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freebsd/sys/net/bridge.c

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/*
* Copyright (c) 1998 Luigi Rizzo
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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.
*
*/
/*
* This code implements bridging in FreeBSD. It only acts on ethernet
* type of interfaces (others are still usable for routing).
* A bridging table holds the source MAC address/dest. interface for each
* known node. The table is indexed using an hash of the source address.
*
* Input packets are tapped near the end of the input routine in each
* driver (near the call to bpf_mtap, or before the call to ether_input)
* and analysed calling bridge_in(). Depending on the result, the packet
* can be forwarded to one or more output interfaces using bdg_forward(),
* and/or sent to the upper layer (e.g. in case of multicast).
*
* Output packets are intercepted near the end of ether_output(),
* the correct destination is selected calling bdg_dst_lookup(),
* and then forwarding is done using bdg_forward().
* Bridging is controlled by the sysctl variable net.link.ether.bridge
*
* The arp code is also modified to let a machine answer to requests
* irrespective of the port the request came from.
*
* In case of loops in the bridging topology, the bridge detects this
* event and temporarily mutes output bridging on one of the ports.
* Periodically, interfaces are unmuted by bdg_timeout(). (For the
* mute flag i am temporarily using IFF_LINK2 but this has to
* change.) Muting is only implemented as a safety measure, and also as
* a mechanism to support a user-space implementation of the spanning
* tree algorithm. In the final release, unmuting will only occur
* because of explicit action of the user-level daemon.
*
* To build a bridging kernel, use the following option
* option BRIDGE
* and then at runtime set the sysctl variable to enable bridging.
*
* Only one interface is supposed to have addresses set (but
* there are no problems in practice if you set addresses for more
* than one interface).
* Bridging will act before routing, but nothing prevents a machine
* from doing both (modulo bugs in the implementation...).
*
* THINGS TO REMEMBER
* - bridging requires some (small) modifications to the interface
* driver. Currently (980911) the "ed", "de", "tx", "lnc" drivers
* have been modified and tested. "fxp", "ep", "fe" have been
* modified but not tested. See the "ed" and "de" drivers as
* examples on how to operate.
* - bridging is incompatible with multicast routing on the same
* machine. There is not an easy fix to this.
* - loop detection is still not very robust.
* - the interface of bdg_forward() could be improved.
*/
#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/systm.h>
#include <sys/socket.h> /* for net/if.h */
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_types.h>
#include <netinet/in.h> /* for struct arpcom */
#include <netinet/if_ether.h> /* for struct arpcom */
#include "opt_ipfw.h"
#include "opt_ipdn.h"
#if defined(IPFIREWALL) && defined(DUMMYNET)
#include <net/route.h>
#include <netinet/ip_fw.h>
#include <netinet/ip_dummynet.h>
#endif
#include <net/bridge.h>
/*
* For debugging, you can use the following macros.
* remember, rdtsc() only works on Pentium-class machines
quad_t ticks;
DDB(ticks = rdtsc();)
... interesting code ...
DDB(bdg_fw_ticks += (u_long)(rdtsc() - ticks) ; bdg_fw_count++ ;)
*
*/
#define DDB(x) x
#define DEB(x)
/*
* System initialization
*/
static void bdginit(void *);
static void flush_table(void);
SYSINIT(interfaces, SI_SUB_PROTO_IF, SI_ORDER_FIRST, bdginit, NULL)
static int bdg_ipfw = 0 ;
int do_bridge = 0;
bdg_hash_table *bdg_table = NULL ;
/*
* we need additional info for the bridge. The bdg_ifp2sc[] array
* provides a pointer to this struct using the if_index.
* bdg_softc has a backpointer to the struct ifnet, the bridge
* flags, and a group (bridging occurs only between port of the
* same group).
