net/ipv4/ipip.c

   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/module.h>
  98 #include <linux/types.h>
  99 #include <linux/kernel.h>
 100 #include <asm/uaccess.h>
 101 #include <linux/skbuff.h>
 102 #include <linux/netdevice.h>
 103 #include <linux/in.h>
 104 #include <linux/tcp.h>
 105 #include <linux/udp.h>
 106 #include <linux/if_arp.h>
 107 #include <linux/mroute.h>
 108 #include <linux/init.h>
 109 #include <linux/netfilter_ipv4.h>
 110 #include <linux/if_ether.h>
 111
 112 #include <net/sock.h>
 113 #include <net/ip.h>
 114 #include <net/icmp.h>
 115 #include <net/ipip.h>
 116 #include <net/inet_ecn.h>
 117 #include <net/xfrm.h>
 118
 119 #define HASH_SIZE  16
 120 #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
 121
 122 static int ipip_fb_tunnel_init(struct net_device *dev);
 123 static int ipip_tunnel_init(struct net_device *dev);
 124 static void ipip_tunnel_setup(struct net_device *dev);
 125
 126 static struct net_device *ipip_fb_tunnel_dev;
 127
 128 static struct ip_tunnel *tunnels_r_l[HASH_SIZE];
 129 static struct ip_tunnel *tunnels_r[HASH_SIZE];
 130 static struct ip_tunnel *tunnels_l[HASH_SIZE];
 131 static struct ip_tunnel *tunnels_wc[1];
 132 static struct ip_tunnel **tunnels[4] = { tunnels_wc, tunnels_l, tunnels_r, tunnels_r_l };
 133
 134 static DEFINE_RWLOCK(ipip_lock);
 135
 136 static struct ip_tunnel * ipip_tunnel_lookup(__be32 remote, __be32 local)
 137 {
 138         unsigned h0 = HASH(remote);
 139         unsigned h1 = HASH(local);
 140         struct ip_tunnel *t;
 141
 142         for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
 143                 if (local == t->parms.iph.saddr &&
 144                     remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
 145                         return t;
 146         }
 147         for (t = tunnels_r[h0]; t; t = t->next) {
 148                 if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
 149                         return t;
 150         }
 151         for (t = tunnels_l[h1]; t; t = t->next) {
 152                 if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
 153                         return t;
 154         }
 155         if ((t = tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP))
 156                 return t;
 157         return NULL;
 158 }
 159
 160 static struct ip_tunnel **__ipip_bucket(struct ip_tunnel_parm *parms)
 161 {
 162         __be32 remote = parms->iph.daddr;
 163         __be32 local = parms->iph.saddr;
 164         unsigned h = 0;
 165         int prio = 0;
 166
 167         if (remote) {
 168                 prio |= 2;
 169                 h ^= HASH(remote);
 170         }
 171         if (local) {
 172                 prio |= 1;
 173                 h ^= HASH(local);
 174         }
 175         return &tunnels[prio][h];
 176 }
 177
 178 static inline struct ip_tunnel **ipip_bucket(struct ip_tunnel *t)
 179 {
 180         return __ipip_bucket(&t->parms);
 181 }
 182
 183 static void ipip_tunnel_unlink(struct ip_tunnel *t)
 184 {
 185         struct ip_tunnel **tp;
 186
 187         for (tp = ipip_bucket(t); *tp; tp = &(*tp)->next) {
 188                 if (t == *tp) {
 189                         write_lock_bh(&ipip_lock);
 190                         *tp = t->next;
 191                         write_unlock_bh(&ipip_lock);
 192                         break;
 193                 }
 194         }
 195 }
 196
 197 static void ipip_tunnel_link(struct ip_tunnel *t)
 198 {
 199         struct ip_tunnel **tp = ipip_bucket(t);
 200
 201         t->next = *tp;
 202         write_lock_bh(&ipip_lock);
 203         *tp = t;
 204         write_unlock_bh(&ipip_lock);
 205 }
 206
 207 static struct ip_tunnel * ipip_tunnel_locate(struct ip_tunnel_parm *parms, int create)
 208 {
 209         __be32 remote = parms->iph.daddr;
 210         __be32 local = parms->iph.saddr;
 211         struct ip_tunnel *t, **tp, *nt;
 212         struct net_device *dev;
 213         char name[IFNAMSIZ];
 214
 215         for (tp = __ipip_bucket(parms); (t = *tp) != NULL; tp = &t->next) {
 216                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
 217                         return t;
 218         }
 219         if (!create)
 220                 return NULL;
 221
 222         if (parms->name[0])
 223                 strlcpy(name, parms->name, IFNAMSIZ);
 224         else {
 225                 int i;
 226                 for (i=1; i<100; i++) {
