The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/if_ether.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  *      @(#)if_ether.c  8.1 (Berkeley) 6/10/93
   30  */
   31 
   32 /*
   33  * Ethernet address resolution protocol.
   34  * TODO:
   35  *      add "inuse/lock" bit (or ref. count) along with valid bit
   36  */
   37 
   38 #include <sys/cdefs.h>
   39 __FBSDID("$FreeBSD: releng/10.1/sys/netinet/if_ether.c 267175 2014-06-06 17:42:55Z asomers $");
   40 
   41 #include "opt_inet.h"
   42 
   43 #include <sys/param.h>
   44 #include <sys/kernel.h>
   45 #include <sys/queue.h>
   46 #include <sys/sysctl.h>
   47 #include <sys/systm.h>
   48 #include <sys/mbuf.h>
   49 #include <sys/malloc.h>
   50 #include <sys/proc.h>
   51 #include <sys/socket.h>
   52 #include <sys/syslog.h>
   53 
   54 #include <net/if.h>
   55 #include <net/if_dl.h>
   56 #include <net/if_types.h>
   57 #include <net/netisr.h>
   58 #include <net/if_llc.h>
   59 #include <net/ethernet.h>
   60 #include <net/route.h>
   61 #include <net/vnet.h>
   62 
   63 #include <netinet/in.h>
   64 #include <netinet/in_var.h>
   65 #include <net/if_llatbl.h>
   66 #include <netinet/if_ether.h>
   67 #ifdef INET
   68 #include <netinet/ip_carp.h>
   69 #endif
   70 
   71 #include <net/if_arc.h>
   72 #include <net/iso88025.h>
   73 
   74 #include <security/mac/mac_framework.h>
   75 
   76 #define SIN(s) ((const struct sockaddr_in *)(s))
   77 #define SDL(s) ((struct sockaddr_dl *)s)
   78 
   79 SYSCTL_DECL(_net_link_ether);
   80 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
   81 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, "");
   82 
   83 /* timer values */
   84 static VNET_DEFINE(int, arpt_keep) = (20*60);   /* once resolved, good for 20
   85                                                  * minutes */
   86 static VNET_DEFINE(int, arp_maxtries) = 5;
   87 VNET_DEFINE(int, useloopback) = 1;      /* use loopback interface for
   88                                          * local traffic */
   89 static VNET_DEFINE(int, arp_proxyall) = 0;
   90 static VNET_DEFINE(int, arpt_down) = 20;        /* keep incomplete entries for
   91                                                  * 20 seconds */
   92 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat);  /* ARP statistics, see if_arp.h */
   93 VNET_PCPUSTAT_SYSINIT(arpstat);
   94 
   95 #ifdef VIMAGE
   96 VNET_PCPUSTAT_SYSUNINIT(arpstat);
   97 #endif /* VIMAGE */
   98 
   99 static VNET_DEFINE(int, arp_maxhold) = 1;
  100 
  101 #define V_arpt_keep             VNET(arpt_keep)
  102 #define V_arpt_down             VNET(arpt_down)
  103 #define V_arp_maxtries          VNET(arp_maxtries)
  104 #define V_arp_proxyall          VNET(arp_proxyall)
  105 #define V_arp_maxhold           VNET(arp_maxhold)
  106 
  107 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
  108         &VNET_NAME(arpt_keep), 0,
  109         "ARP entry lifetime in seconds");
  110 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
  111         &VNET_NAME(arp_maxtries), 0,
  112         "ARP resolution attempts before returning error");
  113 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
  114         &VNET_NAME(useloopback), 0,
  115         "Use the loopback interface for local traffic");
  116 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
  117         &VNET_NAME(arp_proxyall), 0,
  118         "Enable proxy ARP for all suitable requests");
  119 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_RW,
  120         &VNET_NAME(arpt_down), 0,
  121         "Incomplete ARP entry lifetime in seconds");
