xref: /linux/net/ipv6/sit.c (revision be239684b18e1cdcafcf8c7face4a2f562c745ad)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	IPv6 over IPv4 tunnel device - Simple Internet Transition (SIT)
4  *	Linux INET6 implementation
5  *
6  *	Authors:
7  *	Pedro Roque		<roque@di.fc.ul.pt>
8  *	Alexey Kuznetsov	<kuznet@ms2.inr.ac.ru>
9  *
10  *	Changes:
11  * Roger Venning <r.venning@telstra.com>:	6to4 support
12  * Nate Thompson <nate@thebog.net>:		6to4 support
13  * Fred Templin <fred.l.templin@boeing.com>:	isatap support
14  */
15 
16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17 
18 #include <linux/module.h>
19 #include <linux/capability.h>
20 #include <linux/errno.h>
21 #include <linux/types.h>
22 #include <linux/socket.h>
23 #include <linux/sockios.h>
24 #include <linux/net.h>
25 #include <linux/in6.h>
26 #include <linux/netdevice.h>
27 #include <linux/if_arp.h>
28 #include <linux/icmp.h>
29 #include <linux/slab.h>
30 #include <linux/uaccess.h>
31 #include <linux/init.h>
32 #include <linux/netfilter_ipv4.h>
33 #include <linux/if_ether.h>
34 
35 #include <net/sock.h>
36 #include <net/snmp.h>
37 
38 #include <net/ipv6.h>
39 #include <net/protocol.h>
40 #include <net/transp_v6.h>
41 #include <net/ip6_fib.h>
42 #include <net/ip6_route.h>
43 #include <net/ndisc.h>
44 #include <net/addrconf.h>
45 #include <net/ip.h>
46 #include <net/udp.h>
47 #include <net/icmp.h>
48 #include <net/ip_tunnels.h>
49 #include <net/inet_ecn.h>
50 #include <net/xfrm.h>
51 #include <net/dsfield.h>
52 #include <net/net_namespace.h>
53 #include <net/netns/generic.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 IP6_SIT_HASH_SIZE  16
62 #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
63 
64 static bool log_ecn_error = true;
65 module_param(log_ecn_error, bool, 0644);
66 MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
67 
68 static int ipip6_tunnel_init(struct net_device *dev);
69 static void ipip6_tunnel_setup(struct net_device *dev);
70 static void ipip6_dev_free(struct net_device *dev);
71 static bool check_6rd(struct ip_tunnel *tunnel, const struct in6_addr *v6dst,
72 		      __be32 *v4dst);
73 static struct rtnl_link_ops sit_link_ops __read_mostly;
74 
75 static unsigned int sit_net_id __read_mostly;
76 struct sit_net {
77 	struct ip_tunnel __rcu *tunnels_r_l[IP6_SIT_HASH_SIZE];
78 	struct ip_tunnel __rcu *tunnels_r[IP6_SIT_HASH_SIZE];
79 	struct ip_tunnel __rcu *tunnels_l[IP6_SIT_HASH_SIZE];
80 	struct ip_tunnel __rcu *tunnels_wc[1];
81 	struct ip_tunnel __rcu **tunnels[4];
82 
83 	struct net_device *fb_tunnel_dev;
84 };
85 
86 static inline struct sit_net *dev_to_sit_net(struct net_device *dev)
87 {
88 	struct ip_tunnel *t = netdev_priv(dev);
89 
90 	return net_generic(t->net, sit_net_id);
91 }
92 
93 /*
94  * Must be invoked with rcu_read_lock
95  */
96 static struct ip_tunnel *ipip6_tunnel_lookup(struct net *net,
97 					     struct net_device *dev,
98 					     __be32 remote, __be32 local,
99 					     int sifindex)
100 {
101 	unsigned int h0 = HASH(remote);
102 	unsigned int h1 = HASH(local);
103 	struct ip_tunnel *t;
104 	struct sit_net *sitn = net_generic(net, sit_net_id);
105 	int ifindex = dev ? dev->ifindex : 0;
106 
107 	for_each_ip_tunnel_rcu(t, sitn->tunnels_r_l[h0 ^ h1]) {
108 		if (local == t->parms.iph.saddr &&
109 		    remote == t->parms.iph.daddr &&
110 		    (!dev || !t->parms.link || ifindex == t->parms.link ||
111 		     sifindex == t->parms.link) &&
112 		    (t->dev->flags & IFF_UP))
113 			return t;
114 	}
115 	for_each_ip_tunnel_rcu(t, sitn->tunnels_r[h0]) {
116 		if (remote == t->parms.iph.daddr &&
117 		    (!dev || !t->parms.link || ifindex == t->parms.link ||
118 		     sifindex == t->parms.link) &&
119 		    (t->dev->flags & IFF_UP))
120 			return t;
121 	}
122 	for_each_ip_tunnel_rcu(t, sitn->tunnels_l[h1]) {
123 		if (local == t->parms.iph.saddr &&
124 		    (!dev || !t->parms.link || ifindex == t->parms.link ||
125 		     sifindex == t->parms.link) &&
126 		    (t->dev->flags & IFF_UP))
127 			return t;
128 	}
129 	t = rcu_dereference(sitn->tunnels_wc[0]);
130 	if (t && (t->dev->flags & IFF_UP))
131 		return t;
132 	return NULL;
133 }
134 
135 static struct ip_tunnel __rcu **__ipip6_bucket(struct sit_net *sitn,
136 		struct ip_tunnel_parm *parms)
137 {
138 	__be32 remote = parms->iph.daddr;
139 	__be32 local = parms->iph.saddr;
140 	unsigned int h = 0;
141 	int prio = 0;
142 
143 	if (remote) {
144 		prio |= 2;
145 		h ^= HASH(remote);
146 	}
147 	if (local) {
148 		prio |= 1;
149 		h ^= HASH(local);
150 	}
151 	return &sitn->tunnels[prio][h];
152 }
153 
154 static inline struct ip_tunnel __rcu **ipip6_bucket(struct sit_net *sitn,
155 		struct ip_tunnel *t)
156 {
157 	return __ipip6_bucket(sitn, &t->parms);
158 }
159 
160 static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
161 {
162 	struct ip_tunnel __rcu **tp;
163 	struct ip_tunnel *iter;
164 
165 	for (tp = ipip6_bucket(sitn, t);
166 	     (iter = rtnl_dereference(*tp)) != NULL;
167 	     tp = &iter->next) {
168 		if (t == iter) {
169 			rcu_assign_pointer(*tp, t->next);
170 			break;
171 		}
172 	}
173 }
174 
175 static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
176 {
177 	struct ip_tunnel __rcu **tp = ipip6_bucket(sitn, t);
178 
179 	rcu_assign_pointer(t->next, rtnl_dereference(*tp));
180 	rcu_assign_pointer(*tp, t);
181 }
182 
183 static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
184 {
185 #ifdef CONFIG_IPV6_SIT_6RD
186 	struct ip_tunnel *t = netdev_priv(dev);
187 
188 	if (dev == sitn->fb_tunnel_dev || !sitn->fb_tunnel_dev) {
189 		ipv6_addr_set(&t->ip6rd.prefix, htonl(0x20020000), 0, 0, 0);
190 		t->ip6rd.relay_prefix = 0;
191 		t->ip6rd.prefixlen = 16;
192 		t->ip6rd.relay_prefixlen = 0;
193 	} else {
194 		struct ip_tunnel *t0 = netdev_priv(sitn->fb_tunnel_dev);
195 		memcpy(&t->ip6rd, &t0->ip6rd, sizeof(t->ip6rd));
196 	}
197 #endif
198 }
199 
200 static int ipip6_tunnel_create(struct net_device *dev)
201 {
202 	struct ip_tunnel *t = netdev_priv(dev);
203 	struct net *net = dev_net(dev);
204 	struct sit_net *sitn = net_generic(net, sit_net_id);
205 	int err;
206 
207 	__dev_addr_set(dev, &t->parms.iph.saddr, 4);
208 	memcpy(dev->broadcast, &t->parms.iph.daddr, 4);
209 
210 	if ((__force u16)t->parms.i_flags & SIT_ISATAP)
211 		dev->priv_flags |= IFF_ISATAP;
212 
213 	dev->rtnl_link_ops = &sit_link_ops;
214 
215 	err = register_netdevice(dev);
216 	if (err < 0)
217 		goto out;
218 
219 	ipip6_tunnel_clone_6rd(dev, sitn);
220 
221 	ipip6_tunnel_link(sitn, t);
222 	return 0;
223 
224 out:
225 	return err;
226 }
227 
228 static struct ip_tunnel *ipip6_tunnel_locate(struct net *net,
229 		struct ip_tunnel_parm *parms, int create)
230 {
231 	__be32 remote = parms->iph.daddr;
232 	__be32 local = parms->iph.saddr;
233 	struct ip_tunnel *t, *nt;
234 	struct ip_tunnel __rcu **tp;
235 	struct net_device *dev;
236 	char name[IFNAMSIZ];
237 	struct sit_net *sitn = net_generic(net, sit_net_id);
238 
239 	for (tp = __ipip6_bucket(sitn, parms);
240 	    (t = rtnl_dereference(*tp)) != NULL;
241 	     tp = &t->next) {
242 		if (local == t->parms.iph.saddr &&
243 		    remote == t->parms.iph.daddr &&
244 		    parms->link == t->parms.link) {
245 			if (create)
246 				return NULL;
247 			else
248 				return t;
249 		}
250 	}
251 	if (!create)
252 		goto failed;
253 
254 	if (parms->name[0]) {
255 		if (!dev_valid_name(parms->name))
256 			goto failed;
257 		strscpy(name, parms->name, IFNAMSIZ);
258 	} else {
259 		strcpy(name, "sit%d");
260 	}
261 	dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
262 			   ipip6_tunnel_setup);
263 	if (!dev)
264 		return NULL;
265 
266 	dev_net_set(dev, net);
267 
268 	nt = netdev_priv(dev);
269 
270 	nt->parms = *parms;
271 	if (ipip6_tunnel_create(dev) < 0)
272 		goto failed_free;
273 
274 	if (!parms->name[0])
275 		strcpy(parms->name, dev->name);
276 
277 	return nt;
278 
279 failed_free:
280 	free_netdev(dev);
281 failed:
282 	return NULL;
283 }
284 
285 #define for_each_prl_rcu(start)			\
286 	for (prl = rcu_dereference(start);	\
287 	     prl;				\
288 	     prl = rcu_dereference(prl->next))
289 
290 static struct ip_tunnel_prl_entry *
291 __ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
292 {
293 	struct ip_tunnel_prl_entry *prl;
294 
295 	for_each_prl_rcu(t->prl)
296 		if (prl->addr == addr)
297 			break;
298 	return prl;
299 
300 }
301 
302 static int ipip6_tunnel_get_prl(struct net_device *dev, struct ip_tunnel_prl __user *a)
303 {
304 	struct ip_tunnel *t = netdev_priv(dev);
305 	struct ip_tunnel_prl kprl, *kp;
306 	struct ip_tunnel_prl_entry *prl;
307 	unsigned int cmax, c = 0, ca, len;
308 	int ret = 0;
309 
310 	if (dev == dev_to_sit_net(dev)->fb_tunnel_dev)
311 		return -EINVAL;
312 
313 	if (copy_from_user(&kprl, a, sizeof(kprl)))
314 		return -EFAULT;
315 	cmax = kprl.datalen / sizeof(kprl);
316 	if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
317 		cmax = 1;
318 
319 	/* For simple GET or for root users,
320 	 * we try harder to allocate.
