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 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: releng/7.3/sys/netinet/ip_icmp.c 188587 2009-02-13 18:09:38Z luigi $");
34
35 #include "opt_ipsec.h"
36 #include "opt_mac.h"
37
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/mbuf.h>
41 #include <sys/protosw.h>
42 #include <sys/socket.h>
43 #include <sys/time.h>
44 #include <sys/kernel.h>
45 #include <sys/sysctl.h>
46
47 #include <net/if.h>
48 #include <net/if_types.h>
49 #include <net/route.h>
50
51 #include <netinet/in.h>
52 #include <netinet/in_pcb.h>
53 #include <netinet/in_systm.h>
54 #include <netinet/in_var.h>
55 #include <netinet/ip.h>
56 #include <netinet/ip_icmp.h>
57 #include <netinet/ip_var.h>
58 #include <netinet/ip_options.h>
59 #include <netinet/tcp.h>
60 #include <netinet/tcp_var.h>
61 #include <netinet/tcpip.h>
62 #include <netinet/icmp_var.h>
63
64 #ifdef IPSEC
65 #include <netipsec/ipsec.h>
66 #include <netipsec/key.h>
67 #endif
68
69 #include <machine/in_cksum.h>
70
71 #include <security/mac/mac_framework.h>
72
73 /*
74 * ICMP routines: error generation, receive packet processing, and
75 * routines to turnaround packets back to the originator, and
76 * host table maintenance routines.
77 */
78
79 struct icmpstat icmpstat;
80 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
81 &icmpstat, icmpstat, "");
82
83 static int icmpmaskrepl = 0;
84 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
85 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets.");
86
87 static u_int icmpmaskfake = 0;
88 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
89 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets.");
90
91 static int drop_redirect = 0;
92 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
93 &drop_redirect, 0, "Ignore ICMP redirects");
94
95 static int log_redirect = 0;
96 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
97 &log_redirect, 0, "Log ICMP redirects to the console");
98
99 static int icmplim = 200;
100 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
101 &icmplim, 0, "Maximum number of ICMP responses per second");
102
103 static int icmplim_output = 1;
104 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
105 &icmplim_output, 0, "Enable rate limiting of ICMP responses");
106
107 static char reply_src[IFNAMSIZ];
108 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
109 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets.");
110
111 static int icmp_rfi = 0;
112 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
113 &icmp_rfi, 0, "ICMP reply from incoming interface for "
114 "non-local packets");
115
116 static int icmp_quotelen = 8;
117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
118 &icmp_quotelen, 0, "Number of bytes from original packet to "
119 "quote in ICMP reply");
120
121 /*
122 * ICMP broadcast echo sysctl
123 */
124
125 static int icmpbmcastecho = 0;
126 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
127 &icmpbmcastecho, 0, "");
128
129
130 #ifdef ICMPPRINTFS
131 int icmpprintfs = 0;
132 #endif
133
134 static void icmp_reflect(struct mbuf *);
135 static void icmp_send(struct mbuf *, struct mbuf *);
136
137 extern struct protosw inetsw[];
138
139 /*
140 * Generate an error packet of type error
141 * in response to bad packet ip.
142 */
143 void
144 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
145 {
146 register struct ip *oip = mtod(n, struct ip *), *nip;
147 register unsigned oiphlen = oip->ip_hl << 2;
148 register struct icmp *icp;
149 register struct mbuf *m;
150 unsigned icmplen, icmpelen, nlen;
151
152 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
153 #ifdef ICMPPRINTFS
154 if (icmpprintfs)
155 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
156 #endif
157 if (type != ICMP_REDIRECT)
158 icmpstat.icps_error++;
159 /*
160 * Don't send error:
161 * if the original packet was encrypted.
162 * if not the first fragment of message.
163 * in response to a multicast or broadcast packet.
164 * if the old packet protocol was an ICMP error message.
