xref: /freebsd/sys/net/if_gre.c (revision 98e0ffaefb0f241cda3a72395d3be04192ae0d47)
1 /*-
2  * Copyright (c) 1998 The NetBSD Foundation, Inc.
3  * Copyright (c) 2014 Andrey V. Elsukov <ae@FreeBSD.org>
4  * All rights reserved.
5  *
6  * This code is derived from software contributed to The NetBSD Foundation
7  * by Heiko W.Rupp <hwr@pilhuhn.de>
8  *
9  * IPv6-over-GRE contributed by Gert Doering <gert@greenie.muc.de>
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30  * POSSIBILITY OF SUCH DAMAGE.
31  *
32  * $NetBSD: if_gre.c,v 1.49 2003/12/11 00:22:29 itojun Exp $
33  */
34 
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37 
38 #include "opt_inet.h"
39 #include "opt_inet6.h"
40 
41 #include <sys/param.h>
42 #include <sys/jail.h>
43 #include <sys/kernel.h>
44 #include <sys/lock.h>
45 #include <sys/libkern.h>
46 #include <sys/malloc.h>
47 #include <sys/module.h>
48 #include <sys/mbuf.h>
49 #include <sys/priv.h>
50 #include <sys/proc.h>
51 #include <sys/protosw.h>
52 #include <sys/rmlock.h>
53 #include <sys/socket.h>
54 #include <sys/sockio.h>
55 #include <sys/sx.h>
56 #include <sys/sysctl.h>
57 #include <sys/syslog.h>
58 #include <sys/systm.h>
59 
60 #include <net/ethernet.h>
61 #include <net/if.h>
62 #include <net/if_var.h>
63 #include <net/if_clone.h>
64 #include <net/if_types.h>
65 #include <net/netisr.h>
66 #include <net/vnet.h>
67 #include <net/route.h>
68 
69 #include <netinet/in.h>
70 #ifdef INET
71 #include <netinet/in_systm.h>
72 #include <netinet/in_var.h>
73 #include <netinet/ip.h>
74 #include <netinet/ip_var.h>
75 #endif
76 
77 #ifdef INET6
78 #include <netinet/ip6.h>
79 #include <netinet6/in6_var.h>
80 #include <netinet6/ip6_var.h>
81 #include <netinet6/scope6_var.h>
82 #endif
83 
84 #include <netinet/ip_encap.h>
85 #include <net/bpf.h>
86 #include <net/if_gre.h>
87 
88 #include <machine/in_cksum.h>
89 #include <security/mac/mac_framework.h>
90 
91 #define	GREMTU			1500
92 static const char grename[] = "gre";
93 static MALLOC_DEFINE(M_GRE, grename, "Generic Routing Encapsulation");
94 static VNET_DEFINE(struct mtx, gre_mtx);
95 #define	V_gre_mtx	VNET(gre_mtx)
96 #define	GRE_LIST_LOCK_INIT(x)		mtx_init(&V_gre_mtx, "gre_mtx", NULL, \
97 					    MTX_DEF)
98 #define	GRE_LIST_LOCK_DESTROY(x)	mtx_destroy(&V_gre_mtx)
99 #define	GRE_LIST_LOCK(x)		mtx_lock(&V_gre_mtx)
100 #define	GRE_LIST_UNLOCK(x)		mtx_unlock(&V_gre_mtx)
101 
102 static VNET_DEFINE(LIST_HEAD(, gre_softc), gre_softc_list);
103 #define	V_gre_softc_list	VNET(gre_softc_list)
104 static struct sx gre_ioctl_sx;
105 SX_SYSINIT(gre_ioctl_sx, &gre_ioctl_sx, "gre_ioctl");
106 
107 static int	gre_clone_create(struct if_clone *, int, caddr_t);
108 static void	gre_clone_destroy(struct ifnet *);
109 static VNET_DEFINE(struct if_clone *, gre_cloner);
110 #define	V_gre_cloner	VNET(gre_cloner)
111 
112 static void	gre_qflush(struct ifnet *);
113 static int	gre_transmit(struct ifnet *, struct mbuf *);
114 static int	gre_ioctl(struct ifnet *, u_long, caddr_t);
115 static int	gre_output(struct ifnet *, struct mbuf *,
116 		    const struct sockaddr *, struct route *);
117 
118 static void	gre_updatehdr(struct gre_softc *);
119 static int	gre_set_tunnel(struct ifnet *, struct sockaddr *,
120     struct sockaddr *);
121 static void	gre_delete_tunnel(struct ifnet *);
122 
123 SYSCTL_DECL(_net_link);
124 static SYSCTL_NODE(_net_link, IFT_TUNNEL, gre, CTLFLAG_RW, 0,
125     "Generic Routing Encapsulation");
126 #ifndef MAX_GRE_NEST
127 /*
128  * This macro controls the default upper limitation on nesting of gre tunnels.
