2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1982, 1986, 1988, 1993
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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>
66 #include <net/route/nhop.h>
69 #include <netinet/in.h>
70 #include <netinet/in_fib.h>
71 #include <netinet/in_var.h>
72 #include <net/if_llatbl.h>
73 #include <netinet/if_ether.h>
75 #include <netinet/ip_carp.h>
78 #include <security/mac/mac_framework.h>
80 #define SIN(s) ((const struct sockaddr_in *)(s))
82 static struct timeval arp_lastlog;
83 static int arp_curpps;
84 static int arp_maxpps = 1;
86 /* Simple ARP state machine */
87 enum arp_llinfo_state {
88 ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */
89 ARP_LLINFO_REACHABLE, /* LLE is valid */
90 ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */
91 ARP_LLINFO_DELETED, /* LLE is deleted */
94 SYSCTL_DECL(_net_link_ether);
95 static SYSCTL_NODE(_net_link_ether, PF_INET, inet,
96 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
98 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp,
99 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
103 VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20
105 VNET_DEFINE_STATIC(int, arp_maxtries) = 5;
106 VNET_DEFINE_STATIC(int, arp_proxyall) = 0;
107 VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for
109 VNET_DEFINE_STATIC(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/
110 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */
111 VNET_PCPUSTAT_SYSINIT(arpstat);
114 VNET_PCPUSTAT_SYSUNINIT(arpstat);
117 VNET_DEFINE_STATIC(int, arp_maxhold) = 1;
119 #define V_arpt_keep VNET(arpt_keep)
120 #define V_arpt_down VNET(arpt_down)
121 #define V_arpt_rexmit VNET(arpt_rexmit)
122 #define V_arp_maxtries VNET(arp_maxtries)
123 #define V_arp_proxyall VNET(arp_proxyall)
124 #define V_arp_maxhold VNET(arp_maxhold)
126 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW,
127 &VNET_NAME(arpt_keep), 0,
128 "ARP entry lifetime in seconds");
129 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW,
130 &VNET_NAME(arp_maxtries), 0,
131 "ARP resolution attempts before returning error");
132 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW,
133 &VNET_NAME(arp_proxyall), 0,
134 "Enable proxy ARP for all suitable requests");
135 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW,
136 &VNET_NAME(arpt_down), 0,
137 "Incomplete ARP entry lifetime in seconds");
138 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat,
139 arpstat, "ARP statistics (struct arpstat, net/if_arp.h)");
140 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW,
141 &VNET_NAME(arp_maxhold), 0,
142 "Number of packets to hold per ARP entry");
143 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second,
144 CTLFLAG_RW, &arp_maxpps, 0,
145 "Maximum number of remotely triggered ARP messages that can be "
146 "logged per second");
149 * Due to the exponential backoff algorithm used for the interval between GARP
150 * retransmissions, the maximum number of retransmissions is limited for
151 * sanity. This limit corresponds to a maximum interval between retransmissions
152 * of 2^16 seconds ~= 18 hours.
154 * Making this limit more dynamic is more complicated than worthwhile,
155 * especially since sending out GARPs spaced days apart would be of little
156 * use. A maximum dynamic limit would look something like:
158 * const int max = fls(INT_MAX / hz) - 1;
160 #define MAX_GARP_RETRANSMITS 16
161 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS);
162 static int garp_rexmit_count = 0; /* GARP retransmission setting. */
164 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count,
165 CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE,
166 &garp_rexmit_count, 0, sysctl_garp_rexmit, "I",
167 "Number of times to retransmit GARP packets;"
168 " 0 to disable, maximum of 16");
170 VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */
171 #define V_arp_log_level VNET(arp_log_level)
172 SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW,
173 &VNET_NAME(arp_log_level), 0,
174 "Minimum log(9) level for recording rate limited arp log messages. "
175 "The higher will be log more (emerg=0, info=6 (default), debug=7).");
176 #define ARP_LOG(pri, ...) do { \
177 if ((pri) <= V_arp_log_level && \
178 ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \
179 log((pri), "arp: " __VA_ARGS__); \
183 static void arpintr(struct mbuf *);
184 static void arptimer(void *);
186 static void in_arpinput(struct mbuf *);
189 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr,
190 struct ifnet *ifp, int bridged, struct llentry *la);
191 static void arp_mark_lle_reachable(struct llentry *la);
192 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp);
194 static eventhandler_tag iflladdr_tag;
196 static const struct netisr_handler arp_nh = {
198 .nh_handler = arpintr,
199 .nh_proto = NETISR_ARP,
200 .nh_policy = NETISR_POLICY_SOURCE,
204 * Timeout routine. Age arp_tab entries periodically.
