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 #include "opt_ipsec.h"
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/mbuf.h>
  41 #include <sys/protosw.h>
  42 #include <sys/socket.h>
  43 #include <sys/time.h>
  44 #include <sys/kernel.h>
  45 #include <sys/sysctl.h>
  46 #include <sys/syslog.h>
  47
  48 #include <net/if.h>
  49 #include <net/if_var.h>
  50 #include <net/if_types.h>
  51 #include <net/route.h>
  52 #include <net/vnet.h>
  53
  54 #include <netinet/in.h>
  55 #include <netinet/in_pcb.h>
  56 #include <netinet/in_systm.h>
  57 #include <netinet/in_var.h>
  58 #include <netinet/ip.h>
  59 #include <netinet/ip_icmp.h>
  60 #include <netinet/ip_var.h>
  61 #include <netinet/ip_options.h>
  62 #include <netinet/tcp.h>
  63 #include <netinet/tcp_var.h>
  64 #include <netinet/tcpip.h>
  65 #include <netinet/icmp_var.h>
  66
  67 #ifdef INET
  68 #ifdef IPSEC
  69 #include <netipsec/ipsec.h>
  70 #include <netipsec/key.h>
  71 #endif
  72
  73 #include <machine/in_cksum.h>
  74
  75 #include <security/mac/mac_framework.h>
  76 #endif /* INET */
  77
  78 /*
  79  * ICMP routines: error generation, receive packet processing, and
  80  * routines to turnaround packets back to the originator, and
  81  * host table maintenance routines.
  82  */
  83 static VNET_DEFINE(int, icmplim) = 200;
  84 #define V_icmplim                       VNET(icmplim)
  85 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
  86         &VNET_NAME(icmplim), 0,
  87         "Maximum number of ICMP responses per second");
  88
  89 static VNET_DEFINE(int, icmplim_output) = 1;
  90 #define V_icmplim_output                VNET(icmplim_output)
  91 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
  92         &VNET_NAME(icmplim_output), 0,
  93         "Enable logging of ICMP response rate limiting");
  94
  95 #ifdef INET
  96 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat);
  97 VNET_PCPUSTAT_SYSINIT(icmpstat);
  98 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat,
  99     icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)");
 100
 101 #ifdef VIMAGE
 102 VNET_PCPUSTAT_SYSUNINIT(icmpstat);
 103 #endif /* VIMAGE */
 104
 105 static VNET_DEFINE(int, icmpmaskrepl) = 0;
 106 #define V_icmpmaskrepl                  VNET(icmpmaskrepl)
 107 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
 108         &VNET_NAME(icmpmaskrepl), 0,
 109         "Reply to ICMP Address Mask Request packets.");
 110
 111 static VNET_DEFINE(u_int, icmpmaskfake) = 0;
 112 #define V_icmpmaskfake                  VNET(icmpmaskfake)
 113 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
 114         &VNET_NAME(icmpmaskfake), 0,
 115         "Fake reply to ICMP Address Mask Request packets.");
 116
 117 VNET_DEFINE(int, drop_redirect) = 0;
 118
 119 static VNET_DEFINE(int, log_redirect) = 0;
 120 #define V_log_redirect                  VNET(log_redirect)
 121 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
 122         &VNET_NAME(log_redirect), 0,
 123         "Log ICMP redirects to the console");
 124
 125 static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
 126 #define V_reply_src                     VNET(reply_src)
 127 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
 128         &VNET_NAME(reply_src), IFNAMSIZ,
 129         "icmp reply source for non-local packets.");
 130
 131 static VNET_DEFINE(int, icmp_rfi) = 0;
 132 #define V_icmp_rfi                      VNET(icmp_rfi)
 133 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
 134         &VNET_NAME(icmp_rfi), 0,
 135         "ICMP reply from incoming interface for non-local packets");
 136
 137 static VNET_DEFINE(int, icmp_quotelen) = 8;
 138 #define V_icmp_quotelen                 VNET(icmp_quotelen)
 139 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
 140         &VNET_NAME(icmp_quotelen), 0,
 141         "Number of bytes from original packet to quote in ICMP reply");
 142
 143 /*
 144  * ICMP broadcast echo sysctl
 145  */
