NetBSD-5.0.2/sys/netinet6/ip6_forward.c
/* $NetBSD: ip6_forward.c,v 1.65.18.1 2009/11/14 09:48:57 sborrill Exp $ */
/* $KAME: ip6_forward.c,v 1.109 2002/09/11 08:10:17 sakane Exp $ */
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ip6_forward.c,v 1.65.18.1 2009/11/14 09:48:57 sborrill Exp $");
#include "opt_ipsec.h"
#include "opt_pfil_hooks.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/ip6_private.h>
#include <netinet6/scope6_var.h>
#include <netinet/icmp6.h>
#include <netinet6/nd6.h>
#ifdef IPSEC
#include <netinet6/ipsec.h>
#include <netinet6/ipsec_private.h>
#include <netkey/key.h>
#endif /* IPSEC */
#ifdef FAST_IPSEC
#include <netipsec/ipsec.h>
#include <netipsec/ipsec6.h>
#include <netipsec/key.h>
#include <netipsec/xform.h>
#endif /* FAST_IPSEC */
#ifdef PFIL_HOOKS
#include <net/pfil.h>
#endif
#include <net/net_osdep.h>
struct route ip6_forward_rt;
#ifdef PFIL_HOOKS
extern struct pfil_head inet6_pfil_hook; /* XXX */
#endif
/*
* Forward a packet. If some error occurs return the sender
* an icmp packet. Note we can't always generate a meaningful
* icmp message because icmp doesn't have a large enough repertoire
* of codes and types.
*
* If not forwarding, just drop the packet. This could be confusing
* if ipforwarding was zero but some routing protocol was advancing
* us as a gateway to somewhere. However, we must let the routing
* protocol deal with that.
*
*/
void
ip6_forward(struct mbuf *m, int srcrt)
{
struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
const struct sockaddr_in6 *dst;
struct rtentry *rt;
int error = 0, type = 0, code = 0;
struct mbuf *mcopy = NULL;
struct ifnet *origifp; /* maybe unnecessary */
u_int32_t inzone, outzone;
struct in6_addr src_in6, dst_in6;
#ifdef IPSEC
struct secpolicy *sp = NULL;
int ipsecrt = 0;
#endif
#ifdef FAST_IPSEC
struct secpolicy *sp = NULL;
int needipsec = 0;
int s;
#endif
/*
* Clear any in-bound checksum flags for this packet.
*/
m->m_pkthdr.csum_flags = 0;
#ifdef IPSEC
/*
* Check AH/ESP integrity.
*/
/*
* Don't increment ip6s_cantforward because this is the check
* before forwarding packet actually.
*/
if (ipsec6_in_reject(m, NULL)) {
IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO);
m_freem(m);
return;
}
#endif /* IPSEC */
/*
* Do not forward packets to multicast destination (should be handled
* by ip6_mforward().
* Do not forward packets with unspecified source. It was discussed
* in July 2000, on ipngwg mailing list.
*/
if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
IP6_STATINC(IP6_STAT_CANTFORWARD);
/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
if (ip6_log_time + ip6_log_interval < time_second) {
ip6_log_time = time_second;
log(LOG_DEBUG,
"cannot forward "
"from %s to %s nxt %d received on %s\n",
ip6_sprintf(&ip6->ip6_src),
ip6_sprintf(&ip6->ip6_dst),
ip6->ip6_nxt,
if_name(m->m_pkthdr.rcvif));
}
m_freem(m);
return;
}
if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
icmp6_error(m, ICMP6_TIME_EXCEEDED,
ICMP6_TIME_EXCEED_TRANSIT, 0);
return;
}
ip6->ip6_hlim -= IPV6_HLIMDEC;
/*
* Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
* size of IPv6 + ICMPv6 headers) bytes of the packet in case
* we need to generate an ICMP6 message to the src.
* Thanks to M_EXT, in most cases copy will not occur.
*
* It is important to save it before IPsec processing as IPsec
* processing may modify the mbuf.
*/
mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN));
#ifdef IPSEC
/* get a security policy for this packet */
sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
IP_FORWARDING, &error);
if (sp == NULL) {
IPSEC6_STATINC(IPSEC_STAT_OUT_INVAL);
IP6_STATINC(IP6_STAT_CANTFORWARD);
if (mcopy) {
#if 0
/* XXX: what icmp ? */
#else
m_freem(mcopy);
#endif
}
m_freem(m);
return;
}
error = 0;
/* check policy */
switch (sp->policy) {
case IPSEC_POLICY_DISCARD:
/*
* This packet is just discarded.
