Red Hat engineer renews attack on Windows 8-certified secure boot

A senior Red Hat engineer has lashed back at Microsoft's attempt to downplay concerns that upcoming secure boot features will make it impossible to install Linux on Windows 8 certified systems.

Unified Extensible Firmware Interface (UEFI) specifications are designed to offer faster boot times and improved security over current BIOS ROM systems. The secure boot feature of the specification is designed so that only digitally signed OS loaders will load, a security feature that would prevent the installation of generic copies of Linux or FreeBSD as well as preventing rootkits and other boot-time malware from running.

A digitally signed build of Linux would work, but that would mean persuading OEMs to include the keys. Disabling the feature would allow unsigned code to run. However, it is unclear how many OEMs and firmware vendors will follow this route, which isn't required for Windows 8 certification.

The forthcoming secure boot feature has created a huge row with computer scientists, such as Ross Anderson of Cambridge University (here), and open-source developers who accuse Microsoft of pushing lock-in and decreasing consumer choice. Microsoft responded by saying consumers would continue to control their PC and cited the example of one OEM, Samsung, which is including a "disable secure boot" feature on prototype versions of its tablet PC.

Power play

This response has failed to satisfy critics of the technology. Matthew Garrett, power management and mobile Linux developer at Red Hat, who was among the first to flag up concerns over the technology, said that Microsoft's response fails to address his central point that "Windows 8 certified systems will make it either more difficult or impossible to install alternative operating systems".

Red Hat, he explains, has been working with Linux suppliers, hardware manufacturers and BIOS developers since becoming aware of the issue in early August.

Garrett said that Windows 8 certification requires that hardware ship with UEFI secure boot enabled. A feature allowing secure boot to be disabled – necessary to run Linux and FreeBSD on certified systems – is not required for certification. "We've already been informed by hardware vendors that some hardware will not have this option," Garrett writes in a flow-up blog post to his original critique of the technology.

In addition, Windows 8 certification does not require that the system ship with any keys other than Microsoft's. Such systems will only securely boot Microsoft operating systems.

A system that ships with Microsoft's signing keys and no others will be unable to perform secure boot of any operating system other than Microsoft's," Garrett writes. "No other vendor has the same position of power over the hardware vendors. Red Hat is unable to ensure that every OEM carries their signing key. Nor is Canonical. Nor is Nvidia, or AMD or any other PC component manufacturer."

Neither of the two options – the first being to get OEMs to include keys for a digitally signed copy of a particular build of Linux and the second being allowing users to disable secure boot – look likely in most circumstances. The upshot of this, as things stand, is that Linux fans will only be able to run the alternative operating system on a small minority of Windows 8-certified hardware.

Control

But the issue goes beyond operating system choices and also affects other modification a user might choose to make to their PC, Garrett argues. He reckons Microsoft is pushing control of what can or can't be done on a PC away from consumers towards hardware manufacturers.

"Microsoft claims that the customer is in control of their PC," he writes. "That's true, if by 'customer' they mean 'hardware manufacturer'. The end user is not guaranteed the ability to install extra signing keys in order to securely boot the operating system of their choice. The end user is not guaranteed the ability to disable this functionality. The end user is not guaranteed that their system will include the signing keys that would be required for them to swap their graphics card for one from another vendor, or replace their network card and still be able to netboot, or install a newer SATA controller and have it recognise their hard drive in the firmware. The end user is no longer in control of their PC."

Garrett isn't opposed to secure boot or UEFI as such but the way Microsoft is "misusing" the technology to "gain tighter control" over the desktop operating system market it already dominates.

"Microsoft's rebuttal is entirely factually accurate," Garrett writes. "But it's also misleading. The truth is that Microsoft's move removes control from the end user and places it in the hands of Microsoft and the hardware vendors. The truth is that it makes it more difficult to run anything other than Windows. The truth is that UEFI secure boot is a valuable and worthwhile feature that Microsoft are misusing to gain tighter control over the market. And the truth is that Microsoft haven't even attempted to argue otherwise," he concludes. ®

Boot(ing-up) Note

Red Hat has done some testing work with the UEFI Forum, an industry group that is overseeing the development and introduction of the next-generation start-up specification. However this testing work happened before the implications of the secure boot feature became clear, Garrett told El Reg.

We're contributing members of the UEFI forum, which means we have access to the specification drafts and contribute towards the language in them," Garrett told El Reg. "We also typically attend some of the UEFI testing events. While the UEFI specification for secure boot has been public for some time, Microsoft's plans for it only became known very recently. We're still at the point of working out how some of the fine details are going to work. So, yes, while we do some testing with the forum, the last testing event was from before Microsoft let us know they were going to do this." ®