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   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  *      $Id: sit.c,v 1.53 2001/09/25 05:09:53 davem Exp $
  10  *
  11  *      This program is free software; you can redistribute it and/or
  12  *      modify it under the terms of the GNU General Public License
  13  *      as published by the Free Software Foundation; either version
  14  *      2 of the License, or (at your option) any later version.
  15  *
  16  *      Changes:
  17  * Roger Venning <r.venning@telstra.com>:       6to4 support
  18  * Nate Thompson <nate@thebog.net>:             6to4 support
  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/sched.h>
  28 #include <linux/net.h>
  29 #include <linux/in6.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/if_arp.h>
  32 #include <linux/icmp.h>
  33 #include <asm/uaccess.h>
  34 #include <linux/init.h>
  35 #include <linux/netfilter_ipv4.h>
  36 #include <linux/if_ether.h>
  37
  38 #include <net/sock.h>
  39 #include <net/snmp.h>
  40
  41 #include <net/ipv6.h>
  42 #include <net/protocol.h>
  43 #include <net/transp_v6.h>
  44 #include <net/ip6_fib.h>
  45 #include <net/ip6_route.h>
  46 #include <net/ndisc.h>
  47 #include <net/addrconf.h>
  48 #include <net/ip.h>
  49 #include <net/udp.h>
  50 #include <net/icmp.h>
  51 #include <net/ipip.h>
  52 #include <net/inet_ecn.h>
  53 #include <net/xfrm.h>
  54 #include <net/dsfield.h>
  55
  56 /*
  57    This version of net/ipv6/sit.c is cloned of net/ipv4/ip_gre.c
  58
  59    For comments look at net/ipv4/ip_gre.c --ANK
  60  */
  61
  62 #define HASH_SIZE  16
  63 #define HASH(addr) ((addr^(addr>>4))&0xF)
  64
  65 static int ipip6_fb_tunnel_init(struct net_device *dev);
  66 static int ipip6_tunnel_init(struct net_device *dev);
  67 static void ipip6_tunnel_setup(struct net_device *dev);
  68
  69 static struct net_device *ipip6_fb_tunnel_dev;
  70
  71 static struct ip_tunnel *tunnels_r_l[HASH_SIZE];
  72 static struct ip_tunnel *tunnels_r[HASH_SIZE];
  73 static struct ip_tunnel *tunnels_l[HASH_SIZE];
  74 static struct ip_tunnel *tunnels_wc[1];
  75 static struct ip_tunnel **tunnels[4] = { tunnels_wc, tunnels_l, tunnels_r, tunnels_r_l };
  76
  77 static DEFINE_RWLOCK(ipip6_lock);
  78
  79 static struct ip_tunnel * ipip6_tunnel_lookup(u32 remote, u32 local)
  80 {
  81         unsigned h0 = HASH(remote);
  82         unsigned h1 = HASH(local);
  83         struct ip_tunnel *t;
  84
  85         for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
  86                 if (local == t->parms.iph.saddr &&
  87                     remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
  88                         return t;
  89         }
  90         for (t = tunnels_r[h0]; t; t = t->next) {
  91                 if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
  92                         return t;
  93         }
  94         for (t = tunnels_l[h1]; t; t = t->next) {
  95                 if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
  96                         return t;
  97         }
  98         if ((t = tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP))
  99                 return t;
 100         return NULL;
 101 }
 102
 103 static struct ip_tunnel ** ipip6_bucket(struct ip_tunnel *t)
 104 {
 105         u32 remote = t->parms.iph.daddr;
 106         u32 local = t->parms.iph.saddr;
 107         unsigned h = 0;
 108         int prio = 0;
 109
 110         if (remote) {
 111                 prio |= 2;
 112                 h ^= HASH(remote);
 113         }
 114         if (local) {
 115                 prio |= 1;
 116                 h ^= HASH(local);
 117         }
 118         return &tunnels[prio][h];
 119 }
 120
 121 static void ipip6_tunnel_unlink(struct ip_tunnel *t)
 122 {
 123         struct ip_tunnel **tp;
 124
 125         for (tp = ipip6_bucket(t); *tp; tp = &(*tp)->next) {
 126                 if (t == *tp) {
