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,
95 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
97 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp,
98 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
102 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20
104 VNET_DEFINE_STATIC(int, arp_maxtries) = 5;
105 VNET_DEFINE_STATIC(int, arp_proxyall) = 0;
106 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for
108 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/
109 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */
110 VNET_PCPUSTAT_SYSINIT(arpstat);
113 VNET_PCPUSTAT_SYSUNINIT(arpstat);
116 VNET_DEFINE_STATIC(int, arp_maxhold) = 1;
118 #define V_arpt_keep VNET(arpt_keep)
119 #define V_arpt_down VNET(arpt_down)
120 #define V_arpt_rexmit VNET(arpt_rexmit)
121 #define V_arp_maxtries VNET(arp_maxtries)
122 #define V_arp_proxyall VNET(arp_proxyall)
123 #define V_arp_maxhold VNET(arp_maxhold)
125 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW,
126 &VNET_NAME(arpt_keep), 0,
127 "ARP entry lifetime in seconds");
128 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW,
129 &VNET_NAME(arp_maxtries), 0,
130 "ARP resolution attempts before returning error");
131 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW,
132 &VNET_NAME(arp_proxyall), 0,
133 "Enable proxy ARP for all suitable requests");
134 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW,
135 &VNET_NAME(arpt_down), 0,
136 "Incomplete ARP entry lifetime in seconds");
137 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat,
138 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)");
139 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW,
140 &VNET_NAME(arp_maxhold), 0,
141 "Number of packets to hold per ARP entry");
142 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second,
143 CTLFLAG_RW, &arp_maxpps, 0,
144 "Maximum number of remotely triggered ARP messages that can be "
145 "logged per second");
148 * Due to the exponential backoff algorithm used for the interval between GARP
149 * retransmissions, the maximum number of retransmissions is limited for
150 * sanity. This limit corresponds to a maximum interval between retransmissions
151 * of 2^16 seconds ~= 18 hours.
153 * Making this limit more dynamic is more complicated than worthwhile,
154 * especially since sending out GARPs spaced days apart would be of little
155 * use. A maximum dynamic limit would look something like:
157 * const int max = fls(INT_MAX / hz) - 1;
159 #define MAX_GARP_RETRANSMITS 16
160 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS);
161 static int garp_rexmit_count = 0; /* GARP retransmission setting. */
163 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count,
164 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE,
165 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I",
166 "Number of times to retransmit GARP packets;"
167 " 0 to disable, maximum of 16");
169 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */
170 #define V_arp_log_level VNET(arp_log_level)
171 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW,
172 &VNET_NAME(arp_log_level), 0,
173 "Minimum log(9) level for recording rate limited arp log messages. "
174 "The higher will be log more (emerg=0, info=6 (default), debug=7).");
175 #define ARP_LOG(pri, ...) do { \
176 if ((pri) <= V_arp_log_level && \
177 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \
178 log((pri), "arp: " __VA_ARGS__); \
182 static void arpintr(struct mbuf *);
183 static void arptimer(void *);
185 static void in_arpinput(struct mbuf *);
188 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr,
189 struct ifnet *ifp, int bridged, struct llentry *la);
190 static void arp_mark_lle_reachable(struct llentry *la);
191 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp);
193 static eventhandler_tag iflladdr_tag;
195 static const struct netisr_handler arp_nh = {
197 .nh_handler = arpintr,
198 .nh_proto = NETISR_ARP,
199 .nh_policy = NETISR_POLICY_SOURCE,
203 * Timeout routine. Age arp_tab entries periodically.
208 struct llentry *lle = (struct llentry *)arg;
212 if (lle->la_flags & LLE_STATIC) {
216 if (callout_pending(&lle->lle_timer)) {
218 * Here we are a bit odd here in the treatment of
219 * active/pending. If the pending bit is set, it got
220 * rescheduled before I ran. The active
221 * bit we ignore, since if it was stopped
222 * in ll_tablefree() and was currently running
223 * it would have return 0 so the code would
224 * not have deleted it since the callout could
225 * not be stopped so we want to go through
226 * with the delete here now. If the callout
227 * was restarted, the pending bit will be back on and
228 * we just want to bail since the callout_reset would
229 * return 1 and our reference would have been removed
230 * by arpresolve() below.
235 ifp = lle->lle_tbl->llt_ifp;
236 CURVNET_SET(ifp->if_vnet);
238 switch (lle->ln_state) {
239 case ARP_LLINFO_REACHABLE:
242 * Expiration time is approaching.
