FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_icmp.c
1 /*-
2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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.
16 *
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
27 * SUCH DAMAGE.
28 *
29 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
30 * $FreeBSD$
31 */
32
33 #include "opt_ipsec.h"
34 #include "opt_mac.h"
35
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/mac.h>
39 #include <sys/mbuf.h>
40 #include <sys/protosw.h>
41 #include <sys/socket.h>
42 #include <sys/time.h>
43 #include <sys/kernel.h>
44 #include <sys/sysctl.h>
45
46 #include <net/if.h>
47 #include <net/if_types.h>
48 #include <net/route.h>
49
50 #include <netinet/in.h>
51 #include <netinet/in_pcb.h>
52 #include <netinet/in_systm.h>
53 #include <netinet/in_var.h>
54 #include <netinet/ip.h>
55 #include <netinet/ip_icmp.h>
56 #include <netinet/ip_var.h>
57 #include <netinet/tcp.h>
58 #include <netinet/tcp_var.h>
59 #include <netinet/tcpip.h>
60 #include <netinet/icmp_var.h>
61
62 #ifdef IPSEC
63 #include <netinet6/ipsec.h>
64 #include <netkey/key.h>
65 #endif
66
67 #ifdef FAST_IPSEC
68 #include <netipsec/ipsec.h>
69 #include <netipsec/key.h>
70 #define IPSEC
71 #endif
72
73 #include <machine/in_cksum.h>
74
75 /*
76 * ICMP routines: error generation, receive packet processing, and
77 * routines to turnaround packets back to the originator, and
78 * host table maintenance routines.
79 */
80
81 struct icmpstat icmpstat;
82 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
83 &icmpstat, icmpstat, "");
84
85 static int icmpmaskrepl = 0;
86 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
87 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets.");
88
89 static u_int icmpmaskfake = 0;
90 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
91 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets.");
92
93 static int drop_redirect = 0;
94 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
95 &drop_redirect, 0, "");
96
97 static int log_redirect = 0;
98 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
99 &log_redirect, 0, "");
100
101 static int icmplim = 200;
102 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
103 &icmplim, 0, "");
104
105 static int icmplim_output = 1;
106 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
107 &icmplim_output, 0, "");
108
109 static char reply_src[IFNAMSIZ];
110 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
111 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets.");
112
113 /*
114 * ICMP broadcast echo sysctl
115 */
116
117 static int icmpbmcastecho = 0;
118 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
119 &icmpbmcastecho, 0, "");
120
121
122 #ifdef ICMPPRINTFS
123 int icmpprintfs = 0;
124 #endif
125
126 static void icmp_reflect(struct mbuf *);
127 static void icmp_send(struct mbuf *, struct mbuf *);
128
129 extern struct protosw inetsw[];
130
131 /*
132 * Generate an error packet of type error
133 * in response to bad packet ip.
134 */
135 void
136 icmp_error(n, type, code, dest, destifp)
137 struct mbuf *n;
138 int type, code;
139 n_long dest;
140 struct ifnet *destifp;
141 {
142 register struct ip *oip = mtod(n, struct ip *), *nip;
143 register unsigned oiplen = oip->ip_hl << 2;
144 register struct icmp *icp;
145 register struct mbuf *m;
146 unsigned icmplen;
147
148 #ifdef ICMPPRINTFS
149 if (icmpprintfs)
150 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
151 #endif
152 if (type != ICMP_REDIRECT)
153 icmpstat.icps_error++;
154 /*
155 * Don't send error if the original packet was encrypted.
156 * Don't send error if not the first fragment of message.
157 * Don't error if the old packet protocol was ICMP
158 * error message, only known informational types.