321 	 */
322 	kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
323 		kcalloc(cmax, sizeof(*kp), GFP_KERNEL_ACCOUNT | __GFP_NOWARN) :
324 		NULL;
325 
326 	ca = min(t->prl_count, cmax);
327 
328 	if (!kp) {
329 		/* We don't try hard to allocate much memory for
330 		 * non-root users.
331 		 * For root users, retry allocating enough memory for
332 		 * the answer.
333 		 */
334 		kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC | __GFP_ACCOUNT |
335 					      __GFP_NOWARN);
336 		if (!kp) {
337 			ret = -ENOMEM;
338 			goto out;
339 		}
340 	}
341 
342 	rcu_read_lock();
343 	for_each_prl_rcu(t->prl) {
344 		if (c >= cmax)
345 			break;
346 		if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
347 			continue;
348 		kp[c].addr = prl->addr;
349 		kp[c].flags = prl->flags;
350 		c++;
351 		if (kprl.addr != htonl(INADDR_ANY))
352 			break;
353 	}
354 
355 	rcu_read_unlock();
356 
357 	len = sizeof(*kp) * c;
358 	ret = 0;
359 	if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
360 		ret = -EFAULT;
361 
362 	kfree(kp);
363 out:
364 	return ret;
365 }
366 
367 static int
368 ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
369 {
370 	struct ip_tunnel_prl_entry *p;
371 	int err = 0;
372 
373 	if (a->addr == htonl(INADDR_ANY))
374 		return -EINVAL;
375 
376 	ASSERT_RTNL();
377 
378 	for (p = rtnl_dereference(t->prl); p; p = rtnl_dereference(p->next)) {
379 		if (p->addr == a->addr) {
380 			if (chg) {
381 				p->flags = a->flags;
382 				goto out;
383 			}
384 			err = -EEXIST;
385 			goto out;
386 		}
387 	}
388 
389 	if (chg) {
390 		err = -ENXIO;
391 		goto out;
392 	}
393 
394 	p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
395 	if (!p) {
396 		err = -ENOBUFS;
397 		goto out;
398 	}
399 
400 	p->next = t->prl;
401 	p->addr = a->addr;
402 	p->flags = a->flags;
403 	t->prl_count++;
404 	rcu_assign_pointer(t->prl, p);
405 out:
406 	return err;
407 }
408 
409 static void prl_list_destroy_rcu(struct rcu_head *head)
410 {
411 	struct ip_tunnel_prl_entry *p, *n;
412 
413 	p = container_of(head, struct ip_tunnel_prl_entry, rcu_head);
414 	do {
415 		n = rcu_dereference_protected(p->next, 1);
416 		kfree(p);
417 		p = n;
418 	} while (p);
419 }
420 
421 static int
422 ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
423 {
424 	struct ip_tunnel_prl_entry *x;
425 	struct ip_tunnel_prl_entry __rcu **p;
426 	int err = 0;
427 
428 	ASSERT_RTNL();
429 
430 	if (a && a->addr != htonl(INADDR_ANY)) {
431 		for (p = &t->prl;
432 		     (x = rtnl_dereference(*p)) != NULL;
433 		     p = &x->next) {
434 			if (x->addr == a->addr) {
435 				*p = x->next;
436 				kfree_rcu(x, rcu_head);
437 				t->prl_count--;
438 				goto out;
439 			}
440 		}
441 		err = -ENXIO;
442 	} else {
443 		x = rtnl_dereference(t->prl);
444 		if (x) {
445 			t->prl_count = 0;
446 			call_rcu(&x->rcu_head, prl_list_destroy_rcu);
447 			t->prl = NULL;
448 		}
449 	}
450 out:
451 	return err;
452 }
453 
454 static int ipip6_tunnel_prl_ctl(struct net_device *dev,
455 				struct ip_tunnel_prl __user *data, int cmd)
456 {
457 	struct ip_tunnel *t = netdev_priv(dev);
458 	struct ip_tunnel_prl prl;
459 	int err;
460 
461 	if (!ns_capable(t->net->user_ns, CAP_NET_ADMIN))
462 		return -EPERM;
463 	if (dev == dev_to_sit_net(dev)->fb_tunnel_dev)
464 		return -EINVAL;
465 
466 	if (copy_from_user(&prl, data, sizeof(prl)))
467 		return -EFAULT;
468 
469 	switch (cmd) {
470 	case SIOCDELPRL:
471 		err = ipip6_tunnel_del_prl(t, &prl);
472 		break;
473 	case SIOCADDPRL:
474 	case SIOCCHGPRL:
475 		err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
476 		break;
477 	}
478 	dst_cache_reset(&t->dst_cache);
479 	netdev_state_change(dev);
480 	return err;
481 }
482 
483 static int
484 isatap_chksrc(struct sk_buff *skb, const struct iphdr *iph, struct ip_tunnel *t)
485 {
486 	struct ip_tunnel_prl_entry *p;
487 	int ok = 1;
488 
489 	rcu_read_lock();
490 	p = __ipip6_tunnel_locate_prl(t, iph->saddr);
491 	if (p) {
492 		if (p->flags & PRL_DEFAULT)
493 			skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
494 		else
495 			skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
496 	} else {
497 		const struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
498 
499 		if (ipv6_addr_is_isatap(addr6) &&
500 		    (addr6->s6_addr32[3] == iph->saddr) &&
501 		    ipv6_chk_prefix(addr6, t->dev))
502 			skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
503 		else
504 			ok = 0;
505 	}
506 	rcu_read_unlock();
507 	return ok;
508 }
509 
510 static void ipip6_tunnel_uninit(struct net_device *dev)
511 {
512 	struct ip_tunnel *tunnel = netdev_priv(dev);
513 	struct sit_net *sitn = net_generic(tunnel->net, sit_net_id);
514 
515 	if (dev == sitn->fb_tunnel_dev) {
516 		RCU_INIT_POINTER(sitn->tunnels_wc[0], NULL);
517 	} else {
518 		ipip6_tunnel_unlink(sitn, tunnel);
519 		ipip6_tunnel_del_prl(tunnel, NULL);
520 	}
521 	dst_cache_reset(&tunnel->dst_cache);
522 	netdev_put(dev, &tunnel->dev_tracker);
523 }
524 
525 static int ipip6_err(struct sk_buff *skb, u32 info)
526 {
527 	const struct iphdr *iph = (const struct iphdr *)skb->data;
528 	const int type = icmp_hdr(skb)->type;
529 	const int code = icmp_hdr(skb)->code;
530 	unsigned int data_len = 0;
531 	struct ip_tunnel *t;
532 	int sifindex;
533 	int err;
534 
535 	switch (type) {
536 	default:
537 	case ICMP_PARAMETERPROB:
538 		return 0;
539 
540 	case ICMP_DEST_UNREACH:
541 		switch (code) {
542 		case ICMP_SR_FAILED:
543 			/* Impossible event. */
544 			return 0;
545 		default:
546 			/* All others are translated to HOST_UNREACH.
