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  * 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                 int i;
 169                 for (i=1; i<100; i++) {
 170                         sprintf(name, "sit%d", i);
 171                         if (__dev_get_by_name(&init_net, name) == NULL)
 172                                 break;
 173                 }
 174                 if (i==100)
 175                         goto failed;
 176         }
 177
 178         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
 179         if (dev == NULL)
 180                 return NULL;
 181
 182         nt = netdev_priv(dev);
 183         dev->init = ipip6_tunnel_init;
 184         nt->parms = *parms;
 185
 186         if (parms->i_flags & SIT_ISATAP)
 187                 dev->priv_flags |= IFF_ISATAP;
 188
 189         if (register_netdevice(dev) < 0) {
 190                 free_netdev(dev);
 191                 goto failed;
 192         }
 193
 194         dev_hold(dev);
 195
 196         ipip6_tunnel_link(nt);
 197         return nt;
 198
 199 failed:
 200         return NULL;
 201 }
 202
 203 static void ipip6_tunnel_uninit(struct net_device *dev)
 204 {
 205         if (dev == ipip6_fb_tunnel_dev) {
 206                 write_lock_bh(&ipip6_lock);
 207                 tunnels_wc[0] = NULL;
 208                 write_unlock_bh(&ipip6_lock);
 209                 dev_put(dev);
 210         } else {
 211                 ipip6_tunnel_unlink(netdev_priv(dev));
 212                 dev_put(dev);
 213         }
 214 }
 215
 216
 217 static int ipip6_err(struct sk_buff *skb, u32 info)
 218 {
 219 #ifndef I_WISH_WORLD_WERE_PERFECT
 220
 221 /* It is not :-( All the routers (except for Linux) return only
 222    8 bytes of packet payload. It means, that precise relaying of
 223    ICMP in the real Internet is absolutely infeasible.
 224  */
 225         struct iphdr *iph = (struct iphdr*)skb->data;
 226         const int type = icmp_hdr(skb)->type;
 227         const int code = icmp_hdr(skb)->code;
 228         struct ip_tunnel *t;
 229         int err;
 230
 231         switch (type) {
 232         default:
 233         case ICMP_PARAMETERPROB:
 234                 return 0;
 235
 236         case ICMP_DEST_UNREACH:
 237                 switch (code) {
 238                 case ICMP_SR_FAILED:
 239                 case ICMP_PORT_UNREACH:
 240                         /* Impossible event. */
 241                         return 0;
 242                 case ICMP_FRAG_NEEDED:
 243                         /* Soft state for pmtu is maintained by IP core. */
 244                         return 0;
 245                 default:
 246                         /* All others are translated to HOST_UNREACH.
 247                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 248                            I believe they are just ether pollution. --ANK
 249                          */
 250                         break;
 251                 }
 252                 break;
 253         case ICMP_TIME_EXCEEDED:
 254                 if (code != ICMP_EXC_TTL)
 255                         return 0;
 256                 break;
 257         }
 258
 259         err = -ENOENT;
 260
 261         read_lock(&ipip6_lock);
 262         t = ipip6_tunnel_lookup(iph->daddr, iph->saddr);
 263         if (t == NULL || t->parms.iph.daddr == 0)
 264                 goto out;
 265
 266         err = 0;
 267         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 268                 goto out;
 269
 270         if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
 271                 t->err_count++;
 272         else
 273                 t->err_count = 1;
 274         t->err_time = jiffies;
 275 out:
 276         read_unlock(&ipip6_lock);
 277         return err;
 278 #else
 279         struct iphdr *iph = (struct iphdr*)dp;
 280         int hlen = iph->ihl<<2;
 281         struct ipv6hdr *iph6;
 282         const int type = icmp_hdr(skb)->type;
 283         const int code = icmp_hdr(skb)->code;
 284         int rel_type = 0;
 285         int rel_code = 0;
 286         int rel_info = 0;
 287         struct sk_buff *skb2;
 288         struct rt6_info *rt6i;
 289
 290         if (len < hlen + sizeof(struct ipv6hdr))
 291                 return;
 292         iph6 = (struct ipv6hdr*)(dp + hlen);
 293
 294         switch (type) {
 295         default:
 296                 return;
 297         case ICMP_PARAMETERPROB:
 298                 if (icmp_hdr(skb)->un.gateway < hlen)
 299                         return;
 300
 301                 /* So... This guy found something strange INSIDE encapsulated
 302                    packet. Well, he is fool, but what can we do ?
