1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1988, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include "opt_inet.h"
38
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/mbuf.h>
42 #include <sys/protosw.h>
43 #include <sys/socket.h>
44 #include <sys/time.h>
45 #include <sys/kernel.h>
46 #include <sys/lock.h>
47 #include <sys/rmlock.h>
48 #include <sys/sysctl.h>
49 #include <sys/syslog.h>
50
51 #include <net/if.h>
52 #include <net/if_var.h>
53 #include <net/if_types.h>
54 #include <net/route.h>
55 #include <net/vnet.h>
56
57 #include <netinet/in.h>
58 #include <netinet/in_fib.h>
59 #include <netinet/in_pcb.h>
60 #include <netinet/in_systm.h>
61 #include <netinet/in_var.h>
62 #include <netinet/ip.h>
63 #include <netinet/ip_icmp.h>
64 #include <netinet/ip_var.h>
65 #include <netinet/ip_options.h>
66 #include <netinet/sctp.h>
67 #include <netinet/tcp.h>
68 #include <netinet/tcp_var.h>
69 #include <netinet/tcpip.h>
70 #include <netinet/icmp_var.h>
71
72
73 #ifdef INET
74
75 #include <machine/in_cksum.h>
76
77 #include <security/mac/mac_framework.h>
78 #endif /* INET */
79
80 /*
81 * ICMP routines: error generation, receive packet processing, and
82 * routines to turnaround packets back to the originator, and
83 * host table maintenance routines.
84 */
85 VNET_DEFINE_STATIC(int, icmplim) = 200;
86 #define V_icmplim VNET(icmplim)
87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW,
88 &VNET_NAME(icmplim), 0,
89 "Maximum number of ICMP responses per second");
90
91 VNET_DEFINE_STATIC(int, icmplim_output) = 1;
92 #define V_icmplim_output VNET(icmplim_output)
93 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW,
94 &VNET_NAME(icmplim_output), 0,
95 "Enable logging of ICMP response rate limiting");
96
97 #ifdef INET
98 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat);
99 VNET_PCPUSTAT_SYSINIT(icmpstat);
100 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat,
101 icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)");
102
103 #ifdef VIMAGE
104 VNET_PCPUSTAT_SYSUNINIT(icmpstat);
105 #endif /* VIMAGE */
106
107 VNET_DEFINE_STATIC(int, icmpmaskrepl) = 0;
108 #define V_icmpmaskrepl VNET(icmpmaskrepl)
109 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW,
110 &VNET_NAME(icmpmaskrepl), 0,
111 "Reply to ICMP Address Mask Request packets");
112
113 VNET_DEFINE_STATIC(u_int, icmpmaskfake) = 0;
114 #define V_icmpmaskfake VNET(icmpmaskfake)
115 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW,
116 &VNET_NAME(icmpmaskfake), 0,
117 "Fake reply to ICMP Address Mask Request packets");
118
119 VNET_DEFINE(int, drop_redirect) = 0;
120 #define V_drop_redirect VNET(drop_redirect)
121 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW,
122 &VNET_NAME(drop_redirect), 0,
123 "Ignore ICMP redirects");
124
125 VNET_DEFINE_STATIC(int, log_redirect) = 0;
126 #define V_log_redirect VNET(log_redirect)
127 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW,
128 &VNET_NAME(log_redirect), 0,
129 "Log ICMP redirects to the console");
130
131 VNET_DEFINE_STATIC(char, reply_src[IFNAMSIZ]);
132 #define V_reply_src VNET(reply_src)
133 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW,
134 &VNET_NAME(reply_src), IFNAMSIZ,
135 "ICMP reply source for non-local packets");
136
137 VNET_DEFINE_STATIC(int, icmp_rfi) = 0;
138 #define V_icmp_rfi VNET(icmp_rfi)
139 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW,
140 &VNET_NAME(icmp_rfi), 0,
141 "ICMP reply from incoming interface for non-local packets");
142 /* Router requirements RFC 1812 section 4.3.2.3 requires 576 - 28. */
143 VNET_DEFINE_STATIC(int, icmp_quotelen) = 548;
144 #define V_icmp_quotelen VNET(icmp_quotelen)
145 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW,
146 &VNET_NAME(icmp_quotelen), 0,
147 "Number of bytes from original packet to quote in ICMP reply");
148
149 VNET_DEFINE_STATIC(int, icmpbmcastecho) = 0;
150 #define V_icmpbmcastecho VNET(icmpbmcastecho)
151 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW,
152 &VNET_NAME(icmpbmcastecho), 0,
153 "Reply to multicast ICMP Echo Request and Timestamp packets");
154
155 VNET_DEFINE_STATIC(int, icmptstamprepl) = 1;
156 #define V_icmptstamprepl VNET(icmptstamprepl)
157 SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_VNET | CTLFLAG_RW,
158 &VNET_NAME(icmptstamprepl), 0,
159 "Respond to ICMP Timestamp packets");
160
161 VNET_DEFINE_STATIC(int, error_keeptags) = 0;
162 #define V_error_keeptags VNET(error_keeptags)
163 SYSCTL_INT(_net_inet_icmp, OID_AUTO, error_keeptags, CTLFLAG_VNET | CTLFLAG_RW,
164 &VNET_NAME(error_keeptags), 0,
165 "ICMP error response keeps copy of mbuf_tags of original packet");
166
167 #ifdef ICMPPRINTFS
168 int icmpprintfs = 0;
169 #endif
170
171 static void icmp_reflect(struct mbuf *);
172 static void icmp_send(struct mbuf *, struct mbuf *);
173
174 extern struct protosw inetsw[];
175
176 /*
177 * Kernel module interface for updating icmpstat. The argument is an index
178 * into icmpstat treated as an array of u_long. While this encodes the
179 * general layout of icmpstat into the caller, it doesn't encode its
180 * location, so that future changes to add, for example, per-CPU stats
181 * support won't cause binary compatibility problems for kernel modules.
182 */
183 void
kmod_icmpstat_inc(int statnum)184 kmod_icmpstat_inc(int statnum)
185 {
186
187 counter_u64_add(VNET(icmpstat)[statnum], 1);
188 }
189
190 /*
191 * Generate an error packet of type error
192 * in response to bad packet ip.
193 */
194 void
icmp_error(struct mbuf * n,int type,int code,uint32_t dest,int mtu)195 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
196 {
197 struct ip *oip, *nip;
198 struct icmp *icp;
199 struct mbuf *m;
200 unsigned icmplen, icmpelen, nlen, oiphlen;
201
202 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type",
203 __func__));
204
205 if (type != ICMP_REDIRECT)
206 ICMPSTAT_INC(icps_error);
207 /*
208 * Don't send error:
209 * if the original packet was encrypted.
210 * if not the first fragment of message.
211 * in response to a multicast or broadcast packet.
212 * if the old packet protocol was an ICMP error message.
213 */
214 if (n->m_flags & M_DECRYPTED)
215 goto freeit;
216 if (n->m_flags & (M_BCAST|M_MCAST))
217 goto freeit;
218
219 /* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */
220 if (n->m_len < sizeof(struct ip) + ICMP_MINLEN)
221 goto freeit;
222 oip = mtod(n, struct ip *);
223 oiphlen = oip->ip_hl << 2;
224 if (n->m_len < oiphlen + ICMP_MINLEN)
225 goto freeit;
226 #ifdef ICMPPRINTFS
227 if (icmpprintfs)
228 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
229 #endif
230 if (oip->ip_off & htons(~(IP_MF|IP_DF)))
231 goto freeit;
232 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
233 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip +
234 oiphlen))->icmp_type)) {
235 ICMPSTAT_INC(icps_oldicmp);
236 goto freeit;
237 }
238 /*
239 * Calculate length to quote from original packet and
240 * prevent the ICMP mbuf from overflowing.
241 * Unfortunately this is non-trivial since ip_forward()
242 * sends us truncated packets.