547 			   rfc2003 contains "deep thoughts" about NET_UNREACH,
548 			   I believe they are just ether pollution. --ANK
549 			 */
550 			break;
551 		}
552 		break;
553 	case ICMP_TIME_EXCEEDED:
554 		if (code != ICMP_EXC_TTL)
555 			return 0;
556 		data_len = icmp_hdr(skb)->un.reserved[1] * 4; /* RFC 4884 4.1 */
557 		break;
558 	case ICMP_REDIRECT:
559 		break;
560 	}
561 
562 	err = -ENOENT;
563 
564 	sifindex = netif_is_l3_master(skb->dev) ? IPCB(skb)->iif : 0;
565 	t = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
566 				iph->daddr, iph->saddr, sifindex);
567 	if (!t)
568 		goto out;
569 
570 	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
571 		ipv4_update_pmtu(skb, dev_net(skb->dev), info,
572 				 t->parms.link, iph->protocol);
573 		err = 0;
574 		goto out;
575 	}
576 	if (type == ICMP_REDIRECT) {
577 		ipv4_redirect(skb, dev_net(skb->dev), t->parms.link,
578 			      iph->protocol);
579 		err = 0;
580 		goto out;
581 	}
582 
583 	err = 0;
584 	if (__in6_dev_get(skb->dev) &&
585 	    !ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4, type, data_len))
586 		goto out;
587 
588 	if (t->parms.iph.daddr == 0)
589 		goto out;
590 
591 	if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
592 		goto out;
593 
594 	if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
595 		t->err_count++;
596 	else
597 		t->err_count = 1;
598 	t->err_time = jiffies;
599 out:
600 	return err;
601 }
602 
603 static inline bool is_spoofed_6rd(struct ip_tunnel *tunnel, const __be32 v4addr,
604 				  const struct in6_addr *v6addr)
605 {
606 	__be32 v4embed = 0;
607 	if (check_6rd(tunnel, v6addr, &v4embed) && v4addr != v4embed)
608 		return true;
609 	return false;
610 }
611 
612 /* Checks if an address matches an address on the tunnel interface.
613  * Used to detect the NAT of proto 41 packets and let them pass spoofing test.
614  * Long story:
615  * This function is called after we considered the packet as spoofed
616  * in is_spoofed_6rd.
617  * We may have a router that is doing NAT for proto 41 packets
618  * for an internal station. Destination a.a.a.a/PREFIX:bbbb:bbbb
619  * will be translated to n.n.n.n/PREFIX:bbbb:bbbb. And is_spoofed_6rd
620  * function will return true, dropping the packet.
621  * But, we can still check if is spoofed against the IP
622  * addresses associated with the interface.
623  */
624 static bool only_dnatted(const struct ip_tunnel *tunnel,
625 	const struct in6_addr *v6dst)
626 {
627 	int prefix_len;
628 
629 #ifdef CONFIG_IPV6_SIT_6RD
630 	prefix_len = tunnel->ip6rd.prefixlen + 32
631 		- tunnel->ip6rd.relay_prefixlen;
632 #else
633 	prefix_len = 48;
634 #endif
635 	return ipv6_chk_custom_prefix(v6dst, prefix_len, tunnel->dev);
636 }
637 
638 /* Returns true if a packet is spoofed */
639 static bool packet_is_spoofed(struct sk_buff *skb,
640 			      const struct iphdr *iph,
641 			      struct ip_tunnel *tunnel)
642 {
643 	const struct ipv6hdr *ipv6h;
644 
645 	if (tunnel->dev->priv_flags & IFF_ISATAP) {
646 		if (!isatap_chksrc(skb, iph, tunnel))
647 			return true;
648 
649 		return false;
650 	}
651 
652 	if (tunnel->dev->flags & IFF_POINTOPOINT)
653 		return false;
654 
655 	ipv6h = ipv6_hdr(skb);
656 
657 	if (unlikely(is_spoofed_6rd(tunnel, iph->saddr, &ipv6h->saddr))) {
658 		net_warn_ratelimited("Src spoofed %pI4/%pI6c -> %pI4/%pI6c\n",
659 				     &iph->saddr, &ipv6h->saddr,
660 				     &iph->daddr, &ipv6h->daddr);
661 		return true;
662 	}
663 
664 	if (likely(!is_spoofed_6rd(tunnel, iph->daddr, &ipv6h->daddr)))
665 		return false;
666 
667 	if (only_dnatted(tunnel, &ipv6h->daddr))
668 		return false;
669 
670 	net_warn_ratelimited("Dst spoofed %pI4/%pI6c -> %pI4/%pI6c\n",
671 			     &iph->saddr, &ipv6h->saddr,
672 			     &iph->daddr, &ipv6h->daddr);
673 	return true;
674 }
675 
676 static int ipip6_rcv(struct sk_buff *skb)
677 {
678 	const struct iphdr *iph = ip_hdr(skb);
679 	struct ip_tunnel *tunnel;
680 	int sifindex;
681 	int err;
682 
683 	sifindex = netif_is_l3_master(skb->dev) ? IPCB(skb)->iif : 0;
684 	tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
685 				     iph->saddr, iph->daddr, sifindex);
686 	if (tunnel) {
687 		if (tunnel->parms.iph.protocol != IPPROTO_IPV6 &&
688 		    tunnel->parms.iph.protocol != 0)
689 			goto out;
690 
691 		skb->mac_header = skb->network_header;
692 		skb_reset_network_header(skb);
693 		IPCB(skb)->flags = 0;
694 		skb->dev = tunnel->dev;
695 
696 		if (packet_is_spoofed(skb, iph, tunnel)) {
697 			DEV_STATS_INC(tunnel->dev, rx_errors);
698 			goto out;
699 		}
700 
701 		if (iptunnel_pull_header(skb, 0, htons(ETH_P_IPV6),
702 		    !net_eq(tunnel->net, dev_net(tunnel->dev))))
703 			goto out;
704 
705 		/* skb can be uncloned in iptunnel_pull_header, so
706 		 * old iph is no longer valid
707 		 */
708 		iph = (const struct iphdr *)skb_mac_header(skb);
709 		skb_reset_mac_header(skb);
710 
711 		err = IP_ECN_decapsulate(iph, skb);
712 		if (unlikely(err)) {
713 			if (log_ecn_error)
714 				net_info_ratelimited("non-ECT from %pI4 with TOS=%#x\n",
715 						     &iph->saddr, iph->tos);
716 			if (err > 1) {
717 				DEV_STATS_INC(tunnel->dev, rx_frame_errors);
718 				DEV_STATS_INC(tunnel->dev, rx_errors);
719 				goto out;
720 			}
721 		}
722 
723 		dev_sw_netstats_rx_add(tunnel->dev, skb->len);
724 
725 		netif_rx(skb);
726 
727 		return 0;
728 	}
729 
730 	/* no tunnel matched,  let upstream know, ipsec may handle it */
731 	return 1;
732 out:
733 	kfree_skb(skb);
734 	return 0;
735 }
736 
737 static const struct tnl_ptk_info ipip_tpi = {
738 	/* no tunnel info required for ipip. */
739 	.proto = htons(ETH_P_IP),
740 };
741 
742 #if IS_ENABLED(CONFIG_MPLS)
743 static const struct tnl_ptk_info mplsip_tpi = {
744 	/* no tunnel info required for mplsip. */
745 	.proto = htons(ETH_P_MPLS_UC),
746 };
747 #endif
748 
749 static int sit_tunnel_rcv(struct sk_buff *skb, u8 ipproto)
750 {
751 	const struct iphdr *iph;
752 	struct ip_tunnel *tunnel;
753 	int sifindex;
754 
755 	sifindex = netif_is_l3_master(skb->dev) ? IPCB(skb)->iif : 0;
756 
757 	iph = ip_hdr(skb);
758 	tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
759 				     iph->saddr, iph->daddr, sifindex);
760 	if (tunnel) {
761 		const struct tnl_ptk_info *tpi;
762 
763 		if (tunnel->parms.iph.protocol != ipproto &&
764 		    tunnel->parms.iph.protocol != 0)
765 			goto drop;
766 
767 		if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
768 			goto drop;
769 #if IS_ENABLED(CONFIG_MPLS)
770 		if (ipproto == IPPROTO_MPLS)
771 			tpi = &mplsip_tpi;
772 		else
773 #endif
774 			tpi = &ipip_tpi;
775 		if (iptunnel_pull_header(skb, 0, tpi->proto, false))
776 			goto drop;
777 		skb_reset_mac_header(skb);
778 
779 		return ip_tunnel_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
780 	}
781 
782 	return 1;
783 
784 drop:
785 	kfree_skb(skb);
786 	return 0;
787 }
788 
789 static int ipip_rcv(struct sk_buff *skb)
790 {
791 	return sit_tunnel_rcv(skb, IPPROTO_IPIP);
792 }
793 
794 #if IS_ENABLED(CONFIG_MPLS)
795 static int mplsip_rcv(struct sk_buff *skb)
796 {
797 	return sit_tunnel_rcv(skb, IPPROTO_MPLS);
798 }
799 #endif
800 
801 /*
802  * If the IPv6 address comes from 6rd / 6to4 (RFC 3056) addr space this function
803  * stores the embedded IPv4 address in v4dst and returns true.
804  */
805 static bool check_6rd(struct ip_tunnel *tunnel, const struct in6_addr *v6dst,
806 		      __be32 *v4dst)
807 {
808 #ifdef CONFIG_IPV6_SIT_6RD
809 	if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
810 			      tunnel->ip6rd.prefixlen)) {
811 		unsigned int pbw0, pbi0;
812 		int pbi1;
813 		u32 d;
814 
815 		pbw0 = tunnel->ip6rd.prefixlen >> 5;
816 		pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
817 
818 		d = tunnel->ip6rd.relay_prefixlen < 32 ?
