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bridge: Simplify mac address generation

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Unconditionally use ether_gen_addr() to generate bridge mac addresses.  This
function is now less likely to generate duplicate mac addresses across jails.
The old hand rolled hostid based code adds no value.

Reviewed by:	bz
Differential Revision:	https://reviews.freebsd.org/D24432
This commit is contained in:
Kristof Provost 2020-04-18 08:00:58 +00:00
parent 3f8bc99c4c
commit fac24ad7f0
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=360069
1 changed files with 3 additions and 39 deletions
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42
sys/net/if_bridge.c
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@ -676,10 +676,8 @@ SYSCTL_PROC(_net_link_bridge, OID_AUTO, ipfw,
static int
bridge_clone_create(struct if_clone *ifc, int unit, caddr_t params)
{
struct bridge_softc *sc, *sc2;
struct ifnet *bifp, *ifp;
int fb, retry;
unsigned long hostid;
struct bridge_softc *sc;
struct ifnet *ifp;
sc = malloc(sizeof(*sc), M_DEVBUF, M_WAITOK|M_ZERO);
ifp = sc->sc_ifp = if_alloc(IFT_ETHER);
@ -709,41 +707,7 @@ bridge_clone_create(struct if_clone *ifc, int unit, caddr_t params)
ifp->if_init = bridge_init;
ifp->if_type = IFT_BRIDGE;
/*
* Generate an ethernet address with a locally administered address.
*
* Since we are using random ethernet addresses for the bridge, it is
* possible that we might have address collisions, so make sure that
* this hardware address isn't already in use on another bridge.
* The first try uses the hostid and falls back to arc4rand().
*/
fb = 0;
getcredhostid(curthread->td_ucred, &hostid);
do {
if (fb || hostid == 0) {
ether_gen_addr(ifp, &sc->sc_defaddr);
} else {
sc->sc_defaddr.octet[0] = 0x2;
sc->sc_defaddr.octet[1] = (hostid >> 24) & 0xff;
sc->sc_defaddr.octet[2] = (hostid >> 16) & 0xff;
sc->sc_defaddr.octet[3] = (hostid >> 8 ) & 0xff;
sc->sc_defaddr.octet[4] = hostid & 0xff;
sc->sc_defaddr.octet[5] = ifp->if_dunit & 0xff;
}
fb = 1;
retry = 0;
BRIDGE_LIST_LOCK();
LIST_FOREACH(sc2, &V_bridge_list, sc_list) {
bifp = sc2->sc_ifp;
if (memcmp(sc->sc_defaddr.octet,
IF_LLADDR(bifp), ETHER_ADDR_LEN) == 0) {
retry = 1;
break;
}
}
BRIDGE_LIST_UNLOCK();
} while (retry == 1);
ether_gen_addr(ifp, &sc->sc_defaddr);
bstp_attach(&sc->sc_stp, &bridge_ops);
ether_ifattach(ifp, sc->sc_defaddr.octet);