xform_ipip.c revision 230442 
1/*	$FreeBSD: head/sys/netipsec/xform_ipip.c 230442 2012-01-22 02:13:19Z bz $	*/
2/*	$OpenBSD: ip_ipip.c,v 1.25 2002/06/10 18:04:55 itojun Exp $ */
3/*-
4 * The authors of this code are John Ioannidis (ji@tla.org),
5 * Angelos D. Keromytis (kermit@csd.uch.gr) and
6 * Niels Provos (provos@physnet.uni-hamburg.de).
7 *
8 * The original version of this code was written by John Ioannidis
9 * for BSD/OS in Athens, Greece, in November 1995.
10 *
11 * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
12 * by Angelos D. Keromytis.
13 *
14 * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
15 * and Niels Provos.
16 *
17 * Additional features in 1999 by Angelos D. Keromytis.
18 *
19 * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
20 * Angelos D. Keromytis and Niels Provos.
21 * Copyright (c) 2001, Angelos D. Keromytis.
22 *
23 * Permission to use, copy, and modify this software with or without fee
24 * is hereby granted, provided that this entire notice is included in
25 * all copies of any software which is or includes a copy or
26 * modification of this software.
27 * You may use this code under the GNU public license if you so wish. Please
28 * contribute changes back to the authors under this freer than GPL license
29 * so that we may further the use of strong encryption without limitations to
30 * all.
31 *
32 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
33 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
34 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
35 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
36 * PURPOSE.
37 */
38
39/*
40 * IP-inside-IP processing
41 */
42#include "opt_inet.h"
43#include "opt_inet6.h"
44#include "opt_enc.h"
45
46#include <sys/param.h>
47#include <sys/systm.h>
48#include <sys/mbuf.h>
49#include <sys/socket.h>
50#include <sys/kernel.h>
51#include <sys/protosw.h>
52#include <sys/sysctl.h>
53
54#include <net/if.h>
55#include <net/pfil.h>
56#include <net/route.h>
57#include <net/netisr.h>
58#include <net/vnet.h>
59
60#include <netinet/in.h>
61#include <netinet/in_systm.h>
62#include <netinet/in_var.h>
63#include <netinet/ip.h>
64#include <netinet/ip_ecn.h>
65#include <netinet/ip_var.h>
66#include <netinet/ip_encap.h>
67#ifdef MROUTING
68#include <netinet/ip_mroute.h>
69#endif
70
71#include <netipsec/ipsec.h>
72#include <netipsec/xform.h>
73
74#include <netipsec/ipip_var.h>
75
76#ifdef INET6
77#include <netinet/ip6.h>
78#include <netipsec/ipsec6.h>
79#include <netinet6/ip6_ecn.h>
80#include <netinet6/in6_var.h>
81#include <netinet6/ip6protosw.h>
82#endif
83
84#include <netipsec/key.h>
85#include <netipsec/key_debug.h>
86
87#include <machine/stdarg.h>
88
89/*
90 * We can control the acceptance of IP4 packets by altering the sysctl
91 * net.inet.ipip.allow value.  Zero means drop them, all else is acceptance.
92 */
93VNET_DEFINE(int, ipip_allow) = 0;
94VNET_DEFINE(struct ipipstat, ipipstat);
95
96SYSCTL_DECL(_net_inet_ipip);
97SYSCTL_VNET_INT(_net_inet_ipip, OID_AUTO,
98	ipip_allow,	CTLFLAG_RW,	&VNET_NAME(ipip_allow),	0, "");
99SYSCTL_VNET_STRUCT(_net_inet_ipip, IPSECCTL_STATS,
100	stats,		CTLFLAG_RD,	&VNET_NAME(ipipstat),	ipipstat, "");
101
102/* XXX IPCOMP */
103#define	M_IPSEC	(M_AUTHIPHDR|M_AUTHIPDGM|M_DECRYPTED)
104
105static void _ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp);
106
107#ifdef INET6
108/*
109 * Really only a wrapper for ipip_input(), for use with IPv6.
