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/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/8.4/sys/netinet/if_ether.c 233201 2012-03-19 20:49:42Z jhb $");
   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)
   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 VNET_DEFINE(struct arpstat, arpstat);  /* ARP statistics, see if_arp.h */
   93 
   94 static VNET_DEFINE(int, arp_maxhold) = 1;
   95 
   96 #define V_arpt_keep             VNET(arpt_keep)
   97 #define V_arpt_down             VNET(arpt_down)
   98 #define V_arp_maxtries          VNET(arp_maxtries)
   99 #define V_arp_proxyall          VNET(arp_proxyall)
  100 #define V_arpstat               VNET(arpstat)
  101 #define V_arp_maxhold           VNET(arp_maxhold)
  102 
  103 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
  104         &VNET_NAME(arpt_keep), 0,
  105         "ARP entry lifetime in seconds");
  106 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
  107         &VNET_NAME(arp_maxtries), 0,
  108         "ARP resolution attempts before returning error");
  109 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
  110         &VNET_NAME(useloopback), 0,
  111         "Use the loopback interface for local traffic");
  112 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
  113         &VNET_NAME(arp_proxyall), 0,
  114         "Enable proxy ARP for all suitable requests");
  115 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_RW,
  116         &VNET_NAME(arpt_down), 0,
  117         "Incomplete ARP entry lifetime in seconds");
  118 SYSCTL_VNET_STRUCT(_net_link_ether_arp, OID_AUTO, stats, CTLFLAG_RW,
  119         &VNET_NAME(arpstat), arpstat,
  120         "ARP statistics (struct arpstat, net/if_arp.h)");
  121 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_RW,
  122         &VNET_NAME(arp_maxhold), 0, 
  123         "Number of packets to hold per ARP entry");
  124 
  125 static void     arp_init(void);
  126 void            arprequest(struct ifnet *,
  127                         struct in_addr *, struct in_addr *, u_char *);
  128 static void     arpintr(struct mbuf *);
  129 static void     arptimer(void *);
  130 #ifdef INET
  131 static void     in_arpinput(struct mbuf *);
  132 #endif
  133 
  134 static const struct netisr_handler arp_nh = {
  135         .nh_name = "arp",
  136         .nh_handler = arpintr,
  137         .nh_proto = NETISR_ARP,
  138         .nh_policy = NETISR_POLICY_SOURCE,
  139 };
  140 
  141 #ifdef AF_INET
  142 void arp_ifscrub(struct ifnet *ifp, uint32_t addr);
  143 
  144 /*
  145  * called by in_ifscrub to remove entry from the table when
  146  * the interface goes away
  147  */
  148 void
  149 arp_ifscrub(struct ifnet *ifp, uint32_t addr)
  150 {
  151         struct sockaddr_in addr4;
  152 
  153         bzero((void *)&addr4, sizeof(addr4));
  154         addr4.sin_len    = sizeof(addr4);
  155         addr4.sin_family = AF_INET;
  156         addr4.sin_addr.s_addr = addr;
  157         IF_AFDATA_LOCK(ifp);
  158         lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
  159             (struct sockaddr *)&addr4);
  160         IF_AFDATA_UNLOCK(ifp);
  161 }
  162 #endif
  163 
  164 /*
  165  * Timeout routine.  Age arp_tab entries periodically.
