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Introduction to UEFI HTTP(s) Boot with QEMU/OVMF

blog.yadutaf.fr

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Re: Introduction to UEFI HTTP(s) Boot with QEMU/OVMF

#2

Post by nijave »

Having http as an alternative to tftp is a nice win. The range of things that can run an http server is much bigger than tftp

>Additionally, adding the TLS layer brings back the missing integrity and confidentiality guarantees and thus paves the way to move critical boot components out of the trusted network, possibly even to a remote location/Cloud.

Doesn't secure boot already provide this or am I misunderstanding something? I suppose secure boot only provides integrity but not confidentiality although I'm not sure how much confidentiality matters given we're just talking about the kernel here

Re: Introduction to UEFI HTTP(s) Boot with QEMU/OVMF

#5

Post by nijave »

noodlesUK wrote: post #3

To what extent is this possible for actual metal hardware? I'm sure lots of us are running PXE/TFTP systems and HTTP would be a heck of a lot simpler.

There's still the tftp->ipxe->http->??? path. TFTP only needs to serve a 300kb file which can then switch to more robust transport like http for the kernel/OS

You could bypass that by shipping iPXE on USB tho

On metal you also commonly have a BMC so generally that lets you attach an ISO or other storage you can boot from to bypass UEFI primitive PXE. This is probably the biggest one--use BMC functionality instead of UEFI PXE

At home, I use JetKVM or GL.iNet Comet network KVM to bootstrap commodity hardware without BMC (by attaching an ISO). Probably could make a cheap commodity device with Raspberry Pi Zero that does that same thing at lower cost although at that point you're back to "just use USB storage"

Re: Introduction to UEFI HTTP(s) Boot with QEMU/OVMF

#7

Post by LooseMarmoset »

nijave wrote: post #2

Having http as an alternative to tftp is a nice win. The range of things that can run an http server is much bigger than tftp >Additionally, adding the TLS layer brings back the missing integrity and confidentiality guarantees and thus paves the way to move critical boot components out of the trusted network, possibly even to a remote location/Cloud. Doesn't secure boot already provide this or am I misunderstanding s…

Secure boot is designed to verify software signatures. The UEFI bios might support loading software over https, but it isn't part of secure boot. Secure boot would verify any kernels/etc loaded from https.

Re: Introduction to UEFI HTTP(s) Boot with QEMU/OVMF

#9

Post by RulerOf »

LooseMarmoset wrote: post #7
nijave wrote: post #2

Having http as an alternative to tftp is a nice win. The range of things that can run an http server is much bigger than tftp >Additionally, adding the TLS layer brings back the missing integrity and confidentiality guarantees and thus paves the way to move critical boot components out of the trusted network, possibly even to a remote location/Cloud. Doesn't secure boot already provide this or am I misunderstanding s…

Secure boot is designed to verify software signatures. The UEFI bios might support loading software over https, but it isn't part of secure boot. Secure boot would verify any kernels/etc loaded from https.

That was the point as I read it. Payload signature verification is a good and sometimes desirable alternative to transport encryption when the payload itself isn't secret.

Highly-cacheable resources like game and OS updates are often intentionally delivered over http as signed payloads to facilitate middlebox caching.

Re: Introduction to UEFI HTTP(s) Boot with QEMU/OVMF

#10

Post by naturalmovement »

LooseMarmoset wrote: post #7
nijave wrote: post #2

Having http as an alternative to tftp is a nice win. The range of things that can run an http server is much bigger than tftp >Additionally, adding the TLS layer brings back the missing integrity and confidentiality guarantees and thus paves the way to move critical boot components out of the trusted network, possibly even to a remote location/Cloud. Doesn't secure boot already provide this or am I misunderstanding s…

Secure boot is designed to verify software signatures. The UEFI bios might support loading software over https, but it isn't part of secure boot. Secure boot would verify any kernels/etc loaded from https.

> Secure boot is designed to verify software signatures

aka integrity.

HTTPS is a useless gesture here, adding complexity to critical software that needs to be as simple and auditable as possible. Confidentiality is essentially unimportant to anyone but the most autistic of by-the-book nerds. It buys you nothing in a practical sense. Most netbooting happens over closed networks anyway.

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