linux-kernel - Re: strace of io

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Date:   Fri, 24 Jul 2020 09:25:09 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Colin Walters <walters@...bum.org>
Cc:     Andy Lutomirski <luto@...nel.org>, Jens Axboe <axboe@...nel.dk>,
        Christoph Hellwig <hch@....de>,
        Kees Cook <keescook@...omium.org>,
        Pavel Begunkov <asml.silence@...il.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        Matthew Wilcox <willy@...radead.org>,
        Jann Horn <jannh@...gle.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        strace-devel@...ts.strace.io, io-uring@...r.kernel.org,
        Linux API <linux-api@...r.kernel.org>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Stefan Hajnoczi <stefanha@...hat.com>
Subject: Re: strace of io_uring events?

On Thu, Jul 23, 2020 at 09:37:40AM -0400, Colin Walters wrote:
> On Tue, Jul 21, 2020, at 11:58 AM, Stefano Garzarella wrote:
> 
> > my use case concerns virtualization. The idea, that I described in the
> > proposal of io-uring restrictions [1], is to share io_uring CQ and SQ queues
> > with a guest VM for block operations.
> 
> Virtualization being a strong security barrier is in eternal conflict
> with maximizing performance.  All of these "let's add a special
> guest/host channel" are high risk areas.
> 
> And this effort in particular - is it *really* worth it to expose a
> brand new, fast moving Linux kernel interface (that probably hasn't
> been fuzzed as much as it needs to be) to virtual machines?
> 

It is an experiment to explore the potential of io_uring. In addition
the restrictions can also be useful for other use case, for example if
a process  wants to allow another process to use io_uring, but only allowing
a subset of operations.

> People who want maximum performance at the cost of a bit of security
> already have the choice to use Linux containers, where they can use
> io_uring natively.
> 

Thanks,
Stefano