676 lines
17 KiB
C
676 lines
17 KiB
C
/* $FreeBSD$ */
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/* $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $ */
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/*-
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* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the project nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "opt_ip6fw.h"
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#include "opt_ipsec.h"
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#include "opt_ipstealth.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/domain.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/errno.h>
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#include <sys/time.h>
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#include <sys/kernel.h>
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#include <sys/syslog.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <net/pfil.h>
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#include <netinet/in.h>
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#include <netinet/in_var.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/ip_var.h>
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#include <netinet6/in6_var.h>
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#include <netinet/ip6.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/scope6_var.h>
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#include <netinet/icmp6.h>
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#include <netinet6/nd6.h>
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#include <netinet/in_pcb.h>
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#ifdef IPSEC
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#include <netinet6/ipsec.h>
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#ifdef INET6
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#include <netinet6/ipsec6.h>
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#endif
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#include <netkey/key.h>
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#endif /* IPSEC */
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#ifdef FAST_IPSEC
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#include <netipsec/ipsec.h>
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#include <netipsec/ipsec6.h>
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#include <netipsec/key.h>
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#define IPSEC
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#endif /* FAST_IPSEC */
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#include <netinet6/ip6_fw.h>
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#include <net/net_osdep.h>
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#include <netinet6/ip6protosw.h>
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struct route_in6 ip6_forward_rt;
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/*
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* Forward a packet. If some error occurs return the sender
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* an icmp packet. Note we can't always generate a meaningful
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* icmp message because icmp doesn't have a large enough repertoire
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* of codes and types.
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*
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* If not forwarding, just drop the packet. This could be confusing
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* if ipforwarding was zero but some routing protocol was advancing
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* us as a gateway to somewhere. However, we must let the routing
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* protocol deal with that.
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*
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*/
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void
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ip6_forward(m, srcrt)
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struct mbuf *m;
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int srcrt;
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{
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struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
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struct sockaddr_in6 *dst = NULL;
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struct rtentry *rt = NULL;
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int error, type = 0, code = 0;
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struct mbuf *mcopy = NULL;
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struct ifnet *origifp; /* maybe unnecessary */
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u_int32_t inzone, outzone;
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struct in6_addr src_in6, dst_in6;
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#ifdef IPSEC
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struct secpolicy *sp = NULL;
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int ipsecrt = 0;
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#endif
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#ifdef IPSEC
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/*
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* Check AH/ESP integrity.
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*/
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/*
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* Don't increment ip6s_cantforward because this is the check
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* before forwarding packet actually.
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*/
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if (ipsec6_in_reject(m, NULL)) {
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#if !defined(FAST_IPSEC)
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ipsec6stat.in_polvio++;
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#endif
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m_freem(m);
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return;
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}
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#endif /* IPSEC */
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/*
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* Do not forward packets to multicast destination (should be handled
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* by ip6_mforward().
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* Do not forward packets with unspecified source. It was discussed
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* in July 2000, on the ipngwg mailing list.
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*/
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if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
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IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
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IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
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ip6stat.ip6s_cantforward++;
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/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
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if (ip6_log_time + ip6_log_interval < time_second) {
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ip6_log_time = time_second;
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log(LOG_DEBUG,
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"cannot forward "
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"from %s to %s nxt %d received on %s\n",
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ip6_sprintf(&ip6->ip6_src),
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ip6_sprintf(&ip6->ip6_dst),
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ip6->ip6_nxt,
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if_name(m->m_pkthdr.rcvif));
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}
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m_freem(m);
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return;
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}
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#ifdef IPSTEALTH
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if (!ip6stealth) {
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#endif
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if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
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/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
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icmp6_error(m, ICMP6_TIME_EXCEEDED,
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ICMP6_TIME_EXCEED_TRANSIT, 0);
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return;
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}
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ip6->ip6_hlim -= IPV6_HLIMDEC;
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#ifdef IPSTEALTH
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}
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#endif
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/*
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* Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
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* size of IPv6 + ICMPv6 headers) bytes of the packet in case
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* we need to generate an ICMP6 message to the src.
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* Thanks to M_EXT, in most cases copy will not occur.
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*
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* It is important to save it before IPsec processing as IPsec
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* processing may modify the mbuf.
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*/
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mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
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#ifdef IPSEC
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/* get a security policy for this packet */
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sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
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IP_FORWARDING, &error);
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if (sp == NULL) {
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ipsec6stat.out_inval++;
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ip6stat.ip6s_cantforward++;
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if (mcopy) {
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#if 0
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/* XXX: what icmp ? */
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#else
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m_freem(mcopy);
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#endif
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}
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m_freem(m);
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return;
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}
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error = 0;
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/* check policy */
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switch (sp->policy) {
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case IPSEC_POLICY_DISCARD:
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/*
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* This packet is just discarded.
