The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_icmp.c

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    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: releng/10.1/sys/netinet/ip_icmp.c 264221 2014-04-07 12:50:08Z ae $");
   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 logging of ICMP response rate limiting");
   93 
   94 #ifdef INET
   95 VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat);
   96 VNET_PCPUSTAT_SYSINIT(icmpstat);
   97 SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat,
   98     icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)");
   99 
  100 #ifdef VIMAGE
  101 VNET_PCPUSTAT_SYSUNINIT(icmpstat);
  102 #endif /* VIMAGE */
  103 
  104 static VNET_DEFINE(int, icmpmaskrepl) = 0;
  105 #define V_icmpmaskrepl                  VNET(icmpmaskrepl)
  106 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
  107         &VNET_NAME(icmpmaskrepl), 0,
  108         "Reply to ICMP Address Mask Request packets.");
  109 
  110 static VNET_DEFINE(u_int, icmpmaskfake) = 0;
  111 #define V_icmpmaskfake                  VNET(icmpmaskfake)
  112 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
  113         &VNET_NAME(icmpmaskfake), 0,
  114         "Fake reply to ICMP Address Mask Request packets.");
  115 
  116 VNET_DEFINE(int, drop_redirect) = 0;
  117 
  118 static VNET_DEFINE(int, log_redirect) = 0;
  119 #define V_log_redirect                  VNET(log_redirect)
  120 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
  121         &VNET_NAME(log_redirect), 0,
  122         "Log ICMP redirects to the console");
  123 
  124 static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
  125 #define V_reply_src                     VNET(reply_src)
  126 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
  127         &VNET_NAME(reply_src), IFNAMSIZ,
  128         "icmp reply source for non-local packets.");
  129 
  130 static VNET_DEFINE(int, icmp_rfi) = 0;
  131 #define V_icmp_rfi                      VNET(icmp_rfi)
  132 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
  133         &VNET_NAME(icmp_rfi), 0,
  134         "ICMP reply from incoming interface for non-local packets");
  135 
  136 static VNET_DEFINE(int, icmp_quotelen) = 8;
  137 #define V_icmp_quotelen                 VNET(icmp_quotelen)
  138 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
  139         &VNET_NAME(icmp_quotelen), 0,
  140         "Number of bytes from original packet to quote in ICMP reply");
  141 
  142 /*
  143  * ICMP broadcast echo sysctl
  144  */
  145 static VNET_DEFINE(int, icmpbmcastecho) = 0;
  146 #define V_icmpbmcastecho                VNET(icmpbmcastecho)
  147 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
  148         &VNET_NAME(icmpbmcastecho), 0,
  149         "");
  150 
  151 
  152 #ifdef ICMPPRINTFS
  153 int     icmpprintfs = 0;
  154 #endif
  155 
  156 static void     icmp_reflect(struct mbuf *);
  157 static void     icmp_send(struct mbuf *, struct mbuf *);
  158 
  159 extern  struct protosw inetsw[];
  160 
  161 static int
  162 sysctl_net_icmp_drop_redir(SYSCTL_HANDLER_ARGS)
  163 {
  164         int error, new;
  165         int i;
  166         struct radix_node_head *rnh;
  167 
  168         new = V_drop_redirect;
  169         error = sysctl_handle_int(oidp, &new, 0, req);
  170         if (error == 0 && req->newptr) {
  171                 new = (new != 0) ? 1 : 0;
  172 
  173                 if (new == V_drop_redirect)
  174                         return (0);
  175 
  176                 for (i = 0; i < rt_numfibs; i++) {
  177                         if ((rnh = rt_tables_get_rnh(i, AF_INET)) == NULL)
  178                                 continue;
  179                         RADIX_NODE_HEAD_LOCK(rnh);
  180                         in_setmatchfunc(rnh, new);
  181                         RADIX_NODE_HEAD_UNLOCK(rnh);
  182                 }
  183                 
  184                 V_drop_redirect = new;
  185         }
  186 
  187         return (error);
  188 }
  189 
  190 SYSCTL_VNET_PROC(_net_inet_icmp, OID_AUTO, drop_redirect,
  191     CTLTYPE_INT|CTLFLAG_RW, 0, 0,
  192     sysctl_net_icmp_drop_redir, "I", "Ignore ICMP redirects");
  193 
  194 /*
  195  * Kernel module interface for updating icmpstat.  The argument is an index
  196  * into icmpstat treated as an array of u_long.  While this encodes the
  197  * general layout of icmpstat into the caller, it doesn't encode its
  198  * location, so that future changes to add, for example, per-CPU stats
  199  * support won't cause binary compatibility problems for kernel modules.
  200  */
  201 void
  202 kmod_icmpstat_inc(int statnum)
  203 {
  204 
  205         counter_u64_add(VNET(icmpstat)[statnum], 1);
  206 }
  207 
  208 /*
  209  * Generate an error packet of type error
  210  * in response to bad packet ip.
  211  */
  212 void
  213 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
  214 {
  215         register struct ip *oip = mtod(n, struct ip *), *nip;
  216         register unsigned oiphlen = oip->ip_hl << 2;
  217         register struct icmp *icp;
  218         register struct mbuf *m;
  219         unsigned icmplen, icmpelen, nlen;
  220 
  221         KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
  222 #ifdef ICMPPRINTFS
  223         if (icmpprintfs)
  224                 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
  225 #endif
  226         if (type != ICMP_REDIRECT)
  227                 ICMPSTAT_INC(icps_error);
  228         /*
  229          * Don't send error:
  230          *  if the original packet was encrypted.
  231          *  if not the first fragment of message.
  232          *  in response to a multicast or broadcast packet.
  233          *  if the old packet protocol was an ICMP error message.
  234          */
  235         if (n->m_flags & M_DECRYPTED)
  236                 goto freeit;
  237         if (oip->ip_off & htons(~(IP_MF|IP_DF)))
  238                 goto freeit;
  239         if (n->m_flags & (M_BCAST|M_MCAST))
  240                 goto freeit;
  241         if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
  242           n->m_len >= oiphlen + ICMP_MINLEN &&
  243           !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
  244                 ICMPSTAT_INC(icps_oldicmp);
  245                 goto freeit;
  246         }
  247         /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
  248         if (oiphlen + 8 > n->m_len)
  249                 goto freeit;
  250         /*
  251          * Calculate length to quote from original packet and
  252          * prevent the ICMP mbuf from overflowing.
  253          * Unfortunatly this is non-trivial since ip_forward()
  254          * sends us truncated packets.
  255          */
  256         nlen = m_length(n, NULL);
  257         if (oip->ip_p == IPPROTO_TCP) {
  258                 struct tcphdr *th;
  259                 int tcphlen;
  260 
  261                 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
  262                     n->m_next == NULL)
  263                         goto stdreply;
  264                 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
  265                     ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
  266                         goto freeit;
  267                 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
  268                 tcphlen = th->th_off << 2;
  269                 if (tcphlen < sizeof(struct tcphdr))
  270                         goto freeit;
  271                 if (ntohs(oip->ip_len) < oiphlen + tcphlen)
  272                         goto freeit;
  273                 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
  274                         goto stdreply;
  275                 if (n->m_len < oiphlen + tcphlen && 
  276                     ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
  277                         goto freeit;
  278                 icmpelen = max(tcphlen, min(V_icmp_quotelen,
  279                     ntohs(oip->ip_len) - oiphlen));
  280         } else
  281 stdreply:       icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
  282 
  283         icmplen = min(oiphlen + icmpelen, nlen);
  284         if (icmplen < sizeof(struct ip))
  285                 goto freeit;
  286 
  287         if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
  288                 m = m_gethdr(M_NOWAIT, MT_DATA);
  289         else
  290                 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
  291         if (m == NULL)
  292                 goto freeit;
  293 #ifdef MAC
  294         mac_netinet_icmp_reply(n, m);
  295 #endif
  296         icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
  297         m_align(m, ICMP_MINLEN + icmplen);
  298         m->m_len = ICMP_MINLEN + icmplen;
  299 
  300         /* XXX MRT  make the outgoing packet use the same FIB
  301          * that was associated with the incoming packet
  302          */
  303         M_SETFIB(m, M_GETFIB(n));
  304         icp = mtod(m, struct icmp *);
  305         ICMPSTAT_INC(icps_outhist[type]);
  306         icp->icmp_type = type;
  307         if (type == ICMP_REDIRECT)
  308                 icp->icmp_gwaddr.s_addr = dest;
  309         else {
  310                 icp->icmp_void = 0;
  311                 /*
  312                  * The following assignments assume an overlay with the
  313                  * just zeroed icmp_void field.
