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_INIT_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_INIT_POINTER(t->next, rtnl_dereference(*tp));
 196         RCU_INIT_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         nt = netdev_priv(dev);
 254
 255         nt->parms = *parms;
 256         if (ipip6_tunnel_init(dev) < 0)
 257                 goto failed_free;
 258         ipip6_tunnel_clone_6rd(dev, sitn);
 259
 260         if (parms->i_flags & SIT_ISATAP)
 261                 dev->priv_flags |= IFF_ISATAP;
 262
 263         if (register_netdevice(dev) < 0)
 264                 goto failed_free;
 265
 266         strcpy(nt->parms.name, dev->name);
 267
 268         dev_hold(dev);
 269
 270         ipip6_tunnel_link(sitn, nt);
 271         return nt;
 272
 273 failed_free:
 274         ipip6_dev_free(dev);
 275 failed:
 276         return NULL;
 277 }
 278
 279 #define for_each_prl_rcu(start)                 \
 280         for (prl = rcu_dereference(start);      \
 281              prl;                               \
 282              prl = rcu_dereference(prl->next))
 283
 284 static struct ip_tunnel_prl_entry *
 285 __ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
 286 {
 287         struct ip_tunnel_prl_entry *prl;
 288
 289         for_each_prl_rcu(t->prl)
 290                 if (prl->addr == addr)
 291                         break;
 292         return prl;
 293
 294 }
 295
 296 static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
 297                                 struct ip_tunnel_prl __user *a)
 298 {
 299         struct ip_tunnel_prl kprl, *kp;
 300         struct ip_tunnel_prl_entry *prl;
 301         unsigned int cmax, c = 0, ca, len;
 302         int ret = 0;
 303
 304         if (copy_from_user(&kprl, a, sizeof(kprl)))
 305                 return -EFAULT;
 306         cmax = kprl.datalen / sizeof(kprl);
 307         if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
 308                 cmax = 1;
 309
 310         /* For simple GET or for root users,
 311          * we try harder to allocate.
 312          */
 313         kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
 314                 kcalloc(cmax, sizeof(*kp), GFP_KERNEL) :
 315                 NULL;
 316
 317         rcu_read_lock();
 318
 319         ca = t->prl_count < cmax ? t->prl_count : cmax;
 320
 321         if (!kp) {
 322                 /* We don't try hard to allocate much memory for
 323                  * non-root users.
 324                  * For root users, retry allocating enough memory for
 325                  * the answer.
 326                  */
 327                 kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC);
 328                 if (!kp) {
 329                         ret = -ENOMEM;
 330                         goto out;
 331                 }
 332         }
 333
 334         c = 0;
 335         for_each_prl_rcu(t->prl) {
 336                 if (c >= cmax)
 337                         break;
 338                 if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
 339                         continue;
 340                 kp[c].addr = prl->addr;
 341                 kp[c].flags = prl->flags;
 342                 c++;
 343                 if (kprl.addr != htonl(INADDR_ANY))
 344                         break;
 345         }
 346 out:
 347         rcu_read_unlock();
 348
 349         len = sizeof(*kp) * c;
 350         ret = 0;
 351         if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
 352                 ret = -EFAULT;
 353
 354         kfree(kp);
 355
 356         return ret;
 357 }
 358
 359 static int
 360 ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
 361 {
 362         struct ip_tunnel_prl_entry *p;
 363         int err = 0;
 364
 365         if (a->addr == htonl(INADDR_ANY))
 366                 return -EINVAL;
 367
 368         ASSERT_RTNL();
 369
 370         for (p = rtnl_dereference(t->prl); p; p = rtnl_dereference(p->next)) {
 371                 if (p->addr == a->addr) {
 372                         if (chg) {
 373                                 p->flags = a->flags;
 374                                 goto out;
 375                         }
 376                         err = -EEXIST;
 377                         goto out;
 378                 }
 379         }
 380
 381         if (chg) {
 382                 err = -ENXIO;
 383                 goto out;
 384         }
 385
 386         p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
 387         if (!p) {
