net/ipv4/ip_gre.c

   1 /*
   2  *      Linux NET3:     GRE over IP protocol decoder.
   3  *
   4  *      Authors: Alexey Kuznetsov (kuznet@ms2.inr.ac.ru)
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  *
  11  */
  12
  13 #include <linux/capability.h>
  14 #include <linux/module.h>
  15 #include <linux/types.h>
  16 #include <linux/sched.h>
  17 #include <linux/kernel.h>
  18 #include <asm/uaccess.h>
  19 #include <linux/skbuff.h>
  20 #include <linux/netdevice.h>
  21 #include <linux/in.h>
  22 #include <linux/tcp.h>
  23 #include <linux/udp.h>
  24 #include <linux/if_arp.h>
  25 #include <linux/mroute.h>
  26 #include <linux/init.h>
  27 #include <linux/in6.h>
  28 #include <linux/inetdevice.h>
  29 #include <linux/igmp.h>
  30 #include <linux/netfilter_ipv4.h>
  31 #include <linux/if_ether.h>
  32
  33 #include <net/sock.h>
  34 #include <net/ip.h>
  35 #include <net/icmp.h>
  36 #include <net/protocol.h>
  37 #include <net/ipip.h>
  38 #include <net/arp.h>
  39 #include <net/checksum.h>
  40 #include <net/dsfield.h>
  41 #include <net/inet_ecn.h>
  42 #include <net/xfrm.h>
  43
  44 #ifdef CONFIG_IPV6
  45 #include <net/ipv6.h>
  46 #include <net/ip6_fib.h>
  47 #include <net/ip6_route.h>
  48 #endif
  49
  50 /*
  51    Problems & solutions
  52    --------------------
  53
  54    1. The most important issue is detecting local dead loops.
  55    They would cause complete host lockup in transmit, which
  56    would be "resolved" by stack overflow or, if queueing is enabled,
  57    with infinite looping in net_bh.
  58
  59    We cannot track such dead loops during route installation,
  60    it is infeasible task. The most general solutions would be
  61    to keep skb->encapsulation counter (sort of local ttl),
  62    and silently drop packet when it expires. It is the best
  63    solution, but it supposes maintaing new variable in ALL
  64    skb, even if no tunneling is used.
  65
  66    Current solution: t->recursion lock breaks dead loops. It looks
  67    like dev->tbusy flag, but I preferred new variable, because
  68    the semantics is different. One day, when hard_start_xmit
  69    will be multithreaded we will have to use skb->encapsulation.
  70
  71
  72
  73    2. Networking dead loops would not kill routers, but would really
  74    kill network. IP hop limit plays role of "t->recursion" in this case,
  75    if we copy it from packet being encapsulated to upper header.
  76    It is very good solution, but it introduces two problems:
  77
  78    - Routing protocols, using packets with ttl=1 (OSPF, RIP2),
  79      do not work over tunnels.
  80    - traceroute does not work. I planned to relay ICMP from tunnel,
  81      so that this problem would be solved and traceroute output
  82      would even more informative. This idea appeared to be wrong:
  83      only Linux complies to rfc1812 now (yes, guys, Linux is the only
  84      true router now :-)), all routers (at least, in neighbourhood of mine)
  85      return only 8 bytes of payload. It is the end.
  86
  87    Hence, if we want that OSPF worked or traceroute said something reasonable,
  88    we should search for another solution.
  89
  90    One of them is to parse packet trying to detect inner encapsulation
  91    made by our node. It is difficult or even impossible, especially,
  92    taking into account fragmentation. TO be short, tt is not solution at all.
  93
  94    Current solution: The solution was UNEXPECTEDLY SIMPLE.
  95    We force DF flag on tunnels with preconfigured hop limit,
  96    that is ALL. :-) Well, it does not remove the problem completely,
  97    but exponential growth of network traffic is changed to linear
  98    (branches, that exceed pmtu are pruned) and tunnel mtu
  99    fastly degrades to value <68, where looping stops.
 100    Yes, it is not good if there exists a router in the loop,
 101    which does not force DF, even when encapsulating packets have DF set.
 102    But it is not our problem! Nobody could accuse us, we made
 103    all that we could make. Even if it is your gated who injected
 104    fatal route to network, even if it were you who configured
 105    fatal static route: you are innocent. :-)
 106
 107
 108
 109    3. Really, ipv4/ipip.c, ipv4/ip_gre.c and ipv6/sit.c contain
 110    practically identical code. It would be good to glue them
 111    together, but it is not very evident, how to make them modular.
 112    sit is integral part of IPv6, ipip and gre are naturally modular.
 113    We could extract common parts (hash table, ioctl etc)
 114    to a separate module (ip_tunnel.c).
 115
 116    Alexey Kuznetsov.
 117  */
 118
 119 static int ipgre_tunnel_init(struct net_device *dev);
 120 static void ipgre_tunnel_setup(struct net_device *dev);
 121
 122 /* Fallback tunnel: no source, no destination, no key, no options */
 123
 124 static int ipgre_fb_tunnel_init(struct net_device *dev);
 125
 126 static struct net_device *ipgre_fb_tunnel_dev;
 127
 128 /* Tunnel hash table */
 129
 130 /*
 131    4 hash tables:
 132
 133    3: (remote,local)
 134    2: (remote,*)
 135    1: (*,local)
 136    0: (*,*)
 137
 138    We require exact key match i.e. if a key is present in packet
 139    it will match only tunnel with the same key; if it is not present,
 140    it will match only keyless tunnel.
 141
 142    All keysless packets, if not matched configured keyless tunnels
 143    will match fallback tunnel.
 144  */
 145
 146 #define HASH_SIZE  16
 147 #define HASH(addr) ((addr^(addr>>4))&0xF)
 148
 149 static struct ip_tunnel *tunnels[4][HASH_SIZE];
 150
 151 #define tunnels_r_l     (tunnels[3])
 152 #define tunnels_r       (tunnels[2])
 153 #define tunnels_l       (tunnels[1])
 154 #define tunnels_wc      (tunnels[0])
 155
 156 static DEFINE_RWLOCK(ipgre_lock);
 157
 158 /* Given src, dst and key, find appropriate for input tunnel. */
 159
 160 static struct ip_tunnel * ipgre_tunnel_lookup(u32 remote, u32 local, u32 key)
 161 {
 162         unsigned h0 = HASH(remote);
 163         unsigned h1 = HASH(key);
 164         struct ip_tunnel *t;
 165
 166         for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
 167                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
 168                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 169                                 return t;
 170                 }
 171         }
 172         for (t = tunnels_r[h0^h1]; t; t = t->next) {
 173                 if (remote == t->parms.iph.daddr) {
 174                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 175                                 return t;
 176                 }
 177         }
 178         for (t = tunnels_l[h1]; t; t = t->next) {
 179                 if (local == t->parms.iph.saddr ||
 180                      (local == t->parms.iph.daddr && MULTICAST(local))) {
 181                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 182                                 return t;
 183                 }
 184         }
 185         for (t = tunnels_wc[h1]; t; t = t->next) {
 186                 if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 187                         return t;
 188         }
 189
 190         if (ipgre_fb_tunnel_dev->flags&IFF_UP)
 191                 return netdev_priv(ipgre_fb_tunnel_dev);
 192         return NULL;
 193 }
 194
 195 static struct ip_tunnel **ipgre_bucket(struct ip_tunnel *t)
 196 {
 197         u32 remote = t->parms.iph.daddr;
 198         u32 local = t->parms.iph.saddr;
 199         u32 key = t->parms.i_key;
 200         unsigned h = HASH(key);
 201         int prio = 0;
 202
 203         if (local)
 204                 prio |= 1;
 205         if (remote && !MULTICAST(remote)) {
 206                 prio |= 2;
 207                 h ^= HASH(remote);
 208         }
 209
 210         return &tunnels[prio][h];
 211 }
 212
 213 static void ipgre_tunnel_link(struct ip_tunnel *t)
 214 {
 215         struct ip_tunnel **tp = ipgre_bucket(t);
 216
 217         t->next = *tp;
 218         write_lock_bh(&ipgre_lock);
 219         *tp = t;
 220         write_unlock_bh(&ipgre_lock);
 221 }
 222
 223 static void ipgre_tunnel_unlink(struct ip_tunnel *t)
 224 {
 225         struct ip_tunnel **tp;
 226
 227         for (tp = ipgre_bucket(t); *tp; tp = &(*tp)->next) {
 228                 if (t == *tp) {
 229                         write_lock_bh(&ipgre_lock);
 230                         *tp = t->next;
 231                         write_unlock_bh(&ipgre_lock);
 232                         break;
 233                 }
 234         }
 235 }
 236
 237 static struct ip_tunnel * ipgre_tunnel_locate(struct ip_tunnel_parm *parms, int create)
 238 {
 239         u32 remote = parms->iph.daddr;
 240         u32 local = parms->iph.saddr;
 241         u32 key = parms->i_key;
 242         struct ip_tunnel *t, **tp, *nt;
 243         struct net_device *dev;
 244         unsigned h = HASH(key);
 245         int prio = 0;
 246         char name[IFNAMSIZ];
 247
 248         if (local)
 249                 prio |= 1;
 250         if (remote && !MULTICAST(remote)) {
 251                 prio |= 2;
 252                 h ^= HASH(remote);
 253         }
 254         for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
 255                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
 256                         if (key == t->parms.i_key)
 257                                 return t;
 258                 }
 259         }
 260         if (!create)
 261                 return NULL;
 262
 263         if (parms->name[0])
 264                 strlcpy(name, parms->name, IFNAMSIZ);
 265         else {
 266                 int i;
 267                 for (i=1; i<100; i++) {
 268                         sprintf(name, "gre%d", i);
 269                         if (__dev_get_by_name(name) == NULL)
 270                                 break;
 271                 }
 272                 if (i==100)
 273                         goto failed;
 274         }
 275
 276         dev = alloc_netdev(sizeof(*t), name, ipgre_tunnel_setup);
 277         if (!dev)
 278           return NULL;
 279
 280         dev->init = ipgre_tunnel_init;
 281         nt = netdev_priv(dev);
 282         nt->parms = *parms;
 283
 284         if (register_netdevice(dev) < 0) {
 285                 free_netdev(dev);
 286                 goto failed;
 287         }
 288
 289         dev_hold(dev);
 290         ipgre_tunnel_link(nt);
 291         return nt;
 292
 293 failed:
 294         return NULL;
 295 }
 296
 297 static void ipgre_tunnel_uninit(struct net_device *dev)
 298 {
 299         ipgre_tunnel_unlink(netdev_priv(dev));
 300         dev_put(dev);
 301 }
 302
 303
 304 static void ipgre_err(struct sk_buff *skb, u32 info)
 305 {
 306 #ifndef I_WISH_WORLD_WERE_PERFECT
 307
 308 /* It is not :-( All the routers (except for Linux) return only
 309    8 bytes of packet payload. It means, that precise relaying of
 310    ICMP in the real Internet is absolutely infeasible.
 311
 312    Moreover, Cisco "wise men" put GRE key to the third word
 313    in GRE header. It makes impossible maintaining even soft state for keyed
 314    GRE tunnels with enabled checksum. Tell them "thank you".
 315
 316    Well, I wonder, rfc1812 was written by Cisco employee,
 317    what the hell these idiots break standrads established
 318    by themself???
