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/11.1/sys/netinet/ip_icmp.c 315456 2017-03-17 14:54:10Z vangyzen $");
34
35 #include "opt_inet.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/lock.h>
45 #include <sys/rmlock.h>
46 #include <sys/sysctl.h>
47 #include <sys/syslog.h>
48
49 #include <net/if.h>
50 #include <net/if_var.h>
51 #include <net/if_types.h>
52 #include <net/route.h>
53 #include <net/vnet.h>
54
55 #include <netinet/in.h>
56 #include <netinet/in_fib.h>
57 #include <netinet/in_pcb.h>
58 #include <netinet/in_systm.h>
59 #include <netinet/in_var.h>
60 #include <netinet/ip.h>
61 #include <netinet/ip_icmp.h>
62 #include <netinet/ip_var.h>
63 #include <netinet/ip_options.h>
64 #include <netinet/sctp.h>
65 #include <netinet/tcp.h>
66 #include <netinet/tcp_var.h>
67 #include <netinet/tcpip.h>
68 #include <netinet/icmp_var.h>
69
70 #ifdef INET
71
72 #include <machine/in_cksum.h>
73
74 #include <security/mac/mac_framework.h>
75 #endif /* INET */
76
77 /*
78 * ICMP routines: error generation, receive packet processing, and
79 * routines to turnaround packets back to the originator, and
80 * host table maintenance routines.
81 */
82 static VNET_DEFINE(int, icmplim) = 200;
83 #define V_icmplim VNET(icmplim)
84 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW,
85 &VNET_NAME(icmplim), 0,
86 "Maximum number of ICMP responses per second");
87
88 static VNET_DEFINE(int, icmplim_output) = 1;
89 #define V_icmplim_output VNET(icmplim_output)
90 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW,
91 &VNET_NAME(icmplim_output), 0,
92 "Enable logging of ICMP response rate limiting");
93
94 #ifdef INET
95 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat);
96 VNET_PCPUSTAT_SYSINIT(icmpstat);
97 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat,
98 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)");
99
100 #ifdef VIMAGE
101 VNET_PCPUSTAT_SYSUNINIT(icmpstat);
102 #endif /* VIMAGE */
103
104 static VNET_DEFINE(int, icmpmaskrepl) = 0;
105 #define V_icmpmaskrepl VNET(icmpmaskrepl)
106 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW,
107 &VNET_NAME(icmpmaskrepl), 0,
108 "Reply to ICMP Address Mask Request packets");
109
110 static VNET_DEFINE(u_int, icmpmaskfake) = 0;
111 #define V_icmpmaskfake VNET(icmpmaskfake)
112 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW,
113 &VNET_NAME(icmpmaskfake), 0,
114 "Fake reply to ICMP Address Mask Request packets");
115
116 VNET_DEFINE(int, drop_redirect) = 0;
117 #define V_drop_redirect VNET(drop_redirect)
118 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW,
119 &VNET_NAME(drop_redirect), 0,
120 "Ignore ICMP redirects");
121
122 static VNET_DEFINE(int, log_redirect) = 0;
123 #define V_log_redirect VNET(log_redirect)
124 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW,
125 &VNET_NAME(log_redirect), 0,
126 "Log ICMP redirects to the console");
127
128 static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
129 #define V_reply_src VNET(reply_src)
130 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW,
131 &VNET_NAME(reply_src), IFNAMSIZ,
132 "ICMP reply source for non-local packets");
133
134 static VNET_DEFINE(int, icmp_rfi) = 0;
135 #define V_icmp_rfi VNET(icmp_rfi)
136 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW,
137 &VNET_NAME(icmp_rfi), 0,
138 "ICMP reply from incoming interface for non-local packets");
139
140 static VNET_DEFINE(int, icmp_quotelen) = 8;
141 #define V_icmp_quotelen VNET(icmp_quotelen)
142 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW,
143 &VNET_NAME(icmp_quotelen), 0,
144 "Number of bytes from original packet to quote in ICMP reply");
145
146 static VNET_DEFINE(int, icmpbmcastecho) = 0;
147 #define V_icmpbmcastecho VNET(icmpbmcastecho)
148 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW,
149 &VNET_NAME(icmpbmcastecho), 0,
150 "Reply to multicast ICMP Echo Request and Timestamp packets");
151
152 static VNET_DEFINE(int, icmptstamprepl) = 1;
153 #define V_icmptstamprepl VNET(icmptstamprepl)
154 SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_RW,
155 &VNET_NAME(icmptstamprepl), 0,
156 "Respond to ICMP Timestamp packets");
157
158 #ifdef ICMPPRINTFS
159 int icmpprintfs = 0;
160 #endif
161
162 static void icmp_reflect(struct mbuf *);
163 static void icmp_send(struct mbuf *, struct mbuf *);
164
165 extern struct protosw inetsw[];
166
167 /*
168 * Kernel module interface for updating icmpstat. The argument is an index
169 * into icmpstat treated as an array of u_long. While this encodes the
170 * general layout of icmpstat into the caller, it doesn't encode its
171 * location, so that future changes to add, for example, per-CPU stats
172 * support won't cause binary compatibility problems for kernel modules.
