2 * SPDX-License-Identifier: BSD-3-Clause
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31 * @(#)if_ether.c 8.1 (Berkeley) 6/10/93
35 * Ethernet address resolution protocol.
37 * add "inuse/lock" bit (or ref. count) along with valid bit
40 #include <sys/cdefs.h>
43 #include <sys/param.h>
44 #include <sys/eventhandler.h>
45 #include <sys/kernel.h>
47 #include <sys/queue.h>
48 #include <sys/sysctl.h>
49 #include <sys/systm.h>
51 #include <sys/malloc.h>
53 #include <sys/socket.h>
54 #include <sys/syslog.h>
57 #include <net/if_var.h>
58 #include <net/if_dl.h>
59 #include <net/if_private.h>
60 #include <net/if_types.h>
61 #include <net/netisr.h>
62 #include <net/ethernet.h>
63 #include <net/route.h>
64 #include <net/route/nhop.h>
67 #include <netinet/in.h>
68 #include <netinet/in_fib.h>
69 #include <netinet/in_var.h>
70 #include <net/if_llatbl.h>
71 #include <netinet/if_ether.h>
73 #include <netinet/ip_carp.h>
76 #include <security/mac/mac_framework.h>
78 #define SIN(s) ((const struct sockaddr_in *)(s))
80 static struct timeval arp_lastlog;
81 static int arp_curpps;
82 static int arp_maxpps = 1;
84 /* Simple ARP state machine */
85 enum arp_llinfo_state {
86 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */
87 ARP_LLINFO_REACHABLE, /* LLE is valid */
88 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */
89 ARP_LLINFO_DELETED, /* LLE is deleted */
92 SYSCTL_DECL(_net_link_ether);
93 static SYSCTL_NODE(_net_link_ether, PF_INET, inet,
94 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
96 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp,
97 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
101 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20
103 VNET_DEFINE_STATIC(int, arp_maxtries) = 5;
104 VNET_DEFINE_STATIC(int, arp_proxyall) = 0;
105 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for
107 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/
108 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */
109 VNET_PCPUSTAT_SYSINIT(arpstat);
112 VNET_PCPUSTAT_SYSUNINIT(arpstat);
115 VNET_DEFINE_STATIC(int, arp_maxhold) = 16;
117 #define V_arpt_keep VNET(arpt_keep)
118 #define V_arpt_down VNET(arpt_down)
119 #define V_arpt_rexmit VNET(arpt_rexmit)
120 #define V_arp_maxtries VNET(arp_maxtries)
121 #define V_arp_proxyall VNET(arp_proxyall)
122 #define V_arp_maxhold VNET(arp_maxhold)
124 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW,
125 &VNET_NAME(arpt_keep), 0,
126 "ARP entry lifetime in seconds");
127 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW,
128 &VNET_NAME(arp_maxtries), 0,
129 "ARP resolution attempts before returning error");
130 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW,
131 &VNET_NAME(arp_proxyall), 0,
132 "Enable proxy ARP for all suitable requests");
133 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW,
134 &VNET_NAME(arpt_down), 0,
135 "Incomplete ARP entry lifetime in seconds");
136 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat,
137 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)");
138 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW,
139 &VNET_NAME(arp_maxhold), 0,
140 "Number of packets to hold per ARP entry");
141 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second,
142 CTLFLAG_RW, &arp_maxpps, 0,
143 "Maximum number of remotely triggered ARP messages that can be "
144 "logged per second");
147 * Due to the exponential backoff algorithm used for the interval between GARP
148 * retransmissions, the maximum number of retransmissions is limited for
149 * sanity. This limit corresponds to a maximum interval between retransmissions
150 * of 2^16 seconds ~= 18 hours.