  122 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat,
  123     arpstat, "ARP statistics (struct arpstat, net/if_arp.h)");
  124 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_RW,
  125         &VNET_NAME(arp_maxhold), 0,
  126         "Number of packets to hold per ARP entry");
  127 
  128 static void     arp_init(void);
  129 static void     arpintr(struct mbuf *);
  130 static void     arptimer(void *);
  131 #ifdef INET
  132 static void     in_arpinput(struct mbuf *);
  133 #endif
  134 
  135 static const struct netisr_handler arp_nh = {
  136         .nh_name = "arp",
  137         .nh_handler = arpintr,
  138         .nh_proto = NETISR_ARP,
  139         .nh_policy = NETISR_POLICY_SOURCE,
  140 };
  141 
  142 #ifdef AF_INET
  143 /*
  144  * called by in_ifscrub to remove entry from the table when
  145  * the interface goes away
  146  */
  147 void
  148 arp_ifscrub(struct ifnet *ifp, uint32_t addr)
  149 {
  150         struct sockaddr_in addr4;
  151 
  152         bzero((void *)&addr4, sizeof(addr4));
  153         addr4.sin_len    = sizeof(addr4);
  154         addr4.sin_family = AF_INET;
  155         addr4.sin_addr.s_addr = addr;
  156         IF_AFDATA_RLOCK(ifp);
  157         lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
  158             (struct sockaddr *)&addr4);
  159         IF_AFDATA_RUNLOCK(ifp);
  160 }
  161 #endif
  162 
  163 /*
  164  * Timeout routine.  Age arp_tab entries periodically.
  165  */
  166 static void
  167 arptimer(void *arg)
  168 {
  169         struct llentry *lle = (struct llentry *)arg;
  170         struct ifnet *ifp;
  171 
  172         if (lle->la_flags & LLE_STATIC) {
  173                 LLE_WUNLOCK(lle);
  174                 return;
  175         }
  176 
  177         ifp = lle->lle_tbl->llt_ifp;
  178         CURVNET_SET(ifp->if_vnet);
  179 
  180         if ((lle->la_flags & LLE_DELETED) == 0) {
  181                 int evt;
  182 
  183                 if (lle->la_flags & LLE_VALID)
  184                         evt = LLENTRY_EXPIRED;
  185                 else
  186                         evt = LLENTRY_TIMEDOUT;
  187                 EVENTHANDLER_INVOKE(lle_event, lle, evt);
  188         }
  189 
  190         callout_stop(&lle->la_timer);
  191 
  192         /* XXX: LOR avoidance. We still have ref on lle. */
  193         LLE_WUNLOCK(lle);
  194         IF_AFDATA_LOCK(ifp);
  195         LLE_WLOCK(lle);
  196 
  197         /* Guard against race with other llentry_free(). */
  198         if (lle->la_flags & LLE_LINKED) {
  199                 size_t pkts_dropped;
  200 
  201                 LLE_REMREF(lle);
  202                 pkts_dropped = llentry_free(lle);
  203                 ARPSTAT_ADD(dropped, pkts_dropped);
  204         } else
  205                 LLE_FREE_LOCKED(lle);
  206 
  207         IF_AFDATA_UNLOCK(ifp);
  208 
  209         ARPSTAT_INC(timeouts);
  210 
  211         CURVNET_RESTORE();
  212 }
  213 
  214 /*
  215  * Broadcast an ARP request. Caller specifies:
  216  *      - arp header source ip address
  217  *      - arp header target ip address
  218  *      - arp header source ethernet address
  219  */
  220 void
  221 arprequest(struct ifnet *ifp, const struct in_addr *sip,
  222     const struct in_addr *tip, u_char *enaddr)
  223 {
  224         struct mbuf *m;
  225         struct arphdr *ah;
  226         struct sockaddr sa;
  227         u_char *carpaddr = NULL;
  228 
  229         if (sip == NULL) {
  230                 /*
  231                  * The caller did not supply a source address, try to find
  232                  * a compatible one among those assigned to this interface.
