xref: /freebsd/sys/net/if_me.c (revision c5fda9bac0325eb8c5b447717862d279006f318f)
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/rmlock.h>
41 #include <sys/socket.h>
42 #include <sys/sockio.h>
43 #include <sys/sx.h>
44 #include <sys/sysctl.h>
45 #include <sys/syslog.h>
46 #include <sys/systm.h>
47 
48 #include <net/bpf.h>
49 #include <net/ethernet.h>
50 #include <net/if.h>
51 #include <net/if_var.h>
52 #include <net/if_clone.h>
53 #include <net/if_types.h>
54 #include <net/netisr.h>
55 #include <net/vnet.h>
56 #include <net/route.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 - sizeof(struct mobhdr))
69 static const char mename[] = "me";
70 static MALLOC_DEFINE(M_IFME, mename, "Minimal Encapsulation for IP");
71 static VNET_DEFINE(struct mtx, me_mtx);
72 #define	V_me_mtx	VNET(me_mtx)
73 /* Minimal forwarding header RFC 2004 */
74 struct 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 
83 struct 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 
109 static VNET_DEFINE(LIST_HEAD(, me_softc), me_softc_list);
110 #define	V_me_softc_list	VNET(me_softc_list)
111 static struct sx me_ioctl_sx;
112 SX_SYSINIT(me_ioctl_sx, &me_ioctl_sx, "me_ioctl");
113 
114 static int	me_clone_create(struct if_clone *, int, caddr_t);
115 static void	me_clone_destroy(struct ifnet *);
116 static VNET_DEFINE(struct if_clone *, me_cloner);
117 #define	V_me_cloner	VNET(me_cloner)
118 
119 static void	me_qflush(struct ifnet *);
120 static int	me_transmit(struct ifnet *, struct mbuf *);
121 static int	me_ioctl(struct ifnet *, u_long, caddr_t);
122 static int	me_output(struct ifnet *, struct mbuf *,
123 		    const struct sockaddr *, struct route *);
124 static int	me_input(struct mbuf *, int, int, void *);
125 
126 static int	me_set_tunnel(struct ifnet *, struct sockaddr_in *,
127     struct sockaddr_in *);
128 static void	me_delete_tunnel(struct ifnet *);
129 static int	me_encapcheck(const struct mbuf *, int, int, void *);
130 
131 #define	ME_MINLEN	(sizeof(struct ip) + sizeof(struct mobhdr) -\
132     sizeof(in_addr_t))
133 static const struct encap_config ipv4_encap_cfg = {
134 	.proto = IPPROTO_MOBILE,
135 	.min_length = ME_MINLEN,
136 	.exact_match = (sizeof(in_addr_t) << 4) + 8,
137 	.check = me_encapcheck,
138 	.input = me_input
139 };
140 
141 SYSCTL_DECL(_net_link);
142 static SYSCTL_NODE(_net_link, IFT_TUNNEL, me, CTLFLAG_RW, 0,
143     "Minimal Encapsulation for IP (RFC 2004)");
144 #ifndef MAX_ME_NEST
145 #define MAX_ME_NEST 1
146 #endif
147 
148 static VNET_DEFINE(int, max_me_nesting) = MAX_ME_NEST;
149 #define	V_max_me_nesting	VNET(max_me_nesting)
150 SYSCTL_INT(_net_link_me, OID_AUTO, max_nesting, CTLFLAG_RW | CTLFLAG_VNET,
151     &VNET_NAME(max_me_nesting), 0, "Max nested tunnels");
152 
153 static void
154 vnet_me_init(const void *unused __unused)
155 {
156 	LIST_INIT(&V_me_softc_list);
157 	ME_LIST_LOCK_INIT();
158 	V_me_cloner = if_clone_simple(mename, me_clone_create,
159 	    me_clone_destroy, 0);
160 }
161 VNET_SYSINIT(vnet_me_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
162     vnet_me_init, NULL);
163 
164 static void
165 vnet_me_uninit(const void *unused __unused)
