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("$FreeBSD$");
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#include <net/route.h>
58
59#include <netinet/in.h>
60#include <netinet/in_systm.h>
61#include <netinet/in_var.h>
62#include <netinet/ip.h>
63#include <netinet/ip_var.h>
64#include <netinet/ip_encap.h>
65
66#include <machine/in_cksum.h>
67#include <security/mac/mac_framework.h>
68
69#define	MEMTU			1500
70static const char mename[] = "me";
71static MALLOC_DEFINE(M_IFME, mename, "Minimal Encapsulation for IP");
72static VNET_DEFINE(struct mtx, me_mtx);
73#define	V_me_mtx	VNET(me_mtx)
74/* Minimal forwarding header RFC 2004 */
75struct mobhdr {
76	uint8_t		mob_proto;	/* protocol */
77	uint8_t		mob_flags;	/* flags */
78#define	MOB_FLAGS_SP	0x80		/* source present */
79	uint16_t	mob_csum;	/* header checksum */
80	struct in_addr	mob_dst;	/* original destination address */
81	struct in_addr	mob_src;	/* original source addr (optional) */
82} __packed;
83
84struct me_softc {
85	struct ifnet		*me_ifp;
86	LIST_ENTRY(me_softc)	me_list;
87	struct rmlock		me_lock;
88	u_int			me_fibnum;
89	const struct encaptab	*me_ecookie;
90	struct in_addr		me_src;
91	struct in_addr		me_dst;
92};
93#define	ME2IFP(sc)		((sc)->me_ifp)
94#define	ME_READY(sc)		((sc)->me_src.s_addr != 0)
95#define	ME_LOCK_INIT(sc)	rm_init(&(sc)->me_lock, "me softc")
96#define	ME_LOCK_DESTROY(sc)	rm_destroy(&(sc)->me_lock)
97#define	ME_RLOCK_TRACKER	struct rm_priotracker me_tracker
98#define	ME_RLOCK(sc)		rm_rlock(&(sc)->me_lock, &me_tracker)
99#define	ME_RUNLOCK(sc)		rm_runlock(&(sc)->me_lock, &me_tracker)
100#define	ME_RLOCK_ASSERT(sc)	rm_assert(&(sc)->me_lock, RA_RLOCKED)
101#define	ME_WLOCK(sc)		rm_wlock(&(sc)->me_lock)
102#define	ME_WUNLOCK(sc)		rm_wunlock(&(sc)->me_lock)
103#define	ME_WLOCK_ASSERT(sc)	rm_assert(&(sc)->me_lock, RA_WLOCKED)
104
105#define	ME_LIST_LOCK_INIT(x)	mtx_init(&V_me_mtx, "me_mtx", NULL, MTX_DEF)
106#define	ME_LIST_LOCK_DESTROY(x)	mtx_destroy(&V_me_mtx)
107#define	ME_LIST_LOCK(x)		mtx_lock(&V_me_mtx)
108#define	ME_LIST_UNLOCK(x)	mtx_unlock(&V_me_mtx)
109
110static VNET_DEFINE(LIST_HEAD(, me_softc), me_softc_list);
111#define	V_me_softc_list	VNET(me_softc_list)
112static struct sx me_ioctl_sx;
113SX_SYSINIT(me_ioctl_sx, &me_ioctl_sx, "me_ioctl");
114
115static int	me_clone_create(struct if_clone *, int, caddr_t);
116static void	me_clone_destroy(struct ifnet *);
117static VNET_DEFINE(struct if_clone *, me_cloner);
118#define	V_me_cloner	VNET(me_cloner)
119
120static void	me_qflush(struct ifnet *);
121static int	me_transmit(struct ifnet *, struct mbuf *);
122static int	me_ioctl(struct ifnet *, u_long, caddr_t);
123static int	me_output(struct ifnet *, struct mbuf *,
124		    const struct sockaddr *, struct route *);
125static int	me_input(struct mbuf **, int *, int);
126
