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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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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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 1.13 2004/10/15 22:59:10 hsu 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>
50 #include <machine/stdarg.h>
53 #include <net/if_types.h>
54 #include <net/route.h>
57 #include <netinet/in.h>
58 #include <netinet/in_systm.h>
59 #include <netinet/in_var.h>
60 #include <netinet/ip.h>
61 #include <netinet/ip_icmp.h>
62 #include <netinet/ip_var.h>
63 #include <netinet/icmp_var.h>
66 #include <netinet6/ipsec.h>
67 #include <netproto/key/key.h>
71 #include <netproto/ipsec/ipsec.h>
72 #include <netproto/ipsec/key.h>
77 * ICMP routines: error generation, receive packet processing, and
78 * routines to turnaround packets back to the originator, and
79 * host table maintenance routines.
82 struct icmpstat icmpstat;
83 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
84 &icmpstat, icmpstat, "");
86 static int icmpmaskrepl = 0;
87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
88 &icmpmaskrepl, 0, "");
90 static int drop_redirect = 0;
91 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
92 &drop_redirect, 0, "");
94 static int log_redirect = 0;
95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
96 &log_redirect, 0, "");
101 * ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl
102 * variable content is -1 and read-only.
105 static int icmplim = 200;
106 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
110 static int icmplim = -1;
111 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD,
116 static int icmplim_output = 1;
117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
118 &icmplim_output, 0, "");
121 * ICMP broadcast echo sysctl
124 static int icmpbmcastecho = 0;
125 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
126 &icmpbmcastecho, 0, "");
133 static void icmp_reflect (struct mbuf *);
134 static void icmp_send (struct mbuf *, struct mbuf *, struct route *);
135 static int ip_next_mtu (int, int);
137 extern struct protosw inetsw[];
140 * Generate an error packet of type error
141 * in response to bad packet ip.
144 icmp_error(n, type, code, dest, destifp)
148 struct ifnet *destifp;
150 struct ip *oip = mtod(n, struct ip *), *nip;
151 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
158 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
160 if (type != ICMP_REDIRECT)
161 icmpstat.icps_error++;
163 * Don't send error if the original packet was encrypted.
164 * Don't send error if not the first fragment of message.
165 * Don't error if the old packet protocol was ICMP
166 * error message, only known informational types.
168 if (n->m_flags & M_DECRYPTED)
170 if (oip->ip_off &~ (IP_MF|IP_DF))
172 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
173 n->m_len >= oiplen + ICMP_MINLEN &&
174 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
175 icmpstat.icps_oldicmp++;
178 /* Don't send error in response to a multicast or broadcast packet */
179 if (n->m_flags & (M_BCAST|M_MCAST))
182 * First, formulate icmp message
184 m = m_gethdr(MB_DONTWAIT, MT_HEADER);
187 icmplen = min(oiplen + 8, oip->ip_len);
188 if (icmplen < sizeof(struct ip))
189 panic("icmp_error: bad length");
190 m->m_len = icmplen + ICMP_MINLEN;
191 MH_ALIGN(m, m->m_len);
192 icp = mtod(m, struct icmp *);
193 if ((u_int)type > ICMP_MAXTYPE)
195 icmpstat.icps_outhist[type]++;
196 icp->icmp_type = type;
197 if (type == ICMP_REDIRECT)
198 icp->icmp_gwaddr.s_addr = dest;
202 * The following assignments assume an overlay with the
203 * zeroed icmp_void field.
205 if (type == ICMP_PARAMPROB) {
206 icp->icmp_pptr = code;
208 } else if (type == ICMP_UNREACH &&
209 code == ICMP_UNREACH_NEEDFRAG && destifp) {
210 icp->icmp_nextmtu = htons(destifp->if_mtu);
214 icp->icmp_code = code;
215 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
219 * Convert fields to network representation.
221 nip->ip_len = htons(nip->ip_len);
222 nip->ip_off = htons(nip->ip_off);
225 * Now, copy old ip header (without options)
226 * in front of icmp message.
228 if (m->m_data - sizeof(struct ip) < m->m_pktdat)
230 m->m_data -= sizeof(struct ip);
231 m->m_len += sizeof(struct ip);
232 m->m_pkthdr.len = m->m_len;
233 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
234 nip = mtod(m, struct ip *);
235 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
236 nip->ip_len = m->m_len;
237 nip->ip_vhl = IP_VHL_BORING;
238 nip->ip_p = IPPROTO_ICMP;
240 m->m_pkthdr.pf_flags |= n->m_pkthdr.pf_flags & PF_MBUF_GENERATED;
247 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
248 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
249 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
252 * Process a received ICMP message.
