The xdp program may overwrite the inline virtio header. To ensure the
integrity of the virtio header, it is saved in a data structure that
wraps both the xdp_buff and the header before running the xdp program.
Signed-off-by: Liang Chen <liangchen.li...@gmail.com>
---
drivers/net/virtio_net.c | 43 +++++++++++++++++++++++++++++-----------
1 file changed, 31 insertions(+), 12 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index d7ce4a1011ea..b56828804e5f 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -349,6 +349,11 @@ struct virtio_net_common_hdr {
};
};
+struct virtnet_xdp_buff {
+ struct xdp_buff xdp;
+ struct virtio_net_common_hdr hdr;
+};
+
static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);
static bool is_xdp_frame(void *ptr)
@@ -1199,9 +1204,10 @@ static struct sk_buff *receive_small_xdp(struct
net_device *dev,
unsigned int headroom = vi->hdr_len + header_offset;
struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset;
struct page *page = virt_to_head_page(buf);
+ struct virtnet_xdp_buff virtnet_xdp;
struct page *xdp_page;
+ struct xdp_buff *xdp;
unsigned int buflen;
- struct xdp_buff xdp;
struct sk_buff *skb;
unsigned int metasize = 0;
u32 act;
@@ -1233,17 +1239,23 @@ static struct sk_buff *receive_small_xdp(struct
net_device *dev,
page = xdp_page;
}
- xdp_init_buff(&xdp, buflen, &rq->xdp_rxq);
- xdp_prepare_buff(&xdp, buf + VIRTNET_RX_PAD + vi->hdr_len,
+ xdp = &virtnet_xdp.xdp;
+ xdp_init_buff(xdp, buflen, &rq->xdp_rxq);
+ xdp_prepare_buff(xdp, buf + VIRTNET_RX_PAD + vi->hdr_len,
xdp_headroom, len, true);
- act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats);
+ /* Copy out the virtio header, as it may be overwritten by the
+ * xdp program.
+ */
+ memcpy(&virtnet_xdp.hdr, hdr, vi->hdr_len);
+
+ act = virtnet_xdp_handler(xdp_prog, xdp, dev, xdp_xmit, stats);
switch (act) {
case XDP_PASS:
/* Recalculate length in case bpf program changed it */
- len = xdp.data_end - xdp.data;
- metasize = xdp.data - xdp.data_meta;
+ len = xdp->data_end - xdp->data;
+ metasize = xdp->data - xdp->data_meta;
break;
case XDP_TX:
@@ -1254,7 +1266,7 @@ static struct sk_buff *receive_small_xdp(struct
net_device *dev,
goto err_xdp;
}
- skb = virtnet_build_skb(buf, buflen, xdp.data - buf, len);
+ skb = virtnet_build_skb(buf, buflen, xdp->data - buf, len);
if (unlikely(!skb))
goto err;
@@ -1591,10 +1603,11 @@ static struct sk_buff *receive_mergeable_xdp(struct
net_device *dev,
int num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
struct page *page = virt_to_head_page(buf);
int offset = buf - page_address(page);
+ struct virtnet_xdp_buff virtnet_xdp;
unsigned int xdp_frags_truesz = 0;
struct sk_buff *head_skb;
unsigned int frame_sz;
- struct xdp_buff xdp;
+ struct xdp_buff *xdp;
void *data;
u32 act;
int err;
@@ -1604,16 +1617,22 @@ static struct sk_buff *receive_mergeable_xdp(struct
net_device *dev,
if (unlikely(!data))
goto err_xdp;
- err = virtnet_build_xdp_buff_mrg(dev, vi, rq, &xdp, data, len, frame_sz,
+ xdp = &virtnet_xdp.xdp;
+ err = virtnet_build_xdp_buff_mrg(dev, vi, rq, xdp, data, len, frame_sz,
&num_buf, &xdp_frags_truesz, stats);
if (unlikely(err))
goto err_xdp;
- act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats);
+ /* Copy out the virtio header, as it may be overwritten by the
+ * xdp program.
+ */
+ memcpy(&virtnet_xdp.hdr, hdr, vi->hdr_len);
+
+ act = virtnet_xdp_handler(xdp_prog, xdp, dev, xdp_xmit, stats);
switch (act) {
case XDP_PASS:
- head_skb = build_skb_from_xdp_buff(dev, vi, &xdp,
xdp_frags_truesz);
+ head_skb = build_skb_from_xdp_buff(dev, vi, xdp,
xdp_frags_truesz);
if (unlikely(!head_skb))
break;
return head_skb;
@@ -1626,7 +1645,7 @@ static struct sk_buff *receive_mergeable_xdp(struct
net_device *dev,
break;
}
- put_xdp_frags(&xdp);
+ put_xdp_frags(xdp);
err_xdp:
put_page(page);
--
2.40.1
