[ARM] Support register switch in nommu mode
[linux-2.6/verdex.git] / net / ipv4 / ip_gre.c
blobabe23923e4e73975bd6ae486a7ef1c8ce89fb2a9
1 /*
2 * Linux NET3: GRE over IP protocol decoder.
4 * Authors: Alexey Kuznetsov (kuznet@ms2.inr.ac.ru)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
13 #include <linux/capability.h>
14 #include <linux/config.h>
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <linux/sched.h>
18 #include <linux/kernel.h>
19 #include <asm/uaccess.h>
20 #include <linux/skbuff.h>
21 #include <linux/netdevice.h>
22 #include <linux/in.h>
23 #include <linux/tcp.h>
24 #include <linux/udp.h>
25 #include <linux/if_arp.h>
26 #include <linux/mroute.h>
27 #include <linux/init.h>
28 #include <linux/in6.h>
29 #include <linux/inetdevice.h>
30 #include <linux/igmp.h>
31 #include <linux/netfilter_ipv4.h>
32 #include <linux/if_ether.h>
34 #include <net/sock.h>
35 #include <net/ip.h>
36 #include <net/icmp.h>
37 #include <net/protocol.h>
38 #include <net/ipip.h>
39 #include <net/arp.h>
40 #include <net/checksum.h>
41 #include <net/dsfield.h>
42 #include <net/inet_ecn.h>
43 #include <net/xfrm.h>
45 #ifdef CONFIG_IPV6
46 #include <net/ipv6.h>
47 #include <net/ip6_fib.h>
48 #include <net/ip6_route.h>
49 #endif
52 Problems & solutions
53 --------------------
55 1. The most important issue is detecting local dead loops.
56 They would cause complete host lockup in transmit, which
57 would be "resolved" by stack overflow or, if queueing is enabled,
58 with infinite looping in net_bh.
60 We cannot track such dead loops during route installation,
61 it is infeasible task. The most general solutions would be
62 to keep skb->encapsulation counter (sort of local ttl),
63 and silently drop packet when it expires. It is the best
64 solution, but it supposes maintaing new variable in ALL
65 skb, even if no tunneling is used.
67 Current solution: t->recursion lock breaks dead loops. It looks
68 like dev->tbusy flag, but I preferred new variable, because
69 the semantics is different. One day, when hard_start_xmit
70 will be multithreaded we will have to use skb->encapsulation.
74 2. Networking dead loops would not kill routers, but would really
75 kill network. IP hop limit plays role of "t->recursion" in this case,
76 if we copy it from packet being encapsulated to upper header.
77 It is very good solution, but it introduces two problems:
79 - Routing protocols, using packets with ttl=1 (OSPF, RIP2),
80 do not work over tunnels.
81 - traceroute does not work. I planned to relay ICMP from tunnel,
82 so that this problem would be solved and traceroute output
83 would even more informative. This idea appeared to be wrong:
84 only Linux complies to rfc1812 now (yes, guys, Linux is the only
85 true router now :-)), all routers (at least, in neighbourhood of mine)
86 return only 8 bytes of payload. It is the end.
88 Hence, if we want that OSPF worked or traceroute said something reasonable,
89 we should search for another solution.
91 One of them is to parse packet trying to detect inner encapsulation
92 made by our node. It is difficult or even impossible, especially,
93 taking into account fragmentation. TO be short, tt is not solution at all.
95 Current solution: The solution was UNEXPECTEDLY SIMPLE.
96 We force DF flag on tunnels with preconfigured hop limit,
97 that is ALL. :-) Well, it does not remove the problem completely,
98 but exponential growth of network traffic is changed to linear
99 (branches, that exceed pmtu are pruned) and tunnel mtu
100 fastly degrades to value <68, where looping stops.
101 Yes, it is not good if there exists a router in the loop,
102 which does not force DF, even when encapsulating packets have DF set.
103 But it is not our problem! Nobody could accuse us, we made
104 all that we could make. Even if it is your gated who injected
105 fatal route to network, even if it were you who configured
106 fatal static route: you are innocent. :-)
110 3. Really, ipv4/ipip.c, ipv4/ip_gre.c and ipv6/sit.c contain
111 practically identical code. It would be good to glue them
112 together, but it is not very evident, how to make them modular.
113 sit is integral part of IPv6, ipip and gre are naturally modular.
114 We could extract common parts (hash table, ioctl etc)
115 to a separate module (ip_tunnel.c).
117 Alexey Kuznetsov.
120 static int ipgre_tunnel_init(struct net_device *dev);
121 static void ipgre_tunnel_setup(struct net_device *dev);
123 /* Fallback tunnel: no source, no destination, no key, no options */
125 static int ipgre_fb_tunnel_init(struct net_device *dev);
127 static struct net_device *ipgre_fb_tunnel_dev;
129 /* Tunnel hash table */
132 4 hash tables:
134 3: (remote,local)
135 2: (remote,*)
136 1: (*,local)
137 0: (*,*)
139 We require exact key match i.e. if a key is present in packet
140 it will match only tunnel with the same key; if it is not present,
141 it will match only keyless tunnel.
143 All keysless packets, if not matched configured keyless tunnels
144 will match fallback tunnel.
