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/kernel.h>
  17 #include <asm/uaccess.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/in.h>
  21 #include <linux/tcp.h>
  22 #include <linux/udp.h>
  23 #include <linux/if_arp.h>
  24 #include <linux/mroute.h>
  25 #include <linux/init.h>
  26 #include <linux/in6.h>
  27 #include <linux/inetdevice.h>
  28 #include <linux/igmp.h>
  29 #include <linux/netfilter_ipv4.h>
  30 #include <linux/if_ether.h>
  31
  32 #include <net/sock.h>
  33 #include <net/ip.h>
  34 #include <net/icmp.h>
  35 #include <net/protocol.h>
  36 #include <net/ipip.h>
  37 #include <net/arp.h>
  38 #include <net/checksum.h>
  39 #include <net/dsfield.h>
  40 #include <net/inet_ecn.h>
  41 #include <net/xfrm.h>
  42
  43 #ifdef CONFIG_IPV6
  44 #include <net/ipv6.h>
  45 #include <net/ip6_fib.h>
  46 #include <net/ip6_route.h>
  47 #endif
  48
  49 /*
  50    Problems & solutions
  51    --------------------
  52
  53    1. The most important issue is detecting local dead loops.
  54    They would cause complete host lockup in transmit, which
  55    would be "resolved" by stack overflow or, if queueing is enabled,
  56    with infinite looping in net_bh.
  57
  58    We cannot track such dead loops during route installation,
  59    it is infeasible task. The most general solutions would be
  60    to keep skb->encapsulation counter (sort of local ttl),
  61    and silently drop packet when it expires. It is the best
  62    solution, but it supposes maintaing new variable in ALL
  63    skb, even if no tunneling is used.
  64
  65    Current solution: t->recursion lock breaks dead loops. It looks
  66    like dev->tbusy flag, but I preferred new variable, because
  67    the semantics is different. One day, when hard_start_xmit
  68    will be multithreaded we will have to use skb->encapsulation.
  69
  70
  71
  72    2. Networking dead loops would not kill routers, but would really
  73    kill network. IP hop limit plays role of "t->recursion" in this case,
  74    if we copy it from packet being encapsulated to upper header.
  75    It is very good solution, but it introduces two problems:
  76
  77    - Routing protocols, using packets with ttl=1 (OSPF, RIP2),
  78      do not work over tunnels.
  79    - traceroute does not work. I planned to relay ICMP from tunnel,
  80      so that this problem would be solved and traceroute output
  81      would even more informative. This idea appeared to be wrong:
  82      only Linux complies to rfc1812 now (yes, guys, Linux is the only
  83      true router now :-)), all routers (at least, in neighbourhood of mine)
  84      return only 8 bytes of payload. It is the end.
  85
  86    Hence, if we want that OSPF worked or traceroute said something reasonable,
  87    we should search for another solution.
  88
  89    One of them is to parse packet trying to detect inner encapsulation
  90    made by our node. It is difficult or even impossible, especially,
  91    taking into account fragmentation. TO be short, tt is not solution at all.
  92
  93    Current solution: The solution was UNEXPECTEDLY SIMPLE.
  94    We force DF flag on tunnels with preconfigured hop limit,
  95    that is ALL. :-) Well, it does not remove the problem completely,
  96    but exponential growth of network traffic is changed to linear
  97    (branches, that exceed pmtu are pruned) and tunnel mtu
  98    fastly degrades to value <68, where looping stops.
  99    Yes, it is not good if there exists a router in the loop,
 100    which does not force DF, even when encapsulating packets have DF set.
 101    But it is not our problem! Nobody could accuse us, we made
 102    all that we could make. Even if it is your gated who injected
 103    fatal route to network, even if it were you who configured
 104    fatal static route: you are innocent. :-)
 105
 106
 107
 108    3. Really, ipv4/ipip.c, ipv4/ip_gre.c and ipv6/sit.c contain
 109    practically identical code. It would be good to glue them
 110    together, but it is not very evident, how to make them modular.
 111    sit is integral part of IPv6, ipip and gre are naturally modular.
 112    We could extract common parts (hash table, ioctl etc)
 113    to a separate module (ip_tunnel.c).
 114
 115    Alexey Kuznetsov.
 116  */
 117
 118 static int ipgre_tunnel_init(struct net_device *dev);
 119 static void ipgre_tunnel_setup(struct net_device *dev);
 120
 121 /* Fallback tunnel: no source, no destination, no key, no options */
 122
 123 static int ipgre_fb_tunnel_init(struct net_device *dev);
 124
 125 static struct net_device *ipgre_fb_tunnel_dev;
 126
 127 /* Tunnel hash table */
 128
 129 /*
 130    4 hash tables:
 131
 132    3: (remote,local)
 133    2: (remote,*)
 134    1: (*,local)
 135    0: (*,*)
 136
 137    We require exact key match i.e. if a key is present in packet
 138    it will match only tunnel with the same key; if it is not present,
 139    it will match only keyless tunnel.
 140
 141    All keysless packets, if not matched configured keyless tunnels
 142    will match fallback tunnel.