  166  */
  167 static void
  168 arptimer(void *arg)
  169 {
  170         struct ifnet *ifp;
  171         struct llentry   *lle;
  172         int pkts_dropped;
  173 
  174         KASSERT(arg != NULL, ("%s: arg NULL", __func__));
  175         lle = (struct llentry *)arg;
  176         ifp = lle->lle_tbl->llt_ifp;
  177         CURVNET_SET(ifp->if_vnet);
  178         IF_AFDATA_LOCK(ifp);
  179         LLE_WLOCK(lle);
  180         if (lle->la_flags & LLE_STATIC)
  181                 LLE_WUNLOCK(lle);
  182         else {
  183                 if (!callout_pending(&lle->la_timer) &&
  184                     callout_active(&lle->la_timer)) {
  185                         callout_stop(&lle->la_timer);
  186                         LLE_REMREF(lle);
  187                         pkts_dropped = llentry_free(lle);
  188                         ARPSTAT_ADD(dropped, pkts_dropped);
  189                         ARPSTAT_INC(timeouts);
  190                 } else {
  191 #ifdef DIAGNOSTIC
  192                         struct sockaddr *l3addr = L3_ADDR(lle);
  193                         log(LOG_INFO, 
  194                             "arptimer issue: %p, IPv4 address: \"%s\"\n", lle,
  195                             inet_ntoa(
  196                                 ((const struct sockaddr_in *)l3addr)->sin_addr));
  197 #endif
  198                         LLE_WUNLOCK(lle);
  199                 }
  200         }
  201         IF_AFDATA_UNLOCK(ifp);
  202         CURVNET_RESTORE();
  203 }
  204 
  205 /*
  206  * Broadcast an ARP request. Caller specifies:
  207  *      - arp header source ip address
  208  *      - arp header target ip address
  209  *      - arp header source ethernet address
  210  */
  211 void
  212 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr  *tip,
  213     u_char *enaddr)
  214 {
  215         struct mbuf *m;
  216         struct arphdr *ah;
  217         struct sockaddr sa;
  218 
  219         if (sip == NULL) {
  220                 /* XXX don't believe this can happen (or explain why) */
  221                 /*
  222                  * The caller did not supply a source address, try to find
  223                  * a compatible one among those assigned to this interface.
  224                  */
  225                 struct ifaddr *ifa;
  226 
  227                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  228                         if (!ifa->ifa_addr ||
  229                             ifa->ifa_addr->sa_family != AF_INET)
  230                                 continue;
  231                         sip = &SIN(ifa->ifa_addr)->sin_addr;
  232                         if (0 == ((sip->s_addr ^ tip->s_addr) &
  233                             SIN(ifa->ifa_netmask)->sin_addr.s_addr) )
  234                                 break;  /* found it. */
  235                 }
  236                 if (sip == NULL) {  
  237                         printf("%s: cannot find matching address\n", __func__);
  238                         return;
  239                 }
  240         }
  241 
  242         if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
  243                 return;
  244         m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
  245                 2*ifp->if_data.ifi_addrlen;
  246         m->m_pkthdr.len = m->m_len;
  247         MH_ALIGN(m, m->m_len);
  248         ah = mtod(m, struct arphdr *);
  249         bzero((caddr_t)ah, m->m_len);
  250 #ifdef MAC
  251         mac_netinet_arp_send(ifp, m);
  252 #endif
  253         ah->ar_pro = htons(ETHERTYPE_IP);
  254         ah->ar_hln = ifp->if_addrlen;           /* hardware address length */
  255         ah->ar_pln = sizeof(struct in_addr);    /* protocol address length */
  256         ah->ar_op = htons(ARPOP_REQUEST);
  257         bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
  258         bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
  259         bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
  260         sa.sa_family = AF_ARP;
  261         sa.sa_len = 2;
  262         m->m_flags |= M_BCAST;
  263         (*ifp->if_output)(ifp, m, &sa, NULL);
  264         ARPSTAT_INC(txrequests);
  265 }
  266 
  267 /*
  268  * Resolve an IP address into an ethernet address.
  269  * On input:
  270  *    ifp is the interface we use
  271  *    rt0 is the route to the final destination (possibly useless)
  272  *    m is the mbuf. May be NULL if we don't have a packet.
  273  *    dst is the next hop,
  274  *    desten is where we want the address.
  275  *
  276  * On success, desten is filled in and the function returns 0;
  277  * If the packet must be held pending resolution, we return EWOULDBLOCK
  278  * On other errors, we return the corresponding error code.
  279  * Note that m_freem() handles NULL.