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*/
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ipsec6stat.out_polvio++;
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ip6stat.ip6s_cantforward++;
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key_freesp(sp);
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if (mcopy) {
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#if 0
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/* XXX: what icmp ? */
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#else
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m_freem(mcopy);
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#endif
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}
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m_freem(m);
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return;
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case IPSEC_POLICY_BYPASS:
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case IPSEC_POLICY_NONE:
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/* no need to do IPsec. */
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key_freesp(sp);
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goto skip_ipsec;
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case IPSEC_POLICY_IPSEC:
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if (sp->req == NULL) {
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/* XXX should be panic ? */
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printf("ip6_forward: No IPsec request specified.\n");
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ip6stat.ip6s_cantforward++;
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key_freesp(sp);
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if (mcopy) {
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#if 0
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/* XXX: what icmp ? */
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#else
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m_freem(mcopy);
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#endif
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}
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m_freem(m);
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return;
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}
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/* do IPsec */
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break;
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case IPSEC_POLICY_ENTRUST:
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default:
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/* should be panic ?? */
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printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
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key_freesp(sp);
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goto skip_ipsec;
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}
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{
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struct ipsecrequest *isr = NULL;
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struct ipsec_output_state state;
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/*
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* when the kernel forwards a packet, it is not proper to apply
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* IPsec transport mode to the packet is not proper. this check
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* avoid from this.
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* at present, if there is even a transport mode SA request in the
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* security policy, the kernel does not apply IPsec to the packet.
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* this check is not enough because the following case is valid.
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* ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
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*/
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for (isr = sp->req; isr; isr = isr->next) {
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if (isr->saidx.mode == IPSEC_MODE_ANY)
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goto doipsectunnel;
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if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
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goto doipsectunnel;
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}
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/*
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* if there's no need for tunnel mode IPsec, skip.
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*/
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if (!isr)
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goto skip_ipsec;
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doipsectunnel:
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/*
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* All the extension headers will become inaccessible
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* (since they can be encrypted).
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* Don't panic, we need no more updates to extension headers
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* on inner IPv6 packet (since they are now encapsulated).
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*
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* IPv6 [ESP|AH] IPv6 [extension headers] payload
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*/
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bzero(&state, sizeof(state));
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state.m = m;
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state.ro = NULL; /* update at ipsec6_output_tunnel() */
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state.dst = NULL; /* update at ipsec6_output_tunnel() */
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error = ipsec6_output_tunnel(&state, sp, 0);
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m = state.m;
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key_freesp(sp);
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if (error) {
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/* mbuf is already reclaimed in ipsec6_output_tunnel. */
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switch (error) {
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case EHOSTUNREACH:
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case ENETUNREACH:
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case EMSGSIZE:
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case ENOBUFS:
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case ENOMEM:
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break;
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default:
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printf("ip6_output (ipsec): error code %d\n", error);
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/* FALLTHROUGH */
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case ENOENT:
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/* don't show these error codes to the user */
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break;
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}
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ip6stat.ip6s_cantforward++;
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if (mcopy) {
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#if 0
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/* XXX: what icmp ? */
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#else
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m_freem(mcopy);
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#endif
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}
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m_freem(m);
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return;
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}
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if (ip6 != mtod(m, struct ip6_hdr *)) {
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/*
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* now tunnel mode headers are added. we are originating
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* packet instead of forwarding the packet.
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*/
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ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
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NULL);
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goto freecopy;
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}
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/* adjust pointer */
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dst = (struct sockaddr_in6 *)state.dst;
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rt = state.ro ? state.ro->ro_rt : NULL;
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if (dst != NULL && rt != NULL)
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ipsecrt = 1;
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}
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skip_ipsec:
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#endif /* IPSEC */
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#ifdef IPSEC
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if (ipsecrt)
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goto skip_routing;
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#endif
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dst = (struct sockaddr_in6 *)&ip6_forward_rt.ro_dst;
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if (!srcrt) {
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/* ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst */
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if (ip6_forward_rt.ro_rt == 0 ||
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(ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) {
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if (ip6_forward_rt.ro_rt) {
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RTFREE(ip6_forward_rt.ro_rt);
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ip6_forward_rt.ro_rt = 0;
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}
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/* this probably fails but give it a try again */
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rtalloc((struct route *)&ip6_forward_rt);
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}
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if (ip6_forward_rt.ro_rt == 0) {
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ip6stat.ip6s_noroute++;
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in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
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if (mcopy) {
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icmp6_error(mcopy, ICMP6_DST_UNREACH,
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ICMP6_DST_UNREACH_NOROUTE, 0);
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}
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m_freem(m);
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return;
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}
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} else if ((rt = ip6_forward_rt.ro_rt) == 0 ||
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!IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) {
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if (ip6_forward_rt.ro_rt) {
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RTFREE(ip6_forward_rt.ro_rt);
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ip6_forward_rt.ro_rt = 0;
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}
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bzero(dst, sizeof(*dst));
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dst->sin6_len = sizeof(struct sockaddr_in6);
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dst->sin6_family = AF_INET6;
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dst->sin6_addr = ip6->ip6_dst;
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rtalloc((struct route *)&ip6_forward_rt);
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if (ip6_forward_rt.ro_rt == 0) {
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ip6stat.ip6s_noroute++;
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in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
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if (mcopy) {
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icmp6_error(mcopy, ICMP6_DST_UNREACH,
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ICMP6_DST_UNREACH_NOROUTE, 0);
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}
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m_freem(m);
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return;
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}
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}
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rt = ip6_forward_rt.ro_rt;
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#ifdef IPSEC
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skip_routing:;
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#endif
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/*
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* Source scope check: if a packet can't be delivered to its
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* destination for the reason that the destination is beyond the scope
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* of the source address, discard the packet and return an icmp6
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* destination unreachable error with Code 2 (beyond scope of source
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* address). We use a local copy of ip6_src, since in6_setscope()
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* will possibly modify its first argument.
