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: head/sys/netinet/if_ether.c 198418 2009-10-23 18:27:34Z qingli $");
40
41 #include "opt_inet.h"
42 #include "opt_carp.h"
43
44 #include <sys/param.h>
45 #include <sys/kernel.h>
46 #include <sys/queue.h>
47 #include <sys/sysctl.h>
48 #include <sys/systm.h>
49 #include <sys/mbuf.h>
50 #include <sys/malloc.h>
51 #include <sys/proc.h>
52 #include <sys/socket.h>
53 #include <sys/syslog.h>
54
55 #include <net/if.h>
56 #include <net/if_dl.h>
57 #include <net/if_types.h>
58 #include <net/netisr.h>
59 #include <net/if_llc.h>
60 #include <net/ethernet.h>
61 #include <net/route.h>
62 #include <net/vnet.h>
63
64 #include <netinet/in.h>
65 #include <netinet/in_var.h>
66 #include <net/if_llatbl.h>
67 #include <netinet/if_ether.h>
68
69 #include <net/if_arc.h>
70 #include <net/iso88025.h>
71
72 #ifdef DEV_CARP
73 #include <netinet/ip_carp.h>
74 #endif
75
76 #include <security/mac/mac_framework.h>
77
78 #define SIN(s) ((struct sockaddr_in *)s)
79 #define SDL(s) ((struct sockaddr_dl *)s)
80
81 SYSCTL_DECL(_net_link_ether);
82 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
83 SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, "");
84
85 VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for
86 * local traffic */
87
88 /* timer values */
89 static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20
90 * minutes */
91 static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for
92 * 20 seconds */
93 static VNET_DEFINE(int, arp_maxtries) = 5;
94 static VNET_DEFINE(int, arp_proxyall);
95 static VNET_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */
96
97 #define V_arpt_keep VNET(arpt_keep)
98 #define V_arpt_down VNET(arpt_down)
99 #define V_arp_maxtries VNET(arp_maxtries)
100 #define V_arp_proxyall VNET(arp_proxyall)
101 #define V_arpstat VNET(arpstat)
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
107 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
108 &VNET_NAME(arp_maxtries), 0,
109 "ARP resolution attempts before returning error");
110 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
111 &VNET_NAME(useloopback), 0,
112 "Use the loopback interface for local traffic");
113 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
114 &VNET_NAME(arp_proxyall), 0,
115 "Enable proxy ARP for all suitable requests");
116 SYSCTL_VNET_STRUCT(_net_link_ether_arp, OID_AUTO, stats, CTLFLAG_RW,
117 &VNET_NAME(arpstat), arpstat,
118 "ARP statistics (struct arpstat, net/if_arp.h)");
119
120 static void arp_init(void);
121 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 #ifdef INET
126 static void in_arpinput(struct mbuf *);
127 #endif
128
129 static const struct netisr_handler arp_nh = {
130 .nh_name = "arp",
131 .nh_handler = arpintr,
132 .nh_proto = NETISR_ARP,
133 .nh_policy = NETISR_POLICY_SOURCE,
134 };
135
136 #ifdef AF_INET
137 void arp_ifscrub(struct ifnet *ifp, uint32_t addr);
138
139 /*
140 * called by in_ifscrub to remove entry from the table when
141 * the interface goes away
142 */
143 void
144 arp_ifscrub(struct ifnet *ifp, uint32_t addr)
145 {
146 struct sockaddr_in addr4;
147
148 bzero((void *)&addr4, sizeof(addr4));
149 addr4.sin_len = sizeof(addr4);
150 addr4.sin_family = AF_INET;
151 addr4.sin_addr.s_addr = addr;
152 CURVNET_SET(ifp->if_vnet);
153 IF_AFDATA_LOCK(ifp);
154 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
155 (struct sockaddr *)&addr4);
156 IF_AFDATA_UNLOCK(ifp);
157 CURVNET_RESTORE();
158 }
159 #endif
160
161 /*
162 * Timeout routine. Age arp_tab entries periodically.
