[NETFILTER]: nf_conntrack: move extern declaration to header files
[linux-2.6.git] / net / ipv4 / netfilter / nf_conntrack_l3proto_ipv4.c
1 /* (C) 1999-2001 Paul `Rusty' Russell
2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
9  *      - move L3 protocol dependent part to this file.
10  * 23 Mar 2004: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
11  *      - add get_features() to support various size of conntrack
12  *        structures.
13  *
14  * Derived from net/ipv4/netfilter/ip_conntrack_standalone.c
15  */
16
17 #include <linux/types.h>
18 #include <linux/ip.h>
19 #include <linux/netfilter.h>
20 #include <linux/module.h>
21 #include <linux/skbuff.h>
22 #include <linux/icmp.h>
23 #include <linux/sysctl.h>
24 #include <net/route.h>
25 #include <net/ip.h>
26
27 #include <linux/netfilter_ipv4.h>
28 #include <net/netfilter/nf_conntrack.h>
29 #include <net/netfilter/nf_conntrack_helper.h>
30 #include <net/netfilter/nf_conntrack_l4proto.h>
31 #include <net/netfilter/nf_conntrack_l3proto.h>
32 #include <net/netfilter/nf_conntrack_core.h>
33 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
34
35 #if 0
36 #define DEBUGP printk
37 #else
38 #define DEBUGP(format, args...)
39 #endif
40
41 static int ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
42                              struct nf_conntrack_tuple *tuple)
43 {
44         u_int32_t _addrs[2], *ap;
45         ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
46                                 sizeof(u_int32_t) * 2, _addrs);
47         if (ap == NULL)
48                 return 0;
49
50         tuple->src.u3.ip = ap[0];
51         tuple->dst.u3.ip = ap[1];
52
53         return 1;
54 }
55
56 static int ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
57                            const struct nf_conntrack_tuple *orig)
58 {
59         tuple->src.u3.ip = orig->dst.u3.ip;
60         tuple->dst.u3.ip = orig->src.u3.ip;
61
62         return 1;
63 }
64
65 static int ipv4_print_tuple(struct seq_file *s,
66                             const struct nf_conntrack_tuple *tuple)
67 {
68         return seq_printf(s, "src=%u.%u.%u.%u dst=%u.%u.%u.%u ",
69                           NIPQUAD(tuple->src.u3.ip),
70                           NIPQUAD(tuple->dst.u3.ip));
71 }
72
73 static int ipv4_print_conntrack(struct seq_file *s,
74                                 const struct nf_conn *conntrack)
75 {
76         return 0;
77 }
78
79 /* Returns new sk_buff, or NULL */
80 static struct sk_buff *
81 nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
82 {
83         skb_orphan(skb);
84
85         local_bh_disable();
86         skb = ip_defrag(skb, user);
87         local_bh_enable();
88
89         if (skb)
90                 ip_send_check(skb->nh.iph);
91
92         return skb;
93 }
94
95 static int
96 ipv4_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
97              u_int8_t *protonum)
98 {
99         /* Never happen */
100         if ((*pskb)->nh.iph->frag_off & htons(IP_OFFSET)) {
101                 if (net_ratelimit()) {
102                         printk(KERN_ERR "ipv4_prepare: Frag of proto %u (hook=%u)\n",
103                         (*pskb)->nh.iph->protocol, hooknum);
104                 }
105                 return -NF_DROP;
106         }
107
108         *dataoff = (*pskb)->nh.raw - (*pskb)->data + (*pskb)->nh.iph->ihl*4;
109         *protonum = (*pskb)->nh.iph->protocol;
110
111         return NF_ACCEPT;
112 }
113
114 int nat_module_is_loaded = 0;
115 static u_int32_t ipv4_get_features(const struct nf_conntrack_tuple *tuple)
116 {
117         if (nat_module_is_loaded)
118                 return NF_CT_F_NAT;
119
120         return NF_CT_F_BASIC;
121 }
122
123 static unsigned int ipv4_confirm(unsigned int hooknum,
124                                  struct sk_buff **pskb,
125                                  const struct net_device *in,
126                                  const struct net_device *out,
127                                  int (*okfn)(struct sk_buff *))
128 {
129         /* We've seen it coming out the other side: confirm it */
130         return nf_conntrack_confirm(pskb);
131 }
132
133 static unsigned int ipv4_conntrack_help(unsigned int hooknum,
134                                       struct sk_buff **pskb,
135                                       const struct net_device *in,
136                                       const struct net_device *out,
137                                       int (*okfn)(struct sk_buff *))
138 {
139         struct nf_conn *ct;
140         enum ip_conntrack_info ctinfo;
141         struct nf_conn_help *help;
142
143         /* This is where we call the helper: as the packet goes out. */
144         ct = nf_ct_get(*pskb, &ctinfo);
145         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
146                 return NF_ACCEPT;
147
148         help = nfct_help(ct);
149         if (!help || !help->helper)
150                 return NF_ACCEPT;
151
152         return help->helper->help(pskb,
153                                (*pskb)->nh.raw - (*pskb)->data
154                                                + (*pskb)->nh.iph->ihl*4,
155                                ct, ctinfo);
156 }
157
158 static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
159                                           struct sk_buff **pskb,
160                                           const struct net_device *in,
161                                           const struct net_device *out,
162                                           int (*okfn)(struct sk_buff *))
163 {
164 #if !defined(CONFIG_IP_NF_NAT) && !defined(CONFIG_IP_NF_NAT_MODULE)
165         /* Previously seen (loopback)?  Ignore.  Do this before
166            fragment check. */
167         if ((*pskb)->nfct)
168                 return NF_ACCEPT;
169 #endif
170
171         /* Gather fragments. */
172         if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
173                 *pskb = nf_ct_ipv4_gather_frags(*pskb,
174                                                 hooknum == NF_IP_PRE_ROUTING ?