165 */
166 if (n->m_flags & M_DECRYPTED)
167 goto freeit;
168 if (oip->ip_off & ~(IP_MF|IP_DF))
169 goto freeit;
170 if (n->m_flags & (M_BCAST|M_MCAST))
171 goto freeit;
172 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
173 n->m_len >= oiphlen + ICMP_MINLEN &&
174 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
175 icmpstat.icps_oldicmp++;
176 goto freeit;
177 }
178 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
179 if (oiphlen + 8 > n->m_len)
180 goto freeit;
181 /*
182 * Calculate length to quote from original packet and
183 * prevent the ICMP mbuf from overflowing.
184 * Unfortunatly this is non-trivial since ip_forward()
185 * sends us truncated packets.
186 */
187 nlen = m_length(n, NULL);
188 if (oip->ip_p == IPPROTO_TCP) {
189 struct tcphdr *th;
190 int tcphlen;
191
192 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
193 n->m_next == NULL)
194 goto stdreply;
195 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
196 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
197 goto freeit;
198 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
199 tcphlen = th->th_off << 2;
200 if (tcphlen < sizeof(struct tcphdr))
201 goto freeit;
202 if (oip->ip_len < oiphlen + tcphlen)
203 goto freeit;
204 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
205 goto stdreply;
206 if (n->m_len < oiphlen + tcphlen &&
207 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
208 goto freeit;
209 icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen));
210 } else
211 stdreply: icmpelen = max(8, min(icmp_quotelen, oip->ip_len - oiphlen));
212
213 icmplen = min(oiphlen + icmpelen, nlen);
214 if (icmplen < sizeof(struct ip))
215 goto freeit;
216
217 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
218 m = m_gethdr(M_DONTWAIT, MT_DATA);
219 else
220 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
221 if (m == NULL)
222 goto freeit;
223 #ifdef MAC
224 mac_create_mbuf_netlayer(n, m);
225 #endif
226 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
227 m_align(m, ICMP_MINLEN + icmplen);
228 m->m_len = ICMP_MINLEN + icmplen;
229
230 /* XXX MRT make the outgoing packet use the same FIB
231 * that was associated with the incoming packet
232 */
233 M_SETFIB(m, M_GETFIB(n));
234 icp = mtod(m, struct icmp *);
235 icmpstat.icps_outhist[type]++;
236 icp->icmp_type = type;
237 if (type == ICMP_REDIRECT)
238 icp->icmp_gwaddr.s_addr = dest;
239 else {
240 icp->icmp_void = 0;
241 /*
242 * The following assignments assume an overlay with the
243 * just zeroed icmp_void field.
244 */
245 if (type == ICMP_PARAMPROB) {
246 icp->icmp_pptr = code;
247 code = 0;
248 } else if (type == ICMP_UNREACH &&
249 code == ICMP_UNREACH_NEEDFRAG && mtu) {
250 icp->icmp_nextmtu = htons(mtu);
251 }
252 }
253 icp->icmp_code = code;
254
255 /*
256 * Copy the quotation into ICMP message and
257 * convert quoted IP header back to network representation.
258 */
259 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
260 nip = &icp->icmp_ip;
261 nip->ip_len = htons(nip->ip_len);
262 nip->ip_off = htons(nip->ip_off);
263
264 /*
265 * Set up ICMP message mbuf and copy old IP header (without options
266 * in front of ICMP message.
267 * If the original mbuf was meant to bypass the firewall, the error
268 * reply should bypass as well.
269 */
270 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
271 m->m_data -= sizeof(struct ip);
272 m->m_len += sizeof(struct ip);
273 m->m_pkthdr.len = m->m_len;
274 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
275 nip = mtod(m, struct ip *);
276 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
277 nip->ip_len = m->m_len;
278 nip->ip_v = IPVERSION;
279 nip->ip_hl = 5;
280 nip->ip_p = IPPROTO_ICMP;
281 nip->ip_tos = 0;
282 icmp_reflect(m);
283
284 freeit:
285 m_freem(n);
286 }
287
288 /*
289 * Process a received ICMP message.
