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: head/sys/netinet/ip_icmp.c 237230 2012-06-18 17:11:24Z tuexen $");
34
35#include "opt_inet.h"
36#include "opt_ipsec.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#include <sys/syslog.h>
47
48#include <net/if.h>
49#include <net/if_types.h>
50#include <net/route.h>
51#include <net/vnet.h>
52
53#include <netinet/in.h>
54#include <netinet/in_pcb.h>
55#include <netinet/in_systm.h>
56#include <netinet/in_var.h>
57#include <netinet/ip.h>
58#include <netinet/ip_icmp.h>
59#include <netinet/ip_var.h>
60#include <netinet/ip_options.h>
61#include <netinet/tcp.h>
62#include <netinet/tcp_var.h>
63#include <netinet/tcpip.h>
64#include <netinet/icmp_var.h>
65
66#ifdef INET
67#ifdef IPSEC
68#include <netipsec/ipsec.h>
69#include <netipsec/key.h>
70#endif
71
72#include <machine/in_cksum.h>
73
74#include <security/mac/mac_framework.h>
75#endif /* INET */
76
77/*
78 * ICMP routines: error generation, receive packet processing, and
79 * routines to turnaround packets back to the originator, and
80 * host table maintenance routines.
81 */
82static VNET_DEFINE(int, icmplim) = 200;
83#define V_icmplim VNET(icmplim)
84SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
85 &VNET_NAME(icmplim), 0,
86 "Maximum number of ICMP responses per second");
87
88static VNET_DEFINE(int, icmplim_output) = 1;
89#define V_icmplim_output VNET(icmplim_output)
90SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
91 &VNET_NAME(icmplim_output), 0,
92 "Enable logging of ICMP response rate limiting");
93
94#ifdef INET
95VNET_DEFINE(struct icmpstat, icmpstat);
96SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
97 &VNET_NAME(icmpstat), icmpstat, "");
98
99static VNET_DEFINE(int, icmpmaskrepl) = 0;
100#define V_icmpmaskrepl VNET(icmpmaskrepl)
101SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
102 &VNET_NAME(icmpmaskrepl), 0,
103 "Reply to ICMP Address Mask Request packets.");
104
105static VNET_DEFINE(u_int, icmpmaskfake) = 0;
106#define V_icmpmaskfake VNET(icmpmaskfake)
107SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
108 &VNET_NAME(icmpmaskfake), 0,
109 "Fake reply to ICMP Address Mask Request packets.");
110
111static VNET_DEFINE(int, drop_redirect) = 0;
112#define V_drop_redirect VNET(drop_redirect)
113SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
114 &VNET_NAME(drop_redirect), 0,
115 "Ignore ICMP redirects");
116
117static VNET_DEFINE(int, log_redirect) = 0;
118#define V_log_redirect VNET(log_redirect)
119SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
120 &VNET_NAME(log_redirect), 0,
121 "Log ICMP redirects to the console");
122
123static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
124#define V_reply_src VNET(reply_src)
125SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
126 &VNET_NAME(reply_src), IFNAMSIZ,
127 "icmp reply source for non-local packets.");
128
129static VNET_DEFINE(int, icmp_rfi) = 0;
130#define V_icmp_rfi VNET(icmp_rfi)
131SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
132 &VNET_NAME(icmp_rfi), 0,
133 "ICMP reply from incoming interface for non-local packets");
134
135static VNET_DEFINE(int, icmp_quotelen) = 8;
136#define V_icmp_quotelen VNET(icmp_quotelen)
137SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
138 &VNET_NAME(icmp_quotelen), 0,
139 "Number of bytes from original packet to quote in ICMP reply");
140
141/*
142 * ICMP broadcast echo sysctl
143 */
144static VNET_DEFINE(int, icmpbmcastecho) = 0;
145#define V_icmpbmcastecho VNET(icmpbmcastecho)
146SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
147 &VNET_NAME(icmpbmcastecho), 0,
148 "");
149
150
151#ifdef ICMPPRINTFS
152int icmpprintfs = 0;
153#endif
154
155static void icmp_reflect(struct mbuf *);
156static void icmp_send(struct mbuf *, struct mbuf *);
157
158extern struct protosw inetsw[];
159
160/*
161 * Kernel module interface for updating icmpstat. The argument is an index
162 * into icmpstat treated as an array of u_long. While this encodes the
163 * general layout of icmpstat into the caller, it doesn't encode its
164 * location, so that future changes to add, for example, per-CPU stats
165 * support won't cause binary compatibility problems for kernel modules.
