[INET]: Use port unreachable instead of proto for tunnels
[linux-2.6.git] / net / ipv6 / sit.c
1 /*
2  *      IPv6 over IPv4 tunnel device - Simple Internet Transition (SIT)
3  *      Linux INET6 implementation
4  *
5  *      Authors:
6  *      Pedro Roque             <roque@di.fc.ul.pt>     
7  *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
8  *
9  *      $Id: sit.c,v 1.53 2001/09/25 05:09:53 davem Exp $
10  *
11  *      This program is free software; you can redistribute it and/or
12  *      modify it under the terms of the GNU General Public License
13  *      as published by the Free Software Foundation; either version
14  *      2 of the License, or (at your option) any later version.
15  *
16  *      Changes:
17  * Roger Venning <r.venning@telstra.com>:       6to4 support
18  * Nate Thompson <nate@thebog.net>:             6to4 support
19  */
20
21 #include <linux/config.h>
22 #include <linux/module.h>
23 #include <linux/capability.h>
24 #include <linux/errno.h>
25 #include <linux/types.h>
26 #include <linux/socket.h>
27 #include <linux/sockios.h>
28 #include <linux/sched.h>
29 #include <linux/net.h>
30 #include <linux/in6.h>
31 #include <linux/netdevice.h>
32 #include <linux/if_arp.h>
33 #include <linux/icmp.h>
34 #include <asm/uaccess.h>
35 #include <linux/init.h>
36 #include <linux/netfilter_ipv4.h>
37 #include <linux/if_ether.h>
38
39 #include <net/sock.h>
40 #include <net/snmp.h>
41
42 #include <net/ipv6.h>
43 #include <net/protocol.h>
44 #include <net/transp_v6.h>
45 #include <net/ip6_fib.h>
46 #include <net/ip6_route.h>
47 #include <net/ndisc.h>
48 #include <net/addrconf.h>
49 #include <net/ip.h>
50 #include <net/udp.h>
51 #include <net/icmp.h>
52 #include <net/ipip.h>
53 #include <net/inet_ecn.h>
54 #include <net/xfrm.h>
55 #include <net/dsfield.h>
56
57 /*
58    This version of net/ipv6/sit.c is cloned of net/ipv4/ip_gre.c
59
60    For comments look at net/ipv4/ip_gre.c --ANK
61  */
62
63 #define HASH_SIZE  16
64 #define HASH(addr) ((addr^(addr>>4))&0xF)
65
66 static int ipip6_fb_tunnel_init(struct net_device *dev);
67 static int ipip6_tunnel_init(struct net_device *dev);
68 static void ipip6_tunnel_setup(struct net_device *dev);
69
70 static struct net_device *ipip6_fb_tunnel_dev;
71
72 static struct ip_tunnel *tunnels_r_l[HASH_SIZE];
73 static struct ip_tunnel *tunnels_r[HASH_SIZE];
74 static struct ip_tunnel *tunnels_l[HASH_SIZE];
75 static struct ip_tunnel *tunnels_wc[1];
76 static struct ip_tunnel **tunnels[4] = { tunnels_wc, tunnels_l, tunnels_r, tunnels_r_l };
77
78 static DEFINE_RWLOCK(ipip6_lock);
79
80 static struct ip_tunnel * ipip6_tunnel_lookup(u32 remote, u32 local)
81 {
82         unsigned h0 = HASH(remote);
83         unsigned h1 = HASH(local);
84         struct ip_tunnel *t;
85
86         for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
87                 if (local == t->parms.iph.saddr &&
88                     remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
89                         return t;
90         }
91         for (t = tunnels_r[h0]; t; t = t->next) {
92                 if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
93                         return t;
94         }
95         for (t = tunnels_l[h1]; t; t = t->next) {
96                 if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
97                         return t;
98         }
99         if ((t = tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP))
100                 return t;
101         return NULL;
102 }
103
104 static struct ip_tunnel ** ipip6_bucket(struct ip_tunnel *t)
105 {
106         u32 remote = t->parms.iph.daddr;
107         u32 local = t->parms.iph.saddr;
108         unsigned h = 0;
109         int prio = 0;
110
111         if (remote) {
112                 prio |= 2;
113                 h ^= HASH(remote);
114         }
115         if (local) {
116                 prio |= 1;
117                 h ^= HASH(local);
118         }
119         return &tunnels[prio][h];
120 }
121
