netfilter: don't use INIT_RCU_HEAD()
[linux-2.6.git] / net / netfilter / xt_socket.c
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
25 #include <linux/netfilter/xt_socket.h>
26
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
91 socket_match(const struct sk_buff *skb, const struct xt_match_param *par,
92              const struct xt_socket_mtinfo1 *info)
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,
145                                    saddr, daddr, sport, dport, par->in, false);
146         if (sk != NULL) {
147                 bool wildcard;
148                 bool transparent = true;
149
150                 /* Ignore sockets listening on INADDR_ANY */
151                 wildcard = (sk->sk_state != TCP_TIME_WAIT &&
152                             inet_sk(sk)->inet_rcv_saddr == 0);
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));
161
162                 nf_tproxy_put_sock(sk);
163
164                 if (wildcard || !transparent)
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
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,
195                 .hooks          = (1 << NF_INET_PRE_ROUTING) |
196                                   (1 << NF_INET_LOCAL_IN),
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),
205                 .hooks          = (1 << NF_INET_PRE_ROUTING) |
206                                   (1 << NF_INET_LOCAL_IN),
207                 .me             = THIS_MODULE,
208         },
209 };
210
211 static int __init socket_mt_init(void)
212 {
213         nf_defrag_ipv4_enable();
214         return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
215 }
216
217 static void __exit socket_mt_exit(void)
218 {
219         xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
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");