net/ipv4/ip_gre.c

   1 /*
   2  *      Linux NET3:     GRE over IP protocol decoder.
   3  *
   4  *      Authors: Alexey Kuznetsov (kuznet@ms2.inr.ac.ru)
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  *
  11  */
  12
  13 #include <linux/capability.h>
  14 #include <linux/module.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <asm/uaccess.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/in.h>
  21 #include <linux/tcp.h>
  22 #include <linux/udp.h>
  23 #include <linux/if_arp.h>
  24 #include <linux/mroute.h>
  25 #include <linux/init.h>
  26 #include <linux/in6.h>
  27 #include <linux/inetdevice.h>
  28 #include <linux/igmp.h>
  29 #include <linux/netfilter_ipv4.h>
  30 #include <linux/if_ether.h>
  31
  32 #include <net/sock.h>
  33 #include <net/ip.h>
  34 #include <net/icmp.h>
  35 #include <net/protocol.h>
  36 #include <net/ipip.h>
  37 #include <net/arp.h>
  38 #include <net/checksum.h>
  39 #include <net/dsfield.h>
  40 #include <net/inet_ecn.h>
  41 #include <net/xfrm.h>
  42
  43 #ifdef CONFIG_IPV6
  44 #include <net/ipv6.h>
  45 #include <net/ip6_fib.h>
  46 #include <net/ip6_route.h>
  47 #endif
  48
  49 /*
  50    Problems & solutions
  51    --------------------
  52
  53    1. The most important issue is detecting local dead loops.
  54    They would cause complete host lockup in transmit, which
  55    would be "resolved" by stack overflow or, if queueing is enabled,
  56    with infinite looping in net_bh.
  57
  58    We cannot track such dead loops during route installation,
  59    it is infeasible task. The most general solutions would be
  60    to keep skb->encapsulation counter (sort of local ttl),
  61    and silently drop packet when it expires. It is the best
  62    solution, but it supposes maintaing new variable in ALL
  63    skb, even if no tunneling is used.
  64
  65    Current solution: t->recursion lock breaks dead loops. It looks
  66    like dev->tbusy flag, but I preferred new variable, because
  67    the semantics is different. One day, when hard_start_xmit
  68    will be multithreaded we will have to use skb->encapsulation.
  69
  70
  71
  72    2. Networking dead loops would not kill routers, but would really
  73    kill network. IP hop limit plays role of "t->recursion" in this case,
  74    if we copy it from packet being encapsulated to upper header.
  75    It is very good solution, but it introduces two problems:
  76
  77    - Routing protocols, using packets with ttl=1 (OSPF, RIP2),
  78      do not work over tunnels.
  79    - traceroute does not work. I planned to relay ICMP from tunnel,
  80      so that this problem would be solved and traceroute output
  81      would even more informative. This idea appeared to be wrong:
  82      only Linux complies to rfc1812 now (yes, guys, Linux is the only
  83      true router now :-)), all routers (at least, in neighbourhood of mine)
  84      return only 8 bytes of payload. It is the end.
  85
  86    Hence, if we want that OSPF worked or traceroute said something reasonable,
  87    we should search for another solution.
  88
  89    One of them is to parse packet trying to detect inner encapsulation
  90    made by our node. It is difficult or even impossible, especially,
  91    taking into account fragmentation. TO be short, tt is not solution at all.
  92
  93    Current solution: The solution was UNEXPECTEDLY SIMPLE.
  94    We force DF flag on tunnels with preconfigured hop limit,
  95    that is ALL. :-) Well, it does not remove the problem completely,
  96    but exponential growth of network traffic is changed to linear
  97    (branches, that exceed pmtu are pruned) and tunnel mtu
  98    fastly degrades to value <68, where looping stops.
  99    Yes, it is not good if there exists a router in the loop,
 100    which does not force DF, even when encapsulating packets have DF set.
 101    But it is not our problem! Nobody could accuse us, we made
 102    all that we could make. Even if it is your gated who injected
 103    fatal route to network, even if it were you who configured
 104    fatal static route: you are innocent. :-)
 105
 106
 107
 108    3. Really, ipv4/ipip.c, ipv4/ip_gre.c and ipv6/sit.c contain
 109    practically identical code. It would be good to glue them
 110    together, but it is not very evident, how to make them modular.
 111    sit is integral part of IPv6, ipip and gre are naturally modular.
 112    We could extract common parts (hash table, ioctl etc)
 113    to a separate module (ip_tunnel.c).
 114
 115    Alexey Kuznetsov.
 116  */
 117
 118 static int ipgre_tunnel_init(struct net_device *dev);
 119 static void ipgre_tunnel_setup(struct net_device *dev);
 120
 121 /* Fallback tunnel: no source, no destination, no key, no options */
 122
 123 static int ipgre_fb_tunnel_init(struct net_device *dev);
 124
 125 static struct net_device *ipgre_fb_tunnel_dev;
 126
 127 /* Tunnel hash table */
 128
 129 /*
 130    4 hash tables:
 131
 132    3: (remote,local)
 133    2: (remote,*)
 134    1: (*,local)
 135    0: (*,*)
 136
 137    We require exact key match i.e. if a key is present in packet
 138    it will match only tunnel with the same key; if it is not present,
 139    it will match only keyless tunnel.
 140
 141    All keysless packets, if not matched configured keyless tunnels
 142    will match fallback tunnel.
