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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 | */ | |
dd0fc66f | 99 | static void *mempool_alloc_page(gfp_t gfp_mask, void *data) |
1da177e4 LT |
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 */ | |
eb6f1160 | 147 | hash_tfm = crypto_alloc_tfm(opts, CRYPTO_TFM_REQ_MAY_SLEEP); |
1da177e4 LT |
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), | |
eb6f1160 HX |
175 | CRYPTO_TFM_MODE_ECB | |
176 | CRYPTO_TFM_REQ_MAY_SLEEP); | |
1da177e4 LT |
177 | if (essiv_tfm == NULL) { |
178 | ti->error = PFX "Error allocating crypto tfm for ESSIV"; | |
179 | kfree(salt); | |
180 | return -EINVAL; | |
181 | } | |
182 | if (crypto_tfm_alg_blocksize(essiv_tfm) | |
183 | != crypto_tfm_alg_ivsize(cc->tfm)) { | |
184 | ti->error = PFX "Block size of ESSIV cipher does " | |
185 | "not match IV size of block cipher"; | |
186 | crypto_free_tfm(essiv_tfm); | |
187 | kfree(salt); | |
188 | return -EINVAL; | |
189 | } | |
190 | if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) { | |
191 | ti->error = PFX "Failed to set key for ESSIV cipher"; | |
192 | crypto_free_tfm(essiv_tfm); | |
193 | kfree(salt); | |
194 | return -EINVAL; | |
195 | } | |
196 | kfree(salt); | |
197 | ||
198 | cc->iv_gen_private = (void *)essiv_tfm; | |
199 | return 0; | |
200 | } | |
201 | ||
202 | static void crypt_iv_essiv_dtr(struct crypt_config *cc) | |
203 | { | |
204 | crypto_free_tfm((struct crypto_tfm *)cc->iv_gen_private); | |
205 | cc->iv_gen_private = NULL; | |
206 | } | |
207 | ||
208 | static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector) | |
209 | { | |
210 | struct scatterlist sg = { NULL, }; | |
211 | ||
212 | memset(iv, 0, cc->iv_size); | |
213 | *(u64 *)iv = cpu_to_le64(sector); | |
214 | ||
215 | sg.page = virt_to_page(iv); | |
216 | sg.offset = offset_in_page(iv); | |
217 | sg.length = cc->iv_size; | |
218 | crypto_cipher_encrypt((struct crypto_tfm *)cc->iv_gen_private, | |
219 | &sg, &sg, cc->iv_size); | |
220 | ||
221 | return 0; | |
222 | } | |
223 | ||
224 | static struct crypt_iv_operations crypt_iv_plain_ops = { | |
225 | .generator = crypt_iv_plain_gen | |
226 | }; | |
227 | ||
228 | static struct crypt_iv_operations crypt_iv_essiv_ops = { | |
229 | .ctr = crypt_iv_essiv_ctr, | |
230 | .dtr = crypt_iv_essiv_dtr, | |
231 | .generator = crypt_iv_essiv_gen | |
232 | }; | |
233 | ||
234 | ||
235 | static inline int | |
236 | crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out, | |
237 | struct scatterlist *in, unsigned int length, | |
238 | int write, sector_t sector) | |
239 | { | |
240 | u8 iv[cc->iv_size]; | |
241 | int r; | |
242 | ||
243 | if (cc->iv_gen_ops) { | |
244 | r = cc->iv_gen_ops->generator(cc, iv, sector); | |
245 | if (r < 0) | |
246 | return r; | |
247 | ||
248 | if (write) | |
249 | r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv); | |
250 | else | |
251 | r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv); | |
252 | } else { | |
253 | if (write) | |
254 | r = crypto_cipher_encrypt(cc->tfm, out, in, length); | |
255 | else | |
256 | r = crypto_cipher_decrypt(cc->tfm, out, in, length); | |
257 | } | |
258 | ||
259 | return r; | |
260 | } | |
261 | ||
262 | static void | |
263 | crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx, | |
264 | struct bio *bio_out, struct bio *bio_in, | |
265 | sector_t sector, int write) | |
266 | { | |
267 | ctx->bio_in = bio_in; | |
268 | ctx->bio_out = bio_out; | |
269 | ctx->offset_in = 0; | |
270 | ctx->offset_out = 0; | |
271 | ctx->idx_in = bio_in ? bio_in->bi_idx : 0; | |