255 icmp_input(struct mbuf *m, ...)
259 struct ip *ip = mtod(m, struct ip *);
260 int icmplen = ip->ip_len;
262 struct in_ifaddr *ia;
263 void (*ctlfunc) (int, struct sockaddr *, void *);
264 int code, off, proto;
268 off = __va_arg(ap, int);
269 proto = __va_arg(ap, int);
275 * Locate icmp structure in mbuf, and check
276 * that not corrupted and of at least minimum length.
280 char buf[4 * sizeof "123"];
281 strcpy(buf, inet_ntoa(ip->ip_src));
282 printf("icmp_input from %s to %s, len %d\n",
283 buf, inet_ntoa(ip->ip_dst), icmplen);
286 if (icmplen < ICMP_MINLEN) {
287 icmpstat.icps_tooshort++;
290 i = hlen + min(icmplen, ICMP_ADVLENMIN);
291 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
292 icmpstat.icps_tooshort++;
295 ip = mtod(m, struct ip *);
298 icp = mtod(m, struct icmp *);
299 if (in_cksum(m, icmplen)) {
300 icmpstat.icps_checksum++;
306 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
308 * Deliver very specific ICMP type only.
310 switch (icp->icmp_type) {
321 printf("icmp_input, type %d code %d\n", icp->icmp_type,
326 * Message type specific processing.
328 if (icp->icmp_type > ICMP_MAXTYPE)
330 icmpstat.icps_inhist[icp->icmp_type]++;
331 code = icp->icmp_code;
332 switch (icp->icmp_type) {
336 case ICMP_UNREACH_NET:
337 case ICMP_UNREACH_HOST:
338 case ICMP_UNREACH_SRCFAIL:
339 case ICMP_UNREACH_NET_UNKNOWN:
340 case ICMP_UNREACH_HOST_UNKNOWN:
341 case ICMP_UNREACH_ISOLATED:
342 case ICMP_UNREACH_TOSNET:
343 case ICMP_UNREACH_TOSHOST:
344 case ICMP_UNREACH_HOST_PRECEDENCE:
345 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
346 code = PRC_UNREACH_NET;
349 case ICMP_UNREACH_NEEDFRAG:
354 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
355 * Treat subcodes 2,3 as immediate RST
357 case ICMP_UNREACH_PROTOCOL:
358 case ICMP_UNREACH_PORT:
359 code = PRC_UNREACH_PORT;
362 case ICMP_UNREACH_NET_PROHIB:
363 case ICMP_UNREACH_HOST_PROHIB:
364 case ICMP_UNREACH_FILTER_PROHIB:
365 code = PRC_UNREACH_ADMIN_PROHIB;
376 code += PRC_TIMXCEED_INTRANS;
382 code = PRC_PARAMPROB;
385 case ICMP_SOURCEQUENCH:
391 * Problem with datagram; advise higher level routines.
393 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
394 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
395 icmpstat.icps_badlen++;
398 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
399 /* Discard ICMP's in response to multicast packets */
400 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
404 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
406 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
410 * If we got a needfrag and there is a host route to the
411 * original destination, and the MTU is not locked, then
412 * set the MTU in the route to the suggested new value
413 * (if given) and then notify as usual. The ULPs will
414 * notice that the MTU has changed and adapt accordingly.
415 * If no new MTU was suggested, then we guess a new one
416 * less than the current value. If the new MTU is
417 * unreasonably small (arbitrarily set at 296), then
418 * we reset the MTU to the interface value and enable the
419 * lock bit, indicating that we are no longer doing MTU
422 if (code == PRC_MSGSIZE) {
426 rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
427 RTF_CLONING | RTF_PRCLONING);
428 if (rt && (rt->rt_flags & RTF_HOST)
429 && !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
430 mtu = ntohs(icp->icmp_nextmtu);
432 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
435 printf("MTU for %s reduced to %d\n",
436 inet_ntoa(icmpsrc.sin_addr), mtu);
439 /* rt->rt_rmx.rmx_mtu =
440 rt->rt_ifp->if_mtu; */
441 rt->rt_rmx.rmx_locks |= RTV_MTU;
442 } else if (rt->rt_rmx.rmx_mtu > mtu) {
443 rt->rt_rmx.rmx_mtu = mtu;
452 * XXX if the packet contains [IPv4 AH TCP], we can't make a
453 * notification to TCP layer.
