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 #include "opt_mac.h"
43 #include "opt_carp.h"
44
45 #include <sys/param.h>
46 #include <sys/kernel.h>
47 #include <sys/queue.h>
48 #include <sys/sysctl.h>
49 #include <sys/systm.h>
50 #include <sys/mbuf.h>
51 #include <sys/malloc.h>
52 #include <sys/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/route.h>
59 #include <net/netisr.h>
60 #include <net/if_llc.h>
61 #include <net/ethernet.h>
62
63 #include <netinet/in.h>
64 #include <netinet/in_var.h>
65 #include <netinet/if_ether.h>
66
67 #include <net/if_arc.h>
68 #include <net/iso88025.h>
69
70 #ifdef DEV_CARP
71 #include <netinet/ip_carp.h>
72 #endif
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
82 /* timer values */
83 static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
84
85 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
86 &arpt_keep, 0, "ARP entry lifetime in seconds");
87
88 #define rt_expire rt_rmx.rmx_expire
89
90 struct llinfo_arp {
91 struct callout la_timer;
92 struct rtentry *la_rt;
93 struct mbuf *la_hold; /* last packet until resolved/timeout */
94 u_short la_preempt; /* countdown for pre-expiry arps */
95 u_short la_asked; /* # requests sent */
96 };
97
98 static struct ifqueue arpintrq;
99 static int arp_allocated;
100
101 static int arp_maxtries = 5;
102 static int useloopback = 1; /* use loopback interface for local traffic */
103 static int arp_proxyall = 0;
104
105 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
106 &arp_maxtries, 0, "ARP resolution attempts before returning error");
107 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
108 &useloopback, 0, "Use the loopback interface for local traffic");
109 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
110 &arp_proxyall, 0, "Enable proxy ARP for all suitable requests");
111
112 static void arp_init(void);
113 static void arp_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
114 static void arprequest(struct ifnet *,
115 struct in_addr *, struct in_addr *, u_char *);
116 static void arpintr(struct mbuf *);
117 static void arptimer(void *);
118 static struct rtentry
119 *arplookup(u_long, int, int);
120 #ifdef INET
121 static void in_arpinput(struct mbuf *);
122 #endif
123
124 /*
125 * Timeout routine.
126 */
127 static void
128 arptimer(void *arg)
129 {
130 struct rtentry *rt = (struct rtentry *)arg;
131
132 RT_LOCK_ASSERT(rt);
133 /*
134 * The lock is needed to close a theoretical race
135 * between spontaneous expiry and intentional removal.
136 * We still got an extra reference on rtentry, so can
137 * safely pass pointers to its contents.
138 */
139 RT_UNLOCK(rt);
140
141 rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL);
142 }
143
144 /*
145 * Parallel to llc_rtrequest.
146 */
147 static void
148 arp_rtrequest(int req, struct rtentry *rt, struct rt_addrinfo *info)
149 {
150 struct sockaddr *gate;
151 struct llinfo_arp *la;
152 static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
153 struct in_ifaddr *ia;
154 struct ifaddr *ifa;
155
156 RT_LOCK_ASSERT(rt);
157
158 if (rt->rt_flags & RTF_GATEWAY)
159 return;
160 gate = rt->rt_gateway;
161 la = (struct llinfo_arp *)rt->rt_llinfo;
162 switch (req) {
163
164 case RTM_ADD:
165 /*
166 * XXX: If this is a manually added route to interface
167 * such as older version of routed or gated might provide,
168 * restore cloning bit.
169 */
170 if ((rt->rt_flags & RTF_HOST) == 0 &&
171 rt_mask(rt) != NULL &&
172 SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
173 rt->rt_flags |= RTF_CLONING;
174 if (rt->rt_flags & RTF_CLONING) {
175 /*
176 * Case 1: This route should come from a route to iface.
