2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1982, 1986, 1988, 1993
5 * The Regents of the University of California. All rights reserved.
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8 * modification, are permitted provided that the following conditions
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31 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
39 #include <sys/param.h>
40 #include <sys/systm.h>
42 #include <sys/protosw.h>
43 #include <sys/socket.h>
45 #include <sys/kernel.h>
47 #include <sys/rmlock.h>
48 #include <sys/sysctl.h>
49 #include <sys/syslog.h>
52 #include <net/if_var.h>
53 #include <net/if_types.h>
54 #include <net/route.h>
55 #include <net/route/route_ctl.h>
56 #include <net/route/nhop.h>
59 #include <netinet/in.h>
60 #include <netinet/in_fib.h>
61 #include <netinet/in_pcb.h>
62 #include <netinet/in_systm.h>
63 #include <netinet/in_var.h>
64 #include <netinet/ip.h>
65 #include <netinet/ip_icmp.h>
66 #include <netinet/ip_var.h>
67 #include <netinet/ip_options.h>
68 #include <netinet/sctp.h>
69 #include <netinet/tcp.h>
70 #include <netinet/tcp_var.h>
71 #include <netinet/tcpip.h>
72 #include <netinet/icmp_var.h>
76 #include <machine/in_cksum.h>
78 #include <security/mac/mac_framework.h>
82 * ICMP routines: error generation, receive packet processing, and
83 * routines to turnaround packets back to the originator, and
84 * host table maintenance routines.
86 VNET_DEFINE_STATIC(int, icmplim) = 200;
87 #define V_icmplim VNET(icmplim)
88 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW,
89 &VNET_NAME(icmplim), 0,
90 "Maximum number of ICMP responses per second");
92 VNET_DEFINE_STATIC(int, icmplim_output) = 1;
93 #define V_icmplim_output VNET(icmplim_output)
94 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW,
95 &VNET_NAME(icmplim_output), 0,
96 "Enable logging of ICMP response rate limiting");
99 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat);
100 VNET_PCPUSTAT_SYSINIT(icmpstat);
101 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat,
102 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)");
105 VNET_PCPUSTAT_SYSUNINIT(icmpstat);
108 VNET_DEFINE_STATIC(int, icmpmaskrepl) = 0;
109 #define V_icmpmaskrepl VNET(icmpmaskrepl)
110 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW,
111 &VNET_NAME(icmpmaskrepl), 0,
112 "Reply to ICMP Address Mask Request packets");
114 VNET_DEFINE_STATIC(u_int, icmpmaskfake) = 0;
115 #define V_icmpmaskfake VNET(icmpmaskfake)
116 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW,
117 &VNET_NAME(icmpmaskfake), 0,
118 "Fake reply to ICMP Address Mask Request packets");
120 VNET_DEFINE(int, drop_redirect) = 0;
121 #define V_drop_redirect VNET(drop_redirect)
122 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW,
123 &VNET_NAME(drop_redirect), 0,
124 "Ignore ICMP redirects");
126 VNET_DEFINE_STATIC(int, log_redirect) = 0;
127 #define V_log_redirect VNET(log_redirect)
128 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW,
129 &VNET_NAME(log_redirect), 0,
130 "Log ICMP redirects to the console");
132 VNET_DEFINE_STATIC(int, redirtimeout) = 60 * 10; /* 10 minutes */
133 #define V_redirtimeout VNET(redirtimeout)
134 SYSCTL_INT(_net_inet_icmp, OID_AUTO, redirtimeout, CTLFLAG_VNET | CTLFLAG_RW,
135 &VNET_NAME(redirtimeout), 0,
136 "Delay in seconds before expiring redirect route");
138 VNET_DEFINE_STATIC(char, reply_src[IFNAMSIZ]);
139 #define V_reply_src VNET(reply_src)
140 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW,
