On Fri, Nov 22, 2019 at 03:39:16PM -0500, Aaron Conole wrote: > Marcelo Ricardo Leitner <[email protected]> writes: > > > On Mon, Nov 18, 2019 at 04:21:39PM -0500, Aaron Conole wrote: > >> Marcelo Ricardo Leitner <[email protected]> writes: > >> > >> > On Fri, Nov 08, 2019 at 04:07:14PM -0500, Aaron Conole wrote: > >> >> The act_ct TC module shares a common conntrack and NAT infrastructure > >> >> exposed via netfilter. It's possible that a packet needs both SNAT and > >> >> DNAT manipulation, due to e.g. tuple collision. Netfilter can support > >> >> this because it runs through the NAT table twice - once on ingress and > >> >> again after egress. The act_ct action doesn't have such capability. > >> >> > >> >> Like netfilter hook infrastructure, we should run through NAT twice to > >> >> keep the symmetry. > >> >> > >> >> Fixes: b57dc7c13ea9 ("net/sched: Introduce action ct") > >> >> > >> >> Signed-off-by: Aaron Conole <[email protected]> > >> >> --- > >> >> net/sched/act_ct.c | 13 ++++++++++++- > >> >> 1 file changed, 12 insertions(+), 1 deletion(-) > >> >> > >> >> diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c > >> >> index fcc46025e790..f3232a00970f 100644 > >> >> --- a/net/sched/act_ct.c > >> >> +++ b/net/sched/act_ct.c > >> >> @@ -329,6 +329,7 @@ static int tcf_ct_act_nat(struct sk_buff *skb, > >> >> bool commit) > >> >> { > >> >> #if IS_ENABLED(CONFIG_NF_NAT) > >> >> + int err; > >> >> enum nf_nat_manip_type maniptype; > >> >> > >> >> if (!(ct_action & TCA_CT_ACT_NAT)) > >> >> @@ -359,7 +360,17 @@ static int tcf_ct_act_nat(struct sk_buff *skb, > >> >> return NF_ACCEPT; > >> >> } > >> >> > >> >> - return ct_nat_execute(skb, ct, ctinfo, range, maniptype); > >> >> + err = ct_nat_execute(skb, ct, ctinfo, range, maniptype); > >> >> + if (err == NF_ACCEPT && > >> >> + ct->status & IPS_SRC_NAT && ct->status & IPS_DST_NAT) { > >> >> + if (maniptype == NF_NAT_MANIP_SRC) > >> >> + maniptype = NF_NAT_MANIP_DST; > >> >> + else > >> >> + maniptype = NF_NAT_MANIP_SRC; > >> >> + > >> >> + err = ct_nat_execute(skb, ct, ctinfo, range, maniptype); > >> >> + } > >> > > >> > I keep thinking about this and I'm not entirely convinced that this > >> > shouldn't be simpler. More like: > >> > > >> > if (DNAT) > >> > DNAT > >> > if (SNAT) > >> > SNAT > >> > > >> > So it always does DNAT before SNAT, similarly to what iptables would > >> > do on PRE/POSTROUTING chains. > >> > >> I can rewrite the whole function, but I wanted to start with the smaller > >> fix that worked. I also think it needs more testing then (since it's > >> something of a rewrite of the function). > >> > >> I guess it's not too important - do you think it gives any readability > >> to do it this way? If so, I can respin the patch changing it like you > >> describe. > > > > I didn't mean a rewrite, but just to never handle SNAT before DNAT. So > > the fix here would be like: > > > > - return ct_nat_execute(skb, ct, ctinfo, range, maniptype); > > + err = ct_nat_execute(skb, ct, ctinfo, range, maniptype); > > + if (err == NF_ACCEPT && maniptype == NF_NAT_MANIP_DST && > > + ct->status & IPS_SRC_NAT && ct->status & IPS_DST_NAT) { > > + maniptype = NF_NAT_MANIP_SRC; > > + err = ct_nat_execute(skb, ct, ctinfo, range, maniptype); > > + } > > + return err; > > But the maniptype of the first call could be NAT_MANIP_SRC. In fact, > that's what I see if the packet is reply direction && !related.
Interesting, ok. > > So, we need the block to invert the manipulation type. Otherwise, we > miss the DNAT manipulation. > > So I don't think I can use that block. Thanks for digging on it. Acked-by: Marcelo Ricardo Leitner <[email protected]> > > >> >> + return err; > >> >> #else > >> >> return NF_ACCEPT; > >> >> #endif > >> >> -- > >> >> 2.21.0 > >> >> > >> > _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
