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 <linux/slab.h>
  32 #include <asm/uaccess.h>
  33 #include <linux/init.h>
  34 #include <linux/netfilter_ipv4.h>
  35 #include <linux/if_ether.h>
  36
  37 #include <net/sock.h>
  38 #include <net/snmp.h>
  39
  40 #include <net/ipv6.h>
  41 #include <net/protocol.h>
  42 #include <net/transp_v6.h>
  43 #include <net/ip6_fib.h>
  44 #include <net/ip6_route.h>
  45 #include <net/ndisc.h>
  46 #include <net/addrconf.h>
  47 #include <net/ip.h>
  48 #include <net/udp.h>
  49 #include <net/icmp.h>
  50 #include <net/ipip.h>
  51 #include <net/inet_ecn.h>
  52 #include <net/xfrm.h>
  53 #include <net/dsfield.h>
  54 #include <net/net_namespace.h>
  55 #include <net/netns/generic.h>
  56
  57 /*
  58    This version of net/ipv6/sit.c is cloned of net/ipv4/ip_gre.c
  59
  60    For comments look at net/ipv4/ip_gre.c --ANK
  61  */
  62
  63 #define HASH_SIZE  16
  64 #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
  65
  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 __read_mostly;
  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 /*
  81  * Locking : hash tables are protected by RCU and a spinlock
  82  */
  83 static DEFINE_SPINLOCK(ipip6_lock);
  84
  85 #define for_each_ip_tunnel_rcu(start) \
  86         for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
  87
  88 /*
  89  * Must be invoked with rcu_read_lock
  90  */
  91 static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,
  92                 struct net_device *dev, __be32 remote, __be32 local)
  93 {
  94         unsigned h0 = HASH(remote);
  95         unsigned h1 = HASH(local);
  96         struct ip_tunnel *t;
  97         struct sit_net *sitn = net_generic(net, sit_net_id);
  98
  99         for_each_ip_tunnel_rcu(sitn->tunnels_r_l[h0 ^ h1]) {
 100                 if (local == t->parms.iph.saddr &&
 101                     remote == t->parms.iph.daddr &&
 102                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 103                     (t->dev->flags & IFF_UP))
 104                         return t;
 105         }
 106         for_each_ip_tunnel_rcu(sitn->tunnels_r[h0]) {
 107                 if (remote == t->parms.iph.daddr &&
 108                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 109                     (t->dev->flags & IFF_UP))
 110                         return t;
 111         }
 112         for_each_ip_tunnel_rcu(sitn->tunnels_l[h1]) {
 113                 if (local == t->parms.iph.saddr &&
 114                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 115                     (t->dev->flags & IFF_UP))
 116                         return t;
 117         }
 118         t = rcu_dereference(sitn->tunnels_wc[0]);
 119         if ((t != NULL) && (t->dev->flags & IFF_UP))
 120                 return t;
 121         return NULL;
 122 }
 123
 124 static struct ip_tunnel **__ipip6_bucket(struct sit_net *sitn,
 125                 struct ip_tunnel_parm *parms)
 126 {
 127         __be32 remote = parms->iph.daddr;
 128         __be32 local = parms->iph.saddr;
 129         unsigned h = 0;
 130         int prio = 0;
 131
 132         if (remote) {
 133                 prio |= 2;
 134                 h ^= HASH(remote);
 135         }
 136         if (local) {
 137                 prio |= 1;
 138                 h ^= HASH(local);
 139         }
 140         return &sitn->tunnels[prio][h];
 141 }
 142
 143 static inline struct ip_tunnel **ipip6_bucket(struct sit_net *sitn,
 144                 struct ip_tunnel *t)
 145 {
 146         return __ipip6_bucket(sitn, &t->parms);
 147 }
 148
 149 static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
 150 {
 151         struct ip_tunnel **tp;
 152
 153         for (tp = ipip6_bucket(sitn, t); *tp; tp = &(*tp)->next) {
 154                 if (t == *tp) {
 155                         spin_lock_bh(&ipip6_lock);
 156                         *tp = t->next;
 157                         spin_unlock_bh(&ipip6_lock);
 158                         break;
 159                 }
 160         }
 161 }
 162
 163 static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
 164 {
 165         struct ip_tunnel **tp = ipip6_bucket(sitn, t);
 166
 167         spin_lock_bh(&ipip6_lock);
 168         t->next = *tp;
 169         rcu_assign_pointer(*tp, t);
 170         spin_unlock_bh(&ipip6_lock);
 171 }
