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/8.2/sys/netinet/ip_icmp.c 211542 2010-08-21 11:01:40Z andre $");
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 #include <sys/syslog.h>
46
47 #include <net/if.h>
48 #include <net/if_types.h>
49 #include <net/route.h>
50 #include <net/vnet.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 VNET_DEFINE(struct icmpstat, icmpstat);
80 SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
81 &VNET_NAME(icmpstat), icmpstat, "");
82
83 static VNET_DEFINE(int, icmpmaskrepl) = 0;
84 #define V_icmpmaskrepl VNET(icmpmaskrepl)
85 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
86 &VNET_NAME(icmpmaskrepl), 0,
87 "Reply to ICMP Address Mask Request packets.");
88
89 static VNET_DEFINE(u_int, icmpmaskfake) = 0;
90 #define V_icmpmaskfake VNET(icmpmaskfake)
91 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
92 &VNET_NAME(icmpmaskfake), 0,
93 "Fake reply to ICMP Address Mask Request packets.");
94
95 static VNET_DEFINE(int, drop_redirect) = 0;
96 #define V_drop_redirect VNET(drop_redirect)
97 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
98 &VNET_NAME(drop_redirect), 0,
99 "Ignore ICMP redirects");
100
101 static VNET_DEFINE(int, log_redirect) = 0;
102 #define V_log_redirect VNET(log_redirect)
103 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
104 &VNET_NAME(log_redirect), 0,
105 "Log ICMP redirects to the console");
106
107 static VNET_DEFINE(int, icmplim) = 200;
108 #define V_icmplim VNET(icmplim)
109 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
110 &VNET_NAME(icmplim), 0,
111 "Maximum number of ICMP responses per second");
112
113 static VNET_DEFINE(int, icmplim_output) = 1;
114 #define V_icmplim_output VNET(icmplim_output)
115 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
116 &VNET_NAME(icmplim_output), 0,
117 "Enable rate limiting of ICMP responses");
118
119 static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
120 #define V_reply_src VNET(reply_src)
121 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
122 &VNET_NAME(reply_src), IFNAMSIZ,
123 "icmp reply source for non-local packets.");
124
125 static VNET_DEFINE(int, icmp_rfi) = 0;
126 #define V_icmp_rfi VNET(icmp_rfi)
127 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
128 &VNET_NAME(icmp_rfi), 0,
129 "ICMP reply from incoming interface for non-local packets");
130
131 static VNET_DEFINE(int, icmp_quotelen) = 8;
132 #define V_icmp_quotelen VNET(icmp_quotelen)
133 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
134 &VNET_NAME(icmp_quotelen), 0,
135 "Number of bytes from original packet to quote in ICMP reply");
136
137 /*
138 * ICMP broadcast echo sysctl
139 */
140 static VNET_DEFINE(int, icmpbmcastecho) = 0;
141 #define V_icmpbmcastecho VNET(icmpbmcastecho)
142 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
143 &VNET_NAME(icmpbmcastecho), 0,
144 "");
145
146
147 #ifdef ICMPPRINTFS
148 int icmpprintfs = 0;
149 #endif
150
151 static void icmp_reflect(struct mbuf *);
152 static void icmp_send(struct mbuf *, struct mbuf *);
153
154 extern struct protosw inetsw[];
155
156 /*
157 * Kernel module interface for updating icmpstat. The argument is an index
158 * into icmpstat treated as an array of u_long. While this encodes the
159 * general layout of icmpstat into the caller, it doesn't encode its
160 * location, so that future changes to add, for example, per-CPU stats
161 * support won't cause binary compatibility problems for kernel modules.
162 */
163 void
164 kmod_icmpstat_inc(int statnum)
165 {
166
167 (*((u_long *)&V_icmpstat + statnum))++;
168 }
169
170 /*
171 * Generate an error packet of type error
172 * in response to bad packet ip.
