Re: [gentoo-dev] newsitem: openrc-0.28 mounts efivars read only

[Mike Gilbert]

On Thu, Jul 13, 2017 at 12:45 PM, Mike Gilbert <floppym@g.o> wrote:
> On Thu, Jul 13, 2017 at 10:58 AM, Andrew Savchenko <bircoph@g.o> wrote:
>> On Thu, 13 Jul 2017 10:29:06 -0400 Mike Gilbert wrote:
>>> On Thu, Jul 13, 2017 at 7:35 AM, M. J. Everitt <m.j.everitt@×××.org> wrote:
>>> > On 13/07/17 12:09, Rich Freeman wrote:
>>> >> Presumably you'd only want to remount it if it was mounted ro to
>>> >> start, since it sounds like openrc will be diverging from systemd
>>> >> behavior here.
>>> >>
>>> >> While it seems like a good idea I'm not sure how big an improvement it
>>> >> is in the larger scheme.  We're worried about root accidentially
>>> >> modifying efivars, but we have no safeguards against root writing to
>>> >> /dev/sda, and the latter seems much more likely to cause harm, and is
>>> >> harder to fix.
>>> >>
>>> > In case you weren't aware, Rich, rewriting the efivars actually writes
>>> > to the system BIOS, which renders the computer completely unbootable ..
>>> > not quite the same as erasing the boot sector of your hard disk, where
>>> > you simply plug in another device, and Off you go ...
>>> >
>>>
>>> We are actually talking about protecting people who run something like
>>> rm -rf /sys/firmware/efi/efivars/ as root.
>>>
>>> If you are dumb enough to do something like that, you almost deserve
>>> to spend a couple hundred on a new motherboard.
>>
>> Or just rm -rf /
>> [pedantic]
>> of course with newer rm versions one needs to run:
>> rm -rf --no-preserve-root /
>> or
>> rm -rf /* /.*
>> [/pedantic]
>>
>> But in some scenarios this command is normal. E.g. user installs
>> Gentoo from some live dvd/flash, makes some mistakes, understands
>> that system is broken beyond repair and decides to start over again.
>> If there is no need to recreate filesystem itself or partition
>> layout, running rm -rf / as above is quite reasonable.
>>
>> When running this command user expects to kill the data, but not
>> the hardware. That is my point. I can't call such action dumb.
>>
>> Best regards,
>> Andrew Savchenko
>
> Point taken.
>
> Although, if the user is in the process of installing Gentoo, efivarfs
> is likely to be mounted rw anyway so that the user can install a boot
> loader. Having grub-install perform the remount would minimize this
> small risk I suppose.

s/grub-install/efibootmgr/; grub-install does not update efivarfs
directly, but rather calls efibootmgr to do it.