 172
 173 static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
 174 {
 175 #ifdef CONFIG_IPV6_SIT_6RD
 176         struct ip_tunnel *t = netdev_priv(dev);
 177
 178         if (t->dev == sitn->fb_tunnel_dev) {
 179                 ipv6_addr_set(&t->ip6rd.prefix, htonl(0x20020000), 0, 0, 0);
 180                 t->ip6rd.relay_prefix = 0;
 181                 t->ip6rd.prefixlen = 16;
 182                 t->ip6rd.relay_prefixlen = 0;
 183         } else {
 184                 struct ip_tunnel *t0 = netdev_priv(sitn->fb_tunnel_dev);
 185                 memcpy(&t->ip6rd, &t0->ip6rd, sizeof(t->ip6rd));
 186         }
 187 #endif
 188 }
 189
 190 static struct ip_tunnel * ipip6_tunnel_locate(struct net *net,
 191                 struct ip_tunnel_parm *parms, int create)
 192 {
 193         __be32 remote = parms->iph.daddr;
 194         __be32 local = parms->iph.saddr;
 195         struct ip_tunnel *t, **tp, *nt;
 196         struct net_device *dev;
 197         char name[IFNAMSIZ];
 198         struct sit_net *sitn = net_generic(net, sit_net_id);
 199
 200         for (tp = __ipip6_bucket(sitn, parms); (t = *tp) != NULL; tp = &t->next) {
 201                 if (local == t->parms.iph.saddr &&
 202                     remote == t->parms.iph.daddr &&
 203                     parms->link == t->parms.link) {
 204                         if (create)
 205                                 return NULL;
 206                         else
 207                                 return t;
 208                 }
 209         }
 210         if (!create)
 211                 goto failed;
 212
 213         if (parms->name[0])
 214                 strlcpy(name, parms->name, IFNAMSIZ);
 215         else
 216                 sprintf(name, "sit%%d");
 217
 218         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
 219         if (dev == NULL)
 220                 return NULL;
 221
 222         dev_net_set(dev, net);
 223
 224         if (strchr(name, '%')) {
 225                 if (dev_alloc_name(dev, name) < 0)
 226                         goto failed_free;
 227         }
 228
 229         nt = netdev_priv(dev);
 230
 231         nt->parms = *parms;
 232         ipip6_tunnel_init(dev);
 233         ipip6_tunnel_clone_6rd(dev, sitn);
 234
 235         if (parms->i_flags & SIT_ISATAP)
 236                 dev->priv_flags |= IFF_ISATAP;
 237
 238         if (register_netdevice(dev) < 0)
 239                 goto failed_free;
 240
 241         dev_hold(dev);
 242
 243         ipip6_tunnel_link(sitn, nt);
 244         return nt;
 245
 246 failed_free:
 247         free_netdev(dev);
 248 failed:
 249         return NULL;
 250 }
 251
 252 #define for_each_prl_rcu(start)                 \
 253         for (prl = rcu_dereference(start);      \
 254              prl;                               \
 255              prl = rcu_dereference(prl->next))
 256
 257 static struct ip_tunnel_prl_entry *
 258 __ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
 259 {
 260         struct ip_tunnel_prl_entry *prl;
 261
 262         for_each_prl_rcu(t->prl)
 263                 if (prl->addr == addr)
 264                         break;
 265         return prl;
 266
 267 }
 268
 269 static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
 270                                 struct ip_tunnel_prl __user *a)
 271 {
 272         struct ip_tunnel_prl kprl, *kp;
 273         struct ip_tunnel_prl_entry *prl;
 274         unsigned int cmax, c = 0, ca, len;
 275         int ret = 0;
 276
 277         if (copy_from_user(&kprl, a, sizeof(kprl)))
 278                 return -EFAULT;
 279         cmax = kprl.datalen / sizeof(kprl);
 280         if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
 281                 cmax = 1;
 282
 283         /* For simple GET or for root users,
 284          * we try harder to allocate.
 285          */
 286         kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
 287                 kcalloc(cmax, sizeof(*kp), GFP_KERNEL) :
 288                 NULL;
 289
 290         rcu_read_lock();
 291
 292         ca = t->prl_count < cmax ? t->prl_count : cmax;
 293
 294         if (!kp) {
 295                 /* We don't try hard to allocate much memory for
 296                  * non-root users.
 297                  * For root users, retry allocating enough memory for
 298                  * the answer.
