ip6_input.c

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		/*
		 * record address information into m_aux.
		 */
		(void)ip6_setdstifaddr(m, ia6);

		/*
		 * packets to a tentative, duplicated, or somehow invalid
		 * address must not be accepted.
		 */
		if (!(ia6->ia6_flags & IN6_IFF_NOTREADY)) {
			/* this address is ready */
			ours = 1;
			deliverifp = ia6->ia_ifp;	/* correct? */
#if defined(__FreeBSD__) && __FreeBSD__ >= 4
			/* Count the packet in the ip address stats */
			ia6->ia_ifa.if_ipackets++;
			ia6->ia_ifa.if_ibytes += m->m_pkthdr.len;
#elif defined(__bsdi__) && _BSDI_VERSION >= 199802
			/* Count the packet in the ip address stats */
			ia6->ia_ifa.ifa_ipackets++;
			ia6->ia_ifa.ifa_ibytes += m->m_pkthdr.len;
#endif
			goto hbhcheck;
		} else {
			/* address is not ready, so discard the packet. */
			nd6log((LOG_INFO,
			    "ip6_input: packet to an unready address %s->%s\n",
			    ip6_sprintf(&ip6->ip6_src),
			    ip6_sprintf(&ip6->ip6_dst)));
			goto bad;
		}
	}
	} /* XXX indentation (see above) */

#ifdef MEASURE_PERFORMANCE
	/* we detected that packet is not ours thru the basic algorithm */
	ctr_end = read_tsc();
#ifdef MEASURE_PERFORMANCE_UDPONLY
	if (ip6->ip6_nxt == IPPROTO_UDP)
#else
	if (1)
#endif
		add_performance_log(ctr_end - ctr_beg, &ip6->ip6_dst);
#endif

	/*
	 * FAITH(Firewall Aided Internet Translator)
	 */
#if defined(NFAITH) && 0 < NFAITH
	if (ip6_keepfaith) {
		if (ip6_forward_rt.ro_rt && ip6_forward_rt.ro_rt->rt_ifp
		 && ip6_forward_rt.ro_rt->rt_ifp->if_type == IFT_FAITH) {
			/* XXX do we need more sanity checks? */
			ours = 1;
			deliverifp = ip6_forward_rt.ro_rt->rt_ifp; /* faith */
			goto hbhcheck;
		}
	}
#endif

#ifdef NATPT
	/*
	 * NAT-PT (Network Address Translation - Protocol Translation)
	 */
	if (ip6_protocol_tr) {
		struct mbuf *m1 = NULL;

		switch (natpt_in6(m, &m1)) {
		case IPPROTO_IP:
			goto processpacket;
		case IPPROTO_IPV4:
			ip_forward(m1, 0);
			break;
		case IPPROTO_IPV6:
			ip6_forward(m1, 0);
			break;
		case IPPROTO_MAX:		/* discard this packet	*/
		default:
			break;
		case IPPROTO_DONE:		/* discard without free	*/
			return;
		}

		if (m != m1)
			m_freem(m);

		return;
	}

 processpacket:
#endif

#if 0
    {
	/*
	 * Last resort: check in6_ifaddr for incoming interface.
	 * The code is here until I update the "goto ours hack" code above
	 * working right.
	 */
	struct ifaddr *ifa;
	for (ifa = m->m_pkthdr.rcvif->if_addrlist.tqh_first;
	     ifa;
	     ifa = ifa->ifa_list.tqe_next) {
		if (ifa->ifa_addr == NULL)
			continue;	/* just for safety */
		if (ifa->ifa_addr->sa_family != AF_INET6)
			continue;
		if (IN6_ARE_ADDR_EQUAL(IFA_IN6(ifa), &ip6->ip6_dst)) {
			ours = 1;
			deliverifp = ifa->ifa_ifp;
			goto hbhcheck;
		}
	}
    }
#endif

	/*
	 * Now there is no reason to process the packet if it's not our own
	 * and we're not a router.
	 */
	if (!ip6_forwarding) {
		ip6stat.ip6s_cantforward++;
		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
                log(LOG_FAIL, "%s.%d\n", __FUNCTION__, __LINE__);
		goto bad;
	}

 hbhcheck:
	/*
	 * record address information into m_aux, if we don't have one yet.
	 * note that we are unable to record it, if the address is not listed
	 * as our interface address (e.g. multicast addresses, addresses
	 * within FAITH prefixes and such).
	 */
	if (deliverifp && !ip6_getdstifaddr(m)) {
		struct in6_ifaddr *ia6;

		ia6 = in6_ifawithifp(deliverifp, &ip6->ip6_dst);
		if (ia6) {
			if (!ip6_setdstifaddr(m, ia6)) {
				/*
				 * XXX maybe we should drop the packet here,
				 * as we could not provide enough information
				 * to the upper layers.
				 */
			}
		}
	}

	/*
	 * Process Hop-by-Hop options header if it's contained.
	 * m may be modified in ip6_hopopts_input().
	 * If a JumboPayload option is included, plen will also be modified.
	 */
	plen = (u_int32_t)ntohs(ip6->ip6_plen);
	if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
		struct ip6_hbh *hbh;

		if (ip6_hopopts_input(&plen, &rtalert, &m, &off)) {
#if 0	/*touches NULL pointer*/
			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
#endif
			return;	/* m have already been freed */
		}