175                                                 IP_DEFRAG_CONNTRACK_IN :
176                                                 IP_DEFRAG_CONNTRACK_OUT);
177                 if (!*pskb)
178                         return NF_STOLEN;
179         }
180         return NF_ACCEPT;
181 }
182
183 static unsigned int ipv4_conntrack_in(unsigned int hooknum,
184                                       struct sk_buff **pskb,
185                                       const struct net_device *in,
186                                       const struct net_device *out,
187                                       int (*okfn)(struct sk_buff *))
188 {
189         return nf_conntrack_in(PF_INET, hooknum, pskb);
190 }
191
192 static unsigned int ipv4_conntrack_local(unsigned int hooknum,
193                                          struct sk_buff **pskb,
194                                          const struct net_device *in,
195                                          const struct net_device *out,
196                                          int (*okfn)(struct sk_buff *))
197 {
198         /* root is playing with raw sockets. */
199         if ((*pskb)->len < sizeof(struct iphdr)
200             || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {
201                 if (net_ratelimit())
202                         printk("ipt_hook: happy cracking.\n");
203                 return NF_ACCEPT;
204         }
205         return nf_conntrack_in(PF_INET, hooknum, pskb);
206 }
207
208 /* Connection tracking may drop packets, but never alters them, so
209    make it the first hook. */
210 static struct nf_hook_ops ipv4_conntrack_ops[] = {
211         {
212                 .hook           = ipv4_conntrack_defrag,
213                 .owner          = THIS_MODULE,
214                 .pf             = PF_INET,
215                 .hooknum        = NF_IP_PRE_ROUTING,
216                 .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
217         },
218         {
219                 .hook           = ipv4_conntrack_in,
220                 .owner          = THIS_MODULE,
221                 .pf             = PF_INET,
222                 .hooknum        = NF_IP_PRE_ROUTING,
223                 .priority       = NF_IP_PRI_CONNTRACK,
224         },
225         {
226                 .hook           = ipv4_conntrack_defrag,
227                 .owner          = THIS_MODULE,
228                 .pf             = PF_INET,
229                 .hooknum        = NF_IP_LOCAL_OUT,
230                 .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
231         },
232         {
233                 .hook           = ipv4_conntrack_local,
234                 .owner          = THIS_MODULE,
235                 .pf             = PF_INET,
236                 .hooknum        = NF_IP_LOCAL_OUT,
237                 .priority       = NF_IP_PRI_CONNTRACK,
238         },
239         {
240                 .hook           = ipv4_conntrack_help,
241                 .owner          = THIS_MODULE,
242                 .pf             = PF_INET,
243                 .hooknum        = NF_IP_POST_ROUTING,
244                 .priority       = NF_IP_PRI_CONNTRACK_HELPER,
245         },
246         {
247                 .hook           = ipv4_conntrack_help,
248                 .owner          = THIS_MODULE,
249                 .pf             = PF_INET,
250                 .hooknum        = NF_IP_LOCAL_IN,
251                 .priority       = NF_IP_PRI_CONNTRACK_HELPER,
252         },
253         {
254                 .hook           = ipv4_confirm,
255                 .owner          = THIS_MODULE,
256                 .pf             = PF_INET,
257                 .hooknum        = NF_IP_POST_ROUTING,
258                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM,
259         },
260         {
261                 .hook           = ipv4_confirm,
262                 .owner          = THIS_MODULE,
263                 .pf             = PF_INET,
264                 .hooknum        = NF_IP_LOCAL_IN,
265                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM,
266         },
267 };
268
269 #ifdef CONFIG_SYSCTL
270 /* From nf_conntrack_proto_icmp.c */
271 extern unsigned int nf_ct_icmp_timeout;
272 static struct ctl_table_header *nf_ct_ipv4_sysctl_header;
273
274 static ctl_table nf_ct_sysctl_table[] = {
275         {
276                 .ctl_name       = NET_NF_CONNTRACK_ICMP_TIMEOUT,
277                 .procname       = "nf_conntrack_icmp_timeout",
