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 196039 2009-08-02 19:43:32Z rwatson $");
34
35#include "opt_ipsec.h"
36
37#include <sys/param.h>
38#include <sys/systm.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#include <net/vnet.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
79VNET_DEFINE(struct icmpstat, icmpstat);
80static VNET_DEFINE(int, icmpmaskrepl);
81static VNET_DEFINE(u_int, icmpmaskfake);
82static VNET_DEFINE(int, drop_redirect);
83static VNET_DEFINE(int, log_redirect);
84static VNET_DEFINE(int, icmplim);
85static VNET_DEFINE(int, icmplim_output);
86static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
87static VNET_DEFINE(int, icmp_rfi);
88static VNET_DEFINE(int, icmp_quotelen);
89static VNET_DEFINE(int, icmpbmcastecho);
90
91#define V_icmpmaskrepl VNET(icmpmaskrepl)
92#define V_icmpmaskfake VNET(icmpmaskfake)
93#define V_drop_redirect VNET(drop_redirect)
94#define V_log_redirect VNET(log_redirect)
95#define V_icmplim VNET(icmplim)
96#define V_icmplim_output VNET(icmplim_output)
97#define V_reply_src VNET(reply_src)
98#define V_icmp_rfi VNET(icmp_rfi)
99#define V_icmp_quotelen VNET(icmp_quotelen)
100#define V_icmpbmcastecho VNET(icmpbmcastecho)
101
102SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
103 &VNET_NAME(icmpstat), icmpstat, "");
104
105SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
106 &VNET_NAME(icmpmaskrepl), 0,
107 "Reply to ICMP Address Mask Request packets.");
108
109SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
110 &VNET_NAME(icmpmaskfake), 0,
111 "Fake reply to ICMP Address Mask Request packets.");
112
113SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
114 &VNET_NAME(drop_redirect), 0,
115 "Ignore ICMP redirects");
116
117SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
118 &VNET_NAME(log_redirect), 0,
119 "Log ICMP redirects to the console");
120
121SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
122 &VNET_NAME(icmplim), 0,
123 "Maximum number of ICMP responses per second");
124
125SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
126 &VNET_NAME(icmplim_output), 0,
127 "Enable rate limiting of ICMP responses");
128
129SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
130 &VNET_NAME(reply_src), IFNAMSIZ,
131 "icmp reply source for non-local packets.");
132
133SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
134 &VNET_NAME(icmp_rfi), 0,
135 "ICMP reply from incoming interface for non-local packets");
136
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 */
144
145SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
146 &VNET_NAME(icmpbmcastecho), 0,
147 "");
148
149
150#ifdef ICMPPRINTFS
151int icmpprintfs = 0;
152#endif
153
154static void icmp_reflect(struct mbuf *);
155static void icmp_send(struct mbuf *, struct mbuf *);
156
157extern struct protosw inetsw[];
158
159void
160icmp_init(void)
161{
162
163 V_icmpmaskrepl = 0;
164 V_icmpmaskfake = 0;
165 V_drop_redirect = 0;
166 V_log_redirect = 0;
167 V_icmplim = 200;
168 V_icmplim_output = 1;
169 V_icmp_rfi = 0;
170 V_icmp_quotelen = 8;
171 V_icmpbmcastecho = 0;
172}
173
174/*
175 * Kernel module interface for updating icmpstat. The argument is an index
176 * into icmpstat treated as an array of u_long. While this encodes the
177 * general layout of icmpstat into the caller, it doesn't encode its
178 * location, so that future changes to add, for example, per-CPU stats
179 * support won't cause binary compatibility problems for kernel modules.
180 */
181void
182kmod_icmpstat_inc(int statnum)
183{
184
185 (*((u_long *)&V_icmpstat + statnum))++;
186}
187
188/*
189 * Generate an error packet of type error
190 * in response to bad packet ip.
191 */
192void
193icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
194{
195 register struct ip *oip = mtod(n, struct ip *), *nip;
196 register unsigned oiphlen = oip->ip_hl << 2;
197 register struct icmp *icp;
198 register struct mbuf *m;
199 unsigned icmplen, icmpelen, nlen;
200
201 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
202#ifdef ICMPPRINTFS
203 if (icmpprintfs)
204 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
205#endif
206 if (type != ICMP_REDIRECT)
207 ICMPSTAT_INC(icps_error);
208 /*
209 * Don't send error:
210 * if the original packet was encrypted.
211 * if not the first fragment of message.
212 * in response to a multicast or broadcast packet.
213 * if the old packet protocol was an ICMP error message.
214 */
215 if (n->m_flags & M_DECRYPTED)
216 goto freeit;
217 if (oip->ip_off & ~(IP_MF|IP_DF))
218 goto freeit;
219 if (n->m_flags & (M_BCAST|M_MCAST))
220 goto freeit;
221 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
222 n->m_len >= oiphlen + ICMP_MINLEN &&
223 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
224 ICMPSTAT_INC(icps_oldicmp);
225 goto freeit;
226 }
227 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
228 if (oiphlen + 8 > n->m_len)
229 goto freeit;
230 /*
231 * Calculate length to quote from original packet and
232 * prevent the ICMP mbuf from overflowing.
233 * Unfortunatly this is non-trivial since ip_forward()
234 * sends us truncated packets.
235 */
236 nlen = m_length(n, NULL);
237 if (oip->ip_p == IPPROTO_TCP) {
238 struct tcphdr *th;
239 int tcphlen;
240
241 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
242 n->m_next == NULL)
243 goto stdreply;
244 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
245 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
246 goto freeit;
247 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
248 tcphlen = th->th_off << 2;
249 if (tcphlen < sizeof(struct tcphdr))
250 goto freeit;
251 if (oip->ip_len < oiphlen + tcphlen)
252 goto freeit;
253 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
254 goto stdreply;
255 if (n->m_len < oiphlen + tcphlen &&
256 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
257 goto freeit;
258 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen));
259 } else
260stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen));
261
262 icmplen = min(oiphlen + icmpelen, nlen);
263 if (icmplen < sizeof(struct ip))
264 goto freeit;
265
266 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
267 m = m_gethdr(M_DONTWAIT, MT_DATA);
268 else
269 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
270 if (m == NULL)
271 goto freeit;
272#ifdef MAC
273 mac_netinet_icmp_reply(n, m);
274#endif
275 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
276 m_align(m, ICMP_MINLEN + icmplen);
277 m->m_len = ICMP_MINLEN + icmplen;
278
279 /* XXX MRT make the outgoing packet use the same FIB
280 * that was associated with the incoming packet
281 */
282 M_SETFIB(m, M_GETFIB(n));
283 icp = mtod(m, struct icmp *);
284 ICMPSTAT_INC(icps_outhist[type]);
285 icp->icmp_type = type;
286 if (type == ICMP_REDIRECT)
287 icp->icmp_gwaddr.s_addr = dest;
288 else {
289 icp->icmp_void = 0;
290 /*
291 * The following assignments assume an overlay with the
292 * just zeroed icmp_void field.
