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/7.4/sys/netinet/ip_icmp.c 211543 2010-08-21 11:02:18Z andre $");
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 #include <sys/syslog.h>
47
48 #include <net/if.h>
49 #include <net/if_types.h>
50 #include <net/route.h>
51
52 #include <netinet/in.h>
53 #include <netinet/in_pcb.h>
54 #include <netinet/in_systm.h>
55 #include <netinet/in_var.h>
56 #include <netinet/ip.h>
57 #include <netinet/ip_icmp.h>
58 #include <netinet/ip_var.h>
59 #include <netinet/ip_options.h>
60 #include <netinet/tcp.h>
61 #include <netinet/tcp_var.h>
62 #include <netinet/tcpip.h>
63 #include <netinet/icmp_var.h>
64
65 #ifdef IPSEC
66 #include <netipsec/ipsec.h>
67 #include <netipsec/key.h>
68 #endif
69
70 #include <machine/in_cksum.h>
71
72 #include <security/mac/mac_framework.h>
73
74 /*
75 * ICMP routines: error generation, receive packet processing, and
76 * routines to turnaround packets back to the originator, and
77 * host table maintenance routines.
78 */
79
80 struct icmpstat icmpstat;
81 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
82 &icmpstat, icmpstat, "");
83
84 static int icmpmaskrepl = 0;
85 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
86 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets.");
87
88 static u_int icmpmaskfake = 0;
89 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
90 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets.");
91
92 static int drop_redirect = 0;
93 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
94 &drop_redirect, 0, "Ignore ICMP redirects");
95
96 static int log_redirect = 0;
97 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
98 &log_redirect, 0, "Log ICMP redirects to the console");
99
100 static int icmplim = 200;
101 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
102 &icmplim, 0, "Maximum number of ICMP responses per second");
103
104 static int icmplim_output = 1;
105 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
106 &icmplim_output, 0, "Enable rate limiting of ICMP responses");
107
108 static char reply_src[IFNAMSIZ];
109 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
110 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets.");
111
112 static int icmp_rfi = 0;
113 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
114 &icmp_rfi, 0, "ICMP reply from incoming interface for "
115 "non-local packets");
116
117 static int icmp_quotelen = 8;
118 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
119 &icmp_quotelen, 0, "Number of bytes from original packet to "
120 "quote in ICMP reply");
121
122 /*
123 * ICMP broadcast echo sysctl
124 */
125
126 static int icmpbmcastecho = 0;
127 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
128 &icmpbmcastecho, 0, "");
129
130
131 #ifdef ICMPPRINTFS
132 int icmpprintfs = 0;
133 #endif
134
135 static void icmp_reflect(struct mbuf *);
136 static void icmp_send(struct mbuf *, struct mbuf *);
137
138 extern struct protosw inetsw[];
139
140 /*
141 * Generate an error packet of type error
142 * in response to bad packet ip.
143 */
144 void
145 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
146 {
147 register struct ip *oip = mtod(n, struct ip *), *nip;
148 register unsigned oiphlen = oip->ip_hl << 2;
149 register struct icmp *icp;
150 register struct mbuf *m;
151 unsigned icmplen, icmpelen, nlen;
152
153 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
154 #ifdef ICMPPRINTFS
155 if (icmpprintfs)
156 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
157 #endif
158 if (type != ICMP_REDIRECT)
159 icmpstat.icps_error++;
160 /*
161 * Don't send error:
162 * if the original packet was encrypted.
163 * if not the first fragment of message.
164 * in response to a multicast or broadcast packet.
165 * if the old packet protocol was an ICMP error message.
166 */
167 if (n->m_flags & M_DECRYPTED)
168 goto freeit;
169 if (oip->ip_off & ~(IP_MF|IP_DF))
170 goto freeit;
171 if (n->m_flags & (M_BCAST|M_MCAST))
172 goto freeit;
173 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
174 n->m_len >= oiphlen + ICMP_MINLEN &&
175 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
176 icmpstat.icps_oldicmp++;
177 goto freeit;
178 }
179 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
180 if (oiphlen + 8 > n->m_len)
181 goto freeit;
182 /*
183 * Calculate length to quote from original packet and
184 * prevent the ICMP mbuf from overflowing.
185 * Unfortunatly this is non-trivial since ip_forward()
186 * sends us truncated packets.
