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_zones.h>
26 #include <net/netfilter/nf_conntrack_core.h>
27 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
28 #include <net/netfilter/nf_nat_helper.h>
29 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
30 #include <net/netfilter/nf_log.h>
31
32 int (*nf_nat_seq_adjust_hook)(struct sk_buff *skb,
33 struct nf_conn *ct,
34 enum ip_conntrack_info ctinfo);
35 EXPORT_SYMBOL_GPL(nf_nat_seq_adjust_hook);
36
ipv4_pkt_to_tuple(const struct sk_buff * skb,unsigned int nhoff,struct nf_conntrack_tuple * tuple)37 static bool ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
38 struct nf_conntrack_tuple *tuple)
39 {
40 const __be32 *ap;
41 __be32 _addrs[2];
42 ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
43 sizeof(u_int32_t) * 2, _addrs);
44 if (ap == NULL)
45 return false;
46
47 tuple->src.u3.ip = ap[0];
48 tuple->dst.u3.ip = ap[1];
49
50 return true;
51 }
52
ipv4_invert_tuple(struct nf_conntrack_tuple * tuple,const struct nf_conntrack_tuple * orig)53 static bool ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
54 const struct nf_conntrack_tuple *orig)
55 {
56 tuple->src.u3.ip = orig->dst.u3.ip;
57 tuple->dst.u3.ip = orig->src.u3.ip;
58
59 return true;
60 }
61
ipv4_print_tuple(struct seq_file * s,const struct nf_conntrack_tuple * tuple)62 static int ipv4_print_tuple(struct seq_file *s,
63 const struct nf_conntrack_tuple *tuple)
64 {
65 return seq_printf(s, "src=%pI4 dst=%pI4 ",
66 &tuple->src.u3.ip, &tuple->dst.u3.ip);
67 }
68
ipv4_get_l4proto(const struct sk_buff * skb,unsigned int nhoff,unsigned int * dataoff,u_int8_t * protonum)69 static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
70 unsigned int *dataoff, u_int8_t *protonum)
71 {
72 const struct iphdr *iph;
73 struct iphdr _iph;
74
75 iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
76 if (iph == NULL)
77 return -NF_DROP;
78
79 /* Conntrack defragments packets, we might still see fragments
80 * inside ICMP packets though. */
81 if (iph->frag_off & htons(IP_OFFSET))
82 return -NF_DROP;
83
84 *dataoff = nhoff + (iph->ihl << 2);
85 *protonum = iph->protocol;
86
87 return NF_ACCEPT;
88 }
89
ipv4_confirm(unsigned int hooknum,struct sk_buff * skb,const struct net_device * in,const struct net_device * out,int (* okfn)(struct sk_buff *))90 static unsigned int ipv4_confirm(unsigned int hooknum,
91 struct sk_buff *skb,
92 const struct net_device *in,
93 const struct net_device *out,
94 int (*okfn)(struct sk_buff *))
95 {
96 struct nf_conn *ct;
97 enum ip_conntrack_info ctinfo;
98 const struct nf_conn_help *help;
99 const struct nf_conntrack_helper *helper;
100 unsigned int ret;
101
102 /* This is where we call the helper: as the packet goes out. */
103 ct = nf_ct_get(skb, &ctinfo);
104 if (!ct || ctinfo == IP_CT_RELATED_REPLY)
105 goto out;
106
107 help = nfct_help(ct);
108 if (!help)
109 goto out;
110
111 /* rcu_read_lock()ed by nf_hook_slow */
112 helper = rcu_dereference(help->helper);
113 if (!helper)
114 goto out;
115
116 ret = helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
117 ct, ctinfo);
118 if (ret != NF_ACCEPT) {
119 nf_log_packet(NFPROTO_IPV4, hooknum, skb, in, out, NULL,
120 "nf_ct_%s: dropping packet", helper->name);
121 return ret;
122 }
123
124 /* adjust seqs for loopback traffic only in outgoing direction */
125 if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
126 !nf_is_loopback_packet(skb)) {
127 typeof(nf_nat_seq_adjust_hook) seq_adjust;
128