152 * Making this limit more dynamic is more complicated than worthwhile,
153 * especially since sending out GARPs spaced days apart would be of little
154 * use. A maximum dynamic limit would look something like:
156 * const int max = fls(INT_MAX / hz) - 1;
158 #define MAX_GARP_RETRANSMITS 16
159 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS);
160 static int garp_rexmit_count = 0; /* GARP retransmission setting. */
162 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count,
163 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE,
164 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I",
165 "Number of times to retransmit GARP packets;"
166 " 0 to disable, maximum of 16");
168 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */
169 #define V_arp_log_level VNET(arp_log_level)
170 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW,
171 &VNET_NAME(arp_log_level), 0,
172 "Minimum log(9) level for recording rate limited arp log messages. "
173 "The higher will be log more (emerg=0, info=6 (default), debug=7).");
174 #define ARP_LOG(pri, ...) do { \
175 if ((pri) <= V_arp_log_level && \
176 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \
177 log((pri), "arp: " __VA_ARGS__); \
180 static void arpintr(struct mbuf *);
181 static void arptimer(void *);
183 static void in_arpinput(struct mbuf *);
186 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr,
187 struct ifnet *ifp, int bridged, struct llentry *la);
188 static void arp_mark_lle_reachable(struct llentry *la, struct ifnet *ifp);
189 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp);
191 static eventhandler_tag iflladdr_tag;
193 static const struct netisr_handler arp_nh = {
195 .nh_handler = arpintr,
196 .nh_proto = NETISR_ARP,
197 .nh_policy = NETISR_POLICY_SOURCE,
201 * Timeout routine. Age arp_tab entries periodically.
206 struct llentry *lle = (struct llentry *)arg;
209 if (lle->la_flags & LLE_STATIC) {
213 if (callout_pending(&lle->lle_timer)) {
215 * Here we are a bit odd here in the treatment of
216 * active/pending. If the pending bit is set, it got
217 * rescheduled before I ran. The active
218 * bit we ignore, since if it was stopped
219 * in ll_tablefree() and was currently running
220 * it would have return 0 so the code would
221 * not have deleted it since the callout could
222 * not be stopped so we want to go through
223 * with the delete here now. If the callout
224 * was restarted, the pending bit will be back on and
225 * we just want to bail since the callout_reset would
226 * return 1 and our reference would have been removed
227 * by arpresolve() below.
232 ifp = lle->lle_tbl->llt_ifp;
233 CURVNET_SET(ifp->if_vnet);
235 switch (lle->ln_state) {
236 case ARP_LLINFO_REACHABLE:
239 * Expiration time is approaching.
240 * Request usage feedback from the datapath.
241 * Change state and re-schedule ourselves.
243 llentry_request_feedback(lle);
244 lle->ln_state = ARP_LLINFO_VERIFY;
245 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
249 case ARP_LLINFO_VERIFY:
250 if (llentry_get_hittime(lle) > 0 && lle->la_preempt > 0) {
251 /* Entry was used, issue refresh request */
252 struct epoch_tracker et;
255 dst = lle->r_l3addr.addr4;
257 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
260 arprequest(ifp, NULL, &dst, NULL);
265 /* Nothing happened. Reschedule if not too late */
266 if (lle->la_expire > time_uptime) {
267 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
273 case ARP_LLINFO_INCOMPLETE:
274 case ARP_LLINFO_DELETED:
278 if ((lle->la_flags & LLE_DELETED) == 0) {
281 if (lle->la_flags & LLE_VALID)
282 evt = LLENTRY_EXPIRED;
284 evt = LLENTRY_TIMEDOUT;
285 EVENTHANDLER_INVOKE(lle_event, lle, evt);
288 callout_stop(&lle->lle_timer);
290 /* XXX: LOR avoidance. We still have ref on lle. */
295 /* Guard against race with other llentry_free(). */
296 if (lle->la_flags & LLE_LINKED) {
298 lltable_unlink_entry(lle->lle_tbl, lle);
300 IF_AFDATA_UNLOCK(ifp);
302 size_t pkts_dropped = llentry_free(lle);
304 ARPSTAT_ADD(dropped, pkts_dropped);
305 ARPSTAT_INC(timeouts);
311 * Stores link-layer header for @ifp in format suitable for if_output()
312 * into buffer @buf. Resulting header length is stored in @bufsize.
314 * Returns 0 on success.
317 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf,
320 struct if_encap_req ereq;
323 bzero(buf, *bufsize);
324 bzero(&ereq, sizeof(ereq));
326 ereq.bufsize = *bufsize;
327 ereq.rtype = IFENCAP_LL;
328 ereq.family = AF_ARP;
329 ereq.lladdr = ar_tha(ah);
330 ereq.hdata = (u_char *)ah;
332 ereq.flags = IFENCAP_FLAG_BROADCAST;
333 error = ifp->if_requestencap(ifp, &ereq);
335 *bufsize = ereq.bufsize;
341 * Broadcast an ARP request. Caller specifies:
342 * - arp header source ip address
343 * - arp header target ip address
344 * - arp header source ethernet address
347 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip,
348 const struct in_addr *tip, u_char *enaddr)
353 u_char *carpaddr = NULL;
354 uint8_t linkhdr[LLE_MAX_LINKHDR];
363 * The caller did not supply a source address, try to find
364 * a compatible one among those assigned to this interface.
