net/ipv6/sit.c

   1 /*
   2  *      IPv6 over IPv4 tunnel device - Simple Internet Transition (SIT)
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *      Changes:
  15  * Roger Venning <r.venning@telstra.com>:       6to4 support
  16  * Nate Thompson <nate@thebog.net>:             6to4 support
  17  * Fred Templin <fred.l.templin@boeing.com>:    isatap support
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/capability.h>
  22 #include <linux/errno.h>
  23 #include <linux/types.h>
  24 #include <linux/socket.h>
  25 #include <linux/sockios.h>
  26 #include <linux/net.h>
  27 #include <linux/in6.h>
  28 #include <linux/netdevice.h>
  29 #include <linux/if_arp.h>
  30 #include <linux/icmp.h>
  31 #include <linux/slab.h>
  32 #include <asm/uaccess.h>
  33 #include <linux/init.h>
  34 #include <linux/netfilter_ipv4.h>
  35 #include <linux/if_ether.h>
  36
  37 #include <net/sock.h>
  38 #include <net/snmp.h>
  39
  40 #include <net/ipv6.h>
  41 #include <net/protocol.h>
  42 #include <net/transp_v6.h>
  43 #include <net/ip6_fib.h>
  44 #include <net/ip6_route.h>
  45 #include <net/ndisc.h>
  46 #include <net/addrconf.h>
  47 #include <net/ip.h>
  48 #include <net/udp.h>
  49 #include <net/icmp.h>
  50 #include <net/ipip.h>
  51 #include <net/inet_ecn.h>
  52 #include <net/xfrm.h>
  53 #include <net/dsfield.h>
  54 #include <net/net_namespace.h>
  55 #include <net/netns/generic.h>
  56
  57 /*
  58    This version of net/ipv6/sit.c is cloned of net/ipv4/ip_gre.c
  59
  60    For comments look at net/ipv4/ip_gre.c --ANK
  61  */
  62
  63 #define HASH_SIZE  16
  64 #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
  65
  66 static int ipip6_tunnel_init(struct net_device *dev);
  67 static void ipip6_tunnel_setup(struct net_device *dev);
  68 static void ipip6_dev_free(struct net_device *dev);
  69
  70 static int sit_net_id __read_mostly;
  71 struct sit_net {
  72         struct ip_tunnel __rcu *tunnels_r_l[HASH_SIZE];
  73         struct ip_tunnel __rcu *tunnels_r[HASH_SIZE];
  74         struct ip_tunnel __rcu *tunnels_l[HASH_SIZE];
  75         struct ip_tunnel __rcu *tunnels_wc[1];
  76         struct ip_tunnel __rcu **tunnels[4];
  77
  78         struct net_device *fb_tunnel_dev;
  79 };
  80
  81 /*
  82  * Locking : hash tables are protected by RCU and RTNL
  83  */
  84
  85 #define for_each_ip_tunnel_rcu(start) \
  86         for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
  87
  88 /* often modified stats are per cpu, other are shared (netdev->stats) */
  89 struct pcpu_tstats {
  90         unsigned long   rx_packets;
  91         unsigned long   rx_bytes;
  92         unsigned long   tx_packets;
  93         unsigned long   tx_bytes;
  94 };
  95
  96 static struct net_device_stats *ipip6_get_stats(struct net_device *dev)
  97 {
  98         struct pcpu_tstats sum = { 0 };
  99         int i;
 100
 101         for_each_possible_cpu(i) {
 102                 const struct pcpu_tstats *tstats = per_cpu_ptr(dev->tstats, i);
 103
 104                 sum.rx_packets += tstats->rx_packets;
 105                 sum.rx_bytes   += tstats->rx_bytes;
 106                 sum.tx_packets += tstats->tx_packets;
 107                 sum.tx_bytes   += tstats->tx_bytes;
 108         }
 109         dev->stats.rx_packets = sum.rx_packets;
 110         dev->stats.rx_bytes   = sum.rx_bytes;
 111         dev->stats.tx_packets = sum.tx_packets;
 112         dev->stats.tx_bytes   = sum.tx_bytes;
 113         return &dev->stats;
 114 }
 115 /*
 116  * Must be invoked with rcu_read_lock
 117  */
 118 static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,
 119                 struct net_device *dev, __be32 remote, __be32 local)
 120 {
 121         unsigned int h0 = HASH(remote);
 122         unsigned int h1 = HASH(local);
 123         struct ip_tunnel *t;
 124         struct sit_net *sitn = net_generic(net, sit_net_id);
 125
 126         for_each_ip_tunnel_rcu(sitn->tunnels_r_l[h0 ^ h1]) {
 127                 if (local == t->parms.iph.saddr &&
 128                     remote == t->parms.iph.daddr &&
 129                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 130                     (t->dev->flags & IFF_UP))
 131                         return t;
 132         }
 133         for_each_ip_tunnel_rcu(sitn->tunnels_r[h0]) {
 134                 if (remote == t->parms.iph.daddr &&
 135                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 136                     (t->dev->flags & IFF_UP))
 137                         return t;
 138         }
 139         for_each_ip_tunnel_rcu(sitn->tunnels_l[h1]) {
 140                 if (local == t->parms.iph.saddr &&
 141                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 142                     (t->dev->flags & IFF_UP))
 143                         return t;
 144         }
 145         t = rcu_dereference(sitn->tunnels_wc[0]);
 146         if ((t != NULL) && (t->dev->flags & IFF_UP))
 147                 return t;
 148         return NULL;
 149 }
 150
 151 static struct ip_tunnel __rcu **__ipip6_bucket(struct sit_net *sitn,
 152                 struct ip_tunnel_parm *parms)
 153 {
 154         __be32 remote = parms->iph.daddr;
 155         __be32 local = parms->iph.saddr;