243 */
244 nlen = m_length(n, NULL);
245 if (oip->ip_p == IPPROTO_TCP) {
246 struct tcphdr *th;
247 int tcphlen;
248
249 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
250 n->m_next == NULL)
251 goto stdreply;
252 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
253 (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)
254 goto freeit;
255 oip = mtod(n, struct ip *);
256 th = mtodo(n, oiphlen);
257 tcphlen = th->th_off << 2;
258 if (tcphlen < sizeof(struct tcphdr))
259 goto freeit;
260 if (ntohs(oip->ip_len) < oiphlen + tcphlen)
261 goto freeit;
262 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
263 goto stdreply;
264 if (n->m_len < oiphlen + tcphlen &&
265 (n = m_pullup(n, oiphlen + tcphlen)) == NULL)
266 goto freeit;
267 icmpelen = max(tcphlen, min(V_icmp_quotelen,
268 ntohs(oip->ip_len) - oiphlen));
269 } else if (oip->ip_p == IPPROTO_SCTP) {
270 struct sctphdr *sh;
271 struct sctp_chunkhdr *ch;
272
273 if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr))
274 goto stdreply;
275 if (oiphlen + sizeof(struct sctphdr) > n->m_len &&
276 n->m_next == NULL)
277 goto stdreply;
278 if (n->m_len < oiphlen + sizeof(struct sctphdr) &&
279 (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL)
280 goto freeit;
281 oip = mtod(n, struct ip *);
282 icmpelen = max(sizeof(struct sctphdr),
283 min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
284 sh = mtodo(n, oiphlen);
285 if (ntohl(sh->v_tag) == 0 &&
286 ntohs(oip->ip_len) >= oiphlen +
287 sizeof(struct sctphdr) + 8 &&
288 (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 ||
289 n->m_next != NULL)) {
290 if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 &&
291 (n = m_pullup(n, oiphlen +
292 sizeof(struct sctphdr) + 8)) == NULL)
293 goto freeit;
294 oip = mtod(n, struct ip *);
295 sh = mtodo(n, oiphlen);
296 ch = (struct sctp_chunkhdr *)(sh + 1);
297 if (ch->chunk_type == SCTP_INITIATION) {
298 icmpelen = max(sizeof(struct sctphdr) + 8,
299 min(V_icmp_quotelen, ntohs(oip->ip_len) -
300 oiphlen));
301 }
302 }
303 } else
304 stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) -
305 oiphlen));
306
307 icmplen = min(oiphlen + icmpelen, nlen);
308 if (icmplen < sizeof(struct ip))
309 goto freeit;
310
311 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
312 m = m_gethdr(M_NOWAIT, MT_DATA);
313 else
314 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
315 if (m == NULL)
316 goto freeit;
317 #ifdef MAC
318 mac_netinet_icmp_reply(n, m);
319 #endif
320 icmplen = min(icmplen, M_TRAILINGSPACE(m) -
321 sizeof(struct ip) - ICMP_MINLEN);
322 m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen);
323 m->m_data += sizeof(struct ip);
324 m->m_len = ICMP_MINLEN + icmplen;
325
326 /* XXX MRT make the outgoing packet use the same FIB
327 * that was associated with the incoming packet
328 */
329 M_SETFIB(m, M_GETFIB(n));
330 icp = mtod(m, struct icmp *);
331 ICMPSTAT_INC(icps_outhist[type]);
332 icp->icmp_type = type;
333 if (type == ICMP_REDIRECT)
334 icp->icmp_gwaddr.s_addr = dest;
335 else {
336 icp->icmp_void = 0;
337 /*
338 * The following assignments assume an overlay with the
339 * just zeroed icmp_void field.
340 */
341 if (type == ICMP_PARAMPROB) {
342 icp->icmp_pptr = code;
343 code = 0;
344 } else if (type == ICMP_UNREACH &&
345 code == ICMP_UNREACH_NEEDFRAG && mtu) {
346 icp->icmp_nextmtu = htons(mtu);
347 }
348 }
349 icp->icmp_code = code;
350
351 /*
352 * Copy the quotation into ICMP message and
353 * convert quoted IP header back to network representation.
354 */
355 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
356 nip = &icp->icmp_ip;
357
358 /*
359 * Set up ICMP message mbuf and copy old IP header (without options
360 * in front of ICMP message.
361 * If the original mbuf was meant to bypass the firewall, the error
362 * reply should bypass as well.
363 */
364 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
365 KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip),
366 ("insufficient space for ip header"));
367 m->m_data -= sizeof(struct ip);
368 m->m_len += sizeof(struct ip);
369 m->m_pkthdr.len = m->m_len;
370 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
371 nip = mtod(m, struct ip *);
372 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
373 nip->ip_len = htons(m->m_len);
374 nip->ip_v = IPVERSION;
375 nip->ip_hl = 5;
376 nip->ip_p = IPPROTO_ICMP;
377 nip->ip_tos = 0;
378 nip->ip_off = 0;
379
380 if (V_error_keeptags)
381 m_tag_copy_chain(m, n, M_NOWAIT);
382
383 icmp_reflect(m);
384
385 freeit:
386 m_freem(n);
387 }
388
389 /*
390 * Process a received ICMP message.
