projects/linux·blob assoc-array-fixes · refs

676 lines · 19.8 KiB

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
25static unsigned int num_prealloc_bounce_pg = BIO_MAX_VECS;
26module_param(num_prealloc_bounce_pg, uint, 0);
27MODULE_PARM_DESC(num_prealloc_bounce_pg,
28 "Number of preallocated bounce pages for the blk-crypto crypto API fallback");
29
30static unsigned int blk_crypto_num_keyslots = 100;
31module_param_named(num_keyslots, blk_crypto_num_keyslots, uint, 0);
32MODULE_PARM_DESC(num_keyslots,
33 "Number of keyslots for the blk-crypto crypto API fallback");
34
35static unsigned int num_prealloc_fallback_crypt_ctxs = 128;
36module_param(num_prealloc_fallback_crypt_ctxs, uint, 0);
37MODULE_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
40struct 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
61static struct kmem_cache *bio_fallback_crypt_ctx_cache;
62static 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 */
73static DEFINE_MUTEX(tfms_init_lock);
74static bool tfms_inited[BLK_ENCRYPTION_MODE_MAX];
75
76static struct blk_crypto_fallback_keyslot {
77 enum blk_crypto_mode_num crypto_mode;
78 struct crypto_sync_skcipher *tfms[BLK_ENCRYPTION_MODE_MAX];
79} *blk_crypto_keyslots;
80
81static struct blk_crypto_profile *blk_crypto_fallback_profile;
82static struct workqueue_struct *blk_crypto_wq;
83static mempool_t *blk_crypto_bounce_page_pool;
84static struct bio_set enc_bio_set;
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 */
90static u8 blank_key[BLK_CRYPTO_MAX_RAW_KEY_SIZE];
91
92static 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_sync_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
107static int
108blk_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_sync_skcipher_setkey(slotp->tfms[crypto_mode], key->bytes,
123 key->size);
124 if (err) {
125 blk_crypto_fallback_evict_keyslot(slot);
126 return err;
127 }
128 return 0;
129}
130
131static 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
139static 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
144static void blk_crypto_fallback_encrypt_endio(struct bio *enc_bio)
145{
146 struct bio *src_bio = enc_bio->bi_private;
147 struct page **pages = (struct page **)enc_bio->bi_io_vec;
148 struct bio_vec *bv;
149 unsigned int i;
150
151 /*
152 * Use the same trick as the alloc side to avoid the need for an extra
153 * pages array.
154 */
155 bio_for_each_bvec_all(bv, enc_bio, i)
156 pages[i] = bv->bv_page;
157
158 i = mempool_free_bulk(blk_crypto_bounce_page_pool, (void **)pages,
159 enc_bio->bi_vcnt);
160 if (i < enc_bio->bi_vcnt)
161 release_pages(pages + i, enc_bio->bi_vcnt - i);
162
163 if (enc_bio->bi_status)
164 cmpxchg(&src_bio->bi_status, 0, enc_bio->bi_status);
165
166 bio_put(enc_bio);
167 bio_endio(src_bio);
168}
169
170#define PAGE_PTRS_PER_BVEC (sizeof(struct bio_vec) / sizeof(struct page *))
171
172static struct bio *blk_crypto_alloc_enc_bio(struct bio *bio_src,
173 unsigned int nr_segs, struct page ***pages_ret)
174{
175 unsigned int memflags = memalloc_noio_save();
176 unsigned int nr_allocated;
177 struct page **pages;
178 struct bio *bio;
179
180 bio = bio_alloc_bioset(bio_src->bi_bdev, nr_segs, bio_src->bi_opf,
181 GFP_NOIO, &enc_bio_set);
182 if (bio_flagged(bio_src, BIO_REMAPPED))
183 bio_set_flag(bio, BIO_REMAPPED);
184 bio->bi_private = bio_src;
185 bio->bi_end_io = blk_crypto_fallback_encrypt_endio;
186 bio->bi_ioprio = bio_src->bi_ioprio;
187 bio->bi_write_hint = bio_src->bi_write_hint;
188 bio->bi_write_stream = bio_src->bi_write_stream;
189 bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
190 bio_clone_blkg_association(bio, bio_src);
191
192 /*
193 * Move page array up in the allocated memory for the bio vecs as far as
194 * possible so that we can start filling biovecs from the beginning
195 * without overwriting the temporary page array.