127static int	me_set_tunnel(struct ifnet *, struct sockaddr_in *,
128    struct sockaddr_in *);
129static void	me_delete_tunnel(struct ifnet *);
130
131SYSCTL_DECL(_net_link);
132static SYSCTL_NODE(_net_link, IFT_TUNNEL, me, CTLFLAG_RW, 0,
133    "Minimal Encapsulation for IP (RFC 2004)");
134#ifndef MAX_ME_NEST
135#define MAX_ME_NEST 1
136#endif
137
138static VNET_DEFINE(int, max_me_nesting) = MAX_ME_NEST;
139#define	V_max_me_nesting	VNET(max_me_nesting)
140SYSCTL_INT(_net_link_me, OID_AUTO, max_nesting, CTLFLAG_RW | CTLFLAG_VNET,
141    &VNET_NAME(max_me_nesting), 0, "Max nested tunnels");
142
143extern struct domain inetdomain;
144static void me_input10(struct mbuf *, int);
145static const struct protosw in_mobile_protosw = {
146	.pr_type =		SOCK_RAW,
147	.pr_domain =		&inetdomain,
148	.pr_protocol =		IPPROTO_MOBILE,
149	.pr_flags =		PR_ATOMIC|PR_ADDR,
150	.pr_input =		me_input10,
151	.pr_output =		(pr_output_t *)rip_output,
152	.pr_ctlinput =		rip_ctlinput,
153	.pr_ctloutput =		rip_ctloutput,
154	.pr_usrreqs =		&rip_usrreqs
155};
156
157static void
158vnet_me_init(const void *unused __unused)
159{
160	LIST_INIT(&V_me_softc_list);
161	ME_LIST_LOCK_INIT();
162	V_me_cloner = if_clone_simple(mename, me_clone_create,
163	    me_clone_destroy, 0);
164}
165VNET_SYSINIT(vnet_me_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
166    vnet_me_init, NULL);
167
168static void
169vnet_me_uninit(const void *unused __unused)
170{
171
172	if_clone_detach(V_me_cloner);
173	ME_LIST_LOCK_DESTROY();
174}
175VNET_SYSUNINIT(vnet_me_uninit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
176    vnet_me_uninit, NULL);
177
178static int
179me_clone_create(struct if_clone *ifc, int unit, caddr_t params)
180{
181	struct me_softc *sc;
182
183	sc = malloc(sizeof(struct me_softc), M_IFME, M_WAITOK | M_ZERO);
184	sc->me_fibnum = curthread->td_proc->p_fibnum;
185	ME2IFP(sc) = if_alloc(IFT_TUNNEL);
186	ME_LOCK_INIT(sc);
187	ME2IFP(sc)->if_softc = sc;
188	if_initname(ME2IFP(sc), mename, unit);
189
190	ME2IFP(sc)->if_mtu = MEMTU - sizeof(struct mobhdr);
191	ME2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
192	ME2IFP(sc)->if_output = me_output;
193	ME2IFP(sc)->if_ioctl = me_ioctl;
194	ME2IFP(sc)->if_transmit = me_transmit;
195	ME2IFP(sc)->if_qflush = me_qflush;
196	ME2IFP(sc)->if_capabilities |= IFCAP_LINKSTATE;
197	ME2IFP(sc)->if_capenable |= IFCAP_LINKSTATE;
198	if_attach(ME2IFP(sc));
199	bpfattach(ME2IFP(sc), DLT_NULL, sizeof(u_int32_t));
200	ME_LIST_LOCK();
201	LIST_INSERT_HEAD(&V_me_softc_list, sc, me_list);
202	ME_LIST_UNLOCK();
203	return (0);
204}
205
206static void
207me_clone_destroy(struct ifnet *ifp)
208{
209	struct me_softc *sc;
210
211	sx_xlock(&me_ioctl_sx);
212	sc = ifp->if_softc;
213	me_delete_tunnel(ifp);
214	ME_LIST_LOCK();
215	LIST_REMOVE(sc, me_list);
216	ME_LIST_UNLOCK();