293 */
294 if (type == ICMP_PARAMPROB) {
295 icp->icmp_pptr = code;
296 code = 0;
297 } else if (type == ICMP_UNREACH &&
298 code == ICMP_UNREACH_NEEDFRAG && mtu) {
299 icp->icmp_nextmtu = htons(mtu);
300 }
301 }
302 icp->icmp_code = code;
303
304 /*
305 * Copy the quotation into ICMP message and
306 * convert quoted IP header back to network representation.
307 */
308 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
309 nip = &icp->icmp_ip;
310 nip->ip_len = htons(nip->ip_len);
311 nip->ip_off = htons(nip->ip_off);
312
313 /*
314 * Set up ICMP message mbuf and copy old IP header (without options
315 * in front of ICMP message.
316 * If the original mbuf was meant to bypass the firewall, the error
317 * reply should bypass as well.
318 */
319 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
320 m->m_data -= sizeof(struct ip);
321 m->m_len += sizeof(struct ip);
322 m->m_pkthdr.len = m->m_len;
323 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
324 nip = mtod(m, struct ip *);
325 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
326 nip->ip_len = m->m_len;
327 nip->ip_v = IPVERSION;
328 nip->ip_hl = 5;
329 nip->ip_p = IPPROTO_ICMP;
330 nip->ip_tos = 0;
331 icmp_reflect(m);
332
333freeit:
334 m_freem(n);
335}
336
337/*
338 * Process a received ICMP message.
339 */
340void
341icmp_input(struct mbuf *m, int off)
342{
343 struct icmp *icp;
344 struct in_ifaddr *ia;
345 struct ip *ip = mtod(m, struct ip *);
346 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
347 int hlen = off;
348 int icmplen = ip->ip_len;
349 int i, code;
350 void (*ctlfunc)(int, struct sockaddr *, void *);
351 int fibnum;
352
353 /*
354 * Locate icmp structure in mbuf, and check
355 * that not corrupted and of at least minimum length.
356 */
357#ifdef ICMPPRINTFS
358 if (icmpprintfs) {
359 char buf[4 * sizeof "123"];
360 strcpy(buf, inet_ntoa(ip->ip_src));
361 printf("icmp_input from %s to %s, len %d\n",
362 buf, inet_ntoa(ip->ip_dst), icmplen);
363 }
364#endif
365 if (icmplen < ICMP_MINLEN) {
366 ICMPSTAT_INC(icps_tooshort);
367 goto freeit;
368 }
369 i = hlen + min(icmplen, ICMP_ADVLENMIN);
370 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
371 ICMPSTAT_INC(icps_tooshort);
372 return;
373 }
374 ip = mtod(m, struct ip *);
375 m->m_len -= hlen;
376 m->m_data += hlen;
377 icp = mtod(m, struct icmp *);
378 if (in_cksum(m, icmplen)) {
379 ICMPSTAT_INC(icps_checksum);
380 goto freeit;
381 }
382 m->m_len += hlen;
383 m->m_data -= hlen;
384
385 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
386 /*
387 * Deliver very specific ICMP type only.
388 */
389 switch (icp->icmp_type) {
390 case ICMP_UNREACH:
391 case ICMP_TIMXCEED:
392 break;
393 default:
394 goto freeit;
395 }
396 }
397
398#ifdef ICMPPRINTFS
399 if (icmpprintfs)
400 printf("icmp_input, type %d code %d\n", icp->icmp_type,
401 icp->icmp_code);
402#endif
403
404 /*
405 * Message type specific processing.
406 */
407 if (icp->icmp_type > ICMP_MAXTYPE)
408 goto raw;
409
410 /* Initialize */
411 bzero(&icmpsrc, sizeof(icmpsrc));
412 icmpsrc.sin_len = sizeof(struct sockaddr_in);
413 icmpsrc.sin_family = AF_INET;
414 bzero(&icmpdst, sizeof(icmpdst));
415 icmpdst.sin_len = sizeof(struct sockaddr_in);
416 icmpdst.sin_family = AF_INET;
417 bzero(&icmpgw, sizeof(icmpgw));
418 icmpgw.sin_len = sizeof(struct sockaddr_in);
419 icmpgw.sin_family = AF_INET;
420
421 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
422 code = icp->icmp_code;
423 switch (icp->icmp_type) {
424
425 case ICMP_UNREACH:
426 switch (code) {
427 case ICMP_UNREACH_NET:
428 case ICMP_UNREACH_HOST:
429 case ICMP_UNREACH_SRCFAIL:
430 case ICMP_UNREACH_NET_UNKNOWN:
431 case ICMP_UNREACH_HOST_UNKNOWN:
432 case ICMP_UNREACH_ISOLATED:
433 case ICMP_UNREACH_TOSNET:
434 case ICMP_UNREACH_TOSHOST:
435 case ICMP_UNREACH_HOST_PRECEDENCE:
436 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
437 code = PRC_UNREACH_NET;
438 break;
439
440 case ICMP_UNREACH_NEEDFRAG:
441 code = PRC_MSGSIZE;
442 break;
443
444 /*
445 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
446 * Treat subcodes 2,3 as immediate RST
447 */
448 case ICMP_UNREACH_PROTOCOL:
449 case ICMP_UNREACH_PORT:
450 code = PRC_UNREACH_PORT;
451 break;
452
453 case ICMP_UNREACH_NET_PROHIB:
454 case ICMP_UNREACH_HOST_PROHIB:
455 case ICMP_UNREACH_FILTER_PROHIB:
456 code = PRC_UNREACH_ADMIN_PROHIB;
457 break;
458
459 default:
460 goto badcode;
461 }
462 goto deliver;
463
464 case ICMP_TIMXCEED:
465 if (code > 1)
466 goto badcode;
467 code += PRC_TIMXCEED_INTRANS;
468 goto deliver;
469
470 case ICMP_PARAMPROB:
471 if (code > 1)
472 goto badcode;
473 code = PRC_PARAMPROB;
474 goto deliver;
475
476 case ICMP_SOURCEQUENCH:
477 if (code)
478 goto badcode;
479 code = PRC_QUENCH;
480 deliver:
481 /*
482 * Problem with datagram; advise higher level routines.
483 */
484 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
485 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
486 ICMPSTAT_INC(icps_badlen);
487 goto freeit;
488 }
489 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
490 /* Discard ICMP's in response to multicast packets */
491 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
492 goto badcode;
493#ifdef ICMPPRINTFS
494 if (icmpprintfs)
495 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
496#endif
497 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
498 /*
499 * XXX if the packet contains [IPv4 AH TCP], we can't make a
500 * notification to TCP layer.
501 */
502 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
503 if (ctlfunc)
504 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
505 (void *)&icp->icmp_ip);
506 break;
507
508 badcode:
509 ICMPSTAT_INC(icps_badcode);
510 break;
511
512 case ICMP_ECHO:
513 if (!V_icmpbmcastecho
514 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
515 ICMPSTAT_INC(icps_bmcastecho);
516 break;
517 }
518 icp->icmp_type = ICMP_ECHOREPLY;
519 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
520 goto freeit;
521 else
522 goto reflect;
523
524 case ICMP_TSTAMP:
525 if (!V_icmpbmcastecho
526 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
527 ICMPSTAT_INC(icps_bmcasttstamp);
528 break;
529 }
530 if (icmplen < ICMP_TSLEN) {
531 ICMPSTAT_INC(icps_badlen);
532 break;
533 }
534 icp->icmp_type = ICMP_TSTAMPREPLY;
535 icp->icmp_rtime = iptime();
536 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
537 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
538 goto freeit;
539 else
540 goto reflect;
541
542 case ICMP_MASKREQ:
543 if (V_icmpmaskrepl == 0)
544 break;
545 /*
546 * We are not able to respond with all ones broadcast
547 * unless we receive it over a point-to-point interface.
