xref: /openbmc/linux/net/ipv6/sit.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/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 
37 #include <net/sock.h>
38 #include <net/snmp.h>
39 
40 #include <net/ipv6.h>
41 #include <net/protocol.h>
42 #include <net/transp_v6.h>
43 #include <net/ip6_fib.h>
44 #include <net/ip6_route.h>
45 #include <net/ndisc.h>
46 #include <net/addrconf.h>
47 #include <net/ip.h>
48 #include <net/udp.h>
49 #include <net/icmp.h>
50 #include <net/ipip.h>
51 #include <net/inet_ecn.h>
52 #include <net/xfrm.h>
53 #include <net/dsfield.h>
54 
55 /*
56    This version of net/ipv6/sit.c is cloned of net/ipv4/ip_gre.c
57 
58    For comments look at net/ipv4/ip_gre.c --ANK
59  */
60 
61 #define HASH_SIZE  16
62 #define HASH(addr) ((addr^(addr>>4))&0xF)
63 
64 static int ipip6_fb_tunnel_init(struct net_device *dev);
65 static int ipip6_tunnel_init(struct net_device *dev);
66 static void ipip6_tunnel_setup(struct net_device *dev);
67 
68 static struct net_device *ipip6_fb_tunnel_dev;
69 
70 static struct ip_tunnel *tunnels_r_l[HASH_SIZE];
71 static struct ip_tunnel *tunnels_r[HASH_SIZE];
72 static struct ip_tunnel *tunnels_l[HASH_SIZE];
73 static struct ip_tunnel *tunnels_wc[1];
74 static struct ip_tunnel **tunnels[4] = { tunnels_wc, tunnels_l, tunnels_r, tunnels_r_l };
75 
76 static DEFINE_RWLOCK(ipip6_lock);
77 
78 static struct ip_tunnel * ipip6_tunnel_lookup(u32 remote, u32 local)
79 {
80 	unsigned h0 = HASH(remote);
81 	unsigned h1 = HASH(local);
82 	struct ip_tunnel *t;
83 
84 	for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
85 		if (local == t->parms.iph.saddr &&
86 		    remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
87 			return t;
88 	}
89 	for (t = tunnels_r[h0]; t; t = t->next) {
90 		if (remote == t->parms.iph.daddr && (t->dev->flags&IFF_UP))
91 			return t;
92 	}
93 	for (t = tunnels_l[h1]; t; t = t->next) {
94 		if (local == t->parms.iph.saddr && (t->dev->flags&IFF_UP))
95 			return t;
96 	}
97 	if ((t = tunnels_wc[0]) != NULL && (t->dev->flags&IFF_UP))
98 		return t;
99 	return NULL;
100 }
101 
102 static struct ip_tunnel ** ipip6_bucket(struct ip_tunnel *t)
103 {
104 	u32 remote = t->parms.iph.daddr;
105 	u32 local = t->parms.iph.saddr;
106 	unsigned h = 0;
107 	int prio = 0;
108 
109 	if (remote) {
110 		prio |= 2;
111 		h ^= HASH(remote);
112 	}
113 	if (local) {
114 		prio |= 1;
115 		h ^= HASH(local);
116 	}
117 	return &tunnels[prio][h];
118 }
119 
120 static void ipip6_tunnel_unlink(struct ip_tunnel *t)
121 {
122 	struct ip_tunnel **tp;
123 
124 	for (tp = ipip6_bucket(t); *tp; tp = &(*tp)->next) {
125 		if (t == *tp) {
126 			write_lock_bh(&ipip6_lock);
127 			*tp = t->next;
128 			write_unlock_bh(&ipip6_lock);
129 			break;
130 		}
