[patch v2.2 0/4] IPVS full NAT support + netfilter 'ipvs' match support

[patch v2.2 0/4] IPVS full NAT support + netfilter 'ipvs' match support

[Simon Horman]

[re-reposting without bogus headers that vger dislikes]

This is a repost of a patch-series posted by Hannes Eder last Steptember.
This is v2 of the patch series and I don't see any outstanding objections to
it in the mailing list archives. I would like it considered for inclusion
in the nf-next-2.6 kernel tree and iptables.

The original cover-email from Hannes follows.
The diffstat output has been updated to reflect minor up-porting by me.

From:	Hannes Eder <heder@google.com>

The following series implements full NAT support for IPVS.  The
approach is via a minimal change to IPVS (make friends with
nf_conntrack) and adding a netfilter matcher, kernel- and user-space
part, i.e. xt_ipvs and libxt_ipvs.

Example usage:

% ipvsadm -A -t 192.168.100.30:80 -s rr
% ipvsadm -a -t 192.168.100.30:80 -r 192.168.10.20:80 -m
# ...

# Source NAT for VIP 192.168.100.30:80
% iptables -t nat -A POSTROUTING -m ipvs --vaddr 192.168.100.30/32 \
> --vport 80 -j SNAT --to-source 192.168.10.10

or SNAT-ing only a specific real server:

% iptables -t nat -A POSTROUTING --dst 192.168.11.20 \
> -m ipvs --vaddr 192.168.100.30/32 -j SNAT --to-source 192.168.10.10


First of all, thanks for all the feedback.  This is the changelog for v2:

- Make ip_vs_ftp work again.  Setup nf_conntrack expectations for
  related data connections (based on Julian's patch see
  http://www.ssi.bg/~ja/nfct/) and let nf_conntrack/nf_nat do the
  packet mangling and the TCP sequence adjusting.

  This change rises the question how to deal with ip_vs_sync?  Does it
  work together with conntrackd?  Wild idea: what about getting rid of
  ip_vs_sync and piggy packing all on nf_conntrack and use conntrackd?

  Any comments on this?

- xt_ipvs: add new rule '--vportctl port' to match the VIP port of the
  controlling connection, e.g. port 21 for FTP.  Can be used to match
  a related data connection for FTP:

  # SNAT FTP control connection
  % iptables -t nat -A POSTROUTING -m ipvs --vaddr 192.168.100.30/32 \
  > --vport 21 -j SNAT --to-source 192.168.10.10
  
  # SNAT FTP passive data connection
  % iptables -t nat -A POSTROUTING -m ipvs --vaddr 192.168.100.30/32 \
  > --vportctl 21 -j SNAT --to-source 192.168.10.10

- xt_ipvs: use 'par->family' instead of 'skb->protocol'

- xt_ipvs: add ipvs_mt_check and restrict to NFPROTO_IPV4 and NFPROTO_IPV6

- Call nf_conntrack_alter_reply(), so helper lookup is performed based
  on the changed tuple.

Changes to the linux kernel (rebased to next-20090925):

Hannes Eder (3):
      netfilter: xt_ipvs (netfilter matcher for IPVS)
      IPVS: make friends with nf_conntrack
      IPVS: make FTP work with full NAT support


 include/linux/netfilter/xt_ipvs.h |   25 +++++
 include/net/ip_vs.h               |    2 
 net/netfilter/Kconfig             |    9 ++
 net/netfilter/Makefile            |    1 
 net/netfilter/ipvs/Kconfig        |    4 -
 net/netfilter/ipvs/ip_vs_app.c    |   43 ---------
 net/netfilter/ipvs/ip_vs_core.c   |   37 -------
 net/netfilter/ipvs/ip_vs_ftp.c    |  178 ++++++++++++++++++++++++++++++++---
 net/netfilter/ipvs/ip_vs_proto.c  |    1 
 net/netfilter/ipvs/ip_vs_xmit.c   |   30 ++++++
 net/netfilter/xt_ipvs.c           |  187 +++++++++++++++++++++++++++++++++++++
 11 files changed, 418 insertions(+), 99 deletions(-)
 create mode 100644 include/linux/netfilter/xt_ipvs.h
 create mode 100644 net/netfilter/xt_ipvs.c


Changes to iptables (relative to 1.4.5):

Hannes Eder (1):
      libxt_ipvs: user-space lib for netfilter matcher xt_ipvs

 configure.ac                      |   10 1
 extensions/libxt_ipvs.c           |  365 +++++++++++++++++++++++++++++++++++++
 extensions/libxt_ipvs.man         |   24 ++
 include/linux/netfilter/xt_ipvs.h |   25 +++
 4 files changed, 422 insertions(+), 2 deletions(-)
 create mode 100644 extensions/libxt_ipvs.c
 create mode 100644 extensions/libxt_ipvs.man
 create mode 100644 include/linux/netfilter/xt_ipvs.h

[patch v2.2 1/4] [PATCH v2.1 1/4] netfilter: xt_ipvs (netfilter matcher for IPVS)

[Simon Horman]

[-- Attachment #1: 1.patch --]
[-- Type: text/plain, Size: 8092 bytes --]

From:	Hannes Eder <heder@google.com>

This implements the kernel-space side of the netfilter matcher
xt_ipvs.

Signed-off-by: Hannes Eder <heder@google.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

 include/linux/netfilter/xt_ipvs.h |   25 +++++
 net/netfilter/Kconfig             |    9 ++
 net/netfilter/Makefile            |    1 
 net/netfilter/ipvs/ip_vs_proto.c  |    1 
 net/netfilter/xt_ipvs.c           |  187 +++++++++++++++++++++++++++++++++++++
 5 files changed, 223 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/netfilter/xt_ipvs.h
 create mode 100644 net/netfilter/xt_ipvs.c

Index: nf-next-2.6/include/linux/netfilter/xt_ipvs.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ nf-next-2.6/include/linux/netfilter/xt_ipvs.h	2010-04-29 20:11:53.000000000 +0900
@@ -0,0 +1,25 @@
+#ifndef _XT_IPVS_H
+#define _XT_IPVS_H 1
+
+#define XT_IPVS_IPVS_PROPERTY	(1 << 0) /* all other options imply this one */
+#define XT_IPVS_PROTO		(1 << 1)
+#define XT_IPVS_VADDR		(1 << 2)
+#define XT_IPVS_VPORT		(1 << 3)
+#define XT_IPVS_DIR		(1 << 4)
+#define XT_IPVS_METHOD		(1 << 5)
+#define XT_IPVS_VPORTCTL	(1 << 6)
+#define XT_IPVS_MASK		((1 << 7) - 1)
+#define XT_IPVS_ONCE_MASK	(XT_IPVS_MASK & ~XT_IPVS_IPVS_PROPERTY)
+
+struct xt_ipvs_mtinfo {
+	union nf_inet_addr	vaddr, vmask;
+	__be16			vport;
+	__u16			l4proto;
+	__u16			fwd_method;
+	__be16			vportctl;
+
+	__u8			invert;
+	__u8			bitmask;
+};
+
+#endif /* _XT_IPVS_H */
Index: nf-next-2.6/net/netfilter/Kconfig
===================================================================
--- nf-next-2.6.orig/net/netfilter/Kconfig	2010-04-29 20:11:51.000000000 +0900
+++ nf-next-2.6/net/netfilter/Kconfig	2010-04-29 20:11:53.000000000 +0900
@@ -703,6 +703,15 @@ config NETFILTER_XT_MATCH_IPRANGE
 
 	If unsure, say M.
 
