[ovs-dev] [PATCH] datapath-windows: check source port during tunnel Tx

Ben Pfaff blp at nicira.com
Wed Aug 13 21:12:02 UTC 2014

On Tue, Aug 12, 2014 at 10:59:29PM -0700, Nithin Raju wrote:
> In the Windows datapath, Tx tunneling functionality is implemented by checking
> if the outport in the action is a tunnel port. If so, the packet is
> encapsulated and sent out on the PIF bridge for as second flow lookup.
> Basically, we don't use the hypervisor's IP stack to send out a packet, and
> short circuit the path ourselves. On the PIF bridge, the source port of the
> encapsulated packet is the VTEP port ie. the internal port.
> If a Tunneling port is added to the PIF bridge (a possible misconfiguration),
> where the VTEP(internal) port and the external port (physical NIC) also reside,
> a flooding action can cause a loop, by re-injecting the packet on the same PIF
> bridge which again floods to the tunnel port.
> In this change, we break the loop by encapsulating packets only if they are
> sent out by a VIF or if they originate from userspace ie. userspace generated.
> We make use of the input port attribute in the packet execute ioctl.
> This change is based off of the legacy datapath interface published in
> OvsPub.h. This interface has a input port field in the packet execute ioctl.
> I looked in dpif-linux.c that uses the netlink based datapath interface and
> even in that case, we do add the the source port in:
>     dpif_linux_encode_execute() -> odp_key_from_pkt_metadata().
> So, this fix is applicable when we adopt the netlink based datapath interface
> as well.
> The Rx side of OvsDetectTunnelPkt() has only documentation updates. The fix is
> on the Tx side.
> Validation (using dpif-windows.c):
> - Was able to perform VTEP <-> VTEP ping with the configuration posted in the
> issue.
> - Was able to perform VIF <-> VIF ping when the setup was configured correctly.
> Signed-off-by: Nithin Raju <nithin at vmware.com>
> Reported-by: Alin Serdean <aserdean at cloudbasesolutions.com>
> Reported-at: https://github.com/openvswitch/ovs-issues/issues/20

Applied to master, thanks!

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