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_iter.bi_sector = bio_src->bi_iter.bi_sector;
176 bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
177
178 bio_for_each_segment(bv, bio_src, iter)
179 bio->bi_io_vec[bio->bi_vcnt++] = bv;
180
181 bio_clone_blkg_association(bio, bio_src);
182
183 bio_clone_skip_dm_default_key(bio, bio_src);
184
185 return bio;
186 }
187
188 static bool
blk_crypto_fallback_alloc_cipher_req(struct blk_crypto_keyslot * slot,struct skcipher_request ** ciph_req_ret,struct crypto_wait * wait)189 blk_crypto_fallback_alloc_cipher_req(struct blk_crypto_keyslot *slot,
190 struct skcipher_request **ciph_req_ret,
191 struct crypto_wait *wait)
192 {
193 struct skcipher_request *ciph_req;
194 const struct blk_crypto_fallback_keyslot *slotp;
195 int keyslot_idx = blk_crypto_keyslot_index(slot);
196
197 slotp = &blk_crypto_keyslots[keyslot_idx];
198 ciph_req = skcipher_request_alloc(slotp->tfms[slotp->crypto_mode],
199 GFP_NOIO);
200 if (!ciph_req)
201 return false;
202
203 skcipher_request_set_callback(ciph_req,
204 CRYPTO_TFM_REQ_MAY_BACKLOG |
205 CRYPTO_TFM_REQ_MAY_SLEEP,
206 crypto_req_done, wait);
207 *ciph_req_ret = ciph_req;
208
209 return true;
210 }
211
blk_crypto_fallback_split_bio_if_needed(struct bio ** bio_ptr)212 static bool blk_crypto_fallback_split_bio_if_needed(struct bio **bio_ptr)
213 {
214 struct bio *bio = *bio_ptr;
215 unsigned int i = 0;
216 unsigned int num_sectors = 0;
217 struct bio_vec bv;
218 struct bvec_iter iter;
219
220 bio_for_each_segment(bv, bio, iter) {
221 num_sectors += bv.bv_len >> SECTOR_SHIFT;
222 if (++i == BIO_MAX_VECS)
223 break;
224 }
225 if (num_sectors < bio_sectors(bio)) {
226 struct bio *split_bio;
227
228 split_bio = bio_split(bio, num_sectors, GFP_NOIO,
229 &crypto_bio_split);
230 if (!split_bio) {
231 bio->bi_status = BLK_STS_RESOURCE;
232 return false;
233 }
234 bio_chain(split_bio, bio);
235 submit_bio_noacct(bio);
236 *bio_ptr = split_bio;
237 }
238
239 return true;
240 }
241
242 union blk_crypto_iv {
243 __le64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
244 u8 bytes[BLK_CRYPTO_MAX_IV_SIZE];
245 };
246
blk_crypto_dun_to_iv(const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],union blk_crypto_iv * iv)247 static void blk_crypto_dun_to_iv(const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
248 union blk_crypto_iv *iv)
249 {
250 int i;
251
252 for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++)
253 iv->dun[i] = cpu_to_le64(dun[i]);
254 }
255
256 /*
257 * The crypto API fallback's encryption routine.
258 * Allocate a bounce bio for encryption, encrypt the input bio using crypto API,
259 * and replace *bio_ptr with the bounce bio. May split input bio if it's too
260 * large. Returns true on success. Returns false and sets bio->bi_status on
261 * error.
262 */
blk_crypto_fallback_encrypt_bio(struct bio ** bio_ptr)263 static bool blk_crypto_fallback_encrypt_bio(struct bio **bio_ptr)
264 {
265 struct bio *src_bio, *enc_bio;
266 struct bio_crypt_ctx *bc;
267 struct blk_crypto_keyslot *slot;
268 int data_unit_size;
269 struct skcipher_request *ciph_req = NULL;
270 DECLARE_CRYPTO_WAIT(wait);
271 u64 curr_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
272 struct scatterlist src, dst;
273 union blk_crypto_iv iv;
274 unsigned int i, j;
275 bool ret = false;
276 blk_status_t blk_st;
277
278 /* Split the bio if it's too big for single page bvec */
279 if (!blk_crypto_fallback_split_bio_if_needed(bio_ptr))
280 return false;
281
282 src_bio = *bio_ptr;
283 bc = src_bio->bi_crypt_context;
284 data_unit_size = bc->bc_key->crypto_cfg.data_unit_size;
285
286 /* Allocate bounce bio for encryption */
287 enc_bio = blk_crypto_fallback_clone_bio(src_bio);
288 if (!enc_bio) {
289 src_bio->bi_status = BLK_STS_RESOURCE;
290 return false;
291 }
292
293 /*
294 * Get a blk-crypto-fallback keyslot that contains a crypto_skcipher for
295 * this bio's algorithm and key.