 303                  */
 304                 rel_type = ICMPV6_PARAMPROB;
 305                 rel_info = icmp_hdr(skb)->un.gateway - hlen;
 306                 break;
 307
 308         case ICMP_DEST_UNREACH:
 309                 switch (code) {
 310                 case ICMP_SR_FAILED:
 311                 case ICMP_PORT_UNREACH:
 312                         /* Impossible event. */
 313                         return;
 314                 case ICMP_FRAG_NEEDED:
 315                         /* Too complicated case ... */
 316                         return;
 317                 default:
 318                         /* All others are translated to HOST_UNREACH.
 319                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 320                            I believe, it is just ether pollution. --ANK
 321                          */
 322                         rel_type = ICMPV6_DEST_UNREACH;
 323                         rel_code = ICMPV6_ADDR_UNREACH;
 324                         break;
 325                 }
 326                 break;
 327         case ICMP_TIME_EXCEEDED:
 328                 if (code != ICMP_EXC_TTL)
 329                         return;
 330                 rel_type = ICMPV6_TIME_EXCEED;
 331                 rel_code = ICMPV6_EXC_HOPLIMIT;
 332                 break;
 333         }
 334
 335         /* Prepare fake skb to feed it to icmpv6_send */
 336         skb2 = skb_clone(skb, GFP_ATOMIC);
 337         if (skb2 == NULL)
 338                 return 0;
 339         dst_release(skb2->dst);
 340         skb2->dst = NULL;
 341         skb_pull(skb2, skb->data - (u8*)iph6);
 342         skb_reset_network_header(skb2);
 343
 344         /* Try to guess incoming interface */
 345         rt6i = rt6_lookup(&iph6->saddr, NULL, NULL, 0);
 346         if (rt6i && rt6i->rt6i_dev) {
 347                 skb2->dev = rt6i->rt6i_dev;
 348
 349                 rt6i = rt6_lookup(&iph6->daddr, &iph6->saddr, NULL, 0);
 350
 351                 if (rt6i && rt6i->rt6i_dev && rt6i->rt6i_dev->type == ARPHRD_SIT) {
 352                         struct ip_tunnel *t = netdev_priv(rt6i->rt6i_dev);
 353                         if (rel_type == ICMPV6_TIME_EXCEED && t->parms.iph.ttl) {
 354                                 rel_type = ICMPV6_DEST_UNREACH;
 355                                 rel_code = ICMPV6_ADDR_UNREACH;
 356                         }
 357                         icmpv6_send(skb2, rel_type, rel_code, rel_info, skb2->dev);
 358                 }
 359         }
 360         kfree_skb(skb2);
 361         return 0;
 362 #endif
 363 }
 364
 365 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 366 {
 367         if (INET_ECN_is_ce(iph->tos))
 368                 IP6_ECN_set_ce(ipv6_hdr(skb));
 369 }
 370
 371 /* ISATAP (RFC4214) - check source address */
 372 static int
 373 isatap_srcok(struct sk_buff *skb, struct iphdr *iph, struct net_device *dev)
 374 {
 375         struct neighbour *neigh;
 376         struct dst_entry *dst;
 377         struct rt6_info *rt;
 378         struct flowi fl;
 379         struct in6_addr *addr6;
 380         struct in6_addr rtr;
 381         struct ipv6hdr *iph6;
 382         int ok = 0;
 383
 384         /* from onlink default router */
 385         ipv6_addr_set(&rtr,  htonl(0xFE800000), 0, 0, 0);
 386         ipv6_isatap_eui64(rtr.s6_addr + 8, iph->saddr);
 387         if ((rt = rt6_get_dflt_router(&rtr, dev))) {
 388                 dst_release(&rt->u.dst);
 389                 return 1;
 390         }
 391
 392         iph6 = ipv6_hdr(skb);
 393         memset(&fl, 0, sizeof(fl));
 394         fl.proto = iph6->nexthdr;
 395         ipv6_addr_copy(&fl.fl6_dst, &iph6->saddr);
 396         fl.oif = dev->ifindex;
 397         security_skb_classify_flow(skb, &fl);
 398
 399         dst = ip6_route_output(NULL, &fl);
 400         if (!dst->error && (dst->dev == dev) && (neigh = dst->neighbour)) {
 401
 402                 addr6 = (struct in6_addr*)&neigh->primary_key;
 403
 404                 /* from correct previous hop */
 405                 if (ipv6_addr_is_isatap(addr6) &&
 406                     (addr6->s6_addr32[3] == iph->saddr))
 407                         ok = 1;
 408         }
 409         dst_release(dst);
 410         return ok;
 411 }
 412
 413 static int ipip6_rcv(struct sk_buff *skb)
 414 {