 388                 err = -ENOBUFS;
 389                 goto out;
 390         }
 391
 392         p->next = t->prl;
 393         p->addr = a->addr;
 394         p->flags = a->flags;
 395         t->prl_count++;
 396         RCU_INIT_POINTER(t->prl, p);
 397 out:
 398         return err;
 399 }
 400
 401 static void prl_list_destroy_rcu(struct rcu_head *head)
 402 {
 403         struct ip_tunnel_prl_entry *p, *n;
 404
 405         p = container_of(head, struct ip_tunnel_prl_entry, rcu_head);
 406         do {
 407                 n = rcu_dereference_protected(p->next, 1);
 408                 kfree(p);
 409                 p = n;
 410         } while (p);
 411 }
 412
 413 static int
 414 ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
 415 {
 416         struct ip_tunnel_prl_entry *x;
 417         struct ip_tunnel_prl_entry __rcu **p;
 418         int err = 0;
 419
 420         ASSERT_RTNL();
 421
 422         if (a && a->addr != htonl(INADDR_ANY)) {
 423                 for (p = &t->prl;
 424                      (x = rtnl_dereference(*p)) != NULL;
 425                      p = &x->next) {
 426                         if (x->addr == a->addr) {
 427                                 *p = x->next;
 428                                 kfree_rcu(x, rcu_head);
 429                                 t->prl_count--;
 430                                 goto out;
 431                         }
 432                 }
 433                 err = -ENXIO;
 434         } else {
 435                 x = rtnl_dereference(t->prl);
 436                 if (x) {
 437                         t->prl_count = 0;
 438                         call_rcu(&x->rcu_head, prl_list_destroy_rcu);
 439                         t->prl = NULL;
 440                 }
 441         }
 442 out:
 443         return err;
 444 }
 445
 446 static int
 447 isatap_chksrc(struct sk_buff *skb, const struct iphdr *iph, struct ip_tunnel *t)
 448 {
 449         struct ip_tunnel_prl_entry *p;
 450         int ok = 1;
 451
 452         rcu_read_lock();
 453         p = __ipip6_tunnel_locate_prl(t, iph->saddr);
 454         if (p) {
 455                 if (p->flags & PRL_DEFAULT)
 456                         skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
 457                 else
 458                         skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
 459         } else {
 460                 const struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
 461
 462                 if (ipv6_addr_is_isatap(addr6) &&
 463                     (addr6->s6_addr32[3] == iph->saddr) &&
 464                     ipv6_chk_prefix(addr6, t->dev))
 465                         skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
 466                 else
 467                         ok = 0;
 468         }
 469         rcu_read_unlock();
 470         return ok;
 471 }
 472
 473 static void ipip6_tunnel_uninit(struct net_device *dev)
 474 {
 475         struct net *net = dev_net(dev);
 476         struct sit_net *sitn = net_generic(net, sit_net_id);
 477
 478         if (dev == sitn->fb_tunnel_dev) {
 479                 RCU_INIT_POINTER(sitn->tunnels_wc[0], NULL);
 480         } else {
 481                 ipip6_tunnel_unlink(sitn, netdev_priv(dev));
 482                 ipip6_tunnel_del_prl(netdev_priv(dev), NULL);
 483         }
 484         dev_put(dev);
 485 }
 486
 487
 488 static int ipip6_err(struct sk_buff *skb, u32 info)
 489 {
 490
 491 /* All the routers (except for Linux) return only
 492    8 bytes of packet payload. It means, that precise relaying of
 493    ICMP in the real Internet is absolutely infeasible.
 494  */
 495         const struct iphdr *iph = (const struct iphdr *)skb->data;
 496         const int type = icmp_hdr(skb)->type;
 497         const int code = icmp_hdr(skb)->code;
 498         struct ip_tunnel *t;
 499         int err;
 500
 501         switch (type) {
 502         default:
 503         case ICMP_PARAMETERPROB:
 504                 return 0;
 505
 506         case ICMP_DEST_UNREACH:
 507                 switch (code) {
 508                 case ICMP_SR_FAILED:
 509                 case ICMP_PORT_UNREACH:
 510                         /* Impossible event. */
 511                         return 0;
 512                 case ICMP_FRAG_NEEDED:
 513                         /* Soft state for pmtu is maintained by IP core. */
 514                         return 0;
 515                 default:
 516                         /* All others are translated to HOST_UNREACH.
