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) = 16;
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__); \
182 static void arpintr(struct mbuf *);
183 static void arptimer(void *);
185 static void in_arpinput(struct mbuf *);
188 static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr,
189 struct ifnet *ifp, int bridged, struct llentry *la);
190 static void arp_mark_lle_reachable(struct llentry *la);
191 static void arp_iflladdr(void *arg __unused, struct ifnet *ifp);
193 static eventhandler_tag iflladdr_tag;
195 static const struct netisr_handler arp_nh = {
197 .nh_handler = arpintr,
198 .nh_proto = NETISR_ARP,
199 .nh_policy = NETISR_POLICY_SOURCE,
203 * Timeout routine. Age arp_tab entries periodically.
208 struct llentry *lle = (struct llentry *)arg;
211 if (lle->la_flags & LLE_STATIC) {
215 if (callout_pending(&lle->lle_timer)) {
217 * Here we are a bit odd here in the treatment of
218 * active/pending. If the pending bit is set, it got
219 * rescheduled before I ran. The active
220 * bit we ignore, since if it was stopped
221 * in ll_tablefree() and was currently running
222 * it would have return 0 so the code would
223 * not have deleted it since the callout could
224 * not be stopped so we want to go through
225 * with the delete here now. If the callout
226 * was restarted, the pending bit will be back on and
227 * we just want to bail since the callout_reset would
228 * return 1 and our reference would have been removed
229 * by arpresolve() below.
234 ifp = lle->lle_tbl->llt_ifp;
235 CURVNET_SET(ifp->if_vnet);
237 switch (lle->ln_state) {
238 case ARP_LLINFO_REACHABLE:
241 * Expiration time is approaching.
242 * Request usage feedback from the datapath.
243 * Change state and re-schedule ourselves.
245 llentry_request_feedback(lle);
246 lle->ln_state = ARP_LLINFO_VERIFY;
247 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
251 case ARP_LLINFO_VERIFY:
252 if (llentry_get_hittime(lle) > 0 && lle->la_preempt > 0) {
253 /* Entry was used, issue refresh request */
254 struct epoch_tracker et;
257 dst = lle->r_l3addr.addr4;
259 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
262 arprequest(ifp, NULL, &dst, NULL);
267 /* Nothing happened. Reschedule if not too late */
268 if (lle->la_expire > time_uptime) {
269 callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
275 case ARP_LLINFO_INCOMPLETE:
276 case ARP_LLINFO_DELETED:
280 if ((lle->la_flags & LLE_DELETED) == 0) {
283 if (lle->la_flags & LLE_VALID)
284 evt = LLENTRY_EXPIRED;
286 evt = LLENTRY_TIMEDOUT;
287 EVENTHANDLER_INVOKE(lle_event, lle, evt);
290 callout_stop(&lle->lle_timer);
292 /* XXX: LOR avoidance. We still have ref on lle. */
297 /* Guard against race with other llentry_free(). */
298 if (lle->la_flags & LLE_LINKED) {
300 lltable_unlink_entry(lle->lle_tbl, lle);
302 IF_AFDATA_UNLOCK(ifp);
304 size_t pkts_dropped = llentry_free(lle);
306 ARPSTAT_ADD(dropped, pkts_dropped);
307 ARPSTAT_INC(timeouts);
313 * Stores link-layer header for @ifp in format suitable for if_output()
314 * into buffer @buf. Resulting header length is stored in @bufsize.
316 * Returns 0 on success.
319 arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf,
322 struct if_encap_req ereq;
325 bzero(buf, *bufsize);
326 bzero(&ereq, sizeof(ereq));
328 ereq.bufsize = *bufsize;
329 ereq.rtype = IFENCAP_LL;
330 ereq.family = AF_ARP;
331 ereq.lladdr = ar_tha(ah);
332 ereq.hdata = (u_char *)ah;
334 ereq.flags = IFENCAP_FLAG_BROADCAST;
335 error = ifp->if_requestencap(ifp, &ereq);
337 *bufsize = ereq.bufsize;
343 * Broadcast an ARP request. Caller specifies:
344 * - arp header source ip address
345 * - arp header target ip address
346 * - arp header source ethernet address
349 arprequest_internal(struct ifnet *ifp, const struct in_addr *sip,
350 const struct in_addr *tip, u_char *enaddr)
355 u_char *carpaddr = NULL;
356 uint8_t linkhdr[LLE_MAX_LINKHDR];
365 * The caller did not supply a source address, try to find
366 * a compatible one among those assigned to this interface.
