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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 | |
7eb35586 | 28 | tproxy_tg(struct sk_buff *skb, const struct xt_target_param *par) |
e8439270 KK |
29 | { |
30 | const struct iphdr *iph = ip_hdr(skb); | |
7eb35586 | 31 | const struct xt_tproxy_target_info *tgi = par->targinfo; |
e8439270 KK |
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, | |
7eb35586 | 42 | par->in, true); |
e8439270 KK |
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 | ||
af5d6dc2 | 62 | static bool tproxy_tg_check(const struct xt_tgchk_param *par) |
e8439270 | 63 | { |
af5d6dc2 | 64 | const struct ipt_ip *i = par->entryinfo; |
e8439270 KK |
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 | ||
75 | static 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 | ||
86 | static int __init tproxy_tg_init(void) | |
87 | { | |
88 | nf_defrag_ipv4_enable(); | |
89 | return xt_register_target(&tproxy_tg_reg); | |
90 | } | |
91 | ||
92 | static void __exit tproxy_tg_exit(void) | |
93 | { | |
94 | xt_unregister_target(&tproxy_tg_reg); | |
95 | } | |
96 | ||
97 | module_init(tproxy_tg_init); | |
98 | module_exit(tproxy_tg_exit); | |
99 | MODULE_LICENSE("GPL"); | |
100 | MODULE_AUTHOR("Krisztian Kovacs"); | |
101 | MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module."); | |
102 | MODULE_ALIAS("ipt_TPROXY"); |