147 #define HASH_SIZE 16
148 #define HASH(addr) ((addr^(addr>>4))&0xF)
150 static struct ip_tunnel *tunnels[4][HASH_SIZE];
152 #define tunnels_r_l (tunnels[3])
153 #define tunnels_r (tunnels[2])
154 #define tunnels_l (tunnels[1])
155 #define tunnels_wc (tunnels[0])
157 static DEFINE_RWLOCK(ipgre_lock);
159 /* Given src, dst and key, find appropriate for input tunnel. */
161 static struct ip_tunnel * ipgre_tunnel_lookup(u32 remote, u32 local, u32 key)
163 unsigned h0 = HASH(remote);
164 unsigned h1 = HASH(key);
165 struct ip_tunnel *t;
167 for (t = tunnels_r_l[h0^h1]; t; t = t->next) {
168 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
169 if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
170 return t;
173 for (t = tunnels_r[h0^h1]; t; t = t->next) {
174 if (remote == t->parms.iph.daddr) {
175 if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
176 return t;
179 for (t = tunnels_l[h1]; t; t = t->next) {
180 if (local == t->parms.iph.saddr ||
181 (local == t->parms.iph.daddr && MULTICAST(local))) {
182 if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
183 return t;
186 for (t = tunnels_wc[h1]; t; t = t->next) {
187 if (t->parms.i_key == key && (t->dev->flags&IFF_UP))
188 return t;
191 if (ipgre_fb_tunnel_dev->flags&IFF_UP)
192 return netdev_priv(ipgre_fb_tunnel_dev);
193 return NULL;
196 static struct ip_tunnel **ipgre_bucket(struct ip_tunnel *t)
198 u32 remote = t->parms.iph.daddr;
199 u32 local = t->parms.iph.saddr;
200 u32 key = t->parms.i_key;
201 unsigned h = HASH(key);
202 int prio = 0;
204 if (local)
205 prio |= 1;
206 if (remote && !MULTICAST(remote)) {
207 prio |= 2;
208 h ^= HASH(remote);
211 return &tunnels[prio][h];
214 static void ipgre_tunnel_link(struct ip_tunnel *t)
216 struct ip_tunnel **tp = ipgre_bucket(t);
218 t->next = *tp;
219 write_lock_bh(&ipgre_lock);
220 *tp = t;
221 write_unlock_bh(&ipgre_lock);
224 static void ipgre_tunnel_unlink(struct ip_tunnel *t)
226 struct ip_tunnel **tp;
228 for (tp = ipgre_bucket(t); *tp; tp = &(*tp)->next) {
229 if (t == *tp) {
230 write_lock_bh(&ipgre_lock);
231 *tp = t->next;
232 write_unlock_bh(&ipgre_lock);
233 break;
238 static struct ip_tunnel * ipgre_tunnel_locate(struct ip_tunnel_parm *parms, int create)
240 u32 remote = parms->iph.daddr;
241 u32 local = parms->iph.saddr;
242 u32 key = parms->i_key;
243 struct ip_tunnel *t, **tp, *nt;
244 struct net_device *dev;
245 unsigned h = HASH(key);
246 int prio = 0;
247 char name[IFNAMSIZ];
249 if (local)
250 prio |= 1;
251 if (remote && !MULTICAST(remote)) {
252 prio |= 2;
253 h ^= HASH(remote);
255 for (tp = &tunnels[prio][h]; (t = *tp) != NULL; tp = &t->next) {
256 if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) {
257 if (key == t->parms.i_key)
258 return t;
261 if (!create)
262 return NULL;
264 if (parms->name[0])
265 strlcpy(name, parms->name, IFNAMSIZ);
266 else {
267 int i;
268 for (i=1; i<100; i++) {
269 sprintf(name, "gre%d", i);
270 if (__dev_get_by_name(name) == NULL)
271 break;
273 if (i==100)
274 goto failed;
277 dev = alloc_netdev(sizeof(*t), name, ipgre_tunnel_setup);
278 if (!dev)
279 return NULL;
281 dev->init = ipgre_tunnel_init;
282 nt = netdev_priv(dev);
283 nt->parms = *parms;
285 if (register_netdevice(dev) < 0) {
286 free_netdev(dev);
287 goto failed;
290 dev_hold(dev);
291 ipgre_tunnel_link(nt);
292 return nt;
294 failed:
295 return NULL;
298 static void ipgre_tunnel_uninit(struct net_device *dev)
300 ipgre_tunnel_unlink(netdev_priv(dev));
301 dev_put(dev);
305 static void ipgre_err(struct sk_buff *skb, u32 info)
307 #ifndef I_WISH_WORLD_WERE_PERFECT
309 /* It is not :-( All the routers (except for Linux) return only
310 8 bytes of packet payload. It means, that precise relaying of
311 ICMP in the real Internet is absolutely infeasible.
313 Moreover, Cisco "wise men" put GRE key to the third word
314 in GRE header. It makes impossible maintaining even soft state for keyed
315 GRE tunnels with enabled checksum. Tell them "thank you".
317 Well, I wonder, rfc1812 was written by Cisco employee,
318 what the hell these idiots break standrads established
319 by themself???
