xref: /freebsd/sys/net/if_gre.c (revision 56e53cb8ef000c3ef72337a4095987a932cdedef)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
5  * Copyright (c) 2014 Andrey V. Elsukov <ae@FreeBSD.org>
6  * All rights reserved.
7  *
8  * This code is derived from software contributed to The NetBSD Foundation
9  * by Heiko W.Rupp <hwr@pilhuhn.de>
10  *
11  * IPv6-over-GRE contributed by Gert Doering <gert@greenie.muc.de>
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
24  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
25  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
26  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
27  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
28  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
29  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
30  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
31  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
32  * POSSIBILITY OF SUCH DAMAGE.
33  *
34  * $NetBSD: if_gre.c,v 1.49 2003/12/11 00:22:29 itojun Exp $
35  */
36 
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
39 
40 #include "opt_inet.h"
41 #include "opt_inet6.h"
42 
43 #include <sys/param.h>
44 #include <sys/jail.h>
45 #include <sys/kernel.h>
46 #include <sys/lock.h>
47 #include <sys/libkern.h>
48 #include <sys/malloc.h>
49 #include <sys/module.h>
50 #include <sys/mbuf.h>
51 #include <sys/priv.h>
52 #include <sys/proc.h>
53 #include <sys/protosw.h>
54 #include <sys/rmlock.h>
55 #include <sys/socket.h>
56 #include <sys/sockio.h>
57 #include <sys/sx.h>
58 #include <sys/sysctl.h>
59 #include <sys/syslog.h>
60 #include <sys/systm.h>
61 
62 #include <net/ethernet.h>
63 #include <net/if.h>
64 #include <net/if_var.h>
65 #include <net/if_clone.h>
66 #include <net/if_types.h>
67 #include <net/netisr.h>
68 #include <net/vnet.h>
69 #include <net/route.h>
70 
71 #include <netinet/in.h>
72 #ifdef INET
73 #include <netinet/in_systm.h>
74 #include <netinet/in_var.h>
75 #include <netinet/ip.h>
76 #include <netinet/ip_var.h>
77 #endif
78 
79 #ifdef INET6
80 #include <netinet/ip6.h>
81 #include <netinet6/in6_var.h>
82 #include <netinet6/ip6_var.h>
83 #include <netinet6/scope6_var.h>
84 #endif
85 
86 #include <netinet/ip_encap.h>
87 #include <net/bpf.h>
88 #include <net/if_gre.h>
89 
90 #include <machine/in_cksum.h>
91 #include <security/mac/mac_framework.h>
92 
93 #define	GREMTU			1476
94 static const char grename[] = "gre";
95 static MALLOC_DEFINE(M_GRE, grename, "Generic Routing Encapsulation");
96 static VNET_DEFINE(struct mtx, gre_mtx);
97 #define	V_gre_mtx	VNET(gre_mtx)
98 #define	GRE_LIST_LOCK_INIT(x)		mtx_init(&V_gre_mtx, "gre_mtx", NULL, \
99 					    MTX_DEF)
100 #define	GRE_LIST_LOCK_DESTROY(x)	mtx_destroy(&V_gre_mtx)
101 #define	GRE_LIST_LOCK(x)		mtx_lock(&V_gre_mtx)
102 #define	GRE_LIST_UNLOCK(x)		mtx_unlock(&V_gre_mtx)
103 
104 static VNET_DEFINE(LIST_HEAD(, gre_softc), gre_softc_list);
105 #define	V_gre_softc_list	VNET(gre_softc_list)
106 static struct sx gre_ioctl_sx;
107 SX_SYSINIT(gre_ioctl_sx, &gre_ioctl_sx, "gre_ioctl");
108 
109 static int	gre_clone_create(struct if_clone *, int, caddr_t);
110 static void	gre_clone_destroy(struct ifnet *);
111 static VNET_DEFINE(struct if_clone *, gre_cloner);
112 #define	V_gre_cloner	VNET(gre_cloner)
113 
114 static void	gre_qflush(struct ifnet *);
115 static int	gre_transmit(struct ifnet *, struct mbuf *);
116 static int	gre_ioctl(struct ifnet *, u_long, caddr_t);
117 static int	gre_output(struct ifnet *, struct mbuf *,
118 		    const struct sockaddr *, struct route *);
119 
120 static void	gre_updatehdr(struct gre_softc *);
121 static int	gre_set_tunnel(struct ifnet *, struct sockaddr *,
122     struct sockaddr *);
123 static void	gre_delete_tunnel(struct ifnet *);
124 
125 SYSCTL_DECL(_net_link);
126 static SYSCTL_NODE(_net_link, IFT_TUNNEL, gre, CTLFLAG_RW, 0,
127     "Generic Routing Encapsulation");
128 #ifndef MAX_GRE_NEST
129 /*
130  * This macro controls the default upper limitation on nesting of gre tunnels.