  280  */
  281 int
  282 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
  283         struct sockaddr *dst, u_char *desten, struct llentry **lle)
  284 {
  285         struct llentry *la = 0;
  286         u_int flags = 0;
  287         struct mbuf *curr = NULL;
  288         struct mbuf *next = NULL;
  289         int error, renew;
  290 
  291         *lle = NULL;
  292         if (m != NULL) {
  293                 if (m->m_flags & M_BCAST) {
  294                         /* broadcast */
  295                         (void)memcpy(desten,
  296                             ifp->if_broadcastaddr, ifp->if_addrlen);
  297                         return (0);
  298                 }
  299                 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
  300                         /* multicast */
  301                         ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
  302                         return (0);
  303                 }
  304         }
  305         /* XXXXX
  306          */
  307 retry:
  308         IF_AFDATA_RLOCK(ifp);   
  309         la = lla_lookup(LLTABLE(ifp), flags, dst);
  310         IF_AFDATA_RUNLOCK(ifp); 
  311         if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
  312             && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {          
  313                 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
  314                 IF_AFDATA_WLOCK(ifp);   
  315                 la = lla_lookup(LLTABLE(ifp), flags, dst);
  316                 IF_AFDATA_WUNLOCK(ifp); 
  317         }
  318         if (la == NULL) {
  319                 if (flags & LLE_CREATE)
  320                         log(LOG_DEBUG,
  321                             "arpresolve: can't allocate llinfo for %s\n",
  322                             inet_ntoa(SIN(dst)->sin_addr));
  323                 m_freem(m);
  324                 return (EINVAL);
  325         } 
  326 
  327         if ((la->la_flags & LLE_VALID) &&
  328             ((la->la_flags & LLE_STATIC) || la->la_expire > time_second)) {
  329                 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
  330                 /*
  331                  * If entry has an expiry time and it is approaching,
  332                  * see if we need to send an ARP request within this
  333                  * arpt_down interval.
  334                  */
  335                 if (!(la->la_flags & LLE_STATIC) &&
  336                     time_second + la->la_preempt > la->la_expire) {
  337                         arprequest(ifp, NULL,
  338                             &SIN(dst)->sin_addr, IF_LLADDR(ifp));
  339 
  340                         la->la_preempt--;
  341                 }
  342                 
  343                 *lle = la;
  344                 error = 0;
  345                 goto done;
  346         } 
  347                             
  348         if (la->la_flags & LLE_STATIC) {   /* should not happen! */
  349                 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
  350                     inet_ntoa(SIN(dst)->sin_addr));
  351                 m_freem(m);
  352                 error = EINVAL;
  353                 goto done;
  354         }
  355 
  356         renew = (la->la_asked == 0 || la->la_expire != time_second);
  357         if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
  358                 flags |= LLE_EXCLUSIVE;
  359                 LLE_RUNLOCK(la);
  360                 goto retry;
  361         }
  362         /*
  363          * There is an arptab entry, but no ethernet address
  364          * response yet.  Add the mbuf to the list, dropping
  365          * the oldest packet if we have exceeded the system
  366          * setting.
  367          */
  368         if (m != NULL) {
  369                 if (la->la_numheld >= V_arp_maxhold) {
  370                         if (la->la_hold != NULL) {
  371                                 next = la->la_hold->m_nextpkt;
  372                                 m_freem(la->la_hold);
  373                                 la->la_hold = next;
  374                                 la->la_numheld--;
  375                                 ARPSTAT_INC(dropped);
  376                         }
  377                 } 
  378                 if (la->la_hold != NULL) {
  379                         curr = la->la_hold;
  380                         while (curr->m_nextpkt != NULL)
  381                                 curr = curr->m_nextpkt;
  382                         curr->m_nextpkt = m;
  383                 } else 
  384                         la->la_hold = m;
  385                 la->la_numheld++;
  386                 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
  387                         flags &= ~LLE_EXCLUSIVE;
  388                         LLE_DOWNGRADE(la);
  389                 }
  390                 
  391         }
  392         /*
  393          * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
  394          * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
  395          * if we have already sent arp_maxtries ARP requests. Retransmit the
  396          * ARP request, but not faster than one request per second.
  397          */
  398         if (la->la_asked < V_arp_maxtries)
  399                 error = EWOULDBLOCK;    /* First request. */
  400         else
  401                 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ?
  402                     EHOSTUNREACH : EHOSTDOWN;
  403 
  404         if (renew) {
  405                 int canceled;
  406 
  407                 LLE_ADDREF(la);
  408                 la->la_expire = time_second;
  409                 canceled = callout_reset(&la->la_timer, hz * V_arpt_down,
  410                     arptimer, la);
  411                 if (canceled)
  412                         LLE_REMREF(la);
  413                 la->la_asked++;
  414                 LLE_WUNLOCK(la);
  415                 arprequest(ifp, NULL, &SIN(dst)->sin_addr,
  416                     IF_LLADDR(ifp));
  417                 return (error);
  418         }
  419 done:
  420         if (flags & LLE_EXCLUSIVE)
  421                 LLE_WUNLOCK(la);
  422         else
  423                 LLE_RUNLOCK(la);
  424         return (error);
  425 }
  426 
  427 /*
  428  * Common length and type checks are done here,
  429  * then the protocol-specific routine is called.
