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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> | |
17 | #include <net/tcp.h> | |
18 | #include <net/udp.h> | |
19 | #include <net/icmp.h> | |
20 | #include <net/sock.h> | |
21 | #include <net/inet_sock.h> | |
22 | #include <net/netfilter/nf_tproxy_core.h> | |
23 | #include <net/netfilter/ipv4/nf_defrag_ipv4.h> | |
f6318e55 KK |
24 | |
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> | |
b64c9256 | 28 | #include <net/netfilter/ipv6/nf_defrag_ipv6.h> |
f6318e55 | 29 | #endif |
136cdc71 | 30 | |
a31e1ffd LAT |
31 | #include <linux/netfilter/xt_socket.h> |
32 | ||
136cdc71 KK |
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> | |
36 | #endif | |
37 | ||
d503b30b FW |
38 | static void |
39 | xt_socket_put_sk(struct sock *sk) | |
40 | { | |
41 | if (sk->sk_state == TCP_TIME_WAIT) | |
42 | inet_twsk_put(inet_twsk(sk)); | |
43 | else | |
44 | sock_put(sk); | |
45 | } | |
46 | ||
136cdc71 | 47 | static int |
b64c9256 | 48 | extract_icmp4_fields(const struct sk_buff *skb, |
136cdc71 KK |
49 | u8 *protocol, |
50 | __be32 *raddr, | |
51 | __be32 *laddr, | |
52 | __be16 *rport, | |
53 | __be16 *lport) | |
54 | { | |
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]; | |
59 | ||
60 | icmph = skb_header_pointer(skb, outside_hdrlen, | |
61 | sizeof(_icmph), &_icmph); | |
62 | if (icmph == NULL) | |
63 | return 1; | |
64 | ||
65 | switch (icmph->type) { | |
66 | case ICMP_DEST_UNREACH: | |
67 | case ICMP_SOURCE_QUENCH: | |
68 | case ICMP_REDIRECT: | |
69 | case ICMP_TIME_EXCEEDED: | |
70 | case ICMP_PARAMETERPROB: | |
71 | break; | |
72 | default: | |
73 | return 1; | |
74 | } | |
75 | ||
76 | inside_iph = skb_header_pointer(skb, outside_hdrlen + | |
77 | sizeof(struct icmphdr), | |
78 | sizeof(_inside_iph), &_inside_iph); | |
79 | if (inside_iph == NULL) | |
80 | return 1; | |
81 | ||
82 | if (inside_iph->protocol != IPPROTO_TCP && | |
83 | inside_iph->protocol != IPPROTO_UDP) | |
84 | return 1; | |
85 | ||
86 | ports = skb_header_pointer(skb, outside_hdrlen + | |
87 | sizeof(struct icmphdr) + | |
88 | (inside_iph->ihl << 2), | |
89 | sizeof(_ports), &_ports); | |
90 | if (ports == NULL) | |
91 | return 1; | |
92 | ||
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; | |
97 | *lport = ports[0]; | |
98 | *raddr = inside_iph->daddr; | |
99 | *rport = ports[1]; | |
100 | ||
101 | return 0; | |
102 | } | |
103 | ||
136cdc71 | 104 | static bool |
62fc8051 | 105 | socket_match(const struct sk_buff *skb, struct xt_action_param *par, |
a31e1ffd | 106 | const struct xt_socket_mtinfo1 *info) |
136cdc71 KK |
107 | { |
108 | const struct iphdr *iph = ip_hdr(skb); | |
109 | struct udphdr _hdr, *hp = NULL; | |
110 | struct sock *sk; | |
111 | __be32 daddr, saddr; | |
112 | __be16 dport, sport; | |
113 | u8 protocol; | |
114 | #ifdef XT_SOCKET_HAVE_CONNTRACK | |
115 | struct nf_conn const *ct; | |
116 | enum ip_conntrack_info ctinfo; | |
117 | #endif | |
118 | ||
119 | if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) { | |
120 | hp = skb_header_pointer(skb, ip_hdrlen(skb), | |
121 | sizeof(_hdr), &_hdr); | |
122 | if (hp == NULL) | |
123 | return false; | |
124 | ||
125 | protocol = iph->protocol; | |
126 | saddr = iph->saddr; | |
127 | sport = hp->source; | |
128 | daddr = iph->daddr; | |
129 | dport = hp->dest; | |
130 | ||
131 | } else if (iph->protocol == IPPROTO_ICMP) { | |
b64c9256 | 132 | if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr, |
136cdc71 KK |
133 | &sport, &dport)) |
134 | return false; | |
135 | } else { | |
136 | return false; | |
137 | } | |
138 | ||
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. */ | |
142 | ||
143 | ct = nf_ct_get(skb, &ctinfo); | |
5bfddbd4 | 144 | if (ct && !nf_ct_is_untracked(ct) && |
136cdc71 | 145 | ((iph->protocol != IPPROTO_ICMP && |
fb048833 | 146 | ctinfo == IP_CT_ESTABLISHED_REPLY) || |
136cdc71 | 147 | (iph->protocol == IPPROTO_ICMP && |
