[PATCH 3.2 05/46] crypto: gcm - fix rfc4543 to handle async crypto correctly

[Ben Hutchings]

3.2.81-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jussi Kivilinna <jussi.kivilinna@xxxxxx>

commit d733ac90f9fe8ac284e523f9920b507555b12f6d upstream.

If the gcm cipher used by rfc4543 does not complete request immediately,
the authentication tag is not copied to destination buffer. Patch adds
correct async logic for this case.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@xxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 crypto/gcm.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

--- a/crypto/gcm.c
+++ b/crypto/gcm.c
@@ -1103,6 +1103,21 @@ static int crypto_rfc4543_setauthsize(st
 	return crypto_aead_setauthsize(ctx->child, authsize);
 }
 
+static void crypto_rfc4543_done(struct crypto_async_request *areq, int err)
+{
+	struct aead_request *req = areq->data;
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+	struct crypto_rfc4543_req_ctx *rctx = crypto_rfc4543_reqctx(req);
+
+	if (!err) {
+		scatterwalk_map_and_copy(rctx->auth_tag, req->dst,
+					 req->cryptlen,
+					 crypto_aead_authsize(aead), 1);
+	}
+
+	aead_request_complete(req, err);
+}
+
 static struct aead_request *crypto_rfc4543_crypt(struct aead_request *req,
 						 int enc)
 {
@@ -1159,8 +1174,8 @@ static struct aead_request *crypto_rfc45
 	scatterwalk_crypto_chain(assoc, payload, 0, 2);
 
 	aead_request_set_tfm(subreq, ctx->child);
-	aead_request_set_callback(subreq, req->base.flags, req->base.complete,
-				  req->base.data);
+	aead_request_set_callback(subreq, req->base.flags, crypto_rfc4543_done,
+				  req);
 	aead_request_set_crypt(subreq, cipher, cipher, enc ? 0 : authsize, iv);
 	aead_request_set_assoc(subreq, assoc, assoclen);