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  *      $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/config.h>
  22 #include <linux/module.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
  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
  55 /*
  56    This version of net/ipv6/sit.c is cloned of net/ipv4/ip_gre.c
  57
  58    For comments look at net/ipv4/ip_gre.c --ANK
  59  */
  60
  61 #define HASH_SIZE  16
  62 #define HASH(addr) ((addr^(addr>>4))&0xF)
  63
  64 static int ipip6_fb_tunnel_init(struct net_device *dev);
  65 static int ipip6_tunnel_init(struct net_device *dev);
  66 static void ipip6_tunnel_setup(struct net_device *dev);
  67
  68 static struct net_device *ipip6_fb_tunnel_dev;
  69
  70 static struct ip_tunnel *tunnels_r_l[HASH_SIZE];
  71 static struct ip_tunnel *tunnels_r[HASH_SIZE];
  72 static struct ip_tunnel *tunnels_l[HASH_SIZE];
  73 static struct ip_tunnel *tunnels_wc[1];
  74 static struct ip_tunnel **tunnels[4] = { tunnels_wc, tunnels_l, tunnels_r, tunnels_r_l };
  75
  76 static DEFINE_RWLOCK(ipip6_lock);
  77
  78 static struct ip_tunnel * ipip6_tunnel_lookup(u32 remote, u32 local)
  79 {
  80         unsigned h0 = HASH(remote);
  81         unsigned h1 = HASH(local);
  82         struct ip_tunnel *t;
  83
  84         for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
  85                 if (local == t->parms.iph.saddr &&
  86                     remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
  87                         return t;
  88         }
  89         for (t = tunnels_r[h0]; t; t = t->next) {
  90                 if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
  91                         return t;
  92         }
  93         for (t = tunnels_l[h1]; t; t = t->next) {
  94                 if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
  95                         return t;
  96         }
  97         if ((t = tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP))
  98                 return t;
  99         return NULL;
 100 }
 101
 102 static struct ip_tunnel ** ipip6_bucket(struct ip_tunnel *t)
 103 {
 104         u32 remote = t->parms.iph.daddr;
 105         u32 local = t->parms.iph.saddr;
 106         unsigned h = 0;
 107         int prio = 0;
 108
 109         if (remote) {
 110                 prio |= 2;
 111                 h ^= HASH(remote);
 112         }
 113         if (local) {
 114                 prio |= 1;
 115                 h ^= HASH(local);
 116         }
 117         return &tunnels[prio][h];
 118 }
 119
 120 static void ipip6_tunnel_unlink(struct ip_tunnel *t)
 121 {
 122         struct ip_tunnel **tp;
 123
 124         for (tp = ipip6_bucket(t); *tp; tp = &(*tp)->next) {
 125                 if (t == *tp) {
 126                         write_lock_bh(&ipip6_lock);
 127                         *tp = t->next;
 128                         write_unlock_bh(&ipip6_lock);
 129                         break;
 130                 }
 131         }
 132 }
 133
 134 static void ipip6_tunnel_link(struct ip_tunnel *t)
 135 {
 136         struct ip_tunnel **tp = ipip6_bucket(t);
 137
 138         t->next = *tp;
 139         write_lock_bh(&ipip6_lock);
 140         *tp = t;
 141         write_unlock_bh(&ipip6_lock);
 142 }
 143
 144 static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create)
 145 {
 146         u32 remote = parms->iph.daddr;
 147         u32 local = parms->iph.saddr;
 148         struct ip_tunnel *t, **tp, *nt;
 149         struct net_device *dev;
 150         unsigned h = 0;
 151         int prio = 0;
 152         char name[IFNAMSIZ];
 153
 154         if (remote) {
 155                 prio |= 2;
 156                 h ^= HASH(remote);
 157         }
 158         if (local) {
 159                 prio |= 1;
 160                 h ^= HASH(local);
 161         }
 162         for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
 163                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
 164                         return t;
