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  * Sascha Hlusiak <mail@saschahlusiak.de>:      stateless autoconf for isatap
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/capability.h>
  23 #include <linux/errno.h>
  24 #include <linux/types.h>
  25 #include <linux/socket.h>
  26 #include <linux/sockios.h>
  27 #include <linux/net.h>
  28 #include <linux/in6.h>
  29 #include <linux/netdevice.h>
  30 #include <linux/if_arp.h>
  31 #include <linux/icmp.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 void ipip6_fb_tunnel_init(struct net_device *dev);
  67 static void ipip6_tunnel_init(struct net_device *dev);
  68 static void ipip6_tunnel_setup(struct net_device *dev);
  69
  70 static int sit_net_id;
  71 struct sit_net {
  72         struct ip_tunnel *tunnels_r_l[HASH_SIZE];
  73         struct ip_tunnel *tunnels_r[HASH_SIZE];
  74         struct ip_tunnel *tunnels_l[HASH_SIZE];
  75         struct ip_tunnel *tunnels_wc[1];
  76         struct ip_tunnel **tunnels[4];
  77
  78         struct net_device *fb_tunnel_dev;
  79 };
  80
  81 static DEFINE_RWLOCK(ipip6_lock);
  82
  83 static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,
  84                 struct net_device *dev, __be32 remote, __be32 local)
  85 {
  86         unsigned h0 = HASH(remote);
  87         unsigned h1 = HASH(local);
  88         struct ip_tunnel *t;
  89         struct sit_net *sitn = net_generic(net, sit_net_id);
  90
  91         for (t = sitn->tunnels_r_l[h0^h1]; t; t = t->next) {
  92                 if (local == t->parms.iph.saddr &&
  93                     remote == t->parms.iph.daddr &&
  94                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
  95                     (t->dev->flags & IFF_UP))
  96                         return t;
  97         }
  98         for (t = sitn->tunnels_r[h0]; t; t = t->next) {
  99                 if (remote == t->parms.iph.daddr &&
 100                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 101                     (t->dev->flags & IFF_UP))
 102                         return t;
 103         }
 104         for (t = sitn->tunnels_l[h1]; t; t = t->next) {
 105                 if (local == t->parms.iph.saddr &&
 106                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 107                     (t->dev->flags & IFF_UP))
 108                         return t;
 109         }
 110         t = sitn->tunnels_wc[0];
 111         if ((t != NULL) && (t->dev->flags & IFF_UP))
 112                 return t;
 113         return NULL;
 114 }
 115
 116 static struct ip_tunnel **__ipip6_bucket(struct sit_net *sitn,
 117                 struct ip_tunnel_parm *parms)
 118 {
 119         __be32 remote = parms->iph.daddr;
 120         __be32 local = parms->iph.saddr;
 121         unsigned h = 0;
 122         int prio = 0;
 123
 124         if (remote) {
 125                 prio |= 2;
 126                 h ^= HASH(remote);
 127         }
 128         if (local) {
 129                 prio |= 1;
 130                 h ^= HASH(local);
 131         }
 132         return &sitn->tunnels[prio][h];
 133 }
 134
 135 static inline struct ip_tunnel **ipip6_bucket(struct sit_net *sitn,
 136                 struct ip_tunnel *t)
 137 {
 138         return __ipip6_bucket(sitn, &t->parms);
 139 }
 140
 141 static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
 142 {
 143         struct ip_tunnel **tp;
 144
 145         for (tp = ipip6_bucket(sitn, t); *tp; tp = &(*tp)->next) {
 146                 if (t == *tp) {
 147                         write_lock_bh(&ipip6_lock);
 148                         *tp = t->next;
 149                         write_unlock_bh(&ipip6_lock);
 150                         break;
 151                 }
 152         }
 153 }
 154
 155 static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
 156 {
 157         struct ip_tunnel **tp = ipip6_bucket(sitn, t);
 158
 159         t->next = *tp;
 160         write_lock_bh(&ipip6_lock);
 161         *tp = t;
 162         write_unlock_bh(&ipip6_lock);
 163 }
 164
 165 static struct ip_tunnel * ipip6_tunnel_locate(struct net *net,
 166                 struct ip_tunnel_parm *parms, int create)
 167 {
 168         __be32 remote = parms->iph.daddr;
 169         __be32 local = parms->iph.saddr;
 170         struct ip_tunnel *t, **tp, *nt;
 171         struct net_device *dev;
 172         char name[IFNAMSIZ];
 173         struct sit_net *sitn = net_generic(net, sit_net_id);
 174
 175         for (tp = __ipip6_bucket(sitn, parms); (t = *tp) != NULL; tp = &t->next) {