 227                         sprintf(name, "tunl%d", i);
 228                         if (__dev_get_by_name(name) == NULL)
 229                                 break;
 230                 }
 231                 if (i==100)
 232                         goto failed;
 233         }
 234
 235         dev = alloc_netdev(sizeof(*t), name, ipip_tunnel_setup);
 236         if (dev == NULL)
 237                 return NULL;
 238
 239         nt = netdev_priv(dev);
 240         SET_MODULE_OWNER(dev);
 241         dev->init = ipip_tunnel_init;
 242         nt->parms = *parms;
 243
 244         if (register_netdevice(dev) < 0) {
 245                 free_netdev(dev);
 246                 goto failed;
 247         }
 248
 249         dev_hold(dev);
 250         ipip_tunnel_link(nt);
 251         return nt;
 252
 253 failed:
 254         return NULL;
 255 }
 256
 257 static void ipip_tunnel_uninit(struct net_device *dev)
 258 {
 259         if (dev == ipip_fb_tunnel_dev) {
 260                 write_lock_bh(&ipip_lock);
 261                 tunnels_wc[0] = NULL;
 262                 write_unlock_bh(&ipip_lock);
 263         } else
 264                 ipip_tunnel_unlink(netdev_priv(dev));
 265         dev_put(dev);
 266 }
 267
 268 static int ipip_err(struct sk_buff *skb, u32 info)
 269 {
 270 #ifndef I_WISH_WORLD_WERE_PERFECT
 271
 272 /* It is not :-( All the routers (except for Linux) return only
 273    8 bytes of packet payload. It means, that precise relaying of
 274    ICMP in the real Internet is absolutely infeasible.
 275  */
 276         struct iphdr *iph = (struct iphdr*)skb->data;
 277         const int type = icmp_hdr(skb)->type;
 278         const int code = icmp_hdr(skb)->code;
 279         struct ip_tunnel *t;
 280         int err;
 281
 282         switch (type) {
 283         default:
 284         case ICMP_PARAMETERPROB:
 285                 return 0;
 286
 287         case ICMP_DEST_UNREACH:
 288                 switch (code) {
 289                 case ICMP_SR_FAILED:
 290                 case ICMP_PORT_UNREACH:
 291                         /* Impossible event. */
 292                         return 0;
 293                 case ICMP_FRAG_NEEDED:
 294                         /* Soft state for pmtu is maintained by IP core. */
 295                         return 0;
 296                 default:
 297                         /* All others are translated to HOST_UNREACH.
 298                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 299                            I believe they are just ether pollution. --ANK
 300                          */
 301                         break;
 302                 }
 303                 break;
 304         case ICMP_TIME_EXCEEDED:
 305                 if (code != ICMP_EXC_TTL)
 306                         return 0;
 307                 break;
 308         }
 309
 310         err = -ENOENT;
 311
 312         read_lock(&ipip_lock);
 313         t = ipip_tunnel_lookup(iph->daddr, iph->saddr);
 314         if (t == NULL || t->parms.iph.daddr == 0)
 315                 goto out;
 316
 317         err = 0;
 318         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 319                 goto out;
 320
 321         if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
 322                 t->err_count++;
 323         else
 324                 t->err_count = 1;
 325         t->err_time = jiffies;
 326 out:
 327         read_unlock(&ipip_lock);
 328         return err;
 329 #else
 330         struct iphdr *iph = (struct iphdr*)dp;
 331         int hlen = iph->ihl<<2;
 332         struct iphdr *eiph;
 333         const int type = icmp_hdr(skb)->type;
 334         const int code = icmp_hdr(skb)->code;
 335         int rel_type = 0;
 336         int rel_code = 0;
 337         __be32 rel_info = 0;
 338         __u32 n = 0;
 339         struct sk_buff *skb2;
 340         struct flowi fl;
 341         struct rtable *rt;
 342
 343         if (len < hlen + sizeof(struct iphdr))
 344                 return 0;
 345         eiph = (struct iphdr*)(dp + hlen);
 346
 347         switch (type) {
 348         default:
 349                 return 0;
 350         case ICMP_PARAMETERPROB:
 351                 n = ntohl(icmp_hdr(skb)->un.gateway) >> 24;
 352                 if (n < hlen)
 353                         return 0;
 354
 355                 /* So... This guy found something strange INSIDE encapsulated
 356                    packet. Well, he is fool, but what can we do ?