166 {
167 
168 	if_clone_detach(V_me_cloner);
169 	ME_LIST_LOCK_DESTROY();
170 }
171 VNET_SYSUNINIT(vnet_me_uninit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
172     vnet_me_uninit, NULL);
173 
174 static int
175 me_clone_create(struct if_clone *ifc, int unit, caddr_t params)
176 {
177 	struct me_softc *sc;
178 
179 	sc = malloc(sizeof(struct me_softc), M_IFME, M_WAITOK | M_ZERO);
180 	sc->me_fibnum = curthread->td_proc->p_fibnum;
181 	ME2IFP(sc) = if_alloc(IFT_TUNNEL);
182 	ME_LOCK_INIT(sc);
183 	ME2IFP(sc)->if_softc = sc;
184 	if_initname(ME2IFP(sc), mename, unit);
185 
186 	ME2IFP(sc)->if_mtu = MEMTU;;
187 	ME2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
188 	ME2IFP(sc)->if_output = me_output;
189 	ME2IFP(sc)->if_ioctl = me_ioctl;
190 	ME2IFP(sc)->if_transmit = me_transmit;
191 	ME2IFP(sc)->if_qflush = me_qflush;
192 	ME2IFP(sc)->if_capabilities |= IFCAP_LINKSTATE;
193 	ME2IFP(sc)->if_capenable |= IFCAP_LINKSTATE;
194 	if_attach(ME2IFP(sc));
195 	bpfattach(ME2IFP(sc), DLT_NULL, sizeof(u_int32_t));
196 	ME_LIST_LOCK();
197 	LIST_INSERT_HEAD(&V_me_softc_list, sc, me_list);
198 	ME_LIST_UNLOCK();
199 	return (0);
200 }
201 
202 static void
203 me_clone_destroy(struct ifnet *ifp)
204 {
205 	struct me_softc *sc;
206 
207 	sx_xlock(&me_ioctl_sx);
208 	sc = ifp->if_softc;
209 	me_delete_tunnel(ifp);
210 	ME_LIST_LOCK();
211 	LIST_REMOVE(sc, me_list);
212 	ME_LIST_UNLOCK();
213 	bpfdetach(ifp);
214 	if_detach(ifp);
215 	ifp->if_softc = NULL;
216 	sx_xunlock(&me_ioctl_sx);
217 
218 	if_free(ifp);
219 	ME_LOCK_DESTROY(sc);
220 	free(sc, M_IFME);
221 }
222 
223 static int
224 me_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
225 {
226 	ME_RLOCK_TRACKER;
227 	struct ifreq *ifr = (struct ifreq *)data;
228 	struct sockaddr_in *src, *dst;
229 	struct me_softc *sc;
230 	int error;
231 
232 	switch (cmd) {
233 	case SIOCSIFMTU:
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 	}
245 	sx_xlock(&me_ioctl_sx);
246 	sc = ifp->if_softc;
247 	if (sc == NULL) {
248 		error = ENXIO;
249 		goto end;
250 	}
251 	error = 0;
252 	switch (cmd) {
253 	case SIOCSIFPHYADDR:
254 		src = (struct sockaddr_in *)
255 			&(((struct in_aliasreq *)data)->ifra_addr);
256 		dst = (struct sockaddr_in *)
257 			&(((struct in_aliasreq *)data)->ifra_dstaddr);
258 		if (src->sin_family != dst->sin_family ||
259 		    src->sin_family != AF_INET ||
260 		    src->sin_len != dst->sin_len ||
261 		    src->sin_len != sizeof(struct sockaddr_in)) {
262 			error = EINVAL;
263 			break;
264 		}
265 		if (src->sin_addr.s_addr == INADDR_ANY ||
266 		    dst->sin_addr.s_addr == INADDR_ANY) {
267 			error = EADDRNOTAVAIL;
268 			break;
269 		}
270 		error = me_set_tunnel(ifp, src, dst);
271 		break;
272 	case SIOCDIFPHYADDR:
273 		me_delete_tunnel(ifp);
274 		break;
275 	case SIOCGIFPSRCADDR:
276 	case SIOCGIFPDSTADDR:
277 		ME_RLOCK(sc);
278 		if (!ME_READY(sc)) {
279 			error = EADDRNOTAVAIL;
280 			ME_RUNLOCK(sc);
281 			break;
282 		}
283 		src = (struct sockaddr_in *)&ifr->ifr_addr;
284 		memset(src, 0, sizeof(*src));
285 		src->sin_family = AF_INET;
286 		src->sin_len = sizeof(*src);
