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a892c8d5 ST |
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> | |
1e8d44bd | 14 | #include <linux/blk-crypto-profile.h> |
a892c8d5 ST |
15 | #include <linux/module.h> |
16 | #include <linux/slab.h> | |
17 | ||
18 | #include "blk-crypto-internal.h" | |
19 | ||
20 | const struct blk_crypto_mode blk_crypto_modes[] = { | |
21 | [BLK_ENCRYPTION_MODE_AES_256_XTS] = { | |
20f01f16 | 22 | .name = "AES-256-XTS", |
488f6682 | 23 | .cipher_str = "xts(aes)", |
a892c8d5 ST |
24 | .keysize = 64, |
25 | .ivsize = 16, | |
26 | }, | |
27 | [BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = { | |
20f01f16 | 28 | .name = "AES-128-CBC-ESSIV", |
488f6682 | 29 | .cipher_str = "essiv(cbc(aes),sha256)", |
a892c8d5 ST |
30 | .keysize = 16, |
31 | .ivsize = 16, | |
32 | }, | |
33 | [BLK_ENCRYPTION_MODE_ADIANTUM] = { | |
20f01f16 | 34 | .name = "Adiantum", |
488f6682 | 35 | .cipher_str = "adiantum(xchacha12,aes)", |
a892c8d5 ST |
36 | .keysize = 32, |
37 | .ivsize = 32, | |
38 | }, | |
39 | }; | |
40 | ||
41 | /* | |
42 | * This number needs to be at least (the number of threads doing IO | |
43 | * concurrently) * (maximum recursive depth of a bio), so that we don't | |
44 | * deadlock on crypt_ctx allocations. The default is chosen to be the same | |
45 | * as the default number of post read contexts in both EXT4 and F2FS. | |
46 | */ | |
47 | static int num_prealloc_crypt_ctxs = 128; | |
48 | ||
49 | module_param(num_prealloc_crypt_ctxs, int, 0444); | |
50 | MODULE_PARM_DESC(num_prealloc_crypt_ctxs, | |
51 | "Number of bio crypto contexts to preallocate"); | |
52 | ||
53 | static struct kmem_cache *bio_crypt_ctx_cache; | |
54 | static mempool_t *bio_crypt_ctx_pool; | |
55 | ||
56 | static int __init bio_crypt_ctx_init(void) | |
57 | { | |
58 | size_t i; | |
59 | ||
60 | bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0); | |
61 | if (!bio_crypt_ctx_cache) | |
62 | goto out_no_mem; | |
63 | ||
64 | bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs, | |
65 | bio_crypt_ctx_cache); | |
66 | if (!bio_crypt_ctx_pool) | |
67 | goto out_no_mem; | |
68 | ||
69 | /* This is assumed in various places. */ | |
70 | BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0); | |
71 | ||
72 | /* Sanity check that no algorithm exceeds the defined limits. */ | |
73 | for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) { | |
74 | BUG_ON(blk_crypto_modes[i].keysize > BLK_CRYPTO_MAX_KEY_SIZE); | |
75 | BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE); | |
76 | } | |
77 | ||
78 | return 0; | |
79 | out_no_mem: | |
80 | panic("Failed to allocate mem for bio crypt ctxs\n"); | |
81 | } | |
82 | subsys_initcall(bio_crypt_ctx_init); | |
83 | ||
84 | void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key, | |
85 | const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask) | |
86 | { | |
cf785af1 EB |
87 | struct bio_crypt_ctx *bc; |
88 | ||
89 | /* | |
90 | * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so | |
91 | * that the mempool_alloc() can't fail. | |
92 | */ | |
93 | WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM)); | |
94 | ||
95 | bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); | |
a892c8d5 ST |
96 | |
97 | bc->bc_key = key; | |
98 | memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun)); | |
99 | ||
100 | bio->bi_crypt_context = bc; | |
101 | } | |
102 | ||
103 | void __bio_crypt_free_ctx(struct bio *bio) | |
104 | { | |
105 | mempool_free(bio->bi_crypt_context, bio_crypt_ctx_pool); | |
106 | bio->bi_crypt_context = NULL; | |
107 | } | |
108 | ||
07560151 | 109 | int __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask) |
a892c8d5 ST |
110 | { |
111 | dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); | |
07560151 EB |
112 | if (!dst->bi_crypt_context) |
113 | return -ENOMEM; | |
a892c8d5 | 114 | *dst->bi_crypt_context = *src->bi_crypt_context; |
07560151 | 115 | return 0; |
a892c8d5 | 116 | } |
a892c8d5 ST |
117 | |
118 | /* Increments @dun by @inc, treating @dun as a multi-limb integer. */ | |
