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("$FreeBSD$");
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 llentry *lle = (struct llentry *)arg;
171 struct ifnet *ifp;
172 size_t pkts_dropped;
173
174 if (lle->la_flags & LLE_STATIC) {
175 LLE_WUNLOCK(lle);
176 return;
177 }
178
179 ifp = lle->lle_tbl->llt_ifp;
180 CURVNET_SET(ifp->if_vnet);
181
182 callout_stop(&lle->la_timer);
183
184 /* XXX: LOR avoidance. We still have ref on lle. */
185 LLE_WUNLOCK(lle);
186 IF_AFDATA_LOCK(ifp);
187 LLE_WLOCK(lle);
188
189 LLE_REMREF(lle);
190 pkts_dropped = llentry_free(lle);
191 IF_AFDATA_UNLOCK(ifp);
192 ARPSTAT_ADD(dropped, pkts_dropped);
193 ARPSTAT_INC(timeouts);
194 CURVNET_RESTORE();
195 }
196
197 /*
198 * Broadcast an ARP request. Caller specifies:
199 * - arp header source ip address
200 * - arp header target ip address
201 * - arp header source ethernet address
202 */
203 void
204 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,
205 u_char *enaddr)
206 {
207 struct mbuf *m;
208 struct arphdr *ah;
209 struct sockaddr sa;
210
211 if (sip == NULL) {
212 /* XXX don't believe this can happen (or explain why) */
213 /*
214 * The caller did not supply a source address, try to find
215 * a compatible one among those assigned to this interface.
216 */
217 struct ifaddr *ifa;
218
219 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
220 if (!ifa->ifa_addr ||
221 ifa->ifa_addr->sa_family != AF_INET)
222 continue;
223 sip = &SIN(ifa->ifa_addr)->sin_addr;
224 if (0 == ((sip->s_addr ^ tip->s_addr) &
225 SIN(ifa->ifa_netmask)->sin_addr.s_addr) )
226 break; /* found it. */
227 }
228 if (sip == NULL) {
229 printf("%s: cannot find matching address\n", __func__);
230 return;
231 }
232 }
233
234 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
235 return;
236 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
237 2*ifp->if_data.ifi_addrlen;
238 m->m_pkthdr.len = m->m_len;
239 MH_ALIGN(m, m->m_len);
240 ah = mtod(m, struct arphdr *);
241 bzero((caddr_t)ah, m->m_len);
242 #ifdef MAC
243 mac_netinet_arp_send(ifp, m);
244 #endif
245 ah->ar_pro = htons(ETHERTYPE_IP);
246 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
247 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
248 ah->ar_op = htons(ARPOP_REQUEST);
249 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
250 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
251 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
252 sa.sa_family = AF_ARP;
253 sa.sa_len = 2;
254 m->m_flags |= M_BCAST;
255 (*ifp->if_output)(ifp, m, &sa, NULL);
256 ARPSTAT_INC(txrequests);
257 }
258
259 /*
260 * Resolve an IP address into an ethernet address.
261 * On input:
262 * ifp is the interface we use
263 * rt0 is the route to the final destination (possibly useless)
264 * m is the mbuf. May be NULL if we don't have a packet.
265 * dst is the next hop,
266 * desten is where we want the address.
267 *
268 * On success, desten is filled in and the function returns 0;
269 * If the packet must be held pending resolution, we return EWOULDBLOCK
270 * On other errors, we return the corresponding error code.
271 * Note that m_freem() handles NULL.
272 */
273 int
274 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
275 struct sockaddr *dst, u_char *desten, struct llentry **lle)
276 {
277 struct llentry *la = 0;
278 u_int flags = 0;
279 struct mbuf *curr = NULL;
280 struct mbuf *next = NULL;
281 int error, renew;
282
283 *lle = NULL;
284 if (m != NULL) {
285 if (m->m_flags & M_BCAST) {
286 /* broadcast */
287 (void)memcpy(desten,
288 ifp->if_broadcastaddr, ifp->if_addrlen);
289 return (0);
290 }
291 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
292 /* multicast */
293 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
294 return (0);
295 }
296 }
297 /* XXXXX
298 */
299 retry:
300 IF_AFDATA_RLOCK(ifp);
301 la = lla_lookup(LLTABLE(ifp), flags, dst);
302 IF_AFDATA_RUNLOCK(ifp);
303 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
304 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
305 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
306 IF_AFDATA_WLOCK(ifp);
307 la = lla_lookup(LLTABLE(ifp), flags, dst);
308 IF_AFDATA_WUNLOCK(ifp);
309 }
310 if (la == NULL) {
311 if (flags & LLE_CREATE)
312 log(LOG_DEBUG,
313 "arpresolve: can't allocate llinfo for %s\n",
314 inet_ntoa(SIN(dst)->sin_addr));
315 m_freem(m);
316 return (EINVAL);
317 }
318
319 if ((la->la_flags & LLE_VALID) &&
320 ((la->la_flags & LLE_STATIC) || la->la_expire > time_second)) {
321 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
322 /*
323 * If entry has an expiry time and it is approaching,
324 * see if we need to send an ARP request within this
325 * arpt_down interval.