209 struct llentry *lle = (struct llentry *)arg;
213 if (lle->la_flags & LLE_STATIC) {
217 if (callout_pending(&lle->lle_timer)) {
219 * Here we are a bit odd here in the treatment of
220 * active/pending. If the pending bit is set, it got
221 * rescheduled before I ran. The active
222 * bit we ignore, since if it was stopped
223 * in ll_tablefree() and was currently running
224 * it would have return 0 so the code would
225 * not have deleted it since the callout could
226 * not be stopped so we want to go through
227 * with the delete here now. If the callout
228 * was restarted, the pending bit will be back on and
229 * we just want to bail since the callout_reset would
230 * return 1 and our reference would have been removed
231 * by arpresolve() below.
236 ifp = lle->lle_tbl->llt_ifp;
237 CURVNET_SET(ifp->if_vnet);
239 switch (lle->ln_state) {
240 case ARP_LLINFO_REACHABLE:
243 * Expiration time is approaching.
244 * Let's try to refresh entry if it is still
247 * Set r_skip_req to get feedback from
248 * fast path. Change state and re-schedule
254 lle->ln_state = ARP_LLINFO_VERIFY;
255 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
259 case ARP_LLINFO_VERIFY:
261 r_skip_req = lle->r_skip_req;
264 if (r_skip_req == 0 && lle->la_preempt > 0) {
265 /* Entry was used, issue refresh request */
266 struct epoch_tracker et;
269 dst = lle->r_l3addr.addr4;
271 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
274 arprequest(ifp, NULL, &dst, NULL);
279 /* Nothing happened. Reschedule if not too late */
280 if (lle->la_expire > time_uptime) {
281 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
287 case ARP_LLINFO_INCOMPLETE:
288 case ARP_LLINFO_DELETED:
292 if ((lle->la_flags & LLE_DELETED) == 0) {
295 if (lle->la_flags & LLE_VALID)
296 evt = LLENTRY_EXPIRED;
298 evt = LLENTRY_TIMEDOUT;
299 EVENTHANDLER_INVOKE(lle_event, lle, evt);
302 callout_stop(&lle->lle_timer);
304 /* XXX: LOR avoidance. We still have ref on lle. */
309 /* Guard against race with other llentry_free(). */
310 if (lle->la_flags & LLE_LINKED) {
312 lltable_unlink_entry(lle->lle_tbl, lle);
314 IF_AFDATA_UNLOCK(ifp);
316 size_t pkts_dropped = llentry_free(lle);
318 ARPSTAT_ADD(dropped, pkts_dropped);
319 ARPSTAT_INC(timeouts);
325 * Stores link-layer header for @ifp in format suitable for if_output()
326 * into buffer @buf. Resulting header length is stored in @bufsize.
328 * Returns 0 on success.
331 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf,
334 struct if_encap_req ereq;
337 bzero(buf, *bufsize);
338 bzero(&ereq, sizeof(ereq));
340 ereq.bufsize = *bufsize;
341 ereq.rtype = IFENCAP_LL;
342 ereq.family = AF_ARP;
343 ereq.lladdr = ar_tha(ah);
344 ereq.hdata = (u_char *)ah;
346 ereq.flags = IFENCAP_FLAG_BROADCAST;
347 error = ifp->if_requestencap(ifp, &ereq);
349 *bufsize = ereq.bufsize;
356 * Broadcast an ARP request. Caller specifies:
357 * - arp header source ip address
358 * - arp header target ip address
359 * - arp header source ethernet address
362 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip,
363 const struct in_addr *tip, u_char *enaddr)
368 u_char *carpaddr = NULL;
369 uint8_t linkhdr[LLE_MAX_LINKHDR];
378 * The caller did not supply a source address, try to find
379 * a compatible one among those assigned to this interface.
383 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
384 if (ifa->ifa_addr->sa_family != AF_INET)
388 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
390 sip = &IA_SIN(ifa)->sin_addr;
393 sip = &IA_SIN(ifa)->sin_addr;
396 if (0 == ((sip->s_addr ^ tip->s_addr) &
397 IA_MASKSIN(ifa)->sin_addr.s_addr))
398 break; /* found it. */
401 printf("%s: cannot find matching address\n", __func__);
402 return (EADDRNOTAVAIL);
406 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
408 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
410 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
412 m->m_pkthdr.len = m->m_len;
413 M_ALIGN(m, m->m_len);
414 ah = mtod(m, struct arphdr *);
415 bzero((caddr_t)ah, m->m_len);
417 mac_netinet_arp_send(ifp, m);
419 ah->ar_pro = htons(ETHERTYPE_IP);
420 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
421 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
422 ah->ar_op = htons(ARPOP_REQUEST);
423 bcopy(enaddr, ar_sha(ah), ah->ar_hln);
424 bcopy(sip, ar_spa(ah), ah->ar_pln);
425 bcopy(tip, ar_tpa(ah), ah->ar_pln);
426 sa.sa_family = AF_ARP;
429 /* Calculate link header for sending frame */
430 bzero(&ro, sizeof(ro));
431 linkhdrsize = sizeof(linkhdr);
432 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize);
433 if (error != 0 && error != EAFNOSUPPORT) {
434 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
435 if_name(ifp), error);
439 ro.ro_prepend = linkhdr;
440 ro.ro_plen = linkhdrsize;
443 m->m_flags |= M_BCAST;
444 m_clrprotoflags(m); /* Avoid confusing lower layers. */
445 error = (*ifp->if_output)(ifp, m, &sa, &ro);
446 ARPSTAT_INC(txrequests);
448 ARPSTAT_INC(txerrors);
449 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n",
450 if_name(ifp), error);
456 arprequest(struct ifnet *ifp, const struct in_addr *sip,
457 const struct in_addr *tip, u_char *enaddr)
460 (void) arprequest_internal(ifp, sip, tip, enaddr);
464 * Resolve an IP address into an ethernet address - heavy version.
465 * Used internally by arpresolve().
466 * We have already checked that we can't use an existing lle without
467 * modification so we have to acquire an LLE_EXCLUSIVE lle lock.
469 * On success, desten and pflags are filled in and the function returns 0;
470 * If the packet must be held pending resolution, we return EWOULDBLOCK
471 * On other errors, we return the corresponding error code.
472 * Note that m_freem() handles NULL.
475 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m,
476 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
477 struct llentry **plle)
479 struct llentry *la = NULL, *la_tmp;
480 struct mbuf *curr = NULL;
481 struct mbuf *next = NULL;
493 if ((flags & LLE_CREATE) == 0)
494 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
495 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
496 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
498 char addrbuf[INET_ADDRSTRLEN];
501 "arpresolve: can't allocate llinfo for %s on %s\n",
502 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf),
508 IF_AFDATA_WLOCK(ifp);
510 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
511 /* Prefer ANY existing lle over newly-created one */
513 lltable_link_entry(LLTABLE(ifp), la);
514 IF_AFDATA_WUNLOCK(ifp);
515 if (la_tmp != NULL) {
516 lltable_free_entry(LLTABLE(ifp), la);
525 if ((la->la_flags & LLE_VALID) &&
526 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
527 if (flags & LLE_ADDRONLY) {
528 lladdr = la->ll_addr;
529 ll_len = ifp->if_addrlen;
531 lladdr = la->r_linkdata;
532 ll_len = la->r_hdrlen;
534 bcopy(lladdr, desten, ll_len);
536 /* Notify LLE code that the entry was used by datapath */
537 llentry_mark_used(la);
539 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR);
548 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
550 * There is an arptab entry, but no ethernet address
551 * response yet. Add the mbuf to the list, dropping
552 * the oldest packet if we have exceeded the system
556 if (la->la_numheld >= V_arp_maxhold) {
557 if (la->la_hold != NULL) {
558 next = la->la_hold->m_nextpkt;
559 m_freem(la->la_hold);
562 ARPSTAT_INC(dropped);
565 if (la->la_hold != NULL) {
567 while (curr->m_nextpkt != NULL)
568 curr = curr->m_nextpkt;
575 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
576 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
577 * if we have already sent arp_maxtries ARP requests. Retransmit the
578 * ARP request, but not faster than one request per second.
