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