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/config.h>
  18 #include <linux/types.h>
  19 #include <linux/ip.h>
  20 #include <linux/netfilter.h>
  21 #include <linux/module.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/icmp.h>
  24 #include <linux/sysctl.h>
  25 #include <net/route.h>
  26 #include <net/ip.h>
  27
  28 #include <linux/netfilter_ipv4.h>
  29 #include <net/netfilter/nf_conntrack.h>
  30 #include <net/netfilter/nf_conntrack_helper.h>
  31 #include <net/netfilter/nf_conntrack_protocol.h>
  32 #include <net/netfilter/nf_conntrack_l3proto.h>
  33 #include <net/netfilter/nf_conntrack_core.h>
  34 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  35
  36 #if 0
  37 #define DEBUGP printk
  38 #else
  39 #define DEBUGP(format, args...)
  40 #endif
  41
  42 DECLARE_PER_CPU(struct nf_conntrack_stat, nf_conntrack_stat);
  43
  44 static int ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  45                              struct nf_conntrack_tuple *tuple)
  46 {
  47         u_int32_t _addrs[2], *ap;
  48         ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
  49                                 sizeof(u_int32_t) * 2, _addrs);
  50         if (ap == NULL)
  51                 return 0;
  52
  53         tuple->src.u3.ip = ap[0];
  54         tuple->dst.u3.ip = ap[1];
  55
  56         return 1;
  57 }
  58
  59 static int ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
  60                            const struct nf_conntrack_tuple *orig)
  61 {
  62         tuple->src.u3.ip = orig->dst.u3.ip;
  63         tuple->dst.u3.ip = orig->src.u3.ip;
  64
  65         return 1;
  66 }
  67
  68 static int ipv4_print_tuple(struct seq_file *s,
  69                             const struct nf_conntrack_tuple *tuple)
  70 {
  71         return seq_printf(s, "src=%u.%u.%u.%u dst=%u.%u.%u.%u ",
  72                           NIPQUAD(tuple->src.u3.ip),
  73                           NIPQUAD(tuple->dst.u3.ip));
  74 }
  75
  76 static int ipv4_print_conntrack(struct seq_file *s,
  77                                 const struct nf_conn *conntrack)
  78 {
  79         return 0;
  80 }
  81
  82 /* Returns new sk_buff, or NULL */
  83 static struct sk_buff *
  84 nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
  85 {
  86         skb_orphan(skb);
  87
  88         local_bh_disable();
  89         skb = ip_defrag(skb, user);
  90         local_bh_enable();
  91
  92         if (skb)
  93                 ip_send_check(skb->nh.iph);
  94
  95         return skb;
  96 }
  97
  98 static int
  99 ipv4_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
 100              u_int8_t *protonum)
 101 {
 102         /* Never happen */
 103         if ((*pskb)->nh.iph->frag_off & htons(IP_OFFSET)) {
 104                 if (net_ratelimit()) {
 105                         printk(KERN_ERR "ipv4_prepare: Frag of proto %u (hook=%u)\n",
 106                         (*pskb)->nh.iph->protocol, hooknum);
 107                 }
 108                 return -NF_DROP;
 109         }
 110
 111         *dataoff = (*pskb)->nh.raw - (*pskb)->data + (*pskb)->nh.iph->ihl*4;
 112         *protonum = (*pskb)->nh.iph->protocol;
 113
 114         return NF_ACCEPT;
 115 }
 116
 117 int nat_module_is_loaded = 0;
 118 static u_int32_t ipv4_get_features(const struct nf_conntrack_tuple *tuple)
 119 {
 120         if (nat_module_is_loaded)
 121                 return NF_CT_F_NAT;
 122
 123         return NF_CT_F_BASIC;
 124 }
 125
 126 static unsigned int ipv4_confirm(unsigned int hooknum,
 127                                  struct sk_buff **pskb,