159 */
160 if (n->m_flags & M_DECRYPTED)
161 goto freeit;
162 if (oip->ip_off &~ (IP_MF|IP_DF))
163 goto freeit;
164 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
165 n->m_len >= oiplen + ICMP_MINLEN &&
166 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
167 icmpstat.icps_oldicmp++;
168 goto freeit;
169 }
170 /* Don't send error in response to a multicast or broadcast packet */
171 if (n->m_flags & (M_BCAST|M_MCAST))
172 goto freeit;
173 /*
174 * First, formulate icmp message
175 */
176 m = m_gethdr(M_DONTWAIT, MT_HEADER);
177 if (m == NULL)
178 goto freeit;
179 #ifdef MAC
180 mac_create_mbuf_netlayer(n, m);
181 #endif
182 icmplen = min(oiplen + 8, oip->ip_len);
183 if (icmplen < sizeof(struct ip))
184 panic("icmp_error: bad length");
185 m->m_len = icmplen + ICMP_MINLEN;
186 MH_ALIGN(m, m->m_len);
187 icp = mtod(m, struct icmp *);
188 if ((u_int)type > ICMP_MAXTYPE)
189 panic("icmp_error");
190 icmpstat.icps_outhist[type]++;
191 icp->icmp_type = type;
192 if (type == ICMP_REDIRECT)
193 icp->icmp_gwaddr.s_addr = dest;
194 else {
195 icp->icmp_void = 0;
196 /*
197 * The following assignments assume an overlay with the
198 * zeroed icmp_void field.
199 */
200 if (type == ICMP_PARAMPROB) {
201 icp->icmp_pptr = code;
202 code = 0;
203 } else if (type == ICMP_UNREACH &&
204 code == ICMP_UNREACH_NEEDFRAG && destifp) {
205 icp->icmp_nextmtu = htons(destifp->if_mtu);
206 }
207 }
208
209 icp->icmp_code = code;
210 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
211 nip = &icp->icmp_ip;
212
213 /*
214 * Convert fields to network representation.
215 */
216 nip->ip_len = htons(nip->ip_len);
217 nip->ip_off = htons(nip->ip_off);
218
219 /*
220 * Now, copy old ip header (without options)
221 * in front of icmp message.
222 */
223 if (m->m_data - sizeof(struct ip) < m->m_pktdat)
224 panic("icmp len");
225 /*
226 * If the original mbuf was meant to bypass the firewall, the error
227 * reply should bypass as well.
228 */
229 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
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_v = IPVERSION;
238 nip->ip_hl = 5;
239 nip->ip_p = IPPROTO_ICMP;
240 nip->ip_tos = 0;
241 icmp_reflect(m);
242
243 freeit:
244 m_freem(n);
245 }
246
247 /*
248 * Process a received ICMP message.
249 */
250 void
251 icmp_input(m, off)
252 struct mbuf *m;
253 int off;
254 {
255 struct icmp *icp;
256 struct in_ifaddr *ia;
257 struct ip *ip = mtod(m, struct ip *);
258 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
259 int hlen = off;
260 int icmplen = ip->ip_len;
261 int i, code;
262 void (*ctlfunc)(int, struct sockaddr *, void *);
263
264 /*
265 * Locate icmp structure in mbuf, and check
266 * that not corrupted and of at least minimum length.
267 */
268 #ifdef ICMPPRINTFS
269 if (icmpprintfs) {
270 char buf[4 * sizeof "123"];
271 strcpy(buf, inet_ntoa(ip->ip_src));
272 printf("icmp_input from %s to %s, len %d\n",
273 buf, inet_ntoa(ip->ip_dst), icmplen);
274 }
275 #endif
276 if (icmplen < ICMP_MINLEN) {
277 icmpstat.icps_tooshort++;
278 goto freeit;
279 }
280 i = hlen + min(icmplen, ICMP_ADVLENMIN);
281 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
282 icmpstat.icps_tooshort++;
283 return;
284 }
285 ip = mtod(m, struct ip *);
286 m->m_len -= hlen;
287 m->m_data += hlen;
288 icp = mtod(m, struct icmp *);
289 if (in_cksum(m, icmplen)) {
290 icmpstat.icps_checksum++;
291 goto freeit;
292 }
293 m->m_len += hlen;
294 m->m_data -= hlen;
295
296 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
297 /*
298 * Deliver very specific ICMP type only.
299 */
300 switch (icp->icmp_type) {
301 case ICMP_UNREACH:
302 case ICMP_TIMXCEED:
303 break;
304 default:
305 goto freeit;
306 }
307 }
308
309 #ifdef ICMPPRINTFS
310 if (icmpprintfs)
311 printf("icmp_input, type %d code %d\n", icp->icmp_type,
312 icp->icmp_code);
313 #endif
314
315 /*
316 * Message type specific processing.
317 */
318 if (icp->icmp_type > ICMP_MAXTYPE)
319 goto raw;
320
321 /* Initialize */
322 bzero(&icmpsrc, sizeof(icmpsrc));
323 icmpsrc.sin_len = sizeof(struct sockaddr_in);
324 icmpsrc.sin_family = AF_INET;
325 bzero(&icmpdst, sizeof(icmpdst));
326 icmpdst.sin_len = sizeof(struct sockaddr_in);
327 icmpdst.sin_family = AF_INET;
328 bzero(&icmpgw, sizeof(icmpgw));
329 icmpgw.sin_len = sizeof(struct sockaddr_in);
330 icmpgw.sin_family = AF_INET;
331
332 icmpstat.icps_inhist[icp->icmp_type]++;
333 code = icp->icmp_code;
334 switch (icp->icmp_type) {
335
336 case ICMP_UNREACH:
337 switch (code) {
338 case ICMP_UNREACH_NET:
339 case ICMP_UNREACH_HOST:
340 case ICMP_UNREACH_SRCFAIL:
341 case ICMP_UNREACH_NET_UNKNOWN:
342 case ICMP_UNREACH_HOST_UNKNOWN:
343 case ICMP_UNREACH_ISOLATED:
344 case ICMP_UNREACH_TOSNET:
345 case ICMP_UNREACH_TOSHOST:
346 case ICMP_UNREACH_HOST_PRECEDENCE:
347 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
348 code = PRC_UNREACH_NET;
349 break;
350
351 case ICMP_UNREACH_NEEDFRAG:
352 code = PRC_MSGSIZE;
353 break;
354
355 /*
356 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
357 * Treat subcodes 2,3 as immediate RST
358 */
359 case ICMP_UNREACH_PROTOCOL:
360 case ICMP_UNREACH_PORT:
361 code = PRC_UNREACH_PORT;
362 break;
363
364 case ICMP_UNREACH_NET_PROHIB:
365 case ICMP_UNREACH_HOST_PROHIB:
366 case ICMP_UNREACH_FILTER_PROHIB:
367 code = PRC_UNREACH_ADMIN_PROHIB;
368 break;
369
370 default:
371 goto badcode;
372 }
373 goto deliver;
374
375 case ICMP_TIMXCEED:
376 if (code > 1)
377 goto badcode;
378 code += PRC_TIMXCEED_INTRANS;
379 goto deliver;
380
381 case ICMP_PARAMPROB:
382 if (code > 1)
383 goto badcode;
384 code = PRC_PARAMPROB;
385 goto deliver;
386
387 case ICMP_SOURCEQUENCH:
388 if (code)
389 goto badcode;
390 code = PRC_QUENCH;
391 deliver:
392 /*
393 * Problem with datagram; advise higher level routines.
394 */
395 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
396 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
397 icmpstat.icps_badlen++;
398 goto freeit;
399 }
400 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
401 /* Discard ICMP's in response to multicast packets */
402 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
403 goto badcode;
404 #ifdef ICMPPRINTFS
405 if (icmpprintfs)
406 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
407 #endif
408 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
409 /*
410 * XXX if the packet contains [IPv4 AH TCP], we can't make a
411 * notification to TCP layer.
412 */
413 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
414 if (ctlfunc)
415 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
416 (void *)&icp->icmp_ip);
417 break;
418
419 badcode:
420 icmpstat.icps_badcode++;
421 break;
422
423 case ICMP_ECHO:
424 if (!icmpbmcastecho
425 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
426 icmpstat.icps_bmcastecho++;
427 break;
428 }
429 icp->icmp_type = ICMP_ECHOREPLY;
430 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
431 goto freeit;
432 else
433 goto reflect;
434
435 case ICMP_TSTAMP:
436 if (!icmpbmcastecho
437 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
438 icmpstat.icps_bmcasttstamp++;
439 break;
440 }
441 if (icmplen < ICMP_TSLEN) {
442 icmpstat.icps_badlen++;
443 break;
444 }
445 icp->icmp_type = ICMP_TSTAMPREPLY;
446 icp->icmp_rtime = iptime();
447 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
448 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
449 goto freeit;
450 else
451 goto reflect;
452
453 case ICMP_MASKREQ:
454 if (icmpmaskrepl == 0)
455 break;
456 /*
457 * We are not able to respond with all ones broadcast
458 * unless we receive it over a point-to-point interface.
