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/8.2/sys/netinet/if_ether.c 215870 2010-11-26 15:45:34Z zec $");
   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 #if defined(INET) || defined(INET6)
   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) ((struct sockaddr_in *)s)
   77 #define SDL(s) ((struct sockaddr_dl *)s)
   78 
   79 SYSCTL_DECL(_net_link_ether);
   80 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
   81 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 static VNET_DEFINE(struct arpstat, arpstat);  /* ARP statistics, see if_arp.h */
   93 
   94 #define V_arpt_keep             VNET(arpt_keep)
   95 #define V_arpt_down             VNET(arpt_down)
   96 #define V_arp_maxtries          VNET(arp_maxtries)
   97 #define V_arp_proxyall          VNET(arp_proxyall)
   98 #define V_arpstat               VNET(arpstat)
   99 
  100 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
  101         &VNET_NAME(arpt_keep), 0,
  102         "ARP entry lifetime in seconds");
  103 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
  104         &VNET_NAME(arp_maxtries), 0,
  105         "ARP resolution attempts before returning error");
  106 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
  107         &VNET_NAME(useloopback), 0,
  108         "Use the loopback interface for local traffic");
  109 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
  110         &VNET_NAME(arp_proxyall), 0,
  111         "Enable proxy ARP for all suitable requests");
  112 SYSCTL_VNET_STRUCT(_net_link_ether_arp, OID_AUTO, stats, CTLFLAG_RW,
  113         &VNET_NAME(arpstat), arpstat,
  114         "ARP statistics (struct arpstat, net/if_arp.h)");
  115 
  116 static void     arp_init(void);
  117 void            arprequest(struct ifnet *,
  118                         struct in_addr *, struct in_addr *, u_char *);
  119 static void     arpintr(struct mbuf *);
  120 static void     arptimer(void *);
  121 #ifdef INET
  122 static void     in_arpinput(struct mbuf *);
  123 #endif
  124 
  125 static const struct netisr_handler arp_nh = {
  126         .nh_name = "arp",
  127         .nh_handler = arpintr,
  128         .nh_proto = NETISR_ARP,
  129         .nh_policy = NETISR_POLICY_SOURCE,
  130 };
  131 
  132 #ifdef AF_INET
  133 void arp_ifscrub(struct ifnet *ifp, uint32_t addr);
  134 
  135 /*
  136  * called by in_ifscrub to remove entry from the table when
  137  * the interface goes away
  138  */
  139 void
  140 arp_ifscrub(struct ifnet *ifp, uint32_t addr)
  141 {
  142         struct sockaddr_in addr4;
  143 
  144         bzero((void *)&addr4, sizeof(addr4));
  145         addr4.sin_len    = sizeof(addr4);
  146         addr4.sin_family = AF_INET;
  147         addr4.sin_addr.s_addr = addr;
  148         IF_AFDATA_LOCK(ifp);
  149         lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
  150             (struct sockaddr *)&addr4);
  151         IF_AFDATA_UNLOCK(ifp);
  152 }
  153 #endif
  154 
  155 /*
  156  * Timeout routine.  Age arp_tab entries periodically.