819 			(ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
820 		    tunnel->ip6rd.relay_prefixlen : 0;
821 
822 		pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
823 		if (pbi1 > 0)
824 			d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
825 			     (32 - pbi1);
826 
827 		*v4dst = tunnel->ip6rd.relay_prefix | htonl(d);
828 		return true;
829 	}
830 #else
831 	if (v6dst->s6_addr16[0] == htons(0x2002)) {
832 		/* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
833 		memcpy(v4dst, &v6dst->s6_addr16[1], 4);
834 		return true;
835 	}
836 #endif
837 	return false;
838 }
839 
840 static inline __be32 try_6rd(struct ip_tunnel *tunnel,
841 			     const struct in6_addr *v6dst)
842 {
843 	__be32 dst = 0;
844 	check_6rd(tunnel, v6dst, &dst);
845 	return dst;
846 }
847 
848 /*
849  *	This function assumes it is being called from dev_queue_xmit()
850  *	and that skb is filled properly by that function.
851  */
852 
853 static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
854 				     struct net_device *dev)
855 {
856 	struct ip_tunnel *tunnel = netdev_priv(dev);
857 	const struct iphdr  *tiph = &tunnel->parms.iph;
858 	const struct ipv6hdr *iph6 = ipv6_hdr(skb);
859 	u8     tos = tunnel->parms.iph.tos;
860 	__be16 df = tiph->frag_off;
861 	struct rtable *rt;		/* Route to the other host */
862 	struct net_device *tdev;	/* Device to other host */
863 	unsigned int max_headroom;	/* The extra header space needed */
864 	__be32 dst = tiph->daddr;
865 	struct flowi4 fl4;
866 	int    mtu;
867 	const struct in6_addr *addr6;
868 	int addr_type;
869 	u8 ttl;
870 	u8 protocol = IPPROTO_IPV6;
871 	int t_hlen = tunnel->hlen + sizeof(struct iphdr);
872 
873 	if (tos == 1)
874 		tos = ipv6_get_dsfield(iph6);
875 
876 	/* ISATAP (RFC4214) - must come before 6to4 */
877 	if (dev->priv_flags & IFF_ISATAP) {
878 		struct neighbour *neigh = NULL;
879 		bool do_tx_error = false;
880 
881 		if (skb_dst(skb))
882 			neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);
883 
884 		if (!neigh) {
885 			net_dbg_ratelimited("nexthop == NULL\n");
886 			goto tx_error;
887 		}
888 
889 		addr6 = (const struct in6_addr *)&neigh->primary_key;
890 		addr_type = ipv6_addr_type(addr6);
891 
892 		if ((addr_type & IPV6_ADDR_UNICAST) &&
893 		     ipv6_addr_is_isatap(addr6))
894 			dst = addr6->s6_addr32[3];
895 		else
896 			do_tx_error = true;
897 
898 		neigh_release(neigh);
899 		if (do_tx_error)
900 			goto tx_error;
901 	}
902 
903 	if (!dst)
904 		dst = try_6rd(tunnel, &iph6->daddr);
905 
906 	if (!dst) {
907 		struct neighbour *neigh = NULL;
908 		bool do_tx_error = false;
909 
910 		if (skb_dst(skb))
911 			neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);
912 
913 		if (!neigh) {
914 			net_dbg_ratelimited("nexthop == NULL\n");
915 			goto tx_error;
916 		}
917 
918 		addr6 = (const struct in6_addr *)&neigh->primary_key;
919 		addr_type = ipv6_addr_type(addr6);
920 
921 		if (addr_type == IPV6_ADDR_ANY) {
922 			addr6 = &ipv6_hdr(skb)->daddr;
923 			addr_type = ipv6_addr_type(addr6);
924 		}
925 
926 		if ((addr_type & IPV6_ADDR_COMPATv4) != 0)
927 			dst = addr6->s6_addr32[3];
928 		else
929 			do_tx_error = true;
930 
931 		neigh_release(neigh);
932 		if (do_tx_error)
933 			goto tx_error;
934 	}
935 
936 	flowi4_init_output(&fl4, tunnel->parms.link, tunnel->fwmark,
937 			   RT_TOS(tos), RT_SCOPE_UNIVERSE, IPPROTO_IPV6,
938 			   0, dst, tiph->saddr, 0, 0,
939 			   sock_net_uid(tunnel->net, NULL));
940 
941 	rt = dst_cache_get_ip4(&tunnel->dst_cache, &fl4.saddr);
942 	if (!rt) {
943 		rt = ip_route_output_flow(tunnel->net, &fl4, NULL);
944 		if (IS_ERR(rt)) {
945 			DEV_STATS_INC(dev, tx_carrier_errors);
946 			goto tx_error_icmp;
947 		}
948 		dst_cache_set_ip4(&tunnel->dst_cache, &rt->dst, fl4.saddr);
949 	}
950 
951 	if (rt->rt_type != RTN_UNICAST && rt->rt_type != RTN_LOCAL) {
952 		ip_rt_put(rt);
953 		DEV_STATS_INC(dev, tx_carrier_errors);
954 		goto tx_error_icmp;
955 	}
956 	tdev = rt->dst.dev;
957 
958 	if (tdev == dev) {
959 		ip_rt_put(rt);
960 		DEV_STATS_INC(dev, collisions);
961 		goto tx_error;
962 	}
963 
964 	if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP4)) {
965 		ip_rt_put(rt);
966 		goto tx_error;
967 	}
968 
969 	if (df) {
970 		mtu = dst_mtu(&rt->dst) - t_hlen;
971 
972 		if (mtu < IPV4_MIN_MTU) {
973 			DEV_STATS_INC(dev, collisions);
974 			ip_rt_put(rt);
975 			goto tx_error;
976 		}
977 
978 		if (mtu < IPV6_MIN_MTU) {
979 			mtu = IPV6_MIN_MTU;
980 			df = 0;
981 		}
982 
983 		if (tunnel->parms.iph.daddr)
984 			skb_dst_update_pmtu_no_confirm(skb, mtu);
985 
986 		if (skb->len > mtu && !skb_is_gso(skb)) {
987 			icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
988 			ip_rt_put(rt);
989 			goto tx_error;
990 		}
991 	}
992 
993 	if (tunnel->err_count > 0) {
994 		if (time_before(jiffies,
995 				tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
996 			tunnel->err_count--;
997 			dst_link_failure(skb);
998 		} else
999 			tunnel->err_count = 0;
1000 	}
1001 
1002 	/*
1003 	 * Okay, now see if we can stuff it in the buffer as-is.
1004 	 */
1005 	max_headroom = LL_RESERVED_SPACE(tdev) + t_hlen;
1006 
1007 	if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
1008 	    (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
1009 		struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
1010 		if (!new_skb) {
1011 			ip_rt_put(rt);
1012 			DEV_STATS_INC(dev, tx_dropped);
1013 			kfree_skb(skb);
1014 			return NETDEV_TX_OK;
1015 		}
1016 		if (skb->sk)
1017 			skb_set_owner_w(new_skb, skb->sk);
1018 		dev_kfree_skb(skb);
1019 		skb = new_skb;
1020 		iph6 = ipv6_hdr(skb);
1021 	}
1022 	ttl = tiph->ttl;
1023 	if (ttl == 0)
1024 		ttl = iph6->hop_limit;
1025 	tos = INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
1026 
1027 	if (ip_tunnel_encap(skb, &tunnel->encap, &protocol, &fl4) < 0) {
1028 		ip_rt_put(rt);
1029 		goto tx_error;
1030 	}
1031 
1032 	skb_set_inner_ipproto(skb, IPPROTO_IPV6);
1033 
1034 	iptunnel_xmit(NULL, rt, skb, fl4.saddr, fl4.daddr, protocol, tos, ttl,
1035 		      df, !net_eq(tunnel->net, dev_net(dev)));
1036 	return NETDEV_TX_OK;
1037 
1038 tx_error_icmp:
1039 	dst_link_failure(skb);
1040 tx_error:
1041 	kfree_skb(skb);
1042 	DEV_STATS_INC(dev, tx_errors);
1043 	return NETDEV_TX_OK;
1044 }
1045 
1046 static netdev_tx_t sit_tunnel_xmit__(struct sk_buff *skb,
1047 				     struct net_device *dev, u8 ipproto)
1048 {
1049 	struct ip_tunnel *tunnel = netdev_priv(dev);
1050 	const struct iphdr  *tiph = &tunnel->parms.iph;
1051 
1052 	if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP4))
1053 		goto tx_error;
1054 
1055 	skb_set_inner_ipproto(skb, ipproto);
1056 