196 */
197 static_assert(PAGE_PTRS_PER_BVEC > 1);
198 pages = (struct page **)bio->bi_io_vec;
199 pages += nr_segs * (PAGE_PTRS_PER_BVEC - 1);
200
201 /*
202 * Try a bulk allocation first. This might not fill all allocated
203 * pages, but we'll fix that up later in mempool_alloc_bulk.
204 *
205 * Note: alloc_pages_bulk needs the array to be zeroed, as it assumes
206 * any non-zero slot already contains a valid allocation.
207 */
208 memset(pages, 0, sizeof(struct page *) * nr_segs);
209 nr_allocated = alloc_pages_bulk(GFP_KERNEL, nr_segs, pages);
210 if (nr_allocated < nr_segs)
211 mempool_alloc_bulk(blk_crypto_bounce_page_pool,
212 (void **)pages + nr_allocated,
213 nr_segs - nr_allocated);
214 memalloc_noio_restore(memflags);
215 *pages_ret = pages;
216 return bio;
217}
218
219static struct crypto_sync_skcipher *
220blk_crypto_fallback_tfm(struct blk_crypto_keyslot *slot)
221{
222 const struct blk_crypto_fallback_keyslot *slotp =
223 &blk_crypto_keyslots[blk_crypto_keyslot_index(slot)];
224
225 return slotp->tfms[slotp->crypto_mode];
226}
227
228union blk_crypto_iv {
229 __le64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
230 u8 bytes[BLK_CRYPTO_MAX_IV_SIZE];
231};
232
233static void blk_crypto_dun_to_iv(const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
234 union blk_crypto_iv *iv)
235{
236 int i;
237
238 for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++)
239 iv->dun[i] = cpu_to_le64(dun[i]);
240}
241
242static void __blk_crypto_fallback_encrypt_bio(struct bio *src_bio,
243 struct crypto_sync_skcipher *tfm)
244{
245 struct bio_crypt_ctx *bc = src_bio->bi_crypt_context;
246 int data_unit_size = bc->bc_key->crypto_cfg.data_unit_size;
247 SYNC_SKCIPHER_REQUEST_ON_STACK(ciph_req, tfm);
248 u64 curr_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
249 struct scatterlist src, dst;
250 union blk_crypto_iv iv;
251 unsigned int nr_enc_pages, enc_idx;
252 struct page **enc_pages;
253 struct bio *enc_bio;
254 unsigned int i;
255
256 skcipher_request_set_callback(ciph_req,
257 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
258 NULL, NULL);
259
260 memcpy(curr_dun, bc->bc_dun, sizeof(curr_dun));
261 sg_init_table(&src, 1);
262 sg_init_table(&dst, 1);
263
264 skcipher_request_set_crypt(ciph_req, &src, &dst, data_unit_size,
265 iv.bytes);
266
267 /*
268 * Encrypt each page in the source bio. Because the source bio could
269 * have bio_vecs that span more than a single page, but the encrypted
270 * bios are limited to a single page per bio_vec, this can generate
271 * more than a single encrypted bio per source bio.
272 */
273new_bio:
274 nr_enc_pages = min(bio_segments(src_bio), BIO_MAX_VECS);
275 enc_bio = blk_crypto_alloc_enc_bio(src_bio, nr_enc_pages, &enc_pages);
276 enc_idx = 0;
277 for (;;) {
278 struct bio_vec src_bv =
279 bio_iter_iovec(src_bio, src_bio->bi_iter);
280 struct page *enc_page = enc_pages[enc_idx];
281
282 if (!IS_ALIGNED(src_bv.bv_len | src_bv.bv_offset,
283 data_unit_size)) {
284 enc_bio->bi_status = BLK_STS_INVAL;
285 goto out_free_enc_bio;
286 }
287
288 __bio_add_page(enc_bio, enc_page, src_bv.bv_len,
289 src_bv.bv_offset);
290
291 sg_set_page(&src, src_bv.bv_page, data_unit_size,
292 src_bv.bv_offset);
293 sg_set_page(&dst, enc_page, data_unit_size, src_bv.bv_offset);
294
295 /*
296 * Increment the index now that the encrypted page is added to
297 * the bio. This is important for the error unwind path.
298 */
299 enc_idx++;
300
301 /*
302 * Encrypt each data unit in this page.
303 */
304 for (i = 0; i < src_bv.bv_len; i += data_unit_size) {
305 blk_crypto_dun_to_iv(curr_dun, &iv);
306 if (crypto_skcipher_encrypt(ciph_req)) {
307 enc_bio->bi_status = BLK_STS_IOERR;
308 goto out_free_enc_bio;
309 }
310 bio_crypt_dun_increment(curr_dun, 1);
311 src.offset += data_unit_size;
312 dst.offset += data_unit_size;
313 }
314
315 bio_advance_iter_single(src_bio, &src_bio->bi_iter,
316 src_bv.bv_len);
317 if (!src_bio->bi_iter.bi_size)
318 break;
319
320 if (enc_idx == nr_enc_pages) {
321 /*
322 * For each additional encrypted bio submitted,
323 * increment the source bio's remaining count. Each
324 * encrypted bio's completion handler calls bio_endio on
325 * the source bio, so this keeps the source bio from
326 * completing until the last encrypted bio does.
327 */
328 bio_inc_remaining(src_bio);
329 submit_bio(enc_bio);
330 goto new_bio;
331 }
332 }
333
334 submit_bio(enc_bio);
335 return;
336
337out_free_enc_bio:
338 /*
339 * Add the remaining pages to the bio so that the normal completion path
340 * in blk_crypto_fallback_encrypt_endio frees them. The exact data
341 * layout does not matter for that, so don't bother iterating the source
342 * bio.
343 */
344 for (; enc_idx < nr_enc_pages; enc_idx++)
345 __bio_add_page(enc_bio, enc_pages[enc_idx], PAGE_SIZE, 0);
346 bio_endio(enc_bio);
347}
348
349/*
350 * The crypto API fallback's encryption routine.
351 *
352 * Allocate one or more bios for encryption, encrypt the input bio using the
353 * crypto API, and submit the encrypted bios. Sets bio->bi_status and
354 * completes the source bio on error
355 */
356static void blk_crypto_fallback_encrypt_bio(struct bio *src_bio)
357{
358 struct bio_crypt_ctx *bc = src_bio->bi_crypt_context;
359 struct blk_crypto_keyslot *slot;
360 blk_status_t status;
361
362 status = blk_crypto_get_keyslot(blk_crypto_fallback_profile,
363 bc->bc_key, &slot);
364 if (status != BLK_STS_OK) {
365 bio_endio_status(src_bio, status);
366 return;
367 }
368 __blk_crypto_fallback_encrypt_bio(src_bio,
369 blk_crypto_fallback_tfm(slot));
370 blk_crypto_put_keyslot(slot);
371}
372
373static blk_status_t __blk_crypto_fallback_decrypt_bio(struct bio *bio,
374 struct bio_crypt_ctx *bc, struct bvec_iter iter,
375 struct crypto_sync_skcipher *tfm)
376{
377 SYNC_SKCIPHER_REQUEST_ON_STACK(ciph_req, tfm);
378 u64 curr_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
379 union blk_crypto_iv iv;
380 struct scatterlist sg;
381 struct bio_vec bv;
382 const int data_unit_size = bc->bc_key->crypto_cfg.data_unit_size;
383 unsigned int i;
384
385 skcipher_request_set_callback(ciph_req,
386 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
387 NULL, NULL);
388
389 memcpy(curr_dun, bc->bc_dun, sizeof(curr_dun));
390 sg_init_table(&sg, 1);
391 skcipher_request_set_crypt(ciph_req, &sg, &sg, data_unit_size,
392 iv.bytes);
393
394 /* Decrypt each segment in the bio */
395 __bio_for_each_segment(bv, bio, iter, iter) {
396 struct page *page = bv.bv_page;
397
398 if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size))
399 return BLK_STS_INVAL;
400
401 sg_set_page(&sg, page, data_unit_size, bv.bv_offset);
402
403 /* Decrypt each data unit in the segment */
404 for (i = 0; i < bv.bv_len; i += data_unit_size) {
405 blk_crypto_dun_to_iv(curr_dun, &iv);
406 if (crypto_skcipher_decrypt(ciph_req))
407 return BLK_STS_IOERR;
408 bio_crypt_dun_increment(curr_dun, 1);
409 sg.offset += data_unit_size;
410 }
411 }
412
413 return BLK_STS_OK;
414}
415
416/*
417 * The crypto API fallback's main decryption routine.
418 *
419 * Decrypts input bio in place, and calls bio_endio on the bio.
420 */
421static void blk_crypto_fallback_decrypt_bio(struct work_struct *work)
422{
423 struct bio_fallback_crypt_ctx *f_ctx =
424 container_of(work, struct bio_fallback_crypt_ctx, work);
425 struct bio *bio = f_ctx->bio;
426 struct bio_crypt_ctx *bc = &f_ctx->crypt_ctx;
427 struct blk_crypto_keyslot *slot;
428 blk_status_t status;
429
430 status = blk_crypto_get_keyslot(blk_crypto_fallback_profile,
431 bc->bc_key, &slot);
432 if (status == BLK_STS_OK) {
433 status = __blk_crypto_fallback_decrypt_bio(bio, bc,
434 f_ctx->crypt_iter,
435 blk_crypto_fallback_tfm(slot));
436 blk_crypto_put_keyslot(slot);
437 }
438 mempool_free(f_ctx, bio_fallback_crypt_ctx_pool);
439
440 bio_endio_status(bio, status);
441}
442
443/**
444 * blk_crypto_fallback_decrypt_endio - queue bio for fallback decryption
445 *
446 * @bio: the bio to queue
447 *
448 * Restore bi_private and bi_end_io, and queue the bio for decryption into a
449 * workqueue, since this function will be called from an atomic context.
450 */
451static void blk_crypto_fallback_decrypt_endio(struct bio *bio)
452{
453 struct bio_fallback_crypt_ctx *f_ctx = bio->bi_private;
454
455 bio->bi_private = f_ctx->bi_private_orig;
456 bio->bi_end_io = f_ctx->bi_end_io_orig;
457
458 /* If there was an IO error, don't queue for decrypt. */
459 if (bio->bi_status) {
460 mempool_free(f_ctx, bio_fallback_crypt_ctx_pool);
461 bio_endio(bio);
462 return;
463 }
464
465 INIT_WORK(&f_ctx->work, blk_crypto_fallback_decrypt_bio);
466 f_ctx->bio = bio;
467 queue_work(blk_crypto_wq, &f_ctx->work);
468}
469
470/**
471 * blk_crypto_fallback_bio_prep - Prepare a bio to use fallback en/decryption
472 * @bio: bio to prepare
473 *
474 * If bio is doing a WRITE operation, allocate one or more bios to contain the
475 * encrypted payload and submit them.
476 *
477 * For a READ operation, mark the bio for decryption by using bi_private and
478 * bi_end_io.
479 *
480 * In either case, this function will make the submitted bio(s) look like
481 * regular bios (i.e. as if no encryption context was ever specified) for the
482 * purposes of the rest of the stack except for blk-integrity (blk-integrity and
483 * blk-crypto are not currently supported together).
484 *
485 * Return: true if @bio should be submitted to the driver by the caller, else
486 * false. Sets bio->bi_status, calls bio_endio and returns false on error.
487 */
488bool blk_crypto_fallback_bio_prep(struct bio *bio)
489{
490 struct bio_crypt_ctx *bc = bio->bi_crypt_context;
491 struct bio_fallback_crypt_ctx *f_ctx;
492
493 if (WARN_ON_ONCE(!tfms_inited[bc->bc_key->crypto_cfg.crypto_mode])) {
494 /* User didn't call blk_crypto_start_using_key() first */
495 bio_io_error(bio);
496 return false;
497 }
498
499 if (bc->bc_key->crypto_cfg.key_type != BLK_CRYPTO_KEY_TYPE_RAW) {
500 bio_endio_status(bio, BLK_STS_NOTSUPP);
501 return false;
502 }
503
504 if (bio_data_dir(bio) == WRITE) {
505 blk_crypto_fallback_encrypt_bio(bio);
506 return false;
507 }
508
509 /*
510 * bio READ case: Set up a f_ctx in the bio's bi_private and set the
511 * bi_end_io appropriately to trigger decryption when the bio is ended.
512 */
513 f_ctx = mempool_alloc(bio_fallback_crypt_ctx_pool, GFP_NOIO);
514 f_ctx->crypt_ctx = *bc;
515 f_ctx->crypt_iter = bio->bi_iter;
516 f_ctx->bi_private_orig = bio->bi_private;
517 f_ctx->bi_end_io_orig = bio->bi_end_io;
518 bio->bi_private = (void *)f_ctx;
519 bio->bi_end_io = blk_crypto_fallback_decrypt_endio;
520 bio_crypt_free_ctx(bio);
521
522 return true;
523}
524
525int blk_crypto_fallback_evict_key(const struct blk_crypto_key *key)
526{
527 return __blk_crypto_evict_key(blk_crypto_fallback_profile, key);
528}
529
530static bool blk_crypto_fallback_inited;
531static int blk_crypto_fallback_init(void)
532{
533 int i;
534 int err;
535
536 if (blk_crypto_fallback_inited)
537 return 0;
538
539 get_random_bytes(blank_key, sizeof(blank_key));
540
541 err = bioset_init(&enc_bio_set, 64, 0, BIOSET_NEED_BVECS);
542 if (err)
543 goto out;
544
545 /* Dynamic allocation is needed because of lockdep_register_key(). */
546 blk_crypto_fallback_profile = kzalloc_obj(*blk_crypto_fallback_profile);
547 if (!blk_crypto_fallback_profile) {
548 err = -ENOMEM;
549 goto fail_free_bioset;
550 }
551
552 err = blk_crypto_profile_init(blk_crypto_fallback_profile,
553 blk_crypto_num_keyslots);
554 if (err)
555 goto fail_free_profile;
556 err = -ENOMEM;
557
558 blk_crypto_fallback_profile->ll_ops = blk_crypto_fallback_ll_ops;
559 blk_crypto_fallback_profile->max_dun_bytes_supported = BLK_CRYPTO_MAX_IV_SIZE;
560 blk_crypto_fallback_profile->key_types_supported = BLK_CRYPTO_KEY_TYPE_RAW;
561
562 /* All blk-crypto modes have a crypto API fallback. */
563 for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++)
564 blk_crypto_fallback_profile->modes_supported[i] = 0xFFFFFFFF;
565 blk_crypto_fallback_profile->modes_supported[BLK_ENCRYPTION_MODE_INVALID] = 0;
566
567 blk_crypto_wq = alloc_workqueue("blk_crypto_wq",
568 WQ_UNBOUND | WQ_HIGHPRI |
569 WQ_MEM_RECLAIM, num_online_cpus());
570 if (!blk_crypto_wq)
571 goto fail_destroy_profile;
572
573 blk_crypto_keyslots = kzalloc_objs(blk_crypto_keyslots[0],
574 blk_crypto_num_keyslots);
