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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         INIT_RCU_HEAD(&p->rcu_head);
 367         p->next = t->prl;
 368         p->addr = a->addr;
 369         p->flags = a->flags;
 370         t->prl_count++;
 371         rcu_assign_pointer(t->prl, p);
 372 out:
 373         spin_unlock(&ipip6_prl_lock);
 374         return err;
 375 }
 376
 377 static void prl_entry_destroy_rcu(struct rcu_head *head)
 378 {
 379         kfree(container_of(head, struct ip_tunnel_prl_entry, rcu_head));
 380 }
 381
 382 static void prl_list_destroy_rcu(struct rcu_head *head)
 383 {
 384         struct ip_tunnel_prl_entry *p, *n;
 385
 386         p = container_of(head, struct ip_tunnel_prl_entry, rcu_head);
 387         do {
 388                 n = p->next;
 389                 kfree(p);
 390                 p = n;
 391         } while (p);
 392 }
 393
 394 static int
 395 ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
 396 {
 397         struct ip_tunnel_prl_entry *x, **p;
 398         int err = 0;
 399
 400         spin_lock(&ipip6_prl_lock);
 401
 402         if (a && a->addr != htonl(INADDR_ANY)) {
 403                 for (p = &t->prl; *p; p = &(*p)->next) {
 404                         if ((*p)->addr == a->addr) {
 405                                 x = *p;
 406                                 *p = x->next;
 407                                 call_rcu(&x->rcu_head, prl_entry_destroy_rcu);
 408                                 t->prl_count--;
 409                                 goto out;
 410                         }
 411                 }
 412                 err = -ENXIO;
 413         } else {
 414                 if (t->prl) {
 415                         t->prl_count = 0;
 416                         x = t->prl;
 417                         call_rcu(&x->rcu_head, prl_list_destroy_rcu);
 418                         t->prl = NULL;
 419                 }
 420         }
 421 out:
 422         spin_unlock(&ipip6_prl_lock);
 423         return err;
 424 }
 425
 426 static int
 427 isatap_chksrc(struct sk_buff *skb, struct iphdr *iph, struct ip_tunnel *t)
 428 {
 429         struct ip_tunnel_prl_entry *p;
 430         int ok = 1;
 431
 432         rcu_read_lock();
 433         p = __ipip6_tunnel_locate_prl(t, iph->saddr);
 434         if (p) {
 435                 if (p->flags & PRL_DEFAULT)
 436                         skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
 437                 else
 438                         skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
 439         } else {
 440                 struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
 441                 if (ipv6_addr_is_isatap(addr6) &&
 442                     (addr6->s6_addr32[3] == iph->saddr) &&
 443                     ipv6_chk_prefix(addr6, t->dev))
 444                         skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
 445                 else
 446                         ok = 0;
 447         }
 448         rcu_read_unlock();
 449         return ok;
 450 }
 451
 452 static void ipip6_tunnel_uninit(struct net_device *dev)
 453 {
 454         struct net *net = dev_net(dev);
 455         struct sit_net *sitn = net_generic(net, sit_net_id);
 456
 457         if (dev == sitn->fb_tunnel_dev) {
 458                 spin_lock_bh(&ipip6_lock);
 459                 sitn->tunnels_wc[0] = NULL;
 460                 spin_unlock_bh(&ipip6_lock);
 461                 dev_put(dev);
 462         } else {
 463                 ipip6_tunnel_unlink(sitn, netdev_priv(dev));
 464                 ipip6_tunnel_del_prl(netdev_priv(dev), NULL);
 465                 dev_put(dev);
 466         }
 467 }
 468
 469
 470 static int ipip6_err(struct sk_buff *skb, u32 info)
 471 {
 472
 473 /* All the routers (except for Linux) return only
 474    8 bytes of packet payload. It means, that precise relaying of
 475    ICMP in the real Internet is absolutely infeasible.
 476  */
 477         struct iphdr *iph = (struct iphdr*)skb->data;
 478         const int type = icmp_hdr(skb)->type;
 479         const int code = icmp_hdr(skb)->code;
 480         struct ip_tunnel *t;
 481         int err;
 482
 483         switch (type) {
 484         default:
 485         case ICMP_PARAMETERPROB:
 486                 return 0;
 487
 488         case ICMP_DEST_UNREACH:
 489                 switch (code) {
 490                 case ICMP_SR_FAILED:
 491                 case ICMP_PORT_UNREACH:
 492                         /* Impossible event. */
 493                         return 0;
 494                 case ICMP_FRAG_NEEDED:
 495                         /* Soft state for pmtu is maintained by IP core. */
 496                         return 0;
 497                 default:
 498                         /* All others are translated to HOST_UNREACH.
