git.oblomov.eu Git - linux-2.6/blob - 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                         switch (skb->ip_summed) {
 581                         case CHECKSUM_HW:
 582                                 csum = (u16)csum_fold(skb->csum);
 583                                 if (!csum)
 584                                         break;
 585                                 /* fall through */
 586                         case CHECKSUM_NONE:
 587                                 skb->csum = 0;
 588                                 csum = __skb_checksum_complete(skb);
 589                                 skb->ip_summed = CHECKSUM_HW;
 590                         }
 591                         offset += 4;
 592                 }
 593                 if (flags&GRE_KEY) {
 594                         key = *(u32*)(h + offset);
 595                         offset += 4;
 596                 }
 597                 if (flags&GRE_SEQ) {
 598                         seqno = ntohl(*(u32*)(h + offset));
 599                         offset += 4;
 600                 }
 601         }
 602
 603         read_lock(&ipgre_lock);
 604         if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) {
 605                 secpath_reset(skb);
 606
 607                 skb->protocol = *(u16*)(h + 2);
 608                 /* WCCP version 1 and 2 protocol decoding.
 609                  * - Change protocol to IP
 610                  * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
 611                  */
 612                 if (flags == 0 &&
 613                     skb->protocol == __constant_htons(ETH_P_WCCP)) {
 614                         skb->protocol = __constant_htons(ETH_P_IP);
 615                         if ((*(h + offset) & 0xF0) != 0x40)
 616                                 offset += 4;
 617                 }
 618
 619                 skb->mac.raw = skb->nh.raw;
 620                 skb->nh.raw = __pskb_pull(skb, offset);
 621                 skb_postpull_rcsum(skb, skb->mac.raw, offset);
 622                 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 623                 skb->pkt_type = PACKET_HOST;
 624 #ifdef CONFIG_NET_IPGRE_BROADCAST
 625                 if (MULTICAST(iph->daddr)) {
 626                         /* Looped back packet, drop it! */
 627                         if (((struct rtable*)skb->dst)->fl.iif == 0)
 628                                 goto drop;
 629                         tunnel->stat.multicast++;
 630                         skb->pkt_type = PACKET_BROADCAST;
 631                 }
 632 #endif
 633
 634                 if (((flags&GRE_CSUM) && csum) ||
 635                     (!(flags&GRE_CSUM) && tunnel->parms.i_flags&GRE_CSUM)) {
 636                         tunnel->stat.rx_crc_errors++;
 637                         tunnel->stat.rx_errors++;
 638                         goto drop;
 639                 }
 640                 if (tunnel->parms.i_flags&GRE_SEQ) {
 641                         if (!(flags&GRE_SEQ) ||
 642                             (tunnel->i_seqno && (s32)(seqno - tunnel->i_seqno) < 0)) {
 643                                 tunnel->stat.rx_fifo_errors++;
 644                                 tunnel->stat.rx_errors++;
 645                                 goto drop;
 646                         }
 647                         tunnel->i_seqno = seqno + 1;
 648                 }
 649                 tunnel->stat.rx_packets++;
 650                 tunnel->stat.rx_bytes += skb->len;
 651                 skb->dev = tunnel->dev;
 652                 dst_release(skb->dst);
 653                 skb->dst = NULL;
 654                 nf_reset(skb);
 655                 ipgre_ecn_decapsulate(iph, skb);
 656                 netif_rx(skb);
 657                 read_unlock(&ipgre_lock);
 658                 return(0);
 659         }
 660         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
 661
 662 drop:
 663         read_unlock(&ipgre_lock);
 664 drop_nolock:
 665         kfree_skb(skb);
 666         return(0);
 667 }
 668
 669 static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 670 {
 671         struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
 672         struct net_device_stats *stats = &tunnel->stat;
 673         struct iphdr  *old_iph = skb->nh.iph;
 674         struct iphdr  *tiph;
 675         u8     tos;
 676         u16    df;
 677         struct rtable *rt;                      /* Route to the other host */
 678         struct net_device *tdev;                        /* Device to other host */
 679         struct iphdr  *iph;                     /* Our new IP header */
 680         int    max_headroom;                    /* The extra header space needed */
 681         int    gre_hlen;
 682         u32    dst;
 683         int    mtu;
 684
 685         if (tunnel->recursion++) {
 686                 tunnel->stat.collisions++;
 687                 goto tx_error;
 688         }
 689
 690         if (dev->hard_header) {
 691                 gre_hlen = 0;
 692                 tiph = (struct iphdr*)skb->data;
 693         } else {
 694                 gre_hlen = tunnel->hlen;
 695                 tiph = &tunnel->parms.iph;
 696         }
 697
 698         if ((dst = tiph->daddr) == 0) {
 699                 /* NBMA tunnel */
 700
 701                 if (skb->dst == NULL) {
 702                         tunnel->stat.tx_fifo_errors++;
 703                         goto tx_error;
 704                 }
