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>
41 __FBSDID("$FreeBSD$");
45 #include <sys/param.h>
46 #include <sys/eventhandler.h>
47 #include <sys/kernel.h>
49 #include <sys/queue.h>
50 #include <sys/sysctl.h>
51 #include <sys/systm.h>
53 #include <sys/malloc.h>
55 #include <sys/rmlock.h>
56 #include <sys/socket.h>
57 #include <sys/syslog.h>
60 #include <net/if_var.h>
61 #include <net/if_dl.h>
62 #include <net/if_types.h>
63 #include <net/netisr.h>
64 #include <net/ethernet.h>
65 #include <net/route.h>
68 #include <netinet/in.h>
69 #include <netinet/in_fib.h>
70 #include <netinet/in_var.h>
71 #include <net/if_llatbl.h>
72 #include <netinet/if_ether.h>
74 #include <netinet/ip_carp.h>
77 #include <security/mac/mac_framework.h>
79 #define SIN(s) ((const struct sockaddr_in *)(s))
81 static struct timeval arp_lastlog;
82 static int arp_curpps;
83 static int arp_maxpps = 1;
85 /* Simple ARP state machine */
86 enum arp_llinfo_state {
87 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */
88 ARP_LLINFO_REACHABLE, /* LLE is valid */
89 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */
90 ARP_LLINFO_DELETED, /* LLE is deleted */
93 SYSCTL_DECL(_net_link_ether);
94 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
95 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, "");
98 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20
100 VNET_DEFINE_STATIC(int, arp_maxtries) = 5;
101 VNET_DEFINE_STATIC(int, arp_proxyall) = 0;
102 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for
104 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/
105 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */
106 VNET_PCPUSTAT_SYSINIT(arpstat);
109 VNET_PCPUSTAT_SYSUNINIT(arpstat);
112 VNET_DEFINE_STATIC(int, arp_maxhold) = 1;
114 #define V_arpt_keep VNET(arpt_keep)
115 #define V_arpt_down VNET(arpt_down)
116 #define V_arpt_rexmit VNET(arpt_rexmit)
117 #define V_arp_maxtries VNET(arp_maxtries)
118 #define V_arp_proxyall VNET(arp_proxyall)
119 #define V_arp_maxhold VNET(arp_maxhold)
121 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW,
122 &VNET_NAME(arpt_keep), 0,
123 "ARP entry lifetime in seconds");
124 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW,
125 &VNET_NAME(arp_maxtries), 0,
126 "ARP resolution attempts before returning error");
127 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW,
128 &VNET_NAME(arp_proxyall), 0,
129 "Enable proxy ARP for all suitable requests");
130 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW,
131 &VNET_NAME(arpt_down), 0,
132 "Incomplete ARP entry lifetime in seconds");
133 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat,
134 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)");
135 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW,
136 &VNET_NAME(arp_maxhold), 0,
137 "Number of packets to hold per ARP entry");
138 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second,
139 CTLFLAG_RW, &arp_maxpps, 0,
140 "Maximum number of remotely triggered ARP messages that can be "
141 "logged per second");
144 * Due to the exponential backoff algorithm used for the interval between GARP
145 * retransmissions, the maximum number of retransmissions is limited for
146 * sanity. This limit corresponds to a maximum interval between retransmissions
147 * of 2^16 seconds ~= 18 hours.
149 * Making this limit more dynamic is more complicated than worthwhile,
150 * especially since sending out GARPs spaced days apart would be of little
151 * use. A maximum dynamic limit would look something like:
153 * const int max = fls(INT_MAX / hz) - 1;
155 #define MAX_GARP_RETRANSMITS 16
156 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS);
157 static int garp_rexmit_count = 0; /* GARP retransmission setting. */
159 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count,
160 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE,
161 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I",
162 "Number of times to retransmit GARP packets;"
163 " 0 to disable, maximum of 16");
165 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */
166 #define V_arp_log_level VNET(arp_log_level)
167 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW,
168 &VNET_NAME(arp_log_level), 0,
169 "Minimum log(9) level for recording rate limited arp log messages. "
170 "The higher will be log more (emerg=0, info=6 (default), debug=7).");
171 #define ARP_LOG(pri, ...) do { \
172 if ((pri) <= V_arp_log_level && \
173 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \
174 log((pri), "arp: " __VA_ARGS__); \
178 static void arpintr(struct mbuf *);
179 static void arptimer(void *);
181 static void in_arpinput(struct mbuf *);
184 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr,
185 struct ifnet *ifp, int bridged, struct llentry *la);
186 static void arp_mark_lle_reachable(struct llentry *la);
187 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp);
189 static eventhandler_tag iflladdr_tag;
191 static const struct netisr_handler arp_nh = {
193 .nh_handler = arpintr,
194 .nh_proto = NETISR_ARP,
195 .nh_policy = NETISR_POLICY_SOURCE,
199 * Timeout routine. Age arp_tab entries periodically.