326 */
327 if (!(la->la_flags & LLE_STATIC) &&
328 time_second + la->la_preempt > la->la_expire) {
329 arprequest(ifp, NULL,
330 &SIN(dst)->sin_addr, IF_LLADDR(ifp));
331
332 la->la_preempt--;
333 }
334
335 *lle = la;
336 error = 0;
337 goto done;
338 }
339
340 if (la->la_flags & LLE_STATIC) { /* should not happen! */
341 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
342 inet_ntoa(SIN(dst)->sin_addr));
343 m_freem(m);
344 error = EINVAL;
345 goto done;
346 }
347
348 renew = (la->la_asked == 0 || la->la_expire != time_second);
349 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
350 flags |= LLE_EXCLUSIVE;
351 LLE_RUNLOCK(la);
352 goto retry;
353 }
354 /*
355 * There is an arptab entry, but no ethernet address
356 * response yet. Add the mbuf to the list, dropping
357 * the oldest packet if we have exceeded the system
358 * setting.
359 */
360 if (m != NULL) {
361 if (la->la_numheld >= V_arp_maxhold) {
362 if (la->la_hold != NULL) {
363 next = la->la_hold->m_nextpkt;
364 m_freem(la->la_hold);
365 la->la_hold = next;
366 la->la_numheld--;
367 ARPSTAT_INC(dropped);
368 }
369 }
370 if (la->la_hold != NULL) {
371 curr = la->la_hold;
372 while (curr->m_nextpkt != NULL)
373 curr = curr->m_nextpkt;
374 curr->m_nextpkt = m;
375 } else
376 la->la_hold = m;
377 la->la_numheld++;
378 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
379 flags &= ~LLE_EXCLUSIVE;
380 LLE_DOWNGRADE(la);
381 }
382
383 }
384 /*
385 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
386 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
387 * if we have already sent arp_maxtries ARP requests. Retransmit the
388 * ARP request, but not faster than one request per second.
389 */
390 if (la->la_asked < V_arp_maxtries)
391 error = EWOULDBLOCK; /* First request. */
392 else
393 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ?
394 EHOSTUNREACH : EHOSTDOWN;
395
396 if (renew) {
397 int canceled;
398
399 LLE_ADDREF(la);
400 la->la_expire = time_second;
401 canceled = callout_reset(&la->la_timer, hz * V_arpt_down,
402 arptimer, la);
403 if (canceled)
404 LLE_REMREF(la);
405 la->la_asked++;
406 LLE_WUNLOCK(la);
407 arprequest(ifp, NULL, &SIN(dst)->sin_addr,
408 IF_LLADDR(ifp));
409 return (error);
410 }
411 done:
412 if (flags & LLE_EXCLUSIVE)
413 LLE_WUNLOCK(la);
414 else
415 LLE_RUNLOCK(la);
416 return (error);
417 }
418
419 /*
420 * Common length and type checks are done here,
421 * then the protocol-specific routine is called.
422 */
423 static void
424 arpintr(struct mbuf *m)
425 {
426 struct arphdr *ar;
427
428 if (m->m_len < sizeof(struct arphdr) &&
429 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
430 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
431 return;
432 }
433 ar = mtod(m, struct arphdr *);
434
435 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
436 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
437 ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
438 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
439 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
440 (unsigned char *)&ar->ar_hrd, "");
441 m_freem(m);
442 return;
443 }
444
445 if (m->m_len < arphdr_len(ar)) {
446 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
447 log(LOG_ERR, "arp: runt packet\n");
448 m_freem(m);
449 return;
450 }
451 ar = mtod(m, struct arphdr *);
452 }
453
454 ARPSTAT_INC(received);
455 switch (ntohs(ar->ar_pro)) {
456 #ifdef INET
457 case ETHERTYPE_IP:
458 in_arpinput(m);
459 return;
460 #endif
461 }
462 m_freem(m);
463 }
464
465 #ifdef INET
466 /*
467 * ARP for Internet protocols on 10 Mb/s Ethernet.
