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/11.0/sys/netinet/ip_icmp.c 300699 2016-05-25 22:16:11Z tuexen $");
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 buf[4 * sizeof "123"];
384 strcpy(buf, inet_ntoa(ip->ip_src));
385 printf("icmp_input from %s to %s, len %d\n",
386 buf, inet_ntoa(ip->ip_dst), icmplen);
387 }
388 #endif
389 if (icmplen < ICMP_MINLEN) {
390 ICMPSTAT_INC(icps_tooshort);
391 goto freeit;
392 }
393 i = hlen + min(icmplen, ICMP_ADVLENMIN);
394 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
395 ICMPSTAT_INC(icps_tooshort);
396 return (IPPROTO_DONE);
397 }
398 ip = mtod(m, struct ip *);
399 m->m_len -= hlen;
400 m->m_data += hlen;
401 icp = mtod(m, struct icmp *);
402 if (in_cksum(m, icmplen)) {
403 ICMPSTAT_INC(icps_checksum);
404 goto freeit;
405 }
406 m->m_len += hlen;
407 m->m_data -= hlen;
408
409 #ifdef ICMPPRINTFS
410 if (icmpprintfs)
411 printf("icmp_input, type %d code %d\n", icp->icmp_type,
412 icp->icmp_code);
413 #endif
414
415 /*
416 * Message type specific processing.
417 */
418 if (icp->icmp_type > ICMP_MAXTYPE)
419 goto raw;
420
421 /* Initialize */
422 bzero(&icmpsrc, sizeof(icmpsrc));
423 icmpsrc.sin_len = sizeof(struct sockaddr_in);
424 icmpsrc.sin_family = AF_INET;
425 bzero(&icmpdst, sizeof(icmpdst));
426 icmpdst.sin_len = sizeof(struct sockaddr_in);
427 icmpdst.sin_family = AF_INET;
428 bzero(&icmpgw, sizeof(icmpgw));
429 icmpgw.sin_len = sizeof(struct sockaddr_in);
430 icmpgw.sin_family = AF_INET;
431
432 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
433 code = icp->icmp_code;
434 switch (icp->icmp_type) {
435
436 case ICMP_UNREACH:
437 switch (code) {
438 case ICMP_UNREACH_NET:
439 case ICMP_UNREACH_HOST:
440 case ICMP_UNREACH_SRCFAIL:
441 case ICMP_UNREACH_NET_UNKNOWN:
442 case ICMP_UNREACH_HOST_UNKNOWN:
443 case ICMP_UNREACH_ISOLATED:
444 case ICMP_UNREACH_TOSNET:
445 case ICMP_UNREACH_TOSHOST:
446 case ICMP_UNREACH_HOST_PRECEDENCE:
447 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
448 code = PRC_UNREACH_NET;
449 break;
450
451 case ICMP_UNREACH_NEEDFRAG:
452 code = PRC_MSGSIZE;
453 break;
454
455 /*
456 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
457 * Treat subcodes 2,3 as immediate RST
458 */
459 case ICMP_UNREACH_PROTOCOL:
460 case ICMP_UNREACH_PORT:
461 code = PRC_UNREACH_PORT;
462 break;
463
464 case ICMP_UNREACH_NET_PROHIB:
465 case ICMP_UNREACH_HOST_PROHIB:
466 case ICMP_UNREACH_FILTER_PROHIB:
467 code = PRC_UNREACH_ADMIN_PROHIB;
468 break;
469
470 default:
471 goto badcode;
472 }
473 goto deliver;
474
475 case ICMP_TIMXCEED:
476 if (code > 1)
477 goto badcode;
478 code += PRC_TIMXCEED_INTRANS;
479 goto deliver;
480
481 case ICMP_PARAMPROB:
482 if (code > 1)
483 goto badcode;
484 code = PRC_PARAMPROB;
485 deliver:
486 /*
487 * Problem with datagram; advise higher level routines.
