From: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
[ Upstream commit 065af355470519bd184019a93ac579f22b036045 ]
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 <brandon.cazander@xxxxxxxxxxxxxxx>
Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/dev.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4382,12 +4382,17 @@ static u32 netif_receive_generic_xdp(str
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.
