Lecture 2: Security Policy Models

Fred ChongCS290N Architectural Support for

Secure and Reliable Computing

Multi-Level vs Multi-Lateral Policies

Bell-La Padua Policy

BLP vs BIBA

Biba

Example: BLP password file protection

• Password file is “high”• Network reads and writes are “low”• Malware from the network is “low,” can’t read

password file (read of “high” from “low”)• Even if Malware becomes “high” somehow,

can’t write password data to the network (write of “high” to “low”)

Example: Biba protects system files

• System files are “high”• Malware from the network is “low”• Malware can’t write to system files (“low”

writes to “high”)• Hardware dynamic information flow tracking

techniques (taint tracking) implement Biba

Chinese Wall

BLP vs Chinese Wall

Clark-Wilson

BLP vs Clark-Wilson

BLP with Codewords

• “Need to know”• A Lattice Model

BMA medical record policy