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.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
37 #include <sys/param.h>
38 #include <sys/systm.h>
40 #include <sys/protosw.h>
41 #include <sys/socket.h>
43 #include <sys/kernel.h>
45 #include <sys/rmlock.h>
46 #include <sys/sysctl.h>
47 #include <sys/syslog.h>
50 #include <net/if_var.h>
51 #include <net/if_types.h>
52 #include <net/route.h>
55 #include <netinet/in.h>
56 #include <netinet/in_fib.h>
57 #include <netinet/in_pcb.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/ip_options.h>
64 #include <netinet/tcp.h>
65 #include <netinet/tcp_var.h>
66 #include <netinet/tcpip.h>
67 #include <netinet/icmp_var.h>
71 #include <machine/in_cksum.h>
73 #include <security/mac/mac_framework.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.
81 static VNET_DEFINE(int, icmplim) = 200;
82 #define V_icmplim VNET(icmplim)
83 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW,
84 &VNET_NAME(icmplim), 0,
85 "Maximum number of ICMP responses per second");
87 static VNET_DEFINE(int, icmplim_output) = 1;
88 #define V_icmplim_output VNET(icmplim_output)
89 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW,
90 &VNET_NAME(icmplim_output), 0,
91 "Enable logging of ICMP response rate limiting");
94 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat);
95 VNET_PCPUSTAT_SYSINIT(icmpstat);
96 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat,
97 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)");
100 VNET_PCPUSTAT_SYSUNINIT(icmpstat);
103 static VNET_DEFINE(int, icmpmaskrepl) = 0;
104 #define V_icmpmaskrepl VNET(icmpmaskrepl)
105 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW,
106 &VNET_NAME(icmpmaskrepl), 0,
107 "Reply to ICMP Address Mask Request packets.");
109 static VNET_DEFINE(u_int, icmpmaskfake) = 0;
110 #define V_icmpmaskfake VNET(icmpmaskfake)
111 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW,
112 &VNET_NAME(icmpmaskfake), 0,
113 "Fake reply to ICMP Address Mask Request packets.");
115 VNET_DEFINE(int, drop_redirect) = 0;
116 #define V_drop_redirect VNET(drop_redirect)
117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW,
118 &VNET_NAME(drop_redirect), 0, "Ignore ICMP redirects");
120 static VNET_DEFINE(int, log_redirect) = 0;
121 #define V_log_redirect VNET(log_redirect)
122 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW,
123 &VNET_NAME(log_redirect), 0,
124 "Log ICMP redirects to the console");
126 static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
127 #define V_reply_src VNET(reply_src)
128 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW,
129 &VNET_NAME(reply_src), IFNAMSIZ,
130 "icmp reply source for non-local packets.");
132 static VNET_DEFINE(int, icmp_rfi) = 0;
133 #define V_icmp_rfi VNET(icmp_rfi)
134 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW,
135 &VNET_NAME(icmp_rfi), 0,
136 "ICMP reply from incoming interface for non-local packets");
138 static VNET_DEFINE(int, icmp_quotelen) = 8;
139 #define V_icmp_quotelen VNET(icmp_quotelen)
140 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW,
141 &VNET_NAME(icmp_quotelen), 0,
142 "Number of bytes from original packet to quote in ICMP reply");
145 * ICMP broadcast echo sysctl
147 static VNET_DEFINE(int, icmpbmcastecho) = 0;
148 #define V_icmpbmcastecho VNET(icmpbmcastecho)
149 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW,
150 &VNET_NAME(icmpbmcastecho), 0,
153 static VNET_DEFINE(int, icmptstamprepl) = 1;
154 #define V_icmptstamprepl VNET(icmptstamprepl)
155 SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW,
156 &VNET_NAME(icmptstamprepl), 0, "Respond to ICMP Timestamp packets");
162 static void icmp_reflect(struct mbuf *);
163 static void icmp_send(struct mbuf *, struct mbuf *);
165 extern struct protosw inetsw[];
168 * Kernel module interface for updating icmpstat. The argument is an index
169 * into icmpstat treated as an array of u_long. While this encodes the
170 * general layout of icmpstat into the caller, it doesn't encode its
171 * location, so that future changes to add, for example, per-CPU stats
172 * support won't cause binary compatibility problems for kernel modules.
175 kmod_icmpstat_inc(int statnum)
178 counter_u64_add(VNET(icmpstat)[statnum], 1);
182 * Generate an error packet of type error
183 * in response to bad packet ip.