580 if (la->la_asked < V_arp_maxtries)
581 error = EWOULDBLOCK; /* First request. */
583 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN;
589 la->la_expire = time_uptime;
590 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down,
596 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL);
598 * Only overwrite 'error' in case of error; in case of success
599 * the proper return value was already set above.
611 * Lookups link header based on an IP address.
613 * ifp is the interface we use
614 * is_gw != 0 if @dst represents gateway to some destination
615 * m is the mbuf. May be NULL if we don't have a packet.
616 * dst is the next hop,
617 * desten is the storage to put LL header.
618 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR
620 * On success, full/partial link header and flags are filled in and
621 * the function returns 0.
622 * If the packet must be held pending resolution, we return EWOULDBLOCK
623 * On other errors, we return the corresponding error code.
624 * Note that m_freem() handles NULL.
627 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
628 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
629 struct llentry **plle)
631 struct llentry *la = NULL;
641 if (m->m_flags & M_BCAST) {
644 ifp->if_broadcastaddr, ifp->if_addrlen);
647 if (m->m_flags & M_MCAST) {
649 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
654 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst);
655 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) {
656 /* Entry found, let's copy lle info */
657 bcopy(la->r_linkdata, desten, la->r_hdrlen);
659 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR);
660 /* Notify the LLE handling code that the entry was used. */
661 llentry_mark_used(la);
672 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst,
673 desten, pflags, plle));
677 * Common length and type checks are done here,
678 * then the protocol-specific routine is called.
681 arpintr(struct mbuf *m)
688 ifp = m->m_pkthdr.rcvif;
690 if (m->m_len < sizeof(struct arphdr) &&
691 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
692 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n",
696 ar = mtod(m, struct arphdr *);
698 /* Check if length is sufficient */
699 if (m->m_len < arphdr_len(ar)) {
700 m = m_pullup(m, arphdr_len(ar));
702 ARP_LOG(LOG_NOTICE, "short packet received on %s\n",
706 ar = mtod(m, struct arphdr *);
711 switch (ntohs(ar->ar_hrd)) {
713 hlen = ETHER_ADDR_LEN; /* RFC 826 */
716 case ARPHRD_INFINIBAND:
717 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */
718 layer = "infiniband";
720 case ARPHRD_IEEE1394:
721 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */
725 * Restrict too long hardware addresses.
726 * Currently we are capable of handling 20-byte
727 * addresses ( sizeof(lle->ll_addr) )
729 if (ar->ar_hln >= 20)
734 "packet with unknown hardware format 0x%02d received on "
735 "%s\n", ntohs(ar->ar_hrd), if_name(ifp));
740 if (hlen != 0 && hlen != ar->ar_hln) {
742 "packet with invalid %s address length %d received on %s\n",
743 layer, ar->ar_hln, if_name(ifp));
748 ARPSTAT_INC(received);
749 switch (ntohs(ar->ar_pro)) {
761 * ARP for Internet protocols on 10 Mb/s Ethernet.
762 * Algorithm is that given in RFC 826.
763 * In addition, a sanity check is performed on the sender
764 * protocol address, to catch impersonators.
765 * We no longer handle negotiations for use of trailer protocol:
766 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
767 * along with IP replies if we wanted trailers sent to us,
768 * and also sent them in response to IP replies.
769 * This allowed either end to announce the desire to receive
771 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
772 * but formerly didn't normally send requests.