290 */
291 void
292 icmp_input(struct mbuf *m, int off)
293 {
294 struct icmp *icp;
295 struct in_ifaddr *ia;
296 struct ip *ip = mtod(m, struct ip *);
297 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
298 int hlen = off;
299 int icmplen = ip->ip_len;
300 int i, code;
301 void (*ctlfunc)(int, struct sockaddr *, void *);
302 int fibnum;
303
304 /*
305 * Locate icmp structure in mbuf, and check
306 * that not corrupted and of at least minimum length.
307 */
308 #ifdef ICMPPRINTFS
309 if (icmpprintfs) {
310 char buf[4 * sizeof "123"];
311 strcpy(buf, inet_ntoa(ip->ip_src));
312 printf("icmp_input from %s to %s, len %d\n",
313 buf, inet_ntoa(ip->ip_dst), icmplen);
314 }
315 #endif
316 if (icmplen < ICMP_MINLEN) {
317 icmpstat.icps_tooshort++;
318 goto freeit;
319 }
320 i = hlen + min(icmplen, ICMP_ADVLENMIN);
321 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
322 icmpstat.icps_tooshort++;
323 return;
324 }
325 ip = mtod(m, struct ip *);
326 m->m_len -= hlen;
327 m->m_data += hlen;
328 icp = mtod(m, struct icmp *);
329 if (in_cksum(m, icmplen)) {
330 icmpstat.icps_checksum++;
331 goto freeit;
332 }
333 m->m_len += hlen;
334 m->m_data -= hlen;
335
336 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
337 /*
338 * Deliver very specific ICMP type only.
339 */
340 switch (icp->icmp_type) {
341 case ICMP_UNREACH:
342 case ICMP_TIMXCEED:
343 break;
344 default:
345 goto freeit;
346 }
347 }
348
349 #ifdef ICMPPRINTFS
350 if (icmpprintfs)
351 printf("icmp_input, type %d code %d\n", icp->icmp_type,
352 icp->icmp_code);
353 #endif
354
355 /*
356 * Message type specific processing.
357 */
358 if (icp->icmp_type > ICMP_MAXTYPE)
359 goto raw;
360
361 /* Initialize */
362 bzero(&icmpsrc, sizeof(icmpsrc));
363 icmpsrc.sin_len = sizeof(struct sockaddr_in);
364 icmpsrc.sin_family = AF_INET;
365 bzero(&icmpdst, sizeof(icmpdst));
366 icmpdst.sin_len = sizeof(struct sockaddr_in);
367 icmpdst.sin_family = AF_INET;
368 bzero(&icmpgw, sizeof(icmpgw));
369 icmpgw.sin_len = sizeof(struct sockaddr_in);
370 icmpgw.sin_family = AF_INET;
371
372 icmpstat.icps_inhist[icp->icmp_type]++;
373 code = icp->icmp_code;
374 switch (icp->icmp_type) {
375
376 case ICMP_UNREACH:
377 switch (code) {
378 case ICMP_UNREACH_NET:
379 case ICMP_UNREACH_HOST:
380 case ICMP_UNREACH_SRCFAIL:
381 case ICMP_UNREACH_NET_UNKNOWN:
382 case ICMP_UNREACH_HOST_UNKNOWN:
383 case ICMP_UNREACH_ISOLATED:
384 case ICMP_UNREACH_TOSNET:
385 case ICMP_UNREACH_TOSHOST:
386 case ICMP_UNREACH_HOST_PRECEDENCE:
387 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
388 code = PRC_UNREACH_NET;
389 break;
390
391 case ICMP_UNREACH_NEEDFRAG:
392 code = PRC_MSGSIZE;
393 break;
394
395 /*
396 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
397 * Treat subcodes 2,3 as immediate RST
398 */
399 case ICMP_UNREACH_PROTOCOL:
400 case ICMP_UNREACH_PORT:
401 code = PRC_UNREACH_PORT;
402 break;
403
404 case ICMP_UNREACH_NET_PROHIB:
405 case ICMP_UNREACH_HOST_PROHIB:
406 case ICMP_UNREACH_FILTER_PROHIB:
407 code = PRC_UNREACH_ADMIN_PROHIB;
408 break;
409
410 default:
411 goto badcode;
412 }
413 goto deliver;
414
415 case ICMP_TIMXCEED:
416 if (code > 1)
417 goto badcode;
418 code += PRC_TIMXCEED_INTRANS;
419 goto deliver;
420
421 case ICMP_PARAMPROB:
422 if (code > 1)
423 goto badcode;
424 code = PRC_PARAMPROB;
425 goto deliver;
426
427 case ICMP_SOURCEQUENCH:
428 if (code)
429 goto badcode;
430 code = PRC_QUENCH;
431 deliver:
432 /*
433 * Problem with datagram; advise higher level routines.
434 */
435 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
436 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
437 icmpstat.icps_badlen++;
438 goto freeit;
439 }
440 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
441 /* Discard ICMP's in response to multicast packets */
442 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
443 goto badcode;
444 #ifdef ICMPPRINTFS
445 if (icmpprintfs)
446 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
447 #endif
448 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
449 /*
450 * XXX if the packet contains [IPv4 AH TCP], we can't make a
451 * notification to TCP layer.
452 */
453 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
454 if (ctlfunc)
455 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
456 (void *)&icp->icmp_ip);
457 break;
458
459 badcode:
460 icmpstat.icps_badcode++;
461 break;
462
463 case ICMP_ECHO:
464 if (!icmpbmcastecho
465 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
466 icmpstat.icps_bmcastecho++;
467 break;
468 }
469 icp->icmp_type = ICMP_ECHOREPLY;
470 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
471 goto freeit;
472 else
473 goto reflect;
474
475 case ICMP_TSTAMP:
476 if (!icmpbmcastecho
477 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
478 icmpstat.icps_bmcasttstamp++;
479 break;
480 }
481 if (icmplen < ICMP_TSLEN) {
482 icmpstat.icps_badlen++;
483 break;
484 }
485 icp->icmp_type = ICMP_TSTAMPREPLY;
486 icp->icmp_rtime = iptime();
487 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
488 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
489 goto freeit;
490 else
491 goto reflect;
492
493 case ICMP_MASKREQ:
494 if (icmpmaskrepl == 0)
495 break;
496 /*
497 * We are not able to respond with all ones broadcast
498 * unless we receive it over a point-to-point interface.
499 */
500 if (icmplen < ICMP_MASKLEN)
501 break;
502 switch (ip->ip_dst.s_addr) {
503
504 case INADDR_BROADCAST:
505 case INADDR_ANY:
506 icmpdst.sin_addr = ip->ip_src;
507 break;
508
509 default:
510 icmpdst.sin_addr = ip->ip_dst;
511 }
512 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
513 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
514 if (ia == 0)
515 break;
516 if (ia->ia_ifp == 0)
517 break;
518 icp->icmp_type = ICMP_MASKREPLY;
519 if (icmpmaskfake == 0)
520 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
521 else
522 icp->icmp_mask = icmpmaskfake;
523 if (ip->ip_src.s_addr == 0) {
524 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
525 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
526 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
527 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
528 }
529 reflect:
530 ip->ip_len += hlen; /* since ip_input deducts this */
531 icmpstat.icps_reflect++;
532 icmpstat.icps_outhist[icp->icmp_type]++;
533 icmp_reflect(m);
534 return;
535
536 case ICMP_REDIRECT:
537 if (log_redirect) {
538 u_long src, dst, gw;
539
540 src = ntohl(ip->ip_src.s_addr);
541 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
542 gw = ntohl(icp->icmp_gwaddr.s_addr);
543 printf("icmp redirect from %d.%d.%d.%d: "
544 "%d.%d.%d.%d => %d.%d.%d.%d\n",
545 (int)(src >> 24), (int)((src >> 16) & 0xff),
546 (int)((src >> 8) & 0xff), (int)(src & 0xff),
547 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
548 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
549 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
550 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
551 }
552 /*
553 * RFC1812 says we must ignore ICMP redirects if we
554 * are acting as router.