186 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
188 register struct ip *oip = mtod(n, struct ip *), *nip;
189 register unsigned oiphlen = oip->ip_hl << 2;
190 register struct icmp *icp;
191 register struct mbuf *m;
192 unsigned icmplen, icmpelen, nlen;
194 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
197 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
199 if (type != ICMP_REDIRECT)
200 ICMPSTAT_INC(icps_error);
203 * if the original packet was encrypted.
204 * if not the first fragment of message.
205 * in response to a multicast or broadcast packet.
206 * if the old packet protocol was an ICMP error message.
208 if (n->m_flags & M_DECRYPTED)
210 if (oip->ip_off & htons(~(IP_MF|IP_DF)))
212 if (n->m_flags & (M_BCAST|M_MCAST))
214 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
215 n->m_len >= oiphlen + ICMP_MINLEN &&
216 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
217 ICMPSTAT_INC(icps_oldicmp);
220 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
221 if (oiphlen + 8 > n->m_len)
224 * Calculate length to quote from original packet and
225 * prevent the ICMP mbuf from overflowing.
226 * Unfortunatly this is non-trivial since ip_forward()
227 * sends us truncated packets.
229 nlen = m_length(n, NULL);
230 if (oip->ip_p == IPPROTO_TCP) {
234 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
237 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
238 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
240 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
241 tcphlen = th->th_off << 2;
242 if (tcphlen < sizeof(struct tcphdr))
244 if (ntohs(oip->ip_len) < oiphlen + tcphlen)
246 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
248 if (n->m_len < oiphlen + tcphlen &&
249 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
251 icmpelen = max(tcphlen, min(V_icmp_quotelen,
252 ntohs(oip->ip_len) - oiphlen));
254 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
256 icmplen = min(oiphlen + icmpelen, nlen);
257 if (icmplen < sizeof(struct ip))
260 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
261 m = m_gethdr(M_NOWAIT, MT_DATA);
263 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
267 mac_netinet_icmp_reply(n, m);
269 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
270 m_align(m, ICMP_MINLEN + icmplen);
271 m->m_len = ICMP_MINLEN + icmplen;
273 /* XXX MRT make the outgoing packet use the same FIB
274 * that was associated with the incoming packet
276 M_SETFIB(m, M_GETFIB(n));
277 icp = mtod(m, struct icmp *);
278 ICMPSTAT_INC(icps_outhist[type]);
279 icp->icmp_type = type;
280 if (type == ICMP_REDIRECT)
281 icp->icmp_gwaddr.s_addr = dest;
285 * The following assignments assume an overlay with the
286 * just zeroed icmp_void field.
288 if (type == ICMP_PARAMPROB) {
289 icp->icmp_pptr = code;
291 } else if (type == ICMP_UNREACH &&
292 code == ICMP_UNREACH_NEEDFRAG && mtu) {
293 icp->icmp_nextmtu = htons(mtu);
296 icp->icmp_code = code;
299 * Copy the quotation into ICMP message and
300 * convert quoted IP header back to network representation.
302 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
306 * Set up ICMP message mbuf and copy old IP header (without options
307 * in front of ICMP message.
308 * If the original mbuf was meant to bypass the firewall, the error
309 * reply should bypass as well.
311 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
312 m->m_data -= sizeof(struct ip);
313 m->m_len += sizeof(struct ip);
314 m->m_pkthdr.len = m->m_len;
315 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
316 nip = mtod(m, struct ip *);
317 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
318 nip->ip_len = htons(m->m_len);
319 nip->ip_v = IPVERSION;
321 nip->ip_p = IPPROTO_ICMP;
331 * Process a received ICMP message.
334 icmp_input(struct mbuf **mp, int *offp, int proto)
337 struct in_ifaddr *ia;
338 struct mbuf *m = *mp;
339 struct ip *ip = mtod(m, struct ip *);
340 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
342 int icmplen = ntohs(ip->ip_len) - *offp;
344 void (*ctlfunc)(int, struct sockaddr *, void *);
350 * Locate icmp structure in mbuf, and check
351 * that not corrupted and of at least minimum length.
355 char buf[4 * sizeof "123"];
356 strcpy(buf, inet_ntoa(ip->ip_src));
357 printf("icmp_input from %s to %s, len %d\n",
358 buf, inet_ntoa(ip->ip_dst), icmplen);
361 if (icmplen < ICMP_MINLEN) {
362 ICMPSTAT_INC(icps_tooshort);
365 i = hlen + min(icmplen, ICMP_ADVLENMIN);
366 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
367 ICMPSTAT_INC(icps_tooshort);
368 return (IPPROTO_DONE);
370 ip = mtod(m, struct ip *);
373 icp = mtod(m, struct icmp *);
374 if (in_cksum(m, icmplen)) {
375 ICMPSTAT_INC(icps_checksum);
383 printf("icmp_input, type %d code %d\n", icp->icmp_type,
388 * Message type specific processing.
