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: src/sys/netinet/ip_icmp.c,v 1.126 2008/10/02 15:37:58 zec Exp $");
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/vimage.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_V_STRUCT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_STATS, stats,
82 CTLFLAG_RW, icmpstat, icmpstat, "");
83
84 static int icmpmaskrepl = 0;
85 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_MASKREPL, maskrepl,
86 CTLFLAG_RW, icmpmaskrepl, 0,
87 "Reply to ICMP Address Mask Request packets.");
88
89 static u_int icmpmaskfake = 0;
90 SYSCTL_V_UINT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
91 icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets.");
92
93 static int drop_redirect = 0;
94 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, drop_redirect,
95 CTLFLAG_RW, drop_redirect, 0, "Ignore ICMP redirects");
96
97 static int log_redirect = 0;
98 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, log_redirect,
99 CTLFLAG_RW, log_redirect, 0, "Log ICMP redirects to the console");
100
101 static int icmplim = 200;
102 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, ICMPCTL_ICMPLIM, icmplim,
103 CTLFLAG_RW, icmplim, 0, "Maximum number of ICMP responses per second");
104
105 static int icmplim_output = 1;
106 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, icmplim_output,
107 CTLFLAG_RW, icmplim_output, 0,
108 "Enable rate limiting of ICMP responses");
109
110 static char reply_src[IFNAMSIZ];
111 SYSCTL_V_STRING(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, reply_src,
112 CTLFLAG_RW, reply_src, IFNAMSIZ,
113 "icmp reply source for non-local packets.");
114
115 static int icmp_rfi = 0;
116 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, reply_from_interface,
117 CTLFLAG_RW, icmp_rfi, 0, "ICMP reply from incoming interface for "
118 "non-local packets");
119
120 static int icmp_quotelen = 8;
121 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
122 icmp_quotelen, 0, "Number of bytes from original packet to "
123 "quote in ICMP reply");
124
125 /*
126 * ICMP broadcast echo sysctl
127 */
128
129 static int icmpbmcastecho = 0;
130 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_icmp, OID_AUTO, bmcastecho,
131 CTLFLAG_RW, icmpbmcastecho, 0, "");
132
133
134 #ifdef ICMPPRINTFS
135 int icmpprintfs = 0;
136 #endif
137
138 static void icmp_reflect(struct mbuf *);
139 static void icmp_send(struct mbuf *, struct mbuf *);
140
141 extern struct protosw inetsw[];
142
143 /*
144 * Generate an error packet of type error
145 * in response to bad packet ip.
146 */
147 void
148 icmp_error(struct mbuf *n, int type, int code, n_long dest, int mtu)
149 {
150 INIT_VNET_INET(curvnet);
151 register struct ip *oip = mtod(n, struct ip *), *nip;
152 register unsigned oiphlen = oip->ip_hl << 2;
153 register struct icmp *icp;
154 register struct mbuf *m;
155 unsigned icmplen, icmpelen, nlen;
156
157 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
158 #ifdef ICMPPRINTFS
159 if (icmpprintfs)
160 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
161 #endif
162 if (type != ICMP_REDIRECT)
163 V_icmpstat.icps_error++;
164 /*
165 * Don't send error:
166 * if the original packet was encrypted.
167 * if not the first fragment of message.
168 * in response to a multicast or broadcast packet.
169 * if the old packet protocol was an ICMP error message.
170 */
171 if (n->m_flags & M_DECRYPTED)
172 goto freeit;
173 if (oip->ip_off & ~(IP_MF|IP_DF))
174 goto freeit;
175 if (n->m_flags & (M_BCAST|M_MCAST))
176 goto freeit;
177 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
178 n->m_len >= oiphlen + ICMP_MINLEN &&
179 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
180 V_icmpstat.icps_oldicmp++;
181 goto freeit;
182 }
183 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
184 if (oiphlen + 8 > n->m_len)
185 goto freeit;
186 /*
187 * Calculate length to quote from original packet and
188 * prevent the ICMP mbuf from overflowing.
189 * Unfortunatly this is non-trivial since ip_forward()
190 * sends us truncated packets.
191 */
192 nlen = m_length(n, NULL);
193 if (oip->ip_p == IPPROTO_TCP) {
194 struct tcphdr *th;
195 int tcphlen;
196
197 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
198 n->m_next == NULL)
199 goto stdreply;
200 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
201 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
202 goto freeit;
203 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
204 tcphlen = th->th_off << 2;
205 if (tcphlen < sizeof(struct tcphdr))
206 goto freeit;
207 if (oip->ip_len < oiphlen + tcphlen)
208 goto freeit;
209 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
210 goto stdreply;
211 if (n->m_len < oiphlen + tcphlen &&
212 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
213 goto freeit;
214 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen));
215 } else
216 stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen));
217
218 icmplen = min(oiphlen + icmpelen, nlen);
219 if (icmplen < sizeof(struct ip))
220 goto freeit;
221
222 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
223 m = m_gethdr(M_DONTWAIT, MT_DATA);
224 else
225 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
226 if (m == NULL)
227 goto freeit;
228 #ifdef MAC
229 mac_netinet_icmp_reply(n, m);
230 #endif
231 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
232 m_align(m, ICMP_MINLEN + icmplen);
233 m->m_len = ICMP_MINLEN + icmplen;
234
235 /* XXX MRT make the outgoing packet use the same FIB
236 * that was associated with the incoming packet
237 */
238 M_SETFIB(m, M_GETFIB(n));
239 icp = mtod(m, struct icmp *);
240 V_icmpstat.icps_outhist[type]++;
241 icp->icmp_type = type;
242 if (type == ICMP_REDIRECT)
243 icp->icmp_gwaddr.s_addr = dest;
244 else {
245 icp->icmp_void = 0;
246 /*
247 * The following assignments assume an overlay with the
248 * just zeroed icmp_void field.
249 */
250 if (type == ICMP_PARAMPROB) {
251 icp->icmp_pptr = code;
252 code = 0;
253 } else if (type == ICMP_UNREACH &&
254 code == ICMP_UNREACH_NEEDFRAG && mtu) {
255 icp->icmp_nextmtu = htons(mtu);
256 }
257 }
258 icp->icmp_code = code;
259
260 /*
261 * Copy the quotation into ICMP message and
262 * convert quoted IP header back to network representation.
263 */
264 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
265 nip = &icp->icmp_ip;
266 nip->ip_len = htons(nip->ip_len);
267 nip->ip_off = htons(nip->ip_off);
268
269 /*
270 * Set up ICMP message mbuf and copy old IP header (without options
271 * in front of ICMP message.
272 * If the original mbuf was meant to bypass the firewall, the error
273 * reply should bypass as well.
274 */
275 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
276 m->m_data -= sizeof(struct ip);
277 m->m_len += sizeof(struct ip);
278 m->m_pkthdr.len = m->m_len;
279 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
280 nip = mtod(m, struct ip *);
281 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
282 nip->ip_len = m->m_len;
283 nip->ip_v = IPVERSION;
284 nip->ip_hl = 5;
285 nip->ip_p = IPPROTO_ICMP;
286 nip->ip_tos = 0;
287 icmp_reflect(m);
288
289 freeit:
290 m_freem(n);
291 }
292
293 /*
294 * Process a received ICMP message.
295 */
296 void
297 icmp_input(struct mbuf *m, int off)
298 {
299 INIT_VNET_INET(curvnet);
300 struct icmp *icp;
301 struct in_ifaddr *ia;
302 struct ip *ip = mtod(m, struct ip *);
303 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
304 int hlen = off;
305 int icmplen = ip->ip_len;
306 int i, code;
307 void (*ctlfunc)(int, struct sockaddr *, void *);
308 int fibnum;
309
310 /*
311 * Locate icmp structure in mbuf, and check
312 * that not corrupted and of at least minimum length.