 319  */
 320
 321         struct iphdr *iph = (struct iphdr*)skb->data;
 322         u16          *p = (u16*)(skb->data+(iph->ihl<<2));
 323         int grehlen = (iph->ihl<<2) + 4;
 324         int type = skb->h.icmph->type;
 325         int code = skb->h.icmph->code;
 326         struct ip_tunnel *t;
 327         u16 flags;
 328
 329         flags = p[0];
 330         if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
 331                 if (flags&(GRE_VERSION|GRE_ROUTING))
 332                         return;
 333                 if (flags&GRE_KEY) {
 334                         grehlen += 4;
 335                         if (flags&GRE_CSUM)
 336                                 grehlen += 4;
 337                 }
 338         }
 339
 340         /* If only 8 bytes returned, keyed message will be dropped here */
 341         if (skb_headlen(skb) < grehlen)
 342                 return;
 343
 344         switch (type) {
 345         default:
 346         case ICMP_PARAMETERPROB:
 347                 return;
 348
 349         case ICMP_DEST_UNREACH:
 350                 switch (code) {
 351                 case ICMP_SR_FAILED:
 352                 case ICMP_PORT_UNREACH:
 353                         /* Impossible event. */
 354                         return;
 355                 case ICMP_FRAG_NEEDED:
 356                         /* Soft state for pmtu is maintained by IP core. */
 357                         return;
 358                 default:
 359                         /* All others are translated to HOST_UNREACH.
 360                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 361                            I believe they are just ether pollution. --ANK
 362                          */
 363                         break;
 364                 }
 365                 break;
 366         case ICMP_TIME_EXCEEDED:
 367                 if (code != ICMP_EXC_TTL)
 368                         return;
 369                 break;
 370         }
 371
 372         read_lock(&ipgre_lock);
 373         t = ipgre_tunnel_lookup(iph->daddr, iph->saddr, (flags&GRE_KEY) ? *(((u32*)p) + (grehlen>>2) - 1) : 0);
 374         if (t == NULL || t->parms.iph.daddr == 0 || MULTICAST(t->parms.iph.daddr))
 375                 goto out;
 376
 377         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 378                 goto out;
 379
 380         if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
 381                 t->err_count++;
 382         else
 383                 t->err_count = 1;
 384         t->err_time = jiffies;
 385 out:
 386         read_unlock(&ipgre_lock);
 387         return;
 388 #else
 389         struct iphdr *iph = (struct iphdr*)dp;
 390         struct iphdr *eiph;
 391         u16          *p = (u16*)(dp+(iph->ihl<<2));
 392         int type = skb->h.icmph->type;
 393         int code = skb->h.icmph->code;
 394         int rel_type = 0;
 395         int rel_code = 0;
 396         int rel_info = 0;
 397         u16 flags;
 398         int grehlen = (iph->ihl<<2) + 4;
 399         struct sk_buff *skb2;
 400         struct flowi fl;
 401         struct rtable *rt;
 402
 403         if (p[1] != htons(ETH_P_IP))
 404                 return;
 405
 406         flags = p[0];
 407         if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
 408                 if (flags&(GRE_VERSION|GRE_ROUTING))
 409                         return;
 410                 if (flags&GRE_CSUM)
 411                         grehlen += 4;
 412                 if (flags&GRE_KEY)
 413                         grehlen += 4;
 414                 if (flags&GRE_SEQ)
 415                         grehlen += 4;
 416         }
 417         if (len < grehlen + sizeof(struct iphdr))
 418                 return;
 419         eiph = (struct iphdr*)(dp + grehlen);
 420
 421         switch (type) {
 422         default:
 423                 return;
 424         case ICMP_PARAMETERPROB:
 425                 if (skb->h.icmph->un.gateway < (iph->ihl<<2))
 426                         return;
 427
 428                 /* So... This guy found something strange INSIDE encapsulated
 429                    packet. Well, he is fool, but what can we do ?
 430                  */
 431                 rel_type = ICMP_PARAMETERPROB;
 432                 rel_info = skb->h.icmph->un.gateway - grehlen;
 433                 break;
 434
 435         case ICMP_DEST_UNREACH:
 436                 switch (code) {
 437                 case ICMP_SR_FAILED:
 438                 case ICMP_PORT_UNREACH:
 439                         /* Impossible event. */
 440                         return;
 441                 case ICMP_FRAG_NEEDED:
 442                         /* And it is the only really necessary thing :-) */
 443                         rel_info = ntohs(skb->h.icmph->un.frag.mtu);
 444                         if (rel_info < grehlen+68)
 445                                 return;
 446                         rel_info -= grehlen;
 447                         /* BSD 4.2 MORE DOES NOT EXIST IN NATURE. */
 448                         if (rel_info > ntohs(eiph->tot_len))
 449                                 return;
 450                         break;
 451                 default:
 452                         /* All others are translated to HOST_UNREACH.
