if_me.c revision 284073
1/*-
2 * Copyright (c) 2014 Andrey V. Elsukov <ae@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: stable/10/sys/net/if_me.c 284073 2015-06-06 13:29:41Z ae $");
29
30#include <sys/param.h>
31#include <sys/jail.h>
32#include <sys/kernel.h>
33#include <sys/lock.h>
34#include <sys/libkern.h>
35#include <sys/malloc.h>
36#include <sys/module.h>
37#include <sys/mbuf.h>
38#include <sys/priv.h>
39#include <sys/proc.h>
40#include <sys/protosw.h>
41#include <sys/rmlock.h>
42#include <sys/socket.h>
43#include <sys/sockio.h>
44#include <sys/sx.h>
45#include <sys/sysctl.h>
46#include <sys/syslog.h>
47#include <sys/systm.h>
48
49#include <net/bpf.h>
50#include <net/ethernet.h>
51#include <net/if.h>
52#include <net/if_var.h>
53#include <net/if_clone.h>
54#include <net/if_types.h>
55#include <net/netisr.h>
56#include <net/vnet.h>
57
58#include <netinet/in.h>
59#include <netinet/in_systm.h>
60#include <netinet/in_var.h>
61#include <netinet/ip.h>
62#include <netinet/ip_var.h>
63#include <netinet/ip_encap.h>
64
65#include <machine/in_cksum.h>
66#include <security/mac/mac_framework.h>
67
68#define	MEMTU			1500
69static const char mename[] = "me";
70static MALLOC_DEFINE(M_IFME, mename, "Minimal Encapsulation for IP");
71static VNET_DEFINE(struct mtx, me_mtx);
72#define	V_me_mtx	VNET(me_mtx)
73/* Minimal forwarding header RFC 2004 */
74struct mobhdr {
75	uint8_t		mob_proto;	/* protocol */
76	uint8_t		mob_flags;	/* flags */
77#define	MOB_FLAGS_SP	0x80		/* source present */
78	uint16_t	mob_csum;	/* header checksum */
79	struct in_addr	mob_dst;	/* original destination address */
80	struct in_addr	mob_src;	/* original source addr (optional) */
81} __packed;
82
83struct me_softc {
84	struct ifnet		*me_ifp;
85	LIST_ENTRY(me_softc)	me_list;
86	struct rmlock		me_lock;
87	u_int			me_fibnum;
88	const struct encaptab	*me_ecookie;
89	struct in_addr		me_src;
90	struct in_addr		me_dst;
91};
92#define	ME2IFP(sc)		((sc)->me_ifp)
93#define	ME_READY(sc)		((sc)->me_src.s_addr != 0)
94#define	ME_LOCK_INIT(sc)	rm_init(&(sc)->me_lock, "me softc")
95#define	ME_LOCK_DESTROY(sc)	rm_destroy(&(sc)->me_lock)
96#define	ME_RLOCK_TRACKER	struct rm_priotracker me_tracker
97#define	ME_RLOCK(sc)		rm_rlock(&(sc)->me_lock, &me_tracker)
98#define	ME_RUNLOCK(sc)		rm_runlock(&(sc)->me_lock, &me_tracker)
99#define	ME_RLOCK_ASSERT(sc)	rm_assert(&(sc)->me_lock, RA_RLOCKED)
100#define	ME_WLOCK(sc)		rm_wlock(&(sc)->me_lock)
101#define	ME_WUNLOCK(sc)		rm_wunlock(&(sc)->me_lock)
102#define	ME_WLOCK_ASSERT(sc)	rm_assert(&(sc)->me_lock, RA_WLOCKED)
103
104#define	ME_LIST_LOCK_INIT(x)	mtx_init(&V_me_mtx, "me_mtx", NULL, MTX_DEF)
105#define	ME_LIST_LOCK_DESTROY(x)	mtx_destroy(&V_me_mtx)
106#define	ME_LIST_LOCK(x)		mtx_lock(&V_me_mtx)
107#define	ME_LIST_UNLOCK(x)	mtx_unlock(&V_me_mtx)
108
109static VNET_DEFINE(LIST_HEAD(, me_softc), me_softc_list);
