Re: [PATCH nft] evaluate: add range specified flag setting (missing NF_NAT_RANGE_PROTO_SPECIFIED)

["Сергей Маринкевич" <s@marinkevich.ru>]

> Sergey reports:  > > With nf_tables it is not possible to use port range for 
masquerading. > Masquerade statement has option "to [:port-port]" which 
give no effect > to translation behavior. But it must change source port 
of packet to > one from ":port-port" range. > > My network: > > 
+-----------------------------+ > | ROUTER | > | | > | Masquerade| > | 
10.0.0.1 1.1.1.1 | > | +------+ +------+ | > | | eth1 | | eth2 | | > 
+-+--^---+-----------+---^--+-+ > | | > | | > +----v------+ 
+------v----+ > | | | | > | 10.0.0.2 | | 1.1.1.2 | > | | | | > |PC1 | 
|PC2 | > +-----------+ +-----------+ > > For testing i used rule like 
this: > > rule ip nat POSTROUTING oifname eth2 masquerade to :666 > > 
Run netcat for 1.1.1.2 667(UDP) and get dump from PC2: > > 
15:22:25.591567 a8:f9:4b:aa:08:44 > a8:f9:4b:ac:e7:8f, ethertype IPv4 
(0x0800), length 60: 1.1.1.1.34466 > 1.1.1.2.667: UDP, length 1 > > 
Address translation works fine, but source port are not belongs to > 
specified range. > > I see in similar source code (i.e. nft_redir.c, 
nft_nat.c) that > there is setting NF_NAT_RANGE_PROTO_SPECIFIED flag. 
After adding this, > repeat test for kernel with this patch, and get 
dump: > > 16:16:22.324710 a8:f9:4b:aa:08:44 > a8:f9:4b:ac:e7:8f, 
ethertype IPv4 (0x0800), length 60: 1.1.1.1.666 > 1.1.1.2.667: UDP, 
length 1 > > Now it is works fine. > > Reported-by: Sergey Marinkevich 
<s@marinkevich.ru> > Signed-off-by: Pablo Neira Ayuso 
<pablo@netfilter.org> > --- > Sergey, could you try this userspace patch 
instead? Thanks.
I tried this patch with equal environment but another
net(192.168.122.0/24). Router uses vanilla kernel v5.4.19.
Translation is the same.

     12:59:11.599887 08:00:27:ec:9c:b3 > 52:54:00:57:d2:7d, ethertype 
IPv4 (0x0800), length 60: 192.168.122.38.666 > 192.168.122.1.667: UDP, 
length 4

I think i have to add this tag:

Tested-by: Sergey Marinkevich <s@marinkevich.ru>

>  > src/evaluate.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff 
--git a/src/evaluate.c b/src/evaluate.c > index 
4a23b231c74d..d0e712dc02f0 100644 > --- a/src/evaluate.c > +++ 
b/src/evaluate.c > @@ -18,6 +18,7 @@ > #include <linux/netfilter_arp.h> 
 > #include <linux/netfilter/nf_tables.h> > #include 
<linux/netfilter/nf_synproxy.h> > +#include <linux/netfilter/nf_nat.h> > 
#include <linux/netfilter_ipv4.h> > #include <netinet/ip_icmp.h> > 
#include <netinet/icmp6.h> > @@ -2950,6 +2951,8 @@ static int 
stmt_evaluate_nat(struct eval_ctx *ctx, struct stmt *stmt) > err = 
nat_evaluate_transport(ctx, stmt, &stmt->nat.proto); > if (err < 0) > 
return err; > + > + stmt->nat.flags |= NF_NAT_RANGE_PROTO_SPECIFIED; > } 
 > > stmt->flags |= STMT_F_TERMINAL; > -- > 2.11.0