548 */
549 if (icmplen < ICMP_MASKLEN)
550 break;
551 switch (ip->ip_dst.s_addr) {
552
553 case INADDR_BROADCAST:
554 case INADDR_ANY:
555 icmpdst.sin_addr = ip->ip_src;
556 break;
557
558 default:
559 icmpdst.sin_addr = ip->ip_dst;
560 }
561 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
562 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
563 if (ia == NULL)
564 break;
565 if (ia->ia_ifp == NULL) {
566 ifa_free(&ia->ia_ifa);
567 break;
568 }
569 icp->icmp_type = ICMP_MASKREPLY;
570 if (V_icmpmaskfake == 0)
571 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
572 else
573 icp->icmp_mask = V_icmpmaskfake;
574 if (ip->ip_src.s_addr == 0) {
575 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
576 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
577 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
578 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
579 }
580 ifa_free(&ia->ia_ifa);
581reflect:
582 ip->ip_len += hlen; /* since ip_input deducts this */
583 ICMPSTAT_INC(icps_reflect);
584 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
585 icmp_reflect(m);
586 return;
587
588 case ICMP_REDIRECT:
589 if (V_log_redirect) {
590 u_long src, dst, gw;
591
592 src = ntohl(ip->ip_src.s_addr);
593 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
594 gw = ntohl(icp->icmp_gwaddr.s_addr);
595 printf("icmp redirect from %d.%d.%d.%d: "
596 "%d.%d.%d.%d => %d.%d.%d.%d\n",
597 (int)(src >> 24), (int)((src >> 16) & 0xff),
598 (int)((src >> 8) & 0xff), (int)(src & 0xff),
599 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
600 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
601 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
602 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
603 }
604 /*
605 * RFC1812 says we must ignore ICMP redirects if we
606 * are acting as router.
607 */
608 if (V_drop_redirect || V_ipforwarding)
609 break;
610 if (code > 3)
611 goto badcode;
612 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
613 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
614 ICMPSTAT_INC(icps_badlen);
615 break;
616 }
617 /*
618 * Short circuit routing redirects to force
619 * immediate change in the kernel's routing
620 * tables. The message is also handed to anyone
621 * listening on a raw socket (e.g. the routing
622 * daemon for use in updating its tables).
623 */
624 icmpgw.sin_addr = ip->ip_src;
625 icmpdst.sin_addr = icp->icmp_gwaddr;
626#ifdef ICMPPRINTFS
627 if (icmpprintfs) {
628 char buf[4 * sizeof "123"];
629 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
630
631 printf("redirect dst %s to %s\n",
632 buf, inet_ntoa(icp->icmp_gwaddr));
633 }
634#endif
635 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
636 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
637 in_rtredirect((struct sockaddr *)&icmpsrc,
638 (struct sockaddr *)&icmpdst,
639 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
640 (struct sockaddr *)&icmpgw, fibnum);
641 }
642 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
643#ifdef IPSEC
644 key_sa_routechange((struct sockaddr *)&icmpsrc);
645#endif
646 break;
647
648 /*
649 * No kernel processing for the following;
650 * just fall through to send to raw listener.
651 */
652 case ICMP_ECHOREPLY:
653 case ICMP_ROUTERADVERT:
654 case ICMP_ROUTERSOLICIT:
655 case ICMP_TSTAMPREPLY:
656 case ICMP_IREQREPLY:
657 case ICMP_MASKREPLY:
658 default:
659 break;
660 }
661
662raw:
663 rip_input(m, off);
664 return;
665
666freeit:
667 m_freem(m);
668}
669
670/*
671 * Reflect the ip packet back to the source
672 */
673static void
674icmp_reflect(struct mbuf *m)
675{
676 struct ip *ip = mtod(m, struct ip *);
677 struct ifaddr *ifa;
678 struct ifnet *ifp;
679 struct in_ifaddr *ia;
680 struct in_addr t;
681 struct mbuf *opts = 0;
682 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
683
684 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
685 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
686 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
687 m_freem(m); /* Bad return address */
688 ICMPSTAT_INC(icps_badaddr);
689 goto done; /* Ip_output() will check for broadcast */
690 }
691
692 t = ip->ip_dst;
693 ip->ip_dst = ip->ip_src;
694
695 /*
696 * Source selection for ICMP replies:
697 *
698 * If the incoming packet was addressed directly to one of our
699 * own addresses, use dst as the src for the reply.
700 */
701 IN_IFADDR_RLOCK();
702 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
703 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
704 t = IA_SIN(ia)->sin_addr;
705 IN_IFADDR_RUNLOCK();
706 goto match;
707 }
708 }
709 IN_IFADDR_RUNLOCK();
710
711 /*
712 * If the incoming packet was addressed to one of our broadcast
713 * addresses, use the first non-broadcast address which corresponds
714 * to the incoming interface.
715 */
716 ifp = m->m_pkthdr.rcvif;
717 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
718 IF_ADDR_LOCK(ifp);
719 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
720 if (ifa->ifa_addr->sa_family != AF_INET)
721 continue;
722 ia = ifatoia(ifa);
723 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
724 t.s_addr) {
725 t = IA_SIN(ia)->sin_addr;
726 IF_ADDR_UNLOCK(ifp);
727 goto match;
728 }
729 }
730 IF_ADDR_UNLOCK(ifp);
731 }
732 /*
733 * If the packet was transiting through us, use the address of
734 * the interface the packet came through in. If that interface
735 * doesn't have a suitable IP address, the normal selection
736 * criteria apply.
737 */
738 if (V_icmp_rfi && ifp != NULL) {
739 IF_ADDR_LOCK(ifp);
740 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
741 if (ifa->ifa_addr->sa_family != AF_INET)
742 continue;
743 ia = ifatoia(ifa);
744 t = IA_SIN(ia)->sin_addr;
745 IF_ADDR_UNLOCK(ifp);
746 goto match;
747 }
748 IF_ADDR_UNLOCK(ifp);
749 }
750 /*
751 * If the incoming packet was not addressed directly to us, use
752 * designated interface for icmp replies specified by sysctl
753 * net.inet.icmp.reply_src (default not set). Otherwise continue
754 * with normal source selection.
755 */
756 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
757 IF_ADDR_LOCK(ifp);
758 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
759 if (ifa->ifa_addr->sa_family != AF_INET)
760 continue;
761 ia = ifatoia(ifa);
762 t = IA_SIN(ia)->sin_addr;
763 IF_ADDR_UNLOCK(ifp);
764 goto match;
765 }
766 IF_ADDR_UNLOCK(ifp);
767 }
768 /*
769 * If the packet was transiting through us, use the address of
770 * the interface that is the closest to the packet source.
771 * When we don't have a route back to the packet source, stop here
772 * and drop the packet.
773 */
774 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
775 if (ia == NULL) {
776 m_freem(m);
777 ICMPSTAT_INC(icps_noroute);
778 goto done;
779 }
780 t = IA_SIN(ia)->sin_addr;
781 ifa_free(&ia->ia_ifa);
782match:
783#ifdef MAC
784 mac_netinet_icmp_replyinplace(m);
785#endif
786 ip->ip_src = t;
787 ip->ip_ttl = V_ip_defttl;
788
789 if (optlen > 0) {
790 register u_char *cp;
791 int opt, cnt;
792 u_int len;
793
794 /*
795 * Retrieve any source routing from the incoming packet;
796 * add on any record-route or timestamp options.
797 */
798 cp = (u_char *) (ip + 1);
799 if ((opts = ip_srcroute(m)) == 0 &&
800 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
801 opts->m_len = sizeof(struct in_addr);
802 mtod(opts, struct in_addr *)->s_addr = 0;
803 }
804 if (opts) {
805#ifdef ICMPPRINTFS
806 if (icmpprintfs)
807 printf("icmp_reflect optlen %d rt %d => ",
808 optlen, opts->m_len);
809#endif
810 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
811 opt = cp[IPOPT_OPTVAL];
812 if (opt == IPOPT_EOL)
813 break;
814 if (opt == IPOPT_NOP)
815 len = 1;
816 else {
817 if (cnt < IPOPT_OLEN + sizeof(*cp))
818 break;
819 len = cp[IPOPT_OLEN];
820 if (len < IPOPT_OLEN + sizeof(*cp) ||
821 len > cnt)
822 break;
823 }
824 /*
825 * Should check for overflow, but it "can't happen"
826 */
827 if (opt == IPOPT_RR || opt == IPOPT_TS ||
828 opt == IPOPT_SECURITY) {
829 bcopy((caddr_t)cp,
830 mtod(opts, caddr_t) + opts->m_len, len);
831 opts->m_len += len;
832 }
833 }
834 /* Terminate & pad, if necessary */
835 cnt = opts->m_len % 4;
836 if (cnt) {
837 for (; cnt < 4; cnt++) {
838 *(mtod(opts, caddr_t) + opts->m_len) =
839 IPOPT_EOL;
840 opts->m_len++;
841 }
842 }
843#ifdef ICMPPRINTFS
844 if (icmpprintfs)
845 printf("%d\n", opts->m_len);
846#endif
847 }
848 /*
849 * Now strip out original options by copying rest of first
850 * mbuf's data back, and adjust the IP length.
851 */
852 ip->ip_len -= optlen;
853 ip->ip_v = IPVERSION;
854 ip->ip_hl = 5;
855 m->m_len -= optlen;
856 if (m->m_flags & M_PKTHDR)
857 m->m_pkthdr.len -= optlen;
858 optlen += sizeof(struct ip);
859 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
860 (unsigned)(m->m_len - sizeof(struct ip)));
861 }
862 m_tag_delete_nonpersistent(m);
863 m->m_flags &= ~(M_BCAST|M_MCAST);
864 icmp_send(m, opts);
865done:
866 if (opts)
867 (void)m_free(opts);
868}
869
870/*
871 * Send an icmp packet back to the ip level,
872 * after supplying a checksum.
873 */
874static void
875icmp_send(struct mbuf *m, struct mbuf *opts)
876{
877 register struct ip *ip = mtod(m, struct ip *);
878 register int hlen;
879 register struct icmp *icp;
880
881 hlen = ip->ip_hl << 2;
882 m->m_data += hlen;
883 m->m_len -= hlen;
884 icp = mtod(m, struct icmp *);
885 icp->icmp_cksum = 0;
886 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
887 m->m_data -= hlen;
888 m->m_len += hlen;
889 m->m_pkthdr.rcvif = (struct ifnet *)0;
890#ifdef ICMPPRINTFS
891 if (icmpprintfs) {
892 char buf[4 * sizeof "123"];
893 strcpy(buf, inet_ntoa(ip->ip_dst));
894 printf("icmp_send dst %s src %s\n",
895 buf, inet_ntoa(ip->ip_src));
896 }
897#endif
898 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
899}
900
901/*
902 * Return milliseconds since 00:00 GMT in network format.
903 */
904uint32_t
905iptime(void)
906{
907 struct timeval atv;
908 u_long t;
909
910 getmicrotime(&atv);
911 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
912 return (htonl(t));
913}
914
915/*
916 * Return the next larger or smaller MTU plateau (table from RFC 1191)
917 * given current value MTU. If DIR is less than zero, a larger plateau
918 * is returned; otherwise, a smaller value is returned.
919 */
920int
921ip_next_mtu(int mtu, int dir)
922{
923 static int mtutab[] = {
924 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
925 296, 68, 0
926 };
927 int i, size;
928
929 size = (sizeof mtutab) / (sizeof mtutab[0]);
930 if (dir >= 0) {
931 for (i = 0; i < size; i++)
932 if (mtu > mtutab[i])
933 return mtutab[i];
934 } else {
935 for (i = size - 1; i >= 0; i--)
936 if (mtu < mtutab[i])
937 return mtutab[i];
938 if (mtu == mtutab[0])
939 return mtutab[0];
940 }
941 return 0;
942}
943
944
945/*
946 * badport_bandlim() - check for ICMP bandwidth limit
947 *
948 * Return 0 if it is ok to send an ICMP error response, -1 if we have
949 * hit our bandwidth limit and it is not ok.
950 *
951 * If icmplim is <= 0, the feature is disabled and 0 is returned.
952 *
953 * For now we separate the TCP and UDP subsystems w/ different 'which'
954 * values. We may eventually remove this separation (and simplify the
955 * code further).
956 *
957 * Note that the printing of the error message is delayed so we can
958 * properly print the icmp error rate that the system was trying to do
959 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
960 * the 'final' error, but it doesn't make sense to solve the printing
961 * delay with more complex code.
962 */
963
964int
965badport_bandlim(int which)
966{
967
968#define N(a) (sizeof (a) / sizeof (a[0]))
969 static struct rate {
970 const char *type;
971 struct timeval lasttime;
972 int curpps;
973 } rates[BANDLIM_MAX+1] = {
974 { "icmp unreach response" },
975 { "icmp ping response" },
976 { "icmp tstamp response" },
977 { "closed port RST response" },
978 { "open port RST response" },
979 { "icmp6 unreach response" }
980 };
981
982 /*
983 * Return ok status if feature disabled or argument out of range.
984 */
985 if (V_icmplim > 0 && (u_int) which < N(rates)) {
986 struct rate *r = &rates[which];
987 int opps = r->curpps;
988
989 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
990 return -1; /* discard packet */
991 /*
992 * If we've dropped below the threshold after having
993 * rate-limited traffic print the message. This preserves
994 * the previous behaviour at the expense of added complexity.
