/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1982, 1986, 1988, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)if_ether.c 8.1 (Berkeley) 6/10/93 */ /* * Ethernet address resolution protocol. * TODO: * add "inuse/lock" bit (or ref. count) along with valid bit */ #include __FBSDID("$FreeBSD$"); #include "opt_inet.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET #include #endif #include #define SIN(s) ((const struct sockaddr_in *)(s)) static struct timeval arp_lastlog; static int arp_curpps; static int arp_maxpps = 1; /* Simple ARP state machine */ enum arp_llinfo_state { ARP_LLINFO_INCOMPLETE = 0, /* No LLE data */ ARP_LLINFO_REACHABLE, /* LLE is valid */ ARP_LLINFO_VERIFY, /* LLE is valid, need refresh */ ARP_LLINFO_DELETED, /* LLE is deleted */ }; SYSCTL_DECL(_net_link_ether); static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, ""); static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, ""); /* timer values */ static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20 * minutes */ static VNET_DEFINE(int, arp_maxtries) = 5; static VNET_DEFINE(int, arp_proxyall) = 0; static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for * 20 seconds */ static VNET_DEFINE(int, arpt_rexmit) = 1; /* retransmit arp entries, sec*/ VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat); /* ARP statistics, see if_arp.h */ VNET_PCPUSTAT_SYSINIT(arpstat); #ifdef VIMAGE VNET_PCPUSTAT_SYSUNINIT(arpstat); #endif /* VIMAGE */ static VNET_DEFINE(int, arp_maxhold) = 1; #define V_arpt_keep VNET(arpt_keep) #define V_arpt_down VNET(arpt_down) #define V_arpt_rexmit VNET(arpt_rexmit) #define V_arp_maxtries VNET(arp_maxtries) #define V_arp_proxyall VNET(arp_proxyall) #define V_arp_maxhold VNET(arp_maxhold) SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(arpt_keep), 0, "ARP entry lifetime in seconds"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(arp_maxtries), 0, "ARP resolution attempts before returning error"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(arp_proxyall), 0, "Enable proxy ARP for all suitable requests"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(arpt_down), 0, "Incomplete ARP entry lifetime in seconds"); SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat, arpstat, "ARP statistics (struct arpstat, net/if_arp.h)"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(arp_maxhold), 0, "Number of packets to hold per ARP entry"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second, CTLFLAG_RW, &arp_maxpps, 0, "Maximum number of remotely triggered ARP messages that can be " "logged per second"); /* * Due to the exponential backoff algorithm used for the interval between GARP * retransmissions, the maximum number of retransmissions is limited for * sanity. This limit corresponds to a maximum interval between retransmissions * of 2^16 seconds ~= 18 hours. * * Making this limit more dynamic is more complicated than worthwhile, * especially since sending out GARPs spaced days apart would be of little * use. A maximum dynamic limit would look something like: * * const int max = fls(INT_MAX / hz) - 1; */ #define MAX_GARP_RETRANSMITS 16 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS); static int garp_rexmit_count = 0; /* GARP retransmission setting. */ SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count, CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE, &garp_rexmit_count, 0, sysctl_garp_rexmit, "I", "Number of times to retransmit GARP packets;" " 0 to disable, maximum of 16"); #define ARP_LOG(pri, ...) do { \ if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \ log((pri), "arp: " __VA_ARGS__); \ } while (0) static void arpintr(struct mbuf *); static void arptimer(void *); #ifdef INET static void in_arpinput(struct mbuf *); #endif static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, int bridged, struct llentry *la); static void arp_mark_lle_reachable(struct llentry *la); static void arp_iflladdr(void *arg __unused, struct ifnet *ifp); static eventhandler_tag iflladdr_tag; static const struct netisr_handler arp_nh = { .nh_name = "arp", .nh_handler = arpintr, .nh_proto = NETISR_ARP, .nh_policy = NETISR_POLICY_SOURCE, }; /* * Timeout routine. Age arp_tab entries periodically. */ static void arptimer(void *arg) { struct llentry *lle = (struct llentry *)arg; struct ifnet *ifp; int r_skip_req; if (lle->la_flags & LLE_STATIC) { return; } LLE_WLOCK(lle); if (callout_pending(&lle->lle_timer)) { /* * Here we are a bit odd here in the treatment of * active/pending. If the