git.oblomov.eu Git - linux-2.6/blob - net/ipv6/sit.c

   1 /*
   2  *      IPv6 over IPv4 tunnel device - Simple Internet Transition (SIT)
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *      Changes:
  15  * Roger Venning <r.venning@telstra.com>:       6to4 support
  16  * Nate Thompson <nate@thebog.net>:             6to4 support
  17  * Fred Templin <fred.l.templin@boeing.com>:    isatap support
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/capability.h>
  22 #include <linux/errno.h>
  23 #include <linux/types.h>
  24 #include <linux/socket.h>
  25 #include <linux/sockios.h>
  26 #include <linux/net.h>
  27 #include <linux/in6.h>
  28 #include <linux/netdevice.h>
  29 #include <linux/if_arp.h>
  30 #include <linux/icmp.h>
  31 #include <asm/uaccess.h>
  32 #include <linux/init.h>
  33 #include <linux/netfilter_ipv4.h>
  34 #include <linux/if_ether.h>
  35
  36 #include <net/sock.h>
  37 #include <net/snmp.h>
  38
  39 #include <net/ipv6.h>
  40 #include <net/protocol.h>
  41 #include <net/transp_v6.h>
  42 #include <net/ip6_fib.h>
  43 #include <net/ip6_route.h>
  44 #include <net/ndisc.h>
  45 #include <net/addrconf.h>
  46 #include <net/ip.h>
  47 #include <net/udp.h>
  48 #include <net/icmp.h>
  49 #include <net/ipip.h>
  50 #include <net/inet_ecn.h>
  51 #include <net/xfrm.h>
  52 #include <net/dsfield.h>
  53 #include <net/net_namespace.h>
  54 #include <net/netns/generic.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 void ipip6_fb_tunnel_init(struct net_device *dev);
  66 static void ipip6_tunnel_init(struct net_device *dev);
  67 static void ipip6_tunnel_setup(struct net_device *dev);
  68
  69 static int sit_net_id;
  70 struct sit_net {
  71         struct ip_tunnel *tunnels_r_l[HASH_SIZE];
  72         struct ip_tunnel *tunnels_r[HASH_SIZE];
  73         struct ip_tunnel *tunnels_l[HASH_SIZE];
  74         struct ip_tunnel *tunnels_wc[1];
  75         struct ip_tunnel **tunnels[4];
  76
  77         struct net_device *fb_tunnel_dev;
  78 };
  79
  80 static DEFINE_RWLOCK(ipip6_lock);
  81
  82 static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,
  83                 __be32 remote, __be32 local)
  84 {
  85         unsigned h0 = HASH(remote);
  86         unsigned h1 = HASH(local);
  87         struct ip_tunnel *t;
  88         struct sit_net *sitn = net_generic(net, sit_net_id);
  89
  90         for (t = sitn->tunnels_r_l[h0^h1]; t; t = t->next) {
  91                 if (local == t->parms.iph.saddr &&
  92                     remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
  93                         return t;
  94         }
  95         for (t = sitn->tunnels_r[h0]; t; t = t->next) {
  96                 if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
  97                         return t;
  98         }
  99         for (t = sitn->tunnels_l[h1]; t; t = t->next) {
 100                 if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
 101                         return t;
 102         }
 103         if ((t = sitn->tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP))
 104                 return t;
 105         return NULL;
 106 }
 107
 108 static struct ip_tunnel **__ipip6_bucket(struct sit_net *sitn,
 109                 struct ip_tunnel_parm *parms)
 110 {
 111         __be32 remote = parms->iph.daddr;
 112         __be32 local = parms->iph.saddr;
 113         unsigned h = 0;
 114         int prio = 0;
 115
 116         if (remote) {
 117                 prio |= 2;
 118                 h ^= HASH(remote);
 119         }
 120         if (local) {
 121                 prio |= 1;
 122                 h ^= HASH(local);
 123         }
 124         return &sitn->tunnels[prio][h];
 125 }
 126
 127 static inline struct ip_tunnel **ipip6_bucket(struct sit_net *sitn,
 128                 struct ip_tunnel *t)
 129 {
 130         return __ipip6_bucket(sitn, &t->parms);
 131 }
 132
 133 static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
