Hi Thomas,

On 29.11.2016 14:21, Thomas Graf wrote:

This series implements BPF program invocation from dst entries via the
lightweight tunnels infrastructure. The BPF program can be attached to
lwtunnel_input(), lwtunnel_output() or lwtunnel_xmit() and see an L3
skb as context. Programs attached to input and output are read-only.
Programs attached to lwtunnel_xmit() can modify and redirect, push headers
and redirect packets.

The facility can be used to:
 - Collect statistics and generate sampling data for a subset of traffic
   based on the dst utilized by the packet thus allowing to extend the
   existing realms.
 - Apply additional per route/dst filters to prohibit certain outgoing
   or incoming packets based on BPF filters. In particular, this allows
   to maintain per dst custom state across multiple packets in BPF maps
   and apply filters based on statistics and behaviour observed over time.
 - Attachment of L2 headers at transmit where resolving the L2 address
   is not required.
 - Possibly many more.

Did you look at the cgroup based hooks which were added recently in
ip_finish_output for cgroup ebpf support and in general the cgroup bpf
subsystem. Does some of this solve the problem for you already? Would be
interesting to hear your opinion on that.

Thanks,
Hannes