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  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)ip_icmp.c   8.2 (Berkeley) 1/4/94
  34  * $FreeBSD: src/sys/netinet/ip_icmp.c,v 1.39.2.19 2003/01/24 05:11:34 sam Exp $
  35  */
  36
  37 #include "opt_ipsec.h"
  38
  39 #include <sys/param.h>
  40 #include <sys/systm.h>
  41 #include <sys/mbuf.h>
  42 #include <sys/protosw.h>
  43 #include <sys/socket.h>
  44 #include <sys/socketops.h>
  45 #include <sys/time.h>
  46 #include <sys/kernel.h>
  47 #include <sys/sysctl.h>
  48 #include <sys/in_cksum.h>
  49
  50 #include <machine/stdarg.h>
  51
  52 #include <net/if.h>
  53 #include <net/if_types.h>
  54 #include <net/route.h>
  55
  56 #define _IP_VHL
  57 #include <netinet/in.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/icmp_var.h>
  64
  65 #ifdef IPSEC
  66 #include <netinet6/ipsec.h>
  67 #include <netproto/key/key.h>
  68 #endif
  69
  70 #ifdef FAST_IPSEC
  71 #include <netproto/ipsec/ipsec.h>
  72 #include <netproto/ipsec/key.h>
  73 #define IPSEC
  74 #endif
  75
  76 /*
  77  * ICMP routines: error generation, receive packet processing, and
  78  * routines to turnaround packets back to the originator, and
  79  * host table maintenance routines.
  80  */
  81
  82 struct icmpstat icmpstat;
  83 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
  84         &icmpstat, icmpstat, "ICMP statistics");
  85
  86 static int      icmpmaskrepl = 0;
  87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
  88         &icmpmaskrepl, 0, "Allow replies to netmask requests");
  89
  90 static int      drop_redirect = 0;
  91 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
  92         &drop_redirect, 0, "Ignore ICMP redirects");
  93
  94 static int      log_redirect = 0;
  95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
  96         &log_redirect, 0, "Enable output about ICMP redirects");
  97
  98 static int      discard_sourcequench = 1;
  99 SYSCTL_INT(_net_inet_icmp, OID_AUTO, discard_sourcequench, CTLFLAG_RW,
 100         &discard_sourcequench, 0, "Discard ICMP Source Quench");
 101
 102 #ifdef ICMP_BANDLIM
 103
 104 /*
 105  * ICMP error-response bandwidth limiting sysctl.  If not enabled, sysctl
 106  *      variable content is -1 and read-only.
 107  */
 108
 109 static int      icmplim = 200;
 110 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
 111         &icmplim, 0, "ICMP bandwidth limit");
 112 #else
 113
 114 static int      icmplim = -1;
 115 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD,
 116         &icmplim, 0, "ICMP bandwidth limit");
 117
 118 #endif
 119
 120 static int      icmplim_output = 1;
 121 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
 122         &icmplim_output, 0, "Enable output about ICMP bandwidth limits");
 123
 124 /*
 125  * ICMP broadcast echo sysctl
 126  */
 127
 128 static int      icmpbmcastecho = 0;
 129 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
 130     &icmpbmcastecho, 0, "");
 131
 132 static char     icmp_reply_src[IFNAMSIZ];
 133 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
 134         icmp_reply_src, IFNAMSIZ, "icmp reply source for non-local packets.");
 135
 136 static int      icmp_rfi;
 137 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
 138         &icmp_rfi, 0, "ICMP reply from incoming interface for "
 139         "non-local packets");
 140
 141 #ifdef ICMPPRINTFS
 142 int     icmpprintfs = 0;
 143 #endif
 144
 145 static void     icmp_reflect (struct mbuf *);
 146 static void     icmp_send (struct mbuf *, struct mbuf *, struct route *);
 147
 148 extern  struct protosw inetsw[];
 149
 150 /*
 151  * Generate an error packet of type error
 152  * in response to bad packet ip.
