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From: Willy Tarreau <w@1wt.eu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>,
	David Herrmann <dh.herrmann@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	???????? ?????????????????? <socketpair@gmail.com>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Simon McVittie <simon.mcvittie@collabora.co.uk>
Subject: Re: [PATCH v2] unix: properly account for FDs passed over unix sockets
Date: Tue, 2 Feb 2016 21:58:02 +0100	[thread overview]
Message-ID: <20160202205802.GE25828@1wt.eu> (raw)
In-Reply-To: <CA+55aFykvz0vyWwxve-KHAcZe_hQuE5SDtazD=N_6gLpsU6LHw@mail.gmail.com>

On Tue, Feb 02, 2016 at 12:53:20PM -0800, Linus Torvalds wrote:
> On Tue, Feb 2, 2016 at 12:49 PM, Willy Tarreau <w@1wt.eu> wrote:
> > On Tue, Feb 02, 2016 at 12:44:54PM -0800, Linus Torvalds wrote:
> >>
> >> Umm. I think the "struct cred" may change in between, can't it?
> >
> > You mean for example in case of setuid() or something like this ?
> 
> Yeah. I'd be worried about looking up the creds or user structure
> later, and possibly getting a different one.
> 
> I'd much rather look it up at attach time, and just carry an extra
> pointer around. That seems to be an inherently safer model where
> there's no worry about "what happens if the user does X in the
> meantime".

Normally we can only change from root to non-root, and we don't apply
the limits to root, so if we have the ability to only store one bit
indicating "not tracked" or to simply nullify one pointer to avoid
counting in flight FDs for root, we don't take the risk to recredit
them to the target user after a change.

I just don't know if we can do that though :-/

Willy

  reply	other threads:[~2016-02-02 20:58 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-10  6:54 [PATCH v2] unix: properly account for FDs passed over unix sockets Willy Tarreau
2016-01-10  6:58 ` Willy Tarreau
2016-01-11  5:05 ` David Miller
2016-02-02 17:34 ` David Herrmann
2016-02-02 18:29   ` Hannes Frederic Sowa
2016-02-02 19:29     ` Linus Torvalds
2016-02-02 20:32       ` Hannes Frederic Sowa
2016-02-02 20:39         ` Willy Tarreau
2016-02-02 21:55           ` Hannes Frederic Sowa
     [not found]             ` <CA+55aFzqdR80MKupCs+va8vtbTU67Jobax1QAbfWNktQCXFxpA@mail.gmail.com>
2016-02-03  0:57               ` Hannes Frederic Sowa
2016-02-03  1:12                 ` Hannes Frederic Sowa
2016-02-02 20:44         ` Linus Torvalds
2016-02-02 20:49           ` Willy Tarreau
2016-02-02 20:53             ` Linus Torvalds
2016-02-02 20:58               ` Willy Tarreau [this message]
2016-02-02 20:56           ` Hannes Frederic Sowa
2016-02-03 12:19           ` David Laight
2016-02-03 11:36   ` Simon McVittie
2016-02-03 11:56     ` Hannes Frederic Sowa
2016-02-03 11:56     ` David Herrmann
2016-02-03 12:49       ` Simon McVittie
2016-02-03 14:07       ` Hannes Frederic Sowa
2016-01-10  6:58 Willy Tarreau

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