129  * Since, setting a large value to this macro with a careless configuration
130  * may introduce system crash, we don't allow any nestings by default.
131  * If you need to configure nested gre tunnels, you can define this macro
132  * in your kernel configuration file.  However, if you do so, please be
133  * careful to configure the tunnels so that it won't make a loop.
134  */
135 #define MAX_GRE_NEST 1
136 #endif
137 
138 static VNET_DEFINE(int, max_gre_nesting) = MAX_GRE_NEST;
139 #define	V_max_gre_nesting	VNET(max_gre_nesting)
140 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW | CTLFLAG_VNET,
141     &VNET_NAME(max_gre_nesting), 0, "Max nested tunnels");
142 
143 static void
144 vnet_gre_init(const void *unused __unused)
145 {
146 	LIST_INIT(&V_gre_softc_list);
147 	GRE_LIST_LOCK_INIT();
148 	V_gre_cloner = if_clone_simple(grename, gre_clone_create,
149 	    gre_clone_destroy, 0);
150 }
151 VNET_SYSINIT(vnet_gre_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
152     vnet_gre_init, NULL);
153 
154 static void
155 vnet_gre_uninit(const void *unused __unused)
156 {
157 
158 	if_clone_detach(V_gre_cloner);
159 	GRE_LIST_LOCK_DESTROY();
160 }
161 VNET_SYSUNINIT(vnet_gre_uninit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
162     vnet_gre_uninit, NULL);
163 
164 static int
165 gre_clone_create(struct if_clone *ifc, int unit, caddr_t params)
166 {
167 	struct gre_softc *sc;
168 
169 	sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK | M_ZERO);
170 	sc->gre_fibnum = curthread->td_proc->p_fibnum;
171 	GRE2IFP(sc) = if_alloc(IFT_TUNNEL);
172 	GRE_LOCK_INIT(sc);
173 	GRE2IFP(sc)->if_softc = sc;
174 	if_initname(GRE2IFP(sc), grename, unit);
175 
176 	GRE2IFP(sc)->if_mtu = sc->gre_mtu = GREMTU;
177 	GRE2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
178 	GRE2IFP(sc)->if_output = gre_output;
179 	GRE2IFP(sc)->if_ioctl = gre_ioctl;
180 	GRE2IFP(sc)->if_transmit = gre_transmit;
181 	GRE2IFP(sc)->if_qflush = gre_qflush;
182 	if_attach(GRE2IFP(sc));
183 	bpfattach(GRE2IFP(sc), DLT_NULL, sizeof(u_int32_t));
184 	GRE_LIST_LOCK();
185 	LIST_INSERT_HEAD(&V_gre_softc_list, sc, gre_list);
186 	GRE_LIST_UNLOCK();
187 	return (0);
188 }
189 
190 static void
191 gre_clone_destroy(struct ifnet *ifp)
192 {
193 	struct gre_softc *sc;
194 
195 	sx_xlock(&gre_ioctl_sx);
196 	sc = ifp->if_softc;
197 	gre_delete_tunnel(ifp);
198 	GRE_LIST_LOCK();
199 	LIST_REMOVE(sc, gre_list);
200 	GRE_LIST_UNLOCK();
201 	bpfdetach(ifp);
202 	if_detach(ifp);
203 	ifp->if_softc = NULL;
204 	sx_xunlock(&gre_ioctl_sx);
205 
206 	if_free(ifp);
207 	GRE_LOCK_DESTROY(sc);
208 	free(sc, M_GRE);
209 }
210 
211 static int
212 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
213 {
214 	GRE_RLOCK_TRACKER;
215 	struct ifreq *ifr = (struct ifreq *)data;
216 	struct sockaddr *src, *dst;
217 	struct gre_softc *sc;
218 #ifdef INET
219 	struct sockaddr_in *sin = NULL;
220 #endif
221 #ifdef INET6
222 	struct sockaddr_in6 *sin6 = NULL;
223 #endif