122 static void ipip6_tunnel_unlink(struct ip_tunnel *t)
123 {
124         struct ip_tunnel **tp;
125
126         for (tp = ipip6_bucket(t); *tp; tp = &(*tp)->next) {
127                 if (t == *tp) {
128                         write_lock_bh(&ipip6_lock);
129                         *tp = t->next;
130                         write_unlock_bh(&ipip6_lock);
131                         break;
132                 }
133         }
134 }
135
136 static void ipip6_tunnel_link(struct ip_tunnel *t)
137 {
138         struct ip_tunnel **tp = ipip6_bucket(t);
139
140         t->next = *tp;
141         write_lock_bh(&ipip6_lock);
142         *tp = t;
143         write_unlock_bh(&ipip6_lock);
144 }
145
146 static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create)
147 {
148         u32 remote = parms->iph.daddr;
149         u32 local = parms->iph.saddr;
150         struct ip_tunnel *t, **tp, *nt;
151         struct net_device *dev;
152         unsigned h = 0;
153         int prio = 0;
154         char name[IFNAMSIZ];
155
156         if (remote) {
157                 prio |= 2;
158                 h ^= HASH(remote);
159         }
160         if (local) {
161                 prio |= 1;
162                 h ^= HASH(local);
163         }
164         for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
165                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
166                         return t;
167         }
168         if (!create)
169                 goto failed;
170
171         if (parms->name[0])
172                 strlcpy(name, parms->name, IFNAMSIZ);
173         else {
174                 int i;
175                 for (i=1; i<100; i++) {
176                         sprintf(name, "sit%d", i);
177                         if (__dev_get_by_name(name) == NULL)
178                                 break;
179                 }
180                 if (i==100)
181                         goto failed;
182         }
183
184         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
185         if (dev == NULL)
186                 return NULL;
187
188         nt = netdev_priv(dev);
189         dev->init = ipip6_tunnel_init;
190         nt->parms = *parms;
191
192         if (register_netdevice(dev) < 0) {
193                 free_netdev(dev);
194                 goto failed;
195         }
196
197         dev_hold(dev);
198
199         ipip6_tunnel_link(nt);
200         return nt;
201
202 failed:
203         return NULL;
204 }
205
206 static void ipip6_tunnel_uninit(struct net_device *dev)
207 {
208         if (dev == ipip6_fb_tunnel_dev) {
209                 write_lock_bh(&ipip6_lock);
210                 tunnels_wc[0] = NULL;
211                 write_unlock_bh(&ipip6_lock);
212                 dev_put(dev);
213         } else {
214                 ipip6_tunnel_unlink(netdev_priv(dev));
215                 dev_put(dev);
216         }
217 }
218
219
220 static void ipip6_err(struct sk_buff *skb, u32 info)
221 {
222 #ifndef I_WISH_WORLD_WERE_PERFECT
223
224 /* It is not :-( All the routers (except for Linux) return only
225    8 bytes of packet payload. It means, that precise relaying of
226    ICMP in the real Internet is absolutely infeasible.
227  */
228         struct iphdr *iph = (struct iphdr*)skb->data;
229         int type = skb->h.icmph->type;
230         int code = skb->h.icmph->code;
231         struct ip_tunnel *t;
232
233         switch (type) {
234         default:
235         case ICMP_PARAMETERPROB:
236                 return;
237
238         case ICMP_DEST_UNREACH:
239                 switch (code) {
240                 case ICMP_SR_FAILED:
241                 case ICMP_PORT_UNREACH:
242                         /* Impossible event. */
243                         return;
244                 case ICMP_FRAG_NEEDED:
245                         /* Soft state for pmtu is maintained by IP core. */
246                         return;
247                 default:
248                         /* All others are translated to HOST_UNREACH.
