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net: '&' redux
[linux-2.6/btrfs-unstable.git] / net / ipv4 / netfilter / nf_conntrack_l3proto_ipv4.c
blobb2141e11575ebb33cb93deec8202525a70348eb5
1
2 /* (C) 1999-2001 Paul `Rusty' Russell
3 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10 #include <linux/types.h>
11 #include <linux/ip.h>
12 #include <linux/netfilter.h>
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/icmp.h>
16 #include <linux/sysctl.h>
17 #include <net/route.h>
18 #include <net/ip.h>
19
20 #include <linux/netfilter_ipv4.h>
21 #include <net/netfilter/nf_conntrack.h>
22 #include <net/netfilter/nf_conntrack_helper.h>
23 #include <net/netfilter/nf_conntrack_l4proto.h>
24 #include <net/netfilter/nf_conntrack_l3proto.h>
25 #include <net/netfilter/nf_conntrack_core.h>
26 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
27 #include <net/netfilter/nf_nat_helper.h>
28 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
29
30 int (*nf_nat_seq_adjust_hook)(struct sk_buff *skb,
31 struct nf_conn *ct,
32 enum ip_conntrack_info ctinfo);
33 EXPORT_SYMBOL_GPL(nf_nat_seq_adjust_hook);
34
35 static bool ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
36 struct nf_conntrack_tuple *tuple)
37 {
38 const __be32 *ap;
39 __be32 _addrs[2];
40 ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
41 sizeof(u_int32_t) * 2, _addrs);
42 if (ap == NULL)
43 return false;
44
45 tuple->src.u3.ip = ap[0];
46 tuple->dst.u3.ip = ap[1];
47
48 return true;
49 }
50
51 static bool ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
52 const struct nf_conntrack_tuple *orig)
53 {
54 tuple->src.u3.ip = orig->dst.u3.ip;
55 tuple->dst.u3.ip = orig->src.u3.ip;
56
57 return true;
58 }
59
60 static int ipv4_print_tuple(struct seq_file *s,
61 const struct nf_conntrack_tuple *tuple)
62 {
63 return seq_printf(s, "src=%pI4 dst=%pI4 ",
64 &tuple->src.u3.ip, &tuple->dst.u3.ip);
65 }
66
67 static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
68 unsigned int *dataoff, u_int8_t *protonum)
69 {
70 const struct iphdr *iph;
71 struct iphdr _iph;
72
73 iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
74 if (iph == NULL)
75 return -NF_DROP;
76
77 /* Conntrack defragments packets, we might still see fragments
78 * inside ICMP packets though. */
79 if (iph->frag_off & htons(IP_OFFSET))
80 return -NF_DROP;
81
82 *dataoff = nhoff + (iph->ihl << 2);
83 *protonum = iph->protocol;
84
85 return NF_ACCEPT;
86 }
87
88 static unsigned int ipv4_confirm(unsigned int hooknum,
89 struct sk_buff *skb,
90 const struct net_device *in,
91 const struct net_device *out,
92 int (*okfn)(struct sk_buff *))
93 {
94 struct nf_conn *ct;
95 enum ip_conntrack_info ctinfo;
96 const struct nf_conn_help *help;
97 const struct nf_conntrack_helper *helper;
98 unsigned int ret;
99
100 /* This is where we call the helper: as the packet goes out. */
101 ct = nf_ct_get(skb, &ctinfo);
102 if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
103 goto out;
104
105 help = nfct_help(ct);
106 if (!help)
107 goto out;
108
109 /* rcu_read_lock()ed by nf_hook_slow */
110 helper = rcu_dereference(help->helper);
111 if (!helper)
112 goto out;
113
114 ret = helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
115 ct, ctinfo);
116 if (ret != NF_ACCEPT)
117 return ret;
118
119 if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) {
