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/8.1/sys/netinet/ip_icmp.c 207695 2010-05-06 06:44:19Z bz $");
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 VNET_DEFINE(struct icmpstat, icmpstat);
79 SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
80 &VNET_NAME(icmpstat), icmpstat, "");
81
82 static VNET_DEFINE(int, icmpmaskrepl) = 0;
83 #define V_icmpmaskrepl VNET(icmpmaskrepl)
84 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
85 &VNET_NAME(icmpmaskrepl), 0,
86 "Reply to ICMP Address Mask Request packets.");
87
88 static VNET_DEFINE(u_int, icmpmaskfake) = 0;
89 #define V_icmpmaskfake VNET(icmpmaskfake)
90 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
91 &VNET_NAME(icmpmaskfake), 0,
92 "Fake reply to ICMP Address Mask Request packets.");
93
94 static VNET_DEFINE(int, drop_redirect) = 0;
95 #define V_drop_redirect VNET(drop_redirect)
96 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
97 &VNET_NAME(drop_redirect), 0,
98 "Ignore ICMP redirects");
99
100 static VNET_DEFINE(int, log_redirect) = 0;
101 #define V_log_redirect VNET(log_redirect)
102 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
103 &VNET_NAME(log_redirect), 0,
104 "Log ICMP redirects to the console");
105
106 static VNET_DEFINE(int, icmplim) = 200;
107 #define V_icmplim VNET(icmplim)
108 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
109 &VNET_NAME(icmplim), 0,
110 "Maximum number of ICMP responses per second");
111
112 static VNET_DEFINE(int, icmplim_output) = 1;
113 #define V_icmplim_output VNET(icmplim_output)
114 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
115 &VNET_NAME(icmplim_output), 0,
116 "Enable rate limiting of ICMP responses");
117
118 static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
119 #define V_reply_src VNET(reply_src)
120 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
121 &VNET_NAME(reply_src), IFNAMSIZ,
122 "icmp reply source for non-local packets.");
123
124 static VNET_DEFINE(int, icmp_rfi) = 0;
125 #define V_icmp_rfi VNET(icmp_rfi)
126 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
127 &VNET_NAME(icmp_rfi), 0,
128 "ICMP reply from incoming interface for non-local packets");
129
130 static VNET_DEFINE(int, icmp_quotelen) = 8;
131 #define V_icmp_quotelen VNET(icmp_quotelen)
132 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
133 &VNET_NAME(icmp_quotelen), 0,
134 "Number of bytes from original packet to quote in ICMP reply");
135
136 /*
137 * ICMP broadcast echo sysctl
138 */
139 static VNET_DEFINE(int, icmpbmcastecho) = 0;
140 #define V_icmpbmcastecho VNET(icmpbmcastecho)
141 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
142 &VNET_NAME(icmpbmcastecho), 0,
143 "");
144
145
146 #ifdef ICMPPRINTFS
147 int icmpprintfs = 0;
148 #endif
149
150 static void icmp_reflect(struct mbuf *);
151 static void icmp_send(struct mbuf *, struct mbuf *);
152
153 extern struct protosw inetsw[];
154
155 /*
156 * Kernel module interface for updating icmpstat. The argument is an index
157 * into icmpstat treated as an array of u_long. While this encodes the
158 * general layout of icmpstat into the caller, it doesn't encode its
159 * location, so that future changes to add, for example, per-CPU stats
160 * support won't cause binary compatibility problems for kernel modules.
161 */
162 void
163 kmod_icmpstat_inc(int statnum)
164 {
165
166 (*((u_long *)&V_icmpstat + statnum))++;
167 }
168
169 /*
170 * Generate an error packet of type error
171 * in response to bad packet ip.
172 */
173 void
174 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
175 {
176 register struct ip *oip = mtod(n, struct ip *), *nip;
177 register unsigned oiphlen = oip->ip_hl << 2;
178 register struct icmp *icp;
179 register struct mbuf *m;
180 unsigned icmplen, icmpelen, nlen;
181
182 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
183 #ifdef ICMPPRINTFS
184 if (icmpprintfs)
185 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
186 #endif
187 if (type != ICMP_REDIRECT)
188 ICMPSTAT_INC(icps_error);
189 /*
190 * Don't send error:
191 * if the original packet was encrypted.
