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         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 610         rcu_read_unlock();
 611 out:
 612         kfree_skb(skb);
 613         return 0;
 614 }
 615
 616 /*
 617  * Returns the embedded IPv4 address if the IPv6 address
 618  * comes from 6rd / 6to4 (RFC 3056) addr space.
 619  */
 620 static inline
 621 __be32 try_6rd(struct in6_addr *v6dst, struct ip_tunnel *tunnel)
 622 {
 623         __be32 dst = 0;
 624
 625 #ifdef CONFIG_IPV6_SIT_6RD
 626         if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
 627                               tunnel->ip6rd.prefixlen)) {
 628                 unsigned int pbw0, pbi0;
 629                 int pbi1;
 630                 u32 d;
 631
 632                 pbw0 = tunnel->ip6rd.prefixlen >> 5;
 633                 pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
 634
 635                 d = (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
 636                     tunnel->ip6rd.relay_prefixlen;
 637
 638                 pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
 639                 if (pbi1 > 0)
 640                         d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
 641                              (32 - pbi1);
 642
 643                 dst = tunnel->ip6rd.relay_prefix | htonl(d);
 644         }
 645 #else
 646         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 647                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 648                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 649         }
 650 #endif
 651         return dst;
 652 }
 653
 654 /*
 655  *      This function assumes it is being called from dev_queue_xmit()
 656  *      and that skb is filled properly by that function.
 657  */
 658
 659 static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 660                                      struct net_device *dev)
 661 {
 662         struct ip_tunnel *tunnel = netdev_priv(dev);
 663         struct pcpu_tstats *tstats;
 664         struct iphdr  *tiph = &tunnel->parms.iph;
 665         struct ipv6hdr *iph6 = ipv6_hdr(skb);
 666         u8     tos = tunnel->parms.iph.tos;
 667         __be16 df = tiph->frag_off;
 668         struct rtable *rt;                      /* Route to the other host */
 669         struct net_device *tdev;                /* Device to other host */
 670         struct iphdr  *iph;                     /* Our new IP header */
 671         unsigned int max_headroom;              /* The extra header space needed */
 672         __be32 dst = tiph->daddr;
 673         int    mtu;
 674         struct in6_addr *addr6;
 675         int addr_type;
 676
 677         if (skb->protocol != htons(ETH_P_IPV6))
 678                 goto tx_error;
 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 = skb_dst(skb)->neighbour;
 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 = (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 = skb_dst(skb)->neighbour;
 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 = (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         {
 733                 struct flowi fl = { .nl_u = { .ip4_u =
 734                                               { .daddr = dst,
 735                                                 .saddr = tiph->saddr,
 736                                                 .tos = RT_TOS(tos) } },
 737                                     .oif = tunnel->parms.link,
 738                                     .proto = IPPROTO_IPV6 };
 739                 if (ip_route_output_key(dev_net(dev), &rt, &fl)) {
 740                         dev->stats.tx_carrier_errors++;
 741                         goto tx_error_icmp;
 742                 }
 743         }
 744         if (rt->rt_type != RTN_UNICAST) {
 745                 ip_rt_put(rt);
 746                 dev->stats.tx_carrier_errors++;
 747                 goto tx_error_icmp;
 748         }
 749         tdev = rt->dst.dev;
 750
 751         if (tdev == dev) {
 752                 ip_rt_put(rt);
 753                 dev->stats.collisions++;
 754                 goto tx_error;
 755         }
 756
 757         if (df) {
 758                 mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
 759
 760                 if (mtu < 68) {
 761                         dev->stats.collisions++;
 762                         ip_rt_put(rt);
 763                         goto tx_error;
 764                 }
 765
 766                 if (mtu < IPV6_MIN_MTU) {
 767                         mtu = IPV6_MIN_MTU;
 768                         df = 0;
 769                 }
 770
 771                 if (tunnel->parms.iph.daddr && skb_dst(skb))
 772                         skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 773
 774                 if (skb->len > mtu) {
 775                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
 776                         ip_rt_put(rt);
 777                         goto tx_error;
 778                 }
 779         }
 780
 781         if (tunnel->err_count > 0) {
 782                 if (time_before(jiffies,
 783                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
 784                         tunnel->err_count--;
 785                         dst_link_failure(skb);
 786                 } else
 787                         tunnel->err_count = 0;
 788         }
 789
 790         /*
 791          * Okay, now see if we can stuff it in the buffer as-is.
