Merge branch 'hotfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6
[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  * Fred L. Templin <fltemplin@acm.org>:         isatap support
20  */
21
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/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) (((__force u32)addr^((__force u32)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(__be32 remote, __be32 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_parm *parms)
104 {
105         __be32 remote = parms->iph.daddr;
106         __be32 local = 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 inline struct ip_tunnel **ipip6_bucket(struct ip_tunnel *t)
122 {
123         return __ipip6_bucket(&t->parms);
124 }
125
126 static void ipip6_tunnel_unlink(struct ip_tunnel *t)
127 {
128         struct ip_tunnel **tp;
129
130         for (tp = ipip6_bucket(t); *tp; tp = &(*tp)->next) {
131                 if (t == *tp) {
132                         write_lock_bh(&ipip6_lock);
133                         *tp = t->next;
134                         write_unlock_bh(&ipip6_lock);
135                         break;
136                 }
137         }
138 }
139
140 static void ipip6_tunnel_link(struct ip_tunnel *t)
141 {
142         struct ip_tunnel **tp = ipip6_bucket(t);
143
144         t->next = *tp;
145         write_lock_bh(&ipip6_lock);
146         *tp = t;
147         write_unlock_bh(&ipip6_lock);
148 }
149
150 static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create)
151 {
152         __be32 remote = parms->iph.daddr;
153         __be32 local = parms->iph.saddr;
154         struct ip_tunnel *t, **tp, *nt;
155         struct net_device *dev;
156         char name[IFNAMSIZ];
157
158         for (tp = __ipip6_bucket(parms); (t = *tp) != NULL; tp = &t->next) {
159                 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
160                         return t;
161         }
162         if (!create)
163                 goto failed;
164
165         if (parms->name[0])
166                 strlcpy(name, parms->name, IFNAMSIZ);
167         else
168                 sprintf(name, "sit%%d");
169
170         dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
171         if (dev == NULL)
172                 return NULL;
173
174         if (strchr(name, '%')) {
175                 if (dev_alloc_name(dev, name) < 0)
176                         goto failed_free;
177         }
178
179         nt = netdev_priv(dev);
180         dev->init = ipip6_tunnel_init;
181         nt->parms = *parms;
182
183         if (parms->i_flags & SIT_ISATAP)
184                 dev->priv_flags |= IFF_ISATAP;
185
186         if (register_netdevice(dev) < 0)
187                 goto failed_free;
188
189         dev_hold(dev);
190
191         ipip6_tunnel_link(nt);
192         return nt;
193
194 failed_free:
195         free_netdev(dev);
196 failed:
197         return NULL;
198 }
199
200 static void ipip6_tunnel_uninit(struct net_device *dev)
201 {
202         if (dev == ipip6_fb_tunnel_dev) {
203                 write_lock_bh(&ipip6_lock);
204                 tunnels_wc[0] = NULL;
205                 write_unlock_bh(&ipip6_lock);
206                 dev_put(dev);
207         } else {
208                 ipip6_tunnel_unlink(netdev_priv(dev));
209                 dev_put(dev);
210         }
211 }
212
213
214 static int ipip6_err(struct sk_buff *skb, u32 info)
215 {
216 #ifndef I_WISH_WORLD_WERE_PERFECT
217
218 /* It is not :-( All the routers (except for Linux) return only
219    8 bytes of packet payload. It means, that precise relaying of
220    ICMP in the real Internet is absolutely infeasible.
221  */
222         struct iphdr *iph = (struct iphdr*)skb->data;
223         const int type = icmp_hdr(skb)->type;
224         const int code = icmp_hdr(skb)->code;
225         struct ip_tunnel *t;
226         int err;
227
228         switch (type) {
229         default:
230         case ICMP_PARAMETERPROB:
231                 return 0;
232
233         case ICMP_DEST_UNREACH:
234                 switch (code) {
235                 case ICMP_SR_FAILED:
236                 case ICMP_PORT_UNREACH:
237                         /* Impossible event. */
238                         return 0;
239                 case ICMP_FRAG_NEEDED:
240                         /* Soft state for pmtu is maintained by IP core. */
241                         return 0;
242                 default:
243                         /* All others are translated to HOST_UNREACH.
244                            rfc2003 contains "deep thoughts" about NET_UNREACH,
245                            I believe they are just ether pollution. --ANK
246                          */
247                         break;
248                 }
249                 break;
250         case ICMP_TIME_EXCEEDED:
251                 if (code != ICMP_EXC_TTL)
252                         return 0;
253                 break;
254         }
255
256         err = -ENOENT;
257
258         read_lock(&ipip6_lock);
259         t = ipip6_tunnel_lookup(iph->daddr, iph->saddr);
260         if (t == NULL || t->parms.iph.daddr == 0)
261                 goto out;
262
263         err = 0;
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 err;
275 #else
276         struct iphdr *iph = (struct iphdr*)dp;
277         int hlen = iph->ihl<<2;
278         struct ipv6hdr *iph6;
279         const int type = icmp_hdr(skb)->type;
280         const int code = icmp_hdr(skb)->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 (icmp_hdr(skb)->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 = icmp_hdr(skb)->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 0;
336         dst_release(skb2->dst);
337         skb2->dst = NULL;
338         skb_pull(skb2, skb->data - (u8*)iph6);
339         skb_reset_network_header(skb2);
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 0;
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(ipv6_hdr(skb));
366 }
367
368 /* ISATAP (RFC4214) - check source address */
369 static int
370 isatap_srcok(struct sk_buff *skb, struct iphdr *iph, struct net_device *dev)
371 {
372         struct neighbour *neigh;
373         struct dst_entry *dst;
374         struct rt6_info *rt;
375         struct flowi fl;
376         struct in6_addr *addr6;
377         struct in6_addr rtr;
378         struct ipv6hdr *iph6;
379         int ok = 0;
380
381         /* from onlink default router */
382         ipv6_addr_set(&rtr,  htonl(0xFE800000), 0, 0, 0);
383         ipv6_isatap_eui64(rtr.s6_addr + 8, iph->saddr);
384         if ((rt = rt6_get_dflt_router(&rtr, dev))) {
385                 dst_release(&rt->u.dst);
386                 return 1;
387         }
388
389         iph6 = ipv6_hdr(skb);
390         memset(&fl, 0, sizeof(fl));
391         fl.proto = iph6->nexthdr;
392         ipv6_addr_copy(&fl.fl6_dst, &iph6->saddr);
393         fl.oif = dev->ifindex;
394         security_skb_classify_flow(skb, &fl);
395
396         dst = ip6_route_output(NULL, &fl);
397         if (!dst->error && (dst->dev == dev) && (neigh = dst->neighbour)) {
398
399                 addr6 = (struct in6_addr*)&neigh->primary_key;
400
401                 /* from correct previous hop */
402                 if (ipv6_addr_is_isatap(addr6) &&
403                     (addr6->s6_addr32[3] == iph->saddr))
404                         ok = 1;
405         }
406         dst_release(dst);
407         return ok;
408 }
409
410 static int ipip6_rcv(struct sk_buff *skb)
411 {
412         struct iphdr *iph;
413         struct ip_tunnel *tunnel;
414
415         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
416                 goto out;
417
418         iph = ip_hdr(skb);
419
420         read_lock(&ipip6_lock);
421         if ((tunnel = ipip6_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
422                 secpath_reset(skb);
423                 skb->mac_header = skb->network_header;
424                 skb_reset_network_header(skb);
425                 IPCB(skb)->flags = 0;
426                 skb->protocol = htons(ETH_P_IPV6);
427                 skb->pkt_type = PACKET_HOST;
428
429                 if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
430                     !isatap_srcok(skb, iph, tunnel->dev)) {
431                         tunnel->stat.rx_errors++;
432                         read_unlock(&ipip6_lock);
433                         kfree_skb(skb);
434                         return 0;
435                 }
436                 tunnel->stat.rx_packets++;
437                 tunnel->stat.rx_bytes += skb->len;
438                 skb->dev = tunnel->dev;
439                 dst_release(skb->dst);
440                 skb->dst = NULL;
441                 nf_reset(skb);
442                 ipip6_ecn_decapsulate(iph, skb);
443                 netif_rx(skb);
444                 read_unlock(&ipip6_lock);
445                 return 0;
446         }
447
448         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
449         kfree_skb(skb);
450         read_unlock(&ipip6_lock);
451 out:
452         return 0;
453 }
454
455 /* Returns the embedded IPv4 address if the IPv6 address
456    comes from 6to4 (RFC 3056) addr space */
457
458 static inline __be32 try_6to4(struct in6_addr *v6dst)
459 {
460         __be32 dst = 0;
461
462         if (v6dst->s6_addr16[0] == htons(0x2002)) {
463                 /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
464                 memcpy(&dst, &v6dst->s6_addr16[1], 4);
465         }
466         return dst;
467 }
468
469 /*
470  *      This function assumes it is being called from dev_queue_xmit()
471  *      and that skb is filled properly by that function.
472  */
473
474 static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
475 {
476         struct ip_tunnel *tunnel = netdev_priv(dev);
477         struct net_device_stats *stats = &tunnel->stat;
478         struct iphdr  *tiph = &tunnel->parms.iph;
479         struct ipv6hdr *iph6 = ipv6_hdr(skb);
480         u8     tos = tunnel->parms.iph.tos;
481         struct rtable *rt;                      /* Route to the other host */
482         struct net_device *tdev;                        /* Device to other host */
483         struct iphdr  *iph;                     /* Our new IP header */
484         unsigned int max_headroom;              /* The extra header space needed */
485         __be32 dst = tiph->daddr;
486         int    mtu;
487         struct in6_addr *addr6;
488         int addr_type;
489
490         if (tunnel->recursion++) {
491                 tunnel->stat.collisions++;
492                 goto tx_error;
493         }
494
495         if (skb->protocol != htons(ETH_P_IPV6))
496                 goto tx_error;
497
498         /* ISATAP (RFC4214) - must come before 6to4 */
499         if (dev->priv_flags & IFF_ISATAP) {
500                 struct neighbour *neigh = NULL;
501
502                 if (skb->dst)
503                         neigh = skb->dst->neighbour;
504
505                 if (neigh == NULL) {
506                         if (net_ratelimit())
507                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
508                         goto tx_error;
509                 }
510
511                 addr6 = (struct in6_addr*)&neigh->primary_key;
512                 addr_type = ipv6_addr_type(addr6);
513
514                 if ((addr_type & IPV6_ADDR_UNICAST) &&
515                      ipv6_addr_is_isatap(addr6))
516                         dst = addr6->s6_addr32[3];
517                 else
518                         goto tx_error;
519         }
520
521         if (!dst)
522                 dst = try_6to4(&iph6->daddr);
523
524         if (!dst) {
525                 struct neighbour *neigh = NULL;
526
527                 if (skb->dst)
528                         neigh = skb->dst->neighbour;
529
530                 if (neigh == NULL) {
531                         if (net_ratelimit())
532                                 printk(KERN_DEBUG "sit: nexthop == NULL\n");
533                         goto tx_error;
534                 }
535
536                 addr6 = (struct in6_addr*)&neigh->primary_key;
537                 addr_type = ipv6_addr_type(addr6);
538
539                 if (addr_type == IPV6_ADDR_ANY) {
540                         addr6 = &ipv6_hdr(skb)->daddr;
541                         addr_type = ipv6_addr_type(addr6);
542                 }
543
544                 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
545                         goto tx_error_icmp;
546
547                 dst = addr6->s6_addr32[3];
548         }
549
550         {
551                 struct flowi fl = { .nl_u = { .ip4_u =
552                                               { .daddr = dst,
553                                                 .saddr = tiph->saddr,
554                                                 .tos = RT_TOS(tos) } },
555                                     .oif = tunnel->parms.link,
556                                     .proto = IPPROTO_IPV6 };
557                 if (ip_route_output_key(&init_net, &rt, &fl)) {
558                         tunnel->stat.tx_carrier_errors++;
559                         goto tx_error_icmp;
560                 }
561         }
562         if (rt->rt_type != RTN_UNICAST) {
563                 ip_rt_put(rt);
564                 tunnel->stat.tx_carrier_errors++;
565                 goto tx_error_icmp;
566         }
567         tdev = rt->u.dst.dev;
568
569         if (tdev == dev) {
570                 ip_rt_put(rt);
571                 tunnel->stat.collisions++;
572                 goto tx_error;
573         }
574
575         if (tiph->frag_off)
576                 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
577         else
578                 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
579
580         if (mtu < 68) {
581                 tunnel->stat.collisions++;
582                 ip_rt_put(rt);
583                 goto tx_error;
584         }
585         if (mtu < IPV6_MIN_MTU)
586                 mtu = IPV6_MIN_MTU;
587         if (tunnel->parms.iph.daddr && skb->dst)