 499                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 500                            I believe they are just ether pollution. --ANK
 501                          */
 502                         break;
 503                 }
 504                 break;
 505         case ICMP_TIME_EXCEEDED:
 506                 if (code != ICMP_EXC_TTL)
 507                         return 0;
 508                 break;
 509         }
 510
 511         err = -ENOENT;
 512
 513         rcu_read_lock();
 514         t = ipip6_tunnel_lookup(dev_net(skb->dev),
 515                                 skb->dev,
 516                                 iph->daddr,
 517                                 iph->saddr);
 518         if (t == NULL || t->parms.iph.daddr == 0)
 519                 goto out;
 520
 521         err = 0;
 522         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 523                 goto out;
 524
 525         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
 526                 t->err_count++;
 527         else
 528                 t->err_count = 1;
 529         t->err_time = jiffies;
 530 out:
 531         rcu_read_unlock();
 532         return err;
 533 }
 534
 535 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 536 {
 537         if (INET_ECN_is_ce(iph->tos))
 538                 IP6_ECN_set_ce(ipv6_hdr(skb));
 539 }
 540
 541 static int ipip6_rcv(struct sk_buff *skb)
 542 {
 543         struct iphdr *iph;
 544         struct ip_tunnel *tunnel;
 545
 546         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 547                 goto out;
 548
 549         iph = ip_hdr(skb);
 550
 551         rcu_read_lock();
 552         tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
 553                                      iph->saddr, iph->daddr);
 554         if (tunnel != NULL) {
 555                 secpath_reset(skb);
 556                 skb->mac_header = skb->network_header;
 557                 skb_reset_network_header(skb);
 558                 IPCB(skb)->flags = 0;
 559                 skb->protocol = htons(ETH_P_IPV6);
 560                 skb->pkt_type = PACKET_HOST;
 561
 562                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
 563                     !isatap_chksrc(skb, iph, tunnel)) {
 564                         tunnel->dev->stats.rx_errors++;
 565                         rcu_read_unlock();
 566                         kfree_skb(skb);
 567                         return 0;
 568                 }
 569                 tunnel->dev->stats.rx_packets++;
 570                 tunnel->dev->stats.rx_bytes += skb->len;
 571                 skb->dev = tunnel->dev;
 572                 skb_dst_drop(skb);
 573                 nf_reset(skb);
 574                 ipip6_ecn_decapsulate(iph, skb);
 575                 netif_rx(skb);
 576                 rcu_read_unlock();
 577                 return 0;
 578         }
 579
 580         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 581         rcu_read_unlock();
 582 out:
 583         kfree_skb(skb);
 584         return 0;
 585 }
 586
 587 /*
 588  * Returns the embedded IPv4 address if the IPv6 address
 589  * comes from 6rd / 6to4 (RFC 3056) addr space.
 590  */
 591 static inline
 592 __be32 try_6rd(struct in6_addr *v6dst, struct ip_tunnel *tunnel)
 593 {
 594         __be32 dst = 0;
 595
 596 #ifdef CONFIG_IPV6_SIT_6RD
 597         if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
 598                               tunnel->ip6rd.prefixlen)) {
 599                 unsigned pbw0, pbi0;
 600                 int pbi1;
 601                 u32 d;
 602
 603                 pbw0 = tunnel->ip6rd.prefixlen >> 5;
 604                 pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
 605
 606                 d = (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
 607                     tunnel->ip6rd.relay_prefixlen;
 608
 609                 pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
 610                 if (pbi1 > 0)
 611                         d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
 612                              (32 - pbi1);
 613
 614                 dst = tunnel->ip6rd.relay_prefix | htonl(d);
 615         }
 616 #else
 617         if (v6dst->s6_addr16[0] == htons(0x2002)) {
 618                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
 619                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
 620         }
 621 #endif
 622         return dst;
 623 }
 624
 625 /*
 626  *      This function assumes it is being called from dev_queue_xmit()
 627  *      and that skb is filled properly by that function.
