2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1982, 1986, 1988, 1993
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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/sysctl.h>
48 #include <sys/syslog.h>
51 #include <net/if_var.h>
52 #include <net/if_types.h>
53 #include <net/route.h>
54 #include <net/route/route_ctl.h>
55 #include <net/route/nhop.h>
58 #include <netinet/in.h>
59 #include <netinet/in_fib.h>
60 #include <netinet/in_pcb.h>
61 #include <netinet/in_systm.h>
62 #include <netinet/in_var.h>
63 #include <netinet/ip.h>
64 #include <netinet/ip_icmp.h>
65 #include <netinet/ip_var.h>
66 #include <netinet/ip_options.h>
67 #include <netinet/sctp.h>
68 #include <netinet/tcp.h>
69 #include <netinet/tcp_var.h>
70 #include <netinet/tcpip.h>
71 #include <netinet/icmp_var.h>
75 #include <machine/in_cksum.h>
77 #include <security/mac/mac_framework.h>
81 * ICMP routines: error generation, receive packet processing, and
82 * routines to turnaround packets back to the originator, and
83 * host table maintenance routines.
85 VNET_DEFINE_STATIC(int, icmplim) = 200;
86 #define V_icmplim VNET(icmplim)
87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW,
88 &VNET_NAME(icmplim), 0,
89 "Maximum number of ICMP responses per second");
91 VNET_DEFINE_STATIC(int, icmplim_curr_jitter) = 0;
92 #define V_icmplim_curr_jitter VNET(icmplim_curr_jitter)
93 VNET_DEFINE_STATIC(int, icmplim_jitter) = 16;
94 #define V_icmplim_jitter VNET(icmplim_jitter)
95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_jitter, CTLFLAG_VNET | CTLFLAG_RW,
96 &VNET_NAME(icmplim_jitter), 0,
97 "Random icmplim jitter adjustment limit");
99 VNET_DEFINE_STATIC(int, icmplim_output) = 1;
100 #define V_icmplim_output VNET(icmplim_output)
101 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW,
102 &VNET_NAME(icmplim_output), 0,
103 "Enable logging of ICMP response rate limiting");
106 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat);
107 VNET_PCPUSTAT_SYSINIT(icmpstat);
108 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat,
109 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)");
112 VNET_PCPUSTAT_SYSUNINIT(icmpstat);
115 VNET_DEFINE_STATIC(int, icmpmaskrepl) = 0;
116 #define V_icmpmaskrepl VNET(icmpmaskrepl)
117 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW,
118 &VNET_NAME(icmpmaskrepl), 0,
119 "Reply to ICMP Address Mask Request packets");
121 VNET_DEFINE_STATIC(u_int, icmpmaskfake) = 0;
122 #define V_icmpmaskfake VNET(icmpmaskfake)
123 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW,
124 &VNET_NAME(icmpmaskfake), 0,
125 "Fake reply to ICMP Address Mask Request packets");
127 VNET_DEFINE(int, drop_redirect) = 0;
128 #define V_drop_redirect VNET(drop_redirect)
129 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW,
130 &VNET_NAME(drop_redirect), 0,
131 "Ignore ICMP redirects");
133 VNET_DEFINE_STATIC(int, log_redirect) = 0;
134 #define V_log_redirect VNET(log_redirect)
135 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW,
136 &VNET_NAME(log_redirect), 0,
137 "Log ICMP redirects to the console");
139 VNET_DEFINE_STATIC(int, redirtimeout) = 60 * 10; /* 10 minutes */
140 #define V_redirtimeout VNET(redirtimeout)
141 SYSCTL_INT(_net_inet_icmp, OID_AUTO, redirtimeout, CTLFLAG_VNET | CTLFLAG_RW,
142 &VNET_NAME(redirtimeout), 0,
143 "Delay in seconds before expiring redirect route");
145 VNET_DEFINE_STATIC(char, reply_src[IFNAMSIZ]);
146 #define V_reply_src VNET(reply_src)
147 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW,