774 static int log_arp_wrong_iface = 1;
775 static int log_arp_movements = 1;
776 static int log_arp_permanent_modify = 1;
777 static int allow_multicast = 0;
779 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
780 &log_arp_wrong_iface, 0,
781 "log arp packets arriving on the wrong interface");
782 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
783 &log_arp_movements, 0,
784 "log arp replies from MACs different than the one in the cache");
785 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
786 &log_arp_permanent_modify, 0,
787 "log arp replies from MACs different than the one in the permanent arp entry");
788 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
789 &allow_multicast, 0, "accept multicast addresses");
792 in_arpinput(struct mbuf *m)
794 struct rm_priotracker in_ifa_tracker;
796 struct ifnet *ifp = m->m_pkthdr.rcvif;
797 struct llentry *la = NULL, *la_tmp;
799 struct in_ifaddr *ia;
801 struct in_addr isaddr, itaddr, myaddr;
802 u_int8_t *enaddr = NULL;
804 int bridged = 0, is_bridge = 0;
806 struct sockaddr_in sin;
807 struct sockaddr *dst;
808 struct nhop_object *nh;
809 uint8_t linkhdr[LLE_MAX_LINKHDR];
814 char addrbuf[INET_ADDRSTRLEN];
818 sin.sin_len = sizeof(struct sockaddr_in);
819 sin.sin_family = AF_INET;
820 sin.sin_addr.s_addr = 0;
824 if (ifp->if_type == IFT_BRIDGE)
828 * We already have checked that mbuf contains enough contiguous data
829 * to hold entire arp message according to the arp header.
831 ah = mtod(m, struct arphdr *);
834 * ARP is only for IPv4 so we can reject packets with
835 * a protocol length not equal to an IPv4 address.
837 if (ah->ar_pln != sizeof(struct in_addr)) {
838 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
839 sizeof(struct in_addr));
843 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
844 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
845 ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
849 op = ntohs(ah->ar_op);
850 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
851 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
853 if (op == ARPOP_REPLY)
854 ARPSTAT_INC(rxreplies);
857 * For a bridge, we want to check the address irrespective
858 * of the receive interface. (This will change slightly
859 * when we have clusters of interfaces).
861 IN_IFADDR_RLOCK(&in_ifa_tracker);
862 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
863 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
864 ia->ia_ifp == ifp) &&
865 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
866 (ia->ia_ifa.ifa_carp == NULL ||
867 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
868 ifa_ref(&ia->ia_ifa);
869 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
873 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
874 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
875 ia->ia_ifp == ifp) &&
876 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
877 ifa_ref(&ia->ia_ifa);
878 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
882 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
883 (ia->ia_ifp->if_bridge == ifp->if_softc && \
884 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
885 addr == ia->ia_addr.sin_addr.s_addr)
887 * Check the case when bridge shares its MAC address with
888 * some of its children, so packets are claimed by bridge
889 * itself (bridge_input() does it first), but they are really
890 * meant to be destined to the bridge member.
893 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
894 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
895 ifa_ref(&ia->ia_ifa);
897 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
902 #undef BDG_MEMBER_MATCHES_ARP
903 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
906 * No match, use the first inet address on the receive interface
907 * as a dummy address for the rest of the function.
909 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
910 if (ifa->ifa_addr->sa_family == AF_INET &&
911 (ifa->ifa_carp == NULL ||
912 (*carp_iamatch_p)(ifa, &enaddr))) {
919 * If bridging, fall back to using any inet address.
921 IN_IFADDR_RLOCK(&in_ifa_tracker);
922 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
923 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
926 ifa_ref(&ia->ia_ifa);
927 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
930 enaddr = (u_int8_t *)IF_LLADDR(ifp);
931 carped = (ia->ia_ifa.ifa_carp != NULL);
932 myaddr = ia->ia_addr.sin_addr;
933 ifa_free(&ia->ia_ifa);
934 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
935 goto drop; /* it's from me, ignore it. */
936 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
937 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
938 "%s!\n", inet_ntoa_r(isaddr, addrbuf));
942 if (ifp->if_addrlen != ah->ar_hln) {
943 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
944 "i/f %d (ignored)\n", ifp->if_addrlen,
945 (u_char *) ar_sha(ah), ":", ah->ar_hln,
951 * Warn if another host is using the same IP address, but only if the
952 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
953 * case we suppress the warning to avoid false positive complaints of
954 * potential misconfiguration.
956 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
957 myaddr.s_addr != 0) {
958 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
959 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
960 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname);
965 if (ifp->if_flags & IFF_STATICARP)
968 bzero(&sin, sizeof(sin));
969 sin.sin_len = sizeof(struct sockaddr_in);
970 sin.sin_family = AF_INET;
971 sin.sin_addr = isaddr;
972 dst = (struct sockaddr *)&sin;
973 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
975 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
976 else if (itaddr.s_addr == myaddr.s_addr) {
978 * Request/reply to our address, but no lle exists yet.