 143  */
 144
 145 #define HASH_SIZE  16
 146 #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
 147
 148 static struct ip_tunnel *tunnels[4][HASH_SIZE];
 149
 150 #define tunnels_r_l     (tunnels[3])
 151 #define tunnels_r       (tunnels[2])
 152 #define tunnels_l       (tunnels[1])
 153 #define tunnels_wc      (tunnels[0])
 154
 155 static DEFINE_RWLOCK(ipgre_lock);
 156
 157 /* Given src, dst and key, find appropriate for input tunnel. */
 158
 159 static struct ip_tunnel * ipgre_tunnel_lookup(__be32 remote, __be32 local, __be32 key)
 160 {
 161         unsigned h0 = HASH(remote);
 162         unsigned h1 = HASH(key);
 163         struct ip_tunnel *t;
 164
 165         for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
 166                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
 167                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 168                                 return t;
 169                 }
 170         }
 171         for (t = tunnels_r[h0^h1]; t; t = t->next) {
 172                 if (remote == t->parms.iph.daddr) {
 173                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 174                                 return t;
 175                 }
 176         }
 177         for (t = tunnels_l[h1]; t; t = t->next) {
 178                 if (local == t->parms.iph.saddr ||
 179                      (local == t->parms.iph.daddr && MULTICAST(local))) {
 180                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 181                                 return t;
 182                 }
 183         }
 184         for (t = tunnels_wc[h1]; t; t = t->next) {
 185                 if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 186                         return t;
 187         }
 188
 189         if (ipgre_fb_tunnel_dev->flags&IFF_UP)
 190                 return netdev_priv(ipgre_fb_tunnel_dev);
 191         return NULL;
 192 }
 193
 194 static struct ip_tunnel **ipgre_bucket(struct ip_tunnel *t)
 195 {
 196         __be32 remote = t->parms.iph.daddr;
 197         __be32 local = t->parms.iph.saddr;
 198         __be32 key = t->parms.i_key;
 199         unsigned h = HASH(key);
 200         int prio = 0;
 201
 202         if (local)
 203                 prio |= 1;
 204         if (remote && !MULTICAST(remote)) {
 205                 prio |= 2;
 206                 h ^= HASH(remote);
 207         }
 208
 209         return &tunnels[prio][h];
 210 }
 211
 212 static void ipgre_tunnel_link(struct ip_tunnel *t)
 213 {
 214         struct ip_tunnel **tp = ipgre_bucket(t);
 215
 216         t->next = *tp;
 217         write_lock_bh(&ipgre_lock);
 218         *tp = t;
 219         write_unlock_bh(&ipgre_lock);
 220 }
 221
 222 static void ipgre_tunnel_unlink(struct ip_tunnel *t)
 223 {
 224         struct ip_tunnel **tp;
 225
 226         for (tp = ipgre_bucket(t); *tp; tp = &(*tp)->next) {
 227                 if (t == *tp) {
 228                         write_lock_bh(&ipgre_lock);
 229                         *tp = t->next;
 230                         write_unlock_bh(&ipgre_lock);
 231                         break;
 232                 }
 233         }
 234 }
 235
 236 static struct ip_tunnel * ipgre_tunnel_locate(struct ip_tunnel_parm *parms, int create)
 237 {
 238         __be32 remote = parms->iph.daddr;
 239         __be32 local = parms->iph.saddr;
 240         __be32 key = parms->i_key;
 241         struct ip_tunnel *t, **tp, *nt;
 242         struct net_device *dev;
 243         unsigned h = HASH(key);
 244         int prio = 0;
 245         char name[IFNAMSIZ];
 246
 247         if (local)
 248                 prio |= 1;
 249         if (remote && !MULTICAST(remote)) {
 250                 prio |= 2;
 251                 h ^= HASH(remote);
 252         }
 253         for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
 254                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
 255                         if (key == t->parms.i_key)
 256                                 return t;
 257                 }
 258         }
 259         if (!create)
 260                 return NULL;
 261
 262         if (parms->name[0])
 263                 strlcpy(name, parms->name, IFNAMSIZ);
 264         else {
 265                 int i;
 266                 for (i=1; i<100; i++) {
 267                         sprintf(name, "gre%d", i);
 268                         if (__dev_get_by_name(name) == NULL)
 269                                 break;
 270                 }
 271                 if (i==100)
 272                         goto failed;
 273         }
 274
 275         dev = alloc_netdev(sizeof(*t), name, ipgre_tunnel_setup);
 276         if (!dev)
 277           return NULL;
 278
 279         dev->init = ipgre_tunnel_init;
 280         nt = netdev_priv(dev);
 281         nt->parms = *parms;
 282
 283         if (register_netdevice(dev) < 0) {
 284                 free_netdev(dev);
 285                 goto failed;
 286         }
 287
 288         dev_hold(dev);
 289         ipgre_tunnel_link(nt);
 290         return nt;
 291
 292 failed:
 293         return NULL;
 294 }
 295
 296 static void ipgre_tunnel_uninit(struct net_device *dev)
 297 {
 298         ipgre_tunnel_unlink(netdev_priv(dev));
 299         dev_put(dev);
 300 }
 301
 302
 303 static void ipgre_err(struct sk_buff *skb, u32 info)
 304 {
 305 #ifndef I_WISH_WORLD_WERE_PERFECT
 306
 307 /* It is not :-( All the routers (except for Linux) return only
 308    8 bytes of packet payload. It means, that precise relaying of
 309    ICMP in the real Internet is absolutely infeasible.
 310
 311    Moreover, Cisco "wise men" put GRE key to the third word
 312    in GRE header. It makes impossible maintaining even soft state for keyed
 313    GRE tunnels with enabled checksum. Tell them "thank you".
 314
 315    Well, I wonder, rfc1812 was written by Cisco employee,
 316    what the hell these idiots break standrads established
 317    by themself???