287 		switch (cmd) {
288 		case SIOCGIFPSRCADDR:
289 			src->sin_addr = sc->me_src;
290 			break;
291 		case SIOCGIFPDSTADDR:
292 			src->sin_addr = sc->me_dst;
293 			break;
294 		}
295 		ME_RUNLOCK(sc);
296 		error = prison_if(curthread->td_ucred, sintosa(src));
297 		if (error != 0)
298 			memset(src, 0, sizeof(*src));
299 		break;
300 	case SIOCGTUNFIB:
301 		ifr->ifr_fib = sc->me_fibnum;
302 		break;
303 	case SIOCSTUNFIB:
304 		if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
305 			break;
306 		if (ifr->ifr_fib >= rt_numfibs)
307 			error = EINVAL;
308 		else
309 			sc->me_fibnum = ifr->ifr_fib;
310 		break;
311 	default:
312 		error = EINVAL;
313 		break;
314 	}
315 end:
316 	sx_xunlock(&me_ioctl_sx);
317 	return (error);
318 }
319 
320 static int
321 me_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
322 {
323 	ME_RLOCK_TRACKER;
324 	struct me_softc *sc;
325 	struct ip *ip;
326 	int ret;
327 
328 	sc = (struct me_softc *)arg;
329 	if ((ME2IFP(sc)->if_flags & IFF_UP) == 0)
330 		return (0);
331 
332 	M_ASSERTPKTHDR(m);
333 
334 	ret = 0;
335 	ME_RLOCK(sc);
336 	if (ME_READY(sc)) {
337 		ip = mtod(m, struct ip *);
338 		if (sc->me_src.s_addr == ip->ip_dst.s_addr &&
339 		    sc->me_dst.s_addr == ip->ip_src.s_addr)
340 			ret = 32 * 2 + 8;
341 	}
342 	ME_RUNLOCK(sc);
343 	return (ret);
344 }
345 
346 static int
347 me_set_tunnel(struct ifnet *ifp, struct sockaddr_in *src,
348     struct sockaddr_in *dst)
349 {
350 	struct me_softc *sc, *tsc;
351 
352 	sx_assert(&me_ioctl_sx, SA_XLOCKED);
353 	ME_LIST_LOCK();
354 	sc = ifp->if_softc;
355 	LIST_FOREACH(tsc, &V_me_softc_list, me_list) {
356 		if (tsc == sc || !ME_READY(tsc))
357 			continue;
358 		if (tsc->me_src.s_addr == src->sin_addr.s_addr &&
359 		    tsc->me_dst.s_addr == dst->sin_addr.s_addr) {
360 			ME_LIST_UNLOCK();
361 			return (EADDRNOTAVAIL);
362 		}
363 	}
364 	ME_LIST_UNLOCK();
365 
366 	ME_WLOCK(sc);
367 	sc->me_dst = dst->sin_addr;
368 	sc->me_src = src->sin_addr;
369 	ME_WUNLOCK(sc);
370 
371 	if (sc->me_ecookie == NULL)
372 		sc->me_ecookie = ip_encap_attach(&ipv4_encap_cfg,
373 		    sc, M_WAITOK);
374 	if (sc->me_ecookie != NULL) {
375 		ifp->if_drv_flags |= IFF_DRV_RUNNING;
376 		if_link_state_change(ifp, LINK_STATE_UP);
377 	}
378 	return (0);
379 }
380 
381 static void
382 me_delete_tunnel(struct ifnet *ifp)
383 {
384 	struct me_softc *sc = ifp->if_softc;
385 
386 	sx_assert(&me_ioctl_sx, SA_XLOCKED);
387 	if (sc->me_ecookie != NULL)
388 		ip_encap_detach(sc->me_ecookie);
389 	sc->me_ecookie = NULL;
390 	ME_WLOCK(sc);
391 	sc->me_src.s_addr = 0;
392 	sc->me_dst.s_addr = 0;
393 	ME_WUNLOCK(sc);
394 	ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
395 	if_link_state_change(ifp, LINK_STATE_DOWN);
396 }
397 
398 static uint16_t
399 me_in_cksum(uint16_t *p, int nwords)
400 {
401 	uint32_t sum = 0;
402 
403 	while (nwords-- > 0)
404 		sum += *p++;
405 	sum = (sum >> 16) + (sum & 0xffff);
406 	sum += (sum >> 16);
407 	return (~sum);
408 }
409 
410 static int
411 me_input(struct mbuf *m, int off, int proto, void *arg)
412 {
413 	struct me_softc *sc = arg;
414 	struct mobhdr *mh;
