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/kernel.h>
48 #include <sys/queue.h>
49 #include <sys/sysctl.h>
50 #include <sys/systm.h>
52 #include <sys/malloc.h>
54 #include <sys/rmlock.h>
55 #include <sys/socket.h>
56 #include <sys/syslog.h>
59 #include <net/if_var.h>
60 #include <net/if_dl.h>
61 #include <net/if_types.h>
62 #include <net/netisr.h>
63 #include <net/ethernet.h>
64 #include <net/route.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, CTLFLAG_RW, 0, "");
94 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, "");
97 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20
99 VNET_DEFINE_STATIC(int, arp_maxtries) = 5;
100 VNET_DEFINE_STATIC(int, arp_proxyall) = 0;
101 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for
103 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/
104 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */
105 VNET_PCPUSTAT_SYSINIT(arpstat);
108 VNET_PCPUSTAT_SYSUNINIT(arpstat);
111 VNET_DEFINE_STATIC(int, arp_maxhold) = 1;
113 #define V_arpt_keep VNET(arpt_keep)
114 #define V_arpt_down VNET(arpt_down)
115 #define V_arpt_rexmit VNET(arpt_rexmit)
116 #define V_arp_maxtries VNET(arp_maxtries)
117 #define V_arp_proxyall VNET(arp_proxyall)
118 #define V_arp_maxhold VNET(arp_maxhold)
120 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW,
121 &VNET_NAME(arpt_keep), 0,
122 "ARP entry lifetime in seconds");
123 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW,
124 &VNET_NAME(arp_maxtries), 0,
125 "ARP resolution attempts before returning error");
126 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW,
127 &VNET_NAME(arp_proxyall), 0,
128 "Enable proxy ARP for all suitable requests");
129 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW,
130 &VNET_NAME(arpt_down), 0,
131 "Incomplete ARP entry lifetime in seconds");
132 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat,
133 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)");
134 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW,
135 &VNET_NAME(arp_maxhold), 0,
136 "Number of packets to hold per ARP entry");
137 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second,
138 CTLFLAG_RW, &arp_maxpps, 0,
139 "Maximum number of remotely triggered ARP messages that can be "
140 "logged per second");
143 * Due to the exponential backoff algorithm used for the interval between GARP
144 * retransmissions, the maximum number of retransmissions is limited for
145 * sanity. This limit corresponds to a maximum interval between retransmissions
146 * of 2^16 seconds ~= 18 hours.
148 * Making this limit more dynamic is more complicated than worthwhile,
149 * especially since sending out GARPs spaced days apart would be of little
150 * use. A maximum dynamic limit would look something like:
152 * const int max = fls(INT_MAX / hz) - 1;
154 #define MAX_GARP_RETRANSMITS 16
155 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS);
156 static int garp_rexmit_count = 0; /* GARP retransmission setting. */
158 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count,
159 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE,
160 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I",
161 "Number of times to retransmit GARP packets;"
162 " 0 to disable, maximum of 16");
164 #define ARP_LOG(pri, ...) do { \
165 if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \
166 log((pri), "arp: " __VA_ARGS__); \
170 static void arpintr(struct mbuf *);
171 static void arptimer(void *);
173 static void in_arpinput(struct mbuf *);
176 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr,
177 struct ifnet *ifp, int bridged, struct llentry *la);
178 static void arp_mark_lle_reachable(struct llentry *la);
179 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp);
181 static eventhandler_tag iflladdr_tag;
183 static const struct netisr_handler arp_nh = {
185 .nh_handler = arpintr,
186 .nh_proto = NETISR_ARP,
187 .nh_policy = NETISR_POLICY_SOURCE,
191 * Timeout routine. Age arp_tab entries periodically.
