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/config.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
  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) ((addr^(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(u32 remote, u32 local, u32 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 ipgre_fb_tunnel_dev->priv;
 191         return NULL;
 192 }
 193
 194 static struct ip_tunnel **ipgre_bucket(struct ip_tunnel *t)
 195 {
 196         u32 remote = t->parms.iph.daddr;
 197         u32 local = t->parms.iph.saddr;
 198         u32 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         u32 remote = parms->iph.daddr;
 239         u32 local = parms->iph.saddr;
 240         u32 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 = dev->priv;
 281         nt->parms = *parms;
 282
 283         if (register_netdevice(dev) < 0) {
 284                 free_netdev(dev);
 285                 goto failed;
 286         }
 287
 288         nt = dev->priv;
 289         nt->parms = *parms;
 290
 291         dev_hold(dev);
 292         ipgre_tunnel_link(nt);
 293         return nt;
 294
 295 failed:
 296         return NULL;
 297 }
 298
 299 static void ipgre_tunnel_uninit(struct net_device *dev)
 300 {
 301         ipgre_tunnel_unlink((struct ip_tunnel*)dev->priv);
 302         dev_put(dev);
 303 }
 304
 305
 306 static void ipgre_err(struct sk_buff *skb, u32 info)
 307 {
 308 #ifndef I_WISH_WORLD_WERE_PERFECT
 309
 310 /* It is not :-( All the routers (except for Linux) return only
 311    8 bytes of packet payload. It means, that precise relaying of
 312    ICMP in the real Internet is absolutely infeasible.
 313
 314    Moreover, Cisco "wise men" put GRE key to the third word
 315    in GRE header. It makes impossible maintaining even soft state for keyed
 316    GRE tunnels with enabled checksum. Tell them "thank you".
 317
 318    Well, I wonder, rfc1812 was written by Cisco employee,
 319    what the hell these idiots break standrads established
 320    by themself???
 321  */
 322
 323         struct iphdr *iph = (struct iphdr*)skb->data;
 324         u16          *p = (u16*)(skb->data+(iph->ihl<<2));
 325         int grehlen = (iph->ihl<<2) + 4;
 326         int type = skb->h.icmph->type;
 327         int code = skb->h.icmph->code;
 328         struct ip_tunnel *t;
 329         u16 flags;
 330
 331         flags = p[0];
 332         if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
 333                 if (flags&(GRE_VERSION|GRE_ROUTING))
 334                         return;
 335                 if (flags&GRE_KEY) {
 336                         grehlen += 4;
 337                         if (flags&GRE_CSUM)
 338                                 grehlen += 4;
 339                 }
 340         }
 341
 342         /* If only 8 bytes returned, keyed message will be dropped here */
 343         if (skb_headlen(skb) < grehlen)
 344                 return;
 345
 346         switch (type) {
 347         default:
 348         case ICMP_PARAMETERPROB:
 349                 return;
 350
 351         case ICMP_DEST_UNREACH:
 352                 switch (code) {
 353                 case ICMP_SR_FAILED:
 354                 case ICMP_PORT_UNREACH:
 355                         /* Impossible event. */
 356                         return;
 357                 case ICMP_FRAG_NEEDED:
 358                         /* Soft state for pmtu is maintained by IP core. */
 359                         return;
 360                 default:
 361                         /* All others are translated to HOST_UNREACH.