fb048833 | 148 | ctinfo == IP_CT_RELATED_REPLY)) && |
136cdc71 KK |
149 | (ct->status & IPS_SRC_NAT_DONE)) { |
150 | ||
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; | |
155 | } | |
156 | #endif | |
157 | ||
158 | sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol, | |
106e4c26 | 159 | saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY); |
136cdc71 | 160 | if (sk != NULL) { |
a31e1ffd LAT |
161 | bool wildcard; |
162 | bool transparent = true; | |
163 | ||
164 | /* Ignore sockets listening on INADDR_ANY */ | |
165 | wildcard = (sk->sk_state != TCP_TIME_WAIT && | |
c720c7e8 | 166 | inet_sk(sk)->inet_rcv_saddr == 0); |
a31e1ffd LAT |
167 | |
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)); | |
136cdc71 | 175 | |
d503b30b | 176 | xt_socket_put_sk(sk); |
a31e1ffd LAT |
177 | |
178 | if (wildcard || !transparent) | |
136cdc71 KK |
179 | sk = NULL; |
180 | } | |
181 | ||
b64c9256 BS |
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); | |
136cdc71 KK |
186 | |
187 | return (sk != NULL); | |
188 | } | |
189 | ||
a31e1ffd | 190 | static bool |
b64c9256 | 191 | socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par) |
a31e1ffd LAT |
192 | { |
193 | return socket_match(skb, par, NULL); | |
194 | } | |
195 | ||
196 | static bool | |
b64c9256 | 197 | socket_mt4_v1(const struct sk_buff *skb, struct xt_action_param *par) |
a31e1ffd LAT |
198 | { |
199 | return socket_match(skb, par, par->matchinfo); | |
200 | } | |
201 | ||
f6318e55 | 202 | #ifdef XT_SOCKET_HAVE_IPV6 |
b64c9256 BS |
203 | |
204 | static int | |
205 | extract_icmp6_fields(const struct sk_buff *skb, | |
206 | unsigned int outside_hdrlen, | |
089282fb | 207 | int *protocol, |
b64c9256 BS |
208 | struct in6_addr **raddr, |
209 | struct in6_addr **laddr, | |
210 | __be16 *rport, | |
211 | __be16 *lport) | |
212 | { | |
213 | struct ipv6hdr *inside_iph, _inside_iph; | |
214 | struct icmp6hdr *icmph, _icmph; | |
215 | __be16 *ports, _ports[2]; | |
216 | u8 inside_nexthdr; | |
75f2811c | 217 | __be16 inside_fragoff; |
b64c9256 BS |
218 | int inside_hdrlen; |
219 | ||
220 | icmph = skb_header_pointer(skb, outside_hdrlen, | |
221 | sizeof(_icmph), &_icmph); | |
222 | if (icmph == NULL) | |
223 | return 1; | |
224 | ||
225 | if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK) | |
226 | return 1; | |
227 | ||
228 | inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph); | |
229 | if (inside_iph == NULL) | |
230 | return 1; | |
231 | inside_nexthdr = inside_iph->nexthdr; | |
232 | ||
75f2811c JG |
233 | inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph), |
234 | &inside_nexthdr, &inside_fragoff); | |
b64c9256 BS |
235 | if (inside_hdrlen < 0) |
236 | return 1; /* hjm: Packet has no/incomplete transport layer headers. */ | |
237 | ||
238 | if (inside_nexthdr != IPPROTO_TCP && | |
239 | inside_nexthdr != IPPROTO_UDP) | |
240 | return 1; | |
241 | ||
242 | ports = skb_header_pointer(skb, inside_hdrlen, | |
243 | sizeof(_ports), &_ports); | |
244 | if (ports == NULL) | |
245 | return 1; | |
246 | ||
247 | /* the inside IP packet is the one quoted from our side, thus | |
248 | * its saddr is the local address */ | |
249 | *protocol = inside_nexthdr; | |
250 | *laddr = &inside_iph->saddr; | |
251 | *lport = ports[0]; | |
252 | *raddr = &inside_iph->daddr; | |
253 | *rport = ports[1]; | |
254 | ||
255 | return 0; | |
256 | } | |
257 | ||
258 | static bool | |
259 | socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par) | |
260 | { | |
261 | struct ipv6hdr *iph = ipv6_hdr(skb); | |
262 | struct udphdr _hdr, *hp = NULL; | |
263 | struct sock *sk; | |
264 | struct in6_addr *daddr, *saddr; | |
265 | __be16 dport, sport; | |
089282fb | 266 | int thoff, tproto; |
b64c9256 BS |
267 | const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; |
268 | ||
269 | tproto = ipv6_find_hdr(skb, &thoff, -1, NULL); | |
270 | if (tproto < 0) { | |