 415         struct iphdr *iph;
 416         struct ip_tunnel *tunnel;
 417
 418         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 419                 goto out;
 420
 421         iph = ip_hdr(skb);
 422
 423         read_lock(&ipip6_lock);
 424         if ((tunnel = ipip6_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
 425                 secpath_reset(skb);
 426                 skb->mac_header = skb->network_header;
 427                 skb_reset_network_header(skb);
 428                 IPCB(skb)->flags = 0;
 429                 skb->protocol = htons(ETH_P_IPV6);
 430                 skb->pkt_type = PACKET_HOST;
 431
 432                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
 433                     !isatap_srcok(skb, iph, tunnel->dev)) {
 434                         tunnel->stat.rx_errors++;
 435                         read_unlock(&ipip6_lock);
 436                         kfree_skb(skb);
 437                         return 0;
 438                 }
 439                 tunnel->stat.rx_packets++;
 440                 tunnel->stat.rx_bytes += skb->len;
 441                 skb->dev = tunnel->dev;
 442                 dst_release(skb->dst);
 443                 skb->dst = NULL;
 444                 nf_reset(skb);
 445                 ipip6_ecn_decapsulate(iph, skb);
 446                 netif_rx(skb);
 447                 read_unlock(&ipip6_lock);
 448                 return 0;
 449         }
 450
 451         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 452         kfree_skb(skb);
 453         read_unlock(&ipip6_lock);
 454 out:
 455         return 0;
 456 }
 457
 458 /* Returns the embedded IPv4 address if the IPv6 address
 459    comes from 6to4 (RFC 3056) addr space */
 460
 461 static inline __be32 try_6to4(struct in6_addr *v6dst)
 462 {
 463         __be32 dst = 0;
 464
 465         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 466                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 467                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 468         }
 469         return dst;
 470 }
 471
 472 /*
 473  *      This function assumes it is being called from dev_queue_xmit()
 474  *      and that skb is filled properly by that function.
 475  */
 476
 477 static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 478 {
 479         struct ip_tunnel *tunnel = netdev_priv(dev);
 480         struct net_device_stats *stats = &tunnel->stat;
 481         struct iphdr  *tiph = &tunnel->parms.iph;
 482         struct ipv6hdr *iph6 = ipv6_hdr(skb);
 483         u8     tos = tunnel->parms.iph.tos;
 484         struct rtable *rt;                      /* Route to the other host */
 485         struct net_device *tdev;                        /* Device to other host */
 486         struct iphdr  *iph;                     /* Our new IP header */
 487         unsigned int max_headroom;              /* The extra header space needed */
 488         __be32 dst = tiph->daddr;
 489         int    mtu;
 490         struct in6_addr *addr6;
 491         int addr_type;
 492
 493         if (tunnel->recursion++) {
 494                 tunnel->stat.collisions++;
 495                 goto tx_error;
 496         }
 497
 498         if (skb->protocol != htons(ETH_P_IPV6))
 499                 goto tx_error;
 500
 501         /* ISATAP (RFC4214) - must come before 6to4 */
 502         if (dev->priv_flags & IFF_ISATAP) {
 503                 struct neighbour *neigh = NULL;
 504
 505                 if (skb->dst)
 506                         neigh = skb->dst->neighbour;
 507
 508                 if (neigh == NULL) {
 509                         if (net_ratelimit())
 510                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 511                         goto tx_error;
 512                 }
 513
 514                 addr6 = (struct in6_addr*)&neigh->primary_key;
 515                 addr_type = ipv6_addr_type(addr6);
 516
 517                 if ((addr_type & IPV6_ADDR_UNICAST) &&
 518                      ipv6_addr_is_isatap(addr6))
 519                         dst = addr6->s6_addr32[3];
 520                 else
 521                         goto tx_error;
 522         }
 523
 524         if (!dst)
 525                 dst = try_6to4(&iph6->daddr);
 526
 527         if (!dst) {
 528                 struct neighbour *neigh = NULL;
