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/inet_ecn.h>
  40 #include <net/xfrm.h>
  41
  42 #ifdef CONFIG_IPV6
  43 #include <net/ipv6.h>
  44 #include <net/ip6_fib.h>
  45 #include <net/ip6_route.h>
  46 #endif
  47
  48 /*
  49    Problems & solutions
  50    --------------------
  51
  52    1. The most important issue is detecting local dead loops.
  53    They would cause complete host lockup in transmit, which
  54    would be "resolved" by stack overflow or, if queueing is enabled,
  55    with infinite looping in net_bh.
  56
  57    We cannot track such dead loops during route installation,
  58    it is infeasible task. The most general solutions would be
  59    to keep skb->encapsulation counter (sort of local ttl),
  60    and silently drop packet when it expires. It is the best
  61    solution, but it supposes maintaing new variable in ALL
  62    skb, even if no tunneling is used.
  63
  64    Current solution: t->recursion lock breaks dead loops. It looks
  65    like dev->tbusy flag, but I preferred new variable, because
  66    the semantics is different. One day, when hard_start_xmit
  67    will be multithreaded we will have to use skb->encapsulation.
  68
  69
  70
  71    2. Networking dead loops would not kill routers, but would really
  72    kill network. IP hop limit plays role of "t->recursion" in this case,
  73    if we copy it from packet being encapsulated to upper header.
  74    It is very good solution, but it introduces two problems:
  75
  76    - Routing protocols, using packets with ttl=1 (OSPF, RIP2),
  77      do not work over tunnels.
  78    - traceroute does not work. I planned to relay ICMP from tunnel,
  79      so that this problem would be solved and traceroute output
  80      would even more informative. This idea appeared to be wrong:
  81      only Linux complies to rfc1812 now (yes, guys, Linux is the only
  82      true router now :-)), all routers (at least, in neighbourhood of mine)
  83      return only 8 bytes of payload. It is the end.
  84
  85    Hence, if we want that OSPF worked or traceroute said something reasonable,
  86    we should search for another solution.
  87
  88    One of them is to parse packet trying to detect inner encapsulation
  89    made by our node. It is difficult or even impossible, especially,
  90    taking into account fragmentation. TO be short, tt is not solution at all.
  91
  92    Current solution: The solution was UNEXPECTEDLY SIMPLE.
  93    We force DF flag on tunnels with preconfigured hop limit,
  94    that is ALL. :-) Well, it does not remove the problem completely,
  95    but exponential growth of network traffic is changed to linear
  96    (branches, that exceed pmtu are pruned) and tunnel mtu
  97    fastly degrades to value <68, where looping stops.
  98    Yes, it is not good if there exists a router in the loop,
  99    which does not force DF, even when encapsulating packets have DF set.
 100    But it is not our problem! Nobody could accuse us, we made
 101    all that we could make. Even if it is your gated who injected
 102    fatal route to network, even if it were you who configured
 103    fatal static route: you are innocent. :-)
 104
 105
 106
 107    3. Really, ipv4/ipip.c, ipv4/ip_gre.c and ipv6/sit.c contain
 108    practically identical code. It would be good to glue them
 109    together, but it is not very evident, how to make them modular.
 110    sit is integral part of IPv6, ipip and gre are naturally modular.
 111    We could extract common parts (hash table, ioctl etc)
 112    to a separate module (ip_tunnel.c).
 113
 114    Alexey Kuznetsov.
 115  */
 116
 117 static int ipgre_tunnel_init(struct net_device *dev);
 118 static void ipgre_tunnel_setup(struct net_device *dev);
 119
 120 /* Fallback tunnel: no source, no destination, no key, no options */
 121
 122 static int ipgre_fb_tunnel_init(struct net_device *dev);
 123
 124 static struct net_device *ipgre_fb_tunnel_dev;
 125
 126 /* Tunnel hash table */
 127
 128 /*
 129    4 hash tables:
 130
 131    3: (remote,local)
 132    2: (remote,*)
 133    1: (*,local)
 134    0: (*,*)
 135
 136    We require exact key match i.e. if a key is present in packet
 137    it will match only tunnel with the same key; if it is not present,
 138    it will match only keyless tunnel.
 139
 140    All keysless packets, if not matched configured keyless tunnels
 141    will match fallback tunnel.