131  * Since, setting a large value to this macro with a careless configuration
132  * may introduce system crash, we don't allow any nestings by default.
133  * If you need to configure nested gre tunnels, you can define this macro
134  * in your kernel configuration file.  However, if you do so, please be
135  * careful to configure the tunnels so that it won't make a loop.
136  */
137 #define MAX_GRE_NEST 1
138 #endif
139 
140 static VNET_DEFINE(int, max_gre_nesting) = MAX_GRE_NEST;
141 #define	V_max_gre_nesting	VNET(max_gre_nesting)
142 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW | CTLFLAG_VNET,
143     &VNET_NAME(max_gre_nesting), 0, "Max nested tunnels");
144 
145 static void
146 vnet_gre_init(const void *unused __unused)
147 {
148 	LIST_INIT(&V_gre_softc_list);
149 	GRE_LIST_LOCK_INIT();
150 	V_gre_cloner = if_clone_simple(grename, gre_clone_create,
151 	    gre_clone_destroy, 0);
152 }
153 VNET_SYSINIT(vnet_gre_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
154     vnet_gre_init, NULL);
155 
156 static void
157 vnet_gre_uninit(const void *unused __unused)
158 {
159 
160 	if_clone_detach(V_gre_cloner);
161 	GRE_LIST_LOCK_DESTROY();
162 }
163 VNET_SYSUNINIT(vnet_gre_uninit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
164     vnet_gre_uninit, NULL);
165 
166 static int
167 gre_clone_create(struct if_clone *ifc, int unit, caddr_t params)
168 {
169 	struct gre_softc *sc;
170 
171 	sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK | M_ZERO);
172 	sc->gre_fibnum = curthread->td_proc->p_fibnum;
173 	GRE2IFP(sc) = if_alloc(IFT_TUNNEL);
174 	GRE_LOCK_INIT(sc);
175 	GRE2IFP(sc)->if_softc = sc;
176 	if_initname(GRE2IFP(sc), grename, unit);
177 
178 	GRE2IFP(sc)->if_mtu = GREMTU;
179 	GRE2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
180 	GRE2IFP(sc)->if_output = gre_output;
181 	GRE2IFP(sc)->if_ioctl = gre_ioctl;
182 	GRE2IFP(sc)->if_transmit = gre_transmit;
183 	GRE2IFP(sc)->if_qflush = gre_qflush;
184 	GRE2IFP(sc)->if_capabilities |= IFCAP_LINKSTATE;
185 	GRE2IFP(sc)->if_capenable |= IFCAP_LINKSTATE;
186 	if_attach(GRE2IFP(sc));
187 	bpfattach(GRE2IFP(sc), DLT_NULL, sizeof(u_int32_t));
188 	GRE_LIST_LOCK();
189 	LIST_INSERT_HEAD(&V_gre_softc_list, sc, gre_list);
190 	GRE_LIST_UNLOCK();
191 	return (0);
192 }
193 
194 static void
195 gre_clone_destroy(struct ifnet *ifp)
196 {
197 	struct gre_softc *sc;
198 
199 	sx_xlock(&gre_ioctl_sx);
200 	sc = ifp->if_softc;
201 	gre_delete_tunnel(ifp);
202 	GRE_LIST_LOCK();
203 	LIST_REMOVE(sc, gre_list);
204 	GRE_LIST_UNLOCK();
205 	bpfdetach(ifp);
206 	if_detach(ifp);
207 	ifp->if_softc = NULL;
208 	sx_xunlock(&gre_ioctl_sx);
209 
210 	if_free(ifp);
211 	GRE_LOCK_DESTROY(sc);
212 	free(sc, M_GRE);
213 }
214 
215 static int
216 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
217 {
218 	GRE_RLOCK_TRACKER;
219 	struct ifreq *ifr = (struct ifreq *)data;
220 	struct sockaddr *src, *dst;
221 	struct gre_softc *sc;
222 #ifdef INET