 362                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 363                            I believe they are just ether pollution. --ANK
 364                          */
 365                         break;
 366                 }
 367                 break;
 368         case ICMP_TIME_EXCEEDED:
 369                 if (code != ICMP_EXC_TTL)
 370                         return;
 371                 break;
 372         }
 373
 374         read_lock(&ipgre_lock);
 375         t = ipgre_tunnel_lookup(iph->daddr, iph->saddr, (flags&GRE_KEY) ? *(((u32*)p) + (grehlen>>2) - 1) : 0);
 376         if (t == NULL || t->parms.iph.daddr == 0 || MULTICAST(t->parms.iph.daddr))
 377                 goto out;
 378
 379         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 380                 goto out;
 381
 382         if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
 383                 t->err_count++;
 384         else
 385                 t->err_count = 1;
 386         t->err_time = jiffies;
 387 out:
 388         read_unlock(&ipgre_lock);
 389         return;
 390 #else
 391         struct iphdr *iph = (struct iphdr*)dp;
 392         struct iphdr *eiph;
 393         u16          *p = (u16*)(dp+(iph->ihl<<2));
 394         int type = skb->h.icmph->type;
 395         int code = skb->h.icmph->code;
 396         int rel_type = 0;
 397         int rel_code = 0;
 398         int rel_info = 0;
 399         u16 flags;
 400         int grehlen = (iph->ihl<<2) + 4;
 401         struct sk_buff *skb2;
 402         struct flowi fl;
 403         struct rtable *rt;
 404
 405         if (p[1] != htons(ETH_P_IP))
 406                 return;
 407
 408         flags = p[0];
 409         if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
 410                 if (flags&(GRE_VERSION|GRE_ROUTING))
 411                         return;
 412                 if (flags&GRE_CSUM)
 413                         grehlen += 4;
 414                 if (flags&GRE_KEY)
 415                         grehlen += 4;
 416                 if (flags&GRE_SEQ)
 417                         grehlen += 4;
 418         }
 419         if (len < grehlen + sizeof(struct iphdr))
 420                 return;
 421         eiph = (struct iphdr*)(dp + grehlen);
 422
 423         switch (type) {
 424         default:
 425                 return;
 426         case ICMP_PARAMETERPROB:
 427                 if (skb->h.icmph->un.gateway < (iph->ihl<<2))
 428                         return;
 429
 430                 /* So... This guy found something strange INSIDE encapsulated
 431                    packet. Well, he is fool, but what can we do ?
 432                  */
 433                 rel_type = ICMP_PARAMETERPROB;
 434                 rel_info = skb->h.icmph->un.gateway - grehlen;
 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                         rel_info = ntohs(skb->h.icmph->un.frag.mtu);
 446                         if (rel_info < grehlen+68)
 447                                 return;
 448                         rel_info -= grehlen;
 449                         /* BSD 4.2 MORE DOES NOT EXIST IN NATURE. */
 450                         if (rel_info > ntohs(eiph->tot_len))
 451                                 return;
 452                         break;
 453                 default:
 454                         /* All others are translated to HOST_UNREACH.
 455                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 456                            I believe, it is just ether pollution. --ANK
 457                          */
 458                         rel_type = ICMP_DEST_UNREACH;
 459                         rel_code = ICMP_HOST_UNREACH;
 460                         break;
 461                 }
 462                 break;
 463         case ICMP_TIME_EXCEEDED:
 464                 if (code != ICMP_EXC_TTL)
 465                         return;
 466                 break;
 467         }
 468
 469         /* Prepare fake skb to feed it to icmp_send */
 470         skb2 = skb_clone(skb, GFP_ATOMIC);
 471         if (skb2 == NULL)
 472                 return;
 473         dst_release(skb2->dst);
 474         skb2->dst = NULL;
 475         skb_pull(skb2, skb->data - (u8*)eiph);
 476         skb2->nh.raw = skb2->data;
 477
 478         /* Try to guess incoming interface */
 479         memset(&fl, 0, sizeof(fl));
 480         fl.fl4_dst = eiph->saddr;
 481         fl.fl4_tos = RT_TOS(eiph->tos);
 482         fl.proto = IPPROTO_GRE;
 483         if (ip_route_output_key(&rt, &fl)) {
 484                 kfree_skb(skb2);
 485                 return;
 486         }
 487         skb2->dev = rt->u.dst.dev;
 488
 489         /* route "incoming" packet */
 490         if (rt->rt_flags&RTCF_LOCAL) {
 491                 ip_rt_put(rt);
 492                 rt = NULL;
 493                 fl.fl4_dst = eiph->daddr;
 494                 fl.fl4_src = eiph->saddr;
 495                 fl.fl4_tos = eiph->tos;
 496                 if (ip_route_output_key(&rt, &fl) ||
 497                     rt->u.dst.dev->type != ARPHRD_IPGRE) {
 498                         ip_rt_put(rt);
