2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
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13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
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17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
34 * $FreeBSD: src/sys/netinet/ip_icmp.c,v 1.39.2.19 2003/01/24 05:11:34 sam Exp $
35 * $DragonFly: src/sys/netinet/ip_icmp.c,v 1.5 2003/08/23 11:18:00 rob Exp $
38 #include "opt_ipsec.h"
40 #include <sys/param.h>
41 #include <sys/systm.h>
43 #include <sys/protosw.h>
44 #include <sys/socket.h>
46 #include <sys/kernel.h>
47 #include <sys/sysctl.h>
50 #include <net/if_types.h>
51 #include <net/route.h>
54 #include <netinet/in.h>
55 #include <netinet/in_systm.h>
56 #include <netinet/in_var.h>
57 #include <netinet/ip.h>
58 #include <netinet/ip_icmp.h>
59 #include <netinet/ip_var.h>
60 #include <netinet/icmp_var.h>
63 #include <netinet6/ipsec.h>
64 #include <netproto/key/key.h>
68 #include <netipsec/ipsec.h>
69 #include <netipsec/key.h>
74 * ICMP routines: error generation, receive packet processing, and
75 * routines to turnaround packets back to the originator, and
76 * host table maintenance routines.
79 static struct icmpstat icmpstat;
80 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
81 &icmpstat, icmpstat, "");
83 static int icmpmaskrepl = 0;
84 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
85 &icmpmaskrepl, 0, "");
87 static int drop_redirect = 0;
88 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
89 &drop_redirect, 0, "");
91 static int log_redirect = 0;
92 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
93 &log_redirect, 0, "");
98 * ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl
99 * variable content is -1 and read-only.
102 static int icmplim = 200;
103 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
107 static int icmplim = -1;
108 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD,
113 static int icmplim_output = 1;
114 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
115 &icmplim_output, 0, "");
118 * ICMP broadcast echo sysctl
121 static int icmpbmcastecho = 0;
122 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
123 &icmpbmcastecho, 0, "");
130 static void icmp_reflect (struct mbuf *);
131 static void icmp_send (struct mbuf *, struct mbuf *, struct route *);
132 static int ip_next_mtu (int, int);
134 extern struct protosw inetsw[];
137 * Generate an error packet of type error
138 * in response to bad packet ip.
141 icmp_error(n, type, code, dest, destifp)
145 struct ifnet *destifp;
147 struct ip *oip = mtod(n, struct ip *), *nip;
148 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
155 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
157 if (type != ICMP_REDIRECT)
158 icmpstat.icps_error++;
160 * Don't send error if not the first fragment of message.
161 * Don't error if the old packet protocol was ICMP
162 * error message, only known informational types.
164 if (oip->ip_off &~ (IP_MF|IP_DF))
166 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
167 n->m_len >= oiplen + ICMP_MINLEN &&
168 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
169 icmpstat.icps_oldicmp++;
172 /* Don't send error in response to a multicast or broadcast packet */
173 if (n->m_flags & (M_BCAST|M_MCAST))
176 * First, formulate icmp message
178 m = m_gethdr(M_DONTWAIT, MT_HEADER);
181 icmplen = min(oiplen + 8, oip->ip_len);
182 if (icmplen < sizeof(struct ip))
183 panic("icmp_error: bad length");
184 m->m_len = icmplen + ICMP_MINLEN;
185 MH_ALIGN(m, m->m_len);
186 icp = mtod(m, struct icmp *);
187 if ((u_int)type > ICMP_MAXTYPE)
189 icmpstat.icps_outhist[type]++;
190 icp->icmp_type = type;
191 if (type == ICMP_REDIRECT)
192 icp->icmp_gwaddr.s_addr = dest;
196 * The following assignments assume an overlay with the
197 * zeroed icmp_void field.
199 if (type == ICMP_PARAMPROB) {
200 icp->icmp_pptr = code;
202 } else if (type == ICMP_UNREACH &&
203 code == ICMP_UNREACH_NEEDFRAG && destifp) {
204 icp->icmp_nextmtu = htons(destifp->if_mtu);
208 icp->icmp_code = code;
209 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
213 * Convert fields to network representation.
219 * Now, copy old ip header (without options)
220 * in front of icmp message.
