Re: [PATCH 0/2] Introduce security_create_user_ns()

[Daniel Borkmann]

On 6/27/22 11:56 PM, Paul Moore wrote:
> On Mon, Jun 27, 2022 at 8:11 AM Christian Brauner <brauner@xxxxxxxxxx> wrote:
> > On Thu, Jun 23, 2022 at 11:21:37PM -0400, Paul Moore wrote:
>
> ...
>
> > > This is one of the reasons why I usually like to see at least one LSM
> > > implementation to go along with every new/modified hook.  The
> > > implementation forces you to think about what information is necessary
> > > to perform a basic access control decision; sometimes it isn't always
> > > obvious until you have to write the access control :)
> >
> > I spoke to Frederick at length during LSS and as I've been given to
> > understand there's a eBPF program that would immediately use this new
> > hook. Now I don't want to get into the whole "Is the eBPF LSM hook
> > infrastructure an LSM" but I think we can let this count as a legitimate
> > first user of this hook/code.
>
> Yes, for the most part I don't really worry about the "is a BPF LSM a
> LSM?" question, it's generally not important for most discussions.
> However, there is an issue unique to the BPF LSMs which I think is
> relevant here: there is no hook implementation code living under
> security/.  While I talked about a hook implementation being helpful
> to verify the hook prototype, it is also helpful in providing an
> in-tree example for other LSMs; unfortunately we don't get that same
> example value when the initial hook implementation is a BPF LSM.

I would argue that such a patch series must come together with a BPF
selftest which then i) contains an in-tree usage example, ii) adds BPF
CI test coverage. Shipping with a BPF selftest at least would be the
usual expectation.

Thanks,
Daniel