 176                 if (local == t->parms.iph.saddr &&
 177                     remote == t->parms.iph.daddr &&
 178                     parms->link == t->parms.link) {
 179                         if (create)
 180                                 return NULL;
 181                         else
 182                                 return t;
 183                 }
 184         }
 185         if (!create)
 186                 goto failed;
 187
 188         if (parms->name[0])
 189                 strlcpy(name, parms->name, IFNAMSIZ);
 190         else
 191                 sprintf(name, "sit%%d");
 192
 193         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
 194         if (dev == NULL)
 195                 return NULL;
 196
 197         dev_net_set(dev, net);
 198
 199         if (strchr(name, '%')) {
 200                 if (dev_alloc_name(dev, name) < 0)
 201                         goto failed_free;
 202         }
 203
 204         nt = netdev_priv(dev);
 205
 206         nt->parms = *parms;
 207         ipip6_tunnel_init(dev);
 208
 209         if (parms->i_flags & SIT_ISATAP)
 210                 dev->priv_flags |= IFF_ISATAP;
 211
 212         if (register_netdevice(dev) < 0)
 213                 goto failed_free;
 214
 215         dev_hold(dev);
 216
 217         ipip6_tunnel_link(sitn, nt);
 218         return nt;
 219
 220 failed_free:
 221         free_netdev(dev);
 222 failed:
 223         return NULL;
 224 }
 225
 226 static void ipip6_tunnel_rs_timer(unsigned long data)
 227 {
 228         struct ip_tunnel_prl_entry *p = (struct ip_tunnel_prl_entry *) data;
 229         struct inet6_dev *ifp;
 230         struct inet6_ifaddr *addr;
 231
 232         spin_lock(&p->lock);
 233         ifp = __in6_dev_get(p->tunnel->dev);
 234
 235         read_lock_bh(&ifp->lock);
 236         for (addr = ifp->addr_list; addr; addr = addr->if_next) {
 237                 struct in6_addr rtr;
 238
 239                 if (!(ipv6_addr_type(&addr->addr) & IPV6_ADDR_LINKLOCAL))
 240                         continue;
 241
 242                 /* Send RS to guessed linklocal address of router
 243                  *
 244                  * Better: send to ff02::2 encapsuled in unicast directly
 245                  * to router-v4 instead of guessing the v6 address.
 246                  *
 247                  * Cisco/Windows seem to not set the u/l bit correctly,
 248                  * so we won't guess right.
 249                  */
 250                 ipv6_addr_set(&rtr,  htonl(0xFE800000), 0, 0, 0);
 251                 if (!__ipv6_isatap_ifid(rtr.s6_addr + 8,
 252                                         p->addr)) {
 253                         ndisc_send_rs(p->tunnel->dev, &addr->addr, &rtr);
 254                 }
 255         }
 256         read_unlock_bh(&ifp->lock);
 257
 258         mod_timer(&p->rs_timer, jiffies + HZ * p->rs_delay);
 259         spin_unlock(&p->lock);
 260
 261         return;
 262 }
 263
 264 static struct ip_tunnel_prl_entry *
 265 __ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
 266 {
 267         struct ip_tunnel_prl_entry *p = (struct ip_tunnel_prl_entry *)NULL;
 268
 269         for (p = t->prl; p; p = p->next)
 270                 if (p->addr == addr)
 271                         break;
 272         return p;
 273
 274 }
 275
 276 static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
 277                                 struct ip_tunnel_prl __user *a)
 278 {
 279         struct ip_tunnel_prl kprl, *kp;
 280         struct ip_tunnel_prl_entry *prl;
 281         unsigned int cmax, c = 0, ca, len;
 282         int ret = 0;
 283
 284         if (copy_from_user(&kprl, a, sizeof(kprl)))
 285                 return -EFAULT;
 286         cmax = kprl.datalen / sizeof(kprl);
 287         if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
 288                 cmax = 1;
 289
 290         /* For simple GET or for root users,
 291          * we try harder to allocate.
 292          */
 293         kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
 294                 kcalloc(cmax, sizeof(*kp), GFP_KERNEL) :
 295                 NULL;
 296
 297         read_lock(&ipip6_lock);
 298
 299         ca = t->prl_count < cmax ? t->prl_count : cmax;
 300
 301         if (!kp) {
 302                 /* We don't try hard to allocate much memory for
 303                  * non-root users.
 304                  * For root users, retry allocating enough memory for
 305                  * the answer.
