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1da177e4 LT |
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; | |
1da177e4 LT |
334 | unsigned int i; |
335 | ||
336 | /* | |
bd53b714 NP |
337 | * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and |
338 | * to fail earlier. This is not necessary but increases throughput. | |
1da177e4 LT |
339 | * FIXME: Is this really intelligent? |
340 | */ | |
1da177e4 | 341 | if (base_bio) |
bd53b714 | 342 | bio = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC); |
1da177e4 | 343 | else |
bd53b714 NP |
344 | bio = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs); |
345 | if (!bio) | |
1da177e4 | 346 | return NULL; |
1da177e4 LT |
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 | ||
1da177e4 LT |
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 | ||
990a8baf | 707 | kfree(cc->iv_mode); |
1da177e4 LT |
708 | if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) |
709 | cc->iv_gen_ops->dtr(cc); | |
710 | crypto_free_tfm(cc->tfm); | |
711 | dm_put_device(ti, cc->dev); | |
712 | kfree(cc); | |
713 | } | |
714 | ||
715 | static int crypt_endio(struct bio *bio, unsigned int done, int error) | |
716 | { | |
717 | struct crypt_io *io = (struct crypt_io *) bio->bi_private; | |
718 | struct crypt_config *cc = (struct crypt_config *) io->target->private; | |
719 | ||
720 | if (bio_data_dir(bio) == WRITE) { | |
721 | /* | |
722 | * free the processed pages, even if | |
723 | * it's only a partially completed write | |
724 | */ | |
725 | crypt_free_buffer_pages(cc, bio, done); | |
726 | } | |
727 | ||
728 | if (bio->bi_size) | |
729 | return 1; | |
730 | ||
731 | bio_put(bio); | |
732 | ||
733 | /* | |
734 | * successful reads are decrypted by the worker thread | |
735 | */ | |
736 | if ((bio_data_dir(bio) == READ) | |
737 | && bio_flagged(bio, BIO_UPTODATE)) { | |
738 | kcryptd_queue_io(io); | |
739 | return 0; | |
740 | } | |
741 | ||
742 | dec_pending(io, error); | |
743 | return error; | |
744 | } | |
745 | ||
746 | static inline struct bio * | |
747 | crypt_clone(struct crypt_config *cc, struct crypt_io *io, struct bio *bio, | |
748 | sector_t sector, unsigned int *bvec_idx, | |
749 | struct convert_context *ctx) | |
750 | { | |
751 | struct bio *clone; | |
752 | ||
753 | if (bio_data_dir(bio) == WRITE) { | |
754 | clone = crypt_alloc_buffer(cc, bio->bi_size, | |
755 | io->first_clone, bvec_idx); | |
756 | if (clone) { | |
757 | ctx->bio_out = clone; | |
758 | if (crypt_convert(cc, ctx) < 0) { | |
759 | crypt_free_buffer_pages(cc, clone, | |
760 | clone->bi_size); | |
761 | bio_put(clone); | |
762 | return NULL; | |
763 | } | |
764 | } | |
765 | } else { | |
766 | /* | |
767 | * The block layer might modify the bvec array, so always | |
768 | * copy the required bvecs because we need the original | |
769 | * one in order to decrypt the whole bio data *afterwards*. | |
770 | */ | |
771 | clone = bio_alloc(GFP_NOIO, bio_segments(bio)); | |
772 | if (clone) { | |
773 | clone->bi_idx = 0; | |
774 | clone->bi_vcnt = bio_segments(bio); | |
775 | clone->bi_size = bio->bi_size; | |
776 | memcpy(clone->bi_io_vec, bio_iovec(bio), | |
777 | sizeof(struct bio_vec) * clone->bi_vcnt); | |
778 | } | |
779 | } | |
780 | ||
781 | if (!clone) | |
782 | return NULL; | |
783 | ||
784 | clone->bi_private = io; | |
785 | clone->bi_end_io = crypt_endio; | |
786 | clone->bi_bdev = cc->dev->bdev; | |
787 | clone->bi_sector = cc->start + sector; | |
788 | clone->bi_rw = bio->bi_rw; | |
789 | ||
790 | return clone; | |
791 | } | |
792 | ||
793 | static int crypt_map(struct dm_target *ti, struct bio *bio, | |
794 | union map_info *map_context) | |
795 | { | |
796 | struct crypt_config *cc = (struct crypt_config *) ti->private; | |
797 | struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO); | |
798 | struct convert_context ctx; | |
799 | struct bio *clone; | |
800 | unsigned int remaining = bio->bi_size; | |
801 | sector_t sector = bio->bi_sector - ti->begin; | |
802 | unsigned int bvec_idx = 0; | |
803 | ||
804 | io->target = ti; | |
805 | io->bio = bio; | |
806 | io->first_clone = NULL; | |
807 | io->error = 0; | |
808 | atomic_set(&io->pending, 1); /* hold a reference */ | |
809 | ||
810 | if (bio_data_dir(bio) == WRITE) | |
811 | crypt_convert_init(cc, &ctx, NULL, bio, sector, 1); | |
812 | ||
813 | /* | |
814 | * The allocated buffers can be smaller than the whole bio, | |
815 | * so repeat the whole process until all the data can be handled. | |