 146 static VNET_DEFINE(int, icmpbmcastecho) = 0;
 147 #define V_icmpbmcastecho                VNET(icmpbmcastecho)
 148 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
 149         &VNET_NAME(icmpbmcastecho), 0,
 150         "");
 151
 152
 153 #ifdef ICMPPRINTFS
 154 int     icmpprintfs = 0;
 155 #endif
 156
 157 static void     icmp_reflect(struct mbuf *);
 158 static void     icmp_send(struct mbuf *, struct mbuf *);
 159
 160 extern  struct protosw inetsw[];
 161
 162 static int
 163 sysctl_net_icmp_drop_redir(SYSCTL_HANDLER_ARGS)
 164 {
 165         int error, new;
 166         int i;
 167         struct radix_node_head *rnh;
 168
 169         new = V_drop_redirect;
 170         error = sysctl_handle_int(oidp, &new, 0, req);
 171         if (error == 0 && req->newptr) {
 172                 new = (new != 0) ? 1 : 0;
 173
 174                 if (new == V_drop_redirect)
 175                         return (0);
 176
 177                 for (i = 0; i < rt_numfibs; i++) {
 178                         if ((rnh = rt_tables_get_rnh(i, AF_INET)) == NULL)
 179                                 continue;
 180                         RADIX_NODE_HEAD_LOCK(rnh);
 181                         in_setmatchfunc(rnh, new);
 182                         RADIX_NODE_HEAD_UNLOCK(rnh);
 183                 }
 184
 185                 V_drop_redirect = new;
 186         }
 187
 188         return (error);
 189 }
 190
 191 SYSCTL_VNET_PROC(_net_inet_icmp, OID_AUTO, drop_redirect,
 192     CTLTYPE_INT|CTLFLAG_RW, 0, 0,
 193     sysctl_net_icmp_drop_redir, "I", "Ignore ICMP redirects");
 194
 195 /*
 196  * Kernel module interface for updating icmpstat.  The argument is an index
 197  * into icmpstat treated as an array of u_long.  While this encodes the
 198  * general layout of icmpstat into the caller, it doesn't encode its
 199  * location, so that future changes to add, for example, per-CPU stats
 200  * support won't cause binary compatibility problems for kernel modules.
 201  */
 202 void
 203 kmod_icmpstat_inc(int statnum)
 204 {
 205
 206         counter_u64_add(VNET(icmpstat)[statnum], 1);
 207 }
 208
 209 /*
 210  * Generate an error packet of type error
 211  * in response to bad packet ip.
 212  */
 213 void
 214 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
 215 {
 216         register struct ip *oip = mtod(n, struct ip *), *nip;
 217         register unsigned oiphlen = oip->ip_hl << 2;
 218         register struct icmp *icp;
 219         register struct mbuf *m;
 220         unsigned icmplen, icmpelen, nlen;
 221
 222         KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
 223 #ifdef ICMPPRINTFS
 224         if (icmpprintfs)
 225                 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
 226 #endif
 227         if (type != ICMP_REDIRECT)
 228                 ICMPSTAT_INC(icps_error);
 229         /*
 230          * Don't send error:
 231          *  if the original packet was encrypted.
 232          *  if not the first fragment of message.
 233          *  in response to a multicast or broadcast packet.
 234          *  if the old packet protocol was an ICMP error message.
 235          */
 236         if (n->m_flags & M_DECRYPTED)
 237                 goto freeit;
 238         if (oip->ip_off & htons(~(IP_MF|IP_DF)))
 239                 goto freeit;
 240         if (n->m_flags & (M_BCAST|M_MCAST))
 241                 goto freeit;
 242         if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
 243           n->m_len >= oiphlen + ICMP_MINLEN &&
 244           !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
 245                 ICMPSTAT_INC(icps_oldicmp);
 246                 goto freeit;
 247         }
 248         /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
 249         if (oiphlen + 8 > n->m_len)
 250                 goto freeit;
 251         /*
 252          * Calculate length to quote from original packet and
 253          * prevent the ICMP mbuf from overflowing.
