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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: src/sys/netinet/if_ether.c,v 1.183 2008/12/02 21:37:28 bz Exp $");
 40 
 41 #include "opt_inet.h"
 42 #include "opt_mac.h"
 43 #include "opt_carp.h"
 44 
 45 #include <sys/param.h>
 46 #include <sys/kernel.h>
 47 #include <sys/queue.h>
 48 #include <sys/sysctl.h>
 49 #include <sys/systm.h>
 50 #include <sys/mbuf.h>
 51 #include <sys/malloc.h>
 52 #include <sys/proc.h>
 53 #include <sys/socket.h>
 54 #include <sys/syslog.h>
 55 #include <sys/vimage.h>
 56 
 57 #include <net/if.h>
 58 #include <net/if_dl.h>
 59 #include <net/if_types.h>
 60 #include <net/route.h>
 61 #include <net/netisr.h>
 62 #include <net/if_llc.h>
 63 #include <net/ethernet.h>
 64 #include <net/vnet.h>
 65 
 66 #include <netinet/in.h>
 67 #include <netinet/in_var.h>
 68 #include <netinet/if_ether.h>
 69 #include <netinet/vinet.h>
 70 
 71 #include <net/if_arc.h>
 72 #include <net/iso88025.h>
 73 
 74 #ifdef DEV_CARP
 75 #include <netinet/ip_carp.h>
 76 #endif
 77 
 78 #include <security/mac/mac_framework.h>
 79 
 80 #define SIN(s) ((struct sockaddr_in *)s)
 81 #define SDL(s) ((struct sockaddr_dl *)s)
 82 
 83 SYSCTL_DECL(_net_link_ether);
 84 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
 85 
 86 /* timer values */
 87 #ifdef VIMAGE_GLOBALS
 88 static int      arpt_keep; /* once resolved, good for 20 more minutes */
 89 static int      arp_maxtries;
 90 static int      useloopback; /* use loopback interface for local traffic */
 91 static int      arp_proxyall;
 92 #endif
 93 
 94 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, max_age,
 95     CTLFLAG_RW, arpt_keep, 0, "ARP entry lifetime in seconds");
 96 
 97 #define rt_expire rt_rmx.rmx_expire
 98 
 99 struct llinfo_arp {
100         struct  callout la_timer;
101         struct  rtentry *la_rt;
102         struct  mbuf *la_hold;  /* last packet until resolved/timeout */
103         u_short la_preempt;     /* countdown for pre-expiry arps */
104         u_short la_asked;       /* # requests sent */
105 };
106 
107 static struct   ifqueue arpintrq;
108 
109 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, maxtries,
110         CTLFLAG_RW, arp_maxtries, 0,
111         "ARP resolution attempts before returning error");
112 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, useloopback,
113         CTLFLAG_RW, useloopback, 0,
114         "Use the loopback interface for local traffic");
115 SYSCTL_V_INT(V_NET, vnet_inet, _net_link_ether_inet, OID_AUTO, proxyall,
116         CTLFLAG_RW, arp_proxyall, 0,
117         "Enable proxy ARP for all suitable requests");
118 
119 static void     arp_init(void);
120 static void     arp_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
121 static void     arprequest(struct ifnet *,
122                         struct in_addr *, struct in_addr *, u_char *);
123 static void     arpintr(struct mbuf *);
124 static void     arptimer(void *);
125 static struct rtentry
126                 *arplookup(u_long, int, int, int);
127 #ifdef INET
128 static void     in_arpinput(struct mbuf *);
129 #endif
130 
131 /*
132  * Timeout routine.
133  */
134 static void
135 arptimer(void *arg)
136 {
137         struct rtentry *rt = (struct rtentry *)arg;
138 
139         RT_LOCK_ASSERT(rt);
140         /*
141          * The lock is needed to close a theoretical race
142          * between spontaneous expiry and intentional removal.
143          * We still got an extra reference on rtentry, so can
144          * safely pass pointers to its contents.