 453                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 454                            I believe, it is just ether pollution. --ANK
 455                          */
 456                         rel_type = ICMP_DEST_UNREACH;
 457                         rel_code = ICMP_HOST_UNREACH;
 458                         break;
 459                 }
 460                 break;
 461         case ICMP_TIME_EXCEEDED:
 462                 if (code != ICMP_EXC_TTL)
 463                         return;
 464                 break;
 465         }
 466
 467         /* Prepare fake skb to feed it to icmp_send */
 468         skb2 = skb_clone(skb, GFP_ATOMIC);
 469         if (skb2 == NULL)
 470                 return;
 471         dst_release(skb2->dst);
 472         skb2->dst = NULL;
 473         skb_pull(skb2, skb->data - (u8*)eiph);
 474         skb2->nh.raw = skb2->data;
 475
 476         /* Try to guess incoming interface */
 477         memset(&fl, 0, sizeof(fl));
 478         fl.fl4_dst = eiph->saddr;
 479         fl.fl4_tos = RT_TOS(eiph->tos);
 480         fl.proto = IPPROTO_GRE;
 481         if (ip_route_output_key(&rt, &fl)) {
 482                 kfree_skb(skb2);
 483                 return;
 484         }
 485         skb2->dev = rt->u.dst.dev;
 486
 487         /* route "incoming" packet */
 488         if (rt->rt_flags&RTCF_LOCAL) {
 489                 ip_rt_put(rt);
 490                 rt = NULL;
 491                 fl.fl4_dst = eiph->daddr;
 492                 fl.fl4_src = eiph->saddr;
 493                 fl.fl4_tos = eiph->tos;
 494                 if (ip_route_output_key(&rt, &fl) ||
 495                     rt->u.dst.dev->type != ARPHRD_IPGRE) {
 496                         ip_rt_put(rt);
 497                         kfree_skb(skb2);
 498                         return;
 499                 }
 500         } else {
 501                 ip_rt_put(rt);
 502                 if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos, skb2->dev) ||
 503                     skb2->dst->dev->type != ARPHRD_IPGRE) {
 504                         kfree_skb(skb2);
 505                         return;
 506                 }
 507         }
 508
 509         /* change mtu on this route */
 510         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
 511                 if (rel_info > dst_mtu(skb2->dst)) {
 512                         kfree_skb(skb2);
 513                         return;
 514                 }
 515                 skb2->dst->ops->update_pmtu(skb2->dst, rel_info);
 516                 rel_info = htonl(rel_info);
 517         } else if (type == ICMP_TIME_EXCEEDED) {
 518                 struct ip_tunnel *t = netdev_priv(skb2->dev);
 519                 if (t->parms.iph.ttl) {
 520                         rel_type = ICMP_DEST_UNREACH;
 521                         rel_code = ICMP_HOST_UNREACH;
 522                 }
 523         }
 524
 525         icmp_send(skb2, rel_type, rel_code, rel_info);
 526         kfree_skb(skb2);
 527 #endif
 528 }
 529
 530 static inline void ipgre_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 531 {
 532         if (INET_ECN_is_ce(iph->tos)) {
 533                 if (skb->protocol == htons(ETH_P_IP)) {
 534                         IP_ECN_set_ce(skb->nh.iph);
 535                 } else if (skb->protocol == htons(ETH_P_IPV6)) {
 536                         IP6_ECN_set_ce(skb->nh.ipv6h);
 537                 }
 538         }
 539 }
 540
 541 static inline u8
 542 ipgre_ecn_encapsulate(u8 tos, struct iphdr *old_iph, struct sk_buff *skb)
 543 {
 544         u8 inner = 0;
 545         if (skb->protocol == htons(ETH_P_IP))
 546                 inner = old_iph->tos;
 547         else if (skb->protocol == htons(ETH_P_IPV6))
 548                 inner = ipv6_get_dsfield((struct ipv6hdr *)old_iph);
 549         return INET_ECN_encapsulate(tos, inner);
 550 }
 551
 552 static int ipgre_rcv(struct sk_buff *skb)
 553 {
 554         struct iphdr *iph;
 555         u8     *h;
 556         u16    flags;
 557         u16    csum = 0;
 558         u32    key = 0;
 559         u32    seqno = 0;
 560         struct ip_tunnel *tunnel;
 561         int    offset = 4;
 562
 563         if (!pskb_may_pull(skb, 16))
 564                 goto drop_nolock;
 565
 566         iph = skb->nh.iph;
 567         h = skb->data;
 568         flags = *(u16*)h;
 569
 570         if (flags&(GRE_CSUM|GRE_KEY|GRE_ROUTING|GRE_SEQ|GRE_VERSION)) {
 571                 /* - Version must be 0.
 572                    - We do not support routing headers.
 573                  */
 574                 if (flags&(GRE_VERSION|GRE_ROUTING))
 575                         goto drop_nolock;
 576
 577                 if (flags&GRE_CSUM) {
 578                         switch (skb->ip_summed) {
 579                         case CHECKSUM_HW:
 580                                 csum = (u16)csum_fold(skb->csum);
 581                                 if (!csum)
 582                                         break;
 583                                 /* fall through */
 584                         case CHECKSUM_NONE:
 585                                 skb->csum = 0;
 586                                 csum = __skb_checksum_complete(skb);
 587                                 skb->ip_summed = CHECKSUM_HW;
 588                         }
 589                         offset += 4;
 590                 }
 591                 if (flags&GRE_KEY) {
 592                         key = *(u32*)(h + offset);
 593                         offset += 4;
 594                 }
 595                 if (flags&GRE_SEQ) {
 596                         seqno = ntohl(*(u32*)(h + offset));
 597                         offset += 4;
 598                 }
 599         }
 600
 601         read_lock(&ipgre_lock);
 602         if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) {
 603                 secpath_reset(skb);
 604
 605                 skb->protocol = *(u16*)(h + 2);
 606                 /* WCCP version 1 and 2 protocol decoding.