 142  */
 143
 144 #define HASH_SIZE  16
 145 #define HASH(addr) ((addr^(addr>>4))&0xF)
 146
 147 static struct ip_tunnel *tunnels[4][HASH_SIZE];
 148
 149 #define tunnels_r_l     (tunnels[3])
 150 #define tunnels_r       (tunnels[2])
 151 #define tunnels_l       (tunnels[1])
 152 #define tunnels_wc      (tunnels[0])
 153
 154 static rwlock_t ipgre_lock = RW_LOCK_UNLOCKED;
 155
 156 /* Given src, dst and key, find appropriate for input tunnel. */
 157
 158 static struct ip_tunnel * ipgre_tunnel_lookup(u32 remote, u32 local, u32 key)
 159 {
 160         unsigned h0 = HASH(remote);
 161         unsigned h1 = HASH(key);
 162         struct ip_tunnel *t;
 163
 164         for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
 165                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
 166                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 167                                 return t;
 168                 }
 169         }
 170         for (t = tunnels_r[h0^h1]; t; t = t->next) {
 171                 if (remote == t->parms.iph.daddr) {
 172                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 173                                 return t;
 174                 }
 175         }
 176         for (t = tunnels_l[h1]; t; t = t->next) {
 177                 if (local == t->parms.iph.saddr ||
 178                      (local == t->parms.iph.daddr && MULTICAST(local))) {
 179                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 180                                 return t;
 181                 }
 182         }
 183         for (t = tunnels_wc[h1]; t; t = t->next) {
 184                 if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 185                         return t;
 186         }
 187
 188         if (ipgre_fb_tunnel_dev->flags&IFF_UP)
 189                 return ipgre_fb_tunnel_dev->priv;
 190         return NULL;
 191 }
 192
 193 static struct ip_tunnel **ipgre_bucket(struct ip_tunnel *t)
 194 {
 195         u32 remote = t->parms.iph.daddr;
 196         u32 local = t->parms.iph.saddr;
 197         u32 key = t->parms.i_key;
 198         unsigned h = HASH(key);
 199         int prio = 0;
 200
 201         if (local)
 202                 prio |= 1;
 203         if (remote && !MULTICAST(remote)) {
 204                 prio |= 2;
 205                 h ^= HASH(remote);
 206         }
 207
 208         return &tunnels[prio][h];
 209 }
 210
 211 static void ipgre_tunnel_link(struct ip_tunnel *t)
 212 {
 213         struct ip_tunnel **tp = ipgre_bucket(t);
 214
 215         t->next = *tp;
 216         write_lock_bh(&ipgre_lock);
 217         *tp = t;
 218         write_unlock_bh(&ipgre_lock);
 219 }
 220
 221 static void ipgre_tunnel_unlink(struct ip_tunnel *t)
 222 {
 223         struct ip_tunnel **tp;
 224
 225         for (tp = ipgre_bucket(t); *tp; tp = &(*tp)->next) {
 226                 if (t == *tp) {
 227                         write_lock_bh(&ipgre_lock);
 228                         *tp = t->next;
 229                         write_unlock_bh(&ipgre_lock);
 230                         break;
 231                 }
 232         }
 233 }
 234
 235 static struct ip_tunnel * ipgre_tunnel_locate(struct ip_tunnel_parm *parms, int create)
 236 {
 237         u32 remote = parms->iph.daddr;
 238         u32 local = parms->iph.saddr;
 239         u32 key = parms->i_key;
 240         struct ip_tunnel *t, **tp, *nt;
 241         struct net_device *dev;
 242         unsigned h = HASH(key);
 243         int prio = 0;
 244         char name[IFNAMSIZ];
 245
 246         if (local)
 247                 prio |= 1;
 248         if (remote && !MULTICAST(remote)) {
 249                 prio |= 2;
 250                 h ^= HASH(remote);
 251         }
 252         for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
 253                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
 254                         if (key == t->parms.i_key)
 255                                 return t;
 256                 }
 257         }
 258         if (!create)
 259                 return NULL;
 260
 261         if (parms->name[0])
 262                 strlcpy(name, parms->name, IFNAMSIZ);
 263         else {
 264                 int i;
 265                 for (i=1; i<100; i++) {
 266                         sprintf(name, "gre%d", i);
 267                         if (__dev_get_by_name(name) == NULL)
 268                                 break;
 269                 }
 270                 if (i==100)
 271                         goto failed;
 272         }
 273
 274         dev = alloc_netdev(sizeof(*t), name, ipgre_tunnel_setup);
 275         if (!dev)
 276           return NULL;
 277
 278         dev->init = ipgre_tunnel_init;
 279         nt = dev->priv;
 280         nt->parms = *parms;
 281
 282         if (register_netdevice(dev) < 0) {
 283                 free_netdev(dev);
 284                 goto failed;
 285         }
 286
 287         nt = dev->priv;
 288         nt->parms = *parms;
 289
 290         dev_hold(dev);
 291         ipgre_tunnel_link(nt);
 292         /* Do not decrement MOD_USE_COUNT here. */
