Re: [9fans] How to implement a moral equivalent of automounter in Plan9?

[Roman Shaposhnik <rvs@sun.com>]

On Dec 2, 2008, at 5:36 PM, Dan Cross wrote:
> On Tue, Dec 2, 2008 at 7:07 PM, erik quanstrom
> <quanstro@quanstro.net> wrote:
>> currently one can prevent external changes to a
>> namespace by creating a unique ns with rfork.
>> if /proc/$pid/ns were writable, one would not not
>> be possible without yet another mechanism.
>
> chmod?  I guess it comes back to, "How do you define external."  If
> you mean another process owned by the same user, then it breaks down
> (hello trojan horse).
>
> There are many things that would be *possible* with /proc, some of
> them ill advised.  For instance, why can't I 'mkdir /proc/n/' and have
> it create a new process?

There's an aswer to that given by Ken in the Plan 9 paper:
       http://www.cs.bell-labs.com/sys/doc/9.html:
-----------------------------------------------------------------------------------------------------
Nonetheless, it is possible to push the idea of file-based computing
too far.
Converting every resource in the system into a file system is a kind
of metaphor,
and metaphors can be abused. A good example of restraint is/proc,
which is
only a view of a process, not a representation. To run processes, the
usual
fork and exec calls are still necessary, rather than doing something
like
      cp /bin/date /proc/clone/mem
------------------------------------------------------------------------------------------------------

Thanks,
Roman.

P.S. I suppose one might argue that it is also an answer to *my*
original
question -- /proc/<id>/ns is just a representation.