129 seq_adjust = rcu_dereference(nf_nat_seq_adjust_hook);
130 if (!seq_adjust || !seq_adjust(skb, ct, ctinfo)) {
131 NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
132 return NF_DROP;
133 }
134 }
135 out:
136 /* We've seen it coming out the other side: confirm it */
137 return nf_conntrack_confirm(skb);
138 }
139
ipv4_conntrack_in(unsigned int hooknum,struct sk_buff * skb,const struct net_device * in,const struct net_device * out,int (* okfn)(struct sk_buff *))140 static unsigned int ipv4_conntrack_in(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 return nf_conntrack_in(dev_net(in), PF_INET, hooknum, skb);
147 }
148
ipv4_conntrack_local(unsigned int hooknum,struct sk_buff * skb,const struct net_device * in,const struct net_device * out,int (* okfn)(struct sk_buff *))149 static unsigned int ipv4_conntrack_local(unsigned int hooknum,
150 struct sk_buff *skb,
151 const struct net_device *in,
152 const struct net_device *out,
153 int (*okfn)(struct sk_buff *))
154 {
155 /* root is playing with raw sockets. */
156 if (skb->len < sizeof(struct iphdr) ||
157 ip_hdrlen(skb) < sizeof(struct iphdr))
158 return NF_ACCEPT;
159 return nf_conntrack_in(dev_net(out), PF_INET, hooknum, skb);
160 }
161
162 /* Connection tracking may drop packets, but never alters them, so
163 make it the first hook. */
164 static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = {
165 {
166 .hook = ipv4_conntrack_in,
167 .owner = THIS_MODULE,
168 .pf = NFPROTO_IPV4,
169 .hooknum = NF_INET_PRE_ROUTING,
170 .priority = NF_IP_PRI_CONNTRACK,
171 },
172 {
173 .hook = ipv4_conntrack_local,
174 .owner = THIS_MODULE,
175 .pf = NFPROTO_IPV4,
176 .hooknum = NF_INET_LOCAL_OUT,
177 .priority = NF_IP_PRI_CONNTRACK,
178 },
179 {
180 .hook = ipv4_confirm,
181 .owner = THIS_MODULE,
182 .pf = NFPROTO_IPV4,
183 .hooknum = NF_INET_POST_ROUTING,
184 .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
185 },
186 {
187 .hook = ipv4_confirm,
188 .owner = THIS_MODULE,
189 .pf = NFPROTO_IPV4,
190 .hooknum = NF_INET_LOCAL_IN,
191 .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
192 },
193 };
194
195 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
196 static int log_invalid_proto_min = 0;
197 static int log_invalid_proto_max = 255;
198
199 static ctl_table ip_ct_sysctl_table[] = {
200 {
201 .procname = "ip_conntrack_max",
202 .data = &nf_conntrack_max,
203 .maxlen = sizeof(int),
204 .mode = 0644,
205 .proc_handler = proc_dointvec,
206 },
207 {
208 .procname = "ip_conntrack_count",
209 .data = &init_net.ct.count,
210 .maxlen = sizeof(int),
211 .mode = 0444,
212 .proc_handler = proc_dointvec,
213 },
214 {
215 .procname = "ip_conntrack_buckets",
216 .data = &init_net.ct.htable_size,
217 .maxlen = sizeof(unsigned int),
218 .mode = 0444,
219 .proc_handler = proc_dointvec,
220 },
221 {
222 .procname = "ip_conntrack_checksum",
223 .data = &init_net.ct.sysctl_checksum,
224 .maxlen = sizeof(int),
225 .mode = 0644,
226 .proc_handler = proc_dointvec,
227 },
228 {
229 .procname = "ip_conntrack_log_invalid",
230 .data = &init_net.ct.sysctl_log_invalid,
231 .maxlen = sizeof(unsigned int),
232 .mode = 0644,
233 .proc_handler = proc_dointvec_minmax,
234 .extra1 = &log_invalid_proto_min,
235 .extra2 = &log_invalid_proto_max,
236 },
237 { }
238 };
239 #endif /* CONFIG_SYSCTL && CONFIG_NF_CONNTRACK_PROC_COMPAT */
240
241 /* Fast function for those who don't want to parse /proc (and I don't
242 blame them). */
243 /* Reversing the socket's dst/src point of view gives us the reply
