Commit 8fb58f1e authored Apr 17, 2018 by Nikita V. Shirokov Committed by Daniel Borkmann Apr 18, 2018

bpf: make tun 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 tun driver we need to adjust XDP_PASS handling by recalculating
length of the packet if it was passed to the TCP/IP stack
(in case if after xdp's prog run data_end pointer was adjusted)

Reviewed-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

parent 5a6a22e3

drivers/net/tun.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1696,6 +1696,7 @@ static struct sk_buff tun_build_skb(struct tun_struct tun,
		return NULL;
		case XDP_PASS:
		delta = orig_data - xdp.data;
		len = xdp.data_end - xdp.data;
		break;
		default:
		bpf_warn_invalid_xdp_action(act);
		@@ -1716,7 +1717,7 @@ static struct sk_buff tun_build_skb(struct tun_struct tun,
		}

		skb_reserve(skb, pad - delta);
		skb_put(skb, len + delta);
		skb_put(skb, len);
		get_page(alloc_frag->page);
		alloc_frag->offset += buflen;

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