pending bit is set, it got * rescheduled before I ran. The active * bit we ignore, since if it was stopped * in ll_tablefree() and was currently running * it would have return 0 so the code would * not have deleted it since the callout could * not be stopped so we want to go through * with the delete here now. If the callout * was restarted, the pending bit will be back on and * we just want to bail since the callout_reset would * return 1 and our reference would have been removed * by arpresolve() below. */ LLE_WUNLOCK(lle); return; } ifp = lle->lle_tbl->llt_ifp; CURVNET_SET(ifp->if_vnet); switch (lle->ln_state) { case ARP_LLINFO_REACHABLE: /* * Expiration time is approaching. * Let's try to refresh entry if it is still * in use. * * Set r_skip_req to get feedback from * fast path. Change state and re-schedule * ourselves. */ LLE_REQ_LOCK(lle); lle->r_skip_req = 1; LLE_REQ_UNLOCK(lle); lle->ln_state = ARP_LLINFO_VERIFY; callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); LLE_WUNLOCK(lle); CURVNET_RESTORE(); return; case ARP_LLINFO_VERIFY: LLE_REQ_LOCK(lle); r_skip_req = lle->r_skip_req; LLE_REQ_UNLOCK(lle); if (r_skip_req == 0 && lle->la_preempt > 0) { /* Entry was used, issue refresh request */ struct in_addr dst; dst = lle->r_l3addr.addr4; lle->la_preempt--; callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); LLE_WUNLOCK(lle); arprequest(ifp, NULL, &dst, NULL); CURVNET_RESTORE(); return; } /* Nothing happened. Reschedule if not too late */ if (lle->la_expire > time_uptime) { callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit); LLE_WUNLOCK(lle); CURVNET_RESTORE(); return; } break; case ARP_LLINFO_INCOMPLETE: case ARP_LLINFO_DELETED: break; } if ((lle->la_flags & LLE_DELETED) == 0) { int evt; if (lle->la_flags & LLE_VALID) evt = LLENTRY_EXPIRED; else evt = LLENTRY_TIMEDOUT; EVENTHANDLER_INVOKE(lle_event, lle, evt); } callout_stop(&lle->lle_timer); /* XXX: LOR avoidance. We still have ref on lle. */ LLE_WUNLOCK(lle); IF_AFDATA_LOCK(ifp); LLE_WLOCK(lle); /* Guard against race with other llentry_free(). */ if (lle->la_flags & LLE_LINKED) { LLE_REMREF(lle); lltable_unlink_entry(lle->lle_tbl, lle); } IF_AFDATA_UNLOCK(ifp); size_t pkts_dropped = llentry_free(lle); ARPSTAT_ADD(dropped, pkts_dropped); ARPSTAT_INC(timeouts); CURVNET_RESTORE(); } /* * Stores link-layer header for @ifp in format suitable for if_output() * into buffer @buf. Resulting header length is stored in @bufsize. * * Returns 0 on success. */ static int arp_fillheader(struct ifnet *ifp, struct arphdr *ah, int bcast, u_char *buf, size_t *bufsize) { struct if_encap_req ereq; int error; bzero(buf, *bufsize); bzero(&ereq, sizeof(ereq)); ereq.buf = buf; ereq.bufsize = *bufsize; ereq.rtype = IFENCAP_LL; ereq.family = AF_ARP; ereq.lladdr = ar_tha(ah); ereq.hdata = (u_char *)ah; if (bcast) ereq.flags = IFENCAP_FLAG_BROADCAST; error = ifp->if_requestencap(ifp, &ereq); if (error == 0) *bufsize = ereq.bufsize; return (error); } /* * Broadcast an ARP request. Caller specifies: * - arp header source ip address * - arp header target ip address * - arp header source ethernet address */ void arprequest(struct ifnet *ifp, const struct in_addr *sip, const struct in_addr *tip, u_char *enaddr) { struct mbuf *m; struct arphdr *ah; struct sockaddr sa; u_char *carpaddr = NULL; uint8_t linkhdr[LLE_MAX_LINKHDR]; size_t linkhdrsize; struct route ro; int error; if (sip == NULL) { /* * The caller did not supply a source address, try to find * a compatible one among those assigned to this interface. */ struct ifaddr *ifa; IF_ADDR_RLOCK(ifp); TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { if (ifa->ifa_addr->sa_family != AF_INET) continue; if (ifa->ifa_carp) { if ((*carp_iamatch_p)(ifa, &carpaddr) == 0) continue; sip = &IA_SIN(ifa)->sin_addr; } else { carpaddr = NULL; sip = &IA_SIN(ifa)->sin_addr; } if (0 == ((sip->s_addr ^ tip->s_addr) & IA_MASKSIN(ifa)->sin_addr.s_addr)) break; /* found it. */ } IF_ADDR_RUNLOCK(ifp); if (sip == NULL) { printf("%s: cannot find matching address\n", __func__); return; } } if (enaddr == NULL) enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp); if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL) return; m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) + 2 * ifp->if_addrlen; m->m_pkthdr.len = m->m_len; M_ALIGN(m, m->m_len); ah = mtod(m, struct arphdr *); bzero((caddr_t)ah, m->m_len); #ifdef MAC mac_netinet_arp_send(ifp, m); #endif ah->ar_pro = htons(ETHERTYPE_IP); ah->ar_hln = ifp->if_addrlen; /* hardware address length */ ah->ar_pln = sizeof(struct in_addr); /* protocol address length */ ah->ar_op = htons(ARPOP_REQUEST); bcopy(enaddr, ar_sha(ah), ah->ar_hln); bcopy(sip, ar_spa(ah), ah->ar_pln); bcopy(tip, ar_tpa(ah), ah->ar_pln); sa.sa_family = AF_ARP; sa.sa_len = 2; /* Calculate link header for sending frame */ bzero(&ro, sizeof(ro)); linkhdrsize = sizeof(linkhdr); error = arp_fillheader(ifp, ah, 1, linkhdr, &linkhdrsize); if (error != 0 && error != EAFNOSUPPORT) { ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", if_name(ifp), error); return; } ro.ro_prepend = linkhdr; ro.ro_plen = linkhdrsize; ro.ro_flags = 0; m->m_flags |= M_BCAST; m_clrprotoflags(m); /* Avoid confusing lower layers. */ (*ifp->if_output)(ifp, m, &sa, &ro); ARPSTAT_INC(txrequests); } /* * Resolve an IP address into an ethernet address - heavy version. * Used internally by arpresolve(). * We have already checked than we can't use existing lle without * modification so we have to acquire LLE_EXCLUSIVE lle lock. * * On success, desten and flags are filled in and the function returns 0; * If the packet must be held pending resolution, we return EWOULDBLOCK * On other errors, we return the corresponding error code. * Note that m_freem() handles NULL. */ static int arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m, const struct sockaddr *dst, u_char *desten, uint32_t *pflags, struct llentry **plle) { struct llentry *la = NULL, *la_tmp; struct mbuf *curr = NULL; struct mbuf *next = NULL; int error, renew; char *lladdr; int ll_len; if (pflags != NULL) *pflags = 0; if (plle != NULL) *plle = NULL; if ((flags & LLE_CREATE) == 0) { IF_AFDATA_RLOCK(ifp); la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); IF_AFDATA_RUNLOCK(ifp); } if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) { la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); if (la == NULL) { char addrbuf[INET_ADDRSTRLEN]; log(LOG_DEBUG, "arpresolve: can't allocate llinfo for %s on %s\n", inet_ntoa_r(SIN(dst)->sin_addr, addrbuf), if_name(ifp)); m_freem(m); return (EINVAL); } IF_AFDATA_WLOCK(ifp); LLE_WLOCK(la); la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); /* Prefer ANY existing lle over newly-created one */ if (la_tmp == NULL) lltable_link_entry(LLTABLE(ifp), la); IF_AFDATA_WUNLOCK(ifp); if (la_tmp != NULL) { lltable_free_entry(LLTABLE(ifp), la); la = la_tmp; } } if (la == NULL) { m_freem(m); return (EINVAL); } if ((la->la_flags & LLE_VALID) && ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) { if (flags & LLE_ADDRONLY) { lladdr = la->ll_addr; ll_len = ifp->if_addrlen; } else { lladdr = la->r_linkdata; ll_len = la->r_hdrlen; } bcopy(lladdr, desten, ll_len); /* Notify LLE code that the entry was used by datapath */ llentry_mark_used(la); if (pflags != NULL) *pflags = la->la_flags & (LLE_VALID|LLE_IFADDR); if (plle) { LLE_ADDREF(la); *plle = la; } LLE_WUNLOCK(la); return (0); } renew = (la->la_asked == 0 || la->la_expire != time_uptime); /* * There is an arptab entry, but no ethernet address * response yet. Add the mbuf to the list, dropping * the oldest packet if we have exceeded the system * setting. */ if (m != NULL) { if (la->la_numheld >= V_arp_maxhold) { if (la->la_hold != NULL) { next = la->la_hold->m_nextpkt; m_freem(la->la_hold); la->la_hold = next; la->la_numheld--; ARPSTAT_INC(dropped); } } if (la->la_hold != NULL) { curr = la->la_hold; while (curr->m_nextpkt != NULL) curr = curr->m_nextpkt; curr->m_nextpkt = m; } else la->la_hold = m; la->la_numheld++; } /* * Return EWOULDBLOCK if we have tried less than arp_maxtries. It * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH * if we have already sent arp_maxtries ARP requests. Retransmit the * ARP request, but not faster than one request per second. */ if (la->la_asked < V_arp_maxtries) error = EWOULDBLOCK; /* First request. */ else error = is_gw != 0 ? EHOSTUNREACH : EHOSTDOWN; if (renew) { int canceled; LLE_ADDREF(la); la->la_expire = time_uptime; canceled = callout_reset(&la->lle_timer, hz * V_arpt_down, arptimer, la); if (canceled) LLE_REMREF(la); la->la_asked++; LLE_WUNLOCK(la); arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL); return (error); } LLE_WUNLOCK(la); return (error); } /* * Resolve an IP address into an ethernet address. */ int arpresolve_addr(struct ifnet *ifp, int flags, const struct sockaddr *dst, char *desten, uint32_t *pflags, struct llentry **plle) { int error; flags |= LLE_ADDRONLY; error = arpresolve_full(ifp, 0, flags, NULL, dst, desten, pflags, plle); return (error); } /* * Lookups link header based on an IP