 156         unsigned int h = 0;
 157         int prio = 0;
 158
 159         if (remote) {
 160                 prio |= 2;
 161                 h ^= HASH(remote);
 162         }
 163         if (local) {
 164                 prio |= 1;
 165                 h ^= HASH(local);
 166         }
 167         return &sitn->tunnels[prio][h];
 168 }
 169
 170 static inline struct ip_tunnel __rcu **ipip6_bucket(struct sit_net *sitn,
 171                 struct ip_tunnel *t)
 172 {
 173         return __ipip6_bucket(sitn, &t->parms);
 174 }
 175
 176 static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
 177 {
 178         struct ip_tunnel __rcu **tp;
 179         struct ip_tunnel *iter;
 180
 181         for (tp = ipip6_bucket(sitn, t);
 182              (iter = rtnl_dereference(*tp)) != NULL;
 183              tp = &iter->next) {
 184                 if (t == iter) {
 185                         rcu_assign_pointer(*tp, t->next);
 186                         break;
 187                 }
 188         }
 189 }
 190
 191 static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
 192 {
 193         struct ip_tunnel __rcu **tp = ipip6_bucket(sitn, t);
 194
 195         rcu_assign_pointer(t->next, rtnl_dereference(*tp));
 196         rcu_assign_pointer(*tp, t);
 197 }
 198
 199 static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
 200 {
 201 #ifdef CONFIG_IPV6_SIT_6RD
 202         struct ip_tunnel *t = netdev_priv(dev);
 203
 204         if (t->dev == sitn->fb_tunnel_dev) {
 205                 ipv6_addr_set(&t->ip6rd.prefix, htonl(0x20020000), 0, 0, 0);
 206                 t->ip6rd.relay_prefix = 0;
 207                 t->ip6rd.prefixlen = 16;
 208                 t->ip6rd.relay_prefixlen = 0;
 209         } else {
 210                 struct ip_tunnel *t0 = netdev_priv(sitn->fb_tunnel_dev);
 211                 memcpy(&t->ip6rd, &t0->ip6rd, sizeof(t->ip6rd));
 212         }
 213 #endif
 214 }
 215
 216 static struct ip_tunnel *ipip6_tunnel_locate(struct net *net,
 217                 struct ip_tunnel_parm *parms, int create)
 218 {
 219         __be32 remote = parms->iph.daddr;
 220         __be32 local = parms->iph.saddr;
 221         struct ip_tunnel *t, *nt;
 222         struct ip_tunnel __rcu **tp;
 223         struct net_device *dev;
 224         char name[IFNAMSIZ];
 225         struct sit_net *sitn = net_generic(net, sit_net_id);
 226
 227         for (tp = __ipip6_bucket(sitn, parms);
 228             (t = rtnl_dereference(*tp)) != NULL;
 229              tp = &t->next) {
 230                 if (local == t->parms.iph.saddr &&
 231                     remote == t->parms.iph.daddr &&
 232                     parms->link == t->parms.link) {
 233                         if (create)
 234                                 return NULL;
 235                         else
 236                                 return t;
 237                 }
 238         }
 239         if (!create)
 240                 goto failed;
 241
 242         if (parms->name[0])
 243                 strlcpy(name, parms->name, IFNAMSIZ);
 244         else
 245                 strcpy(name, "sit%d");
 246
 247         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
 248         if (dev == NULL)
 249                 return NULL;
 250
 251         dev_net_set(dev, net);
 252
 253         if (strchr(name, '%')) {
 254                 if (dev_alloc_name(dev, name) < 0)
 255                         goto failed_free;
 256         }
 257
 258         nt = netdev_priv(dev);
 259
 260         nt->parms = *parms;
 261         if (ipip6_tunnel_init(dev) < 0)
 262                 goto failed_free;
 263         ipip6_tunnel_clone_6rd(dev, sitn);
 264
 265         if (parms->i_flags & SIT_ISATAP)
 266                 dev->priv_flags |= IFF_ISATAP;
 267
 268         if (register_netdevice(dev) < 0)
 269                 goto failed_free;
 270
 271         dev_hold(dev);
 272
 273         ipip6_tunnel_link(sitn, nt);
 274         return nt;
 275
 276 failed_free:
 277         ipip6_dev_free(dev);
 278 failed:
 279         return NULL;
 280 }
 281
 282 #define for_each_prl_rcu(start)                 \
 283         for (prl = rcu_dereference(start);      \
 284              prl;                               \
 285              prl = rcu_dereference(prl->next))
 286
 287 static struct ip_tunnel_prl_entry *
 288 __ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
 289 {
 290         struct ip_tunnel_prl_entry *prl;
 291
 292         for_each_prl_rcu(t->prl)
 293                 if (prl->addr == addr)
 294                         break;
 295         return prl;
 296
 297 }
 298
 299 static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
 300                                 struct ip_tunnel_prl __user *a)
 301 {
 302         struct ip_tunnel_prl kprl, *kp;
 303         struct ip_tunnel_prl_entry *prl;
 304         unsigned int cmax, c = 0, ca, len;
 305         int ret = 0;
 306
 307         if (copy_from_user(&kprl, a, sizeof(kprl)))
 308                 return -EFAULT;
 309         cmax = kprl.datalen / sizeof(kprl);
 310         if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
 311                 cmax = 1;
 312
 313         /* For simple GET or for root users,
 314          * we try harder to allocate.
