linux-security-module November 2007 archive
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linux-security-module: Object Capabilities for AppArmor

Object Capabilities for AppArmor

From: Crispin Cowan <crispin_at_nospam>
Date: Sat Nov 17 2007 - 19:18:04 GMT
To: apparmor-dev <>, "General discussions concerning capability systems." <>, LSM ML <>

>From various discussions in these mailing lists, I have recently moved
from on-the-fence to inclined in favor of adding some Object Capabilities to the AppArmor system. However, because of the UNIX legacy, and the way that AppArmor is intended to work, it cannot be a pure OC system, it will have to be some kind of a hybrid. I particularly like the file descriptor OC hybrid that Rob Meijer has proposed, but will need some refinement.

For example, in UNIX file descriptors are left open on exec(), unless you do something to close them. Sometimes software deliberately leaves file descriptors open as a parameter passing technique, but there is also a chronic sequence of security vulnerabilities where FDs are unintentionally left open. Thus AppArmor needs some kind of policy mechanism to specify whether FDs should be left open on exec() in particular circumstances.

To figure out just how to do this, I propose a discussion on the apparmor-dev mailing list (where the reply-to: is pointed) and a virtual conference in the #apparmor IRC room. American Thanks Giving holiday is coming, so I propose approximately a week's discussion, and a virtual conference in #apparmor on Sunday November 25th. The exact date & time of the virtual conference can be determined in follow-ups to this post on apparmor-dev.

Please join this discussion if you are interested. apparmor-dev holds non-member posts for moderation by a human. The human policy is to filter spam only, but if you want your posts to go straight through unmoderated, please subscribe to apparmor-dev, it is not a high volume list. Well, it wasn't until just now :)


    Crispin -- Crispin Cowan, Ph.D. CEO, Mercenary Linux Itanium. Vista. GPLv3. Complexity at work - To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to More majordomo info at