IPVS: make friends with nf_conntrack
Update the nf_conntrack tuple in reply direction, as we will see
traffic from the real server (RIP) to the client (CIP). Once this is
done we can use netfilters SNAT in POSTROUTING, especially with
xt_ipvs, to do source NAT, e.g.:
% iptables -t nat -A POSTROUTING -m ipvs --vaddr 192.168.100.30/32 --vport 80 \
-j SNAT --to-source 192.168.10.10
[ minor fixes by Simon Horman <horms@verge.net.au> ]
Signed-off-by: Hannes Eder <heder@google.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 02b078e..21e1a5e 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -28,6 +28,7 @@
#include <net/ip6_route.h>
#include <linux/icmpv6.h>
#include <linux/netfilter.h>
+#include <net/netfilter/nf_conntrack.h>
#include <linux/netfilter_ipv4.h>
#include <net/ip_vs.h>
@@ -348,6 +349,30 @@
}
#endif
+static void
+ip_vs_update_conntrack(struct sk_buff *skb, struct ip_vs_conn *cp)
+{
+ struct nf_conn *ct = (struct nf_conn *)skb->nfct;
+ struct nf_conntrack_tuple new_tuple;
+
+ if (ct == NULL || nf_ct_is_untracked(ct) || nf_ct_is_confirmed(ct))
+ return;
+
+ /*
+ * The connection is not yet in the hashtable, so we update it.
+ * CIP->VIP will remain the same, so leave the tuple in
+ * IP_CT_DIR_ORIGINAL untouched. When the reply comes back from the
+ * real-server we will see RIP->DIP.
+ */
+ new_tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+ new_tuple.src.u3 = cp->daddr;
+ /*
+ * This will also take care of UDP and other protocols.
+ */
+ new_tuple.src.u.tcp.port = cp->dport;
+ nf_conntrack_alter_reply(ct, &new_tuple);
+}
+
/*
* NAT transmitter (only for outside-to-inside nat forwarding)
* Not used for related ICMP
@@ -403,6 +428,8 @@
IP_VS_DBG_PKT(10, pp, skb, 0, "After DNAT");
+ ip_vs_update_conntrack(skb, cp);
+
/* FIXME: when application helper enlarges the packet and the length
is larger than the MTU of outgoing device, there will be still
MTU problem. */
@@ -479,6 +506,8 @@
IP_VS_DBG_PKT(10, pp, skb, 0, "After DNAT");
+ ip_vs_update_conntrack(skb, cp);
+
/* FIXME: when application helper enlarges the packet and the length
is larger than the MTU of outgoing device, there will be still
MTU problem. */