 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 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_pmtu(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                         if (INET_ECN_is_not_ce(skb->nh.iph->tos))
 537                                 IP_ECN_set_ce(skb->nh.iph);
 538                 } else if (skb->protocol == htons(ETH_P_IPV6)) {
 539                         if (INET_ECN_is_not_ce(ip6_get_dsfield(skb->nh.ipv6h)))
 540                                 IP6_ECN_set_ce(skb->nh.ipv6h);
 541                 }
 542         }
 543 }
 544
 545 static inline u8
 546 ipgre_ecn_encapsulate(u8 tos, struct iphdr *old_iph, struct sk_buff *skb)
 547 {
 548         u8 inner = 0;
 549         if (skb->protocol == htons(ETH_P_IP))
 550                 inner = old_iph->tos;
 551         else if (skb->protocol == htons(ETH_P_IPV6))
 552                 inner = ip6_get_dsfield((struct ipv6hdr*)old_iph);
 553         return INET_ECN_encapsulate(tos, inner);
 554 }
 555
 556 int ipgre_rcv(struct sk_buff *skb)
 557 {
 558         struct iphdr *iph;
 559         u8     *h;
 560         u16    flags;
 561         u16    csum = 0;
 562         u32    key = 0;
 563         u32    seqno = 0;
 564         struct ip_tunnel *tunnel;
 565         int    offset = 4;
 566
 567         if (!pskb_may_pull(skb, 16))
 568                 goto drop_nolock;
 569
 570         iph = skb->nh.iph;
 571         h = skb->data;
 572         flags = *(u16*)h;
 573
 574         if (flags&(GRE_CSUM|GRE_KEY|GRE_ROUTING|GRE_SEQ|GRE_VERSION)) {
 575                 /* - Version must be 0.
 576                    - We do not support routing headers.
 577                  */
 578                 if (flags&(GRE_VERSION|GRE_ROUTING))
 579                         goto drop_nolock;
 580
 581                 if (flags&GRE_CSUM) {
 582                         if (skb->ip_summed == CHECKSUM_HW) {
 583                                 csum = (u16)csum_fold(skb->csum);
 584                                 if (csum)
 585                                         skb->ip_summed = CHECKSUM_NONE;
 586                         }
 587                         if (skb->ip_summed == CHECKSUM_NONE) {
 588                                 skb->csum = skb_checksum(skb, 0, skb->len, 0);
 589                                 skb->ip_summed = CHECKSUM_HW;
 590                                 csum = (u16)csum_fold(skb->csum);
 591                         }
 592                         offset += 4;
 593                 }
 594                 if (flags&GRE_KEY) {
 595                         key = *(u32*)(h + offset);
 596                         offset += 4;
 597                 }
 598                 if (flags&GRE_SEQ) {
 599                         seqno = ntohl(*(u32*)(h + offset));
 600                         offset += 4;
 601                 }
 602         }
 603
 604         read_lock(&ipgre_lock);
 605         if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) {
 606                 secpath_reset(skb);
 607
 608                 skb->mac.raw = skb->nh.raw;
 609                 skb->nh.raw = __pskb_pull(skb, offset);
 610                 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 611                 if (skb->ip_summed == CHECKSUM_HW)
 612                         skb->csum = csum_sub(skb->csum,
 613                                              csum_partial(skb->mac.raw, skb->nh.raw-skb->mac.raw, 0));
 614                 skb->protocol = *(u16*)(h + 2);
 615                 skb->pkt_type = PACKET_HOST;
 616 #ifdef CONFIG_NET_IPGRE_BROADCAST
 617                 if (MULTICAST(iph->daddr)) {
 618                         /* Looped back packet, drop it! */
 619                         if (((struct rtable*)skb->dst)->fl.iif == 0)
 620                                 goto drop;
 621                         tunnel->stat.multicast++;
 622                         skb->pkt_type = PACKET_BROADCAST;
 623                 }
 624 #endif
 625
 626                 if (((flags&GRE_CSUM) && csum) ||
 627                     (!(flags&GRE_CSUM) && tunnel->parms.i_flags&GRE_CSUM)) {
 628                         tunnel->stat.rx_crc_errors++;
 629                         tunnel->stat.rx_errors++;
 630                         goto drop;
 631                 }
 632                 if (tunnel->parms.i_flags&GRE_SEQ) {
 633                         if (!(flags&GRE_SEQ) ||
 634                             (tunnel->i_seqno && (s32)(seqno - tunnel->i_seqno) < 0)) {
 635                                 tunnel->stat.rx_fifo_errors++;
 636                                 tunnel->stat.rx_errors++;
 637                                 goto drop;
 638                         }
 639                         tunnel->i_seqno = seqno + 1;
 640                 }
 641                 tunnel->stat.rx_packets++;
 642                 tunnel->stat.rx_bytes += skb->len;
 643                 skb->dev = tunnel->dev;
 644                 dst_release(skb->dst);
 645                 skb->dst = NULL;
 646                 nf_reset(skb);
 647                 ipgre_ecn_decapsulate(iph, skb);
 648                 netif_rx(skb);