368 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
369 if (ifa->ifa_addr->sa_family != AF_INET)
373 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
375 sip = &IA_SIN(ifa)->sin_addr;
378 sip = &IA_SIN(ifa)->sin_addr;
381 if (0 == ((sip->s_addr ^ tip->s_addr) &
382 IA_MASKSIN(ifa)->sin_addr.s_addr))
383 break; /* found it. */
386 printf("%s: cannot find matching address\n", __func__);
387 return (EADDRNOTAVAIL);
391 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
393 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
395 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
397 m->m_pkthdr.len = m->m_len;
398 M_ALIGN(m, m->m_len);
399 ah = mtod(m, struct arphdr *);
400 bzero((caddr_t)ah, m->m_len);
402 mac_netinet_arp_send(ifp, m);
404 ah->ar_pro = htons(ETHERTYPE_IP);
405 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
406 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
407 ah->ar_op = htons(ARPOP_REQUEST);
408 bcopy(enaddr, ar_sha(ah), ah->ar_hln);
409 bcopy(sip, ar_spa(ah), ah->ar_pln);
410 bcopy(tip, ar_tpa(ah), ah->ar_pln);
411 sa.sa_family = AF_ARP;
414 /* Calculate link header for sending frame */
415 bzero(&ro, sizeof(ro));
416 linkhdrsize = sizeof(linkhdr);
417 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize);
418 if (error != 0 && error != EAFNOSUPPORT) {
420 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
421 if_name(ifp), error);
425 ro.ro_prepend = linkhdr;
426 ro.ro_plen = linkhdrsize;
429 m->m_flags |= M_BCAST;
430 m_clrprotoflags(m); /* Avoid confusing lower layers. */
431 error = (*ifp->if_output)(ifp, m, &sa, &ro);
432 ARPSTAT_INC(txrequests);
434 ARPSTAT_INC(txerrors);
435 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n",
436 if_name(ifp), error);
442 arprequest(struct ifnet *ifp, const struct in_addr *sip,
443 const struct in_addr *tip, u_char *enaddr)
446 (void) arprequest_internal(ifp, sip, tip, enaddr);
450 * Resolve an IP address into an ethernet address - heavy version.
451 * Used internally by arpresolve().
452 * We have already checked that we can't use an existing lle without
453 * modification so we have to acquire an LLE_EXCLUSIVE lle lock.
455 * On success, desten and pflags are filled in and the function returns 0;
456 * If the packet must be held pending resolution, we return EWOULDBLOCK
457 * On other errors, we return the corresponding error code.
458 * Note that m_freem() handles NULL.
461 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m,
462 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
463 struct llentry **plle)
465 struct llentry *la = NULL, *la_tmp;
477 if ((flags & LLE_CREATE) == 0)
478 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
479 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
480 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
482 char addrbuf[INET_ADDRSTRLEN];
485 "arpresolve: can't allocate llinfo for %s on %s\n",
486 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf),
492 IF_AFDATA_WLOCK(ifp);
494 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
495 /* Prefer ANY existing lle over newly-created one */
497 lltable_link_entry(LLTABLE(ifp), la);
498 IF_AFDATA_WUNLOCK(ifp);
499 if (la_tmp != NULL) {
500 lltable_free_entry(LLTABLE(ifp), la);
509 if ((la->la_flags & LLE_VALID) &&
510 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
511 if (flags & LLE_ADDRONLY) {
512 lladdr = la->ll_addr;
513 ll_len = ifp->if_addrlen;
515 lladdr = la->r_linkdata;
516 ll_len = la->r_hdrlen;
518 bcopy(lladdr, desten, ll_len);
520 /* Notify LLE code that the entry was used by datapath */
521 llentry_provide_feedback(la);
523 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR);
532 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
535 * There is an arptab entry, but no ethernet address
536 * response yet. Add the mbuf to the list, dropping
537 * the oldest packet if we have exceeded the system
541 size_t dropped = lltable_append_entry_queue(la, m, V_arp_maxhold);
542 ARPSTAT_ADD(dropped, dropped);
546 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
547 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
548 * if we have already sent arp_maxtries ARP requests. Retransmit the
549 * ARP request, but not faster than one request per second.