249                            rfc2003 contains "deep thoughts" about NET_UNREACH,
250                            I believe they are just ether pollution. --ANK
251                          */
252                         break;
253                 }
254                 break;
255         case ICMP_TIME_EXCEEDED:
256                 if (code != ICMP_EXC_TTL)
257                         return;
258                 break;
259         }
260
261         read_lock(&ipip6_lock);
262         t = ipip6_tunnel_lookup(iph->daddr, iph->saddr);
263         if (t == NULL || t->parms.iph.daddr == 0)
264                 goto out;
265         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
266                 goto out;
267
268         if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
269                 t->err_count++;
270         else
271                 t->err_count = 1;
272         t->err_time = jiffies;
273 out:
274         read_unlock(&ipip6_lock);
275         return;
276 #else
277         struct iphdr *iph = (struct iphdr*)dp;
278         int hlen = iph->ihl<<2;
279         struct ipv6hdr *iph6;
280         int type = skb->h.icmph->type;
281         int code = skb->h.icmph->code;
282         int rel_type = 0;
283         int rel_code = 0;
284         int rel_info = 0;
285         struct sk_buff *skb2;
286         struct rt6_info *rt6i;
287
288         if (len < hlen + sizeof(struct ipv6hdr))
289                 return;
290         iph6 = (struct ipv6hdr*)(dp + hlen);
291
292         switch (type) {
293         default:
294                 return;
295         case ICMP_PARAMETERPROB:
296                 if (skb->h.icmph->un.gateway < hlen)
297                         return;
298
299                 /* So... This guy found something strange INSIDE encapsulated
300                    packet. Well, he is fool, but what can we do ?
301                  */
302                 rel_type = ICMPV6_PARAMPROB;
303                 rel_info = skb->h.icmph->un.gateway - hlen;
304                 break;
305
306         case ICMP_DEST_UNREACH:
307                 switch (code) {
308                 case ICMP_SR_FAILED:
309                 case ICMP_PORT_UNREACH:
310                         /* Impossible event. */
311                         return;
312                 case ICMP_FRAG_NEEDED:
313                         /* Too complicated case ... */
314                         return;
315                 default:
316                         /* All others are translated to HOST_UNREACH.
317                            rfc2003 contains "deep thoughts" about NET_UNREACH,
318                            I believe, it is just ether pollution. --ANK
319                          */
320                         rel_type = ICMPV6_DEST_UNREACH;
321                         rel_code = ICMPV6_ADDR_UNREACH;
322                         break;
323                 }
324                 break;
325         case ICMP_TIME_EXCEEDED:
326                 if (code != ICMP_EXC_TTL)
327                         return;
328                 rel_type = ICMPV6_TIME_EXCEED;
329                 rel_code = ICMPV6_EXC_HOPLIMIT;
330                 break;
331         }
332
333         /* Prepare fake skb to feed it to icmpv6_send */
334         skb2 = skb_clone(skb, GFP_ATOMIC);
335         if (skb2 == NULL)
336                 return;
337         dst_release(skb2->dst);
338         skb2->dst = NULL;
339         skb_pull(skb2, skb->data - (u8*)iph6);
340         skb2->nh.raw = skb2->data;
341
342         /* Try to guess incoming interface */
343         rt6i = rt6_lookup(&iph6->saddr, NULL, NULL, 0);
344         if (rt6i && rt6i->rt6i_dev) {
345                 skb2->dev = rt6i->rt6i_dev;
346
347                 rt6i = rt6_lookup(&iph6->daddr, &iph6->saddr, NULL, 0);
348
349                 if (rt6i && rt6i->rt6i_dev && rt6i->rt6i_dev->type == ARPHRD_SIT) {
350                         struct ip_tunnel *t = netdev_priv(rt6i->rt6i_dev);