204 struct llentry *lle = (struct llentry *)arg;
208 if (lle->la_flags & LLE_STATIC) {
212 if (callout_pending(&lle->lle_timer)) {
214 * Here we are a bit odd here in the treatment of
215 * active/pending. If the pending bit is set, it got
216 * rescheduled before I ran. The active
217 * bit we ignore, since if it was stopped
218 * in ll_tablefree() and was currently running
219 * it would have return 0 so the code would
220 * not have deleted it since the callout could
221 * not be stopped so we want to go through
222 * with the delete here now. If the callout
223 * was restarted, the pending bit will be back on and
224 * we just want to bail since the callout_reset would
225 * return 1 and our reference would have been removed
226 * by arpresolve() below.
231 ifp = lle->lle_tbl->llt_ifp;
232 CURVNET_SET(ifp->if_vnet);
234 switch (lle->ln_state) {
235 case ARP_LLINFO_REACHABLE:
238 * Expiration time is approaching.
239 * Let's try to refresh entry if it is still
242 * Set r_skip_req to get feedback from
243 * fast path. Change state and re-schedule
249 lle->ln_state = ARP_LLINFO_VERIFY;
250 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
254 case ARP_LLINFO_VERIFY:
256 r_skip_req = lle->r_skip_req;
259 if (r_skip_req == 0 && lle->la_preempt > 0) {
260 /* Entry was used, issue refresh request */
262 dst = lle->r_l3addr.addr4;
264 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
266 arprequest(ifp, NULL, &dst, NULL);
270 /* Nothing happened. Reschedule if not too late */
271 if (lle->la_expire > time_uptime) {
272 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
278 case ARP_LLINFO_INCOMPLETE:
279 case ARP_LLINFO_DELETED:
283 if ((lle->la_flags & LLE_DELETED) == 0) {
286 if (lle->la_flags & LLE_VALID)
287 evt = LLENTRY_EXPIRED;
289 evt = LLENTRY_TIMEDOUT;
290 EVENTHANDLER_INVOKE(lle_event, lle, evt);
293 callout_stop(&lle->lle_timer);
295 /* XXX: LOR avoidance. We still have ref on lle. */
300 /* Guard against race with other llentry_free(). */
301 if (lle->la_flags & LLE_LINKED) {
303 lltable_unlink_entry(lle->lle_tbl, lle);
305 IF_AFDATA_UNLOCK(ifp);
307 size_t pkts_dropped = llentry_free(lle);
309 ARPSTAT_ADD(dropped, pkts_dropped);
310 ARPSTAT_INC(timeouts);
316 * Stores link-layer header for @ifp in format suitable for if_output()
317 * into buffer @buf. Resulting header length is stored in @bufsize.
319 * Returns 0 on success.
322 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf,
325 struct if_encap_req ereq;
328 bzero(buf, *bufsize);
329 bzero(&ereq, sizeof(ereq));
331 ereq.bufsize = *bufsize;
332 ereq.rtype = IFENCAP_LL;
333 ereq.family = AF_ARP;
334 ereq.lladdr = ar_tha(ah);
335 ereq.hdata = (u_char *)ah;
337 ereq.flags = IFENCAP_FLAG_BROADCAST;
338 error = ifp->if_requestencap(ifp, &ereq);
340 *bufsize = ereq.bufsize;
347 * Broadcast an ARP request. Caller specifies:
348 * - arp header source ip address
349 * - arp header target ip address
350 * - arp header source ethernet address
353 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip,
354 const struct in_addr *tip, u_char *enaddr)
359 u_char *carpaddr = NULL;
360 uint8_t linkhdr[LLE_MAX_LINKHDR];
367 * The caller did not supply a source address, try to find
368 * a compatible one among those assigned to this interface.
