1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright 2019 Google LLC
4 */
5
6 /*
7 * Refer to Documentation/block/inline-encryption.rst for detailed explanation.
8 */
9
10 #define pr_fmt(fmt) "blk-crypto-fallback: " fmt
11
12 #include <crypto/skcipher.h>
13 #include <linux/blk-crypto.h>
14 #include <linux/blk-crypto-profile.h>
15 #include <linux/blkdev.h>
16 #include <linux/crypto.h>
17 #include <linux/mempool.h>
18 #include <linux/module.h>
19 #include <linux/random.h>
20 #include <linux/scatterlist.h>
21
22 #include "blk-cgroup.h"
23 #include "blk-crypto-internal.h"
24
25 static unsigned int num_prealloc_bounce_pg = 32;
26 module_param(num_prealloc_bounce_pg, uint, 0);
27 MODULE_PARM_DESC(num_prealloc_bounce_pg,
28 "Number of preallocated bounce pages for the blk-crypto crypto API fallback");
29
30 static unsigned int blk_crypto_num_keyslots = 100;
31 module_param_named(num_keyslots, blk_crypto_num_keyslots, uint, 0);
32 MODULE_PARM_DESC(num_keyslots,
33 "Number of keyslots for the blk-crypto crypto API fallback");
34
35 static unsigned int num_prealloc_fallback_crypt_ctxs = 128;
36 module_param(num_prealloc_fallback_crypt_ctxs, uint, 0);
37 MODULE_PARM_DESC(num_prealloc_crypt_fallback_ctxs,
38 "Number of preallocated bio fallback crypto contexts for blk-crypto to use during crypto API fallback");
39
40 struct bio_fallback_crypt_ctx {
41 struct bio_crypt_ctx crypt_ctx;
42 /*
43 * Copy of the bvec_iter when this bio was submitted.
44 * We only want to en/decrypt the part of the bio as described by the
45 * bvec_iter upon submission because bio might be split before being
46 * resubmitted
47 */
48 struct bvec_iter crypt_iter;
49 union {
50 struct {
51 struct work_struct work;
52 struct bio *bio;
53 };
54 struct {
55 void *bi_private_orig;
56 bio_end_io_t *bi_end_io_orig;
57 };
58 };
59 };
60
61 static struct kmem_cache *bio_fallback_crypt_ctx_cache;
62 static mempool_t *bio_fallback_crypt_ctx_pool;
63
64 /*
65 * Allocating a crypto tfm during I/O can deadlock, so we have to preallocate
66 * all of a mode's tfms when that mode starts being used. Since each mode may
67 * need all the keyslots at some point, each mode needs its own tfm for each
68 * keyslot; thus, a keyslot may contain tfms for multiple modes. However, to
69 * match the behavior of real inline encryption hardware (which only supports a
70 * single encryption context per keyslot), we only allow one tfm per keyslot to
71 * be used at a time - the rest of the unused tfms have their keys cleared.
72 */
73 static DEFINE_MUTEX(tfms_init_lock);
74 static bool tfms_inited[BLK_ENCRYPTION_MODE_MAX];
75
76 static struct blk_crypto_fallback_keyslot {
77 enum blk_crypto_mode_num crypto_mode;
78 struct crypto_skcipher *tfms[BLK_ENCRYPTION_MODE_MAX];
79 } *blk_crypto_keyslots;
80
81 static struct blk_crypto_profile *blk_crypto_fallback_profile;
82 static struct workqueue_struct *blk_crypto_wq;
83 static mempool_t *blk_crypto_bounce_page_pool;
84 static struct bio_set crypto_bio_split;
85
86 /*
87 * This is the key we set when evicting a keyslot. This *should* be the all 0's
88 * key, but AES-XTS rejects that key, so we use some random bytes instead.
