~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c

Version: ~ [ linux-5.14-rc1 ] ~ [ linux-5.13.1 ] ~ [ linux-5.12.16 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.49 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.131 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.197 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.239 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.275 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.275 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 
  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>
  5  *
  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.
  9  */
 10 
 11 #include <linux/types.h>
 12 #include <linux/ip.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>
 19 #include <net/ip.h>
 20 
 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>
 33 
 34 static int conntrack4_net_id __read_mostly;
 35 static DEFINE_MUTEX(register_ipv4_hooks);
 36 
 37 struct conntrack4_net {
 38         unsigned int users;
 39 };
 40 
 41 static bool ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
 42                               struct nf_conntrack_tuple *tuple)
 43 {
 44         const __be32 *ap;
 45         __be32 _addrs[2];
 46         ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
 47                                 sizeof(u_int32_t) * 2, _addrs);
 48         if (ap == NULL)
 49                 return false;
 50 
 51         tuple->src.u3.ip = ap[0];
 52         tuple->dst.u3.ip = ap[1];
 53 
 54         return true;
 55 }
 56 
 57 static bool ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
 58                               const struct nf_conntrack_tuple *orig)
 59 {
 60         tuple->src.u3.ip = orig->dst.u3.ip;
 61         tuple->dst.u3.ip = orig->src.u3.ip;
 62 
 63         return true;
 64 }
 65 
 66 static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
 67                             unsigned int *dataoff, u_int8_t *protonum)
 68 {
 69         const struct iphdr *iph;
 70         struct iphdr _iph;
 71 
 72         iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
 73         if (iph == NULL)
 74                 return -NF_ACCEPT;
 75 
 76         /* Conntrack defragments packets, we might still see fragments
 77          * inside ICMP packets though. */
 78         if (iph->frag_off & htons(IP_OFFSET))
 79                 return -NF_ACCEPT;
 80 
 81         *dataoff = nhoff + (iph->ihl << 2);
 82         *protonum = iph->protocol;
 83 
 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);
 89                 return -NF_ACCEPT;
 90         }
 91 
 92         return NF_ACCEPT;
 93 }
 94 
 95 static unsigned int ipv4_helper(void *priv,
 96                                 struct sk_buff *skb,
 97                                 const struct nf_hook_state *state)
 98 {
 99         struct nf_conn *ct;
100         enum ip_conntrack_info ctinfo;
101         const struct nf_conn_help *help;
102         const struct nf_conntrack_helper *helper;
103 
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)
107                 return NF_ACCEPT;
108 
109         help = nfct_help(ct);
110         if (!help)
111                 return NF_ACCEPT;
112 
113         /* rcu_read_lock()ed by nf_hook_thresh */
114         helper = rcu_dereference(help->helper);
115         if (!helper)
116                 return NF_ACCEPT;
117 
118         return helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
119                             ct, ctinfo);
120 }
121 
122 static unsigned int ipv4_confirm(void *priv,
123                                  struct sk_buff *skb,
124                                  const struct nf_hook_state *state)
125 {
126         struct nf_conn *ct;
127         enum ip_conntrack_info ctinfo;
128 
129         ct = nf_ct_get(skb, &ctinfo);
130         if (!ct || ctinfo == IP_CT_RELATED_REPLY)
131                 goto out;
132 
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);
138                         return NF_DROP;
139                 }
140         }
141 out:
142         /* We've seen it coming out the other side: confirm it */
143         return nf_conntrack_confirm(skb);
144 }
145 
