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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  * Fred L. Templin <fltemplin@acm.org>:         isatap support
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/capability.h>
  24 #include <linux/errno.h>
  25 #include <linux/types.h>
  26 #include <linux/socket.h>
  27 #include <linux/sockios.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) (((__force u32)addr^((__force u32)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(__be32 remote, __be32 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_parm *parms)
 104 {
 105         __be32 remote = parms->iph.daddr;
 106         __be32 local = 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 inline struct ip_tunnel **ipip6_bucket(struct ip_tunnel *t)
 122 {
 123         return __ipip6_bucket(&t->parms);
 124 }
 125
 126 static void ipip6_tunnel_unlink(struct ip_tunnel *t)
 127 {
 128         struct ip_tunnel **tp;
 129
 130         for (tp = ipip6_bucket(t); *tp; tp = &(*tp)->next) {
 131                 if (t == *tp) {
 132                         write_lock_bh(&ipip6_lock);
 133                         *tp = t->next;
 134                         write_unlock_bh(&ipip6_lock);
 135                         break;
 136                 }
 137         }
 138 }
 139
 140 static void ipip6_tunnel_link(struct ip_tunnel *t)
 141 {
 142         struct ip_tunnel **tp = ipip6_bucket(t);
 143
 144         t->next = *tp;
 145         write_lock_bh(&ipip6_lock);
 146         *tp = t;
 147         write_unlock_bh(&ipip6_lock);
 148 }
 149
 150 static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create)
 151 {
 152         __be32 remote = parms->iph.daddr;
 153         __be32 local = parms->iph.saddr;
 154         struct ip_tunnel *t, **tp, *nt;
 155         struct net_device *dev;
 156         char name[IFNAMSIZ];
 157
 158         for (tp = __ipip6_bucket(parms); (t = *tp) != NULL; tp = &t->next) {
 159                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
 160                         return t;
 161         }
 162         if (!create)
 163                 goto failed;
 164
 165         if (parms->name[0])
 166                 strlcpy(name, parms->name, IFNAMSIZ);
 167         else
 168                 sprintf(name, "sit%%d");
 169
 170         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
 171         if (dev == NULL)
 172                 return NULL;
 173
 174         if (strchr(name, '%')) {
 175                 if (dev_alloc_name(dev, name) < 0)
 176                         goto failed_free;
 177         }
 178
 179         nt = netdev_priv(dev);
 180         dev->init = ipip6_tunnel_init;
 181         nt->parms = *parms;
 182
 183         if (parms->i_flags & SIT_ISATAP)
 184                 dev->priv_flags |= IFF_ISATAP;
 185
 186         if (register_netdevice(dev) < 0)
 187                 goto failed_free;
 188
 189         dev_hold(dev);
 190
 191         ipip6_tunnel_link(nt);
 192         return nt;
 193
 194 failed_free:
 195         free_netdev(dev);
 196 failed:
 197         return NULL;
 198 }
 199
 200 static void ipip6_tunnel_uninit(struct net_device *dev)
 201 {
 202         if (dev == ipip6_fb_tunnel_dev) {
 203                 write_lock_bh(&ipip6_lock);
 204                 tunnels_wc[0] = NULL;
 205                 write_unlock_bh(&ipip6_lock);
 206                 dev_put(dev);
 207         } else {
 208                 ipip6_tunnel_unlink(netdev_priv(dev));
 209                 dev_put(dev);
 210         }
 211 }
 212
 213
 214 static int ipip6_err(struct sk_buff *skb, u32 info)
 215 {
 216 #ifndef I_WISH_WORLD_WERE_PERFECT
 217
 218 /* It is not :-( All the routers (except for Linux) return only
 219    8 bytes of packet payload. It means, that precise relaying of
 220    ICMP in the real Internet is absolutely infeasible.
 221  */
 222         struct iphdr *iph = (struct iphdr*)skb->data;
 223         const int type = icmp_hdr(skb)->type;
 224         const int code = icmp_hdr(skb)->code;
 225         struct ip_tunnel *t;
 226         int err;
 227
 228         switch (type) {
 229         default:
 230         case ICMP_PARAMETERPROB:
 231                 return 0;
 232
 233         case ICMP_DEST_UNREACH:
 234                 switch (code) {
 235                 case ICMP_SR_FAILED:
 236                 case ICMP_PORT_UNREACH:
 237                         /* Impossible event. */
 238                         return 0;
 239                 case ICMP_FRAG_NEEDED:
 240                         /* Soft state for pmtu is maintained by IP core. */
 241                         return 0;
 242                 default:
 243                         /* All others are translated to HOST_UNREACH.
