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