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Date: Sat, 2 Nov 2002 23:37:42 -0500 (EST)
From: Alexander Viro <viro@math.psu.edu>
To: Linus Torvalds <torvalds@transmeta.com>
cc: Oliver Xymoron <oxymoron@waste.org>,
       Olaf Dietsche <olaf.dietsche#list.linux-kernel@t-online.de>,
       "Theodore Ts'o" <tytso@mit.edu>, Dax Kelson <dax@gurulabs.com>,
       Rusty Russell <rusty@rustcorp.com.au>, linux-kernel@vger.kernel.org,
       davej@suse.de
Subject: Re: Filesystem Capabilities in 2.6?
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On Sat, 2 Nov 2002, Linus Torvalds wrote:

> However, I think there is a problem with Al's original approach: the bind 
> can _not_ be just a mask that takes away capabilities from a suid 
> application, since that would imply that the app has to be marked suid in 
> the first place (and accessing it _without_ going through the bind will 
> give it elevated privileges, which is what we're trying to avoid).

No, that's OK -

mount --bind /usr/bin/foo.real /usr/bin/foo.real
mount -o remount,nosuid /usr/bin/foo.real

or equivalent couple of mount(2) calls will do the trick nicely (and that,
BTW, we have right now - you can selectively disable/enable suid on files
and entire subtrees).

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