netdev - Re: [PATCH net 3/3] gre: receive also TEB packets for lwtunnels

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Date:	Fri, 22 Apr 2016 14:07:01 -0700
From:	pravin shelar <pshelar@....org>
To:	Jiri Benc <jbenc@...hat.com>
Cc:	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	Pravin B Shelar <pshelar@...ira.com>,
	Thomas Graf <tgraf@...g.ch>,
	Simon Horman <simon.horman@...ronome.com>
Subject: Re: [PATCH net 3/3] gre: receive also TEB packets for lwtunnels

On Fri, Apr 22, 2016 at 10:44 AM, Jiri Benc <jbenc@...hat.com> wrote:
> For ipgre interfaces in collect metadata mode, receive also traffic with
> encapsulated Ethernet headers. The lwtunnel users are supposed to sort this
> out correctly. This allows to have mixed Ethernet + L3-only traffic on the
> same lwtunnel interface.
>
How user is suppose to sort out the type of packet? whether it is L2 or L3.

> To keep backwards compatibility and prevent any surprises, gretap interfaces
> have priority in receiving packets with Ethernet headers.
>
> Signed-off-by: Jiri Benc <jbenc@...hat.com>
> ---
>  include/net/ip_tunnels.h |  1 +
>  net/ipv4/ip_gre.c        | 34 +++++++++++++++++++++++++---------
>  2 files changed, 26 insertions(+), 9 deletions(-)
>

...

> +
> +static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi)
> +{
> +       struct net *net = dev_net(skb->dev);
> +       struct ip_tunnel_net *itn;
> +       int res;
> +
> +       if (tpi->proto == htons(ETH_P_TEB))
> +               itn = net_generic(net, gre_tap_net_id);
> +       else
> +               itn = net_generic(net, ipgre_net_id);
> +
> +       res = __ipgre_rcv(skb, tpi, itn);
> +       if (res == PACKET_NEXT && tpi->proto == htons(ETH_P_TEB)) {
> +               /* ipgre tunnels in collect metadata mode should receive
> +                * also ETH_P_TEB traffic
> +                */
> +               itn = net_generic(net, ipgre_net_id);
> +               res = __ipgre_rcv(skb, tpi, int);

Is it fine to receive L2 packet over L3 device?
At least ip_tunnel_rcv() is not ready to handle such packet.