110 */
111int
112ip4_input6(struct mbuf **m, int *offp, int proto)
113{
114#if 0
115	/* If we do not accept IP-in-IP explicitly, drop.  */
116	if (!V_ipip_allow && ((*m)->m_flags & M_IPSEC) == 0) {
117		DPRINTF(("%s: dropped due to policy\n", __func__));
118		V_ipipstat.ipips_pdrops++;
119		m_freem(*m);
120		return IPPROTO_DONE;
121	}
122#endif
123	_ipip_input(*m, *offp, NULL);
124	return IPPROTO_DONE;
125}
126#endif /* INET6 */
127
128#ifdef INET
129/*
130 * Really only a wrapper for ipip_input(), for use with IPv4.
131 */
132void
133ip4_input(struct mbuf *m, int off)
134{
135#if 0
136	/* If we do not accept IP-in-IP explicitly, drop.  */
137	if (!V_ipip_allow && (m->m_flags & M_IPSEC) == 0) {
138		DPRINTF(("%s: dropped due to policy\n", __func__));
139		V_ipipstat.ipips_pdrops++;
140		m_freem(m);
141		return;
142	}
143#endif
144	_ipip_input(m, off, NULL);
145}
146#endif /* INET */
147
148/*
149 * ipip_input gets called when we receive an IP{46} encapsulated packet,
150 * either because we got it at a real interface, or because AH or ESP
151 * were being used in tunnel mode (in which case the rcvif element will
152 * contain the address of the encX interface associated with the tunnel.
153 */
154
155static void
156_ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp)
157{
158#ifdef INET
159	register struct sockaddr_in *sin;
160#endif
161	register struct ifnet *ifp;
162	register struct ifaddr *ifa;
163	struct ip *ipo;
164#ifdef INET6
165	register struct sockaddr_in6 *sin6;
166	struct ip6_hdr *ip6 = NULL;
167	u_int8_t itos;
168#endif
169	u_int8_t nxt;
170	int isr;
171	u_int8_t otos;
172	u_int8_t v;
173	int hlen;
174
175	V_ipipstat.ipips_ipackets++;
176
177	m_copydata(m, 0, 1, &v);
178
179	switch (v >> 4) {
180#ifdef INET
181        case 4:
182		hlen = sizeof(struct ip);
183		break;
184#endif /* INET */
185#ifdef INET6
186        case 6:
187		hlen = sizeof(struct ip6_hdr);
188		break;
189#endif
190        default:
191		V_ipipstat.ipips_family++;
192		m_freem(m);
193		return /* EAFNOSUPPORT */;
194	}
195
196	/* Bring the IP header in the first mbuf, if not there already */
197	if (m->m_len < hlen) {
198		if ((m = m_pullup(m, hlen)) == NULL) {
199			DPRINTF(("%s: m_pullup (1) failed\n", __func__));
200			V_ipipstat.ipips_hdrops++;
201			return;
202		}
203	}
204
205	ipo = mtod(m, struct ip *);
206
207#ifdef MROUTING
208	if (ipo->ip_v == IPVERSION && ipo->ip_p == IPPROTO_IPV4) {
209		if (IN_MULTICAST(((struct ip *)((char *) ipo + iphlen))->ip_dst.s_addr)) {
210			ipip_mroute_input (m, iphlen);
211			return;
212		}
213	}
214#endif /* MROUTING */
215
216	/* Keep outer ecn field. */
217	switch (v >> 4) {
218#ifdef INET
219	case 4:
220		otos = ipo->ip_tos;
221		break;
222#endif /* INET */
223#ifdef INET6
224	case 6:
225		otos = (ntohl(mtod(m, struct ip6_hdr *)->ip6_flow) >> 20) & 0xff;
226		break;
227#endif
228	default:
229		panic("ipip_input: unknown ip version %u (outer)", v>>4);
230	}
231
232	/* Remove outer IP header */
233	m_adj(m, iphlen);
234
235	/* Sanity check */
236	if (m->m_pkthdr.len < sizeof(struct ip))  {
237		V_ipipstat.ipips_hdrops++;
238		m_freem(m);
239		return;
240	}
241
242	m_copydata(m, 0, 1, &v);
243
244	switch (v >> 4) {
245#ifdef INET
246        case 4:
247		hlen = sizeof(struct ip);
248		break;
249#endif /* INET */
250
251#ifdef INET6
252        case 6:
253		hlen = sizeof(struct ip6_hdr);
254		break;
255#endif
256	default:
257		V_ipipstat.ipips_family++;
258		m_freem(m);
259		return; /* EAFNOSUPPORT */
260	}
261
262	/*
263	 * Bring the inner IP header in the first mbuf, if not there already.
