Re: [PATCH v2 net-next 0/2] net/sched: support tunnel options in cls_flower and act_tunnel_key

David Miller
2017-09-29T10:51:44Z

From: Simon Horman <simon.horman@netronome.com>
Date: Wed, 27 Sep 2017 10:16:32 +0200

> 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 really worry about this.

These metadata option blobs are internal kernel datastructure which we
could change at any point in time. They are not exported to
userspace as a UAPI.

It's kinda OK for eBPF programs to access this stuff since they are
expected to cope with changes to internal data-structures.

But for anything user facing, this really doesn't work.