xref: /src/sys/netinet6/ip6_input.c (revision 56dddebc55494fdf75eeb914cc9e345d0d762f8c)
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 "opt_inet.h"
64 #include "opt_inet6.h"
65 #include "opt_ipsec.h"
66 #include "opt_route.h"
67 #include "opt_rss.h"
68 #include "opt_sctp.h"
69 
70 #include <sys/param.h>
71 #include <sys/systm.h>
72 #include <sys/hhook.h>
73 #include <sys/malloc.h>
74 #include <sys/mbuf.h>
75 #include <sys/proc.h>
76 #include <sys/domain.h>
77 #include <sys/protosw.h>
78 #include <sys/sdt.h>
79 #include <sys/socket.h>
80 #include <sys/socketvar.h>
81 #include <sys/errno.h>
82 #include <sys/time.h>
83 #include <sys/kernel.h>
84 #include <sys/lock.h>
85 #include <sys/rmlock.h>
86 #include <sys/syslog.h>
87 #include <sys/sysctl.h>
88 #include <sys/eventhandler.h>
89 
90 #include <net/if.h>
91 #include <net/if_var.h>
92 #include <net/if_types.h>
93 #include <net/if_private.h>
94 #include <net/if_dl.h>
95 #include <net/route.h>
96 #include <net/netisr.h>
97 #include <net/rss_config.h>
98 #include <net/pfil.h>
99 #include <net/vnet.h>
100 
101 #include <netinet/in.h>
102 #include <netinet/in_kdtrace.h>
103 #include <netinet/ip_var.h>
104 #include <netinet/in_systm.h>
105 #include <net/if_llatbl.h>
106 #ifdef INET
107 #include <netinet/ip.h>
108 #include <netinet/ip_icmp.h>
109 #endif /* INET */
110 #include <netinet/ip6.h>
111 #include <netinet6/in6_var.h>
112 #include <netinet6/ip6_var.h>
113 #include <netinet/ip_encap.h>
114 #include <netinet/in_pcb.h>
115 #include <netinet/icmp6.h>
116 #include <netinet6/scope6_var.h>
117 #include <netinet6/in6_ifattach.h>
118 #include <netinet6/mld6_var.h>
119 #include <netinet6/nd6.h>
120 #include <netinet6/in6_rss.h>
121 #include <netinet6/ip6_mroute.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
sysctl_netinet6_intr_queue_maxlen(SYSCTL_HANDLER_ARGS)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 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, temp_max_desync_factor,
177     CTLFLAG_RD | CTLFLAG_VNET,
178     &VNET_NAME(ip6_temp_max_desync_factor), 0,
179     "RFC 8981 max desync factor");
180 
181 #ifdef RSS
182 static struct netisr_handler ip6_direct_nh = {
183 	.nh_name = "ip6_direct",
184 	.nh_handler = ip6_direct_input,
185 	.nh_proto = NETISR_IPV6_DIRECT,
186 	.nh_m2cpuid = rss_soft_m2cpuid_v6,
187 	.nh_policy = NETISR_POLICY_CPU,
188 	.nh_dispatch = NETISR_DISPATCH_HYBRID,
189 };
190 
191 static int
sysctl_netinet6_intr_direct_queue_maxlen(SYSCTL_HANDLER_ARGS)192 sysctl_netinet6_intr_direct_queue_maxlen(SYSCTL_HANDLER_ARGS)
193 {
194 	int error, qlimit;
195 
196 	netisr_getqlimit(&ip6_direct_nh, &qlimit);
197 	error = sysctl_handle_int(oidp, &qlimit, 0, req);
198 	if (error || !req->newptr)
199 		return (error);
200 	if (qlimit < 1)
201 		return (EINVAL);
202 	return (netisr_setqlimit(&ip6_direct_nh, qlimit));
203 }
204 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_INTRDQMAXLEN, intr_direct_queue_maxlen,
205     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
206     0, 0, sysctl_netinet6_intr_direct_queue_maxlen, "I",
207     "Maximum size of the IPv6 direct input queue");
208 
209 #endif
210 
211 VNET_DEFINE(pfil_head_t, inet6_pfil_head);
212 VNET_DEFINE(pfil_head_t, inet6_local_pfil_head);
213 
214 VNET_PCPUSTAT_DEFINE(struct ip6stat, ip6stat);
215 VNET_PCPUSTAT_SYSINIT(ip6stat);
216 #ifdef VIMAGE
217 VNET_PCPUSTAT_SYSUNINIT(ip6stat);
218 #endif /* VIMAGE */
219 
220 struct rmlock in6_ifaddr_lock;
221 RM_SYSINIT(in6_ifaddr_lock, &in6_ifaddr_lock, "in6_ifaddr_lock");
222 
223 static int ip6_hopopts_input(u_int32_t *, struct mbuf **, int *);
224 
225 /*
226  * IP6 initialization: fill in IP6 protocol switch table.
227  * All protocols not implemented in kernel go to raw IP6 protocol handler.
228  */
229 static void
ip6_vnet_init(void * arg __unused)230 ip6_vnet_init(void *arg __unused)
231 {
232 	struct pfil_head_args args;
233 
234 	TUNABLE_INT_FETCH("net.inet6.ip6.auto_linklocal",
235 	    &V_ip6_auto_linklocal);
236 	TUNABLE_INT_FETCH("net.inet6.ip6.accept_rtadv", &V_ip6_accept_rtadv);
237 	TUNABLE_INT_FETCH("net.inet6.ip6.no_radr", &V_ip6_no_radr);
238 	TUNABLE_BOOL_FETCH("net.inet6.ip6.use_stableaddr", &V_ip6_use_stableaddr);
239 
240 	CK_STAILQ_INIT(&V_in6_ifaddrhead);
241 	V_in6_ifaddrhashtbl = hashinit(IN6ADDR_NHASH, M_IFADDR,
242 	    &V_in6_ifaddrhmask);
243 
244 	/* Initialize packet filter hooks. */
245 	args.pa_version = PFIL_VERSION;
246 	args.pa_flags = PFIL_IN | PFIL_OUT;
247 	args.pa_type = PFIL_TYPE_IP6;
248 	args.pa_headname = PFIL_INET6_NAME;
249 	V_inet6_pfil_head = pfil_head_register(&args);
250 
251 	args.pa_flags = PFIL_OUT;
252 	args.pa_headname = PFIL_INET6_LOCAL_NAME;
253 	V_inet6_local_pfil_head = pfil_head_register(&args);
254 
255 	if (hhook_head_register(HHOOK_TYPE_IPSEC_IN, AF_INET6,
256 	    &V_ipsec_hhh_in[HHOOK_IPSEC_INET6],
257 	    HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
258 		printf("%s: WARNING: unable to register input helper hook\n",
259 		    __func__);
260 	if (hhook_head_register(HHOOK_TYPE_IPSEC_OUT, AF_INET6,
261 	    &V_ipsec_hhh_out[HHOOK_IPSEC_INET6],
262 	    HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
263 		printf("%s: WARNING: unable to register output helper hook\n",
264 		    __func__);
265 
266 	scope6_init();
267 	addrsel_policy_init();
268 	nd6_init();
269 	frag6_init();
270 
271 	V_ip6_temp_max_desync_factor = TEMP_MAX_DESYNC_FACTOR_BASE +
272 	    (V_ip6_temp_preferred_lifetime >> 2) +
273 	    (V_ip6_temp_preferred_lifetime >> 3);
274 	V_ip6_desync_factor = arc4random() % V_ip6_temp_max_desync_factor;
275 
276 	/* Skip global initialization stuff for non-default instances. */
277 #ifdef VIMAGE
278 	netisr_register_vnet(&ip6_nh);
279 #ifdef RSS
280 	netisr_register_vnet(&ip6_direct_nh);
281 #endif
282 #endif
283 }
284 VNET_SYSINIT(ip6_vnet_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH,
285     ip6_vnet_init, NULL);
286 
287 static void
ip6_init(void * arg __unused)288 ip6_init(void *arg __unused)
289 {
290 	struct ifnet *ifp;
291 
292 	/*
293 	 * Register statically those protocols that are unlikely to ever go
294 	 * dynamic.