173 */
174 void
175 kmod_icmpstat_inc(int statnum)
176 {
177
178 counter_u64_add(VNET(icmpstat)[statnum], 1);
179 }
180
181 /*
182 * Generate an error packet of type error
183 * in response to bad packet ip.
184 */
185 void
186 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
187 {
188 register struct ip *oip = mtod(n, struct ip *), *nip;
189 register unsigned oiphlen = oip->ip_hl << 2;
190 register struct icmp *icp;
191 register struct mbuf *m;
192 unsigned icmplen, icmpelen, nlen;
193
194 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
195 #ifdef ICMPPRINTFS
196 if (icmpprintfs)
197 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
198 #endif
199 if (type != ICMP_REDIRECT)
200 ICMPSTAT_INC(icps_error);
201 /*
202 * Don't send error:
203 * if the original packet was encrypted.
204 * if not the first fragment of message.
205 * in response to a multicast or broadcast packet.
206 * if the old packet protocol was an ICMP error message.
207 */
208 if (n->m_flags & M_DECRYPTED)
209 goto freeit;
210 if (oip->ip_off & htons(~(IP_MF|IP_DF)))
211 goto freeit;
212 if (n->m_flags & (M_BCAST|M_MCAST))
213 goto freeit;
214 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
215 n->m_len >= oiphlen + ICMP_MINLEN &&
216 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
217 ICMPSTAT_INC(icps_oldicmp);
218 goto freeit;
219 }
220 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
221 if (oiphlen + 8 > n->m_len)
222 goto freeit;
223 /*
224 * Calculate length to quote from original packet and
225 * prevent the ICMP mbuf from overflowing.
226 * Unfortunately this is non-trivial since ip_forward()
227 * sends us truncated packets.
