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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> | |
14 | #include <linux/keyslot-manager.h> | |
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] = { | |
488f6682 | 22 | .cipher_str = "xts(aes)", |
a892c8d5 ST |
23 | .keysize = 64, |
24 | .ivsize = 16, | |
25 | }, | |
26 | [BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = { | |
488f6682 | 27 | .cipher_str = "essiv(cbc(aes),sha256)", |
a892c8d5 ST |
28 | .keysize = 16, |
29 | .ivsize = 16, | |
30 | }, | |
31 | [BLK_ENCRYPTION_MODE_ADIANTUM] = { | |
488f6682 | 32 | .cipher_str = "adiantum(xchacha12,aes)", |
a892c8d5 ST |
33 | .keysize = 32, |
34 | .ivsize = 32, | |
35 | }, | |
36 | }; | |
37 | ||
38 | /* | |
39 | * This number needs to be at least (the number of threads doing IO | |
40 | * concurrently) * (maximum recursive depth of a bio), so that we don't | |
41 | * deadlock on crypt_ctx allocations. The default is chosen to be the same | |
42 | * as the default number of post read contexts in both EXT4 and F2FS. | |
43 | */ | |
44 | static int num_prealloc_crypt_ctxs = 128; | |
45 | ||
46 | module_param(num_prealloc_crypt_ctxs, int, 0444); | |
47 | MODULE_PARM_DESC(num_prealloc_crypt_ctxs, | |
48 | "Number of bio crypto contexts to preallocate"); | |
49 | ||
50 | static struct kmem_cache *bio_crypt_ctx_cache; | |
51 | static mempool_t *bio_crypt_ctx_pool; | |
52 | ||
53 | static int __init bio_crypt_ctx_init(void) | |
54 | { | |
55 | size_t i; | |
56 | ||
57 | bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0); | |
58 | if (!bio_crypt_ctx_cache) | |
59 | goto out_no_mem; | |
60 | ||
61 | bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs, | |
62 | bio_crypt_ctx_cache); | |
63 | if (!bio_crypt_ctx_pool) | |
64 | goto out_no_mem; | |
65 | ||
66 | /* This is assumed in various places. */ | |
67 | BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0); | |
68 | ||
69 | /* Sanity check that no algorithm exceeds the defined limits. */ | |
70 | for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) { | |
71 | BUG_ON(blk_crypto_modes[i].keysize > BLK_CRYPTO_MAX_KEY_SIZE); | |
72 | BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE); | |
73 | } | |
74 | ||
75 | return 0; | |
76 | out_no_mem: | |
77 | panic("Failed to allocate mem for bio crypt ctxs\n"); | |
78 | } | |
79 | subsys_initcall(bio_crypt_ctx_init); | |
80 | ||
81 | void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key, | |
82 | const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask) | |
83 | { | |
cf785af1 EB |
84 | struct bio_crypt_ctx *bc; |
85 | ||
86 | /* | |
87 | * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so | |
88 | * that the mempool_alloc() can't fail. | |
89 | */ | |
90 | WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM)); | |
91 | ||
92 | bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); | |
a892c8d5 ST |
93 | |
94 | bc->bc_key = key; | |
95 | memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun)); | |
96 | ||
97 | bio->bi_crypt_context = bc; | |
98 | } | |
99 | ||
100 | void __bio_crypt_free_ctx(struct bio *bio) | |
101 | { | |
102 | mempool_free(bio->bi_crypt_context, bio_crypt_ctx_pool); | |
103 | bio->bi_crypt_context = NULL; | |
104 | } | |
105 | ||
07560151 | 106 | int __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask) |
a892c8d5 ST |
107 | { |
108 | dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); | |
07560151 EB |
109 | if (!dst->bi_crypt_context) |
110 | return -ENOMEM; | |
a892c8d5 | 111 | *dst->bi_crypt_context = *src->bi_crypt_context; |
07560151 | 112 | return 0; |
a892c8d5 ST |
113 | } |
114 | EXPORT_SYMBOL_GPL(__bio_crypt_clone); | |
115 | ||
116 | /* Increments @dun by @inc, treating @dun as a multi-limb integer. */ | |
117 | void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], | |
118 | unsigned int inc) | |
119 | { | |
120 | int i; | |
121 | ||
122 | for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) { | |