 705
 706                 if (skb->protocol == htons(ETH_P_IP)) {
 707                         rt = (struct rtable*)skb->dst;
 708                         if ((dst = rt->rt_gateway) == 0)
 709                                 goto tx_error_icmp;
 710                 }
 711 #ifdef CONFIG_IPV6
 712                 else if (skb->protocol == htons(ETH_P_IPV6)) {
 713                         struct in6_addr *addr6;
 714                         int addr_type;
 715                         struct neighbour *neigh = skb->dst->neighbour;
 716
 717                         if (neigh == NULL)
 718                                 goto tx_error;
 719
 720                         addr6 = (struct in6_addr*)&neigh->primary_key;
 721                         addr_type = ipv6_addr_type(addr6);
 722
 723                         if (addr_type == IPV6_ADDR_ANY) {
 724                                 addr6 = &skb->nh.ipv6h->daddr;
 725                                 addr_type = ipv6_addr_type(addr6);
 726                         }
 727
 728                         if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 729                                 goto tx_error_icmp;
 730
 731                         dst = addr6->s6_addr32[3];
 732                 }
 733 #endif
 734                 else
 735                         goto tx_error;
 736         }
 737
 738         tos = tiph->tos;
 739         if (tos&1) {
 740                 if (skb->protocol == htons(ETH_P_IP))
 741                         tos = old_iph->tos;
 742                 tos &= ~1;
 743         }
 744
 745         {
 746                 struct flowi fl = { .oif = tunnel->parms.link,
 747                                     .nl_u = { .ip4_u =
 748                                               { .daddr = dst,
 749                                                 .saddr = tiph->saddr,
 750                                                 .tos = RT_TOS(tos) } },
 751                                     .proto = IPPROTO_GRE };
 752                 if (ip_route_output_key(&rt, &fl)) {
 753                         tunnel->stat.tx_carrier_errors++;
 754                         goto tx_error;
 755                 }
 756         }
 757         tdev = rt->u.dst.dev;
 758
 759         if (tdev == dev) {
 760                 ip_rt_put(rt);
 761                 tunnel->stat.collisions++;
 762                 goto tx_error;
 763         }
 764
 765         df = tiph->frag_off;
 766         if (df)
 767                 mtu = dst_mtu(&rt->u.dst) - tunnel->hlen;
 768         else
 769                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 770
 771         if (skb->dst)
 772                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 773
 774         if (skb->protocol == htons(ETH_P_IP)) {
 775                 df |= (old_iph->frag_off&htons(IP_DF));
 776
 777                 if ((old_iph->frag_off&htons(IP_DF)) &&
 778                     mtu < ntohs(old_iph->tot_len)) {
 779                         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
 780                         ip_rt_put(rt);
 781                         goto tx_error;
 782                 }
 783         }
 784 #ifdef CONFIG_IPV6
 785         else if (skb->protocol == htons(ETH_P_IPV6)) {
 786                 struct rt6_info *rt6 = (struct rt6_info*)skb->dst;
 787
 788                 if (rt6 && mtu < dst_mtu(skb->dst) && mtu >= IPV6_MIN_MTU) {
 789                         if ((tunnel->parms.iph.daddr && !MULTICAST(tunnel->parms.iph.daddr)) ||
 790                             rt6->rt6i_dst.plen == 128) {
 791                                 rt6->rt6i_flags |= RTF_MODIFIED;
 792                                 skb->dst->metrics[RTAX_MTU-1] = mtu;
 793                         }
 794                 }
 795
 796                 if (mtu >= IPV6_MIN_MTU && mtu < skb->len - tunnel->hlen + gre_hlen) {
 797                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 798                         ip_rt_put(rt);
 799                         goto tx_error;
 800                 }
 801         }
 802 #endif
 803
 804         if (tunnel->err_count > 0) {
 805                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 806                         tunnel->err_count--;
 807
 808                         dst_link_failure(skb);
 809                 } else
 810                         tunnel->err_count = 0;
 811         }
 812
 813         max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen;
 814
 815         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 816                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 817                 if (!new_skb) {
 818                         ip_rt_put(rt);
 819                         stats->tx_dropped++;
 820                         dev_kfree_skb(skb);
 821                         tunnel->recursion--;
 822                         return 0;
 823                 }
 824                 if (skb->sk)
 825                         skb_set_owner_w(new_skb, skb->sk);
 826                 dev_kfree_skb(skb);
 827                 skb = new_skb;
 828                 old_iph = skb->nh.iph;
 829         }
 830
 831         skb->h.raw = skb->nh.raw;
 832         skb->nh.raw = skb_push(skb, gre_hlen);
 833         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 834         dst_release(skb->dst);
 835         skb->dst = &rt->u.dst;
 836
 837         /*
 838          *      Push down and install the IPIP header.
