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: " fmt
11
12#include <linux/bio.h>
13#include <linux/blkdev.h>
14#include <linux/blk-crypto-profile.h>
15#include <linux/module.h>
16#include <linux/ratelimit.h>
17#include <linux/slab.h>
18
19#include "blk-crypto-internal.h"
20
21const struct blk_crypto_mode blk_crypto_modes[] = {
22 [BLK_ENCRYPTION_MODE_AES_256_XTS] = {
23 .name = "AES-256-XTS",
24 .cipher_str = "xts(aes)",
25 .keysize = 64,
26 .security_strength = 32,
27 .ivsize = 16,
28 },
29 [BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = {
30 .name = "AES-128-CBC-ESSIV",
31 .cipher_str = "essiv(cbc(aes),sha256)",
32 .keysize = 16,
33 .security_strength = 16,
34 .ivsize = 16,
35 },
36 [BLK_ENCRYPTION_MODE_ADIANTUM] = {
37 .name = "Adiantum",
38 .cipher_str = "adiantum(xchacha12,aes)",
39 .keysize = 32,
40 .security_strength = 32,
41 .ivsize = 32,
42 },
43 [BLK_ENCRYPTION_MODE_SM4_XTS] = {
44 .name = "SM4-XTS",
45 .cipher_str = "xts(sm4)",
46 .keysize = 32,
47 .security_strength = 16,
48 .ivsize = 16,
49 },
50};
51
52/*
53 * This number needs to be at least (the number of threads doing IO
54 * concurrently) * (maximum recursive depth of a bio), so that we don't
55 * deadlock on crypt_ctx allocations. The default is chosen to be the same
56 * as the default number of post read contexts in both EXT4 and F2FS.
57 */
58static int num_prealloc_crypt_ctxs = 128;
59
60module_param(num_prealloc_crypt_ctxs, int, 0444);
61MODULE_PARM_DESC(num_prealloc_crypt_ctxs,
62 "Number of bio crypto contexts to preallocate");
63
64static struct kmem_cache *bio_crypt_ctx_cache;
65static mempool_t *bio_crypt_ctx_pool;
66
67static int __init bio_crypt_ctx_init(void)
68{
69 size_t i;
70
71 bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0);
72 if (!bio_crypt_ctx_cache)
73 goto out_no_mem;
74
75 bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs,
76 bio_crypt_ctx_cache);
77 if (!bio_crypt_ctx_pool)
78 goto out_no_mem;
79
80 /* This is assumed in various places. */
81 BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0);
82
83 /*
84 * Validate the crypto mode properties. This ideally would be done with
85 * static assertions, but boot-time checks are the next best thing.
86 */
87 for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) {
88 BUG_ON(blk_crypto_modes[i].keysize >
89 BLK_CRYPTO_MAX_RAW_KEY_SIZE);
90 BUG_ON(blk_crypto_modes[i].security_strength >
91 blk_crypto_modes[i].keysize);
92 BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE);
93 }
94
95 return 0;
96out_no_mem:
97 panic(fmt: "Failed to allocate mem for bio crypt ctxs\n");
98}
99subsys_initcall(bio_crypt_ctx_init);
100
101void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key,
102 const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask)
103{
104 struct bio_crypt_ctx *bc;
105
106 /*
107 * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so
108 * that the mempool_alloc() can't fail.
109 */
110 WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM));
111
112 bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
113
114 bc->bc_key = key;
115 memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun));
116
117 bio->bi_crypt_context = bc;
118}
119
120void __bio_crypt_free_ctx(struct bio *bio)
121{
122 mempool_free(element: bio->bi_crypt_context, pool: bio_crypt_ctx_pool);
123 bio->bi_crypt_context = NULL;
124}
125
126int __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask)
127{
128 dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
129 if (!dst->bi_crypt_context)
130 return -ENOMEM;
131 *dst->bi_crypt_context = *src->bi_crypt_context;
132 return 0;
133}
134
135/* Increments @dun by @inc, treating @dun as a multi-limb integer. */
136void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
137 unsigned int inc)
138{
139 int i;
140
141 for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
142 dun[i] += inc;
143 /*
144 * If the addition in this limb overflowed, then we need to
145 * carry 1 into the next limb. Else the carry is 0.