 357                  */
 358                 rel_type = ICMP_PARAMETERPROB;
 359                 rel_info = htonl((n - hlen) << 24);
 360                 break;
 361
 362         case ICMP_DEST_UNREACH:
 363                 switch (code) {
 364                 case ICMP_SR_FAILED:
 365                 case ICMP_PORT_UNREACH:
 366                         /* Impossible event. */
 367                         return 0;
 368                 case ICMP_FRAG_NEEDED:
 369                         /* And it is the only really necessary thing :-) */
 370                         n = ntohs(icmp_hdr(skb)->un.frag.mtu);
 371                         if (n < hlen+68)
 372                                 return 0;
 373                         n -= hlen;
 374                         /* BSD 4.2 MORE DOES NOT EXIST IN NATURE. */
 375                         if (n > ntohs(eiph->tot_len))
 376                                 return 0;
 377                         rel_info = htonl(n);
 378                         break;
 379                 default:
 380                         /* All others are translated to HOST_UNREACH.
 381                            rfc2003 contains "deep thoughts" about NET_UNREACH,
 382                            I believe, it is just ether pollution. --ANK
 383                          */
 384                         rel_type = ICMP_DEST_UNREACH;
 385                         rel_code = ICMP_HOST_UNREACH;
 386                         break;
 387                 }
 388                 break;
 389         case ICMP_TIME_EXCEEDED:
 390                 if (code != ICMP_EXC_TTL)
 391                         return 0;
 392                 break;
 393         }
 394
 395         /* Prepare fake skb to feed it to icmp_send */
 396         skb2 = skb_clone(skb, GFP_ATOMIC);
 397         if (skb2 == NULL)
 398                 return 0;
 399         dst_release(skb2->dst);
 400         skb2->dst = NULL;
 401         skb_pull(skb2, skb->data - (u8*)eiph);
 402         skb_reset_network_header(skb2);
 403
 404         /* Try to guess incoming interface */
 405         memset(&fl, 0, sizeof(fl));
 406         fl.fl4_daddr = eiph->saddr;
 407         fl.fl4_tos = RT_TOS(eiph->tos);
 408         fl.proto = IPPROTO_IPIP;
 409         if (ip_route_output_key(&rt, &key)) {
 410                 kfree_skb(skb2);
 411                 return 0;
 412         }
 413         skb2->dev = rt->u.dst.dev;
 414
 415         /* route "incoming" packet */
 416         if (rt->rt_flags&RTCF_LOCAL) {
 417                 ip_rt_put(rt);
 418                 rt = NULL;
 419                 fl.fl4_daddr = eiph->daddr;
 420                 fl.fl4_src = eiph->saddr;
 421                 fl.fl4_tos = eiph->tos;
 422                 if (ip_route_output_key(&rt, &fl) ||
 423                     rt->u.dst.dev->type != ARPHRD_TUNNEL) {
 424                         ip_rt_put(rt);
 425                         kfree_skb(skb2);
 426                         return 0;
 427                 }
 428         } else {
 429                 ip_rt_put(rt);
 430                 if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos, skb2->dev) ||
 431                     skb2->dst->dev->type != ARPHRD_TUNNEL) {
 432                         kfree_skb(skb2);
 433                         return 0;
 434                 }
 435         }
 436
 437         /* change mtu on this route */
 438         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
 439                 if (n > dst_mtu(skb2->dst)) {
 440                         kfree_skb(skb2);
 441                         return 0;
 442                 }
 443                 skb2->dst->ops->update_pmtu(skb2->dst, n);
 444         } else if (type == ICMP_TIME_EXCEEDED) {
 445                 struct ip_tunnel *t = netdev_priv(skb2->dev);
 446                 if (t->parms.iph.ttl) {
 447                         rel_type = ICMP_DEST_UNREACH;
 448                         rel_code = ICMP_HOST_UNREACH;
 449                 }
 450         }
 451
 452         icmp_send(skb2, rel_type, rel_code, rel_info);
 453         kfree_skb(skb2);
 454         return 0;
 455 #endif
 456 }
 457
 458 static inline void ipip_ecn_decapsulate(const struct iphdr *outer_iph,
 459                                         struct sk_buff *skb)
 460 {
 461         struct iphdr *inner_iph = ip_hdr(skb);
 462
