xref: /openbmc/linux/net/ipv6/sit.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/net.h>
28 #include <linux/in6.h>
29 #include <linux/netdevice.h>
30 #include <linux/if_arp.h>
31 #include <linux/icmp.h>
32 #include <asm/uaccess.h>
33 #include <linux/init.h>
34 #include <linux/netfilter_ipv4.h>
35 #include <linux/if_ether.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) (((__force u32)addr^((__force u32)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(__be32 remote, __be32 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_parm *parms)
103 {
104 	__be32 remote = parms->iph.daddr;
105 	__be32 local = 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 inline struct ip_tunnel **ipip6_bucket(struct ip_tunnel *t)
121 {
122 	return __ipip6_bucket(&t->parms);
123 }
124 
125 static void ipip6_tunnel_unlink(struct ip_tunnel *t)
126 {
127 	struct ip_tunnel **tp;
128 
129 	for (tp = ipip6_bucket(t); *tp; tp = &(*tp)->next) {
130 		if (t == *tp) {
131 			write_lock_bh(&ipip6_lock);
132 			*tp = t->next;
133 			write_unlock_bh(&ipip6_lock);
134 			break;
135 		}
136 	}
137 }
138 
139 static void ipip6_tunnel_link(struct ip_tunnel *t)
140 {
141 	struct ip_tunnel **tp = ipip6_bucket(t);
142 
143 	t->next = *tp;
144 	write_lock_bh(&ipip6_lock);
145 	*tp = t;
146 	write_unlock_bh(&ipip6_lock);
147 }
148 
149 static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int create)
150 {
151 	__be32 remote = parms->iph.daddr;
152 	__be32 local = parms->iph.saddr;
153 	struct ip_tunnel *t, **tp, *nt;
154 	struct net_device *dev;
155 	char name[IFNAMSIZ];
156 
157 	for (tp = __ipip6_bucket(parms); (t = *tp) != NULL; tp = &t->next) {
158 		if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr)
159 			return t;
160 	}
161 	if (!create)
162 		goto failed;
163 
164 	if (parms->name[0])
165 		strlcpy(name, parms->name, IFNAMSIZ);
166 	else {
167 		int i;
168 		for (i=1; i<100; i++) {
169 			sprintf(name, "sit%d", i);
170 			if (__dev_get_by_name(name) == NULL)
171 				break;
172 		}
173 		if (i==100)
174 			goto failed;
175 	}
176 
177 	dev = alloc_netdev(sizeof(*t), name, ipip6_tunnel_setup);
178 	if (dev == NULL)
179 		return NULL;
180 
181 	nt = netdev_priv(dev);
182 	dev->init = ipip6_tunnel_init;
183 	nt->parms = *parms;
184 
185 	if (register_netdevice(dev) < 0) {
186 		free_netdev(dev);
187 		goto failed;
188 	}
189 
190 	dev_hold(dev);
191 
192 	ipip6_tunnel_link(nt);
193 	return nt;
194 
195 failed:
196 	return NULL;
197 }
198 
199 static void ipip6_tunnel_uninit(struct net_device *dev)
200 {
201 	if (dev == ipip6_fb_tunnel_dev) {
202 		write_lock_bh(&ipip6_lock);
203 		tunnels_wc[0] = NULL;
204 		write_unlock_bh(&ipip6_lock);
205 		dev_put(dev);
206 	} else {
207 		ipip6_tunnel_unlink(netdev_priv(dev));
208 		dev_put(dev);
209 	}
210 }
211 
212 
213 static int ipip6_err(struct sk_buff *skb, u32 info)