295 	 */
296 	IP6PROTO_REGISTER(IPPROTO_ICMPV6, icmp6_input, rip6_ctlinput);
297 	IP6PROTO_REGISTER(IPPROTO_DSTOPTS, dest6_input, NULL);
298 	IP6PROTO_REGISTER(IPPROTO_ROUTING, route6_input, NULL);
299 	IP6PROTO_REGISTER(IPPROTO_FRAGMENT, frag6_input, NULL);
300 	IP6PROTO_REGISTER(IPPROTO_IPV4, encap6_input, NULL);
301 	IP6PROTO_REGISTER(IPPROTO_IPV6, encap6_input, NULL);
302 	IP6PROTO_REGISTER(IPPROTO_ETHERIP, encap6_input, NULL);
303 	IP6PROTO_REGISTER(IPPROTO_GRE, encap6_input, NULL);
304 	IP6PROTO_REGISTER(IPPROTO_PIM, encap6_input, NULL);
305 #ifdef SCTP	/* XXX: has a loadable & static version */
306 	IP6PROTO_REGISTER(IPPROTO_SCTP, sctp6_input, sctp6_ctlinput);
307 #endif
308 
309 	EVENTHANDLER_REGISTER(vm_lowmem, frag6_drain, NULL, LOWMEM_PRI_DEFAULT);
310 	EVENTHANDLER_REGISTER(mbuf_lowmem, frag6_drain, NULL,
311 	    LOWMEM_PRI_DEFAULT);
312 
313 	netisr_register(&ip6_nh);
314 #ifdef RSS
315 	netisr_register(&ip6_direct_nh);
316 #endif
317 	/*
318          * XXXGL: we use SYSINIT() here, but go over V_ifnet.  See comment
319 	 * in sys/netinet/ip_input.c:ip_init().
320          */
321         CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link)
322                 in6_ifarrival(NULL, ifp);
323 }
324 SYSINIT(ip6_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, ip6_init, NULL);
325 
326 int
ip6proto_register(uint8_t proto,ip6proto_input_t input,ip6proto_ctlinput_t ctl)327 ip6proto_register(uint8_t proto, ip6proto_input_t input,
328     ip6proto_ctlinput_t ctl)
329 {
330 
331 	MPASS(proto > 0);
332 
333 	if (ip6_protox[proto] == rip6_input) {
334 		ip6_protox[proto] = input;
335 		ip6_ctlprotox[proto] = ctl;
336 		return (0);
337 	} else
338 		return (EEXIST);
339 }
340 
341 int
ip6proto_unregister(uint8_t proto)342 ip6proto_unregister(uint8_t proto)
343 {
344 
345 	MPASS(proto > 0);
346 
347 	if (ip6_protox[proto] != rip6_input) {
348 		ip6_protox[proto] = rip6_input;
349 		ip6_ctlprotox[proto] = rip6_ctlinput;
350 		return (0);
351 	} else
352 		return (ENOENT);
353 }
354 
355 #ifdef VIMAGE
356 static void
ip6_destroy(void * unused __unused)357 ip6_destroy(void *unused __unused)
358 {
359 	struct ifaddr *ifa, *nifa;
360 	struct ifnet *ifp;
361 	int error;
362 
363 #ifdef RSS
364 	netisr_unregister_vnet(&ip6_direct_nh);
365 #endif
366 	netisr_unregister_vnet(&ip6_nh);
367 
368 	pfil_head_unregister(V_inet6_pfil_head);
369 	error = hhook_head_deregister(V_ipsec_hhh_in[HHOOK_IPSEC_INET6]);
370 	if (error != 0) {
371 		printf("%s: WARNING: unable to deregister input helper hook "
372 		    "type HHOOK_TYPE_IPSEC_IN, id HHOOK_IPSEC_INET6: "
373 		    "error %d returned\n", __func__, error);
374 	}
375 	error = hhook_head_deregister(V_ipsec_hhh_out[HHOOK_IPSEC_INET6]);
376 	if (error != 0) {
377 		printf("%s: WARNING: unable to deregister output helper hook "
378 		    "type HHOOK_TYPE_IPSEC_OUT, id HHOOK_IPSEC_INET6: "
379 		    "error %d returned\n", __func__, error);
380 	}
381 
382 	/* Cleanup addresses. */
383 	IFNET_RLOCK();
384 	CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
385 		/* Cannot lock here - lock recursion. */
386 		/* IF_ADDR_LOCK(ifp); */
387 		CK_STAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, nifa) {
388 			if (ifa->ifa_addr->sa_family != AF_INET6)
389 				continue;
390 			in6_purgeaddr(ifa);
391 		}
392 		/* IF_ADDR_UNLOCK(ifp); */
393 		in6_ifdetach_destroy(ifp);
394 	}
395 	IFNET_RUNLOCK();
396 
397 	/* Make sure any routes are gone as well. */
398 	rib_flush_routes_family(AF_INET6);
399 
400 	frag6_destroy();
401 	nd6_destroy();
402 	in6_ifattach_destroy();
403 
404 	hashdestroy(V_in6_ifaddrhashtbl, M_IFADDR, V_in6_ifaddrhmask);
405 }
406 
407 VNET_SYSUNINIT(inet6, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, ip6_destroy, NULL);
408 #endif
409 
410 static int
ip6_input_hbh(struct mbuf ** mp,uint32_t * rtalert,int * off,int * nxt,int * ours)411 ip6_input_hbh(struct mbuf **mp, uint32_t *rtalert, int *off,
412     int *nxt, int *ours)
413 {
414 	struct mbuf *m;
415 	struct ip6_hdr *ip6;
416 	struct ip6_hbh *hbh;
417 
418 	if (ip6_hopopts_input(rtalert, mp, off)) {
419 #if 0	/*touches NULL pointer*/
420 		in6_ifstat_inc((*mp)->m_pkthdr.rcvif, ifs6_in_discard);
421 #endif
422 		goto out;	/* m have already been freed */
423 	}
424 
425 	/* adjust pointer */
426 	m = *mp;
427 	ip6 = mtod(m, struct ip6_hdr *);
428 
429 	/*
430 	 * If the payload length field is 0 and the next header field indicates
431 	 * Hop-by-Hop Options header, then a Jumbo Payload option MUST be
432 	 * included. We no not support Jumbo Payloads so report an error.
433 	 */
434 	if (ip6->ip6_plen == 0) {
435 		IP6STAT_INC(ip6s_badoptions);
436 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
437 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
438 		icmp6_error(m, ICMP6_PARAM_PROB,
439 			    ICMP6_PARAMPROB_HEADER,
440 			    (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
441 		goto out;
442 	}
443 	/* ip6_hopopts_input() ensures that mbuf is contiguous */
444 	hbh = (struct ip6_hbh *)(ip6 + 1);
445 	*nxt = hbh->ip6h_nxt;
446 
447 	/*
448 	 * If we are acting as a router and the packet contains a
449 	 * router alert option, see if we know the option value.
450 	 * Currently, we only support the option value for MLD, in which
451 	 * case we should pass the packet to the multicast routing
452 	 * daemon.
453 	 */
454 	if (*rtalert != ~0) {
455 		switch (*rtalert) {
456 		case IP6OPT_RTALERT_MLD:
457 			if (V_ip6_forwarding)
458 				*ours = 1;
459 			break;
460 		default:
461 			/*
462 			 * RFC2711 requires unrecognized values must be
463 			 * silently ignored.
