]>
Commit | Line | Data |
---|---|---|
e8439270 KK |
1 | /* |
2 | * Transparent proxy support for Linux/iptables | |
3 | * | |
6ad78893 | 4 | * Copyright (c) 2006-2010 BalaBit IT Ltd. |
e8439270 KK |
5 | * Author: Balazs Scheidler, 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 |
e8439270 KK |
13 | #include <linux/module.h> |
14 | #include <linux/skbuff.h> | |
15 | #include <linux/ip.h> | |
16 | #include <net/checksum.h> | |
17 | #include <net/udp.h> | |
18 | #include <net/inet_sock.h> | |
cc6eb433 | 19 | #include <linux/inetdevice.h> |
e8439270 KK |
20 | #include <linux/netfilter/x_tables.h> |
21 | #include <linux/netfilter_ipv4/ip_tables.h> | |
e8439270 KK |
22 | |
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_TPROXY_HAVE_IPV6 1 | |
cc6eb433 BS |
27 | #include <net/if_inet6.h> |
28 | #include <net/addrconf.h> | |
29 | #include <linux/netfilter_ipv6/ip6_tables.h> | |
6ad78893 | 30 | #include <net/netfilter/ipv6/nf_defrag_ipv6.h> |
cc6eb433 BS |
31 | #endif |
32 | ||
e8439270 | 33 | #include <net/netfilter/nf_tproxy_core.h> |
cc6eb433 BS |
34 | #include <linux/netfilter/xt_TPROXY.h> |
35 | ||
36 | static inline __be32 | |
37 | tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr) | |
38 | { | |
39 | struct in_device *indev; | |
40 | __be32 laddr; | |
41 | ||
42 | if (user_laddr) | |
43 | return user_laddr; | |
44 | ||
45 | laddr = 0; | |
46 | rcu_read_lock(); | |
47 | indev = __in_dev_get_rcu(skb->dev); | |
48 | for_primary_ifa(indev) { | |
49 | laddr = ifa->ifa_local; | |
50 | break; | |
51 | } endfor_ifa(indev); | |
52 | rcu_read_unlock(); | |
53 | ||
54 | return laddr ? laddr : daddr; | |
55 | } | |
e8439270 | 56 | |
106e4c26 | 57 | /** |
6ad78893 | 58 | * tproxy_handle_time_wait4() - handle IPv4 TCP TIME_WAIT reopen redirections |
106e4c26 | 59 | * @skb: The skb being processed. |
6ad78893 BS |
60 | * @laddr: IPv4 address to redirect to or zero. |
61 | * @lport: TCP port to redirect to or zero. | |
106e4c26 BS |
62 | * @sk: The TIME_WAIT TCP socket found by the lookup. |
63 | * | |
64 | * We have to handle SYN packets arriving to TIME_WAIT sockets | |
65 | * differently: instead of reopening the connection we should rather | |
66 | * redirect the new connection to the proxy if there's a listener | |
67 | * socket present. | |
68 | * | |
6ad78893 | 69 | * tproxy_handle_time_wait4() consumes the socket reference passed in. |
106e4c26 BS |
70 | * |
71 | * Returns the listener socket if there's one, the TIME_WAIT socket if | |
72 | * no such listener is found, or NULL if the TCP header is incomplete. | |
73 | */ | |
74 | static struct sock * | |
6ad78893 BS |
75 | tproxy_handle_time_wait4(struct sk_buff *skb, __be32 laddr, __be16 lport, |
76 | struct sock *sk) | |
106e4c26 BS |
77 | { |
78 | const struct iphdr *iph = ip_hdr(skb); | |
106e4c26 BS |
79 | struct tcphdr _hdr, *hp; |
80 | ||
81 | hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); | |
82 | if (hp == NULL) { | |
83 | inet_twsk_put(inet_twsk(sk)); | |
84 | return NULL; | |
85 | } | |
86 | ||
87 | if (hp->syn && !hp->rst && !hp->ack && !hp->fin) { | |
88 | /* SYN to a TIME_WAIT socket, we'd rather redirect it | |