		/* adjust pointer */
		ip6 = mtod(m, struct ip6_hdr *);

		/*
		 * if the payload length field is 0 and the next header field
		 * indicates Hop-by-Hop Options header, then a Jumbo Payload
		 * option MUST be included.
		 */
		if (ip6->ip6_plen == 0 && plen == 0) {
			/*
			 * Note that if a valid jumbo payload option is
			 * contained, ip6_hoptops_input() must set a valid
			 * (non-zero) payload length to the variable plen. 
			 */
			ip6stat.ip6s_badoptions++;
			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
			icmp6_error(m, ICMP6_PARAM_PROB,
				    ICMP6_PARAMPROB_HEADER,
				    (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
			return;
		}
#ifndef PULLDOWN_TEST
		/* ip6_hopopts_input() ensures that mbuf is contiguous */
		hbh = (struct ip6_hbh *)(ip6 + 1);
#else
		IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
			sizeof(struct ip6_hbh));
		if (hbh == NULL) {
			ip6stat.ip6s_tooshort++;
			return;
		}
#endif
		nxt = hbh->ip6h_nxt;

		/*
		 * accept the packet if a router alert option is included
		 * and we act as an IPv6 router.
		 */
		if (rtalert != ~0 && ip6_forwarding)
			ours = 1;
	} else
		nxt = ip6->ip6_nxt;

	/*
	 * Check that the amount of data in the buffers
	 * is as at least much as the IPv6 header would have us expect.
	 * Trim mbufs if longer than we expect.
	 * Drop packet if shorter than we expect.
	 */
	if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
		ip6stat.ip6s_tooshort++;
		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
		goto bad;
	}
	if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
		if (m->m_len == m->m_pkthdr.len) {
			m->m_len = sizeof(struct ip6_hdr) + plen;
			m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
		} else
			m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
	}

	/*
	 * Forward if desirable.
	 */
	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
		/*
		 * If we are acting as a multicast router, all
		 * incoming multicast packets are passed to the
		 * kernel-level multicast forwarding function.
		 * The packet is returned (relatively) intact; if
		 * ip6_mforward() returns a non-zero value, the packet
		 * must be discarded, else it may be accepted below.
		 */
		if (ip6_mrouter && ip6_mforward(ip6, m->m_pkthdr.rcvif, m)) {
			ip6stat.ip6s_cantforward++;
			m_freem(m);
			return;
		}
		if (!ours) {
			m_freem(m);
			return;
		}
	} else if (!ours) {
		ip6_forward(m, 0);
		return;
	}	

	ip6 = mtod(m, struct ip6_hdr *);

	/*
	 * Malicious party may be able to use IPv4 mapped addr to confuse
	 * tcp/udp stack and bypass security checks (act as if it was from
	 * 127.0.0.1 by using IPv6 src ::ffff:127.0.0.1).  Be cautious.
	 *
	 * For SIIT end node behavior, you may want to disable the check.
	 * However, you will  become vulnerable to attacks using IPv4 mapped
	 * source.
	 */
	if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
	    IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
		ip6stat.ip6s_badscope++;
		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
                log(LOG_FAIL, "%s.%d\n", __FUNCTION__, __LINE__);
		goto bad;
	}

	/*
	 * Tell launch routine the next header
	 */
#if defined(__NetBSD__) && defined(IFA_STATS)
	if (deliverifp != NULL) {
		struct in6_ifaddr *ia6;
		ia6 = in6_ifawithifp(deliverifp, &ip6->ip6_dst);
		if (ia6)
			ia6->ia_ifa.ifa_data.ifad_inbytes += m->m_pkthdr.len;
	}
#endif
	ip6stat.ip6s_delivered++;
	in6_ifstat_inc(deliverifp, ifs6_in_deliver);
	nest = 0;

	while (nxt != IPPROTO_DONE) {
		if (ip6_hdrnestlimit && (++nest > ip6_hdrnestlimit)) {
			ip6stat.ip6s_toomanyhdr++;
                        log(LOG_FAIL, "%s.%d\n", __FUNCTION__, __LINE__);
			goto bad;
		}

		/*
		 * protection against faulty packet - there should be
		 * more sanity checks in header chain processing.
		 */
		if (m->m_pkthdr.len < off) {
			ip6stat.ip6s_tooshort++;
			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
                        log(LOG_FAIL, "%s.%d\n", __FUNCTION__, __LINE__);
			goto bad;
		}

#if 0
		/*
		 * do we need to do it for every header?  yeah, other
		 * functions can play with it (like re-allocate and copy).
		 */
		mhist = ip6_addaux(m);
		if (mhist && M_TRAILINGSPACE(mhist) >= sizeof(nxt)) {
			hist = mtod(mhist, caddr_t) + mhist->m_len;
			bcopy(&nxt, hist, sizeof(nxt));
			mhist->m_len += sizeof(nxt);
		} else {
			ip6stat.ip6s_toomanyhdr++;
                        log(LOG_FAIL, "%s.%d\n", __FUNCTION__, __LINE__);
			goto bad;
		}
#endif