 517                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 518                            I believe they are just ether pollution. --ANK
 519                          */
 520                         break;
 521                 }
 522                 break;
 523         case ICMP_TIME_EXCEEDED:
 524                 if (code != ICMP_EXC_TTL)
 525                         return 0;
 526                 break;
 527         }
 528
 529         err = -ENOENT;
 530
 531         rcu_read_lock();
 532         t = ipip6_tunnel_lookup(dev_net(skb->dev),
 533                                 skb->dev,
 534                                 iph->daddr,
 535                                 iph->saddr);
 536         if (t == NULL || t->parms.iph.daddr == 0)
 537                 goto out;
 538
 539         err = 0;
 540         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 541                 goto out;
 542
 543         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
 544                 t->err_count++;
 545         else
 546                 t->err_count = 1;
 547         t->err_time = jiffies;
 548 out:
 549         rcu_read_unlock();
 550         return err;
 551 }
 552
 553 static inline void ipip6_ecn_decapsulate(const struct iphdr *iph, struct sk_buff *skb)
 554 {
 555         if (INET_ECN_is_ce(iph->tos))
 556                 IP6_ECN_set_ce(ipv6_hdr(skb));
 557 }
 558
 559 static int ipip6_rcv(struct sk_buff *skb)
 560 {
 561         const struct iphdr *iph;
 562         struct ip_tunnel *tunnel;
 563
 564         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 565                 goto out;
 566
 567         iph = ip_hdr(skb);
 568
 569         rcu_read_lock();
 570         tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
 571                                      iph->saddr, iph->daddr);
 572         if (tunnel != NULL) {
 573                 struct pcpu_tstats *tstats;
 574
 575                 secpath_reset(skb);
 576                 skb->mac_header = skb->network_header;
 577                 skb_reset_network_header(skb);
 578                 IPCB(skb)->flags = 0;
 579                 skb->protocol = htons(ETH_P_IPV6);
 580                 skb->pkt_type = PACKET_HOST;
 581
 582                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
 583                     !isatap_chksrc(skb, iph, tunnel)) {
 584                         tunnel->dev->stats.rx_errors++;
 585                         rcu_read_unlock();
 586                         kfree_skb(skb);
 587                         return 0;
 588                 }
 589
 590                 tstats = this_cpu_ptr(tunnel->dev->tstats);
 591                 tstats->rx_packets++;
 592                 tstats->rx_bytes += skb->len;
 593
 594                 __skb_tunnel_rx(skb, tunnel->dev);
 595
 596                 ipip6_ecn_decapsulate(iph, skb);
 597
 598                 netif_rx(skb);
 599
 600                 rcu_read_unlock();
 601                 return 0;
 602         }
 603
 604         /* no tunnel matched,  let upstream know, ipsec may handle it */
 605         rcu_read_unlock();
 606         return 1;
 607 out:
 608         kfree_skb(skb);
 609         return 0;
 610 }
 611
 612 /*
 613  * Returns the embedded IPv4 address if the IPv6 address
 614  * comes from 6rd / 6to4 (RFC 3056) addr space.
 615  */
 616 static inline
 617 __be32 try_6rd(const struct in6_addr *v6dst, struct ip_tunnel *tunnel)
 618 {
 619         __be32 dst = 0;
 620
 621 #ifdef CONFIG_IPV6_SIT_6RD
 622         if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
 623                               tunnel->ip6rd.prefixlen)) {
 624                 unsigned int pbw0, pbi0;
 625                 int pbi1;
 626                 u32 d;
 627
 628                 pbw0 = tunnel->ip6rd.prefixlen >> 5;
 629                 pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
 630
 631                 d = (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
 632                     tunnel->ip6rd.relay_prefixlen;
 633
 634                 pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
 635                 if (pbi1 > 0)
 636                         d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
 637                              (32 - pbi1);
 638
 639                 dst = tunnel->ip6rd.relay_prefix | htonl(d);
 640         }
 641 #else
 642         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 643                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 644                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 645         }
 646 #endif
 647         return dst;
 648 }
 649
 650 /*
 651  *      This function assumes it is being called from dev_queue_xmit()
 652  *      and that skb is filled properly by that function.