228 */
229 nlen = m_length(n, NULL);
230 if (oip->ip_p == IPPROTO_TCP) {
231 struct tcphdr *th;
232 int tcphlen;
233
234 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
235 n->m_next == NULL)
236 goto stdreply;
237 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
238 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
239 goto freeit;
240 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
241 tcphlen = th->th_off << 2;
242 if (tcphlen < sizeof(struct tcphdr))
243 goto freeit;
244 if (ntohs(oip->ip_len) < oiphlen + tcphlen)
245 goto freeit;
246 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
247 goto stdreply;
248 if (n->m_len < oiphlen + tcphlen &&
249 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
250 goto freeit;
251 icmpelen = max(tcphlen, min(V_icmp_quotelen,
252 ntohs(oip->ip_len) - oiphlen));
253 } else if (oip->ip_p == IPPROTO_SCTP) {
254 struct sctphdr *sh;
255 struct sctp_chunkhdr *ch;
256
257 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr))
258 goto stdreply;
259 if (oiphlen + sizeof(struct sctphdr) > n->m_len &&
260 n->m_next == NULL)
261 goto stdreply;
262 if (n->m_len < oiphlen + sizeof(struct sctphdr) &&
263 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL)
264 goto freeit;
265 icmpelen = max(sizeof(struct sctphdr),
266 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
267 sh = (struct sctphdr *)((caddr_t)oip + oiphlen);
268 if (ntohl(sh->v_tag) == 0 &&
269 ntohs(oip->ip_len) >= oiphlen + sizeof(struct sctphdr) + 8 &&
270 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 ||
271 n->m_next != NULL)) {
272 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 &&
273 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr) + 8)) == NULL)
274 goto freeit;
275 ch = (struct sctp_chunkhdr *)(sh + 1);
276 if (ch->chunk_type == SCTP_INITIATION) {
277 icmpelen = max(sizeof(struct sctphdr) + 8,
278 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
279 }
280 }
281 } else
282 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
283
284 icmplen = min(oiphlen + icmpelen, nlen);
285 if (icmplen < sizeof(struct ip))
286 goto freeit;
287
288 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
289 m = m_gethdr(M_NOWAIT, MT_DATA);
290 else
291 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
292 if (m == NULL)
293 goto freeit;
294 #ifdef MAC
295 mac_netinet_icmp_reply(n, m);
296 #endif
297 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
298 m_align(m, ICMP_MINLEN + icmplen);
299 m->m_len = ICMP_MINLEN + icmplen;
300
301 /* XXX MRT make the outgoing packet use the same FIB
302 * that was associated with the incoming packet
303 */
304 M_SETFIB(m, M_GETFIB(n));
305 icp = mtod(m, struct icmp *);
306 ICMPSTAT_INC(icps_outhist[type]);
307 icp->icmp_type = type;
308 if (type == ICMP_REDIRECT)
309 icp->icmp_gwaddr.s_addr = dest;
310 else {
311 icp->icmp_void = 0;
312 /*
313 * The following assignments assume an overlay with the
314 * just zeroed icmp_void field.
315 */
316 if (type == ICMP_PARAMPROB) {
317 icp->icmp_pptr = code;
318 code = 0;
319 } else if (type == ICMP_UNREACH &&
320 code == ICMP_UNREACH_NEEDFRAG && mtu) {
321 icp->icmp_nextmtu = htons(mtu);
322 }
323 }
324 icp->icmp_code = code;
325
326 /*
327 * Copy the quotation into ICMP message and
328 * convert quoted IP header back to network representation.
329 */
330 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
331 nip = &icp->icmp_ip;
332
333 /*
334 * Set up ICMP message mbuf and copy old IP header (without options
335 * in front of ICMP message.
336 * If the original mbuf was meant to bypass the firewall, the error
337 * reply should bypass as well.
338 */
339 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
340 m->m_data -= sizeof(struct ip);
341 m->m_len += sizeof(struct ip);
342 m->m_pkthdr.len = m->m_len;
343 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
344 nip = mtod(m, struct ip *);
345 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
346 nip->ip_len = htons(m->m_len);
347 nip->ip_v = IPVERSION;
348 nip->ip_hl = 5;
349 nip->ip_p = IPPROTO_ICMP;
350 nip->ip_tos = 0;
351 nip->ip_off = 0;
352 icmp_reflect(m);
353
354 freeit:
355 m_freem(n);
356 }
357
358 /*
359 * Process a received ICMP message.
360 */
361 int
362 icmp_input(struct mbuf **mp, int *offp, int proto)
363 {
364 struct icmp *icp;
365 struct in_ifaddr *ia;
366 struct mbuf *m = *mp;
367 struct ip *ip = mtod(m, struct ip *);
368 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
369 int hlen = *offp;
370 int icmplen = ntohs(ip->ip_len) - *offp;
371 int i, code;
372 void (*ctlfunc)(int, struct sockaddr *, void *);
373 int fibnum;
374
375 *mp = NULL;
376
377 /*
378 * Locate icmp structure in mbuf, and check
379 * that not corrupted and of at least minimum length.