351                         if (rel_type == ICMPV6_TIME_EXCEED && t->parms.iph.ttl) {
352                                 rel_type = ICMPV6_DEST_UNREACH;
353                                 rel_code = ICMPV6_ADDR_UNREACH;
354                         }
355                         icmpv6_send(skb2, rel_type, rel_code, rel_info, skb2->dev);
356                 }
357         }
358         kfree_skb(skb2);
359         return;
360 #endif
361 }
362
363 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
364 {
365         if (INET_ECN_is_ce(iph->tos))
366                 IP6_ECN_set_ce(skb->nh.ipv6h);
367 }
368
369 static int ipip6_rcv(struct sk_buff *skb)
370 {
371         struct iphdr *iph;
372         struct ip_tunnel *tunnel;
373
374         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
375                 goto out;
376
377         iph = skb->nh.iph;
378
379         read_lock(&ipip6_lock);
380         if ((tunnel = ipip6_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
381                 secpath_reset(skb);
382                 skb->mac.raw = skb->nh.raw;
383                 skb->nh.raw = skb->data;
384                 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
385                 IPCB(skb)->flags = 0;
386                 skb->protocol = htons(ETH_P_IPV6);
387                 skb->pkt_type = PACKET_HOST;
388                 tunnel->stat.rx_packets++;
389                 tunnel->stat.rx_bytes += skb->len;
390                 skb->dev = tunnel->dev;
391                 dst_release(skb->dst);
392                 skb->dst = NULL;
393                 nf_reset(skb);
394                 ipip6_ecn_decapsulate(iph, skb);
395                 netif_rx(skb);
396                 read_unlock(&ipip6_lock);
397                 return 0;
398         }
399
400         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
401         kfree_skb(skb);
402         read_unlock(&ipip6_lock);
403 out:
404         return 0;
405 }
406
407 /* Returns the embedded IPv4 address if the IPv6 address
408    comes from 6to4 (RFC 3056) addr space */
409
410 static inline u32 try_6to4(struct in6_addr *v6dst)
411 {
412         u32 dst = 0;
413
414         if (v6dst->s6_addr16[0] == htons(0x2002)) {
415                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
416                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
417         }
418         return dst;
419 }
420
421 /*
422  *      This function assumes it is being called from dev_queue_xmit()
423  *      and that skb is filled properly by that function.
424  */
425
426 static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
427 {
428         struct ip_tunnel *tunnel = netdev_priv(dev);
429         struct net_device_stats *stats = &tunnel->stat;
430         struct iphdr  *tiph = &tunnel->parms.iph;
431         struct ipv6hdr *iph6 = skb->nh.ipv6h;
432         u8     tos = tunnel->parms.iph.tos;
433         struct rtable *rt;                      /* Route to the other host */
434         struct net_device *tdev;                        /* Device to other host */
435         struct iphdr  *iph;                     /* Our new IP header */
436         int    max_headroom;                    /* The extra header space needed */
437         u32    dst = tiph->daddr;
438         int    mtu;
439         struct in6_addr *addr6; 
440         int addr_type;
441
442         if (tunnel->recursion++) {
443                 tunnel->stat.collisions++;
444                 goto tx_error;
445         }
446
447         if (skb->protocol != htons(ETH_P_IPV6))
448                 goto tx_error;
449
450         if (!dst)
451                 dst = try_6to4(&iph6->daddr);
452
453         if (!dst) {
454                 struct neighbour *neigh = NULL;
455
456                 if (skb->dst)
457                         neigh = skb->dst->neighbour;
458
459                 if (neigh == NULL) {
460                         if (net_ratelimit())