  430  */
  431 static void
  432 arpintr(struct mbuf *m)
  433 {
  434         struct arphdr *ar;
  435 
  436         if (m->m_len < sizeof(struct arphdr) &&
  437             ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
  438                 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
  439                 return;
  440         }
  441         ar = mtod(m, struct arphdr *);
  442 
  443         if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
  444             ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
  445             ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
  446             ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
  447                 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
  448                     (unsigned char *)&ar->ar_hrd, "");
  449                 m_freem(m);
  450                 return;
  451         }
  452 
  453         if (m->m_len < arphdr_len(ar)) {
  454                 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
  455                         log(LOG_ERR, "arp: runt packet\n");
  456                         m_freem(m);
  457                         return;
  458                 }
  459                 ar = mtod(m, struct arphdr *);
  460         }
  461 
  462         ARPSTAT_INC(received);
  463         switch (ntohs(ar->ar_pro)) {
  464 #ifdef INET
  465         case ETHERTYPE_IP:
  466                 in_arpinput(m);
  467                 return;
  468 #endif
  469         }
  470         m_freem(m);
  471 }
  472 
  473 #ifdef INET
  474 /*
  475  * ARP for Internet protocols on 10 Mb/s Ethernet.
  476  * Algorithm is that given in RFC 826.
  477  * In addition, a sanity check is performed on the sender
  478  * protocol address, to catch impersonators.
  479  * We no longer handle negotiations for use of trailer protocol:
  480  * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
  481  * along with IP replies if we wanted trailers sent to us,
  482  * and also sent them in response to IP replies.
  483  * This allowed either end to announce the desire to receive
  484  * trailer packets.
  485  * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
  486  * but formerly didn't normally send requests.
  487  */
  488 static int log_arp_wrong_iface = 1;
  489 static int log_arp_movements = 1;
  490 static int log_arp_permanent_modify = 1;
  491 
  492 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
  493         &log_arp_wrong_iface, 0,
  494         "log arp packets arriving on the wrong interface");
  495 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
  496         &log_arp_movements, 0,
  497         "log arp replies from MACs different than the one in the cache");
  498 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
  499         &log_arp_permanent_modify, 0,
  500         "log arp replies from MACs different than the one in the permanent arp entry");
  501 
  502 
  503 static void
  504 in_arpinput(struct mbuf *m)
  505 {
  506         struct arphdr *ah;
  507         struct ifnet *ifp = m->m_pkthdr.rcvif;
  508         struct llentry *la = NULL;
  509         struct rtentry *rt;
  510         struct ifaddr *ifa;
  511         struct in_ifaddr *ia;
  512         struct sockaddr sa;
  513         struct in_addr isaddr, itaddr, myaddr;
  514         u_int8_t *enaddr = NULL;
  515         int op, flags;
  516         int req_len;
  517         int bridged = 0, is_bridge = 0;
  518         int carp_match = 0;
  519         struct sockaddr_in sin;
  520         sin.sin_len = sizeof(struct sockaddr_in);
  521         sin.sin_family = AF_INET;
  522         sin.sin_addr.s_addr = 0;
  523 
  524         if (ifp->if_bridge)
  525                 bridged = 1;
  526         if (ifp->if_type == IFT_BRIDGE)
  527                 is_bridge = 1;
  528 
  529         req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
  530         if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
  531                 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
  532                 return;
  533         }
  534 
  535         ah = mtod(m, struct arphdr *);
  536         op = ntohs(ah->ar_op);
  537         (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
  538         (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
  539 
  540         if (op == ARPOP_REPLY)
  541                 ARPSTAT_INC(rxreplies);
  542 
  543         /*
  544          * For a bridge, we want to check the address irrespective
  545          * of the receive interface. (This will change slightly
  546          * when we have clusters of interfaces).
  547          * If the interface does not match, but the recieving interface
  548          * is part of carp, we call carp_iamatch to see if this is a
  549          * request for the virtual host ip.