  157  */
  158 static void
  159 arptimer(void *arg)
  160 {
  161         struct ifnet *ifp;
  162         struct llentry   *lle;
  163 
  164         KASSERT(arg != NULL, ("%s: arg NULL", __func__));
  165         lle = (struct llentry *)arg;
  166         ifp = lle->lle_tbl->llt_ifp;
  167         CURVNET_SET(ifp->if_vnet);
  168         IF_AFDATA_LOCK(ifp);
  169         LLE_WLOCK(lle);
  170         if (lle->la_flags & LLE_STATIC)
  171                 LLE_WUNLOCK(lle);
  172         else {
  173                 if (!callout_pending(&lle->la_timer) &&
  174                     callout_active(&lle->la_timer)) {
  175                         callout_stop(&lle->la_timer);
  176                         LLE_REMREF(lle);
  177                         (void) llentry_free(lle);
  178                         ARPSTAT_INC(timeouts);
  179                 } 
  180 #ifdef DIAGNOSTIC
  181                 else {
  182                         struct sockaddr *l3addr = L3_ADDR(lle);
  183                         log(LOG_INFO, 
  184                             "arptimer issue: %p, IPv4 address: \"%s\"\n", lle,
  185                             inet_ntoa(
  186                                 ((const struct sockaddr_in *)l3addr)->sin_addr));
  187                 }
  188 #endif
  189         }
  190         IF_AFDATA_UNLOCK(ifp);
  191         CURVNET_RESTORE();
  192 }
  193 
  194 /*
  195  * Broadcast an ARP request. Caller specifies:
  196  *      - arp header source ip address
  197  *      - arp header target ip address
  198  *      - arp header source ethernet address
  199  */
  200 void
  201 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr  *tip,
  202     u_char *enaddr)
  203 {
  204         struct mbuf *m;
  205         struct arphdr *ah;
  206         struct sockaddr sa;
  207 
  208         if (sip == NULL) {
  209                 /* XXX don't believe this can happen (or explain why) */
  210                 /*
  211                  * The caller did not supply a source address, try to find
  212                  * a compatible one among those assigned to this interface.
  213                  */
  214                 struct ifaddr *ifa;
  215 
  216                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  217                         if (!ifa->ifa_addr ||
  218                             ifa->ifa_addr->sa_family != AF_INET)
  219                                 continue;
  220                         sip = &SIN(ifa->ifa_addr)->sin_addr;
  221                         if (0 == ((sip->s_addr ^ tip->s_addr) &
  222                             SIN(ifa->ifa_netmask)->sin_addr.s_addr) )
  223                                 break;  /* found it. */
  224                 }
  225                 if (sip == NULL) {  
  226                         printf("%s: cannot find matching address\n", __func__);
  227                         return;
  228                 }
  229         }
  230 
  231         if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
  232                 return;
  233         m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
  234                 2*ifp->if_data.ifi_addrlen;
  235         m->m_pkthdr.len = m->m_len;
  236         MH_ALIGN(m, m->m_len);
  237         ah = mtod(m, struct arphdr *);
  238         bzero((caddr_t)ah, m->m_len);
  239 #ifdef MAC
  240         mac_netinet_arp_send(ifp, m);
  241 #endif
  242         ah->ar_pro = htons(ETHERTYPE_IP);
  243         ah->ar_hln = ifp->if_addrlen;           /* hardware address length */
  244         ah->ar_pln = sizeof(struct in_addr);    /* protocol address length */
  245         ah->ar_op = htons(ARPOP_REQUEST);
  246         bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
  247         bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
  248         bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
  249         sa.sa_family = AF_ARP;
  250         sa.sa_len = 2;
  251         m->m_flags |= M_BCAST;
  252         (*ifp->if_output)(ifp, m, &sa, NULL);
  253         ARPSTAT_INC(txrequests);
  254 }
  255 
  256 /*
  257  * Resolve an IP address into an ethernet address.
  258  * On input:
  259  *    ifp is the interface we use
  260  *    rt0 is the route to the final destination (possibly useless)
  261  *    m is the mbuf. May be NULL if we don't have a packet.
  262  *    dst is the next hop,
  263  *    desten is where we want the address.
  264  *
  265  * On success, desten is filled in and the function returns 0;
  266  * If the packet must be held pending resolution, we return EWOULDBLOCK
  267  * On other errors, we return the corresponding error code.
  268  * Note that m_freem() handles NULL.
