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