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 * 3. 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 * $FreeBSD: src/sys/netinet/ip_icmp.c,v 1.39.2.19 2003/01/24 05:11:34 sam Exp $
31 */
32
33 #include "opt_ipsec.h"
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/mbuf.h>
38 #include <sys/protosw.h>
39 #include <sys/socket.h>
40 #include <sys/socketops.h>
41 #include <sys/time.h>
42 #include <sys/kernel.h>
43 #include <sys/sysctl.h>
44 #include <sys/in_cksum.h>
45
46 #include <machine/stdarg.h>
47
48 #include <net/if.h>
49 #include <net/if_types.h>
50 #include <net/route.h>
51
52 #define _IP_VHL
53 #include <netinet/in.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/icmp_var.h>
60
61 #ifdef IPSEC
62 #include <netinet6/ipsec.h>
63 #include <netproto/key/key.h>
64 #endif
65
66 #ifdef FAST_IPSEC
67 #include <netproto/ipsec/ipsec.h>
68 #include <netproto/ipsec/key.h>
69 #define IPSEC
70 #endif
71
72 /*
73 * ICMP routines: error generation, receive packet processing, and
74 * routines to turnaround packets back to the originator, and
75 * host table maintenance routines.
76 */
77
78 struct icmpstat icmpstat;
79 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
80 &icmpstat, icmpstat, "ICMP statistics");
81
82 static int icmpmaskrepl = 0;
83 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
84 &icmpmaskrepl, 0, "Allow replies to netmask requests");
85
86 static int drop_redirect = 0;
87 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
88 &drop_redirect, 0, "Ignore ICMP redirects");
89
90 static int log_redirect = 0;
91 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
92 &log_redirect, 0, "Enable output about ICMP redirects");
93
94 static int discard_sourcequench = 1;
95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, discard_sourcequench, CTLFLAG_RW,
96 &discard_sourcequench, 0, "Discard ICMP Source Quench");
97
98 #ifdef ICMP_BANDLIM
99
100 /*
101 * ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl
102 * variable content is -1 and read-only.
103 */
104
105 static int icmplim = 200;
106 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
107 &icmplim, 0, "ICMP bandwidth limit");
108 #else
109
110 static int icmplim = -1;
111 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD,
112 &icmplim, 0, "ICMP bandwidth limit");
113
114 #endif
115
116 static int icmplim_output = 0;
117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
118 &icmplim_output, 0, "Enable output about ICMP bandwidth limits");
119
120 /*
121 * ICMP broadcast echo sysctl
122 */
123
124 static int icmpbmcastecho = 0;
125 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
126 &icmpbmcastecho, 0, "");
127
128 static char icmp_reply_src[IFNAMSIZ];
129 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
130 icmp_reply_src, IFNAMSIZ, "icmp reply source for non-local packets.");
131
132 static int icmp_rfi;
133 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
134 &icmp_rfi, 0, "ICMP reply from incoming interface for "
135 "non-local packets");
136
137 #ifdef ICMPPRINTFS
138 int icmpprintfs = 0;
139 #endif
140
141 static void icmp_reflect (struct mbuf *);
142 static void icmp_send (struct mbuf *, struct mbuf *, struct route *);
143
144 extern struct protosw inetsw[];
145
146 /*
147 * Generate an error packet of type error
148 * in response to bad packet ip.
149 */
150 void
151 icmp_error(struct mbuf *n, int type, int code, n_long dest, int destmtu)
152 {
153 struct ip *oip = mtod(n, struct ip *), *nip;
154 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
155 struct icmp *icp;
156 struct mbuf *m;
157 unsigned icmplen;
158
159 #ifdef ICMPPRINTFS
160 if (icmpprintfs)
161 kprintf("icmp_error(%p, %d, %d)\n", oip, type, code);
162 #endif
163 if (type != ICMP_REDIRECT)
164 icmpstat.icps_error++;
165 /*
166 * Don't send error if the original packet was encrypted.