89 */
90 static u8 blank_key[BLK_CRYPTO_MAX_STANDARD_KEY_SIZE];
91
blk_crypto_fallback_evict_keyslot(unsigned int slot)92 static void blk_crypto_fallback_evict_keyslot(unsigned int slot)
93 {
94 struct blk_crypto_fallback_keyslot *slotp = &blk_crypto_keyslots[slot];
95 enum blk_crypto_mode_num crypto_mode = slotp->crypto_mode;
96 int err;
97
98 WARN_ON(slotp->crypto_mode == BLK_ENCRYPTION_MODE_INVALID);
99
100 /* Clear the key in the skcipher */
101 err = crypto_skcipher_setkey(slotp->tfms[crypto_mode], blank_key,
102 blk_crypto_modes[crypto_mode].keysize);
103 WARN_ON(err);
104 slotp->crypto_mode = BLK_ENCRYPTION_MODE_INVALID;
105 }
106
107 static int
blk_crypto_fallback_keyslot_program(struct blk_crypto_profile * profile,const struct blk_crypto_key * key,unsigned int slot)108 blk_crypto_fallback_keyslot_program(struct blk_crypto_profile *profile,
109 const struct blk_crypto_key *key,
110 unsigned int slot)
111 {
112 struct blk_crypto_fallback_keyslot *slotp = &blk_crypto_keyslots[slot];
113 const enum blk_crypto_mode_num crypto_mode =
114 key->crypto_cfg.crypto_mode;
115 int err;
116
117 if (crypto_mode != slotp->crypto_mode &&
118 slotp->crypto_mode != BLK_ENCRYPTION_MODE_INVALID)
119 blk_crypto_fallback_evict_keyslot(slot);
120
121 slotp->crypto_mode = crypto_mode;
122 err = crypto_skcipher_setkey(slotp->tfms[crypto_mode], key->raw,
123 key->size);
124 if (err) {
125 blk_crypto_fallback_evict_keyslot(slot);
126 return err;
127 }
128 return 0;
129 }
130
blk_crypto_fallback_keyslot_evict(struct blk_crypto_profile * profile,const struct blk_crypto_key * key,unsigned int slot)131 static int blk_crypto_fallback_keyslot_evict(struct blk_crypto_profile *profile,
132 const struct blk_crypto_key *key,
133 unsigned int slot)
134 {
135 blk_crypto_fallback_evict_keyslot(slot);
136 return 0;
137 }
138
139 static const struct blk_crypto_ll_ops blk_crypto_fallback_ll_ops = {
140 .keyslot_program = blk_crypto_fallback_keyslot_program,
141 .keyslot_evict = blk_crypto_fallback_keyslot_evict,
142 };
143
blk_crypto_fallback_encrypt_endio(struct bio * enc_bio)144 static void blk_crypto_fallback_encrypt_endio(struct bio *enc_bio)
145 {
146 struct bio *src_bio = enc_bio->bi_private;
147 int i;
148
149 for (i = 0; i < enc_bio->bi_vcnt; i++)
150 mempool_free(enc_bio->bi_io_vec[i].bv_page,
151 blk_crypto_bounce_page_pool);
152
153 src_bio->bi_status = enc_bio->bi_status;
154
155 bio_uninit(enc_bio);
156 kfree(enc_bio);
157 bio_endio(src_bio);
158 }
159
blk_crypto_fallback_clone_bio(struct bio * bio_src)160 static struct bio *blk_crypto_fallback_clone_bio(struct bio *bio_src)
161 {
162 unsigned int nr_segs = bio_segments(bio_src);
163 struct bvec_iter iter;
164 struct bio_vec bv;
165 struct bio *bio;
166
167 bio = bio_kmalloc(nr_segs, GFP_NOIO);
168 if (!bio)
169 return NULL;
170 bio_init(bio, bio_src->bi_bdev, bio->bi_inline_vecs, nr_segs,
171 bio_src->bi_opf);
172 if (bio_flagged(bio_src, BIO_REMAPPED))
173 bio_set_flag(bio, BIO_REMAPPED);
174 bio->bi_ioprio = bio_src->bi_ioprio;
175 bio->bi_write_hint = bio_src->bi_write_hint;
176 bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
177 bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
178
179 bio_for_each_segment(bv, bio_src, iter)
180 bio->bi_io_vec[bio->bi_vcnt++] = bv;
181
182 bio_clone_blkg_association(bio, bio_src);
183
184 bio_clone_skip_dm_default_key(bio, bio_src);
185
186 return bio;
187 }
188
189 static bool
