Re: [RFC PATCH v2 0/2] ima: Fix detection of read/write violations on stacked filesystems

Amir Goldstein
2024-04-23T06:03:10Z

On Mon, Apr 22, 2024 at 6:07 PM Stefan Berger <stefanb@linux.ibm.com> wrote:
>
> This series fixes the detection of read/write violations on stacked
> filesystems. To be able to access the relevant dentries necessary to
> detect files opened for writing on a stacked filesystem a new d_real_type
> D_REAL_FILEDATA is introduced that allows callers to access all relevant
> files involved in a stacked filesystem while traversing the layers.
>

Stefan,

Both Miklos and myself objected to this solution:
https://lore.kernel.org/linux-unionfs/CAJfpeguctirEYECoigcAsJwpGPCX2NyfMZ8H8GHGW-0UyKfjgg@mail.gmail.com/

Not sure what you are hoping to achieve from re-posting the same solution.

I stopped counting how many times I already argued that *all* IMA/EVM
assertions,
including rw-ro violations should be enforced only on the real inode.
I know this does not work - so you should find out why it does not work and fix
the problem.

Enforcing IMA/EVM on the overlayfs inode layer is just the wrong way IMO.
Not once have I heard an argument from IMA/EVM developers why it is really
needed to enforce IMA/EVM on the overlayfs inode layer and not on the
real inode.
I am sorry that we are failing to communicate on this matter, but I am not
sure how else I can help.

Thanks,
Amir.