ipvs: ip_vs_sip_fill_param() BUG: bad check of return value
[linux-3.10.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 #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>
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 #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>
29 #endif
30
31 #include <linux/netfilter/xt_socket.h>
32
33 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
34 #define XT_SOCKET_HAVE_CONNTRACK 1
35 #include <net/netfilter/nf_conntrack.h>
36 #endif
37
38 static void
39 xt_socket_put_sk(struct sock *sk)
40 {
41         if (sk->sk_state == TCP_TIME_WAIT)
42                 inet_twsk_put(inet_twsk(sk));
43         else
44                 sock_put(sk);
45 }
46
47 static int
48 extract_icmp4_fields(const struct sk_buff *skb,
49                     u8 *protocol,
50                     __be32 *raddr,
51                     __be32 *laddr,
52                     __be16 *rport,
53                     __be16 *lport)
54 {
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];
59
60         icmph = skb_header_pointer(skb, outside_hdrlen,
61                                    sizeof(_icmph), &_icmph);
62         if (icmph == NULL)
63                 return 1;
64
65         switch (icmph->type) {
66         case ICMP_DEST_UNREACH:
67         case ICMP_SOURCE_QUENCH:
68         case ICMP_REDIRECT:
69         case ICMP_TIME_EXCEEDED:
70         case ICMP_PARAMETERPROB:
71                 break;
72         default:
73                 return 1;
74         }
75
76         inside_iph = skb_header_pointer(skb, outside_hdrlen +
77                                         sizeof(struct icmphdr),
78                                         sizeof(_inside_iph), &_inside_iph);
79         if (inside_iph == NULL)
80                 return 1;
81
82         if (inside_iph->protocol != IPPROTO_TCP &&
83             inside_iph->protocol != IPPROTO_UDP)
84                 return 1;
85
86         ports = skb_header_pointer(skb, outside_hdrlen +
87                                    sizeof(struct icmphdr) +
88                                    (inside_iph->ihl << 2),
89                                    sizeof(_ports), &_ports);
90         if (ports == NULL)
91                 return 1;
92
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;
97         *lport = ports[0];
98         *raddr = inside_iph->daddr;
99         *rport = ports[1];
100
101         return 0;
102 }
103
104 static bool
105 socket_match(const struct sk_buff *skb, struct xt_action_param *par,
106              const struct xt_socket_mtinfo1 *info)
107 {
108         const struct iphdr *iph = ip_hdr(skb);
109         struct udphdr _hdr, *hp = NULL;
110         struct sock *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;
117 #endif
118
119         if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
120                 hp = skb_header_pointer(skb, ip_hdrlen(skb),
121                                         sizeof(_hdr), &_hdr);
122                 if (hp == NULL)
123                         return false;
124
125                 protocol = iph->protocol;
126                 saddr = iph->saddr;
127                 sport = hp->source;
128                 daddr = iph->daddr;
129                 dport = hp->dest;
130
131         } else if (iph->protocol == IPPROTO_ICMP) {
132                 if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
133                                         &sport, &dport))
134                         return false;
135         } else {
136                 return false;
137         }
138
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. */
142
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)) {
150
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;
155         }
156 #endif
157
158         sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol,
159                                    saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY);
160         if (sk != NULL) {
161                 bool wildcard;
162                 bool transparent = true;
163
164                 /* Ignore sockets listening on INADDR_ANY */
165                 wildcard = (sk->sk_state != TCP_TIME_WAIT &&
166                             inet_sk(sk)->inet_rcv_saddr == 0);
167
168                 /* Ignore non-transparent sockets,
169                    if XT_SOCKET_TRANSPARENT is used */
170                 if (info && info->flags & XT_SOCKET_TRANSPARENT)
171                         transparent = ((sk->sk_state != TCP_TIME_WAIT &&
172                                         inet_sk(sk)->transparent) ||
173                                        (sk->sk_state == TCP_TIME_WAIT &&
174                                         inet_twsk(sk)->tw_transparent));
175
176                 xt_socket_put_sk(sk);
177
178                 if (wildcard || !transparent)
179                         sk = NULL;
180         }
181
182         pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",
183                  protocol, &saddr, ntohs(sport),
184                  &daddr, ntohs(dport),
185                  &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
186
187         return (sk != NULL);
188 }
189
190 static bool
191 socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par)
192 {
193         return socket_match(skb, par, NULL);
194 }
195
196 static bool
197 socket_mt4_v1(const struct sk_buff *skb, struct xt_action_param *par)
198 {
199         return socket_match(skb, par, par->matchinfo);
200 }
201
202 #ifdef XT_SOCKET_HAVE_IPV6
203
204 static int
205 extract_icmp6_fields(const struct sk_buff *skb,
206                      unsigned int outside_hdrlen,
207                      int *protocol,
208                      struct in6_addr **raddr,
209                      struct in6_addr **laddr,
210                      __be16 *rport,
211                      __be16 *lport)
212 {
213         struct ipv6hdr *inside_iph, _inside_iph;
214         struct icmp6hdr *icmph, _icmph;
215         __be16 *ports, _ports[2];
216         u8 inside_nexthdr;
217         __be16 inside_fragoff;
218         int inside_hdrlen;
219
220         icmph = skb_header_pointer(skb, outside_hdrlen,
221                                    sizeof(_icmph), &_icmph);
222         if (icmph == NULL)
223                 return 1;
