xref: /freebsd/sys/netinet6/ip6_input.c (revision 40faf87894ff67ffdf8126fce9bb438ddf61a26f)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the project nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  *	$KAME: ip6_input.c,v 1.259 2002/01/21 04:58:09 jinmei Exp $
32  */
33 
34 /*-
35  * Copyright (c) 1982, 1986, 1988, 1993
36  *	The Regents of the University of California.  All rights reserved.
37  *
38  * Redistribution and use in source and binary forms, with or without
39  * modification, are permitted provided that the following conditions
40  * are met:
41  * 1. Redistributions of source code must retain the above copyright
42  *    notice, this list of conditions and the following disclaimer.
43  * 2. Redistributions in binary form must reproduce the above copyright
44  *    notice, this list of conditions and the following disclaimer in the
45  *    documentation and/or other materials provided with the distribution.
46  * 3. Neither the name of the University nor the names of its contributors
47  *    may be used to endorse or promote products derived from this software
48  *    without specific prior written permission.
49  *
50  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
60  * SUCH DAMAGE.
61  */
62 
63 #include <sys/cdefs.h>
64 #include "opt_inet.h"
65 #include "opt_inet6.h"
66 #include "opt_ipsec.h"
67 #include "opt_route.h"
68 #include "opt_rss.h"
69 #include "opt_sctp.h"
70 
71 #include <sys/param.h>
72 #include <sys/systm.h>
73 #include <sys/hhook.h>
74 #include <sys/malloc.h>
75 #include <sys/mbuf.h>
76 #include <sys/proc.h>
77 #include <sys/domain.h>
78 #include <sys/protosw.h>
79 #include <sys/sdt.h>
80 #include <sys/socket.h>
81 #include <sys/socketvar.h>
82 #include <sys/errno.h>
83 #include <sys/time.h>
84 #include <sys/kernel.h>
85 #include <sys/lock.h>
86 #include <sys/rmlock.h>
87 #include <sys/syslog.h>
88 #include <sys/sysctl.h>
89 #include <sys/eventhandler.h>
90 
91 #include <net/if.h>
92 #include <net/if_var.h>
93 #include <net/if_types.h>
94 #include <net/if_private.h>
95 #include <net/if_dl.h>
96 #include <net/route.h>
97 #include <net/netisr.h>
98 #include <net/rss_config.h>
99 #include <net/pfil.h>
100 #include <net/vnet.h>
101 
102 #include <netinet/in.h>
103 #include <netinet/in_kdtrace.h>
104 #include <netinet/ip_var.h>
105 #include <netinet/in_systm.h>
106 #include <net/if_llatbl.h>
107 #ifdef INET
108 #include <netinet/ip.h>
109 #include <netinet/ip_icmp.h>
110 #endif /* INET */
111 #include <netinet/ip6.h>
112 #include <netinet6/in6_var.h>
113 #include <netinet6/ip6_var.h>
114 #include <netinet/ip_encap.h>
115 #include <netinet/in_pcb.h>
116 #include <netinet/icmp6.h>
117 #include <netinet6/scope6_var.h>
118 #include <netinet6/in6_ifattach.h>
119 #include <netinet6/mld6_var.h>
120 #include <netinet6/nd6.h>
121 #include <netinet6/in6_rss.h>
122 #ifdef SCTP
123 #include <netinet/sctp_pcb.h>
124 #include <netinet6/sctp6_var.h>
125 #endif
126 
127 #include <netipsec/ipsec_support.h>
128 
129 ip6proto_input_t	*ip6_protox[IPPROTO_MAX] = {
130 			    [0 ... IPPROTO_MAX - 1] = rip6_input };
131 ip6proto_ctlinput_t	*ip6_ctlprotox[IPPROTO_MAX] = {
132 			    [0 ... IPPROTO_MAX - 1] = rip6_ctlinput };
133 
134 VNET_DEFINE(struct in6_ifaddrhead, in6_ifaddrhead);
135 VNET_DEFINE(struct in6_ifaddrlisthead *, in6_ifaddrhashtbl);
136 VNET_DEFINE(u_long, in6_ifaddrhmask);
137 
138 static struct netisr_handler ip6_nh = {
139 	.nh_name = "ip6",
140 	.nh_handler = ip6_input,
141 	.nh_proto = NETISR_IPV6,
142 #ifdef RSS
143 	.nh_m2cpuid = rss_soft_m2cpuid_v6,
144 	.nh_policy = NETISR_POLICY_CPU,
145 	.nh_dispatch = NETISR_DISPATCH_HYBRID,
146 #else
147 	.nh_policy = NETISR_POLICY_FLOW,
148 #endif
149 };
150 
151 static int
152 sysctl_netinet6_intr_queue_maxlen(SYSCTL_HANDLER_ARGS)
153 {
154 	int error, qlimit;
155 
156 	netisr_getqlimit(&ip6_nh, &qlimit);
157 	error = sysctl_handle_int(oidp, &qlimit, 0, req);
158 	if (error || !req->newptr)
159 		return (error);
160 	if (qlimit < 1)
161 		return (EINVAL);
162 	return (netisr_setqlimit(&ip6_nh, qlimit));
163 }
164 SYSCTL_DECL(_net_inet6_ip6);
165 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_INTRQMAXLEN, intr_queue_maxlen,
166     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
167     0, 0, sysctl_netinet6_intr_queue_maxlen, "I",
168     "Maximum size of the IPv6 input queue");
169 
170 VNET_DEFINE_STATIC(bool, ip6_sav) = true;
171 #define	V_ip6_sav	VNET(ip6_sav)
172 SYSCTL_BOOL(_net_inet6_ip6, OID_AUTO, source_address_validation,
173     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_sav), true,
174     "Drop incoming packets with source address that is a local address");
175 
176 #ifdef RSS
177 static struct netisr_handler ip6_direct_nh = {
178 	.nh_name = "ip6_direct",
179 	.nh_handler = ip6_direct_input,
180 	.nh_proto = NETISR_IPV6_DIRECT,
181 	.nh_m2cpuid = rss_soft_m2cpuid_v6,
182 	.nh_policy = NETISR_POLICY_CPU,
183 	.nh_dispatch = NETISR_DISPATCH_HYBRID,
184 };
185 
186 static int
187 sysctl_netinet6_intr_direct_queue_maxlen(SYSCTL_HANDLER_ARGS)
188 {
189 	int error, qlimit;
190 
191 	netisr_getqlimit(&ip6_direct_nh, &qlimit);
192 	error = sysctl_handle_int(oidp, &qlimit, 0, req);
193 	if (error || !req->newptr)
194 		return (error);
195 	if (qlimit < 1)
196 		return (EINVAL);
197 	return (netisr_setqlimit(&ip6_direct_nh, qlimit));
198 }
199 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_INTRDQMAXLEN, intr_direct_queue_maxlen,
200     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
201     0, 0, sysctl_netinet6_intr_direct_queue_maxlen, "I",
202     "Maximum size of the IPv6 direct input queue");
203 
204 #endif
205 
206 VNET_DEFINE(pfil_head_t, inet6_pfil_head);
207 VNET_DEFINE(pfil_head_t, inet6_local_pfil_head);
208 
209 VNET_PCPUSTAT_DEFINE(struct ip6stat, ip6stat);
210 VNET_PCPUSTAT_SYSINIT(ip6stat);
211 #ifdef VIMAGE
212 VNET_PCPUSTAT_SYSUNINIT(ip6stat);
213 #endif /* VIMAGE */
214 
215 struct rmlock in6_ifaddr_lock;
216 RM_SYSINIT(in6_ifaddr_lock, &in6_ifaddr_lock, "in6_ifaddr_lock");
217 
218 static int ip6_hopopts_input(u_int32_t *, u_int32_t *, struct mbuf **, int *);
219 
220 /*
221  * IP6 initialization: fill in IP6 protocol switch table.
222  * All protocols not implemented in kernel go to raw IP6 protocol handler.