214 {
215 #ifndef I_WISH_WORLD_WERE_PERFECT
216 
217 /* It is not :-( All the routers (except for Linux) return only
218    8 bytes of packet payload. It means, that precise relaying of
219    ICMP in the real Internet is absolutely infeasible.
220  */
221 	struct iphdr *iph = (struct iphdr*)skb->data;
222 	const int type = icmp_hdr(skb)->type;
223 	const int code = icmp_hdr(skb)->code;
224 	struct ip_tunnel *t;
225 	int err;
226 
227 	switch (type) {
228 	default:
229 	case ICMP_PARAMETERPROB:
230 		return 0;
231 
232 	case ICMP_DEST_UNREACH:
233 		switch (code) {
234 		case ICMP_SR_FAILED:
235 		case ICMP_PORT_UNREACH:
236 			/* Impossible event. */
237 			return 0;
238 		case ICMP_FRAG_NEEDED:
239 			/* Soft state for pmtu is maintained by IP core. */
240 			return 0;
241 		default:
242 			/* All others are translated to HOST_UNREACH.
243 			   rfc2003 contains "deep thoughts" about NET_UNREACH,
244 			   I believe they are just ether pollution. --ANK
245 			 */
246 			break;
247 		}
248 		break;
249 	case ICMP_TIME_EXCEEDED:
250 		if (code != ICMP_EXC_TTL)
251 			return 0;
252 		break;
253 	}
254 
255 	err = -ENOENT;
256 
257 	read_lock(&ipip6_lock);
258 	t = ipip6_tunnel_lookup(iph->daddr, iph->saddr);
259 	if (t == NULL || t->parms.iph.daddr == 0)
260 		goto out;
261 
262 	err = 0;
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 err;
274 #else
275 	struct iphdr *iph = (struct iphdr*)dp;
276 	int hlen = iph->ihl<<2;
277 	struct ipv6hdr *iph6;
278 	const int type = icmp_hdr(skb)->type;
279 	const int code = icmp_hdr(skb)->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 (icmp_hdr(skb)->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 = icmp_hdr(skb)->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 0;
335 	dst_release(skb2->dst);
336 	skb2->dst = NULL;
337 	skb_pull(skb2, skb->data - (u8*)iph6);
338 	skb_reset_network_header(skb2);
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 = netdev_priv(rt6i->rt6i_dev);
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 0;
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(ipv6_hdr(skb));
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 = ip_hdr(skb);
376 
377 	read_lock(&ipip6_lock);
378 	if ((tunnel = ipip6_tunnel_lookup(iph->saddr, iph->daddr)) != NULL) {
379 		secpath_reset(skb);
380 		skb->mac_header = skb->network_header;
381 		skb_reset_network_header(skb);
382 		IPCB(skb)->flags = 0;
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_PORT_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 __be32 try_6to4(struct in6_addr *v6dst)
408 {
409 	__be32 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 = netdev_priv(dev);
426 	struct net_device_stats *stats = &tunnel->stat;
427 	struct iphdr  *tiph = &tunnel->parms.iph;
428 	struct ipv6hdr *iph6 = ipv6_hdr(skb);
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 	__be32 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 = &ipv6_hdr(skb)->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 = ipv6_hdr(skb);
549 	}
550 
551 	skb->transport_header = skb->network_header;
552 	skb_push(skb, sizeof(struct iphdr));
553 	skb_reset_network_header(skb);
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 			=	ip_hdr(skb);
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 		unregister_netdevice(dev);
690 		err = 0;
691 		break;
692 
693 	default:
694 		err = -EINVAL;
695 	}
696 
697 done:
698 	return err;
699 }
700 
701 static struct net_device_stats *ipip6_tunnel_get_stats(struct net_device *dev)
