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From:   Gabriel Krisman Bertazi <krisman@suse.de>
To:     Matteo Rizzo <matteorizzo@google.com>
Cc:     linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        io-uring@vger.kernel.org, jordyzomer@google.com, evn@google.com,
        poprdi@google.com, corbet@lwn.net, axboe@kernel.dk,
        asml.silence@gmail.com, akpm@linux-foundation.org,
        keescook@chromium.org, rostedt@goodmis.org,
        dave.hansen@linux.intel.com, ribalda@chromium.org,
        chenhuacai@kernel.org, steve@sk2.org, gpiccoli@igalia.com,
        ldufour@linux.ibm.com
Subject: Re: [PATCH 1/1] Add a new sysctl to disable io_uring system-wide
References: <20230627120058.2214509-1-matteorizzo@google.com>
        <20230627120058.2214509-2-matteorizzo@google.com>
Date:   Wed, 28 Jun 2023 09:50:37 -0400
In-Reply-To: <20230627120058.2214509-2-matteorizzo@google.com> (Matteo Rizzo's
        message of "Tue, 27 Jun 2023 12:00:58 +0000")
Message-ID: <87ilb7ofv6.fsf@suse.de>
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Matteo Rizzo <matteorizzo@google.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