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

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Date:   Wed, 28 Jun 2023 09:50:37 -0400
From:   Gabriel Krisman Bertazi <krisman@...e.de>
To:     Matteo Rizzo <matteorizzo@...gle.com>
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        io-uring@...r.kernel.org, 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

Matteo Rizzo <matteorizzo@...gle.com> writes:

> diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
> index d85d90f5d000..3c53a238332a 100644
> --- a/Documentation/admin-guide/sysctl/kernel.rst
> +++ b/Documentation/admin-guide/sysctl/kernel.rst
> @@ -450,6 +450,20 @@ this allows system administrators to override the
>  ``IA64_THREAD_UAC_NOPRINT`` ``prctl`` and avoid logs being flooded.
>  
>  
> +io_uring_disabled
> +=========================
> +
> +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 had an internal request for something like this recently.  If we go
this route, we could use a intermediary option that limits io_uring
to root processes only.

-- 
Gabriel Krisman Bertazi