  550          * XXX: This is really ugly!
  551          */
  552         IN_IFADDR_RLOCK();
  553         LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  554                 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
  555                     ia->ia_ifp == ifp) &&
  556                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  557                         ifa_ref(&ia->ia_ifa);
  558                         IN_IFADDR_RUNLOCK();
  559                         goto match;
  560                 }
  561                 if (ifp->if_carp != NULL &&
  562                     (*carp_iamatch_p)(ifp, ia, &isaddr, &enaddr) &&
  563                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  564                         carp_match = 1;
  565                         ifa_ref(&ia->ia_ifa);
  566                         IN_IFADDR_RUNLOCK();
  567                         goto match;
  568                 }
  569         }
  570         LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
  571                 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
  572                     ia->ia_ifp == ifp) &&
  573                     isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  574                         ifa_ref(&ia->ia_ifa);
  575                         IN_IFADDR_RUNLOCK();
  576                         goto match;
  577                 }
  578 
  579 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia)                           \
  580   (ia->ia_ifp->if_bridge == ifp->if_softc &&                            \
  581   !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) &&      \
  582   addr == ia->ia_addr.sin_addr.s_addr)
  583         /*
  584          * Check the case when bridge shares its MAC address with
  585          * some of its children, so packets are claimed by bridge
  586          * itself (bridge_input() does it first), but they are really
  587          * meant to be destined to the bridge member.
  588          */
  589         if (is_bridge) {
  590                 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  591                         if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
  592                                 ifa_ref(&ia->ia_ifa);
  593                                 ifp = ia->ia_ifp;
  594                                 IN_IFADDR_RUNLOCK();
  595                                 goto match;
  596                         }
  597                 }
  598         }
  599 #undef BDG_MEMBER_MATCHES_ARP
  600         IN_IFADDR_RUNLOCK();
  601 
  602         /*
  603          * No match, use the first inet address on the receive interface
  604          * as a dummy address for the rest of the function.
  605          */
  606         IF_ADDR_RLOCK(ifp);
  607         TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
  608                 if (ifa->ifa_addr->sa_family == AF_INET) {
  609                         ia = ifatoia(ifa);
  610                         ifa_ref(ifa);
  611                         IF_ADDR_RUNLOCK(ifp);
  612                         goto match;
  613                 }
  614         IF_ADDR_RUNLOCK(ifp);
  615 
  616         /*
  617          * If bridging, fall back to using any inet address.
  618          */
  619         IN_IFADDR_RLOCK();
  620         if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
  621                 IN_IFADDR_RUNLOCK();
  622                 goto drop;
  623         }
  624         ifa_ref(&ia->ia_ifa);
  625         IN_IFADDR_RUNLOCK();
  626 match:
  627         if (!enaddr)
  628                 enaddr = (u_int8_t *)IF_LLADDR(ifp);
  629         myaddr = ia->ia_addr.sin_addr;
  630         ifa_free(&ia->ia_ifa);
  631         if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
  632                 goto drop;      /* it's from me, ignore it. */
  633         if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
  634                 log(LOG_ERR,
  635                     "arp: link address is broadcast for IP address %s!\n",
  636                     inet_ntoa(isaddr));
  637                 goto drop;
  638         }
  639         /*
  640          * Warn if another host is using the same IP address, but only if the
  641          * IP address isn't 0.0.0.0, which is used for DHCP only, in which
  642          * case we suppress the warning to avoid false positive complaints of
  643          * potential misconfiguration.