224 	uint32_t opt;
225 	int error;
226 
227 	switch (cmd) {
228 	case SIOCSIFMTU:
229 		 /* XXX: */
230 		if (ifr->ifr_mtu < 576)
231 			return (EINVAL);
232 		break;
233 	case SIOCSIFADDR:
234 		ifp->if_flags |= IFF_UP;
235 	case SIOCSIFFLAGS:
236 	case SIOCADDMULTI:
237 	case SIOCDELMULTI:
238 		return (0);
239 	case GRESADDRS:
240 	case GRESADDRD:
241 	case GREGADDRS:
242 	case GREGADDRD:
243 	case GRESPROTO:
244 	case GREGPROTO:
245 		return (EOPNOTSUPP);
246 	}
247 	src = dst = NULL;
248 	sx_xlock(&gre_ioctl_sx);
249 	sc = ifp->if_softc;
250 	if (sc == NULL) {
251 		error = ENXIO;
252 		goto end;
253 	}
254 	error = 0;
255 	switch (cmd) {
256 	case SIOCSIFMTU:
257 		GRE_WLOCK(sc);
258 		sc->gre_mtu = ifr->ifr_mtu;
259 		gre_updatehdr(sc);
260 		GRE_WUNLOCK(sc);
261 		goto end;
262 	case SIOCSIFPHYADDR:
263 #ifdef INET6
264 	case SIOCSIFPHYADDR_IN6:
265 #endif
266 		error = EINVAL;
267 		switch (cmd) {
268 #ifdef INET
269 		case SIOCSIFPHYADDR:
270 			src = (struct sockaddr *)
271 				&(((struct in_aliasreq *)data)->ifra_addr);
272 			dst = (struct sockaddr *)
273 				&(((struct in_aliasreq *)data)->ifra_dstaddr);
274 			break;
275 #endif
276 #ifdef INET6
277 		case SIOCSIFPHYADDR_IN6:
278 			src = (struct sockaddr *)
279 				&(((struct in6_aliasreq *)data)->ifra_addr);
280 			dst = (struct sockaddr *)
281 				&(((struct in6_aliasreq *)data)->ifra_dstaddr);
282 			break;
283 #endif
284 		default:
285 			error = EAFNOSUPPORT;
286 			goto end;
287 		}
288 		/* sa_family must be equal */
289 		if (src->sa_family != dst->sa_family ||
290 		    src->sa_len != dst->sa_len)
291 			goto end;
292 
293 		/* validate sa_len */
294 		switch (src->sa_family) {
295 #ifdef INET
296 		case AF_INET:
297 			if (src->sa_len != sizeof(struct sockaddr_in))
298 				goto end;
299 			break;
300 #endif
301 #ifdef INET6
302 		case AF_INET6:
303 			if (src->sa_len != sizeof(struct sockaddr_in6))
304 				goto end;
305 			break;
306 #endif
307 		default:
308 			error = EAFNOSUPPORT;
309 			goto end;
310 		}
311 		/* check sa_family looks sane for the cmd */
312 		error = EAFNOSUPPORT;
313 		switch (cmd) {
314 #ifdef INET
315 		case SIOCSIFPHYADDR:
316 			if (src->sa_family == AF_INET)
317 				break;
318 			goto end;
319 #endif
320 #ifdef INET6
321 		case SIOCSIFPHYADDR_IN6:
322 			if (src->sa_family == AF_INET6)
323 				break;
324 			goto end;
325 #endif
326 		}
327 		error = EADDRNOTAVAIL;
328 		switch (src->sa_family) {
329 #ifdef INET
330 		case AF_INET:
331 			if (satosin(src)->sin_addr.s_addr == INADDR_ANY ||
332 			    satosin(dst)->sin_addr.s_addr == INADDR_ANY)
333 				goto end;
334 			break;
335 #endif
336 #ifdef INET6
337 		case AF_INET6:
338 			if (IN6_IS_ADDR_UNSPECIFIED(&satosin6(src)->sin6_addr)
339 			    ||
340 			    IN6_IS_ADDR_UNSPECIFIED(&satosin6(dst)->sin6_addr))
341 				goto end;
342 			/*
343 			 * Check validity of the scope zone ID of the
344 			 * addresses, and convert it into the kernel
345 			 * internal form if necessary.
346 			 */
347 			error = sa6_embedscope(satosin6(src), 0);
348 			if (error != 0)
349 				goto end;
350 			error = sa6_embedscope(satosin6(dst), 0);
351 			if (error != 0)
352 				goto end;
353 #endif
354 		};
355 		error = gre_set_tunnel(ifp, src, dst);
356 		break;
357 	case SIOCDIFPHYADDR:
358 		gre_delete_tunnel(ifp);
359 		break;
360 	case SIOCGIFPSRCADDR:
361 	case SIOCGIFPDSTADDR:
362 #ifdef INET6
363 	case SIOCGIFPSRCADDR_IN6:
364 	case SIOCGIFPDSTADDR_IN6:
365 #endif
366 		if (sc->gre_family == 0) {
367 			error = EADDRNOTAVAIL;
368 			break;
369 		}
370 		GRE_RLOCK(sc);
371 		switch (cmd) {
372 #ifdef INET
373 		case SIOCGIFPSRCADDR:
374 		case SIOCGIFPDSTADDR:
375 			if (sc->gre_family != AF_INET) {
376 				error = EADDRNOTAVAIL;
377 				break;
378 			}
379 			sin = (struct sockaddr_in *)&ifr->ifr_addr;
380 			memset(sin, 0, sizeof(*sin));
381 			sin->sin_family = AF_INET;
382 			sin->sin_len = sizeof(*sin);
383 			break;
384 #endif
385 #ifdef INET6
386 		case SIOCGIFPSRCADDR_IN6:
387 		case SIOCGIFPDSTADDR_IN6:
388 			if (sc->gre_family != AF_INET6) {
389 				error = EADDRNOTAVAIL;
390 				break;
391 			}
392 			sin6 = (struct sockaddr_in6 *)
393 				&(((struct in6_ifreq *)data)->ifr_addr);
394 			memset(sin6, 0, sizeof(*sin6));
395 			sin6->sin6_family = AF_INET6;
396 			sin6->sin6_len = sizeof(*sin6);
397 			break;
398 #endif
399 		}
400 		if (error == 0) {
401 			switch (cmd) {
402 #ifdef INET
403 			case SIOCGIFPSRCADDR:
404 				sin->sin_addr = sc->gre_oip.ip_src;
405 				break;
406 			case SIOCGIFPDSTADDR:
407 				sin->sin_addr = sc->gre_oip.ip_dst;
408 				break;
409 #endif
410 #ifdef INET6
411 			case SIOCGIFPSRCADDR_IN6:
412 				sin6->sin6_addr = sc->gre_oip6.ip6_src;
413 				break;
414 			case SIOCGIFPDSTADDR_IN6:
415 				sin6->sin6_addr = sc->gre_oip6.ip6_dst;
416 				break;
417 #endif
418 			}
419 		}
420 		GRE_RUNLOCK(sc);
421 		if (error != 0)
422 			break;
423 		switch (cmd) {
424 #ifdef INET
425 		case SIOCGIFPSRCADDR:
426 		case SIOCGIFPDSTADDR:
427 			error = prison_if(curthread->td_ucred,
428 			    (struct sockaddr *)sin);
429 			if (error != 0)
430 				memset(sin, 0, sizeof(*sin));
431 			break;
432 #endif
433 #ifdef INET6
434 		case SIOCGIFPSRCADDR_IN6:
435 		case SIOCGIFPDSTADDR_IN6:
436 			error = prison_if(curthread->td_ucred,
437 			    (struct sockaddr *)sin6);
438 			if (error == 0)
439 				error = sa6_recoverscope(sin6);
440 			if (error != 0)
441 				memset(sin6, 0, sizeof(*sin6));
442 #endif
443 		}
444 		break;
445 	case SIOCGTUNFIB:
446 		ifr->ifr_fib = sc->gre_fibnum;
447 		break;
448 	case SIOCSTUNFIB:
449 		if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
450 			break;
451 		if (ifr->ifr_fib >= rt_numfibs)
452 			error = EINVAL;
453 		else
454 			sc->gre_fibnum = ifr->ifr_fib;
455 		break;
456 	case GRESKEY:
457 		if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
458 			break;
459 		if ((error = copyin(ifr->ifr_data, &opt, sizeof(opt))) != 0)
460 			break;
461 		if (sc->gre_key != opt) {
462 			GRE_WLOCK(sc);
463 			sc->gre_key = opt;
464 			gre_updatehdr(sc);
465 			GRE_WUNLOCK(sc);
466 		}
467 		break;
468 	case GREGKEY:
469 		error = copyout(&sc->gre_key, ifr->ifr_data,