271 | pr_debug("unable to find transport header in IPv6 packet, dropping\n"); | |
272 | return NF_DROP; | |
273 | } | |
274 | ||
275 | if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) { | |
276 | hp = skb_header_pointer(skb, thoff, | |
277 | sizeof(_hdr), &_hdr); | |
278 | if (hp == NULL) | |
279 | return false; | |
280 | ||
281 | saddr = &iph->saddr; | |
282 | sport = hp->source; | |
283 | daddr = &iph->daddr; | |
284 | dport = hp->dest; | |
285 | ||
286 | } else if (tproto == IPPROTO_ICMPV6) { | |
287 | if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr, | |
288 | &sport, &dport)) | |
289 | return false; | |
290 | } else { | |
291 | return false; | |
292 | } | |
293 | ||
294 | sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto, | |
295 | saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY); | |
296 | if (sk != NULL) { | |
297 | bool wildcard; | |
298 | bool transparent = true; | |
299 | ||
300 | /* Ignore sockets listening on INADDR_ANY */ | |
301 | wildcard = (sk->sk_state != TCP_TIME_WAIT && | |
302 | ipv6_addr_any(&inet6_sk(sk)->rcv_saddr)); | |
303 | ||
304 | /* Ignore non-transparent sockets, | |
305 | if XT_SOCKET_TRANSPARENT is used */ | |
306 | if (info && info->flags & XT_SOCKET_TRANSPARENT) | |
307 | transparent = ((sk->sk_state != TCP_TIME_WAIT && | |
308 | inet_sk(sk)->transparent) || | |
309 | (sk->sk_state == TCP_TIME_WAIT && | |
310 | inet_twsk(sk)->tw_transparent)); | |
311 | ||
d503b30b | 312 | xt_socket_put_sk(sk); |
b64c9256 BS |
313 | |
314 | if (wildcard || !transparent) | |
315 | sk = NULL; | |
316 | } | |
317 | ||
089282fb | 318 | pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu " |
b64c9256 BS |
319 | "(orig %pI6:%hu) sock %p\n", |
320 | tproto, saddr, ntohs(sport), | |
321 | daddr, ntohs(dport), | |
322 | &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); | |
323 | ||
324 | return (sk != NULL); | |
325 | } | |
326 | #endif | |
327 | ||
a31e1ffd LAT |
328 | static struct xt_match socket_mt_reg[] __read_mostly = { |
329 | { | |
330 | .name = "socket", | |
331 | .revision = 0, | |
332 | .family = NFPROTO_IPV4, | |
b64c9256 | 333 | .match = socket_mt4_v0, |
aa3c487f JE |
334 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
335 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
336 | .me = THIS_MODULE, |
337 | }, | |
338 | { | |
339 | .name = "socket", | |
340 | .revision = 1, | |
341 | .family = NFPROTO_IPV4, | |
b64c9256 | 342 | .match = socket_mt4_v1, |
a31e1ffd | 343 | .matchsize = sizeof(struct xt_socket_mtinfo1), |
aa3c487f JE |
344 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
345 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
346 | .me = THIS_MODULE, |
347 | }, | |
f6318e55 | 348 | #ifdef XT_SOCKET_HAVE_IPV6 |
b64c9256 BS |
349 | { |
350 | .name = "socket", | |
351 | .revision = 1, | |
352 | .family = NFPROTO_IPV6, | |
353 | .match = socket_mt6_v1, | |
354 | .matchsize = sizeof(struct xt_socket_mtinfo1), | |
355 | .hooks = (1 << NF_INET_PRE_ROUTING) | | |
356 | (1 << NF_INET_LOCAL_IN), | |
357 | .me = THIS_MODULE, | |
358 | }, | |
359 | #endif | |
136cdc71 KK |
360 | }; |
361 | ||
362 | static int __init socket_mt_init(void) | |
363 | { | |
364 | nf_defrag_ipv4_enable(); | |
f6318e55 | 365 | #ifdef XT_SOCKET_HAVE_IPV6 |
b64c9256 BS |
366 | nf_defrag_ipv6_enable(); |
367 | #endif | |
368 | ||
a31e1ffd | 369 | return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
370 | } |
371 | ||
372 | static void __exit socket_mt_exit(void) | |
373 | { | |
a31e1ffd | 374 | xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
375 | } |
376 | ||
377 | module_init(socket_mt_init); | |
378 | module_exit(socket_mt_exit); | |
379 | ||
380 | MODULE_LICENSE("GPL"); | |
381 | MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler"); | |
382 | MODULE_DESCRIPTION("x_tables socket match module"); | |
383 | MODULE_ALIAS("ipt_socket"); | |
b64c9256 | 384 | MODULE_ALIAS("ip6t_socket"); |