 128                                  const struct net_device *in,
 129                                  const struct net_device *out,
 130                                  int (*okfn)(struct sk_buff *))
 131 {
 132         /* We've seen it coming out the other side: confirm it */
 133         return nf_conntrack_confirm(pskb);
 134 }
 135
 136 static unsigned int ipv4_conntrack_help(unsigned int hooknum,
 137                                       struct sk_buff **pskb,
 138                                       const struct net_device *in,
 139                                       const struct net_device *out,
 140                                       int (*okfn)(struct sk_buff *))
 141 {
 142         struct nf_conn *ct;
 143         enum ip_conntrack_info ctinfo;
 144
 145         /* This is where we call the helper: as the packet goes out. */
 146         ct = nf_ct_get(*pskb, &ctinfo);
 147         if (ct && ct->helper) {
 148                 unsigned int ret;
 149                 ret = ct->helper->help(pskb,
 150                                        (*pskb)->nh.raw - (*pskb)->data
 151                                                        + (*pskb)->nh.iph->ihl*4,
 152                                        ct, ctinfo);
 153                 if (ret != NF_ACCEPT)
 154                         return ret;
 155         }
 156         return NF_ACCEPT;
 157 }
 158
 159 static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
 160                                           struct sk_buff **pskb,
 161                                           const struct net_device *in,
 162                                           const struct net_device *out,
 163                                           int (*okfn)(struct sk_buff *))
 164 {
 165 #if !defined(CONFIG_IP_NF_NAT) && !defined(CONFIG_IP_NF_NAT_MODULE)
 166         /* Previously seen (loopback)?  Ignore.  Do this before
 167            fragment check. */
 168         if ((*pskb)->nfct)
 169                 return NF_ACCEPT;
 170 #endif
 171
 172         /* Gather fragments. */
 173         if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
 174                 *pskb = nf_ct_ipv4_gather_frags(*pskb,
 175                                                 hooknum == NF_IP_PRE_ROUTING ?
 176                                                 IP_DEFRAG_CONNTRACK_IN :
 177                                                 IP_DEFRAG_CONNTRACK_OUT);
 178                 if (!*pskb)
 179                         return NF_STOLEN;
 180         }
 181         return NF_ACCEPT;
 182 }
 183
 184 static unsigned int ipv4_conntrack_in(unsigned int hooknum,
 185                                       struct sk_buff **pskb,
 186                                       const struct net_device *in,
 187                                       const struct net_device *out,
 188                                       int (*okfn)(struct sk_buff *))
 189 {
 190         return nf_conntrack_in(PF_INET, hooknum, pskb);
 191 }
 192
 193 static unsigned int ipv4_conntrack_local(unsigned int hooknum,
 194                                          struct sk_buff **pskb,
 195                                          const struct net_device *in,
 196                                          const struct net_device *out,
 197                                          int (*okfn)(struct sk_buff *))
 198 {
 199         /* root is playing with raw sockets. */
 200         if ((*pskb)->len < sizeof(struct iphdr)
 201             || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {
 202                 if (net_ratelimit())