313 */
314 #ifdef ICMPPRINTFS
315 if (icmpprintfs) {
316 char buf[4 * sizeof "123"];
317 strcpy(buf, inet_ntoa(ip->ip_src));
318 printf("icmp_input from %s to %s, len %d\n",
319 buf, inet_ntoa(ip->ip_dst), icmplen);
320 }
321 #endif
322 if (icmplen < ICMP_MINLEN) {
323 V_icmpstat.icps_tooshort++;
324 goto freeit;
325 }
326 i = hlen + min(icmplen, ICMP_ADVLENMIN);
327 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
328 V_icmpstat.icps_tooshort++;
329 return;
330 }
331 ip = mtod(m, struct ip *);
332 m->m_len -= hlen;
333 m->m_data += hlen;
334 icp = mtod(m, struct icmp *);
335 if (in_cksum(m, icmplen)) {
336 V_icmpstat.icps_checksum++;
337 goto freeit;
338 }
339 m->m_len += hlen;
340 m->m_data -= hlen;
341
342 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
343 /*
344 * Deliver very specific ICMP type only.
345 */
346 switch (icp->icmp_type) {
347 case ICMP_UNREACH:
348 case ICMP_TIMXCEED:
349 break;
350 default:
351 goto freeit;
352 }
353 }
354
355 #ifdef ICMPPRINTFS
356 if (icmpprintfs)
357 printf("icmp_input, type %d code %d\n", icp->icmp_type,
358 icp->icmp_code);
359 #endif
360
361 /*
362 * Message type specific processing.
363 */
364 if (icp->icmp_type > ICMP_MAXTYPE)
365 goto raw;
366
367 /* Initialize */
368 bzero(&icmpsrc, sizeof(icmpsrc));
369 icmpsrc.sin_len = sizeof(struct sockaddr_in);
370 icmpsrc.sin_family = AF_INET;
371 bzero(&icmpdst, sizeof(icmpdst));
372 icmpdst.sin_len = sizeof(struct sockaddr_in);
373 icmpdst.sin_family = AF_INET;
374 bzero(&icmpgw, sizeof(icmpgw));
375 icmpgw.sin_len = sizeof(struct sockaddr_in);
376 icmpgw.sin_family = AF_INET;
377
378 V_icmpstat.icps_inhist[icp->icmp_type]++;
379 code = icp->icmp_code;
380 switch (icp->icmp_type) {
381
382 case ICMP_UNREACH:
383 switch (code) {
384 case ICMP_UNREACH_NET:
385 case ICMP_UNREACH_HOST:
386 case ICMP_UNREACH_SRCFAIL:
387 case ICMP_UNREACH_NET_UNKNOWN:
388 case ICMP_UNREACH_HOST_UNKNOWN:
389 case ICMP_UNREACH_ISOLATED:
390 case ICMP_UNREACH_TOSNET:
391 case ICMP_UNREACH_TOSHOST:
392 case ICMP_UNREACH_HOST_PRECEDENCE:
393 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
394 code = PRC_UNREACH_NET;
395 break;
396
397 case ICMP_UNREACH_NEEDFRAG:
398 code = PRC_MSGSIZE;
399 break;
400
401 /*
402 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
403 * Treat subcodes 2,3 as immediate RST
404 */
405 case ICMP_UNREACH_PROTOCOL:
406 case ICMP_UNREACH_PORT:
407 code = PRC_UNREACH_PORT;
408 break;
409
410 case ICMP_UNREACH_NET_PROHIB:
411 case ICMP_UNREACH_HOST_PROHIB:
412 case ICMP_UNREACH_FILTER_PROHIB:
413 code = PRC_UNREACH_ADMIN_PROHIB;
414 break;
415
416 default:
417 goto badcode;
418 }
419 goto deliver;
420
421 case ICMP_TIMXCEED:
422 if (code > 1)
423 goto badcode;
424 code += PRC_TIMXCEED_INTRANS;
425 goto deliver;
426
427 case ICMP_PARAMPROB:
428 if (code > 1)
429 goto badcode;
430 code = PRC_PARAMPROB;
431 goto deliver;
432
433 case ICMP_SOURCEQUENCH:
434 if (code)
435 goto badcode;
436 code = PRC_QUENCH;
437 deliver:
438 /*
439 * Problem with datagram; advise higher level routines.