464 			 */
465 			break;
466 		}
467 	}
468 
469 	return (0);
470 
471 out:
472 	return (1);
473 }
474 
475 #ifdef RSS
476 /*
477  * IPv6 direct input routine.
478  *
479  * This is called when reinjecting completed fragments where
480  * all of the previous checking and book-keeping has been done.
481  */
482 void
ip6_direct_input(struct mbuf * m)483 ip6_direct_input(struct mbuf *m)
484 {
485 	int off, nxt;
486 	int nest;
487 	struct m_tag *mtag;
488 	struct ip6_direct_ctx *ip6dc;
489 
490 	mtag = m_tag_locate(m, MTAG_ABI_IPV6, IPV6_TAG_DIRECT, NULL);
491 	KASSERT(mtag != NULL, ("Reinjected packet w/o direct ctx tag!"));
492 
493 	ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
494 	nxt = ip6dc->ip6dc_nxt;
495 	off = ip6dc->ip6dc_off;
496 
497 	nest = 0;
498 
499 	m_tag_delete(m, mtag);
500 
501 	while (nxt != IPPROTO_DONE) {
502 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
503 			IP6STAT_INC(ip6s_toomanyhdr);
504 			goto bad;
505 		}
506 
507 		/*
508 		 * protection against faulty packet - there should be
509 		 * more sanity checks in header chain processing.
510 		 */
511 		if (m->m_pkthdr.len < off) {
512 			IP6STAT_INC(ip6s_tooshort);
513 			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
514 			goto bad;
515 		}
516 
517 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
518 		if (IPSEC_ENABLED(ipv6)) {
519 			if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
520 				return;
521 		}
522 #endif /* IPSEC */
523 
524 		nxt = ip6_protox[nxt](&m, &off, nxt);
525 	}
526 	return;
527 bad:
528 	m_freem(m);
529 }
530 #endif
531 
532 void
ip6_input(struct mbuf * m)533 ip6_input(struct mbuf *m)
534 {
535 	struct in6_addr odst;
536 	struct ip6_hdr *ip6;
537 	struct in6_ifaddr *ia;
538 	struct ifnet *rcvif;
539 	u_int32_t plen;
540 	u_int32_t rtalert = ~0;
541 	int off = sizeof(struct ip6_hdr), nest;
542 	int nxt, ours = 0;
543 	int srcrt = 0;
544 
545 	/*
546 	 * Drop the packet if IPv6 operation is disabled on the interface.
547 	 */
548 	rcvif = m->m_pkthdr.rcvif;
549 	if ((rcvif->if_inet6->nd_flags & ND6_IFF_IFDISABLED))
550 		goto bad;
551 
552 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
553 	/*
554 	 * should the inner packet be considered authentic?
555 	 * see comment in ah4_input().
556 	 * NB: m cannot be NULL when passed to the input routine
557 	 */
558 
559 	m->m_flags &= ~M_AUTHIPHDR;
560 	m->m_flags &= ~M_AUTHIPDGM;
561 
562 #endif /* IPSEC */
563 
564 	if (m->m_flags & M_FASTFWD_OURS) {
565 		/*
566 		 * Firewall changed destination to local.
567 		 */
568 		ip6 = mtod(m, struct ip6_hdr *);
569 		goto passin;
570 	}
571 
572 	/*
573 	 * mbuf statistics
574 	 */
575 	if (m->m_flags & M_EXT) {
576 		if (m->m_next)
577 			IP6STAT_INC(ip6s_mext2m);
578 		else
579 			IP6STAT_INC(ip6s_mext1);
580 	} else {
581 		if (m->m_next) {
582 			struct ifnet *ifp = (m->m_flags & M_LOOP) ? V_loif : rcvif;
583 			int ifindex = ifp->if_index;
584 			if (ifindex >= IP6S_M2MMAX)
585 				ifindex = 0;
586 			IP6STAT_INC2(ip6s_m2m, ifindex);
587 		} else
588 			IP6STAT_INC(ip6s_m1);
589 	}
590 
591 	in6_ifstat_inc(rcvif, ifs6_in_receive);
592 	IP6STAT_INC(ip6s_total);
593 
594 	/*
595 	 * L2 bridge code and some other code can return mbuf chain
596 	 * that does not conform to KAME requirement.  too bad.
597 	 * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
598 	 */
599 	if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
600 		struct mbuf *n;
601 
602 		if (m->m_pkthdr.len > MHLEN)
603 			n = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
604 		else
605 			n = m_gethdr(M_NOWAIT, MT_DATA);
606 		if (n == NULL)
607 			goto bad;
608 
609 		m_move_pkthdr(n, m);
610 		m_copydata(m, 0, n->m_pkthdr.len, mtod(n, caddr_t));
611 		n->m_len = n->m_pkthdr.len;
612 		m_freem(m);
613 		m = n;
614 	}
615 	if (m->m_len < sizeof(struct ip6_hdr)) {
616 		if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
617 			IP6STAT_INC(ip6s_toosmall);
618 			in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
619 			goto bad;
620 		}
621 	}
622 
623 	ip6 = mtod(m, struct ip6_hdr *);
624 	if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
625 		IP6STAT_INC(ip6s_badvers);
626 		in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
627 		goto bad;
628 	}
629 
630 	IP6STAT_INC2(ip6s_nxthist, ip6->ip6_nxt);
631 	IP_PROBE(receive, NULL, NULL, ip6, rcvif, NULL, ip6);
632 
633 	/*
634 	 * Check against address spoofing/corruption.  The unspecified address
635 	 * is checked further below.
636 	 */
637 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) {
638 		/*
639 		 * XXX: "badscope" is not very suitable for a multicast source.
640 		 */
641 		IP6STAT_INC(ip6s_badscope);
642 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
643 		goto bad;
644 	}
645 	if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) &&
646 	    !(m->m_flags & M_LOOP)) {
647 		/*
648 		 * In this case, the packet should come from the loopback
649 		 * interface.  However, we cannot just check the if_flags,
650 		 * because ip6_mloopback() passes the "actual" interface
651 		 * as the outgoing/incoming interface.
652 		 */
653 		IP6STAT_INC(ip6s_badscope);
654 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
655 		goto bad;
656 	}
657 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) &&
658 	    IPV6_ADDR_MC_SCOPE(&ip6->ip6_dst) == 0) {
659 		/*
660 		 * RFC4291 2.7:
661 		 * Nodes must not originate a packet to a multicast address
662 		 * whose scop field contains the reserved value 0; if such
663 		 * a packet is received, it must be silently dropped.
664 		 */
665 		IP6STAT_INC(ip6s_badscope);
666 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
667 		goto bad;
668 	}
669 	/*
670 	 * The following check is not documented in specs.  A malicious
671 	 * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
672 	 * and bypass security checks (act as if it was from 127.0.0.1 by using
673 	 * IPv6 src ::ffff:127.0.0.1).  Be cautious.
674 	 *
675 	 * We have supported IPv6-only kernels for a few years and this issue
676 	 * has not come up.  The world seems to move mostly towards not using
677 	 * v4mapped on the wire, so it makes sense for us to keep rejecting
678 	 * any such packets.
679 	 */
680 	if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
681 	    IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
682 		IP6STAT_INC(ip6s_badscope);
683 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
684 		goto bad;
685 	}
686 	/*
687 	 * Try to forward the packet, but if we fail continue.
688 	 * ip6_tryforward() does not generate redirects, so fall
689 	 * through to normal processing if redirects are required.
690 	 * ip6_tryforward() does inbound and outbound packet firewall
691 	 * processing. If firewall has decided that destination becomes
692 	 * our local address, it sets M_FASTFWD_OURS flag. In this
693 	 * case skip another inbound firewall processing and update
694 	 * ip6 pointer.