 607                  * - Change protocol to IP
 608                  * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
 609                  */
 610                 if (flags == 0 &&
 611                     skb->protocol == __constant_htons(ETH_P_WCCP)) {
 612                         skb->protocol = __constant_htons(ETH_P_IP);
 613                         if ((*(h + offset) & 0xF0) != 0x40)
 614                                 offset += 4;
 615                 }
 616
 617                 skb->mac.raw = skb->nh.raw;
 618                 skb->nh.raw = __pskb_pull(skb, offset);
 619                 skb_postpull_rcsum(skb, skb->h.raw, offset);
 620                 skb->pkt_type = PACKET_HOST;
 621 #ifdef CONFIG_NET_IPGRE_BROADCAST
 622                 if (MULTICAST(iph->daddr)) {
 623                         /* Looped back packet, drop it! */
 624                         if (((struct rtable*)skb->dst)->fl.iif == 0)
 625                                 goto drop;
 626                         tunnel->stat.multicast++;
 627                         skb->pkt_type = PACKET_BROADCAST;
 628                 }
 629 #endif
 630
 631                 if (((flags&GRE_CSUM) && csum) ||
 632                     (!(flags&GRE_CSUM) && tunnel->parms.i_flags&GRE_CSUM)) {
 633                         tunnel->stat.rx_crc_errors++;
 634                         tunnel->stat.rx_errors++;
 635                         goto drop;
 636                 }
 637                 if (tunnel->parms.i_flags&GRE_SEQ) {
 638                         if (!(flags&GRE_SEQ) ||
 639                             (tunnel->i_seqno && (s32)(seqno - tunnel->i_seqno) < 0)) {
 640                                 tunnel->stat.rx_fifo_errors++;
 641                                 tunnel->stat.rx_errors++;
 642                                 goto drop;
 643                         }
 644                         tunnel->i_seqno = seqno + 1;
 645                 }
 646                 tunnel->stat.rx_packets++;
 647                 tunnel->stat.rx_bytes += skb->len;
 648                 skb->dev = tunnel->dev;
 649                 dst_release(skb->dst);
 650                 skb->dst = NULL;
 651                 nf_reset(skb);
 652                 ipgre_ecn_decapsulate(iph, skb);
 653                 netif_rx(skb);
 654                 read_unlock(&ipgre_lock);
 655                 return(0);
 656         }
 657         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 658
 659 drop:
 660         read_unlock(&ipgre_lock);
 661 drop_nolock:
 662         kfree_skb(skb);
 663         return(0);
 664 }
 665
 666 static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 667 {
 668         struct ip_tunnel *tunnel = netdev_priv(dev);
 669         struct net_device_stats *stats = &tunnel->stat;
 670         struct iphdr  *old_iph = skb->nh.iph;
 671         struct iphdr  *tiph;
 672         u8     tos;
 673         u16    df;
 674         struct rtable *rt;                      /* Route to the other host */
 675         struct net_device *tdev;                        /* Device to other host */
 676         struct iphdr  *iph;                     /* Our new IP header */
 677         int    max_headroom;                    /* The extra header space needed */
 678         int    gre_hlen;
 679         u32    dst;
 680         int    mtu;
 681
 682         if (tunnel->recursion++) {
 683                 tunnel->stat.collisions++;
 684                 goto tx_error;
 685         }
 686
 687         if (dev->hard_header) {
 688                 gre_hlen = 0;
 689                 tiph = (struct iphdr*)skb->data;
 690         } else {
 691                 gre_hlen = tunnel->hlen;
 692                 tiph = &tunnel->parms.iph;
 693         }
 694
 695         if ((dst = tiph->daddr) == 0) {
 696                 /* NBMA tunnel */
 697
 698                 if (skb->dst == NULL) {
 699                         tunnel->stat.tx_fifo_errors++;
 700                         goto tx_error;
 701                 }
 702
 703                 if (skb->protocol == htons(ETH_P_IP)) {
 704                         rt = (struct rtable*)skb->dst;
 705                         if ((dst = rt->rt_gateway) == 0)
 706                                 goto tx_error_icmp;
 707                 }
 708 #ifdef CONFIG_IPV6
 709                 else if (skb->protocol == htons(ETH_P_IPV6)) {
 710                         struct in6_addr *addr6;
 711                         int addr_type;
 712                         struct neighbour *neigh = skb->dst->neighbour;
 713
 714                         if (neigh == NULL)
 715                                 goto tx_error;
 716
 717                         addr6 = (struct in6_addr*)&neigh->primary_key;
 718                         addr_type = ipv6_addr_type(addr6);
 719
 720                         if (addr_type == IPV6_ADDR_ANY) {
 721                                 addr6 = &skb->nh.ipv6h->daddr;
 722                                 addr_type = ipv6_addr_type(addr6);
 723                         }
 724
 725                         if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 726                                 goto tx_error_icmp;
 727
 728                         dst = addr6->s6_addr32[3];
 729                 }
 730 #endif
 731                 else
 732                         goto tx_error;
 733         }
 734
 735         tos = tiph->tos;
 736         if (tos&1) {
 737                 if (skb->protocol == htons(ETH_P_IP))
 738                         tos = old_iph->tos;
 739                 tos &= ~1;
 740         }
 741
 742         {
 743                 struct flowi fl = { .oif = tunnel->parms.link,
 744                                     .nl_u = { .ip4_u =
 745                                               { .daddr = dst,
 746                                                 .saddr = tiph->saddr,
 747                                                 .tos = RT_TOS(tos) } },
 748                                     .proto = IPPROTO_GRE };
 749                 if (ip_route_output_key(&rt, &fl)) {
 750                         tunnel->stat.tx_carrier_errors++;
 751                         goto tx_error;
 752                 }
 753         }
 754         tdev = rt->u.dst.dev;
 755
 756         if (tdev == dev) {
 757                 ip_rt_put(rt);
 758                 tunnel->stat.collisions++;
 759                 goto tx_error;
 760         }
 761
 762         df = tiph->frag_off;
 763         if (df)
 764                 mtu = dst_mtu(&rt->u.dst) - tunnel->hlen;
 765         else
 766                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 767
 768         if (skb->dst)
 769                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 770
 771         if (skb->protocol == htons(ETH_P_IP)) {
 772                 df |= (old_iph->frag_off&htons(IP_DF));
 773
 774                 if ((old_iph->frag_off&htons(IP_DF)) &&
 775                     mtu < ntohs(old_iph->tot_len)) {
 776                         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
 777                         ip_rt_put(rt);
 778                         goto tx_error;
 779                 }
 780         }
 781 #ifdef CONFIG_IPV6
 782         else if (skb->protocol == htons(ETH_P_IPV6)) {
 783                 struct rt6_info *rt6 = (struct rt6_info*)skb->dst;
 784
 785                 if (rt6 && mtu < dst_mtu(skb->dst) && mtu >= IPV6_MIN_MTU) {
 786                         if ((tunnel->parms.iph.daddr && !MULTICAST(tunnel->parms.iph.daddr)) ||
 787                             rt6->rt6i_dst.plen == 128) {
 788                                 rt6->rt6i_flags |= RTF_MODIFIED;
 789                                 skb->dst->metrics[RTAX_MTU-1] = mtu;
 790                         }
 791                 }
 792
 793                 if (mtu >= IPV6_MIN_MTU && mtu < skb->len - tunnel->hlen + gre_hlen) {
 794                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 795                         ip_rt_put(rt);
 796                         goto tx_error;
 797                 }
 798         }
 799 #endif
 800
 801         if (tunnel->err_count > 0) {
 802                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 803                         tunnel->err_count--;
 804
 805                         dst_link_failure(skb);
 806                 } else
 807                         tunnel->err_count = 0;
 808         }
 809
 810         max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen;
 811
 812         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 813                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 814                 if (!new_skb) {
 815                         ip_rt_put(rt);
 816                         stats->tx_dropped++;
 817                         dev_kfree_skb(skb);
 818                         tunnel->recursion--;
 819                         return 0;
 820                 }
 821                 if (skb->sk)
 822                         skb_set_owner_w(new_skb, skb->sk);
 823                 dev_kfree_skb(skb);
 824                 skb = new_skb;
 825                 old_iph = skb->nh.iph;
 826         }
 827
 828         skb->h.raw = skb->nh.raw;
 829         skb->nh.raw = skb_push(skb, gre_hlen);
 830         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 831         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
 832                               IPSKB_REROUTED);
 833         dst_release(skb->dst);
 834         skb->dst = &rt->u.dst;
 835
 836         /*
 837          *      Push down and install the IPIP header.