89 | * to a listener socket if there's one */ | |
90 | struct sock *sk2; | |
91 | ||
92 | sk2 = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol, | |
6ad78893 BS |
93 | iph->saddr, laddr ? laddr : iph->daddr, |
94 | hp->source, lport ? lport : hp->dest, | |
95 | skb->dev, NFT_LOOKUP_LISTENER); | |
96 | if (sk2) { | |
97 | inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row); | |
98 | inet_twsk_put(inet_twsk(sk)); | |
99 | sk = sk2; | |
100 | } | |
101 | } | |
102 | ||
103 | return sk; | |
104 | } | |
105 | ||
e8439270 | 106 | static unsigned int |
6ad78893 BS |
107 | tproxy_tg4(struct sk_buff *skb, __be32 laddr, __be16 lport, |
108 | u_int32_t mark_mask, u_int32_t mark_value) | |
e8439270 KK |
109 | { |
110 | const struct iphdr *iph = ip_hdr(skb); | |
e8439270 KK |
111 | struct udphdr _hdr, *hp; |
112 | struct sock *sk; | |
113 | ||
114 | hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); | |
115 | if (hp == NULL) | |
116 | return NF_DROP; | |
117 | ||
6ad78893 BS |
118 | /* check if there's an ongoing connection on the packet |
119 | * addresses, this happens if the redirect already happened | |
120 | * and the current packet belongs to an already established | |
121 | * connection */ | |
e8439270 | 122 | sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol, |
106e4c26 BS |
123 | iph->saddr, iph->daddr, |
124 | hp->source, hp->dest, | |
6ad78893 | 125 | skb->dev, NFT_LOOKUP_ESTABLISHED); |
106e4c26 | 126 | |
cc6eb433 BS |
127 | laddr = tproxy_laddr4(skb, laddr, iph->daddr); |
128 | if (!lport) | |
129 | lport = hp->dest; | |
130 | ||
106e4c26 BS |
131 | /* UDP has no TCP_TIME_WAIT state, so we never enter here */ |
132 | if (sk && sk->sk_state == TCP_TIME_WAIT) | |
6ad78893 BS |
133 | /* reopening a TIME_WAIT connection needs special handling */ |
134 | sk = tproxy_handle_time_wait4(skb, laddr, lport, sk); | |
106e4c26 | 135 | else if (!sk) |
6ad78893 BS |
136 | /* no, there's no established connection, check if |
137 | * there's a listener on the redirected addr/port */ | |
106e4c26 | 138 | sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol, |
cc6eb433 BS |
139 | iph->saddr, laddr, |
140 | hp->source, lport, | |
6ad78893 BS |
141 | skb->dev, NFT_LOOKUP_LISTENER); |
142 | ||
143 | /* NOTE: assign_sock consumes our sk reference */ | |
144 | if (sk && nf_tproxy_assign_sock(skb, sk)) { | |
145 | /* This should be in a separate target, but we don't do multiple | |
146 | targets on the same rule yet */ | |
147 | skb->mark = (skb->mark & ~mark_mask) ^ mark_value; | |
148 | ||
149 | pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n", | |
150 | iph->protocol, &iph->daddr, ntohs(hp->dest), | |
151 | &laddr, ntohs(lport), skb->mark); | |
152 | return NF_ACCEPT; | |
153 | } | |
154 | ||
cc6eb433 BS |
155 | pr_debug("no socket, dropping: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n", |
156 | iph->protocol, &iph->saddr, ntohs(hp->source), | |
157 | &iph->daddr, ntohs(hp->dest), skb->mark); | |
6ad78893 BS |
158 | return NF_DROP; |
159 | } | |
160 | ||
161 | static unsigned int | |
162 | tproxy_tg4_v0(struct sk_buff *skb, const struct xt_action_param *par) | |
163 | { | |