  314                  */
  315                 if (type == ICMP_PARAMPROB) {
  316                         icp->icmp_pptr = code;
  317                         code = 0;
  318                 } else if (type == ICMP_UNREACH &&
  319                         code == ICMP_UNREACH_NEEDFRAG && mtu) {
  320                         icp->icmp_nextmtu = htons(mtu);
  321                 }
  322         }
  323         icp->icmp_code = code;
  324 
  325         /*
  326          * Copy the quotation into ICMP message and
  327          * convert quoted IP header back to network representation.
  328          */
  329         m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
  330         nip = &icp->icmp_ip;
  331 
  332         /*
  333          * Set up ICMP message mbuf and copy old IP header (without options
  334          * in front of ICMP message.
  335          * If the original mbuf was meant to bypass the firewall, the error
  336          * reply should bypass as well.
  337          */
  338         m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
  339         m->m_data -= sizeof(struct ip);
  340         m->m_len += sizeof(struct ip);
  341         m->m_pkthdr.len = m->m_len;
  342         m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
  343         nip = mtod(m, struct ip *);
  344         bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
  345         nip->ip_len = htons(m->m_len);
  346         nip->ip_v = IPVERSION;
  347         nip->ip_hl = 5;
  348         nip->ip_p = IPPROTO_ICMP;
  349         nip->ip_tos = 0;
  350         nip->ip_off = 0;
  351         icmp_reflect(m);
  352 
  353 freeit:
  354         m_freem(n);
  355 }
  356 
  357 /*
  358  * Process a received ICMP message.
  359  */
  360 void
  361 icmp_input(struct mbuf *m, int off)
  362 {
  363         struct icmp *icp;
  364         struct in_ifaddr *ia;
  365         struct ip *ip = mtod(m, struct ip *);
  366         struct sockaddr_in icmpsrc, icmpdst, icmpgw;
  367         int hlen = off;
  368         int icmplen = ntohs(ip->ip_len) - off;
  369         int i, code;
  370         void (*ctlfunc)(int, struct sockaddr *, void *);
  371         int fibnum;
  372 
  373         /*
  374          * Locate icmp structure in mbuf, and check
  375          * that not corrupted and of at least minimum length.
  376          */
  377 #ifdef ICMPPRINTFS
  378         if (icmpprintfs) {
  379                 char buf[4 * sizeof "123"];
  380                 strcpy(buf, inet_ntoa(ip->ip_src));
  381                 printf("icmp_input from %s to %s, len %d\n",
  382                        buf, inet_ntoa(ip->ip_dst), icmplen);
  383         }
  384 #endif
  385         if (icmplen < ICMP_MINLEN) {
  386                 ICMPSTAT_INC(icps_tooshort);
  387                 goto freeit;
  388         }
  389         i = hlen + min(icmplen, ICMP_ADVLENMIN);
  390         if (m->m_len < i && (m = m_pullup(m, i)) == NULL)  {
  391                 ICMPSTAT_INC(icps_tooshort);
  392                 return;
  393         }
  394         ip = mtod(m, struct ip *);
  395         m->m_len -= hlen;
  396         m->m_data += hlen;
  397         icp = mtod(m, struct icmp *);
  398         if (in_cksum(m, icmplen)) {
  399                 ICMPSTAT_INC(icps_checksum);
  400                 goto freeit;
  401         }
  402         m->m_len += hlen;
  403         m->m_data -= hlen;
  404 
  405         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
  406                 /*
  407                  * Deliver very specific ICMP type only.
  408                  */
  409                 switch (icp->icmp_type) {
  410                 case ICMP_UNREACH:
  411                 case ICMP_TIMXCEED:
  412                         break;
  413                 default:
  414                         goto freeit;
  415                 }
  416         }
  417 
  418 #ifdef ICMPPRINTFS
  419         if (icmpprintfs)
  420                 printf("icmp_input, type %d code %d\n", icp->icmp_type,
  421                     icp->icmp_code);
  422 #endif
  423 
  424         /*
  425          * Message type specific processing.