120 typeof(nf_nat_seq_adjust_hook) seq_adjust;
121
122 seq_adjust = rcu_dereference(nf_nat_seq_adjust_hook);
123 if (!seq_adjust || !seq_adjust(skb, ct, ctinfo))
124 return NF_DROP;
125 }
126 out:
127 /* We've seen it coming out the other side: confirm it */
128 return nf_conntrack_confirm(skb);
129 }
130
131 static unsigned int ipv4_conntrack_in(unsigned int hooknum,
132 struct sk_buff *skb,
133 const struct net_device *in,
134 const struct net_device *out,
135 int (*okfn)(struct sk_buff *))
136 {
137 return nf_conntrack_in(dev_net(in), PF_INET, hooknum, skb);
138 }
139
140 static unsigned int ipv4_conntrack_local(unsigned int hooknum,
141 struct sk_buff *skb,
142 const struct net_device *in,
143 const struct net_device *out,
144 int (*okfn)(struct sk_buff *))
145 {
146 /* root is playing with raw sockets. */
147 if (skb->len < sizeof(struct iphdr) ||
148 ip_hdrlen(skb) < sizeof(struct iphdr)) {
149 if (net_ratelimit())
150 printk("ipt_hook: happy cracking.\n");
151 return NF_ACCEPT;
152 }
153 return nf_conntrack_in(dev_net(out), PF_INET, hooknum, skb);
154 }
155
156 /* Connection tracking may drop packets, but never alters them, so
157 make it the first hook. */
158 static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = {
159 {
160 .hook = ipv4_conntrack_in,
161 .owner = THIS_MODULE,
162 .pf = PF_INET,
163 .hooknum = NF_INET_PRE_ROUTING,
164 .priority = NF_IP_PRI_CONNTRACK,
165 },
166 {
167 .hook = ipv4_conntrack_local,
168 .owner = THIS_MODULE,
169 .pf = PF_INET,
170 .hooknum = NF_INET_LOCAL_OUT,
171 .priority = NF_IP_PRI_CONNTRACK,
172 },
173 {
174 .hook = ipv4_confirm,
175 .owner = THIS_MODULE,
176 .pf = PF_INET,
177 .hooknum = NF_INET_POST_ROUTING,
178 .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
179 },
180 {
181 .hook = ipv4_confirm,
182 .owner = THIS_MODULE,
183 .pf = PF_INET,
184 .hooknum = NF_INET_LOCAL_IN,
185 .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
186 },
187 };
188
189 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
190 static int log_invalid_proto_min = 0;
191 static int log_invalid_proto_max = 255;
192
193 static ctl_table ip_ct_sysctl_table[] = {
194 {
195 .ctl_name = NET_IPV4_NF_CONNTRACK_MAX,
196 .procname = "ip_conntrack_max",
197 .data = &nf_conntrack_max,
198 .maxlen = sizeof(int),
199 .mode = 0644,
200 .proc_handler = proc_dointvec,
201 },
202 {
203 .ctl_name = NET_IPV4_NF_CONNTRACK_COUNT,
204 .procname = "ip_conntrack_count",
205 .data = &init_net.ct.count,
206 .maxlen = sizeof(int),
207 .mode = 0444,
208 .proc_handler = proc_dointvec,
209 },
210 {
211 .ctl_name = NET_IPV4_NF_CONNTRACK_BUCKETS,
212 .procname = "ip_conntrack_buckets",
213 .data = &nf_conntrack_htable_size,
214 .maxlen = sizeof(unsigned int),
215 .mode = 0444,
216 .proc_handler = proc_dointvec,
217 },
218 {
219 .ctl_name = NET_IPV4_NF_CONNTRACK_CHECKSUM,
220 .procname = "ip_conntrack_checksum",
221 .data = &init_net.ct.sysctl_checksum,
222 .maxlen = sizeof(int),
223 .mode = 0644,
224 .proc_handler = proc_dointvec,
225 },
226 {
227 .ctl_name = NET_IPV4_NF_CONNTRACK_LOG_INVALID,
228 .procname = "ip_conntrack_log_invalid",
229 .data = &init_net.ct.sysctl_log_invalid,
230 .maxlen = sizeof(unsigned int),
231 .mode = 0644,
232 .proc_handler = proc_dointvec_minmax,
233 .strategy = sysctl_intvec,
234 .extra1 = &log_invalid_proto_min,
235 .extra2 = &log_invalid_proto_max,