 306                  */
 307                 kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC);
 308                 if (!kp) {
 309                         ret = -ENOMEM;
 310                         goto out;
 311                 }
 312         }
 313
 314         c = 0;
 315         for (prl = t->prl; prl; prl = prl->next) {
 316                 if (c > cmax)
 317                         break;
 318                 if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
 319                         continue;
 320                 kp[c].addr = prl->addr;
 321                 kp[c].flags = prl->flags;
 322                 kp[c].rs_delay = prl->rs_delay;
 323                 c++;
 324                 if (kprl.addr != htonl(INADDR_ANY))
 325                         break;
 326         }
 327 out:
 328         read_unlock(&ipip6_lock);
 329
 330         len = sizeof(*kp) * c;
 331         ret = 0;
 332         if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
 333                 ret = -EFAULT;
 334
 335         kfree(kp);
 336
 337         return ret;
 338 }
 339
 340 static int
 341 ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
 342 {
 343         struct ip_tunnel_prl_entry *p;
 344         int err = 0;
 345
 346         if (a->addr == htonl(INADDR_ANY))
 347                 return -EINVAL;
 348
 349         write_lock(&ipip6_lock);
 350
 351         for (p = t->prl; p; p = p->next) {
 352                 if (p->addr == a->addr) {
 353                         if (chg)
 354                                 goto update;
 355                         err = -EEXIST;
 356                         goto out;
 357                 }
 358         }
 359
 360         if (chg) {
 361                 err = -ENXIO;
 362                 goto out;
 363         }
 364
 365         p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
 366         if (!p) {
 367                 err = -ENOBUFS;
 368                 goto out;
 369         }
 370
 371         p->next = t->prl;
 372         p->tunnel = t;
 373         t->prl = p;
 374         t->prl_count++;
 375
 376         spin_lock_init(&p->lock);
 377         setup_timer(&p->rs_timer, ipip6_tunnel_rs_timer, (unsigned long) p);
 378 update:
 379         p->addr = a->addr;
 380         p->flags = a->flags;
 381         p->rs_delay = a->rs_delay;
 382         if (p->rs_delay == 0)
 383                 p->rs_delay = IPTUNNEL_RS_DEFAULT_DELAY;
 384         spin_lock(&p->lock);
 385         del_timer(&p->rs_timer);
 386         if (p->flags & PRL_DEFAULT)
 387                 mod_timer(&p->rs_timer, jiffies + 1);
 388         spin_unlock(&p->lock);
 389 out:
 390         write_unlock(&ipip6_lock);
 391         return err;
 392 }
 393
 394 static int
 395 ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
 396 {
 397         struct ip_tunnel_prl_entry *x, **p;
 398         int err = 0;
 399
 400         write_lock(&ipip6_lock);
 401
 402         if (a && a->addr != htonl(INADDR_ANY)) {
 403                 for (p = &t->prl; *p; p = &(*p)->next) {
 404                         if ((*p)->addr == a->addr) {
 405                                 x = *p;
 406                                 *p = x->next;
 407                                 spin_lock(&x->lock);
 408                                 del_timer(&x->rs_timer);
 409                                 spin_unlock(&x->lock);
 410                                 kfree(x);
 411                                 t->prl_count--;
 412                                 goto out;
 413                         }
 414                 }
 415                 err = -ENXIO;
 416         } else {
 417                 while (t->prl) {
 418                         x = t->prl;
 419                         t->prl = t->prl->next;
 420                         spin_lock(&x->lock);
 421                         del_timer(&x->rs_timer);
 422                         spin_unlock(&x->lock);
 423                         kfree(x);
 424                         t->prl_count--;
 425                 }
 426         }
 427 out:
 428         write_unlock(&ipip6_lock);
 429         return err;
 430 }
 431
 432 static int
 433 isatap_chksrc(struct sk_buff *skb, struct iphdr *iph, struct ip_tunnel *t)
 434 {
 435         struct ip_tunnel_prl_entry *p;
 436         int ok = 1;
 437
 438         read_lock(&ipip6_lock);
 439         p = __ipip6_tunnel_locate_prl(t, iph->saddr);
 440         if (p) {
 441                 if (p->flags & PRL_DEFAULT)
 442                         skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
 443                 else
 444                         skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
 445         } else {
 446                 struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
 447                 if (ipv6_addr_is_isatap(addr6) &&
 448                     (addr6->s6_addr32[3] == iph->saddr) &&
 449                     ipv6_chk_prefix(addr6, t->dev))
 450                         skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
 451                 else
 452                         ok = 0;
 453         }
 454         read_unlock(&ipip6_lock);
 455         return ok;
 456 }
 457
 458 static void ipip6_tunnel_uninit(struct net_device *dev)
 459 {
 460         struct net *net = dev_net(dev);
 461         struct sit_net *sitn = net_generic(net, sit_net_id);
 462
 463         if (dev == sitn->fb_tunnel_dev) {
 464                 write_lock_bh(&ipip6_lock);
 465                 sitn->tunnels_wc[0] = NULL;
 466                 write_unlock_bh(&ipip6_lock);
 467                 dev_put(dev);
 468         } else {
 469                 ipip6_tunnel_unlink(sitn, netdev_priv(dev));
 470                 ipip6_tunnel_del_prl(netdev_priv(dev), NULL);
 471                 dev_put(dev);
 472         }
 473 }
 474
 475
 476 static int ipip6_err(struct sk_buff *skb, u32 info)