146 static unsigned int ipv4_conntrack_in(void *priv,
147                                       struct sk_buff *skb,
148                                       const struct nf_hook_state *state)
149 {
150         return nf_conntrack_in(state->net, PF_INET, state->hook, skb);
151 }
152 
153 static unsigned int ipv4_conntrack_local(void *priv,
154                                          struct sk_buff *skb,
155                                          const struct nf_hook_state *state)
156 {
157         if (ip_is_fragment(ip_hdr(skb))) { /* IP_NODEFRAG setsockopt set */
158                 enum ip_conntrack_info ctinfo;
159                 struct nf_conn *tmpl;
160 
161                 tmpl = nf_ct_get(skb, &ctinfo);
162                 if (tmpl && nf_ct_is_template(tmpl)) {
163                         /* when skipping ct, clear templates to avoid fooling
164                          * later targets/matches
165                          */
166                         skb->_nfct = 0;
167                         nf_ct_put(tmpl);
168                 }
169                 return NF_ACCEPT;
170         }
171 
172         return nf_conntrack_in(state->net, PF_INET, state->hook, skb);
173 }
174 
175 /* Connection tracking may drop packets, but never alters them, so
176    make it the first hook. */
177 static const struct nf_hook_ops ipv4_conntrack_ops[] = {
178         {
179                 .hook           = ipv4_conntrack_in,
180                 .pf             = NFPROTO_IPV4,
181                 .hooknum        = NF_INET_PRE_ROUTING,
182                 .priority       = NF_IP_PRI_CONNTRACK,
183         },
184         {
185                 .hook           = ipv4_conntrack_local,
186                 .pf             = NFPROTO_IPV4,
187                 .hooknum        = NF_INET_LOCAL_OUT,
188                 .priority       = NF_IP_PRI_CONNTRACK,
189         },
190         {
191                 .hook           = ipv4_helper,
192                 .pf             = NFPROTO_IPV4,
193                 .hooknum        = NF_INET_POST_ROUTING,
194                 .priority       = NF_IP_PRI_CONNTRACK_HELPER,
195         },
196         {
197                 .hook           = ipv4_confirm,
198                 .pf             = NFPROTO_IPV4,
199                 .hooknum        = NF_INET_POST_ROUTING,
200                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM,
201         },
202         {
203                 .hook           = ipv4_helper,
204                 .pf             = NFPROTO_IPV4,
205                 .hooknum        = NF_INET_LOCAL_IN,
206                 .priority       = NF_IP_PRI_CONNTRACK_HELPER,
207         },
208         {
209                 .hook           = ipv4_confirm,
210                 .pf             = NFPROTO_IPV4,
211                 .hooknum        = NF_INET_LOCAL_IN,
212                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM,
213         },
214 };
215 
216 /* Fast function for those who don't want to parse /proc (and I don't
217    blame them). */
218 /* Reversing the socket's dst/src point of view gives us the reply
219    mapping. */
220 static int
221 getorigdst(struct sock *sk, int optval, void __user *user, int *len)
222 {
223         const struct inet_sock *inet = inet_sk(sk);
224         const struct nf_conntrack_tuple_hash *h;
225         struct nf_conntrack_tuple tuple;
226 
227         memset(&tuple, 0, sizeof(tuple));
228 
229         lock_sock(sk);
230         tuple.src.u3.ip = inet->inet_rcv_saddr;
231         tuple.src.u.tcp.port = inet->inet_sport;
232         tuple.dst.u3.ip = inet->inet_daddr;
233         tuple.dst.u.tcp.port = inet->inet_dport;
234         tuple.src.l3num = PF_INET;
235         tuple.dst.protonum = sk->sk_protocol;
236         release_sock(sk);
237 
238         /* We only do TCP and SCTP at the moment: is there a better way? */
239         if (tuple.dst.protonum != IPPROTO_TCP &&
240             tuple.dst.protonum != IPPROTO_SCTP) {
241                 pr_debug("SO_ORIGINAL_DST: Not a TCP/SCTP socket\n");
242                 return -ENOPROTOOPT;
243         }
244 
245         if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
246                 pr_debug("SO_ORIGINAL_DST: len %d not %zu\n",