  233                  */
  234                 struct ifaddr *ifa;
  235 
  236                 IF_ADDR_RLOCK(ifp);
  237                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  238                         if (ifa->ifa_addr->sa_family != AF_INET)
  239                                 continue;
  240 
  241                         if (ifa->ifa_carp) {
  242                                 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
  243                                         continue;
  244                                 sip = &IA_SIN(ifa)->sin_addr;
  245                         } else {
  246                                 carpaddr = NULL;
  247                                 sip = &IA_SIN(ifa)->sin_addr;
  248                         }
  249 
  250                         if (0 == ((sip->s_addr ^ tip->s_addr) &
  251                             IA_MASKSIN(ifa)->sin_addr.s_addr))
  252                                 break;  /* found it. */
  253                 }
  254                 IF_ADDR_RUNLOCK(ifp);
  255                 if (sip == NULL) {
  256                         printf("%s: cannot find matching address\n", __func__);
  257                         return;
  258                 }
  259         }
  260         if (enaddr == NULL)
  261                 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
  262 
  263         if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
  264                 return;
  265         m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
  266                 2*ifp->if_data.ifi_addrlen;
  267         m->m_pkthdr.len = m->m_len;
  268         MH_ALIGN(m, m->m_len);
  269         ah = mtod(m, struct arphdr *);
  270         bzero((caddr_t)ah, m->m_len);
  271 #ifdef MAC
  272         mac_netinet_arp_send(ifp, m);
  273 #endif
  274         ah->ar_pro = htons(ETHERTYPE_IP);
  275         ah->ar_hln = ifp->if_addrlen;           /* hardware address length */
  276         ah->ar_pln = sizeof(struct in_addr);    /* protocol address length */
  277         ah->ar_op = htons(ARPOP_REQUEST);
  278         bcopy(enaddr, ar_sha(ah), ah->ar_hln);
  279         bcopy(sip, ar_spa(ah), ah->ar_pln);
  280         bcopy(tip, ar_tpa(ah), ah->ar_pln);
  281         sa.sa_family = AF_ARP;
  282         sa.sa_len = 2;
  283         m->m_flags |= M_BCAST;
  284         m_clrprotoflags(m);     /* Avoid confusing lower layers. */
  285         (*ifp->if_output)(ifp, m, &sa, NULL);
  286         ARPSTAT_INC(txrequests);
  287 }
  288 
  289 /*
  290  * Resolve an IP address into an ethernet address.
  291  * On input:
  292  *    ifp is the interface we use
  293  *    rt0 is the route to the final destination (possibly useless)
  294  *    m is the mbuf. May be NULL if we don't have a packet.
  295  *    dst is the next hop,
  296  *    desten is where we want the address.
  297  *
  298  * On success, desten is filled in and the function returns 0;
  299  * If the packet must be held pending resolution, we return EWOULDBLOCK
  300  * On other errors, we return the corresponding error code.
  301  * Note that m_freem() handles NULL.
  302  */
  303 int
  304 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
  305         const struct sockaddr *dst, u_char *desten, struct llentry **lle)
  306 {
  307         struct llentry *la = 0;
  308         u_int flags = 0;
  309         struct mbuf *curr = NULL;
  310         struct mbuf *next = NULL;
  311         int error, renew;
  312 
  313         *lle = NULL;
  314         if (m != NULL) {
  315                 if (m->m_flags & M_BCAST) {
  316                         /* broadcast */
  317                         (void)memcpy(desten,
  318                             ifp->if_broadcastaddr, ifp->if_addrlen);
  319                         return (0);
  320                 }
  321                 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
  322                         /* multicast */
  323                         ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
  324                         return (0);
  325                 }
  326         }
  327 retry:
  328         IF_AFDATA_RLOCK(ifp);
  329         la = lla_lookup(LLTABLE(ifp), flags, dst);
  330         IF_AFDATA_RUNLOCK(ifp);
  331         if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
  332             && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
  333                 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
  334                 IF_AFDATA_WLOCK(ifp);
  335                 la = lla_lookup(LLTABLE(ifp), flags, dst);
  336                 IF_AFDATA_WUNLOCK(ifp);
  337         }
  338         if (la == NULL) {
  339                 if (flags & LLE_CREATE)
  340                         log(LOG_DEBUG,
  341                             "arpresolve: can't allocate llinfo for %s on %s\n",
  342                             inet_ntoa(SIN(dst)->sin_addr), ifp->if_xname);
  343                 m_freem(m);
  344                 return (EINVAL);
  345         }
  346 
  347         if ((la->la_flags & LLE_VALID) &&
  348             ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
  349                 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
  350                 /*
  351                  * If entry has an expiry time and it is approaching,
  352                  * see if we need to send an ARP request within this
  353                  * arpt_down interval.