166 */
167void
168kmod_icmpstat_inc(int statnum)
169{
170
171 (*((u_long *)&V_icmpstat + statnum))++;
172}
173
174/*
175 * Generate an error packet of type error
176 * in response to bad packet ip.
177 */
178void
179icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
180{
181 register struct ip *oip = mtod(n, struct ip *), *nip;
182 register unsigned oiphlen = oip->ip_hl << 2;
183 register struct icmp *icp;
184 register struct mbuf *m;
185 unsigned icmplen, icmpelen, nlen;
186
187 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
188#ifdef ICMPPRINTFS
189 if (icmpprintfs)
190 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
191#endif
192 if (type != ICMP_REDIRECT)
193 ICMPSTAT_INC(icps_error);
194 /*
195 * Don't send error:
196 * if the original packet was encrypted.
197 * if not the first fragment of message.
198 * in response to a multicast or broadcast packet.
199 * if the old packet protocol was an ICMP error message.
200 */
201 if (n->m_flags & M_DECRYPTED)
202 goto freeit;
203 if (oip->ip_off & ~(IP_MF|IP_DF))
204 goto freeit;
205 if (n->m_flags & (M_BCAST|M_MCAST))
206 goto freeit;
207 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
208 n->m_len >= oiphlen + ICMP_MINLEN &&
209 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
210 ICMPSTAT_INC(icps_oldicmp);
211 goto freeit;
212 }
213 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
214 if (oiphlen + 8 > n->m_len)
215 goto freeit;
216 /*
217 * Calculate length to quote from original packet and
218 * prevent the ICMP mbuf from overflowing.
219 * Unfortunatly this is non-trivial since ip_forward()
220 * sends us truncated packets.
221 */
222 nlen = m_length(n, NULL);
223 if (oip->ip_p == IPPROTO_TCP) {
224 struct tcphdr *th;
225 int tcphlen;
226
227 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
228 n->m_next == NULL)
229 goto stdreply;
230 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
231 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
232 goto freeit;
233 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
234 tcphlen = th->th_off << 2;
235 if (tcphlen < sizeof(struct tcphdr))
236 goto freeit;
237 if (oip->ip_len < oiphlen + tcphlen)
238 goto freeit;
239 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
240 goto stdreply;
241 if (n->m_len < oiphlen + tcphlen &&
242 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
243 goto freeit;
244 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen));
245 } else
246stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen));
247
248 icmplen = min(oiphlen + icmpelen, nlen);
249 if (icmplen < sizeof(struct ip))
250 goto freeit;
251
252 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
253 m = m_gethdr(M_DONTWAIT, MT_DATA);
254 else
255 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
256 if (m == NULL)
257 goto freeit;
258#ifdef MAC
259 mac_netinet_icmp_reply(n, m);
260#endif
261 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
262 m_align(m, ICMP_MINLEN + icmplen);
263 m->m_len = ICMP_MINLEN + icmplen;
264
265 /* XXX MRT make the outgoing packet use the same FIB
266 * that was associated with the incoming packet
267 */
268 M_SETFIB(m, M_GETFIB(n));
269 icp = mtod(m, struct icmp *);
270 ICMPSTAT_INC(icps_outhist[type]);
271 icp->icmp_type = type;
272 if (type == ICMP_REDIRECT)
273 icp->icmp_gwaddr.s_addr = dest;
274 else {
275 icp->icmp_void = 0;
276 /*
277 * The following assignments assume an overlay with the
278 * just zeroed icmp_void field.
279 */
280 if (type == ICMP_PARAMPROB) {
281 icp->icmp_pptr = code;
282 code = 0;
283 } else if (type == ICMP_UNREACH &&
284 code == ICMP_UNREACH_NEEDFRAG && mtu) {
285 icp->icmp_nextmtu = htons(mtu);
286 }
287 }
288 icp->icmp_code = code;
289
290 /*
291 * Copy the quotation into ICMP message and
292 * convert quoted IP header back to network representation.