 628  */
 629
 630 static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 631                                      struct net_device *dev)
 632 {
 633         struct ip_tunnel *tunnel = netdev_priv(dev);
 634         struct net_device_stats *stats = &dev->stats;
 635         struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
 636         struct iphdr  *tiph = &tunnel->parms.iph;
 637         struct ipv6hdr *iph6 = ipv6_hdr(skb);
 638         u8     tos = tunnel->parms.iph.tos;
 639         __be16 df = tiph->frag_off;
 640         struct rtable *rt;                      /* Route to the other host */
 641         struct net_device *tdev;                        /* Device to other host */
 642         struct iphdr  *iph;                     /* Our new IP header */
 643         unsigned int max_headroom;              /* The extra header space needed */
 644         __be32 dst = tiph->daddr;
 645         int    mtu;
 646         struct in6_addr *addr6;
 647         int addr_type;
 648
 649         if (skb->protocol != htons(ETH_P_IPV6))
 650                 goto tx_error;
 651
 652         /* ISATAP (RFC4214) - must come before 6to4 */
 653         if (dev->priv_flags & IFF_ISATAP) {
 654                 struct neighbour *neigh = NULL;
 655
 656                 if (skb_dst(skb))
 657                         neigh = skb_dst(skb)->neighbour;
 658
 659                 if (neigh == NULL) {
 660                         if (net_ratelimit())
 661                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 662                         goto tx_error;
 663                 }
 664
 665                 addr6 = (struct in6_addr*)&neigh->primary_key;
 666                 addr_type = ipv6_addr_type(addr6);
 667
 668                 if ((addr_type & IPV6_ADDR_UNICAST) &&
 669                      ipv6_addr_is_isatap(addr6))
 670                         dst = addr6->s6_addr32[3];
 671                 else
 672                         goto tx_error;
 673         }
 674
 675         if (!dst)
 676                 dst = try_6rd(&iph6->daddr, tunnel);
 677
 678         if (!dst) {
 679                 struct neighbour *neigh = NULL;
 680
 681                 if (skb_dst(skb))
 682                         neigh = skb_dst(skb)->neighbour;
 683
 684                 if (neigh == NULL) {
 685                         if (net_ratelimit())
 686                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
 687                         goto tx_error;
 688                 }
 689
 690                 addr6 = (struct in6_addr*)&neigh->primary_key;
 691                 addr_type = ipv6_addr_type(addr6);
 692
 693                 if (addr_type == IPV6_ADDR_ANY) {
 694                         addr6 = &ipv6_hdr(skb)->daddr;
 695                         addr_type = ipv6_addr_type(addr6);
 696                 }
 697
 698                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 699                         goto tx_error_icmp;
 700
 701                 dst = addr6->s6_addr32[3];
 702         }
 703
 704         {
 705                 struct flowi fl = { .nl_u = { .ip4_u =
 706                                               { .daddr = dst,
 707                                                 .saddr = tiph->saddr,
 708                                                 .tos = RT_TOS(tos) } },
 709                                     .oif = tunnel->parms.link,
 710                                     .proto = IPPROTO_IPV6 };
 711                 if (ip_route_output_key(dev_net(dev), &rt, &fl)) {
 712                         stats->tx_carrier_errors++;
 713                         goto tx_error_icmp;
 714                 }
 715         }
 716         if (rt->rt_type != RTN_UNICAST) {
 717                 ip_rt_put(rt);
 718                 stats->tx_carrier_errors++;
 719                 goto tx_error_icmp;
 720         }
 721         tdev = rt->u.dst.dev;
 722
 723         if (tdev == dev) {
 724                 ip_rt_put(rt);
 725                 stats->collisions++;
 726                 goto tx_error;
 727         }
 728
 729         if (df) {
 730                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 731
 732                 if (mtu < 68) {
 733                         stats->collisions++;
 734                         ip_rt_put(rt);
 735                         goto tx_error;
 736                 }
 737
 738                 if (mtu < IPV6_MIN_MTU) {
 739                         mtu = IPV6_MIN_MTU;
 740                         df = 0;
 741                 }
 742
 743                 if (tunnel->parms.iph.daddr && skb_dst(skb))
 744                         skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 745
 746                 if (skb->len > mtu) {
 747                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 748                         ip_rt_put(rt);
 749                         goto tx_error;
 750                 }
 751         }
 752
 753         if (tunnel->err_count > 0) {
 754                 if (time_before(jiffies,
 755                                 tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
 756                         tunnel->err_count--;
 757                         dst_link_failure(skb);
 758                 } else
 759                         tunnel->err_count = 0;
 760         }
 761
 762         /*
 763          * Okay, now see if we can stuff it in the buffer as-is.