167 * Don't send error if not the first fragment of message.
168 * Don't error if the old packet protocol was ICMP
169 * error message, only known informational types.
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 (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
176 n->m_len >= oiplen + ICMP_MINLEN &&
177 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
178 icmpstat.icps_oldicmp++;
179 goto freeit;
180 }
181 /* Don't send error in response to a multicast or broadcast packet */
182 if (n->m_flags & (M_BCAST|M_MCAST))
183 goto freeit;
184 /*
185 * First, formulate icmp message
186 */
187 m = m_gethdr(MB_DONTWAIT, MT_HEADER);
188 if (m == NULL)
189 goto freeit;
190 icmplen = min(oiplen + 8, oip->ip_len);
191 if (icmplen < sizeof(struct ip))
192 panic("icmp_error: bad length");
193 m->m_len = icmplen + ICMP_MINLEN;
194 MH_ALIGN(m, m->m_len);
195 icp = mtod(m, struct icmp *);
196 if ((u_int)type > ICMP_MAXTYPE)
197 panic("icmp_error");
198 icmpstat.icps_outhist[type]++;
199 icp->icmp_type = type;
200 if (type == ICMP_REDIRECT)
201 icp->icmp_gwaddr.s_addr = dest;
202 else {
203 icp->icmp_void = 0;
204 /*
205 * The following assignments assume an overlay with the
206 * zeroed icmp_void field.
207 */
208 if (type == ICMP_PARAMPROB) {
209 icp->icmp_pptr = code;
210 code = 0;
211 } else if (type == ICMP_UNREACH &&
212 code == ICMP_UNREACH_NEEDFRAG && destmtu) {
213 icp->icmp_nextmtu = htons(destmtu);
214 }
215 }
216
217 icp->icmp_code = code;
218 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
219 nip = &icp->icmp_ip;
220
221 /*
222 * Convert fields to network representation.
223 */
224 nip->ip_len = htons(nip->ip_len);
225 nip->ip_off = htons(nip->ip_off);
226
227 /*
228 * Now, copy old ip header (without options)
229 * in front of icmp message.
230 */
231 if (m->m_data - sizeof(struct ip) < m->m_pktdat)
232 panic("icmp len");
233 m->m_data -= sizeof(struct ip);
234 m->m_len += sizeof(struct ip);
235 m->m_pkthdr.len = m->m_len;
236 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
237 nip = mtod(m, struct ip *);
238 bcopy(oip, nip, sizeof(struct ip));
239 nip->ip_len = m->m_len;
240 nip->ip_vhl = IP_VHL_BORING;
241 nip->ip_p = IPPROTO_ICMP;
242 nip->ip_tos = 0;
243 m->m_pkthdr.fw_flags |= n->m_pkthdr.fw_flags & FW_MBUF_GENERATED;
244 icmp_reflect(m);
245
246 freeit:
247 m_freem(n);
248 }
249
250 /*
251 * Process a received ICMP message.
252 */
253 int
254 icmp_input(struct mbuf **mp, int *offp, int proto)
255 {
256 struct sockaddr_in icmpsrc = { sizeof(struct sockaddr_in), AF_INET };
257 struct sockaddr_in icmpdst = { sizeof(struct sockaddr_in), AF_INET };
258 struct sockaddr_in icmpgw = { sizeof(struct sockaddr_in), AF_INET };
259 struct icmp *icp;
260 struct in_ifaddr *ia;
261 struct mbuf *m = *mp;
262 struct ip *ip = mtod(m, struct ip *);
263 int icmplen = ip->ip_len;
264 int i, hlen;
265 int code;
266
267 *mp = NULL;
268 hlen = *offp;
269
270 /*
271 * Locate icmp structure in mbuf, and check
272 * that not corrupted and of at least minimum length.