551 if (la->la_asked < V_arp_maxtries)
552 error = EWOULDBLOCK; /* First request. */
554 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN;
560 la->la_expire = time_uptime;
561 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down,
567 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL);
569 * Only overwrite 'error' in case of error; in case of success
570 * the proper return value was already set above.
582 * Lookups link header based on an IP address.
584 * ifp is the interface we use
585 * is_gw != 0 if @dst represents gateway to some destination
586 * m is the mbuf. May be NULL if we don't have a packet.
587 * dst is the next hop,
588 * desten is the storage to put LL header.
589 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR
591 * On success, full/partial link header and flags are filled in and
592 * the function returns 0.
593 * If the packet must be held pending resolution, we return EWOULDBLOCK
594 * On other errors, we return the corresponding error code.
595 * Note that m_freem() handles NULL.
598 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
599 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
600 struct llentry **plle)
602 struct llentry *la = NULL;
612 if (m->m_flags & M_BCAST) {
615 ifp->if_broadcastaddr, ifp->if_addrlen);
618 if (m->m_flags & M_MCAST) {
620 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
625 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst);
626 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) {
627 /* Entry found, let's copy lle info */
628 bcopy(la->r_linkdata, desten, la->r_hdrlen);
630 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR);
631 /* Notify the LLE handling code that the entry was used. */
632 llentry_provide_feedback(la);
643 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst,
644 desten, pflags, plle));
648 * Common length and type checks are done here,
649 * then the protocol-specific routine is called.
652 arpintr(struct mbuf *m)
659 ifp = m->m_pkthdr.rcvif;
661 if (m->m_len < sizeof(struct arphdr) &&
662 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
663 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n",
667 ar = mtod(m, struct arphdr *);
669 /* Check if length is sufficient */
670 if (m->m_len < arphdr_len(ar)) {
671 m = m_pullup(m, arphdr_len(ar));
673 ARP_LOG(LOG_NOTICE, "short packet received on %s\n",
677 ar = mtod(m, struct arphdr *);
682 switch (ntohs(ar->ar_hrd)) {
684 hlen = ETHER_ADDR_LEN; /* RFC 826 */
687 case ARPHRD_INFINIBAND:
688 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */
689 layer = "infiniband";
691 case ARPHRD_IEEE1394:
692 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */
696 * Restrict too long hardware addresses.
697 * Currently we are capable of handling 20-byte
698 * addresses ( sizeof(lle->ll_addr) )
700 if (ar->ar_hln >= 20)
705 "packet with unknown hardware format 0x%02d received on "
706 "%s\n", ntohs(ar->ar_hrd), if_name(ifp));
711 if (hlen != 0 && hlen != ar->ar_hln) {
713 "packet with invalid %s address length %d received on %s\n",
714 layer, ar->ar_hln, if_name(ifp));
719 ARPSTAT_INC(received);
720 switch (ntohs(ar->ar_pro)) {
732 * ARP for Internet protocols on 10 Mb/s Ethernet.
733 * Algorithm is that given in RFC 826.
734 * In addition, a sanity check is performed on the sender
735 * protocol address, to catch impersonators.
736 * We no longer handle negotiations for use of trailer protocol:
737 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
738 * along with IP replies if we wanted trailers sent to us,
739 * and also sent them in response to IP replies.
740 * This allowed either end to announce the desire to receive
742 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
743 * but formerly didn't normally send requests.
745 static int log_arp_wrong_iface = 1;
746 static int log_arp_movements = 1;
747 static int log_arp_permanent_modify = 1;
748 static int allow_multicast = 0;
750 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
751 &log_arp_wrong_iface, 0,
752 "log arp packets arriving on the wrong interface");
753 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
754 &log_arp_movements, 0,
755 "log arp replies from MACs different than the one in the cache");
756 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
757 &log_arp_permanent_modify, 0,
758 "log arp replies from MACs different than the one in the permanent arp entry");
759 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
760 &allow_multicast, 0, "accept multicast addresses");
763 in_arpinput(struct mbuf *m)
766 struct ifnet *ifp = m->m_pkthdr.rcvif;
767 struct llentry *la = NULL, *la_tmp;
769 struct in_ifaddr *ia;
771 struct in_addr isaddr, itaddr, myaddr;
772 u_int8_t *enaddr = NULL;
774 int bridged = 0, is_bridge = 0;
776 struct sockaddr_in sin;
777 struct sockaddr *dst;
778 struct nhop_object *nh;
779 uint8_t linkhdr[LLE_MAX_LINKHDR];
784 char addrbuf[INET_ADDRSTRLEN];
788 sin.sin_len = sizeof(struct sockaddr_in);
789 sin.sin_family = AF_INET;
790 sin.sin_addr.s_addr = 0;
794 if (ifp->if_type == IFT_BRIDGE)
798 * We already have checked that mbuf contains enough contiguous data
799 * to hold entire arp message according to the arp header.