702 {
703 	return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
704 }
705 
706 static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
707 {
708 	if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - sizeof(struct iphdr))
709 		return -EINVAL;
710 	dev->mtu = new_mtu;
711 	return 0;
712 }
713 
714 static void ipip6_tunnel_setup(struct net_device *dev)
715 {
716 	SET_MODULE_OWNER(dev);
717 	dev->uninit		= ipip6_tunnel_uninit;
718 	dev->destructor 	= free_netdev;
719 	dev->hard_start_xmit	= ipip6_tunnel_xmit;
720 	dev->get_stats		= ipip6_tunnel_get_stats;
721 	dev->do_ioctl		= ipip6_tunnel_ioctl;
722 	dev->change_mtu		= ipip6_tunnel_change_mtu;
723 
724 	dev->type		= ARPHRD_SIT;
725 	dev->hard_header_len 	= LL_MAX_HEADER + sizeof(struct iphdr);
726 	dev->mtu		= ETH_DATA_LEN - sizeof(struct iphdr);
727 	dev->flags		= IFF_NOARP;
728 	dev->iflink		= 0;
729 	dev->addr_len		= 4;
730 }
731 
732 static int ipip6_tunnel_init(struct net_device *dev)
733 {
734 	struct net_device *tdev = NULL;
735 	struct ip_tunnel *tunnel;
736 	struct iphdr *iph;
737 
738 	tunnel = netdev_priv(dev);
739 	iph = &tunnel->parms.iph;
740 
741 	tunnel->dev = dev;
742 	strcpy(tunnel->parms.name, dev->name);
743 
744 	memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
745 	memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
746 
747 	if (iph->daddr) {
748 		struct flowi fl = { .nl_u = { .ip4_u =
749 					      { .daddr = iph->daddr,
750 						.saddr = iph->saddr,
751 						.tos = RT_TOS(iph->tos) } },
752 				    .oif = tunnel->parms.link,
753 				    .proto = IPPROTO_IPV6 };
754 		struct rtable *rt;
755 		if (!ip_route_output_key(&rt, &fl)) {
756 			tdev = rt->u.dst.dev;
757 			ip_rt_put(rt);
758 		}
759 		dev->flags |= IFF_POINTOPOINT;
760 	}
761 
762 	if (!tdev && tunnel->parms.link)
763 		tdev = __dev_get_by_index(tunnel->parms.link);
764 
765 	if (tdev) {
766 		dev->hard_header_len = tdev->hard_header_len + sizeof(struct iphdr);
767 		dev->mtu = tdev->mtu - sizeof(struct iphdr);
768 		if (dev->mtu < IPV6_MIN_MTU)
769 			dev->mtu = IPV6_MIN_MTU;
770 	}
771 	dev->iflink = tunnel->parms.link;
772 
773 	return 0;
774 }
775 
776 static int __init ipip6_fb_tunnel_init(struct net_device *dev)
777 {
778 	struct ip_tunnel *tunnel = netdev_priv(dev);
779 	struct iphdr *iph = &tunnel->parms.iph;
780 
781 	tunnel->dev = dev;
782 	strcpy(tunnel->parms.name, dev->name);
783 
784 	iph->version		= 4;
785 	iph->protocol		= IPPROTO_IPV6;
786 	iph->ihl		= 5;
787 	iph->ttl		= 64;
788 
789 	dev_hold(dev);
790 	tunnels_wc[0]		= tunnel;
791 	return 0;
792 }
793 
794 static struct xfrm_tunnel sit_handler = {
795 	.handler	=	ipip6_rcv,
796 	.err_handler	=	ipip6_err,
797 	.priority	=	1,
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 static void __exit sit_cleanup(void)
815 {
816 	xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
817 
818 	rtnl_lock();
819 	sit_destroy_tunnels();
820 	unregister_netdevice(ipip6_fb_tunnel_dev);
821 	rtnl_unlock();
822 }
823 
824 static int __init sit_init(void)
825 {
826 	int err;
827 
828 	printk(KERN_INFO "IPv6 over IPv4 tunneling driver\n");
829 
830 	if (xfrm4_tunnel_register(&sit_handler, AF_INET6) < 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 	xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
853 	goto out;
854 }
855 
856 module_init(sit_init);
857 module_exit(sit_cleanup);
858 MODULE_LICENSE("GPL");
859 MODULE_ALIAS("sit0");
860