296 */
297 blk_st = blk_crypto_get_keyslot(blk_crypto_fallback_profile,
298 bc->bc_key, &slot);
299 if (blk_st != BLK_STS_OK) {
300 src_bio->bi_status = blk_st;
301 goto out_put_enc_bio;
302 }
303
304 /* and then allocate an skcipher_request for it */
305 if (!blk_crypto_fallback_alloc_cipher_req(slot, &ciph_req, &wait)) {
306 src_bio->bi_status = BLK_STS_RESOURCE;
307 goto out_release_keyslot;
308 }
309
310 memcpy(curr_dun, bc->bc_dun, sizeof(curr_dun));
311 sg_init_table(&src, 1);
312 sg_init_table(&dst, 1);
313
314 skcipher_request_set_crypt(ciph_req, &src, &dst, data_unit_size,
315 iv.bytes);
316
317 /* Encrypt each page in the bounce bio */
318 for (i = 0; i < enc_bio->bi_vcnt; i++) {
319 struct bio_vec *enc_bvec = &enc_bio->bi_io_vec[i];
320 struct page *plaintext_page = enc_bvec->bv_page;
321 struct page *ciphertext_page =
322 mempool_alloc(blk_crypto_bounce_page_pool, GFP_NOIO);
323
324 enc_bvec->bv_page = ciphertext_page;
325
326 if (!ciphertext_page) {
327 src_bio->bi_status = BLK_STS_RESOURCE;
328 goto out_free_bounce_pages;
329 }
330
331 sg_set_page(&src, plaintext_page, data_unit_size,
332 enc_bvec->bv_offset);
333 sg_set_page(&dst, ciphertext_page, data_unit_size,
334 enc_bvec->bv_offset);
335
336 /* Encrypt each data unit in this page */
337 for (j = 0; j < enc_bvec->bv_len; j += data_unit_size) {
338 blk_crypto_dun_to_iv(curr_dun, &iv);
339 if (crypto_wait_req(crypto_skcipher_encrypt(ciph_req),
340 &wait)) {
341 i++;
342 src_bio->bi_status = BLK_STS_IOERR;
343 goto out_free_bounce_pages;
344 }
345 bio_crypt_dun_increment(curr_dun, 1);
346 src.offset += data_unit_size;
347 dst.offset += data_unit_size;
348 }
349 }
350
351 enc_bio->bi_private = src_bio;
352 enc_bio->bi_end_io = blk_crypto_fallback_encrypt_endio;
353 *bio_ptr = enc_bio;
354 ret = true;
355
356 enc_bio = NULL;
357 goto out_free_ciph_req;
358
359 out_free_bounce_pages:
360 while (i > 0)
361 mempool_free(enc_bio->bi_io_vec[--i].bv_page,
362 blk_crypto_bounce_page_pool);
363 out_free_ciph_req:
364 skcipher_request_free(ciph_req);
365 out_release_keyslot:
366 blk_crypto_put_keyslot(slot);
367 out_put_enc_bio:
368 if (enc_bio)
369 bio_uninit(enc_bio);
370 kfree(enc_bio);
371 return ret;
372 }
373
374 /*
375 * The crypto API fallback's main decryption routine.
376 * Decrypts input bio in place, and calls bio_endio on the bio.
