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   1 /*
   2  *      Linux NET3:     IP/IP protocol decoder.
   3  *
   4  *      Version: $Id: ipip.c,v 1.50 2001/10/02 02:22:36 davem Exp $
   5  *
   6  *      Authors:
   7  *              Sam Lantinga (slouken@cs.ucdavis.edu)  02/01/95
   8  *
   9  *      Fixes:
  10  *              Alan Cox        :       Merged and made usable non modular (its so tiny its silly as
  11  *                                      a module taking up 2 pages).
  12  *              Alan Cox        :       Fixed bug with 1.3.18 and IPIP not working (now needs to set skb->h.iph)
  13  *                                      to keep ip_forward happy.
  14  *              Alan Cox        :       More fixes for 1.3.21, and firewall fix. Maybe this will work soon 8).
  15  *              Kai Schulte     :       Fixed #defines for IP_FIREWALL->FIREWALL
  16  *              David Woodhouse :       Perform some basic ICMP handling.
  17  *                                      IPIP Routing without decapsulation.
  18  *              Carlos Picoto   :       GRE over IP support
  19  *              Alexey Kuznetsov:       Reworked. Really, now it is truncated version of ipv4/ip_gre.c.
  20  *                                      I do not want to merge them together.
  21  *
  22  *      This program is free software; you can redistribute it and/or
  23  *      modify it under the terms of the GNU General Public License
  24  *      as published by the Free Software Foundation; either version
  25  *      2 of the License, or (at your option) any later version.
  26  *
  27  */
  28
  29 /* tunnel.c: an IP tunnel driver
  30
  31         The purpose of this driver is to provide an IP tunnel through
  32         which you can tunnel network traffic transparently across subnets.
  33
  34         This was written by looking at Nick Holloway's dummy driver
  35         Thanks for the great code!
  36
  37                 -Sam Lantinga   (slouken@cs.ucdavis.edu)  02/01/95
  38
  39         Minor tweaks:
  40                 Cleaned up the code a little and added some pre-1.3.0 tweaks.
  41                 dev->hard_header/hard_header_len changed to use no headers.
  42                 Comments/bracketing tweaked.
  43                 Made the tunnels use dev->name not tunnel: when error reporting.
  44                 Added tx_dropped stat
  45
  46                 -Alan Cox       (Alan.Cox@linux.org) 21 March 95
  47
  48         Reworked:
  49                 Changed to tunnel to destination gateway in addition to the
  50                         tunnel's pointopoint address
  51                 Almost completely rewritten
  52                 Note:  There is currently no firewall or ICMP handling done.
  53
  54                 -Sam Lantinga   (slouken@cs.ucdavis.edu) 02/13/96
  55
  56 */
  57
  58 /* Things I wish I had known when writing the tunnel driver:
  59
  60         When the tunnel_xmit() function is called, the skb contains the
  61         packet to be sent (plus a great deal of extra info), and dev
  62         contains the tunnel device that _we_ are.
  63
  64         When we are passed a packet, we are expected to fill in the
  65         source address with our source IP address.
  66
  67         What is the proper way to allocate, copy and free a buffer?
  68         After you allocate it, it is a "0 length" chunk of memory
  69         starting at zero.  If you want to add headers to the buffer
  70         later, you'll have to call "skb_reserve(skb, amount)" with
  71         the amount of memory you want reserved.  Then, you call
  72         "skb_put(skb, amount)" with the amount of space you want in
  73         the buffer.  skb_put() returns a pointer to the top (#0) of
  74         that buffer.  skb->len is set to the amount of space you have
  75         "allocated" with skb_put().  You can then write up to skb->len
  76         bytes to that buffer.  If you need more, you can call skb_put()
  77         again with the additional amount of space you need.  You can
  78         find out how much more space you can allocate by calling
  79         "skb_tailroom(skb)".
  80         Now, to add header space, call "skb_push(skb, header_len)".
  81         This creates space at the beginning of the buffer and returns
  82         a pointer to this new space.  If later you need to strip a
  83         header from a buffer, call "skb_pull(skb, header_len)".
  84         skb_headroom() will return how much space is left at the top
  85         of the buffer (before the main data).  Remember, this headroom
  86         space must be reserved before the skb_put() function is called.
  87         */
  88
  89 /*
  90    This version of net/ipv4/ipip.c is cloned of net/ipv4/ip_gre.c
  91
  92    For comments look at net/ipv4/ip_gre.c --ANK
  93  */
  94
  95
  96 #include <linux/capability.h>
  97 #include <linux/config.h>
  98 #include <linux/module.h>
  99 #include <linux/types.h>
 100 #include <linux/sched.h>
 101 #include <linux/kernel.h>
 102 #include <asm/uaccess.h>
 103 #include <linux/skbuff.h>
 104 #include <linux/netdevice.h>
 105 #include <linux/in.h>
 106 #include <linux/tcp.h>
 107 #include <linux/udp.h>
 108 #include <linux/if_arp.h>
 109 #include <linux/mroute.h>
 110 #include <linux/init.h>
 111 #include <linux/netfilter_ipv4.h>
 112 #include <linux/if_ether.h>
 113
 114 #include <net/sock.h>
 115 #include <net/ip.h>
 116 #include <net/icmp.h>
 117 #include <net/ipip.h>
 118 #include <net/inet_ecn.h>
 119 #include <net/xfrm.h>
 120
 121 #define HASH_SIZE  16
 122 #define HASH(addr) ((addr^(addr>>4))&0xF)
 123
 124 static int ipip_fb_tunnel_init(struct net_device *dev);
 125 static int ipip_tunnel_init(struct net_device *dev);
 126 static void ipip_tunnel_setup(struct net_device *dev);
 127
 128 static struct net_device *ipip_fb_tunnel_dev;
 129
 130 static struct ip_tunnel *tunnels_r_l[HASH_SIZE];
 131 static struct ip_tunnel *tunnels_r[HASH_SIZE];
 132 static struct ip_tunnel *tunnels_l[HASH_SIZE];
 133 static struct ip_tunnel *tunnels_wc[1];
 134 static struct ip_tunnel **tunnels[4] = { tunnels_wc, tunnels_l, tunnels_r, tunnels_r_l };
 135
 136 static DEFINE_RWLOCK(ipip_lock);
 137
 138 static struct ip_tunnel * ipip_tunnel_lookup(u32 remote, u32 local)
 139 {
 140         unsigned h0 = HASH(remote);
 141         unsigned h1 = HASH(local);
 142         struct ip_tunnel *t;
 143
 144         for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
 145                 if (local == t->parms.iph.saddr &&
 146                     remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
 147                         return t;
 148         }
 149         for (t = tunnels_r[h0]; t; t = t->next) {
 150                 if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
 151                         return t;
 152         }
 153         for (t = tunnels_l[h1]; t; t = t->next) {
 154                 if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
 155                         return t;
 156         }
 157         if ((t = tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP))
 158                 return t;
 159         return NULL;
 160 }
 161
 162 static struct ip_tunnel **ipip_bucket(struct ip_tunnel *t)
 163 {
 164         u32 remote = t->parms.iph.daddr;
 165         u32 local = t->parms.iph.saddr;
 166         unsigned h = 0;
 167         int prio = 0;
 168
 169         if (remote) {
 170                 prio |= 2;
 171                 h ^= HASH(remote);
 172         }
 173         if (local) {
 174                 prio |= 1;
 175                 h ^= HASH(local);
 176         }
 177         return &tunnels[prio][h];
 178 }
 179
 180
 181 static void ipip_tunnel_unlink(struct ip_tunnel *t)
 182 {
 183         struct ip_tunnel **tp;
 184
 185         for (tp = ipip_bucket(t); *tp; tp = &(*tp)->next) {
 186                 if (t == *tp) {
 187                         write_lock_bh(&ipip_lock);
 188                         *tp = t->next;
 189                         write_unlock_bh(&ipip_lock);
 190                         break;
 191                 }
 192         }
 193 }
 194
 195 static void ipip_tunnel_link(struct ip_tunnel *t)
 196 {
 197         struct ip_tunnel **tp = ipip_bucket(t);
 198
 199         t->next = *tp;
 200         write_lock_bh(&ipip_lock);
 201         *tp = t;
 202         write_unlock_bh(&ipip_lock);
 203 }
 204
 205 static struct ip_tunnel * ipip_tunnel_locate(struct ip_tunnel_parm *parms, int create)
 206 {
 207         u32 remote = parms->iph.daddr;
 208         u32 local = parms->iph.saddr;
 209         struct ip_tunnel *t, **tp, *nt;
 210         struct net_device *dev;
 211         unsigned h = 0;
 212         int prio = 0;
 213         char name[IFNAMSIZ];
 214
 215         if (remote) {
 216                 prio |= 2;
 217                 h ^= HASH(remote);
 218         }
 219         if (local) {
 220                 prio |= 1;
 221                 h ^= HASH(local);
 222         }
 223         for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
 224                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
 225                         return t;
 226         }
 227         if (!create)
 228                 return NULL;
 229
 230         if (parms->name[0])
 231                 strlcpy(name, parms->name, IFNAMSIZ);
 232         else {
 233                 int i;
 234                 for (i=1; i<100; i++) {
 235                         sprintf(name, "tunl%d", i);
 236                         if (__dev_get_by_name(name) == NULL)
 237                                 break;
 238                 }
 239                 if (i==100)
 240                         goto failed;
 241         }
 242
 243         dev = alloc_netdev(sizeof(*t), name, ipip_tunnel_setup);
 244         if (dev == NULL)
 245                 return NULL;
 246
 247         nt = netdev_priv(dev);
 248         SET_MODULE_OWNER(dev);
 249         dev->init = ipip_tunnel_init;
 250         nt->parms = *parms;
 251
 252         if (register_netdevice(dev) < 0) {
 253                 free_netdev(dev);
 254                 goto failed;
 255         }
 256
 257         dev_hold(dev);
 258         ipip_tunnel_link(nt);
 259         return nt;
 260
 261 failed:
 262         return NULL;
 263 }
 264
 265 static void ipip_tunnel_uninit(struct net_device *dev)
 266 {
 267         if (dev == ipip_fb_tunnel_dev) {
 268                 write_lock_bh(&ipip_lock);
 269                 tunnels_wc[0] = NULL;
 270                 write_unlock_bh(&ipip_lock);
 271         } else
 272                 ipip_tunnel_unlink(netdev_priv(dev));
 273         dev_put(dev);
 274 }
 275
 276 static int ipip_err(struct sk_buff *skb, u32 info)
 277 {
 278 #ifndef I_WISH_WORLD_WERE_PERFECT
 279
 280 /* It is not :-( All the routers (except for Linux) return only
 281    8 bytes of packet payload. It means, that precise relaying of
 282    ICMP in the real Internet is absolutely infeasible.
 283  */
 284         struct iphdr *iph = (struct iphdr*)skb->data;
 285         int type = skb->h.icmph->type;
 286         int code = skb->h.icmph->code;
 287         struct ip_tunnel *t;
 288         int err;
 289
 290         switch (type) {
 291         default:
 292         case ICMP_PARAMETERPROB:
 293                 return 0;
 294
 295         case ICMP_DEST_UNREACH:
 296                 switch (code) {
 297                 case ICMP_SR_FAILED:
 298                 case ICMP_PORT_UNREACH:
 299                         /* Impossible event. */
 300                         return 0;
 301                 case ICMP_FRAG_NEEDED:
 302                         /* Soft state for pmtu is maintained by IP core. */
 303                         return 0;
 304                 default:
 305                         /* All others are translated to HOST_UNREACH.
