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Novell releases AppArmorNovell releases AppArmorPosted Jan 16, 2006 11:53 UTC (Mon) by nix (subscriber, #2304)In reply to: Novell releases AppArmor by etbe Parent article: Novell releases AppArmor
Well, as I understand it AppArmor uses the filename to *look up* the inode number and then tags the inode. Obviously no other system would be secure under hardlinks, especially if as standard POSIX semantics demand any user can hardlink files owned by other users into directories they control. (I think it reasonable to assume that any system designed by Crispin Cowan wouldn't have a design flaw as large as you imply in it!)
Obviously the AppArmor globbing/regexing thing is something which should be used with care: don't put wildcards at the front of the name!
What might really cause problems for AppArmor, and for any filename-based system, is wide use of filesystem namespaces. If /etc/shadow refers to a different file depending on the PID, what do you do?
(Mind you, this screws up conventional Unix security as well. I think that no matter what you do to the filesystem namespace, / and /etc had better remain non-writable by anyone but root.)
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Novell releases AppArmor Posted Jan 17, 2006 2:43 UTC (Tue) by etbe (subscriber, #17516) [Link] With SE Linux there are access controls to determine which processes cancreate a hard link to a file. For example with the strict policy most processes on the system are not permitted to create hard links to files in /etc. I believe that some of the Common Criteria certifications require that the system label Inodes not file names so any system that doesn't do something similar to what SE Linux does will not do well in certification. In a conventional Unix system there is nothing preventing you from having a /etc/shadow file in a chroot environment with different permissions to the "real" one. A bigger problem for AppArmor is the fact that file specs are relative to the root of a file system. So /etc/shadow is equivalent to /home/etc/shadow if /home is a separate file system.
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