Re: [RFC] [PATCH] Handle routing changes for the MASQUERADE target

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Thu, Nov 29, 2012 at 10:26:40PM +0100, Florian Westphal wrote:
> Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> wrote:
> 
> Hi Jozsef,
> 
> this looks really good, two minor nits below.
> 
> > diff --git a/net/ipv4/netfilter/iptable_nat.c b/net/ipv4/netfilter/iptable_nat.c
> > index ac635a7..128885d 100644
> > --- a/net/ipv4/netfilter/iptable_nat.c
> > +++ b/net/ipv4/netfilter/iptable_nat.c
> > @@ -17,6 +17,7 @@
> >  #include <net/netfilter/nf_nat.h>
> >  #include <net/netfilter/nf_nat_core.h>
> >  #include <net/netfilter/nf_nat_l3proto.h>
> > +#include <net/netfilter/nf_conntrack_ecache.h>
> >  
> >  static const struct xt_table nf_nat_ipv4_table = {
> >  	.name		= "nat",
> > @@ -134,6 +135,24 @@ nf_nat_ipv4_fn(unsigned int hooknum,
> >  		/* ESTABLISHED */
> >  		NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
> >  			     ctinfo == IP_CT_ESTABLISHED_REPLY);
> > +		if (hooknum == NF_INET_POST_ROUTING &&
> > +		    CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL &&
> > +		    nat->masq_index && nat->masq_index != out->ifindex) {
> > +			/* Outgoing interface changed, kill ct.  */
> 
> Would it be possible to use nf_ct_kill_acct() here instead of
> 
> > +			if (del_timer(&ct->timeout)) {
> > +				if (nf_conntrack_event(IPCT_DESTROY, ct) < 0) {
> [..]
> 
> ?
> 
> > --- a/net/ipv6/netfilter/ip6table_nat.c
> > +++ b/net/ipv6/netfilter/ip6table_nat.c
> > @@ -19,6 +19,7 @@
> >  #include <net/netfilter/nf_nat.h>
> >  #include <net/netfilter/nf_nat_core.h>
> >  #include <net/netfilter/nf_nat_l3proto.h>
> [..]
> >  static const struct xt_table nf_nat_ipv6_table = {
> > +		if (hooknum == NF_INET_POST_ROUTING &&
> > +		    CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL &&
> > +		    nat->masq_index && nat->masq_index != out->ifindex) {
> > +			/* Outgoing interface changed, kill ct.  */
> > +			if (del_timer(&ct->timeout)) {
> 
> perhaps this could be a helper in include/net/netfilter/nf_nat.h?
> 
> It would avoid the code duplication and the needed #if IS_ENABLED() MASQ
> check.

I'd suggest a hook function that is set via rcu_pointer_assign in the
init path of the masquerade target.