 153  */
 154 void
 155 icmp_error(struct mbuf *n, int type, int code, n_long dest, int destmtu)
 156 {
 157         struct ip *oip = mtod(n, struct ip *), *nip;
 158         unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
 159         struct icmp *icp;
 160         struct mbuf *m;
 161         unsigned icmplen;
 162
 163 #ifdef ICMPPRINTFS
 164         if (icmpprintfs)
 165                 kprintf("icmp_error(%p, %d, %d)\n", oip, type, code);
 166 #endif
 167         if (type != ICMP_REDIRECT)
 168                 icmpstat.icps_error++;
 169         /*
 170          * Don't send error if the original packet was encrypted.
 171          * Don't send error if not the first fragment of message.
 172          * Don't error if the old packet protocol was ICMP
 173          * error message, only known informational types.
 174          */
 175         if (n->m_flags & M_DECRYPTED)
 176                 goto freeit;
 177         if (oip->ip_off &~ (IP_MF|IP_DF))
 178                 goto freeit;
 179         if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
 180           n->m_len >= oiplen + ICMP_MINLEN &&
 181           !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
 182                 icmpstat.icps_oldicmp++;
 183                 goto freeit;
 184         }
 185         /* Don't send error in response to a multicast or broadcast packet */
 186         if (n->m_flags & (M_BCAST|M_MCAST))
 187                 goto freeit;
 188         /*
 189          * First, formulate icmp message
 190          */
 191         m = m_gethdr(MB_DONTWAIT, MT_HEADER);
 192         if (m == NULL)
 193                 goto freeit;
 194         icmplen = min(oiplen + 8, oip->ip_len);
 195         if (icmplen < sizeof(struct ip))
 196                 panic("icmp_error: bad length");
 197         m->m_len = icmplen + ICMP_MINLEN;
 198         MH_ALIGN(m, m->m_len);
 199         icp = mtod(m, struct icmp *);
 200         if ((u_int)type > ICMP_MAXTYPE)
 201                 panic("icmp_error");
 202         icmpstat.icps_outhist[type]++;
 203         icp->icmp_type = type;
 204         if (type == ICMP_REDIRECT)
 205                 icp->icmp_gwaddr.s_addr = dest;
 206         else {
 207                 icp->icmp_void = 0;
 208                 /*
 209                  * The following assignments assume an overlay with the
 210                  * zeroed icmp_void field.
 211                  */
 212                 if (type == ICMP_PARAMPROB) {
 213                         icp->icmp_pptr = code;
 214                         code = 0;
 215                 } else if (type == ICMP_UNREACH &&
 216                         code == ICMP_UNREACH_NEEDFRAG && destmtu) {
 217                         icp->icmp_nextmtu = htons(destmtu);
 218                 }
 219         }
 220
 221         icp->icmp_code = code;
 222         m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
 223         nip = &icp->icmp_ip;
 224
 225         /*
 226          * Convert fields to network representation.
 227          */
 228         nip->ip_len = htons(nip->ip_len);
 229         nip->ip_off = htons(nip->ip_off);
 230
 231         /*
 232          * Now, copy old ip header (without options)
 233          * in front of icmp message.
 234          */
 235         if (m->m_data - sizeof(struct ip) < m->m_pktdat)
 236                 panic("icmp len");
 237         m->m_data -= sizeof(struct ip);
 238         m->m_len += sizeof(struct ip);
 239         m->m_pkthdr.len = m->m_len;
 240         m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
 241         nip = mtod(m, struct ip *);
 242         bcopy(oip, nip, sizeof(struct ip));
 243         nip->ip_len = m->m_len;
 244         nip->ip_vhl = IP_VHL_BORING;
 245         nip->ip_p = IPPROTO_ICMP;
 246         nip->ip_tos = 0;
 247         m->m_pkthdr.fw_flags |= n->m_pkthdr.fw_flags & FW_MBUF_GENERATED;
 248         icmp_reflect(m);
 249
 250 freeit:
 251         m_freem(n);
 252 }
 253
 254 /*
 255  * Process a received ICMP message.