273 */
274 #ifdef ICMPPRINTFS
275 if (icmpprintfs) {
276 char buf[sizeof "aaa.bbb.ccc.ddd"];
277
278 strcpy(buf, inet_ntoa(ip->ip_src));
279 kprintf("icmp_input from %s to %s, len %d\n",
280 buf, inet_ntoa(ip->ip_dst), icmplen);
281 }
282 #endif
283 if (icmplen < ICMP_MINLEN) {
284 icmpstat.icps_tooshort++;
285 goto freeit;
286 }
287 i = hlen + min(icmplen, ICMP_ADVLENMIN);
288 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
289 icmpstat.icps_tooshort++;
290 return(IPPROTO_DONE);
291 }
292 ip = mtod(m, struct ip *);
293 m->m_len -= hlen;
294 m->m_data += hlen;
295 icp = mtod(m, struct icmp *);
296 if (in_cksum(m, icmplen)) {
297 icmpstat.icps_checksum++;
298 goto freeit;
299 }
300 m->m_len += hlen;
301 m->m_data -= hlen;
302
303 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
304 /*
305 * Deliver very specific ICMP type only.
306 */
307 switch (icp->icmp_type) {
308 case ICMP_UNREACH:
309 case ICMP_TIMXCEED:
310 break;
311 default:
312 goto freeit;
313 }
314 }
315
316 #ifdef ICMPPRINTFS
317 if (icmpprintfs)
318 kprintf("icmp_input, type %d code %d\n", icp->icmp_type,
319 icp->icmp_code);
320 #endif
321
322 /*
323 * Message type specific processing.
324 */
325 if (icp->icmp_type > ICMP_MAXTYPE)
326 goto raw;
327 icmpstat.icps_inhist[icp->icmp_type]++;
328 code = icp->icmp_code;
329 switch (icp->icmp_type) {
330
331 case ICMP_UNREACH:
332 switch (code) {
333 case ICMP_UNREACH_NET:
334 case ICMP_UNREACH_HOST:
335 case ICMP_UNREACH_SRCFAIL:
336 case ICMP_UNREACH_NET_UNKNOWN:
337 case ICMP_UNREACH_HOST_UNKNOWN:
338 case ICMP_UNREACH_ISOLATED:
339 case ICMP_UNREACH_TOSNET:
340 case ICMP_UNREACH_TOSHOST:
341 case ICMP_UNREACH_HOST_PRECEDENCE:
342 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
343 code = PRC_UNREACH_NET;
344 break;
345
346 case ICMP_UNREACH_NEEDFRAG:
347 code = PRC_MSGSIZE;
348 break;
349
350 /*
351 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
352 * Treat subcodes 2,3 as immediate RST
353 */
354 case ICMP_UNREACH_PROTOCOL:
355 case ICMP_UNREACH_PORT:
356 code = PRC_UNREACH_PORT;
357 break;
358
359 case ICMP_UNREACH_NET_PROHIB:
360 case ICMP_UNREACH_HOST_PROHIB:
361 case ICMP_UNREACH_FILTER_PROHIB:
362 code = PRC_UNREACH_ADMIN_PROHIB;
363 break;
364
365 default:
366 goto badcode;
367 }
368 goto deliver;
369
370 case ICMP_TIMXCEED:
371 if (code > 1)
372 goto badcode;
373 code += PRC_TIMXCEED_INTRANS;
374 goto deliver;
375
376 case ICMP_PARAMPROB:
377 if (code > 1)
378 goto badcode;
379 code = PRC_PARAMPROB;
380 goto deliver;
381
382 case ICMP_SOURCEQUENCH:
383 if (code)
384 goto badcode;
385 if (discard_sourcequench)
386 break;
387 code = PRC_QUENCH;
388 deliver:
389 /*
390 * Problem with datagram; advise higher level routines.
391 */
392 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
393 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
394 icmpstat.icps_badlen++;
395 goto freeit;
396 }
397 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
398 /* Discard ICMP's in response to multicast packets */
399 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
400 goto badcode;
401 #ifdef ICMPPRINTFS
402 if (icmpprintfs)
403 kprintf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
404 #endif
405 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
406 #if 1
407 /*
408 * MTU discovery:
409 * If we got a needfrag and there is a host route to the
410 * original destination, and the MTU is not locked, then
411 * set the MTU in the route to the suggested new value
412 * (if given) and then notify as usual. The ULPs will
413 * notice that the MTU has changed and adapt accordingly.
