/*
* Destination options header processing.
*/
int
dest6_input(struct mbuf **mp, int *offp, int proto)
{
struct mbuf *m = *mp;
int off = *offp, dstoptlen, optlen;
struct ip6_dest *dstopts;
u_int8_t *opt;
/* validation of the length of the header */
IP6_EXTHDR_GET(dstopts, struct ip6_dest *, m, off, sizeof(*dstopts));
if (dstopts == NULL)
return IPPROTO_DONE;
dstoptlen = (dstopts->ip6d_len + 1) << 3;
IP6_EXTHDR_GET(dstopts, struct ip6_dest *, m, off, dstoptlen);
if (dstopts == NULL)
return IPPROTO_DONE;
off += dstoptlen;
dstoptlen -= sizeof(struct ip6_dest);
opt = (u_int8_t *)dstopts + sizeof(struct ip6_dest);
/* search header for all options. */
for (optlen = 0; dstoptlen > 0; dstoptlen -= optlen, opt += optlen) {
if (*opt != IP6OPT_PAD1 &&
(dstoptlen < IP6OPT_MINLEN || *(opt + 1) + 2 > dstoptlen)) {
IP6_STATINC(IP6_STAT_TOOSMALL);
goto bad;
}
switch (*opt) {
case IP6OPT_PAD1:
optlen = 1;
break;
case IP6OPT_PADN:
optlen = *(opt + 1) + 2;
break;
default: /* unknown option */
optlen = ip6_unknown_opt(opt, m,
opt - mtod(m, u_int8_t *));
if (optlen == -1)
return (IPPROTO_DONE);
optlen += 2;
break;
}
}
*offp = off;
return (dstopts->ip6d_nxt);
bad:
m_freem(m);
return (IPPROTO_DONE);
}
int
route6_input(struct mbuf **mp, int *offp, int proto)
{
struct ip6_hdr *ip6;
struct mbuf *m = *mp;
struct ip6_rthdr *rh;
int off = *offp, rhlen;
ip6 = mtod(m, struct ip6_hdr *);
IP6_EXTHDR_GET(rh, struct ip6_rthdr *, m, off, sizeof(*rh));
if (rh == NULL) {
IP6_STATINC(IP6_STAT_TOOSHORT);
return IPPROTO_DONE;
}
switch (rh->ip6r_type) {
#if 0
/*
* See http://www.secdev.org/conf/IPv6_RH_security-csw07.pdf
* for why IPV6_RTHDR_TYPE_0 is banned here.
*
* We return ICMPv6 parameter problem so that innocent people
* (not an attacker) would notice about the use of IPV6_RTHDR_TYPE_0.
* Since there's no amplification, and ICMPv6 error will be rate-
* controlled, it shouldn't cause any problem.
* If you are concerned about this, you may want to use the following
* code fragment:
*
* case IPV6_RTHDR_TYPE_0:
* m_freem(m);
* return (IPPROTO_DONE);
*/
case IPV6_RTHDR_TYPE_0:
rhlen = (rh->ip6r_len + 1) << 3;
/*
* note on option length:
* maximum rhlen: 2048
* max mbuf m_pulldown can handle: MCLBYTES == usually 2048
* so, here we are assuming that m_pulldown can handle
* rhlen == 2048 case. this may not be a good thing to
* assume - we may want to avoid pulling it up altogether.
*/
IP6_EXTHDR_GET(rh, struct ip6_rthdr *, m, off, rhlen);
if (rh == NULL) {
IP6_STATINC(IP6_STAT_TOOSHORT);
return IPPROTO_DONE;
}
if (ip6_rthdr0(m, ip6, (struct ip6_rthdr0 *)rh))
return (IPPROTO_DONE);
break;
#endif
default:
/* unknown routing type */
if (rh->ip6r_segleft == 0) {
rhlen = (rh->ip6r_len + 1) << 3;
break; /* Final dst. Just ignore the header. */
}
IP6_STATINC(IP6_STAT_BADOPTIONS);
icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
(char *)&rh->ip6r_type - (char *)ip6);
return (IPPROTO_DONE);
}
*offp += rhlen;
return (rh->ip6r_nxt);
}
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 */
uint32_t inzone, outzone;
struct in6_addr src_in6, dst_in6;
#ifdef IPSEC
int needipsec = 0;
struct secpolicy *sp = NULL;
#endif
/*
* Clear any in-bound checksum flags for this packet.
