2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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31 * $KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
38 #include "opt_inet6.h"
39 #include "opt_ipsec.h"
40 #include "opt_ipstealth.h"
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/malloc.h>
47 #include <sys/domain.h>
48 #include <sys/protosw.h>
49 #include <sys/socket.h>
50 #include <sys/errno.h>
52 #include <sys/kernel.h>
53 #include <sys/syslog.h>
56 #include <net/if_var.h>
57 #include <net/if_private.h>
58 #include <net/netisr.h>
59 #include <net/route.h>
60 #include <net/route/nhop.h>
63 #include <netinet/in.h>
64 #include <netinet/in_var.h>
65 #include <netinet/in_systm.h>
66 #include <netinet/ip.h>
67 #include <netinet/ip_var.h>
68 #include <netinet6/in6_var.h>
69 #include <netinet/ip6.h>
70 #include <netinet6/in6_fib.h>
71 #include <netinet6/ip6_var.h>
72 #include <netinet6/scope6_var.h>
73 #include <netinet/icmp6.h>
74 #include <netinet6/nd6.h>
76 #include <netinet/in_pcb.h>
78 #include <netipsec/ipsec_support.h>
81 * Forward a packet. If some error occurs return the sender
82 * an icmp packet. Note we can't always generate a meaningful
83 * icmp message because icmp doesn't have a large enough repertoire
86 * If not forwarding, just drop the packet. This could be confusing
87 * if ipforwarding was zero but some routing protocol was advancing
88 * us as a gateway to somewhere. However, we must let the routing
89 * protocol deal with that.
93 ip6_forward(struct mbuf *m, int srcrt)
95 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
96 struct sockaddr_in6 dst;
97 struct nhop_object *nh = NULL;
98 int error, type = 0, code = 0;
99 struct mbuf *mcopy = NULL;
100 struct ifnet *origifp; /* maybe unnecessary */
101 u_int32_t inzone, outzone;
102 struct in6_addr odst;
103 struct m_tag *fwd_tag;
104 char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
107 * Do not forward packets to multicast destination (should be handled
109 * Do not forward packets with unspecified source. It was discussed
110 * in July 2000, on the ipngwg mailing list.
112 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 ||
113 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
114 IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
115 IP6STAT_INC(ip6s_cantforward);
116 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
117 if (V_ip6_log_cannot_forward && ip6_log_ratelimit()) {
120 "from %s to %s nxt %d received on %s\n",
121 ip6_sprintf(ip6bufs, &ip6->ip6_src),
122 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
124 if_name(m->m_pkthdr.rcvif));
134 ip6->ip6_hlim <= IPV6_HLIMDEC) {
135 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */
136 icmp6_error(m, ICMP6_TIME_EXCEEDED,
137 ICMP6_TIME_EXCEED_TRANSIT, 0);
142 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU -
143 * size of IPv6 + ICMPv6 headers) bytes of the packet in case
144 * we need to generate an ICMP6 message to the src.
145 * Thanks to M_EXT, in most cases copy will not occur.
147 * It is important to save it before IPsec processing as IPsec
148 * processing may modify the mbuf.
150 mcopy = m_copym(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN),
153 if (V_ip6stealth == 0)
155 ip6->ip6_hlim -= IPV6_HLIMDEC;
157 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
158 if (IPSEC_ENABLED(ipv6)) {
159 if ((error = IPSEC_FORWARD(ipv6, m)) != 0) {
160 /* mbuf consumed by IPsec */
162 if (error != EINPROGRESS)
163 IP6STAT_INC(ip6s_cantforward);
166 /* No IPsec processing required */
170 * ip6_forward() operates with IPv6 addresses with deembedded scope.
172 * There are 3 sources of IPv6 destination address:
174 * 1) ip6_input(), where ip6_dst contains deembedded address.
175 * In order to deal with forwarding of link-local packets,
176 * calculate the scope based on input interface (RFC 4007, clause 9).
177 * 2) packet filters changing ip6_dst directly. It would embed scope
178 * for LL addresses, so in6_localip() performs properly.
179 * 3) packet filters attaching PACKET_TAG_IPFORWARD would embed
180 * scope for the nexthop.