377 */
blk_crypto_fallback_decrypt_bio(struct work_struct * work)378 static void blk_crypto_fallback_decrypt_bio(struct work_struct *work)
379 {
380 struct bio_fallback_crypt_ctx *f_ctx =
381 container_of(work, struct bio_fallback_crypt_ctx, work);
382 struct bio *bio = f_ctx->bio;
383 struct bio_crypt_ctx *bc = &f_ctx->crypt_ctx;
384 struct blk_crypto_keyslot *slot;
385 struct skcipher_request *ciph_req = NULL;
386 DECLARE_CRYPTO_WAIT(wait);
387 u64 curr_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
388 union blk_crypto_iv iv;
389 struct scatterlist sg;
390 struct bio_vec bv;
391 struct bvec_iter iter;
392 const int data_unit_size = bc->bc_key->crypto_cfg.data_unit_size;
393 unsigned int i;
394 blk_status_t blk_st;
395
396 /*
397 * Get a blk-crypto-fallback keyslot that contains a crypto_skcipher for
398 * this bio's algorithm and key.
399 */
400 blk_st = blk_crypto_get_keyslot(blk_crypto_fallback_profile,
401 bc->bc_key, &slot);
402 if (blk_st != BLK_STS_OK) {
403 bio->bi_status = blk_st;
404 goto out_no_keyslot;
405 }
406
407 /* and then allocate an skcipher_request for it */
408 if (!blk_crypto_fallback_alloc_cipher_req(slot, &ciph_req, &wait)) {
409 bio->bi_status = BLK_STS_RESOURCE;
410 goto out;
411 }
412
413 memcpy(curr_dun, bc->bc_dun, sizeof(curr_dun));
414 sg_init_table(&sg, 1);
415 skcipher_request_set_crypt(ciph_req, &sg, &sg, data_unit_size,
416 iv.bytes);
417
418 /* Decrypt each segment in the bio */
419 __bio_for_each_segment(bv, bio, iter, f_ctx->crypt_iter) {
420 struct page *page = bv.bv_page;
421
422 sg_set_page(&sg, page, data_unit_size, bv.bv_offset);
423
424 /* Decrypt each data unit in the segment */
425 for (i = 0; i < bv.bv_len; i += data_unit_size) {
426 blk_crypto_dun_to_iv(curr_dun, &iv);
427 if (crypto_wait_req(crypto_skcipher_decrypt(ciph_req),
428 &wait)) {
429 bio->bi_status = BLK_STS_IOERR;
430 goto out;
431 }
432 bio_crypt_dun_increment(curr_dun, 1);
433 sg.offset += data_unit_size;
434 }
435 }
436
437 out:
438 skcipher_request_free(ciph_req);
439 blk_crypto_put_keyslot(slot);
440 out_no_keyslot:
441 mempool_free(f_ctx, bio_fallback_crypt_ctx_pool);
442 bio_endio(bio);
443 }
444
445 /**
446 * blk_crypto_fallback_decrypt_endio - queue bio for fallback decryption
447 *
448 * @bio: the bio to queue
449 *
450 * Restore bi_private and bi_end_io, and queue the bio for decryption into a
451 * workqueue, since this function will be called from an atomic context.
452 */
blk_crypto_fallback_decrypt_endio(struct bio * bio)453 static void blk_crypto_fallback_decrypt_endio(struct bio *bio)
454 {
455 struct bio_fallback_crypt_ctx *f_ctx = bio->bi_private;
456
457 bio->bi_private = f_ctx->bi_private_orig;
458 bio->bi_end_io = f_ctx->bi_end_io_orig;
459
460 /* If there was an IO error, don't queue for decrypt. */
461 if (bio->bi_status) {
462 mempool_free(f_ctx, bio_fallback_crypt_ctx_pool);
463 bio_endio(bio);
464 return;
465 }
466
467 INIT_WORK(&f_ctx->work, blk_crypto_fallback_decrypt_bio);
468 f_ctx->bio = bio;
469 queue_work(blk_crypto_wq, &f_ctx->work);
470 }
471
472 /**
473 * blk_crypto_fallback_bio_prep - Prepare a bio to use fallback en/decryption
474 *
475 * @bio_ptr: pointer to the bio to prepare
476 *
477 * If bio is doing a WRITE operation, this splits the bio into two parts if it's
478 * too big (see blk_crypto_fallback_split_bio_if_needed()). It then allocates a
479 * bounce bio for the first part, encrypts it, and updates bio_ptr to point to
480 * the bounce bio.
481 *
482 * For a READ operation, we mark the bio for decryption by using bi_private and
483 * bi_end_io.