187 */
188 nlen = m_length(n, NULL);
189 if (oip->ip_p == IPPROTO_TCP) {
190 struct tcphdr *th;
191 int tcphlen;
192
193 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
194 n->m_next == NULL)
195 goto stdreply;
196 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
197 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
198 goto freeit;
199 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
200 tcphlen = th->th_off << 2;
201 if (tcphlen < sizeof(struct tcphdr))
202 goto freeit;
203 if (oip->ip_len < oiphlen + tcphlen)
204 goto freeit;
205 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
206 goto stdreply;
207 if (n->m_len < oiphlen + tcphlen &&
208 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
209 goto freeit;
210 icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen));
211 } else
212 stdreply: icmpelen = max(8, min(icmp_quotelen, oip->ip_len - oiphlen));
213
214 icmplen = min(oiphlen + icmpelen, nlen);
215 if (icmplen < sizeof(struct ip))
216 goto freeit;
217
218 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
219 m = m_gethdr(M_DONTWAIT, MT_DATA);
220 else
221 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
222 if (m == NULL)
223 goto freeit;
224 #ifdef MAC
225 mac_create_mbuf_netlayer(n, m);
226 #endif
227 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
228 m_align(m, ICMP_MINLEN + icmplen);
229 m->m_len = ICMP_MINLEN + icmplen;
230
231 /* XXX MRT make the outgoing packet use the same FIB
232 * that was associated with the incoming packet
233 */
234 M_SETFIB(m, M_GETFIB(n));
235 icp = mtod(m, struct icmp *);
236 icmpstat.icps_outhist[type]++;
237 icp->icmp_type = type;
238 if (type == ICMP_REDIRECT)
239 icp->icmp_gwaddr.s_addr = dest;
240 else {
241 icp->icmp_void = 0;
242 /*
243 * The following assignments assume an overlay with the
244 * just zeroed icmp_void field.
245 */
246 if (type == ICMP_PARAMPROB) {
247 icp->icmp_pptr = code;
248 code = 0;
249 } else if (type == ICMP_UNREACH &&
250 code == ICMP_UNREACH_NEEDFRAG && mtu) {
251 icp->icmp_nextmtu = htons(mtu);
252 }
253 }
254 icp->icmp_code = code;
255
256 /*
257 * Copy the quotation into ICMP message and
258 * convert quoted IP header back to network representation.
259 */
260 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
261 nip = &icp->icmp_ip;
262 nip->ip_len = htons(nip->ip_len);
263 nip->ip_off = htons(nip->ip_off);
264
265 /*
266 * Set up ICMP message mbuf and copy old IP header (without options
267 * in front of ICMP message.
268 * If the original mbuf was meant to bypass the firewall, the error
269 * reply should bypass as well.
270 */
271 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
272 m->m_data -= sizeof(struct ip);
273 m->m_len += sizeof(struct ip);
274 m->m_pkthdr.len = m->m_len;
275 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
276 nip = mtod(m, struct ip *);
277 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
278 nip->ip_len = m->m_len;
279 nip->ip_v = IPVERSION;
280 nip->ip_hl = 5;
281 nip->ip_p = IPPROTO_ICMP;
282 nip->ip_tos = 0;
283 icmp_reflect(m);
284
285 freeit:
286 m_freem(n);
287 }
288
289 /*
290 * Process a received ICMP message.
291 */
292 void
293 icmp_input(struct mbuf *m, int off)
294 {
295 struct icmp *icp;
296 struct in_ifaddr *ia;
297 struct ip *ip = mtod(m, struct ip *);
298 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
299 int hlen = off;
300 int icmplen = ip->ip_len;
301 int i, code;
302 void (*ctlfunc)(int, struct sockaddr *, void *);
303 int fibnum;
304
305 /*
306 * Locate icmp structure in mbuf, and check
307 * that not corrupted and of at least minimum length.
308 */
309 #ifdef ICMPPRINTFS
310 if (icmpprintfs) {
311 char buf[4 * sizeof "123"];
312 strcpy(buf, inet_ntoa(ip->ip_src));
313 printf("icmp_input from %s to %s, len %d\n",
314 buf, inet_ntoa(ip->ip_dst), icmplen);
315 }
316 #endif
317 if (icmplen < ICMP_MINLEN) {
318 icmpstat.icps_tooshort++;
319 goto freeit;
320 }
321 i = hlen + min(icmplen, ICMP_ADVLENMIN);
322 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
323 icmpstat.icps_tooshort++;
324 return;
325 }
326 ip = mtod(m, struct ip *);
327 m->m_len -= hlen;
328 m->m_data += hlen;
329 icp = mtod(m, struct icmp *);
330 if (in_cksum(m, icmplen)) {
331 icmpstat.icps_checksum++;
332 goto freeit;
333 }
334 m->m_len += hlen;
335 m->m_data -= hlen;
336
337 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
338 /*
339 * Deliver very specific ICMP type only.
