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("$FreeBSD$");
   34 
   35 #include "opt_ipsec.h"
   36 
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/mbuf.h>
   40 #include <sys/protosw.h>
   41 #include <sys/socket.h>
   42 #include <sys/time.h>
   43 #include <sys/kernel.h>
   44 #include <sys/sysctl.h>
   45 #include <sys/syslog.h>
   46 
   47 #include <net/if.h>
   48 #include <net/if_types.h>
   49 #include <net/route.h>
   50 #include <net/vnet.h>
   51 
   52 #include <netinet/in.h>
   53 #include <netinet/in_pcb.h>
   54 #include <netinet/in_systm.h>
   55 #include <netinet/in_var.h>
   56 #include <netinet/ip.h>
   57 #include <netinet/ip_icmp.h>
   58 #include <netinet/ip_var.h>
   59 #include <netinet/ip_options.h>
   60 #include <netinet/tcp.h>
   61 #include <netinet/tcp_var.h>
   62 #include <netinet/tcpip.h>
   63 #include <netinet/icmp_var.h>
   64 
   65 #ifdef IPSEC
   66 #include <netipsec/ipsec.h>
   67 #include <netipsec/key.h>
   68 #endif
   69 
   70 #include <machine/in_cksum.h>
   71 
   72 #include <security/mac/mac_framework.h>
   73 
   74 /*
   75  * ICMP routines: error generation, receive packet processing, and
   76  * routines to turnaround packets back to the originator, and
   77  * host table maintenance routines.
   78  */
   79 VNET_DEFINE(struct icmpstat, icmpstat);
   80 SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
   81         &VNET_NAME(icmpstat), icmpstat, "");
   82 
   83 static VNET_DEFINE(int, icmpmaskrepl) = 0;
   84 #define V_icmpmaskrepl                  VNET(icmpmaskrepl)
   85 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
   86         &VNET_NAME(icmpmaskrepl), 0,
   87         "Reply to ICMP Address Mask Request packets.");
   88 
   89 static VNET_DEFINE(u_int, icmpmaskfake) = 0;
   90 #define V_icmpmaskfake                  VNET(icmpmaskfake)
   91 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
   92         &VNET_NAME(icmpmaskfake), 0,
   93         "Fake reply to ICMP Address Mask Request packets.");
   94 
   95 VNET_DEFINE(int, drop_redirect) = 0;
   96 
   97 static VNET_DEFINE(int, log_redirect) = 0;
   98 #define V_log_redirect                  VNET(log_redirect)
   99 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
  100         &VNET_NAME(log_redirect), 0,
  101         "Log ICMP redirects to the console");
  102 
  103 static VNET_DEFINE(int, icmplim) = 200;
  104 #define V_icmplim                       VNET(icmplim)
  105 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
  106         &VNET_NAME(icmplim), 0,
  107         "Maximum number of ICMP responses per second");
  108 
  109 static VNET_DEFINE(int, icmplim_output) = 1;
  110 #define V_icmplim_output                VNET(icmplim_output)
  111 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
  112         &VNET_NAME(icmplim_output), 0,
  113         "Enable rate limiting of ICMP responses");
  114 
  115 static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
  116 #define V_reply_src                     VNET(reply_src)
  117 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
  118         &VNET_NAME(reply_src), IFNAMSIZ,
  119         "icmp reply source for non-local packets.");
  120 
  121 static VNET_DEFINE(int, icmp_rfi) = 0;
  122 #define V_icmp_rfi                      VNET(icmp_rfi)
  123 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
  124         &VNET_NAME(icmp_rfi), 0,
  125         "ICMP reply from incoming interface for non-local packets");
  126 
  127 static VNET_DEFINE(int, icmp_quotelen) = 8;
  128 #define V_icmp_quotelen                 VNET(icmp_quotelen)
  129 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
  130         &VNET_NAME(icmp_quotelen), 0,
  131         "Number of bytes from original packet to quote in ICMP reply");
  132 
  133 /*
  134  * ICMP broadcast echo sysctl
  135  */
  136 static VNET_DEFINE(int, icmpbmcastecho) = 0;
  137 #define V_icmpbmcastecho                VNET(icmpbmcastecho)
  138 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
