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