995 */
996 if (V_icmplim_output && opps > V_icmplim)
997 printf("Limiting %s from %d to %d packets/sec\n",
998 r->type, opps, V_icmplim);
999 }
1000 return 0; /* okay to send packet */
1001#undef N
1002}
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 196039 2009-08-02 19:43:32Z rwatson $");
34
35#include "opt_ipsec.h"
36
37#include <sys/param.h>
38#include <sys/systm.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#include <net/vnet.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
79VNET_DEFINE(struct icmpstat, icmpstat);
80static VNET_DEFINE(int, icmpmaskrepl);
81static VNET_DEFINE(u_int, icmpmaskfake);
82static VNET_DEFINE(int, drop_redirect);
83static VNET_DEFINE(int, log_redirect);
84static VNET_DEFINE(int, icmplim);
85static VNET_DEFINE(int, icmplim_output);
86static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
87static VNET_DEFINE(int, icmp_rfi);
88static VNET_DEFINE(int, icmp_quotelen);
89static VNET_DEFINE(int, icmpbmcastecho);
90
91#define V_icmpmaskrepl VNET(icmpmaskrepl)
92#define V_icmpmaskfake VNET(icmpmaskfake)
93#define V_drop_redirect VNET(drop_redirect)
94#define V_log_redirect VNET(log_redirect)
95#define V_icmplim VNET(icmplim)
96#define V_icmplim_output VNET(icmplim_output)
97#define V_reply_src VNET(reply_src)
98#define V_icmp_rfi VNET(icmp_rfi)
99#define V_icmp_quotelen VNET(icmp_quotelen)
100#define V_icmpbmcastecho VNET(icmpbmcastecho)
101
102SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
103 &VNET_NAME(icmpstat), icmpstat, "");
104
105SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
106 &VNET_NAME(icmpmaskrepl), 0,
107 "Reply to ICMP Address Mask Request packets.");
108
109SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
110 &VNET_NAME(icmpmaskfake), 0,
111 "Fake reply to ICMP Address Mask Request packets.");
112
113SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
114 &VNET_NAME(drop_redirect), 0,
115 "Ignore ICMP redirects");
116
117SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
118 &VNET_NAME(log_redirect), 0,
119 "Log ICMP redirects to the console");
120
121SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
122 &VNET_NAME(icmplim), 0,
123 "Maximum number of ICMP responses per second");
124
125SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
126 &VNET_NAME(icmplim_output), 0,
127 "Enable rate limiting of ICMP responses");
128
129SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
130 &VNET_NAME(reply_src), IFNAMSIZ,
131 "icmp reply source for non-local packets.");
132
133SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
134 &VNET_NAME(icmp_rfi), 0,
135 "ICMP reply from incoming interface for non-local packets");
136
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 */
144
145SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
146 &VNET_NAME(icmpbmcastecho), 0,
147 "");
148
149
150#ifdef ICMPPRINTFS
151int icmpprintfs = 0;
152#endif
153
154static void icmp_reflect(struct mbuf *);
155static void icmp_send(struct mbuf *, struct mbuf *);
156
157extern struct protosw inetsw[];
158
159void
160icmp_init(void)
161{
162
163 V_icmpmaskrepl = 0;
164 V_icmpmaskfake = 0;
165 V_drop_redirect = 0;
166 V_log_redirect = 0;
167 V_icmplim = 200;
168 V_icmplim_output = 1;
169 V_icmp_rfi = 0;
170 V_icmp_quotelen = 8;
171 V_icmpbmcastecho = 0;
172}
173
174/*
175 * Kernel module interface for updating icmpstat. The argument is an index
176 * into icmpstat treated as an array of u_long. While this encodes the
177 * general layout of icmpstat into the caller, it doesn't encode its
178 * location, so that future changes to add, for example, per-CPU stats
179 * support won't cause binary compatibility problems for kernel modules.
180 */
181void
182kmod_icmpstat_inc(int statnum)
183{
184
185 (*((u_long *)&V_icmpstat + statnum))++;
186}
187
188/*
189 * Generate an error packet of type error
190 * in response to bad packet ip.
191 */
192void
193icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
194{
195 register struct ip *oip = mtod(n, struct ip *), *nip;
196 register unsigned oiphlen = oip->ip_hl << 2;
197 register struct icmp *icp;
198 register struct mbuf *m;
199 unsigned icmplen, icmpelen, nlen;
200
201 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
202#ifdef ICMPPRINTFS
203 if (icmpprintfs)
204 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
205#endif
206 if (type != ICMP_REDIRECT)
207 ICMPSTAT_INC(icps_error);
208 /*
209 * Don't send error:
210 * if the original packet was encrypted.
211 * if not the first fragment of message.
212 * in response to a multicast or broadcast packet.
213 * if the old packet protocol was an ICMP error message.
214 */
215 if (n->m_flags & M_DECRYPTED)
216 goto freeit;
217 if (oip->ip_off & ~(IP_MF|IP_DF))
218 goto freeit;
219 if (n->m_flags & (M_BCAST|M_MCAST))
220 goto freeit;
221 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
222 n->m_len >= oiphlen + ICMP_MINLEN &&
223 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
224 ICMPSTAT_INC(icps_oldicmp);
225 goto freeit;
226 }
227 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
228 if (oiphlen + 8 > n->m_len)
229 goto freeit;
230 /*
231 * Calculate length to quote from original packet and
232 * prevent the ICMP mbuf from overflowing.
233 * Unfortunatly this is non-trivial since ip_forward()
234 * sends us truncated packets.
235 */
236 nlen = m_length(n, NULL);
237 if (oip->ip_p == IPPROTO_TCP) {
238 struct tcphdr *th;
239 int tcphlen;
240
241 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
242 n->m_next == NULL)
243 goto stdreply;
244 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
245 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
246 goto freeit;
247 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
248 tcphlen = th->th_off << 2;
249 if (tcphlen < sizeof(struct tcphdr))
250 goto freeit;
251 if (oip->ip_len < oiphlen + tcphlen)
252 goto freeit;
253 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
254 goto stdreply;
255 if (n->m_len < oiphlen + tcphlen &&
256 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
257 goto freeit;
258 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen));
259 } else
260stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen));
261
262 icmplen = min(oiphlen + icmpelen, nlen);
263 if (icmplen < sizeof(struct ip))
264 goto freeit;
265
266 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
267 m = m_gethdr(M_DONTWAIT, MT_DATA);
268 else
269 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
270 if (m == NULL)
271 goto freeit;
272#ifdef MAC
273 mac_netinet_icmp_reply(n, m);
274#endif
275 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
276 m_align(m, ICMP_MINLEN + icmplen);
277 m->m_len = ICMP_MINLEN + icmplen;
278
279 /* XXX MRT make the outgoing packet use the same FIB
280 * that was associated with the incoming packet
281 */
282 M_SETFIB(m, M_GETFIB(n));
283 icp = mtod(m, struct icmp *);
284 ICMPSTAT_INC(icps_outhist[type]);
285 icp->icmp_type = type;
286 if (type == ICMP_REDIRECT)
287 icp->icmp_gwaddr.s_addr = dest;
288 else {
289 icp->icmp_void = 0;
290 /*
291 * The following assignments assume an overlay with the
292 * just zeroed icmp_void field.