555 */
556 if (drop_redirect || ipforwarding)
557 break;
558 if (code > 3)
559 goto badcode;
560 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
561 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
562 icmpstat.icps_badlen++;
563 break;
564 }
565 /*
566 * Short circuit routing redirects to force
567 * immediate change in the kernel's routing
568 * tables. The message is also handed to anyone
569 * listening on a raw socket (e.g. the routing
570 * daemon for use in updating its tables).
571 */
572 icmpgw.sin_addr = ip->ip_src;
573 icmpdst.sin_addr = icp->icmp_gwaddr;
574 #ifdef ICMPPRINTFS
575 if (icmpprintfs) {
576 char buf[4 * sizeof "123"];
577 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
578
579 printf("redirect dst %s to %s\n",
580 buf, inet_ntoa(icp->icmp_gwaddr));
581 }
582 #endif
583 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
584 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
585 in_rtredirect((struct sockaddr *)&icmpsrc,
586 (struct sockaddr *)&icmpdst,
587 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
588 (struct sockaddr *)&icmpgw, fibnum);
589 }
590 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
591 #ifdef IPSEC
592 key_sa_routechange((struct sockaddr *)&icmpsrc);
593 #endif
594 break;
595
596 /*
597 * No kernel processing for the following;
598 * just fall through to send to raw listener.
599 */
600 case ICMP_ECHOREPLY:
601 case ICMP_ROUTERADVERT:
602 case ICMP_ROUTERSOLICIT:
603 case ICMP_TSTAMPREPLY:
604 case ICMP_IREQREPLY:
605 case ICMP_MASKREPLY:
606 default:
607 break;
608 }
609
610 raw:
611 rip_input(m, off);
612 return;
613
614 freeit:
615 m_freem(m);
616 }
617
618 /*
619 * Reflect the ip packet back to the source
620 */
621 static void
622 icmp_reflect(struct mbuf *m)
623 {
624 struct ip *ip = mtod(m, struct ip *);
625 struct ifaddr *ifa;
626 struct ifnet *ifn;
627 struct in_ifaddr *ia;
628 struct in_addr t;
629 struct mbuf *opts = 0;
630 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
631
632 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
633 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
634 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
635 m_freem(m); /* Bad return address */
636 icmpstat.icps_badaddr++;
637 goto done; /* Ip_output() will check for broadcast */
638 }
639
640 t = ip->ip_dst;
641 ip->ip_dst = ip->ip_src;
642
643 /*
644 * Source selection for ICMP replies:
645 *
646 * If the incoming packet was addressed directly to one of our
647 * own addresses, use dst as the src for the reply.
648 */
649 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
650 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
651 goto match;
652 /*
653 * If the incoming packet was addressed to one of our broadcast
654 * addresses, use the first non-broadcast address which corresponds
655 * to the incoming interface.
656 */
657 if (m->m_pkthdr.rcvif != NULL &&
658 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
659 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
660 if (ifa->ifa_addr->sa_family != AF_INET)
661 continue;
662 ia = ifatoia(ifa);
663 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
664 t.s_addr)
665 goto match;
666 }
667 }
668 /*
669 * If the packet was transiting through us, use the address of
670 * the interface the packet came through in. If that interface
671 * doesn't have a suitable IP address, the normal selection
672 * criteria apply.
