# CEN429 — Week 2 — Bell–LaPadula (confidentiality) sample policy
# Military classification analogy: a higher level = more secret.
# Rule: "no read up, no write down".

MODEL   BLP

LEVEL   Public     0
LEVEL   Secret     1
LEVEL   TopSecret  2

# Subjects (users) and their clearance levels
SUBJECT clerk    Public
SUBJECT officer  Secret
SUBJECT general  TopSecret

# Objects (documents) and their classification levels
OBJECT  notice     Public
OBJECT  plan       Secret
OBJECT  operation  TopSecret

# DAC matrix: let's say the owner has given everyone generous permission (so
# we can see what BLP does on its own). In reality DAC and MAC are applied
# together.
RIGHT   clerk    notice     rw
RIGHT   clerk    plan       rw
RIGHT   clerk    operation  rw
RIGHT   officer  notice     rw
RIGHT   officer  plan       rw
RIGHT   officer  operation  rw
RIGHT   general  notice     rw
RIGHT   general  plan       rw
RIGHT   general  operation  rw

# --- Requests ---
# clerk reads/writes something at their own level: no problem
REQUEST clerk    read   notice
REQUEST clerk    write  notice
# clerk wants to read a more secret document: BLP says "no read up"
REQUEST clerk    read   operation
# general reads the top-secret document: their own level, no problem
REQUEST general  read   operation
# general writes top-secret information into a public document (a leak!):
# BLP's "no write down" blocks this
REQUEST general  write  notice
# clerk may write to a more secret document (writing up is allowed under BLP)
REQUEST clerk    write  operation