459 */
460 if (icmplen < ICMP_MASKLEN)
461 break;
462 switch (ip->ip_dst.s_addr) {
463
464 case INADDR_BROADCAST:
465 case INADDR_ANY:
466 icmpdst.sin_addr = ip->ip_src;
467 break;
468
469 default:
470 icmpdst.sin_addr = ip->ip_dst;
471 }
472 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
473 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
474 if (ia == 0)
475 break;
476 if (ia->ia_ifp == 0)
477 break;
478 icp->icmp_type = ICMP_MASKREPLY;
479 if (icmpmaskfake == 0)
480 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
481 else
482 icp->icmp_mask = icmpmaskfake;
483 if (ip->ip_src.s_addr == 0) {
484 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
485 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
486 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
487 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
488 }
489 reflect:
490 ip->ip_len += hlen; /* since ip_input deducts this */
491 icmpstat.icps_reflect++;
492 icmpstat.icps_outhist[icp->icmp_type]++;
493 icmp_reflect(m);
494 return;
495
496 case ICMP_REDIRECT:
497 if (log_redirect) {
498 u_long src, dst, gw;
499
500 src = ntohl(ip->ip_src.s_addr);
501 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
502 gw = ntohl(icp->icmp_gwaddr.s_addr);
503 printf("icmp redirect from %d.%d.%d.%d: "
504 "%d.%d.%d.%d => %d.%d.%d.%d\n",
505 (int)(src >> 24), (int)((src >> 16) & 0xff),
506 (int)((src >> 8) & 0xff), (int)(src & 0xff),
507 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
508 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
509 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
510 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
511 }
512 /*
513 * RFC1812 says we must ignore ICMP redirects if we
514 * are acting as router.
515 */
516 if (drop_redirect || ipforwarding)
517 break;
518 if (code > 3)
519 goto badcode;
520 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
521 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
522 icmpstat.icps_badlen++;
523 break;
524 }
525 /*
526 * Short circuit routing redirects to force
527 * immediate change in the kernel's routing
528 * tables. The message is also handed to anyone
529 * listening on a raw socket (e.g. the routing
530 * daemon for use in updating its tables).
531 */
532 icmpgw.sin_addr = ip->ip_src;
533 icmpdst.sin_addr = icp->icmp_gwaddr;
534 #ifdef ICMPPRINTFS
535 if (icmpprintfs) {
536 char buf[4 * sizeof "123"];
537 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
538
539 printf("redirect dst %s to %s\n",
540 buf, inet_ntoa(icp->icmp_gwaddr));
541 }
542 #endif
543 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
544 rtredirect((struct sockaddr *)&icmpsrc,
545 (struct sockaddr *)&icmpdst,
546 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
547 (struct sockaddr *)&icmpgw);
548 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
549 #ifdef IPSEC
550 key_sa_routechange((struct sockaddr *)&icmpsrc);
551 #endif
552 break;
553
554 /*
555 * No kernel processing for the following;
556 * just fall through to send to raw listener.
557 */
558 case ICMP_ECHOREPLY:
559 case ICMP_ROUTERADVERT:
560 case ICMP_ROUTERSOLICIT:
561 case ICMP_TSTAMPREPLY:
562 case ICMP_IREQREPLY:
563 case ICMP_MASKREPLY:
564 default:
565 break;
566 }
567
568 raw:
569 rip_input(m, off);
570 return;
571
572 freeit:
573 m_freem(m);
574 }
575
576 /*
577 * Reflect the ip packet back to the source
578 */
579 static void
580 icmp_reflect(m)
581 struct mbuf *m;
582 {
583 struct ip *ip = mtod(m, struct ip *);
584 struct ifaddr *ifa;
585 struct ifnet *ifn;
586 struct in_ifaddr *ia;
587 struct in_addr t;
588 struct mbuf *opts = 0;
589 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
590
591 if (!in_canforward(ip->ip_src) &&
592 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
593 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
594 m_freem(m); /* Bad return address */
595 icmpstat.icps_badaddr++;
596 goto done; /* Ip_output() will check for broadcast */
597 }
598 t = ip->ip_dst;
599 ip->ip_dst = ip->ip_src;
600
601 /*
602 * Source selection for ICMP replies:
603 *
604 * If the incoming packet was addressed directly to one of our
605 * own addresses, use dst as the src for the reply.