  426          */
  427         if (icp->icmp_type > ICMP_MAXTYPE)
  428                 goto raw;
  429 
  430         /* Initialize */
  431         bzero(&icmpsrc, sizeof(icmpsrc));
  432         icmpsrc.sin_len = sizeof(struct sockaddr_in);
  433         icmpsrc.sin_family = AF_INET;
  434         bzero(&icmpdst, sizeof(icmpdst));
  435         icmpdst.sin_len = sizeof(struct sockaddr_in);
  436         icmpdst.sin_family = AF_INET;
  437         bzero(&icmpgw, sizeof(icmpgw));
  438         icmpgw.sin_len = sizeof(struct sockaddr_in);
  439         icmpgw.sin_family = AF_INET;
  440 
  441         ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
  442         code = icp->icmp_code;
  443         switch (icp->icmp_type) {
  444 
  445         case ICMP_UNREACH:
  446                 switch (code) {
  447                         case ICMP_UNREACH_NET:
  448                         case ICMP_UNREACH_HOST:
  449                         case ICMP_UNREACH_SRCFAIL:
  450                         case ICMP_UNREACH_NET_UNKNOWN:
  451                         case ICMP_UNREACH_HOST_UNKNOWN:
  452                         case ICMP_UNREACH_ISOLATED:
  453                         case ICMP_UNREACH_TOSNET:
  454                         case ICMP_UNREACH_TOSHOST:
  455                         case ICMP_UNREACH_HOST_PRECEDENCE:
  456                         case ICMP_UNREACH_PRECEDENCE_CUTOFF:
  457                                 code = PRC_UNREACH_NET;
  458                                 break;
  459 
  460                         case ICMP_UNREACH_NEEDFRAG:
  461                                 code = PRC_MSGSIZE;
  462                                 break;
  463 
  464                         /*
  465                          * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
  466                          * Treat subcodes 2,3 as immediate RST
  467                          */
  468                         case ICMP_UNREACH_PROTOCOL:
  469                         case ICMP_UNREACH_PORT:
  470                                 code = PRC_UNREACH_PORT;
  471                                 break;
  472 
  473                         case ICMP_UNREACH_NET_PROHIB:
  474                         case ICMP_UNREACH_HOST_PROHIB:
  475                         case ICMP_UNREACH_FILTER_PROHIB:
  476                                 code = PRC_UNREACH_ADMIN_PROHIB;
  477                                 break;
  478 
  479                         default:
  480                                 goto badcode;
  481                 }
  482                 goto deliver;
  483 
  484         case ICMP_TIMXCEED:
  485                 if (code > 1)
  486                         goto badcode;
  487                 code += PRC_TIMXCEED_INTRANS;
  488                 goto deliver;
  489 
  490         case ICMP_PARAMPROB:
  491                 if (code > 1)
  492                         goto badcode;
  493                 code = PRC_PARAMPROB;
  494                 goto deliver;
  495 
  496         case ICMP_SOURCEQUENCH:
  497                 if (code)
  498                         goto badcode;
  499                 code = PRC_QUENCH;
  500         deliver:
  501                 /*
  502                  * Problem with datagram; advise higher level routines.
  503                  */
  504                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
  505                     icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
  506                         ICMPSTAT_INC(icps_badlen);
  507                         goto freeit;
  508                 }
  509                 /* Discard ICMP's in response to multicast packets */
  510                 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
  511                         goto badcode;
  512 #ifdef ICMPPRINTFS
  513                 if (icmpprintfs)
  514                         printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
  515 #endif
  516                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
  517                 /*
  518                  * XXX if the packet contains [IPv4 AH TCP], we can't make a
  519                  * notification to TCP layer.