 839          */
 840
 841         iph                     =       skb->nh.iph;
 842         iph->version            =       4;
 843         iph->ihl                =       sizeof(struct iphdr) >> 2;
 844         iph->frag_off           =       df;
 845         iph->protocol           =       IPPROTO_GRE;
 846         iph->tos                =       ipgre_ecn_encapsulate(tos, old_iph, skb);
 847         iph->daddr              =       rt->rt_dst;
 848         iph->saddr              =       rt->rt_src;
 849
 850         if ((iph->ttl = tiph->ttl) == 0) {
 851                 if (skb->protocol == htons(ETH_P_IP))
 852                         iph->ttl = old_iph->ttl;
 853 #ifdef CONFIG_IPV6
 854                 else if (skb->protocol == htons(ETH_P_IPV6))
 855                         iph->ttl = ((struct ipv6hdr*)old_iph)->hop_limit;
 856 #endif
 857                 else
 858                         iph->ttl = dst_metric(&rt->u.dst, RTAX_HOPLIMIT);
 859         }
 860
 861         ((u16*)(iph+1))[0] = tunnel->parms.o_flags;
 862         ((u16*)(iph+1))[1] = skb->protocol;
 863
 864         if (tunnel->parms.o_flags&(GRE_KEY|GRE_CSUM|GRE_SEQ)) {
 865                 u32 *ptr = (u32*)(((u8*)iph) + tunnel->hlen - 4);
 866
 867                 if (tunnel->parms.o_flags&GRE_SEQ) {
 868                         ++tunnel->o_seqno;
 869                         *ptr = htonl(tunnel->o_seqno);
 870                         ptr--;
 871                 }
 872                 if (tunnel->parms.o_flags&GRE_KEY) {
 873                         *ptr = tunnel->parms.o_key;
 874                         ptr--;
 875                 }
 876                 if (tunnel->parms.o_flags&GRE_CSUM) {
 877                         *ptr = 0;
 878                         *(__u16*)ptr = ip_compute_csum((void*)(iph+1), skb->len - sizeof(struct iphdr));
 879                 }
 880         }
 881
 882         nf_reset(skb);
 883
 884         IPTUNNEL_XMIT();
 885         tunnel->recursion--;
 886         return 0;
 887
 888 tx_error_icmp:
 889         dst_link_failure(skb);
 890
 891 tx_error:
 892         stats->tx_errors++;
 893         dev_kfree_skb(skb);
 894         tunnel->recursion--;
 895         return 0;
 896 }
 897
 898 static int
 899 ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 900 {
 901         int err = 0;
 902         struct ip_tunnel_parm p;
 903         struct ip_tunnel *t;
 904
 905         switch (cmd) {
 906         case SIOCGETTUNNEL:
 907                 t = NULL;
 908                 if (dev == ipgre_fb_tunnel_dev) {
 909                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 910                                 err = -EFAULT;
 911                                 break;
 912                         }
 913                         t = ipgre_tunnel_locate(&p, 0);
 914                 }
 915                 if (t == NULL)
 916                         t = (struct ip_tunnel*)dev->priv;
 917                 memcpy(&p, &t->parms, sizeof(p));
 918                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 919                         err = -EFAULT;
 920                 break;
 921
 922         case SIOCADDTUNNEL:
 923         case SIOCCHGTUNNEL:
 924                 err = -EPERM;
 925                 if (!capable(CAP_NET_ADMIN))
 926                         goto done;
 927
 928                 err = -EFAULT;
 929                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 930                         goto done;
 931
 932                 err = -EINVAL;
 933                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_GRE ||
 934                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)) ||
 935                     ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING)))
 936                         goto done;
 937                 if (p.iph.ttl)
 938                         p.iph.frag_off |= htons(IP_DF);
 939
 940                 if (!(p.i_flags&GRE_KEY))
 941                         p.i_key = 0;
 942                 if (!(p.o_flags&GRE_KEY))
 943                         p.o_key = 0;
 944
 945                 t = ipgre_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 946
 947                 if (dev != ipgre_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 948                         if (t != NULL) {
 949                                 if (t->dev != dev) {
 950                                         err = -EEXIST;
 951                                         break;
 952                                 }
