1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright 2019 Google LLC
7 * Refer to Documentation/block/inline-encryption.rst for detailed explanation.
10 #define pr_fmt(fmt) "blk-crypto: " fmt
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>
18 #include "blk-crypto-internal.h"
20 const struct blk_crypto_mode blk_crypto_modes
[] = {
21 [BLK_ENCRYPTION_MODE_AES_256_XTS
] = {
22 .cipher_str
= "xts(aes)",
26 [BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV
] = {
27 .cipher_str
= "essiv(cbc(aes),sha256)",
31 [BLK_ENCRYPTION_MODE_ADIANTUM
] = {
32 .cipher_str
= "adiantum(xchacha12,aes)",
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.
44 static int num_prealloc_crypt_ctxs
= 128;
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");
50 static struct kmem_cache
*bio_crypt_ctx_cache
;
51 static mempool_t
*bio_crypt_ctx_pool
;
53 static int __init
bio_crypt_ctx_init(void)
57 bio_crypt_ctx_cache
= KMEM_CACHE(bio_crypt_ctx
, 0);
58 if (!bio_crypt_ctx_cache
)
61 bio_crypt_ctx_pool
= mempool_create_slab_pool(num_prealloc_crypt_ctxs
,
63 if (!bio_crypt_ctx_pool
)
66 /* This is assumed in various places. */
67 BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID
!= 0);
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
);
77 panic("Failed to allocate mem for bio crypt ctxs\n");
79 subsys_initcall(bio_crypt_ctx_init
);
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
)
84 struct bio_crypt_ctx
*bc
;
87 * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so
88 * that the mempool_alloc() can't fail.
90 WARN_ON_ONCE(!(gfp_mask
& __GFP_DIRECT_RECLAIM
));
92 bc
= mempool_alloc(bio_crypt_ctx_pool
, gfp_mask
);
95 memcpy(bc
->bc_dun
, dun
, sizeof(bc
->bc_dun
));
97 bio
->bi_crypt_context
= bc
;
100 void __bio_crypt_free_ctx(struct bio
*bio
)
102 mempool_free(bio
->bi_crypt_context
, bio_crypt_ctx_pool
);
103 bio
->bi_crypt_context
= NULL
;
106 int __bio_crypt_clone(struct bio
*dst
, struct bio
*src
, gfp_t gfp_mask
)
108 dst
->bi_crypt_context
= mempool_alloc(bio_crypt_ctx_pool
, gfp_mask
);
109 if (!dst
->bi_crypt_context
)
111 *dst
->bi_crypt_context
= *src
->bi_crypt_context
;
114 EXPORT_SYMBOL_GPL(__bio_crypt_clone
);
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
],
122 for (i
= 0; inc
&& i
< BLK_CRYPTO_DUN_ARRAY_SIZE
; i
++) {
125 * If the addition in this limb overflowed, then we need to
126 * carry 1 into the next limb. Else the carry is 0.
135 void __bio_crypt_advance(struct bio
*bio
, unsigned int bytes
)
137 struct bio_crypt_ctx
*bc
= bio
->bi_crypt_context
;
139 bio_crypt_dun_increment(bc
->bc_dun
,
140 bytes
>> bc
->bc_key
->data_unit_size_bits
);
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.
147 bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx
*bc
,
149 const u64 next_dun
[BLK_CRYPTO_DUN_ARRAY_SIZE
])
152 unsigned int carry
= bytes
>> bc
->bc_key
->data_unit_size_bits
;
154 for (i
= 0; i
< BLK_CRYPTO_DUN_ARRAY_SIZE
; i
++) {
155 if (bc
->bc_dun
[i
] + carry
!= next_dun
[i
])
158 * If the addition in this limb overflowed, then we need to
159 * carry 1 into the next limb. Else the carry is 0.
161 if ((bc
->bc_dun
[i
] + carry
) < carry
)
167 /* If the DUN wrapped through 0, don't treat it as contiguous. */
172 * Checks that two bio crypt contexts are compatible - i.e. that
173 * they are mergeable except for data_unit_num continuity.
175 static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx
*bc1
,
176 struct bio_crypt_ctx
*bc2
)
181 return bc2
&& bc1
->bc_key
== bc2
->bc_key
;
184 bool bio_crypt_rq_ctx_compatible(struct request
*rq
, struct bio
*bio
)
186 return bio_crypt_ctx_compatible(rq
->crypt_ctx
, bio
->bi_crypt_context
);
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.
