From c6038d48d74d7682e43fa881d94ed7b3754bfe0a Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@kernel.org>
Date: Sat, 9 Nov 2019 18:09:26 +0100
Subject: [PATCH] crypto: virtio - implement missing support for output IVs

commit 500e6807ce93b1fdc7d5b827c5cc167cc35630db upstream.

In order to allow for CBC to be chained, which is something that the
CTS template relies upon, implementations of CBC need to pass the
IV to be used for subsequent invocations via the IV buffer. This was
not implemented yet for virtio-crypto so implement it now.

Fixes: dbaf0624ffa5 ("crypto: add virtio-crypto driver")
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Gonglei <arei.gonglei@huawei.com>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/crypto/virtio/virtio_crypto_algs.c b/drivers/crypto/virtio/virtio_crypto_algs.c
index 963f16a6f9cf..a489809a339e 100644
--- a/drivers/crypto/virtio/virtio_crypto_algs.c
+++ b/drivers/crypto/virtio/virtio_crypto_algs.c
@@ -437,6 +437,11 @@ __virtio_crypto_ablkcipher_do_req(struct virtio_crypto_sym_request *vc_sym_req,
 		goto free;
 	}
 	memcpy(iv, req->info, ivsize);
+	if (!vc_sym_req->encrypt)
+		scatterwalk_map_and_copy(req->info, req->src,
+					 req->nbytes - AES_BLOCK_SIZE,
+					 AES_BLOCK_SIZE, 0);
+
 	sg_init_one(&iv_sg, iv, ivsize);
 	sgs[num_out++] = &iv_sg;
 	vc_sym_req->iv = iv;
@@ -573,6 +578,10 @@ static void virtio_crypto_ablkcipher_finalize_req(
 	struct ablkcipher_request *req,
 	int err)
 {
+	if (vc_sym_req->encrypt)
+		scatterwalk_map_and_copy(req->info, req->dst,
+					 req->nbytes - AES_BLOCK_SIZE,
+					 AES_BLOCK_SIZE, 0);
 	crypto_finalize_ablkcipher_request(vc_sym_req->base.dataq->engine,
 					   req, err);
 	kzfree(vc_sym_req->iv);
-- 
2.7.4