2 * Transparent proxy support for Linux/iptables
4 * Copyright (C) 2007-2008 BalaBit IT Ltd.
5 * Author: Krisztian Kovacs
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.
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
21 #include <net/inet_sock.h>
22 #include <net/netfilter/nf_tproxy_core.h>
23 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
25 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
26 #define XT_SOCKET_HAVE_IPV6 1
27 #include <linux/netfilter_ipv6/ip6_tables.h>
28 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
31 #include <linux/netfilter/xt_socket.h>
33 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
34 #define XT_SOCKET_HAVE_CONNTRACK 1
35 #include <net/netfilter/nf_conntrack.h>
39 xt_socket_put_sk(struct sock
*sk
)
41 if (sk
->sk_state
== TCP_TIME_WAIT
)
42 inet_twsk_put(inet_twsk(sk
));
48 extract_icmp4_fields(const struct sk_buff
*skb
,
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];
60 icmph
= skb_header_pointer(skb
, outside_hdrlen
,
61 sizeof(_icmph
), &_icmph
);
65 switch (icmph
->type
) {
66 case ICMP_DEST_UNREACH
:
67 case ICMP_SOURCE_QUENCH
:
69 case ICMP_TIME_EXCEEDED
:
70 case ICMP_PARAMETERPROB
:
76 inside_iph
= skb_header_pointer(skb
, outside_hdrlen
+
77 sizeof(struct icmphdr
),
78 sizeof(_inside_iph
), &_inside_iph
);
79 if (inside_iph
== NULL
)
82 if (inside_iph
->protocol
!= IPPROTO_TCP
&&
83 inside_iph
->protocol
!= IPPROTO_UDP
)
86 ports
= skb_header_pointer(skb
, outside_hdrlen
+
87 sizeof(struct icmphdr
) +
88 (inside_iph
->ihl
<< 2),
89 sizeof(_ports
), &_ports
);
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
;
98 *raddr
= inside_iph
->daddr
;
105 socket_match(const struct sk_buff
*skb
, struct xt_action_param
*par
,
106 const struct xt_socket_mtinfo1
*info
)
108 const struct iphdr
*iph
= ip_hdr(skb
);
109 struct udphdr _hdr
, *hp
= NULL
;
110 struct sock
*sk
= skb
->sk
;
111 __be32
uninitialized_var(daddr
), uninitialized_var(saddr
);
112 __be16
uninitialized_var(dport
), uninitialized_var(sport
);
113 u8
uninitialized_var(protocol
);
114 #ifdef XT_SOCKET_HAVE_CONNTRACK
115 struct nf_conn
const *ct
;
116 enum ip_conntrack_info ctinfo
;
119 if (iph
->protocol
== IPPROTO_UDP
|| iph
->protocol
== IPPROTO_TCP
) {
120 hp
= skb_header_pointer(skb
, ip_hdrlen(skb
),
121 sizeof(_hdr
), &_hdr
);
125 protocol
= iph
->protocol
;
131 } else if (iph
->protocol
== IPPROTO_ICMP
) {
132 if (extract_icmp4_fields(skb
, &protocol
, &saddr
, &daddr
,
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. */
143 ct
= nf_ct_get(skb
, &ctinfo
);
144 if (ct
&& !nf_ct_is_untracked(ct
) &&
145 ((iph
->protocol
!= IPPROTO_ICMP
&&
146 ctinfo
== IP_CT_ESTABLISHED_REPLY
) ||
147 (iph
->protocol
== IPPROTO_ICMP
&&
148 ctinfo
== IP_CT_RELATED_REPLY
)) &&
149 (ct
->status
& IPS_SRC_NAT_DONE
)) {
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
;
159 sk
= nf_tproxy_get_sock_v4(dev_net(skb
->dev
), protocol
,
160 saddr
, daddr
, sport
, dport
,
161 par
->in
, NFT_LOOKUP_ANY
);
164 bool transparent
= true;
166 /* Ignore sockets listening on INADDR_ANY,
167 * unless XT_SOCKET_NOWILDCARD is set
169 wildcard
= (!(info
->flags