 127                         write_lock_bh(&ipip6_lock);
 128                         *tp = t->next;
 129                         write_unlock_bh(&ipip6_lock);
 130                         break;
 131                 }
 132         }
 133 }
 134
 135 static void ipip6_tunnel_link(struct ip_tunnel *t)
 136 {
 137         struct ip_tunnel **tp = ipip6_bucket(t);
 138
 139         t->next = *tp;
 140         write_lock_bh(&ipip6_lock);
 141         *tp = t;
 142         write_unlock_bh(&ipip6_lock);
 143 }
 144
 145 static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create)
 146 {
 147         u32 remote = parms->iph.daddr;
 148         u32 local = parms->iph.saddr;
 149         struct ip_tunnel *t, **tp, *nt;
 150         struct net_device *dev;
 151         unsigned h = 0;
 152         int prio = 0;
 153         char name[IFNAMSIZ];
 154
 155         if (remote) {
 156                 prio |= 2;
 157                 h ^= HASH(remote);
 158         }
 159         if (local) {
 160                 prio |= 1;
 161                 h ^= HASH(local);
 162         }
 163         for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
 164                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
 165                         return t;
 166         }
 167         if (!create)
 168                 goto failed;
 169
 170         if (parms->name[0])
 171                 strlcpy(name, parms->name, IFNAMSIZ);
 172         else {
 173                 int i;
 174                 for (i=1; i<100; i++) {
 175                         sprintf(name, "sit%d", i);
 176                         if (__dev_get_by_name(name) == NULL)
 177                                 break;
 178                 }
 179                 if (i==100)
 180                         goto failed;
 181         }
 182
 183         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
 184         if (dev == NULL)
 185                 return NULL;
 186
 187         nt = netdev_priv(dev);
 188         dev->init = ipip6_tunnel_init;
 189         nt->parms = *parms;
 190
 191         if (register_netdevice(dev) < 0) {
 192                 free_netdev(dev);
 193                 goto failed;
 194         }
 195
 196         dev_hold(dev);
 197
 198         ipip6_tunnel_link(nt);
 199         return nt;
 200
 201 failed:
 202         return NULL;
 203 }
 204
 205 static void ipip6_tunnel_uninit(struct net_device *dev)
 206 {
 207         if (dev == ipip6_fb_tunnel_dev) {
 208                 write_lock_bh(&ipip6_lock);
 209                 tunnels_wc[0] = NULL;
 210                 write_unlock_bh(&ipip6_lock);
 211                 dev_put(dev);
 212         } else {
 213                 ipip6_tunnel_unlink(netdev_priv(dev));
 214                 dev_put(dev);
 215         }
 216 }
 217
 218
 219 static void ipip6_err(struct sk_buff *skb, u32 info)
 220 {
 221 #ifndef I_WISH_WORLD_WERE_PERFECT
 222
 223 /* It is not :-( All the routers (except for Linux) return only
 224    8 bytes of packet payload. It means, that precise relaying of
 225    ICMP in the real Internet is absolutely infeasible.
 226  */
 227         struct iphdr *iph = (struct iphdr*)skb->data;
 228         int type = skb->h.icmph->type;
 229         int code = skb->h.icmph->code;
 230         struct ip_tunnel *t;
 231
 232         switch (type) {
 233         default:
 234         case ICMP_PARAMETERPROB:
 235                 return;
 236
 237         case ICMP_DEST_UNREACH:
 238                 switch (code) {
 239                 case ICMP_SR_FAILED:
 240                 case ICMP_PORT_UNREACH:
 241                         /* Impossible event. */
 242                         return;
 243                 case ICMP_FRAG_NEEDED:
 244                         /* Soft state for pmtu is maintained by IP core. */
 245                         return;
 246                 default:
 247                         /* All others are translated to HOST_UNREACH.