223 	struct sockaddr_in *sin = NULL;
224 #endif
225 #ifdef INET6
226 	struct sockaddr_in6 *sin6 = NULL;
227 #endif
228 	uint32_t opt;
229 	int error;
230 
231 	switch (cmd) {
232 	case SIOCSIFMTU:
233 		 /* XXX: */
234 		if (ifr->ifr_mtu < 576)
235 			return (EINVAL);
236 		ifp->if_mtu = ifr->ifr_mtu;
237 		return (0);
238 	case SIOCSIFADDR:
239 		ifp->if_flags |= IFF_UP;
240 	case SIOCSIFFLAGS:
241 	case SIOCADDMULTI:
242 	case SIOCDELMULTI:
243 		return (0);
244 	case GRESADDRS:
245 	case GRESADDRD:
246 	case GREGADDRS:
247 	case GREGADDRD:
248 	case GRESPROTO:
249 	case GREGPROTO:
250 		return (EOPNOTSUPP);
251 	}
252 	src = dst = NULL;
253 	sx_xlock(&gre_ioctl_sx);
254 	sc = ifp->if_softc;
255 	if (sc == NULL) {
256 		error = ENXIO;
257 		goto end;
258 	}
259 	error = 0;
260 	switch (cmd) {
261 	case SIOCSIFPHYADDR:
262 #ifdef INET6
263 	case SIOCSIFPHYADDR_IN6:
264 #endif
265 		error = EINVAL;
266 		switch (cmd) {
267 #ifdef INET
268 		case SIOCSIFPHYADDR:
269 			src = (struct sockaddr *)
270 				&(((struct in_aliasreq *)data)->ifra_addr);
271 			dst = (struct sockaddr *)
272 				&(((struct in_aliasreq *)data)->ifra_dstaddr);
273 			break;
274 #endif
275 #ifdef INET6
276 		case SIOCSIFPHYADDR_IN6:
277 			src = (struct sockaddr *)
278 				&(((struct in6_aliasreq *)data)->ifra_addr);
279 			dst = (struct sockaddr *)
280 				&(((struct in6_aliasreq *)data)->ifra_dstaddr);
281 			break;
282 #endif
283 		default:
284 			error = EAFNOSUPPORT;
285 			goto end;
286 		}
287 		/* sa_family must be equal */
288 		if (src->sa_family != dst->sa_family ||
289 		    src->sa_len != dst->sa_len)
290 			goto end;
291 
292 		/* validate sa_len */
293 		switch (src->sa_family) {
294 #ifdef INET
295 		case AF_INET:
296 			if (src->sa_len != sizeof(struct sockaddr_in))
297 				goto end;
298 			break;
299 #endif
300 #ifdef INET6
301 		case AF_INET6:
302 			if (src->sa_len != sizeof(struct sockaddr_in6))
303 				goto end;
304 			break;
305 #endif
306 		default:
307 			error = EAFNOSUPPORT;
308 			goto end;
309 		}
310 		/* check sa_family looks sane for the cmd */
311 		error = EAFNOSUPPORT;
312 		switch (cmd) {
313 #ifdef INET
314 		case SIOCSIFPHYADDR:
315 			if (src->sa_family == AF_INET)
316 				break;
317 			goto end;
318 #endif
319 #ifdef INET6
320 		case SIOCSIFPHYADDR_IN6:
321 			if (src->sa_family == AF_INET6)
322 				break;
323 			goto end;
324 #endif
325 		}
326 		error = EADDRNOTAVAIL;
327 		switch (src->sa_family) {
328 #ifdef INET
329 		case AF_INET:
330 			if (satosin(src)->sin_addr.s_addr == INADDR_ANY ||
331 			    satosin(dst)->sin_addr.s_addr == INADDR_ANY)
332 				goto end;
333 			break;
334 #endif
335 #ifdef INET6
336 		case AF_INET6:
337 			if (IN6_IS_ADDR_UNSPECIFIED(&satosin6(src)->sin6_addr)
338 			    ||
339 			    IN6_IS_ADDR_UNSPECIFIED(&satosin6(dst)->sin6_addr))
340 				goto end;
341 			/*
342 			 * Check validity of the scope zone ID of the
343 			 * addresses, and convert it into the kernel
344 			 * internal form if necessary.