  269  */
  270 int
  271 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
  272         struct sockaddr *dst, u_char *desten, struct llentry **lle)
  273 {
  274         struct llentry *la = 0;
  275         u_int flags = 0;
  276         int error, renew;
  277 
  278         *lle = NULL;
  279         if (m != NULL) {
  280                 if (m->m_flags & M_BCAST) {
  281                         /* broadcast */
  282                         (void)memcpy(desten,
  283                             ifp->if_broadcastaddr, ifp->if_addrlen);
  284                         return (0);
  285                 }
  286                 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
  287                         /* multicast */
  288                         ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
  289                         return (0);
  290                 }
  291         }
  292         /* XXXXX
  293          */
  294 retry:
  295         IF_AFDATA_RLOCK(ifp);   
  296         la = lla_lookup(LLTABLE(ifp), flags, dst);
  297         IF_AFDATA_RUNLOCK(ifp); 
  298         if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
  299             && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {          
  300                 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
  301                 IF_AFDATA_WLOCK(ifp);   
  302                 la = lla_lookup(LLTABLE(ifp), flags, dst);
  303                 IF_AFDATA_WUNLOCK(ifp); 
  304         }
  305         if (la == NULL) {
  306                 if (flags & LLE_CREATE)
  307                         log(LOG_DEBUG,
  308                             "arpresolve: can't allocate llinfo for %s\n",
  309                             inet_ntoa(SIN(dst)->sin_addr));
  310                 m_freem(m);
  311                 return (EINVAL);
  312         } 
  313 
  314         if ((la->la_flags & LLE_VALID) &&
  315             ((la->la_flags & LLE_STATIC) || la->la_expire > time_second)) {
  316                 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
  317                 /*
  318                  * If entry has an expiry time and it is approaching,
  319                  * see if we need to send an ARP request within this
  320                  * arpt_down interval.
  321                  */
  322                 if (!(la->la_flags & LLE_STATIC) &&
  323                     time_second + la->la_preempt > la->la_expire) {
  324                         arprequest(ifp, NULL,
  325                             &SIN(dst)->sin_addr, IF_LLADDR(ifp));
  326 
  327                         la->la_preempt--;
  328                 }
  329                 
  330                 *lle = la;
  331                 error = 0;
  332                 goto done;
  333         } 
  334                             
  335         if (la->la_flags & LLE_STATIC) {   /* should not happen! */
  336                 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
  337                     inet_ntoa(SIN(dst)->sin_addr));
  338                 m_freem(m);
  339                 error = EINVAL;
  340                 goto done;
  341         }
  342 
  343         renew = (la->la_asked == 0 || la->la_expire != time_second);
  344         if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
  345                 flags |= LLE_EXCLUSIVE;
  346                 LLE_RUNLOCK(la);
  347                 goto retry;
  348         }
  349         /*
  350          * There is an arptab entry, but no ethernet address
  351          * response yet.  Replace the held mbuf with this
  352          * latest one.
  353          */
  354         if (m != NULL) {
  355                 if (la->la_hold != NULL) {
  356                         m_freem(la->la_hold);
  357                         ARPSTAT_INC(dropped);
  358                 }
  359                 la->la_hold = m;
  360                 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
  361                         flags &= ~LLE_EXCLUSIVE;
  362                         LLE_DOWNGRADE(la);
  363                 }
  364                 
  365         }
  366         /*
  367          * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
  368          * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
  369          * if we have already sent arp_maxtries ARP requests. Retransmit the
  370          * ARP request, but not faster than one request per second.
  371          */
  372         if (la->la_asked < V_arp_maxtries)
  373                 error = EWOULDBLOCK;    /* First request. */
  374         else
  375                 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ?
  376                     EHOSTUNREACH : EHOSTDOWN;
  377 
  378         if (renew) {
  379                 int canceled;
  380 
  381                 LLE_ADDREF(la);
  382                 la->la_expire = time_second;
  383                 canceled = callout_reset(&la->la_timer, hz * V_arpt_down,
  384                     arptimer, la);
  385                 if (canceled)
  386                         LLE_REMREF(la);
  387                 la->la_asked++;
  388                 LLE_WUNLOCK(la);
  389                 arprequest(ifp, NULL, &SIN(dst)->sin_addr,
  390                     IF_LLADDR(ifp));
  391                 return (error);
  392         }
  393 done:
  394         if (flags & LLE_EXCLUSIVE)
  395                 LLE_WUNLOCK(la);
  396         else
  397                 LLE_RUNLOCK(la);
  398         return (error);
  399 }
  400 
  401 /*
  402  * Common length and type checks are done here,
  403  * then the protocol-specific routine is called.