293 */
294 if (type == ICMP_PARAMPROB) {
295 icp->icmp_pptr = code;
296 code = 0;
297 } else if (type == ICMP_UNREACH &&
298 code == ICMP_UNREACH_NEEDFRAG && mtu) {
299 icp->icmp_nextmtu = htons(mtu);
300 }
301 }
302 icp->icmp_code = code;
303
304 /*
305 * Copy the quotation into ICMP message and
306 * convert quoted IP header back to network representation.
307 */
308 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
309 nip = &icp->icmp_ip;
310 nip->ip_len = htons(nip->ip_len);
311 nip->ip_off = htons(nip->ip_off);
312
313 /*
314 * Set up ICMP message mbuf and copy old IP header (without options
315 * in front of ICMP message.
316 * If the original mbuf was meant to bypass the firewall, the error
317 * reply should bypass as well.
318 */
319 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
320 m->m_data -= sizeof(struct ip);
321 m->m_len += sizeof(struct ip);
322 m->m_pkthdr.len = m->m_len;
323 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
324 nip = mtod(m, struct ip *);
325 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
326 nip->ip_len = m->m_len;
327 nip->ip_v = IPVERSION;
328 nip->ip_hl = 5;
329 nip->ip_p = IPPROTO_ICMP;
330 nip->ip_tos = 0;
331 icmp_reflect(m);
332
333freeit:
334 m_freem(n);
335}
336
337/*
338 * Process a received ICMP message.
339 */
340void
341icmp_input(struct mbuf *m, int off)
342{
343 struct icmp *icp;
344 struct in_ifaddr *ia;
345 struct ip *ip = mtod(m, struct ip *);
346 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
347 int hlen = off;
348 int icmplen = ip->ip_len;
349 int i, code;
350 void (*ctlfunc)(int, struct sockaddr *, void *);
351 int fibnum;
352
353 /*
354 * Locate icmp structure in mbuf, and check
355 * that not corrupted and of at least minimum length.
356 */
357#ifdef ICMPPRINTFS
358 if (icmpprintfs) {
359 char buf[4 * sizeof "123"];
360 strcpy(buf, inet_ntoa(ip->ip_src));
361 printf("icmp_input from %s to %s, len %d\n",
362 buf, inet_ntoa(ip->ip_dst), icmplen);
363 }
364#endif
365 if (icmplen < ICMP_MINLEN) {
366 ICMPSTAT_INC(icps_tooshort);
367 goto freeit;
368 }
369 i = hlen + min(icmplen, ICMP_ADVLENMIN);
370 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
371 ICMPSTAT_INC(icps_tooshort);
372 return;
373 }
374 ip = mtod(m, struct ip *);
375 m->m_len -= hlen;
376 m->m_data += hlen;
377 icp = mtod(m, struct icmp *);
378 if (in_cksum(m, icmplen)) {
379 ICMPSTAT_INC(icps_checksum);
380 goto freeit;
381 }
382 m->m_len += hlen;
383 m->m_data -= hlen;
384
385 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
386 /*
387 * Deliver very specific ICMP type only.
388 */
389 switch (icp->icmp_type) {
390 case ICMP_UNREACH:
391 case ICMP_TIMXCEED:
392 break;
393 default:
394 goto freeit;
395 }
396 }
397
398#ifdef ICMPPRINTFS
399 if (icmpprintfs)
400 printf("icmp_input, type %d code %d\n", icp->icmp_type,
401 icp->icmp_code);
402#endif
403
404 /*
405 * Message type specific processing.
406 */
407 if (icp->icmp_type > ICMP_MAXTYPE)
408 goto raw;
409
410 /* Initialize */
411 bzero(&icmpsrc, sizeof(icmpsrc));
412 icmpsrc.sin_len = sizeof(struct sockaddr_in);
413 icmpsrc.sin_family = AF_INET;
414 bzero(&icmpdst, sizeof(icmpdst));
415 icmpdst.sin_len = sizeof(struct sockaddr_in);
416 icmpdst.sin_family = AF_INET;
417 bzero(&icmpgw, sizeof(icmpgw));
418 icmpgw.sin_len = sizeof(struct sockaddr_in);
419 icmpgw.sin_family = AF_INET;
420
421 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
422 code = icp->icmp_code;
423 switch (icp->icmp_type) {
424
425 case ICMP_UNREACH:
426 switch (code) {
427 case ICMP_UNREACH_NET:
428 case ICMP_UNREACH_HOST:
429 case ICMP_UNREACH_SRCFAIL:
430 case ICMP_UNREACH_NET_UNKNOWN:
431 case ICMP_UNREACH_HOST_UNKNOWN:
432 case ICMP_UNREACH_ISOLATED:
433 case ICMP_UNREACH_TOSNET:
434 case ICMP_UNREACH_TOSHOST:
435 case ICMP_UNREACH_HOST_PRECEDENCE:
436 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
437 code = PRC_UNREACH_NET;
438 break;
439
440 case ICMP_UNREACH_NEEDFRAG:
441 code = PRC_MSGSIZE;
442 break;
443
444 /*
445 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
446 * Treat subcodes 2,3 as immediate RST
447 */
448 case ICMP_UNREACH_PROTOCOL:
449 case ICMP_UNREACH_PORT:
450 code = PRC_UNREACH_PORT;
451 break;
452
453 case ICMP_UNREACH_NET_PROHIB:
454 case ICMP_UNREACH_HOST_PROHIB:
455 case ICMP_UNREACH_FILTER_PROHIB:
456 code = PRC_UNREACH_ADMIN_PROHIB;
457 break;
458
459 default:
460 goto badcode;
461 }
462 goto deliver;
463
464 case ICMP_TIMXCEED:
465 if (code > 1)
466 goto badcode;
467 code += PRC_TIMXCEED_INTRANS;
468 goto deliver;
469
470 case ICMP_PARAMPROB:
471 if (code > 1)
472 goto badcode;
473 code = PRC_PARAMPROB;
474 goto deliver;
475
476 case ICMP_SOURCEQUENCH:
477 if (code)
478 goto badcode;
479 code = PRC_QUENCH;
480 deliver:
481 /*
482 * Problem with datagram; advise higher level routines.
483 */
484 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
485 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
486 ICMPSTAT_INC(icps_badlen);
487 goto freeit;
488 }
489 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
490 /* Discard ICMP's in response to multicast packets */
491 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
492 goto badcode;
493#ifdef ICMPPRINTFS
494 if (icmpprintfs)
495 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
496#endif
497 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
498 /*
499 * XXX if the packet contains [IPv4 AH TCP], we can't make a
500 * notification to TCP layer.
501 */
502 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
503 if (ctlfunc)
504 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
505 (void *)&icp->icmp_ip);
506 break;
507
508 badcode:
509 ICMPSTAT_INC(icps_badcode);
510 break;
511
512 case ICMP_ECHO:
513 if (!V_icmpbmcastecho
514 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
515 ICMPSTAT_INC(icps_bmcastecho);
516 break;
517 }
518 icp->icmp_type = ICMP_ECHOREPLY;
519 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
520 goto freeit;
521 else
522 goto reflect;
523
524 case ICMP_TSTAMP:
525 if (!V_icmpbmcastecho
526 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
527 ICMPSTAT_INC(icps_bmcasttstamp);
528 break;
529 }
530 if (icmplen < ICMP_TSLEN) {
531 ICMPSTAT_INC(icps_badlen);
532 break;
533 }
534 icp->icmp_type = ICMP_TSTAMPREPLY;
535 icp->icmp_rtime = iptime();
536 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
537 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
538 goto freeit;
539 else
540 goto reflect;
541
542 case ICMP_MASKREQ:
543 if (V_icmpmaskrepl == 0)
544 break;
545 /*
546 * We are not able to respond with all ones broadcast
547 * unless we receive it over a point-to-point interface.