163 */
164 static void
165 arptimer(void *arg)
166 {
167 struct ifnet *ifp;
168 struct llentry *lle = (struct llentry *)arg;
169
170 if (lle == NULL) {
171 panic("%s: NULL entry!\n", __func__);
172 return;
173 }
174 ifp = lle->lle_tbl->llt_ifp;
175 CURVNET_SET(ifp->if_vnet);
176 IF_AFDATA_LOCK(ifp);
177 LLE_WLOCK(lle);
178 if ((!callout_pending(&lle->la_timer) &&
179 callout_active(&lle->la_timer))) {
180 (void) llentry_free(lle);
181 ARPSTAT_INC(timeouts);
182 }
183 #ifdef DIAGNOSTIC
184 else {
185 struct sockaddr *l3addr = L3_ADDR(lle);
186 log(LOG_INFO, "arptimer issue: %p, IPv4 address: \"%s\"\n", lle,
187 inet_ntoa(((const struct sockaddr_in *)l3addr)->sin_addr));
188 }
189 #endif
190 IF_AFDATA_UNLOCK(ifp);
191 CURVNET_RESTORE();
192 }
193
194 /*
195 * Broadcast an ARP request. Caller specifies:
196 * - arp header source ip address
197 * - arp header target ip address
198 * - arp header source ethernet address
199 */
200 void
201 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,
202 u_char *enaddr)
203 {
204 struct mbuf *m;
205 struct arphdr *ah;
206 struct sockaddr sa;
207
208 if (sip == NULL) {
209 /* XXX don't believe this can happen (or explain why) */
210 /*
211 * The caller did not supply a source address, try to find
212 * a compatible one among those assigned to this interface.
213 */
214 struct ifaddr *ifa;
215
216 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
217 if (!ifa->ifa_addr ||
218 ifa->ifa_addr->sa_family != AF_INET)
219 continue;
220 sip = &SIN(ifa->ifa_addr)->sin_addr;
221 if (0 == ((sip->s_addr ^ tip->s_addr) &
222 SIN(ifa->ifa_netmask)->sin_addr.s_addr) )
223 break; /* found it. */
224 }
225 if (sip == NULL) {
226 printf("%s: cannot find matching address\n", __func__);
227 return;
228 }
229 }
230
231 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
232 return;
233 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
234 2*ifp->if_data.ifi_addrlen;
235 m->m_pkthdr.len = m->m_len;
236 MH_ALIGN(m, m->m_len);
237 ah = mtod(m, struct arphdr *);
238 bzero((caddr_t)ah, m->m_len);
239 #ifdef MAC
240 mac_netinet_arp_send(ifp, m);
241 #endif
242 ah->ar_pro = htons(ETHERTYPE_IP);
243 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
244 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
245 ah->ar_op = htons(ARPOP_REQUEST);
246 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
247 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
248 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
249 sa.sa_family = AF_ARP;
250 sa.sa_len = 2;
251 m->m_flags |= M_BCAST;
252 (*ifp->if_output)(ifp, m, &sa, NULL);
253 ARPSTAT_INC(txrequests);
254 }
255
256 /*
257 * Resolve an IP address into an ethernet address.
258 * On input:
259 * ifp is the interface we use
260 * rt0 is the route to the final destination (possibly useless)
261 * m is the mbuf. May be NULL if we don't have a packet.
262 * dst is the next hop,
263 * desten is where we want the address.
264 *
265 * On success, desten is filled in and the function returns 0;
266 * If the packet must be held pending resolution, we return EWOULDBLOCK
267 * On other errors, we return the corresponding error code.
268 * Note that m_freem() handles NULL.
269 */
270 int
271 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
272 struct sockaddr *dst, u_char *desten, struct llentry **lle)
273 {
274 struct llentry *la = 0;
275 u_int flags = 0;
276 int error, renew;
277
278 *lle = NULL;
279 if (m != NULL) {
280 if (m->m_flags & M_BCAST) {
281 /* broadcast */
282 (void)memcpy(desten,
283 ifp->if_broadcastaddr, ifp->if_addrlen);
284 return (0);
285 }
286 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
287 /* multicast */
288 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
289 return (0);
290 }
291 }
292 /* XXXXX
293 */
294 retry:
295 IF_AFDATA_RLOCK(ifp);
296 la = lla_lookup(LLTABLE(ifp), flags, dst);
297 IF_AFDATA_RUNLOCK(ifp);
298 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
299 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
300 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
301 IF_AFDATA_WLOCK(ifp);
302 la = lla_lookup(LLTABLE(ifp), flags, dst);
303 IF_AFDATA_WUNLOCK(ifp);
304 }
305 if (la == NULL) {
306 if (flags & LLE_CREATE)
307 log(LOG_DEBUG,
308 "arpresolve: can't allocate llinfo for %s\n",
309 inet_ntoa(SIN(dst)->sin_addr));
310 m_freem(m);
311 return (EINVAL);
312 }
313
314 if ((la->la_flags & LLE_VALID) &&
315 ((la->la_flags & LLE_STATIC) || la->la_expire > time_second)) {
316 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
317 /*
318 * If entry has an expiry time and it is approaching,
319 * see if we need to send an ARP request within this
320 * arpt_down interval.