588                 skb->dst->ops->update_pmtu(skb->dst, mtu);
589
590         if (skb->len > mtu) {
591                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
592                 ip_rt_put(rt);
593                 goto tx_error;
594         }
595
596         if (tunnel->err_count > 0) {
597                 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
598                         tunnel->err_count--;
599                         dst_link_failure(skb);
600                 } else
601                         tunnel->err_count = 0;
602         }
603
604         /*
605          * Okay, now see if we can stuff it in the buffer as-is.
606          */
607         max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
608
609         if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
610             (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
611                 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
612                 if (!new_skb) {
613                         ip_rt_put(rt);
614                         stats->tx_dropped++;
615                         dev_kfree_skb(skb);
616                         tunnel->recursion--;
617                         return 0;
618                 }
619                 if (skb->sk)
620                         skb_set_owner_w(new_skb, skb->sk);
621                 dev_kfree_skb(skb);
622                 skb = new_skb;
623                 iph6 = ipv6_hdr(skb);
624         }
625
626         skb->transport_header = skb->network_header;
627         skb_push(skb, sizeof(struct iphdr));
628         skb_reset_network_header(skb);
629         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
630         IPCB(skb)->flags = 0;
631         dst_release(skb->dst);
632         skb->dst = &rt->u.dst;
633
634         /*
635          *      Push down and install the IPIP header.
636          */
637
638         iph                     =       ip_hdr(skb);
639         iph->version            =       4;
640         iph->ihl                =       sizeof(struct iphdr)>>2;
641         if (mtu > IPV6_MIN_MTU)
642                 iph->frag_off   =       htons(IP_DF);
643         else
644                 iph->frag_off   =       0;
645
646         iph->protocol           =       IPPROTO_IPV6;
647         iph->tos                =       INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
648         iph->daddr              =       rt->rt_dst;
649         iph->saddr              =       rt->rt_src;
650
651         if ((iph->ttl = tiph->ttl) == 0)
652                 iph->ttl        =       iph6->hop_limit;
653
654         nf_reset(skb);
655
656         IPTUNNEL_XMIT();
657         tunnel->recursion--;
658         return 0;
659
660 tx_error_icmp:
661         dst_link_failure(skb);
662 tx_error:
663         stats->tx_errors++;
664         dev_kfree_skb(skb);
665         tunnel->recursion--;
666         return 0;
667 }
668
669 static void ipip6_tunnel_bind_dev(struct net_device *dev)
670 {
671         struct net_device *tdev = NULL;
672         struct ip_tunnel *tunnel;
673         struct iphdr *iph;
674
675         tunnel = netdev_priv(dev);
676         iph = &tunnel->parms.iph;
677
678         if (iph->daddr) {
679                 struct flowi fl = { .nl_u = { .ip4_u =
680                                               { .daddr = iph->daddr,
681                                                 .saddr = iph->saddr,
682                                                 .tos = RT_TOS(iph->tos) } },
683                                     .oif = tunnel->parms.link,
684                                     .proto = IPPROTO_IPV6 };
685                 struct rtable *rt;
686                 if (!ip_route_output_key(&init_net, &rt, &fl)) {
687                         tdev = rt->u.dst.dev;
688                         ip_rt_put(rt);
689                 }
690                 dev->flags |= IFF_POINTOPOINT;
691         }
692
693         if (!tdev && tunnel->parms.link)
694                 tdev = __dev_get_by_index(&init_net, tunnel->parms.link);
695
696         if (tdev) {
697                 dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
698                 dev->mtu = tdev->mtu - sizeof(struct iphdr);
699                 if (dev->mtu < IPV6_MIN_MTU)
700                         dev->mtu = IPV6_MIN_MTU;
701         }
702         dev->iflink = tunnel->parms.link;
703 }
704
705 static int