 134 {
 135         struct ip_tunnel **tp;
 136
 137         for (tp = ipip6_bucket(sitn, t); *tp; tp = &(*tp)->next) {
 138                 if (t == *tp) {
 139                         write_lock_bh(&ipip6_lock);
 140                         *tp = t->next;
 141                         write_unlock_bh(&ipip6_lock);
 142                         break;
 143                 }
 144         }
 145 }
 146
 147 static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
 148 {
 149         struct ip_tunnel **tp = ipip6_bucket(sitn, t);
 150
 151         t->next = *tp;
 152         write_lock_bh(&ipip6_lock);
 153         *tp = t;
 154         write_unlock_bh(&ipip6_lock);
 155 }
 156
 157 static struct ip_tunnel * ipip6_tunnel_locate(struct net *net,
 158                 struct ip_tunnel_parm *parms, int create)
 159 {
 160         __be32 remote = parms->iph.daddr;
 161         __be32 local = parms->iph.saddr;
 162         struct ip_tunnel *t, **tp, *nt;
 163         struct net_device *dev;
 164         char name[IFNAMSIZ];
 165         struct sit_net *sitn = net_generic(net, sit_net_id);
 166
 167         for (tp = __ipip6_bucket(sitn, parms); (t = *tp) != NULL; tp = &t->next) {
 168                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
 169                         return t;
 170         }
 171         if (!create)
 172                 goto failed;
 173
 174         if (parms->name[0])
 175                 strlcpy(name, parms->name, IFNAMSIZ);
 176         else
 177                 sprintf(name, "sit%%d");
 178
 179         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
 180         if (dev == NULL)
 181                 return NULL;
 182
 183         dev_net_set(dev, net);
 184
 185         if (strchr(name, '%')) {
 186                 if (dev_alloc_name(dev, name) < 0)
 187                         goto failed_free;
 188         }
 189
 190         nt = netdev_priv(dev);
 191         ipip6_tunnel_init(dev);
 192
 193         nt->parms = *parms;
 194
 195         if (parms->i_flags & SIT_ISATAP)
 196                 dev->priv_flags |= IFF_ISATAP;
 197
 198         if (register_netdevice(dev) < 0)
 199                 goto failed_free;
 200
 201         dev_hold(dev);
 202
 203         ipip6_tunnel_link(sitn, nt);
 204         return nt;
 205
 206 failed_free:
 207         free_netdev(dev);
 208 failed:
 209         return NULL;
 210 }
 211
 212 static struct ip_tunnel_prl_entry *
 213 __ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
 214 {
 215         struct ip_tunnel_prl_entry *p = (struct ip_tunnel_prl_entry *)NULL;
 216
 217         for (p = t->prl; p; p = p->next)
 218                 if (p->addr == addr)
 219                         break;
 220         return p;
 221
 222 }
 223
 224 static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
 225                                 struct ip_tunnel_prl __user *a)
 226 {
 227         struct ip_tunnel_prl kprl, *kp;
 228         struct ip_tunnel_prl_entry *prl;
 229         unsigned int cmax, c = 0, ca, len;
 230         int ret = 0;
 231
 232         if (copy_from_user(&kprl, a, sizeof(kprl)))
 233                 return -EFAULT;
 234         cmax = kprl.datalen / sizeof(kprl);
 235         if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
 236                 cmax = 1;
 237
 238         /* For simple GET or for root users,
 239          * we try harder to allocate.
 240          */
 241         kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
 242                 kcalloc(cmax, sizeof(*kp), GFP_KERNEL) :
 243                 NULL;
 244
 245         read_lock(&ipip6_lock);
 246
 247         ca = t->prl_count < cmax ? t->prl_count : cmax;
 248
 249         if (!kp) {
 250                 /* We don't try hard to allocate much memory for
 251                  * non-root users.
 252                  * For root users, retry allocating enough memory for
 253                  * the answer.
