ipv4: Set skb->protocol properly for local output

ipv4: Set skb->protocol properly for local output

When xfrm is applied to TSO/GSO packets, it follows this path:

    xfrm_output() -> xfrm_output_gso() -> skb_gso_segment()

where skb_gso_segment() relies on skb->protocol to function properly.

This patch sets skb->protocol to ETH_P_IP before dst_output() is called,
fixing a bug where GSO packets sent through a sit tunnel are dropped
when xfrm is involved.

Cc: [email protected]
Signed-off-by: Eli Cooper <[email protected]>
Signed-off-by: David S. Miller <[email protected]>