247                          *len, sizeof(struct sockaddr_in));
248                 return -EINVAL;
249         }
250 
251         h = nf_conntrack_find_get(sock_net(sk), &nf_ct_zone_dflt, &tuple);
252         if (h) {
253                 struct sockaddr_in sin;
254                 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
255 
256                 sin.sin_family = AF_INET;
257                 sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
258                         .tuple.dst.u.tcp.port;
259                 sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
260                         .tuple.dst.u3.ip;
261                 memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
262 
263                 pr_debug("SO_ORIGINAL_DST: %pI4 %u\n",
264                          &sin.sin_addr.s_addr, ntohs(sin.sin_port));
265                 nf_ct_put(ct);
266                 if (copy_to_user(user, &sin, sizeof(sin)) != 0)
267                         return -EFAULT;
268                 else
269                         return 0;
270         }
271         pr_debug("SO_ORIGINAL_DST: Can't find %pI4/%u-%pI4/%u.\n",
272                  &tuple.src.u3.ip, ntohs(tuple.src.u.tcp.port),
273                  &tuple.dst.u3.ip, ntohs(tuple.dst.u.tcp.port));
274         return -ENOENT;
275 }
276 
277 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
278 
279 #include <linux/netfilter/nfnetlink.h>
280 #include <linux/netfilter/nfnetlink_conntrack.h>
281 
282 static int ipv4_tuple_to_nlattr(struct sk_buff *skb,
283                                 const struct nf_conntrack_tuple *tuple)
284 {
285         if (nla_put_in_addr(skb, CTA_IP_V4_SRC, tuple->src.u3.ip) ||
286             nla_put_in_addr(skb, CTA_IP_V4_DST, tuple->dst.u3.ip))
287                 goto nla_put_failure;
288         return 0;
289 
290 nla_put_failure:
291         return -1;
292 }
293 
294 static const struct nla_policy ipv4_nla_policy[CTA_IP_MAX+1] = {
295         [CTA_IP_V4_SRC] = { .type = NLA_U32 },
296         [CTA_IP_V4_DST] = { .type = NLA_U32 },
297 };
298 
299 static int ipv4_nlattr_to_tuple(struct nlattr *tb[],
300                                 struct nf_conntrack_tuple *t)
301 {
302         if (!tb[CTA_IP_V4_SRC] || !tb[CTA_IP_V4_DST])
303                 return -EINVAL;
304 
305         t->src.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_SRC]);
306         t->dst.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_DST]);
307 
308         return 0;
309 }
310 #endif
311 
312 static struct nf_sockopt_ops so_getorigdst = {
313         .pf             = PF_INET,
314         .get_optmin     = SO_ORIGINAL_DST,
315         .get_optmax     = SO_ORIGINAL_DST+1,
316         .get            = getorigdst,
317         .owner          = THIS_MODULE,
318 };
319 
320 static int ipv4_hooks_register(struct net *net)
321 {
322         struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id);
323         int err = 0;
324 
325         mutex_lock(&register_ipv4_hooks);
326 
327         cnet->users++;
328         if (cnet->users > 1)
329                 goto out_unlock;
330 
331         err = nf_defrag_ipv4_enable(net);
332         if (err) {
333                 cnet->users = 0;
334                 goto out_unlock;
335         }
336 
337         err = nf_register_net_hooks(net, ipv4_conntrack_ops,
338                                     ARRAY_SIZE(ipv4_conntrack_ops));
339 
340         if (err)
341                 cnet->users = 0;
342  out_unlock:
343         mutex_unlock(&register_ipv4_hooks);
344         return err;
345 }
346 
347 static void ipv4_hooks_unregister(struct net *net)
348 {
349         struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id);
350 
351         mutex_lock(&register_ipv4_hooks);
352         if (cnet->users && (--cnet->users == 0))
353                 nf_unregister_net_hooks(net, ipv4_conntrack_ops,
354                                         ARRAY_SIZE(ipv4_conntrack_ops));
355         mutex_unlock(&register_ipv4_hooks);
356 }
357 
358 const struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 = {
359         .l3proto         = PF_INET,
360         .pkt_to_tuple    = ipv4_pkt_to_tuple,