 299                  */
 300                 kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC);
 301                 if (!kp) {
 302                         ret = -ENOMEM;
 303                         goto out;
 304                 }
 305         }
 306
 307         c = 0;
 308         for_each_prl_rcu(t->prl) {
 309                 if (c >= cmax)
 310                         break;
 311                 if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
 312                         continue;
 313                 kp[c].addr = prl->addr;
 314                 kp[c].flags = prl->flags;
 315                 c++;
 316                 if (kprl.addr != htonl(INADDR_ANY))
 317                         break;
 318         }
 319 out:
 320         rcu_read_unlock();
 321
 322         len = sizeof(*kp) * c;
 323         ret = 0;
 324         if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
 325                 ret = -EFAULT;
 326
 327         kfree(kp);
 328
 329         return ret;
 330 }
 331
 332 static int
 333 ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
 334 {
 335         struct ip_tunnel_prl_entry *p;
 336         int err = 0;
 337
 338         if (a->addr == htonl(INADDR_ANY))
 339                 return -EINVAL;
 340
 341         ASSERT_RTNL();
 342
 343         for (p = t->prl; p; p = p->next) {
 344                 if (p->addr == a->addr) {
 345                         if (chg) {
 346                                 p->flags = a->flags;
 347                                 goto out;
 348                         }
 349                         err = -EEXIST;
 350                         goto out;
 351                 }
 352         }
 353
 354         if (chg) {
 355                 err = -ENXIO;
 356                 goto out;
 357         }
 358
 359         p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
 360         if (!p) {
 361                 err = -ENOBUFS;
 362                 goto out;
 363         }
 364
 365         p->next = t->prl;
 366         p->addr = a->addr;
 367         p->flags = a->flags;
 368         t->prl_count++;
 369         rcu_assign_pointer(t->prl, p);
 370 out:
 371         return err;
 372 }
 373
 374 static void prl_entry_destroy_rcu(struct rcu_head *head)
 375 {
 376         kfree(container_of(head, struct ip_tunnel_prl_entry, rcu_head));
 377 }
 378
 379 static void prl_list_destroy_rcu(struct rcu_head *head)
 380 {
 381         struct ip_tunnel_prl_entry *p, *n;
 382
 383         p = container_of(head, struct ip_tunnel_prl_entry, rcu_head);
 384         do {
 385                 n = p->next;
 386                 kfree(p);
 387                 p = n;
 388         } while (p);
 389 }
 390
 391 static int
 392 ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
 393 {
 394         struct ip_tunnel_prl_entry *x, **p;
 395         int err = 0;
 396
 397         ASSERT_RTNL();
 398
 399         if (a && a->addr != htonl(INADDR_ANY)) {
 400                 for (p = &t->prl; *p; p = &(*p)->next) {
 401                         if ((*p)->addr == a->addr) {
 402                                 x = *p;
 403                                 *p = x->next;
 404                                 call_rcu(&x->rcu_head, prl_entry_destroy_rcu);
 405                                 t->prl_count--;
 406                                 goto out;
 407                         }
 408                 }
 409                 err = -ENXIO;
 410         } else {
 411                 if (t->prl) {
 412                         t->prl_count = 0;
 413                         x = t->prl;
 414                         call_rcu(&x->rcu_head, prl_list_destroy_rcu);
 415                         t->prl = NULL;
 416                 }
 417         }
 418 out:
 419         return err;
 420 }
 421
 422 static int
 423 isatap_chksrc(struct sk_buff *skb, struct iphdr *iph, struct ip_tunnel *t)
 424 {
 425         struct ip_tunnel_prl_entry *p;
 426         int ok = 1;
 427
 428         rcu_read_lock();
 429         p = __ipip6_tunnel_locate_prl(t, iph->saddr);
 430         if (p) {
 431                 if (p->flags & PRL_DEFAULT)
 432                         skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
 433                 else
 434                         skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
 435         } else {
 436                 struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
 437                 if (ipv6_addr_is_isatap(addr6) &&
 438                     (addr6->s6_addr32[3] == iph->saddr) &&
 439                     ipv6_chk_prefix(addr6, t->dev))
 440                         skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
 441                 else
 442                         ok = 0;
 443         }
 444         rcu_read_unlock();
 445         return ok;
 446 }
 447
 448 static void ipip6_tunnel_uninit(struct net_device *dev)
 449 {
 450         struct net *net = dev_net(dev);
 451         struct sit_net *sitn = net_generic(net, sit_net_id);
 452
 453         if (dev == sitn->fb_tunnel_dev) {
 454                 spin_lock_bh(&ipip6_lock);
 455                 sitn->tunnels_wc[0] = NULL;
 456                 spin_unlock_bh(&ipip6_lock);
 457                 dev_put(dev);
 458         } else {
 459                 ipip6_tunnel_unlink(sitn, netdev_priv(dev));
 460                 ipip6_tunnel_del_prl(netdev_priv(dev), NULL);
 461                 dev_put(dev);
 462         }
 463 }
 464
 465
 466 static int ipip6_err(struct sk_buff *skb, u32 info)
 467 {
 468
 469 /* All the routers (except for Linux) return only
 470    8 bytes of packet payload. It means, that precise relaying of
 471    ICMP in the real Internet is absolutely infeasible.
 472  */
 473         struct iphdr *iph = (struct iphdr*)skb->data;
 474         const int type = icmp_hdr(skb)->type;
 475         const int code = icmp_hdr(skb)->code;
 476         struct ip_tunnel *t;
 477         int err;
 478
 479         switch (type) {
 480         default:
 481         case ICMP_PARAMETERPROB:
 482                 return 0;
 483
 484         case ICMP_DEST_UNREACH:
 485                 switch (code) {
 486                 case ICMP_SR_FAILED:
 487                 case ICMP_PORT_UNREACH:
 488                         /* Impossible event. */
 489                         return 0;
 490                 case ICMP_FRAG_NEEDED:
 491                         /* Soft state for pmtu is maintained by IP core. */
 492                         return 0;
 493                 default:
 494                         /* All others are translated to HOST_UNREACH.