145          */
146         RT_UNLOCK(rt);
147 
148         in_rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL,
149             rt->rt_fibnum);
150 }
151 
152 /*
153  * Parallel to llc_rtrequest.
154  */
155 static void
156 arp_rtrequest(int req, struct rtentry *rt, struct rt_addrinfo *info)
157 {
158         INIT_VNET_NET(curvnet);
159         INIT_VNET_INET(curvnet);
160         struct sockaddr *gate;
161         struct llinfo_arp *la;
162         static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
163         struct in_ifaddr *ia;
164         struct ifaddr *ifa;
165 
166         RT_LOCK_ASSERT(rt);
167 
168         if (rt->rt_flags & RTF_GATEWAY)
169                 return;
170         gate = rt->rt_gateway;
171         la = (struct llinfo_arp *)rt->rt_llinfo;
172         switch (req) {
173 
174         case RTM_ADD:
175                 /*
176                  * XXX: If this is a manually added route to interface
177                  * such as older version of routed or gated might provide,
178                  * restore cloning bit.
179                  */
180                 if ((rt->rt_flags & RTF_HOST) == 0 &&
181                     rt_mask(rt) != NULL &&
182                     SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
183                         rt->rt_flags |= RTF_CLONING;
184                 if (rt->rt_flags & RTF_CLONING) {
185                         /*
186                          * Case 1: This route should come from a route to iface.
187                          */
188                         rt_setgate(rt, rt_key(rt),
189                                         (struct sockaddr *)&null_sdl);
190                         gate = rt->rt_gateway;
191                         SDL(gate)->sdl_type = rt->rt_ifp->if_type;
192                         SDL(gate)->sdl_index = rt->rt_ifp->if_index;
193                         rt->rt_expire = time_uptime;
194                         break;
195                 }
196                 /* Announce a new entry if requested. */
197                 if (rt->rt_flags & RTF_ANNOUNCE)
198                         arprequest(rt->rt_ifp,
199                             &SIN(rt_key(rt))->sin_addr,
200                             &SIN(rt_key(rt))->sin_addr,
201                             (u_char *)LLADDR(SDL(gate)));
202                 /*FALLTHROUGH*/
203         case RTM_RESOLVE:
204                 if (gate->sa_family != AF_LINK ||
205                     gate->sa_len < sizeof(null_sdl)) {
206                         log(LOG_DEBUG, "%s: bad gateway %s%s\n", __func__,
207                             inet_ntoa(SIN(rt_key(rt))->sin_addr),
208                             (gate->sa_family != AF_LINK) ?
209                             " (!AF_LINK)": "");
210                         break;
211                 }
212                 SDL(gate)->sdl_type = rt->rt_ifp->if_type;
213                 SDL(gate)->sdl_index = rt->rt_ifp->if_index;
214                 if (la != 0)
215                         break; /* This happens on a route change */
216                 /*
217                  * Case 2:  This route may come from cloning, or a manual route
218                  * add with a LL address.
219                  */
220                 R_Zalloc(la, struct llinfo_arp *, sizeof(*la));
221                 rt->rt_llinfo = (caddr_t)la;
222                 if (la == 0) {
223                         log(LOG_DEBUG, "%s: malloc failed\n", __func__);
224                         break;
225                 }
226                 /*
227                  * We are storing a route entry outside of radix tree. So,
228                  * it can be found and accessed by other means than radix
229                  * lookup. The routing code assumes that any rtentry detached
230                  * from radix can be destroyed safely. To prevent this, we
231                  * add an additional reference.
232                  */
233                 RT_ADDREF(rt);
234                 la->la_rt = rt;
235                 rt->rt_flags |= RTF_LLINFO;
236                 callout_init_mtx(&la->la_timer, &rt->rt_mtx,
237                     CALLOUT_RETURNUNLOCKED);
238 
239 #ifdef INET
240                 /*
241                  * This keeps the multicast addresses from showing up
242                  * in `arp -a' listings as unresolved.  It's not actually
243                  * functional.  Then the same for broadcast.