141 &VNET_NAME(reply_src), IFNAMSIZ,
142 "ICMP reply source for non-local packets");
144 VNET_DEFINE_STATIC(int, icmp_rfi) = 0;
145 #define V_icmp_rfi VNET(icmp_rfi)
146 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW,
147 &VNET_NAME(icmp_rfi), 0,
148 "ICMP reply from incoming interface for non-local packets");
149 /* Router requirements RFC 1812 section 4.3.2.3 requires 576 - 28. */
150 VNET_DEFINE_STATIC(int, icmp_quotelen) = 548;
151 #define V_icmp_quotelen VNET(icmp_quotelen)
152 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW,
153 &VNET_NAME(icmp_quotelen), 0,
154 "Number of bytes from original packet to quote in ICMP reply");
156 VNET_DEFINE_STATIC(int, icmpbmcastecho) = 0;
157 #define V_icmpbmcastecho VNET(icmpbmcastecho)
158 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW,
159 &VNET_NAME(icmpbmcastecho), 0,
160 "Reply to multicast ICMP Echo Request and Timestamp packets");
162 VNET_DEFINE_STATIC(int, icmptstamprepl) = 1;
163 #define V_icmptstamprepl VNET(icmptstamprepl)
164 SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_VNET | CTLFLAG_RW,
165 &VNET_NAME(icmptstamprepl), 0,
166 "Respond to ICMP Timestamp packets");
168 VNET_DEFINE_STATIC(int, error_keeptags) = 0;
169 #define V_error_keeptags VNET(error_keeptags)
170 SYSCTL_INT(_net_inet_icmp, OID_AUTO, error_keeptags, CTLFLAG_VNET | CTLFLAG_RW,
171 &VNET_NAME(error_keeptags), 0,
172 "ICMP error response keeps copy of mbuf_tags of original packet");
178 static void icmp_reflect(struct mbuf *);
179 static void icmp_send(struct mbuf *, struct mbuf *);
180 static int icmp_verify_redirect_gateway(struct sockaddr_in *,
181 struct sockaddr_in *, struct sockaddr_in *, u_int);
183 extern struct protosw inetsw[];
186 * Kernel module interface for updating icmpstat. The argument is an index
187 * into icmpstat treated as an array of u_long. While this encodes the
188 * general layout of icmpstat into the caller, it doesn't encode its
189 * location, so that future changes to add, for example, per-CPU stats
190 * support won't cause binary compatibility problems for kernel modules.
193 kmod_icmpstat_inc(int statnum)
196 counter_u64_add(VNET(icmpstat)[statnum], 1);
200 * Generate an error packet of type error
201 * in response to bad packet ip.
204 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
206 struct ip *oip, *nip;
209 unsigned icmplen, icmpelen, nlen, oiphlen;
211 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type",
214 if (type != ICMP_REDIRECT)
215 ICMPSTAT_INC(icps_error);
218 * if the original packet was encrypted.
219 * if not the first fragment of message.
220 * in response to a multicast or broadcast packet.
221 * if the old packet protocol was an ICMP error message.
223 if (n->m_flags & M_DECRYPTED)
225 if (n->m_flags & (M_BCAST|M_MCAST))
228 /* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */
229 if (n->m_len < sizeof(struct ip) + ICMP_MINLEN)
231 oip = mtod(n, struct ip *);
232 oiphlen = oip->ip_hl << 2;
233 if (n->m_len < oiphlen + ICMP_MINLEN)
237 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
239 if (oip->ip_off & htons(~(IP_MF|IP_DF)))
241 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
242 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip +
243 oiphlen))->icmp_type)) {
244 ICMPSTAT_INC(icps_oldicmp);
248 * Calculate length to quote from original packet and
249 * prevent the ICMP mbuf from overflowing.
250 * Unfortunately this is non-trivial since ip_forward()
251 * sends us truncated packets.