110#define	V_me_softc_list	VNET(me_softc_list)
111static struct sx me_ioctl_sx;
112SX_SYSINIT(me_ioctl_sx, &me_ioctl_sx, "me_ioctl");
113
114static int	me_clone_create(struct if_clone *, int, caddr_t);
115static void	me_clone_destroy(struct ifnet *);
116static VNET_DEFINE(struct if_clone *, me_cloner);
117#define	V_me_cloner	VNET(me_cloner)
118
119static void	me_qflush(struct ifnet *);
120static int	me_transmit(struct ifnet *, struct mbuf *);
121static int	me_ioctl(struct ifnet *, u_long, caddr_t);
122static int	me_output(struct ifnet *, struct mbuf *,
123		    const struct sockaddr *, struct route *);
124static int	me_input(struct mbuf **, int *, int);
125
126static int	me_set_tunnel(struct ifnet *, struct sockaddr_in *,
127    struct sockaddr_in *);
128static void	me_delete_tunnel(struct ifnet *);
129
130SYSCTL_DECL(_net_link);
131static SYSCTL_NODE(_net_link, IFT_TUNNEL, me, CTLFLAG_RW, 0,
132    "Minimal Encapsulation for IP (RFC 2004)");
133#ifndef MAX_ME_NEST
134#define MAX_ME_NEST 1
135#endif
136
137static VNET_DEFINE(int, max_me_nesting) = MAX_ME_NEST;
138#define	V_max_me_nesting	VNET(max_me_nesting)
139SYSCTL_INT(_net_link_me, OID_AUTO, max_nesting, CTLFLAG_RW | CTLFLAG_VNET,
140    &VNET_NAME(max_me_nesting), 0, "Max nested tunnels");
141
142extern struct domain inetdomain;
143static void me_input10(struct mbuf *, int);
144static const struct protosw in_mobile_protosw = {
145	.pr_type =		SOCK_RAW,
146	.pr_domain =		&inetdomain,
147	.pr_protocol =		IPPROTO_MOBILE,
148	.pr_flags =		PR_ATOMIC|PR_ADDR,
149	.pr_input =		me_input10,
150	.pr_output =		(pr_output_t *)rip_output,
151	.pr_ctlinput =		rip_ctlinput,
152	.pr_ctloutput =		rip_ctloutput,
153	.pr_usrreqs =		&rip_usrreqs
154};
155
156static void
157vnet_me_init(const void *unused __unused)
158{
159	LIST_INIT(&V_me_softc_list);
160	ME_LIST_LOCK_INIT();
161	V_me_cloner = if_clone_simple(mename, me_clone_create,
162	    me_clone_destroy, 0);
163}
164VNET_SYSINIT(vnet_me_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
165    vnet_me_init, NULL);
166
167static void
168vnet_me_uninit(const void *unused __unused)
169{
170
171	if_clone_detach(V_me_cloner);
172	ME_LIST_LOCK_DESTROY();
173}
174VNET_SYSUNINIT(vnet_me_uninit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
175    vnet_me_uninit, NULL);
176
177static int
178me_clone_create(struct if_clone *ifc, int unit, caddr_t params)
179{
180	struct me_softc *sc;
181
182	sc = malloc(sizeof(struct me_softc), M_IFME, M_WAITOK | M_ZERO);
183	sc->me_fibnum = curthread->td_proc->p_fibnum;
184	ME2IFP(sc) = if_alloc(IFT_TUNNEL);
185	ME_LOCK_INIT(sc);
186	ME2IFP(sc)->if_softc = sc;
187	if_initname(ME2IFP(sc), mename, unit);
188
189	ME2IFP(sc)->if_mtu = MEMTU - sizeof(struct mobhdr);
190	ME2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
191	ME2IFP(sc)->if_output = me_output;
192	ME2IFP(sc)->if_ioctl = me_ioctl;
