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if_ether.c
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/*-
* 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.
* 4. 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/queue.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/netisr.h>
#include <net/if_llc.h>
#include <net/ethernet.h>
#include <net/route.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <net/if_llatbl.h>
#include <netinet/if_ether.h>
#ifdef INET
#include <netinet/ip_carp.h>
#endif
#include <net/if_arc.h>
#include <net/iso88025.h>
#include <security/mac/mac_framework.h>
#define SIN(s) ((const struct sockaddr_in *)(s))
#define SDL(s) ((struct sockaddr_dl *)s)
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, "");
static VNET_DEFINE(int, arp_carp_mac) = 0; /* default to disabled */
/* timer values */
static VNET_DEFINE(int, arpt_keep) = (20*60); /* once resolved, good for 20
* minutes */
static VNET_DEFINE(int, arp_maxtries) = 5;
VNET_DEFINE(int, useloopback) = 1; /* use loopback interface for
* local traffic */
static VNET_DEFINE(int, arp_proxyall) = 0;
static VNET_DEFINE(int, arpt_down) = 20; /* keep incomplete entries for
* 20 seconds */
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_arp_carp_mac VNET(arp_carp_mac)
#define V_arpt_keep VNET(arpt_keep)
#define V_arpt_down VNET(arpt_down)
#define V_arp_maxtries VNET(arp_maxtries)
#define V_arp_proxyall VNET(arp_proxyall)
#define V_arp_maxhold VNET(arp_maxhold)
SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, carp_mac, CTLFLAG_RW,
&VNET_NAME(arp_carp_mac), 0,
"Send CARP mac with replies to CARP ips");
SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
&VNET_NAME(arpt_keep), 0,
"ARP entry lifetime in seconds");
SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
&VNET_NAME(arp_maxtries), 0,
"ARP resolution attempts before returning error");
SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
&VNET_NAME(useloopback), 0,
"Use the loopback interface for local traffic");
SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
&VNET_NAME(arp_proxyall), 0,
"Enable proxy ARP for all suitable requests");
SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, wait, 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_VNET_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_RW,
&VNET_NAME(arp_maxhold), 0,
"Number of packets to hold per ARP entry");
/*
* 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");
static void arp_init(void);
static void arpintr(struct mbuf *);
static void arptimer(void *);
#ifdef INET
static void in_arpinput(struct mbuf *);
#endif
static const struct netisr_handler arp_nh = {
.nh_name = "arp",
.nh_handler = arpintr,
.nh_proto = NETISR_ARP,
.nh_policy = NETISR_POLICY_SOURCE,
};
#ifdef AF_INET
/*
* called by in_ifscrub to remove entry from the table when
* the interface goes away
*/
void
arp_ifscrub(struct ifnet *ifp, uint32_t addr)
{
struct sockaddr_in addr4;
bzero((void *)&addr4, sizeof(addr4));
addr4.sin_len = sizeof(addr4);
addr4.sin_family = AF_INET;
addr4.sin_addr.s_addr = addr;
IF_AFDATA_WLOCK(ifp);
lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
(struct sockaddr *)&addr4);
IF_AFDATA_WUNLOCK(ifp);
}
#endif
/*
* Timeout routine. Age arp_tab entries periodically.
*/
static void
arptimer(void *arg)
{
struct llentry *lle = (struct llentry *)arg;
struct ifnet *ifp;
if (lle->la_flags & LLE_STATIC) {
return;
}
LLE_WLOCK(lle);
if (callout_pending(&lle->la_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);
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->la_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) {
size_t pkts_dropped;
LLE_REMREF(lle);
pkts_dropped = llentry_free(lle);
ARPSTAT_ADD(dropped, pkts_dropped);
} else
LLE_FREE_LOCKED(lle);
IF_AFDATA_UNLOCK(ifp);
ARPSTAT_INC(timeouts);
CURVNET_RESTORE();
}
/*
* 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;
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_data.ifi_addrlen;
m->m_pkthdr.len = m->m_len;
MH_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;
m->m_flags |= M_BCAST;
m_clrprotoflags(m); /* Avoid confusing lower layers. */
(*ifp->if_output)(ifp, m, &sa, NULL);
ARPSTAT_INC(txrequests);
}
/*
* Resolve an IP address into an ethernet address.