 792          */
 793         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 794
 795         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 796             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 797                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 798                 if (!new_skb) {
 799                         ip_rt_put(rt);
 800                         dev->stats.tx_dropped++;
 801                         dev_kfree_skb(skb);
 802                         return NETDEV_TX_OK;
 803                 }
 804                 if (skb->sk)
 805                         skb_set_owner_w(new_skb, skb->sk);
 806                 dev_kfree_skb(skb);
 807                 skb = new_skb;
 808                 iph6 = ipv6_hdr(skb);
 809         }
 810
 811         skb->transport_header = skb->network_header;
 812         skb_push(skb, sizeof(struct iphdr));
 813         skb_reset_network_header(skb);
 814         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 815         IPCB(skb)->flags = 0;
 816         skb_dst_drop(skb);
 817         skb_dst_set(skb, &rt->dst);
 818
 819         /*
 820          *      Push down and install the IPIP header.
 821          */
 822
 823         iph                     =       ip_hdr(skb);
 824         iph->version            =       4;
 825         iph->ihl                =       sizeof(struct iphdr)>>2;
 826         iph->frag_off           =       df;
 827         iph->protocol           =       IPPROTO_IPV6;
 828         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 829         iph->daddr              =       rt->rt_dst;
 830         iph->saddr              =       rt->rt_src;
 831
 832         if ((iph->ttl = tiph->ttl) == 0)
 833                 iph->ttl        =       iph6->hop_limit;
 834
 835         nf_reset(skb);
 836         tstats = this_cpu_ptr(dev->tstats);
 837         __IPTUNNEL_XMIT(tstats, &dev->stats);
 838         return NETDEV_TX_OK;
 839
 840 tx_error_icmp:
 841         dst_link_failure(skb);
 842 tx_error:
 843         dev->stats.tx_errors++;
 844         dev_kfree_skb(skb);
 845         return NETDEV_TX_OK;
 846 }
 847
 848 static void ipip6_tunnel_bind_dev(struct net_device *dev)
 849 {
 850         struct net_device *tdev = NULL;
 851         struct ip_tunnel *tunnel;
 852         struct iphdr *iph;
 853
 854         tunnel = netdev_priv(dev);
 855         iph = &tunnel->parms.iph;
 856
 857         if (iph->daddr) {
 858                 struct flowi fl = { .nl_u = { .ip4_u =
 859                                               { .daddr = iph->daddr,
 860                                                 .saddr = iph->saddr,
 861                                                 .tos = RT_TOS(iph->tos) } },
 862                                     .oif = tunnel->parms.link,
 863                                     .proto = IPPROTO_IPV6 };
 864                 struct rtable *rt;
 865                 if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 866                         tdev = rt->dst.dev;
 867                         ip_rt_put(rt);
 868                 }
 869                 dev->flags |= IFF_POINTOPOINT;
 870         }
 871
 872         if (!tdev && tunnel->parms.link)
 873                 tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);
 874
 875         if (tdev) {
 876                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 877                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 878                 if (dev->mtu < IPV6_MIN_MTU)
 879                         dev->mtu = IPV6_MIN_MTU;
 880         }
 881         dev->iflink = tunnel->parms.link;
 882 }
 883
 884 static int
 885 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 886 {
 887         int err = 0;
 888         struct ip_tunnel_parm p;
 889         struct ip_tunnel_prl prl;
 890         struct ip_tunnel *t;
 891         struct net *net = dev_net(dev);
 892         struct sit_net *sitn = net_generic(net, sit_net_id);
 893 #ifdef CONFIG_IPV6_SIT_6RD
 894         struct ip_tunnel_6rd ip6rd;
 895 #endif
 896
 897         switch (cmd) {
 898         case SIOCGETTUNNEL:
 899 #ifdef CONFIG_IPV6_SIT_6RD
 900         case SIOCGET6RD:
 901 #endif
 902                 t = NULL;
 903                 if (dev == sitn->fb_tunnel_dev) {
 904                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 905                                 err = -EFAULT;
 906                                 break;
 907                         }
 908                         t = ipip6_tunnel_locate(net, &p, 0);
 909                 }
 910                 if (t == NULL)
 911                         t = netdev_priv(dev);
 912
 913                 err = -EFAULT;
 914                 if (cmd == SIOCGETTUNNEL) {
 915                         memcpy(&p, &t->parms, sizeof(p));
 916                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p,