695 	 */
696 	if (V_ip6_forwarding != 0 && V_ip6_sendredirects == 0
697 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
698 	    && (!IPSEC_ENABLED(ipv6) ||
699 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_OPERABLE) == 0)
700 #endif
701 	    ) {
702 		if ((m = ip6_tryforward(m)) == NULL)
703 			return;
704 		if (m->m_flags & M_FASTFWD_OURS) {
705 			ip6 = mtod(m, struct ip6_hdr *);
706 			goto passin;
707 		}
708 	}
709 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
710 	/*
711 	 * Bypass packet filtering for packets previously handled by IPsec.
712 	 */
713 	if (IPSEC_ENABLED(ipv6) &&
714 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_BYPASS_FILTER) != 0)
715 			goto passin;
716 #endif
717 	/*
718 	 * Run through list of hooks for input packets.
719 	 *
720 	 * NB: Beware of the destination address changing
721 	 *     (e.g. by NAT rewriting).  When this happens,
722 	 *     tell ip6_forward to do the right thing.
723 	 */
724 
725 	/* Jump over all PFIL processing if hooks are not active. */
726 	if (!PFIL_HOOKED_IN(V_inet6_pfil_head))
727 		goto passin;
728 
729 	odst = ip6->ip6_dst;
730 	if (pfil_mbuf_in(V_inet6_pfil_head, &m, m->m_pkthdr.rcvif,
731 	    NULL) != PFIL_PASS)
732 		return;
733 	ip6 = mtod(m, struct ip6_hdr *);
734 	srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
735 	if ((m->m_flags & (M_IP6_NEXTHOP | M_FASTFWD_OURS)) == M_IP6_NEXTHOP &&
736 	    m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL) {
737 		/*
738 		 * Directly ship the packet on.  This allows forwarding
739 		 * packets originally destined to us to some other directly
740 		 * connected host.
741 		 */
742 		ip6_forward(m, 1);
743 		return;
744 	}
745 
746 passin:
747 	/*
748 	 * The check is deferred to here to give firewalls a chance to block
749 	 * (and log) such packets.  ip6_tryforward() will not process such
750 	 * packets.
751 	 */
752 	if (__predict_false(IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst))) {
753 		IP6STAT_INC(ip6s_badscope);
754 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
755 		goto bad;
756 	}
757 
758 	plen = (uint32_t)ntohs(ip6->ip6_plen);
759 
760 	/*
761 	 * We don't support Jumbograms, reject packets with plen == 0 as early
762 	 * as we can.
763 	 */
764 	if (plen == 0)
765 		goto bad;
766 
767 	/*
768 	 * Disambiguate address scope zones (if there is ambiguity).
769 	 * We first make sure that the original source or destination address
770 	 * is not in our internal form for scoped addresses.  Such addresses
771 	 * are not necessarily invalid spec-wise, but we cannot accept them due
772 	 * to the usage conflict.
773 	 * in6_setscope() then also checks and rejects the cases where src or
774 	 * dst are the loopback address and the receiving interface
775 	 * is not loopback.
776 	 */
777 	if (in6_clearscope(&ip6->ip6_src) || in6_clearscope(&ip6->ip6_dst)) {
778 		IP6STAT_INC(ip6s_badscope); /* XXX */
779 		goto bad;
780 	}
781 	if (in6_setscope(&ip6->ip6_src, rcvif, NULL) ||
782 	    in6_setscope(&ip6->ip6_dst, rcvif, NULL)) {
783 		IP6STAT_INC(ip6s_badscope);
784 		goto bad;
785 	}
786 	if (m->m_flags & M_FASTFWD_OURS) {
787 		m->m_flags &= ~M_FASTFWD_OURS;
788 		ours = 1;
789 		goto hbhcheck;
790 	}
791 	/*
792 	 * Multicast check. Assume packet is for us to avoid
793 	 * prematurely taking locks.
794 	 */
795 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
796 		ours = 1;
797 		in6_ifstat_inc(rcvif, ifs6_in_mcast);
798 		goto hbhcheck;
799 	}
800 	/*
801 	 * Unicast check
802 	 * XXX: For now we keep link-local IPv6 addresses with embedded
803 	 *      scope zone id, therefore we use zero zoneid here.
804 	 */
805 	ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false);
806 	if (ia != NULL) {
807 		if (ia->ia6_flags & IN6_IFF_NOTREADY) {
808 			char ip6bufs[INET6_ADDRSTRLEN];
809 			char ip6bufd[INET6_ADDRSTRLEN];
810 			/* address is not ready, so discard the packet. */
811 			nd6log((LOG_INFO,
812 			    "ip6_input: packet to an unready address %s->%s\n",
813 			    ip6_sprintf(ip6bufs, &ip6->ip6_src),
814 			    ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
815 			goto bad;
816 		}
817 		if (V_ip6_sav && !(m->m_flags & M_LOOP) &&
818 		    __predict_false(in6_localip_fib(&ip6->ip6_src,
819 			    rcvif->if_fib))) {
820 			IP6STAT_INC(ip6s_badscope); /* XXX */
821 			goto bad;
822 		}
823 		/* Count the packet in the ip address stats */
824 		counter_u64_add(ia->ia_ifa.ifa_ipackets, 1);
825 		counter_u64_add(ia->ia_ifa.ifa_ibytes, m->m_pkthdr.len);
826 		ours = 1;
827 		goto hbhcheck;
828 	}
829 
830 	/*
831 	 * Now there is no reason to process the packet if it's not our own
832 	 * and we're not a router.
833 	 */
834 	if (!V_ip6_forwarding) {
835 		IP6STAT_INC(ip6s_cantforward);
836 		goto bad;
837 	}
838 
839   hbhcheck:
840 	/*
841 	 * Process Hop-by-Hop options header if it's contained.
842 	 * m may be modified in ip6_hopopts_input().
843 	 */
844 	if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
845 		if (ip6_input_hbh(&m, &rtalert, &off, &nxt, &ours) != 0)
846 			return;
847 	} else
848 		nxt = ip6->ip6_nxt;
849 
850 	/*
851 	 * Use mbuf flags to propagate Router Alert option to
852 	 * ICMPv6 layer, as hop-by-hop options have been stripped.
853 	 */
854 	if (rtalert != ~0)
855 		m->m_flags |= M_RTALERT_MLD;
856 
857 	/*
858 	 * Check that the amount of data in the buffers
859 	 * is as at least much as the IPv6 header would have us expect.
860 	 * Trim mbufs if longer than we expect.
861 	 * Drop packet if shorter than we expect.
862 	 */
863 	if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
864 		IP6STAT_INC(ip6s_tooshort);
865 		in6_ifstat_inc(rcvif, ifs6_in_truncated);
866 		goto bad;
867 	}
868 	if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
869 		if (m->m_len == m->m_pkthdr.len) {
870 			m->m_len = sizeof(struct ip6_hdr) + plen;
871 			m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
872 		} else
873 			m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
874 	}
875 
876 	/*
877 	 * Forward if desirable.
878 	 */
879 	if (V_ip6_mrouting_enabled &&
880 	    IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
881 		/*
882 		 * If we are acting as a multicast router, all
883 		 * incoming multicast packets are passed to the
884 		 * kernel-level multicast forwarding function.
885 		 * The packet is returned (relatively) intact; if
886 		 * ip6_mforward() returns a non-zero value, the packet
887 		 * must be discarded, else it may be accepted below.
888 		 *
889 		 * XXX TODO: Check hlim and multicast scope here to avoid
890 		 * unnecessarily calling into ip6_mforward().