801 ah = mtod(m, struct arphdr *);
804 * ARP is only for IPv4 so we can reject packets with
805 * a protocol length not equal to an IPv4 address.
807 if (ah->ar_pln != sizeof(struct in_addr)) {
808 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
809 sizeof(struct in_addr));
813 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
814 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
815 ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
819 op = ntohs(ah->ar_op);
820 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
821 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
823 if (op == ARPOP_REPLY)
824 ARPSTAT_INC(rxreplies);
827 * For a bridge, we want to check the address irrespective
828 * of the receive interface. (This will change slightly
829 * when we have clusters of interfaces).
831 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
832 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
833 ia->ia_ifp == ifp) &&
834 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
835 (ia->ia_ifa.ifa_carp == NULL ||
836 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
837 ifa_ref(&ia->ia_ifa);
841 CK_LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
842 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
843 ia->ia_ifp == ifp) &&
844 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
845 ifa_ref(&ia->ia_ifa);
849 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
850 (ia->ia_ifp->if_bridge == ifp->if_softc && \
851 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
852 addr == ia->ia_addr.sin_addr.s_addr)
854 * Check the case when bridge shares its MAC address with
855 * some of its children, so packets are claimed by bridge
856 * itself (bridge_input() does it first), but they are really
857 * meant to be destined to the bridge member.
860 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
861 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
862 ifa_ref(&ia->ia_ifa);
868 #undef BDG_MEMBER_MATCHES_ARP
871 * No match, use the first inet address on the receive interface
872 * as a dummy address for the rest of the function.
874 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
875 if (ifa->ifa_addr->sa_family == AF_INET &&
876 (ifa->ifa_carp == NULL ||
877 (*carp_iamatch_p)(ifa, &enaddr))) {
884 * If bridging, fall back to using any inet address.
886 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL)
888 ifa_ref(&ia->ia_ifa);
891 enaddr = (u_int8_t *)IF_LLADDR(ifp);
892 carped = (ia->ia_ifa.ifa_carp != NULL);
893 myaddr = ia->ia_addr.sin_addr;
894 ifa_free(&ia->ia_ifa);
895 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
896 goto drop; /* it's from me, ignore it. */
897 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
898 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
899 "%s!\n", inet_ntoa_r(isaddr, addrbuf));
903 if (ifp->if_addrlen != ah->ar_hln) {
904 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
905 "i/f %d (ignored)\n", ifp->if_addrlen,
906 (u_char *) ar_sha(ah), ":", ah->ar_hln,
912 * Warn if another host is using the same IP address, but only if the
913 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
914 * case we suppress the warning to avoid false positive complaints of
915 * potential misconfiguration.
917 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
918 myaddr.s_addr != 0) {
919 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
920 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
921 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname);
926 if (ifp->if_flags & IFF_STATICARP)
929 bzero(&sin, sizeof(sin));
930 sin.sin_len = sizeof(struct sockaddr_in);
931 sin.sin_family = AF_INET;
932 sin.sin_addr = isaddr;
933 dst = (struct sockaddr *)&sin;
934 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
936 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
937 else if (itaddr.s_addr == myaddr.s_addr) {
939 * Request/reply to our address, but no lle exists yet.
940 * Calculate full link prepend to use in lle.
942 linkhdrsize = sizeof(linkhdr);
943 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
944 &linkhdrsize, &lladdr_off) != 0)
947 /* Allocate new entry */
948 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
951 * lle creation may fail if source address belongs
952 * to non-directly connected subnet. However, we
953 * will try to answer the request instead of dropping
958 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
961 IF_AFDATA_WLOCK(ifp);
963 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
966 * Check if lle still does not exists.