* On input:
* ifp is the interface we use
* rt0 is the route to the final destination (possibly useless)
* m is the mbuf. May be NULL if we don't have a packet.
* dst is the next hop,
* desten is where we want the address.
*
* On success, desten is 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, struct rtentry *rt0, struct mbuf *m,
const struct sockaddr *dst, u_char *desten, struct llentry **lle)
{
struct llentry *la = 0;
u_int flags = 0;
struct mbuf *curr = NULL;
struct mbuf *next = NULL;
int error, renew;
*lle = 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 && ifp->if_type != IFT_ARCNET) {
/* multicast */
ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
return (0);
}
}
retry:
IF_AFDATA_RLOCK(ifp);
la = lla_lookup(LLTABLE(ifp), flags, dst);
IF_AFDATA_RUNLOCK(ifp);
if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
&& ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
flags |= (LLE_CREATE | LLE_EXCLUSIVE);
IF_AFDATA_WLOCK(ifp);
la = lla_lookup(LLTABLE(ifp), flags, dst);
IF_AFDATA_WUNLOCK(ifp);
}
if (la == NULL) {
if (flags & LLE_CREATE)
log(LOG_DEBUG,
"arpresolve: can't allocate llinfo for %s on %s\n",
inet_ntoa(SIN(dst)->sin_addr), ifp->if_xname);
m_freem(m);
return (EINVAL);
}
if ((la->la_flags & LLE_VALID) &&
((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
bcopy(&la->ll_addr, desten, ifp->if_addrlen);
renew = 0;
/*
* If entry has an expiry time and it is approaching,
* see if we need to send an ARP request within this
* arpt_down interval.
*/
if (!(la->la_flags & LLE_STATIC) &&
time_uptime + la->la_preempt > la->la_expire) {
renew = 1;
la->la_preempt--;
}
*lle = la;
if (flags & LLE_EXCLUSIVE)
LLE_WUNLOCK(la);
else
LLE_RUNLOCK(la);
if (renew == 1)
arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
return (0);
}
if (la->la_flags & LLE_STATIC) { /* should not happen! */
log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
inet_ntoa(SIN(dst)->sin_addr));
m_freem(m);
error = EINVAL;
goto done;
}
renew = (la->la_asked == 0 || la->la_expire != time_uptime);
if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
flags |= LLE_EXCLUSIVE;
LLE_RUNLOCK(la);
goto retry;
}
/*
* 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++;
if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
flags &= ~LLE_EXCLUSIVE;
LLE_DOWNGRADE(la);
}
}
/*
* 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 = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ?
EHOSTUNREACH : EHOSTDOWN;
if (renew) {
int canceled;
LLE_ADDREF(la);
la->la_expire = time_uptime;
canceled = callout_reset(&la->la_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);
}
done:
if (flags & LLE_EXCLUSIVE)
LLE_WUNLOCK(la);
else
LLE_RUNLOCK(la);
return (error);
}
/*
* Common length and type checks are done here,
* then the protocol-specific routine is called.
*/
static void
arpintr(struct mbuf *m)
{
struct arphdr *ar;
if (m->m_len < sizeof(struct arphdr) &&
((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n");
return;
}
ar = mtod(m, struct arphdr *);
if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 &&
ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) {
log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)"
" (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "",
ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":",
ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":");
m_freem(m);
return;
}
if (m->m_len < arphdr_len(ar)) {
if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
log(LOG_NOTICE, "arp: runt packet\n");
m_freem(m);
return;
}
ar = mtod(m, struct arphdr *);
}
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;
static struct timeval arp_lastlog;
static int arp_curpps;
static int arp_maxpps = 1;
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");
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");
#define ARP_LOG(pri, ...) do { \
if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps)) \
log((pri), "arp: " __VA_ARGS__); \
} while (0)
static void
in_arpinput(struct mbuf *m)
{
struct arphdr *ah;
struct ifnet *ifp = m->m_pkthdr.rcvif;
struct llentry *la = NULL;
struct rtentry *rt;
struct ifaddr *ifa;
struct in_ifaddr *ia;
struct sockaddr sa;
struct in_addr isaddr, itaddr, myaddr;
u_int8_t *enaddr = NULL;
int op, flags;
int req_len;
int bridged = 0, is_bridge = 0;
int carped;
struct sockaddr_in sin;
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;
req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
ARP_LOG(LOG_NOTICE, "runt packet -- m_pullup failed\n");
return;
}
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();
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();
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();
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();
goto match;
}
}
}
#undef BDG_MEMBER_MATCHES_ARP
IN_IFADDR_RUNLOCK();
/*
* 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();
if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
IN_IFADDR_RUNLOCK();
goto drop;
}
ifa_ref(&ia->ia_ifa);
IN_IFADDR_RUNLOCK();
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(isaddr));
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(isaddr), 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;
flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
flags |= LLE_EXCLUSIVE;
IF_AFDATA_LOCK(ifp);
la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
IF_AFDATA_UNLOCK(ifp);
if (la != NULL) {
/* 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(isaddr),
la->lle_tbl->llt_ifp->if_xname,
ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
ifp->if_xname);
LLE_WUNLOCK(la);
goto reply;
}
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(isaddr), ifp->if_xname);
goto reply;
}
if (log_arp_movements) {
ARP_LOG(LOG_INFO, "%s moved from %*D "
"to %*D on %s\n",
inet_ntoa(isaddr),
ifp->if_addrlen,
(u_char *)&la->ll_addr, ":",
ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
ifp->if_xname);
}
}
if (ifp->if_addrlen != ah->ar_hln) {
LLE_WUNLOCK(la);
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;
}
(void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
la->la_flags |= LLE_VALID;
EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
if (!(la->la_flags & LLE_STATIC)) {
int canceled;
LLE_ADDREF(la);
la->la_expire = time_uptime + V_arpt_keep;
canceled = callout_reset(&la->la_timer,
hz * V_arpt_keep, arptimer, la);
if (canceled)
LLE_REMREF(la);
}
la->la_asked = 0;
la->la_preempt = V_arp_maxtries;
/*
* 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) {
struct mbuf *m_hold, *m_hold_next;
m_hold = la->la_hold;
la->la_hold = NULL;
la->la_numheld = 0;
memcpy(&sa, L3_ADDR(la), sizeof(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);
}
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;
sin.sin_addr = itaddr;
/* XXX MRT use table 0 for arp reply */
rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
if (!rt)
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 (!rt->rt_ifp || rt->rt_ifp == ifp) {
RTFREE_LOCKED(rt);
goto drop;
}
RTFREE_LOCKED(rt);
(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.
*/
sin.sin_addr = isaddr;
/* XXX MRT use table 0 for arp checks */
rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
if (!rt)
goto drop;
if (rt->rt_ifp != ifp) {
ARP_LOG(LOG_INFO, "proxy: ignoring request"
" from %s via %s, expecting %s\n",
inet_ntoa(isaddr), ifp->if_xname,
rt->rt_ifp->if_xname);
RTFREE_LOCKED(rt);
goto drop;
}
RTFREE_LOCKED(rt);
#ifdef DEBUG_PROXY
printf("arp: proxying for %s\n", inet_ntoa(itaddr));
#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(itaddr));
#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);
}
#ifdef DEV_CARP
if (V_arp_carp_mac && carp_match) {
struct ether_header *eh = (struct ether_header *) sa.sa_data;
short type = htons(ETHERTYPE_ARP);
ah->ar_hrd = htons(ARPHRD_ETHER);
(void)memcpy(&eh->ether_type, &type,
sizeof(eh->ether_type));
(void)memcpy(eh->ether_dhost, ar_tha(ah),
sizeof (eh->ether_dhost));
(void)memcpy(eh->ether_shost, enaddr,
sizeof(eh->ether_shost));
sa.sa_family = pseudo_AF_HDRCMPLT;
sa.sa_len = sizeof(sa);
} else {
#endif
sa.sa_family = AF_ARP;
sa.sa_len = 2;
#ifdef DEV_CARP
}
#endif
(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;
m_clrprotoflags(m); /* Avoid confusing lower layers. */
(*ifp->if_output)(ifp, m, &sa, NULL);
ARPSTAT_INC(txreplies);
return;
drop:
m_freem(m);
}
#endif
/*
* 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;