194 bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx
*bc1
, unsigned int bc1_bytes
,
195 struct bio_crypt_ctx
*bc2
)
197 if (!bio_crypt_ctx_compatible(bc1
, bc2
))
200 return !bc1
|| bio_crypt_dun_is_contiguous(bc1
, bc1_bytes
, bc2
->bc_dun
);
203 /* Check that all I/O segments are data unit aligned. */
204 static bool bio_crypt_check_alignment(struct bio
*bio
)
206 const unsigned int data_unit_size
=
207 bio
->bi_crypt_context
->bc_key
->crypto_cfg
.data_unit_size
;
208 struct bvec_iter iter
;
211 bio_for_each_segment(bv
, bio
, iter
) {
212 if (!IS_ALIGNED(bv
.bv_len
| bv
.bv_offset
, data_unit_size
))
219 blk_status_t
__blk_crypto_init_request(struct request
*rq
)
221 return blk_ksm_get_slot_for_key(rq
->q
->ksm
, rq
->crypt_ctx
->bc_key
,
226 * __blk_crypto_free_request - Uninitialize the crypto fields of a request.
228 * @rq: The request whose crypto fields to uninitialize.
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.
234 void __blk_crypto_free_request(struct request
*rq
)
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
);
242 * __blk_crypto_bio_prep - Prepare bio for inline encryption
244 * @bio_ptr: pointer to original bio pointer
246 * If the bio crypt context provided for the bio is supported by the underlying
247 * device's inline encryption hardware, do nothing.
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
253 * submit_bio_noacct. A bounce bio will be allocated to encrypt the contents
254 * of the aforementioned "first one", and *bio_ptr will be updated to this
257 * Caller must ensure bio has bio_crypt_ctx.
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).
263 bool __blk_crypto_bio_prep(struct bio
**bio_ptr
)
265 struct bio
*bio
= *bio_ptr
;
266 const struct blk_crypto_key
*bc_key
= bio
->bi_crypt_context
->bc_key
;
268 /* Error if bio has no data. */
269 if (WARN_ON_ONCE(!bio_has_data(bio
))) {
270 bio
->bi_status
= BLK_STS_IOERR
;
274 if (!bio_crypt_check_alignment(bio
)) {
275 bio
->bi_status
= BLK_STS_IOERR
;
280 * Success if device supports the encryption context, or if we succeeded
281 * in falling back to the crypto API.
283 if (blk_ksm_crypto_cfg_supported(bio
->bi_bdev
->bd_disk
->queue
->ksm
,
284 &bc_key
->crypto_cfg
))
287 if (blk_crypto_fallback_bio_prep(bio_ptr
))
294 int __blk_crypto_rq_bio_prep(struct request
*rq
, struct bio
*bio
,
297 if (!rq
->crypt_ctx
) {
298 rq
->crypt_ctx
= mempool_alloc(bio_crypt_ctx_pool
, gfp_mask
);
302 *rq
->crypt_ctx
= *bio
->bi_crypt_context
;
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
314 * @data_unit_size: the data unit size to use for en/decryption
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.
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
)
324 const struct blk_crypto_mode
*mode
;
326 memset(blk_key
, 0, sizeof(*blk_key
));
328 if (crypto_mode
>= ARRAY_SIZE(blk_crypto_modes
))
331 mode
= &blk_crypto_modes
[crypto_mode
];
332 if (mode
->keysize
== 0)
335 if (dun_bytes
== 0 || dun_bytes
> mode
->ivsize
)
338 if (!is_power_of_2(data_unit_size
))
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
);
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).
356 bool blk_crypto_config_supported(struct request_queue
*q
,
357 const struct blk_crypto_config
*cfg
)
359 return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK
) ||
360 blk_ksm_crypto_cfg_supported(q
->ksm
, cfg
);
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
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
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.
378 int blk_crypto_start_using_key(const struct blk_crypto_key
*key
,
379 struct request_queue
*q
)
381 if (blk_ksm_crypto_cfg_supported(q
->ksm
, &key
->crypto_cfg
))
383 return blk_crypto_fallback_start_using_mode(key
->crypto_cfg
.crypto_mode
);
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
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.
397 * Return: 0 on success or if key is not present in the q's ksm, -err on error.
399 int blk_crypto_evict_key(struct request_queue
*q
,
400 const struct blk_crypto_key
*key
)
402 if (blk_ksm_crypto_cfg_supported(q
->ksm
, &key
->crypto_cfg
))
403 return blk_ksm_evict_key(q
->ksm
, key
);
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.
410 return blk_crypto_fallback_evict_key(key
);
412 EXPORT_SYMBOL_GPL(blk_crypto_evict_key
);