119 | void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], | |
120 | unsigned int inc) | |
121 | { | |
122 | int i; | |
123 | ||
124 | for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) { | |
125 | dun[i] += inc; | |
126 | /* | |
127 | * If the addition in this limb overflowed, then we need to | |
128 | * carry 1 into the next limb. Else the carry is 0. | |
129 | */ | |
130 | if (dun[i] < inc) | |
131 | inc = 1; | |
132 | else | |
133 | inc = 0; | |
134 | } | |
135 | } | |
136 | ||
137 | void __bio_crypt_advance(struct bio *bio, unsigned int bytes) | |
138 | { | |
139 | struct bio_crypt_ctx *bc = bio->bi_crypt_context; | |
140 | ||
141 | bio_crypt_dun_increment(bc->bc_dun, | |
142 | bytes >> bc->bc_key->data_unit_size_bits); | |
143 | } | |
144 | ||
145 | /* | |
146 | * Returns true if @bc->bc_dun plus @bytes converted to data units is equal to | |
147 | * @next_dun, treating the DUNs as multi-limb integers. | |
148 | */ | |
149 | bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc, | |
150 | unsigned int bytes, | |
151 | const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]) | |
152 | { | |
153 | int i; | |
154 | unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits; | |
155 | ||
156 | for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) { | |
157 | if (bc->bc_dun[i] + carry != next_dun[i]) | |
158 | return false; | |
159 | /* | |
160 | * If the addition in this limb overflowed, then we need to | |
161 | * carry 1 into the next limb. Else the carry is 0. | |
162 | */ | |
163 | if ((bc->bc_dun[i] + carry) < carry) | |
164 | carry = 1; | |
165 | else | |
166 | carry = 0; | |
167 | } | |
168 | ||
169 | /* If the DUN wrapped through 0, don't treat it as contiguous. */ | |
170 | return carry == 0; | |
171 | } | |
172 | ||
173 | /* | |
174 | * Checks that two bio crypt contexts are compatible - i.e. that | |
175 | * they are mergeable except for data_unit_num continuity. | |
176 | */ | |
177 | static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1, | |
178 | struct bio_crypt_ctx *bc2) | |
179 | { | |
180 | if (!bc1) | |
181 | return !bc2; | |
182 | ||
183 | return bc2 && bc1->bc_key == bc2->bc_key; | |
184 | } | |
185 | ||
186 | bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio) | |
187 | { | |
188 | return bio_crypt_ctx_compatible(rq->crypt_ctx, bio->bi_crypt_context); | |
189 | } | |
190 | ||
191 | /* | |
192 | * Checks that two bio crypt contexts are compatible, and also | |
193 | * that their data_unit_nums are continuous (and can hence be merged) | |
194 | * in the order @bc1 followed by @bc2. | |
195 | */ | |
196 | bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes, | |
197 | struct bio_crypt_ctx *bc2) | |
198 | { | |
199 | if (!bio_crypt_ctx_compatible(bc1, bc2)) | |
200 | return false; | |
201 | ||
202 | return !bc1 || bio_crypt_dun_is_contiguous(bc1, bc1_bytes, bc2->bc_dun); | |
203 | } | |
204 | ||
205 | /* Check that all I/O segments are data unit aligned. */ | |
206 | static bool bio_crypt_check_alignment(struct bio *bio) | |
207 | { | |
208 | const unsigned int data_unit_size = | |
209 | bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size; | |
210 | struct bvec_iter iter; | |
211 | struct bio_vec bv; | |
212 | ||
213 | bio_for_each_segment(bv, bio, iter) { | |
214 | if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size)) | |
215 | return false; | |
216 | } | |
217 | ||
218 | return true; | |
219 | } | |
220 | ||
221 | blk_status_t __blk_crypto_init_request(struct request *rq) | |
222 | { | |
cb77cb5a EB |
223 | return blk_crypto_get_keyslot(rq->q->crypto_profile, |
224 | rq->crypt_ctx->bc_key, | |
225 | &rq->crypt_keyslot); | |
a892c8d5 ST |
226 | } |
227 | ||
228 | /** | |
229 | * __blk_crypto_free_request - Uninitialize the crypto fields of a request. | |
230 | * | |
231 | * @rq: The request whose crypto fields to uninitialize. | |
232 | * | |
233 | * Completely uninitializes the crypto fields of a request. If a keyslot has | |
234 | * been programmed into some inline encryption hardware, that keyslot is | |
235 | * released. The rq->crypt_ctx is also freed. | |