390 if (icp->icmp_type > ICMP_MAXTYPE)
394 bzero(&icmpsrc, sizeof(icmpsrc));
395 icmpsrc.sin_len = sizeof(struct sockaddr_in);
396 icmpsrc.sin_family = AF_INET;
397 bzero(&icmpdst, sizeof(icmpdst));
398 icmpdst.sin_len = sizeof(struct sockaddr_in);
399 icmpdst.sin_family = AF_INET;
400 bzero(&icmpgw, sizeof(icmpgw));
401 icmpgw.sin_len = sizeof(struct sockaddr_in);
402 icmpgw.sin_family = AF_INET;
404 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
405 code = icp->icmp_code;
406 switch (icp->icmp_type) {
410 case ICMP_UNREACH_NET:
411 case ICMP_UNREACH_HOST:
412 case ICMP_UNREACH_SRCFAIL:
413 case ICMP_UNREACH_NET_UNKNOWN:
414 case ICMP_UNREACH_HOST_UNKNOWN:
415 case ICMP_UNREACH_ISOLATED:
416 case ICMP_UNREACH_TOSNET:
417 case ICMP_UNREACH_TOSHOST:
418 case ICMP_UNREACH_HOST_PRECEDENCE:
419 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
420 code = PRC_UNREACH_NET;
423 case ICMP_UNREACH_NEEDFRAG:
428 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
429 * Treat subcodes 2,3 as immediate RST
431 case ICMP_UNREACH_PROTOCOL:
432 case ICMP_UNREACH_PORT:
433 code = PRC_UNREACH_PORT;
436 case ICMP_UNREACH_NET_PROHIB:
437 case ICMP_UNREACH_HOST_PROHIB:
438 case ICMP_UNREACH_FILTER_PROHIB:
439 code = PRC_UNREACH_ADMIN_PROHIB;
450 code += PRC_TIMXCEED_INTRANS;
456 code = PRC_PARAMPROB;
459 * Problem with datagram; advise higher level routines.
461 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
462 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
463 ICMPSTAT_INC(icps_badlen);
466 /* Discard ICMP's in response to multicast packets */
467 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
471 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
473 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
475 * XXX if the packet contains [IPv4 AH TCP], we can't make a
476 * notification to TCP layer.
478 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp));
480 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
481 /* This should actually not happen */
482 ICMPSTAT_INC(icps_tooshort);
483 return (IPPROTO_DONE);
485 ip = mtod(m, struct ip *);
486 icp = (struct icmp *)(ip + 1);
488 * The upper layer handler can rely on:
489 * - The outer IP header has no options.
490 * - The outer IP header, the ICMP header, the inner IP header,
491 * and the first n bytes of the inner payload are contiguous.
492 * n is at least 8, but might be larger based on
493 * ICMP_ADVLENPREF. See its definition in ip_icmp.h.
495 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
497 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
498 (void *)&icp->icmp_ip);
502 ICMPSTAT_INC(icps_badcode);
506 if (!V_icmpbmcastecho
507 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
508 ICMPSTAT_INC(icps_bmcastecho);
511 icp->icmp_type = ICMP_ECHOREPLY;
512 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
518 if (V_icmptstamprepl == 0)
520 if (!V_icmpbmcastecho
521 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
522 ICMPSTAT_INC(icps_bmcasttstamp);
525 if (icmplen < ICMP_TSLEN) {
526 ICMPSTAT_INC(icps_badlen);
529 icp->icmp_type = ICMP_TSTAMPREPLY;
530 icp->icmp_rtime = iptime();
531 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
532 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
538 if (V_icmpmaskrepl == 0)
541 * We are not able to respond with all ones broadcast
542 * unless we receive it over a point-to-point interface.