 764          */
 765         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
 766
 767         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 768             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 769                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 770                 if (!new_skb) {
 771                         ip_rt_put(rt);
 772                         txq->tx_dropped++;
 773                         dev_kfree_skb(skb);
 774                         return NETDEV_TX_OK;
 775                 }
 776                 if (skb->sk)
 777                         skb_set_owner_w(new_skb, skb->sk);
 778                 dev_kfree_skb(skb);
 779                 skb = new_skb;
 780                 iph6 = ipv6_hdr(skb);
 781         }
 782
 783         skb->transport_header = skb->network_header;
 784         skb_push(skb, sizeof(struct iphdr));
 785         skb_reset_network_header(skb);
 786         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 787         IPCB(skb)->flags = 0;
 788         skb_dst_drop(skb);
 789         skb_dst_set(skb, &rt->u.dst);
 790
 791         /*
 792          *      Push down and install the IPIP header.
 793          */
 794
 795         iph                     =       ip_hdr(skb);
 796         iph->version            =       4;
 797         iph->ihl                =       sizeof(struct iphdr)>>2;
 798         iph->frag_off           =       df;
 799         iph->protocol           =       IPPROTO_IPV6;
 800         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 801         iph->daddr              =       rt->rt_dst;
 802         iph->saddr              =       rt->rt_src;
 803
 804         if ((iph->ttl = tiph->ttl) == 0)
 805                 iph->ttl        =       iph6->hop_limit;
 806
 807         nf_reset(skb);
 808
 809         IPTUNNEL_XMIT();
 810         return NETDEV_TX_OK;
 811
 812 tx_error_icmp:
 813         dst_link_failure(skb);
 814 tx_error:
 815         stats->tx_errors++;
 816         dev_kfree_skb(skb);
 817         return NETDEV_TX_OK;
 818 }
 819
 820 static void ipip6_tunnel_bind_dev(struct net_device *dev)
 821 {
 822         struct net_device *tdev = NULL;
 823         struct ip_tunnel *tunnel;
 824         struct iphdr *iph;
 825
 826         tunnel = netdev_priv(dev);
 827         iph = &tunnel->parms.iph;
 828
 829         if (iph->daddr) {
 830                 struct flowi fl = { .nl_u = { .ip4_u =
 831                                               { .daddr = iph->daddr,
 832                                                 .saddr = iph->saddr,
 833                                                 .tos = RT_TOS(iph->tos) } },
 834                                     .oif = tunnel->parms.link,
 835                                     .proto = IPPROTO_IPV6 };
 836                 struct rtable *rt;
 837                 if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 838                         tdev = rt->u.dst.dev;
 839                         ip_rt_put(rt);
 840                 }
 841                 dev->flags |= IFF_POINTOPOINT;
 842         }
 843
 844         if (!tdev && tunnel->parms.link)
 845                 tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);
 846
 847         if (tdev) {
 848                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 849                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 850                 if (dev->mtu < IPV6_MIN_MTU)
 851                         dev->mtu = IPV6_MIN_MTU;
 852         }
 853         dev->iflink = tunnel->parms.link;
 854 }
 855
 856 static int
 857 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 858 {
 859         int err = 0;
 860         struct ip_tunnel_parm p;
 861         struct ip_tunnel_prl prl;
 862         struct ip_tunnel *t;
 863         struct net *net = dev_net(dev);
 864         struct sit_net *sitn = net_generic(net, sit_net_id);
 865 #ifdef CONFIG_IPV6_SIT_6RD
 866         struct ip_tunnel_6rd ip6rd;
 867 #endif
 868
 869         switch (cmd) {
 870         case SIOCGETTUNNEL:
 871 #ifdef CONFIG_IPV6_SIT_6RD
 872         case SIOCGET6RD:
 873 #endif
 874                 t = NULL;
 875                 if (dev == sitn->fb_tunnel_dev) {
 876                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 877                                 err = -EFAULT;
 878                                 break;
 879                         }
 880                         t = ipip6_tunnel_locate(net, &p, 0);
 881                 }
 882                 if (t == NULL)
 883                         t = netdev_priv(dev);
 884
 885                 err = -EFAULT;
 886                 if (cmd == SIOCGETTUNNEL) {