+config NETFILTER_XT_MATCH_IPVS
+	tristate '"ipvs" match support'
+	depends on IP_VS
+	depends on NETFILTER_ADVANCED
+	help
+	  This option allows you to match against IPVS properties of a packet.
+
+	  If unsure, say N.
+
 config NETFILTER_XT_MATCH_LENGTH
 	tristate '"length" match support'
 	depends on NETFILTER_ADVANCED
Index: nf-next-2.6/net/netfilter/Makefile
===================================================================
--- nf-next-2.6.orig/net/netfilter/Makefile	2010-04-29 20:11:51.000000000 +0900
+++ nf-next-2.6/net/netfilter/Makefile	2010-04-29 20:11:53.000000000 +0900
@@ -73,6 +73,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_HASHLIMI
 obj-$(CONFIG_NETFILTER_XT_MATCH_HELPER) += xt_helper.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_HL) += xt_hl.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_IPRANGE) += xt_iprange.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_IPVS) += xt_ipvs.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_LENGTH) += xt_length.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_LIMIT) += xt_limit.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_MAC) += xt_mac.o
Index: nf-next-2.6/net/netfilter/ipvs/ip_vs_proto.c
===================================================================
--- nf-next-2.6.orig/net/netfilter/ipvs/ip_vs_proto.c	2010-04-29 20:11:51.000000000 +0900
+++ nf-next-2.6/net/netfilter/ipvs/ip_vs_proto.c	2010-04-29 20:11:53.000000000 +0900
@@ -97,6 +97,7 @@ struct ip_vs_protocol * ip_vs_proto_get(
 
 	return NULL;
 }
+EXPORT_SYMBOL(ip_vs_proto_get);
 
 
 /*
Index: nf-next-2.6/net/netfilter/xt_ipvs.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ nf-next-2.6/net/netfilter/xt_ipvs.c	2010-04-29 20:11:53.000000000 +0900
@@ -0,0 +1,187 @@
+/*
+ *	xt_ipvs - kernel module to match IPVS connection properties
+ *
+ *	Author: Hannes Eder <heder@google.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/spinlock.h>
+#include <linux/skbuff.h>
+#ifdef CONFIG_IP_VS_IPV6
+#include <net/ipv6.h>
+#endif
+#include <linux/ip_vs.h>
+#include <linux/types.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_ipvs.h>
+#include <net/netfilter/nf_conntrack.h>
+
+#include <net/ip_vs.h>
+
+MODULE_AUTHOR("Hannes Eder <heder@google.com>");
+MODULE_DESCRIPTION("Xtables: match IPVS connection properties");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_ipvs");
+MODULE_ALIAS("ip6t_ipvs");
+
+/* borrowed from xt_conntrack */
+static bool ipvs_mt_addrcmp(const union nf_inet_addr *kaddr,
+			    const union nf_inet_addr *uaddr,
+			    const union nf_inet_addr *umask,
+			    unsigned int l3proto)
+{
+	if (l3proto == NFPROTO_IPV4)
+		return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
+#ifdef CONFIG_IP_VS_IPV6
+	else if (l3proto == NFPROTO_IPV6)
+		return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
+		       &uaddr->in6) == 0;
+#endif
+	else
+		return false;
+}
+
+static bool ipvs_mt(const struct sk_buff *skb, const struct xt_match_param *par)
+{
+	const struct xt_ipvs_mtinfo *data = par->matchinfo;
+	/* ipvs_mt_check ensures that family is only NFPROTO_IPV[46]. */
+	const u_int8_t family = par->family;
+	struct ip_vs_iphdr iph;
+	struct ip_vs_protocol *pp;
+	struct ip_vs_conn *cp;
+	bool match = true;
+
+	if (data->bitmask == XT_IPVS_IPVS_PROPERTY) {
+		match = skb->ipvs_property ^
+			!!(data->invert & XT_IPVS_IPVS_PROPERTY);
+		goto out;
+	}
+
+	/* other flags than XT_IPVS_IPVS_PROPERTY are set */
+	if (!skb->ipvs_property) {
+		match = false;
+		goto out;
+	}
+
+	ip_vs_fill_iphdr(family, skb_network_header(skb), &iph);
+
+	if (data->bitmask & XT_IPVS_PROTO)
+		if ((iph.protocol == data->l4proto) ^
+		    !(data->invert & XT_IPVS_PROTO)) {
+			match = false;
+			goto out;
+		}
+
+	pp = ip_vs_proto_get(iph.protocol);
+	if (unlikely(!pp)) {
+		match = false;
+		goto out;
+	}
+
+	/*
+	 * Check if the packet belongs to an existing entry
+	 */
+	cp = pp->conn_out_get(family, skb, pp, &iph, iph.len, 1 /* inverse */);
+	if (unlikely(cp == NULL)) {
+		match = false;
+		goto out;
+	}
+
+	/*
+	 * We found a connection, i.e. ct != 0, make sure to call
+	 * __ip_vs_conn_put before returning.  In our case jump to out_put_con.
+	 */
+
+	if (data->bitmask & XT_IPVS_VPORT)
+		if ((cp->vport == data->vport) ^
+		    !(data->invert & XT_IPVS_VPORT)) {
+			match = false;
+			goto out_put_cp;
+		}
+
+	if (data->bitmask & XT_IPVS_VPORTCTL)
+		if ((cp->control != NULL &&
+		     cp->control->vport == data->vportctl) ^
+		    !(data->invert & XT_IPVS_VPORTCTL)) {
+			match = false;
+			goto out_put_cp;
+		}
+
+	if (data->bitmask & XT_IPVS_DIR) {
+		enum ip_conntrack_info ctinfo;
+		struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+
+		if (ct == NULL || ct == &nf_conntrack_untracked) {
+			match = false;
+			goto out_put_cp;
+		}
+
+		if ((ctinfo >= IP_CT_IS_REPLY) ^
+		    !!(data->invert & XT_IPVS_DIR)) {
+			match = false;
+			goto out_put_cp;
+		}
+	}
+
+	if (data->bitmask & XT_IPVS_METHOD)
+		if (((cp->flags & IP_VS_CONN_F_FWD_MASK) == data->fwd_method) ^
+		    !(data->invert & XT_IPVS_METHOD)) {
+			match = false;
+			goto out_put_cp;
+		}
+
+	if (data->bitmask & XT_IPVS_VADDR) {
+		if (ipvs_mt_addrcmp(&cp->vaddr, &data->vaddr,
+				    &data->vmask, family) ^
+		    !(data->invert & XT_IPVS_VADDR)) {
+			match = false;
+			goto out_put_cp;
+		}
+	}
+
+out_put_cp:
+	__ip_vs_conn_put(cp);
+out:
+	pr_debug("match=%d\n", match);
+	return match;
+}
+
+static bool ipvs_mt_check(const struct xt_mtchk_param *par)
+{
+	if (par->family != NFPROTO_IPV4
+#ifdef CONFIG_IP_VS_IPV6
+	    && par->family != NFPROTO_IPV6
+#endif
+		) {
+		pr_info("protocol family %u not supported\n", par->family);
+		return false;
+	}
+
+	return true;
+}
+
+static struct xt_match xt_ipvs_mt_reg __read_mostly = {
+	.name       = "ipvs",
+	.revision   = 0,
+	.family     = NFPROTO_UNSPEC,
+	.match      = ipvs_mt,
+	.checkentry = ipvs_mt_check,
+	.matchsize  = XT_ALIGN(sizeof(struct xt_ipvs_mtinfo)),
+	.me         = THIS_MODULE,
+};
+
+static int __init ipvs_mt_init(void)
+{
+	return xt_register_match(&xt_ipvs_mt_reg);
+}
+
+static void __exit ipvs_mt_exit(void)
+{
+	xt_unregister_match(&xt_ipvs_mt_reg);
+}
+
+module_init(ipvs_mt_init);
+module_exit(ipvs_mt_exit);

Re: [patch v2.2 1/4] [PATCH v2.1 1/4] netfilter: xt_ipvs (netfilter matcher for IPVS)

[Patrick McHardy]

Simon Horman wrote:

> @@ -0,0 +1,25 @@
> +#ifndef _XT_IPVS_H
> +#define _XT_IPVS_H 1

You don't need to define a value.