380 */
381 #ifdef ICMPPRINTFS
382 if (icmpprintfs) {
383 char srcbuf[INET_ADDRSTRLEN];
384 char dstbuf[INET_ADDRSTRLEN];
385
386 printf("icmp_input from %s to %s, len %d\n",
387 inet_ntoa_r(ip->ip_src, srcbuf),
388 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen);
389 }
390 #endif
391 if (icmplen < ICMP_MINLEN) {
392 ICMPSTAT_INC(icps_tooshort);
393 goto freeit;
394 }
395 i = hlen + min(icmplen, ICMP_ADVLENMIN);
396 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
397 ICMPSTAT_INC(icps_tooshort);
398 return (IPPROTO_DONE);
399 }
400 ip = mtod(m, struct ip *);
401 m->m_len -= hlen;
402 m->m_data += hlen;
403 icp = mtod(m, struct icmp *);
404 if (in_cksum(m, icmplen)) {
405 ICMPSTAT_INC(icps_checksum);
406 goto freeit;
407 }
408 m->m_len += hlen;
409 m->m_data -= hlen;
410
411 #ifdef ICMPPRINTFS
412 if (icmpprintfs)
413 printf("icmp_input, type %d code %d\n", icp->icmp_type,
414 icp->icmp_code);
415 #endif
416
417 /*
418 * Message type specific processing.
419 */
420 if (icp->icmp_type > ICMP_MAXTYPE)
421 goto raw;
422
423 /* Initialize */
424 bzero(&icmpsrc, sizeof(icmpsrc));
425 icmpsrc.sin_len = sizeof(struct sockaddr_in);
426 icmpsrc.sin_family = AF_INET;
427 bzero(&icmpdst, sizeof(icmpdst));
428 icmpdst.sin_len = sizeof(struct sockaddr_in);
429 icmpdst.sin_family = AF_INET;
430 bzero(&icmpgw, sizeof(icmpgw));
431 icmpgw.sin_len = sizeof(struct sockaddr_in);
432 icmpgw.sin_family = AF_INET;
433
434 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
435 code = icp->icmp_code;
436 switch (icp->icmp_type) {
437
438 case ICMP_UNREACH:
439 switch (code) {
440 case ICMP_UNREACH_NET:
441 case ICMP_UNREACH_HOST:
442 case ICMP_UNREACH_SRCFAIL:
443 case ICMP_UNREACH_NET_UNKNOWN:
444 case ICMP_UNREACH_HOST_UNKNOWN:
445 case ICMP_UNREACH_ISOLATED:
446 case ICMP_UNREACH_TOSNET:
447 case ICMP_UNREACH_TOSHOST:
448 case ICMP_UNREACH_HOST_PRECEDENCE:
449 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
450 code = PRC_UNREACH_NET;
451 break;
452
453 case ICMP_UNREACH_NEEDFRAG:
454 code = PRC_MSGSIZE;
455 break;
456
457 /*
458 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
459 * Treat subcodes 2,3 as immediate RST
460 */
461 case ICMP_UNREACH_PROTOCOL:
462 code = PRC_UNREACH_PROTOCOL;
463 break;
464 case ICMP_UNREACH_PORT:
465 code = PRC_UNREACH_PORT;
466 break;
467
468 case ICMP_UNREACH_NET_PROHIB:
469 case ICMP_UNREACH_HOST_PROHIB:
470 case ICMP_UNREACH_FILTER_PROHIB:
471 code = PRC_UNREACH_ADMIN_PROHIB;
472 break;
473
474 default:
475 goto badcode;
476 }
477 goto deliver;
478
479 case ICMP_TIMXCEED:
480 if (code > 1)
481 goto badcode;
482 code += PRC_TIMXCEED_INTRANS;
483 goto deliver;
484
485 case ICMP_PARAMPROB:
486 if (code > 1)
487 goto badcode;
488 code = PRC_PARAMPROB;
489 deliver:
490 /*
491 * Problem with datagram; advise higher level routines.
