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/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>
65 #include <net/route/nhop.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) = 16;
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__); \
181 static void arpintr(struct mbuf *);
182 static void arptimer(void *);
184 static void in_arpinput(struct mbuf *);
187 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr,
188 struct ifnet *ifp, int bridged, struct llentry *la);
189 static void arp_mark_lle_reachable(struct llentry *la, struct ifnet *ifp);
190 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp);
192 static eventhandler_tag iflladdr_tag;
194 static const struct netisr_handler arp_nh = {
196 .nh_handler = arpintr,
197 .nh_proto = NETISR_ARP,
198 .nh_policy = NETISR_POLICY_SOURCE,
202 * Timeout routine. Age arp_tab entries periodically.
207 struct llentry *lle = (struct llentry *)arg;
210 if (lle->la_flags & LLE_STATIC) {
214 if (callout_pending(&lle->lle_timer)) {
216 * Here we are a bit odd here in the treatment of
217 * active/pending. If the pending bit is set, it got
218 * rescheduled before I ran. The active
219 * bit we ignore, since if it was stopped
220 * in ll_tablefree() and was currently running
221 * it would have return 0 so the code would
222 * not have deleted it since the callout could
223 * not be stopped so we want to go through
224 * with the delete here now. If the callout
225 * was restarted, the pending bit will be back on and
226 * we just want to bail since the callout_reset would
227 * return 1 and our reference would have been removed
228 * by arpresolve() below.
233 ifp = lle->lle_tbl->llt_ifp;
234 CURVNET_SET(ifp->if_vnet);
236 switch (lle->ln_state) {
237 case ARP_LLINFO_REACHABLE:
240 * Expiration time is approaching.
241 * Request usage feedback from the datapath.
242 * Change state and re-schedule ourselves.
244 llentry_request_feedback(lle);
245 lle->ln_state = ARP_LLINFO_VERIFY;
246 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
250 case ARP_LLINFO_VERIFY:
251 if (llentry_get_hittime(lle) > 0 && lle->la_preempt > 0) {
252 /* Entry was used, issue refresh request */
253 struct epoch_tracker et;
256 dst = lle->r_l3addr.addr4;
258 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
261 arprequest(ifp, NULL, &dst, NULL);
266 /* Nothing happened. Reschedule if not too late */
267 if (lle->la_expire > time_uptime) {
268 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
274 case ARP_LLINFO_INCOMPLETE:
275 case ARP_LLINFO_DELETED:
279 if ((lle->la_flags & LLE_DELETED) == 0) {
282 if (lle->la_flags & LLE_VALID)
283 evt = LLENTRY_EXPIRED;
285 evt = LLENTRY_TIMEDOUT;
286 EVENTHANDLER_INVOKE(lle_event, lle, evt);
289 callout_stop(&lle->lle_timer);
291 /* XXX: LOR avoidance. We still have ref on lle. */
296 /* Guard against race with other llentry_free(). */
297 if (lle->la_flags & LLE_LINKED) {
299 lltable_unlink_entry(lle->lle_tbl, lle);
301 IF_AFDATA_UNLOCK(ifp);
303 size_t pkts_dropped = llentry_free(lle);
305 ARPSTAT_ADD(dropped, pkts_dropped);
306 ARPSTAT_INC(timeouts);
312 * Stores link-layer header for @ifp in format suitable for if_output()
313 * into buffer @buf. Resulting header length is stored in @bufsize.
315 * Returns 0 on success.
318 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf,
321 struct if_encap_req ereq;
324 bzero(buf, *bufsize);
325 bzero(&ereq, sizeof(ereq));
327 ereq.bufsize = *bufsize;
328 ereq.rtype = IFENCAP_LL;
329 ereq.family = AF_ARP;
330 ereq.lladdr = ar_tha(ah);
331 ereq.hdata = (u_char *)ah;
333 ereq.flags = IFENCAP_FLAG_BROADCAST;
334 error = ifp->if_requestencap(ifp, &ereq);
336 *bufsize = ereq.bufsize;
342 * Broadcast an ARP request. Caller specifies:
343 * - arp header source ip address
344 * - arp header target ip address
345 * - arp header source ethernet address
348 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip,
349 const struct in_addr *tip, u_char *enaddr)
354 u_char *carpaddr = NULL;
355 uint8_t linkhdr[LLE_MAX_LINKHDR];
364 * The caller did not supply a source address, try to find
365 * a compatible one among those assigned to this interface.