 315          */
 316         kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
 317                 kcalloc(cmax, sizeof(*kp), GFP_KERNEL) :
 318                 NULL;
 319
 320         rcu_read_lock();
 321
 322         ca = t->prl_count < cmax ? t->prl_count : cmax;
 323
 324         if (!kp) {
 325                 /* We don't try hard to allocate much memory for
 326                  * non-root users.
 327                  * For root users, retry allocating enough memory for
 328                  * the answer.
 329                  */
 330                 kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC);
 331                 if (!kp) {
 332                         ret = -ENOMEM;
 333                         goto out;
 334                 }
 335         }
 336
 337         c = 0;
 338         for_each_prl_rcu(t->prl) {
 339                 if (c >= cmax)
 340                         break;
 341                 if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
 342                         continue;
 343                 kp[c].addr = prl->addr;
 344                 kp[c].flags = prl->flags;
 345                 c++;
 346                 if (kprl.addr != htonl(INADDR_ANY))
 347                         break;
 348         }
 349 out:
 350         rcu_read_unlock();
 351
 352         len = sizeof(*kp) * c;
 353         ret = 0;
 354         if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
 355                 ret = -EFAULT;
 356
 357         kfree(kp);
 358
 359         return ret;
 360 }
 361
 362 static int
 363 ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
 364 {
 365         struct ip_tunnel_prl_entry *p;
 366         int err = 0;
 367
 368         if (a->addr == htonl(INADDR_ANY))
 369                 return -EINVAL;
 370
 371         ASSERT_RTNL();
 372
 373         for (p = rtnl_dereference(t->prl); p; p = rtnl_dereference(p->next)) {
 374                 if (p->addr == a->addr) {
 375                         if (chg) {
 376                                 p->flags = a->flags;
 377                                 goto out;
 378                         }
 379                         err = -EEXIST;
 380                         goto out;
 381                 }
 382         }
 383
 384         if (chg) {
 385                 err = -ENXIO;
 386                 goto out;
 387         }
 388
 389         p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
 390         if (!p) {
 391                 err = -ENOBUFS;
 392                 goto out;
 393         }
 394
 395         p->next = t->prl;
 396         p->addr = a->addr;
 397         p->flags = a->flags;
 398         t->prl_count++;
 399         rcu_assign_pointer(t->prl, p);
 400 out:
 401         return err;
 402 }
 403
 404 static void prl_entry_destroy_rcu(struct rcu_head *head)
 405 {
 406         kfree(container_of(head, struct ip_tunnel_prl_entry, rcu_head));
 407 }
 408
 409 static void prl_list_destroy_rcu(struct rcu_head *head)
 410 {
 411         struct ip_tunnel_prl_entry *p, *n;
 412
 413         p = container_of(head, struct ip_tunnel_prl_entry, rcu_head);
 414         do {
 415                 n = p->next;
 416                 kfree(p);
 417                 p = n;
 418         } while (p);
 419 }
 420
 421 static int
 422 ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
 423 {
 424         struct ip_tunnel_prl_entry *x, **p;
 425         int err = 0;
 426
 427         ASSERT_RTNL();
 428
 429         if (a && a->addr != htonl(INADDR_ANY)) {
 430                 for (p = &t->prl; *p; p = &(*p)->next) {
 431                         if ((*p)->addr == a->addr) {
 432                                 x = *p;
 433                                 *p = x->next;
 434                                 call_rcu(&x->rcu_head, prl_entry_destroy_rcu);
 435                                 t->prl_count--;
 436                                 goto out;
 437                         }
 438                 }
 439                 err = -ENXIO;
 440         } else {
 441                 if (t->prl) {
 442                         t->prl_count = 0;
 443                         x = t->prl;
 444                         call_rcu(&x->rcu_head, prl_list_destroy_rcu);
 445                         t->prl = NULL;
 446                 }
 447         }
 448 out:
 449         return err;
 450 }
 451
 452 static int
 453 isatap_chksrc(struct sk_buff *skb, struct iphdr *iph, struct ip_tunnel *t)
 454 {
 455         struct ip_tunnel_prl_entry *p;
 456         int ok = 1;
 457
 458         rcu_read_lock();
 459         p = __ipip6_tunnel_locate_prl(t, iph->saddr);
 460         if (p) {
 461                 if (p->flags & PRL_DEFAULT)
 462                         skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
 463                 else
 464                         skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
 465         } else {
 466                 struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
 467                 if (ipv6_addr_is_isatap(addr6) &&
 468                     (addr6->s6_addr32[3] == iph->saddr) &&
 469                     ipv6_chk_prefix(addr6, t->dev))
 470                         skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
 471                 else
 472                         ok = 0;
 473         }
 474         rcu_read_unlock();
 475         return ok;
 476 }
 477
 478 static void ipip6_tunnel_uninit(struct net_device *dev)
 479 {
 480         struct net *net = dev_net(dev);
 481         struct sit_net *sitn = net_generic(net, sit_net_id);
 482
 483         if (dev == sitn->fb_tunnel_dev) {
 484                 rcu_assign_pointer(sitn->tunnels_wc[0], NULL);
 485         } else {
 486                 ipip6_tunnel_unlink(sitn, netdev_priv(dev));
 487                 ipip6_tunnel_del_prl(netdev_priv(dev), NULL);
 488         }
 489         dev_put(dev);
 490 }
 491
 492
 493 static int ipip6_err(struct sk_buff *skb, u32 info)
