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freebsd/sys/netinet/if_ether.c
Philip Paeps 80b11ee46a Fix ARP in bridging scenarios where the bridge shares its 
MAC address with one of its members (see my r180140).

Pointy hat to:	philip
Submitted by:	Eygene Ryabinkin <rea-fbsd@codelabs.ru>
MFC after:	3 days
2008-08-18 09:06:11 +00:00

1070 lines
30 KiB
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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 "opt_mac.h"
#include "opt_carp.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/socket.h>
#include <sys/syslog.h>
#include <sys/vimage.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/if_llc.h>
#include <net/ethernet.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/if_ether.h>
#include <net/if_arc.h>
#include <net/iso88025.h>
#ifdef DEV_CARP
#include <netinet/ip_carp.h>
#endif
#include <security/mac/mac_framework.h>
#define SIN(s) ((struct sockaddr_in *)s)
#define SDL(s) ((struct sockaddr_dl *)s)
SYSCTL_DECL(_net_link_ether);
SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
/* timer values */
static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
&arpt_keep, 0, "ARP entry lifetime in seconds");
#define rt_expire rt_rmx.rmx_expire
struct llinfo_arp {
struct callout la_timer;
struct rtentry *la_rt;
struct mbuf *la_hold; /* last packet until resolved/timeout */
u_short la_preempt; /* countdown for pre-expiry arps */
u_short la_asked; /* # requests sent */
};
static struct ifqueue arpintrq;
static int arp_allocated;
static int arp_maxtries = 5;
static int useloopback = 1; /* use loopback interface for local traffic */
static int arp_proxyall = 0;
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
&arp_maxtries, 0, "ARP resolution attempts before returning error");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
&useloopback, 0, "Use the loopback interface for local traffic");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
&arp_proxyall, 0, "Enable proxy ARP for all suitable requests");
static void arp_init(void);
static void arp_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
static void arprequest(struct ifnet *,
struct in_addr *, struct in_addr *, u_char *);
static void arpintr(struct mbuf *);
static void arptimer(void *);
static struct rtentry
*arplookup(u_long, int, int, int);
#ifdef INET
static void in_arpinput(struct mbuf *);
#endif
/*
* Timeout routine.
*/
static void
arptimer(void *arg)
{
struct rtentry *rt = (struct rtentry *)arg;
RT_LOCK_ASSERT(rt);
/*
* The lock is needed to close a theoretical race
* between spontaneous expiry and intentional removal.
* We still got an extra reference on rtentry, so can
* safely pass pointers to its contents.
*/
RT_UNLOCK(rt);
in_rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL,
rt->rt_fibnum);
}
/*
* Parallel to llc_rtrequest.
*/
static void
arp_rtrequest(int req, struct rtentry *rt, struct rt_addrinfo *info)
{
struct sockaddr *gate;
struct llinfo_arp *la;
static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
struct in_ifaddr *ia;
struct ifaddr *ifa;
RT_LOCK_ASSERT(rt);
if (rt->rt_flags & RTF_GATEWAY)
return;
gate = rt->rt_gateway;
la = (struct llinfo_arp *)rt->rt_llinfo;
switch (req) {
case RTM_ADD:
/*
* XXX: If this is a manually added route to interface
* such as older version of routed or gated might provide,
* restore cloning bit.
*/
if ((rt->rt_flags & RTF_HOST) == 0 &&
rt_mask(rt) != NULL &&
SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
rt->rt_flags |= RTF_CLONING;
if (rt->rt_flags & RTF_CLONING) {
/*
* Case 1: This route should come from a route to iface.
*/
rt_setgate(rt, rt_key(rt),
(struct sockaddr *)&null_sdl);
gate = rt->rt_gateway;
SDL(gate)->sdl_type = rt->rt_ifp->if_type;
SDL(gate)->sdl_index = rt->rt_ifp->if_index;
rt->rt_expire = time_uptime;
break;
}
/* Announce a new entry if requested. */
if (rt->rt_flags & RTF_ANNOUNCE)
arprequest(rt->rt_ifp,
&SIN(rt_key(rt))->sin_addr,
&SIN(rt_key(rt))->sin_addr,
(u_char *)LLADDR(SDL(gate)));
/*FALLTHROUGH*/
case RTM_RESOLVE:
if (gate->sa_family != AF_LINK ||
gate->sa_len < sizeof(null_sdl)) {
log(LOG_DEBUG, "%s: bad gateway %s%s\n", __func__,
inet_ntoa(SIN(rt_key(rt))->sin_addr),
(gate->sa_family != AF_LINK) ?
