xref: /netbsd-src/sys/netipsec/xform_ipip.c (revision e89934bbf778a6d6d6894877c4da59d0c7835b0f)
1 /*	$NetBSD: xform_ipip.c,v 1.42 2016/07/07 09:32:03 ozaki-r Exp $	*/
2 /*	$FreeBSD: src/sys/netipsec/xform_ipip.c,v 1.3.2.1 2003/01/24 05:11:36 sam Exp $	*/
3 /*	$OpenBSD: ip_ipip.c,v 1.25 2002/06/10 18:04:55 itojun Exp $ */
4 
5 /*
6  * The authors of this code are John Ioannidis (ji@tla.org),
7  * Angelos D. Keromytis (kermit@csd.uch.gr) and
8  * Niels Provos (provos@physnet.uni-hamburg.de).
9  *
10  * The original version of this code was written by John Ioannidis
11  * for BSD/OS in Athens, Greece, in November 1995.
12  *
13  * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
14  * by Angelos D. Keromytis.
15  *
16  * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
17  * and Niels Provos.
18  *
19  * Additional features in 1999 by Angelos D. Keromytis.
20  *
21  * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
22  * Angelos D. Keromytis and Niels Provos.
23  * Copyright (c) 2001, Angelos D. Keromytis.
24  *
25  * Permission to use, copy, and modify this software with or without fee
26  * is hereby granted, provided that this entire notice is included in
27  * all copies of any software which is or includes a copy or
28  * modification of this software.
29  * You may use this code under the GNU public license if you so wish. Please
30  * contribute changes back to the authors under this freer than GPL license
31  * so that we may further the use of strong encryption without limitations to
32  * all.
33  *
34  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
35  * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
36  * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
37  * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
38  * PURPOSE.
39  */
40 
41 #include <sys/cdefs.h>
42 __KERNEL_RCSID(0, "$NetBSD: xform_ipip.c,v 1.42 2016/07/07 09:32:03 ozaki-r Exp $");
43 
44 /*
45  * IP-inside-IP processing
46  */
47 #include "opt_inet.h"
48 #ifdef __FreeBSD__
49 #include "opt_inet6.h"
50 #include "opt_random_ip_id.h"
51 #endif /* __FreeBSD__ */
52 
53 
54 #include <sys/param.h>
55 #include <sys/systm.h>
56 #include <sys/mbuf.h>
57 #include <sys/socket.h>
58 #include <sys/kernel.h>
59 #include <sys/protosw.h>
60 #include <sys/sysctl.h>
61 
62 #include <net/if.h>
63 #include <net/route.h>
64 #include <net/netisr.h>
65 
66 #include <netinet/in.h>
67 #include <netinet/in_systm.h>
68 #include <netinet/in_var.h>
69 #include <netinet/ip.h>
70 #include <netinet/ip_ecn.h>
71 #include <netinet/ip_var.h>
72 #include <netinet/ip_encap.h>
73 #ifdef __FreeBSD__
74 #include <netinet/ipprotosw.h>
75 #endif
76 
77 #include <netipsec/ipsec.h>
78 #include <netipsec/ipsec_private.h>
79 #include <netipsec/xform.h>
80 
81 #include <netipsec/ipip_var.h>
82 
83 #ifdef MROUTING
84 #include <netinet/ip_mroute.h>
85 #endif
86 
87 #ifdef INET6
88 #include <netinet/ip6.h>
89 #include <netipsec/ipsec6.h>
90 #  ifdef __FreeBSD__
91 #  include <netinet6/ip6_ecn.h>
92 #  endif
93 #include <netinet6/in6_var.h>
94 #include <netinet6/ip6protosw.h>
95 #endif
96 
97 #include <netipsec/key.h>
98 #include <netipsec/key_debug.h>
99 #include <netipsec/ipsec_osdep.h>
100 
101 #ifdef __FreeBSD__
102 typedef void	pr_in_input_t (struct mbuf *, int, int); /* XXX FIX THIS */
103 #else
104 typedef void	pr_in_input_t (struct mbuf *m, ...);
105 #endif
106 
107 /*
108  * We can control the acceptance of IP4 packets by altering the sysctl
109  * net.inet.ipip.allow value.  Zero means drop them, all else is acceptance.