361         .invert_tuple    = ipv4_invert_tuple,
362         .get_l4proto     = ipv4_get_l4proto,
363 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
364         .tuple_to_nlattr = ipv4_tuple_to_nlattr,
365         .nlattr_to_tuple = ipv4_nlattr_to_tuple,
366         .nla_policy      = ipv4_nla_policy,
367         .nla_size        = NLA_ALIGN(NLA_HDRLEN + sizeof(u32)) + /* CTA_IP_V4_SRC */
368                            NLA_ALIGN(NLA_HDRLEN + sizeof(u32)),  /* CTA_IP_V4_DST */
369 #endif
370         .net_ns_get      = ipv4_hooks_register,
371         .net_ns_put      = ipv4_hooks_unregister,
372         .me              = THIS_MODULE,
373 };
374 
375 module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
376                   &nf_conntrack_htable_size, 0600);
377 
378 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
379 MODULE_ALIAS("ip_conntrack");
380 MODULE_LICENSE("GPL");
381 
382 static const struct nf_conntrack_l4proto * const builtin_l4proto4[] = {
383         &nf_conntrack_l4proto_tcp4,
384         &nf_conntrack_l4proto_udp4,
385         &nf_conntrack_l4proto_icmp,
386 #ifdef CONFIG_NF_CT_PROTO_DCCP
387         &nf_conntrack_l4proto_dccp4,
388 #endif
389 #ifdef CONFIG_NF_CT_PROTO_SCTP
390         &nf_conntrack_l4proto_sctp4,
391 #endif
392 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
393         &nf_conntrack_l4proto_udplite4,
394 #endif
395 };
396 
397 static int ipv4_net_init(struct net *net)
398 {
399         return nf_ct_l4proto_pernet_register(net, builtin_l4proto4,
400                                              ARRAY_SIZE(builtin_l4proto4));
401 }
402 
403 static void ipv4_net_exit(struct net *net)
404 {
405         nf_ct_l4proto_pernet_unregister(net, builtin_l4proto4,
406                                         ARRAY_SIZE(builtin_l4proto4));
407 }
408 
409 static struct pernet_operations ipv4_net_ops = {
410         .init = ipv4_net_init,
411         .exit = ipv4_net_exit,
412         .id = &conntrack4_net_id,
413         .size = sizeof(struct conntrack4_net),
414 };
415 
416 static int __init nf_conntrack_l3proto_ipv4_init(void)
417 {
418         int ret = 0;
419 
420         need_conntrack();
421 
422 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
423         if (WARN_ON(nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1) !=
424             nf_conntrack_l3proto_ipv4.nla_size))
425                 return -EINVAL;
426 #endif
427         ret = nf_register_sockopt(&so_getorigdst);
428         if (ret < 0) {
429                 pr_err("Unable to register netfilter socket option\n");
430                 return ret;
431         }
432 
433         ret = register_pernet_subsys(&ipv4_net_ops);
434         if (ret < 0) {
435                 pr_err("nf_conntrack_ipv4: can't register pernet ops\n");
436                 goto cleanup_sockopt;
437         }
438 
439         ret = nf_ct_l4proto_register(builtin_l4proto4,
440                                      ARRAY_SIZE(builtin_l4proto4));
441         if (ret < 0)
442                 goto cleanup_pernet;
443 
444         ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv4);
445         if (ret < 0) {
446                 pr_err("nf_conntrack_ipv4: can't register ipv4 proto.\n");
447                 goto cleanup_l4proto;
448         }
449 
450         return ret;
451 cleanup_l4proto:
452         nf_ct_l4proto_unregister(builtin_l4proto4,
453                                  ARRAY_SIZE(builtin_l4proto4));
454  cleanup_pernet:
455         unregister_pernet_subsys(&ipv4_net_ops);
456  cleanup_sockopt:
457         nf_unregister_sockopt(&so_getorigdst);
458         return ret;
459 }
460 
461 static void __exit nf_conntrack_l3proto_ipv4_fini(void)
462 {
463         synchronize_net();
464         nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
465         nf_ct_l4proto_unregister(builtin_l4proto4,
466                                  ARRAY_SIZE(builtin_l4proto4));
467         unregister_pernet_subsys(&ipv4_net_ops);
468         nf_unregister_sockopt(&so_getorigdst);
469 }
470 
471 module_init(nf_conntrack_l3proto_ipv4_init);
472 module_exit(nf_conntrack_l3proto_ipv4_fini);
473 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp