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epair(4): make sure we do not duplicate MAC addresses

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in case of reused if_index.

PR:		229957
Tested by:	O. Hartmann <ohartmann@walstatt.org>
Approved by:	avg (mentor)
This commit is contained in:
Eugene Grosbein 2018-07-23 07:11:58 +00:00
parent afe7cf8749
commit 804771f553
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=336628
1 changed files with 13 additions and 2 deletions
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15
sys/net/if_epair.c
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@ -107,6 +107,7 @@ static int epair_clone_create(struct if_clone *, char *, size_t, caddr_t);
static int epair_clone_destroy(struct if_clone *, struct ifnet *);
static const char epairname[] = "epair";
static unsigned int next_index = 0;
/* Netisr related definitions and sysctl. */
static struct netisr_handler epair_nh = {
@ -843,12 +844,22 @@ epair_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
/*
* Calculate the etheraddr hashing the hostid and the
* interface index. The result would be hopefully unique
* interface index. The result would be hopefully unique.
* Note that the "a" component of an epair instance may get moved
* to a different VNET after creation. In that case its index
* will be freed and the index can get reused by new epair instance.
* Make sure we do not create same etheraddr again.
*/
getcredhostid(curthread->td_ucred, (unsigned long *)&hostid);
if (hostid == 0)
arc4rand(&hostid, sizeof(hostid), 0);
key[0] = (uint32_t)ifp->if_index;
if (ifp->if_index > next_index)
next_index = ifp->if_index;
else
next_index++;
key[0] = (uint32_t)next_index;
key[1] = (uint32_t)(hostid & 0xffffffff);
key[2] = (uint32_t)((hostid >> 32) & 0xfffffffff);
hash = jenkins_hash32(key, 3, 0);