blk_crypto_fallback_alloc_cipher_req(struct blk_crypto_keyslot * slot,struct skcipher_request ** ciph_req_ret,struct crypto_wait * wait)190 blk_crypto_fallback_alloc_cipher_req(struct blk_crypto_keyslot *slot,
191 struct skcipher_request **ciph_req_ret,
192 struct crypto_wait *wait)
193 {
194 struct skcipher_request *ciph_req;
195 const struct blk_crypto_fallback_keyslot *slotp;
196 int keyslot_idx = blk_crypto_keyslot_index(slot);
197
198 slotp = &blk_crypto_keyslots[keyslot_idx];
199 ciph_req = skcipher_request_alloc(slotp->tfms[slotp->crypto_mode],
200 GFP_NOIO);
201 if (!ciph_req)
202 return false;
203
204 skcipher_request_set_callback(ciph_req,
205 CRYPTO_TFM_REQ_MAY_BACKLOG |
206 CRYPTO_TFM_REQ_MAY_SLEEP,
207 crypto_req_done, wait);
208 *ciph_req_ret = ciph_req;
209
210 return true;
211 }
212
blk_crypto_fallback_split_bio_if_needed(struct bio ** bio_ptr)213 static bool blk_crypto_fallback_split_bio_if_needed(struct bio **bio_ptr)
214 {
215 struct bio *bio = *bio_ptr;
216 unsigned int i = 0;
217 unsigned int num_sectors = 0;
218 struct bio_vec bv;
219 struct bvec_iter iter;
220
221 bio_for_each_segment(bv, bio, iter) {
222 num_sectors += bv.bv_len >> SECTOR_SHIFT;
223 if (++i == BIO_MAX_VECS)
224 break;
225 }
226 if (num_sectors < bio_sectors(bio)) {
227 struct bio *split_bio;
228
229 split_bio = bio_split(bio, num_sectors, GFP_NOIO,
230 &crypto_bio_split);
231 if (!split_bio) {
232 bio->bi_status = BLK_STS_RESOURCE;
233 return false;
234 }
235 bio_chain(split_bio, bio);
236 submit_bio_noacct(bio);
237 *bio_ptr = split_bio;
238 }
239
240 return true;
241 }
242
243 union blk_crypto_iv {
244 __le64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
245 u8 bytes[BLK_CRYPTO_MAX_IV_SIZE];
246 };
247
blk_crypto_dun_to_iv(const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],union blk_crypto_iv * iv)248 static void blk_crypto_dun_to_iv(const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
249 union blk_crypto_iv *iv)
250 {
251 int i;
252
253 for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++)
254 iv->dun[i] = cpu_to_le64(dun[i]);
255 }
256
257 /*
258 * The crypto API fallback's encryption routine.
259 * Allocate a bounce bio for encryption, encrypt the input bio using crypto API,
260 * and replace *bio_ptr with the bounce bio. May split input bio if it's too
261 * large. Returns true on success. Returns false and sets bio->bi_status on
262 * error.
263 */
blk_crypto_fallback_encrypt_bio(struct bio ** bio_ptr)264 static bool blk_crypto_fallback_encrypt_bio(struct bio **bio_ptr)
265 {
266 struct bio *src_bio, *enc_bio;
267 struct bio_crypt_ctx *bc;
268 struct blk_crypto_keyslot *slot;
269 int data_unit_size;
270 struct skcipher_request *ciph_req = NULL;
271 DECLARE_CRYPTO_WAIT(wait);
272 u64 curr_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
273 struct scatterlist src, dst;
274 union blk_crypto_iv iv;
275 unsigned int i, j;
276 bool ret = false;
277 blk_status_t blk_st;
278
279 /* Split the bio if it's too big for single page bvec */
280 if (!blk_crypto_fallback_split_bio_if_needed(bio_ptr))
281 return false;
282
283 src_bio = *bio_ptr;
284 bc = src_bio->bi_crypt_context;
285 data_unit_size = bc->bc_key->crypto_cfg.data_unit_size;
286
287 /* Allocate bounce bio for encryption */
288 enc_bio = blk_crypto_fallback_clone_bio(src_bio);
289 if (!enc_bio) {
290 src_bio->bi_status = BLK_STS_RESOURCE;
291 return false;
292 }
293
294 /*
295 * Get a blk-crypto-fallback keyslot that contains a crypto_skcipher for
296 * this bio's algorithm and key.