 529
 530                 if (skb->dst)
 531                         neigh = skb->dst->neighbour;
 532
 533                 if (neigh == NULL) {
 534                         if (net_ratelimit())
 535                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 536                         goto tx_error;
 537                 }
 538
 539                 addr6 = (struct in6_addr*)&neigh->primary_key;
 540                 addr_type = ipv6_addr_type(addr6);
 541
 542                 if (addr_type == IPV6_ADDR_ANY) {
 543                         addr6 = &ipv6_hdr(skb)->daddr;
 544                         addr_type = ipv6_addr_type(addr6);
 545                 }
 546
 547                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 548                         goto tx_error_icmp;
 549
 550                 dst = addr6->s6_addr32[3];
 551         }
 552
 553         {
 554                 struct flowi fl = { .nl_u = { .ip4_u =
 555                                               { .daddr = dst,
 556                                                 .saddr = tiph->saddr,
 557                                                 .tos = RT_TOS(tos) } },
 558                                     .oif = tunnel->parms.link,
 559                                     .proto = IPPROTO_IPV6 };
 560                 if (ip_route_output_key(&rt, &fl)) {
 561                         tunnel->stat.tx_carrier_errors++;
 562                         goto tx_error_icmp;
 563                 }
 564         }
 565         if (rt->rt_type != RTN_UNICAST) {
 566                 ip_rt_put(rt);
 567                 tunnel->stat.tx_carrier_errors++;
 568                 goto tx_error_icmp;
 569         }
 570         tdev = rt->u.dst.dev;
 571
 572         if (tdev == dev) {
 573                 ip_rt_put(rt);
 574                 tunnel->stat.collisions++;
 575                 goto tx_error;
 576         }
 577
 578         if (tiph->frag_off)
 579                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 580         else
 581                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 582
 583         if (mtu < 68) {
 584                 tunnel->stat.collisions++;
 585                 ip_rt_put(rt);
 586                 goto tx_error;
 587         }
 588         if (mtu < IPV6_MIN_MTU)
 589                 mtu = IPV6_MIN_MTU;
 590         if (tunnel->parms.iph.daddr && skb->dst)
 591                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 592
 593         if (skb->len > mtu) {
 594                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 595                 ip_rt_put(rt);
 596                 goto tx_error;
 597         }
 598
 599         if (tunnel->err_count > 0) {
 600                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 601                         tunnel->err_count--;
 602                         dst_link_failure(skb);
 603                 } else
 604                         tunnel->err_count = 0;
 605         }
 606
 607         /*
 608          * Okay, now see if we can stuff it in the buffer as-is.
 609          */
 610         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 611
 612         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 613             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 614                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 615                 if (!new_skb) {
 616                         ip_rt_put(rt);
 617                         stats->tx_dropped++;
 618                         dev_kfree_skb(skb);
 619                         tunnel->recursion--;
 620                         return 0;
 621                 }
 622                 if (skb->sk)
 623                         skb_set_owner_w(new_skb, skb->sk);
 624                 dev_kfree_skb(skb);
 625                 skb = new_skb;
 626                 iph6 = ipv6_hdr(skb);
 627         }
 628
 629         skb->transport_header = skb->network_header;
 630         skb_push(skb, sizeof(struct iphdr));
 631         skb_reset_network_header(skb);
 632         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 633         IPCB(skb)->flags = 0;
 634         dst_release(skb->dst);
 635         skb->dst = &rt->u.dst;
 636
 637         /*
 638          *      Push down and install the IPIP header.