544 if (icmplen < ICMP_MASKLEN)
546 switch (ip->ip_dst.s_addr) {
548 case INADDR_BROADCAST:
550 icmpdst.sin_addr = ip->ip_src;
554 icmpdst.sin_addr = ip->ip_dst;
556 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
557 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
560 if (ia->ia_ifp == NULL) {
561 ifa_free(&ia->ia_ifa);
564 icp->icmp_type = ICMP_MASKREPLY;
565 if (V_icmpmaskfake == 0)
566 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
568 icp->icmp_mask = V_icmpmaskfake;
569 if (ip->ip_src.s_addr == 0) {
570 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
571 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
572 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
573 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
575 ifa_free(&ia->ia_ifa);
577 ICMPSTAT_INC(icps_reflect);
578 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
580 return (IPPROTO_DONE);
583 if (V_log_redirect) {
586 src = ntohl(ip->ip_src.s_addr);
587 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
588 gw = ntohl(icp->icmp_gwaddr.s_addr);
589 printf("icmp redirect from %d.%d.%d.%d: "
590 "%d.%d.%d.%d => %d.%d.%d.%d\n",
591 (int)(src >> 24), (int)((src >> 16) & 0xff),
592 (int)((src >> 8) & 0xff), (int)(src & 0xff),
593 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
594 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
595 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
596 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
599 * RFC1812 says we must ignore ICMP redirects if we
600 * are acting as router.
602 if (V_drop_redirect || V_ipforwarding)
606 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
607 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
608 ICMPSTAT_INC(icps_badlen);
612 * Short circuit routing redirects to force
613 * immediate change in the kernel's routing
614 * tables. The message is also handed to anyone
615 * listening on a raw socket (e.g. the routing
616 * daemon for use in updating its tables).
618 icmpgw.sin_addr = ip->ip_src;
619 icmpdst.sin_addr = icp->icmp_gwaddr;
622 char buf[4 * sizeof "123"];
623 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
625 printf("redirect dst %s to %s\n",
626 buf, inet_ntoa(icp->icmp_gwaddr));
629 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
630 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
631 in_rtredirect((struct sockaddr *)&icmpsrc,
632 (struct sockaddr *)&icmpdst,
633 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
634 (struct sockaddr *)&icmpgw, fibnum);
636 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
640 * No kernel processing for the following;
641 * just fall through to send to raw listener.
644 case ICMP_ROUTERADVERT:
645 case ICMP_ROUTERSOLICIT:
646 case ICMP_TSTAMPREPLY:
649 case ICMP_SOURCEQUENCH:
656 rip_input(mp, offp, proto);
657 return (IPPROTO_DONE);
661 return (IPPROTO_DONE);
665 * Reflect the ip packet back to the source
668 icmp_reflect(struct mbuf *m)
670 struct rm_priotracker in_ifa_tracker;
671 struct ip *ip = mtod(m, struct ip *);
674 struct in_ifaddr *ia;
676 struct nhop4_extended nh_ext;
677 struct mbuf *opts = NULL;
678 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
680 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
681 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
682 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
683 m_freem(m); /* Bad return address */
684 ICMPSTAT_INC(icps_badaddr);
685 goto done; /* Ip_output() will check for broadcast */
689 ip->ip_dst = ip->ip_src;
692 * Source selection for ICMP replies:
694 * If the incoming packet was addressed directly to one of our
695 * own addresses, use dst as the src for the reply.
697 IN_IFADDR_RLOCK(&in_ifa_tracker);
698 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
699 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
700 t = IA_SIN(ia)->sin_addr;
701 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
705 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
708 * If the incoming packet was addressed to one of our broadcast
709 * addresses, use the first non-broadcast address which corresponds
710 * to the incoming interface.
712 ifp = m->m_pkthdr.rcvif;
713 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
715 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
716 if (ifa->ifa_addr->sa_family != AF_INET)
719 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
721 t = IA_SIN(ia)->sin_addr;
722 IF_ADDR_RUNLOCK(ifp);
726 IF_ADDR_RUNLOCK(ifp);
729 * If the packet was transiting through us, use the address of
730 * the interface the packet came through in. If that interface
731 * doesn't have a suitable IP address, the normal selection
734 if (V_icmp_rfi && ifp != NULL) {
736 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
737 if (ifa->ifa_addr->sa_family != AF_INET)
740 t = IA_SIN(ia)->sin_addr;
741 IF_ADDR_RUNLOCK(ifp);
744 IF_ADDR_RUNLOCK(ifp);
747 * If the incoming packet was not addressed directly to us, use
748 * designated interface for icmp replies specified by sysctl
749 * net.inet.icmp.reply_src (default not set). Otherwise continue
750 * with normal source selection.
752 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
754 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
755 if (ifa->ifa_addr->sa_family != AF_INET)
758 t = IA_SIN(ia)->sin_addr;
759 IF_ADDR_RUNLOCK(ifp);
762 IF_ADDR_RUNLOCK(ifp);
765 * If the packet was transiting through us, use the address of
766 * the interface that is the closest to the packet source.
