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Subject: Re: [PATCH v5 0/3] io_uring: add restrictions to support untrusted
 applications and guests
To:     Stefano Garzarella <sgarzare@redhat.com>
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>
References: <20200827134044.82821-1-sgarzare@redhat.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <2ded8df7-6dcb-ee8a-c1fd-e0c420b7b95d@kernel.dk>
Date:   Thu, 27 Aug 2020 07:50:44 -0600
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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.

-- 
Jens Axboe