 254                  */
 255                 kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC);
 256                 if (!kp) {
 257                         ret = -ENOMEM;
 258                         goto out;
 259                 }
 260         }
 261
 262         c = 0;
 263         for (prl = t->prl; prl; prl = prl->next) {
 264                 if (c > cmax)
 265                         break;
 266                 if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
 267                         continue;
 268                 kp[c].addr = prl->addr;
 269                 kp[c].flags = prl->flags;
 270                 c++;
 271                 if (kprl.addr != htonl(INADDR_ANY))
 272                         break;
 273         }
 274 out:
 275         read_unlock(&ipip6_lock);
 276
 277         len = sizeof(*kp) * c;
 278         ret = 0;
 279         if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
 280                 ret = -EFAULT;
 281
 282         kfree(kp);
 283
 284         return ret;
 285 }
 286
 287 static int
 288 ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
 289 {
 290         struct ip_tunnel_prl_entry *p;
 291         int err = 0;
 292
 293         if (a->addr == htonl(INADDR_ANY))
 294                 return -EINVAL;
 295
 296         write_lock(&ipip6_lock);
 297
 298         for (p = t->prl; p; p = p->next) {
 299                 if (p->addr == a->addr) {
 300                         if (chg)
 301                                 goto update;
 302                         err = -EEXIST;
 303                         goto out;
 304                 }
 305         }
 306
 307         if (chg) {
 308                 err = -ENXIO;
 309                 goto out;
 310         }
 311
 312         p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
 313         if (!p) {
 314                 err = -ENOBUFS;
 315                 goto out;
 316         }
 317
 318         p->next = t->prl;
 319         t->prl = p;
 320         t->prl_count++;
 321 update:
 322         p->addr = a->addr;
 323         p->flags = a->flags;
 324 out:
 325         write_unlock(&ipip6_lock);
 326         return err;
 327 }
 328
 329 static int
 330 ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
 331 {
 332         struct ip_tunnel_prl_entry *x, **p;
 333         int err = 0;
 334
 335         write_lock(&ipip6_lock);
 336
 337         if (a && a->addr != htonl(INADDR_ANY)) {
 338                 for (p = &t->prl; *p; p = &(*p)->next) {
 339                         if ((*p)->addr == a->addr) {
 340                                 x = *p;
 341                                 *p = x->next;
 342                                 kfree(x);
 343                                 t->prl_count--;
 344                                 goto out;
 345                         }
 346                 }
 347                 err = -ENXIO;
 348         } else {
 349                 while (t->prl) {
 350                         x = t->prl;
 351                         t->prl = t->prl->next;
 352                         kfree(x);
 353                         t->prl_count--;
 354                 }
 355         }
 356 out:
 357         write_unlock(&ipip6_lock);
 358         return 0;
 359 }
 360
 361 static int
 362 isatap_chksrc(struct sk_buff *skb, struct iphdr *iph, struct ip_tunnel *t)
 363 {
 364         struct ip_tunnel_prl_entry *p;
 365         int ok = 1;
 366
 367         read_lock(&ipip6_lock);
 368         p = __ipip6_tunnel_locate_prl(t, iph->saddr);
 369         if (p) {
 370                 if (p->flags & PRL_DEFAULT)
 371                         skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
 372                 else
 373                         skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
 374         } else {
 375                 struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
 376                 if (ipv6_addr_is_isatap(addr6) &&
 377                     (addr6->s6_addr32[3] == iph->saddr) &&
 378                     ipv6_chk_prefix(addr6, t->dev))
 379                         skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
 380                 else
 381                         ok = 0;
 382         }
 383         read_unlock(&ipip6_lock);
 384         return ok;
 385 }
 386
 387 static void ipip6_tunnel_uninit(struct net_device *dev)
 388 {
 389         struct net *net = dev_net(dev);
 390         struct sit_net *sitn = net_generic(net, sit_net_id);
 391
 392         if (dev == sitn->fb_tunnel_dev) {
 393                 write_lock_bh(&ipip6_lock);
 394                 sitn->tunnels_wc[0] = NULL;
 395                 write_unlock_bh(&ipip6_lock);
 396                 dev_put(dev);
 397         } else {
 398                 ipip6_tunnel_unlink(sitn, netdev_priv(dev));
 399                 ipip6_tunnel_del_prl(netdev_priv(dev), NULL);
 400                 dev_put(dev);
 401         }
 402 }
 403
 404
 405 static int ipip6_err(struct sk_buff *skb, u32 info)
 406 {
 407
 408 /* All the routers (except for Linux) return only
 409    8 bytes of packet payload. It means, that precise relaying of
 410    ICMP in the real Internet is absolutely infeasible.
 411  */
 412         struct iphdr *iph = (struct iphdr*)skb->data;
 413         const int type = icmp_hdr(skb)->type;
 414         const int code = icmp_hdr(skb)->code;
 415         struct ip_tunnel *t;
 416         int err;
 417
 418         switch (type) {
 419         default:
 420         case ICMP_PARAMETERPROB:
 421                 return 0;
 422
 423         case ICMP_DEST_UNREACH:
 424                 switch (code) {
 425                 case ICMP_SR_FAILED:
 426                 case ICMP_PORT_UNREACH:
 427                         /* Impossible event. */
 428                         return 0;
 429                 case ICMP_FRAG_NEEDED:
 430                         /* Soft state for pmtu is maintained by IP core. */
 431                         return 0;
 432                 default:
 433                         /* All others are translated to HOST_UNREACH.