 838          */
 839
 840         iph                     =       skb->nh.iph;
 841         iph->version            =       4;
 842         iph->ihl                =       sizeof(struct iphdr) >> 2;
 843         iph->frag_off           =       df;
 844         iph->protocol           =       IPPROTO_GRE;
 845         iph->tos                =       ipgre_ecn_encapsulate(tos, old_iph, skb);
 846         iph->daddr              =       rt->rt_dst;
 847         iph->saddr              =       rt->rt_src;
 848
 849         if ((iph->ttl = tiph->ttl) == 0) {
 850                 if (skb->protocol == htons(ETH_P_IP))
 851                         iph->ttl = old_iph->ttl;
 852 #ifdef CONFIG_IPV6
 853                 else if (skb->protocol == htons(ETH_P_IPV6))
 854                         iph->ttl = ((struct ipv6hdr*)old_iph)->hop_limit;
 855 #endif
 856                 else
 857                         iph->ttl = dst_metric(&rt->u.dst, RTAX_HOPLIMIT);
 858         }
 859
 860         ((u16*)(iph+1))[0] = tunnel->parms.o_flags;
 861         ((u16*)(iph+1))[1] = skb->protocol;
 862
 863         if (tunnel->parms.o_flags&(GRE_KEY|GRE_CSUM|GRE_SEQ)) {
 864                 u32 *ptr = (u32*)(((u8*)iph) + tunnel->hlen - 4);
 865
 866                 if (tunnel->parms.o_flags&GRE_SEQ) {
 867                         ++tunnel->o_seqno;
 868                         *ptr = htonl(tunnel->o_seqno);
 869                         ptr--;
 870                 }
 871                 if (tunnel->parms.o_flags&GRE_KEY) {
 872                         *ptr = tunnel->parms.o_key;
 873                         ptr--;
 874                 }
 875                 if (tunnel->parms.o_flags&GRE_CSUM) {
 876                         *ptr = 0;
 877                         *(__u16*)ptr = ip_compute_csum((void*)(iph+1), skb->len - sizeof(struct iphdr));
 878                 }
 879         }
 880
 881         nf_reset(skb);
 882
 883         IPTUNNEL_XMIT();
 884         tunnel->recursion--;
 885         return 0;
 886
 887 tx_error_icmp:
 888         dst_link_failure(skb);
 889
 890 tx_error:
 891         stats->tx_errors++;
 892         dev_kfree_skb(skb);
 893         tunnel->recursion--;
 894         return 0;
 895 }
 896
 897 static int
 898 ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 899 {
 900         int err = 0;
 901         struct ip_tunnel_parm p;
 902         struct ip_tunnel *t;
 903
 904         switch (cmd) {
 905         case SIOCGETTUNNEL:
 906                 t = NULL;
 907                 if (dev == ipgre_fb_tunnel_dev) {
 908                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 909                                 err = -EFAULT;
 910                                 break;
 911                         }
 912                         t = ipgre_tunnel_locate(&p, 0);
 913                 }
 914                 if (t == NULL)
 915                         t = netdev_priv(dev);
 916                 memcpy(&p, &t->parms, sizeof(p));
 917                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 918                         err = -EFAULT;
 919                 break;
 920
 921         case SIOCADDTUNNEL:
 922         case SIOCCHGTUNNEL:
 923                 err = -EPERM;
 924                 if (!capable(CAP_NET_ADMIN))
 925                         goto done;
 926
 927                 err = -EFAULT;
 928                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 929                         goto done;
 930
 931                 err = -EINVAL;
 932                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_GRE ||
 933                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)) ||
 934                     ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING)))
 935                         goto done;
 936                 if (p.iph.ttl)
 937                         p.iph.frag_off |= htons(IP_DF);
 938
 939                 if (!(p.i_flags&GRE_KEY))
 940                         p.i_key = 0;
 941                 if (!(p.o_flags&GRE_KEY))
 942                         p.o_key = 0;
 943
 944                 t = ipgre_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 945
 946                 if (dev != ipgre_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 947                         if (t != NULL) {
 948                                 if (t->dev != dev) {
 949                                         err = -EEXIST;
 950                                         break;
 951                                 }
 952                         } else {
 953                                 unsigned nflags=0;
 954
 955                                 t = netdev_priv(dev);
 956
 957                                 if (MULTICAST(p.iph.daddr))
 958                                         nflags = IFF_BROADCAST;
 959                                 else if (p.iph.daddr)
 960                                         nflags = IFF_POINTOPOINT;
 961
 962                                 if ((dev->flags^nflags)&(IFF_POINTOPOINT|IFF_BROADCAST)) {
 963                                         err = -EINVAL;
 964                                         break;
 965                                 }
 966                                 ipgre_tunnel_unlink(t);
 967                                 t->parms.iph.saddr = p.iph.saddr;
 968                                 t->parms.iph.daddr = p.iph.daddr;
 969                                 t->parms.i_key = p.i_key;
 970                                 t->parms.o_key = p.o_key;
 971                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 972                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 973                                 ipgre_tunnel_link(t);
 974                                 netdev_state_change(dev);
 975                         }
 976                 }
 977
 978                 if (t) {
 979                         err = 0;
 980                         if (cmd == SIOCCHGTUNNEL) {
