ip6_forward.c revision 139826
162587Sitojun/*	$FreeBSD: head/sys/netinet6/ip6_forward.c 139826 2005-01-07 02:30:35Z imp $	*/
278064Sume/*	$KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $	*/
362587Sitojun
4139826Simp/*-
553541Sshin * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
653541Sshin * All rights reserved.
753541Sshin *
853541Sshin * Redistribution and use in source and binary forms, with or without
953541Sshin * modification, are permitted provided that the following conditions
1053541Sshin * are met:
1153541Sshin * 1. Redistributions of source code must retain the above copyright
1253541Sshin *    notice, this list of conditions and the following disclaimer.
1353541Sshin * 2. Redistributions in binary form must reproduce the above copyright
1453541Sshin *    notice, this list of conditions and the following disclaimer in the
1553541Sshin *    documentation and/or other materials provided with the distribution.
1653541Sshin * 3. Neither the name of the project nor the names of its contributors
1753541Sshin *    may be used to endorse or promote products derived from this software
1853541Sshin *    without specific prior written permission.
1953541Sshin *
2053541Sshin * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
2153541Sshin * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
2253541Sshin * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
2353541Sshin * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
2453541Sshin * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
2553541Sshin * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
2653541Sshin * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
2753541Sshin * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
2853541Sshin * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
2953541Sshin * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
3053541Sshin * SUCH DAMAGE.
3153541Sshin */
3253541Sshin
3362587Sitojun#include "opt_ip6fw.h"
3462587Sitojun#include "opt_inet.h"
3562587Sitojun#include "opt_inet6.h"
3655009Sshin#include "opt_ipsec.h"
3753541Sshin
3853541Sshin#include <sys/param.h>
3953541Sshin#include <sys/systm.h>
4078064Sume#include <sys/malloc.h>
4153541Sshin#include <sys/mbuf.h>
4253541Sshin#include <sys/domain.h>
4353541Sshin#include <sys/protosw.h>
4453541Sshin#include <sys/socket.h>
4553541Sshin#include <sys/errno.h>
4653541Sshin#include <sys/time.h>
4778064Sume#include <sys/kernel.h>
4853541Sshin#include <sys/syslog.h>
4953541Sshin
5053541Sshin#include <net/if.h>
5153541Sshin#include <net/route.h>
5284994Sdarrenr#include <net/pfil.h>
5353541Sshin
5453541Sshin#include <netinet/in.h>
5553541Sshin#include <netinet/in_var.h>
5678064Sume#include <netinet/in_systm.h>
5778064Sume#include <netinet/ip.h>
5862587Sitojun#include <netinet/ip_var.h>
5978064Sume#include <netinet6/in6_var.h>
6062587Sitojun#include <netinet/ip6.h>
6153541Sshin#include <netinet6/ip6_var.h>
6262587Sitojun#include <netinet/icmp6.h>
6353541Sshin#include <netinet6/nd6.h>
6453541Sshin
6578064Sume#include <netinet/in_pcb.h>
6678064Sume
6763256Sitojun#ifdef IPSEC
6853541Sshin#include <netinet6/ipsec.h>
6978064Sume#ifdef INET6
7062601Sitojun#include <netinet6/ipsec6.h>
7178064Sume#endif
7253541Sshin#include <netkey/key.h>
7363256Sitojun#endif /* IPSEC */
7453541Sshin
75105199Ssam#ifdef FAST_IPSEC
76105199Ssam#include <netipsec/ipsec.h>
77105199Ssam#include <netipsec/ipsec6.h>
78105199Ssam#include <netipsec/key.h>
79105199Ssam#define	IPSEC
80105199Ssam#endif /* FAST_IPSEC */
81105199Ssam
8253541Sshin#include <netinet6/ip6_fw.h>
8353541Sshin
8453541Sshin#include <net/net_osdep.h>
8553541Sshin
8684994Sdarrenr#include <netinet6/ip6protosw.h>
8784994Sdarrenr
8853541Sshinstruct	route_in6 ip6_forward_rt;
8953541Sshin
9053541Sshin/*
9153541Sshin * Forward a packet.  If some error occurs return the sender
9253541Sshin * an icmp packet.  Note we can't always generate a meaningful
9353541Sshin * icmp message because icmp doesn't have a large enough repertoire
9453541Sshin * of codes and types.