370 struct epoch_tracker et;
374 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
375 if (ifa->ifa_addr->sa_family != AF_INET)
379 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
381 sip = &IA_SIN(ifa)->sin_addr;
384 sip = &IA_SIN(ifa)->sin_addr;
387 if (0 == ((sip->s_addr ^ tip->s_addr) &
388 IA_MASKSIN(ifa)->sin_addr.s_addr))
389 break; /* found it. */
393 printf("%s: cannot find matching address\n", __func__);
394 return (EADDRNOTAVAIL);
398 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
400 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
402 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
404 m->m_pkthdr.len = m->m_len;
405 M_ALIGN(m, m->m_len);
406 ah = mtod(m, struct arphdr *);
407 bzero((caddr_t)ah, m->m_len);
409 mac_netinet_arp_send(ifp, m);
411 ah->ar_pro = htons(ETHERTYPE_IP);
412 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
413 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
414 ah->ar_op = htons(ARPOP_REQUEST);
415 bcopy(enaddr, ar_sha(ah), ah->ar_hln);
416 bcopy(sip, ar_spa(ah), ah->ar_pln);
417 bcopy(tip, ar_tpa(ah), ah->ar_pln);
418 sa.sa_family = AF_ARP;
421 /* Calculate link header for sending frame */
422 bzero(&ro, sizeof(ro));
423 linkhdrsize = sizeof(linkhdr);
424 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize);
425 if (error != 0 && error != EAFNOSUPPORT) {
426 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
427 if_name(ifp), error);
431 ro.ro_prepend = linkhdr;
432 ro.ro_plen = linkhdrsize;
435 m->m_flags |= M_BCAST;
436 m_clrprotoflags(m); /* Avoid confusing lower layers. */
437 error = (*ifp->if_output)(ifp, m, &sa, &ro);
438 ARPSTAT_INC(txrequests);
440 ARPSTAT_INC(txerrors);
441 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n",
442 if_name(ifp), error);
448 arprequest(struct ifnet *ifp, const struct in_addr *sip,
449 const struct in_addr *tip, u_char *enaddr)
452 (void) arprequest_internal(ifp, sip, tip, enaddr);
456 * Resolve an IP address into an ethernet address - heavy version.
457 * Used internally by arpresolve().
458 * We have already checked that we can't use an existing lle without
459 * modification so we have to acquire an LLE_EXCLUSIVE lle lock.
461 * On success, desten and pflags are filled in and the function returns 0;
462 * If the packet must be held pending resolution, we return EWOULDBLOCK
463 * On other errors, we return the corresponding error code.
464 * Note that m_freem() handles NULL.
467 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m,
468 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
469 struct llentry **plle)
471 struct llentry *la = NULL, *la_tmp;
472 struct mbuf *curr = NULL;
473 struct mbuf *next = NULL;
483 if ((flags & LLE_CREATE) == 0) {
484 struct epoch_tracker et;
487 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
490 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
491 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
493 char addrbuf[INET_ADDRSTRLEN];
496 "arpresolve: can't allocate llinfo for %s on %s\n",
497 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf),
503 IF_AFDATA_WLOCK(ifp);
505 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
506 /* Prefer ANY existing lle over newly-created one */
508 lltable_link_entry(LLTABLE(ifp), la);
509 IF_AFDATA_WUNLOCK(ifp);
510 if (la_tmp != NULL) {
511 lltable_free_entry(LLTABLE(ifp), la);
520 if ((la->la_flags & LLE_VALID) &&
521 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
522 if (flags & LLE_ADDRONLY) {
523 lladdr = la->ll_addr;
524 ll_len = ifp->if_addrlen;
526 lladdr = la->r_linkdata;
527 ll_len = la->r_hdrlen;
529 bcopy(lladdr, desten, ll_len);
531 /* Notify LLE code that the entry was used by datapath */
532 llentry_mark_used(la);
534 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR);
543 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
545 * There is an arptab entry, but no ethernet address
546 * response yet. Add the mbuf to the list, dropping
547 * the oldest packet if we have exceeded the system
551 if (la->la_numheld >= V_arp_maxhold) {
552 if (la->la_hold != NULL) {
553 next = la->la_hold->m_nextpkt;
554 m_freem(la->la_hold);
557 ARPSTAT_INC(dropped);
560 if (la->la_hold != NULL) {
562 while (curr->m_nextpkt != NULL)
563 curr = curr->m_nextpkt;
570 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
571 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
572 * if we have already sent arp_maxtries ARP requests. Retransmit the
573 * ARP request, but not faster than one request per second.