 318  */
 319
 320         struct iphdr *iph = (struct iphdr*)skb->data;
 321         __be16       *p = (__be16*)(skb->data+(iph->ihl<<2));
 322         int grehlen = (iph->ihl<<2) + 4;
 323         int type = skb->h.icmph->type;
 324         int code = skb->h.icmph->code;
 325         struct ip_tunnel *t;
 326         __be16 flags;
 327
 328         flags = p[0];
 329         if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
 330                 if (flags&(GRE_VERSION|GRE_ROUTING))
 331                         return;
 332                 if (flags&GRE_KEY) {
 333                         grehlen += 4;
 334                         if (flags&GRE_CSUM)
 335                                 grehlen += 4;
 336                 }
 337         }
 338
 339         /* If only 8 bytes returned, keyed message will be dropped here */
 340         if (skb_headlen(skb) < grehlen)
 341                 return;
 342
 343         switch (type) {
 344         default:
 345         case ICMP_PARAMETERPROB:
 346                 return;
 347
 348         case ICMP_DEST_UNREACH:
 349                 switch (code) {
 350                 case ICMP_SR_FAILED:
 351                 case ICMP_PORT_UNREACH:
 352                         /* Impossible event. */
 353                         return;
 354                 case ICMP_FRAG_NEEDED:
 355                         /* Soft state for pmtu is maintained by IP core. */
 356                         return;
 357                 default:
 358                         /* All others are translated to HOST_UNREACH.
 359                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 360                            I believe they are just ether pollution. --ANK
 361                          */
 362                         break;
 363                 }
 364                 break;
 365         case ICMP_TIME_EXCEEDED:
 366                 if (code != ICMP_EXC_TTL)
 367                         return;
 368                 break;
 369         }
 370
 371         read_lock(&ipgre_lock);
 372         t = ipgre_tunnel_lookup(iph->daddr, iph->saddr, (flags&GRE_KEY) ? *(((__be32*)p) + (grehlen>>2) - 1) : 0);
 373         if (t == NULL || t->parms.iph.daddr == 0 || MULTICAST(t->parms.iph.daddr))
 374                 goto out;
 375
 376         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 377                 goto out;
 378
 379         if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
 380                 t->err_count++;
 381         else
 382                 t->err_count = 1;
 383         t->err_time = jiffies;
 384 out:
 385         read_unlock(&ipgre_lock);
 386         return;
 387 #else
 388         struct iphdr *iph = (struct iphdr*)dp;
 389         struct iphdr *eiph;
 390         __be16       *p = (__be16*)(dp+(iph->ihl<<2));
 391         int type = skb->h.icmph->type;
 392         int code = skb->h.icmph->code;
 393         int rel_type = 0;
 394         int rel_code = 0;
 395         __be32 rel_info = 0;
 396         __u32 n = 0;
 397         __be16 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                 n = ntohl(skb->h.icmph->un.gateway) >> 24;
 426                 if (n < (iph->ihl<<2))
 427                         return;
 428
 429                 /* So... This guy found something strange INSIDE encapsulated
 430                    packet. Well, he is fool, but what can we do ?
 431                  */
 432                 rel_type = ICMP_PARAMETERPROB;
 433                 n -= grehlen;
 434                 rel_info = htonl(n << 24);
 435                 break;
 436
 437         case ICMP_DEST_UNREACH:
 438                 switch (code) {
 439                 case ICMP_SR_FAILED:
 440                 case ICMP_PORT_UNREACH:
 441                         /* Impossible event. */
 442                         return;
 443                 case ICMP_FRAG_NEEDED:
 444                         /* And it is the only really necessary thing :-) */
 445                         n = ntohs(skb->h.icmph->un.frag.mtu);
 446                         if (n < grehlen+68)
 447                                 return;
 448                         n -= grehlen;
 449                         /* BSD 4.2 MORE DOES NOT EXIST IN NATURE. */
 450                         if (n > ntohs(eiph->tot_len))
 451                                 return;
 452                         rel_info = htonl(n);
 453                         break;
 454                 default:
 455                         /* All others are translated to HOST_UNREACH.
 456                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 457                            I believe, it is just ether pollution. --ANK
 458                          */
 459                         rel_type = ICMP_DEST_UNREACH;
 460                         rel_code = ICMP_HOST_UNREACH;
 461                         break;
 462                 }
 463                 break;
 464         case ICMP_TIME_EXCEEDED:
 465                 if (code != ICMP_EXC_TTL)
 466                         return;
 467                 break;
 468         }
 469
 470         /* Prepare fake skb to feed it to icmp_send */
 471         skb2 = skb_clone(skb, GFP_ATOMIC);
 472         if (skb2 == NULL)
 473                 return;
 474         dst_release(skb2->dst);
 475         skb2->dst = NULL;
 476         skb_pull(skb2, skb->data - (u8*)eiph);
 477         skb2->nh.raw = skb2->data;
 478
 479         /* Try to guess incoming interface */
 480         memset(&fl, 0, sizeof(fl));
 481         fl.fl4_dst = eiph->saddr;
 482         fl.fl4_tos = RT_TOS(eiph->tos);
 483         fl.proto = IPPROTO_GRE;
 484         if (ip_route_output_key(&rt, &fl)) {
 485                 kfree_skb(skb2);
 486                 return;
 487         }
 488         skb2->dev = rt->u.dst.dev;
 489
 490         /* route "incoming" packet */
 491         if (rt->rt_flags&RTCF_LOCAL) {
 492                 ip_rt_put(rt);
 493                 rt = NULL;
 494                 fl.fl4_dst = eiph->daddr;
 495                 fl.fl4_src = eiph->saddr;
 496                 fl.fl4_tos = eiph->tos;
 497                 if (ip_route_output_key(&rt, &fl) ||
 498                     rt->u.dst.dev->type != ARPHRD_IPGRE) {
 499                         ip_rt_put(rt);
 500                         kfree_skb(skb2);
 501                         return;
 502                 }
 503         } else {
 504                 ip_rt_put(rt);
 505                 if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos, skb2->dev) ||
 506                     skb2->dst->dev->type != ARPHRD_IPGRE) {
 507                         kfree_skb(skb2);
 508                         return;
 509                 }