488 */
489 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
490 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
491 ICMPSTAT_INC(icps_badlen);
492 goto freeit;
493 }
494 /* Discard ICMP's in response to multicast packets */
495 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
496 goto badcode;
497 #ifdef ICMPPRINTFS
498 if (icmpprintfs)
499 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
500 #endif
501 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
502 /*
503 * XXX if the packet contains [IPv4 AH TCP], we can't make a
504 * notification to TCP layer.
505 */
506 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp));
507 ip_stripoptions(m);
508 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
509 /* This should actually not happen */
510 ICMPSTAT_INC(icps_tooshort);
511 return (IPPROTO_DONE);
512 }
513 ip = mtod(m, struct ip *);
514 icp = (struct icmp *)(ip + 1);
515 /*
516 * The upper layer handler can rely on:
517 * - The outer IP header has no options.
518 * - The outer IP header, the ICMP header, the inner IP header,
519 * and the first n bytes of the inner payload are contiguous.
520 * n is at least 8, but might be larger based on
521 * ICMP_ADVLENPREF. See its definition in ip_icmp.h.
522 */
523 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
524 if (ctlfunc)
525 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
526 (void *)&icp->icmp_ip);
527 break;
528
529 badcode:
530 ICMPSTAT_INC(icps_badcode);
531 break;
532
533 case ICMP_ECHO:
534 if (!V_icmpbmcastecho
535 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
536 ICMPSTAT_INC(icps_bmcastecho);
537 break;
538 }
539 icp->icmp_type = ICMP_ECHOREPLY;
540 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
541 goto freeit;
542 else
543 goto reflect;
544
545 case ICMP_TSTAMP:
546 if (V_icmptstamprepl == 0)
547 break;
548 if (!V_icmpbmcastecho
549 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
550 ICMPSTAT_INC(icps_bmcasttstamp);
551 break;
552 }
553 if (icmplen < ICMP_TSLEN) {
554 ICMPSTAT_INC(icps_badlen);
555 break;
556 }
557 icp->icmp_type = ICMP_TSTAMPREPLY;
558 icp->icmp_rtime = iptime();
559 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
560 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
561 goto freeit;
562 else
563 goto reflect;
564
565 case ICMP_MASKREQ:
566 if (V_icmpmaskrepl == 0)
567 break;
568 /*
569 * We are not able to respond with all ones broadcast
570 * unless we receive it over a point-to-point interface.
571 */
572 if (icmplen < ICMP_MASKLEN)
573 break;
574 switch (ip->ip_dst.s_addr) {
575
576 case INADDR_BROADCAST:
577 case INADDR_ANY:
578 icmpdst.sin_addr = ip->ip_src;
579 break;
580
581 default:
582 icmpdst.sin_addr = ip->ip_dst;
583 }
584 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
585 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
586 if (ia == NULL)
587 break;
588 if (ia->ia_ifp == NULL) {
589 ifa_free(&ia->ia_ifa);
590 break;
591 }
592 icp->icmp_type = ICMP_MASKREPLY;
593 if (V_icmpmaskfake == 0)
594 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
595 else
596 icp->icmp_mask = V_icmpmaskfake;
597 if (ip->ip_src.s_addr == 0) {
598 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
599 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
600 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
601 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
602 }
603 ifa_free(&ia->ia_ifa);
604 reflect:
605 ICMPSTAT_INC(icps_reflect);
606 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
607 icmp_reflect(m);
608 return (IPPROTO_DONE);
609
610 case ICMP_REDIRECT:
611 if (V_log_redirect) {
612 u_long src, dst, gw;
613
614 src = ntohl(ip->ip_src.s_addr);
615 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
616 gw = ntohl(icp->icmp_gwaddr.s_addr);
617 printf("icmp redirect from %d.%d.%d.%d: "
618 "%d.%d.%d.%d => %d.%d.%d.%d\n",
619 (int)(src >> 24), (int)((src >> 16) & 0xff),
620 (int)((src >> 8) & 0xff), (int)(src & 0xff),
621 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
622 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
623 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
624 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
625 }
626 /*
627 * RFC1812 says we must ignore ICMP redirects if we
628 * are acting as router.
