BACKPORT: crypto: blake2b - add blake2b generic implementation

The patch brings support of several BLAKE2 variants (2b with various
digest lengths).  The keyed digest is supported, using tfm->setkey call.
The in-tree user will be btrfs (for checksumming), we're going to use
the BLAKE2b-256 variant.

The code is reference implementation taken from the official sources and
modified in terms of kernel coding style (whitespace, comments, uintXX_t
-> uXX types, removed unused prototypes and #ifdefs, removed testing
code, changed secure_zero_memory -> memzero_explicit, used own helpers
for unaligned reads/writes and rotations).

Further changes removed sanity checks of key length or output size,
these values are verified in the crypto API callbacks or hardcoded in
shash_alg and not exposed to users.

Signed-off-by: David Sterba <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>

(cherry picked from commit 91d689337fe8b7703608a2ec39aae700b99f3933)

Conflicts:
	crypto/Kconfig
	crypto/Makefile

(trivial conflicts due to blake2s having been backported already)

Bug: 178411248
Change-Id: Ic4c2314b146434a5842facf56e58d3602bacc7d5
Signed-off-by: Eric Biggers <[email protected]>

crypto/Kconfig

@@ -663,6 +663,23 @@ config CRYPTO_BLAKE2S_X86
 	select CRYPTO_LIB_BLAKE2S_GENERIC
 	select CRYPTO_ARCH_HAVE_LIB_BLAKE2S
 
+config CRYPTO_BLAKE2B
+	tristate "BLAKE2b digest algorithm"
+	select CRYPTO_HASH
+	help
+	  Implementation of cryptographic hash function BLAKE2b (or just BLAKE2),
+	  optimized for 64bit platforms and can produce digests of any size
+	  between 1 to 64.  The keyed hash is also implemented.
+
+	  This module provides the following algorithms:
+
+	  - blake2b-160
+	  - blake2b-256
+	  - blake2b-384
+	  - blake2b-512
+
+	  See https://blake2.net for further information.
+
 config CRYPTO_CRCT10DIF
 	tristate "CRCT10DIF algorithm"
 	select CRYPTO_HASH