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   1 /*
   2  *      IPv6 over IPv4 tunnel device - Simple Internet Transition (SIT)
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
   8  *
   9  *      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_tunnel_init(struct net_device *dev);
  66 static void ipip6_tunnel_setup(struct net_device *dev);
  67
  68 static int sit_net_id __read_mostly;
  69 struct sit_net {
  70         struct ip_tunnel *tunnels_r_l[HASH_SIZE];
  71         struct ip_tunnel *tunnels_r[HASH_SIZE];
  72         struct ip_tunnel *tunnels_l[HASH_SIZE];
  73         struct ip_tunnel *tunnels_wc[1];
  74         struct ip_tunnel **tunnels[4];
  75
  76         struct net_device *fb_tunnel_dev;
  77 };
  78
  79 /*
  80  * Locking : hash tables are protected by RCU and a spinlock
  81  */
  82 static DEFINE_SPINLOCK(ipip6_lock);
  83
  84 #define for_each_ip_tunnel_rcu(start) \
  85         for (t = rcu_dereference(start); t; t = rcu_dereference(t->next))
  86
  87 /*
  88  * Must be invoked with rcu_read_lock
  89  */
  90 static struct ip_tunnel * ipip6_tunnel_lookup(struct net *net,
  91                 struct net_device *dev, __be32 remote, __be32 local)
  92 {
  93         unsigned h0 = HASH(remote);
  94         unsigned h1 = HASH(local);
  95         struct ip_tunnel *t;
  96         struct sit_net *sitn = net_generic(net, sit_net_id);
  97
  98         for_each_ip_tunnel_rcu(sitn->tunnels_r_l[h0 ^ h1]) {
  99                 if (local == t->parms.iph.saddr &&
 100                     remote == t->parms.iph.daddr &&
 101                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 102                     (t->dev->flags & IFF_UP))
 103                         return t;
 104         }
 105         for_each_ip_tunnel_rcu(sitn->tunnels_r[h0]) {
 106                 if (remote == t->parms.iph.daddr &&
 107                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 108                     (t->dev->flags & IFF_UP))
 109                         return t;
 110         }
 111         for_each_ip_tunnel_rcu(sitn->tunnels_l[h1]) {
 112                 if (local == t->parms.iph.saddr &&
 113                     (!dev || !t->parms.link || dev->iflink == t->parms.link) &&
 114                     (t->dev->flags & IFF_UP))
 115                         return t;
 116         }
 117         t = rcu_dereference(sitn->tunnels_wc[0]);
 118         if ((t != NULL) && (t->dev->flags & IFF_UP))
 119                 return t;
 120         return NULL;
 121 }
 122
 123 static struct ip_tunnel **__ipip6_bucket(struct sit_net *sitn,
 124                 struct ip_tunnel_parm *parms)
 125 {
 126         __be32 remote = parms->iph.daddr;
 127         __be32 local = parms->iph.saddr;
 128         unsigned h = 0;
 129         int prio = 0;
 130
 131         if (remote) {
 132                 prio |= 2;
 133                 h ^= HASH(remote);
 134         }
 135         if (local) {
 136                 prio |= 1;
 137                 h ^= HASH(local);
 138         }
 139         return &sitn->tunnels[prio][h];
 140 }
 141
 142 static inline struct ip_tunnel **ipip6_bucket(struct sit_net *sitn,
 143                 struct ip_tunnel *t)
 144 {
 145         return __ipip6_bucket(sitn, &t->parms);
 146 }
 147
 148 static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
 149 {
 150         struct ip_tunnel **tp;
 151
 152         for (tp = ipip6_bucket(sitn, t); *tp; tp = &(*tp)->next) {
 153                 if (t == *tp) {
 154                         spin_lock_bh(&ipip6_lock);
 155                         *tp = t->next;
 156                         spin_unlock_bh(&ipip6_lock);
 157                         break;
 158                 }
 159         }
 160 }
 161
 162 static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
 163 {
 164         struct ip_tunnel **tp = ipip6_bucket(sitn, t);
 165
 166         spin_lock_bh(&ipip6_lock);
 167         t->next = *tp;
 168         rcu_assign_pointer(*tp, t);
 169         spin_unlock_bh(&ipip6_lock);
 170 }
 171
 172 static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
 173 {
 174 #ifdef CONFIG_IPV6_SIT_6RD
 175         struct ip_tunnel *t = netdev_priv(dev);
 176