 248                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 249                            I believe they are just ether pollution. --ANK
 250                          */
 251                         break;
 252                 }
 253                 break;
 254         case ICMP_TIME_EXCEEDED:
 255                 if (code != ICMP_EXC_TTL)
 256                         return;
 257                 break;
 258         }
 259
 260         read_lock(&ipip6_lock);
 261         t = ipip6_tunnel_lookup(iph->daddr, iph->saddr);
 262         if (t == NULL || t->parms.iph.daddr == 0)
 263                 goto out;
 264         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 265                 goto out;
 266
 267         if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
 268                 t->err_count++;
 269         else
 270                 t->err_count = 1;
 271         t->err_time = jiffies;
 272 out:
 273         read_unlock(&ipip6_lock);
 274         return;
 275 #else
 276         struct iphdr *iph = (struct iphdr*)dp;
 277         int hlen = iph->ihl<<2;
 278         struct ipv6hdr *iph6;
 279         int type = skb->h.icmph->type;
 280         int code = skb->h.icmph->code;
 281         int rel_type = 0;
 282         int rel_code = 0;
 283         int rel_info = 0;
 284         struct sk_buff *skb2;
 285         struct rt6_info *rt6i;
 286
 287         if (len < hlen + sizeof(struct ipv6hdr))
 288                 return;
 289         iph6 = (struct ipv6hdr*)(dp + hlen);
 290
 291         switch (type) {
 292         default:
 293                 return;
 294         case ICMP_PARAMETERPROB:
 295                 if (skb->h.icmph->un.gateway < hlen)
 296                         return;
 297
 298                 /* So... This guy found something strange INSIDE encapsulated
 299                    packet. Well, he is fool, but what can we do ?
 300                  */
 301                 rel_type = ICMPV6_PARAMPROB;
 302                 rel_info = skb->h.icmph->un.gateway - hlen;
 303                 break;
 304
 305         case ICMP_DEST_UNREACH:
 306                 switch (code) {
 307                 case ICMP_SR_FAILED:
 308                 case ICMP_PORT_UNREACH:
 309                         /* Impossible event. */
 310                         return;
 311                 case ICMP_FRAG_NEEDED:
 312                         /* Too complicated case ... */
 313                         return;
 314                 default:
 315                         /* All others are translated to HOST_UNREACH.
 316                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 317                            I believe, it is just ether pollution. --ANK
 318                          */
 319                         rel_type = ICMPV6_DEST_UNREACH;
 320                         rel_code = ICMPV6_ADDR_UNREACH;
 321                         break;
 322                 }
 323                 break;
 324         case ICMP_TIME_EXCEEDED:
 325                 if (code != ICMP_EXC_TTL)
 326                         return;
 327                 rel_type = ICMPV6_TIME_EXCEED;
 328                 rel_code = ICMPV6_EXC_HOPLIMIT;
 329                 break;
 330         }
 331
 332         /* Prepare fake skb to feed it to icmpv6_send */
 333         skb2 = skb_clone(skb, GFP_ATOMIC);
 334         if (skb2 == NULL)
 335                 return;
 336         dst_release(skb2->dst);
 337         skb2->dst = NULL;
 338         skb_pull(skb2, skb->data - (u8*)iph6);
 339         skb2->nh.raw = skb2->data;
 340
 341         /* Try to guess incoming interface */
 342         rt6i = rt6_lookup(&iph6->saddr, NULL, NULL, 0);
 343         if (rt6i && rt6i->rt6i_dev) {
 344                 skb2->dev = rt6i->rt6i_dev;
 345
 346                 rt6i = rt6_lookup(&iph6->daddr, &iph6->saddr, NULL, 0);
 347
 348                 if (rt6i && rt6i->rt6i_dev && rt6i->rt6i_dev->type == ARPHRD_SIT) {
 349                         struct ip_tunnel *t = netdev_priv(rt6i->rt6i_dev);