 165         }
 166         if (!create)
 167                 goto failed;
 168
 169         if (parms->name[0])
 170                 strlcpy(name, parms->name, IFNAMSIZ);
 171         else {
 172                 int i;
 173                 for (i=1; i<100; i++) {
 174                         sprintf(name, "sit%d", i);
 175                         if (__dev_get_by_name(name) == NULL)
 176                                 break;
 177                 }
 178                 if (i==100)
 179                         goto failed;
 180         }
 181
 182         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
 183         if (dev == NULL)
 184                 return NULL;
 185
 186         nt = dev->priv;
 187         dev->init = ipip6_tunnel_init;
 188         nt->parms = *parms;
 189
 190         if (register_netdevice(dev) < 0) {
 191                 free_netdev(dev);
 192                 goto failed;
 193         }
 194
 195         dev_hold(dev);
 196
 197         ipip6_tunnel_link(nt);
 198         /* Do not decrement MOD_USE_COUNT here. */
 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((struct ip_tunnel*)dev->priv);
 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 = (struct ip_tunnel*)rt6i->rt6i_dev->priv;
 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                 skb->protocol = htons(ETH_P_IPV6);
 385                 skb->pkt_type = PACKET_HOST;
 386                 tunnel->stat.rx_packets++;
 387                 tunnel->stat.rx_bytes += skb->len;
 388                 skb->dev = tunnel->dev;
 389                 dst_release(skb->dst);
 390                 skb->dst = NULL;
 391                 nf_reset(skb);
 392                 ipip6_ecn_decapsulate(iph, skb);
 393                 netif_rx(skb);
 394                 read_unlock(&ipip6_lock);
 395                 return 0;
 396         }
 397
 398         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
 399         kfree_skb(skb);
 400         read_unlock(&ipip6_lock);
 401 out:
 402         return 0;
 403 }
 404
 405 /* Returns the embedded IPv4 address if the IPv6 address
 406    comes from 6to4 (RFC 3056) addr space */
 407
 408 static inline u32 try_6to4(struct in6_addr *v6dst)
 409 {
 410         u32 dst = 0;
 411
 412         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 413                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 414                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 415         }
 416         return dst;
 417 }
 418
 419 /*
 420  *      This function assumes it is being called from dev_queue_xmit()
 421  *      and that skb is filled properly by that function.
 422  */
 423
 424 static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 425 {
 426         struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
 427         struct net_device_stats *stats = &tunnel->stat;
 428         struct iphdr  *tiph = &tunnel->parms.iph;
 429         struct ipv6hdr *iph6 = skb->nh.ipv6h;
 430         u8     tos = tunnel->parms.iph.tos;
 431         struct rtable *rt;                      /* Route to the other host */
 432         struct net_device *tdev;                        /* Device to other host */
 433         struct iphdr  *iph;                     /* Our new IP header */
 434         int    max_headroom;                    /* The extra header space needed */
 435         u32    dst = tiph->daddr;
 436         int    mtu;
 437         struct in6_addr *addr6;
 438         int addr_type;
 439
 440         if (tunnel->recursion++) {
 441                 tunnel->stat.collisions++;
 442                 goto tx_error;
 443         }
 444
 445         if (skb->protocol != htons(ETH_P_IPV6))
 446                 goto tx_error;
 447
 448         if (!dst)
 449                 dst = try_6to4(&iph6->daddr);
 450
 451         if (!dst) {
 452                 struct neighbour *neigh = NULL;
 453
 454                 if (skb->dst)
 455                         neigh = skb->dst->neighbour;
 456
 457                 if (neigh == NULL) {