& XT_SOCKET_NOWILDCARD
) &&
170 sk
->sk_state
!= TCP_TIME_WAIT
&&
171 inet_sk(sk
)->inet_rcv_saddr
== 0);
173 /* Ignore non-transparent sockets,
174 if XT_SOCKET_TRANSPARENT is used */
175 if (info
->flags
& XT_SOCKET_TRANSPARENT
)
176 transparent
= ((sk
->sk_state
!= TCP_TIME_WAIT
&&
177 inet_sk(sk
)->transparent
) ||
178 (sk
->sk_state
== TCP_TIME_WAIT
&&
179 inet_twsk(sk
)->tw_transparent
));
182 xt_socket_put_sk(sk
);
184 if (wildcard
|| !transparent
)
188 pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",
189 protocol
, &saddr
, ntohs(sport
),
190 &daddr
, ntohs(dport
),
191 &iph
->daddr
, hp
? ntohs(hp
->dest
) : 0, sk
);
197 socket_mt4_v0(const struct sk_buff
*skb
, struct xt_action_param
*par
)
199 static struct xt_socket_mtinfo1 xt_info_v0
= {
203 return socket_match(skb
, par
, &xt_info_v0
);
207 socket_mt4_v1_v2(const struct sk_buff
*skb
, struct xt_action_param
*par
)
209 return socket_match(skb
, par
, par
->matchinfo
);
212 #ifdef XT_SOCKET_HAVE_IPV6
215 extract_icmp6_fields(const struct sk_buff
*skb
,
216 unsigned int outside_hdrlen
,
218 struct in6_addr
**raddr
,
219 struct in6_addr
**laddr
,
223 struct ipv6hdr
*inside_iph
, _inside_iph
;
224 struct icmp6hdr
*icmph
, _icmph
;
225 __be16
*ports
, _ports
[2];
227 __be16 inside_fragoff
;
230 icmph
= skb_header_pointer(skb
, outside_hdrlen
,
231 sizeof(_icmph
), &_icmph
);
235 if (icmph
->icmp6_type
& ICMPV6_INFOMSG_MASK
)
238 inside_iph
= skb_header_pointer(skb
, outside_hdrlen
+ sizeof(_icmph
), sizeof(_inside_iph
), &_inside_iph
);
239 if (inside_iph
== NULL
)
241 inside_nexthdr
= inside_iph
->nexthdr
;
243 inside_hdrlen
= ipv6_skip_exthdr(skb
, outside_hdrlen
+ sizeof(_icmph
) + sizeof(_inside_iph
),
244 &inside_nexthdr
, &inside_fragoff
);
245 if (inside_hdrlen
< 0)
246 return 1; /* hjm: Packet has no/incomplete transport layer headers. */
248 if (inside_nexthdr
!= IPPROTO_TCP
&&
249 inside_nexthdr
!= IPPROTO_UDP
)
252 ports
= skb_header_pointer(skb
, inside_hdrlen
,
253 sizeof(_ports
), &_ports
);
257 /* the inside IP packet is the one quoted from our side, thus
258 * its saddr is the local address */
259 *protocol
= inside_nexthdr
;
260 *laddr
= &inside_iph
->saddr
;
262 *raddr
= &inside_iph
->daddr
;
269 socket_mt6_v1_v2(const struct sk_buff
*skb
, struct xt_action_param
*par
)
271 struct ipv6hdr
*iph
= ipv6_hdr(skb
);
272 struct udphdr _hdr
, *hp
= NULL
;
273 struct sock
*sk
= skb
->sk
;
274 struct in6_addr
*daddr
= NULL
, *saddr
= NULL
;
275 __be16
uninitialized_var(dport
), uninitialized_var(sport
);
276 int thoff
= 0, uninitialized_var(tproto
);
277 const struct xt_socket_mtinfo1
*info
= (struct xt_socket_mtinfo1
*) par
->matchinfo
;
279 tproto
= ipv6_find_hdr(skb
, &thoff
, -1, NULL
, NULL
);
281 pr_debug("unable to find transport header in IPv6 packet, dropping\n");
285 if (tproto
== IPPROTO_UDP
|| tproto
== IPPROTO_TCP
) {
286 hp
= skb_header_pointer(skb
, thoff
,
287 sizeof(_hdr
), &_hdr
);
296 } else if (tproto
== IPPROTO_ICMPV6
) {
297 if (extract_icmp6_fields(skb
, thoff
, &tproto
, &saddr
, &daddr
,
305 sk
= nf_tproxy_get_sock_v6(dev_net(skb
->dev
), tproto
,
306 saddr
, daddr
, sport
, dport
,