164 | const struct xt_tproxy_target_info *tgi = par->targinfo; | |
165 | ||
166 | return tproxy_tg4(skb, tgi->laddr, tgi->lport, tgi->mark_mask, tgi->mark_value); | |
167 | } | |
168 | ||
169 | static unsigned int | |
170 | tproxy_tg4_v1(struct sk_buff *skb, const struct xt_action_param *par) | |
171 | { | |
172 | const struct xt_tproxy_target_info_v1 *tgi = par->targinfo; | |
173 | ||
174 | return tproxy_tg4(skb, tgi->laddr.ip, tgi->lport, tgi->mark_mask, tgi->mark_value); | |
175 | } | |
176 | ||
f6318e55 | 177 | #ifdef XT_TPROXY_HAVE_IPV6 |
cc6eb433 BS |
178 | |
179 | static inline const struct in6_addr * | |
180 | tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr, | |
181 | const struct in6_addr *daddr) | |
182 | { | |
183 | struct inet6_dev *indev; | |
184 | struct inet6_ifaddr *ifa; | |
185 | struct in6_addr *laddr; | |
186 | ||
187 | if (!ipv6_addr_any(user_laddr)) | |
188 | return user_laddr; | |
189 | laddr = NULL; | |
190 | ||
191 | rcu_read_lock(); | |
192 | indev = __in6_dev_get(skb->dev); | |
193 | if (indev) | |
194 | list_for_each_entry(ifa, &indev->addr_list, if_list) { | |
195 | if (ifa->flags & (IFA_F_TENTATIVE | IFA_F_DEPRECATED)) | |
196 | continue; | |
197 | ||
198 | laddr = &ifa->addr; | |
199 | break; | |
200 | } | |
201 | rcu_read_unlock(); | |
202 | ||
203 | return laddr ? laddr : daddr; | |
204 | } | |
205 | ||
206 | /** | |
207 | * tproxy_handle_time_wait6() - handle IPv6 TCP TIME_WAIT reopen redirections | |
208 | * @skb: The skb being processed. | |
209 | * @tproto: Transport protocol. | |
210 | * @thoff: Transport protocol header offset. | |
211 | * @par: Iptables target parameters. | |
212 | * @sk: The TIME_WAIT TCP socket found by the lookup. | |
213 | * | |
214 | * We have to handle SYN packets arriving to TIME_WAIT sockets | |
215 | * differently: instead of reopening the connection we should rather | |
216 | * redirect the new connection to the proxy if there's a listener | |
217 | * socket present. | |
218 | * | |
219 | * tproxy_handle_time_wait6() consumes the socket reference passed in. | |
220 | * | |
221 | * Returns the listener socket if there's one, the TIME_WAIT socket if | |
222 | * no such listener is found, or NULL if the TCP header is incomplete. | |
223 | */ | |
224 | static struct sock * | |
225 | tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff, | |
226 | const struct xt_action_param *par, | |
227 | struct sock *sk) | |
228 | { | |
229 | const struct ipv6hdr *iph = ipv6_hdr(skb); | |
230 | struct tcphdr _hdr, *hp; | |
231 | const struct xt_tproxy_target_info_v1 *tgi = par->targinfo; | |
232 | ||
233 | hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr); | |
234 | if (hp == NULL) { | |
235 | inet_twsk_put(inet_twsk(sk)); | |
236 | return NULL; | |
237 | } | |
238 | ||
239 | if (hp->syn && !hp->rst && !hp->ack && !hp->fin) { | |
240 | /* SYN to a TIME_WAIT socket, we'd rather redirect it | |
241 | * to a listener socket if there's one */ | |
242 | struct sock *sk2; | |
243 | ||
244 | sk2 = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto, | |
245 | &iph->saddr, | |
246 | tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr), | |
247 | hp->source, | |
