svn commit: r281536 - head/sys/netpfil/pf

[Kristof Provost]

On 2015-04-15 15:53:02 (+0300), Gleb Smirnoff <glebius at FreeBSD.org> wrote:
> On Tue, Apr 14, 2015 at 07:07:37PM +0000, Kristof Provost wrote:
> K> Author: kp
> K> Date: Tue Apr 14 19:07:37 2015
> K> New Revision: 281536
> K> URL: https://svnweb.freebsd.org/changeset/base/281536
> K> 
> K> Log:
> K>   pf: Fix forwarding detection
> K>   
> K>   If the direction is not PF_OUT we can never be forwarding. Some input packets
> K>   have rcvif != ifp (looped back packets), which lead us to ip6_forward() inbound
> K>   packets, causing panics.
> K>   
> K>   Equally, we need to ensure that packets were really received and not locally
> K>   generated before trying to ip6_forward() them.
> K>   
> K>   Differential Revision:	https://reviews.freebsd.org/D2286
> K>   Approved by:		gnn(mentor)
> K> 
> K> Modified:
> K>   head/sys/netpfil/pf/pf.c
> K> 
> K> Modified: head/sys/netpfil/pf/pf.c
> K> ==============================================================================
> K> --- head/sys/netpfil/pf/pf.c	Tue Apr 14 18:57:50 2015	(r281535)
> K> +++ head/sys/netpfil/pf/pf.c	Tue Apr 14 19:07:37 2015	(r281536)
> K> @@ -6070,7 +6070,7 @@ pf_test6(int dir, struct ifnet *ifp, str
> K>  
> K>  	M_ASSERTPKTHDR(m);
> K>  
> K> -	if (ifp != m->m_pkthdr.rcvif)
> K> +	if (dir == PF_OUT && m->m_pkthdr.rcvif && ifp != m->m_pkthdr.rcvif)
> K>  		fwdir = PF_FWD;
> 
> The ifp argument to pf_test6() is always not NULL, so the (m->m_pkthdr.rcvif)
> conjunct is extraneous.
> 
m->pkthdr.rcvif can be NULL though (e.g. when this is a locally
generated packet). In that case we don't want to forward, which we'd end
up doing because, as you say, ifp won't be NULL.

(In other words: If m->pkthdr.rcvif is NULL we don't forward, even if
ifp != m->pkthdr.rcvif.)

Regards,
Kristof