222 if (m->m_data - sizeof(struct ip) < m->m_pktdat)
224 m->m_data -= sizeof(struct ip);
225 m->m_len += sizeof(struct ip);
226 m->m_pkthdr.len = m->m_len;
227 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
228 nip = mtod(m, struct ip *);
229 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
230 nip->ip_len = m->m_len;
231 nip->ip_vhl = IP_VHL_BORING;
232 nip->ip_p = IPPROTO_ICMP;
240 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
241 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
242 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
245 * Process a received ICMP message.
248 icmp_input(m, off, proto)
254 struct ip *ip = mtod(m, struct ip *);
255 int icmplen = ip->ip_len;
257 struct in_ifaddr *ia;
258 void (*ctlfunc) (int, struct sockaddr *, void *);
262 * Locate icmp structure in mbuf, and check
263 * that not corrupted and of at least minimum length.
267 char buf[4 * sizeof "123"];
268 strcpy(buf, inet_ntoa(ip->ip_src));
269 printf("icmp_input from %s to %s, len %d\n",
270 buf, inet_ntoa(ip->ip_dst), icmplen);
273 if (icmplen < ICMP_MINLEN) {
274 icmpstat.icps_tooshort++;
277 i = hlen + min(icmplen, ICMP_ADVLENMIN);
278 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
279 icmpstat.icps_tooshort++;
282 ip = mtod(m, struct ip *);
285 icp = mtod(m, struct icmp *);
286 if (in_cksum(m, icmplen)) {
287 icmpstat.icps_checksum++;
293 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
295 * Deliver very specific ICMP type only.
297 switch (icp->icmp_type) {
308 printf("icmp_input, type %d code %d\n", icp->icmp_type,
313 * Message type specific processing.
315 if (icp->icmp_type > ICMP_MAXTYPE)
317 icmpstat.icps_inhist[icp->icmp_type]++;
318 code = icp->icmp_code;
319 switch (icp->icmp_type) {
323 case ICMP_UNREACH_NET:
324 case ICMP_UNREACH_HOST:
325 case ICMP_UNREACH_SRCFAIL:
326 case ICMP_UNREACH_NET_UNKNOWN:
327 case ICMP_UNREACH_HOST_UNKNOWN:
328 case ICMP_UNREACH_ISOLATED:
329 case ICMP_UNREACH_TOSNET:
330 case ICMP_UNREACH_TOSHOST:
331 case ICMP_UNREACH_HOST_PRECEDENCE:
332 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
333 code = PRC_UNREACH_NET;
336 case ICMP_UNREACH_NEEDFRAG:
341 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
342 * Treat subcodes 2,3 as immediate RST
344 case ICMP_UNREACH_PROTOCOL:
345 case ICMP_UNREACH_PORT:
346 code = PRC_UNREACH_PORT;
349 case ICMP_UNREACH_NET_PROHIB:
350 case ICMP_UNREACH_HOST_PROHIB:
351 case ICMP_UNREACH_FILTER_PROHIB:
352 code = PRC_UNREACH_ADMIN_PROHIB;
363 code += PRC_TIMXCEED_INTRANS;
369 code = PRC_PARAMPROB;
372 case ICMP_SOURCEQUENCH:
378 * Problem with datagram; advise higher level routines.
380 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
381 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
382 icmpstat.icps_badlen++;
385 NTOHS(icp->icmp_ip.ip_len);
386 /* Discard ICMP's in response to multicast packets */
387 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
391 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
393 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
397 * If we got a needfrag and there is a host route to the
398 * original destination, and the MTU is not locked, then
399 * set the MTU in the route to the suggested new value
400 * (if given) and then notify as usual. The ULPs will
401 * notice that the MTU has changed and adapt accordingly.
402 * If no new MTU was suggested, then we guess a new one
403 * less than the current value. If the new MTU is
404 * unreasonably small (arbitrarily set at 296), then
405 * we reset the MTU to the interface value and enable the
406 * lock bit, indicating that we are no longer doing MTU
409 if (code == PRC_MSGSIZE) {
413 rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
414 RTF_CLONING | RTF_PRCLONING);
415 if (rt && (rt->rt_flags & RTF_HOST)
416 && !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
417 mtu = ntohs(icp->icmp_nextmtu);
419 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
422 printf("MTU for %s reduced to %d\n",
423 inet_ntoa(icmpsrc.sin_addr), mtu);
426 /* rt->rt_rmx.rmx_mtu =
427 rt->rt_ifp->if_mtu; */
428 rt->rt_rmx.rmx_locks |= RTV_MTU;
429 } else if (rt->rt_rmx.rmx_mtu > mtu) {
430 rt->rt_rmx.rmx_mtu = mtu;
439 * XXX if the packet contains [IPv4 AH TCP], we can't make a
440 * notification to TCP layer.