123 | dun[i] += inc; | |
124 | /* | |
125 | * If the addition in this limb overflowed, then we need to | |
126 | * carry 1 into the next limb. Else the carry is 0. | |
127 | */ | |
128 | if (dun[i] < inc) | |
129 | inc = 1; | |
130 | else | |
131 | inc = 0; | |
132 | } | |
133 | } | |
134 | ||
135 | void __bio_crypt_advance(struct bio *bio, unsigned int bytes) | |
136 | { | |
137 | struct bio_crypt_ctx *bc = bio->bi_crypt_context; | |
138 | ||
139 | bio_crypt_dun_increment(bc->bc_dun, | |
140 | bytes >> bc->bc_key->data_unit_size_bits); | |
141 | } | |
142 | ||
143 | /* | |
144 | * Returns true if @bc->bc_dun plus @bytes converted to data units is equal to | |
145 | * @next_dun, treating the DUNs as multi-limb integers. | |
146 | */ | |
147 | bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc, | |
148 | unsigned int bytes, | |
149 | const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]) | |
150 | { | |
151 | int i; | |
152 | unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits; | |
153 | ||
154 | for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) { | |
155 | if (bc->bc_dun[i] + carry != next_dun[i]) | |
156 | return false; | |
157 | /* | |
158 | * If the addition in this limb overflowed, then we need to | |
159 | * carry 1 into the next limb. Else the carry is 0. | |
160 | */ | |
161 | if ((bc->bc_dun[i] + carry) < carry) | |
162 | carry = 1; | |
163 | else | |
164 | carry = 0; | |
165 | } | |
166 | ||
167 | /* If the DUN wrapped through 0, don't treat it as contiguous. */ | |
168 | return carry == 0; | |
169 | } | |
170 | ||
171 | /* | |
172 | * Checks that two bio crypt contexts are compatible - i.e. that | |
173 | * they are mergeable except for data_unit_num continuity. | |
174 | */ | |
175 | static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1, | |
176 | struct bio_crypt_ctx *bc2) | |
177 | { | |
178 | if (!bc1) | |
179 | return !bc2; | |
180 | ||
181 | return bc2 && bc1->bc_key == bc2->bc_key; | |
182 | } | |
183 | ||
184 | bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio) | |
185 | { | |
186 | return bio_crypt_ctx_compatible(rq->crypt_ctx, bio->bi_crypt_context); | |
187 | } | |
188 | ||
189 | /* | |
190 | * Checks that two bio crypt contexts are compatible, and also | |
191 | * that their data_unit_nums are continuous (and can hence be merged) | |
192 | * in the order @bc1 followed by @bc2. | |
193 | */ | |
194 | bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes, | |
195 | struct bio_crypt_ctx *bc2) | |
196 | { | |
197 | if (!bio_crypt_ctx_compatible(bc1, bc2)) | |
198 | return false; | |
199 | ||
200 | return !bc1 || bio_crypt_dun_is_contiguous(bc1, bc1_bytes, bc2->bc_dun); | |
201 | } | |
202 | ||
203 | /* Check that all I/O segments are data unit aligned. */ | |
204 | static bool bio_crypt_check_alignment(struct bio *bio) | |
205 | { | |
206 | const unsigned int data_unit_size = | |
207 | bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size; | |
208 | struct bvec_iter iter; | |
209 | struct bio_vec bv; | |
210 | ||
211 | bio_for_each_segment(bv, bio, iter) { | |
212 | if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size)) | |
213 | return false; | |
214 | } | |
215 | ||
216 | return true; | |
217 | } | |
218 | ||
219 | blk_status_t __blk_crypto_init_request(struct request *rq) | |
220 | { | |
221 | return blk_ksm_get_slot_for_key(rq->q->ksm, rq->crypt_ctx->bc_key, | |
222 | &rq->crypt_keyslot); | |
223 | } | |
224 | ||
225 | /** | |
226 | * __blk_crypto_free_request - Uninitialize the crypto fields of a request. | |
227 | * | |
228 | * @rq: The request whose crypto fields to uninitialize. | |
229 | * | |
230 | * Completely uninitializes the crypto fields of a request. If a keyslot has | |
231 | * been programmed into some inline encryption hardware, that keyslot is | |
232 | * released. The rq->crypt_ctx is also freed. | |
233 | */ | |
234 | void __blk_crypto_free_request(struct request *rq) | |