  354                  */
  355                 if (!(la->la_flags & LLE_STATIC) &&
  356                     time_uptime + la->la_preempt > la->la_expire) {
  357                         arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
  358                         la->la_preempt--;
  359                 }
  360 
  361                 *lle = la;
  362                 error = 0;
  363                 goto done;
  364         }
  365 
  366         if (la->la_flags & LLE_STATIC) {   /* should not happen! */
  367                 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
  368                     inet_ntoa(SIN(dst)->sin_addr));
  369                 m_freem(m);
  370                 error = EINVAL;
  371                 goto done;
  372         }
  373 
  374         renew = (la->la_asked == 0 || la->la_expire != time_uptime);
  375         if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
  376                 flags |= LLE_EXCLUSIVE;
  377                 LLE_RUNLOCK(la);
  378                 goto retry;
  379         }
  380         /*
  381          * There is an arptab entry, but no ethernet address
  382          * response yet.  Add the mbuf to the list, dropping
  383          * the oldest packet if we have exceeded the system
  384          * setting.
  385          */
  386         if (m != NULL) {
  387                 if (la->la_numheld >= V_arp_maxhold) {
  388                         if (la->la_hold != NULL) {
  389                                 next = la->la_hold->m_nextpkt;
  390                                 m_freem(la->la_hold);
  391                                 la->la_hold = next;
  392                                 la->la_numheld--;
  393                                 ARPSTAT_INC(dropped);
  394                         }
  395                 }
  396                 if (la->la_hold != NULL) {
  397                         curr = la->la_hold;
  398                         while (curr->m_nextpkt != NULL)
  399                                 curr = curr->m_nextpkt;
  400                         curr->m_nextpkt = m;
  401                 } else
  402                         la->la_hold = m;
  403                 la->la_numheld++;
  404                 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
  405                         flags &= ~LLE_EXCLUSIVE;
  406                         LLE_DOWNGRADE(la);
  407                 }
  408 
  409         }
  410         /*
  411          * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
  412          * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
  413          * if we have already sent arp_maxtries ARP requests. Retransmit the
  414          * ARP request, but not faster than one request per second.
  415          */
  416         if (la->la_asked < V_arp_maxtries)
  417                 error = EWOULDBLOCK;    /* First request. */
  418         else
  419                 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ?
  420                     EHOSTUNREACH : EHOSTDOWN;
  421 
  422         if (renew) {
  423                 int canceled;
  424 
  425                 LLE_ADDREF(la);
  426                 la->la_expire = time_uptime;
  427                 canceled = callout_reset(&la->la_timer, hz * V_arpt_down,
  428                     arptimer, la);
  429                 if (canceled)
  430                         LLE_REMREF(la);
  431                 la->la_asked++;
  432                 LLE_WUNLOCK(la);
  433                 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
  434                 return (error);
  435         }
  436 done:
  437         if (flags & LLE_EXCLUSIVE)
  438                 LLE_WUNLOCK(la);
  439         else
  440                 LLE_RUNLOCK(la);
  441         return (error);
  442 }
  443 
  444 /*
  445  * Common length and type checks are done here,
  446  * then the protocol-specific routine is called.
  447  */
  448 static void
  449 arpintr(struct mbuf *m)
  450 {
  451         struct arphdr *ar;
  452 
  453         if (m->m_len < sizeof(struct arphdr) &&
  454             ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
  455                 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n");
  456                 return;
  457         }
  458         ar = mtod(m, struct arphdr *);
  459 
  460         if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
  461             ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
  462             ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
  463             ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 &&
  464             ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) {
  465                 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)"
  466                     " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "",
  467                     ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":",
  468                     ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":");
  469                 m_freem(m);
  470                 return;
  471         }
  472 
  473         if (m->m_len < arphdr_len(ar)) {
  474                 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
  475                         log(LOG_NOTICE, "arp: runt packet\n");
  476                         m_freem(m);
  477                         return;
  478                 }
  479                 ar = mtod(m, struct arphdr *);
  480         }
  481 
  482         ARPSTAT_INC(received);
  483         switch (ntohs(ar->ar_pro)) {
  484 #ifdef INET
  485         case ETHERTYPE_IP:
  486                 in_arpinput(m);
  487                 return;
  488 #endif
  489         }
  490         m_freem(m);
  491 }
  492 
  493 #ifdef INET
  494 /*
  495  * ARP for Internet protocols on 10 Mb/s Ethernet.