414 * If no new MTU was suggested, then we guess a new one
415 * less than the current value. If the new MTU is
416 * unreasonably small (arbitrarily set at 296), then
417 * we reset the MTU to the interface value and enable the
418 * lock bit, indicating that we are no longer doing MTU
419 * discovery.
420 */
421 if (code == PRC_MSGSIZE) {
422 struct rtentry *rt;
423 int mtu;
424
425 rt = rtpurelookup((struct sockaddr *)&icmpsrc);
426 if (rt != NULL && (rt->rt_flags & RTF_HOST) &&
427 !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
428 mtu = ntohs(icp->icmp_nextmtu);
429 if (!mtu)
430 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
431 1);
432 #ifdef DEBUG_MTUDISC
433 kprintf("MTU for %s reduced to %d\n",
434 inet_ntoa(icmpsrc.sin_addr), mtu);
435 #endif
436 if (mtu < 296) {
437 /* rt->rt_rmx.rmx_mtu =
438 rt->rt_ifp->if_mtu; */
439 rt->rt_rmx.rmx_locks |= RTV_MTU;
440 } else if (rt->rt_rmx.rmx_mtu > mtu) {
441 rt->rt_rmx.rmx_mtu = mtu;
442 }
443 }
444 if (rt != NULL)
445 --rt->rt_refcnt;
446 }
447 #endif
448 /*
449 * XXX if the packet contains [IPv4 AH TCP], we can't make a
450 * notification to TCP layer.
451 */
452 so_pru_ctlinput(
453 &inetsw[ip_protox[icp->icmp_ip.ip_p]],
454 code, (struct sockaddr *)&icmpsrc, &icp->icmp_ip);
455 break;
456
457 badcode:
458 icmpstat.icps_badcode++;
459 break;
460
461 case ICMP_ECHO:
462 if (!icmpbmcastecho
463 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
464 icmpstat.icps_bmcastecho++;
465 break;
466 }
467 icp->icmp_type = ICMP_ECHOREPLY;
468 #ifdef ICMP_BANDLIM
469 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
470 goto freeit;
471 else
472 #endif
473 goto reflect;
474
475 case ICMP_TSTAMP:
476 if (!icmpbmcastecho
477 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
478 icmpstat.icps_bmcasttstamp++;
479 break;
480 }
481 if (icmplen < ICMP_TSLEN) {
482 icmpstat.icps_badlen++;
483 break;
484 }
485 icp->icmp_type = ICMP_TSTAMPREPLY;
486 icp->icmp_rtime = iptime();
487 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
488 #ifdef ICMP_BANDLIM
489 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
490 goto freeit;
491 else
492 #endif
493 goto reflect;
494
495 case ICMP_MASKREQ:
496 if (icmpmaskrepl == 0)
497 break;
498 /*
499 * We are not able to respond with all ones broadcast
500 * unless we receive it over a point-to-point interface.
