# Re: \[PATCH net v3 5/8\] selftests: net: tun: test outer protocol of UDP tunnel GSO packets

- From: sashiko-bot@kernel.org
- Date: 2026-11-06 08:16:43 
- List: virtualization
- Page: https://ratatoskr.run/virtualization/2026/11/17876508
- Thread: https://ratatoskr.run/virtualization/2026/11/17870111/t.md

```text
> 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.
> 
> Reviewed-by: Willem de Bruijn <willemb@google.com>
> Signed-off-by: Eric Dumazet <edumazet@kernel.org>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261105115715.1466924-1-edumazet@kernel.org?part=5

```