470 		    sizeof(sc->gre_key));
471 		break;
472 	case GRESOPTS:
473 		if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
474 			break;
475 		if ((error = copyin(ifr->ifr_data, &opt, sizeof(opt))) != 0)
476 			break;
477 		if (opt & ~GRE_OPTMASK)
478 			error = EINVAL;
479 		else {
480 			if (sc->gre_options != opt) {
481 				GRE_WLOCK(sc);
482 				sc->gre_options = opt;
483 				gre_updatehdr(sc);
484 				GRE_WUNLOCK(sc);
485 			}
486 		}
487 		break;
488 
489 	case GREGOPTS:
490 		error = copyout(&sc->gre_options, ifr->ifr_data,
491 		    sizeof(sc->gre_options));
492 		break;
493 	default:
494 		error = EINVAL;
495 		break;
496 	}
497 end:
498 	sx_xunlock(&gre_ioctl_sx);
499 	return (error);
500 }
501 
502 static void
503 gre_updatehdr(struct gre_softc *sc)
504 {
505 	struct grehdr *gh = NULL;
506 	uint32_t *opts;
507 	uint16_t flags;
508 
509 	GRE_WLOCK_ASSERT(sc);
510 	switch (sc->gre_family) {
511 #ifdef INET
512 	case AF_INET:
513 		sc->gre_hlen = sizeof(struct greip);
514 		sc->gre_oip.ip_v = IPPROTO_IPV4;
515 		sc->gre_oip.ip_hl = sizeof(struct ip) >> 2;
516 		sc->gre_oip.ip_p = IPPROTO_GRE;
517 		gh = &sc->gre_gihdr->gi_gre;
518 		break;
519 #endif
520 #ifdef INET6
521 	case AF_INET6:
522 		sc->gre_hlen = sizeof(struct greip6);
523 		sc->gre_oip6.ip6_vfc = IPV6_VERSION;
524 		sc->gre_oip6.ip6_nxt = IPPROTO_GRE;
525 		gh = &sc->gre_gi6hdr->gi6_gre;
526 		break;
527 #endif
528 	default:
529 		return;
530 	}
531 	flags = 0;
532 	opts = gh->gre_opts;
533 	if (sc->gre_options & GRE_ENABLE_CSUM) {
534 		flags |= GRE_FLAGS_CP;
535 		sc->gre_hlen += 2 * sizeof(uint16_t);
536 		*opts++ = 0;
537 	}
538 	if (sc->gre_key != 0) {
539 		flags |= GRE_FLAGS_KP;
540 		sc->gre_hlen += sizeof(uint32_t);
541 		*opts++ = htonl(sc->gre_key);
542 	}
543 	if (sc->gre_options & GRE_ENABLE_SEQ) {
544 		flags |= GRE_FLAGS_SP;
545 		sc->gre_hlen += sizeof(uint32_t);
546 		*opts++ = 0;
547 	} else
548 		sc->gre_oseq = 0;
549 	gh->gre_flags = htons(flags);
550 	GRE2IFP(sc)->if_mtu = sc->gre_mtu - sc->gre_hlen;
551 }
552 
553 static void
554 gre_detach(struct gre_softc *sc)
555 {
556 
557 	sx_assert(&gre_ioctl_sx, SA_XLOCKED);
558 	if (sc->gre_ecookie != NULL)
559 		encap_detach(sc->gre_ecookie);
560 	sc->gre_ecookie = NULL;
561 }
562 
563 static int
564 gre_set_tunnel(struct ifnet *ifp, struct sockaddr *src,
565     struct sockaddr *dst)
566 {
567 	struct gre_softc *sc, *tsc;
568 #ifdef INET6
569 	struct ip6_hdr *ip6;
570 #endif
571 #ifdef INET
572 	struct ip *ip;
573 #endif
574 	void *hdr;
575 	int error;
576 
577 	sx_assert(&gre_ioctl_sx, SA_XLOCKED);
578 	GRE_LIST_LOCK();
579 	sc = ifp->if_softc;
580 	LIST_FOREACH(tsc, &V_gre_softc_list, gre_list) {
581 		if (tsc == sc || tsc->gre_family != src->sa_family)
582 			continue;
583 #ifdef INET
584 		if (tsc->gre_family == AF_INET &&
585 		    tsc->gre_oip.ip_src.s_addr ==
586 		    satosin(src)->sin_addr.s_addr &&
587 		    tsc->gre_oip.ip_dst.s_addr ==
588 		    satosin(dst)->sin_addr.s_addr) {
589 			GRE_LIST_UNLOCK();
590 			return (EADDRNOTAVAIL);
591 		}
592 #endif
593 #ifdef INET6
594 		if (tsc->gre_family == AF_INET6 &&
595 		    IN6_ARE_ADDR_EQUAL(&tsc->gre_oip6.ip6_src,