 887                         memcpy(&p, &t->parms, sizeof(p));
 888                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p,
 889                                          sizeof(p)))
 890                                 goto done;
 891 #ifdef CONFIG_IPV6_SIT_6RD
 892                 } else {
 893                         ipv6_addr_copy(&ip6rd.prefix, &t->ip6rd.prefix);
 894                         ip6rd.relay_prefix = t->ip6rd.relay_prefix;
 895                         ip6rd.prefixlen = t->ip6rd.prefixlen;
 896                         ip6rd.relay_prefixlen = t->ip6rd.relay_prefixlen;
 897                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &ip6rd,
 898                                          sizeof(ip6rd)))
 899                                 goto done;
 900 #endif
 901                 }
 902                 err = 0;
 903                 break;
 904
 905         case SIOCADDTUNNEL:
 906         case SIOCCHGTUNNEL:
 907                 err = -EPERM;
 908                 if (!capable(CAP_NET_ADMIN))
 909                         goto done;
 910
 911                 err = -EFAULT;
 912                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 913                         goto done;
 914
 915                 err = -EINVAL;
 916                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
 917                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 918                         goto done;
 919                 if (p.iph.ttl)
 920                         p.iph.frag_off |= htons(IP_DF);
 921
 922                 t = ipip6_tunnel_locate(net, &p, cmd == SIOCADDTUNNEL);
 923
 924                 if (dev != sitn->fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 925                         if (t != NULL) {
 926                                 if (t->dev != dev) {
 927                                         err = -EEXIST;
 928                                         break;
 929                                 }
 930                         } else {
 931                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 932                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 933                                         err = -EINVAL;
 934                                         break;
 935                                 }
 936                                 t = netdev_priv(dev);
 937                                 ipip6_tunnel_unlink(sitn, t);
 938                                 t->parms.iph.saddr = p.iph.saddr;
 939                                 t->parms.iph.daddr = p.iph.daddr;
 940                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 941                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 942                                 ipip6_tunnel_link(sitn, t);
 943                                 netdev_state_change(dev);
 944                         }
 945                 }
 946
 947                 if (t) {
 948                         err = 0;
 949                         if (cmd == SIOCCHGTUNNEL) {
 950                                 t->parms.iph.ttl = p.iph.ttl;
 951                                 t->parms.iph.tos = p.iph.tos;
 952                                 if (t->parms.link != p.link) {
 953                                         t->parms.link = p.link;
 954                                         ipip6_tunnel_bind_dev(dev);
 955                                         netdev_state_change(dev);
 956                                 }
 957                         }
 958                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 959                                 err = -EFAULT;
 960                 } else
 961                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 962                 break;
 963
 964         case SIOCDELTUNNEL:
 965                 err = -EPERM;
 966                 if (!capable(CAP_NET_ADMIN))
 967                         goto done;
 968
 969                 if (dev == sitn->fb_tunnel_dev) {
 970                         err = -EFAULT;
 971                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 972                                 goto done;
 973                         err = -ENOENT;
 974                         if ((t = ipip6_tunnel_locate(net, &p, 0)) == NULL)
 975                                 goto done;
 976                         err = -EPERM;
 977                         if (t == netdev_priv(sitn->fb_tunnel_dev))
 978                                 goto done;
 979                         dev = t->dev;
 980                 }
 981                 unregister_netdevice(dev);
 982                 err = 0;
 983                 break;
 984