322 struct iphdr *iph = (struct iphdr*)skb->data;
323 u16 *p = (u16*)(skb->data+(iph->ihl<<2));
324 int grehlen = (iph->ihl<<2) + 4;
325 int type = skb->h.icmph->type;
326 int code = skb->h.icmph->code;
327 struct ip_tunnel *t;
328 u16 flags;
330 flags = p[0];
331 if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
332 if (flags&(GRE_VERSION|GRE_ROUTING))
333 return;
334 if (flags&GRE_KEY) {
335 grehlen += 4;
336 if (flags&GRE_CSUM)
337 grehlen += 4;
341 /* If only 8 bytes returned, keyed message will be dropped here */
342 if (skb_headlen(skb) < grehlen)
343 return;
345 switch (type) {
346 default:
347 case ICMP_PARAMETERPROB:
348 return;
350 case ICMP_DEST_UNREACH:
351 switch (code) {
352 case ICMP_SR_FAILED:
353 case ICMP_PORT_UNREACH:
354 /* Impossible event. */
355 return;
356 case ICMP_FRAG_NEEDED:
357 /* Soft state for pmtu is maintained by IP core. */
358 return;
359 default:
360 /* All others are translated to HOST_UNREACH.
361 rfc2003 contains "deep thoughts" about NET_UNREACH,
362 I believe they are just ether pollution. --ANK
364 break;
366 break;
367 case ICMP_TIME_EXCEEDED:
368 if (code != ICMP_EXC_TTL)
369 return;
370 break;
373 read_lock(&ipgre_lock);
374 t = ipgre_tunnel_lookup(iph->daddr, iph->saddr, (flags&GRE_KEY) ? *(((u32*)p) + (grehlen>>2) - 1) : 0);
375 if (t == NULL || t->parms.iph.daddr == 0 || MULTICAST(t->parms.iph.daddr))
376 goto out;
378 if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
379 goto out;
381 if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO)
382 t->err_count++;
383 else
384 t->err_count = 1;
385 t->err_time = jiffies;
386 out:
387 read_unlock(&ipgre_lock);
388 return;
389 #else
390 struct iphdr *iph = (struct iphdr*)dp;
391 struct iphdr *eiph;
392 u16 *p = (u16*)(dp+(iph->ihl<<2));
393 int type = skb->h.icmph->type;
394 int code = skb->h.icmph->code;
395 int rel_type = 0;
396 int rel_code = 0;
397 int rel_info = 0;
398 u16 flags;
399 int grehlen = (iph->ihl<<2) + 4;
400 struct sk_buff *skb2;
401 struct flowi fl;
402 struct rtable *rt;
404 if (p[1] != htons(ETH_P_IP))
405 return;
407 flags = p[0];
408 if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
409 if (flags&(GRE_VERSION|GRE_ROUTING))
410 return;
411 if (flags&GRE_CSUM)
412 grehlen += 4;
413 if (flags&GRE_KEY)
414 grehlen += 4;
415 if (flags&GRE_SEQ)
416 grehlen += 4;
418 if (len < grehlen + sizeof(struct iphdr))
419 return;
420 eiph = (struct iphdr*)(dp + grehlen);
422 switch (type) {
423 default:
424 return;
425 case ICMP_PARAMETERPROB:
426 if (skb->h.icmph->un.gateway < (iph->ihl<<2))
427 return;
429 /* So... This guy found something strange INSIDE encapsulated
430 packet. Well, he is fool, but what can we do ?
432 rel_type = ICMP_PARAMETERPROB;
433 rel_info = skb->h.icmph->un.gateway - grehlen;
434 break;
436 case ICMP_DEST_UNREACH:
437 switch (code) {
438 case ICMP_SR_FAILED:
439 case ICMP_PORT_UNREACH:
440 /* Impossible event. */
441 return;
442 case ICMP_FRAG_NEEDED:
443 /* And it is the only really necessary thing :-) */
444 rel_info = ntohs(skb->h.icmph->un.frag.mtu);
445 if (rel_info < grehlen+68)
446 return;
447 rel_info -= grehlen;
448 /* BSD 4.2 MORE DOES NOT EXIST IN NATURE. */
449 if (rel_info > ntohs(eiph->tot_len))
450 return;
451 break;
452 default:
453 /* All others are translated to HOST_UNREACH.