 494 {
 495
 496 /* All the routers (except for Linux) return only
 497    8 bytes of packet payload. It means, that precise relaying of
 498    ICMP in the real Internet is absolutely infeasible.
 499  */
 500         struct iphdr *iph = (struct iphdr*)skb->data;
 501         const int type = icmp_hdr(skb)->type;
 502         const int code = icmp_hdr(skb)->code;
 503         struct ip_tunnel *t;
 504         int err;
 505
 506         switch (type) {
 507         default:
 508         case ICMP_PARAMETERPROB:
 509                 return 0;
 510
 511         case ICMP_DEST_UNREACH:
 512                 switch (code) {
 513                 case ICMP_SR_FAILED:
 514                 case ICMP_PORT_UNREACH:
 515                         /* Impossible event. */
 516                         return 0;
 517                 case ICMP_FRAG_NEEDED:
 518                         /* Soft state for pmtu is maintained by IP core. */
 519                         return 0;
 520                 default:
 521                         /* All others are translated to HOST_UNREACH.
 522                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 523                            I believe they are just ether pollution. --ANK
 524                          */
 525                         break;
 526                 }
 527                 break;
 528         case ICMP_TIME_EXCEEDED:
 529                 if (code != ICMP_EXC_TTL)
 530                         return 0;
 531                 break;
 532         }
 533
 534         err = -ENOENT;
 535
 536         rcu_read_lock();
 537         t = ipip6_tunnel_lookup(dev_net(skb->dev),
 538                                 skb->dev,
 539                                 iph->daddr,
 540                                 iph->saddr);
 541         if (t == NULL || t->parms.iph.daddr == 0)
 542                 goto out;
 543
 544         err = 0;
 545         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 546                 goto out;
 547
 548         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
 549                 t->err_count++;
 550         else
 551                 t->err_count = 1;
 552         t->err_time = jiffies;
 553 out:
 554         rcu_read_unlock();
 555         return err;
 556 }
 557
 558 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 559 {
 560         if (INET_ECN_is_ce(iph->tos))
 561                 IP6_ECN_set_ce(ipv6_hdr(skb));
 562 }
 563
 564 static int ipip6_rcv(struct sk_buff *skb)
 565 {
 566         struct iphdr *iph;
 567         struct ip_tunnel *tunnel;
 568
 569         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 570                 goto out;
 571
 572         iph = ip_hdr(skb);
 573
 574         rcu_read_lock();
 575         tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
 576                                      iph->saddr, iph->daddr);
 577         if (tunnel != NULL) {
 578                 struct pcpu_tstats *tstats;
 579
 580                 secpath_reset(skb);
 581                 skb->mac_header = skb->network_header;
 582                 skb_reset_network_header(skb);
 583                 IPCB(skb)->flags = 0;
 584                 skb->protocol = htons(ETH_P_IPV6);
 585                 skb->pkt_type = PACKET_HOST;
 586
 587                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
 588                     !isatap_chksrc(skb, iph, tunnel)) {
 589                         tunnel->dev->stats.rx_errors++;
 590                         rcu_read_unlock();
 591                         kfree_skb(skb);
 592                         return 0;
 593                 }
 594
 595                 tstats = this_cpu_ptr(tunnel->dev->tstats);
 596                 tstats->rx_packets++;
 597                 tstats->rx_bytes += skb->len;
 598
 599                 __skb_tunnel_rx(skb, tunnel->dev);
 600
 601                 ipip6_ecn_decapsulate(iph, skb);
 602
 603                 netif_rx(skb);
 604
 605                 rcu_read_unlock();
 606                 return 0;
 607         }
 608
 609         /* no tunnel matched,  let upstream know, ipsec may handle it */
 610         rcu_read_unlock();
 611         return 1;
 612 out:
 613         kfree_skb(skb);
 614         return 0;
 615 }
 616
 617 /*
 618  * Returns the embedded IPv4 address if the IPv6 address
 619  * comes from 6rd / 6to4 (RFC 3056) addr space.
 620  */
 621 static inline
 622 __be32 try_6rd(struct in6_addr *v6dst, struct ip_tunnel *tunnel)
 623 {
 624         __be32 dst = 0;
 625
 626 #ifdef CONFIG_IPV6_SIT_6RD
 627         if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
 628                               tunnel->ip6rd.prefixlen)) {
 629                 unsigned int pbw0, pbi0;
 630                 int pbi1;
 631                 u32 d;
 632
 633                 pbw0 = tunnel->ip6rd.prefixlen >> 5;
 634                 pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
 635
 636                 d = (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
 637                     tunnel->ip6rd.relay_prefixlen;
 638
 639                 pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
 640                 if (pbi1 > 0)
 641                         d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
 642                              (32 - pbi1);
 643
 644                 dst = tunnel->ip6rd.relay_prefix | htonl(d);
 645         }
 646 #else
 647         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 648                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 649                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 650         }
 651 #endif
 652         return dst;
 653 }
 654
 655 /*
 656  *      This function assumes it is being called from dev_queue_xmit()
 657  *      and that skb is filled properly by that function.