110  */
111 int	ipip_allow = 0;
112 
113 percpu_t *ipipstat_percpu;
114 
115 #ifdef SYSCTL_DECL
116 SYSCTL_DECL(_net_inet_ipip);
117 
118 SYSCTL_INT(_net_inet_ipip, OID_AUTO,
119 	ipip_allow,	CTLFLAG_RW,	&ipip_allow,	0, "");
120 SYSCTL_STRUCT(_net_inet_ipip, IPSECCTL_STATS,
121 	stats,		CTLFLAG_RD,	&ipipstat,	ipipstat, "");
122 
123 #endif
124 
125 #ifdef __FreeBSD__
126 static
127 #endif
128 void ipe4_attach(void);
129 
130 
131 /* XXX IPCOMP */
132 #define	M_IPSEC	(M_AUTHIPHDR|M_AUTHIPDGM|M_DECRYPTED)
133 
134 static void _ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp);
135 
136 #ifdef INET6
137 /*
138  * Really only a wrapper for ipip_input(), for use with IPv6.
139  */
140 int
141 ip4_input6(struct mbuf **m, int *offp, int proto)
142 {
143 #if 0
144 	/* If we do not accept IP-in-IP explicitly, drop.  */
145 	if (!ipip_allow && ((*m)->m_flags & M_IPSEC) == 0) {
146 		DPRINTF(("ip4_input6: dropped due to policy\n"));
147 		IPIP_STATINC(IPIP_STAT_PDROPS);
148 		m_freem(*m);
149 		return IPPROTO_DONE;
150 	}
151 #endif
152 	_ipip_input(*m, *offp, NULL);
153 	return IPPROTO_DONE;
154 }
155 #endif /* INET6 */
156 
157 #ifdef INET
158 /*
159  * Really only a wrapper for ipip_input(), for use with IPv4.
160  */
161 void
162 ip4_input(struct mbuf *m, int off, int proto)
163 {
164 
165 #if 0
166 	/* If we do not accept IP-in-IP explicitly, drop.  */
167 	if (!ipip_allow && (m->m_flags & M_IPSEC) == 0) {
168 		DPRINTF(("ip4_input: dropped due to policy\n"));
169 		IPIP_STATINC(IPIP_STAT_PDROPS);
170 		m_freem(m);
171 		return;
172 	}
173 #endif
174 
175 	_ipip_input(m, off, NULL);
176 }
177 #endif /* INET */
178 
179 /*
180  * ipip_input gets called when we receive an IP{46} encapsulated packet,
181  * either because we got it at a real interface, or because AH or ESP
182  * were being used in tunnel mode (in which case the rcvif element will
183  * contain the address of the encX interface associated with the tunnel.