706 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
707 {
708         int err = 0;
709         struct ip_tunnel_parm p;
710         struct ip_tunnel *t;
711
712         switch (cmd) {
713         case SIOCGETTUNNEL:
714                 t = NULL;
715                 if (dev == ipip6_fb_tunnel_dev) {
716                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
717                                 err = -EFAULT;
718                                 break;
719                         }
720                         t = ipip6_tunnel_locate(&p, 0);
721                 }
722                 if (t == NULL)
723                         t = netdev_priv(dev);
724                 memcpy(&p, &t->parms, sizeof(p));
725                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
726                         err = -EFAULT;
727                 break;
728
729         case SIOCADDTUNNEL:
730         case SIOCCHGTUNNEL:
731                 err = -EPERM;
732                 if (!capable(CAP_NET_ADMIN))
733                         goto done;
734
735                 err = -EFAULT;
736                 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
737                         goto done;
738
739                 err = -EINVAL;
740                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
741                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
742                         goto done;
743                 if (p.iph.ttl)
744                         p.iph.frag_off |= htons(IP_DF);
745
746                 t = ipip6_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
747
748                 if (dev != ipip6_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
749                         if (t != NULL) {
750                                 if (t->dev != dev) {
751                                         err = -EEXIST;
752                                         break;
753                                 }
754                         } else {
755                                 if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
756                                     (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
757                                         err = -EINVAL;
758                                         break;
759                                 }
760                                 t = netdev_priv(dev);
761                                 ipip6_tunnel_unlink(t);
762                                 t->parms.iph.saddr = p.iph.saddr;
763                                 t->parms.iph.daddr = p.iph.daddr;
764                                 memcpy(dev->dev_addr, &p.iph.saddr, 4);
765                                 memcpy(dev->broadcast, &p.iph.daddr, 4);
766                                 ipip6_tunnel_link(t);
767                                 netdev_state_change(dev);
768                         }
769                 }
770
771                 if (t) {
772                         err = 0;
773                         if (cmd == SIOCCHGTUNNEL) {
774                                 t->parms.iph.ttl = p.iph.ttl;
775                                 t->parms.iph.tos = p.iph.tos;
776                                 if (t->parms.link != p.link) {
777                                         t->parms.link = p.link;
778                                         ipip6_tunnel_bind_dev(dev);
779                                         netdev_state_change(dev);
780                                 }
781                         }
782                         if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
783                                 err = -EFAULT;
784                 } else
785                         err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
786                 break;
787
788         case SIOCDELTUNNEL:
789                 err = -EPERM;
790                 if (!capable(CAP_NET_ADMIN))
791                         goto done;
792
793                 if (dev == ipip6_fb_tunnel_dev) {
794                         err = -EFAULT;
795                         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
796                                 goto done;
797                         err = -ENOENT;
798                         if ((t = ipip6_tunnel_locate(&p, 0)) == NULL)
799                                 goto done;
800                         err = -EPERM;
801                         if (t == netdev_priv(ipip6_fb_tunnel_dev))
