Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
On Mon, 1 Feb 2016 19:35:35 + Tomasz Kramkowski wrote: > On Mon, Feb 01, 2016 at 11:11:14AM -0600, Doug Newgard wrote: > > On Mon, 01 Feb 2016 22:27:01 +0530 > > Jayesh Badwaik wrote: > > > > > Hi, > > > > > > I have read the dangers of mounting efivars as writable recently, and I > > > think > > > there should be an entry in the archlinux installation guide and > > > beginner's > > > guide which should say exactly what is said in the warning in [1], and > > > then > > > link to [1] for further instructions. > > > > > > > The "dangers" are only if you do something dumb and your firmware is equally > > dumb. Even then, hopefully the kernel will take care of it. > > https://gist.github.com/mjg59/8d9d494da56fbe6d8992 > > Since when does "do something dumb" and "potentially hard brick your > motherboard" become synonymous when speaking in terms of computers? I never said it shouldn't be dealt with, I'm just saying all of the coverage is really overblown. It's a very obscure set of circumstances that leads to this, and it appears will be handled in the kernel. Let's move on now.
Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
On 1 February 2016 at 23:29, Leonid Isaev wrote: > > Also, how can you brick a machine by simply zeroing the harddrive? > > You can't (well, someone can probably think of a contrived situation where you could, there's always someone, but generally speaking). The problem is with removing certain UEFI variables in buggy UEFI implementations (which are all too common). But in this case (with buggy UEFI implementation) a simple rm -rf of the wrong directory can brick your motherboard. -- Maarten
Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
Sebastiaan Lokhorst wrote: > 2016-02-01 23:29 GMT+01:00 Leonid Isaev : > >> On Mon, Feb 01, 2016 at 01:40:54PM -0800, Kyle Terrien wrote: >>> Tomasz Kramkowski wrote: >>> * Use legacy BIOS. There is nothing wrong with it. >> Exactly, I really don't understand this interest to UEFI (and don't mention >> secureboot). >> > > Many new (OEM) machines do not support legacy BIOS. And this is what is so obnoxious/stupid about the whole situation. In their infinite wisdom, hardware manufacturers are writing broken implementations of an over-engineered system with no way to fallback to the tried/true system that has been around for decades. And when problems are discovered, it is too late. The systems are in production, and it is much easier to blame the consumer for uninstalling Windows than to admit there are millions of buggy boards in the wild. I really hope some sanity will return to the world of pre-boot. --Kyle signature.asc Description: OpenPGP digital signature
Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
2016-02-01 23:29 GMT+01:00 Leonid Isaev : > On Mon, Feb 01, 2016 at 01:40:54PM -0800, Kyle Terrien wrote: > > Tomasz Kramkowski wrote: > > * Use legacy BIOS. There is nothing wrong with it. > Exactly, I really don't understand this interest to UEFI (and don't mention > secureboot). > Many new (OEM) machines do not support legacy BIOS.
Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
On Mon, Feb 01, 2016 at 01:40:54PM -0800, Kyle Terrien wrote: > Tomasz Kramkowski wrote: > > Since when does "do something dumb" and "potentially hard brick your > > motherboard" become synonymous when speaking in terms of computers? > > > > There's doing something dumb (by accident or otherwise) and then there's > > bricking your motherboard, people make accidents all the time but since > > modern day computers are quite nice and rugged, the only losses are data > > losses. > * Use legacy BIOS. There is nothing wrong with it. Exactly, I really don't understand this interest to UEFI (and don't mention secureboot). Also, how can you brick a machine by simply zeroing the harddrive? Cheers, -- Leonid Isaev GPG fingerprints: DA92 034D B4A8 EC51 7EA6 20DF 9291 EE8A 043C B8C4 C0DF 20D0 C075 C3F1 E1BE 775A A7AE F6CB 164B 5A6D
Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
Maarten de Vries wrote: > On 1 February 2016 at 23:29, Leonid Isaev > wrote: > >> >> Also, how can you brick a machine by simply zeroing the harddrive? >> >> > You can't (well, someone can probably think of a contrived situation where > you could, there's always someone, but generally speaking). The problem is > with removing certain UEFI variables in buggy UEFI implementations (which > are all too common). But in this case (with buggy UEFI implementation) a > simple rm -rf of the wrong directory can brick your motherboard. > > -- Maarten Interesting sidenote: In Android, all the system-level stuff is segregated to /system, which is mounted as ro by default. This is just another layer of security. --Kyle signature.asc Description: OpenPGP digital signature
Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
Am 01.02.2016 um 20:35 schrieb Tomasz Kramkowski: > The newbies this change is aimed for are exactly the sorts of people who > might unwittingly rm -rf /. Arch Linux is not aimed at newbies. There's been lots of panic over this issue, yet it took several years of UEFI being in the field for someone to actually trigger it. I guess it will be fixed in the kernel very soon. Until then we can calm down and start panicking - every local privilege escalation bug is worse than this stuff. signature.asc Description: OpenPGP digital signature
Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
Tomasz Kramkowski wrote:
> Since when does "do something dumb" and "potentially hard brick your
> motherboard" become synonymous when speaking in terms of computers?