131 	}
132 }
133 
134 static void ipip6_tunnel_link(struct ip_tunnel *t)
135 {
136 	struct ip_tunnel **tp = ipip6_bucket(t);
137 
138 	t->next = *tp;
139 	write_lock_bh(&ipip6_lock);
140 	*tp = t;
141 	write_unlock_bh(&ipip6_lock);
142 }
143 
144 static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create)
145 {
146 	u32 remote = parms->iph.daddr;
147 	u32 local = parms->iph.saddr;
148 	struct ip_tunnel *t, **tp, *nt;
149 	struct net_device *dev;
150 	unsigned h = 0;
151 	int prio = 0;
152 	char name[IFNAMSIZ];
153 
154 	if (remote) {
155 		prio |= 2;
156 		h ^= HASH(remote);
157 	}
158 	if (local) {
159 		prio |= 1;
160 		h ^= HASH(local);
161 	}
162 	for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
163 		if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
164 			return t;
165 	}
166 	if (!create)
167 		goto failed;
168 
169 	if (parms->name[0])
170 		strlcpy(name, parms->name, IFNAMSIZ);
171 	else {
172 		int i;
173 		for (i=1; i<100; i++) {
174 			sprintf(name, "sit%d", i);
175 			if (__dev_get_by_name(name) == NULL)
176 				break;
177 		}
178 		if (i==100)
179 			goto failed;
180 	}
181 
182 	dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
183 	if (dev == NULL)
184 		return NULL;
185 
186 	nt = dev->priv;
187 	dev->init = ipip6_tunnel_init;
188 	nt->parms = *parms;
189 
190 	if (register_netdevice(dev) < 0) {
191 		free_netdev(dev);
192 		goto failed;
193 	}
194 
195 	dev_hold(dev);
196 
197 	ipip6_tunnel_link(nt);
198 	return nt;
199 
200 failed:
201 	return NULL;
202 }
203 
204 static void ipip6_tunnel_uninit(struct net_device *dev)
205 {
206 	if (dev == ipip6_fb_tunnel_dev) {
207 		write_lock_bh(&ipip6_lock);
208 		tunnels_wc[0] = NULL;
209 		write_unlock_bh(&ipip6_lock);
210 		dev_put(dev);
211 	} else {
212 		ipip6_tunnel_unlink((struct ip_tunnel*)dev->priv);
213 		dev_put(dev);
214 	}
215 }
216 
217 
218 static void ipip6_err(struct sk_buff *skb, u32 info)
219 {
220 #ifndef I_WISH_WORLD_WERE_PERFECT
221 
222 /* It is not :-( All the routers (except for Linux) return only
223    8 bytes of packet payload. It means, that precise relaying of
224    ICMP in the real Internet is absolutely infeasible.
225  */
226 	struct iphdr *iph = (struct iphdr*)skb->data;
227 	int type = skb->h.icmph->type;
228 	int code = skb->h.icmph->code;
229 	struct ip_tunnel *t;
230 
231 	switch (type) {
232 	default:
233 	case ICMP_PARAMETERPROB:
234 		return;
235 
236 	case ICMP_DEST_UNREACH:
237 		switch (code) {
238 		case ICMP_SR_FAILED:
239 		case ICMP_PORT_UNREACH:
240 			/* Impossible event. */
241 			return;
242 		case ICMP_FRAG_NEEDED:
243 			/* Soft state for pmtu is maintained by IP core. */
244 			return;
245 		default:
246 			/* All others are translated to HOST_UNREACH.
