tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Transparent proxy support for Linux/iptables
3 *
4 * Copyright (c) 2006-2007 BalaBit IT Ltd.
5 * Author: Balazs Scheidler, Krisztian Kovacs
6 *
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.
10 *
11 */
12
13#include <linux/module.h>
14#include <linux/skbuff.h>
15#include <linux/ip.h>
16#include <net/checksum.h>
17#include <net/udp.h>
18#include <net/inet_sock.h>
19
20#include <linux/netfilter/x_tables.h>
21#include <linux/netfilter_ipv4/ip_tables.h>
22#include <linux/netfilter/xt_TPROXY.h>
23
24#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
25#include <net/netfilter/nf_tproxy_core.h>
26
27static unsigned int
28tproxy_tg(struct sk_buff *skb, const struct xt_target_param *par)
29{
30 const struct iphdr *iph = ip_hdr(skb);
31 const struct xt_tproxy_target_info *tgi = par->targinfo;
32 struct udphdr _hdr, *hp;
33 struct sock *sk;
34
35 hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
36 if (hp == NULL)
37 return NF_DROP;
38
39 sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
40 iph->saddr, tgi->laddr ? tgi->laddr : iph->daddr,
41 hp->source, tgi->lport ? tgi->lport : hp->dest,
42 par->in, true);
43
44 /* NOTE: assign_sock consumes our sk reference */
45 if (sk && nf_tproxy_assign_sock(skb, sk)) {
46 /* This should be in a separate target, but we don't do multiple
47 targets on the same rule yet */
48 skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
49
50 pr_debug("redirecting: proto %u %08x:%u -> %08x:%u, mark: %x\n",
51 iph->protocol, ntohl(iph->daddr), ntohs(hp->dest),
52 ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark);
53 return NF_ACCEPT;
54 }
55
56 pr_debug("no socket, dropping: proto %u %08x:%u -> %08x:%u, mark: %x\n",
57 iph->protocol, ntohl(iph->daddr), ntohs(hp->dest),
58 ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark);
59 return NF_DROP;
60}
61
62static bool tproxy_tg_check(const struct xt_tgchk_param *par)
63{
64 const struct ipt_ip *i = par->entryinfo;
65
66 if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP)
67 && !(i->invflags & IPT_INV_PROTO))
68 return true;
69
70 pr_info("xt_TPROXY: Can be used only in combination with "
71 "either -p tcp or -p udp\n");
72 return false;
73}
74
75static struct xt_target tproxy_tg_reg __read_mostly = {
76 .name = "TPROXY",
77 .family = AF_INET,
78 .table = "mangle",
79 .target = tproxy_tg,
80 .targetsize = sizeof(struct xt_tproxy_target_info),
81 .checkentry = tproxy_tg_check,
82 .hooks = 1 << NF_INET_PRE_ROUTING,
83 .me = THIS_MODULE,
84};
85
86static int __init tproxy_tg_init(void)
87{
88 nf_defrag_ipv4_enable();
89 return xt_register_target(&tproxy_tg_reg);
90}
91
92static void __exit tproxy_tg_exit(void)
93{
94 xt_unregister_target(&tproxy_tg_reg);
95}
96
97module_init(tproxy_tg_init);
98module_exit(tproxy_tg_exit);
99MODULE_LICENSE("GPL");
100MODULE_AUTHOR("Krisztian Kovacs");
101MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module.");
102MODULE_ALIAS("ipt_TPROXY");