236 },
237 {
238 .ctl_name = 0
239 }
240 };
241 #endif /* CONFIG_SYSCTL && CONFIG_NF_CONNTRACK_PROC_COMPAT */
242
243 /* Fast function for those who don't want to parse /proc (and I don't
244 blame them). */
245 /* Reversing the socket's dst/src point of view gives us the reply
246 mapping. */
247 static int
248 getorigdst(struct sock *sk, int optval, void __user *user, int *len)
249 {
250 const struct inet_sock *inet = inet_sk(sk);
251 const struct nf_conntrack_tuple_hash *h;
252 struct nf_conntrack_tuple tuple;
253
254 memset(&tuple, 0, sizeof(tuple));
255 tuple.src.u3.ip = inet->rcv_saddr;
256 tuple.src.u.tcp.port = inet->sport;
257 tuple.dst.u3.ip = inet->daddr;
258 tuple.dst.u.tcp.port = inet->dport;
259 tuple.src.l3num = PF_INET;
260 tuple.dst.protonum = IPPROTO_TCP;
261
262 /* We only do TCP at the moment: is there a better way? */
263 if (strcmp(sk->sk_prot->name, "TCP")) {
264 pr_debug("SO_ORIGINAL_DST: Not a TCP socket\n");
265 return -ENOPROTOOPT;
266 }
267
268 if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
269 pr_debug("SO_ORIGINAL_DST: len %d not %Zu\n",
270 *len, sizeof(struct sockaddr_in));
271 return -EINVAL;
272 }
273
274 h = nf_conntrack_find_get(sock_net(sk), &tuple);
275 if (h) {
276 struct sockaddr_in sin;
277 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
278
279 sin.sin_family = AF_INET;
280 sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
281 .tuple.dst.u.tcp.port;
282 sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
283 .tuple.dst.u3.ip;
284 memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
285
286 pr_debug("SO_ORIGINAL_DST: %pI4 %u\n",
287 &sin.sin_addr.s_addr, ntohs(sin.sin_port));
288 nf_ct_put(ct);
289 if (copy_to_user(user, &sin, sizeof(sin)) != 0)
290 return -EFAULT;
291 else
292 return 0;
293 }
294 pr_debug("SO_ORIGINAL_DST: Can't find %pI4/%u-%pI4/%u.\n",
295 &tuple.src.u3.ip, ntohs(tuple.src.u.tcp.port),
296 &tuple.dst.u3.ip, ntohs(tuple.dst.u.tcp.port));
297 return -ENOENT;
298 }
299
300 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
301
302 #include <linux/netfilter/nfnetlink.h>
303 #include <linux/netfilter/nfnetlink_conntrack.h>
304
305 static int ipv4_tuple_to_nlattr(struct sk_buff *skb,
306 const struct nf_conntrack_tuple *tuple)
307 {
308 NLA_PUT_BE32(skb, CTA_IP_V4_SRC, tuple->src.u3.ip);
309 NLA_PUT_BE32(skb, CTA_IP_V4_DST, tuple->dst.u3.ip);
310 return 0;
311
312 nla_put_failure:
313 return -1;
314 }
315
316 static const struct nla_policy ipv4_nla_policy[CTA_IP_MAX+1] = {
317 [CTA_IP_V4_SRC] = { .type = NLA_U32 },
318 [CTA_IP_V4_DST] = { .type = NLA_U32 },
319 };
320
321 static int ipv4_nlattr_to_tuple(struct nlattr *tb[],
322 struct nf_conntrack_tuple *t)
323 {
324 if (!tb[CTA_IP_V4_SRC] || !tb[CTA_IP_V4_DST])
325 return -EINVAL;
326
327 t->src.u3.ip = nla_get_be32(tb[CTA_IP_V4_SRC]);
328 t->dst.u3.ip = nla_get_be32(tb[CTA_IP_V4_DST]);
329
330 return 0;
331 }
332 #endif
333
334 static struct nf_sockopt_ops so_getorigdst = {
335 .pf = PF_INET,
336 .get_optmin = SO_ORIGINAL_DST,
337 .get_optmax = SO_ORIGINAL_DST+1,
338 .get = &getorigdst,
339 .owner = THIS_MODULE,
340 };
341
342 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
343 .l3proto = PF_INET,
344 .name = "ipv4",
345 .pkt_to_tuple = ipv4_pkt_to_tuple,
346 .invert_tuple = ipv4_invert_tuple,
347 .print_tuple = ipv4_print_tuple,