  520                  */
  521                 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
  522                 if (ctlfunc)
  523                         (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
  524                                    (void *)&icp->icmp_ip);
  525                 break;
  526 
  527         badcode:
  528                 ICMPSTAT_INC(icps_badcode);
  529                 break;
  530 
  531         case ICMP_ECHO:
  532                 if (!V_icmpbmcastecho
  533                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
  534                         ICMPSTAT_INC(icps_bmcastecho);
  535                         break;
  536                 }
  537                 icp->icmp_type = ICMP_ECHOREPLY;
  538                 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
  539                         goto freeit;
  540                 else
  541                         goto reflect;
  542 
  543         case ICMP_TSTAMP:
  544                 if (!V_icmpbmcastecho
  545                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
  546                         ICMPSTAT_INC(icps_bmcasttstamp);
  547                         break;
  548                 }
  549                 if (icmplen < ICMP_TSLEN) {
  550                         ICMPSTAT_INC(icps_badlen);
  551                         break;
  552                 }
  553                 icp->icmp_type = ICMP_TSTAMPREPLY;
  554                 icp->icmp_rtime = iptime();
  555                 icp->icmp_ttime = icp->icmp_rtime;      /* bogus, do later! */
  556                 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
  557                         goto freeit;
  558                 else
  559                         goto reflect;
  560 
  561         case ICMP_MASKREQ:
  562                 if (V_icmpmaskrepl == 0)
  563                         break;
  564                 /*
  565                  * We are not able to respond with all ones broadcast
  566                  * unless we receive it over a point-to-point interface.
  567                  */
  568                 if (icmplen < ICMP_MASKLEN)
  569                         break;
  570                 switch (ip->ip_dst.s_addr) {
  571 
  572                 case INADDR_BROADCAST:
  573                 case INADDR_ANY:
  574                         icmpdst.sin_addr = ip->ip_src;
  575                         break;
  576 
  577                 default:
  578                         icmpdst.sin_addr = ip->ip_dst;
  579                 }
  580                 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
  581                             (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
  582                 if (ia == NULL)
  583                         break;
  584                 if (ia->ia_ifp == NULL) {
  585                         ifa_free(&ia->ia_ifa);
  586                         break;
  587                 }
  588                 icp->icmp_type = ICMP_MASKREPLY;
  589                 if (V_icmpmaskfake == 0)
  590                         icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
  591                 else
  592                         icp->icmp_mask = V_icmpmaskfake;
  593                 if (ip->ip_src.s_addr == 0) {
  594                         if (ia->ia_ifp->if_flags & IFF_BROADCAST)
  595                             ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
  596                         else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
  597                             ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
  598                 }
  599                 ifa_free(&ia->ia_ifa);
  600 reflect:
  601                 ICMPSTAT_INC(icps_reflect);
  602                 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
  603                 icmp_reflect(m);
  604                 return;
  605 
  606         case ICMP_REDIRECT:
  607                 if (V_log_redirect) {
  608                         u_long src, dst, gw;
  609 
  610                         src = ntohl(ip->ip_src.s_addr);
  611                         dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
  612                         gw = ntohl(icp->icmp_gwaddr.s_addr);
  613                         printf("icmp redirect from %d.%d.%d.%d: "
  614                                "%d.%d.%d.%d => %d.%d.%d.%d\n",
  615                                (int)(src >> 24), (int)((src >> 16) & 0xff),
  616                                (int)((src >> 8) & 0xff), (int)(src & 0xff),
  617                                (int)(dst >> 24), (int)((dst >> 16) & 0xff),
  618                                (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
  619                                (int)(gw >> 24), (int)((gw >> 16) & 0xff),
  620                                (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
  621                 }
  622                 /*
  623                  * RFC1812 says we must ignore ICMP redirects if we
  624                  * are acting as router.
  625                  */
  626                 if (V_drop_redirect || V_ipforwarding)
  627                         break;
  628                 if (code > 3)
  629                         goto badcode;
  630                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
  631                     icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
  632                         ICMPSTAT_INC(icps_badlen);
  633                         break;
  634                 }
  635                 /*
  636                  * Short circuit routing redirects to force
  637                  * immediate change in the kernel's routing
  638                  * tables.  The message is also handed to anyone
  639                  * listening on a raw socket (e.g. the routing
  640                  * daemon for use in updating its tables).