 658  */
 659
 660 static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 661                                      struct net_device *dev)
 662 {
 663         struct ip_tunnel *tunnel = netdev_priv(dev);
 664         struct pcpu_tstats *tstats;
 665         struct iphdr  *tiph = &tunnel->parms.iph;
 666         struct ipv6hdr *iph6 = ipv6_hdr(skb);
 667         u8     tos = tunnel->parms.iph.tos;
 668         __be16 df = tiph->frag_off;
 669         struct rtable *rt;                      /* Route to the other host */
 670         struct net_device *tdev;                /* Device to other host */
 671         struct iphdr  *iph;                     /* Our new IP header */
 672         unsigned int max_headroom;              /* The extra header space needed */
 673         __be32 dst = tiph->daddr;
 674         int    mtu;
 675         struct in6_addr *addr6;
 676         int addr_type;
 677
 678         if (skb->protocol != htons(ETH_P_IPV6))
 679                 goto tx_error;
 680
 681         /* ISATAP (RFC4214) - must come before 6to4 */
 682         if (dev->priv_flags & IFF_ISATAP) {
 683                 struct neighbour *neigh = NULL;
 684
 685                 if (skb_dst(skb))
 686                         neigh = skb_dst(skb)->neighbour;
 687
 688                 if (neigh == NULL) {
 689                         if (net_ratelimit())
 690                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 691                         goto tx_error;
 692                 }
 693
 694                 addr6 = (struct in6_addr*)&neigh->primary_key;
 695                 addr_type = ipv6_addr_type(addr6);
 696
 697                 if ((addr_type & IPV6_ADDR_UNICAST) &&
 698                      ipv6_addr_is_isatap(addr6))
 699                         dst = addr6->s6_addr32[3];
 700                 else
 701                         goto tx_error;
 702         }
 703
 704         if (!dst)
 705                 dst = try_6rd(&iph6->daddr, tunnel);
 706
 707         if (!dst) {
 708                 struct neighbour *neigh = NULL;
 709
 710                 if (skb_dst(skb))
 711                         neigh = skb_dst(skb)->neighbour;
 712
 713                 if (neigh == NULL) {
 714                         if (net_ratelimit())
 715                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 716                         goto tx_error;
 717                 }
 718
 719                 addr6 = (struct in6_addr*)&neigh->primary_key;
 720                 addr_type = ipv6_addr_type(addr6);
 721
 722                 if (addr_type == IPV6_ADDR_ANY) {
 723                         addr6 = &ipv6_hdr(skb)->daddr;
 724                         addr_type = ipv6_addr_type(addr6);
 725                 }
 726
 727                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 728                         goto tx_error_icmp;
 729
 730                 dst = addr6->s6_addr32[3];
 731         }
 732
 733         {
 734                 struct flowi fl = { .nl_u = { .ip4_u =
 735                                               { .daddr = dst,
 736                                                 .saddr = tiph->saddr,
 737                                                 .tos = RT_TOS(tos) } },
 738                                     .oif = tunnel->parms.link,
 739                                     .proto = IPPROTO_IPV6 };
 740                 if (ip_route_output_key(dev_net(dev), &rt, &fl)) {
 741                         dev->stats.tx_carrier_errors++;
 742                         goto tx_error_icmp;
 743                 }
 744         }
 745         if (rt->rt_type != RTN_UNICAST) {
 746                 ip_rt_put(rt);
 747                 dev->stats.tx_carrier_errors++;
 748                 goto tx_error_icmp;
 749         }
 750         tdev = rt->dst.dev;
 751
 752         if (tdev == dev) {
 753                 ip_rt_put(rt);
 754                 dev->stats.collisions++;
 755                 goto tx_error;
 756         }
 757
 758         if (df) {
 759                 mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
 760
 761                 if (mtu < 68) {
 762                         dev->stats.collisions++;
 763                         ip_rt_put(rt);
 764                         goto tx_error;
 765                 }
 766
 767                 if (mtu < IPV6_MIN_MTU) {
 768                         mtu = IPV6_MIN_MTU;
 769                         df = 0;
 770                 }
 771
 772                 if (tunnel->parms.iph.daddr && skb_dst(skb))
 773                         skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 774
 775                 if (skb->len > mtu) {
 776                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
 777                         ip_rt_put(rt);
 778                         goto tx_error;
 779                 }
 780         }
 781
 782         if (tunnel->err_count > 0) {
 783                 if (time_before(jiffies,
 784                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
 785                         tunnel->err_count--;
 786                         dst_link_failure(skb);
 787                 } else
 788                         tunnel->err_count = 0;
 789         }
 790
 791         /*
 792          * Okay, now see if we can stuff it in the buffer as-is.
 793          */
 794         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 795
 796         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 797             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 798                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 799                 if (!new_skb) {
 800                         ip_rt_put(rt);
 801                         dev->stats.tx_dropped++;
 802                         dev_kfree_skb(skb);
 803                         return NETDEV_TX_OK;
 804                 }
 805                 if (skb->sk)
 806                         skb_set_owner_w(new_skb, skb->sk);
 807                 dev_kfree_skb(skb);
 808                 skb = new_skb;
 809                 iph6 = ipv6_hdr(skb);
 810         }
 811
 812         skb->transport_header = skb->network_header;
 813         skb_push(skb, sizeof(struct iphdr));
 814         skb_reset_network_header(skb);
 815         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 816         IPCB(skb)->flags = 0;
 817         skb_dst_drop(skb);
 818         skb_dst_set(skb, &rt->dst);
 819
 820         /*
 821          *      Push down and install the IPIP header.