575 if (la->la_asked < V_arp_maxtries)
576 error = EWOULDBLOCK; /* First request. */
578 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN;
584 la->la_expire = time_uptime;
585 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down,
591 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL);
593 * Only overwrite 'error' in case of error; in case of success
594 * the proper return value was already set above.
606 * Lookups link header based on an IP address.
608 * ifp is the interface we use
609 * is_gw != 0 if @dst represents gateway to some destination
610 * m is the mbuf. May be NULL if we don't have a packet.
611 * dst is the next hop,
612 * desten is the storage to put LL header.
613 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR
615 * On success, full/partial link header and flags are filled in and
616 * the function returns 0.
617 * If the packet must be held pending resolution, we return EWOULDBLOCK
618 * On other errors, we return the corresponding error code.
619 * Note that m_freem() handles NULL.
622 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
623 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
624 struct llentry **plle)
626 struct epoch_tracker et;
627 struct llentry *la = NULL;
635 if (m->m_flags & M_BCAST) {
638 ifp->if_broadcastaddr, ifp->if_addrlen);
641 if (m->m_flags & M_MCAST) {
643 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
649 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst);
650 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) {
651 /* Entry found, let's copy lle info */
652 bcopy(la->r_linkdata, desten, la->r_hdrlen);
654 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR);
655 /* Notify the LLE handling code that the entry was used. */
656 llentry_mark_used(la);
669 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst,
670 desten, pflags, plle));
674 * Common length and type checks are done here,
675 * then the protocol-specific routine is called.
678 arpintr(struct mbuf *m)
685 ifp = m->m_pkthdr.rcvif;
687 if (m->m_len < sizeof(struct arphdr) &&
688 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
689 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n",
693 ar = mtod(m, struct arphdr *);
695 /* Check if length is sufficient */
696 if (m->m_len < arphdr_len(ar)) {
697 m = m_pullup(m, arphdr_len(ar));
699 ARP_LOG(LOG_NOTICE, "short packet received on %s\n",
703 ar = mtod(m, struct arphdr *);
708 switch (ntohs(ar->ar_hrd)) {
710 hlen = ETHER_ADDR_LEN; /* RFC 826 */
713 case ARPHRD_INFINIBAND:
714 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */
715 layer = "infiniband";
717 case ARPHRD_IEEE1394:
718 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */
722 * Restrict too long hardware addresses.
723 * Currently we are capable of handling 20-byte
724 * addresses ( sizeof(lle->ll_addr) )
726 if (ar->ar_hln >= 20)
731 "packet with unknown hardware format 0x%02d received on "
732 "%s\n", ntohs(ar->ar_hrd), if_name(ifp));
737 if (hlen != 0 && hlen != ar->ar_hln) {
739 "packet with invalid %s address length %d received on %s\n",
740 layer, ar->ar_hln, if_name(ifp));
745 ARPSTAT_INC(received);
746 switch (ntohs(ar->ar_pro)) {
758 * ARP for Internet protocols on 10 Mb/s Ethernet.
759 * Algorithm is that given in RFC 826.
760 * In addition, a sanity check is performed on the sender
761 * protocol address, to catch impersonators.
762 * We no longer handle negotiations for use of trailer protocol:
763 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
764 * along with IP replies if we wanted trailers sent to us,
765 * and also sent them in response to IP replies.
766 * This allowed either end to announce the desire to receive
768 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
769 * but formerly didn't normally send requests.