 256  */
 257 int
 258 icmp_input(struct mbuf **mp, int *offp, int proto)
 259 {
 260         struct sockaddr_in icmpsrc = { sizeof(struct sockaddr_in), AF_INET };
 261         struct sockaddr_in icmpdst = { sizeof(struct sockaddr_in), AF_INET };
 262         struct sockaddr_in icmpgw = { sizeof(struct sockaddr_in), AF_INET };
 263         struct icmp *icp;
 264         struct in_ifaddr *ia;
 265         struct mbuf *m = *mp;
 266         struct ip *ip = mtod(m, struct ip *);
 267         int icmplen = ip->ip_len;
 268         int i, hlen;
 269         int code;
 270
 271         *mp = NULL;
 272         hlen = *offp;
 273
 274         /*
 275          * Locate icmp structure in mbuf, and check
 276          * that not corrupted and of at least minimum length.
 277          */
 278 #ifdef ICMPPRINTFS
 279         if (icmpprintfs) {
 280                 char buf[sizeof "aaa.bbb.ccc.ddd"];
 281
 282                 strcpy(buf, inet_ntoa(ip->ip_src));
 283                 kprintf("icmp_input from %s to %s, len %d\n",
 284                        buf, inet_ntoa(ip->ip_dst), icmplen);
 285         }
 286 #endif
 287         if (icmplen < ICMP_MINLEN) {
 288                 icmpstat.icps_tooshort++;
 289                 goto freeit;
 290         }
 291         i = hlen + min(icmplen, ICMP_ADVLENMIN);
 292         if (m->m_len < i && (m = m_pullup(m, i)) == NULL)  {
 293                 icmpstat.icps_tooshort++;
 294                 return(IPPROTO_DONE);
 295         }
 296         ip = mtod(m, struct ip *);
 297         m->m_len -= hlen;
 298         m->m_data += hlen;
 299         icp = mtod(m, struct icmp *);
 300         if (in_cksum(m, icmplen)) {
 301                 icmpstat.icps_checksum++;
 302                 goto freeit;
 303         }
 304         m->m_len += hlen;
 305         m->m_data -= hlen;
 306
 307         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
 308                 /*
 309                  * Deliver very specific ICMP type only.
 310                  */
 311                 switch (icp->icmp_type) {
 312                 case ICMP_UNREACH:
 313                 case ICMP_TIMXCEED:
 314                         break;
 315                 default:
 316                         goto freeit;
 317                 }
 318         }
 319
 320 #ifdef ICMPPRINTFS
 321         if (icmpprintfs)
 322                 kprintf("icmp_input, type %d code %d\n", icp->icmp_type,
 323                     icp->icmp_code);
 324 #endif
 325
 326         /*
 327          * Message type specific processing.
 328          */
 329         if (icp->icmp_type > ICMP_MAXTYPE)
 330                 goto raw;
 331         icmpstat.icps_inhist[icp->icmp_type]++;
 332         code = icp->icmp_code;
 333         switch (icp->icmp_type) {
 334
 335         case ICMP_UNREACH:
 336                 switch (code) {
 337                         case ICMP_UNREACH_NET:
 338                         case ICMP_UNREACH_HOST:
 339                         case ICMP_UNREACH_SRCFAIL:
 340                         case ICMP_UNREACH_NET_UNKNOWN:
 341                         case ICMP_UNREACH_HOST_UNKNOWN:
 342                         case ICMP_UNREACH_ISOLATED:
 343                         case ICMP_UNREACH_TOSNET:
 344                         case ICMP_UNREACH_TOSHOST:
 345                         case ICMP_UNREACH_HOST_PRECEDENCE:
 346                         case ICMP_UNREACH_PRECEDENCE_CUTOFF:
 347                                 code = PRC_UNREACH_NET;
 348                                 break;
 349
 350                         case ICMP_UNREACH_NEEDFRAG:
 351                                 code = PRC_MSGSIZE;
 352                                 break;
 353
 354                         /*
 355                          * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
 356                          * Treat subcodes 2,3 as immediate RST
 357                          */
 358                         case ICMP_UNREACH_PROTOCOL:
 359                         case ICMP_UNREACH_PORT:
 360                                 code = PRC_UNREACH_PORT;
 361                                 break;
 362
 363                         case ICMP_UNREACH_NET_PROHIB:
 364                         case ICMP_UNREACH_HOST_PROHIB:
 365                         case ICMP_UNREACH_FILTER_PROHIB:
 366                                 code = PRC_UNREACH_ADMIN_PROHIB;
 367                                 break;
 368
 369                         default:
 370                                 goto badcode;
 371                 }
 372                 goto deliver;
 373
 374         case ICMP_TIMXCEED:
 375                 if (code > 1)
 376                         goto badcode;
 377                 code += PRC_TIMXCEED_INTRANS;
 378                 goto deliver;
 379
 380         case ICMP_PARAMPROB:
 381                 if (code > 1)
 382                         goto badcode;
 383                 code = PRC_PARAMPROB;
 384                 goto deliver;
 385
 386         case ICMP_SOURCEQUENCH:
 387                 if (code)
 388                         goto badcode;
 389                 if (discard_sourcequench)
 390                         break;
 391                 code = PRC_QUENCH;
 392 deliver:
 393                 /*
 394                  * Problem with datagram; advise higher level routines.