 510         }
 511
 512         /* change mtu on this route */
 513         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
 514                 if (n > dst_mtu(skb2->dst)) {
 515                         kfree_skb(skb2);
 516                         return;
 517                 }
 518                 skb2->dst->ops->update_pmtu(skb2->dst, n);
 519         } else if (type == ICMP_TIME_EXCEEDED) {
 520                 struct ip_tunnel *t = netdev_priv(skb2->dev);
 521                 if (t->parms.iph.ttl) {
 522                         rel_type = ICMP_DEST_UNREACH;
 523                         rel_code = ICMP_HOST_UNREACH;
 524                 }
 525         }
 526
 527         icmp_send(skb2, rel_type, rel_code, rel_info);
 528         kfree_skb(skb2);
 529 #endif
 530 }
 531
 532 static inline void ipgre_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 533 {
 534         if (INET_ECN_is_ce(iph->tos)) {
 535                 if (skb->protocol == htons(ETH_P_IP)) {
 536                         IP_ECN_set_ce(skb->nh.iph);
 537                 } else if (skb->protocol == htons(ETH_P_IPV6)) {
 538                         IP6_ECN_set_ce(skb->nh.ipv6h);
 539                 }
 540         }
 541 }
 542
 543 static inline u8
 544 ipgre_ecn_encapsulate(u8 tos, struct iphdr *old_iph, struct sk_buff *skb)
 545 {
 546         u8 inner = 0;
 547         if (skb->protocol == htons(ETH_P_IP))
 548                 inner = old_iph->tos;
 549         else if (skb->protocol == htons(ETH_P_IPV6))
 550                 inner = ipv6_get_dsfield((struct ipv6hdr *)old_iph);
 551         return INET_ECN_encapsulate(tos, inner);
 552 }
 553
 554 static int ipgre_rcv(struct sk_buff *skb)
 555 {
 556         struct iphdr *iph;
 557         u8     *h;
 558         __be16    flags;
 559         __sum16   csum = 0;
 560         __be32 key = 0;
 561         u32    seqno = 0;
 562         struct ip_tunnel *tunnel;
 563         int    offset = 4;
 564
 565         if (!pskb_may_pull(skb, 16))
 566                 goto drop_nolock;
 567
 568         iph = skb->nh.iph;
 569         h = skb->data;
 570         flags = *(__be16*)h;
 571
 572         if (flags&(GRE_CSUM|GRE_KEY|GRE_ROUTING|GRE_SEQ|GRE_VERSION)) {
 573                 /* - Version must be 0.
 574                    - We do not support routing headers.
 575                  */
 576                 if (flags&(GRE_VERSION|GRE_ROUTING))
 577                         goto drop_nolock;
 578
 579                 if (flags&GRE_CSUM) {
 580                         switch (skb->ip_summed) {
 581                         case CHECKSUM_COMPLETE:
 582                                 csum = csum_fold(skb->csum);
 583                                 if (!csum)
 584                                         break;
 585                                 /* fall through */
 586                         case CHECKSUM_NONE:
 587                                 skb->csum = 0;
 588                                 csum = __skb_checksum_complete(skb);
 589                                 skb->ip_summed = CHECKSUM_COMPLETE;
 590                         }
 591                         offset += 4;
 592                 }
 593                 if (flags&GRE_KEY) {
 594                         key = *(__be32*)(h + offset);
 595                         offset += 4;
 596                 }
 597                 if (flags&GRE_SEQ) {
 598                         seqno = ntohl(*(__be32*)(h + offset));
 599                         offset += 4;
 600                 }
 601         }
 602
 603         read_lock(&ipgre_lock);
 604         if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) {
 605                 secpath_reset(skb);
 606
 607                 skb->protocol = *(__be16*)(h + 2);
 608                 /* WCCP version 1 and 2 protocol decoding.
 609                  * - Change protocol to IP
 610                  * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
 611                  */
 612                 if (flags == 0 &&
 613                     skb->protocol == htons(ETH_P_WCCP)) {
 614                         skb->protocol = htons(ETH_P_IP);
 615                         if ((*(h + offset) & 0xF0) != 0x40)
 616                                 offset += 4;
 617                 }
 618
 619                 skb->mac.raw = skb->nh.raw;
 620                 skb->nh.raw = __pskb_pull(skb, offset);
 621                 skb_postpull_rcsum(skb, skb->h.raw, offset);
 622                 skb->pkt_type = PACKET_HOST;
 623 #ifdef CONFIG_NET_IPGRE_BROADCAST
 624                 if (MULTICAST(iph->daddr)) {
 625                         /* Looped back packet, drop it! */
 626                         if (((struct rtable*)skb->dst)->fl.iif == 0)
 627                                 goto drop;
 628                         tunnel->stat.multicast++;
 629                         skb->pkt_type = PACKET_BROADCAST;
 630                 }
 631 #endif
 632
 633                 if (((flags&GRE_CSUM) && csum) ||
 634                     (!(flags&GRE_CSUM) && tunnel->parms.i_flags&GRE_CSUM)) {
 635                         tunnel->stat.rx_crc_errors++;
 636                         tunnel->stat.rx_errors++;
 637                         goto drop;
 638                 }
 639                 if (tunnel->parms.i_flags&GRE_SEQ) {
 640                         if (!(flags&GRE_SEQ) ||
 641                             (tunnel->i_seqno && (s32)(seqno - tunnel->i_seqno) < 0)) {
 642                                 tunnel->stat.rx_fifo_errors++;
 643                                 tunnel->stat.rx_errors++;
 644                                 goto drop;
 645                         }
 646                         tunnel->i_seqno = seqno + 1;
 647                 }
 648                 tunnel->stat.rx_packets++;
 649                 tunnel->stat.rx_bytes += skb->len;
 650                 skb->dev = tunnel->dev;
 651                 dst_release(skb->dst);
 652                 skb->dst = NULL;
 653                 nf_reset(skb);
 654                 ipgre_ecn_decapsulate(iph, skb);
 655                 netif_rx(skb);
 656                 read_unlock(&ipgre_lock);
 657                 return(0);
 658         }
 659         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 660
 661 drop:
 662         read_unlock(&ipgre_lock);
 663 drop_nolock:
 664         kfree_skb(skb);
 665         return(0);
 666 }
 667
 668 static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 669 {
 670         struct ip_tunnel *tunnel = netdev_priv(dev);
 671         struct net_device_stats *stats = &tunnel->stat;
 672         struct iphdr  *old_iph = skb->nh.iph;
 673         struct iphdr  *tiph;
 674         u8     tos;