*/
struct bdg_softc {
struct ifnet *ifp ;
/* ((struct arpcom *)ifp)->ac_enaddr is the eth. addr */
int flags ;
int group ;
} ;
static struct bdg_softc **ifp2sc = NULL ;
#if 0 /* new code using ifp2sc */
#define SAMEGROUP(ifp,src) (src == NULL || \
ifp2sc[ifp->if_index]->group == ifp2sc[src->if_index]->group )
#define MUTED(ifp) (ifp2sc[ifp->if_index]->flags & IFF_MUTE)
#define MUTE(ifp) ifp2sc[ifp->if_index]->flags |= IFF_MUTE
#define UNMUTE(ifp) ifp2sc[ifp->if_index]->flags &= ~IFF_MUTE
#else
#define SAMEGROUP(a,b) 1
#define MUTED(ifp) (ifp->if_flags & IFF_MUTE)
#define MUTE(ifp) ifp->if_flags |= IFF_MUTE
#define UNMUTE(ifp) ifp->if_flags &= ~IFF_MUTE
#endif
static int
sysctl_bdg SYSCTL_HANDLER_ARGS
{
int error, oldval = do_bridge ;
error = sysctl_handle_int(oidp,
oidp->oid_arg1, oidp->oid_arg2, req);
printf("called sysctl for bridge name %s arg2 %d val %d->%d\n",
oidp->oid_name, oidp->oid_arg2,
oldval, do_bridge);
if (bdg_table == NULL)
do_bridge = 0 ;
if (oldval != do_bridge) {
flush_table();
}
return error ;
}
SYSCTL_DECL(_net_link_ether);
SYSCTL_PROC(_net_link_ether, OID_AUTO, bridge, CTLTYPE_INT|CTLFLAG_RW,
&do_bridge, 0, &sysctl_bdg, "I", "Bridging");
SYSCTL_INT(_net_link_ether, OID_AUTO, bridge_ipfw, CTLFLAG_RW, &bdg_ipfw,0,"");
#if 1 /* diagnostic vars */
int bdg_in_count = 0 , bdg_in_ticks = 0 , bdg_fw_count = 0, bdg_fw_ticks = 0 ;
SYSCTL_INT(_net_link_ether, OID_AUTO, bdginc, CTLFLAG_RW, &bdg_in_count,0,"");
SYSCTL_INT(_net_link_ether, OID_AUTO, bdgint, CTLFLAG_RW, &bdg_in_ticks,0,"");
SYSCTL_INT(_net_link_ether, OID_AUTO, bdgfwc, CTLFLAG_RW, &bdg_fw_count,0,"");
SYSCTL_INT(_net_link_ether, OID_AUTO, bdgfwt, CTLFLAG_RW, &bdg_fw_ticks,0,"");
#endif
static struct bdg_stats bdg_stats ;
SYSCTL_STRUCT(_net_link_ether, PF_BDG, bdgstats,
CTLFLAG_RD, &bdg_stats , bdg_stats, "bridge statistics");
static int bdg_loops ;
/*
* completely flush the bridge table.
*/
static void
flush_table()
{
int s,i;
if (bdg_table == NULL)
return ;
s = splimp();
for (i=0; i< HASH_SIZE; i++)
bdg_table[i].name= NULL; /* clear table */
splx(s);
}
/*
* called periodically to flush entries etc.
*/
static void
bdg_timeout(void *dummy)
{
struct ifnet *ifp ;
int s ;
static int slowtimer = 0 ;
if (do_bridge) {
static int age_index = 0 ; /* index of table position to age */
int l = age_index + HASH_SIZE/4 ;
/*
* age entries in the forwarding table.
*/
if (l > HASH_SIZE)
l = HASH_SIZE ;
for (; age_index < l ; age_index++)
if (bdg_table[age_index].used)
bdg_table[age_index].used = 0 ;
else if (bdg_table[age_index].name) {
/* printf("xx flushing stale entry %d\n", age_index); */
bdg_table[age_index].name = NULL ;
}
if (age_index >= HASH_SIZE)
age_index = 0 ;
if (--slowtimer <= 0 ) {
slowtimer = 5 ;
for (ifp = ifnet.tqh_first; ifp; ifp = ifp->if_link.tqe_next) {
if (ifp->if_type != IFT_ETHER)
continue ;
if ( 0 == ( ifp->if_flags & IFF_UP) ) {
s = splimp();
if_up(ifp);
splx(s);
}
if ( 0 == ( ifp->if_flags & IFF_PROMISC) ) {
int ret ;
s = splimp();
ret = ifpromisc(ifp, 1);
splx(s);
printf(">> now %s%d flags 0x%x promisc %d\n",
ifp->if_name, ifp->if_unit,
ifp->if_flags, ret);
}
if (MUTED(ifp)) {
printf(">> unmuting %s%d\n", ifp->if_name, ifp->if_unit);
UNMUTE(ifp) ;
}
}
bdg_loops = 0 ;
}
}
timeout(bdg_timeout, (void *)0, 2*hz );
}
/*
* local MAC addresses are held in a small array. This makes comparisons
* much faster.