 395                  */
 396                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
 397                     IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
 398                         icmpstat.icps_badlen++;
 399                         goto freeit;
 400                 }
 401                 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
 402                 /* Discard ICMP's in response to multicast packets */
 403                 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
 404                         goto badcode;
 405 #ifdef ICMPPRINTFS
 406                 if (icmpprintfs)
 407                         kprintf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
 408 #endif
 409                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
 410 #if 1
 411                 /*
 412                  * MTU discovery:
 413                  * If we got a needfrag and there is a host route to the
 414                  * original destination, and the MTU is not locked, then
 415                  * set the MTU in the route to the suggested new value
 416                  * (if given) and then notify as usual.  The ULPs will
 417                  * notice that the MTU has changed and adapt accordingly.
 418                  * If no new MTU was suggested, then we guess a new one
 419                  * less than the current value.  If the new MTU is
 420                  * unreasonably small (arbitrarily set at 296), then
 421                  * we reset the MTU to the interface value and enable the
 422                  * lock bit, indicating that we are no longer doing MTU
 423                  * discovery.
 424                  */
 425                 if (code == PRC_MSGSIZE) {
 426                         struct rtentry *rt;
 427                         int mtu;
 428
 429                         rt = rtpurelookup((struct sockaddr *)&icmpsrc);
 430                         if (rt != NULL && (rt->rt_flags & RTF_HOST) &&
 431                             !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
 432                                 mtu = ntohs(icp->icmp_nextmtu);
 433                                 if (!mtu)
 434                                         mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
 435                                                           1);
 436 #ifdef DEBUG_MTUDISC
 437                                 kprintf("MTU for %s reduced to %d\n",
 438                                         inet_ntoa(icmpsrc.sin_addr), mtu);
 439 #endif
 440                                 if (mtu < 296) {
 441                                         /* rt->rt_rmx.rmx_mtu =
 442                                                 rt->rt_ifp->if_mtu; */
 443                                         rt->rt_rmx.rmx_locks |= RTV_MTU;
 444                                 } else if (rt->rt_rmx.rmx_mtu > mtu) {
 445                                         rt->rt_rmx.rmx_mtu = mtu;
 446                                 }
 447                         }
 448                         if (rt != NULL)
 449                                 --rt->rt_refcnt;
 450                 }
 451 #endif
 452                 /*
 453                  * XXX if the packet contains [IPv4 AH TCP], we can't make a
 454                  * notification to TCP layer.
 455                  */
 456                 so_pru_ctlinput(
 457                         &inetsw[ip_protox[icp->icmp_ip.ip_p]],
 458                         code, (struct sockaddr *)&icmpsrc, &icp->icmp_ip);
 459                 break;
 460
 461 badcode:
 462                 icmpstat.icps_badcode++;
 463                 break;
 464
 465         case ICMP_ECHO:
 466                 if (!icmpbmcastecho
 467                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
 468                         icmpstat.icps_bmcastecho++;
 469                         break;
 470                 }
 471                 icp->icmp_type = ICMP_ECHOREPLY;
 472 #ifdef ICMP_BANDLIM
 473                 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
 474                         goto freeit;
 475                 else
 476 #endif
 477                         goto reflect;
 478
 479         case ICMP_TSTAMP:
 480                 if (!icmpbmcastecho
 481                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
 482                         icmpstat.icps_bmcasttstamp++;
 483                         break;
 484                 }
 485                 if (icmplen < ICMP_TSLEN) {
 486                         icmpstat.icps_badlen++;
 487                         break;
 488                 }
 489                 icp->icmp_type = ICMP_TSTAMPREPLY;
 490                 icp->icmp_rtime = iptime();
 491                 icp->icmp_ttime = icp->icmp_rtime;      /* bogus, do later! */
 492 #ifdef ICMP_BANDLIM
 493                 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
 494                         goto freeit;
 495                 else
 496 #endif
 497                         goto reflect;
 498
 499         case ICMP_MASKREQ:
 500                 if (icmpmaskrepl == 0)
 501                         break;
 502                 /*
 503                  * We are not able to respond with all ones broadcast
 504                  * unless we receive it over a point-to-point interface.
