Re: [PATCH 3/4] crypto: arm64/aes-ce-ccm - fix decrypt path with new skcipher interface

[Herbert Xu <herbert@gondor.apana.org.au>]

On Wed, Nov 30, 2016 at 09:14:07PM +0800, Herbert Xu wrote:
> On Tue, Nov 29, 2016 at 01:05:32PM +0000, Ard Biesheuvel wrote:
> > The new skcipher walk interface does not take into account whether we
> > are encrypting or decrypting. In the latter case, the walk should
> > disregard the MAC. Fix this in the arm64 CE driver.
> > 
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> 
> Thanks for the patch.  I'm going to build this into the AEAD walker
> instead, by providing separate entry points for encryption and
> decryption.  Like this,
> 
> Subject: crypto: skcipher - Add separate walker for AEAD decryption

---8<---
Subject: crypto: arm64/aes-ce-ccm - Fix AEAD decryption length

This patch fixes the ARM64 CE CCM implementation decryption by
using skcipher_walk_aead_decrypt instead of skcipher_walk_aead,
which ensures the correct length is used when doing the walk.

Fixes: cf2c0fe74084 ("crypto: aes-ce-ccm - Use skcipher walk interface")
Reported-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/arm64/crypto/aes-ce-ccm-glue.c b/arch/arm64/crypto/aes-ce-ccm-glue.c
index d4f3568..cc5515d 100644
--- a/arch/arm64/crypto/aes-ce-ccm-glue.c
+++ b/arch/arm64/crypto/aes-ce-ccm-glue.c
@@ -167,7 +167,7 @@ static int ccm_encrypt(struct aead_request *req)
 	/* preserve the original iv for the final round */
 	memcpy(buf, req->iv, AES_BLOCK_SIZE);
 
-	err = skcipher_walk_aead(&walk, req, true);
+	err = skcipher_walk_aead_encrypt(&walk, req, true);
 
 	while (walk.nbytes) {
 		u32 tail = walk.nbytes % AES_BLOCK_SIZE;
@@ -219,7 +219,7 @@ static int ccm_decrypt(struct aead_request *req)
 	/* preserve the original iv for the final round */
 	memcpy(buf, req->iv, AES_BLOCK_SIZE);
 
-	err = skcipher_walk_aead(&walk, req, true);
+	err = skcipher_walk_aead_decrypt(&walk, req, true);
 
 	while (walk.nbytes) {
 		u32 tail = walk.nbytes % AES_BLOCK_SIZE;

-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt