Commit | Line | Data |
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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> | |
136cdc71 | 22 | #include <net/netfilter/ipv4/nf_defrag_ipv4.h> |
f6318e55 | 23 | |
c0cd1156 | 24 | #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
f6318e55 KK |
25 | #define XT_SOCKET_HAVE_IPV6 1 |
26 | #include <linux/netfilter_ipv6/ip6_tables.h> | |
93742cf8 | 27 | #include <net/inet6_hashtables.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 | ||
c0cd1156 | 33 | #if IS_ENABLED(CONFIG_NF_CONNTRACK) |
136cdc71 KK |
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 | ||
93742cf8 FW |
95 | /* "socket" match based redirection (no specific rule) |
96 | * =================================================== | |
97 | * | |
98 | * There are connections with dynamic endpoints (e.g. FTP data | |
99 | * connection) that the user is unable to add explicit rules | |
100 | * for. These are taken care of by a generic "socket" rule. It is | |
101 | * assumed that the proxy application is trusted to open such | |
102 | * connections without explicit iptables rule (except of course the | |
103 | * generic 'socket' rule). In this case the following sockets are | |
104 | * matched in preference order: | |
105 | * | |
106 | * - match: if there's a fully established connection matching the | |
107 | * _packet_ tuple | |
108 | * | |
109 | * - match: if there's a non-zero bound listener (possibly with a | |
110 | * non-local address) We don't accept zero-bound listeners, since | |
111 | * then local services could intercept traffic going through the | |
112 | * box. | |
113 | */ | |
114 | static struct sock * | |
115 | xt_socket_get_sock_v4(struct net *net, const u8 protocol, | |
116 | const __be32 saddr, const __be32 daddr, | |
117 | const __be16 sport, const __be16 dport, | |
118 | const struct net_device *in) | |
119 | { | |
120 | switch (protocol) { | |
121 | case IPPROTO_TCP: | |
122 | return __inet_lookup(net, &tcp_hashinfo, | |
123 | saddr, sport, daddr, dport, | |
124 | in->ifindex); | |
125 | case IPPROTO_UDP: | |
126 | return udp4_lib_lookup(net, saddr, sport, daddr, dport, | |
127 | in->ifindex); | |
128 | } | |
129 | return NULL; | |
130 | } | |
131 | ||
136cdc71 | 132 | static bool |
62fc8051 | 133 | socket_match(const struct sk_buff *skb, struct xt_action_param *par, |
a31e1ffd | 134 | const struct xt_socket_mtinfo1 *info) |
136cdc71 KK |
135 | { |
136 | const struct iphdr *iph = ip_hdr(skb); | |
137 | struct udphdr _hdr, *hp = NULL; | |
00028aa3 | 138 | struct sock *sk = skb->sk; |
6703aa74 PNA |
139 | __be32 uninitialized_var(daddr), uninitialized_var(saddr); |
140 | __be16 uninitialized_var(dport), uninitialized_var(sport); | |
141 | u8 uninitialized_var(protocol); | |
136cdc71 KK |
142 | #ifdef XT_SOCKET_HAVE_CONNTRACK |
143 | struct nf_conn const *ct; | |
144 | enum ip_conntrack_info ctinfo; | |
145 | #endif | |
146 | ||
147 | if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) { | |
148 | hp = skb_header_pointer(skb, ip_hdrlen(skb), | |
149 | sizeof(_hdr), &_hdr); | |
150 | if (hp == NULL) | |
151 | return false; | |
152 | ||
153 | protocol = iph->protocol; | |
154 | saddr = iph->saddr; | |
155 | sport = hp->source; | |
156 | daddr = iph->daddr; | |
157 | dport = hp->dest; | |
158 | ||
159 | } else if (iph->protocol == IPPROTO_ICMP) { | |
b64c9256 | 160 | if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr, |
136cdc71 KK |
161 | &sport, &dport)) |
162 | return false; | |
163 | } else { | |
164 | return false; | |
165 | } | |
166 | ||
167 | #ifdef XT_SOCKET_HAVE_CONNTRACK | |
168 | /* Do the lookup with the original socket address in case this is a | |
169 | * reply packet of an established SNAT-ted connection. */ | |
170 | ||
171 | ct = nf_ct_get(skb, &ctinfo); | |
5bfddbd4 | 172 | if (ct && !nf_ct_is_untracked(ct) && |
136cdc71 | 173 | ((iph->protocol != IPPROTO_ICMP && |
fb048833 | 174 | ctinfo == IP_CT_ESTABLISHED_REPLY) || |
136cdc71 | 175 | (iph->protocol == IPPROTO_ICMP && |
fb048833 | 176 | ctinfo == IP_CT_RELATED_REPLY)) && |
136cdc71 KK |
177 | (ct->status & IPS_SRC_NAT_DONE)) { |
178 | ||
179 | daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip; | |
180 | dport = (iph->protocol == IPPROTO_TCP) ? | |
181 | ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port : | |
182 | ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port; | |
183 | } | |
184 | #endif | |
185 | ||
00028aa3 | 186 | if (!sk) |
93742cf8 | 187 | sk = xt_socket_get_sock_v4(dev_net(skb->dev), protocol, |
00028aa3 | 188 | saddr, daddr, sport, dport, |
93742cf8 | 189 | par->in); |
00028aa3 | 190 | if (sk) { |
a31e1ffd LAT |
191 | bool wildcard; |
192 | bool transparent = true; | |
193 | ||
681f130f ED |
194 | /* Ignore sockets listening on INADDR_ANY, |
195 | * unless XT_SOCKET_NOWILDCARD is set | |
196 | */ | |
197 | wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) && | |
198 | sk->sk_state != TCP_TIME_WAIT && | |
c720c7e8 | 199 | inet_sk(sk)->inet_rcv_saddr == 0); |
a31e1ffd LAT |
200 | |
201 | /* Ignore non-transparent sockets, | |
202 | if XT_SOCKET_TRANSPARENT is used */ | |
baf60efa | 203 | if (info->flags & XT_SOCKET_TRANSPARENT) |
a31e1ffd LAT |
204 | transparent = ((sk->sk_state != TCP_TIME_WAIT && |
205 | inet_sk(sk)->transparent) || | |
206 | (sk->sk_state == TCP_TIME_WAIT && | |
207 | inet_twsk(sk)->tw_transparent)); | |
136cdc71 | 208 | |
00028aa3 | 209 | if (sk != skb->sk) |
1a8bf6ee | 210 | sock_gen_put(sk); |
a31e1ffd LAT |
211 | |
212 | if (wildcard || !transparent) | |
136cdc71 KK |
213 | sk = NULL; |
214 | } | |
215 | ||
b64c9256 BS |
216 | pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n", |
217 | protocol, &saddr, ntohs(sport), | |
218 | &daddr, ntohs(dport), | |
219 | &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); | |
136cdc71 KK |
220 | |
221 | return (sk != NULL); | |
222 | } | |
223 | ||
a31e1ffd | 224 | static bool |
b64c9256 | 225 | socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par) |
a31e1ffd | 226 | { |
baf60efa ED |
227 | static struct xt_socket_mtinfo1 xt_info_v0 = { |
228 | .flags = 0, | |
229 | }; | |
230 | ||
231 | return socket_match(skb, par, &xt_info_v0); | |
a31e1ffd LAT |
232 | } |
233 | ||
234 | static bool | |
681f130f | 235 | socket_mt4_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) |
a31e1ffd LAT |
236 | { |
237 | return socket_match(skb, par, par->matchinfo); | |
238 | } | |
239 | ||
f6318e55 | 240 | #ifdef XT_SOCKET_HAVE_IPV6 |
b64c9256 BS |
241 | |
242 | static int | |
243 | extract_icmp6_fields(const struct sk_buff *skb, | |
244 | unsigned int outside_hdrlen, | |
089282fb | 245 | int *protocol, |
b64c9256 BS |
246 | struct in6_addr **raddr, |
247 | struct in6_addr **laddr, | |
248 | __be16 *rport, | |
249 | __be16 *lport) | |
250 | { | |
251 | struct ipv6hdr *inside_iph, _inside_iph; | |
252 | struct icmp6hdr *icmph, _icmph; | |
253 | __be16 *ports, _ports[2]; | |
254 | u8 inside_nexthdr; | |
75f2811c | 255 | __be16 inside_fragoff; |
b64c9256 BS |
256 | int inside_hdrlen; |
257 | ||
258 | icmph = skb_header_pointer(skb, outside_hdrlen, | |
259 | sizeof(_icmph), &_icmph); | |
260 | if (icmph == NULL) | |
261 | return 1; | |
262 | ||
263 | if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK) | |
264 | return 1; | |
265 | ||
266 | inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph); | |
267 | if (inside_iph == NULL) | |
268 | return 1; | |
269 | inside_nexthdr = inside_iph->nexthdr; | |
270 | ||
75f2811c JG |
271 | inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph), |
272 | &inside_nexthdr, &inside_fragoff); | |
b64c9256 BS |
273 | if (inside_hdrlen < 0) |
274 | return 1; /* hjm: Packet has no/incomplete transport layer headers. */ | |
