Date: Tue, 25 Apr 2017 15:55:21 +0100 From: Alan Cox <gnomes@...rguk.ukuu.org.uk> To: Matt Brown <matt@...tt.com> Cc: serge@...lyn.com, jmorris@...ei.org, gregkh@...uxfoundation.org, jslaby@...e.com, corbet@....net, keescook@...omium.org, akpm@...ux-foundation.org, jannh@...gle.com, kernel-hardening@...ts.openwall.com, linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org Subject: Re: [PATCH v4 1/2] tiocsti-restrict : Add owner user namespace to tty_struct On Mon, 24 Apr 2017 01:15:11 -0400 Matt Brown <matt@...tt.com> wrote: > 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. Regardles of the TIOCSTI usefulness this makes complete sense. Alan
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