 254          * Unfortunatly this is non-trivial since ip_forward()
 255          * sends us truncated packets.
 256          */
 257         nlen = m_length(n, NULL);
 258         if (oip->ip_p == IPPROTO_TCP) {
 259                 struct tcphdr *th;
 260                 int tcphlen;
 261
 262                 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
 263                     n->m_next == NULL)
 264                         goto stdreply;
 265                 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
 266                     ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
 267                         goto freeit;
 268                 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
 269                 tcphlen = th->th_off << 2;
 270                 if (tcphlen < sizeof(struct tcphdr))
 271                         goto freeit;
 272                 if (ntohs(oip->ip_len) < oiphlen + tcphlen)
 273                         goto freeit;
 274                 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
 275                         goto stdreply;
 276                 if (n->m_len < oiphlen + tcphlen &&
 277                     ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
 278                         goto freeit;
 279                 icmpelen = max(tcphlen, min(V_icmp_quotelen,
 280                     ntohs(oip->ip_len) - oiphlen));
 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 void
 362 icmp_input(struct mbuf *m, int off)
 363 {
 364         struct icmp *icp;
 365         struct in_ifaddr *ia;
 366         struct ip *ip = mtod(m, struct ip *);
 367         struct sockaddr_in icmpsrc, icmpdst, icmpgw;
 368         int hlen = off;
 369         int icmplen = ntohs(ip->ip_len) - off;
 370         int i, code;
 371         void (*ctlfunc)(int, struct sockaddr *, void *);
 372         int fibnum;
 373
 374         /*
 375          * Locate icmp structure in mbuf, and check
 376          * that not corrupted and of at least minimum length.
 377          */
 378 #ifdef ICMPPRINTFS
 379         if (icmpprintfs) {
 380                 char buf[4 * sizeof "123"];
 381                 strcpy(buf, inet_ntoa(ip->ip_src));
 382                 printf("icmp_input from %s to %s, len %d\n",
 383                        buf, inet_ntoa(ip->ip_dst), icmplen);
 384         }
 385 #endif
 386         if (icmplen < ICMP_MINLEN) {
 387                 ICMPSTAT_INC(icps_tooshort);
 388                 goto freeit;
 389         }
 390         i = hlen + min(icmplen, ICMP_ADVLENMIN);
 391         if (m->m_len < i && (m = m_pullup(m, i)) == NULL)  {
 392                 ICMPSTAT_INC(icps_tooshort);
 393                 return;
 394         }
 395         ip = mtod(m, struct ip *);
 396         m->m_len -= hlen;
 397         m->m_data += hlen;
 398         icp = mtod(m, struct icmp *);
 399         if (in_cksum(m, icmplen)) {
 400                 ICMPSTAT_INC(icps_checksum);
 401                 goto freeit;
 402         }
 403         m->m_len += hlen;
 404         m->m_data -= hlen;
 405
 406         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
 407                 /*
 408                  * Deliver very specific ICMP type only.
 409                  */
 410                 switch (icp->icmp_type) {
 411                 case ICMP_UNREACH:
 412                 case ICMP_TIMXCEED:
 413                         break;
 414                 default:
 415                         goto freeit;
 416                 }
 417         }
 418
 419 #ifdef ICMPPRINTFS
 420         if (icmpprintfs)
 421                 printf("icmp_input, type %d code %d\n", icp->icmp_type,
 422                     icp->icmp_code);
 423 #endif
 424
 425         /*
 426          * Message type specific processing.