253 nlen = m_length(n, NULL);
254 if (oip->ip_p == IPPROTO_TCP) {
258 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
261 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
262 (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)
264 oip = mtod(n, struct ip *);
265 th = mtodo(n, oiphlen);
266 tcphlen = th->th_off << 2;
267 if (tcphlen < sizeof(struct tcphdr))
269 if (ntohs(oip->ip_len) < oiphlen + tcphlen)
271 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
273 if (n->m_len < oiphlen + tcphlen &&
274 (n = m_pullup(n, oiphlen + tcphlen)) == NULL)
276 oip = mtod(n, struct ip *);
277 icmpelen = max(tcphlen, min(V_icmp_quotelen,
278 ntohs(oip->ip_len) - oiphlen));
279 } else if (oip->ip_p == IPPROTO_SCTP) {
281 struct sctp_chunkhdr *ch;
283 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr))
285 if (oiphlen + sizeof(struct sctphdr) > n->m_len &&
288 if (n->m_len < oiphlen + sizeof(struct sctphdr) &&
289 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL)
291 oip = mtod(n, struct ip *);
292 icmpelen = max(sizeof(struct sctphdr),
293 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
294 sh = mtodo(n, oiphlen);
295 if (ntohl(sh->v_tag) == 0 &&
296 ntohs(oip->ip_len) >= oiphlen +
297 sizeof(struct sctphdr) + 8 &&
298 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 ||
299 n->m_next != NULL)) {
300 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 &&
301 (n = m_pullup(n, oiphlen +
302 sizeof(struct sctphdr) + 8)) == NULL)
304 oip = mtod(n, struct ip *);
305 sh = mtodo(n, oiphlen);
306 ch = (struct sctp_chunkhdr *)(sh + 1);
307 if (ch->chunk_type == SCTP_INITIATION) {
308 icmpelen = max(sizeof(struct sctphdr) + 8,
309 min(V_icmp_quotelen, ntohs(oip->ip_len) -
314 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) -
317 icmplen = min(oiphlen + icmpelen, nlen);
318 if (icmplen < sizeof(struct ip))
321 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
322 m = m_gethdr(M_NOWAIT, MT_DATA);
324 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
328 mac_netinet_icmp_reply(n, m);
330 icmplen = min(icmplen, M_TRAILINGSPACE(m) -
331 sizeof(struct ip) - ICMP_MINLEN);
332 m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen);
333 m->m_data += sizeof(struct ip);
334 m->m_len = ICMP_MINLEN + icmplen;
336 /* XXX MRT make the outgoing packet use the same FIB
337 * that was associated with the incoming packet
339 M_SETFIB(m, M_GETFIB(n));
340 icp = mtod(m, struct icmp *);
341 ICMPSTAT_INC(icps_outhist[type]);
342 icp->icmp_type = type;
343 if (type == ICMP_REDIRECT)
344 icp->icmp_gwaddr.s_addr = dest;
348 * The following assignments assume an overlay with the
349 * just zeroed icmp_void field.
351 if (type == ICMP_PARAMPROB) {
352 icp->icmp_pptr = code;
354 } else if (type == ICMP_UNREACH &&
355 code == ICMP_UNREACH_NEEDFRAG && mtu) {
356 icp->icmp_nextmtu = htons(mtu);
359 icp->icmp_code = code;
362 * Copy the quotation into ICMP message and
363 * convert quoted IP header back to network representation.
365 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
369 * Set up ICMP message mbuf and copy old IP header (without options
370 * in front of ICMP message.
371 * If the original mbuf was meant to bypass the firewall, the error
372 * reply should bypass as well.
374 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
375 KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip),
376 ("insufficient space for ip header"));
377 m->m_data -= sizeof(struct ip);
378 m->m_len += sizeof(struct ip);
379 m->m_pkthdr.len = m->m_len;
380 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
381 nip = mtod(m, struct ip *);
382 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
383 nip->ip_len = htons(m->m_len);
384 nip->ip_v = IPVERSION;
386 nip->ip_p = IPPROTO_ICMP;
390 if (V_error_keeptags)
391 m_tag_copy_chain(m, n, M_NOWAIT);
400 * Process a received ICMP message.
403 icmp_input(struct mbuf **mp, int *offp, int proto)
406 struct in_ifaddr *ia;
407 struct mbuf *m = *mp;
408 struct ip *ip = mtod(m, struct ip *);
409 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
411 int icmplen = ntohs(ip->ip_len) - *offp;
413 void (*ctlfunc)(int, struct sockaddr *, void *);
421 * Locate icmp structure in mbuf, and check
422 * that not corrupted and of at least minimum length.