 203                         printk("ipt_hook: happy cracking.\n");
 204                 return NF_ACCEPT;
 205         }
 206         return nf_conntrack_in(PF_INET, hooknum, pskb);
 207 }
 208
 209 /* Connection tracking may drop packets, but never alters them, so
 210    make it the first hook. */
 211 static struct nf_hook_ops ipv4_conntrack_defrag_ops = {
 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 static struct nf_hook_ops ipv4_conntrack_in_ops = {
 220         .hook           = ipv4_conntrack_in,
 221         .owner          = THIS_MODULE,
 222         .pf             = PF_INET,
 223         .hooknum        = NF_IP_PRE_ROUTING,
 224         .priority       = NF_IP_PRI_CONNTRACK,
 225 };
 226
 227 static struct nf_hook_ops ipv4_conntrack_defrag_local_out_ops = {
 228         .hook           = ipv4_conntrack_defrag,
 229         .owner          = THIS_MODULE,
 230         .pf             = PF_INET,
 231         .hooknum        = NF_IP_LOCAL_OUT,
 232         .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
 233 };
 234
 235 static struct nf_hook_ops ipv4_conntrack_local_out_ops = {
 236         .hook           = ipv4_conntrack_local,
 237         .owner          = THIS_MODULE,
 238         .pf             = PF_INET,
 239         .hooknum        = NF_IP_LOCAL_OUT,
 240         .priority       = NF_IP_PRI_CONNTRACK,
 241 };
 242
 243 /* helpers */
 244 static struct nf_hook_ops ipv4_conntrack_helper_out_ops = {
 245         .hook           = ipv4_conntrack_help,
 246         .owner          = THIS_MODULE,
 247         .pf             = PF_INET,
 248         .hooknum        = NF_IP_POST_ROUTING,
 249         .priority       = NF_IP_PRI_CONNTRACK_HELPER,
 250 };
 251
 252 static struct nf_hook_ops ipv4_conntrack_helper_in_ops = {
 253         .hook           = ipv4_conntrack_help,
 254         .owner          = THIS_MODULE,
 255         .pf             = PF_INET,
 256         .hooknum        = NF_IP_LOCAL_IN,
 257         .priority       = NF_IP_PRI_CONNTRACK_HELPER,
 258 };
 259
 260
 261 /* Refragmenter; last chance. */
 262 static struct nf_hook_ops ipv4_conntrack_out_ops = {
 263         .hook           = ipv4_confirm,
 264         .owner          = THIS_MODULE,
 265         .pf             = PF_INET,
 266         .hooknum        = NF_IP_POST_ROUTING,
 267         .priority       = NF_IP_PRI_CONNTRACK_CONFIRM,
 268 };
 269
 270 static struct nf_hook_ops ipv4_conntrack_local_in_ops = {
 271         .hook           = ipv4_confirm,
 272         .owner          = THIS_MODULE,
 273         .pf             = PF_INET,
 274         .hooknum        = NF_IP_LOCAL_IN,
 275         .priority       = NF_IP_PRI_CONNTRACK_CONFIRM,
 276 };
 277
 278 #ifdef CONFIG_SYSCTL
 279 /* From nf_conntrack_proto_icmp.c */
 280 extern unsigned int nf_ct_icmp_timeout;
 281 static struct ctl_table_header *nf_ct_ipv4_sysctl_header;
 282
 283 static ctl_table nf_ct_sysctl_table[] = {
 284         {
 285                 .ctl_name       = NET_NF_CONNTRACK_ICMP_TIMEOUT,
 286                 .procname       = "nf_conntrack_icmp_timeout",
 287                 .data           = &nf_ct_icmp_timeout,
 288                 .maxlen         = sizeof(unsigned int),
 289                 .mode           = 0644,
 290                 .proc_handler   = &proc_dointvec_jiffies,
 291         },
 292         { .ctl_name = 0 }
 293 };
 294
 295 static ctl_table nf_ct_netfilter_table[] = {
 296         {
 297                 .ctl_name       = NET_NETFILTER,
 298                 .procname       = "netfilter",
 299                 .mode           = 0555,
 300                 .child          = nf_ct_sysctl_table,