173 */
174 void
175 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
176 {
177 register struct ip *oip = mtod(n, struct ip *), *nip;
178 register unsigned oiphlen = oip->ip_hl << 2;
179 register struct icmp *icp;
180 register struct mbuf *m;
181 unsigned icmplen, icmpelen, nlen;
182
183 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
184 #ifdef ICMPPRINTFS
185 if (icmpprintfs)
186 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
187 #endif
188 if (type != ICMP_REDIRECT)
189 ICMPSTAT_INC(icps_error);
190 /*
191 * Don't send error:
192 * if the original packet was encrypted.
193 * if not the first fragment of message.
194 * in response to a multicast or broadcast packet.
195 * if the old packet protocol was an ICMP error message.
196 */
197 if (n->m_flags & M_DECRYPTED)
198 goto freeit;
199 if (oip->ip_off & ~(IP_MF|IP_DF))
200 goto freeit;
201 if (n->m_flags & (M_BCAST|M_MCAST))
202 goto freeit;
203 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
204 n->m_len >= oiphlen + ICMP_MINLEN &&
205 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
206 ICMPSTAT_INC(icps_oldicmp);
207 goto freeit;
208 }
209 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
210 if (oiphlen + 8 > n->m_len)
211 goto freeit;
212 /*
213 * Calculate length to quote from original packet and
214 * prevent the ICMP mbuf from overflowing.
215 * Unfortunatly this is non-trivial since ip_forward()
216 * sends us truncated packets.
217 */
218 nlen = m_length(n, NULL);
219 if (oip->ip_p == IPPROTO_TCP) {
220 struct tcphdr *th;
221 int tcphlen;
222
223 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
224 n->m_next == NULL)
225 goto stdreply;
226 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
227 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
228 goto freeit;
229 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
230 tcphlen = th->th_off << 2;
231 if (tcphlen < sizeof(struct tcphdr))
232 goto freeit;
233 if (oip->ip_len < oiphlen + tcphlen)
234 goto freeit;
235 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
236 goto stdreply;
237 if (n->m_len < oiphlen + tcphlen &&
238 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
239 goto freeit;
240 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen));
241 } else
242 stdreply: icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen));
243
244 icmplen = min(oiphlen + icmpelen, nlen);
245 if (icmplen < sizeof(struct ip))
246 goto freeit;
247
248 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
249 m = m_gethdr(M_DONTWAIT, MT_DATA);
250 else
251 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
252 if (m == NULL)
253 goto freeit;
254 #ifdef MAC
255 mac_netinet_icmp_reply(n, m);
256 #endif
257 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
258 m_align(m, ICMP_MINLEN + icmplen);
259 m->m_len = ICMP_MINLEN + icmplen;
260
261 /* XXX MRT make the outgoing packet use the same FIB
262 * that was associated with the incoming packet
263 */
264 M_SETFIB(m, M_GETFIB(n));
265 icp = mtod(m, struct icmp *);
266 ICMPSTAT_INC(icps_outhist[type]);
267 icp->icmp_type = type;
268 if (type == ICMP_REDIRECT)
269 icp->icmp_gwaddr.s_addr = dest;
270 else {
271 icp->icmp_void = 0;
272 /*
273 * The following assignments assume an overlay with the
274 * just zeroed icmp_void field.
275 */
276 if (type == ICMP_PARAMPROB) {
277 icp->icmp_pptr = code;
278 code = 0;
279 } else if (type == ICMP_UNREACH &&
280 code == ICMP_UNREACH_NEEDFRAG && mtu) {
281 icp->icmp_nextmtu = htons(mtu);
282 }
283 }
284 icp->icmp_code = code;
285
286 /*
287 * Copy the quotation into ICMP message and
288 * convert quoted IP header back to network representation.
289 */
290 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
291 nip = &icp->icmp_ip;
292 nip->ip_len = htons(nip->ip_len);
293 nip->ip_off = htons(nip->ip_off);
294
295 /*
296 * Set up ICMP message mbuf and copy old IP header (without options
297 * in front of ICMP message.
298 * If the original mbuf was meant to bypass the firewall, the error
299 * reply should bypass as well.