370 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
371 if (ifa->ifa_addr->sa_family != AF_INET)
375 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
377 sip = &IA_SIN(ifa)->sin_addr;
380 sip = &IA_SIN(ifa)->sin_addr;
383 if (0 == ((sip->s_addr ^ tip->s_addr) &
384 IA_MASKSIN(ifa)->sin_addr.s_addr))
385 break; /* found it. */
388 printf("%s: cannot find matching address\n", __func__);
389 return (EADDRNOTAVAIL);
393 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
395 if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
397 m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
399 m->m_pkthdr.len = m->m_len;
400 M_ALIGN(m, m->m_len);
401 ah = mtod(m, struct arphdr *);
402 bzero((caddr_t)ah, m->m_len);
404 mac_netinet_arp_send(ifp, m);
406 ah->ar_pro = htons(ETHERTYPE_IP);
407 ah->ar_hln = ifp->if_addrlen; /* hardware address length */
408 ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
409 ah->ar_op = htons(ARPOP_REQUEST);
410 bcopy(enaddr, ar_sha(ah), ah->ar_hln);
411 bcopy(sip, ar_spa(ah), ah->ar_pln);
412 bcopy(tip, ar_tpa(ah), ah->ar_pln);
413 sa.sa_family = AF_ARP;
416 /* Calculate link header for sending frame */
417 bzero(&ro, sizeof(ro));
418 linkhdrsize = sizeof(linkhdr);
419 error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize);
420 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;
467 struct mbuf *curr = NULL;
468 struct mbuf *next = NULL;
480 if ((flags & LLE_CREATE) == 0)
481 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
482 if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
483 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
485 char addrbuf[INET_ADDRSTRLEN];
488 "arpresolve: can't allocate llinfo for %s on %s\n",
489 inet_ntoa_r(SIN(dst)->sin_addr, addrbuf),
495 IF_AFDATA_WLOCK(ifp);
497 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
498 /* Prefer ANY existing lle over newly-created one */
500 lltable_link_entry(LLTABLE(ifp), la);
501 IF_AFDATA_WUNLOCK(ifp);
502 if (la_tmp != NULL) {
503 lltable_free_entry(LLTABLE(ifp), la);
512 if ((la->la_flags & LLE_VALID) &&
513 ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
514 if (flags & LLE_ADDRONLY) {
515 lladdr = la->ll_addr;
516 ll_len = ifp->if_addrlen;
518 lladdr = la->r_linkdata;
519 ll_len = la->r_hdrlen;
521 bcopy(lladdr, desten, ll_len);
523 /* Notify LLE code that the entry was used by datapath */
524 llentry_provide_feedback(la);
526 *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR);
535 renew = (la->la_asked == 0 || la->la_expire != time_uptime);
537 * There is an arptab entry, but no ethernet address
538 * response yet. Add the mbuf to the list, dropping
539 * the oldest packet if we have exceeded the system
543 if (la->la_numheld >= V_arp_maxhold) {
544 if (la->la_hold != NULL) {
545 next = la->la_hold->m_nextpkt;
546 m_freem(la->la_hold);
549 ARPSTAT_INC(dropped);
552 if (la->la_hold != NULL) {
554 while (curr->m_nextpkt != NULL)
555 curr = curr->m_nextpkt;
562 * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
563 * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
564 * if we have already sent arp_maxtries ARP requests. Retransmit the
565 * ARP request, but not faster than one request per second.
567 if (la->la_asked < V_arp_maxtries)
568 error = EWOULDBLOCK; /* First request. */
570 error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN;
576 la->la_expire = time_uptime;
577 canceled = callout_reset(&la->lle_timer, hz * V_arpt_down,
583 e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL);
585 * Only overwrite 'error' in case of error; in case of success
586 * the proper return value was already set above.
598 * Lookups link header based on an IP address.
600 * ifp is the interface we use
601 * is_gw != 0 if @dst represents gateway to some destination
602 * m is the mbuf. May be NULL if we don't have a packet.
603 * dst is the next hop,
604 * desten is the storage to put LL header.
605 * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR
607 * On success, full/partial link header and flags are filled in and
608 * the function returns 0.
609 * If the packet must be held pending resolution, we return EWOULDBLOCK
610 * On other errors, we return the corresponding error code.
