linux-kernel - Re: [PATCH 3.12 32/64] unix: properly account for FDs passed over unix sockets

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Date:	Thu, 11 Feb 2016 18:32:33 +0100
From:	Willy Tarreau <w@....eu>
To:	Jiri Slaby <jslaby@...e.cz>
Cc:	stable@...r.kernel.org, linux-kernel@...r.kernel.org,
	"David S . Miller" <davem@...emloft.net>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: Re: [PATCH 3.12 32/64] unix: properly account for FDs passed over unix sockets

Hi Jiri,

On Thu, Feb 11, 2016 at 02:59:08PM +0100, Jiri Slaby wrote:
> From: willy tarreau <w@....eu>
> 
> 3.12-stable review patch.  If anyone has any objections, please let me know.
> 
> ===============
> 
> [ Upstream commit 712f4aad406bb1ed67f3f98d04c044191f0ff593 ]
> 
> It is possible for a process to allocate and accumulate far more FDs than
> the process' limit by sending them over a unix socket then closing them
> to keep the process' fd count low.
> 
> This change addresses this problem by keeping track of the number of FDs
> in flight per user and preventing non-privileged processes from having
> more FDs in flight than their configured FD limit.
> 
> Reported-by: socketpair@...il.com
> Reported-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Mitigates: CVE-2013-4312 (Linux 2.0+)
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
> Signed-off-by: Willy Tarreau <w@....eu>
> Signed-off-by: David S. Miller <davem@...emloft.net>
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>

A possible issue was reported regarding this patch, and Hannes
implemented a fix that's not yet in mainline. I guess it's
preferable to postpone this patch for now.

Thanks,
Willy