 649                 read_unlock(&ipgre_lock);
 650                 return(0);
 651         }
 652         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
 653
 654 drop:
 655         read_unlock(&ipgre_lock);
 656 drop_nolock:
 657         kfree_skb(skb);
 658         return(0);
 659 }
 660
 661 static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 662 {
 663         struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
 664         struct net_device_stats *stats = &tunnel->stat;
 665         struct iphdr  *old_iph = skb->nh.iph;
 666         struct iphdr  *tiph;
 667         u8     tos;
 668         u16    df;
 669         struct rtable *rt;                      /* Route to the other host */
 670         struct net_device *tdev;                        /* Device to other host */
 671         struct iphdr  *iph;                     /* Our new IP header */
 672         int    max_headroom;                    /* The extra header space needed */
 673         int    gre_hlen;
 674         u32    dst;
 675         int    mtu;
 676
 677         if (tunnel->recursion++) {
 678                 tunnel->stat.collisions++;
 679                 goto tx_error;
 680         }
 681
 682         if (dev->hard_header) {
 683                 gre_hlen = 0;
 684                 tiph = (struct iphdr*)skb->data;
 685         } else {
 686                 gre_hlen = tunnel->hlen;
 687                 tiph = &tunnel->parms.iph;
 688         }
 689
 690         if ((dst = tiph->daddr) == 0) {
 691                 /* NBMA tunnel */
 692
 693                 if (skb->dst == NULL) {
 694                         tunnel->stat.tx_fifo_errors++;
 695                         goto tx_error;
 696                 }
 697
 698                 if (skb->protocol == htons(ETH_P_IP)) {
 699                         rt = (struct rtable*)skb->dst;
 700                         if ((dst = rt->rt_gateway) == 0)
 701                                 goto tx_error_icmp;
 702                 }
 703 #ifdef CONFIG_IPV6
 704                 else if (skb->protocol == htons(ETH_P_IPV6)) {
 705                         struct in6_addr *addr6;
 706                         int addr_type;
 707                         struct neighbour *neigh = skb->dst->neighbour;
 708
 709                         if (neigh == NULL)
 710                                 goto tx_error;
 711
 712                         addr6 = (struct in6_addr*)&neigh->primary_key;
 713                         addr_type = ipv6_addr_type(addr6);
 714
 715                         if (addr_type == IPV6_ADDR_ANY) {
 716                                 addr6 = &skb->nh.ipv6h->daddr;
 717                                 addr_type = ipv6_addr_type(addr6);
 718                         }
 719
 720                         if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 721                                 goto tx_error_icmp;
 722
 723                         dst = addr6->s6_addr32[3];
 724                 }
 725 #endif
 726                 else
 727                         goto tx_error;
 728         }
 729
 730         tos = tiph->tos;
 731         if (tos&1) {
 732                 if (skb->protocol == htons(ETH_P_IP))
 733                         tos = old_iph->tos;
 734                 tos &= ~1;
 735         }
 736
 737         {
 738                 struct flowi fl = { .oif = tunnel->parms.link,
 739                                     .nl_u = { .ip4_u =
 740                                               { .daddr = dst,
 741                                                 .saddr = tiph->saddr,
 742                                                 .tos = RT_TOS(tos) } },
 743                                     .proto = IPPROTO_GRE };
 744                 if (ip_route_output_key(&rt, &fl)) {
 745                         tunnel->stat.tx_carrier_errors++;
 746                         goto tx_error;
 747                 }
 748         }
 749         tdev = rt->u.dst.dev;
 750
 751         if (tdev == dev) {
 752                 ip_rt_put(rt);
 753                 tunnel->stat.collisions++;
 754                 goto tx_error;
 755         }
 756
 757         df = tiph->frag_off;
 758         if (df)
 759                 mtu = dst_pmtu(&rt->u.dst) - tunnel->hlen;
 760         else
 761                 mtu = skb->dst ? dst_pmtu(skb->dst) : dev->mtu;
 762
 763         if (skb->dst)
 764                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 765
 766         if (skb->protocol == htons(ETH_P_IP)) {
 767                 df |= (old_iph->frag_off&htons(IP_DF));
 768
 769                 if ((old_iph->frag_off&htons(IP_DF)) &&
 770                     mtu < ntohs(old_iph->tot_len)) {
 771                         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
 772                         ip_rt_put(rt);
 773                         goto tx_error;
 774                 }
 775         }
 776 #ifdef CONFIG_IPV6
 777         else if (skb->protocol == htons(ETH_P_IPV6)) {
 778                 struct rt6_info *rt6 = (struct rt6_info*)skb->dst;
 779
 780                 if (rt6 && mtu < dst_pmtu(skb->dst) && mtu >= IPV6_MIN_MTU) {