967 * If it does, that means that we either
968 * 1) have configured it explicitly, via
969 * 1a) 'arp -s' static entry or
970 * 1b) interface address static record
972 * 2) it was the result of sending first packet to-host
974 * 3) it was another arp reply packet we handled in
977 * In all cases except 3) we definitely need to prefer
978 * existing lle. For the sake of simplicity, prefer any
979 * existing lle over newly-create one.
982 lltable_link_entry(LLTABLE(ifp), la);
983 IF_AFDATA_WUNLOCK(ifp);
985 if (la_tmp == NULL) {
986 arp_mark_lle_reachable(la, ifp);
989 /* Free newly-create entry and handle packet */
990 lltable_free_entry(LLTABLE(ifp), la);
993 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
994 /* arp_check_update_lle() returns @la unlocked */
999 if (op != ARPOP_REQUEST)
1001 ARPSTAT_INC(rxrequests);
1003 if (itaddr.s_addr == myaddr.s_addr) {
1004 /* Shortcut.. the receiving interface is the target. */
1005 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1006 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1009 * Destination address is not ours. Check if
1010 * proxyarp entry exists or proxyarp is turned on globally.
1012 struct llentry *lle;
1014 sin.sin_addr = itaddr;
1015 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
1017 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
1018 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1019 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln);
1025 if (!V_arp_proxyall)
1029 nh = fib4_lookup(ifp->if_fib, itaddr, 0, 0, 0);
1034 * Don't send proxies for nodes on the same interface
1035 * as this one came out of, or we'll get into a fight
1036 * over who claims what Ether address.
1038 if (nh->nh_ifp == ifp)
1041 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1042 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1045 * Also check that the node which sent the ARP packet
1046 * is on the interface we expect it to be on. This
1047 * avoids ARP chaos if an interface is connected to the
1051 nh = fib4_lookup(ifp->if_fib, isaddr, 0, 0, 0);
1054 if (nh->nh_ifp != ifp) {
1055 ARP_LOG(LOG_INFO, "proxy: ignoring request"
1056 " from %s via %s\n",
1057 inet_ntoa_r(isaddr, addrbuf),
1063 printf("arp: proxying for %s\n",
1064 inet_ntoa_r(itaddr, addrbuf));
1069 if (itaddr.s_addr == myaddr.s_addr &&
1070 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
1071 /* RFC 3927 link-local IPv4; always reply by broadcast. */
1072 #ifdef DEBUG_LINKLOCAL
1073 printf("arp: sending reply for link-local addr %s\n",
1074 inet_ntoa_r(itaddr, addrbuf));
1076 m->m_flags |= M_BCAST;
1077 m->m_flags &= ~M_MCAST;
1079 /* default behaviour; never reply by broadcast. */
1080 m->m_flags &= ~(M_BCAST|M_MCAST);
1082 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
1083 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
1084 ah->ar_op = htons(ARPOP_REPLY);
1085 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
1086 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
1087 m->m_pkthdr.len = m->m_len;
1088 m->m_pkthdr.rcvif = NULL;
1089 sa.sa_family = AF_ARP;
1092 /* Calculate link header for sending frame */
1093 bzero(&ro, sizeof(ro));
1094 linkhdrsize = sizeof(linkhdr);
1095 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize);
1098 * arp_fillheader() may fail due to lack of support inside encap request
1099 * routing. This is not necessary an error, AF_ARP can/should be handled
1102 if (error != 0 && error != EAFNOSUPPORT) {
1103 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
1104 if_name(ifp), error);
1108 ro.ro_prepend = linkhdr;
1109 ro.ro_plen = linkhdrsize;
1112 m_clrprotoflags(m); /* Avoid confusing lower layers. */
1113 (*ifp->if_output)(ifp, m, &sa, &ro);
1114 ARPSTAT_INC(txreplies);
1122 static struct mbuf *
1123 arp_grab_holdchain(struct llentry *la)
1127 LLE_WLOCK_ASSERT(la);
1129 chain = la->la_hold;
1137 arp_flush_holdchain(struct ifnet *ifp, struct llentry *la, struct mbuf *chain)
1139 struct mbuf *m_hold, *m_hold_next;
1140 struct sockaddr_in sin;
1145 .ro_prepend = la->r_linkdata,
1146 .ro_plen = la->r_hdrlen,
1149 lltable_fill_sa_entry(la, (struct sockaddr *)&sin);
1151 for (m_hold = chain; m_hold != NULL; m_hold = m_hold_next) {
1152 m_hold_next = m_hold->m_nextpkt;
1153 m_hold->m_nextpkt = NULL;
1154 /* Avoid confusing lower layers. */
1155 m_clrprotoflags(m_hold);
1156 (*ifp->if_output)(ifp, m_hold, (struct sockaddr *)&sin, &ro);
1161 * Checks received arp data against existing @la.