243 * Let's try to refresh entry if it is still
246 * Set r_skip_req to get feedback from
247 * fast path. Change state and re-schedule
253 lle->ln_state = ARP_LLINFO_VERIFY;
254 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
258 case ARP_LLINFO_VERIFY:
260 r_skip_req = lle->r_skip_req;
263 if (r_skip_req == 0 && lle->la_preempt > 0) {
264 /* Entry was used, issue refresh request */
265 struct epoch_tracker et;
268 dst = lle->r_l3addr.addr4;
270 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
273 arprequest(ifp, NULL, &dst, NULL);
278 /* Nothing happened. Reschedule if not too late */
279 if (lle->la_expire > time_uptime) {
280 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
286 case ARP_LLINFO_INCOMPLETE:
287 case ARP_LLINFO_DELETED:
291 if ((lle->la_flags & LLE_DELETED) == 0) {
294 if (lle->la_flags & LLE_VALID)
295 evt = LLENTRY_EXPIRED;
297 evt = LLENTRY_TIMEDOUT;
298 EVENTHANDLER_INVOKE(lle_event, lle, evt);
301 callout_stop(&lle->lle_timer);
303 /* XXX: LOR avoidance. We still have ref on lle. */
308 /* Guard against race with other llentry_free(). */
309 if (lle->la_flags & LLE_LINKED) {
311 lltable_unlink_entry(lle->lle_tbl, lle);
313 IF_AFDATA_UNLOCK(ifp);
315 size_t pkts_dropped = llentry_free(lle);
317 ARPSTAT_ADD(dropped, pkts_dropped);
318 ARPSTAT_INC(timeouts);
324 * Stores link-layer header for @ifp in format suitable for if_output()
325 * into buffer @buf. Resulting header length is stored in @bufsize.
327 * Returns 0 on success.
330 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf,
333 struct if_encap_req ereq;
336 bzero(buf, *bufsize);
337 bzero(&ereq, sizeof(ereq));
339 ereq.bufsize = *bufsize;
340 ereq.rtype = IFENCAP_LL;
341 ereq.family = AF_ARP;
342 ereq.lladdr = ar_tha(ah);
343 ereq.hdata = (u_char *)ah;
345 ereq.flags = IFENCAP_FLAG_BROADCAST;
346 error = ifp->if_requestencap(ifp, &ereq);
348 *bufsize = ereq.bufsize;
355 * Broadcast an ARP request. Caller specifies:
356 * - arp header source ip address
357 * - arp header target ip address
358 * - arp header source ethernet address
361 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip,
362 const struct in_addr *tip, u_char *enaddr)
367 u_char *carpaddr = NULL;
368 uint8_t linkhdr[LLE_MAX_LINKHDR];
377 * The caller did not supply a source address, try to find
378 * a compatible one among those assigned to this interface.
382 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
383 if (ifa->ifa_addr->sa_family != AF_INET)
387 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
389 sip = &IA_SIN(ifa)->sin_addr;
392 sip = &IA_SIN(ifa)->sin_addr;
395 if (0 == ((sip->s_addr ^ tip->s_addr) &
396 IA_MASKSIN(ifa)->sin_addr.s_addr))
397 break; /* found it. */
400 printf("%s: cannot find matching address\n", __func__);
401 return (EADDRNOTAVAIL);
405 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
407 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
409 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
411 m->m_pkthdr.len = m->m_len;
412 M_ALIGN(m, m->m_len);
413 ah = mtod(m, struct arphdr *);
414 bzero((caddr_t)ah, m->m_len);
416 mac_netinet_arp_send(ifp, m);
418 ah->ar_pro = htons(ETHERTYPE_IP);
419 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
420 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
421 ah->ar_op = htons(ARPOP_REQUEST);
422 bcopy(enaddr, ar_sha(ah), ah->ar_hln);
423 bcopy(sip, ar_spa(ah), ah->ar_pln);
424 bcopy(tip, ar_tpa(ah), ah->ar_pln);
425 sa.sa_family = AF_ARP;
428 /* Calculate link header for sending frame */
429 bzero(&ro, sizeof(ro));
430 linkhdrsize = sizeof(linkhdr);
431 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize);
432 if (error != 0 && error != EAFNOSUPPORT) {
433 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
434 if_name(ifp), error);
438 ro.ro_prepend = linkhdr;
439 ro.ro_plen = linkhdrsize;
442 m->m_flags |= M_BCAST;
443 m_clrprotoflags(m); /* Avoid confusing lower layers. */
444 error = (*ifp->if_output)(ifp, m, &sa, &ro);
445 ARPSTAT_INC(txrequests);
447 ARPSTAT_INC(txerrors);
448 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n",
449 if_name(ifp), error);
455 arprequest(struct ifnet *ifp, const struct in_addr *sip,
456 const struct in_addr *tip, u_char *enaddr)
459 (void) arprequest_internal(ifp, sip, tip, enaddr);
463 * Resolve an IP address into an ethernet address - heavy version.