  139         &VNET_NAME(icmpbmcastecho), 0,
  140         "");
  141 
  142 
  143 #ifdef ICMPPRINTFS
  144 int     icmpprintfs = 0;
  145 #endif
  146 
  147 static void     icmp_reflect(struct mbuf *);
  148 static void     icmp_send(struct mbuf *, struct mbuf *);
  149 
  150 extern  struct protosw inetsw[];
  151 
  152 static int
  153 sysctl_net_icmp_drop_redir(SYSCTL_HANDLER_ARGS)
  154 {
  155         int error, new;
  156         int i;
  157         struct radix_node_head *rnh;
  158 
  159         new = V_drop_redirect;
  160         error = sysctl_handle_int(oidp, &new, 0, req);
  161         if (error == 0 && req->newptr) {
  162                 new = (new != 0) ? 1 : 0;
  163 
  164                 if (new == V_drop_redirect)
  165                         return (0);
  166 
  167                 for (i = 0; i < rt_numfibs; i++) {
  168                         if ((rnh = rt_tables_get_rnh(i, AF_INET)) == NULL)
  169                                 continue;
  170                         RADIX_NODE_HEAD_LOCK(rnh);
  171                         in_setmatchfunc(rnh, new);
  172                         RADIX_NODE_HEAD_UNLOCK(rnh);
  173                 }
  174                 
  175                 V_drop_redirect = new;
  176         }
  177 
  178         return (error);
  179 }
  180 
  181 SYSCTL_VNET_PROC(_net_inet_icmp, OID_AUTO, drop_redirect,
  182     CTLTYPE_INT|CTLFLAG_RW, 0, 0,
  183     sysctl_net_icmp_drop_redir, "I", "Ignore ICMP redirects");
  184 
  185 /*
  186  * Kernel module interface for updating icmpstat.  The argument is an index
  187  * into icmpstat treated as an array of u_long.  While this encodes the
  188  * general layout of icmpstat into the caller, it doesn't encode its
  189  * location, so that future changes to add, for example, per-CPU stats
  190  * support won't cause binary compatibility problems for kernel modules.
  191  */
  192 void
  193 kmod_icmpstat_inc(int statnum)
  194 {
  195 
  196         (*((u_long *)&V_icmpstat + statnum))++;
  197 }
  198 
  199 /*
  200  * Generate an error packet of type error
  201  * in response to bad packet ip.
  202  */
  203 void
  204 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
  205 {
  206         register struct ip *oip = mtod(n, struct ip *), *nip;
  207         register unsigned oiphlen = oip->ip_hl << 2;
  208         register struct icmp *icp;
  209         register struct mbuf *m;
  210         unsigned icmplen, icmpelen, nlen;
  211 
  212         KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
  213 #ifdef ICMPPRINTFS
  214         if (icmpprintfs)
  215                 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
  216 #endif
  217         if (type != ICMP_REDIRECT)
  218                 ICMPSTAT_INC(icps_error);
  219         /*
  220          * Don't send error:
  221          *  if the original packet was encrypted.
  222          *  if not the first fragment of message.
  223          *  in response to a multicast or broadcast packet.
  224          *  if the old packet protocol was an ICMP error message.
  225          */
  226         if (n->m_flags & M_DECRYPTED)
  227                 goto freeit;
  228         if (oip->ip_off & ~(IP_MF|IP_DF))
  229                 goto freeit;
  230         if (n->m_flags & (M_BCAST|M_MCAST))
  231                 goto freeit;
  232         if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
  233           n->m_len >= oiphlen + ICMP_MINLEN &&
  234           !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
  235                 ICMPSTAT_INC(icps_oldicmp);
  236                 goto freeit;
  237         }
  238         /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
  239         if (oiphlen + 8 > n->m_len)
  240                 goto freeit;
  241         /*
  242          * Calculate length to quote from original packet and
  243          * prevent the ICMP mbuf from overflowing.
  244          * Unfortunatly this is non-trivial since ip_forward()
  245          * sends us truncated packets.
