Commit 065af355 authored Aug 01, 2019 by Jesper Dangaard Brouer Committed by David S. Miller Aug 05, 2019

net: fix bpf_xdp_adjust_head regression for generic-XDP

When generic-XDP was moved to a later processing step by commit
458bf2f2 ("net: core: support XDP generic on stacked devices.")
a regression was introduced when using bpf_xdp_adjust_head.

The issue is that after this commit the skb->network_header is now
changed prior to calling generic XDP and not after. Thus, if the header
is changed by XDP (via bpf_xdp_adjust_head), then skb->network_header
also need to be updated again. Fix by calling skb_reset_network_header().

Fixes: 458bf2f2 ("net: core: support XDP generic on stacked devices.")
Reported-by: Brandon Cazander <brandon.cazander@multapplied.net>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 13978d1e

net/core/dev.c

+10 −5

Original line number	Diff line number	Diff line
		@@ -4374,12 +4374,17 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb,

		act = bpf_prog_run_xdp(xdp_prog, xdp);

		/* check if bpf_xdp_adjust_head was used */
		off = xdp->data - orig_data;
		if (off) {
		if (off > 0)
		__skb_pull(skb, off);
		else if (off < 0)
		__skb_push(skb, -off);

		skb->mac_header += off;
		skb_reset_network_header(skb);
		}

		/* check if bpf_xdp_adjust_tail was used. it can only "shrink"
		* pckt.

Admin message