272 | ctx->idx_out = bio_out ? bio_out->bi_idx : 0; | |
273 | ctx->sector = sector + cc->iv_offset; | |
274 | ctx->write = write; | |
275 | } | |
276 | ||
277 | /* | |
278 | * Encrypt / decrypt data from one bio to another one (can be the same one) | |
279 | */ | |
280 | static int crypt_convert(struct crypt_config *cc, | |
281 | struct convert_context *ctx) | |
282 | { | |
283 | int r = 0; | |
284 | ||
285 | while(ctx->idx_in < ctx->bio_in->bi_vcnt && | |
286 | ctx->idx_out < ctx->bio_out->bi_vcnt) { | |
287 | struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in); | |
288 | struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out); | |
289 | struct scatterlist sg_in = { | |
290 | .page = bv_in->bv_page, | |
291 | .offset = bv_in->bv_offset + ctx->offset_in, | |
292 | .length = 1 << SECTOR_SHIFT | |
293 | }; | |
294 | struct scatterlist sg_out = { | |
295 | .page = bv_out->bv_page, | |
296 | .offset = bv_out->bv_offset + ctx->offset_out, | |
297 | .length = 1 << SECTOR_SHIFT | |
298 | }; | |
299 | ||
300 | ctx->offset_in += sg_in.length; | |
301 | if (ctx->offset_in >= bv_in->bv_len) { | |
302 | ctx->offset_in = 0; | |
303 | ctx->idx_in++; | |
304 | } | |
305 | ||
306 | ctx->offset_out += sg_out.length; | |
307 | if (ctx->offset_out >= bv_out->bv_len) { | |
308 | ctx->offset_out = 0; | |
309 | ctx->idx_out++; | |
310 | } | |
311 | ||
312 | r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length, | |
313 | ctx->write, ctx->sector); | |
314 | if (r < 0) | |
315 | break; | |
316 | ||
317 | ctx->sector++; | |
318 | } | |
319 | ||
320 | return r; | |
321 | } | |
322 | ||
323 | /* | |
324 | * Generate a new unfragmented bio with the given size | |
325 | * This should never violate the device limitations | |
326 | * May return a smaller bio when running out of pages | |
327 | */ | |
328 | static struct bio * | |
329 | crypt_alloc_buffer(struct crypt_config *cc, unsigned int size, | |
330 | struct bio *base_bio, unsigned int *bio_vec_idx) | |
331 | { | |
332 | struct bio *bio; | |
333 | unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
334 | int gfp_mask = GFP_NOIO | __GFP_HIGHMEM; | |
1da177e4 LT |
335 | unsigned int i; |
336 | ||
337 | /* | |
bd53b714 NP |
338 | * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and |
339 | * to fail earlier. This is not necessary but increases throughput. | |
1da177e4 LT |
340 | * FIXME: Is this really intelligent? |
341 | */ | |
1da177e4 | 342 | if (base_bio) |
bd53b714 | 343 | bio = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC); |
1da177e4 | 344 | else |
bd53b714 NP |
345 | bio = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs); |
346 | if (!bio) | |
1da177e4 | 347 | return NULL; |
1da177e4 LT |
348 | |
349 | /* if the last bio was not complete, continue where that one ended */ | |
350 | bio->bi_idx = *bio_vec_idx; | |
351 | bio->bi_vcnt = *bio_vec_idx; | |
352 | bio->bi_size = 0; | |
353 | bio->bi_flags &= ~(1 << BIO_SEG_VALID); | |
354 | ||
355 | /* bio->bi_idx pages have already been allocated */ | |
356 | size -= bio->bi_idx * PAGE_SIZE; | |
357 | ||
358 | for(i = bio->bi_idx; i < nr_iovecs; i++) { | |
359 | struct bio_vec *bv = bio_iovec_idx(bio, i); | |
360 | ||
361 | bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask); | |
362 | if (!bv->bv_page) | |
363 | break; | |
364 | ||
365 | /* | |
366 | * if additional pages cannot be allocated without waiting, | |
367 | * return a partially allocated bio, the caller will then try | |
368 | * to allocate additional bios while submitting this partial bio | |
369 | */ | |
370 | if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1)) | |
371 | gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; | |
372 | ||
373 | bv->bv_offset = 0; | |
374 | if (size > PAGE_SIZE) | |
375 | bv->bv_len = PAGE_SIZE; | |
376 | else | |
377 | bv->bv_len = size; | |
378 | ||
379 | bio->bi_size += bv->bv_len; | |
380 | bio->bi_vcnt++; | |
381 | size -= bv->bv_len; | |
382 | } | |
383 | ||
1da177e4 LT |
384 | if (!bio->bi_size) { |
385 | bio_put(bio); | |
386 | return NULL; | |
387 | } | |
388 | ||
389 | /* | |
390 | * Remember the last bio_vec allocated to be able | |
391 | * to correctly continue after the splitting. | |
392 | */ | |
393 | *bio_vec_idx = bio->bi_vcnt; | |
394 | ||
395 | return bio; | |
396 | } | |
397 | ||
398 | static void crypt_free_buffer_pages(struct crypt_config *cc, | |
399 | struct bio *bio, unsigned int bytes) | |
400 | { | |
401 | unsigned int i, start, end; | |
402 | struct bio_vec *bv; | |
403 | ||
404 | /* | |
405 | * This is ugly, but Jens Axboe thinks that using bi_idx in the | |
406 | * endio function is too dangerous at the moment, so I calculate the | |
407 | * correct position using bi_vcnt and bi_size. | |
408 | * The bv_offset and bv_len fields might already be modified but we | |
409 | * know that we always allocated whole pages. | |
410 | * A fix to the bi_idx issue in the kernel is in the works, so | |
411 | * we will hopefully be able to revert to the cleaner solution soon. | |
412 | */ | |
413 | i = bio->bi_vcnt - 1; | |
414 | bv = bio_iovec_idx(bio, i); | |
415 | end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size; | |
416 | start = end - bytes; | |
417 | ||
418 | start >>= PAGE_SHIFT; | |
419 | if (!bio->bi_size) | |
420 | end = bio->bi_vcnt; | |
421 | else | |
422 | end >>= PAGE_SHIFT; | |
423 | ||
424 | for(i = start; i < end; i++) { | |
425 | bv = bio_iovec_idx(bio, i); | |
426 | BUG_ON(!bv->bv_page); | |
427 | mempool_free(bv->bv_page, cc->page_pool); | |
428 | bv->bv_page = NULL; | |
429 | } | |
430 | } | |
431 | ||
432 | /* | |
433 | * One of the bios was finished. Check for completion of | |
434 | * the whole request and correctly clean up the buffer. | |
435 | */ | |
436 | static void dec_pending(struct crypt_io *io, int error) | |
437 | { | |
438 | struct crypt_config *cc = (struct crypt_config *) io->target->private; | |
439 | ||
440 | if (error < 0) | |
441 | io->error = error; | |
442 | ||
443 | if (!atomic_dec_and_test(&io->pending)) | |
444 | return; | |
445 | ||
446 | if (io->first_clone) | |
447 | bio_put(io->first_clone); | |
448 | ||
449 | bio_endio(io->bio, io->bio->bi_size, io->error); | |
450 | ||
451 | mempool_free(io, cc->io_pool); | |
452 | } | |
453 | ||
454 | /* | |
455 | * kcryptd: | |
456 | * | |
457 | * Needed because it would be very unwise to do decryption in an | |
458 | * interrupt context, so bios returning from read requests get | |
459 | * queued here. | |
460 | */ | |
461 | static struct workqueue_struct *_kcryptd_workqueue; | |
462 | ||
463 | static void kcryptd_do_work(void *data) | |
464 | { | |
465 | struct crypt_io *io = (struct crypt_io *) data; | |
466 | struct crypt_config *cc = (struct crypt_config *) io->target->private; | |
467 | struct convert_context ctx; | |
468 | int r; | |
469 | ||
470 | crypt_convert_init(cc, &ctx, io->bio, io->bio, | |
471 | io->bio->bi_sector - io->target->begin, 0); | |
472 | r = crypt_convert(cc, &ctx); | |
473 | ||
474 | dec_pending(io, r); | |
475 | } | |
476 | ||
477 | static void kcryptd_queue_io(struct crypt_io *io) | |
478 | { | |
479 | INIT_WORK(&io->work, kcryptd_do_work, io); | |
480 | queue_work(_kcryptd_workqueue, &io->work); | |
481 | } | |
482 | ||
483 | /* | |
484 | * Decode key from its hex representation | |
485 | */ | |
486 | static int crypt_decode_key(u8 *key, char *hex, unsigned int size) | |
487 | { | |
488 | char buffer[3]; | |
489 | char *endp; | |
490 | unsigned int i; | |
491 | ||
492 | buffer[2] = '\0'; | |
493 | ||
494 | for(i = 0; i < size; i++) { | |
495 | buffer[0] = *hex++; | |
496 | buffer[1] = *hex++; | |
497 | ||
498 | key[i] = (u8)simple_strtoul(buffer, &endp, 16); | |
499 | ||
500 | if (endp != &buffer[2]) | |
501 | return -EINVAL; | |
502 | } | |
503 | ||
504 | if (*hex != '\0') | |
505 | return -EINVAL; | |
506 | ||
507 | return 0; | |
508 | } | |
509 | ||
510 | /* | |
511 | * Encode key into its hex representation | |
512 | */ | |
513 | static void crypt_encode_key(char *hex, u8 *key, unsigned int size) | |
514 | { | |
515 | unsigned int i; | |
516 | ||
517 | for(i = 0; i < size; i++) { | |
518 | sprintf(hex, "%02x", *key); | |
519 | hex += 2; | |
520 | key++; | |
521 | } | |
522 | } | |
523 | ||
524 | /* | |
525 | * Construct an encryption mapping: | |
526 | * <cipher> <key> <iv_offset> <dev_path> <start> | |
527 | */ | |
528 | static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) | |
529 | { | |
530 | struct crypt_config *cc; | |
531 | struct crypto_tfm *tfm; | |
532 | char *tmp; | |
533 | char *cipher; | |
534 | char *chainmode; | |
535 | char *ivmode; | |
536 | char *ivopts; | |
537 | unsigned int crypto_flags; | |
538 | unsigned int key_size; | |
539 | ||
540 | if (argc != 5) { | |
541 | ti->error = PFX "Not enough arguments"; | |
542 | return -EINVAL; | |
543 | } | |
544 | ||
545 | tmp = argv[0]; | |
546 | cipher = strsep(&tmp, "-"); | |
547 | chainmode = strsep(&tmp, "-"); | |
548 | ivopts = strsep(&tmp, "-"); | |
549 | ivmode = strsep(&ivopts, ":"); | |
550 | ||
551 | if (tmp) | |
552 | DMWARN(PFX "Unexpected additional cipher options"); | |
553 | ||
554 | key_size = strlen(argv[1]) >> 1; | |
555 | ||
556 | cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL); | |
557 | if (cc == NULL) { | |
558 | ti->error = | |
559 | PFX "Cannot allocate transparent encryption context"; | |
560 | return -ENOMEM; | |
561 | } | |
562 | ||
563 | cc->key_size = key_size; | |
564 | if ((!key_size && strcmp(argv[1], "-") != 0) || | |
565 | (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) { | |
566 | ti->error = PFX "Error decoding key"; | |
567 | goto bad1; | |
568 | } | |
569 | ||
570 | /* Compatiblity mode for old dm-crypt cipher strings */ | |
571 | if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) { | |
572 | chainmode = "cbc"; | |
573 | ivmode = "plain"; | |
574 | } | |
575 | ||
576 | /* Choose crypto_flags according to chainmode */ | |
577 | if (strcmp(chainmode, "cbc") == 0) | |
578 | crypto_flags = CRYPTO_TFM_MODE_CBC; | |
579 | else if (strcmp(chainmode, "ecb") == 0) | |
580 | crypto_flags = CRYPTO_TFM_MODE_ECB; | |
581 | else { | |
582 | ti->error = PFX "Unknown chaining mode"; | |
583 | goto bad1; | |
584 | } | |
585 | ||
586 | if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) { | |
587 | ti->error = PFX "This chaining mode requires an IV mechanism"; | |
588 | goto bad1; | |
589 | } | |
590 | ||
eb6f1160 | 591 | tfm = crypto_alloc_tfm(cipher, crypto_flags | CRYPTO_TFM_REQ_MAY_SLEEP); |
1da177e4 LT |
592 | if (!tfm) { |
593 | ti->error = PFX "Error allocating crypto tfm"; | |
594 | goto bad1; | |
595 | } | |
596 | if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) { | |
597 | ti->error = PFX "Expected cipher algorithm"; | |
