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Running "rm -rf /" Is Now Bricking Linux Systems (phoronix.com)
An anonymous reader writes: For newer systems utilizing UEFI, running rm -rf / is enough to permanently brick your system. While it's a trivial command to run on Linux systems, Windows and other operating systems are also prone to this issue when using UEFI. The problem comes down to UEFI variables being mounted with read/write permissions and when recursively deleting everything, the UEFI variables get wiped too. Systemd developers have rejected mounting the EFI variables as read-only, since there are valid use-cases for writing to them. Mounting them read-only can also break other applications, so for now there is no good solution to avoid potentially bricking your system, but kernel developers are investigating the issue.
Have you tried not running rm -rf /?
Mounting UEFI variables as read only breaks things too. How will you get rid of that problem once you get rid of systemd? Or is everything systemd's fault by default now?
Those who do not learn from commit history are doomed to regress it.
No, I wouldn't expect rm -rf to brick my system. I would expect it to remove everything, and then I'd have to reinstall. I would not expect my computer to become unusable to the point that I couldn't reinstall an OS.
Having come up during the advent of computers, this is PRECISELY why we separated hardware bootstrap firmware from user-accessible code in the first place, and did not make provisions for user-space access to change it. The hardware had to continue to operate and boot regardless of the stupid things users and developers did.
That all went out the window the moment we started with this "update your BIOS from the O/S" bullshit. And now, apparently, "let's give userspace read/write access to the bootstrap firmware willy nilly," which is complete and utter stupidity.
Not that UEFI isn't catastrophically broken, but reading TFA, in this case the real problem seems to be the way it is implemented on some motherboards (TFA mentions "some MSI notebooks" without specifying further). Even if EFI vars are broken, that really shouldn't brick your motherboard unless the motherboard itself is buggy. Makes me wonder if the owners have tried resetting their NVRAM, or if that too is perhaps impossible on these motherboards.
No, he's not an idiot. He's a normal person. Normal people click uninstall and expect their game to be uninstalled, not their OS's GUI. Linux package managers are well overdue for redesign. Making hardware brick able by software is also bad design. Mounting firmware as ordinary rw files, ditto.
This looks like an EFI design bug. Why should EFI allow the OS or any other software brick the system by deleting its variables? Like OO, EFI should allow access to these variables through methods and not directly.
Any changes to the firmware should only be possible by flipping a hardware switch first. Coincidentally, that would also make whole secure boot schmoo obsolete. But we can't have end-consumers control their own computers, can't we?
"To my understanding, you can't boot anymore, at all. If we could simply boot to BIOS and reflash the firmware this wouldn't be such a big issue."
That's entirely too sane. I think you can probably scratch BIOS programming from your list of possible future occupations. You'd have to take a LOT of drugs and stay stoned in order to comply with modern practices
An even better answer would be to try the following concept: A BIOS is a simple and robust, non-writable boot system residing in Read ONLY Memory. BIOSes are small, simple, things that have to be written well since you only get one shot at doing them. Once your device goes into production, you are stuck with whatever the code does.
Note that doesn't preclude insane complexity in the layers of code that are loaded by the BIOS. Modern programming practices can live on .... just not in the lowest level of boot code.
BTW, why do folks think that a design that allows users to inadvertently irretrievably cripple hardware can possibly be secure? If you can accidentally brick the damn thing from a keyboard, what do you think hostile agents can do once they've penetrated your system?
You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
Is there anything that prevents code that really needs to write the UEFI from unmounting a default read/only file system and remounting it as read/write? Have the crazies deprecated mount and umount? And really now, how much need to write UEFI is there likely to be in any configuration not designed by complete lunatics?
You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
The problem is that UEFI missed the KISS principal and is basically an OS itself. In that way, the principals (not necessarily the implementation) of the original PC BIOS are actually a much better target for for an OS bootloader. See uboot (which actually probably goes a little to far the in opposite direction because it lacks the ability to run option rom/support 3rd party plug in devices). You complain about BIOS, but you have to understand that the BIOS design evolved from PCs with 8/16 bit processors and a few KB of ram, all the way to 64-bit computers with hundreds of GB of ram, along the way supported thousands of different peripherals. By comparison UEFI is a tiny slice of the modern computing ecosystem, and most non PC devices abandoned UEFI and instead went for simpler boot mechanisms more reminiscent of BIOS (see cellphones, etc).
BTW; UEFI still does POST (in the generic sense, often with POST codes), its also configures PCIe interrupts and the APIC, which is required for ACPI which remains in UEFI as much as it was in BIOS. Only on ARM64 can you get away from UEFI requiring ACPI to be useful, in the form of UEFI/DT. Which makes one question why run UEFI at all instead of uboot/DT which go together better. (just to be clear ARM64 also "supports" UEFI/ACPI).
Great plan until systemd started putting its "unit" files (great non descriptive name eh? its hard to come up with a less descriptive name) in /lib and then overriding them with /run and /etc.