linux-kernel - Re: [PATCH] vfs: new O

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Message-Id: <200910141514.52811.agruen@suse.de>
Date:	Wed, 14 Oct 2009 15:14:52 +0200
From:	Andreas Gruenbacher <agruen@...e.de>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	Andreas Dilger <adilger@....com>, Valdis.Kletnieks@...edu,
	linux@...blig.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vfs: new O_NODE open flag

On Monday 28 September 2009 18:04:10 Miklos Szeredi wrote:
> The point of the above example was that reopening a file descriptor
> with upgraded (or downgraded) access mode is even now possible.  Which
> either means:
> 
>  a) the current permission model under /proc/PID/fd has a security
>     hole (which Jamie is worried about)

No worries -- access to /proc/PID/fd/* requires ptrace access to PID, so we do 
not have a security hole here. The ptrace checks were introduced here:

	778c1144771f0064b6f51bee865cceb0d996f2f9
	df26c40e567356caeefe2861311e19c54444d917

Cheers,
Andreas
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