244 mapping. */
245 static int
getorigdst(struct sock * sk,int optval,void __user * user,int * len)246 getorigdst(struct sock *sk, int optval, void __user *user, int *len)
247 {
248 const struct inet_sock *inet = inet_sk(sk);
249 const struct nf_conntrack_tuple_hash *h;
250 struct nf_conntrack_tuple tuple;
251
252 memset(&tuple, 0, sizeof(tuple));
253 tuple.src.u3.ip = inet->inet_rcv_saddr;
254 tuple.src.u.tcp.port = inet->inet_sport;
255 tuple.dst.u3.ip = inet->inet_daddr;
256 tuple.dst.u.tcp.port = inet->inet_dport;
257 tuple.src.l3num = PF_INET;
258 tuple.dst.protonum = sk->sk_protocol;
259
260 /* We only do TCP and SCTP at the moment: is there a better way? */
261 if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != IPPROTO_SCTP) {
262 pr_debug("SO_ORIGINAL_DST: Not a TCP/SCTP socket\n");
263 return -ENOPROTOOPT;
264 }
265
266 if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
267 pr_debug("SO_ORIGINAL_DST: len %d not %Zu\n",
268 *len, sizeof(struct sockaddr_in));
269 return -EINVAL;
270 }
271
272 h = nf_conntrack_find_get(sock_net(sk), NF_CT_DEFAULT_ZONE, &tuple);
273 if (h) {
274 struct sockaddr_in sin;
275 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
276
277 sin.sin_family = AF_INET;
278 sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
279 .tuple.dst.u.tcp.port;
280 sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
281 .tuple.dst.u3.ip;
282 memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
283
284 pr_debug("SO_ORIGINAL_DST: %pI4 %u\n",
285 &sin.sin_addr.s_addr, ntohs(sin.sin_port));
286 nf_ct_put(ct);
287 if (copy_to_user(user, &sin, sizeof(sin)) != 0)
288 return -EFAULT;
289 else
290 return 0;
291 }
292 pr_debug("SO_ORIGINAL_DST: Can't find %pI4/%u-%pI4/%u.\n",
293 &tuple.src.u3.ip, ntohs(tuple.src.u.tcp.port),
294 &tuple.dst.u3.ip, ntohs(tuple.dst.u.tcp.port));
295 return -ENOENT;
296 }
297
298 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
299
300 #include <linux/netfilter/nfnetlink.h>
301 #include <linux/netfilter/nfnetlink_conntrack.h>
302
ipv4_tuple_to_nlattr(struct sk_buff * skb,const struct nf_conntrack_tuple * tuple)303 static int ipv4_tuple_to_nlattr(struct sk_buff *skb,
304 const struct nf_conntrack_tuple *tuple)
305 {
306 NLA_PUT_BE32(skb, CTA_IP_V4_SRC, tuple->src.u3.ip);
307 NLA_PUT_BE32(skb, CTA_IP_V4_DST, tuple->dst.u3.ip);
308 return 0;
309
310 nla_put_failure:
311 return -1;
312 }
313
314 static const struct nla_policy ipv4_nla_policy[CTA_IP_MAX+1] = {
315 [CTA_IP_V4_SRC] = { .type = NLA_U32 },
316 [CTA_IP_V4_DST] = { .type = NLA_U32 },
317 };
318
ipv4_nlattr_to_tuple(struct nlattr * tb[],struct nf_conntrack_tuple * t)319 static int ipv4_nlattr_to_tuple(struct nlattr *tb[],
320 struct nf_conntrack_tuple *t)
321 {
322 if (!tb[CTA_IP_V4_SRC] || !tb[CTA_IP_V4_DST])
323 return -EINVAL;
324
325 t->src.u3.ip = nla_get_be32(tb[CTA_IP_V4_SRC]);
326 t->dst.u3.ip = nla_get_be32(tb[CTA_IP_V4_DST]);
327
328 return 0;
329 }
330
ipv4_nlattr_tuple_size(void)331 static int ipv4_nlattr_tuple_size(void)
332 {
333 return nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1);
334 }
335 #endif
336
337 static struct nf_sockopt_ops so_getorigdst = {
338 .pf = PF_INET,
339 .get_optmin = SO_ORIGINAL_DST,
340 .get_optmax = SO_ORIGINAL_DST+1,
341 .get = &getorigdst,
342 .owner = THIS_MODULE,
343 };
344
345 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
346 .l3proto = PF_INET,
347 .name = "ipv4",
348 .pkt_to_tuple = ipv4_pkt_to_tuple,
349 .invert_tuple = ipv4_invert_tuple,
