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 195727 2009-07-16 21:13:04Z rwatson $");
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#include <sys/vimage.h>
55
56#include <net/if.h>
57#include <net/if_dl.h>
58#include <net/if_types.h>
59#include <net/netisr.h>
60#include <net/if_llc.h>
61#include <net/ethernet.h>
62#include <net/route.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
81SYSCTL_DECL(_net_link_ether);
82SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
83
84/* timer values */
85static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20
86 * minutes */
87static VNET_DEFINE(int, arp_maxtries) = 5;
88static VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for
89 * local traffic */
90static VNET_DEFINE(int, arp_proxyall);
91
92#define V_arpt_keep VNET(arpt_keep)
93#define V_arp_maxtries VNET(arp_maxtries)
94#define V_useloopback VNET(useloopback)
95#define V_arp_proxyall VNET(arp_proxyall)
96
97SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
98 &VNET_NAME(arpt_keep), 0,
99 "ARP entry lifetime in seconds");
100
101SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
102 &VNET_NAME(arp_maxtries), 0,
103 "ARP resolution attempts before returning error");
104SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
105 &VNET_NAME(useloopback), 0,
106 "Use the loopback interface for local traffic");
107SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
108 &VNET_NAME(arp_proxyall), 0,
109 "Enable proxy ARP for all suitable requests");
110
111static void arp_init(void);
112void arprequest(struct ifnet *,
113 struct in_addr *, struct in_addr *, u_char *);
114static void arpintr(struct mbuf *);
115static void arptimer(void *);
116#ifdef INET
117static void in_arpinput(struct mbuf *);
118#endif
119
120static const struct netisr_handler arp_nh = {
121 .nh_name = "arp",
122 .nh_handler = arpintr,
123 .nh_proto = NETISR_ARP,
124 .nh_policy = NETISR_POLICY_SOURCE,
125};
126
127#ifdef AF_INET
128void arp_ifscrub(struct ifnet *ifp, uint32_t addr);
129
130/*
131 * called by in_ifscrub to remove entry from the table when
132 * the interface goes away
133 */
134void
135arp_ifscrub(struct ifnet *ifp, uint32_t addr)
136{
137 struct sockaddr_in addr4;
138
139 bzero((void *)&addr4, sizeof(addr4));
140 addr4.sin_len = sizeof(addr4);
141 addr4.sin_family = AF_INET;
142 addr4.sin_addr.s_addr = addr;
143 CURVNET_SET(ifp->if_vnet);
144 IF_AFDATA_LOCK(ifp);
145 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
146 (struct sockaddr *)&addr4);
147 IF_AFDATA_UNLOCK(ifp);
148 CURVNET_RESTORE();
149}
150#endif
151
152/*
153 * Timeout routine. Age arp_tab entries periodically.
154 */
155static void
156arptimer(void *arg)
157{
158 struct ifnet *ifp;
159 struct llentry *lle = (struct llentry *)arg;
160
161 if (lle == NULL) {
162 panic("%s: NULL entry!\n", __func__);
163 return;
164 }
165 ifp = lle->lle_tbl->llt_ifp;
166 IF_AFDATA_LOCK(ifp);
167 LLE_WLOCK(lle);
168 if (((lle->la_flags & LLE_DELETED)
169 || (time_second >= lle->la_expire))
170 && (!callout_pending(&lle->la_timer) &&
171 callout_active(&lle->la_timer)))
172 (void) llentry_free(lle);
173 else {
174 /*
175 * Still valid, just drop our reference
176 */
177 LLE_FREE_LOCKED(lle);
178 }
179 IF_AFDATA_UNLOCK(ifp);
180}
181
182/*
183 * Broadcast an ARP request. Caller specifies:
184 * - arp header source ip address
185 * - arp header target ip address
186 * - arp header source ethernet address
187 */
188void
189arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,
190 u_char *enaddr)
191{
192 struct mbuf *m;
193 struct arphdr *ah;
194 struct sockaddr sa;
195
196 if (sip == NULL) {
197 /* XXX don't believe this can happen (or explain why) */
198 /*
199 * The caller did not supply a source address, try to find
200 * a compatible one among those assigned to this interface.
201 */
202 struct ifaddr *ifa;
203
204 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
205 if (!ifa->ifa_addr ||
206 ifa->ifa_addr->sa_family != AF_INET)
207 continue;
208 sip = &SIN(ifa->ifa_addr)->sin_addr;
209 if (0 == ((sip->s_addr ^ tip->s_addr) &
210 SIN(ifa->ifa_netmask)->sin_addr.s_addr) )
211 break; /* found it. */
212 }
213 if (sip == NULL) {
214 printf("%s: cannot find matching address\n", __func__);
215 return;
216 }
217 }
218
219 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
220 return;
221 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
222 2*ifp->if_data.ifi_addrlen;
223 m->m_pkthdr.len = m->m_len;
224 MH_ALIGN(m, m->m_len);
225 ah = mtod(m, struct arphdr *);
226 bzero((caddr_t)ah, m->m_len);
227#ifdef MAC
228 mac_netinet_arp_send(ifp, m);
229#endif
230 ah->ar_pro = htons(ETHERTYPE_IP);
231 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
232 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
233 ah->ar_op = htons(ARPOP_REQUEST);
234 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
235 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
236 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
237 sa.sa_family = AF_ARP;
238 sa.sa_len = 2;
239 m->m_flags |= M_BCAST;
240 (*ifp->if_output)(ifp, m, &sa, NULL);
241}
242
243/*
244 * Resolve an IP address into an ethernet address.
245 * On input:
246 * ifp is the interface we use
247 * rt0 is the route to the final destination (possibly useless)
248 * m is the mbuf. May be NULL if we don't have a packet.
249 * dst is the next hop,
250 * desten is where we want the address.