244                  */
245                 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr)) &&
246                     rt->rt_ifp->if_type != IFT_ARCNET) {
247                         ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr,
248                                                LLADDR(SDL(gate)));
249                         SDL(gate)->sdl_alen = 6;
250                         rt->rt_expire = 0;
251                 }
252                 if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
253                         memcpy(LLADDR(SDL(gate)), rt->rt_ifp->if_broadcastaddr,
254                                rt->rt_ifp->if_addrlen);
255                         SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen;
256                         rt->rt_expire = 0;
257                 }
258 #endif
259 
260                 TAILQ_FOREACH(ia, &V_in_ifaddrhead, ia_link) {
261                         if (ia->ia_ifp == rt->rt_ifp &&
262                             SIN(rt_key(rt))->sin_addr.s_addr ==
263                             (IA_SIN(ia))->sin_addr.s_addr)
264                                 break;
265                 }
266                 if (ia) {
267                     /*
268                      * This test used to be
269                      *  if (loif.if_flags & IFF_UP)
270                      * It allowed local traffic to be forced
271                      * through the hardware by configuring the loopback down.
272                      * However, it causes problems during network configuration
273                      * for boards that can't receive packets they send.
274                      * It is now necessary to clear "useloopback" and remove
275                      * the route to force traffic out to the hardware.
276                      */
277                         rt->rt_expire = 0;
278                         bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)),
279                               SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen);
280                         if (V_useloopback) {
281                                 rt->rt_ifp = V_loif;
282                                 rt->rt_rmx.rmx_mtu = V_loif->if_mtu;
283                         }
284 
285                     /*
286                      * make sure to set rt->rt_ifa to the interface
287                      * address we are using, otherwise we will have trouble
288                      * with source address selection.
289                      */
290                         ifa = &ia->ia_ifa;
291                         if (ifa != rt->rt_ifa) {
292                                 IFAFREE(rt->rt_ifa);
293                                 IFAREF(ifa);
294                                 rt->rt_ifa = ifa;
295                         }
296                 }
297                 break;
298 
299         case RTM_DELETE:
300                 if (la == NULL) /* XXX: at least CARP does this. */
301                         break;
302                 callout_stop(&la->la_timer);
303                 rt->rt_llinfo = NULL;
304                 rt->rt_flags &= ~RTF_LLINFO;
305                 RT_REMREF(rt);
306                 if (la->la_hold)
307                         m_freem(la->la_hold);
308                 Free((caddr_t)la);
309         }
310 }
311 
312 /*
313  * Broadcast an ARP request. Caller specifies:
314  *      - arp header source ip address
315  *      - arp header target ip address
316  *      - arp header source ethernet address
317  */
318 static void
319 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,
320     u_char *enaddr)
321 {
322         struct mbuf *m;
323         struct arphdr *ah;
324         struct sockaddr sa;
325 
326         if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
327                 return;
328         m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
329                 2*ifp->if_data.ifi_addrlen;
330         m->m_pkthdr.len = m->m_len;
331         MH_ALIGN(m, m->m_len);
332         ah = mtod(m, struct arphdr *);
333         bzero((caddr_t)ah, m->m_len);
334 #ifdef MAC
335         mac_netinet_arp_send(ifp, m);
336 #endif
337         ah->ar_pro = htons(ETHERTYPE_IP);
338         ah->ar_hln = ifp->if_addrlen;           /* hardware address length */
339         ah->ar_pln = sizeof(struct in_addr);    /* protocol address length */
340         ah->ar_op = htons(ARPOP_REQUEST);
341         bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
342         bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
343         bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
344         sa.sa_family = AF_ARP;
345         sa.sa_len = 2;
346         m->m_flags |= M_BCAST;
347         (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
348 
349         return;
350 }
351 
352 /*
353  * Resolve an IP address into an ethernet address.
354  * On input:
355  *    ifp is the interface we use
356  *    rt0 is the route to the final destination (possibly useless)
357  *    m is the mbuf. May be NULL if we don't have a packet.