223  */
224 static void
225 ip6_vnet_init(void *arg __unused)
226 {
227 	struct pfil_head_args args;
228 
229 	TUNABLE_INT_FETCH("net.inet6.ip6.auto_linklocal",
230 	    &V_ip6_auto_linklocal);
231 	TUNABLE_INT_FETCH("net.inet6.ip6.accept_rtadv", &V_ip6_accept_rtadv);
232 	TUNABLE_INT_FETCH("net.inet6.ip6.no_radr", &V_ip6_no_radr);
233 
234 	CK_STAILQ_INIT(&V_in6_ifaddrhead);
235 	V_in6_ifaddrhashtbl = hashinit(IN6ADDR_NHASH, M_IFADDR,
236 	    &V_in6_ifaddrhmask);
237 
238 	/* Initialize packet filter hooks. */
239 	args.pa_version = PFIL_VERSION;
240 	args.pa_flags = PFIL_IN | PFIL_OUT;
241 	args.pa_type = PFIL_TYPE_IP6;
242 	args.pa_headname = PFIL_INET6_NAME;
243 	V_inet6_pfil_head = pfil_head_register(&args);
244 
245 	args.pa_flags = PFIL_OUT;
246 	args.pa_headname = PFIL_INET6_LOCAL_NAME;
247 	V_inet6_local_pfil_head = pfil_head_register(&args);
248 
249 	if (hhook_head_register(HHOOK_TYPE_IPSEC_IN, AF_INET6,
250 	    &V_ipsec_hhh_in[HHOOK_IPSEC_INET6],
251 	    HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
252 		printf("%s: WARNING: unable to register input helper hook\n",
253 		    __func__);
254 	if (hhook_head_register(HHOOK_TYPE_IPSEC_OUT, AF_INET6,
255 	    &V_ipsec_hhh_out[HHOOK_IPSEC_INET6],
256 	    HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
257 		printf("%s: WARNING: unable to register output helper hook\n",
258 		    __func__);
259 
260 	scope6_init();
261 	addrsel_policy_init();
262 	nd6_init();
263 	frag6_init();
264 
265 	V_ip6_desync_factor = arc4random() % MAX_TEMP_DESYNC_FACTOR;
266 
267 	/* Skip global initialization stuff for non-default instances. */
268 #ifdef VIMAGE
269 	netisr_register_vnet(&ip6_nh);
270 #ifdef RSS
271 	netisr_register_vnet(&ip6_direct_nh);
272 #endif
273 #endif
274 }
275 VNET_SYSINIT(ip6_vnet_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH,
276     ip6_vnet_init, NULL);
277 
278 static void
279 ip6_init(void *arg __unused)
280 {
281 
282 	/*
283 	 * Register statically those protocols that are unlikely to ever go
284 	 * dynamic.
285 	 */
286 	IP6PROTO_REGISTER(IPPROTO_ICMPV6, icmp6_input, rip6_ctlinput);
287 	IP6PROTO_REGISTER(IPPROTO_DSTOPTS, dest6_input, NULL);
288 	IP6PROTO_REGISTER(IPPROTO_ROUTING, route6_input, NULL);
289 	IP6PROTO_REGISTER(IPPROTO_FRAGMENT, frag6_input, NULL);
290 	IP6PROTO_REGISTER(IPPROTO_IPV4, encap6_input, NULL);
291 	IP6PROTO_REGISTER(IPPROTO_IPV6, encap6_input, NULL);
292 	IP6PROTO_REGISTER(IPPROTO_ETHERIP, encap6_input, NULL);
293 	IP6PROTO_REGISTER(IPPROTO_GRE, encap6_input, NULL);
294 	IP6PROTO_REGISTER(IPPROTO_PIM, encap6_input, NULL);
295 #ifdef SCTP	/* XXX: has a loadable & static version */
296 	IP6PROTO_REGISTER(IPPROTO_SCTP, sctp6_input, sctp6_ctlinput);
297 #endif
298 
299 	EVENTHANDLER_REGISTER(vm_lowmem, frag6_drain, NULL, LOWMEM_PRI_DEFAULT);
300 	EVENTHANDLER_REGISTER(mbuf_lowmem, frag6_drain, NULL,
301 	    LOWMEM_PRI_DEFAULT);
302 
303 	netisr_register(&ip6_nh);
304 #ifdef RSS
305 	netisr_register(&ip6_direct_nh);
306 #endif
307 }
308 SYSINIT(ip6_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, ip6_init, NULL);
309 
310 int
311 ip6proto_register(uint8_t proto, ip6proto_input_t input,
312     ip6proto_ctlinput_t ctl)
313 {
314 
315 	MPASS(proto > 0);
316 
317 	if (ip6_protox[proto] == rip6_input) {
318 		ip6_protox[proto] = input;
319 		ip6_ctlprotox[proto] = ctl;
320 		return (0);
321 	} else
322 		return (EEXIST);
323 }
324 
325 int
326 ip6proto_unregister(uint8_t proto)
327 {
328 
329 	MPASS(proto > 0);
330 
331 	if (ip6_protox[proto] != rip6_input) {
332 		ip6_protox[proto] = rip6_input;
333 		ip6_ctlprotox[proto] = rip6_ctlinput;
334 		return (0);
335 	} else
336 		return (ENOENT);
337 }
338 
339 #ifdef VIMAGE
340 static void
341 ip6_destroy(void *unused __unused)
342 {
343 	struct ifaddr *ifa, *nifa;
344 	struct ifnet *ifp;
345 	int error;
346 
347 #ifdef RSS
348 	netisr_unregister_vnet(&ip6_direct_nh);
349 #endif
350 	netisr_unregister_vnet(&ip6_nh);
351 
352 	pfil_head_unregister(V_inet6_pfil_head);
353 	error = hhook_head_deregister(V_ipsec_hhh_in[HHOOK_IPSEC_INET6]);
354 	if (error != 0) {
355 		printf("%s: WARNING: unable to deregister input helper hook "
356 		    "type HHOOK_TYPE_IPSEC_IN, id HHOOK_IPSEC_INET6: "
357 		    "error %d returned\n", __func__, error);
358 	}
359 	error = hhook_head_deregister(V_ipsec_hhh_out[HHOOK_IPSEC_INET6]);
360 	if (error != 0) {
361 		printf("%s: WARNING: unable to deregister output helper hook "
362 		    "type HHOOK_TYPE_IPSEC_OUT, id HHOOK_IPSEC_INET6: "
363 		    "error %d returned\n", __func__, error);
364 	}
365 
366 	/* Cleanup addresses. */
367 	IFNET_RLOCK();
368 	CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
369 		/* Cannot lock here - lock recursion. */
370 		/* IF_ADDR_LOCK(ifp); */
371 		CK_STAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, nifa) {
372 			if (ifa->ifa_addr->sa_family != AF_INET6)
373 				continue;
374 			in6_purgeaddr(ifa);
375 		}
376 		/* IF_ADDR_UNLOCK(ifp); */
377 		in6_ifdetach_destroy(ifp);
378 		mld_domifdetach(ifp);
379 	}
380 	IFNET_RUNLOCK();
381 
382 	/* Make sure any routes are gone as well. */
383 	rib_flush_routes_family(AF_INET6);
384 
385 	frag6_destroy();
386 	nd6_destroy();
387 	in6_ifattach_destroy();
388 
389 	hashdestroy(V_in6_ifaddrhashtbl, M_IFADDR, V_in6_ifaddrhmask);
390 }
391 
392 VNET_SYSUNINIT(inet6, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, ip6_destroy, NULL);
393 #endif
394 
395 static int
396 ip6_input_hbh(struct mbuf **mp, uint32_t *plen, uint32_t *rtalert, int *off,
397     int *nxt, int *ours)
398 {
399 	struct mbuf *m;
400 	struct ip6_hdr *ip6;
401 	struct ip6_hbh *hbh;
402 
403 	if (ip6_hopopts_input(plen, rtalert, mp, off)) {
404 #if 0	/*touches NULL pointer*/
405 		in6_ifstat_inc((*mp)->m_pkthdr.rcvif, ifs6_in_discard);
406 #endif
407 		goto out;	/* m have already been freed */
408 	}
409 
410 	/* adjust pointer */
411 	m = *mp;
412 	ip6 = mtod(m, struct ip6_hdr *);
413 
414 	/*
415 	 * if the payload length field is 0 and the next header field
416 	 * indicates Hop-by-Hop Options header, then a Jumbo Payload
417 	 * option MUST be included.