192 * if not the first fragment of message.
193 * in response to a multicast or broadcast packet.
194 * if the old packet protocol was an ICMP error message.
195 */
196 if (n->m_flags & M_DECRYPTED)
197 goto freeit;
198 if (oip->ip_off & ~(IP_MF|IP_DF))
199 goto freeit;
200 if (n->m_flags & (M_BCAST|M_MCAST))
201 goto freeit;
202 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
203 n->m_len >= oiphlen + ICMP_MINLEN &&
204 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
205 ICMPSTAT_INC(icps_oldicmp);
206 goto freeit;
207 }
208 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
209 if (oiphlen + 8 > n->m_len)
210 goto freeit;
211 /*
212 * Calculate length to quote from original packet and
213 * prevent the ICMP mbuf from overflowing.
214 * Unfortunatly this is non-trivial since ip_forward()
215 * sends us truncated packets.
216 */
217 nlen = m_length(n, NULL);
218 if (oip->ip_p == IPPROTO_TCP) {
219 struct tcphdr *th;
220 int tcphlen;
221
222 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
223 n->m_next == NULL)
224 goto stdreply;
225 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
226 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
227 goto freeit;
228 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
229 tcphlen = th->th_off << 2;
230 if (tcphlen < sizeof(struct tcphdr))
231 goto freeit;
232 if (oip->ip_len < oiphlen + tcphlen)
233 goto freeit;
234 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
235 goto stdreply;
236 if (n->m_len < oiphlen + tcphlen &&
237 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
238 goto freeit;
239 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen));
240 } else
241 stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen));
242
243 icmplen = min(oiphlen + icmpelen, nlen);
244 if (icmplen < sizeof(struct ip))
245 goto freeit;
246
247 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
248 m = m_gethdr(M_DONTWAIT, MT_DATA);
249 else
250 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
251 if (m == NULL)
252 goto freeit;
253 #ifdef MAC
254 mac_netinet_icmp_reply(n, m);
255 #endif
256 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
257 m_align(m, ICMP_MINLEN + icmplen);
258 m->m_len = ICMP_MINLEN + icmplen;
259
260 /* XXX MRT make the outgoing packet use the same FIB
261 * that was associated with the incoming packet
262 */
263 M_SETFIB(m, M_GETFIB(n));
264 icp = mtod(m, struct icmp *);
265 ICMPSTAT_INC(icps_outhist[type]);
266 icp->icmp_type = type;
267 if (type == ICMP_REDIRECT)
268 icp->icmp_gwaddr.s_addr = dest;
269 else {
270 icp->icmp_void = 0;
271 /*
272 * The following assignments assume an overlay with the
273 * just zeroed icmp_void field.
274 */
275 if (type == ICMP_PARAMPROB) {
276 icp->icmp_pptr = code;
277 code = 0;
278 } else if (type == ICMP_UNREACH &&
279 code == ICMP_UNREACH_NEEDFRAG && mtu) {
280 icp->icmp_nextmtu = htons(mtu);
281 }
282 }
283 icp->icmp_code = code;
284
285 /*
286 * Copy the quotation into ICMP message and
287 * convert quoted IP header back to network representation.
288 */
289 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
290 nip = &icp->icmp_ip;
291 nip->ip_len = htons(nip->ip_len);
292 nip->ip_off = htons(nip->ip_off);
293
294 /*
295 * Set up ICMP message mbuf and copy old IP header (without options
296 * in front of ICMP message.
297 * If the original mbuf was meant to bypass the firewall, the error
298 * reply should bypass as well.
299 */
300 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
301 m->m_data -= sizeof(struct ip);
302 m->m_len += sizeof(struct ip);
303 m->m_pkthdr.len = m->m_len;
304 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
305 nip = mtod(m, struct ip *);
306 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
307 nip->ip_len = m->m_len;
308 nip->ip_v = IPVERSION;
309 nip->ip_hl = 5;
310 nip->ip_p = IPPROTO_ICMP;
311 nip->ip_tos = 0;
312 icmp_reflect(m);
313
314 freeit:
315 m_freem(n);
316 }
317
318 /*
319 * Process a received ICMP message.
320 */
321 void
322 icmp_input(struct mbuf *m, int off)
323 {
324 struct icmp *icp;
325 struct in_ifaddr *ia;
326 struct ip *ip = mtod(m, struct ip *);
327 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
328 int hlen = off;
329 int icmplen = ip->ip_len;
330 int i, code;
331 void (*ctlfunc)(int, struct sockaddr *, void *);
332 int fibnum;
333
334 /*
335 * Locate icmp structure in mbuf, and check
336 * that not corrupted and of at least minimum length.
337 */
338 #ifdef ICMPPRINTFS
339 if (icmpprintfs) {
340 char buf[4 * sizeof "123"];
341 strcpy(buf, inet_ntoa(ip->ip_src));
342 printf("icmp_input from %s to %s, len %d\n",
343 buf, inet_ntoa(ip->ip_dst), icmplen);
344 }
345 #endif
346 if (icmplen < ICMP_MINLEN) {
347 ICMPSTAT_INC(icps_tooshort);
348 goto freeit;
349 }
350 i = hlen + min(icmplen, ICMP_ADVLENMIN);
351 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
352 ICMPSTAT_INC(icps_tooshort);
353 return;
354 }
355 ip = mtod(m, struct ip *);
356 m->m_len -= hlen;
357 m->m_data += hlen;
358 icp = mtod(m, struct icmp *);
359 if (in_cksum(m, icmplen)) {
360 ICMPSTAT_INC(icps_checksum);
361 goto freeit;
362 }
363 m->m_len += hlen;
364 m->m_data -= hlen;
365
366 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
367 /*
368 * Deliver very specific ICMP type only.
369 */
370 switch (icp->icmp_type) {
371 case ICMP_UNREACH:
372 case ICMP_TIMXCEED:
373 break;
374 default:
375 goto freeit;
376 }
377 }
378
379 #ifdef ICMPPRINTFS
380 if (icmpprintfs)
381 printf("icmp_input, type %d code %d\n", icp->icmp_type,
382 icp->icmp_code);
383 #endif
384
385 /*
386 * Message type specific processing.
387 */
388 if (icp->icmp_type > ICMP_MAXTYPE)
389 goto raw;
390
391 /* Initialize */
392 bzero(&icmpsrc, sizeof(icmpsrc));
393 icmpsrc.sin_len = sizeof(struct sockaddr_in);
394 icmpsrc.sin_family = AF_INET;
395 bzero(&icmpdst, sizeof(icmpdst));
396 icmpdst.sin_len = sizeof(struct sockaddr_in);
397 icmpdst.sin_family = AF_INET;
398 bzero(&icmpgw, sizeof(icmpgw));
399 icmpgw.sin_len = sizeof(struct sockaddr_in);
400 icmpgw.sin_family = AF_INET;
401
402 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
403 code = icp->icmp_code;
404 switch (icp->icmp_type) {
405
406 case ICMP_UNREACH:
407 switch (code) {
408 case ICMP_UNREACH_NET:
409 case ICMP_UNREACH_HOST:
410 case ICMP_UNREACH_SRCFAIL:
411 case ICMP_UNREACH_NET_UNKNOWN:
412 case ICMP_UNREACH_HOST_UNKNOWN:
413 case ICMP_UNREACH_ISOLATED:
414 case ICMP_UNREACH_TOSNET:
415 case ICMP_UNREACH_TOSHOST:
416 case ICMP_UNREACH_HOST_PRECEDENCE:
417 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
418 code = PRC_UNREACH_NET;
419 break;
420
421 case ICMP_UNREACH_NEEDFRAG:
422 code = PRC_MSGSIZE;
423 break;
424
425 /*
426 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
427 * Treat subcodes 2,3 as immediate RST
428 */
429 case ICMP_UNREACH_PROTOCOL:
430 case ICMP_UNREACH_PORT:
431 code = PRC_UNREACH_PORT;
432 break;
433
434 case ICMP_UNREACH_NET_PROHIB:
435 case ICMP_UNREACH_HOST_PROHIB:
436 case ICMP_UNREACH_FILTER_PROHIB:
437 code = PRC_UNREACH_ADMIN_PROHIB;
438 break;
439
440 default:
441 goto badcode;
442 }
443 goto deliver;
444
445 case ICMP_TIMXCEED:
446 if (code > 1)
447 goto badcode;
448 code += PRC_TIMXCEED_INTRANS;
449 goto deliver;
450
451 case ICMP_PARAMPROB:
452 if (code > 1)
453 goto badcode;
454 code = PRC_PARAMPROB;
455 goto deliver;
456
457 case ICMP_SOURCEQUENCH:
458 if (code)
459 goto badcode;
460 code = PRC_QUENCH;
461 deliver:
462 /*
463 * Problem with datagram; advise higher level routines.
464 */
465 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
466 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
467 ICMPSTAT_INC(icps_badlen);
468 goto freeit;
469 }
470 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
471 /* Discard ICMP's in response to multicast packets */
472 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
473 goto badcode;
474 #ifdef ICMPPRINTFS
475 if (icmpprintfs)
476 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
477 #endif
478 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
479 /*
480 * XXX if the packet contains [IPv4 AH TCP], we can't make a
481 * notification to TCP layer.
482 */
483 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
484 if (ctlfunc)
485 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
486 (void *)&icp->icmp_ip);
487 break;
488
489 badcode:
490 ICMPSTAT_INC(icps_badcode);
491 break;
492
493 case ICMP_ECHO:
494 if (!V_icmpbmcastecho
495 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
496 ICMPSTAT_INC(icps_bmcastecho);
497 break;
498 }
499 icp->icmp_type = ICMP_ECHOREPLY;
500 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
501 goto freeit;
502 else
503 goto reflect;
504
505 case ICMP_TSTAMP:
506 if (!V_icmpbmcastecho
507 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
508 ICMPSTAT_INC(icps_bmcasttstamp);
509 break;
510 }
511 if (icmplen < ICMP_TSLEN) {
512 ICMPSTAT_INC(icps_badlen);
513 break;
514 }
515 icp->icmp_type = ICMP_TSTAMPREPLY;
516 icp->icmp_rtime = iptime();
517 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
518 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
519 goto freeit;
520 else
521 goto reflect;
522
523 case ICMP_MASKREQ:
524 if (V_icmpmaskrepl == 0)
525 break;
526 /*
527 * We are not able to respond with all ones broadcast
528 * unless we receive it over a point-to-point interface.
529 */
530 if (icmplen < ICMP_MASKLEN)
531 break;
532 switch (ip->ip_dst.s_addr) {
533
534 case INADDR_BROADCAST:
535 case INADDR_ANY:
536 icmpdst.sin_addr = ip->ip_src;
537 break;
538
539 default:
540 icmpdst.sin_addr = ip->ip_dst;
541 }
542 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
543 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
544 if (ia == NULL)
545 break;
546 if (ia->ia_ifp == NULL) {
547 ifa_free(&ia->ia_ifa);
548 break;
549 }
550 icp->icmp_type = ICMP_MASKREPLY;
551 if (V_icmpmaskfake == 0)
552 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
553 else
554 icp->icmp_mask = V_icmpmaskfake;
555 if (ip->ip_src.s_addr == 0) {
556 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
557 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
558 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
559 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
560 }
561 ifa_free(&ia->ia_ifa);
562 reflect:
563 ip->ip_len += hlen; /* since ip_input deducts this */
564 ICMPSTAT_INC(icps_reflect);
565 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
566 icmp_reflect(m);
567 return;
568
569 case ICMP_REDIRECT:
570 if (V_log_redirect) {
571 u_long src, dst, gw;
572
573 src = ntohl(ip->ip_src.s_addr);
574 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
575 gw = ntohl(icp->icmp_gwaddr.s_addr);
576 printf("icmp redirect from %d.%d.%d.%d: "
577 "%d.%d.%d.%d => %d.%d.%d.%d\n",
578 (int)(src >> 24), (int)((src >> 16) & 0xff),
579 (int)((src >> 8) & 0xff), (int)(src & 0xff),
580 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
581 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
582 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
583 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
584 }
585 /*
586 * RFC1812 says we must ignore ICMP redirects if we
587 * are acting as router.