 177         if (t->dev == sitn->fb_tunnel_dev) {
 178                 ipv6_addr_set(&t->ip6rd.prefix, htonl(0x20020000), 0, 0, 0);
 179                 t->ip6rd.relay_prefix = 0;
 180                 t->ip6rd.prefixlen = 16;
 181                 t->ip6rd.relay_prefixlen = 0;
 182         } else {
 183                 struct ip_tunnel *t0 = netdev_priv(sitn->fb_tunnel_dev);
 184                 memcpy(&t->ip6rd, &t0->ip6rd, sizeof(t->ip6rd));
 185         }
 186 #endif
 187 }
 188
 189 static struct ip_tunnel * ipip6_tunnel_locate(struct net *net,
 190                 struct ip_tunnel_parm *parms, int create)
 191 {
 192         __be32 remote = parms->iph.daddr;
 193         __be32 local = parms->iph.saddr;
 194         struct ip_tunnel *t, **tp, *nt;
 195         struct net_device *dev;
 196         char name[IFNAMSIZ];
 197         struct sit_net *sitn = net_generic(net, sit_net_id);
 198
 199         for (tp = __ipip6_bucket(sitn, parms); (t = *tp) != NULL; tp = &t->next) {
 200                 if (local == t->parms.iph.saddr &&
 201                     remote == t->parms.iph.daddr &&
 202                     parms->link == t->parms.link) {
 203                         if (create)
 204                                 return NULL;
 205                         else
 206                                 return t;
 207                 }
 208         }
 209         if (!create)
 210                 goto failed;
 211
 212         if (parms->name[0])
 213                 strlcpy(name, parms->name, IFNAMSIZ);
 214         else
 215                 sprintf(name, "sit%%d");
 216
 217         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
 218         if (dev == NULL)
 219                 return NULL;
 220
 221         dev_net_set(dev, net);
 222
 223         if (strchr(name, '%')) {
 224                 if (dev_alloc_name(dev, name) < 0)
 225                         goto failed_free;
 226         }
 227
 228         nt = netdev_priv(dev);
 229
 230         nt->parms = *parms;
 231         ipip6_tunnel_init(dev);
 232         ipip6_tunnel_clone_6rd(dev, sitn);
 233
 234         if (parms->i_flags & SIT_ISATAP)
 235                 dev->priv_flags |= IFF_ISATAP;
 236
 237         if (register_netdevice(dev) < 0)
 238                 goto failed_free;
 239
 240         dev_hold(dev);
 241
 242         ipip6_tunnel_link(sitn, nt);
 243         return nt;
 244
 245 failed_free:
 246         free_netdev(dev);
 247 failed:
 248         return NULL;
 249 }
 250
 251 static DEFINE_SPINLOCK(ipip6_prl_lock);
 252
 253 #define for_each_prl_rcu(start)                 \
 254         for (prl = rcu_dereference(start);      \
 255              prl;                               \
 256              prl = rcu_dereference(prl->next))
 257
 258 static struct ip_tunnel_prl_entry *
 259 __ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
 260 {
 261         struct ip_tunnel_prl_entry *prl;
 262
 263         for_each_prl_rcu(t->prl)
 264                 if (prl->addr == addr)
 265                         break;
 266         return prl;
 267
 268 }
 269
 270 static int ipip6_tunnel_get_prl(struct ip_tunnel *t,
 271                                 struct ip_tunnel_prl __user *a)
 272 {
 273         struct ip_tunnel_prl kprl, *kp;
 274         struct ip_tunnel_prl_entry *prl;
 275         unsigned int cmax, c = 0, ca, len;
 276         int ret = 0;
 277
 278         if (copy_from_user(&kprl, a, sizeof(kprl)))
 279                 return -EFAULT;
 280         cmax = kprl.datalen / sizeof(kprl);
 281         if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
 282                 cmax = 1;
 283
 284         /* For simple GET or for root users,
 285          * we try harder to allocate.
 286          */
 287         kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
 288                 kcalloc(cmax, sizeof(*kp), GFP_KERNEL) :
 289                 NULL;
 290
 291         rcu_read_lock();
 292
 293         ca = t->prl_count < cmax ? t->prl_count : cmax;
 294
 295         if (!kp) {
 296                 /* We don't try hard to allocate much memory for
 297                  * non-root users.
 298                  * For root users, retry allocating enough memory for
 299                  * the answer.
 300                  */
 301                 kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC);
 302                 if (!kp) {
 303                         ret = -ENOMEM;
 304                         goto out;
 305                 }
 306         }
 307
 308         c = 0;
 309         for_each_prl_rcu(t->prl) {
 310                 if (c >= cmax)
 311                         break;
 312                 if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
 313                         continue;
 314                 kp[c].addr = prl->addr;
 315                 kp[c].flags = prl->flags;
 316                 c++;
 317                 if (kprl.addr != htonl(INADDR_ANY))
 318                         break;
 319         }
 320 out:
 321         rcu_read_unlock();
 322
 323         len = sizeof(*kp) * c;
 324         ret = 0;
 325         if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
 326                 ret = -EFAULT;
 327
 328         kfree(kp);
 329
 330         return ret;
 331 }
 332
 333 static int
 334 ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
 335 {
 336         struct ip_tunnel_prl_entry *p;
 337         int err = 0;
 338
 339         if (a->addr == htonl(INADDR_ANY))
 340                 return -EINVAL;
 341
 342         spin_lock(&ipip6_prl_lock);
 343
 344         for (p = t->prl; p; p = p->next) {
 345                 if (p->addr == a->addr) {
 346                         if (chg) {
 347                                 p->flags = a->flags;
 348                                 goto out;
 349                         }
 350                         err = -EEXIST;
 351                         goto out;
 352                 }
 353         }
 354
 355         if (chg) {
 356                 err = -ENXIO;
 357                 goto out;
 358         }
 359
 360         p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
 361         if (!p) {
 362                 err = -ENOBUFS;
 363                 goto out;
 364         }
 365
 366         p->next = t->prl;
 367         p->addr = a->addr;
 368         p->flags = a->flags;
 369         t->prl_count++;
 370         rcu_assign_pointer(t->prl, p);
 371 out:
 372         spin_unlock(&ipip6_prl_lock);
 373         return err;
 374 }
 375
 376 static void prl_entry_destroy_rcu(struct rcu_head *head)
 377 {
 378         kfree(container_of(head, struct ip_tunnel_prl_entry, rcu_head));
 379 }
 380
 381 static void prl_list_destroy_rcu(struct rcu_head *head)
 382 {
 383         struct ip_tunnel_prl_entry *p, *n;
 384
 385         p = container_of(head, struct ip_tunnel_prl_entry, rcu_head);
 386         do {
 387                 n = p->next;
 388                 kfree(p);
 389                 p = n;
 390         } while (p);
 391 }
 392
 393 static int
 394 ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
 395 {
 396         struct ip_tunnel_prl_entry *x, **p;
 397         int err = 0;
 398
 399         spin_lock(&ipip6_prl_lock);
 400
 401         if (a && a->addr != htonl(INADDR_ANY)) {
 402                 for (p = &t->prl; *p; p = &(*p)->next) {
 403                         if ((*p)->addr == a->addr) {
 404                                 x = *p;
 405                                 *p = x->next;
 406                                 call_rcu(&x->rcu_head, prl_entry_destroy_rcu);
 407                                 t->prl_count--;
 408                                 goto out;
 409                         }
 410                 }
 411                 err = -ENXIO;
 412         } else {
 413                 if (t->prl) {
 414                         t->prl_count = 0;
 415                         x = t->prl;
 416                         call_rcu(&x->rcu_head, prl_list_destroy_rcu);
 417                         t->prl = NULL;
 418                 }
 419         }
 420 out:
 421         spin_unlock(&ipip6_prl_lock);
 422         return err;
 423 }
 424
 425 static int
 426 isatap_chksrc(struct sk_buff *skb, struct iphdr *iph, struct ip_tunnel *t)
 427 {
 428         struct ip_tunnel_prl_entry *p;
 429         int ok = 1;
 430
 431         rcu_read_lock();
 432         p = __ipip6_tunnel_locate_prl(t, iph->saddr);
 433         if (p) {
 434                 if (p->flags & PRL_DEFAULT)
 435                         skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
 436                 else
 437                         skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
 438         } else {
 439                 struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
 440                 if (ipv6_addr_is_isatap(addr6) &&
 441                     (addr6->s6_addr32[3] == iph->saddr) &&
 442                     ipv6_chk_prefix(addr6, t->dev))
 443                         skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
 444                 else
 445                         ok = 0;
 446         }
 447         rcu_read_unlock();
 448         return ok;
 449 }
 450
 451 static void ipip6_tunnel_uninit(struct net_device *dev)
 452 {
 453         struct net *net = dev_net(dev);
 454         struct sit_net *sitn = net_generic(net, sit_net_id);
 455
 456         if (dev == sitn->fb_tunnel_dev) {
 457                 spin_lock_bh(&ipip6_lock);
 458                 sitn->tunnels_wc[0] = NULL;
 459                 spin_unlock_bh(&ipip6_lock);
 460                 dev_put(dev);
 461         } else {
 462                 ipip6_tunnel_unlink(sitn, netdev_priv(dev));
 463                 ipip6_tunnel_del_prl(netdev_priv(dev), NULL);
 464                 dev_put(dev);
 465         }
 466 }
 467
 468
 469 static int ipip6_err(struct sk_buff *skb, u32 info)
 470 {
 471
 472 /* All the routers (except for Linux) return only
 473    8 bytes of packet payload. It means, that precise relaying of
 474    ICMP in the real Internet is absolutely infeasible.
 475  */
 476         struct iphdr *iph = (struct iphdr*)skb->data;
 477         const int type = icmp_hdr(skb)->type;
 478         const int code = icmp_hdr(skb)->code;
 479         struct ip_tunnel *t;
 480         int err;
 481
 482         switch (type) {
 483         default:
 484         case ICMP_PARAMETERPROB:
 485                 return 0;
 486
 487         case ICMP_DEST_UNREACH:
 488                 switch (code) {
 489                 case ICMP_SR_FAILED:
 490                 case ICMP_PORT_UNREACH:
 491                         /* Impossible event. */
 492                         return 0;
 493                 case ICMP_FRAG_NEEDED:
 494                         /* Soft state for pmtu is maintained by IP core. */
 495                         return 0;
 496                 default:
 497                         /* All others are translated to HOST_UNREACH.
 498                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 499                            I believe they are just ether pollution. --ANK
 500                          */
 501                         break;
 502                 }
 503                 break;
 504         case ICMP_TIME_EXCEEDED:
 505                 if (code != ICMP_EXC_TTL)
 506                         return 0;
 507                 break;
 508         }
 509
 510         err = -ENOENT;
 511
 512         rcu_read_lock();
 513         t = ipip6_tunnel_lookup(dev_net(skb->dev),
 514                                 skb->dev,
 515                                 iph->daddr,
 516                                 iph->saddr);
 517         if (t == NULL || t->parms.iph.daddr == 0)
 518                 goto out;
 519
 520         err = 0;
 521         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 522                 goto out;
 523
 524         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
 525                 t->err_count++;
 526         else
 527                 t->err_count = 1;
 528         t->err_time = jiffies;
 529 out:
 530         rcu_read_unlock();
 531         return err;
 532 }
 533
 534 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 535 {
 536         if (INET_ECN_is_ce(iph->tos))
 537                 IP6_ECN_set_ce(ipv6_hdr(skb));
 538 }
 539
 540 static int ipip6_rcv(struct sk_buff *skb)
 541 {
 542         struct iphdr *iph;
 543         struct ip_tunnel *tunnel;
 544
 545         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 546                 goto out;
 547
 548         iph = ip_hdr(skb);
 549
 550         rcu_read_lock();
 551         tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
 552                                      iph->saddr, iph->daddr);
 553         if (tunnel != NULL) {
 554                 secpath_reset(skb);
 555                 skb->mac_header = skb->network_header;
 556                 skb_reset_network_header(skb);
 557                 IPCB(skb)->flags = 0;
 558                 skb->protocol = htons(ETH_P_IPV6);
 559                 skb->pkt_type = PACKET_HOST;
 560
 561                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
 562                     !isatap_chksrc(skb, iph, tunnel)) {
 563                         tunnel->dev->stats.rx_errors++;
 564                         rcu_read_unlock();
 565                         kfree_skb(skb);
 566                         return 0;
 567                 }
 568                 tunnel->dev->stats.rx_packets++;
 569                 tunnel->dev->stats.rx_bytes += skb->len;
 570                 skb->dev = tunnel->dev;
 571                 skb_dst_drop(skb);
 572                 nf_reset(skb);
 573                 ipip6_ecn_decapsulate(iph, skb);
 574                 netif_rx(skb);
 575                 rcu_read_unlock();
 576                 return 0;
 577         }
 578
 579         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 580         rcu_read_unlock();
 581 out:
 582         kfree_skb(skb);
 583         return 0;
 584 }
 585
 586 /*
 587  * Returns the embedded IPv4 address if the IPv6 address
 588  * comes from 6rd / 6to4 (RFC 3056) addr space.
 589  */
 590 static inline
 591 __be32 try_6rd(struct in6_addr *v6dst, struct ip_tunnel *tunnel)
 592 {
 593         __be32 dst = 0;
 594
 595 #ifdef CONFIG_IPV6_SIT_6RD
 596         if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
 597                               tunnel->ip6rd.prefixlen)) {
 598                 unsigned pbw0, pbi0;
 599                 int pbi1;
 600                 u32 d;
 601
 602                 pbw0 = tunnel->ip6rd.prefixlen >> 5;
 603                 pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
 604
 605                 d = (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
 606                     tunnel->ip6rd.relay_prefixlen;
 607
 608                 pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
 609                 if (pbi1 > 0)
 610                         d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
 611                              (32 - pbi1);
 612
 613                 dst = tunnel->ip6rd.relay_prefix | htonl(d);
 614         }
 615 #else
 616         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 617                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 618                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 619         }
 620 #endif
 621         return dst;
 622 }
 623
 624 /*
 625  *      This function assumes it is being called from dev_queue_xmit()
 626  *      and that skb is filled properly by that function.
 627  */
 628
 629 static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 630                                      struct net_device *dev)
 631 {
 632         struct ip_tunnel *tunnel = netdev_priv(dev);
 633         struct net_device_stats *stats = &dev->stats;
 634         struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
 635         struct iphdr  *tiph = &tunnel->parms.iph;
 636         struct ipv6hdr *iph6 = ipv6_hdr(skb);
 637         u8     tos = tunnel->parms.iph.tos;
 638         __be16 df = tiph->frag_off;
 639         struct rtable *rt;                      /* Route to the other host */
 640         struct net_device *tdev;                        /* Device to other host */
 641         struct iphdr  *iph;                     /* Our new IP header */
 642         unsigned int max_headroom;              /* The extra header space needed */
 643         __be32 dst = tiph->daddr;
 644         int    mtu;
 645         struct in6_addr *addr6;
 646         int addr_type;
 647
 648         if (skb->protocol != htons(ETH_P_IPV6))
 649                 goto tx_error;
 650
 651         /* ISATAP (RFC4214) - must come before 6to4 */
 652         if (dev->priv_flags & IFF_ISATAP) {
 653                 struct neighbour *neigh = NULL;
 654
 655                 if (skb_dst(skb))
 656                         neigh = skb_dst(skb)->neighbour;
 657
 658                 if (neigh == NULL) {
 659                         if (net_ratelimit())
 660                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 661                         goto tx_error;
 662                 }
 663
 664                 addr6 = (struct in6_addr*)&neigh->primary_key;
 665                 addr_type = ipv6_addr_type(addr6);
 666
 667                 if ((addr_type & IPV6_ADDR_UNICAST) &&
 668                      ipv6_addr_is_isatap(addr6))
 669                         dst = addr6->s6_addr32[3];
 670                 else
 671                         goto tx_error;
 672         }
 673
 674         if (!dst)
 675                 dst = try_6rd(&iph6->daddr, tunnel);
 676
 677         if (!dst) {
 678                 struct neighbour *neigh = NULL;
 679
 680                 if (skb_dst(skb))
 681                         neigh = skb_dst(skb)->neighbour;
 682
 683                 if (neigh == NULL) {
 684                         if (net_ratelimit())
 685                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 686                         goto tx_error;
 687                 }
 688
 689                 addr6 = (struct in6_addr*)&neigh->primary_key;
 690                 addr_type = ipv6_addr_type(addr6);
 691
 692                 if (addr_type == IPV6_ADDR_ANY) {
 693                         addr6 = &ipv6_hdr(skb)->daddr;
 694                         addr_type = ipv6_addr_type(addr6);
 695                 }
 696
 697                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 698                         goto tx_error_icmp;
 699
 700                 dst = addr6->s6_addr32[3];
 701         }
 702
 703         {
 704                 struct flowi fl = { .nl_u = { .ip4_u =
 705                                               { .daddr = dst,
 706                                                 .saddr = tiph->saddr,
 707                                                 .tos = RT_TOS(tos) } },
 708                                     .oif = tunnel->parms.link,
 709                                     .proto = IPPROTO_IPV6 };
 710                 if (ip_route_output_key(dev_net(dev), &rt, &fl)) {
 711                         stats->tx_carrier_errors++;
 712                         goto tx_error_icmp;
 713                 }
 714         }
 715         if (rt->rt_type != RTN_UNICAST) {
 716                 ip_rt_put(rt);
 717                 stats->tx_carrier_errors++;
 718                 goto tx_error_icmp;
 719         }
 720         tdev = rt->u.dst.dev;
 721
 722         if (tdev == dev) {
 723                 ip_rt_put(rt);
 724                 stats->collisions++;
 725                 goto tx_error;
 726         }
 727
 728         if (df) {
 729                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 730
 731                 if (mtu < 68) {
 732                         stats->collisions++;
 733                         ip_rt_put(rt);
 734                         goto tx_error;
 735                 }
 736
 737                 if (mtu < IPV6_MIN_MTU) {
 738                         mtu = IPV6_MIN_MTU;
 739                         df = 0;
 740                 }
 741
 742                 if (tunnel->parms.iph.daddr && skb_dst(skb))
 743                         skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 744
 745                 if (skb->len > mtu) {
 746                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 747                         ip_rt_put(rt);
 748                         goto tx_error;
 749                 }
 750         }
 751
 752         if (tunnel->err_count > 0) {
 753                 if (time_before(jiffies,
 754                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
 755                         tunnel->err_count--;
 756                         dst_link_failure(skb);
 757                 } else
 758                         tunnel->err_count = 0;
 759         }
 760
 761         /*
 762          * Okay, now see if we can stuff it in the buffer as-is.
 763          */
 764         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 765
 766         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 767             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 768                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 769                 if (!new_skb) {
 770                         ip_rt_put(rt);
 771                         txq->tx_dropped++;
 772                         dev_kfree_skb(skb);
 773                         return NETDEV_TX_OK;
 774                 }
 775                 if (skb->sk)
 776                         skb_set_owner_w(new_skb, skb->sk);
 777                 dev_kfree_skb(skb);
 778                 skb = new_skb;
 779                 iph6 = ipv6_hdr(skb);
 780         }
 781
 782         skb->transport_header = skb->network_header;
 783         skb_push(skb, sizeof(struct iphdr));
 784         skb_reset_network_header(skb);
 785         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 786         IPCB(skb)->flags = 0;
 787         skb_dst_drop(skb);
 788         skb_dst_set(skb, &rt->u.dst);
 789
 790         /*
 791          *      Push down and install the IPIP header.
 792          */
 793
 794         iph                     =       ip_hdr(skb);
 795         iph->version            =       4;
 796         iph->ihl                =       sizeof(struct iphdr)>>2;
 797         iph->frag_off           =       df;
 798         iph->protocol           =       IPPROTO_IPV6;
 799         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 800         iph->daddr              =       rt->rt_dst;
 801         iph->saddr              =       rt->rt_src;
 802
 803         if ((iph->ttl = tiph->ttl) == 0)
 804                 iph->ttl        =       iph6->hop_limit;
 805
 806         nf_reset(skb);
 807
 808         IPTUNNEL_XMIT();
 809         return NETDEV_TX_OK;
 810
 811 tx_error_icmp:
 812         dst_link_failure(skb);
 813 tx_error:
 814         stats->tx_errors++;
 815         dev_kfree_skb(skb);
 816         return NETDEV_TX_OK;
 817 }
 818
 819 static void ipip6_tunnel_bind_dev(struct net_device *dev)
 820 {
 821         struct net_device *tdev = NULL;
 822         struct ip_tunnel *tunnel;
 823         struct iphdr *iph;
 824
 825         tunnel = netdev_priv(dev);
 826         iph = &tunnel->parms.iph;
 827
 828         if (iph->daddr) {
 829                 struct flowi fl = { .nl_u = { .ip4_u =
 830                                               { .daddr = iph->daddr,
 831                                                 .saddr = iph->saddr,
 832                                                 .tos = RT_TOS(iph->tos) } },
 833                                     .oif = tunnel->parms.link,
 834                                     .proto = IPPROTO_IPV6 };
 835                 struct rtable *rt;
 836                 if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 837                         tdev = rt->u.dst.dev;
 838                         ip_rt_put(rt);
 839                 }
 840                 dev->flags |= IFF_POINTOPOINT;
 841         }
 842
 843         if (!tdev && tunnel->parms.link)
 844                 tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);
 845
 846         if (tdev) {
 847                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 848                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 849                 if (dev->mtu < IPV6_MIN_MTU)
 850                         dev->mtu = IPV6_MIN_MTU;
 851         }
 852         dev->iflink = tunnel->parms.link;
 853 }
 854
 855 static int
 856 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 857 {
 858         int err = 0;
 859         struct ip_tunnel_parm p;
 860         struct ip_tunnel_prl prl;
 861         struct ip_tunnel *t;
 862         struct net *net = dev_net(dev);
 863         struct sit_net *sitn = net_generic(net, sit_net_id);
 864 #ifdef CONFIG_IPV6_SIT_6RD
 865         struct ip_tunnel_6rd ip6rd;
 866 #endif
 867
 868         switch (cmd) {
 869         case SIOCGETTUNNEL:
 870 #ifdef CONFIG_IPV6_SIT_6RD
 871         case SIOCGET6RD:
 872 #endif
 873                 t = NULL;
 874                 if (dev == sitn->fb_tunnel_dev) {
 875                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 876                                 err = -EFAULT;
 877                                 break;
 878                         }
 879                         t = ipip6_tunnel_locate(net, &p, 0);
 880                 }
 881                 if (t == NULL)
 882                         t = netdev_priv(dev);
 883
 884                 err = -EFAULT;
 885                 if (cmd == SIOCGETTUNNEL) {
 886                         memcpy(&p, &t->parms, sizeof(p));
 887                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p,
 888                                          sizeof(p)))
 889                                 goto done;
 890 #ifdef CONFIG_IPV6_SIT_6RD
 891                 } else {
 892                         ipv6_addr_copy(&ip6rd.prefix, &t->ip6rd.prefix);
 893                         ip6rd.relay_prefix = t->ip6rd.relay_prefix;
 894                         ip6rd.prefixlen = t->ip6rd.prefixlen;
 895                         ip6rd.relay_prefixlen = t->ip6rd.relay_prefixlen;
 896                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &ip6rd,
 897                                          sizeof(ip6rd)))
 898                                 goto done;
 899 #endif
 900                 }
 901                 err = 0;
 902                 break;
 903
 904         case SIOCADDTUNNEL:
 905         case SIOCCHGTUNNEL:
 906                 err = -EPERM;
 907                 if (!capable(CAP_NET_ADMIN))
 908                         goto done;
 909
 910                 err = -EFAULT;
 911                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 912                         goto done;
 913
 914                 err = -EINVAL;
 915                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 916                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 917                         goto done;
 918                 if (p.iph.ttl)
 919                         p.iph.frag_off |= htons(IP_DF);
 920
 921                 t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
 922
 923                 if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 924                         if (t != NULL) {
 925                                 if (t->dev != dev) {
 926                                         err = -EEXIST;
 927                                         break;
 928                                 }
 929                         } else {
 930                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 931                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 932                                         err = -EINVAL;
 933                                         break;
 934                                 }
 935                                 t = netdev_priv(dev);
 936                                 ipip6_tunnel_unlink(sitn, t);
 937                                 t->parms.iph.saddr = p.iph.saddr;
 938                                 t->parms.iph.daddr = p.iph.daddr;
 939                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 940                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 941                                 ipip6_tunnel_link(sitn, t);
 942                                 netdev_state_change(dev);
 943                         }
 944                 }
 945
 946                 if (t) {
 947                         err = 0;
 948                         if (cmd == SIOCCHGTUNNEL) {
 949                                 t->parms.iph.ttl = p.iph.ttl;
 950                                 t->parms.iph.tos = p.iph.tos;
 951                                 if (t->parms.link != p.link) {
 952                                         t->parms.link = p.link;
 953                                         ipip6_tunnel_bind_dev(dev);
 954                                         netdev_state_change(dev);
 955                                 }
 956                         }
 957                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 958                                 err = -EFAULT;
 959                 } else
 960                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 961                 break;
 962
 963         case SIOCDELTUNNEL:
 964                 err = -EPERM;
 965                 if (!capable(CAP_NET_ADMIN))
 966                         goto done;
 967
 968                 if (dev == sitn->fb_tunnel_dev) {
 969                         err = -EFAULT;
 970                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 971                                 goto done;
 972                         err = -ENOENT;
 973                         if ((t = ipip6_tunnel_locate(net, &p, 0)) == NULL)
 974                                 goto done;
 975                         err = -EPERM;
 976                         if (t == netdev_priv(sitn->fb_tunnel_dev))
 977                                 goto done;
 978                         dev = t->dev;
 979                 }
 980                 unregister_netdevice(dev);
 981                 err = 0;
 982                 break;
 983
 984         case SIOCGETPRL:
 985                 err = -EINVAL;
 986                 if (dev == sitn->fb_tunnel_dev)
 987                         goto done;
 988                 err = -ENOENT;
 989                 if (!(t = netdev_priv(dev)))
 990                         goto done;
 991                 err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
 992                 break;
 993
 994         case SIOCADDPRL:
 995         case SIOCDELPRL:
 996         case SIOCCHGPRL:
 997                 err = -EPERM;
 998                 if (!capable(CAP_NET_ADMIN))
 999                         goto done;
1000                 err = -EINVAL;
1001                 if (dev == sitn->fb_tunnel_dev)
1002                         goto done;
1003                 err = -EFAULT;
1004                 if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
1005                         goto done;
1006                 err = -ENOENT;
1007                 if (!(t = netdev_priv(dev)))
1008                         goto done;
1009
1010                 switch (cmd) {
1011                 case SIOCDELPRL:
1012                         err = ipip6_tunnel_del_prl(t, &prl);
1013                         break;
1014                 case SIOCADDPRL:
1015                 case SIOCCHGPRL:
1016                         err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
1017                         break;
1018                 }
1019                 netdev_state_change(dev);
1020                 break;
1021
1022 #ifdef CONFIG_IPV6_SIT_6RD
1023         case SIOCADD6RD:
1024         case SIOCCHG6RD:
1025         case SIOCDEL6RD:
1026                 err = -EPERM;
1027                 if (!capable(CAP_NET_ADMIN))
1028                         goto done;
1029
1030                 err = -EFAULT;
1031                 if (copy_from_user(&ip6rd, ifr->ifr_ifru.ifru_data,
1032                                    sizeof(ip6rd)))
1033                         goto done;
1034
1035                 t = netdev_priv(dev);
1036
1037                 if (cmd != SIOCDEL6RD) {
1038                         struct in6_addr prefix;
1039                         __be32 relay_prefix;
1040
1041                         err = -EINVAL;
1042                         if (ip6rd.relay_prefixlen > 32 ||
1043                             ip6rd.prefixlen + (32 - ip6rd.relay_prefixlen) > 64)
1044                                 goto done;
1045
1046                         ipv6_addr_prefix(&prefix, &ip6rd.prefix,
1047                                          ip6rd.prefixlen);
1048                         if (!ipv6_addr_equal(&prefix, &ip6rd.prefix))
1049                                 goto done;
1050                         if (ip6rd.relay_prefixlen)
1051                                 relay_prefix = ip6rd.relay_prefix &
1052                                                htonl(0xffffffffUL <<
1053                                                      (32 - ip6rd.relay_prefixlen));
1054                         else
1055                                 relay_prefix = 0;
1056                         if (relay_prefix != ip6rd.relay_prefix)
1057                                 goto done;
1058
1059                         ipv6_addr_copy(&t->ip6rd.prefix, &prefix);
1060                         t->ip6rd.relay_prefix = relay_prefix;
1061                         t->ip6rd.prefixlen = ip6rd.prefixlen;
1062                         t->ip6rd.relay_prefixlen = ip6rd.relay_prefixlen;
1063                 } else
1064                         ipip6_tunnel_clone_6rd(dev, sitn);
1065
1066                 err = 0;
1067                 break;
1068 #endif
1069
1070         default:
1071                 err = -EINVAL;
1072         }
1073
1074 done:
1075         return err;
1076 }
1077
1078 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1079 {
1080         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
1081                 return -EINVAL;
1082         dev->mtu = new_mtu;
1083         return 0;
1084 }
1085
1086 static const struct net_device_ops ipip6_netdev_ops = {
1087         .ndo_uninit     = ipip6_tunnel_uninit,
1088         .ndo_start_xmit = ipip6_tunnel_xmit,
1089         .ndo_do_ioctl   = ipip6_tunnel_ioctl,
1090         .ndo_change_mtu = ipip6_tunnel_change_mtu,
1091 };
1092
1093 static void ipip6_tunnel_setup(struct net_device *dev)
1094 {
1095         dev->netdev_ops         = &ipip6_netdev_ops;
1096         dev->destructor         = free_netdev;
1097
1098         dev->type               = ARPHRD_SIT;
1099         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
1100         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
1101         dev->flags              = IFF_NOARP;
1102         dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
1103         dev->iflink             = 0;
1104         dev->addr_len           = 4;
1105         dev->features           |= NETIF_F_NETNS_LOCAL;
1106 }
1107
1108 static void ipip6_tunnel_init(struct net_device *dev)
1109 {
1110         struct ip_tunnel *tunnel = netdev_priv(dev);
1111
1112         tunnel->dev = dev;
1113         strcpy(tunnel->parms.name, dev->name);
1114
1115         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1116         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1117
1118         ipip6_tunnel_bind_dev(dev);
1119 }
1120
1121 static void __net_init ipip6_fb_tunnel_init(struct net_device *dev)
1122 {
1123         struct ip_tunnel *tunnel = netdev_priv(dev);
1124         struct iphdr *iph = &tunnel->parms.iph;
1125         struct net *net = dev_net(dev);
1126         struct sit_net *sitn = net_generic(net, sit_net_id);
1127
1128         tunnel->dev = dev;
1129         strcpy(tunnel->parms.name, dev->name);
1130
1131         iph->version            = 4;
1132         iph->protocol           = IPPROTO_IPV6;
1133         iph->ihl                = 5;
1134         iph->ttl                = 64;
1135
1136         dev_hold(dev);
1137         sitn->tunnels_wc[0]     = tunnel;
1138 }
1139
1140 static struct xfrm_tunnel sit_handler = {
1141         .handler        =       ipip6_rcv,
1142         .err_handler    =       ipip6_err,
1143         .priority       =       1,
1144 };
1145
1146 static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_head *head)
1147 {
1148         int prio;
1149
1150         for (prio = 1; prio < 4; prio++) {
1151                 int h;
1152                 for (h = 0; h < HASH_SIZE; h++) {
1153                         struct ip_tunnel *t = sitn->tunnels[prio][h];
1154
1155                         while (t != NULL) {
1156                                 unregister_netdevice_queue(t->dev, head);
1157                                 t = t->next;
1158                         }
1159                 }
1160         }
1161 }
1162
1163 static int __net_init sit_init_net(struct net *net)
1164 {
1165         struct sit_net *sitn = net_generic(net, sit_net_id);
1166         int err;
1167
1168         sitn->tunnels[0] = sitn->tunnels_wc;
1169         sitn->tunnels[1] = sitn->tunnels_l;
1170         sitn->tunnels[2] = sitn->tunnels_r;
1171         sitn->tunnels[3] = sitn->tunnels_r_l;
1172
1173         sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
1174                                            ipip6_tunnel_setup);
1175         if (!sitn->fb_tunnel_dev) {
1176                 err = -ENOMEM;
1177                 goto err_alloc_dev;
1178         }
1179         dev_net_set(sitn->fb_tunnel_dev, net);
1180
1181         ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
1182         ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
1183
1184         if ((err = register_netdev(sitn->fb_tunnel_dev)))
1185                 goto err_reg_dev;
1186
1187         return 0;
1188
1189 err_reg_dev:
1190         dev_put(sitn->fb_tunnel_dev);
1191         free_netdev(sitn->fb_tunnel_dev);
1192 err_alloc_dev:
1193         return err;
1194 }
1195
1196 static void __net_exit sit_exit_net(struct net *net)
1197 {
1198         struct sit_net *sitn = net_generic(net, sit_net_id);
1199         LIST_HEAD(list);
1200
1201         rtnl_lock();
1202         sit_destroy_tunnels(sitn, &list);
1203         unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);
1204         unregister_netdevice_many(&list);
1205         rtnl_unlock();
1206 }
1207
1208 static struct pernet_operations sit_net_ops = {
1209         .init = sit_init_net,
1210         .exit = sit_exit_net,
1211         .id   = &sit_net_id,
1212         .size = sizeof(struct sit_net),
1213 };
1214
1215 static void __exit sit_cleanup(void)
1216 {
1217         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1218
1219         unregister_pernet_device(&sit_net_ops);
1220         rcu_barrier(); /* Wait for completion of call_rcu()'s */
1221 }
1222
1223 static int __init sit_init(void)
1224 {
1225         int err;
1226
1227         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
1228
1229         err = register_pernet_device(&sit_net_ops);
1230         if (err < 0)
1231                 return err;
1232         err = xfrm4_tunnel_register(&sit_handler, AF_INET6);
1233         if (err < 0) {
1234                 unregister_pernet_device(&sit_net_ops);
1235                 printk(KERN_INFO "sit init: Can't add protocol\n");
1236         }
1237         return err;
1238 }
1239
1240 module_init(sit_init);
1241 module_exit(sit_cleanup);
1242 MODULE_LICENSE("GPL");
1243 MODULE_ALIAS("sit0");