AppArmor
From Wikipedia, the free encyclopedia
AppArmor ("Application Armor") is security software for Linux, released under the GNU General Public License. It is currently maintained by Novell. AppArmor allows the system administrator to associate with each program a security profile which restricts the capabilities of that program. It supplements the traditional Unix discretionary access control (DAC) model by providing mandatory access control (MAC).
In addition to manually specifying profiles, AppArmor includes a learning mode, in which violations of the profile are logged, but not prevented. This log can then be turned into a profile, based on the program's typical behavior.
AppArmor is implemented using the Linux Security Modules kernel interface.
AppArmor was created in part as an alternative to SELinux, which critics claim is difficult for administrators to set up and maintain. Unlike SELinux, which is based on applying labels to files, AppArmor works with file paths. Proponents of AppArmor claim that it is less complex and easier for the average user to learn than SELinux. They also claim that AppArmor requires fewer modifications to work with existing systems; for example, SELinux requires a filesystem that supports extended attributes, and thus e.g. cannot provide access control for files mounted via NFS. AppArmor does not mind what kind of file system a file resides on.
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[edit] Criticism
Critics of AppArmor claim that its use of file paths to control access to files is inherently insecure. Under the traditional Unix DAC model, file access is controlled by permissions that are stored in inodes, and multiple file paths may refer to a single inode. AppArmor's critics say that its use of paths unnecessarily departs from this design. For example, if a malicious user is able to create a hard link to a restricted file, the user might gain more permissions to access it; the file could be restricted in different ways depending on the name used to refer to it.
[edit] References
- AppArmor description from openSUSE.org
- LKML thread containing comments and criticism of AppArmor