300 */
301 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
302 m->m_data -= sizeof(struct ip);
303 m->m_len += sizeof(struct ip);
304 m->m_pkthdr.len = m->m_len;
305 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
306 nip = mtod(m, struct ip *);
307 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
308 nip->ip_len = m->m_len;
309 nip->ip_v = IPVERSION;
310 nip->ip_hl = 5;
311 nip->ip_p = IPPROTO_ICMP;
312 nip->ip_tos = 0;
313 icmp_reflect(m);
314
315 freeit:
316 m_freem(n);
317 }
318
319 /*
320 * Process a received ICMP message.
321 */
322 void
323 icmp_input(struct mbuf *m, int off)
324 {
325 struct icmp *icp;
326 struct in_ifaddr *ia;
327 struct ip *ip = mtod(m, struct ip *);
328 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
329 int hlen = off;
330 int icmplen = ip->ip_len;
331 int i, code;
332 void (*ctlfunc)(int, struct sockaddr *, void *);
333 int fibnum;
334
335 /*
336 * Locate icmp structure in mbuf, and check
337 * that not corrupted and of at least minimum length.
338 */
339 #ifdef ICMPPRINTFS
340 if (icmpprintfs) {
341 char buf[4 * sizeof "123"];
342 strcpy(buf, inet_ntoa(ip->ip_src));
343 printf("icmp_input from %s to %s, len %d\n",
344 buf, inet_ntoa(ip->ip_dst), icmplen);
345 }
346 #endif
347 if (icmplen < ICMP_MINLEN) {
348 ICMPSTAT_INC(icps_tooshort);
349 goto freeit;
350 }
351 i = hlen + min(icmplen, ICMP_ADVLENMIN);
352 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
353 ICMPSTAT_INC(icps_tooshort);
354 return;
355 }
356 ip = mtod(m, struct ip *);
357 m->m_len -= hlen;
358 m->m_data += hlen;
359 icp = mtod(m, struct icmp *);
360 if (in_cksum(m, icmplen)) {
361 ICMPSTAT_INC(icps_checksum);
362 goto freeit;
363 }
364 m->m_len += hlen;
365 m->m_data -= hlen;
366
367 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
368 /*
369 * Deliver very specific ICMP type only.
370 */
371 switch (icp->icmp_type) {
372 case ICMP_UNREACH:
373 case ICMP_TIMXCEED:
374 break;
375 default:
376 goto freeit;
377 }
378 }
379
380 #ifdef ICMPPRINTFS
381 if (icmpprintfs)
382 printf("icmp_input, type %d code %d\n", icp->icmp_type,
383 icp->icmp_code);
384 #endif
385
386 /*
387 * Message type specific processing.
388 */
389 if (icp->icmp_type > ICMP_MAXTYPE)
390 goto raw;
391
392 /* Initialize */
393 bzero(&icmpsrc, sizeof(icmpsrc));
394 icmpsrc.sin_len = sizeof(struct sockaddr_in);
395 icmpsrc.sin_family = AF_INET;
396 bzero(&icmpdst, sizeof(icmpdst));
397 icmpdst.sin_len = sizeof(struct sockaddr_in);
398 icmpdst.sin_family = AF_INET;
399 bzero(&icmpgw, sizeof(icmpgw));
400 icmpgw.sin_len = sizeof(struct sockaddr_in);
401 icmpgw.sin_family = AF_INET;
402
403 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
404 code = icp->icmp_code;
405 switch (icp->icmp_type) {
406
407 case ICMP_UNREACH:
408 switch (code) {
409 case ICMP_UNREACH_NET:
410 case ICMP_UNREACH_HOST:
411 case ICMP_UNREACH_SRCFAIL:
412 case ICMP_UNREACH_NET_UNKNOWN:
413 case ICMP_UNREACH_HOST_UNKNOWN:
414 case ICMP_UNREACH_ISOLATED:
415 case ICMP_UNREACH_TOSNET:
416 case ICMP_UNREACH_TOSHOST:
417 case ICMP_UNREACH_HOST_PRECEDENCE:
418 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
419 code = PRC_UNREACH_NET;
420 break;
421
422 case ICMP_UNREACH_NEEDFRAG:
423 code = PRC_MSGSIZE;
424 break;
425
426 /*
427 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
428 * Treat subcodes 2,3 as immediate RST
429 */
430 case ICMP_UNREACH_PROTOCOL:
431 case ICMP_UNREACH_PORT:
432 code = PRC_UNREACH_PORT;
433 break;
434
435 case ICMP_UNREACH_NET_PROHIB:
436 case ICMP_UNREACH_HOST_PROHIB:
437 case ICMP_UNREACH_FILTER_PROHIB:
438 code = PRC_UNREACH_ADMIN_PROHIB;
439 break;
440
441 default:
442 goto badcode;
443 }
444 goto deliver;
445
446 case ICMP_TIMXCEED:
447 if (code > 1)
448 goto badcode;
449 code += PRC_TIMXCEED_INTRANS;
450 goto deliver;
451
452 case ICMP_PARAMPROB:
453 if (code > 1)
454 goto badcode;
455 code = PRC_PARAMPROB;
456 goto deliver;
457
458 case ICMP_SOURCEQUENCH:
459 if (code)
460 goto badcode;
461 code = PRC_QUENCH;
462 deliver:
463 /*
464 * Problem with datagram; advise higher level routines.