217	bpfdetach(ifp);
218	if_detach(ifp);
219	ifp->if_softc = NULL;
220	sx_xunlock(&me_ioctl_sx);
221
222	if_free(ifp);
223	ME_LOCK_DESTROY(sc);
224	free(sc, M_IFME);
225}
226
227static int
228me_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
229{
230	ME_RLOCK_TRACKER;
231	struct ifreq *ifr = (struct ifreq *)data;
232	struct sockaddr_in *src, *dst;
233	struct me_softc *sc;
234	int error;
235
236	switch (cmd) {
237	case SIOCSIFMTU:
238		if (ifr->ifr_mtu < 576)
239			return (EINVAL);
240		ifp->if_mtu = ifr->ifr_mtu - sizeof(struct mobhdr);
241		return (0);
242	case SIOCSIFADDR:
243		ifp->if_flags |= IFF_UP;
244	case SIOCSIFFLAGS:
245	case SIOCADDMULTI:
246	case SIOCDELMULTI:
247		return (0);
248	}
249	sx_xlock(&me_ioctl_sx);
250	sc = ifp->if_softc;
251	if (sc == NULL) {
252		error = ENXIO;
253		goto end;
254	}
255	error = 0;
256	switch (cmd) {
257	case SIOCSIFPHYADDR:
258		src = (struct sockaddr_in *)
259			&(((struct in_aliasreq *)data)->ifra_addr);
260		dst = (struct sockaddr_in *)
261			&(((struct in_aliasreq *)data)->ifra_dstaddr);
262		if (src->sin_family != dst->sin_family ||
263		    src->sin_family != AF_INET ||
264		    src->sin_len != dst->sin_len ||
265		    src->sin_len != sizeof(struct sockaddr_in)) {
266			error = EINVAL;
267			break;
268		}
269		if (src->sin_addr.s_addr == INADDR_ANY ||
270		    dst->sin_addr.s_addr == INADDR_ANY) {
271			error = EADDRNOTAVAIL;
272			break;
273		}
274		error = me_set_tunnel(ifp, src, dst);
275		break;
276	case SIOCDIFPHYADDR:
277		me_delete_tunnel(ifp);
278		break;
279	case SIOCGIFPSRCADDR:
280	case SIOCGIFPDSTADDR:
281		ME_RLOCK(sc);
282		if (!ME_READY(sc)) {
283			error = EADDRNOTAVAIL;
284			ME_RUNLOCK(sc);
285			break;
286		}
287		src = (struct sockaddr_in *)&ifr->ifr_addr;
288		memset(src, 0, sizeof(*src));
289		src->sin_family = AF_INET;
290		src->sin_len = sizeof(*src);
291		switch (cmd) {
292		case SIOCGIFPSRCADDR:
293			src->sin_addr = sc->me_src;
294			break;
295		case SIOCGIFPDSTADDR:
296			src->sin_addr = sc->me_dst;
297			break;
298		}
299		ME_RUNLOCK(sc);
300		error = prison_if(curthread->td_ucred, sintosa(src));
301		if (error != 0)
302			memset(src, 0, sizeof(*src));
303		break;
304	case SIOCGTUNFIB:
305		ifr->ifr_fib = sc->me_fibnum;
306		break;
307	case SIOCSTUNFIB:
308		if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
309			break;
310		if (ifr->ifr_fib >= rt_numfibs)
311			error = EINVAL;
312		else
313			sc->me_fibnum = ifr->ifr_fib;
314		break;
315	default:
316		error = EINVAL;
317		break;
318	}
319end:
320	sx_xunlock(&me_ioctl_sx);
321	return (error);
322}
323
324static int
325me_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
326{
327	ME_RLOCK_TRACKER;
328	struct me_softc *sc;
329	struct ip *ip;
330	int ret;
331
332	sc = (struct me_softc *)arg;
333	if ((ME2IFP(sc)->if_flags & IFF_UP) == 0)
