block/blk-crypto.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright 2019 Google LLC
  */

 /*
  * Refer to Documentation/block/inline-encryption.rst for detailed explanation.
  */

 #define pr_fmt(fmt) "blk-crypto: " fmt

 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <linux/blk-crypto-profile.h>
 #include <linux/module.h>
 #include <linux/slab.h>

 #include "blk-crypto-internal.h"

 const struct blk_crypto_mode blk_crypto_modes[] = {
 	[BLK_ENCRYPTION_MODE_AES_256_XTS] = {
 		.name = "AES-256-XTS",
 		.cipher_str = "xts(aes)",
 		.keysize = 64,
 		.ivsize = 16,
 	},
 	[BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = {
 		.name = "AES-128-CBC-ESSIV",
 		.cipher_str = "essiv(cbc(aes),sha256)",
 		.keysize = 16,
 		.ivsize = 16,
 	},
 	[BLK_ENCRYPTION_MODE_ADIANTUM] = {
 		.name = "Adiantum",
 		.cipher_str = "adiantum(xchacha12,aes)",
 		.keysize = 32,
 		.ivsize = 32,
 	},
 };

 /*
  * This number needs to be at least (the number of threads doing IO
  * concurrently) * (maximum recursive depth of a bio), so that we don't
  * deadlock on crypt_ctx allocations. The default is chosen to be the same
  * as the default number of post read contexts in both EXT4 and F2FS.
  */
 static int num_prealloc_crypt_ctxs = 128;

 module_param(num_prealloc_crypt_ctxs, int, 0444);
 MODULE_PARM_DESC(num_prealloc_crypt_ctxs,
 		"Number of bio crypto contexts to preallocate");

 static struct kmem_cache *bio_crypt_ctx_cache;
 static mempool_t *bio_crypt_ctx_pool;

 static int __init bio_crypt_ctx_init(void)
 {
 	size_t i;

 	bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0);
 	if (!bio_crypt_ctx_cache)
 		goto out_no_mem;

 	bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs,
 						      bio_crypt_ctx_cache);
 	if (!bio_crypt_ctx_pool)
 		goto out_no_mem;

 	/* This is assumed in various places. */
 	BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0);

 	/* Sanity check that no algorithm exceeds the defined limits. */
 	for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) {
 		BUG_ON(blk_crypto_modes[i].keysize > BLK_CRYPTO_MAX_KEY_SIZE);
 		BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE);
 	}

 	return 0;
 out_no_mem:
 	panic("Failed to allocate mem for bio crypt ctxs\n");
 }
 subsys_initcall(bio_crypt_ctx_init);

 void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key,
 		       const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask)
 {
 	struct bio_crypt_ctx *bc;

 	/*
 	 * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so
 	 * that the mempool_alloc() can't fail.
 	 */
 	WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM));

 	bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);

 	bc->bc_key = key;
 	memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun));

 	bio->bi_crypt_context = bc;
 }

 void __bio_crypt_free_ctx(struct bio *bio)
 {
 	mempool_free(bio->bi_crypt_context, bio_crypt_ctx_pool);
 	bio->bi_crypt_context = NULL;
 }

 int __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask)
 {
 	dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
 	if (!dst->bi_crypt_context)
 		return -ENOMEM;
 	*dst->bi_crypt_context = *src->bi_crypt_context;
 	return 0;
 }

 /* Increments @dun by @inc, treating @dun as a multi-limb integer. */
 void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
 			     unsigned int inc)
 {
 	int i;

 	for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
 		dun[i] += inc;
 		/*
 		 * If the addition in this limb overflowed, then we need to
 		 * carry 1 into the next limb. Else the carry is 0.
 		 */
 		if (dun[i] < inc)
 			inc = 1;
 		else
 			inc = 0;
 	}
 }

 void __bio_crypt_advance(struct bio *bio, unsigned int bytes)
 {
 	struct bio_crypt_ctx *bc = bio->bi_crypt_context;

 	bio_crypt_dun_increment(bc->bc_dun,
 				bytes >> bc->bc_key->data_unit_size_bits);
 }

 /*
  * Returns true if @bc->bc_dun plus @bytes converted to data units is equal to
  * @next_dun, treating the DUNs as multi-limb integers.
  */
 bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc,
 				 unsigned int bytes,
 				 const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE])
 {
 	int i;
 	unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits;

 	for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
 		if (bc->bc_dun[i] + carry != next_dun[i])
 			return false;
 		/*
 		 * If the addition in this limb overflowed, then we need to
 		 * carry 1 into the next limb. Else the carry is 0.
 		 */
 		if ((bc->bc_dun[i] + carry) < carry)
 			carry = 1;
 		else
 			carry = 0;
 	}