 306                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 307                            I believe they are just ether pollution. --ANK
 308                          */
 309                         break;
 310                 }
 311                 break;
 312         case ICMP_TIME_EXCEEDED:
 313                 if (code != ICMP_EXC_TTL)
 314                         return 0;
 315                 break;
 316         }
 317
 318         err = -ENOENT;
 319
 320         read_lock(&ipip_lock);
 321         t = ipip_tunnel_lookup(iph->daddr, iph->saddr);
 322         if (t == NULL || t->parms.iph.daddr == 0)
 323                 goto out;
 324
 325         err = 0;
 326         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 327                 goto out;
 328
 329         if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
 330                 t->err_count++;
 331         else
 332                 t->err_count = 1;
 333         t->err_time = jiffies;
 334 out:
 335         read_unlock(&ipip_lock);
 336         return err;
 337 #else
 338         struct iphdr *iph = (struct iphdr*)dp;
 339         int hlen = iph->ihl<<2;
 340         struct iphdr *eiph;
 341         int type = skb->h.icmph->type;
 342         int code = skb->h.icmph->code;
 343         int rel_type = 0;
 344         int rel_code = 0;
 345         int rel_info = 0;
 346         struct sk_buff *skb2;
 347         struct flowi fl;
 348         struct rtable *rt;
 349
 350         if (len < hlen + sizeof(struct iphdr))
 351                 return 0;
 352         eiph = (struct iphdr*)(dp + hlen);
 353
 354         switch (type) {
 355         default:
 356                 return 0;
 357         case ICMP_PARAMETERPROB:
 358                 if (skb->h.icmph->un.gateway < hlen)
 359                         return 0;
 360
 361                 /* So... This guy found something strange INSIDE encapsulated
 362                    packet. Well, he is fool, but what can we do ?
 363                  */
 364                 rel_type = ICMP_PARAMETERPROB;
 365                 rel_info = skb->h.icmph->un.gateway - hlen;
 366                 break;
 367
 368         case ICMP_DEST_UNREACH:
 369                 switch (code) {
 370                 case ICMP_SR_FAILED:
 371                 case ICMP_PORT_UNREACH:
 372                         /* Impossible event. */
 373                         return 0;
 374                 case ICMP_FRAG_NEEDED:
 375                         /* And it is the only really necessary thing :-) */
 376                         rel_info = ntohs(skb->h.icmph->un.frag.mtu);
 377                         if (rel_info < hlen+68)
 378                                 return 0;
 379                         rel_info -= hlen;
 380                         /* BSD 4.2 MORE DOES NOT EXIST IN NATURE. */
 381                         if (rel_info > ntohs(eiph->tot_len))
 382                                 return 0;
 383                         break;
 384                 default:
 385                         /* All others are translated to HOST_UNREACH.
 386                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 387                            I believe, it is just ether pollution. --ANK
 388                          */
 389                         rel_type = ICMP_DEST_UNREACH;
 390                         rel_code = ICMP_HOST_UNREACH;
 391                         break;
 392                 }
 393                 break;
 394         case ICMP_TIME_EXCEEDED:
 395                 if (code != ICMP_EXC_TTL)
 396                         return 0;
 397                 break;
 398         }
 399
 400         /* Prepare fake skb to feed it to icmp_send */
 401         skb2 = skb_clone(skb, GFP_ATOMIC);
 402         if (skb2 == NULL)
 403                 return 0;
 404         dst_release(skb2->dst);
 405         skb2->dst = NULL;
 406         skb_pull(skb2, skb->data - (u8*)eiph);
 407         skb2->nh.raw = skb2->data;
 408
 409         /* Try to guess incoming interface */
 410         memset(&fl, 0, sizeof(fl));
 411         fl.fl4_daddr = eiph->saddr;
 412         fl.fl4_tos = RT_TOS(eiph->tos);
 413         fl.proto = IPPROTO_IPIP;
 414         if (ip_route_output_key(&rt, &key)) {
 415                 kfree_skb(skb2);
 416                 return 0;
 417         }
 418         skb2->dev = rt->u.dst.dev;
 419
 420         /* route "incoming" packet */
 421         if (rt->rt_flags&RTCF_LOCAL) {
 422                 ip_rt_put(rt);
 423                 rt = NULL;
 424                 fl.fl4_daddr = eiph->daddr;
 425                 fl.fl4_src = eiph->saddr;
 426                 fl.fl4_tos = eiph->tos;
 427                 if (ip_route_output_key(&rt, &fl) ||