334		return (0);
335
336	M_ASSERTPKTHDR(m);
337
338	if (m->m_pkthdr.len < sizeof(struct ip) + sizeof(struct mobhdr) -
339	    sizeof(struct in_addr))
340		return (0);
341
342	ret = 0;
343	ME_RLOCK(sc);
344	if (ME_READY(sc)) {
345		ip = mtod(m, struct ip *);
346		if (sc->me_src.s_addr == ip->ip_dst.s_addr &&
347		    sc->me_dst.s_addr == ip->ip_src.s_addr)
348			ret = 32 * 2;
349	}
350	ME_RUNLOCK(sc);
351	return (ret);
352}
353
354static int
355me_set_tunnel(struct ifnet *ifp, struct sockaddr_in *src,
356    struct sockaddr_in *dst)
357{
358	struct me_softc *sc, *tsc;
359
360	sx_assert(&me_ioctl_sx, SA_XLOCKED);
361	ME_LIST_LOCK();
362	sc = ifp->if_softc;
363	LIST_FOREACH(tsc, &V_me_softc_list, me_list) {
364		if (tsc == sc || !ME_READY(tsc))
365			continue;
366		if (tsc->me_src.s_addr == src->sin_addr.s_addr &&
367		    tsc->me_dst.s_addr == dst->sin_addr.s_addr) {
368			ME_LIST_UNLOCK();
369			return (EADDRNOTAVAIL);
370		}
371	}
372	ME_LIST_UNLOCK();
373
374	ME_WLOCK(sc);
375	sc->me_dst = dst->sin_addr;
376	sc->me_src = src->sin_addr;
377	ME_WUNLOCK(sc);
378
379	if (sc->me_ecookie == NULL)
380		sc->me_ecookie = encap_attach_func(AF_INET, IPPROTO_MOBILE,
381		    me_encapcheck, &in_mobile_protosw, sc);
382	if (sc->me_ecookie != NULL) {
383		ifp->if_drv_flags |= IFF_DRV_RUNNING;
384		if_link_state_change(ifp, LINK_STATE_UP);
385	}
386	return (0);
387}
388
389static void
390me_delete_tunnel(struct ifnet *ifp)
391{
392	struct me_softc *sc = ifp->if_softc;
393
394	sx_assert(&me_ioctl_sx, SA_XLOCKED);
395	if (sc->me_ecookie != NULL)
396		encap_detach(sc->me_ecookie);
397	sc->me_ecookie = NULL;
398	ME_WLOCK(sc);
399	sc->me_src.s_addr = 0;
400	sc->me_dst.s_addr = 0;
401	ME_WUNLOCK(sc);
402	ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
403	if_link_state_change(ifp, LINK_STATE_DOWN);
404}
405
406static uint16_t
407me_in_cksum(uint16_t *p, int nwords)
408{
409	uint32_t sum = 0;
410
411	while (nwords-- > 0)
412		sum += *p++;
413	sum = (sum >> 16) + (sum & 0xffff);
414	sum += (sum >> 16);
415	return (~sum);
416}
417
418static void
419me_input10(struct mbuf *m, int off)
420{
421	int proto;
422
423	proto = (mtod(m, struct ip *))->ip_p;
424	me_input(&m, &off, proto);
425}
426
427int
428me_input(struct mbuf **mp, int *offp, int proto)
429{
430	struct me_softc *sc;
431	struct mobhdr *mh;
432	struct ifnet *ifp;
433	struct mbuf *m;
434	struct ip *ip;
435	int hlen;
436
437	m = *mp;
438	sc = encap_getarg(m);
439	KASSERT(sc != NULL, ("encap_getarg returned NULL"));
440
441	ifp = ME2IFP(sc);
442	/* checks for short packets */
443	hlen = sizeof(struct mobhdr);
444	if (m->m_pkthdr.len < sizeof(struct ip) + hlen)
445		hlen -= sizeof(struct in_addr);
446	if (m->m_len < sizeof(struct ip) + hlen)
447		m = m_pullup(m, sizeof(struct ip) + hlen);
448	if (m == NULL)
449		goto drop;
