linux-kernel - Re: [PATCH v2 2/2] net: socket: implement SO

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Message-ID: <CAGbU3_m_2_6iq-ZCMJ0i7E=4nFi6o=akd9_QpeRSa26=U67yog@mail.gmail.com>
Date:   Sun, 23 Aug 2020 15:28:23 -0700
From:   Pascal Bouchareine <kalou@....net>
To:     David Miller <davem@...emloft.net>
Cc:     linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        netdev@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v2 2/2] net: socket: implement SO_DESCRIPTION

On Sat, Aug 22, 2020 at 2:01 PM David Miller <davem@...emloft.net> wrote:
> > About the pid part -
> > On top of multiple pids to scan for a given socket, there's also the
> > security provided by /proc - I'm not sure what inet_diag does for that
> > So maybe users calling it will need to scan /proc for a long time anyway...
> >
> > Or is that doable?
>
> I'd like to kindly ask that you do more research into how this kind of
> information is advertised to the user using modern interfaces, and what
> kinds of permissions and checks are done for those.

If we wanted to get rid of having to scan /proc from userland when
using sock_diag to identify associated processes,
I suppose scanning for pids would be the most annoying part?

I understand sock_diag uses CAP_NET_ADMIN for some sensitive bits.

I thought it would require an additional bit of logic to let an
unprivileged user access its own socket "sensitive" data.

Your message makes me think I need to read a lot more about it, so
I'll try that - but more importantly
as you mention APIs and modern interfaces, I think eBPF is going to be
of great help to try and hack
around this data without disturbing existing APIs.

Thanks for taking the time to look into it