440 */
441 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
442 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
443 V_icmpstat.icps_badlen++;
444 goto freeit;
445 }
446 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
447 /* Discard ICMP's in response to multicast packets */
448 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
449 goto badcode;
450 #ifdef ICMPPRINTFS
451 if (icmpprintfs)
452 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
453 #endif
454 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
455 /*
456 * XXX if the packet contains [IPv4 AH TCP], we can't make a
457 * notification to TCP layer.
458 */
459 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
460 if (ctlfunc)
461 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
462 (void *)&icp->icmp_ip);
463 break;
464
465 badcode:
466 V_icmpstat.icps_badcode++;
467 break;
468
469 case ICMP_ECHO:
470 if (!V_icmpbmcastecho
471 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
472 V_icmpstat.icps_bmcastecho++;
473 break;
474 }
475 icp->icmp_type = ICMP_ECHOREPLY;
476 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
477 goto freeit;
478 else
479 goto reflect;
480
481 case ICMP_TSTAMP:
482 if (!V_icmpbmcastecho
483 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
484 V_icmpstat.icps_bmcasttstamp++;
485 break;
486 }
487 if (icmplen < ICMP_TSLEN) {
488 V_icmpstat.icps_badlen++;
489 break;
490 }
491 icp->icmp_type = ICMP_TSTAMPREPLY;
492 icp->icmp_rtime = iptime();
493 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
494 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
495 goto freeit;
496 else
497 goto reflect;
498
499 case ICMP_MASKREQ:
500 if (V_icmpmaskrepl == 0)
501 break;
502 /*
503 * We are not able to respond with all ones broadcast
504 * unless we receive it over a point-to-point interface.
505 */
506 if (icmplen < ICMP_MASKLEN)
507 break;
508 switch (ip->ip_dst.s_addr) {
509
510 case INADDR_BROADCAST:
511 case INADDR_ANY:
512 icmpdst.sin_addr = ip->ip_src;
513 break;
514
515 default:
516 icmpdst.sin_addr = ip->ip_dst;
517 }
518 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
519 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
520 if (ia == 0)
521 break;
522 if (ia->ia_ifp == 0)
523 break;
524 icp->icmp_type = ICMP_MASKREPLY;
525 if (V_icmpmaskfake == 0)
526 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
527 else
528 icp->icmp_mask = V_icmpmaskfake;
529 if (ip->ip_src.s_addr == 0) {
530 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
531 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
532 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
533 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
534 }
535 reflect:
536 ip->ip_len += hlen; /* since ip_input deducts this */
537 V_icmpstat.icps_reflect++;
538 V_icmpstat.icps_outhist[icp->icmp_type]++;
539 icmp_reflect(m);
540 return;
541
542 case ICMP_REDIRECT:
543 if (V_log_redirect) {
544 u_long src, dst, gw;
545
546 src = ntohl(ip->ip_src.s_addr);
547 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
548 gw = ntohl(icp->icmp_gwaddr.s_addr);
549 printf("icmp redirect from %d.%d.%d.%d: "
550 "%d.%d.%d.%d => %d.%d.%d.%d\n",
551 (int)(src >> 24), (int)((src >> 16) & 0xff),
552 (int)((src >> 8) & 0xff), (int)(src & 0xff),
553 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
554 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
555 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
556 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
557 }
558 /*
559 * RFC1812 says we must ignore ICMP redirects if we
560 * are acting as router.