465 */
466 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
467 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
468 ICMPSTAT_INC(icps_badlen);
469 goto freeit;
470 }
471 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
472 /* Discard ICMP's in response to multicast packets */
473 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
474 goto badcode;
475 #ifdef ICMPPRINTFS
476 if (icmpprintfs)
477 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
478 #endif
479 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
480 /*
481 * XXX if the packet contains [IPv4 AH TCP], we can't make a
482 * notification to TCP layer.
483 */
484 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
485 if (ctlfunc)
486 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
487 (void *)&icp->icmp_ip);
488 break;
489
490 badcode:
491 ICMPSTAT_INC(icps_badcode);
492 break;
493
494 case ICMP_ECHO:
495 if (!V_icmpbmcastecho
496 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
497 ICMPSTAT_INC(icps_bmcastecho);
498 break;
499 }
500 icp->icmp_type = ICMP_ECHOREPLY;
501 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
502 goto freeit;
503 else
504 goto reflect;
505
506 case ICMP_TSTAMP:
507 if (!V_icmpbmcastecho
508 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
509 ICMPSTAT_INC(icps_bmcasttstamp);
510 break;
511 }
512 if (icmplen < ICMP_TSLEN) {
513 ICMPSTAT_INC(icps_badlen);
514 break;
515 }
516 icp->icmp_type = ICMP_TSTAMPREPLY;
517 icp->icmp_rtime = iptime();
518 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
519 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
520 goto freeit;
521 else
522 goto reflect;
523
524 case ICMP_MASKREQ:
525 if (V_icmpmaskrepl == 0)
526 break;
527 /*
528 * We are not able to respond with all ones broadcast
529 * unless we receive it over a point-to-point interface.
530 */
531 if (icmplen < ICMP_MASKLEN)
532 break;
533 switch (ip->ip_dst.s_addr) {
534
535 case INADDR_BROADCAST:
536 case INADDR_ANY:
537 icmpdst.sin_addr = ip->ip_src;
538 break;
539
540 default:
541 icmpdst.sin_addr = ip->ip_dst;
542 }
543 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
544 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
545 if (ia == NULL)
546 break;
547 if (ia->ia_ifp == NULL) {
548 ifa_free(&ia->ia_ifa);
549 break;
550 }
551 icp->icmp_type = ICMP_MASKREPLY;
552 if (V_icmpmaskfake == 0)
553 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
554 else
555 icp->icmp_mask = V_icmpmaskfake;
556 if (ip->ip_src.s_addr == 0) {
557 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
558 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
559 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
560 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
561 }
562 ifa_free(&ia->ia_ifa);
563 reflect:
564 ip->ip_len += hlen; /* since ip_input deducts this */
565 ICMPSTAT_INC(icps_reflect);
566 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
567 icmp_reflect(m);
568 return;
569
570 case ICMP_REDIRECT:
571 if (V_log_redirect) {
572 u_long src, dst, gw;
573
574 src = ntohl(ip->ip_src.s_addr);
575 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
576 gw = ntohl(icp->icmp_gwaddr.s_addr);
577 printf("icmp redirect from %d.%d.%d.%d: "
578 "%d.%d.%d.%d => %d.%d.%d.%d\n",
579 (int)(src >> 24), (int)((src >> 16) & 0xff),
580 (int)((src >> 8) & 0xff), (int)(src & 0xff),
581 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
582 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
583 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
584 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
585 }
586 /*
587 * RFC1812 says we must ignore ICMP redirects if we
588 * are acting as router.