  246          */
  247         nlen = m_length(n, NULL);
  248         if (oip->ip_p == IPPROTO_TCP) {
  249                 struct tcphdr *th;
  250                 int tcphlen;
  251 
  252                 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
  253                     n->m_next == NULL)
  254                         goto stdreply;
  255                 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
  256                     ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
  257                         goto freeit;
  258                 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
  259                 tcphlen = th->th_off << 2;
  260                 if (tcphlen < sizeof(struct tcphdr))
  261                         goto freeit;
  262                 if (oip->ip_len < oiphlen + tcphlen)
  263                         goto freeit;
  264                 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
  265                         goto stdreply;
  266                 if (n->m_len < oiphlen + tcphlen && 
  267                     ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
  268                         goto freeit;
  269                 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen));
  270         } else
  271 stdreply:       icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen));
  272 
  273         icmplen = min(oiphlen + icmpelen, nlen);
  274         if (icmplen < sizeof(struct ip))
  275                 goto freeit;
  276 
  277         if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
  278                 m = m_gethdr(M_DONTWAIT, MT_DATA);
  279         else
  280                 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
  281         if (m == NULL)
  282                 goto freeit;
  283 #ifdef MAC
  284         mac_netinet_icmp_reply(n, m);
  285 #endif
  286         icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
  287         m_align(m, ICMP_MINLEN + icmplen);
  288         m->m_len = ICMP_MINLEN + icmplen;
  289 
  290         /* XXX MRT  make the outgoing packet use the same FIB
  291          * that was associated with the incoming packet
  292          */
  293         M_SETFIB(m, M_GETFIB(n));
  294         icp = mtod(m, struct icmp *);
  295         ICMPSTAT_INC(icps_outhist[type]);
  296         icp->icmp_type = type;
  297         if (type == ICMP_REDIRECT)
  298                 icp->icmp_gwaddr.s_addr = dest;
  299         else {
  300                 icp->icmp_void = 0;
  301                 /*
  302                  * The following assignments assume an overlay with the
  303                  * just zeroed icmp_void field.
  304                  */
  305                 if (type == ICMP_PARAMPROB) {
  306                         icp->icmp_pptr = code;
  307                         code = 0;
  308                 } else if (type == ICMP_UNREACH &&
  309                         code == ICMP_UNREACH_NEEDFRAG && mtu) {
  310                         icp->icmp_nextmtu = htons(mtu);
  311                 }
  312         }
  313         icp->icmp_code = code;
  314 
  315         /*
  316          * Copy the quotation into ICMP message and
  317          * convert quoted IP header back to network representation.
  318          */
  319         m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
  320         nip = &icp->icmp_ip;
  321         nip->ip_len = htons(nip->ip_len);
  322         nip->ip_off = htons(nip->ip_off);
  323 
  324         /*
  325          * Set up ICMP message mbuf and copy old IP header (without options
  326          * in front of ICMP message.
  327          * If the original mbuf was meant to bypass the firewall, the error
  328          * reply should bypass as well.
  329          */
  330         m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
  331         m->m_data -= sizeof(struct ip);
  332         m->m_len += sizeof(struct ip);
  333         m->m_pkthdr.len = m->m_len;
  334         m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
  335         nip = mtod(m, struct ip *);
  336         bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
  337         nip->ip_len = m->m_len;
  338         nip->ip_v = IPVERSION;
  339         nip->ip_hl = 5;
  340         nip->ip_p = IPPROTO_ICMP;
  341         nip->ip_tos = 0;
  342         nip->ip_off = 0;
  343         icmp_reflect(m);
  344 
  345 freeit:
  346         m_freem(n);
  347 }
  348 
  349 /*
  350  * Process a received ICMP message.
  351  */
  352 void
  353 icmp_input(struct mbuf *m, int off)
  354 {
  355         struct icmp *icp;
  356         struct in_ifaddr *ia;
  357         struct ip *ip = mtod(m, struct ip *);
  358         struct sockaddr_in icmpsrc, icmpdst, icmpgw;
  359         int hlen = off;
  360         int icmplen = ip->ip_len;
  361         int i, code;
  362         void (*ctlfunc)(int, struct sockaddr *, void *);
  363         int fibnum;
  364 
  365         /*
  366          * Locate icmp structure in mbuf, and check
  367          * that not corrupted and of at least minimum length.
  368          */
  369 #ifdef ICMPPRINTFS
  370         if (icmpprintfs) {
  371                 char buf[4 * sizeof "123"];
  372                 strcpy(buf, inet_ntoa(ip->ip_src));
  373                 printf("icmp_input from %s to %s, len %d\n",
  374                        buf, inet_ntoa(ip->ip_dst), icmplen);
  375         }
  376 #endif
  377         if (icmplen < ICMP_MINLEN) {
  378                 ICMPSTAT_INC(icps_tooshort);
  379                 goto freeit;
  380         }
  381         i = hlen + min(icmplen, ICMP_ADVLENMIN);
  382         if (m->m_len < i && (m = m_pullup(m, i)) == NULL)  {
  383                 ICMPSTAT_INC(icps_tooshort);
  384                 return;
  385         }
  386         ip = mtod(m, struct ip *);
  387         m->m_len -= hlen;
  388         m->m_data += hlen;
  389         icp = mtod(m, struct icmp *);
  390         if (in_cksum(m, icmplen)) {
  391                 ICMPSTAT_INC(icps_checksum);
  392                 goto freeit;
  393         }
  394         m->m_len += hlen;
  395         m->m_data -= hlen;
  396 
  397         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
  398                 /*
  399                  * Deliver very specific ICMP type only.
