1 files changed, 194 insertions, 0 deletions
diff --git a/include/linux/blk-crypto.h b/include/linux/blk-crypto.h
new file mode 100644
index 000000000000..58b0c5254a67
--- /dev/null
+++ b/include/linux/blk-crypto.h
@@ -0,0 +1,194 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2019 Google LLC
+ */
+
+#ifndef __LINUX_BLK_CRYPTO_H
+#define __LINUX_BLK_CRYPTO_H
+
+#include <linux/minmax.h>
+#include <linux/types.h>
+#include <uapi/linux/blk-crypto.h>
+
+enum blk_crypto_mode_num {
+	BLK_ENCRYPTION_MODE_INVALID,
+	BLK_ENCRYPTION_MODE_AES_256_XTS,
+	BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV,
+	BLK_ENCRYPTION_MODE_ADIANTUM,
+	BLK_ENCRYPTION_MODE_SM4_XTS,
+	BLK_ENCRYPTION_MODE_MAX,
+};
+
+/*
+ * Supported types of keys.  Must be bitflags due to their use in
+ * blk_crypto_profile::key_types_supported.
+ */
+enum blk_crypto_key_type {
+	/*
+	 * Raw keys (i.e. "software keys").  These keys are simply kept in raw,
+	 * plaintext form in kernel memory.
+	 */
+	BLK_CRYPTO_KEY_TYPE_RAW = 0x1,
+
+	/*
+	 * Hardware-wrapped keys.  These keys are only present in kernel memory
+	 * in ephemerally-wrapped form, and they can only be unwrapped by
+	 * dedicated hardware.  For details, see the "Hardware-wrapped keys"
+	 * section of Documentation/block/inline-encryption.rst.
+	 */
+	BLK_CRYPTO_KEY_TYPE_HW_WRAPPED = 0x2,
+};
+
+/*
+ * Currently the maximum raw key size is 64 bytes, as that is the key size of
+ * BLK_ENCRYPTION_MODE_AES_256_XTS which takes the longest key.
+ *
+ * The maximum hardware-wrapped key size depends on the hardware's key wrapping
+ * algorithm, which is a hardware implementation detail, so it isn't precisely
+ * specified.  But currently 128 bytes is plenty in practice.  Implementations
+ * are recommended to wrap a 32-byte key for the hardware KDF with AES-256-GCM,
+ * which should result in a size closer to 64 bytes than 128.
+ *
+ * Both of these values can trivially be increased if ever needed.
+ */
+#define BLK_CRYPTO_MAX_RAW_KEY_SIZE		64
+#define BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE	128
+
+#define BLK_CRYPTO_MAX_ANY_KEY_SIZE \
+	MAX(BLK_CRYPTO_MAX_RAW_KEY_SIZE, BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE)
+
+/*
+ * Size of the "software secret" which can be derived from a hardware-wrapped
+ * key.  This is currently always 32 bytes.  Note, the choice of 32 bytes
+ * assumes that the software secret is only used directly for algorithms that
+ * don't require more than a 256-bit key to get the desired security strength.
+ * If it were to be used e.g. directly as an AES-256-XTS key, then this would
+ * need to be increased (which is possible if hardware supports it, but care
+ * would need to be taken to avoid breaking users who need exactly 32 bytes).
+ */
+#define BLK_CRYPTO_SW_SECRET_SIZE	32
+
+/**
+ * struct blk_crypto_config - an inline encryption key's crypto configuration
+ * @crypto_mode: encryption algorithm this key is for
+ * @data_unit_size: the data unit size for all encryption/decryptions with this
+ *	key.  This is the size in bytes of each individual plaintext and
+ *	ciphertext.  This is always a power of 2.  It might be e.g. the
+ *	filesystem block size or the disk sector size.