596 		    &satosin6(src)->sin6_addr) &&
597 		    IN6_ARE_ADDR_EQUAL(&tsc->gre_oip6.ip6_dst,
598 			&satosin6(dst)->sin6_addr)) {
599 			GRE_LIST_UNLOCK();
600 			return (EADDRNOTAVAIL);
601 		}
602 #endif
603 	}
604 	GRE_LIST_UNLOCK();
605 
606 	switch (src->sa_family) {
607 #ifdef INET
608 	case AF_INET:
609 		hdr = ip = malloc(sizeof(struct greip) +
610 		    3 * sizeof(uint32_t), M_GRE, M_WAITOK | M_ZERO);
611 		ip->ip_src = satosin(src)->sin_addr;
612 		ip->ip_dst = satosin(dst)->sin_addr;
613 		break;
614 #endif
615 #ifdef INET6
616 	case AF_INET6:
617 		hdr = ip6 = malloc(sizeof(struct greip6) +
618 		    3 * sizeof(uint32_t), M_GRE, M_WAITOK | M_ZERO);
619 		ip6->ip6_src = satosin6(src)->sin6_addr;
620 		ip6->ip6_dst = satosin6(dst)->sin6_addr;
621 		break;
622 #endif
623 	default:
624 		return (EAFNOSUPPORT);
625 	}
626 	if (sc->gre_family != src->sa_family)
627 		gre_detach(sc);
628 	GRE_WLOCK(sc);
629 	if (sc->gre_family != 0)
630 		free(sc->gre_hdr, M_GRE);
631 	sc->gre_family = src->sa_family;
632 	sc->gre_hdr = hdr;
633 	sc->gre_oseq = 0;
634 	sc->gre_iseq = UINT32_MAX;
635 	gre_updatehdr(sc);
636 	GRE_WUNLOCK(sc);
637 
638 	error = 0;
639 	switch (src->sa_family) {
640 #ifdef INET
641 	case AF_INET:
642 		error = in_gre_attach(sc);
643 		break;
644 #endif
645 #ifdef INET6
646 	case AF_INET6:
647 		error = in6_gre_attach(sc);
648 		break;
649 #endif
650 	}
651 	if (error == 0)
652 		ifp->if_drv_flags |= IFF_DRV_RUNNING;
653 	return (error);
654 }
655 
656 static void
657 gre_delete_tunnel(struct ifnet *ifp)
658 {
659 	struct gre_softc *sc = ifp->if_softc;
660 	int family;
661 
662 	GRE_WLOCK(sc);
663 	family = sc->gre_family;
664 	sc->gre_family = 0;
665 	GRE_WUNLOCK(sc);
666 	if (family != 0) {
667 		gre_detach(sc);
668 		free(sc->gre_hdr, M_GRE);
669 	}
670 	ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
671 }
672 
673 int
674 gre_input(struct mbuf **mp, int *offp, int proto)
675 {
676 	struct gre_softc *sc;
677 	struct grehdr *gh;
678 	struct ifnet *ifp;
679 	struct mbuf *m;
680 	uint32_t *opts, key;
681 	uint16_t flags;
682 	int hlen, isr, af;
683 
684 	m = *mp;
685 	sc = encap_getarg(m);
686 	KASSERT(sc != NULL, ("encap_getarg returned NULL"));
687 
688 	ifp = GRE2IFP(sc);
689 	gh = (struct grehdr *)mtodo(m, *offp);
690 	flags = ntohs(gh->gre_flags);
691 	if (flags & ~GRE_FLAGS_MASK)
692 		goto drop;
693 	opts = gh->gre_opts;
694 	hlen = 2 * sizeof(uint16_t);
695 	if (flags & GRE_FLAGS_CP) {
696 		/* reserved1 field must be zero */
697 		if (((uint16_t *)opts)[1] != 0)
698 			goto drop;
699 		if (in_cksum_skip(m, m->m_pkthdr.len, *offp) != 0)
700 			goto drop;
701 		hlen += 2 * sizeof(uint16_t);
702 		opts++;
703 	}
704 	if (flags & GRE_FLAGS_KP) {
705 		key = ntohl(*opts);
706 		hlen += sizeof(uint32_t);
707 		opts++;
708 	} else
709 		key = 0;
710 	/*
711 	if (sc->gre_key != 0 && (key != sc->gre_key || key != 0))
712 		goto drop;
713 	*/
714 	if (flags & GRE_FLAGS_SP) {
715 		/* seq = ntohl(*opts); */
716 		hlen += sizeof(uint32_t);
717 	}
718 	switch (ntohs(gh->gre_proto)) {
719 	case ETHERTYPE_WCCP:
720 		/*
721 		 * For WCCP skip an additional 4 bytes if after GRE header
722 		 * doesn't follow an IP header.