307 par
->in
, NFT_LOOKUP_ANY
);
310 bool transparent
= true;
312 /* Ignore sockets listening on INADDR_ANY
313 * unless XT_SOCKET_NOWILDCARD is set
315 wildcard
= (!(info
->flags
& XT_SOCKET_NOWILDCARD
) &&
316 sk
->sk_state
!= TCP_TIME_WAIT
&&
317 ipv6_addr_any(&inet6_sk(sk
)->rcv_saddr
));
319 /* Ignore non-transparent sockets,
320 if XT_SOCKET_TRANSPARENT is used */
321 if (info
->flags
& XT_SOCKET_TRANSPARENT
)
322 transparent
= ((sk
->sk_state
!= TCP_TIME_WAIT
&&
323 inet_sk(sk
)->transparent
) ||
324 (sk
->sk_state
== TCP_TIME_WAIT
&&
325 inet_twsk(sk
)->tw_transparent
));
328 xt_socket_put_sk(sk
);
330 if (wildcard
|| !transparent
)
334 pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "
335 "(orig %pI6:%hu) sock %p\n",
336 tproto
, saddr
, ntohs(sport
),
338 &iph
->daddr
, hp
? ntohs(hp
->dest
) : 0, sk
);
344 static int socket_mt_v1_check(const struct xt_mtchk_param
*par
)
346 const struct xt_socket_mtinfo1
*info
= (struct xt_socket_mtinfo1
*) par
->matchinfo
;
348 if (info
->flags
& ~XT_SOCKET_FLAGS_V1
) {
349 pr_info("unknown flags 0x%x\n", info
->flags
& ~XT_SOCKET_FLAGS_V1
);
355 static int socket_mt_v2_check(const struct xt_mtchk_param
*par
)
357 const struct xt_socket_mtinfo2
*info
= (struct xt_socket_mtinfo2
*) par
->matchinfo
;
359 if (info
->flags
& ~XT_SOCKET_FLAGS_V2
) {
360 pr_info("unknown flags 0x%x\n", info
->flags
& ~XT_SOCKET_FLAGS_V2
);
366 static struct xt_match socket_mt_reg
[] __read_mostly
= {
370 .family
= NFPROTO_IPV4
,
371 .match
= socket_mt4_v0
,
372 .hooks
= (1 << NF_INET_PRE_ROUTING
) |
373 (1 << NF_INET_LOCAL_IN
),
379 .family
= NFPROTO_IPV4
,
380 .match
= socket_mt4_v1_v2
,
381 .checkentry
= socket_mt_v1_check
,
382 .matchsize
= sizeof(struct xt_socket_mtinfo1
),
383 .hooks
= (1 << NF_INET_PRE_ROUTING
) |
384 (1 << NF_INET_LOCAL_IN
),
387 #ifdef XT_SOCKET_HAVE_IPV6
391 .family
= NFPROTO_IPV6
,
392 .match
= socket_mt6_v1_v2
,
393 .checkentry
= socket_mt_v1_check
,
394 .matchsize
= sizeof(struct xt_socket_mtinfo1
),
395 .hooks
= (1 << NF_INET_PRE_ROUTING
) |
396 (1 << NF_INET_LOCAL_IN
),
403 .family
= NFPROTO_IPV4
,
404 .match
= socket_mt4_v1_v2
,
405 .checkentry
= socket_mt_v2_check
,
406 .matchsize
= sizeof(struct xt_socket_mtinfo1
),
407 .hooks
= (1 << NF_INET_PRE_ROUTING
) |
408 (1 << NF_INET_LOCAL_IN
),
411 #ifdef XT_SOCKET_HAVE_IPV6
415 .family
= NFPROTO_IPV6
,
416 .match
= socket_mt6_v1_v2
,
417 .checkentry
= socket_mt_v2_check
,
418 .matchsize
= sizeof(struct xt_socket_mtinfo1
),
419 .hooks
= (1 << NF_INET_PRE_ROUTING
) |
420 (1 << NF_INET_LOCAL_IN
),
426 static int __init
socket_mt_init(void)
428 nf_defrag_ipv4_enable();
429 #ifdef XT_SOCKET_HAVE_IPV6
430 nf_defrag_ipv6_enable();
433 return xt_register_matches(socket_mt_reg
, ARRAY_SIZE(socket_mt_reg
));
436 static void __exit
socket_mt_exit(void)
438 xt_unregister_matches(socket_mt_reg
, ARRAY_SIZE(socket_mt_reg
));
441 module_init(socket_mt_init
);
442 module_exit(socket_mt_exit
);
444 MODULE_LICENSE("GPL");
445 MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
446 MODULE_DESCRIPTION("x_tables socket match module");
447 MODULE_ALIAS("ipt_socket");
448 MODULE_ALIAS("ip6t_socket");