454 rfc2003 contains "deep thoughts" about NET_UNREACH,
455 I believe, it is just ether pollution. --ANK
457 rel_type = ICMP_DEST_UNREACH;
458 rel_code = ICMP_HOST_UNREACH;
459 break;
461 break;
462 case ICMP_TIME_EXCEEDED:
463 if (code != ICMP_EXC_TTL)
464 return;
465 break;
468 /* Prepare fake skb to feed it to icmp_send */
469 skb2 = skb_clone(skb, GFP_ATOMIC);
470 if (skb2 == NULL)
471 return;
472 dst_release(skb2->dst);
473 skb2->dst = NULL;
474 skb_pull(skb2, skb->data - (u8*)eiph);
475 skb2->nh.raw = skb2->data;
477 /* Try to guess incoming interface */
478 memset(&fl, 0, sizeof(fl));
479 fl.fl4_dst = eiph->saddr;
480 fl.fl4_tos = RT_TOS(eiph->tos);
481 fl.proto = IPPROTO_GRE;
482 if (ip_route_output_key(&rt, &fl)) {
483 kfree_skb(skb2);
484 return;
486 skb2->dev = rt->u.dst.dev;
488 /* route "incoming" packet */
489 if (rt->rt_flags&RTCF_LOCAL) {
490 ip_rt_put(rt);
491 rt = NULL;
492 fl.fl4_dst = eiph->daddr;
493 fl.fl4_src = eiph->saddr;
494 fl.fl4_tos = eiph->tos;
495 if (ip_route_output_key(&rt, &fl) ||
496 rt->u.dst.dev->type != ARPHRD_IPGRE) {
497 ip_rt_put(rt);
498 kfree_skb(skb2);
499 return;
501 } else {
502 ip_rt_put(rt);
503 if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos, skb2->dev) ||
504 skb2->dst->dev->type != ARPHRD_IPGRE) {
505 kfree_skb(skb2);
506 return;
510 /* change mtu on this route */
511 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
512 if (rel_info > dst_mtu(skb2->dst)) {
513 kfree_skb(skb2);
514 return;
516 skb2->dst->ops->update_pmtu(skb2->dst, rel_info);
517 rel_info = htonl(rel_info);
518 } else if (type == ICMP_TIME_EXCEEDED) {
519 struct ip_tunnel *t = netdev_priv(skb2->dev);
520 if (t->parms.iph.ttl) {
521 rel_type = ICMP_DEST_UNREACH;
522 rel_code = ICMP_HOST_UNREACH;
526 icmp_send(skb2, rel_type, rel_code, rel_info);
527 kfree_skb(skb2);
528 #endif
531 static inline void ipgre_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
533 if (INET_ECN_is_ce(iph->tos)) {
534 if (skb->protocol == htons(ETH_P_IP)) {
535 IP_ECN_set_ce(skb->nh.iph);
536 } else if (skb->protocol == htons(ETH_P_IPV6)) {
537 IP6_ECN_set_ce(skb->nh.ipv6h);
542 static inline u8
543 ipgre_ecn_encapsulate(u8 tos, struct iphdr *old_iph, struct sk_buff *skb)
545 u8 inner = 0;
546 if (skb->protocol == htons(ETH_P_IP))
547 inner = old_iph->tos;
548 else if (skb->protocol == htons(ETH_P_IPV6))
549 inner = ipv6_get_dsfield((struct ipv6hdr *)old_iph);
550 return INET_ECN_encapsulate(tos, inner);
553 static int ipgre_rcv(struct sk_buff *skb)
555 struct iphdr *iph;
556 u8 *h;
557 u16 flags;
558 u16 csum = 0;
559 u32 key = 0;
560 u32 seqno = 0;
561 struct ip_tunnel *tunnel;
562 int offset = 4;
564 if (!pskb_may_pull(skb, 16))
565 goto drop_nolock;
567 iph = skb->nh.iph;
568 h = skb->data;
569 flags = *(u16*)h;
571 if (flags&(GRE_CSUM|GRE_KEY|GRE_ROUTING|GRE_SEQ|GRE_VERSION)) {
572 /* - Version must be 0.
573 - We do not support routing headers.
575 if (flags&(GRE_VERSION|GRE_ROUTING))
576 goto drop_nolock;
578 if (flags&GRE_CSUM) {
579 switch (skb->ip_summed) {
580 case CHECKSUM_HW:
581 csum = (u16)csum_fold(skb->csum);
582 if (!csum)
583 break;
584 /* fall through */
585 case CHECKSUM_NONE:
586 skb->csum = 0;
587 csum = __skb_checksum_complete(skb);
588 skb->ip_summed = CHECKSUM_HW;
590 offset += 4;
592 if (flags&GRE_KEY) {
593 key = *(u32*)(h + offset);
594 offset += 4;
596 if (flags&GRE_SEQ) {
597 seqno = ntohl(*(u32*)(h + offset));
598 offset += 4;
602 read_lock(&ipgre_lock);
603 if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) {
604 secpath_reset(skb);
606 skb->protocol = *(u16*)(h + 2);
607 /* WCCP version 1 and 2 protocol decoding.