 917                                          sizeof(p)))
 918                                 goto done;
 919 #ifdef CONFIG_IPV6_SIT_6RD
 920                 } else {
 921                         ipv6_addr_copy(&ip6rd.prefix, &t->ip6rd.prefix);
 922                         ip6rd.relay_prefix = t->ip6rd.relay_prefix;
 923                         ip6rd.prefixlen = t->ip6rd.prefixlen;
 924                         ip6rd.relay_prefixlen = t->ip6rd.relay_prefixlen;
 925                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &ip6rd,
 926                                          sizeof(ip6rd)))
 927                                 goto done;
 928 #endif
 929                 }
 930                 err = 0;
 931                 break;
 932
 933         case SIOCADDTUNNEL:
 934         case SIOCCHGTUNNEL:
 935                 err = -EPERM;
 936                 if (!capable(CAP_NET_ADMIN))
 937                         goto done;
 938
 939                 err = -EFAULT;
 940                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 941                         goto done;
 942
 943                 err = -EINVAL;
 944                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 945                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 946                         goto done;
 947                 if (p.iph.ttl)
 948                         p.iph.frag_off |= htons(IP_DF);
 949
 950                 t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
 951
 952                 if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 953                         if (t != NULL) {
 954                                 if (t->dev != dev) {
 955                                         err = -EEXIST;
 956                                         break;
 957                                 }
 958                         } else {
 959                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 960                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 961                                         err = -EINVAL;
 962                                         break;
 963                                 }
 964                                 t = netdev_priv(dev);
 965                                 ipip6_tunnel_unlink(sitn, t);
 966                                 synchronize_net();
 967                                 t->parms.iph.saddr = p.iph.saddr;
 968                                 t->parms.iph.daddr = p.iph.daddr;
 969                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 970                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 971                                 ipip6_tunnel_link(sitn, t);
 972                                 netdev_state_change(dev);
 973                         }
 974                 }
 975
 976                 if (t) {
 977                         err = 0;
 978                         if (cmd == SIOCCHGTUNNEL) {
 979                                 t->parms.iph.ttl = p.iph.ttl;
 980                                 t->parms.iph.tos = p.iph.tos;
 981                                 if (t->parms.link != p.link) {
 982                                         t->parms.link = p.link;
 983                                         ipip6_tunnel_bind_dev(dev);
 984                                         netdev_state_change(dev);
 985                                 }
 986                         }
 987                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 988                                 err = -EFAULT;
 989                 } else
 990                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 991                 break;
 992
 993         case SIOCDELTUNNEL:
 994                 err = -EPERM;
 995                 if (!capable(CAP_NET_ADMIN))
 996                         goto done;
 997
 998                 if (dev == sitn->fb_tunnel_dev) {
 999                         err = -EFAULT;
1000                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
1001                                 goto done;
1002                         err = -ENOENT;
1003                         if ((t = ipip6_tunnel_locate(net, &p, 0)) == NULL)
1004                                 goto done;
1005                         err = -EPERM;
1006                         if (t == netdev_priv(sitn->fb_tunnel_dev))
1007                                 goto done;
1008                         dev = t->dev;
1009                 }
1010                 unregister_netdevice(dev);
1011                 err = 0;
1012                 break;
1013
1014         case SIOCGETPRL:
1015                 err = -EINVAL;
1016                 if (dev == sitn->fb_tunnel_dev)
1017                         goto done;
1018                 err = -ENOENT;
1019                 if (!(t = netdev_priv(dev)))
1020                         goto done;