391 */
392 int
icmp_input(struct mbuf ** mp,int * offp,int proto)393 icmp_input(struct mbuf **mp, int *offp, int proto)
394 {
395 struct icmp *icp;
396 struct in_ifaddr *ia;
397 struct mbuf *m = *mp;
398 struct ip *ip = mtod(m, struct ip *);
399 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
400 int hlen = *offp;
401 int icmplen = ntohs(ip->ip_len) - *offp;
402 int i, code;
403 void (*ctlfunc)(int, struct sockaddr *, void *);
404 int fibnum;
405
406 *mp = NULL;
407
408 /*
409 * Locate icmp structure in mbuf, and check
410 * that not corrupted and of at least minimum length.
411 */
412 #ifdef ICMPPRINTFS
413 if (icmpprintfs) {
414 char srcbuf[INET_ADDRSTRLEN];
415 char dstbuf[INET_ADDRSTRLEN];
416
417 printf("icmp_input from %s to %s, len %d\n",
418 inet_ntoa_r(ip->ip_src, srcbuf),
419 inet_ntoa_r(ip->ip_dst, dstbuf), icmplen);
420 }
421 #endif
422 NET_EPOCH_ENTER();
423 if (icmplen < ICMP_MINLEN) {
424 ICMPSTAT_INC(icps_tooshort);
425 goto freeit;
426 }
427 i = hlen + min(icmplen, ICMP_ADVLENMIN);
428 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
429 ICMPSTAT_INC(icps_tooshort);
430 NET_EPOCH_EXIT();
431 return (IPPROTO_DONE);
432 }
433 ip = mtod(m, struct ip *);
434 m->m_len -= hlen;
435 m->m_data += hlen;
436 icp = mtod(m, struct icmp *);
437 if (in_cksum(m, icmplen)) {
438 ICMPSTAT_INC(icps_checksum);
439 goto freeit;
440 }
441 m->m_len += hlen;
442 m->m_data -= hlen;
443
444 #ifdef ICMPPRINTFS
445 if (icmpprintfs)
446 printf("icmp_input, type %d code %d\n", icp->icmp_type,
447 icp->icmp_code);
448 #endif
449
450 /*
451 * Message type specific processing.
452 */
453 if (icp->icmp_type > ICMP_MAXTYPE)
454 goto raw;
455
456 /* Initialize */
457 bzero(&icmpsrc, sizeof(icmpsrc));
458 icmpsrc.sin_len = sizeof(struct sockaddr_in);
459 icmpsrc.sin_family = AF_INET;
460 bzero(&icmpdst, sizeof(icmpdst));
461 icmpdst.sin_len = sizeof(struct sockaddr_in);
462 icmpdst.sin_family = AF_INET;
463 bzero(&icmpgw, sizeof(icmpgw));
464 icmpgw.sin_len = sizeof(struct sockaddr_in);
465 icmpgw.sin_family = AF_INET;
466
467 ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
468 code = icp->icmp_code;
469 switch (icp->icmp_type) {
470
471 case ICMP_UNREACH:
472 switch (code) {
473 case ICMP_UNREACH_NET:
474 case ICMP_UNREACH_HOST:
475 case ICMP_UNREACH_SRCFAIL:
476 case ICMP_UNREACH_NET_UNKNOWN:
477 case ICMP_UNREACH_HOST_UNKNOWN:
478 case ICMP_UNREACH_ISOLATED:
479 case ICMP_UNREACH_TOSNET:
480 case ICMP_UNREACH_TOSHOST:
481 case ICMP_UNREACH_HOST_PRECEDENCE:
482 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
483 code = PRC_UNREACH_NET;
484 break;
485
486 case ICMP_UNREACH_NEEDFRAG:
487 code = PRC_MSGSIZE;
488 break;
489
490 /*
491 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
492 * Treat subcodes 2,3 as immediate RST
493 */
494 case ICMP_UNREACH_PROTOCOL:
495 code = PRC_UNREACH_PROTOCOL;
496 break;
497 case ICMP_UNREACH_PORT:
498 code = PRC_UNREACH_PORT;
499 break;
500
501 case ICMP_UNREACH_NET_PROHIB:
502 case ICMP_UNREACH_HOST_PROHIB:
503 case ICMP_UNREACH_FILTER_PROHIB:
504 code = PRC_UNREACH_ADMIN_PROHIB;
505 break;
506
507 default:
508 goto badcode;
509 }
510 goto deliver;
511
512 case ICMP_TIMXCEED:
513 if (code > 1)
514 goto badcode;
515 code += PRC_TIMXCEED_INTRANS;
516 goto deliver;
517
518 case ICMP_PARAMPROB:
519 if (code > 1)
520 goto badcode;
521 code = PRC_PARAMPROB;
522 deliver:
523 /*
524 * Problem with datagram; advise higher level routines.
