dm-inlinecrypt: add target for inline block device encryption

Add a new device-mapper target "dm-inlinecrypt" that is similar to
dm-crypt but uses the blk-crypto API instead of the regular crypto API.
This allows it to take advantage of inline encryption hardware such as
that commonly built into UFS host controllers.

The table syntax matches dm-crypt's, but for now only a stripped-down
set of parameters is supported.  For example, for now AES-256-XTS is the
only supported cipher.

dm-inlinecrypt is based on Android's dm-default-key with the
controversial passthrough support removed.  Note that due to the removal
of passthrough support, use of dm-inlinecrypt in combination with
fscrypt causes double encryption of file contents (similar to dm-crypt +
fscrypt), with the fscrypt layer not being able to use the inline
encryption hardware.  This makes dm-inlinecrypt unusable on systems such
as Android that use fscrypt and where a more optimized approach is
needed.  It is however suitable as a replacement for dm-crypt.

dm-inlinecrypt supports both keyring key and hex key, the former avoids
the key to be exposed in dm-table message. Similar to dm-default-key in
Android, it will fallabck to the software block crypto once the inline
crypto hardware cannot support the expected cipher.

Test:
dmsetup create inlinecrypt_logon --table "0 `blockdev --getsz $1` \
inlinecrypt aes-xts-plain64 :64:logon:fde:dminlinecrypt_test_key 0 $1 0"

Signed-off-by: Eric Biggers <[email protected]>
Signed-off-by: Linlin Zhang <[email protected]>

Author: ebiggers

drivers/md/Kconfig

@@ -315,6 +315,16 @@ config DM_CRYPT
 
 	  If unsure, say N.
 
+config DM_INLINECRYPT
+	tristate "Inline encryption target support"
+	depends on BLK_DEV_DM
+	depends on BLK_INLINE_ENCRYPTION
+	help
+	  This device-mapper target is similar to dm-crypt, but it uses the
+	  blk-crypto API instead of the regular crypto API. This allows it to
+	  take advantage of inline encryption hardware such as that commonly
+	  built into UFS host controllers.
+
 config DM_SNAPSHOT
        tristate "Snapshot target"
        depends on BLK_DEV_DM

drivers/md/Makefile

@@ -55,6 +55,7 @@ obj-$(CONFIG_DM_UNSTRIPED)	+= dm-unstripe.o
 obj-$(CONFIG_DM_BUFIO)		+= dm-bufio.o
 obj-$(CONFIG_DM_BIO_PRISON)	+= dm-bio-prison.o
 obj-$(CONFIG_DM_CRYPT)		+= dm-crypt.o
+obj-$(CONFIG_DM_INLINECRYPT)	+= dm-inlinecrypt.o
 obj-$(CONFIG_DM_DELAY)		+= dm-delay.o
 obj-$(CONFIG_DM_DUST)		+= dm-dust.o
 obj-$(CONFIG_DM_FLAKEY)		+= dm-flakey.o