[PATCH v7 08/11] crypto: qce: skcipher: Improve the conditions for requesting AES fallback cipher

From: Thara Gopinath
Date: Thu Feb 11 2021 - 15:08:55 EST


The following are the conditions for requesting AES fallback cipher.
- AES-192
- AES-XTS request with len <= 512 byte (Allow messages of length
less than 512 bytes for all other AES encryption algorithms other
than AES XTS)
- AES-XTS request with len > QCE_SECTOR_SIZE and is not a multiple
of it

Signed-off-by: Thara Gopinath <thara.gopinath@xxxxxxxxxx>
---
drivers/crypto/qce/skcipher.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/crypto/qce/skcipher.c b/drivers/crypto/qce/skcipher.c
index 11a2a30631af..2e6ab1d33a31 100644
--- a/drivers/crypto/qce/skcipher.c
+++ b/drivers/crypto/qce/skcipher.c
@@ -274,14 +274,19 @@ static int qce_skcipher_crypt(struct skcipher_request *req, int encrypt)
if (!IS_ALIGNED(req->cryptlen, blocksize))
return -EINVAL;

- /* qce is hanging when AES-XTS request len > QCE_SECTOR_SIZE and
- * is not a multiple of it; pass such requests to the fallback
+ /*
+ * Conditions for requesting a fallback cipher
+ * AES-192 (not supported by crypto engine (CE))
+ * AES-XTS request with len <= 512 byte (not recommended to use CE)
+ * AES-XTS request with len > QCE_SECTOR_SIZE and
+ * is not a multiple of it.(Revisit this condition to check if it is
+ * needed in all versions of CE)
*/
if (IS_AES(rctx->flags) &&
- (((keylen != AES_KEYSIZE_128 && keylen != AES_KEYSIZE_256) ||
- req->cryptlen <= aes_sw_max_len) ||
- (IS_XTS(rctx->flags) && req->cryptlen > QCE_SECTOR_SIZE &&
- req->cryptlen % QCE_SECTOR_SIZE))) {
+ ((keylen != AES_KEYSIZE_128 && keylen != AES_KEYSIZE_256) ||
+ (IS_XTS(rctx->flags) && ((req->cryptlen <= aes_sw_max_len) ||
+ (req->cryptlen > QCE_SECTOR_SIZE &&
+ req->cryptlen % QCE_SECTOR_SIZE))))) {
skcipher_request_set_tfm(&rctx->fallback_req, ctx->fallback);
skcipher_request_set_callback(&rctx->fallback_req,
req->base.flags,
--
2.25.1