  644          */
  645         if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
  646                 log(LOG_ERR,
  647                    "arp: %*D is using my IP address %s on %s!\n",
  648                    ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  649                    inet_ntoa(isaddr), ifp->if_xname);
  650                 itaddr = myaddr;
  651                 ARPSTAT_INC(dupips);
  652                 goto reply;
  653         }
  654         if (ifp->if_flags & IFF_STATICARP)
  655                 goto reply;
  656 
  657         bzero(&sin, sizeof(sin));
  658         sin.sin_len = sizeof(struct sockaddr_in);
  659         sin.sin_family = AF_INET;
  660         sin.sin_addr = isaddr;
  661         flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
  662         flags |= LLE_EXCLUSIVE;
  663         IF_AFDATA_LOCK(ifp); 
  664         la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
  665         IF_AFDATA_UNLOCK(ifp);
  666         if (la != NULL) {
  667                 /* the following is not an error when doing bridging */
  668                 if (!bridged && la->lle_tbl->llt_ifp != ifp && !carp_match) {
  669                         if (log_arp_wrong_iface)
  670                                 log(LOG_ERR, "arp: %s is on %s "
  671                                     "but got reply from %*D on %s\n",
  672                                     inet_ntoa(isaddr),
  673                                     la->lle_tbl->llt_ifp->if_xname,
  674                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  675                                     ifp->if_xname);
  676                         LLE_WUNLOCK(la);
  677                         goto reply;
  678                 }
  679                 if ((la->la_flags & LLE_VALID) &&
  680                     bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
  681                         if (la->la_flags & LLE_STATIC) {
  682                                 LLE_WUNLOCK(la);
  683                                 if (log_arp_permanent_modify)
  684                                         log(LOG_ERR,
  685                                             "arp: %*D attempts to modify "
  686                                             "permanent entry for %s on %s\n",
  687                                             ifp->if_addrlen,
  688                                             (u_char *)ar_sha(ah), ":",
  689                                             inet_ntoa(isaddr), ifp->if_xname);
  690                                 goto reply;
  691                         }
  692                         if (log_arp_movements) {
  693                                 log(LOG_INFO, "arp: %s moved from %*D "
  694                                     "to %*D on %s\n",
  695                                     inet_ntoa(isaddr),
  696                                     ifp->if_addrlen,
  697                                     (u_char *)&la->ll_addr, ":",
  698                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  699                                     ifp->if_xname);
  700                         }
  701                 }
  702                     
  703                 if (ifp->if_addrlen != ah->ar_hln) {
  704                         LLE_WUNLOCK(la);
  705                         log(LOG_WARNING,
  706                             "arp from %*D: addr len: new %d, i/f %d (ignored)",
  707                             ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
  708                             ah->ar_hln, ifp->if_addrlen);
  709                         goto reply;
  710                 }
  711                 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
  712                 la->la_flags |= LLE_VALID;
  713 
  714                 if (!(la->la_flags & LLE_STATIC)) {
  715                         int canceled;
  716 
  717                         LLE_ADDREF(la);
  718                         la->la_expire = time_second + V_arpt_keep;
  719                         canceled = callout_reset(&la->la_timer,
  720                             hz * V_arpt_keep, arptimer, la);
  721                         if (canceled)
  722                                 LLE_REMREF(la);
  723                 }
  724                 la->la_asked = 0;
  725                 la->la_preempt = V_arp_maxtries;
  726                 /* 
  727                  * The packets are all freed within the call to the output
  728                  * routine.
  729                  *
  730                  * NB: The lock MUST be released before the call to the
  731                  * output routine.
  732                  */
  733                 if (la->la_hold != NULL) {
  734                         struct mbuf *m_hold, *m_hold_next;
  735 
  736                         m_hold = la->la_hold;
  737                         la->la_hold = NULL;
  738                         la->la_numheld = 0;
  739                         memcpy(&sa, L3_ADDR(la), sizeof(sa));
  740                         LLE_WUNLOCK(la);
  741                         for (; m_hold != NULL; m_hold = m_hold_next) {
  742                                 m_hold_next = m_hold->m_nextpkt;
  743                                 m_hold->m_nextpkt = NULL;
  744                                 (*ifp->if_output)(ifp, m_hold, &sa, NULL);
  745                         }
  746                 } else
  747                         LLE_WUNLOCK(la);
  748         } /* end of FIB loop */
  749 reply:
  750         if (op != ARPOP_REQUEST)
  751                 goto drop;
  752         ARPSTAT_INC(rxrequests);
  753 
  754         if (itaddr.s_addr == myaddr.s_addr) {
  755                 /* Shortcut.. the receiving interface is the target. */
  756                 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  757                 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  758         } else {
  759                 struct llentry *lle = NULL;
  760 
  761                 sin.sin_addr = itaddr;
  762                 IF_AFDATA_LOCK(ifp); 
  763                 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
  764                 IF_AFDATA_UNLOCK(ifp);
  765 
  766                 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
  767                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  768                         (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
  769                         LLE_RUNLOCK(lle);
  770                 } else {
  771 
  772                         if (lle != NULL)
  773                                 LLE_RUNLOCK(lle);
  774 
  775                         if (!V_arp_proxyall)
  776                                 goto drop;
  777                         
  778                         sin.sin_addr = itaddr;
  779                         /* XXX MRT use table 0 for arp reply  */
  780                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  781                         if (!rt)
  782                                 goto drop;
  783 
  784                         /*
  785                          * Don't send proxies for nodes on the same interface
  786                          * as this one came out of, or we'll get into a fight
  787                          * over who claims what Ether address.
