The Computer Mystery Revealed

Description

The whole point of Secure Boot is to prevent malware from gaining control of the computer. Of course, the ability to use MOKs creates some risk-if you’re tricked into enrolling a MOK that was provided to you by a malware author, your computer will become vulnerable to attacks launched by that malware author. Shim is designed to launch GRUB 2, but it can launch other boot loaders, provided they’re named grubx64.efi. Note, however, that most older follow-on boot loaders, such as ELILO, 인터넷 가입방법 (https://skipper-bolton.mdwrite.net/ – https://skipper-bolton.mdwrite.net/maximize-your-online-marketing-possible-with-one-of-these-ideas) won’t honor the Secure Boot settings. Shim keys-Shim may optionally be compiled with its own built-in key, which takes the same form as a Secure Boot key but isn’t registered with the firmware. This step is necessary only if the follow-on boot loader and kernel are not already signed-for instance, if you compiled them yourself. Because some motherboards come with Canonical Secure Boot keys built-in, though, if you’re dual-booting Ubuntu and some other distribution, using the other distribution’s Shim may save you from having to enter Canonical’s MOK, which is a small advantage. Rather than confront them with a zillion choices, though, narrow it down to three or four colors you think are appropriate and then let them choose.
Unfortunately, these goals are at odds with the open source philosophy of freedom and user control of their computers. One is strictly contractual: As described in this blog post by James Bottomley, Microsoft refuses to sign binaries distributed under certain open source licenses, including the GPLv3, which GRUB 2 and rEFInd both use. As of early 2023, I know of two signed boot loaders intended for use with Linux: Fedora’s Shim program (which is also being used by Ubuntu, SUSE, Sabayon, ALT, and others) and the Linux Foundation’s “PreLoader.” As I write, several signed versions of Shim are available, as is at least one signed version of PreLoader. In such a case, disabling Secure Boot may be your best bet, at least in the short term as you investigate the cause of the problem. Furthermore, I’ve discovered that some Secure Boot implementations are very finicky about their signed binaries, and will reject some binaries built with at least some versions of GNU-EFI. Therefore, when booting with Secure Boot active, Fedora 18 and later, Ubuntu 16.04 and later, and probably other distributions restrict actions that some Linux users take for granted.
Thus, a Secure Boot solution for Linux must balance these two goals. Thus, you may not be able to boot a Shim that was released prior to mid- or late-2020. Thus, if you try Shim but run into Secure Boot violations when launching it, try another binary – ideally, the newest you can find. As a practical matter, if you want to use Shim, you have two choices: You can run a distribution that provides its own signed version of Shim, such as Fedora 18 or later or Ubuntu 12.10 or later; or you can run a signed version from such a distribution or from another source, add your own MOK, and sign whatever binaries you like. Fedora designed its Shim program to do just that. Some require professional installation — a representative will visit your dad’s yard and program the lawnmower so that it stays within the property perimeter. Treat shim.efi or shimx64.efi like any other boot loader, as described in the EFI Boot Loader Installation page. MOKs-A Machine Owner Key (MOK) is a type of key that a user generates and uses to sign an EFI binary. 5. If necessary, sign the follow-on boot loader, as well as any unsigned kernel you want to launch.
Almost all Fortune 1,000 businesses, as well as many small businesses, use airlines extensively. I describe its use shortly. For instance, Linux kernel modules must be signed, which complicates use of third-party kernel drivers, such as Nvidia’s and AMD/ATI’s proprietary video drivers. You may need to use a Secure Boot-enabled Linux emergency disc, temporarily disable Secure Boot, boot using the Linux Foundation’s PreLoader, or do the work from Windows. PreLoader, however, has been largely abandoned, so it’s mainly of historical interest. We all know, however, that it’s what’s on the outside that counts. Using a boot loader signed with Microsoft’s key is the simplest and most direct approach to booting with Secure Boot active; however, it’s also the most limiting approach. More recent kernels may, if Secure Boot is active, also check that they were launched from a boot loader that honors Secure Boot, and shut down if this was not the case. Another reason is practical: A boot loader like GRUB 2 is large and may require rapid replacement in case bugs are found. Secure Boot keys-Shim recognizes the keys that are built into the firmware, or that users create themselves (as described in detail on my next page, Controlling Secure B.