588 */
589 if (V_drop_redirect || V_ipforwarding)
590 break;
591 if (code > 3)
592 goto badcode;
593 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
594 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
595 ICMPSTAT_INC(icps_badlen);
596 break;
597 }
598 /*
599 * Short circuit routing redirects to force
600 * immediate change in the kernel's routing
601 * tables. The message is also handed to anyone
602 * listening on a raw socket (e.g. the routing
603 * daemon for use in updating its tables).
604 */
605 icmpgw.sin_addr = ip->ip_src;
606 icmpdst.sin_addr = icp->icmp_gwaddr;
607 #ifdef ICMPPRINTFS
608 if (icmpprintfs) {
609 char buf[4 * sizeof "123"];
610 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
611
612 printf("redirect dst %s to %s\n",
613 buf, inet_ntoa(icp->icmp_gwaddr));
614 }
615 #endif
616 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
617 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
618 in_rtredirect((struct sockaddr *)&icmpsrc,
619 (struct sockaddr *)&icmpdst,
620 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
621 (struct sockaddr *)&icmpgw, fibnum);
622 }
623 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
624 #ifdef IPSEC
625 key_sa_routechange((struct sockaddr *)&icmpsrc);
626 #endif
627 break;
628
629 /*
630 * No kernel processing for the following;
631 * just fall through to send to raw listener.
632 */
633 case ICMP_ECHOREPLY:
634 case ICMP_ROUTERADVERT:
635 case ICMP_ROUTERSOLICIT:
636 case ICMP_TSTAMPREPLY:
637 case ICMP_IREQREPLY:
638 case ICMP_MASKREPLY:
639 default:
640 break;
641 }
642
643 raw:
644 rip_input(m, off);
645 return;
646
647 freeit:
648 m_freem(m);
649 }
650
651 /*
652 * Reflect the ip packet back to the source
653 */
654 static void
655 icmp_reflect(struct mbuf *m)
656 {
657 struct ip *ip = mtod(m, struct ip *);
658 struct ifaddr *ifa;
659 struct ifnet *ifp;
660 struct in_ifaddr *ia;
661 struct in_addr t;
662 struct mbuf *opts = 0;
663 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
664
665 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
666 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
667 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
668 m_freem(m); /* Bad return address */
669 ICMPSTAT_INC(icps_badaddr);
670 goto done; /* Ip_output() will check for broadcast */
671 }
672
673 t = ip->ip_dst;
674 ip->ip_dst = ip->ip_src;
675
676 /*
677 * Source selection for ICMP replies:
678 *
679 * If the incoming packet was addressed directly to one of our
680 * own addresses, use dst as the src for the reply.
681 */
682 IN_IFADDR_RLOCK();
683 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
684 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
685 t = IA_SIN(ia)->sin_addr;
686 IN_IFADDR_RUNLOCK();
687 goto match;
688 }
689 }
690 IN_IFADDR_RUNLOCK();
691
692 /*
693 * If the incoming packet was addressed to one of our broadcast
694 * addresses, use the first non-broadcast address which corresponds
695 * to the incoming interface.
696 */
697 ifp = m->m_pkthdr.rcvif;
698 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
699 IF_ADDR_LOCK(ifp);
700 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
701 if (ifa->ifa_addr->sa_family != AF_INET)
702 continue;
703 ia = ifatoia(ifa);
704 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
705 t.s_addr) {
706 t = IA_SIN(ia)->sin_addr;
707 IF_ADDR_UNLOCK(ifp);
708 goto match;
709 }
710 }
711 IF_ADDR_UNLOCK(ifp);
712 }
713 /*
714 * If the packet was transiting through us, use the address of
715 * the interface the packet came through in. If that interface
716 * doesn't have a suitable IP address, the normal selection
717 * criteria apply.