  641                  */
  642                 icmpgw.sin_addr = ip->ip_src;
  643                 icmpdst.sin_addr = icp->icmp_gwaddr;
  644 #ifdef  ICMPPRINTFS
  645                 if (icmpprintfs) {
  646                         char buf[4 * sizeof "123"];
  647                         strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
  648 
  649                         printf("redirect dst %s to %s\n",
  650                                buf, inet_ntoa(icp->icmp_gwaddr));
  651                 }
  652 #endif
  653                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
  654                 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
  655                         in_rtredirect((struct sockaddr *)&icmpsrc,
  656                           (struct sockaddr *)&icmpdst,
  657                           (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
  658                           (struct sockaddr *)&icmpgw, fibnum);
  659                 }
  660                 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
  661 #ifdef IPSEC
  662                 key_sa_routechange((struct sockaddr *)&icmpsrc);
  663 #endif
  664                 break;
  665 
  666         /*
  667          * No kernel processing for the following;
  668          * just fall through to send to raw listener.
  669          */
  670         case ICMP_ECHOREPLY:
  671         case ICMP_ROUTERADVERT:
  672         case ICMP_ROUTERSOLICIT:
  673         case ICMP_TSTAMPREPLY:
  674         case ICMP_IREQREPLY:
  675         case ICMP_MASKREPLY:
  676         default:
  677                 break;
  678         }
  679 
  680 raw:
  681         rip_input(m, off);
  682         return;
  683 
  684 freeit:
  685         m_freem(m);
  686 }
  687 
  688 /*
  689  * Reflect the ip packet back to the source
  690  */
  691 static void
  692 icmp_reflect(struct mbuf *m)
  693 {
  694         struct ip *ip = mtod(m, struct ip *);
  695         struct ifaddr *ifa;
  696         struct ifnet *ifp;
  697         struct in_ifaddr *ia;
  698         struct in_addr t;
  699         struct mbuf *opts = 0;
  700         int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
  701 
  702         if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
  703             IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
  704             IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
  705                 m_freem(m);     /* Bad return address */
  706                 ICMPSTAT_INC(icps_badaddr);
  707                 goto done;      /* Ip_output() will check for broadcast */
  708         }
  709 
  710         t = ip->ip_dst;
  711         ip->ip_dst = ip->ip_src;
  712 
  713         /*
  714          * Source selection for ICMP replies:
  715          *
  716          * If the incoming packet was addressed directly to one of our
  717          * own addresses, use dst as the src for the reply.
  718          */
  719         IN_IFADDR_RLOCK();
  720         LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
  721                 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
  722                         t = IA_SIN(ia)->sin_addr;
  723                         IN_IFADDR_RUNLOCK();
  724                         goto match;
  725                 }
  726         }
  727         IN_IFADDR_RUNLOCK();
  728 
  729         /*
  730          * If the incoming packet was addressed to one of our broadcast
  731          * addresses, use the first non-broadcast address which corresponds
  732          * to the incoming interface.
  733          */
  734         ifp = m->m_pkthdr.rcvif;
  735         if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
  736                 IF_ADDR_RLOCK(ifp);
  737                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  738                         if (ifa->ifa_addr->sa_family != AF_INET)
  739                                 continue;
  740                         ia = ifatoia(ifa);
  741                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
  742                             t.s_addr) {
  743                                 t = IA_SIN(ia)->sin_addr;
  744                                 IF_ADDR_RUNLOCK(ifp);
  745                                 goto match;
  746                         }
  747                 }
  748                 IF_ADDR_RUNLOCK(ifp);
  749         }
  750         /*
  751          * If the packet was transiting through us, use the address of
  752          * the interface the packet came through in.  If that interface
  753          * doesn't have a suitable IP address, the normal selection
  754          * criteria apply.
  755          */
  756         if (V_icmp_rfi && ifp != NULL) {
  757                 IF_ADDR_RLOCK(ifp);
  758                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  759                         if (ifa->ifa_addr->sa_family != AF_INET)
  760                                 continue;
  761                         ia = ifatoia(ifa);
  762                         t = IA_SIN(ia)->sin_addr;
  763                         IF_ADDR_RUNLOCK(ifp);
  764                         goto match;
  765                 }
  766                 IF_ADDR_RUNLOCK(ifp);
  767         }
  768         /*
  769          * If the incoming packet was not addressed directly to us, use
  770          * designated interface for icmp replies specified by sysctl
  771          * net.inet.icmp.reply_src (default not set). Otherwise continue
  772          * with normal source selection.