  404  */
  405 static void
  406 arpintr(struct mbuf *m)
  407 {
  408         struct arphdr *ar;
  409 
  410         if (m->m_len < sizeof(struct arphdr) &&
  411             ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
  412                 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
  413                 return;
  414         }
  415         ar = mtod(m, struct arphdr *);
  416 
  417         if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
  418             ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
  419             ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
  420             ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
  421                 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
  422                     (unsigned char *)&ar->ar_hrd, "");
  423                 m_freem(m);
  424                 return;
  425         }
  426 
  427         if (m->m_len < arphdr_len(ar)) {
  428                 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
  429                         log(LOG_ERR, "arp: runt packet\n");
  430                         m_freem(m);
  431                         return;
  432                 }
  433                 ar = mtod(m, struct arphdr *);
  434         }
  435 
  436         ARPSTAT_INC(received);
  437         switch (ntohs(ar->ar_pro)) {
  438 #ifdef INET
  439         case ETHERTYPE_IP:
  440                 in_arpinput(m);
  441                 return;
  442 #endif
  443         }
  444         m_freem(m);
  445 }
  446 
  447 #ifdef INET
  448 /*
  449  * ARP for Internet protocols on 10 Mb/s Ethernet.
  450  * Algorithm is that given in RFC 826.
  451  * In addition, a sanity check is performed on the sender
  452  * protocol address, to catch impersonators.
  453  * We no longer handle negotiations for use of trailer protocol:
  454  * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
  455  * along with IP replies if we wanted trailers sent to us,
  456  * and also sent them in response to IP replies.
  457  * This allowed either end to announce the desire to receive
  458  * trailer packets.
  459  * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
  460  * but formerly didn't normally send requests.
  461  */
  462 static int log_arp_wrong_iface = 1;
  463 static int log_arp_movements = 1;
  464 static int log_arp_permanent_modify = 1;
  465 
  466 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
  467         &log_arp_wrong_iface, 0,
  468         "log arp packets arriving on the wrong interface");
  469 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
  470         &log_arp_movements, 0,
  471         "log arp replies from MACs different than the one in the cache");
  472 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
  473         &log_arp_permanent_modify, 0,
  474         "log arp replies from MACs different than the one in the permanent arp entry");
  475 
  476 
  477 static void
  478 in_arpinput(struct mbuf *m)
  479 {
  480         struct arphdr *ah;
  481         struct ifnet *ifp = m->m_pkthdr.rcvif;
  482         struct llentry *la = NULL;
  483         struct rtentry *rt;
  484         struct ifaddr *ifa;
  485         struct in_ifaddr *ia;
  486         struct mbuf *hold;
  487         struct sockaddr sa;
  488         struct in_addr isaddr, itaddr, myaddr;
  489         u_int8_t *enaddr = NULL;
  490         int op, flags;
  491         int req_len;
  492         int bridged = 0, is_bridge = 0;
  493         int carp_match = 0;
  494         struct sockaddr_in sin;
  495         sin.sin_len = sizeof(struct sockaddr_in);
  496         sin.sin_family = AF_INET;
  497         sin.sin_addr.s_addr = 0;
  498 
  499         if (ifp->if_bridge)
  500                 bridged = 1;
  501         if (ifp->if_type == IFT_BRIDGE)
  502                 is_bridge = 1;
  503 
  504         req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
  505         if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
  506                 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
  507                 return;
  508         }
  509 
  510         ah = mtod(m, struct arphdr *);
  511         op = ntohs(ah->ar_op);
  512         (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
  513         (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
  514 
  515         if (op == ARPOP_REPLY)
  516                 ARPSTAT_INC(rxreplies);
  517 
  518         /*
  519          * For a bridge, we want to check the address irrespective
  520          * of the receive interface. (This will change slightly
  521          * when we have clusters of interfaces).
  522          * If the interface does not match, but the recieving interface
  523          * is part of carp, we call carp_iamatch to see if this is a
  524          * request for the virtual host ip.