 301         },
 302         { .ctl_name = 0 }
 303 };
 304
 305 static ctl_table nf_ct_net_table[] = {
 306         {
 307                 .ctl_name       = CTL_NET,
 308                 .procname       = "net",
 309                 .mode           = 0555,
 310                 .child          = nf_ct_netfilter_table,
 311         },
 312         { .ctl_name = 0 }
 313 };
 314 #endif
 315
 316 /* Fast function for those who don't want to parse /proc (and I don't
 317    blame them). */
 318 /* Reversing the socket's dst/src point of view gives us the reply
 319    mapping. */
 320 static int
 321 getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 322 {
 323         struct inet_sock *inet = inet_sk(sk);
 324         struct nf_conntrack_tuple_hash *h;
 325         struct nf_conntrack_tuple tuple;
 326
 327         NF_CT_TUPLE_U_BLANK(&tuple);
 328         tuple.src.u3.ip = inet->rcv_saddr;
 329         tuple.src.u.tcp.port = inet->sport;
 330         tuple.dst.u3.ip = inet->daddr;
 331         tuple.dst.u.tcp.port = inet->dport;
 332         tuple.src.l3num = PF_INET;
 333         tuple.dst.protonum = IPPROTO_TCP;
 334
 335         /* We only do TCP at the moment: is there a better way? */
 336         if (strcmp(sk->sk_prot->name, "TCP")) {
 337                 DEBUGP("SO_ORIGINAL_DST: Not a TCP socket\n");
 338                 return -ENOPROTOOPT;
 339         }
 340
 341         if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
 342                 DEBUGP("SO_ORIGINAL_DST: len %u not %u\n",
 343                        *len, sizeof(struct sockaddr_in));
 344                 return -EINVAL;
 345         }
 346
 347         h = nf_conntrack_find_get(&tuple, NULL);
 348         if (h) {
 349                 struct sockaddr_in sin;
 350                 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
 351
 352                 sin.sin_family = AF_INET;
 353                 sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
 354                         .tuple.dst.u.tcp.port;
 355                 sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
 356                         .tuple.dst.u3.ip;
 357                 memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
 358
 359                 DEBUGP("SO_ORIGINAL_DST: %u.%u.%u.%u %u\n",
 360                        NIPQUAD(sin.sin_addr.s_addr), ntohs(sin.sin_port));
 361                 nf_ct_put(ct);
 362                 if (copy_to_user(user, &sin, sizeof(sin)) != 0)
 363                         return -EFAULT;
 364                 else
 365                         return 0;
 366         }
 367         DEBUGP("SO_ORIGINAL_DST: Can't find %u.%u.%u.%u/%u-%u.%u.%u.%u/%u.\n",
 368                NIPQUAD(tuple.src.u3.ip), ntohs(tuple.src.u.tcp.port),
 369                NIPQUAD(tuple.dst.u3.ip), ntohs(tuple.dst.u.tcp.port));
 370         return -ENOENT;
 371 }
 372
 373 #if defined(CONFIG_NF_CT_NETLINK) || \
 374     defined(CONFIG_NF_CT_NETLINK_MODULE)
 375
 376 #include <linux/netfilter/nfnetlink.h>
 377 #include <linux/netfilter/nfnetlink_conntrack.h>
 378
 379 static int ipv4_tuple_to_nfattr(struct sk_buff *skb,
 380                                 const struct nf_conntrack_tuple *tuple)
 381 {
 382         NFA_PUT(skb, CTA_IP_V4_SRC, sizeof(u_int32_t),
 383                 &tuple->src.u3.ip);
 384         NFA_PUT(skb, CTA_IP_V4_DST, sizeof(u_int32_t),
 385                 &tuple->dst.u3.ip);
 386         return 0;
 387
 388 nfattr_failure:
 389         return -1;
 390 }
 391
 392 static const size_t cta_min_ip[CTA_IP_MAX] = {
 393         [CTA_IP_V4_SRC-1]       = sizeof(u_int32_t),