598 | goto bad2; | |
599 | } | |
600 | ||
601 | cc->tfm = tfm; | |
602 | ||
603 | /* | |
604 | * Choose ivmode. Valid modes: "plain", "essiv:<esshash>". | |
605 | * See comments at iv code | |
606 | */ | |
607 | ||
608 | if (ivmode == NULL) | |
609 | cc->iv_gen_ops = NULL; | |
610 | else if (strcmp(ivmode, "plain") == 0) | |
611 | cc->iv_gen_ops = &crypt_iv_plain_ops; | |
612 | else if (strcmp(ivmode, "essiv") == 0) | |
613 | cc->iv_gen_ops = &crypt_iv_essiv_ops; | |
614 | else { | |
615 | ti->error = PFX "Invalid IV mode"; | |
616 | goto bad2; | |
617 | } | |
618 | ||
619 | if (cc->iv_gen_ops && cc->iv_gen_ops->ctr && | |
620 | cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0) | |
621 | goto bad2; | |
622 | ||
623 | if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv) | |
624 | /* at least a 64 bit sector number should fit in our buffer */ | |
625 | cc->iv_size = max(crypto_tfm_alg_ivsize(tfm), | |
626 | (unsigned int)(sizeof(u64) / sizeof(u8))); | |
627 | else { | |
628 | cc->iv_size = 0; | |
629 | if (cc->iv_gen_ops) { | |
630 | DMWARN(PFX "Selected cipher does not support IVs"); | |
631 | if (cc->iv_gen_ops->dtr) | |
632 | cc->iv_gen_ops->dtr(cc); | |
633 | cc->iv_gen_ops = NULL; | |
634 | } | |
635 | } | |
636 | ||
637 | cc->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab, | |
638 | mempool_free_slab, _crypt_io_pool); | |
639 | if (!cc->io_pool) { | |
640 | ti->error = PFX "Cannot allocate crypt io mempool"; | |
641 | goto bad3; | |
642 | } | |
643 | ||
644 | cc->page_pool = mempool_create(MIN_POOL_PAGES, mempool_alloc_page, | |
645 | mempool_free_page, NULL); | |
646 | if (!cc->page_pool) { | |
647 | ti->error = PFX "Cannot allocate page mempool"; | |
648 | goto bad4; | |
649 | } | |
650 | ||
651 | if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) { | |
652 | ti->error = PFX "Error setting key"; | |
653 | goto bad5; | |
654 | } | |
655 | ||
656 | if (sscanf(argv[2], SECTOR_FORMAT, &cc->iv_offset) != 1) { | |
657 | ti->error = PFX "Invalid iv_offset sector"; | |
658 | goto bad5; | |
659 | } | |
660 | ||
661 | if (sscanf(argv[4], SECTOR_FORMAT, &cc->start) != 1) { | |
662 | ti->error = PFX "Invalid device sector"; | |
663 | goto bad5; | |
664 | } | |
665 | ||
666 | if (dm_get_device(ti, argv[3], cc->start, ti->len, | |
667 | dm_table_get_mode(ti->table), &cc->dev)) { | |
668 | ti->error = PFX "Device lookup failed"; | |
669 | goto bad5; | |
670 | } | |
671 | ||
672 | if (ivmode && cc->iv_gen_ops) { | |
673 | if (ivopts) | |
674 | *(ivopts - 1) = ':'; | |
675 | cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL); | |
676 | if (!cc->iv_mode) { | |
677 | ti->error = PFX "Error kmallocing iv_mode string"; | |
678 | goto bad5; | |
679 | } | |
680 | strcpy(cc->iv_mode, ivmode); | |
681 | } else | |
682 | cc->iv_mode = NULL; | |
683 | ||
684 | ti->private = cc; | |
685 | return 0; | |
686 | ||
687 | bad5: | |
688 | mempool_destroy(cc->page_pool); | |
689 | bad4: | |
690 | mempool_destroy(cc->io_pool); | |
691 | bad3: | |
692 | if (cc->iv_gen_ops && cc->iv_gen_ops->dtr) | |
693 | cc->iv_gen_ops->dtr(cc); | |
694 | bad2: | |
695 | crypto_free_tfm(tfm); | |
696 | bad1: | |
697 | kfree(cc); | |
698 | return -EINVAL; | |
699 | } | |
700 | ||
701 | static void crypt_dtr(struct dm_target *ti) | |
702 | { | |
703 | struct crypt_config *cc = (struct crypt_config *) ti->private; | |
704 | ||
705 | mempool_destroy(cc->page_pool); | |
706 | mempool_destroy(cc->io_pool); | |
707 | ||
990a8baf | 708 | kfree(cc->iv_mode); |
1da177e4 LT |
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"); |