Re: [PATCH] capabilites, take 2

From: Stephen Smalley
Date: Fri May 14 2004 - 10:23:53 EST


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).

--
Stephen Smalley <sds@xxxxxxxxxxxxxx>
National Security Agency

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