address. * On input: * ifp is the interface we use * is_gw != 0 if @dst represents gateway to some destination * m is the mbuf. May be NULL if we don't have a packet. * dst is the next hop, * desten is the storage to put LL header. * flags returns subset of lle flags: LLE_VALID | LLE_IFADDR * * On success, full/partial link header and flags are filled in and * the function returns 0. * If the packet must be held pending resolution, we return EWOULDBLOCK * On other errors, we return the corresponding error code. * Note that m_freem() handles NULL. */ int arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m, const struct sockaddr *dst, u_char *desten, uint32_t *pflags, struct llentry **plle) { struct llentry *la = NULL; if (pflags != NULL) *pflags = 0; if (plle != NULL) *plle = NULL; if (m != NULL) { if (m->m_flags & M_BCAST) { /* broadcast */ (void)memcpy(desten, ifp->if_broadcastaddr, ifp->if_addrlen); return (0); } if (m->m_flags & M_MCAST) { /* multicast */ ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); return (0); } } IF_AFDATA_RLOCK(ifp); la = lla_lookup(LLTABLE(ifp), plle ? LLE_EXCLUSIVE : LLE_UNLOCKED, dst); if (la != NULL && (la->r_flags & RLLE_VALID) != 0) { /* Entry found, let's copy lle info */ bcopy(la->r_linkdata, desten, la->r_hdrlen); if (pflags != NULL) *pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR); /* Notify the LLE handling code that the entry was used. */ llentry_mark_used(la); if (plle) { LLE_ADDREF(la); *plle = la; LLE_WUNLOCK(la); } IF_AFDATA_RUNLOCK(ifp); return (0); } if (plle && la) LLE_WUNLOCK(la); IF_AFDATA_RUNLOCK(ifp); return (arpresolve_full(ifp, is_gw, la == NULL ? LLE_CREATE : 0, m, dst, desten, pflags, plle)); } /* * Common length and type checks are done here, * then the protocol-specific routine is called. */ static void arpintr(struct mbuf *m) { struct arphdr *ar; struct ifnet *ifp; char *layer; int hlen; ifp = m->m_pkthdr.rcvif; if (m->m_len < sizeof(struct arphdr) && ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { ARP_LOG(LOG_NOTICE, "packet with short header received on %s\n", if_name(ifp)); return; } ar = mtod(m, struct arphdr *); /* Check if length is sufficient */ if (m->m_len < arphdr_len(ar)) { m = m_pullup(m, arphdr_len(ar)); if (m == NULL) { ARP_LOG(LOG_NOTICE, "short packet received on %s\n", if_name(ifp)); return; } ar = mtod(m, struct arphdr *); } hlen = 0; layer = ""; switch (ntohs(ar->ar_hrd)) { case ARPHRD_ETHER: hlen = ETHER_ADDR_LEN; /* RFC 826 */ layer = "ethernet"; break; case ARPHRD_IEEE802: hlen = 6; /* RFC 1390, FDDI_ADDR_LEN */ layer = "fddi"; break; case ARPHRD_ARCNET: hlen = 1; /* RFC 1201, ARC_ADDR_LEN */ layer = "arcnet"; break; case ARPHRD_INFINIBAND: hlen = 20; /* RFC 4391, INFINIBAND_ALEN */ layer = "infiniband"; break; case ARPHRD_IEEE1394: hlen = 0; /* SHALL be 16 */ /* RFC 2734 */ layer = "firewire"; /* * Restrict too long hardware addresses. * Currently we are capable of handling 20-byte * addresses ( sizeof(lle->ll_addr) ) */ if (ar->ar_hln >= 20) hlen = 16; break; default: ARP_LOG(LOG_NOTICE, "packet with unknown hardware format 0x%02d received on " "%s\n", ntohs(ar->ar_hrd), if_name(ifp)); m_freem(m); return; } if (hlen != 0 && hlen != ar->ar_hln) { ARP_LOG(LOG_NOTICE, "packet with invalid %s address length %d received on %s\n", layer, ar->ar_hln, if_name(ifp)); m_freem(m); return; } ARPSTAT_INC(received); switch (ntohs(ar->ar_pro)) { #ifdef INET case ETHERTYPE_IP: in_arpinput(m); return; #endif } m_freem(m); } #ifdef INET /* * ARP for Internet protocols on 10 Mb/s Ethernet. * Algorithm is that given in RFC 826. * In addition, a sanity check is performed on the sender * protocol address, to catch impersonators. * We no longer handle negotiations for use of trailer protocol: * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent * along with IP replies if we wanted trailers sent to us, * and also sent them in response to IP replies. * This allowed either end to announce the desire to receive * trailer packets. * We no longer reply to requests for ETHERTYPE_TRAIL protocol either, * but formerly didn't normally send requests. */ static int log_arp_wrong_iface = 1; static int log_arp_movements = 1; static int log_arp_permanent_modify = 1; static int allow_multicast = 0; SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, &log_arp_wrong_iface, 0, "log arp packets arriving on the wrong interface"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, &log_arp_movements, 0, "log arp replies from MACs different than the one in the