184  */
185 
186 static void
187 _ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp)
188 {
189 	register struct sockaddr_in *sin;
190 	register struct ifnet *ifp;
191 	register struct ifaddr *ifa;
192 	pktqueue_t *pktq = NULL;
193 	struct ip *ipo;
194 #ifdef INET6
195 	register struct sockaddr_in6 *sin6;
196 	struct ip6_hdr *ip6 = NULL;
197 	u_int8_t itos;
198 #endif
199 	u_int8_t otos;
200 	u_int8_t v;
201 	int hlen;
202 
203 	IPIP_STATINC(IPIP_STAT_IPACKETS);
204 
205 	m_copydata(m, 0, 1, &v);
206 
207 	switch (v >> 4) {
208 #ifdef INET
209         case 4:
210 		hlen = sizeof(struct ip);
211 		break;
212 #endif /* INET */
213 #ifdef INET6
214         case 6:
215 		hlen = sizeof(struct ip6_hdr);
216 		break;
217 #endif
218         default:
219 		DPRINTF(("_ipip_input: bad protocol version 0x%x (%u) "
220 			"for outer header\n", v, v>>4));
221 		IPIP_STATINC(IPIP_STAT_FAMILY);
222 		m_freem(m);
223 		return /* EAFNOSUPPORT */;
224 	}
225 
226 	/* Bring the IP header in the first mbuf, if not there already */
227 	if (m->m_len < hlen) {
228 		if ((m = m_pullup(m, hlen)) == NULL) {
229 			DPRINTF(("ipip_input: m_pullup (1) failed\n"));
230 			IPIP_STATINC(IPIP_STAT_HDROPS);
231 			return;
232 		}
233 	}
234 
235 	ipo = mtod(m, struct ip *);
236 
237 #ifdef MROUTING
238 	if (ipo->ip_v == IPVERSION && ipo->ip_p == IPPROTO_IPV4) {
239 		if (IN_MULTICAST(((struct ip *)((char *) ipo + iphlen))->ip_dst.s_addr)) {
240 			ipip_mroute_input (m, iphlen);
241 			return;
242 		}
243 	}
244 #endif /* MROUTING */
245 
246 	/* Keep outer ecn field. */
247 	switch (v >> 4) {
248 #ifdef INET
249 	case 4:
250 		otos = ipo->ip_tos;
251 		break;
252 #endif /* INET */
253 #ifdef INET6
254 	case 6:
255 		otos = (ntohl(mtod(m, struct ip6_hdr *)->ip6_flow) >> 20) & 0xff;
256 		break;
257 #endif
258 	default:
259 		panic("ipip_input: unknown ip version %u (outer)", v>>4);
260 	}
261 
262 	/* Remove outer IP header */
263 	m_adj(m, iphlen);
264 
265 	/* Sanity check */
266 	if (m->m_pkthdr.len < sizeof(struct ip))  {
267 		IPIP_STATINC(IPIP_STAT_HDROPS);
268 		m_freem(m);
269 		return;
270 	}
271 
272 	m_copydata(m, 0, 1, &v);
273 
274 	switch (v >> 4) {
275 #ifdef INET
276         case 4:
277 		hlen = sizeof(struct ip);
278 		break;
279 #endif /* INET */
280 
281 #ifdef INET6
282         case 6:
283 		hlen = sizeof(struct ip6_hdr);
284 		break;
285 #endif
286 	default:
287 		DPRINTF(("_ipip_input: bad protocol version 0x%x (%u) "
288 			"for inner header\n", v, v>>4));
289 		IPIP_STATINC(IPIP_STAT_FAMILY);
290 		m_freem(m);
291 		return; /* EAFNOSUPPORT */
292 	}
293 
294 	/*
295 	 * Bring the inner IP header in the first mbuf, if not there already.
296 	 */
297 	if (m->m_len < hlen) {
298 		if ((m = m_pullup(m, hlen)) == NULL) {
299 			DPRINTF(("ipip_input: m_pullup (2) failed\n"));
300 			IPIP_STATINC(IPIP_STAT_HDROPS);
301 			return;
302 		}
303 	}
304 
305 	/*
306 	 * RFC 1853 specifies that the inner TTL should not be touched on
307 	 * decapsulation. There's no reason this comment should be here, but
308 	 * this is as good as any a position.