> +config NETFILTER_XT_MATCH_IPVS
> +	tristate '"ipvs" match support'
> +	depends on IP_VS
> +	depends on NETFILTER_ADVANCED
> +	help
> +	  This option allows you to match against IPVS properties of a packet.
> +
> +	  If unsure, say N.

You're using conntrack symbols, so this seems to need a dependency
on NF_CONNTRACK.

> +static bool ipvs_mt_check(const struct xt_mtchk_param *par)

We've changed the signature to "int" in nf-next to be able to
return errno codes. Please rebase your patches onto nf-next-2.6.git.

Please also CC netfilter-devel at least for those parts that affect
non-IPVS netfilter.

> +{
> +	if (par->family != NFPROTO_IPV4
> +#ifdef CONFIG_IP_VS_IPV6
> +	    && par->family != NFPROTO_IPV6
> +#endif
> +		) {
> +		pr_info("protocol family %u not supported\n", par->family);
> +		return false;
> +	}
> +
> +	return true;
> +}

Re: [patch v2.2 1/4] [PATCH v2.1 1/4] netfilter: xt_ipvs (netfilter matcher for IPVS)

[Hannes Eder]

Thank you for picking this series of patches up again and thanks for
the feedback.

I'll send an updated version in the next days.

Cheers, -Hannes

On Sat, May 1, 2010 at 18:18, Patrick McHardy <kaber@trash.net> wrote:
> Simon Horman wrote:
>
>> @@ -0,0 +1,25 @@
>> +#ifndef _XT_IPVS_H
>> +#define _XT_IPVS_H 1
>
> You don't need to define a value.
>
>> +config NETFILTER_XT_MATCH_IPVS
>> +     tristate '"ipvs" match support'
>> +     depends on IP_VS
>> +     depends on NETFILTER_ADVANCED
>> +     help
>> +       This option allows you to match against IPVS properties of a packet.
>> +
>> +       If unsure, say N.
>
> You're using conntrack symbols, so this seems to need a dependency
> on NF_CONNTRACK.
>
>> +static bool ipvs_mt_check(const struct xt_mtchk_param *par)
>
> We've changed the signature to "int" in nf-next to be able to
> return errno codes. Please rebase your patches onto nf-next-2.6.git.
>
> Please also CC netfilter-devel at least for those parts that affect
> non-IPVS netfilter.
>
>> +{
>> +     if (par->family != NFPROTO_IPV4
>> +#ifdef CONFIG_IP_VS_IPV6
>> +         && par->family != NFPROTO_IPV6
>> +#endif
>> +             ) {
>> +             pr_info("protocol family %u not supported\n", par->family);
>> +             return false;
>> +     }
>> +
>> +     return true;
>> +}
>
>

Re: [patch v2.2 1/4] [PATCH v2.1 1/4] netfilter: xt_ipvs (netfilter matcher for IPVS)

[Simon Horman]

On Mon, May 03, 2010 at 01:29:46PM +0200, Hannes Eder wrote:
> Thank you for picking this series of patches up again and thanks for
> the feedback.
> 
> I'll send an updated version in the next days.

Hi Hanes,

more than a few days seems to have passed.
Do you have time to fix the patches up?
If not, I'll take a stab at it.

Thanks

Re: [patch v2.2 1/4] [PATCH v2.1 1/4] netfilter: xt_ipvs (netfilter matcher for IPVS)

[Hannes Eder]

Hi Simon,

On Tue, Jun 22, 2010 at 09:13, Simon Horman <horms@verge.net.au> wrote:
> On Mon, May 03, 2010 at 01:29:46PM +0200, Hannes Eder wrote:
>> Thank you for picking this series of patches up again and thanks for
>> the feedback.
>>
>> I'll send an updated version in the next days.
>
> Hi Hanes,
>
> more than a few days seems to have passed.
> Do you have time to fix the patches up?
> If not, I'll take a stab at it.

/me working through the backlog of emails after vacation, however this
email was buried in my inbox before my vacation, my bad.  I've been
extremely busy lately and I did not have the time to work on the
patches.  I saw your updated versions, I appreciate very much that you
are taking it from there.

Cheers,
-Hannes

Re: [patch v2.2 1/4] [PATCH v2.1 1/4] netfilter: xt_ipvs (netfilter matcher for IPVS)

[Simon Horman]

On Tue, Jul 20, 2010 at 02:44:11PM +0200, Hannes Eder wrote:
> Hi Simon,
> 
> On Tue, Jun 22, 2010 at 09:13, Simon Horman <horms@verge.net.au> wrote:
> > On Mon, May 03, 2010 at 01:29:46PM +0200, Hannes Eder wrote:
> >> Thank you for picking this series of patches up again and thanks for
> >> the feedback.
> >>
> >> I'll send an updated version in the next days.
> >
> > Hi Hanes,
> >
> > more than a few days seems to have passed.
> > Do you have time to fix the patches up?
> > If not, I'll take a stab at it.
> 
> /me working through the backlog of emails after vacation, however this
> email was buried in my inbox before my vacation, my bad.  I've been
> extremely busy lately and I did not have the time to work on the
> patches.  I saw your updated versions, I appreciate very much that you
> are taking it from there.

No problem, I assumed that you were busy with something.

[patch v2.2 2/4] [PATCH v2.1 2/4] IPVS: make friends with nf_conntrack

[Simon Horman]

[-- Attachment #1: 2.patch --]
[-- Type: text/plain, Size: 5469 bytes --]

From:	Hannes Eder <heder@google.com>

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

Signed-off-by: Hannes Eder <heder@google.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

 net/netfilter/ipvs/Kconfig      |    2 +-
 net/netfilter/ipvs/ip_vs_core.c |   36 ------------------------------------
 net/netfilter/ipvs/ip_vs_xmit.c |   30 ++++++++++++++++++++++++++++++
 3 files changed, 31 insertions(+), 37 deletions(-)

Index: nf-next-2.6/net/netfilter/ipvs/Kconfig
===================================================================
--- nf-next-2.6.orig/net/netfilter/ipvs/Kconfig	2010-04-29 20:11:51.000000000 +0900
+++ nf-next-2.6/net/netfilter/ipvs/Kconfig	2010-04-29 20:11:59.000000000 +0900
@@ -3,7 +3,7 @@
 #
 menuconfig IP_VS
 	tristate "IP virtual server support"
-	depends on NET && INET && NETFILTER
+	depends on NET && INET && NETFILTER && NF_CONNTRACK
 	---help---
 	  IP Virtual Server support will let you build a high-performance
 	  virtual server based on cluster of two or more real servers. This
Index: nf-next-2.6/net/netfilter/ipvs/ip_vs_core.c
===================================================================
--- nf-next-2.6.orig/net/netfilter/ipvs/ip_vs_core.c	2010-04-29 20:11:51.000000000 +0900
+++ nf-next-2.6/net/netfilter/ipvs/ip_vs_core.c	2010-04-29 20:11:59.000000000 +0900
@@ -521,26 +521,6 @@ int ip_vs_leave(struct ip_vs_service *sv
 	return NF_DROP;
 }
 