251 *
252 * On success, desten is filled in and the function returns 0;
253 * If the packet must be held pending resolution, we return EWOULDBLOCK
254 * On other errors, we return the corresponding error code.
255 * Note that m_freem() handles NULL.
256 */
257int
258arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
259 struct sockaddr *dst, u_char *desten, struct llentry **lle)
260{
261 struct llentry *la = 0;
262 u_int flags = 0;
263 int error, renew;
264
265 *lle = NULL;
266 if (m != NULL) {
267 if (m->m_flags & M_BCAST) {
268 /* broadcast */
269 (void)memcpy(desten,
270 ifp->if_broadcastaddr, ifp->if_addrlen);
271 return (0);
272 }
273 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
274 /* multicast */
275 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
276 return (0);
277 }
278 }
279 /* XXXXX
280 */
281retry:
282 IF_AFDATA_RLOCK(ifp);
283 la = lla_lookup(LLTABLE(ifp), flags, dst);
284 IF_AFDATA_RUNLOCK(ifp);
285 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
286 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
287 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
288 IF_AFDATA_WLOCK(ifp);
289 la = lla_lookup(LLTABLE(ifp), flags, dst);
290 IF_AFDATA_WUNLOCK(ifp);
291 }
292 if (la == NULL) {
293 if (flags & LLE_CREATE)
294 log(LOG_DEBUG,
295 "arpresolve: can't allocate llinfo for %s\n",
296 inet_ntoa(SIN(dst)->sin_addr));
297 m_freem(m);
298 return (EINVAL);
299 }
300
301 if ((la->la_flags & LLE_VALID) &&
302 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
303 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
304 /*
305 * If entry has an expiry time and it is approaching,
306 * see if we need to send an ARP request within this
307 * arpt_down interval.
308 */
309 if (!(la->la_flags & LLE_STATIC) &&
310 time_uptime + la->la_preempt > la->la_expire) {
311 arprequest(ifp, NULL,
312 &SIN(dst)->sin_addr, IF_LLADDR(ifp));
313
314 la->la_preempt--;
315 }
316
317 *lle = la;
318 error = 0;
319 goto done;
320 }
321
322 if (la->la_flags & LLE_STATIC) { /* should not happen! */
323 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
324 inet_ntoa(SIN(dst)->sin_addr));
325 m_freem(m);
326 error = EINVAL;
327 goto done;
328 }
329
330 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
331 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
332 flags |= LLE_EXCLUSIVE;
333 LLE_RUNLOCK(la);
334 goto retry;
335 }
336 /*
337 * There is an arptab entry, but no ethernet address
338 * response yet. Replace the held mbuf with this
339 * latest one.
340 */
341 if (m != NULL) {
342 if (la->la_hold != NULL)
343 m_freem(la->la_hold);
344 la->la_hold = m;
345 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
346 flags &= ~LLE_EXCLUSIVE;
347 LLE_DOWNGRADE(la);
348 }
349
350 }
351 /*
352 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
353 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
354 * if we have already sent arp_maxtries ARP requests. Retransmit the
355 * ARP request, but not faster than one request per second.
356 */
357 if (la->la_asked < V_arp_maxtries)
358 error = EWOULDBLOCK; /* First request. */
359 else
360 error =
361 (rt0->rt_flags & RTF_GATEWAY) ? EHOSTDOWN : EHOSTUNREACH;
362
363 if (renew) {
364 LLE_ADDREF(la);
365 la->la_expire = time_uptime;
366 callout_reset(&la->la_timer, hz, arptimer, la);
367 la->la_asked++;
368 LLE_WUNLOCK(la);
369 arprequest(ifp, NULL, &SIN(dst)->sin_addr,
370 IF_LLADDR(ifp));
371 return (error);
372 }
373done:
374 if (flags & LLE_EXCLUSIVE)
375 LLE_WUNLOCK(la);
376 else
377 LLE_RUNLOCK(la);
378 return (error);
379}
380
381/*
382 * Common length and type checks are done here,
383 * then the protocol-specific routine is called.
384 */
385static void
386arpintr(struct mbuf *m)
387{
388 struct arphdr *ar;
389
390 if (m->m_len < sizeof(struct arphdr) &&
391 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
392 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
393 return;
394 }
395 ar = mtod(m, struct arphdr *);
396
397 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
398 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
399 ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
400 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
401 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
402 (unsigned char *)&ar->ar_hrd, "");
403 m_freem(m);
404 return;
405 }
406
407 if (m->m_len < arphdr_len(ar)) {
408 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
409 log(LOG_ERR, "arp: runt packet\n");
410 m_freem(m);
411 return;
412 }
413 ar = mtod(m, struct arphdr *);
414 }
415
416 switch (ntohs(ar->ar_pro)) {
417#ifdef INET
418 case ETHERTYPE_IP:
419 in_arpinput(m);
420 return;
421#endif
422 }
423 m_freem(m);
424}
425
426#ifdef INET
427/*
428 * ARP for Internet protocols on 10 Mb/s Ethernet.
429 * Algorithm is that given in RFC 826.
430 * In addition, a sanity check is performed on the sender
431 * protocol address, to catch impersonators.
432 * We no longer handle negotiations for use of trailer protocol:
433 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
434 * along with IP replies if we wanted trailers sent to us,
435 * and also sent them in response to IP replies.
436 * This allowed either end to announce the desire to receive
437 * trailer packets.
438 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
439 * but formerly didn't normally send requests.