293 */
294 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
295 nip = &icp->icmp_ip;
296 nip->ip_len = htons(nip->ip_len);
297 nip->ip_off = htons(nip->ip_off);
298
299 /*
300 * Set up ICMP message mbuf and copy old IP header (without options
301 * in front of ICMP message.
302 * If the original mbuf was meant to bypass the firewall, the error
303 * reply should bypass as well.
304 */
305 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
306 m->m_data -= sizeof(struct ip);
307 m->m_len += sizeof(struct ip);
308 m->m_pkthdr.len = m->m_len;
309 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
310 nip = mtod(m, struct ip *);
311 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
312 nip->ip_len = m->m_len;
313 nip->ip_v = IPVERSION;
314 nip->ip_hl = 5;
315 nip->ip_p = IPPROTO_ICMP;
316 nip->ip_tos = 0;
317 icmp_reflect(m);
318
319freeit:
320 m_freem(n);
321}
322
323/*
324 * Process a received ICMP message.
325 */
326void
327icmp_input(struct mbuf *m, int off)
328{
329 struct icmp *icp;
330 struct in_ifaddr *ia;
331 struct ip *ip = mtod(m, struct ip *);
332 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
333 int hlen = off;
334 int icmplen = ip->ip_len;
335 int i, code;
336 void (*ctlfunc)(int, struct sockaddr *, void *);
337 int fibnum;
338
339 /*
340 * Locate icmp structure in mbuf, and check
341 * that not corrupted and of at least minimum length.
342 */
343#ifdef ICMPPRINTFS
344 if (icmpprintfs) {
345 char buf[4 * sizeof "123"];
346 strcpy(buf, inet_ntoa(ip->ip_src));
347 printf("icmp_input from %s to %s, len %d\n",
348 buf, inet_ntoa(ip->ip_dst), icmplen);
349 }
350#endif
351 if (icmplen < ICMP_MINLEN) {
352 ICMPSTAT_INC(icps_tooshort);
353 goto freeit;
354 }
355 i = hlen + min(icmplen, ICMP_ADVLENMIN);
356 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
357 ICMPSTAT_INC(icps_tooshort);
358 return;
359 }
360 ip = mtod(m, struct ip *);
361 m->m_len -= hlen;
362 m->m_data += hlen;
363 icp = mtod(m, struct icmp *);
364 if (in_cksum(m, icmplen)) {
365 ICMPSTAT_INC(icps_checksum);
366 goto freeit;
367 }
368 m->m_len += hlen;
369 m->m_data -= hlen;
370
371 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
372 /*
373 * Deliver very specific ICMP type only.
374 */
375 switch (icp->icmp_type) {
376 case ICMP_UNREACH:
377 case ICMP_TIMXCEED:
378 break;
379 default:
380 goto freeit;
381 }
382 }
383
384#ifdef ICMPPRINTFS
385 if (icmpprintfs)
386 printf("icmp_input, type %d code %d\n", icp->icmp_type,
387 icp->icmp_code);
388#endif
389
390 /*
391 * Message type specific processing.
392 */
393 if (icp->icmp_type > ICMP_MAXTYPE)
394 goto raw;
395
396 /* Initialize */
397 bzero(&icmpsrc, sizeof(icmpsrc));
398 icmpsrc.sin_len = sizeof(struct sockaddr_in);
399 icmpsrc.sin_family = AF_INET;
400 bzero(&icmpdst, sizeof(icmpdst));
401 icmpdst.sin_len = sizeof(struct sockaddr_in);
402 icmpdst.sin_family = AF_INET;
403 bzero(&icmpgw, sizeof(icmpgw));
404 icmpgw.sin_len = sizeof(struct sockaddr_in);
405 icmpgw.sin_family = AF_INET;
406
407 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
408 code = icp->icmp_code;
409 switch (icp->icmp_type) {
410
411 case ICMP_UNREACH:
412 switch (code) {
413 case ICMP_UNREACH_NET:
414 case ICMP_UNREACH_HOST:
415 case ICMP_UNREACH_SRCFAIL:
416 case ICMP_UNREACH_NET_UNKNOWN:
417 case ICMP_UNREACH_HOST_UNKNOWN:
418 case ICMP_UNREACH_ISOLATED:
419 case ICMP_UNREACH_TOSNET:
420 case ICMP_UNREACH_TOSHOST:
421 case ICMP_UNREACH_HOST_PRECEDENCE:
422 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
423 code = PRC_UNREACH_NET;
424 break;
425
426 case ICMP_UNREACH_NEEDFRAG:
427 code = PRC_MSGSIZE;
428 break;
429
430 /*
431 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
432 * Treat subcodes 2,3 as immediate RST
433 */
434 case ICMP_UNREACH_PROTOCOL:
435 case ICMP_UNREACH_PORT:
436 code = PRC_UNREACH_PORT;
437 break;
438
439 case ICMP_UNREACH_NET_PROHIB:
440 case ICMP_UNREACH_HOST_PROHIB:
441 case ICMP_UNREACH_FILTER_PROHIB:
442 code = PRC_UNREACH_ADMIN_PROHIB;
443 break;
444
445 default:
446 goto badcode;
447 }
448 goto deliver;
449