275 | ||
276 | if (inside_nexthdr != IPPROTO_TCP && | |
277 | inside_nexthdr != IPPROTO_UDP) | |
278 | return 1; | |
279 | ||
280 | ports = skb_header_pointer(skb, inside_hdrlen, | |
281 | sizeof(_ports), &_ports); | |
282 | if (ports == NULL) | |
283 | return 1; | |
284 | ||
285 | /* the inside IP packet is the one quoted from our side, thus | |
286 | * its saddr is the local address */ | |
287 | *protocol = inside_nexthdr; | |
288 | *laddr = &inside_iph->saddr; | |
289 | *lport = ports[0]; | |
290 | *raddr = &inside_iph->daddr; | |
291 | *rport = ports[1]; | |
292 | ||
293 | return 0; | |
294 | } | |
295 | ||
93742cf8 FW |
296 | static struct sock * |
297 | xt_socket_get_sock_v6(struct net *net, const u8 protocol, | |
298 | const struct in6_addr *saddr, const struct in6_addr *daddr, | |
299 | const __be16 sport, const __be16 dport, | |
300 | const struct net_device *in) | |
301 | { | |
302 | switch (protocol) { | |
303 | case IPPROTO_TCP: | |
304 | return inet6_lookup(net, &tcp_hashinfo, | |
305 | saddr, sport, daddr, dport, | |
306 | in->ifindex); | |
307 | case IPPROTO_UDP: | |
308 | return udp6_lib_lookup(net, saddr, sport, daddr, dport, | |
309 | in->ifindex); | |
310 | } | |
311 | ||
312 | return NULL; | |
313 | } | |
314 | ||
b64c9256 | 315 | static bool |
681f130f | 316 | socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) |
b64c9256 BS |
317 | { |
318 | struct ipv6hdr *iph = ipv6_hdr(skb); | |
319 | struct udphdr _hdr, *hp = NULL; | |
00028aa3 | 320 | struct sock *sk = skb->sk; |
6703aa74 PNA |
321 | struct in6_addr *daddr = NULL, *saddr = NULL; |
322 | __be16 uninitialized_var(dport), uninitialized_var(sport); | |
323 | int thoff = 0, uninitialized_var(tproto); | |
b64c9256 BS |
324 | const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; |
325 | ||
84018f55 | 326 | tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL); |
b64c9256 BS |
327 | if (tproto < 0) { |
328 | pr_debug("unable to find transport header in IPv6 packet, dropping\n"); | |
329 | return NF_DROP; | |
330 | } | |
331 | ||
332 | if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) { | |
333 | hp = skb_header_pointer(skb, thoff, | |
334 | sizeof(_hdr), &_hdr); | |
335 | if (hp == NULL) | |
336 | return false; | |
337 | ||
338 | saddr = &iph->saddr; | |
339 | sport = hp->source; | |
340 | daddr = &iph->daddr; | |
341 | dport = hp->dest; | |
342 | ||
343 | } else if (tproto == IPPROTO_ICMPV6) { | |
344 | if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr, | |
345 | &sport, &dport)) | |
346 | return false; | |
347 | } else { | |
348 | return false; | |
349 | } | |
350 | ||
00028aa3 | 351 | if (!sk) |
93742cf8 | 352 | sk = xt_socket_get_sock_v6(dev_net(skb->dev), tproto, |
00028aa3 | 353 | saddr, daddr, sport, dport, |
93742cf8 | 354 | par->in); |
00028aa3 | 355 | if (sk) { |
b64c9256 BS |
356 | bool wildcard; |
357 | bool transparent = true; | |
358 | ||
681f130f ED |
359 | /* Ignore sockets listening on INADDR_ANY |
360 | * unless XT_SOCKET_NOWILDCARD is set | |
361 | */ | |
362 | wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) && | |
363 | sk->sk_state != TCP_TIME_WAIT && | |
efe4208f | 364 | ipv6_addr_any(&sk->sk_v6_rcv_saddr)); |
b64c9256 BS |
365 | |
366 | /* Ignore non-transparent sockets, | |
367 | if XT_SOCKET_TRANSPARENT is used */ | |
baf60efa | 368 | if (info->flags & XT_SOCKET_TRANSPARENT) |
b64c9256 BS |
369 | transparent = ((sk->sk_state != TCP_TIME_WAIT && |
370 | inet_sk(sk)->transparent) || | |
371 | (sk->sk_state == TCP_TIME_WAIT && | |
372 | inet_twsk(sk)->tw_transparent)); | |
373 | ||
00028aa3 | 374 | if (sk != skb->sk) |
1a8bf6ee | 375 | sock_gen_put(sk); |
b64c9256 BS |
376 | |
377 | if (wildcard || !transparent) | |
378 | sk = NULL; | |
379 | } | |
380 | ||
089282fb | 381 | pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu " |
b64c9256 BS |
382 | "(orig %pI6:%hu) sock %p\n", |