440 */
441static int log_arp_wrong_iface = 1;
442static int log_arp_movements = 1;
443static int log_arp_permanent_modify = 1;
444
445SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
446 &log_arp_wrong_iface, 0,
447 "log arp packets arriving on the wrong interface");
448SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
449 &log_arp_movements, 0,
450 "log arp replies from MACs different than the one in the cache");
451SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
452 &log_arp_permanent_modify, 0,
453 "log arp replies from MACs different than the one in the permanent arp entry");
454
455
456static void
457in_arpinput(struct mbuf *m)
458{
459 struct arphdr *ah;
460 struct ifnet *ifp = m->m_pkthdr.rcvif;
461 struct llentry *la = NULL;
462 struct rtentry *rt;
463 struct ifaddr *ifa;
464 struct in_ifaddr *ia;
465 struct sockaddr sa;
466 struct in_addr isaddr, itaddr, myaddr;
467 u_int8_t *enaddr = NULL;
468 int op, flags;
469 struct mbuf *m0;
470 int req_len;
471 int bridged = 0, is_bridge = 0;
472#ifdef DEV_CARP
473 int carp_match = 0;
474#endif
475 struct sockaddr_in sin;
476 sin.sin_len = sizeof(struct sockaddr_in);
477 sin.sin_family = AF_INET;
478 sin.sin_addr.s_addr = 0;
479
480 if (ifp->if_bridge)
481 bridged = 1;
482 if (ifp->if_type == IFT_BRIDGE)
483 is_bridge = 1;
484
485 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
486 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
487 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
488 return;
489 }
490
491 ah = mtod(m, struct arphdr *);
492 op = ntohs(ah->ar_op);
493 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
494 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
495
496 /*
497 * For a bridge, we want to check the address irrespective
498 * of the receive interface. (This will change slightly
499 * when we have clusters of interfaces).
500 * If the interface does not match, but the recieving interface
501 * is part of carp, we call carp_iamatch to see if this is a
502 * request for the virtual host ip.
503 * XXX: This is really ugly!
504 */
505 IN_IFADDR_RLOCK();
506 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
507 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
508 ia->ia_ifp == ifp) &&
509 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
510 ifa_ref(&ia->ia_ifa);
511 IN_IFADDR_RUNLOCK();
512 goto match;
513 }
514#ifdef DEV_CARP
515 if (ifp->if_carp != NULL &&
516 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) &&
517 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
518 carp_match = 1;
519 ifa_ref(&ia->ia_ifa);
520 IN_IFADDR_RUNLOCK();
521 goto match;
522 }
523#endif
524 }
525 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
526 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
527 ia->ia_ifp == ifp) &&
528 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
529 ifa_ref(&ia->ia_ifa);
530 IN_IFADDR_RUNLOCK();
531 goto match;
532 }
533
534#define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
535 (ia->ia_ifp->if_bridge == ifp->if_softc && \
536 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
537 addr == ia->ia_addr.sin_addr.s_addr)
538 /*
539 * Check the case when bridge shares its MAC address with
540 * some of its children, so packets are claimed by bridge
541 * itself (bridge_input() does it first), but they are really
542 * meant to be destined to the bridge member.
543 */
544 if (is_bridge) {
545 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
546 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
547 ifa_ref(&ia->ia_ifa);
548 ifp = ia->ia_ifp;
549 IN_IFADDR_RUNLOCK();
550 goto match;
551 }
552 }
553 }
554#undef BDG_MEMBER_MATCHES_ARP
555 IN_IFADDR_RUNLOCK();
556
557 /*
558 * No match, use the first inet address on the receive interface
559 * as a dummy address for the rest of the function.
560 */
561 IF_ADDR_LOCK(ifp);
562 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
563 if (ifa->ifa_addr->sa_family == AF_INET) {
564 ia = ifatoia(ifa);
565 ifa_ref(ifa);
566 IF_ADDR_UNLOCK(ifp);
567 goto match;
568 }
569 IF_ADDR_UNLOCK(ifp);
570
571 /*
572 * If bridging, fall back to using any inet address.
573 */
574 IN_IFADDR_RLOCK();
575 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
576 IN_IFADDR_RUNLOCK();
577 goto drop;
578 }
579 ifa_ref(&ia->ia_ifa);
580 IN_IFADDR_RUNLOCK();
581match:
582 if (!enaddr)
583 enaddr = (u_int8_t *)IF_LLADDR(ifp);
584 myaddr = ia->ia_addr.sin_addr;
585 ifa_free(&ia->ia_ifa);
586 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
587 goto drop; /* it's from me, ignore it. */
588 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
589 log(LOG_ERR,
590 "arp: link address is broadcast for IP address %s!\n",
591 inet_ntoa(isaddr));
592 goto drop;
593 }
594 /*
595 * Warn if another host is using the same IP address, but only if the
596 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
597 * case we suppress the warning to avoid false positive complaints of
598 * potential misconfiguration.