196 struct llentry *lle = (struct llentry *)arg;
200 if (lle->la_flags & LLE_STATIC) {
204 if (callout_pending(&lle->lle_timer)) {
206 * Here we are a bit odd here in the treatment of
207 * active/pending. If the pending bit is set, it got
208 * rescheduled before I ran. The active
209 * bit we ignore, since if it was stopped
210 * in ll_tablefree() and was currently running
211 * it would have return 0 so the code would
212 * not have deleted it since the callout could
213 * not be stopped so we want to go through
214 * with the delete here now. If the callout
215 * was restarted, the pending bit will be back on and
216 * we just want to bail since the callout_reset would
217 * return 1 and our reference would have been removed
218 * by arpresolve() below.
223 ifp = lle->lle_tbl->llt_ifp;
224 CURVNET_SET(ifp->if_vnet);
226 switch (lle->ln_state) {
227 case ARP_LLINFO_REACHABLE:
230 * Expiration time is approaching.
231 * Let's try to refresh entry if it is still
234 * Set r_skip_req to get feedback from
235 * fast path. Change state and re-schedule
241 lle->ln_state = ARP_LLINFO_VERIFY;
242 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
246 case ARP_LLINFO_VERIFY:
248 r_skip_req = lle->r_skip_req;
251 if (r_skip_req == 0 && lle->la_preempt > 0) {
252 /* Entry was used, issue refresh request */
254 dst = lle->r_l3addr.addr4;
256 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
258 arprequest(ifp, NULL, &dst, NULL);
262 /* Nothing happened. Reschedule if not too late */
263 if (lle->la_expire > time_uptime) {
264 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
270 case ARP_LLINFO_INCOMPLETE:
271 case ARP_LLINFO_DELETED:
275 if ((lle->la_flags & LLE_DELETED) == 0) {
278 if (lle->la_flags & LLE_VALID)
279 evt = LLENTRY_EXPIRED;
281 evt = LLENTRY_TIMEDOUT;
282 EVENTHANDLER_INVOKE(lle_event, lle, evt);
285 callout_stop(&lle->lle_timer);
287 /* XXX: LOR avoidance. We still have ref on lle. */
292 /* Guard against race with other llentry_free(). */
293 if (lle->la_flags & LLE_LINKED) {
295 lltable_unlink_entry(lle->lle_tbl, lle);
297 IF_AFDATA_UNLOCK(ifp);
299 size_t pkts_dropped = llentry_free(lle);
301 ARPSTAT_ADD(dropped, pkts_dropped);
302 ARPSTAT_INC(timeouts);
308 * Stores link-layer header for @ifp in format suitable for if_output()
309 * into buffer @buf. Resulting header length is stored in @bufsize.
311 * Returns 0 on success.
314 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf,
317 struct if_encap_req ereq;
320 bzero(buf, *bufsize);
321 bzero(&ereq, sizeof(ereq));
323 ereq.bufsize = *bufsize;
324 ereq.rtype = IFENCAP_LL;
325 ereq.family = AF_ARP;
326 ereq.lladdr = ar_tha(ah);
327 ereq.hdata = (u_char *)ah;
329 ereq.flags = IFENCAP_FLAG_BROADCAST;
330 error = ifp->if_requestencap(ifp, &ereq);
332 *bufsize = ereq.bufsize;
339 * Broadcast an ARP request. Caller specifies:
340 * - arp header source ip address
341 * - arp header target ip address
342 * - arp header source ethernet address
345 arprequest(struct ifnet *ifp, const struct in_addr *sip,
346 const struct in_addr *tip, u_char *enaddr)
351 u_char *carpaddr = NULL;
352 uint8_t linkhdr[LLE_MAX_LINKHDR];
359 * The caller did not supply a source address, try to find
360 * a compatible one among those assigned to this interface.