606 */
607 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
608 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
609 goto match;
610 /*
611 * If the incoming packet was addressed to one of our broadcast
612 * addresses, use the first non-broadcast address which corresponds
613 * to the incoming interface.
614 */
615 if (m->m_pkthdr.rcvif != NULL &&
616 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
617 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
618 if (ifa->ifa_addr->sa_family != AF_INET)
619 continue;
620 ia = ifatoia(ifa);
621 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
622 t.s_addr)
623 goto match;
624 }
625 }
626 /*
627 * If the incoming packet was not addressed directly to us, use
628 * designated interface for icmp replies specified by sysctl
629 * net.inet.icmp.reply_src (default not set). Otherwise continue
630 * with normal source selection.
631 */
632 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) {
633 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) {
634 if (ifa->ifa_addr->sa_family != AF_INET)
635 continue;
636 ia = ifatoia(ifa);
637 goto match;
638 }
639 }
640 /*
641 * If the packet was transiting through us, use the address of
642 * the interface that is the closest to the packet source.
643 * When we don't have a route back to the packet source, stop here
644 * and drop the packet.
645 */
646 ia = ip_rtaddr(ip->ip_dst);
647 if (ia == NULL) {
648 m_freem(m);
649 icmpstat.icps_noroute++;
650 goto done;
651 }
652 match:
653 #ifdef MAC
654 mac_reflect_mbuf_icmp(m);
655 #endif
656 t = IA_SIN(ia)->sin_addr;
657 ip->ip_src = t;
658 ip->ip_ttl = ip_defttl;
659
660 if (optlen > 0) {
661 register u_char *cp;
662 int opt, cnt;
663 u_int len;
664
665 /*
666 * Retrieve any source routing from the incoming packet;
667 * add on any record-route or timestamp options.
668 */
669 cp = (u_char *) (ip + 1);
670 if ((opts = ip_srcroute(m)) == 0 &&
671 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
672 opts->m_len = sizeof(struct in_addr);
673 mtod(opts, struct in_addr *)->s_addr = 0;
674 }
675 if (opts) {
676 #ifdef ICMPPRINTFS
677 if (icmpprintfs)
678 printf("icmp_reflect optlen %d rt %d => ",
679 optlen, opts->m_len);
680 #endif
681 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
682 opt = cp[IPOPT_OPTVAL];
683 if (opt == IPOPT_EOL)
684 break;
685 if (opt == IPOPT_NOP)
686 len = 1;
687 else {
688 if (cnt < IPOPT_OLEN + sizeof(*cp))
689 break;
690 len = cp[IPOPT_OLEN];
691 if (len < IPOPT_OLEN + sizeof(*cp) ||
692 len > cnt)
693 break;
694 }
695 /*
696 * Should check for overflow, but it "can't happen"
697 */
698 if (opt == IPOPT_RR || opt == IPOPT_TS ||
699 opt == IPOPT_SECURITY) {
700 bcopy((caddr_t)cp,
701 mtod(opts, caddr_t) + opts->m_len, len);
702 opts->m_len += len;
703 }
704 }
705 /* Terminate & pad, if necessary */
706 cnt = opts->m_len % 4;
707 if (cnt) {
708 for (; cnt < 4; cnt++) {
709 *(mtod(opts, caddr_t) + opts->m_len) =
710 IPOPT_EOL;
711 opts->m_len++;
712 }
713 }
714 #ifdef ICMPPRINTFS
715 if (icmpprintfs)
716 printf("%d\n", opts->m_len);
717 #endif
718 }
719 /*
720 * Now strip out original options by copying rest of first
721 * mbuf's data back, and adjust the IP length.
722 */
723 ip->ip_len -= optlen;
724 ip->ip_v = IPVERSION;
725 ip->ip_hl = 5;
726 m->m_len -= optlen;
727 if (m->m_flags & M_PKTHDR)
728 m->m_pkthdr.len -= optlen;
729 optlen += sizeof(struct ip);
730 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
731 (unsigned)(m->m_len - sizeof(struct ip)));
732 }
733 m_tag_delete_nonpersistent(m);
734 m->m_flags &= ~(M_BCAST|M_MCAST);
735 icmp_send(m, opts);
736 done:
737 if (opts)
738 (void)m_free(opts);
739 }
740
741 /*
742 * Send an icmp packet back to the ip level,
743 * after supplying a checksum.
744 */
745 static void
746 icmp_send(m, opts)
747 register struct mbuf *m;
748 struct mbuf *opts;
749 {
750 register struct ip *ip = mtod(m, struct ip *);
751 register int hlen;
752 register struct icmp *icp;
753
754 hlen = ip->ip_hl << 2;
755 m->m_data += hlen;
756 m->m_len -= hlen;
757 icp = mtod(m, struct icmp *);
758 icp->icmp_cksum = 0;
759 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
760 m->m_data -= hlen;
761 m->m_len += hlen;
762 m->m_pkthdr.rcvif = (struct ifnet *)0;
763 #ifdef ICMPPRINTFS
764 if (icmpprintfs) {
765 char buf[4 * sizeof "123"];
766 strcpy(buf, inet_ntoa(ip->ip_dst));
767 printf("icmp_send dst %s src %s\n",
768 buf, inet_ntoa(ip->ip_src));
769 }
770 #endif
771 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
772 }
773
774 n_time
775 iptime()
776 {
777 struct timeval atv;
778 u_long t;
779
780 getmicrotime(&atv);
781 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
782 return (htonl(t));
783 }
784
785 /*
786 * Return the next larger or smaller MTU plateau (table from RFC 1191)
787 * given current value MTU. If DIR is less than zero, a larger plateau
788 * is returned; otherwise, a smaller value is returned.
789 */
790 int
791 ip_next_mtu(mtu, dir)
792 int mtu;
793 int dir;
794 {
795 static int mtutab[] = {
796 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
797 296, 68, 0
798 };
799 int i;
800
801 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
802 if (mtu >= mtutab[i])
803 break;
804 }
805
806 if (dir < 0) {
807 if (i == 0) {
808 return 0;
809 } else {
810 return mtutab[i - 1];
811 }
812 } else {
813 if (mtutab[i] == 0) {
814 return 0;
815 } else if(mtu > mtutab[i]) {
816 return mtutab[i];
817 } else {
818 return mtutab[i + 1];
819 }
820 }
821 }
822
823
824 /*
825 * badport_bandlim() - check for ICMP bandwidth limit
826 *
827 * Return 0 if it is ok to send an ICMP error response, -1 if we have
828 * hit our bandwidth limit and it is not ok.
829 *
830 * If icmplim is <= 0, the feature is disabled and 0 is returned.
831 *
832 * For now we separate the TCP and UDP subsystems w/ different 'which'
833 * values. We may eventually remove this separation (and simplify the
834 * code further).
835 *
836 * Note that the printing of the error message is delayed so we can
837 * properly print the icmp error rate that the system was trying to do
838 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
839 * the 'final' error, but it doesn't make sense to solve the printing
840 * delay with more complex code.
841 */
842
843 int
844 badport_bandlim(int which)
845 {
846 #define N(a) (sizeof (a) / sizeof (a[0]))
847 static struct rate {
848 const char *type;
849 struct timeval lasttime;
850 int curpps;
851 } rates[BANDLIM_MAX+1] = {
852 { "icmp unreach response" },
853 { "icmp ping response" },
854 { "icmp tstamp response" },
855 { "closed port RST response" },
856 { "open port RST response" }
857 };
858
859 /*
860 * Return ok status if feature disabled or argument out of range.
861 */
862 if (icmplim > 0 && (u_int) which < N(rates)) {
863 struct rate *r = &rates[which];
864 int opps = r->curpps;
865
866 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim))
867 return -1; /* discard packet */
868 /*
869 * If we've dropped below the threshold after having
870 * rate-limited traffic print the message. This preserves
871 * the previous behaviour at the expense of added complexity.
872 */
873 if (icmplim_output && opps > icmplim)
874 printf("Limiting %s from %d to %d packets/sec\n",
875 r->type, opps, icmplim);
876 }
877 return 0; /* okay to send packet */
878 #undef N
879 }
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