 675         __be16 df;
 676         struct rtable *rt;                      /* Route to the other host */
 677         struct net_device *tdev;                        /* Device to other host */
 678         struct iphdr  *iph;                     /* Our new IP header */
 679         int    max_headroom;                    /* The extra header space needed */
 680         int    gre_hlen;
 681         __be32 dst;
 682         int    mtu;
 683
 684         if (tunnel->recursion++) {
 685                 tunnel->stat.collisions++;
 686                 goto tx_error;
 687         }
 688
 689         if (dev->hard_header) {
 690                 gre_hlen = 0;
 691                 tiph = (struct iphdr*)skb->data;
 692         } else {
 693                 gre_hlen = tunnel->hlen;
 694                 tiph = &tunnel->parms.iph;
 695         }
 696
 697         if ((dst = tiph->daddr) == 0) {
 698                 /* NBMA tunnel */
 699
 700                 if (skb->dst == NULL) {
 701                         tunnel->stat.tx_fifo_errors++;
 702                         goto tx_error;
 703                 }
 704
 705                 if (skb->protocol == htons(ETH_P_IP)) {
 706                         rt = (struct rtable*)skb->dst;
 707                         if ((dst = rt->rt_gateway) == 0)
 708                                 goto tx_error_icmp;
 709                 }
 710 #ifdef CONFIG_IPV6
 711                 else if (skb->protocol == htons(ETH_P_IPV6)) {
 712                         struct in6_addr *addr6;
 713                         int addr_type;
 714                         struct neighbour *neigh = skb->dst->neighbour;
 715
 716                         if (neigh == NULL)
 717                                 goto tx_error;
 718
 719                         addr6 = (struct in6_addr*)&neigh->primary_key;
 720                         addr_type = ipv6_addr_type(addr6);
 721
 722                         if (addr_type == IPV6_ADDR_ANY) {
 723                                 addr6 = &skb->nh.ipv6h->daddr;
 724                                 addr_type = ipv6_addr_type(addr6);
 725                         }
 726
 727                         if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 728                                 goto tx_error_icmp;
 729
 730                         dst = addr6->s6_addr32[3];
 731                 }
 732 #endif
 733                 else
 734                         goto tx_error;
 735         }
 736
 737         tos = tiph->tos;
 738         if (tos&1) {
 739                 if (skb->protocol == htons(ETH_P_IP))
 740                         tos = old_iph->tos;
 741                 tos &= ~1;
 742         }
 743
 744         {
 745                 struct flowi fl = { .oif = tunnel->parms.link,
 746                                     .nl_u = { .ip4_u =
 747                                               { .daddr = dst,
 748                                                 .saddr = tiph->saddr,
 749                                                 .tos = RT_TOS(tos) } },
 750                                     .proto = IPPROTO_GRE };
 751                 if (ip_route_output_key(&rt, &fl)) {
 752                         tunnel->stat.tx_carrier_errors++;
 753                         goto tx_error;
 754                 }
 755         }
 756         tdev = rt->u.dst.dev;
 757
 758         if (tdev == dev) {
 759                 ip_rt_put(rt);
 760                 tunnel->stat.collisions++;
 761                 goto tx_error;
 762         }
 763
 764         df = tiph->frag_off;
 765         if (df)
 766                 mtu = dst_mtu(&rt->u.dst) - tunnel->hlen;
 767         else
 768                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 769
 770         if (skb->dst)
 771                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 772
 773         if (skb->protocol == htons(ETH_P_IP)) {
 774                 df |= (old_iph->frag_off&htons(IP_DF));
 775
 776                 if ((old_iph->frag_off&htons(IP_DF)) &&
 777                     mtu < ntohs(old_iph->tot_len)) {
 778                         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
 779                         ip_rt_put(rt);
 780                         goto tx_error;
 781                 }
 782         }
 783 #ifdef CONFIG_IPV6
 784         else if (skb->protocol == htons(ETH_P_IPV6)) {
 785                 struct rt6_info *rt6 = (struct rt6_info*)skb->dst;
 786
 787                 if (rt6 && mtu < dst_mtu(skb->dst) && mtu >= IPV6_MIN_MTU) {
 788                         if ((tunnel->parms.iph.daddr && !MULTICAST(tunnel->parms.iph.daddr)) ||
 789                             rt6->rt6i_dst.plen == 128) {
 790                                 rt6->rt6i_flags |= RTF_MODIFIED;
 791                                 skb->dst->metrics[RTAX_MTU-1] = mtu;
 792                         }
 793                 }
 794
 795                 if (mtu >= IPV6_MIN_MTU && mtu < skb->len - tunnel->hlen + gre_hlen) {
 796                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 797                         ip_rt_put(rt);
 798                         goto tx_error;
 799                 }
 800         }
 801 #endif
 802
 803         if (tunnel->err_count > 0) {
 804                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 805                         tunnel->err_count--;
 806
 807                         dst_link_failure(skb);
 808                 } else
 809                         tunnel->err_count = 0;
 810         }
 811
 812         max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen;
 813
 814         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 815                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 816                 if (!new_skb) {
 817                         ip_rt_put(rt);
 818                         stats->tx_dropped++;
 819                         dev_kfree_skb(skb);
 820                         tunnel->recursion--;
 821                         return 0;
 822                 }
 823                 if (skb->sk)
 824                         skb_set_owner_w(new_skb, skb->sk);
 825                 dev_kfree_skb(skb);
 826                 skb = new_skb;
 827                 old_iph = skb->nh.iph;
 828         }
 829
 830         skb->h.raw = skb->nh.raw;
 831         skb->nh.raw = skb_push(skb, gre_hlen);
 832         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 833         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
 834                               IPSKB_REROUTED);
 835         dst_release(skb->dst);
 836         skb->dst = &rt->u.dst;
 837
 838         /*
 839          *      Push down and install the IPIP header.