 953                         } else {
 954                                 unsigned nflags=0;
 955
 956                                 t = (struct ip_tunnel*)dev->priv;
 957
 958                                 if (MULTICAST(p.iph.daddr))
 959                                         nflags = IFF_BROADCAST;
 960                                 else if (p.iph.daddr)
 961                                         nflags = IFF_POINTOPOINT;
 962
 963                                 if ((dev->flags^nflags)&(IFF_POINTOPOINT|IFF_BROADCAST)) {
 964                                         err = -EINVAL;
 965                                         break;
 966                                 }
 967                                 ipgre_tunnel_unlink(t);
 968                                 t->parms.iph.saddr = p.iph.saddr;
 969                                 t->parms.iph.daddr = p.iph.daddr;
 970                                 t->parms.i_key = p.i_key;
 971                                 t->parms.o_key = p.o_key;
 972                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 973                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 974                                 ipgre_tunnel_link(t);
 975                                 netdev_state_change(dev);
 976                         }
 977                 }
 978
 979                 if (t) {
 980                         err = 0;
 981                         if (cmd == SIOCCHGTUNNEL) {
 982                                 t->parms.iph.ttl = p.iph.ttl;
 983                                 t->parms.iph.tos = p.iph.tos;
 984                                 t->parms.iph.frag_off = p.iph.frag_off;
 985                         }
 986                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 987                                 err = -EFAULT;
 988                 } else
 989                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 990                 break;
 991
 992         case SIOCDELTUNNEL:
 993                 err = -EPERM;
 994                 if (!capable(CAP_NET_ADMIN))
 995                         goto done;
 996
 997                 if (dev == ipgre_fb_tunnel_dev) {
 998                         err = -EFAULT;
 999                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
1000                                 goto done;
1001                         err = -ENOENT;
1002                         if ((t = ipgre_tunnel_locate(&p, 0)) == NULL)
1003                                 goto done;
1004                         err = -EPERM;
1005                         if (t == ipgre_fb_tunnel_dev->priv)
1006                                 goto done;
1007                         dev = t->dev;
1008                 }
1009                 err = unregister_netdevice(dev);
1010                 break;
1011
1012         default:
1013                 err = -EINVAL;
1014         }
1015
1016 done:
1017         return err;
1018 }
1019
1020 static struct net_device_stats *ipgre_tunnel_get_stats(struct net_device *dev)
1021 {
1022         return &(((struct ip_tunnel*)dev->priv)->stat);
1023 }
1024
1025 static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1026 {
1027         struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
1028         if (new_mtu < 68 || new_mtu > 0xFFF8 - tunnel->hlen)
1029                 return -EINVAL;
1030         dev->mtu = new_mtu;
1031         return 0;
1032 }
1033
1034 #ifdef CONFIG_NET_IPGRE_BROADCAST
1035 /* Nice toy. Unfortunately, useless in real life :-)
1036    It allows to construct virtual multiprotocol broadcast "LAN"
1037    over the Internet, provided multicast routing is tuned.
1038
1039
1040    I have no idea was this bicycle invented before me,
1041    so that I had to set ARPHRD_IPGRE to a random value.
1042    I have an impression, that Cisco could make something similar,
1043    but this feature is apparently missing in IOS<=11.2(8).
1044
1045    I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks
1046    with broadcast 224.66.66.66. If you have access to mbone, play with me :-)
1047
1048    ping -t 255 224.66.66.66
1049
1050    If nobody answers, mbone does not work.
1051
1052    ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255
1053    ip addr add 10.66.66.<somewhat>/24 dev Universe
1054    ifconfig Universe up
1055    ifconfig Universe add fe80::<Your_real_addr>/10
1056    ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96
1057    ftp 10.66.66.66
1058    ...
1059    ftp fec0:6666:6666::193.233.7.65
1060    ...
