2 /* (C) 1999-2001 Paul `Rusty' Russell
3 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
4 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 #include <linux/types.h>
13 #include <linux/netfilter.h>
14 #include <linux/module.h>
15 #include <linux/skbuff.h>
16 #include <linux/icmp.h>
17 #include <linux/sysctl.h>
18 #include <net/route.h>
21 #include <linux/netfilter_ipv4.h>
22 #include <net/netfilter/nf_conntrack.h>
23 #include <net/netfilter/nf_conntrack_helper.h>
24 #include <net/netfilter/nf_conntrack_l4proto.h>
25 #include <net/netfilter/nf_conntrack_l3proto.h>
26 #include <net/netfilter/nf_conntrack_zones.h>
27 #include <net/netfilter/nf_conntrack_core.h>
28 #include <net/netfilter/nf_conntrack_seqadj.h>
29 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
30 #include <net/netfilter/nf_nat_helper.h>
31 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
32 #include <net/netfilter/nf_log.h>
34 static int conntrack4_net_id __read_mostly;
35 static DEFINE_MUTEX(register_ipv4_hooks);
37 struct conntrack4_net {
41 static bool ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
42 struct nf_conntrack_tuple *tuple)
46 ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
47 sizeof(u_int32_t) * 2, _addrs);
51 tuple->src.u3.ip = ap[0];
52 tuple->dst.u3.ip = ap[1];
57 static bool ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
58 const struct nf_conntrack_tuple *orig)
60 tuple->src.u3.ip = orig->dst.u3.ip;
61 tuple->dst.u3.ip = orig->src.u3.ip;
66 static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
67 unsigned int *dataoff, u_int8_t *protonum)
69 const struct iphdr *iph;
72 iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
76 /* Conntrack defragments packets, we might still see fragments
77 * inside ICMP packets though. */
78 if (iph->frag_off & htons(IP_OFFSET))
81 *dataoff = nhoff + (iph->ihl << 2);
82 *protonum = iph->protocol;
84 /* Check bogus IP headers */
85 if (*dataoff > skb->len) {
86 pr_debug("nf_conntrack_ipv4: bogus IPv4 packet: "
87 "nhoff %u, ihl %u, skblen %u\n",
88 nhoff, iph->ihl << 2, skb->len);
95 static unsigned int ipv4_helper(void *priv,
97 const struct nf_hook_state *state)
100 enum ip_conntrack_info ctinfo;
101 const struct nf_conn_help *help;
102 const struct nf_conntrack_helper *helper;
104 /* This is where we call the helper: as the packet goes out. */
105 ct = nf_ct_get(skb, &ctinfo);
106 if (!ct || ctinfo == IP_CT_RELATED_REPLY)
109 help = nfct_help(ct);
113 /* rcu_read_lock()ed by nf_hook_thresh */
114 helper = rcu_dereference(help->helper);
118 return helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
122 static unsigned int ipv4_confirm(void *priv,
124 const struct nf_hook_state *state)
127 enum ip_conntrack_info ctinfo;
129 ct = nf_ct_get(skb, &ctinfo);
130 if (!ct || ctinfo == IP_CT_RELATED_REPLY)
133 /* adjust seqs for loopback traffic only in outgoing direction */
134 if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
135 !nf_is_loopback_packet(skb)) {
136 if (!nf_ct_seq_adjust(skb, ct, ctinfo, ip_hdrlen(skb))) {
137 NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
142 /* We've seen it coming out the other side: confirm it */
143 return nf_conntrack_confirm(skb);
146 static unsigned int ipv4_conntrack_in(void *priv,
148 const struct nf_hook_state *state)
150 return nf_conntrack_in(state->net, PF_INET, state->hook, skb);
153 static unsigned int ipv4_conntrack_local(void *priv,
155 const struct nf_hook_state *state)
157 /* root is playing with raw sockets. */
158 if (skb->len < sizeof(struct iphdr) ||
159 ip_hdrlen(skb) < sizeof(struct iphdr))
162 if (ip_is_fragment(ip_hdr(skb))) { /* IP_NODEFRAG setsockopt set */