362 struct epoch_tracker et;
366 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
367 if (ifa->ifa_addr->sa_family != AF_INET)
371 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
373 sip = &IA_SIN(ifa)->sin_addr;
376 sip = &IA_SIN(ifa)->sin_addr;
379 if (0 == ((sip->s_addr ^ tip->s_addr) &
380 IA_MASKSIN(ifa)->sin_addr.s_addr))
381 break; /* found it. */
385 printf("%s: cannot find matching address\n", __func__);
390 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
392 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
394 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
396 m->m_pkthdr.len = m->m_len;
397 M_ALIGN(m, m->m_len);
398 ah = mtod(m, struct arphdr *);
399 bzero((caddr_t)ah, m->m_len);
401 mac_netinet_arp_send(ifp, m);
403 ah->ar_pro = htons(ETHERTYPE_IP);
404 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
405 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
406 ah->ar_op = htons(ARPOP_REQUEST);
407 bcopy(enaddr, ar_sha(ah), ah->ar_hln);
408 bcopy(sip, ar_spa(ah), ah->ar_pln);
409 bcopy(tip, ar_tpa(ah), ah->ar_pln);
410 sa.sa_family = AF_ARP;
413 /* Calculate link header for sending frame */
414 bzero(&ro, sizeof(ro));
415 linkhdrsize = sizeof(linkhdr);
416 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize);
417 if (error != 0 && error != EAFNOSUPPORT) {
418 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
419 if_name(ifp), error);
423 ro.ro_prepend = linkhdr;
424 ro.ro_plen = linkhdrsize;
427 m->m_flags |= M_BCAST;
428 m_clrprotoflags(m); /* Avoid confusing lower layers. */
429 (*ifp->if_output)(ifp, m, &sa, &ro);
430 ARPSTAT_INC(txrequests);
435 * Resolve an IP address into an ethernet address - heavy version.
436 * Used internally by arpresolve().
437 * We have already checked that we can't use an existing lle without
438 * modification so we have to acquire an LLE_EXCLUSIVE lle lock.
440 * On success, desten and pflags are filled in and the function returns 0;
441 * If the packet must be held pending resolution, we return EWOULDBLOCK
442 * On other errors, we return the corresponding error code.
443 * Note that m_freem() handles NULL.
446 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m,
447 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
448 struct llentry **plle)
450 struct llentry *la = NULL, *la_tmp;
451 struct mbuf *curr = NULL;
452 struct mbuf *next = NULL;
462 if ((flags & LLE_CREATE) == 0) {
463 struct epoch_tracker et;
466 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
469 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
470 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
472 char addrbuf[INET_ADDRSTRLEN];
475 "arpresolve: can't allocate llinfo for %s on %s\n",
476 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf),
482 IF_AFDATA_WLOCK(ifp);
484 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
485 /* Prefer ANY existing lle over newly-created one */
487 lltable_link_entry(LLTABLE(ifp), la);
488 IF_AFDATA_WUNLOCK(ifp);
489 if (la_tmp != NULL) {
490 lltable_free_entry(LLTABLE(ifp), la);
499 if ((la->la_flags & LLE_VALID) &&
500 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
501 if (flags & LLE_ADDRONLY) {
502 lladdr = la->ll_addr;
503 ll_len = ifp->if_addrlen;
505 lladdr = la->r_linkdata;
506 ll_len = la->r_hdrlen;
508 bcopy(lladdr, desten, ll_len);
510 /* Notify LLE code that the entry was used by datapath */
511 llentry_mark_used(la);
513 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR);
522 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
524 * There is an arptab entry, but no ethernet address
525 * response yet. Add the mbuf to the list, dropping
526 * the oldest packet if we have exceeded the system
530 if (la->la_numheld >= V_arp_maxhold) {
531 if (la->la_hold != NULL) {
532 next = la->la_hold->m_nextpkt;
533 m_freem(la->la_hold);
536 ARPSTAT_INC(dropped);
539 if (la->la_hold != NULL) {
541 while (curr->m_nextpkt != NULL)
542 curr = curr->m_nextpkt;
549 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
550 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
551 * if we have already sent arp_maxtries ARP requests. Retransmit the
552 * ARP request, but not faster than one request per second.
554 if (la->la_asked < V_arp_maxtries)
555 error = EWOULDBLOCK; /* First request. */
557 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN;
563 la->la_expire = time_uptime;
564 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down,
570 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
579 * Lookups link header based on an IP address.