589 */
590 if (V_drop_redirect || V_ipforwarding)
591 break;
592 if (code > 3)
593 goto badcode;
594 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
595 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
596 ICMPSTAT_INC(icps_badlen);
597 break;
598 }
599 /*
600 * Short circuit routing redirects to force
601 * immediate change in the kernel's routing
602 * tables. The message is also handed to anyone
603 * listening on a raw socket (e.g. the routing
604 * daemon for use in updating its tables).
605 */
606 icmpgw.sin_addr = ip->ip_src;
607 icmpdst.sin_addr = icp->icmp_gwaddr;
608 #ifdef ICMPPRINTFS
609 if (icmpprintfs) {
610 char buf[4 * sizeof "123"];
611 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
612
613 printf("redirect dst %s to %s\n",
614 buf, inet_ntoa(icp->icmp_gwaddr));
615 }
616 #endif
617 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
618 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
619 in_rtredirect((struct sockaddr *)&icmpsrc,
620 (struct sockaddr *)&icmpdst,
621 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
622 (struct sockaddr *)&icmpgw, fibnum);
623 }
624 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
625 #ifdef IPSEC
626 key_sa_routechange((struct sockaddr *)&icmpsrc);
627 #endif
628 break;
629
630 /*
631 * No kernel processing for the following;
632 * just fall through to send to raw listener.
633 */
634 case ICMP_ECHOREPLY:
635 case ICMP_ROUTERADVERT:
636 case ICMP_ROUTERSOLICIT:
637 case ICMP_TSTAMPREPLY:
638 case ICMP_IREQREPLY:
639 case ICMP_MASKREPLY:
640 default:
641 break;
642 }
643
644 raw:
645 rip_input(m, off);
646 return;
647
648 freeit:
649 m_freem(m);
650 }
651
652 /*
653 * Reflect the ip packet back to the source
654 */
655 static void
656 icmp_reflect(struct mbuf *m)
657 {
658 struct ip *ip = mtod(m, struct ip *);
659 struct ifaddr *ifa;
660 struct ifnet *ifp;
661 struct in_ifaddr *ia;
662 struct in_addr t;
663 struct mbuf *opts = 0;
664 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
665
666 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
667 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
668 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
669 m_freem(m); /* Bad return address */
670 ICMPSTAT_INC(icps_badaddr);
671 goto done; /* Ip_output() will check for broadcast */
672 }
673
674 t = ip->ip_dst;
675 ip->ip_dst = ip->ip_src;
676
677 /*
678 * Source selection for ICMP replies:
679 *
680 * If the incoming packet was addressed directly to one of our
681 * own addresses, use dst as the src for the reply.
682 */
683 IN_IFADDR_RLOCK();
684 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
685 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
686 t = IA_SIN(ia)->sin_addr;
687 IN_IFADDR_RUNLOCK();
688 goto match;
689 }
690 }
691 IN_IFADDR_RUNLOCK();
692
693 /*
694 * If the incoming packet was addressed to one of our broadcast
695 * addresses, use the first non-broadcast address which corresponds
696 * to the incoming interface.
697 */
698 ifp = m->m_pkthdr.rcvif;
699 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
700 IF_ADDR_LOCK(ifp);
701 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
702 if (ifa->ifa_addr->sa_family != AF_INET)
703 continue;
704 ia = ifatoia(ifa);
705 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
706 t.s_addr) {
707 t = IA_SIN(ia)->sin_addr;
708 IF_ADDR_UNLOCK(ifp);
709 goto match;
710 }
711 }
712 IF_ADDR_UNLOCK(ifp);
713 }
714 /*
715 * If the packet was transiting through us, use the address of
716 * the interface the packet came through in. If that interface
717 * doesn't have a suitable IP address, the normal selection
718 * criteria apply.
