ipfw and ipsec processing order for outgoing packets wrong

[Joost Bekkers]

On Sat, Oct 30, 2004 at 09:27:50AM +0300, Ari Suutari wrote:
> Hi,
> 
> I noticed that processing order of ipsec and ipfw (pfil_hook) is not
> correct for outgoing packets. Currently, ipsec processing is done first,
> which makes packets to go through without firewall inspection.
> This might be a security problem for someone, but at least it
> breaks stateful rule handling.
> 
> My test setup is (all freebsd 5.3-rc1 machines):
> 
> freebsd laptop <-> ipsec tunnel <->freebsd server
> 
> When server sends packet to laptop, it now goes like this:
> 
> ip_output -> ipsec -> ip_output -> ipfw -> network
> 
> It should go like this:
> 
> ip_output -> ipfw -> ipsec -> ip_output -> ipfw -> network
> 
> I think that this could be fixed by just moving pfil_hook
> processing in ip_output before ipsec processing.
> 

I've been pondering the same issue and am currently running 5.3-R modified in the
way you've described. (diff at http://jodocus.org/ipsec-pfil.diff I'm not an
experienced kernel-hacker, so use at own risk) 

For IPSEC this also means that the resulting ESP and AH packets don't traverse the
firewall when leaving the system. (at least if I read the code correctly; not tested)

With FAST_IPSEC both the original and the resulting ESP/AH packets traverse the
firewall.

In my case I also stumbled on a nice FAST_IPSEC feature where the decoded packets
seemed to arrive through the corresponding gif* interface. (with tunnel-mode ipsec)


-- 
greetz Joost
joost at jodocus.org