 505                  */
 506                 if (icmplen < ICMP_MASKLEN)
 507                         break;
 508                 switch (ip->ip_dst.s_addr) {
 509
 510                 case INADDR_BROADCAST:
 511                 case INADDR_ANY:
 512                         icmpdst.sin_addr = ip->ip_src;
 513                         break;
 514
 515                 default:
 516                         icmpdst.sin_addr = ip->ip_dst;
 517                 }
 518                 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
 519                             (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
 520                 if (ia == NULL)
 521                         break;
 522                 if (ia->ia_ifp == 0)
 523                         break;
 524                 icp->icmp_type = ICMP_MASKREPLY;
 525                 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
 526                 if (ip->ip_src.s_addr == 0) {
 527                         if (ia->ia_ifp->if_flags & IFF_BROADCAST)
 528                             ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
 529                         else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
 530                             ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
 531                 }
 532 reflect:
 533                 ip->ip_len += hlen;     /* since ip_input deducts this */
 534                 icmpstat.icps_reflect++;
 535                 icmpstat.icps_outhist[icp->icmp_type]++;
 536                 icmp_reflect(m);
 537                 return(IPPROTO_DONE);
 538
 539         case ICMP_REDIRECT:
 540                 if (log_redirect) {
 541                         u_long src, dst, gw;
 542
 543                         src = ntohl(ip->ip_src.s_addr);
 544                         dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
 545                         gw = ntohl(icp->icmp_gwaddr.s_addr);
 546                         kprintf("icmp redirect from %d.%d.%d.%d: "
 547                                "%d.%d.%d.%d => %d.%d.%d.%d\n",
 548                                (int)(src >> 24), (int)((src >> 16) & 0xff),
 549                                (int)((src >> 8) & 0xff), (int)(src & 0xff),
 550                                (int)(dst >> 24), (int)((dst >> 16) & 0xff),
 551                                (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
 552                                (int)(gw >> 24), (int)((gw >> 16) & 0xff),
 553                                (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
 554                 }
 555                 if (drop_redirect)
 556                         break;
 557                 if (code > 3)
 558                         goto badcode;
 559                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
 560                     IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
 561                         icmpstat.icps_badlen++;
 562                         break;
 563                 }
 564                 /*
 565                  * Short circuit routing redirects to force
 566                  * immediate change in the kernel's routing
 567                  * tables.  The message is also handed to anyone
 568                  * listening on a raw socket (e.g. the routing
 569                  * daemon for use in updating its tables).
 570                  */
 571                 icmpgw.sin_addr = ip->ip_src;
 572                 icmpdst.sin_addr = icp->icmp_gwaddr;
 573 #ifdef  ICMPPRINTFS
 574                 if (icmpprintfs) {
 575                         char buf[sizeof "aaa.bbb.ccc.ddd"];
 576
 577                         strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
 578                         kprintf("redirect dst %s to %s\n",
 579                                buf, inet_ntoa(icp->icmp_gwaddr));
 580                 }
 581 #endif
 582                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
 583                 rtredirect((struct sockaddr *)&icmpsrc,
 584                   (struct sockaddr *)&icmpdst,
 585                   NULL, RTF_GATEWAY | RTF_HOST,
 586                   (struct sockaddr *)&icmpgw);
 587                 kpfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
 588 #ifdef IPSEC
 589                 key_sa_routechange((struct sockaddr *)&icmpsrc);
 590 #endif
 591                 break;
 592
 593         /*
 594          * No kernel processing for the following;
 595          * just fall through to send to raw listener.