193	ME2IFP(sc)->if_transmit = me_transmit;
194	ME2IFP(sc)->if_qflush = me_qflush;
195	if_attach(ME2IFP(sc));
196	bpfattach(ME2IFP(sc), DLT_NULL, sizeof(u_int32_t));
197	ME_LIST_LOCK();
198	LIST_INSERT_HEAD(&V_me_softc_list, sc, me_list);
199	ME_LIST_UNLOCK();
200	return (0);
201}
202
203static void
204me_clone_destroy(struct ifnet *ifp)
205{
206	struct me_softc *sc;
207
208	sx_xlock(&me_ioctl_sx);
209	sc = ifp->if_softc;
210	me_delete_tunnel(ifp);
211	ME_LIST_LOCK();
212	LIST_REMOVE(sc, me_list);
213	ME_LIST_UNLOCK();
214	bpfdetach(ifp);
215	if_detach(ifp);
216	ifp->if_softc = NULL;
217	sx_xunlock(&me_ioctl_sx);
218
219	if_free(ifp);
220	ME_LOCK_DESTROY(sc);
221	free(sc, M_IFME);
222}
223
224static int
225me_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
226{
227	ME_RLOCK_TRACKER;
228	struct ifreq *ifr = (struct ifreq *)data;
229	struct sockaddr_in *src, *dst;
230	struct me_softc *sc;
231	int error;
232
233	switch (cmd) {
234	case SIOCSIFMTU:
235		if (ifr->ifr_mtu < 576)
236			return (EINVAL);
237		ifp->if_mtu = ifr->ifr_mtu - sizeof(struct mobhdr);
238		return (0);
239	case SIOCSIFADDR:
240		ifp->if_flags |= IFF_UP;
241	case SIOCSIFFLAGS:
242	case SIOCADDMULTI:
243	case SIOCDELMULTI:
244		return (0);
245	}
246	sx_xlock(&me_ioctl_sx);
247	sc = ifp->if_softc;
248	if (sc == NULL) {
249		error = ENXIO;
250		goto end;
251	}
252	error = 0;
253	switch (cmd) {
254	case SIOCSIFPHYADDR:
255		src = (struct sockaddr_in *)
256			&(((struct in_aliasreq *)data)->ifra_addr);
257		dst = (struct sockaddr_in *)
258			&(((struct in_aliasreq *)data)->ifra_dstaddr);
259		if (src->sin_family != dst->sin_family ||
260		    src->sin_family != AF_INET ||
261		    src->sin_len != dst->sin_len ||
262		    src->sin_len != sizeof(struct sockaddr_in)) {
263			error = EINVAL;
264			break;
265		}
266		if (src->sin_addr.s_addr == INADDR_ANY ||
267		    dst->sin_addr.s_addr == INADDR_ANY) {
268			error = EADDRNOTAVAIL;
269			break;
270		}
271		error = me_set_tunnel(ifp, src, dst);
272		break;
273	case SIOCDIFPHYADDR:
274		me_delete_tunnel(ifp);
275		break;
276	case SIOCGIFPSRCADDR:
277	case SIOCGIFPDSTADDR:
278		ME_RLOCK(sc);
279		if (!ME_READY(sc)) {
280			error = EADDRNOTAVAIL;
281			ME_RUNLOCK(sc);
282			break;
283		}
284		src = (struct sockaddr_in *)&ifr->ifr_addr;
285		memset(src, 0, sizeof(*src));
286		src->sin_family = AF_INET;
287		src->sin_len = sizeof(*src);
288		switch (cmd) {
289		case SIOCGIFPSRCADDR:
290			src->sin_addr = sc->me_src;
291			break;
292		case SIOCGIFPDSTADDR:
293			src->sin_addr = sc->me_dst;
294			break;
295		}
296		ME_RUNLOCK(sc);
297		error = prison_if(curthread->td_ucred, sintosa(src));
298		if (error != 0)
299			memset(src, 0, sizeof(*src));
300		break;
301	default:
302		error = EINVAL;
303		break;
304	}
305end:
306	sx_xunlock(&me_ioctl_sx);
307	return (error);
308}
309
310static int