426 char srcbuf[INET_ADDRSTRLEN];
427 char dstbuf[INET_ADDRSTRLEN];
429 printf("icmp_input from %s to %s, len %d\n",
430 inet_ntoa_r(ip->ip_src, srcbuf),
431 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen);
434 if (icmplen < ICMP_MINLEN) {
435 ICMPSTAT_INC(icps_tooshort);
438 i = hlen + min(icmplen, ICMP_ADVLENMIN);
439 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
440 ICMPSTAT_INC(icps_tooshort);
441 return (IPPROTO_DONE);
443 ip = mtod(m, struct ip *);
446 icp = mtod(m, struct icmp *);
447 if (in_cksum(m, icmplen)) {
448 ICMPSTAT_INC(icps_checksum);
456 printf("icmp_input, type %d code %d\n", icp->icmp_type,
461 * Message type specific processing.
463 if (icp->icmp_type > ICMP_MAXTYPE)
467 bzero(&icmpsrc, sizeof(icmpsrc));
468 icmpsrc.sin_len = sizeof(struct sockaddr_in);
469 icmpsrc.sin_family = AF_INET;
470 bzero(&icmpdst, sizeof(icmpdst));
471 icmpdst.sin_len = sizeof(struct sockaddr_in);
472 icmpdst.sin_family = AF_INET;
473 bzero(&icmpgw, sizeof(icmpgw));
474 icmpgw.sin_len = sizeof(struct sockaddr_in);
475 icmpgw.sin_family = AF_INET;
477 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
478 code = icp->icmp_code;
479 switch (icp->icmp_type) {
482 case ICMP_UNREACH_NET:
483 case ICMP_UNREACH_HOST:
484 case ICMP_UNREACH_SRCFAIL:
485 case ICMP_UNREACH_NET_UNKNOWN:
486 case ICMP_UNREACH_HOST_UNKNOWN:
487 case ICMP_UNREACH_ISOLATED:
488 case ICMP_UNREACH_TOSNET:
489 case ICMP_UNREACH_TOSHOST:
490 case ICMP_UNREACH_HOST_PRECEDENCE:
491 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
492 code = PRC_UNREACH_NET;
495 case ICMP_UNREACH_NEEDFRAG:
500 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
501 * Treat subcodes 2,3 as immediate RST
503 case ICMP_UNREACH_PROTOCOL:
504 code = PRC_UNREACH_PROTOCOL;
506 case ICMP_UNREACH_PORT:
507 code = PRC_UNREACH_PORT;
510 case ICMP_UNREACH_NET_PROHIB:
511 case ICMP_UNREACH_HOST_PROHIB:
512 case ICMP_UNREACH_FILTER_PROHIB:
513 code = PRC_UNREACH_ADMIN_PROHIB;
524 code += PRC_TIMXCEED_INTRANS;
530 code = PRC_PARAMPROB;
533 * Problem with datagram; advise higher level routines.
535 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
536 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
537 ICMPSTAT_INC(icps_badlen);
540 /* Discard ICMP's in response to multicast packets */
541 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
545 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
547 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
549 * XXX if the packet contains [IPv4 AH TCP], we can't make a
550 * notification to TCP layer.
552 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp));
554 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
555 /* This should actually not happen */
556 ICMPSTAT_INC(icps_tooshort);
557 return (IPPROTO_DONE);
559 ip = mtod(m, struct ip *);
560 icp = (struct icmp *)(ip + 1);
562 * The upper layer handler can rely on:
563 * - The outer IP header has no options.
564 * - The outer IP header, the ICMP header, the inner IP header,
565 * and the first n bytes of the inner payload are contiguous.
566 * n is at least 8, but might be larger based on
567 * ICMP_ADVLENPREF. See its definition in ip_icmp.h.