cache"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, &log_arp_permanent_modify, 0, "log arp replies from MACs different than the one in the permanent arp entry"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, &allow_multicast, 0, "accept multicast addresses"); static void in_arpinput(struct mbuf *m) { struct rm_priotracker in_ifa_tracker; struct arphdr *ah; struct ifnet *ifp = m->m_pkthdr.rcvif; struct llentry *la = NULL, *la_tmp; struct ifaddr *ifa; struct in_ifaddr *ia; struct sockaddr sa; struct in_addr isaddr, itaddr, myaddr; u_int8_t *enaddr = NULL; int op; int bridged = 0, is_bridge = 0; int carped; struct sockaddr_in sin; struct sockaddr *dst; struct nhop4_basic nh4; uint8_t linkhdr[LLE_MAX_LINKHDR]; struct route ro; size_t linkhdrsize; int lladdr_off; int error; char addrbuf[INET_ADDRSTRLEN]; sin.sin_len = sizeof(struct sockaddr_in); sin.sin_family = AF_INET; sin.sin_addr.s_addr = 0; if (ifp->if_bridge) bridged = 1; if (ifp->if_type == IFT_BRIDGE) is_bridge = 1; /* * We already have checked that mbuf contains enough contiguous data * to hold entire arp message according to the arp header. */ ah = mtod(m, struct arphdr *); /* * ARP is only for IPv4 so we can reject packets with * a protocol length not equal to an IPv4 address. */ if (ah->ar_pln != sizeof(struct in_addr)) { ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n", sizeof(struct in_addr)); goto drop; } if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { ARP_LOG(LOG_NOTICE, "%*D is multicast\n", ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); goto drop; } op = ntohs(ah->ar_op); (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); if (op == ARPOP_REPLY) ARPSTAT_INC(rxreplies); /* * For a bridge, we want to check the address irrespective * of the receive interface. (This will change slightly * when we have clusters of interfaces). */ IN_IFADDR_RLOCK(&in_ifa_tracker); LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || ia->ia_ifp == ifp) && itaddr.s_addr == ia->ia_addr.sin_addr.s_addr && (ia->ia_ifa.ifa_carp == NULL || (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) { ifa_ref(&ia->ia_ifa); IN_IFADDR_RUNLOCK(&in_ifa_tracker); goto match; } } LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) || ia->ia_ifp == ifp) && isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { ifa_ref(&ia->ia_ifa); IN_IFADDR_RUNLOCK(&in_ifa_tracker); goto match; } #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia) \ (ia->ia_ifp->if_bridge == ifp->if_softc && \ !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) && \ addr == ia->ia_addr.sin_addr.s_addr) /* * Check the case when bridge shares its MAC address with * some of its children, so packets are claimed by bridge * itself (bridge_input() does it first), but they are really * meant to be destined to the bridge member. */ if (is_bridge) { LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) { ifa_ref(&ia->ia_ifa); ifp = ia->ia_ifp; IN_IFADDR_RUNLOCK(&in_ifa_tracker); goto match; } } } #undef BDG_MEMBER_MATCHES_ARP IN_IFADDR_RUNLOCK(&in_ifa_tracker); /* * No match, use the first inet address on the receive interface * as a dummy address for the rest of the function. */ IF_ADDR_RLOCK(ifp); TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) if (ifa->ifa_addr->sa_family == AF_INET && (ifa->ifa_carp == NULL || (*carp_iamatch_p)(ifa, &enaddr))) { ia = ifatoia(ifa); ifa_ref(ifa); IF_ADDR_RUNLOCK(ifp); goto match; } IF_ADDR_RUNLOCK(ifp); /* * If bridging, fall back to using any inet address. */ IN_IFADDR_RLOCK(&in_ifa_tracker); if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) { IN_IFADDR_RUNLOCK(&in_ifa_tracker); goto drop; } ifa_ref(&ia->ia_ifa); IN_IFADDR_RUNLOCK(&in_ifa_tracker); match: if (!enaddr) enaddr = (u_int8_t *)IF_LLADDR(ifp); carped = (ia->ia_ifa.ifa_carp != NULL); myaddr = ia->ia_addr.sin_addr; ifa_free(&ia->ia_ifa); if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) goto drop; /* it's from me, ignore it. */ if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address " "%s!