247 			   rfc2003 contains "deep thoughts" about NET_UNREACH,
248 			   I believe they are just ether pollution. --ANK
249 			 */
250 			break;
251 		}
252 		break;
253 	case ICMP_TIME_EXCEEDED:
254 		if (code != ICMP_EXC_TTL)
255 			return;
256 		break;
257 	}
258 
259 	read_lock(&ipip6_lock);
260 	t = ipip6_tunnel_lookup(iph->daddr, iph->saddr);
261 	if (t == NULL || t->parms.iph.daddr == 0)
262 		goto out;
263 	if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
264 		goto out;
265 
266 	if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
267 		t->err_count++;
268 	else
269 		t->err_count = 1;
270 	t->err_time = jiffies;
271 out:
272 	read_unlock(&ipip6_lock);
273 	return;
274 #else
275 	struct iphdr *iph = (struct iphdr*)dp;
276 	int hlen = iph->ihl<<2;
277 	struct ipv6hdr *iph6;
278 	int type = skb->h.icmph->type;
279 	int code = skb->h.icmph->code;
280 	int rel_type = 0;
281 	int rel_code = 0;
282 	int rel_info = 0;
283 	struct sk_buff *skb2;
284 	struct rt6_info *rt6i;
285 
286 	if (len < hlen + sizeof(struct ipv6hdr))
287 		return;
288 	iph6 = (struct ipv6hdr*)(dp + hlen);
289 
290 	switch (type) {
291 	default:
292 		return;
293 	case ICMP_PARAMETERPROB:
294 		if (skb->h.icmph->un.gateway < hlen)
295 			return;
296 
297 		/* So... This guy found something strange INSIDE encapsulated
298 		   packet. Well, he is fool, but what can we do ?
299 		 */
300 		rel_type = ICMPV6_PARAMPROB;
301 		rel_info = skb->h.icmph->un.gateway - hlen;
302 		break;
303 
304 	case ICMP_DEST_UNREACH:
305 		switch (code) {
306 		case ICMP_SR_FAILED:
307 		case ICMP_PORT_UNREACH:
308 			/* Impossible event. */
309 			return;
310 		case ICMP_FRAG_NEEDED:
311 			/* Too complicated case ... */
312 			return;
313 		default:
314 			/* All others are translated to HOST_UNREACH.
315 			   rfc2003 contains "deep thoughts" about NET_UNREACH,
316 			   I believe, it is just ether pollution. --ANK
317 			 */
318 			rel_type = ICMPV6_DEST_UNREACH;
319 			rel_code = ICMPV6_ADDR_UNREACH;
320 			break;
321 		}
322 		break;
323 	case ICMP_TIME_EXCEEDED:
324 		if (code != ICMP_EXC_TTL)
325 			return;
326 		rel_type = ICMPV6_TIME_EXCEED;
327 		rel_code = ICMPV6_EXC_HOPLIMIT;
328 		break;
329 	}
330 
331 	/* Prepare fake skb to feed it to icmpv6_send */
332 	skb2 = skb_clone(skb, GFP_ATOMIC);
333 	if (skb2 == NULL)
334 		return;
335 	dst_release(skb2->dst);
336 	skb2->dst = NULL;
337 	skb_pull(skb2, skb->data - (u8*)iph6);
338 	skb2->nh.raw = skb2->data;
339 
340 	/* Try to guess incoming interface */
341 	rt6i = rt6_lookup(&iph6->saddr, NULL, NULL, 0);
342 	if (rt6i && rt6i->rt6i_dev) {
343 		skb2->dev = rt6i->rt6i_dev;
344 
345 		rt6i = rt6_lookup(&iph6->daddr, &iph6->saddr, NULL, 0);
346 
347 		if (rt6i && rt6i->rt6i_dev && rt6i->rt6i_dev->type == ARPHRD_SIT) {
348 			struct ip_tunnel * t = (struct ip_tunnel*)rt6i->rt6i_dev->priv;
349 			if (rel_type == ICMPV6_TIME_EXCEED && t->parms.iph.ttl) {
350 				rel_type = ICMPV6_DEST_UNREACH;
351 				rel_code = ICMPV6_ADDR_UNREACH;
352 			}
353 			icmpv6_send(skb2, rel_type, rel_code, rel_info, skb2->dev);
354 		}
355 	}
356 	kfree_skb(skb2);
357 	return;
358 #endif
359 }
360 
361 static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
362 {
363 	if (INET_ECN_is_ce(iph->tos))
364 		IP6_ECN_set_ce(skb->nh.ipv6h);
365 }
366 
367 static int ipip6_rcv(struct sk_buff *skb)
368 {
369 	struct iphdr *iph;
370 	struct ip_tunnel *tunnel;
371 
372 	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
373 		goto out;
374 
375 	iph = skb->nh.iph;
376 
377 	read_lock(&ipip6_lock);
378 	if ((tunnel = ipip6_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
379 		secpath_reset(skb);
380 		skb->mac.raw = skb->nh.raw;
381 		skb->nh.raw = skb->data;
382 		memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
383 		skb->protocol = htons(ETH_P_IPV6);
384 		skb->pkt_type = PACKET_HOST;
385 		tunnel->stat.rx_packets++;
386 		tunnel->stat.rx_bytes += skb->len;
387 		skb->dev = tunnel->dev;
388 		dst_release(skb->dst);
389 		skb->dst = NULL;
390 		nf_reset(skb);
391 		ipip6_ecn_decapsulate(iph, skb);
392 		netif_rx(skb);
393 		read_unlock(&ipip6_lock);
394 		return 0;
395 	}
396 
397 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
398 	kfree_skb(skb);
399 	read_unlock(&ipip6_lock);
400 out:
401 	return 0;
402 }
403 
404 /* Returns the embedded IPv4 address if the IPv6 address
405    comes from 6to4 (RFC 3056) addr space */
406 
407 static inline u32 try_6to4(struct in6_addr *v6dst)
408 {
409 	u32 dst = 0;
410 
411 	if (v6dst->s6_addr16[0] == htons(0x2002)) {
412 	        /* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
413 		memcpy(&dst, &v6dst->s6_addr16[1], 4);
414 	}
415 	return dst;
416 }
417 
418 /*
419  *	This function assumes it is being called from dev_queue_xmit()
420  *	and that skb is filled properly by that function.
421  */
422 
423 static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
424 {
425 	struct ip_tunnel *tunnel = (struct ip_tunnel*)dev->priv;
426 	struct net_device_stats *stats = &tunnel->stat;
427 	struct iphdr  *tiph = &tunnel->parms.iph;
428 	struct ipv6hdr *iph6 = skb->nh.ipv6h;
429 	u8     tos = tunnel->parms.iph.tos;
430 	struct rtable *rt;     			/* Route to the other host */
431 	struct net_device *tdev;			/* Device to other host */
432 	struct iphdr  *iph;			/* Our new IP header */
433 	int    max_headroom;			/* The extra header space needed */
434 	u32    dst = tiph->daddr;
435 	int    mtu;
436 	struct in6_addr *addr6;
437 	int addr_type;
438 
439 	if (tunnel->recursion++) {
440 		tunnel->stat.collisions++;
441 		goto tx_error;
442 	}
443 
444 	if (skb->protocol != htons(ETH_P_IPV6))
445 		goto tx_error;
446 
447 	if (!dst)
448 		dst = try_6to4(&iph6->daddr);
449 
450 	if (!dst) {
451 		struct neighbour *neigh = NULL;
452 
453 		if (skb->dst)
454 			neigh = skb->dst->neighbour;
455 
456 		if (neigh == NULL) {
457 			if (net_ratelimit())
458 				printk(KERN_DEBUG "sit: nexthop == NULL\n");
459 			goto tx_error;
460 		}
461 
462 		addr6 = (struct in6_addr*)&neigh->primary_key;
463 		addr_type = ipv6_addr_type(addr6);
464 
465 		if (addr_type == IPV6_ADDR_ANY) {
466 			addr6 = &skb->nh.ipv6h->daddr;
467 			addr_type = ipv6_addr_type(addr6);
468 		}
469 
470 		if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
471 			goto tx_error_icmp;
472 
473 		dst = addr6->s6_addr32[3];
474 	}
475 
476 	{
477 		struct flowi fl = { .nl_u = { .ip4_u =
478 					      { .daddr = dst,
