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

From: Thara Gopinath <thara.gopinath@linaro.org>
To: herbert@gondor.apana.org.au, davem@davemloft.net,
	bjorn.andersson@linaro.org
Cc: ebiggers@google.com, ardb@kernel.org, sivaprak@codeaurora.org,
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v7 08/11] crypto: qce: skcipher: Improve the conditions for requesting AES fallback cipher
Date: Thu, 11 Feb 2021 15:01:25 -0500	[thread overview]
Message-ID: <20210211200128.2886388-9-thara.gopinath@linaro.org> (raw)
In-Reply-To: <20210211200128.2886388-1-thara.gopinath@linaro.org>

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@linaro.org>
---
 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