802                                 goto done;
803                         dev = t->dev;
804                 }
805                 unregister_netdevice(dev);
806                 err = 0;
807                 break;
808
809         default:
810                 err = -EINVAL;
811         }
812
813 done:
814         return err;
815 }
816
817 static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev)
818 {
819         return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
820 }
821
822 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
823 {
824         if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
825                 return -EINVAL;
826         dev->mtu = new_mtu;
827         return 0;
828 }
829
830 static void ipip6_tunnel_setup(struct net_device *dev)
831 {
832         dev->uninit             = ipip6_tunnel_uninit;
833         dev->destructor         = free_netdev;
834         dev->hard_start_xmit    = ipip6_tunnel_xmit;
835         dev->get_stats          = ipip6_tunnel_get_stats;
836         dev->do_ioctl           = ipip6_tunnel_ioctl;
837         dev->change_mtu         = ipip6_tunnel_change_mtu;
838
839         dev->type               = ARPHRD_SIT;
840         dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
841         dev->mtu                = ETH_DATA_LEN - sizeof(struct iphdr);
842         dev->flags              = IFF_NOARP;
843         dev->iflink             = 0;
844         dev->addr_len           = 4;
845 }
846
847 static int ipip6_tunnel_init(struct net_device *dev)
848 {
849         struct ip_tunnel *tunnel;
850
851         tunnel = netdev_priv(dev);
852
853         tunnel->dev = dev;
854         strcpy(tunnel->parms.name, dev->name);
855
856         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
857         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
858
859         ipip6_tunnel_bind_dev(dev);
860
861         return 0;
862 }
863
864 static int __init ipip6_fb_tunnel_init(struct net_device *dev)
865 {
866         struct ip_tunnel *tunnel = netdev_priv(dev);
867         struct iphdr *iph = &tunnel->parms.iph;
868
869         tunnel->dev = dev;
870         strcpy(tunnel->parms.name, dev->name);
871
872         iph->version            = 4;
873         iph->protocol           = IPPROTO_IPV6;
874         iph->ihl                = 5;
875         iph->ttl                = 64;
876
877         dev_hold(dev);
878         tunnels_wc[0]           = tunnel;
879         return 0;
880 }
881
882 static struct xfrm_tunnel sit_handler = {
883         .handler        =       ipip6_rcv,
884         .err_handler    =       ipip6_err,
885         .priority       =       1,
886 };
887
888 static void __exit sit_destroy_tunnels(void)
889 {
890         int prio;
891
892         for (prio = 1; prio < 4; prio++) {
893                 int h;
894                 for (h = 0; h < HASH_SIZE; h++) {
895                         struct ip_tunnel *t;
896                         while ((t = tunnels[prio][h]) != NULL)
897                                 unregister_netdevice(t->dev);
898                 }
899         }
900 }
901
902 static void __exit sit_cleanup(void)
903 {
904         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
905
906         rtnl_lock();
907         sit_destroy_tunnels();
908         unregister_netdevice(ipip6_fb_tunnel_dev);
909         rtnl_unlock();
910 }
911
912 static int __init sit_init(void)
913 {
914         int err;
915
916         printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
917
918         if (xfrm4_tunnel_register(&sit_handler, AF_INET6) < 0) {
919                 printk(KERN_INFO "sit init: Can't add protocol\n");
920                 return -EAGAIN;
921         }
922
923         ipip6_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
924                                            ipip6_tunnel_setup);
925         if (!ipip6_fb_tunnel_dev) {
926                 err = -ENOMEM;
927                 goto err1;
928         }
929
930         ipip6_fb_tunnel_dev->init = ipip6_fb_tunnel_init;
931
932         if ((err =  register_netdev(ipip6_fb_tunnel_dev)))
933                 goto err2;
934
935  out:
936         return err;
937  err2:
938         free_netdev(ipip6_fb_tunnel_dev);
939  err1:
940         xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
941         goto out;
942 }
943
944 module_init(sit_init);
945 module_exit(sit_cleanup);
946 MODULE_LICENSE("GPL");
947 MODULE_ALIAS("sit0");