#if defined(IPSEC) && !defined(__OpenBSD__)
		/*
		 * enforce IPsec policy checking if we are seeing last header.
		 * note that we do not visit this with protocols with pcb layer
		 * code - like udp/tcp/raw ip.
		 */
		if ((inet6sw[ip6_protox[nxt]].pr_flags & PR_LASTHDR) != 0 &&
		    ipsec6_in_reject(m, NULL)) {
			ipsec6stat.in_polvio++;
			goto bad;
		}
#endif
#ifdef MIP6
		/*
		 * XXX
		 * check if the packet was tunneled after all extion
		 * headers have been processed.  get from Ericsson
		 * code.  need more consideration.
		 */
		if ((nxt != IPPROTO_HOPOPTS) && (nxt != IPPROTO_DSTOPTS) &&
		    (nxt != IPPROTO_ROUTING) && (nxt != IPPROTO_FRAGMENT) &&
		    (nxt != IPPROTO_ESP) && (nxt != IPPROTO_AH)) {
			if (mip6_route_optimize(m))
				goto bad;
		}
#endif /* MIP6 */		
		nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
	}
	return;
 bad:
	m_freem(m);
}

/*
 * set/grab in6_ifaddr correspond to IPv6 destination address.
 * XXX backward compatibility wrapper
 */
static struct mbuf *
ip6_setdstifaddr(m, ia6)
	struct mbuf *m;
	struct in6_ifaddr *ia6;
{
	struct mbuf *n;

	n = ip6_addaux(m);
	if (n)
		mtod(n, struct ip6aux *)->ip6a_dstia6 = ia6;
	return n;	/* NULL if failed to set */
}

struct in6_ifaddr *
ip6_getdstifaddr(m)
	struct mbuf *m;
{
	struct mbuf *n;

	n = ip6_findaux(m);
	if (n)
		return mtod(n, struct ip6aux *)->ip6a_dstia6;
	else
		return NULL;
}

/*
 * Hop-by-Hop options header processing. If a valid jumbo payload option is
 * included, the real payload length will be stored in plenp.
 */
static int
ip6_hopopts_input(plenp, rtalertp, mp, offp)
	u_int32_t *plenp;
	u_int32_t *rtalertp;	/* XXX: should be stored more smart way */
	struct mbuf **mp;
	int *offp;
{
	struct mbuf *m = *mp;
	int off = *offp, hbhlen;
	struct ip6_hbh *hbh;
	u_int8_t *opt;

	/* validation of the length of the header */
#ifndef PULLDOWN_TEST
	IP6_EXTHDR_CHECK(m, off, sizeof(*hbh), -1);
	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
	hbhlen = (hbh->ip6h_len + 1) << 3;

	IP6_EXTHDR_CHECK(m, off, hbhlen, -1);
	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
#else
	IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m,
		sizeof(struct ip6_hdr), sizeof(struct ip6_hbh));
	if (hbh == NULL) {
		ip6stat.ip6s_tooshort++;
		return -1;
	}
	hbhlen = (hbh->ip6h_len + 1) << 3;
	IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
		hbhlen);
	if (hbh == NULL) {
		ip6stat.ip6s_tooshort++;
		return -1;
	}
#endif
	off += hbhlen;
	hbhlen -= sizeof(struct ip6_hbh);
	opt = (u_int8_t *)hbh + sizeof(struct ip6_hbh);

	if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
				hbhlen, rtalertp, plenp) < 0)
		return(-1);

	*offp = off;
	*mp = m;
	return(0);
}

/*
 * Search header for all Hop-by-hop options and process each option.
 * This function is separate from ip6_hopopts_input() in order to
 * handle a case where the sending node itself process its hop-by-hop
 * options header. In such a case, the function is called from ip6_output().
 *
 * The function assumes that hbh header is located right after the IPv6 header
 * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
 * opthead + hbhlen is located in continuous memory region.
 */
int
ip6_process_hopopts(m, opthead, hbhlen, rtalertp, plenp)
	struct mbuf *m;
	u_int8_t *opthead;
	int hbhlen;
	u_int32_t *rtalertp;
	u_int32_t *plenp;
{
	struct ip6_hdr *ip6;
	int optlen = 0;
	u_int8_t *opt = opthead;
	u_int16_t rtalert_val;
	u_int32_t jumboplen;
	const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);

	for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
		switch (*opt) {
		case IP6OPT_PAD1:
			optlen = 1;
			break;
		case IP6OPT_PADN:
			if (hbhlen < IP6OPT_MINLEN) {
				ip6stat.ip6s_toosmall++;
				goto bad;
			}
			optlen = *(opt + 1) + 2;
			break;
		case IP6OPT_RTALERT:
			/* XXX may need check for alignment */
			if (hbhlen < IP6OPT_RTALERT_LEN) {
				ip6stat.ip6s_toosmall++;
				goto bad;
			}
			if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
				/* XXX stat */