297 */
298 blk_st = blk_crypto_get_keyslot(blk_crypto_fallback_profile,
299 bc->bc_key, &slot);
300 if (blk_st != BLK_STS_OK) {
301 src_bio->bi_status = blk_st;
302 goto out_put_enc_bio;
303 }
304
305 /* and then allocate an skcipher_request for it */
306 if (!blk_crypto_fallback_alloc_cipher_req(slot, &ciph_req, &wait)) {
307 src_bio->bi_status = BLK_STS_RESOURCE;
308 goto out_release_keyslot;
309 }
310
311 memcpy(curr_dun, bc->bc_dun, sizeof(curr_dun));
312 sg_init_table(&src, 1);
313 sg_init_table(&dst, 1);
314
315 skcipher_request_set_crypt(ciph_req, &src, &dst, data_unit_size,
316 iv.bytes);
317
318 /* Encrypt each page in the bounce bio */
319 for (i = 0; i < enc_bio->bi_vcnt; i++) {
320 struct bio_vec *enc_bvec = &enc_bio->bi_io_vec[i];
321 struct page *plaintext_page = enc_bvec->bv_page;
322 struct page *ciphertext_page =
323 mempool_alloc(blk_crypto_bounce_page_pool, GFP_NOIO);
324
325 enc_bvec->bv_page = ciphertext_page;
326
327 if (!ciphertext_page) {
328 src_bio->bi_status = BLK_STS_RESOURCE;
329 goto out_free_bounce_pages;
330 }
331
332 sg_set_page(&src, plaintext_page, data_unit_size,
333 enc_bvec->bv_offset);
334 sg_set_page(&dst, ciphertext_page, data_unit_size,
335 enc_bvec->bv_offset);
336
337 /* Encrypt each data unit in this page */
338 for (j = 0; j < enc_bvec->bv_len; j += data_unit_size) {
339 blk_crypto_dun_to_iv(curr_dun, &iv);
340 if (crypto_wait_req(crypto_skcipher_encrypt(ciph_req),
341 &wait)) {
342 i++;
343 src_bio->bi_status = BLK_STS_IOERR;
344 goto out_free_bounce_pages;
345 }
346 bio_crypt_dun_increment(curr_dun, 1);
347 src.offset += data_unit_size;
348 dst.offset += data_unit_size;
349 }
350 }
351
352 enc_bio->bi_private = src_bio;
353 enc_bio->bi_end_io = blk_crypto_fallback_encrypt_endio;
354 *bio_ptr = enc_bio;
355 ret = true;
356
357 enc_bio = NULL;
358 goto out_free_ciph_req;
359
360 out_free_bounce_pages:
361 while (i > 0)
362 mempool_free(enc_bio->bi_io_vec[--i].bv_page,
363 blk_crypto_bounce_page_pool);
364 out_free_ciph_req:
365 skcipher_request_free(ciph_req);
366 out_release_keyslot:
367 blk_crypto_put_keyslot(slot);
368 out_put_enc_bio:
369 if (enc_bio)
370 bio_uninit(enc_bio);
371 kfree(enc_bio);
372 return ret;
373 }
374
375 /*
376 * The crypto API fallback's main decryption routine.
377 * Decrypts input bio in place, and calls bio_endio on the bio.
378 */
blk_crypto_fallback_decrypt_bio(struct work_struct * work)379 static void blk_crypto_fallback_decrypt_bio(struct work_struct *work)
380 {
381 struct bio_fallback_crypt_ctx *f_ctx =
382 container_of(work, struct bio_fallback_crypt_ctx, work);
383 struct bio *bio = f_ctx->bio;
384 struct bio_crypt_ctx *bc = &f_ctx->crypt_ctx;
385 struct blk_crypto_keyslot *slot;
386 struct skcipher_request *ciph_req = NULL;
387 DECLARE_CRYPTO_WAIT(wait);
388 u64 curr_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
389 union blk_crypto_iv iv;
390 struct scatterlist sg;
391 struct bio_vec bv;
392 struct bvec_iter iter;
393 const int data_unit_size = bc->bc_key->crypto_cfg.data_unit_size;
394 unsigned int i;
395 blk_status_t blk_st;
396
397 /*
398 * Get a blk-crypto-fallback keyslot that contains a crypto_skcipher for
399 * this bio's algorithm and key.
