2 * Transparent proxy support for Linux/iptables
4 * Copyright (C) 2007-2008 BalaBit IT Ltd.
5 * Author: 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>
15 #include <linux/netfilter/x_tables.h>
16 #include <linux/netfilter_ipv4/ip_tables.h>
21 #include <net/inet_sock.h>
22 #include <net/netfilter/nf_tproxy_core.h>
23 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
25 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
26 #define XT_SOCKET_HAVE_IPV6 1
27 #include <linux/netfilter_ipv6/ip6_tables.h>
28 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
31 #include <linux/netfilter/xt_socket.h>
33 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
34 #define XT_SOCKET_HAVE_CONNTRACK 1
35 #include <net/netfilter/nf_conntrack.h>
39 xt_socket_put_sk(struct sock *sk)
41 if (sk->sk_state == TCP_TIME_WAIT)
42 inet_twsk_put(inet_twsk(sk));
48 extract_icmp4_fields(const struct sk_buff *skb,
55 unsigned int outside_hdrlen = ip_hdrlen(skb);
56 struct iphdr *inside_iph, _inside_iph;
57 struct icmphdr *icmph, _icmph;
58 __be16 *ports, _ports[2];
60 icmph = skb_header_pointer(skb, outside_hdrlen,
61 sizeof(_icmph), &_icmph);
65 switch (icmph->type) {
66 case ICMP_DEST_UNREACH:
67 case ICMP_SOURCE_QUENCH:
69 case ICMP_TIME_EXCEEDED:
70 case ICMP_PARAMETERPROB:
76 inside_iph = skb_header_pointer(skb, outside_hdrlen +
77 sizeof(struct icmphdr),
78 sizeof(_inside_iph), &_inside_iph);
79 if (inside_iph == NULL)
82 if (inside_iph->protocol != IPPROTO_TCP &&
83 inside_iph->protocol != IPPROTO_UDP)
86 ports = skb_header_pointer(skb, outside_hdrlen +
87 sizeof(struct icmphdr) +
88 (inside_iph->ihl << 2),
89 sizeof(_ports), &_ports);
93 /* the inside IP packet is the one quoted from our side, thus
94 * its saddr is the local address */
95 *protocol = inside_iph->protocol;
96 *laddr = inside_iph->saddr;
98 *raddr = inside_iph->daddr;
105 socket_match(const struct sk_buff *skb, struct xt_action_param *par,
106 const struct xt_socket_mtinfo1 *info)
108 const struct iphdr *iph = ip_hdr(skb);
109 struct udphdr _hdr, *hp = NULL;
114 #ifdef XT_SOCKET_HAVE_CONNTRACK
115 struct nf_conn const *ct;
116 enum ip_conntrack_info ctinfo;
119 if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
120 hp = skb_header_pointer(skb, ip_hdrlen(skb),
121 sizeof(_hdr), &_hdr);
125 protocol = iph->protocol;
131 } else if (iph->protocol == IPPROTO_ICMP) {
132 if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
139 #ifdef XT_SOCKET_HAVE_CONNTRACK
140 /* Do the lookup with the original socket address in case this is a
141 * reply packet of an established SNAT-ted connection. */
143 ct = nf_ct_get(skb, &ctinfo);
144 if (ct && !nf_ct_is_untracked(ct) &&
145 ((iph->protocol != IPPROTO_ICMP &&
146 ctinfo == IP_CT_ESTABLISHED_REPLY) ||
147 (iph->protocol == IPPROTO_ICMP &&
148 ctinfo == IP_CT_RELATED_REPLY)) &&
149 (ct->status & IPS_SRC_NAT_DONE)) {
151 daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
152 dport = (iph->protocol == IPPROTO_TCP) ?
