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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 | */ | |
12 | ||
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> | |
24 | ||
a31e1ffd LAT |
25 | #include <linux/netfilter/xt_socket.h> |
26 | ||
136cdc71 KK |
27 | #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) |
28 | #define XT_SOCKET_HAVE_CONNTRACK 1 | |
29 | #include <net/netfilter/nf_conntrack.h> | |
30 | #endif | |
31 | ||
32 | static int | |
33 | extract_icmp_fields(const struct sk_buff *skb, | |
34 | u8 *protocol, | |
35 | __be32 *raddr, | |
36 | __be32 *laddr, | |
37 | __be16 *rport, | |
38 | __be16 *lport) | |
39 | { | |
40 | unsigned int outside_hdrlen = ip_hdrlen(skb); | |
41 | struct iphdr *inside_iph, _inside_iph; | |
42 | struct icmphdr *icmph, _icmph; | |
43 | __be16 *ports, _ports[2]; | |
44 | ||
45 | icmph = skb_header_pointer(skb, outside_hdrlen, | |
46 | sizeof(_icmph), &_icmph); | |
47 | if (icmph == NULL) | |
48 | return 1; | |
49 | ||
50 | switch (icmph->type) { | |
51 | case ICMP_DEST_UNREACH: | |
52 | case ICMP_SOURCE_QUENCH: | |
53 | case ICMP_REDIRECT: | |
54 | case ICMP_TIME_EXCEEDED: | |
55 | case ICMP_PARAMETERPROB: | |
56 | break; | |
57 | default: | |
58 | return 1; | |
59 | } | |
60 | ||
61 | inside_iph = skb_header_pointer(skb, outside_hdrlen + | |
62 | sizeof(struct icmphdr), | |
63 | sizeof(_inside_iph), &_inside_iph); | |
64 | if (inside_iph == NULL) | |
65 | return 1; | |
66 | ||
67 | if (inside_iph->protocol != IPPROTO_TCP && | |
68 | inside_iph->protocol != IPPROTO_UDP) | |
69 | return 1; | |
70 | ||
71 | ports = skb_header_pointer(skb, outside_hdrlen + | |
72 | sizeof(struct icmphdr) + | |
73 | (inside_iph->ihl << 2), | |
74 | sizeof(_ports), &_ports); | |
75 | if (ports == NULL) | |
76 | return 1; | |
77 | ||
78 | /* the inside IP packet is the one quoted from our side, thus | |
79 | * its saddr is the local address */ | |
80 | *protocol = inside_iph->protocol; | |
81 | *laddr = inside_iph->saddr; | |
82 | *lport = ports[0]; | |
83 | *raddr = inside_iph->daddr; | |
84 | *rport = ports[1]; | |
85 | ||
86 | return 0; | |
87 | } | |
88 | ||
89 | ||
90 | static bool | |
a31e1ffd LAT |
91 | socket_match(const struct sk_buff *skb, const struct xt_match_param *par, |
92 | const struct xt_socket_mtinfo1 *info) | |
136cdc71 KK |
93 | { |
94 | const struct iphdr *iph = ip_hdr(skb); | |
95 | struct udphdr _hdr, *hp = NULL; | |
96 | struct sock *sk; | |
97 | __be32 daddr, saddr; | |
98 | __be16 dport, sport; | |
99 | u8 protocol; | |
100 | #ifdef XT_SOCKET_HAVE_CONNTRACK | |
101 | struct nf_conn const *ct; | |
102 | enum ip_conntrack_info ctinfo; | |
103 | #endif | |
104 | ||
105 | if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) { | |
106 | hp = skb_header_pointer(skb, ip_hdrlen(skb), | |
107 | sizeof(_hdr), &_hdr); | |
108 | if (hp == NULL) | |
109 | return false; | |
110 | ||
111 | protocol = iph->protocol; | |
112 | saddr = iph->saddr; | |
113 | sport = hp->source; | |
114 | daddr = iph->daddr; | |
115 | dport = hp->dest; | |
116 | ||
117 | } else if (iph->protocol == IPPROTO_ICMP) { | |
118 | if (extract_icmp_fields(skb, &protocol, &saddr, &daddr, | |
119 | &sport, &dport)) | |
120 | return false; | |
121 | } else { | |
122 | return false; | |
123 | } | |
124 | ||
125 | #ifdef XT_SOCKET_HAVE_CONNTRACK | |
126 | /* Do the lookup with the original socket address in case this is a | |
127 | * reply packet of an established SNAT-ted connection. */ | |
128 | ||
129 | ct = nf_ct_get(skb, &ctinfo); | |
130 | if (ct && (ct != &nf_conntrack_untracked) && | |