 840          */
 841
 842         iph                     =       skb->nh.iph;
 843         iph->version            =       4;
 844         iph->ihl                =       sizeof(struct iphdr) >> 2;
 845         iph->frag_off           =       df;
 846         iph->protocol           =       IPPROTO_GRE;
 847         iph->tos                =       ipgre_ecn_encapsulate(tos, old_iph, skb);
 848         iph->daddr              =       rt->rt_dst;
 849         iph->saddr              =       rt->rt_src;
 850
 851         if ((iph->ttl = tiph->ttl) == 0) {
 852                 if (skb->protocol == htons(ETH_P_IP))
 853                         iph->ttl = old_iph->ttl;
 854 #ifdef CONFIG_IPV6
 855                 else if (skb->protocol == htons(ETH_P_IPV6))
 856                         iph->ttl = ((struct ipv6hdr*)old_iph)->hop_limit;
 857 #endif
 858                 else
 859                         iph->ttl = dst_metric(&rt->u.dst, RTAX_HOPLIMIT);
 860         }
 861
 862         ((__be16*)(iph+1))[0] = tunnel->parms.o_flags;
 863         ((__be16*)(iph+1))[1] = skb->protocol;
 864
 865         if (tunnel->parms.o_flags&(GRE_KEY|GRE_CSUM|GRE_SEQ)) {
 866                 __be32 *ptr = (__be32*)(((u8*)iph) + tunnel->hlen - 4);
 867
 868                 if (tunnel->parms.o_flags&GRE_SEQ) {
 869                         ++tunnel->o_seqno;
 870                         *ptr = htonl(tunnel->o_seqno);
 871                         ptr--;
 872                 }
 873                 if (tunnel->parms.o_flags&GRE_KEY) {
 874                         *ptr = tunnel->parms.o_key;
 875                         ptr--;
 876                 }
 877                 if (tunnel->parms.o_flags&GRE_CSUM) {
 878                         *ptr = 0;
 879                         *(__sum16*)ptr = ip_compute_csum((void*)(iph+1), skb->len - sizeof(struct iphdr));
 880                 }
 881         }
 882
 883         nf_reset(skb);
 884
 885         IPTUNNEL_XMIT();
 886         tunnel->recursion--;
 887         return 0;
 888
 889 tx_error_icmp:
 890         dst_link_failure(skb);
 891
 892 tx_error:
 893         stats->tx_errors++;
 894         dev_kfree_skb(skb);
 895         tunnel->recursion--;
 896         return 0;
 897 }
 898
 899 static int
 900 ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 901 {
 902         int err = 0;
 903         struct ip_tunnel_parm p;
 904         struct ip_tunnel *t;
 905
 906         switch (cmd) {
 907         case SIOCGETTUNNEL:
 908                 t = NULL;
 909                 if (dev == ipgre_fb_tunnel_dev) {
 910                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 911                                 err = -EFAULT;
 912                                 break;
 913                         }
 914                         t = ipgre_tunnel_locate(&p, 0);
 915                 }
 916                 if (t == NULL)
 917                         t = netdev_priv(dev);
 918                 memcpy(&p, &t->parms, sizeof(p));
 919                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 920                         err = -EFAULT;
 921                 break;
 922
 923         case SIOCADDTUNNEL:
 924         case SIOCCHGTUNNEL:
 925                 err = -EPERM;
 926                 if (!capable(CAP_NET_ADMIN))
 927                         goto done;
 928
 929                 err = -EFAULT;
 930                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 931                         goto done;
 932
 933                 err = -EINVAL;
 934                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_GRE ||
 935                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)) ||
 936                     ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING)))
 937                         goto done;
 938                 if (p.iph.ttl)
 939                         p.iph.frag_off |= htons(IP_DF);
 940
 941                 if (!(p.i_flags&GRE_KEY))
 942                         p.i_key = 0;
 943                 if (!(p.o_flags&GRE_KEY))
 944                         p.o_key = 0;
 945
 946                 t = ipgre_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 947
 948                 if (dev != ipgre_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 949                         if (t != NULL) {
 950                                 if (t->dev != dev) {
 951                                         err = -EEXIST;
 952                                         break;
 953                                 }
 954                         } else {
 955                                 unsigned nflags=0;
 956
 957                                 t = netdev_priv(dev);
 958
 959                                 if (MULTICAST(p.iph.daddr))
 960                                         nflags = IFF_BROADCAST;
 961                                 else if (p.iph.daddr)
 962                                         nflags = IFF_POINTOPOINT;
 963
 964                                 if ((dev->flags^nflags)&(IFF_POINTOPOINT|IFF_BROADCAST)) {
 965                                         err = -EINVAL;
 966                                         break;
 967                                 }
 968                                 ipgre_tunnel_unlink(t);
 969                                 t->parms.iph.saddr = p.iph.saddr;
 970                                 t->parms.iph.daddr = p.iph.daddr;
 971                                 t->parms.i_key = p.i_key;
 972                                 t->parms.o_key = p.o_key;
 973                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 974                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 975                                 ipgre_tunnel_link(t);
 976                                 netdev_state_change(dev);
 977                         }
 978                 }
 979
 980                 if (t) {
 981                         err = 0;
 982                         if (cmd == SIOCCHGTUNNEL) {