418 	 */
419 	if (ip6->ip6_plen == 0 && *plen == 0) {
420 		/*
421 		 * Note that if a valid jumbo payload option is
422 		 * contained, ip6_hopopts_input() must set a valid
423 		 * (non-zero) payload length to the variable plen.
424 		 */
425 		IP6STAT_INC(ip6s_badoptions);
426 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
427 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
428 		icmp6_error(m, ICMP6_PARAM_PROB,
429 			    ICMP6_PARAMPROB_HEADER,
430 			    (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
431 		goto out;
432 	}
433 	/* ip6_hopopts_input() ensures that mbuf is contiguous */
434 	hbh = (struct ip6_hbh *)(ip6 + 1);
435 	*nxt = hbh->ip6h_nxt;
436 
437 	/*
438 	 * If we are acting as a router and the packet contains a
439 	 * router alert option, see if we know the option value.
440 	 * Currently, we only support the option value for MLD, in which
441 	 * case we should pass the packet to the multicast routing
442 	 * daemon.
443 	 */
444 	if (*rtalert != ~0) {
445 		switch (*rtalert) {
446 		case IP6OPT_RTALERT_MLD:
447 			if (V_ip6_forwarding)
448 				*ours = 1;
449 			break;
450 		default:
451 			/*
452 			 * RFC2711 requires unrecognized values must be
453 			 * silently ignored.
454 			 */
455 			break;
456 		}
457 	}
458 
459 	return (0);
460 
461 out:
462 	return (1);
463 }
464 
465 #ifdef RSS
466 /*
467  * IPv6 direct input routine.
468  *
469  * This is called when reinjecting completed fragments where
470  * all of the previous checking and book-keeping has been done.
471  */
472 void
473 ip6_direct_input(struct mbuf *m)
474 {
475 	int off, nxt;
476 	int nest;
477 	struct m_tag *mtag;
478 	struct ip6_direct_ctx *ip6dc;
479 
480 	mtag = m_tag_locate(m, MTAG_ABI_IPV6, IPV6_TAG_DIRECT, NULL);
481 	KASSERT(mtag != NULL, ("Reinjected packet w/o direct ctx tag!"));
482 
483 	ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
484 	nxt = ip6dc->ip6dc_nxt;
485 	off = ip6dc->ip6dc_off;
486 
487 	nest = 0;
488 
489 	m_tag_delete(m, mtag);
490 
491 	while (nxt != IPPROTO_DONE) {
492 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
493 			IP6STAT_INC(ip6s_toomanyhdr);
494 			goto bad;
495 		}
496 
497 		/*
498 		 * protection against faulty packet - there should be
499 		 * more sanity checks in header chain processing.
500 		 */
501 		if (m->m_pkthdr.len < off) {
502 			IP6STAT_INC(ip6s_tooshort);
503 			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
504 			goto bad;
505 		}
506 
507 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
508 		if (IPSEC_ENABLED(ipv6)) {
509 			if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
510 				return;
511 		}
512 #endif /* IPSEC */
513 
514 		nxt = ip6_protox[nxt](&m, &off, nxt);
515 	}
516 	return;
517 bad:
518 	m_freem(m);
519 }
520 #endif
521 
522 void
523 ip6_input(struct mbuf *m)
524 {
525 	struct in6_addr odst;
526 	struct ip6_hdr *ip6;
527 	struct in6_ifaddr *ia;
528 	struct ifnet *rcvif;
529 	u_int32_t plen;
530 	u_int32_t rtalert = ~0;
531 	int off = sizeof(struct ip6_hdr), nest;
532 	int nxt, ours = 0;
533 	int srcrt = 0;
534 
535 	/*
536 	 * Drop the packet if IPv6 operation is disabled on the interface.
537 	 */
538 	rcvif = m->m_pkthdr.rcvif;
539 	if ((ND_IFINFO(rcvif)->flags & ND6_IFF_IFDISABLED))
540 		goto bad;
541 
542 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
543 	/*
544 	 * should the inner packet be considered authentic?
545 	 * see comment in ah4_input().
546 	 * NB: m cannot be NULL when passed to the input routine
547 	 */
548 
549 	m->m_flags &= ~M_AUTHIPHDR;
550 	m->m_flags &= ~M_AUTHIPDGM;
551 
552 #endif /* IPSEC */
553 
554 	if (m->m_flags & M_FASTFWD_OURS) {
555 		/*
556 		 * Firewall changed destination to local.
557 		 */
558 		ip6 = mtod(m, struct ip6_hdr *);
559 		goto passin;
560 	}
561 
562 	/*
563 	 * mbuf statistics
564 	 */
565 	if (m->m_flags & M_EXT) {
566 		if (m->m_next)
567 			IP6STAT_INC(ip6s_mext2m);
568 		else
569 			IP6STAT_INC(ip6s_mext1);
570 	} else {
571 		if (m->m_next) {
572 			struct ifnet *ifp = (m->m_flags & M_LOOP) ? V_loif : rcvif;
573 			int ifindex = ifp->if_index;
574 			if (ifindex >= IP6S_M2MMAX)
575 				ifindex = 0;
576 			IP6STAT_INC2(ip6s_m2m, ifindex);
577 		} else
578 			IP6STAT_INC(ip6s_m1);
579 	}
580 
581 	in6_ifstat_inc(rcvif, ifs6_in_receive);
582 	IP6STAT_INC(ip6s_total);
583 
584 	/*
585 	 * L2 bridge code and some other code can return mbuf chain
586 	 * that does not conform to KAME requirement.  too bad.
587 	 * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
588 	 */
589 	if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
590 		struct mbuf *n;
591 
592 		if (m->m_pkthdr.len > MHLEN)
593 			n = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
594 		else
595 			n = m_gethdr(M_NOWAIT, MT_DATA);
596 		if (n == NULL)
597 			goto bad;
598 
599 		m_move_pkthdr(n, m);
600 		m_copydata(m, 0, n->m_pkthdr.len, mtod(n, caddr_t));
601 		n->m_len = n->m_pkthdr.len;
602 		m_freem(m);
603 		m = n;
604 	}
605 	if (m->m_len < sizeof(struct ip6_hdr)) {
606 		if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
607 			IP6STAT_INC(ip6s_toosmall);
608 			in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
609 			goto bad;
610 		}
611 	}
612 
613 	ip6 = mtod(m, struct ip6_hdr *);
614 	if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
615 		IP6STAT_INC(ip6s_badvers);
616 		in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
617 		goto bad;
618 	}
619 
620 	IP6STAT_INC2(ip6s_nxthist, ip6->ip6_nxt);
621 	IP_PROBE(receive, NULL, NULL, ip6, rcvif, NULL, ip6);
622 
623 	/*
624 	 * Check against address spoofing/corruption.  The unspecified address
625 	 * is checked further below.
626 	 */
627 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) {
628 		/*
629 		 * XXX: "badscope" is not very suitable for a multicast source.
630 		 */
631 		IP6STAT_INC(ip6s_badscope);
632 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
633 		goto bad;
634 	}
635 	if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) &&
636 	    !(m->m_flags & M_LOOP)) {
637 		/*
638 		 * In this case, the packet should come from the loopback
639 		 * interface.  However, we cannot just check the if_flags,
640 		 * because ip6_mloopback() passes the "actual" interface
641 		 * as the outgoing/incoming interface.
642 		 */
643 		IP6STAT_INC(ip6s_badscope);
644 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
645 		goto bad;
646 	}
647 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) &&
648 	    IPV6_ADDR_MC_SCOPE(&ip6->ip6_dst) == 0) {
649 		/*
650 		 * RFC4291 2.7:
651 		 * Nodes must not originate a packet to a multicast address
652 		 * whose scop field contains the reserved value 0; if such
653 		 * a packet is received, it must be silently dropped.
654 		 */
655 		IP6STAT_INC(ip6s_badscope);
656 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
657 		goto bad;
658 	}
659 	/*
660 	 * The following check is not documented in specs.  A malicious
661 	 * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
662 	 * and bypass security checks (act as if it was from 127.0.0.1 by using
663 	 * IPv6 src ::ffff:127.0.0.1).  Be cautious.
664 	 *
665 	 * We have supported IPv6-only kernels for a few years and this issue
666 	 * has not come up.  The world seems to move mostly towards not using
667 	 * v4mapped on the wire, so it makes sense for us to keep rejecting
668 	 * any such packets.
669 	 */
670 	if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
671 	    IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
672 		IP6STAT_INC(ip6s_badscope);
673 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
674 		goto bad;
675 	}
676 #if 0
677 	/*
678 	 * Reject packets with IPv4 compatible addresses (auto tunnel).
679 	 *
680 	 * The code forbids auto tunnel relay case in RFC1933 (the check is
681 	 * stronger than RFC1933).  We may want to re-enable it if mech-xx
682 	 * is revised to forbid relaying case.
683 	 */
684 	if (IN6_IS_ADDR_V4COMPAT(&ip6->ip6_src) ||
685 	    IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
686 		IP6STAT_INC(ip6s_badscope);
687 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
688 		goto bad;
689 	}
690 #endif
691 	/*
692 	 * Try to forward the packet, but if we fail continue.
693 	 * ip6_tryforward() does not generate redirects, so fall
694 	 * through to normal processing if redirects are required.
695 	 * ip6_tryforward() does inbound and outbound packet firewall
696 	 * processing. If firewall has decided that destination becomes
697 	 * our local address, it sets M_FASTFWD_OURS flag. In this
698 	 * case skip another inbound firewall processing and update
699 	 * ip6 pointer.
700 	 */
701 	if (V_ip6_forwarding != 0 && V_ip6_sendredirects == 0
702 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
703 	    && (!IPSEC_ENABLED(ipv6) ||
704 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_OPERABLE) == 0)
705 #endif
706 	    ) {
707 		if ((m = ip6_tryforward(m)) == NULL)
708 			return;
709 		if (m->m_flags & M_FASTFWD_OURS) {
710 			ip6 = mtod(m, struct ip6_hdr *);
711 			goto passin;
712 		}
713 	}
714 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
715 	/*
716 	 * Bypass packet filtering for packets previously handled by IPsec.
717 	 */
718 	if (IPSEC_ENABLED(ipv6) &&
719 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_BYPASS_FILTER) != 0)
720 			goto passin;
721 #endif
722 	/*
723 	 * Run through list of hooks for input packets.
724 	 *
725 	 * NB: Beware of the destination address changing
726 	 *     (e.g. by NAT rewriting).  When this happens,
727 	 *     tell ip6_forward to do the right thing.
728 	 */
729 
730 	/* Jump over all PFIL processing if hooks are not active. */
731 	if (!PFIL_HOOKED_IN(V_inet6_pfil_head))
732 		goto passin;
733 
734 	odst = ip6->ip6_dst;
735 	if (pfil_mbuf_in(V_inet6_pfil_head, &m, m->m_pkthdr.rcvif,
736 	    NULL) != PFIL_PASS)
737 		return;
738 	ip6 = mtod(m, struct ip6_hdr *);
739 	srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
740 	if ((m->m_flags & (M_IP6_NEXTHOP | M_FASTFWD_OURS)) == M_IP6_NEXTHOP &&
741 	    m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL) {
742 		/*
743 		 * Directly ship the packet on.  This allows forwarding
744 		 * packets originally destined to us to some other directly
745 		 * connected host.
746 		 */
747 		ip6_forward(m, 1);
748 		return;
749 	}
750 
751 passin:
752 	/*
753 	 * The check is deferred to here to give firewalls a chance to block
754 	 * (and log) such packets.  ip6_tryforward() will not process such
755 	 * packets.
756 	 */
757 	if (__predict_false(IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst))) {
758 		IP6STAT_INC(ip6s_badscope);
759 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
760 		goto bad;
761 	}
762 
763 	/*
764 	 * Disambiguate address scope zones (if there is ambiguity).
765 	 * We first make sure that the original source or destination address
766 	 * is not in our internal form for scoped addresses.  Such addresses
767 	 * are not necessarily invalid spec-wise, but we cannot accept them due
768 	 * to the usage conflict.
769 	 * in6_setscope() then also checks and rejects the cases where src or
770 	 * dst are the loopback address and the receiving interface
771 	 * is not loopback.
772 	 */
773 	if (in6_clearscope(&ip6->ip6_src) || in6_clearscope(&ip6->ip6_dst)) {
774 		IP6STAT_INC(ip6s_badscope); /* XXX */
775 		goto bad;
776 	}
777 	if (in6_setscope(&ip6->ip6_src, rcvif, NULL) ||
778 	    in6_setscope(&ip6->ip6_dst, rcvif, NULL)) {
779 		IP6STAT_INC(ip6s_badscope);
780 		goto bad;
781 	}
782 	if (m->m_flags & M_FASTFWD_OURS) {
783 		m->m_flags &= ~M_FASTFWD_OURS;
784 		ours = 1;
785 		goto hbhcheck;
786 	}
787 	/*
788 	 * Multicast check. Assume packet is for us to avoid
789 	 * prematurely taking locks.
790 	 */
791 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
792 		ours = 1;
793 		in6_ifstat_inc(rcvif, ifs6_in_mcast);
794 		goto hbhcheck;
795 	}
796 	/*
797 	 * Unicast check
798 	 * XXX: For now we keep link-local IPv6 addresses with embedded
799 	 *      scope zone id, therefore we use zero zoneid here.
800 	 */
801 	ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false);
802 	if (ia != NULL) {
803 		if (ia->ia6_flags & IN6_IFF_NOTREADY) {
804 			char ip6bufs[INET6_ADDRSTRLEN];
805 			char ip6bufd[INET6_ADDRSTRLEN];
806 			/* address is not ready, so discard the packet. */
807 			nd6log((LOG_INFO,
808 			    "ip6_input: packet to an unready address %s->%s\n",
809 			    ip6_sprintf(ip6bufs, &ip6->ip6_src),
810 			    ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
811 			goto bad;
812 		}
813 		if (V_ip6_sav && !(m->m_flags & M_LOOP) &&
814 		    __predict_false(in6_localip_fib(&ip6->ip6_src,
815 			    rcvif->if_fib))) {
816 			IP6STAT_INC(ip6s_badscope); /* XXX */
817 			goto bad;
818 		}
819 		/* Count the packet in the ip address stats */
820 		counter_u64_add(ia->ia_ifa.ifa_ipackets, 1);
821 		counter_u64_add(ia->ia_ifa.ifa_ibytes, m->m_pkthdr.len);
822 		ours = 1;
823 		goto hbhcheck;
824 	}
825 
826 	/*
827 	 * Now there is no reason to process the packet if it's not our own
828 	 * and we're not a router.
829 	 */
830 	if (!V_ip6_forwarding) {
831 		IP6STAT_INC(ip6s_cantforward);
832 		goto bad;
833 	}
834 
835   hbhcheck:
836 	/*
837 	 * Process Hop-by-Hop options header if it's contained.
838 	 * m may be modified in ip6_hopopts_input().
839 	 * If a JumboPayload option is included, plen will also be modified.
840 	 */
841 	plen = (u_int32_t)ntohs(ip6->ip6_plen);
842 	if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
843 		if (ip6_input_hbh(&m, &plen, &rtalert, &off, &nxt, &ours) != 0)
844 			return;
845 	} else
846 		nxt = ip6->ip6_nxt;
847 
848 	/*
849 	 * Use mbuf flags to propagate Router Alert option to
850 	 * ICMPv6 layer, as hop-by-hop options have been stripped.
851 	 */
852 	if (rtalert != ~0)
853 		m->m_flags |= M_RTALERT_MLD;
854 
855 	/*
856 	 * Check that the amount of data in the buffers
857 	 * is as at least much as the IPv6 header would have us expect.
858 	 * Trim mbufs if longer than we expect.
859 	 * Drop packet if shorter than we expect.
860 	 */
861 	if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
862 		IP6STAT_INC(ip6s_tooshort);
863 		in6_ifstat_inc(rcvif, ifs6_in_truncated);
864 		goto bad;
865 	}
866 	if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
867 		if (m->m_len == m->m_pkthdr.len) {
868 			m->m_len = sizeof(struct ip6_hdr) + plen;
869 			m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
870 		} else
871 			m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
872 	}
873 
874 	/*
875 	 * Forward if desirable.