309 	 */
310 
311 	/* Some sanity checks in the inner IP header */
312 	switch (v >> 4) {
313 #ifdef INET
314     	case 4:
315                 ipo = mtod(m, struct ip *);
316 		ip_ecn_egress(ip4_ipsec_ecn, &otos, &ipo->ip_tos);
317                 break;
318 #endif /* INET */
319 #ifdef INET6
320     	case 6:
321                 ip6 = (struct ip6_hdr *) ipo;
322 		itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
323 		ip_ecn_egress(ip6_ipsec_ecn, &otos, &itos);
324 		ip6->ip6_flow &= ~htonl(0xff << 20);
325 		ip6->ip6_flow |= htonl((u_int32_t) itos << 20);
326                 break;
327 #endif
328 	default:
329 		panic("ipip_input: unknown ip version %u (inner)", v>>4);
330 	}
331 
332 	/* Check for local address spoofing. */
333 	if ((m_get_rcvif_NOMPSAFE(m) == NULL ||
334 	    !(m_get_rcvif_NOMPSAFE(m)->if_flags & IFF_LOOPBACK)) &&
335 	    ipip_allow != 2) {
336 		int s = pserialize_read_enter();
337 		IFNET_READER_FOREACH(ifp) {
338 			IFADDR_READER_FOREACH(ifa, ifp) {
339 #ifdef INET
340 				if (ipo) {
341 					if (ifa->ifa_addr->sa_family !=
342 					    AF_INET)
343 						continue;
344 
345 					sin = (struct sockaddr_in *) ifa->ifa_addr;
346 
347 					if (sin->sin_addr.s_addr ==
348 					    ipo->ip_src.s_addr)	{
349 						pserialize_read_exit(s);
350 						IPIP_STATINC(IPIP_STAT_SPOOF);
351 						m_freem(m);
352 						return;
353 					}
354 				}
355 #endif /* INET */
356 
357 #ifdef INET6
358 				if (ip6) {
359 					if (ifa->ifa_addr->sa_family !=
360 					    AF_INET6)
361 						continue;
362 
363 					sin6 = (struct sockaddr_in6 *) ifa->ifa_addr;
364 
365 					if (IN6_ARE_ADDR_EQUAL(&sin6->sin6_addr, &ip6->ip6_src)) {
366 						pserialize_read_exit(s);
367 						IPIP_STATINC(IPIP_STAT_SPOOF);
368 						m_freem(m);
369 						return;
370 					}
371 
372 				}
373 #endif /* INET6 */
374 			}
375 		}
376 		pserialize_read_exit(s);
377 	}
378 
379 	/* Statistics */
380 	IPIP_STATADD(IPIP_STAT_IBYTES, m->m_pkthdr.len - iphlen);
381 
382 	/*
383 	 * Interface pointer stays the same; if no IPsec processing has
384 	 * been done (or will be done), this will point to a normal
385 	 * interface. Otherwise, it'll point to an enc interface, which
386 	 * will allow a packet filter to distinguish between secure and
387 	 * untrusted packets.
388 	 */
389 
390 	switch (v >> 4) {
391 #ifdef INET
392 	case 4:
393 		pktq = ip_pktq;
394 		break;
395 #endif
396 #ifdef INET6
397 	case 6:
398 		pktq = ip6_pktq;
399 		break;
400 #endif
401 	default:
402 		panic("ipip_input: should never reach here");
403 	}
404 
405 	int s = splnet();
406 	if (__predict_false(!pktq_enqueue(pktq, m, 0))) {
407 		IPIP_STATINC(IPIP_STAT_QFULL);
408 		m_freem(m);
409 	}
410 	splx(s);
411 }
412 
413 int
414 ipip_output(
415     struct mbuf *m,
416     struct ipsecrequest *isr,
417     struct mbuf **mp,
418     int skip,
419     int protoff
420 )
421 {
422 	const struct secasvar *sav;
423 	u_int8_t tp, otos;
424 	struct secasindex *saidx;
425 	int error;