 428                     rt->u.dst.dev->type != ARPHRD_TUNNEL) {
 429                         ip_rt_put(rt);
 430                         kfree_skb(skb2);
 431                         return 0;
 432                 }
 433         } else {
 434                 ip_rt_put(rt);
 435                 if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos, skb2->dev) ||
 436                     skb2->dst->dev->type != ARPHRD_TUNNEL) {
 437                         kfree_skb(skb2);
 438                         return 0;
 439                 }
 440         }
 441
 442         /* change mtu on this route */
 443         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
 444                 if (rel_info > dst_mtu(skb2->dst)) {
 445                         kfree_skb(skb2);
 446                         return 0;
 447                 }
 448                 skb2->dst->ops->update_pmtu(skb2->dst, rel_info);
 449                 rel_info = htonl(rel_info);
 450         } else if (type == ICMP_TIME_EXCEEDED) {
 451                 struct ip_tunnel *t = netdev_priv(skb2->dev);
 452                 if (t->parms.iph.ttl) {
 453                         rel_type = ICMP_DEST_UNREACH;
 454                         rel_code = ICMP_HOST_UNREACH;
 455                 }
 456         }
 457
 458         icmp_send(skb2, rel_type, rel_code, rel_info);
 459         kfree_skb(skb2);
 460         return 0;
 461 #endif
 462 }
 463
 464 static inline void ipip_ecn_decapsulate(struct iphdr *outer_iph, struct sk_buff *skb)
 465 {
 466         struct iphdr *inner_iph = skb->nh.iph;
 467
 468         if (INET_ECN_is_ce(outer_iph->tos))
 469                 IP_ECN_set_ce(inner_iph);
 470 }
 471
 472 static int ipip_rcv(struct sk_buff *skb)
 473 {
 474         struct iphdr *iph;
 475         struct ip_tunnel *tunnel;
 476
 477         iph = skb->nh.iph;
 478
 479         read_lock(&ipip_lock);
 480         if ((tunnel = ipip_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
 481                 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 482                         read_unlock(&ipip_lock);
 483                         kfree_skb(skb);
 484                         return 0;
 485                 }
 486
 487                 secpath_reset(skb);
 488
 489                 skb->mac.raw = skb->nh.raw;
 490                 skb->nh.raw = skb->data;
 491                 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 492                 skb->protocol = htons(ETH_P_IP);
 493                 skb->pkt_type = PACKET_HOST;
 494
 495                 tunnel->stat.rx_packets++;
 496                 tunnel->stat.rx_bytes += skb->len;
 497                 skb->dev = tunnel->dev;
 498                 dst_release(skb->dst);
 499                 skb->dst = NULL;
 500                 nf_reset(skb);
 501                 ipip_ecn_decapsulate(iph, skb);
 502                 netif_rx(skb);
 503                 read_unlock(&ipip_lock);
 504                 return 0;
 505         }
 506         read_unlock(&ipip_lock);
 507
 508         return -1;
 509 }
 510
 511 /*
 512  *      This function assumes it is being called from dev_queue_xmit()
 513  *      and that skb is filled properly by that function.
 514  */
 515
 516 static int ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 517 {
 518         struct ip_tunnel *tunnel = netdev_priv(dev);
 519         struct net_device_stats *stats = &tunnel->stat;
 520         struct iphdr  *tiph = &tunnel->parms.iph;
 521         u8     tos = tunnel->parms.iph.tos;
 522         u16    df = tiph->frag_off;
 523         struct rtable *rt;                      /* Route to the other host */
 524         struct net_device *tdev;                        /* Device to other host */
 525         struct iphdr  *old_iph = skb->nh.iph;
 526         struct iphdr  *iph;                     /* Our new IP header */
 527         int    max_headroom;                    /* The extra header space needed */
 528         u32    dst = tiph->daddr;
 529         int    mtu;
 530
 531         if (tunnel->recursion++) {
 532                 tunnel->stat.collisions++;
 533                 goto tx_error;
 534         }
 535
 536         if (skb->protocol != htons(ETH_P_IP))
 537                 goto tx_error;
 538
 539         if (tos&1)
 540                 tos = old_iph->tos;
 541
 542         if (!dst) {
 543                 /* NBMA tunnel */
 544                 if ((rt = (struct rtable*)skb->dst) == NULL) {
 545                         tunnel->stat.tx_fifo_errors++;
 546                         goto tx_error;
 547                 }
 548                 if ((dst = rt->rt_gateway) == 0)
 549                         goto tx_error_icmp;
 550         }
 551
 552         {
 553                 struct flowi fl = { .oif = tunnel->parms.link,