525 */
526 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
527 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
528 ICMPSTAT_INC(icps_badlen);
529 goto freeit;
530 }
531 /* Discard ICMP's in response to multicast packets */
532 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
533 goto badcode;
534 #ifdef ICMPPRINTFS
535 if (icmpprintfs)
536 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
537 #endif
538 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
539 /*
540 * XXX if the packet contains [IPv4 AH TCP], we can't make a
541 * notification to TCP layer.
542 */
543 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp));
544 ip_stripoptions(m);
545 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
546 /* This should actually not happen */
547 ICMPSTAT_INC(icps_tooshort);
548 NET_EPOCH_EXIT();
549 return (IPPROTO_DONE);
550 }
551 ip = mtod(m, struct ip *);
552 icp = (struct icmp *)(ip + 1);
553 /*
554 * The upper layer handler can rely on:
555 * - The outer IP header has no options.
556 * - The outer IP header, the ICMP header, the inner IP header,
557 * and the first n bytes of the inner payload are contiguous.
558 * n is at least 8, but might be larger based on
559 * ICMP_ADVLENPREF. See its definition in ip_icmp.h.
560 */
561 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
562 if (ctlfunc)
563 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
564 (void *)&icp->icmp_ip);
565 break;
566
567 badcode:
568 ICMPSTAT_INC(icps_badcode);
569 break;
570
571 case ICMP_ECHO:
572 if (!V_icmpbmcastecho
573 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
574 ICMPSTAT_INC(icps_bmcastecho);
575 break;
576 }
577 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
578 goto freeit;
579 icp->icmp_type = ICMP_ECHOREPLY;
580 goto reflect;
581
582 case ICMP_TSTAMP:
583 if (V_icmptstamprepl == 0)
584 break;
585 if (!V_icmpbmcastecho
586 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
587 ICMPSTAT_INC(icps_bmcasttstamp);
588 break;
589 }
590 if (icmplen < ICMP_TSLEN) {
591 ICMPSTAT_INC(icps_badlen);
592 break;
593 }
594 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
595 goto freeit;
596 icp->icmp_type = ICMP_TSTAMPREPLY;
597 icp->icmp_rtime = iptime();
598 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
599 goto reflect;
600
601 case ICMP_MASKREQ:
602 if (V_icmpmaskrepl == 0)
603 break;
604 /*
605 * We are not able to respond with all ones broadcast
606 * unless we receive it over a point-to-point interface.
607 */
608 if (icmplen < ICMP_MASKLEN)
609 break;
610 switch (ip->ip_dst.s_addr) {
611
612 case INADDR_BROADCAST:
613 case INADDR_ANY:
614 icmpdst.sin_addr = ip->ip_src;
615 break;
616
617 default:
618 icmpdst.sin_addr = ip->ip_dst;
619 }
620 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
621 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
622 if (ia == NULL)
623 break;
624 if (ia->ia_ifp == NULL)
625 break;
626 icp->icmp_type = ICMP_MASKREPLY;
627 if (V_icmpmaskfake == 0)
628 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
629 else
630 icp->icmp_mask = V_icmpmaskfake;
631 if (ip->ip_src.s_addr == 0) {
632 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
633 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
634 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
635 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
636 }
637 reflect:
638 ICMPSTAT_INC(icps_reflect);
639 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
640 icmp_reflect(m);
641 NET_EPOCH_EXIT();
642 return (IPPROTO_DONE);
643
644 case ICMP_REDIRECT:
645 if (V_log_redirect) {
646 u_long src, dst, gw;
647
648 src = ntohl(ip->ip_src.s_addr);
649 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
650 gw = ntohl(icp->icmp_gwaddr.s_addr);
651 printf("icmp redirect from %d.%d.%d.%d: "
652 "%d.%d.%d.%d => %d.%d.%d.%d\n",
653 (int)(src >> 24), (int)((src >> 16) & 0xff),
654 (int)((src >> 8) & 0xff), (int)(src & 0xff),
655 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
656 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
657 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
658 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
659 }
660 /*
661 * RFC1812 says we must ignore ICMP redirects if we
662 * are acting as router.
663 */
664 if (V_drop_redirect || V_ipforwarding)
665 break;
666 if (code > 3)
667 goto badcode;
668 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
669 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
670 ICMPSTAT_INC(icps_badlen);
671 break;
672 }
673 /*
674 * Short circuit routing redirects to force
675 * immediate change in the kernel's routing
676 * tables. The message is also handed to anyone
677 * listening on a raw socket (e.g. the routing
678 * daemon for use in updating its tables).
679 */
680 icmpgw.sin_addr = ip->ip_src;
681 icmpdst.sin_addr = icp->icmp_gwaddr;
682 #ifdef ICMPPRINTFS
683 if (icmpprintfs) {
684 char dstbuf[INET_ADDRSTRLEN];
685 char gwbuf[INET_ADDRSTRLEN];
686
687 printf("redirect dst %s to %s\n",
688 inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf),
689 inet_ntoa_r(icp->icmp_gwaddr, gwbuf));
690 }
691 #endif
692 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
693 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
694 in_rtredirect((struct sockaddr *)&icmpsrc,
695 (struct sockaddr *)&icmpdst,
696 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
697 (struct sockaddr *)&icmpgw, fibnum);
698 }
699 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
700 break;
701
702 /*
703 * No kernel processing for the following;
704 * just fall through to send to raw listener.
705 */
706 case ICMP_ECHOREPLY:
707 case ICMP_ROUTERADVERT:
708 case ICMP_ROUTERSOLICIT:
709 case ICMP_TSTAMPREPLY:
710 case ICMP_IREQREPLY:
711 case ICMP_MASKREPLY:
712 case ICMP_SOURCEQUENCH:
713 default:
714 break;
715 }
716
717 raw:
718 NET_EPOCH_EXIT();
719 *mp = m;
720 rip_input(mp, offp, proto);
721 return (IPPROTO_DONE);
722
723 freeit:
724 NET_EPOCH_EXIT();
725 m_freem(m);
726 return (IPPROTO_DONE);
727 }
728
729 /*
730 * Reflect the ip packet back to the source
731 */
732 static void
icmp_reflect(struct mbuf * m)733 icmp_reflect(struct mbuf *m)
734 {
735 struct rm_priotracker in_ifa_tracker;
736 struct ip *ip = mtod(m, struct ip *);
737 struct ifaddr *ifa;
738 struct ifnet *ifp;
739 struct in_ifaddr *ia;
740 struct in_addr t;
741 struct nhop4_extended nh_ext;
742 struct mbuf *opts = NULL;
743 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
744
745 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
746 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
747 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
748 m_freem(m); /* Bad return address */
749 ICMPSTAT_INC(icps_badaddr);
750 goto done; /* Ip_output() will check for broadcast */
751 }
752
753 t = ip->ip_dst;
754 ip->ip_dst = ip->ip_src;
755
756 /*
757 * Source selection for ICMP replies:
758 *
759 * If the incoming packet was addressed directly to one of our
760 * own addresses, use dst as the src for the reply.
761 */
762 IN_IFADDR_RLOCK(&in_ifa_tracker);
763 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
764 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
765 t = IA_SIN(ia)->sin_addr;
766 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
767 goto match;
768 }
769 }
770 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
771
772 /*
773 * If the incoming packet was addressed to one of our broadcast
774 * addresses, use the first non-broadcast address which corresponds
775 * to the incoming interface.
776 */
777 ifp = m->m_pkthdr.rcvif;
778 if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
779 IF_ADDR_RLOCK(ifp);
780 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
781 if (ifa->ifa_addr->sa_family != AF_INET)
782 continue;
783 ia = ifatoia(ifa);
784 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
785 t.s_addr) {
786 t = IA_SIN(ia)->sin_addr;
787 IF_ADDR_RUNLOCK(ifp);
788 goto match;
789 }
790 }
791 IF_ADDR_RUNLOCK(ifp);
792 }
793 /*
794 * If the packet was transiting through us, use the address of
795 * the interface the packet came through in. If that interface
796 * doesn't have a suitable IP address, the normal selection
797 * criteria apply.