 244                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 245                            I believe they are just ether pollution. --ANK
 246                          */
 247                         break;
 248                 }
 249                 break;
 250         case ICMP_TIME_EXCEEDED:
 251                 if (code != ICMP_EXC_TTL)
 252                         return 0;
 253                 break;
 254         }
 255
 256         err = -ENOENT;
 257
 258         read_lock(&ipip6_lock);
 259         t = ipip6_tunnel_lookup(iph->daddr, iph->saddr);
 260         if (t == NULL || t->parms.iph.daddr == 0)
 261                 goto out;
 262
 263         err = 0;
 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 err;
 275 #else
 276         struct iphdr *iph = (struct iphdr*)dp;
 277         int hlen = iph->ihl<<2;
 278         struct ipv6hdr *iph6;
 279         const int type = icmp_hdr(skb)->type;
 280         const int code = icmp_hdr(skb)->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 (icmp_hdr(skb)->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 = icmp_hdr(skb)->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 0;
 336         dst_release(skb2->dst);
 337         skb2->dst = NULL;
 338         skb_pull(skb2, skb->data - (u8*)iph6);
 339         skb_reset_network_header(skb2);
 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 0;
 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(ipv6_hdr(skb));
 366 }
 367
 368 /* ISATAP (RFC4214) - check source address */
 369 static int
 370 isatap_srcok(struct sk_buff *skb, struct iphdr *iph, struct net_device *dev)
 371 {
 372         struct neighbour *neigh;
 373         struct dst_entry *dst;
 374         struct rt6_info *rt;
 375         struct flowi fl;
 376         struct in6_addr *addr6;
 377         struct in6_addr rtr;
 378         struct ipv6hdr *iph6;
 379         int ok = 0;
 380
 381         /* from onlink default router */
 382         ipv6_addr_set(&rtr,  htonl(0xFE800000), 0, 0, 0);
 383         ipv6_isatap_eui64(rtr.s6_addr + 8, iph->saddr);
 384         if ((rt = rt6_get_dflt_router(&rtr, dev))) {
 385                 dst_release(&rt->u.dst);
 386                 return 1;
 387         }
 388
 389         iph6 = ipv6_hdr(skb);
 390         memset(&fl, 0, sizeof(fl));
 391         fl.proto = iph6->nexthdr;
 392         ipv6_addr_copy(&fl.fl6_dst, &iph6->saddr);
 393         fl.oif = dev->ifindex;
 394         security_skb_classify_flow(skb, &fl);
 395
 396         dst = ip6_route_output(NULL, &fl);
 397         if (!dst->error && (dst->dev == dev) && (neigh = dst->neighbour)) {
 398
 399                 addr6 = (struct in6_addr*)&neigh->primary_key;
 400
 401                 /* from correct previous hop */
 402                 if (ipv6_addr_is_isatap(addr6) &&
 403                     (addr6->s6_addr32[3] == iph->saddr))
 404                         ok = 1;
 405         }
 406         dst_release(dst);
 407         return ok;
 408 }
 409
 410 static int ipip6_rcv(struct sk_buff *skb)
 411 {
 412         struct iphdr *iph;
 413         struct ip_tunnel *tunnel;
 414
 415         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 416                 goto out;
 417
 418         iph = ip_hdr(skb);
 419
 420         read_lock(&ipip6_lock);
 421         if ((tunnel = ipip6_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
 422                 secpath_reset(skb);
 423                 skb->mac_header = skb->network_header;
 424                 skb_reset_network_header(skb);
 425                 IPCB(skb)->flags = 0;
 426                 skb->protocol = htons(ETH_P_IPV6);
 427                 skb->pkt_type = PACKET_HOST;
 428
 429                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
 430                     !isatap_srcok(skb, iph, tunnel->dev)) {
 431                         tunnel->stat.rx_errors++;
 432                         read_unlock(&ipip6_lock);
 433                         kfree_skb(skb);
 434                         return 0;
 435                 }
 436                 tunnel->stat.rx_packets++;
 437                 tunnel->stat.rx_bytes += skb->len;
 438                 skb->dev = tunnel->dev;
 439                 dst_release(skb->dst);
 440                 skb->dst = NULL;
 441                 nf_reset(skb);
 442                 ipip6_ecn_decapsulate(iph, skb);
 443                 netif_rx(skb);
 444                 read_unlock(&ipip6_lock);
 445                 return 0;
 446         }
 447
 448         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 449         kfree_skb(skb);
 450         read_unlock(&ipip6_lock);
 451 out:
 452         return 0;
