Date:   Wed, 11 Nov 2020 20:37:28 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org,
        razor@...ckwall.org, jeremy@...zel.net
Subject: [PATCH net-next,v3 0/9] netfilter: flowtable bridge and vlan enhancements

Hi,

The following patchset augments the Netfilter flowtable fastpath [1] to
support for network topologies that combine IP forwarding, bridge and
VLAN devices.

A typical scenario that can benefit from this infrastructure is composed
of several VMs connected to bridge ports where the bridge master device
'br0' has an IP address. A DHCP server is also assumed to be running to
provide connectivity to the VMs. The VMs reach the Internet through
'br0' as default gateway, which makes the packet enter the IP forwarding
path. Then, netfilter is used to NAT the packets before they leave
through the wan device.

Something like this:

                       fast path
                .------------------------.
               /                          \
               |           IP forwarding   |
               |          /             \  .
               |       br0               eth0
               .       / \
               -- veth1  veth2
                   .
                   .
                   .
                 eth0
           ab:cd:ef:ab:cd:ef
                  VM

The idea is to accelerate forwarding by building a fast path that takes
packets from the ingress path of the bridge port and place them in the
egress path of the wan device (and vice versa). Hence, skipping the
classic bridge and IP stack paths.

This patchset is composed of:

Patch #1 adds a placeholder for the hash calculation, instead of using
	 the dir field. Changes in v3: this patch is new.

Patch #2 adds the transmit path type field to the flow tuple. Two transmit
         paths are supported so far: the neighbour and the xfrm transmit
         paths. This patch comes in preparation to add a new direct ethernet
         transmit path (see patch #7).

	 Changes in v3: I have simplified xmit path type logic.

Patch #3 adds dev_fill_forward_path() and .ndo_fill_forward_path() to
         netdev_ops. This new function describes the list of netdevice hops
         to reach a given destination MAC address in the local network topology,
         e.g.
                           IP forwarding
                          /             \
                       br0              eth0
                       / \
                   veth1 veth2
                    .
                    .
                    .
                   eth0
             ab:cd:ef:ab:cd:ef

          where veth1 and veth2 are bridge ports and eth0 provides Internet
          connectivity. eth0 is the interface in the VM which is connected to
          the veth1 bridge port. Then, for packets going to br0 whose
          destination MAC address is ab:cd:ef:ab:cd:ef, dev_fill_forward_path()
          provides the following path: br0 -> veth1.

Patch #4 adds .ndo_fill_forward_path for VLAN devices, which provides the next
         device hop via vlan->real_dev. This annotates the VLAN id and protocol.
	 This is useful to know what VLAN headers are expected from the ingress
	 device. This also provides information regarding the VLAN headers
	 to be pushed in the egress path.

Patch #5 adds .ndo_fill_forward_path for bridge devices, which allows to make
         lookups to the FDB to locate the next device hop (bridge port) in the
	 forwarding path.

	 Changes in v3: use READ_ONCE() as requested by Nikolay Aleksandrov.

Patch #6 updates the flowtable to use the dev_fill_forward_path()
         infrastructure to obtain the ingress device in the fastpath.

	 Changes in v3: If user specifies:

                devices = { br0, veth1 }
                            ^^^

         then, this still works and the fastpath is only created
         between br0 and veth1 using the neighbour path. Thus, classic
	 bridge path is exercised. If user specifies:

                devices = { veth0, veth1 }
                            ^^^^^

         then, dev_forward_path() provides an earlier ingress fastpath
	 ie. flowtable lookups for incoming packets happen in veth0 instead
	 of br0).

	There is fallback to use the neighbour path if:

	- dev_fill_forward_path() finds no real ingress device.
	- the ingress device that is obtained is not part of the flowtable
	  devices.
	- this route has a xfrm policy.

Patch #7 updates the flowtable to use dev_fill_forward_path() to obtain the
	 egress device in the forwarding path. This also adds the direct
	 ethernet transmit path, which pushes the ethernet header to the
	 packet and send it through dev_queue_xmit(). This patch adds
	 support for the bridge, so bridge ports use this direct xmit path.

         Changes in v3:
	- add the direct xmit path and use it for bridge devices type,
	  formely in v2 this came as two separated patches.
	- use union so it's either the direct xmit info or the IP dst
	  that is stored in the flow tuple to reduce memory footprint.
	- use dev_hard_header() in the direct xmit path to simplify VLAN
	  support coming patch #8.

Patch #8 adds ingress VLAN support (up to 2 VLAN tags, QinQ). The VLAN
	 information is also provided by dev_fill_forward_path(). Store the
	 VLAN id and protocol in the flow tuple for hash lookups. The VLAN
	 support in the xmit path is achieved by annotating the first vlan
	 device found in the xmit path and by calling dev_hard_header()
	 (previous patch #7) before dev_queue_xmit().

	Changes in v3:
	- Use VLAN device xmit path instead of manually pushing the
	  VLAN headers from the flowtable datapath to reuse the existing
	  device xmit infrastructure.

Patch #9 extends nft_flowtable.sh selftest: This is adding a test to
	 cover bridge and vlan support coming in this patchset.

	Changes in v3: this patch is new.

= Performance numbers

My testbed environment consists of three containers:

  192.168.20.2     .20.1     .10.1   10.141.10.2
         veth0       veth0 veth1      veth0
	ns1 <---------> nsr1 <--------> ns2
                            SNAT
     iperf -c	                       iperf -s

where nsr1 is used for forwarding. There is a bridge device br0 in nsr1,
veth0 is a port of br0. SNAT is performed on the veth1 device of nsr1.

- ns2 runs iperf -s
- ns1 runs iperf -c 10.141.10.2 -n 100G

My results are:

- Baseline (no flowtable, classic forwarding path + netfilter): ~16 Gbit/s
- Fastpath (with flowtable, this patchset): ~25 Gbit/s

This is an improvement of ~50% compared to baseline. My testbed is not
optimized, there are a few of instrumentation toggles turned on in my
kernel for debugging and this equipment is aging a bit.

Please apply, thanks.

Pablo Neira Ayuso (9):
  netfilter: flowtable: add hash offset field to tuple
  netfilter: flowtable: add xmit path types
  net: resolve forwarding path from virtual netdevice and HW destination address
  net: 8021q: resolve forwarding path for vlan devices
  bridge: resolve forwarding path for bridge devices
  netfilter: flowtable: use dev_fill_forward_path() to obtain ingress device
  netfilter: flowtable: use dev_fill_forward_path() to obtain egress device
  netfilter: flowtable: add vlan support
  selftests: netfilter: flowtable bridge and VLAN support

 include/linux/netdevice.h                     |  35 +++
 include/net/netfilter/nf_flow_table.h         |  43 +++-
 net/8021q/vlan_dev.c                          |  15 ++
 net/bridge/br_device.c                        |  24 +++
 net/core/dev.c                                |  31 +++
 net/netfilter/nf_flow_table_core.c            |  51 +++--
 net/netfilter/nf_flow_table_ip.c              | 200 ++++++++++++++----
 net/netfilter/nft_flow_offload.c              | 159 +++++++++++++-
 .../selftests/netfilter/nft_flowtable.sh      |  82 +++++++
 9 files changed, 580 insertions(+), 60 deletions(-)

-- 
2.20.1

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