891 		 */
892 		if (ip6_mforward && ip6_mforward(ip6, rcvif, m)) {
893 			IP6STAT_INC(ip6s_cantforward);
894 			goto bad;
895 		}
896 	} else if (!ours) {
897 		ip6_forward(m, srcrt);
898 		return;
899 	}
900 
901 	/*
902 	 * We are going to ship the packet to the local protocol stack. Call the
903 	 * filter again for this 'output' action, allowing redirect-like rules
904 	 * to adjust the source address.
905 	 */
906 	if (PFIL_HOOKED_OUT(V_inet6_local_pfil_head)) {
907 		if (pfil_mbuf_out(V_inet6_local_pfil_head, &m, V_loif, NULL) !=
908 		    PFIL_PASS)
909 			return;
910 		ip6 = mtod(m, struct ip6_hdr *);
911 	}
912 
913 	/*
914 	 * Tell launch routine the next header
915 	 */
916 	IP6STAT_INC(ip6s_delivered);
917 	in6_ifstat_inc(rcvif, ifs6_in_deliver);
918 	nest = 0;
919 
920 	while (nxt != IPPROTO_DONE) {
921 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
922 			IP6STAT_INC(ip6s_toomanyhdr);
923 			goto bad;
924 		}
925 
926 		/*
927 		 * protection against faulty packet - there should be
928 		 * more sanity checks in header chain processing.
929 		 */
930 		if (m->m_pkthdr.len < off) {
931 			IP6STAT_INC(ip6s_tooshort);
932 			in6_ifstat_inc(rcvif, ifs6_in_truncated);
933 			goto bad;
934 		}
935 
936 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
937 		if (IPSEC_ENABLED(ipv6)) {
938 			if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
939 				return;
940 		}
941 #endif /* IPSEC */
942 
943 		nxt = ip6_protox[nxt](&m, &off, nxt);
944 	}
945 	return;
946 bad:
947 	in6_ifstat_inc(rcvif, ifs6_in_discard);
948 	if (m != NULL)
949 		m_freem(m);
950 }
951 
952 /*
953  * Hop-by-Hop options header processing. If a valid jumbo payload option is
954  * included report an error.
955  *
956  * rtalertp - XXX: should be stored more smart way
957  */
958 static int
ip6_hopopts_input(u_int32_t * rtalertp,struct mbuf ** mp,int * offp)959 ip6_hopopts_input(u_int32_t *rtalertp, struct mbuf **mp, int *offp)
960 {
961 	struct mbuf *m = *mp;
962 	int off = *offp, hbhlen;
963 	struct ip6_hbh *hbh;
964 
965 	/* validation of the length of the header */
966 	if (m->m_len < off + sizeof(*hbh)) {
967 		m = m_pullup(m, off + sizeof(*hbh));
968 		if (m == NULL) {
969 			IP6STAT_INC(ip6s_exthdrtoolong);
970 			*mp = NULL;
971 			return (-1);
972 		}
973 	}
974 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
975 	hbhlen = (hbh->ip6h_len + 1) << 3;
976 
977 	if (m->m_len < off + hbhlen) {
978 		m = m_pullup(m, off + hbhlen);
979 		if (m == NULL) {
980 			IP6STAT_INC(ip6s_exthdrtoolong);
981 			*mp = NULL;
982 			return (-1);
983 		}
984 	}
985 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
986 	off += hbhlen;
987 	hbhlen -= sizeof(struct ip6_hbh);
988 	if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
989 				hbhlen, rtalertp) < 0) {
990 		*mp = NULL;
991 		return (-1);
992 	}
993 
994 	*offp = off;
995 	*mp = m;
996 	return (0);
997 }
998 
999 /*
1000  * Search header for all Hop-by-hop options and process each option.
1001  * This function is separate from ip6_hopopts_input() in order to
1002  * handle a case where the sending node itself process its hop-by-hop
1003  * options header. In such a case, the function is called from ip6_output().
1004  *
1005  * The function assumes that hbh header is located right after the IPv6 header
1006  * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
1007  * opthead + hbhlen is located in contiguous memory region.
1008  */
1009 int
ip6_process_hopopts(struct mbuf * m,u_int8_t * opthead,int hbhlen,u_int32_t * rtalertp)1010 ip6_process_hopopts(struct mbuf *m, u_int8_t *opthead, int hbhlen,
1011     u_int32_t *rtalertp)
1012 {
1013 	int optlen = 0;
1014 	u_int8_t *opt = opthead;
1015 	u_int16_t rtalert_val;
1016 	const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);
1017 
1018 	for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
1019 		switch (*opt) {
1020 		case IP6OPT_PAD1:
1021 			optlen = 1;
1022 			break;
1023 		case IP6OPT_PADN:
1024 			if (hbhlen < IP6OPT_MINLEN) {
1025 				IP6STAT_INC(ip6s_toosmall);
1026 				goto bad;
1027 			}
1028 			optlen = *(opt + 1) + 2;
1029 			break;
1030 		case IP6OPT_ROUTER_ALERT:
1031 			/* XXX may need check for alignment */
1032 			if (hbhlen < IP6OPT_RTALERT_LEN) {
1033 				IP6STAT_INC(ip6s_toosmall);
1034 				goto bad;
1035 			}
1036 			if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
1037 				/* XXX stat */
1038 				icmp6_error(m, ICMP6_PARAM_PROB,
1039 				    ICMP6_PARAMPROB_HEADER,
1040 				    erroff + opt + 1 - opthead);
1041 				return (-1);
1042 			}
1043 			optlen = IP6OPT_RTALERT_LEN;
1044 			bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
1045 			*rtalertp = ntohs(rtalert_val);
1046 			break;
1047 		case IP6OPT_JUMBO:
1048 			/* We do not support the Jumbo Payload option. */
1049 			goto bad;
1050 		default:		/* unknown option */
1051 			if (hbhlen < IP6OPT_MINLEN) {
1052 				IP6STAT_INC(ip6s_toosmall);
1053 				goto bad;
1054 			}
1055 			optlen = ip6_unknown_opt(opt, m,
1056 			    erroff + opt - opthead);
1057 			if (optlen == -1)
1058 				return (-1);
1059 			optlen += 2;
1060 			break;
1061 		}
1062 	}
1063 
1064 	return (0);
1065 
1066   bad:
1067 	m_freem(m);
1068 	return (-1);
1069 }
1070 
1071 /*
1072  * Unknown option processing.
1073  * The third argument `off' is the offset from the IPv6 header to the option,
1074  * which is necessary if the IPv6 header the and option header and IPv6 header
1075  * is not contiguous in order to return an ICMPv6 error.
1076  */
1077 int
ip6_unknown_opt(u_int8_t * optp,struct mbuf * m,int off)1078 ip6_unknown_opt(u_int8_t *optp, struct mbuf *m, int off)
1079 {
1080 	struct ip6_hdr *ip6;
1081 
1082 	switch (IP6OPT_TYPE(*optp)) {
1083 	case IP6OPT_TYPE_SKIP: /* ignore the option */
1084 		return ((int)*(optp + 1));
1085 	case IP6OPT_TYPE_DISCARD:	/* silently discard */
1086 		m_freem(m);
1087 		return (-1);
1088 	case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
1089 		IP6STAT_INC(ip6s_badoptions);
1090 		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
1091 		return (-1);
1092 	case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
1093 		IP6STAT_INC(ip6s_badoptions);
1094 		ip6 = mtod(m, struct ip6_hdr *);
1095 		if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
1096 		    (m->m_flags & (M_BCAST|M_MCAST)))
1097 			m_freem(m);
1098 		else
1099 			icmp6_error(m, ICMP6_PARAM_PROB,
1100 				    ICMP6_PARAMPROB_OPTION, off);
1101 		return (-1);
1102 	}
1103 
1104 	m_freem(m);		/* XXX: NOTREACHED */
1105 	return (-1);
1106 }
1107 
1108 /*
1109  * Create the "control" list for this pcb.
1110  * These functions will not modify mbuf chain at all.