479 						.saddr = tiph->saddr,
480 						.tos = RT_TOS(tos) } },
481 				    .oif = tunnel->parms.link,
482 				    .proto = IPPROTO_IPV6 };
483 		if (ip_route_output_key(&rt, &fl)) {
484 			tunnel->stat.tx_carrier_errors++;
485 			goto tx_error_icmp;
486 		}
487 	}
488 	if (rt->rt_type != RTN_UNICAST) {
489 		ip_rt_put(rt);
490 		tunnel->stat.tx_carrier_errors++;
491 		goto tx_error_icmp;
492 	}
493 	tdev = rt->u.dst.dev;
494 
495 	if (tdev == dev) {
496 		ip_rt_put(rt);
497 		tunnel->stat.collisions++;
498 		goto tx_error;
499 	}
500 
501 	if (tiph->frag_off)
502 		mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
503 	else
504 		mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
505 
506 	if (mtu < 68) {
507 		tunnel->stat.collisions++;
508 		ip_rt_put(rt);
509 		goto tx_error;
510 	}
511 	if (mtu < IPV6_MIN_MTU)
512 		mtu = IPV6_MIN_MTU;
513 	if (tunnel->parms.iph.daddr && skb->dst)
514 		skb->dst->ops->update_pmtu(skb->dst, mtu);
515 
516 	if (skb->len > mtu) {
517 		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
518 		ip_rt_put(rt);
519 		goto tx_error;
520 	}
521 
522 	if (tunnel->err_count > 0) {
523 		if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
524 			tunnel->err_count--;
525 			dst_link_failure(skb);
526 		} else
527 			tunnel->err_count = 0;
528 	}
529 
530 	/*
531 	 * Okay, now see if we can stuff it in the buffer as-is.
532 	 */
533 	max_headroom = LL_RESERVED_SPACE(tdev)+sizeof(struct iphdr);
534 
535 	if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
536 		struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
537 		if (!new_skb) {
538 			ip_rt_put(rt);
539   			stats->tx_dropped++;
540 			dev_kfree_skb(skb);
541 			tunnel->recursion--;
542 			return 0;
543 		}
544 		if (skb->sk)
545 			skb_set_owner_w(new_skb, skb->sk);
546 		dev_kfree_skb(skb);
547 		skb = new_skb;
548 		iph6 = skb->nh.ipv6h;
549 	}
550 
551 	skb->h.raw = skb->nh.raw;
552 	skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
553 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
554 	dst_release(skb->dst);
555 	skb->dst = &rt->u.dst;
556 
557 	/*
558 	 *	Push down and install the IPIP header.
559 	 */
560 
561 	iph 			=	skb->nh.iph;
562 	iph->version		=	4;
563 	iph->ihl		=	sizeof(struct iphdr)>>2;
564 	if (mtu > IPV6_MIN_MTU)
565 		iph->frag_off	=	htons(IP_DF);
566 	else
567 		iph->frag_off	=	0;
568 
569 	iph->protocol		=	IPPROTO_IPV6;
570 	iph->tos		=	INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
571 	iph->daddr		=	rt->rt_dst;
572 	iph->saddr		=	rt->rt_src;
573 
574 	if ((iph->ttl = tiph->ttl) == 0)
575 		iph->ttl	=	iph6->hop_limit;
576 
577 	nf_reset(skb);
578 
579 	IPTUNNEL_XMIT();
580 	tunnel->recursion--;
581 	return 0;
582 
583 tx_error_icmp:
584 	dst_link_failure(skb);
585 tx_error:
586 	stats->tx_errors++;
587 	dev_kfree_skb(skb);
588 	tunnel->recursion--;
589 	return 0;
590 }
591 
592 static int
593 ipip6_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
594 {
595 	int err = 0;
596 	struct ip_tunnel_parm p;
597 	struct ip_tunnel *t;
598 
599 	switch (cmd) {
600 	case SIOCGETTUNNEL:
601 		t = NULL;
602 		if (dev == ipip6_fb_tunnel_dev) {
603 			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
604 				err = -EFAULT;
605 				break;