 495                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 496                            I believe they are just ether pollution. --ANK
 497                          */
 498                         break;
 499                 }
 500                 break;
 501         case ICMP_TIME_EXCEEDED:
 502                 if (code != ICMP_EXC_TTL)
 503                         return 0;
 504                 break;
 505         }
 506
 507         err = -ENOENT;
 508
 509         rcu_read_lock();
 510         t = ipip6_tunnel_lookup(dev_net(skb->dev),
 511                                 skb->dev,
 512                                 iph->daddr,
 513                                 iph->saddr);
 514         if (t == NULL || t->parms.iph.daddr == 0)
 515                 goto out;
 516
 517         err = 0;
 518         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 519                 goto out;
 520
 521         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
 522                 t->err_count++;
 523         else
 524                 t->err_count = 1;
 525         t->err_time = jiffies;
 526 out:
 527         rcu_read_unlock();
 528         return err;
 529 }
 530
 531 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 532 {
 533         if (INET_ECN_is_ce(iph->tos))
 534                 IP6_ECN_set_ce(ipv6_hdr(skb));
 535 }
 536
 537 static int ipip6_rcv(struct sk_buff *skb)
 538 {
 539         struct iphdr *iph;
 540         struct ip_tunnel *tunnel;
 541
 542         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 543                 goto out;
 544
 545         iph = ip_hdr(skb);
 546
 547         rcu_read_lock();
 548         tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
 549                                      iph->saddr, iph->daddr);
 550         if (tunnel != NULL) {
 551                 secpath_reset(skb);
 552                 skb->mac_header = skb->network_header;
 553                 skb_reset_network_header(skb);
 554                 IPCB(skb)->flags = 0;
 555                 skb->protocol = htons(ETH_P_IPV6);
 556                 skb->pkt_type = PACKET_HOST;
 557
 558                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
 559                     !isatap_chksrc(skb, iph, tunnel)) {
 560                         tunnel->dev->stats.rx_errors++;
 561                         rcu_read_unlock();
 562                         kfree_skb(skb);
 563                         return 0;
 564                 }
 565
 566                 skb_tunnel_rx(skb, tunnel->dev);
 567
 568                 ipip6_ecn_decapsulate(iph, skb);
 569                 netif_rx(skb);
 570                 rcu_read_unlock();
 571                 return 0;
 572         }
 573
 574         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 575         rcu_read_unlock();
 576 out:
 577         kfree_skb(skb);
 578         return 0;
 579 }
 580
 581 /*
 582  * Returns the embedded IPv4 address if the IPv6 address
 583  * comes from 6rd / 6to4 (RFC 3056) addr space.
 584  */
 585 static inline
 586 __be32 try_6rd(struct in6_addr *v6dst, struct ip_tunnel *tunnel)
 587 {
 588         __be32 dst = 0;
 589
 590 #ifdef CONFIG_IPV6_SIT_6RD
 591         if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
 592                               tunnel->ip6rd.prefixlen)) {
 593                 unsigned pbw0, pbi0;
 594                 int pbi1;
 595                 u32 d;
 596
 597                 pbw0 = tunnel->ip6rd.prefixlen >> 5;
 598                 pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
 599
 600                 d = (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
 601                     tunnel->ip6rd.relay_prefixlen;
 602
 603                 pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
 604                 if (pbi1 > 0)
 605                         d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
 606                              (32 - pbi1);
 607
 608                 dst = tunnel->ip6rd.relay_prefix | htonl(d);
 609         }
 610 #else
 611         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 612                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 613                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 614         }
 615 #endif
 616         return dst;
 617 }
 618
 619 /*
 620  *      This function assumes it is being called from dev_queue_xmit()
 621  *      and that skb is filled properly by that function.