9553541Sshin *
9653541Sshin * If not forwarding, just drop the packet.  This could be confusing
9753541Sshin * if ipforwarding was zero but some routing protocol was advancing
9853541Sshin * us as a gateway to somewhere.  However, we must let the routing
9953541Sshin * protocol deal with that.
10053541Sshin *
10153541Sshin */
10253541Sshin
10353541Sshinvoid
10453541Sshinip6_forward(m, srcrt)
10553541Sshin	struct mbuf *m;
10653541Sshin	int srcrt;
10753541Sshin{
10853541Sshin	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
109122062Sume	struct sockaddr_in6 *dst = NULL;
110122062Sume	struct rtentry *rt = NULL;
11153541Sshin	int error, type = 0, code = 0;
11262587Sitojun	struct mbuf *mcopy = NULL;
11362587Sitojun	struct ifnet *origifp;	/* maybe unnecessary */
114121315Sume	u_int32_t srczone, dstzone;
11563256Sitojun#ifdef IPSEC
11653541Sshin	struct secpolicy *sp = NULL;
117122062Sume	int ipsecrt = 0;
11853541Sshin#endif
11953541Sshin
12063256Sitojun#ifdef IPSEC
12153541Sshin	/*
12253541Sshin	 * Check AH/ESP integrity.
12353541Sshin	 */
12453541Sshin	/*
12553541Sshin	 * Don't increment ip6s_cantforward because this is the check
12653541Sshin	 * before forwarding packet actually.
12753541Sshin	 */
12853541Sshin	if (ipsec6_in_reject(m, NULL)) {
129105199Ssam#if !defined(FAST_IPSEC)
13053541Sshin		ipsec6stat.in_polvio++;
131105199Ssam#endif
13253541Sshin		m_freem(m);
13353541Sshin		return;
13453541Sshin	}
13595023Ssuz#endif /* IPSEC */
13653541Sshin
13778064Sume	/*
13878064Sume	 * Do not forward packets to multicast destination (should be handled
13978064Sume	 * by ip6_mforward().
14078064Sume	 * Do not forward packets with unspecified source.  It was discussed
141120913Sume	 * in July 2000, on the ipngwg mailing list.
14278064Sume	 */
14362587Sitojun	if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
14478064Sume	    IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
14578064Sume	    IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
14653541Sshin		ip6stat.ip6s_cantforward++;
14753541Sshin		/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
14853541Sshin		if (ip6_log_time + ip6_log_interval < time_second) {
14953541Sshin			ip6_log_time = time_second;
15053541Sshin			log(LOG_DEBUG,
15153541Sshin			    "cannot forward "
15253541Sshin			    "from %s to %s nxt %d received on %s\n",
15362587Sitojun			    ip6_sprintf(&ip6->ip6_src),
15462587Sitojun			    ip6_sprintf(&ip6->ip6_dst),
15553541Sshin			    ip6->ip6_nxt,
15653541Sshin			    if_name(m->m_pkthdr.rcvif));
15753541Sshin		}
15853541Sshin		m_freem(m);
15953541Sshin		return;
16053541Sshin	}
16153541Sshin
16253541Sshin	if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
16353541Sshin		/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
16453541Sshin		icmp6_error(m, ICMP6_TIME_EXCEEDED,
16553541Sshin				ICMP6_TIME_EXCEED_TRANSIT, 0);
16653541Sshin		return;
16753541Sshin	}
16853541Sshin	ip6->ip6_hlim -= IPV6_HLIMDEC;
16953541Sshin
17062587Sitojun	/*
17162587Sitojun	 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
17262587Sitojun	 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
17362587Sitojun	 * we need to generate an ICMP6 message to the src.
17462587Sitojun	 * Thanks to M_EXT, in most cases copy will not occur.
17562587Sitojun	 *
17662587Sitojun	 * It is important to save it before IPsec processing as IPsec
17762587Sitojun	 * processing may modify the mbuf.