*/
IPSEC6_STATINC(IPSEC_STAT_OUT_POLVIO);
IP6_STATINC(IP6_STAT_CANTFORWARD);
key_freesp(sp);
if (mcopy) {
#if 0
/* XXX: what icmp ? */
#else
m_freem(mcopy);
#endif
}
m_freem(m);
return;
case IPSEC_POLICY_BYPASS:
case IPSEC_POLICY_NONE:
/* no need to do IPsec. */
key_freesp(sp);
goto skip_ipsec;
case IPSEC_POLICY_IPSEC:
if (sp->req == NULL) {
/* XXX should be panic ? */
printf("ip6_forward: No IPsec request specified.\n");
IP6_STATINC(IP6_STAT_CANTFORWARD);
key_freesp(sp);
if (mcopy) {
#if 0
/* XXX: what icmp ? */
#else
m_freem(mcopy);
#endif
}
m_freem(m);
return;
}
/* do IPsec */
break;
case IPSEC_POLICY_ENTRUST:
default:
/* should be panic ?? */
printf("ip6_forward: Invalid policy found. %d\n", sp->policy);
key_freesp(sp);
goto skip_ipsec;
}
{
struct ipsecrequest *isr = NULL;
struct ipsec_output_state state;
/*
* when the kernel forwards a packet, it is not proper to apply
* IPsec transport mode to the packet is not proper. this check
* avoid from this.
* at present, if there is even a transport mode SA request in the
* security policy, the kernel does not apply IPsec to the packet.
* this check is not enough because the following case is valid.
* ipsec esp/tunnel/xxx-xxx/require esp/transport//require;
*/
for (isr = sp->req; isr; isr = isr->next) {
if (isr->saidx.mode == IPSEC_MODE_ANY)
goto doipsectunnel;
if (isr->saidx.mode == IPSEC_MODE_TUNNEL)
goto doipsectunnel;
}
/*
* if there's no need for tunnel mode IPsec, skip.
*/
if (!isr)
goto skip_ipsec;
doipsectunnel:
/*
* All the extension headers will become inaccessible
* (since they can be encrypted).
* Don't panic, we need no more updates to extension headers
* on inner IPv6 packet (since they are now encapsulated).
*
* IPv6 [ESP|AH] IPv6 [extension headers] payload
*/
bzero(&state, sizeof(state));
state.m = m;
state.ro = NULL; /* update at ipsec6_output_tunnel() */
state.dst = NULL; /* update at ipsec6_output_tunnel() */
error = ipsec6_output_tunnel(&state, sp, 0);
m = state.m;
key_freesp(sp);
if (error) {
/* mbuf is already reclaimed in ipsec6_output_tunnel. */
switch (error) {
case EHOSTUNREACH:
case ENETUNREACH:
case EMSGSIZE:
case ENOBUFS:
case ENOMEM:
break;
default:
printf("ip6_forward (ipsec): error code %d\n", error);
/* FALLTHROUGH */
case ENOENT:
/* don't show these error codes to the user */
break;
}
IP6_STATINC(IP6_STAT_CANTFORWARD);
if (mcopy) {
#if 0
/* XXX: what icmp ? */
#else
m_freem(mcopy);
#endif
}
m_freem(m);
return;
}
if (ip6 != mtod(m, struct ip6_hdr *)) {
/*
* now tunnel mode headers are added. we are originating
* packet instead of forwarding the packet.
*/
ip6_output(m, NULL, NULL, IPV6_FORWARDING/*XXX*/, NULL, NULL,
NULL);
goto freecopy;
}
/* adjust pointer */
rt = state.ro ? rtcache_validate(state.ro) : NULL;
dst = (const struct sockaddr_in6 *)state.dst;
if (dst != NULL && rt != NULL) {
ipsecrt = 1;
goto skip_routing;
}
}
skip_ipsec:
#endif /* IPSEC */
#ifdef FAST_IPSEC
/* Check the security policy (SP) for the packet */
sp = ipsec6_check_policy(m,NULL,0,&needipsec,&error);
if (error != 0) {
/*
* Hack: -EINVAL is used to signal that a packet
* should be silently discarded. This is typically
* because we asked key management for an SA and
* it was delayed (e.g. kicked up to IKE).
*/
if (error == -EINVAL)
error = 0;
goto freecopy;
}
#endif /* FAST_IPSEC */
if (srcrt) {
union {
struct sockaddr dst;
struct sockaddr_in6 dst6;
} u;
sockaddr_in6_init(&u.dst6, &ip6->ip6_dst, 0, 0, 0);
if ((rt = rtcache_lookup(&ip6_forward_rt, &u.dst)) == NULL) {
IP6_STATINC(IP6_STAT_NOROUTE);
/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
if (mcopy) {
icmp6_error(mcopy, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_NOROUTE, 0);
}
m_freem(m);
return;
}
} else if ((rt = rtcache_validate(&ip6_forward_rt)) == NULL &&
(rt = rtcache_update(&ip6_forward_rt, 1)) == NULL) {
/*
* rtcache_getdst(ip6_forward_rt)->sin6_addr was equal to
* ip6->ip6_dst
*/
IP6_STATINC(IP6_STAT_NOROUTE);
/* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */
if (mcopy) {
icmp6_error(mcopy, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_NOROUTE, 0);
}
m_freem(m);
return;
}
dst = satocsin6(rtcache_getdst(&ip6_forward_rt));
#ifdef IPSEC
skip_routing:;
#endif /* IPSEC */
/*
* Source scope check: if a packet can't be delivered to its
* destination for the reason that the destination is beyond the scope
* of the source address, discard the packet and return an icmp6
* destination unreachable error with Code 2 (beyond scope of source
* address). We use a local copy of ip6_src, since in6_setscope()
* will possibly modify its first argument.
* [draft-ietf-ipngwg-icmp-v3-07, Section 3.1]
*/
src_in6 = ip6->ip6_src;
if (in6_setscope(&src_in6, rt->rt_ifp, &outzone)) {
/* XXX: this should not happen */
uint64_t *ip6s = IP6_STAT_GETREF();
ip6s[IP6_STAT_CANTFORWARD]++;
ip6s[IP6_STAT_BADSCOPE]++;
IP6_STAT_PUTREF();
m_freem(m);
return;
}
if (in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone)) {
uint64_t *ip6s = IP6_STAT_GETREF();
ip6s[IP6_STAT_CANTFORWARD]++;
ip6s[IP6_STAT_BADSCOPE]++;
IP6_STAT_PUTREF();
m_freem(m);
return;
}
if (inzone != outzone
#ifdef IPSEC
&& !ipsecrt
#endif
) {
uint64_t *ip6s = IP6_STAT_GETREF();
ip6s[IP6_STAT_CANTFORWARD]++;
ip6s[IP6_STAT_BADSCOPE]++;
IP6_STAT_PUTREF();
in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard);
if (ip6_log_time + ip6_log_interval < time_second) {
ip6_log_time = time_second;
log(LOG_DEBUG,
"cannot forward "
"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));
}
if (mcopy)
icmp6_error(mcopy, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
m_freem(m);
return;
}
#ifdef FAST_IPSEC
/*
* If we need to encapsulate the packet, do it here
* ipsec6_proces_packet will send the packet using ip6_output
*/
if (needipsec) {
s = splsoftnet();
error = ipsec6_process_packet(m,sp->req);
splx(s);
if (mcopy)
goto freecopy;
}
#endif
/*
* Destination scope check: if a packet is going to break the scope
* zone of packet's destination address, discard it. This case should
* usually be prevented by appropriately-configured routing table, but
* we need an explicit check because we may mistakenly forward the
* packet to a different zone by (e.g.) a default route.
*/
dst_in6 = ip6->ip6_dst;
if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
inzone != outzone) {
uint64_t *ip6s = IP6_STAT_GETREF();
ip6s[IP6_STAT_CANTFORWARD]++;
ip6s[IP6_STAT_BADSCOPE]++;
IP6_STAT_PUTREF();
m_freem(m);
return;
}
if (m->m_pkthdr.len > IN6_LINKMTU(rt->rt_ifp)) {
in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig);
if (mcopy) {
u_long mtu;
#ifdef IPSEC
struct secpolicy *xsp;
int ipsecerror;
size_t ipsechdrsiz;
#endif
mtu = IN6_LINKMTU(rt->rt_ifp);
#ifdef IPSEC
/*
* When we do IPsec tunnel ingress, we need to play
* with the link value (decrement IPsec header size
* from mtu value). The code is much simpler than v4
* case, as we have the outgoing interface for
* encapsulated packet as "rt->rt_ifp".
*/
xsp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND,
IP_FORWARDING, &ipsecerror);
if (xsp) {
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 && ip6_sendredirects &&
#ifdef IPSEC
!ipsecrt &&
#endif
(rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) {
if ((rt->rt_ifp->if_flags & IFF_POINTOPOINT) &&
nd6_is_addr_neighbor(
satocsin6(rtcache_getdst(&ip6_forward_rt)),
rt->rt_ifp)) {
/*
* If the incoming interface is equal to the outgoing
* one, the link attached to the interface is
* point-to-point, and the IPv6 destination is
* regarded as on-link on the link, then it will be
* highly probable that the destination address does
* not exist on the link and that the packet is going
* to loop. Thus, we immediately drop the packet and
* send an ICMPv6 error message.
* For other routing loops, we dare to let the packet
* go to the loop, so that a remote diagnosing host
* can detect the loop by traceroute.
* 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;
}
/*
* 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);
#ifdef PFIL_HOOKS
/*
* Run through list of hooks for output packets.
*/
if ((error = pfil_run_hooks(&inet6_pfil_hook, &m, rt->rt_ifp,
PFIL_OUT)) != 0)
goto senderr;
if (m == NULL)
goto freecopy;
ip6 = mtod(m, struct ip6_hdr *);
#endif /* PFIL_HOOKS */
error = nd6_output(rt->rt_ifp, origifp, m, dst, rt);
if (error) {
in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard);
IP6_STATINC(IP6_STAT_CANTFORWARD);
} else {
IP6_STATINC(IP6_STAT_FORWARD);
in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward);
if (type)
IP6_STATINC(IP6_STAT_REDIRECTSENT);
else {
#ifdef GATEWAY
if (m->m_flags & M_CANFASTFWD)
ip6flow_create(&ip6_forward_rt, m);
#endif
if (mcopy)
goto freecopy;
}
}
#ifdef PFIL_HOOKS
senderr:
#endif
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;
}