163 enum ip_conntrack_info ctinfo;
164 struct nf_conn *tmpl;
166 tmpl = nf_ct_get(skb, &ctinfo);
167 if (tmpl && nf_ct_is_template(tmpl)) {
168 /* when skipping ct, clear templates to avoid fooling
169 * later targets/matches
177 return nf_conntrack_in(state->net, PF_INET, state->hook, skb);
180 /* Connection tracking may drop packets, but never alters them, so
181 make it the first hook. */
182 static const struct nf_hook_ops ipv4_conntrack_ops[] = {
184 .hook = ipv4_conntrack_in,
186 .hooknum = NF_INET_PRE_ROUTING,
187 .priority = NF_IP_PRI_CONNTRACK,
190 .hook = ipv4_conntrack_local,
192 .hooknum = NF_INET_LOCAL_OUT,
193 .priority = NF_IP_PRI_CONNTRACK,
198 .hooknum = NF_INET_POST_ROUTING,
199 .priority = NF_IP_PRI_CONNTRACK_HELPER,
202 .hook = ipv4_confirm,
204 .hooknum = NF_INET_POST_ROUTING,
205 .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
210 .hooknum = NF_INET_LOCAL_IN,
211 .priority = NF_IP_PRI_CONNTRACK_HELPER,
214 .hook = ipv4_confirm,
216 .hooknum = NF_INET_LOCAL_IN,
217 .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
221 /* Fast function for those who don't want to parse /proc (and I don't
223 /* Reversing the socket's dst/src point of view gives us the reply
226 getorigdst(struct sock *sk, int optval, void __user *user, int *len)
228 const struct inet_sock *inet = inet_sk(sk);
229 const struct nf_conntrack_tuple_hash *h;
230 struct nf_conntrack_tuple tuple;
232 memset(&tuple, 0, sizeof(tuple));
235 tuple.src.u3.ip = inet->inet_rcv_saddr;
236 tuple.src.u.tcp.port = inet->inet_sport;
237 tuple.dst.u3.ip = inet->inet_daddr;
238 tuple.dst.u.tcp.port = inet->inet_dport;
239 tuple.src.l3num = PF_INET;
240 tuple.dst.protonum = sk->sk_protocol;
243 /* We only do TCP and SCTP at the moment: is there a better way? */
244 if (tuple.dst.protonum != IPPROTO_TCP &&
245 tuple.dst.protonum != IPPROTO_SCTP) {
246 pr_debug("SO_ORIGINAL_DST: Not a TCP/SCTP socket\n");
250 if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
251 pr_debug("SO_ORIGINAL_DST: len %d not %zu\n",
252 *len, sizeof(struct sockaddr_in));
256 h = nf_conntrack_find_get(sock_net(sk), &nf_ct_zone_dflt, &tuple);
258 struct sockaddr_in sin;
259 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
261 sin.sin_family = AF_INET;
262 sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
263 .tuple.dst.u.tcp.port;
264 sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
266 memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
268 pr_debug("SO_ORIGINAL_DST: %pI4 %u\n",
269 &sin.sin_addr.s_addr, ntohs(sin.sin_port));
271 if (copy_to_user(user, &sin, sizeof(sin)) != 0)
276 pr_debug("SO_ORIGINAL_DST: Can't find %pI4/%u-%pI4/%u.\n",
277 &tuple.src.u3.ip, ntohs(tuple.src.u.tcp.port),
278 &tuple.dst.u3.ip, ntohs(tuple.dst.u.tcp.port));
282 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
284 #include <linux/netfilter/nfnetlink.h>
285 #include <linux/netfilter/nfnetlink_conntrack.h>
287 static int ipv4_tuple_to_nlattr(struct sk_buff *skb,
288 const struct nf_conntrack_tuple *tuple)
290 if (nla_put_in_addr(skb, CTA_IP_V4_SRC, tuple->src.u3.ip) ||
291 nla_put_in_addr(skb, CTA_IP_V4_DST, tuple->dst.u3.ip))
292 goto nla_put_failure;
299 static const struct nla_policy ipv4_nla_policy[CTA_IP_MAX+1] = {
300 [CTA_IP_V4_SRC] = { .type = NLA_U32 },
301 [CTA_IP_V4_DST] = { .type = NLA_U32 },
304 static int ipv4_nlattr_to_tuple(struct nlattr *tb[],
305 struct nf_conntrack_tuple *t)
307 if (!tb[CTA_IP_V4_SRC] || !tb[CTA_IP_V4_DST])
310 t->src.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_SRC]);
311 t->dst.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_DST]);
317 static struct nf_sockopt_ops so_getorigdst = {