606 			}
607 			t = ipip6_tunnel_locate(&p, 0);
608 		}
609 		if (t == NULL)
610 			t = (struct ip_tunnel*)dev->priv;
611 		memcpy(&p, &t->parms, sizeof(p));
612 		if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
613 			err = -EFAULT;
614 		break;
615 
616 	case SIOCADDTUNNEL:
617 	case SIOCCHGTUNNEL:
618 		err = -EPERM;
619 		if (!capable(CAP_NET_ADMIN))
620 			goto done;
621 
622 		err = -EFAULT;
623 		if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
624 			goto done;
625 
626 		err = -EINVAL;
627 		if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPV6 ||
628 		    p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
629 			goto done;
630 		if (p.iph.ttl)
631 			p.iph.frag_off |= htons(IP_DF);
632 
633 		t = ipip6_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
634 
635 		if (dev != ipip6_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
636 			if (t != NULL) {
637 				if (t->dev != dev) {
638 					err = -EEXIST;
639 					break;
640 				}
641 			} else {
642 				if (((dev->flags&IFF_POINTOPOINT) && !p.iph.daddr) ||
643 				    (!(dev->flags&IFF_POINTOPOINT) && p.iph.daddr)) {
644 					err = -EINVAL;
645 					break;
646 				}
647 				t = (struct ip_tunnel*)dev->priv;
648 				ipip6_tunnel_unlink(t);
649 				t->parms.iph.saddr = p.iph.saddr;
650 				t->parms.iph.daddr = p.iph.daddr;
651 				memcpy(dev->dev_addr, &p.iph.saddr, 4);
652 				memcpy(dev->broadcast, &p.iph.daddr, 4);
653 				ipip6_tunnel_link(t);
654 				netdev_state_change(dev);
655 			}
656 		}
657 
658 		if (t) {
659 			err = 0;
660 			if (cmd == SIOCCHGTUNNEL) {
661 				t->parms.iph.ttl = p.iph.ttl;
662 				t->parms.iph.tos = p.iph.tos;
663 			}
664 			if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
665 				err = -EFAULT;
666 		} else
667 			err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
668 		break;
669 
670 	case SIOCDELTUNNEL:
671 		err = -EPERM;
672 		if (!capable(CAP_NET_ADMIN))
673 			goto done;
674 
675 		if (dev == ipip6_fb_tunnel_dev) {
676 			err = -EFAULT;
677 			if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
678 				goto done;
679 			err = -ENOENT;
680 			if ((t = ipip6_tunnel_locate(&p, 0)) == NULL)
681 				goto done;
682 			err = -EPERM;
683 			if (t == ipip6_fb_tunnel_dev->priv)
684 				goto done;
685 			dev = t->dev;
686 		}
687 		err = unregister_netdevice(dev);
688 		break;
689 
690 	default:
691 		err = -EINVAL;
692 	}
693 
694 done:
695 	return err;
696 }
697 
698 static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev)
699 {
700 	return &(((struct ip_tunnel*)dev->priv)->stat);
701 }
702 
703 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
704 {
705 	if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
706 		return -EINVAL;
707 	dev->mtu = new_mtu;
708 	return 0;
709 }
710 
711 static void ipip6_tunnel_setup(struct net_device *dev)
712 {
713 	SET_MODULE_OWNER(dev);
714 	dev->uninit		= ipip6_tunnel_uninit;
715 	dev->destructor 	= free_netdev;
716 	dev->hard_start_xmit	= ipip6_tunnel_xmit;
717 	dev->get_stats		= ipip6_tunnel_get_stats;
718 	dev->do_ioctl		= ipip6_tunnel_ioctl;
719 	dev->change_mtu		= ipip6_tunnel_change_mtu;
720 
721 	dev->type		= ARPHRD_SIT;
722 	dev->hard_header_len 	= LL_MAX_HEADER + sizeof(struct iphdr);