569 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
571 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
572 (void *)&icp->icmp_ip);
576 ICMPSTAT_INC(icps_badcode);
580 if (!V_icmpbmcastecho
581 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
582 ICMPSTAT_INC(icps_bmcastecho);
585 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
587 icp->icmp_type = ICMP_ECHOREPLY;
591 if (V_icmptstamprepl == 0)
593 if (!V_icmpbmcastecho
594 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
595 ICMPSTAT_INC(icps_bmcasttstamp);
598 if (icmplen < ICMP_TSLEN) {
599 ICMPSTAT_INC(icps_badlen);
602 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
604 icp->icmp_type = ICMP_TSTAMPREPLY;
605 icp->icmp_rtime = iptime();
606 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
610 if (V_icmpmaskrepl == 0)
613 * We are not able to respond with all ones broadcast
614 * unless we receive it over a point-to-point interface.
616 if (icmplen < ICMP_MASKLEN)
618 switch (ip->ip_dst.s_addr) {
619 case INADDR_BROADCAST:
621 icmpdst.sin_addr = ip->ip_src;
625 icmpdst.sin_addr = ip->ip_dst;
627 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
628 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
631 if (ia->ia_ifp == NULL)
633 icp->icmp_type = ICMP_MASKREPLY;
634 if (V_icmpmaskfake == 0)
635 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
637 icp->icmp_mask = V_icmpmaskfake;
638 if (ip->ip_src.s_addr == 0) {
639 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
640 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
641 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
642 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
645 ICMPSTAT_INC(icps_reflect);
646 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
648 return (IPPROTO_DONE);
651 if (V_log_redirect) {
654 src = ntohl(ip->ip_src.s_addr);
655 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
656 gw = ntohl(icp->icmp_gwaddr.s_addr);
657 printf("icmp redirect from %d.%d.%d.%d: "
658 "%d.%d.%d.%d => %d.%d.%d.%d\n",
659 (int)(src >> 24), (int)((src >> 16) & 0xff),
660 (int)((src >> 8) & 0xff), (int)(src & 0xff),
661 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
662 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
663 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
664 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
667 * RFC1812 says we must ignore ICMP redirects if we
668 * are acting as router.
670 if (V_drop_redirect || V_ipforwarding)
674 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
675 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
676 ICMPSTAT_INC(icps_badlen);
680 * Short circuit routing redirects to force
681 * immediate change in the kernel's routing
682 * tables. The message is also handed to anyone
683 * listening on a raw socket (e.g. the routing
684 * daemon for use in updating its tables).
686 icmpgw.sin_addr = ip->ip_src;
687 icmpdst.sin_addr = icp->icmp_gwaddr;
690 char dstbuf[INET_ADDRSTRLEN];
691 char gwbuf[INET_ADDRSTRLEN];
693 printf("redirect dst %s to %s\n",
694 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf),
695 inet_ntoa_r(icp->icmp_gwaddr, gwbuf));
698 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
701 * RFC 1122 says network (code 0,2) redirects SHOULD
702 * be treated identically to the host redirects.
703 * Given that, ignore network masks.
708 * icmpsrc: route destination
709 * icmpdst: route gateway
710 * icmpgw: message source
713 if (icmp_verify_redirect_gateway(&icmpgw, &icmpsrc, &icmpdst,
715 /* TODO: increment bad redirects here */
719 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
720 rib_add_redirect(fibnum, (struct sockaddr *)&icmpsrc,
721 (struct sockaddr *)&icmpdst,
722 (struct sockaddr *)&icmpgw, m->m_pkthdr.rcvif,
723 RTF_GATEWAY, V_redirtimeout);
725 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
729 * No kernel processing for the following;
730 * just fall through to send to raw listener.
733 case ICMP_ROUTERADVERT:
734 case ICMP_ROUTERSOLICIT:
735 case ICMP_TSTAMPREPLY:
738 case ICMP_SOURCEQUENCH:
745 rip_input(mp, offp, proto);
746 return (IPPROTO_DONE);
750 return (IPPROTO_DONE);
754 * Reflect the ip packet back to the source
757 icmp_reflect(struct mbuf *m)
759 struct rm_priotracker in_ifa_tracker;
760 struct ip *ip = mtod(m, struct ip *);
763 struct in_ifaddr *ia;
765 struct nhop_object *nh;
766 struct mbuf *opts = NULL;
767 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
771 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
772 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
773 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
774 m_freem(m); /* Bad return address */
775 ICMPSTAT_INC(icps_badaddr);
776 goto done; /* Ip_output() will check for broadcast */
780 ip->ip_dst = ip->ip_src;
783 * Source selection for ICMP replies:
785 * If the incoming packet was addressed directly to one of our
786 * own addresses, use dst as the src for the reply.