  496  * Algorithm is that given in RFC 826.
  497  * In addition, a sanity check is performed on the sender
  498  * protocol address, to catch impersonators.
  499  * We no longer handle negotiations for use of trailer protocol:
  500  * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
  501  * along with IP replies if we wanted trailers sent to us,
  502  * and also sent them in response to IP replies.
  503  * This allowed either end to announce the desire to receive
  504  * trailer packets.
  505  * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
  506  * but formerly didn't normally send requests.
  507  */
  508 static int log_arp_wrong_iface = 1;
  509 static int log_arp_movements = 1;
  510 static int log_arp_permanent_modify = 1;
  511 static int allow_multicast = 0;
  512 static struct timeval arp_lastlog;
  513 static int arp_curpps;
  514 static int arp_maxpps = 1;
  515 
  516 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
  517         &log_arp_wrong_iface, 0,
  518         "log arp packets arriving on the wrong interface");
  519 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
  520         &log_arp_movements, 0,
  521         "log arp replies from MACs different than the one in the cache");
  522 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
  523         &log_arp_permanent_modify, 0,
  524         "log arp replies from MACs different than the one in the permanent arp entry");
  525 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
  526         &allow_multicast, 0, "accept multicast addresses");
  527 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second,
  528         CTLFLAG_RW, &arp_maxpps, 0,
  529         "Maximum number of remotely triggered ARP messages that can be "
  530         "logged per second");
  531 
  532 #define ARP_LOG(pri, ...)       do {                                    \
  533         if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps))        \
  534                 log((pri), "arp: " __VA_ARGS__);                        \
  535 } while (0)
  536 
  537 static void
  538 in_arpinput(struct mbuf *m)
  539 {
  540         struct arphdr *ah;
  541         struct ifnet *ifp = m->m_pkthdr.rcvif;
  542         struct llentry *la = NULL;
  543         struct rtentry *rt;
  544         struct ifaddr *ifa;
  545         struct in_ifaddr *ia;
  546         struct sockaddr sa;
  547         struct in_addr isaddr, itaddr, myaddr;
  548         u_int8_t *enaddr = NULL;
  549         int op, flags;
  550         int req_len;
  551         int bridged = 0, is_bridge = 0;
  552         int carped;
  553         struct sockaddr_in sin;
  554         sin.sin_len = sizeof(struct sockaddr_in);
  555         sin.sin_family = AF_INET;
  556         sin.sin_addr.s_addr = 0;
  557 
  558         if (ifp->if_bridge)
  559                 bridged = 1;
  560         if (ifp->if_type == IFT_BRIDGE)
  561                 is_bridge = 1;
  562 
  563         req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
  564         if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
  565                 ARP_LOG(LOG_NOTICE, "runt packet -- m_pullup failed\n");
  566                 return;
  567         }
  568 
  569         ah = mtod(m, struct arphdr *);
  570         /*
  571          * ARP is only for IPv4 so we can reject packets with
  572          * a protocol length not equal to an IPv4 address.
  573          */
  574         if (ah->ar_pln != sizeof(struct in_addr)) {
  575                 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
  576                     sizeof(struct in_addr));
  577                 goto drop;
  578         }
  579 
  580         if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
  581                 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
  582                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
  583                 goto drop;
  584         }
  585 
  586         op = ntohs(ah->ar_op);
  587         (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
  588         (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
  589 
  590         if (op == ARPOP_REPLY)
  591                 ARPSTAT_INC(rxreplies);
  592 
  593         /*
  594          * For a bridge, we want to check the address irrespective
  595          * of the receive interface. (This will change slightly
  596          * when we have clusters of interfaces).