608 * - Change protocol to IP
609 * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
611 if (flags == 0 &&
612 skb->protocol == __constant_htons(ETH_P_WCCP)) {
613 skb->protocol = __constant_htons(ETH_P_IP);
614 if ((*(h + offset) & 0xF0) != 0x40)
615 offset += 4;
618 skb->mac.raw = skb->nh.raw;
619 skb->nh.raw = __pskb_pull(skb, offset);
620 skb_postpull_rcsum(skb, skb->h.raw, offset);
621 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
622 skb->pkt_type = PACKET_HOST;
623 #ifdef CONFIG_NET_IPGRE_BROADCAST
624 if (MULTICAST(iph->daddr)) {
625 /* Looped back packet, drop it! */
626 if (((struct rtable*)skb->dst)->fl.iif == 0)
627 goto drop;
628 tunnel->stat.multicast++;
629 skb->pkt_type = PACKET_BROADCAST;
631 #endif
633 if (((flags&GRE_CSUM) && csum) ||
634 (!(flags&GRE_CSUM) && tunnel->parms.i_flags&GRE_CSUM)) {
635 tunnel->stat.rx_crc_errors++;
636 tunnel->stat.rx_errors++;
637 goto drop;
639 if (tunnel->parms.i_flags&GRE_SEQ) {
640 if (!(flags&GRE_SEQ) ||
641 (tunnel->i_seqno && (s32)(seqno - tunnel->i_seqno) < 0)) {
642 tunnel->stat.rx_fifo_errors++;
643 tunnel->stat.rx_errors++;
644 goto drop;
646 tunnel->i_seqno = seqno + 1;
648 tunnel->stat.rx_packets++;
649 tunnel->stat.rx_bytes += skb->len;
650 skb->dev = tunnel->dev;
651 dst_release(skb->dst);
652 skb->dst = NULL;
653 nf_reset(skb);
654 ipgre_ecn_decapsulate(iph, skb);
655 netif_rx(skb);
656 read_unlock(&ipgre_lock);
657 return(0);
659 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
661 drop:
662 read_unlock(&ipgre_lock);
663 drop_nolock:
664 kfree_skb(skb);
665 return(0);
668 static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
670 struct ip_tunnel *tunnel = netdev_priv(dev);
671 struct net_device_stats *stats = &tunnel->stat;
672 struct iphdr *old_iph = skb->nh.iph;
673 struct iphdr *tiph;
674 u8 tos;
675 u16 df;
676 struct rtable *rt; /* Route to the other host */
677 struct net_device *tdev; /* Device to other host */
678 struct iphdr *iph; /* Our new IP header */
679 int max_headroom; /* The extra header space needed */
680 int gre_hlen;
681 u32 dst;
682 int mtu;
684 if (tunnel->recursion++) {
685 tunnel->stat.collisions++;
686 goto tx_error;
689 if (dev->hard_header) {
690 gre_hlen = 0;
691 tiph = (struct iphdr*)skb->data;
692 } else {
693 gre_hlen = tunnel->hlen;
694 tiph = &tunnel->parms.iph;
697 if ((dst = tiph->daddr) == 0) {
698 /* NBMA tunnel */
700 if (skb->dst == NULL) {
701 tunnel->stat.tx_fifo_errors++;
702 goto tx_error;
705 if (skb->protocol == htons(ETH_P_IP)) {
706 rt = (struct rtable*)skb->dst;
707 if ((dst = rt->rt_gateway) == 0)
708 goto tx_error_icmp;
710 #ifdef CONFIG_IPV6
711 else if (skb->protocol == htons(ETH_P_IPV6)) {
712 struct in6_addr *addr6;
713 int addr_type;
714 struct neighbour *neigh = skb->dst->neighbour;
716 if (neigh == NULL)
717 goto tx_error;
719 addr6 = (struct in6_addr*)&neigh->primary_key;
720 addr_type = ipv6_addr_type(addr6);
722 if (addr_type == IPV6_ADDR_ANY) {
723 addr6 = &skb->nh.ipv6h->daddr;
724 addr_type = ipv6_addr_type(addr6);
727 if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
728 goto tx_error_icmp;
730 dst = addr6->s6_addr32[3];
732 #endif
733 else
734 goto tx_error;
737 tos = tiph->tos;
738 if (tos&1) {
739 if (skb->protocol == htons(ETH_P_IP))
740 tos = old_iph->tos;
741 tos &= ~1;
745 struct flowi fl = { .oif = tunnel->parms.link,
746 .nl_u = { .ip4_u =
747 { .daddr = dst,
748 .saddr = tiph->saddr,
749 .tos = RT_TOS(tos) } },
750 .proto = IPPROTO_GRE };
751 if (ip_route_output_key(&rt, &fl)) {
752 tunnel->stat.tx_carrier_errors++;
753 goto tx_error;
756 tdev = rt->u.dst.dev;
758 if (tdev == dev) {
759 ip_rt_put(rt);
760 tunnel->stat.collisions++;
761 goto tx_error;
764 df = tiph->frag_off;
765 if (df)
766 mtu = dst_mtu(&rt->u.dst) - tunnel->hlen;
767 else
768 mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
770 if (skb->dst)
771 skb->dst->ops->update_pmtu(skb->dst, mtu);
773 if (skb->protocol == htons(ETH_P_IP)) {
774 df |= (old_iph->frag_off&htons(IP_DF));
776 if ((old_iph->frag_off&htons(IP_DF)) &&
777 mtu < ntohs(old_iph->tot_len)) {
778 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
779 ip_rt_put(rt);
780 goto tx_error;
783 #ifdef CONFIG_IPV6
784 else if (skb->protocol == htons(ETH_P_IPV6)) {
785 struct rt6_info *rt6 = (struct rt6_info*)skb->dst;
787 if (rt6 && mtu < dst_mtu(skb->dst) && mtu >= IPV6_MIN_MTU) {
788 if ((tunnel->parms.iph.daddr && !MULTICAST(tunnel->parms.iph.daddr)) ||
789 rt6->rt6i_dst.plen == 128) {
790 rt6->rt6i_flags |= RTF_MODIFIED;
791 skb->dst->metrics[RTAX_MTU-1] = mtu;
795 if (mtu >= IPV6_MIN_MTU && mtu < skb->len - tunnel->hlen + gre_hlen) {
796 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
797 ip_rt_put(rt);
798 goto tx_error;
801 #endif
803 if (tunnel->err_count > 0) {
804 if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) {
805 tunnel->err_count--;
807 dst_link_failure(skb);
808 } else
809 tunnel->err_count = 0;
812 max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen;
814 if (skb_headroom(skb) < max_headroom || skb_cloned(skb) || skb_shared(skb)) {
815 struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
816 if (!new_skb) {
817 ip_rt_put(rt);
818 stats->tx_dropped++;
819 dev_kfree_skb(skb);
820 tunnel->recursion--;
821 return 0;
823 if (skb->sk)
824 skb_set_owner_w(new_skb, skb->sk);
825 dev_kfree_skb(skb);
826 skb = new_skb;
827 old_iph = skb->nh.iph;
830 skb->h.raw = skb->nh.raw;
831 skb->nh.raw = skb_push(skb, gre_hlen);
832 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
833 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE|IPSKB_XFRM_TRANSFORMED);
834 dst_release(skb->dst);
835 skb->dst = &rt->u.dst;
838 * Push down and install the IPIP header.