148 &VNET_NAME(reply_src), IFNAMSIZ,
149 "ICMP reply source for non-local packets");
151 VNET_DEFINE_STATIC(int, icmp_rfi) = 0;
152 #define V_icmp_rfi VNET(icmp_rfi)
153 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW,
154 &VNET_NAME(icmp_rfi), 0,
155 "ICMP reply from incoming interface for non-local packets");
156 /* Router requirements RFC 1812 section 4.3.2.3 requires 576 - 28. */
157 VNET_DEFINE_STATIC(int, icmp_quotelen) = 548;
158 #define V_icmp_quotelen VNET(icmp_quotelen)
159 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW,
160 &VNET_NAME(icmp_quotelen), 0,
161 "Number of bytes from original packet to quote in ICMP reply");
163 VNET_DEFINE_STATIC(int, icmpbmcastecho) = 0;
164 #define V_icmpbmcastecho VNET(icmpbmcastecho)
165 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW,
166 &VNET_NAME(icmpbmcastecho), 0,
167 "Reply to multicast ICMP Echo Request and Timestamp packets");
169 VNET_DEFINE_STATIC(int, icmptstamprepl) = 1;
170 #define V_icmptstamprepl VNET(icmptstamprepl)
171 SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_VNET | CTLFLAG_RW,
172 &VNET_NAME(icmptstamprepl), 0,
173 "Respond to ICMP Timestamp packets");
175 VNET_DEFINE_STATIC(int, error_keeptags) = 0;
176 #define V_error_keeptags VNET(error_keeptags)
177 SYSCTL_INT(_net_inet_icmp, OID_AUTO, error_keeptags, CTLFLAG_VNET | CTLFLAG_RW,
178 &VNET_NAME(error_keeptags), 0,
179 "ICMP error response keeps copy of mbuf_tags of original packet");
185 static void icmp_reflect(struct mbuf *);
186 static void icmp_send(struct mbuf *, struct mbuf *);
187 static int icmp_verify_redirect_gateway(struct sockaddr_in *,
188 struct sockaddr_in *, struct sockaddr_in *, u_int);
190 extern struct protosw inetsw[];
193 * Kernel module interface for updating icmpstat. The argument is an index
194 * into icmpstat treated as an array of u_long. While this encodes the
195 * general layout of icmpstat into the caller, it doesn't encode its
196 * location, so that future changes to add, for example, per-CPU stats
197 * support won't cause binary compatibility problems for kernel modules.
200 kmod_icmpstat_inc(int statnum)
203 counter_u64_add(VNET(icmpstat)[statnum], 1);
207 * Generate an error packet of type error
208 * in response to bad packet ip.
211 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
213 struct ip *oip, *nip;
216 unsigned icmplen, icmpelen, nlen, oiphlen;
218 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type",
221 if (type != ICMP_REDIRECT)
222 ICMPSTAT_INC(icps_error);
225 * if the original packet was encrypted.
226 * if not the first fragment of message.
227 * in response to a multicast or broadcast packet.
228 * if the old packet protocol was an ICMP error message.
230 if (n->m_flags & M_DECRYPTED)
232 if (n->m_flags & (M_BCAST|M_MCAST))
235 /* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */
236 if (n->m_len < sizeof(struct ip) + ICMP_MINLEN)
238 oip = mtod(n, struct ip *);
239 oiphlen = oip->ip_hl << 2;
240 if (n->m_len < oiphlen + ICMP_MINLEN)
244 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
246 if (oip->ip_off & htons(~(IP_MF|IP_DF)))
248 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
249 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip +
250 oiphlen))->icmp_type)) {
251 ICMPSTAT_INC(icps_oldicmp);
255 * Calculate length to quote from original packet and
256 * prevent the ICMP mbuf from overflowing.
257 * Unfortunately this is non-trivial since ip_forward()
258 * sends us truncated packets.