*/
unsigned char bdg_addresses[6*BDG_MAX_PORTS];
int bdg_ports ;
/*
* initialization of bridge code.
*/
static void
bdginit(dummy)
void *dummy;
{
int i ;
struct ifnet *ifp;
struct arpcom *ac ;
u_char *eth_addr ;
/*
* initialization of bridge code
*/
if (bdg_table == NULL)
bdg_table = (struct hash_table *)
malloc(HASH_SIZE * sizeof(struct hash_table),
M_IFADDR, M_WAITOK);
flush_table();
ifp2sc = malloc(if_index * sizeof(struct bdg_softc *), M_IFADDR, M_WAITOK );
bzero(ifp2sc, if_index * sizeof(struct bdg_softc *) );
bzero(&bdg_stats, sizeof(bdg_stats) );
bdg_ports = 0 ;
eth_addr = bdg_addresses ;
printf("BRIDGE 981214, have %d interfaces\n", if_index);
for (i = 0 , ifp = ifnet.tqh_first ; i < if_index ;
i++, ifp = ifp->if_link.tqe_next)
if (ifp->if_type == IFT_ETHER) { /* ethernet ? */
ac = (struct arpcom *)ifp;
sprintf(bdg_stats.s[ifp->if_index].name,
"%s%d", ifp->if_name, ifp->if_unit);
printf("-- index %d %s type %d phy %d addrl %d addr %6D\n",
ifp->if_index,
bdg_stats.s[ifp->if_index].name,
(int)ifp->if_type, (int) ifp->if_physical,
(int)ifp->if_addrlen,
ac->ac_enaddr, "." );
bcopy(ac->ac_enaddr, eth_addr, 6);
eth_addr += 6 ;
ifp2sc[bdg_ports] = malloc(sizeof(struct bdg_softc),
M_IFADDR, M_WAITOK );
ifp2sc[bdg_ports]->ifp = ifp ;
ifp2sc[bdg_ports]->flags = 0 ;
ifp2sc[bdg_ports]->group = 0 ;
bdg_ports ++ ;
}
bdg_timeout(0);
do_bridge=0;
}
/*
* bridge_in() is invoked to perform bridging decision on input packets.
* On Input:
* m packet to be bridged. The mbuf need not to hold the
* whole packet, only the first 14 bytes suffice. We
* assume them to be contiguous. No alignment assumptions
* because they are not a problem on i386 class machines.
*
* On Return: destination of packet, one of
* BDG_BCAST broadcast
* BDG_MCAST multicast
* BDG_LOCAL is only for a local address (do not forward)
* BDG_DROP drop the packet
* ifp ifp of the destination interface.
*
* Forwarding is not done directly to give a chance to some drivers
* to fetch more of the packet, or simply drop it completely.
*/
struct ifnet *
bridge_in(struct mbuf *m)
{
int index;
struct ifnet *ifp = m->m_pkthdr.rcvif, *dst , *old ;
int dropit = MUTED(ifp) ;
struct ether_header *eh;
eh = mtod(m, struct ether_header *);
/*
* hash the source address
*/
index= HASH_FN(eh->ether_shost);
bdg_table[index].used = 1 ;
old = bdg_table[index].name ;
if ( old ) { /* the entry is valid. */
if (!BDG_MATCH( eh->ether_shost, bdg_table[index].etheraddr) ) {
printf("collision at %d\n", index);
bdg_table[index].name = NULL ;
} else if (old != ifp) {
/*
* found a loop. Either a machine has moved, or there
* is a misconfiguration/reconfiguration of the network.