248 | tgi->lport ? tgi->lport : hp->dest, | |
249 | skb->dev, NFT_LOOKUP_LISTENER); | |
250 | if (sk2) { | |
251 | inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row); | |
252 | inet_twsk_put(inet_twsk(sk)); | |
253 | sk = sk2; | |
254 | } | |
255 | } | |
256 | ||
257 | return sk; | |
258 | } | |
259 | ||
6ad78893 BS |
260 | static unsigned int |
261 | tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par) | |
262 | { | |
263 | const struct ipv6hdr *iph = ipv6_hdr(skb); | |
264 | const struct xt_tproxy_target_info_v1 *tgi = par->targinfo; | |
265 | struct udphdr _hdr, *hp; | |
266 | struct sock *sk; | |
cc6eb433 BS |
267 | const struct in6_addr *laddr; |
268 | __be16 lport; | |
6ad78893 BS |
269 | int thoff; |
270 | int tproto; | |
271 | ||
272 | tproto = ipv6_find_hdr(skb, &thoff, -1, NULL); | |
273 | if (tproto < 0) { | |
274 | pr_debug("unable to find transport header in IPv6 packet, dropping\n"); | |
275 | return NF_DROP; | |
276 | } | |
277 | ||
278 | hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr); | |
279 | if (hp == NULL) { | |
280 | pr_debug("unable to grab transport header contents in IPv6 packet, dropping\n"); | |
281 | return NF_DROP; | |
282 | } | |
283 | ||
284 | /* check if there's an ongoing connection on the packet | |
285 | * addresses, this happens if the redirect already happened | |
286 | * and the current packet belongs to an already established | |
287 | * connection */ | |
288 | sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto, | |
289 | &iph->saddr, &iph->daddr, | |
290 | hp->source, hp->dest, | |
291 | par->in, NFT_LOOKUP_ESTABLISHED); | |
292 | ||
cc6eb433 BS |
293 | laddr = tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr); |
294 | lport = tgi->lport ? tgi->lport : hp->dest; | |
295 | ||
6ad78893 BS |
296 | /* UDP has no TCP_TIME_WAIT state, so we never enter here */ |
297 | if (sk && sk->sk_state == TCP_TIME_WAIT) | |
298 | /* reopening a TIME_WAIT connection needs special handling */ | |
299 | sk = tproxy_handle_time_wait6(skb, tproto, thoff, par, sk); | |
300 | else if (!sk) | |
301 | /* no there's no established connection, check if | |
302 | * there's a listener on the redirected addr/port */ | |
303 | sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto, | |
cc6eb433 BS |
304 | &iph->saddr, laddr, |
305 | hp->source, lport, | |
106e4c26 | 306 | par->in, NFT_LOOKUP_LISTENER); |
e8439270 KK |
307 | |
308 | /* NOTE: assign_sock consumes our sk reference */ | |
309 | if (sk && nf_tproxy_assign_sock(skb, sk)) { | |
310 | /* This should be in a separate target, but we don't do multiple | |
311 | targets on the same rule yet */ | |
312 | skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value; | |
313 | ||
6ad78893 | 314 | pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n", |
cc6eb433 BS |
315 | tproto, &iph->saddr, ntohs(hp->source), |
316 | laddr, ntohs(lport), skb->mark); | |
e8439270 KK |
317 | return NF_ACCEPT; |
318 | } | |
319 | ||
6ad78893 | 320 | pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n", |
cc6eb433 BS |
321 | tproto, &iph->saddr, ntohs(hp->source), |
322 | &iph->daddr, ntohs(hp->dest), skb->mark); | |
323 | ||
e8439270 KK |