492 */
493 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
494 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
495 ICMPSTAT_INC(icps_badlen);
496 goto freeit;
497 }
498 /* Discard ICMP's in response to multicast packets */
499 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
500 goto badcode;
501 #ifdef ICMPPRINTFS
502 if (icmpprintfs)
503 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
504 #endif
505 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
506 /*
507 * XXX if the packet contains [IPv4 AH TCP], we can't make a
508 * notification to TCP layer.
509 */
510 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp));
511 ip_stripoptions(m);
512 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
513 /* This should actually not happen */
514 ICMPSTAT_INC(icps_tooshort);
515 return (IPPROTO_DONE);
516 }
517 ip = mtod(m, struct ip *);
518 icp = (struct icmp *)(ip + 1);
519 /*
520 * The upper layer handler can rely on:
521 * - The outer IP header has no options.
522 * - The outer IP header, the ICMP header, the inner IP header,
523 * and the first n bytes of the inner payload are contiguous.
524 * n is at least 8, but might be larger based on
525 * ICMP_ADVLENPREF. See its definition in ip_icmp.h.
526 */
527 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
528 if (ctlfunc)
529 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
530 (void *)&icp->icmp_ip);
531 break;
532
533 badcode:
534 ICMPSTAT_INC(icps_badcode);
535 break;
536
537 case ICMP_ECHO:
538 if (!V_icmpbmcastecho
539 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
540 ICMPSTAT_INC(icps_bmcastecho);
541 break;
542 }
543 icp->icmp_type = ICMP_ECHOREPLY;
544 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
545 goto freeit;
546 else
547 goto reflect;
548
549 case ICMP_TSTAMP:
550 if (V_icmptstamprepl == 0)
551 break;
552 if (!V_icmpbmcastecho
553 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
554 ICMPSTAT_INC(icps_bmcasttstamp);
555 break;
556 }
557 if (icmplen < ICMP_TSLEN) {
558 ICMPSTAT_INC(icps_badlen);
559 break;
560 }
561 icp->icmp_type = ICMP_TSTAMPREPLY;
562 icp->icmp_rtime = iptime();
563 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
564 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
565 goto freeit;
566 else
567 goto reflect;
568
569 case ICMP_MASKREQ:
570 if (V_icmpmaskrepl == 0)
571 break;
572 /*
573 * We are not able to respond with all ones broadcast
574 * unless we receive it over a point-to-point interface.
575 */
576 if (icmplen < ICMP_MASKLEN)
577 break;
578 switch (ip->ip_dst.s_addr) {
579
580 case INADDR_BROADCAST:
581 case INADDR_ANY:
582 icmpdst.sin_addr = ip->ip_src;
583 break;
584
585 default:
586 icmpdst.sin_addr = ip->ip_dst;
587 }
588 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
589 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
590 if (ia == NULL)
591 break;
592 if (ia->ia_ifp == NULL) {
593 ifa_free(&ia->ia_ifa);
594 break;
595 }
596 icp->icmp_type = ICMP_MASKREPLY;
597 if (V_icmpmaskfake == 0)
598 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
599 else
600 icp->icmp_mask = V_icmpmaskfake;
601 if (ip->ip_src.s_addr == 0) {
602 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
603 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
604 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
605 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
606 }
607 ifa_free(&ia->ia_ifa);
608 reflect:
609 ICMPSTAT_INC(icps_reflect);
610 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
611 icmp_reflect(m);
612 return (IPPROTO_DONE);
613
614 case ICMP_REDIRECT:
615 if (V_log_redirect) {
616 u_long src, dst, gw;
617
618 src = ntohl(ip->ip_src.s_addr);
619 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
620 gw = ntohl(icp->icmp_gwaddr.s_addr);
621 printf("icmp redirect from %d.%d.%d.%d: "
622 "%d.%d.%d.%d => %d.%d.%d.%d\n",
623 (int)(src >> 24), (int)((src >> 16) & 0xff),
624 (int)((src >> 8) & 0xff), (int)(src & 0xff),
625 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
626 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
627 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
628 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
629 }
630 /*
631 * RFC1812 says we must ignore ICMP redirects if we
632 * are acting as router.
