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/ratelimit.h>
17 #include <linux/slab.h>
19 #include "blk-crypto-internal.h"
21 const struct blk_crypto_mode blk_crypto_modes[] = {
22 [BLK_ENCRYPTION_MODE_AES_256_XTS] = {
23 .cipher_str = "xts(aes)",
27 [BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = {
28 .cipher_str = "essiv(cbc(aes),sha256)",
32 [BLK_ENCRYPTION_MODE_ADIANTUM] = {
33 .cipher_str = "adiantum(xchacha12,aes)",
40 * This number needs to be at least (the number of threads doing IO
41 * concurrently) * (maximum recursive depth of a bio), so that we don't
42 * deadlock on crypt_ctx allocations. The default is chosen to be the same
43 * as the default number of post read contexts in both EXT4 and F2FS.
45 static int num_prealloc_crypt_ctxs = 128;
47 module_param(num_prealloc_crypt_ctxs, int, 0444);
48 MODULE_PARM_DESC(num_prealloc_crypt_ctxs,
49 "Number of bio crypto contexts to preallocate");
51 static struct kmem_cache *bio_crypt_ctx_cache;
52 static mempool_t *bio_crypt_ctx_pool;
54 static int __init bio_crypt_ctx_init(void)
58 bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0);
59 if (!bio_crypt_ctx_cache)
62 bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs,
64 if (!bio_crypt_ctx_pool)
67 /* This is assumed in various places. */
68 BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0);
70 /* Sanity check that no algorithm exceeds the defined limits. */
71 for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) {
72 BUG_ON(blk_crypto_modes[i].keysize > BLK_CRYPTO_MAX_KEY_SIZE);
73 BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE);
78 panic("Failed to allocate mem for bio crypt ctxs\n");
80 subsys_initcall(bio_crypt_ctx_init);
82 void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key,
83 const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask)
85 struct bio_crypt_ctx *bc;
88 * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so
89 * that the mempool_alloc() can't fail.
91 WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM));
93 bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
96 memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun));
98 bio->bi_crypt_context = bc;
101 void __bio_crypt_free_ctx(struct bio *bio)
103 mempool_free(bio->bi_crypt_context, bio_crypt_ctx_pool);
104 bio->bi_crypt_context = NULL;
107 int __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask)
109 dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
110 if (!dst->bi_crypt_context)
112 *dst->bi_crypt_context = *src->bi_crypt_context;
115 EXPORT_SYMBOL_GPL(__bio_crypt_clone);
117 /* Increments @dun by @inc, treating @dun as a multi-limb integer. */
118 void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
123 for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
126 * If the addition in this limb overflowed, then we need to
127 * carry 1 into the next limb. Else the carry is 0.
136 void __bio_crypt_advance(struct bio *bio, unsigned int bytes)
138 struct bio_crypt_ctx *bc = bio->bi_crypt_context;
140 bio_crypt_dun_increment(bc->bc_dun,
141 bytes >> bc->bc_key->data_unit_size_bits);
145 * Returns true if @bc->bc_dun plus @bytes converted to data units is equal to
146 * @next_dun, treating the DUNs as multi-limb integers.
148 bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc,
150 const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE])
153 unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits;
155 for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
156 if (bc->bc_dun[i] + carry != next_dun[i])
159 * If the addition in this limb overflowed, then we need to
160 * carry 1 into the next limb. Else the carry is 0.
162 if ((bc->bc_dun[i] + carry) < carry)
168 /* If the DUN wrapped through 0, don't treat it as contiguous. */
173 * Checks that two bio crypt contexts are compatible - i.e. that
174 * they are mergeable except for data_unit_num continuity.
176 static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1,
177 struct bio_crypt_ctx *bc2)
182 return bc2 && bc1->bc_key == bc2->bc_key;
185 bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio)
187 return bio_crypt_ctx_compatible(rq->crypt_ctx, bio->bi_crypt_context);
191 * Checks that two bio crypt contexts are compatible, and also
192 * that their data_unit_nums are continuous (and can hence be merged)
193 * in the order @bc1 followed by @bc2.
195 bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes,
196 struct bio_crypt_ctx *bc2)
198 if (!bio_crypt_ctx_compatible(bc1, bc2))
201 return !bc1 || bio_crypt_dun_is_contiguous(bc1, bc1_bytes, bc2->bc_dun);
204 /* Check that all I/O segments are data unit aligned. */
205 static bool bio_crypt_check_alignment(struct bio *bio)
207 const unsigned int data_unit_size =
208 bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size;
209 struct bvec_iter iter;
212 bio_for_each_segment(bv, bio, iter) {
213 if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size))
220 blk_status_t __blk_crypto_rq_get_keyslot(struct request *rq)
222 return blk_ksm_get_slot_for_key(rq->q->ksm, rq->crypt_ctx->bc_key,
226 void __blk_crypto_rq_put_keyslot(struct request *rq)
228 blk_ksm_put_slot(rq->crypt_keyslot);
229 rq->crypt_keyslot = NULL;
232 void __blk_crypto_free_request(struct request *rq)
234 /* The keyslot, if one was needed, should have been released earlier. */
235 if (WARN_ON_ONCE(rq->crypt_keyslot))
236 __blk_crypto_rq_put_keyslot(rq);
238 mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool);
239 rq->crypt_ctx = NULL;
243 * __blk_crypto_bio_prep - Prepare bio for inline encryption
245 * @bio_ptr: pointer to original bio pointer
247 * If the bio crypt context provided for the bio is supported by the underlying
248 * device's inline encryption hardware, do nothing.