 554                                     .nl_u = { .ip4_u =
 555                                               { .daddr = dst,
 556                                                 .saddr = tiph->saddr,
 557                                                 .tos = RT_TOS(tos) } },
 558                                     .proto = IPPROTO_IPIP };
 559                 if (ip_route_output_key(&rt, &fl)) {
 560                         tunnel->stat.tx_carrier_errors++;
 561                         goto tx_error_icmp;
 562                 }
 563         }
 564         tdev = rt->u.dst.dev;
 565
 566         if (tdev == dev) {
 567                 ip_rt_put(rt);
 568                 tunnel->stat.collisions++;
 569                 goto tx_error;
 570         }
 571
 572         if (tiph->frag_off)
 573                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 574         else
 575                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 576
 577         if (mtu < 68) {
 578                 tunnel->stat.collisions++;
 579                 ip_rt_put(rt);
 580                 goto tx_error;
 581         }
 582         if (skb->dst)
 583                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 584
 585         df |= (old_iph->frag_off&htons(IP_DF));
 586
 587         if ((old_iph->frag_off&htons(IP_DF)) && mtu < ntohs(old_iph->tot_len)) {
 588                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
 589                 ip_rt_put(rt);
 590                 goto tx_error;
 591         }
 592
 593         if (tunnel->err_count > 0) {
 594                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 595                         tunnel->err_count--;
 596                         dst_link_failure(skb);
 597                 } else
 598                         tunnel->err_count = 0;
 599         }
 600
 601         /*
 602          * Okay, now see if we can stuff it in the buffer as-is.
 603          */
 604         max_headroom = (LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr));
 605
 606         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 607                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 608                 if (!new_skb) {
 609                         ip_rt_put(rt);
 610                         stats->tx_dropped++;
 611                         dev_kfree_skb(skb);
 612                         tunnel->recursion--;
 613                         return 0;
 614                 }
 615                 if (skb->sk)
 616                         skb_set_owner_w(new_skb, skb->sk);
 617                 dev_kfree_skb(skb);
 618                 skb = new_skb;
 619                 old_iph = skb->nh.iph;
 620         }
 621
 622         skb->h.raw = skb->nh.raw;
 623         skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
 624         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 625         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
 626                               IPSKB_REROUTED);
 627         dst_release(skb->dst);
 628         skb->dst = &rt->u.dst;
 629
 630         /*
 631          *      Push down and install the IPIP header.
 632          */
 633
 634         iph                     =       skb->nh.iph;
 635         iph->version            =       4;
 636         iph->ihl                =       sizeof(struct iphdr)>>2;
 637         iph->frag_off           =       df;
 638         iph->protocol           =       IPPROTO_IPIP;
 639         iph->tos                =       INET_ECN_encapsulate(tos, old_iph->tos);
 640         iph->daddr              =       rt->rt_dst;
 641         iph->saddr              =       rt->rt_src;
 642
 643         if ((iph->ttl = tiph->ttl) == 0)
 644                 iph->ttl        =       old_iph->ttl;
 645
 646         nf_reset(skb);
 647
 648         IPTUNNEL_XMIT();
 649         tunnel->recursion--;
 650         return 0;
 651
 652 tx_error_icmp:
 653         dst_link_failure(skb);
 654 tx_error:
 655         stats->tx_errors++;
 656         dev_kfree_skb(skb);
 657         tunnel->recursion--;
 658         return 0;
 659 }
 660
 661 static int
 662 ipip_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 663 {
 664         int err = 0;
 665         struct ip_tunnel_parm p;
 666         struct ip_tunnel *t;
 667
 668         switch (cmd) {
 669         case SIOCGETTUNNEL:
 670                 t = NULL;
 671                 if (dev == ipip_fb_tunnel_dev) {
 672                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 673                                 err = -EFAULT;
 674                                 break;
 675                         }
 676                         t = ipip_tunnel_locate(&p, 0);
