[PATCH nf-next v3 0/3] Netfilter egress hook

[Lukas Wunner <lukas@wunner.de>]

Introduce a netfilter egress hook to allow filtering outbound AF_PACKETs
such as DHCP and to prepare for in-kernel NAT64/NAT46.

An earlier version of this series was applied by Pablo Neira Ayuso back
in March and subsequently reverted by Daniel Borkmann over performance
concerns.  I've now reworked the series following a discussion between
Daniel and Florian Westphal:

https://lore.kernel.org/netdev/20200318123315.GI979@breakpoint.cc/

Briefly, traffic control and netfilter handling is moved out of the
__dev_queue_xmit() hotpath into a noinline function which is dynamically
patched in using a static_key.  In that function, each of tc and nft are
patched in with additional static_keys.

Thus, if neither tc nor nft is used, performance improves compared to
the status quo (see measurements in patch [3/3]).  However if tc is
used, performance degrades a little due to the "noinline", the additional
outer static key and the added netfilter code.  That's kind of a bummer.
If anyone has ideas how to mitigate this performance degradation, please
come forward.

To test the new netfilter egress hook, apply this nft patch to add rules
from user space:

https://lore.kernel.org/netfilter-devel/d6b6896fdd8408e4ddbd66ab524709e5cf82ea32.1583929080.git.lukas@wunner.de/

Thanks!

Lukas Wunner (3):
  netfilter: Rename ingress hook include file
  netfilter: Generalize ingress hook
  netfilter: Introduce egress hook

 include/linux/netdevice.h         |   8 +++
 include/linux/netfilter_ingress.h |  58 -----------------
 include/linux/netfilter_netdev.h  | 102 ++++++++++++++++++++++++++++++
 include/linux/rtnetlink.h         |   2 +-
 include/uapi/linux/netfilter.h    |   1 +
 net/core/dev.c                    |  56 +++++++++++++---
 net/netfilter/Kconfig             |   8 +++
 net/netfilter/core.c              |  24 +++++--
 net/netfilter/nft_chain_filter.c  |   4 +-
 net/sched/Kconfig                 |   3 +
 10 files changed, 194 insertions(+), 72 deletions(-)
 delete mode 100644 include/linux/netfilter_ingress.h
 create mode 100644 include/linux/netfilter_netdev.h

-- 
2.27.0