348 .get_l4proto = ipv4_get_l4proto,
349 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
350 .tuple_to_nlattr = ipv4_tuple_to_nlattr,
351 .nlattr_to_tuple = ipv4_nlattr_to_tuple,
352 .nla_policy = ipv4_nla_policy,
353 #endif
354 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
355 .ctl_table_path = nf_net_ipv4_netfilter_sysctl_path,
356 .ctl_table = ip_ct_sysctl_table,
357 #endif
358 .me = THIS_MODULE,
359 };
360
361 module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
362 &nf_conntrack_htable_size, 0600);
363
364 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
365 MODULE_ALIAS("ip_conntrack");
366 MODULE_LICENSE("GPL");
367
368 static int __init nf_conntrack_l3proto_ipv4_init(void)
369 {
370 int ret = 0;
371
372 need_conntrack();
373 nf_defrag_ipv4_enable();
374
375 ret = nf_register_sockopt(&so_getorigdst);
376 if (ret < 0) {
377 printk(KERN_ERR "Unable to register netfilter socket option\n");
378 return ret;
379 }
380
381 ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp4);
382 if (ret < 0) {
383 printk("nf_conntrack_ipv4: can't register tcp.\n");
384 goto cleanup_sockopt;
385 }
386
387 ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp4);
388 if (ret < 0) {
389 printk("nf_conntrack_ipv4: can't register udp.\n");
390 goto cleanup_tcp;
391 }
392
393 ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmp);
394 if (ret < 0) {
395 printk("nf_conntrack_ipv4: can't register icmp.\n");
396 goto cleanup_udp;
397 }
398
399 ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv4);
400 if (ret < 0) {
401 printk("nf_conntrack_ipv4: can't register ipv4\n");
402 goto cleanup_icmp;
403 }
404
405 ret = nf_register_hooks(ipv4_conntrack_ops,
406 ARRAY_SIZE(ipv4_conntrack_ops));
407 if (ret < 0) {
408 printk("nf_conntrack_ipv4: can't register hooks.\n");
409 goto cleanup_ipv4;
410 }
411 #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
412 ret = nf_conntrack_ipv4_compat_init();
413 if (ret < 0)
414 goto cleanup_hooks;
415 #endif
416 return ret;
417 #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
418 cleanup_hooks:
419 nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
420 #endif
421 cleanup_ipv4:
422 nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
423 cleanup_icmp:
424 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
425 cleanup_udp:
426 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
427 cleanup_tcp:
428 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
429 cleanup_sockopt:
430 nf_unregister_sockopt(&so_getorigdst);
431 return ret;
432 }
433
434 static void __exit nf_conntrack_l3proto_ipv4_fini(void)
435 {
436 synchronize_net();
437 #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
438 nf_conntrack_ipv4_compat_fini();
439 #endif
440 nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
441 nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
442 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
443 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
444 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
445 nf_unregister_sockopt(&so_getorigdst);
446 }
447
448 module_init(nf_conntrack_l3proto_ipv4_init);
449 module_exit(nf_conntrack_l3proto_ipv4_fini);
450
451 void need_ipv4_conntrack(void)
452 {
453 return;
454 }
455 EXPORT_SYMBOL_GPL(need_ipv4_conntrack);
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