 	/* If the DUN wrapped through 0, don't treat it as contiguous. */
 	return carry == 0;
 }

 /*
  * Checks that two bio crypt contexts are compatible - i.e. that
  * they are mergeable except for data_unit_num continuity.
  */
 static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1,
 				     struct bio_crypt_ctx *bc2)
 {
 	if (!bc1)
 		return !bc2;

 	return bc2 && bc1->bc_key == bc2->bc_key;
 }

 bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio)
 {
 	return bio_crypt_ctx_compatible(rq->crypt_ctx, bio->bi_crypt_context);
 }

 /*
  * Checks that two bio crypt contexts are compatible, and also
  * that their data_unit_nums are continuous (and can hence be merged)
  * in the order @bc1 followed by @bc2.
  */
 bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes,
 			     struct bio_crypt_ctx *bc2)
 {
 	if (!bio_crypt_ctx_compatible(bc1, bc2))
 		return false;

 	return !bc1 || bio_crypt_dun_is_contiguous(bc1, bc1_bytes, bc2->bc_dun);
 }

 /* Check that all I/O segments are data unit aligned. */
 static bool bio_crypt_check_alignment(struct bio *bio)
 {
 	const unsigned int data_unit_size =
 		bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size;
 	struct bvec_iter iter;
 	struct bio_vec bv;

 	bio_for_each_segment(bv, bio, iter) {
 		if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size))
 			return false;
 	}

 	return true;
 }

 blk_status_t __blk_crypto_init_request(struct request *rq)
 {
 	return blk_crypto_get_keyslot(rq->q->crypto_profile,
 				      rq->crypt_ctx->bc_key,
 				      &rq->crypt_keyslot);
 }

 /**
  * __blk_crypto_free_request - Uninitialize the crypto fields of a request.
  *
  * @rq: The request whose crypto fields to uninitialize.
  *
  * Completely uninitializes the crypto fields of a request. If a keyslot has
  * been programmed into some inline encryption hardware, that keyslot is
  * released. The rq->crypt_ctx is also freed.
  */
 void __blk_crypto_free_request(struct request *rq)
 {
 	blk_crypto_put_keyslot(rq->crypt_keyslot);
 	mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool);
 	blk_crypto_rq_set_defaults(rq);
 }

 /**
  * __blk_crypto_bio_prep - Prepare bio for inline encryption
  *
  * @bio_ptr: pointer to original bio pointer
  *
  * If the bio crypt context provided for the bio is supported by the underlying
  * device's inline encryption hardware, do nothing.
  *
  * Otherwise, try to perform en/decryption for this bio by falling back to the
  * kernel crypto API. When the crypto API fallback is used for encryption,
  * blk-crypto may choose to split the bio into 2 - the first one that will
  * continue to be processed and the second one that will be resubmitted via
  * submit_bio_noacct. A bounce bio will be allocated to encrypt the contents
  * of the aforementioned "first one", and *bio_ptr will be updated to this
  * bounce bio.
  *
  * Caller must ensure bio has bio_crypt_ctx.
  *
  * Return: true on success; false on error (and bio->bi_status will be set
  *	   appropriately, and bio_endio() will have been called so bio
  *	   submission should abort).
  */
 bool __blk_crypto_bio_prep(struct bio **bio_ptr)
 {
 	struct bio *bio = *bio_ptr;
 	const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key;
 	struct blk_crypto_profile *profile;

 	/* Error if bio has no data. */
 	if (WARN_ON_ONCE(!bio_has_data(bio))) {
 		bio->bi_status = BLK_STS_IOERR;
 		goto fail;
 	}

 	if (!bio_crypt_check_alignment(bio)) {
 		bio->bi_status = BLK_STS_IOERR;
 		goto fail;
 	}

 	/*
 	 * Success if device supports the encryption context, or if we succeeded
 	 * in falling back to the crypto API.
 	 */
 	profile = bdev_get_queue(bio->bi_bdev)->crypto_profile;
 	if (__blk_crypto_cfg_supported(profile, &bc_key->crypto_cfg))
 		return true;

 	if (blk_crypto_fallback_bio_prep(bio_ptr))
 		return true;
 fail:
 	bio_endio(*bio_ptr);
 	return false;
 }

 int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio,
 			     gfp_t gfp_mask)
 {
 	if (!rq->crypt_ctx) {
 		rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
 		if (!rq->crypt_ctx)
 			return -ENOMEM;
 	}
 	*rq->crypt_ctx = *bio->bi_crypt_context;
 	return 0;
 }