311me_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
312{
313	ME_RLOCK_TRACKER;
314	struct me_softc *sc;
315	struct ip *ip;
316	int ret;
317
318	sc = (struct me_softc *)arg;
319	if ((ME2IFP(sc)->if_flags & IFF_UP) == 0)
320		return (0);
321
322	M_ASSERTPKTHDR(m);
323
324	if (m->m_pkthdr.len < sizeof(struct ip) + sizeof(struct mobhdr) -
325	    sizeof(struct in_addr))
326		return (0);
327
328	ret = 0;
329	ME_RLOCK(sc);
330	if (ME_READY(sc)) {
331		ip = mtod(m, struct ip *);
332		if (sc->me_src.s_addr == ip->ip_dst.s_addr &&
333		    sc->me_dst.s_addr == ip->ip_src.s_addr)
334			ret = 32 * 2;
335	}
336	ME_RUNLOCK(sc);
337	return (ret);
338}
339
340static int
341me_set_tunnel(struct ifnet *ifp, struct sockaddr_in *src,
342    struct sockaddr_in *dst)
343{
344	struct me_softc *sc, *tsc;
345
346	sx_assert(&me_ioctl_sx, SA_XLOCKED);
347	ME_LIST_LOCK();
348	sc = ifp->if_softc;
349	LIST_FOREACH(tsc, &V_me_softc_list, me_list) {
350		if (tsc == sc || !ME_READY(tsc))
351			continue;
352		if (tsc->me_src.s_addr == src->sin_addr.s_addr &&
353		    tsc->me_dst.s_addr == dst->sin_addr.s_addr) {
354			ME_LIST_UNLOCK();
355			return (EADDRNOTAVAIL);
356		}
357	}
358	ME_LIST_UNLOCK();
359
360	ME_WLOCK(sc);
361	sc->me_dst = dst->sin_addr;
362	sc->me_src = src->sin_addr;
363	ME_WUNLOCK(sc);
364
365	if (sc->me_ecookie == NULL)
366		sc->me_ecookie = encap_attach_func(AF_INET, IPPROTO_MOBILE,
367		    me_encapcheck, &in_mobile_protosw, sc);
368	if (sc->me_ecookie != NULL)
369		ifp->if_drv_flags |= IFF_DRV_RUNNING;
370	return (0);
371}
372
373static void
374me_delete_tunnel(struct ifnet *ifp)
375{
376	struct me_softc *sc = ifp->if_softc;
377
378	sx_assert(&me_ioctl_sx, SA_XLOCKED);
379	if (sc->me_ecookie != NULL)
380		encap_detach(sc->me_ecookie);
381	sc->me_ecookie = NULL;
382	ME_WLOCK(sc);
383	sc->me_src.s_addr = 0;
384	sc->me_dst.s_addr = 0;
385	ME_WUNLOCK(sc);
386	ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
387}
388
389static uint16_t
390me_in_cksum(uint16_t *p, int nwords)
391{
392	uint32_t sum = 0;
393
394	while (nwords-- > 0)
395		sum += *p++;
396	sum = (sum >> 16) + (sum & 0xffff);
397	sum += (sum >> 16);
398	return (~sum);
399}
400
401static void
402me_input10(struct mbuf *m, int off)
403{
404	int proto;
405
406	proto = (mtod(m, struct ip *))->ip_p;
407	me_input(&m, &off, proto);
408}
409
410int
411me_input(struct mbuf **mp, int *offp, int proto)
412{
413	struct me_softc *sc;
414	struct mobhdr *mh;
415	struct ifnet *ifp;
416	struct mbuf *m;
417	struct ip *ip;
418	int hlen;
419
420	m = *mp;
421	sc = encap_getarg(m);
422	KASSERT(sc != NULL, ("encap_getarg returned NULL"));
423
424	ifp = ME2IFP(sc);
425	/* checks for short packets */
426	hlen = sizeof(struct mobhdr);
427	if (m->m_pkthdr.len < sizeof(struct ip) + hlen)
428		hlen -= sizeof(struct in_addr);
429	if (m->m_len < sizeof(struct ip) + hlen)