450	mh = (struct mobhdr *)mtodo(m, sizeof(struct ip));
451	/* check for wrong flags */
452	if (mh->mob_flags & (~MOB_FLAGS_SP)) {
453		m_freem(m);
454		goto drop;
455	}
456	if (mh->mob_flags) {
457	       if (hlen != sizeof(struct mobhdr)) {
458			m_freem(m);
459			goto drop;
460	       }
461	} else
462		hlen = sizeof(struct mobhdr) - sizeof(struct in_addr);
463	/* check mobile header checksum */
464	if (me_in_cksum((uint16_t *)mh, hlen / sizeof(uint16_t)) != 0) {
465		m_freem(m);
466		goto drop;
467	}
468#ifdef MAC
469	mac_ifnet_create_mbuf(ifp, m);
470#endif
471	ip = mtod(m, struct ip *);
472	ip->ip_dst = mh->mob_dst;
473	ip->ip_p = mh->mob_proto;
474	ip->ip_sum = 0;
475	ip->ip_len = htons(m->m_pkthdr.len - hlen);
476	if (mh->mob_flags)
477		ip->ip_src = mh->mob_src;
478	memmove(mtodo(m, hlen), ip, sizeof(struct ip));
479	m_adj(m, hlen);
480	m_clrprotoflags(m);
481	m->m_pkthdr.rcvif = ifp;
482	m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
483	M_SETFIB(m, ifp->if_fib);
484	hlen = AF_INET;
485	BPF_MTAP2(ifp, &hlen, sizeof(hlen), m);
486	if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
487	if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
488	if ((ifp->if_flags & IFF_MONITOR) != 0)
489		m_freem(m);
490	else
491		netisr_dispatch(NETISR_IP, m);
492	return (IPPROTO_DONE);
493drop:
494	if_inc_counter(ifp, IFCOUNTER_IERRORS, 1);
495	return (IPPROTO_DONE);
496}
497
498#define	MTAG_ME	1414491977
499static int
500me_check_nesting(struct ifnet *ifp, struct mbuf *m)
501{
502	struct m_tag *mtag;
503	int count;
504
505	count = 1;
506	mtag = NULL;
507	while ((mtag = m_tag_locate(m, MTAG_ME, 0, mtag)) != NULL) {
508		if (*(struct ifnet **)(mtag + 1) == ifp) {
509			log(LOG_NOTICE, "%s: loop detected\n", ifp->if_xname);
510			return (EIO);
511		}
512		count++;
513	}
514	if (count > V_max_me_nesting) {
515		log(LOG_NOTICE,
516		    "%s: if_output recursively called too many times(%d)\n",
517		    ifp->if_xname, count);
518		return (EIO);
519	}
520	mtag = m_tag_alloc(MTAG_ME, 0, sizeof(struct ifnet *), M_NOWAIT);
521	if (mtag == NULL)
522		return (ENOMEM);
523	*(struct ifnet **)(mtag + 1) = ifp;
524	m_tag_prepend(m, mtag);
525	return (0);
526}
527
528static int
529me_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
530   struct route *ro)
531{
532	uint32_t af;
533	int error;
534
535#ifdef MAC
536	error = mac_ifnet_check_transmit(ifp, m);
537	if (error != 0)
538		goto drop;
539#endif
540	if ((ifp->if_flags & IFF_MONITOR) != 0 ||
541	    (ifp->if_flags & IFF_UP) == 0) {
542		error = ENETDOWN;
543		goto drop;
544	}
545
546	error = me_check_nesting(ifp, m);
547	if (error != 0)
548		goto drop;
549
550	m->m_flags &= ~(M_BCAST|M_MCAST);
551	if (dst->sa_family == AF_UNSPEC)
552		bcopy(dst->sa_data, &af, sizeof(af));
553	else
554		af = dst->sa_family;
555	if (af != AF_INET) {
