Demands, Solutions, and Improvements for Linux Filesystem Security

Securing file resources under Linux is a team effort. No one library, application, or kernel feature can stand alone in providing robust se-curity. Current Linux access control mecha-nisms work in concert to provide a certain level of security, but they depend upon the integrity of the machine itself to protect that data. Once the data leaves that machine, or if the machine itself is physically compromised, those access control mechanisms can no longer protect the data in the filesystem. At that point, data pri-vacy must be enforced via encryption. As Linux makes inroads in the desktop market, the need for transparent and effective data en-cryption increases. To be practically deploy-able, the encryption/decryption process must be secure, unobtrusive, consistent, flexible, re-liable, and efficient. Most encryption mecha-nisms that run under Linux today fail in one or more of these categories. In this paper, we discuss solutions to many of these issues via the integration of encryption into the Linux filesystem. This will provide access control en-forcement on data that is not necessarily un-der the control of the operating environment. We also explore how stackable filesystems, Ex-tended Attributes, PAM, GnuPG web-of-trust, supporting libraries, and applications (such as GNOME/KDE) can all be orchestrated to pro-vide robust encryption-based access control over filesystem content