 /**
  * blk_crypto_init_key() - Prepare a key for use with blk-crypto
  * @blk_key: Pointer to the blk_crypto_key to initialize.
  * @raw_key: Pointer to the raw key. Must be the correct length for the chosen
  *	     @crypto_mode; see blk_crypto_modes[].
  * @crypto_mode: identifier for the encryption algorithm to use
  * @dun_bytes: number of bytes that will be used to specify the DUN when this
  *	       key is used
  * @data_unit_size: the data unit size to use for en/decryption
  *
  * Return: 0 on success, -errno on failure.  The caller is responsible for
  *	   zeroizing both blk_key and raw_key when done with them.
  */
 int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key,
 			enum blk_crypto_mode_num crypto_mode,
 			unsigned int dun_bytes,
 			unsigned int data_unit_size)
 {
 	const struct blk_crypto_mode *mode;

 	memset(blk_key, 0, sizeof(*blk_key));

 	if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes))
 		return -EINVAL;

 	mode = &blk_crypto_modes[crypto_mode];
 	if (mode->keysize == 0)
 		return -EINVAL;

 	if (dun_bytes == 0 || dun_bytes > mode->ivsize)
 		return -EINVAL;

 	if (!is_power_of_2(data_unit_size))
 		return -EINVAL;

 	blk_key->crypto_cfg.crypto_mode = crypto_mode;
 	blk_key->crypto_cfg.dun_bytes = dun_bytes;
 	blk_key->crypto_cfg.data_unit_size = data_unit_size;
 	blk_key->data_unit_size_bits = ilog2(data_unit_size);
 	blk_key->size = mode->keysize;
 	memcpy(blk_key->raw, raw_key, mode->keysize);

 	return 0;
 }

 /*
  * Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the
  * request queue it's submitted to supports inline crypto, or the
  * blk-crypto-fallback is enabled and supports the cfg).
  */
 bool blk_crypto_config_supported(struct request_queue *q,
 				 const struct blk_crypto_config *cfg)
 {
 	return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) ||
 	       __blk_crypto_cfg_supported(q->crypto_profile, cfg);
 }

 /**
  * blk_crypto_start_using_key() - Start using a blk_crypto_key on a device
  * @key: A key to use on the device
  * @q: the request queue for the device
  *
  * Upper layers must call this function to ensure that either the hardware
  * supports the key's crypto settings, or the crypto API fallback has transforms
  * for the needed mode allocated and ready to go. This function may allocate
  * an skcipher, and *should not* be called from the data path, since that might
  * cause a deadlock
  *
  * Return: 0 on success; -ENOPKG if the hardware doesn't support the key and
  *	   blk-crypto-fallback is either disabled or the needed algorithm
  *	   is disabled in the crypto API; or another -errno code.
  */
 int blk_crypto_start_using_key(const struct blk_crypto_key *key,
 			       struct request_queue *q)
 {
 	if (__blk_crypto_cfg_supported(q->crypto_profile, &key->crypto_cfg))
 		return 0;
 	return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode);
 }

 /**
  * blk_crypto_evict_key() - Evict a key from any inline encryption hardware
  *			    it may have been programmed into
  * @q: The request queue who's associated inline encryption hardware this key
  *     might have been programmed into
  * @key: The key to evict
  *
  * Upper layers (filesystems) must call this function to ensure that a key is
  * evicted from any hardware that it might have been programmed into.  The key
  * must not be in use by any in-flight IO when this function is called.
  *
  * Return: 0 on success or if the key wasn't in any keyslot; -errno on error.
  */
 int blk_crypto_evict_key(struct request_queue *q,
 			 const struct blk_crypto_key *key)
 {
 	if (__blk_crypto_cfg_supported(q->crypto_profile, &key->crypto_cfg))
 		return __blk_crypto_evict_key(q->crypto_profile, key);

 	/*
 	 * If the request_queue didn't support the key, then blk-crypto-fallback
 	 * may have been used, so try to evict the key from blk-crypto-fallback.
 	 */
 	return blk_crypto_fallback_evict_key(key);
 }
 EXPORT_SYMBOL_GPL(blk_crypto_evict_key);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright 2019 Google LLC
	*/