400 */
401 blk_st = blk_crypto_get_keyslot(blk_crypto_fallback_profile,
402 bc->bc_key, &slot);
403 if (blk_st != BLK_STS_OK) {
404 bio->bi_status = blk_st;
405 goto out_no_keyslot;
406 }
407
408 /* and then allocate an skcipher_request for it */
409 if (!blk_crypto_fallback_alloc_cipher_req(slot, &ciph_req, &wait)) {
410 bio->bi_status = BLK_STS_RESOURCE;
411 goto out;
412 }
413
414 memcpy(curr_dun, bc->bc_dun, sizeof(curr_dun));
415 sg_init_table(&sg, 1);
416 skcipher_request_set_crypt(ciph_req, &sg, &sg, data_unit_size,
417 iv.bytes);
418
419 /* Decrypt each segment in the bio */
420 __bio_for_each_segment(bv, bio, iter, f_ctx->crypt_iter) {
421 struct page *page = bv.bv_page;
422
423 sg_set_page(&sg, page, data_unit_size, bv.bv_offset);
424
425 /* Decrypt each data unit in the segment */
426 for (i = 0; i < bv.bv_len; i += data_unit_size) {
427 blk_crypto_dun_to_iv(curr_dun, &iv);
428 if (crypto_wait_req(crypto_skcipher_decrypt(ciph_req),
429 &wait)) {
430 bio->bi_status = BLK_STS_IOERR;
431 goto out;
432 }
433 bio_crypt_dun_increment(curr_dun, 1);
434 sg.offset += data_unit_size;
435 }
436 }
437
438 out:
439 skcipher_request_free(ciph_req);
440 blk_crypto_put_keyslot(slot);
441 out_no_keyslot:
442 mempool_free(f_ctx, bio_fallback_crypt_ctx_pool);
443 bio_endio(bio);
444 }
445
446 /**
447 * blk_crypto_fallback_decrypt_endio - queue bio for fallback decryption
448 *
449 * @bio: the bio to queue
450 *
451 * Restore bi_private and bi_end_io, and queue the bio for decryption into a
452 * workqueue, since this function will be called from an atomic context.
453 */
blk_crypto_fallback_decrypt_endio(struct bio * bio)454 static void blk_crypto_fallback_decrypt_endio(struct bio *bio)
455 {
456 struct bio_fallback_crypt_ctx *f_ctx = bio->bi_private;
457
458 bio->bi_private = f_ctx->bi_private_orig;
459 bio->bi_end_io = f_ctx->bi_end_io_orig;
460
461 /* If there was an IO error, don't queue for decrypt. */
462 if (bio->bi_status) {
463 mempool_free(f_ctx, bio_fallback_crypt_ctx_pool);
464 bio_endio(bio);
465 return;
466 }
467
468 INIT_WORK(&f_ctx->work, blk_crypto_fallback_decrypt_bio);
469 f_ctx->bio = bio;
470 queue_work(blk_crypto_wq, &f_ctx->work);
471 }
472
473 /**
474 * blk_crypto_fallback_bio_prep - Prepare a bio to use fallback en/decryption
475 *
476 * @bio_ptr: pointer to the bio to prepare
477 *
478 * If bio is doing a WRITE operation, this splits the bio into two parts if it's
479 * too big (see blk_crypto_fallback_split_bio_if_needed()). It then allocates a
480 * bounce bio for the first part, encrypts it, and updates bio_ptr to point to
481 * the bounce bio.
482 *
483 * For a READ operation, we mark the bio for decryption by using bi_private and
484 * bi_end_io.
485 *
486 * In either case, this function will make the bio look like a regular bio (i.e.
