1 files changed, 376 insertions, 0 deletions
diff --git a/block/blk-crypto.c b/block/blk-crypto.c
new file mode 100644
index 000000000000..25b981257f5f
--- /dev/null
+++ b/block/blk-crypto.c
@@ -0,0 +1,376 @@
+// 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/keyslot-manager.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] = {
+		.keysize = 64,
+		.ivsize = 16,
+	},
+	[BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = {
+		.keysize = 16,
+		.ivsize = 16,
+	},
+	[BLK_ENCRYPTION_MODE_ADIANTUM] = {
+		.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 = 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;
+}
+
+void __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);
+	*dst->bi_crypt_context = *src->bi_crypt_context;
+}
+EXPORT_SYMBOL_GPL(__bio_crypt_clone);
+
+/* 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_ksm_get_slot_for_key(rq->q->ksm, 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_ksm_put_slot(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
+ *
+ * Succeeds if the bio doesn't have inline encryption enabled or if the bio
+ * crypt context provided for the bio is supported by the underlying device's
+ * inline encryption hardware. Ends the bio with error otherwise.
+ *
+ * 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;
+	blk_status_t blk_st = BLK_STS_IOERR;
+
+	/* Error if bio has no data. */
+	if (WARN_ON_ONCE(!bio_has_data(bio)))
+		goto fail;
+
+	if (!bio_crypt_check_alignment(bio))
+		goto fail;
+
+	/*
+	 * Success if device supports the encryption context.
+	 */
+	if (!blk_ksm_crypto_cfg_supported(bio->bi_disk->queue->ksm,
+					  &bc_key->crypto_cfg)) {
+		blk_st = BLK_STS_NOTSUPP;
+		goto fail;
+	}
+
+	return true;
+fail:
+	(*bio_ptr)->bi_status = blk_st;
+	bio_endio(*bio_ptr);
+	return false;
+}
+
+/**
+ * __blk_crypto_rq_bio_prep - Prepare a request's crypt_ctx when its first bio
+ *			      is inserted
+ *
+ * @rq: The request to prepare
+ * @bio: The first bio being inserted into the request
+ * @gfp_mask: gfp mask
+ */
+void __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);
+	*rq->crypt_ctx = *bio->bi_crypt_context;
+}
+
+/**
+ * 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 > BLK_CRYPTO_MAX_IV_SIZE)
+		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;
+}
+
+bool blk_crypto_config_supported(struct request_queue *q,
+				 const struct blk_crypto_config *cfg)
+{
+	return blk_ksm_crypto_cfg_supported(q->ksm, 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 the hardware supports
+ * the key's crypto settings.
+ *
+ * Return: 0 on success; -ENOPKG if the hardware doesn't support the key
+ */
+int blk_crypto_start_using_key(const struct blk_crypto_key *key,
+			       struct request_queue *q)
+{
+	if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg))
+		return 0;
+	return -ENOPKG;
+}
+
+/**
+ * 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 key is not present in the q's ksm, -err on error.
+ */
+int blk_crypto_evict_key(struct request_queue *q,
+			 const struct blk_crypto_key *key)
+{
+	if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg))
+		return blk_ksm_evict_key(q->ksm, key);
+
+	return 0;
+}