455 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
457 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
458 (void *)&icp->icmp_ip);
462 icmpstat.icps_badcode++;
467 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
468 icmpstat.icps_bmcastecho++;
471 icp->icmp_type = ICMP_ECHOREPLY;
473 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
481 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
482 icmpstat.icps_bmcasttstamp++;
485 if (icmplen < ICMP_TSLEN) {
486 icmpstat.icps_badlen++;
489 icp->icmp_type = ICMP_TSTAMPREPLY;
490 icp->icmp_rtime = iptime();
491 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
493 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
500 if (icmpmaskrepl == 0)
503 * We are not able to respond with all ones broadcast
504 * unless we receive it over a point-to-point interface.
506 if (icmplen < ICMP_MASKLEN)
508 switch (ip->ip_dst.s_addr) {
510 case INADDR_BROADCAST:
512 icmpdst.sin_addr = ip->ip_src;
516 icmpdst.sin_addr = ip->ip_dst;
518 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
519 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
524 icp->icmp_type = ICMP_MASKREPLY;
525 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
526 if (ip->ip_src.s_addr == 0) {
527 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
528 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
529 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
530 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
533 ip->ip_len += hlen; /* since ip_input deducts this */
534 icmpstat.icps_reflect++;
535 icmpstat.icps_outhist[icp->icmp_type]++;
543 src = ntohl(ip->ip_src.s_addr);
544 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
545 gw = ntohl(icp->icmp_gwaddr.s_addr);
546 printf("icmp redirect from %d.%d.%d.%d: "
547 "%d.%d.%d.%d => %d.%d.%d.%d\n",
548 (int)(src >> 24), (int)((src >> 16) & 0xff),
549 (int)((src >> 8) & 0xff), (int)(src & 0xff),
550 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
551 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
552 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
553 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
559 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
560 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
561 icmpstat.icps_badlen++;
565 * Short circuit routing redirects to force
566 * immediate change in the kernel's routing
567 * tables. The message is also handed to anyone
568 * listening on a raw socket (e.g. the routing
569 * daemon for use in updating its tables).
571 icmpgw.sin_addr = ip->ip_src;
572 icmpdst.sin_addr = icp->icmp_gwaddr;
575 char buf[4 * sizeof "123"];
576 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
578 printf("redirect dst %s to %s\n",
579 buf, inet_ntoa(icp->icmp_gwaddr));
582 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
583 rtredirect((struct sockaddr *)&icmpsrc,
584 (struct sockaddr *)&icmpdst,
585 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
586 (struct sockaddr *)&icmpgw, (struct rtentry **)0);
587 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
589 key_sa_routechange((struct sockaddr *)&icmpsrc);
594 * No kernel processing for the following;
595 * just fall through to send to raw listener.
598 case ICMP_ROUTERADVERT:
599 case ICMP_ROUTERSOLICIT:
600 case ICMP_TSTAMPREPLY:
608 rip_input(m, off, proto);
616 * Reflect the ip packet back to the source
622 struct ip *ip = mtod(m, struct ip *);
624 struct in_ifaddr *ia;
626 struct mbuf *opts = 0;
627 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
628 struct route *ro = NULL, rt;
630 if (!in_canforward(ip->ip_src) &&
631 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
632 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
633 m_freem(m); /* Bad return address */
634 icmpstat.icps_badaddr++;
635 goto done; /* Ip_output() will check for broadcast */
638 ip->ip_dst = ip->ip_src;
640 bzero(ro, sizeof(*ro));
642 * If the incoming packet was addressed directly to us,
643 * use dst as the src for the reply. Otherwise (broadcast
644 * or anonymous), use the address which corresponds
645 * to the incoming interface.
647 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
648 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
650 if (m->m_pkthdr.rcvif != NULL &&
651 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
652 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
653 if (ifa->ifa_addr->sa_family != AF_INET)
656 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
661 ia = ip_rtaddr(ip->ip_dst, ro);
662 /* We need a route to do anything useful. */
665 icmpstat.icps_noroute++;
669 t = IA_SIN(ia)->sin_addr;
671 ip->ip_ttl = ip_defttl;
679 * Retrieve any source routing from the incoming packet;
680 * add on any record-route or timestamp options.