501 */
502 if (icmplen < ICMP_MASKLEN)
503 break;
504 switch (ip->ip_dst.s_addr) {
505
506 case INADDR_BROADCAST:
507 case INADDR_ANY:
508 icmpdst.sin_addr = ip->ip_src;
509 break;
510
511 default:
512 icmpdst.sin_addr = ip->ip_dst;
513 }
514 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
515 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
516 if (ia == NULL)
517 break;
518 if (ia->ia_ifp == 0)
519 break;
520 icp->icmp_type = ICMP_MASKREPLY;
521 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
522 if (ip->ip_src.s_addr == 0) {
523 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
524 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
525 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
526 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
527 }
528 reflect:
529 ip->ip_len += hlen; /* since ip_input deducts this */
530 icmpstat.icps_reflect++;
531 icmpstat.icps_outhist[icp->icmp_type]++;
532 icmp_reflect(m);
533 return(IPPROTO_DONE);
534
535 case ICMP_REDIRECT:
536 if (log_redirect) {
537 u_long src, dst, gw;
538
539 src = ntohl(ip->ip_src.s_addr);
540 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
541 gw = ntohl(icp->icmp_gwaddr.s_addr);
542 kprintf("icmp redirect from %d.%d.%d.%d: "
543 "%d.%d.%d.%d => %d.%d.%d.%d\n",
544 (int)(src >> 24), (int)((src >> 16) & 0xff),
545 (int)((src >> 8) & 0xff), (int)(src & 0xff),
546 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
547 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
548 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
549 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
550 }
551 if (drop_redirect)
552 break;
553 if (code > 3)
554 goto badcode;
555 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
556 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
557 icmpstat.icps_badlen++;
558 break;
559 }
560 /*
561 * Short circuit routing redirects to force
562 * immediate change in the kernel's routing
563 * tables. The message is also handed to anyone
564 * listening on a raw socket (e.g. the routing
565 * daemon for use in updating its tables).
566 */
567 icmpgw.sin_addr = ip->ip_src;
568 icmpdst.sin_addr = icp->icmp_gwaddr;
569 #ifdef ICMPPRINTFS
570 if (icmpprintfs) {
571 char buf[sizeof "aaa.bbb.ccc.ddd"];
572
573 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
574 kprintf("redirect dst %s to %s\n",
575 buf, inet_ntoa(icp->icmp_gwaddr));
576 }
577 #endif
578 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
579 rtredirect((struct sockaddr *)&icmpsrc,
580 (struct sockaddr *)&icmpdst,
581 NULL, RTF_GATEWAY | RTF_HOST,
582 (struct sockaddr *)&icmpgw);
583 kpfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
584 #ifdef IPSEC
585 key_sa_routechange((struct sockaddr *)&icmpsrc);
586 #endif
587 break;
588
589 /*
590 * No kernel processing for the following;
591 * just fall through to send to raw listener.
592 */
593 case ICMP_ECHOREPLY:
594 case ICMP_ROUTERADVERT:
595 case ICMP_ROUTERSOLICIT:
596 case ICMP_TSTAMPREPLY:
597 case ICMP_IREQREPLY:
598 case ICMP_MASKREPLY:
599 default:
600 break;
601 }
602
603 raw:
604 *mp = m;
605 rip_input(mp, offp, proto);
606 return(IPPROTO_DONE);
607
608 freeit:
609 m_freem(m);
610 return(IPPROTO_DONE);
611 }
612
613 /*
614 * Reflect the ip packet back to the source
615 */
616 static void
617 icmp_reflect(struct mbuf *m)
618 {
619 struct ip *ip = mtod(m, struct ip *);
620 struct in_ifaddr *ia;
621 struct in_ifaddr_container *iac;
622 struct ifaddr_container *ifac;
623 struct ifnet *ifp;
624 struct in_addr t;
625 struct mbuf *opts = NULL;
626 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
627 struct route *ro = NULL, rt;
628
629 if (!in_canforward(ip->ip_src) &&
630 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
631 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
632 m_freem(m); /* Bad return address */
633 icmpstat.icps_badaddr++;
634 goto done; /* Ip_output() will check for broadcast */
635 }
636 t = ip->ip_dst;
637 ip->ip_dst = ip->ip_src;
638
639 ro = &rt;
640 bzero(ro, sizeof *ro);
641
642 /*
643 * If the incoming packet was addressed directly to us,
644 * use dst as the src for the reply. Otherwise (broadcast
645 * or anonymous), use the address which corresponds
646 * to the incoming interface.
647 */
648 ia = NULL;
649 LIST_FOREACH(iac, INADDR_HASH(t.s_addr), ia_hash) {
650 if (t.s_addr == IA_SIN(iac->ia)->sin_addr.s_addr) {
651 ia = iac->ia;
652 goto match;
653 }
654 }
655 ifp = m->m_pkthdr.rcvif;
656 if (ifp != NULL && (ifp->if_flags & IFF_BROADCAST)) {
657 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
658 struct ifaddr *ifa = ifac->ifa;
659
660 if (ifa->ifa_addr->sa_family != AF_INET)
661 continue;
662 ia = ifatoia(ifa);
663 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
664 t.s_addr)
665 goto match;
666 }
667 }
668 /*
669 * If the packet was transiting through us, use the address of
670 * the interface the packet came through in. If that interface
671 * doesn't have a suitable IP address, the normal selection
672 * criteria apply.
673 */
674 if (icmp_rfi && ifp != NULL) {
675 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
676 struct ifaddr *ifa = ifac->ifa;
677
678 if (ifa->ifa_addr->sa_family != AF_INET)
679 continue;
680 ia = ifatoia(ifa);
681 goto match;
682 }
683 }
684 /*
685 * If the incoming packet was not addressed directly to us, use
686 * designated interface for icmp replies specified by sysctl
687 * net.inet.icmp.reply_src (default not set). Otherwise continue
688 * with normal source selection.
689 */
690 if (icmp_reply_src[0] != '\0' && (ifp = ifunit(icmp_reply_src))) {
691 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
692 struct ifaddr *ifa = ifac->ifa;
693
694 if (ifa->ifa_addr->sa_family != AF_INET)
695 continue;
696 ia = ifatoia(ifa);
697 goto match;
698 }
699 }
700 /*
701 * If the packet was transiting through us, use the address of
702 * the interface that is the closest to the packet source.
703 * When we don't have a route back to the packet source, stop here
704 * and drop the packet.
705 */
706 ia = ip_rtaddr(ip->ip_dst, ro);
707 if (ia == NULL) {
708 m_freem(m);
709 icmpstat.icps_noroute++;
710 goto done;
711 }
712 match:
713 t = IA_SIN(ia)->sin_addr;
714 ip->ip_src = t;
715 ip->ip_ttl = ip_defttl;
716
717 if (optlen > 0) {
718 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)) == NULL &&
728 (opts = m_gethdr(MB_DONTWAIT, MT_HEADER))) {
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 kprintf("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
754 * "can't happen".
755 */
756 if (opt == IPOPT_RR || opt == IPOPT_TS ||
757 opt == IPOPT_SECURITY) {
758 bcopy(cp,
759 mtod(opts, caddr_t) + opts->m_len,
760 len);
761 opts->m_len += len;
762 }
763 }
764 /* Terminate & pad, if necessary */
765 cnt = opts->m_len % 4;
766 if (cnt) {
767 for (; cnt < 4; cnt++) {
768 *(mtod(opts, caddr_t) + opts->m_len) =
769 IPOPT_EOL;
770 opts->m_len++;
771 }
772 }
773 #ifdef ICMPPRINTFS
774 if (icmpprintfs)
775 kprintf("%d\n", opts->m_len);
776 #endif
777 }
778 /*
779 * Now strip out original options by copying rest of first
780 * mbuf's data back, and adjust the IP length.
781 */
782 ip->ip_len -= optlen;
783 ip->ip_vhl = IP_VHL_BORING;
784 m->m_len -= optlen;
785 if (m->m_flags & M_PKTHDR)
786 m->m_pkthdr.len -= optlen;
787 optlen += sizeof(struct ip);
788 bcopy((caddr_t)ip + optlen, ip + 1,
789 m->m_len - sizeof(struct ip));
790 }
791 m->m_pkthdr.fw_flags &= FW_MBUF_GENERATED;
792 m->m_flags &= ~(M_BCAST|M_MCAST);
793 icmp_send(m, opts, ro);
794 done:
795 if (opts)
796 m_free(opts);
797 if (ro && ro->ro_rt)
798 RTFREE(ro->ro_rt);
799 }
800
801 /*
802 * Send an icmp packet back to the ip level,
803 * after supplying a checksum.
804 */
805 static void
806 icmp_send(struct mbuf *m, struct mbuf *opts, struct route *rt)
807 {
808 struct ip *ip = mtod(m, struct ip *);
809 struct icmp *icp;
810 int hlen;
811
812 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
813 m->m_data += hlen;
814 m->m_len -= hlen;
815 icp = mtod(m, struct icmp *);
816 icp->icmp_cksum = 0;
817 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
818 m->m_data -= hlen;
819 m->m_len += hlen;
820 m->m_pkthdr.rcvif = NULL;
821 #ifdef ICMPPRINTFS
822 if (icmpprintfs) {
823 char buf[sizeof "aaa.bbb.ccc.ddd"];
824
825 strcpy(buf, inet_ntoa(ip->ip_dst));
826 kprintf("icmp_send dst %s src %s\n", buf, inet_ntoa(ip->ip_src));
827 }
828 #endif
829 ip_output(m, opts, rt, 0, NULL, NULL);
830 }
831
832 n_time
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 #if 1
844 /*
845 * Return the next larger or smaller MTU plateau (table from RFC 1191)
846 * given current value MTU. If DIR is less than zero, a larger plateau
847 * is returned; otherwise, a smaller value is returned.
848 */
849 int
850 ip_next_mtu(int mtu, int dir)
851 {
852 static int mtutab[] = {
853 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
854 68, 0
855 };
856 int i;
857
858 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
859 if (mtu >= mtutab[i])
860 break;
861 }
862
863 if (dir < 0) {
864 if (i == 0) {
865 return 0;
866 } else {
867 return mtutab[i - 1];
868 }
869 } else {
870 if (mtutab[i] == 0) {
871 return 0;
872 } else if(mtu > mtutab[i]) {
873 return mtutab[i];
874 } else {
875 return mtutab[i + 1];
876 }
877 }
878 }
879 #endif
880
881 #ifdef ICMP_BANDLIM
882 /*
883 * badport_bandlim() - check for ICMP bandwidth limit
884 *
885 * Return 0 if it is ok to send an ICMP error response, -1 if we have
886 * hit our bandwidth limit and it is not ok.
887 *
888 * If icmplim is <= 0, the feature is disabled and 0 is returned.
889 *
890 * For now we separate the TCP and UDP subsystems w/ different 'which'
891 * values. We may eventually remove this separation (and simplify the
892 * code further).
893 *
894 * Note that the printing of the error message is delayed so we can
895 * properly print the icmp error rate that the system was trying to do
896 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
897 * the 'final' error, but it doesn't make sense to solve the printing
898 * delay with more complex code.
899 */
900 int
901 badport_bandlim(int which)
902 {
903 static int lticks[BANDLIM_MAX + 1];
904 static int lpackets[BANDLIM_MAX + 1];
905 int dticks;
906 const char *bandlimittype[] = {
907 "Limiting icmp unreach response",
908 "Limiting icmp ping response",
909 "Limiting icmp tstamp response",
910 "Limiting closed port RST response",
911 "Limiting open port RST response"
912 };
913
914 /*
915 * Return ok status if feature disabled or argument out of
916 * ranage.
917 */
918
919 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0)
920 return(0);
921 dticks = ticks - lticks[which];
922
923 /*
924 * reset stats when cumulative dt exceeds one second.
925 */
926
927 if ((unsigned int)dticks > hz) {
928 if (lpackets[which] > icmplim && icmplim_output) {
929 kprintf("%s from %d to %d packets per second\n",
930 bandlimittype[which],
931 lpackets[which],
932 icmplim
933 );
934 }
935 lticks[which] = ticks;
936 lpackets[which] = 0;
937 }
938
939 /*
940 * bump packet count
941 */
942
943 if (++lpackets[which] > icmplim) {
944 return(-1);
945 }
946 return(0);
947 }
948 #endif
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