345 			 */
346 			error = sa6_embedscope(satosin6(src), 0);
347 			if (error != 0)
348 				goto end;
349 			error = sa6_embedscope(satosin6(dst), 0);
350 			if (error != 0)
351 				goto end;
352 #endif
353 		}
354 		error = gre_set_tunnel(ifp, src, dst);
355 		break;
356 	case SIOCDIFPHYADDR:
357 		gre_delete_tunnel(ifp);
358 		break;
359 	case SIOCGIFPSRCADDR:
360 	case SIOCGIFPDSTADDR:
361 #ifdef INET6
362 	case SIOCGIFPSRCADDR_IN6:
363 	case SIOCGIFPDSTADDR_IN6:
364 #endif
365 		if (sc->gre_family == 0) {
366 			error = EADDRNOTAVAIL;
367 			break;
368 		}
369 		GRE_RLOCK(sc);
370 		switch (cmd) {
371 #ifdef INET
372 		case SIOCGIFPSRCADDR:
373 		case SIOCGIFPDSTADDR:
374 			if (sc->gre_family != AF_INET) {
375 				error = EADDRNOTAVAIL;
376 				break;
377 			}
378 			sin = (struct sockaddr_in *)&ifr->ifr_addr;
379 			memset(sin, 0, sizeof(*sin));
380 			sin->sin_family = AF_INET;
381 			sin->sin_len = sizeof(*sin);
382 			break;
383 #endif
384 #ifdef INET6
385 		case SIOCGIFPSRCADDR_IN6:
386 		case SIOCGIFPDSTADDR_IN6:
387 			if (sc->gre_family != AF_INET6) {
388 				error = EADDRNOTAVAIL;
389 				break;
390 			}
391 			sin6 = (struct sockaddr_in6 *)
392 				&(((struct in6_ifreq *)data)->ifr_addr);
393 			memset(sin6, 0, sizeof(*sin6));
394 			sin6->sin6_family = AF_INET6;
395 			sin6->sin6_len = sizeof(*sin6);
396 			break;
397 #endif
398 		}
399 		if (error == 0) {
400 			switch (cmd) {
401 #ifdef INET
402 			case SIOCGIFPSRCADDR:
403 				sin->sin_addr = sc->gre_oip.ip_src;
404 				break;
405 			case SIOCGIFPDSTADDR:
406 				sin->sin_addr = sc->gre_oip.ip_dst;
407 				break;
408 #endif
409 #ifdef INET6
410 			case SIOCGIFPSRCADDR_IN6:
411 				sin6->sin6_addr = sc->gre_oip6.ip6_src;
412 				break;
413 			case SIOCGIFPDSTADDR_IN6:
414 				sin6->sin6_addr = sc->gre_oip6.ip6_dst;
415 				break;
416 #endif
417 			}
418 		}
419 		GRE_RUNLOCK(sc);
420 		if (error != 0)
421 			break;
422 		switch (cmd) {
423 #ifdef INET
424 		case SIOCGIFPSRCADDR:
425 		case SIOCGIFPDSTADDR:
426 			error = prison_if(curthread->td_ucred,
427 			    (struct sockaddr *)sin);
428 			if (error != 0)
429 				memset(sin, 0, sizeof(*sin));
430 			break;
431 #endif
432 #ifdef INET6
433 		case SIOCGIFPSRCADDR_IN6:
434 		case SIOCGIFPDSTADDR_IN6:
435 			error = prison_if(curthread->td_ucred,
436 			    (struct sockaddr *)sin6);
437 			if (error == 0)
438 				error = sa6_recoverscope(sin6);
439 			if (error != 0)
440 				memset(sin6, 0, sizeof(*sin6));
441 #endif
442 		}
443 		break;
444 	case SIOCGTUNFIB:
445 		ifr->ifr_fib = sc->gre_fibnum;
446 		break;
447 	case SIOCSTUNFIB:
448 		if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
449 			break;
450 		if (ifr->ifr_fib >= rt_numfibs)
451 			error = EINVAL;
452 		else
453 			sc->gre_fibnum = ifr->ifr_fib;
454 		break;
455 	case GRESKEY:
456 		if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
457 			break;
458 		if ((error = copyin(ifr->ifr_data, &opt, sizeof(opt))) != 0)
459 			break;
460 		if (sc->gre_key != opt) {
461 			GRE_WLOCK(sc);
462 			sc->gre_key = opt;
463 			gre_updatehdr(sc);
464 			GRE_WUNLOCK(sc);
465 		}
466 		break;
467 	case GREGKEY:
468 		error = copyout(&sc->gre_key, ifr->ifr_data,
469 		    sizeof(sc->gre_key));
470 		break;
471 	case GRESOPTS:
472 		if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
473 			break;
474 		if ((error = copyin(ifr->ifr_data, &opt, sizeof(opt))) != 0)
475 			break;
476 		if (opt & ~GRE_OPTMASK)
477 			error = EINVAL;
478 		else {
479 			if (sc->gre_options != opt) {
480 				GRE_WLOCK(sc);
481 				sc->gre_options = opt;
482 				gre_updatehdr(sc);
483 				GRE_WUNLOCK(sc);
484 			}
485 		}
486 		break;
487 
488 	case GREGOPTS:
489 		error = copyout(&sc->gre_options, ifr->ifr_data,
490 		    sizeof(sc->gre_options));
491 		break;
492 	default:
493 		error = EINVAL;
494 		break;
495 	}
496 end:
497 	sx_xunlock(&gre_ioctl_sx);
498 	return (error);
499 }
500 
501 static void
502 gre_updatehdr(struct gre_softc *sc)
503 {
504 	struct grehdr *gh = NULL;
505 	uint32_t *opts;
506 	uint16_t flags;
507 
508 	GRE_WLOCK_ASSERT(sc);
509 	switch (sc->gre_family) {
510 #ifdef INET
511 	case AF_INET:
512 		sc->gre_hlen = sizeof(struct greip);
513 		sc->gre_oip.ip_v = IPPROTO_IPV4;
514 		sc->gre_oip.ip_hl = sizeof(struct ip) >> 2;
515 		sc->gre_oip.ip_p = IPPROTO_GRE;
516 		gh = &sc->gre_gihdr->gi_gre;
517 		break;
518 #endif
519 #ifdef INET6
520 	case AF_INET6:
521 		sc->gre_hlen = sizeof(struct greip6);
522 		sc->gre_oip6.ip6_vfc = IPV6_VERSION;
523 		sc->gre_oip6.ip6_nxt = IPPROTO_GRE;
524 		gh = &sc->gre_gi6hdr->gi6_gre;
525 		break;
526 #endif
527 	default:
528 		return;
529 	}
530 	flags = 0;
531 	opts = gh->gre_opts;
532 	if (sc->gre_options & GRE_ENABLE_CSUM) {
533 		flags |= GRE_FLAGS_CP;
534 		sc->gre_hlen += 2 * sizeof(uint16_t);
535 		*opts++ = 0;
536 	}
537 	if (sc->gre_key != 0) {
538 		flags |= GRE_FLAGS_KP;
539 		sc->gre_hlen += sizeof(uint32_t);
540 		*opts++ = htonl(sc->gre_key);
541 	}
542 	if (sc->gre_options & GRE_ENABLE_SEQ) {
543 		flags |= GRE_FLAGS_SP;
544 		sc->gre_hlen += sizeof(uint32_t);
545 		*opts++ = 0;
546 	} else
547 		sc->gre_oseq = 0;
548 	gh->gre_flags = htons(flags);
549 }
550 
551 static void
552 gre_detach(struct gre_softc *sc)
553 {
554 
555 	sx_assert(&gre_ioctl_sx, SA_XLOCKED);
556 	if (sc->gre_ecookie != NULL)
557 		encap_detach(sc->gre_ecookie);
558 	sc->gre_ecookie = NULL;
559 }
560 
561 static int
562 gre_set_tunnel(struct ifnet *ifp, struct sockaddr *src,
563     struct sockaddr *dst)
564 {
565 	struct gre_softc *sc, *tsc;
566 #ifdef INET6
567 	struct ip6_hdr *ip6;
568 #endif
569 #ifdef INET
570 	struct ip *ip;
571 #endif
572 	void *hdr;
573 	int error;
574 
575 	sx_assert(&gre_ioctl_sx, SA_XLOCKED);
576 	GRE_LIST_LOCK();
577 	sc = ifp->if_softc;
578 	LIST_FOREACH(tsc, &V_gre_softc_list, gre_list) {
579 		if (tsc == sc || tsc->gre_family != src->sa_family)
580 			continue;
581 #ifdef INET
582 		if (tsc->gre_family == AF_INET &&
583 		    tsc->gre_oip.ip_src.s_addr ==
584 		    satosin(src)->sin_addr.s_addr &&
585 		    tsc->gre_oip.ip_dst.s_addr ==
586 		    satosin(dst)->sin_addr.s_addr) {
587 			GRE_LIST_UNLOCK();
588 			return (EADDRNOTAVAIL);