979 * Calculate full link prepend to use in lle.
981 linkhdrsize = sizeof(linkhdr);
982 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
983 &linkhdrsize, &lladdr_off) != 0)
986 /* Allocate new entry */
987 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
991 * lle creation may fail if source address belongs
992 * to non-directly connected subnet. However, we
993 * will try to answer the request instead of dropping
998 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
1001 IF_AFDATA_WLOCK(ifp);
1003 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1006 * Check if lle still does not exists.
1007 * If it does, that means that we either
1008 * 1) have configured it explicitly, via
1009 * 1a) 'arp -s' static entry or
1010 * 1b) interface address static record
1012 * 2) it was the result of sending first packet to-host
1014 * 3) it was another arp reply packet we handled in
1017 * In all cases except 3) we definitely need to prefer
1018 * existing lle. For the sake of simplicity, prefer any
1019 * existing lle over newly-create one.
1022 lltable_link_entry(LLTABLE(ifp), la);
1023 IF_AFDATA_WUNLOCK(ifp);
1025 if (la_tmp == NULL) {
1026 arp_mark_lle_reachable(la);
1029 /* Free newly-create entry and handle packet */
1030 lltable_free_entry(LLTABLE(ifp), la);
1033 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
1034 /* arp_check_update_lle() returns @la unlocked */
1039 if (op != ARPOP_REQUEST)
1041 ARPSTAT_INC(rxrequests);
1043 if (itaddr.s_addr == myaddr.s_addr) {
1044 /* Shortcut.. the receiving interface is the target. */
1045 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1046 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1049 * Destination address is not ours. Check if
1050 * proxyarp entry exists or proxyarp is turned on globally.
1052 struct llentry *lle;
1054 sin.sin_addr = itaddr;
1055 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
1057 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
1058 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1059 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln);
1066 if (!V_arp_proxyall)
1070 nh = fib4_lookup(ifp->if_fib, itaddr, 0, 0, 0);
1075 * Don't send proxies for nodes on the same interface
1076 * as this one came out of, or we'll get into a fight
1077 * over who claims what Ether address.
1079 if (nh->nh_ifp == ifp)
1082 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1083 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1086 * Also check that the node which sent the ARP packet
1087 * is on the interface we expect it to be on. This
1088 * avoids ARP chaos if an interface is connected to the
1092 nh = fib4_lookup(ifp->if_fib, isaddr, 0, 0, 0);
1095 if (nh->nh_ifp != ifp) {
1096 ARP_LOG(LOG_INFO, "proxy: ignoring request"
1097 " from %s via %s\n",
1098 inet_ntoa_r(isaddr, addrbuf),
1104 printf("arp: proxying for %s\n",
1105 inet_ntoa_r(itaddr, addrbuf));
1110 if (itaddr.s_addr == myaddr.s_addr &&
1111 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
1112 /* RFC 3927 link-local IPv4; always reply by broadcast. */
1113 #ifdef DEBUG_LINKLOCAL
1114 printf("arp: sending reply for link-local addr %s\n",
1115 inet_ntoa_r(itaddr, addrbuf));
1117 m->m_flags |= M_BCAST;
1118 m->m_flags &= ~M_MCAST;
1120 /* default behaviour; never reply by broadcast. */
1121 m->m_flags &= ~(M_BCAST|M_MCAST);
1123 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
1124 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
1125 ah->ar_op = htons(ARPOP_REPLY);
1126 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
1127 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
1128 m->m_pkthdr.len = m->m_len;
1129 m->m_pkthdr.rcvif = NULL;
1130 sa.sa_family = AF_ARP;
1133 /* Calculate link header for sending frame */
1134 bzero(&ro, sizeof(ro));
1135 linkhdrsize = sizeof(linkhdr);
1136 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize);
1139 * arp_fillheader() may fail due to lack of support inside encap request
1140 * routing. This is not necessary an error, AF_ARP can/should be handled
1143 if (error != 0 && error != EAFNOSUPPORT) {
1144 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
1145 if_name(ifp), error);
1149 ro.ro_prepend = linkhdr;
1150 ro.ro_plen = linkhdrsize;
1153 m_clrprotoflags(m); /* Avoid confusing lower layers. */
1154 (*ifp->if_output)(ifp, m, &sa, &ro);
1155 ARPSTAT_INC(txreplies);
1164 * Checks received arp data against existing @la.