599 */
600 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
601 log(LOG_ERR,
602 "arp: %*D is using my IP address %s on %s!\n",
603 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
604 inet_ntoa(isaddr), ifp->if_xname);
605 itaddr = myaddr;
606 goto reply;
607 }
608 if (ifp->if_flags & IFF_STATICARP)
609 goto reply;
610
611 bzero(&sin, sizeof(sin));
612 sin.sin_len = sizeof(struct sockaddr_in);
613 sin.sin_family = AF_INET;
614 sin.sin_addr = isaddr;
615 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
616 flags |= LLE_EXCLUSIVE;
617 IF_AFDATA_LOCK(ifp);
618 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
619 IF_AFDATA_UNLOCK(ifp);
620 if (la != NULL) {
621 /* the following is not an error when doing bridging */
622 if (!bridged && la->lle_tbl->llt_ifp != ifp
623#ifdef DEV_CARP
624 && (ifp->if_type != IFT_CARP || !carp_match)
625#endif
626 ) {
627 if (log_arp_wrong_iface)
628 log(LOG_ERR, "arp: %s is on %s "
629 "but got reply from %*D on %s\n",
630 inet_ntoa(isaddr),
631 la->lle_tbl->llt_ifp->if_xname,
632 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
633 ifp->if_xname);
634 goto reply;
635 }
636 if ((la->la_flags & LLE_VALID) &&
637 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
638 if (la->la_flags & LLE_STATIC) {
639 log(LOG_ERR,
640 "arp: %*D attempts to modify permanent "
641 "entry for %s on %s\n",
642 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
643 inet_ntoa(isaddr), ifp->if_xname);
644 goto reply;
645 }
646 if (log_arp_movements) {
647 log(LOG_INFO, "arp: %s moved from %*D "
648 "to %*D on %s\n",
649 inet_ntoa(isaddr),
650 ifp->if_addrlen,
651 (u_char *)&la->ll_addr, ":",
652 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
653 ifp->if_xname);
654 }
655 }
656
657 if (ifp->if_addrlen != ah->ar_hln) {
658 log(LOG_WARNING,
659 "arp from %*D: addr len: new %d, i/f %d (ignored)",
660 ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
661 ah->ar_hln, ifp->if_addrlen);
662 goto reply;
663 }
664 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
665 la->la_flags |= LLE_VALID;
666
667 if (!(la->la_flags & LLE_STATIC)) {
668 la->la_expire = time_uptime + V_arpt_keep;
669 callout_reset(&la->la_timer, hz * V_arpt_keep,
670 arptimer, la);
671 }
672 la->la_asked = 0;
673 la->la_preempt = V_arp_maxtries;
674 if (la->la_hold != NULL) {
675 m0 = la->la_hold;
676 la->la_hold = 0;
677 memcpy(&sa, L3_ADDR(la), sizeof(sa));
678 LLE_WUNLOCK(la);
679
680 (*ifp->if_output)(ifp, m0, &sa, NULL);
681 return;
682 }
683 }
684reply:
685 if (op != ARPOP_REQUEST)
686 goto drop;
687
688 if (itaddr.s_addr == myaddr.s_addr) {
689 /* Shortcut.. the receiving interface is the target. */
690 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
691 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
692 } else {
693 struct llentry *lle = NULL;
694
695 if (!V_arp_proxyall)
696 goto drop;
697
698 sin.sin_addr = itaddr;
699 /* XXX MRT use table 0 for arp reply */
700 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
701 if (!rt)
702 goto drop;
703
704 /*
705 * Don't send proxies for nodes on the same interface
706 * as this one came out of, or we'll get into a fight
707 * over who claims what Ether address.
708 */
709 if (!rt->rt_ifp || rt->rt_ifp == ifp) {
710 RTFREE_LOCKED(rt);
711 goto drop;
712 }
713 IF_AFDATA_LOCK(rt->rt_ifp);
714 lle = lla_lookup(LLTABLE(rt->rt_ifp), 0, (struct sockaddr *)&sin);
715 IF_AFDATA_UNLOCK(rt->rt_ifp);
716 RTFREE_LOCKED(rt);
717
718 if (lle != NULL) {
719 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
720 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
721 LLE_RUNLOCK(lle);
722 } else
723 goto drop;
724
725 /*
726 * Also check that the node which sent the ARP packet
727 * is on the the interface we expect it to be on. This
728 * avoids ARP chaos if an interface is connected to the
729 * wrong network.
730 */
731 sin.sin_addr = isaddr;
732
733 /* XXX MRT use table 0 for arp checks */
734 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
735 if (!rt)
736 goto drop;
737 if (rt->rt_ifp != ifp) {
738 log(LOG_INFO, "arp_proxy: ignoring request"
739 " from %s via %s, expecting %s\n",
740 inet_ntoa(isaddr), ifp->if_xname,
741 rt->rt_ifp->if_xname);
742 RTFREE_LOCKED(rt);
743 goto drop;
744 }
745 RTFREE_LOCKED(rt);
746
747#ifdef DEBUG_PROXY
748 printf("arp: proxying for %s\n",
749 inet_ntoa(itaddr));
750#endif
751 }
752
753 if (la != NULL)
754 LLE_WUNLOCK(la);
755 if (itaddr.s_addr == myaddr.s_addr &&
756 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
757 /* RFC 3927 link-local IPv4; always reply by broadcast. */
758#ifdef DEBUG_LINKLOCAL
759 printf("arp: sending reply for link-local addr %s\n",
760 inet_ntoa(itaddr));
761#endif
762 m->m_flags |= M_BCAST;
763 m->m_flags &= ~M_MCAST;
764 } else {
765 /* default behaviour; never reply by broadcast. */
766 m->m_flags &= ~(M_BCAST|M_MCAST);
767 }
768 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
769 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
770 ah->ar_op = htons(ARPOP_REPLY);
771 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
772 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
773 m->m_pkthdr.len = m->m_len;
774 sa.sa_family = AF_ARP;
775 sa.sa_len = 2;
776 (*ifp->if_output)(ifp, m, &sa, NULL);
777 return;
778
779drop:
780 if (la != NULL)
781 LLE_WUNLOCK(la);
782 m_freem(m);
783}
784#endif
785
786void
787arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
788{
789 struct llentry *lle;
790
791 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
792 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
793 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
794 /*
795 * interface address is considered static entry
796 * because the output of the arp utility shows
797 * that L2 entry as permanent
798 */
799 IF_AFDATA_LOCK(ifp);
800 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
801 (struct sockaddr *)IA_SIN(ifa));
802 IF_AFDATA_UNLOCK(ifp);
803 if (lle == NULL)