771 static int log_arp_wrong_iface = 1;
772 static int log_arp_movements = 1;
773 static int log_arp_permanent_modify = 1;
774 static int allow_multicast = 0;
776 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
777 &log_arp_wrong_iface, 0,
778 "log arp packets arriving on the wrong interface");
779 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
780 &log_arp_movements, 0,
781 "log arp replies from MACs different than the one in the cache");
782 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
783 &log_arp_permanent_modify, 0,
784 "log arp replies from MACs different than the one in the permanent arp entry");
785 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
786 &allow_multicast, 0, "accept multicast addresses");
789 in_arpinput(struct mbuf *m)
791 struct rm_priotracker in_ifa_tracker;
793 struct ifnet *ifp = m->m_pkthdr.rcvif;
794 struct llentry *la = NULL, *la_tmp;
796 struct in_ifaddr *ia;
798 struct in_addr isaddr, itaddr, myaddr;
799 u_int8_t *enaddr = NULL;
801 int bridged = 0, is_bridge = 0;
803 struct sockaddr_in sin;
804 struct sockaddr *dst;
805 struct nhop4_basic nh4;
806 uint8_t linkhdr[LLE_MAX_LINKHDR];
811 char addrbuf[INET_ADDRSTRLEN];
812 struct epoch_tracker et;
814 sin.sin_len = sizeof(struct sockaddr_in);
815 sin.sin_family = AF_INET;
816 sin.sin_addr.s_addr = 0;
820 if (ifp->if_type == IFT_BRIDGE)
824 * We already have checked that mbuf contains enough contiguous data
825 * to hold entire arp message according to the arp header.
827 ah = mtod(m, struct arphdr *);
830 * ARP is only for IPv4 so we can reject packets with
831 * a protocol length not equal to an IPv4 address.
833 if (ah->ar_pln != sizeof(struct in_addr)) {
834 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
835 sizeof(struct in_addr));
839 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
840 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
841 ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
845 op = ntohs(ah->ar_op);
846 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
847 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
849 if (op == ARPOP_REPLY)
850 ARPSTAT_INC(rxreplies);
853 * For a bridge, we want to check the address irrespective
854 * of the receive interface. (This will change slightly
855 * when we have clusters of interfaces).
857 IN_IFADDR_RLOCK(&in_ifa_tracker);
858 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
859 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
860 ia->ia_ifp == ifp) &&
861 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
862 (ia->ia_ifa.ifa_carp == NULL ||
863 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
864 ifa_ref(&ia->ia_ifa);
865 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
869 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
870 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
871 ia->ia_ifp == ifp) &&
872 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
873 ifa_ref(&ia->ia_ifa);
874 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
878 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
879 (ia->ia_ifp->if_bridge == ifp->if_softc && \
880 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
881 addr == ia->ia_addr.sin_addr.s_addr)
883 * Check the case when bridge shares its MAC address with
884 * some of its children, so packets are claimed by bridge
885 * itself (bridge_input() does it first), but they are really
886 * meant to be destined to the bridge member.
889 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
890 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
891 ifa_ref(&ia->ia_ifa);
893 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
898 #undef BDG_MEMBER_MATCHES_ARP
899 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
902 * No match, use the first inet address on the receive interface
903 * as a dummy address for the rest of the function.
906 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
907 if (ifa->ifa_addr->sa_family == AF_INET &&
908 (ifa->ifa_carp == NULL ||
909 (*carp_iamatch_p)(ifa, &enaddr))) {
918 * If bridging, fall back to using any inet address.
920 IN_IFADDR_RLOCK(&in_ifa_tracker);
921 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
922 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
925 ifa_ref(&ia->ia_ifa);
926 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
929 enaddr = (u_int8_t *)IF_LLADDR(ifp);
930 carped = (ia->ia_ifa.ifa_carp != NULL);
931 myaddr = ia->ia_addr.sin_addr;
932 ifa_free(&ia->ia_ifa);
933 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
934 goto drop; /* it's from me, ignore it. */
935 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
936 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
937 "%s!\n", inet_ntoa_r(isaddr, addrbuf));
941 if (ifp->if_addrlen != ah->ar_hln) {
942 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
943 "i/f %d (ignored)\n", ifp->if_addrlen,
944 (u_char *) ar_sha(ah), ":", ah->ar_hln,
950 * Warn if another host is using the same IP address, but only if the
951 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
952 * case we suppress the warning to avoid false positive complaints of
953 * potential misconfiguration.
955 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
956 myaddr.s_addr != 0) {
957 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
958 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
959 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname);
964 if (ifp->if_flags & IFF_STATICARP)
967 bzero(&sin, sizeof(sin));
968 sin.sin_len = sizeof(struct sockaddr_in);
969 sin.sin_family = AF_INET;
970 sin.sin_addr = isaddr;
971 dst = (struct sockaddr *)&sin;
973 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
976 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
977 else if (itaddr.s_addr == myaddr.s_addr) {
979 * Request/reply to our address, but no lle exists yet.
980 * Calculate full link prepend to use in lle.
982 linkhdrsize = sizeof(linkhdr);
983 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
984 &linkhdrsize, &lladdr_off) != 0)
987 /* Allocate new entry */
988 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
992 * lle creation may fail if source address belongs
993 * to non-directly connected subnet. However, we
994 * will try to answer the request instead of dropping
999 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
1002 IF_AFDATA_WLOCK(ifp);
1004 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1007 * Check if lle still does not exists.
1008 * If it does, that means that we either
1009 * 1) have configured it explicitly, via
1010 * 1a) 'arp -s' static entry or
1011 * 1b) interface address static record
1013 * 2) it was the result of sending first packet to-host
1015 * 3) it was another arp reply packet we handled in
1018 * In all cases except 3) we definitely need to prefer
1019 * existing lle. For the sake of simplicity, prefer any
1020 * existing lle over newly-create one.
1023 lltable_link_entry(LLTABLE(ifp), la);
1024 IF_AFDATA_WUNLOCK(ifp);
1026 if (la_tmp == NULL) {
1027 arp_mark_lle_reachable(la);
1030 /* Free newly-create entry and handle packet */
1031 lltable_free_entry(LLTABLE(ifp), la);
1034 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
1035 /* arp_check_update_lle() returns @la unlocked */
1040 if (op != ARPOP_REQUEST)
1042 ARPSTAT_INC(rxrequests);
1044 if (itaddr.s_addr == myaddr.s_addr) {
1045 /* Shortcut.. the receiving interface is the target. */
1046 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1047 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1049 struct llentry *lle = NULL;
1051 sin.sin_addr = itaddr;
1052 NET_EPOCH_ENTER(et);
1053 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
1056 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
1057 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1058 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln);
1065 if (!V_arp_proxyall)
1068 /* XXX MRT use table 0 for arp reply */
1069 if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0)
1073 * Don't send proxies for nodes on the same interface
1074 * as this one came out of, or we'll get into a fight
1075 * over who claims what Ether address.
1077 if (nh4.nh_ifp == ifp)
1080 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1081 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1084 * Also check that the node which sent the ARP packet
1085 * is on the interface we expect it to be on. This
1086 * avoids ARP chaos if an interface is connected to the
1090 /* XXX MRT use table 0 for arp checks */
1091 if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0)
1093 if (nh4.nh_ifp != ifp) {
1094 ARP_LOG(LOG_INFO, "proxy: ignoring request"
1095 " from %s via %s\n",
1096 inet_ntoa_r(isaddr, addrbuf),
1102 printf("arp: proxying for %s\n",
1103 inet_ntoa_r(itaddr, addrbuf));
1108 if (itaddr.s_addr == myaddr.s_addr &&
1109 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
1110 /* RFC 3927 link-local IPv4; always reply by broadcast. */
1111 #ifdef DEBUG_LINKLOCAL
1112 printf("arp: sending reply for link-local addr %s\n",
1113 inet_ntoa_r(itaddr, addrbuf));
1115 m->m_flags |= M_BCAST;
1116 m->m_flags &= ~M_MCAST;
1118 /* default behaviour; never reply by broadcast. */
1119 m->m_flags &= ~(M_BCAST|M_MCAST);
1121 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
1122 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
1123 ah->ar_op = htons(ARPOP_REPLY);
1124 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
1125 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
1126 m->m_pkthdr.len = m->m_len;
1127 m->m_pkthdr.rcvif = NULL;
1128 sa.sa_family = AF_ARP;
1131 /* Calculate link header for sending frame */
1132 bzero(&ro, sizeof(ro));
1133 linkhdrsize = sizeof(linkhdr);
1134 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize);
1137 * arp_fillheader() may fail due to lack of support inside encap request
1138 * routing. This is not necessary an error, AF_ARP can/should be handled
1141 if (error != 0 && error != EAFNOSUPPORT) {
1142 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
1143 if_name(ifp), error);
1147 ro.ro_prepend = linkhdr;
1148 ro.ro_plen = linkhdrsize;
1151 m_clrprotoflags(m); /* Avoid confusing lower layers. */
1152 (*ifp->if_output)(ifp, m, &sa, &ro);
1153 ARPSTAT_INC(txreplies);
1162 * Checks received arp data against existing @la.