 653  */
 654
 655 static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 656                                      struct net_device *dev)
 657 {
 658         struct ip_tunnel *tunnel = netdev_priv(dev);
 659         struct pcpu_tstats *tstats;
 660         const struct iphdr  *tiph = &tunnel->parms.iph;
 661         const struct ipv6hdr *iph6 = ipv6_hdr(skb);
 662         u8     tos = tunnel->parms.iph.tos;
 663         __be16 df = tiph->frag_off;
 664         struct rtable *rt;                      /* Route to the other host */
 665         struct net_device *tdev;                /* Device to other host */
 666         struct iphdr  *iph;                     /* Our new IP header */
 667         unsigned int max_headroom;              /* The extra header space needed */
 668         __be32 dst = tiph->daddr;
 669         struct flowi4 fl4;
 670         int    mtu;
 671         const struct in6_addr *addr6;
 672         int addr_type;
 673
 674         if (skb->protocol != htons(ETH_P_IPV6))
 675                 goto tx_error;
 676
 677         if (tos == 1)
 678                 tos = ipv6_get_dsfield(iph6);
 679
 680         /* ISATAP (RFC4214) - must come before 6to4 */
 681         if (dev->priv_flags & IFF_ISATAP) {
 682                 struct neighbour *neigh = NULL;
 683
 684                 if (skb_dst(skb))
 685                         neigh = dst_get_neighbour(skb_dst(skb));
 686
 687                 if (neigh == NULL) {
 688                         if (net_ratelimit())
 689                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 690                         goto tx_error;
 691                 }
 692
 693                 addr6 = (const struct in6_addr*)&neigh->primary_key;
 694                 addr_type = ipv6_addr_type(addr6);
 695
 696                 if ((addr_type & IPV6_ADDR_UNICAST) &&
 697                      ipv6_addr_is_isatap(addr6))
 698                         dst = addr6->s6_addr32[3];
 699                 else
 700                         goto tx_error;
 701         }
 702
 703         if (!dst)
 704                 dst = try_6rd(&iph6->daddr, tunnel);
 705
 706         if (!dst) {
 707                 struct neighbour *neigh = NULL;
 708
 709                 if (skb_dst(skb))
 710                         neigh = dst_get_neighbour(skb_dst(skb));
 711
 712                 if (neigh == NULL) {
 713                         if (net_ratelimit())
 714                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 715                         goto tx_error;
 716                 }
 717
 718                 addr6 = (const struct in6_addr*)&neigh->primary_key;
 719                 addr_type = ipv6_addr_type(addr6);
 720
 721                 if (addr_type == IPV6_ADDR_ANY) {
 722                         addr6 = &ipv6_hdr(skb)->daddr;
 723                         addr_type = ipv6_addr_type(addr6);
 724                 }
 725
 726                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 727                         goto tx_error_icmp;
 728
 729                 dst = addr6->s6_addr32[3];
 730         }
 731
 732         rt = ip_route_output_ports(dev_net(dev), &fl4, NULL,
 733                                    dst, tiph->saddr,
 734                                    0, 0,
 735                                    IPPROTO_IPV6, RT_TOS(tos),
 736                                    tunnel->parms.link);
 737         if (IS_ERR(rt)) {
 738                 dev->stats.tx_carrier_errors++;
 739                 goto tx_error_icmp;
 740         }
 741         if (rt->rt_type != RTN_UNICAST) {
 742                 ip_rt_put(rt);
 743                 dev->stats.tx_carrier_errors++;
 744                 goto tx_error_icmp;
 745         }
 746         tdev = rt->dst.dev;
 747
 748         if (tdev == dev) {
 749                 ip_rt_put(rt);
 750                 dev->stats.collisions++;
 751                 goto tx_error;
 752         }
 753
 754         if (df) {
 755                 mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
 756
 757                 if (mtu < 68) {
 758                         dev->stats.collisions++;
 759                         ip_rt_put(rt);
 760                         goto tx_error;
 761                 }
 762
 763                 if (mtu < IPV6_MIN_MTU) {
 764                         mtu = IPV6_MIN_MTU;
 765                         df = 0;
 766                 }
 767
 768                 if (tunnel->parms.iph.daddr && skb_dst(skb))
 769                         skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 770
 771                 if (skb->len > mtu) {
 772                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
 773                         ip_rt_put(rt);
 774                         goto tx_error;
 775                 }
 776         }
 777
 778         if (tunnel->err_count > 0) {
 779                 if (time_before(jiffies,
 780                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
 781                         tunnel->err_count--;
 782                         dst_link_failure(skb);
 783                 } else
 784                         tunnel->err_count = 0;
 785         }
 786
 787         /*
 788          * Okay, now see if we can stuff it in the buffer as-is.