 463         if (INET_ECN_is_ce(outer_iph->tos))
 464                 IP_ECN_set_ce(inner_iph);
 465 }
 466
 467 static int ipip_rcv(struct sk_buff *skb)
 468 {
 469         struct ip_tunnel *tunnel;
 470         const struct iphdr *iph = ip_hdr(skb);
 471
 472         read_lock(&ipip_lock);
 473         if ((tunnel = ipip_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
 474                 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 475                         read_unlock(&ipip_lock);
 476                         kfree_skb(skb);
 477                         return 0;
 478                 }
 479
 480                 secpath_reset(skb);
 481
 482                 skb->mac_header = skb->network_header;
 483                 skb_reset_network_header(skb);
 484                 skb->protocol = htons(ETH_P_IP);
 485                 skb->pkt_type = PACKET_HOST;
 486
 487                 tunnel->stat.rx_packets++;
 488                 tunnel->stat.rx_bytes += skb->len;
 489                 skb->dev = tunnel->dev;
 490                 dst_release(skb->dst);
 491                 skb->dst = NULL;
 492                 nf_reset(skb);
 493                 ipip_ecn_decapsulate(iph, skb);
 494                 netif_rx(skb);
 495                 read_unlock(&ipip_lock);
 496                 return 0;
 497         }
 498         read_unlock(&ipip_lock);
 499
 500         return -1;
 501 }
 502
 503 /*
 504  *      This function assumes it is being called from dev_queue_xmit()
 505  *      and that skb is filled properly by that function.
 506  */
 507
 508 static int ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 509 {
 510         struct ip_tunnel *tunnel = netdev_priv(dev);
 511         struct net_device_stats *stats = &tunnel->stat;
 512         struct iphdr  *tiph = &tunnel->parms.iph;
 513         u8     tos = tunnel->parms.iph.tos;
 514         __be16 df = tiph->frag_off;
 515         struct rtable *rt;                      /* Route to the other host */
 516         struct net_device *tdev;                        /* Device to other host */
 517         struct iphdr  *old_iph = ip_hdr(skb);
 518         struct iphdr  *iph;                     /* Our new IP header */
 519         int    max_headroom;                    /* The extra header space needed */
 520         __be32 dst = tiph->daddr;
 521         int    mtu;
 522
 523         if (tunnel->recursion++) {
 524                 tunnel->stat.collisions++;
 525                 goto tx_error;
 526         }
 527
 528         if (skb->protocol != htons(ETH_P_IP))
 529                 goto tx_error;
 530
 531         if (tos&1)
 532                 tos = old_iph->tos;
 533
 534         if (!dst) {
 535                 /* NBMA tunnel */
 536                 if ((rt = (struct rtable*)skb->dst) == NULL) {
 537                         tunnel->stat.tx_fifo_errors++;
 538                         goto tx_error;
 539                 }
 540                 if ((dst = rt->rt_gateway) == 0)
 541                         goto tx_error_icmp;
 542         }
 543
 544         {
 545                 struct flowi fl = { .oif = tunnel->parms.link,
 546                                     .nl_u = { .ip4_u =
 547                                               { .daddr = dst,
 548                                                 .saddr = tiph->saddr,
 549                                                 .tos = RT_TOS(tos) } },
 550                                     .proto = IPPROTO_IPIP };
 551                 if (ip_route_output_key(&rt, &fl)) {
 552                         tunnel->stat.tx_carrier_errors++;
 553                         goto tx_error_icmp;
 554                 }
 555         }
 556         tdev = rt->u.dst.dev;
 557
 558         if (tdev == dev) {
 559                 ip_rt_put(rt);
 560                 tunnel->stat.collisions++;
 561                 goto tx_error;
 562         }
 563
 564         if (tiph->frag_off)
 565                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 566         else
 567                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
 568
 569         if (mtu < 68) {
 570                 tunnel->stat.collisions++;
 571                 ip_rt_put(rt);
 572                 goto tx_error;
 573         }
 574         if (skb->dst)
 575                 skb->dst->ops->update_pmtu(skb->dst, mtu);
 576
 577         df |= (old_iph->frag_off&htons(IP_DF));
 578
 579         if ((old_iph->frag_off&htons(IP_DF)) && mtu < ntohs(old_iph->tot_len)) {
 580                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
 581                 ip_rt_put(rt);
 582                 goto tx_error;
 583         }
 584
 585         if (tunnel->err_count > 0) {
 586                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
 587                         tunnel->err_count--;
 588                         dst_link_failure(skb);
 589                 } else
 590                         tunnel->err_count = 0;
 591         }
 592
 593         /*
 594          * Okay, now see if we can stuff it in the buffer as-is.
 595          */
 596         max_headroom = (LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr));
 597
 598         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
 599                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
 600                 if (!new_skb) {
 601                         ip_rt_put(rt);
 602                         stats->tx_dropped++;
 603                         dev_kfree_skb(skb);
 604                         tunnel->recursion--;
 605                         return 0;
 606                 }
 607                 if (skb->sk)
 608                         skb_set_owner_w(new_skb, skb->sk);
 609                 dev_kfree_skb(skb);
 610                 skb = new_skb;
 611                 old_iph = ip_hdr(skb);
 612         }
 613
 614         skb->transport_header = skb->network_header;
 615         skb_push(skb, sizeof(struct iphdr));
 616         skb_reset_network_header(skb);
 617         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 618         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
 619                               IPSKB_REROUTED);
 620         dst_release(skb->dst);
 621         skb->dst = &rt->u.dst;
 622
 623         /*
 624          *      Push down and install the IPIP header.
 625          */
 626
 627         iph                     =       ip_hdr(skb);
 628         iph->version            =       4;
 629         iph->ihl                =       sizeof(struct iphdr)>>2;
 630         iph->frag_off           =       df;
 631         iph->protocol           =       IPPROTO_IPIP;
 632         iph->tos                =       INET_ECN_encapsulate(tos, old_iph->tos);
 633         iph->daddr              =       rt->rt_dst;
 634         iph->saddr              =       rt->rt_src;
 635
 636         if ((iph->ttl = tiph->ttl) == 0)
 637                 iph->ttl        =       old_iph->ttl;
 638
 639         nf_reset(skb);
 640
 641         IPTUNNEL_XMIT();
 642         tunnel->recursion--;
 643         return 0;
 644
 645 tx_error_icmp:
 646         dst_link_failure(skb);
 647 tx_error:
 648         stats->tx_errors++;
 649         dev_kfree_skb(skb);
 650         tunnel->recursion--;
 651         return 0;
 652 }
 653
 654 static int
 655 ipip_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
 656 {
 657         int err = 0;
 658         struct ip_tunnel_parm p;
 659         struct ip_tunnel *t;
 660
 661         switch (cmd) {
 662         case SIOCGETTUNNEL:
 663                 t = NULL;
 664                 if (dev == ipip_fb_tunnel_dev) {
 665                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
 666                                 err = -EFAULT;
 667                                 break;
 668                         }
 669                         t = ipip_tunnel_locate(&p, 0);
 670                 }
 671                 if (t == NULL)
 672                         t = netdev_priv(dev);
 673                 memcpy(&p, &t->parms, sizeof(p));
 674                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 675                         err = -EFAULT;
 676                 break;
 677
 678         case SIOCADDTUNNEL:
 679         case SIOCCHGTUNNEL:
 680                 err = -EPERM;
 681                 if (!capable(CAP_NET_ADMIN))
 682                         goto done;
 683
 684                 err = -EFAULT;
 685                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 686                         goto done;
 687
 688                 err = -EINVAL;
 689                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP ||
 690                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 691                         goto done;
 692                 if (p.iph.ttl)
 693                         p.iph.frag_off |= htons(IP_DF);
 694
 695                 t = ipip_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
 696
 697                 if (dev != ipip_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
 698                         if (t != NULL) {
 699                                 if (t->dev != dev) {
 700                                         err = -EEXIST;
 701                                         break;
 702                                 }
 703                         } else {
 704                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
 705                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
 706                                         err = -EINVAL;
 707                                         break;
 708                                 }
 709                                 t = netdev_priv(dev);
 710                                 ipip_tunnel_unlink(t);
 711                                 t->parms.iph.saddr = p.iph.saddr;
 712                                 t->parms.iph.daddr = p.iph.daddr;
 713                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
 714                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
 715                                 ipip_tunnel_link(t);
 716                                 netdev_state_change(dev);
 717                         }
 718                 }
 719
 720                 if (t) {
 721                         err = 0;
 722                         if (cmd == SIOCCHGTUNNEL) {
 723                                 t->parms.iph.ttl = p.iph.ttl;
 724                                 t->parms.iph.tos = p.iph.tos;
 725                                 t->parms.iph.frag_off = p.iph.frag_off;
 726                         }
 727                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
 728                                 err = -EFAULT;
 729                 } else
 730                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
 731                 break;
 732
 733         case SIOCDELTUNNEL:
 734                 err = -EPERM;
 735                 if (!capable(CAP_NET_ADMIN))
 736                         goto done;
 737
 738                 if (dev == ipip_fb_tunnel_dev) {
 739                         err = -EFAULT;
 740                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 741                                 goto done;
 742                         err = -ENOENT;
 743                         if ((t = ipip_tunnel_locate(&p, 0)) == NULL)
 744                                 goto done;
 745                         err = -EPERM;
 746                         if (t->dev == ipip_fb_tunnel_dev)
 747                                 goto done;
 748                         dev = t->dev;
 749                 }
 750                 unregister_netdevice(dev);
 751                 err = 0;
 752                 break;
 753
 754         default:
 755                 err = -EINVAL;
 756         }
 757
 758 done:
 759         return err;
 760 }
 761
 762 static struct net_device_stats *ipip_tunnel_get_stats(struct net_device *dev)
 763 {
 764         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
 765 }
 766
 767 static int ipip_tunnel_change_mtu(struct net_device *dev, int new_mtu)
 768 {
 769         if (new_mtu < 68 || new_mtu > 0xFFF8 - sizeof(struct iphdr))
 770                 return -EINVAL;
 771         dev->mtu = new_mtu;
 772         return 0;
 773 }
 774
 775 static void ipip_tunnel_setup(struct net_device *dev)
 776 {
 777         SET_MODULE_OWNER(dev);
 778         dev->uninit             = ipip_tunnel_uninit;
 779         dev->hard_start_xmit    = ipip_tunnel_xmit;
 780         dev->get_stats          = ipip_tunnel_get_stats;
 781         dev->do_ioctl           = ipip_tunnel_ioctl;
 782         dev->change_mtu         = ipip_tunnel_change_mtu;
 783         dev->destructor         = free_netdev;
 784
 785         dev->type               = ARPHRD_TUNNEL;
 786         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
 787         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
 788         dev->flags              = IFF_NOARP;
 789         dev->iflink             = 0;
 790         dev->addr_len           = 4;
 791 }
 792
 793 static int ipip_tunnel_init(struct net_device *dev)
 794 {
 795         struct net_device *tdev = NULL;
 796         struct ip_tunnel *tunnel;
 797         struct iphdr *iph;
 798
 799         tunnel = netdev_priv(dev);
 800         iph = &tunnel->parms.iph;
 801
 802         tunnel->dev = dev;
 803         strcpy(tunnel->parms.name, dev->name);
 804
 805         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 806         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 807
 808         if (iph->daddr) {
 809                 struct flowi fl = { .oif = tunnel->parms.link,
 810                                     .nl_u = { .ip4_u =
 811                                               { .daddr = iph->daddr,
 812                                                 .saddr = iph->saddr,
 813                                                 .tos = RT_TOS(iph->tos) } },
 814                                     .proto = IPPROTO_IPIP };
 815                 struct rtable *rt;
 816                 if (!ip_route_output_key(&rt, &fl)) {
 817                         tdev = rt->u.dst.dev;
 818                         ip_rt_put(rt);
 819                 }
 820                 dev->flags |= IFF_POINTOPOINT;
 821         }
 822
 823         if (!tdev && tunnel->parms.link)
 824                 tdev = __dev_get_by_index(tunnel->parms.link);
 825
 826         if (tdev) {
 827                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
 828                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
 829         }
 830         dev->iflink = tunnel->parms.link;
 831
 832         return 0;
 833 }
 834
 835 static int __init ipip_fb_tunnel_init(struct net_device *dev)
 836 {
 837         struct ip_tunnel *tunnel = netdev_priv(dev);
 838         struct iphdr *iph = &tunnel->parms.iph;
 839
 840         tunnel->dev = dev;
 841         strcpy(tunnel->parms.name, dev->name);
 842
 843         iph->version            = 4;
 844         iph->protocol           = IPPROTO_IPIP;
 845         iph->ihl                = 5;
 846
 847         dev_hold(dev);
 848         tunnels_wc[0]           = tunnel;
 849         return 0;
 850 }
 851
 852 static struct xfrm_tunnel ipip_handler = {
 853         .handler        =       ipip_rcv,
 854         .err_handler    =       ipip_err,
 855         .priority       =       1,
 856 };
 857
 858 static char banner[] __initdata =
 859         KERN_INFO "IPv4 over IPv4 tunneling driver\n";
 860
 861 static int __init ipip_init(void)
 862 {
 863         int err;
 864
 865         printk(banner);
 866
 867         if (xfrm4_tunnel_register(&ipip_handler, AF_INET)) {
 868                 printk(KERN_INFO "ipip init: can't register tunnel\n");
 869                 return -EAGAIN;
 870         }
 871
 872         ipip_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel),
 873                                            "tunl0",
 874                                            ipip_tunnel_setup);
 875         if (!ipip_fb_tunnel_dev) {
 876                 err = -ENOMEM;
 877                 goto err1;
 878         }
 879
 880         ipip_fb_tunnel_dev->init = ipip_fb_tunnel_init;
 881
 882         if ((err = register_netdev(ipip_fb_tunnel_dev)))
 883                 goto err2;
 884  out:
 885         return err;
 886  err2:
 887         free_netdev(ipip_fb_tunnel_dev);
 888  err1:
 889         xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
 890         goto out;
 891 }
 892
 893 static void __exit ipip_destroy_tunnels(void)
 894 {
 895         int prio;
 896
 897         for (prio = 1; prio < 4; prio++) {
 898                 int h;
 899                 for (h = 0; h < HASH_SIZE; h++) {
 900                         struct ip_tunnel *t;
 901                         while ((t = tunnels[prio][h]) != NULL)
 902                                 unregister_netdevice(t->dev);
 903                 }
 904         }
 905 }
 906
 907 static void __exit ipip_fini(void)
 908 {
 909         if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET))
 910                 printk(KERN_INFO "ipip close: can't deregister tunnel\n");
 911
 912         rtnl_lock();
 913         ipip_destroy_tunnels();
 914         unregister_netdevice(ipip_fb_tunnel_dev);
 915         rtnl_unlock();
 916 }
 917
 918 module_init(ipip_init);
 919 module_exit(ipip_fini);
 920 MODULE_LICENSE("GPL");