324 | return NF_DROP; |
325 | } | |
326 | ||
6ad78893 BS |
327 | static int tproxy_tg6_check(const struct xt_tgchk_param *par) |
328 | { | |
329 | const struct ip6t_ip6 *i = par->entryinfo; | |
330 | ||
331 | if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) | |
332 | && !(i->flags & IP6T_INV_PROTO)) | |
333 | return 0; | |
334 | ||
335 | pr_info("Can be used only in combination with " | |
336 | "either -p tcp or -p udp\n"); | |
337 | return -EINVAL; | |
338 | } | |
339 | #endif | |
340 | ||
341 | static int tproxy_tg4_check(const struct xt_tgchk_param *par) | |
e8439270 | 342 | { |
af5d6dc2 | 343 | const struct ipt_ip *i = par->entryinfo; |
e8439270 KK |
344 | |
345 | if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) | |
346 | && !(i->invflags & IPT_INV_PROTO)) | |
d6b00a53 | 347 | return 0; |
e8439270 | 348 | |
ff67e4e4 | 349 | pr_info("Can be used only in combination with " |
e8439270 | 350 | "either -p tcp or -p udp\n"); |
d6b00a53 | 351 | return -EINVAL; |
e8439270 KK |
352 | } |
353 | ||
6ad78893 BS |
354 | static struct xt_target tproxy_tg_reg[] __read_mostly = { |
355 | { | |
356 | .name = "TPROXY", | |
357 | .family = NFPROTO_IPV4, | |
358 | .table = "mangle", | |
359 | .target = tproxy_tg4_v0, | |
360 | .revision = 0, | |
361 | .targetsize = sizeof(struct xt_tproxy_target_info), | |
362 | .checkentry = tproxy_tg4_check, | |
363 | .hooks = 1 << NF_INET_PRE_ROUTING, | |
364 | .me = THIS_MODULE, | |
365 | }, | |
366 | { | |
367 | .name = "TPROXY", | |
368 | .family = NFPROTO_IPV4, | |
369 | .table = "mangle", | |
370 | .target = tproxy_tg4_v1, | |
371 | .revision = 1, | |
372 | .targetsize = sizeof(struct xt_tproxy_target_info_v1), | |
373 | .checkentry = tproxy_tg4_check, | |
374 | .hooks = 1 << NF_INET_PRE_ROUTING, | |
375 | .me = THIS_MODULE, | |
376 | }, | |
f6318e55 | 377 | #ifdef XT_TPROXY_HAVE_IPV6 |
6ad78893 BS |
378 | { |
379 | .name = "TPROXY", | |
380 | .family = NFPROTO_IPV6, | |
381 | .table = "mangle", | |
382 | .target = tproxy_tg6_v1, | |
383 | .revision = 1, | |
384 | .targetsize = sizeof(struct xt_tproxy_target_info_v1), | |
385 | .checkentry = tproxy_tg6_check, | |
386 | .hooks = 1 << NF_INET_PRE_ROUTING, | |
387 | .me = THIS_MODULE, | |
388 | }, | |
389 | #endif | |
390 | ||
e8439270 KK |
391 | }; |
392 | ||
393 | static int __init tproxy_tg_init(void) | |
394 | { | |
395 | nf_defrag_ipv4_enable(); | |
f6318e55 | 396 | #ifdef XT_TPROXY_HAVE_IPV6 |
6ad78893 BS |
397 | nf_defrag_ipv6_enable(); |
398 | #endif | |
399 | ||
400 | return xt_register_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg)); | |
e8439270 KK |
401 | } |
402 | ||
403 | static void __exit tproxy_tg_exit(void) | |
404 | { | |
6ad78893 | 405 | xt_unregister_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg)); |
e8439270 KK |
406 | } |
407 | ||
408 | module_init(tproxy_tg_init); | |
409 | module_exit(tproxy_tg_exit); | |
410 | MODULE_LICENSE("GPL"); | |
6ad78893 | 411 | MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs"); |
e8439270 KK |
412 | MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module."); |
413 | MODULE_ALIAS("ipt_TPROXY"); | |
6ad78893 | 414 | MODULE_ALIAS("ip6t_TPROXY"); |