-
-/*
- *      It is hooked before NF_IP_PRI_NAT_SRC at the NF_INET_POST_ROUTING
- *      chain, and is used for VS/NAT.
- *      It detects packets for VS/NAT connections and sends the packets
- *      immediately. This can avoid that iptable_nat mangles the packets
- *      for VS/NAT.
- */
-static unsigned int ip_vs_post_routing(unsigned int hooknum,
-				       struct sk_buff *skb,
-				       const struct net_device *in,
-				       const struct net_device *out,
-				       int (*okfn)(struct sk_buff *))
-{
-	if (!skb->ipvs_property)
-		return NF_ACCEPT;
-	/* The packet was sent from IPVS, exit this chain */
-	return NF_STOP;
-}
-
 __sum16 ip_vs_checksum_complete(struct sk_buff *skb, int offset)
 {
 	return csum_fold(skb_checksum(skb, offset, skb->len - offset, 0));
@@ -1443,14 +1423,6 @@ static struct nf_hook_ops ip_vs_ops[] __
 		.hooknum        = NF_INET_FORWARD,
 		.priority       = 99,
 	},
-	/* Before the netfilter connection tracking, exit from POST_ROUTING */
-	{
-		.hook		= ip_vs_post_routing,
-		.owner		= THIS_MODULE,
-		.pf		= PF_INET,
-		.hooknum        = NF_INET_POST_ROUTING,
-		.priority       = NF_IP_PRI_NAT_SRC-1,
-	},
 #ifdef CONFIG_IP_VS_IPV6
 	/* After packet filtering, forward packet through VS/DR, VS/TUN,
 	 * or VS/NAT(change destination), so that filtering rules can be
@@ -1479,14 +1451,6 @@ static struct nf_hook_ops ip_vs_ops[] __
 		.hooknum        = NF_INET_FORWARD,
 		.priority       = 99,
 	},
-	/* Before the netfilter connection tracking, exit from POST_ROUTING */
-	{
-		.hook		= ip_vs_post_routing,
-		.owner		= THIS_MODULE,
-		.pf		= PF_INET6,
-		.hooknum        = NF_INET_POST_ROUTING,
-		.priority       = NF_IP6_PRI_NAT_SRC-1,
-	},
 #endif
 };
 
Index: nf-next-2.6/net/netfilter/ipvs/ip_vs_xmit.c
===================================================================
--- nf-next-2.6.orig/net/netfilter/ipvs/ip_vs_xmit.c	2010-04-29 20:11:51.000000000 +0900
+++ nf-next-2.6/net/netfilter/ipvs/ip_vs_xmit.c	2010-04-29 20:11:59.000000000 +0900
@@ -27,6 +27,7 @@
 #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>
@@ -347,6 +348,31 @@ ip_vs_bypass_xmit_v6(struct sk_buff *skb
 }
 #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 || ct == &nf_conntrack_untracked ||
+	    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
@@ -402,6 +428,8 @@ ip_vs_nat_xmit(struct sk_buff *skb, stru
 
 	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. */
@@ -478,6 +506,8 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, s
 
 	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. */

Re: [patch v2.2 2/4] [PATCH v2.1 2/4] IPVS: make friends with nf_conntrack

[Patrick McHardy]

Looks good to me.

[patch v2.2 3/4] [PATCH v2.1 3/4] IPVS: make FTP work with full NAT support

[Simon Horman]

[-- Attachment #1: 3.patch --]
[-- Type: text/plain, Size: 12051 bytes --]

From:	Hannes Eder <heder@google.com>

Use nf_conntrack/nf_nat code to do the packet mangling and the TCP
sequence adjusting.  The function 'ip_vs_skb_replace' is now dead
code, so it is removed.

To SNAT FTP, use something like:

% iptables -t nat -A POSTROUTING -m ipvs --vaddr 192.168.100.30/32 \
> --vport 21 -j SNAT --to-source 192.168.10.10

and for the data connections in passive mode:

% iptables -t nat -A POSTROUTING -m ipvs --vaddr 192.168.100.30/32 \
> --vportctl 21 -j SNAT --to-source 192.168.10.10

using '-m state --state RELATED' would also works.

Make sure the kernel modules ip_vs_ftp, nf_conntrack_ftp, and
nf_nat_ftp are loaded.

[ trivial up-port by Simon Horman <horms@verge.net.au> ]
Signed-off-by: Hannes Eder <heder@google.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

--- 

 include/net/ip_vs.h             |    2 
 net/netfilter/ipvs/Kconfig      |    2 
 net/netfilter/ipvs/ip_vs_app.c  |   43 ---------
 net/netfilter/ipvs/ip_vs_core.c |    1 
 net/netfilter/ipvs/ip_vs_ftp.c  |  178 ++++++++++++++++++++++++++++++++++++---
 5 files changed, 164 insertions(+), 62 deletions(-)


Index: nf-next-2.6/include/net/ip_vs.h
===================================================================
--- nf-next-2.6.orig/include/net/ip_vs.h	2010-04-29 20:11:51.000000000 +0900
+++ nf-next-2.6/include/net/ip_vs.h	2010-04-29 20:12:03.000000000 +0900
@@ -716,8 +716,6 @@ extern void ip_vs_app_inc_put(struct ip_
 
 extern int ip_vs_app_pkt_out(struct ip_vs_conn *, struct sk_buff *skb);
 extern int ip_vs_app_pkt_in(struct ip_vs_conn *, struct sk_buff *skb);
-extern int ip_vs_skb_replace(struct sk_buff *skb, gfp_t pri,
-			     char *o_buf, int o_len, char *n_buf, int n_len);
 extern int ip_vs_app_init(void);
 extern void ip_vs_app_cleanup(void);
 
Index: nf-next-2.6/net/netfilter/ipvs/Kconfig
===================================================================
--- nf-next-2.6.orig/net/netfilter/ipvs/Kconfig	2010-04-29 20:11:59.000000000 +0900
+++ nf-next-2.6/net/netfilter/ipvs/Kconfig	2010-04-29 20:12:03.000000000 +0900
@@ -231,7 +231,7 @@ comment 'IPVS application helper'
 
 config	IP_VS_FTP
   	tristate "FTP protocol helper"
-        depends on IP_VS_PROTO_TCP
+        depends on IP_VS_PROTO_TCP && NF_NAT
 	---help---
 	  FTP is a protocol that transfers IP address and/or port number in
 	  the payload. In the virtual server via Network Address Translation,
Index: nf-next-2.6/net/netfilter/ipvs/ip_vs_app.c
===================================================================
--- nf-next-2.6.orig/net/netfilter/ipvs/ip_vs_app.c	2010-04-29 20:11:51.000000000 +0900
+++ nf-next-2.6/net/netfilter/ipvs/ip_vs_app.c	2010-04-29 20:12:03.000000000 +0900
@@ -568,49 +568,6 @@ static const struct file_operations ip_v
 };
 #endif
 
-
-/*
- *	Replace a segment of data with a new segment
- */
-int ip_vs_skb_replace(struct sk_buff *skb, gfp_t pri,
-		      char *o_buf, int o_len, char *n_buf, int n_len)
-{
-	int diff;
-	int o_offset;
-	int o_left;
-
-	EnterFunction(9);
-
-	diff = n_len - o_len;
-	o_offset = o_buf - (char *)skb->data;
-	/* The length of left data after o_buf+o_len in the skb data */
-	o_left = skb->len - (o_offset + o_len);
-
-	if (diff <= 0) {
-		memmove(o_buf + n_len, o_buf + o_len, o_left);
-		memcpy(o_buf, n_buf, n_len);
-		skb_trim(skb, skb->len + diff);
-	} else if (diff <= skb_tailroom(skb)) {
-		skb_put(skb, diff);
-		memmove(o_buf + n_len, o_buf + o_len, o_left);
-		memcpy(o_buf, n_buf, n_len);
-	} else {
-		if (pskb_expand_head(skb, skb_headroom(skb), diff, pri))
-			return -ENOMEM;
-		skb_put(skb, diff);
-		memmove(skb->data + o_offset + n_len,
-			skb->data + o_offset + o_len, o_left);
-		skb_copy_to_linear_data_offset(skb, o_offset, n_buf, n_len);
-	}
-
-	/* must update the iph total length here */
-	ip_hdr(skb)->tot_len = htons(skb->len);
-
-	LeaveFunction(9);
-	return 0;
-}
-
-
 int __init ip_vs_app_init(void)
 {
 	/* we will replace it with proc_net_ipvs_create() soon */
Index: nf-next-2.6/net/netfilter/ipvs/ip_vs_core.c
===================================================================
--- nf-next-2.6.orig/net/netfilter/ipvs/ip_vs_core.c	2010-04-29 20:11:59.000000000 +0900
+++ nf-next-2.6/net/netfilter/ipvs/ip_vs_core.c	2010-04-29 20:12:03.000000000 +0900
@@ -52,7 +52,6 @@
 