319 .get_optmin = SO_ORIGINAL_DST,
320 .get_optmax = SO_ORIGINAL_DST+1,
322 .owner = THIS_MODULE,
325 static int ipv4_hooks_register(struct net *net)
327 struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id);
330 mutex_lock(®ister_ipv4_hooks);
336 err = nf_defrag_ipv4_enable(net);
342 err = nf_register_net_hooks(net, ipv4_conntrack_ops,
343 ARRAY_SIZE(ipv4_conntrack_ops));
348 mutex_unlock(®ister_ipv4_hooks);
352 static void ipv4_hooks_unregister(struct net *net)
354 struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id);
356 mutex_lock(®ister_ipv4_hooks);
357 if (cnet->users && (--cnet->users == 0))
358 nf_unregister_net_hooks(net, ipv4_conntrack_ops,
359 ARRAY_SIZE(ipv4_conntrack_ops));
360 mutex_unlock(®ister_ipv4_hooks);
363 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
365 .pkt_to_tuple = ipv4_pkt_to_tuple,
366 .invert_tuple = ipv4_invert_tuple,
367 .get_l4proto = ipv4_get_l4proto,
368 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
369 .tuple_to_nlattr = ipv4_tuple_to_nlattr,
370 .nlattr_to_tuple = ipv4_nlattr_to_tuple,
371 .nla_policy = ipv4_nla_policy,
372 .nla_size = NLA_ALIGN(NLA_HDRLEN + sizeof(u32)) + /* CTA_IP_V4_SRC */
373 NLA_ALIGN(NLA_HDRLEN + sizeof(u32)), /* CTA_IP_V4_DST */
375 .net_ns_get = ipv4_hooks_register,
376 .net_ns_put = ipv4_hooks_unregister,
380 module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
381 &nf_conntrack_htable_size, 0600);
383 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
384 MODULE_ALIAS("ip_conntrack");
385 MODULE_LICENSE("GPL");
387 static struct nf_conntrack_l4proto *builtin_l4proto4[] = {
388 &nf_conntrack_l4proto_tcp4,
389 &nf_conntrack_l4proto_udp4,
390 &nf_conntrack_l4proto_icmp,
391 #ifdef CONFIG_NF_CT_PROTO_DCCP
392 &nf_conntrack_l4proto_dccp4,
394 #ifdef CONFIG_NF_CT_PROTO_SCTP
395 &nf_conntrack_l4proto_sctp4,
397 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
398 &nf_conntrack_l4proto_udplite4,
402 static int ipv4_net_init(struct net *net)
404 return nf_ct_l4proto_pernet_register(net, builtin_l4proto4,
405 ARRAY_SIZE(builtin_l4proto4));
408 static void ipv4_net_exit(struct net *net)
410 nf_ct_l4proto_pernet_unregister(net, builtin_l4proto4,
411 ARRAY_SIZE(builtin_l4proto4));
414 static struct pernet_operations ipv4_net_ops = {
415 .init = ipv4_net_init,
416 .exit = ipv4_net_exit,
417 .id = &conntrack4_net_id,
418 .size = sizeof(struct conntrack4_net),
421 static int __init nf_conntrack_l3proto_ipv4_init(void)
427 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
428 if (WARN_ON(nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1) !=
429 nf_conntrack_l3proto_ipv4.nla_size))
432 ret = nf_register_sockopt(&so_getorigdst);
434 pr_err("Unable to register netfilter socket option\n");
438 ret = register_pernet_subsys(&ipv4_net_ops);
440 pr_err("nf_conntrack_ipv4: can't register pernet ops\n");
441 goto cleanup_sockopt;
444 ret = nf_ct_l4proto_register(builtin_l4proto4,
445 ARRAY_SIZE(builtin_l4proto4));
449 ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv4);
451 pr_err("nf_conntrack_ipv4: can't register ipv4 proto.\n");
452 goto cleanup_l4proto;
457 nf_ct_l4proto_unregister(builtin_l4proto4,
458 ARRAY_SIZE(builtin_l4proto4));
460 unregister_pernet_subsys(&ipv4_net_ops);
462 nf_unregister_sockopt(&so_getorigdst);
466 static void __exit nf_conntrack_l3proto_ipv4_fini(void)
469 nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
470 nf_ct_l4proto_unregister(builtin_l4proto4,
471 ARRAY_SIZE(builtin_l4proto4));
472 unregister_pernet_subsys(&ipv4_net_ops);
473 nf_unregister_sockopt(&so_getorigdst);
476 module_init(nf_conntrack_l3proto_ipv4_init);
477 module_exit(nf_conntrack_l3proto_ipv4_fini);