426 #ifdef INET
427 	u_int8_t itos;
428 	struct ip *ipo;
429 #endif /* INET */
430 #ifdef INET6
431 	struct ip6_hdr *ip6, *ip6o;
432 #endif /* INET6 */
433 
434 	IPSEC_SPLASSERT_SOFTNET("ipip_output");
435 
436 	sav = isr->sav;
437 	IPSEC_ASSERT(sav != NULL, ("ipip_output: null SA"));
438 	IPSEC_ASSERT(sav->sah != NULL, ("ipip_output: null SAH"));
439 
440 	/* XXX Deal with empty TDB source/destination addresses. */
441 
442 	m_copydata(m, 0, 1, &tp);
443 	tp = (tp >> 4) & 0xff;  /* Get the IP version number. */
444 
445 	saidx = &sav->sah->saidx;
446 	switch (saidx->dst.sa.sa_family) {
447 #ifdef INET
448 	case AF_INET:
449 		if (saidx->src.sa.sa_family != AF_INET ||
450 		    saidx->src.sin.sin_addr.s_addr == INADDR_ANY ||
451 		    saidx->dst.sin.sin_addr.s_addr == INADDR_ANY) {
452 			DPRINTF(("ipip_output: unspecified tunnel endpoint "
453 			    "address in SA %s/%08lx\n",
454 			    ipsec_address(&saidx->dst),
455 			    (u_long) ntohl(sav->spi)));
456 			IPIP_STATINC(IPIP_STAT_UNSPEC);
457 			error = EINVAL;
458 			goto bad;
459 		}
460 
461 		M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
462 		if (m == 0) {
463 			DPRINTF(("ipip_output: M_PREPEND failed\n"));
464 			IPIP_STATINC(IPIP_STAT_HDROPS);
465 			error = ENOBUFS;
466 			goto bad;
467 		}
468 
469 		ipo = mtod(m, struct ip *);
470 
471 		ipo->ip_v = IPVERSION;
472 		ipo->ip_hl = 5;
473 		ipo->ip_len = htons(m->m_pkthdr.len);
474 		ipo->ip_ttl = ip_defttl;
475 		ipo->ip_sum = 0;
476 		ipo->ip_src = saidx->src.sin.sin_addr;
477 		ipo->ip_dst = saidx->dst.sin.sin_addr;
478 
479 #if defined(__NetBSD__)
480 		ipo->ip_id = ip_newid(NULL);
481 #elif defined(RANDOM_IP_ID)
482 		ipo->ip_id = ip_randomid();
483 #else
484 		ipo->ip_id = htons(ip_id++);
485 #endif
486 
487 		/* If the inner protocol is IP... */
488 		if (tp == IPVERSION) {
489 			/* Save ECN notification */
490 			m_copydata(m, sizeof(struct ip) +
491 			    offsetof(struct ip, ip_tos),
492 			    sizeof(u_int8_t), &itos);
493 
494 			ipo->ip_p = IPPROTO_IPIP;
495 
496 			/*
497 			 * We should be keeping tunnel soft-state and
498 			 * send back ICMPs if needed.
499 			 */
500 			m_copydata(m, sizeof(struct ip) +
501 			    offsetof(struct ip, ip_off),
502 			    sizeof(u_int16_t), &ipo->ip_off);
503 			ipo->ip_off &= ~ IP_OFF_CONVERT(IP_DF | IP_MF | IP_OFFMASK);
504 		}
505 #ifdef INET6
506 		else if (tp == (IPV6_VERSION >> 4)) {
507 			u_int32_t itos32;
508 
509 			/* Save ECN notification. */
510 			m_copydata(m, sizeof(struct ip) +
511 			    offsetof(struct ip6_hdr, ip6_flow),
512 			    sizeof(u_int32_t), &itos32);
513 			itos = ntohl(itos32) >> 20;
514 			ipo->ip_p = IPPROTO_IPV6;
515 			ipo->ip_off = 0;
516 		}
517 #endif /* INET6 */
518 		else {
519 			goto nofamily;
520 		}
521 
522 		otos = 0;
523 		ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
524 		ipo->ip_tos = otos;
525 		break;
526 #endif /* INET */
527 
528 #ifdef INET6
529 	case AF_INET6:
530 		if (IN6_IS_ADDR_UNSPECIFIED(&saidx->dst.sin6.sin6_addr) ||
531 		    saidx->src.sa.sa_family != AF_INET6 ||
532 		    IN6_IS_ADDR_UNSPECIFIED(&saidx->src.sin6.sin6_addr)) {
533 			DPRINTF(("ipip_output: unspecified tunnel endpoint "
534 			    "address in SA %s/%08lx\n",
535 			    ipsec_address(&saidx->dst),
536 			    (u_long) ntohl(sav->spi)));
537 			IPIP_STATINC(IPIP_STAT_UNSPEC);
538 			error = ENOBUFS;
539 			goto bad;
540 		}
541 
542 		if (tp == (IPV6_VERSION >> 4)) {
543 			/* scoped address handling */
544 			ip6 = mtod(m, struct ip6_hdr *);
545 			if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
546 				ip6->ip6_src.s6_addr16[1] = 0;
547 			if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
548 				ip6->ip6_dst.s6_addr16[1] = 0;
549 		}
550 
551 		M_PREPEND(m, sizeof(struct ip6_hdr), M_DONTWAIT);
552 		if (m == 0) {
553 			DPRINTF(("ipip_output: M_PREPEND failed\n"));
554 			IPIP_STATINC(IPIP_STAT_HDROPS);
555 			error = ENOBUFS;
556 			goto bad;
557 		}
558 
559 		/* Initialize IPv6 header */
560 		ip6o = mtod(m, struct ip6_hdr *);
561 		ip6o->ip6_flow = 0;
562 		ip6o->ip6_vfc &= ~IPV6_VERSION_MASK;
563 		ip6o->ip6_vfc |= IPV6_VERSION;
564 		ip6o->ip6_plen = htons(m->m_pkthdr.len);
565 		ip6o->ip6_hlim = ip_defttl;
566 		ip6o->ip6_dst = saidx->dst.sin6.sin6_addr;
567 		ip6o->ip6_src = saidx->src.sin6.sin6_addr;
568 		if (IN6_IS_SCOPE_LINKLOCAL(&ip6o->ip6_dst))
569 			ip6o->ip6_dst.s6_addr16[1] = htons(saidx->dst.sin6.sin6_scope_id);
570 		if (IN6_IS_SCOPE_LINKLOCAL(&ip6o->ip6_src))
571 			ip6o->ip6_src.s6_addr16[1] = htons(saidx->src.sin6.sin6_scope_id);
572 
573 #ifdef INET
574 		if (tp == IPVERSION) {
575 			/* Save ECN notification */
576 			m_copydata(m, sizeof(struct ip6_hdr) +
577 			    offsetof(struct ip, ip_tos), sizeof(u_int8_t),
578 			    &itos);
579 
580 			/* This is really IPVERSION. */
581 			ip6o->ip6_nxt = IPPROTO_IPIP;
582 		} else
583 #endif /* INET */
584 			if (tp == (IPV6_VERSION >> 4)) {
585 				u_int32_t itos32;
586 
587 				/* Save ECN notification. */
588 				m_copydata(m, sizeof(struct ip6_hdr) +
589 				    offsetof(struct ip6_hdr, ip6_flow),
590 				    sizeof(u_int32_t), &itos32);
591 				itos = ntohl(itos32) >> 20;
592 
593 				ip6o->ip6_nxt = IPPROTO_IPV6;
594 			} else {
595 				goto nofamily;
596 			}
597 
598 		otos = 0;
599 		ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
600 		ip6o->ip6_flow |= htonl((u_int32_t) otos << 20);
601 		break;
602 #endif /* INET6 */
603 
604 	default:
605 nofamily:
606 		DPRINTF(("ipip_output: unsupported protocol family %u\n",
607 		    saidx->dst.sa.sa_family));
608 		IPIP_STATINC(IPIP_STAT_FAMILY);
609 		error = EAFNOSUPPORT;		/* XXX diffs from openbsd */
610 		goto bad;
611 	}
612 
613 	IPIP_STATINC(IPIP_STAT_OPACKETS);
614 	*mp = m;
615 
616 #ifdef INET
617 	if (saidx->dst.sa.sa_family == AF_INET) {
618 #if 0
619 		if (sav->tdb_xform->xf_type == XF_IP4)
620 			tdb->tdb_cur_bytes +=
621 			    m->m_pkthdr.len - sizeof(struct ip);
622 #endif
623 		IPIP_STATADD(IPIP_STAT_OBYTES,