723 		 */
724 		if (flags == 0 && (*(uint8_t *)gh->gre_opts & 0xF0) != 0x40)
725 			hlen += sizeof(uint32_t);
726 		/* FALLTHROUGH */
727 	case ETHERTYPE_IP:
728 		isr = NETISR_IP;
729 		af = AF_INET;
730 		break;
731 	case ETHERTYPE_IPV6:
732 		isr = NETISR_IPV6;
733 		af = AF_INET6;
734 		break;
735 	default:
736 		goto drop;
737 	}
738 	m_adj(m, *offp + hlen);
739 	m_clrprotoflags(m);
740 	m->m_pkthdr.rcvif = ifp;
741 	M_SETFIB(m, ifp->if_fib);
742 #ifdef MAC
743 	mac_ifnet_create_mbuf(ifp, m);
744 #endif
745 	BPF_MTAP2(ifp, &af, sizeof(af), m);
746 	if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
747 	if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
748 	if ((ifp->if_flags & IFF_MONITOR) != 0)
749 		m_freem(m);
750 	else
751 		netisr_dispatch(isr, m);
752 	return (IPPROTO_DONE);
753 drop:
754 	if_inc_counter(ifp, IFCOUNTER_IERRORS, 1);
755 	m_freem(m);
756 	return (IPPROTO_DONE);
757 }
758 
759 #define	MTAG_GRE	1307983903
760 static int
761 gre_check_nesting(struct ifnet *ifp, struct mbuf *m)
762 {
763 	struct m_tag *mtag;
764 	int count;
765 
766 	count = 1;
767 	mtag = NULL;
768 	while ((mtag = m_tag_locate(m, MTAG_GRE, 0, mtag)) != NULL) {
769 		if (*(struct ifnet **)(mtag + 1) == ifp) {
770 			log(LOG_NOTICE, "%s: loop detected\n", ifp->if_xname);
771 			return (EIO);
772 		}
773 		count++;
774 	}
775 	if (count > V_max_gre_nesting) {
776 		log(LOG_NOTICE,
777 		    "%s: if_output recursively called too many times(%d)\n",
778 		    ifp->if_xname, count);
779 		return (EIO);
780 	}
781 	mtag = m_tag_alloc(MTAG_GRE, 0, sizeof(struct ifnet *), M_NOWAIT);
782 	if (mtag == NULL)
783 		return (ENOMEM);
784 	*(struct ifnet **)(mtag + 1) = ifp;
785 	m_tag_prepend(m, mtag);
786 	return (0);
787 }
788 
789 static int
790 gre_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
791    struct route *ro)
792 {
793 	uint32_t af;
794 	int error;
795 
796 #ifdef MAC
797 	error = mac_ifnet_check_transmit(ifp, m);
798 	if (error != 0)
799 		goto drop;
800 #endif
801 	if ((ifp->if_flags & IFF_MONITOR) != 0 ||
802 	    (ifp->if_flags & IFF_UP) == 0) {
803 		error = ENETDOWN;
804 		goto drop;
805 	}
806 
807 	error = gre_check_nesting(ifp, m);
808 	if (error != 0)
809 		goto drop;
810 
811 	m->m_flags &= ~(M_BCAST|M_MCAST);
812 	if (dst->sa_family == AF_UNSPEC)
813 		bcopy(dst->sa_data, &af, sizeof(af));
814 	else
815 		af = dst->sa_family;
816 	BPF_MTAP2(ifp, &af, sizeof(af), m);
817 	m->m_pkthdr.csum_data = af;	/* save af for if_transmit */
818 	return (ifp->if_transmit(ifp, m));
819 drop:
820 	m_freem(m);
821 	if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
822 	return (error);
823 }
824 
825 static void
826 gre_setseqn(struct grehdr *gh, uint32_t seq)
827 {
828 	uint32_t *opts;
829 	uint16_t flags;
830 
831 	opts = gh->gre_opts;
832 	flags = ntohs(gh->gre_flags);
833 	KASSERT((flags & GRE_FLAGS_SP) != 0,
834 	    ("gre_setseqn called, but GRE_FLAGS_SP isn't set "));
835 	if (flags & GRE_FLAGS_CP)
836 		opts++;