464 * Used internally by arpresolve().
465 * We have already checked that we can't use an existing lle without
466 * modification so we have to acquire an LLE_EXCLUSIVE lle lock.
468 * On success, desten and pflags are filled in and the function returns 0;
469 * If the packet must be held pending resolution, we return EWOULDBLOCK
470 * On other errors, we return the corresponding error code.
471 * Note that m_freem() handles NULL.
474 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m,
475 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
476 struct llentry **plle)
478 struct llentry *la = NULL, *la_tmp;
479 struct mbuf *curr = NULL;
480 struct mbuf *next = NULL;
492 if ((flags & LLE_CREATE) == 0)
493 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
494 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
495 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
497 char addrbuf[INET_ADDRSTRLEN];
500 "arpresolve: can't allocate llinfo for %s on %s\n",
501 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf),
507 IF_AFDATA_WLOCK(ifp);
509 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
510 /* Prefer ANY existing lle over newly-created one */
512 lltable_link_entry(LLTABLE(ifp), la);
513 IF_AFDATA_WUNLOCK(ifp);
514 if (la_tmp != NULL) {
515 lltable_free_entry(LLTABLE(ifp), la);
524 if ((la->la_flags & LLE_VALID) &&
525 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
526 if (flags & LLE_ADDRONLY) {
527 lladdr = la->ll_addr;
528 ll_len = ifp->if_addrlen;
530 lladdr = la->r_linkdata;
531 ll_len = la->r_hdrlen;
533 bcopy(lladdr, desten, ll_len);
535 /* Notify LLE code that the entry was used by datapath */
536 llentry_mark_used(la);
538 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR);
547 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
549 * There is an arptab entry, but no ethernet address
550 * response yet. Add the mbuf to the list, dropping
551 * the oldest packet if we have exceeded the system
555 if (la->la_numheld >= V_arp_maxhold) {
556 if (la->la_hold != NULL) {
557 next = la->la_hold->m_nextpkt;
558 m_freem(la->la_hold);
561 ARPSTAT_INC(dropped);
564 if (la->la_hold != NULL) {
566 while (curr->m_nextpkt != NULL)
567 curr = curr->m_nextpkt;
574 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
575 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
576 * if we have already sent arp_maxtries ARP requests. Retransmit the
577 * ARP request, but not faster than one request per second.
579 if (la->la_asked < V_arp_maxtries)
580 error = EWOULDBLOCK; /* First request. */
582 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN;
588 la->la_expire = time_uptime;
589 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down,
595 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL);
597 * Only overwrite 'error' in case of error; in case of success
598 * the proper return value was already set above.
610 * Lookups link header based on an IP address.
612 * ifp is the interface we use
613 * is_gw != 0 if @dst represents gateway to some destination
614 * m is the mbuf. May be NULL if we don't have a packet.
615 * dst is the next hop,
616 * desten is the storage to put LL header.
617 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR
619 * On success, full/partial link header and flags are filled in and
620 * the function returns 0.
621 * If the packet must be held pending resolution, we return EWOULDBLOCK
622 * On other errors, we return the corresponding error code.
623 * Note that m_freem() handles NULL.
626 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
627 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
628 struct llentry **plle)
630 struct llentry *la = NULL;
640 if (m->m_flags & M_BCAST) {
643 ifp->if_broadcastaddr, ifp->if_addrlen);
646 if (m->m_flags & M_MCAST) {
648 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
653 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst);
654 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) {
655 /* Entry found, let's copy lle info */
656 bcopy(la->r_linkdata, desten, la->r_hdrlen);
658 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR);
659 /* Notify the LLE handling code that the entry was used. */
660 llentry_mark_used(la);
671 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst,
672 desten, pflags, plle));
676 * Common length and type checks are done here,
677 * then the protocol-specific routine is called.