 434                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 435                            I believe they are just ether pollution. --ANK
 436                          */
 437                         break;
 438                 }
 439                 break;
 440         case ICMP_TIME_EXCEEDED:
 441                 if (code != ICMP_EXC_TTL)
 442                         return 0;
 443                 break;
 444         }
 445
 446         err = -ENOENT;
 447
 448         read_lock(&ipip6_lock);
 449         t = ipip6_tunnel_lookup(dev_net(skb->dev), iph->daddr, iph->saddr);
 450         if (t == NULL || t->parms.iph.daddr == 0)
 451                 goto out;
 452
 453         err = 0;
 454         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 455                 goto out;
 456
 457         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
 458                 t->err_count++;
 459         else
 460                 t->err_count = 1;
 461         t->err_time = jiffies;
 462 out:
 463         read_unlock(&ipip6_lock);
 464         return err;
 465 }
 466
 467 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 468 {
 469         if (INET_ECN_is_ce(iph->tos))
 470                 IP6_ECN_set_ce(ipv6_hdr(skb));
 471 }
 472
 473 static int ipip6_rcv(struct sk_buff *skb)
 474 {
 475         struct iphdr *iph;
 476         struct ip_tunnel *tunnel;
 477
 478         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 479                 goto out;
 480
 481         iph = ip_hdr(skb);
 482
 483         read_lock(&ipip6_lock);
 484         if ((tunnel = ipip6_tunnel_lookup(dev_net(skb->dev),
 485                                         iph->saddr, iph->daddr)) != NULL) {
 486                 secpath_reset(skb);
 487                 skb->mac_header = skb->network_header;
 488                 skb_reset_network_header(skb);
 489                 IPCB(skb)->flags = 0;
 490                 skb->protocol = htons(ETH_P_IPV6);
 491                 skb->pkt_type = PACKET_HOST;
 492
 493                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
 494                     !isatap_chksrc(skb, iph, tunnel)) {
 495                         tunnel->dev->stats.rx_errors++;
 496                         read_unlock(&ipip6_lock);
 497                         kfree_skb(skb);
 498                         return 0;
 499                 }
 500                 tunnel->dev->stats.rx_packets++;
 501                 tunnel->dev->stats.rx_bytes += skb->len;
 502                 skb->dev = tunnel->dev;
 503                 dst_release(skb->dst);
 504                 skb->dst = NULL;
 505                 nf_reset(skb);
 506                 ipip6_ecn_decapsulate(iph, skb);
 507                 netif_rx(skb);
 508                 read_unlock(&ipip6_lock);
 509                 return 0;
 510         }
 511
 512         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 513         read_unlock(&ipip6_lock);
 514 out:
 515         kfree_skb(skb);
 516         return 0;
 517 }
 518
 519 /* Returns the embedded IPv4 address if the IPv6 address
 520    comes from 6to4 (RFC 3056) addr space */
 521
 522 static inline __be32 try_6to4(struct in6_addr *v6dst)
 523 {
 524         __be32 dst = 0;
 525
 526         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 527                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 528                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 529         }
 530         return dst;
 531 }
 532
 533 /*
 534  *      This function assumes it is being called from dev_queue_xmit()
 535  *      and that skb is filled properly by that function.