487 * as if no encryption context was ever specified) for the purposes of the rest
488 * of the stack except for blk-integrity (blk-integrity and blk-crypto are not
489 * currently supported together).
490 *
491 * Return: true on success. Sets bio->bi_status and returns false on error.
492 */
blk_crypto_fallback_bio_prep(struct bio ** bio_ptr)493 bool blk_crypto_fallback_bio_prep(struct bio **bio_ptr)
494 {
495 struct bio *bio = *bio_ptr;
496 struct bio_crypt_ctx *bc = bio->bi_crypt_context;
497 struct bio_fallback_crypt_ctx *f_ctx;
498
499 if (WARN_ON_ONCE(!tfms_inited[bc->bc_key->crypto_cfg.crypto_mode])) {
500 /* User didn't call blk_crypto_start_using_key() first */
501 bio->bi_status = BLK_STS_IOERR;
502 return false;
503 }
504
505 if (!__blk_crypto_cfg_supported(blk_crypto_fallback_profile,
506 &bc->bc_key->crypto_cfg)) {
507 bio->bi_status = BLK_STS_NOTSUPP;
508 return false;
509 }
510
511 if (bio_data_dir(bio) == WRITE)
512 return blk_crypto_fallback_encrypt_bio(bio_ptr);
513
514 /*
515 * bio READ case: Set up a f_ctx in the bio's bi_private and set the
516 * bi_end_io appropriately to trigger decryption when the bio is ended.
517 */
518 f_ctx = mempool_alloc(bio_fallback_crypt_ctx_pool, GFP_NOIO);
519 f_ctx->crypt_ctx = *bc;
520 f_ctx->crypt_iter = bio->bi_iter;
521 f_ctx->bi_private_orig = bio->bi_private;
522 f_ctx->bi_end_io_orig = bio->bi_end_io;
523 bio->bi_private = (void *)f_ctx;
524 bio->bi_end_io = blk_crypto_fallback_decrypt_endio;
525 bio_crypt_free_ctx(bio);
526
527 return true;
528 }
529
blk_crypto_fallback_evict_key(const struct blk_crypto_key * key)530 int blk_crypto_fallback_evict_key(const struct blk_crypto_key *key)
531 {
532 return __blk_crypto_evict_key(blk_crypto_fallback_profile, key);
533 }
534
535 static bool blk_crypto_fallback_inited;
blk_crypto_fallback_init(void)536 static int blk_crypto_fallback_init(void)
537 {
538 int i;
539 int err;
540
541 if (blk_crypto_fallback_inited)
542 return 0;
543
544 get_random_bytes(blank_key, sizeof(blank_key));
545
546 err = bioset_init(&crypto_bio_split, 64, 0, 0);
547 if (err)
548 goto out;
549
550 /* Dynamic allocation is needed because of lockdep_register_key(). */
551 blk_crypto_fallback_profile =
552 kzalloc(sizeof(*blk_crypto_fallback_profile), GFP_KERNEL);
553 if (!blk_crypto_fallback_profile) {
554 err = -ENOMEM;
555 goto fail_free_bioset;
556 }
557
558 err = blk_crypto_profile_init(blk_crypto_fallback_profile,
559 blk_crypto_num_keyslots);
560 if (err)
561 goto fail_free_profile;
562 err = -ENOMEM;
563
564 blk_crypto_fallback_profile->ll_ops = blk_crypto_fallback_ll_ops;
565 blk_crypto_fallback_profile->max_dun_bytes_supported = BLK_CRYPTO_MAX_IV_SIZE;
566 blk_crypto_fallback_profile->key_types_supported = BLK_CRYPTO_KEY_TYPE_STANDARD;
567
568 /* All blk-crypto modes have a crypto API fallback. */
569 for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++)
570 blk_crypto_fallback_profile->modes_supported[i] = 0xFFFFFFFF;
571 blk_crypto_fallback_profile->modes_supported[BLK_ENCRYPTION_MODE_INVALID] = 0;
572
573 blk_crypto_wq = alloc_workqueue("blk_crypto_wq",
574 WQ_UNBOUND | WQ_HIGHPRI |
575 WQ_MEM_RECLAIM, num_online_cpus());
576 if (!blk_crypto_wq)