561 */
562 if (V_drop_redirect || V_ipforwarding)
563 break;
564 if (code > 3)
565 goto badcode;
566 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
567 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
568 V_icmpstat.icps_badlen++;
569 break;
570 }
571 /*
572 * Short circuit routing redirects to force
573 * immediate change in the kernel's routing
574 * tables. The message is also handed to anyone
575 * listening on a raw socket (e.g. the routing
576 * daemon for use in updating its tables).
577 */
578 icmpgw.sin_addr = ip->ip_src;
579 icmpdst.sin_addr = icp->icmp_gwaddr;
580 #ifdef ICMPPRINTFS
581 if (icmpprintfs) {
582 char buf[4 * sizeof "123"];
583 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
584
585 printf("redirect dst %s to %s\n",
586 buf, inet_ntoa(icp->icmp_gwaddr));
587 }
588 #endif
589 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
590 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
591 in_rtredirect((struct sockaddr *)&icmpsrc,
592 (struct sockaddr *)&icmpdst,
593 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
594 (struct sockaddr *)&icmpgw, fibnum);
595 }
596 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
597 #ifdef IPSEC
598 key_sa_routechange((struct sockaddr *)&icmpsrc);
599 #endif
600 break;
601
602 /*
603 * No kernel processing for the following;
604 * just fall through to send to raw listener.
605 */
606 case ICMP_ECHOREPLY:
607 case ICMP_ROUTERADVERT:
608 case ICMP_ROUTERSOLICIT:
609 case ICMP_TSTAMPREPLY:
610 case ICMP_IREQREPLY:
611 case ICMP_MASKREPLY:
612 default:
613 break;
614 }
615
616 raw:
617 rip_input(m, off);
618 return;
619
620 freeit:
621 m_freem(m);
622 }
623
624 /*
625 * Reflect the ip packet back to the source
626 */
627 static void
628 icmp_reflect(struct mbuf *m)
629 {
630 INIT_VNET_INET(curvnet);
631 struct ip *ip = mtod(m, struct ip *);
632 struct ifaddr *ifa;
633 struct ifnet *ifn;
634 struct in_ifaddr *ia;
635 struct in_addr t;
636 struct mbuf *opts = 0;
637 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
638
639 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
640 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
641 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
642 m_freem(m); /* Bad return address */
643 V_icmpstat.icps_badaddr++;
644 goto done; /* Ip_output() will check for broadcast */
645 }
646
647 t = ip->ip_dst;
648 ip->ip_dst = ip->ip_src;
649
650 /*
651 * Source selection for ICMP replies:
652 *
653 * If the incoming packet was addressed directly to one of our
654 * own addresses, use dst as the src for the reply.
655 */
656 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
657 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
658 goto match;
659 /*
660 * If the incoming packet was addressed to one of our broadcast
661 * addresses, use the first non-broadcast address which corresponds
662 * to the incoming interface.
663 */
664 if (m->m_pkthdr.rcvif != NULL &&
665 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
666 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
667 if (ifa->ifa_addr->sa_family != AF_INET)
668 continue;
669 ia = ifatoia(ifa);
670 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
671 t.s_addr)
672 goto match;
673 }
674 }
675 /*
676 * If the packet was transiting through us, use the address of
677 * the interface the packet came through in. If that interface
678 * doesn't have a suitable IP address, the normal selection
679 * criteria apply.
680 */
681 if (V_icmp_rfi && m->m_pkthdr.rcvif != NULL) {
682 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
683 if (ifa->ifa_addr->sa_family != AF_INET)
684 continue;
685 ia = ifatoia(ifa);
686 goto match;
687 }
688 }
689 /*
690 * If the incoming packet was not addressed directly to us, use
691 * designated interface for icmp replies specified by sysctl
692 * net.inet.icmp.reply_src (default not set). Otherwise continue
693 * with normal source selection.
