Re: [PATCHv2] extensions: libxt_cluster: Add translation to nft

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

On Tue, May 30, 2017 at 12:08:55PM +0200, Pablo Neira Ayuso wrote:
> On Tue, May 30, 2017 at 01:55:34PM +0530, Shyam Saini wrote:
> > Add translation for cluster match to nftables
> > 
> > $ sudo iptables-translate -A PREROUTING -t mangle -i eth1 -m cluster --cluster-total-nodes 2 --cluster-local-node 1 --cluster-hash-seed
> > 0xdeadbeef -j MARK --set-mark 0xffff
> > nft add rule ip mangle PREROUTING iifname eth1 jhash ct original saddr mod 2 seed 0xdeadbeef eq 0 meta pkttype set host counter meta mark set
> > 0xffff
> > 
> > $ sudo iptables-translate -A PREROUTING -t mangle -i eth1 -m cluster --cluster-total-nodes 2 --cluster-local-nodemask 1 --cluster-hash-seed
> > 0xdeadbeef -j MARK --set-mark 0xffff
> > nft add rule ip mangle PREROUTING iifname eth1 jhash ct original saddr mod 2 seed 0xdeadbeef eq 0 meta pkttype set host counter meta mark set
> > 0xffff
> > 
> >  --debug=netlink Result
> > ip mangle PREROUTING
> >   [ meta load iifname => reg 1 ]
> >   [ cmp eq reg 1 0x31687465 0x00000000 0x00000000 0x00000000 ]
> >   [ ct load src => reg 2 , dir original ]
> >   [ hash reg 1 = jhash(reg 2, 4, 0xdeadbeef) % mod 2 ]
> >   [ cmp eq reg 1 0x00000000 ]
> >   [ immediate reg 1 0x00000000 ]
> >   [ meta set pkttype with reg 1 ]
> >   [ counter pkts 0 bytes 0 ]
> >   [ immediate reg 1 0x0000ffff ]
> >   [ meta set mark with reg 1 ]
> > 
> > For Example:
> > 
> > If we have  total 2 nodes (i.e, --cluster-total-nodes is 2) in the cluster then
> >  modulus 2 = {0, 1}
> > 
> > For node 1 (--cluster-local-node 1)
> > 	jhash ct original saddr mod 2 seed 0xdeadbeef eq 0
> > 
> > For  node 2 (--cluster-local-node 2)
> > 	jhash ct original saddr mod 2 seed 0xdeadbeef eq 1
> > 
> > Signed-off-by: Shyam Saini <mayhs11saini@gmail.com>
> > ---
> >  extensions/libxt_cluster.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/extensions/libxt_cluster.c b/extensions/libxt_cluster.c
> > index 3adff12..f2abd18 100644
> > --- a/extensions/libxt_cluster.c
> > +++ b/extensions/libxt_cluster.c
> > @@ -126,6 +126,16 @@ cluster_save(const void *ip, const struct xt_entry_match *match)
> >  		info->total_nodes, info->hash_seed);
> >  }
> >  
> > +static int cluster_xlate(struct xt_xlate *xl,
> > +		const struct xt_xlate_mt_params *params)
> > +{
> > +	const struct xt_cluster_match_info *info = (const struct xt_cluster_match_info *)params->match->data;
> > +
> > +	xt_xlate_add(xl, "jhash ct original saddr mod %u seed 0x%08x eq 0 meta pkttype set host",
> 
> This should use "eq %u" because:
> 
> 	xt_xlate_add(xl, "jhash ct original saddr mod %u seed 0x%08x eq %u meta pkttype set host",

Forget this I mentioned below, got mixed with another email to you.

What I'm telling here is, the "eq %u" should be used to translate
info->node_mask.

Note that info->node_mask is a bitmask, so you have to interpret this
accordingly from the translation.

Note that we have to support --cluster-local-nodemask too, you can
translate this using a set, ie.

jhash ct original saddr mod 4 seed 0x1234 { 0, 1 } meta pkttype set host

OK?