  525          * XXX: This is really ugly!
  526          */
  527         IN_IFADDR_RLOCK();
  528         LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  529                 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
  530                     ia->ia_ifp == ifp) &&
  531                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  532                         ifa_ref(&ia->ia_ifa);
  533                         IN_IFADDR_RUNLOCK();
  534                         goto match;
  535                 }
  536                 if (ifp->if_carp != NULL &&
  537                     (*carp_iamatch_p)(ifp, ia, &isaddr, &enaddr) &&
  538                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  539                         carp_match = 1;
  540                         ifa_ref(&ia->ia_ifa);
  541                         IN_IFADDR_RUNLOCK();
  542                         goto match;
  543                 }
  544         }
  545         LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
  546                 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
  547                     ia->ia_ifp == ifp) &&
  548                     isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  549                         ifa_ref(&ia->ia_ifa);
  550                         IN_IFADDR_RUNLOCK();
  551                         goto match;
  552                 }
  553 
  554 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia)                           \
  555   (ia->ia_ifp->if_bridge == ifp->if_softc &&                            \
  556   !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) &&      \
  557   addr == ia->ia_addr.sin_addr.s_addr)
  558         /*
  559          * Check the case when bridge shares its MAC address with
  560          * some of its children, so packets are claimed by bridge
  561          * itself (bridge_input() does it first), but they are really
  562          * meant to be destined to the bridge member.
  563          */
  564         if (is_bridge) {
  565                 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  566                         if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
  567                                 ifa_ref(&ia->ia_ifa);
  568                                 ifp = ia->ia_ifp;
  569                                 IN_IFADDR_RUNLOCK();
  570                                 goto match;
  571                         }
  572                 }
  573         }
  574 #undef BDG_MEMBER_MATCHES_ARP
  575         IN_IFADDR_RUNLOCK();
  576 
  577         /*
  578          * No match, use the first inet address on the receive interface
  579          * as a dummy address for the rest of the function.
  580          */
  581         IF_ADDR_LOCK(ifp);
  582         TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
  583                 if (ifa->ifa_addr->sa_family == AF_INET) {
  584                         ia = ifatoia(ifa);
  585                         ifa_ref(ifa);
  586                         IF_ADDR_UNLOCK(ifp);
  587                         goto match;
  588                 }
  589         IF_ADDR_UNLOCK(ifp);
  590 
  591         /*
  592          * If bridging, fall back to using any inet address.
  593          */
  594         IN_IFADDR_RLOCK();
  595         if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
  596                 IN_IFADDR_RUNLOCK();
  597                 goto drop;
  598         }
  599         ifa_ref(&ia->ia_ifa);
  600         IN_IFADDR_RUNLOCK();
  601 match:
  602         if (!enaddr)
  603                 enaddr = (u_int8_t *)IF_LLADDR(ifp);
  604         myaddr = ia->ia_addr.sin_addr;
  605         ifa_free(&ia->ia_ifa);
  606         if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
  607                 goto drop;      /* it's from me, ignore it. */
  608         if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
  609                 log(LOG_ERR,
  610                     "arp: link address is broadcast for IP address %s!\n",
  611                     inet_ntoa(isaddr));
  612                 goto drop;
  613         }
  614         /*
  615          * Warn if another host is using the same IP address, but only if the
  616          * IP address isn't 0.0.0.0, which is used for DHCP only, in which
  617          * case we suppress the warning to avoid false positive complaints of
  618          * potential misconfiguration.