>
> There's doing something dumb (by accident or otherwise) and then there's
> bricking your motherboard, people make accidents all the time but since
> modern day computers are quite nice and rugged, the only losses are data
> losses.
You would think that a modern day machine is nice and rugged, but with
EFI/UEFI, it isn't. There are way too many moving gears involved.
The preboot environment has one primary task: find a bootable medium and
boot it. Ideally, you should be able to configure it to tell it which
medium to boot from. In the absence of a bootable medium, it should
throw an error. Simple!
This is how things worked before EFI. Sure, getting an OS to load was a
magic trick in the early days ("pulling oneself up by one's
bootstraps"), but today it is a finely honed procedure. There is
nothing broken with this procedure. (After all, it boots!)
Enter EFI and UEFI. From my (somewhat limited) experience with EFI, it
seems like whoever designed it attempted to solve some fringe problem
while creating 5 more problems in its place. Why do OSes need to modify
the boot order entries? Why do some motherboards refuse to fallback to
legacy BIOS? To make things worse, many hardware implementations are
buggy and cannot be fixed (because there are already thousands/millions
of units in production).
So, if you want a modern day computer to be rugged:
* Use legacy BIOS. There is nothing wrong with it.
* Mount efivars (and related stuff) as ro by default. I read the
systemd bug [0], but I still don't understand why so many tools need
to write to it. How often do you need to change motherboard
parameters after you get an OS set up? At that point, POST should be
"find a device and boot it".
> I might shed a few tears over the loss of some not-backed up data, but I
> would be quite a bit more pissed off if I lost a valuable and expensive
> piece of hardware (granted, it would have to have a misconfigured and
> shitty EFI, but since when is "being misconfigured and shitty" a rare
> occurance?).
I wish I could answer the philosophical question of whether rm should be
able to brick hardware. I suggest someone mail Brian Kernighan, Robert
Pike, or Ken Thompson. I would be really curious to hear what they
think about this efivars thing.
--Kyle
[0]: https://github.com/systemd/systemd/issues/2402
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Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
On Mon, Feb 01, 2016 at 11:11:14AM -0600, Doug Newgard wrote: > On Mon, 01 Feb 2016 22:27:01 +0530 > Jayesh Badwaik wrote: > > > Hi, > > > > I have read the dangers of mounting efivars as writable recently, and I > > think > > there should be an entry in the archlinux installation guide and beginner's > > guide which should say exactly what is said in the warning in [1], and then > > link to [1] for further instructions. > > > > The "dangers" are only if you do something dumb and your firmware is equally > dumb. Even then, hopefully the kernel will take care of it. > https://gist.github.com/mjg59/8d9d494da56fbe6d8992 Since when does "do something dumb" and "potentially hard brick your motherboard" become synonymous when speaking in terms of computers? There's doing something dumb (by accident or otherwise) and then there's bricking your motherboard, people make accidents all the time but since modern day computers are quite nice and rugged, the only losses are data losses. I might shed a few tears over the loss of some not-backed up data, but I would be quite a bit more pissed off if I lost a valuable and expensive piece of hardware (granted, it would have to have a misconfigured and shitty EFI, but since when is "being misconfigured and shitty" a rare occurance?). The newbies this change is aimed for are exactly the sorts of people who might unwittingly rm -rf /. -- Tomasz Kramkowski | GPG: 40B037BA0A5B8680 | Web: https://the-tk.com/ signature.asc Description: PGP signature
Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
On Mon, 01 Feb 2016 22:27:01 +0530 Jayesh Badwaik wrote: > Hi, > > I have read the dangers of mounting efivars as writable recently, and I think > there should be an entry in the archlinux installation guide and beginner's > guide which should say exactly what is said in the warning in [1], and then > link to [1] for further instructions. > The "dangers" are only if you do something dumb and your firmware is equally dumb. Even then, hopefully the kernel will take care of it. https://gist.github.com/mjg59/8d9d494da56fbe6d8992
Re: [arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
On February 1, 2016 11:57:01 AM EST, Jayesh Badwaik wrote: >Hi, > >I have read the dangers of mounting efivars as writable recently, and I >think >there should be an entry in the archlinux installation guide and >beginner's >guide which should say exactly what is said in the warning in [1], and >then >link to [1] for further instructions. Well, that's why it's a wiki. Make an account, then go ahead and make that change. --Sean
[arch-general] Instructions to mount efivars as readonly should be linked to in Beginner's Guide
Hi, I have read the dangers of mounting efivars as writable recently, and I think there should be an entry in the archlinux installation guide and beginner's guide which should say exactly what is said in the warning in [1], and then link to [1] for further instructions. -- Cheers Jayesh Badwaik [1] https://wiki.archlinux.org/index.php/ Unified_Extensible_Firmware_Interface#Mount_efivarfs