798 */
799 if (V_icmp_rfi && ifp != NULL) {
800 IF_ADDR_RLOCK(ifp);
801 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
802 if (ifa->ifa_addr->sa_family != AF_INET)
803 continue;
804 ia = ifatoia(ifa);
805 t = IA_SIN(ia)->sin_addr;
806 IF_ADDR_RUNLOCK(ifp);
807 goto match;
808 }
809 IF_ADDR_RUNLOCK(ifp);
810 }
811 /*
812 * If the incoming packet was not addressed directly to us, use
813 * designated interface for icmp replies specified by sysctl
814 * net.inet.icmp.reply_src (default not set). Otherwise continue
815 * with normal source selection.
816 */
817 if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
818 IF_ADDR_RLOCK(ifp);
819 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
820 if (ifa->ifa_addr->sa_family != AF_INET)
821 continue;
822 ia = ifatoia(ifa);
823 t = IA_SIN(ia)->sin_addr;
824 IF_ADDR_RUNLOCK(ifp);
825 goto match;
826 }
827 IF_ADDR_RUNLOCK(ifp);
828 }
829 /*
830 * If the packet was transiting through us, use the address of
831 * the interface that is the closest to the packet source.
832 * When we don't have a route back to the packet source, stop here
833 * and drop the packet.
834 */
835 if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) {
836 m_freem(m);
837 ICMPSTAT_INC(icps_noroute);
838 goto done;
839 }
840 t = nh_ext.nh_src;
841 match:
842 #ifdef MAC
843 mac_netinet_icmp_replyinplace(m);
844 #endif
845 ip->ip_src = t;
846 ip->ip_ttl = V_ip_defttl;
847
848 if (optlen > 0) {
849 u_char *cp;
850 int opt, cnt;
851 u_int len;
852
853 /*
854 * Retrieve any source routing from the incoming packet;
855 * add on any record-route or timestamp options.
856 */
857 cp = (u_char *) (ip + 1);
858 if ((opts = ip_srcroute(m)) == NULL &&
859 (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
860 opts->m_len = sizeof(struct in_addr);
861 mtod(opts, struct in_addr *)->s_addr = 0;
862 }
863 if (opts) {
864 #ifdef ICMPPRINTFS
865 if (icmpprintfs)
866 printf("icmp_reflect optlen %d rt %d => ",
867 optlen, opts->m_len);
868 #endif
869 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
870 opt = cp[IPOPT_OPTVAL];
871 if (opt == IPOPT_EOL)
872 break;
873 if (opt == IPOPT_NOP)
874 len = 1;
875 else {
876 if (cnt < IPOPT_OLEN + sizeof(*cp))
877 break;
878 len = cp[IPOPT_OLEN];
879 if (len < IPOPT_OLEN + sizeof(*cp) ||
880 len > cnt)
881 break;
882 }
883 /*
884 * Should check for overflow, but it "can't happen"
885 */
886 if (opt == IPOPT_RR || opt == IPOPT_TS ||
887 opt == IPOPT_SECURITY) {
888 bcopy((caddr_t)cp,
889 mtod(opts, caddr_t) + opts->m_len, len);
890 opts->m_len += len;
891 }
892 }
893 /* Terminate & pad, if necessary */
894 cnt = opts->m_len % 4;
895 if (cnt) {
896 for (; cnt < 4; cnt++) {
897 *(mtod(opts, caddr_t) + opts->m_len) =
898 IPOPT_EOL;
899 opts->m_len++;
900 }
901 }
902 #ifdef ICMPPRINTFS
903 if (icmpprintfs)
904 printf("%d\n", opts->m_len);
905 #endif
906 }
907 ip_stripoptions(m);
908 }
909 m_tag_delete_nonpersistent(m);
910 m->m_flags &= ~(M_BCAST|M_MCAST);
911 icmp_send(m, opts);
912 done:
913 if (opts)
914 (void)m_free(opts);
915 }
916
917 /*
918 * Send an icmp packet back to the ip level,
919 * after supplying a checksum.