 453 }
 454
 455 /* Returns the embedded IPv4 address if the IPv6 address
 456    comes from 6to4 (RFC 3056) addr space */
 457
 458 static inline __be32 try_6to4(struct in6_addr *v6dst)
 459 {
 460         __be32 dst = 0;
 461
 462         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 463                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 464                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 465         }
 466         return dst;
 467 }
 468
 469 /*
 470  *      This function assumes it is being called from dev_queue_xmit()
 471  *      and that skb is filled properly by that function.
 472  */
 473
 474 static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 475 {
 476         struct ip_tunnel *tunnel = netdev_priv(dev);
 477         struct net_device_stats *stats = &tunnel->stat;
 478         struct iphdr  *tiph = &tunnel->parms.iph;
 479         struct ipv6hdr *iph6 = ipv6_hdr(skb);
 480         u8     tos = tunnel->parms.iph.tos;
 481         struct rtable *rt;                      /* Route to the other host */
 482         struct net_device *tdev;                        /* Device to other host */
 483         struct iphdr  *iph;                     /* Our new IP header */
 484         unsigned int max_headroom;              /* The extra header space needed */
 485         __be32 dst = tiph->daddr;
 486         int    mtu;
 487         struct in6_addr *addr6;
 488         int addr_type;
 489
 490         if (tunnel->recursion++) {
 491                 tunnel->stat.collisions++;
 492                 goto tx_error;
 493         }
 494
 495         if (skb->protocol != htons(ETH_P_IPV6))
 496                 goto tx_error;
 497
 498         /* ISATAP (RFC4214) - must come before 6to4 */
 499         if (dev->priv_flags & IFF_ISATAP) {
 500                 struct neighbour *neigh = NULL;
 501
 502                 if (skb->dst)
 503                         neigh = skb->dst->neighbour;
 504
 505                 if (neigh == NULL) {
 506                         if (net_ratelimit())
 507                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 508                         goto tx_error;
 509                 }
 510
 511                 addr6 = (struct in6_addr*)&neigh->primary_key;
 512                 addr_type = ipv6_addr_type(addr6);
 513
 514                 if ((addr_type & IPV6_ADDR_UNICAST) &&
 515                      ipv6_addr_is_isatap(addr6))
 516                         dst = addr6->s6_addr32[3];
 517                 else
 518                         goto tx_error;
 519         }
 520
 521         if (!dst)
 522                 dst = try_6to4(&iph6->daddr);
 523
 524         if (!dst) {
 525                 struct neighbour *neigh = NULL;
 526
 527                 if (skb->dst)
 528                         neigh = skb->dst->neighbour;
 529
 530                 if (neigh == NULL) {
 531                         if (net_ratelimit())
 532                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 533                         goto tx_error;
 534                 }
 535
 536                 addr6 = (struct in6_addr*)&neigh->primary_key;
 537                 addr_type = ipv6_addr_type(addr6);
 538
 539                 if (addr_type == IPV6_ADDR_ANY) {
 540                         addr6 = &ipv6_hdr(skb)->daddr;
 541                         addr_type = ipv6_addr_type(addr6);
 542                 }
 543
 544                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 545                         goto tx_error_icmp;
 546
 547                 dst = addr6->s6_addr32[3];
 548         }
 549
 550         {
 551                 struct flowi fl = { .nl_u = { .ip4_u =
 552                                               { .daddr = dst,
 553                                                 .saddr = tiph->saddr,
 554                                                 .tos = RT_TOS(tos) } },
 555                                     .oif = tunnel->parms.link,
 556                                     .proto = IPPROTO_IPV6 };
 557                 if (ip_route_output_key(&init_net, &rt, &fl)) {
 558                         tunnel->stat.tx_carrier_errors++;
 559                         goto tx_error_icmp;
 560                 }
 561         }
 562         if (rt->rt_type != RTN_UNICAST) {
 563                 ip_rt_put(rt);
 564                 tunnel->stat.tx_carrier_errors++;
 565                 goto tx_error_icmp;
 566         }
 567         tdev = rt->u.dst.dev;
 568
 569         if (tdev == dev) {
 570                 ip_rt_put(rt);
 571                 tunnel->stat.collisions++;
 572                 goto tx_error;
 573         }