 143  */
 144
 145 #define HASH_SIZE  16
 146 #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
 147
 148 static struct ip_tunnel *tunnels[4][HASH_SIZE];
 149
 150 #define tunnels_r_l     (tunnels[3])
 151 #define tunnels_r       (tunnels[2])
 152 #define tunnels_l       (tunnels[1])
 153 #define tunnels_wc      (tunnels[0])
 154
 155 static DEFINE_RWLOCK(ipgre_lock);
 156
 157 /* Given src, dst and key, find appropriate for input tunnel. */
 158
 159 static struct ip_tunnel * ipgre_tunnel_lookup(__be32 remote, __be32 local, __be32 key)
 160 {
 161         unsigned h0 = HASH(remote);
 162         unsigned h1 = HASH(key);
 163         struct ip_tunnel *t;
 164
 165         for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
 166                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
 167                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 168                                 return t;
 169                 }
 170         }
 171         for (t = tunnels_r[h0^h1]; t; t = t->next) {
 172                 if (remote == t->parms.iph.daddr) {
 173                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 174                                 return t;
 175                 }
 176         }
 177         for (t = tunnels_l[h1]; t; t = t->next) {
 178                 if (local == t->parms.iph.saddr ||
 179                      (local == t->parms.iph.daddr &&
 180                       ipv4_is_multicast(local))) {
 181                         if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 182                                 return t;
 183                 }
 184         }
 185         for (t = tunnels_wc[h1]; t; t = t->next) {
 186                 if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
 187                         return t;
 188         }
 189
 190         if (ipgre_fb_tunnel_dev->flags&IFF_UP)
 191                 return netdev_priv(ipgre_fb_tunnel_dev);
 192         return NULL;
 193 }
 194
 195 static struct ip_tunnel **__ipgre_bucket(struct ip_tunnel_parm *parms)
 196 {
 197         __be32 remote = parms->iph.daddr;
 198         __be32 local = parms->iph.saddr;
 199         __be32 key = parms->i_key;
 200         unsigned h = HASH(key);
 201         int prio = 0;
 202
 203         if (local)
 204                 prio |= 1;
 205         if (remote && !ipv4_is_multicast(remote)) {
 206                 prio |= 2;
 207                 h ^= HASH(remote);
 208         }
 209
 210         return &tunnels[prio][h];
 211 }
 212
 213 static inline struct ip_tunnel **ipgre_bucket(struct ip_tunnel *t)
 214 {
 215         return __ipgre_bucket(&t->parms);
 216 }
 217
 218 static void ipgre_tunnel_link(struct ip_tunnel *t)
 219 {
 220         struct ip_tunnel **tp = ipgre_bucket(t);
 221
 222         t->next = *tp;
 223         write_lock_bh(&ipgre_lock);
 224         *tp = t;
 225         write_unlock_bh(&ipgre_lock);
 226 }
 227
 228 static void ipgre_tunnel_unlink(struct ip_tunnel *t)
 229 {
 230         struct ip_tunnel **tp;
 231
 232         for (tp = ipgre_bucket(t); *tp; tp = &(*tp)->next) {
 233                 if (t == *tp) {
 234                         write_lock_bh(&ipgre_lock);
 235                         *tp = t->next;
 236                         write_unlock_bh(&ipgre_lock);
 237                         break;
 238                 }
 239         }
 240 }
 241
 242 static struct ip_tunnel * ipgre_tunnel_locate(struct ip_tunnel_parm *parms, int create)
 243 {
 244         __be32 remote = parms->iph.daddr;
 245         __be32 local = parms->iph.saddr;
 246         __be32 key = parms->i_key;
 247         struct ip_tunnel *t, **tp, *nt;
 248         struct net_device *dev;
 249         char name[IFNAMSIZ];
 250
 251         for (tp = __ipgre_bucket(parms); (t = *tp) != NULL; tp = &t->next) {
 252                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
 253                         if (key == t->parms.i_key)
 254                                 return t;
 255                 }
 256         }
 257         if (!create)
 258                 return NULL;
 259
 260         if (parms->name[0])
 261                 strlcpy(name, parms->name, IFNAMSIZ);
 262         else
 263                 sprintf(name, "gre%%d");
 264
 265         dev = alloc_netdev(sizeof(*t), name, ipgre_tunnel_setup);
 266         if (!dev)
 267           return NULL;
 268
 269         if (strchr(name, '%')) {
 270                 if (dev_alloc_name(dev, name) < 0)
 271                         goto failed_free;
 272         }
 273
 274         dev->init = ipgre_tunnel_init;
 275         nt = netdev_priv(dev);
 276         nt->parms = *parms;
 277
 278         if (register_netdevice(dev) < 0)
 279                 goto failed_free;
 280
 281         dev_hold(dev);
 282         ipgre_tunnel_link(nt);
 283         return nt;
 284
 285 failed_free:
 286         free_netdev(dev);
 287         return NULL;
 288 }
 289
 290 static void ipgre_tunnel_uninit(struct net_device *dev)
 291 {
 292         ipgre_tunnel_unlink(netdev_priv(dev));
 293         dev_put(dev);
 294 }
 295
 296
 297 static void ipgre_err(struct sk_buff *skb, u32 info)
 298 {
 299 #ifndef I_WISH_WORLD_WERE_PERFECT
 300
 301 /* It is not :-( All the routers (except for Linux) return only
 302    8 bytes of packet payload. It means, that precise relaying of
 303    ICMP in the real Internet is absolutely infeasible.
 304
 305    Moreover, Cisco "wise men" put GRE key to the third word
 306    in GRE header. It makes impossible maintaining even soft state for keyed
 307    GRE tunnels with enabled checksum. Tell them "thank you".
 308
 309    Well, I wonder, rfc1812 was written by Cisco employee,
 310    what the hell these idiots break standrads established
 311    by themself???