340 */
341 switch (icp->icmp_type) {
342 case ICMP_UNREACH:
343 case ICMP_TIMXCEED:
344 break;
345 default:
346 goto freeit;
347 }
348 }
349
350 #ifdef ICMPPRINTFS
351 if (icmpprintfs)
352 printf("icmp_input, type %d code %d\n", icp->icmp_type,
353 icp->icmp_code);
354 #endif
355
356 /*
357 * Message type specific processing.
358 */
359 if (icp->icmp_type > ICMP_MAXTYPE)
360 goto raw;
361
362 /* Initialize */
363 bzero(&icmpsrc, sizeof(icmpsrc));
364 icmpsrc.sin_len = sizeof(struct sockaddr_in);
365 icmpsrc.sin_family = AF_INET;
366 bzero(&icmpdst, sizeof(icmpdst));
367 icmpdst.sin_len = sizeof(struct sockaddr_in);
368 icmpdst.sin_family = AF_INET;
369 bzero(&icmpgw, sizeof(icmpgw));
370 icmpgw.sin_len = sizeof(struct sockaddr_in);
371 icmpgw.sin_family = AF_INET;
372
373 icmpstat.icps_inhist[icp->icmp_type]++;
374 code = icp->icmp_code;
375 switch (icp->icmp_type) {
376
377 case ICMP_UNREACH:
378 switch (code) {
379 case ICMP_UNREACH_NET:
380 case ICMP_UNREACH_HOST:
381 case ICMP_UNREACH_SRCFAIL:
382 case ICMP_UNREACH_NET_UNKNOWN:
383 case ICMP_UNREACH_HOST_UNKNOWN:
384 case ICMP_UNREACH_ISOLATED:
385 case ICMP_UNREACH_TOSNET:
386 case ICMP_UNREACH_TOSHOST:
387 case ICMP_UNREACH_HOST_PRECEDENCE:
388 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
389 code = PRC_UNREACH_NET;
390 break;
391
392 case ICMP_UNREACH_NEEDFRAG:
393 code = PRC_MSGSIZE;
394 break;
395
396 /*
397 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
398 * Treat subcodes 2,3 as immediate RST
399 */
400 case ICMP_UNREACH_PROTOCOL:
401 case ICMP_UNREACH_PORT:
402 code = PRC_UNREACH_PORT;
403 break;
404
405 case ICMP_UNREACH_NET_PROHIB:
406 case ICMP_UNREACH_HOST_PROHIB:
407 case ICMP_UNREACH_FILTER_PROHIB:
408 code = PRC_UNREACH_ADMIN_PROHIB;
409 break;
410
411 default:
412 goto badcode;
413 }
414 goto deliver;
415
416 case ICMP_TIMXCEED:
417 if (code > 1)
418 goto badcode;
419 code += PRC_TIMXCEED_INTRANS;
420 goto deliver;
421
422 case ICMP_PARAMPROB:
423 if (code > 1)
424 goto badcode;
425 code = PRC_PARAMPROB;
426 goto deliver;
427
428 case ICMP_SOURCEQUENCH:
429 if (code)
430 goto badcode;
431 code = PRC_QUENCH;
432 deliver:
433 /*
434 * Problem with datagram; advise higher level routines.
435 */
436 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
437 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
438 icmpstat.icps_badlen++;
439 goto freeit;
440 }
441 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
442 /* Discard ICMP's in response to multicast packets */
443 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
444 goto badcode;
445 #ifdef ICMPPRINTFS
446 if (icmpprintfs)
447 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
448 #endif
449 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
450 /*
451 * XXX if the packet contains [IPv4 AH TCP], we can't make a
452 * notification to TCP layer.
453 */
454 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
455 if (ctlfunc)
456 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
457 (void *)&icp->icmp_ip);
458 break;
459
460 badcode:
461 icmpstat.icps_badcode++;
462 break;
463
464 case ICMP_ECHO:
465 if (!icmpbmcastecho
466 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
467 icmpstat.icps_bmcastecho++;
468 break;
469 }
470 icp->icmp_type = ICMP_ECHOREPLY;
471 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
472 goto freeit;
473 else
474 goto reflect;
475
476 case ICMP_TSTAMP:
477 if (!icmpbmcastecho
478 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
479 icmpstat.icps_bmcasttstamp++;
480 break;
481 }
482 if (icmplen < ICMP_TSLEN) {
483 icmpstat.icps_badlen++;
484 break;
485 }
486 icp->icmp_type = ICMP_TSTAMPREPLY;
487 icp->icmp_rtime = iptime();
488 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
489 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
490 goto freeit;
491 else
492 goto reflect;
493
494 case ICMP_MASKREQ:
495 if (icmpmaskrepl == 0)
496 break;
497 /*
498 * We are not able to respond with all ones broadcast
499 * unless we receive it over a point-to-point interface.
500 */
501 if (icmplen < ICMP_MASKLEN)
502 break;
503 switch (ip->ip_dst.s_addr) {
504
505 case INADDR_BROADCAST:
506 case INADDR_ANY:
507 icmpdst.sin_addr = ip->ip_src;
508 break;
509
510 default:
511 icmpdst.sin_addr = ip->ip_dst;
512 }
513 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
514 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
515 if (ia == 0)
516 break;
517 if (ia->ia_ifp == 0)
518 break;
519 icp->icmp_type = ICMP_MASKREPLY;
520 if (icmpmaskfake == 0)
521 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
522 else
523 icp->icmp_mask = icmpmaskfake;
524 if (ip->ip_src.s_addr == 0) {
525 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
526 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
527 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
528 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
529 }
530 reflect:
531 ip->ip_len += hlen; /* since ip_input deducts this */
532 icmpstat.icps_reflect++;
533 icmpstat.icps_outhist[icp->icmp_type]++;
534 icmp_reflect(m);
535 return;
536
537 case ICMP_REDIRECT:
538 if (log_redirect) {
539 u_long src, dst, gw;
540
541 src = ntohl(ip->ip_src.s_addr);
542 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
543 gw = ntohl(icp->icmp_gwaddr.s_addr);
544 printf("icmp redirect from %d.%d.%d.%d: "
545 "%d.%d.%d.%d => %d.%d.%d.%d\n",
546 (int)(src >> 24), (int)((src >> 16) & 0xff),
547 (int)((src >> 8) & 0xff), (int)(src & 0xff),
548 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
549 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
550 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
551 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
552 }
553 /*
554 * RFC1812 says we must ignore ICMP redirects if we
555 * are acting as router.
556 */
557 if (drop_redirect || ipforwarding)
558 break;
559 if (code > 3)
560 goto badcode;
561 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
562 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
563 icmpstat.icps_badlen++;
564 break;
565 }
566 /*
567 * Short circuit routing redirects to force
568 * immediate change in the kernel's routing
569 * tables. The message is also handed to anyone
570 * listening on a raw socket (e.g. the routing
571 * daemon for use in updating its tables).
572 */
573 icmpgw.sin_addr = ip->ip_src;
574 icmpdst.sin_addr = icp->icmp_gwaddr;
575 #ifdef ICMPPRINTFS
576 if (icmpprintfs) {
577 char buf[4 * sizeof "123"];
578 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
579
580 printf("redirect dst %s to %s\n",
581 buf, inet_ntoa(icp->icmp_gwaddr));
582 }
583 #endif
584 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
585 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
586 in_rtredirect((struct sockaddr *)&icmpsrc,
587 (struct sockaddr *)&icmpdst,
588 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
589 (struct sockaddr *)&icmpgw, fibnum);
590 }
591 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
592 #ifdef IPSEC
593 key_sa_routechange((struct sockaddr *)&icmpsrc);
594 #endif
595 break;
596
597 /*
598 * No kernel processing for the following;
599 * just fall through to send to raw listener.
600 */
601 case ICMP_ECHOREPLY:
602 case ICMP_ROUTERADVERT:
603 case ICMP_ROUTERSOLICIT:
604 case ICMP_TSTAMPREPLY:
605 case ICMP_IREQREPLY:
606 case ICMP_MASKREPLY:
607 default:
608 break;
609 }
610
611 raw:
612 rip_input(m, off);
613 return;
614
615 freeit:
616 m_freem(m);
617 }
618
619 /*
620 * Reflect the ip packet back to the source
621 */
622 static void
623 icmp_reflect(struct mbuf *m)
624 {
625 struct ip *ip = mtod(m, struct ip *);
626 struct ifaddr *ifa;
627 struct ifnet *ifn;
628 struct in_ifaddr *ia;
629 struct in_addr t;
630 struct mbuf *opts = 0;
631 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
632
633 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
634 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
635 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
636 m_freem(m); /* Bad return address */
637 icmpstat.icps_badaddr++;
638 goto done; /* Ip_output() will check for broadcast */
639 }
640
641 t = ip->ip_dst;
642 ip->ip_dst = ip->ip_src;
643
644 /*
645 * Source selection for ICMP replies:
646 *
647 * If the incoming packet was addressed directly to one of our
648 * own addresses, use dst as the src for the reply.
