We have been working hard the last several months to stop Restricted Boot, a major threat to user freedom, free software ideals, and free software adoption. Under the guise of security, a computer afflicted with Restricted Boot refuses to boot any operating systems other than the ones the computer distributor has approved in advance. Restricted Boot takes control of the computer away from the user and puts it in the hands of someone else.
To respect user freedom and truly protect user security, computer makers must either provide users a way of disabling such boot restrictions, or provide a sure-fire way that allows the computer user to install a free software operating system of her choice.
Distributors of restricted systems usually appeal to security concerns. They claim that if unapproved software can be used on the machines they sell, malware will run amok. By only allowing software they approve to run, they can protect us.
This claim ignores the fact that we need protection from them. We don’t want a machine that only runs software approved by them -- our computers should always run only software approved by us. We may choose to trust someone else to help us make those approval decisions, but we should never be locked into that relationship by force of technological restriction or law. Software that enforces such restrictions is malware. Companies like Microsoft that push these restrictions also have a terrible track record when it comes to security, which makes their platitudes about restricting us for our own good both hollow and deceitful.
» fsf.org