 477 {
 478
 479 /* All the routers (except for Linux) return only
 480    8 bytes of packet payload. It means, that precise relaying of
 481    ICMP in the real Internet is absolutely infeasible.
 482  */
 483         struct iphdr *iph = (struct iphdr*)skb->data;
 484         const int type = icmp_hdr(skb)->type;
 485         const int code = icmp_hdr(skb)->code;
 486         struct ip_tunnel *t;
 487         int err;
 488
 489         switch (type) {
 490         default:
 491         case ICMP_PARAMETERPROB:
 492                 return 0;
 493
 494         case ICMP_DEST_UNREACH:
 495                 switch (code) {
 496                 case ICMP_SR_FAILED:
 497                 case ICMP_PORT_UNREACH:
 498                         /* Impossible event. */
 499                         return 0;
 500                 case ICMP_FRAG_NEEDED:
 501                         /* Soft state for pmtu is maintained by IP core. */
 502                         return 0;
 503                 default:
 504                         /* All others are translated to HOST_UNREACH.
 505                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 506                            I believe they are just ether pollution. --ANK
 507                          */
 508                         break;
 509                 }
 510                 break;
 511         case ICMP_TIME_EXCEEDED:
 512                 if (code != ICMP_EXC_TTL)
 513                         return 0;
 514                 break;
 515         }
 516
 517         err = -ENOENT;
 518
 519         read_lock(&ipip6_lock);
 520         t = ipip6_tunnel_lookup(dev_net(skb->dev),
 521                                 skb->dev,
 522                                 iph->daddr,
 523                                 iph->saddr);
 524         if (t == NULL || t->parms.iph.daddr == 0)
 525                 goto out;
 526
 527         err = 0;
 528         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 529                 goto out;
 530
 531         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
 532                 t->err_count++;
 533         else
 534                 t->err_count = 1;
 535         t->err_time = jiffies;
 536 out:
 537         read_unlock(&ipip6_lock);
 538         return err;
 539 }
 540
 541 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 542 {
 543         if (INET_ECN_is_ce(iph->tos))
 544                 IP6_ECN_set_ce(ipv6_hdr(skb));
 545 }
 546
 547 static int ipip6_rcv(struct sk_buff *skb)
 548 {
 549         struct iphdr *iph;
 550         struct ip_tunnel *tunnel;
 551
 552         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 553                 goto out;
 554
 555         iph = ip_hdr(skb);
 556
 557         read_lock(&ipip6_lock);
 558         tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
 559                                      iph->saddr, iph->daddr);
 560         if (tunnel != NULL) {
 561                 secpath_reset(skb);
 562                 skb->mac_header = skb->network_header;
 563                 skb_reset_network_header(skb);
 564                 IPCB(skb)->flags = 0;
 565                 skb->protocol = htons(ETH_P_IPV6);
 566                 skb->pkt_type = PACKET_HOST;
 567
 568                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
 569                     !isatap_chksrc(skb, iph, tunnel)) {
 570                         tunnel->dev->stats.rx_errors++;
 571                         read_unlock(&ipip6_lock);
 572                         kfree_skb(skb);
 573                         return 0;
 574                 }
 575                 tunnel->dev->stats.rx_packets++;
 576                 tunnel->dev->stats.rx_bytes += skb->len;
 577                 skb->dev = tunnel->dev;
 578                 skb_dst_drop(skb);
 579                 nf_reset(skb);
 580                 ipip6_ecn_decapsulate(iph, skb);
 581                 netif_rx(skb);
 582                 read_unlock(&ipip6_lock);
 583                 return 0;
 584         }
 585
 586         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 587         read_unlock(&ipip6_lock);
 588 out:
 589         kfree_skb(skb);
 590         return 0;
 591 }
 592
 593 /* Returns the embedded IPv4 address if the IPv6 address
 594    comes from 6to4 (RFC 3056) addr space */
 595
 596 static inline __be32 try_6to4(struct in6_addr *v6dst)
 597 {
 598         __be32 dst = 0;
 599
 600         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 601                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 602                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 603         }
 604         return dst;
 605 }
 606
 607 /*
 608  *      This function assumes it is being called from dev_queue_xmit()
 609  *      and that skb is filled properly by that function.