468 * Algorithm is that given in RFC 826.
469 * In addition, a sanity check is performed on the sender
470 * protocol address, to catch impersonators.
471 * We no longer handle negotiations for use of trailer protocol:
472 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
473 * along with IP replies if we wanted trailers sent to us,
474 * and also sent them in response to IP replies.
475 * This allowed either end to announce the desire to receive
476 * trailer packets.
477 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
478 * but formerly didn't normally send requests.
479 */
480 static int log_arp_wrong_iface = 1;
481 static int log_arp_movements = 1;
482 static int log_arp_permanent_modify = 1;
483
484 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
485 &log_arp_wrong_iface, 0,
486 "log arp packets arriving on the wrong interface");
487 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
488 &log_arp_movements, 0,
489 "log arp replies from MACs different than the one in the cache");
490 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
491 &log_arp_permanent_modify, 0,
492 "log arp replies from MACs different than the one in the permanent arp entry");
493
494
495 static void
496 in_arpinput(struct mbuf *m)
497 {
498 struct arphdr *ah;
499 struct ifnet *ifp = m->m_pkthdr.rcvif;
500 struct llentry *la = NULL;
501 struct rtentry *rt;
502 struct ifaddr *ifa;
503 struct in_ifaddr *ia;
504 struct sockaddr sa;
505 struct in_addr isaddr, itaddr, myaddr;
506 u_int8_t *enaddr = NULL;
507 int op, flags;
508 int req_len;
509 int bridged = 0, is_bridge = 0;
510 int carp_match = 0;
511 struct sockaddr_in sin;
512 sin.sin_len = sizeof(struct sockaddr_in);
513 sin.sin_family = AF_INET;
514 sin.sin_addr.s_addr = 0;
515
516 if (ifp->if_bridge)
517 bridged = 1;
518 if (ifp->if_type == IFT_BRIDGE)
519 is_bridge = 1;
520
521 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
522 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
523 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
524 return;
525 }
526
527 ah = mtod(m, struct arphdr *);
528 op = ntohs(ah->ar_op);
529 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
530 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
531
532 if (op == ARPOP_REPLY)
533 ARPSTAT_INC(rxreplies);
534
535 /*
536 * For a bridge, we want to check the address irrespective
537 * of the receive interface. (This will change slightly
538 * when we have clusters of interfaces).
539 * If the interface does not match, but the recieving interface
540 * is part of carp, we call carp_iamatch to see if this is a
541 * request for the virtual host ip.
542 * XXX: This is really ugly!
543 */
544 IN_IFADDR_RLOCK();
545 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
546 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
547 ia->ia_ifp == ifp) &&
548 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
549 ifa_ref(&ia->ia_ifa);
550 IN_IFADDR_RUNLOCK();
551 goto match;
552 }
553 if (ifp->if_carp != NULL &&
554 (*carp_iamatch_p)(ifp, ia, &isaddr, &enaddr) &&
555 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
556 carp_match = 1;
557 ifa_ref(&ia->ia_ifa);
558 IN_IFADDR_RUNLOCK();
559 goto match;
560 }
561 }
562 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
563 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
564 ia->ia_ifp == ifp) &&
565 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
566 ifa_ref(&ia->ia_ifa);
567 IN_IFADDR_RUNLOCK();
568 goto match;
569 }
570
571 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
572 (ia->ia_ifp->if_bridge == ifp->if_softc && \
573 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
574 addr == ia->ia_addr.sin_addr.s_addr)
575 /*
576 * Check the case when bridge shares its MAC address with
577 * some of its children, so packets are claimed by bridge
578 * itself (bridge_input() does it first), but they are really
579 * meant to be destined to the bridge member.
580 */
581 if (is_bridge) {
582 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
583 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
584 ifa_ref(&ia->ia_ifa);
585 ifp = ia->ia_ifp;
586 IN_IFADDR_RUNLOCK();
587 goto match;
588 }
589 }
590 }
591 #undef BDG_MEMBER_MATCHES_ARP
592 IN_IFADDR_RUNLOCK();
593
594 /*
595 * No match, use the first inet address on the receive interface
596 * as a dummy address for the rest of the function.
597 */
598 IF_ADDR_RLOCK(ifp);
599 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
600 if (ifa->ifa_addr->sa_family == AF_INET) {
601 ia = ifatoia(ifa);
602 ifa_ref(ifa);
603 IF_ADDR_RUNLOCK(ifp);
604 goto match;
605 }
606 IF_ADDR_RUNLOCK(ifp);
607
608 /*
609 * If bridging, fall back to using any inet address.
