linux-kernel - Re: [PATCH v4 3/3] io_uring: allow disabling rings during the creation

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Message-ID: <202008270803.6FD7F63@keescook>
Date:   Thu, 27 Aug 2020 08:04:15 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Stefano Garzarella <sgarzare@...hat.com>
Cc:     Jens Axboe <axboe@...nel.dk>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Jann Horn <jannh@...gle.com>, Jeff Moyer <jmoyer@...hat.com>,
        linux-fsdevel@...r.kernel.org, Sargun Dhillon <sargun@...gun.me>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        linux-kernel@...r.kernel.org, Aleksa Sarai <asarai@...e.de>,
        io-uring@...r.kernel.org
Subject: Re: [PATCH v4 3/3] io_uring: allow disabling rings during the
 creation

On Thu, Aug 27, 2020 at 09:18:02AM +0200, Stefano Garzarella wrote:
> On Wed, Aug 26, 2020 at 12:50:31PM -0700, Kees Cook wrote:
> > On Thu, Aug 13, 2020 at 05:32:54PM +0200, Stefano Garzarella wrote:
> > > This patch adds a new IORING_SETUP_R_DISABLED flag to start the
> > > rings disabled, allowing the user to register restrictions,
> > > buffers, files, before to start processing SQEs.
> > > 
> > > When IORING_SETUP_R_DISABLED is set, SQE are not processed and
> > > SQPOLL kthread is not started.
> > > 
> > > The restrictions registration are allowed only when the rings
> > > are disable to prevent concurrency issue while processing SQEs.
> > > 
> > > The rings can be enabled using IORING_REGISTER_ENABLE_RINGS
> > > opcode with io_uring_register(2).
> > > 
> > > Suggested-by: Jens Axboe <axboe@...nel.dk>
> > > Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
> > 
> > Reviewed-by: Kees Cook <keescook@...omium.org>
> > 
> > Where can I find the io_uring selftests? I'd expect an additional set of
> > patches to implement the selftests for this new feature.
> 
> Since the io_uring selftests are stored in the liburing repository, I created
> a new test case (test/register-restrictions.c) in my fork and I'll send it
> when this series is accepted. It's available in this repository:
> 
> https://github.com/stefano-garzarella/liburing (branch: io_uring_restrictions)

Ah-ha; thank you! Looks good. :)

-- 
Kees Cook