 EXPORT_SYMBOL(register_ip_vs_scheduler);
 EXPORT_SYMBOL(unregister_ip_vs_scheduler);
-EXPORT_SYMBOL(ip_vs_skb_replace);
 EXPORT_SYMBOL(ip_vs_proto_name);
 EXPORT_SYMBOL(ip_vs_conn_new);
 EXPORT_SYMBOL(ip_vs_conn_in_get);
Index: nf-next-2.6/net/netfilter/ipvs/ip_vs_ftp.c
===================================================================
--- nf-next-2.6.orig/net/netfilter/ipvs/ip_vs_ftp.c	2010-04-29 20:11:51.000000000 +0900
+++ nf-next-2.6/net/netfilter/ipvs/ip_vs_ftp.c	2010-04-29 20:12:03.000000000 +0900
@@ -20,6 +20,17 @@
  *
  * Author:	Wouter Gadeyne
  *
+ *
+ * Code for ip_vs_expect_related and ip_vs_expect_callback is taken from
+ * http://www.ssi.bg/~ja/nfct/:
+ *
+ * ip_vs_nfct.c:	Netfilter connection tracking support for IPVS
+ *
+ * Portions Copyright (C) 2001-2002
+ * Antefacto Ltd, 181 Parnell St, Dublin 1, Ireland.
+ *
+ * Portions Copyright (C) 2003-2008
+ * Julian Anastasov
  */
 
 #define KMSG_COMPONENT "IPVS"
@@ -32,6 +43,9 @@
 #include <linux/in.h>
 #include <linux/ip.h>
 #include <linux/netfilter.h>
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_nat_helper.h>
 #include <net/protocol.h>
 #include <net/tcp.h>
 #include <asm/unaligned.h>
@@ -42,6 +56,16 @@
 #define SERVER_STRING "227 Entering Passive Mode ("
 #define CLIENT_STRING "PORT "
 
+#define FMT_TUPLE	"%u.%u.%u.%u:%u->%u.%u.%u.%u:%u/%u"
+#define ARG_TUPLE(T)	NIPQUAD((T)->src.u3.ip), ntohs((T)->src.u.all), \
+			NIPQUAD((T)->dst.u3.ip), ntohs((T)->dst.u.all), \
+			(T)->dst.protonum
+
+#define FMT_CONN	"%u.%u.%u.%u:%u->%u.%u.%u.%u:%u->%u.%u.%u.%u:%u/%u:%u"
+#define ARG_CONN(C)	NIPQUAD((C)->caddr), ntohs((C)->cport), \
+			NIPQUAD((C)->vaddr), ntohs((C)->vport), \
+			NIPQUAD((C)->daddr), ntohs((C)->dport), \
+			(C)->protocol, (C)->state
 
 /*
  * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
@@ -122,6 +146,119 @@ static int ip_vs_ftp_get_addrport(char *
 	return 1;
 }
 
+/*
+ * Called from init_conntrack() as expectfn handler.
+ */
+static void
+ip_vs_expect_callback(struct nf_conn *ct,
+		      struct nf_conntrack_expect *exp)
+{
+	struct nf_conntrack_tuple *orig, new_reply;
+	struct ip_vs_conn *cp;
+
+	if (exp->tuple.src.l3num != PF_INET)
+		return;
+
+	/*
+	 * We assume that no NF locks are held before this callback.
+	 * ip_vs_conn_out_get and ip_vs_conn_in_get should match their
+	 * expectations even if they use wildcard values, now we provide the
+	 * actual values from the newly created original conntrack direction.
+	 * The conntrack is confirmed when packet reaches IPVS hooks.
+	 */
+
+	/* RS->CLIENT */
+	orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
+	cp = ip_vs_conn_out_get(exp->tuple.src.l3num, orig->dst.protonum,
+				&orig->src.u3, orig->src.u.tcp.port,
+				&orig->dst.u3, orig->dst.u.tcp.port);
+	if (cp) {
+		/* Change reply CLIENT->RS to CLIENT->VS */
+		new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+		IP_VS_DBG(7, "%s(): ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
+			  FMT_TUPLE ", found inout cp=" FMT_CONN "\n",
+			  __func__, ct, ct->status,
+			  ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
+			  ARG_CONN(cp));
+		new_reply.dst.u3 = cp->vaddr;
+		new_reply.dst.u.tcp.port = cp->vport;
+		IP_VS_DBG(7, "%s(): ct=%p, new tuples=" FMT_TUPLE ", " FMT_TUPLE
+			  ", inout cp=" FMT_CONN "\n",
+			  __func__, ct,
+			  ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
+			  ARG_CONN(cp));
+		goto alter;
+	}
+
+	/* CLIENT->VS */
+	cp = ip_vs_conn_in_get(exp->tuple.src.l3num, orig->dst.protonum,
+			       &orig->src.u3, orig->src.u.tcp.port,
+			       &orig->dst.u3, orig->dst.u.tcp.port);
+	if (cp) {
+		/* Change reply VS->CLIENT to RS->CLIENT */
+		new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+		IP_VS_DBG(7, "%s(): ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
+			  FMT_TUPLE ", found outin cp=" FMT_CONN "\n",
+			  __func__, ct, ct->status,
+			  ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
+			  ARG_CONN(cp));
+		new_reply.src.u3 = cp->daddr;
+		new_reply.src.u.tcp.port = cp->dport;
+		IP_VS_DBG(7, "%s(): ct=%p, new tuples=" FMT_TUPLE ", "
+			  FMT_TUPLE ", outin cp=" FMT_CONN "\n",
+			  __func__, ct,
+			  ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
+			  ARG_CONN(cp));
+		goto alter;
+	}
+
+	IP_VS_DBG(7, "%s(): ct=%p, status=0x%lX, tuple=" FMT_TUPLE
+		  " - unknown expect\n",
+		  __func__, ct, ct->status, ARG_TUPLE(orig));
+	return;
+
+alter:
+	/* Never alter conntrack for non-NAT conns */
+	if (IP_VS_FWD_METHOD(cp) == IP_VS_CONN_F_MASQ)
+		nf_conntrack_alter_reply(ct, &new_reply);
+	ip_vs_conn_put(cp);
+	return;
+}
+
+/*
+ * Create NF conntrack expectation with wildcard (optional) source port.
+ * Then the default callback function will alter the reply and will confirm
+ * the conntrack entry when the first packet comes.
+ */
+static void
+ip_vs_expect_related(struct sk_buff *skb, struct nf_conn *ct,
+		     struct ip_vs_conn *cp, u_int8_t proto,
+		     const __be16 *port, int from_rs)
+{
+	struct nf_conntrack_expect *exp;
+
+	BUG_ON(!ct || ct == &nf_conntrack_untracked);
+
+	exp = nf_ct_expect_alloc(ct);
+	if (!exp)
+		return;
+
+	if (from_rs)
+		nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
+				  nf_ct_l3num(ct), &cp->daddr, &cp->caddr,
+				  proto, port, &cp->cport);
+	else
+		nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
+				  nf_ct_l3num(ct), &cp->caddr, &cp->vaddr,
+				  proto, port, &cp->vport);
+
+	exp->expectfn = ip_vs_expect_callback;
+
+	IP_VS_DBG(7, "%s(): ct=%p, expect tuple=" FMT_TUPLE "\n",
+		  __func__, ct, ARG_TUPLE(&exp->tuple));
+	nf_ct_expect_related(exp);
+	nf_ct_expect_put(exp);
+}
 
 /*
  * Look at outgoing ftp packets to catch the response to a PASV command
@@ -146,9 +283,11 @@ static int ip_vs_ftp_out(struct ip_vs_ap
 	union nf_inet_addr from;
 	__be16 port;
 	struct ip_vs_conn *n_cp;
-	char buf[24];		/* xxx.xxx.xxx.xxx,ppp,ppp\000 */
+	char buf[sizeof("xxx,xxx,xxx,xxx,ppp,ppp")];
 	unsigned buf_len;
 	int ret;
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct;
 