1021                 err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
1022                 break;
1023
1024         case SIOCADDPRL:
1025         case SIOCDELPRL:
1026         case SIOCCHGPRL:
1027                 err = -EPERM;
1028                 if (!capable(CAP_NET_ADMIN))
1029                         goto done;
1030                 err = -EINVAL;
1031                 if (dev == sitn->fb_tunnel_dev)
1032                         goto done;
1033                 err = -EFAULT;
1034                 if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
1035                         goto done;
1036                 err = -ENOENT;
1037                 if (!(t = netdev_priv(dev)))
1038                         goto done;
1039
1040                 switch (cmd) {
1041                 case SIOCDELPRL:
1042                         err = ipip6_tunnel_del_prl(t, &prl);
1043                         break;
1044                 case SIOCADDPRL:
1045                 case SIOCCHGPRL:
1046                         err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
1047                         break;
1048                 }
1049                 netdev_state_change(dev);
1050                 break;
1051
1052 #ifdef CONFIG_IPV6_SIT_6RD
1053         case SIOCADD6RD:
1054         case SIOCCHG6RD:
1055         case SIOCDEL6RD:
1056                 err = -EPERM;
1057                 if (!capable(CAP_NET_ADMIN))
1058                         goto done;
1059
1060                 err = -EFAULT;
1061                 if (copy_from_user(&ip6rd, ifr->ifr_ifru.ifru_data,
1062                                    sizeof(ip6rd)))
1063                         goto done;
1064
1065                 t = netdev_priv(dev);
1066
1067                 if (cmd != SIOCDEL6RD) {
1068                         struct in6_addr prefix;
1069                         __be32 relay_prefix;
1070
1071                         err = -EINVAL;
1072                         if (ip6rd.relay_prefixlen > 32 ||
1073                             ip6rd.prefixlen + (32 - ip6rd.relay_prefixlen) > 64)
1074                                 goto done;
1075
1076                         ipv6_addr_prefix(&prefix, &ip6rd.prefix,
1077                                          ip6rd.prefixlen);
1078                         if (!ipv6_addr_equal(&prefix, &ip6rd.prefix))
1079                                 goto done;
1080                         if (ip6rd.relay_prefixlen)
1081                                 relay_prefix = ip6rd.relay_prefix &
1082                                                htonl(0xffffffffUL <<
1083                                                      (32 - ip6rd.relay_prefixlen));
1084                         else
1085                                 relay_prefix = 0;
1086                         if (relay_prefix != ip6rd.relay_prefix)
1087                                 goto done;
1088
1089                         ipv6_addr_copy(&t->ip6rd.prefix, &prefix);
1090                         t->ip6rd.relay_prefix = relay_prefix;
1091                         t->ip6rd.prefixlen = ip6rd.prefixlen;
1092                         t->ip6rd.relay_prefixlen = ip6rd.relay_prefixlen;
1093                 } else
1094                         ipip6_tunnel_clone_6rd(dev, sitn);
1095
1096                 err = 0;
1097                 break;
1098 #endif
1099
1100         default:
1101                 err = -EINVAL;
1102         }
1103
1104 done:
1105         return err;
1106 }
1107
1108 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1109 {
1110         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
1111                 return -EINVAL;
1112         dev->mtu = new_mtu;
1113         return 0;
1114 }
1115
1116 static const struct net_device_ops ipip6_netdev_ops = {
1117         .ndo_uninit     = ipip6_tunnel_uninit,
1118         .ndo_start_xmit = ipip6_tunnel_xmit,
1119         .ndo_do_ioctl   = ipip6_tunnel_ioctl,
1120         .ndo_change_mtu = ipip6_tunnel_change_mtu,
1121         .ndo_get_stats  = ipip6_get_stats,
1122 };
1123
1124 static void ipip6_dev_free(struct net_device *dev)
1125 {
1126         free_percpu(dev->tstats);
1127         free_netdev(dev);
1128 }
1129
1130 static void ipip6_tunnel_setup(struct net_device *dev)
1131 {
1132         dev->netdev_ops         = &ipip6_netdev_ops;
1133         dev->destructor         = ipip6_dev_free;
1134
1135         dev->type               = ARPHRD_SIT;
1136         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
1137         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
1138         dev->flags              = IFF_NOARP;
1139         dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
1140         dev->iflink             = 0;
1141         dev->addr_len           = 4;
1142         dev->features           |= NETIF_F_NETNS_LOCAL;
1143         dev->features           |= NETIF_F_LLTX;
1144 }
1145
