[PATCH] userns,pidns: Verify the userns for new pid namespaces

[Eric W. Biederman]

ebiederm at xmission.com (Eric W. Biederman) writes:

> "Serge E. Hallyn" <serge at hallyn.com> writes:
>
>> Quoting Eric W. Biederman (ebiederm at xmission.com):
>>> 
>>> It is pointless and confusing to allow a pid namespace hierarchy and
>>> the user namespace hierarchy to get out of sync.  The owner of a child
>>> pid namespace should be the owner of the parent pid namespace or
>>> a descendant of the owner of the parent pid namespace.
>>> 
>>> Otherwise it is possible to construct scenarios where it is legal to
>>> do something in a parent pid namespace but in a child pid namespace.
>>
>> Hi,
>>
>> did you mean 'but not in a child...' above?
>
> Actually I believe I meant:
>
>>> Otherwise it is possible to construct scenarios where it is not legal
>>> to do something in a parent pid namespace but it is legal a child pid
>>> namespace.
>
> I definitely need to fix that wording thank you.

Looking at some more I mean:

Otherwise it is possible to construct scenarios where a process has a
capability in a over a parent pid namespace but does not have the
capability over a child pid namespace.  Which confusingly makes
permission checks non-transitive.


Eric