	/*
	* Refer to Documentation/block/inline-encryption.rst for detailed explanation.
	*/

	#define pr_fmt(fmt) "blk-crypto: " fmt

	#include <linux/bio.h>
	#include <linux/blkdev.h>
	#include <linux/blk-crypto-profile.h>
	#include <linux/module.h>
	#include <linux/slab.h>

	#include "blk-crypto-internal.h"

	const struct blk_crypto_mode blk_crypto_modes[] = {
	[BLK_ENCRYPTION_MODE_AES_256_XTS] = {
	.name = "AES-256-XTS",
	.cipher_str = "xts(aes)",
	.keysize = 64,
	.ivsize = 16,
	},
	[BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = {
	.name = "AES-128-CBC-ESSIV",
	.cipher_str = "essiv(cbc(aes),sha256)",
	.keysize = 16,
	.ivsize = 16,
	},
	[BLK_ENCRYPTION_MODE_ADIANTUM] = {
	.name = "Adiantum",
	.cipher_str = "adiantum(xchacha12,aes)",
	.keysize = 32,
	.ivsize = 32,
	},
	};

	/*
	* This number needs to be at least (the number of threads doing IO
	* concurrently) * (maximum recursive depth of a bio), so that we don't
	* deadlock on crypt_ctx allocations. The default is chosen to be the same
	* as the default number of post read contexts in both EXT4 and F2FS.
	*/
	static int num_prealloc_crypt_ctxs = 128;

	module_param(num_prealloc_crypt_ctxs, int, 0444);
	MODULE_PARM_DESC(num_prealloc_crypt_ctxs,
	"Number of bio crypto contexts to preallocate");

	static struct kmem_cache *bio_crypt_ctx_cache;
	static mempool_t *bio_crypt_ctx_pool;

	static int __init bio_crypt_ctx_init(void)
	{
	size_t i;

	bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0);
	if (!bio_crypt_ctx_cache)
	goto out_no_mem;

	bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs,
	bio_crypt_ctx_cache);
	if (!bio_crypt_ctx_pool)
	goto out_no_mem;

	/* This is assumed in various places. */
	BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0);

	/* Sanity check that no algorithm exceeds the defined limits. */
	for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) {
	BUG_ON(blk_crypto_modes[i].keysize > BLK_CRYPTO_MAX_KEY_SIZE);
	BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE);
	}

	return 0;
	out_no_mem:
	panic("Failed to allocate mem for bio crypt ctxs\n");
	}
	subsys_initcall(bio_crypt_ctx_init);

	void bio_crypt_set_ctx(struct bio bio, const struct blk_crypto_key key,
	const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask)
	{
	struct bio_crypt_ctx *bc;

	/*
	* The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so
	* that the mempool_alloc() can't fail.
	*/
	WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM));

	bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);

	bc->bc_key = key;
	memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun));

	bio->bi_crypt_context = bc;
	}

	void __bio_crypt_free_ctx(struct bio *bio)
	{
	mempool_free(bio->bi_crypt_context, bio_crypt_ctx_pool);
	bio->bi_crypt_context = NULL;
	}

	int __bio_crypt_clone(struct bio dst, struct bio src, gfp_t gfp_mask)
	{
	dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
	if (!dst->bi_crypt_context)
	return -ENOMEM;
	dst->bi_crypt_context = src->bi_crypt_context;
	return 0;
	}

	/* Increments @dun by @inc, treating @dun as a multi-limb integer. */
	void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
	unsigned int inc)
	{
	int i;

	for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
	dun[i] += inc;
	/*
	* If the addition in this limb overflowed, then we need to
	* carry 1 into the next limb. Else the carry is 0.
	*/
	if (dun[i] < inc)
	inc = 1;
	else
	inc = 0;
	}
	}

	void __bio_crypt_advance(struct bio *bio, unsigned int bytes)
	{
	struct bio_crypt_ctx *bc = bio->bi_crypt_context;

	bio_crypt_dun_increment(bc->bc_dun,
	bytes >> bc->bc_key->data_unit_size_bits);
	}

	/*
	* Returns true if @bc->bc_dun plus @bytes converted to data units is equal to
	* @next_dun, treating the DUNs as multi-limb integers.
	*/
	bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc,
	unsigned int bytes,
	const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE])
	{
	int i;
	unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits;

	for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
	if (bc->bc_dun[i] + carry != next_dun[i])
	return false;
	/*
	* If the addition in this limb overflowed, then we need to
	* carry 1 into the next limb. Else the carry is 0.
	*/
	if ((bc->bc_dun[i] + carry) < carry)
	carry = 1;
	else
	carry = 0;
	}

