Mobile Wireless Device with Protected File System
A mobile wireless device programmed with a file system which is partitioned into multiple root directories. The partitioning of the file system ‘cages’ processes as it prevents them from seeing any files they should not have access to. A Trusted Computing Base verifies whether or not a process has the required privileges or capabilities to access root sub-trees. The particular directory a file is placed into automatically determines its accessibility to different processes—i.e. a process can only access files in certain root directories.
1 . A single-user mobile wireless device programmed with a file system which is partitioned into multiple root directories; in which the location of a file in a particular one of the root directories fully determines which processes running on the device can access the file and hence obviates the need for any access control list.
2 . The device of claim 1 in which access rights of the file are modified by moving its location in the file system.
3 . The device of claim 1 in which one of the root directories is reserved for components forming a Trusted Computing Base.
4 . The device of claim 1 in which one or more trusted components verify whether or not a process has the required privileges or capabilities to access a file system sub-tree.
5 . The device of claim 1 in which a process is restricted to accessing only its own private area of the file system.
6 . The device of claim 5 in which the private area is accessible only to a process with a correct secure identifier.
7 . The device of claim 1 in which the root directories are each functionally equivalent to the following:
(a) a root directory with sub-trees accessible to any process that has been granted operating system privileges over all files;
(b) a root directory with sub-trees accessible only to a process with a correct secure identifier;
(c) a root directory with sub-trees that are public read-only;
(d) a root directory with sub-trees that are available to any process for file read and write operations, file creation and deletion.