876 	 */
877 	if (V_ip6_mrouter &&
878 	    IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
879 		/*
880 		 * If we are acting as a multicast router, all
881 		 * incoming multicast packets are passed to the
882 		 * kernel-level multicast forwarding function.
883 		 * The packet is returned (relatively) intact; if
884 		 * ip6_mforward() returns a non-zero value, the packet
885 		 * must be discarded, else it may be accepted below.
886 		 *
887 		 * XXX TODO: Check hlim and multicast scope here to avoid
888 		 * unnecessarily calling into ip6_mforward().
889 		 */
890 		if (ip6_mforward && ip6_mforward(ip6, rcvif, m)) {
891 			IP6STAT_INC(ip6s_cantforward);
892 			goto bad;
893 		}
894 	} else if (!ours) {
895 		ip6_forward(m, srcrt);
896 		return;
897 	}
898 
899 	/*
900 	 * We are going to ship the packet to the local protocol stack. Call the
901 	 * filter again for this 'output' action, allowing redirect-like rules
902 	 * to adjust the source address.
903 	 */
904 	if (PFIL_HOOKED_OUT(V_inet6_local_pfil_head)) {
905 		if (pfil_mbuf_out(V_inet6_local_pfil_head, &m, V_loif, NULL) !=
906 		    PFIL_PASS)
907 			return;
908 		ip6 = mtod(m, struct ip6_hdr *);
909 	}
910 
911 	/*
912 	 * Tell launch routine the next header
913 	 */
914 	IP6STAT_INC(ip6s_delivered);
915 	in6_ifstat_inc(rcvif, ifs6_in_deliver);
916 	nest = 0;
917 
918 	while (nxt != IPPROTO_DONE) {
919 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
920 			IP6STAT_INC(ip6s_toomanyhdr);
921 			goto bad;
922 		}
923 
924 		/*
925 		 * protection against faulty packet - there should be
926 		 * more sanity checks in header chain processing.
927 		 */
928 		if (m->m_pkthdr.len < off) {
929 			IP6STAT_INC(ip6s_tooshort);
930 			in6_ifstat_inc(rcvif, ifs6_in_truncated);
931 			goto bad;
932 		}
933 
934 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
935 		if (IPSEC_ENABLED(ipv6)) {
936 			if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
937 				return;
938 		}
939 #endif /* IPSEC */
940 
941 		nxt = ip6_protox[nxt](&m, &off, nxt);
942 	}
943 	return;
944 bad:
945 	in6_ifstat_inc(rcvif, ifs6_in_discard);
946 	if (m != NULL)
947 		m_freem(m);
948 }
949 
950 /*
951  * Hop-by-Hop options header processing. If a valid jumbo payload option is
952  * included, the real payload length will be stored in plenp.
953  *
954  * rtalertp - XXX: should be stored more smart way
955  */
956 static int
957 ip6_hopopts_input(u_int32_t *plenp, u_int32_t *rtalertp,
958     struct mbuf **mp, int *offp)
959 {
960 	struct mbuf *m = *mp;
961 	int off = *offp, hbhlen;
962 	struct ip6_hbh *hbh;
963 
964 	/* validation of the length of the header */
965 	if (m->m_len < off + sizeof(*hbh)) {
966 		m = m_pullup(m, off + sizeof(*hbh));
967 		if (m == NULL) {
968 			IP6STAT_INC(ip6s_exthdrtoolong);
969 			*mp = NULL;
970 			return (-1);
971 		}
972 	}
973 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
974 	hbhlen = (hbh->ip6h_len + 1) << 3;
975 
976 	if (m->m_len < off + hbhlen) {
977 		m = m_pullup(m, off + hbhlen);
978 		if (m == NULL) {
979 			IP6STAT_INC(ip6s_exthdrtoolong);
980 			*mp = NULL;
981 			return (-1);
982 		}
983 	}
984 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
985 	off += hbhlen;
986 	hbhlen -= sizeof(struct ip6_hbh);
987 	if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
988 				hbhlen, rtalertp, plenp) < 0) {
989 		*mp = NULL;
990 		return (-1);
991 	}
992 
993 	*offp = off;
994 	*mp = m;
995 	return (0);
996 }
997 
998 /*
999  * Search header for all Hop-by-hop options and process each option.
1000  * This function is separate from ip6_hopopts_input() in order to
1001  * handle a case where the sending node itself process its hop-by-hop
1002  * options header. In such a case, the function is called from ip6_output().
1003  *
1004  * The function assumes that hbh header is located right after the IPv6 header
1005  * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
1006  * opthead + hbhlen is located in contiguous memory region.
1007  */
1008 int
1009 ip6_process_hopopts(struct mbuf *m, u_int8_t *opthead, int hbhlen,
1010     u_int32_t *rtalertp, u_int32_t *plenp)
1011 {
1012 	struct ip6_hdr *ip6;
1013 	int optlen = 0;
1014 	u_int8_t *opt = opthead;
1015 	u_int16_t rtalert_val;
1016 	u_int32_t jumboplen;
1017 	const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);
1018 
1019 	for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
1020 		switch (*opt) {
1021 		case IP6OPT_PAD1:
1022 			optlen = 1;
1023 			break;
1024 		case IP6OPT_PADN:
1025 			if (hbhlen < IP6OPT_MINLEN) {
1026 				IP6STAT_INC(ip6s_toosmall);
1027 				goto bad;
1028 			}
1029 			optlen = *(opt + 1) + 2;
1030 			break;
1031 		case IP6OPT_ROUTER_ALERT:
1032 			/* XXX may need check for alignment */
1033 			if (hbhlen < IP6OPT_RTALERT_LEN) {
1034 				IP6STAT_INC(ip6s_toosmall);
1035 				goto bad;
1036 			}
1037 			if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
1038 				/* XXX stat */
1039 				icmp6_error(m, ICMP6_PARAM_PROB,
1040 				    ICMP6_PARAMPROB_HEADER,
1041 				    erroff + opt + 1 - opthead);
1042 				return (-1);
1043 			}
1044 			optlen = IP6OPT_RTALERT_LEN;
1045 			bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
1046 			*rtalertp = ntohs(rtalert_val);
1047 			break;
1048 		case IP6OPT_JUMBO:
1049 			/* XXX may need check for alignment */
1050 			if (hbhlen < IP6OPT_JUMBO_LEN) {
1051 				IP6STAT_INC(ip6s_toosmall);
1052 				goto bad;
1053 			}
1054 			if (*(opt + 1) != IP6OPT_JUMBO_LEN - 2) {
1055 				/* XXX stat */
1056 				icmp6_error(m, ICMP6_PARAM_PROB,
1057 				    ICMP6_PARAMPROB_HEADER,
1058 				    erroff + opt + 1 - opthead);
1059 				return (-1);
1060 			}
1061 			optlen = IP6OPT_JUMBO_LEN;
1062 
1063 			/*
1064 			 * IPv6 packets that have non 0 payload length
1065 			 * must not contain a jumbo payload option.
1066 			 */
1067 			ip6 = mtod(m, struct ip6_hdr *);
1068 			if (ip6->ip6_plen) {
1069 				IP6STAT_INC(ip6s_badoptions);
1070 				icmp6_error(m, ICMP6_PARAM_PROB,
1071 				    ICMP6_PARAMPROB_HEADER,
1072 				    erroff + opt - opthead);
1073 				return (-1);
1074 			}
1075 
1076 			/*
1077 			 * We may see jumbolen in unaligned location, so
1078 			 * we'd need to perform bcopy().
1079 			 */
1080 			bcopy(opt + 2, &jumboplen, sizeof(jumboplen));
1081 			jumboplen = (u_int32_t)htonl(jumboplen);
1082 
1083 #if 1
1084 			/*
1085 			 * if there are multiple jumbo payload options,
1086 			 * *plenp will be non-zero and the packet will be
1087 			 * rejected.
1088 			 * the behavior may need some debate in ipngwg -
1089 			 * multiple options does not make sense, however,
1090 			 * there's no explicit mention in specification.
1091 			 */
1092 			if (*plenp != 0) {
1093 				IP6STAT_INC(ip6s_badoptions);
1094 				icmp6_error(m, ICMP6_PARAM_PROB,
1095 				    ICMP6_PARAMPROB_HEADER,
1096 				    erroff + opt + 2 - opthead);
1097 				return (-1);
1098 			}
1099 #endif
1100 
1101 			/*
1102 			 * jumbo payload length must be larger than 65535.