680 arpintr(struct mbuf *m)
687 ifp = m->m_pkthdr.rcvif;
689 if (m->m_len < sizeof(struct arphdr) &&
690 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
691 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n",
695 ar = mtod(m, struct arphdr *);
697 /* Check if length is sufficient */
698 if (m->m_len < arphdr_len(ar)) {
699 m = m_pullup(m, arphdr_len(ar));
701 ARP_LOG(LOG_NOTICE, "short packet received on %s\n",
705 ar = mtod(m, struct arphdr *);
710 switch (ntohs(ar->ar_hrd)) {
712 hlen = ETHER_ADDR_LEN; /* RFC 826 */
715 case ARPHRD_INFINIBAND:
716 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */
717 layer = "infiniband";
719 case ARPHRD_IEEE1394:
720 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */
724 * Restrict too long hardware addresses.
725 * Currently we are capable of handling 20-byte
726 * addresses ( sizeof(lle->ll_addr) )
728 if (ar->ar_hln >= 20)
733 "packet with unknown hardware format 0x%02d received on "
734 "%s\n", ntohs(ar->ar_hrd), if_name(ifp));
739 if (hlen != 0 && hlen != ar->ar_hln) {
741 "packet with invalid %s address length %d received on %s\n",
742 layer, ar->ar_hln, if_name(ifp));
747 ARPSTAT_INC(received);
748 switch (ntohs(ar->ar_pro)) {
760 * ARP for Internet protocols on 10 Mb/s Ethernet.
761 * Algorithm is that given in RFC 826.
762 * In addition, a sanity check is performed on the sender
763 * protocol address, to catch impersonators.
764 * We no longer handle negotiations for use of trailer protocol:
765 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
766 * along with IP replies if we wanted trailers sent to us,
767 * and also sent them in response to IP replies.
768 * This allowed either end to announce the desire to receive
770 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
771 * but formerly didn't normally send requests.
773 static int log_arp_wrong_iface = 1;
774 static int log_arp_movements = 1;
775 static int log_arp_permanent_modify = 1;
776 static int allow_multicast = 0;
778 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
779 &log_arp_wrong_iface, 0,
780 "log arp packets arriving on the wrong interface");
781 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
782 &log_arp_movements, 0,
783 "log arp replies from MACs different than the one in the cache");
784 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
785 &log_arp_permanent_modify, 0,
786 "log arp replies from MACs different than the one in the permanent arp entry");
787 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
788 &allow_multicast, 0, "accept multicast addresses");
791 in_arpinput(struct mbuf *m)
793 struct rm_priotracker in_ifa_tracker;
795 struct ifnet *ifp = m->m_pkthdr.rcvif;
796 struct llentry *la = NULL, *la_tmp;
798 struct in_ifaddr *ia;
800 struct in_addr isaddr, itaddr, myaddr;
801 u_int8_t *enaddr = NULL;
803 int bridged = 0, is_bridge = 0;
805 struct sockaddr_in sin;
806 struct sockaddr *dst;
807 struct nhop4_basic nh4;
808 uint8_t linkhdr[LLE_MAX_LINKHDR];
813 char addrbuf[INET_ADDRSTRLEN];
817 sin.sin_len = sizeof(struct sockaddr_in);
818 sin.sin_family = AF_INET;
819 sin.sin_addr.s_addr = 0;
823 if (ifp->if_type == IFT_BRIDGE)
827 * We already have checked that mbuf contains enough contiguous data
828 * to hold entire arp message according to the arp header.
830 ah = mtod(m, struct arphdr *);
833 * ARP is only for IPv4 so we can reject packets with
834 * a protocol length not equal to an IPv4 address.
836 if (ah->ar_pln != sizeof(struct in_addr)) {
837 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
838 sizeof(struct in_addr));
842 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
843 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
844 ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
848 op = ntohs(ah->ar_op);
849 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
850 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
852 if (op == ARPOP_REPLY)
853 ARPSTAT_INC(rxreplies);
856 * For a bridge, we want to check the address irrespective
857 * of the receive interface. (This will change slightly
858 * when we have clusters of interfaces).
860 IN_IFADDR_RLOCK(&in_ifa_tracker);
861 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
862 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
863 ia->ia_ifp == ifp) &&
864 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
865 (ia->ia_ifa.ifa_carp == NULL ||
866 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
867 ifa_ref(&ia->ia_ifa);
868 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
872 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
873 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
874 ia->ia_ifp == ifp) &&
875 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
876 ifa_ref(&ia->ia_ifa);
877 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
881 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
882 (ia->ia_ifp->if_bridge == ifp->if_softc && \
883 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
884 addr == ia->ia_addr.sin_addr.s_addr)
886 * Check the case when bridge shares its MAC address with
887 * some of its children, so packets are claimed by bridge
888 * itself (bridge_input() does it first), but they are really
889 * meant to be destined to the bridge member.