321 */
322 if (!(la->la_flags & LLE_STATIC) &&
323 time_second + la->la_preempt > la->la_expire) {
324 arprequest(ifp, NULL,
325 &SIN(dst)->sin_addr, IF_LLADDR(ifp));
326
327 la->la_preempt--;
328 }
329
330 *lle = la;
331 error = 0;
332 goto done;
333 }
334
335 if (la->la_flags & LLE_STATIC) { /* should not happen! */
336 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
337 inet_ntoa(SIN(dst)->sin_addr));
338 m_freem(m);
339 error = EINVAL;
340 goto done;
341 }
342
343 renew = (la->la_asked == 0 || la->la_expire != time_second);
344 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
345 flags |= LLE_EXCLUSIVE;
346 LLE_RUNLOCK(la);
347 goto retry;
348 }
349 /*
350 * There is an arptab entry, but no ethernet address
351 * response yet. Replace the held mbuf with this
352 * latest one.
353 */
354 if (m != NULL) {
355 if (la->la_hold != NULL) {
356 m_freem(la->la_hold);
357 ARPSTAT_INC(dropped);
358 }
359 la->la_hold = m;
360 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
361 flags &= ~LLE_EXCLUSIVE;
362 LLE_DOWNGRADE(la);
363 }
364
365 }
366 /*
367 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
368 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
369 * if we have already sent arp_maxtries ARP requests. Retransmit the
370 * ARP request, but not faster than one request per second.
371 */
372 if (la->la_asked < V_arp_maxtries)
373 error = EWOULDBLOCK; /* First request. */
374 else
375 error =
376 (rt0->rt_flags & RTF_GATEWAY) ? EHOSTUNREACH : EHOSTDOWN;
377
378 if (renew) {
379 LLE_ADDREF(la);
380 la->la_expire = time_second + V_arpt_down;
381 callout_reset(&la->la_timer, hz * V_arpt_down, arptimer, la);
382 la->la_asked++;
383 LLE_WUNLOCK(la);
384 arprequest(ifp, NULL, &SIN(dst)->sin_addr,
385 IF_LLADDR(ifp));
386 return (error);
387 }
388 done:
389 if (flags & LLE_EXCLUSIVE)
390 LLE_WUNLOCK(la);
391 else
392 LLE_RUNLOCK(la);
393 return (error);
394 }
395
396 /*
397 * Common length and type checks are done here,
398 * then the protocol-specific routine is called.
399 */
400 static void
401 arpintr(struct mbuf *m)
402 {
403 struct arphdr *ar;
404
405 if (m->m_len < sizeof(struct arphdr) &&
406 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
407 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
408 return;
409 }
410 ar = mtod(m, struct arphdr *);
411
412 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
413 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
414 ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
415 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
416 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
417 (unsigned char *)&ar->ar_hrd, "");
418 m_freem(m);
419 return;
420 }
421
422 if (m->m_len < arphdr_len(ar)) {
423 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
424 log(LOG_ERR, "arp: runt packet\n");
425 m_freem(m);
426 return;
427 }
428 ar = mtod(m, struct arphdr *);
429 }
430
431 ARPSTAT_INC(received);
432 switch (ntohs(ar->ar_pro)) {
433 #ifdef INET
434 case ETHERTYPE_IP:
435 in_arpinput(m);
436 return;
437 #endif
438 }
439 m_freem(m);
440 }
441
442 #ifdef INET
443 /*
444 * ARP for Internet protocols on 10 Mb/s Ethernet.
445 * Algorithm is that given in RFC 826.
446 * In addition, a sanity check is performed on the sender
447 * protocol address, to catch impersonators.