 622  */
 623
 624 static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 625                                      struct net_device *dev)
 626 {
 627         struct ip_tunnel *tunnel = netdev_priv(dev);
 628         struct net_device_stats *stats = &dev->stats;
 629         struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
 630         struct iphdr  *tiph = &tunnel->parms.iph;
 631         struct ipv6hdr *iph6 = ipv6_hdr(skb);
 632         u8     tos = tunnel->parms.iph.tos;
 633         __be16 df = tiph->frag_off;
 634         struct rtable *rt;                      /* Route to the other host */
 635         struct net_device *tdev;                        /* Device to other host */
 636         struct iphdr  *iph;                     /* Our new IP header */
 637         unsigned int max_headroom;              /* The extra header space needed */
 638         __be32 dst = tiph->daddr;
 639         int    mtu;
 640         struct in6_addr *addr6;
 641         int addr_type;
 642
 643         if (skb->protocol != htons(ETH_P_IPV6))
 644                 goto tx_error;
 645
 646         /* ISATAP (RFC4214) - must come before 6to4 */
 647         if (dev->priv_flags & IFF_ISATAP) {
 648                 struct neighbour *neigh = NULL;
 649
 650                 if (skb_dst(skb))
 651                         neigh = skb_dst(skb)->neighbour;
 652
 653                 if (neigh == NULL) {
 654                         if (net_ratelimit())
 655                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 656                         goto tx_error;
 657                 }
 658
 659                 addr6 = (struct in6_addr*)&neigh->primary_key;
 660                 addr_type = ipv6_addr_type(addr6);
 661
 662                 if ((addr_type & IPV6_ADDR_UNICAST) &&
 663                      ipv6_addr_is_isatap(addr6))
 664                         dst = addr6->s6_addr32[3];
 665                 else
 666                         goto tx_error;
 667         }
 668
 669         if (!dst)
 670                 dst = try_6rd(&iph6->daddr, tunnel);
 671
 672         if (!dst) {
 673                 struct neighbour *neigh = NULL;
 674
 675                 if (skb_dst(skb))
 676                         neigh = skb_dst(skb)->neighbour;
 677
 678                 if (neigh == NULL) {
 679                         if (net_ratelimit())
 680                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 681                         goto tx_error;
 682                 }
 683
 684                 addr6 = (struct in6_addr*)&neigh->primary_key;
 685                 addr_type = ipv6_addr_type(addr6);
 686
 687                 if (addr_type == IPV6_ADDR_ANY) {
 688                         addr6 = &ipv6_hdr(skb)->daddr;
 689                         addr_type = ipv6_addr_type(addr6);
 690                 }
 691
 692                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 693                         goto tx_error_icmp;
 694
 695                 dst = addr6->s6_addr32[3];
 696         }
 697
 698         {
 699                 struct flowi fl = { .nl_u = { .ip4_u =
 700                                               { .daddr = dst,
 701                                                 .saddr = tiph->saddr,
 702                                                 .tos = RT_TOS(tos) } },
 703                                     .oif = tunnel->parms.link,
 704                                     .proto = IPPROTO_IPV6 };
 705                 if (ip_route_output_key(dev_net(dev), &rt, &fl)) {
 706                         stats->tx_carrier_errors++;
 707                         goto tx_error_icmp;
 708                 }
 709         }
 710         if (rt->rt_type != RTN_UNICAST) {
 711                 ip_rt_put(rt);
 712                 stats->tx_carrier_errors++;
 713                 goto tx_error_icmp;
 714         }
 715         tdev = rt->dst.dev;
 716
 717         if (tdev == dev) {
 718                 ip_rt_put(rt);
 719                 stats->collisions++;
 720                 goto tx_error;
 721         }
 722
 723         if (df) {
 724                 mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
 725
 726                 if (mtu < 68) {
 727                         stats->collisions++;
 728                         ip_rt_put(rt);
 729                         goto tx_error;
 730                 }
 731
 732                 if (mtu < IPV6_MIN_MTU) {
 733                         mtu = IPV6_MIN_MTU;
 734                         df = 0;
 735                 }
 736
 737                 if (tunnel->parms.iph.daddr && skb_dst(skb))
 738                         skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 739
 740                 if (skb->len > mtu) {
 741                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
 742                         ip_rt_put(rt);
 743                         goto tx_error;
 744                 }
 745         }
 746
 747         if (tunnel->err_count > 0) {
 748                 if (time_before(jiffies,
 749                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
 750                         tunnel->err_count--;
 751                         dst_link_failure(skb);
 752                 } else
 753                         tunnel->err_count = 0;
 754         }
 755
 756         /*
 757          * Okay, now see if we can stuff it in the buffer as-is.
 758          */
 759         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 760
 761         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 762             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 763                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 764                 if (!new_skb) {
 765                         ip_rt_put(rt);
 766                         txq->tx_dropped++;
 767                         dev_kfree_skb(skb);
 768                         return NETDEV_TX_OK;
 769                 }
 770                 if (skb->sk)
 771                         skb_set_owner_w(new_skb, skb->sk);
 772                 dev_kfree_skb(skb);
 773                 skb = new_skb;
 774                 iph6 = ipv6_hdr(skb);
 775         }
 776
 777         skb->transport_header = skb->network_header;
 778         skb_push(skb, sizeof(struct iphdr));
 779         skb_reset_network_header(skb);
 780         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 781         IPCB(skb)->flags = 0;
 782         skb_dst_drop(skb);
 783         skb_dst_set(skb, &rt->dst);
 784
 785         /*
 786          *      Push down and install the IPIP header.