1057 	ip_tunnel_xmit(skb, dev, tiph, ipproto);
1058 	return NETDEV_TX_OK;
1059 tx_error:
1060 	kfree_skb(skb);
1061 	DEV_STATS_INC(dev, tx_errors);
1062 	return NETDEV_TX_OK;
1063 }
1064 
1065 static netdev_tx_t sit_tunnel_xmit(struct sk_buff *skb,
1066 				   struct net_device *dev)
1067 {
1068 	if (!pskb_inet_may_pull(skb))
1069 		goto tx_err;
1070 
1071 	switch (skb->protocol) {
1072 	case htons(ETH_P_IP):
1073 		sit_tunnel_xmit__(skb, dev, IPPROTO_IPIP);
1074 		break;
1075 	case htons(ETH_P_IPV6):
1076 		ipip6_tunnel_xmit(skb, dev);
1077 		break;
1078 #if IS_ENABLED(CONFIG_MPLS)
1079 	case htons(ETH_P_MPLS_UC):
1080 		sit_tunnel_xmit__(skb, dev, IPPROTO_MPLS);
1081 		break;
1082 #endif
1083 	default:
1084 		goto tx_err;
1085 	}
1086 
1087 	return NETDEV_TX_OK;
1088 
1089 tx_err:
1090 	DEV_STATS_INC(dev, tx_errors);
1091 	kfree_skb(skb);
1092 	return NETDEV_TX_OK;
1093 
1094 }
1095 
1096 static void ipip6_tunnel_bind_dev(struct net_device *dev)
1097 {
1098 	struct ip_tunnel *tunnel = netdev_priv(dev);
1099 	int t_hlen = tunnel->hlen + sizeof(struct iphdr);
1100 	struct net_device *tdev = NULL;
1101 	int hlen = LL_MAX_HEADER;
1102 	const struct iphdr *iph;
1103 	struct flowi4 fl4;
1104 
1105 	iph = &tunnel->parms.iph;
1106 
1107 	if (iph->daddr) {
1108 		struct rtable *rt = ip_route_output_ports(tunnel->net, &fl4,
1109 							  NULL,
1110 							  iph->daddr, iph->saddr,
1111 							  0, 0,
1112 							  IPPROTO_IPV6,
1113 							  RT_TOS(iph->tos),
1114 							  tunnel->parms.link);
1115 
1116 		if (!IS_ERR(rt)) {
1117 			tdev = rt->dst.dev;
1118 			ip_rt_put(rt);
1119 		}
1120 		dev->flags |= IFF_POINTOPOINT;
1121 	}
1122 
1123 	if (!tdev && tunnel->parms.link)
1124 		tdev = __dev_get_by_index(tunnel->net, tunnel->parms.link);
1125 
1126 	if (tdev && !netif_is_l3_master(tdev)) {
1127 		int mtu;
1128 
1129 		mtu = tdev->mtu - t_hlen;
1130 		if (mtu < IPV6_MIN_MTU)
1131 			mtu = IPV6_MIN_MTU;
1132 		WRITE_ONCE(dev->mtu, mtu);
1133 		hlen = tdev->hard_header_len + tdev->needed_headroom;
1134 	}
1135 	dev->needed_headroom = t_hlen + hlen;
1136 }
1137 
1138 static void ipip6_tunnel_update(struct ip_tunnel *t, struct ip_tunnel_parm *p,
1139 				__u32 fwmark)
1140 {
1141 	struct net *net = t->net;
1142 	struct sit_net *sitn = net_generic(net, sit_net_id);
1143 
1144 	ipip6_tunnel_unlink(sitn, t);
1145 	synchronize_net();
1146 	t->parms.iph.saddr = p->iph.saddr;
1147 	t->parms.iph.daddr = p->iph.daddr;
1148 	__dev_addr_set(t->dev, &p->iph.saddr, 4);
1149 	memcpy(t->dev->broadcast, &p->iph.daddr, 4);
1150 	ipip6_tunnel_link(sitn, t);
1151 	t->parms.iph.ttl = p->iph.ttl;
1152 	t->parms.iph.tos = p->iph.tos;
1153 	t->parms.iph.frag_off = p->iph.frag_off;
1154 	if (t->parms.link != p->link || t->fwmark != fwmark) {
1155 		t->parms.link = p->link;
1156 		t->fwmark = fwmark;
1157 		ipip6_tunnel_bind_dev(t->dev);
1158 	}
1159 	dst_cache_reset(&t->dst_cache);
1160 	netdev_state_change(t->dev);
1161 }
1162 
1163 #ifdef CONFIG_IPV6_SIT_6RD
1164 static int ipip6_tunnel_update_6rd(struct ip_tunnel *t,
1165 				   struct ip_tunnel_6rd *ip6rd)
1166 {
1167 	struct in6_addr prefix;
1168 	__be32 relay_prefix;
1169 
1170 	if (ip6rd->relay_prefixlen > 32 ||
1171 	    ip6rd->prefixlen + (32 - ip6rd->relay_prefixlen) > 64)
1172 		return -EINVAL;
1173 
1174 	ipv6_addr_prefix(&prefix, &ip6rd->prefix, ip6rd->prefixlen);
1175 	if (!ipv6_addr_equal(&prefix, &ip6rd->prefix))
1176 		return -EINVAL;
1177 	if (ip6rd->relay_prefixlen)
1178 		relay_prefix = ip6rd->relay_prefix &
1179 			       htonl(0xffffffffUL <<
1180 				     (32 - ip6rd->relay_prefixlen));
1181 	else
1182 		relay_prefix = 0;
1183 	if (relay_prefix != ip6rd->relay_prefix)
1184 		return -EINVAL;
1185 
1186 	t->ip6rd.prefix = prefix;
1187 	t->ip6rd.relay_prefix = relay_prefix;
1188 	t->ip6rd.prefixlen = ip6rd->prefixlen;
1189 	t->ip6rd.relay_prefixlen = ip6rd->relay_prefixlen;
1190 	dst_cache_reset(&t->dst_cache);
1191 	netdev_state_change(t->dev);
1192 	return 0;
1193 }
1194 
1195 static int
1196 ipip6_tunnel_get6rd(struct net_device *dev, struct ip_tunnel_parm __user *data)
1197 {
1198 	struct ip_tunnel *t = netdev_priv(dev);
1199 	struct ip_tunnel_6rd ip6rd;
1200 	struct ip_tunnel_parm p;
1201 
1202 	if (dev == dev_to_sit_net(dev)->fb_tunnel_dev) {
1203 		if (copy_from_user(&p, data, sizeof(p)))
1204 			return -EFAULT;
1205 		t = ipip6_tunnel_locate(t->net, &p, 0);
1206 	}
1207 	if (!t)
1208 		t = netdev_priv(dev);
1209 
1210 	ip6rd.prefix = t->ip6rd.prefix;
1211 	ip6rd.relay_prefix = t->ip6rd.relay_prefix;
1212 	ip6rd.prefixlen = t->ip6rd.prefixlen;
1213 	ip6rd.relay_prefixlen = t->ip6rd.relay_prefixlen;
1214 	if (copy_to_user(data, &ip6rd, sizeof(ip6rd)))
1215 		return -EFAULT;
1216 	return 0;
1217 }
1218 
1219 static int
1220 ipip6_tunnel_6rdctl(struct net_device *dev, struct ip_tunnel_6rd __user *data,
1221 		    int cmd)
1222 {
1223 	struct ip_tunnel *t = netdev_priv(dev);
1224 	struct ip_tunnel_6rd ip6rd;
1225 	int err;
1226 
1227 	if (!ns_capable(t->net->user_ns, CAP_NET_ADMIN))
1228 		return -EPERM;
1229 	if (copy_from_user(&ip6rd, data, sizeof(ip6rd)))
1230 		return -EFAULT;
1231 
1232 	if (cmd != SIOCDEL6RD) {
1233 		err = ipip6_tunnel_update_6rd(t, &ip6rd);
1234 		if (err < 0)
1235 			return err;
1236 	} else
1237 		ipip6_tunnel_clone_6rd(dev, dev_to_sit_net(dev));
1238 	return 0;
1239 }
1240 
1241 #endif /* CONFIG_IPV6_SIT_6RD */
1242 
1243 static bool ipip6_valid_ip_proto(u8 ipproto)
1244 {
1245 	return ipproto == IPPROTO_IPV6 ||
1246 		ipproto == IPPROTO_IPIP ||
1247 #if IS_ENABLED(CONFIG_MPLS)
1248 		ipproto == IPPROTO_MPLS ||
1249 #endif
1250 		ipproto == 0;
1251 }
1252 
1253 static int
1254 __ipip6_tunnel_ioctl_validate(struct net *net, struct ip_tunnel_parm *p)
1255 {
1256 	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
1257 		return -EPERM;
1258 
1259 	if (!ipip6_valid_ip_proto(p->iph.protocol))
1260 		return -EINVAL;
1261 	if (p->iph.version != 4 ||
1262 	    p->iph.ihl != 5 || (p->iph.frag_off & htons(~IP_DF)))
1263 		return -EINVAL;
1264 
1265 	if (p->iph.ttl)
1266 		p->iph.frag_off |= htons(IP_DF);
1267 	return 0;
1268 }
1269 
1270 static int
1271 ipip6_tunnel_get(struct net_device *dev, struct ip_tunnel_parm *p)
1272 {
1273 	struct ip_tunnel *t = netdev_priv(dev);
1274 
1275 	if (dev == dev_to_sit_net(dev)->fb_tunnel_dev)
1276 		t = ipip6_tunnel_locate(t->net, p, 0);
1277 	if (!t)
1278 		t = netdev_priv(dev);
1279 	memcpy(p, &t->parms, sizeof(*p));
1280 	return 0;
1281 }
1282 
1283 static int
1284 ipip6_tunnel_add(struct net_device *dev, struct ip_tunnel_parm *p)
1285 {
1286 	struct ip_tunnel *t = netdev_priv(dev);
1287 	int err;
1288 
1289 	err = __ipip6_tunnel_ioctl_validate(t->net, p);
