On Fri, Feb 05, 2021 at 02:42:55PM -0800, Florian Fainelli wrote: > How does the mirred action deal with that case? How does it know that > packets delivered to the DSA master should be sent towards a foreign > address, do I need to set-up two mirred rules? One that set-ups the > filter on say sw0p0 to redirect egress to eth0 (DSA master) and another > one to ingress filter on eth0 and egress mirror to eth1 (USB ethernet > dongle)?
[ I should have posted this as RFC, somebody asked me if it's possible, I only tested ingress mirroring, saw something come out, and posted this. I didn't even study act_mirred.c to see why I got anything at all ] For ingress mirroring there should be nothing special about the mirror packets, it's just more traffic in the ingress data path where the qdisc hook already exists. For egress mirroring I don't think there's really any way for the mirred action to take over the packets from what is basically the ingress qdisc and into the egress qdisc of the DSA interface such that they will be redirected to the selected mirror. I hadn't even thought about egress mirroring. I suppose with more API, we could have DSA do introspection into the frame header, see it's an egress-mirrored packet, and inject it into the egress qdisc of the net device instead of doing netif_rx. The idea with 2 mirrors might work however it's not amazing and I was thinking that if we bother to do something at all, we could as well try to think it through and come up with something that's seamless for the user.