 574
 575         if (tiph->frag_off)
 576                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 577         else
 578                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 579
 580         if (mtu < 68) {
 581                 tunnel->stat.collisions++;
 582                 ip_rt_put(rt);
 583                 goto tx_error;
 584         }
 585         if (mtu < IPV6_MIN_MTU)
 586                 mtu = IPV6_MIN_MTU;
 587         if (tunnel->parms.iph.daddr && skb->dst)
 588                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 589
 590         if (skb->len > mtu) {
 591                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 592                 ip_rt_put(rt);
 593                 goto tx_error;
 594         }
 595
 596         if (tunnel->err_count > 0) {
 597                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 598                         tunnel->err_count--;
 599                         dst_link_failure(skb);
 600                 } else
 601                         tunnel->err_count = 0;
 602         }
 603
 604         /*
 605          * Okay, now see if we can stuff it in the buffer as-is.
 606          */
 607         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 608
 609         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 610             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 611                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 612                 if (!new_skb) {
 613                         ip_rt_put(rt);
 614                         stats->tx_dropped++;
 615                         dev_kfree_skb(skb);
 616                         tunnel->recursion--;
 617                         return 0;
 618                 }
 619                 if (skb->sk)
 620                         skb_set_owner_w(new_skb, skb->sk);
 621                 dev_kfree_skb(skb);
 622                 skb = new_skb;
 623                 iph6 = ipv6_hdr(skb);
 624         }
 625
 626         skb->transport_header = skb->network_header;
 627         skb_push(skb, sizeof(struct iphdr));
 628         skb_reset_network_header(skb);
 629         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 630         IPCB(skb)->flags = 0;
 631         dst_release(skb->dst);
 632         skb->dst = &rt->u.dst;
 633
 634         /*
 635          *      Push down and install the IPIP header.
 636          */
 637
 638         iph                     =       ip_hdr(skb);
 639         iph->version            =       4;
 640         iph->ihl                =       sizeof(struct iphdr)>>2;
 641         if (mtu > IPV6_MIN_MTU)
 642                 iph->frag_off   =       htons(IP_DF);
 643         else
 644                 iph->frag_off   =       0;
 645
 646         iph->protocol           =       IPPROTO_IPV6;
 647         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 648         iph->daddr              =       rt->rt_dst;
 649         iph->saddr              =       rt->rt_src;
 650
 651         if ((iph->ttl = tiph->ttl) == 0)
 652                 iph->ttl        =       iph6->hop_limit;
 653
 654         nf_reset(skb);
 655
 656         IPTUNNEL_XMIT();
 657         tunnel->recursion--;
 658         return 0;
 659
 660 tx_error_icmp:
 661         dst_link_failure(skb);
 662 tx_error:
 663         stats->tx_errors++;
 664         dev_kfree_skb(skb);
 665         tunnel->recursion--;
 666         return 0;
 667 }
 668
 669 static void ipip6_tunnel_bind_dev(struct net_device *dev)
 670 {
 671         struct net_device *tdev = NULL;
 672         struct ip_tunnel *tunnel;
 673         struct iphdr *iph;
 674
 675         tunnel = netdev_priv(dev);
 676         iph = &tunnel->parms.iph;
 677
 678         if (iph->daddr) {
 679                 struct flowi fl = { .nl_u = { .ip4_u =
 680                                               { .daddr = iph->daddr,
 681                                                 .saddr = iph->saddr,
 682                                                 .tos = RT_TOS(iph->tos) } },
 683                                     .oif = tunnel->parms.link,
 684                                     .proto = IPPROTO_IPV6 };
 685                 struct rtable *rt;
 686                 if (!ip_route_output_key(&init_net, &rt, &fl)) {
 687                         tdev = rt->u.dst.dev;
 688                         ip_rt_put(rt);
 689                 }
 690                 dev->flags |= IFF_POINTOPOINT;
 691         }
 692
 693         if (!tdev && tunnel->parms.link)
 694                 tdev = __dev_get_by_index(&init_net, tunnel->parms.link);
 695
 696         if (tdev) {