250 * Otherwise, try to perform en/decryption for this bio by falling back to the
251 * kernel crypto API. When the crypto API fallback is used for encryption,
252 * blk-crypto may choose to split the bio into 2 - the first one that will
253 * continue to be processed and the second one that will be resubmitted via
254 * submit_bio_noacct. A bounce bio will be allocated to encrypt the contents
255 * of the aforementioned "first one", and *bio_ptr will be updated to this
258 * Caller must ensure bio has bio_crypt_ctx.
260 * Return: true on success; false on error (and bio->bi_status will be set
261 * appropriately, and bio_endio() will have been called so bio
262 * submission should abort).
264 bool __blk_crypto_bio_prep(struct bio **bio_ptr)
266 struct bio *bio = *bio_ptr;
267 const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key;
269 /* Error if bio has no data. */
270 if (WARN_ON_ONCE(!bio_has_data(bio))) {
271 bio->bi_status = BLK_STS_IOERR;
275 if (!bio_crypt_check_alignment(bio)) {
276 bio->bi_status = BLK_STS_IOERR;
281 * Success if device supports the encryption context, or if we succeeded
282 * in falling back to the crypto API.
284 if (blk_ksm_crypto_cfg_supported(bio->bi_disk->queue->ksm,
285 &bc_key->crypto_cfg))
288 if (blk_crypto_fallback_bio_prep(bio_ptr))
295 int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio,
298 if (!rq->crypt_ctx) {
299 rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
303 *rq->crypt_ctx = *bio->bi_crypt_context;
308 * blk_crypto_init_key() - Prepare a key for use with blk-crypto
309 * @blk_key: Pointer to the blk_crypto_key to initialize.
310 * @raw_key: Pointer to the raw key. Must be the correct length for the chosen
311 * @crypto_mode; see blk_crypto_modes[].
312 * @crypto_mode: identifier for the encryption algorithm to use
313 * @dun_bytes: number of bytes that will be used to specify the DUN when this
315 * @data_unit_size: the data unit size to use for en/decryption
317 * Return: 0 on success, -errno on failure. The caller is responsible for
318 * zeroizing both blk_key and raw_key when done with them.
320 int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key,
321 enum blk_crypto_mode_num crypto_mode,
322 unsigned int dun_bytes,
323 unsigned int data_unit_size)
325 const struct blk_crypto_mode *mode;
327 memset(blk_key, 0, sizeof(*blk_key));
329 if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes))
332 mode = &blk_crypto_modes[crypto_mode];
333 if (mode->keysize == 0)
336 if (dun_bytes == 0 || dun_bytes > mode->ivsize)
339 if (!is_power_of_2(data_unit_size))
342 blk_key->crypto_cfg.crypto_mode = crypto_mode;
343 blk_key->crypto_cfg.dun_bytes = dun_bytes;
344 blk_key->crypto_cfg.data_unit_size = data_unit_size;
345 blk_key->data_unit_size_bits = ilog2(data_unit_size);
346 blk_key->size = mode->keysize;
347 memcpy(blk_key->raw, raw_key, mode->keysize);
353 * Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the
354 * request queue it's submitted to supports inline crypto, or the
355 * blk-crypto-fallback is enabled and supports the cfg).
357 bool blk_crypto_config_supported(struct request_queue *q,
358 const struct blk_crypto_config *cfg)
360 return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) ||
361 blk_ksm_crypto_cfg_supported(q->ksm, cfg);
365 * blk_crypto_start_using_key() - Start using a blk_crypto_key on a device
366 * @key: A key to use on the device
367 * @q: the request queue for the device
369 * Upper layers must call this function to ensure that either the hardware
370 * supports the key's crypto settings, or the crypto API fallback has transforms
371 * for the needed mode allocated and ready to go. This function may allocate
372 * an skcipher, and *should not* be called from the data path, since that might
375 * Return: 0 on success; -ENOPKG if the hardware doesn't support the key and
376 * blk-crypto-fallback is either disabled or the needed algorithm
377 * is disabled in the crypto API; or another -errno code.
379 int blk_crypto_start_using_key(const struct blk_crypto_key *key,
380 struct request_queue *q)
382 if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg))
384 return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode);
388 * blk_crypto_evict_key() - Evict a blk_crypto_key from a request_queue
389 * @q: a request_queue on which I/O using the key may have been done
390 * @key: the key to evict
392 * For a given request_queue, this function removes the given blk_crypto_key
393 * from the keyslot management structures and evicts it from any underlying
394 * hardware keyslot(s) or blk-crypto-fallback keyslot it may have been
397 * Upper layers must call this before freeing the blk_crypto_key. It must be
398 * called for every request_queue the key may have been used on. The key must
399 * no longer be in use by any I/O when this function is called.
401 * Context: May sleep.
403 void blk_crypto_evict_key(struct request_queue *q,
404 const struct blk_crypto_key *key)
408 if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg))
409 err = blk_ksm_evict_key(q->ksm, key);
411 err = blk_crypto_fallback_evict_key(key);
413 * An error can only occur here if the key failed to be evicted from a
414 * keyslot (due to a hardware or driver issue) or is allegedly still in
415 * use by I/O (due to a kernel bug). Even in these cases, the key is
416 * still unlinked from the keyslot management structures, and the caller
417 * is allowed and expected to free it right away. There's nothing
418 * callers can do to handle errors, so just log them and return void.
421 pr_warn_ratelimited("error %d evicting key\n", err);