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