 639          */
 640
 641         iph                     =       ip_hdr(skb);
 642         iph->version            =       4;
 643         iph->ihl                =       sizeof(struct iphdr)>>2;
 644         if (mtu > IPV6_MIN_MTU)
 645                 iph->frag_off   =       htons(IP_DF);
 646         else
 647                 iph->frag_off   =       0;
 648
 649         iph->protocol           =       IPPROTO_IPV6;
 650         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 651         iph->daddr              =       rt->rt_dst;
 652         iph->saddr              =       rt->rt_src;
 653
 654         if ((iph->ttl = tiph->ttl) == 0)
 655                 iph->ttl        =       iph6->hop_limit;
 656
 657         nf_reset(skb);
 658
 659         IPTUNNEL_XMIT();
 660         tunnel->recursion--;
 661         return 0;
 662
 663 tx_error_icmp:
 664         dst_link_failure(skb);
 665 tx_error:
 666         stats->tx_errors++;
 667         dev_kfree_skb(skb);
 668         tunnel->recursion--;
 669         return 0;
 670 }
 671
 672 static int
 673 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 674 {
 675         int err = 0;
 676         struct ip_tunnel_parm p;
 677         struct ip_tunnel *t;
 678
 679         switch (cmd) {
 680         case SIOCGETTUNNEL:
 681                 t = NULL;
 682                 if (dev == ipip6_fb_tunnel_dev) {
 683                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 684                                 err = -EFAULT;
 685                                 break;
 686                         }
 687                         t = ipip6_tunnel_locate(&p, 0);
 688                 }
 689                 if (t == NULL)
 690                         t = netdev_priv(dev);
 691                 memcpy(&p, &t->parms, sizeof(p));
 692                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 693                         err = -EFAULT;
 694                 break;
 695
 696         case SIOCADDTUNNEL:
 697         case SIOCCHGTUNNEL:
 698                 err = -EPERM;
 699                 if (!capable(CAP_NET_ADMIN))
 700                         goto done;
 701
 702                 err = -EFAULT;
 703                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 704                         goto done;
 705
 706                 err = -EINVAL;
 707                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 708                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 709                         goto done;
 710                 if (p.iph.ttl)
 711                         p.iph.frag_off |= htons(IP_DF);
 712
 713                 t = ipip6_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 714
 715                 if (dev != ipip6_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 716                         if (t != NULL) {
 717                                 if (t->dev != dev) {
 718                                         err = -EEXIST;
 719                                         break;
 720                                 }
 721                         } else {
 722                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 723                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 724                                         err = -EINVAL;
 725                                         break;
 726                                 }
 727                                 t = netdev_priv(dev);
 728                                 ipip6_tunnel_unlink(t);
 729                                 t->parms.iph.saddr = p.iph.saddr;
 730                                 t->parms.iph.daddr = p.iph.daddr;
 731                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 732                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 733                                 ipip6_tunnel_link(t);
 734                                 netdev_state_change(dev);
 735                         }
 736                 }
 737
 738                 if (t) {
 739                         err = 0;
 740                         if (cmd == SIOCCHGTUNNEL) {
 741                                 t->parms.iph.ttl = p.iph.ttl;
 742                                 t->parms.iph.tos = p.iph.tos;
 743                         }
 744                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 745                                 err = -EFAULT;
 746                 } else
 747                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 748                 break;
 749
 750         case SIOCDELTUNNEL:
 751                 err = -EPERM;
 752                 if (!capable(CAP_NET_ADMIN))
 753                         goto done;
 754
 755                 if (dev == ipip6_fb_tunnel_dev) {
 756                         err = -EFAULT;
 757                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 758                                 goto done;
 759                         err = -ENOENT;
 760                         if ((t = ipip6_tunnel_locate(&p, 0)) == NULL)
 761                                 goto done;
 762                         err = -EPERM;
 763                         if (t == netdev_priv(ipip6_fb_tunnel_dev))
 764                                 goto done;
 765                         dev = t->dev;
 766                 }
 767                 unregister_netdevice(dev);
 768                 err = 0;
 769                 break;
 770
 771         default:
 772                 err = -EINVAL;
 773         }
 774
 775 done:
