Re: [PATCH v3 0/4] Introduce security_create_user_ns()

Frederick Lawler
2022-08-01T13:14:02Z

On 7/22/22 7:20 AM, Paul Moore wrote:
> On July 22, 2022 2:12:03 AM Martin KaFai Lau <kafai@fb.com> wrote:
>
>> On Thu, Jul 21, 2022 at 12:28:04PM -0500, Frederick Lawler wrote:
>>> While creating a LSM BPF MAC policy to block user namespace creation, we
>>> used the LSM cred_prepare hook because that is the closest hook to prevent
>>> a call to create_user_ns().
>>>
>>> The calls look something like this:
>>>
>>> cred = prepare_creds()
>>> security_prepare_creds()
>>> call_int_hook(cred_prepare, ...
>>> if (cred)
>>> create_user_ns(cred)
>>>
>>> We noticed that error codes were not propagated from this hook and
>>> introduced a patch [1] to propagate those errors.
>>>
>>> The discussion notes that security_prepare_creds()
>>> is not appropriate for MAC policies, and instead the hook is
>>> meant for LSM authors to prepare credentials for mutation. [2]
>>>
>>> Ultimately, we concluded that a better course of action is to introduce
>>> a new security hook for LSM authors. [3]
>>>
>>> This patch set first introduces a new security_create_user_ns() function
>>> and userns_create LSM hook, then marks the hook as sleepable in BPF.
>> Patch 1 and 4 still need review from the lsm/security side.
>
>
> This patchset is in my review queue and assuming everything checks out, I expect to merge it after the upcoming merge window closes.
>
> I would also need an ACK from the BPF LSM folks, but they're CC'd on this patchset.
>

Based on last weeks comments, should I go ahead and put up v4 for
5.20-rc1 when that drops, or do I need to wait for more feedback?

> --
> paul-moore.com
>
>