 350                         if (rel_type == ICMPV6_TIME_EXCEED && t->parms.iph.ttl) {
 351                                 rel_type = ICMPV6_DEST_UNREACH;
 352                                 rel_code = ICMPV6_ADDR_UNREACH;
 353                         }
 354                         icmpv6_send(skb2, rel_type, rel_code, rel_info, skb2->dev);
 355                 }
 356         }
 357         kfree_skb(skb2);
 358         return;
 359 #endif
 360 }
 361
 362 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 363 {
 364         if (INET_ECN_is_ce(iph->tos))
 365                 IP6_ECN_set_ce(skb->nh.ipv6h);
 366 }
 367
 368 static int ipip6_rcv(struct sk_buff *skb)
 369 {
 370         struct iphdr *iph;
 371         struct ip_tunnel *tunnel;
 372
 373         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 374                 goto out;
 375
 376         iph = skb->nh.iph;
 377
 378         read_lock(&ipip6_lock);
 379         if ((tunnel = ipip6_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
 380                 secpath_reset(skb);
 381                 skb->mac.raw = skb->nh.raw;
 382                 skb->nh.raw = skb->data;
 383                 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 384                 IPCB(skb)->flags = 0;
 385                 skb->protocol = htons(ETH_P_IPV6);
 386                 skb->pkt_type = PACKET_HOST;
 387                 tunnel->stat.rx_packets++;
 388                 tunnel->stat.rx_bytes += skb->len;
 389                 skb->dev = tunnel->dev;
 390                 dst_release(skb->dst);
 391                 skb->dst = NULL;
 392                 nf_reset(skb);
 393                 ipip6_ecn_decapsulate(iph, skb);
 394                 netif_rx(skb);
 395                 read_unlock(&ipip6_lock);
 396                 return 0;
 397         }
 398
 399         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 400         kfree_skb(skb);
 401         read_unlock(&ipip6_lock);
 402 out:
 403         return 0;
 404 }
 405
 406 /* Returns the embedded IPv4 address if the IPv6 address
 407    comes from 6to4 (RFC 3056) addr space */
 408
 409 static inline u32 try_6to4(struct in6_addr *v6dst)
 410 {
 411         u32 dst = 0;
 412
 413         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 414                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 415                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 416         }
 417         return dst;
 418 }
 419
 420 /*
 421  *      This function assumes it is being called from dev_queue_xmit()
 422  *      and that skb is filled properly by that function.
 423  */
 424
 425 static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 426 {
 427         struct ip_tunnel *tunnel = netdev_priv(dev);
 428         struct net_device_stats *stats = &tunnel->stat;
 429         struct iphdr  *tiph = &tunnel->parms.iph;
 430         struct ipv6hdr *iph6 = skb->nh.ipv6h;
 431         u8     tos = tunnel->parms.iph.tos;
 432         struct rtable *rt;                      /* Route to the other host */
 433         struct net_device *tdev;                        /* Device to other host */
 434         struct iphdr  *iph;                     /* Our new IP header */
 435         int    max_headroom;                    /* The extra header space needed */
 436         u32    dst = tiph->daddr;
 437         int    mtu;
 438         struct in6_addr *addr6;
 439         int addr_type;
 440
 441         if (tunnel->recursion++) {
 442                 tunnel->stat.collisions++;
 443                 goto tx_error;
 444         }
 445
 446         if (skb->protocol != htons(ETH_P_IPV6))
 447                 goto tx_error;
 448
 449         if (!dst)
 450                 dst = try_6to4(&iph6->daddr);
 451
 452         if (!dst) {
 453                 struct neighbour *neigh = NULL;
 454
 455                 if (skb->dst)
 456                         neigh = skb->dst->neighbour;
 457
 458                 if (neigh == NULL) {
 459                         if (net_ratelimit())
