linux-kernel - [PATCH v2 7/9] crypto: virtio: Add IV buffer in structure virtio_crypto_sym

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Message-Id: <20251204112502.2659544-1-maobibo@loongson.cn>
Date: Thu,  4 Dec 2025 19:25:02 +0800
From: Bibo Mao <maobibo@...ngson.cn>
To: Gonglei <arei.gonglei@...wei.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>
Cc: virtualization@...ts.linux.dev,
	linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 7/9] crypto: virtio: Add IV buffer in structure virtio_crypto_sym_request

Add IV buffer in structure virtio_crypto_sym_request to avoid unnecessary
IV buffer allocation in encrypt/decrypt process. And IV buffer is cleared
when encrypt/decrypt is finished.

Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
---
 .../virtio/virtio_crypto_skcipher_algs.c      | 20 +++++++------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/drivers/crypto/virtio/virtio_crypto_skcipher_algs.c b/drivers/crypto/virtio/virtio_crypto_skcipher_algs.c
index a7c7c726e6d9..c911b7ba8f13 100644
--- a/drivers/crypto/virtio/virtio_crypto_skcipher_algs.c
+++ b/drivers/crypto/virtio/virtio_crypto_skcipher_algs.c
@@ -30,9 +30,9 @@ struct virtio_crypto_sym_request {
 
 	/* Cipher or aead */
 	uint32_t type;
-	uint8_t *iv;
 	/* Encryption? */
 	bool encrypt;
+	uint8_t iv[0];
 };
 
 struct virtio_crypto_algo {
@@ -402,12 +402,7 @@ __virtio_crypto_skcipher_do_req(struct virtio_crypto_sym_request *vc_sym_req,
 	 * Avoid to do DMA from the stack, switch to using
 	 * dynamically-allocated for the IV
 	 */
-	iv = kzalloc_node(ivsize, GFP_ATOMIC,
-				dev_to_node(&vcrypto->vdev->dev));
-	if (!iv) {
-		err = -ENOMEM;
-		goto free;
-	}
+	iv = vc_sym_req->iv;
 	memcpy(iv, req->iv, ivsize);
 	if (!vc_sym_req->encrypt)
 		scatterwalk_map_and_copy(req->iv, req->src,
@@ -416,7 +411,6 @@ __virtio_crypto_skcipher_do_req(struct virtio_crypto_sym_request *vc_sym_req,
 
 	sg_init_one(&iv_sg, iv, ivsize);
 	sgs[num_out++] = &iv_sg;
-	vc_sym_req->iv = iv;
 
 	/* Source data */
 	for (sg = req->src; src_nents; sg = sg_next(sg), src_nents--)
@@ -438,12 +432,10 @@ __virtio_crypto_skcipher_do_req(struct virtio_crypto_sym_request *vc_sym_req,
 	virtqueue_kick(data_vq->vq);
 	spin_unlock_irqrestore(&data_vq->lock, flags);
 	if (unlikely(err < 0))
-		goto free_iv;
+		goto free;
 
 	return 0;
 
-free_iv:
-	kfree_sensitive(iv);
 free:
 	kfree(sgs);
 	return err;
@@ -501,8 +493,10 @@ static int virtio_crypto_skcipher_init(struct crypto_skcipher *tfm)
 {
 	struct virtio_crypto_skcipher_ctx *ctx = crypto_skcipher_ctx(tfm);
 	struct skcipher_alg *alg = crypto_skcipher_alg(tfm);
+	int size;
 
-	crypto_skcipher_set_reqsize(tfm, sizeof(struct virtio_crypto_sym_request));
+	size = sizeof(struct virtio_crypto_sym_request) + crypto_skcipher_ivsize(tfm);
+	crypto_skcipher_set_reqsize(tfm, size);
 	ctx->alg = container_of(alg, struct virtio_crypto_algo, algo.base);
 
 	return 0;
@@ -552,7 +546,7 @@ static void virtio_crypto_skcipher_finalize_req(
 		scatterwalk_map_and_copy(req->iv, req->dst,
 					 req->cryptlen - ivsize,
 					 ivsize, 0);
-	kfree_sensitive(vc_sym_req->iv);
+	memzero_explicit(vc_sym_req->iv, ivsize);
 	virtcrypto_clear_request(&vc_sym_req->base);
 
 	crypto_finalize_skcipher_request(vc_sym_req->base.dataq->engine,
-- 
2.39.3