260 nlen = m_length(n, NULL);
261 if (oip->ip_p == IPPROTO_TCP) {
265 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
268 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
269 (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)
271 oip = mtod(n, struct ip *);
272 th = mtodo(n, oiphlen);
273 tcphlen = th->th_off << 2;
274 if (tcphlen < sizeof(struct tcphdr))
276 if (ntohs(oip->ip_len) < oiphlen + tcphlen)
278 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
280 if (n->m_len < oiphlen + tcphlen &&
281 (n = m_pullup(n, oiphlen + tcphlen)) == NULL)
283 oip = mtod(n, struct ip *);
284 icmpelen = max(tcphlen, min(V_icmp_quotelen,
285 ntohs(oip->ip_len) - oiphlen));
286 } else if (oip->ip_p == IPPROTO_SCTP) {
288 struct sctp_chunkhdr *ch;
290 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr))
292 if (oiphlen + sizeof(struct sctphdr) > n->m_len &&
295 if (n->m_len < oiphlen + sizeof(struct sctphdr) &&
296 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL)
298 oip = mtod(n, struct ip *);
299 icmpelen = max(sizeof(struct sctphdr),
300 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
301 sh = mtodo(n, oiphlen);
302 if (ntohl(sh->v_tag) == 0 &&
303 ntohs(oip->ip_len) >= oiphlen +
304 sizeof(struct sctphdr) + 8 &&
305 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 ||
306 n->m_next != NULL)) {
307 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 &&
308 (n = m_pullup(n, oiphlen +
309 sizeof(struct sctphdr) + 8)) == NULL)
311 oip = mtod(n, struct ip *);
312 sh = mtodo(n, oiphlen);
313 ch = (struct sctp_chunkhdr *)(sh + 1);
314 if (ch->chunk_type == SCTP_INITIATION) {
315 icmpelen = max(sizeof(struct sctphdr) + 8,
316 min(V_icmp_quotelen, ntohs(oip->ip_len) -
321 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) -
324 icmplen = min(oiphlen + icmpelen, nlen);
325 if (icmplen < sizeof(struct ip))
328 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
329 m = m_gethdr(M_NOWAIT, MT_DATA);
331 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
335 mac_netinet_icmp_reply(n, m);
337 icmplen = min(icmplen, M_TRAILINGSPACE(m) -
338 sizeof(struct ip) - ICMP_MINLEN);
339 m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen);
340 m->m_data += sizeof(struct ip);
341 m->m_len = ICMP_MINLEN + icmplen;
343 /* XXX MRT make the outgoing packet use the same FIB
344 * that was associated with the incoming packet
346 M_SETFIB(m, M_GETFIB(n));
347 icp = mtod(m, struct icmp *);
348 ICMPSTAT_INC(icps_outhist[type]);
349 icp->icmp_type = type;
350 if (type == ICMP_REDIRECT)
351 icp->icmp_gwaddr.s_addr = dest;
355 * The following assignments assume an overlay with the
356 * just zeroed icmp_void field.
358 if (type == ICMP_PARAMPROB) {
359 icp->icmp_pptr = code;
361 } else if (type == ICMP_UNREACH &&
362 code == ICMP_UNREACH_NEEDFRAG && mtu) {
363 icp->icmp_nextmtu = htons(mtu);
366 icp->icmp_code = code;
369 * Copy the quotation into ICMP message and
370 * convert quoted IP header back to network representation.
372 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
376 * Set up ICMP message mbuf and copy old IP header (without options
377 * in front of ICMP message.
378 * If the original mbuf was meant to bypass the firewall, the error
379 * reply should bypass as well.
381 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
382 KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip),
383 ("insufficient space for ip header"));
384 m->m_data -= sizeof(struct ip);
385 m->m_len += sizeof(struct ip);
386 m->m_pkthdr.len = m->m_len;
387 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
388 nip = mtod(m, struct ip *);
389 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
390 nip->ip_len = htons(m->m_len);
391 nip->ip_v = IPVERSION;
393 nip->ip_p = IPPROTO_ICMP;
397 if (V_error_keeptags)
398 m_tag_copy_chain(m, n, M_NOWAIT);
407 * Process a received ICMP message.
410 icmp_input(struct mbuf **mp, int *offp, int proto)
413 struct in_ifaddr *ia;
414 struct mbuf *m = *mp;
415 struct ip *ip = mtod(m, struct ip *);
416 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
418 int icmplen = ntohs(ip->ip_len) - *offp;
420 void (*ctlfunc)(int, struct sockaddr *, void *);
428 * Locate icmp structure in mbuf, and check
429 * that not corrupted and of at least minimum length.
