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MFC r307726:
[FreeBSD/FreeBSD.git] / 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("$FreeBSD$");
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                                 code = PRC_UNREACH_PROTOCOL;
461                                 break;
462                         case ICMP_UNREACH_PORT:
463                                 code = PRC_UNREACH_PORT;
464                                 break;
465
466                         case ICMP_UNREACH_NET_PROHIB:
467                         case ICMP_UNREACH_HOST_PROHIB:
468                         case ICMP_UNREACH_FILTER_PROHIB:
469                                 code = PRC_UNREACH_ADMIN_PROHIB;
470                                 break;
471
472                         default:
473                                 goto badcode;
474                 }
475                 goto deliver;
476
477         case ICMP_TIMXCEED:
478                 if (code > 1)
479                         goto badcode;
480                 code += PRC_TIMXCEED_INTRANS;
481                 goto deliver;
482
483         case ICMP_PARAMPROB:
484                 if (code > 1)
485                         goto badcode;
486                 code = PRC_PARAMPROB;
487         deliver:
488                 /*
489                  * Problem with datagram; advise higher level routines.
490                  */
491                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
492                     icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
493                         ICMPSTAT_INC(icps_badlen);
494                         goto freeit;
495                 }
496                 /* Discard ICMP's in response to multicast packets */
497                 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
498                         goto badcode;
499 #ifdef ICMPPRINTFS
500                 if (icmpprintfs)
501                         printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
502 #endif
503                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
504                 /*
505                  * XXX if the packet contains [IPv4 AH TCP], we can't make a
506                  * notification to TCP layer.
507                  */
508                 i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp));
509                 ip_stripoptions(m);
510                 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
511                         /* This should actually not happen */
512                         ICMPSTAT_INC(icps_tooshort);
513                         return (IPPROTO_DONE);
514                 }
515                 ip = mtod(m, struct ip *);
516                 icp = (struct icmp *)(ip + 1);
517                 /*
518                  * The upper layer handler can rely on:
519                  * - The outer IP header has no options.
520                  * - The outer IP header, the ICMP header, the inner IP header,
521                  *   and the first n bytes of the inner payload are contiguous.
522                  *   n is at least 8, but might be larger based on 
523                  *   ICMP_ADVLENPREF. See its definition in ip_icmp.h.
524                  */
525                 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
526                 if (ctlfunc)
527                         (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
528                                    (void *)&icp->icmp_ip);
529                 break;
530
531         badcode:
532                 ICMPSTAT_INC(icps_badcode);
533                 break;
534
535         case ICMP_ECHO:
536                 if (!V_icmpbmcastecho
537                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
538                         ICMPSTAT_INC(icps_bmcastecho);
539                         break;
540                 }
541                 icp->icmp_type = ICMP_ECHOREPLY;
542                 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
543                         goto freeit;
544                 else
545                         goto reflect;
546
547         case ICMP_TSTAMP:
548                 if (V_icmptstamprepl == 0)
549                         break;
550                 if (!V_icmpbmcastecho
551                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
552                         ICMPSTAT_INC(icps_bmcasttstamp);
553                         break;
554                 }
555                 if (icmplen < ICMP_TSLEN) {
556                         ICMPSTAT_INC(icps_badlen);
557                         break;
558                 }
559                 icp->icmp_type = ICMP_TSTAMPREPLY;
560                 icp->icmp_rtime = iptime();
561                 icp->icmp_ttime = icp->icmp_rtime;      /* bogus, do later! */
562                 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
563                         goto freeit;
564                 else
565                         goto reflect;
566
567         case ICMP_MASKREQ:
568                 if (V_icmpmaskrepl == 0)
569                         break;
570                 /*
571                  * We are not able to respond with all ones broadcast
572                  * unless we receive it over a point-to-point interface.
573                  */
574                 if (icmplen < ICMP_MASKLEN)
575                         break;
576                 switch (ip->ip_dst.s_addr) {
577
578                 case INADDR_BROADCAST:
579                 case INADDR_ANY:
580                         icmpdst.sin_addr = ip->ip_src;
581                         break;
582
583                 default:
584                         icmpdst.sin_addr = ip->ip_dst;
585                 }
586                 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
587                             (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
588                 if (ia == NULL)
589                         break;
590                 if (ia->ia_ifp == NULL) {
591                         ifa_free(&ia->ia_ifa);
592                         break;
593                 }
594                 icp->icmp_type = ICMP_MASKREPLY;
595                 if (V_icmpmaskfake == 0)
596                         icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
597                 else
598                         icp->icmp_mask = V_icmpmaskfake;
599                 if (ip->ip_src.s_addr == 0) {
600                         if (ia->ia_ifp->if_flags & IFF_BROADCAST)
601                             ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
602                         else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
603                             ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
604                 }
605                 ifa_free(&ia->ia_ifa);
606 reflect:
607                 ICMPSTAT_INC(icps_reflect);
608                 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
609                 icmp_reflect(m);
610                 return (IPPROTO_DONE);
611
612         case ICMP_REDIRECT:
613                 if (V_log_redirect) {
614                         u_long src, dst, gw;
615
616                         src = ntohl(ip->ip_src.s_addr);
617                         dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
618                         gw = ntohl(icp->icmp_gwaddr.s_addr);
619                         printf("icmp redirect from %d.%d.%d.%d: "
620                                "%d.%d.%d.%d => %d.%d.%d.%d\n",
621                                (int)(src >> 24), (int)((src >> 16) & 0xff),
622                                (int)((src >> 8) & 0xff), (int)(src & 0xff),
623                                (int)(dst >> 24), (int)((dst >> 16) & 0xff),
624                                (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
625                                (int)(gw >> 24), (int)((gw >> 16) & 0xff),
626                                (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
627                 }
628                 /*
629                  * RFC1812 says we must ignore ICMP redirects if we
630                  * are acting as router.
631                  */
632                 if (V_drop_redirect || V_ipforwarding)
633                         break;
634                 if (code > 3)
635                         goto badcode;
636                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
637                     icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
638                         ICMPSTAT_INC(icps_badlen);
639                         break;
640                 }
641                 /*
642                  * Short circuit routing redirects to force
643                  * immediate change in the kernel's routing
644                  * tables.  The message is also handed to anyone
645                  * listening on a raw socket (e.g. the routing
646                  * daemon for use in updating its tables).
647                  */
648                 icmpgw.sin_addr = ip->ip_src;
649                 icmpdst.sin_addr = icp->icmp_gwaddr;
650 #ifdef  ICMPPRINTFS
651                 if (icmpprintfs) {
652                         char buf[4 * sizeof "123"];
653                         strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
654
655                         printf("redirect dst %s to %s\n",
656                                buf, inet_ntoa(icp->icmp_gwaddr));
657                 }
658 #endif
659                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
660                 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
661                         in_rtredirect((struct sockaddr *)&icmpsrc,
662                           (struct sockaddr *)&icmpdst,
663                           (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
664                           (struct sockaddr *)&icmpgw, fibnum);
665                 }
666                 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
667                 break;
668
669         /*
670          * No kernel processing for the following;
671          * just fall through to send to raw listener.
672          */
673         case ICMP_ECHOREPLY:
674         case ICMP_ROUTERADVERT:
675         case ICMP_ROUTERSOLICIT:
676         case ICMP_TSTAMPREPLY:
677         case ICMP_IREQREPLY:
678         case ICMP_MASKREPLY:
679         case ICMP_SOURCEQUENCH:
680         default:
681                 break;
682         }
683
684 raw:
685         *mp = m;
686         rip_input(mp, offp, proto);
687         return (IPPROTO_DONE);
688
689 freeit:
690         m_freem(m);
691         return (IPPROTO_DONE);
692 }
693
694 /*
695  * Reflect the ip packet back to the source
696  */
697 static void
698 icmp_reflect(struct mbuf *m)
699 {
700         struct rm_priotracker in_ifa_tracker;
701         struct ip *ip = mtod(m, struct ip *);
702         struct ifaddr *ifa;
703         struct ifnet *ifp;
704         struct in_ifaddr *ia;
705         struct in_addr t;
706         struct nhop4_extended nh_ext;
707         struct mbuf *opts = NULL;
708         int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
709
710         if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
711             IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
712             IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
713                 m_freem(m);     /* Bad return address */
714                 ICMPSTAT_INC(icps_badaddr);
715                 goto done;      /* Ip_output() will check for broadcast */
716         }
717
718         t = ip->ip_dst;
719         ip->ip_dst = ip->ip_src;
720
721         /*
722          * Source selection for ICMP replies:
723          *
724          * If the incoming packet was addressed directly to one of our
725          * own addresses, use dst as the src for the reply.
726          */
727         IN_IFADDR_RLOCK(&in_ifa_tracker);
728         LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
729                 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
730                         t = IA_SIN(ia)->sin_addr;
731                         IN_IFADDR_RUNLOCK(&in_ifa_tracker);
732                         goto match;
733                 }
734         }
735         IN_IFADDR_RUNLOCK(&in_ifa_tracker);
736
737         /*
738          * If the incoming packet was addressed to one of our broadcast
739          * addresses, use the first non-broadcast address which corresponds
740          * to the incoming interface.