 985         case SIOCGETPRL:
 986                 err = -EINVAL;
 987                 if (dev == sitn->fb_tunnel_dev)
 988                         goto done;
 989                 err = -ENOENT;
 990                 if (!(t = netdev_priv(dev)))
 991                         goto done;
 992                 err = ipip6_tunnel_get_prl(t, ifr->ifr_ifru.ifru_data);
 993                 break;
 994
 995         case SIOCADDPRL:
 996         case SIOCDELPRL:
 997         case SIOCCHGPRL:
 998                 err = -EPERM;
 999                 if (!capable(CAP_NET_ADMIN))
1000                         goto done;
1001                 err = -EINVAL;
1002                 if (dev == sitn->fb_tunnel_dev)
1003                         goto done;
1004                 err = -EFAULT;
1005                 if (copy_from_user(&prl, ifr->ifr_ifru.ifru_data, sizeof(prl)))
1006                         goto done;
1007                 err = -ENOENT;
1008                 if (!(t = netdev_priv(dev)))
1009                         goto done;
1010
1011                 switch (cmd) {
1012                 case SIOCDELPRL:
1013                         err = ipip6_tunnel_del_prl(t, &prl);
1014                         break;
1015                 case SIOCADDPRL:
1016                 case SIOCCHGPRL:
1017                         err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
1018                         break;
1019                 }
1020                 netdev_state_change(dev);
1021                 break;
1022
1023 #ifdef CONFIG_IPV6_SIT_6RD
1024         case SIOCADD6RD:
1025         case SIOCCHG6RD:
1026         case SIOCDEL6RD:
1027                 err = -EPERM;
1028                 if (!capable(CAP_NET_ADMIN))
1029                         goto done;
1030
1031                 err = -EFAULT;
1032                 if (copy_from_user(&ip6rd, ifr->ifr_ifru.ifru_data,
1033                                    sizeof(ip6rd)))
1034                         goto done;
1035
1036                 t = netdev_priv(dev);
1037
1038                 if (cmd != SIOCDEL6RD) {
1039                         struct in6_addr prefix;
1040                         __be32 relay_prefix;
1041
1042                         err = -EINVAL;
1043                         if (ip6rd.relay_prefixlen > 32 ||
1044                             ip6rd.prefixlen + (32 - ip6rd.relay_prefixlen) > 64)
1045                                 goto done;
1046
1047                         ipv6_addr_prefix(&prefix, &ip6rd.prefix,
1048                                          ip6rd.prefixlen);
1049                         if (!ipv6_addr_equal(&prefix, &ip6rd.prefix))
1050                                 goto done;
1051                         if (ip6rd.relay_prefixlen)
1052                                 relay_prefix = ip6rd.relay_prefix &
1053                                                htonl(0xffffffffUL <<
1054                                                      (32 - ip6rd.relay_prefixlen));
1055                         else
1056                                 relay_prefix = 0;
1057                         if (relay_prefix != ip6rd.relay_prefix)
1058                                 goto done;
1059
1060                         ipv6_addr_copy(&t->ip6rd.prefix, &prefix);
1061                         t->ip6rd.relay_prefix = relay_prefix;
1062                         t->ip6rd.prefixlen = ip6rd.prefixlen;
1063                         t->ip6rd.relay_prefixlen = ip6rd.relay_prefixlen;
1064                 } else
1065                         ipip6_tunnel_clone_6rd(dev, sitn);
1066
1067                 err = 0;
1068                 break;
1069 #endif
1070
1071         default:
1072                 err = -EINVAL;
1073         }
1074
1075 done:
1076         return err;
1077 }
1078
1079 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1080 {
1081         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
1082                 return -EINVAL;
1083         dev->mtu = new_mtu;
1084         return 0;
1085 }
1086
1087 static const struct net_device_ops ipip6_netdev_ops = {
1088         .ndo_uninit     = ipip6_tunnel_uninit,
1089         .ndo_start_xmit = ipip6_tunnel_xmit,
1090         .ndo_do_ioctl   = ipip6_tunnel_ioctl,
1091         .ndo_change_mtu = ipip6_tunnel_change_mtu,
1092 };
1093
1094 static void ipip6_tunnel_setup(struct net_device *dev)
1095 {
1096         dev->netdev_ops         = &ipip6_netdev_ops;
1097         dev->destructor         = free_netdev;
1098
1099         dev->type               = ARPHRD_SIT;
1100         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
1101         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
1102         dev->flags              = IFF_NOARP;
