Re: [PATCH 0/5] vm: boot sub-VMs from dm-verity roots and enable IPE

[Alyssa Ross <hi@alyssa.is>]

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colby@colbyt.com writes:

> Yes this is me laying the groundwork for/ trying to solve 
>
> "Look into Integrity Policy Enhancement LSM
> Apparently this enforces that executables must be authenticated by dm-verity. Could we use this?"
>
> I may have forgotten to push all the files but I got it implemented and working --- only I did not want to push actual IPE policies in a patch, as that has a substantial possibility to break things.

Ah, yes.  I meant IPE on the host when I wrote that.  I'll update the
text to make that clearer.  I don't immediately see any value in IPE in
VMs.

> On Friday, June 26th, 2026 at 8:15 AM, Alyssa Ross <hi@alyssa.is> wrote:
>
>> colbyt <colby@colbyt.com> writes:
>> 
>> > This series changes the app VM and net VM root images to boot through
>> > dm-verity, then enables IPE kernel support for the sub-VMs and the
>> > Spectrum host rootfs.
>> >
>> > Each sub-VM disk now has a verity metadata partition and an EROFS root
>> > partition.  The build installs the root hash next to the disk image, and
>> > the VM boot paths pass that hash to a shared initramfs.  The initramfs
>> > uses the hash to find both partitions, opens /dev/mapper/root-verity, and
>> > switches into it read-only.
>> >
>> > The last two patches only enable kernel support for IPE.  They do not
>> > install an IPE policy.  With the existing generated kernel config,
>> > enabling SECURITY_IPE also enables the dm-verity root-hash provider, so
>> > later policy work can match files from verified roots.
>> 
>> Would you mind explaining your motivation / the direction you envisage
>> here in a bit more detail?  Given that the VM gets its root file system
>> and the corresponding verity hash from the same place (the host file
>> system), there's no immediate security benefit from using dm-verity,
>> right?  Is the idea rather to enable some sort of cool IPE thing for
>> which dm-verity is a requirement, but that's not implemented yet as part
>> of this series?
>> 
>> (I really appreciate the quality of your patches BTW — you've obviously
>> gone to some effort to identify and follow all the tiny little
>> conventions we have in the codebase.  Thank you!)
>> 

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