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Lennart Poettering, Christian Brauner founded a new company

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Re: Lennart Poettering, Christian Brauner founded a new company

#391

Post by vaylian »

So much negativity in this thread. I actually think this could be useful, because tamper-proof computer systems are useful to prevent evil maid attacks. Especially in the age of Pegasus and other spyware, we should also take physical attack vectors into account.

I can relate to people being rather hostile to the idea of boot verification, because this is a process that is really low level and also something that we as computer experts rarely interact with more deeply. The most challenging part of installing a Linux system is always installing the boot loader, potentially setting up an UEFI partition. These are things that I don't do everyday and that I don't have deep knowledge in. And if things go wrong, then it is extra hard to fix things. Secure boot makes it even harder to understand what is going on. There is a general lack of knowledge of what is happening behind the scenes and it is really hard to learn about it. I feel that the people behind this project should really keep XKCD 2501 in mind when talking to their fellow computer experts.

Re: Lennart Poettering, Christian Brauner founded a new company

#392

Post by Nextgrid »

Gigachad wrote: post #381
Nextgrid wrote: post #98

Earlier quoted context omitted.

Secure Boot only extends the chain of trust from your firmware down the first UEFI binary it loads. Currently SB is effectively useless because it will at best authenticate your kernel but the initrd and subsequent userspace (including programs that run as root) are unverified and can be replaced by malicious alternatives. Secure Boot as it stands right now in the Linux world is effectively an annoyance that’s only t…

Isn’t the idea that the kernel will verify anything beneath it. Secure boot verifies the kernel and then it’s in the hands of the kernel to keep verifying or not.

> the kernel will verify anything beneath it

Yes that's the case - my argument is that Linux currently doesn't have anything standardized to do that.

Your best bet for now is to use a read-only dm-verity-protected volume as the root partition, encode its hash in the initrd, combine kernel + initrd into a UKI and sign that.

I would welcome a standardized approach.

Re: Lennart Poettering, Christian Brauner founded a new company

#393

Post by saghm »

CGMthrowaway wrote: post #340
stogot wrote: post #337

Earlier quoted context omitted.

I’m not sure I understand the threat model for this. Why would I need to worry about my enclave being identifiable? Or is this a business use case? Or why buy used devices if this is a risk?

For most individuals it usually doesn’t matter. It might matter if you have an adversary, e.g. you are a journalist crossing borders, a researcher in a sanctioned country, or an organization trying to avoid cross‑tenant linkage Remote attestation shifts trust from user-controlled software to manufacturer‑controlled hardware identity. It's a gun with a serial number. The Fast and Furious scandal of the Obama years was…

The scandal you cited was that guns controlled by the federal government don't have any obvious reasonable path to being owned by criminals; there isn't an obvious reason for the guns to have left the possession of the government in the first place.

There's not really an equivalent here for a computer owned by an individual because it's totally normal for someone to sell or dispose of a computer, and no one expects someone to be responsible for who else might get their hands on it at that point. If you prove a criminal owns a computer that I owned before, then what? Prosecution for failing to protect my computer from thieves, or for reselling it, or gifting it to a neighbor or family friend? Shifting the trust doesn't matter if what gets exposed isn't actually damaging on any way, and that's what the parent comment is asking about.

The first two examples you give seem to be about an unscrupulous government punishing someone for owning a computer that they consider tainted, but it honestly doesn't seem that believable that a government who would do that would require a burden of proof so high as to require cryptographic attestation to decide on something like that. I don't have a rebuttal for "an organization trying to avoid cross-tenant linkage" though because I'm not sure I even understand what it means: an example would probably be helpful.

Re: Lennart Poettering, Christian Brauner founded a new company

#394

Post by Nextgrid »

blibble wrote: post #224
Nextgrid wrote: post #98

Earlier quoted context omitted.