548 */
549 if (icmplen < ICMP_MASKLEN)
550 break;
551 switch (ip->ip_dst.s_addr) {
552
553 case INADDR_BROADCAST:
554 case INADDR_ANY:
555 icmpdst.sin_addr = ip->ip_src;
556 break;
557
558 default:
559 icmpdst.sin_addr = ip->ip_dst;
560 }
561 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
562 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
563 if (ia == NULL)
564 break;
565 if (ia->ia_ifp == NULL) {
566 ifa_free(&ia->ia_ifa);
567 break;
568 }
569 icp->icmp_type = ICMP_MASKREPLY;
570 if (V_icmpmaskfake == 0)
571 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
572 else
573 icp->icmp_mask = V_icmpmaskfake;
574 if (ip->ip_src.s_addr == 0) {
575 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
576 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
577 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
578 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
579 }
580 ifa_free(&ia->ia_ifa);
581reflect:
582 ip->ip_len += hlen; /* since ip_input deducts this */
583 ICMPSTAT_INC(icps_reflect);
584 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
585 icmp_reflect(m);
586 return;
587
588 case ICMP_REDIRECT:
589 if (V_log_redirect) {
590 u_long src, dst, gw;
591
592 src = ntohl(ip->ip_src.s_addr);
593 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
594 gw = ntohl(icp->icmp_gwaddr.s_addr);
595 printf("icmp redirect from %d.%d.%d.%d: "
596 "%d.%d.%d.%d => %d.%d.%d.%d\n",
597 (int)(src >> 24), (int)((src >> 16) & 0xff),
598 (int)((src >> 8) & 0xff), (int)(src & 0xff),
599 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
600 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
601 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
602 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
603 }
604 /*
605 * RFC1812 says we must ignore ICMP redirects if we
606 * are acting as router.
607 */
608 if (V_drop_redirect || V_ipforwarding)
609 break;
610 if (code > 3)
611 goto badcode;
612 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
613 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
614 ICMPSTAT_INC(icps_badlen);
615 break;
616 }
617 /*
618 * Short circuit routing redirects to force
619 * immediate change in the kernel's routing
620 * tables. The message is also handed to anyone
621 * listening on a raw socket (e.g. the routing
622 * daemon for use in updating its tables).
623 */
624 icmpgw.sin_addr = ip->ip_src;
625 icmpdst.sin_addr = icp->icmp_gwaddr;
626#ifdef ICMPPRINTFS
627 if (icmpprintfs) {
628 char buf[4 * sizeof "123"];
629 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
630
631 printf("redirect dst %s to %s\n",
632 buf, inet_ntoa(icp->icmp_gwaddr));
633 }
634#endif
635 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
636 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
637 in_rtredirect((struct sockaddr *)&icmpsrc,
638 (struct sockaddr *)&icmpdst,
639 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
640 (struct sockaddr *)&icmpgw, fibnum);
641 }
642 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
643#ifdef IPSEC
644 key_sa_routechange((struct sockaddr *)&icmpsrc);
645#endif
646 break;
647
648 /*
649 * No kernel processing for the following;
650 * just fall through to send to raw listener.
651 */
652 case ICMP_ECHOREPLY:
653 case ICMP_ROUTERADVERT:
654 case ICMP_ROUTERSOLICIT:
655 case ICMP_TSTAMPREPLY:
656 case ICMP_IREQREPLY:
657 case ICMP_MASKREPLY:
658 default:
659 break;
660 }
661
662raw:
663 rip_input(m, off);
664 return;
665
666freeit:
667 m_freem(m);
668}
669
670/*
671 * Reflect the ip packet back to the source
672 */
673static void
674icmp_reflect(struct mbuf *m)
675{
676 struct ip *ip = mtod(m, struct ip *);
677 struct ifaddr *ifa;
678 struct ifnet *ifp;
679 struct in_ifaddr *ia;
680 struct in_addr t;
681 struct mbuf *opts = 0;
682 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
683
684 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
685 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
686 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
687 m_freem(m); /* Bad return address */
688 ICMPSTAT_INC(icps_badaddr);
689 goto done; /* Ip_output() will check for broadcast */
690 }
691
692 t = ip->ip_dst;
693 ip->ip_dst = ip->ip_src;
694
695 /*
696 * Source selection for ICMP replies:
697 *
698 * If the incoming packet was addressed directly to one of our
699 * own addresses, use dst as the src for the reply.
700 */
701 IN_IFADDR_RLOCK();
702 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
703 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
704 t = IA_SIN(ia)->sin_addr;
705 IN_IFADDR_RUNLOCK();
706 goto match;
707 }
708 }
709 IN_IFADDR_RUNLOCK();
710
711 /*
712 * If the incoming packet was addressed to one of our broadcast
713 * addresses, use the first non-broadcast address which corresponds
714 * to the incoming interface.
715 */
716 ifp = m->m_pkthdr.rcvif;
717 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
718 IF_ADDR_LOCK(ifp);
719 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
720 if (ifa->ifa_addr->sa_family != AF_INET)
721 continue;
722 ia = ifatoia(ifa);
723 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
724 t.s_addr) {
725 t = IA_SIN(ia)->sin_addr;
726 IF_ADDR_UNLOCK(ifp);
727 goto match;
728 }
729 }
730 IF_ADDR_UNLOCK(ifp);
731 }
732 /*
733 * If the packet was transiting through us, use the address of
734 * the interface the packet came through in. If that interface
735 * doesn't have a suitable IP address, the normal selection
736 * criteria apply.
737 */
738 if (V_icmp_rfi && ifp != NULL) {
739 IF_ADDR_LOCK(ifp);
740 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
741 if (ifa->ifa_addr->sa_family != AF_INET)
742 continue;
743 ia = ifatoia(ifa);
744 t = IA_SIN(ia)->sin_addr;
745 IF_ADDR_UNLOCK(ifp);
746 goto match;
747 }
748 IF_ADDR_UNLOCK(ifp);
749 }
750 /*
751 * If the incoming packet was not addressed directly to us, use
752 * designated interface for icmp replies specified by sysctl
753 * net.inet.icmp.reply_src (default not set). Otherwise continue
754 * with normal source selection.
755 */
756 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
757 IF_ADDR_LOCK(ifp);
758 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
759 if (ifa->ifa_addr->sa_family != AF_INET)
760 continue;
761 ia = ifatoia(ifa);
762 t = IA_SIN(ia)->sin_addr;
763 IF_ADDR_UNLOCK(ifp);
764 goto match;
765 }
766 IF_ADDR_UNLOCK(ifp);
767 }
768 /*
769 * If the packet was transiting through us, use the address of
770 * the interface that is the closest to the packet source.