1103 			 */
1104 			if (jumboplen <= IPV6_MAXPACKET) {
1105 				IP6STAT_INC(ip6s_badoptions);
1106 				icmp6_error(m, ICMP6_PARAM_PROB,
1107 				    ICMP6_PARAMPROB_HEADER,
1108 				    erroff + opt + 2 - opthead);
1109 				return (-1);
1110 			}
1111 			*plenp = jumboplen;
1112 
1113 			break;
1114 		default:		/* unknown option */
1115 			if (hbhlen < IP6OPT_MINLEN) {
1116 				IP6STAT_INC(ip6s_toosmall);
1117 				goto bad;
1118 			}
1119 			optlen = ip6_unknown_opt(opt, m,
1120 			    erroff + opt - opthead);
1121 			if (optlen == -1)
1122 				return (-1);
1123 			optlen += 2;
1124 			break;
1125 		}
1126 	}
1127 
1128 	return (0);
1129 
1130   bad:
1131 	m_freem(m);
1132 	return (-1);
1133 }
1134 
1135 /*
1136  * Unknown option processing.
1137  * The third argument `off' is the offset from the IPv6 header to the option,
1138  * which is necessary if the IPv6 header the and option header and IPv6 header
1139  * is not contiguous in order to return an ICMPv6 error.
1140  */
1141 int
1142 ip6_unknown_opt(u_int8_t *optp, struct mbuf *m, int off)
1143 {
1144 	struct ip6_hdr *ip6;
1145 
1146 	switch (IP6OPT_TYPE(*optp)) {
1147 	case IP6OPT_TYPE_SKIP: /* ignore the option */
1148 		return ((int)*(optp + 1));
1149 	case IP6OPT_TYPE_DISCARD:	/* silently discard */
1150 		m_freem(m);
1151 		return (-1);
1152 	case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
1153 		IP6STAT_INC(ip6s_badoptions);
1154 		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
1155 		return (-1);
1156 	case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
1157 		IP6STAT_INC(ip6s_badoptions);
1158 		ip6 = mtod(m, struct ip6_hdr *);
1159 		if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
1160 		    (m->m_flags & (M_BCAST|M_MCAST)))
1161 			m_freem(m);
1162 		else
1163 			icmp6_error(m, ICMP6_PARAM_PROB,
1164 				    ICMP6_PARAMPROB_OPTION, off);
1165 		return (-1);
1166 	}
1167 
1168 	m_freem(m);		/* XXX: NOTREACHED */
1169 	return (-1);
1170 }
1171 
1172 /*
1173  * Create the "control" list for this pcb.
1174  * These functions will not modify mbuf chain at all.
1175  *
1176  * The routine will be called from upper layer handlers like tcp6_input().
1177  * Thus the routine assumes that the caller (tcp6_input) have already
1178  * called m_pullup() and all the extension headers are located in the
1179  * very first mbuf on the mbuf chain.
1180  *
1181  * ip6_savecontrol_v4 will handle those options that are possible to be
1182  * set on a v4-mapped socket.
1183  * ip6_savecontrol will directly call ip6_savecontrol_v4 to handle those
1184  * options and handle the v6-only ones itself.
1185  */
1186 struct mbuf **
1187 ip6_savecontrol_v4(struct inpcb *inp, struct mbuf *m, struct mbuf **mp,
1188     int *v4only)
1189 {
1190 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
1191 
1192 #ifdef SO_TIMESTAMP
1193 	if ((inp->inp_socket->so_options & SO_TIMESTAMP) != 0) {
1194 		union {
1195 			struct timeval tv;
1196 			struct bintime bt;
1197 			struct timespec ts;
1198 		} t;
1199 		struct bintime boottimebin, bt1;
1200 		struct timespec ts1;
1201 		bool stamped;
1202 
1203 		stamped = false;
1204 		switch (inp->inp_socket->so_ts_clock) {
1205 		case SO_TS_REALTIME_MICRO:
1206 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1207 			    M_TSTMP)) {
1208 				mbuf_tstmp2timespec(m, &ts1);
1209 				timespec2bintime(&ts1, &bt1);
1210 				getboottimebin(&boottimebin);
1211 				bintime_add(&bt1, &boottimebin);
1212 				bintime2timeval(&bt1, &t.tv);
1213 			} else {
1214 				microtime(&t.tv);
1215 			}
1216 			*mp = sbcreatecontrol(&t.tv, sizeof(t.tv),
1217 			    SCM_TIMESTAMP, SOL_SOCKET, M_NOWAIT);
1218 			if (*mp != NULL) {
1219 				mp = &(*mp)->m_next;
1220 				stamped = true;
1221 			}
1222 			break;
1223 
1224 		case SO_TS_BINTIME:
1225 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1226 			    M_TSTMP)) {
1227 				mbuf_tstmp2timespec(m, &ts1);
1228 				timespec2bintime(&ts1, &t.bt);
1229 				getboottimebin(&boottimebin);
1230 				bintime_add(&t.bt, &boottimebin);
1231 			} else {
1232 				bintime(&t.bt);
1233 			}
1234 			*mp = sbcreatecontrol(&t.bt, sizeof(t.bt), SCM_BINTIME,
1235 			    SOL_SOCKET, M_NOWAIT);
1236 			if (*mp != NULL) {
1237 				mp = &(*mp)->m_next;
1238 				stamped = true;
1239 			}
1240 			break;
1241 
1242 		case SO_TS_REALTIME:
1243 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1244 			    M_TSTMP)) {
1245 				mbuf_tstmp2timespec(m, &t.ts);
1246 				getboottimebin(&boottimebin);
1247 				bintime2timespec(&boottimebin, &ts1);
1248 				timespecadd(&t.ts, &ts1, &t.ts);
1249 			} else {
1250 				nanotime(&t.ts);
1251 			}
1252 			*mp = sbcreatecontrol(&t.ts, sizeof(t.ts),
1253 			    SCM_REALTIME, SOL_SOCKET, M_NOWAIT);
1254 			if (*mp != NULL) {
1255 				mp = &(*mp)->m_next;
1256 				stamped = true;
1257 			}
1258 			break;
1259 
1260 		case SO_TS_MONOTONIC:
1261 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1262 			    M_TSTMP))
1263 				mbuf_tstmp2timespec(m, &t.ts);
1264 			else
1265 				nanouptime(&t.ts);
1266 			*mp = sbcreatecontrol(&t.ts, sizeof(t.ts),
1267 			    SCM_MONOTONIC, SOL_SOCKET, M_NOWAIT);
1268 			if (*mp != NULL) {
1269 				mp = &(*mp)->m_next;
1270 				stamped = true;
1271 			}
1272 			break;
1273 
1274 		default:
1275 			panic("unknown (corrupted) so_ts_clock");
1276 		}
1277 		if (stamped && (m->m_flags & (M_PKTHDR | M_TSTMP)) ==
1278 		    (M_PKTHDR | M_TSTMP)) {
1279 			struct sock_timestamp_info sti;
1280 
1281 			bzero(&sti, sizeof(sti));
1282 			sti.st_info_flags = ST_INFO_HW;
1283 			if ((m->m_flags & M_TSTMP_HPREC) != 0)
1284 				sti.st_info_flags |= ST_INFO_HW_HPREC;
1285 			*mp = sbcreatecontrol(&sti, sizeof(sti), SCM_TIME_INFO,
1286 			    SOL_SOCKET, M_NOWAIT);
1287 			if (*mp != NULL)
1288 				mp = &(*mp)->m_next;
1289 		}
1290 	}
1291 #endif
1292 
1293 #define IS2292(inp, x, y)	(((inp)->inp_flags & IN6P_RFC2292) ? (x) : (y))
1294 	/* RFC 2292 sec. 5 */
1295 	if ((inp->inp_flags & IN6P_PKTINFO) != 0) {
1296 		struct in6_pktinfo pi6;
1297 
1298 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1299 #ifdef INET
1300 			struct ip *ip;
1301 
1302 			ip = mtod(m, struct ip *);
1303 			pi6.ipi6_addr.s6_addr32[0] = 0;
1304 			pi6.ipi6_addr.s6_addr32[1] = 0;
1305 			pi6.ipi6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
1306 			pi6.ipi6_addr.s6_addr32[3] = ip->ip_dst.s_addr;