1061
1062  */
1063
1064 static int ipgre_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
1065                         void *daddr, void *saddr, unsigned len)
1066 {
1067         struct ip_tunnel *t = (struct ip_tunnel*)dev->priv;
1068         struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen);
1069         u16 *p = (u16*)(iph+1);
1070
1071         memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
1072         p[0]            = t->parms.o_flags;
1073         p[1]            = htons(type);
1074
1075         /*
1076          *      Set the source hardware address.
1077          */
1078
1079         if (saddr)
1080                 memcpy(&iph->saddr, saddr, 4);
1081
1082         if (daddr) {
1083                 memcpy(&iph->daddr, daddr, 4);
1084                 return t->hlen;
1085         }
1086         if (iph->daddr && !MULTICAST(iph->daddr))
1087                 return t->hlen;
1088
1089         return -t->hlen;
1090 }
1091
1092 static int ipgre_open(struct net_device *dev)
1093 {
1094         struct ip_tunnel *t = (struct ip_tunnel*)dev->priv;
1095
1096         if (MULTICAST(t->parms.iph.daddr)) {
1097                 struct flowi fl = { .oif = t->parms.link,
1098                                     .nl_u = { .ip4_u =
1099                                               { .daddr = t->parms.iph.daddr,
1100                                                 .saddr = t->parms.iph.saddr,
1101                                                 .tos = RT_TOS(t->parms.iph.tos) } },
1102                                     .proto = IPPROTO_GRE };
1103                 struct rtable *rt;
1104                 if (ip_route_output_key(&rt, &fl))
1105                         return -EADDRNOTAVAIL;
1106                 dev = rt->u.dst.dev;
1107                 ip_rt_put(rt);
1108                 if (__in_dev_get_rtnl(dev) == NULL)
1109                         return -EADDRNOTAVAIL;
1110                 t->mlink = dev->ifindex;
1111                 ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);
1112         }
1113         return 0;
1114 }
1115
1116 static int ipgre_close(struct net_device *dev)
1117 {
1118         struct ip_tunnel *t = (struct ip_tunnel*)dev->priv;
1119         if (MULTICAST(t->parms.iph.daddr) && t->mlink) {
1120                 struct in_device *in_dev = inetdev_by_index(t->mlink);
1121                 if (in_dev) {
1122                         ip_mc_dec_group(in_dev, t->parms.iph.daddr);
1123                         in_dev_put(in_dev);
1124                 }
1125         }
1126         return 0;
1127 }
1128
1129 #endif
1130
1131 static void ipgre_tunnel_setup(struct net_device *dev)
1132 {
1133         SET_MODULE_OWNER(dev);
1134         dev->uninit             = ipgre_tunnel_uninit;
1135         dev->destructor         = free_netdev;
1136         dev->hard_start_xmit    = ipgre_tunnel_xmit;
1137         dev->get_stats          = ipgre_tunnel_get_stats;
1138         dev->do_ioctl           = ipgre_tunnel_ioctl;
1139         dev->change_mtu         = ipgre_tunnel_change_mtu;
1140
1141         dev->type               = ARPHRD_IPGRE;
1142         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr) + 4;
1143         dev->mtu                = 1500 - sizeof(struct iphdr) - 4;
1144         dev->flags              = IFF_NOARP;
1145         dev->iflink             = 0;
1146         dev->addr_len           = 4;
1147 }
1148
1149 static int ipgre_tunnel_init(struct net_device *dev)
1150 {
1151         struct net_device *tdev = NULL;
1152         struct ip_tunnel *tunnel;
1153         struct iphdr *iph;
1154         int hlen = LL_MAX_HEADER;
1155         int mtu = 1500;
1156         int addend = sizeof(struct iphdr) + 4;
1157
1158         tunnel = (struct ip_tunnel*)dev->priv;
1159         iph = &tunnel->parms.iph;
1160
1161         tunnel->dev = dev;
1162         strcpy(tunnel->parms.name, dev->name);
1163
1164         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1165         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1166
1167         /* Guess output device to choose reasonable mtu and hard_header_len */
1168
1169         if (iph->daddr) {
1170                 struct flowi fl = { .oif = tunnel->parms.link,
1171                                     .nl_u = { .ip4_u =
1172                                               { .daddr = iph->daddr,
1173                                                 .saddr = iph->saddr,
