kernel-hardening - Re: [PATCH v5 0/3] io_uring: add restrictions to support untrusted applications and guests

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Date: Thu, 27 Aug 2020 16:10:02 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Jens Axboe <axboe@...nel.dk>
Cc: Aleksa Sarai <asarai@...e.de>,
	Kernel Hardening <kernel-hardening@...ts.openwall.com>,
	Jann Horn <jannh@...gle.com>, io-uring@...r.kernel.org,
	Christian Brauner <christian.brauner@...ntu.com>,
	linux-fsdevel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Stefan Hajnoczi <stefanha@...hat.com>, linux-kernel@...r.kernel.org,
	Sargun Dhillon <sargun@...gun.me>,
	Kees Cook <keescook@...omium.org>, Jeff Moyer <jmoyer@...hat.com>
Subject: Re: [PATCH v5 0/3] io_uring: add restrictions to support untrusted
 applications and guests

On Thu, Aug 27, 2020 at 07:50:44AM -0600, Jens Axboe wrote:
> On 8/27/20 7:40 AM, Stefano Garzarella wrote:
> > v5:
> >  - explicitly assigned enum values [Kees]
> >  - replaced kmalloc/copy_from_user with memdup_user [kernel test robot]
> >  - added Kees' R-b tags
> > 
> > v4: https://lore.kernel.org/io-uring/20200813153254.93731-1-sgarzare@redhat.com/
> > v3: https://lore.kernel.org/io-uring/20200728160101.48554-1-sgarzare@redhat.com/
> > RFC v2: https://lore.kernel.org/io-uring/20200716124833.93667-1-sgarzare@redhat.com
> > RFC v1: https://lore.kernel.org/io-uring/20200710141945.129329-1-sgarzare@redhat.com
> > 
> > Following the proposal that I send about restrictions [1], I wrote this series
> > to add restrictions in io_uring.
> > 
> > I also wrote helpers in liburing and a test case (test/register-restrictions.c)
> > available in this repository:
> > https://github.com/stefano-garzarella/liburing (branch: io_uring_restrictions)
> > 
> > Just to recap the proposal, the idea is to add some restrictions to the
> > operations (sqe opcode and flags, register opcode) to safely allow untrusted
> > applications or guests to use io_uring queues.
> > 
> > The first patch changes io_uring_register(2) opcodes into an enumeration to
> > keep track of the last opcode available.
> > 
> > The second patch adds IOURING_REGISTER_RESTRICTIONS opcode and the code to
> > handle restrictions.
> > 
> > The third patch adds IORING_SETUP_R_DISABLED flag to start the rings disabled,
> > allowing the user to register restrictions, buffers, files, before to start
> > processing SQEs.
> > 
> > Comments and suggestions are very welcome.
> 
> Looks good to me, just a few very minor comments in patch 2. If you
> could fix those up, let's get this queued for 5.10.
> 

Sure, I'll fix the issues. This is great :-)

Thanks,
Stefano

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