 610  */
 611
 612 static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 613                                      struct net_device *dev)
 614 {
 615         struct ip_tunnel *tunnel = netdev_priv(dev);
 616         struct net_device_stats *stats = &tunnel->dev->stats;
 617         struct iphdr  *tiph = &tunnel->parms.iph;
 618         struct ipv6hdr *iph6 = ipv6_hdr(skb);
 619         u8     tos = tunnel->parms.iph.tos;
 620         struct rtable *rt;                      /* Route to the other host */
 621         struct net_device *tdev;                        /* Device to other host */
 622         struct iphdr  *iph;                     /* Our new IP header */
 623         unsigned int max_headroom;              /* The extra header space needed */
 624         __be32 dst = tiph->daddr;
 625         int    mtu;
 626         struct in6_addr *addr6;
 627         int addr_type;
 628
 629         if (tunnel->recursion++) {
 630                 stats->collisions++;
 631                 goto tx_error;
 632         }
 633
 634         if (skb->protocol != htons(ETH_P_IPV6))
 635                 goto tx_error;
 636
 637         /* ISATAP (RFC4214) - must come before 6to4 */
 638         if (dev->priv_flags & IFF_ISATAP) {
 639                 struct neighbour *neigh = NULL;
 640
 641                 if (skb_dst(skb))
 642                         neigh = skb_dst(skb)->neighbour;
 643
 644                 if (neigh == NULL) {
 645                         if (net_ratelimit())
 646                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 647                         goto tx_error;
 648                 }
 649
 650                 addr6 = (struct in6_addr*)&neigh->primary_key;
 651                 addr_type = ipv6_addr_type(addr6);
 652
 653                 if ((addr_type & IPV6_ADDR_UNICAST) &&
 654                      ipv6_addr_is_isatap(addr6))
 655                         dst = addr6->s6_addr32[3];
 656                 else
 657                         goto tx_error;
 658         }
 659
 660         if (!dst)
 661                 dst = try_6to4(&iph6->daddr);
 662
 663         if (!dst) {
 664                 struct neighbour *neigh = NULL;
 665
 666                 if (skb_dst(skb))
 667                         neigh = skb_dst(skb)->neighbour;
 668
 669                 if (neigh == NULL) {
 670                         if (net_ratelimit())
 671                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 672                         goto tx_error;
 673                 }
 674
 675                 addr6 = (struct in6_addr*)&neigh->primary_key;
 676                 addr_type = ipv6_addr_type(addr6);
 677
 678                 if (addr_type == IPV6_ADDR_ANY) {
 679                         addr6 = &ipv6_hdr(skb)->daddr;
 680                         addr_type = ipv6_addr_type(addr6);
 681                 }
 682
 683                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 684                         goto tx_error_icmp;
 685
 686                 dst = addr6->s6_addr32[3];
 687         }
 688
 689         {
 690                 struct flowi fl = { .nl_u = { .ip4_u =
 691                                               { .daddr = dst,
 692                                                 .saddr = tiph->saddr,
 693                                                 .tos = RT_TOS(tos) } },
 694                                     .oif = tunnel->parms.link,
 695                                     .proto = IPPROTO_IPV6 };
 696                 if (ip_route_output_key(dev_net(dev), &rt, &fl)) {
 697                         stats->tx_carrier_errors++;
 698                         goto tx_error_icmp;
 699                 }
 700         }
 701         if (rt->rt_type != RTN_UNICAST) {
 702                 ip_rt_put(rt);
 703                 stats->tx_carrier_errors++;
 704                 goto tx_error_icmp;
 705         }
 706         tdev = rt->u.dst.dev;
 707
 708         if (tdev == dev) {
 709                 ip_rt_put(rt);
 710                 stats->collisions++;
 711                 goto tx_error;
 712         }
 713
 714         if (tiph->frag_off)
 715                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 716         else
 717                 mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
 718
 719         if (mtu < 68) {
 720                 stats->collisions++;
 721                 ip_rt_put(rt);
 722                 goto tx_error;
 723         }
 724         if (mtu < IPV6_MIN_MTU)
 725                 mtu = IPV6_MIN_MTU;
 726         if (tunnel->parms.iph.daddr && skb_dst(skb))
 727                 skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 728
 729         if (skb->len > mtu) {
 730                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 731                 ip_rt_put(rt);
 732                 goto tx_error;
 733         }
 734
 735         if (tunnel->err_count > 0) {
 736                 if (time_before(jiffies,
 737                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
 738                         tunnel->err_count--;
 739                         dst_link_failure(skb);
 740                 } else
 741                         tunnel->err_count = 0;
 742         }
 743
 744         /*
 745          * Okay, now see if we can stuff it in the buffer as-is.