264	 */
265	if (m->m_len < hlen) {
266		if ((m = m_pullup(m, hlen)) == NULL) {
267			DPRINTF(("%s: m_pullup (2) failed\n", __func__));
268			V_ipipstat.ipips_hdrops++;
269			return;
270		}
271	}
272
273	/*
274	 * RFC 1853 specifies that the inner TTL should not be touched on
275	 * decapsulation. There's no reason this comment should be here, but
276	 * this is as good as any a position.
277	 */
278
279	/* Some sanity checks in the inner IP header */
280	switch (v >> 4) {
281#ifdef INET
282    	case 4:
283                ipo = mtod(m, struct ip *);
284                nxt = ipo->ip_p;
285		ip_ecn_egress(V_ip4_ipsec_ecn, &otos, &ipo->ip_tos);
286                break;
287#endif /* INET */
288#ifdef INET6
289    	case 6:
290                ip6 = (struct ip6_hdr *) ipo;
291                nxt = ip6->ip6_nxt;
292		itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
293		ip_ecn_egress(V_ip6_ipsec_ecn, &otos, &itos);
294		ip6->ip6_flow &= ~htonl(0xff << 20);
295		ip6->ip6_flow |= htonl((u_int32_t) itos << 20);
296                break;
297#endif
298	default:
299		panic("ipip_input: unknown ip version %u (inner)", v>>4);
300	}
301
302	/* Check for local address spoofing. */
303	if ((m->m_pkthdr.rcvif == NULL ||
304	    !(m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK)) &&
305	    V_ipip_allow != 2) {
306	    	IFNET_RLOCK_NOSLEEP();
307		TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
308			TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
309#ifdef INET
310				if (ipo) {
311					if (ifa->ifa_addr->sa_family !=
312					    AF_INET)
313						continue;
314
315					sin = (struct sockaddr_in *) ifa->ifa_addr;
316
317					if (sin->sin_addr.s_addr ==
318					    ipo->ip_src.s_addr)	{
319						V_ipipstat.ipips_spoof++;
320						m_freem(m);
321						IFNET_RUNLOCK_NOSLEEP();
322						return;
323					}
324				}
325#endif /* INET */
326
327#ifdef INET6
328				if (ip6) {
329					if (ifa->ifa_addr->sa_family !=
330					    AF_INET6)
331						continue;
332
333					sin6 = (struct sockaddr_in6 *) ifa->ifa_addr;
334
335					if (IN6_ARE_ADDR_EQUAL(&sin6->sin6_addr, &ip6->ip6_src)) {
336						V_ipipstat.ipips_spoof++;
337						m_freem(m);
338						IFNET_RUNLOCK_NOSLEEP();
339						return;
340					}
341
342				}
343#endif /* INET6 */
344			}
345		}
346		IFNET_RUNLOCK_NOSLEEP();
347	}
348
349	/* Statistics */
350	V_ipipstat.ipips_ibytes += m->m_pkthdr.len - iphlen;
351
352#ifdef DEV_ENC
353	switch (v >> 4) {
354#ifdef INET
355	case 4:
356		ipsec_bpf(m, NULL, AF_INET, ENC_IN|ENC_AFTER);
357		break;
358#endif
359#ifdef INET6
360	case 6:
361		ipsec_bpf(m, NULL, AF_INET6, ENC_IN|ENC_AFTER);
362		break;
363#endif
364	default:
365		panic("%s: bogus ip version %u", __func__, v>>4);
366	}
367	/* pass the mbuf to enc0 for packet filtering */
368	if (ipsec_filter(&m, PFIL_IN, ENC_IN|ENC_AFTER) != 0)
369		return;
370#endif
371
372	/*
373	 * Interface pointer stays the same; if no IPsec processing has
374	 * been done (or will be done), this will point to a normal
375	 * interface. Otherwise, it'll point to an enc interface, which
376	 * will allow a packet filter to distinguish between secure and
377	 * untrusted packets.
