linux-kernel - Re: [PATCH 1/1] Add a new sysctl to disable io

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Message-ID: <e8924389-985a-42ad-9daf-eca2bf12fa57@acm.org>
Date:   Tue, 27 Jun 2023 10:10:36 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Matteo Rizzo <matteorizzo@...gle.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, io-uring@...r.kernel.org
Cc:     jordyzomer@...gle.com, evn@...gle.com, poprdi@...gle.com,
        corbet@....net, axboe@...nel.dk, asml.silence@...il.com,
        akpm@...ux-foundation.org, keescook@...omium.org,
        rostedt@...dmis.org, dave.hansen@...ux.intel.com,
        ribalda@...omium.org, chenhuacai@...nel.org, steve@....org,
        gpiccoli@...lia.com, ldufour@...ux.ibm.com
Subject: Re: [PATCH 1/1] Add a new sysctl to disable io_uring system-wide

On 6/27/23 05:00, Matteo Rizzo wrote:
> +Prevents all processes from creating new io_uring instances. Enabling this
> +shrinks the kernel's attack surface.
> +
> += =============================================================
> +0 All processes can create io_uring instances as normal. This is the default
> +  setting.
> +1 io_uring is disabled. io_uring_setup always fails with -EPERM. Existing
> +  io_uring instances can still be used.
> += =============================================================

I'm using fio + io_uring all the time on Android devices. I think we need a
better solution than disabling io_uring system-wide, e.g. a mechanism based
on SELinux that disables io_uring for apps and that keeps io_uring enabled
for processes started via 'adb root && adb shell ...'

Bart.