649 */
650 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
651 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
652 goto match;
653 /*
654 * If the incoming packet was addressed to one of our broadcast
655 * addresses, use the first non-broadcast address which corresponds
656 * to the incoming interface.
657 */
658 if (m->m_pkthdr.rcvif != NULL &&
659 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
660 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
661 if (ifa->ifa_addr->sa_family != AF_INET)
662 continue;
663 ia = ifatoia(ifa);
664 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
665 t.s_addr)
666 goto match;
667 }
668 }
669 /*
670 * If the packet was transiting through us, use the address of
671 * the interface the packet came through in. If that interface
672 * doesn't have a suitable IP address, the normal selection
673 * criteria apply.
674 */
675 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) {
676 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
677 if (ifa->ifa_addr->sa_family != AF_INET)
678 continue;
679 ia = ifatoia(ifa);
680 goto match;
681 }
682 }
683 /*
684 * If the incoming packet was not addressed directly to us, use
685 * designated interface for icmp replies specified by sysctl
686 * net.inet.icmp.reply_src (default not set). Otherwise continue
687 * with normal source selection.
688 */
689 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) {
690 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) {
691 if (ifa->ifa_addr->sa_family != AF_INET)
692 continue;
693 ia = ifatoia(ifa);
694 goto match;
695 }
696 }
697 /*
698 * If the packet was transiting through us, use the address of
699 * the interface that is the closest to the packet source.
700 * When we don't have a route back to the packet source, stop here
701 * and drop the packet.
702 */
703 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
704 if (ia == NULL) {
705 m_freem(m);
706 icmpstat.icps_noroute++;
707 goto done;
708 }
709 match:
710 #ifdef MAC
711 mac_reflect_mbuf_icmp(m);
712 #endif
713 t = IA_SIN(ia)->sin_addr;
714 ip->ip_src = t;
715 ip->ip_ttl = ip_defttl;
716
717 if (optlen > 0) {
718 register u_char *cp;
719 int opt, cnt;
720 u_int len;
721
722 /*
723 * Retrieve any source routing from the incoming packet;
724 * add on any record-route or timestamp options.
725 */
726 cp = (u_char *) (ip + 1);
727 if ((opts = ip_srcroute(m)) == 0 &&
728 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
729 opts->m_len = sizeof(struct in_addr);
730 mtod(opts, struct in_addr *)->s_addr = 0;
731 }
732 if (opts) {
733 #ifdef ICMPPRINTFS
734 if (icmpprintfs)
735 printf("icmp_reflect optlen %d rt %d => ",
736 optlen, opts->m_len);
737 #endif
738 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
739 opt = cp[IPOPT_OPTVAL];
740 if (opt == IPOPT_EOL)
741 break;
742 if (opt == IPOPT_NOP)
743 len = 1;
744 else {
745 if (cnt < IPOPT_OLEN + sizeof(*cp))
746 break;
747 len = cp[IPOPT_OLEN];
748 if (len < IPOPT_OLEN + sizeof(*cp) ||
749 len > cnt)
750 break;
751 }
752 /*
753 * Should check for overflow, but it "can't happen"
754 */
755 if (opt == IPOPT_RR || opt == IPOPT_TS ||
756 opt == IPOPT_SECURITY) {
757 bcopy((caddr_t)cp,
758 mtod(opts, caddr_t) + opts->m_len, len);
759 opts->m_len += len;
760 }
761 }
762 /* Terminate & pad, if necessary */
763 cnt = opts->m_len % 4;
764 if (cnt) {
765 for (; cnt < 4; cnt++) {
766 *(mtod(opts, caddr_t) + opts->m_len) =
767 IPOPT_EOL;
768 opts->m_len++;
769 }
770 }
771 #ifdef ICMPPRINTFS
772 if (icmpprintfs)
773 printf("%d\n", opts->m_len);
774 #endif
775 }
776 /*
777 * Now strip out original options by copying rest of first
778 * mbuf's data back, and adjust the IP length.