589 		}
590 #endif
591 #ifdef INET6
592 		if (tsc->gre_family == AF_INET6 &&
593 		    IN6_ARE_ADDR_EQUAL(&tsc->gre_oip6.ip6_src,
594 		    &satosin6(src)->sin6_addr) &&
595 		    IN6_ARE_ADDR_EQUAL(&tsc->gre_oip6.ip6_dst,
596 			&satosin6(dst)->sin6_addr)) {
597 			GRE_LIST_UNLOCK();
598 			return (EADDRNOTAVAIL);
599 		}
600 #endif
601 	}
602 	GRE_LIST_UNLOCK();
603 
604 	switch (src->sa_family) {
605 #ifdef INET
606 	case AF_INET:
607 		hdr = ip = malloc(sizeof(struct greip) +
608 		    3 * sizeof(uint32_t), M_GRE, M_WAITOK | M_ZERO);
609 		ip->ip_src = satosin(src)->sin_addr;
610 		ip->ip_dst = satosin(dst)->sin_addr;
611 		break;
612 #endif
613 #ifdef INET6
614 	case AF_INET6:
615 		hdr = ip6 = malloc(sizeof(struct greip6) +
616 		    3 * sizeof(uint32_t), M_GRE, M_WAITOK | M_ZERO);
617 		ip6->ip6_src = satosin6(src)->sin6_addr;
618 		ip6->ip6_dst = satosin6(dst)->sin6_addr;
619 		break;
620 #endif
621 	default:
622 		return (EAFNOSUPPORT);
623 	}
624 	if (sc->gre_family != 0)
625 		gre_detach(sc);
626 	GRE_WLOCK(sc);
627 	if (sc->gre_family != 0)
628 		free(sc->gre_hdr, M_GRE);
629 	sc->gre_family = src->sa_family;
630 	sc->gre_hdr = hdr;
631 	sc->gre_oseq = 0;
632 	sc->gre_iseq = UINT32_MAX;
633 	gre_updatehdr(sc);
634 	GRE_WUNLOCK(sc);
635 
636 	error = 0;
637 	switch (src->sa_family) {
638 #ifdef INET
639 	case AF_INET:
640 		error = in_gre_attach(sc);
641 		break;
642 #endif
643 #ifdef INET6
644 	case AF_INET6:
645 		error = in6_gre_attach(sc);
646 		break;
647 #endif
648 	}
649 	if (error == 0) {
650 		ifp->if_drv_flags |= IFF_DRV_RUNNING;
651 		if_link_state_change(ifp, LINK_STATE_UP);
652 	}
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 	if_link_state_change(ifp, LINK_STATE_DOWN);
672 }
673 
674 int
675 gre_input(struct mbuf **mp, int *offp, int proto)
676 {
677 	struct gre_softc *sc;
678 	struct grehdr *gh;
679 	struct ifnet *ifp;
680 	struct mbuf *m;
681 	uint32_t *opts;
682 #ifdef notyet
683 	uint32_t key;
684 #endif
685 	uint16_t flags;
686 	int hlen, isr, af;
687 
688 	m = *mp;
689 	sc = encap_getarg(m);
690 	KASSERT(sc != NULL, ("encap_getarg returned NULL"));
691 
692 	ifp = GRE2IFP(sc);
693 	hlen = *offp + sizeof(struct grehdr) + 4 * sizeof(uint32_t);
694 	if (m->m_pkthdr.len < hlen)
695 		goto drop;
696 	if (m->m_len < hlen) {
697 		m = m_pullup(m, hlen);
698 		if (m == NULL)
699 			goto drop;
700 	}
701 	gh = (struct grehdr *)mtodo(m, *offp);
702 	flags = ntohs(gh->gre_flags);
703 	if (flags & ~GRE_FLAGS_MASK)
704 		goto drop;
705 	opts = gh->gre_opts;
706 	hlen = 2 * sizeof(uint16_t);
707 	if (flags & GRE_FLAGS_CP) {
708 		/* reserved1 field must be zero */
709 		if (((uint16_t *)opts)[1] != 0)
710 			goto drop;
711 		if (in_cksum_skip(m, m->m_pkthdr.len, *offp) != 0)
712 			goto drop;
713 		hlen += 2 * sizeof(uint16_t);
714 		opts++;
715 	}
716 	if (flags & GRE_FLAGS_KP) {
717 #ifdef notyet
718         /*
719          * XXX: The current implementation uses the key only for outgoing
720          * packets. But we can check the key value here, or even in the
721          * encapcheck function.