  400                  */
  401                 switch (icp->icmp_type) {
  402                 case ICMP_UNREACH:
  403                 case ICMP_TIMXCEED:
  404                         break;
  405                 default:
  406                         goto freeit;
  407                 }
  408         }
  409 
  410 #ifdef ICMPPRINTFS
  411         if (icmpprintfs)
  412                 printf("icmp_input, type %d code %d\n", icp->icmp_type,
  413                     icp->icmp_code);
  414 #endif
  415 
  416         /*
  417          * Message type specific processing.
  418          */
  419         if (icp->icmp_type > ICMP_MAXTYPE)
  420                 goto raw;
  421 
  422         /* Initialize */
  423         bzero(&icmpsrc, sizeof(icmpsrc));
  424         icmpsrc.sin_len = sizeof(struct sockaddr_in);
  425         icmpsrc.sin_family = AF_INET;
  426         bzero(&icmpdst, sizeof(icmpdst));
  427         icmpdst.sin_len = sizeof(struct sockaddr_in);
  428         icmpdst.sin_family = AF_INET;
  429         bzero(&icmpgw, sizeof(icmpgw));
  430         icmpgw.sin_len = sizeof(struct sockaddr_in);
  431         icmpgw.sin_family = AF_INET;
  432 
  433         ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
  434         code = icp->icmp_code;
  435         switch (icp->icmp_type) {
  436 
  437         case ICMP_UNREACH:
  438                 switch (code) {
  439                         case ICMP_UNREACH_NET:
  440                         case ICMP_UNREACH_HOST:
  441                         case ICMP_UNREACH_SRCFAIL:
  442                         case ICMP_UNREACH_NET_UNKNOWN:
  443                         case ICMP_UNREACH_HOST_UNKNOWN:
  444                         case ICMP_UNREACH_ISOLATED:
  445                         case ICMP_UNREACH_TOSNET:
  446                         case ICMP_UNREACH_TOSHOST:
  447                         case ICMP_UNREACH_HOST_PRECEDENCE:
  448                         case ICMP_UNREACH_PRECEDENCE_CUTOFF:
  449                                 code = PRC_UNREACH_NET;
  450                                 break;
  451 
  452                         case ICMP_UNREACH_NEEDFRAG:
  453                                 code = PRC_MSGSIZE;
  454                                 break;
  455 
  456                         /*
  457                          * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
  458                          * Treat subcodes 2,3 as immediate RST
  459                          */
  460                         case ICMP_UNREACH_PROTOCOL:
  461                         case ICMP_UNREACH_PORT:
  462                                 code = PRC_UNREACH_PORT;
  463                                 break;
  464 
  465                         case ICMP_UNREACH_NET_PROHIB:
  466                         case ICMP_UNREACH_HOST_PROHIB:
  467                         case ICMP_UNREACH_FILTER_PROHIB:
  468                                 code = PRC_UNREACH_ADMIN_PROHIB;
  469                                 break;
  470 
  471                         default:
  472                                 goto badcode;
  473                 }
  474                 goto deliver;
  475 
  476         case ICMP_TIMXCEED:
  477                 if (code > 1)
  478                         goto badcode;
  479                 code += PRC_TIMXCEED_INTRANS;
  480                 goto deliver;
  481 
  482         case ICMP_PARAMPROB:
  483                 if (code > 1)
  484                         goto badcode;
  485                 code = PRC_PARAMPROB;
  486                 goto deliver;
  487 
  488         case ICMP_SOURCEQUENCH:
  489                 if (code)
  490                         goto badcode;
  491                 code = PRC_QUENCH;
  492         deliver:
  493                 /*
  494                  * Problem with datagram; advise higher level routines.
  495                  */
  496                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
  497                     icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
  498                         ICMPSTAT_INC(icps_badlen);
  499                         goto freeit;
  500                 }
  501                 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
  502                 /* Discard ICMP's in response to multicast packets */
  503                 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
  504                         goto badcode;
  505 #ifdef ICMPPRINTFS
  506                 if (icmpprintfs)
  507                         printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
  508 #endif
  509                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
  510                 /*
  511                  * XXX if the packet contains [IPv4 AH TCP], we can't make a
  512                  * notification to TCP layer.