 394         [CTA_IP_V4_DST-1]       = sizeof(u_int32_t),
 395 };
 396
 397 static int ipv4_nfattr_to_tuple(struct nfattr *tb[],
 398                                 struct nf_conntrack_tuple *t)
 399 {
 400         if (!tb[CTA_IP_V4_SRC-1] || !tb[CTA_IP_V4_DST-1])
 401                 return -EINVAL;
 402
 403         if (nfattr_bad_size(tb, CTA_IP_MAX, cta_min_ip))
 404                 return -EINVAL;
 405
 406         t->src.u3.ip =
 407                 *(u_int32_t *)NFA_DATA(tb[CTA_IP_V4_SRC-1]);
 408         t->dst.u3.ip =
 409                 *(u_int32_t *)NFA_DATA(tb[CTA_IP_V4_DST-1]);
 410
 411         return 0;
 412 }
 413 #endif
 414
 415 static struct nf_sockopt_ops so_getorigdst = {
 416         .pf             = PF_INET,
 417         .get_optmin     = SO_ORIGINAL_DST,
 418         .get_optmax     = SO_ORIGINAL_DST+1,
 419         .get            = &getorigdst,
 420 };
 421
 422 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 = {
 423         .l3proto         = PF_INET,
 424         .name            = "ipv4",
 425         .pkt_to_tuple    = ipv4_pkt_to_tuple,
 426         .invert_tuple    = ipv4_invert_tuple,
 427         .print_tuple     = ipv4_print_tuple,
 428         .print_conntrack = ipv4_print_conntrack,
 429         .prepare         = ipv4_prepare,
 430         .get_features    = ipv4_get_features,
 431 #if defined(CONFIG_NF_CT_NETLINK) || \
 432     defined(CONFIG_NF_CT_NETLINK_MODULE)
 433         .tuple_to_nfattr = ipv4_tuple_to_nfattr,
 434         .nfattr_to_tuple = ipv4_nfattr_to_tuple,
 435 #endif
 436         .me              = THIS_MODULE,
 437 };
 438
 439 extern struct nf_conntrack_protocol nf_conntrack_protocol_tcp4;
 440 extern struct nf_conntrack_protocol nf_conntrack_protocol_udp4;
 441 extern struct nf_conntrack_protocol nf_conntrack_protocol_icmp;
 442 static int init_or_cleanup(int init)
 443 {
 444         int ret = 0;
 445
 446         if (!init) goto cleanup;
 447
 448         ret = nf_register_sockopt(&so_getorigdst);
 449         if (ret < 0) {
 450                 printk(KERN_ERR "Unable to register netfilter socket option\n");
 451                 goto cleanup_nothing;
 452         }
 453
 454         ret = nf_conntrack_protocol_register(&nf_conntrack_protocol_tcp4);
 455         if (ret < 0) {
 456                 printk("nf_conntrack_ipv4: can't register tcp.\n");
 457                 goto cleanup_sockopt;
 458         }
 459
 460         ret = nf_conntrack_protocol_register(&nf_conntrack_protocol_udp4);
 461         if (ret < 0) {
 462                 printk("nf_conntrack_ipv4: can't register udp.\n");
 463                 goto cleanup_tcp;
 464         }
 465
 466         ret = nf_conntrack_protocol_register(&nf_conntrack_protocol_icmp);
 467         if (ret < 0) {
 468                 printk("nf_conntrack_ipv4: can't register icmp.\n");
 469                 goto cleanup_udp;
 470         }
 471
 472         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv4);
 473         if (ret < 0) {
 474                 printk("nf_conntrack_ipv4: can't register ipv4\n");
 475                 goto cleanup_icmp;
 476         }
 477
 478         ret = nf_register_hook(&ipv4_conntrack_defrag_ops);
 479         if (ret < 0) {
 480                 printk("nf_conntrack_ipv4: can't register pre-routing defrag hook.\n");
 481                 goto cleanup_ipv4;
 482         }
 483         ret = nf_register_hook(&ipv4_conntrack_defrag_local_out_ops);
 484         if (ret < 0) {
 485                 printk("nf_conntrack_ipv4: can't register local_out defrag hook.\n");
 486                 goto cleanup_defragops;