718 */
719 if (V_icmp_rfi && ifp != NULL) {
720 IF_ADDR_LOCK(ifp);
721 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
722 if (ifa->ifa_addr->sa_family != AF_INET)
723 continue;
724 ia = ifatoia(ifa);
725 t = IA_SIN(ia)->sin_addr;
726 IF_ADDR_UNLOCK(ifp);
727 goto match;
728 }
729 IF_ADDR_UNLOCK(ifp);
730 }
731 /*
732 * If the incoming packet was not addressed directly to us, use
733 * designated interface for icmp replies specified by sysctl
734 * net.inet.icmp.reply_src (default not set). Otherwise continue
735 * with normal source selection.
736 */
737 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
738 IF_ADDR_LOCK(ifp);
739 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
740 if (ifa->ifa_addr->sa_family != AF_INET)
741 continue;
742 ia = ifatoia(ifa);
743 t = IA_SIN(ia)->sin_addr;
744 IF_ADDR_UNLOCK(ifp);
745 goto match;
746 }
747 IF_ADDR_UNLOCK(ifp);
748 }
749 /*
750 * If the packet was transiting through us, use the address of
751 * the interface that is the closest to the packet source.
752 * When we don't have a route back to the packet source, stop here
753 * and drop the packet.
754 */
755 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
756 if (ia == NULL) {
757 m_freem(m);
758 ICMPSTAT_INC(icps_noroute);
759 goto done;
760 }
761 t = IA_SIN(ia)->sin_addr;
762 ifa_free(&ia->ia_ifa);
763 match:
764 #ifdef MAC
765 mac_netinet_icmp_replyinplace(m);
766 #endif
767 ip->ip_src = t;
768 ip->ip_ttl = V_ip_defttl;
769
770 if (optlen > 0) {
771 register u_char *cp;
772 int opt, cnt;
773 u_int len;
774
775 /*
776 * Retrieve any source routing from the incoming packet;
777 * add on any record-route or timestamp options.
778 */
779 cp = (u_char *) (ip + 1);
780 if ((opts = ip_srcroute(m)) == 0 &&
781 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
782 opts->m_len = sizeof(struct in_addr);
783 mtod(opts, struct in_addr *)->s_addr = 0;
784 }
785 if (opts) {
786 #ifdef ICMPPRINTFS
787 if (icmpprintfs)
788 printf("icmp_reflect optlen %d rt %d => ",
789 optlen, opts->m_len);
790 #endif
791 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
792 opt = cp[IPOPT_OPTVAL];
793 if (opt == IPOPT_EOL)
794 break;
795 if (opt == IPOPT_NOP)
796 len = 1;
797 else {
798 if (cnt < IPOPT_OLEN + sizeof(*cp))
799 break;
800 len = cp[IPOPT_OLEN];
801 if (len < IPOPT_OLEN + sizeof(*cp) ||
802 len > cnt)
803 break;
804 }
805 /*
806 * Should check for overflow, but it "can't happen"
807 */
808 if (opt == IPOPT_RR || opt == IPOPT_TS ||
809 opt == IPOPT_SECURITY) {
810 bcopy((caddr_t)cp,
811 mtod(opts, caddr_t) + opts->m_len, len);
812 opts->m_len += len;
813 }
814 }
815 /* Terminate & pad, if necessary */
816 cnt = opts->m_len % 4;
817 if (cnt) {
818 for (; cnt < 4; cnt++) {
819 *(mtod(opts, caddr_t) + opts->m_len) =
820 IPOPT_EOL;
821 opts->m_len++;
822 }
823 }
824 #ifdef ICMPPRINTFS
825 if (icmpprintfs)
826 printf("%d\n", opts->m_len);
827 #endif
828 }
829 /*
830 * Now strip out original options by copying rest of first
831 * mbuf's data back, and adjust the IP length.
832 */
833 ip->ip_len -= optlen;
834 ip->ip_v = IPVERSION;
835 ip->ip_hl = 5;
836 m->m_len -= optlen;
837 if (m->m_flags & M_PKTHDR)
838 m->m_pkthdr.len -= optlen;
839 optlen += sizeof(struct ip);
840 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
841 (unsigned)(m->m_len - sizeof(struct ip)));
842 }
843 m_tag_delete_nonpersistent(m);
844 m->m_flags &= ~(M_BCAST|M_MCAST);
845 icmp_send(m, opts);
846 done:
847 if (opts)
848 (void)m_free(opts);
849 }
850
851 /*
852 * Send an icmp packet back to the ip level,
853 * after supplying a checksum.