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* [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
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*/
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src_in6 = ip6->ip6_src;
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if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
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/* XXX: this should not happen */
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ip6stat.ip6s_cantforward++;
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ip6stat.ip6s_badscope++;
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m_freem(m);
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return;
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}
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if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
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ip6stat.ip6s_cantforward++;
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ip6stat.ip6s_badscope++;
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m_freem(m);
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return;
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}
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if (inzone != outzone
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#ifdef IPSEC
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&& !ipsecrt
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#endif
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) {
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ip6stat.ip6s_cantforward++;
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ip6stat.ip6s_badscope++;
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in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
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if (ip6_log_time + ip6_log_interval < time_second) {
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ip6_log_time = time_second;
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log(LOG_DEBUG,
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"cannot forward "
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"src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
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ip6_sprintf(&ip6->ip6_src),
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ip6_sprintf(&ip6->ip6_dst),
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ip6->ip6_nxt,
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if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp));
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}
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if (mcopy)
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icmp6_error(mcopy, ICMP6_DST_UNREACH,
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ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
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m_freem(m);
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return;
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}
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/*
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* Destination scope check: if a packet is going to break the scope
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* zone of packet's destination address, discard it. This case should
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* usually be prevented by appropriately-configured routing table, but
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* we need an explicit check because we may mistakenly forward the
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* packet to a different zone by (e.g.) a default route.
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*/
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dst_in6 = ip6->ip6_dst;
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if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
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in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
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inzone != outzone) {
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ip6stat.ip6s_cantforward++;
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ip6stat.ip6s_badscope++;
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m_freem(m);
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return;
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}
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if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
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in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
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if (mcopy) {
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u_long mtu;
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#ifdef IPSEC
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struct secpolicy *sp;
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int ipsecerror;
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size_t ipsechdrsiz;
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#endif
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mtu = IN6_LINKMTU(rt->rt_ifp);
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#ifdef IPSEC
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/*
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* When we do IPsec tunnel ingress, we need to play
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* with the link value (decrement IPsec header size
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* from mtu value). The code is much simpler than v4
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* case, as we have the outgoing interface for
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* encapsulated packet as "rt->rt_ifp".
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*/
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sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
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|
IP_FORWARDING, &ipsecerror);
|
|
if (sp) {
|
|
ipsechdrsiz = ipsec6_hdrsiz(mcopy,
|
|
IPSEC_DIR_OUTBOUND, NULL);
|
|
if (ipsechdrsiz < mtu)
|
|
mtu -= ipsechdrsiz;
|
|
}
|
|
|
|
/*
|
|
* if mtu becomes less than minimum MTU,
|
|
* tell minimum MTU (and I'll need to fragment it).
|
|
*/
|
|
if (mtu < IPV6_MMTU)
|
|
mtu = IPV6_MMTU;
|
|
#endif
|
|
icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu);
|
|
}
|
|
m_freem(m);
|
|
return;
|
|
}
|
|
|
|
if (rt->rt_flags & RTF_GATEWAY)
|
|
dst = (struct sockaddr_in6 *)rt->rt_gateway;
|
|
|
|
/*
|
|
* If we are to forward the packet using the same interface
|
|
* as one we got the packet from, perhaps we should send a redirect
|
|
* to sender to shortcut a hop.
|
|
* Only send redirect if source is sending directly to us,
|
|
* and if packet was not source routed (or has any options).
|
|
* Also, don't send redirect if forwarding using a route
|
|
* modified by a redirect.