358  *    dst is the next hop,
359  *    desten is where we want the address.
360  *
361  * On success, desten is filled in and the function returns 0;
362  * If the packet must be held pending resolution, we return EWOULDBLOCK
363  * On other errors, we return the corresponding error code.
364  * Note that m_freem() handles NULL.
365  */
366 int
367 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
368     struct sockaddr *dst, u_char *desten)
369 {
370         INIT_VNET_INET(ifp->if_vnet);
371         struct llinfo_arp *la = NULL;
372         struct rtentry *rt = NULL;
373         struct sockaddr_dl *sdl;
374         int error;
375         int fibnum = -1;
376 
377         if (m) {
378                 if (m->m_flags & M_BCAST) {
379                         /* broadcast */
380                         (void)memcpy(desten,
381                             ifp->if_broadcastaddr, ifp->if_addrlen);
382                         return (0);
383                 }
384                 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
385                         /* multicast */
386                         ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
387                         return (0);
388                 }
389                 fibnum = M_GETFIB(m);
390         }
391 
392         if (rt0 != NULL) {
393                 /* Look for a cached arp (ll) entry. */
394                 if (m == NULL)
395                         fibnum = rt0->rt_fibnum;
396                 error = rt_check(&rt, &rt0, dst);
397                 if (error) {
398                         m_freem(m);
399                         return error;
400                 }
401                 la = (struct llinfo_arp *)rt->rt_llinfo;
402                 if (la == NULL)
403                         RT_UNLOCK(rt);
404         }
405 
406         /*
407          * If we had no mbuf and no route, then hope the caller
408          * has a fib in mind because we are running out of ideas.
409          * I think this should not happen in current code.
410          * (kmacy would know).
411          */
412         if (fibnum == -1)
413                 fibnum = curthread->td_proc->p_fibnum; /* last gasp */
414 
415         if (la == NULL) {
416                 /*
417                  * We enter this block if rt0 was NULL,
418                  * or if rt found by rt_check() didn't have llinfo.
419                  * we should get a cloned route, which since it should
420                  * come from the local interface should have a ll entry.
421                  * It may be incomplete but that's ok.
422                  */
423                 rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0, fibnum);
424                 if (rt == NULL) {
425                         log(LOG_DEBUG,
426                             "arpresolve: can't allocate route for %s\n",
427                             inet_ntoa(SIN(dst)->sin_addr));
428                         m_freem(m);
429                         return (EINVAL); /* XXX */
430                 }
431                 la = (struct llinfo_arp *)rt->rt_llinfo;
432                 if (la == NULL) {
433                         RT_UNLOCK(rt);
434                         log(LOG_DEBUG,
435                             "arpresolve: can't allocate llinfo for %s\n",
436                             inet_ntoa(SIN(dst)->sin_addr));
437                         m_freem(m);
438                         return (EINVAL); /* XXX */
439                 }
440         }
441         sdl = SDL(rt->rt_gateway);
442         /*
443          * Check the address family and length is valid, the address
444          * is resolved; otherwise, try to resolve.
445          */
446         if ((rt->rt_expire == 0 || rt->rt_expire > time_uptime) &&
447             sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) {
448 
449                 bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
450 
451                 /*
452                  * If entry has an expiry time and it is approaching,
453                  * send an ARP request.
454                  */
455                 if ((rt->rt_expire != 0) &&
456                     (time_uptime + la->la_preempt > rt->rt_expire)) {
457                         struct in_addr sin = 
458                             SIN(rt->rt_ifa->ifa_addr)->sin_addr;
459 
460                         la->la_preempt--;
461                         RT_UNLOCK(rt);
462                         arprequest(ifp, &sin, &SIN(dst)->sin_addr,
463                             IF_LLADDR(ifp));
464                         return (0);
465                 } 
466 
467                 RT_UNLOCK(rt);
468                 return (0);
469         }
470         /*
471          * If ARP is disabled or static on this interface, stop.