 822          */
 823
 824         iph                     =       ip_hdr(skb);
 825         iph->version            =       4;
 826         iph->ihl                =       sizeof(struct iphdr)>>2;
 827         iph->frag_off           =       df;
 828         iph->protocol           =       IPPROTO_IPV6;
 829         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 830         iph->daddr              =       rt->rt_dst;
 831         iph->saddr              =       rt->rt_src;
 832
 833         if ((iph->ttl = tiph->ttl) == 0)
 834                 iph->ttl        =       iph6->hop_limit;
 835
 836         nf_reset(skb);
 837         tstats = this_cpu_ptr(dev->tstats);
 838         __IPTUNNEL_XMIT(tstats, &dev->stats);
 839         return NETDEV_TX_OK;
 840
 841 tx_error_icmp:
 842         dst_link_failure(skb);
 843 tx_error:
 844         dev->stats.tx_errors++;
 845         dev_kfree_skb(skb);
 846         return NETDEV_TX_OK;
 847 }
 848
 849 static void ipip6_tunnel_bind_dev(struct net_device *dev)
 850 {
 851         struct net_device *tdev = NULL;
 852         struct ip_tunnel *tunnel;
 853         struct iphdr *iph;
 854
 855         tunnel = netdev_priv(dev);
 856         iph = &tunnel->parms.iph;
 857
 858         if (iph->daddr) {
 859                 struct flowi fl = { .nl_u = { .ip4_u =
 860                                               { .daddr = iph->daddr,
 861                                                 .saddr = iph->saddr,
 862                                                 .tos = RT_TOS(iph->tos) } },
 863                                     .oif = tunnel->parms.link,
 864                                     .proto = IPPROTO_IPV6 };
 865                 struct rtable *rt;
 866                 if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 867                         tdev = rt->dst.dev;
 868                         ip_rt_put(rt);
 869                 }
 870                 dev->flags |= IFF_POINTOPOINT;
 871         }
 872
 873         if (!tdev && tunnel->parms.link)
 874                 tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);
 875
 876         if (tdev) {
 877                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 878                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 879                 if (dev->mtu < IPV6_MIN_MTU)
 880                         dev->mtu = IPV6_MIN_MTU;
 881         }
 882         dev->iflink = tunnel->parms.link;
 883 }
 884
 885 static int
 886 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 887 {
 888         int err = 0;
 889         struct ip_tunnel_parm p;
 890         struct ip_tunnel_prl prl;
 891         struct ip_tunnel *t;
 892         struct net *net = dev_net(dev);
 893         struct sit_net *sitn = net_generic(net, sit_net_id);
 894 #ifdef CONFIG_IPV6_SIT_6RD
 895         struct ip_tunnel_6rd ip6rd;
 896 #endif
 897
 898         switch (cmd) {
 899         case SIOCGETTUNNEL:
 900 #ifdef CONFIG_IPV6_SIT_6RD
 901         case SIOCGET6RD:
 902 #endif
 903                 t = NULL;
 904                 if (dev == sitn->fb_tunnel_dev) {
 905                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 906                                 err = -EFAULT;
 907                                 break;
 908                         }
 909                         t = ipip6_tunnel_locate(net, &p, 0);
 910                 }
 911                 if (t == NULL)
 912                         t = netdev_priv(dev);
 913
 914                 err = -EFAULT;
 915                 if (cmd == SIOCGETTUNNEL) {
 916                         memcpy(&p, &t->parms, sizeof(p));
 917                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p,
 918                                          sizeof(p)))
 919                                 goto done;
 920 #ifdef CONFIG_IPV6_SIT_6RD
 921                 } else {
 922                         ipv6_addr_copy(&ip6rd.prefix, &t->ip6rd.prefix);
 923                         ip6rd.relay_prefix = t->ip6rd.relay_prefix;
 924                         ip6rd.prefixlen = t->ip6rd.prefixlen;
 925                         ip6rd.relay_prefixlen = t->ip6rd.relay_prefixlen;
 926                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &ip6rd,
 927                                          sizeof(ip6rd)))
 928                                 goto done;
 929 #endif
 930                 }
 931                 err = 0;
 932                 break;
 933
 934         case SIOCADDTUNNEL:
 935         case SIOCCHGTUNNEL:
 936                 err = -EPERM;
 937                 if (!capable(CAP_NET_ADMIN))
 938                         goto done;
 939
 940                 err = -EFAULT;
 941                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 942                         goto done;
 943
 944                 err = -EINVAL;
 945                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 946                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 947                         goto done;
 948                 if (p.iph.ttl)
 949                         p.iph.frag_off |= htons(IP_DF);
 950
 951                 t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
 952
 953                 if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 954                         if (t != NULL) {
 955                                 if (t->dev != dev) {
 956                                         err = -EEXIST;
 957                                         break;
 958                                 }
 959                         } else {
 960                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 961                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 962                                         err = -EINVAL;
 963                                         break;
 964                                 }
 965                                 t = netdev_priv(dev);
 966                                 ipip6_tunnel_unlink(sitn, t);
 967                                 synchronize_net();
 968                                 t->parms.iph.saddr = p.iph.saddr;
