Commit | Line | Data |
---|---|---|
e8439270 KK |
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 | ||
27 | static unsigned int | |
28 | tproxy_tg(struct sk_buff *skb, | |
29 | const struct net_device *in, | |
30 | const struct net_device *out, | |
31 | unsigned int hooknum, | |
32 | const struct xt_target *target, | |
33 | const void *targinfo) | |
34 | { | |
35 | const struct iphdr *iph = ip_hdr(skb); | |
36 | const struct xt_tproxy_target_info *tgi = targinfo; | |
37 | struct udphdr _hdr, *hp; | |
38 | struct sock *sk; | |
39 | ||
40 | hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); | |
41 | if (hp == NULL) | |
42 | return NF_DROP; | |
43 | ||
44 | sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol, | |
45 | iph->saddr, tgi->laddr ? tgi->laddr : iph->daddr, | |
46 | hp->source, tgi->lport ? tgi->lport : hp->dest, | |
47 | in, true); | |
48 | ||
49 | /* NOTE: assign_sock consumes our sk reference */ | |
50 | if (sk && nf_tproxy_assign_sock(skb, sk)) { | |
51 | /* This should be in a separate target, but we don't do multiple | |
52 | targets on the same rule yet */ | |
53 | skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value; | |
54 | ||
55 | pr_debug("redirecting: proto %u %08x:%u -> %08x:%u, mark: %x\n", | |
56 | iph->protocol, ntohl(iph->daddr), ntohs(hp->dest), | |
57 | ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark); | |
58 | return NF_ACCEPT; | |
59 | } | |
60 | ||
61 | pr_debug("no socket, dropping: proto %u %08x:%u -> %08x:%u, mark: %x\n", | |
62 | iph->protocol, ntohl(iph->daddr), ntohs(hp->dest), | |
63 | ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark); | |
64 | return NF_DROP; | |
65 | } | |
66 | ||
67 | static bool | |
68 | tproxy_tg_check(const char *tablename, | |
69 | const void *entry, | |
70 | const struct xt_target *target, | |
71 | void *targetinfo, | |
72 | unsigned int hook_mask) | |
73 | { | |
74 | const struct ipt_ip *i = entry; | |
75 | ||
76 | if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) | |
77 | && !(i->invflags & IPT_INV_PROTO)) | |
78 | return true; | |
79 | ||
80 | pr_info("xt_TPROXY: Can be used only in combination with " | |
81 | "either -p tcp or -p udp\n"); | |
82 | return false; | |
83 | } | |
84 | ||
85 | static struct xt_target tproxy_tg_reg __read_mostly = { | |
86 | .name = "TPROXY", | |
87 | .family = AF_INET, | |
88 | .table = "mangle", | |
89 | .target = tproxy_tg, | |
90 | .targetsize = sizeof(struct xt_tproxy_target_info), | |
91 | .checkentry = tproxy_tg_check, | |
92 | .hooks = 1 << NF_INET_PRE_ROUTING, | |
93 | .me = THIS_MODULE, | |
94 | }; | |
95 | ||
96 | static int __init tproxy_tg_init(void) | |
97 | { | |
98 | nf_defrag_ipv4_enable(); | |
99 | return xt_register_target(&tproxy_tg_reg); | |
100 | } | |
101 | ||
102 | static void __exit tproxy_tg_exit(void) | |
103 | { | |
104 | xt_unregister_target(&tproxy_tg_reg); | |
105 | } | |
106 | ||
107 | module_init(tproxy_tg_init); | |
108 | module_exit(tproxy_tg_exit); | |
109 | MODULE_LICENSE("GPL"); | |
110 | MODULE_AUTHOR("Krisztian Kovacs"); | |
111 | MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module."); | |
112 | MODULE_ALIAS("ipt_TPROXY"); |