" (!AF_LINK)": "");
break;
}
SDL(gate)->sdl_type = rt->rt_ifp->if_type;
SDL(gate)->sdl_index = rt->rt_ifp->if_index;
if (la != 0)
break; /* This happens on a route change */
/*
* Case 2: This route may come from cloning, or a manual route
* add with a LL address.
*/
R_Zalloc(la, struct llinfo_arp *, sizeof(*la));
rt->rt_llinfo = (caddr_t)la;
if (la == 0) {
log(LOG_DEBUG, "%s: malloc failed\n", __func__);
break;
}
arp_allocated++;
/*
* We are storing a route entry outside of radix tree. So,
* it can be found and accessed by other means than radix
* lookup. The routing code assumes that any rtentry detached
* from radix can be destroyed safely. To prevent this, we
* add an additional reference.
*/
RT_ADDREF(rt);
la->la_rt = rt;
rt->rt_flags |= RTF_LLINFO;
callout_init_mtx(&la->la_timer, &rt->rt_mtx,
CALLOUT_RETURNUNLOCKED);
#ifdef INET
/*
* This keeps the multicast addresses from showing up
* in `arp -a' listings as unresolved. It's not actually
* functional. Then the same for broadcast.
*/
if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr)) &&
rt->rt_ifp->if_type != IFT_ARCNET) {
ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr,
LLADDR(SDL(gate)));
SDL(gate)->sdl_alen = 6;
rt->rt_expire = 0;
}
if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
memcpy(LLADDR(SDL(gate)), rt->rt_ifp->if_broadcastaddr,
rt->rt_ifp->if_addrlen);
SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen;
rt->rt_expire = 0;
}
#endif
TAILQ_FOREACH(ia, &V_in_ifaddrhead, ia_link) {
if (ia->ia_ifp == rt->rt_ifp &&
SIN(rt_key(rt))->sin_addr.s_addr ==
(IA_SIN(ia))->sin_addr.s_addr)
break;
}
if (ia) {
/*
* This test used to be
* if (loif.if_flags & IFF_UP)
* It allowed local traffic to be forced
* through the hardware by configuring the loopback down.
* However, it causes problems during network configuration
* for boards that can't receive packets they send.
* It is now necessary to clear "useloopback" and remove
* the route to force traffic out to the hardware.
*/
rt->rt_expire = 0;
bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)),
SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen);
if (V_useloopback) {
rt->rt_ifp = V_loif;
rt->rt_rmx.rmx_mtu = V_loif->if_mtu;
}
/*
* make sure to set rt->rt_ifa to the interface
* address we are using, otherwise we will have trouble
* with source address selection.
*/
ifa = &ia->ia_ifa;
if (ifa != rt->rt_ifa) {
IFAFREE(rt->rt_ifa);
IFAREF(ifa);
rt->rt_ifa = ifa;
}
}
break;
case RTM_DELETE:
if (la == NULL) /* XXX: at least CARP does this. */
break;
callout_stop(&la->la_timer);
rt->rt_llinfo = NULL;
rt->rt_flags &= ~RTF_LLINFO;
RT_REMREF(rt);
if (la->la_hold)
m_freem(la->la_hold);
Free((caddr_t)la);
}
}
/*
* Broadcast an ARP request. Caller specifies:
* - arp header source ip address
* - arp header target ip address
* - arp header source ethernet address
*/
static void
arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,
u_char *enaddr)
{
struct mbuf *m;
struct arphdr *ah;
struct sockaddr sa;
if ((m = m_gethdr(M_DONTWAIT, 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((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
sa.sa_family = AF_ARP;
sa.sa_len = 2;
m->m_flags |= M_BCAST;
(*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
return;
}
/*
* 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,
struct sockaddr *dst, u_char *desten)
{
struct llinfo_arp *la = NULL;
struct rtentry *rt = NULL;
struct sockaddr_dl *sdl;
int error;
int fibnum = 0;
if (m) {
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);
}
fibnum = M_GETFIB(m);
}
if (rt0 != NULL) {
/* Look for a cached arp (ll) entry. */
if (m == NULL)
fibnum = rt0->rt_fibnum;
error = in_rt_check(&rt, &rt0, dst, fibnum);
if (error) {
m_freem(m);
return error;
}
la = (struct llinfo_arp *)rt->rt_llinfo;
if (la == NULL)
RT_UNLOCK(rt);
}
if (la == NULL) {
/*
* We enter this block if rt0 was NULL,
* or if rt found by in_rt_check() didn't have llinfo.
* we should get a cloned route, which since it should
* come from the local interface should have a ll entry.
* if may be incoplete but that's ok.
* XXXMRT if we haven't found a fibnum is that OK?