1290 	if (err)
1291 		return err;
1292 
1293 	t = ipip6_tunnel_locate(t->net, p, 1);
1294 	if (!t)
1295 		return -ENOBUFS;
1296 	return 0;
1297 }
1298 
1299 static int
1300 ipip6_tunnel_change(struct net_device *dev, struct ip_tunnel_parm *p)
1301 {
1302 	struct ip_tunnel *t = netdev_priv(dev);
1303 	int err;
1304 
1305 	err = __ipip6_tunnel_ioctl_validate(t->net, p);
1306 	if (err)
1307 		return err;
1308 
1309 	t = ipip6_tunnel_locate(t->net, p, 0);
1310 	if (dev == dev_to_sit_net(dev)->fb_tunnel_dev) {
1311 		if (!t)
1312 			return -ENOENT;
1313 	} else {
1314 		if (t) {
1315 			if (t->dev != dev)
1316 				return -EEXIST;
1317 		} else {
1318 			if (((dev->flags & IFF_POINTOPOINT) && !p->iph.daddr) ||
1319 			    (!(dev->flags & IFF_POINTOPOINT) && p->iph.daddr))
1320 				return -EINVAL;
1321 			t = netdev_priv(dev);
1322 		}
1323 
1324 		ipip6_tunnel_update(t, p, t->fwmark);
1325 	}
1326 
1327 	return 0;
1328 }
1329 
1330 static int
1331 ipip6_tunnel_del(struct net_device *dev, struct ip_tunnel_parm *p)
1332 {
1333 	struct ip_tunnel *t = netdev_priv(dev);
1334 
1335 	if (!ns_capable(t->net->user_ns, CAP_NET_ADMIN))
1336 		return -EPERM;
1337 
1338 	if (dev == dev_to_sit_net(dev)->fb_tunnel_dev) {
1339 		t = ipip6_tunnel_locate(t->net, p, 0);
1340 		if (!t)
1341 			return -ENOENT;
1342 		if (t == netdev_priv(dev_to_sit_net(dev)->fb_tunnel_dev))
1343 			return -EPERM;
1344 		dev = t->dev;
1345 	}
1346 	unregister_netdevice(dev);
1347 	return 0;
1348 }
1349 
1350 static int
1351 ipip6_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd)
1352 {
1353 	switch (cmd) {
1354 	case SIOCGETTUNNEL:
1355 		return ipip6_tunnel_get(dev, p);
1356 	case SIOCADDTUNNEL:
1357 		return ipip6_tunnel_add(dev, p);
1358 	case SIOCCHGTUNNEL:
1359 		return ipip6_tunnel_change(dev, p);
1360 	case SIOCDELTUNNEL:
1361 		return ipip6_tunnel_del(dev, p);
1362 	default:
1363 		return -EINVAL;
1364 	}
1365 }
1366 
1367 static int
1368 ipip6_tunnel_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
1369 			    void __user *data, int cmd)
1370 {
1371 	switch (cmd) {
1372 	case SIOCGETTUNNEL:
1373 	case SIOCADDTUNNEL:
1374 	case SIOCCHGTUNNEL:
1375 	case SIOCDELTUNNEL:
1376 		return ip_tunnel_siocdevprivate(dev, ifr, data, cmd);
1377 	case SIOCGETPRL:
1378 		return ipip6_tunnel_get_prl(dev, data);
1379 	case SIOCADDPRL:
1380 	case SIOCDELPRL:
1381 	case SIOCCHGPRL:
1382 		return ipip6_tunnel_prl_ctl(dev, data, cmd);
1383 #ifdef CONFIG_IPV6_SIT_6RD
1384 	case SIOCGET6RD:
1385 		return ipip6_tunnel_get6rd(dev, data);
1386 	case SIOCADD6RD:
1387 	case SIOCCHG6RD:
1388 	case SIOCDEL6RD:
1389 		return ipip6_tunnel_6rdctl(dev, data, cmd);
1390 #endif
1391 	default:
1392 		return -EINVAL;
1393 	}
1394 }
1395 
1396 static const struct net_device_ops ipip6_netdev_ops = {
1397 	.ndo_init	= ipip6_tunnel_init,
1398 	.ndo_uninit	= ipip6_tunnel_uninit,
1399 	.ndo_start_xmit	= sit_tunnel_xmit,
1400 	.ndo_siocdevprivate = ipip6_tunnel_siocdevprivate,
1401 	.ndo_get_stats64 = dev_get_tstats64,
1402 	.ndo_get_iflink = ip_tunnel_get_iflink,
1403 	.ndo_tunnel_ctl = ipip6_tunnel_ctl,
1404 };
1405 
1406 static void ipip6_dev_free(struct net_device *dev)
1407 {
1408 	struct ip_tunnel *tunnel = netdev_priv(dev);
1409 
1410 	dst_cache_destroy(&tunnel->dst_cache);
1411 	free_percpu(dev->tstats);
1412 }
1413 
1414 #define SIT_FEATURES (NETIF_F_SG	   | \
1415 		      NETIF_F_FRAGLIST	   | \
1416 		      NETIF_F_HIGHDMA	   | \
1417 		      NETIF_F_GSO_SOFTWARE | \
1418 		      NETIF_F_HW_CSUM)
1419 
1420 static void ipip6_tunnel_setup(struct net_device *dev)
1421 {
1422 	struct ip_tunnel *tunnel = netdev_priv(dev);
1423 	int t_hlen = tunnel->hlen + sizeof(struct iphdr);
1424 
1425 	dev->netdev_ops		= &ipip6_netdev_ops;
1426 	dev->header_ops		= &ip_tunnel_header_ops;
1427 	dev->needs_free_netdev	= true;
1428 	dev->priv_destructor	= ipip6_dev_free;
1429 
1430 	dev->type		= ARPHRD_SIT;
1431 	dev->mtu		= ETH_DATA_LEN - t_hlen;
1432 	dev->min_mtu		= IPV6_MIN_MTU;
1433 	dev->max_mtu		= IP6_MAX_MTU - t_hlen;
1434 	dev->flags		= IFF_NOARP;
1435 	netif_keep_dst(dev);
1436 	dev->addr_len		= 4;
1437 	dev->features		|= NETIF_F_LLTX;
1438 	dev->features		|= SIT_FEATURES;
1439 	dev->hw_features	|= SIT_FEATURES;
1440 }
1441 
1442 static int ipip6_tunnel_init(struct net_device *dev)
1443 {
1444 	struct ip_tunnel *tunnel = netdev_priv(dev);
1445 	int err;
1446 
1447 	tunnel->dev = dev;
1448 	tunnel->net = dev_net(dev);
1449 	strcpy(tunnel->parms.name, dev->name);
1450 
1451 	ipip6_tunnel_bind_dev(dev);
1452 	dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
1453 	if (!dev->tstats)
1454 		return -ENOMEM;
1455 
1456 	err = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);
1457 	if (err) {
1458 		free_percpu(dev->tstats);
1459 		dev->tstats = NULL;
1460 		return err;
1461 	}
1462 	netdev_hold(dev, &tunnel->dev_tracker, GFP_KERNEL);
1463 	return 0;
1464 }
1465 
1466 static void __net_init ipip6_fb_tunnel_init(struct net_device *dev)
1467 {
1468 	struct ip_tunnel *tunnel = netdev_priv(dev);
1469 	struct iphdr *iph = &tunnel->parms.iph;
1470 	struct net *net = dev_net(dev);
1471 	struct sit_net *sitn = net_generic(net, sit_net_id);
1472 
1473 	iph->version		= 4;
1474 	iph->protocol		= IPPROTO_IPV6;
1475 	iph->ihl		= 5;
1476 	iph->ttl		= 64;
1477 
1478 	rcu_assign_pointer(sitn->tunnels_wc[0], tunnel);
1479 }
1480 
1481 static int ipip6_validate(struct nlattr *tb[], struct nlattr *data[],
1482 			  struct netlink_ext_ack *extack)
1483 {
1484 	u8 proto;
1485 
1486 	if (!data || !data[IFLA_IPTUN_PROTO])
1487 		return 0;
1488 
1489 	proto = nla_get_u8(data[IFLA_IPTUN_PROTO]);
1490 	if (!ipip6_valid_ip_proto(proto))
1491 		return -EINVAL;
1492 
1493 	return 0;
1494 }
1495 
1496 static void ipip6_netlink_parms(struct nlattr *data[],
1497 				struct ip_tunnel_parm *parms,
1498 				__u32 *fwmark)
1499 {
1500 	memset(parms, 0, sizeof(*parms));
1501 
1502 	parms->iph.version = 4;
1503 	parms->iph.protocol = IPPROTO_IPV6;
1504 	parms->iph.ihl = 5;
1505 	parms->iph.ttl = 64;
1506 
1507 	if (!data)
1508 		return;
1509 
1510 	ip_tunnel_netlink_parms(data, parms);
1511 
1512 	if (data[IFLA_IPTUN_FWMARK])
1513 		*fwmark = nla_get_u32(data[IFLA_IPTUN_FWMARK]);
1514 }
1515 
1516 #ifdef CONFIG_IPV6_SIT_6RD
1517 /* This function returns true when 6RD attributes are present in the nl msg */
1518 static bool ipip6_netlink_6rd_parms(struct nlattr *data[],
1519 				    struct ip_tunnel_6rd *ip6rd)
1520 {
1521 	bool ret = false;
1522 	memset(ip6rd, 0, sizeof(*ip6rd));
1523 
1524 	if (!data)
1525 		return ret;
1526 
1527 	if (data[IFLA_IPTUN_6RD_PREFIX]) {
1528 		ret = true;
1529 		ip6rd->prefix = nla_get_in6_addr(data[IFLA_IPTUN_6RD_PREFIX]);
