Re: [PATCH 1/4] veth: move loopback logic to common location

Eric W. Biederman wrote:

Patrick McHardy [off-list ref] writes:

quoted

In the layered case (macvlan -> eth0) its common behaviour to
keep the mark however. But in case of different namespaces,
I think macvlan should also clear the mark on the dev_queue_xmit()
path since this is just a shortcut to looping the packets
through veth. In fact probably both of them should also clear
skb->priority so other namespaces don't accidentally misclassify
packets.

That is why I pushed for what is becoming dev_forward_skb.  So that
we have one place where we can make all of those tweaks.  It seems
like in every review we find another field that should be cleared/handled
specially.

I don't quite follow what you intend with dev_queue_xmit when the macvlan
is in one namespace and the real physical device is in another.  Are
you mentioning that the packet classifier runs in the namespace where
the primary device lives with packets from a different namespace?

Exactly. And I think we should make sure that the namespace of
the macvlan device can't (deliberately or accidentally) cause
misclassification.