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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 | ||
38 | static int | |
b64c9256 | 39 | extract_icmp4_fields(const struct sk_buff *skb, |
136cdc71 KK |
40 | u8 *protocol, |
41 | __be32 *raddr, | |
42 | __be32 *laddr, | |
43 | __be16 *rport, | |
44 | __be16 *lport) | |
45 | { | |
46 | unsigned int outside_hdrlen = ip_hdrlen(skb); | |
47 | struct iphdr *inside_iph, _inside_iph; | |
48 | struct icmphdr *icmph, _icmph; | |
49 | __be16 *ports, _ports[2]; | |
50 | ||
51 | icmph = skb_header_pointer(skb, outside_hdrlen, | |
52 | sizeof(_icmph), &_icmph); | |
53 | if (icmph == NULL) | |
54 | return 1; | |
55 | ||
56 | switch (icmph->type) { | |
57 | case ICMP_DEST_UNREACH: | |
58 | case ICMP_SOURCE_QUENCH: | |
59 | case ICMP_REDIRECT: | |
60 | case ICMP_TIME_EXCEEDED: | |
61 | case ICMP_PARAMETERPROB: | |
62 | break; | |
63 | default: | |
64 | return 1; | |
65 | } | |
66 | ||
67 | inside_iph = skb_header_pointer(skb, outside_hdrlen + | |
68 | sizeof(struct icmphdr), | |
69 | sizeof(_inside_iph), &_inside_iph); | |
70 | if (inside_iph == NULL) | |
71 | return 1; | |
72 | ||
73 | if (inside_iph->protocol != IPPROTO_TCP && | |
74 | inside_iph->protocol != IPPROTO_UDP) | |
75 | return 1; | |
76 | ||
77 | ports = skb_header_pointer(skb, outside_hdrlen + | |
78 | sizeof(struct icmphdr) + | |
79 | (inside_iph->ihl << 2), | |
80 | sizeof(_ports), &_ports); | |
81 | if (ports == NULL) | |
82 | return 1; | |
83 | ||
84 | /* the inside IP packet is the one quoted from our side, thus | |
85 | * its saddr is the local address */ | |
86 | *protocol = inside_iph->protocol; | |
87 | *laddr = inside_iph->saddr; | |
88 | *lport = ports[0]; | |
89 | *raddr = inside_iph->daddr; | |
90 | *rport = ports[1]; | |
91 | ||
92 | return 0; | |
93 | } | |
94 | ||
136cdc71 | 95 | static bool |
62fc8051 | 96 | socket_match(const struct sk_buff *skb, struct xt_action_param *par, |
a31e1ffd | 97 | const struct xt_socket_mtinfo1 *info) |
136cdc71 KK |
98 | { |
99 | const struct iphdr *iph = ip_hdr(skb); | |
100 | struct udphdr _hdr, *hp = NULL; | |
101 | struct sock *sk; | |
102 | __be32 daddr, saddr; | |
103 | __be16 dport, sport; | |
104 | u8 protocol; | |
105 | #ifdef XT_SOCKET_HAVE_CONNTRACK | |
106 | struct nf_conn const *ct; | |
107 | enum ip_conntrack_info ctinfo; | |
108 | #endif | |
109 | ||
110 | if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) { | |
111 | hp = skb_header_pointer(skb, ip_hdrlen(skb), | |
112 | sizeof(_hdr), &_hdr); | |
113 | if (hp == NULL) | |
114 | return false; | |
115 | ||
116 | protocol = iph->protocol; | |
117 | saddr = iph->saddr; | |
118 | sport = hp->source; | |
119 | daddr = iph->daddr; | |
120 | dport = hp->dest; | |
121 | ||
122 | } else if (iph->protocol == IPPROTO_ICMP) { | |
b64c9256 | 123 | if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr, |
136cdc71 KK |
124 | &sport, &dport)) |
125 | return false; | |
126 | } else { | |
127 | return false; | |
128 | } | |
129 | ||
130 | #ifdef XT_SOCKET_HAVE_CONNTRACK | |
131 | /* Do the lookup with the original socket address in case this is a | |
132 | * reply packet of an established SNAT-ted connection. */ | |
133 | ||
134 | ct = nf_ct_get(skb, &ctinfo); | |
5bfddbd4 | 135 | if (ct && !nf_ct_is_untracked(ct) && |
136cdc71 KK |
136 | ((iph->protocol != IPPROTO_ICMP && |
137 | ctinfo == IP_CT_IS_REPLY + IP_CT_ESTABLISHED) || | |
138 | (iph->protocol == IPPROTO_ICMP && | |
139 | ctinfo == IP_CT_IS_REPLY + IP_CT_RELATED)) && | |
140 | (ct->status & IPS_SRC_NAT_DONE)) { | |
141 | ||
142 | daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip; | |
143 | dport = (iph->protocol == IPPROTO_TCP) ? | |
144 | ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port : | |
145 | ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port; | |
146 | } | |
147 | #endif | |
148 | ||
149 | sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol, | |