433 char srcbuf[INET_ADDRSTRLEN];
434 char dstbuf[INET_ADDRSTRLEN];
436 printf("icmp_input from %s to %s, len %d\n",
437 inet_ntoa_r(ip->ip_src, srcbuf),
438 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen);
441 if (icmplen < ICMP_MINLEN) {
442 ICMPSTAT_INC(icps_tooshort);
445 i = hlen + min(icmplen, ICMP_ADVLENMIN);
446 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
447 ICMPSTAT_INC(icps_tooshort);
448 return (IPPROTO_DONE);
450 ip = mtod(m, struct ip *);
453 icp = mtod(m, struct icmp *);
454 if (in_cksum(m, icmplen)) {
455 ICMPSTAT_INC(icps_checksum);
463 printf("icmp_input, type %d code %d\n", icp->icmp_type,
468 * Message type specific processing.
470 if (icp->icmp_type > ICMP_MAXTYPE)
474 bzero(&icmpsrc, sizeof(icmpsrc));
475 icmpsrc.sin_len = sizeof(struct sockaddr_in);
476 icmpsrc.sin_family = AF_INET;
477 bzero(&icmpdst, sizeof(icmpdst));
478 icmpdst.sin_len = sizeof(struct sockaddr_in);
479 icmpdst.sin_family = AF_INET;
480 bzero(&icmpgw, sizeof(icmpgw));
481 icmpgw.sin_len = sizeof(struct sockaddr_in);
482 icmpgw.sin_family = AF_INET;
484 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
485 code = icp->icmp_code;
486 switch (icp->icmp_type) {
489 case ICMP_UNREACH_NET:
490 case ICMP_UNREACH_HOST:
491 case ICMP_UNREACH_SRCFAIL:
492 case ICMP_UNREACH_NET_UNKNOWN:
493 case ICMP_UNREACH_HOST_UNKNOWN:
494 case ICMP_UNREACH_ISOLATED:
495 case ICMP_UNREACH_TOSNET:
496 case ICMP_UNREACH_TOSHOST:
497 case ICMP_UNREACH_HOST_PRECEDENCE:
498 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
499 code = PRC_UNREACH_NET;
502 case ICMP_UNREACH_NEEDFRAG:
507 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
508 * Treat subcodes 2,3 as immediate RST
510 case ICMP_UNREACH_PROTOCOL:
511 code = PRC_UNREACH_PROTOCOL;
513 case ICMP_UNREACH_PORT:
514 code = PRC_UNREACH_PORT;
517 case ICMP_UNREACH_NET_PROHIB:
518 case ICMP_UNREACH_HOST_PROHIB:
519 case ICMP_UNREACH_FILTER_PROHIB:
520 code = PRC_UNREACH_ADMIN_PROHIB;
531 code += PRC_TIMXCEED_INTRANS;
537 code = PRC_PARAMPROB;
540 * Problem with datagram; advise higher level routines.
542 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
543 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
544 ICMPSTAT_INC(icps_badlen);
547 /* Discard ICMP's in response to multicast packets */
548 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
552 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
554 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
556 * XXX if the packet contains [IPv4 AH TCP], we can't make a
557 * notification to TCP layer.
559 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp));
561 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
562 /* This should actually not happen */
563 ICMPSTAT_INC(icps_tooshort);
564 return (IPPROTO_DONE);
566 ip = mtod(m, struct ip *);
567 icp = (struct icmp *)(ip + 1);
569 * The upper layer handler can rely on:
570 * - The outer IP header has no options.
571 * - The outer IP header, the ICMP header, the inner IP header,
572 * and the first n bytes of the inner payload are contiguous.
573 * n is at least 8, but might be larger based on
574 * ICMP_ADVLENPREF. See its definition in ip_icmp.h.
576 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
578 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
579 (void *)&icp->icmp_ip);
583 ICMPSTAT_INC(icps_badcode);
587 if (!V_icmpbmcastecho
588 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
589 ICMPSTAT_INC(icps_bmcastecho);
592 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
594 icp->icmp_type = ICMP_ECHOREPLY;
598 if (V_icmptstamprepl == 0)
600 if (!V_icmpbmcastecho
601 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
602 ICMPSTAT_INC(icps_bmcasttstamp);
605 if (icmplen < ICMP_TSLEN) {
606 ICMPSTAT_INC(icps_badlen);
609 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
611 icp->icmp_type = ICMP_TSTAMPREPLY;
612 icp->icmp_rtime = iptime();
613 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
617 if (V_icmpmaskrepl == 0)
620 * We are not able to respond with all ones broadcast
621 * unless we receive it over a point-to-point interface.
623 if (icmplen < ICMP_MASKLEN)
625 switch (ip->ip_dst.s_addr) {
626 case INADDR_BROADCAST:
628 icmpdst.sin_addr = ip->ip_src;
632 icmpdst.sin_addr = ip->ip_dst;
634 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
635 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
638 if (ia->ia_ifp == NULL)
640 icp->icmp_type = ICMP_MASKREPLY;
641 if (V_icmpmaskfake == 0)
642 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
644 icp->icmp_mask = V_icmpmaskfake;
645 if (ip->ip_src.s_addr == 0) {
646 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
647 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
648 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
649 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
652 ICMPSTAT_INC(icps_reflect);
653 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
655 return (IPPROTO_DONE);
658 if (V_log_redirect) {
661 src = ntohl(ip->ip_src.s_addr);
662 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
663 gw = ntohl(icp->icmp_gwaddr.s_addr);
664 printf("icmp redirect from %d.%d.%d.%d: "
665 "%d.%d.%d.%d => %d.%d.%d.%d\n",
666 (int)(src >> 24), (int)((src >> 16) & 0xff),
667 (int)((src >> 8) & 0xff), (int)(src & 0xff),
668 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
669 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
670 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
671 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
674 * RFC1812 says we must ignore ICMP redirects if we
675 * are acting as router.
677 if (V_drop_redirect || V_ipforwarding)
681 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
682 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
683 ICMPSTAT_INC(icps_badlen);
687 * Short circuit routing redirects to force
688 * immediate change in the kernel's routing
689 * tables. The message is also handed to anyone
690 * listening on a raw socket (e.g. the routing
691 * daemon for use in updating its tables).
693 icmpgw.sin_addr = ip->ip_src;
694 icmpdst.sin_addr = icp->icmp_gwaddr;
697 char dstbuf[INET_ADDRSTRLEN];
698 char gwbuf[INET_ADDRSTRLEN];
700 printf("redirect dst %s to %s\n",
701 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf),
702 inet_ntoa_r(icp->icmp_gwaddr, gwbuf));
705 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
708 * RFC 1122 says network (code 0,2) redirects SHOULD
709 * be treated identically to the host redirects.
710 * Given that, ignore network masks.
715 * icmpsrc: route destination
716 * icmpdst: route gateway
717 * icmpgw: message source
720 if (icmp_verify_redirect_gateway(&icmpgw, &icmpsrc, &icmpdst,
722 /* TODO: increment bad redirects here */
726 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
727 rib_add_redirect(fibnum, (struct sockaddr *)&icmpsrc,
728 (struct sockaddr *)&icmpdst,
729 (struct sockaddr *)&icmpgw, m->m_pkthdr.rcvif,
730 RTF_GATEWAY, V_redirtimeout);
732 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
736 * No kernel processing for the following;
737 * just fall through to send to raw listener.
740 case ICMP_ROUTERADVERT:
741 case ICMP_ROUTERSOLICIT:
742 case ICMP_TSTAMPREPLY:
745 case ICMP_SOURCEQUENCH:
752 rip_input(mp, offp, proto);
753 return (IPPROTO_DONE);
757 return (IPPROTO_DONE);
761 * Reflect the ip packet back to the source
764 icmp_reflect(struct mbuf *m)
766 struct ip *ip = mtod(m, struct ip *);
769 struct in_ifaddr *ia;
771 struct nhop_object *nh;
772 struct mbuf *opts = NULL;
773 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
777 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
778 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
779 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
780 m_freem(m); /* Bad return address */
781 ICMPSTAT_INC(icps_badaddr);
782 goto done; /* Ip_output() will check for broadcast */
786 ip->ip_dst = ip->ip_src;
789 * Source selection for ICMP replies:
791 * If the incoming packet was addressed directly to one of our
792 * own addresses, use dst as the src for the reply.