1111  *
1112  * The routine will be called from upper layer handlers like tcp6_input().
1113  * Thus the routine assumes that the caller (tcp6_input) have already
1114  * called m_pullup() and all the extension headers are located in the
1115  * very first mbuf on the mbuf chain.
1116  *
1117  * ip6_savecontrol_v4 will handle those options that are possible to be
1118  * set on a v4-mapped socket.
1119  * ip6_savecontrol will directly call ip6_savecontrol_v4 to handle those
1120  * options and handle the v6-only ones itself.
1121  */
1122 struct mbuf **
ip6_savecontrol_v4(struct inpcb * inp,struct mbuf * m,struct mbuf ** mp,int * v4only)1123 ip6_savecontrol_v4(struct inpcb *inp, struct mbuf *m, struct mbuf **mp,
1124     int *v4only)
1125 {
1126 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
1127 
1128 #if defined(SO_TIMESTAMP) && defined(SO_BINTIME)
1129 	if ((inp->inp_socket->so_options & (SO_TIMESTAMP | SO_BINTIME)) != 0) {
1130 		union {
1131 			struct timeval tv;
1132 			struct bintime bt;
1133 			struct timespec ts;
1134 		} t;
1135 		struct bintime boottimebin, bt1;
1136 		struct timespec ts1;
1137 		int ts_clock;
1138 		bool stamped;
1139 
1140 		ts_clock = inp->inp_socket->so_ts_clock;
1141 		stamped = false;
1142 
1143 		/*
1144 		 * Handle BINTIME first. We create the same output options
1145 		 * for both SO_BINTIME and the case where SO_TIMESTAMP is
1146 		 * set with the timestamp clock set to SO_TS_BINTIME.
1147 		 */
1148 		if ((inp->inp_socket->so_options & SO_BINTIME) != 0 ||
1149 		    ts_clock == SO_TS_BINTIME) {
1150 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1151 			    M_TSTMP)) {
1152 				mbuf_tstmp2timespec(m, &ts1);
1153 				timespec2bintime(&ts1, &t.bt);
1154 				getboottimebin(&boottimebin);
1155 				bintime_add(&t.bt, &boottimebin);
1156 			} else {
1157 				bintime(&t.bt);
1158 			}
1159 			*mp = sbcreatecontrol(&t.bt, sizeof(t.bt), SCM_BINTIME,
1160 			    SOL_SOCKET, M_NOWAIT);
1161 			if (*mp != NULL) {
1162 				mp = &(*mp)->m_next;
1163 				stamped = true;
1164 			}
1165 
1166 			/*
1167 			 * Suppress other timestamps if SO_TIMESTAMP is not
1168 			 * set.
1169 			 */
1170 			if ((inp->inp_socket->so_options & SO_TIMESTAMP) == 0)
1171 				ts_clock = SO_TS_BINTIME;
1172 		}
1173 
1174 		switch (ts_clock) {
1175 		case SO_TS_REALTIME_MICRO:
1176 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1177 			    M_TSTMP)) {
1178 				mbuf_tstmp2timespec(m, &ts1);
1179 				timespec2bintime(&ts1, &bt1);
1180 				getboottimebin(&boottimebin);
1181 				bintime_add(&bt1, &boottimebin);
1182 				bintime2timeval(&bt1, &t.tv);
1183 			} else {
1184 				microtime(&t.tv);
1185 			}
1186 			*mp = sbcreatecontrol(&t.tv, sizeof(t.tv),
1187 			    SCM_TIMESTAMP, SOL_SOCKET, M_NOWAIT);
1188 			if (*mp != NULL) {
1189 				mp = &(*mp)->m_next;
1190 				stamped = true;
1191 			}
1192 			break;
1193 
1194 		case SO_TS_BINTIME:
1195 			break;
1196 
1197 		case SO_TS_REALTIME:
1198 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1199 			    M_TSTMP)) {
1200 				mbuf_tstmp2timespec(m, &t.ts);
1201 				getboottimebin(&boottimebin);
1202 				bintime2timespec(&boottimebin, &ts1);
1203 				timespecadd(&t.ts, &ts1, &t.ts);
1204 			} else {
1205 				nanotime(&t.ts);
1206 			}
1207 			*mp = sbcreatecontrol(&t.ts, sizeof(t.ts),
1208 			    SCM_REALTIME, SOL_SOCKET, M_NOWAIT);
1209 			if (*mp != NULL) {
1210 				mp = &(*mp)->m_next;
1211 				stamped = true;
1212 			}
1213 			break;
1214 
1215 		case SO_TS_MONOTONIC:
1216 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1217 			    M_TSTMP))
1218 				mbuf_tstmp2timespec(m, &t.ts);
1219 			else
1220 				nanouptime(&t.ts);
1221 			*mp = sbcreatecontrol(&t.ts, sizeof(t.ts),
1222 			    SCM_MONOTONIC, SOL_SOCKET, M_NOWAIT);
1223 			if (*mp != NULL) {
1224 				mp = &(*mp)->m_next;
1225 				stamped = true;
1226 			}
1227 			break;
1228 
1229 		default:
1230 			panic("unknown (corrupted) so_ts_clock");
1231 		}
1232 		if (stamped && (m->m_flags & (M_PKTHDR | M_TSTMP)) ==
1233 		    (M_PKTHDR | M_TSTMP)) {
1234 			struct sock_timestamp_info sti;
1235 
1236 			bzero(&sti, sizeof(sti));
1237 			sti.st_info_flags = ST_INFO_HW;
1238 			if ((m->m_flags & M_TSTMP_HPREC) != 0)
1239 				sti.st_info_flags |= ST_INFO_HW_HPREC;
1240 			*mp = sbcreatecontrol(&sti, sizeof(sti), SCM_TIME_INFO,
1241 			    SOL_SOCKET, M_NOWAIT);
1242 			if (*mp != NULL)
1243 				mp = &(*mp)->m_next;
1244 		}
1245 	}
1246 #endif
1247 
1248 #define IS2292(inp, x, y)	(((inp)->inp_flags & IN6P_RFC2292) ? (x) : (y))
1249 	/* RFC 2292 sec. 5 */
1250 	if ((inp->inp_flags & IN6P_PKTINFO) != 0) {
1251 		struct in6_pktinfo pi6;
1252 
1253 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1254 #ifdef INET
1255 			struct ip *ip;
1256 
1257 			ip = mtod(m, struct ip *);
1258 			pi6.ipi6_addr.s6_addr32[0] = 0;
1259 			pi6.ipi6_addr.s6_addr32[1] = 0;
1260 			pi6.ipi6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
1261 			pi6.ipi6_addr.s6_addr32[3] = ip->ip_dst.s_addr;
1262 #else
1263 			/* We won't hit this code */
1264 			bzero(&pi6.ipi6_addr, sizeof(struct in6_addr));
1265 #endif
1266 		} else {
1267 			bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
1268 			in6_clearscope(&pi6.ipi6_addr);	/* XXX */
1269 		}
1270 		pi6.ipi6_ifindex =
1271 		    (m && m->m_pkthdr.rcvif) ? m->m_pkthdr.rcvif->if_index : 0;
1272 
1273 		*mp = sbcreatecontrol(&pi6, sizeof(struct in6_pktinfo),
1274 		    IS2292(inp, IPV6_2292PKTINFO, IPV6_PKTINFO), IPPROTO_IPV6,
1275 		    M_NOWAIT);
1276 		if (*mp)
1277 			mp = &(*mp)->m_next;
1278 	}
1279 
1280 	if ((inp->inp_flags & IN6P_HOPLIMIT) != 0) {
1281 		int hlim;
1282 
1283 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1284 #ifdef INET
