netfilter: iptables TPROXY target (e8439270) · Commits · e / devices / android_kernel_oneplus_sm7250

include/linux/netfilter/xt_TPROXY.h

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			#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 */

net/netfilter/Kconfig

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	@@ -421,6 +421,21 @@ config NETFILTER_XT_TARGET_RATEEST

	To compile it as a module, choose M here. If unsure, say N.		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		config NETFILTER_XT_TARGET_TRACE
	tristate '"TRACE" target support'		tristate '"TRACE" target support'
	depends on NETFILTER_XTABLES		depends on NETFILTER_XTABLES

net/netfilter/Makefile

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	@@ -51,6 +51,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
	obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o		obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o
	obj-$(CONFIG_NETFILTER_XT_TARGET_RATEEST) += xt_RATEEST.o		obj-$(CONFIG_NETFILTER_XT_TARGET_RATEEST) += xt_RATEEST.o
	obj-$(CONFIG_NETFILTER_XT_TARGET_SECMARK) += xt_SECMARK.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_TCPMSS) += xt_TCPMSS.o
	obj-$(CONFIG_NETFILTER_XT_TARGET_TCPOPTSTRIP) += xt_TCPOPTSTRIP.o		obj-$(CONFIG_NETFILTER_XT_TARGET_TCPOPTSTRIP) += xt_TCPOPTSTRIP.o
	obj-$(CONFIG_NETFILTER_XT_TARGET_TRACE) += xt_TRACE.o		obj-$(CONFIG_NETFILTER_XT_TARGET_TRACE) += xt_TRACE.o

net/netfilter/xt_TPROXY.c

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			/*
			* 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");