 746          */
 747         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 748
 749         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 750             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 751                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 752                 if (!new_skb) {
 753                         ip_rt_put(rt);
 754                         stats->tx_dropped++;
 755                         dev_kfree_skb(skb);
 756                         tunnel->recursion--;
 757                         return NETDEV_TX_OK;
 758                 }
 759                 if (skb->sk)
 760                         skb_set_owner_w(new_skb, skb->sk);
 761                 dev_kfree_skb(skb);
 762                 skb = new_skb;
 763                 iph6 = ipv6_hdr(skb);
 764         }
 765
 766         skb->transport_header = skb->network_header;
 767         skb_push(skb, sizeof(struct iphdr));
 768         skb_reset_network_header(skb);
 769         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 770         IPCB(skb)->flags = 0;
 771         skb_dst_drop(skb);
 772         skb_dst_set(skb, &rt->u.dst);
 773
 774         /*
 775          *      Push down and install the IPIP header.
 776          */
 777
 778         iph                     =       ip_hdr(skb);
 779         iph->version            =       4;
 780         iph->ihl                =       sizeof(struct iphdr)>>2;
 781         if (mtu > IPV6_MIN_MTU)
 782                 iph->frag_off   =       tiph->frag_off;
 783         else
 784                 iph->frag_off   =       0;
 785
 786         iph->protocol           =       IPPROTO_IPV6;
 787         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 788         iph->daddr              =       rt->rt_dst;
 789         iph->saddr              =       rt->rt_src;
 790
 791         if ((iph->ttl = tiph->ttl) == 0)
 792                 iph->ttl        =       iph6->hop_limit;
 793
 794         nf_reset(skb);
 795
 796         IPTUNNEL_XMIT();
 797         tunnel->recursion--;
 798         return NETDEV_TX_OK;
 799
 800 tx_error_icmp:
 801         dst_link_failure(skb);
 802 tx_error:
 803         stats->tx_errors++;
 804         dev_kfree_skb(skb);
 805         tunnel->recursion--;
 806         return NETDEV_TX_OK;
 807 }
 808
 809 static void ipip6_tunnel_bind_dev(struct net_device *dev)
 810 {
 811         struct net_device *tdev = NULL;
 812         struct ip_tunnel *tunnel;
 813         struct iphdr *iph;
 814
 815         tunnel = netdev_priv(dev);
 816         iph = &tunnel->parms.iph;
 817
 818         if (iph->daddr) {
 819                 struct flowi fl = { .nl_u = { .ip4_u =
 820                                               { .daddr = iph->daddr,
 821                                                 .saddr = iph->saddr,
 822                                                 .tos = RT_TOS(iph->tos) } },
 823                                     .oif = tunnel->parms.link,
 824                                     .proto = IPPROTO_IPV6 };
 825                 struct rtable *rt;
 826                 if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 827                         tdev = rt->u.dst.dev;
 828                         ip_rt_put(rt);
 829                 }
 830                 dev->flags |= IFF_POINTOPOINT;
 831         }
 832
 833         if (!tdev && tunnel->parms.link)
 834                 tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);
 835
 836         if (tdev) {
 837                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 838                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 839                 if (dev->mtu < IPV6_MIN_MTU)
 840                         dev->mtu = IPV6_MIN_MTU;
 841         }
 842         dev->iflink = tunnel->parms.link;
 843 }
 844
 845 static int
 846 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 847 {
 848         int err = 0;
 849         struct ip_tunnel_parm p;
 850         struct ip_tunnel_prl prl;
 851         struct ip_tunnel *t;
 852         struct net *net = dev_net(dev);
 853         struct sit_net *sitn = net_generic(net, sit_net_id);
 854
 855         switch (cmd) {
 856         case SIOCGETTUNNEL:
 857                 t = NULL;
 858                 if (dev == sitn->fb_tunnel_dev) {
 859                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 860                                 err = -EFAULT;
 861                                 break;
 862                         }
 863                         t = ipip6_tunnel_locate(net, &p, 0);
 864                 }
 865                 if (t == NULL)
 866                         t = netdev_priv(dev);
 867                 memcpy(&p, &t->parms, sizeof(p));
 868                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 869                         err = -EFAULT;
 870                 break;
 871
 872         case SIOCADDTUNNEL:
 873         case SIOCCHGTUNNEL:
 874                 err = -EPERM;
 875                 if (!capable(CAP_NET_ADMIN))
 876                         goto done;
 877
 878                 err = -EFAULT;
 879                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 880                         goto done;
 881
 882                 err = -EINVAL;
