Linux Ethernet Bridging - Mar 2017 - [Bridge] [PATCH net] bridge: ebtables: fix reception of frames DNAT-ed to bridge device

On Wed, Mar 15, 2017 at 03:27:20PM +0100, Linus L?ssing
wrote:
> On Wed, Mar 15, 2017 at 11:42:11AM +0100, Pablo Neira Ayuso wrote:
> > I'm missing then why redirect is not then just enough for Linus
usecase.
> 
> For my usecase, the MAC address is configured by the user from a
> Web-UI. It may or may not be the one from the bridge device.
> 
> Besides, found it counter intuitive that DNAT did not work here
> and took me some time to find out why. At least I didn't read about
> any such known limitations of the dnat target in the ebtables
> manpage.
Could you update ebtables dnat to check if the ethernet address
matches the one of the input bridge interface, so we mangle the
->pkt_type accordingly from there, instead of doing this from the
core?

On Wed, Mar 15, 2017 at 07:15:39PM +0100, Pablo Neira Ayuso
wrote:
> Could you update ebtables dnat to check if the ethernet address
> matches the one of the input bridge interface, so we mangle the
> ->pkt_type accordingly from there, instead of doing this from the
> core?
Actually, that was the approach I thought about and went for first
(and it would probably work for me). Just checking against the
bridge device's net_device::dev_addr.

I scratched it though, as I was afraid that the issue might still
exist for people using some other upper device on top of the bridge
device. For instance, macvlan? And iterating over the
net_device::dev_addrs list seemed too costly for fast path to me.