  513                  */
  514                 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
  515                 if (ctlfunc)
  516                         (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
  517                                    (void *)&icp->icmp_ip);
  518                 break;
  519 
  520         badcode:
  521                 ICMPSTAT_INC(icps_badcode);
  522                 break;
  523 
  524         case ICMP_ECHO:
  525                 if (!V_icmpbmcastecho
  526                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
  527                         ICMPSTAT_INC(icps_bmcastecho);
  528                         break;
  529                 }
  530                 icp->icmp_type = ICMP_ECHOREPLY;
  531                 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
  532                         goto freeit;
  533                 else
  534                         goto reflect;
  535 
  536         case ICMP_TSTAMP:
  537                 if (!V_icmpbmcastecho
  538                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
  539                         ICMPSTAT_INC(icps_bmcasttstamp);
  540                         break;
  541                 }
  542                 if (icmplen < ICMP_TSLEN) {
  543                         ICMPSTAT_INC(icps_badlen);
  544                         break;
  545                 }
  546                 icp->icmp_type = ICMP_TSTAMPREPLY;
  547                 icp->icmp_rtime = iptime();
  548                 icp->icmp_ttime = icp->icmp_rtime;      /* bogus, do later! */
  549                 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
  550                         goto freeit;
  551                 else
  552                         goto reflect;
  553 
  554         case ICMP_MASKREQ:
  555                 if (V_icmpmaskrepl == 0)
  556                         break;
  557                 /*
  558                  * We are not able to respond with all ones broadcast
  559                  * unless we receive it over a point-to-point interface.
  560                  */
  561                 if (icmplen < ICMP_MASKLEN)
  562                         break;
  563                 switch (ip->ip_dst.s_addr) {
  564 
  565                 case INADDR_BROADCAST:
  566                 case INADDR_ANY:
  567                         icmpdst.sin_addr = ip->ip_src;
  568                         break;
  569 
  570                 default:
  571                         icmpdst.sin_addr = ip->ip_dst;
  572                 }
  573                 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
  574                             (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
  575                 if (ia == NULL)
  576                         break;
  577                 if (ia->ia_ifp == NULL) {
  578                         ifa_free(&ia->ia_ifa);
  579                         break;
  580                 }
  581                 icp->icmp_type = ICMP_MASKREPLY;
  582                 if (V_icmpmaskfake == 0)
  583                         icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
  584                 else
  585                         icp->icmp_mask = V_icmpmaskfake;
  586                 if (ip->ip_src.s_addr == 0) {
  587                         if (ia->ia_ifp->if_flags & IFF_BROADCAST)
  588                             ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
  589                         else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
  590                             ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
  591                 }
  592                 ifa_free(&ia->ia_ifa);
  593 reflect:
  594                 ip->ip_len += hlen;     /* since ip_input deducts this */
  595                 ICMPSTAT_INC(icps_reflect);
  596                 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
  597                 icmp_reflect(m);
  598                 return;
  599 
  600         case ICMP_REDIRECT:
  601                 if (V_log_redirect) {
  602                         u_long src, dst, gw;
  603 
  604                         src = ntohl(ip->ip_src.s_addr);
  605                         dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
  606                         gw = ntohl(icp->icmp_gwaddr.s_addr);
  607                         printf("icmp redirect from %d.%d.%d.%d: "
  608                                "%d.%d.%d.%d => %d.%d.%d.%d\n",
  609                                (int)(src >> 24), (int)((src >> 16) & 0xff),
  610                                (int)((src >> 8) & 0xff), (int)(src & 0xff),
  611                                (int)(dst >> 24), (int)((dst >> 16) & 0xff),
  612                                (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
  613                                (int)(gw >> 24), (int)((gw >> 16) & 0xff),
  614                                (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
  615                 }
  616                 /*
  617                  * RFC1812 says we must ignore ICMP redirects if we
  618                  * are acting as router.
  619                  */
  620                 if (V_drop_redirect || V_ipforwarding)
  621                         break;
  622                 if (code > 3)
  623                         goto badcode;
  624                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
  625                     icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
  626                         ICMPSTAT_INC(icps_badlen);
  627                         break;
  628                 }
  629                 /*
  630                  * Short circuit routing redirects to force
  631                  * immediate change in the kernel's routing
  632                  * tables.  The message is also handed to anyone
  633                  * listening on a raw socket (e.g. the routing
  634                  * daemon for use in updating its tables).
