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

[colby@colbyt.com]

So instinctively the path I took there was to do IPE on apple end to end from host to VM in an accountability chain, but not sure of the validity of my taste there -- I just like treating internal assumptions as hostile instead of trusted -- I was hoping to achieve an inter-vm attestation system which would use things like this, but tbh did not think deeply.



On Thursday, July 2nd, 2026 at 7:22 AM, Alyssa Ross <hi@alyssa.is> wrote:

> 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!)
> >> 
>