177 */
178 rt_setgate(rt, rt_key(rt),
179 (struct sockaddr *)&null_sdl);
180 gate = rt->rt_gateway;
181 SDL(gate)->sdl_type = rt->rt_ifp->if_type;
182 SDL(gate)->sdl_index = rt->rt_ifp->if_index;
183 rt->rt_expire = time_uptime;
184 break;
185 }
186 /* Announce a new entry if requested. */
187 if (rt->rt_flags & RTF_ANNOUNCE)
188 arprequest(rt->rt_ifp,
189 &SIN(rt_key(rt))->sin_addr,
190 &SIN(rt_key(rt))->sin_addr,
191 (u_char *)LLADDR(SDL(gate)));
192 /*FALLTHROUGH*/
193 case RTM_RESOLVE:
194 if (gate->sa_family != AF_LINK ||
195 gate->sa_len < sizeof(null_sdl)) {
196 log(LOG_DEBUG, "%s: bad gateway %s%s\n", __func__,
197 inet_ntoa(SIN(rt_key(rt))->sin_addr),
198 (gate->sa_family != AF_LINK) ?
199 " (!AF_LINK)": "");
200 break;
201 }
202 SDL(gate)->sdl_type = rt->rt_ifp->if_type;
203 SDL(gate)->sdl_index = rt->rt_ifp->if_index;
204 if (la != 0)
205 break; /* This happens on a route change */
206 /*
207 * Case 2: This route may come from cloning, or a manual route
208 * add with a LL address.
209 */
210 R_Zalloc(la, struct llinfo_arp *, sizeof(*la));
211 rt->rt_llinfo = (caddr_t)la;
212 if (la == 0) {
213 log(LOG_DEBUG, "%s: malloc failed\n", __func__);
214 break;
215 }
216 arp_allocated++;
217 /*
218 * We are storing a route entry outside of radix tree. So,
219 * it can be found and accessed by other means than radix
220 * lookup. The routing code assumes that any rtentry detached
221 * from radix can be destroyed safely. To prevent this, we
222 * add an additional reference.
223 */
224 RT_ADDREF(rt);
225 la->la_rt = rt;
226 rt->rt_flags |= RTF_LLINFO;
227 callout_init_mtx(&la->la_timer, &rt->rt_mtx,
228 CALLOUT_RETURNUNLOCKED);
229
230 #ifdef INET
231 /*
232 * This keeps the multicast addresses from showing up
233 * in `arp -a' listings as unresolved. It's not actually
234 * functional. Then the same for broadcast.
235 */
236 if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr)) &&
237 rt->rt_ifp->if_type != IFT_ARCNET) {
238 ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr,
239 LLADDR(SDL(gate)));
240 SDL(gate)->sdl_alen = 6;
241 rt->rt_expire = 0;
242 }
243 if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
244 memcpy(LLADDR(SDL(gate)), rt->rt_ifp->if_broadcastaddr,
245 rt->rt_ifp->if_addrlen);
246 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen;
247 rt->rt_expire = 0;
248 }
249 #endif
250
251 TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) {
252 if (ia->ia_ifp == rt->rt_ifp &&
253 SIN(rt_key(rt))->sin_addr.s_addr ==
254 (IA_SIN(ia))->sin_addr.s_addr)
255 break;
256 }
257 if (ia) {
258 /*
259 * This test used to be
260 * if (loif.if_flags & IFF_UP)
261 * It allowed local traffic to be forced
262 * through the hardware by configuring the loopback down.
263 * However, it causes problems during network configuration
264 * for boards that can't receive packets they send.
265 * It is now necessary to clear "useloopback" and remove
266 * the route to force traffic out to the hardware.
267 */
268 rt->rt_expire = 0;
269 bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)),
270 SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen);
271 if (useloopback) {
272 rt->rt_ifp = loif;
273 rt->rt_rmx.rmx_mtu = loif->if_mtu;
274 }
275
276 /*
277 * make sure to set rt->rt_ifa to the interface
278 * address we are using, otherwise we will have trouble
279 * with source address selection.