1146 static int ipip6_tunnel_init(struct net_device *dev)
1147 {
1148         struct ip_tunnel *tunnel = netdev_priv(dev);
1149
1150         tunnel->dev = dev;
1151         strcpy(tunnel->parms.name, dev->name);
1152
1153         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1154         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1155
1156         ipip6_tunnel_bind_dev(dev);
1157         dev->tstats = alloc_percpu(struct pcpu_tstats);
1158         if (!dev->tstats)
1159                 return -ENOMEM;
1160
1161         return 0;
1162 }
1163
1164 static int __net_init ipip6_fb_tunnel_init(struct net_device *dev)
1165 {
1166         struct ip_tunnel *tunnel = netdev_priv(dev);
1167         struct iphdr *iph = &tunnel->parms.iph;
1168         struct net *net = dev_net(dev);
1169         struct sit_net *sitn = net_generic(net, sit_net_id);
1170
1171         tunnel->dev = dev;
1172         strcpy(tunnel->parms.name, dev->name);
1173
1174         iph->version            = 4;
1175         iph->protocol           = IPPROTO_IPV6;
1176         iph->ihl                = 5;
1177         iph->ttl                = 64;
1178
1179         dev->tstats = alloc_percpu(struct pcpu_tstats);
1180         if (!dev->tstats)
1181                 return -ENOMEM;
1182         dev_hold(dev);
1183         sitn->tunnels_wc[0]     = tunnel;
1184         return 0;
1185 }
1186
1187 static struct xfrm_tunnel sit_handler __read_mostly = {
1188         .handler        =       ipip6_rcv,
1189         .err_handler    =       ipip6_err,
1190         .priority       =       1,
1191 };
1192
1193 static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_head *head)
1194 {
1195         int prio;
1196
1197         for (prio = 1; prio < 4; prio++) {
1198                 int h;
1199                 for (h = 0; h < HASH_SIZE; h++) {
1200                         struct ip_tunnel *t = sitn->tunnels[prio][h];
1201
1202                         while (t != NULL) {
1203                                 unregister_netdevice_queue(t->dev, head);
1204                                 t = t->next;
1205                         }
1206                 }
1207         }
1208 }
1209
1210 static int __net_init sit_init_net(struct net *net)
1211 {
1212         struct sit_net *sitn = net_generic(net, sit_net_id);
1213         int err;
1214
1215         sitn->tunnels[0] = sitn->tunnels_wc;
1216         sitn->tunnels[1] = sitn->tunnels_l;
1217         sitn->tunnels[2] = sitn->tunnels_r;
1218         sitn->tunnels[3] = sitn->tunnels_r_l;
1219
1220         sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
1221                                            ipip6_tunnel_setup);
1222         if (!sitn->fb_tunnel_dev) {
1223                 err = -ENOMEM;
1224                 goto err_alloc_dev;
1225         }
1226         dev_net_set(sitn->fb_tunnel_dev, net);
1227
1228         err = ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
1229         if (err)
1230                 goto err_dev_free;
1231
1232         ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
1233
1234         if ((err = register_netdev(sitn->fb_tunnel_dev)))
1235                 goto err_reg_dev;
1236
1237         return 0;
1238
1239 err_reg_dev:
1240         dev_put(sitn->fb_tunnel_dev);
1241 err_dev_free:
1242         ipip6_dev_free(sitn->fb_tunnel_dev);
1243 err_alloc_dev:
1244         return err;
1245 }
1246
1247 static void __net_exit sit_exit_net(struct net *net)
1248 {
1249         struct sit_net *sitn = net_generic(net, sit_net_id);
1250         LIST_HEAD(list);
1251
1252         rtnl_lock();
1253         sit_destroy_tunnels(sitn, &list);
1254         unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);
1255         unregister_netdevice_many(&list);
1256         rtnl_unlock();
1257 }
1258
1259 static struct pernet_operations sit_net_ops = {
1260         .init = sit_init_net,
1261         .exit = sit_exit_net,
1262         .id   = &sit_net_id,
1263         .size = sizeof(struct sit_net),
1264 };
1265
1266 static void __exit sit_cleanup(void)
1267 {
1268         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1269
1270         unregister_pernet_device(&sit_net_ops);
1271         rcu_barrier(); /* Wait for completion of call_rcu()'s */
1272 }
1273
1274 static int __init sit_init(void)
1275 {
1276         int err;
1277
1278         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
1279
1280         err = register_pernet_device(&sit_net_ops);
1281         if (err < 0)
1282                 return err;
1283         err = xfrm4_tunnel_register(&sit_handler, AF_INET6);
1284         if (err < 0) {
1285                 unregister_pernet_device(&sit_net_ops);
1286                 printk(KERN_INFO "sit init: Can't add protocol\n");
1287         }
1288         return err;
1289 }
1290
1291 module_init(sit_init);
1292 module_exit(sit_cleanup);
1293 MODULE_LICENSE("GPL");
1294 MODULE_ALIAS("sit0");