 789          */
 790         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 791
 792         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 793             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 794                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 795                 if (!new_skb) {
 796                         ip_rt_put(rt);
 797                         dev->stats.tx_dropped++;
 798                         dev_kfree_skb(skb);
 799                         return NETDEV_TX_OK;
 800                 }
 801                 if (skb->sk)
 802                         skb_set_owner_w(new_skb, skb->sk);
 803                 dev_kfree_skb(skb);
 804                 skb = new_skb;
 805                 iph6 = ipv6_hdr(skb);
 806         }
 807
 808         skb->transport_header = skb->network_header;
 809         skb_push(skb, sizeof(struct iphdr));
 810         skb_reset_network_header(skb);
 811         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 812         IPCB(skb)->flags = 0;
 813         skb_dst_drop(skb);
 814         skb_dst_set(skb, &rt->dst);
 815
 816         /*
 817          *      Push down and install the IPIP header.
 818          */
 819
 820         iph                     =       ip_hdr(skb);
 821         iph->version            =       4;
 822         iph->ihl                =       sizeof(struct iphdr)>>2;
 823         iph->frag_off           =       df;
 824         iph->protocol           =       IPPROTO_IPV6;
 825         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 826         iph->daddr              =       fl4.daddr;
 827         iph->saddr              =       fl4.saddr;
 828
 829         if ((iph->ttl = tiph->ttl) == 0)
 830                 iph->ttl        =       iph6->hop_limit;
 831
 832         nf_reset(skb);
 833         tstats = this_cpu_ptr(dev->tstats);
 834         __IPTUNNEL_XMIT(tstats, &dev->stats);
 835         return NETDEV_TX_OK;
 836
 837 tx_error_icmp:
 838         dst_link_failure(skb);
 839 tx_error:
 840         dev->stats.tx_errors++;
 841         dev_kfree_skb(skb);
 842         return NETDEV_TX_OK;
 843 }
 844
 845 static void ipip6_tunnel_bind_dev(struct net_device *dev)
 846 {
 847         struct net_device *tdev = NULL;
 848         struct ip_tunnel *tunnel;
 849         const struct iphdr *iph;
 850         struct flowi4 fl4;
 851
 852         tunnel = netdev_priv(dev);
 853         iph = &tunnel->parms.iph;
 854
 855         if (iph->daddr) {
 856                 struct rtable *rt = ip_route_output_ports(dev_net(dev), &fl4, NULL,
 857                                                           iph->daddr, iph->saddr,
 858                                                           0, 0,
 859                                                           IPPROTO_IPV6,
 860                                                           RT_TOS(iph->tos),
 861                                                           tunnel->parms.link);
 862
 863                 if (!IS_ERR(rt)) {
 864                         tdev = rt->dst.dev;
 865                         ip_rt_put(rt);
 866                 }
 867                 dev->flags |= IFF_POINTOPOINT;
 868         }
 869
 870         if (!tdev && tunnel->parms.link)
 871                 tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);
 872
 873         if (tdev) {
 874                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 875                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 876                 if (dev->mtu < IPV6_MIN_MTU)
 877                         dev->mtu = IPV6_MIN_MTU;
 878         }
 879         dev->iflink = tunnel->parms.link;
 880 }
 881
 882 static int
 883 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 884 {
 885         int err = 0;
 886         struct ip_tunnel_parm p;
 887         struct ip_tunnel_prl prl;
 888         struct ip_tunnel *t;
 889         struct net *net = dev_net(dev);
 890         struct sit_net *sitn = net_generic(net, sit_net_id);
 891 #ifdef CONFIG_IPV6_SIT_6RD
 892         struct ip_tunnel_6rd ip6rd;
 893 #endif
 894
 895         switch (cmd) {
 896         case SIOCGETTUNNEL:
 897 #ifdef CONFIG_IPV6_SIT_6RD
 898         case SIOCGET6RD:
 899 #endif
 900                 t = NULL;
 901                 if (dev == sitn->fb_tunnel_dev) {
 902                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 903                                 err = -EFAULT;
 904                                 break;
 905                         }
 906                         t = ipip6_tunnel_locate(net, &p, 0);
 907                 }
 908                 if (t == NULL)
 909                         t = netdev_priv(dev);
 910
 911                 err = -EFAULT;
 912                 if (cmd == SIOCGETTUNNEL) {
 913                         memcpy(&p, &t->parms, sizeof(p));
 914                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p,