 427          */
 428         if (icp->icmp_type > ICMP_MAXTYPE)
 429                 goto raw;
 430
 431         /* Initialize */
 432         bzero(&icmpsrc, sizeof(icmpsrc));
 433         icmpsrc.sin_len = sizeof(struct sockaddr_in);
 434         icmpsrc.sin_family = AF_INET;
 435         bzero(&icmpdst, sizeof(icmpdst));
 436         icmpdst.sin_len = sizeof(struct sockaddr_in);
 437         icmpdst.sin_family = AF_INET;
 438         bzero(&icmpgw, sizeof(icmpgw));
 439         icmpgw.sin_len = sizeof(struct sockaddr_in);
 440         icmpgw.sin_family = AF_INET;
 441
 442         ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
 443         code = icp->icmp_code;
 444         switch (icp->icmp_type) {
 445
 446         case ICMP_UNREACH:
 447                 switch (code) {
 448                         case ICMP_UNREACH_NET:
 449                         case ICMP_UNREACH_HOST:
 450                         case ICMP_UNREACH_SRCFAIL:
 451                         case ICMP_UNREACH_NET_UNKNOWN:
 452                         case ICMP_UNREACH_HOST_UNKNOWN:
 453                         case ICMP_UNREACH_ISOLATED:
 454                         case ICMP_UNREACH_TOSNET:
 455                         case ICMP_UNREACH_TOSHOST:
 456                         case ICMP_UNREACH_HOST_PRECEDENCE:
 457                         case ICMP_UNREACH_PRECEDENCE_CUTOFF:
 458                                 code = PRC_UNREACH_NET;
 459                                 break;
 460
 461                         case ICMP_UNREACH_NEEDFRAG:
 462                                 code = PRC_MSGSIZE;
 463                                 break;
 464
 465                         /*
 466                          * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
 467                          * Treat subcodes 2,3 as immediate RST
 468                          */
 469                         case ICMP_UNREACH_PROTOCOL:
 470                         case ICMP_UNREACH_PORT:
 471                                 code = PRC_UNREACH_PORT;
 472                                 break;
 473
 474                         case ICMP_UNREACH_NET_PROHIB:
 475                         case ICMP_UNREACH_HOST_PROHIB:
 476                         case ICMP_UNREACH_FILTER_PROHIB:
 477                                 code = PRC_UNREACH_ADMIN_PROHIB;
 478                                 break;
 479
 480                         default:
 481                                 goto badcode;
 482                 }
 483                 goto deliver;
 484
 485         case ICMP_TIMXCEED:
 486                 if (code > 1)
 487                         goto badcode;
 488                 code += PRC_TIMXCEED_INTRANS;
 489                 goto deliver;
 490
 491         case ICMP_PARAMPROB:
 492                 if (code > 1)
 493                         goto badcode;
 494                 code = PRC_PARAMPROB;
 495                 goto deliver;
 496
 497         case ICMP_SOURCEQUENCH:
 498                 if (code)
 499                         goto badcode;
 500                 code = PRC_QUENCH;
 501         deliver:
 502                 /*
 503                  * Problem with datagram; advise higher level routines.
 504                  */
 505                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
 506                     icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
 507                         ICMPSTAT_INC(icps_badlen);
 508                         goto freeit;
 509                 }
 510                 /* Discard ICMP's in response to multicast packets */
 511                 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
 512                         goto badcode;
 513 #ifdef ICMPPRINTFS
 514                 if (icmpprintfs)
 515                         printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
 516 #endif
 517                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
 518                 /*
 519                  * XXX if the packet contains [IPv4 AH TCP], we can't make a
 520                  * notification to TCP layer.
 521                  */
 522                 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
 523                 if (ctlfunc)
 524                         (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
 525                                    (void *)&icp->icmp_ip);
 526                 break;
 527
 528         badcode:
 529                 ICMPSTAT_INC(icps_badcode);
 530                 break;
 531
 532         case ICMP_ECHO:
 533                 if (!V_icmpbmcastecho
 534                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
 535                         ICMPSTAT_INC(icps_bmcastecho);
 536                         break;
 537                 }
 538                 icp->icmp_type = ICMP_ECHOREPLY;
 539                 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
 540                         goto freeit;
 541                 else
 542                         goto reflect;
 543
 544         case ICMP_TSTAMP:
 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 #ifdef IPSEC
 663                 key_sa_routechange((struct sockaddr *)&icmpsrc);
 664 #endif
 665                 break;
 666
 667         /*
 668          * No kernel processing for the following;
 669          * just fall through to send to raw listener.