235 | { | |
236 | blk_ksm_put_slot(rq->crypt_keyslot); | |
237 | mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool); | |
238 | blk_crypto_rq_set_defaults(rq); | |
239 | } | |
240 | ||
241 | /** | |
242 | * __blk_crypto_bio_prep - Prepare bio for inline encryption | |
243 | * | |
244 | * @bio_ptr: pointer to original bio pointer | |
245 | * | |
488f6682 ST |
246 | * If the bio crypt context provided for the bio is supported by the underlying |
247 | * device's inline encryption hardware, do nothing. | |
248 | * | |
249 | * Otherwise, try to perform en/decryption for this bio by falling back to the | |
250 | * kernel crypto API. When the crypto API fallback is used for encryption, | |
251 | * blk-crypto may choose to split the bio into 2 - the first one that will | |
252 | * continue to be processed and the second one that will be resubmitted via | |
ed00aabd | 253 | * submit_bio_noacct. A bounce bio will be allocated to encrypt the contents |
488f6682 ST |
254 | * of the aforementioned "first one", and *bio_ptr will be updated to this |
255 | * bounce bio. | |
a892c8d5 ST |
256 | * |
257 | * Caller must ensure bio has bio_crypt_ctx. | |
258 | * | |
259 | * Return: true on success; false on error (and bio->bi_status will be set | |
260 | * appropriately, and bio_endio() will have been called so bio | |
261 | * submission should abort). | |
262 | */ | |
263 | bool __blk_crypto_bio_prep(struct bio **bio_ptr) | |
264 | { | |
265 | struct bio *bio = *bio_ptr; | |
266 | const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key; | |
a892c8d5 ST |
267 | |
268 | /* Error if bio has no data. */ | |
488f6682 ST |
269 | if (WARN_ON_ONCE(!bio_has_data(bio))) { |
270 | bio->bi_status = BLK_STS_IOERR; | |
a892c8d5 | 271 | goto fail; |
488f6682 | 272 | } |
a892c8d5 | 273 | |
488f6682 ST |
274 | if (!bio_crypt_check_alignment(bio)) { |
275 | bio->bi_status = BLK_STS_IOERR; | |
a892c8d5 | 276 | goto fail; |
488f6682 | 277 | } |
a892c8d5 ST |
278 | |
279 | /* | |
488f6682 ST |
280 | * Success if device supports the encryption context, or if we succeeded |
281 | * in falling back to the crypto API. | |
a892c8d5 | 282 | */ |
309dca30 | 283 | if (blk_ksm_crypto_cfg_supported(bio->bi_bdev->bd_disk->queue->ksm, |
488f6682 ST |
284 | &bc_key->crypto_cfg)) |
285 | return true; | |
a892c8d5 | 286 | |
488f6682 ST |
287 | if (blk_crypto_fallback_bio_prep(bio_ptr)) |
288 | return true; | |
a892c8d5 | 289 | fail: |
a892c8d5 ST |
290 | bio_endio(*bio_ptr); |
291 | return false; | |
292 | } | |
293 | ||
93f221ae EB |
294 | int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, |
295 | gfp_t gfp_mask) | |
a892c8d5 | 296 | { |
93f221ae | 297 | if (!rq->crypt_ctx) { |
a892c8d5 | 298 | rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); |
93f221ae EB |
299 | if (!rq->crypt_ctx) |
300 | return -ENOMEM; | |
301 | } | |
a892c8d5 | 302 | *rq->crypt_ctx = *bio->bi_crypt_context; |
93f221ae | 303 | return 0; |
a892c8d5 ST |
304 | } |
305 | ||
306 | /** | |
307 | * blk_crypto_init_key() - Prepare a key for use with blk-crypto | |
308 | * @blk_key: Pointer to the blk_crypto_key to initialize. | |
309 | * @raw_key: Pointer to the raw key. Must be the correct length for the chosen | |
310 | * @crypto_mode; see blk_crypto_modes[]. | |
311 | * @crypto_mode: identifier for the encryption algorithm to use | |
312 | * @dun_bytes: number of bytes that will be used to specify the DUN when this | |
313 | * key is used | |
314 | * @data_unit_size: the data unit size to use for en/decryption | |
315 | * | |
316 | * Return: 0 on success, -errno on failure. The caller is responsible for | |
317 | * zeroizing both blk_key and raw_key when done with them. | |
318 | */ | |
319 | int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key, | |
320 | enum blk_crypto_mode_num crypto_mode, | |
321 | unsigned int dun_bytes, | |
322 | unsigned int data_unit_size) | |
323 | { | |
324 | const struct blk_crypto_mode *mode; | |
325 | ||