146 */
147 if (dun[i] < inc)
148 inc = 1;
149 else
150 inc = 0;
151 }
152}
153
154void __bio_crypt_advance(struct bio *bio, unsigned int bytes)
155{
156 struct bio_crypt_ctx *bc = bio->bi_crypt_context;
157
158 bio_crypt_dun_increment(dun: bc->bc_dun,
159 inc: bytes >> bc->bc_key->data_unit_size_bits);
160}
161
162/*
163 * Returns true if @bc->bc_dun plus @bytes converted to data units is equal to
164 * @next_dun, treating the DUNs as multi-limb integers.
165 */
166bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc,
167 unsigned int bytes,
168 const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE])
169{
170 int i;
171 unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits;
172
173 for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
174 if (bc->bc_dun[i] + carry != next_dun[i])
175 return false;
176 /*
177 * If the addition in this limb overflowed, then we need to
178 * carry 1 into the next limb. Else the carry is 0.
179 */
180 if ((bc->bc_dun[i] + carry) < carry)
181 carry = 1;
182 else
183 carry = 0;
184 }
185
186 /* If the DUN wrapped through 0, don't treat it as contiguous. */
187 return carry == 0;
188}
189
190/*
191 * Checks that two bio crypt contexts are compatible - i.e. that
192 * they are mergeable except for data_unit_num continuity.
193 */
194static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1,
195 struct bio_crypt_ctx *bc2)
196{
197 if (!bc1)
198 return !bc2;
199
200 return bc2 && bc1->bc_key == bc2->bc_key;
201}
202
203bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio)
204{
205 return bio_crypt_ctx_compatible(bc1: rq->crypt_ctx, bc2: bio->bi_crypt_context);
206}
207
208/*
209 * Checks that two bio crypt contexts are compatible, and also
210 * that their data_unit_nums are continuous (and can hence be merged)
211 * in the order @bc1 followed by @bc2.
212 */
213bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes,
214 struct bio_crypt_ctx *bc2)
215{
216 if (!bio_crypt_ctx_compatible(bc1, bc2))
217 return false;
218
219 return !bc1 || bio_crypt_dun_is_contiguous(bc: bc1, bytes: bc1_bytes, next_dun: bc2->bc_dun);
220}
221
222/* Check that all I/O segments are data unit aligned. */
223static bool bio_crypt_check_alignment(struct bio *bio)
224{
225 const unsigned int data_unit_size =
226 bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size;
227 struct bvec_iter iter;
228 struct bio_vec bv;
229
230 bio_for_each_segment(bv, bio, iter) {
231 if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size))
232 return false;
233 }
234
235 return true;
236}
237
238blk_status_t __blk_crypto_rq_get_keyslot(struct request *rq)
239{
240 return blk_crypto_get_keyslot(profile: rq->q->crypto_profile,
241 key: rq->crypt_ctx->bc_key,
242 slot_ptr: &rq->crypt_keyslot);
243}
244
245void __blk_crypto_rq_put_keyslot(struct request *rq)
246{
247 blk_crypto_put_keyslot(slot: rq->crypt_keyslot);
248 rq->crypt_keyslot = NULL;
249}
250
251void __blk_crypto_free_request(struct request *rq)
252{
253 /* The keyslot, if one was needed, should have been released earlier. */
254 if (WARN_ON_ONCE(rq->crypt_keyslot))
255 __blk_crypto_rq_put_keyslot(rq);
256
257 mempool_free(element: rq->crypt_ctx, pool: bio_crypt_ctx_pool);
258 rq->crypt_ctx = NULL;
259}
260
261/**
262 * __blk_crypto_bio_prep - Prepare bio for inline encryption
263 *
264 * @bio_ptr: pointer to original bio pointer
265 *
266 * If the bio crypt context provided for the bio is supported by the underlying
267 * device's inline encryption hardware, do nothing.
268 *
269 * Otherwise, try to perform en/decryption for this bio by falling back to the
270 * kernel crypto API. When the crypto API fallback is used for encryption,
271 * blk-crypto may choose to split the bio into 2 - the first one that will
272 * continue to be processed and the second one that will be resubmitted via
273 * submit_bio_noacct. A bounce bio will be allocated to encrypt the contents
274 * of the aforementioned "first one", and *bio_ptr will be updated to this
275 * bounce bio.
276 *
277 * Caller must ensure bio has bio_crypt_ctx.