 697                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 698                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 699                 if (dev->mtu < IPV6_MIN_MTU)
 700                         dev->mtu = IPV6_MIN_MTU;
 701         }
 702         dev->iflink = tunnel->parms.link;
 703 }
 704
 705 static int
 706 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 707 {
 708         int err = 0;
 709         struct ip_tunnel_parm p;
 710         struct ip_tunnel *t;
 711
 712         switch (cmd) {
 713         case SIOCGETTUNNEL:
 714                 t = NULL;
 715                 if (dev == ipip6_fb_tunnel_dev) {
 716                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 717                                 err = -EFAULT;
 718                                 break;
 719                         }
 720                         t = ipip6_tunnel_locate(&p, 0);
 721                 }
 722                 if (t == NULL)
 723                         t = netdev_priv(dev);
 724                 memcpy(&p, &t->parms, sizeof(p));
 725                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 726                         err = -EFAULT;
 727                 break;
 728
 729         case SIOCADDTUNNEL:
 730         case SIOCCHGTUNNEL:
 731                 err = -EPERM;
 732                 if (!capable(CAP_NET_ADMIN))
 733                         goto done;
 734
 735                 err = -EFAULT;
 736                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 737                         goto done;
 738
 739                 err = -EINVAL;
 740                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 741                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 742                         goto done;
 743                 if (p.iph.ttl)
 744                         p.iph.frag_off |= htons(IP_DF);
 745
 746                 t = ipip6_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 747
 748                 if (dev != ipip6_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 749                         if (t != NULL) {
 750                                 if (t->dev != dev) {
 751                                         err = -EEXIST;
 752                                         break;
 753                                 }
 754                         } else {
 755                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 756                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 757                                         err = -EINVAL;
 758                                         break;
 759                                 }
 760                                 t = netdev_priv(dev);
 761                                 ipip6_tunnel_unlink(t);
 762                                 t->parms.iph.saddr = p.iph.saddr;
 763                                 t->parms.iph.daddr = p.iph.daddr;
 764                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 765                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 766                                 ipip6_tunnel_link(t);
 767                                 netdev_state_change(dev);
 768                         }
 769                 }
 770
 771                 if (t) {
 772                         err = 0;
 773                         if (cmd == SIOCCHGTUNNEL) {
 774                                 t->parms.iph.ttl = p.iph.ttl;
 775                                 t->parms.iph.tos = p.iph.tos;
 776                                 if (t->parms.link != p.link) {
 777                                         t->parms.link = p.link;
 778                                         ipip6_tunnel_bind_dev(dev);
 779                                         netdev_state_change(dev);
 780                                 }
 781                         }
 782                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 783                                 err = -EFAULT;
 784                 } else
 785                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 786                 break;
 787
 788         case SIOCDELTUNNEL:
 789                 err = -EPERM;
 790                 if (!capable(CAP_NET_ADMIN))
 791                         goto done;
 792
 793                 if (dev == ipip6_fb_tunnel_dev) {
 794                         err = -EFAULT;
 795                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 796                                 goto done;
 797                         err = -ENOENT;
 798                         if ((t = ipip6_tunnel_locate(&p, 0)) == NULL)
 799                                 goto done;
