From 6870de435b90c083ae0f3f7f341287976ef56f03 Mon Sep 17 00:00:00 2001 From: "Nikita V. Shirokov" Date: Tue, 17 Apr 2018 21:42:20 -0700 Subject: [PATCH] bpf: make virtio compatible w/ bpf_xdp_adjust_tail w/ bpf_xdp_adjust_tail helper xdp's data_end pointer could be changed as well (only "decrease" of pointer's location is going to be supported). changing of this pointer will change packet's size. for virtio driver we need to adjust XDP_PASS handling by recalculating length of the packet if it was passed to the TCP/IP stack Reviewed-by: Jason Wang Signed-off-by: Nikita V. Shirokov Signed-off-by: Daniel Borkmann --- drivers/net/virtio_net.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 01694e26f03e..779a4f798522 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -606,6 +606,7 @@ static struct sk_buff *receive_small(struct net_device *dev, case XDP_PASS: /* Recalculate length in case bpf program changed it */ delta = orig_data - xdp.data; + len = xdp.data_end - xdp.data; break; case XDP_TX: xdpf = convert_to_xdp_frame(&xdp); @@ -642,7 +643,7 @@ static struct sk_buff *receive_small(struct net_device *dev, goto err; } skb_reserve(skb, headroom - delta); - skb_put(skb, len + delta); + skb_put(skb, len); if (!delta) { buf += header_offset; memcpy(skb_vnet_hdr(skb), buf, vi->hdr_len); @@ -757,6 +758,10 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, offset = xdp.data - page_address(xdp_page) - vi->hdr_len; + /* recalculate len if xdp.data or xdp.data_end were + * adjusted + */ + len = xdp.data_end - xdp.data; /* We can only create skb based on xdp_page. */ if (unlikely(xdp_page != page)) { rcu_read_unlock(); -- 2.30.2