  773          */
  774         if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
  775                 IF_ADDR_RLOCK(ifp);
  776                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  777                         if (ifa->ifa_addr->sa_family != AF_INET)
  778                                 continue;
  779                         ia = ifatoia(ifa);
  780                         t = IA_SIN(ia)->sin_addr;
  781                         IF_ADDR_RUNLOCK(ifp);
  782                         goto match;
  783                 }
  784                 IF_ADDR_RUNLOCK(ifp);
  785         }
  786         /*
  787          * If the packet was transiting through us, use the address of
  788          * the interface that is the closest to the packet source.
  789          * When we don't have a route back to the packet source, stop here
  790          * and drop the packet.
  791          */
  792         ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
  793         if (ia == NULL) {
  794                 m_freem(m);
  795                 ICMPSTAT_INC(icps_noroute);
  796                 goto done;
  797         }
  798         t = IA_SIN(ia)->sin_addr;
  799         ifa_free(&ia->ia_ifa);
  800 match:
  801 #ifdef MAC
  802         mac_netinet_icmp_replyinplace(m);
  803 #endif
  804         ip->ip_src = t;
  805         ip->ip_ttl = V_ip_defttl;
  806 
  807         if (optlen > 0) {
  808                 register u_char *cp;
  809                 int opt, cnt;
  810                 u_int len;
  811 
  812                 /*
  813                  * Retrieve any source routing from the incoming packet;
  814                  * add on any record-route or timestamp options.
  815                  */
  816                 cp = (u_char *) (ip + 1);
  817                 if ((opts = ip_srcroute(m)) == 0 &&
  818                     (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
  819                         opts->m_len = sizeof(struct in_addr);
  820                         mtod(opts, struct in_addr *)->s_addr = 0;
  821                 }
  822                 if (opts) {
  823 #ifdef ICMPPRINTFS
  824                     if (icmpprintfs)
  825                             printf("icmp_reflect optlen %d rt %d => ",
  826                                 optlen, opts->m_len);
  827 #endif
  828                     for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
  829                             opt = cp[IPOPT_OPTVAL];
  830                             if (opt == IPOPT_EOL)
  831                                     break;
  832                             if (opt == IPOPT_NOP)
  833                                     len = 1;
  834                             else {
  835                                     if (cnt < IPOPT_OLEN + sizeof(*cp))
  836                                             break;
  837                                     len = cp[IPOPT_OLEN];
  838                                     if (len < IPOPT_OLEN + sizeof(*cp) ||
  839                                         len > cnt)
  840                                             break;
  841                             }
  842                             /*
  843                              * Should check for overflow, but it "can't happen"
  844                              */
  845                             if (opt == IPOPT_RR || opt == IPOPT_TS ||
  846                                 opt == IPOPT_SECURITY) {
  847                                     bcopy((caddr_t)cp,
  848                                         mtod(opts, caddr_t) + opts->m_len, len);
  849                                     opts->m_len += len;
  850                             }
  851                     }
  852                     /* Terminate & pad, if necessary */
  853                     cnt = opts->m_len % 4;
  854                     if (cnt) {
  855                             for (; cnt < 4; cnt++) {
  856                                     *(mtod(opts, caddr_t) + opts->m_len) =
  857                                         IPOPT_EOL;
  858                                     opts->m_len++;
  859                             }
  860                     }
  861 #ifdef ICMPPRINTFS
  862                     if (icmpprintfs)
  863                             printf("%d\n", opts->m_len);
  864 #endif
  865                 }
  866                 ip_stripoptions(m);
  867         }
  868         m_tag_delete_nonpersistent(m);
  869         m->m_flags &= ~(M_BCAST|M_MCAST);
  870         icmp_send(m, opts);
  871 done:
  872         if (opts)
  873                 (void)m_free(opts);
  874 }
  875 
  876 /*
  877  * Send an icmp packet back to the ip level,
  878  * after supplying a checksum.