 915                                          sizeof(p)))
 916                                 goto done;
 917 #ifdef CONFIG_IPV6_SIT_6RD
 918                 } else {
 919                         ipv6_addr_copy(&ip6rd.prefix, &t->ip6rd.prefix);
 920                         ip6rd.relay_prefix = t->ip6rd.relay_prefix;
 921                         ip6rd.prefixlen = t->ip6rd.prefixlen;
 922                         ip6rd.relay_prefixlen = t->ip6rd.relay_prefixlen;
 923                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &ip6rd,
 924                                          sizeof(ip6rd)))
 925                                 goto done;
 926 #endif
 927                 }
 928                 err = 0;
 929                 break;
 930
 931         case SIOCADDTUNNEL:
 932         case SIOCCHGTUNNEL:
 933                 err = -EPERM;
 934                 if (!capable(CAP_NET_ADMIN))
 935                         goto done;
 936
 937                 err = -EFAULT;
 938                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 939                         goto done;
 940
 941                 err = -EINVAL;
 942                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 943                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 944                         goto done;
 945                 if (p.iph.ttl)
 946                         p.iph.frag_off |= htons(IP_DF);
 947
 948                 t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
 949
 950                 if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 951                         if (t != NULL) {
 952                                 if (t->dev != dev) {
 953                                         err = -EEXIST;
 954                                         break;
 955                                 }
 956                         } else {
 957                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 958                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 959                                         err = -EINVAL;
 960                                         break;
 961                                 }
 962                                 t = netdev_priv(dev);
 963                                 ipip6_tunnel_unlink(sitn, t);
 964                                 synchronize_net();
 965                                 t->parms.iph.saddr = p.iph.saddr;
 966                                 t->parms.iph.daddr = p.iph.daddr;
 967                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 968                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 969                                 ipip6_tunnel_link(sitn, t);
 970                                 netdev_state_change(dev);
 971                         }
 972                 }
 973
 974                 if (t) {
 975                         err = 0;
 976                         if (cmd == SIOCCHGTUNNEL) {
 977                                 t->parms.iph.ttl = p.iph.ttl;
 978                                 t->parms.iph.tos = p.iph.tos;
 979                                 if (t->parms.link != p.link) {
 980                                         t->parms.link = p.link;
 981                                         ipip6_tunnel_bind_dev(dev);
 982                                         netdev_state_change(dev);
 983                                 }
 984                         }
 985                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 986                                 err = -EFAULT;
 987                 } else
 988                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 989                 break;
 990
 991         case SIOCDELTUNNEL:
 992                 err = -EPERM;
 993                 if (!capable(CAP_NET_ADMIN))
 994                         goto done;
 995
 996                 if (dev == sitn->fb_tunnel_dev) {
 997                         err = -EFAULT;
 998                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 999                                 goto done;
1000                         err = -ENOENT;
1001                         if ((t = ipip6_tunnel_locate(net, &p, 0)) == NULL)
1002                                 goto done;
1003                         err = -EPERM;
1004                         if (t == netdev_priv(sitn->fb_tunnel_dev))
1005                                 goto done;
1006                         dev = t->dev;
1007                 }
1008                 unregister_netdevice(dev);
1009                 err = 0;
1010                 break;
1011
1012         case SIOCGETPRL:
1013                 err = -EINVAL;
1014                 if (dev == sitn->fb_tunnel_dev)
1015                         goto done;
1016                 err = -ENOENT;
1017                 if (!(t = netdev_priv(dev)))
1018                         goto done;
1019                 err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