450 case ICMP_TIMXCEED:
451 if (code > 1)
452 goto badcode;
453 code += PRC_TIMXCEED_INTRANS;
454 goto deliver;
455
456 case ICMP_PARAMPROB:
457 if (code > 1)
458 goto badcode;
459 code = PRC_PARAMPROB;
460 goto deliver;
461
462 case ICMP_SOURCEQUENCH:
463 if (code)
464 goto badcode;
465 code = PRC_QUENCH;
466 deliver:
467 /*
468 * Problem with datagram; advise higher level routines.
469 */
470 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
471 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
472 ICMPSTAT_INC(icps_badlen);
473 goto freeit;
474 }
475 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
476 /* Discard ICMP's in response to multicast packets */
477 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
478 goto badcode;
479#ifdef ICMPPRINTFS
480 if (icmpprintfs)
481 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
482#endif
483 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
484 /*
485 * XXX if the packet contains [IPv4 AH TCP], we can't make a
486 * notification to TCP layer.
487 */
488 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
489 if (ctlfunc)
490 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
491 (void *)&icp->icmp_ip);
492 break;
493
494 badcode:
495 ICMPSTAT_INC(icps_badcode);
496 break;
497
498 case ICMP_ECHO:
499 if (!V_icmpbmcastecho
500 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
501 ICMPSTAT_INC(icps_bmcastecho);
502 break;
503 }
504 icp->icmp_type = ICMP_ECHOREPLY;
505 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
506 goto freeit;
507 else
508 goto reflect;
509
510 case ICMP_TSTAMP:
511 if (!V_icmpbmcastecho
512 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
513 ICMPSTAT_INC(icps_bmcasttstamp);
514 break;
515 }
516 if (icmplen < ICMP_TSLEN) {
517 ICMPSTAT_INC(icps_badlen);
518 break;
519 }
520 icp->icmp_type = ICMP_TSTAMPREPLY;
521 icp->icmp_rtime = iptime();
522 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
523 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
524 goto freeit;
525 else
526 goto reflect;
527
528 case ICMP_MASKREQ:
529 if (V_icmpmaskrepl == 0)
530 break;
531 /*
532 * We are not able to respond with all ones broadcast
533 * unless we receive it over a point-to-point interface.
534 */
535 if (icmplen < ICMP_MASKLEN)
536 break;
537 switch (ip->ip_dst.s_addr) {
538
539 case INADDR_BROADCAST:
540 case INADDR_ANY:
541 icmpdst.sin_addr = ip->ip_src;
542 break;
543
544 default:
545 icmpdst.sin_addr = ip->ip_dst;
546 }
547 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
548 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
549 if (ia == NULL)
550 break;
551 if (ia->ia_ifp == NULL) {
552 ifa_free(&ia->ia_ifa);
553 break;
554 }
555 icp->icmp_type = ICMP_MASKREPLY;
556 if (V_icmpmaskfake == 0)
557 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
558 else
559 icp->icmp_mask = V_icmpmaskfake;
560 if (ip->ip_src.s_addr == 0) {
561 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
562 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
563 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
564 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
565 }
566 ifa_free(&ia->ia_ifa);
567reflect:
568 ip->ip_len += hlen; /* since ip_input deducts this */
569 ICMPSTAT_INC(icps_reflect);
570 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
571 icmp_reflect(m);
572 return;
573
574 case ICMP_REDIRECT:
575 if (V_log_redirect) {
576 u_long src, dst, gw;
577
578 src = ntohl(ip->ip_src.s_addr);
579 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
580 gw = ntohl(icp->icmp_gwaddr.s_addr);
581 printf("icmp redirect from %d.%d.%d.%d: "
582 "%d.%d.%d.%d => %d.%d.%d.%d\n",
583 (int)(src >> 24), (int)((src >> 16) & 0xff),
584 (int)((src >> 8) & 0xff), (int)(src & 0xff),
585 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
586 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
587 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
588 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
589 }
590 /*
591 * RFC1812 says we must ignore ICMP redirects if we
592 * are acting as router.