 670          */
 671         case ICMP_ECHOREPLY:
 672         case ICMP_ROUTERADVERT:
 673         case ICMP_ROUTERSOLICIT:
 674         case ICMP_TSTAMPREPLY:
 675         case ICMP_IREQREPLY:
 676         case ICMP_MASKREPLY:
 677         default:
 678                 break;
 679         }
 680
 681 raw:
 682         rip_input(m, off);
 683         return;
 684
 685 freeit:
 686         m_freem(m);
 687 }
 688
 689 /*
 690  * Reflect the ip packet back to the source
 691  */
 692 static void
 693 icmp_reflect(struct mbuf *m)
 694 {
 695         struct ip *ip = mtod(m, struct ip *);
 696         struct ifaddr *ifa;
 697         struct ifnet *ifp;
 698         struct in_ifaddr *ia;
 699         struct in_addr t;
 700         struct mbuf *opts = 0;
 701         int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
 702
 703         if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
 704             IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
 705             IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
 706                 m_freem(m);     /* Bad return address */
 707                 ICMPSTAT_INC(icps_badaddr);
 708                 goto done;      /* Ip_output() will check for broadcast */
 709         }
 710
 711         t = ip->ip_dst;
 712         ip->ip_dst = ip->ip_src;
 713
 714         /*
 715          * Source selection for ICMP replies:
 716          *
 717          * If the incoming packet was addressed directly to one of our
 718          * own addresses, use dst as the src for the reply.
 719          */
 720         IN_IFADDR_RLOCK();
 721         LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
 722                 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
 723                         t = IA_SIN(ia)->sin_addr;
 724                         IN_IFADDR_RUNLOCK();
 725                         goto match;
 726                 }
 727         }
 728         IN_IFADDR_RUNLOCK();
 729
 730         /*
 731          * If the incoming packet was addressed to one of our broadcast
 732          * addresses, use the first non-broadcast address which corresponds
 733          * to the incoming interface.
 734          */
 735         ifp = m->m_pkthdr.rcvif;
 736         if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
 737                 IF_ADDR_RLOCK(ifp);
 738                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
 739                         if (ifa->ifa_addr->sa_family != AF_INET)
 740                                 continue;
 741                         ia = ifatoia(ifa);
 742                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
 743                             t.s_addr) {
 744                                 t = IA_SIN(ia)->sin_addr;
 745                                 IF_ADDR_RUNLOCK(ifp);
 746                                 goto match;
 747                         }
 748                 }
 749                 IF_ADDR_RUNLOCK(ifp);
 750         }
 751         /*
 752          * If the packet was transiting through us, use the address of
 753          * the interface the packet came through in.  If that interface
 754          * doesn't have a suitable IP address, the normal selection
 755          * criteria apply.
 756          */
 757         if (V_icmp_rfi && ifp != NULL) {
 758                 IF_ADDR_RLOCK(ifp);
 759                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
 760                         if (ifa->ifa_addr->sa_family != AF_INET)
 761                                 continue;
 762                         ia = ifatoia(ifa);
 763                         t = IA_SIN(ia)->sin_addr;
 764                         IF_ADDR_RUNLOCK(ifp);
 765                         goto match;
 766                 }
 767                 IF_ADDR_RUNLOCK(ifp);
 768         }
 769         /*
 770          * If the incoming packet was not addressed directly to us, use
 771          * designated interface for icmp replies specified by sysctl
 772          * net.inet.icmp.reply_src (default not set). Otherwise continue
 773          * with normal source selection.
 774          */
 775         if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
 776                 IF_ADDR_RLOCK(ifp);
 777                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
 778                         if (ifa->ifa_addr->sa_family != AF_INET)
 779                                 continue;
 780                         ia = ifatoia(ifa);
 781                         t = IA_SIN(ia)->sin_addr;
 782                         IF_ADDR_RUNLOCK(ifp);
 783                         goto match;
 784                 }
 785                 IF_ADDR_RUNLOCK(ifp);
 786         }
 787         /*
 788          * If the packet was transiting through us, use the address of
 789          * the interface that is the closest to the packet source.
