netdev - Re: [PATCH v2 net] net/tls: fix encryption error checking

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Message-ID: <20200519161018.0f9be0d7@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Tue, 19 May 2020 16:10:18 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Vadim Fedorenko <vfedorenko@...ek.ru>
Cc:     Boris Pismenny <borisp@...lanox.com>,
        Aviad Yehezkel <aviadye@...lanox.com>,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH v2 net] net/tls: fix encryption error checking

On Wed, 20 May 2020 01:49:33 +0300 Vadim Fedorenko wrote:
> On 20.05.2020 01:04, Jakub Kicinski wrote:
> > On Tue, 19 May 2020 13:20:43 +0300 Vadim Fedorenko wrote:  
> >> bpf_exec_tx_verdict() can return negative value for copied
> >> variable. In that case this value will be pushed back to caller
> >> and the real error code will be lost. Fix it using signed type and
> >> checking for positive value.
> >>
> >> Fixes: d10523d0b3d7 ("net/tls: free the record on encryption error")
> >> Fixes: d3b18ad31f93 ("tls: add bpf support to sk_msg handling")
> >> Signed-off-by: Vadim Fedorenko <vfedorenko@...ek.ru>  
> > If the error encountered is transient we will still drop some data from
> > the stream, because the record that was freed may have included data
> > from a previous send call. Still, cleaning up the error code seems like
> > an improvement.
> >
> > John, do you have an opinion on this?  
> 
> Jakub, maybe it is better to free only in case of fatal encryption error? I mean
> when sk->sk_err is EBADMSG. Because in case of ENOMEM we will iterate to
> alloc_payload and in case of ENOSPC we will return good return code and send
> open_rec again on next call. The EBADMSG state is the only fatal state that needs
> freeing of allocated record.

Sounds good!