  597          */
  598         IN_IFADDR_RLOCK();
  599         LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  600                 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
  601                     ia->ia_ifp == ifp) &&
  602                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
  603                     (ia->ia_ifa.ifa_carp == NULL ||
  604                     (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
  605                         ifa_ref(&ia->ia_ifa);
  606                         IN_IFADDR_RUNLOCK();
  607                         goto match;
  608                 }
  609         }
  610         LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
  611                 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
  612                     ia->ia_ifp == ifp) &&
  613                     isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  614                         ifa_ref(&ia->ia_ifa);
  615                         IN_IFADDR_RUNLOCK();
  616                         goto match;
  617                 }
  618 
  619 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia)                           \
  620   (ia->ia_ifp->if_bridge == ifp->if_softc &&                            \
  621   !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) &&      \
  622   addr == ia->ia_addr.sin_addr.s_addr)
  623         /*
  624          * Check the case when bridge shares its MAC address with
  625          * some of its children, so packets are claimed by bridge
  626          * itself (bridge_input() does it first), but they are really
  627          * meant to be destined to the bridge member.
  628          */
  629         if (is_bridge) {
  630                 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  631                         if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
  632                                 ifa_ref(&ia->ia_ifa);
  633                                 ifp = ia->ia_ifp;
  634                                 IN_IFADDR_RUNLOCK();
  635                                 goto match;
  636                         }
  637                 }
  638         }
  639 #undef BDG_MEMBER_MATCHES_ARP
  640         IN_IFADDR_RUNLOCK();
  641 
  642         /*
  643          * No match, use the first inet address on the receive interface
  644          * as a dummy address for the rest of the function.
  645          */
  646         IF_ADDR_RLOCK(ifp);
  647         TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
  648                 if (ifa->ifa_addr->sa_family == AF_INET &&
  649                     (ifa->ifa_carp == NULL ||
  650                     (*carp_iamatch_p)(ifa, &enaddr))) {
  651                         ia = ifatoia(ifa);
  652                         ifa_ref(ifa);
  653                         IF_ADDR_RUNLOCK(ifp);
  654                         goto match;
  655                 }
  656         IF_ADDR_RUNLOCK(ifp);
  657 
  658         /*
  659          * If bridging, fall back to using any inet address.
  660          */
  661         IN_IFADDR_RLOCK();
  662         if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
  663                 IN_IFADDR_RUNLOCK();
  664                 goto drop;
  665         }
  666         ifa_ref(&ia->ia_ifa);
  667         IN_IFADDR_RUNLOCK();
  668 match:
  669         if (!enaddr)
  670                 enaddr = (u_int8_t *)IF_LLADDR(ifp);
  671         carped = (ia->ia_ifa.ifa_carp != NULL);
  672         myaddr = ia->ia_addr.sin_addr;
  673         ifa_free(&ia->ia_ifa);
  674         if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
  675                 goto drop;      /* it's from me, ignore it. */
  676         if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
  677                 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
  678                     "%s!\n", inet_ntoa(isaddr));
  679                 goto drop;
  680         }
  681         /*
  682          * Warn if another host is using the same IP address, but only if the
  683          * IP address isn't 0.0.0.0, which is used for DHCP only, in which
  684          * case we suppress the warning to avoid false positive complaints of
  685          * potential misconfiguration.