1307 #else
1308 			/* We won't hit this code */
1309 			bzero(&pi6.ipi6_addr, sizeof(struct in6_addr));
1310 #endif
1311 		} else {
1312 			bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
1313 			in6_clearscope(&pi6.ipi6_addr);	/* XXX */
1314 		}
1315 		pi6.ipi6_ifindex =
1316 		    (m && m->m_pkthdr.rcvif) ? m->m_pkthdr.rcvif->if_index : 0;
1317 
1318 		*mp = sbcreatecontrol(&pi6, sizeof(struct in6_pktinfo),
1319 		    IS2292(inp, IPV6_2292PKTINFO, IPV6_PKTINFO), IPPROTO_IPV6,
1320 		    M_NOWAIT);
1321 		if (*mp)
1322 			mp = &(*mp)->m_next;
1323 	}
1324 
1325 	if ((inp->inp_flags & IN6P_HOPLIMIT) != 0) {
1326 		int hlim;
1327 
1328 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1329 #ifdef INET
1330 			struct ip *ip;
1331 
1332 			ip = mtod(m, struct ip *);
1333 			hlim = ip->ip_ttl;
1334 #else
1335 			/* We won't hit this code */
1336 			hlim = 0;
1337 #endif
1338 		} else {
1339 			hlim = ip6->ip6_hlim & 0xff;
1340 		}
1341 		*mp = sbcreatecontrol(&hlim, sizeof(int),
1342 		    IS2292(inp, IPV6_2292HOPLIMIT, IPV6_HOPLIMIT),
1343 		    IPPROTO_IPV6, M_NOWAIT);
1344 		if (*mp)
1345 			mp = &(*mp)->m_next;
1346 	}
1347 
1348 	if ((inp->inp_flags & IN6P_TCLASS) != 0) {
1349 		int tclass;
1350 
1351 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1352 #ifdef INET
1353 			struct ip *ip;
1354 
1355 			ip = mtod(m, struct ip *);
1356 			tclass = ip->ip_tos;
1357 #else
1358 			/* We won't hit this code */
1359 			tclass = 0;
1360 #endif
1361 		} else {
1362 			u_int32_t flowinfo;
1363 
1364 			flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
1365 			flowinfo >>= 20;
1366 			tclass = flowinfo & 0xff;
1367 		}
1368 		*mp = sbcreatecontrol(&tclass, sizeof(int), IPV6_TCLASS,
1369 		    IPPROTO_IPV6, M_NOWAIT);
1370 		if (*mp)
1371 			mp = &(*mp)->m_next;
1372 	}
1373 
1374 	if (v4only != NULL) {
1375 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1376 			*v4only = 1;
1377 		} else {
1378 			*v4only = 0;
1379 		}
1380 	}
1381 
1382 	return (mp);
1383 }
1384 
1385 void
1386 ip6_savecontrol(struct inpcb *inp, struct mbuf *m, struct mbuf **mp)
1387 {
1388 	struct ip6_hdr *ip6;
1389 	int v4only = 0;
1390 
1391 	mp = ip6_savecontrol_v4(inp, m, mp, &v4only);
1392 	if (v4only)
1393 		return;
1394 
1395 	ip6 = mtod(m, struct ip6_hdr *);
1396 	/*
1397 	 * IPV6_HOPOPTS socket option.  Recall that we required super-user
1398 	 * privilege for the option (see ip6_ctloutput), but it might be too
1399 	 * strict, since there might be some hop-by-hop options which can be
1400 	 * returned to normal user.
1401 	 * See also RFC 2292 section 6 (or RFC 3542 section 8).
1402 	 */
1403 	if ((inp->inp_flags & IN6P_HOPOPTS) != 0) {
1404 		/*
1405 		 * Check if a hop-by-hop options header is contatined in the
1406 		 * received packet, and if so, store the options as ancillary
1407 		 * data. Note that a hop-by-hop options header must be
1408 		 * just after the IPv6 header, which is assured through the
1409 		 * IPv6 input processing.
1410 		 */
1411 		if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
1412 			struct ip6_hbh *hbh;
1413 			u_int hbhlen;
1414 
1415 			hbh = (struct ip6_hbh *)(ip6 + 1);
1416 			hbhlen = (hbh->ip6h_len + 1) << 3;
1417 
1418 			/*
1419 			 * XXX: We copy the whole header even if a
1420 			 * jumbo payload option is included, the option which
1421 			 * is to be removed before returning according to
1422 			 * RFC2292.
1423 			 * Note: this constraint is removed in RFC3542
1424 			 */
1425 			*mp = sbcreatecontrol(hbh, hbhlen,
1426 			    IS2292(inp, IPV6_2292HOPOPTS, IPV6_HOPOPTS),
1427 			    IPPROTO_IPV6, M_NOWAIT);
1428 			if (*mp)
1429 				mp = &(*mp)->m_next;
1430 		}
1431 	}
1432 
1433 	if ((inp->inp_flags & (IN6P_RTHDR | IN6P_DSTOPTS)) != 0) {
1434 		int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);
1435 
1436 		/*
1437 		 * Search for destination options headers or routing
1438 		 * header(s) through the header chain, and stores each
1439 		 * header as ancillary data.
1440 		 * Note that the order of the headers remains in
1441 		 * the chain of ancillary data.
1442 		 */
1443 		while (1) {	/* is explicit loop prevention necessary? */
1444 			struct ip6_ext *ip6e = NULL;
1445 			u_int elen;
1446 
1447 			/*
1448 			 * if it is not an extension header, don't try to
1449 			 * pull it from the chain.
1450 			 */
1451 			switch (nxt) {
1452 			case IPPROTO_DSTOPTS:
1453 			case IPPROTO_ROUTING:
1454 			case IPPROTO_HOPOPTS:
1455 			case IPPROTO_AH: /* is it possible? */
1456 				break;
1457 			default:
1458 				goto loopend;
1459 			}
1460 
1461 			if (off + sizeof(*ip6e) > m->m_len)
1462 				goto loopend;
1463 			ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
1464 			if (nxt == IPPROTO_AH)
1465 				elen = (ip6e->ip6e_len + 2) << 2;
1466 			else
1467 				elen = (ip6e->ip6e_len + 1) << 3;
1468 			if (off + elen > m->m_len)
1469 				goto loopend;
1470 
1471 			switch (nxt) {
1472 			case IPPROTO_DSTOPTS:
1473 				if (!(inp->inp_flags & IN6P_DSTOPTS))
1474 					break;
1475 
1476 				*mp = sbcreatecontrol(ip6e, elen,
1477 				    IS2292(inp, IPV6_2292DSTOPTS, IPV6_DSTOPTS),
1478 				    IPPROTO_IPV6, M_NOWAIT);
1479 				if (*mp)
1480 					mp = &(*mp)->m_next;
1481 				break;
1482 			case IPPROTO_ROUTING:
1483 				if (!(inp->inp_flags & IN6P_RTHDR))
1484 					break;
1485 
1486 				*mp = sbcreatecontrol(ip6e, elen,
1487 				    IS2292(inp, IPV6_2292RTHDR, IPV6_RTHDR),
1488 				    IPPROTO_IPV6, M_NOWAIT);
1489 				if (*mp)
1490 					mp = &(*mp)->m_next;
1491 				break;
1492 			case IPPROTO_HOPOPTS:
1493 			case IPPROTO_AH: /* is it possible? */
1494 				break;
1495 
1496 			default:
1497 				/*
1498 				 * other cases have been filtered in the above.
1499 				 * none will visit this case.  here we supply
1500 				 * the code just in case (nxt overwritten or
1501 				 * other cases).
1502 				 */
1503 				goto loopend;
1504 			}
1505 
1506 			/* proceed with the next header. */
1507 			off += elen;
1508 			nxt = ip6e->ip6e_nxt;
1509 			ip6e = NULL;
1510 		}
1511 	  loopend:
1512 		;
1513 	}
1514 
1515 	if (inp->inp_flags2 & INP_RECVFLOWID) {
1516 		uint32_t flowid, flow_type;
1517 
1518 		flowid = m->m_pkthdr.flowid;
1519 		flow_type = M_HASHTYPE_GET(m);
1520 
1521 		/*
1522 		 * XXX should handle the failure of one or the
1523 		 * other - don't populate both?