  635                  */
  636                 icmpgw.sin_addr = ip->ip_src;
  637                 icmpdst.sin_addr = icp->icmp_gwaddr;
  638 #ifdef  ICMPPRINTFS
  639                 if (icmpprintfs) {
  640                         char buf[4 * sizeof "123"];
  641                         strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
  642 
  643                         printf("redirect dst %s to %s\n",
  644                                buf, inet_ntoa(icp->icmp_gwaddr));
  645                 }
  646 #endif
  647                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
  648                 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
  649                         in_rtredirect((struct sockaddr *)&icmpsrc,
  650                           (struct sockaddr *)&icmpdst,
  651                           (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
  652                           (struct sockaddr *)&icmpgw, fibnum);
  653                 }
  654                 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
  655 #ifdef IPSEC
  656                 key_sa_routechange((struct sockaddr *)&icmpsrc);
  657 #endif
  658                 break;
  659 
  660         /*
  661          * No kernel processing for the following;
  662          * just fall through to send to raw listener.
  663          */
  664         case ICMP_ECHOREPLY:
  665         case ICMP_ROUTERADVERT:
  666         case ICMP_ROUTERSOLICIT:
  667         case ICMP_TSTAMPREPLY:
  668         case ICMP_IREQREPLY:
  669         case ICMP_MASKREPLY:
  670         default:
  671                 break;
  672         }
  673 
  674 raw:
  675         rip_input(m, off);
  676         return;
  677 
  678 freeit:
  679         m_freem(m);
  680 }
  681 
  682 /*
  683  * Reflect the ip packet back to the source
  684  */
  685 static void
  686 icmp_reflect(struct mbuf *m)
  687 {
  688         struct ip *ip = mtod(m, struct ip *);
  689         struct ifaddr *ifa;
  690         struct ifnet *ifp;
  691         struct in_ifaddr *ia;
  692         struct in_addr t;
  693         struct mbuf *opts = 0;
  694         int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
  695 
  696         if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
  697             IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
  698             IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
  699                 m_freem(m);     /* Bad return address */
  700                 ICMPSTAT_INC(icps_badaddr);
  701                 goto done;      /* Ip_output() will check for broadcast */
  702         }
  703 
  704         t = ip->ip_dst;
  705         ip->ip_dst = ip->ip_src;
  706 
  707         /*
  708          * Source selection for ICMP replies:
  709          *
  710          * If the incoming packet was addressed directly to one of our
  711          * own addresses, use dst as the src for the reply.
  712          */
  713         IN_IFADDR_RLOCK();
  714         LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
  715                 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
  716                         t = IA_SIN(ia)->sin_addr;
  717                         IN_IFADDR_RUNLOCK();
  718                         goto match;
  719                 }
  720         }
  721         IN_IFADDR_RUNLOCK();
  722 
  723         /*
  724          * If the incoming packet was addressed to one of our broadcast
  725          * addresses, use the first non-broadcast address which corresponds
  726          * to the incoming interface.
  727          */
  728         ifp = m->m_pkthdr.rcvif;
  729         if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
  730                 IF_ADDR_RLOCK(ifp);
  731                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  732                         if (ifa->ifa_addr->sa_family != AF_INET)
  733                                 continue;
  734                         ia = ifatoia(ifa);
  735                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
  736                             t.s_addr) {
  737                                 t = IA_SIN(ia)->sin_addr;
  738                                 IF_ADDR_RUNLOCK(ifp);
  739                                 goto match;
  740                         }
  741                 }
  742                 IF_ADDR_RUNLOCK(ifp);
  743         }
  744         /*
  745          * If the packet was transiting through us, use the address of
  746          * the interface the packet came through in.  If that interface
  747          * doesn't have a suitable IP address, the normal selection
  748          * criteria apply.
  749          */
  750         if (V_icmp_rfi && ifp != NULL) {
  751                 IF_ADDR_RLOCK(ifp);
  752                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  753                         if (ifa->ifa_addr->sa_family != AF_INET)
  754                                 continue;
  755                         ia = ifatoia(ifa);
  756                         t = IA_SIN(ia)->sin_addr;
  757                         IF_ADDR_RUNLOCK(ifp);
  758                         goto match;
  759                 }
  760                 IF_ADDR_RUNLOCK(ifp);
  761         }
  762         /*
  763          * If the incoming packet was not addressed directly to us, use
  764          * designated interface for icmp replies specified by sysctl
  765          * net.inet.icmp.reply_src (default not set). Otherwise continue
  766          * with normal source selection.