593 */
594 if (V_drop_redirect || V_ipforwarding)
595 break;
596 if (code > 3)
597 goto badcode;
598 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
599 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
600 ICMPSTAT_INC(icps_badlen);
601 break;
602 }
603 /*
604 * Short circuit routing redirects to force
605 * immediate change in the kernel's routing
606 * tables. The message is also handed to anyone
607 * listening on a raw socket (e.g. the routing
608 * daemon for use in updating its tables).
609 */
610 icmpgw.sin_addr = ip->ip_src;
611 icmpdst.sin_addr = icp->icmp_gwaddr;
612#ifdef ICMPPRINTFS
613 if (icmpprintfs) {
614 char buf[4 * sizeof "123"];
615 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
616
617 printf("redirect dst %s to %s\n",
618 buf, inet_ntoa(icp->icmp_gwaddr));
619 }
620#endif
621 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
622 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
623 in_rtredirect((struct sockaddr *)&icmpsrc,
624 (struct sockaddr *)&icmpdst,
625 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
626 (struct sockaddr *)&icmpgw, fibnum);
627 }
628 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
629#ifdef IPSEC
630 key_sa_routechange((struct sockaddr *)&icmpsrc);
631#endif
632 break;
633
634 /*
635 * No kernel processing for the following;
636 * just fall through to send to raw listener.
637 */
638 case ICMP_ECHOREPLY:
639 case ICMP_ROUTERADVERT:
640 case ICMP_ROUTERSOLICIT:
641 case ICMP_TSTAMPREPLY:
642 case ICMP_IREQREPLY:
643 case ICMP_MASKREPLY:
644 default:
645 break;
646 }
647
648raw:
649 rip_input(m, off);
650 return;
651
652freeit:
653 m_freem(m);
654}
655
656/*
657 * Reflect the ip packet back to the source
658 */
659static void
660icmp_reflect(struct mbuf *m)
661{
662 struct ip *ip = mtod(m, struct ip *);
663 struct ifaddr *ifa;
664 struct ifnet *ifp;
665 struct in_ifaddr *ia;
666 struct in_addr t;
667 struct mbuf *opts = 0;
668 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
669
670 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
671 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
672 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
673 m_freem(m); /* Bad return address */
674 ICMPSTAT_INC(icps_badaddr);
675 goto done; /* Ip_output() will check for broadcast */
676 }
677
678 m_addr_changed(m);
679
680 t = ip->ip_dst;
681 ip->ip_dst = ip->ip_src;
682
683 /*
684 * Source selection for ICMP replies:
685 *
686 * If the incoming packet was addressed directly to one of our
687 * own addresses, use dst as the src for the reply.
688 */
689 IN_IFADDR_RLOCK();
690 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
691 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
692 t = IA_SIN(ia)->sin_addr;
693 IN_IFADDR_RUNLOCK();
694 goto match;
695 }
696 }
697 IN_IFADDR_RUNLOCK();
698
699 /*
700 * If the incoming packet was addressed to one of our broadcast
701 * addresses, use the first non-broadcast address which corresponds
702 * to the incoming interface.
703 */
704 ifp = m->m_pkthdr.rcvif;
705 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
706 IF_ADDR_RLOCK(ifp);
707 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
708 if (ifa->ifa_addr->sa_family != AF_INET)
709 continue;
710 ia = ifatoia(ifa);
711 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
712 t.s_addr) {
713 t = IA_SIN(ia)->sin_addr;
714 IF_ADDR_RUNLOCK(ifp);
715 goto match;
716 }
717 }
718 IF_ADDR_RUNLOCK(ifp);
719 }
720 /*
721 * If the packet was transiting through us, use the address of
722 * the interface the packet came through in. If that interface
723 * doesn't have a suitable IP address, the normal selection
724 * criteria apply.