581 * ifp is the interface we use
582 * is_gw != 0 if @dst represents gateway to some destination
583 * m is the mbuf. May be NULL if we don't have a packet.
584 * dst is the next hop,
585 * desten is the storage to put LL header.
586 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR
588 * On success, full/partial link header and flags are filled in and
589 * the function returns 0.
590 * If the packet must be held pending resolution, we return EWOULDBLOCK
591 * On other errors, we return the corresponding error code.
592 * Note that m_freem() handles NULL.
595 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
596 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
597 struct llentry **plle)
599 struct epoch_tracker et;
600 struct llentry *la = NULL;
608 if (m->m_flags & M_BCAST) {
611 ifp->if_broadcastaddr, ifp->if_addrlen);
614 if (m->m_flags & M_MCAST) {
616 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
622 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst);
623 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) {
624 /* Entry found, let's copy lle info */
625 bcopy(la->r_linkdata, desten, la->r_hdrlen);
627 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR);
628 /* Notify the LLE handling code that the entry was used. */
629 llentry_mark_used(la);
642 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst,
643 desten, pflags, plle));
647 * Common length and type checks are done here,
648 * then the protocol-specific routine is called.
651 arpintr(struct mbuf *m)
658 ifp = m->m_pkthdr.rcvif;
660 if (m->m_len < sizeof(struct arphdr) &&
661 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
662 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n",
666 ar = mtod(m, struct arphdr *);
668 /* Check if length is sufficient */
669 if (m->m_len < arphdr_len(ar)) {
670 m = m_pullup(m, arphdr_len(ar));
672 ARP_LOG(LOG_NOTICE, "short packet received on %s\n",
676 ar = mtod(m, struct arphdr *);
681 switch (ntohs(ar->ar_hrd)) {
683 hlen = ETHER_ADDR_LEN; /* RFC 826 */
686 case ARPHRD_INFINIBAND:
687 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */
688 layer = "infiniband";
690 case ARPHRD_IEEE1394:
691 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */
695 * Restrict too long hardware addresses.
696 * Currently we are capable of handling 20-byte
697 * addresses ( sizeof(lle->ll_addr) )
699 if (ar->ar_hln >= 20)
704 "packet with unknown hardware format 0x%02d received on "
705 "%s\n", ntohs(ar->ar_hrd), if_name(ifp));
710 if (hlen != 0 && hlen != ar->ar_hln) {
712 "packet with invalid %s address length %d received on %s\n",
713 layer, ar->ar_hln, if_name(ifp));
718 ARPSTAT_INC(received);
719 switch (ntohs(ar->ar_pro)) {
731 * ARP for Internet protocols on 10 Mb/s Ethernet.
732 * Algorithm is that given in RFC 826.
733 * In addition, a sanity check is performed on the sender
734 * protocol address, to catch impersonators.
735 * We no longer handle negotiations for use of trailer protocol:
736 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
737 * along with IP replies if we wanted trailers sent to us,
738 * and also sent them in response to IP replies.
739 * This allowed either end to announce the desire to receive
741 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
742 * but formerly didn't normally send requests.
744 static int log_arp_wrong_iface = 1;
745 static int log_arp_movements = 1;
746 static int log_arp_permanent_modify = 1;
747 static int allow_multicast = 0;
749 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
750 &log_arp_wrong_iface, 0,
751 "log arp packets arriving on the wrong interface");
752 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
753 &log_arp_movements, 0,
754 "log arp replies from MACs different than the one in the cache");
755 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
756 &log_arp_permanent_modify, 0,
757 "log arp replies from MACs different than the one in the permanent arp entry");
758 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
759 &allow_multicast, 0, "accept multicast addresses");
762 in_arpinput(struct mbuf *m)
764 struct rm_priotracker in_ifa_tracker;
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 nhop4_basic nh4;
779 uint8_t linkhdr[LLE_MAX_LINKHDR];
784 char addrbuf[INET_ADDRSTRLEN];
785 struct epoch_tracker et;
787 sin.sin_len = sizeof(struct sockaddr_in);
788 sin.sin_family = AF_INET;
789 sin.sin_addr.s_addr = 0;
793 if (ifp->if_type == IFT_BRIDGE)
797 * We already have checked that mbuf contains enough contiguous data
798 * to hold entire arp message according to the arp header.