280 */
281 ifa = &ia->ia_ifa;
282 if (ifa != rt->rt_ifa) {
283 IFAFREE(rt->rt_ifa);
284 IFAREF(ifa);
285 rt->rt_ifa = ifa;
286 }
287 }
288 break;
289
290 case RTM_DELETE:
291 if (la == NULL) /* XXX: at least CARP does this. */
292 break;
293 callout_stop(&la->la_timer);
294 rt->rt_llinfo = NULL;
295 rt->rt_flags &= ~RTF_LLINFO;
296 RT_REMREF(rt);
297 if (la->la_hold)
298 m_freem(la->la_hold);
299 Free((caddr_t)la);
300 }
301 }
302
303 /*
304 * Broadcast an ARP request. Caller specifies:
305 * - arp header source ip address
306 * - arp header target ip address
307 * - arp header source ethernet address
308 */
309 static void
310 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,
311 u_char *enaddr)
312 {
313 struct mbuf *m;
314 struct arphdr *ah;
315 struct sockaddr sa;
316
317 if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
318 return;
319 m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
320 2*ifp->if_data.ifi_addrlen;
321 m->m_pkthdr.len = m->m_len;
322 MH_ALIGN(m, m->m_len);
323 ah = mtod(m, struct arphdr *);
324 bzero((caddr_t)ah, m->m_len);
325 #ifdef MAC
326 mac_create_mbuf_linklayer(ifp, m);
327 #endif
328 ah->ar_pro = htons(ETHERTYPE_IP);
329 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
330 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
331 ah->ar_op = htons(ARPOP_REQUEST);
332 bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
333 bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
334 bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
335 sa.sa_family = AF_ARP;
336 sa.sa_len = 2;
337 m->m_flags |= M_BCAST;
338 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
339
340 return;
341 }
342
343 /*
344 * Resolve an IP address into an ethernet address.
345 * On input:
346 * ifp is the interface we use
347 * dst is the next hop,
348 * rt0 is the route to the final destination (possibly useless)
349 * m is the mbuf
350 * desten is where we want the address.
351 *
352 * On success, desten is filled in and the function returns 0;
353 * If the packet must be held pending resolution, we return EWOULDBLOCK
354 * On other errors, we return the corresponding error code.
355 */
356 int
357 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
358 struct sockaddr *dst, u_char *desten)
359 {
360 struct llinfo_arp *la = NULL;
361 struct rtentry *rt = NULL;
362 struct sockaddr_dl *sdl;
363 int error;
364
365 if (m->m_flags & M_BCAST) { /* broadcast */
366 (void)memcpy(desten, ifp->if_broadcastaddr, ifp->if_addrlen);
367 return (0);
368 }
369 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {/* multicast */
370 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
371 return (0);
372 }
373
374 if (rt0 != NULL) {
375 error = rt_check(&rt, &rt0, dst);
376 if (error) {
377 m_freem(m);
378 return error;
379 }
380 la = (struct llinfo_arp *)rt->rt_llinfo;
381 if (la == NULL)
382 RT_UNLOCK(rt);
383 }
384 if (la == NULL) {
385 /*
386 * We enter this block in case if rt0 was NULL,
387 * or if rt found by rt_check() didn't have llinfo.
388 */
389 rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0);
390 if (rt == NULL) {
391 log(LOG_DEBUG,
392 "arpresolve: can't allocate route for %s\n",
393 inet_ntoa(SIN(dst)->sin_addr));
394 m_freem(m);
395 return (EINVAL); /* XXX */
396 }
397 la = (struct llinfo_arp *)rt->rt_llinfo;
398 if (la == NULL) {
399 RT_UNLOCK(rt);
400 log(LOG_DEBUG,
401 "arpresolve: can't allocate llinfo for %s\n",
402 inet_ntoa(SIN(dst)->sin_addr));
403 m_freem(m);
404 return (EINVAL); /* XXX */
405 }
406 }
407 sdl = SDL(rt->rt_gateway);
408 /*
409 * Check the address family and length is valid, the address
410 * is resolved; otherwise, try to resolve.
411 */
412 if ((rt->rt_expire == 0 || rt->rt_expire > time_uptime) &&
413 sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) {
414
415 bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
416
417 /*
418 * If entry has an expiry time and it is approaching,
419 * send an ARP request.
420 */
421 if ((rt->rt_expire != 0) &&
422 (time_uptime + la->la_preempt > rt->rt_expire)) {
423 struct in_addr sin =
424 SIN(rt->rt_ifa->ifa_addr)->sin_addr;
425
426 la->la_preempt--;
427 RT_UNLOCK(rt);
428 arprequest(ifp, &sin, &SIN(dst)->sin_addr,
429 IF_LLADDR(ifp));
430 return (0);
431 }
432
433 RT_UNLOCK(rt);
434 return (0);
435 }
436 /*
437 * If ARP is disabled or static on this interface, stop.