415 	struct ifnet *ifp;
416 	struct ip *ip;
417 	int hlen;
418 
419 	ifp = ME2IFP(sc);
420 	/* checks for short packets */
421 	hlen = sizeof(struct mobhdr);
422 	if (m->m_pkthdr.len < sizeof(struct ip) + hlen)
423 		hlen -= sizeof(struct in_addr);
424 	if (m->m_len < sizeof(struct ip) + hlen)
425 		m = m_pullup(m, sizeof(struct ip) + hlen);
426 	if (m == NULL)
427 		goto drop;
428 	mh = (struct mobhdr *)mtodo(m, sizeof(struct ip));
429 	/* check for wrong flags */
430 	if (mh->mob_flags & (~MOB_FLAGS_SP)) {
431 		m_freem(m);
432 		goto drop;
433 	}
434 	if (mh->mob_flags) {
435 	       if (hlen != sizeof(struct mobhdr)) {
436 			m_freem(m);
437 			goto drop;
438 	       }
439 	} else
440 		hlen = sizeof(struct mobhdr) - sizeof(struct in_addr);
441 	/* check mobile header checksum */
442 	if (me_in_cksum((uint16_t *)mh, hlen / sizeof(uint16_t)) != 0) {
443 		m_freem(m);
444 		goto drop;
445 	}
446 #ifdef MAC
447 	mac_ifnet_create_mbuf(ifp, m);
448 #endif
449 	ip = mtod(m, struct ip *);
450 	ip->ip_dst = mh->mob_dst;
451 	ip->ip_p = mh->mob_proto;
452 	ip->ip_sum = 0;
453 	ip->ip_len = htons(m->m_pkthdr.len - hlen);
454 	if (mh->mob_flags)
455 		ip->ip_src = mh->mob_src;
456 	memmove(mtodo(m, hlen), ip, sizeof(struct ip));
457 	m_adj(m, hlen);
458 	m_clrprotoflags(m);
459 	m->m_pkthdr.rcvif = ifp;
460 	m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
461 	M_SETFIB(m, ifp->if_fib);
462 	hlen = AF_INET;
463 	BPF_MTAP2(ifp, &hlen, sizeof(hlen), m);
464 	if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
465 	if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
466 	if ((ifp->if_flags & IFF_MONITOR) != 0)
467 		m_freem(m);
468 	else
469 		netisr_dispatch(NETISR_IP, m);
470 	return (IPPROTO_DONE);
471 drop:
472 	if_inc_counter(ifp, IFCOUNTER_IERRORS, 1);
473 	return (IPPROTO_DONE);
474 }
475 
476 #define	MTAG_ME	1414491977
477 static int
478 me_check_nesting(struct ifnet *ifp, struct mbuf *m)
479 {
480 	struct m_tag *mtag;
481 	int count;
482 
483 	count = 1;
484 	mtag = NULL;
485 	while ((mtag = m_tag_locate(m, MTAG_ME, 0, mtag)) != NULL) {
486 		if (*(struct ifnet **)(mtag + 1) == ifp) {
487 			log(LOG_NOTICE, "%s: loop detected\n", ifp->if_xname);
488 			return (EIO);
489 		}
490 		count++;
491 	}
492 	if (count > V_max_me_nesting) {
493 		log(LOG_NOTICE,
494 		    "%s: if_output recursively called too many times(%d)\n",
495 		    ifp->if_xname, count);
496 		return (EIO);
497 	}
498 	mtag = m_tag_alloc(MTAG_ME, 0, sizeof(struct ifnet *), M_NOWAIT);
499 	if (mtag == NULL)
500 		return (ENOMEM);
501 	*(struct ifnet **)(mtag + 1) = ifp;
502 	m_tag_prepend(m, mtag);
503 	return (0);
504 }
505 
506 static int
507 me_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
508    struct route *ro)
509 {
510 	uint32_t af;
511 	int error;
512 
513 #ifdef MAC
514 	error = mac_ifnet_check_transmit(ifp, m);
515 	if (error != 0)
516 		goto drop;
517 #endif
518 	if ((ifp->if_flags & IFF_MONITOR) != 0 ||
519 	    (ifp->if_flags & IFF_UP) == 0) {
520 		error = ENETDOWN;
521 		goto drop;
522 	}
523 
524 	error = me_check_nesting(ifp, m);
525 	if (error != 0)
526 		goto drop;
527 
528 	m->m_flags &= ~(M_BCAST|M_MCAST);
529 	if (dst->sa_family == AF_UNSPEC)
530 		bcopy(dst->sa_data, &af, sizeof(af));
531 	else
532 		af = dst->sa_family;
533 	if (af != AF_INET) {
534 		error = EAFNOSUPPORT;
535 		goto drop;
536 	}
537 	BPF_MTAP2(ifp, &af, sizeof(af), m);
538 	return (ifp->if_transmit(ifp, m));
539 drop:
540 	m_freem(m);
541 	if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
542 	return (error);
543 }
544 
545 static int
546 me_transmit(struct ifnet *ifp, struct mbuf *m)
547 {
548 	ME_RLOCK_TRACKER;
549 	struct mobhdr mh;
550 	struct me_softc *sc;
551 	struct ip *ip;
552 	int error, hlen, plen;
553 
554 	sc = ifp->if_softc;
555 	if (sc == NULL) {
556 		error = ENETDOWN;
557 		m_freem(m);
558 		goto drop;
559 	}
560 	if (m->m_len < sizeof(struct ip))
561 		m = m_pullup(m, sizeof(struct ip));
562 	if (m == NULL) {
563 		error = ENOBUFS;
564 		goto drop;
565 	}
566 	ip = mtod(m, struct ip *);
567 	/* Fragmented datagramms shouldn't be encapsulated */
568 	if (ip->ip_off & htons(IP_MF | IP_OFFMASK)) {
569 		error = EINVAL;
570 		m_freem(m);
571 		goto drop;
572 	}
573 	mh.mob_proto = ip->ip_p;
574 	mh.mob_src = ip->ip_src;
575 	mh.mob_dst = ip->ip_dst;
576 	ME_RLOCK(sc);
577 	if (!ME_READY(sc)) {
578 		ME_RUNLOCK(sc);
579 		error = ENETDOWN;
580 		m_freem(m);
581 		goto drop;
582 	}
583 	if (in_hosteq(sc->me_src, ip->ip_src)) {
584 		hlen = sizeof(struct mobhdr) - sizeof(struct in_addr);
585 		mh.mob_flags = 0;
586 	} else {
587 		hlen = sizeof(struct mobhdr);
588 		mh.mob_flags = MOB_FLAGS_SP;
589 	}
590 	plen = m->m_pkthdr.len;
591 	ip->ip_src = sc->me_src;
592 	ip->ip_dst = sc->me_dst;
593 	M_SETFIB(m, sc->me_fibnum);
594 	ME_RUNLOCK(sc);
595 	M_PREPEND(m, hlen, M_NOWAIT);
596 	if (m == NULL) {
597 		error = ENOBUFS;
598 		goto drop;
599 	}
600 	if (m->m_len < sizeof(struct ip) + hlen)
601 		m = m_pullup(m, sizeof(struct ip) + hlen);
602 	if (m == NULL) {
603 		error = ENOBUFS;
604 		goto drop;
605 	}
606 	memmove(mtod(m, void *), mtodo(m, hlen), sizeof(struct ip));
607 	ip = mtod(m, struct ip *);
608 	ip->ip_len = htons(m->m_pkthdr.len);
609 	ip->ip_p = IPPROTO_MOBILE;
610 	ip->ip_sum = 0;
611 	mh.mob_csum = 0;
612 	mh.mob_csum = me_in_cksum((uint16_t *)&mh, hlen / sizeof(uint16_t));
613 	bcopy(&mh, mtodo(m, sizeof(struct ip)), hlen);
614 	error = ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
615 drop:
616 	if (error)
617 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
618 	else {
619 		if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
620 		if_inc_counter(ifp, IFCOUNTER_OBYTES, plen);
621 	}
622 	return (error);
623 }
624 
625 static void
626 me_qflush(struct ifnet *ifp __unused)
627 {
628 
629 }
630 
631 static int
632 memodevent(module_t mod, int type, void *data)
633 {
634 
635 	switch (type) {
636 	case MOD_LOAD:
637 	case MOD_UNLOAD:
638 		break;
639 	default:
640 		return (EOPNOTSUPP);
641 	}
642 	return (0);
643 }
644 
645 static moduledata_t me_mod = {
646 	"if_me",
647 	memodevent,
648 	0
649 };
650 
651 DECLARE_MODULE(if_me, me_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
652 MODULE_VERSION(if_me, 1);
653