On Tue, 3 Jul 2001, Crispin Cowan wrote: > I'd like to better understand this suggestion. Various modules (DTE, > SubDomain) really do need the absolute path of the file being accessed. If > there is not a hook that provides that information, then there needs to be a > way to reconstruct the info. I'm assuming that "Doug's suggestion" is such a > means? You don't need the absolute pathname at the time of the lookup or file creation operation. Suppose that you represent your pathname-based configuration as a tree. When a file system is mounted, you can set a field in the security object of the root directory inode to point into your tree at the appropriate point for the absolute pathname of the mount point (easily accessible at that point). [You need an equivalent to the old add_vfsmnt hook for this purpose or at least a post_mount hook.] On subsequent lookups, you can set the field in the security objects for directories and files in that file system by starting from the location in the tree referenced by the parent directory inode's security object and looking up the component name in your tree. Doug suggested an inode-based approach like SELinux for assigning types to existing files, but noted that you could use this kind of approach (similar to the approach used by the NAI Labs' DTE prototype) to provide the ability to assign types to files that don't exist yet. In that case, the tree would only contain leaf nodes for files that don't exist. But you could use the same approach for all files (as in the NAI Labs' DTE prototype). Keep in mind that at a high-level, SELinux uses pathnames as well. But these are mapped down to inodes during initialization, thereby avoiding the well-known problems with changes to the namespace and object aliasing. Using inodes at runtime seems preferable to us - you want to protect data contained in an object, not a pathname. -- Stephen D. Smalley, NAI Labs ssmalleyat_private _______________________________________________ linux-security-module mailing list linux-security-moduleat_private http://mail.wirex.com/mailman/listinfo/linux-security-module
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