800 ah = mtod(m, struct arphdr *);
803 * ARP is only for IPv4 so we can reject packets with
804 * a protocol length not equal to an IPv4 address.
806 if (ah->ar_pln != sizeof(struct in_addr)) {
807 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
808 sizeof(struct in_addr));
812 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
813 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
814 ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
818 op = ntohs(ah->ar_op);
819 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
820 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
822 if (op == ARPOP_REPLY)
823 ARPSTAT_INC(rxreplies);
826 * For a bridge, we want to check the address irrespective
827 * of the receive interface. (This will change slightly
828 * when we have clusters of interfaces).
830 IN_IFADDR_RLOCK(&in_ifa_tracker);
831 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);
838 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
842 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
843 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
844 ia->ia_ifp == ifp) &&
845 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
846 ifa_ref(&ia->ia_ifa);
847 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
851 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
852 (ia->ia_ifp->if_bridge == ifp->if_softc && \
853 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
854 addr == ia->ia_addr.sin_addr.s_addr)
856 * Check the case when bridge shares its MAC address with
857 * some of its children, so packets are claimed by bridge
858 * itself (bridge_input() does it first), but they are really
859 * meant to be destined to the bridge member.
862 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
863 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
864 ifa_ref(&ia->ia_ifa);
866 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
871 #undef BDG_MEMBER_MATCHES_ARP
872 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
875 * No match, use the first inet address on the receive interface
876 * as a dummy address for the rest of the function.
879 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
880 if (ifa->ifa_addr->sa_family == AF_INET &&
881 (ifa->ifa_carp == NULL ||
882 (*carp_iamatch_p)(ifa, &enaddr))) {
891 * If bridging, fall back to using any inet address.
893 IN_IFADDR_RLOCK(&in_ifa_tracker);
894 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
895 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
898 ifa_ref(&ia->ia_ifa);
899 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
902 enaddr = (u_int8_t *)IF_LLADDR(ifp);
903 carped = (ia->ia_ifa.ifa_carp != NULL);
904 myaddr = ia->ia_addr.sin_addr;
905 ifa_free(&ia->ia_ifa);
906 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
907 goto drop; /* it's from me, ignore it. */
908 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
909 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
910 "%s!\n", inet_ntoa_r(isaddr, addrbuf));
914 if (ifp->if_addrlen != ah->ar_hln) {
915 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
916 "i/f %d (ignored)\n", ifp->if_addrlen,
917 (u_char *) ar_sha(ah), ":", ah->ar_hln,
923 * Warn if another host is using the same IP address, but only if the
924 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
925 * case we suppress the warning to avoid false positive complaints of
926 * potential misconfiguration.
928 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
929 myaddr.s_addr != 0) {
930 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
931 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
932 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname);
937 if (ifp->if_flags & IFF_STATICARP)
940 bzero(&sin, sizeof(sin));
941 sin.sin_len = sizeof(struct sockaddr_in);
942 sin.sin_family = AF_INET;
943 sin.sin_addr = isaddr;
944 dst = (struct sockaddr *)&sin;
946 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
949 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
950 else if (itaddr.s_addr == myaddr.s_addr) {
952 * Request/reply to our address, but no lle exists yet.
953 * Calculate full link prepend to use in lle.
955 linkhdrsize = sizeof(linkhdr);
956 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
957 &linkhdrsize, &lladdr_off) != 0)
960 /* Allocate new entry */
961 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
965 * lle creation may fail if source address belongs
966 * to non-directly connected subnet. However, we
967 * will try to answer the request instead of dropping
972 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
975 IF_AFDATA_WLOCK(ifp);
977 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
980 * Check if lle still does not exists.