788 IN_IFADDR_RLOCK(&in_ifa_tracker);
789 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
790 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
791 t = IA_SIN(ia)->sin_addr;
792 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
796 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
799 * If the incoming packet was addressed to one of our broadcast
800 * addresses, use the first non-broadcast address which corresponds
801 * to the incoming interface.
803 ifp = m->m_pkthdr.rcvif;
804 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
805 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
806 if (ifa->ifa_addr->sa_family != AF_INET)
809 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
811 t = IA_SIN(ia)->sin_addr;
817 * If the packet was transiting through us, use the address of
818 * the interface the packet came through in. If that interface
819 * doesn't have a suitable IP address, the normal selection
822 if (V_icmp_rfi && ifp != NULL) {
823 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
824 if (ifa->ifa_addr->sa_family != AF_INET)
827 t = IA_SIN(ia)->sin_addr;
832 * If the incoming packet was not addressed directly to us, use
833 * designated interface for icmp replies specified by sysctl
834 * net.inet.icmp.reply_src (default not set). Otherwise continue
835 * with normal source selection.
837 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
838 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
839 if (ifa->ifa_addr->sa_family != AF_INET)
842 t = IA_SIN(ia)->sin_addr;
847 * If the packet was transiting through us, use the address of
848 * the interface that is the closest to the packet source.
849 * When we don't have a route back to the packet source, stop here
850 * and drop the packet.
852 nh = fib4_lookup(M_GETFIB(m), ip->ip_dst, 0, NHR_NONE, 0);
855 ICMPSTAT_INC(icps_noroute);
858 t = IA_SIN(ifatoia(nh->nh_ifa))->sin_addr;
861 mac_netinet_icmp_replyinplace(m);
864 ip->ip_ttl = V_ip_defttl;
872 * Retrieve any source routing from the incoming packet;
873 * add on any record-route or timestamp options.
875 cp = (u_char *) (ip + 1);
876 if ((opts = ip_srcroute(m)) == NULL &&
877 (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
878 opts->m_len = sizeof(struct in_addr);
879 mtod(opts, struct in_addr *)->s_addr = 0;
884 printf("icmp_reflect optlen %d rt %d => ",
885 optlen, opts->m_len);
887 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
888 opt = cp[IPOPT_OPTVAL];
889 if (opt == IPOPT_EOL)
891 if (opt == IPOPT_NOP)
894 if (cnt < IPOPT_OLEN + sizeof(*cp))
896 len = cp[IPOPT_OLEN];
897 if (len < IPOPT_OLEN + sizeof(*cp) ||
902 * Should check for overflow, but it "can't happen"
904 if (opt == IPOPT_RR || opt == IPOPT_TS ||
905 opt == IPOPT_SECURITY) {
907 mtod(opts, caddr_t) + opts->m_len, len);
911 /* Terminate & pad, if necessary */
912 cnt = opts->m_len % 4;
914 for (; cnt < 4; cnt++) {
915 *(mtod(opts, caddr_t) + opts->m_len) =
922 printf("%d\n", opts->m_len);
927 m_tag_delete_nonpersistent(m);
928 m->m_flags &= ~(M_BCAST|M_MCAST);
936 * Verifies if redirect message is valid, according to RFC 1122
938 * @src: sockaddr with address of redirect originator
939 * @dst: sockaddr with destination in question
940 * @gateway: new proposed gateway
942 * Returns 0 on success.
945 icmp_verify_redirect_gateway(struct sockaddr_in *src, struct sockaddr_in *dst,
946 struct sockaddr_in *gateway, u_int fibnum)
948 struct nhop_object *nh;
953 /* Verify the gateway is directly reachable. */
954 if ((ifa = ifa_ifwithnet((struct sockaddr *)gateway, 0, fibnum))==NULL)
955 return (ENETUNREACH);
957 /* TODO: fib-aware. */
958 if (ifa_ifwithaddr_check((struct sockaddr *)gateway))
959 return (EHOSTUNREACH);
961 nh = fib4_lookup(fibnum, dst->sin_addr, 0, NHR_NONE, 0);
966 * If the redirect isn't from our current router for this dst,
967 * it's either old or wrong. If it redirects us to ourselves,
968 * we have a routing loop, perhaps as a result of an interface
969 * going down recently.