1020                 break;
1021
1022         case SIOCADDPRL:
1023         case SIOCDELPRL:
1024         case SIOCCHGPRL:
1025                 err = -EPERM;
1026                 if (!capable(CAP_NET_ADMIN))
1027                         goto done;
1028                 err = -EINVAL;
1029                 if (dev == sitn->fb_tunnel_dev)
1030                         goto done;
1031                 err = -EFAULT;
1032                 if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
1033                         goto done;
1034                 err = -ENOENT;
1035                 if (!(t = netdev_priv(dev)))
1036                         goto done;
1037
1038                 switch (cmd) {
1039                 case SIOCDELPRL:
1040                         err = ipip6_tunnel_del_prl(t, &prl);
1041                         break;
1042                 case SIOCADDPRL:
1043                 case SIOCCHGPRL:
1044                         err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
1045                         break;
1046                 }
1047                 netdev_state_change(dev);
1048                 break;
1049
1050 #ifdef CONFIG_IPV6_SIT_6RD
1051         case SIOCADD6RD:
1052         case SIOCCHG6RD:
1053         case SIOCDEL6RD:
1054                 err = -EPERM;
1055                 if (!capable(CAP_NET_ADMIN))
1056                         goto done;
1057
1058                 err = -EFAULT;
1059                 if (copy_from_user(&ip6rd, ifr->ifr_ifru.ifru_data,
1060                                    sizeof(ip6rd)))
1061                         goto done;
1062
1063                 t = netdev_priv(dev);
1064
1065                 if (cmd != SIOCDEL6RD) {
1066                         struct in6_addr prefix;
1067                         __be32 relay_prefix;
1068
1069                         err = -EINVAL;
1070                         if (ip6rd.relay_prefixlen > 32 ||
1071                             ip6rd.prefixlen + (32 - ip6rd.relay_prefixlen) > 64)
1072                                 goto done;
1073
1074                         ipv6_addr_prefix(&prefix, &ip6rd.prefix,
1075                                          ip6rd.prefixlen);
1076                         if (!ipv6_addr_equal(&prefix, &ip6rd.prefix))
1077                                 goto done;
1078                         if (ip6rd.relay_prefixlen)
1079                                 relay_prefix = ip6rd.relay_prefix &
1080                                                htonl(0xffffffffUL <<
1081                                                      (32 - ip6rd.relay_prefixlen));
1082                         else
1083                                 relay_prefix = 0;
1084                         if (relay_prefix != ip6rd.relay_prefix)
1085                                 goto done;
1086
1087                         ipv6_addr_copy(&t->ip6rd.prefix, &prefix);
1088                         t->ip6rd.relay_prefix = relay_prefix;
1089                         t->ip6rd.prefixlen = ip6rd.prefixlen;
1090                         t->ip6rd.relay_prefixlen = ip6rd.relay_prefixlen;
1091                 } else
1092                         ipip6_tunnel_clone_6rd(dev, sitn);
1093
1094                 err = 0;
1095                 break;
1096 #endif
1097
1098         default:
1099                 err = -EINVAL;
1100         }
1101
1102 done:
1103         return err;
1104 }
1105
1106 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1107 {
1108         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
1109                 return -EINVAL;
1110         dev->mtu = new_mtu;
1111         return 0;
1112 }
1113
1114 static const struct net_device_ops ipip6_netdev_ops = {
1115         .ndo_uninit     = ipip6_tunnel_uninit,
1116         .ndo_start_xmit = ipip6_tunnel_xmit,
1117         .ndo_do_ioctl   = ipip6_tunnel_ioctl,
1118         .ndo_change_mtu = ipip6_tunnel_change_mtu,
1119         .ndo_get_stats  = ipip6_get_stats,
1120 };
1121
1122 static void ipip6_dev_free(struct net_device *dev)
1123 {
1124         free_percpu(dev->tstats);
1125         free_netdev(dev);
1126 }
1127
1128 static void ipip6_tunnel_setup(struct net_device *dev)
1129 {
1130         dev->netdev_ops         = &ipip6_netdev_ops;
1131         dev->destructor         = ipip6_dev_free;
1132
1133         dev->type               = ARPHRD_SIT;
1134         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
1135         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
1136         dev->flags              = IFF_NOARP;
1137         dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
1138         dev->iflink             = 0;
1139         dev->addr_len           = 4;
1140         dev->features           |= NETIF_F_NETNS_LOCAL;
1141         dev->features           |= NETIF_F_LLTX;
1142 }
1143
1144 static int ipip6_tunnel_init(struct net_device *dev)
1145 {
1146         struct ip_tunnel *tunnel = netdev_priv(dev);
1147
1148         tunnel->dev = dev;