 312  */
 313
 314         struct iphdr *iph = (struct iphdr*)skb->data;
 315         __be16       *p = (__be16*)(skb->data+(iph->ihl<<2));
 316         int grehlen = (iph->ihl<<2) + 4;
 317         const int type = icmp_hdr(skb)->type;
 318         const int code = icmp_hdr(skb)->code;
 319         struct ip_tunnel *t;
 320         __be16 flags;
 321
 322         flags = p[0];
 323         if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
 324                 if (flags&(GRE_VERSION|GRE_ROUTING))
 325                         return;
 326                 if (flags&GRE_KEY) {
 327                         grehlen += 4;
 328                         if (flags&GRE_CSUM)
 329                                 grehlen += 4;
 330                 }
 331         }
 332
 333         /* If only 8 bytes returned, keyed message will be dropped here */
 334         if (skb_headlen(skb) < grehlen)
 335                 return;
 336
 337         switch (type) {
 338         default:
 339         case ICMP_PARAMETERPROB:
 340                 return;
 341
 342         case ICMP_DEST_UNREACH:
 343                 switch (code) {
 344                 case ICMP_SR_FAILED:
 345                 case ICMP_PORT_UNREACH:
 346                         /* Impossible event. */
 347                         return;
 348                 case ICMP_FRAG_NEEDED:
 349                         /* Soft state for pmtu is maintained by IP core. */
 350                         return;
 351                 default:
 352                         /* All others are translated to HOST_UNREACH.
 353                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 354                            I believe they are just ether pollution. --ANK
 355                          */
 356                         break;
 357                 }
 358                 break;
 359         case ICMP_TIME_EXCEEDED:
 360                 if (code != ICMP_EXC_TTL)
 361                         return;
 362                 break;
 363         }
 364
 365         read_lock(&ipgre_lock);
 366         t = ipgre_tunnel_lookup(iph->daddr, iph->saddr, (flags&GRE_KEY) ? *(((__be32*)p) + (grehlen>>2) - 1) : 0);
 367         if (t == NULL || t->parms.iph.daddr == 0 ||
 368             ipv4_is_multicast(t->parms.iph.daddr))
 369                 goto out;
 370
 371         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 372                 goto out;
 373
 374         if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
 375                 t->err_count++;
 376         else
 377                 t->err_count = 1;
 378         t->err_time = jiffies;
 379 out:
 380         read_unlock(&ipgre_lock);
 381         return;
 382 #else
 383         struct iphdr *iph = (struct iphdr*)dp;
 384         struct iphdr *eiph;
 385         __be16       *p = (__be16*)(dp+(iph->ihl<<2));
 386         const int type = icmp_hdr(skb)->type;
 387         const int code = icmp_hdr(skb)->code;
 388         int rel_type = 0;
 389         int rel_code = 0;
 390         __be32 rel_info = 0;
 391         __u32 n = 0;
 392         __be16 flags;
 393         int grehlen = (iph->ihl<<2) + 4;
 394         struct sk_buff *skb2;
 395         struct flowi fl;
 396         struct rtable *rt;
 397
 398         if (p[1] != htons(ETH_P_IP))
 399                 return;
 400
 401         flags = p[0];
 402         if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
 403                 if (flags&(GRE_VERSION|GRE_ROUTING))
 404                         return;
 405                 if (flags&GRE_CSUM)
 406                         grehlen += 4;
 407                 if (flags&GRE_KEY)
 408                         grehlen += 4;
 409                 if (flags&GRE_SEQ)
 410                         grehlen += 4;
 411         }
 412         if (len < grehlen + sizeof(struct iphdr))
 413                 return;
 414         eiph = (struct iphdr*)(dp + grehlen);
 415
 416         switch (type) {
 417         default:
 418                 return;
 419         case ICMP_PARAMETERPROB:
 420                 n = ntohl(icmp_hdr(skb)->un.gateway) >> 24;
 421                 if (n < (iph->ihl<<2))
 422                         return;
 423
 424                 /* So... This guy found something strange INSIDE encapsulated
 425                    packet. Well, he is fool, but what can we do ?
 426                  */
 427                 rel_type = ICMP_PARAMETERPROB;
 428                 n -= grehlen;
 429                 rel_info = htonl(n << 24);
 430                 break;
 431
 432         case ICMP_DEST_UNREACH:
 433                 switch (code) {
 434                 case ICMP_SR_FAILED:
 435                 case ICMP_PORT_UNREACH:
 436                         /* Impossible event. */
 437                         return;
 438                 case ICMP_FRAG_NEEDED:
 439                         /* And it is the only really necessary thing :-) */
 440                         n = ntohs(icmp_hdr(skb)->un.frag.mtu);
 441                         if (n < grehlen+68)
 442                                 return;
 443                         n -= grehlen;
 444                         /* BSD 4.2 MORE DOES NOT EXIST IN NATURE. */
 445                         if (n > ntohs(eiph->tot_len))
 446                                 return;
 447                         rel_info = htonl(n);
 448                         break;
 449                 default:
 450                         /* All others are translated to HOST_UNREACH.