 969                                 t->parms.iph.daddr = p.iph.daddr;
 970                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 971                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 972                                 ipip6_tunnel_link(sitn, t);
 973                                 netdev_state_change(dev);
 974                         }
 975                 }
 976
 977                 if (t) {
 978                         err = 0;
 979                         if (cmd == SIOCCHGTUNNEL) {
 980                                 t->parms.iph.ttl = p.iph.ttl;
 981                                 t->parms.iph.tos = p.iph.tos;
 982                                 if (t->parms.link != p.link) {
 983                                         t->parms.link = p.link;
 984                                         ipip6_tunnel_bind_dev(dev);
 985                                         netdev_state_change(dev);
 986                                 }
 987                         }
 988                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 989                                 err = -EFAULT;
 990                 } else
 991                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 992                 break;
 993
 994         case SIOCDELTUNNEL:
 995                 err = -EPERM;
 996                 if (!capable(CAP_NET_ADMIN))
 997                         goto done;
 998
 999                 if (dev == sitn->fb_tunnel_dev) {
1000                         err = -EFAULT;
1001                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
1002                                 goto done;
1003                         err = -ENOENT;
1004                         if ((t = ipip6_tunnel_locate(net, &p, 0)) == NULL)
1005                                 goto done;
1006                         err = -EPERM;
1007                         if (t == netdev_priv(sitn->fb_tunnel_dev))
1008                                 goto done;
1009                         dev = t->dev;
1010                 }
1011                 unregister_netdevice(dev);
1012                 err = 0;
1013                 break;
1014
1015         case SIOCGETPRL:
1016                 err = -EINVAL;
1017                 if (dev == sitn->fb_tunnel_dev)
1018                         goto done;
1019                 err = -ENOENT;
1020                 if (!(t = netdev_priv(dev)))
1021                         goto done;
1022                 err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
1023                 break;
1024
1025         case SIOCADDPRL:
1026         case SIOCDELPRL:
1027         case SIOCCHGPRL:
1028                 err = -EPERM;
1029                 if (!capable(CAP_NET_ADMIN))
1030                         goto done;
1031                 err = -EINVAL;
1032                 if (dev == sitn->fb_tunnel_dev)
1033                         goto done;
1034                 err = -EFAULT;
1035                 if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
1036                         goto done;
1037                 err = -ENOENT;
1038                 if (!(t = netdev_priv(dev)))
1039                         goto done;
1040
1041                 switch (cmd) {
1042                 case SIOCDELPRL:
1043                         err = ipip6_tunnel_del_prl(t, &prl);
1044                         break;
1045                 case SIOCADDPRL:
1046                 case SIOCCHGPRL:
1047                         err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
1048                         break;
1049                 }
1050                 netdev_state_change(dev);
1051                 break;
1052
1053 #ifdef CONFIG_IPV6_SIT_6RD
1054         case SIOCADD6RD:
1055         case SIOCCHG6RD:
1056         case SIOCDEL6RD:
1057                 err = -EPERM;
1058                 if (!capable(CAP_NET_ADMIN))
1059                         goto done;
1060
1061                 err = -EFAULT;
1062                 if (copy_from_user(&ip6rd, ifr->ifr_ifru.ifru_data,
1063                                    sizeof(ip6rd)))
1064                         goto done;
1065
1066                 t = netdev_priv(dev);
1067
1068                 if (cmd != SIOCDEL6RD) {
1069                         struct in6_addr prefix;
1070                         __be32 relay_prefix;
1071
1072                         err = -EINVAL;
1073                         if (ip6rd.relay_prefixlen > 32 ||
1074                             ip6rd.prefixlen + (32 - ip6rd.relay_prefixlen) > 64)
1075                                 goto done;
1076
1077                         ipv6_addr_prefix(&prefix, &ip6rd.prefix,
1078                                          ip6rd.prefixlen);
1079                         if (!ipv6_addr_equal(&prefix, &ip6rd.prefix))
1080                                 goto done;
1081                         if (ip6rd.relay_prefixlen)
1082                                 relay_prefix = ip6rd.relay_prefix &
1083                                                htonl(0xffffffffUL <<
1084                                                      (32 - ip6rd.relay_prefixlen));
1085                         else
1086                                 relay_prefix = 0;
1087                         if (relay_prefix != ip6rd.relay_prefix)
1088                                 goto done;
1089
1090                         ipv6_addr_copy(&t->ip6rd.prefix, &prefix);
1091                         t->ip6rd.relay_prefix = relay_prefix;
1092                         t->ip6rd.prefixlen = ip6rd.prefixlen;
1093                         t->ip6rd.relay_prefixlen = ip6rd.relay_prefixlen;
1094                 } else
1095                         ipip6_tunnel_clone_6rd(dev, sitn);
1096
1097                 err = 0;
1098                 break;
1099 #endif
1100
1101         default:
1102                 err = -EINVAL;
1103         }
1104
1105 done:
1106         return err;
1107 }
1108
1109 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1110 {
1111         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
1112                 return -EINVAL;
1113         dev->mtu = new_mtu;