854 */
855 static void
856 icmp_send(struct mbuf *m, struct mbuf *opts)
857 {
858 register struct ip *ip = mtod(m, struct ip *);
859 register int hlen;
860 register struct icmp *icp;
861
862 hlen = ip->ip_hl << 2;
863 m->m_data += hlen;
864 m->m_len -= hlen;
865 icp = mtod(m, struct icmp *);
866 icp->icmp_cksum = 0;
867 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
868 m->m_data -= hlen;
869 m->m_len += hlen;
870 m->m_pkthdr.rcvif = (struct ifnet *)0;
871 #ifdef ICMPPRINTFS
872 if (icmpprintfs) {
873 char buf[4 * sizeof "123"];
874 strcpy(buf, inet_ntoa(ip->ip_dst));
875 printf("icmp_send dst %s src %s\n",
876 buf, inet_ntoa(ip->ip_src));
877 }
878 #endif
879 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
880 }
881
882 /*
883 * Return milliseconds since 00:00 GMT in network format.
884 */
885 uint32_t
886 iptime(void)
887 {
888 struct timeval atv;
889 u_long t;
890
891 getmicrotime(&atv);
892 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
893 return (htonl(t));
894 }
895
896 /*
897 * Return the next larger or smaller MTU plateau (table from RFC 1191)
898 * given current value MTU. If DIR is less than zero, a larger plateau
899 * is returned; otherwise, a smaller value is returned.
900 */
901 int
902 ip_next_mtu(int mtu, int dir)
903 {
904 static int mtutab[] = {
905 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
906 296, 68, 0
907 };
908 int i, size;
909
910 size = (sizeof mtutab) / (sizeof mtutab[0]);
911 if (dir >= 0) {
912 for (i = 0; i < size; i++)
913 if (mtu > mtutab[i])
914 return mtutab[i];
915 } else {
916 for (i = size - 1; i >= 0; i--)
917 if (mtu < mtutab[i])
918 return mtutab[i];
919 if (mtu == mtutab[0])
920 return mtutab[0];
921 }
922 return 0;
923 }
924
925
926 /*
927 * badport_bandlim() - check for ICMP bandwidth limit
928 *
929 * Return 0 if it is ok to send an ICMP error response, -1 if we have
930 * hit our bandwidth limit and it is not ok.
931 *
932 * If icmplim is <= 0, the feature is disabled and 0 is returned.
933 *
934 * For now we separate the TCP and UDP subsystems w/ different 'which'
935 * values. We may eventually remove this separation (and simplify the
936 * code further).
937 *
938 * Note that the printing of the error message is delayed so we can
939 * properly print the icmp error rate that the system was trying to do
940 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
941 * the 'final' error, but it doesn't make sense to solve the printing
942 * delay with more complex code.
943 */
944
945 int
946 badport_bandlim(int which)
947 {
948
949 #define N(a) (sizeof (a) / sizeof (a[0]))
950 static struct rate {
951 const char *type;
952 struct timeval lasttime;
953 int curpps;
954 } rates[BANDLIM_MAX+1] = {
955 { "icmp unreach response" },
956 { "icmp ping response" },
957 { "icmp tstamp response" },
958 { "closed port RST response" },
959 { "open port RST response" },
960 { "icmp6 unreach response" }
961 };
962
963 /*
964 * Return ok status if feature disabled or argument out of range.
965 */
966 if (V_icmplim > 0 && (u_int) which < N(rates)) {
967 struct rate *r = &rates[which];
968 int opps = r->curpps;
969
970 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
971 return -1; /* discard packet */
972 /*
973 * If we've dropped below the threshold after having
974 * rate-limited traffic print the message. This preserves
975 * the previous behaviour at the expense of added complexity.
976 */
977 if (V_icmplim_output && opps > V_icmplim)
978 printf("Limiting %s from %d to %d packets/sec\n",
979 r->type, opps, V_icmplim);
980 }
981 return 0; /* okay to send packet */
982 #undef N
983 }
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