794 CK_LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
795 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
796 t = IA_SIN(ia)->sin_addr;
802 * If the incoming packet was addressed to one of our broadcast
803 * addresses, use the first non-broadcast address which corresponds
804 * to the incoming interface.
806 ifp = m->m_pkthdr.rcvif;
807 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
808 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
809 if (ifa->ifa_addr->sa_family != AF_INET)
812 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
814 t = IA_SIN(ia)->sin_addr;
820 * If the packet was transiting through us, use the address of
821 * the interface the packet came through in. If that interface
822 * doesn't have a suitable IP address, the normal selection
825 if (V_icmp_rfi && ifp != NULL) {
826 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
827 if (ifa->ifa_addr->sa_family != AF_INET)
830 t = IA_SIN(ia)->sin_addr;
835 * If the incoming packet was not addressed directly to us, use
836 * designated interface for icmp replies specified by sysctl
837 * net.inet.icmp.reply_src (default not set). Otherwise continue
838 * with normal source selection.
840 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
841 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
842 if (ifa->ifa_addr->sa_family != AF_INET)
845 t = IA_SIN(ia)->sin_addr;
850 * If the packet was transiting through us, use the address of
851 * the interface that is the closest to the packet source.
852 * When we don't have a route back to the packet source, stop here
853 * and drop the packet.
855 nh = fib4_lookup(M_GETFIB(m), ip->ip_dst, 0, NHR_NONE, 0);
858 ICMPSTAT_INC(icps_noroute);
861 t = IA_SIN(ifatoia(nh->nh_ifa))->sin_addr;
864 mac_netinet_icmp_replyinplace(m);
867 ip->ip_ttl = V_ip_defttl;
875 * Retrieve any source routing from the incoming packet;
876 * add on any record-route or timestamp options.
878 cp = (u_char *) (ip + 1);
879 if ((opts = ip_srcroute(m)) == NULL &&
880 (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
881 opts->m_len = sizeof(struct in_addr);
882 mtod(opts, struct in_addr *)->s_addr = 0;
887 printf("icmp_reflect optlen %d rt %d => ",
888 optlen, opts->m_len);
890 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
891 opt = cp[IPOPT_OPTVAL];
892 if (opt == IPOPT_EOL)
894 if (opt == IPOPT_NOP)
897 if (cnt < IPOPT_OLEN + sizeof(*cp))
899 len = cp[IPOPT_OLEN];
900 if (len < IPOPT_OLEN + sizeof(*cp) ||
905 * Should check for overflow, but it "can't happen"
907 if (opt == IPOPT_RR || opt == IPOPT_TS ||
908 opt == IPOPT_SECURITY) {
910 mtod(opts, caddr_t) + opts->m_len, len);
914 /* Terminate & pad, if necessary */
915 cnt = opts->m_len % 4;
917 for (; cnt < 4; cnt++) {
918 *(mtod(opts, caddr_t) + opts->m_len) =
925 printf("%d\n", opts->m_len);
930 m_tag_delete_nonpersistent(m);
931 m->m_flags &= ~(M_BCAST|M_MCAST);
939 * Verifies if redirect message is valid, according to RFC 1122
941 * @src: sockaddr with address of redirect originator
942 * @dst: sockaddr with destination in question
943 * @gateway: new proposed gateway
945 * Returns 0 on success.
948 icmp_verify_redirect_gateway(struct sockaddr_in *src, struct sockaddr_in *dst,
949 struct sockaddr_in *gateway, u_int fibnum)
951 struct nhop_object *nh;
956 /* Verify the gateway is directly reachable. */
957 if ((ifa = ifa_ifwithnet((struct sockaddr *)gateway, 0, fibnum))==NULL)
958 return (ENETUNREACH);
960 /* TODO: fib-aware. */
961 if (ifa_ifwithaddr_check((struct sockaddr *)gateway))
962 return (EHOSTUNREACH);
964 nh = fib4_lookup(fibnum, dst->sin_addr, 0, NHR_NONE, 0);
969 * If the redirect isn't from our current router for this dst,
970 * it's either old or wrong. If it redirects us to ourselves,
971 * we have a routing loop, perhaps as a result of an interface
972 * going down recently.