741          */
742         ifp = m->m_pkthdr.rcvif;
743         if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
744                 IF_ADDR_RLOCK(ifp);
745                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
746                         if (ifa->ifa_addr->sa_family != AF_INET)
747                                 continue;
748                         ia = ifatoia(ifa);
749                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
750                             t.s_addr) {
751                                 t = IA_SIN(ia)->sin_addr;
752                                 IF_ADDR_RUNLOCK(ifp);
753                                 goto match;
754                         }
755                 }
756                 IF_ADDR_RUNLOCK(ifp);
757         }
758         /*
759          * If the packet was transiting through us, use the address of
760          * the interface the packet came through in.  If that interface
761          * doesn't have a suitable IP address, the normal selection
762          * criteria apply.
763          */
764         if (V_icmp_rfi && ifp != NULL) {
765                 IF_ADDR_RLOCK(ifp);
766                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
767                         if (ifa->ifa_addr->sa_family != AF_INET)
768                                 continue;
769                         ia = ifatoia(ifa);
770                         t = IA_SIN(ia)->sin_addr;
771                         IF_ADDR_RUNLOCK(ifp);
772                         goto match;
773                 }
774                 IF_ADDR_RUNLOCK(ifp);
775         }
776         /*
777          * If the incoming packet was not addressed directly to us, use
778          * designated interface for icmp replies specified by sysctl
779          * net.inet.icmp.reply_src (default not set). Otherwise continue
780          * with normal source selection.
781          */
782         if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
783                 IF_ADDR_RLOCK(ifp);
784                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
785                         if (ifa->ifa_addr->sa_family != AF_INET)
786                                 continue;
787                         ia = ifatoia(ifa);
788                         t = IA_SIN(ia)->sin_addr;
789                         IF_ADDR_RUNLOCK(ifp);
790                         goto match;
791                 }
792                 IF_ADDR_RUNLOCK(ifp);
793         }
794         /*
795          * If the packet was transiting through us, use the address of
796          * the interface that is the closest to the packet source.
797          * When we don't have a route back to the packet source, stop here
798          * and drop the packet.
799          */
800         if (fib4_lookup_nh_ext(M_GETFIB(m), ip->ip_dst, 0, 0, &nh_ext) != 0) {
801                 m_freem(m);
802                 ICMPSTAT_INC(icps_noroute);
803                 goto done;
804         }
805         t = nh_ext.nh_src;
806 match:
807 #ifdef MAC
808         mac_netinet_icmp_replyinplace(m);
809 #endif
810         ip->ip_src = t;
811         ip->ip_ttl = V_ip_defttl;
812
813         if (optlen > 0) {
814                 register u_char *cp;
815                 int opt, cnt;
816                 u_int len;
817
818                 /*
819                  * Retrieve any source routing from the incoming packet;
820                  * add on any record-route or timestamp options.
821                  */
822                 cp = (u_char *) (ip + 1);
823                 if ((opts = ip_srcroute(m)) == NULL &&
824                     (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
825                         opts->m_len = sizeof(struct in_addr);
826                         mtod(opts, struct in_addr *)->s_addr = 0;
827                 }
828                 if (opts) {
829 #ifdef ICMPPRINTFS
830                     if (icmpprintfs)
831                             printf("icmp_reflect optlen %d rt %d => ",
832                                 optlen, opts->m_len);
833 #endif
834                     for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
835                             opt = cp[IPOPT_OPTVAL];
836                             if (opt == IPOPT_EOL)
837                                     break;
838                             if (opt == IPOPT_NOP)
839                                     len = 1;
840                             else {
841                                     if (cnt < IPOPT_OLEN + sizeof(*cp))
842                                             break;
843                                     len = cp[IPOPT_OLEN];
844                                     if (len < IPOPT_OLEN + sizeof(*cp) ||
845                                         len > cnt)
846                                             break;
847                             }
848                             /*
849                              * Should check for overflow, but it "can't happen"
850                              */
851                             if (opt == IPOPT_RR || opt == IPOPT_TS ||
852                                 opt == IPOPT_SECURITY) {
853                                     bcopy((caddr_t)cp,
854                                         mtod(opts, caddr_t) + opts->m_len, len);
855                                     opts->m_len += len;
856                             }
857                     }
858                     /* Terminate & pad, if necessary */
859                     cnt = opts->m_len % 4;
860                     if (cnt) {
861                             for (; cnt < 4; cnt++) {
862                                     *(mtod(opts, caddr_t) + opts->m_len) =
863                                         IPOPT_EOL;
864                                     opts->m_len++;
865                             }
866                     }
867 #ifdef ICMPPRINTFS
868                     if (icmpprintfs)
869                             printf("%d\n", opts->m_len);
870 #endif
871                 }
872                 ip_stripoptions(m);
873         }
874         m_tag_delete_nonpersistent(m);
875         m->m_flags &= ~(M_BCAST|M_MCAST);
876         icmp_send(m, opts);
877 done:
878         if (opts)
879                 (void)m_free(opts);
880 }
881
882 /*
883  * Send an icmp packet back to the ip level,
884  * after supplying a checksum.
