kern: ether_gen_addr: randomize on default hostuuid, too
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Authored by kevans on Apr 16 2021, 1:16 AM.

Details

Reviewers

kbowling
kp
imp
bz

Group Reviewers

network
manpages

Commits

rG0a7dbddfb0ca: kern: ether_gen_addr: randomize on default hostuuid, too
rG8a206a22654f: kern: ether_gen_addr: randomize on default hostuuid, too
rG2d741f33bd07: kern: ether_gen_addr: randomize on default hostuuid, too

Summary

Currently, this will still hash the default (all zero) hostuuid and
potentially arrive at a MAC address that has a high chance of collision
if another interface of the same name appears in the same broadcast
domain on another host without a hostuuid, e.g., some virtual machine
setups.

Instead of using the default hostuuid, just treat it as a failure and
generate a random LA unicast MAC address.

Diff Detail

Repository

rS FreeBSD src repository - subversion

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Unit

No Test Coverage

Build Status

Buildable 38613
Build 35502: arc lint + arc unit

Event Timeline

kevans created this revision.Apr 16 2021, 1:16 AM

Herald added subscribers: melifaro, ae, imp. · View Herald TranscriptApr 16 2021, 1:16 AM

kevans requested review of this revision.Apr 16 2021, 1:16 AM

kevans added a parent revision: D29787: man: document ether_gen_addr(9).

Harbormaster completed remote builds in B38613: Diff 87528.Apr 16 2021, 1:16 AM

imp accepted this revision.Apr 16 2021, 1:27 AM

This revision is now accepted and ready to land.Apr 16 2021, 1:27 AM

kbowling accepted this revision.Apr 16 2021, 1:35 AM

donner added a subscriber: donner.Apr 16 2021, 6:11 AM

donner added inline comments.

sys/net/if_ethersubr.c
1480	return;

kp accepted this revision as: kp.Apr 16 2021, 8:51 AM

LGTM from manpages.

Don't forget to bump .Dd on the man page when committing.

In D29788#668512, @bz wrote:

Don't forget to bump .Dd on the man page when committing.

You took the words right out of my mouth. :)

melifaro added inline comments.Apr 17 2021, 10:31 AM

sys/net/if_ethersubr.c
1476	Maybe it's worth having this logic as a separate function instead of the `goto` block?

kevans added inline comments.Apr 17 2021, 2:39 PM

sys/net/if_ethersubr.c
1476	I'd tend to prefer not... this is really just a failure path, and we shouldn't expose a "random mac address" KPI since we're somewhat trying to reduce the # LA addresses we're randomly generating.