|
|
*/
|
|
if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt &&
|
|
#ifdef IPSEC
|
|
!ipsecrt &&
|
|
#endif
|
|
(rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
|
|
if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) != 0) {
|
|
/*
|
|
* If the incoming interface is equal to the outgoing
|
|
* one, and the link attached to the interface is
|
|
* point-to-point, then it will be highly probable
|
|
* that a routing loop occurs. Thus, we immediately
|
|
* drop the packet and send an ICMPv6 error message.
|
|
*
|
|
* type/code is based on suggestion by Rich Draves.
|
|
* not sure if it is the best pick.
|
|
*/
|
|
icmp6_error(mcopy, ICMP6_DST_UNREACH,
|
|
ICMP6_DST_UNREACH_ADDR, 0);
|
|
m_freem(m);
|
|
return;
|
|
}
|
|
type = ND_REDIRECT;
|
|
}
|
|
|
|
/*
|
|
* Check with the firewall...
|
|
*/
|
|
if (ip6_fw_enable && ip6_fw_chk_ptr) {
|
|
u_short port = 0;
|
|
/* If ipfw says divert, we have to just drop packet */
|
|
if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) {
|
|
m_freem(m);
|
|
goto freecopy;
|
|
}
|
|
if (!m)
|
|
goto freecopy;
|
|
}
|
|
|
|
/*
|
|
* Fake scoped addresses. Note that even link-local source or
|
|
* destinaion can appear, if the originating node just sends the
|
|
* packet to us (without address resolution for the destination).
|
|
* Since both icmp6_error and icmp6_redirect_output fill the embedded
|
|
* link identifiers, we can do this stuff after making a copy for
|
|
* returning an error.
|
|
*/
|
|
if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) != 0) {
|
|
/*
|
|
* See corresponding comments in ip6_output.
|
|
* XXX: but is it possible that ip6_forward() sends a packet
|
|
* to a loopback interface? I don't think so, and thus
|
|
* I bark here. (jinmei@kame.net)
|
|
* XXX: it is common to route invalid packets to loopback.
|
|
* also, the codepath will be visited on use of ::1 in
|
|
* rthdr. (itojun)
|
|
*/
|
|
#if 1
|
|
if (0)
|
|
#else
|
|
if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
|
|
#endif
|
|
{
|
|
printf("ip6_forward: outgoing interface is loopback. "
|
|
"src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
|
|
ip6_sprintf(&ip6->ip6_src),
|
|
ip6_sprintf(&ip6->ip6_dst),
|
|
ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
|
|
if_name(rt->rt_ifp));
|
|
}
|
|
|
|
/* we can just use rcvif in forwarding. */
|
|
origifp = m->m_pkthdr.rcvif;
|
|
}
|
|
else
|
|
origifp = rt->rt_ifp;
|
|
/*
|
|
* clear embedded scope identifiers if necessary.
|
|
* in6_clearscope will touch the addresses only when necessary.
|
|
*/
|
|
in6_clearscope(&ip6->ip6_src);
|
|
in6_clearscope(&ip6->ip6_dst);
|
|
|
|
/* Jump over all PFIL processing if hooks are not active. */
|
|
if (inet6_pfil_hook.ph_busy_count == -1)
|
|
goto pass;
|
|
|
|
/* Run through list of hooks for output packets. */
|
|
error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp, PFIL_OUT, NULL);
|
|
if (error != 0)
|
|
goto senderr;
|
|
if (m == NULL)
|
|
goto freecopy;
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
|
|
pass:
|
|
error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
|
|
if (error) {
|
|
in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
|
|
ip6stat.ip6s_cantforward++;
|
|
} else {
|
|
ip6stat.ip6s_forward++;
|
|
in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
|
|
if (type)
|
|
ip6stat.ip6s_redirectsent++;
|
|
else {
|
|
if (mcopy)
|
|
goto freecopy;
|
|
}
|
|
}
|
|
|
|
senderr:
|
|
if (mcopy == NULL)
|
|
return;
|
|
switch (error) {
|
|
case 0:
|
|
if (type == ND_REDIRECT) {
|
|
icmp6_redirect_output(mcopy, rt);
|
|
return;
|
|
}
|
|
goto freecopy;
|
|
|
|
case EMSGSIZE:
|
|
/* xxx MTU is constant in PPP? */
|
|
goto freecopy;
|
|
|
|
case ENOBUFS:
|
|
/* Tell source to slow down like source quench in IP? */
|
|
goto freecopy;
|
|
|
|
case ENETUNREACH: /* shouldn't happen, checked above */
|
|
case EHOSTUNREACH:
|
|
case ENETDOWN:
|
|
case EHOSTDOWN:
|
|
default:
|
|
type = ICMP6_DST_UNREACH;
|
|
code = ICMP6_DST_UNREACH_ADDR;
|
|
break;
|
|
}
|
|
icmp6_error(mcopy, type, code, 0);
|
|
return;
|
|
|
|
freecopy:
|
|
m_freem(mcopy);
|
|
return;
|
|
}
|