722          */
723 		key = ntohl(*opts);
724 #endif
725 		hlen += sizeof(uint32_t);
726 		opts++;
727     }
728 #ifdef notyet
729 	} else
730 		key = 0;
731 
732 	if (sc->gre_key != 0 && (key != sc->gre_key || key != 0))
733 		goto drop;
734 #endif
735 	if (flags & GRE_FLAGS_SP) {
736 #ifdef notyet
737 		seq = ntohl(*opts);
738 #endif
739 		hlen += sizeof(uint32_t);
740 	}
741 	switch (ntohs(gh->gre_proto)) {
742 	case ETHERTYPE_WCCP:
743 		/*
744 		 * For WCCP skip an additional 4 bytes if after GRE header
745 		 * doesn't follow an IP header.
746 		 */
747 		if (flags == 0 && (*(uint8_t *)gh->gre_opts & 0xF0) != 0x40)
748 			hlen += sizeof(uint32_t);
749 		/* FALLTHROUGH */
750 	case ETHERTYPE_IP:
751 		isr = NETISR_IP;
752 		af = AF_INET;
753 		break;
754 	case ETHERTYPE_IPV6:
755 		isr = NETISR_IPV6;
756 		af = AF_INET6;
757 		break;
758 	default:
759 		goto drop;
760 	}
761 	m_adj(m, *offp + hlen);
762 	m_clrprotoflags(m);
763 	m->m_pkthdr.rcvif = ifp;
764 	M_SETFIB(m, ifp->if_fib);
765 #ifdef MAC
766 	mac_ifnet_create_mbuf(ifp, m);
767 #endif
768 	BPF_MTAP2(ifp, &af, sizeof(af), m);
769 	if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
770 	if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
771 	if ((ifp->if_flags & IFF_MONITOR) != 0)
772 		m_freem(m);
773 	else
774 		netisr_dispatch(isr, m);
775 	return (IPPROTO_DONE);
776 drop:
777 	if_inc_counter(ifp, IFCOUNTER_IERRORS, 1);
778 	m_freem(m);
779 	return (IPPROTO_DONE);
780 }
781 
782 #define	MTAG_GRE	1307983903
783 static int
784 gre_check_nesting(struct ifnet *ifp, struct mbuf *m)
785 {
786 	struct m_tag *mtag;
787 	int count;
788 
789 	count = 1;
790 	mtag = NULL;
791 	while ((mtag = m_tag_locate(m, MTAG_GRE, 0, mtag)) != NULL) {
792 		if (*(struct ifnet **)(mtag + 1) == ifp) {
793 			log(LOG_NOTICE, "%s: loop detected\n", ifp->if_xname);
794 			return (EIO);
795 		}
796 		count++;
797 	}
798 	if (count > V_max_gre_nesting) {
799 		log(LOG_NOTICE,
800 		    "%s: if_output recursively called too many times(%d)\n",
801 		    ifp->if_xname, count);
802 		return (EIO);
803 	}
804 	mtag = m_tag_alloc(MTAG_GRE, 0, sizeof(struct ifnet *), M_NOWAIT);
805 	if (mtag == NULL)
806 		return (ENOMEM);
807 	*(struct ifnet **)(mtag + 1) = ifp;
808 	m_tag_prepend(m, mtag);
809 	return (0);
810 }
811 
812 static int
813 gre_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
814    struct route *ro)
815 {
816 	uint32_t af;
817 	int error;
818 
819 #ifdef MAC
820 	error = mac_ifnet_check_transmit(ifp, m);
821 	if (error != 0)
822 		goto drop;
823 #endif
824 	if ((ifp->if_flags & IFF_MONITOR) != 0 ||
825 	    (ifp->if_flags & IFF_UP) == 0) {
826 		error = ENETDOWN;
827 		goto drop;
828 	}
829 
830 	error = gre_check_nesting(ifp, m);
831 	if (error != 0)
832 		goto drop;
833 
834 	m->m_flags &= ~(M_BCAST|M_MCAST);
835 	if (dst->sa_family == AF_UNSPEC)
836 		bcopy(dst->sa_data, &af, sizeof(af));
837 	else
838 		af = dst->sa_family;
839 	BPF_MTAP2(ifp, &af, sizeof(af), m);
840 	m->m_pkthdr.csum_data = af;	/* save af for if_transmit */
841 	return (ifp->if_transmit(ifp, m));
842 drop:
843 	m_freem(m);
844 	if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
845 	return (error);
846 }
847 
848 static void
849 gre_setseqn(struct grehdr *gh, uint32_t seq)