892 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
893 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
894 ifa_ref(&ia->ia_ifa);
896 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
901 #undef BDG_MEMBER_MATCHES_ARP
902 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
905 * No match, use the first inet address on the receive interface
906 * as a dummy address for the rest of the function.
908 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
909 if (ifa->ifa_addr->sa_family == AF_INET &&
910 (ifa->ifa_carp == NULL ||
911 (*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;
972 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
974 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
975 else if (itaddr.s_addr == myaddr.s_addr) {
977 * Request/reply to our address, but no lle exists yet.
978 * Calculate full link prepend to use in lle.
980 linkhdrsize = sizeof(linkhdr);
981 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
982 &linkhdrsize, &lladdr_off) != 0)
985 /* Allocate new entry */
986 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
990 * lle creation may fail if source address belongs
991 * to non-directly connected subnet. However, we
992 * will try to answer the request instead of dropping
997 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
1000 IF_AFDATA_WLOCK(ifp);
1002 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1005 * Check if lle still does not exists.
1006 * If it does, that means that we either
1007 * 1) have configured it explicitly, via
1008 * 1a) 'arp -s' static entry or
1009 * 1b) interface address static record
1011 * 2) it was the result of sending first packet to-host
1013 * 3) it was another arp reply packet we handled in
1016 * In all cases except 3) we definitely need to prefer
1017 * existing lle. For the sake of simplicity, prefer any
1018 * existing lle over newly-create one.
1021 lltable_link_entry(LLTABLE(ifp), la);
1022 IF_AFDATA_WUNLOCK(ifp);
1024 if (la_tmp == NULL) {
1025 arp_mark_lle_reachable(la);
1028 /* Free newly-create entry and handle packet */
1029 lltable_free_entry(LLTABLE(ifp), la);
1032 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
1033 /* arp_check_update_lle() returns @la unlocked */
1038 if (op != ARPOP_REQUEST)
1040 ARPSTAT_INC(rxrequests);
1042 if (itaddr.s_addr == myaddr.s_addr) {
1043 /* Shortcut.. the receiving interface is the target. */
1044 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1045 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1048 * Destination address is not ours. Check if
1049 * proxyarp entry exists or proxyarp is turned on globally.
1051 struct llentry *lle;
1053 sin.sin_addr = itaddr;
1054 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 if (fib4_lookup_nh_basic(ifp->if_fib, itaddr, 0, 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 if (fib4_lookup_nh_basic(ifp->if_fib, isaddr, 0, 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 struct epoch_tracker et;
1434 const struct sockaddr_in *dst_in;
1435 const struct sockaddr *dst;
1437 if (ifa->ifa_carp != NULL)
1440 dst = ifa->ifa_addr;
1441 dst_in = (const struct sockaddr_in *)dst;
1443 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY)
1445 NET_EPOCH_ENTER(et);
1446 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp));
1448 if (garp_rexmit_count > 0) {
1449 garp_timer_start(ifa);
1452 arp_add_ifa_lle(ifp, dst);
1456 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr)
1459 if (ntohl(addr.s_addr) != INADDR_ANY)
1460 arprequest(ifp, &addr, &addr, enaddr);
1464 * Sends gratuitous ARPs for each ifaddr to notify other
1465 * nodes about the address change.
1467 static __noinline void
1468 arp_handle_ifllchange(struct ifnet *ifp)
1472 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
1473 if (ifa->ifa_addr->sa_family == AF_INET)
1474 arp_ifinit(ifp, ifa);
1479 * A handler for interface link layer address change event.
1482 arp_iflladdr(void *arg __unused, struct ifnet *ifp)
1485 lltable_update_ifaddr(LLTABLE(ifp));
1487 if ((ifp->if_flags & IFF_UP) != 0)
1488 arp_handle_ifllchange(ifp);
1495 if (IS_DEFAULT_VNET(curvnet)) {
1496 netisr_register(&arp_nh);
1497 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event,
1498 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY);
1502 netisr_register_vnet(&arp_nh);
1505 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND,
1510 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH
1511 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5.
1514 vnet_arp_destroy(__unused void *arg)
1517 netisr_unregister_vnet(&arp_nh);
1519 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1520 vnet_arp_destroy, NULL);