981 * If it does, that means that we either
982 * 1) have configured it explicitly, via
983 * 1a) 'arp -s' static entry or
984 * 1b) interface address static record
986 * 2) it was the result of sending first packet to-host
988 * 3) it was another arp reply packet we handled in
991 * In all cases except 3) we definitely need to prefer
992 * existing lle. For the sake of simplicity, prefer any
993 * existing lle over newly-create one.
996 lltable_link_entry(LLTABLE(ifp), la);
997 IF_AFDATA_WUNLOCK(ifp);
999 if (la_tmp == NULL) {
1000 arp_mark_lle_reachable(la);
1003 /* Free newly-create entry and handle packet */
1004 lltable_free_entry(LLTABLE(ifp), la);
1007 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
1008 /* arp_check_update_lle() returns @la unlocked */
1013 if (op != ARPOP_REQUEST)
1015 ARPSTAT_INC(rxrequests);
1017 if (itaddr.s_addr == myaddr.s_addr) {
1018 /* Shortcut.. the receiving interface is the target. */
1019 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1020 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1022 struct llentry *lle = NULL;
1024 sin.sin_addr = itaddr;
1025 NET_EPOCH_ENTER(et);
1026 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
1029 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
1030 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1031 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln);
1038 if (!V_arp_proxyall)
1041 /* XXX MRT use table 0 for arp reply */
1042 if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0)
1046 * Don't send proxies for nodes on the same interface
1047 * as this one came out of, or we'll get into a fight
1048 * over who claims what Ether address.
1050 if (nh4.nh_ifp == ifp)
1053 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1054 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1057 * Also check that the node which sent the ARP packet
1058 * is on the interface we expect it to be on. This
1059 * avoids ARP chaos if an interface is connected to the
1063 /* XXX MRT use table 0 for arp checks */
1064 if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0)
1066 if (nh4.nh_ifp != ifp) {
1067 ARP_LOG(LOG_INFO, "proxy: ignoring request"
1068 " from %s via %s\n",
1069 inet_ntoa_r(isaddr, addrbuf),
1075 printf("arp: proxying for %s\n",
1076 inet_ntoa_r(itaddr, addrbuf));
1081 if (itaddr.s_addr == myaddr.s_addr &&
1082 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
1083 /* RFC 3927 link-local IPv4; always reply by broadcast. */
1084 #ifdef DEBUG_LINKLOCAL
1085 printf("arp: sending reply for link-local addr %s\n",
1086 inet_ntoa_r(itaddr, addrbuf));
1088 m->m_flags |= M_BCAST;
1089 m->m_flags &= ~M_MCAST;
1091 /* default behaviour; never reply by broadcast. */
1092 m->m_flags &= ~(M_BCAST|M_MCAST);
1094 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
1095 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
1096 ah->ar_op = htons(ARPOP_REPLY);
1097 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
1098 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
1099 m->m_pkthdr.len = m->m_len;
1100 m->m_pkthdr.rcvif = NULL;
1101 sa.sa_family = AF_ARP;
1104 /* Calculate link header for sending frame */
1105 bzero(&ro, sizeof(ro));
1106 linkhdrsize = sizeof(linkhdr);
1107 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize);
1110 * arp_fillheader() may fail due to lack of support inside encap request
1111 * routing. This is not necessary an error, AF_ARP can/should be handled
1114 if (error != 0 && error != EAFNOSUPPORT) {
1115 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
1116 if_name(ifp), error);
1120 ro.ro_prepend = linkhdr;
1121 ro.ro_plen = linkhdrsize;
1124 m_clrprotoflags(m); /* Avoid confusing lower layers. */
1125 (*ifp->if_output)(ifp, m, &sa, &ro);
1126 ARPSTAT_INC(txreplies);
1135 * Checks received arp data against existing @la.
1136 * Updates lle state/performs notification if necessary.