  788                          */
  789                         if (!rt->rt_ifp || rt->rt_ifp == ifp) {
  790                                 RTFREE_LOCKED(rt);
  791                                 goto drop;
  792                         }
  793                         RTFREE_LOCKED(rt);
  794 
  795                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  796                         (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  797 
  798                         /*
  799                          * Also check that the node which sent the ARP packet
  800                          * is on the interface we expect it to be on. This
  801                          * avoids ARP chaos if an interface is connected to the
  802                          * wrong network.
  803                          */
  804                         sin.sin_addr = isaddr;
  805                         
  806                         /* XXX MRT use table 0 for arp checks */
  807                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  808                         if (!rt)
  809                                 goto drop;
  810                         if (rt->rt_ifp != ifp) {
  811                                 log(LOG_INFO, "arp_proxy: ignoring request"
  812                                     " from %s via %s, expecting %s\n",
  813                                     inet_ntoa(isaddr), ifp->if_xname,
  814                                     rt->rt_ifp->if_xname);
  815                                 RTFREE_LOCKED(rt);
  816                                 goto drop;
  817                         }
  818                         RTFREE_LOCKED(rt);
  819 
  820 #ifdef DEBUG_PROXY
  821                         printf("arp: proxying for %s\n",
  822                                inet_ntoa(itaddr));
  823 #endif
  824                 }
  825         }
  826 
  827         if (itaddr.s_addr == myaddr.s_addr &&
  828             IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
  829                 /* RFC 3927 link-local IPv4; always reply by broadcast. */
  830 #ifdef DEBUG_LINKLOCAL
  831                 printf("arp: sending reply for link-local addr %s\n",
  832                     inet_ntoa(itaddr));
  833 #endif
  834                 m->m_flags |= M_BCAST;
  835                 m->m_flags &= ~M_MCAST;
  836         } else {
  837                 /* default behaviour; never reply by broadcast. */
  838                 m->m_flags &= ~(M_BCAST|M_MCAST);
  839         }
  840         (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
  841         (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
  842         ah->ar_op = htons(ARPOP_REPLY);
  843         ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
  844         m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);   
  845         m->m_pkthdr.len = m->m_len;   
  846         m->m_pkthdr.rcvif = NULL;
  847         sa.sa_family = AF_ARP;
  848         sa.sa_len = 2;
  849         (*ifp->if_output)(ifp, m, &sa, NULL);
  850         ARPSTAT_INC(txreplies);
  851         return;
  852 
  853 drop:
  854         m_freem(m);
  855 }
  856 #endif
  857 
  858 void
  859 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
  860 {
  861         struct llentry *lle;
  862 
  863         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
  864                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
  865                                 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
  866                 /* 
  867                  * interface address is considered static entry
  868                  * because the output of the arp utility shows
  869                  * that L2 entry as permanent
  870                  */
  871                 IF_AFDATA_LOCK(ifp);
  872                 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
  873                                  (struct sockaddr *)IA_SIN(ifa));
  874                 IF_AFDATA_UNLOCK(ifp);
  875                 if (lle == NULL)
  876                         log(LOG_INFO, "arp_ifinit: cannot create arp "
  877                             "entry for interface address\n");
  878                 else
  879                         LLE_RUNLOCK(lle);
  880         }
  881         ifa->ifa_rtrequest = NULL;
  882 }
  883 
  884 void
  885 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
  886 {
  887         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
  888                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
  889                                 &IA_SIN(ifa)->sin_addr, enaddr);
  890         ifa->ifa_rtrequest = NULL;
  891 }
  892 
  893 static void
  894 arp_init(void)
  895 {
  896 
  897         netisr_register(&arp_nh);
  898 }
  899 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);

Cache object: 43eb91568074f572d58cc5bf78fac6b3


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