611 * Note that m_freem() handles NULL.
614 arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
615 const struct sockaddr *dst, u_char *desten, uint32_t *pflags,
616 struct llentry **plle)
618 struct llentry *la = NULL;
628 if (m->m_flags & M_BCAST) {
631 ifp->if_broadcastaddr, ifp->if_addrlen);
634 if (m->m_flags & M_MCAST) {
636 ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
641 la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst);
642 if (la != NULL && (la->r_flags & RLLE_VALID) != 0) {
643 /* Entry found, let's copy lle info */
644 bcopy(la->r_linkdata, desten, la->r_hdrlen);
646 *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR);
647 /* Notify the LLE handling code that the entry was used. */
648 llentry_provide_feedback(la);
659 return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst,
660 desten, pflags, plle));
664 * Common length and type checks are done here,
665 * then the protocol-specific routine is called.
668 arpintr(struct mbuf *m)
675 ifp = m->m_pkthdr.rcvif;
677 if (m->m_len < sizeof(struct arphdr) &&
678 ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
679 ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n",
683 ar = mtod(m, struct arphdr *);
685 /* Check if length is sufficient */
686 if (m->m_len < arphdr_len(ar)) {
687 m = m_pullup(m, arphdr_len(ar));
689 ARP_LOG(LOG_NOTICE, "short packet received on %s\n",
693 ar = mtod(m, struct arphdr *);
698 switch (ntohs(ar->ar_hrd)) {
700 hlen = ETHER_ADDR_LEN; /* RFC 826 */
703 case ARPHRD_INFINIBAND:
704 hlen = 20; /* RFC 4391, INFINIBAND_ALEN */
705 layer = "infiniband";
707 case ARPHRD_IEEE1394:
708 hlen = 0; /* SHALL be 16 */ /* RFC 2734 */
712 * Restrict too long hardware addresses.
713 * Currently we are capable of handling 20-byte
714 * addresses ( sizeof(lle->ll_addr) )
716 if (ar->ar_hln >= 20)
721 "packet with unknown hardware format 0x%02d received on "
722 "%s\n", ntohs(ar->ar_hrd), if_name(ifp));
727 if (hlen != 0 && hlen != ar->ar_hln) {
729 "packet with invalid %s address length %d received on %s\n",
730 layer, ar->ar_hln, if_name(ifp));
735 ARPSTAT_INC(received);
736 switch (ntohs(ar->ar_pro)) {
748 * ARP for Internet protocols on 10 Mb/s Ethernet.
749 * Algorithm is that given in RFC 826.
750 * In addition, a sanity check is performed on the sender
751 * protocol address, to catch impersonators.
752 * We no longer handle negotiations for use of trailer protocol:
753 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
754 * along with IP replies if we wanted trailers sent to us,
755 * and also sent them in response to IP replies.
756 * This allowed either end to announce the desire to receive
758 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
759 * but formerly didn't normally send requests.
761 static int log_arp_wrong_iface = 1;
762 static int log_arp_movements = 1;
763 static int log_arp_permanent_modify = 1;
764 static int allow_multicast = 0;
766 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
767 &log_arp_wrong_iface, 0,
768 "log arp packets arriving on the wrong interface");
769 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
770 &log_arp_movements, 0,
771 "log arp replies from MACs different than the one in the cache");
772 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
773 &log_arp_permanent_modify, 0,
774 "log arp replies from MACs different than the one in the permanent arp entry");
775 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
776 &allow_multicast, 0, "accept multicast addresses");
779 in_arpinput(struct mbuf *m)
781 struct rm_priotracker in_ifa_tracker;
783 struct ifnet *ifp = m->m_pkthdr.rcvif;
784 struct llentry *la = NULL, *la_tmp;
786 struct in_ifaddr *ia;
788 struct in_addr isaddr, itaddr, myaddr;
789 u_int8_t *enaddr = NULL;
791 int bridged = 0, is_bridge = 0;
793 struct sockaddr_in sin;
794 struct sockaddr *dst;
795 struct nhop_object *nh;
796 uint8_t linkhdr[LLE_MAX_LINKHDR];
801 char addrbuf[INET_ADDRSTRLEN];
805 sin.sin_len = sizeof(struct sockaddr_in);
806 sin.sin_family = AF_INET;
807 sin.sin_addr.s_addr = 0;
811 if (ifp->if_type == IFT_BRIDGE)
815 * We already have checked that mbuf contains enough contiguous data
816 * to hold entire arp message according to the arp header.