804 log(LOG_INFO, "arp_ifinit: cannot create arp "
805 "entry for interface address\n");
806 else
807 LLE_RUNLOCK(lle);
808 }
809 ifa->ifa_rtrequest = NULL;
810}
811
812void
813arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
814{
815 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
816 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
817 &IA_SIN(ifa)->sin_addr, enaddr);
818 ifa->ifa_rtrequest = NULL;
819}
820
821static void
822arp_init(void)
823{
824
825 netisr_register(&arp_nh);
826}
827SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);
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 195727 2009-07-16 21:13:04Z rwatson $");
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#include <sys/vimage.h>
55
56#include <net/if.h>
57#include <net/if_dl.h>
58#include <net/if_types.h>
59#include <net/netisr.h>
60#include <net/if_llc.h>
61#include <net/ethernet.h>
62#include <net/route.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
81SYSCTL_DECL(_net_link_ether);
82SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
83
84/* timer values */
85static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20
86 * minutes */
87static VNET_DEFINE(int, arp_maxtries) = 5;
88static VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for
89 * local traffic */
90static VNET_DEFINE(int, arp_proxyall);
91
92#define V_arpt_keep VNET(arpt_keep)
93#define V_arp_maxtries VNET(arp_maxtries)
94#define V_useloopback VNET(useloopback)
95#define V_arp_proxyall VNET(arp_proxyall)
96
97SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
98 &VNET_NAME(arpt_keep), 0,
99 "ARP entry lifetime in seconds");
100
101SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
102 &VNET_NAME(arp_maxtries), 0,
103 "ARP resolution attempts before returning error");
104SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
105 &VNET_NAME(useloopback), 0,
106 "Use the loopback interface for local traffic");
107SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
108 &VNET_NAME(arp_proxyall), 0,
109 "Enable proxy ARP for all suitable requests");
110
111static void arp_init(void);
112void arprequest(struct ifnet *,
113 struct in_addr *, struct in_addr *, u_char *);
114static void arpintr(struct mbuf *);
115static void arptimer(void *);
116#ifdef INET
117static void in_arpinput(struct mbuf *);
118#endif
119
120static const struct netisr_handler arp_nh = {
121 .nh_name = "arp",
122 .nh_handler = arpintr,
123 .nh_proto = NETISR_ARP,
124 .nh_policy = NETISR_POLICY_SOURCE,
125};
126
127#ifdef AF_INET
128void arp_ifscrub(struct ifnet *ifp, uint32_t addr);
129
130/*
131 * called by in_ifscrub to remove entry from the table when
132 * the interface goes away
133 */
134void
135arp_ifscrub(struct ifnet *ifp, uint32_t addr)
136{
137 struct sockaddr_in addr4;
138
139 bzero((void *)&addr4, sizeof(addr4));
140 addr4.sin_len = sizeof(addr4);
141 addr4.sin_family = AF_INET;
142 addr4.sin_addr.s_addr = addr;
143 CURVNET_SET(ifp->if_vnet);
144 IF_AFDATA_LOCK(ifp);
145 lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
146 (struct sockaddr *)&addr4);
147 IF_AFDATA_UNLOCK(ifp);
148 CURVNET_RESTORE();
149}
150#endif
151
152/*
153 * Timeout routine. Age arp_tab entries periodically.
154 */
155static void
156arptimer(void *arg)
157{
158 struct ifnet *ifp;
159 struct llentry *lle = (struct llentry *)arg;
160
161 if (lle == NULL) {
162 panic("%s: NULL entry!\n", __func__);
163 return;
164 }
165 ifp = lle->lle_tbl->llt_ifp;
166 IF_AFDATA_LOCK(ifp);
167 LLE_WLOCK(lle);
168 if (((lle->la_flags & LLE_DELETED)
169 || (time_second >= lle->la_expire))
170 && (!callout_pending(&lle->la_timer) &&
171 callout_active(&lle->la_timer)))
172 (void) llentry_free(lle);
173 else {
174 /*
175 * Still valid, just drop our reference
176 */
177 LLE_FREE_LOCKED(lle);
178 }
179 IF_AFDATA_UNLOCK(ifp);
180}
181
182/*
183 * Broadcast an ARP request. Caller specifies:
184 * - arp header source ip address
185 * - arp header target ip address
186 * - arp header source ethernet address
187 */
188void
189arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,
190 u_char *enaddr)
191{
192 struct mbuf *m;
193 struct arphdr *ah;
194 struct sockaddr sa;
195
196 if (sip == NULL) {
197 /* XXX don't believe this can happen (or explain why) */
198 /*
199 * The caller did not supply a source address, try to find
200 * a compatible one among those assigned to this interface.
201 */
202 struct ifaddr *ifa;
203
204 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
205 if (!ifa->ifa_addr ||
206 ifa->ifa_addr->sa_family != AF_INET)
207 continue;
208 sip = &SIN(ifa->ifa_addr)->sin_addr;
209 if (0 == ((sip->s_addr ^ tip->s_addr) &
210 SIN(ifa->ifa_netmask)->sin_addr.s_addr) )
211 break; /* found it. */
212 }
213 if (sip == NULL) {
214 printf("%s: cannot find matching address\n", __func__);
215 return;
216 }
217 }
218
219 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
220 return;
221 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
222 2*ifp->if_data.ifi_addrlen;
223 m->m_pkthdr.len = m->m_len;
224 MH_ALIGN(m, m->m_len);
225 ah = mtod(m, struct arphdr *);
226 bzero((caddr_t)ah, m->m_len);
227#ifdef MAC
228 mac_netinet_arp_send(ifp, m);
229#endif
230 ah->ar_pro = htons(ETHERTYPE_IP);
231 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
232 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
233 ah->ar_op = htons(ARPOP_REQUEST);
234 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
235 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
236 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
237 sa.sa_family = AF_ARP;
238 sa.sa_len = 2;
239 m->m_flags |= M_BCAST;
240 (*ifp->if_output)(ifp, m, &sa, NULL);
241}
242
243/*
244 * Resolve an IP address into an ethernet address.
245 * On input:
246 * ifp is the interface we use
247 * rt0 is the route to the final destination (possibly useless)
248 * m is the mbuf. May be NULL if we don't have a packet.
249 * dst is the next hop,
250 * desten is where we want the address.