442 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
444 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
445 (void *)&icp->icmp_ip);
449 icmpstat.icps_badcode++;
454 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
455 icmpstat.icps_bmcastecho++;
458 icp->icmp_type = ICMP_ECHOREPLY;
460 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
468 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
469 icmpstat.icps_bmcasttstamp++;
472 if (icmplen < ICMP_TSLEN) {
473 icmpstat.icps_badlen++;
476 icp->icmp_type = ICMP_TSTAMPREPLY;
477 icp->icmp_rtime = iptime();
478 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
480 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
487 if (icmpmaskrepl == 0)
490 * We are not able to respond with all ones broadcast
491 * unless we receive it over a point-to-point interface.
493 if (icmplen < ICMP_MASKLEN)
495 switch (ip->ip_dst.s_addr) {
497 case INADDR_BROADCAST:
499 icmpdst.sin_addr = ip->ip_src;
503 icmpdst.sin_addr = ip->ip_dst;
505 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
506 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
511 icp->icmp_type = ICMP_MASKREPLY;
512 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
513 if (ip->ip_src.s_addr == 0) {
514 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
515 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
516 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
517 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
520 ip->ip_len += hlen; /* since ip_input deducts this */
521 icmpstat.icps_reflect++;
522 icmpstat.icps_outhist[icp->icmp_type]++;
530 src = ntohl(ip->ip_src.s_addr);
531 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
532 gw = ntohl(icp->icmp_gwaddr.s_addr);
533 printf("icmp redirect from %d.%d.%d.%d: "
534 "%d.%d.%d.%d => %d.%d.%d.%d\n",
535 (int)(src >> 24), (int)((src >> 16) & 0xff),
536 (int)((src >> 8) & 0xff), (int)(src & 0xff),
537 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
538 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
539 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
540 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
546 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
547 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
548 icmpstat.icps_badlen++;
552 * Short circuit routing redirects to force
553 * immediate change in the kernel's routing
554 * tables. The message is also handed to anyone
555 * listening on a raw socket (e.g. the routing
556 * daemon for use in updating its tables).
558 icmpgw.sin_addr = ip->ip_src;
559 icmpdst.sin_addr = icp->icmp_gwaddr;
562 char buf[4 * sizeof "123"];
563 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
565 printf("redirect dst %s to %s\n",
566 buf, inet_ntoa(icp->icmp_gwaddr));
569 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
570 rtredirect((struct sockaddr *)&icmpsrc,
571 (struct sockaddr *)&icmpdst,
572 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
573 (struct sockaddr *)&icmpgw, (struct rtentry **)0);
574 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
576 key_sa_routechange((struct sockaddr *)&icmpsrc);
581 * No kernel processing for the following;
582 * just fall through to send to raw listener.
585 case ICMP_ROUTERADVERT:
586 case ICMP_ROUTERSOLICIT:
587 case ICMP_TSTAMPREPLY:
595 rip_input(m, off, proto);
603 * Reflect the ip packet back to the source
609 struct ip *ip = mtod(m, struct ip *);
611 struct in_ifaddr *ia;
613 struct mbuf *opts = 0;
614 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
615 struct route *ro = NULL, rt;
617 if (!in_canforward(ip->ip_src) &&
618 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
619 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
620 m_freem(m); /* Bad return address */
621 icmpstat.icps_badaddr++;
622 goto done; /* Ip_output() will check for broadcast */
625 ip->ip_dst = ip->ip_src;
627 bzero(ro, sizeof(*ro));
629 * If the incoming packet was addressed directly to us,
630 * use dst as the src for the reply. Otherwise (broadcast
631 * or anonymous), use the address which corresponds
632 * to the incoming interface.
634 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
635 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
637 if (m->m_pkthdr.rcvif != NULL &&
638 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
639 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
640 if (ifa->ifa_addr->sa_family != AF_INET)
643 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
648 ia = ip_rtaddr(ip->ip_dst, ro);
649 /* We need a route to do anything useful. */
652 icmpstat.icps_noroute++;
656 t = IA_SIN(ia)->sin_addr;
658 ip->ip_ttl = ip_defttl;
666 * Retrieve any source routing from the incoming packet;
667 * add on any record-route or timestamp options.