  879  */
  880 static void
  881 icmp_send(struct mbuf *m, struct mbuf *opts)
  882 {
  883         register struct ip *ip = mtod(m, struct ip *);
  884         register int hlen;
  885         register struct icmp *icp;
  886 
  887         hlen = ip->ip_hl << 2;
  888         m->m_data += hlen;
  889         m->m_len -= hlen;
  890         icp = mtod(m, struct icmp *);
  891         icp->icmp_cksum = 0;
  892         icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
  893         m->m_data -= hlen;
  894         m->m_len += hlen;
  895         m->m_pkthdr.rcvif = (struct ifnet *)0;
  896 #ifdef ICMPPRINTFS
  897         if (icmpprintfs) {
  898                 char buf[4 * sizeof "123"];
  899                 strcpy(buf, inet_ntoa(ip->ip_dst));
  900                 printf("icmp_send dst %s src %s\n",
  901                        buf, inet_ntoa(ip->ip_src));
  902         }
  903 #endif
  904         (void) ip_output(m, opts, NULL, 0, NULL, NULL);
  905 }
  906 
  907 /*
  908  * Return milliseconds since 00:00 GMT in network format.
  909  */
  910 uint32_t
  911 iptime(void)
  912 {
  913         struct timeval atv;
  914         u_long t;
  915 
  916         getmicrotime(&atv);
  917         t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
  918         return (htonl(t));
  919 }
  920 
  921 /*
  922  * Return the next larger or smaller MTU plateau (table from RFC 1191)
  923  * given current value MTU.  If DIR is less than zero, a larger plateau
  924  * is returned; otherwise, a smaller value is returned.
  925  */
  926 int
  927 ip_next_mtu(int mtu, int dir)
  928 {
  929         static int mtutab[] = {
  930                 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
  931                 296, 68, 0
  932         };
  933         int i, size;
  934 
  935         size = (sizeof mtutab) / (sizeof mtutab[0]);
  936         if (dir >= 0) {
  937                 for (i = 0; i < size; i++)
  938                         if (mtu > mtutab[i])
  939                                 return mtutab[i];
  940         } else {
  941                 for (i = size - 1; i >= 0; i--)
  942                         if (mtu < mtutab[i])
  943                                 return mtutab[i];
  944                 if (mtu == mtutab[0])
  945                         return mtutab[0];
  946         }
  947         return 0;
  948 }
  949 #endif /* INET */
  950 
  951 
  952 /*
  953  * badport_bandlim() - check for ICMP bandwidth limit
  954  *
  955  *      Return 0 if it is ok to send an ICMP error response, -1 if we have
  956  *      hit our bandwidth limit and it is not ok.
  957  *
  958  *      If icmplim is <= 0, the feature is disabled and 0 is returned.
  959  *
  960  *      For now we separate the TCP and UDP subsystems w/ different 'which'
  961  *      values.  We may eventually remove this separation (and simplify the
  962  *      code further).
  963  *
  964  *      Note that the printing of the error message is delayed so we can
  965  *      properly print the icmp error rate that the system was trying to do
  966  *      (i.e. 22000/100 pps, etc...).  This can cause long delays in printing
  967  *      the 'final' error, but it doesn't make sense to solve the printing
  968  *      delay with more complex code.
  969  */
  970 
  971 int
  972 badport_bandlim(int which)
  973 {
  974 
  975 #define N(a)    (sizeof (a) / sizeof (a[0]))
  976         static struct rate {
  977                 const char      *type;
  978                 struct timeval  lasttime;
  979                 int             curpps;
  980         } rates[BANDLIM_MAX+1] = {
  981                 { "icmp unreach response" },
  982                 { "icmp ping response" },
  983                 { "icmp tstamp response" },
  984                 { "closed port RST response" },
  985                 { "open port RST response" },
  986                 { "icmp6 unreach response" },
  987                 { "sctp ootb response" }
  988         };
  989 
  990         /*
  991          * Return ok status if feature disabled or argument out of range.
  992          */
  993         if (V_icmplim > 0 && (u_int) which < N(rates)) {
  994                 struct rate *r = &rates[which];
  995                 int opps = r->curpps;
  996 
  997                 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
  998                         return -1;      /* discard packet */
  999                 /*
 1000                  * If we've dropped below the threshold after having
 1001                  * rate-limited traffic print the message.  This preserves
 1002                  * the previous behaviour at the expense of added complexity.
 1003                  */
 1004                 if (V_icmplim_output && opps > V_icmplim)
 1005                         log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
 1006                                 r->type, opps, V_icmplim);
 1007         }
 1008         return 0;                       /* okay to send packet */
 1009 #undef N
 1010 }

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