251 *
252 * On success, desten is filled in and the function returns 0;
253 * If the packet must be held pending resolution, we return EWOULDBLOCK
254 * On other errors, we return the corresponding error code.
255 * Note that m_freem() handles NULL.
256 */
257int
258arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
259 struct sockaddr *dst, u_char *desten, struct llentry **lle)
260{
261 struct llentry *la = 0;
262 u_int flags = 0;
263 int error, renew;
264
265 *lle = NULL;
266 if (m != NULL) {
267 if (m->m_flags & M_BCAST) {
268 /* broadcast */
269 (void)memcpy(desten,
270 ifp->if_broadcastaddr, ifp->if_addrlen);
271 return (0);
272 }
273 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
274 /* multicast */
275 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
276 return (0);
277 }
278 }
279 /* XXXXX
280 */
281retry:
282 IF_AFDATA_RLOCK(ifp);
283 la = lla_lookup(LLTABLE(ifp), flags, dst);
284 IF_AFDATA_RUNLOCK(ifp);
285 if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
286 && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
287 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
288 IF_AFDATA_WLOCK(ifp);
289 la = lla_lookup(LLTABLE(ifp), flags, dst);
290 IF_AFDATA_WUNLOCK(ifp);
291 }
292 if (la == NULL) {
293 if (flags & LLE_CREATE)
294 log(LOG_DEBUG,
295 "arpresolve: can't allocate llinfo for %s\n",
296 inet_ntoa(SIN(dst)->sin_addr));
297 m_freem(m);
298 return (EINVAL);
299 }
300
301 if ((la->la_flags & LLE_VALID) &&
302 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
303 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
304 /*
305 * If entry has an expiry time and it is approaching,
306 * see if we need to send an ARP request within this
307 * arpt_down interval.
308 */
309 if (!(la->la_flags & LLE_STATIC) &&
310 time_uptime + la->la_preempt > la->la_expire) {
311 arprequest(ifp, NULL,
312 &SIN(dst)->sin_addr, IF_LLADDR(ifp));
313
314 la->la_preempt--;
315 }
316
317 *lle = la;
318 error = 0;
319 goto done;
320 }
321
322 if (la->la_flags & LLE_STATIC) { /* should not happen! */
323 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
324 inet_ntoa(SIN(dst)->sin_addr));
325 m_freem(m);
326 error = EINVAL;
327 goto done;
328 }
329
330 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
331 if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
332 flags |= LLE_EXCLUSIVE;
333 LLE_RUNLOCK(la);
334 goto retry;
335 }
336 /*
337 * There is an arptab entry, but no ethernet address
338 * response yet. Replace the held mbuf with this
339 * latest one.
340 */
341 if (m != NULL) {
342 if (la->la_hold != NULL)
343 m_freem(la->la_hold);
344 la->la_hold = m;
345 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
346 flags &= ~LLE_EXCLUSIVE;
347 LLE_DOWNGRADE(la);
348 }
349
350 }
351 /*
352 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
353 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
354 * if we have already sent arp_maxtries ARP requests. Retransmit the
355 * ARP request, but not faster than one request per second.
356 */
357 if (la->la_asked < V_arp_maxtries)
358 error = EWOULDBLOCK; /* First request. */
359 else
360 error =
361 (rt0->rt_flags & RTF_GATEWAY) ? EHOSTDOWN : EHOSTUNREACH;
362
363 if (renew) {
364 LLE_ADDREF(la);
365 la->la_expire = time_uptime;
366 callout_reset(&la->la_timer, hz, arptimer, la);
367 la->la_asked++;
368 LLE_WUNLOCK(la);
369 arprequest(ifp, NULL, &SIN(dst)->sin_addr,
370 IF_LLADDR(ifp));
371 return (error);
372 }
373done:
374 if (flags & LLE_EXCLUSIVE)
375 LLE_WUNLOCK(la);
376 else
377 LLE_RUNLOCK(la);
378 return (error);
379}
380
381/*
382 * Common length and type checks are done here,
383 * then the protocol-specific routine is called.
384 */
385static void
386arpintr(struct mbuf *m)
387{
388 struct arphdr *ar;
389
390 if (m->m_len < sizeof(struct arphdr) &&
391 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
392 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
393 return;
394 }
395 ar = mtod(m, struct arphdr *);
396
397 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
398 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
399 ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
400 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
401 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
402 (unsigned char *)&ar->ar_hrd, "");
403 m_freem(m);
404 return;
405 }
406
407 if (m->m_len < arphdr_len(ar)) {
408 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
409 log(LOG_ERR, "arp: runt packet\n");
410 m_freem(m);
411 return;
412 }
413 ar = mtod(m, struct arphdr *);
414 }
415
416 switch (ntohs(ar->ar_pro)) {
417#ifdef INET
418 case ETHERTYPE_IP:
419 in_arpinput(m);
420 return;
421#endif
422 }
423 m_freem(m);
424}
425
426#ifdef INET
427/*
428 * ARP for Internet protocols on 10 Mb/s Ethernet.
429 * Algorithm is that given in RFC 826.
430 * In addition, a sanity check is performed on the sender
431 * protocol address, to catch impersonators.
432 * We no longer handle negotiations for use of trailer protocol:
433 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
434 * along with IP replies if we wanted trailers sent to us,
435 * and also sent them in response to IP replies.
436 * This allowed either end to announce the desire to receive
437 * trailer packets.
438 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
439 * but formerly didn't normally send requests.