17862587Sitojun	 */
17962587Sitojun	mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
18062587Sitojun
18163256Sitojun#ifdef IPSEC
18253541Sshin	/* get a security policy for this packet */
183120913Sume	sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
184120913Sume	    IP_FORWARDING, &error);
18553541Sshin	if (sp == NULL) {
18653541Sshin		ipsec6stat.out_inval++;
18753541Sshin		ip6stat.ip6s_cantforward++;
18862587Sitojun		if (mcopy) {
18962587Sitojun#if 0
19062587Sitojun			/* XXX: what icmp ? */
19162587Sitojun#else
19262587Sitojun			m_freem(mcopy);
19362587Sitojun#endif
19462587Sitojun		}
19553541Sshin		m_freem(m);
19653541Sshin		return;
19753541Sshin	}
19853541Sshin
19953541Sshin	error = 0;
20053541Sshin
20153541Sshin	/* check policy */
20253541Sshin	switch (sp->policy) {
20353541Sshin	case IPSEC_POLICY_DISCARD:
20453541Sshin		/*
20553541Sshin		 * This packet is just discarded.
20653541Sshin		 */
20753541Sshin		ipsec6stat.out_polvio++;
20853541Sshin		ip6stat.ip6s_cantforward++;
20953541Sshin		key_freesp(sp);
21062587Sitojun		if (mcopy) {
21162587Sitojun#if 0
21262587Sitojun			/* XXX: what icmp ? */
21362587Sitojun#else
21462587Sitojun			m_freem(mcopy);
21562587Sitojun#endif
21662587Sitojun		}
21753541Sshin		m_freem(m);
21853541Sshin		return;
21953541Sshin
22053541Sshin	case IPSEC_POLICY_BYPASS:
22153541Sshin	case IPSEC_POLICY_NONE:
22253541Sshin		/* no need to do IPsec. */
22353541Sshin		key_freesp(sp);
22453541Sshin		goto skip_ipsec;
22562587Sitojun
22653541Sshin	case IPSEC_POLICY_IPSEC:
22753541Sshin		if (sp->req == NULL) {
22853541Sshin			/* XXX should be panic ? */
22953541Sshin			printf("ip6_forward: No IPsec request specified.\n");
23053541Sshin			ip6stat.ip6s_cantforward++;
23153541Sshin			key_freesp(sp);
23262587Sitojun			if (mcopy) {
23362587Sitojun#if 0
23462587Sitojun				/* XXX: what icmp ? */
23562587Sitojun#else
23662587Sitojun				m_freem(mcopy);
23762587Sitojun#endif
23862587Sitojun			}
23953541Sshin			m_freem(m);
24053541Sshin			return;
24153541Sshin		}
24253541Sshin		/* do IPsec */
24353541Sshin		break;
24453541Sshin
24553541Sshin	case IPSEC_POLICY_ENTRUST:
24653541Sshin	default:
24753541Sshin		/* should be panic ?? */
24853541Sshin		printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
24953541Sshin		key_freesp(sp);
25053541Sshin		goto skip_ipsec;
25153541Sshin	}
25253541Sshin
25353541Sshin    {
254122062Sume	struct ipsecrequest *isr = NULL;
25553541Sshin	struct ipsec_output_state state;
25653541Sshin
25753541Sshin	/*
258122062Sume	 * when the kernel forwards a packet, it is not proper to apply
259122062Sume	 * IPsec transport mode to the packet is not proper.  this check
260122062Sume	 * avoid from this.
261122062Sume	 * at present, if there is even a transport mode SA request in the
262122062Sume	 * security policy, the kernel does not apply IPsec to the packet.
263122062Sume	 * this check is not enough because the following case is valid.
264122062Sume	 *      ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
265122062Sume	 */
266122062Sume	for (isr = sp->req; isr; isr = isr->next) {
267126006Sume		if (isr->saidx.mode == IPSEC_MODE_ANY)
268126006Sume			goto doipsectunnel;
269126006Sume		if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
270126006Sume			goto doipsectunnel;
271122062Sume	}
272122062Sume
273122062Sume	/*
274126006Sume	 * if there's no need for tunnel mode IPsec, skip.
275126006Sume	 */
276126006Sume	if (!isr)
277126006Sume		goto skip_ipsec;
278126006Sume
279126006Sume    doipsectunnel:
280126006Sume	/*
28153541Sshin	 * All the extension headers will become inaccessible
28253541Sshin	 * (since they can be encrypted).