 458                         if (net_ratelimit())
 459                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 460                         goto tx_error;
 461                 }
 462
 463                 addr6 = (struct in6_addr*)&neigh->primary_key;
 464                 addr_type = ipv6_addr_type(addr6);
 465
 466                 if (addr_type == IPV6_ADDR_ANY) {
 467                         addr6 = &skb->nh.ipv6h->daddr;
 468                         addr_type = ipv6_addr_type(addr6);
 469                 }
 470
 471                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 472                         goto tx_error_icmp;
 473
 474                 dst = addr6->s6_addr32[3];
 475         }
 476
 477         {
 478                 struct flowi fl = { .nl_u = { .ip4_u =
 479                                               { .daddr = dst,
 480                                                 .saddr = tiph->saddr,
 481                                                 .tos = RT_TOS(tos) } },
 482                                     .oif = tunnel->parms.link,
 483                                     .proto = IPPROTO_IPV6 };
 484                 if (ip_route_output_key(&rt, &fl)) {
 485                         tunnel->stat.tx_carrier_errors++;
 486                         goto tx_error_icmp;
 487                 }
 488         }
 489         if (rt->rt_type != RTN_UNICAST) {
 490                 ip_rt_put(rt);
 491                 tunnel->stat.tx_carrier_errors++;
 492                 goto tx_error_icmp;
 493         }
 494         tdev = rt->u.dst.dev;
 495
 496         if (tdev == dev) {
 497                 ip_rt_put(rt);
 498                 tunnel->stat.collisions++;
 499                 goto tx_error;
 500         }
 501
 502         if (tiph->frag_off)
 503                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 504         else
 505                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 506
 507         if (mtu < 68) {
 508                 tunnel->stat.collisions++;
 509                 ip_rt_put(rt);
 510                 goto tx_error;
 511         }
 512         if (mtu < IPV6_MIN_MTU)
 513                 mtu = IPV6_MIN_MTU;
 514         if (tunnel->parms.iph.daddr && skb->dst)
 515                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 516
 517         if (skb->len > mtu) {
 518                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 519                 ip_rt_put(rt);
 520                 goto tx_error;
 521         }
 522
 523         if (tunnel->err_count > 0) {
 524                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 525                         tunnel->err_count--;
 526                         dst_link_failure(skb);
 527                 } else
 528                         tunnel->err_count = 0;
 529         }
 530
 531         /*
 532          * Okay, now see if we can stuff it in the buffer as-is.
 533          */
 534         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 535
 536         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 537                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 538                 if (!new_skb) {
 539                         ip_rt_put(rt);
 540                         stats->tx_dropped++;
 541                         dev_kfree_skb(skb);
 542                         tunnel->recursion--;
 543                         return 0;
 544                 }
 545                 if (skb->sk)
 546                         skb_set_owner_w(new_skb, skb->sk);
 547                 dev_kfree_skb(skb);
 548                 skb = new_skb;
 549                 iph6 = skb->nh.ipv6h;
 550         }
 551
 552         skb->h.raw = skb->nh.raw;
 553         skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
 554         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 555         dst_release(skb->dst);
 556         skb->dst = &rt->u.dst;
 557
 558         /*
 559          *      Push down and install the IPIP header.
