/
if_ether.c
1524 lines (1349 loc) · 41.2 KB
/
if_ether.c
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/*-
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include <sys/param.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/lock.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_var.h>
#include <net/if_dl.h>
#include <net/if_private.h>
#include <net/if_types.h>
#include <net/netisr.h>
#include <net/ethernet.h>
#include <net/route.h>
#include <net/route/nhop.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/in_fib.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 <security/mac/mac_framework.h>
#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 | CTLFLAG_MPSAFE, 0,
"");
static SYSCTL_NODE(_net_link_ether, PF_ARP, arp,
CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
"");
/* timer values */
VNET_DEFINE_STATIC(int, arpt_keep) = (20*60); /* once resolved, good for 20
* minutes */
VNET_DEFINE_STATIC(int, arp_maxtries) = 5;
VNET_DEFINE_STATIC(int, arp_proxyall) = 0;
VNET_DEFINE_STATIC(int, arpt_down) = 20; /* keep incomplete entries for
* 20 seconds */
VNET_DEFINE_STATIC(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 */
VNET_DEFINE_STATIC(int, arp_maxhold) = 16;
#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");
VNET_DEFINE_STATIC(int, arp_log_level) = LOG_INFO; /* Min. log(9) level. */
#define V_arp_log_level VNET(arp_log_level)
SYSCTL_INT(_net_link_ether_arp, OID_AUTO, log_level, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(arp_log_level), 0,
"Minimum log(9) level for recording rate limited arp log messages. "
"The higher will be log more (emerg=0, info=6 (default), debug=7).");
#define ARP_LOG(pri, ...) do { \
if ((pri) <= V_arp_log_level && \
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, struct ifnet *ifp);
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;
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.
* Request usage feedback from the datapath.
* Change state and re-schedule ourselves.
*/
llentry_request_feedback(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:
if (llentry_get_hittime(lle) > 0 && lle->la_preempt > 0) {
/* Entry was used, issue refresh request */
struct epoch_tracker et;
struct in_addr dst;
dst = lle->r_l3addr.addr4;
lle->la_preempt--;
callout_schedule(&lle->lle_timer, hz * V_arpt_rexmit);
LLE_WUNLOCK(lle);
NET_EPOCH_ENTER(et);
arprequest(ifp, NULL, &dst, NULL);
NET_EPOCH_EXIT(et);
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
*/
static int
arprequest_internal(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;
NET_EPOCH_ASSERT();
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;
CK_STAILQ_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 (sip == NULL) {
printf("%s: cannot find matching address\n", __func__);
return (EADDRNOTAVAIL);
}
}
if (enaddr == NULL)
enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
return (ENOMEM);
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) {
m_freem(m);
ARP_LOG(LOG_ERR, "Failed to calculate ARP header on %s: %d\n",
if_name(ifp), error);
return (error);
}
ro.ro_prepend = linkhdr;
ro.ro_plen = linkhdrsize;
ro.ro_flags = 0;
m->m_flags |= M_BCAST;
m_clrprotoflags(m); /* Avoid confusing lower layers. */
error = (*ifp->if_output)(ifp, m, &sa, &ro);
ARPSTAT_INC(txrequests);
if (error) {
ARPSTAT_INC(txerrors);
ARP_LOG(LOG_DEBUG, "Failed to send ARP packet on %s: %d\n",
if_name(ifp), error);
}
return (error);
}
void
arprequest(struct ifnet *ifp, const struct in_addr *sip,
const struct in_addr *tip, u_char *enaddr)
{
(void) arprequest_internal(ifp, sip, tip, enaddr);
}
/*
* Resolve an IP address into an ethernet address - heavy version.
* Used internally by arpresolve().
* We have already checked that we can't use an existing lle without
* modification so we have to acquire an LLE_EXCLUSIVE lle lock.
*
* On success, desten and pflags 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;
int error, renew;
char *lladdr;
int ll_len;
NET_EPOCH_ASSERT();
if (pflags != NULL)
*pflags = 0;
if (plle != NULL)
*plle = NULL;
if ((flags & LLE_CREATE) == 0)
la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
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_provide_feedback(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) {
size_t dropped = lltable_append_entry_queue(la, m, V_arp_maxhold);
ARPSTAT_ADD(dropped, dropped);
}
/*
* 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, e;
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);
e = arprequest_internal(ifp, NULL, &SIN(dst)->sin_addr, NULL);
/*
* Only overwrite 'error' in case of error; in case of success
* the proper return value was already set above.
*/
if (e != 0)
return (e);
return (error);
}
LLE_WUNLOCK(la);
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;
NET_EPOCH_ASSERT();
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);
}
}
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_provide_feedback(la);
if (plle) {
LLE_ADDREF(la);
*plle = la;
LLE_WUNLOCK(la);
}
return (0);
}
if (plle && la)
LLE_WUNLOCK(la);
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_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 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 nhop_object *nh;
uint8_t linkhdr[LLE_MAX_LINKHDR];
struct route ro;
size_t linkhdrsize;
int lladdr_off;
int error;
char addrbuf[INET_ADDRSTRLEN];
NET_EPOCH_ASSERT();
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).
*/
CK_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);
goto match;
}
}
CK_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);
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) {
CK_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;
goto match;
}
}
}
#undef BDG_MEMBER_MATCHES_ARP
/*
* No match, use the first inet address on the receive interface
* as a dummy address for the rest of the function.
*/
CK_STAILQ_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);
goto match;
}
/*
* If bridging, fall back to using any inet address.
*/
if (!bridged || (ia = CK_STAILQ_FIRST(&V_in_ifaddrhead)) == NULL)
goto drop;
ifa_ref(&ia->ia_ifa);
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;
la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
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, ifp);
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: