mjg59 | Secure Boot and Restricted Boot.

I gave a presentation at Libreplanet this weekend on the topic of Secure Boot and Restricted Boot. There's a copy of the video here - it should be up on the conference site at some point. It turned out to be excellent timing, in that a group in Spain filed a complaint with the European Commission this morning arguing that Microsoft's imposition of Secure Boot on the x86 client PC market is anticompetitive. I suspect that this is unlikely to succeed (the Commission has already stated that the current implementation appears to conform to EU law), and I fear that it's going to make it harder to fight the real battle we face.

Secure Boot means different things to different people. I think the FSF's definition is a useful one - Secure Boot is any boot validation scheme in which ultimate control is in the hands of the owner of the device, while Restricted Boot is any boot validation scheme in which ultimate control is in the hands of a third party. What Microsoft require for x86 Windows 8 devices falls into the category of Secure Boot - assuming that OEMs conform to Microsoft's requirements, the user must be able to both disable Secure Boot entirely and also leave Secure Boot enabled, but with their own choice of trusted keys and binaries. If the FSF set up a signing service to sign operating systems that met all of their criteria for freeness, Microsoft's requirements would permit an end user to configure their system such that it refused to run non-free software. My system is configured to trust things shipped by Fedora or built locally by me, a decision that I can make because Microsoft require that OEMs support it. Any system that meets Microsoft's requirements is a system that respects the freedom of the computer owner to choose how restrictive their computer's boot policy is.

This isn't to say that it's ideal. The lack of any common UI or key format between hardware vendors makes it difficult for OS vendors to document the steps users must take to assert this freedom. The presence of Microsoft as the only widely trusted key authority leaves people justifiably concerned as to whether Microsoft will be equally aggressive in blacklisting its own products as it will be in blacklisting third party ones. Implementation flaws in a (very) small number of systems have resulted in correctly signed operating systems failing to boot, requiring users to update their firmware before being able to install anything but Windows.

But concentrating on these problems misses the wider point. The x86 market remains one where users are able to run whatever they want, but the x86 market is shrinking. Users are purchasing tablets and other ARM-based ultraportables. Some users are using phones as their primary computing device. In contrast to the x86 market, Microsoft's policies for the ARM market restrict user freedom. Windows Phone and Windows RT devices are required to boot only signed binaries, with no option for the end user to disable the signature validation or install their own keys. While the underlying technology is identical, this differing set of default policies means that Microsoft's ARM implementation is better described as Restricted Boot. The hardware vendors and Microsoft define which software will run on these systems. The owner gets no say.

And, unfortunately, Microsoft aren't alone. Apple, the single biggest vendor in this market, implement effectively identical restrictions. Some Android vendors provide unlockable bootloaders, but others (either through personal preference or at the behest of phone carriers) lock down their platforms. A naive user is likely to end up purchasing a device that will, in the absence of exploited security flaws, refuse to run if any system components are modified. Even in cases where the underlying components are built using free software, there's no guarantee that the user will have the ability to assert any of those freedoms.

Why does this matter? Some of these platforms (notably Windows RT and iOS, but also some Android-based devices) will even refuse to run unsigned applications. Users are unable to write their own software and distribute it to others without agreeing to often onerous restrictions. Users with the misfortune of living in the wrong country may be forbidden from even that opportunity. The vendor may choose to block applications that compete with their own, reducing innovation. The ability to explore and tinker with the components of the system is restricted, making it harder for users to learn how modern operating systems work. If I own a perfectly functional phone that no longer receives vendor updates, I don't even have the option of paying a third party to ensure that I can't be compromised by a malicious website and risk the loss of passwords or financial details. The user is directly harmed by these restrictions.

I won't argue that there are no benefits to curated software ecosystems. I won't even argue against devices shipping with a locked down policy by default. I will strongly argue that the owner of a device should not only have the freedom to choose whether they wish to remain within those locked-down boundaries, but should also have the freedom to impose their own boundaries. There should be no forced choice between freedom and security.

Those who argue against Secure Boot risk depriving us of the freedom to make a personal decision as to who we trust. Those who argue against Secure Boot while ignoring Restricted Boot risk depriving us of even more. The traditional PC market is decreasing in importance. Unless we do anything about it, free software will be limited to a niche group of enthusiasts who've carefully chosen from a small set of devices that respect user freedom. We should have been campaigning against Restricted Boot 10 years ago. Don't delay it even further by fighting against implementations that already respect user freedom.

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Threaded | Top-Level Comments Only

From: (Anonymous)

We *were* campaigning against Restricted Boot 10 years ago, when it went by names like "Palladium" and "Trusted Computing". Some people argue against Secure Boot just because it smells like what those abstract technologies we fought against years ago. Some argue against it because it's a single brand for both FSF's "Secure Boot" and "Restricted Boot" concepts, and it's almost impossible to argue against one and not the other unless your target audience already knows enough of the technical details that you hardly need to argue.

From:

mjg59

Palladium's a somewhat different issue covering a range of different technologies, but fundamentally it never actually prevented you from running your choice of software - it meant that your ability to access certain resources would be limited or prevented. Both Palladium and Restricted Boot are examples of limiting people's abilities to use computers, but I think claiming direct equivalence is misleading.

From: (Anonymous)

"Any system that meets Microsoft's requirements is a system that respects the freedom of the computer owner to choose how restrictive their computer's boot policy is."

And that's the point which you keep to make although you have experienced the complicated problems secure boot introduces and which I don't buy. The problem with your definition of freedom is that you are almost ignoring the prerequisites towards the user. When he chooses to buy a machine coming with windows or just has a windows certification, John Doe does not know about Secure Boot or how to install his own keys, neither is there easily understandable documentation where he could educate himself how to do it, because that way is not standardized. It is a bit like if everybody would be born with handcuffs on and only if you pay a certain amount of money you get released and arguing that in this scenario everybody's freedom is respected and no harm is done, because everybody can remove their handcuffs if they just invest a bit of time.

Just because Secure Boot (the UEFI scheme, not the principle of authenticated boot) is not as bad as other abominations does not mean that we should not fight it, but I agree we should fight restricted boot schemes harder.

From: (Anonymous)

If John Doe is unable to turn off a simple setting in BIOS, can you trust him to be able to change the boot order and install and configure Linux and partition disks without deleting his data?

From: (Anonymous)

Yes, you *were* campaigning against Microsoft. However, when Apple implemented the Palladium spec to the letter, most people folded because they were more anti-Microsoft than pro-freedom and were taken by the shiny stuff. Now it is acceptable to the public to buy locked down devices.

From: (Anonymous)

Trusted computing isn't "restricted boot", even by the FSF's definition above:

Can you completely disable the TPM? Yes
Can you run any software you'd like? Yes

Even if you opt-in:
Can you choose which keys you trust? Yes
Can you choose your root of trust? Yes

Kent Yoder

From: (Anonymous)

As far as I'm concerned, the kerfuffle betwixt "sercure" boot, and "restricted" boot is a digression from the main issue, whether or not users control their own systems, that they have purchased, and hence own. If they own them, then THEY should have all control over how the system is to be configured or behave. I they don't, then they are only RENTING their computer systems. Anything else, is a distraction. So, do we OWN our systems, or do we NOT?

From:

mjg59

If it's Secure Boot, you control the system. If it's Restricted Boot, you don't. You seem to be loudly agreeing.

From: (Anonymous)

Yes. Many systems boot from CD by default. And if it's a new computer John doesn't care about parititoning, most modern linux installers will auto-partition the drive for you.

From: (Anonymous)

I never heard anyone talking about the following:

Say you want to dual-boot Linux and Windows 8

1. If you disable secure boot to be able to run Linux will Windows 8 still boot?

2. If Windows 8 will boot will it play protected content while secure boot is disabled or are all your multimedia purchases from Windows Store or other DRM sources inaccessible until you turn secure boot back on?

3. If you do not disable secure boot, but instead insert your own key will that erase secure key storage by default and thus remove Microsoft's key?

4. How complicated is to sign Linux kernel which you have compiled?

5. How does secure boot affect projects like linux from scratch, Hirens Boot CD, etc?

From:

mjg59

1. If you disable secure boot to be able to run Linux will Windows 8 still boot?

Yes.

2. If Windows 8 will boot will it play protected content while secure boot is disabled

It will.

3. If you do not disable secure boot, but instead insert your own key will that erase secure key storage by default and thus remove Microsoft's key?

Depends on your firmware implementation - some systems only let you install keys by removing all the existing keys. However, you can enrol as many keys as you want to while you're doing that, so you can add your own key *and* Microsoft's key.

4. How complicated is to sign Linux kernel which you have compiled?

Trivial. You just need to use sbsigntool or pesign.

5. How does secure boot affect projects like linux from scratch, Hirens Boot CD, etc?

You'd really have to ask their developers what they think the best approach is.

From: (Anonymous)

Regarding #2, are you absolutely sure?

It is really hard to believe because all the efforts so far being made on locking down user's PCs were done with an intent of stopping piracy.

Regarding #3, what I really don't understand is how would you add Microsoft's key back? Where do you get it?

From:

mjg59

Yes. Secure Boot does nothing to prevent piracy. No secret keys are installed on your system. Microsoft's key is publicly available - you can just copy it out of your key database before wiping it.

From: (Anonymous)

So what is the usefull thing that the secure boot does then?

If Microsoft doesn't care about the integrity of executable files and boot process and allows everything to still work with it disabled, what is the point in having it in the first place?

From:

mjg59

Malware can't disable it, and if your early boot files are modified by malware while it's enabled then your system will refuse to boot until you've fixed it.

From:

kevinkofler.wordpress.com

Except that this is trivially circumvented by the Blue Pill attack, which was already well known when "Secure" Boot was designed. So all security it provides is illusionary. All it does it making it a PITA to evade the default-on restrictions of your freedom on x86 and allowing the same company to implement their hard restrictions on ARM. And Red Hat is even paying money to the signature cartel to support their evil scheme!

From: (Anonymous)

Thank you for your well reasoned explanation, sadly this sort of thinking and analysis has been missing from the debate.

Secure Boot is a good thing, with some implementation problems. Restricted Boot is horrible and should be legislated against

From: (Anonymous)

I have read several posts on the Net which highlight restrictive practices. I said this would happen and it has. Is anyone so blind as cannot see that Microsoft is not a nice company, no, in my opinion they are evil!

Here is just one post from a distressed customer of a Samsung product on which he finds:-
1. Secure boot cannot be switched off.
2. Booting is not possible on neither CD nor USB media

Look for the heading 'APPALLING - AVOID!!!'.
http://www.amazon.co.uk/product-reviews/B009SJCX68

From:

mjg59

Where does that claim the device doesn't let you disable Secure Boot? The other comments clearly say that it does, and also that it can boot from USB and CD.

From:

mjg59

How do you launch blue pill in this scenario?

From: (Anonymous)

We are finding in Ubuntu Forums that a lot of variation by Computer Vendor and model.

Some work just the way they should and dual boot Windows 8 and Ubuntu without any issue.
Some require secure boot and the shim file works to boot Ubuntu.
But some seem to be hard coded to only boot /EFI/Microsoft/Boot/bootmgfw.efi. A work around is the rename shim to the Windows efi file and that works.
And some just do not seem to work at all. Not sure if user issues with all the new settings in UEFI menus or how UEFI is implemented.

From: (Anonymous)

With KVM on a distro signed by Microsoft, or perhaps even on Windows with compromised userspace and a (signed) virtual machine monitor.

Yes, it would flicker impressively at startup.

From:

steveriley [launchpad.net]

We're seeing similar experiences at Kubuntu Forum. In fact, I created a dedicated subforum just for UEFI. I've posted the results of a number of my own experiments, and folks are also discussing theirs. It's been helpful.