669 cp = (u_char *) (ip + 1);
670 if ((opts = ip_srcroute()) == 0 &&
671 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
672 opts->m_len = sizeof(struct in_addr);
673 mtod(opts, struct in_addr *)->s_addr = 0;
678 printf("icmp_reflect optlen %d rt %d => ",
679 optlen, opts->m_len);
681 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
682 opt = cp[IPOPT_OPTVAL];
683 if (opt == IPOPT_EOL)
685 if (opt == IPOPT_NOP)
688 if (cnt < IPOPT_OLEN + sizeof(*cp))
690 len = cp[IPOPT_OLEN];
691 if (len < IPOPT_OLEN + sizeof(*cp) ||
696 * Should check for overflow, but it "can't happen"
698 if (opt == IPOPT_RR || opt == IPOPT_TS ||
699 opt == IPOPT_SECURITY) {
701 mtod(opts, caddr_t) + opts->m_len, len);
705 /* Terminate & pad, if necessary */
706 cnt = opts->m_len % 4;
708 for (; cnt < 4; cnt++) {
709 *(mtod(opts, caddr_t) + opts->m_len) =
716 printf("%d\n", opts->m_len);
720 * Now strip out original options by copying rest of first
721 * mbuf's data back, and adjust the IP length.
723 ip->ip_len -= optlen;
724 ip->ip_vhl = IP_VHL_BORING;
726 if (m->m_flags & M_PKTHDR)
727 m->m_pkthdr.len -= optlen;
728 optlen += sizeof(struct ip);
729 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
730 (unsigned)(m->m_len - sizeof(struct ip)));
732 m->m_flags &= ~(M_BCAST|M_MCAST);
733 icmp_send(m, opts, ro);
742 * Send an icmp packet back to the ip level,
743 * after supplying a checksum.
746 icmp_send(m, opts, rt)
751 struct ip *ip = mtod(m, struct ip *);
755 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
758 icp = mtod(m, struct icmp *);
760 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
763 m->m_pkthdr.rcvif = (struct ifnet *)0;
766 char buf[4 * sizeof "123"];
767 strcpy(buf, inet_ntoa(ip->ip_dst));
768 printf("icmp_send dst %s src %s\n",
769 buf, inet_ntoa(ip->ip_src));
772 (void) ip_output(m, opts, rt, 0, NULL, NULL);
782 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
788 * Return the next larger or smaller MTU plateau (table from RFC 1191)
789 * given current value MTU. If DIR is less than zero, a larger plateau
790 * is returned; otherwise, a smaller value is returned.
793 ip_next_mtu(mtu, dir)
797 static int mtutab[] = {
798 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
803 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
804 if (mtu >= mtutab[i])
812 return mtutab[i - 1];
815 if (mtutab[i] == 0) {
817 } else if(mtu > mtutab[i]) {
820 return mtutab[i + 1];
829 * badport_bandlim() - check for ICMP bandwidth limit
831 * Return 0 if it is ok to send an ICMP error response, -1 if we have
832 * hit our bandwidth limit and it is not ok.
834 * If icmplim is <= 0, the feature is disabled and 0 is returned.
836 * For now we separate the TCP and UDP subsystems w/ different 'which'
837 * values. We may eventually remove this separation (and simplify the
840 * Note that the printing of the error message is delayed so we can
841 * properly print the icmp error rate that the system was trying to do
842 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
843 * the 'final' error, but it doesn't make sense to solve the printing
844 * delay with more complex code.
848 badport_bandlim(int which)
850 static int lticks[BANDLIM_MAX + 1];
851 static int lpackets[BANDLIM_MAX + 1];
853 const char *bandlimittype[] = {
854 "Limiting icmp unreach response",
855 "Limiting icmp ping response",
856 "Limiting icmp tstamp response",
857 "Limiting closed port RST response",
858 "Limiting open port RST response"
862 * Return ok status if feature disabled or argument out of
866 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0)
868 dticks = ticks - lticks[which];
871 * reset stats when cumulative dt exceeds one second.
874 if ((unsigned int)dticks > hz) {
875 if (lpackets[which] > icmplim && icmplim_output) {
876 printf("%s from %d to %d packets per second\n",
877 bandlimittype[which],
882 lticks[which] = ticks;
890 if (++lpackets[which] > icmplim) {