841 iph = skb->nh.iph;
842 iph->version = 4;
843 iph->ihl = sizeof(struct iphdr) >> 2;
844 iph->frag_off = df;
845 iph->protocol = IPPROTO_GRE;
846 iph->tos = ipgre_ecn_encapsulate(tos, old_iph, skb);
847 iph->daddr = rt->rt_dst;
848 iph->saddr = rt->rt_src;
850 if ((iph->ttl = tiph->ttl) == 0) {
851 if (skb->protocol == htons(ETH_P_IP))
852 iph->ttl = old_iph->ttl;
853 #ifdef CONFIG_IPV6
854 else if (skb->protocol == htons(ETH_P_IPV6))
855 iph->ttl = ((struct ipv6hdr*)old_iph)->hop_limit;
856 #endif
857 else
858 iph->ttl = dst_metric(&rt->u.dst, RTAX_HOPLIMIT);
861 ((u16*)(iph+1))[0] = tunnel->parms.o_flags;
862 ((u16*)(iph+1))[1] = skb->protocol;
864 if (tunnel->parms.o_flags&(GRE_KEY|GRE_CSUM|GRE_SEQ)) {
865 u32 *ptr = (u32*)(((u8*)iph) + tunnel->hlen - 4);
867 if (tunnel->parms.o_flags&GRE_SEQ) {
868 ++tunnel->o_seqno;
869 *ptr = htonl(tunnel->o_seqno);
870 ptr--;
872 if (tunnel->parms.o_flags&GRE_KEY) {
873 *ptr = tunnel->parms.o_key;
874 ptr--;
876 if (tunnel->parms.o_flags&GRE_CSUM) {
877 *ptr = 0;
878 *(__u16*)ptr = ip_compute_csum((void*)(iph+1), skb->len - sizeof(struct iphdr));
882 nf_reset(skb);
884 IPTUNNEL_XMIT();
885 tunnel->recursion--;
886 return 0;
888 tx_error_icmp:
889 dst_link_failure(skb);
891 tx_error:
892 stats->tx_errors++;
893 dev_kfree_skb(skb);
894 tunnel->recursion--;
895 return 0;
898 static int
899 ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
901 int err = 0;
902 struct ip_tunnel_parm p;
903 struct ip_tunnel *t;
905 switch (cmd) {
906 case SIOCGETTUNNEL:
907 t = NULL;
908 if (dev == ipgre_fb_tunnel_dev) {
909 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) {
910 err = -EFAULT;
911 break;
913 t = ipgre_tunnel_locate(&p, 0);
915 if (t == NULL)
916 t = netdev_priv(dev);
917 memcpy(&p, &t->parms, sizeof(p));
918 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
919 err = -EFAULT;
920 break;
922 case SIOCADDTUNNEL:
923 case SIOCCHGTUNNEL:
924 err = -EPERM;
925 if (!capable(CAP_NET_ADMIN))
926 goto done;
928 err = -EFAULT;
929 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
930 goto done;
932 err = -EINVAL;
933 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_GRE ||
934 p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)) ||
935 ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING)))
936 goto done;
937 if (p.iph.ttl)
938 p.iph.frag_off |= htons(IP_DF);
940 if (!(p.i_flags&GRE_KEY))
941 p.i_key = 0;
942 if (!(p.o_flags&GRE_KEY))
943 p.o_key = 0;
945 t = ipgre_tunnel_locate(&p, cmd == SIOCADDTUNNEL);
947 if (dev != ipgre_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) {
948 if (t != NULL) {
949 if (t->dev != dev) {
950 err = -EEXIST;
951 break;
953 } else {
954 unsigned nflags=0;
956 t = netdev_priv(dev);
958 if (MULTICAST(p.iph.daddr))
959 nflags = IFF_BROADCAST;
960 else if (p.iph.daddr)
961 nflags = IFF_POINTOPOINT;
963 if ((dev->flags^nflags)&(IFF_POINTOPOINT|IFF_BROADCAST)) {
964 err = -EINVAL;
965 break;
967 ipgre_tunnel_unlink(t);
968 t->parms.iph.saddr = p.iph.saddr;
969 t->parms.iph.daddr = p.iph.daddr;
970 t->parms.i_key = p.i_key;
971 t->parms.o_key = p.o_key;
972 memcpy(dev->dev_addr, &p.iph.saddr, 4);
973 memcpy(dev->broadcast, &p.iph.daddr, 4);
974 ipgre_tunnel_link(t);
975 netdev_state_change(dev);
979 if (t) {
980 err = 0;
981 if (cmd == SIOCCHGTUNNEL) {
982 t->parms.iph.ttl = p.iph.ttl;
983 t->parms.iph.tos = p.iph.tos;
984 t->parms.iph.frag_off = p.iph.frag_off;
986 if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p)))
987 err = -EFAULT;
988 } else
989 err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
990 break;
992 case SIOCDELTUNNEL:
993 err = -EPERM;
994 if (!capable(CAP_NET_ADMIN))
995 goto done;
997 if (dev == ipgre_fb_tunnel_dev) {
998 err = -EFAULT;
999 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
1000 goto done;