278 *
279 * Return: true on success; false on error (and bio->bi_status will be set
280 * appropriately, and bio_endio() will have been called so bio
281 * submission should abort).
282 */
283bool __blk_crypto_bio_prep(struct bio **bio_ptr)
284{
285 struct bio *bio = *bio_ptr;
286 const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key;
287
288 /* Error if bio has no data. */
289 if (WARN_ON_ONCE(!bio_has_data(bio))) {
290 bio->bi_status = BLK_STS_IOERR;
291 goto fail;
292 }
293
294 if (!bio_crypt_check_alignment(bio)) {
295 bio->bi_status = BLK_STS_INVAL;
296 goto fail;
297 }
298
299 /*
300 * Success if device supports the encryption context, or if we succeeded
301 * in falling back to the crypto API.
302 */
303 if (blk_crypto_config_supported_natively(bdev: bio->bi_bdev,
304 cfg: &bc_key->crypto_cfg))
305 return true;
306 if (blk_crypto_fallback_bio_prep(bio_ptr))
307 return true;
308fail:
309 bio_endio(*bio_ptr);
310 return false;
311}
312
313int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio,
314 gfp_t gfp_mask)
315{
316 if (!rq->crypt_ctx) {
317 rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
318 if (!rq->crypt_ctx)
319 return -ENOMEM;
320 }
321 *rq->crypt_ctx = *bio->bi_crypt_context;
322 return 0;
323}
324
325/**
326 * blk_crypto_init_key() - Prepare a key for use with blk-crypto
327 * @blk_key: Pointer to the blk_crypto_key to initialize.
328 * @key_bytes: the bytes of the key
329 * @key_size: size of the key in bytes
330 * @key_type: type of the key -- either raw or hardware-wrapped
331 * @crypto_mode: identifier for the encryption algorithm to use
332 * @dun_bytes: number of bytes that will be used to specify the DUN when this
333 * key is used
334 * @data_unit_size: the data unit size to use for en/decryption
335 *
336 * Return: 0 on success, -errno on failure. The caller is responsible for
337 * zeroizing both blk_key and key_bytes when done with them.
338 */
339int blk_crypto_init_key(struct blk_crypto_key *blk_key,
340 const u8 *key_bytes, size_t key_size,
341 enum blk_crypto_key_type key_type,
342 enum blk_crypto_mode_num crypto_mode,
343 unsigned int dun_bytes,
344 unsigned int data_unit_size)
345{
346 const struct blk_crypto_mode *mode;
347
348 memset(blk_key, 0, sizeof(*blk_key));
349
350 if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes))
351 return -EINVAL;
352
353 mode = &blk_crypto_modes[crypto_mode];
354 switch (key_type) {
355 case BLK_CRYPTO_KEY_TYPE_RAW:
356 if (key_size != mode->keysize)
357 return -EINVAL;
358 break;
359 case BLK_CRYPTO_KEY_TYPE_HW_WRAPPED:
360 if (key_size < mode->security_strength ||
361 key_size > BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE)
362 return -EINVAL;
363 break;
364 default:
365 return -EINVAL;
366 }
367
368 if (dun_bytes == 0 || dun_bytes > mode->ivsize)
369 return -EINVAL;
370
371 if (!is_power_of_2(n: data_unit_size))
372 return -EINVAL;
373
374 blk_key->crypto_cfg.crypto_mode = crypto_mode;
375 blk_key->crypto_cfg.dun_bytes = dun_bytes;
376 blk_key->crypto_cfg.data_unit_size = data_unit_size;
377 blk_key->crypto_cfg.key_type = key_type;
378 blk_key->data_unit_size_bits = ilog2(data_unit_size);
379 blk_key->size = key_size;
380 memcpy(blk_key->bytes, key_bytes, key_size);
381
382 return 0;
383}
384
385bool blk_crypto_config_supported_natively(struct block_device *bdev,
386 const struct blk_crypto_config *cfg)
387{
388 return __blk_crypto_cfg_supported(profile: bdev_get_queue(bdev)->crypto_profile,
389 cfg);
390}
391
392/*
393 * Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the
394 * block_device it's submitted to supports inline crypto, or the
395 * blk-crypto-fallback is enabled and supports the cfg).