771 * When we don't have a route back to the packet source, stop here
772 * and drop the packet.
773 */
774 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
775 if (ia == NULL) {
776 m_freem(m);
777 ICMPSTAT_INC(icps_noroute);
778 goto done;
779 }
780 t = IA_SIN(ia)->sin_addr;
781 ifa_free(&ia->ia_ifa);
782match:
783#ifdef MAC
784 mac_netinet_icmp_replyinplace(m);
785#endif
786 ip->ip_src = t;
787 ip->ip_ttl = V_ip_defttl;
788
789 if (optlen > 0) {
790 register u_char *cp;
791 int opt, cnt;
792 u_int len;
793
794 /*
795 * Retrieve any source routing from the incoming packet;
796 * add on any record-route or timestamp options.
797 */
798 cp = (u_char *) (ip + 1);
799 if ((opts = ip_srcroute(m)) == 0 &&
800 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
801 opts->m_len = sizeof(struct in_addr);
802 mtod(opts, struct in_addr *)->s_addr = 0;
803 }
804 if (opts) {
805#ifdef ICMPPRINTFS
806 if (icmpprintfs)
807 printf("icmp_reflect optlen %d rt %d => ",
808 optlen, opts->m_len);
809#endif
810 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
811 opt = cp[IPOPT_OPTVAL];
812 if (opt == IPOPT_EOL)
813 break;
814 if (opt == IPOPT_NOP)
815 len = 1;
816 else {
817 if (cnt < IPOPT_OLEN + sizeof(*cp))
818 break;
819 len = cp[IPOPT_OLEN];
820 if (len < IPOPT_OLEN + sizeof(*cp) ||
821 len > cnt)
822 break;
823 }
824 /*
825 * Should check for overflow, but it "can't happen"
826 */
827 if (opt == IPOPT_RR || opt == IPOPT_TS ||
828 opt == IPOPT_SECURITY) {
829 bcopy((caddr_t)cp,
830 mtod(opts, caddr_t) + opts->m_len, len);
831 opts->m_len += len;
832 }
833 }
834 /* Terminate & pad, if necessary */
835 cnt = opts->m_len % 4;
836 if (cnt) {
837 for (; cnt < 4; cnt++) {
838 *(mtod(opts, caddr_t) + opts->m_len) =
839 IPOPT_EOL;
840 opts->m_len++;
841 }
842 }
843#ifdef ICMPPRINTFS
844 if (icmpprintfs)
845 printf("%d\n", opts->m_len);
846#endif
847 }
848 /*
849 * Now strip out original options by copying rest of first
850 * mbuf's data back, and adjust the IP length.
851 */
852 ip->ip_len -= optlen;
853 ip->ip_v = IPVERSION;
854 ip->ip_hl = 5;
855 m->m_len -= optlen;
856 if (m->m_flags & M_PKTHDR)
857 m->m_pkthdr.len -= optlen;
858 optlen += sizeof(struct ip);
859 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
860 (unsigned)(m->m_len - sizeof(struct ip)));
861 }
862 m_tag_delete_nonpersistent(m);
863 m->m_flags &= ~(M_BCAST|M_MCAST);
864 icmp_send(m, opts);
865done:
866 if (opts)
867 (void)m_free(opts);
868}
869
870/*
871 * Send an icmp packet back to the ip level,
872 * after supplying a checksum.
873 */
874static void
875icmp_send(struct mbuf *m, struct mbuf *opts)
876{
877 register struct ip *ip = mtod(m, struct ip *);
878 register int hlen;
879 register struct icmp *icp;
880
881 hlen = ip->ip_hl << 2;
882 m->m_data += hlen;
883 m->m_len -= hlen;
884 icp = mtod(m, struct icmp *);
885 icp->icmp_cksum = 0;
886 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
887 m->m_data -= hlen;
888 m->m_len += hlen;
889 m->m_pkthdr.rcvif = (struct ifnet *)0;
890#ifdef ICMPPRINTFS
891 if (icmpprintfs) {
892 char buf[4 * sizeof "123"];
893 strcpy(buf, inet_ntoa(ip->ip_dst));
894 printf("icmp_send dst %s src %s\n",
895 buf, inet_ntoa(ip->ip_src));
896 }
897#endif
898 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
899}
900
901/*
902 * Return milliseconds since 00:00 GMT in network format.
903 */
904uint32_t
905iptime(void)
906{
907 struct timeval atv;
908 u_long t;
909
910 getmicrotime(&atv);
911 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
912 return (htonl(t));
913}
914
915/*
916 * Return the next larger or smaller MTU plateau (table from RFC 1191)
917 * given current value MTU. If DIR is less than zero, a larger plateau
918 * is returned; otherwise, a smaller value is returned.
919 */
920int
921ip_next_mtu(int mtu, int dir)
922{
923 static int mtutab[] = {
924 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
925 296, 68, 0
926 };
927 int i, size;
928
929 size = (sizeof mtutab) / (sizeof mtutab[0]);
930 if (dir >= 0) {
931 for (i = 0; i < size; i++)
932 if (mtu > mtutab[i])
933 return mtutab[i];
934 } else {
935 for (i = size - 1; i >= 0; i--)
936 if (mtu < mtutab[i])
937 return mtutab[i];
938 if (mtu == mtutab[0])
939 return mtutab[0];
940 }
941 return 0;
942}
943
944
945/*
946 * badport_bandlim() - check for ICMP bandwidth limit
947 *
948 * Return 0 if it is ok to send an ICMP error response, -1 if we have
949 * hit our bandwidth limit and it is not ok.
950 *
951 * If icmplim is <= 0, the feature is disabled and 0 is returned.
952 *
953 * For now we separate the TCP and UDP subsystems w/ different 'which'
954 * values. We may eventually remove this separation (and simplify the
955 * code further).
956 *
957 * Note that the printing of the error message is delayed so we can
958 * properly print the icmp error rate that the system was trying to do
959 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
960 * the 'final' error, but it doesn't make sense to solve the printing
961 * delay with more complex code.
962 */
963
964int
965badport_bandlim(int which)
966{
967
968#define N(a) (sizeof (a) / sizeof (a[0]))
969 static struct rate {
970 const char *type;
971 struct timeval lasttime;
972 int curpps;
973 } rates[BANDLIM_MAX+1] = {
974 { "icmp unreach response" },
975 { "icmp ping response" },
976 { "icmp tstamp response" },
977 { "closed port RST response" },
978 { "open port RST response" },
979 { "icmp6 unreach response" }
980 };
981
982 /*
983 * Return ok status if feature disabled or argument out of range.
984 */
985 if (V_icmplim > 0 && (u_int) which < N(rates)) {
986 struct rate *r = &rates[which];
987 int opps = r->curpps;
988
989 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
990 return -1; /* discard packet */
991 /*
992 * If we've dropped below the threshold after having
993 * rate-limited traffic print the message. This preserves
994 * the previous behaviour at the expense of added complexity.
995 */
996 if (V_icmplim_output && opps > V_icmplim)
997 printf("Limiting %s from %d to %d packets/sec\n",
998 r->type, opps, V_icmplim);
999 }
1000 return 0; /* okay to send packet */
1001#undef N
1002}