The ebtables brouting chain, traversed through the call
br_should_route_hook(), can alter a packet. The redirect target
does this, f.e., to change the MAC destination.

Bart discovered this and proposed a patch; this is a revised version.
This version cleans up the handle_bridge code in net/core/dev.c as well
as getting rid of extra rcu_read_lock and only does the br_port checking
once.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@redhat.com>