28353541Sshin	 * Don't panic, we need no more updates to extension headers
28453541Sshin	 * on inner IPv6 packet (since they are now encapsulated).
28553541Sshin	 *
28653541Sshin	 * IPv6 [ESP|AH] IPv6 [extension headers] payload
28753541Sshin	 */
28853541Sshin	bzero(&state, sizeof(state));
28953541Sshin	state.m = m;
29053541Sshin	state.ro = NULL;	/* update at ipsec6_output_tunnel() */
29153541Sshin	state.dst = NULL;	/* update at ipsec6_output_tunnel() */
29253541Sshin
29353541Sshin	error = ipsec6_output_tunnel(&state, sp, 0);
29453541Sshin
29553541Sshin	m = state.m;
29653541Sshin	key_freesp(sp);
29753541Sshin
29853541Sshin	if (error) {
29953541Sshin		/* mbuf is already reclaimed in ipsec6_output_tunnel. */
30053541Sshin		switch (error) {
30153541Sshin		case EHOSTUNREACH:
30253541Sshin		case ENETUNREACH:
30353541Sshin		case EMSGSIZE:
30453541Sshin		case ENOBUFS:
30553541Sshin		case ENOMEM:
30653541Sshin			break;
30753541Sshin		default:
30853541Sshin			printf("ip6_output (ipsec): error code %d\n", error);
309120913Sume			/* FALLTHROUGH */
31053541Sshin		case ENOENT:
31153541Sshin			/* don't show these error codes to the user */
31253541Sshin			break;
31353541Sshin		}
31453541Sshin		ip6stat.ip6s_cantforward++;
31562587Sitojun		if (mcopy) {
31662587Sitojun#if 0
31762587Sitojun			/* XXX: what icmp ? */
31862587Sitojun#else
31962587Sitojun			m_freem(mcopy);
32062587Sitojun#endif
32162587Sitojun		}
32253541Sshin		m_freem(m);
32353541Sshin		return;
32453541Sshin	}
325122062Sume
326126006Sume	if (ip6 != mtod(m, struct ip6_hdr *)) {
327126006Sume		/*
328126006Sume		 * now tunnel mode headers are added.  we are originating
329126006Sume		 * packet instead of forwarding the packet.
330126006Sume		 */
331126006Sume		ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
332126006Sume		    NULL);
333126006Sume		goto freecopy;
334126006Sume	}
335126006Sume
336122062Sume	/* adjust pointer */
337122062Sume	dst = (struct sockaddr_in6 *)state.dst;
338122062Sume	rt = state.ro ? state.ro->ro_rt : NULL;
339122062Sume	if (dst != NULL && rt != NULL)
340122062Sume		ipsecrt = 1;
34153541Sshin    }
34253541Sshin    skip_ipsec:
34363256Sitojun#endif /* IPSEC */
34453541Sshin
345122062Sume#ifdef IPSEC
346122062Sume	if (ipsecrt)
347122062Sume		goto skip_routing;
348122062Sume#endif
349122062Sume
35078064Sume	dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
35153541Sshin	if (!srcrt) {
352120913Sume		/* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */
35353541Sshin		if (ip6_forward_rt.ro_rt == 0 ||
35453541Sshin		    (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
35553541Sshin			if (ip6_forward_rt.ro_rt) {
35653541Sshin				RTFREE(ip6_forward_rt.ro_rt);
35753541Sshin				ip6_forward_rt.ro_rt = 0;
35853541Sshin			}
359120913Sume
36053541Sshin			/* this probably fails but give it a try again */
361122921Sandre			rtalloc((struct route *)&ip6_forward_rt);
36253541Sshin		}
36362587Sitojun
36453541Sshin		if (ip6_forward_rt.ro_rt == 0) {
36553541Sshin			ip6stat.ip6s_noroute++;
36678064Sume			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
36762587Sitojun			if (mcopy) {
36862587Sitojun				icmp6_error(mcopy, ICMP6_DST_UNREACH,
36962587Sitojun					    ICMP6_DST_UNREACH_NOROUTE, 0);
37062587Sitojun			}
37162587Sitojun			m_freem(m);
37253541Sshin			return;
37353541Sshin		}
37453541Sshin	} else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
375120913Sume		   !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
37653541Sshin		if (ip6_forward_rt.ro_rt) {
37753541Sshin			RTFREE(ip6_forward_rt.ro_rt);