326 | memset(blk_key, 0, sizeof(*blk_key)); | |
327 | ||
328 | if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes)) | |
329 | return -EINVAL; | |
330 | ||
331 | mode = &blk_crypto_modes[crypto_mode]; | |
332 | if (mode->keysize == 0) | |
333 | return -EINVAL; | |
334 | ||
335 | if (dun_bytes == 0 || dun_bytes > BLK_CRYPTO_MAX_IV_SIZE) | |
336 | return -EINVAL; | |
337 | ||
338 | if (!is_power_of_2(data_unit_size)) | |
339 | return -EINVAL; | |
340 | ||
341 | blk_key->crypto_cfg.crypto_mode = crypto_mode; | |
342 | blk_key->crypto_cfg.dun_bytes = dun_bytes; | |
343 | blk_key->crypto_cfg.data_unit_size = data_unit_size; | |
344 | blk_key->data_unit_size_bits = ilog2(data_unit_size); | |
345 | blk_key->size = mode->keysize; | |
346 | memcpy(blk_key->raw, raw_key, mode->keysize); | |
347 | ||
348 | return 0; | |
349 | } | |
350 | ||
488f6682 ST |
351 | /* |
352 | * Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the | |
353 | * request queue it's submitted to supports inline crypto, or the | |
354 | * blk-crypto-fallback is enabled and supports the cfg). | |
355 | */ | |
a892c8d5 ST |
356 | bool blk_crypto_config_supported(struct request_queue *q, |
357 | const struct blk_crypto_config *cfg) | |
358 | { | |
488f6682 ST |
359 | return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) || |
360 | blk_ksm_crypto_cfg_supported(q->ksm, cfg); | |
a892c8d5 ST |
361 | } |
362 | ||
363 | /** | |
364 | * blk_crypto_start_using_key() - Start using a blk_crypto_key on a device | |
365 | * @key: A key to use on the device | |
366 | * @q: the request queue for the device | |
367 | * | |
488f6682 ST |
368 | * Upper layers must call this function to ensure that either the hardware |
369 | * supports the key's crypto settings, or the crypto API fallback has transforms | |
370 | * for the needed mode allocated and ready to go. This function may allocate | |
371 | * an skcipher, and *should not* be called from the data path, since that might | |
372 | * cause a deadlock | |
a892c8d5 | 373 | * |
488f6682 ST |
374 | * Return: 0 on success; -ENOPKG if the hardware doesn't support the key and |
375 | * blk-crypto-fallback is either disabled or the needed algorithm | |
376 | * is disabled in the crypto API; or another -errno code. | |
a892c8d5 ST |
377 | */ |
378 | int blk_crypto_start_using_key(const struct blk_crypto_key *key, | |
379 | struct request_queue *q) | |
380 | { | |
381 | if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg)) | |
382 | return 0; | |
488f6682 | 383 | return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode); |
a892c8d5 ST |
384 | } |
385 | ||
386 | /** | |
387 | * blk_crypto_evict_key() - Evict a key from any inline encryption hardware | |
388 | * it may have been programmed into | |
389 | * @q: The request queue who's associated inline encryption hardware this key | |
390 | * might have been programmed into | |
391 | * @key: The key to evict | |
392 | * | |
393 | * Upper layers (filesystems) must call this function to ensure that a key is | |
394 | * evicted from any hardware that it might have been programmed into. The key | |
395 | * must not be in use by any in-flight IO when this function is called. | |
396 | * | |
397 | * Return: 0 on success or if key is not present in the q's ksm, -err on error. | |
398 | */ | |
399 | int blk_crypto_evict_key(struct request_queue *q, | |
400 | const struct blk_crypto_key *key) | |
401 | { | |
402 | if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg)) | |
403 | return blk_ksm_evict_key(q->ksm, key); | |
404 | ||
488f6682 ST |
405 | /* |
406 | * If the request queue's associated inline encryption hardware didn't | |
407 | * have support for the key, then the key might have been programmed | |
408 | * into the fallback keyslot manager, so try to evict from there. | |
409 | */ | |
410 | return blk_crypto_fallback_evict_key(key); | |
a892c8d5 | 411 | } |
9355a9eb | 412 | EXPORT_SYMBOL_GPL(blk_crypto_evict_key); |