 499                         kfree_skb(skb2);
 500                         return;
 501                 }
 502         } else {
 503                 ip_rt_put(rt);
 504                 if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos, skb2->dev) ||
 505                     skb2->dst->dev->type != ARPHRD_IPGRE) {
 506                         kfree_skb(skb2);
 507                         return;
 508                 }
 509         }
 510
 511         /* change mtu on this route */
 512         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
 513                 if (rel_info > dst_mtu(skb2->dst)) {
 514                         kfree_skb(skb2);
 515                         return;
 516                 }
 517                 skb2->dst->ops->update_pmtu(skb2->dst, rel_info);
 518                 rel_info = htonl(rel_info);
 519         } else if (type == ICMP_TIME_EXCEEDED) {
 520                 struct ip_tunnel *t = (struct ip_tunnel*)skb2->dev->priv;
 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         u16    flags;
 559         u16    csum = 0;
 560         u32    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 = *(u16*)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                         if (skb->ip_summed == CHECKSUM_HW) {
 581                                 csum = (u16)csum_fold(skb->csum);
 582                                 if (csum)
 583                                         skb->ip_summed = CHECKSUM_NONE;
 584                         }
 585                         if (skb->ip_summed == CHECKSUM_NONE) {
 586                                 skb->csum = skb_checksum(skb, 0, skb->len, 0);
 587                                 skb->ip_summed = CHECKSUM_HW;
 588                                 csum = (u16)csum_fold(skb->csum);
 589                         }
 590                         offset += 4;
 591                 }
 592                 if (flags&GRE_KEY) {
 593                         key = *(u32*)(h + offset);
 594                         offset += 4;
 595                 }
 596                 if (flags&GRE_SEQ) {
 597                         seqno = ntohl(*(u32*)(h + offset));
 598                         offset += 4;
 599                 }
 600         }
 601
 602         read_lock(&ipgre_lock);
 603         if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) {
 604                 secpath_reset(skb);
 605
 606                 skb->protocol = *(u16*)(h + 2);
 607                 /* WCCP version 1 and 2 protocol decoding.
 608                  * - Change protocol to IP
 609                  * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
 610                  */
 611                 if (flags == 0 &&
 612                     skb->protocol == __constant_htons(ETH_P_WCCP)) {
 613                         skb->protocol = __constant_htons(ETH_P_IP);
 614                         if ((*(h + offset) & 0xF0) != 0x40)
 615                                 offset += 4;
 616                 }
 617
 618                 skb->mac.raw = skb->nh.raw;
 619                 skb->nh.raw = __pskb_pull(skb, offset);
 620                 skb_postpull_rcsum(skb, skb->mac.raw, offset);
 621                 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 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_PROT_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 = (struct ip_tunnel*)dev->priv;
 671         struct net_device_stats *stats = &tunnel->stat;
 672         struct iphdr  *old_iph = skb->nh.iph;
 673         struct iphdr  *tiph;
 674         u8     tos;
 675         u16    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         u32    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         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 = (struct ip_tunnel*)dev->priv;
 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 = (struct ip_tunnel*)dev->priv;
 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 == ipgre_fb_tunnel_dev->priv)
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*)dev->priv)->stat);
1022 }
1023
1024 static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1025 {
1026         struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
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 = (struct ip_tunnel*)dev->priv;
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 = (struct ip_tunnel*)dev->priv;
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(dev) == NULL)
1108                         return -EADDRNOTAVAIL;
1109                 t->mlink = dev->ifindex;
1110                 ip_mc_inc_group(__in_dev_get(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 = (struct ip_tunnel*)dev->priv;
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                = 1500 - 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 = 1500;
1155         int addend = sizeof(struct iphdr) + 4;
1156
1157         tunnel = (struct ip_tunnel*)dev->priv;
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 int __init ipgre_fb_tunnel_init(struct net_device *dev)
1220 {
1221         struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
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");