369 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
370 if (ifa->ifa_addr->sa_family != AF_INET)
374 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
376 sip = &IA_SIN(ifa)->sin_addr;
379 sip = &IA_SIN(ifa)->sin_addr;
382 if (0 == ((sip->s_addr ^ tip->s_addr) &
383 IA_MASKSIN(ifa)->sin_addr.s_addr))
384 break; /* found it. */
387 printf("%s: cannot find matching address\n", __func__);
388 return (EADDRNOTAVAIL);
392 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
394 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
396 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
398 m->m_pkthdr.len = m->m_len;
399 M_ALIGN(m, m->m_len);
400 ah = mtod(m, struct arphdr *);
401 bzero((caddr_t)ah, m->m_len);
403 mac_netinet_arp_send(ifp, m);
405 ah->ar_pro = htons(ETHERTYPE_IP);
406 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
407 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
408 ah->ar_op = htons(ARPOP_REQUEST);
409 bcopy(enaddr, ar_sha(ah), ah->ar_hln);
410 bcopy(sip, ar_spa(ah), ah->ar_pln);
411 bcopy(tip, ar_tpa(ah), ah->ar_pln);
412 sa.sa_family = AF_ARP;
415 /* Calculate link header for sending frame */
416 bzero(&ro, sizeof(ro));
417 linkhdrsize = sizeof(linkhdr);
418 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize);
419 if (error != 0 && error != EAFNOSUPPORT) {
421 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
422 if_name(ifp), error);
426 ro.ro_prepend = linkhdr;
427 ro.ro_plen = linkhdrsize;
430 m->m_flags |= M_BCAST;
431 m_clrprotoflags(m); /* Avoid confusing lower layers. */
432 error = (*ifp->if_output)(ifp, m, &sa, &ro);
433 ARPSTAT_INC(txrequests);
435 ARPSTAT_INC(txerrors);
436 ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n",
437 if_name(ifp), error);
443 arprequest(struct ifnet *ifp, const struct in_addr *sip,
444 const struct in_addr *tip, u_char *enaddr)
447 (void) arprequest_internal(ifp, sip, tip, enaddr);
451 * Resolve an IP address into an ethernet address - heavy version.
452 * Used internally by arpresolve().
453 * We have already checked that we can't use an existing lle without
454 * modification so we have to acquire an LLE_EXCLUSIVE lle lock.
456 * On success, desten and pflags are filled in and the function returns 0;
457 * If the packet must be held pending resolution, we return EWOULDBLOCK
458 * On other errors, we return the corresponding error code.
459 * Note that m_freem() handles NULL.
462 arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m,
463 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
464 struct llentry **plle)
466 struct llentry *la = NULL, *la_tmp;
478 if ((flags & LLE_CREATE) == 0)
479 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
480 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
481 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
483 char addrbuf[INET_ADDRSTRLEN];
486 "arpresolve: can't allocate llinfo for %s on %s\n",
487 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf),
493 IF_AFDATA_WLOCK(ifp);
495 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
496 /* Prefer ANY existing lle over newly-created one */
498 lltable_link_entry(LLTABLE(ifp), la);
499 IF_AFDATA_WUNLOCK(ifp);
500 if (la_tmp != NULL) {
501 lltable_free_entry(LLTABLE(ifp), la);
510 if ((la->la_flags & LLE_VALID) &&
511 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
512 if (flags & LLE_ADDRONLY) {
513 lladdr = la->ll_addr;
514 ll_len = ifp->if_addrlen;
516 lladdr = la->r_linkdata;
517 ll_len = la->r_hdrlen;
519 bcopy(lladdr, desten, ll_len);
521 /* Notify LLE code that the entry was used by datapath */
522 llentry_provide_feedback(la);
524 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR);
533 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
536 * There is an arptab entry, but no ethernet address
537 * response yet. Add the mbuf to the list, dropping
538 * the oldest packet if we have exceeded the system
542 size_t dropped = lltable_append_entry_queue(la, m, V_arp_maxhold);
543 ARPSTAT_ADD(dropped, dropped);
547 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
548 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
549 * if we have already sent arp_maxtries ARP requests. Retransmit the
550 * ARP request, but not faster than one request per second.
