From: Willem de Bruijn <willemdebruijn.ker...@gmail.com>
Date: Tue, 21 Nov 2017 10:22:25 -0500
> From: Willem de Bruijn <will...@google.com>
>
> Tuntap and similar devices can inject GSO packets. Accept type
> VIRTIO_NET_HDR_GSO_UDP, even though not generating UFO natively.
>
> Processes are expected to use feature negotiation such as TUNSETOFFLOAD
> to detect supported offload types and refrain from injecting other
> packets. This process breaks down with live migration: guest kernels
> do not renegotiate flags, so destination hosts need to expose all
> features that the source host does.
>
> Partially revert the UFO removal from 182e0b6b5846~1..d9d30adf5677.
> This patch introduces nearly(*) no new code to simplify verification.
> It brings back verbatim tuntap UFO negotiation, VIRTIO_NET_HDR_GSO_UDP
> insertion and software UFO segmentation.
>
> It does not reinstate protocol stack support, hardware offload
> (NETIF_F_UFO), SKB_GSO_UDP tunneling in SKB_GSO_SOFTWARE or reception
> of VIRTIO_NET_HDR_GSO_UDP packets in tuntap.
>
> To support SKB_GSO_UDP reappearing in the stack, also reinstate
> logic in act_csum and openvswitch. Achieve equivalence with v4.13 HEAD
> by squashing in commit 939912216fa8 ("net: skb_needs_check() removes
> CHECKSUM_UNNECESSARY check for tx.") and reverting commit 8d63bee643f1
> ("net: avoid skb_warn_bad_offload false positives on UFO").
>
> (*) To avoid having to bring back skb_shinfo(skb)->ip6_frag_id,
> ipv6_proxy_select_ident is changed to return a __be32 and this is
> assigned directly to the frag_hdr. Also, SKB_GSO_UDP is inserted
> at the end of the enum to minimize code churn.
...
> Link:
> http://lkml.kernel.org/r/<CAF=yd-luuedul9ywpjd9ykoz0qcjneznpdr6whqz9ngmnf1...@mail.gmail.com>
> Fixes: fb652fdfe837 ("macvlan/macvtap: Remove NETIF_F_UFO advertisement.")
> Reported-by: Michal Kubecek <mkube...@suse.cz>
> Signed-off-by: Willem de Bruijn <will...@google.com>
Applied and queued up for -stable, thanks!