 787          */
 788
 789         iph                     =       ip_hdr(skb);
 790         iph->version            =       4;
 791         iph->ihl                =       sizeof(struct iphdr)>>2;
 792         iph->frag_off           =       df;
 793         iph->protocol           =       IPPROTO_IPV6;
 794         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 795         iph->daddr              =       rt->rt_dst;
 796         iph->saddr              =       rt->rt_src;
 797
 798         if ((iph->ttl = tiph->ttl) == 0)
 799                 iph->ttl        =       iph6->hop_limit;
 800
 801         nf_reset(skb);
 802
 803         IPTUNNEL_XMIT();
 804         return NETDEV_TX_OK;
 805
 806 tx_error_icmp:
 807         dst_link_failure(skb);
 808 tx_error:
 809         stats->tx_errors++;
 810         dev_kfree_skb(skb);
 811         return NETDEV_TX_OK;
 812 }
 813
 814 static void ipip6_tunnel_bind_dev(struct net_device *dev)
 815 {
 816         struct net_device *tdev = NULL;
 817         struct ip_tunnel *tunnel;
 818         struct iphdr *iph;
 819
 820         tunnel = netdev_priv(dev);
 821         iph = &tunnel->parms.iph;
 822
 823         if (iph->daddr) {
 824                 struct flowi fl = { .nl_u = { .ip4_u =
 825                                               { .daddr = iph->daddr,
 826                                                 .saddr = iph->saddr,
 827                                                 .tos = RT_TOS(iph->tos) } },
 828                                     .oif = tunnel->parms.link,
 829                                     .proto = IPPROTO_IPV6 };
 830                 struct rtable *rt;
 831                 if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 832                         tdev = rt->dst.dev;
 833                         ip_rt_put(rt);
 834                 }
 835                 dev->flags |= IFF_POINTOPOINT;
 836         }
 837
 838         if (!tdev && tunnel->parms.link)
 839                 tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);
 840
 841         if (tdev) {
 842                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 843                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 844                 if (dev->mtu < IPV6_MIN_MTU)
 845                         dev->mtu = IPV6_MIN_MTU;
 846         }
 847         dev->iflink = tunnel->parms.link;
 848 }
 849
 850 static int
 851 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 852 {
 853         int err = 0;
 854         struct ip_tunnel_parm p;
 855         struct ip_tunnel_prl prl;
 856         struct ip_tunnel *t;
 857         struct net *net = dev_net(dev);
 858         struct sit_net *sitn = net_generic(net, sit_net_id);
 859 #ifdef CONFIG_IPV6_SIT_6RD
 860         struct ip_tunnel_6rd ip6rd;
 861 #endif
 862
 863         switch (cmd) {
 864         case SIOCGETTUNNEL:
 865 #ifdef CONFIG_IPV6_SIT_6RD
 866         case SIOCGET6RD:
 867 #endif
 868                 t = NULL;
 869                 if (dev == sitn->fb_tunnel_dev) {
 870                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 871                                 err = -EFAULT;
 872                                 break;
 873                         }
 874                         t = ipip6_tunnel_locate(net, &p, 0);
 875                 }
 876                 if (t == NULL)
 877                         t = netdev_priv(dev);
 878
 879                 err = -EFAULT;
 880                 if (cmd == SIOCGETTUNNEL) {
 881                         memcpy(&p, &t->parms, sizeof(p));
 882                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p,
 883                                          sizeof(p)))
 884                                 goto done;
 885 #ifdef CONFIG_IPV6_SIT_6RD
 886                 } else {
 887                         ipv6_addr_copy(&ip6rd.prefix, &t->ip6rd.prefix);
 888                         ip6rd.relay_prefix = t->ip6rd.relay_prefix;
 889                         ip6rd.prefixlen = t->ip6rd.prefixlen;
 890                         ip6rd.relay_prefixlen = t->ip6rd.relay_prefixlen;
 891                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &ip6rd,
 892                                          sizeof(ip6rd)))
 893                                 goto done;
 894 #endif
 895                 }
 896                 err = 0;
 897                 break;
 898
 899         case SIOCADDTUNNEL:
 900         case SIOCCHGTUNNEL:
 901                 err = -EPERM;
 902                 if (!capable(CAP_NET_ADMIN))
 903                         goto done;
 904
 905                 err = -EFAULT;
 906                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 907                         goto done;
 908
 909                 err = -EINVAL;
 910                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 911                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 912                         goto done;
 913                 if (p.iph.ttl)
 914                         p.iph.frag_off |= htons(IP_DF);
 915
 916                 t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
 917
 918                 if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 919                         if (t != NULL) {
 920                                 if (t->dev != dev) {
 921                                         err = -EEXIST;
 922                                         break;
 923                                 }
 924                         } else {
 925                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 926                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 927                                         err = -EINVAL;
 928                                         break;
 929                                 }
 930                                 t = netdev_priv(dev);
