netdev - Re: [oss-drivers] Re: [PATCH/RFC net-next 2/2] net/sched: allow flower to match tunnel options

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Date:   Wed, 13 Sep 2017 15:29:28 +0200
From:   Simon Horman <simon.horman@...ronome.com>
To:     Or Gerlitz <gerlitz.or@...il.com>
Cc:     Jiri Pirko <jiri@...lanox.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Linux Netdev List <netdev@...r.kernel.org>,
        oss-drivers@...ronome.com
Subject: Re: [oss-drivers] Re: [PATCH/RFC net-next 2/2] net/sched: allow
 flower to match tunnel options

On Wed, Sep 13, 2017 at 03:38:01PM +0300, Or Gerlitz wrote:
> On Wed, Sep 13, 2017 at 2:59 PM, Simon Horman
> <simon.horman@...ronome.com> wrote:
> > On Wed, Sep 13, 2017 at 01:03:43PM +0300, Or Gerlitz wrote:
> >> On Wed, Sep 13, 2017 at 12:25 PM, Simon Horman
> >> <simon.horman@...ronome.com> wrote:
> >> > On Tue, Sep 12, 2017 at 11:23:55PM +0300, Or Gerlitz wrote:
> >> >> On Tue, Sep 12, 2017 at 5:20 PM, Simon Horman
> >> >> <simon.horman@...ronome.com> wrote:
> >> >> > Allow matching on options in tunnel headers.
> >> >> > This makes use of existing tunnel metadata support.
> >> >>
> >> >> Simon,
> >> >>
> >> >> This patch is about matching on tunnel options, right? but
> >> >>
> >> >> > Options are a bytestring of up to 256 bytes.
> >> >> > Tunnel implementations may support less or more options,
> >> >> > or no options at all.
> >> >> >
> >> >> >  # ip link add name geneve0 type geneve dstport 0 external
> >> >> >  # tc qdisc add dev eth0 ingress
> >> >> >  # tc qdisc del dev eth0 ingress; tc qdisc add dev eth0 ingress
> >> >> >  # tc filter add dev eth0 protocol ip parent ffff: \
> >> >> >      flower indev eth0 \
> >> >> >         ip_proto udp \
> >> >> >         action tunnel_key \
> >> >> >             set src_ip 10.0.99.192 \
> >> >> >             dst_ip 10.0.99.193 \
> >> >> >             dst_port 4789 \
> >> >> >             id 11 \
> >> >> >             opts 0102800100800022 \
> >> >> >     action mirred egress redirect dev geneve0
> >> >>
> >> >> the example here is on how to use tunnel options in the tunnel set key actions..
> >> >>
> >> >> And the other way around in the other patch... the patch is about the
> >> >> tunnel key set action and the example shows how to match that in
> >> >> flower... I guess you want to swap the relevant of the change log.
> >> >
> >> > Yes, it seems so. Sorry about that.
> >>
> >> no worries, you can do the swap, but before that
> >>
> >> >> Anyway, is there any human readable/understandable representation of
> >> >> these options? e.g what does 0102800100800022 means for geneve?
> >>
> >> > Thanks, I had not thought of that. My feeling is that could
> >> > be added to the tc tool as follow-up work.
> >>
> >> could you spend few words on the nature of these options now when we review
> >> the kernel patches? I guess this is somehow related to protocols such
> >> as geneve and vxlan-gpe  -- it would be good if you elaborate on that
> >> a bit, does
> >> the kernel does any usage with these options beyond matching on them or stiching
> >> them to packet headers?
> >
> > This feature is to be used in conjunction with tunnels in collect metadata
> > (external) mode. As I understand it there are three tunnel netdevs that use
> > options metadata in the kernel at this time.
> >
> > * Geneve
> >
> >   In the case of Geneve options are TLVs[1]. My reading is that in collect
> >   metadata mode the kernel does not appear to do anything other than pass
> >   them around as a bytestring.
> >
> >   [1] https://tools.ietf.org/html/draft-ietf-nvo3-geneve-05#section-3.5
> >
> > * VXLAN-GBP
> >
> >   In the case of VXLAN-GBP on RX in collect metadata mode options are used
> >   to carry information parsed in vxlan_parse_gbp_hdr() from the VXLAN Group
> >   Based Policy Extension[2]. On RX the options data is used to create an
> >   extension (header) by vxlan_build_gbp_hdr().
> >
> >   [2] https://tools.ietf.org/html/draft-smith-vxlan-group-policy-03#section-2.1
> >
> > * ERSPAN (GRE)
> >
> >   In the case of ERSPAN, which is a variant of GRE, on RX in collect
> >   metadata mode options are used to carry the index parsed from the ERSPAN
> >   Type II feature header[3] in erspan_rcv().  The converse is true on TX
> >   and is handled by erspan_fb_xmit().
> >
> >   [3] https://tools.ietf.org/html/draft-foschiano-erspan-03#section-4.2
> >
> > Users of options:
> >
> > * There are eBPF hooks to allow getting on and setting tunnel metadata:
> >   bpf_skb_set_tunnel_opt, bpf_skb_get_tunnel_opt.
> >
> > * Open vSwitch is able to match and set Geneve and VXLAN-GBP options.
> >
> > Neither of the above appear to assume any structure for the data.
> >
> > I hope the above is the kind of information you are after.
> 
> yeah, this helps, do we expect HW offloads to be able to work with
> these options? e.g place/match on packets
> or even do something beyond that?

Perhaps unsurprisingly given my posting I would like to offload
"place/match" of options. I do not currently have any plans beyond that
and my crystal ball broke some time ago.