
| 612 | cc->iv_gen_ops = &crypt_iv_essiv_ops; |
| 613 | else { |
| 614 | ti->error = PFX "Invalid IV mode"; |
| 615 | goto bad2; |
| 616 | } |
| 617 | |
| 618 | if (cc->iv_gen_ops && cc->iv_gen_ops->ctr && |
| 619 | cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) |
| 620 | goto bad2; |
| 621 | |
| 622 | if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv) |
| 623 | /* at least a 64 bit sector number should fit in our buffer */ |
| 624 | cc->iv_size = max(crypto_tfm_alg_ivsize(tfm), |
| 625 | (unsigned int)(sizeof(u64) / sizeof(u8))); |
| 626 | else { |
| 627 | cc->iv_size = 0; |
| 628 | if (cc->iv_gen_ops) { |
| 629 | DMWARN(PFX "Selected cipher does not support IVs"); |
| 630 | if (cc->iv_gen_ops->dtr) |
| 631 | cc->iv_gen_ops->dtr(cc); |
| 632 | cc->iv_gen_ops = NULL; |
| 633 | } |
| 634 | } |
| 635 | |
| 636 | cc->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab, |
| 637 | mempool_free_slab, _crypt_io_pool); |
| 638 | if (!cc->io_pool) { |
| 639 | ti->error = PFX "Cannot allocate crypt io mempool"; |
| 640 | goto bad3; |
| 641 | } |
| 642 | |
| 643 | cc->page_pool = mempool_create(MIN_POOL_PAGES, mempool_alloc_page, |
| 644 | mempool_free_page, NULL); |
| 645 | if (!cc->page_pool) { |
| 646 | ti->error = PFX "Cannot allocate page mempool"; |
| 647 | goto bad4; |
| 648 | } |
| 649 | |
| 650 | if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) { |
| 651 | ti->error = PFX "Error setting key"; |
| 652 | goto bad5; |
| 653 | } |
| 654 | |
| 655 | if (sscanf(argv[2], SECTOR_FORMAT, &cc->iv_offset) != 1) { |
| 656 | ti->error = PFX "Invalid iv_offset sector"; |
| 657 | goto bad5; |
| 658 | } |
| 659 | |
| 660 | if (sscanf(argv[4], SECTOR_FORMAT, &cc->start) != 1) { |
| 661 | ti->error = PFX "Invalid device sector"; |
| 662 | goto bad5; |
| 663 | } |
| 664 | |
| 665 | if (dm_get_device(ti, argv[3], cc->start, ti->len, |
| 666 | dm_table_get_mode(ti->table), &cc->dev)) { |
| 667 | ti->error = PFX "Device lookup failed"; |
| 668 | goto bad5; |
| 669 | } |
| 670 | |
| 671 | if (ivmode && cc->iv_gen_ops) { |
| 672 | if (ivopts) |
| 673 | *(ivopts - 1) = ':'; |
| 674 | cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL); |
| 675 | if (!cc->iv_mode) { |
| 676 | ti->error = PFX "Error kmallocing iv_mode string"; |
| 677 | goto bad5; |
| 678 | } |
| 679 | strcpy(cc->iv_mode, ivmode); |
| 680 | } else |
| 681 | cc->iv_mode = NULL; |
| 682 | |
| 683 | ti->private = cc; |
| 684 | return 0; |
| 685 | |
| 686 | bad5: |
| 687 | mempool_destroy(cc->page_pool); |
| 688 | bad4: |
| 689 | mempool_destroy(cc->io_pool); |
| 690 | bad3: |
| 691 | if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) |
| 692 | cc->iv_gen_ops->dtr(cc); |
| 693 | bad2: |
| 694 | crypto_free_tfm(tfm); |
| 695 | bad1: |
| 696 | kfree(cc); |
| 697 | return -EINVAL; |
| 698 | } |
| 699 | |
| 700 | static void crypt_dtr(struct dm_target *ti) |
| 701 | { |
| 702 | struct crypt_config *cc = (struct crypt_config *) ti->private; |
| 703 | |
| 704 | mempool_destroy(cc->page_pool); |
| 705 | mempool_destroy(cc->io_pool); |
| 706 | |
| 707 | if (cc->iv_mode) |
| 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"); |