629 */
630 if (V_drop_redirect || V_ipforwarding)
631 break;
632 if (code > 3)
633 goto badcode;
634 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
635 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
636 ICMPSTAT_INC(icps_badlen);
637 break;
638 }
639 /*
640 * Short circuit routing redirects to force
641 * immediate change in the kernel's routing
642 * tables. The message is also handed to anyone
643 * listening on a raw socket (e.g. the routing
644 * daemon for use in updating its tables).
645 */
646 icmpgw.sin_addr = ip->ip_src;
647 icmpdst.sin_addr = icp->icmp_gwaddr;
648 #ifdef ICMPPRINTFS
649 if (icmpprintfs) {
650 char buf[4 * sizeof "123"];
651 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
652
653 printf("redirect dst %s to %s\n",
654 buf, inet_ntoa(icp->icmp_gwaddr));
655 }
656 #endif
657 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
658 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
659 in_rtredirect((struct sockaddr *)&icmpsrc,
660 (struct sockaddr *)&icmpdst,
661 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
662 (struct sockaddr *)&icmpgw, fibnum);
663 }
664 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
665 break;
666
667 /*
668 * No kernel processing for the following;
669 * just fall through to send to raw listener.
670 */
671 case ICMP_ECHOREPLY:
672 case ICMP_ROUTERADVERT:
673 case ICMP_ROUTERSOLICIT:
674 case ICMP_TSTAMPREPLY:
675 case ICMP_IREQREPLY:
676 case ICMP_MASKREPLY:
677 case ICMP_SOURCEQUENCH:
678 default:
679 break;
680 }
681
682 raw:
683 *mp = m;
684 rip_input(mp, offp, proto);
685 return (IPPROTO_DONE);
686
687 freeit:
688 m_freem(m);
689 return (IPPROTO_DONE);
690 }
691
692 /*
693 * Reflect the ip packet back to the source
694 */
695 static void
696 icmp_reflect(struct mbuf *m)
697 {
698 struct rm_priotracker in_ifa_tracker;
699 struct ip *ip = mtod(m, struct ip *);
700 struct ifaddr *ifa;
701 struct ifnet *ifp;
702 struct in_ifaddr *ia;
703 struct in_addr t;
704 struct nhop4_extended nh_ext;
705 struct mbuf *opts = NULL;
706 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
707
708 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
709 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
710 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
711 m_freem(m); /* Bad return address */
712 ICMPSTAT_INC(icps_badaddr);
713 goto done; /* Ip_output() will check for broadcast */
714 }
715
716 t = ip->ip_dst;
717 ip->ip_dst = ip->ip_src;
718
719 /*
720 * Source selection for ICMP replies:
721 *
722 * If the incoming packet was addressed directly to one of our
723 * own addresses, use dst as the src for the reply.
724 */
725 IN_IFADDR_RLOCK(&in_ifa_tracker);
726 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
727 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
728 t = IA_SIN(ia)->sin_addr;
729 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
730 goto match;
731 }
732 }
733 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
734
735 /*
736 * If the incoming packet was addressed to one of our broadcast
737 * addresses, use the first non-broadcast address which corresponds
738 * to the incoming interface.
739 */
740 ifp = m->m_pkthdr.rcvif;
741 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
742 IF_ADDR_RLOCK(ifp);
743 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
744 if (ifa->ifa_addr->sa_family != AF_INET)
745 continue;
746 ia = ifatoia(ifa);
747 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
748 t.s_addr) {
749 t = IA_SIN(ia)->sin_addr;
750 IF_ADDR_RUNLOCK(ifp);
751 goto match;
752 }
753 }
754 IF_ADDR_RUNLOCK(ifp);
755 }
756 /*
757 * If the packet was transiting through us, use the address of
758 * the interface the packet came through in. If that interface
759 * doesn't have a suitable IP address, the normal selection
760 * criteria apply.