552 if (la->la_asked < V_arp_maxtries)
553 error = EWOULDBLOCK; /* First request. */
555 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN;
561 la->la_expire = time_uptime;
562 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down,
568 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL);
570 * Only overwrite 'error' in case of error; in case of success
571 * the proper return value was already set above.
583 * Lookups link header based on an IP address.
585 * ifp is the interface we use
586 * is_gw != 0 if @dst represents gateway to some destination
587 * m is the mbuf. May be NULL if we don't have a packet.
588 * dst is the next hop,
589 * desten is the storage to put LL header.
590 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR
592 * On success, full/partial link header and flags are filled in and
593 * the function returns 0.
594 * If the packet must be held pending resolution, we return EWOULDBLOCK
595 * On other errors, we return the corresponding error code.
596 * Note that m_freem() handles NULL.
599 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
600 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
601 struct llentry **plle)
603 struct llentry *la = NULL;
613 if (m->m_flags & M_BCAST) {
616 ifp->if_broadcastaddr, ifp->if_addrlen);
619 if (m->m_flags & M_MCAST) {
621 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
626 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst);
627 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) {
628 /* Entry found, let's copy lle info */
629 bcopy(la->r_linkdata, desten, la->r_hdrlen);
631 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR);
632 /* Notify the LLE handling code that the entry was used. */
633 llentry_provide_feedback(la);
644 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst,
645 desten, pflags, plle));
649 * Common length and type checks are done here,
650 * then the protocol-specific routine is called.
653 arpintr(struct mbuf *m)
660 ifp = m->m_pkthdr.rcvif;
662 if (m->m_len < sizeof(struct arphdr) &&
663 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
664 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n",
668 ar = mtod(m, struct arphdr *);
670 /* Check if length is sufficient */
671 if (m->m_len < arphdr_len(ar)) {
672 m = m_pullup(m, arphdr_len(ar));
674 ARP_LOG(LOG_NOTICE, "short packet received on %s\n",
678 ar = mtod(m, struct arphdr *);
683 switch (ntohs(ar->ar_hrd)) {
685 hlen = ETHER_ADDR_LEN; /* RFC 826 */
688 case ARPHRD_INFINIBAND:
689 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */
690 layer = "infiniband";
692 case ARPHRD_IEEE1394:
693 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */
697 * Restrict too long hardware addresses.
698 * Currently we are capable of handling 20-byte
699 * addresses ( sizeof(lle->ll_addr) )
701 if (ar->ar_hln >= 20)
706 "packet with unknown hardware format 0x%02d received on "
707 "%s\n", ntohs(ar->ar_hrd), if_name(ifp));
712 if (hlen != 0 && hlen != ar->ar_hln) {
714 "packet with invalid %s address length %d received on %s\n",
715 layer, ar->ar_hln, if_name(ifp));
720 ARPSTAT_INC(received);
721 switch (ntohs(ar->ar_pro)) {
733 * ARP for Internet protocols on 10 Mb/s Ethernet.
734 * Algorithm is that given in RFC 826.
735 * In addition, a sanity check is performed on the sender
736 * protocol address, to catch impersonators.
737 * We no longer handle negotiations for use of trailer protocol:
738 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
739 * along with IP replies if we wanted trailers sent to us,
740 * and also sent them in response to IP replies.
741 * This allowed either end to announce the desire to receive
743 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
744 * but formerly didn't normally send requests.