236 | */ | |
237 | void __blk_crypto_free_request(struct request *rq) | |
238 | { | |
cb77cb5a | 239 | blk_crypto_put_keyslot(rq->crypt_keyslot); |
a892c8d5 ST |
240 | mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool); |
241 | blk_crypto_rq_set_defaults(rq); | |
242 | } | |
243 | ||
244 | /** | |
245 | * __blk_crypto_bio_prep - Prepare bio for inline encryption | |
246 | * | |
247 | * @bio_ptr: pointer to original bio pointer | |
248 | * | |
488f6682 ST |
249 | * If the bio crypt context provided for the bio is supported by the underlying |
250 | * device's inline encryption hardware, do nothing. | |
251 | * | |
252 | * Otherwise, try to perform en/decryption for this bio by falling back to the | |
253 | * kernel crypto API. When the crypto API fallback is used for encryption, | |
254 | * blk-crypto may choose to split the bio into 2 - the first one that will | |
255 | * continue to be processed and the second one that will be resubmitted via | |
ed00aabd | 256 | * submit_bio_noacct. A bounce bio will be allocated to encrypt the contents |
488f6682 ST |
257 | * of the aforementioned "first one", and *bio_ptr will be updated to this |
258 | * bounce bio. | |
a892c8d5 ST |
259 | * |
260 | * Caller must ensure bio has bio_crypt_ctx. | |
261 | * | |
262 | * Return: true on success; false on error (and bio->bi_status will be set | |
263 | * appropriately, and bio_endio() will have been called so bio | |
264 | * submission should abort). | |
265 | */ | |
266 | bool __blk_crypto_bio_prep(struct bio **bio_ptr) | |
267 | { | |
268 | struct bio *bio = *bio_ptr; | |
269 | const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key; | |
cb77cb5a | 270 | struct blk_crypto_profile *profile; |
a892c8d5 ST |
271 | |
272 | /* Error if bio has no data. */ | |
488f6682 ST |
273 | if (WARN_ON_ONCE(!bio_has_data(bio))) { |
274 | bio->bi_status = BLK_STS_IOERR; | |
a892c8d5 | 275 | goto fail; |
488f6682 | 276 | } |
a892c8d5 | 277 | |
488f6682 ST |
278 | if (!bio_crypt_check_alignment(bio)) { |
279 | bio->bi_status = BLK_STS_IOERR; | |
a892c8d5 | 280 | goto fail; |
488f6682 | 281 | } |
a892c8d5 ST |
282 | |
283 | /* | |
488f6682 ST |
284 | * Success if device supports the encryption context, or if we succeeded |
285 | * in falling back to the crypto API. | |
a892c8d5 | 286 | */ |
cb77cb5a EB |
287 | profile = bdev_get_queue(bio->bi_bdev)->crypto_profile; |
288 | if (__blk_crypto_cfg_supported(profile, &bc_key->crypto_cfg)) | |
488f6682 | 289 | return true; |
a892c8d5 | 290 | |
488f6682 ST |
291 | if (blk_crypto_fallback_bio_prep(bio_ptr)) |
292 | return true; | |
a892c8d5 | 293 | fail: |
a892c8d5 ST |
294 | bio_endio(*bio_ptr); |
295 | return false; | |
296 | } | |
297 | ||
93f221ae EB |
298 | int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, |
299 | gfp_t gfp_mask) | |
a892c8d5 | 300 | { |
93f221ae | 301 | if (!rq->crypt_ctx) { |
a892c8d5 | 302 | rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); |
93f221ae EB |
303 | if (!rq->crypt_ctx) |
304 | return -ENOMEM; | |
305 | } | |
a892c8d5 | 306 | *rq->crypt_ctx = *bio->bi_crypt_context; |
93f221ae | 307 | return 0; |
a892c8d5 ST |
308 | } |
309 | ||
310 | /** | |
311 | * blk_crypto_init_key() - Prepare a key for use with blk-crypto | |
312 | * @blk_key: Pointer to the blk_crypto_key to initialize. | |
313 | * @raw_key: Pointer to the raw key. Must be the correct length for the chosen | |
314 | * @crypto_mode; see blk_crypto_modes[]. | |
315 | * @crypto_mode: identifier for the encryption algorithm to use | |
316 | * @dun_bytes: number of bytes that will be used to specify the DUN when this | |
317 | * key is used | |
318 | * @data_unit_size: the data unit size to use for en/decryption | |
319 | * | |
320 | * Return: 0 on success, -errno on failure. The caller is responsible for | |
321 | * zeroizing both blk_key and raw_key when done with them. | |
322 | */ | |
323 | int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key, | |
324 | enum blk_crypto_mode_num crypto_mode, | |
325 | unsigned int dun_bytes, | |
326 | unsigned int data_unit_size) | |