682 cp = (u_char *) (ip + 1);
683 if ((opts = ip_srcroute()) == 0 &&
684 (opts = m_gethdr(MB_DONTWAIT, MT_HEADER))) {
685 opts->m_len = sizeof(struct in_addr);
686 mtod(opts, struct in_addr *)->s_addr = 0;
691 printf("icmp_reflect optlen %d rt %d => ",
692 optlen, opts->m_len);
694 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
695 opt = cp[IPOPT_OPTVAL];
696 if (opt == IPOPT_EOL)
698 if (opt == IPOPT_NOP)
701 if (cnt < IPOPT_OLEN + sizeof(*cp))
703 len = cp[IPOPT_OLEN];
704 if (len < IPOPT_OLEN + sizeof(*cp) ||
709 * Should check for overflow, but it "can't happen"
711 if (opt == IPOPT_RR || opt == IPOPT_TS ||
712 opt == IPOPT_SECURITY) {
714 mtod(opts, caddr_t) + opts->m_len, len);
718 /* Terminate & pad, if necessary */
719 cnt = opts->m_len % 4;
721 for (; cnt < 4; cnt++) {
722 *(mtod(opts, caddr_t) + opts->m_len) =
729 printf("%d\n", opts->m_len);
733 * Now strip out original options by copying rest of first
734 * mbuf's data back, and adjust the IP length.
736 ip->ip_len -= optlen;
737 ip->ip_vhl = IP_VHL_BORING;
739 if (m->m_flags & M_PKTHDR)
740 m->m_pkthdr.len -= optlen;
741 optlen += sizeof(struct ip);
742 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
743 (unsigned)(m->m_len - sizeof(struct ip)));
745 m->m_pkthdr.pf_flags &= PF_MBUF_GENERATED;
746 m->m_flags &= ~(M_BCAST|M_MCAST);
747 icmp_send(m, opts, ro);
756 * Send an icmp packet back to the ip level,
757 * after supplying a checksum.
760 icmp_send(m, opts, rt)
765 struct ip *ip = mtod(m, struct ip *);
769 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
772 icp = mtod(m, struct icmp *);
774 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
777 m->m_pkthdr.rcvif = (struct ifnet *)0;
780 char buf[4 * sizeof "123"];
781 strcpy(buf, inet_ntoa(ip->ip_dst));
782 printf("icmp_send dst %s src %s\n",
783 buf, inet_ntoa(ip->ip_src));
786 (void) ip_output(m, opts, rt, 0, NULL, NULL);
796 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
802 * Return the next larger or smaller MTU plateau (table from RFC 1191)
803 * given current value MTU. If DIR is less than zero, a larger plateau
804 * is returned; otherwise, a smaller value is returned.
807 ip_next_mtu(mtu, dir)
811 static int mtutab[] = {
812 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
817 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
818 if (mtu >= mtutab[i])
826 return mtutab[i - 1];
829 if (mtutab[i] == 0) {
831 } else if(mtu > mtutab[i]) {
834 return mtutab[i + 1];
843 * badport_bandlim() - check for ICMP bandwidth limit
845 * Return 0 if it is ok to send an ICMP error response, -1 if we have
846 * hit our bandwidth limit and it is not ok.
848 * If icmplim is <= 0, the feature is disabled and 0 is returned.
850 * For now we separate the TCP and UDP subsystems w/ different 'which'
851 * values. We may eventually remove this separation (and simplify the
854 * Note that the printing of the error message is delayed so we can
855 * properly print the icmp error rate that the system was trying to do
856 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
857 * the 'final' error, but it doesn't make sense to solve the printing
858 * delay with more complex code.
862 badport_bandlim(int which)
864 static int lticks[BANDLIM_MAX + 1];
865 static int lpackets[BANDLIM_MAX + 1];
867 const char *bandlimittype[] = {
868 "Limiting icmp unreach response",
869 "Limiting icmp ping response",
870 "Limiting icmp tstamp response",
871 "Limiting closed port RST response",
872 "Limiting open port RST response"
876 * Return ok status if feature disabled or argument out of
880 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0)
882 dticks = ticks - lticks[which];
885 * reset stats when cumulative dt exceeds one second.
888 if ((unsigned int)dticks > hz) {
889 if (lpackets[which] > icmplim && icmplim_output) {
890 printf("%s from %d to %d packets per second\n",
891 bandlimittype[which],
896 lticks[which] = ticks;
904 if (++lpackets[which] > icmplim) {