1285 			struct ip *ip;
1286 
1287 			ip = mtod(m, struct ip *);
1288 			hlim = ip->ip_ttl;
1289 #else
1290 			/* We won't hit this code */
1291 			hlim = 0;
1292 #endif
1293 		} else {
1294 			hlim = ip6->ip6_hlim & 0xff;
1295 		}
1296 		*mp = sbcreatecontrol(&hlim, sizeof(int),
1297 		    IS2292(inp, IPV6_2292HOPLIMIT, IPV6_HOPLIMIT),
1298 		    IPPROTO_IPV6, M_NOWAIT);
1299 		if (*mp)
1300 			mp = &(*mp)->m_next;
1301 	}
1302 
1303 	if ((inp->inp_flags & IN6P_TCLASS) != 0) {
1304 		int tclass;
1305 
1306 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1307 #ifdef INET
1308 			struct ip *ip;
1309 
1310 			ip = mtod(m, struct ip *);
1311 			tclass = ip->ip_tos;
1312 #else
1313 			/* We won't hit this code */
1314 			tclass = 0;
1315 #endif
1316 		} else {
1317 			u_int32_t flowinfo;
1318 
1319 			flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
1320 			flowinfo >>= 20;
1321 			tclass = flowinfo & 0xff;
1322 		}
1323 		*mp = sbcreatecontrol(&tclass, sizeof(int), IPV6_TCLASS,
1324 		    IPPROTO_IPV6, M_NOWAIT);
1325 		if (*mp)
1326 			mp = &(*mp)->m_next;
1327 	}
1328 
1329 	if (v4only != NULL) {
1330 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1331 			*v4only = 1;
1332 		} else {
1333 			*v4only = 0;
1334 		}
1335 	}
1336 
1337 	return (mp);
1338 }
1339 
1340 void
ip6_savecontrol(struct inpcb * inp,struct mbuf * m,struct mbuf ** mp)1341 ip6_savecontrol(struct inpcb *inp, struct mbuf *m, struct mbuf **mp)
1342 {
1343 	struct ip6_hdr *ip6;
1344 	int v4only = 0;
1345 
1346 	mp = ip6_savecontrol_v4(inp, m, mp, &v4only);
1347 	if (v4only)
1348 		return;
1349 
1350 	ip6 = mtod(m, struct ip6_hdr *);
1351 	/*
1352 	 * IPV6_HOPOPTS socket option.  Recall that we required super-user
1353 	 * privilege for the option (see ip6_ctloutput), but it might be too
1354 	 * strict, since there might be some hop-by-hop options which can be
1355 	 * returned to normal user.
1356 	 * See also RFC 2292 section 6 (or RFC 3542 section 8).
1357 	 */
1358 	if ((inp->inp_flags & IN6P_HOPOPTS) != 0) {
1359 		/*
1360 		 * Check if a hop-by-hop options header is contatined in the
1361 		 * received packet, and if so, store the options as ancillary
1362 		 * data. Note that a hop-by-hop options header must be
1363 		 * just after the IPv6 header, which is assured through the
1364 		 * IPv6 input processing.
1365 		 */
1366 		if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
1367 			struct ip6_hbh *hbh;
1368 			u_int hbhlen;
1369 
1370 			hbh = (struct ip6_hbh *)(ip6 + 1);
1371 			hbhlen = (hbh->ip6h_len + 1) << 3;
1372 
1373 			/*
1374 			 * XXX: We copy the whole header even if a
1375 			 * jumbo payload option is included, the option which
1376 			 * is to be removed before returning according to
1377 			 * RFC2292.
1378 			 * Note: this constraint is removed in RFC3542
1379 			 */
1380 			*mp = sbcreatecontrol(hbh, hbhlen,
1381 			    IS2292(inp, IPV6_2292HOPOPTS, IPV6_HOPOPTS),
1382 			    IPPROTO_IPV6, M_NOWAIT);
1383 			if (*mp)
1384 				mp = &(*mp)->m_next;
1385 		}
1386 	}
1387 
1388 	if ((inp->inp_flags & (IN6P_RTHDR | IN6P_DSTOPTS)) != 0) {
1389 		int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);
1390 
1391 		/*
1392 		 * Search for destination options headers or routing
1393 		 * header(s) through the header chain, and stores each
1394 		 * header as ancillary data.
1395 		 * Note that the order of the headers remains in
1396 		 * the chain of ancillary data.
1397 		 */
1398 		while (1) {	/* is explicit loop prevention necessary? */
1399 			struct ip6_ext *ip6e = NULL;
1400 			u_int elen;
1401 
1402 			/*
1403 			 * if it is not an extension header, don't try to
1404 			 * pull it from the chain.
1405 			 */
1406 			switch (nxt) {
1407 			case IPPROTO_DSTOPTS:
1408 			case IPPROTO_ROUTING:
1409 			case IPPROTO_HOPOPTS:
1410 			case IPPROTO_AH: /* is it possible? */
1411 				break;
1412 			default:
1413 				goto loopend;
1414 			}
1415 
1416 			if (off + sizeof(*ip6e) > m->m_len)
1417 				goto loopend;
1418 			ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
1419 			if (nxt == IPPROTO_AH)
1420 				elen = (ip6e->ip6e_len + 2) << 2;
1421 			else
1422 				elen = (ip6e->ip6e_len + 1) << 3;
1423 			if (off + elen > m->m_len)
1424 				goto loopend;
1425 
1426 			switch (nxt) {
1427 			case IPPROTO_DSTOPTS:
1428 				if (!(inp->inp_flags & IN6P_DSTOPTS))
1429 					break;
1430 
1431 				*mp = sbcreatecontrol(ip6e, elen,
1432 				    IS2292(inp, IPV6_2292DSTOPTS, IPV6_DSTOPTS),
1433 				    IPPROTO_IPV6, M_NOWAIT);
1434 				if (*mp)
1435 					mp = &(*mp)->m_next;
1436 				break;
1437 			case IPPROTO_ROUTING:
1438 				if (!(inp->inp_flags & IN6P_RTHDR))
1439 					break;
1440 
1441 				*mp = sbcreatecontrol(ip6e, elen,
1442 				    IS2292(inp, IPV6_2292RTHDR, IPV6_RTHDR),
1443 				    IPPROTO_IPV6, M_NOWAIT);
1444 				if (*mp)
1445 					mp = &(*mp)->m_next;
1446 				break;
1447 			case IPPROTO_HOPOPTS:
1448 			case IPPROTO_AH: /* is it possible? */
1449 				break;
1450 
1451 			default:
1452 				/*
1453 				 * other cases have been filtered in the above.
1454 				 * none will visit this case.  here we supply
1455 				 * the code just in case (nxt overwritten or
1456 				 * other cases).
1457 				 */
1458 				goto loopend;
1459 			}
1460 
1461 			/* proceed with the next header. */
1462 			off += elen;
1463 			nxt = ip6e->ip6e_nxt;
1464 			ip6e = NULL;
1465 		}
1466 	  loopend:
1467 		;
1468 	}
1469 
1470 	if (inp->inp_flags2 & INP_RECVFLOWID) {
1471 		uint32_t flowid, flow_type;
1472 
1473 		flowid = m->m_pkthdr.flowid;
1474 		flow_type = M_HASHTYPE_GET(m);
1475 
1476 		/*
1477 		 * XXX should handle the failure of one or the
1478 		 * other - don't populate both?