1165 * Updates lle state/performs notification if necessary.
1168 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp,
1169 int bridged, struct llentry *la)
1172 struct mbuf *m_hold, *m_hold_next;
1173 uint8_t linkhdr[LLE_MAX_LINKHDR];
1176 char addrbuf[INET_ADDRSTRLEN];
1178 LLE_WLOCK_ASSERT(la);
1180 /* the following is not an error when doing bridging */
1181 if (!bridged && la->lle_tbl->llt_ifp != ifp) {
1182 if (log_arp_wrong_iface)
1183 ARP_LOG(LOG_WARNING, "%s is on %s "
1184 "but got reply from %*D on %s\n",
1185 inet_ntoa_r(isaddr, addrbuf),
1186 la->lle_tbl->llt_ifp->if_xname,
1187 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1192 if ((la->la_flags & LLE_VALID) &&
1193 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) {
1194 if (la->la_flags & LLE_STATIC) {
1196 if (log_arp_permanent_modify)
1198 "%*D attempts to modify "
1199 "permanent entry for %s on %s\n",
1201 (u_char *)ar_sha(ah), ":",
1202 inet_ntoa_r(isaddr, addrbuf),
1206 if (log_arp_movements) {
1207 ARP_LOG(LOG_INFO, "%s moved from %*D "
1209 inet_ntoa_r(isaddr, addrbuf),
1211 (u_char *)la->ll_addr, ":",
1212 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1217 /* Calculate full link prepend to use in lle */
1218 linkhdrsize = sizeof(linkhdr);
1219 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
1220 &linkhdrsize, &lladdr_off) != 0)
1223 /* Check if something has changed */
1224 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 ||
1225 (la->la_flags & LLE_VALID) == 0) {
1226 /* Try to perform LLE update */
1227 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
1231 /* Clear fast path feedback request if set */
1235 arp_mark_lle_reachable(la);
1238 * The packets are all freed within the call to the output
1241 * NB: The lock MUST be released before the call to the
1244 if (la->la_hold != NULL) {
1245 m_hold = la->la_hold;
1248 lltable_fill_sa_entry(la, &sa);
1250 for (; m_hold != NULL; m_hold = m_hold_next) {
1251 m_hold_next = m_hold->m_nextpkt;
1252 m_hold->m_nextpkt = NULL;
1253 /* Avoid confusing lower layers. */
1254 m_clrprotoflags(m_hold);
1255 (*ifp->if_output)(ifp, m_hold, &sa, NULL);
1262 arp_mark_lle_reachable(struct llentry *la)
1264 int canceled, wtime;
1266 LLE_WLOCK_ASSERT(la);
1268 la->ln_state = ARP_LLINFO_REACHABLE;
1269 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
1271 if (!(la->la_flags & LLE_STATIC)) {
1273 la->la_expire = time_uptime + V_arpt_keep;
1274 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit;
1276 wtime = V_arpt_keep;
1277 canceled = callout_reset(&la->lle_timer,
1278 hz * wtime, arptimer, la);
1283 la->la_preempt = V_arp_maxtries;
1287 * Add permanent link-layer record for given interface address.
1289 static __noinline void
1290 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst)
1292 struct llentry *lle, *lle_tmp;
1295 * Interface address LLE record is considered static
1296 * because kernel code relies on LLE_STATIC flag to check
1297 * if these entries can be rewriten by arp updates.
1299 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst);
1301 log(LOG_INFO, "arp_ifinit: cannot create arp "
1302 "entry for interface address\n");
1306 IF_AFDATA_WLOCK(ifp);
1308 /* Unlink any entry if exists */
1309 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1310 if (lle_tmp != NULL)
1311 lltable_unlink_entry(LLTABLE(ifp), lle_tmp);
1313 lltable_link_entry(LLTABLE(ifp), lle);
1314 IF_AFDATA_WUNLOCK(ifp);
1316 if (lle_tmp != NULL)
1317 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED);
1319 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED);
1321 if (lle_tmp != NULL)
1322 lltable_free_entry(LLTABLE(ifp), lle_tmp);
1326 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range
1330 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS)
1333 int rexmit_count = *(int *)arg1;
1335 error = sysctl_handle_int(oidp, &rexmit_count, 0, req);
1337 /* Enforce limits on any new value that may have been set. */
1338 if (!error && req->newptr) {
1339 /* A new value was set. */
1340 if (rexmit_count < 0) {
1342 } else if (rexmit_count > MAX_GARP_RETRANSMITS) {
1343 rexmit_count = MAX_GARP_RETRANSMITS;
1345 *(int *)arg1 = rexmit_count;
1352 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to
1353 * retransmit it again. A pending callout owns a reference to the ifa.