*/
m->m_pkthdr.csum_flags = 0;
/*
* 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_cantforward(ip6, m->m_pkthdr.rcvif, NULL,
((m->m_flags & (M_BCAST|M_MCAST)) != 0) ? "bcast/mcast" :
IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ? "mcast/dst" :
"unspec/src");
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
if (ipsec_used) {
/* 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 /* 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));
/*
* 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;
inzone = outzone = ~0;
if (in6_setscope(&src_in6, rt->rt_ifp, &outzone) != 0 ||
in6_setscope(&src_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
inzone != outzone) {
ip6_cantforward(ip6, m->m_pkthdr.rcvif, rt->rt_ifp,
"src[%s] inzone %d outzone %d",
in6_getscopename(&ip6->ip6_src), inzone, outzone);
if (mcopy)
icmp6_error(mcopy, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
m_freem(m);
return;
}
#ifdef IPSEC
/*
* If we need to encapsulate the packet, do it here
* ipsec6_proces_packet will send the packet using ip6_output
*/
if (needipsec) {
int 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;
inzone = outzone = ~0;
if (in6_setscope(&dst_in6, m->m_pkthdr.rcvif, &inzone) != 0 ||
in6_setscope(&dst_in6, rt->rt_ifp, &outzone) != 0 ||
inzone != outzone) {
ip6_cantforward(ip6, m->m_pkthdr.rcvif, rt->rt_ifp,
"dst[%s] inzone %d outzone %d",
in6_getscopename(&ip6->ip6_dst), inzone, outzone);
if (mcopy)
icmp6_error(mcopy, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
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;
mtu = IN6_LINKMTU(rt->rt_ifp);
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 &&
(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. ([email protected])
* 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);
/*
* 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 *);
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;
}
}
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;
}
/*
* Type0 routing header processing
*
* RFC2292 backward compatibility warning: no support for strict/loose bitmap,
* as it was dropped between RFC1883 and RFC2460.
*/
static int
ip6_rthdr0(struct mbuf *m, struct ip6_hdr *ip6,
struct ip6_rthdr0 *rh0)
{
int addrs, index;
struct in6_addr *nextaddr, tmpaddr;
const struct ip6aux *ip6a;
if (rh0->ip6r0_segleft == 0)
return (0);
if (rh0->ip6r0_len % 2
#ifdef COMPAT_RFC1883
|| rh0->ip6r0_len > 46
#endif
) {
/*
* Type 0 routing header can't contain more than 23 addresses.
* RFC 2462: this limitation was removed since strict/loose
* bitmap field was deleted.
*/
IP6_STATINC(IP6_STAT_BADOPTIONS);
icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
(char *)&rh0->ip6r0_len - (char *)ip6);
return (-1);
}
if ((addrs = rh0->ip6r0_len / 2) < rh0->ip6r0_segleft) {
IP6_STATINC(IP6_STAT_BADOPTIONS);
icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
(char *)&rh0->ip6r0_segleft - (char *)ip6);
return (-1);
}
index = addrs - rh0->ip6r0_segleft;
rh0->ip6r0_segleft--;
nextaddr = ((struct in6_addr *)(rh0 + 1)) + index;
/*
* reject invalid addresses. be proactive about malicious use of
* IPv4 mapped/compat address.
* XXX need more checks?
*/
if (IN6_IS_ADDR_MULTICAST(nextaddr) ||
IN6_IS_ADDR_UNSPECIFIED(nextaddr) ||
IN6_IS_ADDR_V4MAPPED(nextaddr) ||
IN6_IS_ADDR_V4COMPAT(nextaddr)) {
p6stat[IP6_STAT_BADOPTIONS]++;
goto bad;
}
if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst) ||
IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst) ||
IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
IP6_STATINC(IP6_STAT_BADOPTIONS);
goto bad;
}
/*
* Determine the scope zone of the next hop, based on the interface
* of the current hop. [RFC4007, Section 9]
* Then disambiguate the scope zone for the next hop (if necessary).
*/
if ((ip6a = ip6_getdstifaddr(m)) == NULL)
goto bad;
if (in6_setzoneid(nextaddr, ip6a->ip6a_scope_id) != 0) {
IP6_STATINC(IP6_STAT_BADSCOPE);
goto bad;
}
/*
* Swap the IPv6 destination address and nextaddr. Forward the packet.
*/
tmpaddr = *nextaddr;
*nextaddr = ip6->ip6_dst;
in6_clearscope(nextaddr); /* XXX */
ip6->ip6_dst = tmpaddr;
#ifdef COMPAT_RFC1883
if (rh0->ip6r0_slmap[index / 8] & (1 << (7 - (index % 8))))
ip6_forward(m, IPV6_SRCRT_NEIGHBOR);
else
ip6_forward(m, IPV6_SRCRT_NOTNEIGHBOR);
#else
ip6_forward(m, 1);
#endif
return (-1); /* m would be freed in ip6_forward() */
bad:
m_freem(m);
return (-1);
}