610 */
611 IN_IFADDR_RLOCK();
612 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
613 IN_IFADDR_RUNLOCK();
614 goto drop;
615 }
616 ifa_ref(&ia->ia_ifa);
617 IN_IFADDR_RUNLOCK();
618 match:
619 if (!enaddr)
620 enaddr = (u_int8_t *)IF_LLADDR(ifp);
621 myaddr = ia->ia_addr.sin_addr;
622 ifa_free(&ia->ia_ifa);
623 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
624 goto drop; /* it's from me, ignore it. */
625 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
626 log(LOG_ERR,
627 "arp: link address is broadcast for IP address %s!\n",
628 inet_ntoa(isaddr));
629 goto drop;
630 }
631 /*
632 * Warn if another host is using the same IP address, but only if the
633 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
634 * case we suppress the warning to avoid false positive complaints of
635 * potential misconfiguration.
636 */
637 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
638 log(LOG_ERR,
639 "arp: %*D is using my IP address %s on %s!\n",
640 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
641 inet_ntoa(isaddr), ifp->if_xname);
642 itaddr = myaddr;
643 ARPSTAT_INC(dupips);
644 goto reply;
645 }
646 if (ifp->if_flags & IFF_STATICARP)
647 goto reply;
648
649 bzero(&sin, sizeof(sin));
650 sin.sin_len = sizeof(struct sockaddr_in);
651 sin.sin_family = AF_INET;
652 sin.sin_addr = isaddr;
653 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
654 flags |= LLE_EXCLUSIVE;
655 IF_AFDATA_LOCK(ifp);
656 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
657 IF_AFDATA_UNLOCK(ifp);
658 if (la != NULL) {
659 /* the following is not an error when doing bridging */
660 if (!bridged && la->lle_tbl->llt_ifp != ifp && !carp_match) {
661 if (log_arp_wrong_iface)
662 log(LOG_ERR, "arp: %s is on %s "
663 "but got reply from %*D on %s\n",
664 inet_ntoa(isaddr),
665 la->lle_tbl->llt_ifp->if_xname,
666 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
667 ifp->if_xname);
668 LLE_WUNLOCK(la);
669 goto reply;
670 }
671 if ((la->la_flags & LLE_VALID) &&
672 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
673 if (la->la_flags & LLE_STATIC) {
674 LLE_WUNLOCK(la);
675 if (log_arp_permanent_modify)
676 log(LOG_ERR,
677 "arp: %*D attempts to modify "
678 "permanent entry for %s on %s\n",
679 ifp->if_addrlen,
680 (u_char *)ar_sha(ah), ":",
681 inet_ntoa(isaddr), ifp->if_xname);
682 goto reply;
683 }
684 if (log_arp_movements) {
685 log(LOG_INFO, "arp: %s moved from %*D "
686 "to %*D on %s\n",
687 inet_ntoa(isaddr),
688 ifp->if_addrlen,
689 (u_char *)&la->ll_addr, ":",
690 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
691 ifp->if_xname);
692 }
693 }
694
695 if (ifp->if_addrlen != ah->ar_hln) {
696 LLE_WUNLOCK(la);
697 log(LOG_WARNING,
698 "arp from %*D: addr len: new %d, i/f %d (ignored)",
699 ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
700 ah->ar_hln, ifp->if_addrlen);
701 goto reply;
702 }
703 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
704 la->la_flags |= LLE_VALID;
705
706 if (!(la->la_flags & LLE_STATIC)) {
707 int canceled;
708
709 LLE_ADDREF(la);
710 la->la_expire = time_second + V_arpt_keep;
711 canceled = callout_reset(&la->la_timer,
712 hz * V_arpt_keep, arptimer, la);
713 if (canceled)
714 LLE_REMREF(la);
715 }
716 la->la_asked = 0;
717 la->la_preempt = V_arp_maxtries;
718 /*
719 * The packets are all freed within the call to the output
720 * routine.
721 *
722 * NB: The lock MUST be released before the call to the
723 * output routine.