1001 err = -ENOENT;
1002 if ((t = ipgre_tunnel_locate(&p, 0)) == NULL)
1003 goto done;
1004 err = -EPERM;
1005 if (t == netdev_priv(ipgre_fb_tunnel_dev))
1006 goto done;
1007 dev = t->dev;
1009 err = unregister_netdevice(dev);
1010 break;
1012 default:
1013 err = -EINVAL;
1016 done:
1017 return err;
1020 static struct net_device_stats *ipgre_tunnel_get_stats(struct net_device *dev)
1022 return &(((struct ip_tunnel*)netdev_priv(dev))->stat);
1025 static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
1027 struct ip_tunnel *tunnel = netdev_priv(dev);
1028 if (new_mtu < 68 || new_mtu > 0xFFF8 - tunnel->hlen)
1029 return -EINVAL;
1030 dev->mtu = new_mtu;
1031 return 0;
1034 #ifdef CONFIG_NET_IPGRE_BROADCAST
1035 /* Nice toy. Unfortunately, useless in real life :-)
1036 It allows to construct virtual multiprotocol broadcast "LAN"
1037 over the Internet, provided multicast routing is tuned.
1040 I have no idea was this bicycle invented before me,
1041 so that I had to set ARPHRD_IPGRE to a random value.
1042 I have an impression, that Cisco could make something similar,
1043 but this feature is apparently missing in IOS<=11.2(8).
1045 I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks
1046 with broadcast 224.66.66.66. If you have access to mbone, play with me :-)
1048 ping -t 255 224.66.66.66
1050 If nobody answers, mbone does not work.
1052 ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255
1053 ip addr add 10.66.66.<somewhat>/24 dev Universe
1054 ifconfig Universe up
1055 ifconfig Universe add fe80::<Your_real_addr>/10
1056 ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96
1057 ftp 10.66.66.66
1059 ftp fec0:6666:6666::193.233.7.65
1064 static int ipgre_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
1065 void *daddr, void *saddr, unsigned len)
1067 struct ip_tunnel *t = netdev_priv(dev);
1068 struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen);
1069 u16 *p = (u16*)(iph+1);
1071 memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
1072 p[0] = t->parms.o_flags;
1073 p[1] = htons(type);
1076 * Set the source hardware address.
1079 if (saddr)
1080 memcpy(&iph->saddr, saddr, 4);
1082 if (daddr) {
1083 memcpy(&iph->daddr, daddr, 4);
1084 return t->hlen;
1086 if (iph->daddr && !MULTICAST(iph->daddr))
1087 return t->hlen;
1089 return -t->hlen;
1092 static int ipgre_open(struct net_device *dev)
1094 struct ip_tunnel *t = netdev_priv(dev);
1096 if (MULTICAST(t->parms.iph.daddr)) {
1097 struct flowi fl = { .oif = t->parms.link,
1098 .nl_u = { .ip4_u =
1099 { .daddr = t->parms.iph.daddr,
1100 .saddr = t->parms.iph.saddr,
1101 .tos = RT_TOS(t->parms.iph.tos) } },
1102 .proto = IPPROTO_GRE };
1103 struct rtable *rt;
1104 if (ip_route_output_key(&rt, &fl))
1105 return -EADDRNOTAVAIL;
1106 dev = rt->u.dst.dev;
1107 ip_rt_put(rt);
1108 if (__in_dev_get_rtnl(dev) == NULL)
1109 return -EADDRNOTAVAIL;
1110 t->mlink = dev->ifindex;
1111 ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);
1113 return 0;
1116 static int ipgre_close(struct net_device *dev)
1118 struct ip_tunnel *t = netdev_priv(dev);
1119 if (MULTICAST(t->parms.iph.daddr) && t->mlink) {
1120 struct in_device *in_dev = inetdev_by_index(t->mlink);
1121 if (in_dev) {
1122 ip_mc_dec_group(in_dev, t->parms.iph.daddr);
1123 in_dev_put(in_dev);
1126 return 0;
1129 #endif
1131 static void ipgre_tunnel_setup(struct net_device *dev)
1133 SET_MODULE_OWNER(dev);
1134 dev->uninit = ipgre_tunnel_uninit;
1135 dev->destructor = free_netdev;
1136 dev->hard_start_xmit = ipgre_tunnel_xmit;
1137 dev->get_stats = ipgre_tunnel_get_stats;
1138 dev->do_ioctl = ipgre_tunnel_ioctl;
1139 dev->change_mtu = ipgre_tunnel_change_mtu;
1141 dev->type = ARPHRD_IPGRE;
1142 dev->hard_header_len = LL_MAX_HEADER + sizeof(struct iphdr) + 4;
1143 dev->mtu = ETH_DATA_LEN - sizeof(struct iphdr) - 4;