 931                                 ipip6_tunnel_unlink(sitn, t);
 932                                 t->parms.iph.saddr = p.iph.saddr;
 933                                 t->parms.iph.daddr = p.iph.daddr;
 934                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 935                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 936                                 ipip6_tunnel_link(sitn, t);
 937                                 netdev_state_change(dev);
 938                         }
 939                 }
 940
 941                 if (t) {
 942                         err = 0;
 943                         if (cmd == SIOCCHGTUNNEL) {
 944                                 t->parms.iph.ttl = p.iph.ttl;
 945                                 t->parms.iph.tos = p.iph.tos;
 946                                 if (t->parms.link != p.link) {
 947                                         t->parms.link = p.link;
 948                                         ipip6_tunnel_bind_dev(dev);
 949                                         netdev_state_change(dev);
 950                                 }
 951                         }
 952                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 953                                 err = -EFAULT;
 954                 } else
 955                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 956                 break;
 957
 958         case SIOCDELTUNNEL:
 959                 err = -EPERM;
 960                 if (!capable(CAP_NET_ADMIN))
 961                         goto done;
 962
 963                 if (dev == sitn->fb_tunnel_dev) {
 964                         err = -EFAULT;
 965                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 966                                 goto done;
 967                         err = -ENOENT;
 968                         if ((t = ipip6_tunnel_locate(net, &p, 0)) == NULL)
 969                                 goto done;
 970                         err = -EPERM;
 971                         if (t == netdev_priv(sitn->fb_tunnel_dev))
 972                                 goto done;
 973                         dev = t->dev;
 974                 }
 975                 unregister_netdevice(dev);
 976                 err = 0;
 977                 break;
 978
 979         case SIOCGETPRL:
 980                 err = -EINVAL;
 981                 if (dev == sitn->fb_tunnel_dev)
 982                         goto done;
 983                 err = -ENOENT;
 984                 if (!(t = netdev_priv(dev)))
 985                         goto done;
 986                 err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
 987                 break;
 988
 989         case SIOCADDPRL:
 990         case SIOCDELPRL:
 991         case SIOCCHGPRL:
 992                 err = -EPERM;
 993                 if (!capable(CAP_NET_ADMIN))
 994                         goto done;
 995                 err = -EINVAL;
 996                 if (dev == sitn->fb_tunnel_dev)
 997                         goto done;
 998                 err = -EFAULT;
 999                 if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
1000                         goto done;
1001                 err = -ENOENT;
1002                 if (!(t = netdev_priv(dev)))
1003                         goto done;
1004
1005                 switch (cmd) {
1006                 case SIOCDELPRL:
1007                         err = ipip6_tunnel_del_prl(t, &prl);
1008                         break;
1009                 case SIOCADDPRL:
1010                 case SIOCCHGPRL:
1011                         err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
1012                         break;
1013                 }
1014                 netdev_state_change(dev);
1015                 break;
1016
1017 #ifdef CONFIG_IPV6_SIT_6RD
1018         case SIOCADD6RD:
1019         case SIOCCHG6RD:
1020         case SIOCDEL6RD:
1021                 err = -EPERM;
1022                 if (!capable(CAP_NET_ADMIN))
1023                         goto done;
1024
1025                 err = -EFAULT;
1026                 if (copy_from_user(&ip6rd, ifr->ifr_ifru.ifru_data,
1027                                    sizeof(ip6rd)))
1028                         goto done;
1029
1030                 t = netdev_priv(dev);
1031
1032                 if (cmd != SIOCDEL6RD) {
1033                         struct in6_addr prefix;
1034                         __be32 relay_prefix;
1035
1036                         err = -EINVAL;
1037                         if (ip6rd.relay_prefixlen > 32 ||
1038                             ip6rd.prefixlen + (32 - ip6rd.relay_prefixlen) > 64)
1039                                 goto done;
1040
1041                         ipv6_addr_prefix(&prefix, &ip6rd.prefix,
1042                                          ip6rd.prefixlen);
1043                         if (!ipv6_addr_equal(&prefix, &ip6rd.prefix))
1044                                 goto done;
1045                         if (ip6rd.relay_prefixlen)
1046                                 relay_prefix = ip6rd.relay_prefix &
1047                                                htonl(0xffffffffUL <<
1048                                                      (32 - ip6rd.relay_prefixlen));
1049                         else
1050                                 relay_prefix = 0;
1051                         if (relay_prefix != ip6rd.relay_prefix)
1052                                 goto done;
1053
1054                         ipv6_addr_copy(&t->ip6rd.prefix, &prefix);
1055                         t->ip6rd.relay_prefix = relay_prefix;
1056                         t->ip6rd.prefixlen = ip6rd.prefixlen;
1057                         t->ip6rd.relay_prefixlen = ip6rd.relay_prefixlen;
1058                 } else
1059                         ipip6_tunnel_clone_6rd(dev, sitn);