971 if (!sa_equal((struct sockaddr *)src, &nh->gw_sa))
973 if (nh->nh_ifa != ifa && ifa->ifa_addr->sa_family != AF_LINK)
976 /* If host route already exists, ignore redirect. */
977 if (nh->nh_flags & NHF_HOST)
980 /* If the prefix is directly reachable, ignore redirect. */
981 if (!(nh->nh_flags & NHF_GATEWAY))
988 * Send an icmp packet back to the ip level,
989 * after supplying a checksum.
992 icmp_send(struct mbuf *m, struct mbuf *opts)
994 struct ip *ip = mtod(m, struct ip *);
998 hlen = ip->ip_hl << 2;
1001 icp = mtod(m, struct icmp *);
1002 icp->icmp_cksum = 0;
1003 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
1006 m->m_pkthdr.rcvif = (struct ifnet *)0;
1009 char dstbuf[INET_ADDRSTRLEN];
1010 char srcbuf[INET_ADDRSTRLEN];
1012 printf("icmp_send dst %s src %s\n",
1013 inet_ntoa_r(ip->ip_dst, dstbuf),
1014 inet_ntoa_r(ip->ip_src, srcbuf));
1017 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
1021 * Return milliseconds since 00:00 UTC in network format.
1030 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
1035 * Return the next larger or smaller MTU plateau (table from RFC 1191)
1036 * given current value MTU. If DIR is less than zero, a larger plateau
1037 * is returned; otherwise, a smaller value is returned.
1040 ip_next_mtu(int mtu, int dir)
1042 static int mtutab[] = {
1043 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
1048 size = (sizeof mtutab) / (sizeof mtutab[0]);
1050 for (i = 0; i < size; i++)
1051 if (mtu > mtutab[i])
1054 for (i = size - 1; i >= 0; i--)
1055 if (mtu < mtutab[i])
1057 if (mtu == mtutab[0])
1065 * badport_bandlim() - check for ICMP bandwidth limit
1067 * Return 0 if it is ok to send an ICMP error response, -1 if we have
1068 * hit our bandwidth limit and it is not ok.
1070 * If icmplim is <= 0, the feature is disabled and 0 is returned.
1072 * For now we separate the TCP and UDP subsystems w/ different 'which'
1073 * values. We may eventually remove this separation (and simplify the
1076 * Note that the printing of the error message is delayed so we can
1077 * properly print the icmp error rate that the system was trying to do
1078 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
1079 * the 'final' error, but it doesn't make sense to solve the printing
1080 * delay with more complex code.
1084 struct counter_rate cr;
1086 VNET_DEFINE_STATIC(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = {
1087 { "icmp unreach response" },
1088 { "icmp ping response" },
1089 { "icmp tstamp response" },
1090 { "closed port RST response" },
1091 { "open port RST response" },
1092 { "icmp6 unreach response" },
1093 { "sctp ootb response" }
1095 #define V_icmp_rates VNET(icmp_rates)
1098 icmp_bandlimit_init(void)
1101 for (int i = 0; i < BANDLIM_MAX; i++) {
1102 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK);
1103 V_icmp_rates[i].cr.cr_ticks = ticks;
1106 VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY,
1107 icmp_bandlimit_init, NULL);
1110 icmp_bandlimit_uninit(void)
1113 for (int i = 0; i < BANDLIM_MAX; i++)
1114 counter_u64_free(V_icmp_rates[i].cr.cr_rate);
1116 VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1117 icmp_bandlimit_uninit, NULL);
1120 badport_bandlim(int which)
1124 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED)
1127 KASSERT(which >= 0 && which < BANDLIM_MAX,
1128 ("%s: which %d", __func__, which));
1130 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim);
1133 if (pps > 0 && V_icmplim_output)
1134 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n",
1135 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim);