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136cdc71 KK |
1 | /* |
2 | * Transparent proxy support for Linux/iptables | |
3 | * | |
4 | * Copyright (C) 2007-2008 BalaBit IT Ltd. | |
5 | * Author: 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 |
136cdc71 KK |
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> | |
b64c9256 | 17 | #include <linux/netfilter_ipv6/ip6_tables.h> |
136cdc71 KK |
18 | #include <net/tcp.h> |
19 | #include <net/udp.h> | |
20 | #include <net/icmp.h> | |
21 | #include <net/sock.h> | |
22 | #include <net/inet_sock.h> | |
23 | #include <net/netfilter/nf_tproxy_core.h> | |
24 | #include <net/netfilter/ipv4/nf_defrag_ipv4.h> | |
b64c9256 | 25 | #include <net/netfilter/ipv6/nf_defrag_ipv6.h> |
136cdc71 | 26 | |
a31e1ffd LAT |
27 | #include <linux/netfilter/xt_socket.h> |
28 | ||
136cdc71 KK |
29 | #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) |
30 | #define XT_SOCKET_HAVE_CONNTRACK 1 | |
31 | #include <net/netfilter/nf_conntrack.h> | |
32 | #endif | |
33 | ||
34 | static int | |
b64c9256 | 35 | extract_icmp4_fields(const struct sk_buff *skb, |
136cdc71 KK |
36 | u8 *protocol, |
37 | __be32 *raddr, | |
38 | __be32 *laddr, | |
39 | __be16 *rport, | |
40 | __be16 *lport) | |
41 | { | |
42 | unsigned int outside_hdrlen = ip_hdrlen(skb); | |
43 | struct iphdr *inside_iph, _inside_iph; | |
44 | struct icmphdr *icmph, _icmph; | |
45 | __be16 *ports, _ports[2]; | |
46 | ||
47 | icmph = skb_header_pointer(skb, outside_hdrlen, | |
48 | sizeof(_icmph), &_icmph); | |
49 | if (icmph == NULL) | |
50 | return 1; | |
51 | ||
52 | switch (icmph->type) { | |
53 | case ICMP_DEST_UNREACH: | |
54 | case ICMP_SOURCE_QUENCH: | |
55 | case ICMP_REDIRECT: | |
56 | case ICMP_TIME_EXCEEDED: | |
57 | case ICMP_PARAMETERPROB: | |
58 | break; | |
59 | default: | |
60 | return 1; | |
61 | } | |
62 | ||
63 | inside_iph = skb_header_pointer(skb, outside_hdrlen + | |
64 | sizeof(struct icmphdr), | |
65 | sizeof(_inside_iph), &_inside_iph); | |
66 | if (inside_iph == NULL) | |
67 | return 1; | |
68 | ||
69 | if (inside_iph->protocol != IPPROTO_TCP && | |
70 | inside_iph->protocol != IPPROTO_UDP) | |
71 | return 1; | |
72 | ||
73 | ports = skb_header_pointer(skb, outside_hdrlen + | |
74 | sizeof(struct icmphdr) + | |
75 | (inside_iph->ihl << 2), | |
76 | sizeof(_ports), &_ports); | |
77 | if (ports == NULL) | |
78 | return 1; | |
79 | ||
80 | /* the inside IP packet is the one quoted from our side, thus | |
81 | * its saddr is the local address */ | |
82 | *protocol = inside_iph->protocol; | |
83 | *laddr = inside_iph->saddr; | |
84 | *lport = ports[0]; | |
85 | *raddr = inside_iph->daddr; | |
86 | *rport = ports[1]; | |
87 | ||
88 | return 0; | |
89 | } | |
90 | ||
136cdc71 | 91 | static bool |
62fc8051 | 92 | socket_match(const struct sk_buff *skb, struct xt_action_param *par, |
a31e1ffd | 93 | const struct xt_socket_mtinfo1 *info) |
136cdc71 KK |
94 | { |
95 | const struct iphdr *iph = ip_hdr(skb); | |
96 | struct udphdr _hdr, *hp = NULL; | |
97 | struct sock *sk; | |
98 | __be32 daddr, saddr; | |
99 | __be16 dport, sport; | |
100 | u8 protocol; | |
101 | #ifdef XT_SOCKET_HAVE_CONNTRACK | |
102 | struct nf_conn const *ct; | |
103 | enum ip_conntrack_info ctinfo; | |
104 | #endif | |
105 | ||
106 | if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) { | |
107 | hp = skb_header_pointer(skb, ip_hdrlen(skb), | |
108 | sizeof(_hdr), &_hdr); | |
109 | if (hp == NULL) | |
110 | return false; | |
111 | ||
112 | protocol = iph->protocol; | |
113 | saddr = iph->saddr; | |
114 | sport = hp->source; | |
115 | daddr = iph->daddr; | |
116 | dport = hp->dest; | |
117 | ||
118 | } else if (iph->protocol == IPPROTO_ICMP) { | |
b64c9256 | 119 | if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr, |
136cdc71 KK |
120 | &sport, &dport)) |
121 | return false; | |
122 | } else { | |
123 | return false; | |
124 | } | |
125 | ||
126 | #ifdef XT_SOCKET_HAVE_CONNTRACK | |
127 | /* Do the lookup with the original socket address in case this is a | |
128 | * reply packet of an established SNAT-ted connection. */ | |
129 | ||
130 | ct = nf_ct_get(skb, &ctinfo); | |
5bfddbd4 | 131 | if (ct && !nf_ct_is_untracked(ct) && |
136cdc71 KK |
132 | ((iph->protocol != IPPROTO_ICMP && |
133 | ctinfo == IP_CT_IS_REPLY + IP_CT_ESTABLISHED) || | |
134 | (iph->protocol == IPPROTO_ICMP && | |
135 | ctinfo == IP_CT_IS_REPLY + IP_CT_RELATED)) && | |
136 | (ct->status & IPS_SRC_NAT_DONE)) { | |
137 | ||
138 | daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip; | |
139 | dport = (iph->protocol == IPPROTO_TCP) ? | |
140 | ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port : | |
141 | ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port; | |
142 | } | |
143 | #endif | |
144 | ||
145 | sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol, | |
106e4c26 | 146 | saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY); |
136cdc71 | 147 | if (sk != NULL) { |
a31e1ffd LAT |
148 | bool wildcard; |
149 | bool transparent = true; | |
150 | ||
151 | /* Ignore sockets listening on INADDR_ANY */ | |
152 | wildcard = (sk->sk_state != TCP_TIME_WAIT && | |
c720c7e8 | 153 | inet_sk(sk)->inet_rcv_saddr == 0); |
a31e1ffd LAT |
154 | |
155 | /* Ignore non-transparent sockets, | |
156 | if XT_SOCKET_TRANSPARENT is used */ | |
157 | if (info && info->flags & XT_SOCKET_TRANSPARENT) | |
158 | transparent = ((sk->sk_state != TCP_TIME_WAIT && | |
159 | inet_sk(sk)->transparent) || | |
160 | (sk->sk_state == TCP_TIME_WAIT && | |
161 | inet_twsk(sk)->tw_transparent)); | |
136cdc71 KK |
162 | |
163 | nf_tproxy_put_sock(sk); | |
a31e1ffd LAT |
164 | |
165 | if (wildcard || !transparent) | |
136cdc71 KK |
166 | sk = NULL; |
167 | } | |
168 | ||
b64c9256 BS |
169 | pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n", |
170 | protocol, &saddr, ntohs(sport), | |
171 | &daddr, ntohs(dport), | |
172 | &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); | |
136cdc71 KK |
173 | |
174 | return (sk != NULL); | |
175 | } | |
176 | ||
a31e1ffd | 177 | static bool |
b64c9256 | 178 | socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par) |
a31e1ffd LAT |
179 | { |
180 | return socket_match(skb, par, NULL); | |
181 | } | |
182 | ||
183 | static bool | |
b64c9256 | 184 | socket_mt4_v1(const struct sk_buff *skb, struct xt_action_param *par) |