 596          */
 597         case ICMP_ECHOREPLY:
 598         case ICMP_ROUTERADVERT:
 599         case ICMP_ROUTERSOLICIT:
 600         case ICMP_TSTAMPREPLY:
 601         case ICMP_IREQREPLY:
 602         case ICMP_MASKREPLY:
 603         default:
 604                 break;
 605         }
 606
 607 raw:
 608         *mp = m;
 609         rip_input(mp, offp, proto);
 610         return(IPPROTO_DONE);
 611
 612 freeit:
 613         m_freem(m);
 614         return(IPPROTO_DONE);
 615 }
 616
 617 /*
 618  * Reflect the ip packet back to the source
 619  */
 620 static void
 621 icmp_reflect(struct mbuf *m)
 622 {
 623         struct ip *ip = mtod(m, struct ip *);
 624         struct in_ifaddr *ia;
 625         struct in_ifaddr_container *iac;
 626         struct ifaddr_container *ifac;
 627         struct ifnet *ifp;
 628         struct in_addr t;
 629         struct mbuf *opts = NULL;
 630         int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
 631         struct route *ro = NULL, rt;
 632
 633         if (!in_canforward(ip->ip_src) &&
 634             ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
 635              (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
 636                 m_freem(m);     /* Bad return address */
 637                 icmpstat.icps_badaddr++;
 638                 goto done;      /* Ip_output() will check for broadcast */
 639         }
 640         t = ip->ip_dst;
 641         ip->ip_dst = ip->ip_src;
 642
 643         ro = &rt;
 644         bzero(ro, sizeof *ro);
 645
 646         /*
 647          * If the incoming packet was addressed directly to us,
 648          * use dst as the src for the reply.  Otherwise (broadcast
 649          * or anonymous), use the address which corresponds
 650          * to the incoming interface.
 651          */
 652         ia = NULL;
 653         LIST_FOREACH(iac, INADDR_HASH(t.s_addr), ia_hash) {
 654                 if (t.s_addr == IA_SIN(iac->ia)->sin_addr.s_addr) {
 655                         ia = iac->ia;
 656                         goto match;
 657                 }
 658         }
 659         ifp = m->m_pkthdr.rcvif;
 660         if (ifp != NULL && (ifp->if_flags & IFF_BROADCAST)) {
 661                 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
 662                         struct ifaddr *ifa = ifac->ifa;
 663
 664                         if (ifa->ifa_addr->sa_family != AF_INET)
 665                                 continue;
 666                         ia = ifatoia(ifa);
 667                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
 668                             t.s_addr)
 669                                 goto match;
 670                 }
 671         }
 672         /*
 673          * If the packet was transiting through us, use the address of
 674          * the interface the packet came through in.  If that interface
 675          * doesn't have a suitable IP address, the normal selection
 676          * criteria apply.
 677          */
 678         if (icmp_rfi && ifp != NULL) {
 679                 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
 680                         struct ifaddr *ifa = ifac->ifa;
 681
 682                         if (ifa->ifa_addr->sa_family != AF_INET)
 683                                 continue;
 684                         ia = ifatoia(ifa);
 685                         goto match;
 686                 }
 687         }
 688         /*
 689          * If the incoming packet was not addressed directly to us, use
 690          * designated interface for icmp replies specified by sysctl
 691          * net.inet.icmp.reply_src (default not set). Otherwise continue
 692          * with normal source selection.
 693          */
 694         if (icmp_reply_src[0] != '\0' && (ifp = ifunit(icmp_reply_src))) {
 695                 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
 696                         struct ifaddr *ifa = ifac->ifa;
 697
 698                         if (ifa->ifa_addr->sa_family != AF_INET)
 699                                 continue;
 700                         ia = ifatoia(ifa);
 701                         goto match;
 702                 }
 703         }
 704         /*
 705          * If the packet was transiting through us, use the address of
 706          * the interface that is the closest to the packet source.
 707          * When we don't have a route back to the packet source, stop here
 708          * and drop the packet.