761 */
762 if (V_icmp_rfi && ifp != NULL) {
763 IF_ADDR_RLOCK(ifp);
764 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
765 if (ifa->ifa_addr->sa_family != AF_INET)
766 continue;
767 ia = ifatoia(ifa);
768 t = IA_SIN(ia)->sin_addr;
769 IF_ADDR_RUNLOCK(ifp);
770 goto match;
771 }
772 IF_ADDR_RUNLOCK(ifp);
773 }
774 /*
775 * If the incoming packet was not addressed directly to us, use
776 * designated interface for icmp replies specified by sysctl
777 * net.inet.icmp.reply_src (default not set). Otherwise continue
778 * with normal source selection.
779 */
780 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
781 IF_ADDR_RLOCK(ifp);
782 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
783 if (ifa->ifa_addr->sa_family != AF_INET)
784 continue;
785 ia = ifatoia(ifa);
786 t = IA_SIN(ia)->sin_addr;
787 IF_ADDR_RUNLOCK(ifp);
788 goto match;
789 }
790 IF_ADDR_RUNLOCK(ifp);
791 }
792 /*
793 * If the packet was transiting through us, use the address of
794 * the interface that is the closest to the packet source.
795 * When we don't have a route back to the packet source, stop here
796 * and drop the packet.
797 */
798 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) {
799 m_freem(m);
800 ICMPSTAT_INC(icps_noroute);
801 goto done;
802 }
803 t = nh_ext.nh_src;
804 match:
805 #ifdef MAC
806 mac_netinet_icmp_replyinplace(m);
807 #endif
808 ip->ip_src = t;
809 ip->ip_ttl = V_ip_defttl;
810
811 if (optlen > 0) {
812 register u_char *cp;
813 int opt, cnt;
814 u_int len;
815
816 /*
817 * Retrieve any source routing from the incoming packet;
818 * add on any record-route or timestamp options.
819 */
820 cp = (u_char *) (ip + 1);
821 if ((opts = ip_srcroute(m)) == NULL &&
822 (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
823 opts->m_len = sizeof(struct in_addr);
824 mtod(opts, struct in_addr *)->s_addr = 0;
825 }
826 if (opts) {
827 #ifdef ICMPPRINTFS
828 if (icmpprintfs)
829 printf("icmp_reflect optlen %d rt %d => ",
830 optlen, opts->m_len);
831 #endif
832 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
833 opt = cp[IPOPT_OPTVAL];
834 if (opt == IPOPT_EOL)
835 break;
836 if (opt == IPOPT_NOP)
837 len = 1;
838 else {
839 if (cnt < IPOPT_OLEN + sizeof(*cp))
840 break;
841 len = cp[IPOPT_OLEN];
842 if (len < IPOPT_OLEN + sizeof(*cp) ||
843 len > cnt)
844 break;
845 }
846 /*
847 * Should check for overflow, but it "can't happen"
848 */
849 if (opt == IPOPT_RR || opt == IPOPT_TS ||
850 opt == IPOPT_SECURITY) {
851 bcopy((caddr_t)cp,
852 mtod(opts, caddr_t) + opts->m_len, len);
853 opts->m_len += len;
854 }
855 }
856 /* Terminate & pad, if necessary */
857 cnt = opts->m_len % 4;
858 if (cnt) {
859 for (; cnt < 4; cnt++) {
860 *(mtod(opts, caddr_t) + opts->m_len) =
861 IPOPT_EOL;
862 opts->m_len++;
863 }
864 }
865 #ifdef ICMPPRINTFS
866 if (icmpprintfs)
867 printf("%d\n", opts->m_len);
868 #endif
869 }
870 ip_stripoptions(m);
871 }
872 m_tag_delete_nonpersistent(m);
873 m->m_flags &= ~(M_BCAST|M_MCAST);
874 icmp_send(m, opts);
875 done:
876 if (opts)
877 (void)m_free(opts);
878 }
879
880 /*
881 * Send an icmp packet back to the ip level,
882 * after supplying a checksum.