472          * XXX
473          * Probably should not allocate empty llinfo struct if we are
474          * not going to be sending out an arp request.
475          */
476         if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) {
477                 RT_UNLOCK(rt);
478                 m_freem(m);
479                 return (EINVAL);
480         }
481         /*
482          * There is an arptab entry, but no ethernet address
483          * response yet.  Replace the held mbuf with this
484          * latest one.
485          */
486         if (m) {
487                 if (la->la_hold)
488                         m_freem(la->la_hold);
489                 la->la_hold = m;
490         }
491         KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry"));
492 
493         /*
494          * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
495          * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
496          * if we have already sent arp_maxtries ARP requests. Retransmit the
497          * ARP request, but not faster than one request per second.
498          */
499         if (la->la_asked < V_arp_maxtries)
500                 error = EWOULDBLOCK;    /* First request. */
501         else
502                 error = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH;
503 
504         if (la->la_asked == 0 || rt->rt_expire != time_uptime) {
505                 struct in_addr sin =
506                     SIN(rt->rt_ifa->ifa_addr)->sin_addr;
507 
508                 rt->rt_expire = time_uptime;
509                 callout_reset(&la->la_timer, hz, arptimer, rt);
510                 la->la_asked++;
511                 RT_UNLOCK(rt);
512 
513                 arprequest(ifp, &sin, &SIN(dst)->sin_addr,
514                     IF_LLADDR(ifp));
515         } else
516                 RT_UNLOCK(rt);
517 
518         return (error);
519 }
520 
521 /*
522  * Common length and type checks are done here,
523  * then the protocol-specific routine is called.
524  */
525 static void
526 arpintr(struct mbuf *m)
527 {
528         struct arphdr *ar;
529 
530         if (m->m_len < sizeof(struct arphdr) &&
531             ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
532                 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
533                 return;
534         }
535         ar = mtod(m, struct arphdr *);
536 
537         if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
538             ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
539             ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
540             ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
541                 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
542                     (unsigned char *)&ar->ar_hrd, "");
543                 m_freem(m);
544                 return;
545         }
546 
547         if (m->m_len < arphdr_len(ar)) {
548                 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
549                         log(LOG_ERR, "arp: runt packet\n");
550                         m_freem(m);
551                         return;
552                 }
553                 ar = mtod(m, struct arphdr *);
554         }
555 
556         switch (ntohs(ar->ar_pro)) {
557 #ifdef INET
558         case ETHERTYPE_IP:
559                 in_arpinput(m);
560                 return;
561 #endif
562         }
563         m_freem(m);
564 }
565 
566 #ifdef INET
567 /*
568  * ARP for Internet protocols on 10 Mb/s Ethernet.
569  * Algorithm is that given in RFC 826.
570  * In addition, a sanity check is performed on the sender
571  * protocol address, to catch impersonators.
572  * We no longer handle negotiations for use of trailer protocol:
573  * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
574  * along with IP replies if we wanted trailers sent to us,
575  * and also sent them in response to IP replies.
576  * This allowed either end to announce the desire to receive
577  * trailer packets.
578  * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
579  * but formerly didn't normally send requests.