577 goto fail_destroy_profile;
578
579 blk_crypto_keyslots = kcalloc(blk_crypto_num_keyslots,
580 sizeof(blk_crypto_keyslots[0]),
581 GFP_KERNEL);
582 if (!blk_crypto_keyslots)
583 goto fail_free_wq;
584
585 blk_crypto_bounce_page_pool =
586 mempool_create_page_pool(num_prealloc_bounce_pg, 0);
587 if (!blk_crypto_bounce_page_pool)
588 goto fail_free_keyslots;
589
590 bio_fallback_crypt_ctx_cache = KMEM_CACHE(bio_fallback_crypt_ctx, 0);
591 if (!bio_fallback_crypt_ctx_cache)
592 goto fail_free_bounce_page_pool;
593
594 bio_fallback_crypt_ctx_pool =
595 mempool_create_slab_pool(num_prealloc_fallback_crypt_ctxs,
596 bio_fallback_crypt_ctx_cache);
597 if (!bio_fallback_crypt_ctx_pool)
598 goto fail_free_crypt_ctx_cache;
599
600 blk_crypto_fallback_inited = true;
601
602 return 0;
603 fail_free_crypt_ctx_cache:
604 kmem_cache_destroy(bio_fallback_crypt_ctx_cache);
605 fail_free_bounce_page_pool:
606 mempool_destroy(blk_crypto_bounce_page_pool);
607 fail_free_keyslots:
608 kfree(blk_crypto_keyslots);
609 fail_free_wq:
610 destroy_workqueue(blk_crypto_wq);
611 fail_destroy_profile:
612 blk_crypto_profile_destroy(blk_crypto_fallback_profile);
613 fail_free_profile:
614 kfree(blk_crypto_fallback_profile);
615 fail_free_bioset:
616 bioset_exit(&crypto_bio_split);
617 out:
618 return err;
619 }
620
621 /*
622 * Prepare blk-crypto-fallback for the specified crypto mode.
623 * Returns -ENOPKG if the needed crypto API support is missing.
624 */
blk_crypto_fallback_start_using_mode(enum blk_crypto_mode_num mode_num)625 int blk_crypto_fallback_start_using_mode(enum blk_crypto_mode_num mode_num)
626 {
627 const char *cipher_str = blk_crypto_modes[mode_num].cipher_str;
628 struct blk_crypto_fallback_keyslot *slotp;
629 unsigned int i;
630 int err = 0;
631
632 /*
633 * Fast path
634 * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num]
635 * for each i are visible before we try to access them.
636 */
637 if (likely(smp_load_acquire(&tfms_inited[mode_num])))
638 return 0;
639
640 mutex_lock(&tfms_init_lock);
641 if (tfms_inited[mode_num])
642 goto out;
643
644 err = blk_crypto_fallback_init();
645 if (err)
646 goto out;
647
648 for (i = 0; i < blk_crypto_num_keyslots; i++) {
649 slotp = &blk_crypto_keyslots[i];
650 slotp->tfms[mode_num] = crypto_alloc_skcipher(cipher_str, 0, 0);
651 if (IS_ERR(slotp->tfms[mode_num])) {
652 err = PTR_ERR(slotp->tfms[mode_num]);
653 if (err == -ENOENT) {
654 pr_warn_once("Missing crypto API support for \"%s\"\n",
655 cipher_str);
656 err = -ENOPKG;
657 }
658 slotp->tfms[mode_num] = NULL;
659 goto out_free_tfms;
660 }
661
662 crypto_skcipher_set_flags(slotp->tfms[mode_num],
663 CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
664 }
665
666 /*
667 * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num]
668 * for each i are visible before we set tfms_inited[mode_num].
669 */
670 smp_store_release(&tfms_inited[mode_num], true);
671 goto out;
672
673 out_free_tfms:
674 for (i = 0; i < blk_crypto_num_keyslots; i++) {
675 slotp = &blk_crypto_keyslots[i];
676 crypto_free_skcipher(slotp->tfms[mode_num]);
677 slotp->tfms[mode_num] = NULL;
678 }
679 out:
680 mutex_unlock(&tfms_init_lock);
681 return err;
682 }
683