a31e1ffd LAT |
185 | { |
186 | return socket_match(skb, par, par->matchinfo); | |
187 | } | |
188 | ||
b64c9256 BS |
189 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
190 | ||
191 | static int | |
192 | extract_icmp6_fields(const struct sk_buff *skb, | |
193 | unsigned int outside_hdrlen, | |
194 | u8 *protocol, | |
195 | struct in6_addr **raddr, | |
196 | struct in6_addr **laddr, | |
197 | __be16 *rport, | |
198 | __be16 *lport) | |
199 | { | |
200 | struct ipv6hdr *inside_iph, _inside_iph; | |
201 | struct icmp6hdr *icmph, _icmph; | |
202 | __be16 *ports, _ports[2]; | |
203 | u8 inside_nexthdr; | |
204 | int inside_hdrlen; | |
205 | ||
206 | icmph = skb_header_pointer(skb, outside_hdrlen, | |
207 | sizeof(_icmph), &_icmph); | |
208 | if (icmph == NULL) | |
209 | return 1; | |
210 | ||
211 | if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK) | |
212 | return 1; | |
213 | ||
214 | inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph); | |
215 | if (inside_iph == NULL) | |
216 | return 1; | |
217 | inside_nexthdr = inside_iph->nexthdr; | |
218 | ||
219 | inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph), &inside_nexthdr); | |
220 | if (inside_hdrlen < 0) | |
221 | return 1; /* hjm: Packet has no/incomplete transport layer headers. */ | |
222 | ||
223 | if (inside_nexthdr != IPPROTO_TCP && | |
224 | inside_nexthdr != IPPROTO_UDP) | |
225 | return 1; | |
226 | ||
227 | ports = skb_header_pointer(skb, inside_hdrlen, | |
228 | sizeof(_ports), &_ports); | |
229 | if (ports == NULL) | |
230 | return 1; | |
231 | ||
232 | /* the inside IP packet is the one quoted from our side, thus | |
233 | * its saddr is the local address */ | |
234 | *protocol = inside_nexthdr; | |
235 | *laddr = &inside_iph->saddr; | |
236 | *lport = ports[0]; | |
237 | *raddr = &inside_iph->daddr; | |
238 | *rport = ports[1]; | |
239 | ||
240 | return 0; | |
241 | } | |
242 | ||
243 | static bool | |
244 | socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par) | |
245 | { | |
246 | struct ipv6hdr *iph = ipv6_hdr(skb); | |
247 | struct udphdr _hdr, *hp = NULL; | |
248 | struct sock *sk; | |
249 | struct in6_addr *daddr, *saddr; | |
250 | __be16 dport, sport; | |
251 | int thoff; | |
252 | u8 tproto; | |
253 | const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; | |
254 | ||
255 | tproto = ipv6_find_hdr(skb, &thoff, -1, NULL); | |
256 | if (tproto < 0) { | |
257 | pr_debug("unable to find transport header in IPv6 packet, dropping\n"); | |
258 | return NF_DROP; | |
259 | } | |
260 | ||
261 | if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) { | |
262 | hp = skb_header_pointer(skb, thoff, | |
263 | sizeof(_hdr), &_hdr); | |
264 | if (hp == NULL) | |
265 | return false; | |
266 | ||
267 | saddr = &iph->saddr; | |
268 | sport = hp->source; | |
269 | daddr = &iph->daddr; | |
270 | dport = hp->dest; | |
271 | ||
272 | } else if (tproto == IPPROTO_ICMPV6) { | |
273 | if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr, | |
274 | &sport, &dport)) | |
275 | return false; | |
276 | } else { | |
277 | return false; | |
278 | } | |
279 | ||
280 | sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto, | |