885  */
886 static void
887 icmp_send(struct mbuf *m, struct mbuf *opts)
888 {
889         register struct ip *ip = mtod(m, struct ip *);
890         register int hlen;
891         register struct icmp *icp;
892
893         hlen = ip->ip_hl << 2;
894         m->m_data += hlen;
895         m->m_len -= hlen;
896         icp = mtod(m, struct icmp *);
897         icp->icmp_cksum = 0;
898         icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
899         m->m_data -= hlen;
900         m->m_len += hlen;
901         m->m_pkthdr.rcvif = (struct ifnet *)0;
902 #ifdef ICMPPRINTFS
903         if (icmpprintfs) {
904                 char buf[4 * sizeof "123"];
905                 strcpy(buf, inet_ntoa(ip->ip_dst));
906                 printf("icmp_send dst %s src %s\n",
907                        buf, inet_ntoa(ip->ip_src));
908         }
909 #endif
910         (void) ip_output(m, opts, NULL, 0, NULL, NULL);
911 }
912
913 /*
914  * Return milliseconds since 00:00 UTC in network format.
915  */
916 uint32_t
917 iptime(void)
918 {
919         struct timeval atv;
920         u_long t;
921
922         getmicrotime(&atv);
923         t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
924         return (htonl(t));
925 }
926
927 /*
928  * Return the next larger or smaller MTU plateau (table from RFC 1191)
929  * given current value MTU.  If DIR is less than zero, a larger plateau
930  * is returned; otherwise, a smaller value is returned.
931  */
932 int
933 ip_next_mtu(int mtu, int dir)
934 {
935         static int mtutab[] = {
936                 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
937                 296, 68, 0
938         };
939         int i, size;
940
941         size = (sizeof mtutab) / (sizeof mtutab[0]);
942         if (dir >= 0) {
943                 for (i = 0; i < size; i++)
944                         if (mtu > mtutab[i])
945                                 return mtutab[i];
946         } else {
947                 for (i = size - 1; i >= 0; i--)
948                         if (mtu < mtutab[i])
949                                 return mtutab[i];
950                 if (mtu == mtutab[0])
951                         return mtutab[0];
952         }
953         return 0;
954 }
955 #endif /* INET */
956
957
958 /*
959  * badport_bandlim() - check for ICMP bandwidth limit
960  *
961  *      Return 0 if it is ok to send an ICMP error response, -1 if we have
962  *      hit our bandwidth limit and it is not ok.
963  *
964  *      If icmplim is <= 0, the feature is disabled and 0 is returned.
965  *
966  *      For now we separate the TCP and UDP subsystems w/ different 'which'
967  *      values.  We may eventually remove this separation (and simplify the
968  *      code further).
969  *
970  *      Note that the printing of the error message is delayed so we can
971  *      properly print the icmp error rate that the system was trying to do
972  *      (i.e. 22000/100 pps, etc...).  This can cause long delays in printing
973  *      the 'final' error, but it doesn't make sense to solve the printing
974  *      delay with more complex code.
975  */
976
977 int
978 badport_bandlim(int which)
979 {
980
981 #define N(a)    (sizeof (a) / sizeof (a[0]))
982         static struct rate {
983                 const char      *type;
984                 struct timeval  lasttime;
985                 int             curpps;
986         } rates[BANDLIM_MAX+1] = {
987                 { "icmp unreach response" },
988                 { "icmp ping response" },
989                 { "icmp tstamp response" },
990                 { "closed port RST response" },
991                 { "open port RST response" },
992                 { "icmp6 unreach response" },
993                 { "sctp ootb response" }
994         };
995
996         /*
997          * Return ok status if feature disabled or argument out of range.
998          */
999         if (V_icmplim > 0 && (u_int) which < N(rates)) {
1000                 struct rate *r = &rates[which];
1001                 int opps = r->curpps;
1002
1003                 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
1004                         return -1;      /* discard packet */
1005                 /*
1006                  * If we've dropped below the threshold after having
1007                  * rate-limited traffic print the message.  This preserves
1008                  * the previous behaviour at the expense of added complexity.
1009                  */
1010                 if (V_icmplim_output && opps > V_icmplim)
1011                         log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
1012                                 r->type, opps, V_icmplim);
1013         }
1014         return 0;                       /* okay to send packet */
1015 #undef N
1016 }