1060
1061                 err = 0;
1062                 break;
1063 #endif
1064
1065         default:
1066                 err = -EINVAL;
1067         }
1068
1069 done:
1070         return err;
1071 }
1072
1073 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1074 {
1075         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
1076                 return -EINVAL;
1077         dev->mtu = new_mtu;
1078         return 0;
1079 }
1080
1081 static const struct net_device_ops ipip6_netdev_ops = {
1082         .ndo_uninit     = ipip6_tunnel_uninit,
1083         .ndo_start_xmit = ipip6_tunnel_xmit,
1084         .ndo_do_ioctl   = ipip6_tunnel_ioctl,
1085         .ndo_change_mtu = ipip6_tunnel_change_mtu,
1086 };
1087
1088 static void ipip6_tunnel_setup(struct net_device *dev)
1089 {
1090         dev->netdev_ops         = &ipip6_netdev_ops;
1091         dev->destructor         = free_netdev;
1092
1093         dev->type               = ARPHRD_SIT;
1094         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
1095         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
1096         dev->flags              = IFF_NOARP;
1097         dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
1098         dev->iflink             = 0;
1099         dev->addr_len           = 4;
1100         dev->features           |= NETIF_F_NETNS_LOCAL;
1101 }
1102
1103 static void ipip6_tunnel_init(struct net_device *dev)
1104 {
1105         struct ip_tunnel *tunnel = netdev_priv(dev);
1106
1107         tunnel->dev = dev;
1108         strcpy(tunnel->parms.name, dev->name);
1109
1110         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1111         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1112
1113         ipip6_tunnel_bind_dev(dev);
1114 }
1115
1116 static void __net_init ipip6_fb_tunnel_init(struct net_device *dev)
1117 {
1118         struct ip_tunnel *tunnel = netdev_priv(dev);
1119         struct iphdr *iph = &tunnel->parms.iph;
1120         struct net *net = dev_net(dev);
1121         struct sit_net *sitn = net_generic(net, sit_net_id);
1122
1123         tunnel->dev = dev;
1124         strcpy(tunnel->parms.name, dev->name);
1125
1126         iph->version            = 4;
1127         iph->protocol           = IPPROTO_IPV6;
1128         iph->ihl                = 5;
1129         iph->ttl                = 64;
1130
1131         dev_hold(dev);
1132         sitn->tunnels_wc[0]     = tunnel;
1133 }
1134
1135 static struct xfrm_tunnel sit_handler = {
1136         .handler        =       ipip6_rcv,
1137         .err_handler    =       ipip6_err,
1138         .priority       =       1,
1139 };
1140
1141 static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_head *head)
1142 {
1143         int prio;
1144
1145         for (prio = 1; prio < 4; prio++) {
1146                 int h;
1147                 for (h = 0; h < HASH_SIZE; h++) {
1148                         struct ip_tunnel *t = sitn->tunnels[prio][h];
1149
1150                         while (t != NULL) {
1151                                 unregister_netdevice_queue(t->dev, head);
1152                                 t = t->next;
1153                         }
1154                 }
1155         }
1156 }
1157
1158 static int __net_init sit_init_net(struct net *net)
1159 {
1160         struct sit_net *sitn = net_generic(net, sit_net_id);
1161         int err;
1162
1163         sitn->tunnels[0] = sitn->tunnels_wc;
1164         sitn->tunnels[1] = sitn->tunnels_l;
1165         sitn->tunnels[2] = sitn->tunnels_r;
1166         sitn->tunnels[3] = sitn->tunnels_r_l;
1167
1168         sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
1169                                            ipip6_tunnel_setup);
1170         if (!sitn->fb_tunnel_dev) {
1171                 err = -ENOMEM;
1172                 goto err_alloc_dev;
1173         }
1174         dev_net_set(sitn->fb_tunnel_dev, net);
1175
1176         ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
1177         ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
1178
1179         if ((err = register_netdev(sitn->fb_tunnel_dev)))
1180                 goto err_reg_dev;
1181
1182         return 0;
1183
1184 err_reg_dev:
1185         dev_put(sitn->fb_tunnel_dev);
1186         free_netdev(sitn->fb_tunnel_dev);
1187 err_alloc_dev:
1188         return err;
1189 }
1190
1191 static void __net_exit sit_exit_net(struct net *net)
1192 {
1193         struct sit_net *sitn = net_generic(net, sit_net_id);
1194         LIST_HEAD(list);
1195
1196         rtnl_lock();
1197         sit_destroy_tunnels(sitn, &list);
1198         unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);
1199         unregister_netdevice_many(&list);
1200         rtnl_unlock();
1201 }
1202
1203 static struct pernet_operations sit_net_ops = {
1204         .init = sit_init_net,
1205         .exit = sit_exit_net,
1206         .id   = &sit_net_id,
1207         .size = sizeof(struct sit_net),
1208 };
1209
1210 static void __exit sit_cleanup(void)
1211 {
1212         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1213
1214         unregister_pernet_device(&sit_net_ops);
1215         rcu_barrier(); /* Wait for completion of call_rcu()'s */
1216 }
1217
1218 static int __init sit_init(void)
1219 {
1220         int err;
1221
1222         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
1223
1224         err = register_pernet_device(&sit_net_ops);
1225         if (err < 0)
1226                 return err;
1227         err = xfrm4_tunnel_register(&sit_handler, AF_INET6);
1228         if (err < 0) {
1229                 unregister_pernet_device(&sit_net_ops);
1230                 printk(KERN_INFO "sit init: Can't add protocol\n");
1231         }
1232         return err;
1233 }
1234
1235 module_init(sit_init);
1236 module_exit(sit_cleanup);
1237 MODULE_LICENSE("GPL");
1238 MODULE_ALIAS("sit0");