816 | */ | |
817 | while (remaining) { | |
818 | clone = crypt_clone(cc, io, bio, sector, &bvec_idx, &ctx); | |
819 | if (!clone) | |
820 | goto cleanup; | |
821 | ||
822 | if (!io->first_clone) { | |
823 | /* | |
824 | * hold a reference to the first clone, because it | |
825 | * holds the bio_vec array and that can't be freed | |
826 | * before all other clones are released | |
827 | */ | |
828 | bio_get(clone); | |
829 | io->first_clone = clone; | |
830 | } | |
831 | atomic_inc(&io->pending); | |
832 | ||
833 | remaining -= clone->bi_size; | |
834 | sector += bio_sectors(clone); | |
835 | ||
836 | generic_make_request(clone); | |
837 | ||
838 | /* out of memory -> run queues */ | |
839 | if (remaining) | |
840 | blk_congestion_wait(bio_data_dir(clone), HZ/100); | |
841 | } | |
842 | ||
843 | /* drop reference, clones could have returned before we reach this */ | |
844 | dec_pending(io, 0); | |
845 | return 0; | |
846 | ||
847 | cleanup: | |
848 | if (io->first_clone) { | |
849 | dec_pending(io, -ENOMEM); | |
850 | return 0; | |
851 | } | |
852 | ||
853 | /* if no bio has been dispatched yet, we can directly return the error */ | |
854 | mempool_free(io, cc->io_pool); | |
855 | return -ENOMEM; | |
856 | } | |
857 | ||
858 | static int crypt_status(struct dm_target *ti, status_type_t type, | |
859 | char *result, unsigned int maxlen) | |
860 | { | |
861 | struct crypt_config *cc = (struct crypt_config *) ti->private; | |
862 | const char *cipher; | |
863 | const char *chainmode = NULL; | |
864 | unsigned int sz = 0; | |
865 | ||
866 | switch (type) { | |
867 | case STATUSTYPE_INFO: | |
868 | result[0] = '\0'; | |
869 | break; | |
870 | ||
871 | case STATUSTYPE_TABLE: | |
872 | cipher = crypto_tfm_alg_name(cc->tfm); | |
873 | ||
874 | switch(cc->tfm->crt_cipher.cit_mode) { | |
875 | case CRYPTO_TFM_MODE_CBC: | |
876 | chainmode = "cbc"; | |
877 | break; | |
878 | case CRYPTO_TFM_MODE_ECB: | |
879 | chainmode = "ecb"; | |
880 | break; | |
881 | default: | |
882 | BUG(); | |
883 | } | |
884 | ||
885 | if (cc->iv_mode) | |
886 | DMEMIT("%s-%s-%s ", cipher, chainmode, cc->iv_mode); | |
887 | else | |
888 | DMEMIT("%s-%s ", cipher, chainmode); | |
889 | ||
890 | if (cc->key_size > 0) { | |
891 | if ((maxlen - sz) < ((cc->key_size << 1) + 1)) | |
892 | return -ENOMEM; | |
893 | ||
894 | crypt_encode_key(result + sz, cc->key, cc->key_size); | |
895 | sz += cc->key_size << 1; | |
896 | } else { | |
897 | if (sz >= maxlen) | |
898 | return -ENOMEM; | |
899 | result[sz++] = '-'; | |
900 | } | |
901 | ||
902 | DMEMIT(" " SECTOR_FORMAT " %s " SECTOR_FORMAT, | |
903 | cc->iv_offset, cc->dev->name, cc->start); | |
904 | break; | |
905 | } | |
906 | return 0; | |
907 | } | |
908 | ||
909 | static struct target_type crypt_target = { | |
910 | .name = "crypt", | |
911 | .version= {1, 1, 0}, | |
912 | .module = THIS_MODULE, | |
913 | .ctr = crypt_ctr, | |
914 | .dtr = crypt_dtr, | |
915 | .map = crypt_map, | |
916 | .status = crypt_status, | |
917 | }; | |
918 | ||
919 | static int __init dm_crypt_init(void) | |
920 | { | |
921 | int r; | |
922 | ||
923 | _crypt_io_pool = kmem_cache_create("dm-crypt_io", | |
924 | sizeof(struct crypt_io), | |
925 | 0, 0, NULL, NULL); | |
926 | if (!_crypt_io_pool) | |
927 | return -ENOMEM; | |
928 | ||
929 | _kcryptd_workqueue = create_workqueue("kcryptd"); | |
930 | if (!_kcryptd_workqueue) { | |
931 | r = -ENOMEM; | |
932 | DMERR(PFX "couldn't create kcryptd"); | |
933 | goto bad1; | |
934 | } | |
935 | ||
936 | r = dm_register_target(&crypt_target); | |
937 | if (r < 0) { | |
938 | DMERR(PFX "register failed %d", r); | |
939 | goto bad2; | |
940 | } | |
941 | ||
942 | return 0; | |
943 | ||
944 | bad2: | |
945 | destroy_workqueue(_kcryptd_workqueue); | |
946 | bad1: | |
947 | kmem_cache_destroy(_crypt_io_pool); | |
948 | return r; | |
949 | } | |
950 | ||
951 | static void __exit dm_crypt_exit(void) | |
952 | { | |
953 | int r = dm_unregister_target(&crypt_target); | |
954 | ||
955 | if (r < 0) | |
956 | DMERR(PFX "unregister failed %d", r); | |
957 | ||
958 | destroy_workqueue(_kcryptd_workqueue); | |
959 | kmem_cache_destroy(_crypt_io_pool); | |
960 | } | |
961 | ||
962 | module_init(dm_crypt_init); | |
963 | module_exit(dm_crypt_exit); | |
964 | ||
965 | MODULE_AUTHOR("Christophe Saout <christophe@saout.de>"); | |
966 | MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption"); | |
967 | MODULE_LICENSE("GPL"); |