 981                                 t->parms.iph.ttl = p.iph.ttl;
 982                                 t->parms.iph.tos = p.iph.tos;
 983                                 t->parms.iph.frag_off = p.iph.frag_off;
 984                         }
 985                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 986                                 err = -EFAULT;
 987                 } else
 988                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 989                 break;
 990
 991         case SIOCDELTUNNEL:
 992                 err = -EPERM;
 993                 if (!capable(CAP_NET_ADMIN))
 994                         goto done;
 995
 996                 if (dev == ipgre_fb_tunnel_dev) {
 997                         err = -EFAULT;
 998                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 999                                 goto done;
1000                         err = -ENOENT;
1001                         if ((t = ipgre_tunnel_locate(&p, 0)) == NULL)
1002                                 goto done;
1003                         err = -EPERM;
1004                         if (t == netdev_priv(ipgre_fb_tunnel_dev))
1005                                 goto done;
1006                         dev = t->dev;
1007                 }
1008                 err = unregister_netdevice(dev);
1009                 break;
1010
1011         default:
1012                 err = -EINVAL;
1013         }
1014
1015 done:
1016         return err;
1017 }
1018
1019 static struct net_device_stats *ipgre_tunnel_get_stats(struct net_device *dev)
1020 {
1021         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
1022 }
1023
1024 static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1025 {
1026         struct ip_tunnel *tunnel = netdev_priv(dev);
1027         if (new_mtu < 68 || new_mtu > 0xFFF8 - tunnel->hlen)
1028                 return -EINVAL;
1029         dev->mtu = new_mtu;
1030         return 0;
1031 }
1032
1033 #ifdef CONFIG_NET_IPGRE_BROADCAST
1034 /* Nice toy. Unfortunately, useless in real life :-)
1035    It allows to construct virtual multiprotocol broadcast "LAN"
1036    over the Internet, provided multicast routing is tuned.
1037
1038
1039    I have no idea was this bicycle invented before me,
1040    so that I had to set ARPHRD_IPGRE to a random value.
1041    I have an impression, that Cisco could make something similar,
1042    but this feature is apparently missing in IOS<=11.2(8).
1043
1044    I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks
1045    with broadcast 224.66.66.66. If you have access to mbone, play with me :-)
1046
1047    ping -t 255 224.66.66.66
1048
1049    If nobody answers, mbone does not work.
1050
1051    ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255
1052    ip addr add 10.66.66.<somewhat>/24 dev Universe
1053    ifconfig Universe up
1054    ifconfig Universe add fe80::<Your_real_addr>/10
1055    ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96
1056    ftp 10.66.66.66
1057    ...
1058    ftp fec0:6666:6666::193.233.7.65
1059    ...
1060
1061  */
1062
1063 static int ipgre_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
1064                         void *daddr, void *saddr, unsigned len)
1065 {
1066         struct ip_tunnel *t = netdev_priv(dev);
1067         struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen);
1068         u16 *p = (u16*)(iph+1);
1069
1070         memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
1071         p[0]            = t->parms.o_flags;
1072         p[1]            = htons(type);
1073
1074         /*
1075          *      Set the source hardware address.
1076          */
1077
1078         if (saddr)
1079                 memcpy(&iph->saddr, saddr, 4);
1080
1081         if (daddr) {
1082                 memcpy(&iph->daddr, daddr, 4);
1083                 return t->hlen;
1084         }
1085         if (iph->daddr && !MULTICAST(iph->daddr))
1086                 return t->hlen;
1087
1088         return -t->hlen;
1089 }
1090
1091 static int ipgre_open(struct net_device *dev)
1092 {
1093         struct ip_tunnel *t = netdev_priv(dev);
1094
1095         if (MULTICAST(t->parms.iph.daddr)) {
1096                 struct flowi fl = { .oif = t->parms.link,
1097                                     .nl_u = { .ip4_u =
1098                                               { .daddr = t->parms.iph.daddr,
1099                                                 .saddr = t->parms.iph.saddr,
1100                                                 .tos = RT_TOS(t->parms.iph.tos) } },
1101                                     .proto = IPPROTO_GRE };
1102                 struct rtable *rt;
1103                 if (ip_route_output_key(&rt, &fl))
1104                         return -EADDRNOTAVAIL;
1105                 dev = rt->u.dst.dev;
1106                 ip_rt_put(rt);
1107                 if (__in_dev_get_rtnl(dev) == NULL)
1108                         return -EADDRNOTAVAIL;
1109                 t->mlink = dev->ifindex;
1110                 ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);
1111         }
1112         return 0;
1113 }
1114
1115 static int ipgre_close(struct net_device *dev)
1116 {
1117         struct ip_tunnel *t = netdev_priv(dev);
1118         if (MULTICAST(t->parms.iph.daddr) && t->mlink) {
1119                 struct in_device *in_dev = inetdev_by_index(t->mlink);
1120                 if (in_dev) {
1121                         ip_mc_dec_group(in_dev, t->parms.iph.daddr);
1122                         in_dev_put(in_dev);
1123                 }
1124         }
1125         return 0;
1126 }
1127
1128 #endif
1129
1130 static void ipgre_tunnel_setup(struct net_device *dev)
1131 {
1132         SET_MODULE_OWNER(dev);
1133         dev->uninit             = ipgre_tunnel_uninit;
1134         dev->destructor         = free_netdev;
1135         dev->hard_start_xmit    = ipgre_tunnel_xmit;
1136         dev->get_stats          = ipgre_tunnel_get_stats;