440 */
441static int log_arp_wrong_iface = 1;
442static int log_arp_movements = 1;
443static int log_arp_permanent_modify = 1;
444
445SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
446 &log_arp_wrong_iface, 0,
447 "log arp packets arriving on the wrong interface");
448SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
449 &log_arp_movements, 0,
450 "log arp replies from MACs different than the one in the cache");
451SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
452 &log_arp_permanent_modify, 0,
453 "log arp replies from MACs different than the one in the permanent arp entry");
454
455
456static void
457in_arpinput(struct mbuf *m)
458{
459 struct arphdr *ah;
460 struct ifnet *ifp = m->m_pkthdr.rcvif;
461 struct llentry *la = NULL;
462 struct rtentry *rt;
463 struct ifaddr *ifa;
464 struct in_ifaddr *ia;
465 struct sockaddr sa;
466 struct in_addr isaddr, itaddr, myaddr;
467 u_int8_t *enaddr = NULL;
468 int op, flags;
469 struct mbuf *m0;
470 int req_len;
471 int bridged = 0, is_bridge = 0;
472#ifdef DEV_CARP
473 int carp_match = 0;
474#endif
475 struct sockaddr_in sin;
476 sin.sin_len = sizeof(struct sockaddr_in);
477 sin.sin_family = AF_INET;
478 sin.sin_addr.s_addr = 0;
479
480 if (ifp->if_bridge)
481 bridged = 1;
482 if (ifp->if_type == IFT_BRIDGE)
483 is_bridge = 1;
484
485 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
486 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
487 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
488 return;
489 }
490
491 ah = mtod(m, struct arphdr *);
492 op = ntohs(ah->ar_op);
493 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
494 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
495
496 /*
497 * For a bridge, we want to check the address irrespective
498 * of the receive interface. (This will change slightly
499 * when we have clusters of interfaces).
500 * If the interface does not match, but the recieving interface
501 * is part of carp, we call carp_iamatch to see if this is a
502 * request for the virtual host ip.
503 * XXX: This is really ugly!
504 */
505 IN_IFADDR_RLOCK();
506 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
507 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
508 ia->ia_ifp == ifp) &&
509 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
510 ifa_ref(&ia->ia_ifa);
511 IN_IFADDR_RUNLOCK();
512 goto match;
513 }
514#ifdef DEV_CARP
515 if (ifp->if_carp != NULL &&
516 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) &&
517 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
518 carp_match = 1;
519 ifa_ref(&ia->ia_ifa);
520 IN_IFADDR_RUNLOCK();
521 goto match;
522 }
523#endif
524 }
525 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
526 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
527 ia->ia_ifp == ifp) &&
528 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
529 ifa_ref(&ia->ia_ifa);
530 IN_IFADDR_RUNLOCK();
531 goto match;
532 }
533
534#define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
535 (ia->ia_ifp->if_bridge == ifp->if_softc && \
536 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
537 addr == ia->ia_addr.sin_addr.s_addr)
538 /*
539 * Check the case when bridge shares its MAC address with
540 * some of its children, so packets are claimed by bridge
541 * itself (bridge_input() does it first), but they are really
542 * meant to be destined to the bridge member.
543 */
544 if (is_bridge) {
545 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
546 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
547 ifa_ref(&ia->ia_ifa);
548 ifp = ia->ia_ifp;
549 IN_IFADDR_RUNLOCK();
550 goto match;
551 }
552 }
553 }
554#undef BDG_MEMBER_MATCHES_ARP
555 IN_IFADDR_RUNLOCK();
556
557 /*
558 * No match, use the first inet address on the receive interface
559 * as a dummy address for the rest of the function.
560 */
561 IF_ADDR_LOCK(ifp);
562 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
563 if (ifa->ifa_addr->sa_family == AF_INET) {
564 ia = ifatoia(ifa);
565 ifa_ref(ifa);
566 IF_ADDR_UNLOCK(ifp);
567 goto match;
568 }
569 IF_ADDR_UNLOCK(ifp);
570
571 /*
572 * If bridging, fall back to using any inet address.
573 */
574 IN_IFADDR_RLOCK();
575 if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
576 IN_IFADDR_RUNLOCK();
577 goto drop;
578 }
579 ifa_ref(&ia->ia_ifa);
580 IN_IFADDR_RUNLOCK();
581match:
582 if (!enaddr)
583 enaddr = (u_int8_t *)IF_LLADDR(ifp);
584 myaddr = ia->ia_addr.sin_addr;
585 ifa_free(&ia->ia_ifa);
586 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
587 goto drop; /* it's from me, ignore it. */
588 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
589 log(LOG_ERR,
590 "arp: link address is broadcast for IP address %s!\n",
591 inet_ntoa(isaddr));
592 goto drop;
593 }
594 /*
595 * Warn if another host is using the same IP address, but only if the
596 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
597 * case we suppress the warning to avoid false positive complaints of
598 * potential misconfiguration.