 536  */
 537
 538 static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 539 {
 540         struct ip_tunnel *tunnel = netdev_priv(dev);
 541         struct net_device_stats *stats = &tunnel->dev->stats;
 542         struct iphdr  *tiph = &tunnel->parms.iph;
 543         struct ipv6hdr *iph6 = ipv6_hdr(skb);
 544         u8     tos = tunnel->parms.iph.tos;
 545         struct rtable *rt;                      /* Route to the other host */
 546         struct net_device *tdev;                        /* Device to other host */
 547         struct iphdr  *iph;                     /* Our new IP header */
 548         unsigned int max_headroom;              /* The extra header space needed */
 549         __be32 dst = tiph->daddr;
 550         int    mtu;
 551         struct in6_addr *addr6;
 552         int addr_type;
 553
 554         if (tunnel->recursion++) {
 555                 stats->collisions++;
 556                 goto tx_error;
 557         }
 558
 559         if (skb->protocol != htons(ETH_P_IPV6))
 560                 goto tx_error;
 561
 562         /* ISATAP (RFC4214) - must come before 6to4 */
 563         if (dev->priv_flags & IFF_ISATAP) {
 564                 struct neighbour *neigh = NULL;
 565
 566                 if (skb->dst)
 567                         neigh = skb->dst->neighbour;
 568
 569                 if (neigh == NULL) {
 570                         if (net_ratelimit())
 571                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 572                         goto tx_error;
 573                 }
 574
 575                 addr6 = (struct in6_addr*)&neigh->primary_key;
 576                 addr_type = ipv6_addr_type(addr6);
 577
 578                 if ((addr_type & IPV6_ADDR_UNICAST) &&
 579                      ipv6_addr_is_isatap(addr6))
 580                         dst = addr6->s6_addr32[3];
 581                 else
 582                         goto tx_error;
 583         }
 584
 585         if (!dst)
 586                 dst = try_6to4(&iph6->daddr);
 587
 588         if (!dst) {
 589                 struct neighbour *neigh = NULL;
 590
 591                 if (skb->dst)
 592                         neigh = skb->dst->neighbour;
 593
 594                 if (neigh == NULL) {
 595                         if (net_ratelimit())
 596                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 597                         goto tx_error;
 598                 }
 599
 600                 addr6 = (struct in6_addr*)&neigh->primary_key;
 601                 addr_type = ipv6_addr_type(addr6);
 602
 603                 if (addr_type == IPV6_ADDR_ANY) {
 604                         addr6 = &ipv6_hdr(skb)->daddr;
 605                         addr_type = ipv6_addr_type(addr6);
 606                 }
 607
 608                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 609                         goto tx_error_icmp;
 610
 611                 dst = addr6->s6_addr32[3];
 612         }
 613
 614         {
 615                 struct flowi fl = { .nl_u = { .ip4_u =
 616                                               { .daddr = dst,
 617                                                 .saddr = tiph->saddr,
 618                                                 .tos = RT_TOS(tos) } },
 619                                     .oif = tunnel->parms.link,
 620                                     .proto = IPPROTO_IPV6 };
 621                 if (ip_route_output_key(dev_net(dev), &rt, &fl)) {
 622                         stats->tx_carrier_errors++;
 623                         goto tx_error_icmp;
 624                 }
 625         }
 626         if (rt->rt_type != RTN_UNICAST) {
 627                 ip_rt_put(rt);
 628                 stats->tx_carrier_errors++;
 629                 goto tx_error_icmp;
 630         }
 631         tdev = rt->u.dst.dev;
 632
 633         if (tdev == dev) {
 634                 ip_rt_put(rt);
 635                 stats->collisions++;
 636                 goto tx_error;
 637         }
 638
 639         if (tiph->frag_off)
 640                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 641         else
 642                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 643
 644         if (mtu < 68) {
 645                 stats->collisions++;
 646                 ip_rt_put(rt);
 647                 goto tx_error;
 648         }
 649         if (mtu < IPV6_MIN_MTU)
 650                 mtu = IPV6_MIN_MTU;
 651         if (tunnel->parms.iph.daddr && skb->dst)
 652                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 653
 654         if (skb->len > mtu) {
 655                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 656                 ip_rt_put(rt);
 657                 goto tx_error;
 658         }
 659
 660         if (tunnel->err_count > 0) {
 661                 if (time_before(jiffies,
 662                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
 663                         tunnel->err_count--;
 664                         dst_link_failure(skb);
 665                 } else
 666                         tunnel->err_count = 0;
 667         }
 668
 669         /*
 670          * Okay, now see if we can stuff it in the buffer as-is.
 671          */
 672         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 673
 674         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 675             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 676                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 677                 if (!new_skb) {
 678                         ip_rt_put(rt);
 679                         stats->tx_dropped++;
 680                         dev_kfree_skb(skb);
 681                         tunnel->recursion--;
 682                         return 0;
 683                 }
 684                 if (skb->sk)
 685                         skb_set_owner_w(new_skb, skb->sk);
 686                 dev_kfree_skb(skb);
 687                 skb = new_skb;
 688                 iph6 = ipv6_hdr(skb);
 689         }
 690
 691         skb->transport_header = skb->network_header;
 692         skb_push(skb, sizeof(struct iphdr));
 693         skb_reset_network_header(skb);
 694         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 695         IPCB(skb)->flags = 0;
 696         dst_release(skb->dst);
 697         skb->dst = &rt->u.dst;
 698
 699         /*
 700          *      Push down and install the IPIP header.