1139 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp,
1140 int bridged, struct llentry *la)
1143 struct mbuf *m_hold, *m_hold_next;
1144 uint8_t linkhdr[LLE_MAX_LINKHDR];
1147 char addrbuf[INET_ADDRSTRLEN];
1149 LLE_WLOCK_ASSERT(la);
1151 /* the following is not an error when doing bridging */
1152 if (!bridged && la->lle_tbl->llt_ifp != ifp) {
1153 if (log_arp_wrong_iface)
1154 ARP_LOG(LOG_WARNING, "%s is on %s "
1155 "but got reply from %*D on %s\n",
1156 inet_ntoa_r(isaddr, addrbuf),
1157 la->lle_tbl->llt_ifp->if_xname,
1158 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1163 if ((la->la_flags & LLE_VALID) &&
1164 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) {
1165 if (la->la_flags & LLE_STATIC) {
1167 if (log_arp_permanent_modify)
1169 "%*D attempts to modify "
1170 "permanent entry for %s on %s\n",
1172 (u_char *)ar_sha(ah), ":",
1173 inet_ntoa_r(isaddr, addrbuf),
1177 if (log_arp_movements) {
1178 ARP_LOG(LOG_INFO, "%s moved from %*D "
1180 inet_ntoa_r(isaddr, addrbuf),
1182 (u_char *)la->ll_addr, ":",
1183 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1188 /* Calculate full link prepend to use in lle */
1189 linkhdrsize = sizeof(linkhdr);
1190 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
1191 &linkhdrsize, &lladdr_off) != 0)
1194 /* Check if something has changed */
1195 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 ||
1196 (la->la_flags & LLE_VALID) == 0) {
1197 /* Try to perform LLE update */
1198 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
1202 /* Clear fast path feedback request if set */
1206 arp_mark_lle_reachable(la);
1209 * The packets are all freed within the call to the output
1212 * NB: The lock MUST be released before the call to the
1215 if (la->la_hold != NULL) {
1216 m_hold = la->la_hold;
1219 lltable_fill_sa_entry(la, &sa);
1221 for (; m_hold != NULL; m_hold = m_hold_next) {
1222 m_hold_next = m_hold->m_nextpkt;
1223 m_hold->m_nextpkt = NULL;
1224 /* Avoid confusing lower layers. */
1225 m_clrprotoflags(m_hold);
1226 (*ifp->if_output)(ifp, m_hold, &sa, NULL);
1233 arp_mark_lle_reachable(struct llentry *la)
1235 int canceled, wtime;
1237 LLE_WLOCK_ASSERT(la);
1239 la->ln_state = ARP_LLINFO_REACHABLE;
1240 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
1242 if (!(la->la_flags & LLE_STATIC)) {
1244 la->la_expire = time_uptime + V_arpt_keep;
1245 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit;
1247 wtime = V_arpt_keep;
1248 canceled = callout_reset(&la->lle_timer,
1249 hz * wtime, arptimer, la);
1254 la->la_preempt = V_arp_maxtries;
1258 * Add permanent link-layer record for given interface address.
1260 static __noinline void
1261 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst)
1263 struct llentry *lle, *lle_tmp;
1266 * Interface address LLE record is considered static
1267 * because kernel code relies on LLE_STATIC flag to check
1268 * if these entries can be rewriten by arp updates.
1270 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst);
1272 log(LOG_INFO, "arp_ifinit: cannot create arp "
1273 "entry for interface address\n");
1277 IF_AFDATA_WLOCK(ifp);
1279 /* Unlink any entry if exists */
1280 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1281 if (lle_tmp != NULL)
1282 lltable_unlink_entry(LLTABLE(ifp), lle_tmp);
1284 lltable_link_entry(LLTABLE(ifp), lle);
1285 IF_AFDATA_WUNLOCK(ifp);
1287 if (lle_tmp != NULL)
1288 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED);
1290 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED);
1292 if (lle_tmp != NULL)
1293 lltable_free_entry(LLTABLE(ifp), lle_tmp);
1297 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range
1301 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS)
1304 int rexmit_count = *(int *)arg1;
1306 error = sysctl_handle_int(oidp, &rexmit_count, 0, req);
1308 /* Enforce limits on any new value that may have been set. */
1309 if (!error && req->newptr) {
1310 /* A new value was set. */
1311 if (rexmit_count < 0) {
1313 } else if (rexmit_count > MAX_GARP_RETRANSMITS) {
1314 rexmit_count = MAX_GARP_RETRANSMITS;
1316 *(int *)arg1 = rexmit_count;
1323 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to
1324 * retransmit it again. A pending callout owns a reference to the ifa.