327 | { | |
328 | const struct blk_crypto_mode *mode; | |
329 | ||
330 | memset(blk_key, 0, sizeof(*blk_key)); | |
331 | ||
332 | if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes)) | |
333 | return -EINVAL; | |
334 | ||
335 | mode = &blk_crypto_modes[crypto_mode]; | |
336 | if (mode->keysize == 0) | |
337 | return -EINVAL; | |
338 | ||
cc40b722 | 339 | if (dun_bytes == 0 || dun_bytes > mode->ivsize) |
a892c8d5 ST |
340 | return -EINVAL; |
341 | ||
342 | if (!is_power_of_2(data_unit_size)) | |
343 | return -EINVAL; | |
344 | ||
345 | blk_key->crypto_cfg.crypto_mode = crypto_mode; | |
346 | blk_key->crypto_cfg.dun_bytes = dun_bytes; | |
347 | blk_key->crypto_cfg.data_unit_size = data_unit_size; | |
348 | blk_key->data_unit_size_bits = ilog2(data_unit_size); | |
349 | blk_key->size = mode->keysize; | |
350 | memcpy(blk_key->raw, raw_key, mode->keysize); | |
351 | ||
352 | return 0; | |
353 | } | |
354 | ||
488f6682 ST |
355 | /* |
356 | * Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the | |
357 | * request queue it's submitted to supports inline crypto, or the | |
358 | * blk-crypto-fallback is enabled and supports the cfg). | |
359 | */ | |
a892c8d5 ST |
360 | bool blk_crypto_config_supported(struct request_queue *q, |
361 | const struct blk_crypto_config *cfg) | |
362 | { | |
488f6682 | 363 | return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) || |
cb77cb5a | 364 | __blk_crypto_cfg_supported(q->crypto_profile, cfg); |
a892c8d5 ST |
365 | } |
366 | ||
367 | /** | |
368 | * blk_crypto_start_using_key() - Start using a blk_crypto_key on a device | |
369 | * @key: A key to use on the device | |
370 | * @q: the request queue for the device | |
371 | * | |
488f6682 ST |
372 | * Upper layers must call this function to ensure that either the hardware |
373 | * supports the key's crypto settings, or the crypto API fallback has transforms | |
374 | * for the needed mode allocated and ready to go. This function may allocate | |
375 | * an skcipher, and *should not* be called from the data path, since that might | |
376 | * cause a deadlock | |
a892c8d5 | 377 | * |
488f6682 ST |
378 | * Return: 0 on success; -ENOPKG if the hardware doesn't support the key and |
379 | * blk-crypto-fallback is either disabled or the needed algorithm | |
380 | * is disabled in the crypto API; or another -errno code. | |
a892c8d5 ST |
381 | */ |
382 | int blk_crypto_start_using_key(const struct blk_crypto_key *key, | |
383 | struct request_queue *q) | |
384 | { | |
cb77cb5a | 385 | if (__blk_crypto_cfg_supported(q->crypto_profile, &key->crypto_cfg)) |
a892c8d5 | 386 | return 0; |
488f6682 | 387 | return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode); |
a892c8d5 ST |
388 | } |
389 | ||
390 | /** | |
391 | * blk_crypto_evict_key() - Evict a key from any inline encryption hardware | |
392 | * it may have been programmed into | |
393 | * @q: The request queue who's associated inline encryption hardware this key | |
394 | * might have been programmed into | |
395 | * @key: The key to evict | |
396 | * | |
397 | * Upper layers (filesystems) must call this function to ensure that a key is | |
398 | * evicted from any hardware that it might have been programmed into. The key | |
399 | * must not be in use by any in-flight IO when this function is called. | |
400 | * | |
cb77cb5a | 401 | * Return: 0 on success or if the key wasn't in any keyslot; -errno on error. |
a892c8d5 ST |
402 | */ |
403 | int blk_crypto_evict_key(struct request_queue *q, | |
404 | const struct blk_crypto_key *key) | |
405 | { | |
cb77cb5a EB |
406 | if (__blk_crypto_cfg_supported(q->crypto_profile, &key->crypto_cfg)) |
407 | return __blk_crypto_evict_key(q->crypto_profile, key); | |
a892c8d5 | 408 | |
488f6682 | 409 | /* |
cb77cb5a EB |
410 | * If the request_queue didn't support the key, then blk-crypto-fallback |
411 | * may have been used, so try to evict the key from blk-crypto-fallback. | |
488f6682 ST |
412 | */ |
413 | return blk_crypto_fallback_evict_key(key); | |
a892c8d5 | 414 | } |
9355a9eb | 415 | EXPORT_SYMBOL_GPL(blk_crypto_evict_key); |