580  */
581 static int log_arp_wrong_iface = 1;
582 static int log_arp_movements = 1;
583 static int log_arp_permanent_modify = 1;
584 
585 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
586         &log_arp_wrong_iface, 0,
587         "log arp packets arriving on the wrong interface");
588 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
589         &log_arp_movements, 0,
590         "log arp replies from MACs different than the one in the cache");
591 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
592         &log_arp_permanent_modify, 0,
593         "log arp replies from MACs different than the one in the permanent arp entry");
594 
595 
596 static void
597 in_arpinput(struct mbuf *m)
598 {
599         struct arphdr *ah;
600         struct ifnet *ifp = m->m_pkthdr.rcvif;
601         struct llinfo_arp *la;
602         struct rtentry *rt;
603         struct ifaddr *ifa;
604         struct in_ifaddr *ia;
605         struct sockaddr_dl *sdl;
606         struct sockaddr sa;
607         struct in_addr isaddr, itaddr, myaddr;
608         struct mbuf *hold;
609         u_int8_t *enaddr = NULL;
610         int op, rif_len;
611         int req_len;
612         int bridged = 0, is_bridge = 0;
613         u_int fibnum;
614         u_int goodfib = 0;
615         int firstpass = 1;
616 #ifdef DEV_CARP
617         int carp_match = 0;
618 #endif
619         struct sockaddr_in sin;
620         sin.sin_len = sizeof(struct sockaddr_in);
621         sin.sin_family = AF_INET;
622         sin.sin_addr.s_addr = 0;
623         INIT_VNET_INET(ifp->if_vnet);
624 
625         if (ifp->if_bridge)
626                 bridged = 1;
627         if (ifp->if_type == IFT_BRIDGE)
628                 is_bridge = 1;
629 
630         req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
631         if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
632                 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
633                 return;
634         }
635 
636         ah = mtod(m, struct arphdr *);
637         op = ntohs(ah->ar_op);
638         (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
639         (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
640 
641         /*
642          * For a bridge, we want to check the address irrespective
643          * of the receive interface. (This will change slightly
644          * when we have clusters of interfaces).
645          * If the interface does not match, but the recieving interface
646          * is part of carp, we call carp_iamatch to see if this is a
647          * request for the virtual host ip.
648          * XXX: This is really ugly!
649          */
650         LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
651                 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
652                     (ia->ia_ifp == ifp)) &&
653                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
654                         goto match;
655 #ifdef DEV_CARP
656                 if (ifp->if_carp != NULL &&
657                     carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) &&
658                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
659                         carp_match = 1;
660                         goto match;
661                 }
662 #endif
663         }
664         LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
665                 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
666                     (ia->ia_ifp == ifp)) &&
667                     isaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
668                         goto match;
669 
670 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia)                           \
671   (ia->ia_ifp->if_bridge == ifp->if_softc &&                            \
672   !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) &&      \
673   addr == ia->ia_addr.sin_addr.s_addr)
674         /*
675          * Check the case when bridge shares its MAC address with
676          * some of its children, so packets are claimed by bridge
677          * itself (bridge_input() does it first), but they are really
678          * meant to be destined to the bridge member.
679          */
680         if (is_bridge) {
681                 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
682                         if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
683                                 ifp = ia->ia_ifp;
684                                 goto match;
685                         }
686                 }
687         }
688 #undef BDG_MEMBER_MATCHES_ARP
689 
690         /*
691          * No match, use the first inet address on the receive interface
692          * as a dummy address for the rest of the function.
693          */
694         TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
695                 if (ifa->ifa_addr->sa_family == AF_INET) {
696                         ia = ifatoia(ifa);
697                         goto match;
698                 }
699         /*
700          * If bridging, fall back to using any inet address.
701          */
702         if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL)
703                 goto drop;
704 match:
705         if (!enaddr)
706                 enaddr = (u_int8_t *)IF_LLADDR(ifp);
707         myaddr = ia->ia_addr.sin_addr;
708         if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
709                 goto drop;      /* it's from me, ignore it. */
710         if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
711                 log(LOG_ERR,
712                     "arp: link address is broadcast for IP address %s!\n",
713                     inet_ntoa(isaddr));
714                 goto drop;
715         }
716         /*
717          * Warn if another host is using the same IP address, but only if the
718          * IP address isn't 0.0.0.0, which is used for DHCP only, in which
719          * case we suppress the warning to avoid false positive complaints of
720          * potential misconfiguration.
721          */
722         if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
723                 log(LOG_ERR,
724                    "arp: %*D is using my IP address %s on %s!\n",
725                    ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
726                    inet_ntoa(isaddr), ifp->if_xname);
727                 itaddr = myaddr;
728                 goto reply;
729         }
730         if (ifp->if_flags & IFF_STATICARP)
731                 goto reply;
732         /*
733          * We look for any FIB that has this address to find
734          * the interface etc.