837 	if (flags & GRE_FLAGS_KP)
838 		opts++;
839 	*opts = htonl(seq);
840 }
841 
842 static int
843 gre_transmit(struct ifnet *ifp, struct mbuf *m)
844 {
845 	GRE_RLOCK_TRACKER;
846 	struct gre_softc *sc;
847 	struct grehdr *gh;
848 	uint32_t iaf, oaf, oseq;
849 	int error, hlen, olen, plen;
850 	int want_seq, want_csum;
851 
852 	plen = 0;
853 	sc = ifp->if_softc;
854 	if (sc == NULL) {
855 		error = ENETDOWN;
856 		m_freem(m);
857 		goto drop;
858 	}
859 	GRE_RLOCK(sc);
860 	if (sc->gre_family == 0) {
861 		GRE_RUNLOCK(sc);
862 		error = ENETDOWN;
863 		m_freem(m);
864 		goto drop;
865 	}
866 	iaf = m->m_pkthdr.csum_data;
867 	oaf = sc->gre_family;
868 	hlen = sc->gre_hlen;
869 	want_seq = (sc->gre_options & GRE_ENABLE_SEQ) != 0;
870 	if (want_seq)
871 		oseq = sc->gre_oseq++; /* XXX */
872 	else
873 		oseq = 0;		/* Make compiler happy. */
874 	want_csum = (sc->gre_options & GRE_ENABLE_CSUM) != 0;
875 	M_SETFIB(m, sc->gre_fibnum);
876 	M_PREPEND(m, hlen, M_NOWAIT);
877 	if (m == NULL) {
878 		GRE_RUNLOCK(sc);
879 		error = ENOBUFS;
880 		goto drop;
881 	}
882 	bcopy(sc->gre_hdr, mtod(m, void *), hlen);
883 	GRE_RUNLOCK(sc);
884 	switch (oaf) {
885 #ifdef INET
886 	case AF_INET:
887 		olen = sizeof(struct ip);
888 		break;
889 #endif
890 #ifdef INET6
891 	case AF_INET6:
892 		olen = sizeof(struct ip6_hdr);
893 		break;
894 #endif
895 	default:
896 		error = ENETDOWN;
897 		goto drop;
898 	}
899 	gh = (struct grehdr *)mtodo(m, olen);
900 	switch (iaf) {
901 #ifdef INET
902 	case AF_INET:
903 		gh->gre_proto = htons(ETHERTYPE_IP);
904 		break;
905 #endif
906 #ifdef INET6
907 	case AF_INET6:
908 		gh->gre_proto = htons(ETHERTYPE_IPV6);
909 		break;
910 #endif
911 	default:
912 		error = ENETDOWN;
913 		goto drop;
914 	}
915 	if (want_seq)
916 		gre_setseqn(gh, oseq);
917 	if (want_csum) {
918 		*(uint16_t *)gh->gre_opts = in_cksum_skip(m,
919 		    m->m_pkthdr.len, olen);
920 	}
921 	plen = m->m_pkthdr.len - hlen;
922 	switch (oaf) {
923 #ifdef INET
924 	case AF_INET:
925 		error = in_gre_output(m, iaf, hlen);
926 		break;
927 #endif
928 #ifdef INET6
929 	case AF_INET6:
930 		error = in6_gre_output(m, iaf, hlen);
931 		break;
932 #endif
933 	default:
934 		m_freem(m);
935 		error = ENETDOWN;
936 	};
937 drop:
938 	if (error)
939 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
940 	else {
941 		if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
942 		if_inc_counter(ifp, IFCOUNTER_OBYTES, plen);
943 	}
944 	return (error);
945 }
946 
947 static void
948 gre_qflush(struct ifnet *ifp __unused)
949 {
950 
951 }
952 
953 static int
954 gremodevent(module_t mod, int type, void *data)
955 {
956 
957 	switch (type) {
958 	case MOD_LOAD:
959 	case MOD_UNLOAD:
960 		break;
961 	default:
962 		return (EOPNOTSUPP);
963 	}
964 	return (0);
965 }
966 
967 static moduledata_t gre_mod = {
968 	"if_gre",
969 	gremodevent,
970 	0
971 };
972 
973 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
974 MODULE_VERSION(if_gre, 1);
975