673 */
674 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) {
675 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
676 if (ifa->ifa_addr->sa_family != AF_INET)
677 continue;
678 ia = ifatoia(ifa);
679 goto match;
680 }
681 }
682 /*
683 * If the incoming packet was not addressed directly to us, use
684 * designated interface for icmp replies specified by sysctl
685 * net.inet.icmp.reply_src (default not set). Otherwise continue
686 * with normal source selection.
687 */
688 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) {
689 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) {
690 if (ifa->ifa_addr->sa_family != AF_INET)
691 continue;
692 ia = ifatoia(ifa);
693 goto match;
694 }
695 }
696 /*
697 * If the packet was transiting through us, use the address of
698 * the interface that is the closest to the packet source.
699 * When we don't have a route back to the packet source, stop here
700 * and drop the packet.
701 */
702 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
703 if (ia == NULL) {
704 m_freem(m);
705 icmpstat.icps_noroute++;
706 goto done;
707 }
708 match:
709 #ifdef MAC
710 mac_reflect_mbuf_icmp(m);
711 #endif
712 t = IA_SIN(ia)->sin_addr;
713 ip->ip_src = t;
714 ip->ip_ttl = ip_defttl;
715
716 if (optlen > 0) {
717 register u_char *cp;
718 int opt, cnt;
719 u_int len;
720
721 /*
722 * Retrieve any source routing from the incoming packet;
723 * add on any record-route or timestamp options.
724 */
725 cp = (u_char *) (ip + 1);
726 if ((opts = ip_srcroute(m)) == 0 &&
727 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
728 opts->m_len = sizeof(struct in_addr);
729 mtod(opts, struct in_addr *)->s_addr = 0;
730 }
731 if (opts) {
732 #ifdef ICMPPRINTFS
733 if (icmpprintfs)
734 printf("icmp_reflect optlen %d rt %d => ",
735 optlen, opts->m_len);
736 #endif
737 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
738 opt = cp[IPOPT_OPTVAL];
739 if (opt == IPOPT_EOL)
740 break;
741 if (opt == IPOPT_NOP)
742 len = 1;
743 else {
744 if (cnt < IPOPT_OLEN + sizeof(*cp))
745 break;
746 len = cp[IPOPT_OLEN];
747 if (len < IPOPT_OLEN + sizeof(*cp) ||
748 len > cnt)
749 break;
750 }
751 /*
752 * Should check for overflow, but it "can't happen"
753 */
754 if (opt == IPOPT_RR || opt == IPOPT_TS ||
755 opt == IPOPT_SECURITY) {
756 bcopy((caddr_t)cp,
757 mtod(opts, caddr_t) + opts->m_len, len);
758 opts->m_len += len;
759 }
760 }
761 /* Terminate & pad, if necessary */
762 cnt = opts->m_len % 4;
763 if (cnt) {
764 for (; cnt < 4; cnt++) {
765 *(mtod(opts, caddr_t) + opts->m_len) =
766 IPOPT_EOL;
767 opts->m_len++;
768 }
769 }
770 #ifdef ICMPPRINTFS
771 if (icmpprintfs)
772 printf("%d\n", opts->m_len);
773 #endif
774 }
775 /*
776 * Now strip out original options by copying rest of first
777 * mbuf's data back, and adjust the IP length.
778 */
779 ip->ip_len -= optlen;
780 ip->ip_v = IPVERSION;
781 ip->ip_hl = 5;
782 m->m_len -= optlen;
783 if (m->m_flags & M_PKTHDR)
784 m->m_pkthdr.len -= optlen;
785 optlen += sizeof(struct ip);
786 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
787 (unsigned)(m->m_len - sizeof(struct ip)));
788 }
789 m_tag_delete_nonpersistent(m);
790 m->m_flags &= ~(M_BCAST|M_MCAST);
791 icmp_send(m, opts);
792 done:
793 if (opts)
794 (void)m_free(opts);
795 }
796
797 /*
798 * Send an icmp packet back to the ip level,
799 * after supplying a checksum.