725 */
726 if (V_icmp_rfi && ifp != NULL) {
727 IF_ADDR_RLOCK(ifp);
728 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
729 if (ifa->ifa_addr->sa_family != AF_INET)
730 continue;
731 ia = ifatoia(ifa);
732 t = IA_SIN(ia)->sin_addr;
733 IF_ADDR_RUNLOCK(ifp);
734 goto match;
735 }
736 IF_ADDR_RUNLOCK(ifp);
737 }
738 /*
739 * If the incoming packet was not addressed directly to us, use
740 * designated interface for icmp replies specified by sysctl
741 * net.inet.icmp.reply_src (default not set). Otherwise continue
742 * with normal source selection.
743 */
744 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
745 IF_ADDR_RLOCK(ifp);
746 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
747 if (ifa->ifa_addr->sa_family != AF_INET)
748 continue;
749 ia = ifatoia(ifa);
750 t = IA_SIN(ia)->sin_addr;
751 IF_ADDR_RUNLOCK(ifp);
752 goto match;
753 }
754 IF_ADDR_RUNLOCK(ifp);
755 }
756 /*
757 * If the packet was transiting through us, use the address of
758 * the interface that is the closest to the packet source.
759 * When we don't have a route back to the packet source, stop here
760 * and drop the packet.
761 */
762 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
763 if (ia == NULL) {
764 m_freem(m);
765 ICMPSTAT_INC(icps_noroute);
766 goto done;
767 }
768 t = IA_SIN(ia)->sin_addr;
769 ifa_free(&ia->ia_ifa);
770match:
771#ifdef MAC
772 mac_netinet_icmp_replyinplace(m);
773#endif
774 ip->ip_src = t;
775 ip->ip_ttl = V_ip_defttl;
776
777 if (optlen > 0) {
778 register u_char *cp;
779 int opt, cnt;
780 u_int len;
781
782 /*
783 * Retrieve any source routing from the incoming packet;
784 * add on any record-route or timestamp options.
785 */
786 cp = (u_char *) (ip + 1);
787 if ((opts = ip_srcroute(m)) == 0 &&
788 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
789 opts->m_len = sizeof(struct in_addr);
790 mtod(opts, struct in_addr *)->s_addr = 0;
791 }
792 if (opts) {
793#ifdef ICMPPRINTFS
794 if (icmpprintfs)
795 printf("icmp_reflect optlen %d rt %d => ",
796 optlen, opts->m_len);
797#endif
798 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
799 opt = cp[IPOPT_OPTVAL];
800 if (opt == IPOPT_EOL)
801 break;
802 if (opt == IPOPT_NOP)
803 len = 1;
804 else {
805 if (cnt < IPOPT_OLEN + sizeof(*cp))
806 break;
807 len = cp[IPOPT_OLEN];
808 if (len < IPOPT_OLEN + sizeof(*cp) ||
809 len > cnt)
810 break;
811 }
812 /*
813 * Should check for overflow, but it "can't happen"
814 */
815 if (opt == IPOPT_RR || opt == IPOPT_TS ||
816 opt == IPOPT_SECURITY) {
817 bcopy((caddr_t)cp,
818 mtod(opts, caddr_t) + opts->m_len, len);
819 opts->m_len += len;
820 }
821 }
822 /* Terminate & pad, if necessary */
823 cnt = opts->m_len % 4;
824 if (cnt) {
825 for (; cnt < 4; cnt++) {
826 *(mtod(opts, caddr_t) + opts->m_len) =
827 IPOPT_EOL;
828 opts->m_len++;
829 }
830 }
831#ifdef ICMPPRINTFS
832 if (icmpprintfs)
833 printf("%d\n", opts->m_len);
834#endif
835 }
836 /*
837 * Now strip out original options by copying rest of first
838 * mbuf's data back, and adjust the IP length.