 709          */
 710         ia = ip_rtaddr(ip->ip_dst, ro);
 711         if (ia == NULL) {
 712                 m_freem(m);
 713                 icmpstat.icps_noroute++;
 714                 goto done;
 715         }
 716 match:
 717         t = IA_SIN(ia)->sin_addr;
 718         ip->ip_src = t;
 719         ip->ip_ttl = ip_defttl;
 720
 721         if (optlen > 0) {
 722                 u_char *cp;
 723                 int opt, cnt;
 724                 u_int len;
 725
 726                 /*
 727                  * Retrieve any source routing from the incoming packet;
 728                  * add on any record-route or timestamp options.
 729                  */
 730                 cp = (u_char *) (ip + 1);
 731                 if ((opts = ip_srcroute(m)) == NULL &&
 732                     (opts = m_gethdr(MB_DONTWAIT, MT_HEADER))) {
 733                         opts->m_len = sizeof(struct in_addr);
 734                         mtod(opts, struct in_addr *)->s_addr = 0;
 735                 }
 736                 if (opts) {
 737 #ifdef ICMPPRINTFS
 738                         if (icmpprintfs)
 739                                 kprintf("icmp_reflect optlen %d rt %d => ",
 740                                        optlen, opts->m_len);
 741 #endif
 742                         for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
 743                                 opt = cp[IPOPT_OPTVAL];
 744                                 if (opt == IPOPT_EOL)
 745                                         break;
 746                                 if (opt == IPOPT_NOP)
 747                                         len = 1;
 748                                 else {
 749                                         if (cnt < IPOPT_OLEN + sizeof *cp)
 750                                                 break;
 751                                         len = cp[IPOPT_OLEN];
 752                                         if (len < IPOPT_OLEN + sizeof *cp ||
 753                                             len > cnt)
 754                                         break;
 755                                 }
 756                                 /*
 757                                  * Should check for overflow, but it
 758                                  * "can't happen".
 759                                  */
 760                                 if (opt == IPOPT_RR || opt == IPOPT_TS ||
 761                                     opt == IPOPT_SECURITY) {
 762                                         bcopy(cp,
 763                                               mtod(opts, caddr_t) + opts->m_len,
 764                                               len);
 765                                         opts->m_len += len;
 766                                 }
 767                         }
 768                         /* Terminate & pad, if necessary */
 769                         cnt = opts->m_len % 4;
 770                         if (cnt) {
 771                                 for (; cnt < 4; cnt++) {
 772                                         *(mtod(opts, caddr_t) + opts->m_len) =
 773                                             IPOPT_EOL;
 774                                         opts->m_len++;
 775                                 }
 776                         }
 777 #ifdef ICMPPRINTFS
 778                         if (icmpprintfs)
 779                                 kprintf("%d\n", opts->m_len);
 780 #endif
 781                 }
 782                 /*
 783                  * Now strip out original options by copying rest of first
 784                  * mbuf's data back, and adjust the IP length.
 785                  */
 786                 ip->ip_len -= optlen;
 787                 ip->ip_vhl = IP_VHL_BORING;
 788                 m->m_len -= optlen;
 789                 if (m->m_flags & M_PKTHDR)
 790                         m->m_pkthdr.len -= optlen;
 791                 optlen += sizeof(struct ip);
 792                 bcopy((caddr_t)ip + optlen, ip + 1,
 793                       m->m_len - sizeof(struct ip));
 794         }
 795         m->m_pkthdr.fw_flags &= FW_MBUF_GENERATED;
 796         m->m_flags &= ~(M_BCAST|M_MCAST);
 797         icmp_send(m, opts, ro);
 798 done:
 799         if (opts)
 800                 m_free(opts);
 801         if (ro && ro->ro_rt)
 802                 RTFREE(ro->ro_rt);
 803 }
 804
 805 /*
 806  * Send an icmp packet back to the ip level,
 807  * after supplying a checksum.