278                 .data           = &nf_ct_icmp_timeout,
279                 .maxlen         = sizeof(unsigned int),
280                 .mode           = 0644,
281                 .proc_handler   = &proc_dointvec_jiffies,
282         },
283         { .ctl_name = 0 }
284 };
285
286 static ctl_table nf_ct_netfilter_table[] = {
287         {
288                 .ctl_name       = NET_NETFILTER,
289                 .procname       = "netfilter",
290                 .mode           = 0555,
291                 .child          = nf_ct_sysctl_table,
292         },
293         { .ctl_name = 0 }
294 };
295
296 static ctl_table nf_ct_net_table[] = {
297         {
298                 .ctl_name       = CTL_NET,
299                 .procname       = "net",
300                 .mode           = 0555,
301                 .child          = nf_ct_netfilter_table,
302         },
303         { .ctl_name = 0 }
304 };
305 #endif
306
307 /* Fast function for those who don't want to parse /proc (and I don't
308    blame them). */
309 /* Reversing the socket's dst/src point of view gives us the reply
310    mapping. */
311 static int
312 getorigdst(struct sock *sk, int optval, void __user *user, int *len)
313 {
314         struct inet_sock *inet = inet_sk(sk);
315         struct nf_conntrack_tuple_hash *h;
316         struct nf_conntrack_tuple tuple;
317         
318         NF_CT_TUPLE_U_BLANK(&tuple);
319         tuple.src.u3.ip = inet->rcv_saddr;
320         tuple.src.u.tcp.port = inet->sport;
321         tuple.dst.u3.ip = inet->daddr;
322         tuple.dst.u.tcp.port = inet->dport;
323         tuple.src.l3num = PF_INET;
324         tuple.dst.protonum = IPPROTO_TCP;
325
326         /* We only do TCP at the moment: is there a better way? */
327         if (strcmp(sk->sk_prot->name, "TCP")) {
328                 DEBUGP("SO_ORIGINAL_DST: Not a TCP socket\n");
329                 return -ENOPROTOOPT;
330         }
331
332         if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
333                 DEBUGP("SO_ORIGINAL_DST: len %u not %u\n",
334                        *len, sizeof(struct sockaddr_in));
335                 return -EINVAL;
336         }
337
338         h = nf_conntrack_find_get(&tuple, NULL);
339         if (h) {
340                 struct sockaddr_in sin;
341                 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
342
343                 sin.sin_family = AF_INET;
344                 sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
345                         .tuple.dst.u.tcp.port;
346                 sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
347                         .tuple.dst.u3.ip;
348                 memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
349
350                 DEBUGP("SO_ORIGINAL_DST: %u.%u.%u.%u %u\n",
351                        NIPQUAD(sin.sin_addr.s_addr), ntohs(sin.sin_port));
352                 nf_ct_put(ct);
353                 if (copy_to_user(user, &sin, sizeof(sin)) != 0)
354                         return -EFAULT;
355                 else
356                         return 0;
357         }
358         DEBUGP("SO_ORIGINAL_DST: Can't find %u.%u.%u.%u/%u-%u.%u.%u.%u/%u.\n",
359                NIPQUAD(tuple.src.u3.ip), ntohs(tuple.src.u.tcp.port),
360                NIPQUAD(tuple.dst.u3.ip), ntohs(tuple.dst.u.tcp.port));
361         return -ENOENT;
362 }
363
364 #if defined(CONFIG_NF_CT_NETLINK) || \
365     defined(CONFIG_NF_CT_NETLINK_MODULE)
366
367 #include <linux/netfilter/nfnetlink.h>
368 #include <linux/netfilter/nfnetlink_conntrack.h>
369
370 static int ipv4_tuple_to_nfattr(struct sk_buff *skb,
371                                 const struct nf_conntrack_tuple *tuple)
372 {
373         NFA_PUT(skb, CTA_IP_V4_SRC, sizeof(u_int32_t),
374                 &tuple->src.u3.ip);
375         NFA_PUT(skb, CTA_IP_V4_DST, sizeof(u_int32_t),
376                 &tuple->dst.u3.ip);
377         return 0;
378
379 nfattr_failure:
380         return -1;
381 }
382
383 static const size_t cta_min_ip[CTA_IP_MAX] = {
384         [CTA_IP_V4_SRC-1]       = sizeof(u_int32_t),
385         [CTA_IP_V4_DST-1]       = sizeof(u_int32_t),
386 };
387
388 static int ipv4_nfattr_to_tuple(struct nfattr *tb[],
389                                 struct nf_conntrack_tuple *t)
390 {
391         if (!tb[CTA_IP_V4_SRC-1] || !tb[CTA_IP_V4_DST-1])
392                 return -EINVAL;
393
394         if (nfattr_bad_size(tb, CTA_IP_MAX, cta_min_ip))