37853541Sshin			ip6_forward_rt.ro_rt = 0;
37953541Sshin		}
38053541Sshin		bzero(dst, sizeof(*dst));
38153541Sshin		dst->sin6_len = sizeof(struct sockaddr_in6);
38253541Sshin		dst->sin6_family = AF_INET6;
38353541Sshin		dst->sin6_addr = ip6->ip6_dst;
38453541Sshin
385122921Sandre  		rtalloc((struct route *)&ip6_forward_rt);
38653541Sshin		if (ip6_forward_rt.ro_rt == 0) {
38753541Sshin			ip6stat.ip6s_noroute++;
38878064Sume			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
38962587Sitojun			if (mcopy) {
39062587Sitojun				icmp6_error(mcopy, ICMP6_DST_UNREACH,
39162587Sitojun					    ICMP6_DST_UNREACH_NOROUTE, 0);
39262587Sitojun			}
39362587Sitojun			m_freem(m);
39453541Sshin			return;
39553541Sshin		}
39653541Sshin	}
39753541Sshin	rt = ip6_forward_rt.ro_rt;
398122062Sume#ifdef IPSEC
399122062Sume    skip_routing:;
400122062Sume#endif
40162587Sitojun
40262587Sitojun	/*
40362587Sitojun	 * Scope check: if a packet can't be delivered to its destination
40462587Sitojun	 * for the reason that the destination is beyond the scope of the
40562587Sitojun	 * source address, discard the packet and return an icmp6 destination
40662587Sitojun	 * unreachable error with Code 2 (beyond scope of source address).
40795023Ssuz	 * [draft-ietf-ipngwg-icmp-v3-02.txt, Section 3.1]
40862587Sitojun	 */
409121315Sume	if (in6_addr2zoneid(m->m_pkthdr.rcvif, &ip6->ip6_src, &srczone) ||
410122062Sume	    in6_addr2zoneid(rt->rt_ifp, &ip6->ip6_src, &dstzone)) {
411122062Sume		/* XXX: this should not happen */
41262587Sitojun		ip6stat.ip6s_cantforward++;
41362587Sitojun		ip6stat.ip6s_badscope++;
414122062Sume		m_freem(m);
415122062Sume		return;
416122062Sume	}
417122062Sume	if (srczone != dstzone
418122062Sume#ifdef IPSEC
419122062Sume	    && !ipsecrt
420122062Sume#endif
421122062Sume	    ) {
422122062Sume		ip6stat.ip6s_cantforward++;
423122062Sume		ip6stat.ip6s_badscope++;
42462587Sitojun		in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
42562587Sitojun
42662587Sitojun		if (ip6_log_time + ip6_log_interval < time_second) {
42762587Sitojun			ip6_log_time = time_second;
42862587Sitojun			log(LOG_DEBUG,
42962587Sitojun			    "cannot forward "
43062587Sitojun			    "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
43162587Sitojun			    ip6_sprintf(&ip6->ip6_src),
43262587Sitojun			    ip6_sprintf(&ip6->ip6_dst),
43362587Sitojun			    ip6->ip6_nxt,
43462587Sitojun			    if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
43562587Sitojun		}
43662587Sitojun		if (mcopy)
43762587Sitojun			icmp6_error(mcopy, ICMP6_DST_UNREACH,
43862587Sitojun				    ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
43962587Sitojun		m_freem(m);
44062587Sitojun		return;
44162587Sitojun	}
44262587Sitojun
443121283Sume	if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
44453541Sshin		in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
44562587Sitojun		if (mcopy) {
44662587Sitojun			u_long mtu;
44763256Sitojun#ifdef IPSEC
44862587Sitojun			struct secpolicy *sp;
44962587Sitojun			int ipsecerror;
45062587Sitojun			size_t ipsechdrsiz;
45162587Sitojun#endif
45262587Sitojun
453121283Sume			mtu = IN6_LINKMTU(rt->rt_ifp);
45463256Sitojun#ifdef IPSEC
45562587Sitojun			/*
45662587Sitojun			 * When we do IPsec tunnel ingress, we need to play
457122062Sume			 * with the link value (decrement IPsec header size
45862587Sitojun			 * from mtu value).  The code is much simpler than v4
45962587Sitojun			 * case, as we have the outgoing interface for
46062587Sitojun			 * encapsulated packet as "rt->rt_ifp".