1479 		 */
1480 		*mp = sbcreatecontrol(&flowid, sizeof(uint32_t), IPV6_FLOWID,
1481 		    IPPROTO_IPV6, M_NOWAIT);
1482 		if (*mp)
1483 			mp = &(*mp)->m_next;
1484 		*mp = sbcreatecontrol(&flow_type, sizeof(uint32_t),
1485 		    IPV6_FLOWTYPE, IPPROTO_IPV6, M_NOWAIT);
1486 		if (*mp)
1487 			mp = &(*mp)->m_next;
1488 	}
1489 
1490 #ifdef	RSS
1491 	if (inp->inp_flags2 & INP_RECVRSSBUCKETID) {
1492 		uint32_t flowid, flow_type;
1493 		uint32_t rss_bucketid;
1494 
1495 		flowid = m->m_pkthdr.flowid;
1496 		flow_type = M_HASHTYPE_GET(m);
1497 
1498 		if (rss_hash2bucket(flowid, flow_type, &rss_bucketid) == 0) {
1499 			*mp = sbcreatecontrol(&rss_bucketid, sizeof(uint32_t),
1500 			    IPV6_RSSBUCKETID, IPPROTO_IPV6, M_NOWAIT);
1501 			if (*mp)
1502 				mp = &(*mp)->m_next;
1503 		}
1504 	}
1505 #endif
1506 
1507 }
1508 #undef IS2292
1509 
1510 void
ip6_notify_pmtu(struct inpcb * inp,struct sockaddr_in6 * dst,u_int32_t mtu)1511 ip6_notify_pmtu(struct inpcb *inp, struct sockaddr_in6 *dst, u_int32_t mtu)
1512 {
1513 	struct socket *so;
1514 	struct mbuf *m_mtu;
1515 	struct ip6_mtuinfo mtuctl;
1516 
1517 	KASSERT(inp != NULL, ("%s: inp == NULL", __func__));
1518 	/*
1519 	 * Notify the error by sending IPV6_PATHMTU ancillary data if
1520 	 * application wanted to know the MTU value.
1521 	 * NOTE: we notify disconnected sockets, because some udp
1522 	 * applications keep sending sockets disconnected.
1523 	 * NOTE: our implementation doesn't notify connected sockets that has
1524 	 * foreign address that is different than given destination addresses
1525 	 * (this is permitted by RFC 3542).
1526 	 */
1527 	if ((inp->inp_flags & IN6P_MTU) == 0 || (
1528 	    !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr) &&
1529 	    !IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &dst->sin6_addr)))
1530 		return;
1531 
1532 	mtuctl.ip6m_mtu = mtu;
1533 	mtuctl.ip6m_addr = *dst;
1534 	if (sa6_recoverscope(&mtuctl.ip6m_addr))
1535 		return;
1536 
1537 	if ((m_mtu = sbcreatecontrol(&mtuctl, sizeof(mtuctl), IPV6_PATHMTU,
1538 	    IPPROTO_IPV6, M_NOWAIT)) == NULL)
1539 		return;
1540 
1541 	so =  inp->inp_socket;
1542 	if (sbappendaddr(&so->so_rcv, (struct sockaddr *)dst, NULL, m_mtu)
1543 	    == 0) {
1544 		soroverflow(so);
1545 		m_freem(m_mtu);
1546 		/* XXX: should count statistics */
1547 	} else
1548 		sorwakeup(so);
1549 }
1550 
1551 /*
1552  * Get pointer to the previous header followed by the header
1553  * currently processed.
1554  */
1555 int
ip6_get_prevhdr(const struct mbuf * m,int off)1556 ip6_get_prevhdr(const struct mbuf *m, int off)
1557 {
1558 	struct ip6_ext ip6e;
1559 	struct ip6_hdr *ip6;
1560 	int len, nlen, nxt;
1561 
1562 	if (off == sizeof(struct ip6_hdr))
1563 		return (offsetof(struct ip6_hdr, ip6_nxt));
1564 	if (off < sizeof(struct ip6_hdr))
1565 		panic("%s: off < sizeof(struct ip6_hdr)", __func__);
1566 
1567 	ip6 = mtod(m, struct ip6_hdr *);
1568 	nxt = ip6->ip6_nxt;
1569 	len = sizeof(struct ip6_hdr);
1570 	nlen = 0;
1571 	while (len < off) {
1572 		m_copydata(m, len, sizeof(ip6e), (caddr_t)&ip6e);
1573 		switch (nxt) {
1574 		case IPPROTO_FRAGMENT:
1575 			nlen = sizeof(struct ip6_frag);
1576 			break;
1577 		case IPPROTO_AH:
1578 			nlen = (ip6e.ip6e_len + 2) << 2;
1579 			break;
1580 		default:
1581 			nlen = (ip6e.ip6e_len + 1) << 3;
1582 		}
1583 		len += nlen;
1584 		nxt = ip6e.ip6e_nxt;
1585 	}
1586 	return (len - nlen);
1587 }
1588 
1589 /*
1590  * get next header offset.  m will be retained.
1591  */
1592 int
ip6_nexthdr(const struct mbuf * m,int off,int proto,int * nxtp)1593 ip6_nexthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1594 {
1595 	struct ip6_hdr ip6;
1596 	struct ip6_ext ip6e;
1597 	struct ip6_frag fh;
1598 
1599 	/* just in case */
1600 	if (m == NULL)
1601 		panic("ip6_nexthdr: m == NULL");
1602 	if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
1603 		return -1;
1604 
1605 	switch (proto) {
1606 	case IPPROTO_IPV6:
1607 		if (m->m_pkthdr.len < off + sizeof(ip6))
1608 			return -1;
1609 		m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
1610 		if (nxtp)
1611 			*nxtp = ip6.ip6_nxt;
1612 		off += sizeof(ip6);
1613 		return off;
1614 
1615 	case IPPROTO_FRAGMENT:
1616 		/*
1617 		 * terminate parsing if it is not the first fragment,
1618 		 * it does not make sense to parse through it.
1619 		 */
1620 		if (m->m_pkthdr.len < off + sizeof(fh))
1621 			return -1;
1622 		m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
1623 		/* IP6F_OFF_MASK = 0xfff8(BigEndian), 0xf8ff(LittleEndian) */
1624 		if (fh.ip6f_offlg & IP6F_OFF_MASK)
1625 			return -1;
1626 		if (nxtp)
1627 			*nxtp = fh.ip6f_nxt;
1628 		off += sizeof(struct ip6_frag);
1629 		return off;
1630 
1631 	case IPPROTO_AH:
1632 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1633 			return -1;
1634 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1635 		if (nxtp)
1636 			*nxtp = ip6e.ip6e_nxt;
1637 		off += (ip6e.ip6e_len + 2) << 2;
1638 		return off;
1639 
1640 	case IPPROTO_HOPOPTS:
1641 	case IPPROTO_ROUTING:
1642 	case IPPROTO_DSTOPTS:
1643 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1644 			return -1;
1645 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1646 		if (nxtp)
1647 			*nxtp = ip6e.ip6e_nxt;
1648 		off += (ip6e.ip6e_len + 1) << 3;
1649 		return off;
1650 
1651 	case IPPROTO_NONE:
1652 	case IPPROTO_ESP:
1653 	case IPPROTO_IPCOMP:
1654 		/* give up */
1655 		return -1;
1656 
1657 	default:
1658 		return -1;
1659 	}
1660 
1661 	/* NOTREACHED */
1662 }
1663 
1664 /*
1665  * get offset for the last header in the chain.  m will be kept untainted.
1666  */
1667 int
ip6_lasthdr(const struct mbuf * m,int off,int proto,int * nxtp)1668 ip6_lasthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1669 {
1670 	int newoff;
1671 	int nxt;
1672 
1673 	if (!nxtp) {
1674 		nxt = -1;
1675 		nxtp = &nxt;
1676 	}
1677 	while (1) {
1678 		newoff = ip6_nexthdr(m, off, proto, nxtp);
1679 		if (newoff < 0)
1680 			return off;
1681 		else if (newoff < off)
1682 			return -1;	/* invalid */
1683 		else if (newoff == off)
1684 			return newoff;
1685 
1686 		off = newoff;
1687 		proto = *nxtp;
1688 	}
1689 }
1690