224
225         if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK)
226                 return 1;
227
228         inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph);
229         if (inside_iph == NULL)
230                 return 1;
231         inside_nexthdr = inside_iph->nexthdr;
232
233         inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph),
234                                          &inside_nexthdr, &inside_fragoff);
235         if (inside_hdrlen < 0)
236                 return 1; /* hjm: Packet has no/incomplete transport layer headers. */
237
238         if (inside_nexthdr != IPPROTO_TCP &&
239             inside_nexthdr != IPPROTO_UDP)
240                 return 1;
241
242         ports = skb_header_pointer(skb, inside_hdrlen,
243                                    sizeof(_ports), &_ports);
244         if (ports == NULL)
245                 return 1;
246
247         /* the inside IP packet is the one quoted from our side, thus
248          * its saddr is the local address */
249         *protocol = inside_nexthdr;
250         *laddr = &inside_iph->saddr;
251         *lport = ports[0];
252         *raddr = &inside_iph->daddr;
253         *rport = ports[1];
254
255         return 0;
256 }
257
258 static bool
259 socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par)
260 {
261         struct ipv6hdr *iph = ipv6_hdr(skb);
262         struct udphdr _hdr, *hp = NULL;
263         struct sock *sk;
264         struct in6_addr *daddr = NULL, *saddr = NULL;
265         __be16 uninitialized_var(dport), uninitialized_var(sport);
266         int thoff = 0, uninitialized_var(tproto);
267         const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
268
269         tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
270         if (tproto < 0) {
271                 pr_debug("unable to find transport header in IPv6 packet, dropping\n");
272                 return NF_DROP;
273         }
274
275         if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {
276                 hp = skb_header_pointer(skb, thoff,
277                                         sizeof(_hdr), &_hdr);
278                 if (hp == NULL)
279                         return false;
280
281                 saddr = &iph->saddr;
282                 sport = hp->source;
283                 daddr = &iph->daddr;
284                 dport = hp->dest;
285
286         } else if (tproto == IPPROTO_ICMPV6) {
287                 if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
288                                          &sport, &dport))
289                         return false;
290         } else {
291                 return false;
292         }
293
294         sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
295                                    saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY);
296         if (sk != NULL) {
297                 bool wildcard;
298                 bool transparent = true;
299
300                 /* Ignore sockets listening on INADDR_ANY */
301                 wildcard = (sk->sk_state != TCP_TIME_WAIT &&
302                             ipv6_addr_any(&inet6_sk(sk)->rcv_saddr));
303
304                 /* Ignore non-transparent sockets,
305                    if XT_SOCKET_TRANSPARENT is used */
306                 if (info && info->flags & XT_SOCKET_TRANSPARENT)
307                         transparent = ((sk->sk_state != TCP_TIME_WAIT &&
308                                         inet_sk(sk)->transparent) ||
309                                        (sk->sk_state == TCP_TIME_WAIT &&
310                                         inet_twsk(sk)->tw_transparent));
311
312                 xt_socket_put_sk(sk);
313
314                 if (wildcard || !transparent)
315                         sk = NULL;
316         }
317
318         pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "
319                  "(orig %pI6:%hu) sock %p\n",
320                  tproto, saddr, ntohs(sport),
321                  daddr, ntohs(dport),
322                  &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
323
324         return (sk != NULL);
325 }
326 #endif
327
328 static struct xt_match socket_mt_reg[] __read_mostly = {
329         {
330                 .name           = "socket",
331                 .revision       = 0,
332                 .family         = NFPROTO_IPV4,
333                 .match          = socket_mt4_v0,
334                 .hooks          = (1 << NF_INET_PRE_ROUTING) |
335                                   (1 << NF_INET_LOCAL_IN),
336                 .me             = THIS_MODULE,
337         },
338         {
339                 .name           = "socket",
340                 .revision       = 1,
341                 .family         = NFPROTO_IPV4,
342                 .match          = socket_mt4_v1,
343                 .matchsize      = sizeof(struct xt_socket_mtinfo1),
344                 .hooks          = (1 << NF_INET_PRE_ROUTING) |
345                                   (1 << NF_INET_LOCAL_IN),
346                 .me             = THIS_MODULE,
347         },
348 #ifdef XT_SOCKET_HAVE_IPV6
349         {
350                 .name           = "socket",
351                 .revision       = 1,
352                 .family         = NFPROTO_IPV6,
353                 .match          = socket_mt6_v1,
354                 .matchsize      = sizeof(struct xt_socket_mtinfo1),
355                 .hooks          = (1 << NF_INET_PRE_ROUTING) |
356                                   (1 << NF_INET_LOCAL_IN),
357                 .me             = THIS_MODULE,
358         },
359 #endif
360 };
361
362 static int __init socket_mt_init(void)
363 {
364         nf_defrag_ipv4_enable();
365 #ifdef XT_SOCKET_HAVE_IPV6
366         nf_defrag_ipv6_enable();
367 #endif
368
369         return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
370 }
371
372 static void __exit socket_mt_exit(void)
373 {
374         xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
375 }
376
377 module_init(socket_mt_init);
378 module_exit(socket_mt_exit);
379
380 MODULE_LICENSE("GPL");
381 MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
382 MODULE_DESCRIPTION("x_tables socket match module");
383 MODULE_ALIAS("ipt_socket");
384 MODULE_ALIAS("ip6t_socket");