  619          */
  620         if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
  621                 log(LOG_ERR,
  622                    "arp: %*D is using my IP address %s on %s!\n",
  623                    ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  624                    inet_ntoa(isaddr), ifp->if_xname);
  625                 itaddr = myaddr;
  626                 ARPSTAT_INC(dupips);
  627                 goto reply;
  628         }
  629         if (ifp->if_flags & IFF_STATICARP)
  630                 goto reply;
  631 
  632         bzero(&sin, sizeof(sin));
  633         sin.sin_len = sizeof(struct sockaddr_in);
  634         sin.sin_family = AF_INET;
  635         sin.sin_addr = isaddr;
  636         flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
  637         flags |= LLE_EXCLUSIVE;
  638         IF_AFDATA_LOCK(ifp); 
  639         la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
  640         IF_AFDATA_UNLOCK(ifp);
  641         if (la != NULL) {
  642                 /* the following is not an error when doing bridging */
  643                 if (!bridged && la->lle_tbl->llt_ifp != ifp && !carp_match) {
  644                         if (log_arp_wrong_iface)
  645                                 log(LOG_ERR, "arp: %s is on %s "
  646                                     "but got reply from %*D on %s\n",
  647                                     inet_ntoa(isaddr),
  648                                     la->lle_tbl->llt_ifp->if_xname,
  649                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  650                                     ifp->if_xname);
  651                         LLE_WUNLOCK(la);
  652                         goto reply;
  653                 }
  654                 if ((la->la_flags & LLE_VALID) &&
  655                     bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
  656                         if (la->la_flags & LLE_STATIC) {
  657                                 LLE_WUNLOCK(la);
  658                                 log(LOG_ERR,
  659                                     "arp: %*D attempts to modify permanent "
  660                                     "entry for %s on %s\n",
  661                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  662                                     inet_ntoa(isaddr), ifp->if_xname);
  663                                 goto reply;
  664                         }
  665                         if (log_arp_movements) {
  666                                 log(LOG_INFO, "arp: %s moved from %*D "
  667                                     "to %*D on %s\n",
  668                                     inet_ntoa(isaddr),
  669                                     ifp->if_addrlen,
  670                                     (u_char *)&la->ll_addr, ":",
  671                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  672                                     ifp->if_xname);
  673                         }
  674                 }
  675                     
  676                 if (ifp->if_addrlen != ah->ar_hln) {
  677                         LLE_WUNLOCK(la);
  678                         log(LOG_WARNING,
  679                             "arp from %*D: addr len: new %d, i/f %d (ignored)",
  680                             ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
  681                             ah->ar_hln, ifp->if_addrlen);
  682                         goto reply;
  683                 }
  684                 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
  685                 la->la_flags |= LLE_VALID;
  686 
  687                 if (!(la->la_flags & LLE_STATIC)) {
  688                         int canceled;
  689 
  690                         LLE_ADDREF(la);
  691                         la->la_expire = time_second + V_arpt_keep;
  692                         canceled = callout_reset(&la->la_timer,
  693                             hz * V_arpt_keep, arptimer, la);
  694                         if (canceled)
  695                                 LLE_REMREF(la);
  696                 }
  697                 la->la_asked = 0;
  698                 la->la_preempt = V_arp_maxtries;
  699                 hold = la->la_hold;
  700                 if (hold != NULL) {
  701                         la->la_hold = NULL;
  702                         memcpy(&sa, L3_ADDR(la), sizeof(sa));
  703                 }
  704                 LLE_WUNLOCK(la);
  705                 if (hold != NULL)
  706                         (*ifp->if_output)(ifp, hold, &sa, NULL);
  707         }
  708 reply:
  709         if (op != ARPOP_REQUEST)
  710                 goto drop;
  711         ARPSTAT_INC(rxrequests);
  712 
  713         if (itaddr.s_addr == myaddr.s_addr) {
  714                 /* Shortcut.. the receiving interface is the target. */
  715                 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  716                 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  717         } else {
  718                 struct llentry *lle = NULL;
  719 
  720                 sin.sin_addr = itaddr;
  721                 IF_AFDATA_LOCK(ifp); 
  722                 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
  723                 IF_AFDATA_UNLOCK(ifp);
  724 
  725                 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
  726                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  727                         (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
  728                         LLE_RUNLOCK(lle);
  729                 } else {
  730 
  731                         if (lle != NULL)
  732                                 LLE_RUNLOCK(lle);
  733 
  734                         if (!V_arp_proxyall)
  735                                 goto drop;
  736                         
  737                         sin.sin_addr = itaddr;
  738                         /* XXX MRT use table 0 for arp reply  */
  739                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  740                         if (!rt)
  741                                 goto drop;
  742 
  743                         /*
  744                          * Don't send proxies for nodes on the same interface
  745                          * as this one came out of, or we'll get into a fight
  746                          * over who claims what Ether address.
