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

From: Stefano Garzarella <sgarzare@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: Aleksa Sarai <asarai@suse.de>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Jann Horn <jannh@google.com>,
	io-uring@vger.kernel.org,
	Christian Brauner <christian.brauner@ubuntu.com>,
	linux-fsdevel@vger.kernel.org,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	linux-kernel@vger.kernel.org, Sargun Dhillon <sargun@sargun.me>,
	Kees Cook <keescook@chromium.org>, Jeff Moyer <jmoyer@redhat.com>
Subject: Re: [PATCH v5 0/3] io_uring: add restrictions to support untrusted applications and guests
Date: Thu, 27 Aug 2020 16:41:29 +0200	[thread overview]
Message-ID: <20200827144129.5yvu2icj7a5jfp3p@steredhat.lan> (raw)
In-Reply-To: <f7c0ff79-87c0-6c7e-b048-b82a45d0f44a@kernel.dk>

On Thu, Aug 27, 2020 at 08:10:49AM -0600, Jens Axboe wrote:
> On 8/27/20 8:10 AM, Stefano Garzarella wrote:
> > 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! I'll pull in your liburing tests as well once we get the kernel
> side sorted.

Yeah. Let me know if you'd prefer that I send patches on io-uring ML.

About io-uring UAPI, do you think we should set explicitly the enum
values also for IOSQE_*_BIT and IORING_OP_*?

I can send a separated patch for this.

Thanks,
Stefano