  686          */
  687         if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
  688             myaddr.s_addr != 0) {
  689                 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
  690                    ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  691                    inet_ntoa(isaddr), ifp->if_xname);
  692                 itaddr = myaddr;
  693                 ARPSTAT_INC(dupips);
  694                 goto reply;
  695         }
  696         if (ifp->if_flags & IFF_STATICARP)
  697                 goto reply;
  698 
  699         bzero(&sin, sizeof(sin));
  700         sin.sin_len = sizeof(struct sockaddr_in);
  701         sin.sin_family = AF_INET;
  702         sin.sin_addr = isaddr;
  703         flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
  704         flags |= LLE_EXCLUSIVE;
  705         IF_AFDATA_LOCK(ifp);
  706         la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
  707         IF_AFDATA_UNLOCK(ifp);
  708         if (la != NULL) {
  709                 /* the following is not an error when doing bridging */
  710                 if (!bridged && la->lle_tbl->llt_ifp != ifp) {
  711                         if (log_arp_wrong_iface)
  712                                 ARP_LOG(LOG_WARNING, "%s is on %s "
  713                                     "but got reply from %*D on %s\n",
  714                                     inet_ntoa(isaddr),
  715                                     la->lle_tbl->llt_ifp->if_xname,
  716                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  717                                     ifp->if_xname);
  718                         LLE_WUNLOCK(la);
  719                         goto reply;
  720                 }
  721                 if ((la->la_flags & LLE_VALID) &&
  722                     bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
  723                         if (la->la_flags & LLE_STATIC) {
  724                                 LLE_WUNLOCK(la);
  725                                 if (log_arp_permanent_modify)
  726                                         ARP_LOG(LOG_ERR,
  727                                             "%*D attempts to modify "
  728                                             "permanent entry for %s on %s\n",
  729                                             ifp->if_addrlen,
  730                                             (u_char *)ar_sha(ah), ":",
  731                                             inet_ntoa(isaddr), ifp->if_xname);
  732                                 goto reply;
  733                         }
  734                         if (log_arp_movements) {
  735                                 ARP_LOG(LOG_INFO, "%s moved from %*D "
  736                                     "to %*D on %s\n",
  737                                     inet_ntoa(isaddr),
  738                                     ifp->if_addrlen,
  739                                     (u_char *)&la->ll_addr, ":",
  740                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  741                                     ifp->if_xname);
  742                         }
  743                 }
  744 
  745                 if (ifp->if_addrlen != ah->ar_hln) {
  746                         LLE_WUNLOCK(la);
  747                         ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
  748                             "i/f %d (ignored)\n", ifp->if_addrlen,
  749                             (u_char *) ar_sha(ah), ":", ah->ar_hln,
  750                             ifp->if_addrlen);
  751                         goto drop;
  752                 }
  753                 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
  754                 la->la_flags |= LLE_VALID;
  755 
  756                 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
  757 
  758                 if (!(la->la_flags & LLE_STATIC)) {
  759                         int canceled;
  760 
  761                         LLE_ADDREF(la);
  762                         la->la_expire = time_uptime + V_arpt_keep;
  763                         canceled = callout_reset(&la->la_timer,
  764                             hz * V_arpt_keep, arptimer, la);
  765                         if (canceled)
  766                                 LLE_REMREF(la);
  767                 }
  768                 la->la_asked = 0;
  769                 la->la_preempt = V_arp_maxtries;
  770                 /*
  771                  * The packets are all freed within the call to the output
  772                  * routine.
  773                  *
  774                  * NB: The lock MUST be released before the call to the
  775                  * output routine.
  776                  */
  777                 if (la->la_hold != NULL) {
  778                         struct mbuf *m_hold, *m_hold_next;
  779 
  780                         m_hold = la->la_hold;
  781                         la->la_hold = NULL;
  782                         la->la_numheld = 0;
  783                         memcpy(&sa, L3_ADDR(la), sizeof(sa));
  784                         LLE_WUNLOCK(la);
  785                         for (; m_hold != NULL; m_hold = m_hold_next) {
  786                                 m_hold_next = m_hold->m_nextpkt;
  787                                 m_hold->m_nextpkt = NULL;
  788                                 /* Avoid confusing lower layers. */
  789                                 m_clrprotoflags(m_hold);
  790                                 (*ifp->if_output)(ifp, m_hold, &sa, NULL);
  791                         }
  792                 } else
  793                         LLE_WUNLOCK(la);
  794         }
  795 reply:
  796         if (op != ARPOP_REQUEST)
  797                 goto drop;
  798         ARPSTAT_INC(rxrequests);
  799 
  800         if (itaddr.s_addr == myaddr.s_addr) {
  801                 /* Shortcut.. the receiving interface is the target. */
  802                 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  803                 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  804         } else {
  805                 struct llentry *lle = NULL;
  806 
  807                 sin.sin_addr = itaddr;
  808                 IF_AFDATA_RLOCK(ifp);
  809                 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
  810                 IF_AFDATA_RUNLOCK(ifp);
  811 
  812                 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
  813                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  814                         (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
  815                         LLE_RUNLOCK(lle);
  816                 } else {
  817 
  818                         if (lle != NULL)
  819                                 LLE_RUNLOCK(lle);
  820 
  821                         if (!V_arp_proxyall)
  822                                 goto drop;
  823 
  824                         sin.sin_addr = itaddr;
  825                         /* XXX MRT use table 0 for arp reply  */
  826                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  827                         if (!rt)
  828                                 goto drop;
  829 
  830                         /*
  831                          * Don't send proxies for nodes on the same interface
  832                          * as this one came out of, or we'll get into a fight
  833                          * over who claims what Ether address.