  747                          */
  748                         if (!rt->rt_ifp || rt->rt_ifp == ifp) {
  749                                 RTFREE_LOCKED(rt);
  750                                 goto drop;
  751                         }
  752                         RTFREE_LOCKED(rt);
  753 
  754                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  755                         (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  756 
  757                         /*
  758                          * Also check that the node which sent the ARP packet
  759                          * is on the the interface we expect it to be on. This
  760                          * avoids ARP chaos if an interface is connected to the
  761                          * wrong network.
  762                          */
  763                         sin.sin_addr = isaddr;
  764                         
  765                         /* XXX MRT use table 0 for arp checks */
  766                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  767                         if (!rt)
  768                                 goto drop;
  769                         if (rt->rt_ifp != ifp) {
  770                                 log(LOG_INFO, "arp_proxy: ignoring request"
  771                                     " from %s via %s, expecting %s\n",
  772                                     inet_ntoa(isaddr), ifp->if_xname,
  773                                     rt->rt_ifp->if_xname);
  774                                 RTFREE_LOCKED(rt);
  775                                 goto drop;
  776                         }
  777                         RTFREE_LOCKED(rt);
  778 
  779 #ifdef DEBUG_PROXY
  780                         printf("arp: proxying for %s\n",
  781                                inet_ntoa(itaddr));
  782 #endif
  783                 }
  784         }
  785 
  786         if (itaddr.s_addr == myaddr.s_addr &&
  787             IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
  788                 /* RFC 3927 link-local IPv4; always reply by broadcast. */
  789 #ifdef DEBUG_LINKLOCAL
  790                 printf("arp: sending reply for link-local addr %s\n",
  791                     inet_ntoa(itaddr));
  792 #endif
  793                 m->m_flags |= M_BCAST;
  794                 m->m_flags &= ~M_MCAST;
  795         } else {
  796                 /* default behaviour; never reply by broadcast. */
  797                 m->m_flags &= ~(M_BCAST|M_MCAST);
  798         }
  799         (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
  800         (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
  801         ah->ar_op = htons(ARPOP_REPLY);
  802         ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
  803         m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);   
  804         m->m_pkthdr.len = m->m_len;   
  805         sa.sa_family = AF_ARP;
  806         sa.sa_len = 2;
  807         (*ifp->if_output)(ifp, m, &sa, NULL);
  808         ARPSTAT_INC(txreplies);
  809         return;
  810 
  811 drop:
  812         m_freem(m);
  813 }
  814 #endif
  815 
  816 void
  817 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
  818 {
  819         struct llentry *lle;
  820 
  821         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
  822                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
  823                                 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
  824                 /* 
  825                  * interface address is considered static entry
  826                  * because the output of the arp utility shows
  827                  * that L2 entry as permanent
  828                  */
  829                 IF_AFDATA_LOCK(ifp);
  830                 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
  831                                  (struct sockaddr *)IA_SIN(ifa));
  832                 IF_AFDATA_UNLOCK(ifp);
  833                 if (lle == NULL)
  834                         log(LOG_INFO, "arp_ifinit: cannot create arp "
  835                             "entry for interface address\n");
  836                 else
  837                         LLE_RUNLOCK(lle);
  838         }
  839         ifa->ifa_rtrequest = NULL;
  840 }
  841 
  842 void
  843 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
  844 {
  845         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
  846                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
  847                                 &IA_SIN(ifa)->sin_addr, enaddr);
  848         ifa->ifa_rtrequest = NULL;
  849 }
  850 
  851 static void
  852 arp_init(void)
  853 {
  854 
  855         netisr_register(&arp_nh);
  856 }
  857 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);

Cache object: c02baa3300fd449b8f2d40fd85311a47


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