Secure Boot only extends the chain of trust from your firmware down the first UEFI binary it loads. Currently SB is effectively useless because it will at best authenticate your kernel but the initrd and subsequent userspace (including programs that run as root) are unverified and can be replaced by malicious alternatives. Secure Boot as it stands right now in the Linux world is effectively an annoyance that’s only t…

you can merge the initrd + kernel into one signed binary pretty easily with systemd-boot add luks root, then it's not that bad

Yes, you can. I really don't want to be in the business of building OSes. If these guys make it so that getting reasonable boot security is a simple toggle, I'd be grateful.

Re: Lennart Poettering, Christian Brauner founded a new company

#395

Post by VorpalWay »

gcr wrote: post #271
yxhuvud wrote: post #205

Earlier quoted context omitted.

Afaik bankid will actually run as long as you can install play store (IE the device don't need Google certificate), which isn't great but a little bit better than what it could have been.

That can't be right. My onyx boox note air 2 eInk tablet lets me install the google play store by registering myself as an AOSP developer and enrolling my device's serial number or GSF identifier with Google using some Google Form that some android team somewhere's automated by now. The device has no hardware security features from what I can tell. There's no way this platform would pass muster with any bank.

At least BankId (digital ID thing in Sweden) and some of the Swedish banking apps don't care about if you are rooted on stock Android. I haven't tried custom ROMs in many years, but perhaps it is time for GrapheneOS these days.

Now, if you want to use your phone as a debit/credit card substitute that is different (Google Pay cares, and I don't use it thus).

Anyway, why should banking apps care? It is not like they care when I use the bank from Firefox on my Linux laptop.

Re: Lennart Poettering, Christian Brauner founded a new company

#396

Post by Nextgrid »

okanat wrote: post #267
Nextgrid wrote: post #98

Earlier quoted context omitted.

Secure Boot only extends the chain of trust from your firmware down the first UEFI binary it loads. Currently SB is effectively useless because it will at best authenticate your kernel but the initrd and subsequent userspace (including programs that run as root) are unverified and can be replaced by malicious alternatives. Secure Boot as it stands right now in the Linux world is effectively an annoyance that’s only t…

There is some level of misinformation in your post. Both Windows and Linux check driver signatures. Once you boot Linux in UEFI Secure Boot, you cannot use unsigned drivers because the kernel can detect and activate the lockdown mode. You have to sign all of the drivers within the same PKI of your UEFI key.

> you cannot use unsigned drivers because the kernel can detect and activate the lockdown mode

You don't need to load a driver; you can just replace a binary that's going to be executed as root as part of system boot. This is something a hypothetical code signature verification would detect and prevent.

Failing kernel-level code signature enforcement, the next best step is to have a dm-verity volume as your root partition, with the dm-verity hashes in the initrd within the UKI, and that UKI being signed with secure boot.

This would theoretically allow you to recover from even root-level compromise by just rebooting the machine (assuming the secure boot signing keys weren't on said machine itself).

Re: Lennart Poettering, Christian Brauner founded a new company

#399

Post by Nextgrid »

direwolf20 wrote: post #246
Nextgrid wrote: post #92

Earlier quoted context omitted.

It prevents malware that obtained root access once from forever replacing your kernel/initrd and achieving persistence that way.

Unless that malware is able to activate the secure boot feature on a system where it is not enabled, in which case it permanently prevents me from removing the malware.

Then you reset the firmware and re-enroll your SB keys or disable it completely.

Re: Lennart Poettering, Christian Brauner founded a new company

#400

Post by consumerxyz »

notepad0x90 wrote: post #383
cferry wrote: post #367

Please don't bring attestation to common Linux distributions. This technology, by essence, moves trust to a third party distinct of the user. I don't see how it can be useful in any way to end users like most of us here. Its use by corporations has already caused too much damage and exclusion in the mobile landscape, and I don't want folks like us becoming pariahs in our own world, just because we want machines we bo…

Please do, I disagree with this commenter. You already trust third parties, but there is no reason why that third party can't be the very same entity publishing the distribution. The role corporations play in attestation for the devices you speak of can be displaced by an open source developer, it doesn't need to require a paid certificate, just a trusted one. Furthermore, attestation should be optional at the hardwa…

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