723 	dev->mtu		= 1500 - sizeof(struct iphdr);
724 	dev->flags		= IFF_NOARP;
725 	dev->iflink		= 0;
726 	dev->addr_len		= 4;
727 }
728 
729 static int ipip6_tunnel_init(struct net_device *dev)
730 {
731 	struct net_device *tdev = NULL;
732 	struct ip_tunnel *tunnel;
733 	struct iphdr *iph;
734 
735 	tunnel = (struct ip_tunnel*)dev->priv;
736 	iph = &tunnel->parms.iph;
737 
738 	tunnel->dev = dev;
739 	strcpy(tunnel->parms.name, dev->name);
740 
741 	memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
742 	memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
743 
744 	if (iph->daddr) {
745 		struct flowi fl = { .nl_u = { .ip4_u =
746 					      { .daddr = iph->daddr,
747 						.saddr = iph->saddr,
748 						.tos = RT_TOS(iph->tos) } },
749 				    .oif = tunnel->parms.link,
750 				    .proto = IPPROTO_IPV6 };
751 		struct rtable *rt;
752 		if (!ip_route_output_key(&rt, &fl)) {
753 			tdev = rt->u.dst.dev;
754 			ip_rt_put(rt);
755 		}
756 		dev->flags |= IFF_POINTOPOINT;
757 	}
758 
759 	if (!tdev && tunnel->parms.link)
760 		tdev = __dev_get_by_index(tunnel->parms.link);
761 
762 	if (tdev) {
763 		dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
764 		dev->mtu = tdev->mtu - sizeof(struct iphdr);
765 		if (dev->mtu < IPV6_MIN_MTU)
766 			dev->mtu = IPV6_MIN_MTU;
767 	}
768 	dev->iflink = tunnel->parms.link;
769 
770 	return 0;
771 }
772 
773 static int __init ipip6_fb_tunnel_init(struct net_device *dev)
774 {
775 	struct ip_tunnel *tunnel = dev->priv;
776 	struct iphdr *iph = &tunnel->parms.iph;
777 
778 	tunnel->dev = dev;
779 	strcpy(tunnel->parms.name, dev->name);
780 
781 	iph->version		= 4;
782 	iph->protocol		= IPPROTO_IPV6;
783 	iph->ihl		= 5;
784 	iph->ttl		= 64;
785 
786 	dev_hold(dev);
787 	tunnels_wc[0]		= tunnel;
788 	return 0;
789 }
790 
791 static struct net_protocol sit_protocol = {
792 	.handler	=	ipip6_rcv,
793 	.err_handler	=	ipip6_err,
794 };
795 
796 static void __exit sit_destroy_tunnels(void)
797 {
798 	int prio;
799 
800 	for (prio = 1; prio < 4; prio++) {
801 		int h;
802 		for (h = 0; h < HASH_SIZE; h++) {
803 			struct ip_tunnel *t;
804 			while ((t = tunnels[prio][h]) != NULL)
805 				unregister_netdevice(t->dev);
806 		}
807 	}
808 }
809 
810 void __exit sit_cleanup(void)
811 {
812 	inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
813 
814 	rtnl_lock();
815 	sit_destroy_tunnels();
816 	unregister_netdevice(ipip6_fb_tunnel_dev);
817 	rtnl_unlock();
818 }
819 
820 int __init sit_init(void)
821 {
822 	int err;
823 
824 	printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
825 
826 	if (inet_add_protocol(&sit_protocol, IPPROTO_IPV6) < 0) {
827 		printk(KERN_INFO "sit init: Can't add protocol\n");
828 		return -EAGAIN;
829 	}
830 
831 	ipip6_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
832 					   ipip6_tunnel_setup);
833 	if (!ipip6_fb_tunnel_dev) {
834 		err = -ENOMEM;
835 		goto err1;
836 	}
837 
838 	ipip6_fb_tunnel_dev->init = ipip6_fb_tunnel_init;
839 
840 	if ((err =  register_netdev(ipip6_fb_tunnel_dev)))
841 		goto err2;
842 
843  out:
844 	return err;
845  err2:
846 	free_netdev(ipip6_fb_tunnel_dev);
847  err1:
848 	inet_del_protocol(&sit_protocol, IPPROTO_IPV6);
849 	goto out;
850 }
851