	/* If the DUN wrapped through 0, don't treat it as contiguous. */
	return carry == 0;
	}

	/*
	* Checks that two bio crypt contexts are compatible - i.e. that
	* they are mergeable except for data_unit_num continuity.
	*/
	static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1,
	struct bio_crypt_ctx *bc2)
	{
	if (!bc1)
	return !bc2;

	return bc2 && bc1->bc_key == bc2->bc_key;
	}

	bool bio_crypt_rq_ctx_compatible(struct request rq, struct bio bio)
	{
	return bio_crypt_ctx_compatible(rq->crypt_ctx, bio->bi_crypt_context);
	}

	/*
	* Checks that two bio crypt contexts are compatible, and also
	* that their data_unit_nums are continuous (and can hence be merged)
	* in the order @bc1 followed by @bc2.
	*/
	bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes,
	struct bio_crypt_ctx *bc2)
	{
	if (!bio_crypt_ctx_compatible(bc1, bc2))
	return false;

	return !bc1 \|\| bio_crypt_dun_is_contiguous(bc1, bc1_bytes, bc2->bc_dun);
	}

	/* Check that all I/O segments are data unit aligned. */
	static bool bio_crypt_check_alignment(struct bio *bio)
	{
	const unsigned int data_unit_size =
	bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size;
	struct bvec_iter iter;
	struct bio_vec bv;

	bio_for_each_segment(bv, bio, iter) {
	if (!IS_ALIGNED(bv.bv_len \| bv.bv_offset, data_unit_size))
	return false;
	}

	return true;
	}

	blk_status_t __blk_crypto_init_request(struct request *rq)
	{
	return blk_crypto_get_keyslot(rq->q->crypto_profile,
	rq->crypt_ctx->bc_key,
	&rq->crypt_keyslot);
	}

	/**
	* __blk_crypto_free_request - Uninitialize the crypto fields of a request.
	*
	* @rq: The request whose crypto fields to uninitialize.
	*
	* Completely uninitializes the crypto fields of a request. If a keyslot has
	* been programmed into some inline encryption hardware, that keyslot is
	* released. The rq->crypt_ctx is also freed.
	*/
	void __blk_crypto_free_request(struct request *rq)
	{
	blk_crypto_put_keyslot(rq->crypt_keyslot);
	mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool);
	blk_crypto_rq_set_defaults(rq);
	}

	/**
	* __blk_crypto_bio_prep - Prepare bio for inline encryption
	*
	* @bio_ptr: pointer to original bio pointer
	*
	* If the bio crypt context provided for the bio is supported by the underlying
	* device's inline encryption hardware, do nothing.
	*
	* Otherwise, try to perform en/decryption for this bio by falling back to the
	* kernel crypto API. When the crypto API fallback is used for encryption,
	* blk-crypto may choose to split the bio into 2 - the first one that will
	* continue to be processed and the second one that will be resubmitted via
	* submit_bio_noacct. A bounce bio will be allocated to encrypt the contents
	* of the aforementioned "first one", and *bio_ptr will be updated to this
	* bounce bio.
	*
	* Caller must ensure bio has bio_crypt_ctx.
	*
	* Return: true on success; false on error (and bio->bi_status will be set
	* appropriately, and bio_endio() will have been called so bio
	* submission should abort).
	*/
	bool __blk_crypto_bio_prep(struct bio **bio_ptr)
	{
	struct bio bio = bio_ptr;
	const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key;
	struct blk_crypto_profile *profile;

	/* Error if bio has no data. */
	if (WARN_ON_ONCE(!bio_has_data(bio))) {
	bio->bi_status = BLK_STS_IOERR;
	goto fail;
	}

	if (!bio_crypt_check_alignment(bio)) {
	bio->bi_status = BLK_STS_IOERR;
	goto fail;
	}

	/*
	* Success if device supports the encryption context, or if we succeeded
	* in falling back to the crypto API.
	*/
	profile = bdev_get_queue(bio->bi_bdev)->crypto_profile;
	if (__blk_crypto_cfg_supported(profile, &bc_key->crypto_cfg))
	return true;

	if (blk_crypto_fallback_bio_prep(bio_ptr))
	return true;
	fail:
	bio_endio(*bio_ptr);
	return false;
	}

	int __blk_crypto_rq_bio_prep(struct request rq, struct bio bio,
	gfp_t gfp_mask)
	{
	if (!rq->crypt_ctx) {
	rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
	if (!rq->crypt_ctx)
	return -ENOMEM;
	}
	rq->crypt_ctx = bio->bi_crypt_context;
	return 0;
	}