 677                 }
 678                 if (t == NULL)
 679                         t = netdev_priv(dev);
 680                 memcpy(&p, &t->parms, sizeof(p));
 681                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 682                         err = -EFAULT;
 683                 break;
 684
 685         case SIOCADDTUNNEL:
 686         case SIOCCHGTUNNEL:
 687                 err = -EPERM;
 688                 if (!capable(CAP_NET_ADMIN))
 689                         goto done;
 690
 691                 err = -EFAULT;
 692                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 693                         goto done;
 694
 695                 err = -EINVAL;
 696                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP ||
 697                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 698                         goto done;
 699                 if (p.iph.ttl)
 700                         p.iph.frag_off |= htons(IP_DF);
 701
 702                 t = ipip_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 703
 704                 if (dev != ipip_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 705                         if (t != NULL) {
 706                                 if (t->dev != dev) {
 707                                         err = -EEXIST;
 708                                         break;
 709                                 }
 710                         } else {
 711                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 712                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 713                                         err = -EINVAL;
 714                                         break;
 715                                 }
 716                                 t = netdev_priv(dev);
 717                                 ipip_tunnel_unlink(t);
 718                                 t->parms.iph.saddr = p.iph.saddr;
 719                                 t->parms.iph.daddr = p.iph.daddr;
 720                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 721                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 722                                 ipip_tunnel_link(t);
 723                                 netdev_state_change(dev);
 724                         }
 725                 }
 726
 727                 if (t) {
 728                         err = 0;
 729                         if (cmd == SIOCCHGTUNNEL) {
 730                                 t->parms.iph.ttl = p.iph.ttl;
 731                                 t->parms.iph.tos = p.iph.tos;
 732                                 t->parms.iph.frag_off = p.iph.frag_off;
 733                         }
 734                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 735                                 err = -EFAULT;
 736                 } else
 737                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 738                 break;
 739
 740         case SIOCDELTUNNEL:
 741                 err = -EPERM;
 742                 if (!capable(CAP_NET_ADMIN))
 743                         goto done;
 744
 745                 if (dev == ipip_fb_tunnel_dev) {
 746                         err = -EFAULT;
 747                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 748                                 goto done;
 749                         err = -ENOENT;
 750                         if ((t = ipip_tunnel_locate(&p, 0)) == NULL)
 751                                 goto done;
 752                         err = -EPERM;
 753                         if (t->dev == ipip_fb_tunnel_dev)
 754                                 goto done;
 755                         dev = t->dev;
 756                 }
 757                 err = unregister_netdevice(dev);
 758                 break;
 759
 760         default:
 761                 err = -EINVAL;
 762         }
 763
 764 done:
 765         return err;
 766 }
 767
 768 static struct net_device_stats *ipip_tunnel_get_stats(struct net_device *dev)
 769 {
 770         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
 771 }
 772
 773 static int ipip_tunnel_change_mtu(struct net_device *dev, int new_mtu)
 774 {
 775         if (new_mtu < 68 || new_mtu > 0xFFF8 - sizeof(struct iphdr))
 776                 return -EINVAL;
 777         dev->mtu = new_mtu;
 778         return 0;
 779 }
 780
 781 static void ipip_tunnel_setup(struct net_device *dev)
 782 {
 783         SET_MODULE_OWNER(dev);
 784         dev->uninit             = ipip_tunnel_uninit;
 785         dev->hard_start_xmit    = ipip_tunnel_xmit;
 786         dev->get_stats          = ipip_tunnel_get_stats;
 787         dev->do_ioctl           = ipip_tunnel_ioctl;
 788         dev->change_mtu         = ipip_tunnel_change_mtu;
 789         dev->destructor         = free_netdev;
 790
 791         dev->type               = ARPHRD_TUNNEL;
 792         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
 793         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
 794         dev->flags              = IFF_NOARP;
 795         dev->iflink             = 0;
 796         dev->addr_len           = 4;
 797 }
 798
 799 static int ipip_tunnel_init(struct net_device *dev)
 800 {
 801         struct net_device *tdev = NULL;
 802         struct ip_tunnel *tunnel;
 803         struct iphdr *iph;
 804
 805         tunnel = netdev_priv(dev);
 806         iph = &tunnel->parms.iph;
 807
 808         tunnel->dev = dev;
 809         strcpy(tunnel->parms.name, dev->name);
 810
 811         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 812         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 813
 814         if (iph->daddr) {
 815                 struct flowi fl = { .oif = tunnel->parms.link,
 816                                     .nl_u = { .ip4_u =
 817                                               { .daddr = iph->daddr,
 818                                                 .saddr = iph->saddr,
 819                                                 .tos = RT_TOS(iph->tos) } },
 820                                     .proto = IPPROTO_IPIP };
 821                 struct rtable *rt;
 822                 if (!ip_route_output_key(&rt, &fl)) {
 823                         tdev = rt->u.dst.dev;
 824                         ip_rt_put(rt);
 825                 }
 826                 dev->flags |= IFF_POINTOPOINT;
 827         }
 828
 829         if (!tdev && tunnel->parms.link)
 830                 tdev = __dev_get_by_index(tunnel->parms.link);
 831
 832         if (tdev) {
 833                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 834                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 835         }
 836         dev->iflink = tunnel->parms.link;
 837
 838         return 0;
 839 }
 840
 841 static int __init ipip_fb_tunnel_init(struct net_device *dev)
 842 {
 843         struct ip_tunnel *tunnel = netdev_priv(dev);
 844         struct iphdr *iph = &tunnel->parms.iph;
 845
 846         tunnel->dev = dev;
 847         strcpy(tunnel->parms.name, dev->name);
 848
 849         iph->version            = 4;
 850         iph->protocol           = IPPROTO_IPIP;
 851         iph->ihl                = 5;
 852
 853         dev_hold(dev);
 854         tunnels_wc[0]           = tunnel;
 855         return 0;
 856 }
 857
 858 static struct xfrm_tunnel ipip_handler = {
 859         .handler        =       ipip_rcv,
 860         .err_handler    =       ipip_err,
 861         .priority       =       1,
 862 };
 863
 864 static char banner[] __initdata =
 865         KERN_INFO "IPv4 over IPv4 tunneling driver\n";
 866
 867 static int __init ipip_init(void)
 868 {
 869         int err;
 870
 871         printk(banner);
 872
 873         if (xfrm4_tunnel_register(&ipip_handler)) {
 874                 printk(KERN_INFO "ipip init: can't register tunnel\n");
 875                 return -EAGAIN;
 876         }
 877
 878         ipip_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel),
 879                                            "tunl0",
 880                                            ipip_tunnel_setup);
 881         if (!ipip_fb_tunnel_dev) {
 882                 err = -ENOMEM;
 883                 goto err1;
 884         }
 885
 886         ipip_fb_tunnel_dev->init = ipip_fb_tunnel_init;
 887
 888         if ((err = register_netdev(ipip_fb_tunnel_dev)))
 889                 goto err2;
 890  out:
 891         return err;
 892  err2:
 893         free_netdev(ipip_fb_tunnel_dev);
 894  err1:
 895         xfrm4_tunnel_deregister(&ipip_handler);
 896         goto out;
 897 }
 898
 899 static void __exit ipip_destroy_tunnels(void)
 900 {
 901         int prio;
 902
 903         for (prio = 1; prio < 4; prio++) {
 904                 int h;
 905                 for (h = 0; h < HASH_SIZE; h++) {
 906                         struct ip_tunnel *t;
 907                         while ((t = tunnels[prio][h]) != NULL)
 908                                 unregister_netdevice(t->dev);
 909                 }
 910         }
 911 }
 912
 913 static void __exit ipip_fini(void)
 914 {
 915         if (xfrm4_tunnel_deregister(&ipip_handler))
 916                 printk(KERN_INFO "ipip close: can't deregister tunnel\n");
 917
 918         rtnl_lock();
 919         ipip_destroy_tunnels();
 920         unregister_netdevice(ipip_fb_tunnel_dev);
 921         rtnl_unlock();
 922 }
 923
 924 module_init(ipip_init);
 925 module_exit(ipip_fini);
 926 MODULE_LICENSE("GPL");