1163 * Updates lle state/performs notification if necessary.
1166 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp,
1167 int bridged, struct llentry *la)
1170 struct mbuf *m_hold, *m_hold_next;
1171 uint8_t linkhdr[LLE_MAX_LINKHDR];
1174 char addrbuf[INET_ADDRSTRLEN];
1176 LLE_WLOCK_ASSERT(la);
1178 /* the following is not an error when doing bridging */
1179 if (!bridged && la->lle_tbl->llt_ifp != ifp) {
1180 if (log_arp_wrong_iface)
1181 ARP_LOG(LOG_WARNING, "%s is on %s "
1182 "but got reply from %*D on %s\n",
1183 inet_ntoa_r(isaddr, addrbuf),
1184 la->lle_tbl->llt_ifp->if_xname,
1185 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1190 if ((la->la_flags & LLE_VALID) &&
1191 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) {
1192 if (la->la_flags & LLE_STATIC) {
1194 if (log_arp_permanent_modify)
1196 "%*D attempts to modify "
1197 "permanent entry for %s on %s\n",
1199 (u_char *)ar_sha(ah), ":",
1200 inet_ntoa_r(isaddr, addrbuf),
1204 if (log_arp_movements) {
1205 ARP_LOG(LOG_INFO, "%s moved from %*D "
1207 inet_ntoa_r(isaddr, addrbuf),
1209 (u_char *)la->ll_addr, ":",
1210 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1215 /* Calculate full link prepend to use in lle */
1216 linkhdrsize = sizeof(linkhdr);
1217 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
1218 &linkhdrsize, &lladdr_off) != 0)
1221 /* Check if something has changed */
1222 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 ||
1223 (la->la_flags & LLE_VALID) == 0) {
1224 /* Try to perform LLE update */
1225 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
1229 /* Clear fast path feedback request if set */
1233 arp_mark_lle_reachable(la);
1236 * The packets are all freed within the call to the output
1239 * NB: The lock MUST be released before the call to the
1242 if (la->la_hold != NULL) {
1243 m_hold = la->la_hold;
1246 lltable_fill_sa_entry(la, &sa);
1248 for (; m_hold != NULL; m_hold = m_hold_next) {
1249 m_hold_next = m_hold->m_nextpkt;
1250 m_hold->m_nextpkt = NULL;
1251 /* Avoid confusing lower layers. */
1252 m_clrprotoflags(m_hold);
1253 (*ifp->if_output)(ifp, m_hold, &sa, NULL);
1260 arp_mark_lle_reachable(struct llentry *la)
1262 int canceled, wtime;
1264 LLE_WLOCK_ASSERT(la);
1266 la->ln_state = ARP_LLINFO_REACHABLE;
1267 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
1269 if (!(la->la_flags & LLE_STATIC)) {
1271 la->la_expire = time_uptime + V_arpt_keep;
1272 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit;
1274 wtime = V_arpt_keep;
1275 canceled = callout_reset(&la->lle_timer,
1276 hz * wtime, arptimer, la);
1281 la->la_preempt = V_arp_maxtries;
1285 * Add permanent link-layer record for given interface address.
1287 static __noinline void
1288 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst)
1290 struct llentry *lle, *lle_tmp;
1293 * Interface address LLE record is considered static
1294 * because kernel code relies on LLE_STATIC flag to check
1295 * if these entries can be rewriten by arp updates.