 883                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 884                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 885                         goto done;
 886                 if (p.iph.ttl)
 887                         p.iph.frag_off |= htons(IP_DF);
 888
 889                 t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
 890
 891                 if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 892                         if (t != NULL) {
 893                                 if (t->dev != dev) {
 894                                         err = -EEXIST;
 895                                         break;
 896                                 }
 897                         } else {
 898                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 899                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 900                                         err = -EINVAL;
 901                                         break;
 902                                 }
 903                                 t = netdev_priv(dev);
 904                                 ipip6_tunnel_unlink(sitn, t);
 905                                 t->parms.iph.saddr = p.iph.saddr;
 906                                 t->parms.iph.daddr = p.iph.daddr;
 907                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 908                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 909                                 ipip6_tunnel_link(sitn, t);
 910                                 netdev_state_change(dev);
 911                         }
 912                 }
 913
 914                 if (t) {
 915                         err = 0;
 916                         if (cmd == SIOCCHGTUNNEL) {
 917                                 t->parms.iph.ttl = p.iph.ttl;
 918                                 t->parms.iph.tos = p.iph.tos;
 919                                 if (t->parms.link != p.link) {
 920                                         t->parms.link = p.link;
 921                                         ipip6_tunnel_bind_dev(dev);
 922                                         netdev_state_change(dev);
 923                                 }
 924                         }
 925                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 926                                 err = -EFAULT;
 927                 } else
 928                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 929                 break;
 930
 931         case SIOCDELTUNNEL:
 932                 err = -EPERM;
 933                 if (!capable(CAP_NET_ADMIN))
 934                         goto done;
 935
 936                 if (dev == sitn->fb_tunnel_dev) {
 937                         err = -EFAULT;
 938                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 939                                 goto done;
 940                         err = -ENOENT;
 941                         if ((t = ipip6_tunnel_locate(net, &p, 0)) == NULL)
 942                                 goto done;
 943                         err = -EPERM;
 944                         if (t == netdev_priv(sitn->fb_tunnel_dev))
 945                                 goto done;
 946                         dev = t->dev;
 947                 }
 948                 unregister_netdevice(dev);
 949                 err = 0;
 950                 break;
 951
 952         case SIOCGETPRL:
 953                 err = -EINVAL;
 954                 if (dev == sitn->fb_tunnel_dev)
 955                         goto done;
 956                 err = -ENOENT;
 957                 if (!(t = netdev_priv(dev)))
 958                         goto done;
 959                 err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
 960                 break;
 961
 962         case SIOCADDPRL:
 963         case SIOCDELPRL:
 964         case SIOCCHGPRL:
 965                 err = -EPERM;
 966                 if (!capable(CAP_NET_ADMIN))
 967                         goto done;
 968                 err = -EINVAL;
 969                 if (dev == sitn->fb_tunnel_dev)
 970                         goto done;
 971                 err = -EFAULT;
 972                 if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
 973                         goto done;
 974                 err = -ENOENT;
 975                 if (!(t = netdev_priv(dev)))
 976                         goto done;
 977
 978                 switch (cmd) {
 979                 case SIOCDELPRL:
 980                         err = ipip6_tunnel_del_prl(t, &prl);
 981                         break;
 982                 case SIOCADDPRL:
 983                 case SIOCCHGPRL:
 984                         err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
 985                         break;
 986                 }
 987                 netdev_state_change(dev);
 988                 break;
 989
 990         default:
 991                 err = -EINVAL;
 992         }
 993
 994 done:
 995         return err;
 996 }
 997
 998 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
 999 {
1000         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
1001                 return -EINVAL;
1002         dev->mtu = new_mtu;
1003         return 0;
1004 }
1005
1006 static const struct net_device_ops ipip6_netdev_ops = {