 781                         if ((tunnel->parms.iph.daddr && !MULTICAST(tunnel->parms.iph.daddr)) ||
 782                             rt6->rt6i_dst.plen == 128) {
 783                                 rt6->rt6i_flags |= RTF_MODIFIED;
 784                                 skb->dst->metrics[RTAX_MTU-1] = mtu;
 785                         }
 786                 }
 787
 788                 if (mtu >= IPV6_MIN_MTU && mtu < skb->len - tunnel->hlen + gre_hlen) {
 789                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 790                         ip_rt_put(rt);
 791                         goto tx_error;
 792                 }
 793         }
 794 #endif
 795
 796         if (tunnel->err_count > 0) {
 797                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 798                         tunnel->err_count--;
 799
 800                         dst_link_failure(skb);
 801                 } else
 802                         tunnel->err_count = 0;
 803         }
 804
 805         max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen;
 806
 807         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 808                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 809                 if (!new_skb) {
 810                         ip_rt_put(rt);
 811                         stats->tx_dropped++;
 812                         dev_kfree_skb(skb);
 813                         tunnel->recursion--;
 814                         return 0;
 815                 }
 816                 if (skb->sk)
 817                         skb_set_owner_w(new_skb, skb->sk);
 818                 dev_kfree_skb(skb);
 819                 skb = new_skb;
 820                 old_iph = skb->nh.iph;
 821         }
 822
 823         skb->h.raw = skb->nh.raw;
 824         skb->nh.raw = skb_push(skb, gre_hlen);
 825         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 826         dst_release(skb->dst);
 827         skb->dst = &rt->u.dst;
 828
 829         /*
 830          *      Push down and install the IPIP header.
 831          */
 832
 833         iph                     =       skb->nh.iph;
 834         iph->version            =       4;
 835         iph->ihl                =       sizeof(struct iphdr) >> 2;
 836         iph->frag_off           =       df;
 837         iph->protocol           =       IPPROTO_GRE;
 838         iph->tos                =       ipgre_ecn_encapsulate(tos, old_iph, skb);
 839         iph->daddr              =       rt->rt_dst;
 840         iph->saddr              =       rt->rt_src;
 841
 842         if ((iph->ttl = tiph->ttl) == 0) {
 843                 if (skb->protocol == htons(ETH_P_IP))
 844                         iph->ttl = old_iph->ttl;
 845 #ifdef CONFIG_IPV6
 846                 else if (skb->protocol == htons(ETH_P_IPV6))
 847                         iph->ttl = ((struct ipv6hdr*)old_iph)->hop_limit;
 848 #endif
 849                 else
 850                         iph->ttl = dst_metric(&rt->u.dst, RTAX_HOPLIMIT);
 851         }
 852
 853         ((u16*)(iph+1))[0] = tunnel->parms.o_flags;
 854         ((u16*)(iph+1))[1] = skb->protocol;
 855
 856         if (tunnel->parms.o_flags&(GRE_KEY|GRE_CSUM|GRE_SEQ)) {
 857                 u32 *ptr = (u32*)(((u8*)iph) + tunnel->hlen - 4);
 858
 859                 if (tunnel->parms.o_flags&GRE_SEQ) {
 860                         ++tunnel->o_seqno;
 861                         *ptr = htonl(tunnel->o_seqno);
 862                         ptr--;
 863                 }
 864                 if (tunnel->parms.o_flags&GRE_KEY) {
 865                         *ptr = tunnel->parms.o_key;
 866                         ptr--;
 867                 }
 868                 if (tunnel->parms.o_flags&GRE_CSUM) {
 869                         *ptr = 0;
 870                         *(__u16*)ptr = ip_compute_csum((void*)(iph+1), skb->len - sizeof(struct iphdr));
 871                 }
 872         }
 873
 874         nf_reset(skb);
 875
 876         IPTUNNEL_XMIT();
 877         tunnel->recursion--;
 878         return 0;
 879
 880 tx_error_icmp:
 881         dst_link_failure(skb);
 882
 883 tx_error:
 884         stats->tx_errors++;
 885         dev_kfree_skb(skb);
 886         tunnel->recursion--;
 887         return 0;
 888 }
 889
 890 static int
 891 ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 892 {
 893         int err = 0;
 894         struct ip_tunnel_parm p;
 895         struct ip_tunnel *t;
 896
 897         switch (cmd) {
 898         case SIOCGETTUNNEL:
 899                 t = NULL;
 900                 if (dev == ipgre_fb_tunnel_dev) {
 901                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 902                                 err = -EFAULT;
 903                                 break;
 904                         }
 905                         t = ipgre_tunnel_locate(&p, 0);
 906                 }
 907                 if (t == NULL)
 908                         t = (struct ip_tunnel*)dev->priv;
 909                 memcpy(&p, &t->parms, sizeof(p));
 910                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 911                         err = -EFAULT;