1174                                                 .tos = RT_TOS(iph->tos) } },
1175                                     .proto = IPPROTO_GRE };
1176                 struct rtable *rt;
1177                 if (!ip_route_output_key(&rt, &fl)) {
1178                         tdev = rt->u.dst.dev;
1179                         ip_rt_put(rt);
1180                 }
1181
1182                 dev->flags |= IFF_POINTOPOINT;
1183
1184 #ifdef CONFIG_NET_IPGRE_BROADCAST
1185                 if (MULTICAST(iph->daddr)) {
1186                         if (!iph->saddr)
1187                                 return -EINVAL;
1188                         dev->flags = IFF_BROADCAST;
1189                         dev->hard_header = ipgre_header;
1190                         dev->open = ipgre_open;
1191                         dev->stop = ipgre_close;
1192                 }
1193 #endif
1194         }
1195
1196         if (!tdev && tunnel->parms.link)
1197                 tdev = __dev_get_by_index(tunnel->parms.link);
1198
1199         if (tdev) {
1200                 hlen = tdev->hard_header_len;
1201                 mtu = tdev->mtu;
1202         }
1203         dev->iflink = tunnel->parms.link;
1204
1205         /* Precalculate GRE options length */
1206         if (tunnel->parms.o_flags&(GRE_CSUM|GRE_KEY|GRE_SEQ)) {
1207                 if (tunnel->parms.o_flags&GRE_CSUM)
1208                         addend += 4;
1209                 if (tunnel->parms.o_flags&GRE_KEY)
1210                         addend += 4;
1211                 if (tunnel->parms.o_flags&GRE_SEQ)
1212                         addend += 4;
1213         }
1214         dev->hard_header_len = hlen + addend;
1215         dev->mtu = mtu - addend;
1216         tunnel->hlen = addend;
1217         return 0;
1218 }
1219
1220 int __init ipgre_fb_tunnel_init(struct net_device *dev)
1221 {
1222         struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
1223         struct iphdr *iph = &tunnel->parms.iph;
1224
1225         tunnel->dev = dev;
1226         strcpy(tunnel->parms.name, dev->name);
1227
1228         iph->version            = 4;
1229         iph->protocol           = IPPROTO_GRE;
1230         iph->ihl                = 5;
1231         tunnel->hlen            = sizeof(struct iphdr) + 4;
1232
1233         dev_hold(dev);
1234         tunnels_wc[0]           = tunnel;
1235         return 0;
1236 }
1237
1238
1239 static struct net_protocol ipgre_protocol = {
1240         .handler        =       ipgre_rcv,
1241         .err_handler    =       ipgre_err,
1242 };
1243
1244
1245 /*
1246  *      And now the modules code and kernel interface.
1247  */
1248
1249 static int __init ipgre_init(void)
1250 {
1251         int err;
1252
1253         printk(KERN_INFO "GRE over IPv4 tunneling driver\n");
1254
1255         if (inet_add_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) {
1256                 printk(KERN_INFO "ipgre init: can't add protocol\n");
1257                 return -EAGAIN;
1258         }
1259
1260         ipgre_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0",
1261                                            ipgre_tunnel_setup);
1262         if (!ipgre_fb_tunnel_dev) {
1263                 err = -ENOMEM;
1264                 goto err1;
1265         }
1266
1267         ipgre_fb_tunnel_dev->init = ipgre_fb_tunnel_init;
1268
1269         if ((err = register_netdev(ipgre_fb_tunnel_dev)))
1270                 goto err2;
1271 out:
1272         return err;
1273 err2:
1274         free_netdev(ipgre_fb_tunnel_dev);
1275 err1:
1276         inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
1277         goto out;
1278 }
1279
1280 static void __exit ipgre_destroy_tunnels(void)
1281 {
1282         int prio;
1283
1284         for (prio = 0; prio < 4; prio++) {
1285                 int h;
1286                 for (h = 0; h < HASH_SIZE; h++) {
1287                         struct ip_tunnel *t;
1288                         while ((t = tunnels[prio][h]) != NULL)
1289                                 unregister_netdevice(t->dev);
1290                 }
1291         }
1292 }
1293
1294 static void __exit ipgre_fini(void)
1295 {
1296         if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0)
1297                 printk(KERN_INFO "ipgre close: can't remove protocol\n");
1298
1299         rtnl_lock();
1300         ipgre_destroy_tunnels();
1301         rtnl_unlock();
1302 }
1303
1304 module_init(ipgre_init);
1305 module_exit(ipgre_fini);
1306 MODULE_LICENSE("GPL");