633 */
634 if (V_drop_redirect || V_ipforwarding)
635 break;
636 if (code > 3)
637 goto badcode;
638 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
639 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
640 ICMPSTAT_INC(icps_badlen);
641 break;
642 }
643 /*
644 * Short circuit routing redirects to force
645 * immediate change in the kernel's routing
646 * tables. The message is also handed to anyone
647 * listening on a raw socket (e.g. the routing
648 * daemon for use in updating its tables).
649 */
650 icmpgw.sin_addr = ip->ip_src;
651 icmpdst.sin_addr = icp->icmp_gwaddr;
652 #ifdef ICMPPRINTFS
653 if (icmpprintfs) {
654 char dstbuf[INET_ADDRSTRLEN];
655 char gwbuf[INET_ADDRSTRLEN];
656
657 printf("redirect dst %s to %s\n",
658 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf),
659 inet_ntoa_r(icp->icmp_gwaddr, gwbuf));
660 }
661 #endif
662 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
663 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
664 in_rtredirect((struct sockaddr *)&icmpsrc,
665 (struct sockaddr *)&icmpdst,
666 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
667 (struct sockaddr *)&icmpgw, fibnum);
668 }
669 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
670 break;
671
672 /*
673 * No kernel processing for the following;
674 * just fall through to send to raw listener.
675 */
676 case ICMP_ECHOREPLY:
677 case ICMP_ROUTERADVERT:
678 case ICMP_ROUTERSOLICIT:
679 case ICMP_TSTAMPREPLY:
680 case ICMP_IREQREPLY:
681 case ICMP_MASKREPLY:
682 case ICMP_SOURCEQUENCH:
683 default:
684 break;
685 }
686
687 raw:
688 *mp = m;
689 rip_input(mp, offp, proto);
690 return (IPPROTO_DONE);
691
692 freeit:
693 m_freem(m);
694 return (IPPROTO_DONE);
695 }
696
697 /*
698 * Reflect the ip packet back to the source
699 */
700 static void
701 icmp_reflect(struct mbuf *m)
702 {
703 struct rm_priotracker in_ifa_tracker;
704 struct ip *ip = mtod(m, struct ip *);
705 struct ifaddr *ifa;
706 struct ifnet *ifp;
707 struct in_ifaddr *ia;
708 struct in_addr t;
709 struct nhop4_extended nh_ext;
710 struct mbuf *opts = NULL;
711 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
712
713 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
714 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
715 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
716 m_freem(m); /* Bad return address */
717 ICMPSTAT_INC(icps_badaddr);
718 goto done; /* Ip_output() will check for broadcast */
719 }
720
721 t = ip->ip_dst;
722 ip->ip_dst = ip->ip_src;
723
724 /*
725 * Source selection for ICMP replies:
726 *
727 * If the incoming packet was addressed directly to one of our
728 * own addresses, use dst as the src for the reply.
729 */
730 IN_IFADDR_RLOCK(&in_ifa_tracker);
731 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
732 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
733 t = IA_SIN(ia)->sin_addr;
734 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
735 goto match;
736 }
737 }
738 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
739
740 /*
741 * If the incoming packet was addressed to one of our broadcast
742 * addresses, use the first non-broadcast address which corresponds
743 * to the incoming interface.
744 */
745 ifp = m->m_pkthdr.rcvif;
746 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
747 IF_ADDR_RLOCK(ifp);
748 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
749 if (ifa->ifa_addr->sa_family != AF_INET)
750 continue;
751 ia = ifatoia(ifa);
752 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
753 t.s_addr) {
754 t = IA_SIN(ia)->sin_addr;
755 IF_ADDR_RUNLOCK(ifp);
756 goto match;
757 }
758 }
759 IF_ADDR_RUNLOCK(ifp);
760 }
761 /*
762 * If the packet was transiting through us, use the address of
763 * the interface the packet came through in. If that interface
764 * doesn't have a suitable IP address, the normal selection
765 * criteria apply.
766 */
767 if (V_icmp_rfi && ifp != NULL) {
768 IF_ADDR_RLOCK(ifp);
769 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
770 if (ifa->ifa_addr->sa_family != AF_INET)
771 continue;
772 ia = ifatoia(ifa);
773 t = IA_SIN(ia)->sin_addr;
774 IF_ADDR_RUNLOCK(ifp);
775 goto match;
776 }
777 IF_ADDR_RUNLOCK(ifp);
778 }
779 /*
780 * If the incoming packet was not addressed directly to us, use
781 * designated interface for icmp replies specified by sysctl
782 * net.inet.icmp.reply_src (default not set). Otherwise continue
783 * with normal source selection.
784 */
785 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
786 IF_ADDR_RLOCK(ifp);
787 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
788 if (ifa->ifa_addr->sa_family != AF_INET)
789 continue;
790 ia = ifatoia(ifa);
791 t = IA_SIN(ia)->sin_addr;
792 IF_ADDR_RUNLOCK(ifp);
793 goto match;
794 }
795 IF_ADDR_RUNLOCK(ifp);
796 }
797 /*
798 * If the packet was transiting through us, use the address of
799 * the interface that is the closest to the packet source.
800 * When we don't have a route back to the packet source, stop here
801 * and drop the packet.
802 */
803 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) {
804 m_freem(m);
805 ICMPSTAT_INC(icps_noroute);
806 goto done;
807 }
808 t = nh_ext.nh_src;
809 match:
810 #ifdef MAC
811 mac_netinet_icmp_replyinplace(m);
812 #endif
813 ip->ip_src = t;
814 ip->ip_ttl = V_ip_defttl;
815
816 if (optlen > 0) {
817 register u_char *cp;
818 int opt, cnt;
819 u_int len;
820
821 /*
822 * Retrieve any source routing from the incoming packet;
823 * add on any record-route or timestamp options.
824 */
825 cp = (u_char *) (ip + 1);
826 if ((opts = ip_srcroute(m)) == NULL &&
827 (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
828 opts->m_len = sizeof(struct in_addr);
829 mtod(opts, struct in_addr *)->s_addr = 0;
830 }
831 if (opts) {
832 #ifdef ICMPPRINTFS
833 if (icmpprintfs)
834 printf("icmp_reflect optlen %d rt %d => ",
835 optlen, opts->m_len);
836 #endif
837 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
838 opt = cp[IPOPT_OPTVAL];
839 if (opt == IPOPT_EOL)
840 break;
841 if (opt == IPOPT_NOP)
842 len = 1;
843 else {
844 if (cnt < IPOPT_OLEN + sizeof(*cp))
845 break;
846 len = cp[IPOPT_OLEN];
847 if (len < IPOPT_OLEN + sizeof(*cp) ||
848 len > cnt)
849 break;
850 }
851 /*
852 * Should check for overflow, but it "can't happen"
853 */
854 if (opt == IPOPT_RR || opt == IPOPT_TS ||
855 opt == IPOPT_SECURITY) {
856 bcopy((caddr_t)cp,
857 mtod(opts, caddr_t) + opts->m_len, len);
858 opts->m_len += len;
859 }
860 }
861 /* Terminate & pad, if necessary */
862 cnt = opts->m_len % 4;
863 if (cnt) {
864 for (; cnt < 4; cnt++) {
865 *(mtod(opts, caddr_t) + opts->m_len) =
866 IPOPT_EOL;
867 opts->m_len++;
868 }
869 }
870 #ifdef ICMPPRINTFS
871 if (icmpprintfs)
872 printf("%d\n", opts->m_len);
873 #endif
874 }
875 ip_stripoptions(m);
876 }
877 m_tag_delete_nonpersistent(m);
878 m->m_flags &= ~(M_BCAST|M_MCAST);
879 icmp_send(m, opts);
880 done:
881 if (opts)
882 (void)m_free(opts);
883 }
884
885 /*
886 * Send an icmp packet back to the ip level,
887 * after supplying a checksum.
888 */
889 static void
890 icmp_send(struct mbuf *m, struct mbuf *opts)
891 {
892 register struct ip *ip = mtod(m, struct ip *);
893 register int hlen;
894 register struct icmp *icp;
895
896 hlen = ip->ip_hl << 2;
897 m->m_data += hlen;
898 m->m_len -= hlen;
899 icp = mtod(m, struct icmp *);
900 icp->icmp_cksum = 0;
901 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
902 m->m_data -= hlen;
903 m->m_len += hlen;
904 m->m_pkthdr.rcvif = (struct ifnet *)0;
905 #ifdef ICMPPRINTFS
906 if (icmpprintfs) {
907 char dstbuf[INET_ADDRSTRLEN];
908 char srcbuf[INET_ADDRSTRLEN];
909
910 printf("icmp_send dst %s src %s\n",
911 inet_ntoa_r(ip->ip_dst, dstbuf),
912 inet_ntoa_r(ip->ip_src, srcbuf));
913 }
914 #endif
915 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
916 }
917
918 /*
919 * Return milliseconds since 00:00 UTC in network format.
920 */
921 uint32_t
922 iptime(void)
923 {
924 struct timeval atv;
925 u_long t;
926
927 getmicrotime(&atv);
928 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
929 return (htonl(t));
930 }
931
932 /*
933 * Return the next larger or smaller MTU plateau (table from RFC 1191)
934 * given current value MTU. If DIR is less than zero, a larger plateau
935 * is returned; otherwise, a smaller value is returned.
936 */
937 int
938 ip_next_mtu(int mtu, int dir)
939 {
940 static int mtutab[] = {
941 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
942 296, 68, 0
943 };
944 int i, size;
945
946 size = (sizeof mtutab) / (sizeof mtutab[0]);
947 if (dir >= 0) {
948 for (i = 0; i < size; i++)
949 if (mtu > mtutab[i])
950 return mtutab[i];
951 } else {
952 for (i = size - 1; i >= 0; i--)
953 if (mtu < mtutab[i])
954 return mtutab[i];
955 if (mtu == mtutab[0])
956 return mtutab[0];
957 }
958 return 0;
959 }
960 #endif /* INET */
961
962
963 /*
964 * badport_bandlim() - check for ICMP bandwidth limit
965 *
966 * Return 0 if it is ok to send an ICMP error response, -1 if we have
967 * hit our bandwidth limit and it is not ok.
968 *
969 * If icmplim is <= 0, the feature is disabled and 0 is returned.
970 *
971 * For now we separate the TCP and UDP subsystems w/ different 'which'
972 * values. We may eventually remove this separation (and simplify the
973 * code further).
974 *
975 * Note that the printing of the error message is delayed so we can
976 * properly print the icmp error rate that the system was trying to do
977 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
978 * the 'final' error, but it doesn't make sense to solve the printing
979 * delay with more complex code.
980 */
981
982 int
983 badport_bandlim(int which)
984 {
985
986 #define N(a) (sizeof (a) / sizeof (a[0]))
987 static struct rate {
988 const char *type;
989 struct timeval lasttime;
990 int curpps;
991 } rates[BANDLIM_MAX+1] = {
992 { "icmp unreach response" },
993 { "icmp ping response" },
994 { "icmp tstamp response" },
995 { "closed port RST response" },
996 { "open port RST response" },
997 { "icmp6 unreach response" },
998 { "sctp ootb response" }
999 };
1000
1001 /*
1002 * Return ok status if feature disabled or argument out of range.
1003 */
1004 if (V_icmplim > 0 && (u_int) which < N(rates)) {
1005 struct rate *r = &rates[which];
1006 int opps = r->curpps;
1007
1008 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
1009 return -1; /* discard packet */
1010 /*
1011 * If we've dropped below the threshold after having
1012 * rate-limited traffic print the message. This preserves
1013 * the previous behaviour at the expense of added complexity.
1014 */
1015 if (V_icmplim_output && opps > V_icmplim)
1016 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
1017 r->type, opps, V_icmplim);
1018 }
1019 return 0; /* okay to send packet */
1020 #undef N
1021 }
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