net: fix generic XDP to handle if eth header was mangled
XDP can modify (and resize) the Ethernet header in the packet. There is a bug in generic-XDP, because skb->protocol and skb->pkt_type are setup before reaching (netif_receive_)generic_xdp. This bug was hit when XDP were popping VLAN headers (changing eth->h_proto), as skb->protocol still contains VLAN-indication (ETH_P_8021Q) causing invocation of skb_vlan_untag(skb), which corrupt the packet (basically popping the VLAN again). This patch catch if XDP changed eth header in such a way, that SKB fields needs to be updated. V2: on request from Song Liu, use ETH_HLEN instead of mac_len, in __skb_push() as eth_type_trans() use ETH_HLEN in paired skb_pull_inline(). Fixes: d4455169 ("net: xdp: support xdp generic on virtual devices") Signed-off-by:Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by:
Alexei Starovoitov <ast@kernel.org>
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