438 * XXX
439 * Probably should not allocate empty llinfo struct if we are
440 * not going to be sending out an arp request.
441 */
442 if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) {
443 RT_UNLOCK(rt);
444 m_freem(m);
445 return (EINVAL);
446 }
447 /*
448 * There is an arptab entry, but no ethernet address
449 * response yet. Replace the held mbuf with this
450 * latest one.
451 */
452 if (la->la_hold)
453 m_freem(la->la_hold);
454 la->la_hold = m;
455
456 KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry"));
457
458 /*
459 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
460 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
461 * if we have already sent arp_maxtries ARP requests. Retransmit the
462 * ARP request, but not faster than one request per second.
463 */
464 if (la->la_asked < arp_maxtries)
465 error = EWOULDBLOCK; /* First request. */
466 else
467 error = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH;
468
469 if (la->la_asked == 0 || rt->rt_expire != time_uptime) {
470 struct in_addr sin =
471 SIN(rt->rt_ifa->ifa_addr)->sin_addr;
472
473 rt->rt_expire = time_uptime;
474 callout_reset(&la->la_timer, hz, arptimer, rt);
475 la->la_asked++;
476 RT_UNLOCK(rt);
477
478 arprequest(ifp, &sin, &SIN(dst)->sin_addr,
479 IF_LLADDR(ifp));
480 } else
481 RT_UNLOCK(rt);
482
483 return (error);
484 }
485
486 /*
487 * Common length and type checks are done here,
488 * then the protocol-specific routine is called.
489 */
490 static void
491 arpintr(struct mbuf *m)
492 {
493 struct arphdr *ar;
494
495 if (m->m_len < sizeof(struct arphdr) &&
496 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
497 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
498 return;
499 }
500 ar = mtod(m, struct arphdr *);
501
502 if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
503 ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
504 ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
505 ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
506 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
507 (unsigned char *)&ar->ar_hrd, "");
508 m_freem(m);
509 return;
510 }
511
512 if (m->m_len < arphdr_len(ar)) {
513 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
514 log(LOG_ERR, "arp: runt packet\n");
515 m_freem(m);
516 return;
517 }
518 ar = mtod(m, struct arphdr *);
519 }
520
521 switch (ntohs(ar->ar_pro)) {
522 #ifdef INET
523 case ETHERTYPE_IP:
524 in_arpinput(m);
525 return;
526 #endif
527 }
528 m_freem(m);
529 }
530
531 #ifdef INET
532 /*
533 * ARP for Internet protocols on 10 Mb/s Ethernet.
534 * Algorithm is that given in RFC 826.
535 * In addition, a sanity check is performed on the sender
536 * protocol address, to catch impersonators.
537 * We no longer handle negotiations for use of trailer protocol:
538 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
539 * along with IP replies if we wanted trailers sent to us,
540 * and also sent them in response to IP replies.
541 * This allowed either end to announce the desire to receive
542 * trailer packets.
543 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
544 * but formerly didn't normally send requests.
545 */
546 static int log_arp_wrong_iface = 1;
547 static int log_arp_movements = 1;
548 static int log_arp_permanent_modify = 1;
549
550 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
551 &log_arp_wrong_iface, 0,
552 "log arp packets arriving on the wrong interface");
553 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
554 &log_arp_movements, 0,
555 "log arp replies from MACs different than the one in the cache");
556 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
557 &log_arp_permanent_modify, 0,
558 "log arp replies from MACs different than the one in the permanent arp entry");
559
560
561 static void
562 in_arpinput(struct mbuf *m)
563 {
564 struct arphdr *ah;
565 struct ifnet *ifp = m->m_pkthdr.rcvif;
566 struct llinfo_arp *la;
567 struct rtentry *rt;
568 struct ifaddr *ifa;
569 struct in_ifaddr *ia;
570 struct sockaddr_dl *sdl;
571 struct sockaddr sa;
572 struct in_addr isaddr, itaddr, myaddr;
573 struct mbuf *hold;
574 u_int8_t *enaddr = NULL;
575 int op, rif_len;
576 int req_len;
577 int bridged = 0;
578 #ifdef DEV_CARP
579 int carp_match = 0;
580 #endif
581
582 if (ifp->if_bridge)
583 bridged = 1;
584
585 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
586 if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
587 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
588 return;
589 }
590
591 ah = mtod(m, struct arphdr *);
592 op = ntohs(ah->ar_op);
593 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
594 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
595
596 /*
597 * For a bridge, we want to check the address irrespective
598 * of the receive interface. (This will change slightly
599 * when we have clusters of interfaces).