 460                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 461                         goto tx_error;
 462                 }
 463
 464                 addr6 = (struct in6_addr*)&neigh->primary_key;
 465                 addr_type = ipv6_addr_type(addr6);
 466
 467                 if (addr_type == IPV6_ADDR_ANY) {
 468                         addr6 = &skb->nh.ipv6h->daddr;
 469                         addr_type = ipv6_addr_type(addr6);
 470                 }
 471
 472                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 473                         goto tx_error_icmp;
 474
 475                 dst = addr6->s6_addr32[3];
 476         }
 477
 478         {
 479                 struct flowi fl = { .nl_u = { .ip4_u =
 480                                               { .daddr = dst,
 481                                                 .saddr = tiph->saddr,
 482                                                 .tos = RT_TOS(tos) } },
 483                                     .oif = tunnel->parms.link,
 484                                     .proto = IPPROTO_IPV6 };
 485                 if (ip_route_output_key(&rt, &fl)) {
 486                         tunnel->stat.tx_carrier_errors++;
 487                         goto tx_error_icmp;
 488                 }
 489         }
 490         if (rt->rt_type != RTN_UNICAST) {
 491                 ip_rt_put(rt);
 492                 tunnel->stat.tx_carrier_errors++;
 493                 goto tx_error_icmp;
 494         }
 495         tdev = rt->u.dst.dev;
 496
 497         if (tdev == dev) {
 498                 ip_rt_put(rt);
 499                 tunnel->stat.collisions++;
 500                 goto tx_error;
 501         }
 502
 503         if (tiph->frag_off)
 504                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 505         else
 506                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 507
 508         if (mtu < 68) {
 509                 tunnel->stat.collisions++;
 510                 ip_rt_put(rt);
 511                 goto tx_error;
 512         }
 513         if (mtu < IPV6_MIN_MTU)
 514                 mtu = IPV6_MIN_MTU;
 515         if (tunnel->parms.iph.daddr && skb->dst)
 516                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 517
 518         if (skb->len > mtu) {
 519                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 520                 ip_rt_put(rt);
 521                 goto tx_error;
 522         }
 523
 524         if (tunnel->err_count > 0) {
 525                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 526                         tunnel->err_count--;
 527                         dst_link_failure(skb);
 528                 } else
 529                         tunnel->err_count = 0;
 530         }
 531
 532         /*
 533          * Okay, now see if we can stuff it in the buffer as-is.
 534          */
 535         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 536
 537         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 538                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 539                 if (!new_skb) {
 540                         ip_rt_put(rt);
 541                         stats->tx_dropped++;
 542                         dev_kfree_skb(skb);
 543                         tunnel->recursion--;
 544                         return 0;
 545                 }
 546                 if (skb->sk)
 547                         skb_set_owner_w(new_skb, skb->sk);
 548                 dev_kfree_skb(skb);
 549                 skb = new_skb;
 550                 iph6 = skb->nh.ipv6h;
 551         }
 552
 553         skb->h.raw = skb->nh.raw;
 554         skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
 555         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 556         IPCB(skb)->flags = 0;
 557         dst_release(skb->dst);
 558         skb->dst = &rt->u.dst;
 559
 560         /*
 561          *      Push down and install the IPIP header.