* First, do not forward this packet!
* Record the relocation anyways; then, if loops persist,
* suspect a reconfiguration and disable forwarding
* from the old interface.
*/
bdg_table[index].name = ifp ; /* relocate address */
printf("-- loop (%d) %6D to %s%d from %s%d (%s)\n",
bdg_loops, eh->ether_shost, ".",
ifp->if_name, ifp->if_unit,
old->if_name, old->if_unit,
old->if_flags & IFF_MUTE ? "muted":"ignore");
dropit = 1 ;
if ( !MUTED(old) ) {
if (++bdg_loops > 10)
MUTE(old) ;
}
}
}
/*
* now write the source address into the table
*/
if (bdg_table[index].name == NULL) {
DEB(printf("new addr %6D at %d for %s%d\n",
eh->ether_shost, ".", index, ifp->if_name, ifp->if_unit);)
bcopy(eh->ether_shost, bdg_table[index].etheraddr, 6);
bdg_table[index].name = ifp ;
}
dst = bridge_dst_lookup(m);
/* Return values:
* BDG_BCAST, BDG_MCAST, BDG_LOCAL, BDG_UNKNOWN, BDG_DROP, ifp.
* For muted interfaces, the first 3 are changed in BDG_LOCAL,
* and others to BDG_DROP. Also, for incoming packets, ifp is changed
* to BDG_DROP in case ifp == src . These mods are not necessary
* for outgoing packets from ether_output().
*/
BDG_STAT(ifp, BDG_IN);
switch ((int)dst) {
case (int)BDG_BCAST:
case (int)BDG_MCAST:
case (int)BDG_LOCAL:
case (int)BDG_UNKNOWN:
case (int)BDG_DROP:
BDG_STAT(ifp, dst);
break ;
default :
if (dst == ifp || dropit )
BDG_STAT(ifp, BDG_DROP);
else
BDG_STAT(ifp, BDG_FORWARD);
break ;
}
if ( dropit ) {
if (dst == BDG_BCAST || dst == BDG_MCAST || dst == BDG_LOCAL)
return BDG_LOCAL ;
else
return BDG_DROP ;
} else {
return (dst == ifp ? BDG_DROP : dst ) ;
}
}
/*
* Forward to dst, excluding src port and (if not a single interface)
* muted interfaces. The packet is freed if marked as such
* and not for a local destination.
* A cleaner implementation would be to make bdg_forward()
* always consume the packet, leaving to the caller the task
* to make a copy if it needs it. As it is now, bdg_forward()
* can keep a copy alive in some cases.
*/
int
bdg_forward (struct mbuf **m0, struct ifnet *dst)
{
struct ifnet *src = (*m0)->m_pkthdr.rcvif; /* could be NULL in output */
struct ifnet *ifp ;
int error=0, s ;
int once = 0; /* execute the loop only once */
int canfree = 1 ; /* can free the buf at the end */
struct mbuf *m ;
struct ether_header *eh = mtod(*m0, struct ether_header *); /* XXX */
if (dst == BDG_DROP) { /* this should not happen */
printf("xx bdg_forward for BDG_DROP)\n");
m_freem(*m0) ;
*m0 = NULL ;
return 0;
}
if (dst == BDG_LOCAL) { /* this should not happen as well */
printf("xx ouch, bdg_forward for local pkt\n");
return 0;
}
if (dst == BDG_BCAST || dst == BDG_MCAST || dst == BDG_UNKNOWN) {
ifp = ifnet.tqh_first ;
once = 0 ;
if (dst != BDG_UNKNOWN)
canfree = 0 ;
} else {
ifp = dst ;
once = 1 ; /* and also canfree */
}
#ifdef IPFIREWALL
/*
* do filtering in a very similar way to what is done
* in ip_output. Only for IP packets, and only pass/fail/dummynet
* is supported. The tricky thing is to make sure that enough of
* the packet (basically, Eth+IP+TCP/UDP headers) is contiguous
* so that calls to m_pullup in ip_fw_chk will not kill the
* ethernet header.