*/
rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0, fibnum);
if (rt == NULL) {
log(LOG_DEBUG,
"arpresolve: can't allocate route for %s\n",
inet_ntoa(SIN(dst)->sin_addr));
m_freem(m);
return (EINVAL); /* XXX */
}
la = (struct llinfo_arp *)rt->rt_llinfo;
if (la == NULL) {
RT_UNLOCK(rt);
log(LOG_DEBUG,
"arpresolve: can't allocate llinfo for %s\n",
inet_ntoa(SIN(dst)->sin_addr));
m_freem(m);
return (EINVAL); /* XXX */
}
}
sdl = SDL(rt->rt_gateway);
/*
* Check the address family and length is valid, the address
* is resolved; otherwise, try to resolve.
*/
if ((rt->rt_expire == 0 || rt->rt_expire > time_uptime) &&
sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) {
bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
/*
* If entry has an expiry time and it is approaching,
* send an ARP request.
*/
if ((rt->rt_expire != 0) &&
(time_uptime + la->la_preempt > rt->rt_expire)) {
struct in_addr sin =
SIN(rt->rt_ifa->ifa_addr)->sin_addr;
la->la_preempt--;
RT_UNLOCK(rt);
arprequest(ifp, &sin, &SIN(dst)->sin_addr,
IF_LLADDR(ifp));
return (0);
}
RT_UNLOCK(rt);
return (0);
}
/*
* If ARP is disabled or static on this interface, stop.
* XXX
* Probably should not allocate empty llinfo struct if we are
* not going to be sending out an arp request.
*/
if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) {
RT_UNLOCK(rt);
m_freem(m);
return (EINVAL);
}
/*
* There is an arptab entry, but no ethernet address
* response yet. Replace the held mbuf with this
* latest one.
*/
if (m) {
if (la->la_hold)
m_freem(la->la_hold);
la->la_hold = m;
}
KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry"));
/*
* 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 = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH;
if (la->la_asked == 0 || rt->rt_expire != time_uptime) {
struct in_addr sin =
SIN(rt->rt_ifa->ifa_addr)->sin_addr;
rt->rt_expire = time_uptime;
callout_reset(&la->la_timer, hz, arptimer, rt);
la->la_asked++;
RT_UNLOCK(rt);
arprequest(ifp, &sin, &SIN(dst)->sin_addr,
IF_LLADDR(ifp));
} else
RT_UNLOCK(rt);
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_ERR, "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) {
log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
(unsigned char *)&ar->ar_hrd, "");
m_freem(m);
return;
}
if (m->m_len < arphdr_len(ar)) {
if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
log(LOG_ERR, "arp: runt packet\n");
m_freem(m);
return;
}
ar = mtod(m, struct arphdr *);
}
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;
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");
static void
in_arpinput(struct mbuf *m)
{
struct arphdr *ah;
struct ifnet *ifp = m->m_pkthdr.rcvif;
struct llinfo_arp *la;
struct rtentry *rt;
struct ifaddr *ifa;
struct in_ifaddr *ia;
struct sockaddr_dl *sdl;
struct sockaddr sa;
struct in_addr isaddr, itaddr, myaddr;
struct mbuf *hold;
u_int8_t *enaddr = NULL;
int op, rif_len;
int req_len;
int bridged = 0, is_bridge = 0;
u_int fibnum;
u_int goodfib = 0;
int firstpass = 1;
#ifdef DEV_CARP
int carp_match = 0;
#endif
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) {
log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
return;
}
ah = mtod(m, struct arphdr *);
op = ntohs(ah->ar_op);
(void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
(void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
/*
* For a bridge, we want to check the address irrespective
* of the receive interface. (This will change slightly
* when we have clusters of interfaces).
* If the interface does not match, but the recieving interface
* is part of carp, we call carp_iamatch to see if this is a
* request for the virtual host ip.
* XXX: This is really ugly!
*/
LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
(ia->ia_ifp == ifp)) &&
itaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
goto match;
#ifdef DEV_CARP
if (ifp->if_carp != NULL &&
carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) &&
itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
carp_match = 1;
goto match;
}
#endif
}
LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
(ia->ia_ifp == ifp)) &&
isaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
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)) {
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.
*/
TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
if (ifa->ifa_addr->sa_family == AF_INET) {
ia = ifatoia(ifa);
goto match;
}
/*
* If bridging, fall back to using any inet address.
*/
if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL)
goto drop;
match:
if (!enaddr)
enaddr = (u_int8_t *)IF_LLADDR(ifp);
myaddr = ia->ia_addr.sin_addr;
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)) {
log(LOG_ERR,
"arp: 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 && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
log(LOG_ERR,
"arp: %*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;
goto reply;
}
if (ifp->if_flags & IFF_STATICARP)
goto reply;
/*
* We look for any FIBs that has this address to find
* the interface etc.
* For sanity checks that are FIB independent we abort the loop.
*/
for (fibnum = 0; fibnum < rt_numfibs; fibnum++) {
rt = arplookup(isaddr.s_addr,
itaddr.s_addr == myaddr.s_addr, 0, fibnum);
if (rt == NULL)
continue;
sdl = SDL(rt->rt_gateway);
/* Only call this once */
if (firstpass) {
sin.sin_addr.s_addr = isaddr.s_addr;
EVENTHANDLER_INVOKE(route_arp_update_event, rt,
ar_sha(ah), (struct sockaddr *)&sin);
}
la = (struct llinfo_arp *)rt->rt_llinfo;
if (la == NULL) {
RT_UNLOCK(rt);
continue;
}
if (firstpass) {
/* The following is not an error when doing bridging. */
if (!bridged && rt->rt_ifp != ifp
#ifdef DEV_CARP
&& (ifp->if_type != IFT_CARP || !carp_match)
#endif
) {
if (log_arp_wrong_iface)
log(LOG_ERR, "arp: %s is on %s "
"but got reply from %*D "
"on %s\n",
inet_ntoa(isaddr),
rt->rt_ifp->if_xname,
ifp->if_addrlen,
(u_char *)ar_sha(ah), ":",
ifp->if_xname);
RT_UNLOCK(rt);
break;
}
if (sdl->sdl_alen &&
bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) {
if (rt->rt_expire) {
if (log_arp_movements)
log(LOG_INFO,
"arp: %s moved from %*D to %*D "
"on %s\n",
inet_ntoa(isaddr),
ifp->if_addrlen,
(u_char *)LLADDR(sdl), ":",
ifp->if_addrlen,
(u_char *)ar_sha(ah), ":",
ifp->if_xname);
} else {
RT_UNLOCK(rt);
if (log_arp_permanent_modify)
log(LOG_ERR,
"arp: %*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);
break;
}
}
/*
* sanity check for the address length.
* XXX this does not work for protocols
* with variable address length. -is
*/
if (sdl->sdl_alen &&
sdl->sdl_alen != ah->ar_hln) {
log(LOG_WARNING,
"arp from %*D: new addr len %d, was %d",
ifp->if_addrlen, (u_char *) ar_sha(ah),
":", ah->ar_hln, sdl->sdl_alen);
}
if (ifp->if_addrlen != ah->ar_hln) {
log(LOG_WARNING,
"arp from %*D: addr len: "
"new %d, i/f %d (ignored)",
ifp->if_addrlen, (u_char *) ar_sha(ah),
":", ah->ar_hln, ifp->if_addrlen);
RT_UNLOCK(rt);
break;
}
firstpass = 0;
goodfib = fibnum;
}
/* Copy in the information received. */
(void)memcpy(LLADDR(sdl), ar_sha(ah),
sdl->sdl_alen = ah->ar_hln);
/*
* If we receive an arp from a token-ring station over
* a token-ring nic then try to save the source routing info.
* XXXMRT Only minimal Token Ring support for MRT.
* Only do this on the first pass as if modifies the mbuf.
*/
if (ifp->if_type == IFT_ISO88025) {
struct iso88025_header *th = NULL;
struct iso88025_sockaddr_dl_data *trld;
/* force the fib loop to end after this pass */
fibnum = rt_numfibs - 1;
th = (struct iso88025_header *)m->m_pkthdr.header;
trld = SDL_ISO88025(sdl);
rif_len = TR_RCF_RIFLEN(th->rcf);
if ((th->iso88025_shost[0] & TR_RII) &&
(rif_len > 2)) {
trld->trld_rcf = th->rcf;
trld->trld_rcf ^= htons(TR_RCF_DIR);
memcpy(trld->trld_route, th->rd, rif_len - 2);
trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK);
/*
* Set up source routing information for
* reply packet (XXX)
*/
m->m_data -= rif_len;
m->m_len += rif_len;
m->m_pkthdr.len += rif_len;
} else {
th->iso88025_shost[0] &= ~TR_RII;
trld->trld_rcf = 0;
}
m->m_data -= 8;
m->m_len += 8;
m->m_pkthdr.len += 8;
th->rcf = trld->trld_rcf;
}
if (rt->rt_expire) {
rt->rt_expire = time_uptime + V_arpt_keep;
callout_reset(&la->la_timer, hz * V_arpt_keep,
arptimer, rt);
}
la->la_asked = 0;
la->la_preempt = V_arp_maxtries;
hold = la->la_hold;
la->la_hold = NULL;
RT_UNLOCK(rt);
if (hold != NULL)
(*ifp->if_output)(ifp, hold, rt_key(rt), rt);
} /* end of FIB loop */
reply:
/*
* Decide if we have to respond to something.
*/
if (op != ARPOP_REQUEST)
goto drop;
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 {
/* It's not asking for our address. But it still may
* be something we should answer.
*
* XXX MRT
* We assume that link level info is independent of
* the table used and so we use whichever we can and don't
* have a better option.
*/
/* Have we been asked to proxy for the target. */
rt = arplookup(itaddr.s_addr, 0, SIN_PROXY, goodfib);
if (rt == NULL) {
/* Nope, only intersted now if proxying everything. */
struct sockaddr_in sin;
if (!V_arp_proxyall)
goto drop;
bzero(&sin, sizeof sin);
sin.sin_family = AF_INET;
sin.sin_len = sizeof sin;
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 == ifp) {
rtfree(rt);
goto drop;
}
(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
(void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
rtfree(rt);
/*
* Also check that the node which sent the ARP packet
* is on the 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) {
log(LOG_INFO, "arp_proxy: ignoring request"
" from %s via %s, expecting %s\n",
inet_ntoa(isaddr), ifp->if_xname,
rt->rt_ifp->if_xname);
rtfree(rt);
goto drop;
}
rtfree(rt);
#ifdef DEBUG_PROXY
printf("arp: proxying for %s\n",
inet_ntoa(itaddr));
#endif
} else {
/*
* Return proxied ARP replies only on the interface
* or bridge cluster where this network resides.
* Otherwise we may conflict with the host we are
* proxying for.
*/
if (rt->rt_ifp != ifp &&
(rt->rt_ifp->if_bridge != ifp->if_bridge ||
ifp->if_bridge == NULL)) {
RT_UNLOCK(rt);
goto drop;
}
sdl = SDL(rt->rt_gateway);
(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
(void)memcpy(ar_sha(ah), LLADDR(sdl), ah->ar_hln);
RT_UNLOCK(rt);
}
}
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);
}
(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;
sa.sa_family = AF_ARP;
sa.sa_len = 2;
(*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
return;
drop:
m_freem(m);
}
#endif
/*
* Lookup or enter a new address in arptab.
*/
static struct rtentry *
arplookup(u_long addr, int create, int proxy, int fibnum)
{
struct rtentry *rt;
struct sockaddr_inarp sin;
const char *why = 0;
bzero(&sin, sizeof(sin));
sin.sin_len = sizeof(sin);
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = addr;
if (proxy)
sin.sin_other = SIN_PROXY;
rt = in_rtalloc1((struct sockaddr *)&sin, create, 0UL, fibnum);
if (rt == 0)
return (0);
if (rt->rt_flags & RTF_GATEWAY)
why = "host is not on local network";
else if ((rt->rt_flags & RTF_LLINFO) == 0)
why = "could not allocate llinfo";
else if (rt->rt_gateway->sa_family != AF_LINK)
why = "gateway route is not ours";
if (why) {
#define ISDYNCLONE(_rt) \
(((_rt)->rt_flags & (RTF_STATIC | RTF_WASCLONED)) == RTF_WASCLONED)
if (create)
log(LOG_DEBUG, "arplookup %s failed: %s\n",
inet_ntoa(sin.sin_addr), why);
/*
* If there are no references to this Layer 2 route,
* and it is a cloned route, and not static, and
* arplookup() is creating the route, then purge
* it from the routing table as it is probably bogus.
*/
if (rt->rt_refcnt == 1 && ISDYNCLONE(rt))
rtexpunge(rt);
RTFREE_LOCKED(rt);
return (0);
#undef ISDYNCLONE
} else {
RT_REMREF(rt);
return (rt);
}
}
void
arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
{
if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
arprequest(ifp, &IA_SIN(ifa)->sin_addr,
&IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
ifa->ifa_rtrequest = arp_rtrequest;
ifa->ifa_flags |= RTF_CLONING;
}
void
arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
{
if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
arprequest(ifp, &IA_SIN(ifa)->sin_addr,
&IA_SIN(ifa)->sin_addr, enaddr);
ifa->ifa_rtrequest = arp_rtrequest;
ifa->ifa_flags |= RTF_CLONING;
}
static void
arp_init(void)
{
arpintrq.ifq_maxlen = 50;
mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF);
netisr_register(NETISR_ARP, arpintr, &arpintrq, 0);
}
SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);
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