396 */
397bool blk_crypto_config_supported(struct block_device *bdev,
398 const struct blk_crypto_config *cfg)
399{
400 if (IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) &&
401 cfg->key_type == BLK_CRYPTO_KEY_TYPE_RAW)
402 return true;
403 return blk_crypto_config_supported_natively(bdev, cfg);
404}
405
406/**
407 * blk_crypto_start_using_key() - Start using a blk_crypto_key on a device
408 * @bdev: block device to operate on
409 * @key: A key to use on the device
410 *
411 * Upper layers must call this function to ensure that either the hardware
412 * supports the key's crypto settings, or the crypto API fallback has transforms
413 * for the needed mode allocated and ready to go. This function may allocate
414 * an skcipher, and *should not* be called from the data path, since that might
415 * cause a deadlock
416 *
417 * Return: 0 on success; -EOPNOTSUPP if the key is wrapped but the hardware does
418 * not support wrapped keys; -ENOPKG if the key is a raw key but the
419 * hardware does not support raw keys and blk-crypto-fallback is either
420 * disabled or the needed algorithm is disabled in the crypto API; or
421 * another -errno code if something else went wrong.
422 */
423int blk_crypto_start_using_key(struct block_device *bdev,
424 const struct blk_crypto_key *key)
425{
426 if (blk_crypto_config_supported_natively(bdev, cfg: &key->crypto_cfg))
427 return 0;
428 if (key->crypto_cfg.key_type != BLK_CRYPTO_KEY_TYPE_RAW) {
429 pr_warn_ratelimited("%pg: no support for wrapped keys\n", bdev);
430 return -EOPNOTSUPP;
431 }
432 return blk_crypto_fallback_start_using_mode(mode_num: key->crypto_cfg.crypto_mode);
433}
434
435/**
436 * blk_crypto_evict_key() - Evict a blk_crypto_key from a block_device
437 * @bdev: a block_device on which I/O using the key may have been done
438 * @key: the key to evict
439 *
440 * For a given block_device, this function removes the given blk_crypto_key from
441 * the keyslot management structures and evicts it from any underlying hardware
442 * keyslot(s) or blk-crypto-fallback keyslot it may have been programmed into.
443 *
444 * Upper layers must call this before freeing the blk_crypto_key. It must be
445 * called for every block_device the key may have been used on. The key must no
446 * longer be in use by any I/O when this function is called.
447 *
448 * Context: May sleep.
449 */
450void blk_crypto_evict_key(struct block_device *bdev,
451 const struct blk_crypto_key *key)
452{
453 struct request_queue *q = bdev_get_queue(bdev);
454 int err;
455
456 if (blk_crypto_config_supported_natively(bdev, cfg: &key->crypto_cfg))
457 err = __blk_crypto_evict_key(profile: q->crypto_profile, key);
458 else
459 err = blk_crypto_fallback_evict_key(key);
460 /*
461 * An error can only occur here if the key failed to be evicted from a
462 * keyslot (due to a hardware or driver issue) or is allegedly still in
463 * use by I/O (due to a kernel bug). Even in these cases, the key is
464 * still unlinked from the keyslot management structures, and the caller
465 * is allowed and expected to free it right away. There's nothing
466 * callers can do to handle errors, so just log them and return void.