1530 	}
1531 
1532 	if (data[IFLA_IPTUN_6RD_RELAY_PREFIX]) {
1533 		ret = true;
1534 		ip6rd->relay_prefix =
1535 			nla_get_be32(data[IFLA_IPTUN_6RD_RELAY_PREFIX]);
1536 	}
1537 
1538 	if (data[IFLA_IPTUN_6RD_PREFIXLEN]) {
1539 		ret = true;
1540 		ip6rd->prefixlen = nla_get_u16(data[IFLA_IPTUN_6RD_PREFIXLEN]);
1541 	}
1542 
1543 	if (data[IFLA_IPTUN_6RD_RELAY_PREFIXLEN]) {
1544 		ret = true;
1545 		ip6rd->relay_prefixlen =
1546 			nla_get_u16(data[IFLA_IPTUN_6RD_RELAY_PREFIXLEN]);
1547 	}
1548 
1549 	return ret;
1550 }
1551 #endif
1552 
1553 static int ipip6_newlink(struct net *src_net, struct net_device *dev,
1554 			 struct nlattr *tb[], struct nlattr *data[],
1555 			 struct netlink_ext_ack *extack)
1556 {
1557 	struct net *net = dev_net(dev);
1558 	struct ip_tunnel *nt;
1559 	struct ip_tunnel_encap ipencap;
1560 #ifdef CONFIG_IPV6_SIT_6RD
1561 	struct ip_tunnel_6rd ip6rd;
1562 #endif
1563 	int err;
1564 
1565 	nt = netdev_priv(dev);
1566 
1567 	if (ip_tunnel_netlink_encap_parms(data, &ipencap)) {
1568 		err = ip_tunnel_encap_setup(nt, &ipencap);
1569 		if (err < 0)
1570 			return err;
1571 	}
1572 
1573 	ipip6_netlink_parms(data, &nt->parms, &nt->fwmark);
1574 
1575 	if (ipip6_tunnel_locate(net, &nt->parms, 0))
1576 		return -EEXIST;
1577 
1578 	err = ipip6_tunnel_create(dev);
1579 	if (err < 0)
1580 		return err;
1581 
1582 	if (tb[IFLA_MTU]) {
1583 		u32 mtu = nla_get_u32(tb[IFLA_MTU]);
1584 
1585 		if (mtu >= IPV6_MIN_MTU &&
1586 		    mtu <= IP6_MAX_MTU - dev->hard_header_len)
1587 			dev->mtu = mtu;
1588 	}
1589 
1590 #ifdef CONFIG_IPV6_SIT_6RD
1591 	if (ipip6_netlink_6rd_parms(data, &ip6rd)) {
1592 		err = ipip6_tunnel_update_6rd(nt, &ip6rd);
1593 		if (err < 0)
1594 			unregister_netdevice_queue(dev, NULL);
1595 	}
1596 #endif
1597 
1598 	return err;
1599 }
1600 
1601 static int ipip6_changelink(struct net_device *dev, struct nlattr *tb[],
1602 			    struct nlattr *data[],
1603 			    struct netlink_ext_ack *extack)
1604 {
1605 	struct ip_tunnel *t = netdev_priv(dev);
1606 	struct ip_tunnel_parm p;
1607 	struct ip_tunnel_encap ipencap;
1608 	struct net *net = t->net;
1609 	struct sit_net *sitn = net_generic(net, sit_net_id);
1610 #ifdef CONFIG_IPV6_SIT_6RD
1611 	struct ip_tunnel_6rd ip6rd;
1612 #endif
1613 	__u32 fwmark = t->fwmark;
1614 	int err;
1615 
1616 	if (dev == sitn->fb_tunnel_dev)
1617 		return -EINVAL;
1618 
1619 	if (ip_tunnel_netlink_encap_parms(data, &ipencap)) {
1620 		err = ip_tunnel_encap_setup(t, &ipencap);
1621 		if (err < 0)
1622 			return err;
1623 	}
1624 
1625 	ipip6_netlink_parms(data, &p, &fwmark);
1626 
1627 	if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) ||
1628 	    (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr))
1629 		return -EINVAL;
1630 
1631 	t = ipip6_tunnel_locate(net, &p, 0);
1632 
1633 	if (t) {
1634 		if (t->dev != dev)
1635 			return -EEXIST;
1636 	} else
1637 		t = netdev_priv(dev);
1638 
1639 	ipip6_tunnel_update(t, &p, fwmark);
1640 
1641 #ifdef CONFIG_IPV6_SIT_6RD
1642 	if (ipip6_netlink_6rd_parms(data, &ip6rd))
1643 		return ipip6_tunnel_update_6rd(t, &ip6rd);
1644 #endif
1645 
1646 	return 0;
1647 }
1648 
1649 static size_t ipip6_get_size(const struct net_device *dev)
1650 {
1651 	return
1652 		/* IFLA_IPTUN_LINK */
1653 		nla_total_size(4) +
1654 		/* IFLA_IPTUN_LOCAL */
1655 		nla_total_size(4) +
1656 		/* IFLA_IPTUN_REMOTE */
1657 		nla_total_size(4) +
1658 		/* IFLA_IPTUN_TTL */
1659 		nla_total_size(1) +
1660 		/* IFLA_IPTUN_TOS */
1661 		nla_total_size(1) +
1662 		/* IFLA_IPTUN_PMTUDISC */
1663 		nla_total_size(1) +
1664 		/* IFLA_IPTUN_FLAGS */
1665 		nla_total_size(2) +
1666 		/* IFLA_IPTUN_PROTO */
1667 		nla_total_size(1) +
1668 #ifdef CONFIG_IPV6_SIT_6RD
1669 		/* IFLA_IPTUN_6RD_PREFIX */
1670 		nla_total_size(sizeof(struct in6_addr)) +
1671 		/* IFLA_IPTUN_6RD_RELAY_PREFIX */
1672 		nla_total_size(4) +
1673 		/* IFLA_IPTUN_6RD_PREFIXLEN */
1674 		nla_total_size(2) +
1675 		/* IFLA_IPTUN_6RD_RELAY_PREFIXLEN */
1676 		nla_total_size(2) +
1677 #endif
1678 		/* IFLA_IPTUN_ENCAP_TYPE */
1679 		nla_total_size(2) +
1680 		/* IFLA_IPTUN_ENCAP_FLAGS */
1681 		nla_total_size(2) +
1682 		/* IFLA_IPTUN_ENCAP_SPORT */
1683 		nla_total_size(2) +
1684 		/* IFLA_IPTUN_ENCAP_DPORT */
1685 		nla_total_size(2) +
1686 		/* IFLA_IPTUN_FWMARK */
1687 		nla_total_size(4) +
1688 		0;
1689 }
1690 
1691 static int ipip6_fill_info(struct sk_buff *skb, const struct net_device *dev)
1692 {
1693 	struct ip_tunnel *tunnel = netdev_priv(dev);
1694 	struct ip_tunnel_parm *parm = &tunnel->parms;
1695 
1696 	if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) ||
1697 	    nla_put_in_addr(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) ||
1698 	    nla_put_in_addr(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) ||
1699 	    nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) ||
1700 	    nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) ||
1701 	    nla_put_u8(skb, IFLA_IPTUN_PMTUDISC,
1702 		       !!(parm->iph.frag_off & htons(IP_DF))) ||
1703 	    nla_put_u8(skb, IFLA_IPTUN_PROTO, parm->iph.protocol) ||
1704 	    nla_put_be16(skb, IFLA_IPTUN_FLAGS, parm->i_flags) ||
1705 	    nla_put_u32(skb, IFLA_IPTUN_FWMARK, tunnel->fwmark))
1706 		goto nla_put_failure;
1707 
1708 #ifdef CONFIG_IPV6_SIT_6RD
1709 	if (nla_put_in6_addr(skb, IFLA_IPTUN_6RD_PREFIX,
1710 			     &tunnel->ip6rd.prefix) ||
1711 	    nla_put_in_addr(skb, IFLA_IPTUN_6RD_RELAY_PREFIX,
1712 			    tunnel->ip6rd.relay_prefix) ||
1713 	    nla_put_u16(skb, IFLA_IPTUN_6RD_PREFIXLEN,
1714 			tunnel->ip6rd.prefixlen) ||
1715 	    nla_put_u16(skb, IFLA_IPTUN_6RD_RELAY_PREFIXLEN,
1716 			tunnel->ip6rd.relay_prefixlen))
1717 		goto nla_put_failure;
1718 #endif
1719 
1720 	if (nla_put_u16(skb, IFLA_IPTUN_ENCAP_TYPE,
1721 			tunnel->encap.type) ||
1722 	    nla_put_be16(skb, IFLA_IPTUN_ENCAP_SPORT,
1723 			tunnel->encap.sport) ||
1724 	    nla_put_be16(skb, IFLA_IPTUN_ENCAP_DPORT,
1725 			tunnel->encap.dport) ||
1726 	    nla_put_u16(skb, IFLA_IPTUN_ENCAP_FLAGS,
1727 			tunnel->encap.flags))
1728 		goto nla_put_failure;
1729 
1730 	return 0;
1731 
1732 nla_put_failure:
1733 	return -EMSGSIZE;
1734 }
1735 
1736 static const struct nla_policy ipip6_policy[IFLA_IPTUN_MAX + 1] = {
1737 	[IFLA_IPTUN_LINK]		= { .type = NLA_U32 },
1738 	[IFLA_IPTUN_LOCAL]		= { .type = NLA_U32 },
1739 	[IFLA_IPTUN_REMOTE]		= { .type = NLA_U32 },
1740 	[IFLA_IPTUN_TTL]		= { .type = NLA_U8 },
1741 	[IFLA_IPTUN_TOS]		= { .type = NLA_U8 },
1742 	[IFLA_IPTUN_PMTUDISC]		= { .type = NLA_U8 },
1743 	[IFLA_IPTUN_FLAGS]		= { .type = NLA_U16 },
1744 	[IFLA_IPTUN_PROTO]		= { .type = NLA_U8 },
1745 #ifdef CONFIG_IPV6_SIT_6RD