106e4c26 | 150 | saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY); |
136cdc71 | 151 | if (sk != NULL) { |
a31e1ffd LAT |
152 | bool wildcard; |
153 | bool transparent = true; | |
154 | ||
155 | /* Ignore sockets listening on INADDR_ANY */ | |
156 | wildcard = (sk->sk_state != TCP_TIME_WAIT && | |
c720c7e8 | 157 | inet_sk(sk)->inet_rcv_saddr == 0); |
a31e1ffd LAT |
158 | |
159 | /* Ignore non-transparent sockets, | |
160 | if XT_SOCKET_TRANSPARENT is used */ | |
161 | if (info && info->flags & XT_SOCKET_TRANSPARENT) | |
162 | transparent = ((sk->sk_state != TCP_TIME_WAIT && | |
163 | inet_sk(sk)->transparent) || | |
164 | (sk->sk_state == TCP_TIME_WAIT && | |
165 | inet_twsk(sk)->tw_transparent)); | |
136cdc71 KK |
166 | |
167 | nf_tproxy_put_sock(sk); | |
a31e1ffd LAT |
168 | |
169 | if (wildcard || !transparent) | |
136cdc71 KK |
170 | sk = NULL; |
171 | } | |
172 | ||
b64c9256 BS |
173 | pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n", |
174 | protocol, &saddr, ntohs(sport), | |
175 | &daddr, ntohs(dport), | |
176 | &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); | |
136cdc71 KK |
177 | |
178 | return (sk != NULL); | |
179 | } | |
180 | ||
a31e1ffd | 181 | static bool |
b64c9256 | 182 | socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par) |
a31e1ffd LAT |
183 | { |
184 | return socket_match(skb, par, NULL); | |
185 | } | |
186 | ||
187 | static bool | |
b64c9256 | 188 | socket_mt4_v1(const struct sk_buff *skb, struct xt_action_param *par) |
a31e1ffd LAT |
189 | { |
190 | return socket_match(skb, par, par->matchinfo); | |
191 | } | |
192 | ||
f6318e55 | 193 | #ifdef XT_SOCKET_HAVE_IPV6 |
b64c9256 BS |
194 | |
195 | static int | |
196 | extract_icmp6_fields(const struct sk_buff *skb, | |
197 | unsigned int outside_hdrlen, | |
089282fb | 198 | int *protocol, |
b64c9256 BS |
199 | struct in6_addr **raddr, |
200 | struct in6_addr **laddr, | |
201 | __be16 *rport, | |
202 | __be16 *lport) | |
203 | { | |
204 | struct ipv6hdr *inside_iph, _inside_iph; | |
205 | struct icmp6hdr *icmph, _icmph; | |
206 | __be16 *ports, _ports[2]; | |
207 | u8 inside_nexthdr; | |
208 | int inside_hdrlen; | |
209 | ||
210 | icmph = skb_header_pointer(skb, outside_hdrlen, | |
211 | sizeof(_icmph), &_icmph); | |
212 | if (icmph == NULL) | |
213 | return 1; | |
214 | ||
215 | if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK) | |
216 | return 1; | |
217 | ||
218 | inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph); | |
219 | if (inside_iph == NULL) | |
220 | return 1; | |
221 | inside_nexthdr = inside_iph->nexthdr; | |
222 | ||
223 | inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph), &inside_nexthdr); | |
224 | if (inside_hdrlen < 0) | |
225 | return 1; /* hjm: Packet has no/incomplete transport layer headers. */ | |
226 | ||
227 | if (inside_nexthdr != IPPROTO_TCP && | |
228 | inside_nexthdr != IPPROTO_UDP) | |
229 | return 1; | |
230 | ||
231 | ports = skb_header_pointer(skb, inside_hdrlen, | |
232 | sizeof(_ports), &_ports); | |
233 | if (ports == NULL) | |
234 | return 1; | |
235 | ||
236 | /* the inside IP packet is the one quoted from our side, thus | |
237 | * its saddr is the local address */ | |
238 | *protocol = inside_nexthdr; | |
239 | *laddr = &inside_iph->saddr; | |
240 | *lport = ports[0]; | |
241 | *raddr = &inside_iph->daddr; | |
242 | *rport = ports[1]; | |
243 | ||
244 | return 0; | |
245 | } | |
246 | ||
247 | static bool | |
248 | socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par) | |
249 | { | |
250 | struct ipv6hdr *iph = ipv6_hdr(skb); | |
251 | struct udphdr _hdr, *hp = NULL; | |
252 | struct sock *sk; | |
253 | struct in6_addr *daddr, *saddr; | |
254 | __be16 dport, sport; | |
089282fb | 255 | int thoff, tproto; |
b64c9256 BS |
256 | const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; |
257 | ||
258 | tproto = ipv6_find_hdr(skb, &thoff, -1, NULL); | |
259 | if (tproto < 0) { | |