1327 garp_rexmit(void *arg)
1329 struct in_ifaddr *ia = arg;
1331 if (callout_pending(&ia->ia_garp_timer) ||
1332 !callout_active(&ia->ia_garp_timer)) {
1333 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1334 ifa_free(&ia->ia_ifa);
1338 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet);
1341 * Drop lock while the ARP request is generated.
1343 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1345 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr,
1346 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp));
1349 * Increment the count of retransmissions. If the count has reached the
1350 * maximum value, stop sending the GARP packets. Otherwise, schedule
1351 * the callout to retransmit another GARP packet.
1353 ++ia->ia_garp_count;
1354 if (ia->ia_garp_count >= garp_rexmit_count) {
1355 ifa_free(&ia->ia_ifa);
1358 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1359 rescheduled = callout_reset(&ia->ia_garp_timer,
1360 (1 << ia->ia_garp_count) * hz,
1362 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1364 ifa_free(&ia->ia_ifa);
1372 * Start the GARP retransmit timer.
1374 * A single GARP is always transmitted when an IPv4 address is added
1375 * to an interface and that is usually sufficient. However, in some
1376 * circumstances, such as when a shared address is passed between
1377 * cluster nodes, this single GARP may occasionally be dropped or
1378 * lost. This can lead to neighbors on the network link working with a
1379 * stale ARP cache and sending packets destined for that address to
1380 * the node that previously owned the address, which may not respond.
1382 * To avoid this situation, GARP retransmits can be enabled by setting
1383 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater
1384 * than zero. The setting represents the maximum number of
1385 * retransmissions. The interval between retransmissions is calculated
1386 * using an exponential backoff algorithm, doubling each time, so the
1387 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds).
1390 garp_timer_start(struct ifaddr *ifa)
1392 struct in_ifaddr *ia = (struct in_ifaddr *) ifa;
1394 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1395 ia->ia_garp_count = 0;
1396 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz,
1397 garp_rexmit, ia) == 0) {
1400 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1404 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
1406 const struct sockaddr_in *dst_in;
1407 const struct sockaddr *dst;
1409 if (ifa->ifa_carp != NULL)
1412 dst = ifa->ifa_addr;
1413 dst_in = (const struct sockaddr_in *)dst;
1415 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY)
1417 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp));
1418 if (garp_rexmit_count > 0) {
1419 garp_timer_start(ifa);
1422 arp_add_ifa_lle(ifp, dst);
1426 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr)
1429 if (ntohl(addr.s_addr) != INADDR_ANY)
1430 arprequest(ifp, &addr, &addr, enaddr);
1434 * Sends gratuitous ARPs for each ifaddr to notify other
1435 * nodes about the address change.
1437 static __noinline void
1438 arp_handle_ifllchange(struct ifnet *ifp)
1442 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
1443 if (ifa->ifa_addr->sa_family == AF_INET)
1444 arp_ifinit(ifp, ifa);
1449 * A handler for interface link layer address change event.
1452 arp_iflladdr(void *arg __unused, struct ifnet *ifp)
1455 lltable_update_ifaddr(LLTABLE(ifp));
1457 if ((ifp->if_flags & IFF_UP) != 0)
1458 arp_handle_ifllchange(ifp);
1465 if (IS_DEFAULT_VNET(curvnet)) {
1466 netisr_register(&arp_nh);
1467 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event,
1468 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY);
1472 netisr_register_vnet(&arp_nh);
1475 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND,
1480 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH
1481 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5.
1484 vnet_arp_destroy(__unused void *arg)
1487 netisr_unregister_vnet(&arp_nh);
1489 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1490 vnet_arp_destroy, NULL);