575 if (!blk_crypto_keyslots)
576 goto fail_free_wq;
577
578 blk_crypto_bounce_page_pool =
579 mempool_create_page_pool(num_prealloc_bounce_pg, 0);
580 if (!blk_crypto_bounce_page_pool)
581 goto fail_free_keyslots;
582
583 bio_fallback_crypt_ctx_cache = KMEM_CACHE(bio_fallback_crypt_ctx, 0);
584 if (!bio_fallback_crypt_ctx_cache)
585 goto fail_free_bounce_page_pool;
586
587 bio_fallback_crypt_ctx_pool =
588 mempool_create_slab_pool(num_prealloc_fallback_crypt_ctxs,
589 bio_fallback_crypt_ctx_cache);
590 if (!bio_fallback_crypt_ctx_pool)
591 goto fail_free_crypt_ctx_cache;
592
593 blk_crypto_fallback_inited = true;
594
595 return 0;
596fail_free_crypt_ctx_cache:
597 kmem_cache_destroy(bio_fallback_crypt_ctx_cache);
598fail_free_bounce_page_pool:
599 mempool_destroy(blk_crypto_bounce_page_pool);
600fail_free_keyslots:
601 kfree(blk_crypto_keyslots);
602fail_free_wq:
603 destroy_workqueue(blk_crypto_wq);
604fail_destroy_profile:
605 blk_crypto_profile_destroy(blk_crypto_fallback_profile);
606fail_free_profile:
607 kfree(blk_crypto_fallback_profile);
608fail_free_bioset:
609 bioset_exit(&enc_bio_set);
610out:
611 return err;
612}
613
614/*
615 * Prepare blk-crypto-fallback for the specified crypto mode.
616 * Returns -ENOPKG if the needed crypto API support is missing.
617 */
618int blk_crypto_fallback_start_using_mode(enum blk_crypto_mode_num mode_num)
619{
620 const char *cipher_str = blk_crypto_modes[mode_num].cipher_str;
621 struct blk_crypto_fallback_keyslot *slotp;
622 unsigned int i;
623 int err = 0;
624
625 /*
626 * Fast path
627 * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num]
628 * for each i are visible before we try to access them.
629 */
630 if (likely(smp_load_acquire(&tfms_inited[mode_num])))
631 return 0;
632
633 mutex_lock(&tfms_init_lock);
634 if (tfms_inited[mode_num])
635 goto out;
636
637 err = blk_crypto_fallback_init();
638 if (err)
639 goto out;
640
641 for (i = 0; i < blk_crypto_num_keyslots; i++) {
642 slotp = &blk_crypto_keyslots[i];
643 slotp->tfms[mode_num] = crypto_alloc_sync_skcipher(cipher_str,
644 0, 0);
645 if (IS_ERR(slotp->tfms[mode_num])) {
646 err = PTR_ERR(slotp->tfms[mode_num]);
647 if (err == -ENOENT) {
648 pr_warn_once("Missing crypto API support for \"%s\"\n",
649 cipher_str);
650 err = -ENOPKG;
651 }
652 slotp->tfms[mode_num] = NULL;
653 goto out_free_tfms;
654 }
655
656 crypto_sync_skcipher_set_flags(slotp->tfms[mode_num],
657 CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
658 }
659
660 /*
661 * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num]
662 * for each i are visible before we set tfms_inited[mode_num].
663 */
664 smp_store_release(&tfms_inited[mode_num], true);
665 goto out;
666
667out_free_tfms:
668 for (i = 0; i < blk_crypto_num_keyslots; i++) {
669 slotp = &blk_crypto_keyslots[i];
670 crypto_free_sync_skcipher(slotp->tfms[mode_num]);
671 slotp->tfms[mode_num] = NULL;
672 }
673out:
674 mutex_unlock(&tfms_init_lock);
675 return err;
676}