Re: [PATCH v4 2/2] procfs/tasks: add a simple per-task procfs hidepid= field

On Fri, Feb 10, 2017 at 3:44 PM, Kees Cook [off-list ref] wrote:

On Wed, Jan 18, 2017 at 3:35 PM, Andy Lutomirski [off-list ref] wrote:

quoted

On Wed, Jan 18, 2017 at 2:50 PM, Djalal Harouni [off-list ref] wrote:

quoted

Andy I don't follow here, no_new_privs is never cleared right ? I
can't see the corresponding clear bit code for it.

I believe that unsharing userns clears no_new_privs.

Seriously? That's kind of ... weird. I mean, I guess you're
priv-confined in a way, but that seems fragile.

I appear to have made this up.  Either I genuinely pulled it out of
thin air or it was discussed and not done.

$ setpriv --nnp unshare -Ur cat /proc/self/status |grep NoNewPrivs
NoNewPrivs:    1

If it were to be done, it ought to be quite safe except for possible LSM issues.

--Andy