 808  */
 809 static void
 810 icmp_send(struct mbuf *m, struct mbuf *opts, struct route *rt)
 811 {
 812         struct ip *ip = mtod(m, struct ip *);
 813         struct icmp *icp;
 814         int hlen;
 815
 816         hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 817         m->m_data += hlen;
 818         m->m_len -= hlen;
 819         icp = mtod(m, struct icmp *);
 820         icp->icmp_cksum = 0;
 821         icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
 822         m->m_data -= hlen;
 823         m->m_len += hlen;
 824         m->m_pkthdr.rcvif = NULL;
 825 #ifdef ICMPPRINTFS
 826         if (icmpprintfs) {
 827                 char buf[sizeof "aaa.bbb.ccc.ddd"];
 828
 829                 strcpy(buf, inet_ntoa(ip->ip_dst));
 830                 kprintf("icmp_send dst %s src %s\n", buf, inet_ntoa(ip->ip_src));
 831         }
 832 #endif
 833         ip_output(m, opts, rt, 0, NULL, NULL);
 834 }
 835
 836 n_time
 837 iptime(void)
 838 {
 839         struct timeval atv;
 840         u_long t;
 841
 842         getmicrotime(&atv);
 843         t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
 844         return (htonl(t));
 845 }
 846
 847 #if 1
 848 /*
 849  * Return the next larger or smaller MTU plateau (table from RFC 1191)
 850  * given current value MTU.  If DIR is less than zero, a larger plateau
 851  * is returned; otherwise, a smaller value is returned.
 852  */
 853 int
 854 ip_next_mtu(int mtu, int dir)
 855 {
 856         static int mtutab[] = {
 857                 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
 858                 68, 0
 859         };
 860         int i;
 861
 862         for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
 863                 if (mtu >= mtutab[i])
 864                         break;
 865         }
 866
 867         if (dir < 0) {
 868                 if (i == 0) {
 869                         return 0;
 870                 } else {
 871                         return mtutab[i - 1];
 872                 }
 873         } else {
 874                 if (mtutab[i] == 0) {
 875                         return 0;
 876                 } else if(mtu > mtutab[i]) {
 877                         return mtutab[i];
 878                 } else {
 879                         return mtutab[i + 1];
 880                 }
 881         }
 882 }
 883 #endif
 884
 885 #ifdef ICMP_BANDLIM
 886 /*
 887  * badport_bandlim() - check for ICMP bandwidth limit
 888  *
 889  *      Return 0 if it is ok to send an ICMP error response, -1 if we have
 890  *      hit our bandwidth limit and it is not ok.
 891  *
 892  *      If icmplim is <= 0, the feature is disabled and 0 is returned.
 893  *
 894  *      For now we separate the TCP and UDP subsystems w/ different 'which'
 895  *      values.  We may eventually remove this separation (and simplify the
 896  *      code further).
 897  *
 898  *      Note that the printing of the error message is delayed so we can
 899  *      properly print the icmp error rate that the system was trying to do
 900  *      (i.e. 22000/100 pps, etc...).  This can cause long delays in printing
 901  *      the 'final' error, but it doesn't make sense to solve the printing
 902  *      delay with more complex code.
 903  */
 904 int
 905 badport_bandlim(int which)
 906 {
 907         static int lticks[BANDLIM_MAX + 1];
 908         static int lpackets[BANDLIM_MAX + 1];
 909         int dticks;
 910         const char *bandlimittype[] = {
 911                 "Limiting icmp unreach response",
 912                 "Limiting icmp ping response",
 913                 "Limiting icmp tstamp response",
 914                 "Limiting closed port RST response",
 915                 "Limiting open port RST response"
 916                 };
 917
 918         /*
 919          * Return ok status if feature disabled or argument out of
 920          * ranage.
 921          */
 922
 923         if (icmplim <= 0 || which > BANDLIM_MAX || which < 0)
 924                 return(0);
 925         dticks = ticks - lticks[which];
 926
 927         /*
 928          * reset stats when cumulative dt exceeds one second.
 929          */
 930
 931         if ((unsigned int)dticks > hz) {
 932                 if (lpackets[which] > icmplim && icmplim_output) {
 933                         kprintf("%s from %d to %d packets per second\n",
 934                                 bandlimittype[which],
 935                                 lpackets[which],
 936                                 icmplim
 937                         );
 938                 }
 939                 lticks[which] = ticks;
 940                 lpackets[which] = 0;
 941         }
 942
 943         /*
 944          * bump packet count
 945          */
 946
 947         if (++lpackets[which] > icmplim) {
 948                 return(-1);
 949         }
 950         return(0);
 951 }
 952 #endif