350 .print_tuple = ipv4_print_tuple,
351 .get_l4proto = ipv4_get_l4proto,
352 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
353 .tuple_to_nlattr = ipv4_tuple_to_nlattr,
354 .nlattr_tuple_size = ipv4_nlattr_tuple_size,
355 .nlattr_to_tuple = ipv4_nlattr_to_tuple,
356 .nla_policy = ipv4_nla_policy,
357 #endif
358 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
359 .ctl_table_path = nf_net_ipv4_netfilter_sysctl_path,
360 .ctl_table = ip_ct_sysctl_table,
361 #endif
362 .me = THIS_MODULE,
363 };
364
365 module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
366 &nf_conntrack_htable_size, 0600);
367
368 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
369 MODULE_ALIAS("ip_conntrack");
370 MODULE_LICENSE("GPL");
371
nf_conntrack_l3proto_ipv4_init(void)372 static int __init nf_conntrack_l3proto_ipv4_init(void)
373 {
374 int ret = 0;
375
376 need_conntrack();
377 nf_defrag_ipv4_enable();
378
379 ret = nf_register_sockopt(&so_getorigdst);
380 if (ret < 0) {
381 printk(KERN_ERR "Unable to register netfilter socket option\n");
382 return ret;
383 }
384
385 ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp4);
386 if (ret < 0) {
387 pr_err("nf_conntrack_ipv4: can't register tcp.\n");
388 goto cleanup_sockopt;
389 }
390
391 ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp4);
392 if (ret < 0) {
393 pr_err("nf_conntrack_ipv4: can't register udp.\n");
394 goto cleanup_tcp;
395 }
396
397 ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmp);
398 if (ret < 0) {
399 pr_err("nf_conntrack_ipv4: can't register icmp.\n");
400 goto cleanup_udp;
401 }
402
403 ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv4);
404 if (ret < 0) {
405 pr_err("nf_conntrack_ipv4: can't register ipv4\n");
406 goto cleanup_icmp;
407 }
408
409 ret = nf_register_hooks(ipv4_conntrack_ops,
410 ARRAY_SIZE(ipv4_conntrack_ops));
411 if (ret < 0) {
412 pr_err("nf_conntrack_ipv4: can't register hooks.\n");
413 goto cleanup_ipv4;
414 }
415 #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
416 ret = nf_conntrack_ipv4_compat_init();
417 if (ret < 0)
418 goto cleanup_hooks;
419 #endif
420 return ret;
421 #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
422 cleanup_hooks:
423 nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
424 #endif
425 cleanup_ipv4:
426 nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
427 cleanup_icmp:
428 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
429 cleanup_udp:
430 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
431 cleanup_tcp:
432 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
433 cleanup_sockopt:
434 nf_unregister_sockopt(&so_getorigdst);
435 return ret;
436 }
437
nf_conntrack_l3proto_ipv4_fini(void)438 static void __exit nf_conntrack_l3proto_ipv4_fini(void)
439 {
440 synchronize_net();
441 #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
442 nf_conntrack_ipv4_compat_fini();
443 #endif
444 nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
445 nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
446 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
447 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
448 nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
449 nf_unregister_sockopt(&so_getorigdst);
450 }
451
452 module_init(nf_conntrack_l3proto_ipv4_init);
453 module_exit(nf_conntrack_l3proto_ipv4_fini);
454
need_ipv4_conntrack(void)455 void need_ipv4_conntrack(void)
456 {
457 return;
458 }
459 EXPORT_SYMBOL_GPL(need_ipv4_conntrack);
460