Keeping Control in the Hands of the User


Various efforts always are underway to implement Secure Boot and to add features that will allow vendors to lock users out of controlling their own systems. In that scenario, users would look helplessly on while their systems refused to boot any kernels but those controlled by the vendors.

The vendors' motivation is clear—if they control the kernel, they can then stream media on that computer without risking copyright infringement by the user. If the vendor doesn't control the system, the user might always have some secret piece of software ready to catch and store any streamed media that could then be shared with others who would not pay the media company for the privilege.

Recently, Chen Yu and other developers tried to submit patches to enhance Secure Boot so that when the user hibernated the system, the kernel itself would encrypt its running image. This would appear to be completely unnecessary, since as Pavel Machek pointed out, there is already uswsusp (userspace software suspend), which encrypts the running image before suspending the system. As Pavel said, the only difference was that uswusp ran in userspace and not kernel space.

Perhaps in an effort to draw Chen into admitting the deeper motives behind the patch submission, Pavel asked Chen to elucidate exactly what security hole his patches addressed and how they would deal with them. Pavel would ask that question over and over again before the end of the discussion, and he would not receive an answer.

Chen offered a variety of justifications for the patch, including letting users do less work, but none of them answered the fundamental question: why was this patch needed as a security enhancement in the first place? And eventually, Pavel called it like he saw it. He said, "Purpose here is to prevent the user from reading/modifying kernel memory content on machine he owns. Strange as it may sound, that is what 'secure' boot requires (and what Disney wants)."

The discussion ended inconclusively, but not utterly. It's clear that Pavel, and a group of core kernel developers including Linus Torvalds, will continue to guard against allowing vendors to control user systems. This seems to be one of the fundamental values of the Linux kernel—to prevent the reemergence of the kind of situation we had in the 1980s, where vendors had ultimate control over virtually all software, while users were at the mercy of business decisions they didn't agree with but could do nothing about.

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Zack Brown is a tech journalist at Linux Journal and Linux Magazine, and is a former author of the "Kernel Traffic" weekly newsletter and the "Learn Plover" stenographic typing tutorials. He first installed Slackware Linux in 1993 on his 386 with 8 megs of RAM and had his mind permanently blown by the Open Source community. He is the inventor of the Crumble pure strategy board game, which you can make yourself with a few pieces of cardboard. He also enjoys writing fiction, attempting animation, reforming Labanotation, designing and sewing his own clothes, learning French and spending time with friends'n'family.

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