 451                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 452                            I believe, it is just ether pollution. --ANK
 453                          */
 454                         rel_type = ICMP_DEST_UNREACH;
 455                         rel_code = ICMP_HOST_UNREACH;
 456                         break;
 457                 }
 458                 break;
 459         case ICMP_TIME_EXCEEDED:
 460                 if (code != ICMP_EXC_TTL)
 461                         return;
 462                 break;
 463         }
 464
 465         /* Prepare fake skb to feed it to icmp_send */
 466         skb2 = skb_clone(skb, GFP_ATOMIC);
 467         if (skb2 == NULL)
 468                 return;
 469         dst_release(skb2->dst);
 470         skb2->dst = NULL;
 471         skb_pull(skb2, skb->data - (u8*)eiph);
 472         skb_reset_network_header(skb2);
 473
 474         /* Try to guess incoming interface */
 475         memset(&fl, 0, sizeof(fl));
 476         fl.fl4_dst = eiph->saddr;
 477         fl.fl4_tos = RT_TOS(eiph->tos);
 478         fl.proto = IPPROTO_GRE;
 479         if (ip_route_output_key(&init_net, &rt, &fl)) {
 480                 kfree_skb(skb2);
 481                 return;
 482         }
 483         skb2->dev = rt->u.dst.dev;
 484
 485         /* route "incoming" packet */
 486         if (rt->rt_flags&RTCF_LOCAL) {
 487                 ip_rt_put(rt);
 488                 rt = NULL;
 489                 fl.fl4_dst = eiph->daddr;
 490                 fl.fl4_src = eiph->saddr;
 491                 fl.fl4_tos = eiph->tos;
 492                 if (ip_route_output_key(&init_net, &rt, &fl) ||
 493                     rt->u.dst.dev->type != ARPHRD_IPGRE) {
 494                         ip_rt_put(rt);
 495                         kfree_skb(skb2);
 496                         return;
 497                 }
 498         } else {
 499                 ip_rt_put(rt);
 500                 if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos, skb2->dev) ||
 501                     skb2->dst->dev->type != ARPHRD_IPGRE) {
 502                         kfree_skb(skb2);
 503                         return;
 504                 }
 505         }
 506
 507         /* change mtu on this route */
 508         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
 509                 if (n > dst_mtu(skb2->dst)) {
 510                         kfree_skb(skb2);
 511                         return;
 512                 }
 513                 skb2->dst->ops->update_pmtu(skb2->dst, n);
 514         } else if (type == ICMP_TIME_EXCEEDED) {
 515                 struct ip_tunnel *t = netdev_priv(skb2->dev);
 516                 if (t->parms.iph.ttl) {
 517                         rel_type = ICMP_DEST_UNREACH;
 518                         rel_code = ICMP_HOST_UNREACH;
 519                 }
 520         }
 521
 522         icmp_send(skb2, rel_type, rel_code, rel_info);
 523         kfree_skb(skb2);
 524 #endif
 525 }
 526
 527 static inline void ipgre_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
 528 {
 529         if (INET_ECN_is_ce(iph->tos)) {
 530                 if (skb->protocol == htons(ETH_P_IP)) {
 531                         IP_ECN_set_ce(ip_hdr(skb));
 532                 } else if (skb->protocol == htons(ETH_P_IPV6)) {
 533                         IP6_ECN_set_ce(ipv6_hdr(skb));
 534                 }
 535         }
 536 }
 537
 538 static inline u8
 539 ipgre_ecn_encapsulate(u8 tos, struct iphdr *old_iph, struct sk_buff *skb)
 540 {
 541         u8 inner = 0;
 542         if (skb->protocol == htons(ETH_P_IP))
 543                 inner = old_iph->tos;
 544         else if (skb->protocol == htons(ETH_P_IPV6))
 545                 inner = ipv6_get_dsfield((struct ipv6hdr *)old_iph);
 546         return INET_ECN_encapsulate(tos, inner);
 547 }
 548
 549 static int ipgre_rcv(struct sk_buff *skb)
 550 {
 551         struct iphdr *iph;
 552         u8     *h;
 553         __be16    flags;
 554         __sum16   csum = 0;
 555         __be32 key = 0;
 556         u32    seqno = 0;
 557         struct ip_tunnel *tunnel;
 558         int    offset = 4;
 559
 560         if (!pskb_may_pull(skb, 16))
 561                 goto drop_nolock;
 562
 563         iph = ip_hdr(skb);
 564         h = skb->data;
 565         flags = *(__be16*)h;
 566
 567         if (flags&(GRE_CSUM|GRE_KEY|GRE_ROUTING|GRE_SEQ|GRE_VERSION)) {
 568                 /* - Version must be 0.
 569                    - We do not support routing headers.
 570                  */
 571                 if (flags&(GRE_VERSION|GRE_ROUTING))
 572                         goto drop_nolock;
 573
 574                 if (flags&GRE_CSUM) {
 575                         switch (skb->ip_summed) {
 576                         case CHECKSUM_COMPLETE:
 577                                 csum = csum_fold(skb->csum);
 578                                 if (!csum)
 579                                         break;
 580                                 /* fall through */
 581                         case CHECKSUM_NONE:
 582                                 skb->csum = 0;
 583                                 csum = __skb_checksum_complete(skb);
 584                                 skb->ip_summed = CHECKSUM_COMPLETE;
 585                         }
 586                         offset += 4;
 587                 }
 588                 if (flags&GRE_KEY) {
 589                         key = *(__be32*)(h + offset);
 590                         offset += 4;
 591                 }
 592                 if (flags&GRE_SEQ) {
 593                         seqno = ntohl(*(__be32*)(h + offset));
 594                         offset += 4;
 595                 }
 596         }
 597
 598         read_lock(&ipgre_lock);
 599         if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) {
 600                 secpath_reset(skb);
 601
 602                 skb->protocol = *(__be16*)(h + 2);
 603                 /* WCCP version 1 and 2 protocol decoding.
