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Message-ID: <20070103163828.14635.74153.stgit@nienna.balabit>
Date: Wed, 03 Jan 2007 17:38:28 +0100
From: KOVACS Krisztian <hidden@...abit.hu>
To: netfilter-devel@...ts.netfilter.org, netdev@...r.kernel.org
Subject: [PATCH/RFC 09/10] iptables TPROXY target
The TPROXY target implements redirection of non-local TCP/UDP traffic
to local sockets. It is simply a wrapper around functionality exported
from iptable_tproxy.
Signed-off-by: KOVACS Krisztian <hidden@...abit.hu>
---
include/linux/netfilter_ipv4/ipt_TPROXY.h | 9 +++
net/ipv4/netfilter/Kconfig | 11 +++
net/ipv4/netfilter/Makefile | 1
net/ipv4/netfilter/ipt_TPROXY.c | 103 +++++++++++++++++++++++++++++
4 files changed, 124 insertions(+), 0 deletions(-)
diff --git a/include/linux/netfilter_ipv4/ipt_TPROXY.h b/include/linux/netfilter_ipv4/ipt_TPROXY.h
new file mode 100644
index 0000000..d05c956
--- /dev/null
+++ b/include/linux/netfilter_ipv4/ipt_TPROXY.h
@@ -0,0 +1,9 @@
+#ifndef _IPT_TPROXY_H_target
+#define _IPT_TPROXY_H_target
+
+struct ipt_tproxy_target_info {
+ u_int16_t lport;
+ u_int32_t laddr;
+};
+
+#endif
diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 312b0ef..7f76ab6 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -662,6 +662,17 @@ config IP_NF_TPROXY
To compile it as a module, choose M here. If unsure, say N.
+config IP_NF_TARGET_TPROXY
+ tristate "TPROXY target support"
+ depends on IP_NF_TPROXY
+ help
+ This option adds a `TPROXY' target, which is somewhat similar to
+ REDIRECT. It can only be used in the tproxy table and is useful
+ to redirect traffic to a transparent proxy. It does _not_ depend
+ on Netfilter connection tracking.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
# ARP tables
config IP_NF_ARPTABLES
tristate "ARP tables support"
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index aa57ce4..851da93 100644
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -97,6 +97,7 @@ obj-$(CONFIG_IP_NF_TARGET_ULOG) += ipt_U
obj-$(CONFIG_IP_NF_TARGET_TCPMSS) += ipt_TCPMSS.o
obj-$(CONFIG_IP_NF_TARGET_CLUSTERIP) += ipt_CLUSTERIP.o
obj-$(CONFIG_IP_NF_TARGET_TTL) += ipt_TTL.o
+obj-$(CONFIG_IP_NF_TARGET_TPROXY) += ipt_TPROXY.o
# generic ARP tables
obj-$(CONFIG_IP_NF_ARPTABLES) += arp_tables.o
diff --git a/net/ipv4/netfilter/ipt_TPROXY.c b/net/ipv4/netfilter/ipt_TPROXY.c
new file mode 100644
index 0000000..6f64717
--- /dev/null
+++ b/net/ipv4/netfilter/ipt_TPROXY.c
@@ -0,0 +1,103 @@
+/*
+ * Transparent proxy support for Linux/iptables
+ *
+ * Copyright (c) 2006-2007 BalaBit IT Ltd.
+ * Author: Balazs Scheidler, Krisztian Kovacs
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <net/checksum.h>
+#include <net/udp.h>
+#include <net/inet_sock.h>
+
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ip_tproxy.h>
+#include <linux/netfilter_ipv4/ipt_TPROXY.h>
+
+static unsigned int
+target(struct sk_buff **pskb,
+ const struct net_device *in,
+ const struct net_device *out,
+ unsigned int hooknum,
+ const struct xt_target *target,
+ const void *targinfo)
+{
+ const struct iphdr *iph = (*pskb)->nh.iph;
+ unsigned int verdict = NF_ACCEPT;
+ struct sk_buff *skb = *pskb;
+ struct udphdr _hdr, *hp;
+ struct sock *sk;
+
+ /* TCP/UDP only */
+ if ((iph->protocol != IPPROTO_TCP) &&
+ (iph->protocol != IPPROTO_UDP))
+ return NF_ACCEPT;
+
+ if (in == NULL)
+ return NF_ACCEPT;
+
+ if ((skb->dst != NULL) || (skb->ip_tproxy == 1))
+ return NF_ACCEPT;
+
+ hp = skb_header_pointer(*pskb, iph->ihl * 4, sizeof(_hdr), &_hdr);
+ if (hp == NULL)
+ return NF_DROP;
+
+ sk = ip_tproxy_get_sock(iph->protocol,
+ iph->saddr, iph->daddr,
+ hp->source, hp->dest, in);
+ if (sk != NULL) {
+ if (ip_tproxy_do_divert(skb, sk, 0, in) < 0)
+ verdict = NF_DROP;
+ sock_put(sk);
+ }
+
+ return verdict;
+}
+
+static int
+checkentry(const char *tablename,
+ const void *e,
+ const struct xt_target *target,
+ void *targinfo,
+ unsigned int hook_mask)
+{
+ /* checks are now done by the x_tables core based on
+ * information specified in the ipt_target structure */
+ return 1;
+}
+
+static struct ipt_target ipt_tproxy_reg = {
+ .name = "TPROXY",
+ .target = target,
+ .targetsize = sizeof(struct ipt_tproxy_target_info),
+ .table = "tproxy",
+ .checkentry = checkentry,
+ .me = THIS_MODULE,
+};
+
+static int __init init(void)
+{
+ if (ipt_register_target(&ipt_tproxy_reg))
+ return -EINVAL;
+
+ return 0;
+}
+
+static void __exit fini(void)
+{
+ ipt_unregister_target(&ipt_tproxy_reg);
+}
+
+module_init(init);
+module_exit(fini);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Krisztian Kovacs <hidden@...abit.hu>");
+MODULE_DESCRIPTION("Netfilter transparent proxy TPROXY target module.");
-
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