383 | tproto, saddr, ntohs(sport), | |
384 | daddr, ntohs(dport), | |
385 | &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); | |
386 | ||
387 | return (sk != NULL); | |
388 | } | |
389 | #endif | |
390 | ||
681f130f ED |
391 | static int socket_mt_v1_check(const struct xt_mtchk_param *par) |
392 | { | |
393 | const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; | |
394 | ||
395 | if (info->flags & ~XT_SOCKET_FLAGS_V1) { | |
396 | pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V1); | |
397 | return -EINVAL; | |
398 | } | |
399 | return 0; | |
400 | } | |
401 | ||
402 | static int socket_mt_v2_check(const struct xt_mtchk_param *par) | |
403 | { | |
404 | const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo; | |
405 | ||
406 | if (info->flags & ~XT_SOCKET_FLAGS_V2) { | |
407 | pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V2); | |
408 | return -EINVAL; | |
409 | } | |
410 | return 0; | |
411 | } | |
412 | ||
a31e1ffd LAT |
413 | static struct xt_match socket_mt_reg[] __read_mostly = { |
414 | { | |
415 | .name = "socket", | |
416 | .revision = 0, | |
417 | .family = NFPROTO_IPV4, | |
b64c9256 | 418 | .match = socket_mt4_v0, |
aa3c487f JE |
419 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
420 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
421 | .me = THIS_MODULE, |
422 | }, | |
423 | { | |
424 | .name = "socket", | |
425 | .revision = 1, | |
426 | .family = NFPROTO_IPV4, | |
681f130f ED |
427 | .match = socket_mt4_v1_v2, |
428 | .checkentry = socket_mt_v1_check, | |
a31e1ffd | 429 | .matchsize = sizeof(struct xt_socket_mtinfo1), |
aa3c487f JE |
430 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
431 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
432 | .me = THIS_MODULE, |
433 | }, | |
f6318e55 | 434 | #ifdef XT_SOCKET_HAVE_IPV6 |
b64c9256 BS |
435 | { |
436 | .name = "socket", | |
437 | .revision = 1, | |
438 | .family = NFPROTO_IPV6, | |
681f130f ED |
439 | .match = socket_mt6_v1_v2, |
440 | .checkentry = socket_mt_v1_check, | |
441 | .matchsize = sizeof(struct xt_socket_mtinfo1), | |
442 | .hooks = (1 << NF_INET_PRE_ROUTING) | | |
443 | (1 << NF_INET_LOCAL_IN), | |
444 | .me = THIS_MODULE, | |
445 | }, | |
446 | #endif | |
447 | { | |
448 | .name = "socket", | |
449 | .revision = 2, | |
450 | .family = NFPROTO_IPV4, | |
451 | .match = socket_mt4_v1_v2, | |
452 | .checkentry = socket_mt_v2_check, | |
453 | .matchsize = sizeof(struct xt_socket_mtinfo1), | |
454 | .hooks = (1 << NF_INET_PRE_ROUTING) | | |
455 | (1 << NF_INET_LOCAL_IN), | |
456 | .me = THIS_MODULE, | |
457 | }, | |
458 | #ifdef XT_SOCKET_HAVE_IPV6 | |
459 | { | |
460 | .name = "socket", | |
461 | .revision = 2, | |
462 | .family = NFPROTO_IPV6, | |
463 | .match = socket_mt6_v1_v2, | |
464 | .checkentry = socket_mt_v2_check, | |
b64c9256 BS |
465 | .matchsize = sizeof(struct xt_socket_mtinfo1), |
466 | .hooks = (1 << NF_INET_PRE_ROUTING) | | |
467 | (1 << NF_INET_LOCAL_IN), | |
468 | .me = THIS_MODULE, | |
469 | }, | |
470 | #endif | |
136cdc71 KK |
471 | }; |
472 | ||
473 | static int __init socket_mt_init(void) | |
474 | { | |
475 | nf_defrag_ipv4_enable(); | |
f6318e55 | 476 | #ifdef XT_SOCKET_HAVE_IPV6 |
b64c9256 BS |
477 | nf_defrag_ipv6_enable(); |
478 | #endif | |
479 | ||
a31e1ffd | 480 | return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
481 | } |
482 | ||
483 | static void __exit socket_mt_exit(void) | |
484 | { | |
a31e1ffd | 485 | xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
486 | } |
487 | ||
488 | module_init(socket_mt_init); | |
489 | module_exit(socket_mt_exit); | |
490 | ||
491 | MODULE_LICENSE("GPL"); | |
492 | MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler"); | |
493 | MODULE_DESCRIPTION("x_tables socket match module"); | |
494 | MODULE_ALIAS("ipt_socket"); | |
b64c9256 | 495 | MODULE_ALIAS("ip6t_socket"); |