Re: [PATCH net v2 3/3] selftests: net: tun: test outer protocol of UDP tunnel GSO packets

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Eric Dumazet wrote:
> Add tests writing single 4in4 Geneve GSO frames to tun devices with
> UDP tunnel offloads enabled.
> 
> tun_vnet_udptnl_proto uses a tap device:
> 
> - outer_proto_ok: an outer IPv4 header, with or without an 802.1Q tag,
>   is accepted.
> - outer_proto_bad: an outer ethertype that does not match the declared
>   tunnel type (IPv6 on an IPv4 tunnel, or NSH, with or without a VLAN
>   tag) is rejected with EINVAL.
> 
> tun_vnet_udptnl_proto_l3 uses an IFF_TUN device with a tun_pi header,
> so skb->protocol comes from userspace and there is no Ethernet header.
> The outer IPv4 header carries options, as virtio_net_hdr_tnl_to_skb()
> expects room for an Ethernet header before the outer transport header.
> 
> - outer_proto_ok: tun_pi and the frame agree on IPv4, accepted.
> - outer_proto_bad: tun_pi claims IPv6, or the IP version of the frame
>   is not 4 while tun_pi claims IPv4: rejected with EINVAL.
> 
> Without the first patch of this series, both outer_proto_bad tests fail
> because the kernel accepts the frames.
> 
> Signed-off-by: Eric Dumazet <edumazet@kernel.org>

Reviewed-by: Willem de Bruijn <willemb@google.com>