This is in preparation for enabling a loadable SCTP stack. Analogous to IPSEC/IPSEC_SUPPORT, the SCTP_SUPPORT kernel option must be configured in order to support a loadable SCTP implementation. Discussed with: tuexen MFC after: 2 weeks Sponsored by: The FreeBSD Foundation
457 lines
14 KiB
C
457 lines
14 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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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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* $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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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 "opt_sctp.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/if_var.h>
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#include <net/netisr.h>
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#include <net/route.h>
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#include <net/route/nhop.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/in6_fib.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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#include <netipsec/ipsec_support.h>
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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(struct mbuf *m, 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;
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struct nhop_object *nh = 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 odst;
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struct m_tag *fwd_tag;
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char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
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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_INC(ip6s_cantforward);
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/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
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if (V_ip6_log_time + V_ip6_log_interval < time_uptime) {
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V_ip6_log_time = time_uptime;
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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(ip6bufs, &ip6->ip6_src),
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ip6_sprintf(ip6bufd, &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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if (
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#ifdef IPSTEALTH
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V_ip6stealth == 0 &&
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#endif
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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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/*
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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_copym(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN),
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M_NOWAIT);
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#ifdef IPSTEALTH
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if (V_ip6stealth == 0)
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#endif
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ip6->ip6_hlim -= IPV6_HLIMDEC;
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#if defined(IPSEC) || defined(IPSEC_SUPPORT)
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if (IPSEC_ENABLED(ipv6)) {
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if ((error = IPSEC_FORWARD(ipv6, m)) != 0) {
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/* mbuf consumed by IPsec */
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m_freem(mcopy);
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if (error != EINPROGRESS)
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IP6STAT_INC(ip6s_cantforward);
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return;
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}
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/* No IPsec processing required */
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}
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#endif
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/*
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* ip6_forward() operates with IPv6 addresses with deembedded scope.
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*
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* There are 3 sources of IPv6 destination address:
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*
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* 1) ip6_input(), where ip6_dst contains deembedded address.
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* In order to deal with forwarding of link-local packets,
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* calculate the scope based on input interface (RFC 4007, clause 9).
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* 2) packet filters changing ip6_dst directly. It would embed scope
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* for LL addresses, so in6_localip() performs properly.
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* 3) packet filters attaching PACKET_TAG_IPFORWARD would embed
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* scope for the nexthop.
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*/
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bzero(&dst, 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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dst.sin6_scope_id = in6_get_unicast_scopeid(&ip6->ip6_dst, m->m_pkthdr.rcvif);
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again:
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nh = fib6_lookup(M_GETFIB(m), &dst.sin6_addr, dst.sin6_scope_id,
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NHR_REF, m->m_pkthdr.flowid);
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if (nh == NULL) {
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IP6STAT_INC(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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goto bad;
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}
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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).
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* [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
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*/
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outzone = in6_get_unicast_scopeid(&ip6->ip6_src, nh->nh_ifp);
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inzone = in6_get_unicast_scopeid(&ip6->ip6_src, m->m_pkthdr.rcvif);
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if (inzone != outzone) {
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IP6STAT_INC(ip6s_cantforward);
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IP6STAT_INC(ip6s_badscope);
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in6_ifstat_inc(nh->nh_ifp, ifs6_in_discard);
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if (V_ip6_log_time + V_ip6_log_interval < time_uptime) {
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V_ip6_log_time = time_uptime;
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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(ip6bufs, &ip6->ip6_src),
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ip6_sprintf(ip6bufd, &ip6->ip6_dst),
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ip6->ip6_nxt,
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if_name(m->m_pkthdr.rcvif), if_name(nh->nh_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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goto bad;
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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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inzone = in6_get_unicast_scopeid(&ip6->ip6_dst, m->m_pkthdr.rcvif);
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outzone = in6_get_unicast_scopeid(&ip6->ip6_dst, nh->nh_ifp);
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if (inzone != outzone) {
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IP6STAT_INC(ip6s_cantforward);
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IP6STAT_INC(ip6s_badscope);
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goto bad;
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}
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if (nh->nh_flags & NHF_GATEWAY) {
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/* Store gateway address in deembedded form */
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dst.sin6_addr = nh->gw6_sa.sin6_addr;
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dst.sin6_scope_id = ntohs(in6_getscope(&dst.sin6_addr));
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in6_clearscope(&dst.sin6_addr);
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}
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/*
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* If we are to forward the packet using the same interface
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* as one we got the packet from, perhaps we should send a redirect
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* to sender to shortcut a hop.
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* Only send redirect if source is sending directly to us,
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* and if packet was not source routed (or has any options).
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* Also, don't send redirect if forwarding using a route
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* modified by a redirect.
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*/
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if (V_ip6_sendredirects && nh->nh_ifp == m->m_pkthdr.rcvif && !srcrt &&
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(nh->nh_flags & NHF_REDIRECT) == 0) {
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if ((nh->nh_ifp->if_flags & IFF_POINTOPOINT) != 0) {
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/*
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* If the incoming interface is equal to the outgoing
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* one, and the link attached to the interface is
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* point-to-point, then it will be highly probable
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* that a routing loop occurs. Thus, we immediately
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* drop the packet and send an ICMPv6 error message.
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*
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* type/code is based on suggestion by Rich Draves.
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* not sure if it is the best pick.
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*/
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icmp6_error(mcopy, ICMP6_DST_UNREACH,
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ICMP6_DST_UNREACH_ADDR, 0);
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goto bad;
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}
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type = ND_REDIRECT;
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}
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/*
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* Fake scoped addresses. Note that even link-local source or
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* destinaion can appear, if the originating node just sends the
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* packet to us (without address resolution for the destination).
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* Since both icmp6_error and icmp6_redirect_output fill the embedded
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* link identifiers, we can do this stuff after making a copy for
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* returning an error.
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*/
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if ((nh->nh_ifp->if_flags & IFF_LOOPBACK) != 0) {
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/*
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* See corresponding comments in ip6_output.
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* XXX: but is it possible that ip6_forward() sends a packet
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* to a loopback interface? I don't think so, and thus
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* I bark here. (jinmei@kame.net)
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* XXX: it is common to route invalid packets to loopback.
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* also, the codepath will be visited on use of ::1 in
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* rthdr. (itojun)
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*/
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#if 1
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if (0)
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#else
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if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
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#endif
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{
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printf("ip6_forward: outgoing interface is loopback. "
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"src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
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ip6_sprintf(ip6bufs, &ip6->ip6_src),
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ip6_sprintf(ip6bufd, &ip6->ip6_dst),
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ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
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if_name(nh->nh_ifp));
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}
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/* we can just use rcvif in forwarding. */
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origifp = m->m_pkthdr.rcvif;
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}
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else
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origifp = nh->nh_ifp;
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/*
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* clear embedded scope identifiers if necessary.
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* in6_clearscope will touch the addresses only when necessary.
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*/
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in6_clearscope(&ip6->ip6_src);
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in6_clearscope(&ip6->ip6_dst);
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/* Jump over all PFIL processing if hooks are not active. */
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if (!PFIL_HOOKED_OUT(V_inet6_pfil_head))
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goto pass;
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odst = ip6->ip6_dst;
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/* Run through list of hooks for forwarded packets. */
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if (pfil_run_hooks(V_inet6_pfil_head, &m, nh->nh_ifp, PFIL_OUT |
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PFIL_FWD, NULL) != PFIL_PASS)
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goto freecopy;
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ip6 = mtod(m, struct ip6_hdr *);
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/* See if destination IP address was changed by packet filter. */
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if (!IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst)) {
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m->m_flags |= M_SKIP_FIREWALL;
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/* If destination is now ourself drop to ip6_input(). */
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if (in6_localip(&ip6->ip6_dst))
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m->m_flags |= M_FASTFWD_OURS;
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else {
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NH_FREE(nh);
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/* Update address and scopeid. Assume scope is embedded */
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dst.sin6_scope_id = ntohs(in6_getscope(&ip6->ip6_dst));
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dst.sin6_addr = ip6->ip6_dst;
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in6_clearscope(&dst.sin6_addr);
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goto again; /* Redo the routing table lookup. */
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}
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}
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/* See if local, if yes, send it to netisr. */
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if (m->m_flags & M_FASTFWD_OURS) {
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if (m->m_pkthdr.rcvif == NULL)
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m->m_pkthdr.rcvif = V_loif;
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if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
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m->m_pkthdr.csum_flags |=
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CSUM_DATA_VALID_IPV6 | CSUM_PSEUDO_HDR;
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m->m_pkthdr.csum_data = 0xffff;
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}
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#if defined(SCTP) || defined(SCTP_SUPPORT)
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if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6)
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m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
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#endif
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error = netisr_queue(NETISR_IPV6, m);
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goto out;
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}
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/* Or forward to some other address? */
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if ((m->m_flags & M_IP6_NEXTHOP) &&
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(fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
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struct sockaddr_in6 *gw6 = (struct sockaddr_in6 *)(fwd_tag + 1);
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/* Update address and scopeid. Assume scope is embedded */
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dst.sin6_scope_id = ntohs(in6_getscope(&gw6->sin6_addr));
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dst.sin6_addr = gw6->sin6_addr;
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in6_clearscope(&dst.sin6_addr);
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m->m_flags |= M_SKIP_FIREWALL;
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m->m_flags &= ~M_IP6_NEXTHOP;
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m_tag_delete(m, fwd_tag);
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NH_FREE(nh);
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goto again;
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}
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pass:
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/* See if the size was changed by the packet filter. */
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/* TODO: change to nh->nh_mtu */
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if (m->m_pkthdr.len > IN6_LINKMTU(nh->nh_ifp)) {
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in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig);
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if (mcopy)
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icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0,
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IN6_LINKMTU(nh->nh_ifp));
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goto bad;
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}
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/* Currently LLE layer stores embedded IPv6 addresses */
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if (IN6_IS_SCOPE_LINKLOCAL(&dst.sin6_addr)) {
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in6_set_unicast_scopeid(&dst.sin6_addr, dst.sin6_scope_id);
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dst.sin6_scope_id = 0;
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}
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error = nd6_output_ifp(nh->nh_ifp, origifp, m, &dst, NULL);
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if (error) {
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in6_ifstat_inc(nh->nh_ifp, ifs6_out_discard);
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IP6STAT_INC(ip6s_cantforward);
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} else {
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IP6STAT_INC(ip6s_forward);
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in6_ifstat_inc(nh->nh_ifp, ifs6_out_forward);
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if (type)
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IP6STAT_INC(ip6s_redirectsent);
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else {
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if (mcopy)
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goto freecopy;
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}
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}
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if (mcopy == NULL)
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goto out;
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switch (error) {
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case 0:
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if (type == ND_REDIRECT) {
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icmp6_redirect_output(mcopy, nh);
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goto out;
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}
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goto freecopy;
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case EMSGSIZE:
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/* xxx MTU is constant in PPP? */
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goto freecopy;
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case ENOBUFS:
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/* Tell source to slow down like source quench in IP? */
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goto freecopy;
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|
|
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);
|
|
goto out;
|
|
|
|
freecopy:
|
|
m_freem(mcopy);
|
|
goto out;
|
|
bad:
|
|
m_freem(m);
|
|
out:
|
|
if (nh != NULL)
|
|
NH_FREE(nh);
|
|
}
|