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Message-id: <20081001142431.4893.51517.stgit@este>
Date: Wed, 01 Oct 2008 16:24:31 +0200
From: KOVACS Krisztian <hidden@....bme.hu>
To: David Miller <davem@...emloft.net>
Cc: Patrick McHardy <kaber@...sh.net>, netdev@...r.kernel.org,
netfilter-devel@...r.kernel.org
Subject: [net-next PATCH 15/16] iptables TPROXY target
The TPROXY target implements redirection of non-local TCP/UDP traffic to local
sockets. Additionally, it's possible to manipulate the packet mark if and only
if a socket has been found. (We need this because we cannot use multiple
targets in the same iptables rule.)
Signed-off-by: KOVACS Krisztian <hidden@....bme.hu>
---
include/linux/netfilter/xt_TPROXY.h | 14 ++++
net/netfilter/Kconfig | 15 +++++
net/netfilter/Makefile | 1
net/netfilter/xt_TPROXY.c | 112 +++++++++++++++++++++++++++++++++++
4 files changed, 142 insertions(+), 0 deletions(-)
diff --git a/include/linux/netfilter/xt_TPROXY.h b/include/linux/netfilter/xt_TPROXY.h
new file mode 100644
index 0000000..152e8f9
--- /dev/null
+++ b/include/linux/netfilter/xt_TPROXY.h
@@ -0,0 +1,14 @@
+#ifndef _XT_TPROXY_H_target
+#define _XT_TPROXY_H_target
+
+/* TPROXY target is capable of marking the packet to perform
+ * redirection. We can get rid of that whenever we get support for
+ * mutliple targets in the same rule. */
+struct xt_tproxy_target_info {
+ u_int32_t mark_mask;
+ u_int32_t mark_value;
+ __be32 laddr;
+ __be16 lport;
+};
+
+#endif /* _XT_TPROXY_H_target */
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index a4b8006..bef2144 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -421,6 +421,21 @@ config NETFILTER_XT_TARGET_RATEEST
To compile it as a module, choose M here. If unsure, say N.
+config NETFILTER_XT_TARGET_TPROXY
+ tristate '"TPROXY" target support (EXPERIMENTAL)'
+ depends on EXPERIMENTAL
+ depends on NETFILTER_TPROXY
+ depends on NETFILTER_XTABLES
+ depends on NETFILTER_ADVANCED
+ select NF_DEFRAG_IPV4
+ help
+ This option adds a `TPROXY' target, which is somewhat similar to
+ REDIRECT. It can only be used in the mangle table and is useful
+ to redirect traffic to a transparent proxy. It does _not_ depend
+ on Netfilter connection tracking and NAT, unlike REDIRECT.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config NETFILTER_XT_TARGET_TRACE
tristate '"TRACE" target support'
depends on NETFILTER_XTABLES
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index c386755..fdb72f8 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_RATEEST) += xt_RATEEST.o
obj-$(CONFIG_NETFILTER_XT_TARGET_SECMARK) += xt_SECMARK.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_TPROXY) += xt_TPROXY.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TCPMSS) += xt_TCPMSS.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TCPOPTSTRIP) += xt_TCPOPTSTRIP.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TRACE) += xt_TRACE.o
diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
new file mode 100644
index 0000000..183f251
--- /dev/null
+++ b/net/netfilter/xt_TPROXY.c
@@ -0,0 +1,112 @@
+/*
+ * 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/x_tables.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter/xt_TPROXY.h>
+
+#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
+#include <net/netfilter/nf_tproxy_core.h>
+
+static unsigned int
+tproxy_tg(struct sk_buff *skb,
+ 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 = ip_hdr(skb);
+ const struct xt_tproxy_target_info *tgi = targinfo;
+ struct udphdr _hdr, *hp;
+ struct sock *sk;
+
+ hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
+ if (hp == NULL)
+ return NF_DROP;
+
+ sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
+ iph->saddr, tgi->laddr ? tgi->laddr : iph->daddr,
+ hp->source, tgi->lport ? tgi->lport : hp->dest,
+ in, true);
+
+ /* NOTE: assign_sock consumes our sk reference */
+ if (sk && nf_tproxy_assign_sock(skb, sk)) {
+ /* This should be in a separate target, but we don't do multiple
+ targets on the same rule yet */
+ skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
+
+ pr_debug("redirecting: proto %u %08x:%u -> %08x:%u, mark: %x\n",
+ iph->protocol, ntohl(iph->daddr), ntohs(hp->dest),
+ ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark);
+ return NF_ACCEPT;
+ }
+
+ pr_debug("no socket, dropping: proto %u %08x:%u -> %08x:%u, mark: %x\n",
+ iph->protocol, ntohl(iph->daddr), ntohs(hp->dest),
+ ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark);
+ return NF_DROP;
+}
+
+static bool
+tproxy_tg_check(const char *tablename,
+ const void *entry,
+ const struct xt_target *target,
+ void *targetinfo,
+ unsigned int hook_mask)
+{
+ const struct ipt_ip *i = entry;
+
+ if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP)
+ && !(i->invflags & IPT_INV_PROTO))
+ return true;
+
+ pr_info("xt_TPROXY: Can be used only in combination with "
+ "either -p tcp or -p udp\n");
+ return false;
+}
+
+static struct xt_target tproxy_tg_reg __read_mostly = {
+ .name = "TPROXY",
+ .family = AF_INET,
+ .table = "mangle",
+ .target = tproxy_tg,
+ .targetsize = sizeof(struct xt_tproxy_target_info),
+ .checkentry = tproxy_tg_check,
+ .hooks = 1 << NF_INET_PRE_ROUTING,
+ .me = THIS_MODULE,
+};
+
+static int __init tproxy_tg_init(void)
+{
+ nf_defrag_ipv4_enable();
+ return xt_register_target(&tproxy_tg_reg);
+}
+
+static void __exit tproxy_tg_exit(void)
+{
+ xt_unregister_target(&tproxy_tg_reg);
+}
+
+module_init(tproxy_tg_init);
+module_exit(tproxy_tg_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Krisztian Kovacs");
+MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module.");
+MODULE_ALIAS("ipt_TPROXY");
--
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