 790          * When we don't have a route back to the packet source, stop here
 791          * and drop the packet.
 792          */
 793         ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
 794         if (ia == NULL) {
 795                 m_freem(m);
 796                 ICMPSTAT_INC(icps_noroute);
 797                 goto done;
 798         }
 799         t = IA_SIN(ia)->sin_addr;
 800         ifa_free(&ia->ia_ifa);
 801 match:
 802 #ifdef MAC
 803         mac_netinet_icmp_replyinplace(m);
 804 #endif
 805         ip->ip_src = t;
 806         ip->ip_ttl = V_ip_defttl;
 807
 808         if (optlen > 0) {
 809                 register u_char *cp;
 810                 int opt, cnt;
 811                 u_int len;
 812
 813                 /*
 814                  * Retrieve any source routing from the incoming packet;
 815                  * add on any record-route or timestamp options.
 816                  */
 817                 cp = (u_char *) (ip + 1);
 818                 if ((opts = ip_srcroute(m)) == 0 &&
 819                     (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
 820                         opts->m_len = sizeof(struct in_addr);
 821                         mtod(opts, struct in_addr *)->s_addr = 0;
 822                 }
 823                 if (opts) {
 824 #ifdef ICMPPRINTFS
 825                     if (icmpprintfs)
 826                             printf("icmp_reflect optlen %d rt %d => ",
 827                                 optlen, opts->m_len);
 828 #endif
 829                     for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
 830                             opt = cp[IPOPT_OPTVAL];
 831                             if (opt == IPOPT_EOL)
 832                                     break;
 833                             if (opt == IPOPT_NOP)
 834                                     len = 1;
 835                             else {
 836                                     if (cnt < IPOPT_OLEN + sizeof(*cp))
 837                                             break;
 838                                     len = cp[IPOPT_OLEN];
 839                                     if (len < IPOPT_OLEN + sizeof(*cp) ||
 840                                         len > cnt)
 841                                             break;
 842                             }
 843                             /*
 844                              * Should check for overflow, but it "can't happen"
 845                              */
 846                             if (opt == IPOPT_RR || opt == IPOPT_TS ||
 847                                 opt == IPOPT_SECURITY) {
 848                                     bcopy((caddr_t)cp,
 849                                         mtod(opts, caddr_t) + opts->m_len, len);
 850                                     opts->m_len += len;
 851                             }
 852                     }
 853                     /* Terminate & pad, if necessary */
 854                     cnt = opts->m_len % 4;
 855                     if (cnt) {
 856                             for (; cnt < 4; cnt++) {
 857                                     *(mtod(opts, caddr_t) + opts->m_len) =
 858                                         IPOPT_EOL;
 859                                     opts->m_len++;
 860                             }
 861                     }
 862 #ifdef ICMPPRINTFS
 863                     if (icmpprintfs)
 864                             printf("%d\n", opts->m_len);
 865 #endif
 866                 }
 867                 ip_stripoptions(m);
 868         }
 869         m_tag_delete_nonpersistent(m);
 870         m->m_flags &= ~(M_BCAST|M_MCAST);
 871         icmp_send(m, opts);
 872 done:
 873         if (opts)
 874                 (void)m_free(opts);
 875 }
 876
 877 /*
 878  * Send an icmp packet back to the ip level,
 879  * after supplying a checksum.
