RE: [PATCH v2 0/6] bpf-lsm: Extend interoperability with IMA

[Roberto Sassu <roberto.sassu@huawei.com>]

> From: Mimi Zohar [mailto:zohar@linux.ibm.com]
> Sent: Friday, February 25, 2022 1:22 AM
> Hi Roberto,
> 
> On Tue, 2022-02-15 at 13:40 +0100, Roberto Sassu wrote:
> > Extend the interoperability with IMA, to give wider flexibility for the
> > implementation of integrity-focused LSMs based on eBPF.
> 
> I've previously requested adding eBPF module measurements and signature
> verification support in IMA.  There seemed to be some interest, but
> nothing has been posted.

Hi Mimi

for my use case, DIGLIM eBPF, IMA integrity verification is
needed until the binary carrying the eBPF program is executed
as the init process. I've been thinking to use an appended
signature to overcome the limitation of lack of xattrs in the
initial ram disk.

At that point, the LSM is attached and it can enforce an
execution policy, allowing or denying execution and mmap
of files depending on the digest lists (reference values) read
by the user space side.

After the LSM is attached, IMA's job would be just to calculate
the file digests (currently, I'm using an audit policy to ensure
that the digest is available when the eBPF program calls
bpf_ima_inode_hash()).

The main benefit of this patch set is that the audit policy
would not be required and digests are calculated only when
requested by the eBPF program.

Thanks

Roberto

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