735          * For sanity checks that are FIB independent we abort the loop.
736          */
737         for (fibnum = 0; fibnum < rt_numfibs; fibnum++) {
738                 rt = arplookup(isaddr.s_addr,
739                     itaddr.s_addr == myaddr.s_addr, 0, fibnum);
740                 if (rt == NULL)
741                         continue;
742                 
743                 sdl = SDL(rt->rt_gateway);
744                 /* Only call this once */
745                 if (firstpass) {
746                         sin.sin_addr.s_addr = isaddr.s_addr;
747                         EVENTHANDLER_INVOKE(route_arp_update_event, rt,
748                             ar_sha(ah), (struct sockaddr *)&sin);
749                 }
750                 
751                 la = (struct llinfo_arp *)rt->rt_llinfo;
752                 if (la == NULL) {
753                         RT_UNLOCK(rt);
754                         continue;
755                 }
756 
757                 if (firstpass) {
758                         /* The following is not an error when doing bridging. */
759                         if (!bridged && rt->rt_ifp != ifp
760 #ifdef DEV_CARP
761                             && (ifp->if_type != IFT_CARP || !carp_match)
762 #endif
763                             ) {
764                                 if (log_arp_wrong_iface)
765                                         log(LOG_ERR, "arp: %s is on %s "
766                                                 "but got reply from %*D "
767                                                 "on %s\n",
768                                             inet_ntoa(isaddr),
769                                             rt->rt_ifp->if_xname,
770                                             ifp->if_addrlen,
771                                             (u_char *)ar_sha(ah), ":",
772                                             ifp->if_xname);
773                                 RT_UNLOCK(rt);
774                                 break;
775                         }
776                         if (sdl->sdl_alen &&
777                             bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) {
778                                 if (rt->rt_expire) {
779                                     if (log_arp_movements)
780                                         log(LOG_INFO,
781                                             "arp: %s moved from %*D to %*D "
782                                             "on %s\n",
783                                             inet_ntoa(isaddr),
784                                             ifp->if_addrlen,
785                                             (u_char *)LLADDR(sdl), ":",
786                                             ifp->if_addrlen,
787                                             (u_char *)ar_sha(ah), ":",
788                                             ifp->if_xname);
789                                 } else {
790                                         RT_UNLOCK(rt);
791                                         if (log_arp_permanent_modify)
792                                                 log(LOG_ERR,
793                                                     "arp: %*D attempts to "
794                                                     "modify permanent entry "
795                                                     "for %s on %s\n",
796                                                     ifp->if_addrlen,
797                                                     (u_char *)ar_sha(ah), ":",
798                                                     inet_ntoa(isaddr),
799                                                     ifp->if_xname);
800                                         break;
801                                 }
802                         }
803                         /*
804                          * sanity check for the address length.
805                          * XXX this does not work for protocols
806                          * with variable address length. -is
807                          */
808                         if (sdl->sdl_alen &&
809                             sdl->sdl_alen != ah->ar_hln) {
810                                 log(LOG_WARNING,
811                                     "arp from %*D: new addr len %d, was %d",
812                                     ifp->if_addrlen, (u_char *) ar_sha(ah),
813                                     ":", ah->ar_hln, sdl->sdl_alen);
814                         }
815                         if (ifp->if_addrlen != ah->ar_hln) {
816                                 log(LOG_WARNING,
817                                     "arp from %*D: addr len: "
818                                     "new %d, i/f %d (ignored)",
819                                     ifp->if_addrlen, (u_char *) ar_sha(ah),
820                                     ":", ah->ar_hln, ifp->if_addrlen);
821                                 RT_UNLOCK(rt);
822                                 break;
823                         }
824                         firstpass = 0;
825                         goodfib = fibnum;
826                 }
827 
828                 /* Copy in the information received. */
829                 (void)memcpy(LLADDR(sdl), ar_sha(ah),
830                     sdl->sdl_alen = ah->ar_hln);
831                 /*
832                  * If we receive an arp from a token-ring station over
833                  * a token-ring nic then try to save the source routing info.