 604                  * - Change protocol to IP
 605                  * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
 606                  */
 607                 if (flags == 0 &&
 608                     skb->protocol == htons(ETH_P_WCCP)) {
 609                         skb->protocol = htons(ETH_P_IP);
 610                         if ((*(h + offset) & 0xF0) != 0x40)
 611                                 offset += 4;
 612                 }
 613
 614                 skb->mac_header = skb->network_header;
 615                 __pskb_pull(skb, offset);
 616                 skb_reset_network_header(skb);
 617                 skb_postpull_rcsum(skb, skb_transport_header(skb), offset);
 618                 skb->pkt_type = PACKET_HOST;
 619 #ifdef CONFIG_NET_IPGRE_BROADCAST
 620                 if (ipv4_is_multicast(iph->daddr)) {
 621                         /* Looped back packet, drop it! */
 622                         if (((struct rtable*)skb->dst)->fl.iif == 0)
 623                                 goto drop;
 624                         tunnel->stat.multicast++;
 625                         skb->pkt_type = PACKET_BROADCAST;
 626                 }
 627 #endif
 628
 629                 if (((flags&GRE_CSUM) && csum) ||
 630                     (!(flags&GRE_CSUM) && tunnel->parms.i_flags&GRE_CSUM)) {
 631                         tunnel->stat.rx_crc_errors++;
 632                         tunnel->stat.rx_errors++;
 633                         goto drop;
 634                 }
 635                 if (tunnel->parms.i_flags&GRE_SEQ) {
 636                         if (!(flags&GRE_SEQ) ||
 637                             (tunnel->i_seqno && (s32)(seqno - tunnel->i_seqno) < 0)) {
 638                                 tunnel->stat.rx_fifo_errors++;
 639                                 tunnel->stat.rx_errors++;
 640                                 goto drop;
 641                         }
 642                         tunnel->i_seqno = seqno + 1;
 643                 }
 644                 tunnel->stat.rx_packets++;
 645                 tunnel->stat.rx_bytes += skb->len;
 646                 skb->dev = tunnel->dev;
 647                 dst_release(skb->dst);
 648                 skb->dst = NULL;
 649                 nf_reset(skb);
 650                 ipgre_ecn_decapsulate(iph, skb);
 651                 netif_rx(skb);
 652                 read_unlock(&ipgre_lock);
 653                 return(0);
 654         }
 655         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 656
 657 drop:
 658         read_unlock(&ipgre_lock);
 659 drop_nolock:
 660         kfree_skb(skb);
 661         return(0);
 662 }
 663
 664 static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 665 {
 666         struct ip_tunnel *tunnel = netdev_priv(dev);
 667         struct net_device_stats *stats = &tunnel->stat;
 668         struct iphdr  *old_iph = ip_hdr(skb);
 669         struct iphdr  *tiph;
 670         u8     tos;
 671         __be16 df;
 672         struct rtable *rt;                      /* Route to the other host */
 673         struct net_device *tdev;                        /* Device to other host */
 674         struct iphdr  *iph;                     /* Our new IP header */
 675         unsigned int max_headroom;              /* The extra header space needed */
 676         int    gre_hlen;
 677         __be32 dst;
 678         int    mtu;
 679
 680         if (tunnel->recursion++) {
 681                 tunnel->stat.collisions++;
 682                 goto tx_error;
 683         }
 684
 685         if (dev->header_ops) {
 686                 gre_hlen = 0;
 687                 tiph = (struct iphdr*)skb->data;
 688         } else {
 689                 gre_hlen = tunnel->hlen;
 690                 tiph = &tunnel->parms.iph;
 691         }
 692
 693         if ((dst = tiph->daddr) == 0) {
 694                 /* NBMA tunnel */
 695
 696                 if (skb->dst == NULL) {
 697                         tunnel->stat.tx_fifo_errors++;
 698                         goto tx_error;
 699                 }
 700
 701                 if (skb->protocol == htons(ETH_P_IP)) {
 702                         rt = (struct rtable*)skb->dst;
 703                         if ((dst = rt->rt_gateway) == 0)
 704                                 goto tx_error_icmp;
 705                 }
 706 #ifdef CONFIG_IPV6
 707                 else if (skb->protocol == htons(ETH_P_IPV6)) {
 708                         struct in6_addr *addr6;
 709                         int addr_type;
 710                         struct neighbour *neigh = skb->dst->neighbour;
 711
 712                         if (neigh == NULL)
 713                                 goto tx_error;
 714
 715                         addr6 = (struct in6_addr*)&neigh->primary_key;
 716                         addr_type = ipv6_addr_type(addr6);
 717
 718                         if (addr_type == IPV6_ADDR_ANY) {
 719                                 addr6 = &ipv6_hdr(skb)->daddr;
 720                                 addr_type = ipv6_addr_type(addr6);
 721                         }
 722
 723                         if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
 724                                 goto tx_error_icmp;
 725
 726                         dst = addr6->s6_addr32[3];
 727                 }
 728 #endif
 729                 else
 730                         goto tx_error;
 731         }
 732
 733         tos = tiph->tos;
 734         if (tos&1) {
 735                 if (skb->protocol == htons(ETH_P_IP))
 736                         tos = old_iph->tos;
 737                 tos &= ~1;
 738         }
 739
 740         {
 741                 struct flowi fl = { .oif = tunnel->parms.link,
 742                                     .nl_u = { .ip4_u =
 743                                               { .daddr = dst,
 744                                                 .saddr = tiph->saddr,
 745                                                 .tos = RT_TOS(tos) } },
 746                                     .proto = IPPROTO_GRE };
 747                 if (ip_route_output_key(&init_net, &rt, &fl)) {
 748                         tunnel->stat.tx_carrier_errors++;
 749                         goto tx_error;
 750                 }
 751         }
 752         tdev = rt->u.dst.dev;
 753
 754         if (tdev == dev) {
 755                 ip_rt_put(rt);
 756                 tunnel->stat.collisions++;
 757                 goto tx_error;
 758         }
 759
 760         df = tiph->frag_off;
 761         if (df)
 762                 mtu = dst_mtu(&rt->u.dst) - tunnel->hlen;
 763         else
 764                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 765