1524 		 */
1525 		*mp = sbcreatecontrol(&flowid, sizeof(uint32_t), IPV6_FLOWID,
1526 		    IPPROTO_IPV6, M_NOWAIT);
1527 		if (*mp)
1528 			mp = &(*mp)->m_next;
1529 		*mp = sbcreatecontrol(&flow_type, sizeof(uint32_t),
1530 		    IPV6_FLOWTYPE, IPPROTO_IPV6, M_NOWAIT);
1531 		if (*mp)
1532 			mp = &(*mp)->m_next;
1533 	}
1534 
1535 #ifdef	RSS
1536 	if (inp->inp_flags2 & INP_RECVRSSBUCKETID) {
1537 		uint32_t flowid, flow_type;
1538 		uint32_t rss_bucketid;
1539 
1540 		flowid = m->m_pkthdr.flowid;
1541 		flow_type = M_HASHTYPE_GET(m);
1542 
1543 		if (rss_hash2bucket(flowid, flow_type, &rss_bucketid) == 0) {
1544 			*mp = sbcreatecontrol(&rss_bucketid, sizeof(uint32_t),
1545 			    IPV6_RSSBUCKETID, IPPROTO_IPV6, M_NOWAIT);
1546 			if (*mp)
1547 				mp = &(*mp)->m_next;
1548 		}
1549 	}
1550 #endif
1551 
1552 }
1553 #undef IS2292
1554 
1555 void
1556 ip6_notify_pmtu(struct inpcb *inp, struct sockaddr_in6 *dst, u_int32_t mtu)
1557 {
1558 	struct socket *so;
1559 	struct mbuf *m_mtu;
1560 	struct ip6_mtuinfo mtuctl;
1561 
1562 	KASSERT(inp != NULL, ("%s: inp == NULL", __func__));
1563 	/*
1564 	 * Notify the error by sending IPV6_PATHMTU ancillary data if
1565 	 * application wanted to know the MTU value.
1566 	 * NOTE: we notify disconnected sockets, because some udp
1567 	 * applications keep sending sockets disconnected.
1568 	 * NOTE: our implementation doesn't notify connected sockets that has
1569 	 * foreign address that is different than given destination addresses
1570 	 * (this is permitted by RFC 3542).
1571 	 */
1572 	if ((inp->inp_flags & IN6P_MTU) == 0 || (
1573 	    !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr) &&
1574 	    !IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &dst->sin6_addr)))
1575 		return;
1576 
1577 	mtuctl.ip6m_mtu = mtu;
1578 	mtuctl.ip6m_addr = *dst;
1579 	if (sa6_recoverscope(&mtuctl.ip6m_addr))
1580 		return;
1581 
1582 	if ((m_mtu = sbcreatecontrol(&mtuctl, sizeof(mtuctl), IPV6_PATHMTU,
1583 	    IPPROTO_IPV6, M_NOWAIT)) == NULL)
1584 		return;
1585 
1586 	so =  inp->inp_socket;
1587 	if (sbappendaddr(&so->so_rcv, (struct sockaddr *)dst, NULL, m_mtu)
1588 	    == 0) {
1589 		soroverflow(so);
1590 		m_freem(m_mtu);
1591 		/* XXX: should count statistics */
1592 	} else
1593 		sorwakeup(so);
1594 }
1595 
1596 /*
1597  * Get pointer to the previous header followed by the header
1598  * currently processed.
1599  */
1600 int
1601 ip6_get_prevhdr(const struct mbuf *m, int off)
1602 {
1603 	struct ip6_ext ip6e;
1604 	struct ip6_hdr *ip6;
1605 	int len, nlen, nxt;
1606 
1607 	if (off == sizeof(struct ip6_hdr))
1608 		return (offsetof(struct ip6_hdr, ip6_nxt));
1609 	if (off < sizeof(struct ip6_hdr))
1610 		panic("%s: off < sizeof(struct ip6_hdr)", __func__);
1611 
1612 	ip6 = mtod(m, struct ip6_hdr *);
1613 	nxt = ip6->ip6_nxt;
1614 	len = sizeof(struct ip6_hdr);
1615 	nlen = 0;
1616 	while (len < off) {
1617 		m_copydata(m, len, sizeof(ip6e), (caddr_t)&ip6e);
1618 		switch (nxt) {
1619 		case IPPROTO_FRAGMENT:
1620 			nlen = sizeof(struct ip6_frag);
1621 			break;
1622 		case IPPROTO_AH:
1623 			nlen = (ip6e.ip6e_len + 2) << 2;
1624 			break;
1625 		default:
1626 			nlen = (ip6e.ip6e_len + 1) << 3;
1627 		}
1628 		len += nlen;
1629 		nxt = ip6e.ip6e_nxt;
1630 	}
1631 	return (len - nlen);
1632 }
1633 
1634 /*
1635  * get next header offset.  m will be retained.
1636  */
1637 int
1638 ip6_nexthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1639 {
1640 	struct ip6_hdr ip6;
1641 	struct ip6_ext ip6e;
1642 	struct ip6_frag fh;
1643 
1644 	/* just in case */
1645 	if (m == NULL)
1646 		panic("ip6_nexthdr: m == NULL");
1647 	if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
1648 		return -1;
1649 
1650 	switch (proto) {
1651 	case IPPROTO_IPV6:
1652 		if (m->m_pkthdr.len < off + sizeof(ip6))
1653 			return -1;
1654 		m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
1655 		if (nxtp)
1656 			*nxtp = ip6.ip6_nxt;
1657 		off += sizeof(ip6);
1658 		return off;
1659 
1660 	case IPPROTO_FRAGMENT:
1661 		/*
1662 		 * terminate parsing if it is not the first fragment,
1663 		 * it does not make sense to parse through it.
1664 		 */
1665 		if (m->m_pkthdr.len < off + sizeof(fh))
1666 			return -1;
1667 		m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
1668 		/* IP6F_OFF_MASK = 0xfff8(BigEndian), 0xf8ff(LittleEndian) */
1669 		if (fh.ip6f_offlg & IP6F_OFF_MASK)
1670 			return -1;
1671 		if (nxtp)
1672 			*nxtp = fh.ip6f_nxt;
1673 		off += sizeof(struct ip6_frag);
1674 		return off;
1675 
1676 	case IPPROTO_AH:
1677 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1678 			return -1;
1679 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1680 		if (nxtp)
1681 			*nxtp = ip6e.ip6e_nxt;
1682 		off += (ip6e.ip6e_len + 2) << 2;
1683 		return off;
1684 
1685 	case IPPROTO_HOPOPTS:
1686 	case IPPROTO_ROUTING:
1687 	case IPPROTO_DSTOPTS:
1688 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1689 			return -1;
1690 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1691 		if (nxtp)
1692 			*nxtp = ip6e.ip6e_nxt;
1693 		off += (ip6e.ip6e_len + 1) << 3;
1694 		return off;
1695 
1696 	case IPPROTO_NONE:
1697 	case IPPROTO_ESP:
1698 	case IPPROTO_IPCOMP:
1699 		/* give up */
1700 		return -1;
1701 
1702 	default:
1703 		return -1;
1704 	}
1705 
1706 	/* NOTREACHED */
1707 }
1708 
1709 /*
1710  * get offset for the last header in the chain.  m will be kept untainted.
1711  */
1712 int
1713 ip6_lasthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1714 {
1715 	int newoff;
1716 	int nxt;
1717 
1718 	if (!nxtp) {
1719 		nxt = -1;
1720 		nxtp = &nxt;
1721 	}
1722 	while (1) {
1723 		newoff = ip6_nexthdr(m, off, proto, nxtp);
1724 		if (newoff < 0)
1725 			return off;
1726 		else if (newoff < off)
1727 			return -1;	/* invalid */
1728 		else if (newoff == off)
1729 			return newoff;
1730 
1731 		off = newoff;
1732 		proto = *nxtp;
1733 	}
1734 }
1735