[PATCH 10/12] crypto: axis - fix XTS unaligned block size handling

[Vincent Whitchurch]

The hardware does not implement ciphertext stealing so fallback to
software if the data length is not aligned to the block size.  Fixes
this kind of errors with CRYPTO_MANAGER_EXTRA_TESTS:

 alg: skcipher: artpec6-xts-aes encryption test failed (wrong result) on
 test vector "random: len=151 klen=64", cfg="random: inplace_two_sglists
 use_digest nosimd src_divs=[96.95%@+1949, 3.5%@+30]"

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
---
 drivers/crypto/axis/artpec6_crypto.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/axis/artpec6_crypto.c b/drivers/crypto/axis/artpec6_crypto.c
index 3b47faa06606..5eccb5a3a52e 100644
--- a/drivers/crypto/axis/artpec6_crypto.c
+++ b/drivers/crypto/axis/artpec6_crypto.c
@@ -1309,6 +1309,24 @@ static int artpec6_crypto_ctr_decrypt(struct skcipher_request *req)
 	return artpec6_crypto_ctr_crypt(req, false);
 }
 
+static int artpec6_crypto_xts_encrypt(struct skcipher_request *req)
+{
+	/* Hardware does not implement ciphertext stealing */
+	if (!IS_ALIGNED(req->cryptlen, AES_BLOCK_SIZE))
+		return artpec6_crypto_crypt_fallback(req, true);
+
+	return artpec6_crypto_encrypt(req);
+}
+
+static int artpec6_crypto_xts_decrypt(struct skcipher_request *req)
+{
+	/* Hardware does not implement ciphertext stealing */
+	if (!IS_ALIGNED(req->cryptlen, AES_BLOCK_SIZE))
+		return artpec6_crypto_crypt_fallback(req, false);
+
+	return artpec6_crypto_decrypt(req);
+}
+
 /*
  * AEAD functions
  */
@@ -2928,8 +2946,8 @@ static struct skcipher_alg crypto_algos[] = {
 		.max_keysize = 2*AES_MAX_KEY_SIZE,
 		.ivsize = 16,
 		.setkey = artpec6_crypto_xts_set_key,
-		.encrypt = artpec6_crypto_encrypt,
-		.decrypt = artpec6_crypto_decrypt,
+		.encrypt = artpec6_crypto_xts_encrypt,
+		.decrypt = artpec6_crypto_xts_decrypt,
 		.init = artpec6_crypto_aes_xts_init,
 		.exit = artpec6_crypto_aes_exit,
 	},
-- 
2.34.1