 766         if (skb->dst)
 767                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 768
 769         if (skb->protocol == htons(ETH_P_IP)) {
 770                 df |= (old_iph->frag_off&htons(IP_DF));
 771
 772                 if ((old_iph->frag_off&htons(IP_DF)) &&
 773                     mtu < ntohs(old_iph->tot_len)) {
 774                         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
 775                         ip_rt_put(rt);
 776                         goto tx_error;
 777                 }
 778         }
 779 #ifdef CONFIG_IPV6
 780         else if (skb->protocol == htons(ETH_P_IPV6)) {
 781                 struct rt6_info *rt6 = (struct rt6_info*)skb->dst;
 782
 783                 if (rt6 && mtu < dst_mtu(skb->dst) && mtu >= IPV6_MIN_MTU) {
 784                         if ((tunnel->parms.iph.daddr &&
 785                              !ipv4_is_multicast(tunnel->parms.iph.daddr)) ||
 786                             rt6->rt6i_dst.plen == 128) {
 787                                 rt6->rt6i_flags |= RTF_MODIFIED;
 788                                 skb->dst->metrics[RTAX_MTU-1] = mtu;
 789                         }
 790                 }
 791
 792                 if (mtu >= IPV6_MIN_MTU && mtu < skb->len - tunnel->hlen + gre_hlen) {
 793                         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
 794                         ip_rt_put(rt);
 795                         goto tx_error;
 796                 }
 797         }
 798 #endif
 799
 800         if (tunnel->err_count > 0) {
 801                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 802                         tunnel->err_count--;
 803
 804                         dst_link_failure(skb);
 805                 } else
 806                         tunnel->err_count = 0;
 807         }
 808
 809         max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen;
 810
 811         if (skb_headroom(skb) < max_headroom || skb_shared(skb)||
 812             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
 813                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 814                 if (!new_skb) {
 815                         ip_rt_put(rt);
 816                         stats->tx_dropped++;
 817                         dev_kfree_skb(skb);
 818                         tunnel->recursion--;
 819                         return 0;
 820                 }
 821                 if (skb->sk)
 822                         skb_set_owner_w(new_skb, skb->sk);
 823                 dev_kfree_skb(skb);
 824                 skb = new_skb;
 825                 old_iph = ip_hdr(skb);
 826         }
 827
 828         skb->transport_header = skb->network_header;
 829         skb_push(skb, gre_hlen);
 830         skb_reset_network_header(skb);
 831         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 832         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
 833                               IPSKB_REROUTED);
 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                     =       ip_hdr(skb);
 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         ((__be16*)(iph+1))[0] = tunnel->parms.o_flags;
 862         ((__be16*)(iph+1))[1] = skb->protocol;
 863
 864         if (tunnel->parms.o_flags&(GRE_KEY|GRE_CSUM|GRE_SEQ)) {
 865                 __be32 *ptr = (__be32*)(((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                         *(__sum16*)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 void ipgre_tunnel_bind_dev(struct net_device *dev)
 899 {
 900         struct net_device *tdev = NULL;
 901         struct ip_tunnel *tunnel;
 902         struct iphdr *iph;
 903         int hlen = LL_MAX_HEADER;
 904         int mtu = ETH_DATA_LEN;
 905         int addend = sizeof(struct iphdr) + 4;
 906
 907         tunnel = netdev_priv(dev);
 908         iph = &tunnel->parms.iph;
 909
 910         /* Guess output device to choose reasonable mtu and hard_header_len */
 911
 912         if (iph->daddr) {
 913                 struct flowi fl = { .oif = tunnel->parms.link,
 914                                     .nl_u = { .ip4_u =
 915                                               { .daddr = iph->daddr,
 916                                                 .saddr = iph->saddr,
 917                                                 .tos = RT_TOS(iph->tos) } },
 918                                     .proto = IPPROTO_GRE };
 919                 struct rtable *rt;
 920                 if (!ip_route_output_key(&init_net, &rt, &fl)) {
 921                         tdev = rt->u.dst.dev;
 922                         ip_rt_put(rt);
 923                 }
 924                 dev->flags |= IFF_POINTOPOINT;
 925         }
 926
 927         if (!tdev && tunnel->parms.link)
 928                 tdev = __dev_get_by_index(&init_net, tunnel->parms.link);
 929
 930         if (tdev) {
 931                 hlen = tdev->hard_header_len;
 932                 mtu = tdev->mtu;
 933         }
 934         dev->iflink = tunnel->parms.link;
 935
 936         /* Precalculate GRE options length */
 937         if (tunnel->parms.o_flags&(GRE_CSUM|GRE_KEY|GRE_SEQ)) {
 938                 if (tunnel->parms.o_flags&GRE_CSUM)
 939                         addend += 4;
 940                 if (tunnel->parms.o_flags&GRE_KEY)
 941                         addend += 4;
 942                 if (tunnel->parms.o_flags&GRE_SEQ)
 943                         addend += 4;
 944         }
 945         dev->hard_header_len = hlen + addend;
 946         dev->mtu = mtu - addend;
 947         tunnel->hlen = addend;
 948
 949 }
 950
 951 static int
 952 ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 953 {
 954         int err = 0;
 955         struct ip_tunnel_parm p;
 956         struct ip_tunnel *t;
 957
 958         switch (cmd) {
 959         case SIOCGETTUNNEL:
 960                 t = NULL;
 961                 if (dev == ipgre_fb_tunnel_dev) {
 962                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 963                                 err = -EFAULT;
 964                                 break;
 965                         }
 966                         t = ipgre_tunnel_locate(&p, 0);
 967                 }
 968                 if (t == NULL)
 969                         t = netdev_priv(dev);
 970                 memcpy(&p, &t->parms, sizeof(p));
 971                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 972                         err = -EFAULT;
 973                 break;
 974
 975         case SIOCADDTUNNEL:
 976         case SIOCCHGTUNNEL:
 977                 err = -EPERM;
 978                 if (!capable(CAP_NET_ADMIN))
 979                         goto done;