920 */
921 static void
icmp_send(struct mbuf * m,struct mbuf * opts)922 icmp_send(struct mbuf *m, struct mbuf *opts)
923 {
924 struct ip *ip = mtod(m, struct ip *);
925 int hlen;
926 struct icmp *icp;
927
928 hlen = ip->ip_hl << 2;
929 m->m_data += hlen;
930 m->m_len -= hlen;
931 icp = mtod(m, struct icmp *);
932 icp->icmp_cksum = 0;
933 icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
934 m->m_data -= hlen;
935 m->m_len += hlen;
936 m->m_pkthdr.rcvif = (struct ifnet *)0;
937 #ifdef ICMPPRINTFS
938 if (icmpprintfs) {
939 char dstbuf[INET_ADDRSTRLEN];
940 char srcbuf[INET_ADDRSTRLEN];
941
942 printf("icmp_send dst %s src %s\n",
943 inet_ntoa_r(ip->ip_dst, dstbuf),
944 inet_ntoa_r(ip->ip_src, srcbuf));
945 }
946 #endif
947 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
948 }
949
950 /*
951 * Return milliseconds since 00:00 UTC in network format.
952 */
953 uint32_t
iptime(void)954 iptime(void)
955 {
956 struct timeval atv;
957 u_long t;
958
959 getmicrotime(&atv);
960 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
961 return (htonl(t));
962 }
963
964 /*
965 * Return the next larger or smaller MTU plateau (table from RFC 1191)
966 * given current value MTU. If DIR is less than zero, a larger plateau
967 * is returned; otherwise, a smaller value is returned.
968 */
969 int
ip_next_mtu(int mtu,int dir)970 ip_next_mtu(int mtu, int dir)
971 {
972 static int mtutab[] = {
973 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
974 296, 68, 0
975 };
976 int i, size;
977
978 size = (sizeof mtutab) / (sizeof mtutab[0]);
979 if (dir >= 0) {
980 for (i = 0; i < size; i++)
981 if (mtu > mtutab[i])
982 return mtutab[i];
983 } else {
984 for (i = size - 1; i >= 0; i--)
985 if (mtu < mtutab[i])
986 return mtutab[i];
987 if (mtu == mtutab[0])
988 return mtutab[0];
989 }
990 return 0;
991 }
992 #endif /* INET */
993
994
995 /*
996 * badport_bandlim() - check for ICMP bandwidth limit
997 *
998 * Return 0 if it is ok to send an ICMP error response, -1 if we have
999 * hit our bandwidth limit and it is not ok.
1000 *
1001 * If icmplim is <= 0, the feature is disabled and 0 is returned.
1002 *
1003 * For now we separate the TCP and UDP subsystems w/ different 'which'
1004 * values. We may eventually remove this separation (and simplify the
1005 * code further).
1006 *
1007 * Note that the printing of the error message is delayed so we can
1008 * properly print the icmp error rate that the system was trying to do
1009 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
1010 * the 'final' error, but it doesn't make sense to solve the printing
1011 * delay with more complex code.
1012 */
1013 struct icmp_rate {
1014 const char *descr;
1015 struct counter_rate cr;
1016 };
1017 VNET_DEFINE_STATIC(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = {
1018 { "icmp unreach response" },
1019 { "icmp ping response" },
1020 { "icmp tstamp response" },
1021 { "closed port RST response" },
1022 { "open port RST response" },
1023 { "icmp6 unreach response" },
1024 { "sctp ootb response" }
1025 };
1026 #define V_icmp_rates VNET(icmp_rates)
1027
1028 static void
icmp_bandlimit_init(void)1029 icmp_bandlimit_init(void)
1030 {
1031
1032 for (int i = 0; i < BANDLIM_MAX; i++) {
1033 V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK);
1034 V_icmp_rates[i].cr.cr_ticks = ticks;
1035 }
1036 }
1037 VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY,
1038 icmp_bandlimit_init, NULL);
1039
1040 static void
icmp_bandlimit_uninit(void)1041 icmp_bandlimit_uninit(void)
1042 {
1043
1044 for (int i = 0; i < BANDLIM_MAX; i++)
1045 counter_u64_free(V_icmp_rates[i].cr.cr_rate);
1046 }
1047 VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1048 icmp_bandlimit_uninit, NULL);
1049
1050 int
badport_bandlim(int which)1051 badport_bandlim(int which)
1052 {
1053 int64_t pps;
1054
1055 if (V_icmplim == 0 || which == BANDLIM_UNLIMITED)
1056 return (0);
1057
1058 KASSERT(which >= 0 && which < BANDLIM_MAX,
1059 ("%s: which %d", __func__, which));
1060
1061 pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim);
1062 if (pps == -1)
1063 return (-1);
1064 if (pps > 0 && V_icmplim_output)
1065 log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n",
1066 V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim);
1067 return (0);
1068 }
1069