556		error = EAFNOSUPPORT;
557		goto drop;
558	}
559	BPF_MTAP2(ifp, &af, sizeof(af), m);
560	return (ifp->if_transmit(ifp, m));
561drop:
562	m_freem(m);
563	if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
564	return (error);
565}
566
567static int
568me_transmit(struct ifnet *ifp, struct mbuf *m)
569{
570	ME_RLOCK_TRACKER;
571	struct mobhdr mh;
572	struct me_softc *sc;
573	struct ip *ip;
574	int error, hlen, plen;
575
576	sc = ifp->if_softc;
577	if (sc == NULL) {
578		error = ENETDOWN;
579		m_freem(m);
580		goto drop;
581	}
582	if (m->m_len < sizeof(struct ip))
583		m = m_pullup(m, sizeof(struct ip));
584	if (m == NULL) {
585		error = ENOBUFS;
586		goto drop;
587	}
588	ip = mtod(m, struct ip *);
589	/* Fragmented datagramms shouldn't be encapsulated */
590	if (ip->ip_off & htons(IP_MF | IP_OFFMASK)) {
591		error = EINVAL;
592		m_freem(m);
593		goto drop;
594	}
595	mh.mob_proto = ip->ip_p;
596	mh.mob_src = ip->ip_src;
597	mh.mob_dst = ip->ip_dst;
598	ME_RLOCK(sc);
599	if (!ME_READY(sc)) {
600		ME_RUNLOCK(sc);
601		error = ENETDOWN;
602		m_freem(m);
603		goto drop;
604	}
605	if (in_hosteq(sc->me_src, ip->ip_src)) {
606		hlen = sizeof(struct mobhdr) - sizeof(struct in_addr);
607		mh.mob_flags = 0;
608	} else {
609		hlen = sizeof(struct mobhdr);
610		mh.mob_flags = MOB_FLAGS_SP;
611	}
612	plen = m->m_pkthdr.len;
613	ip->ip_src = sc->me_src;
614	ip->ip_dst = sc->me_dst;
615	M_SETFIB(m, sc->me_fibnum);
616	ME_RUNLOCK(sc);
617	M_PREPEND(m, hlen, M_NOWAIT);
618	if (m == NULL) {
619		error = ENOBUFS;
620		goto drop;
621	}
622	if (m->m_len < sizeof(struct ip) + hlen)
623		m = m_pullup(m, sizeof(struct ip) + hlen);
624	if (m == NULL) {
625		error = ENOBUFS;
626		goto drop;
627	}
628	memmove(mtod(m, void *), mtodo(m, hlen), sizeof(struct ip));
629	ip = mtod(m, struct ip *);
630	ip->ip_len = htons(m->m_pkthdr.len);
631	ip->ip_p = IPPROTO_MOBILE;
632	ip->ip_sum = 0;
633	mh.mob_csum = 0;
634	mh.mob_csum = me_in_cksum((uint16_t *)&mh, hlen / sizeof(uint16_t));
635	bcopy(&mh, mtodo(m, sizeof(struct ip)), hlen);
636	error = ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
637drop:
638	if (error)
639		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
640	else {
641		if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
642		if_inc_counter(ifp, IFCOUNTER_OBYTES, plen);
643	}
644	return (error);
645}
646
647static void
648me_qflush(struct ifnet *ifp __unused)
649{
650
651}
652
653static int
654memodevent(module_t mod, int type, void *data)
655{
656
657	switch (type) {
658	case MOD_LOAD:
659	case MOD_UNLOAD:
660		break;
661	default:
662		return (EOPNOTSUPP);
663	}
664	return (0);
665}
666
667static moduledata_t me_mod = {
668	"if_me",
669	memodevent,
670	0
671};
672
673DECLARE_MODULE(if_me, me_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
674MODULE_VERSION(if_me, 1);
675