LVS
lvs-devel
Google
 
Web LinuxVirtualServer.org

Re: [patch v2.3 3/4] IPVS: make FTP work with full NAT support

To: Patrick McHardy <kaber@xxxxxxxxx>
Subject: Re: [patch v2.3 3/4] IPVS: make FTP work with full NAT support
Cc: lvs-devel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, netfilter@xxxxxxxxxxxxxxx, netfilter-devel@xxxxxxxxxxxxxxx, Malcolm Turnbull <malcolm@xxxxxxxxxxxxxxxx>, Wensong Zhang <wensong@xxxxxxxxxxxx>, Julius Volz <julius.volz@xxxxxxxxx>, "David S. Miller" <davem@xxxxxxxxxxxxx>, Hannes Eder <heder@xxxxxxxxxx>
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Sat, 10 Jul 2010 10:54:21 +0900
On Fri, Jul 09, 2010 at 05:24:56PM +0200, Patrick McHardy wrote:
> Am 07.07.2010 08:53, schrieb Simon Horman:
> > On Tue, Jul 06, 2010 at 01:43:44PM +0200, Patrick McHardy wrote:
> >> Simon Horman wrote:
> >>> @@ -219,19 +358,23 @@ static int ip_vs_ftp_out(struct ip_vs_ap
> >>>           buf_len = strlen(buf);
> >>> +         ct = nf_ct_get(skb, &ctinfo);
> >>> +         ret = nf_nat_mangle_tcp_packet(skb,
> >>> +                                        ct,
> >>> +                                        ctinfo,
> >>> +                                        start-data,
> >>> +                                        end-start,
> >>> +                                        buf,
> >>> +                                        buf_len);
> >>> +
> >>> +         if (ct && ct != &nf_conntrack_untracked)
> >> This does not make sense, you're already using the conntrack above
> >> in the call to nf_nat_mangle_tcp_packet(), so the check should
> >> probably happen before that. You also should be checking the
> >> return value of nf_nat_mangle_tcp_packet() before setting up the
> >> expectation.
> >>
> >>> +                 ip_vs_expect_related(skb, ct, n_cp,
> >>> +                                      IPPROTO_TCP, NULL, 0);
> > 
> > Good point. Is this better?
> > 
> >             ct = nf_ct_get(skb, &ctinfo);
> >             if (ct && !nf_ct_is_untracked()) {
> >                     ret = nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
> >                                                    start-data, end-start,
> >                                                    buf, buf_len);
> >                     if (ret)
> >                             ip_vs_expect_related(skb, ct, n_cp,
> >                                                  IPPROTO_TCP, NULL, 0);
> 
> Yes, that's better, although we're usually dropping packets
> when mangling fails. This can only happen under memory pressure,
> the assumption is that we might be able to properly mangle
> the packet when it is retransmitted.

I didn't notice this either, but ret will be end up being the return value
of ip_vs_ftp_out(), and if that is zero the packet will be dropped.

--
To unsubscribe from this list: send the line "unsubscribe lvs-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

<Prev in Thread] Current Thread [Next in Thread>