 #ifdef CONFIG_IP_VS_IPV6
 	/* This application helper doesn't work with IPv6 yet,
@@ -208,23 +347,26 @@ static int ip_vs_ftp_out(struct ip_vs_ap
 		 */
 		from.ip = n_cp->vaddr.ip;
 		port = n_cp->vport;
-		sprintf(buf, "%u,%u,%u,%u,%u,%u", NIPQUAD(from.ip),
-			(ntohs(port)>>8)&255, ntohs(port)&255);
-		buf_len = strlen(buf);
+		buf_len = sprintf(buf, "%u,%u,%u,%u,%u,%u", NIPQUAD(from.ip),
+				  (ntohs(port)>>8)&255, ntohs(port)&255);
+
+		ct = nf_ct_get(skb, &ctinfo);
+		ret = nf_nat_mangle_tcp_packet(skb,
+					       ct,
+					       ctinfo,
+					       start-data,
+					       end-start,
+					       buf,
+					       buf_len);
+
+		if (ct && ct != &nf_conntrack_untracked)
+			ip_vs_expect_related(skb, ct, n_cp,
+					     IPPROTO_TCP, NULL, 0);
 
 		/*
-		 * Calculate required delta-offset to keep TCP happy
+		 * Not setting 'diff' is intentional, otherwise the sequence
+		 * would be adjusted twice.
 		 */
-		*diff = buf_len - (end-start);
-
-		if (*diff == 0) {
-			/* simply replace it with new passive address */
-			memcpy(start, buf, buf_len);
-			ret = 1;
-		} else {
-			ret = !ip_vs_skb_replace(skb, GFP_ATOMIC, start,
-					  end-start, buf, buf_len);
-		}
 
 		cp->app_data = NULL;
 		ip_vs_tcp_conn_listen(n_cp);
@@ -256,6 +398,7 @@ static int ip_vs_ftp_in(struct ip_vs_app
 	union nf_inet_addr to;
 	__be16 port;
 	struct ip_vs_conn *n_cp;
+	struct nf_conn *ct;
 
 #ifdef CONFIG_IP_VS_IPV6
 	/* This application helper doesn't work with IPv6 yet,
@@ -342,6 +485,11 @@ static int ip_vs_ftp_in(struct ip_vs_app
 		ip_vs_control_add(n_cp, cp);
 	}
 
+	ct = (struct nf_conn *)skb->nfct;
+	if (ct && ct != &nf_conntrack_untracked)
+		ip_vs_expect_related(skb, ct, n_cp,
+				     IPPROTO_TCP, &n_cp->dport, 1);
+
 	/*
 	 *	Move tunnel to listen state
 	 */

Re: [patch v2.2 3/4] [PATCH v2.1 3/4] IPVS: make FTP work with full NAT support

[Patrick McHardy]

Simon Horman wrote:

> +#define FMT_TUPLE	"%u.%u.%u.%u:%u->%u.%u.%u.%u:%u/%u"
> +#define ARG_TUPLE(T)	NIPQUAD((T)->src.u3.ip), ntohs((T)->src.u.all), \
> +			NIPQUAD((T)->dst.u3.ip), ntohs((T)->dst.u.all), \
> +			(T)->dst.protonum
> +
> +#define FMT_CONN	"%u.%u.%u.%u:%u->%u.%u.%u.%u:%u->%u.%u.%u.%u:%u/%u:%u"
> +#define ARG_CONN(C)	NIPQUAD((C)->caddr), ntohs((C)->cport), \
> +			NIPQUAD((C)->vaddr), ntohs((C)->vport), \
> +			NIPQUAD((C)->daddr), ntohs((C)->dport), \
> +			(C)->protocol, (C)->state
>  

Please use the appropriate format string (%pI4) instead of NIPQUAD.

> +		buf_len = sprintf(buf, "%u,%u,%u,%u,%u,%u", NIPQUAD(from.ip),
> +				  (ntohs(port)>>8)&255, ntohs(port)&255);
> +
> +		ct = nf_ct_get(skb, &ctinfo);
> +		ret = nf_nat_mangle_tcp_packet(skb,
> +					       ct,
> +					       ctinfo,
> +					       start-data,
> +					       end-start,
> +					       buf,
> +					       buf_len);
> +
> +		if (ct && ct != &nf_conntrack_untracked)

ct is non-NULL, otherwise we'll crash in nf_nat_mangle_tcp_packet().
Are you sure you want to mangle untracked packets above? That doesn't
work when their are size changes.

[patch v2.2 4/4] [PATCH v2.1 4/4] libxt_ipvs: user-space lib for netfilter matcher xt_ipvs

[Simon Horman]

[-- Attachment #1: 4.patch --]
[-- Type: text/plain, Size: 13571 bytes --]

From:	Hannes Eder <heder@google.com>

The user-space library for the netfilter matcher xt_ipvs.

[ trivial up-port by Simon Horman <horms@verge.net.au> ]
Signed-off-by: Hannes Eder <heder@google.com>
Acked-by: Simon Horman <horms@verge.net.au>

 configure.ac                      |   10 -
 extensions/libxt_ipvs.c           |  365 +++++++++++++++++++++++++++++++++++++
 extensions/libxt_ipvs.man         |   24 ++
 include/linux/netfilter/xt_ipvs.h |   25 +++
 4 files changed, 422 insertions(+), 2 deletions(-)
 create mode 100644 extensions/libxt_ipvs.c
 create mode 100644 extensions/libxt_ipvs.man
 create mode 100644 include/linux/netfilter/xt_ipvs.h

diff --git a/configure.ac b/configure.ac
index 0419ea7..52e9223 100644
--- a/configure.ac
+++ b/configure.ac
@@ -47,12 +46,18 @@ AC_ARG_WITH([pkgconfigdir], AS_HELP_STRING([--with-pkgconfigdir=PATH],
 	[Path to the pkgconfig directory [[LIBDIR/pkgconfig]]]),
 	[pkgconfigdir="$withval"], [pkgconfigdir='${libdir}/pkgconfig'])
 
-AC_CHECK_HEADER([linux/dccp.h])
-
 blacklist_modules="";
+
+AC_CHECK_HEADER([linux/dccp.h])
 if test "$ac_cv_header_linux_dccp_h" != "yes"; then
 	blacklist_modules="$blacklist_modules dccp";
 fi;
+
+AC_CHECK_HEADER([linux/ip_vs.h])
+if test "$ac_cv_header_linux_ip_vs_h" != "yes"; then
+	blacklist_modules="$blacklist_modules ipvs";
+fi;
+
 AC_SUBST([blacklist_modules])
 