 800                         err = -EPERM;
 801                         if (t == netdev_priv(ipip6_fb_tunnel_dev))
 802                                 goto done;
 803                         dev = t->dev;
 804                 }
 805                 unregister_netdevice(dev);
 806                 err = 0;
 807                 break;
 808
 809         default:
 810                 err = -EINVAL;
 811         }
 812
 813 done:
 814         return err;
 815 }
 816
 817 static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev)
 818 {
 819         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
 820 }
 821
 822 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
 823 {
 824         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
 825                 return -EINVAL;
 826         dev->mtu = new_mtu;
 827         return 0;
 828 }
 829
 830 static void ipip6_tunnel_setup(struct net_device *dev)
 831 {
 832         dev->uninit             = ipip6_tunnel_uninit;
 833         dev->destructor         = free_netdev;
 834         dev->hard_start_xmit    = ipip6_tunnel_xmit;
 835         dev->get_stats          = ipip6_tunnel_get_stats;
 836         dev->do_ioctl           = ipip6_tunnel_ioctl;
 837         dev->change_mtu         = ipip6_tunnel_change_mtu;
 838
 839         dev->type               = ARPHRD_SIT;
 840         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
 841         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
 842         dev->flags              = IFF_NOARP;
 843         dev->iflink             = 0;
 844         dev->addr_len           = 4;
 845 }
 846
 847 static int ipip6_tunnel_init(struct net_device *dev)
 848 {
 849         struct ip_tunnel *tunnel;
 850
 851         tunnel = netdev_priv(dev);
 852
 853         tunnel->dev = dev;
 854         strcpy(tunnel->parms.name, dev->name);
 855
 856         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 857         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 858
 859         ipip6_tunnel_bind_dev(dev);
 860
 861         return 0;
 862 }
 863
 864 static int __init ipip6_fb_tunnel_init(struct net_device *dev)
 865 {
 866         struct ip_tunnel *tunnel = netdev_priv(dev);
 867         struct iphdr *iph = &tunnel->parms.iph;
 868
 869         tunnel->dev = dev;
 870         strcpy(tunnel->parms.name, dev->name);
 871
 872         iph->version            = 4;
 873         iph->protocol           = IPPROTO_IPV6;
 874         iph->ihl                = 5;
 875         iph->ttl                = 64;
 876
 877         dev_hold(dev);
 878         tunnels_wc[0]           = tunnel;
 879         return 0;
 880 }
 881
 882 static struct xfrm_tunnel sit_handler = {
 883         .handler        =       ipip6_rcv,
 884         .err_handler    =       ipip6_err,
 885         .priority       =       1,
 886 };
 887
 888 static void __exit sit_destroy_tunnels(void)
 889 {
 890         int prio;
 891
 892         for (prio = 1; prio < 4; prio++) {
 893                 int h;
 894                 for (h = 0; h < HASH_SIZE; h++) {
 895                         struct ip_tunnel *t;
 896                         while ((t = tunnels[prio][h]) != NULL)
 897                                 unregister_netdevice(t->dev);
 898                 }
 899         }
 900 }
 901
 902 static void __exit sit_cleanup(void)
 903 {
 904         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
 905
 906         rtnl_lock();
 907         sit_destroy_tunnels();
 908         unregister_netdevice(ipip6_fb_tunnel_dev);
 909         rtnl_unlock();
 910 }
 911
 912 static int __init sit_init(void)
 913 {
 914         int err;
 915
 916         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
 917
 918         if (xfrm4_tunnel_register(&sit_handler, AF_INET6) < 0) {
 919                 printk(KERN_INFO "sit init: Can't add protocol\n");
 920                 return -EAGAIN;
 921         }
 922
 923         ipip6_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
 924                                            ipip6_tunnel_setup);
 925         if (!ipip6_fb_tunnel_dev) {
 926                 err = -ENOMEM;
 927                 goto err1;
 928         }
 929
 930         ipip6_fb_tunnel_dev->init = ipip6_fb_tunnel_init;
 931
 932         if ((err =  register_netdev(ipip6_fb_tunnel_dev)))
 933                 goto err2;
 934
 935  out:
 936         return err;
 937  err2:
 938         free_netdev(ipip6_fb_tunnel_dev);
 939  err1:
 940         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
 941         goto out;
 942 }
 943
 944 module_init(sit_init);
 945 module_exit(sit_cleanup);
 946 MODULE_LICENSE("GPL");
 947 MODULE_ALIAS("sit0");