 980
 981                 err = -EFAULT;
 982                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 983                         goto done;
 984
 985                 err = -EINVAL;
 986                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_GRE ||
 987                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)) ||
 988                     ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING)))
 989                         goto done;
 990                 if (p.iph.ttl)
 991                         p.iph.frag_off |= htons(IP_DF);
 992
 993                 if (!(p.i_flags&GRE_KEY))
 994                         p.i_key = 0;
 995                 if (!(p.o_flags&GRE_KEY))
 996                         p.o_key = 0;
 997
 998                 t = ipgre_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 999
1000                 if (dev != ipgre_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
1001                         if (t != NULL) {
1002                                 if (t->dev != dev) {
1003                                         err = -EEXIST;
1004                                         break;
1005                                 }
1006                         } else {
1007                                 unsigned nflags=0;
1008
1009                                 t = netdev_priv(dev);
1010
1011                                 if (ipv4_is_multicast(p.iph.daddr))
1012                                         nflags = IFF_BROADCAST;
1013                                 else if (p.iph.daddr)
1014                                         nflags = IFF_POINTOPOINT;
1015
1016                                 if ((dev->flags^nflags)&(IFF_POINTOPOINT|IFF_BROADCAST)) {
1017                                         err = -EINVAL;
1018                                         break;
1019                                 }
1020                                 ipgre_tunnel_unlink(t);
1021                                 t->parms.iph.saddr = p.iph.saddr;
1022                                 t->parms.iph.daddr = p.iph.daddr;
1023                                 t->parms.i_key = p.i_key;
1024                                 t->parms.o_key = p.o_key;
1025                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
1026                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
1027                                 ipgre_tunnel_link(t);
1028                                 netdev_state_change(dev);
1029                         }
1030                 }
1031
1032                 if (t) {
1033                         err = 0;
1034                         if (cmd == SIOCCHGTUNNEL) {
1035                                 t->parms.iph.ttl = p.iph.ttl;
1036                                 t->parms.iph.tos = p.iph.tos;
1037                                 t->parms.iph.frag_off = p.iph.frag_off;
1038                                 if (t->parms.link != p.link) {
1039                                         t->parms.link = p.link;
1040                                         ipgre_tunnel_bind_dev(dev);
1041                                         netdev_state_change(dev);
1042                                 }
1043                         }
1044                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
1045                                 err = -EFAULT;
1046                 } else
1047                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
1048                 break;
1049
1050         case SIOCDELTUNNEL:
1051                 err = -EPERM;
1052                 if (!capable(CAP_NET_ADMIN))
1053                         goto done;
1054
1055                 if (dev == ipgre_fb_tunnel_dev) {
1056                         err = -EFAULT;
1057                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
1058                                 goto done;
1059                         err = -ENOENT;
1060                         if ((t = ipgre_tunnel_locate(&p, 0)) == NULL)
1061                                 goto done;
1062                         err = -EPERM;
1063                         if (t == netdev_priv(ipgre_fb_tunnel_dev))
1064                                 goto done;
1065                         dev = t->dev;
1066                 }
1067                 unregister_netdevice(dev);
1068                 err = 0;
1069                 break;
1070
1071         default:
1072                 err = -EINVAL;
1073         }
1074
1075 done:
1076         return err;
1077 }
1078
1079 static struct net_device_stats *ipgre_tunnel_get_stats(struct net_device *dev)
1080 {
1081         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
1082 }
1083
1084 static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1085 {
1086         struct ip_tunnel *tunnel = netdev_priv(dev);
1087         if (new_mtu < 68 || new_mtu > 0xFFF8 - tunnel->hlen)
1088                 return -EINVAL;
1089         dev->mtu = new_mtu;
1090         return 0;
1091 }
1092
1093 /* Nice toy. Unfortunately, useless in real life :-)
1094    It allows to construct virtual multiprotocol broadcast "LAN"
1095    over the Internet, provided multicast routing is tuned.
1096
1097
1098    I have no idea was this bicycle invented before me,
1099    so that I had to set ARPHRD_IPGRE to a random value.
1100    I have an impression, that Cisco could make something similar,
1101    but this feature is apparently missing in IOS<=11.2(8).
1102
1103    I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks
1104    with broadcast 224.66.66.66. If you have access to mbone, play with me :-)
1105
1106    ping -t 255 224.66.66.66
1107
1108    If nobody answers, mbone does not work.
1109
1110    ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255
1111    ip addr add 10.66.66.<somewhat>/24 dev Universe
1112    ifconfig Universe up
1113    ifconfig Universe add fe80::<Your_real_addr>/10
1114    ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96
1115    ftp 10.66.66.66
1116    ...
1117    ftp fec0:6666:6666::193.233.7.65
1118    ...
1119
1120  */
1121
1122 static int ipgre_header(struct sk_buff *skb, struct net_device *dev,
1123                         unsigned short type,
1124                         const void *daddr, const void *saddr, unsigned len)
1125 {
1126         struct ip_tunnel *t = netdev_priv(dev);
1127         struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen);
1128         __be16 *p = (__be16*)(iph+1);
1129
1130         memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
1131         p[0]            = t->parms.o_flags;
1132         p[1]            = htons(type);
1133
1134         /*
1135          *      Set the source hardware address.