281 | saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY); | |
282 | if (sk != NULL) { | |
283 | bool wildcard; | |
284 | bool transparent = true; | |
285 | ||
286 | /* Ignore sockets listening on INADDR_ANY */ | |
287 | wildcard = (sk->sk_state != TCP_TIME_WAIT && | |
288 | ipv6_addr_any(&inet6_sk(sk)->rcv_saddr)); | |
289 | ||
290 | /* Ignore non-transparent sockets, | |
291 | if XT_SOCKET_TRANSPARENT is used */ | |
292 | if (info && info->flags & XT_SOCKET_TRANSPARENT) | |
293 | transparent = ((sk->sk_state != TCP_TIME_WAIT && | |
294 | inet_sk(sk)->transparent) || | |
295 | (sk->sk_state == TCP_TIME_WAIT && | |
296 | inet_twsk(sk)->tw_transparent)); | |
297 | ||
298 | nf_tproxy_put_sock(sk); | |
299 | ||
300 | if (wildcard || !transparent) | |
301 | sk = NULL; | |
302 | } | |
303 | ||
304 | pr_debug("proto %hhu %pI6:%hu -> %pI6:%hu " | |
305 | "(orig %pI6:%hu) sock %p\n", | |
306 | tproto, saddr, ntohs(sport), | |
307 | daddr, ntohs(dport), | |
308 | &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); | |
309 | ||
310 | return (sk != NULL); | |
311 | } | |
312 | #endif | |
313 | ||
a31e1ffd LAT |
314 | static struct xt_match socket_mt_reg[] __read_mostly = { |
315 | { | |
316 | .name = "socket", | |
317 | .revision = 0, | |
318 | .family = NFPROTO_IPV4, | |
b64c9256 | 319 | .match = socket_mt4_v0, |
aa3c487f JE |
320 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
321 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
322 | .me = THIS_MODULE, |
323 | }, | |
324 | { | |
325 | .name = "socket", | |
326 | .revision = 1, | |
327 | .family = NFPROTO_IPV4, | |
b64c9256 | 328 | .match = socket_mt4_v1, |
a31e1ffd | 329 | .matchsize = sizeof(struct xt_socket_mtinfo1), |
aa3c487f JE |
330 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
331 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
332 | .me = THIS_MODULE, |
333 | }, | |
b64c9256 BS |
334 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
335 | { | |
336 | .name = "socket", | |
337 | .revision = 1, | |
338 | .family = NFPROTO_IPV6, | |
339 | .match = socket_mt6_v1, | |
340 | .matchsize = sizeof(struct xt_socket_mtinfo1), | |
341 | .hooks = (1 << NF_INET_PRE_ROUTING) | | |
342 | (1 << NF_INET_LOCAL_IN), | |
343 | .me = THIS_MODULE, | |
344 | }, | |
345 | #endif | |
136cdc71 KK |
346 | }; |
347 | ||
348 | static int __init socket_mt_init(void) | |
349 | { | |
350 | nf_defrag_ipv4_enable(); | |
b64c9256 BS |
351 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
352 | nf_defrag_ipv6_enable(); | |
353 | #endif | |
354 | ||
a31e1ffd | 355 | return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
356 | } |
357 | ||
358 | static void __exit socket_mt_exit(void) | |
359 | { | |
a31e1ffd | 360 | xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
361 | } |
362 | ||
363 | module_init(socket_mt_init); | |
364 | module_exit(socket_mt_exit); | |
365 | ||
366 | MODULE_LICENSE("GPL"); | |
367 | MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler"); | |
368 | MODULE_DESCRIPTION("x_tables socket match module"); | |
369 | MODULE_ALIAS("ipt_socket"); | |
b64c9256 | 370 | MODULE_ALIAS("ip6t_socket"); |