839 */
840 ip->ip_len -= optlen;
841 ip->ip_v = IPVERSION;
842 ip->ip_hl = 5;
843 m->m_len -= optlen;
844 if (m->m_flags & M_PKTHDR)
845 m->m_pkthdr.len -= optlen;
846 optlen += sizeof(struct ip);
847 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
848 (unsigned)(m->m_len - sizeof(struct ip)));
849 }
850 m_tag_delete_nonpersistent(m);
851 m->m_flags &= ~(M_BCAST|M_MCAST);
852 icmp_send(m, opts);
853done:
854 if (opts)
855 (void)m_free(opts);
856}
857
858/*
859 * Send an icmp packet back to the ip level,
860 * after supplying a checksum.
861 */
862static void
863icmp_send(struct mbuf *m, struct mbuf *opts)
864{
865 register struct ip *ip = mtod(m, struct ip *);
866 register int hlen;
867 register struct icmp *icp;
868
869 hlen = ip->ip_hl << 2;
870 m->m_data += hlen;
871 m->m_len -= hlen;
872 icp = mtod(m, struct icmp *);
873 icp->icmp_cksum = 0;
874 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
875 m->m_data -= hlen;
876 m->m_len += hlen;
877 m->m_pkthdr.rcvif = (struct ifnet *)0;
878#ifdef ICMPPRINTFS
879 if (icmpprintfs) {
880 char buf[4 * sizeof "123"];
881 strcpy(buf, inet_ntoa(ip->ip_dst));
882 printf("icmp_send dst %s src %s\n",
883 buf, inet_ntoa(ip->ip_src));
884 }
885#endif
886 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
887}
888
889/*
890 * Return milliseconds since 00:00 GMT in network format.
891 */
892uint32_t
893iptime(void)
894{
895 struct timeval atv;
896 u_long t;
897
898 getmicrotime(&atv);
899 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
900 return (htonl(t));
901}
902
903/*
904 * Return the next larger or smaller MTU plateau (table from RFC 1191)
905 * given current value MTU. If DIR is less than zero, a larger plateau
906 * is returned; otherwise, a smaller value is returned.
907 */
908int
909ip_next_mtu(int mtu, int dir)
910{
911 static int mtutab[] = {
912 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
913 296, 68, 0
914 };
915 int i, size;
916
917 size = (sizeof mtutab) / (sizeof mtutab[0]);
918 if (dir >= 0) {
919 for (i = 0; i < size; i++)
920 if (mtu > mtutab[i])
921 return mtutab[i];
922 } else {
923 for (i = size - 1; i >= 0; i--)
924 if (mtu < mtutab[i])
925 return mtutab[i];
926 if (mtu == mtutab[0])
927 return mtutab[0];
928 }
929 return 0;
930}
931#endif /* INET */
932
933
934/*
935 * badport_bandlim() - check for ICMP bandwidth limit
936 *
937 * Return 0 if it is ok to send an ICMP error response, -1 if we have
938 * hit our bandwidth limit and it is not ok.
939 *
940 * If icmplim is <= 0, the feature is disabled and 0 is returned.
941 *
942 * For now we separate the TCP and UDP subsystems w/ different 'which'
943 * values. We may eventually remove this separation (and simplify the
944 * code further).
945 *
946 * Note that the printing of the error message is delayed so we can
947 * properly print the icmp error rate that the system was trying to do
948 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
949 * the 'final' error, but it doesn't make sense to solve the printing
950 * delay with more complex code.
951 */
952
953int
954badport_bandlim(int which)
955{
956
957#define N(a) (sizeof (a) / sizeof (a[0]))
958 static struct rate {
959 const char *type;
960 struct timeval lasttime;
961 int curpps;
962 } rates[BANDLIM_MAX+1] = {
963 { "icmp unreach response" },
964 { "icmp ping response" },
965 { "icmp tstamp response" },
966 { "closed port RST response" },
967 { "open port RST response" },
968 { "icmp6 unreach response" },
969 { "sctp ootb response" }
970 };
971
972 /*
973 * Return ok status if feature disabled or argument out of range.
974 */
975 if (V_icmplim > 0 && (u_int) which < N(rates)) {
976 struct rate *r = &rates[which];
977 int opps = r->curpps;
978
979 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
980 return -1; /* discard packet */
981 /*
982 * If we've dropped below the threshold after having
983 * rate-limited traffic print the message. This preserves
984 * the previous behaviour at the expense of added complexity.
985 */
986 if (V_icmplim_output && opps > V_icmplim)
987 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
988 r->type, opps, V_icmplim);
989 }
990 return 0; /* okay to send packet */
991#undef N
992}