974 if (!sa_equal((struct sockaddr *)src, &nh->gw_sa))
976 if (nh->nh_ifa != ifa && ifa->ifa_addr->sa_family != AF_LINK)
979 /* If host route already exists, ignore redirect. */
980 if (nh->nh_flags & NHF_HOST)
983 /* If the prefix is directly reachable, ignore redirect. */
984 if (!(nh->nh_flags & NHF_GATEWAY))
991 * Send an icmp packet back to the ip level,
992 * after supplying a checksum.
995 icmp_send(struct mbuf *m, struct mbuf *opts)
997 struct ip *ip = mtod(m, struct ip *);
1001 hlen = ip->ip_hl << 2;
1004 icp = mtod(m, struct icmp *);
1005 icp->icmp_cksum = 0;
1006 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
1009 m->m_pkthdr.rcvif = (struct ifnet *)0;
1012 char dstbuf[INET_ADDRSTRLEN];
1013 char srcbuf[INET_ADDRSTRLEN];
1015 printf("icmp_send dst %s src %s\n",
1016 inet_ntoa_r(ip->ip_dst, dstbuf),
1017 inet_ntoa_r(ip->ip_src, srcbuf));
1020 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
1024 * Return milliseconds since 00:00 UTC in network format.
1033 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
1038 * Return the next larger or smaller MTU plateau (table from RFC 1191)
1039 * given current value MTU. If DIR is less than zero, a larger plateau
1040 * is returned; otherwise, a smaller value is returned.
1043 ip_next_mtu(int mtu, int dir)
1045 static int mtutab[] = {
1046 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
1051 size = (sizeof mtutab) / (sizeof mtutab[0]);
1053 for (i = 0; i < size; i++)
1054 if (mtu > mtutab[i])
1057 for (i = size - 1; i >= 0; i--)
1058 if (mtu < mtutab[i])
1060 if (mtu == mtutab[0])
1068 * badport_bandlim() - check for ICMP bandwidth limit
1070 * Return 0 if it is ok to send an ICMP error response, -1 if we have
1071 * hit our bandwidth limit and it is not ok.
1073 * If icmplim is <= 0, the feature is disabled and 0 is returned.
1075 * For now we separate the TCP and UDP subsystems w/ different 'which'
1076 * values. We may eventually remove this separation (and simplify the
1079 * Note that the printing of the error message is delayed so we can
1080 * properly print the icmp error rate that the system was trying to do
1081 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
1082 * the 'final' error, but it doesn't make sense to solve the printing
1083 * delay with more complex code.
1087 struct counter_rate cr;
1089 VNET_DEFINE_STATIC(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = {
1090 { "icmp unreach response" },
1091 { "icmp ping response" },
1092 { "icmp tstamp response" },
1093 { "closed port RST response" },
1094 { "open port RST response" },
1095 { "icmp6 unreach response" },
1096 { "sctp ootb response" }
1098 #define V_icmp_rates VNET(icmp_rates)
1101 icmp_bandlimit_init(void)
1104 for (int i = 0; i < BANDLIM_MAX; i++) {
1105 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK);
1106 V_icmp_rates[i].cr.cr_ticks = ticks;
1109 VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY,
1110 icmp_bandlimit_init, NULL);
1113 icmp_bandlimit_uninit(void)
1116 for (int i = 0; i < BANDLIM_MAX; i++)
1117 counter_u64_free(V_icmp_rates[i].cr.cr_rate);
1119 VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1120 icmp_bandlimit_uninit, NULL);
1123 badport_bandlim(int which)
1127 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED)
1130 KASSERT(which >= 0 && which < BANDLIM_MAX,
1131 ("%s: which %d", __func__, which));
1133 if ((V_icmplim + V_icmplim_curr_jitter) <= 0)
1134 V_icmplim_curr_jitter = -V_icmplim + 1;
1136 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim +
1137 V_icmplim_curr_jitter);
1140 * Adjust limit +/- to jitter the measurement to deny a
1141 * side-channel port scan as in CVE-2020-25705
1143 if (V_icmplim_jitter > 0) {
1145 arc4random_uniform(V_icmplim_jitter * 2 +1)
1148 V_icmplim_curr_jitter = inc;
1153 if (pps > 0 && V_icmplim_output)
1154 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n",
1155 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim +
1156 V_icmplim_curr_jitter);