746 static int log_arp_wrong_iface = 1;
747 static int log_arp_movements = 1;
748 static int log_arp_permanent_modify = 1;
749 static int allow_multicast = 0;
751 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
752 &log_arp_wrong_iface, 0,
753 "log arp packets arriving on the wrong interface");
754 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
755 &log_arp_movements, 0,
756 "log arp replies from MACs different than the one in the cache");
757 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
758 &log_arp_permanent_modify, 0,
759 "log arp replies from MACs different than the one in the permanent arp entry");
760 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
761 &allow_multicast, 0, "accept multicast addresses");
764 in_arpinput(struct mbuf *m)
767 struct ifnet *ifp = m->m_pkthdr.rcvif;
768 struct llentry *la = NULL, *la_tmp;
770 struct in_ifaddr *ia;
772 struct in_addr isaddr, itaddr, myaddr;
773 u_int8_t *enaddr = NULL;
775 int bridged = 0, is_bridge = 0;
777 struct sockaddr_in sin;
778 struct sockaddr *dst;
779 struct nhop_object *nh;
780 uint8_t linkhdr[LLE_MAX_LINKHDR];
785 char addrbuf[INET_ADDRSTRLEN];
789 sin.sin_len = sizeof(struct sockaddr_in);
790 sin.sin_family = AF_INET;
791 sin.sin_addr.s_addr = 0;
795 if (ifp->if_type == IFT_BRIDGE)
799 * We already have checked that mbuf contains enough contiguous data
800 * to hold entire arp message according to the arp header.
802 ah = mtod(m, struct arphdr *);
805 * ARP is only for IPv4 so we can reject packets with
806 * a protocol length not equal to an IPv4 address.
808 if (ah->ar_pln != sizeof(struct in_addr)) {
809 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
810 sizeof(struct in_addr));
814 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
815 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
816 ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
820 op = ntohs(ah->ar_op);
821 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
822 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
824 if (op == ARPOP_REPLY)
825 ARPSTAT_INC(rxreplies);
828 * For a bridge, we want to check the address irrespective
829 * of the receive interface. (This will change slightly
830 * when we have clusters of interfaces).
832 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
833 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
834 ia->ia_ifp == ifp) &&
835 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
836 (ia->ia_ifa.ifa_carp == NULL ||
837 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
838 ifa_ref(&ia->ia_ifa);
842 CK_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);
850 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
851 (ia->ia_ifp->if_bridge == ifp->if_softc && \
852 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
853 addr == ia->ia_addr.sin_addr.s_addr)
855 * Check the case when bridge shares its MAC address with
856 * some of its children, so packets are claimed by bridge
857 * itself (bridge_input() does it first), but they are really
858 * meant to be destined to the bridge member.
861 CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
862 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
863 ifa_ref(&ia->ia_ifa);
869 #undef BDG_MEMBER_MATCHES_ARP
872 * No match, use the first inet address on the receive interface
873 * as a dummy address for the rest of the function.
875 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
876 if (ifa->ifa_addr->sa_family == AF_INET &&
877 (ifa->ifa_carp == NULL ||
878 (*carp_iamatch_p)(ifa, &enaddr))) {
885 * If bridging, fall back to using any inet address.
887 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL)
889 ifa_ref(&ia->ia_ifa);
892 enaddr = (u_int8_t *)IF_LLADDR(ifp);
893 carped = (ia->ia_ifa.ifa_carp != NULL);
894 myaddr = ia->ia_addr.sin_addr;
895 ifa_free(&ia->ia_ifa);
896 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
897 goto drop; /* it's from me, ignore it. */
898 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
899 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
900 "%s!\n", inet_ntoa_r(isaddr, addrbuf));
904 if (ifp->if_addrlen != ah->ar_hln) {
905 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
906 "i/f %d (ignored)\n", ifp->if_addrlen,
907 (u_char *) ar_sha(ah), ":", ah->ar_hln,
913 * Warn if another host is using the same IP address, but only if the
914 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
915 * case we suppress the warning to avoid false positive complaints of
916 * potential misconfiguration.
918 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
919 myaddr.s_addr != 0) {
920 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
921 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
922 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname);
927 if (ifp->if_flags & IFF_STATICARP)
930 bzero(&sin, sizeof(sin));
931 sin.sin_len = sizeof(struct sockaddr_in);
932 sin.sin_family = AF_INET;
933 sin.sin_addr = isaddr;
934 dst = (struct sockaddr *)&sin;
935 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
937 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
938 else if (itaddr.s_addr == myaddr.s_addr) {
940 * Request/reply to our address, but no lle exists yet.
941 * Calculate full link prepend to use in lle.
943 linkhdrsize = sizeof(linkhdr);
944 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
945 &linkhdrsize, &lladdr_off) != 0)
948 /* Allocate new entry */
949 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
952 * lle creation may fail if source address belongs
953 * to non-directly connected subnet. However, we
954 * will try to answer the request instead of dropping
959 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
962 IF_AFDATA_WLOCK(ifp);
964 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
967 * Check if lle still does not exists.
968 * If it does, that means that we either
969 * 1) have configured it explicitly, via
970 * 1a) 'arp -s' static entry or
971 * 1b) interface address static record
973 * 2) it was the result of sending first packet to-host
975 * 3) it was another arp reply packet we handled in
978 * In all cases except 3) we definitely need to prefer
979 * existing lle. For the sake of simplicity, prefer any
980 * existing lle over newly-create one.
983 lltable_link_entry(LLTABLE(ifp), la);
984 IF_AFDATA_WUNLOCK(ifp);
986 if (la_tmp == NULL) {
987 arp_mark_lle_reachable(la, ifp);
990 /* Free newly-create entry and handle packet */
991 lltable_free_entry(LLTABLE(ifp), la);
994 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
995 /* arp_check_update_lle() returns @la unlocked */
1000 if (op != ARPOP_REQUEST)
1002 ARPSTAT_INC(rxrequests);
1004 if (itaddr.s_addr == myaddr.s_addr) {
1005 /* Shortcut.. the receiving interface is the target. */
1006 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1007 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1010 * Destination address is not ours. Check if
1011 * proxyarp entry exists or proxyarp is turned on globally.
1013 struct llentry *lle;
1015 sin.sin_addr = itaddr;
1016 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
1018 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
1019 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1020 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln);
1026 if (!V_arp_proxyall)
1030 nh = fib4_lookup(ifp->if_fib, itaddr, 0, 0, 0);
1035 * Don't send proxies for nodes on the same interface
1036 * as this one came out of, or we'll get into a fight
1037 * over who claims what Ether address.
1039 if (nh->nh_ifp == ifp)
1042 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1043 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1046 * Also check that the node which sent the ARP packet
1047 * is on the interface we expect it to be on. This
1048 * avoids ARP chaos if an interface is connected to the
1052 nh = fib4_lookup(ifp->if_fib, isaddr, 0, 0, 0);
1055 if (nh->nh_ifp != ifp) {
1056 ARP_LOG(LOG_INFO, "proxy: ignoring request"
1057 " from %s via %s\n",
1058 inet_ntoa_r(isaddr, addrbuf),
1064 printf("arp: proxying for %s\n",
1065 inet_ntoa_r(itaddr, addrbuf));
1070 if (itaddr.s_addr == myaddr.s_addr &&
1071 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
1072 /* RFC 3927 link-local IPv4; always reply by broadcast. */
1073 #ifdef DEBUG_LINKLOCAL
1074 printf("arp: sending reply for link-local addr %s\n",
1075 inet_ntoa_r(itaddr, addrbuf));
1077 m->m_flags |= M_BCAST;
1078 m->m_flags &= ~M_MCAST;
1080 /* default behaviour; never reply by broadcast. */
1081 m->m_flags &= ~(M_BCAST|M_MCAST);
1083 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
1084 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
1085 ah->ar_op = htons(ARPOP_REPLY);
1086 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
1087 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
1088 m->m_pkthdr.len = m->m_len;
1089 m->m_pkthdr.rcvif = NULL;
1090 sa.sa_family = AF_ARP;
1093 /* Calculate link header for sending frame */
1094 bzero(&ro, sizeof(ro));
1095 linkhdrsize = sizeof(linkhdr);
1096 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize);
1099 * arp_fillheader() may fail due to lack of support inside encap request
1100 * routing. This is not necessary an error, AF_ARP can/should be handled
1103 if (error != 0 && error != EAFNOSUPPORT) {
1104 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
1105 if_name(ifp), error);
1109 ro.ro_prepend = linkhdr;
1110 ro.ro_plen = linkhdrsize;
1113 m_clrprotoflags(m); /* Avoid confusing lower layers. */
1114 (*ifp->if_output)(ifp, m, &sa, &ro);
1115 ARPSTAT_INC(txreplies);
1123 static struct mbuf *
1124 arp_grab_holdchain(struct llentry *la)
1128 LLE_WLOCK_ASSERT(la);
1130 chain = la->la_hold;
1138 arp_flush_holdchain(struct ifnet *ifp, struct llentry *la, struct mbuf *chain)
1140 struct mbuf *m_hold, *m_hold_next;
1141 struct sockaddr_in sin;
1146 .ro_prepend = la->r_linkdata,
1147 .ro_plen = la->r_hdrlen,
1150 lltable_fill_sa_entry(la, (struct sockaddr *)&sin);
1152 for (m_hold = chain; m_hold != NULL; m_hold = m_hold_next) {
1153 m_hold_next = m_hold->m_nextpkt;
1154 m_hold->m_nextpkt = NULL;
1155 /* Avoid confusing lower layers. */
1156 m_clrprotoflags(m_hold);
1157 (*ifp->if_output)(ifp, m_hold, (struct sockaddr *)&sin, &ro);
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)
1169 uint8_t linkhdr[LLE_MAX_LINKHDR];
1172 char addrbuf[INET_ADDRSTRLEN];
1174 LLE_WLOCK_ASSERT(la);
1176 /* the following is not an error when doing bridging */
1177 if (!bridged && la->lle_tbl->llt_ifp != ifp) {
1178 if (log_arp_wrong_iface)
1179 ARP_LOG(LOG_WARNING, "%s is on %s "
1180 "but got reply from %*D on %s\n",
1181 inet_ntoa_r(isaddr, addrbuf),
1182 la->lle_tbl->llt_ifp->if_xname,
1183 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1188 if ((la->la_flags & LLE_VALID) &&
1189 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) {
1190 if (la->la_flags & LLE_STATIC) {
1192 if (log_arp_permanent_modify)
1194 "%*D attempts to modify "
1195 "permanent entry for %s on %s\n",
1197 (u_char *)ar_sha(ah), ":",
1198 inet_ntoa_r(isaddr, addrbuf),
1202 if (log_arp_movements) {
1203 ARP_LOG(LOG_INFO, "%s moved from %*D "
1205 inet_ntoa_r(isaddr, addrbuf),
1207 (u_char *)la->ll_addr, ":",
1208 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1213 /* Calculate full link prepend to use in lle */
1214 linkhdrsize = sizeof(linkhdr);
1215 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
1216 &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,
1231 /* Clear fast path feedback request if set */
1232 llentry_mark_used(la);
1235 arp_mark_lle_reachable(la, ifp);
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) {
1247 chain = arp_grab_holdchain(la);
1249 arp_flush_holdchain(ifp, la, chain);
1255 arp_mark_lle_reachable(struct llentry *la, struct ifnet *ifp)
1257 int canceled, wtime;
1259 LLE_WLOCK_ASSERT(la);
1261 la->ln_state = ARP_LLINFO_REACHABLE;
1262 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
1264 if ((ifp->if_flags & IFF_STICKYARP) != 0)
1265 la->la_flags |= LLE_STATIC;
1267 if (!(la->la_flags & LLE_STATIC)) {
1269 la->la_expire = time_uptime + V_arpt_keep;
1270 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit;
1272 wtime = V_arpt_keep;
1273 canceled = callout_reset(&la->lle_timer,
1274 hz * wtime, arptimer, la);
1279 la->la_preempt = V_arp_maxtries;
1283 * Add permanent link-layer record for given interface address.
1285 static __noinline void
1286 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst)
1288 struct llentry *lle, *lle_tmp;
1291 * Interface address LLE record is considered static
1292 * because kernel code relies on LLE_STATIC flag to check
1293 * if these entries can be rewriten by arp updates.