1137         dev->do_ioctl           = ipgre_tunnel_ioctl;
1138         dev->change_mtu         = ipgre_tunnel_change_mtu;
1139
1140         dev->type               = ARPHRD_IPGRE;
1141         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr) + 4;
1142         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr) - 4;
1143         dev->flags              = IFF_NOARP;
1144         dev->iflink             = 0;
1145         dev->addr_len           = 4;
1146 }
1147
1148 static int ipgre_tunnel_init(struct net_device *dev)
1149 {
1150         struct net_device *tdev = NULL;
1151         struct ip_tunnel *tunnel;
1152         struct iphdr *iph;
1153         int hlen = LL_MAX_HEADER;
1154         int mtu = ETH_DATA_LEN;
1155         int addend = sizeof(struct iphdr) + 4;
1156
1157         tunnel = netdev_priv(dev);
1158         iph = &tunnel->parms.iph;
1159
1160         tunnel->dev = dev;
1161         strcpy(tunnel->parms.name, dev->name);
1162
1163         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1164         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1165
1166         /* Guess output device to choose reasonable mtu and hard_header_len */
1167
1168         if (iph->daddr) {
1169                 struct flowi fl = { .oif = tunnel->parms.link,
1170                                     .nl_u = { .ip4_u =
1171                                               { .daddr = iph->daddr,
1172                                                 .saddr = iph->saddr,
1173                                                 .tos = RT_TOS(iph->tos) } },
1174                                     .proto = IPPROTO_GRE };
1175                 struct rtable *rt;
1176                 if (!ip_route_output_key(&rt, &fl)) {
1177                         tdev = rt->u.dst.dev;
1178                         ip_rt_put(rt);
1179                 }
1180
1181                 dev->flags |= IFF_POINTOPOINT;
1182
1183 #ifdef CONFIG_NET_IPGRE_BROADCAST
1184                 if (MULTICAST(iph->daddr)) {
1185                         if (!iph->saddr)
1186                                 return -EINVAL;
1187                         dev->flags = IFF_BROADCAST;
1188                         dev->hard_header = ipgre_header;
1189                         dev->open = ipgre_open;
1190                         dev->stop = ipgre_close;
1191                 }
1192 #endif
1193         }
1194
1195         if (!tdev && tunnel->parms.link)
1196                 tdev = __dev_get_by_index(tunnel->parms.link);
1197
1198         if (tdev) {
1199                 hlen = tdev->hard_header_len;
1200                 mtu = tdev->mtu;
1201         }
1202         dev->iflink = tunnel->parms.link;
1203
1204         /* Precalculate GRE options length */
1205         if (tunnel->parms.o_flags&(GRE_CSUM|GRE_KEY|GRE_SEQ)) {
1206                 if (tunnel->parms.o_flags&GRE_CSUM)
1207                         addend += 4;
1208                 if (tunnel->parms.o_flags&GRE_KEY)
1209                         addend += 4;
1210                 if (tunnel->parms.o_flags&GRE_SEQ)
1211                         addend += 4;
1212         }
1213         dev->hard_header_len = hlen + addend;
1214         dev->mtu = mtu - addend;
1215         tunnel->hlen = addend;
1216         return 0;
1217 }
1218
1219 static int __init ipgre_fb_tunnel_init(struct net_device *dev)
1220 {
1221         struct ip_tunnel *tunnel = netdev_priv(dev);
1222         struct iphdr *iph = &tunnel->parms.iph;
1223
1224         tunnel->dev = dev;
1225         strcpy(tunnel->parms.name, dev->name);
1226
1227         iph->version            = 4;
1228         iph->protocol           = IPPROTO_GRE;
1229         iph->ihl                = 5;
1230         tunnel->hlen            = sizeof(struct iphdr) + 4;
1231
1232         dev_hold(dev);
1233         tunnels_wc[0]           = tunnel;
1234         return 0;
1235 }
1236
1237
1238 static struct net_protocol ipgre_protocol = {
1239         .handler        =       ipgre_rcv,
1240         .err_handler    =       ipgre_err,
1241 };
1242
1243
1244 /*
1245  *      And now the modules code and kernel interface.
1246  */
1247
1248 static int __init ipgre_init(void)
1249 {
1250         int err;
1251
1252         printk(KERN_INFO "GRE over IPv4 tunneling driver\n");
1253
1254         if (inet_add_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) {
1255                 printk(KERN_INFO "ipgre init: can't add protocol\n");
1256                 return -EAGAIN;
1257         }
1258
1259         ipgre_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0",
1260                                            ipgre_tunnel_setup);
1261         if (!ipgre_fb_tunnel_dev) {
1262                 err = -ENOMEM;
1263                 goto err1;
1264         }
1265
1266         ipgre_fb_tunnel_dev->init = ipgre_fb_tunnel_init;
1267
1268         if ((err = register_netdev(ipgre_fb_tunnel_dev)))
1269                 goto err2;
1270 out:
1271         return err;
1272 err2:
1273         free_netdev(ipgre_fb_tunnel_dev);
1274 err1:
1275         inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
1276         goto out;
1277 }
1278
1279 static void __exit ipgre_destroy_tunnels(void)
1280 {
1281         int prio;
1282
1283         for (prio = 0; prio < 4; prio++) {
1284                 int h;
1285                 for (h = 0; h < HASH_SIZE; h++) {
1286                         struct ip_tunnel *t;
1287                         while ((t = tunnels[prio][h]) != NULL)
1288                                 unregister_netdevice(t->dev);
1289                 }
1290         }
1291 }
1292
1293 static void __exit ipgre_fini(void)
1294 {
1295         if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0)
1296                 printk(KERN_INFO "ipgre close: can't remove protocol\n");
1297
1298         rtnl_lock();
1299         ipgre_destroy_tunnels();
1300         rtnl_unlock();
1301 }
1302
1303 module_init(ipgre_init);
1304 module_exit(ipgre_fini);
1305 MODULE_LICENSE("GPL");