• kristoff@infosec.pub
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      4 months ago

      Concerning linux, yesterday I was watching this video on computerphile on the crowdstrike incident. https://www.youtube.com/watch?v=rlaNMJeA1EA (*)

      What is interesting is the comment made in the video on how chromebooks do software upgrades with dual “OS” disk-partitions and the ability to rollback to the previous OS-partition.

      Question: is something like this also possible on one of the major linux distros? (debian, ubuntu, rocky, …) What would be the procedure to do this kind of “dual partition” system-upgrade?

      (*) a great video that explained some of the technical details in a very clear way, including some very interesting ‘lessons learned’ and "what if"s If you ever need to explain crowdstrike to your manager, this video is a good start.

      • Unmapped@lemmy.ml
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        4 months ago

        If I’m understanding the question right. This is what Immutable Linux distros do. Such as Nixos, fedora silver blue, and vanilla os.

        I use nixos myself. But its quite different then most distros. The way you config it and install packages. For the better in my opinion.

        Something like silverblue works pretty much the same as normal Fedora except you can’t install packages like you normally would. Because the system files can’t be edited. You mostly use flatpak for everything. Except the system updates. Which you have to reboot to switch to the new updated image. But past images are saved so you can rollback if needed.

        From what I understand Chromebook os is a Immutable Linux distro same as the ones I mentioned. Just with Google with built in.

        Edit: Also there is a file system you can use. A alternative to ext4. I think its Btrfs. I never tried it. But it let’s you take snapshots that you can restore to. That’s not just system files but everything. And pretty sure you can use it with a disto like arch. I think that’s how snapshots work. But as I said I never actually tried it out.

        • kristoff@infosec.pub
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          4 months ago

          Yes, that was indeed the question.

          If I read it correct, you need a specialised distro for this. You cannot do this on a off-the-shelf Debian or Ubuntu?

          I’ll do some searching on ‘unmutable Linux’. Thanks for the (very quick) answer! 😀

          • Unmapped@lemmy.ml
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            4 months ago

            There is a file system you can use. A alternative to ext4. I think its Btrfs. I never tried it. But it let’s you take snapshots that you can restore to. That’s not just system files but everything. And pretty sure you can use it with a disto like arch and Debian. I think that’s how snapshots work. But as I said I never actually tried it out.

            • kristoff@infosec.pub
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              4 months ago

              just watched some videos on btrfs. Looks interesting indeed. I will look into it and perhaps do a test-installation and see how it goes.

              Thanks for the info

          • tetris11@lemmy.ml
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            4 months ago

            I think the answers given here don’t quite fit the question.

            Android and Windows have dedicated recovery partitions sectioned off on the disk that the OS never boots to and does not interact with during normal system operation.

            If something goes wrong with the OS, then a signal is sent to the BIOS or other non-OS system to “hey, recover from this partition”.

            Btrfs, NixOS, Guix, and other immutable (file-)systems, implement this via having a file system hierarchy protected by various permissions and softlinks to create a checkpoint of sorts, which is managed by a dedicated service that runs with the OS during normal system operation.

            The drawback of these systems is that if something does go wrong with the OS, it cannot fallback to the BIOS to save it. The OS has to somehow signal to itself that it needs to restore from an earlier checkpoint.

            • kristoff@infosec.pub
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              4 months ago

              Just watched some videos on btrfs. I start to understand the conceps. Perhaps I should also look into how exactly

              On windows and the “recovery partion”. I guess what you say is that it should always be possiblity to boot in some kind of system, but it will not happen automatically as there is no way for a system to detect that the system completely hangs.

              Thinking about it. It kind of strange. Embedded systems have watchdog interrupts that get fired if the system hangs (i.e. if it does not provide a “yes, I still live” signal every “x” milliseconds). Does a PC not have something similar?