From: Jesper Dangaard Brouer Date: Thu, 1 Aug 2019 18:00:31 +0000 (+0200) Subject: net: fix bpf_xdp_adjust_head regression for generic-XDP X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=065af355470519bd184019a93ac579f22b036045;p=linux.git net: fix bpf_xdp_adjust_head regression for generic-XDP When generic-XDP was moved to a later processing step by commit 458bf2f224f0 ("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: 458bf2f224f0 ("net: core: support XDP generic on stacked devices.") Reported-by: Brandon Cazander Signed-off-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- diff --git a/net/core/dev.c b/net/core/dev.c index 2f341b8508456..0891f499c1bb7 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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 > 0) - __skb_pull(skb, off); - else if (off < 0) - __skb_push(skb, -off); - skb->mac_header += off; + 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.