800 */
801 static void
802 icmp_send(struct mbuf *m, struct mbuf *opts)
803 {
804 register struct ip *ip = mtod(m, struct ip *);
805 register int hlen;
806 register struct icmp *icp;
807
808 hlen = ip->ip_hl << 2;
809 m->m_data += hlen;
810 m->m_len -= hlen;
811 icp = mtod(m, struct icmp *);
812 icp->icmp_cksum = 0;
813 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
814 m->m_data -= hlen;
815 m->m_len += hlen;
816 m->m_pkthdr.rcvif = (struct ifnet *)0;
817 #ifdef ICMPPRINTFS
818 if (icmpprintfs) {
819 char buf[4 * sizeof "123"];
820 strcpy(buf, inet_ntoa(ip->ip_dst));
821 printf("icmp_send dst %s src %s\n",
822 buf, inet_ntoa(ip->ip_src));
823 }
824 #endif
825 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
826 }
827
828 /*
829 * Return milliseconds since 00:00 GMT in network format.
830 */
831 uint32_t
832 iptime(void)
833 {
834 struct timeval atv;
835 u_long t;
836
837 getmicrotime(&atv);
838 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
839 return (htonl(t));
840 }
841
842 /*
843 * Return the next larger or smaller MTU plateau (table from RFC 1191)
844 * given current value MTU. If DIR is less than zero, a larger plateau
845 * is returned; otherwise, a smaller value is returned.
846 */
847 int
848 ip_next_mtu(int mtu, int dir)
849 {
850 static int mtutab[] = {
851 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
852 296, 68, 0
853 };
854 int i, size;
855
856 size = (sizeof mtutab) / (sizeof mtutab[0]);
857 if (dir >= 0) {
858 for (i = 0; i < size; i++)
859 if (mtu > mtutab[i])
860 return mtutab[i];
861 } else {
862 for (i = size - 1; i >= 0; i--)
863 if (mtu < mtutab[i])
864 return mtutab[i];
865 if (mtu == mtutab[0])
866 return mtutab[0];
867 }
868 return 0;
869 }
870
871
872 /*
873 * badport_bandlim() - check for ICMP bandwidth limit
874 *
875 * Return 0 if it is ok to send an ICMP error response, -1 if we have
876 * hit our bandwidth limit and it is not ok.
877 *
878 * If icmplim is <= 0, the feature is disabled and 0 is returned.
879 *
880 * For now we separate the TCP and UDP subsystems w/ different 'which'
881 * values. We may eventually remove this separation (and simplify the
882 * code further).
883 *
884 * Note that the printing of the error message is delayed so we can
885 * properly print the icmp error rate that the system was trying to do
886 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
887 * the 'final' error, but it doesn't make sense to solve the printing
888 * delay with more complex code.
889 */
890
891 int
892 badport_bandlim(int which)
893 {
894 #define N(a) (sizeof (a) / sizeof (a[0]))
895 static struct rate {
896 const char *type;
897 struct timeval lasttime;
898 int curpps;
899 } rates[BANDLIM_MAX+1] = {
900 { "icmp unreach response" },
901 { "icmp ping response" },
902 { "icmp tstamp response" },
903 { "closed port RST response" },
904 { "open port RST response" },
905 { "icmp6 unreach response" }
906 };
907
908 /*
909 * Return ok status if feature disabled or argument out of range.
910 */
911 if (icmplim > 0 && (u_int) which < N(rates)) {
912 struct rate *r = &rates[which];
913 int opps = r->curpps;
914
915 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim))
916 return -1; /* discard packet */
917 /*
918 * If we've dropped below the threshold after having
919 * rate-limited traffic print the message. This preserves
920 * the previous behaviour at the expense of added complexity.
921 */
922 if (icmplim_output && opps > icmplim)
923 printf("Limiting %s from %d to %d packets/sec\n",
924 r->type, opps, icmplim);
925 }
926 return 0; /* okay to send packet */
927 #undef N
928 }
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