 880  */
 881 static void
 882 icmp_send(struct mbuf *m, struct mbuf *opts)
 883 {
 884         register struct ip *ip = mtod(m, struct ip *);
 885         register int hlen;
 886         register struct icmp *icp;
 887
 888         hlen = ip->ip_hl << 2;
 889         m->m_data += hlen;
 890         m->m_len -= hlen;
 891         icp = mtod(m, struct icmp *);
 892         icp->icmp_cksum = 0;
 893         icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
 894         m->m_data -= hlen;
 895         m->m_len += hlen;
 896         m->m_pkthdr.rcvif = (struct ifnet *)0;
 897 #ifdef ICMPPRINTFS
 898         if (icmpprintfs) {
 899                 char buf[4 * sizeof "123"];
 900                 strcpy(buf, inet_ntoa(ip->ip_dst));
 901                 printf("icmp_send dst %s src %s\n",
 902                        buf, inet_ntoa(ip->ip_src));
 903         }
 904 #endif
 905         (void) ip_output(m, opts, NULL, 0, NULL, NULL);
 906 }
 907
 908 /*
 909  * Return milliseconds since 00:00 GMT in network format.
 910  */
 911 uint32_t
 912 iptime(void)
 913 {
 914         struct timeval atv;
 915         u_long t;
 916
 917         getmicrotime(&atv);
 918         t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
 919         return (htonl(t));
 920 }
 921
 922 /*
 923  * Return the next larger or smaller MTU plateau (table from RFC 1191)
 924  * given current value MTU.  If DIR is less than zero, a larger plateau
 925  * is returned; otherwise, a smaller value is returned.
 926  */
 927 int
 928 ip_next_mtu(int mtu, int dir)
 929 {
 930         static int mtutab[] = {
 931                 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
 932                 296, 68, 0
 933         };
 934         int i, size;
 935
 936         size = (sizeof mtutab) / (sizeof mtutab[0]);
 937         if (dir >= 0) {
 938                 for (i = 0; i < size; i++)
 939                         if (mtu > mtutab[i])
 940                                 return mtutab[i];
 941         } else {
 942                 for (i = size - 1; i >= 0; i--)
 943                         if (mtu < mtutab[i])
 944                                 return mtutab[i];
 945                 if (mtu == mtutab[0])
 946                         return mtutab[0];
 947         }
 948         return 0;
 949 }
 950 #endif /* INET */
 951
 952
 953 /*
 954  * badport_bandlim() - check for ICMP bandwidth limit
 955  *
 956  *      Return 0 if it is ok to send an ICMP error response, -1 if we have
 957  *      hit our bandwidth limit and it is not ok.
 958  *
 959  *      If icmplim is <= 0, the feature is disabled and 0 is returned.
 960  *
 961  *      For now we separate the TCP and UDP subsystems w/ different 'which'
 962  *      values.  We may eventually remove this separation (and simplify the
 963  *      code further).
 964  *
 965  *      Note that the printing of the error message is delayed so we can
 966  *      properly print the icmp error rate that the system was trying to do
 967  *      (i.e. 22000/100 pps, etc...).  This can cause long delays in printing
 968  *      the 'final' error, but it doesn't make sense to solve the printing
 969  *      delay with more complex code.
 970  */
 971
 972 int
 973 badport_bandlim(int which)
 974 {
 975
 976 #define N(a)    (sizeof (a) / sizeof (a[0]))
 977         static struct rate {
 978                 const char      *type;
 979                 struct timeval  lasttime;
 980                 int             curpps;
 981         } rates[BANDLIM_MAX+1] = {
 982                 { "icmp unreach response" },
 983                 { "icmp ping response" },
 984                 { "icmp tstamp response" },
 985                 { "closed port RST response" },
 986                 { "open port RST response" },
 987                 { "icmp6 unreach response" },
 988                 { "sctp ootb response" }
 989         };
 990
 991         /*
 992          * Return ok status if feature disabled or argument out of range.
 993          */
 994         if (V_icmplim > 0 && (u_int) which < N(rates)) {
 995                 struct rate *r = &rates[which];
 996                 int opps = r->curpps;
 997
 998                 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
 999                         return -1;      /* discard packet */
1000                 /*
1001                  * If we've dropped below the threshold after having
1002                  * rate-limited traffic print the message.  This preserves
1003                  * the previous behaviour at the expense of added complexity.
1004                  */
1005                 if (V_icmplim_output && opps > V_icmplim)
1006                         log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
1007                                 r->type, opps, V_icmplim);
1008         }
1009         return 0;                       /* okay to send packet */
1010 #undef N
1011 }