kern/140512: pf doesn't block udp packets on multicast addresses

[Stephane D'Alu]

>Number:         140512
>Category:       kern
>Synopsis:       pf doesn't block udp packets on multicast addresses
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Nov 12 21:20:01 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Stephane D'Alu
>Release:        8.0-RC2
>Organization:
>Environment:
FreeBSD incal.sdalu.com 8.0-RC2 FreeBSD 8.0-RC2 #14: Mon Nov  9 23:14:33 CET 2009     root at incal.sdalu.com:/usr/obj/usr/src/sys/INCAL  amd64

>Description:
for udp firewall rule is somewhat equivalent to (full rules available on request)

set skip on lo0
scrub in all
block in log all
pass out all
pass in proto { tcp, udp } from any to net0 port domain
pass in proto udp from any to net0 port { isakmp, 4500 }

When sniffing net0 with tcpdump the following packet will show up:

ks358229.kimsufi.com.mdns > 224.0.0.251.mdns
rbx-48-m2.routers.ovh.net.1985 > ALL-ROUTERS.MCAST.NET.1985
pastel-pink.feralhosting.com.6771 > 239.192.152.143.6771
ks358206.kimsufi.com.50914 > 239.255.255.250.1900

They all seems to be using multicast addresses
 (Dont know if broadcast or tcp have the same issue)
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: