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_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 > BLK_CRYPTO_MAX_IV_SIZE)
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);