On Sep 30 2007 22:53, KOVACS Krisztian wrote:
>+struct ipt_tproxy_target_info {
>+ __be32 laddr;
>+ __be16 lport;
>+ unsigned long mark_mask;
>+ unsigned long mark_value;
>+};
Cannot use unsigned long, as its size is not fixed.
(other nitpicks that were already in xt_socket)
>+ /* 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;
I guess you mean | instead of ^ here.
>+#ifdef CONFIG_COMPAT
>+struct compat_ipt_tproxy_target_info {
>+ __be32 laddr;
>+ __be16 lport;
>+ __be16 __pad1;
>+ compat_ulong_t mark_mask;
>+ compat_ulong_t mark_value;
>+};
Uhm, that's a bit cumbersome. By reordering, we can get all the
alignment done without any premature compat code.
Find below a patch that makes me happy, and compiles. :)
[ xtification comes at no cost, even if it's ipv4-only.
Although it is just a guess, I suppose xt_ is going to replace
ipt_ and ip6t_ even if some matches/targets are not all-protocol ]
===
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.)
(originally from: KOVACS Krisztian <hidden@xxxxxxxxxx>)
A few cleanups and fixes.
Signed-off-by: Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx>
---
include/linux/netfilter/xt_TPROXY.h | 16 ++++++
net/netfilter/Kconfig | 12 ++++
net/netfilter/Makefile | 1
net/netfilter/xt_TPROXY.c | 92 ++++++++++++++++++++++++++++++++++++
4 files changed, 121 insertions(+)
Index: linux-2.6.23/include/linux/netfilter/xt_TPROXY.h
===================================================================
--- /dev/null
+++ linux-2.6.23/include/linux/netfilter/xt_TPROXY.h
@@ -0,0 +1,16 @@
+#ifndef _XT_TPROXY_H
+#define _XT_TPROXY_H
+
+/*
+ * 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_info {
+ u_int32_t mark_mask;
+ u_int32_t mark_value;
+ __be32 laddr;
+ __be16 lport;
+};
+
+#endif /* _XT_TPROXY_H */
Index: linux-2.6.23/net/netfilter/Kconfig
===================================================================
--- linux-2.6.23.orig/net/netfilter/Kconfig
+++ linux-2.6.23/net/netfilter/Kconfig
@@ -363,6 +363,18 @@ config NETFILTER_XT_TARGET_NOTRACK
If you want to compile it as a module, say M here and read
<file:Documentation/kbuild/modules.txt>. If unsure, say `N'.
+config NETFILTER_XT_TARGET_TPROXY
+ tristate '"TPROXY" target support'
+ depends on NETFILTER_TPROXY
+ depends on NETFILTER_XTABLES
+ 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.
+
config NETFILTER_XT_TARGET_TRACE
tristate '"TRACE" target support'
depends on NETFILTER_XTABLES
Index: linux-2.6.23/net/netfilter/Makefile
===================================================================
--- linux-2.6.23.orig/net/netfilter/Makefile
+++ linux-2.6.23/net/netfilter/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_NFLOG)
obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TRACE) += xt_TRACE.o
obj-$(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_CONNSECMARK) += xt_CONNSECMARK.o
Index: linux-2.6.23/net/netfilter/xt_TPROXY.c
===================================================================
--- /dev/null
+++ linux-2.6.23/net/netfilter/xt_TPROXY.c
@@ -0,0 +1,92 @@
+/*
+ * 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/inet_sock.h>
+#include <net/udp.h>
+#include <linux/netfilter/x_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_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 xt_tproxy_info *tgi = targinfo;
+ const struct iphdr *iph = ip_hdr(*pskb);
+ 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;
+
+ hp = skb_header_pointer(*pskb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
+ if (hp == NULL)
+ return NF_DROP;
+
+ sk = nf_tproxy_get_sock_v4(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 != NULL && nf_tproxy_assign_sock(skb, sk) != 0) {
+ /*
+ * This should be in a separate target, but we do not 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 struct xt_target xt_tproxy_reg = {
+ .name = "TPROXY",
+ .family = AF_INET,
+ .table = "mangle",
+ .target = tproxy_target,
+ .targetsize = sizeof(struct xt_tproxy_info),
+ .hooks = 1 << NF_IP_PRE_ROUTING,
+ .me = THIS_MODULE,
+};
+
+static int __init xt_tproxy_init(void)
+{
+ nf_defrag_ipv4_enable();
+ return xt_register_target(&xt_tproxy_reg);
+}
+
+static void __exit xt_tproxy_exit(void)
+{
+ xt_unregister_target(&xt_tproxy_reg);
+}
+
+module_init(xt_tproxy_init);
+module_exit(xt_tproxy_exit);
+MODULE_AUTHOR("Krisztian Kovacs");
+MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_TPROXY");
-
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