Can someone explain to me the whole situation regarding this new vulnerability, phone idling, auto reboot and new auto-reboot implementation?
And what's the easiest solution? Rebooting my phone once in a while? Or do I have to do nothing with this new implementation?
There isn't any vulnerability with the phone idling. You're missing the purpose of the auto-reboot feature. It exists for getting the device back at rest when it hasn't been successfully unlocked for a certain amount of time. This puts a limit on how long attackers have to try to exploit the device while the user is still logged in, since it's going to reboot automatically if it's not successfully unlocked soon.
The default timer was reduced from 72 hours to 18 hours, to provide more security with little impact on usability since most users unlock their phone at least once within 18 hours. If you want a different value, you can change it. The change from 72 to 18 hours only changed it for users who have not chosen a value themselves. If users chose 72 hours themselves, they'll still have it set to 72 hours. The implementation was also improved to prevent bypassing it by triggering system process crashes. It's now implemented in init and init crashing triggers a reboot via kernel panic so that's ruled out.
Thanks for the explanation.
Maybe silly question, but does auto reboot still allow the clock to work? (I.e. alarm when the device is not unlocked) Does it have to be the system clock?
missing-root The alarm will work. You need to make sure to set it in the owner profile, not a secondary profile. Also, if you've set a custom sound, it might default to the default sound (because it doesn't have access to the custom ringtone in BFU, but rather only a select few default ones), or it may not go off at all, someone should test that.
It is not a matter of it being a system app, but rather an app implementing direct boot. Google's clock app should implement direct boot support and work fine in BFU. Other apps may not implement direct boot support, in which case they won't.
One point makes me worry (well, not really worry but my english is not precise enough) : when the phone automatically reboots, you loose the network (calls and data) connexions until at least you type the SIM PIN. And you might not be aware of that. Might a notification or whatever alarm be set up at reboot, in order to warn you that your phone is at the moment, until full restart, a kind of a brick in your pocket.
I can confirm new-clock works when locked!
Eirikr70 SIM PIN doesn't affect alarms from going through, but it will affect carrier calls.
matchboxbananasynergy I meant another point : you can expect a call and and not know that you have been switched off the grid.
Eirikr70 I meant another point : you can expect a call and and not know that you have been switched off the grid.
I think the intention of the auto-reboot timer is for it to be set to an interval long enough that it reboots only if you have been involuntarily separated from your phone. So if you, personally, would plausibly have your phone safely with you for 18 hours without unlocking it, you might choose an auto-reboot interval longer than 18 hours.
GrapheneOS just want to confirm
Does this mean when an attacker overheats the device, it will crash and do auto reboot to bfu now?
Does this also mean that the fastboot mode from wasted also goes to bfu?
Will Auto Reboot delete any data, or is it more of a reset?
No. It just means your phone will shutdown and restart. Result is as if you shutdown & restarted, but have not yet logged in.
Probably9857 Thank you! And thanks for the quick response!