 487         }
 488
 489         ret = nf_register_hook(&ipv4_conntrack_in_ops);
 490         if (ret < 0) {
 491                 printk("nf_conntrack_ipv4: can't register pre-routing hook.\n");
 492                 goto cleanup_defraglocalops;
 493         }
 494
 495         ret = nf_register_hook(&ipv4_conntrack_local_out_ops);
 496         if (ret < 0) {
 497                 printk("nf_conntrack_ipv4: can't register local out hook.\n");
 498                 goto cleanup_inops;
 499         }
 500
 501         ret = nf_register_hook(&ipv4_conntrack_helper_in_ops);
 502         if (ret < 0) {
 503                 printk("nf_conntrack_ipv4: can't register local helper hook.\n");
 504                 goto cleanup_inandlocalops;
 505         }
 506
 507         ret = nf_register_hook(&ipv4_conntrack_helper_out_ops);
 508         if (ret < 0) {
 509                 printk("nf_conntrack_ipv4: can't register postrouting helper hook.\n");
 510                 goto cleanup_helperinops;
 511         }
 512
 513         ret = nf_register_hook(&ipv4_conntrack_out_ops);
 514         if (ret < 0) {
 515                 printk("nf_conntrack_ipv4: can't register post-routing hook.\n");
 516                 goto cleanup_helperoutops;
 517         }
 518
 519         ret = nf_register_hook(&ipv4_conntrack_local_in_ops);
 520         if (ret < 0) {
 521                 printk("nf_conntrack_ipv4: can't register local in hook.\n");
 522                 goto cleanup_inoutandlocalops;
 523         }
 524
 525 #ifdef CONFIG_SYSCTL
 526         nf_ct_ipv4_sysctl_header = register_sysctl_table(nf_ct_net_table, 0);
 527         if (nf_ct_ipv4_sysctl_header == NULL) {
 528                 printk("nf_conntrack: can't register to sysctl.\n");
 529                 ret = -ENOMEM;
 530                 goto cleanup_localinops;
 531         }
 532 #endif
 533         return ret;
 534
 535  cleanup:
 536         synchronize_net();
 537 #ifdef CONFIG_SYSCTL
 538         unregister_sysctl_table(nf_ct_ipv4_sysctl_header);
 539  cleanup_localinops:
 540 #endif
 541         nf_unregister_hook(&ipv4_conntrack_local_in_ops);
 542  cleanup_inoutandlocalops:
 543         nf_unregister_hook(&ipv4_conntrack_out_ops);
 544  cleanup_helperoutops:
 545         nf_unregister_hook(&ipv4_conntrack_helper_out_ops);
 546  cleanup_helperinops:
 547         nf_unregister_hook(&ipv4_conntrack_helper_in_ops);
 548  cleanup_inandlocalops:
 549         nf_unregister_hook(&ipv4_conntrack_local_out_ops);
 550  cleanup_inops:
 551         nf_unregister_hook(&ipv4_conntrack_in_ops);
 552  cleanup_defraglocalops:
 553         nf_unregister_hook(&ipv4_conntrack_defrag_local_out_ops);
 554  cleanup_defragops:
 555         nf_unregister_hook(&ipv4_conntrack_defrag_ops);
 556  cleanup_ipv4:
 557         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
 558  cleanup_icmp:
 559         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_icmp);
 560  cleanup_udp:
 561         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_udp4);
 562  cleanup_tcp:
 563         nf_conntrack_protocol_unregister(&nf_conntrack_protocol_tcp4);
 564  cleanup_sockopt:
 565         nf_unregister_sockopt(&so_getorigdst);
 566  cleanup_nothing:
 567         return ret;
 568 }
 569
 570 MODULE_LICENSE("GPL");
 571
 572 static int __init init(void)
 573 {
 574         need_conntrack();
 575         return init_or_cleanup(1);
 576 }
 577
 578 static void __exit fini(void)
 579 {
 580         init_or_cleanup(0);
 581 }
 582
 583 module_init(init);
 584 module_exit(fini);
 585
 586 EXPORT_SYMBOL(nf_ct_ipv4_gather_frags);