[RFC][PATCH 4/4] PID: use the target ID specified in procfs

[Eric W. Biederman]

Oren Laadan <orenl at cs.columbia.edu> writes:

>>> I'm sorry but I'm pretty new in this domain, so I don't see what are the
>>> namespaces where setting (or pre-setting) the id would be a problem?
>>
>> pids to some extent as people use them in all kinds of files.  Being
>> able to force the pid of another process could make a hard to trigger
>> security hole with file permissions absolutely trivial to hit.
>
> Since the intent of this mechanism is to allow ckpt/restart, it makes
> sense to only allow this operation during restart. For example, in zap,
> containers have a state, e.g. running, stopped, ckpt, restart, and this
> is only possible in restart state; Furthermore, a container can only be
> put in restart state at creation time, and only by root. Of course, you
> should only trust that as much as you trust the root  :O

Yes and thanks.

The notion of the state of a container makes a lot of sense (even if
we never implement explicit state bits).

Eric