1746 	[IFLA_IPTUN_6RD_PREFIX]		= { .len = sizeof(struct in6_addr) },
1747 	[IFLA_IPTUN_6RD_RELAY_PREFIX]	= { .type = NLA_U32 },
1748 	[IFLA_IPTUN_6RD_PREFIXLEN]	= { .type = NLA_U16 },
1749 	[IFLA_IPTUN_6RD_RELAY_PREFIXLEN] = { .type = NLA_U16 },
1750 #endif
1751 	[IFLA_IPTUN_ENCAP_TYPE]		= { .type = NLA_U16 },
1752 	[IFLA_IPTUN_ENCAP_FLAGS]	= { .type = NLA_U16 },
1753 	[IFLA_IPTUN_ENCAP_SPORT]	= { .type = NLA_U16 },
1754 	[IFLA_IPTUN_ENCAP_DPORT]	= { .type = NLA_U16 },
1755 	[IFLA_IPTUN_FWMARK]		= { .type = NLA_U32 },
1756 };
1757 
1758 static void ipip6_dellink(struct net_device *dev, struct list_head *head)
1759 {
1760 	struct net *net = dev_net(dev);
1761 	struct sit_net *sitn = net_generic(net, sit_net_id);
1762 
1763 	if (dev != sitn->fb_tunnel_dev)
1764 		unregister_netdevice_queue(dev, head);
1765 }
1766 
1767 static struct rtnl_link_ops sit_link_ops __read_mostly = {
1768 	.kind		= "sit",
1769 	.maxtype	= IFLA_IPTUN_MAX,
1770 	.policy		= ipip6_policy,
1771 	.priv_size	= sizeof(struct ip_tunnel),
1772 	.setup		= ipip6_tunnel_setup,
1773 	.validate	= ipip6_validate,
1774 	.newlink	= ipip6_newlink,
1775 	.changelink	= ipip6_changelink,
1776 	.get_size	= ipip6_get_size,
1777 	.fill_info	= ipip6_fill_info,
1778 	.dellink	= ipip6_dellink,
1779 	.get_link_net	= ip_tunnel_get_link_net,
1780 };
1781 
1782 static struct xfrm_tunnel sit_handler __read_mostly = {
1783 	.handler	=	ipip6_rcv,
1784 	.err_handler	=	ipip6_err,
1785 	.priority	=	1,
1786 };
1787 
1788 static struct xfrm_tunnel ipip_handler __read_mostly = {
1789 	.handler	=	ipip_rcv,
1790 	.err_handler	=	ipip6_err,
1791 	.priority	=	2,
1792 };
1793 
1794 #if IS_ENABLED(CONFIG_MPLS)
1795 static struct xfrm_tunnel mplsip_handler __read_mostly = {
1796 	.handler	=	mplsip_rcv,
1797 	.err_handler	=	ipip6_err,
1798 	.priority	=	2,
1799 };
1800 #endif
1801 
1802 static void __net_exit sit_destroy_tunnels(struct net *net,
1803 					   struct list_head *head)
1804 {
1805 	struct sit_net *sitn = net_generic(net, sit_net_id);
1806 	struct net_device *dev, *aux;
1807 	int prio;
1808 
1809 	for_each_netdev_safe(net, dev, aux)
1810 		if (dev->rtnl_link_ops == &sit_link_ops)
1811 			unregister_netdevice_queue(dev, head);
1812 
1813 	for (prio = 0; prio < 4; prio++) {
1814 		int h;
1815 		for (h = 0; h < (prio ? IP6_SIT_HASH_SIZE : 1); h++) {
1816 			struct ip_tunnel *t;
1817 
1818 			t = rtnl_dereference(sitn->tunnels[prio][h]);
1819 			while (t) {
1820 				/* If dev is in the same netns, it has already
1821 				 * been added to the list by the previous loop.
1822 				 */
1823 				if (!net_eq(dev_net(t->dev), net))
1824 					unregister_netdevice_queue(t->dev,
1825 								   head);
1826 				t = rtnl_dereference(t->next);
1827 			}
1828 		}
1829 	}
1830 }
1831 
1832 static int __net_init sit_init_net(struct net *net)
1833 {
1834 	struct sit_net *sitn = net_generic(net, sit_net_id);
1835 	struct ip_tunnel *t;
1836 	int err;
1837 
1838 	sitn->tunnels[0] = sitn->tunnels_wc;
1839 	sitn->tunnels[1] = sitn->tunnels_l;
1840 	sitn->tunnels[2] = sitn->tunnels_r;
1841 	sitn->tunnels[3] = sitn->tunnels_r_l;
1842 
1843 	if (!net_has_fallback_tunnels(net))
1844 		return 0;
1845 
1846 	sitn->fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "sit0",
1847 					   NET_NAME_UNKNOWN,
1848 					   ipip6_tunnel_setup);
1849 	if (!sitn->fb_tunnel_dev) {
1850 		err = -ENOMEM;
1851 		goto err_alloc_dev;
1852 	}
1853 	dev_net_set(sitn->fb_tunnel_dev, net);
1854 	sitn->fb_tunnel_dev->rtnl_link_ops = &sit_link_ops;
1855 	/* FB netdevice is special: we have one, and only one per netns.
1856 	 * Allowing to move it to another netns is clearly unsafe.
1857 	 */
1858 	sitn->fb_tunnel_dev->features |= NETIF_F_NETNS_LOCAL;
1859 
1860 	err = register_netdev(sitn->fb_tunnel_dev);
1861 	if (err)
1862 		goto err_reg_dev;
1863 
1864 	ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
1865 	ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
1866 
1867 	t = netdev_priv(sitn->fb_tunnel_dev);
1868 
1869 	strcpy(t->parms.name, sitn->fb_tunnel_dev->name);
1870 	return 0;
1871 
1872 err_reg_dev:
1873 	free_netdev(sitn->fb_tunnel_dev);
1874 err_alloc_dev:
1875 	return err;
1876 }
1877 
1878 static void __net_exit sit_exit_batch_net(struct list_head *net_list)
1879 {
1880 	LIST_HEAD(list);
1881 	struct net *net;
1882 
1883 	rtnl_lock();
1884 	list_for_each_entry(net, net_list, exit_list)
1885 		sit_destroy_tunnels(net, &list);
1886 
1887 	unregister_netdevice_many(&list);
1888 	rtnl_unlock();
1889 }
1890 
1891 static struct pernet_operations sit_net_ops = {
1892 	.init = sit_init_net,
1893 	.exit_batch = sit_exit_batch_net,
1894 	.id   = &sit_net_id,
1895 	.size = sizeof(struct sit_net),
1896 };
1897 
1898 static void __exit sit_cleanup(void)
1899 {
1900 	rtnl_link_unregister(&sit_link_ops);
1901 	xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1902 	xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
1903 #if IS_ENABLED(CONFIG_MPLS)
1904 	xfrm4_tunnel_deregister(&mplsip_handler, AF_MPLS);
1905 #endif
1906 
1907 	unregister_pernet_device(&sit_net_ops);
1908 	rcu_barrier(); /* Wait for completion of call_rcu()'s */
1909 }
1910 
1911 static int __init sit_init(void)
1912 {
1913 	int err;
1914 
1915 	pr_info("IPv6, IPv4 and MPLS over IPv4 tunneling driver\n");
1916 
1917 	err = register_pernet_device(&sit_net_ops);
1918 	if (err < 0)
1919 		return err;
1920 	err = xfrm4_tunnel_register(&sit_handler, AF_INET6);
1921 	if (err < 0) {
1922 		pr_info("%s: can't register ip6ip4\n", __func__);
1923 		goto xfrm_tunnel_failed;
1924 	}
1925 	err = xfrm4_tunnel_register(&ipip_handler, AF_INET);
1926 	if (err < 0) {
1927 		pr_info("%s: can't register ip4ip4\n", __func__);
1928 		goto xfrm_tunnel4_failed;
1929 	}
1930 #if IS_ENABLED(CONFIG_MPLS)
1931 	err = xfrm4_tunnel_register(&mplsip_handler, AF_MPLS);
1932 	if (err < 0) {
1933 		pr_info("%s: can't register mplsip\n", __func__);
1934 		goto xfrm_tunnel_mpls_failed;
1935 	}
1936 #endif
1937 	err = rtnl_link_register(&sit_link_ops);
1938 	if (err < 0)
1939 		goto rtnl_link_failed;
1940 
1941 out:
1942 	return err;
1943 
1944 rtnl_link_failed:
1945 #if IS_ENABLED(CONFIG_MPLS)
1946 	xfrm4_tunnel_deregister(&mplsip_handler, AF_MPLS);
1947 xfrm_tunnel_mpls_failed:
1948 #endif
1949 	xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
1950 xfrm_tunnel4_failed:
1951 	xfrm4_tunnel_deregister(&sit_handler, AF_INET6);
1952 xfrm_tunnel_failed:
1953 	unregister_pernet_device(&sit_net_ops);
1954 	goto out;
1955 }
1956 
1957 module_init(sit_init);
1958 module_exit(sit_cleanup);
1959 MODULE_DESCRIPTION("IPv6-in-IPv4 tunnel SIT driver");
1960 MODULE_LICENSE("GPL");
1961 MODULE_ALIAS_RTNL_LINK("sit");
1962 MODULE_ALIAS_NETDEV("sit0");
1963