1114         return 0;
1115 }
1116
1117 static const struct net_device_ops ipip6_netdev_ops = {
1118         .ndo_uninit     = ipip6_tunnel_uninit,
1119         .ndo_start_xmit = ipip6_tunnel_xmit,
1120         .ndo_do_ioctl   = ipip6_tunnel_ioctl,
1121         .ndo_change_mtu = ipip6_tunnel_change_mtu,
1122         .ndo_get_stats  = ipip6_get_stats,
1123 };
1124
1125 static void ipip6_dev_free(struct net_device *dev)
1126 {
1127         free_percpu(dev->tstats);
1128         free_netdev(dev);
1129 }
1130
1131 static void ipip6_tunnel_setup(struct net_device *dev)
1132 {
1133         dev->netdev_ops         = &ipip6_netdev_ops;
1134         dev->destructor         = ipip6_dev_free;
1135
1136         dev->type               = ARPHRD_SIT;
1137         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
1138         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
1139         dev->flags              = IFF_NOARP;
1140         dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
1141         dev->iflink             = 0;
1142         dev->addr_len           = 4;
1143         dev->features           |= NETIF_F_NETNS_LOCAL;
1144         dev->features           |= NETIF_F_LLTX;
1145 }
1146
1147 static int ipip6_tunnel_init(struct net_device *dev)
1148 {
1149         struct ip_tunnel *tunnel = netdev_priv(dev);
1150
1151         tunnel->dev = dev;
1152         strcpy(tunnel->parms.name, dev->name);
1153
1154         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1155         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1156
1157         ipip6_tunnel_bind_dev(dev);
1158         dev->tstats = alloc_percpu(struct pcpu_tstats);
1159         if (!dev->tstats)
1160                 return -ENOMEM;
1161
1162         return 0;
1163 }
1164
1165 static int __net_init ipip6_fb_tunnel_init(struct net_device *dev)
1166 {
1167         struct ip_tunnel *tunnel = netdev_priv(dev);
1168         struct iphdr *iph = &tunnel->parms.iph;
1169         struct net *net = dev_net(dev);
1170         struct sit_net *sitn = net_generic(net, sit_net_id);
1171
1172         tunnel->dev = dev;
1173         strcpy(tunnel->parms.name, dev->name);
1174
1175         iph->version            = 4;
1176         iph->protocol           = IPPROTO_IPV6;
1177         iph->ihl                = 5;
1178         iph->ttl                = 64;
1179
1180         dev->tstats = alloc_percpu(struct pcpu_tstats);
1181         if (!dev->tstats)
1182                 return -ENOMEM;
1183         dev_hold(dev);
1184         sitn->tunnels_wc[0]     = tunnel;
1185         return 0;
1186 }
1187
1188 static struct xfrm_tunnel sit_handler __read_mostly = {
1189         .handler        =       ipip6_rcv,
1190         .err_handler    =       ipip6_err,
1191         .priority       =       1,
1192 };
1193
1194 static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_head *head)
1195 {
1196         int prio;
1197
1198         for (prio = 1; prio < 4; prio++) {
1199                 int h;
1200                 for (h = 0; h < HASH_SIZE; h++) {
1201                         struct ip_tunnel *t = sitn->tunnels[prio][h];
1202
1203                         while (t != NULL) {
1204                                 unregister_netdevice_queue(t->dev, head);
1205                                 t = t->next;
1206                         }
1207                 }
1208         }
1209 }
1210
1211 static int __net_init sit_init_net(struct net *net)
1212 {
1213         struct sit_net *sitn = net_generic(net, sit_net_id);
1214         int err;
1215
1216         sitn->tunnels[0] = sitn->tunnels_wc;
1217         sitn->tunnels[1] = sitn->tunnels_l;
1218         sitn->tunnels[2] = sitn->tunnels_r;
1219         sitn->tunnels[3] = sitn->tunnels_r_l;
1220
1221         sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
1222                                            ipip6_tunnel_setup);
1223         if (!sitn->fb_tunnel_dev) {
1224                 err = -ENOMEM;
1225                 goto err_alloc_dev;
1226         }
1227         dev_net_set(sitn->fb_tunnel_dev, net);
1228
1229         err = ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
1230         if (err)
1231                 goto err_dev_free;
1232
1233         ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
1234
1235         if ((err = register_netdev(sitn->fb_tunnel_dev)))
1236                 goto err_reg_dev;
1237
1238         return 0;
1239
1240 err_reg_dev:
1241         dev_put(sitn->fb_tunnel_dev);
1242 err_dev_free:
1243         ipip6_dev_free(sitn->fb_tunnel_dev);
1244 err_alloc_dev:
1245         return err;
1246 }
1247
1248 static void __net_exit sit_exit_net(struct net *net)
1249 {
1250         struct sit_net *sitn = net_generic(net, sit_net_id);
1251         LIST_HEAD(list);
1252
1253         rtnl_lock();
1254         sit_destroy_tunnels(sitn, &list);
1255         unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);
1256         unregister_netdevice_many(&list);
1257         rtnl_unlock();
1258 }
1259
1260 static struct pernet_operations sit_net_ops = {
1261         .init = sit_init_net,
1262         .exit = sit_exit_net,
1263         .id   = &sit_net_id,
1264         .size = sizeof(struct sit_net),
1265 };
1266
1267 static void __exit sit_cleanup(void)
1268 {
1269         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1270
1271         unregister_pernet_device(&sit_net_ops);
1272         rcu_barrier(); /* Wait for completion of call_rcu()'s */
1273 }
1274
1275 static int __init sit_init(void)
1276 {
1277         int err;
1278
1279         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
1280
1281         err = register_pernet_device(&sit_net_ops);
1282         if (err < 0)
1283                 return err;
1284         err = xfrm4_tunnel_register(&sit_handler, AF_INET6);
1285         if (err < 0) {
1286                 unregister_pernet_device(&sit_net_ops);
1287                 printk(KERN_INFO "sit init: Can't add protocol\n");
1288         }
1289         return err;
1290 }
1291
1292 module_init(sit_init);
1293 module_exit(sit_cleanup);
1294 MODULE_LICENSE("GPL");
1295 MODULE_ALIAS("sit0");