430		m = m_pullup(m, sizeof(struct ip) + hlen);
431	if (m == NULL)
432		goto drop;
433	mh = (struct mobhdr *)mtodo(m, sizeof(struct ip));
434	/* check for wrong flags */
435	if (mh->mob_flags & (~MOB_FLAGS_SP)) {
436		m_freem(m);
437		goto drop;
438	}
439	if (mh->mob_flags) {
440	       if (hlen != sizeof(struct mobhdr)) {
441			m_freem(m);
442			goto drop;
443	       }
444	} else
445		hlen = sizeof(struct mobhdr) - sizeof(struct in_addr);
446	/* check mobile header checksum */
447	if (me_in_cksum((uint16_t *)mh, hlen / sizeof(uint16_t)) != 0) {
448		m_freem(m);
449		goto drop;
450	}
451#ifdef MAC
452	mac_ifnet_create_mbuf(ifp, m);
453#endif
454	ip = mtod(m, struct ip *);
455	ip->ip_dst = mh->mob_dst;
456	ip->ip_p = mh->mob_proto;
457	ip->ip_sum = 0;
458	ip->ip_len = htons(m->m_pkthdr.len - hlen);
459	if (mh->mob_flags)
460		ip->ip_src = mh->mob_src;
461	memmove(mtodo(m, hlen), ip, sizeof(struct ip));
462	m_adj(m, hlen);
463	m_clrprotoflags(m);
464	m->m_pkthdr.rcvif = ifp;
465	m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
466	M_SETFIB(m, sc->me_fibnum);
467	hlen = AF_INET;
468	BPF_MTAP2(ifp, &hlen, sizeof(hlen), m);
469	if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
470	if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
471	if ((ifp->if_flags & IFF_MONITOR) != 0)
472		m_freem(m);
473	else
474		netisr_dispatch(NETISR_IP, m);
475	return (IPPROTO_DONE);
476drop:
477	if_inc_counter(ifp, IFCOUNTER_IERRORS, 1);
478	return (IPPROTO_DONE);
479}
480
481#define	MTAG_ME	1414491977
482static int
483me_check_nesting(struct ifnet *ifp, struct mbuf *m)
484{
485	struct m_tag *mtag;
486	int count;
487
488	count = 1;
489	mtag = NULL;
490	while ((mtag = m_tag_locate(m, MTAG_ME, 0, mtag)) != NULL) {
491		if (*(struct ifnet **)(mtag + 1) == ifp) {
492			log(LOG_NOTICE, "%s: loop detected\n", ifp->if_xname);
493			return (EIO);
494		}
495		count++;
496	}
497	if (count > V_max_me_nesting) {
498		log(LOG_NOTICE,
499		    "%s: if_output recursively called too many times(%d)\n",
500		    ifp->if_xname, count);
501		return (EIO);
502	}
503	mtag = m_tag_alloc(MTAG_ME, 0, sizeof(struct ifnet *), M_NOWAIT);
504	if (mtag == NULL)
505		return (ENOMEM);
506	*(struct ifnet **)(mtag + 1) = ifp;
507	m_tag_prepend(m, mtag);
508	return (0);
509}
510
511static int
512me_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
513   struct route *ro)
514{
515	uint32_t af;
516	int error;
517
518#ifdef MAC
519	error = mac_ifnet_check_transmit(ifp, m);
520	if (error != 0)
521		goto drop;
522#endif
523	if ((ifp->if_flags & IFF_MONITOR) != 0 ||
524	    (ifp->if_flags & IFF_UP) == 0) {
525		error = ENETDOWN;
526		goto drop;
527	}
528
529	error = me_check_nesting(ifp, m);
530	if (error != 0)
531		goto drop;
532
533	m->m_flags &= ~(M_BCAST|M_MCAST);
534	if (dst->sa_family == AF_UNSPEC)
535		bcopy(dst->sa_data, &af, sizeof(af));
536	else
537		af = dst->sa_family;