131 | ((iph->protocol != IPPROTO_ICMP && | |
132 | ctinfo == IP_CT_IS_REPLY + IP_CT_ESTABLISHED) || | |
133 | (iph->protocol == IPPROTO_ICMP && | |
134 | ctinfo == IP_CT_IS_REPLY + IP_CT_RELATED)) && | |
135 | (ct->status & IPS_SRC_NAT_DONE)) { | |
136 | ||
137 | daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip; | |
138 | dport = (iph->protocol == IPPROTO_TCP) ? | |
139 | ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port : | |
140 | ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port; | |
141 | } | |
142 | #endif | |
143 | ||
144 | sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol, | |
f7108a20 | 145 | saddr, daddr, sport, dport, par->in, false); |
136cdc71 | 146 | if (sk != NULL) { |
a31e1ffd LAT |
147 | bool wildcard; |
148 | bool transparent = true; | |
149 | ||
150 | /* Ignore sockets listening on INADDR_ANY */ | |
151 | wildcard = (sk->sk_state != TCP_TIME_WAIT && | |
c720c7e8 | 152 | inet_sk(sk)->inet_rcv_saddr == 0); |
a31e1ffd LAT |
153 | |
154 | /* Ignore non-transparent sockets, | |
155 | if XT_SOCKET_TRANSPARENT is used */ | |
156 | if (info && info->flags & XT_SOCKET_TRANSPARENT) | |
157 | transparent = ((sk->sk_state != TCP_TIME_WAIT && | |
158 | inet_sk(sk)->transparent) || | |
159 | (sk->sk_state == TCP_TIME_WAIT && | |
160 | inet_twsk(sk)->tw_transparent)); | |
136cdc71 KK |
161 | |
162 | nf_tproxy_put_sock(sk); | |
a31e1ffd LAT |
163 | |
164 | if (wildcard || !transparent) | |
136cdc71 KK |
165 | sk = NULL; |
166 | } | |
167 | ||
168 | pr_debug("socket match: proto %u %08x:%u -> %08x:%u " | |
169 | "(orig %08x:%u) sock %p\n", | |
170 | protocol, ntohl(saddr), ntohs(sport), | |
171 | ntohl(daddr), ntohs(dport), | |
172 | ntohl(iph->daddr), hp ? ntohs(hp->dest) : 0, sk); | |
173 | ||
174 | return (sk != NULL); | |
175 | } | |
176 | ||
a31e1ffd LAT |
177 | static bool |
178 | socket_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par) | |
179 | { | |
180 | return socket_match(skb, par, NULL); | |
181 | } | |
182 | ||
183 | static bool | |
184 | socket_mt_v1(const struct sk_buff *skb, const struct xt_match_param *par) | |
185 | { | |
186 | return socket_match(skb, par, par->matchinfo); | |
187 | } | |
188 | ||
189 | static struct xt_match socket_mt_reg[] __read_mostly = { | |
190 | { | |
191 | .name = "socket", | |
192 | .revision = 0, | |
193 | .family = NFPROTO_IPV4, | |
194 | .match = socket_mt_v0, | |
aa3c487f JE |
195 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
196 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
197 | .me = THIS_MODULE, |
198 | }, | |
199 | { | |
200 | .name = "socket", | |
201 | .revision = 1, | |
202 | .family = NFPROTO_IPV4, | |
203 | .match = socket_mt_v1, | |
204 | .matchsize = sizeof(struct xt_socket_mtinfo1), | |
aa3c487f JE |
205 | .hooks = (1 << NF_INET_PRE_ROUTING) | |
206 | (1 << NF_INET_LOCAL_IN), | |
a31e1ffd LAT |
207 | .me = THIS_MODULE, |
208 | }, | |
136cdc71 KK |
209 | }; |
210 | ||
211 | static int __init socket_mt_init(void) | |
212 | { | |
213 | nf_defrag_ipv4_enable(); | |
a31e1ffd | 214 | return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
215 | } |
216 | ||
217 | static void __exit socket_mt_exit(void) | |
218 | { | |
a31e1ffd | 219 | xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
136cdc71 KK |
220 | } |
221 | ||
222 | module_init(socket_mt_init); | |
223 | module_exit(socket_mt_exit); | |
224 | ||
225 | MODULE_LICENSE("GPL"); | |
226 | MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler"); | |
227 | MODULE_DESCRIPTION("x_tables socket match module"); | |
228 | MODULE_ALIAS("ipt_socket"); |