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freebsd-dev/sys/netinet/if_ether.c
Gleb Smirnoff b8a6e03fac Widen NET_EPOCH coverage. 
When epoch(9) was introduced to network stack, it was basically
dropped in place of existing locking, which was mutexes and
rwlocks. For the sake of performance mutex covered areas were
as small as possible, so became epoch covered areas.

However, epoch doesn't introduce any contention, it just delays
memory reclaim. So, there is no point to minimise epoch covered
areas in sense of performance. Meanwhile entering/exiting epoch
also has non-zero CPU usage, so doing this less often is a win.

Not the least is also code maintainability. In the new paradigm
we can assume that at any stage of processing a packet, we are
inside network epoch. This makes coding both input and output
path way easier.

On output path we already enter epoch quite early - in the
ip_output(), in the ip6_output().

This patch does the same for the input path. All ISR processing,
network related callouts, other ways of packet injection to the
network stack shall be performed in net_epoch. Any leaf function
that walks network configuration now asserts epoch.

Tricky part is configuration code paths - ioctls, sysctls. They
also call into leaf functions, so some need to be changed.

This patch would introduce more epoch recursions (see EPOCH_TRACE)
than we had before. They will be cleaned up separately, as several
of them aren't trivial. Note, that unlike a lock recursion the
epoch recursion is safe and just wastes a bit of resources.

Reviewed by:	gallatin, hselasky, cy, adrian, kristof
Differential Revision:	https://reviews.freebsd.org/D19111
2019-10-07 22:40:05 +00:00

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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/rmlock.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_types.h>
#include <net/netisr.h>
#include <net/ethernet.h>
#include <net/route.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, 0, "");
static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 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) = 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");
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);
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 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) {
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;
struct mbuf *curr = NULL;
struct mbuf *next = NULL;
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_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, 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_mark_used(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 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];
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).
*/
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.
*/
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.
*/
IN_IFADDR_RLOCK(&in_ifa_tracker);
if (!bridged || (ia = CK_STAILQ_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;
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);
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;
lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
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;
}
CURVNET_SET(ia->ia_ifa.ifa_ifp->if_vnet);
/*
* 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);
}
}
CURVNET_RESTORE();
}
/*
* 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)
{
struct epoch_tracker et;
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;
NET_EPOCH_ENTER(et);
arp_announce_ifaddr(ifp, dst_in->sin_addr, IF_LLADDR(ifp));
NET_EPOCH_EXIT(et);
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;
CK_STAILQ_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
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