461                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
462                         goto tx_error;
463                 }
464
465                 addr6 = (struct in6_addr*)&neigh->primary_key;
466                 addr_type = ipv6_addr_type(addr6);
467
468                 if (addr_type == IPV6_ADDR_ANY) {
469                         addr6 = &skb->nh.ipv6h->daddr;
470                         addr_type = ipv6_addr_type(addr6);
471                 }
472
473                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
474                         goto tx_error_icmp;
475
476                 dst = addr6->s6_addr32[3];
477         }
478
479         {
480                 struct flowi fl = { .nl_u = { .ip4_u =
481                                               { .daddr = dst,
482                                                 .saddr = tiph->saddr,
483                                                 .tos = RT_TOS(tos) } },
484                                     .oif = tunnel->parms.link,
485                                     .proto = IPPROTO_IPV6 };
486                 if (ip_route_output_key(&rt, &fl)) {
487                         tunnel->stat.tx_carrier_errors++;
488                         goto tx_error_icmp;
489                 }
490         }
491         if (rt->rt_type != RTN_UNICAST) {
492                 ip_rt_put(rt);
493                 tunnel->stat.tx_carrier_errors++;
494                 goto tx_error_icmp;
495         }
496         tdev = rt->u.dst.dev;
497
498         if (tdev == dev) {
499                 ip_rt_put(rt);
500                 tunnel->stat.collisions++;
501                 goto tx_error;
502         }
503
504         if (tiph->frag_off)
505                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
506         else
507                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
508
509         if (mtu < 68) {
510                 tunnel->stat.collisions++;
511                 ip_rt_put(rt);
512                 goto tx_error;
513         }
514         if (mtu < IPV6_MIN_MTU)
515                 mtu = IPV6_MIN_MTU;
516         if (tunnel->parms.iph.daddr && skb->dst)
517                 skb->dst->ops->update_pmtu(skb->dst, mtu);
518
519         if (skb->len > mtu) {
520                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
521                 ip_rt_put(rt);
522                 goto tx_error;
523         }
524
525         if (tunnel->err_count > 0) {
526                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
527                         tunnel->err_count--;
528                         dst_link_failure(skb);
529                 } else
530                         tunnel->err_count = 0;
531         }
532
533         /*
534          * Okay, now see if we can stuff it in the buffer as-is.
535          */
536         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
537
538         if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
539                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
540                 if (!new_skb) {
541                         ip_rt_put(rt);
542                         stats->tx_dropped++;
543                         dev_kfree_skb(skb);
544                         tunnel->recursion--;
545                         return 0;
546                 }
547                 if (skb->sk)
548                         skb_set_owner_w(new_skb, skb->sk);
549                 dev_kfree_skb(skb);
550                 skb = new_skb;
551                 iph6 = skb->nh.ipv6h;
552         }
553
554         skb->h.raw = skb->nh.raw;
555         skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
556         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
557         IPCB(skb)->flags = 0;
558         dst_release(skb->dst);
559         skb->dst = &rt->u.dst;
560
561         /*
562          *      Push down and install the IPIP header.
563          */
564
565         iph                     =       skb->nh.iph;
566         iph->version            =       4;
567         iph->ihl                =       sizeof(struct iphdr)>>2;
568         if (mtu > IPV6_MIN_MTU)
569                 iph->frag_off   =       htons(IP_DF);
570         else
571                 iph->frag_off   =       0;
572
573         iph->protocol           =       IPPROTO_IPV6;
574         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
575         iph->daddr              =       rt->rt_dst;
576         iph->saddr              =       rt->rt_src;
577
578         if ((iph->ttl = tiph->ttl) == 0)
579                 iph->ttl        =       iph6->hop_limit;
580
581         nf_reset(skb);
582
583         IPTUNNEL_XMIT();
584         tunnel->recursion--;
585         return 0;
586
587 tx_error_icmp:
588         dst_link_failure(skb);
589 tx_error:
590         stats->tx_errors++;
591         dev_kfree_skb(skb);
592         tunnel->recursion--;
593         return 0;
594 }
595
596 static int
597 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
598 {
599         int err = 0;
600         struct ip_tunnel_parm p;
601         struct ip_tunnel *t;
602
603         switch (cmd) {
604         case SIOCGETTUNNEL:
605                 t = NULL;
606                 if (dev == ipip6_fb_tunnel_dev) {
607                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
608                                 err = -EFAULT;
609                                 break;
610                         }
611                         t = ipip6_tunnel_locate(&p, 0);
612                 }
613                 if (t == NULL)
614                         t = netdev_priv(dev);
615                 memcpy(&p, &t->parms, sizeof(p));
616                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
617                         err = -EFAULT;
618                 break;
619
620         case SIOCADDTUNNEL:
621         case SIOCCHGTUNNEL:
622                 err = -EPERM;
623                 if (!capable(CAP_NET_ADMIN))
624                         goto done;
625
626                 err = -EFAULT;
627                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
628                         goto done;
629
630                 err = -EINVAL;
631                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
632                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
633                         goto done;
634                 if (p.iph.ttl)
635                         p.iph.frag_off |= htons(IP_DF);
636
637                 t = ipip6_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
638
639                 if (dev != ipip6_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
640                         if (t != NULL) {
641                                 if (t->dev != dev) {
642                                         err = -EEXIST;
643                                         break;
644                                 }
645                         } else {
646                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
647                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
648                                         err = -EINVAL;
649                                         break;
650                                 }
651                                 t = netdev_priv(dev);
652                                 ipip6_tunnel_unlink(t);
653                                 t->parms.iph.saddr = p.iph.saddr;
654                                 t->parms.iph.daddr = p.iph.daddr;
655                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
656                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
657                                 ipip6_tunnel_link(t);
658                                 netdev_state_change(dev);
659                         }
660                 }
661
662                 if (t) {
663                         err = 0;
664                         if (cmd == SIOCCHGTUNNEL) {
665                                 t->parms.iph.ttl = p.iph.ttl;
666                                 t->parms.iph.tos = p.iph.tos;
667                         }
668                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
669                                 err = -EFAULT;
670                 } else
671                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
672                 break;
673
674         case SIOCDELTUNNEL:
675                 err = -EPERM;
676                 if (!capable(CAP_NET_ADMIN))
677                         goto done;
678
679                 if (dev == ipip6_fb_tunnel_dev) {
680                         err = -EFAULT;
681                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
682                                 goto done;
683                         err = -ENOENT;
684                         if ((t = ipip6_tunnel_locate(&p, 0)) == NULL)
685                                 goto done;
686                         err = -EPERM;
687                         if (t == netdev_priv(ipip6_fb_tunnel_dev))
688                                 goto done;
689                         dev = t->dev;
690                 }
691                 err = unregister_netdevice(dev);
692                 break;
693
694         default:
695                 err = -EINVAL;
696         }
697
698 done:
699         return err;
700 }
701
702 static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev)
703 {
704         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
705 }
706
707 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
708 {
709         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
710                 return -EINVAL;
711         dev->mtu = new_mtu;
712         return 0;
713 }
714
715 static void ipip6_tunnel_setup(struct net_device *dev)
716 {
717         SET_MODULE_OWNER(dev);
718         dev->uninit             = ipip6_tunnel_uninit;
719         dev->destructor         = free_netdev;
720         dev->hard_start_xmit    = ipip6_tunnel_xmit;
721         dev->get_stats          = ipip6_tunnel_get_stats;
722         dev->do_ioctl           = ipip6_tunnel_ioctl;
723         dev->change_mtu         = ipip6_tunnel_change_mtu;
724
725         dev->type               = ARPHRD_SIT;
726         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
727         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
728         dev->flags              = IFF_NOARP;
729         dev->iflink             = 0;
730         dev->addr_len           = 4;
731 }
732
733 static int ipip6_tunnel_init(struct net_device *dev)
734 {
735         struct net_device *tdev = NULL;
736         struct ip_tunnel *tunnel;
737         struct iphdr *iph;
738
739         tunnel = netdev_priv(dev);
740         iph = &tunnel->parms.iph;
741
742         tunnel->dev = dev;
743         strcpy(tunnel->parms.name, dev->name);
744
745         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
746         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
747
748         if (iph->daddr) {
749                 struct flowi fl = { .nl_u = { .ip4_u =
750                                               { .daddr = iph->daddr,
751                                                 .saddr = iph->saddr,
752                                                 .tos = RT_TOS(iph->tos) } },
753                                     .oif = tunnel->parms.link,
754                                     .proto = IPPROTO_IPV6 };
755                 struct rtable *rt;
756                 if (!ip_route_output_key(&rt, &fl)) {
757                         tdev = rt->u.dst.dev;
758                         ip_rt_put(rt);
759                 }
760                 dev->flags |= IFF_POINTOPOINT;
761         }
762
763         if (!tdev && tunnel->parms.link)
764                 tdev = __dev_get_by_index(tunnel->parms.link);
765
766         if (tdev) {
767                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
768                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
769                 if (dev->mtu < IPV6_MIN_MTU)
770                         dev->mtu = IPV6_MIN_MTU;
771         }
772         dev->iflink = tunnel->parms.link;
773
774         return 0;
775 }
776
777 static int __init ipip6_fb_tunnel_init(struct net_device *dev)
778 {
779         struct ip_tunnel *tunnel = netdev_priv(dev);
780         struct iphdr *iph = &tunnel->parms.iph;
781
782         tunnel->dev = dev;
783         strcpy(tunnel->parms.name, dev->name);
784
785         iph->version            = 4;
786         iph->protocol           = IPPROTO_IPV6;
787         iph->ihl                = 5;
788         iph->ttl                = 64;
789
790         dev_hold(dev);
791         tunnels_wc[0]           = tunnel;
792         return 0;
793 }
794
795 static struct net_protocol sit_protocol = {
796         .handler        =       ipip6_rcv,
797         .err_handler    =       ipip6_err,
798 };
799
800 static void __exit sit_destroy_tunnels(void)
801 {
802         int prio;
803
804         for (prio = 1; prio < 4; prio++) {
805                 int h;
806                 for (h = 0; h < HASH_SIZE; h++) {
807                         struct ip_tunnel *t;
808                         while ((t = tunnels[prio][h]) != NULL)
809                                 unregister_netdevice(t->dev);
810                 }
811         }
812 }
813
814 void __exit sit_cleanup(void)
815 {
816         inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
817
818         rtnl_lock();
819         sit_destroy_tunnels();
820         unregister_netdevice(ipip6_fb_tunnel_dev);
821         rtnl_unlock();
822 }
823
824 int __init sit_init(void)
825 {
826         int err;
827
828         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
829
830         if (inet_add_protocol(&sit_protocol, IPPROTO_IPV6) < 0) {
831                 printk(KERN_INFO "sit init: Can't add protocol\n");
832                 return -EAGAIN;
833         }
834
835         ipip6_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0", 
836                                            ipip6_tunnel_setup);
837         if (!ipip6_fb_tunnel_dev) {
838                 err = -ENOMEM;
839                 goto err1;
840         }
841
842         ipip6_fb_tunnel_dev->init = ipip6_fb_tunnel_init;
843
844         if ((err =  register_netdev(ipip6_fb_tunnel_dev)))
845                 goto err2;
846
847  out:
848         return err;
849  err2:
850         free_netdev(ipip6_fb_tunnel_dev);
851  err1:
852         inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
853         goto out;
854 }