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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 | */ | |
ff67e4e4 | 12 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
e8439270 KK |
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 | |
4b560b44 | 28 | tproxy_tg(struct sk_buff *skb, const struct xt_action_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, | |
116e1f1b CG |
40 | iph->saddr, |
41 | tgi->laddr ? tgi->laddr : iph->daddr, | |
42 | hp->source, | |
43 | tgi->lport ? tgi->lport : hp->dest, | |
7eb35586 | 44 | par->in, true); |
e8439270 KK |
45 | |
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; | |
51 | ||
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); | |
55 | return NF_ACCEPT; | |
56 | } | |
57 | ||
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); | |
61 | return NF_DROP; | |
62 | } | |
63 | ||
135367b8 | 64 | static int tproxy_tg_check(const struct xt_tgchk_param *par) |
e8439270 | 65 | { |
af5d6dc2 | 66 | const struct ipt_ip *i = par->entryinfo; |
e8439270 KK |
67 | |
68 | if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) | |
69 | && !(i->invflags & IPT_INV_PROTO)) | |
d6b00a53 | 70 | return 0; |
e8439270 | 71 | |
ff67e4e4 | 72 | pr_info("Can be used only in combination with " |
e8439270 | 73 | "either -p tcp or -p udp\n"); |
d6b00a53 | 74 | return -EINVAL; |
e8439270 KK |
75 | } |
76 | ||
77 | static struct xt_target tproxy_tg_reg __read_mostly = { | |
78 | .name = "TPROXY", | |
70a85166 | 79 | .family = NFPROTO_IPV4, |
e8439270 KK |
80 | .table = "mangle", |
81 | .target = tproxy_tg, | |
82 | .targetsize = sizeof(struct xt_tproxy_target_info), | |
83 | .checkentry = tproxy_tg_check, | |
84 | .hooks = 1 << NF_INET_PRE_ROUTING, | |
85 | .me = THIS_MODULE, | |
86 | }; | |
87 | ||
88 | static int __init tproxy_tg_init(void) | |
89 | { | |
90 | nf_defrag_ipv4_enable(); | |
91 | return xt_register_target(&tproxy_tg_reg); | |
92 | } | |
93 | ||
94 | static void __exit tproxy_tg_exit(void) | |
95 | { | |
96 | xt_unregister_target(&tproxy_tg_reg); | |
97 | } | |
98 | ||
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"); |