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Date: Sat, 2 Nov 2002 21:21:40 -0500 (EST)
From: Alexander Viro <viro@math.psu.edu>
To: Linus Torvalds <torvalds@transmeta.com>
cc: 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:

> The reason I like directory entries as opposed to inodes is that if you
> work this way, you can actually give different people _different_
> capabilities for the same program.  You don't need to have two different
> installs, you can have one install and two different links to it.

	<shrug> that can be done without doing anything to filesystem.
Namely, turn current "nosuid" of vfsmount into a mask of capabilities.
Then use bindings instead of links.  *Note* - binary _is_ marked suid,
mask tells which capabilities _not_ to gain.  It's OK - attempt to
link(2) to the thing using binding will see that oldname and newname
are within different vfsmounts, so instead of link to suid-root binary
you get -EXDEV.

	And that works on any fs, can be made per-user and can be _seen_
by admin - bindings are visible in /proc/mounts (yes, I remember that
we need to fix the crap with pathnames).

	I can do that thing in a weekend - it's trivial to implement.
No need to bugger filesystems for that.

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