1149
1150         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1151         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1152
1153         ipip6_tunnel_bind_dev(dev);
1154         dev->tstats = alloc_percpu(struct pcpu_tstats);
1155         if (!dev->tstats)
1156                 return -ENOMEM;
1157
1158         return 0;
1159 }
1160
1161 static int __net_init ipip6_fb_tunnel_init(struct net_device *dev)
1162 {
1163         struct ip_tunnel *tunnel = netdev_priv(dev);
1164         struct iphdr *iph = &tunnel->parms.iph;
1165         struct net *net = dev_net(dev);
1166         struct sit_net *sitn = net_generic(net, sit_net_id);
1167
1168         tunnel->dev = dev;
1169         strcpy(tunnel->parms.name, dev->name);
1170
1171         iph->version            = 4;
1172         iph->protocol           = IPPROTO_IPV6;
1173         iph->ihl                = 5;
1174         iph->ttl                = 64;
1175
1176         dev->tstats = alloc_percpu(struct pcpu_tstats);
1177         if (!dev->tstats)
1178                 return -ENOMEM;
1179         dev_hold(dev);
1180         RCU_INIT_POINTER(sitn->tunnels_wc[0], tunnel);
1181         return 0;
1182 }
1183
1184 static struct xfrm_tunnel sit_handler __read_mostly = {
1185         .handler        =       ipip6_rcv,
1186         .err_handler    =       ipip6_err,
1187         .priority       =       1,
1188 };
1189
1190 static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_head *head)
1191 {
1192         int prio;
1193
1194         for (prio = 1; prio < 4; prio++) {
1195                 int h;
1196                 for (h = 0; h < HASH_SIZE; h++) {
1197                         struct ip_tunnel *t;
1198
1199                         t = rtnl_dereference(sitn->tunnels[prio][h]);
1200                         while (t != NULL) {
1201                                 unregister_netdevice_queue(t->dev, head);
1202                                 t = rtnl_dereference(t->next);
1203                         }
1204                 }
1205         }
1206 }
1207
1208 static int __net_init sit_init_net(struct net *net)
1209 {
1210         struct sit_net *sitn = net_generic(net, sit_net_id);
1211         struct ip_tunnel *t;
1212         int err;
1213
1214         sitn->tunnels[0] = sitn->tunnels_wc;
1215         sitn->tunnels[1] = sitn->tunnels_l;
1216         sitn->tunnels[2] = sitn->tunnels_r;
1217         sitn->tunnels[3] = sitn->tunnels_r_l;
1218
1219         sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
1220                                            ipip6_tunnel_setup);
1221         if (!sitn->fb_tunnel_dev) {
1222                 err = -ENOMEM;
1223                 goto err_alloc_dev;
1224         }
1225         dev_net_set(sitn->fb_tunnel_dev, net);
1226
1227         err = ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
1228         if (err)
1229                 goto err_dev_free;
1230
1231         ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
1232
1233         if ((err = register_netdev(sitn->fb_tunnel_dev)))
1234                 goto err_reg_dev;
1235
1236         t = netdev_priv(sitn->fb_tunnel_dev);
1237
1238         strcpy(t->parms.name, sitn->fb_tunnel_dev->name);
1239         return 0;
1240
1241 err_reg_dev:
1242         dev_put(sitn->fb_tunnel_dev);
1243 err_dev_free:
1244         ipip6_dev_free(sitn->fb_tunnel_dev);
1245 err_alloc_dev:
1246         return err;
1247 }
1248
1249 static void __net_exit sit_exit_net(struct net *net)
1250 {
1251         struct sit_net *sitn = net_generic(net, sit_net_id);
1252         LIST_HEAD(list);
1253
1254         rtnl_lock();
1255         sit_destroy_tunnels(sitn, &list);
1256         unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);
1257         unregister_netdevice_many(&list);
1258         rtnl_unlock();
1259 }
1260
1261 static struct pernet_operations sit_net_ops = {
1262         .init = sit_init_net,
1263         .exit = sit_exit_net,
1264         .id   = &sit_net_id,
1265         .size = sizeof(struct sit_net),
1266 };
1267
1268 static void __exit sit_cleanup(void)
1269 {
1270         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1271
1272         unregister_pernet_device(&sit_net_ops);
1273         rcu_barrier(); /* Wait for completion of call_rcu()'s */
1274 }
1275
1276 static int __init sit_init(void)
1277 {
1278         int err;
1279
1280         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
1281
1282         err = register_pernet_device(&sit_net_ops);
1283         if (err < 0)
1284                 return err;
1285         err = xfrm4_tunnel_register(&sit_handler, AF_INET6);
1286         if (err < 0) {
1287                 unregister_pernet_device(&sit_net_ops);
1288                 printk(KERN_INFO "sit init: Can't add protocol\n");
1289         }
1290         return err;
1291 }
1292
1293 module_init(sit_init);
1294 module_exit(sit_cleanup);
1295 MODULE_LICENSE("GPL");
1296 MODULE_ALIAS_NETDEV("sit0");