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have whonixcheck look out for timekeeping watchdog kernel messages
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Description

This...

[ 2743.843690] timekeeping watchdog: Marking clocksource 'tsc' as unstable, because the skew is too large:

... or similar it could look in dmesg.

whonixcheck or whonixcheck --verbose should add a test for that?

It could dmesg for "timekeeping watchdog" and if detected, show a warning.

Kernel messages wrt timekeeping can indicate issues which generate lots of confusion, inconvenience and even time related fingerprinting issues. See https://github.com/QubesOS/qubes-issues/issues/1779 (new information to be added there soon). Which took a while to debug.

Implementation details:

  • whonixcheck runs as user user. /var/log/kern.log is owned by group adm. So whonixcheck has no access to it. To avoid adding user user to group adm, dmesg gets used instead, which [strangely but never mind] is accessible as standard user.
  • dmesg has the added advantage, that it only shows kernel messages since last reboot. So it would not show any messages that may have occurred much earlier that were fixed by kernel or virtualizer upgrades.

Details

Impact
Normal

Event Timeline

Patrick created this task.Mar 21 2016, 1:27 PM

Good idea.

Also I wonder is it possible to mark tsc back as stable, for example after fixing time after resume.

Patrick edited projects, added Whonix 13; removed Whonix 14.Mar 21 2016, 3:05 PM
Patrick changed the task status from Open to Review.Mar 21 2016, 3:16 PM
look out for timekeeping watchdog kernel messages

Kernel messages wrt timekeeping can indicate issues which generate lots of
confusion, inconvenience and even time related fingerprinting issues. See
https://github.com/QubesOS/qubes-issues/issues/1779 (new information to be
added there soon). Which took a while to debug.

https://phabricator.whonix.org/T480

https://github.com/Whonix/whonixcheck/commit/acf19620fc68f0b6c7b29cab9669a6cb5e7e9877

run check_kernel_messages test:
https://github.com/Whonix/whonixcheck/commit/1049109a01bcf997a193265abb22e122b324463e

Patrick added a subscriber: bnvk.Mar 21 2016, 3:21 PM

In future, whonixcheck will show the following message.

[WARNING] [whonixcheck] Check Kernel Messages Test Result: Remarkable kernel message found using dmesg.
[ 2743.843690] timekeeping watchdog: Marking clocksource 'tsc' as unstable, because the skew is too large:

Yes, violates most Qubes usability advice. Keeps the user left with a cryptic message and stranded. Not too useful. But at this stage I have no advice. Therefore open to suggestions and looping in @bnvk.

Patrick closed this task as Resolved.Apr 26 2016, 5:11 PM
Patrick claimed this task.