448 * We no longer handle negotiations for use of trailer protocol:
449 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
450 * along with IP replies if we wanted trailers sent to us,
451 * and also sent them in response to IP replies.
452 * This allowed either end to announce the desire to receive
453 * trailer packets.
454 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
455 * but formerly didn't normally send requests.
456 */
457 static int log_arp_wrong_iface = 1;
458 static int log_arp_movements = 1;
459 static int log_arp_permanent_modify = 1;
460
461 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
462 &log_arp_wrong_iface, 0,
463 "log arp packets arriving on the wrong interface");
464 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
465 &log_arp_movements, 0,
466 "log arp replies from MACs different than the one in the cache");
467 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
468 &log_arp_permanent_modify, 0,
469 "log arp replies from MACs different than the one in the permanent arp entry");
470
471
472 static void
473 in_arpinput(struct mbuf *m)
474 {
475 struct arphdr *ah;
476 struct ifnet *ifp = m->m_pkthdr.rcvif;
477 struct llentry *la = NULL;
478 struct rtentry *rt;
479 struct ifaddr *ifa;
480 struct in_ifaddr *ia;
481 struct mbuf *hold;
482 struct sockaddr sa;
483 struct in_addr isaddr, itaddr, myaddr;
484 u_int8_t *enaddr = NULL;
485 int op, flags;
486 int req_len;
487 int bridged = 0, is_bridge = 0;
488 #ifdef DEV_CARP
489 int carp_match = 0;
490 #endif
491 struct sockaddr_in sin;
492 sin.sin_len = sizeof(struct sockaddr_in);
493 sin.sin_family = AF_INET;
494 sin.sin_addr.s_addr = 0;
495
496 if (ifp->if_bridge)
497 bridged = 1;
498 if (ifp->if_type == IFT_BRIDGE)
499 is_bridge = 1;
500
501 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
502 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
503 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
504 return;
505 }
506
507 ah = mtod(m, struct arphdr *);
508 op = ntohs(ah->ar_op);
509 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
510 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
511
512 if (op == ARPOP_REPLY)
513 ARPSTAT_INC(rxreplies);
514
515 /*
516 * For a bridge, we want to check the address irrespective
517 * of the receive interface. (This will change slightly
518 * when we have clusters of interfaces).
519 * If the interface does not match, but the recieving interface
520 * is part of carp, we call carp_iamatch to see if this is a
521 * request for the virtual host ip.
522 * XXX: This is really ugly!
523 */
524 IN_IFADDR_RLOCK();
525 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
526 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
527 ia->ia_ifp == ifp) &&
528 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
529 ifa_ref(&ia->ia_ifa);
530 IN_IFADDR_RUNLOCK();
531 goto match;
532 }
533 #ifdef DEV_CARP
534 if (ifp->if_carp != NULL &&
535 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) &&
536 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
537 carp_match = 1;
538 ifa_ref(&ia->ia_ifa);
539 IN_IFADDR_RUNLOCK();
540 goto match;
541 }
542 #endif
543 }
544 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
545 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
546 ia->ia_ifp == ifp) &&
547 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
548 ifa_ref(&ia->ia_ifa);
549 IN_IFADDR_RUNLOCK();
550 goto match;
551 }
552
553 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
554 (ia->ia_ifp->if_bridge == ifp->if_softc && \
555 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
556 addr == ia->ia_addr.sin_addr.s_addr)
557 /*
558 * Check the case when bridge shares its MAC address with
559 * some of its children, so packets are claimed by bridge
560 * itself (bridge_input() does it first), but they are really
561 * meant to be destined to the bridge member.
562 */
563 if (is_bridge) {
564 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
565 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
566 ifa_ref(&ia->ia_ifa);
567 ifp = ia->ia_ifp;
568 IN_IFADDR_RUNLOCK();
569 goto match;
570 }
571 }
572 }
573 #undef BDG_MEMBER_MATCHES_ARP
574 IN_IFADDR_RUNLOCK();
575
576 /*
577 * No match, use the first inet address on the receive interface
578 * as a dummy address for the rest of the function.
579 */
580 IF_ADDR_LOCK(ifp);
581 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
582 if (ifa->ifa_addr->sa_family == AF_INET) {
583 ia = ifatoia(ifa);
584 ifa_ref(ifa);
585 IF_ADDR_UNLOCK(ifp);
586 goto match;
587 }
588 IF_ADDR_UNLOCK(ifp);
589
590 /*
591 * If bridging, fall back to using any inet address.