1162 * Updates lle state/performs notification if necessary.
1165 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp,
1166 int bridged, struct llentry *la)
1168 uint8_t linkhdr[LLE_MAX_LINKHDR];
1171 char addrbuf[INET_ADDRSTRLEN];
1173 LLE_WLOCK_ASSERT(la);
1175 /* the following is not an error when doing bridging */
1176 if (!bridged && la->lle_tbl->llt_ifp != ifp) {
1177 if (log_arp_wrong_iface)
1178 ARP_LOG(LOG_WARNING, "%s is on %s "
1179 "but got reply from %*D on %s\n",
1180 inet_ntoa_r(isaddr, addrbuf),
1181 la->lle_tbl->llt_ifp->if_xname,
1182 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1187 if ((la->la_flags & LLE_VALID) &&
1188 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) {
1189 if (la->la_flags & LLE_STATIC) {
1191 if (log_arp_permanent_modify)
1193 "%*D attempts to modify "
1194 "permanent entry for %s on %s\n",
1196 (u_char *)ar_sha(ah), ":",
1197 inet_ntoa_r(isaddr, addrbuf),
1201 if (log_arp_movements) {
1202 ARP_LOG(LOG_INFO, "%s moved from %*D "
1204 inet_ntoa_r(isaddr, addrbuf),
1206 (u_char *)la->ll_addr, ":",
1207 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1212 /* Calculate full link prepend to use in lle */
1213 linkhdrsize = sizeof(linkhdr);
1214 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
1215 &linkhdrsize, &lladdr_off) != 0) {
1220 /* Check if something has changed */
1221 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 ||
1222 (la->la_flags & LLE_VALID) == 0) {
1223 /* Try to perform LLE update */
1224 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
1230 /* Clear fast path feedback request if set */
1231 llentry_mark_used(la);
1234 arp_mark_lle_reachable(la, ifp);
1237 * The packets are all freed within the call to the output
1240 * NB: The lock MUST be released before the call to the
1243 if (la->la_hold != NULL) {
1246 chain = arp_grab_holdchain(la);
1248 arp_flush_holdchain(ifp, la, chain);
1254 arp_mark_lle_reachable(struct llentry *la, struct ifnet *ifp)
1256 int canceled, wtime;
1258 LLE_WLOCK_ASSERT(la);
1260 la->ln_state = ARP_LLINFO_REACHABLE;
1261 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
1263 if ((ifp->if_flags & IFF_STICKYARP) != 0)
1264 la->la_flags |= LLE_STATIC;
1266 if (!(la->la_flags & LLE_STATIC)) {
1268 la->la_expire = time_uptime + V_arpt_keep;
1269 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit;
1271 wtime = V_arpt_keep;
1272 canceled = callout_reset(&la->lle_timer,
1273 hz * wtime, arptimer, la);
1278 la->la_preempt = V_arp_maxtries;
1282 * Add permanent link-layer record for given interface address.
1284 static __noinline void
1285 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst)
1287 struct llentry *lle, *lle_tmp;
1290 * Interface address LLE record is considered static
1291 * because kernel code relies on LLE_STATIC flag to check
1292 * if these entries can be rewriten by arp updates.
1294 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst);
1296 log(LOG_INFO, "arp_ifinit: cannot create arp "
1297 "entry for interface address\n");
1301 IF_AFDATA_WLOCK(ifp);
1303 /* Unlink any entry if exists */
1304 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1305 if (lle_tmp != NULL)
1306 lltable_unlink_entry(LLTABLE(ifp), lle_tmp);
1308 lltable_link_entry(LLTABLE(ifp), lle);
1309 IF_AFDATA_WUNLOCK(ifp);
1311 if (lle_tmp != NULL)
1312 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED);
1314 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED);
1316 if (lle_tmp != NULL)
1317 lltable_free_entry(LLTABLE(ifp), lle_tmp);
1321 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range
1325 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS)
1328 int rexmit_count = *(int *)arg1;
1330 error = sysctl_handle_int(oidp, &rexmit_count, 0, req);
1332 /* Enforce limits on any new value that may have been set. */
1333 if (!error && req->newptr) {
1334 /* A new value was set. */
1335 if (rexmit_count < 0) {
1337 } else if (rexmit_count > MAX_GARP_RETRANSMITS) {
1338 rexmit_count = MAX_GARP_RETRANSMITS;
1340 *(int *)arg1 = rexmit_count;
1347 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to
1348 * retransmit it again. A pending callout owns a reference to the ifa.