 912                 break;
 913
 914         case SIOCADDTUNNEL:
 915         case SIOCCHGTUNNEL:
 916                 err = -EPERM;
 917                 if (!capable(CAP_NET_ADMIN))
 918                         goto done;
 919
 920                 err = -EFAULT;
 921                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 922                         goto done;
 923
 924                 err = -EINVAL;
 925                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_GRE ||
 926                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)) ||
 927                     ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING)))
 928                         goto done;
 929                 if (p.iph.ttl)
 930                         p.iph.frag_off |= htons(IP_DF);
 931
 932                 if (!(p.i_flags&GRE_KEY))
 933                         p.i_key = 0;
 934                 if (!(p.o_flags&GRE_KEY))
 935                         p.o_key = 0;
 936
 937                 t = ipgre_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 938
 939                 if (dev != ipgre_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 940                         if (t != NULL) {
 941                                 if (t->dev != dev) {
 942                                         err = -EEXIST;
 943                                         break;
 944                                 }
 945                         } else {
 946                                 unsigned nflags=0;
 947
 948                                 t = (struct ip_tunnel*)dev->priv;
 949
 950                                 if (MULTICAST(p.iph.daddr))
 951                                         nflags = IFF_BROADCAST;
 952                                 else if (p.iph.daddr)
 953                                         nflags = IFF_POINTOPOINT;
 954
 955                                 if ((dev->flags^nflags)&(IFF_POINTOPOINT|IFF_BROADCAST)) {
 956                                         err = -EINVAL;
 957                                         break;
 958                                 }
 959                                 ipgre_tunnel_unlink(t);
 960                                 t->parms.iph.saddr = p.iph.saddr;
 961                                 t->parms.iph.daddr = p.iph.daddr;
 962                                 t->parms.i_key = p.i_key;
 963                                 t->parms.o_key = p.o_key;
 964                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 965                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 966                                 ipgre_tunnel_link(t);
 967                                 netdev_state_change(dev);
 968                         }
 969                 }
 970
 971                 if (t) {
 972                         err = 0;
 973                         if (cmd == SIOCCHGTUNNEL) {
 974                                 t->parms.iph.ttl = p.iph.ttl;
 975                                 t->parms.iph.tos = p.iph.tos;
 976                                 t->parms.iph.frag_off = p.iph.frag_off;
 977                         }
 978                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 979                                 err = -EFAULT;
 980                 } else
 981                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 982                 break;
 983
 984         case SIOCDELTUNNEL:
 985                 err = -EPERM;
 986                 if (!capable(CAP_NET_ADMIN))
 987                         goto done;
 988
 989                 if (dev == ipgre_fb_tunnel_dev) {
 990                         err = -EFAULT;
 991                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 992                                 goto done;
 993                         err = -ENOENT;
 994                         if ((t = ipgre_tunnel_locate(&p, 0)) == NULL)
 995                                 goto done;
 996                         err = -EPERM;
 997                         if (t == ipgre_fb_tunnel_dev->priv)
 998                                 goto done;
 999                         dev = t->dev;
1000                 }
1001                 err = unregister_netdevice(dev);
1002                 break;
1003
1004         default:
1005                 err = -EINVAL;
1006         }
1007
1008 done:
1009         return err;
1010 }
1011
1012 static struct net_device_stats *ipgre_tunnel_get_stats(struct net_device *dev)
1013 {
1014         return &(((struct ip_tunnel*)dev->priv)->stat);
1015 }
1016
1017 static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1018 {
1019         struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
1020         if (new_mtu < 68 || new_mtu > 0xFFF8 - tunnel->hlen)
1021                 return -EINVAL;
1022         dev->mtu = new_mtu;
1023         return 0;
1024 }
1025
1026 #ifdef CONFIG_NET_IPGRE_BROADCAST
1027 /* Nice toy. Unfortunately, useless in real life :-)
1028    It allows to construct virtual multiprotocol broadcast "LAN"
1029    over the Internet, provided multicast routing is tuned.
