From: Nikita Danilov <nikita@clusterfs.com>
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Date: Wed, 5 Oct 2005 16:17:35 +0400
To: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Cc: Marc Perkel <marc@perkel.com>, linux-kernel@vger.kernel.org
Subject: Re: what's next for the linux kernel?
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Luke Kenneth Casson Leighton writes:

[...]

 > > That's exactly the point: Unix file system model is more flexible than
 > > alternatives. 
 > 
 >  *grin*.  sorry - i have to disagree with you (but see below).
 > 
 >  i was called in to help a friend of mine at EDS to do a bastion sftp
 >  server to write some selinux policy files because POSIX filepermissions
 >  could not fulfil the requirements.

First, I was talking about flexibility attained through the separation
of notions of file and index. You just claimed elsewhere that this is
the direction ntfs took (with the introduction of hard-links).

Then, every security model has its weakness and corner cases. Try to
express

        rw-r-xrw- (0656)

POSIX bits with canonical NT ACLs (hint: in NT allow-ACEs are
accumulated).

[...]

 > 
 >  POSIX permissions were designed to fit into what... 16 bits,
 >  so they didn't have a lot to play with.

That very good property for a security model: simplicity is a virtue
here.

Nikita.
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