2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
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6 * modification, are permitted provided that the following conditions
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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.
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24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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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 1.7 2004/02/14 21:12:39 dillon 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>
48 #include <sys/in_cksum.h>
51 #include <net/if_types.h>
52 #include <net/route.h>
55 #include <netinet/in.h>
56 #include <netinet/in_systm.h>
57 #include <netinet/in_var.h>
58 #include <netinet/ip.h>
59 #include <netinet/ip_icmp.h>
60 #include <netinet/ip_var.h>
61 #include <netinet/icmp_var.h>
64 #include <netinet6/ipsec.h>
65 #include <netproto/key/key.h>
69 #include <netipsec/ipsec.h>
70 #include <netipsec/key.h>
75 * ICMP routines: error generation, receive packet processing, and
76 * routines to turnaround packets back to the originator, and
77 * host table maintenance routines.
80 static struct icmpstat icmpstat;
81 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
82 &icmpstat, icmpstat, "");
84 static int icmpmaskrepl = 0;
85 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
86 &icmpmaskrepl, 0, "");
88 static int drop_redirect = 0;
89 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
90 &drop_redirect, 0, "");
92 static int log_redirect = 0;
93 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
94 &log_redirect, 0, "");
99 * ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl
100 * variable content is -1 and read-only.
103 static int icmplim = 200;
104 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
108 static int icmplim = -1;
109 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD,
114 static int icmplim_output = 1;
115 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
116 &icmplim_output, 0, "");
119 * ICMP broadcast echo sysctl
122 static int icmpbmcastecho = 0;
123 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
124 &icmpbmcastecho, 0, "");
131 static void icmp_reflect (struct mbuf *);
132 static void icmp_send (struct mbuf *, struct mbuf *, struct route *);
133 static int ip_next_mtu (int, int);
135 extern struct protosw inetsw[];
138 * Generate an error packet of type error
139 * in response to bad packet ip.
142 icmp_error(n, type, code, dest, destifp)
146 struct ifnet *destifp;
148 struct ip *oip = mtod(n, struct ip *), *nip;
149 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
156 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
158 if (type != ICMP_REDIRECT)
159 icmpstat.icps_error++;
161 * Don't send error if not the first fragment of message.
162 * Don't error if the old packet protocol was ICMP
163 * error message, only known informational types.
165 if (oip->ip_off &~ (IP_MF|IP_DF))
167 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
168 n->m_len >= oiplen + ICMP_MINLEN &&
169 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
170 icmpstat.icps_oldicmp++;
173 /* Don't send error in response to a multicast or broadcast packet */
174 if (n->m_flags & (M_BCAST|M_MCAST))
177 * First, formulate icmp message
179 m = m_gethdr(M_DONTWAIT, MT_HEADER);
182 icmplen = min(oiplen + 8, oip->ip_len);
183 if (icmplen < sizeof(struct ip))
184 panic("icmp_error: bad length");
185 m->m_len = icmplen + ICMP_MINLEN;
186 MH_ALIGN(m, m->m_len);
187 icp = mtod(m, struct icmp *);
188 if ((u_int)type > ICMP_MAXTYPE)
190 icmpstat.icps_outhist[type]++;
191 icp->icmp_type = type;
192 if (type == ICMP_REDIRECT)
193 icp->icmp_gwaddr.s_addr = dest;
197 * The following assignments assume an overlay with the
198 * zeroed icmp_void field.
200 if (type == ICMP_PARAMPROB) {
201 icp->icmp_pptr = code;
203 } else if (type == ICMP_UNREACH &&
204 code == ICMP_UNREACH_NEEDFRAG && destifp) {
205 icp->icmp_nextmtu = htons(destifp->if_mtu);
209 icp->icmp_code = code;
210 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
214 * Convert fields to network representation.
220 * Now, copy old ip header (without options)
221 * in front of icmp message.
223 if (m->m_data - sizeof(struct ip) < m->m_pktdat)
225 m->m_data -= sizeof(struct ip);
226 m->m_len += sizeof(struct ip);
227 m->m_pkthdr.len = m->m_len;
228 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
229 nip = mtod(m, struct ip *);
230 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
231 nip->ip_len = m->m_len;
232 nip->ip_vhl = IP_VHL_BORING;
233 nip->ip_p = IPPROTO_ICMP;
241 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
242 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
243 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
246 * Process a received ICMP message.
249 icmp_input(m, off, proto)
255 struct ip *ip = mtod(m, struct ip *);
256 int icmplen = ip->ip_len;
258 struct in_ifaddr *ia;
259 void (*ctlfunc) (int, struct sockaddr *, void *);
263 * Locate icmp structure in mbuf, and check
264 * that not corrupted and of at least minimum length.
268 char buf[4 * sizeof "123"];
269 strcpy(buf, inet_ntoa(ip->ip_src));
270 printf("icmp_input from %s to %s, len %d\n",
271 buf, inet_ntoa(ip->ip_dst), icmplen);
274 if (icmplen < ICMP_MINLEN) {
275 icmpstat.icps_tooshort++;
278 i = hlen + min(icmplen, ICMP_ADVLENMIN);
279 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
280 icmpstat.icps_tooshort++;
283 ip = mtod(m, struct ip *);
286 icp = mtod(m, struct icmp *);
287 if (in_cksum(m, icmplen)) {
288 icmpstat.icps_checksum++;
294 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
296 * Deliver very specific ICMP type only.
298 switch (icp->icmp_type) {
309 printf("icmp_input, type %d code %d\n", icp->icmp_type,
314 * Message type specific processing.
316 if (icp->icmp_type > ICMP_MAXTYPE)
318 icmpstat.icps_inhist[icp->icmp_type]++;
319 code = icp->icmp_code;
320 switch (icp->icmp_type) {
324 case ICMP_UNREACH_NET:
325 case ICMP_UNREACH_HOST:
326 case ICMP_UNREACH_SRCFAIL:
327 case ICMP_UNREACH_NET_UNKNOWN:
328 case ICMP_UNREACH_HOST_UNKNOWN:
329 case ICMP_UNREACH_ISOLATED:
330 case ICMP_UNREACH_TOSNET:
331 case ICMP_UNREACH_TOSHOST:
332 case ICMP_UNREACH_HOST_PRECEDENCE:
333 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
334 code = PRC_UNREACH_NET;
337 case ICMP_UNREACH_NEEDFRAG:
342 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
343 * Treat subcodes 2,3 as immediate RST
345 case ICMP_UNREACH_PROTOCOL:
346 case ICMP_UNREACH_PORT:
347 code = PRC_UNREACH_PORT;
350 case ICMP_UNREACH_NET_PROHIB:
351 case ICMP_UNREACH_HOST_PROHIB:
352 case ICMP_UNREACH_FILTER_PROHIB:
353 code = PRC_UNREACH_ADMIN_PROHIB;
364 code += PRC_TIMXCEED_INTRANS;
370 code = PRC_PARAMPROB;
373 case ICMP_SOURCEQUENCH:
379 * Problem with datagram; advise higher level routines.
381 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
382 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
383 icmpstat.icps_badlen++;
386 NTOHS(icp->icmp_ip.ip_len);
387 /* Discard ICMP's in response to multicast packets */
388 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
392 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
394 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
398 * If we got a needfrag and there is a host route to the
399 * original destination, and the MTU is not locked, then
400 * set the MTU in the route to the suggested new value
401 * (if given) and then notify as usual. The ULPs will
402 * notice that the MTU has changed and adapt accordingly.
403 * If no new MTU was suggested, then we guess a new one
404 * less than the current value. If the new MTU is
405 * unreasonably small (arbitrarily set at 296), then
406 * we reset the MTU to the interface value and enable the
407 * lock bit, indicating that we are no longer doing MTU
410 if (code == PRC_MSGSIZE) {
414 rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
415 RTF_CLONING | RTF_PRCLONING);
416 if (rt && (rt->rt_flags & RTF_HOST)
417 && !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
418 mtu = ntohs(icp->icmp_nextmtu);
420 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
423 printf("MTU for %s reduced to %d\n",
424 inet_ntoa(icmpsrc.sin_addr), mtu);
427 /* rt->rt_rmx.rmx_mtu =
428 rt->rt_ifp->if_mtu; */
429 rt->rt_rmx.rmx_locks |= RTV_MTU;
430 } else if (rt->rt_rmx.rmx_mtu > mtu) {
431 rt->rt_rmx.rmx_mtu = mtu;
440 * XXX if the packet contains [IPv4 AH TCP], we can't make a
441 * notification to TCP layer.