1030
1031
1032    I have no idea was this bicycle invented before me,
1033    so that I had to set ARPHRD_IPGRE to a random value.
1034    I have an impression, that Cisco could make something similar,
1035    but this feature is apparently missing in IOS<=11.2(8).
1036
1037    I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks
1038    with broadcast 224.66.66.66. If you have access to mbone, play with me :-)
1039
1040    ping -t 255 224.66.66.66
1041
1042    If nobody answers, mbone does not work.
1043
1044    ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255
1045    ip addr add 10.66.66.<somewhat>/24 dev Universe
1046    ifconfig Universe up
1047    ifconfig Universe add fe80::<Your_real_addr>/10
1048    ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96
1049    ftp 10.66.66.66
1050    ...
1051    ftp fec0:6666:6666::193.233.7.65
1052    ...
1053
1054  */
1055
1056 static int ipgre_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
1057                         void *daddr, void *saddr, unsigned len)
1058 {
1059         struct ip_tunnel *t = (struct ip_tunnel*)dev->priv;
1060         struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen);
1061         u16 *p = (u16*)(iph+1);
1062
1063         memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
1064         p[0]            = t->parms.o_flags;
1065         p[1]            = htons(type);
1066
1067         /*
1068          *      Set the source hardware address.
1069          */
1070
1071         if (saddr)
1072                 memcpy(&iph->saddr, saddr, 4);
1073
1074         if (daddr) {
1075                 memcpy(&iph->daddr, daddr, 4);
1076                 return t->hlen;
1077         }
1078         if (iph->daddr && !MULTICAST(iph->daddr))
1079                 return t->hlen;
1080
1081         return -t->hlen;
1082 }
1083
1084 static int ipgre_open(struct net_device *dev)
1085 {
1086         struct ip_tunnel *t = (struct ip_tunnel*)dev->priv;
1087
1088         if (MULTICAST(t->parms.iph.daddr)) {
1089                 struct flowi fl = { .oif = t->parms.link,
1090                                     .nl_u = { .ip4_u =
1091                                               { .daddr = t->parms.iph.daddr,
1092                                                 .saddr = t->parms.iph.saddr,
1093                                                 .tos = RT_TOS(t->parms.iph.tos) } },
1094                                     .proto = IPPROTO_GRE };
1095                 struct rtable *rt;
1096                 if (ip_route_output_key(&rt, &fl))
1097                         return -EADDRNOTAVAIL;
1098                 dev = rt->u.dst.dev;
1099                 ip_rt_put(rt);
1100                 if (__in_dev_get(dev) == NULL)
1101                         return -EADDRNOTAVAIL;
1102                 t->mlink = dev->ifindex;
1103                 ip_mc_inc_group(__in_dev_get(dev), t->parms.iph.daddr);
1104         }
1105         return 0;
1106 }
1107
1108 static int ipgre_close(struct net_device *dev)
1109 {
1110         struct ip_tunnel *t = (struct ip_tunnel*)dev->priv;
1111         if (MULTICAST(t->parms.iph.daddr) && t->mlink) {
1112                 struct in_device *in_dev = inetdev_by_index(t->mlink);
1113                 if (in_dev) {
1114                         ip_mc_dec_group(in_dev, t->parms.iph.daddr);
1115                         in_dev_put(in_dev);
1116                 }
1117         }
1118         return 0;
1119 }
1120
1121 #endif
1122
1123 static void ipgre_tunnel_setup(struct net_device *dev)
1124 {
1125         SET_MODULE_OWNER(dev);
1126         dev->uninit             = ipgre_tunnel_uninit;
1127         dev->destructor         = free_netdev;
1128         dev->hard_start_xmit    = ipgre_tunnel_xmit;
1129         dev->get_stats          = ipgre_tunnel_get_stats;
1130         dev->do_ioctl           = ipgre_tunnel_ioctl;
1131         dev->change_mtu         = ipgre_tunnel_change_mtu;
1132
1133         dev->type               = ARPHRD_IPGRE;
1134         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr) + 4;
1135         dev->mtu                = 1500 - sizeof(struct iphdr) - 4;
1136         dev->flags              = IFF_NOARP;
1137         dev->iflink             = 0;
1138         dev->addr_len           = 4;
1139 }
1140
1141 static int ipgre_tunnel_init(struct net_device *dev)
1142 {
1143         struct net_device *tdev = NULL;
1144         struct ip_tunnel *tunnel;
1145         struct iphdr *iph;
1146         int hlen = LL_MAX_HEADER;
1147         int mtu = 1500;
1148         int addend = sizeof(struct iphdr) + 4;
1149
1150         tunnel = (struct ip_tunnel*)dev->priv;