767 * When we don't have a route back to the packet source, stop here
768 * and drop the packet.
770 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) {
772 ICMPSTAT_INC(icps_noroute);
778 mac_netinet_icmp_replyinplace(m);
781 ip->ip_ttl = V_ip_defttl;
789 * Retrieve any source routing from the incoming packet;
790 * add on any record-route or timestamp options.
792 cp = (u_char *) (ip + 1);
793 if ((opts = ip_srcroute(m)) == NULL &&
794 (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
795 opts->m_len = sizeof(struct in_addr);
796 mtod(opts, struct in_addr *)->s_addr = 0;
801 printf("icmp_reflect optlen %d rt %d => ",
802 optlen, opts->m_len);
804 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
805 opt = cp[IPOPT_OPTVAL];
806 if (opt == IPOPT_EOL)
808 if (opt == IPOPT_NOP)
811 if (cnt < IPOPT_OLEN + sizeof(*cp))
813 len = cp[IPOPT_OLEN];
814 if (len < IPOPT_OLEN + sizeof(*cp) ||
819 * Should check for overflow, but it "can't happen"
821 if (opt == IPOPT_RR || opt == IPOPT_TS ||
822 opt == IPOPT_SECURITY) {
824 mtod(opts, caddr_t) + opts->m_len, len);
828 /* Terminate & pad, if necessary */
829 cnt = opts->m_len % 4;
831 for (; cnt < 4; cnt++) {
832 *(mtod(opts, caddr_t) + opts->m_len) =
839 printf("%d\n", opts->m_len);
844 m_tag_delete_nonpersistent(m);
845 m->m_flags &= ~(M_BCAST|M_MCAST);
853 * Send an icmp packet back to the ip level,
854 * after supplying a checksum.
857 icmp_send(struct mbuf *m, struct mbuf *opts)
859 register struct ip *ip = mtod(m, struct ip *);
861 register struct icmp *icp;
863 hlen = ip->ip_hl << 2;
866 icp = mtod(m, struct icmp *);
868 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
871 m->m_pkthdr.rcvif = (struct ifnet *)0;
874 char buf[4 * sizeof "123"];
875 strcpy(buf, inet_ntoa(ip->ip_dst));
876 printf("icmp_send dst %s src %s\n",
877 buf, inet_ntoa(ip->ip_src));
880 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
884 * Return milliseconds since 00:00 UTC in network format.
893 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
898 * Return the next larger or smaller MTU plateau (table from RFC 1191)
899 * given current value MTU. If DIR is less than zero, a larger plateau
900 * is returned; otherwise, a smaller value is returned.
903 ip_next_mtu(int mtu, int dir)
905 static int mtutab[] = {
906 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
911 size = (sizeof mtutab) / (sizeof mtutab[0]);
913 for (i = 0; i < size; i++)
917 for (i = size - 1; i >= 0; i--)
920 if (mtu == mtutab[0])
929 * badport_bandlim() - check for ICMP bandwidth limit
931 * Return 0 if it is ok to send an ICMP error response, -1 if we have
932 * hit our bandwidth limit and it is not ok.
934 * If icmplim is <= 0, the feature is disabled and 0 is returned.
936 * For now we separate the TCP and UDP subsystems w/ different 'which'
937 * values. We may eventually remove this separation (and simplify the
940 * Note that the printing of the error message is delayed so we can
941 * properly print the icmp error rate that the system was trying to do
942 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
943 * the 'final' error, but it doesn't make sense to solve the printing
944 * delay with more complex code.
948 badport_bandlim(int which)
951 #define N(a) (sizeof (a) / sizeof (a[0]))
954 struct timeval lasttime;
956 } rates[BANDLIM_MAX+1] = {
957 { "icmp unreach response" },
958 { "icmp ping response" },
959 { "icmp tstamp response" },
960 { "closed port RST response" },
961 { "open port RST response" },
962 { "icmp6 unreach response" },
963 { "sctp ootb response" }
967 * Return ok status if feature disabled or argument out of range.
969 if (V_icmplim > 0 && (u_int) which < N(rates)) {
970 struct rate *r = &rates[which];
971 int opps = r->curpps;
973 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
974 return -1; /* discard packet */
976 * If we've dropped below the threshold after having
977 * rate-limited traffic print the message. This preserves
978 * the previous behaviour at the expense of added complexity.
980 if (V_icmplim_output && opps > V_icmplim)
981 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
982 r->type, opps, V_icmplim);
984 return 0; /* okay to send packet */