624 			     m->m_pkthdr.len - sizeof(struct ip));
625 	}
626 #endif /* INET */
627 
628 #ifdef INET6
629 	if (saidx->dst.sa.sa_family == AF_INET6) {
630 #if 0
631 		if (sav->tdb_xform->xf_type == XF_IP4)
632 			tdb->tdb_cur_bytes +=
633 			    m->m_pkthdr.len - sizeof(struct ip6_hdr);
634 #endif
635 		IPIP_STATADD(IPIP_STAT_OBYTES,
636 		    m->m_pkthdr.len - sizeof(struct ip6_hdr));
637 	}
638 #endif /* INET6 */
639 
640 	return 0;
641 bad:
642 	if (m)
643 		m_freem(m);
644 	*mp = NULL;
645 	return (error);
646 }
647 
648 static int
649 ipe4_init(struct secasvar *sav, const struct xformsw *xsp)
650 {
651 	sav->tdb_xform = xsp;
652 	return 0;
653 }
654 
655 static int
656 ipe4_zeroize(struct secasvar *sav)
657 {
658 	sav->tdb_xform = NULL;
659 	return 0;
660 }
661 
662 static int
663 ipe4_input(
664     struct mbuf *m,
665     const struct secasvar *sav,
666     int skip,
667     int protoff
668 )
669 {
670 	/* This is a rather serious mistake, so no conditional printing. */
671 	printf("ipe4_input: should never be called\n");
672 	if (m)
673 		m_freem(m);
674 	return EOPNOTSUPP;
675 }
676 
677 static struct xformsw ipe4_xformsw = {
678 	XF_IP4,		0,		"IPv4 Simple Encapsulation",
679 	ipe4_init,	ipe4_zeroize,	ipe4_input,	ipip_output,
680 	NULL,
681 };
682 
683 #ifdef INET
684 static struct encapsw ipe4_encapsw = {
685 	.encapsw4 = {
686 		.pr_input = ip4_input,
687 		.pr_ctlinput = NULL,
688 	}
689 };
690 #endif
691 #ifdef INET6
692 static struct encapsw ipe4_encapsw6 = {
693 	.encapsw6 = {
694 		.pr_input = ip4_input6,
695 		.pr_ctlinput = NULL,
696 	}
697 };
698 #endif
699 
700 /*
701  * Check the encapsulated packet to see if we want it
702  */
703 static int
704 ipe4_encapcheck(struct mbuf *m,
705     int off,
706     int proto,
707     void *arg
708 )
709 {
710 	/*
711 	 * Only take packets coming from IPSEC tunnels; the rest
712 	 * must be handled by the gif tunnel code.  Note that we
713 	 * also return a minimum priority when we want the packet
714 	 * so any explicit gif tunnels take precedence.
715 	 */
716 	return ((m->m_flags & M_IPSEC) != 0 ? 1 : 0);
717 }
718 
719 INITFN void
720 ipe4_attach(void)
721 {
722 
723 	ipipstat_percpu = percpu_alloc(sizeof(uint64_t) * IPIP_NSTATS);
724 
725 	xform_register(&ipe4_xformsw);
726 	/* attach to encapsulation framework */
727 	/* XXX save return cookie for detach on module remove */
728 
729 	encapinit();
730 	/* This function is called before ifinit(). Who else gets lock? */
731 	(void)encap_lock_enter();
732 	/* ipe4_encapsw and ipe4_encapsw must be added atomically */
733 #ifdef INET
734 	(void) encap_attach_func(AF_INET, -1,
735 		ipe4_encapcheck, &ipe4_encapsw, NULL);
736 #endif
737 #ifdef INET6
738 	(void) encap_attach_func(AF_INET6, -1,
739 		ipe4_encapcheck, &ipe4_encapsw6, NULL);
740 #endif
741 	encap_lock_exit();
742 }
743 
744 #ifdef SYSINIT
745 SYSINIT(ipe4_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, ipe4_attach, NULL);
746 #endif
747 
748