+ * @dun_bytes: the maximum number of bytes of DUN used when using this key
+ * @key_type: the type of this key -- either raw or hardware-wrapped
+ */
+struct blk_crypto_config {
+	enum blk_crypto_mode_num crypto_mode;
+	unsigned int data_unit_size;
+	unsigned int dun_bytes;
+	enum blk_crypto_key_type key_type;
+};
+
+/**
+ * struct blk_crypto_key - an inline encryption key
+ * @crypto_cfg: the crypto mode, data unit size, key type, and other
+ *		characteristics of this key and how it will be used
+ * @data_unit_size_bits: log2 of data_unit_size
+ * @size: size of this key in bytes.  The size of a raw key is fixed for a given
+ *	  crypto mode, but the size of a hardware-wrapped key can vary.
+ * @bytes: the bytes of this key.  Only the first @size bytes are significant.
+ *
+ * A blk_crypto_key is immutable once created, and many bios can reference it at
+ * the same time.  It must not be freed until all bios using it have completed
+ * and it has been evicted from all devices on which it may have been used.
+ */
+struct blk_crypto_key {
+	struct blk_crypto_config crypto_cfg;
+	unsigned int data_unit_size_bits;
+	unsigned int size;
+	u8 bytes[BLK_CRYPTO_MAX_ANY_KEY_SIZE];
+};
+
+#define BLK_CRYPTO_MAX_IV_SIZE		32
+#define BLK_CRYPTO_DUN_ARRAY_SIZE	(BLK_CRYPTO_MAX_IV_SIZE / sizeof(u64))
+
+/**
+ * struct bio_crypt_ctx - an inline encryption context
+ * @bc_key: the key, algorithm, and data unit size to use
+ * @bc_dun: the data unit number (starting IV) to use
+ *
+ * A bio_crypt_ctx specifies that the contents of the bio will be encrypted (for
+ * write requests) or decrypted (for read requests) inline by the storage device
+ * or controller, or by the crypto API fallback.
+ */
+struct bio_crypt_ctx {
+	const struct blk_crypto_key	*bc_key;
+	u64				bc_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
+};
+
+#include <linux/blk_types.h>
+#include <linux/blkdev.h>
+
+#ifdef CONFIG_BLK_INLINE_ENCRYPTION
+
+static inline bool bio_has_crypt_ctx(struct bio *bio)
+{
+	return bio->bi_crypt_context;
+}
+
+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);
+
+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 blk_crypto_init_key(struct blk_crypto_key *blk_key,
+			const u8 *key_bytes, size_t key_size,
+			enum blk_crypto_key_type key_type,
+			enum blk_crypto_mode_num crypto_mode,
+			unsigned int dun_bytes,
+			unsigned int data_unit_size);
+
+int blk_crypto_start_using_key(struct block_device *bdev,
+			       const struct blk_crypto_key *key);
+
+void blk_crypto_evict_key(struct block_device *bdev,
+			  const struct blk_crypto_key *key);
+
+bool blk_crypto_config_supported_natively(struct block_device *bdev,
+					  const struct blk_crypto_config *cfg);
+bool blk_crypto_config_supported(struct block_device *bdev,
+				 const struct blk_crypto_config *cfg);
+
+int blk_crypto_derive_sw_secret(struct block_device *bdev,
+				const u8 *eph_key, size_t eph_key_size,
+				u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]);
+
+#else /* CONFIG_BLK_INLINE_ENCRYPTION */
+
+static inline bool bio_has_crypt_ctx(struct bio *bio)
+{
+	return false;
+}
+
+#endif /* CONFIG_BLK_INLINE_ENCRYPTION */
+
+int __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask);
+/**
+ * bio_crypt_clone - clone bio encryption context
+ * @dst: destination bio
+ * @src: source bio
+ * @gfp_mask: memory allocation flags
+ *
+ * If @src has an encryption context, clone it to @dst.
+ *
+ * Return: 0 on success, -ENOMEM if out of memory.  -ENOMEM is only possible if
+ *	   @gfp_mask doesn't include %__GFP_DIRECT_RECLAIM.
+ */
+static inline int bio_crypt_clone(struct bio *dst, struct bio *src,
+				  gfp_t gfp_mask)
+{
+	if (bio_has_crypt_ctx(src))
+		return __bio_crypt_clone(dst, src, gfp_mask);
+	return 0;
+}
+
+#endif /* __LINUX_BLK_CRYPTO_H */