  834                          */
  835                         if (!rt->rt_ifp || rt->rt_ifp == ifp) {
  836                                 RTFREE_LOCKED(rt);
  837                                 goto drop;
  838                         }
  839                         RTFREE_LOCKED(rt);
  840 
  841                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  842                         (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  843 
  844                         /*
  845                          * Also check that the node which sent the ARP packet
  846                          * is on the interface we expect it to be on. This
  847                          * avoids ARP chaos if an interface is connected to the
  848                          * wrong network.
  849                          */
  850                         sin.sin_addr = isaddr;
  851 
  852                         /* XXX MRT use table 0 for arp checks */
  853                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  854                         if (!rt)
  855                                 goto drop;
  856                         if (rt->rt_ifp != ifp) {
  857                                 ARP_LOG(LOG_INFO, "proxy: ignoring request"
  858                                     " from %s via %s, expecting %s\n",
  859                                     inet_ntoa(isaddr), ifp->if_xname,
  860                                     rt->rt_ifp->if_xname);
  861                                 RTFREE_LOCKED(rt);
  862                                 goto drop;
  863                         }
  864                         RTFREE_LOCKED(rt);
  865 
  866 #ifdef DEBUG_PROXY
  867                         printf("arp: proxying for %s\n", inet_ntoa(itaddr));
  868 #endif
  869                 }
  870         }
  871 
  872         if (itaddr.s_addr == myaddr.s_addr &&
  873             IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
  874                 /* RFC 3927 link-local IPv4; always reply by broadcast. */
  875 #ifdef DEBUG_LINKLOCAL
  876                 printf("arp: sending reply for link-local addr %s\n",
  877                     inet_ntoa(itaddr));
  878 #endif
  879                 m->m_flags |= M_BCAST;
  880                 m->m_flags &= ~M_MCAST;
  881         } else {
  882                 /* default behaviour; never reply by broadcast. */
  883                 m->m_flags &= ~(M_BCAST|M_MCAST);
  884         }
  885         (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
  886         (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
  887         ah->ar_op = htons(ARPOP_REPLY);
  888         ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
  889         m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
  890         m->m_pkthdr.len = m->m_len;
  891         m->m_pkthdr.rcvif = NULL;
  892         sa.sa_family = AF_ARP;
  893         sa.sa_len = 2;
  894         m_clrprotoflags(m);     /* Avoid confusing lower layers. */
  895         (*ifp->if_output)(ifp, m, &sa, NULL);
  896         ARPSTAT_INC(txreplies);
  897         return;
  898 
  899 drop:
  900         m_freem(m);
  901 }
  902 #endif
  903 
  904 void
  905 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
  906 {
  907         struct llentry *lle;
  908 
  909         if (ifa->ifa_carp != NULL)
  910                 return;
  911 
  912         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
  913                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
  914                                 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
  915                 /*
  916                  * interface address is considered static entry
  917                  * because the output of the arp utility shows
  918                  * that L2 entry as permanent
  919                  */
  920                 IF_AFDATA_LOCK(ifp);
  921                 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
  922                                  (struct sockaddr *)IA_SIN(ifa));
  923                 IF_AFDATA_UNLOCK(ifp);
  924                 if (lle == NULL)
  925                         log(LOG_INFO, "arp_ifinit: cannot create arp "
  926                             "entry for interface address\n");
  927                 else
  928                         LLE_RUNLOCK(lle);
  929         }
  930         ifa->ifa_rtrequest = NULL;
  931 }
  932 
  933 void
  934 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
  935 {
  936         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
  937                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
  938                                 &IA_SIN(ifa)->sin_addr, enaddr);
  939         ifa->ifa_rtrequest = NULL;
  940 }
  941 
  942 static void
  943 arp_init(void)
  944 {
  945 
  946         netisr_register(&arp_nh);
  947 }
  948 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);

Cache object: d495e57764095b6e505148874d93c2c7


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