 983                                 t->parms.iph.ttl = p.iph.ttl;
 984                                 t->parms.iph.tos = p.iph.tos;
 985                                 t->parms.iph.frag_off = p.iph.frag_off;
 986                         }
 987                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 988                                 err = -EFAULT;
 989                 } else
 990                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 991                 break;
 992
 993         case SIOCDELTUNNEL:
 994                 err = -EPERM;
 995                 if (!capable(CAP_NET_ADMIN))
 996                         goto done;
 997
 998                 if (dev == ipgre_fb_tunnel_dev) {
 999                         err = -EFAULT;
1000                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
1001                                 goto done;
1002                         err = -ENOENT;
1003                         if ((t = ipgre_tunnel_locate(&p, 0)) == NULL)
1004                                 goto done;
1005                         err = -EPERM;
1006                         if (t == netdev_priv(ipgre_fb_tunnel_dev))
1007                                 goto done;
1008                         dev = t->dev;
1009                 }
1010                 unregister_netdevice(dev);
1011                 err = 0;
1012                 break;
1013
1014         default:
1015                 err = -EINVAL;
1016         }
1017
1018 done:
1019         return err;
1020 }
1021
1022 static struct net_device_stats *ipgre_tunnel_get_stats(struct net_device *dev)
1023 {
1024         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
1025 }
1026
1027 static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1028 {
1029         struct ip_tunnel *tunnel = netdev_priv(dev);
1030         if (new_mtu < 68 || new_mtu > 0xFFF8 - tunnel->hlen)
1031                 return -EINVAL;
1032         dev->mtu = new_mtu;
1033         return 0;
1034 }
1035
1036 #ifdef CONFIG_NET_IPGRE_BROADCAST
1037 /* Nice toy. Unfortunately, useless in real life :-)
1038    It allows to construct virtual multiprotocol broadcast "LAN"
1039    over the Internet, provided multicast routing is tuned.
1040
1041
1042    I have no idea was this bicycle invented before me,
1043    so that I had to set ARPHRD_IPGRE to a random value.
1044    I have an impression, that Cisco could make something similar,
1045    but this feature is apparently missing in IOS<=11.2(8).
1046
1047    I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks
1048    with broadcast 224.66.66.66. If you have access to mbone, play with me :-)
1049
1050    ping -t 255 224.66.66.66
1051
1052    If nobody answers, mbone does not work.
1053
1054    ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255
1055    ip addr add 10.66.66.<somewhat>/24 dev Universe
1056    ifconfig Universe up
1057    ifconfig Universe add fe80::<Your_real_addr>/10
1058    ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96
1059    ftp 10.66.66.66
1060    ...
1061    ftp fec0:6666:6666::193.233.7.65
1062    ...
1063
1064  */
1065
1066 static int ipgre_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
1067                         void *daddr, void *saddr, unsigned len)
1068 {
1069         struct ip_tunnel *t = netdev_priv(dev);
1070         struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen);
1071         __be16 *p = (__be16*)(iph+1);
1072
1073         memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
1074         p[0]            = t->parms.o_flags;
1075         p[1]            = htons(type);
1076
1077         /*
1078          *      Set the source hardware address.
1079          */
1080
1081         if (saddr)
1082                 memcpy(&iph->saddr, saddr, 4);
1083
1084         if (daddr) {
1085                 memcpy(&iph->daddr, daddr, 4);
1086                 return t->hlen;
1087         }
1088         if (iph->daddr && !MULTICAST(iph->daddr))
1089                 return t->hlen;
1090
1091         return -t->hlen;
1092 }
1093
1094 static int ipgre_open(struct net_device *dev)
1095 {
1096         struct ip_tunnel *t = netdev_priv(dev);
1097
1098         if (MULTICAST(t->parms.iph.daddr)) {
1099                 struct flowi fl = { .oif = t->parms.link,
1100                                     .nl_u = { .ip4_u =
1101                                               { .daddr = t->parms.iph.daddr,
1102                                                 .saddr = t->parms.iph.saddr,
1103                                                 .tos = RT_TOS(t->parms.iph.tos) } },
1104                                     .proto = IPPROTO_GRE };
1105                 struct rtable *rt;
1106                 if (ip_route_output_key(&rt, &fl))
1107                         return -EADDRNOTAVAIL;
1108                 dev = rt->u.dst.dev;
1109                 ip_rt_put(rt);
1110                 if (__in_dev_get_rtnl(dev) == NULL)
1111                         return -EADDRNOTAVAIL;
1112                 t->mlink = dev->ifindex;
1113                 ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);
1114         }
1115         return 0;
1116 }
1117
1118 static int ipgre_close(struct net_device *dev)
1119 {
1120         struct ip_tunnel *t = netdev_priv(dev);
1121         if (MULTICAST(t->parms.iph.daddr) && t->mlink) {
1122                 struct in_device *in_dev = inetdev_by_index(t->mlink);
1123                 if (in_dev) {
1124                         ip_mc_dec_group(in_dev, t->parms.iph.daddr);
1125                         in_dev_put(in_dev);
1126                 }
1127         }
1128         return 0;
1129 }
1130
1131 #endif
1132
1133 static void ipgre_tunnel_setup(struct net_device *dev)
1134 {
1135         SET_MODULE_OWNER(dev);
1136         dev->uninit             = ipgre_tunnel_uninit;
1137         dev->destructor         = free_netdev;
1138         dev->hard_start_xmit    = ipgre_tunnel_xmit;
1139         dev->get_stats          = ipgre_tunnel_get_stats;
