Add ipfw hooks to ether_demux() and ether_output_frame().

Ipfw processing of frames at layer 2 can be enabled by the sysctl variable

	net.link.ether.ipfw=1

Consider this feature experimental, because right now, the firewall
is invoked in the places indicated below, and controlled by the
sysctl variables listed on the right.  As a consequence, a packet
can be filtered from 1 to 4 times depending on the path it follows,
which might make a ruleset a bit hard to follow.

I will add an ipfw option to tell if we want a given rule to apply
to ether_demux() and ether_output_frame(), but we have run out of
flags in the struct ip_fw so i need to think a bit on how to implement
this.

		to upper layers
	     |			     |
	     +----------->-----------+
	     ^			     V
	[ip_input]		[ip_output]	net.inet.ip.fw.enable=1
	     |			     |
	     ^			     V
	[ether_demux]      [ether_output_frame]	net.link.ether.ipfw=1
	     |			     |
	     +->- [bdg_forward]-->---+		net.link.ether.bridge_ipfw=1
	     ^			     V
	     |			     |
		 to devices

0 files changed, 0 insertions, 0 deletions