467 */
468 if (err)
469 pr_warn_ratelimited("%pg: error %d evicting key\n", bdev, err);
470}
471EXPORT_SYMBOL_GPL(blk_crypto_evict_key);
472
473static int blk_crypto_ioctl_import_key(struct blk_crypto_profile *profile,
474 void __user *argp)
475{
476 struct blk_crypto_import_key_arg arg;
477 u8 raw_key[BLK_CRYPTO_MAX_RAW_KEY_SIZE];
478 u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE];
479 int ret;
480
481 if (copy_from_user(to: &arg, from: argp, n: sizeof(arg)))
482 return -EFAULT;
483
484 if (memchr_inv(p: arg.reserved, c: 0, size: sizeof(arg.reserved)))
485 return -EINVAL;
486
487 if (arg.raw_key_size < 16 || arg.raw_key_size > sizeof(raw_key))
488 return -EINVAL;
489
490 if (copy_from_user(to: raw_key, u64_to_user_ptr(arg.raw_key_ptr),
491 n: arg.raw_key_size)) {
492 ret = -EFAULT;
493 goto out;
494 }
495 ret = blk_crypto_import_key(profile, raw_key, raw_key_size: arg.raw_key_size, lt_key);
496 if (ret < 0)
497 goto out;
498 if (ret > arg.lt_key_size) {
499 ret = -EOVERFLOW;
500 goto out;
501 }
502 arg.lt_key_size = ret;
503 if (copy_to_user(u64_to_user_ptr(arg.lt_key_ptr), from: lt_key,
504 n: arg.lt_key_size) ||
505 copy_to_user(to: argp, from: &arg, n: sizeof(arg))) {
506 ret = -EFAULT;
507 goto out;
508 }
509 ret = 0;
510
511out:
512 memzero_explicit(s: raw_key, count: sizeof(raw_key));
513 memzero_explicit(s: lt_key, count: sizeof(lt_key));
514 return ret;
515}
516
517static int blk_crypto_ioctl_generate_key(struct blk_crypto_profile *profile,
518 void __user *argp)
519{
520 struct blk_crypto_generate_key_arg arg;
521 u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE];
522 int ret;
523
524 if (copy_from_user(to: &arg, from: argp, n: sizeof(arg)))
525 return -EFAULT;
526
527 if (memchr_inv(p: arg.reserved, c: 0, size: sizeof(arg.reserved)))
528 return -EINVAL;
529
530 ret = blk_crypto_generate_key(profile, lt_key);
531 if (ret < 0)
532 goto out;
533 if (ret > arg.lt_key_size) {
534 ret = -EOVERFLOW;
535 goto out;
536 }
537 arg.lt_key_size = ret;
538 if (copy_to_user(u64_to_user_ptr(arg.lt_key_ptr), from: lt_key,
539 n: arg.lt_key_size) ||
540 copy_to_user(to: argp, from: &arg, n: sizeof(arg))) {
541 ret = -EFAULT;
542 goto out;
543 }
544 ret = 0;
545
546out:
547 memzero_explicit(s: lt_key, count: sizeof(lt_key));
548 return ret;
549}
550
551static int blk_crypto_ioctl_prepare_key(struct blk_crypto_profile *profile,
552 void __user *argp)
553{
554 struct blk_crypto_prepare_key_arg arg;
555 u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE];
556 u8 eph_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE];
557 int ret;
558
559 if (copy_from_user(to: &arg, from: argp, n: sizeof(arg)))
560 return -EFAULT;
561
562 if (memchr_inv(p: arg.reserved, c: 0, size: sizeof(arg.reserved)))
563 return -EINVAL;
564
565 if (arg.lt_key_size > sizeof(lt_key))
566 return -EINVAL;
567
568 if (copy_from_user(to: lt_key, u64_to_user_ptr(arg.lt_key_ptr),
569 n: arg.lt_key_size)) {
570 ret = -EFAULT;
571 goto out;
572 }
573 ret = blk_crypto_prepare_key(profile, lt_key, lt_key_size: arg.lt_key_size, eph_key);
574 if (ret < 0)
575 goto out;
576 if (ret > arg.eph_key_size) {
577 ret = -EOVERFLOW;
578 goto out;
579 }
580 arg.eph_key_size = ret;
581 if (copy_to_user(u64_to_user_ptr(arg.eph_key_ptr), from: eph_key,
582 n: arg.eph_key_size) ||
583 copy_to_user(to: argp, from: &arg, n: sizeof(arg))) {
584 ret = -EFAULT;
585 goto out;
586 }
587 ret = 0;
588
589out:
590 memzero_explicit(s: lt_key, count: sizeof(lt_key));
591 memzero_explicit(s: eph_key, count: sizeof(eph_key));
592 return ret;
593}
594
595int blk_crypto_ioctl(struct block_device *bdev, unsigned int cmd,
596 void __user *argp)
597{
598 struct blk_crypto_profile *profile =
599 bdev_get_queue(bdev)->crypto_profile;
600
601 if (!profile)
602 return -EOPNOTSUPP;
603
604 switch (cmd) {
605 case BLKCRYPTOIMPORTKEY:
606 return blk_crypto_ioctl_import_key(profile, argp);
607 case BLKCRYPTOGENERATEKEY:
608 return blk_crypto_ioctl_generate_key(profile, argp);
609 case BLKCRYPTOPREPAREKEY:
610 return blk_crypto_ioctl_prepare_key(profile, argp);
611 default:
612 return -ENOTTY;
613 }
614}
615

source code of linux/block/blk-crypto.c