378	 */
379
380	switch (v >> 4) {
381#ifdef INET
382	case 4:
383		isr = NETISR_IP;
384		break;
385#endif
386#ifdef INET6
387	case 6:
388		isr = NETISR_IPV6;
389		break;
390#endif
391	default:
392		panic("%s: bogus ip version %u", __func__, v>>4);
393	}
394
395	m_addr_changed(m);
396
397	if (netisr_queue(isr, m)) {	/* (0) on success. */
398		V_ipipstat.ipips_qfull++;
399		DPRINTF(("%s: packet dropped because of full queue\n",
400			__func__));
401	}
402}
403
404int
405ipip_output(
406	struct mbuf *m,
407	struct ipsecrequest *isr,
408	struct mbuf **mp,
409	int skip,
410	int protoff
411)
412{
413	struct secasvar *sav;
414	u_int8_t tp, otos;
415	struct secasindex *saidx;
416	int error;
417#if defined(INET) || defined(INET6)
418	u_int8_t itos;
419#endif
420#ifdef INET
421	struct ip *ipo;
422#endif /* INET */
423#ifdef INET6
424	struct ip6_hdr *ip6, *ip6o;
425#endif /* INET6 */
426
427	sav = isr->sav;
428	IPSEC_ASSERT(sav != NULL, ("null SA"));
429	IPSEC_ASSERT(sav->sah != NULL, ("null SAH"));
430
431	/* XXX Deal with empty TDB source/destination addresses. */
432
433	m_copydata(m, 0, 1, &tp);
434	tp = (tp >> 4) & 0xff;  /* Get the IP version number. */
435
436	saidx = &sav->sah->saidx;
437	switch (saidx->dst.sa.sa_family) {
438#ifdef INET
439	case AF_INET:
440		if (saidx->src.sa.sa_family != AF_INET ||
441		    saidx->src.sin.sin_addr.s_addr == INADDR_ANY ||
442		    saidx->dst.sin.sin_addr.s_addr == INADDR_ANY) {
443			DPRINTF(("%s: unspecified tunnel endpoint "
444			    "address in SA %s/%08lx\n", __func__,
445			    ipsec_address(&saidx->dst),
446			    (u_long) ntohl(sav->spi)));
447			V_ipipstat.ipips_unspec++;
448			error = EINVAL;
449			goto bad;
450		}
451
452		M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
453		if (m == 0) {
454			DPRINTF(("%s: M_PREPEND failed\n", __func__));
455			V_ipipstat.ipips_hdrops++;
456			error = ENOBUFS;
457			goto bad;
458		}
459
460		ipo = mtod(m, struct ip *);
461
462		ipo->ip_v = IPVERSION;
463		ipo->ip_hl = 5;
464		ipo->ip_len = htons(m->m_pkthdr.len);
465		ipo->ip_ttl = V_ip_defttl;
466		ipo->ip_sum = 0;
467		ipo->ip_src = saidx->src.sin.sin_addr;
468		ipo->ip_dst = saidx->dst.sin.sin_addr;
469
470		ipo->ip_id = ip_newid();
471
472		/* If the inner protocol is IP... */
473		switch (tp) {
474		case IPVERSION:
475			/* Save ECN notification */
476			m_copydata(m, sizeof(struct ip) +
477			    offsetof(struct ip, ip_tos),
478			    sizeof(u_int8_t), (caddr_t) &itos);
479
480			ipo->ip_p = IPPROTO_IPIP;
481
482			/*
483			 * We should be keeping tunnel soft-state and
484			 * send back ICMPs if needed.
485			 */
486			m_copydata(m, sizeof(struct ip) +
487			    offsetof(struct ip, ip_off),
488			    sizeof(u_int16_t), (caddr_t) &ipo->ip_off);
489			ipo->ip_off = ntohs(ipo->ip_off);
490			ipo->ip_off &= ~(IP_DF | IP_MF | IP_OFFMASK);
491			ipo->ip_off = htons(ipo->ip_off);
492			break;
493#ifdef INET6
494		case (IPV6_VERSION >> 4):
495		{
496			u_int32_t itos32;
497
498			/* Save ECN notification. */
499			m_copydata(m, sizeof(struct ip) +
500			    offsetof(struct ip6_hdr, ip6_flow),
501			    sizeof(u_int32_t), (caddr_t) &itos32);
502			itos = ntohl(itos32) >> 20;
503			ipo->ip_p = IPPROTO_IPV6;
504			ipo->ip_off = 0;
505			break;
506		}
507#endif /* INET6 */
508		default:
509			goto nofamily;
510		}
511
512		otos = 0;
513		ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
514		ipo->ip_tos = otos;
515		break;
516#endif /* INET */
517
518#ifdef INET6
519	case AF_INET6:
520		if (IN6_IS_ADDR_UNSPECIFIED(&saidx->dst.sin6.sin6_addr) ||
521		    saidx->src.sa.sa_family != AF_INET6 ||
522		    IN6_IS_ADDR_UNSPECIFIED(&saidx->src.sin6.sin6_addr)) {
523			DPRINTF(("%s: unspecified tunnel endpoint "
524			    "address in SA %s/%08lx\n", __func__,
525			    ipsec_address(&saidx->dst),
526			    (u_long) ntohl(sav->spi)));
527			V_ipipstat.ipips_unspec++;
528			error = ENOBUFS;
529			goto bad;
530		}
531
532		/* scoped address handling */
533		ip6 = mtod(m, struct ip6_hdr *);
534		if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
535			ip6->ip6_src.s6_addr16[1] = 0;
536		if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
537			ip6->ip6_dst.s6_addr16[1] = 0;
538
539		M_PREPEND(m, sizeof(struct ip6_hdr), M_DONTWAIT);
540		if (m == 0) {
541			DPRINTF(("%s: M_PREPEND failed\n", __func__));
542			V_ipipstat.ipips_hdrops++;
543			error = ENOBUFS;
544			goto bad;
545		}
546
547		/* Initialize IPv6 header */
548		ip6o = mtod(m, struct ip6_hdr *);
549		ip6o->ip6_flow = 0;
550		ip6o->ip6_vfc &= ~IPV6_VERSION_MASK;
551		ip6o->ip6_vfc |= IPV6_VERSION;
552		ip6o->ip6_plen = htons(m->m_pkthdr.len);
553		ip6o->ip6_hlim = V_ip_defttl;
554		ip6o->ip6_dst = saidx->dst.sin6.sin6_addr;
555		ip6o->ip6_src = saidx->src.sin6.sin6_addr;
556
557		switch (tp) {
558#ifdef INET
559		case IPVERSION:
560			/* Save ECN notification */
561			m_copydata(m, sizeof(struct ip6_hdr) +
562			    offsetof(struct ip, ip_tos), sizeof(u_int8_t),
563			    (caddr_t) &itos);
564
565			/* This is really IPVERSION. */
566			ip6o->ip6_nxt = IPPROTO_IPIP;
567			break;
568#endif /* INET */
569		case (IPV6_VERSION >> 4):
570		{
571			u_int32_t itos32;
572
573			/* Save ECN notification. */
574			m_copydata(m, sizeof(struct ip6_hdr) +
575			    offsetof(struct ip6_hdr, ip6_flow),
576			    sizeof(u_int32_t), (caddr_t) &itos32);
577			itos = ntohl(itos32) >> 20;
578
579			ip6o->ip6_nxt = IPPROTO_IPV6;
580		}
581		default:
582			goto nofamily;
583		}
584
585		otos = 0;
586		ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
587		ip6o->ip6_flow |= htonl((u_int32_t) otos << 20);
588		break;
589#endif /* INET6 */
590
591	default:
592nofamily:
593		DPRINTF(("%s: unsupported protocol family %u\n", __func__,
594		    saidx->dst.sa.sa_family));
595		V_ipipstat.ipips_family++;
596		error = EAFNOSUPPORT;		/* XXX diffs from openbsd */
597		goto bad;
598	}
599
600	V_ipipstat.ipips_opackets++;
601	*mp = m;
602
603#ifdef INET
604	if (saidx->dst.sa.sa_family == AF_INET) {
605#if 0
606		if (sav->tdb_xform->xf_type == XF_IP4)
607			tdb->tdb_cur_bytes +=
608			    m->m_pkthdr.len - sizeof(struct ip);
609#endif
610		V_ipipstat.ipips_obytes += m->m_pkthdr.len - sizeof(struct ip);
611	}
612#endif /* INET */
613
614#ifdef INET6
615	if (saidx->dst.sa.sa_family == AF_INET6) {
616#if 0
617		if (sav->tdb_xform->xf_type == XF_IP4)
618			tdb->tdb_cur_bytes +=
619			    m->m_pkthdr.len - sizeof(struct ip6_hdr);
620#endif
621		V_ipipstat.ipips_obytes +=
622		    m->m_pkthdr.len - sizeof(struct ip6_hdr);
623	}
624#endif /* INET6 */
625
626	return 0;
627bad:
628	if (m)
629		m_freem(m);
630	*mp = NULL;
631	return (error);
632}
633
634#ifdef IPSEC
635#if defined(INET) || defined(INET6)
636static int
637ipe4_init(struct secasvar *sav, struct xformsw *xsp)
638{
639	sav->tdb_xform = xsp;
640	return 0;
641}
642
643static int
644ipe4_zeroize(struct secasvar *sav)
645{
646	sav->tdb_xform = NULL;
647	return 0;
648}
649
650static int
651ipe4_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
652{
653	/* This is a rather serious mistake, so no conditional printing. */
654	printf("%s: should never be called\n", __func__);
655	if (m)
656		m_freem(m);
657	return EOPNOTSUPP;
658}
659
660static struct xformsw ipe4_xformsw = {
661	XF_IP4,		0,		"IPv4 Simple Encapsulation",
662	ipe4_init,	ipe4_zeroize,	ipe4_input,	ipip_output,
663};
664
665extern struct domain inetdomain;
666#endif /* INET || INET6 */
667#ifdef INET
668static struct protosw ipe4_protosw = {
669	.pr_type =	SOCK_RAW,
670	.pr_domain =	&inetdomain,
671	.pr_protocol =	IPPROTO_IPV4,
672	.pr_flags =	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
673	.pr_input =	ip4_input,
674	.pr_ctloutput =	rip_ctloutput,
675	.pr_usrreqs =	&rip_usrreqs
676};
677#endif /* INET */
678#if defined(INET6) && defined(INET)
679static struct ip6protosw ipe6_protosw = {
680	.pr_type =	SOCK_RAW,
681	.pr_domain =	&inetdomain,
682	.pr_protocol =	IPPROTO_IPV6,
683	.pr_flags =	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
684	.pr_input =	ip4_input6,
685	.pr_ctloutput =	rip_ctloutput,
686	.pr_usrreqs =	&rip_usrreqs
687};
688#endif /* INET6 && INET */
689
690#ifdef INET
691/*
692 * Check the encapsulated packet to see if we want it
693 */
694static int
695ipe4_encapcheck(const struct mbuf *m, int off, int proto, void *arg)
696{
697	/*
698	 * Only take packets coming from IPSEC tunnels; the rest
699	 * must be handled by the gif tunnel code.  Note that we
700	 * also return a minimum priority when we want the packet
701	 * so any explicit gif tunnels take precedence.
702	 */
703	return ((m->m_flags & M_IPSEC) != 0 ? 1 : 0);
704}
705#endif /* INET */
706
707static void
708ipe4_attach(void)
709{
710
711	xform_register(&ipe4_xformsw);
712	/* attach to encapsulation framework */
713	/* XXX save return cookie for detach on module remove */
714#ifdef INET
715	(void) encap_attach_func(AF_INET, -1,
716		ipe4_encapcheck, &ipe4_protosw, NULL);
717#endif
718#if defined(INET6) && defined(INET)
719	(void) encap_attach_func(AF_INET6, -1,
720		ipe4_encapcheck, (struct protosw *)&ipe6_protosw, NULL);
721#endif
722}
723SYSINIT(ipe4_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, ipe4_attach, NULL);
724#endif	/* IPSEC */
725