592 */
593 IN_IFADDR_RLOCK();
594 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
595 IN_IFADDR_RUNLOCK();
596 goto drop;
597 }
598 ifa_ref(&ia->ia_ifa);
599 IN_IFADDR_RUNLOCK();
600 match:
601 if (!enaddr)
602 enaddr = (u_int8_t *)IF_LLADDR(ifp);
603 myaddr = ia->ia_addr.sin_addr;
604 ifa_free(&ia->ia_ifa);
605 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
606 goto drop; /* it's from me, ignore it. */
607 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
608 log(LOG_ERR,
609 "arp: link address is broadcast for IP address %s!\n",
610 inet_ntoa(isaddr));
611 goto drop;
612 }
613 /*
614 * Warn if another host is using the same IP address, but only if the
615 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
616 * case we suppress the warning to avoid false positive complaints of
617 * potential misconfiguration.
618 */
619 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
620 log(LOG_ERR,
621 "arp: %*D is using my IP address %s on %s!\n",
622 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
623 inet_ntoa(isaddr), ifp->if_xname);
624 itaddr = myaddr;
625 ARPSTAT_INC(dupips);
626 goto reply;
627 }
628 if (ifp->if_flags & IFF_STATICARP)
629 goto reply;
630
631 bzero(&sin, sizeof(sin));
632 sin.sin_len = sizeof(struct sockaddr_in);
633 sin.sin_family = AF_INET;
634 sin.sin_addr = isaddr;
635 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
636 flags |= LLE_EXCLUSIVE;
637 IF_AFDATA_LOCK(ifp);
638 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
639 IF_AFDATA_UNLOCK(ifp);
640 if (la != NULL) {
641 /* the following is not an error when doing bridging */
642 if (!bridged && la->lle_tbl->llt_ifp != ifp
643 #ifdef DEV_CARP
644 && (ifp->if_type != IFT_CARP || !carp_match)
645 #endif
646 ) {
647 if (log_arp_wrong_iface)
648 log(LOG_ERR, "arp: %s is on %s "
649 "but got reply from %*D on %s\n",
650 inet_ntoa(isaddr),
651 la->lle_tbl->llt_ifp->if_xname,
652 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
653 ifp->if_xname);
654 LLE_WUNLOCK(la);
655 goto reply;
656 }
657 if ((la->la_flags & LLE_VALID) &&
658 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
659 if (la->la_flags & LLE_STATIC) {
660 LLE_WUNLOCK(la);
661 log(LOG_ERR,
662 "arp: %*D attempts to modify permanent "
663 "entry for %s on %s\n",
664 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
665 inet_ntoa(isaddr), ifp->if_xname);
666 goto reply;
667 }
668 if (log_arp_movements) {
669 log(LOG_INFO, "arp: %s moved from %*D "
670 "to %*D on %s\n",
671 inet_ntoa(isaddr),
672 ifp->if_addrlen,
673 (u_char *)&la->ll_addr, ":",
674 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
675 ifp->if_xname);
676 }
677 }
678
679 if (ifp->if_addrlen != ah->ar_hln) {
680 LLE_WUNLOCK(la);
681 log(LOG_WARNING,
682 "arp from %*D: addr len: new %d, i/f %d (ignored)",
683 ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
684 ah->ar_hln, ifp->if_addrlen);
685 goto reply;
686 }
687 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
688 la->la_flags |= LLE_VALID;
689
690 EVENTHANDLER_INVOKE(arp_update_event, la);
691
692 if (!(la->la_flags & LLE_STATIC)) {
693 la->la_expire = time_second + V_arpt_keep;
694 callout_reset(&la->la_timer, hz * V_arpt_keep,
695 arptimer, la);
696 }
697 la->la_asked = 0;
698 la->la_preempt = V_arp_maxtries;
699 hold = la->la_hold;
700 if (hold != NULL) {
701 la->la_hold = NULL;
702 memcpy(&sa, L3_ADDR(la), sizeof(sa));
703 }
704 LLE_WUNLOCK(la);
705 if (hold != NULL)
706 (*ifp->if_output)(ifp, hold, &sa, NULL);
707 }
708 reply:
709 if (op != ARPOP_REQUEST)
710 goto drop;
711 ARPSTAT_INC(rxrequests);
712
713 if (itaddr.s_addr == myaddr.s_addr) {
714 /* Shortcut.. the receiving interface is the target. */
715 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
716 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
717 } else {
718 struct llentry *lle = NULL;
719
720 sin.sin_addr = itaddr;
721 IF_AFDATA_LOCK(ifp);
722 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
723 IF_AFDATA_UNLOCK(ifp);
724
725 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
726 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
727 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
728 LLE_RUNLOCK(lle);
729 } else {
730
731 if (lle != NULL)
732 LLE_RUNLOCK(lle);
733
734 if (!V_arp_proxyall)
735 goto drop;
736
737 sin.sin_addr = itaddr;
738 /* XXX MRT use table 0 for arp reply */
739 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
740 if (!rt)
741 goto drop;
742
743 /*
744 * Don't send proxies for nodes on the same interface
745 * as this one came out of, or we'll get into a fight
746 * over who claims what Ether address.