  767          */
  768         if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
  769                 IF_ADDR_RLOCK(ifp);
  770                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  771                         if (ifa->ifa_addr->sa_family != AF_INET)
  772                                 continue;
  773                         ia = ifatoia(ifa);
  774                         t = IA_SIN(ia)->sin_addr;
  775                         IF_ADDR_RUNLOCK(ifp);
  776                         goto match;
  777                 }
  778                 IF_ADDR_RUNLOCK(ifp);
  779         }
  780         /*
  781          * If the packet was transiting through us, use the address of
  782          * the interface that is the closest to the packet source.
  783          * When we don't have a route back to the packet source, stop here
  784          * and drop the packet.
  785          */
  786         ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
  787         if (ia == NULL) {
  788                 m_freem(m);
  789                 ICMPSTAT_INC(icps_noroute);
  790                 goto done;
  791         }
  792         t = IA_SIN(ia)->sin_addr;
  793         ifa_free(&ia->ia_ifa);
  794 match:
  795 #ifdef MAC
  796         mac_netinet_icmp_replyinplace(m);
  797 #endif
  798         ip->ip_src = t;
  799         ip->ip_ttl = V_ip_defttl;
  800 
  801         if (optlen > 0) {
  802                 register u_char *cp;
  803                 int opt, cnt;
  804                 u_int len;
  805 
  806                 /*
  807                  * Retrieve any source routing from the incoming packet;
  808                  * add on any record-route or timestamp options.
  809                  */
  810                 cp = (u_char *) (ip + 1);
  811                 if ((opts = ip_srcroute(m)) == 0 &&
  812                     (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
  813                         opts->m_len = sizeof(struct in_addr);
  814                         mtod(opts, struct in_addr *)->s_addr = 0;
  815                 }
  816                 if (opts) {
  817 #ifdef ICMPPRINTFS
  818                     if (icmpprintfs)
  819                             printf("icmp_reflect optlen %d rt %d => ",
  820                                 optlen, opts->m_len);
  821 #endif
  822                     for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
  823                             opt = cp[IPOPT_OPTVAL];
  824                             if (opt == IPOPT_EOL)
  825                                     break;
  826                             if (opt == IPOPT_NOP)
  827                                     len = 1;
  828                             else {
  829                                     if (cnt < IPOPT_OLEN + sizeof(*cp))
  830                                             break;
  831                                     len = cp[IPOPT_OLEN];
  832                                     if (len < IPOPT_OLEN + sizeof(*cp) ||
  833                                         len > cnt)
  834                                             break;
  835                             }
  836                             /*
  837                              * Should check for overflow, but it "can't happen"
  838                              */
  839                             if (opt == IPOPT_RR || opt == IPOPT_TS ||
  840                                 opt == IPOPT_SECURITY) {
  841                                     bcopy((caddr_t)cp,
  842                                         mtod(opts, caddr_t) + opts->m_len, len);
  843                                     opts->m_len += len;
  844                             }
  845                     }
  846                     /* Terminate & pad, if necessary */
  847                     cnt = opts->m_len % 4;
  848                     if (cnt) {
  849                             for (; cnt < 4; cnt++) {
  850                                     *(mtod(opts, caddr_t) + opts->m_len) =
  851                                         IPOPT_EOL;
  852                                     opts->m_len++;
  853                             }
  854                     }
  855 #ifdef ICMPPRINTFS
  856                     if (icmpprintfs)
  857                             printf("%d\n", opts->m_len);
  858 #endif
  859                 }
  860                 /*
  861                  * Now strip out original options by copying rest of first
  862                  * mbuf's data back, and adjust the IP length.
  863                  */
  864                 ip->ip_len -= optlen;
  865                 ip->ip_v = IPVERSION;
  866                 ip->ip_hl = 5;
  867                 m->m_len -= optlen;
  868                 if (m->m_flags & M_PKTHDR)
  869                         m->m_pkthdr.len -= optlen;
  870                 optlen += sizeof(struct ip);
  871                 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
  872                          (unsigned)(m->m_len - sizeof(struct ip)));
  873         }
  874         m_tag_delete_nonpersistent(m);
  875         m->m_flags &= ~(M_BCAST|M_MCAST);
  876         icmp_send(m, opts);
  877 done:
  878         if (opts)
  879                 (void)m_free(opts);
  880 }
  881 
  882 /*
  883  * Send an icmp packet back to the ip level,
  884  * after supplying a checksum.
