Linux Virtualization - Oct 2019 - [PATCH v2 01/27] crypto: virtio - implement missing support for output IVs

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 at redhat.com>
Cc: Jason Wang <jasowang at redhat.com>
Cc: Gonglei <arei.gonglei at huawei.com>
Cc: virtualization at lists.linux-foundation.org
Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
---
 drivers/crypto/virtio/virtio_crypto_algs.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/crypto/virtio/virtio_crypto_algs.c
b/drivers/crypto/virtio/virtio_crypto_algs.c
index 42d19205166b..65ec10800137 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;
@@ -563,6 +568,10 @@ 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);
-- 
2.20.1