46162587Sitojun			 */
46262587Sitojun			sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
46362587Sitojun				IP_FORWARDING, &ipsecerror);
46462587Sitojun			if (sp) {
46562587Sitojun				ipsechdrsiz = ipsec6_hdrsiz(mcopy,
46662587Sitojun					IPSEC_DIR_OUTBOUND, NULL);
46762587Sitojun				if (ipsechdrsiz < mtu)
46862587Sitojun					mtu -= ipsechdrsiz;
46962587Sitojun			}
47062587Sitojun
47162587Sitojun			/*
47262587Sitojun			 * if mtu becomes less than minimum MTU,
47362587Sitojun			 * tell minimum MTU (and I'll need to fragment it).
47462587Sitojun			 */
47562587Sitojun			if (mtu < IPV6_MMTU)
47662587Sitojun				mtu = IPV6_MMTU;
47762587Sitojun#endif
47862587Sitojun			icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
47962587Sitojun		}
48062587Sitojun		m_freem(m);
48153541Sshin		return;
482120913Sume	}
48353541Sshin
48453541Sshin	if (rt->rt_flags & RTF_GATEWAY)
48553541Sshin		dst = (struct sockaddr_in6 *)rt->rt_gateway;
48653541Sshin
48753541Sshin	/*
48853541Sshin	 * If we are to forward the packet using the same interface
48953541Sshin	 * as one we got the packet from, perhaps we should send a redirect
49053541Sshin	 * to sender to shortcut a hop.
49153541Sshin	 * Only send redirect if source is sending directly to us,
49253541Sshin	 * and if packet was not source routed (or has any options).
49353541Sshin	 * Also, don't send redirect if forwarding using a route
49453541Sshin	 * modified by a redirect.
49553541Sshin	 */
49653541Sshin	if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
497122062Sume#ifdef IPSEC
498122062Sume	    !ipsecrt &&
499122062Sume#endif
50078064Sume	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
50178064Sume		if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
50278064Sume			/*
50378064Sume			 * If the incoming interface is equal to the outgoing
50478064Sume			 * one, and the link attached to the interface is
50578064Sume			 * point-to-point, then it will be highly probable
50678064Sume			 * that a routing loop occurs. Thus, we immediately
50778064Sume			 * drop the packet and send an ICMPv6 error message.
50878064Sume			 *
50978064Sume			 * type/code is based on suggestion by Rich Draves.
51078064Sume			 * not sure if it is the best pick.
51178064Sume			 */
51278064Sume			icmp6_error(mcopy, ICMP6_DST_UNREACH,
51378064Sume				    ICMP6_DST_UNREACH_ADDR, 0);
51478064Sume			m_freem(m);
51578064Sume			return;
51678064Sume		}
51753541Sshin		type = ND_REDIRECT;
51878064Sume	}
51953541Sshin
52053541Sshin	/*
52153541Sshin	 * Check with the firewall...
52253541Sshin	 */
52366303Sume	if (ip6_fw_enable && ip6_fw_chk_ptr) {
52453541Sshin		u_short port = 0;
52553541Sshin		/* If ipfw says divert, we have to just drop packet */
52653541Sshin		if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
52753541Sshin			m_freem(m);
52853541Sshin			goto freecopy;
52953541Sshin		}
53053541Sshin		if (!m)
53153541Sshin			goto freecopy;
53253541Sshin	}
53353541Sshin
53462587Sitojun	/*
53562587Sitojun	 * Fake scoped addresses. Note that even link-local source or
53662587Sitojun	 * destinaion can appear, if the originating node just sends the
53762587Sitojun	 * packet to us (without address resolution for the destination).
53862587Sitojun	 * Since both icmp6_error and icmp6_redirect_output fill the embedded
53978064Sume	 * link identifiers, we can do this stuff after making a copy for
54078064Sume	 * returning an error.
54162587Sitojun	 */
54262587Sitojun	if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
54362587Sitojun		/*
54462587Sitojun		 * See corresponding comments in ip6_output.
