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