883 */
884 static void
885 icmp_send(struct mbuf *m, struct mbuf *opts)
886 {
887 register struct ip *ip = mtod(m, struct ip *);
888 register int hlen;
889 register struct icmp *icp;
890
891 hlen = ip->ip_hl << 2;
892 m->m_data += hlen;
893 m->m_len -= hlen;
894 icp = mtod(m, struct icmp *);
895 icp->icmp_cksum = 0;
896 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
897 m->m_data -= hlen;
898 m->m_len += hlen;
899 m->m_pkthdr.rcvif = (struct ifnet *)0;
900 #ifdef ICMPPRINTFS
901 if (icmpprintfs) {
902 char buf[4 * sizeof "123"];
903 strcpy(buf, inet_ntoa(ip->ip_dst));
904 printf("icmp_send dst %s src %s\n",
905 buf, inet_ntoa(ip->ip_src));
906 }
907 #endif
908 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
909 }
910
911 /*
912 * Return milliseconds since 00:00 UTC in network format.
913 */
914 uint32_t
915 iptime(void)
916 {
917 struct timeval atv;
918 u_long t;
919
920 getmicrotime(&atv);
921 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
922 return (htonl(t));
923 }
924
925 /*
926 * Return the next larger or smaller MTU plateau (table from RFC 1191)
927 * given current value MTU. If DIR is less than zero, a larger plateau
928 * is returned; otherwise, a smaller value is returned.
929 */
930 int
931 ip_next_mtu(int mtu, int dir)
932 {
933 static int mtutab[] = {
934 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
935 296, 68, 0
936 };
937 int i, size;
938
939 size = (sizeof mtutab) / (sizeof mtutab[0]);
940 if (dir >= 0) {
941 for (i = 0; i < size; i++)
942 if (mtu > mtutab[i])
943 return mtutab[i];
944 } else {
945 for (i = size - 1; i >= 0; i--)
946 if (mtu < mtutab[i])
947 return mtutab[i];
948 if (mtu == mtutab[0])
949 return mtutab[0];
950 }
951 return 0;
952 }
953 #endif /* INET */
954
955
956 /*
957 * badport_bandlim() - check for ICMP bandwidth limit
958 *
959 * Return 0 if it is ok to send an ICMP error response, -1 if we have
960 * hit our bandwidth limit and it is not ok.
961 *
962 * If icmplim is <= 0, the feature is disabled and 0 is returned.
963 *
964 * For now we separate the TCP and UDP subsystems w/ different 'which'
965 * values. We may eventually remove this separation (and simplify the
966 * code further).
967 *
968 * Note that the printing of the error message is delayed so we can
969 * properly print the icmp error rate that the system was trying to do
970 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
971 * the 'final' error, but it doesn't make sense to solve the printing
972 * delay with more complex code.
973 */
974
975 int
976 badport_bandlim(int which)
977 {
978
979 #define N(a) (sizeof (a) / sizeof (a[0]))
980 static struct rate {
981 const char *type;
982 struct timeval lasttime;
983 int curpps;
984 } rates[BANDLIM_MAX+1] = {
985 { "icmp unreach response" },
986 { "icmp ping response" },
987 { "icmp tstamp response" },
988 { "closed port RST response" },
989 { "open port RST response" },
990 { "icmp6 unreach response" },
991 { "sctp ootb response" }
992 };
993
994 /*
995 * Return ok status if feature disabled or argument out of range.
996 */
997 if (V_icmplim > 0 && (u_int) which < N(rates)) {
998 struct rate *r = &rates[which];
999 int opps = r->curpps;
1000
1001 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
1002 return -1; /* discard packet */
1003 /*
1004 * If we've dropped below the threshold after having
1005 * rate-limited traffic print the message. This preserves
1006 * the previous behaviour at the expense of added complexity.
1007 */
1008 if (V_icmplim_output && opps > V_icmplim)
1009 log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
1010 r->type, opps, V_icmplim);
1011 }
1012 return 0; /* okay to send packet */
1013 #undef N
1014 }
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