linux-kernel - Re: [PATCH] net: tls: fix possible race condition between do_tls_getsockopt_conf() and do_tls_setsockopt

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Date:   Fri, 24 Feb 2023 13:06:25 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Sabrina Dubroca <sd@...asysnail.net>
Cc:     Hangyu Hua <hbh25y@...il.com>, Florian Westphal <fw@...len.de>,
        borisp@...dia.com, john.fastabend@...il.com, davem@...emloft.net,
        edumazet@...gle.com, pabeni@...hat.com, davejwatson@...com,
        aviadye@...lanox.com, ilyal@...lanox.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: tls: fix possible race condition between
 do_tls_getsockopt_conf() and do_tls_setsockopt_conf()

On Fri, 24 Feb 2023 21:22:43 +0100 Sabrina Dubroca wrote:
> > Right, the bug and the fix seem completely bogus.
> > Please make sure the bugs are real and the fixes you sent actually 
> > fix them.  
> 
> I suggested a change of locking in do_tls_getsockopt_conf this
> morning [1]. The issue reported last seemed valid, but this patch is not
> at all what I had in mind.
> [1] https://lore.kernel.org/all/Y/ht6gQL+u6fj3dG@hog/

Ack, I read the messages out of order, sorry.

> do_tls_setsockopt_conf fills crypto_info immediately from what
> userspace gives us (and clears it on exit in case of failure), which
> getsockopt could see since it's not locking the socket when it checks
> TLS_CRYPTO_INFO_READY. So getsockopt would progress up to the point it
> finally locks the socket, but if setsockopt failed, we could have
> cleared TLS_CRYPTO_INFO_READY and freed iv/rec_seq.

Makes sense. We should just take the socket lock around all of
do_tls_getsockopt(), then?