 776         return err;
 777 }
 778
 779 static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev)
 780 {
 781         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
 782 }
 783
 784 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
 785 {
 786         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
 787                 return -EINVAL;
 788         dev->mtu = new_mtu;
 789         return 0;
 790 }
 791
 792 static void ipip6_tunnel_setup(struct net_device *dev)
 793 {
 794         dev->uninit             = ipip6_tunnel_uninit;
 795         dev->destructor         = free_netdev;
 796         dev->hard_start_xmit    = ipip6_tunnel_xmit;
 797         dev->get_stats          = ipip6_tunnel_get_stats;
 798         dev->do_ioctl           = ipip6_tunnel_ioctl;
 799         dev->change_mtu         = ipip6_tunnel_change_mtu;
 800
 801         dev->type               = ARPHRD_SIT;
 802         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
 803         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
 804         dev->flags              = IFF_NOARP;
 805         dev->iflink             = 0;
 806         dev->addr_len           = 4;
 807 }
 808
 809 static int ipip6_tunnel_init(struct net_device *dev)
 810 {
 811         struct net_device *tdev = NULL;
 812         struct ip_tunnel *tunnel;
 813         struct iphdr *iph;
 814
 815         tunnel = netdev_priv(dev);
 816         iph = &tunnel->parms.iph;
 817
 818         tunnel->dev = dev;
 819         strcpy(tunnel->parms.name, dev->name);
 820
 821         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 822         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 823
 824         if (iph->daddr) {
 825                 struct flowi fl = { .nl_u = { .ip4_u =
 826                                               { .daddr = iph->daddr,
 827                                                 .saddr = iph->saddr,
 828                                                 .tos = RT_TOS(iph->tos) } },
 829                                     .oif = tunnel->parms.link,
 830                                     .proto = IPPROTO_IPV6 };
 831                 struct rtable *rt;
 832                 if (!ip_route_output_key(&rt, &fl)) {
 833                         tdev = rt->u.dst.dev;
 834                         ip_rt_put(rt);
 835                 }
 836                 dev->flags |= IFF_POINTOPOINT;
 837         }
 838
 839         if (!tdev && tunnel->parms.link)
 840                 tdev = __dev_get_by_index(&init_net, tunnel->parms.link);
 841
 842         if (tdev) {
 843                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 844                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 845                 if (dev->mtu < IPV6_MIN_MTU)
 846                         dev->mtu = IPV6_MIN_MTU;
 847         }
 848         dev->iflink = tunnel->parms.link;
 849
 850         return 0;
 851 }
 852
 853 static int __init ipip6_fb_tunnel_init(struct net_device *dev)
 854 {
 855         struct ip_tunnel *tunnel = netdev_priv(dev);
 856         struct iphdr *iph = &tunnel->parms.iph;
 857
 858         tunnel->dev = dev;
 859         strcpy(tunnel->parms.name, dev->name);
 860
 861         iph->version            = 4;
 862         iph->protocol           = IPPROTO_IPV6;
 863         iph->ihl                = 5;
 864         iph->ttl                = 64;
 865
 866         dev_hold(dev);
 867         tunnels_wc[0]           = tunnel;
 868         return 0;
 869 }
 870
 871 static struct xfrm_tunnel sit_handler = {
 872         .handler        =       ipip6_rcv,
 873         .err_handler    =       ipip6_err,
 874         .priority       =       1,
 875 };
 876
 877 static void __exit sit_destroy_tunnels(void)
 878 {
 879         int prio;
 880
 881         for (prio = 1; prio < 4; prio++) {
 882                 int h;
 883                 for (h = 0; h < HASH_SIZE; h++) {
 884                         struct ip_tunnel *t;
 885                         while ((t = tunnels[prio][h]) != NULL)
 886                                 unregister_netdevice(t->dev);
 887                 }
 888         }
 889 }
 890
 891 static void __exit sit_cleanup(void)
 892 {
 893         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
 894
 895         rtnl_lock();
 896         sit_destroy_tunnels();
 897         unregister_netdevice(ipip6_fb_tunnel_dev);
 898         rtnl_unlock();
 899 }
 900
 901 static int __init sit_init(void)
 902 {
 903         int err;
 904
 905         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
 906
 907         if (xfrm4_tunnel_register(&sit_handler, AF_INET6) < 0) {
 908                 printk(KERN_INFO "sit init: Can't add protocol\n");
 909                 return -EAGAIN;
 910         }
 911
 912         ipip6_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
 913                                            ipip6_tunnel_setup);
 914         if (!ipip6_fb_tunnel_dev) {
 915                 err = -ENOMEM;
 916                 goto err1;
 917         }
 918
 919         ipip6_fb_tunnel_dev->init = ipip6_fb_tunnel_init;
 920
 921         if ((err =  register_netdev(ipip6_fb_tunnel_dev)))
 922                 goto err2;
 923
 924  out:
 925         return err;
 926  err2:
 927         free_netdev(ipip6_fb_tunnel_dev);
 928  err1:
 929         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
 930         goto out;
 931 }
 932
 933 module_init(sit_init);
 934 module_exit(sit_cleanup);
 935 MODULE_LICENSE("GPL");
 936 MODULE_ALIAS("sit0");