1136          */
1137
1138         if (saddr)
1139                 memcpy(&iph->saddr, saddr, 4);
1140
1141         if (daddr) {
1142                 memcpy(&iph->daddr, daddr, 4);
1143                 return t->hlen;
1144         }
1145         if (iph->daddr && !ipv4_is_multicast(iph->daddr))
1146                 return t->hlen;
1147
1148         return -t->hlen;
1149 }
1150
1151 static int ipgre_header_parse(const struct sk_buff *skb, unsigned char *haddr)
1152 {
1153         struct iphdr *iph = (struct iphdr*) skb_mac_header(skb);
1154         memcpy(haddr, &iph->saddr, 4);
1155         return 4;
1156 }
1157
1158 static const struct header_ops ipgre_header_ops = {
1159         .create = ipgre_header,
1160         .parse  = ipgre_header_parse,
1161 };
1162
1163 #ifdef CONFIG_NET_IPGRE_BROADCAST
1164 static int ipgre_open(struct net_device *dev)
1165 {
1166         struct ip_tunnel *t = netdev_priv(dev);
1167
1168         if (ipv4_is_multicast(t->parms.iph.daddr)) {
1169                 struct flowi fl = { .oif = t->parms.link,
1170                                     .nl_u = { .ip4_u =
1171                                               { .daddr = t->parms.iph.daddr,
1172                                                 .saddr = t->parms.iph.saddr,
1173                                                 .tos = RT_TOS(t->parms.iph.tos) } },
1174                                     .proto = IPPROTO_GRE };
1175                 struct rtable *rt;
1176                 if (ip_route_output_key(&init_net, &rt, &fl))
1177                         return -EADDRNOTAVAIL;
1178                 dev = rt->u.dst.dev;
1179                 ip_rt_put(rt);
1180                 if (__in_dev_get_rtnl(dev) == NULL)
1181                         return -EADDRNOTAVAIL;
1182                 t->mlink = dev->ifindex;
1183                 ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);
1184         }
1185         return 0;
1186 }
1187
1188 static int ipgre_close(struct net_device *dev)
1189 {
1190         struct ip_tunnel *t = netdev_priv(dev);
1191         if (ipv4_is_multicast(t->parms.iph.daddr) && t->mlink) {
1192                 struct in_device *in_dev;
1193                 in_dev = inetdev_by_index(dev->nd_net, t->mlink);
1194                 if (in_dev) {
1195                         ip_mc_dec_group(in_dev, t->parms.iph.daddr);
1196                         in_dev_put(in_dev);
1197                 }
1198         }
1199         return 0;
1200 }
1201
1202 #endif
1203
1204 static void ipgre_tunnel_setup(struct net_device *dev)
1205 {
1206         dev->uninit             = ipgre_tunnel_uninit;
1207         dev->destructor         = free_netdev;
1208         dev->hard_start_xmit    = ipgre_tunnel_xmit;
1209         dev->get_stats          = ipgre_tunnel_get_stats;
1210         dev->do_ioctl           = ipgre_tunnel_ioctl;
1211         dev->change_mtu         = ipgre_tunnel_change_mtu;
1212
1213         dev->type               = ARPHRD_IPGRE;
1214         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr) + 4;
1215         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr) - 4;
1216         dev->flags              = IFF_NOARP;
1217         dev->iflink             = 0;
1218         dev->addr_len           = 4;
1219 }
1220
1221 static int ipgre_tunnel_init(struct net_device *dev)
1222 {
1223         struct ip_tunnel *tunnel;
1224         struct iphdr *iph;
1225
1226         tunnel = netdev_priv(dev);
1227         iph = &tunnel->parms.iph;
1228
1229         tunnel->dev = dev;
1230         strcpy(tunnel->parms.name, dev->name);
1231
1232         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1233         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1234
1235         ipgre_tunnel_bind_dev(dev);
1236
1237         if (iph->daddr) {
1238 #ifdef CONFIG_NET_IPGRE_BROADCAST
1239                 if (ipv4_is_multicast(iph->daddr)) {
1240                         if (!iph->saddr)
1241                                 return -EINVAL;
1242                         dev->flags = IFF_BROADCAST;
1243                         dev->header_ops = &ipgre_header_ops;
1244                         dev->open = ipgre_open;
1245                         dev->stop = ipgre_close;
1246                 }
1247 #endif
1248         } else
1249                 dev->header_ops = &ipgre_header_ops;
1250
1251         return 0;
1252 }
1253
1254 static int __init ipgre_fb_tunnel_init(struct net_device *dev)
1255 {
1256         struct ip_tunnel *tunnel = netdev_priv(dev);
1257         struct iphdr *iph = &tunnel->parms.iph;
1258
1259         tunnel->dev = dev;
1260         strcpy(tunnel->parms.name, dev->name);
1261
1262         iph->version            = 4;
1263         iph->protocol           = IPPROTO_GRE;
1264         iph->ihl                = 5;
1265         tunnel->hlen            = sizeof(struct iphdr) + 4;
1266
1267         dev_hold(dev);
1268         tunnels_wc[0]           = tunnel;
1269         return 0;
1270 }
1271
1272
1273 static struct net_protocol ipgre_protocol = {
1274         .handler        =       ipgre_rcv,
1275         .err_handler    =       ipgre_err,
1276 };
1277
1278
1279 /*
1280  *      And now the modules code and kernel interface.
1281  */
1282
1283 static int __init ipgre_init(void)
1284 {
1285         int err;
1286
1287         printk(KERN_INFO "GRE over IPv4 tunneling driver\n");
1288
1289         if (inet_add_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) {
1290                 printk(KERN_INFO "ipgre init: can't add protocol\n");
1291                 return -EAGAIN;
1292         }
1293
1294         ipgre_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0",
1295                                            ipgre_tunnel_setup);
1296         if (!ipgre_fb_tunnel_dev) {
1297                 err = -ENOMEM;
1298                 goto err1;
1299         }
1300
1301         ipgre_fb_tunnel_dev->init = ipgre_fb_tunnel_init;
1302
1303         if ((err = register_netdev(ipgre_fb_tunnel_dev)))
1304                 goto err2;
1305 out:
1306         return err;
1307 err2:
1308         free_netdev(ipgre_fb_tunnel_dev);
1309 err1:
1310         inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
1311         goto out;
1312 }
1313
1314 static void __exit ipgre_destroy_tunnels(void)
1315 {
1316         int prio;
1317
1318         for (prio = 0; prio < 4; prio++) {
1319                 int h;
1320                 for (h = 0; h < HASH_SIZE; h++) {
1321                         struct ip_tunnel *t;
1322                         while ((t = tunnels[prio][h]) != NULL)
1323                                 unregister_netdevice(t->dev);
1324                 }
1325         }
1326 }
1327
1328 static void __exit ipgre_fini(void)
1329 {
1330         if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0)
1331                 printk(KERN_INFO "ipgre close: can't remove protocol\n");
1332
1333         rtnl_lock();
1334         ipgre_destroy_tunnels();
1335         rtnl_unlock();
1336 }
1337
1338 module_init(ipgre_init);
1339 module_exit(ipgre_fini);
1340 MODULE_LICENSE("GPL");