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Date:      15 Oct 1997 02:01:07 +0200
From:      joda@pdc.kth.se (Johan Danielsson)
To:        Robert Watson <robert@cyrus.watson.org>
Cc:        Aleph One <aleph1@dfw.net>, freebsd-security@freebsd.org
Subject:   Re: C2 Trusted FreeBSD?
Message-ID:  <xofsou3nbcs.fsf@blubb.pdc.kth.se>
In-Reply-To: Robert Watson's message of Tue, 14 Oct 1997 15:16:19 -0400 (EDT)
References:  <Pine.BSF.3.96.971014150845.1711A-100000@cyrus.watson.org>

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Robert Watson <robert@cyrus.watson.org> writes:

> > HP-UX has had ACLs for quite some time now but not one uses them
> > just because of this.
> 
> This is not entirely true; 

Right, I use ACLs on local file systems, when they are available.

> ls is minorly-modified so as to ignore non-user permissions (AFS, as
> I understand it, does maintain user rwx, etc, just not for others.)

There are no changes to any user level programs in AFS. You need
patched versions of cp/tar/pax/whatever if you want to preserve acls
when copying files. In most situations this isn't a problem.  The
biggest problems are with `smart' programs that think they can figure
out the permissions just by looking at the mode bits.

The mode bits are preserved, but only the owner bits are used, and are
used for everyone (xored with your acl-permissions).

[per file or per directory ACLs]

I actually find the per-directory acls in AFS a feature and not a
bug. The only real problem is with ignorant users that just expects
everything to work the same as in some other filesystem.

The DFS approach to use ACLs on individual files is much more complex.

> The by-directory ACL scheme does not work so well for /dev, for
> example!

File permissions doesn't work well in /dev at all. You really set
permissions on objects, but a device file isn't an object, it's just a
front-end to an object. It would be the same with files if you stored
file permissions in the directories rather than in the inodes.

/Johan



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