1356 garp_rexmit(void *arg)
1358 struct in_ifaddr *ia = arg;
1360 if (callout_pending(&ia->ia_garp_timer) ||
1361 !callout_active(&ia->ia_garp_timer)) {
1362 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1363 ifa_free(&ia->ia_ifa);
1367 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet);
1370 * Drop lock while the ARP request is generated.
1372 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1374 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr,
1375 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp));
1378 * Increment the count of retransmissions. If the count has reached the
1379 * maximum value, stop sending the GARP packets. Otherwise, schedule
1380 * the callout to retransmit another GARP packet.
1382 ++ia->ia_garp_count;
1383 if (ia->ia_garp_count >= garp_rexmit_count) {
1384 ifa_free(&ia->ia_ifa);
1387 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1388 rescheduled = callout_reset(&ia->ia_garp_timer,
1389 (1 << ia->ia_garp_count) * hz,
1391 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1393 ifa_free(&ia->ia_ifa);
1401 * Start the GARP retransmit timer.
1403 * A single GARP is always transmitted when an IPv4 address is added
1404 * to an interface and that is usually sufficient. However, in some
1405 * circumstances, such as when a shared address is passed between
1406 * cluster nodes, this single GARP may occasionally be dropped or
1407 * lost. This can lead to neighbors on the network link working with a
1408 * stale ARP cache and sending packets destined for that address to
1409 * the node that previously owned the address, which may not respond.
1411 * To avoid this situation, GARP retransmits can be enabled by setting
1412 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater
1413 * than zero. The setting represents the maximum number of
1414 * retransmissions. The interval between retransmissions is calculated
1415 * using an exponential backoff algorithm, doubling each time, so the
1416 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds).
1419 garp_timer_start(struct ifaddr *ifa)
1421 struct in_ifaddr *ia = (struct in_ifaddr *) ifa;
1423 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1424 ia->ia_garp_count = 0;
1425 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz,
1426 garp_rexmit, ia) == 0) {
1429 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1433 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
1435 struct epoch_tracker et;
1436 const struct sockaddr_in *dst_in;
1437 const struct sockaddr *dst;
1439 if (ifa->ifa_carp != NULL)
1442 dst = ifa->ifa_addr;
1443 dst_in = (const struct sockaddr_in *)dst;
1445 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY)
1447 NET_EPOCH_ENTER(et);
1448 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp));
1450 if (garp_rexmit_count > 0) {
1451 garp_timer_start(ifa);
1454 arp_add_ifa_lle(ifp, dst);
1458 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr)
1461 if (ntohl(addr.s_addr) != INADDR_ANY)
1462 arprequest(ifp, &addr, &addr, enaddr);
1466 * Sends gratuitous ARPs for each ifaddr to notify other
1467 * nodes about the address change.
1469 static __noinline void
1470 arp_handle_ifllchange(struct ifnet *ifp)
1474 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
1475 if (ifa->ifa_addr->sa_family == AF_INET)
1476 arp_ifinit(ifp, ifa);
1481 * A handler for interface link layer address change event.
1484 arp_iflladdr(void *arg __unused, struct ifnet *ifp)
1487 lltable_update_ifaddr(LLTABLE(ifp));
1489 if ((ifp->if_flags & IFF_UP) != 0)
1490 arp_handle_ifllchange(ifp);
1497 if (IS_DEFAULT_VNET(curvnet)) {
1498 netisr_register(&arp_nh);
1499 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event,
1500 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY);
1504 netisr_register_vnet(&arp_nh);
1507 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND,
1512 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH
1513 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5.
1516 vnet_arp_destroy(__unused void *arg)
1519 netisr_unregister_vnet(&arp_nh);
1521 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1522 vnet_arp_destroy, NULL);