 701          */
 702
 703         iph                     =       ip_hdr(skb);
 704         iph->version            =       4;
 705         iph->ihl                =       sizeof(struct iphdr)>>2;
 706         if (mtu > IPV6_MIN_MTU)
 707                 iph->frag_off   =       htons(IP_DF);
 708         else
 709                 iph->frag_off   =       0;
 710
 711         iph->protocol           =       IPPROTO_IPV6;
 712         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 713         iph->daddr              =       rt->rt_dst;
 714         iph->saddr              =       rt->rt_src;
 715
 716         if ((iph->ttl = tiph->ttl) == 0)
 717                 iph->ttl        =       iph6->hop_limit;
 718
 719         nf_reset(skb);
 720
 721         IPTUNNEL_XMIT();
 722         tunnel->recursion--;
 723         return 0;
 724
 725 tx_error_icmp:
 726         dst_link_failure(skb);
 727 tx_error:
 728         stats->tx_errors++;
 729         dev_kfree_skb(skb);
 730         tunnel->recursion--;
 731         return 0;
 732 }
 733
 734 static void ipip6_tunnel_bind_dev(struct net_device *dev)
 735 {
 736         struct net_device *tdev = NULL;
 737         struct ip_tunnel *tunnel;
 738         struct iphdr *iph;
 739
 740         tunnel = netdev_priv(dev);
 741         iph = &tunnel->parms.iph;
 742
 743         if (iph->daddr) {
 744                 struct flowi fl = { .nl_u = { .ip4_u =
 745                                               { .daddr = iph->daddr,
 746                                                 .saddr = iph->saddr,
 747                                                 .tos = RT_TOS(iph->tos) } },
 748                                     .oif = tunnel->parms.link,
 749                                     .proto = IPPROTO_IPV6 };
 750                 struct rtable *rt;
 751                 if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 752                         tdev = rt->u.dst.dev;
 753                         ip_rt_put(rt);
 754                 }
 755                 dev->flags |= IFF_POINTOPOINT;
 756         }
 757
 758         if (!tdev && tunnel->parms.link)
 759                 tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);
 760
 761         if (tdev) {
 762                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 763                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 764                 if (dev->mtu < IPV6_MIN_MTU)
 765                         dev->mtu = IPV6_MIN_MTU;
 766         }
 767         dev->iflink = tunnel->parms.link;
 768 }
 769
 770 static int
 771 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 772 {
 773         int err = 0;
 774         struct ip_tunnel_parm p;
 775         struct ip_tunnel_prl prl;
 776         struct ip_tunnel *t;
 777         struct net *net = dev_net(dev);
 778         struct sit_net *sitn = net_generic(net, sit_net_id);
 779
 780         switch (cmd) {
 781         case SIOCGETTUNNEL:
 782                 t = NULL;
 783                 if (dev == sitn->fb_tunnel_dev) {
 784                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 785                                 err = -EFAULT;
 786                                 break;
 787                         }
 788                         t = ipip6_tunnel_locate(net, &p, 0);
 789                 }
 790                 if (t == NULL)
 791                         t = netdev_priv(dev);
 792                 memcpy(&p, &t->parms, sizeof(p));
 793                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 794                         err = -EFAULT;
 795                 break;
 796
 797         case SIOCADDTUNNEL:
 798         case SIOCCHGTUNNEL:
 799                 err = -EPERM;
 800                 if (!capable(CAP_NET_ADMIN))
 801                         goto done;
 802
 803                 err = -EFAULT;
 804                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 805                         goto done;
 806
 807                 err = -EINVAL;
 808                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 809                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 810                         goto done;
 811                 if (p.iph.ttl)
 812                         p.iph.frag_off |= htons(IP_DF);
 813
 814                 t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
 815
 816                 if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 817                         if (t != NULL) {
 818                                 if (t->dev != dev) {
 819                                         err = -EEXIST;
 820                                         break;
 821                                 }
 822                         } else {
 823                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 824                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 825                                         err = -EINVAL;