484 *
485 * In either case, this function will make the bio look like a regular bio (i.e.
486 * as if no encryption context was ever specified) for the purposes of the rest
487 * of the stack except for blk-integrity (blk-integrity and blk-crypto are not
488 * currently supported together).
489 *
490 * Return: true on success. Sets bio->bi_status and returns false on error.
491 */
blk_crypto_fallback_bio_prep(struct bio ** bio_ptr)492 bool blk_crypto_fallback_bio_prep(struct bio **bio_ptr)
493 {
494 struct bio *bio = *bio_ptr;
495 struct bio_crypt_ctx *bc = bio->bi_crypt_context;
496 struct bio_fallback_crypt_ctx *f_ctx;
497
498 if (WARN_ON_ONCE(!tfms_inited[bc->bc_key->crypto_cfg.crypto_mode])) {
499 /* User didn't call blk_crypto_start_using_key() first */
500 bio->bi_status = BLK_STS_IOERR;
501 return false;
502 }
503
504 if (!__blk_crypto_cfg_supported(blk_crypto_fallback_profile,
505 &bc->bc_key->crypto_cfg)) {
506 bio->bi_status = BLK_STS_NOTSUPP;
507 return false;
508 }
509
510 if (bio_data_dir(bio) == WRITE)
511 return blk_crypto_fallback_encrypt_bio(bio_ptr);
512
513 /*
514 * bio READ case: Set up a f_ctx in the bio's bi_private and set the
515 * bi_end_io appropriately to trigger decryption when the bio is ended.
516 */
517 f_ctx = mempool_alloc(bio_fallback_crypt_ctx_pool, GFP_NOIO);
518 f_ctx->crypt_ctx = *bc;
519 f_ctx->crypt_iter = bio->bi_iter;
520 f_ctx->bi_private_orig = bio->bi_private;
521 f_ctx->bi_end_io_orig = bio->bi_end_io;
522 bio->bi_private = (void *)f_ctx;
523 bio->bi_end_io = blk_crypto_fallback_decrypt_endio;
524 bio_crypt_free_ctx(bio);
525
526 return true;
527 }
528
blk_crypto_fallback_evict_key(const struct blk_crypto_key * key)529 int blk_crypto_fallback_evict_key(const struct blk_crypto_key *key)
530 {
531 return __blk_crypto_evict_key(blk_crypto_fallback_profile, key);
532 }
533
534 static bool blk_crypto_fallback_inited;
blk_crypto_fallback_init(void)535 static int blk_crypto_fallback_init(void)
536 {
537 int i;
538 int err;
539
540 if (blk_crypto_fallback_inited)
541 return 0;
542
543 get_random_bytes(blank_key, sizeof(blank_key));
544
545 err = bioset_init(&crypto_bio_split, 64, 0, 0);
546 if (err)
547 goto out;
548
549 /* Dynamic allocation is needed because of lockdep_register_key(). */
550 blk_crypto_fallback_profile =
551 kzalloc(sizeof(*blk_crypto_fallback_profile), GFP_KERNEL);
552 if (!blk_crypto_fallback_profile) {
553 err = -ENOMEM;
554 goto fail_free_bioset;
555 }
556
557 err = blk_crypto_profile_init(blk_crypto_fallback_profile,
558 blk_crypto_num_keyslots);
559 if (err)
560 goto fail_free_profile;
561 err = -ENOMEM;
562
563 blk_crypto_fallback_profile->ll_ops = blk_crypto_fallback_ll_ops;
564 blk_crypto_fallback_profile->max_dun_bytes_supported = BLK_CRYPTO_MAX_IV_SIZE;
565 blk_crypto_fallback_profile->key_types_supported = BLK_CRYPTO_KEY_TYPE_STANDARD;
566
567 /* All blk-crypto modes have a crypto API fallback. */
568 for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++)
569 blk_crypto_fallback_profile->modes_supported[i] = 0xFFFFFFFF;
570 blk_crypto_fallback_profile->modes_supported[BLK_ENCRYPTION_MODE_INVALID] = 0;
571
572 blk_crypto_wq = alloc_workqueue("blk_crypto_wq",
573 WQ_UNBOUND | WQ_HIGHPRI |