1295 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst);
1297 log(LOG_INFO, "arp_ifinit: cannot create arp "
1298 "entry for interface address\n");
1302 IF_AFDATA_WLOCK(ifp);
1304 /* Unlink any entry if exists */
1305 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1306 if (lle_tmp != NULL)
1307 lltable_unlink_entry(LLTABLE(ifp), lle_tmp);
1309 lltable_link_entry(LLTABLE(ifp), lle);
1310 IF_AFDATA_WUNLOCK(ifp);
1312 if (lle_tmp != NULL)
1313 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED);
1315 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED);
1317 if (lle_tmp != NULL)
1318 lltable_free_entry(LLTABLE(ifp), lle_tmp);
1322 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range
1326 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS)
1329 int rexmit_count = *(int *)arg1;
1331 error = sysctl_handle_int(oidp, &rexmit_count, 0, req);
1333 /* Enforce limits on any new value that may have been set. */
1334 if (!error && req->newptr) {
1335 /* A new value was set. */
1336 if (rexmit_count < 0) {
1338 } else if (rexmit_count > MAX_GARP_RETRANSMITS) {
1339 rexmit_count = MAX_GARP_RETRANSMITS;
1341 *(int *)arg1 = rexmit_count;
1348 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to
1349 * retransmit it again. A pending callout owns a reference to the ifa.
1352 garp_rexmit(void *arg)
1354 struct in_ifaddr *ia = arg;
1356 if (callout_pending(&ia->ia_garp_timer) ||
1357 !callout_active(&ia->ia_garp_timer)) {
1358 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1359 ifa_free(&ia->ia_ifa);
1363 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet);
1366 * Drop lock while the ARP request is generated.
1368 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1370 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr,
1371 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp));
1374 * Increment the count of retransmissions. If the count has reached the
1375 * maximum value, stop sending the GARP packets. Otherwise, schedule
1376 * the callout to retransmit another GARP packet.
1378 ++ia->ia_garp_count;
1379 if (ia->ia_garp_count >= garp_rexmit_count) {
1380 ifa_free(&ia->ia_ifa);
1383 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1384 rescheduled = callout_reset(&ia->ia_garp_timer,
1385 (1 << ia->ia_garp_count) * hz,
1387 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1389 ifa_free(&ia->ia_ifa);
1397 * Start the GARP retransmit timer.
1399 * A single GARP is always transmitted when an IPv4 address is added
1400 * to an interface and that is usually sufficient. However, in some
1401 * circumstances, such as when a shared address is passed between
1402 * cluster nodes, this single GARP may occasionally be dropped or
1403 * lost. This can lead to neighbors on the network link working with a
1404 * stale ARP cache and sending packets destined for that address to
1405 * the node that previously owned the address, which may not respond.
1407 * To avoid this situation, GARP retransmits can be enabled by setting
1408 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater
1409 * than zero. The setting represents the maximum number of
1410 * retransmissions. The interval between retransmissions is calculated
1411 * using an exponential backoff algorithm, doubling each time, so the
1412 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds).
1415 garp_timer_start(struct ifaddr *ifa)
1417 struct in_ifaddr *ia = (struct in_ifaddr *) ifa;
1419 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1420 ia->ia_garp_count = 0;
1421 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz,
1422 garp_rexmit, ia) == 0) {
1425 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1429 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
1431 struct epoch_tracker et;
1432 const struct sockaddr_in *dst_in;
1433 const struct sockaddr *dst;
1435 if (ifa->ifa_carp != NULL)
1438 dst = ifa->ifa_addr;
1439 dst_in = (const struct sockaddr_in *)dst;
1441 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY)
1443 NET_EPOCH_ENTER(et);
1444 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp));
1446 if (garp_rexmit_count > 0) {
1447 garp_timer_start(ifa);
1450 arp_add_ifa_lle(ifp, dst);
1454 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr)
1457 if (ntohl(addr.s_addr) != INADDR_ANY)
1458 arprequest(ifp, &addr, &addr, enaddr);
1462 * Sends gratuitous ARPs for each ifaddr to notify other
1463 * nodes about the address change.
1465 static __noinline void
1466 arp_handle_ifllchange(struct ifnet *ifp)
1470 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
1471 if (ifa->ifa_addr->sa_family == AF_INET)
1472 arp_ifinit(ifp, ifa);
1477 * A handler for interface link layer address change event.
1480 arp_iflladdr(void *arg __unused, struct ifnet *ifp)
1482 /* if_bridge can update its lladdr during if_vmove(), after we've done
1483 * if_detach_internal()/dom_ifdetach(). */
1484 if (ifp->if_afdata[AF_INET] == NULL)
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);