 AM_CONDITIONAL([ENABLE_STATIC], [test "$enable_static" = "yes"])
diff --git a/extensions/libxt_ipvs.c b/extensions/libxt_ipvs.c
new file mode 100644
index 0000000..6843551
--- /dev/null
+++ b/extensions/libxt_ipvs.c
@@ -0,0 +1,365 @@
+/*
+ * Shared library add-on to iptables to add IPVS matching.
+ *
+ * Detailed doc is in the kernel module source net/netfilter/xt_ipvs.c
+ *
+ * Author: Hannes Eder <heder@google.com>
+ */
+#include <sys/types.h>
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <getopt.h>
+#include <netdb.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <xtables.h>
+#include <linux/ip_vs.h>
+#include <linux/netfilter/xt_ipvs.h>
+
+static const struct option ipvs_mt_opts[] = {
+	{ .name = "ipvs",     .has_arg = false, .val = '0' },
+	{ .name = "vproto",   .has_arg = true,  .val = '1' },
+	{ .name = "vaddr",    .has_arg = true,  .val = '2' },
+	{ .name = "vport",    .has_arg = true,  .val = '3' },
+	{ .name = "vdir",     .has_arg = true,  .val = '4' },
+	{ .name = "vmethod",  .has_arg = true,  .val = '5' },
+	{ .name = "vportctl", .has_arg = true,  .val = '6' },
+	{ .name = NULL }
+};
+
+static void ipvs_mt_help(void)
+{
+	printf(
+"IPVS match options:\n"
+"[!] --ipvs                      packet belongs to an IPVS connection\n"
+"\n"
+"Any of the following options implies --ipvs (even negated)\n"
+"[!] --vproto protocol           VIP protocol to match; by number or name,\n"
+"                                e.g. \"tcp\"\n"
+"[!] --vaddr address[/mask]      VIP address to match\n"
+"[!] --vport port                VIP port to match; by number or name,\n"
+"                                e.g. \"http\"\n"
+"    --vdir {ORIGINAL|REPLY}     flow direction of packet\n"
+"[!] --vmethod {GATE|IPIP|MASQ}  IPVS forwarding method used\n"
+"[!] --vportctl port             VIP port of the controlling connection to\n"
+"                                match, e.g. 21 for FTP\n"
+		);
+}
+
+static void ipvs_mt_parse_addr_and_mask(const char *arg,
+					union nf_inet_addr *address,
+					union nf_inet_addr *mask,
+					unsigned int family)
+{
+	struct in_addr *addr = NULL;
+	struct in6_addr *addr6 = NULL;
+	unsigned int naddrs = 0;
+
+	if (family == NFPROTO_IPV4) {
+		xtables_ipparse_any(arg, &addr, &mask->in, &naddrs);
+		if (naddrs > 1)
+			xtables_error(PARAMETER_PROBLEM,
+				      "multiple IP addresses not allowed");
+		if (naddrs == 1)
+			memcpy(&address->in, addr, sizeof(*addr));
+	} else if (family == NFPROTO_IPV6) {
+		xtables_ip6parse_any(arg, &addr6, &mask->in6, &naddrs);
+		if (naddrs > 1)
+			xtables_error(PARAMETER_PROBLEM,
+				      "multiple IP addresses not allowed");
+		if (naddrs == 1)
+			memcpy(&address->in6, addr6, sizeof(*addr6));
+	} else {
+		/* Hu? */
+		assert(false);
+	}
+}
+
+/* Function which parses command options; returns true if it ate an option */
+static int ipvs_mt_parse(int c, char **argv, int invert, unsigned int *flags,
+			 const void *entry, struct xt_entry_match **match,
+			 unsigned int family)
+{
+	struct xt_ipvs_mtinfo *data = (void *)(*match)->data;
+	char *p = NULL;
+	u_int8_t op = 0;
+
+	if ('0' <= c && c <= '6') {
+		static const int ops[] = {
+			XT_IPVS_IPVS_PROPERTY,
+			XT_IPVS_PROTO,
+			XT_IPVS_VADDR,
+			XT_IPVS_VPORT,
+			XT_IPVS_DIR,
+			XT_IPVS_METHOD,
+			XT_IPVS_VPORTCTL
+		};
+		op = ops[c - '0'];
+	} else
+		return 0;
+
+	if (*flags & op & XT_IPVS_ONCE_MASK)
+		goto multiple_use;
+
+	switch (c) {
+	case '0': /* --ipvs */
+		/* Nothing to do here. */
+		break;
+
+	case '1': /* --vproto */
+		/* Canonicalize into lower case */
+		for (p = optarg; *p != '\0'; ++p)
+			*p = tolower(*p);
+
+		data->l4proto = xtables_parse_protocol(optarg);
+		break;
+
+	case '2': /* --vaddr */
+		ipvs_mt_parse_addr_and_mask(optarg, &data->vaddr,
+					    &data->vmask, family);
+		break;
+
+	case '3': /* --vport */
+		data->vport = htons(xtables_parse_port(optarg, "tcp"));
+		break;
+
+	case '4': /* --vdir */
+		xtables_param_act(XTF_NO_INVERT, "ipvs", "--vdir", invert);
+		if (strcasecmp(optarg, "ORIGINAL") == 0) {
+			data->bitmask |= XT_IPVS_DIR;
+			data->invert   &= ~XT_IPVS_DIR;
+		} else if (strcasecmp(optarg, "REPLY") == 0) {
+			data->bitmask |= XT_IPVS_DIR;
+			data->invert  |= XT_IPVS_DIR;
+		} else {
+			xtables_param_act(XTF_BAD_VALUE,
+					  "ipvs", "--vdir", optarg);
+		}
+		break;
+
+	case '5': /* --vmethod */
+		if (strcasecmp(optarg, "GATE") == 0)
+			data->fwd_method = IP_VS_CONN_F_DROUTE;
+		else if (strcasecmp(optarg, "IPIP") == 0)
+			data->fwd_method = IP_VS_CONN_F_TUNNEL;
+		else if (strcasecmp(optarg, "MASQ") == 0)
+			data->fwd_method = IP_VS_CONN_F_MASQ;
+		else
+			xtables_param_act(XTF_BAD_VALUE,
+					  "ipvs", "--vmethod", optarg);
+		break;
+
+	case '6': /* --vportctl */
+		data->vportctl = htons(xtables_parse_port(optarg, "tcp"));
+		break;
+
+	default:
+		/* Hu? How did we come here? */
+		assert(false);
+		return 0;
+	}
+
+	if (op & XT_IPVS_ONCE_MASK) {
+		if (data->invert & XT_IPVS_IPVS_PROPERTY)
+			xtables_error(PARAMETER_PROBLEM,
+				      "! --ipvs cannot be together with"
+				      " other options");
+		data->bitmask |= XT_IPVS_IPVS_PROPERTY;
+	}
+
+	data->bitmask |= op;
+	if (invert)
+		data->invert |= op;
+	*flags |= op;
+	return 1;
+
+multiple_use:
+	xtables_error(PARAMETER_PROBLEM,
+		      "multiple use of the same IPVS option is not allowed");
+}
+
+static int ipvs_mt4_parse(int c, char **argv, int invert, unsigned int *flags,
+			  const void *entry, struct xt_entry_match **match)
+{
+	return ipvs_mt_parse(c, argv, invert, flags, entry, match,
+			     NFPROTO_IPV4);
+}
+
+static int ipvs_mt6_parse(int c, char **argv, int invert, unsigned int *flags,
+			  const void *entry, struct xt_entry_match **match)
+{
+	return ipvs_mt_parse(c, argv, invert, flags, entry, match,
+			     NFPROTO_IPV6);
+}
+
+static void ipvs_mt_check(unsigned int flags)
+{
+	if (flags == 0)
+		xtables_error(PARAMETER_PROBLEM,
+			      "IPVS: At least one option is required");
+}
+
+/* Shamelessly copied from libxt_conntrack.c */
+static void ipvs_mt_dump_addr(const union nf_inet_addr *addr,