182 bzero(&dst, sizeof(struct sockaddr_in6));
183 dst.sin6_family = AF_INET6;
184 dst.sin6_addr = ip6->ip6_dst;
185 dst.sin6_scope_id = in6_get_unicast_scopeid(&ip6->ip6_dst, m->m_pkthdr.rcvif);
187 nh = fib6_lookup(M_GETFIB(m), &dst.sin6_addr, dst.sin6_scope_id,
188 NHR_REF, m->m_pkthdr.flowid);
190 IP6STAT_INC(ip6s_noroute);
191 in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_noroute);
193 icmp6_error(mcopy, ICMP6_DST_UNREACH,
194 ICMP6_DST_UNREACH_NOROUTE, 0);
199 if (nh->nh_flags & (NHF_BLACKHOLE | NHF_REJECT)) {
200 IP6STAT_INC(ip6s_cantforward);
202 if (nh->nh_flags & NHF_REJECT) {
203 icmp6_error(mcopy, ICMP6_DST_UNREACH,
204 ICMP6_DST_UNREACH_REJECT, 0);
212 * Source scope check: if a packet can't be delivered to its
213 * destination for the reason that the destination is beyond the scope
214 * of the source address, discard the packet and return an icmp6
215 * destination unreachable error with Code 2 (beyond scope of source
217 * [draft-ietf-ipngwg-icmp-v3-04.txt, Section 3.1]
219 outzone = in6_get_unicast_scopeid(&ip6->ip6_src, nh->nh_ifp);
220 inzone = in6_get_unicast_scopeid(&ip6->ip6_src, m->m_pkthdr.rcvif);
221 if (inzone != outzone) {
222 IP6STAT_INC(ip6s_cantforward);
223 IP6STAT_INC(ip6s_badscope);
224 in6_ifstat_inc(nh->nh_ifp, ifs6_in_discard);
226 if (V_ip6_log_cannot_forward && ip6_log_ratelimit()) {
229 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
230 ip6_sprintf(ip6bufs, &ip6->ip6_src),
231 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
233 if_name(m->m_pkthdr.rcvif), if_name(nh->nh_ifp));
236 icmp6_error(mcopy, ICMP6_DST_UNREACH,
237 ICMP6_DST_UNREACH_BEYONDSCOPE, 0);
242 * Destination scope check: if a packet is going to break the scope
243 * zone of packet's destination address, discard it. This case should
244 * usually be prevented by appropriately-configured routing table, but
245 * we need an explicit check because we may mistakenly forward the
246 * packet to a different zone by (e.g.) a default route.
248 inzone = in6_get_unicast_scopeid(&ip6->ip6_dst, m->m_pkthdr.rcvif);
249 outzone = in6_get_unicast_scopeid(&ip6->ip6_dst, nh->nh_ifp);
251 if (inzone != outzone) {
252 IP6STAT_INC(ip6s_cantforward);
253 IP6STAT_INC(ip6s_badscope);
257 if (nh->nh_flags & NHF_GATEWAY) {
258 /* Store gateway address in deembedded form */
259 dst.sin6_addr = nh->gw6_sa.sin6_addr;
260 dst.sin6_scope_id = ntohs(in6_getscope(&dst.sin6_addr));
261 in6_clearscope(&dst.sin6_addr);
265 * If we are to forward the packet using the same interface
266 * as one we got the packet from, perhaps we should send a redirect
267 * to sender to shortcut a hop.
268 * Only send redirect if source is sending directly to us,
269 * and if packet was not source routed (or has any options).
270 * Also, don't send redirect if forwarding using a route
271 * modified by a redirect.
273 if (V_ip6_sendredirects && nh->nh_ifp == m->m_pkthdr.rcvif && !srcrt &&
274 (nh->nh_flags & NHF_REDIRECT) == 0)
278 * Fake scoped addresses. Note that even link-local source or
279 * destinaion can appear, if the originating node just sends the
280 * packet to us (without address resolution for the destination).
281 * Since both icmp6_error and icmp6_redirect_output fill the embedded
282 * link identifiers, we can do this stuff after making a copy for
283 * returning an error.
285 if ((nh->nh_ifp->if_flags & IFF_LOOPBACK) != 0) {
287 * See corresponding comments in ip6_output.
288 * XXX: but is it possible that ip6_forward() sends a packet
289 * to a loopback interface? I don't think so, and thus
290 * I bark here. (jinmei@kame.net)
291 * XXX: it is common to route invalid packets to loopback.