1140         dev->do_ioctl           = ipgre_tunnel_ioctl;
1141         dev->change_mtu         = ipgre_tunnel_change_mtu;
1142
1143         dev->type               = ARPHRD_IPGRE;
1144         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr) + 4;
1145         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr) - 4;
1146         dev->flags              = IFF_NOARP;
1147         dev->iflink             = 0;
1148         dev->addr_len           = 4;
1149 }
1150
1151 static int ipgre_tunnel_init(struct net_device *dev)
1152 {
1153         struct net_device *tdev = NULL;
1154         struct ip_tunnel *tunnel;
1155         struct iphdr *iph;
1156         int hlen = LL_MAX_HEADER;
1157         int mtu = ETH_DATA_LEN;
1158         int addend = sizeof(struct iphdr) + 4;
1159
1160         tunnel = netdev_priv(dev);
1161         iph = &tunnel->parms.iph;
1162
1163         tunnel->dev = dev;
1164         strcpy(tunnel->parms.name, dev->name);
1165
1166         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1167         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1168
1169         /* Guess output device to choose reasonable mtu and hard_header_len */
1170
1171         if (iph->daddr) {
1172                 struct flowi fl = { .oif = tunnel->parms.link,
1173                                     .nl_u = { .ip4_u =
1174                                               { .daddr = iph->daddr,
1175                                                 .saddr = iph->saddr,
1176                                                 .tos = RT_TOS(iph->tos) } },
1177                                     .proto = IPPROTO_GRE };
1178                 struct rtable *rt;
1179                 if (!ip_route_output_key(&rt, &fl)) {
1180                         tdev = rt->u.dst.dev;
1181                         ip_rt_put(rt);
1182                 }
1183
1184                 dev->flags |= IFF_POINTOPOINT;
1185
1186 #ifdef CONFIG_NET_IPGRE_BROADCAST
1187                 if (MULTICAST(iph->daddr)) {
1188                         if (!iph->saddr)
1189                                 return -EINVAL;
1190                         dev->flags = IFF_BROADCAST;
1191                         dev->hard_header = ipgre_header;
1192                         dev->open = ipgre_open;
1193                         dev->stop = ipgre_close;
1194                 }
1195 #endif
1196         }
1197
1198         if (!tdev && tunnel->parms.link)
1199                 tdev = __dev_get_by_index(tunnel->parms.link);
1200
1201         if (tdev) {
1202                 hlen = tdev->hard_header_len;
1203                 mtu = tdev->mtu;
1204         }
1205         dev->iflink = tunnel->parms.link;
1206
1207         /* Precalculate GRE options length */
1208         if (tunnel->parms.o_flags&(GRE_CSUM|GRE_KEY|GRE_SEQ)) {
1209                 if (tunnel->parms.o_flags&GRE_CSUM)
1210                         addend += 4;
1211                 if (tunnel->parms.o_flags&GRE_KEY)
1212                         addend += 4;
1213                 if (tunnel->parms.o_flags&GRE_SEQ)
1214                         addend += 4;
1215         }
1216         dev->hard_header_len = hlen + addend;
1217         dev->mtu = mtu - addend;
1218         tunnel->hlen = addend;
1219         return 0;
1220 }
1221
1222 static int __init ipgre_fb_tunnel_init(struct net_device *dev)
1223 {
1224         struct ip_tunnel *tunnel = netdev_priv(dev);
1225         struct iphdr *iph = &tunnel->parms.iph;
1226
1227         tunnel->dev = dev;
1228         strcpy(tunnel->parms.name, dev->name);
1229
1230         iph->version            = 4;
1231         iph->protocol           = IPPROTO_GRE;
1232         iph->ihl                = 5;
1233         tunnel->hlen            = sizeof(struct iphdr) + 4;
1234
1235         dev_hold(dev);
1236         tunnels_wc[0]           = tunnel;
1237         return 0;
1238 }
1239
1240
1241 static struct net_protocol ipgre_protocol = {
1242         .handler        =       ipgre_rcv,
1243         .err_handler    =       ipgre_err,
1244 };
1245
1246
1247 /*
1248  *      And now the modules code and kernel interface.
1249  */
1250
1251 static int __init ipgre_init(void)
1252 {
1253         int err;
1254
1255         printk(KERN_INFO "GRE over IPv4 tunneling driver\n");
1256
1257         if (inet_add_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) {
1258                 printk(KERN_INFO "ipgre init: can't add protocol\n");
1259                 return -EAGAIN;
1260         }
1261
1262         ipgre_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0",
1263                                            ipgre_tunnel_setup);
1264         if (!ipgre_fb_tunnel_dev) {
1265                 err = -ENOMEM;
1266                 goto err1;
1267         }
1268
1269         ipgre_fb_tunnel_dev->init = ipgre_fb_tunnel_init;
1270
1271         if ((err = register_netdev(ipgre_fb_tunnel_dev)))
1272                 goto err2;
1273 out:
1274         return err;
1275 err2:
1276         free_netdev(ipgre_fb_tunnel_dev);
1277 err1:
1278         inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
1279         goto out;
1280 }
1281
1282 static void __exit ipgre_destroy_tunnels(void)
1283 {
1284         int prio;
1285
1286         for (prio = 0; prio < 4; prio++) {
1287                 int h;
1288                 for (h = 0; h < HASH_SIZE; h++) {
1289                         struct ip_tunnel *t;
1290                         while ((t = tunnels[prio][h]) != NULL)
1291                                 unregister_netdevice(t->dev);
1292                 }
1293         }
1294 }
1295
1296 static void __exit ipgre_fini(void)
1297 {
1298         if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0)
1299                 printk(KERN_INFO "ipgre close: can't remove protocol\n");
1300
1301         rtnl_lock();
1302         ipgre_destroy_tunnels();
1303         rtnl_unlock();
1304 }
1305
1306 module_init(ipgre_init);
1307 module_exit(ipgre_fini);
1308 MODULE_LICENSE("GPL");