779 */
780 ip->ip_len -= optlen;
781 ip->ip_v = IPVERSION;
782 ip->ip_hl = 5;
783 m->m_len -= optlen;
784 if (m->m_flags & M_PKTHDR)
785 m->m_pkthdr.len -= optlen;
786 optlen += sizeof(struct ip);
787 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
788 (unsigned)(m->m_len - sizeof(struct ip)));
789 }
790 m_tag_delete_nonpersistent(m);
791 m->m_flags &= ~(M_BCAST|M_MCAST);
792 icmp_send(m, opts);
793 done:
794 if (opts)
795 (void)m_free(opts);
796 }
797
798 /*
799 * Send an icmp packet back to the ip level,
800 * after supplying a checksum.
801 */
802 static void
803 icmp_send(struct mbuf *m, struct mbuf *opts)
804 {
805 register struct ip *ip = mtod(m, struct ip *);
806 register int hlen;
807 register struct icmp *icp;
808
809 hlen = ip->ip_hl << 2;
810 m->m_data += hlen;
811 m->m_len -= hlen;
812 icp = mtod(m, struct icmp *);
813 icp->icmp_cksum = 0;
814 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
815 m->m_data -= hlen;
816 m->m_len += hlen;
817 m->m_pkthdr.rcvif = (struct ifnet *)0;
818 #ifdef ICMPPRINTFS
819 if (icmpprintfs) {
820 char buf[4 * sizeof "123"];
821 strcpy(buf, inet_ntoa(ip->ip_dst));
822 printf("icmp_send dst %s src %s\n",
823 buf, inet_ntoa(ip->ip_src));
824 }
825 #endif
826 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
827 }
828
829 /*
830 * Return milliseconds since 00:00 GMT in network format.
831 */
832 uint32_t
833 iptime(void)
834 {
835 struct timeval atv;
836 u_long t;
837
838 getmicrotime(&atv);
839 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
840 return (htonl(t));
841 }
842
843 /*
844 * Return the next larger or smaller MTU plateau (table from RFC 1191)
845 * given current value MTU. If DIR is less than zero, a larger plateau
846 * is returned; otherwise, a smaller value is returned.
847 */
848 int
849 ip_next_mtu(int mtu, int dir)
850 {
851 static int mtutab[] = {
852 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
853 296, 68, 0
854 };
855 int i, size;
856
857 size = (sizeof mtutab) / (sizeof mtutab[0]);
858 if (dir >= 0) {
859 for (i = 0; i < size; i++)
860 if (mtu > mtutab[i])
861 return mtutab[i];
862 } else {
863 for (i = size - 1; i >= 0; i--)
864 if (mtu < mtutab[i])
865 return mtutab[i];
866 if (mtu == mtutab[0])
867 return mtutab[0];
868 }
869 return 0;
870 }
871
872
873 /*
874 * badport_bandlim() - check for ICMP bandwidth limit
875 *
876 * Return 0 if it is ok to send an ICMP error response, -1 if we have
877 * hit our bandwidth limit and it is not ok.
878 *
879 * If icmplim is <= 0, the feature is disabled and 0 is returned.
880 *
881 * For now we separate the TCP and UDP subsystems w/ different 'which'
882 * values. We may eventually remove this separation (and simplify the
883 * code further).
884 *
885 * Note that the printing of the error message is delayed so we can
886 * properly print the icmp error rate that the system was trying to do
887 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
888 * the 'final' error, but it doesn't make sense to solve the printing
889 * delay with more complex code.
890 */
891
892 int
893 badport_bandlim(int which)
894 {
895 #define N(a) (sizeof (a) / sizeof (a[0]))
896 static struct rate {
897 const char *type;
898 struct timeval lasttime;
899 int curpps;
900 } rates[BANDLIM_MAX+1] = {
901 { "icmp unreach response" },
902 { "icmp ping response" },
903 { "icmp tstamp response" },
904 { "closed port RST response" },
905 { "open port RST response" },
906 { "icmp6 unreach response" }
907 };
908
909 /*
910 * Return ok status if feature disabled or argument out of range.
911 */
912 if (icmplim > 0 && (u_int) which < N(rates)) {
913 struct rate *r = &rates[which];
914 int opps = r->curpps;
915
916 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim))
917 return -1; /* discard packet */
918 /*
919 * If we've dropped below the threshold after having
920 * rate-limited traffic print the message. This preserves
921 * the previous behaviour at the expense of added complexity.
922 */
923 if (icmplim_output && opps > icmplim)
924 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
925 r->type, opps, icmplim);
926 }
927 return 0; /* okay to send packet */
928 #undef N
929 }
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