 560          */
 561
 562         iph                     =       skb->nh.iph;
 563         iph->version            =       4;
 564         iph->ihl                =       sizeof(struct iphdr)>>2;
 565         if (mtu > IPV6_MIN_MTU)
 566                 iph->frag_off   =       htons(IP_DF);
 567         else
 568                 iph->frag_off   =       0;
 569
 570         iph->protocol           =       IPPROTO_IPV6;
 571         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 572         iph->daddr              =       rt->rt_dst;
 573         iph->saddr              =       rt->rt_src;
 574
 575         if ((iph->ttl = tiph->ttl) == 0)
 576                 iph->ttl        =       iph6->hop_limit;
 577
 578         nf_reset(skb);
 579
 580         IPTUNNEL_XMIT();
 581         tunnel->recursion--;
 582         return 0;
 583
 584 tx_error_icmp:
 585         dst_link_failure(skb);
 586 tx_error:
 587         stats->tx_errors++;
 588         dev_kfree_skb(skb);
 589         tunnel->recursion--;
 590         return 0;
 591 }
 592
 593 static int
 594 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 595 {
 596         int err = 0;
 597         struct ip_tunnel_parm p;
 598         struct ip_tunnel *t;
 599
 600         switch (cmd) {
 601         case SIOCGETTUNNEL:
 602                 t = NULL;
 603                 if (dev == ipip6_fb_tunnel_dev) {
 604                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 605                                 err = -EFAULT;
 606                                 break;
 607                         }
 608                         t = ipip6_tunnel_locate(&p, 0);
 609                 }
 610                 if (t == NULL)
 611                         t = (struct ip_tunnel*)dev->priv;
 612                 memcpy(&p, &t->parms, sizeof(p));
 613                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 614                         err = -EFAULT;
 615                 break;
 616
 617         case SIOCADDTUNNEL:
 618         case SIOCCHGTUNNEL:
 619                 err = -EPERM;
 620                 if (!capable(CAP_NET_ADMIN))
 621                         goto done;
 622
 623                 err = -EFAULT;
 624                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 625                         goto done;
 626
 627                 err = -EINVAL;
 628                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 629                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 630                         goto done;
 631                 if (p.iph.ttl)
 632                         p.iph.frag_off |= htons(IP_DF);
 633
 634                 t = ipip6_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 635
 636                 if (dev != ipip6_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 637                         if (t != NULL) {
 638                                 if (t->dev != dev) {
 639                                         err = -EEXIST;
 640                                         break;
 641                                 }
 642                         } else {
 643                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 644                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 645                                         err = -EINVAL;
 646                                         break;
 647                                 }
 648                                 t = (struct ip_tunnel*)dev->priv;
 649                                 ipip6_tunnel_unlink(t);
 650                                 t->parms.iph.saddr = p.iph.saddr;
 651                                 t->parms.iph.daddr = p.iph.daddr;
 652                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 653                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 654                                 ipip6_tunnel_link(t);
 655                                 netdev_state_change(dev);
 656                         }
 657                 }
 658
 659                 if (t) {
 660                         err = 0;
 661                         if (cmd == SIOCCHGTUNNEL) {
 662                                 t->parms.iph.ttl = p.iph.ttl;
 663                                 t->parms.iph.tos = p.iph.tos;
 664                         }
 665                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 666                                 err = -EFAULT;
 667                 } else
 668                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 669                 break;
 670
 671         case SIOCDELTUNNEL:
 672                 err = -EPERM;
 673                 if (!capable(CAP_NET_ADMIN))
 674                         goto done;
 675
 676                 if (dev == ipip6_fb_tunnel_dev) {
 677                         err = -EFAULT;
 678                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 679                                 goto done;
 680                         err = -ENOENT;
 681                         if ((t = ipip6_tunnel_locate(&p, 0)) == NULL)
 682                                 goto done;
 683                         err = -EPERM;