1151         iph = &tunnel->parms.iph;
1152
1153         tunnel->dev = dev;
1154         strcpy(tunnel->parms.name, dev->name);
1155
1156         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1157         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1158
1159         /* Guess output device to choose reasonable mtu and hard_header_len */
1160
1161         if (iph->daddr) {
1162                 struct flowi fl = { .oif = tunnel->parms.link,
1163                                     .nl_u = { .ip4_u =
1164                                               { .daddr = iph->daddr,
1165                                                 .saddr = iph->saddr,
1166                                                 .tos = RT_TOS(iph->tos) } },
1167                                     .proto = IPPROTO_GRE };
1168                 struct rtable *rt;
1169                 if (!ip_route_output_key(&rt, &fl)) {
1170                         tdev = rt->u.dst.dev;
1171                         ip_rt_put(rt);
1172                 }
1173
1174                 dev->flags |= IFF_POINTOPOINT;
1175
1176 #ifdef CONFIG_NET_IPGRE_BROADCAST
1177                 if (MULTICAST(iph->daddr)) {
1178                         if (!iph->saddr)
1179                                 return -EINVAL;
1180                         dev->flags = IFF_BROADCAST;
1181                         dev->hard_header = ipgre_header;
1182                         dev->open = ipgre_open;
1183                         dev->stop = ipgre_close;
1184                 }
1185 #endif
1186         }
1187
1188         if (!tdev && tunnel->parms.link)
1189                 tdev = __dev_get_by_index(tunnel->parms.link);
1190
1191         if (tdev) {
1192                 hlen = tdev->hard_header_len;
1193                 mtu = tdev->mtu;
1194         }
1195         dev->iflink = tunnel->parms.link;
1196
1197         /* Precalculate GRE options length */
1198         if (tunnel->parms.o_flags&(GRE_CSUM|GRE_KEY|GRE_SEQ)) {
1199                 if (tunnel->parms.o_flags&GRE_CSUM)
1200                         addend += 4;
1201                 if (tunnel->parms.o_flags&GRE_KEY)
1202                         addend += 4;
1203                 if (tunnel->parms.o_flags&GRE_SEQ)
1204                         addend += 4;
1205         }
1206         dev->hard_header_len = hlen + addend;
1207         dev->mtu = mtu - addend;
1208         tunnel->hlen = addend;
1209         return 0;
1210 }
1211
1212 int __init ipgre_fb_tunnel_init(struct net_device *dev)
1213 {
1214         struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
1215         struct iphdr *iph = &tunnel->parms.iph;
1216
1217         tunnel->dev = dev;
1218         strcpy(tunnel->parms.name, dev->name);
1219
1220         iph->version            = 4;
1221         iph->protocol           = IPPROTO_GRE;
1222         iph->ihl                = 5;
1223         tunnel->hlen            = sizeof(struct iphdr) + 4;
1224
1225         dev_hold(dev);
1226         tunnels_wc[0]           = tunnel;
1227         return 0;
1228 }
1229
1230
1231 static struct net_protocol ipgre_protocol = {
1232         .handler        =       ipgre_rcv,
1233         .err_handler    =       ipgre_err,
1234 };
1235
1236
1237 /*
1238  *      And now the modules code and kernel interface.
1239  */
1240
1241 static int __init ipgre_init(void)
1242 {
1243         int err = -EINVAL;
1244
1245         printk(KERN_INFO "GRE over IPv4 tunneling driver\n");
1246
1247         if (inet_add_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) {
1248                 printk(KERN_INFO "ipgre init: can't add protocol\n");
1249                 return -EAGAIN;
1250         }
1251
1252         ipgre_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0",
1253                                            ipgre_tunnel_setup);
1254         if (!ipgre_fb_tunnel_dev) {
1255                 err = -ENOMEM;
1256                 goto fail;
1257         }
1258
1259         ipgre_fb_tunnel_dev->init = ipgre_fb_tunnel_init;
1260
1261         if ((err = register_netdev(ipgre_fb_tunnel_dev)))
1262                 goto fail;
1263 out:
1264         return err;
1265 fail:
1266         inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
1267         free_netdev(ipgre_fb_tunnel_dev);
1268         goto out;
1269 }
1270
1271 void ipgre_fini(void)
1272 {
1273         if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0)
1274                 printk(KERN_INFO "ipgre close: can't remove protocol\n");
1275
1276         unregister_netdev(ipgre_fb_tunnel_dev);
1277 }
1278
1279 module_init(ipgre_init);
1280 module_exit(ipgre_fini);
1281 MODULE_LICENSE("GPL");