\n", inet_ntoa_r(isaddr, addrbuf)); goto drop; } if (ifp->if_addrlen != ah->ar_hln) { ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, " "i/f %d (ignored)\n", ifp->if_addrlen, (u_char *) ar_sha(ah), ":", ah->ar_hln, ifp->if_addrlen); goto drop; } /* * Warn if another host is using the same IP address, but only if the * IP address isn't 0.0.0.0, which is used for DHCP only, in which * case we suppress the warning to avoid false positive complaints of * potential misconfiguration. */ if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n", ifp->if_addrlen, (u_char *)ar_sha(ah), ":", inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); itaddr = myaddr; ARPSTAT_INC(dupips); goto reply; } if (ifp->if_flags & IFF_STATICARP) goto reply; bzero(&sin, sizeof(sin)); sin.sin_len = sizeof(struct sockaddr_in); sin.sin_family = AF_INET; sin.sin_addr = isaddr; dst = (struct sockaddr *)&sin; IF_AFDATA_RLOCK(ifp); la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); IF_AFDATA_RUNLOCK(ifp); if (la != NULL) arp_check_update_lle(ah, isaddr, ifp, bridged, la); else if (itaddr.s_addr == myaddr.s_addr) { /* * Request/reply to our address, but no lle exists yet. * Calculate full link prepend to use in lle. */ linkhdrsize = sizeof(linkhdr); if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, &linkhdrsize, &lladdr_off) != 0) goto reply; /* Allocate new entry */ la = lltable_alloc_entry(LLTABLE(ifp), 0, dst); if (la == NULL) { /* * lle creation may fail if source address belongs * to non-directly connected subnet. However, we * will try to answer the request instead of dropping * frame. */ goto reply; } lltable_set_entry_addr(ifp, la, linkhdr, linkhdrsize, lladdr_off); IF_AFDATA_WLOCK(ifp); LLE_WLOCK(la); la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); /* * Check if lle still does not exists. * If it does, that means that we either * 1) have configured it explicitly, via * 1a) 'arp -s' static entry or * 1b) interface address static record * or * 2) it was the result of sending first packet to-host * or * 3) it was another arp reply packet we handled in * different thread. * * In all cases except 3) we definitely need to prefer * existing lle. For the sake of simplicity, prefer any * existing lle over newly-create one. */ if (la_tmp == NULL) lltable_link_entry(LLTABLE(ifp), la); IF_AFDATA_WUNLOCK(ifp); if (la_tmp == NULL) { arp_mark_lle_reachable(la); LLE_WUNLOCK(la); } else { /* Free newly-create entry and handle packet */ lltable_free_entry(LLTABLE(ifp), la); la = la_tmp; la_tmp = NULL; arp_check_update_lle(ah, isaddr, ifp, bridged, la); /* arp_check_update_lle() returns @la unlocked */ } la = NULL; } reply: if (op != ARPOP_REQUEST) goto drop; ARPSTAT_INC(rxrequests); if (itaddr.s_addr == myaddr.s_addr) { /* Shortcut.. the receiving interface is the target. */ (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); } else { struct llentry *lle = NULL; sin.sin_addr = itaddr; IF_AFDATA_RLOCK(ifp); lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin); IF_AFDATA_RUNLOCK(ifp); if ((lle != NULL) && (lle->la_flags & LLE_PUB)) { (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); (void)memcpy(ar_sha(ah), lle->ll_addr, ah->ar_hln); LLE_RUNLOCK(lle); } else { if (lle != NULL) LLE_RUNLOCK(lle); if (!V_arp_proxyall) goto drop; /* XXX MRT use table 0 for arp reply */ if (fib4_lookup_nh_basic(0, itaddr, 0, 0, &nh4) != 0) goto drop; /* * Don't send proxies for nodes on the same interface * as this one came out of, or we'll get into a fight * over who claims what Ether address. */ if (nh4.nh_ifp == ifp) goto drop; (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); /* * Also check that the node which sent the ARP packet * is on the interface we expect it to be on. This * avoids ARP chaos if an interface is connected to the * wrong network. */ /* XXX MRT use table 0 for arp checks */ if (fib4_lookup_nh_basic(0, isaddr, 0, 0, &nh4) != 0) goto drop; if (nh4.nh_ifp != ifp) { ARP_LOG(LOG_INFO, "proxy: ignoring request" " from %s via %s\n", inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); goto drop; } #ifdef DEBUG_PROXY printf("arp: proxying for %s\n", inet_ntoa_r(itaddr, addrbuf)); #endif } } if (itaddr.s_addr == myaddr.s_addr && IN_LINKLOCAL(ntohl(itaddr.s_addr))) { /* RFC 3927 link-local IPv4; always reply by broadcast. */ #ifdef DEBUG_LINKLOCAL printf("arp: sending reply for link-local addr %s\n", inet_ntoa_r(itaddr, addrbuf)); #endif m->m_flags |= M_BCAST; m->m_flags &= ~M_MCAST; } else { /* default behaviour; never reply by broadcast. */ m->m_flags &= ~(M_BCAST|M_MCAST); } (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); ah->ar_op = htons(ARPOP_REPLY); ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); m->m_pkthdr.len = m->m_len; m->m_pkthdr.rcvif = NULL; sa.sa_family = AF_ARP; sa.sa_len = 2; /* Calculate link header for sending frame */ bzero(&ro, sizeof(ro)); linkhdrsize = sizeof(linkhdr); error = arp_fillheader(ifp, ah, 0, linkhdr, &linkhdrsize); /* * arp_fillheader() may fail due to lack of support inside encap request * routing. This is not necessary an error, AF_ARP can/should be handled * by if_output(). */ if (error != 0 && error != EAFNOSUPPORT) { ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n", if_name(ifp), error); return; } ro.ro_prepend = linkhdr; ro.ro_plen = linkhdrsize; ro.ro_flags = 0; m_clrprotoflags(m); /* Avoid confusing lower layers. */ (*ifp->if_output)(ifp, m, &sa, &ro); ARPSTAT_INC(txreplies); return; drop: m_freem(m); } #endif /* * Checks received arp data against existing @la. * Updates lle state/performs notification if necessary. */ static void arp_check_update_lle(struct arphdr *ah, struct in_addr isaddr, struct ifnet *ifp, int bridged, struct llentry *la) { struct sockaddr sa; struct mbuf *m_hold, *m_hold_next; uint8_t linkhdr[LLE_MAX_LINKHDR]; size_t linkhdrsize; int lladdr_off; char addrbuf[INET_ADDRSTRLEN]; LLE_WLOCK_ASSERT(la); /* the following is not an error when doing bridging */ if (!bridged && la->lle_tbl->llt_ifp != ifp) { if (log_arp_wrong_iface) ARP_LOG(LOG_WARNING, "%s is on %s " "but got reply from %*D on %s\n", inet_ntoa_r(isaddr, addrbuf), la->lle_tbl->llt_ifp->if_xname, ifp->if_addrlen, (u_char *)ar_sha(ah), ":", ifp->if_xname); LLE_WUNLOCK(la); return; } if ((la->la_flags & LLE_VALID) && bcmp(ar_sha(ah), la->ll_addr, ifp->if_addrlen)) { if (la->la_flags & LLE_STATIC) { LLE_WUNLOCK(la); if (log_arp_permanent_modify) ARP_LOG(LOG_ERR, "%*D attempts to modify " "permanent entry for %s on %s\n", ifp->if_addrlen, (u_char *)ar_sha(ah), ":", inet_ntoa_r(isaddr, addrbuf), ifp->if_xname); return; } if (log_arp_movements) { ARP_LOG(LOG_INFO, "%s moved from %*D " "to %*D on %s\n", inet_ntoa_r(isaddr, addrbuf), ifp->if_addrlen, (u_char *)la->ll_addr, ":", ifp->if_addrlen, (u_char *)ar_sha(ah), ":", ifp->if_xname); } } /* Calculate full link prepend to use in lle */ linkhdrsize = sizeof(linkhdr); if (lltable_calc_llheader(ifp, AF_INET, ar_sha(ah), linkhdr, &linkhdrsize, &lladdr_off) != 0) return; /* Check if something has changed */ if (memcmp(la->r_linkdata, linkhdr, linkhdrsize) != 0 || (la->la_flags & LLE_VALID) == 0) { /* Try to perform LLE update */ if (lltable_try_set_entry_addr(ifp, la, linkhdr, linkhdrsize, lladdr_off) == 0) return; /* Clear fast path feedback request if set */ la->r_skip_req = 0; } arp_mark_lle_reachable(la); /* * The packets are all freed within the call to the output * routine. * * NB: The lock MUST be released before the call to the * output routine. */ if (la->la_hold != NULL) { m_hold = la->la_hold; la->la_hold = NULL; la->la_numheld = 0; lltable_fill_sa_entry(la, &sa); LLE_WUNLOCK(la); for (; m_hold != NULL; m_hold = m_hold_next) { m_hold_next = m_hold->m_nextpkt; m_hold->m_nextpkt = NULL; /* Avoid confusing lower layers. */ m_clrprotoflags(m_hold); (*ifp->if_output)(ifp, m_hold, &sa, NULL); } } else LLE_WUNLOCK(la); } static void arp_mark_lle_reachable(struct llentry *la) { int canceled, wtime; LLE_WLOCK_ASSERT(la); la->ln_state = ARP_LLINFO_REACHABLE; EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED); if (!(la->la_flags & LLE_STATIC)) { LLE_ADDREF(la); la->la_expire = time_uptime + V_arpt_keep; wtime = V_arpt_keep - V_arp_maxtries * V_arpt_rexmit; if (wtime < 0) wtime = V_arpt_keep; canceled = callout_reset(&la->lle_timer, hz * wtime, arptimer, la); if (canceled) LLE_REMREF(la); } la->la_asked = 0; la->la_preempt = V_arp_maxtries; } /* * Add permanent link-layer record for given interface address. */ static __noinline void arp_add_ifa_lle(struct ifnet *ifp, const struct sockaddr *dst) { struct llentry *lle, *lle_tmp; /* * Interface address LLE record is considered static * because kernel code relies on LLE_STATIC flag to check * if these entries can be rewriten by arp updates. */ lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, dst); if (lle == NULL) { log(LOG_INFO, "arp_ifinit: cannot create arp " "entry for interface address\n"); return; } IF_AFDATA_WLOCK(ifp); LLE_WLOCK(lle); /* Unlink any entry if exists */ lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst); if (lle_tmp != NULL) lltable_unlink_entry(LLTABLE(ifp), lle_tmp); lltable_link_entry(LLTABLE(ifp), lle); IF_AFDATA_WUNLOCK(ifp); if (lle_tmp != NULL) EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED); EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED); LLE_WUNLOCK(lle); if (lle_tmp != NULL) lltable_free_entry(LLTABLE(ifp), lle_tmp); } /* * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range * of valid values. */ static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS) { int error; int rexmit_count = *(int *)arg1; error = sysctl_handle_int(oidp, &rexmit_count, 0, req); /* Enforce limits on any new value that may have been set. */ if (!error && req->newptr) { /* A new value was set. */ if (rexmit_count < 0) { rexmit_count = 0; } else if (rexmit_count > MAX_GARP_RETRANSMITS) { rexmit_count = MAX_GARP_RETRANSMITS; } *(int *)arg1 = rexmit_count; } return (error); } /* * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to * retransmit it again. A pending callout owns a reference to the ifa. */ static void garp_rexmit(void *arg) { struct in_ifaddr *ia = arg; if (callout_pending(&ia->ia_garp_timer) || !callout_active(&ia->ia_garp_timer)) { IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); ifa_free(&ia->ia_ifa); return; } /* * Drop lock while the ARP request is generated. */ IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr, &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp)); /* * Increment the count of retransmissions. If the count has reached the * maximum value, stop sending the GARP packets. Otherwise, schedule * the callout to retransmit another GARP packet. */ ++ia->ia_garp_count; if (ia->ia_garp_count >= garp_rexmit_count) { ifa_free(&ia->ia_ifa); } else { int rescheduled; IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); rescheduled = callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, garp_rexmit, ia); IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); if (rescheduled) { ifa_free(&ia->ia_ifa); } } } /* * Start the GARP retransmit timer. * * A single GARP is always transmitted when an IPv4 address is added * to an interface and that is usually sufficient. However, in some * circumstances, such as when a shared address is passed between * cluster nodes, this single GARP may occasionally be dropped or * lost. This can lead to neighbors on the network link working with a * stale ARP cache and sending packets destined for that address to * the node that previously owned the address, which may not respond. * * To avoid this situation, GARP retransmits can be enabled by setting * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater * than zero. The setting represents the maximum number of * retransmissions. The interval between retransmissions is calculated * using an exponential backoff algorithm, doubling each time, so the * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). */ static void garp_timer_start(struct ifaddr *ifa) { struct in_ifaddr *ia = (struct in_ifaddr *) ifa; IF_ADDR_WLOCK(ia->ia_ifa.ifa_ifp); ia->ia_garp_count = 0; if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz, garp_rexmit, ia) == 0) { ifa_ref(ifa); } IF_ADDR_WUNLOCK(ia->ia_ifa.ifa_ifp); } void arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa) { const struct sockaddr_in *dst_in; const struct sockaddr *dst; if (ifa->ifa_carp != NULL) return; dst = ifa->ifa_addr; dst_in = (const struct sockaddr_in *)dst; if (ntohl(dst_in->sin_addr.s_addr) == INADDR_ANY) return; arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp)); if (garp_rexmit_count > 0) { garp_timer_start(ifa); } arp_add_ifa_lle(ifp, dst); } void arp_announce_ifaddr(struct ifnet *ifp, struct in_addr addr, u_char *enaddr) { if (ntohl(addr.s_addr) != INADDR_ANY) arprequest(ifp, &addr, &addr, enaddr); } /* * Sends gratuitous ARPs for each ifaddr to notify other * nodes about the address change. */ static __noinline void arp_handle_ifllchange(struct ifnet *ifp) { struct ifaddr *ifa; TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) { if (ifa->ifa_addr->sa_family == AF_INET) arp_ifinit(ifp, ifa); } } /* * A handler for interface link layer address change event. */ static void arp_iflladdr(void *arg __unused, struct ifnet *ifp) { lltable_update_ifaddr(LLTABLE(ifp)); if ((ifp->if_flags & IFF_UP) != 0) arp_handle_ifllchange(ifp); } static void vnet_arp_init(void) { if (IS_DEFAULT_VNET(curvnet)) { netisr_register(&arp_nh); iflladdr_tag = EVENTHANDLER_REGISTER(iflladdr_event, arp_iflladdr, NULL, EVENTHANDLER_PRI_ANY); } #ifdef VIMAGE else netisr_register_vnet(&arp_nh); #endif } VNET_SYSINIT(vnet_arp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_SECOND, vnet_arp_init, 0); #ifdef VIMAGE /* * We have to unregister ARP along with IP otherwise we risk doing INADDR_HASH * lookups after destroying the hash. Ideally this would go on SI_ORDER_3.5. */ static void vnet_arp_destroy(__unused void *arg) { netisr_unregister_vnet(&arp_nh); } VNET_SYSUNINIT(vnet_arp_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, vnet_arp_destroy, NULL); #endif