818 ah = mtod(m, struct arphdr *);
821 * ARP is only for IPv4 so we can reject packets with
822 * a protocol length not equal to an IPv4 address.
824 if (ah->ar_pln != sizeof(struct in_addr)) {
825 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
826 sizeof(struct in_addr));
830 if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
831 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
832 ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
836 op = ntohs(ah->ar_op);
837 (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
838 (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
840 if (op == ARPOP_REPLY)
841 ARPSTAT_INC(rxreplies);
844 * For a bridge, we want to check the address irrespective
845 * of the receive interface. (This will change slightly
846 * when we have clusters of interfaces).
848 IN_IFADDR_RLOCK(&in_ifa_tracker);
849 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
850 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
851 ia->ia_ifp == ifp) &&
852 itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
853 (ia->ia_ifa.ifa_carp == NULL ||
854 (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
855 ifa_ref(&ia->ia_ifa);
856 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
860 LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
861 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
862 ia->ia_ifp == ifp) &&
863 isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
864 ifa_ref(&ia->ia_ifa);
865 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
869 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \
870 (ia->ia_ifp->if_bridge == ifp->if_softc && \
871 !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \
872 addr == ia->ia_addr.sin_addr.s_addr)
874 * Check the case when bridge shares its MAC address with
875 * some of its children, so packets are claimed by bridge
876 * itself (bridge_input() does it first), but they are really
877 * meant to be destined to the bridge member.
880 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
881 if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
882 ifa_ref(&ia->ia_ifa);
884 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
889 #undef BDG_MEMBER_MATCHES_ARP
890 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
893 * No match, use the first inet address on the receive interface
894 * as a dummy address for the rest of the function.
896 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
897 if (ifa->ifa_addr->sa_family == AF_INET &&
898 (ifa->ifa_carp == NULL ||
899 (*carp_iamatch_p)(ifa, &enaddr))) {
906 * If bridging, fall back to using any inet address.
908 IN_IFADDR_RLOCK(&in_ifa_tracker);
909 if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
910 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
913 ifa_ref(&ia->ia_ifa);
914 IN_IFADDR_RUNLOCK(&in_ifa_tracker);
917 enaddr = (u_int8_t *)IF_LLADDR(ifp);
918 carped = (ia->ia_ifa.ifa_carp != NULL);
919 myaddr = ia->ia_addr.sin_addr;
920 ifa_free(&ia->ia_ifa);
921 if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
922 goto drop; /* it's from me, ignore it. */
923 if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
924 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
925 "%s!\n", inet_ntoa_r(isaddr, addrbuf));
929 if (ifp->if_addrlen != ah->ar_hln) {
930 ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
931 "i/f %d (ignored)\n", ifp->if_addrlen,
932 (u_char *) ar_sha(ah), ":", ah->ar_hln,
938 * Warn if another host is using the same IP address, but only if the
939 * IP address isn't 0.0.0.0, which is used for DHCP only, in which
940 * case we suppress the warning to avoid false positive complaints of
941 * potential misconfiguration.
943 if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
944 myaddr.s_addr != 0) {
945 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
946 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
947 inet_ntoa_r(isaddr, addrbuf), ifp->if_xname);
952 if (ifp->if_flags & IFF_STATICARP)
955 bzero(&sin, sizeof(sin));
956 sin.sin_len = sizeof(struct sockaddr_in);
957 sin.sin_family = AF_INET;
958 sin.sin_addr = isaddr;
959 dst = (struct sockaddr *)&sin;
960 la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
962 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
963 else if (itaddr.s_addr == myaddr.s_addr) {
965 * Request/reply to our address, but no lle exists yet.
966 * Calculate full link prepend to use in lle.
968 linkhdrsize = sizeof(linkhdr);
969 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
970 &linkhdrsize, &lladdr_off) != 0)
973 /* Allocate new entry */
974 la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
977 * lle creation may fail if source address belongs
978 * to non-directly connected subnet. However, we
979 * will try to answer the request instead of dropping
984 lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
987 IF_AFDATA_WLOCK(ifp);
989 la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
992 * Check if lle still does not exists.