1007         .ndo_uninit     = ipip6_tunnel_uninit,
1008         .ndo_start_xmit = ipip6_tunnel_xmit,
1009         .ndo_do_ioctl   = ipip6_tunnel_ioctl,
1010         .ndo_change_mtu = ipip6_tunnel_change_mtu,
1011 };
1012
1013 static void ipip6_tunnel_setup(struct net_device *dev)
1014 {
1015         dev->netdev_ops         = &ipip6_netdev_ops;
1016         dev->destructor         = free_netdev;
1017
1018         dev->type               = ARPHRD_SIT;
1019         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
1020         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
1021         dev->flags              = IFF_NOARP;
1022         dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
1023         dev->iflink             = 0;
1024         dev->addr_len           = 4;
1025         dev->features           |= NETIF_F_NETNS_LOCAL;
1026 }
1027
1028 static void ipip6_tunnel_init(struct net_device *dev)
1029 {
1030         struct ip_tunnel *tunnel = netdev_priv(dev);
1031
1032         tunnel->dev = dev;
1033         strcpy(tunnel->parms.name, dev->name);
1034
1035         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1036         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1037
1038         ipip6_tunnel_bind_dev(dev);
1039 }
1040
1041 static void ipip6_fb_tunnel_init(struct net_device *dev)
1042 {
1043         struct ip_tunnel *tunnel = netdev_priv(dev);
1044         struct iphdr *iph = &tunnel->parms.iph;
1045         struct net *net = dev_net(dev);
1046         struct sit_net *sitn = net_generic(net, sit_net_id);
1047
1048         tunnel->dev = dev;
1049         strcpy(tunnel->parms.name, dev->name);
1050
1051         iph->version            = 4;
1052         iph->protocol           = IPPROTO_IPV6;
1053         iph->ihl                = 5;
1054         iph->ttl                = 64;
1055
1056         dev_hold(dev);
1057         sitn->tunnels_wc[0]     = tunnel;
1058 }
1059
1060 static struct xfrm_tunnel sit_handler = {
1061         .handler        =       ipip6_rcv,
1062         .err_handler    =       ipip6_err,
1063         .priority       =       1,
1064 };
1065
1066 static void sit_destroy_tunnels(struct sit_net *sitn)
1067 {
1068         int prio;
1069
1070         for (prio = 1; prio < 4; prio++) {
1071                 int h;
1072                 for (h = 0; h < HASH_SIZE; h++) {
1073                         struct ip_tunnel *t;
1074                         while ((t = sitn->tunnels[prio][h]) != NULL)
1075                                 unregister_netdevice(t->dev);
1076                 }
1077         }
1078 }
1079
1080 static int sit_init_net(struct net *net)
1081 {
1082         int err;
1083         struct sit_net *sitn;
1084
1085         err = -ENOMEM;
1086         sitn = kzalloc(sizeof(struct sit_net), GFP_KERNEL);
1087         if (sitn == NULL)
1088                 goto err_alloc;
1089
1090         err = net_assign_generic(net, sit_net_id, sitn);
1091         if (err < 0)
1092                 goto err_assign;
1093
1094         sitn->tunnels[0] = sitn->tunnels_wc;
1095         sitn->tunnels[1] = sitn->tunnels_l;
1096         sitn->tunnels[2] = sitn->tunnels_r;
1097         sitn->tunnels[3] = sitn->tunnels_r_l;
1098
1099         sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
1100                                            ipip6_tunnel_setup);
1101         if (!sitn->fb_tunnel_dev) {
1102                 err = -ENOMEM;
1103                 goto err_alloc_dev;
1104         }
1105         dev_net_set(sitn->fb_tunnel_dev, net);
1106
1107         ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
1108
1109         if ((err = register_netdev(sitn->fb_tunnel_dev)))
1110                 goto err_reg_dev;
1111
1112         return 0;
1113
1114 err_reg_dev:
1115         dev_put(sitn->fb_tunnel_dev);
1116         free_netdev(sitn->fb_tunnel_dev);
1117 err_alloc_dev:
1118         /* nothing */
1119 err_assign:
1120         kfree(sitn);
1121 err_alloc:
1122         return err;
1123 }
1124
1125 static void sit_exit_net(struct net *net)
1126 {
1127         struct sit_net *sitn;
1128
1129         sitn = net_generic(net, sit_net_id);
1130         rtnl_lock();
1131         sit_destroy_tunnels(sitn);
1132         unregister_netdevice(sitn->fb_tunnel_dev);
1133         rtnl_unlock();
1134         kfree(sitn);
1135 }
1136
1137 static struct pernet_operations sit_net_ops = {
1138         .init = sit_init_net,
1139         .exit = sit_exit_net,
1140 };
1141
1142 static void __exit sit_cleanup(void)
1143 {
1144         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1145
1146         unregister_pernet_gen_device(sit_net_id, &sit_net_ops);
1147 }
1148
1149 static int __init sit_init(void)
1150 {
1151         int err;
1152
1153         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
1154
1155         if (xfrm4_tunnel_register(&sit_handler, AF_INET6) < 0) {
1156                 printk(KERN_INFO "sit init: Can't add protocol\n");
1157                 return -EAGAIN;
1158         }
1159
1160         err = register_pernet_gen_device(&sit_net_id, &sit_net_ops);
1161         if (err < 0)
1162                 xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1163
1164         return err;
1165 }
1166
1167 module_init(sit_init);
1168 module_exit(sit_cleanup);
1169 MODULE_LICENSE("GPL");
1170 MODULE_ALIAS("sit0");