 826                                         break;
 827                                 }
 828                                 t = netdev_priv(dev);
 829                                 ipip6_tunnel_unlink(sitn, t);
 830                                 t->parms.iph.saddr = p.iph.saddr;
 831                                 t->parms.iph.daddr = p.iph.daddr;
 832                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 833                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 834                                 ipip6_tunnel_link(sitn, t);
 835                                 netdev_state_change(dev);
 836                         }
 837                 }
 838
 839                 if (t) {
 840                         err = 0;
 841                         if (cmd == SIOCCHGTUNNEL) {
 842                                 t->parms.iph.ttl = p.iph.ttl;
 843                                 t->parms.iph.tos = p.iph.tos;
 844                                 if (t->parms.link != p.link) {
 845                                         t->parms.link = p.link;
 846                                         ipip6_tunnel_bind_dev(dev);
 847                                         netdev_state_change(dev);
 848                                 }
 849                         }
 850                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 851                                 err = -EFAULT;
 852                 } else
 853                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 854                 break;
 855
 856         case SIOCDELTUNNEL:
 857                 err = -EPERM;
 858                 if (!capable(CAP_NET_ADMIN))
 859                         goto done;
 860
 861                 if (dev == sitn->fb_tunnel_dev) {
 862                         err = -EFAULT;
 863                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 864                                 goto done;
 865                         err = -ENOENT;
 866                         if ((t = ipip6_tunnel_locate(net, &p, 0)) == NULL)
 867                                 goto done;
 868                         err = -EPERM;
 869                         if (t == netdev_priv(sitn->fb_tunnel_dev))
 870                                 goto done;
 871                         dev = t->dev;
 872                 }
 873                 unregister_netdevice(dev);
 874                 err = 0;
 875                 break;
 876
 877         case SIOCGETPRL:
 878                 err = -EINVAL;
 879                 if (dev == sitn->fb_tunnel_dev)
 880                         goto done;
 881                 err = -ENOENT;
 882                 if (!(t = netdev_priv(dev)))
 883                         goto done;
 884                 err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
 885                 break;
 886
 887         case SIOCADDPRL:
 888         case SIOCDELPRL:
 889         case SIOCCHGPRL:
 890                 err = -EPERM;
 891                 if (!capable(CAP_NET_ADMIN))
 892                         goto done;
 893                 err = -EINVAL;
 894                 if (dev == sitn->fb_tunnel_dev)
 895                         goto done;
 896                 err = -EFAULT;
 897                 if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
 898                         goto done;
 899                 err = -ENOENT;
 900                 if (!(t = netdev_priv(dev)))
 901                         goto done;
 902
 903                 switch (cmd) {
 904                 case SIOCDELPRL:
 905                         err = ipip6_tunnel_del_prl(t, &prl);
 906                         break;
 907                 case SIOCADDPRL:
 908                 case SIOCCHGPRL:
 909                         err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
 910                         break;
 911                 }
 912                 netdev_state_change(dev);
 913                 break;
 914
 915         default:
 916                 err = -EINVAL;
 917         }
 918
 919 done:
 920         return err;
 921 }
 922
 923 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
 924 {
 925         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
 926                 return -EINVAL;
 927         dev->mtu = new_mtu;
 928         return 0;
 929 }
 930
 931 static const struct net_device_ops ipip6_netdev_ops = {
 932         .ndo_uninit     = ipip6_tunnel_uninit,
 933         .ndo_start_xmit = ipip6_tunnel_xmit,
 934         .ndo_do_ioctl   = ipip6_tunnel_ioctl,
 935         .ndo_change_mtu = ipip6_tunnel_change_mtu,
 936 };
 937
 938 static void ipip6_tunnel_setup(struct net_device *dev)
 939 {
 940         dev->netdev_ops         = &ipip6_netdev_ops;
 941         dev->destructor         = free_netdev;