694 */
695 if (V_reply_src[0] != '\0' && (ifn = ifunit(V_reply_src))) {
696 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) {
697 if (ifa->ifa_addr->sa_family != AF_INET)
698 continue;
699 ia = ifatoia(ifa);
700 goto match;
701 }
702 }
703 /*
704 * If the packet was transiting through us, use the address of
705 * the interface that is the closest to the packet source.
706 * When we don't have a route back to the packet source, stop here
707 * and drop the packet.
708 */
709 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
710 if (ia == NULL) {
711 m_freem(m);
712 V_icmpstat.icps_noroute++;
713 goto done;
714 }
715 match:
716 #ifdef MAC
717 mac_netinet_icmp_replyinplace(m);
718 #endif
719 t = IA_SIN(ia)->sin_addr;
720 ip->ip_src = t;
721 ip->ip_ttl = V_ip_defttl;
722
723 if (optlen > 0) {
724 register u_char *cp;
725 int opt, cnt;
726 u_int len;
727
728 /*
729 * Retrieve any source routing from the incoming packet;
730 * add on any record-route or timestamp options.
731 */
732 cp = (u_char *) (ip + 1);
733 if ((opts = ip_srcroute(m)) == 0 &&
734 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
735 opts->m_len = sizeof(struct in_addr);
736 mtod(opts, struct in_addr *)->s_addr = 0;
737 }
738 if (opts) {
739 #ifdef ICMPPRINTFS
740 if (icmpprintfs)
741 printf("icmp_reflect optlen %d rt %d => ",
742 optlen, opts->m_len);
743 #endif
744 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
745 opt = cp[IPOPT_OPTVAL];
746 if (opt == IPOPT_EOL)
747 break;
748 if (opt == IPOPT_NOP)
749 len = 1;
750 else {
751 if (cnt < IPOPT_OLEN + sizeof(*cp))
752 break;
753 len = cp[IPOPT_OLEN];
754 if (len < IPOPT_OLEN + sizeof(*cp) ||
755 len > cnt)
756 break;
757 }
758 /*
759 * Should check for overflow, but it "can't happen"
760 */
761 if (opt == IPOPT_RR || opt == IPOPT_TS ||
762 opt == IPOPT_SECURITY) {
763 bcopy((caddr_t)cp,
764 mtod(opts, caddr_t) + opts->m_len, len);
765 opts->m_len += len;
766 }
767 }
768 /* Terminate & pad, if necessary */
769 cnt = opts->m_len % 4;
770 if (cnt) {
771 for (; cnt < 4; cnt++) {
772 *(mtod(opts, caddr_t) + opts->m_len) =
773 IPOPT_EOL;
774 opts->m_len++;
775 }
776 }
777 #ifdef ICMPPRINTFS
778 if (icmpprintfs)
779 printf("%d\n", opts->m_len);
780 #endif
781 }
782 /*
783 * Now strip out original options by copying rest of first
784 * mbuf's data back, and adjust the IP length.
785 */
786 ip->ip_len -= optlen;
787 ip->ip_v = IPVERSION;
788 ip->ip_hl = 5;
789 m->m_len -= optlen;
790 if (m->m_flags & M_PKTHDR)
791 m->m_pkthdr.len -= optlen;
792 optlen += sizeof(struct ip);
793 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
794 (unsigned)(m->m_len - sizeof(struct ip)));
795 }
796 m_tag_delete_nonpersistent(m);
797 m->m_flags &= ~(M_BCAST|M_MCAST);
798 icmp_send(m, opts);
799 done:
800 if (opts)
801 (void)m_free(opts);
802 }
803
804 /*
805 * Send an icmp packet back to the ip level,
806 * after supplying a checksum.