719 */
720 if (V_icmp_rfi && ifp != NULL) {
721 IF_ADDR_LOCK(ifp);
722 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
723 if (ifa->ifa_addr->sa_family != AF_INET)
724 continue;
725 ia = ifatoia(ifa);
726 t = IA_SIN(ia)->sin_addr;
727 IF_ADDR_UNLOCK(ifp);
728 goto match;
729 }
730 IF_ADDR_UNLOCK(ifp);
731 }
732 /*
733 * If the incoming packet was not addressed directly to us, use
734 * designated interface for icmp replies specified by sysctl
735 * net.inet.icmp.reply_src (default not set). Otherwise continue
736 * with normal source selection.
737 */
738 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
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 packet was transiting through us, use the address of
752 * the interface that is the closest to the packet source.
753 * When we don't have a route back to the packet source, stop here
754 * and drop the packet.
755 */
756 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
757 if (ia == NULL) {
758 m_freem(m);
759 ICMPSTAT_INC(icps_noroute);
760 goto done;
761 }
762 t = IA_SIN(ia)->sin_addr;
763 ifa_free(&ia->ia_ifa);
764 match:
765 #ifdef MAC
766 mac_netinet_icmp_replyinplace(m);
767 #endif
768 ip->ip_src = t;
769 ip->ip_ttl = V_ip_defttl;
770
771 if (optlen > 0) {
772 register u_char *cp;
773 int opt, cnt;
774 u_int len;
775
776 /*
777 * Retrieve any source routing from the incoming packet;
778 * add on any record-route or timestamp options.
779 */
780 cp = (u_char *) (ip + 1);
781 if ((opts = ip_srcroute(m)) == 0 &&
782 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
783 opts->m_len = sizeof(struct in_addr);
784 mtod(opts, struct in_addr *)->s_addr = 0;
785 }
786 if (opts) {
787 #ifdef ICMPPRINTFS
788 if (icmpprintfs)
789 printf("icmp_reflect optlen %d rt %d => ",
790 optlen, opts->m_len);
791 #endif
792 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
793 opt = cp[IPOPT_OPTVAL];
794 if (opt == IPOPT_EOL)
795 break;
796 if (opt == IPOPT_NOP)
797 len = 1;
798 else {
799 if (cnt < IPOPT_OLEN + sizeof(*cp))
800 break;
801 len = cp[IPOPT_OLEN];
802 if (len < IPOPT_OLEN + sizeof(*cp) ||
803 len > cnt)
804 break;
805 }
806 /*
807 * Should check for overflow, but it "can't happen"
808 */
809 if (opt == IPOPT_RR || opt == IPOPT_TS ||
810 opt == IPOPT_SECURITY) {
811 bcopy((caddr_t)cp,
812 mtod(opts, caddr_t) + opts->m_len, len);
813 opts->m_len += len;
814 }
815 }
816 /* Terminate & pad, if necessary */
817 cnt = opts->m_len % 4;
818 if (cnt) {
819 for (; cnt < 4; cnt++) {
820 *(mtod(opts, caddr_t) + opts->m_len) =
821 IPOPT_EOL;
822 opts->m_len++;
823 }
824 }
825 #ifdef ICMPPRINTFS
826 if (icmpprintfs)
827 printf("%d\n", opts->m_len);
828 #endif
829 }
830 /*
831 * Now strip out original options by copying rest of first
832 * mbuf's data back, and adjust the IP length.
833 */
834 ip->ip_len -= optlen;
835 ip->ip_v = IPVERSION;
836 ip->ip_hl = 5;
837 m->m_len -= optlen;
838 if (m->m_flags & M_PKTHDR)
839 m->m_pkthdr.len -= optlen;
840 optlen += sizeof(struct ip);
841 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
842 (unsigned)(m->m_len - sizeof(struct ip)));
843 }
844 m_tag_delete_nonpersistent(m);
845 m->m_flags &= ~(M_BCAST|M_MCAST);
846 icmp_send(m, opts);
847 done:
848 if (opts)
849 (void)m_free(opts);
850 }
851
852 /*
853 * Send an icmp packet back to the ip level,
854 * after supplying a checksum.