	/**
	* blk_crypto_init_key() - Prepare a key for use with blk-crypto
	* @blk_key: Pointer to the blk_crypto_key to initialize.
	* @raw_key: Pointer to the raw key. Must be the correct length for the chosen
	* @crypto_mode; see blk_crypto_modes[].
	* @crypto_mode: identifier for the encryption algorithm to use
	* @dun_bytes: number of bytes that will be used to specify the DUN when this
	* key is used
	* @data_unit_size: the data unit size to use for en/decryption
	*
	* Return: 0 on success, -errno on failure. The caller is responsible for
	* zeroizing both blk_key and raw_key when done with them.
	*/
	int blk_crypto_init_key(struct blk_crypto_key blk_key, const u8 raw_key,
	enum blk_crypto_mode_num crypto_mode,
	unsigned int dun_bytes,
	unsigned int data_unit_size)
	{
	const struct blk_crypto_mode *mode;

	memset(blk_key, 0, sizeof(*blk_key));

	if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes))
	return -EINVAL;

	mode = &blk_crypto_modes[crypto_mode];
	if (mode->keysize == 0)
	return -EINVAL;

	if (dun_bytes == 0 \|\| dun_bytes > mode->ivsize)
	return -EINVAL;

	if (!is_power_of_2(data_unit_size))
	return -EINVAL;

	blk_key->crypto_cfg.crypto_mode = crypto_mode;
	blk_key->crypto_cfg.dun_bytes = dun_bytes;
	blk_key->crypto_cfg.data_unit_size = data_unit_size;
	blk_key->data_unit_size_bits = ilog2(data_unit_size);
	blk_key->size = mode->keysize;
	memcpy(blk_key->raw, raw_key, mode->keysize);

	return 0;
	}

	/*
	* Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the
	* request queue it's submitted to supports inline crypto, or the
	* blk-crypto-fallback is enabled and supports the cfg).
	*/
	bool blk_crypto_config_supported(struct request_queue *q,
	const struct blk_crypto_config *cfg)
	{
	return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) \|\|
	__blk_crypto_cfg_supported(q->crypto_profile, cfg);
	}

	/**
	* blk_crypto_start_using_key() - Start using a blk_crypto_key on a device
	* @key: A key to use on the device
	* @q: the request queue for the device
	*
	* Upper layers must call this function to ensure that either the hardware
	* supports the key's crypto settings, or the crypto API fallback has transforms
	* for the needed mode allocated and ready to go. This function may allocate
	* an skcipher, and should not be called from the data path, since that might
	* cause a deadlock
	*
	* Return: 0 on success; -ENOPKG if the hardware doesn't support the key and
	* blk-crypto-fallback is either disabled or the needed algorithm
	* is disabled in the crypto API; or another -errno code.
	*/
	int blk_crypto_start_using_key(const struct blk_crypto_key *key,
	struct request_queue *q)
	{
	if (__blk_crypto_cfg_supported(q->crypto_profile, &key->crypto_cfg))
	return 0;
	return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode);
	}

	/**
	* blk_crypto_evict_key() - Evict a key from any inline encryption hardware
	* it may have been programmed into
	* @q: The request queue who's associated inline encryption hardware this key
	* might have been programmed into
	* @key: The key to evict
	*
	* Upper layers (filesystems) must call this function to ensure that a key is
	* evicted from any hardware that it might have been programmed into. The key
	* must not be in use by any in-flight IO when this function is called.
	*
	* Return: 0 on success or if the key wasn't in any keyslot; -errno on error.
	*/
	int blk_crypto_evict_key(struct request_queue *q,
	const struct blk_crypto_key *key)
	{
	if (__blk_crypto_cfg_supported(q->crypto_profile, &key->crypto_cfg))
	return __blk_crypto_evict_key(q->crypto_profile, key);

	/*
	* If the request_queue didn't support the key, then blk-crypto-fallback
	* may have been used, so try to evict the key from blk-crypto-fallback.
	*/
	return blk_crypto_fallback_evict_key(key);
	}
	EXPORT_SYMBOL_GPL(blk_crypto_evict_key);