+			      const union nf_inet_addr *mask,
+			      unsigned int family, bool numeric)
+{
+	char buf[BUFSIZ];
+
+	if (family == NFPROTO_IPV4) {
+		if (!numeric && addr->ip == 0) {
+			printf("anywhere ");
+			return;
+		}
+		if (numeric)
+			strcpy(buf, xtables_ipaddr_to_numeric(&addr->in));
+		else
+			strcpy(buf, xtables_ipaddr_to_anyname(&addr->in));
+		strcat(buf, xtables_ipmask_to_numeric(&mask->in));
+		printf("%s ", buf);
+	} else if (family == NFPROTO_IPV6) {
+		if (!numeric && addr->ip6[0] == 0 && addr->ip6[1] == 0 &&
+		    addr->ip6[2] == 0 && addr->ip6[3] == 0) {
+			printf("anywhere ");
+			return;
+		}
+		if (numeric)
+			strcpy(buf, xtables_ip6addr_to_numeric(&addr->in6));
+		else
+			strcpy(buf, xtables_ip6addr_to_anyname(&addr->in6));
+		strcat(buf, xtables_ip6mask_to_numeric(&mask->in6));
+		printf("%s ", buf);
+	}
+}
+
+static void ipvs_mt_dump(const void *ip, const struct xt_ipvs_mtinfo *data,
+			 unsigned int family, bool numeric, const char *prefix)
+{
+	if (data->bitmask == XT_IPVS_IPVS_PROPERTY) {
+		if (data->invert & XT_IPVS_IPVS_PROPERTY)
+			printf("! ");
+		printf("%sipvs ", prefix);
+	}
+
+	if (data->bitmask & XT_IPVS_PROTO) {
+		if (data->invert & XT_IPVS_PROTO)
+			printf("! ");
+		printf("%sproto %u ", prefix, data->l4proto);
+	}
+
+	if (data->bitmask & XT_IPVS_VADDR) {
+		if (data->invert & XT_IPVS_VADDR)
+			printf("! ");
+
+		printf("%svaddr ", prefix);
+		ipvs_mt_dump_addr(&data->vaddr, &data->vmask, family, numeric);
+	}
+
+	if (data->bitmask & XT_IPVS_VPORT) {
+		if (data->invert & XT_IPVS_VPORT)
+			printf("! ");
+
+		printf("%svport %u ", prefix, ntohs(data->vport));
+	}
+
+	if (data->bitmask & XT_IPVS_DIR) {
+		if (data->invert & XT_IPVS_DIR)
+			printf("%svdir REPLY ", prefix);
+		else
+			printf("%svdir ORIGINAL ", prefix);
+	}
+
+	if (data->bitmask & XT_IPVS_METHOD) {
+		if (data->invert & XT_IPVS_METHOD)
+			printf("! ");
+
+		printf("%svmethod ", prefix);
+		switch (data->fwd_method) {
+		case IP_VS_CONN_F_DROUTE:
+			printf("GATE ");
+			break;
+		case IP_VS_CONN_F_TUNNEL:
+			printf("IPIP ");
+			break;
+		case IP_VS_CONN_F_MASQ:
+			printf("MASQ ");
+			break;
+		default:
+			/* Hu? */
+			printf("UNKNOWN ");
+			break;
+		}
+	}
+
+	if (data->bitmask & XT_IPVS_VPORTCTL) {
+		if (data->invert & XT_IPVS_VPORTCTL)
+			printf("! ");
+
+		printf("%svportctl %u ", prefix, ntohs(data->vportctl));
+	}
+}
+
+static void ipvs_mt4_print(const void *ip, const struct xt_entry_match *match,
+			   int numeric)
+{
+	const struct xt_ipvs_mtinfo *data = (const void *)match->data;
+	ipvs_mt_dump(ip, data, NFPROTO_IPV4, numeric, "");
+}
+
+static void ipvs_mt6_print(const void *ip, const struct xt_entry_match *match,
+			   int numeric)
+{
+	const struct xt_ipvs_mtinfo *data = (const void *)match->data;
+	ipvs_mt_dump(ip, data, NFPROTO_IPV6, numeric, "");
+}
+
+static void ipvs_mt4_save(const void *ip, const struct xt_entry_match *match)
+{
+	const struct xt_ipvs_mtinfo *data = (const void *)match->data;
+	ipvs_mt_dump(ip, data, NFPROTO_IPV4, true, "--");
+}
+
+static void ipvs_mt6_save(const void *ip, const struct xt_entry_match *match)
+{
+	const struct xt_ipvs_mtinfo *data = (const void *)match->data;
+	ipvs_mt_dump(ip, data, NFPROTO_IPV6, true, "--");
+}
+
+static struct xtables_match ipvs_matches_reg[] = {
+	{
+		.version       = XTABLES_VERSION,
+		.name          = "ipvs",
+		.revision      = 0,
+		.family        = NFPROTO_IPV4,
+		.size          = XT_ALIGN(sizeof(struct xt_ipvs_mtinfo)),
+		.userspacesize = XT_ALIGN(sizeof(struct xt_ipvs_mtinfo)),
+		.help          = ipvs_mt_help,
+		.parse         = ipvs_mt4_parse,
+		.final_check   = ipvs_mt_check,
+		.print         = ipvs_mt4_print,
+		.save          = ipvs_mt4_save,
+		.extra_opts    = ipvs_mt_opts,
+	},
+	{
+		.version       = XTABLES_VERSION,
+		.name          = "ipvs",
+		.revision      = 0,
+		.family        = NFPROTO_IPV6,
+		.size          = XT_ALIGN(sizeof(struct xt_ipvs_mtinfo)),
+		.userspacesize = XT_ALIGN(sizeof(struct xt_ipvs_mtinfo)),
+		.help          = ipvs_mt_help,
+		.parse         = ipvs_mt6_parse,
+		.final_check   = ipvs_mt_check,
+		.print         = ipvs_mt6_print,
+		.save          = ipvs_mt6_save,
+		.extra_opts    = ipvs_mt_opts,
+	},
+};
+
+void _init(void)
+{
+	xtables_register_matches(ipvs_matches_reg,
+				 ARRAY_SIZE(ipvs_matches_reg));
+}
diff --git a/extensions/libxt_ipvs.man b/extensions/libxt_ipvs.man
new file mode 100644
index 0000000..8968e1a
--- /dev/null
+++ b/extensions/libxt_ipvs.man
@@ -0,0 +1,24 @@
+Match IPVS connection properties.
+.TP
+[\fB!\fR] \fB\-\-ipvs\fP
+packet belongs to an IPVS connection
+.TP
+Any of the following options implies \-\-ipvs (even negated)
+.TP
+[\fB!\fR] \fB\-\-vproto\fP \fIprotocol\fP
+VIP protocol to match; by number or name, e.g. "tcp"
+.TP
+[\fB!\fR] \fB\-\-vaddr\fP \fIaddress\fP[\fB/\fP\fImask\fP]
+VIP address to match
+.TP
+[\fB!\fR] \fB\-\-vport\fP \fIport\fP
+VIP port to match; by number or name, e.g. "http"
+.TP
+\fB\-\-vdir\fP {\fBORIGINAL\fP|\fBREPLY\fP}
+flow direction of packet
+.TP
+[\fB!\fR] \fB\-\-vmethod\fP {\fBGATE\fP|\fBIPIP\fP|\fBMASQ\fP}
+IPVS forwarding method used
+.TP
+[\fB!\fR] \fB\-\-vportctl\fP \fIport\fP
+VIP port of the controlling connection to match, e.g. 21 for FTP
diff --git a/include/linux/netfilter/xt_ipvs.h b/include/linux/netfilter/xt_ipvs.h
new file mode 100644
index 0000000..32f3051
--- /dev/null
+++ b/include/linux/netfilter/xt_ipvs.h
@@ -0,0 +1,25 @@
+#ifndef _XT_IPVS_H
+#define _XT_IPVS_H 1
+
+#define XT_IPVS_IPVS_PROPERTY	(1 << 0) /* all other options imply this one */
+#define XT_IPVS_PROTO		(1 << 1)
+#define XT_IPVS_VADDR		(1 << 2)
+#define XT_IPVS_VPORT		(1 << 3)
+#define XT_IPVS_DIR		(1 << 4)
+#define XT_IPVS_METHOD		(1 << 5)
+#define XT_IPVS_VPORTCTL	(1 << 6)
+#define XT_IPVS_MASK		((1 << 7) - 1)
+#define XT_IPVS_ONCE_MASK	(XT_IPVS_MASK & ~XT_IPVS_IPVS_PROPERTY)
+
+struct xt_ipvs_mtinfo {
+	union nf_inet_addr	vaddr, vmask;
+	__be16			vport;
+	__u16			l4proto;
+	__u16			fwd_method;
+	__be16			vportctl;
+
+	__u8			invert;
+	__u8			bitmask;
+};
+
+#endif /* _XT_IPVS_H */