*/
if (ip_fw_chk_ptr) {
u_int16_t dummy ;
struct ip_fw_chain *rule;
int off;
m = *m0 ;
if (m->m_type == MT_DUMMYNET) {
/*
* the packet was already tagged, so part of the
* processing was already done, and we need to go down.
*/
rule = (struct ip_fw_chain *)(m->m_data) ;
(*m0) = m->m_next ;
FREE(m, M_IPFW);
m = *m0 ;
src = m->m_pkthdr.rcvif; /* could be NULL in output */
eh = mtod(m, struct ether_header *); /* XXX */
canfree = 1 ; /* for sure, a copy is not needed later. */
goto forward; /* HACK! */
} else
rule = NULL ;
if (bdg_ipfw == 0)
goto forward ;
if (src == NULL)
goto forward ; /* do not apply to packets from ether_output */
if (canfree == 0 ) /* need to make a copy */
m = m_copypacket(*m0, M_DONTWAIT);
if (m == NULL) {
/* fail... */
return 0 ;
}
dummy = 0 ;
off= (*ip_fw_chk_ptr)(NULL, 0, src, &dummy, &m, &rule, NULL /*next hop */ ) ;
if (m == NULL) { /* pkt discarded by firewall */
printf("-- bdg: firewall discarded pkt\n");
if (canfree)
*m0 = NULL ;
return 0 ;
}
if (off == 0) {
if (canfree == 0)
m_freem(m);
goto forward ;
}
#ifdef DUMMYNET
if (off & 0x10000) {
/*
* pass the pkt to dummynet. Need to include m, dst, rule.
* Dummynet consumes the packet in all cases.
*/
dummynet_io((off & 0xffff), DN_TO_BDG_FWD, m, dst, NULL, 0, rule);
if (canfree) /* dummynet has consumed the original one */
*m0 = NULL ;
return 0 ;
}
#endif
/* if none of the above matches, we have to drop the pkt */
printf("-- bdg: fw: drop\n");
if (m)
m_freem(m);
if (canfree && m != *m0) {
m_freem(*m0);
*m0 = NULL ;
}
return 0 ;
}
forward:
#endif /* COMPAT_IPFW */
if (canfree && once)
m = *m0 ;
else
m = NULL ;
for ( ; ifp ; ifp = ifp->if_link.tqe_next ) {
if (ifp != src && ifp->if_type == IFT_ETHER &&
(ifp->if_flags & (IFF_UP|IFF_RUNNING)) == (IFF_UP|IFF_RUNNING) &&
SAMEGROUP(ifp, src) && !MUTED(ifp) ) {
if (m == NULL) { /* do i need to make a copy ? */
if (canfree && ifp->if_link.tqe_next == NULL) /* last one! */
m = *m0 ;
else /* on a P5-90, m_packetcopy takes 540 ticks */
m = m_copypacket(*m0, M_DONTWAIT);
if (m == NULL) {
printf("bdg_forward: sorry, m_copy failed!\n");
return ENOBUFS ;
}
}
/*
* execute last part of ether_output.
*/
s = splimp();
/*
* Queue message on interface, and start output if interface
* not yet active.
*/
if (IF_QFULL(&ifp->if_snd)) {
IF_DROP(&ifp->if_snd);
MUTE(ifp); /* good measure... */
splx(s);
error = ENOBUFS ;
} else {
ifp->if_obytes += m->m_pkthdr.len ;
if (m->m_flags & M_MCAST)
ifp->if_omcasts++;
IF_ENQUEUE(&ifp->if_snd, m);
if ((ifp->if_flags & IFF_OACTIVE) == 0)
(*ifp->if_start)(ifp);
splx(s);
if (m == *m0)
*m0 = NULL ; /* the packet is gone... */
m = NULL ;
}
BDG_STAT(ifp, BDG_OUT);
}
if (once)
break ;
}
/* cleanup any mbuf leftover. */
if (m)
m_freem(m);
if (m == *m0)
*m0 = NULL ;
if (canfree && *m0) {
m_freem(*m0);
*m0 = NULL ;
}
return error ;
}
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