443 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
445 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
446 (void *)&icp->icmp_ip);
450 icmpstat.icps_badcode++;
455 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
456 icmpstat.icps_bmcastecho++;
459 icp->icmp_type = ICMP_ECHOREPLY;
461 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
469 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
470 icmpstat.icps_bmcasttstamp++;
473 if (icmplen < ICMP_TSLEN) {
474 icmpstat.icps_badlen++;
477 icp->icmp_type = ICMP_TSTAMPREPLY;
478 icp->icmp_rtime = iptime();
479 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
481 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
488 if (icmpmaskrepl == 0)
491 * We are not able to respond with all ones broadcast
492 * unless we receive it over a point-to-point interface.
494 if (icmplen < ICMP_MASKLEN)
496 switch (ip->ip_dst.s_addr) {
498 case INADDR_BROADCAST:
500 icmpdst.sin_addr = ip->ip_src;
504 icmpdst.sin_addr = ip->ip_dst;
506 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
507 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
512 icp->icmp_type = ICMP_MASKREPLY;
513 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
514 if (ip->ip_src.s_addr == 0) {
515 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
516 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
517 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
518 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
521 ip->ip_len += hlen; /* since ip_input deducts this */
522 icmpstat.icps_reflect++;
523 icmpstat.icps_outhist[icp->icmp_type]++;
531 src = ntohl(ip->ip_src.s_addr);
532 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
533 gw = ntohl(icp->icmp_gwaddr.s_addr);
534 printf("icmp redirect from %d.%d.%d.%d: "
535 "%d.%d.%d.%d => %d.%d.%d.%d\n",
536 (int)(src >> 24), (int)((src >> 16) & 0xff),
537 (int)((src >> 8) & 0xff), (int)(src & 0xff),
538 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
539 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
540 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
541 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
547 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
548 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
549 icmpstat.icps_badlen++;
553 * Short circuit routing redirects to force
554 * immediate change in the kernel's routing
555 * tables. The message is also handed to anyone
556 * listening on a raw socket (e.g. the routing
557 * daemon for use in updating its tables).
559 icmpgw.sin_addr = ip->ip_src;
560 icmpdst.sin_addr = icp->icmp_gwaddr;
563 char buf[4 * sizeof "123"];
564 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
566 printf("redirect dst %s to %s\n",
567 buf, inet_ntoa(icp->icmp_gwaddr));
570 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
571 rtredirect((struct sockaddr *)&icmpsrc,
572 (struct sockaddr *)&icmpdst,
573 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
574 (struct sockaddr *)&icmpgw, (struct rtentry **)0);
575 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
577 key_sa_routechange((struct sockaddr *)&icmpsrc);
582 * No kernel processing for the following;
583 * just fall through to send to raw listener.
586 case ICMP_ROUTERADVERT:
587 case ICMP_ROUTERSOLICIT:
588 case ICMP_TSTAMPREPLY:
596 rip_input(m, off, proto);
604 * Reflect the ip packet back to the source
610 struct ip *ip = mtod(m, struct ip *);
612 struct in_ifaddr *ia;
614 struct mbuf *opts = 0;
615 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
616 struct route *ro = NULL, rt;
618 if (!in_canforward(ip->ip_src) &&
619 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
620 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
621 m_freem(m); /* Bad return address */
622 icmpstat.icps_badaddr++;
623 goto done; /* Ip_output() will check for broadcast */
626 ip->ip_dst = ip->ip_src;
628 bzero(ro, sizeof(*ro));
630 * If the incoming packet was addressed directly to us,
631 * use dst as the src for the reply. Otherwise (broadcast
632 * or anonymous), use the address which corresponds
633 * to the incoming interface.
635 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
636 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
638 if (m->m_pkthdr.rcvif != NULL &&
639 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
640 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
641 if (ifa->ifa_addr->sa_family != AF_INET)
644 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
649 ia = ip_rtaddr(ip->ip_dst, ro);
650 /* We need a route to do anything useful. */
653 icmpstat.icps_noroute++;
657 t = IA_SIN(ia)->sin_addr;
659 ip->ip_ttl = ip_defttl;
667 * Retrieve any source routing from the incoming packet;
668 * add on any record-route or timestamp options.
670 cp = (u_char *) (ip + 1);
671 if ((opts = ip_srcroute()) == 0 &&
672 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
673 opts->m_len = sizeof(struct in_addr);
674 mtod(opts, struct in_addr *)->s_addr = 0;
679 printf("icmp_reflect optlen %d rt %d => ",
680 optlen, opts->m_len);
682 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
683 opt = cp[IPOPT_OPTVAL];
684 if (opt == IPOPT_EOL)
686 if (opt == IPOPT_NOP)
689 if (cnt < IPOPT_OLEN + sizeof(*cp))
691 len = cp[IPOPT_OLEN];
692 if (len < IPOPT_OLEN + sizeof(*cp) ||
697 * Should check for overflow, but it "can't happen"
699 if (opt == IPOPT_RR || opt == IPOPT_TS ||
700 opt == IPOPT_SECURITY) {
702 mtod(opts, caddr_t) + opts->m_len, len);
706 /* Terminate & pad, if necessary */
707 cnt = opts->m_len % 4;
709 for (; cnt < 4; cnt++) {
710 *(mtod(opts, caddr_t) + opts->m_len) =
717 printf("%d\n", opts->m_len);
721 * Now strip out original options by copying rest of first
722 * mbuf's data back, and adjust the IP length.
724 ip->ip_len -= optlen;
725 ip->ip_vhl = IP_VHL_BORING;
727 if (m->m_flags & M_PKTHDR)
728 m->m_pkthdr.len -= optlen;
729 optlen += sizeof(struct ip);
730 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
731 (unsigned)(m->m_len - sizeof(struct ip)));
733 m->m_flags &= ~(M_BCAST|M_MCAST);
734 icmp_send(m, opts, ro);
743 * Send an icmp packet back to the ip level,
744 * after supplying a checksum.
747 icmp_send(m, opts, rt)
752 struct ip *ip = mtod(m, struct ip *);
756 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
759 icp = mtod(m, struct icmp *);
761 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
764 m->m_pkthdr.rcvif = (struct ifnet *)0;
767 char buf[4 * sizeof "123"];
768 strcpy(buf, inet_ntoa(ip->ip_dst));
769 printf("icmp_send dst %s src %s\n",
770 buf, inet_ntoa(ip->ip_src));
773 (void) ip_output(m, opts, rt, 0, NULL, NULL);
783 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
789 * Return the next larger or smaller MTU plateau (table from RFC 1191)
790 * given current value MTU. If DIR is less than zero, a larger plateau
791 * is returned; otherwise, a smaller value is returned.
794 ip_next_mtu(mtu, dir)
798 static int mtutab[] = {
799 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
804 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
805 if (mtu >= mtutab[i])
813 return mtutab[i - 1];
816 if (mtutab[i] == 0) {
818 } else if(mtu > mtutab[i]) {
821 return mtutab[i + 1];
830 * badport_bandlim() - check for ICMP bandwidth limit
832 * Return 0 if it is ok to send an ICMP error response, -1 if we have
833 * hit our bandwidth limit and it is not ok.
835 * If icmplim is <= 0, the feature is disabled and 0 is returned.
837 * For now we separate the TCP and UDP subsystems w/ different 'which'
838 * values. We may eventually remove this separation (and simplify the
841 * Note that the printing of the error message is delayed so we can
842 * properly print the icmp error rate that the system was trying to do
843 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
844 * the 'final' error, but it doesn't make sense to solve the printing
845 * delay with more complex code.
849 badport_bandlim(int which)
851 static int lticks[BANDLIM_MAX + 1];
852 static int lpackets[BANDLIM_MAX + 1];
854 const char *bandlimittype[] = {
855 "Limiting icmp unreach response",
856 "Limiting icmp ping response",
857 "Limiting icmp tstamp response",
858 "Limiting closed port RST response",
859 "Limiting open port RST response"
863 * Return ok status if feature disabled or argument out of
867 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0)
869 dticks = ticks - lticks[which];
872 * reset stats when cumulative dt exceeds one second.
875 if ((unsigned int)dticks > hz) {
876 if (lpackets[which] > icmplim && icmplim_output) {
877 printf("%s from %d to %d packets per second\n",
878 bandlimittype[which],
883 lticks[which] = ticks;
891 if (++lpackets[which] > icmplim) {