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Re: [bug] FWMARKs and persistence in IPVS: The Use of Unions

To: Jan Engelhardt <jengelh@xxxxxxxxxx>
Subject: Re: [bug] FWMARKs and persistence in IPVS: The Use of Unions
Cc: netfilter-devel <netfilter-devel@xxxxxxxxxxxxxxx>, lvs-devel@xxxxxxxxxxxxxxx, Fabien Duchêne <fabien.duchene@xxxxxxxxxxxxxxxxxxxx>, Joseph Mack NA3T <jmack@xxxxxxxx>, Julius Volz <julius.volz@xxxxxxxxx>
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Tue, 28 Apr 2009 20:59:41 +1000
On Tue, Apr 28, 2009 at 07:23:55PM +1000, Simon Horman wrote:
> On Tue, Apr 28, 2009 at 11:07:40AM +0200, Jan Engelhardt wrote:
> > 
> > On Tuesday 2009-04-28 10:15, Simon Horman wrote:
> > >
> > >It seems to me that it should be easy enough to fix by changing
> > >fwmark in ip_vs_sched_persist() from:
> > >
> > >union nf_inet_addr fwmark = {
> > >   .all = { 0, 0, 0, htonl(svc->fwmark) }
> > >};
> > >
> > >to:
> > >
> > >union nf_inet_addr fwmark = {
> > >   .all = { htonl(svc->fwmark), 0, 0, 0 }
> > >};
> > >
> > >Assuming that this would result in fwmark->ip being set to
> > >htonl(svc->fwmark), which is relevant if svc->af is AF_INET - that is,
> > >for IPv4.[...]
> > >An alternate idea would be to change the af value used for fwmarks,
> > >but this seems to be even less clean than the current (slightly broken)
> > >technique of using nf_inet_addr for IPv4 or IPv6 addresses, or fwmarks.
> > 
> > If you use ->all, then using NFPROTO_UNSPEC as af
> > seems to me like a good match.

I am guessing that AF_UNSPEC is more appropriate than NFPROTO_UNSPEC.
Please correct me if I am wrong.

> That seems reasonable, though ip_vs_ct_in_get() would still
> need to use the real af for the cp->af == af and
> ip_vs_addr_equal(af, s_addr, &cp->caddr) portinos of the check.

It looks like checking for proto == IPPROTO_IP can tell us if
the destination is a fwmark. This is based on the assumption that
iph.protocol can never be IPPROTO_IP in ip_vs_sched_persist().

The following patch expresses these ideas as they crrently stand.
Fabien, is it possible for you to test this?

Index: net-next-2.6/net/netfilter/ipvs/ip_vs_conn.c
===================================================================
--- net-next-2.6.orig/net/netfilter/ipvs/ip_vs_conn.c   2009-04-28 
20:37:48.000000000 +1000
+++ net-next-2.6/net/netfilter/ipvs/ip_vs_conn.c        2009-04-28 
20:37:51.000000000 +1000
@@ -260,7 +260,10 @@ struct ip_vs_conn *ip_vs_ct_in_get
        list_for_each_entry(cp, &ip_vs_conn_tab[hash], c_list) {
                if (cp->af == af &&
                    ip_vs_addr_equal(af, s_addr, &cp->caddr) &&
-                   ip_vs_addr_equal(af, d_addr, &cp->vaddr) &&
+                   /* protocol should only be IPPROTO_IP if
+                    * d_addr is a fwmark */
+                   ip_vs_addr_equal(protocol == IPPROTO_IP ? AF_UNSPEC : af,
+                                    d_addr, &cp->vaddr) &&
                    s_port == cp->cport && d_port == cp->vport &&
                    cp->flags & IP_VS_CONN_F_TEMPLATE &&
                    protocol == cp->protocol) {
@@ -698,7 +701,9 @@ ip_vs_conn_new(int af, int proto, const 
        cp->cport          = cport;
        ip_vs_addr_copy(af, &cp->vaddr, vaddr);
        cp->vport          = vport;
-       ip_vs_addr_copy(af, &cp->daddr, daddr);
+       /* proto should only be IPPROTO_IP if d_addr is a fwmark */
+       ip_vs_addr_copy(proto == IPPROTO_IP ? AF_UNSPEC : af,
+                       &cp->daddr, daddr);
        cp->dport          = dport;
        cp->flags          = flags;
        spin_lock_init(&cp->lock);
Index: net-next-2.6/net/netfilter/ipvs/ip_vs_core.c
===================================================================
--- net-next-2.6.orig/net/netfilter/ipvs/ip_vs_core.c   2009-04-28 
20:37:48.000000000 +1000
+++ net-next-2.6/net/netfilter/ipvs/ip_vs_core.c        2009-04-28 
20:37:51.000000000 +1000
@@ -278,7 +278,7 @@ ip_vs_sched_persist(struct ip_vs_service
                 */
                if (svc->fwmark) {
                        union nf_inet_addr fwmark = {
-                               .all = { 0, 0, 0, htonl(svc->fwmark) }
+                               .ip = htonl(svc->fwmark)
                        };
 
                        ct = ip_vs_ct_in_get(svc->af, IPPROTO_IP, &snet, 0,
@@ -306,7 +306,7 @@ ip_vs_sched_persist(struct ip_vs_service
                         */
                        if (svc->fwmark) {
                                union nf_inet_addr fwmark = {
-                                       .all = { 0, 0, 0, htonl(svc->fwmark) }
+                                       .ip = htonl(svc->fwmark)
                                };
 
                                ct = ip_vs_conn_new(svc->af, IPPROTO_IP,


-- 
Simon Horman
  VA Linux Systems Japan K.K. Satellite Lab in Sydney, Australia
  H: www.vergenet.net/~horms/            W: www.valinux.co.jp/en

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