1297 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst);
1299 log(LOG_INFO, "arp_ifinit: cannot create arp "
1300 "entry for interface address\n");
1304 IF_AFDATA_WLOCK(ifp);
1306 /* Unlink any entry if exists */
1307 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1308 if (lle_tmp != NULL)
1309 lltable_unlink_entry(LLTABLE(ifp), lle_tmp);
1311 lltable_link_entry(LLTABLE(ifp), lle);
1312 IF_AFDATA_WUNLOCK(ifp);
1314 if (lle_tmp != NULL)
1315 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED);
1317 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED);
1319 if (lle_tmp != NULL)
1320 lltable_free_entry(LLTABLE(ifp), lle_tmp);
1324 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range
1328 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS)
1331 int rexmit_count = *(int *)arg1;
1333 error = sysctl_handle_int(oidp, &rexmit_count, 0, req);
1335 /* Enforce limits on any new value that may have been set. */
1336 if (!error && req->newptr) {
1337 /* A new value was set. */
1338 if (rexmit_count < 0) {
1340 } else if (rexmit_count > MAX_GARP_RETRANSMITS) {
1341 rexmit_count = MAX_GARP_RETRANSMITS;
1343 *(int *)arg1 = rexmit_count;
1350 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to
1351 * retransmit it again. A pending callout owns a reference to the ifa.
1354 garp_rexmit(void *arg)
1356 struct in_ifaddr *ia = arg;
1358 if (callout_pending(&ia->ia_garp_timer) ||
1359 !callout_active(&ia->ia_garp_timer)) {
1360 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1361 ifa_free(&ia->ia_ifa);
1365 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet);
1368 * Drop lock while the ARP request is generated.
1370 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1372 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr,
1373 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp));
1376 * Increment the count of retransmissions. If the count has reached the
1377 * maximum value, stop sending the GARP packets. Otherwise, schedule
1378 * the callout to retransmit another GARP packet.
1380 ++ia->ia_garp_count;
1381 if (ia->ia_garp_count >= garp_rexmit_count) {
1382 ifa_free(&ia->ia_ifa);
1385 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1386 rescheduled = callout_reset(&ia->ia_garp_timer,
1387 (1 << ia->ia_garp_count) * hz,
1389 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1391 ifa_free(&ia->ia_ifa);
1399 * Start the GARP retransmit timer.
1401 * A single GARP is always transmitted when an IPv4 address is added
1402 * to an interface and that is usually sufficient. However, in some
1403 * circumstances, such as when a shared address is passed between
1404 * cluster nodes, this single GARP may occasionally be dropped or
1405 * lost. This can lead to neighbors on the network link working with a
1406 * stale ARP cache and sending packets destined for that address to
1407 * the node that previously owned the address, which may not respond.
1409 * To avoid this situation, GARP retransmits can be enabled by setting
1410 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater
1411 * than zero. The setting represents the maximum number of
1412 * retransmissions. The interval between retransmissions is calculated
1413 * using an exponential backoff algorithm, doubling each time, so the
1414 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds).
1417 garp_timer_start(struct ifaddr *ifa)
1419 struct in_ifaddr *ia = (struct in_ifaddr *) ifa;
1421 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1422 ia->ia_garp_count = 0;
1423 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz,
1424 garp_rexmit, ia) == 0) {
1427 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1431 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
1433 const struct sockaddr_in *dst_in;
1434 const struct sockaddr *dst;
1436 if (ifa->ifa_carp != NULL)
1439 dst = ifa->ifa_addr;
1440 dst_in = (const struct sockaddr_in *)dst;
1442 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY)
1444 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)
1482 lltable_update_ifaddr(LLTABLE(ifp));
1484 if ((ifp->if_flags & IFF_UP) != 0)
1485 arp_handle_ifllchange(ifp);
1492 if (IS_DEFAULT_VNET(curvnet)) {
1493 netisr_register(&arp_nh);
1494 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event,
1495 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY);
1499 netisr_register_vnet(&arp_nh);
1502 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND,
1507 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH
1508 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5.
1511 vnet_arp_destroy(__unused void *arg)
1514 netisr_unregister_vnet(&arp_nh);
1516 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1517 vnet_arp_destroy, NULL);