54562587Sitojun		 * XXX: but is it possible that ip6_forward() sends a packet
54662587Sitojun		 *      to a loopback interface? I don't think so, and thus
54762587Sitojun		 *      I bark here. (jinmei@kame.net)
54862587Sitojun		 * XXX: it is common to route invalid packets to loopback.
54962587Sitojun		 *	also, the codepath will be visited on use of ::1 in
55062587Sitojun		 *	rthdr. (itojun)
55162587Sitojun		 */
55262587Sitojun#if 1
55362587Sitojun		if (0)
55462587Sitojun#else
55562587Sitojun		if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
55662587Sitojun#endif
55762587Sitojun		{
55862587Sitojun			printf("ip6_forward: outgoing interface is loopback. "
559120913Sume			       "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
560120913Sume			       ip6_sprintf(&ip6->ip6_src),
561120913Sume			       ip6_sprintf(&ip6->ip6_dst),
562120913Sume			       ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
563120913Sume			       if_name(rt->rt_ifp));
56462587Sitojun		}
56562587Sitojun
56678064Sume		/* we can just use rcvif in forwarding. */
56778064Sume		origifp = m->m_pkthdr.rcvif;
56862587Sitojun	}
56962587Sitojun	else
57062587Sitojun		origifp = rt->rt_ifp;
57178064Sume	/*
57278064Sume	 * clear embedded scope identifiers if necessary.
57378064Sume	 * in6_clearscope will touch the addresses only when necessary.
57478064Sume	 */
57578064Sume	in6_clearscope(&ip6->ip6_src);
57678064Sume	in6_clearscope(&ip6->ip6_dst);
57762587Sitojun
578134383Sandre	/* Jump over all PFIL processing if hooks are not active. */
579134383Sandre	if (inet6_pfil_hook.ph_busy_count == -1)
580134383Sandre		goto pass;
581134383Sandre
582134383Sandre	/* Run through list of hooks for output packets. */
583135920Smlaier	error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
584120593Ssam	if (error != 0)
585120593Ssam		goto senderr;
586120386Ssam	if (m == NULL)
587120386Ssam		goto freecopy;
588120386Ssam	ip6 = mtod(m, struct ip6_hdr *);
58984994Sdarrenr
590134383Sandrepass:
59162587Sitojun	error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
59253541Sshin	if (error) {
59353541Sshin		in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
59453541Sshin		ip6stat.ip6s_cantforward++;
59553541Sshin	} else {
59653541Sshin		ip6stat.ip6s_forward++;
59753541Sshin		in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
59853541Sshin		if (type)
59953541Sshin			ip6stat.ip6s_redirectsent++;
60053541Sshin		else {
60153541Sshin			if (mcopy)
60253541Sshin				goto freecopy;
60353541Sshin		}
60453541Sshin	}
605120913Sume
606120593Ssamsenderr:
60753541Sshin	if (mcopy == NULL)
60853541Sshin		return;
60953541Sshin	switch (error) {
61053541Sshin	case 0:
61153541Sshin		if (type == ND_REDIRECT) {
61253541Sshin			icmp6_redirect_output(mcopy, rt);
61353541Sshin			return;
61453541Sshin		}
61553541Sshin		goto freecopy;
61653541Sshin
61753541Sshin	case EMSGSIZE:
61853541Sshin		/* xxx MTU is constant in PPP? */
61953541Sshin		goto freecopy;
62053541Sshin
62153541Sshin	case ENOBUFS:
62253541Sshin		/* Tell source to slow down like source quench in IP? */
62353541Sshin		goto freecopy;
62453541Sshin
62553541Sshin	case ENETUNREACH:	/* shouldn't happen, checked above */
62653541Sshin	case EHOSTUNREACH:
62753541Sshin	case ENETDOWN:
62853541Sshin	case EHOSTDOWN:
62953541Sshin	default:
63053541Sshin		type = ICMP6_DST_UNREACH;
63153541Sshin		code = ICMP6_DST_UNREACH_ADDR;
63253541Sshin		break;
63353541Sshin	}
63453541Sshin	icmp6_error(mcopy, type, code, 0);
63553541Sshin	return;
63653541Sshin
63753541Sshin freecopy:
63853541Sshin	m_freem(mcopy);
63953541Sshin	return;
64053541Sshin}
641