574 WQ_MEM_RECLAIM, num_online_cpus());
575 if (!blk_crypto_wq)
576 goto fail_destroy_profile;
577
578 blk_crypto_keyslots = kcalloc(blk_crypto_num_keyslots,
579 sizeof(blk_crypto_keyslots[0]),
580 GFP_KERNEL);
581 if (!blk_crypto_keyslots)
582 goto fail_free_wq;
583
584 blk_crypto_bounce_page_pool =
585 mempool_create_page_pool(num_prealloc_bounce_pg, 0);
586 if (!blk_crypto_bounce_page_pool)
587 goto fail_free_keyslots;
588
589 bio_fallback_crypt_ctx_cache = KMEM_CACHE(bio_fallback_crypt_ctx, 0);
590 if (!bio_fallback_crypt_ctx_cache)
591 goto fail_free_bounce_page_pool;
592
593 bio_fallback_crypt_ctx_pool =
594 mempool_create_slab_pool(num_prealloc_fallback_crypt_ctxs,
595 bio_fallback_crypt_ctx_cache);
596 if (!bio_fallback_crypt_ctx_pool)
597 goto fail_free_crypt_ctx_cache;
598
599 blk_crypto_fallback_inited = true;
600
601 return 0;
602 fail_free_crypt_ctx_cache:
603 kmem_cache_destroy(bio_fallback_crypt_ctx_cache);
604 fail_free_bounce_page_pool:
605 mempool_destroy(blk_crypto_bounce_page_pool);
606 fail_free_keyslots:
607 kfree(blk_crypto_keyslots);
608 fail_free_wq:
609 destroy_workqueue(blk_crypto_wq);
610 fail_destroy_profile:
611 blk_crypto_profile_destroy(blk_crypto_fallback_profile);
612 fail_free_profile:
613 kfree(blk_crypto_fallback_profile);
614 fail_free_bioset:
615 bioset_exit(&crypto_bio_split);
616 out:
617 return err;
618 }
619
620 /*
621 * Prepare blk-crypto-fallback for the specified crypto mode.
622 * Returns -ENOPKG if the needed crypto API support is missing.
623 */
blk_crypto_fallback_start_using_mode(enum blk_crypto_mode_num mode_num)624 int blk_crypto_fallback_start_using_mode(enum blk_crypto_mode_num mode_num)
625 {
626 const char *cipher_str = blk_crypto_modes[mode_num].cipher_str;
627 struct blk_crypto_fallback_keyslot *slotp;
628 unsigned int i;
629 int err = 0;
630
631 /*
632 * Fast path
633 * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num]
634 * for each i are visible before we try to access them.
635 */
636 if (likely(smp_load_acquire(&tfms_inited[mode_num])))
637 return 0;
638
639 mutex_lock(&tfms_init_lock);
640 if (tfms_inited[mode_num])
641 goto out;
642
643 err = blk_crypto_fallback_init();
644 if (err)
645 goto out;
646
647 for (i = 0; i < blk_crypto_num_keyslots; i++) {
648 slotp = &blk_crypto_keyslots[i];
649 slotp->tfms[mode_num] = crypto_alloc_skcipher(cipher_str, 0, 0);
650 if (IS_ERR(slotp->tfms[mode_num])) {
651 err = PTR_ERR(slotp->tfms[mode_num]);
652 if (err == -ENOENT) {
653 pr_warn_once("Missing crypto API support for \"%s\"\n",
654 cipher_str);
655 err = -ENOPKG;
656 }
657 slotp->tfms[mode_num] = NULL;
658 goto out_free_tfms;
659 }
660
661 crypto_skcipher_set_flags(slotp->tfms[mode_num],
662 CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
663 }
664
665 /*
666 * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num]
667 * for each i are visible before we set tfms_inited[mode_num].
668 */
669 smp_store_release(&tfms_inited[mode_num], true);
670 goto out;
671
672 out_free_tfms:
673 for (i = 0; i < blk_crypto_num_keyslots; i++) {
674 slotp = &blk_crypto_keyslots[i];
675 crypto_free_skcipher(slotp->tfms[mode_num]);
676 slotp->tfms[mode_num] = NULL;
677 }
678 out:
679 mutex_unlock(&tfms_init_lock);
680 return err;
681 }
682