2 * Transparent proxy support for Linux/iptables
4 * Copyright (c) 2006-2007 BalaBit IT Ltd.
5 * Author: Balazs Scheidler, Krisztian Kovacs
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
16 #include <net/checksum.h>
18 #include <net/inet_sock.h>
20 #include <linux/netfilter/x_tables.h>
21 #include <linux/netfilter_ipv4/ip_tables.h>
22 #include <linux/netfilter/xt_TPROXY.h>
24 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
25 #include <net/netfilter/nf_tproxy_core.h>
28 tproxy_tg(struct sk_buff *skb, const struct xt_action_param *par)
30 const struct iphdr *iph = ip_hdr(skb);
31 const struct xt_tproxy_target_info *tgi = par->targinfo;
32 struct udphdr _hdr, *hp;
35 hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
39 sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
41 tgi->laddr ? tgi->laddr : iph->daddr,
43 tgi->lport ? tgi->lport : hp->dest,
46 /* NOTE: assign_sock consumes our sk reference */
47 if (sk && nf_tproxy_assign_sock(skb, sk)) {
48 /* This should be in a separate target, but we don't do multiple
49 targets on the same rule yet */
50 skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
52 pr_debug("redirecting: proto %u %08x:%u -> %08x:%u, mark: %x\n",
53 iph->protocol, ntohl(iph->daddr), ntohs(hp->dest),
54 ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark);
58 pr_debug("no socket, dropping: proto %u %08x:%u -> %08x:%u, mark: %x\n",
59 iph->protocol, ntohl(iph->daddr), ntohs(hp->dest),
60 ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark);
64 static int tproxy_tg_check(const struct xt_tgchk_param *par)
66 const struct ipt_ip *i = par->entryinfo;
68 if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP)
69 && !(i->invflags & IPT_INV_PROTO))
72 pr_info("Can be used only in combination with "
73 "either -p tcp or -p udp\n");
77 static struct xt_target tproxy_tg_reg __read_mostly = {
82 .targetsize = sizeof(struct xt_tproxy_target_info),
83 .checkentry = tproxy_tg_check,
84 .hooks = 1 << NF_INET_PRE_ROUTING,
88 static int __init tproxy_tg_init(void)
90 nf_defrag_ipv4_enable();
91 return xt_register_target(&tproxy_tg_reg);
94 static void __exit tproxy_tg_exit(void)
96 xt_unregister_target(&tproxy_tg_reg);
99 module_init(tproxy_tg_init);
100 module_exit(tproxy_tg_exit);
101 MODULE_LICENSE("GPL");
102 MODULE_AUTHOR("Krisztian Kovacs");
103 MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module.");
104 MODULE_ALIAS("ipt_TPROXY");