599 */
600 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
601 log(LOG_ERR,
602 "arp: %*D is using my IP address %s on %s!\n",
603 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
604 inet_ntoa(isaddr), ifp->if_xname);
605 itaddr = myaddr;
606 goto reply;
607 }
608 if (ifp->if_flags & IFF_STATICARP)
609 goto reply;
610
611 bzero(&sin, sizeof(sin));
612 sin.sin_len = sizeof(struct sockaddr_in);
613 sin.sin_family = AF_INET;
614 sin.sin_addr = isaddr;
615 flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
616 flags |= LLE_EXCLUSIVE;
617 IF_AFDATA_LOCK(ifp);
618 la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
619 IF_AFDATA_UNLOCK(ifp);
620 if (la != NULL) {
621 /* the following is not an error when doing bridging */
622 if (!bridged && la->lle_tbl->llt_ifp != ifp
623#ifdef DEV_CARP
624 && (ifp->if_type != IFT_CARP || !carp_match)
625#endif
626 ) {
627 if (log_arp_wrong_iface)
628 log(LOG_ERR, "arp: %s is on %s "
629 "but got reply from %*D on %s\n",
630 inet_ntoa(isaddr),
631 la->lle_tbl->llt_ifp->if_xname,
632 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
633 ifp->if_xname);
634 goto reply;
635 }
636 if ((la->la_flags & LLE_VALID) &&
637 bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
638 if (la->la_flags & LLE_STATIC) {
639 log(LOG_ERR,
640 "arp: %*D attempts to modify permanent "
641 "entry for %s on %s\n",
642 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
643 inet_ntoa(isaddr), ifp->if_xname);
644 goto reply;
645 }
646 if (log_arp_movements) {
647 log(LOG_INFO, "arp: %s moved from %*D "
648 "to %*D on %s\n",
649 inet_ntoa(isaddr),
650 ifp->if_addrlen,
651 (u_char *)&la->ll_addr, ":",
652 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
653 ifp->if_xname);
654 }
655 }
656
657 if (ifp->if_addrlen != ah->ar_hln) {
658 log(LOG_WARNING,
659 "arp from %*D: addr len: new %d, i/f %d (ignored)",
660 ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
661 ah->ar_hln, ifp->if_addrlen);
662 goto reply;
663 }
664 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
665 la->la_flags |= LLE_VALID;
666
667 if (!(la->la_flags & LLE_STATIC)) {
668 la->la_expire = time_uptime + V_arpt_keep;
669 callout_reset(&la->la_timer, hz * V_arpt_keep,
670 arptimer, la);
671 }
672 la->la_asked = 0;
673 la->la_preempt = V_arp_maxtries;
674 if (la->la_hold != NULL) {
675 m0 = la->la_hold;
676 la->la_hold = 0;
677 memcpy(&sa, L3_ADDR(la), sizeof(sa));
678 LLE_WUNLOCK(la);
679
680 (*ifp->if_output)(ifp, m0, &sa, NULL);
681 return;
682 }
683 }
684reply:
685 if (op != ARPOP_REQUEST)
686 goto drop;
687
688 if (itaddr.s_addr == myaddr.s_addr) {
689 /* Shortcut.. the receiving interface is the target. */
690 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
691 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
692 } else {
693 struct llentry *lle = NULL;
694
695 if (!V_arp_proxyall)
696 goto drop;
697
698 sin.sin_addr = itaddr;
699 /* XXX MRT use table 0 for arp reply */
700 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
701 if (!rt)
702 goto drop;
703
704 /*
705 * Don't send proxies for nodes on the same interface
706 * as this one came out of, or we'll get into a fight
707 * over who claims what Ether address.
708 */
709 if (!rt->rt_ifp || rt->rt_ifp == ifp) {
710 RTFREE_LOCKED(rt);
711 goto drop;
712 }
713 IF_AFDATA_LOCK(rt->rt_ifp);
714 lle = lla_lookup(LLTABLE(rt->rt_ifp), 0, (struct sockaddr *)&sin);
715 IF_AFDATA_UNLOCK(rt->rt_ifp);
716 RTFREE_LOCKED(rt);
717
718 if (lle != NULL) {
719 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
720 (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
721 LLE_RUNLOCK(lle);
722 } else
723 goto drop;
724
725 /*
726 * Also check that the node which sent the ARP packet
727 * is on the the interface we expect it to be on. This
728 * avoids ARP chaos if an interface is connected to the
729 * wrong network.
730 */
731 sin.sin_addr = isaddr;
732
733 /* XXX MRT use table 0 for arp checks */
734 rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
735 if (!rt)
736 goto drop;
737 if (rt->rt_ifp != ifp) {
738 log(LOG_INFO, "arp_proxy: ignoring request"
739 " from %s via %s, expecting %s\n",
740 inet_ntoa(isaddr), ifp->if_xname,
741 rt->rt_ifp->if_xname);
742 RTFREE_LOCKED(rt);
743 goto drop;
744 }
745 RTFREE_LOCKED(rt);
746
747#ifdef DEBUG_PROXY
748 printf("arp: proxying for %s\n",
749 inet_ntoa(itaddr));
750#endif
751 }
752
753 if (la != NULL)
754 LLE_WUNLOCK(la);
755 if (itaddr.s_addr == myaddr.s_addr &&
756 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
757 /* RFC 3927 link-local IPv4; always reply by broadcast. */
758#ifdef DEBUG_LINKLOCAL
759 printf("arp: sending reply for link-local addr %s\n",
760 inet_ntoa(itaddr));
761#endif
762 m->m_flags |= M_BCAST;
763 m->m_flags &= ~M_MCAST;
764 } else {
765 /* default behaviour; never reply by broadcast. */
766 m->m_flags &= ~(M_BCAST|M_MCAST);
767 }
768 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
769 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
770 ah->ar_op = htons(ARPOP_REPLY);
771 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
772 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
773 m->m_pkthdr.len = m->m_len;
774 sa.sa_family = AF_ARP;
775 sa.sa_len = 2;
776 (*ifp->if_output)(ifp, m, &sa, NULL);
777 return;
778
779drop:
780 if (la != NULL)
781 LLE_WUNLOCK(la);
782 m_freem(m);
783}
784#endif
785
786void
787arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
788{
789 struct llentry *lle;
790
791 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
792 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
793 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
794 /*
795 * interface address is considered static entry
796 * because the output of the arp utility shows
797 * that L2 entry as permanent
798 */
799 IF_AFDATA_LOCK(ifp);
800 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
801 (struct sockaddr *)IA_SIN(ifa));
802 IF_AFDATA_UNLOCK(ifp);
803 if (lle == NULL)
804 log(LOG_INFO, "arp_ifinit: cannot create arp "
805 "entry for interface address\n");
806 else
807 LLE_RUNLOCK(lle);
808 }
809 ifa->ifa_rtrequest = NULL;
810}
811
812void
813arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
814{
815 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
816 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
817 &IA_SIN(ifa)->sin_addr, enaddr);
818 ifa->ifa_rtrequest = NULL;
819}
820
821static void
822arp_init(void)
823{
824
825 netisr_register(&arp_nh);
826}
827SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);