 942
 943         dev->type               = ARPHRD_SIT;
 944         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
 945         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
 946         dev->flags              = IFF_NOARP;
 947         dev->iflink             = 0;
 948         dev->addr_len           = 4;
 949         dev->features           |= NETIF_F_NETNS_LOCAL;
 950 }
 951
 952 static void ipip6_tunnel_init(struct net_device *dev)
 953 {
 954         struct ip_tunnel *tunnel = netdev_priv(dev);
 955
 956         tunnel->dev = dev;
 957         strcpy(tunnel->parms.name, dev->name);
 958
 959         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 960         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 961
 962         ipip6_tunnel_bind_dev(dev);
 963 }
 964
 965 static void ipip6_fb_tunnel_init(struct net_device *dev)
 966 {
 967         struct ip_tunnel *tunnel = netdev_priv(dev);
 968         struct iphdr *iph = &tunnel->parms.iph;
 969         struct net *net = dev_net(dev);
 970         struct sit_net *sitn = net_generic(net, sit_net_id);
 971
 972         tunnel->dev = dev;
 973         strcpy(tunnel->parms.name, dev->name);
 974
 975         iph->version            = 4;
 976         iph->protocol           = IPPROTO_IPV6;
 977         iph->ihl                = 5;
 978         iph->ttl                = 64;
 979
 980         dev_hold(dev);
 981         sitn->tunnels_wc[0]     = tunnel;
 982 }
 983
 984 static struct xfrm_tunnel sit_handler = {
 985         .handler        =       ipip6_rcv,
 986         .err_handler    =       ipip6_err,
 987         .priority       =       1,
 988 };
 989
 990 static void sit_destroy_tunnels(struct sit_net *sitn)
 991 {
 992         int prio;
 993
 994         for (prio = 1; prio < 4; prio++) {
 995                 int h;
 996                 for (h = 0; h < HASH_SIZE; h++) {
 997                         struct ip_tunnel *t;
 998                         while ((t = sitn->tunnels[prio][h]) != NULL)
 999                                 unregister_netdevice(t->dev);
1000                 }
1001         }
1002 }
1003
1004 static int sit_init_net(struct net *net)
1005 {
1006         int err;
1007         struct sit_net *sitn;
1008
1009         err = -ENOMEM;
1010         sitn = kzalloc(sizeof(struct sit_net), GFP_KERNEL);
1011         if (sitn == NULL)
1012                 goto err_alloc;
1013
1014         err = net_assign_generic(net, sit_net_id, sitn);
1015         if (err < 0)
1016                 goto err_assign;
1017
1018         sitn->tunnels[0] = sitn->tunnels_wc;
1019         sitn->tunnels[1] = sitn->tunnels_l;
1020         sitn->tunnels[2] = sitn->tunnels_r;
1021         sitn->tunnels[3] = sitn->tunnels_r_l;
1022
1023         sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
1024                                            ipip6_tunnel_setup);
1025         if (!sitn->fb_tunnel_dev) {
1026                 err = -ENOMEM;
1027                 goto err_alloc_dev;
1028         }
1029         dev_net_set(sitn->fb_tunnel_dev, net);
1030
1031         ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
1032
1033         if ((err = register_netdev(sitn->fb_tunnel_dev)))
1034                 goto err_reg_dev;
1035
1036         return 0;
1037
1038 err_reg_dev:
1039         dev_put(sitn->fb_tunnel_dev);
1040         free_netdev(sitn->fb_tunnel_dev);
1041 err_alloc_dev:
1042         /* nothing */
1043 err_assign:
1044         kfree(sitn);
1045 err_alloc:
1046         return err;
1047 }
1048
1049 static void sit_exit_net(struct net *net)
1050 {
1051         struct sit_net *sitn;
1052
1053         sitn = net_generic(net, sit_net_id);
1054         rtnl_lock();
1055         sit_destroy_tunnels(sitn);
1056         unregister_netdevice(sitn->fb_tunnel_dev);
1057         rtnl_unlock();
1058         kfree(sitn);
1059 }
1060
1061 static struct pernet_operations sit_net_ops = {
1062         .init = sit_init_net,
1063         .exit = sit_exit_net,
1064 };
1065
1066 static void __exit sit_cleanup(void)
1067 {
1068         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1069
1070         unregister_pernet_gen_device(sit_net_id, &sit_net_ops);
1071 }
1072
1073 static int __init sit_init(void)
1074 {
1075         int err;
1076
1077         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
1078
1079         if (xfrm4_tunnel_register(&sit_handler, AF_INET6) < 0) {
1080                 printk(KERN_INFO "sit init: Can't add protocol\n");
1081                 return -EAGAIN;
1082         }
1083
1084         err = register_pernet_gen_device(&sit_net_id, &sit_net_ops);
1085         if (err < 0)
1086                 xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1087
1088         return err;
1089 }
1090
1091 module_init(sit_init);
1092 module_exit(sit_cleanup);
1093 MODULE_LICENSE("GPL");
1094 MODULE_ALIAS("sit0");