538	if (af != AF_INET) {
539		error = EAFNOSUPPORT;
540		goto drop;
541	}
542	BPF_MTAP2(ifp, &af, sizeof(af), m);
543	return (ifp->if_transmit(ifp, m));
544drop:
545	m_freem(m);
546	if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
547	return (error);
548}
549
550static int
551me_transmit(struct ifnet *ifp, struct mbuf *m)
552{
553	ME_RLOCK_TRACKER;
554	struct mobhdr mh;
555	struct me_softc *sc;
556	struct ip *ip;
557	int error, hlen, plen;
558
559	sc = ifp->if_softc;
560	if (sc == NULL) {
561		error = ENETDOWN;
562		m_freem(m);
563		goto drop;
564	}
565	if (m->m_len < sizeof(struct ip))
566		m = m_pullup(m, sizeof(struct ip));
567	if (m == NULL) {
568		error = ENOBUFS;
569		goto drop;
570	}
571	ip = mtod(m, struct ip *);
572	/* Fragmented datagramms shouldn't be encapsulated */
573	if (ip->ip_off & htons(IP_MF | IP_OFFMASK)) {
574		error = EINVAL;
575		m_freem(m);
576		goto drop;
577	}
578	mh.mob_proto = ip->ip_p;
579	mh.mob_src = ip->ip_src;
580	mh.mob_dst = ip->ip_dst;
581	ME_RLOCK(sc);
582	if (!ME_READY(sc)) {
583		ME_RUNLOCK(sc);
584		error = ENETDOWN;
585		m_freem(m);
586		goto drop;
587	}
588	if (in_hosteq(sc->me_src, ip->ip_src)) {
589		hlen = sizeof(struct mobhdr) - sizeof(struct in_addr);
590		mh.mob_flags = 0;
591	} else {
592		hlen = sizeof(struct mobhdr);
593		mh.mob_flags = MOB_FLAGS_SP;
594	}
595	plen = m->m_pkthdr.len;
596	ip->ip_src = sc->me_src;
597	ip->ip_dst = sc->me_dst;
598	M_SETFIB(m, sc->me_fibnum);
599	ME_RUNLOCK(sc);
600	M_PREPEND(m, hlen, M_NOWAIT);
601	if (m == NULL) {
602		error = ENOBUFS;
603		goto drop;
604	}
605	if (m->m_len < sizeof(struct ip) + hlen)
606		m = m_pullup(m, sizeof(struct ip) + hlen);
607	if (m == NULL) {
608		error = ENOBUFS;
609		goto drop;
610	}
611	memmove(mtod(m, void *), mtodo(m, hlen), sizeof(struct ip));
612	ip = mtod(m, struct ip *);
613	ip->ip_len = htons(m->m_pkthdr.len);
614	ip->ip_p = IPPROTO_MOBILE;
615	ip->ip_sum = 0;
616	mh.mob_csum = 0;
617	mh.mob_csum = me_in_cksum((uint16_t *)&mh, hlen / sizeof(uint16_t));
618	bcopy(&mh, mtodo(m, sizeof(struct ip)), hlen);
619	error = ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
620drop:
621	if (error)
622		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
623	else {
624		if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
625		if_inc_counter(ifp, IFCOUNTER_OBYTES, plen);
626	}
627	return (error);
628}
629
630static void
631me_qflush(struct ifnet *ifp __unused)
632{
633
634}
635
636static int
637memodevent(module_t mod, int type, void *data)
638{
639
640	switch (type) {
641	case MOD_LOAD:
642	case MOD_UNLOAD:
643		break;
644	default:
645		return (EOPNOTSUPP);
646	}
647	return (0);
648}
649
650static moduledata_t me_mod = {
651	"if_me",
652	memodevent,
653	0
654};
655
656DECLARE_MODULE(if_me, me_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
657MODULE_VERSION(if_me, 1);
658