260 | pr_debug("unable to find transport header in IPv6 packet, dropping\n"); | |
261 | return NF_DROP; | |
262 | } | |
263 | ||
264 | if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) { | |
265 | hp = skb_header_pointer(skb, thoff, | |
266 | sizeof(_hdr), &_hdr); | |
267 | if (hp == NULL) | |
268 | return false; | |
269 | ||
270 | saddr = &iph->saddr; | |
271 | sport = hp->source; | |
272 | daddr = &iph->daddr; | |
273 | dport = hp->dest; | |
274 | ||
275 | } else if (tproto == IPPROTO_ICMPV6) { | |
276 | if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr, | |
277 | &sport, &dport)) | |
278 | return false; | |
279 | } else { | |
280 | return false; | |
281 | } | |
282 | ||
283 | sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto, | |
284 | saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY); | |
285 | if (sk != NULL) { | |
286 | bool wildcard; | |
287 | bool transparent = true; | |
288 | ||
289 | /* Ignore sockets listening on INADDR_ANY */ | |
290 | wildcard = (sk->sk_state != TCP_TIME_WAIT && | |
291 | ipv6_addr_any(&inet6_sk(sk)->rcv_saddr)); | |
292 | ||
293 | /* Ignore non-transparent sockets, | |
294 | if XT_SOCKET_TRANSPARENT is used */ | |
295 | if (info && info->flags & XT_SOCKET_TRANSPARENT) | |
296 | transparent = ((sk->sk_state != TCP_TIME_WAIT && | |
297 | inet_sk(sk)->transparent) || | |
298 | (sk->sk_state == TCP_TIME_WAIT && | |
299 | inet_twsk(sk)->tw_transparent)); | |
300 | ||
301 | nf_tproxy_put_sock(sk); | |
302 | ||
303 | if (wildcard || !transparent) | |
304 | sk = NULL; | |
305 | } | |
306 | ||
089282fb | 307 | pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu " |
b64c9256 BS |
308 | "(orig %pI6:%hu) sock %p\n", |
309 | tproto, saddr, ntohs(sport), | |
310 | daddr, ntohs(dport), | |
311 | &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); | |
312 | ||
313 | return (sk != NULL); | |
314 | } | |
315 | #endif | |
316 | ||
a31e1ffd LAT |
317 | static struct xt_match socket_mt_reg[] __read_mostly = { |
318 | { | |
319 | .name = "socket", | |
320 | .revision = 0, | |
321 | .family = NFPROTO_IPV4, | |
b64c9256 | 322 | .match = socket_mt4_v0, |
aa3c487f JE |
323 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
324 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
325 | .me = THIS_MODULE, |
326 | }, | |
327 | { | |
328 | .name = "socket", | |
329 | .revision = 1, | |
330 | .family = NFPROTO_IPV4, | |
b64c9256 | 331 | .match = socket_mt4_v1, |
a31e1ffd | 332 | .matchsize = sizeof(struct xt_socket_mtinfo1), |
aa3c487f JE |
333 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
334 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
335 | .me = THIS_MODULE, |
336 | }, | |
f6318e55 | 337 | #ifdef XT_SOCKET_HAVE_IPV6 |
b64c9256 BS |
338 | { |
339 | .name = "socket", | |
340 | .revision = 1, | |
341 | .family = NFPROTO_IPV6, | |
342 | .match = socket_mt6_v1, | |
343 | .matchsize = sizeof(struct xt_socket_mtinfo1), | |
344 | .hooks = (1 << NF_INET_PRE_ROUTING) | | |
345 | (1 << NF_INET_LOCAL_IN), | |
346 | .me = THIS_MODULE, | |
347 | }, | |
348 | #endif | |
136cdc71 KK |
349 | }; |
350 | ||
351 | static int __init socket_mt_init(void) | |
352 | { | |
353 | nf_defrag_ipv4_enable(); | |
f6318e55 | 354 | #ifdef XT_SOCKET_HAVE_IPV6 |
b64c9256 BS |
355 | nf_defrag_ipv6_enable(); |
356 | #endif | |
357 | ||
a31e1ffd | 358 | return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
359 | } |
360 | ||
361 | static void __exit socket_mt_exit(void) | |
362 | { | |
a31e1ffd | 363 | xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
364 | } |
365 | ||
366 | module_init(socket_mt_init); | |
367 | module_exit(socket_mt_exit); | |
368 | ||
369 | MODULE_LICENSE("GPL"); | |
370 | MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler"); | |
371 | MODULE_DESCRIPTION("x_tables socket match module"); | |
372 | MODULE_ALIAS("ipt_socket"); | |
b64c9256 | 373 | MODULE_ALIAS("ip6t_socket"); |