292 * also, the codepath will be visited on use of ::1 in
298 if ((rt->rt_flags & (RTF_BLACKHOLE|RTF_REJECT)) == 0)
301 printf("ip6_forward: outgoing interface is loopback. "
302 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n",
303 ip6_sprintf(ip6bufs, &ip6->ip6_src),
304 ip6_sprintf(ip6bufd, &ip6->ip6_dst),
305 ip6->ip6_nxt, if_name(m->m_pkthdr.rcvif),
306 if_name(nh->nh_ifp));
309 /* we can just use rcvif in forwarding. */
310 origifp = m->m_pkthdr.rcvif;
313 origifp = nh->nh_ifp;
315 * clear embedded scope identifiers if necessary.
316 * in6_clearscope will touch the addresses only when necessary.
318 in6_clearscope(&ip6->ip6_src);
319 in6_clearscope(&ip6->ip6_dst);
321 /* Jump over all PFIL processing if hooks are not active. */
322 if (!PFIL_HOOKED_OUT(V_inet6_pfil_head))
326 /* Run through list of hooks for forwarded packets. */
327 if (pfil_mbuf_fwd(V_inet6_pfil_head, &m, nh->nh_ifp,
330 ip6 = mtod(m, struct ip6_hdr *);
332 /* See if destination IP address was changed by packet filter. */
333 if (!IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst)) {
334 m->m_flags |= M_SKIP_FIREWALL;
335 /* If destination is now ourself drop to ip6_input(). */
336 if (in6_localip(&ip6->ip6_dst))
337 m->m_flags |= M_FASTFWD_OURS;
341 /* Update address and scopeid. Assume scope is embedded */
342 dst.sin6_scope_id = ntohs(in6_getscope(&ip6->ip6_dst));
343 dst.sin6_addr = ip6->ip6_dst;
344 in6_clearscope(&dst.sin6_addr);
345 goto again; /* Redo the routing table lookup. */
349 /* See if local, if yes, send it to netisr. */
350 if (m->m_flags & M_FASTFWD_OURS) {
351 if (m->m_pkthdr.rcvif == NULL)
352 m->m_pkthdr.rcvif = V_loif;
353 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
354 m->m_pkthdr.csum_flags |=
355 CSUM_DATA_VALID_IPV6 | CSUM_PSEUDO_HDR;
356 m->m_pkthdr.csum_data = 0xffff;
358 #if defined(SCTP) || defined(SCTP_SUPPORT)
359 if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6)
360 m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
362 error = netisr_queue(NETISR_IPV6, m);
365 /* Or forward to some other address? */
366 if ((m->m_flags & M_IP6_NEXTHOP) &&
367 (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
368 struct sockaddr_in6 *gw6 = (struct sockaddr_in6 *)(fwd_tag + 1);
370 /* Update address and scopeid. Assume scope is embedded */
371 dst.sin6_scope_id = ntohs(in6_getscope(&gw6->sin6_addr));
372 dst.sin6_addr = gw6->sin6_addr;
373 in6_clearscope(&dst.sin6_addr);
375 m->m_flags |= M_SKIP_FIREWALL;
376 m->m_flags &= ~M_IP6_NEXTHOP;
377 m_tag_delete(m, fwd_tag);
383 /* See if the size was changed by the packet filter. */
384 /* TODO: change to nh->nh_mtu */
385 if (m->m_pkthdr.len > IN6_LINKMTU(nh->nh_ifp)) {
386 in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig);
388 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0,
389 IN6_LINKMTU(nh->nh_ifp));
393 /* Currently LLE layer stores embedded IPv6 addresses */
394 if (IN6_IS_SCOPE_LINKLOCAL(&dst.sin6_addr)) {
395 in6_set_unicast_scopeid(&dst.sin6_addr, dst.sin6_scope_id);
396 dst.sin6_scope_id = 0;
398 error = nd6_output_ifp(nh->nh_ifp, origifp, m, &dst, NULL);
400 in6_ifstat_inc(nh->nh_ifp, ifs6_out_discard);
401 IP6STAT_INC(ip6s_cantforward);
403 IP6STAT_INC(ip6s_forward);
404 in6_ifstat_inc(nh->nh_ifp, ifs6_out_forward);
406 IP6STAT_INC(ip6s_redirectsent);
417 if (type == ND_REDIRECT) {
418 icmp6_redirect_output(mcopy, nh);
424 /* xxx MTU is constant in PPP? */
428 /* Tell source to slow down like source quench in IP? */
431 case ENETUNREACH: /* shouldn't happen, checked above */
436 type = ICMP6_DST_UNREACH;
437 code = ICMP6_DST_UNREACH_ADDR;
440 icmp6_error(mcopy, type, code, 0);