834                  * XXXMRT Only minimal Token Ring support for MRT.
835                  * Only do this on the first pass as if modifies the mbuf.
836                  */
837                 if (ifp->if_type == IFT_ISO88025) {
838                         struct iso88025_header *th = NULL;
839                         struct iso88025_sockaddr_dl_data *trld;
840 
841                         /* force the fib loop to end after this pass */
842                         fibnum = rt_numfibs - 1;
843 
844                         th = (struct iso88025_header *)m->m_pkthdr.header;
845                         trld = SDL_ISO88025(sdl);
846                         rif_len = TR_RCF_RIFLEN(th->rcf);
847                         if ((th->iso88025_shost[0] & TR_RII) &&
848                             (rif_len > 2)) {
849                                 trld->trld_rcf = th->rcf;
850                                 trld->trld_rcf ^= htons(TR_RCF_DIR);
851                                 memcpy(trld->trld_route, th->rd, rif_len - 2);
852                                 trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK);
853                                 /*
854                                  * Set up source routing information for
855                                  * reply packet (XXX)
856                                  */
857                                 m->m_data -= rif_len;
858                                 m->m_len  += rif_len;
859                                 m->m_pkthdr.len += rif_len;
860                         } else {
861                                 th->iso88025_shost[0] &= ~TR_RII;
862                                 trld->trld_rcf = 0;
863                         }
864                         m->m_data -= 8;
865                         m->m_len  += 8;
866                         m->m_pkthdr.len += 8;
867                         th->rcf = trld->trld_rcf;
868                 }
869 
870                 if (rt->rt_expire) {
871                         rt->rt_expire = time_uptime + V_arpt_keep;
872                         callout_reset(&la->la_timer, hz * V_arpt_keep,
873                             arptimer, rt);
874                 }
875                 la->la_asked = 0;
876                 la->la_preempt = V_arp_maxtries;
877                 hold = la->la_hold;
878                 la->la_hold = NULL;
879                 RT_UNLOCK(rt);
880                 if (hold != NULL)
881                         (*ifp->if_output)(ifp, hold, rt_key(rt), rt);
882         } /* end of FIB loop */
883 reply:
884 
885         /*
886          * Decide if we have to respond to something.
887          */
888         if (op != ARPOP_REQUEST)
889                 goto drop;
890         if (itaddr.s_addr == myaddr.s_addr) {
891                 /* Shortcut.. the receiving interface is the target. */
892                 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
893                 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
894         } else {
895                 /* It's not asking for our address. But it still may
896                  * be something we should answer.
897                  *
898                  * XXX MRT
899                  * We assume that link level info is independent of
900                  * the table used and so we use whichever we can and don't
901                  * have a better option.
902                  */
903                 /* Have we been asked to proxy for the target. */
904                 rt = arplookup(itaddr.s_addr, 0, SIN_PROXY, goodfib);
905                 if (rt == NULL) {
906                         /* Nope, only intersted now if proxying everything. */
907                         struct sockaddr_in sin;
908 
909                         if (!V_arp_proxyall)
910                                 goto drop;
911 
912                         bzero(&sin, sizeof sin);
913                         sin.sin_family = AF_INET;
914                         sin.sin_len = sizeof sin;
915                         sin.sin_addr = itaddr;
916 
917                         /* XXX MRT use table 0 for arp reply  */
918                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
919                         if (!rt)
920                                 goto drop;
921                         /*
922                          * Don't send proxies for nodes on the same interface
923                          * as this one came out of, or we'll get into a fight
924                          * over who claims what Ether address.
925                          */
926                         if (rt->rt_ifp == ifp) {
927                                 rtfree(rt);
928                                 goto drop;
929                         }
930                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
931                         (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
932                         rtfree(rt);
933 
934                         /*
935                          * Also check that the node which sent the ARP packet
936                          * is on the the interface we expect it to be on. This
937                          * avoids ARP chaos if an interface is connected to the