850 {
851 	uint32_t *opts;
852 	uint16_t flags;
853 
854 	opts = gh->gre_opts;
855 	flags = ntohs(gh->gre_flags);
856 	KASSERT((flags & GRE_FLAGS_SP) != 0,
857 	    ("gre_setseqn called, but GRE_FLAGS_SP isn't set "));
858 	if (flags & GRE_FLAGS_CP)
859 		opts++;
860 	if (flags & GRE_FLAGS_KP)
861 		opts++;
862 	*opts = htonl(seq);
863 }
864 
865 static int
866 gre_transmit(struct ifnet *ifp, struct mbuf *m)
867 {
868 	GRE_RLOCK_TRACKER;
869 	struct gre_softc *sc;
870 	struct grehdr *gh;
871 	uint32_t iaf, oaf, oseq;
872 	int error, hlen, olen, plen;
873 	int want_seq, want_csum;
874 
875 	plen = 0;
876 	sc = ifp->if_softc;
877 	if (sc == NULL) {
878 		error = ENETDOWN;
879 		m_freem(m);
880 		goto drop;
881 	}
882 	GRE_RLOCK(sc);
883 	if (sc->gre_family == 0) {
884 		GRE_RUNLOCK(sc);
885 		error = ENETDOWN;
886 		m_freem(m);
887 		goto drop;
888 	}
889 	iaf = m->m_pkthdr.csum_data;
890 	oaf = sc->gre_family;
891 	hlen = sc->gre_hlen;
892 	want_seq = (sc->gre_options & GRE_ENABLE_SEQ) != 0;
893 	if (want_seq)
894 		oseq = sc->gre_oseq++; /* XXX */
895 	else
896 		oseq = 0;		/* Make compiler happy. */
897 	want_csum = (sc->gre_options & GRE_ENABLE_CSUM) != 0;
898 	M_SETFIB(m, sc->gre_fibnum);
899 	M_PREPEND(m, hlen, M_NOWAIT);
900 	if (m == NULL) {
901 		GRE_RUNLOCK(sc);
902 		error = ENOBUFS;
903 		goto drop;
904 	}
905 	bcopy(sc->gre_hdr, mtod(m, void *), hlen);
906 	GRE_RUNLOCK(sc);
907 	switch (oaf) {
908 #ifdef INET
909 	case AF_INET:
910 		olen = sizeof(struct ip);
911 		break;
912 #endif
913 #ifdef INET6
914 	case AF_INET6:
915 		olen = sizeof(struct ip6_hdr);
916 		break;
917 #endif
918 	default:
919 		error = ENETDOWN;
920 		goto drop;
921 	}
922 	gh = (struct grehdr *)mtodo(m, olen);
923 	switch (iaf) {
924 #ifdef INET
925 	case AF_INET:
926 		gh->gre_proto = htons(ETHERTYPE_IP);
927 		break;
928 #endif
929 #ifdef INET6
930 	case AF_INET6:
931 		gh->gre_proto = htons(ETHERTYPE_IPV6);
932 		break;
933 #endif
934 	default:
935 		error = ENETDOWN;
936 		goto drop;
937 	}
938 	if (want_seq)
939 		gre_setseqn(gh, oseq);
940 	if (want_csum) {
941 		*(uint16_t *)gh->gre_opts = in_cksum_skip(m,
942 		    m->m_pkthdr.len, olen);
943 	}
944 	plen = m->m_pkthdr.len - hlen;
945 	switch (oaf) {
946 #ifdef INET
947 	case AF_INET:
948 		error = in_gre_output(m, iaf, hlen);
949 		break;
950 #endif
951 #ifdef INET6
952 	case AF_INET6:
953 		error = in6_gre_output(m, iaf, hlen);
954 		break;
955 #endif
956 	default:
957 		m_freem(m);
958 		error = ENETDOWN;
959 	}
960 drop:
961 	if (error)
962 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
963 	else {
964 		if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
965 		if_inc_counter(ifp, IFCOUNTER_OBYTES, plen);
966 	}
967 	return (error);
968 }
969 
970 static void
971 gre_qflush(struct ifnet *ifp __unused)
972 {
973 
974 }
975 
976 static int
977 gremodevent(module_t mod, int type, void *data)
978 {
979 
980 	switch (type) {
981 	case MOD_LOAD:
982 	case MOD_UNLOAD:
983 		break;
984 	default:
985 		return (EOPNOTSUPP);
986 	}
987 	return (0);
988 }
989 
990 static moduledata_t gre_mod = {
991 	"if_gre",
992 	gremodevent,
993 	0
994 };
995 
996 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
997 MODULE_VERSION(if_gre, 1);
998