993 * If it does, that means that we either
994 * 1) have configured it explicitly, via
995 * 1a) 'arp -s' static entry or
996 * 1b) interface address static record
998 * 2) it was the result of sending first packet to-host
1000 * 3) it was another arp reply packet we handled in
1003 * In all cases except 3) we definitely need to prefer
1004 * existing lle. For the sake of simplicity, prefer any
1005 * existing lle over newly-create one.
1008 lltable_link_entry(LLTABLE(ifp), la);
1009 IF_AFDATA_WUNLOCK(ifp);
1011 if (la_tmp == NULL) {
1012 arp_mark_lle_reachable(la);
1015 /* Free newly-create entry and handle packet */
1016 lltable_free_entry(LLTABLE(ifp), la);
1019 arp_check_update_lle(ah, isaddr, ifp, bridged, la);
1020 /* arp_check_update_lle() returns @la unlocked */
1025 if (op != ARPOP_REQUEST)
1027 ARPSTAT_INC(rxrequests);
1029 if (itaddr.s_addr == myaddr.s_addr) {
1030 /* Shortcut.. the receiving interface is the target. */
1031 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1032 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1035 * Destination address is not ours. Check if
1036 * proxyarp entry exists or proxyarp is turned on globally.
1038 struct llentry *lle;
1040 sin.sin_addr = itaddr;
1041 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
1043 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
1044 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1045 (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln);
1051 if (!V_arp_proxyall)
1055 nh = fib4_lookup(ifp->if_fib, itaddr, 0, 0, 0);
1060 * Don't send proxies for nodes on the same interface
1061 * as this one came out of, or we'll get into a fight
1062 * over who claims what Ether address.
1064 if (nh->nh_ifp == ifp)
1067 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
1068 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
1071 * Also check that the node which sent the ARP packet
1072 * is on the interface we expect it to be on. This
1073 * avoids ARP chaos if an interface is connected to the
1077 nh = fib4_lookup(ifp->if_fib, isaddr, 0, 0, 0);
1080 if (nh->nh_ifp != ifp) {
1081 ARP_LOG(LOG_INFO, "proxy: ignoring request"
1082 " from %s via %s\n",
1083 inet_ntoa_r(isaddr, addrbuf),
1089 printf("arp: proxying for %s\n",
1090 inet_ntoa_r(itaddr, addrbuf));
1095 if (itaddr.s_addr == myaddr.s_addr &&
1096 IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
1097 /* RFC 3927 link-local IPv4; always reply by broadcast. */
1098 #ifdef DEBUG_LINKLOCAL
1099 printf("arp: sending reply for link-local addr %s\n",
1100 inet_ntoa_r(itaddr, addrbuf));
1102 m->m_flags |= M_BCAST;
1103 m->m_flags &= ~M_MCAST;
1105 /* default behaviour; never reply by broadcast. */
1106 m->m_flags &= ~(M_BCAST|M_MCAST);
1108 (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
1109 (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
1110 ah->ar_op = htons(ARPOP_REPLY);
1111 ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
1112 m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
1113 m->m_pkthdr.len = m->m_len;
1114 m->m_pkthdr.rcvif = NULL;
1115 sa.sa_family = AF_ARP;
1118 /* Calculate link header for sending frame */
1119 bzero(&ro, sizeof(ro));
1120 linkhdrsize = sizeof(linkhdr);
1121 error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize);
1124 * arp_fillheader() may fail due to lack of support inside encap request
1125 * routing. This is not necessary an error, AF_ARP can/should be handled
1128 if (error != 0 && error != EAFNOSUPPORT) {
1129 ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
1130 if_name(ifp), error);
1134 ro.ro_prepend = linkhdr;
1135 ro.ro_plen = linkhdrsize;
1138 m_clrprotoflags(m); /* Avoid confusing lower layers. */
1139 (*ifp->if_output)(ifp, m, &sa, &ro);
1140 ARPSTAT_INC(txreplies);
1148 static struct mbuf *
1149 arp_grab_holdchain(struct llentry *la)
1153 LLE_WLOCK_ASSERT(la);
1155 chain = la->la_hold;
1163 arp_flush_holdchain(struct ifnet *ifp, struct llentry *la, struct mbuf *chain)
1165 struct mbuf *m_hold, *m_hold_next;
1166 struct sockaddr_in sin;
1171 .ro_prepend = la->r_linkdata,
1172 .ro_plen = la->r_hdrlen,
1175 lltable_fill_sa_entry(la, (struct sockaddr *)&sin);
1177 for (m_hold = chain; m_hold != NULL; m_hold = m_hold_next) {
1178 m_hold_next = m_hold->m_nextpkt;
1179 m_hold->m_nextpkt = NULL;
1180 /* Avoid confusing lower layers. */
1181 m_clrprotoflags(m_hold);
1182 (*ifp->if_output)(ifp, m_hold, (struct sockaddr *)&sin, &ro);
1187 * Checks received arp data against existing @la.
1188 * Updates lle state/performs notification if necessary.
1191 arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp,
1192 int bridged, struct llentry *la)
1194 uint8_t linkhdr[LLE_MAX_LINKHDR];
1197 char addrbuf[INET_ADDRSTRLEN];
1199 LLE_WLOCK_ASSERT(la);
1201 /* the following is not an error when doing bridging */
1202 if (!bridged && la->lle_tbl->llt_ifp != ifp) {
1203 if (log_arp_wrong_iface)
1204 ARP_LOG(LOG_WARNING, "%s is on %s "
1205 "but got reply from %*D on %s\n",
1206 inet_ntoa_r(isaddr, addrbuf),
1207 la->lle_tbl->llt_ifp->if_xname,
1208 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1213 if ((la->la_flags & LLE_VALID) &&
1214 bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) {
1215 if (la->la_flags & LLE_STATIC) {
1217 if (log_arp_permanent_modify)
1219 "%*D attempts to modify "
1220 "permanent entry for %s on %s\n",
1222 (u_char *)ar_sha(ah), ":",
1223 inet_ntoa_r(isaddr, addrbuf),
1227 if (log_arp_movements) {
1228 ARP_LOG(LOG_INFO, "%s moved from %*D "
1230 inet_ntoa_r(isaddr, addrbuf),
1232 (u_char *)la->ll_addr, ":",
1233 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
1238 /* Calculate full link prepend to use in lle */
1239 linkhdrsize = sizeof(linkhdr);
1240 if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr,
1241 &linkhdrsize, &lladdr_off) != 0)
1244 /* Check if something has changed */
1245 if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 ||
1246 (la->la_flags & LLE_VALID) == 0) {
1247 /* Try to perform LLE update */
1248 if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize,
1252 /* Clear fast path feedback request if set */
1253 llentry_mark_used(la);
1256 arp_mark_lle_reachable(la);
1259 * The packets are all freed within the call to the output
1262 * NB: The lock MUST be released before the call to the
1265 if (la->la_hold != NULL) {
1268 chain = arp_grab_holdchain(la);
1270 arp_flush_holdchain(ifp, la, chain);
1276 arp_mark_lle_reachable(struct llentry *la)
1278 int canceled, wtime;
1280 LLE_WLOCK_ASSERT(la);
1282 la->ln_state = ARP_LLINFO_REACHABLE;
1283 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
1285 if (!(la->la_flags & LLE_STATIC)) {
1287 la->la_expire = time_uptime + V_arpt_keep;
1288 wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit;
1290 wtime = V_arpt_keep;
1291 canceled = callout_reset(&la->lle_timer,
1292 hz * wtime, arptimer, la);
1297 la->la_preempt = V_arp_maxtries;
1301 * Add permanent link-layer record for given interface address.
1303 static __noinline void
1304 arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst)
1306 struct llentry *lle, *lle_tmp;
1309 * Interface address LLE record is considered static
1310 * because kernel code relies on LLE_STATIC flag to check
1311 * if these entries can be rewriten by arp updates.
1313 lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst);
1315 log(LOG_INFO, "arp_ifinit: cannot create arp "
1316 "entry for interface address\n");
1320 IF_AFDATA_WLOCK(ifp);
1322 /* Unlink any entry if exists */
1323 lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
1324 if (lle_tmp != NULL)
1325 lltable_unlink_entry(LLTABLE(ifp), lle_tmp);
1327 lltable_link_entry(LLTABLE(ifp), lle);
1328 IF_AFDATA_WUNLOCK(ifp);
1330 if (lle_tmp != NULL)
1331 EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED);
1333 EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED);
1335 if (lle_tmp != NULL)
1336 lltable_free_entry(LLTABLE(ifp), lle_tmp);
1340 * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range
1344 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS)
1347 int rexmit_count = *(int *)arg1;
1349 error = sysctl_handle_int(oidp, &rexmit_count, 0, req);
1351 /* Enforce limits on any new value that may have been set. */
1352 if (!error && req->newptr) {
1353 /* A new value was set. */
1354 if (rexmit_count < 0) {
1356 } else if (rexmit_count > MAX_GARP_RETRANSMITS) {
1357 rexmit_count = MAX_GARP_RETRANSMITS;
1359 *(int *)arg1 = rexmit_count;
1366 * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to
1367 * retransmit it again. A pending callout owns a reference to the ifa.
1370 garp_rexmit(void *arg)
1372 struct in_ifaddr *ia = arg;
1374 if (callout_pending(&ia->ia_garp_timer) ||
1375 !callout_active(&ia->ia_garp_timer)) {
1376 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1377 ifa_free(&ia->ia_ifa);
1381 CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet);
1384 * Drop lock while the ARP request is generated.
1386 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1388 arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr,
1389 &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp));
1392 * Increment the count of retransmissions. If the count has reached the
1393 * maximum value, stop sending the GARP packets. Otherwise, schedule
1394 * the callout to retransmit another GARP packet.
1396 ++ia->ia_garp_count;
1397 if (ia->ia_garp_count >= garp_rexmit_count) {
1398 ifa_free(&ia->ia_ifa);
1401 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1402 rescheduled = callout_reset(&ia->ia_garp_timer,
1403 (1 << ia->ia_garp_count) * hz,
1405 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1407 ifa_free(&ia->ia_ifa);
1415 * Start the GARP retransmit timer.
1417 * A single GARP is always transmitted when an IPv4 address is added
1418 * to an interface and that is usually sufficient. However, in some
1419 * circumstances, such as when a shared address is passed between
1420 * cluster nodes, this single GARP may occasionally be dropped or
1421 * lost. This can lead to neighbors on the network link working with a
1422 * stale ARP cache and sending packets destined for that address to
1423 * the node that previously owned the address, which may not respond.
1425 * To avoid this situation, GARP retransmits can be enabled by setting
1426 * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater
1427 * than zero. The setting represents the maximum number of
1428 * retransmissions. The interval between retransmissions is calculated
1429 * using an exponential backoff algorithm, doubling each time, so the
1430 * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds).
1433 garp_timer_start(struct ifaddr *ifa)
1435 struct in_ifaddr *ia = (struct in_ifaddr *) ifa;
1437 IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp);
1438 ia->ia_garp_count = 0;
1439 if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz,
1440 garp_rexmit, ia) == 0) {
1443 IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp);
1447 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
1449 struct epoch_tracker et;
1450 const struct sockaddr_in *dst_in;
1451 const struct sockaddr *dst;
1453 if (ifa->ifa_carp != NULL)
1456 dst = ifa->ifa_addr;
1457 dst_in = (const struct sockaddr_in *)dst;
1459 if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY)
1461 NET_EPOCH_ENTER(et);
1462 arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp));
1464 if (garp_rexmit_count > 0) {
1465 garp_timer_start(ifa);
1468 arp_add_ifa_lle(ifp, dst);
1472 arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr)
1475 if (ntohl(addr.s_addr) != INADDR_ANY)
1476 arprequest(ifp, &addr, &addr, enaddr);
1480 * Sends gratuitous ARPs for each ifaddr to notify other
1481 * nodes about the address change.
1483 static __noinline void
1484 arp_handle_ifllchange(struct ifnet *ifp)
1488 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
1489 if (ifa->ifa_addr->sa_family == AF_INET)
1490 arp_ifinit(ifp, ifa);
1495 * A handler for interface link layer address change event.
1498 arp_iflladdr(void *arg __unused, struct ifnet *ifp)
1500 /* if_bridge can update its lladdr during if_vmove(), after we've done
1501 * if_detach_internal()/dom_ifdetach(). */
1502 if (ifp->if_afdata[AF_INET] == NULL)
1505 lltable_update_ifaddr(LLTABLE(ifp));
1507 if ((ifp->if_flags & IFF_UP) != 0)
1508 arp_handle_ifllchange(ifp);
1515 if (IS_DEFAULT_VNET(curvnet)) {
1516 netisr_register(&arp_nh);
1517 iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event,
1518 arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY);
1522 netisr_register_vnet(&arp_nh);
1525 VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND,
1530 * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH
1531 * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5.
1534 vnet_arp_destroy(__unused void *arg)
1537 netisr_unregister_vnet(&arp_nh);
1539 VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1540 vnet_arp_destroy, NULL);