747 */
748 if (!rt->rt_ifp || rt->rt_ifp == ifp) {
749 RTFREE_LOCKED(rt);
750 goto drop;
751 }
752 RTFREE_LOCKED(rt);
753
754 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
755 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
756
757 /*
758 * Also check that the node which sent the ARP packet
759 * is on the the interface we expect it to be on. This
760 * avoids ARP chaos if an interface is connected to the
761 * wrong network.
762 */
763 sin.sin_addr = isaddr;
764
765 /* XXX MRT use table 0 for arp checks */
766 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
767 if (!rt)
768 goto drop;
769 if (rt->rt_ifp != ifp) {
770 log(LOG_INFO, "arp_proxy: ignoring request"
771 " from %s via %s, expecting %s\n",
772 inet_ntoa(isaddr), ifp->if_xname,
773 rt->rt_ifp->if_xname);
774 RTFREE_LOCKED(rt);
775 goto drop;
776 }
777 RTFREE_LOCKED(rt);
778
779 #ifdef DEBUG_PROXY
780 printf("arp: proxying for %s\n",
781 inet_ntoa(itaddr));
782 #endif
783 }
784 }
785
786 if (itaddr.s_addr == myaddr.s_addr &&
787 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
788 /* RFC 3927 link-local IPv4; always reply by broadcast. */
789 #ifdef DEBUG_LINKLOCAL
790 printf("arp: sending reply for link-local addr %s\n",
791 inet_ntoa(itaddr));
792 #endif
793 m->m_flags |= M_BCAST;
794 m->m_flags &= ~M_MCAST;
795 } else {
796 /* default behaviour; never reply by broadcast. */
797 m->m_flags &= ~(M_BCAST|M_MCAST);
798 }
799 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
800 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
801 ah->ar_op = htons(ARPOP_REPLY);
802 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
803 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
804 m->m_pkthdr.len = m->m_len;
805 sa.sa_family = AF_ARP;
806 sa.sa_len = 2;
807 (*ifp->if_output)(ifp, m, &sa, NULL);
808 ARPSTAT_INC(txreplies);
809 return;
810
811 drop:
812 m_freem(m);
813 }
814 #endif
815
816 void
817 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
818 {
819 struct llentry *lle;
820
821 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
822 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
823 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
824 /*
825 * interface address is considered static entry
826 * because the output of the arp utility shows
827 * that L2 entry as permanent
828 */
829 IF_AFDATA_LOCK(ifp);
830 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
831 (struct sockaddr *)IA_SIN(ifa));
832 IF_AFDATA_UNLOCK(ifp);
833 if (lle == NULL)
834 log(LOG_INFO, "arp_ifinit: cannot create arp "
835 "entry for interface address\n");
836 else
837 LLE_RUNLOCK(lle);
838 }
839 ifa->ifa_rtrequest = NULL;
840 }
841
842 void
843 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
844 {
845 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
846 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
847 &IA_SIN(ifa)->sin_addr, enaddr);
848 ifa->ifa_rtrequest = NULL;
849 }
850
851 static void
852 arp_init(void)
853 {
854
855 netisr_register(&arp_nh);
856 }
857 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);
Cache object: 035daf8183bf1e5f780cb3d5e1d31f12
|