 684                         if (t == ipip6_fb_tunnel_dev->priv)
 685                                 goto done;
 686                         dev = t->dev;
 687                 }
 688                 err = unregister_netdevice(dev);
 689                 break;
 690
 691         default:
 692                 err = -EINVAL;
 693         }
 694
 695 done:
 696         return err;
 697 }
 698
 699 static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev)
 700 {
 701         return &(((struct ip_tunnel*)dev->priv)->stat);
 702 }
 703
 704 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
 705 {
 706         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
 707                 return -EINVAL;
 708         dev->mtu = new_mtu;
 709         return 0;
 710 }
 711
 712 static void ipip6_tunnel_setup(struct net_device *dev)
 713 {
 714         SET_MODULE_OWNER(dev);
 715         dev->uninit             = ipip6_tunnel_uninit;
 716         dev->destructor         = free_netdev;
 717         dev->hard_start_xmit    = ipip6_tunnel_xmit;
 718         dev->get_stats          = ipip6_tunnel_get_stats;
 719         dev->do_ioctl           = ipip6_tunnel_ioctl;
 720         dev->change_mtu         = ipip6_tunnel_change_mtu;
 721
 722         dev->type               = ARPHRD_SIT;
 723         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
 724         dev->mtu                = 1500 - sizeof(struct iphdr);
 725         dev->flags              = IFF_NOARP;
 726         dev->iflink             = 0;
 727         dev->addr_len           = 4;
 728 }
 729
 730 static int ipip6_tunnel_init(struct net_device *dev)
 731 {
 732         struct net_device *tdev = NULL;
 733         struct ip_tunnel *tunnel;
 734         struct iphdr *iph;
 735
 736         tunnel = (struct ip_tunnel*)dev->priv;
 737         iph = &tunnel->parms.iph;
 738
 739         tunnel->dev = dev;
 740         strcpy(tunnel->parms.name, dev->name);
 741
 742         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 743         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 744
 745         if (iph->daddr) {
 746                 struct flowi fl = { .nl_u = { .ip4_u =
 747                                               { .daddr = iph->daddr,
 748                                                 .saddr = iph->saddr,
 749                                                 .tos = RT_TOS(iph->tos) } },
 750                                     .oif = tunnel->parms.link,
 751                                     .proto = IPPROTO_IPV6 };
 752                 struct rtable *rt;
 753                 if (!ip_route_output_key(&rt, &fl)) {
 754                         tdev = rt->u.dst.dev;
 755                         ip_rt_put(rt);
 756                 }
 757                 dev->flags |= IFF_POINTOPOINT;
 758         }
 759
 760         if (!tdev && tunnel->parms.link)
 761                 tdev = __dev_get_by_index(tunnel->parms.link);
 762
 763         if (tdev) {
 764                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 765                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 766                 if (dev->mtu < IPV6_MIN_MTU)
 767                         dev->mtu = IPV6_MIN_MTU;
 768         }
 769         dev->iflink = tunnel->parms.link;
 770
 771         return 0;
 772 }
 773
 774 int __init ipip6_fb_tunnel_init(struct net_device *dev)
 775 {
 776         struct ip_tunnel *tunnel = dev->priv;
 777         struct iphdr *iph = &tunnel->parms.iph;
 778
 779         tunnel->dev = dev;
 780         strcpy(tunnel->parms.name, dev->name);
 781
 782         iph->version            = 4;
 783         iph->protocol           = IPPROTO_IPV6;
 784         iph->ihl                = 5;
 785         iph->ttl                = 64;
 786
 787         dev_hold(dev);
 788         tunnels_wc[0]           = tunnel;
 789         return 0;
 790 }
 791
 792 static struct net_protocol sit_protocol = {
 793         .handler        =       ipip6_rcv,
 794         .err_handler    =       ipip6_err,
 795 };
 796
 797 void __exit sit_cleanup(void)
 798 {
 799         inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
 800         unregister_netdev(ipip6_fb_tunnel_dev);
 801 }
 802
 803 int __init sit_init(void)
 804 {
 805         int err;
 806
 807         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
 808
 809         if (inet_add_protocol(&sit_protocol, IPPROTO_IPV6) < 0) {
 810                 printk(KERN_INFO "sit init: Can't add protocol\n");
 811                 return -EAGAIN;
 812         }
 813
 814         ipip6_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
 815                                            ipip6_tunnel_setup);
 816         if (!ipip6_fb_tunnel_dev) {
 817                 err = -ENOMEM;
 818                 goto err1;
 819         }
 820
 821         ipip6_fb_tunnel_dev->init = ipip6_fb_tunnel_init;
 822
 823         if ((err =  register_netdev(ipip6_fb_tunnel_dev)))
 824                 goto err2;
 825
 826  out:
 827         return err;
 828  err2:
 829         free_netdev(ipip6_fb_tunnel_dev);
 830  err1:
 831         inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
 832         goto out;
 833 }