1351 garp_rexmit(void *arg)
1353 struct in_ifaddr *ia = arg;
1355 if (callout_pending(&ia->ia_garp_timer) ||
1356 !callout_active(&ia->ia_garp_timer)) {
1357 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1358 ifa_free(&ia->ia_ifa);
1362 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet);
1365 * Drop lock while the ARP request is generated.
1367 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1369 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr,
1370 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp));
1373 * Increment the count of retransmissions. If the count has reached the
1374 * maximum value, stop sending the GARP packets. Otherwise, schedule
1375 * the callout to retransmit another GARP packet.
1377 ++ia->ia_garp_count;
1378 if (ia->ia_garp_count >= garp_rexmit_count) {
1379 ifa_free(&ia->ia_ifa);
1382 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1383 rescheduled = callout_reset(&ia->ia_garp_timer,
1384 (1 << ia->ia_garp_count) * hz,
1386 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1388 ifa_free(&ia->ia_ifa);
1396 * Start the GARP retransmit timer.
1398 * A single GARP is always transmitted when an IPv4 address is added
1399 * to an interface and that is usually sufficient. However, in some
1400 * circumstances, such as when a shared address is passed between
1401 * cluster nodes, this single GARP may occasionally be dropped or
1402 * lost. This can lead to neighbors on the network link working with a
1403 * stale ARP cache and sending packets destined for that address to
1404 * the node that previously owned the address, which may not respond.
1406 * To avoid this situation, GARP retransmits can be enabled by setting
1407 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater
1408 * than zero. The setting represents the maximum number of
1409 * retransmissions. The interval between retransmissions is calculated
1410 * using an exponential backoff algorithm, doubling each time, so the
1411 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds).
1414 garp_timer_start(struct ifaddr *ifa)
1416 struct in_ifaddr *ia = (struct in_ifaddr *) ifa;
1418 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1419 ia->ia_garp_count = 0;
1420 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz,
1421 garp_rexmit, ia) == 0) {
1424 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1428 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
1430 struct epoch_tracker et;
1431 const struct sockaddr_in *dst_in;
1432 const struct sockaddr *dst;
1434 if (ifa->ifa_carp != NULL)
1437 dst = ifa->ifa_addr;
1438 dst_in = (const struct sockaddr_in *)dst;
1440 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY)
1442 NET_EPOCH_ENTER(et);
1443 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp));
1445 if (garp_rexmit_count > 0) {
1446 garp_timer_start(ifa);
1449 arp_add_ifa_lle(ifp, dst);
1453 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr)
1456 if (ntohl(addr.s_addr) != INADDR_ANY)
1457 arprequest(ifp, &addr, &addr, enaddr);
1461 * Sends gratuitous ARPs for each ifaddr to notify other
1462 * nodes about the address change.
1464 static __noinline void
1465 arp_handle_ifllchange(struct ifnet *ifp)
1469 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
1470 if (ifa->ifa_addr->sa_family == AF_INET)
1471 arp_ifinit(ifp, ifa);
1476 * A handler for interface link layer address change event.
1479 arp_iflladdr(void *arg __unused, struct ifnet *ifp)
1481 /* if_bridge can update its lladdr during if_vmove(), after we've done
1482 * if_detach_internal()/dom_ifdetach(). */
1483 if (ifp->if_afdata[AF_INET] == NULL)
1486 lltable_update_ifaddr(LLTABLE(ifp));
1488 if ((ifp->if_flags & IFF_UP) != 0)
1489 arp_handle_ifllchange(ifp);
1496 if (IS_DEFAULT_VNET(curvnet)) {
1497 netisr_register(&arp_nh);
1498 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event,
1499 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY);
1503 netisr_register_vnet(&arp_nh);
1506 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND,
1511 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH
1512 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5.
1515 vnet_arp_destroy(__unused void *arg)
1518 netisr_unregister_vnet(&arp_nh);
1520 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1521 vnet_arp_destroy, NULL);