Re: [PATCH] capabilites, take 2

From: Andy Lutomirski
Date: Fri May 14 2004 - 10:58:55 EST




Stephen Smalley wrote:

On Fri, 2004-05-14 at 08:03, Albert Cahalan wrote:

This would be an excellent time to reconsider how capabilities
are assigned to bits. You're breaking things anyway; you might
as well do all the breaking at once. I want local-use bits so
that the print queue management access isn't by magic UID/GID.
We haven't escaped UID-as-priv if server apps and setuid apps
are still making UID-based access control decisions.


Capabilities are a broken model for privilege management; try RBAC/TE
instead. http://www.securecomputing.com/pdf/secureos.pdf has notes
about the history and comparison of capabilities vs. TE.

Instead of adding new capability bits, replace capable() calls with LSM
hook calls that offer you finer granularity both in operation and in
object-based decisions, and then use a security module like SELinux to
map that to actual permission checks. SELinux provides a framework for
defining security classes and permissions, including both definitions
used by the kernel and definitions used by userspace policy enforcers
(ala security-enhanced X).


Thanks -- turning brain back on, SELinux is obviously better than any
fine-grained capability scheme I can imagine.

So unless anyone convinces me you're wrong, I'll stick with just
fixing up capabilities to work without making them finer-grained.

--Andy
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