600 * If the interface does not match, but the recieving interface
601 * is part of carp, we call carp_iamatch to see if this is a
602 * request for the virtual host ip.
603 * XXX: This is really ugly!
604 */
605 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
606 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
607 (ia->ia_ifp == ifp)) &&
608 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
609 goto match;
610 #ifdef DEV_CARP
611 if (ifp->if_carp != NULL &&
612 carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) &&
613 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
614 carp_match = 1;
615 goto match;
616 }
617 #endif
618 }
619 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
620 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
621 (ia->ia_ifp == ifp)) &&
622 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
623 goto match;
624 /*
625 * No match, use the first inet address on the receive interface
626 * as a dummy address for the rest of the function.
627 */
628 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
629 if (ifa->ifa_addr->sa_family == AF_INET) {
630 ia = ifatoia(ifa);
631 goto match;
632 }
633 /*
634 * If bridging, fall back to using any inet address.
635 */
636 if (!bridged || (ia = TAILQ_FIRST(&in_ifaddrhead)) == NULL)
637 goto drop;
638 match:
639 if (!enaddr)
640 enaddr = (u_int8_t *)IF_LLADDR(ifp);
641 myaddr = ia->ia_addr.sin_addr;
642 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
643 goto drop; /* it's from me, ignore it. */
644 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
645 log(LOG_ERR,
646 "arp: link address is broadcast for IP address %s!\n",
647 inet_ntoa(isaddr));
648 goto drop;
649 }
650 /*
651 * Warn if another host is using the same IP address, but only if the
652 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
653 * case we suppress the warning to avoid false positive complaints of
654 * potential misconfiguration.
655 */
656 if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
657 log(LOG_ERR,
658 "arp: %*D is using my IP address %s!\n",
659 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
660 inet_ntoa(isaddr));
661 itaddr = myaddr;
662 goto reply;
663 }
664 if (ifp->if_flags & IFF_STATICARP)
665 goto reply;
666 rt = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0);
667 if (rt != NULL) {
668 la = (struct llinfo_arp *)rt->rt_llinfo;
669 if (la == NULL) {
670 RT_UNLOCK(rt);
671 goto reply;
672 }
673 } else
674 goto reply;
675
676 /* The following is not an error when doing bridging. */
677 if (!bridged && rt->rt_ifp != ifp
678 #ifdef DEV_CARP
679 && (ifp->if_type != IFT_CARP || !carp_match)
680 #endif
681 ) {
682 if (log_arp_wrong_iface)
683 log(LOG_ERR, "arp: %s is on %s but got reply from %*D on %s\n",
684 inet_ntoa(isaddr),
685 rt->rt_ifp->if_xname,
686 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
687 ifp->if_xname);
688 RT_UNLOCK(rt);
689 goto reply;
690 }
691 sdl = SDL(rt->rt_gateway);
692 if (sdl->sdl_alen &&
693 bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) {
694 if (rt->rt_expire) {
695 if (log_arp_movements)
696 log(LOG_INFO, "arp: %s moved from %*D to %*D on %s\n",
697 inet_ntoa(isaddr),
698 ifp->if_addrlen, (u_char *)LLADDR(sdl), ":",
699 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
700 ifp->if_xname);
701 } else {
702 RT_UNLOCK(rt);
703 if (log_arp_permanent_modify)
704 log(LOG_ERR, "arp: %*D attempts to modify "
705 "permanent entry for %s on %s\n",
706 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
707 inet_ntoa(isaddr), ifp->if_xname);
708 goto reply;
709 }
710 }
711 /*
712 * sanity check for the address length.