  885  */
  886 static void
  887 icmp_send(struct mbuf *m, struct mbuf *opts)
  888 {
  889         register struct ip *ip = mtod(m, struct ip *);
  890         register int hlen;
  891         register struct icmp *icp;
  892 
  893         hlen = ip->ip_hl << 2;
  894         m->m_data += hlen;
  895         m->m_len -= hlen;
  896         icp = mtod(m, struct icmp *);
  897         icp->icmp_cksum = 0;
  898         icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
  899         m->m_data -= hlen;
  900         m->m_len += hlen;
  901         m->m_pkthdr.rcvif = (struct ifnet *)0;
  902 #ifdef ICMPPRINTFS
  903         if (icmpprintfs) {
  904                 char buf[4 * sizeof "123"];
  905                 strcpy(buf, inet_ntoa(ip->ip_dst));
  906                 printf("icmp_send dst %s src %s\n",
  907                        buf, inet_ntoa(ip->ip_src));
  908         }
  909 #endif
  910         (void) ip_output(m, opts, NULL, 0, NULL, NULL);
  911 }
  912 
  913 /*
  914  * Return milliseconds since 00:00 GMT in network format.
  915  */
  916 uint32_t
  917 iptime(void)
  918 {
  919         struct timeval atv;
  920         u_long t;
  921 
  922         getmicrotime(&atv);
  923         t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
  924         return (htonl(t));
  925 }
  926 
  927 /*
  928  * Return the next larger or smaller MTU plateau (table from RFC 1191)
  929  * given current value MTU.  If DIR is less than zero, a larger plateau
  930  * is returned; otherwise, a smaller value is returned.
  931  */
  932 int
  933 ip_next_mtu(int mtu, int dir)
  934 {
  935         static int mtutab[] = {
  936                 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
  937                 296, 68, 0
  938         };
  939         int i, size;
  940 
  941         size = (sizeof mtutab) / (sizeof mtutab[0]);
  942         if (dir >= 0) {
  943                 for (i = 0; i < size; i++)
  944                         if (mtu > mtutab[i])
  945                                 return mtutab[i];
  946         } else {
  947                 for (i = size - 1; i >= 0; i--)
  948                         if (mtu < mtutab[i])
  949                                 return mtutab[i];
  950                 if (mtu == mtutab[0])
  951                         return mtutab[0];
  952         }
  953         return 0;
  954 }
  955 
  956 
  957 /*
  958  * badport_bandlim() - check for ICMP bandwidth limit
  959  *
  960  *      Return 0 if it is ok to send an ICMP error response, -1 if we have
  961  *      hit our bandwidth limit and it is not ok.
  962  *
  963  *      If icmplim is <= 0, the feature is disabled and 0 is returned.
  964  *
  965  *      For now we separate the TCP and UDP subsystems w/ different 'which'
  966  *      values.  We may eventually remove this separation (and simplify the
  967  *      code further).
  968  *
  969  *      Note that the printing of the error message is delayed so we can
  970  *      properly print the icmp error rate that the system was trying to do
  971  *      (i.e. 22000/100 pps, etc...).  This can cause long delays in printing
  972  *      the 'final' error, but it doesn't make sense to solve the printing
  973  *      delay with more complex code.
  974  */
  975 
  976 int
  977 badport_bandlim(int which)
  978 {
  979 
  980 #define N(a)    (sizeof (a) / sizeof (a[0]))
  981         static struct rate {
  982                 const char      *type;
  983                 struct timeval  lasttime;
  984                 int             curpps;
  985         } rates[BANDLIM_MAX+1] = {
  986                 { "icmp unreach response" },
  987                 { "icmp ping response" },
  988                 { "icmp tstamp response" },
  989                 { "closed port RST response" },
  990                 { "open port RST response" },
  991                 { "icmp6 unreach response" },
  992                 { "sctp ootb response" }
  993         };
  994 
  995         /*
  996          * Return ok status if feature disabled or argument out of range.
  997          */
  998         if (V_icmplim > 0 && (u_int) which < N(rates)) {
  999                 struct rate *r = &rates[which];
 1000                 int opps = r->curpps;
 1001 
 1002                 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
 1003                         return -1;      /* discard packet */
 1004                 /*
 1005                  * If we've dropped below the threshold after having
 1006                  * rate-limited traffic print the message.  This preserves
 1007                  * the previous behaviour at the expense of added complexity.
 1008                  */
 1009                 if (V_icmplim_output && opps > V_icmplim)
 1010                         log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
 1011                                 r->type, opps, V_icmplim);
 1012         }
 1013         return 0;                       /* okay to send packet */
 1014 #undef N
 1015 }

Cache object: f86b154a984c400f1270e51177543ec6


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