807 */
808 static void
809 icmp_send(struct mbuf *m, struct mbuf *opts)
810 {
811 register struct ip *ip = mtod(m, struct ip *);
812 register int hlen;
813 register struct icmp *icp;
814
815 hlen = ip->ip_hl << 2;
816 m->m_data += hlen;
817 m->m_len -= hlen;
818 icp = mtod(m, struct icmp *);
819 icp->icmp_cksum = 0;
820 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
821 m->m_data -= hlen;
822 m->m_len += hlen;
823 m->m_pkthdr.rcvif = (struct ifnet *)0;
824 #ifdef ICMPPRINTFS
825 if (icmpprintfs) {
826 char buf[4 * sizeof "123"];
827 strcpy(buf, inet_ntoa(ip->ip_dst));
828 printf("icmp_send dst %s src %s\n",
829 buf, inet_ntoa(ip->ip_src));
830 }
831 #endif
832 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
833 }
834
835 n_time
836 iptime(void)
837 {
838 struct timeval atv;
839 u_long t;
840
841 getmicrotime(&atv);
842 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
843 return (htonl(t));
844 }
845
846 /*
847 * Return the next larger or smaller MTU plateau (table from RFC 1191)
848 * given current value MTU. If DIR is less than zero, a larger plateau
849 * is returned; otherwise, a smaller value is returned.
850 */
851 int
852 ip_next_mtu(int mtu, int dir)
853 {
854 static int mtutab[] = {
855 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
856 296, 68, 0
857 };
858 int i, size;
859
860 size = (sizeof mtutab) / (sizeof mtutab[0]);
861 if (dir >= 0) {
862 for (i = 0; i < size; i++)
863 if (mtu > mtutab[i])
864 return mtutab[i];
865 } else {
866 for (i = size - 1; i >= 0; i--)
867 if (mtu < mtutab[i])
868 return mtutab[i];
869 if (mtu == mtutab[0])
870 return mtutab[0];
871 }
872 return 0;
873 }
874
875
876 /*
877 * badport_bandlim() - check for ICMP bandwidth limit
878 *
879 * Return 0 if it is ok to send an ICMP error response, -1 if we have
880 * hit our bandwidth limit and it is not ok.
881 *
882 * If icmplim is <= 0, the feature is disabled and 0 is returned.
883 *
884 * For now we separate the TCP and UDP subsystems w/ different 'which'
885 * values. We may eventually remove this separation (and simplify the
886 * code further).
887 *
888 * Note that the printing of the error message is delayed so we can
889 * properly print the icmp error rate that the system was trying to do
890 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
891 * the 'final' error, but it doesn't make sense to solve the printing
892 * delay with more complex code.
893 */
894
895 int
896 badport_bandlim(int which)
897 {
898 INIT_VNET_INET(curvnet);
899
900 #define N(a) (sizeof (a) / sizeof (a[0]))
901 static struct rate {
902 const char *type;
903 struct timeval lasttime;
904 int curpps;
905 } rates[BANDLIM_MAX+1] = {
906 { "icmp unreach response" },
907 { "icmp ping response" },
908 { "icmp tstamp response" },
909 { "closed port RST response" },
910 { "open port RST response" },
911 { "icmp6 unreach response" }
912 };
913
914 /*
915 * Return ok status if feature disabled or argument out of range.
916 */
917 if (V_icmplim > 0 && (u_int) which < N(rates)) {
918 struct rate *r = &rates[which];
919 int opps = r->curpps;
920
921 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
922 return -1; /* discard packet */
923 /*
924 * If we've dropped below the threshold after having
925 * rate-limited traffic print the message. This preserves
926 * the previous behaviour at the expense of added complexity.
927 */
928 if (V_icmplim_output && opps > V_icmplim)
929 printf("Limiting %s from %d to %d packets/sec\n",
930 r->type, opps, V_icmplim);
931 }
932 return 0; /* okay to send packet */
933 #undef N
934 }
935
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