1103         dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
1104         dev->iflink             = 0;
1105         dev->addr_len           = 4;
1106         dev->features           |= NETIF_F_NETNS_LOCAL;
1107 }
1108
1109 static void ipip6_tunnel_init(struct net_device *dev)
1110 {
1111         struct ip_tunnel *tunnel = netdev_priv(dev);
1112
1113         tunnel->dev = dev;
1114         strcpy(tunnel->parms.name, dev->name);
1115
1116         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1117         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1118
1119         ipip6_tunnel_bind_dev(dev);
1120 }
1121
1122 static void __net_init ipip6_fb_tunnel_init(struct net_device *dev)
1123 {
1124         struct ip_tunnel *tunnel = netdev_priv(dev);
1125         struct iphdr *iph = &tunnel->parms.iph;
1126         struct net *net = dev_net(dev);
1127         struct sit_net *sitn = net_generic(net, sit_net_id);
1128
1129         tunnel->dev = dev;
1130         strcpy(tunnel->parms.name, dev->name);
1131
1132         iph->version            = 4;
1133         iph->protocol           = IPPROTO_IPV6;
1134         iph->ihl                = 5;
1135         iph->ttl                = 64;
1136
1137         dev_hold(dev);
1138         sitn->tunnels_wc[0]     = tunnel;
1139 }
1140
1141 static struct xfrm_tunnel sit_handler = {
1142         .handler        =       ipip6_rcv,
1143         .err_handler    =       ipip6_err,
1144         .priority       =       1,
1145 };
1146
1147 static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_head *head)
1148 {
1149         int prio;
1150
1151         for (prio = 1; prio < 4; prio++) {
1152                 int h;
1153                 for (h = 0; h < HASH_SIZE; h++) {
1154                         struct ip_tunnel *t = sitn->tunnels[prio][h];
1155
1156                         while (t != NULL) {
1157                                 unregister_netdevice_queue(t->dev, head);
1158                                 t = t->next;
1159                         }
1160                 }
1161         }
1162 }
1163
1164 static int __net_init sit_init_net(struct net *net)
1165 {
1166         struct sit_net *sitn = net_generic(net, sit_net_id);
1167         int err;
1168
1169         sitn->tunnels[0] = sitn->tunnels_wc;
1170         sitn->tunnels[1] = sitn->tunnels_l;
1171         sitn->tunnels[2] = sitn->tunnels_r;
1172         sitn->tunnels[3] = sitn->tunnels_r_l;
1173
1174         sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
1175                                            ipip6_tunnel_setup);
1176         if (!sitn->fb_tunnel_dev) {
1177                 err = -ENOMEM;
1178                 goto err_alloc_dev;
1179         }
1180         dev_net_set(sitn->fb_tunnel_dev, net);
1181
1182         ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
1183         ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
1184
1185         if ((err = register_netdev(sitn->fb_tunnel_dev)))
1186                 goto err_reg_dev;
1187
1188         return 0;
1189
1190 err_reg_dev:
1191         dev_put(sitn->fb_tunnel_dev);
1192         free_netdev(sitn->fb_tunnel_dev);
1193 err_alloc_dev:
1194         return err;
1195 }
1196
1197 static void __net_exit sit_exit_net(struct net *net)
1198 {
1199         struct sit_net *sitn = net_generic(net, sit_net_id);
1200         LIST_HEAD(list);
1201
1202         rtnl_lock();
1203         sit_destroy_tunnels(sitn, &list);
1204         unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);
1205         unregister_netdevice_many(&list);
1206         rtnl_unlock();
1207 }
1208
1209 static struct pernet_operations sit_net_ops = {
1210         .init = sit_init_net,
1211         .exit = sit_exit_net,
1212         .id   = &sit_net_id,
1213         .size = sizeof(struct sit_net),
1214 };
1215
1216 static void __exit sit_cleanup(void)
1217 {
1218         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1219
1220         unregister_pernet_device(&sit_net_ops);
1221         rcu_barrier(); /* Wait for completion of call_rcu()'s */
1222 }
1223
1224 static int __init sit_init(void)
1225 {
1226         int err;
1227
1228         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
1229
1230         err = register_pernet_device(&sit_net_ops);
1231         if (err < 0)
1232                 return err;
1233         err = xfrm4_tunnel_register(&sit_handler, AF_INET6);
1234         if (err < 0) {
1235                 unregister_pernet_device(&sit_net_ops);
1236                 printk(KERN_INFO "sit init: Can't add protocol\n");
1237         }
1238         return err;
1239 }
1240
1241 module_init(sit_init);
1242 module_exit(sit_cleanup);
1243 MODULE_LICENSE("GPL");
1244 MODULE_ALIAS("sit0");