713 * XXX this does not work for protocols with variable address
714 * length. -is
715 */
716 if (sdl->sdl_alen &&
717 sdl->sdl_alen != ah->ar_hln) {
718 log(LOG_WARNING,
719 "arp from %*D: new addr len %d, was %d",
720 ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
721 ah->ar_hln, sdl->sdl_alen);
722 }
723 if (ifp->if_addrlen != ah->ar_hln) {
724 log(LOG_WARNING,
725 "arp from %*D: addr len: new %d, i/f %d (ignored)",
726 ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
727 ah->ar_hln, ifp->if_addrlen);
728 RT_UNLOCK(rt);
729 goto reply;
730 }
731 (void)memcpy(LLADDR(sdl), ar_sha(ah),
732 sdl->sdl_alen = ah->ar_hln);
733 /*
734 * If we receive an arp from a token-ring station over
735 * a token-ring nic then try to save the source
736 * routing info.
737 */
738 if (ifp->if_type == IFT_ISO88025) {
739 struct iso88025_header *th = NULL;
740 struct iso88025_sockaddr_dl_data *trld;
741
742 th = (struct iso88025_header *)m->m_pkthdr.header;
743 trld = SDL_ISO88025(sdl);
744 rif_len = TR_RCF_RIFLEN(th->rcf);
745 if ((th->iso88025_shost[0] & TR_RII) &&
746 (rif_len > 2)) {
747 trld->trld_rcf = th->rcf;
748 trld->trld_rcf ^= htons(TR_RCF_DIR);
749 memcpy(trld->trld_route, th->rd, rif_len - 2);
750 trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK);
751 /*
752 * Set up source routing information for
753 * reply packet (XXX)
754 */
755 m->m_data -= rif_len;
756 m->m_len += rif_len;
757 m->m_pkthdr.len += rif_len;
758 } else {
759 th->iso88025_shost[0] &= ~TR_RII;
760 trld->trld_rcf = 0;
761 }
762 m->m_data -= 8;
763 m->m_len += 8;
764 m->m_pkthdr.len += 8;
765 th->rcf = trld->trld_rcf;
766 }
767 if (rt->rt_expire) {
768 rt->rt_expire = time_uptime + arpt_keep;
769 callout_reset(&la->la_timer, hz * arpt_keep, arptimer, rt);
770 }
771 la->la_asked = 0;
772 la->la_preempt = arp_maxtries;
773 hold = la->la_hold;
774 la->la_hold = NULL;
775 RT_UNLOCK(rt);
776 if (hold != NULL)
777 (*ifp->if_output)(ifp, hold, rt_key(rt), rt);
778
779 reply:
780 if (op != ARPOP_REQUEST)
781 goto drop;
782 if (itaddr.s_addr == myaddr.s_addr) {
783 /* I am the target */
784 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
785 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
786 } else {
787 rt = arplookup(itaddr.s_addr, 0, SIN_PROXY);
788 if (rt == NULL) {
789 struct sockaddr_in sin;
790
791 if (!arp_proxyall)
792 goto drop;
793
794 bzero(&sin, sizeof sin);
795 sin.sin_family = AF_INET;
796 sin.sin_len = sizeof sin;
797 sin.sin_addr = itaddr;
798
799 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
800 if (!rt)
801 goto drop;
802 /*
803 * Don't send proxies for nodes on the same interface
804 * as this one came out of, or we'll get into a fight
805 * over who claims what Ether address.
806 */
807 if (rt->rt_ifp == ifp) {
808 rtfree(rt);
809 goto drop;
810 }
811 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
812 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
813 rtfree(rt);
814
815 /*
816 * Also check that the node which sent the ARP packet
817 * is on the the interface we expect it to be on. This
818 * avoids ARP chaos if an interface is connected to the
819 * wrong network.
820 */
821 sin.sin_addr = isaddr;
822
823 rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
824 if (!rt)
825 goto drop;
826 if (rt->rt_ifp != ifp) {
827 log(LOG_INFO, "arp_proxy: ignoring request"
828 " from %s via %s, expecting %s\n",
829 inet_ntoa(isaddr), ifp->if_xname,
830 rt->rt_ifp->if_xname);
831 rtfree(rt);
832 goto drop;
833 }
834 rtfree(rt);
835
836 #ifdef DEBUG_PROXY
837 printf("arp: proxying for %s\n",
838 inet_ntoa(itaddr));
839 #endif
840 } else {
841 /*
842 * Return proxied ARP replies only on the interface
843 * or bridge cluster where this network resides.