 562          */
 563
 564         iph                     =       skb->nh.iph;
 565         iph->version            =       4;
 566         iph->ihl                =       sizeof(struct iphdr)>>2;
 567         if (mtu > IPV6_MIN_MTU)
 568                 iph->frag_off   =       htons(IP_DF);
 569         else
 570                 iph->frag_off   =       0;
 571
 572         iph->protocol           =       IPPROTO_IPV6;
 573         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 574         iph->daddr              =       rt->rt_dst;
 575         iph->saddr              =       rt->rt_src;
 576
 577         if ((iph->ttl = tiph->ttl) == 0)
 578                 iph->ttl        =       iph6->hop_limit;
 579
 580         nf_reset(skb);
 581
 582         IPTUNNEL_XMIT();
 583         tunnel->recursion--;
 584         return 0;
 585
 586 tx_error_icmp:
 587         dst_link_failure(skb);
 588 tx_error:
 589         stats->tx_errors++;
 590         dev_kfree_skb(skb);
 591         tunnel->recursion--;
 592         return 0;
 593 }
 594
 595 static int
 596 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 597 {
 598         int err = 0;
 599         struct ip_tunnel_parm p;
 600         struct ip_tunnel *t;
 601
 602         switch (cmd) {
 603         case SIOCGETTUNNEL:
 604                 t = NULL;
 605                 if (dev == ipip6_fb_tunnel_dev) {
 606                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 607                                 err = -EFAULT;
 608                                 break;
 609                         }
 610                         t = ipip6_tunnel_locate(&p, 0);
 611                 }
 612                 if (t == NULL)
 613                         t = netdev_priv(dev);
 614                 memcpy(&p, &t->parms, sizeof(p));
 615                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 616                         err = -EFAULT;
 617                 break;
 618
 619         case SIOCADDTUNNEL:
 620         case SIOCCHGTUNNEL:
 621                 err = -EPERM;
 622                 if (!capable(CAP_NET_ADMIN))
 623                         goto done;
 624
 625                 err = -EFAULT;
 626                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 627                         goto done;
 628
 629                 err = -EINVAL;
 630                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 631                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 632                         goto done;
 633                 if (p.iph.ttl)
 634                         p.iph.frag_off |= htons(IP_DF);
 635
 636                 t = ipip6_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 637
 638                 if (dev != ipip6_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 639                         if (t != NULL) {
 640                                 if (t->dev != dev) {
 641                                         err = -EEXIST;
 642                                         break;
 643                                 }
 644                         } else {
 645                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 646                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 647                                         err = -EINVAL;
 648                                         break;
 649                                 }
 650                                 t = netdev_priv(dev);
 651                                 ipip6_tunnel_unlink(t);
 652                                 t->parms.iph.saddr = p.iph.saddr;
 653                                 t->parms.iph.daddr = p.iph.daddr;
 654                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 655                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 656                                 ipip6_tunnel_link(t);
 657                                 netdev_state_change(dev);
 658                         }
 659                 }
 660
 661                 if (t) {
 662                         err = 0;
 663                         if (cmd == SIOCCHGTUNNEL) {
 664                                 t->parms.iph.ttl = p.iph.ttl;
 665                                 t->parms.iph.tos = p.iph.tos;
 666                         }
 667                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 668                                 err = -EFAULT;
 669                 } else
 670                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 671                 break;
 672
 673         case SIOCDELTUNNEL:
 674                 err = -EPERM;
 675                 if (!capable(CAP_NET_ADMIN))
 676                         goto done;
 677
 678                 if (dev == ipip6_fb_tunnel_dev) {
 679                         err = -EFAULT;
 680                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 681                                 goto done;
 682                         err = -ENOENT;
 683                         if ((t = ipip6_tunnel_locate(&p, 0)) == NULL)
 684                                 goto done;
 685                         err = -EPERM;
 686                         if (t == netdev_priv(ipip6_fb_tunnel_dev))
 687                                 goto done;
 688                         dev = t->dev;
 689                 }
 690                 err = unregister_netdevice(dev);
 691                 break;
 692
 693         default:
 694                 err = -EINVAL;