395                 return -EINVAL;
396
397         t->src.u3.ip =
398                 *(u_int32_t *)NFA_DATA(tb[CTA_IP_V4_SRC-1]);
399         t->dst.u3.ip =
400                 *(u_int32_t *)NFA_DATA(tb[CTA_IP_V4_DST-1]);
401
402         return 0;
403 }
404 #endif
405
406 static struct nf_sockopt_ops so_getorigdst = {
407         .pf             = PF_INET,
408         .get_optmin     = SO_ORIGINAL_DST,
409         .get_optmax     = SO_ORIGINAL_DST+1,
410         .get            = &getorigdst,
411 };
412
413 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 = {
414         .l3proto         = PF_INET,
415         .name            = "ipv4",
416         .pkt_to_tuple    = ipv4_pkt_to_tuple,
417         .invert_tuple    = ipv4_invert_tuple,
418         .print_tuple     = ipv4_print_tuple,
419         .print_conntrack = ipv4_print_conntrack,
420         .prepare         = ipv4_prepare,
421         .get_features    = ipv4_get_features,
422 #if defined(CONFIG_NF_CT_NETLINK) || \
423     defined(CONFIG_NF_CT_NETLINK_MODULE)
424         .tuple_to_nfattr = ipv4_tuple_to_nfattr,
425         .nfattr_to_tuple = ipv4_nfattr_to_tuple,
426 #endif
427         .me              = THIS_MODULE,
428 };
429
430 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
431 MODULE_LICENSE("GPL");
432
433 static int __init nf_conntrack_l3proto_ipv4_init(void)
434 {
435         int ret = 0;
436
437         need_conntrack();
438
439         ret = nf_register_sockopt(&so_getorigdst);
440         if (ret < 0) {
441                 printk(KERN_ERR "Unable to register netfilter socket option\n");
442                 return ret;
443         }
444
445         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp4);
446         if (ret < 0) {
447                 printk("nf_conntrack_ipv4: can't register tcp.\n");
448                 goto cleanup_sockopt;
449         }
450
451         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp4);
452         if (ret < 0) {
453                 printk("nf_conntrack_ipv4: can't register udp.\n");
454                 goto cleanup_tcp;
455         }
456
457         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmp);
458         if (ret < 0) {
459                 printk("nf_conntrack_ipv4: can't register icmp.\n");
460                 goto cleanup_udp;
461         }
462
463         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv4);
464         if (ret < 0) {
465                 printk("nf_conntrack_ipv4: can't register ipv4\n");
466                 goto cleanup_icmp;
467         }
468
469         ret = nf_register_hooks(ipv4_conntrack_ops,
470                                 ARRAY_SIZE(ipv4_conntrack_ops));
471         if (ret < 0) {
472                 printk("nf_conntrack_ipv4: can't register hooks.\n");
473                 goto cleanup_ipv4;
474         }
475 #ifdef CONFIG_SYSCTL
476         nf_ct_ipv4_sysctl_header = register_sysctl_table(nf_ct_net_table, 0);
477         if (nf_ct_ipv4_sysctl_header == NULL) {
478                 printk("nf_conntrack: can't register to sysctl.\n");
479                 ret = -ENOMEM;
480                 goto cleanup_hooks;
481         }
482 #endif
483         return ret;
484
485 #ifdef CONFIG_SYSCTL
486  cleanup_hooks:
487         nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
488 #endif
489  cleanup_ipv4:
490         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
491  cleanup_icmp:
492         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
493  cleanup_udp:
494         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
495  cleanup_tcp:
496         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
497  cleanup_sockopt:
498         nf_unregister_sockopt(&so_getorigdst);
499         return ret;
500 }
501
502 static void __exit nf_conntrack_l3proto_ipv4_fini(void)
503 {
504         synchronize_net();
505 #ifdef CONFIG_SYSCTL
506         unregister_sysctl_table(nf_ct_ipv4_sysctl_header);
507 #endif
508         nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
509         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
510         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
511         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
512         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
513         nf_unregister_sockopt(&so_getorigdst);
514 }
515
516 module_init(nf_conntrack_l3proto_ipv4_init);
517 module_exit(nf_conntrack_l3proto_ipv4_fini);
518
519 EXPORT_SYMBOL(nf_ct_ipv4_gather_frags);