844 * Otherwise we may conflict with the host we are
845 * proxying for.
846 */
847 if (rt->rt_ifp != ifp &&
848 (rt->rt_ifp->if_bridge != ifp->if_bridge ||
849 ifp->if_bridge == NULL)) {
850 RT_UNLOCK(rt);
851 goto drop;
852 }
853 sdl = SDL(rt->rt_gateway);
854 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
855 (void)memcpy(ar_sha(ah), LLADDR(sdl), ah->ar_hln);
856 RT_UNLOCK(rt);
857 }
858 }
859
860 if (itaddr.s_addr == myaddr.s_addr &&
861 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
862 /* RFC 3927 link-local IPv4; always reply by broadcast. */
863 #ifdef DEBUG_LINKLOCAL
864 printf("arp: sending reply for link-local addr %s\n",
865 inet_ntoa(itaddr));
866 #endif
867 m->m_flags |= M_BCAST;
868 m->m_flags &= ~M_MCAST;
869 } else {
870 /* default behaviour; never reply by broadcast. */
871 m->m_flags &= ~(M_BCAST|M_MCAST);
872 }
873 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
874 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
875 ah->ar_op = htons(ARPOP_REPLY);
876 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
877 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
878 m->m_pkthdr.len = m->m_len;
879 sa.sa_family = AF_ARP;
880 sa.sa_len = 2;
881 (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
882 return;
883
884 drop:
885 m_freem(m);
886 }
887 #endif
888
889 /*
890 * Lookup or enter a new address in arptab.
891 */
892 static struct rtentry *
893 arplookup(u_long addr, int create, int proxy)
894 {
895 struct rtentry *rt;
896 struct sockaddr_inarp sin;
897 const char *why = 0;
898
899 bzero(&sin, sizeof(sin));
900 sin.sin_len = sizeof(sin);
901 sin.sin_family = AF_INET;
902 sin.sin_addr.s_addr = addr;
903 if (proxy)
904 sin.sin_other = SIN_PROXY;
905 rt = rtalloc1((struct sockaddr *)&sin, create, 0UL);
906 if (rt == 0)
907 return (0);
908
909 if (rt->rt_flags & RTF_GATEWAY)
910 why = "host is not on local network";
911 else if ((rt->rt_flags & RTF_LLINFO) == 0)
912 why = "could not allocate llinfo";
913 else if (rt->rt_gateway->sa_family != AF_LINK)
914 why = "gateway route is not ours";
915
916 if (why) {
917 #define ISDYNCLONE(_rt) \
918 (((_rt)->rt_flags & (RTF_STATIC | RTF_WASCLONED)) == RTF_WASCLONED)
919 if (create)
920 log(LOG_DEBUG, "arplookup %s failed: %s\n",
921 inet_ntoa(sin.sin_addr), why);
922 /*
923 * If there are no references to this Layer 2 route,
924 * and it is a cloned route, and not static, and
925 * arplookup() is creating the route, then purge
926 * it from the routing table as it is probably bogus.
927 */
928 if (rt->rt_refcnt == 1 && ISDYNCLONE(rt))
929 rtexpunge(rt);
930 RTFREE_LOCKED(rt);
931 return (0);
932 #undef ISDYNCLONE
933 } else {
934 RT_REMREF(rt);
935 return (rt);
936 }
937 }
938
939 void
940 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
941 {
942 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
943 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
944 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
945 ifa->ifa_rtrequest = arp_rtrequest;
946 ifa->ifa_flags |= RTF_CLONING;
947 }
948
949 void
950 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
951 {
952 if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
953 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
954 &IA_SIN(ifa)->sin_addr, enaddr);
955 ifa->ifa_rtrequest = arp_rtrequest;
956 ifa->ifa_flags |= RTF_CLONING;
957 }
958
959 static void
960 arp_init(void)
961 {
962
963 arpintrq.ifq_maxlen = 50;
964 mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF);
965 netisr_register(NETISR_ARP, arpintr, &arpintrq, NETISR_MPSAFE);
966 }
967 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);
Cache object: ac43c054e9c5322d8cd45a6f62d44eec
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