855 */
856 static void
857 icmp_send(struct mbuf *m, struct mbuf *opts)
858 {
859 register struct ip *ip = mtod(m, struct ip *);
860 register int hlen;
861 register struct icmp *icp;
862
863 hlen = ip->ip_hl << 2;
864 m->m_data += hlen;
865 m->m_len -= hlen;
866 icp = mtod(m, struct icmp *);
867 icp->icmp_cksum = 0;
868 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
869 m->m_data -= hlen;
870 m->m_len += hlen;
871 m->m_pkthdr.rcvif = (struct ifnet *)0;
872 #ifdef ICMPPRINTFS
873 if (icmpprintfs) {
874 char buf[4 * sizeof "123"];
875 strcpy(buf, inet_ntoa(ip->ip_dst));
876 printf("icmp_send dst %s src %s\n",
877 buf, inet_ntoa(ip->ip_src));
878 }
879 #endif
880 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
881 }
882
883 /*
884 * Return milliseconds since 00:00 GMT in network format.
885 */
886 uint32_t
887 iptime(void)
888 {
889 struct timeval atv;
890 u_long t;
891
892 getmicrotime(&atv);
893 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
894 return (htonl(t));
895 }
896
897 /*
898 * Return the next larger or smaller MTU plateau (table from RFC 1191)
899 * given current value MTU. If DIR is less than zero, a larger plateau
900 * is returned; otherwise, a smaller value is returned.
901 */
902 int
903 ip_next_mtu(int mtu, int dir)
904 {
905 static int mtutab[] = {
906 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
907 296, 68, 0
908 };
909 int i, size;
910
911 size = (sizeof mtutab) / (sizeof mtutab[0]);
912 if (dir >= 0) {
913 for (i = 0; i < size; i++)
914 if (mtu > mtutab[i])
915 return mtutab[i];
916 } else {
917 for (i = size - 1; i >= 0; i--)
918 if (mtu < mtutab[i])
919 return mtutab[i];
920 if (mtu == mtutab[0])
921 return mtutab[0];
922 }
923 return 0;
924 }
925
926
927 /*
928 * badport_bandlim() - check for ICMP bandwidth limit
929 *
930 * Return 0 if it is ok to send an ICMP error response, -1 if we have
931 * hit our bandwidth limit and it is not ok.
932 *
933 * If icmplim is <= 0, the feature is disabled and 0 is returned.
934 *
935 * For now we separate the TCP and UDP subsystems w/ different 'which'
936 * values. We may eventually remove this separation (and simplify the
937 * code further).
938 *
939 * Note that the printing of the error message is delayed so we can
940 * properly print the icmp error rate that the system was trying to do
941 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
942 * the 'final' error, but it doesn't make sense to solve the printing
943 * delay with more complex code.
944 */
945
946 int
947 badport_bandlim(int which)
948 {
949
950 #define N(a) (sizeof (a) / sizeof (a[0]))
951 static struct rate {
952 const char *type;
953 struct timeval lasttime;
954 int curpps;
955 } rates[BANDLIM_MAX+1] = {
956 { "icmp unreach response" },
957 { "icmp ping response" },
958 { "icmp tstamp response" },
959 { "closed port RST response" },
960 { "open port RST response" },
961 { "icmp6 unreach response" }
962 };
963
964 /*
965 * Return ok status if feature disabled or argument out of range.
966 */
967 if (V_icmplim > 0 && (u_int) which < N(rates)) {
968 struct rate *r = &rates[which];
969 int opps = r->curpps;
970
971 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
972 return -1; /* discard packet */
973 /*
974 * If we've dropped below the threshold after having
975 * rate-limited traffic print the message. This preserves
976 * the previous behaviour at the expense of added complexity.
977 */
978 if (V_icmplim_output && opps > V_icmplim)
979 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
980 r->type, opps, V_icmplim);
981 }
982 return 0; /* okay to send packet */
983 #undef N
984 }
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