Re: [PATCH v4 1/2] tiocsti-restrict : Add owner user namespace to tty_struct

From: Matt Brown
Date: Wed May 03 2017 - 16:04:01 EST

On 05/03/2017 03:45 PM, Greg KH wrote:
On Wed, May 03, 2017 at 12:32:07PM -0700, Kees Cook wrote:
On Mon, Apr 24, 2017 at 6:57 AM, Serge E. Hallyn <serge@xxxxxxxxxx> wrote:
Quoting Matt Brown (matt@xxxxxxxxx):
This patch adds struct user_namespace *owner_user_ns to the tty_struct.
Then it is set to current_user_ns() in the alloc_tty_struct function.

This is done to facilitate capability checks against the original user
namespace that allocated the tty.

E.g. ns_capable(tty->owner_user_ns,CAP_SYS_ADMIN)

This combined with the use of user namespace's will allow hardening
protections to be built to mitigate container escapes that utilize TTY
ioctls such as TIOCSTI.


Signed-off-by: Matt Brown <matt@xxxxxxxxx>

Acked-by: Serge Hallyn <serge@xxxxxxxxxx>

This Ack didn't end up in the v5, but I think it stands, yes?

Greg, is the v5 okay to pull for you or would a v6 with Acks/Reviews
included be preferred?

v6 would be great, and we are dropping patch 2 from the series, right?
I was expecting this to be resent. I'll start looking at new patches
like this after 4.12-rc1 is out.

I will create a v6 with the Acks/Reviews. I'd like to keep patch 2 in
since that got acked by at least Serge. (Kees also? or just patch 1?)


greg k-h