724 */
725 if (la->la_hold != NULL) {
726 struct mbuf *m_hold, *m_hold_next;
727
728 m_hold = la->la_hold;
729 la->la_hold = NULL;
730 la->la_numheld = 0;
731 memcpy(&sa, L3_ADDR(la), sizeof(sa));
732 LLE_WUNLOCK(la);
733 for (; m_hold != NULL; m_hold = m_hold_next) {
734 m_hold_next = m_hold->m_nextpkt;
735 m_hold->m_nextpkt = NULL;
736 (*ifp->if_output)(ifp, m_hold, &sa, NULL);
737 }
738 } else
739 LLE_WUNLOCK(la);
740 } /* end of FIB loop */
741 reply:
742 if (op != ARPOP_REQUEST)
743 goto drop;
744 ARPSTAT_INC(rxrequests);
745
746 if (itaddr.s_addr == myaddr.s_addr) {
747 /* Shortcut.. the receiving interface is the target. */
748 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
749 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
750 } else {
751 struct llentry *lle = NULL;
752
753 sin.sin_addr = itaddr;
754 IF_AFDATA_LOCK(ifp);
755 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
756 IF_AFDATA_UNLOCK(ifp);
757
758 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
759 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
760 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
761 LLE_RUNLOCK(lle);
762 } else {
763
764 if (lle != NULL)
765 LLE_RUNLOCK(lle);
766
767 if (!V_arp_proxyall)
768 goto drop;
769
770 sin.sin_addr = itaddr;
771 /* XXX MRT use table 0 for arp reply */
772 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
773 if (!rt)
774 goto drop;
775
776 /*
777 * Don't send proxies for nodes on the same interface
778 * as this one came out of, or we'll get into a fight
779 * over who claims what Ether address.
780 */
781 if (!rt->rt_ifp || rt->rt_ifp == ifp) {
782 RTFREE_LOCKED(rt);
783 goto drop;
784 }
785 RTFREE_LOCKED(rt);
786
787 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
788 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
789
790 /*
791 * Also check that the node which sent the ARP packet
792 * is on the interface we expect it to be on. This
793 * avoids ARP chaos if an interface is connected to the
794 * wrong network.
795 */
796 sin.sin_addr = isaddr;
797
798 /* XXX MRT use table 0 for arp checks */
799 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
800 if (!rt)
801 goto drop;
802 if (rt->rt_ifp != ifp) {
803 log(LOG_INFO, "arp_proxy: ignoring request"
804 " from %s via %s, expecting %s\n",
805 inet_ntoa(isaddr), ifp->if_xname,
806 rt->rt_ifp->if_xname);
807 RTFREE_LOCKED(rt);
808 goto drop;
809 }
810 RTFREE_LOCKED(rt);
811
812 #ifdef DEBUG_PROXY
813 printf("arp: proxying for %s\n",
814 inet_ntoa(itaddr));
815 #endif
816 }
817 }
818
819 if (itaddr.s_addr == myaddr.s_addr &&
820 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
821 /* RFC 3927 link-local IPv4; always reply by broadcast. */
822 #ifdef DEBUG_LINKLOCAL
823 printf("arp: sending reply for link-local addr %s\n",
824 inet_ntoa(itaddr));
825 #endif
826 m->m_flags |= M_BCAST;
827 m->m_flags &= ~M_MCAST;
828 } else {
829 /* default behaviour; never reply by broadcast. */
830 m->m_flags &= ~(M_BCAST|M_MCAST);
831 }
832 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
833 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
834 ah->ar_op = htons(ARPOP_REPLY);
835 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
836 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
837 m->m_pkthdr.len = m->m_len;
838 m->m_pkthdr.rcvif = NULL;
839 sa.sa_family = AF_ARP;
840 sa.sa_len = 2;
841 (*ifp->if_output)(ifp, m, &sa, NULL);
842 ARPSTAT_INC(txreplies);
843 return;
844
845 drop:
846 m_freem(m);
847 }
848 #endif
849
850 void
851 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
852 {
853 struct llentry *lle;
854
855 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
856 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
857 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
858 /*
859 * interface address is considered static entry
860 * because the output of the arp utility shows
861 * that L2 entry as permanent
862 */
863 IF_AFDATA_LOCK(ifp);
864 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
865 (struct sockaddr *)IA_SIN(ifa));
866 IF_AFDATA_UNLOCK(ifp);
867 if (lle == NULL)
868 log(LOG_INFO, "arp_ifinit: cannot create arp "
869 "entry for interface address\n");
870 else
871 LLE_RUNLOCK(lle);
872 }
873 ifa->ifa_rtrequest = NULL;
874 }
875
876 void
877 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
878 {
879 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
880 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
881 &IA_SIN(ifa)->sin_addr, enaddr);
882 ifa->ifa_rtrequest = NULL;
883 }
884
885 static void
886 arp_init(void)
887 {
888
889 netisr_register(&arp_nh);
890 }
891 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);
Cache object: 700b32a748045c83485ca507af768b43
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