153 ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
154 ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
158 sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol,
159 saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY);
162 bool transparent = true;
164 /* Ignore sockets listening on INADDR_ANY */
165 wildcard = (sk->sk_state != TCP_TIME_WAIT &&
166 inet_sk(sk)->inet_rcv_saddr == 0);
168 /* Ignore non-transparent sockets,
169 if XT_SOCKET_TRANSPARENT is used */
170 if (info && info->flags & XT_SOCKET_TRANSPARENT)
171 transparent = ((sk->sk_state != TCP_TIME_WAIT &&
172 inet_sk(sk)->transparent) ||
173 (sk->sk_state == TCP_TIME_WAIT &&
174 inet_twsk(sk)->tw_transparent));
176 xt_socket_put_sk(sk);
178 if (wildcard || !transparent)
182 pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",
183 protocol, &saddr, ntohs(sport),
184 &daddr, ntohs(dport),
185 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
191 socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par)
193 return socket_match(skb, par, NULL);
197 socket_mt4_v1(const struct sk_buff *skb, struct xt_action_param *par)
199 return socket_match(skb, par, par->matchinfo);
202 #ifdef XT_SOCKET_HAVE_IPV6
205 extract_icmp6_fields(const struct sk_buff *skb,
206 unsigned int outside_hdrlen,
208 const struct in6_addr **raddr,
209 const struct in6_addr **laddr,
212 struct ipv6hdr *ipv6_var)
214 const struct ipv6hdr *inside_iph;
215 struct icmp6hdr *icmph, _icmph;
216 __be16 *ports, _ports[2];
220 icmph = skb_header_pointer(skb, outside_hdrlen,
221 sizeof(_icmph), &_icmph);
225 if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK)
228 inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph),
229 sizeof(*ipv6_var), ipv6_var);
230 if (inside_iph == NULL)
232 inside_nexthdr = inside_iph->nexthdr;
234 inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) +
237 if (inside_hdrlen < 0)
238 return 1; /* hjm: Packet has no/incomplete transport layer headers. */
240 if (inside_nexthdr != IPPROTO_TCP &&
241 inside_nexthdr != IPPROTO_UDP)
244 ports = skb_header_pointer(skb, inside_hdrlen,
245 sizeof(_ports), &_ports);
249 /* the inside IP packet is the one quoted from our side, thus
250 * its saddr is the local address */
251 *protocol = inside_nexthdr;
252 *laddr = &inside_iph->saddr;
254 *raddr = &inside_iph->daddr;
261 socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par)
263 struct ipv6hdr ipv6_var, *iph = ipv6_hdr(skb);
264 struct udphdr _hdr, *hp = NULL;
266 const struct in6_addr *daddr, *saddr;
269 const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
271 tproto = ipv6_find_hdr(skb, &thoff, -1, NULL);
273 pr_debug("unable to find transport header in IPv6 packet, dropping\n");
277 if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {
278 hp = skb_header_pointer(skb, thoff,
279 sizeof(_hdr), &_hdr);
288 } else if (tproto == IPPROTO_ICMPV6) {
289 if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
290 &sport, &dport, &ipv6_var))
296 sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
297 saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY);
300 bool transparent = true;
302 /* Ignore sockets listening on INADDR_ANY */
303 wildcard = (sk->sk_state != TCP_TIME_WAIT &&
304 ipv6_addr_any(&inet6_sk(sk)->rcv_saddr));
306 /* Ignore non-transparent sockets,
307 if XT_SOCKET_TRANSPARENT is used */
308 if (info && info->flags & XT_SOCKET_TRANSPARENT)
309 transparent = ((sk->sk_state != TCP_TIME_WAIT &&
310 inet_sk(sk)->transparent) ||
311 (sk->sk_state == TCP_TIME_WAIT &&
312 inet_twsk(sk)->tw_transparent));
314 xt_socket_put_sk(sk);
316 if (wildcard || !transparent)
320 pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "
321 "(orig %pI6:%hu) sock %p\n",
322 tproto, saddr, ntohs(sport),
324 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
330 static struct xt_match socket_mt_reg[] __read_mostly = {
334 .family = NFPROTO_IPV4,
335 .match = socket_mt4_v0,
336 .hooks = (1 << NF_INET_PRE_ROUTING) |
337 (1 << NF_INET_LOCAL_IN),
343 .family = NFPROTO_IPV4,
344 .match = socket_mt4_v1,
345 .matchsize = sizeof(struct xt_socket_mtinfo1),
346 .hooks = (1 << NF_INET_PRE_ROUTING) |
347 (1 << NF_INET_LOCAL_IN),
350 #ifdef XT_SOCKET_HAVE_IPV6
354 .family = NFPROTO_IPV6,
355 .match = socket_mt6_v1,
356 .matchsize = sizeof(struct xt_socket_mtinfo1),
357 .hooks = (1 << NF_INET_PRE_ROUTING) |
358 (1 << NF_INET_LOCAL_IN),
364 static int __init socket_mt_init(void)
366 nf_defrag_ipv4_enable();
367 #ifdef XT_SOCKET_HAVE_IPV6
368 nf_defrag_ipv6_enable();
371 return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
374 static void __exit socket_mt_exit(void)
376 xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
379 module_init(socket_mt_init);
380 module_exit(socket_mt_exit);
382 MODULE_LICENSE("GPL");
383 MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
384 MODULE_DESCRIPTION("x_tables socket match module");
385 MODULE_ALIAS("ipt_socket");
386 MODULE_ALIAS("ip6t_socket");