1144 dev->flags = IFF_NOARP;
1145 dev->iflink = 0;
1146 dev->addr_len = 4;
1149 static int ipgre_tunnel_init(struct net_device *dev)
1151 struct net_device *tdev = NULL;
1152 struct ip_tunnel *tunnel;
1153 struct iphdr *iph;
1154 int hlen = LL_MAX_HEADER;
1155 int mtu = ETH_DATA_LEN;
1156 int addend = sizeof(struct iphdr) + 4;
1158 tunnel = netdev_priv(dev);
1159 iph = &tunnel->parms.iph;
1161 tunnel->dev = dev;
1162 strcpy(tunnel->parms.name, dev->name);
1164 memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
1165 memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
1167 /* Guess output device to choose reasonable mtu and hard_header_len */
1169 if (iph->daddr) {
1170 struct flowi fl = { .oif = tunnel->parms.link,
1171 .nl_u = { .ip4_u =
1172 { .daddr = iph->daddr,
1173 .saddr = iph->saddr,
1174 .tos = RT_TOS(iph->tos) } },
1175 .proto = IPPROTO_GRE };
1176 struct rtable *rt;
1177 if (!ip_route_output_key(&rt, &fl)) {
1178 tdev = rt->u.dst.dev;
1179 ip_rt_put(rt);
1182 dev->flags |= IFF_POINTOPOINT;
1184 #ifdef CONFIG_NET_IPGRE_BROADCAST
1185 if (MULTICAST(iph->daddr)) {
1186 if (!iph->saddr)
1187 return -EINVAL;
1188 dev->flags = IFF_BROADCAST;
1189 dev->hard_header = ipgre_header;
1190 dev->open = ipgre_open;
1191 dev->stop = ipgre_close;
1193 #endif
1196 if (!tdev && tunnel->parms.link)
1197 tdev = __dev_get_by_index(tunnel->parms.link);
1199 if (tdev) {
1200 hlen = tdev->hard_header_len;
1201 mtu = tdev->mtu;
1203 dev->iflink = tunnel->parms.link;
1205 /* Precalculate GRE options length */
1206 if (tunnel->parms.o_flags&(GRE_CSUM|GRE_KEY|GRE_SEQ)) {
1207 if (tunnel->parms.o_flags&GRE_CSUM)
1208 addend += 4;
1209 if (tunnel->parms.o_flags&GRE_KEY)
1210 addend += 4;
1211 if (tunnel->parms.o_flags&GRE_SEQ)
1212 addend += 4;
1214 dev->hard_header_len = hlen + addend;
1215 dev->mtu = mtu - addend;
1216 tunnel->hlen = addend;
1217 return 0;
1220 static int __init ipgre_fb_tunnel_init(struct net_device *dev)
1222 struct ip_tunnel *tunnel = netdev_priv(dev);
1223 struct iphdr *iph = &tunnel->parms.iph;
1225 tunnel->dev = dev;
1226 strcpy(tunnel->parms.name, dev->name);
1228 iph->version = 4;
1229 iph->protocol = IPPROTO_GRE;
1230 iph->ihl = 5;
1231 tunnel->hlen = sizeof(struct iphdr) + 4;
1233 dev_hold(dev);
1234 tunnels_wc[0] = tunnel;
1235 return 0;
1239 static struct net_protocol ipgre_protocol = {
1240 .handler = ipgre_rcv,
1241 .err_handler = ipgre_err,
1246 * And now the modules code and kernel interface.
1249 static int __init ipgre_init(void)
1251 int err;
1253 printk(KERN_INFO "GRE over IPv4 tunneling driver\n");
1255 if (inet_add_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) {
1256 printk(KERN_INFO "ipgre init: can't add protocol\n");
1257 return -EAGAIN;
1260 ipgre_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0",
1261 ipgre_tunnel_setup);
1262 if (!ipgre_fb_tunnel_dev) {
1263 err = -ENOMEM;
1264 goto err1;
1267 ipgre_fb_tunnel_dev->init = ipgre_fb_tunnel_init;
1269 if ((err = register_netdev(ipgre_fb_tunnel_dev)))
1270 goto err2;
1271 out:
1272 return err;
1273 err2:
1274 free_netdev(ipgre_fb_tunnel_dev);
1275 err1:
1276 inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
1277 goto out;
1280 static void __exit ipgre_destroy_tunnels(void)
1282 int prio;
1284 for (prio = 0; prio < 4; prio++) {
1285 int h;
1286 for (h = 0; h < HASH_SIZE; h++) {
1287 struct ip_tunnel *t;
1288 while ((t = tunnels[prio][h]) != NULL)
1289 unregister_netdevice(t->dev);
1294 static void __exit ipgre_fini(void)
1296 if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0)
1297 printk(KERN_INFO "ipgre close: can't remove protocol\n");
1299 rtnl_lock();
1300 ipgre_destroy_tunnels();
1301 rtnl_unlock();
1304 module_init(ipgre_init);
1305 module_exit(ipgre_fini);
1306 MODULE_LICENSE("GPL");