 695         }
 696
 697 done:
 698         return err;
 699 }
 700
 701 static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev)
 702 {
 703         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
 704 }
 705
 706 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
 707 {
 708         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
 709                 return -EINVAL;
 710         dev->mtu = new_mtu;
 711         return 0;
 712 }
 713
 714 static void ipip6_tunnel_setup(struct net_device *dev)
 715 {
 716         SET_MODULE_OWNER(dev);
 717         dev->uninit             = ipip6_tunnel_uninit;
 718         dev->destructor         = free_netdev;
 719         dev->hard_start_xmit    = ipip6_tunnel_xmit;
 720         dev->get_stats          = ipip6_tunnel_get_stats;
 721         dev->do_ioctl           = ipip6_tunnel_ioctl;
 722         dev->change_mtu         = ipip6_tunnel_change_mtu;
 723
 724         dev->type               = ARPHRD_SIT;
 725         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
 726         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
 727         dev->flags              = IFF_NOARP;
 728         dev->iflink             = 0;
 729         dev->addr_len           = 4;
 730 }
 731
 732 static int ipip6_tunnel_init(struct net_device *dev)
 733 {
 734         struct net_device *tdev = NULL;
 735         struct ip_tunnel *tunnel;
 736         struct iphdr *iph;
 737
 738         tunnel = netdev_priv(dev);
 739         iph = &tunnel->parms.iph;
 740
 741         tunnel->dev = dev;
 742         strcpy(tunnel->parms.name, dev->name);
 743
 744         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 745         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 746
 747         if (iph->daddr) {
 748                 struct flowi fl = { .nl_u = { .ip4_u =
 749                                               { .daddr = iph->daddr,
 750                                                 .saddr = iph->saddr,
 751                                                 .tos = RT_TOS(iph->tos) } },
 752                                     .oif = tunnel->parms.link,
 753                                     .proto = IPPROTO_IPV6 };
 754                 struct rtable *rt;
 755                 if (!ip_route_output_key(&rt, &fl)) {
 756                         tdev = rt->u.dst.dev;
 757                         ip_rt_put(rt);
 758                 }
 759                 dev->flags |= IFF_POINTOPOINT;
 760         }
 761
 762         if (!tdev && tunnel->parms.link)
 763                 tdev = __dev_get_by_index(tunnel->parms.link);
 764
 765         if (tdev) {
 766                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 767                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 768                 if (dev->mtu < IPV6_MIN_MTU)
 769                         dev->mtu = IPV6_MIN_MTU;
 770         }
 771         dev->iflink = tunnel->parms.link;
 772
 773         return 0;
 774 }
 775
 776 static int __init ipip6_fb_tunnel_init(struct net_device *dev)
 777 {
 778         struct ip_tunnel *tunnel = netdev_priv(dev);
 779         struct iphdr *iph = &tunnel->parms.iph;
 780
 781         tunnel->dev = dev;
 782         strcpy(tunnel->parms.name, dev->name);
 783
 784         iph->version            = 4;
 785         iph->protocol           = IPPROTO_IPV6;
 786         iph->ihl                = 5;
 787         iph->ttl                = 64;
 788
 789         dev_hold(dev);
 790         tunnels_wc[0]           = tunnel;
 791         return 0;
 792 }
 793
 794 static struct net_protocol sit_protocol = {
 795         .handler        =       ipip6_rcv,
 796         .err_handler    =       ipip6_err,
 797 };
 798
 799 static void __exit sit_destroy_tunnels(void)
 800 {
 801         int prio;
 802
 803         for (prio = 1; prio < 4; prio++) {
 804                 int h;
 805                 for (h = 0; h < HASH_SIZE; h++) {
 806                         struct ip_tunnel *t;
 807                         while ((t = tunnels[prio][h]) != NULL)
 808                                 unregister_netdevice(t->dev);
 809                 }
 810         }
 811 }
 812
 813 void __exit sit_cleanup(void)
 814 {
 815         inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
 816
 817         rtnl_lock();
 818         sit_destroy_tunnels();
 819         unregister_netdevice(ipip6_fb_tunnel_dev);
 820         rtnl_unlock();
 821 }
 822
 823 int __init sit_init(void)
 824 {
 825         int err;
 826
 827         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
 828
 829         if (inet_add_protocol(&sit_protocol, IPPROTO_IPV6) < 0) {
 830                 printk(KERN_INFO "sit init: Can't add protocol\n");
 831                 return -EAGAIN;
 832         }
 833
 834         ipip6_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
 835                                            ipip6_tunnel_setup);
 836         if (!ipip6_fb_tunnel_dev) {
 837                 err = -ENOMEM;
 838                 goto err1;
 839         }
 840
 841         ipip6_fb_tunnel_dev->init = ipip6_fb_tunnel_init;
 842
 843         if ((err =  register_netdev(ipip6_fb_tunnel_dev)))
 844                 goto err2;
 845
 846  out:
 847         return err;
 848  err2:
 849         free_netdev(ipip6_fb_tunnel_dev);
 850  err1:
 851         inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
 852         goto out;
 853 }