U3. Labels & Access Control

U3. Labels & Access Control

1. Information may only flow from an entity with a particular security label to an entity with at least the same label

   • Low level subject may not read up
     • high level subject may not write down
       • Principles of Bell-LaPladula

2. Protection Rings

   • Different subjects & Objects given different numbers (labels)
     • OS enforces control of the layers being accessed
       • OS controls outer layers accessing inner layers
         • All done in a controlled manner
   • Figure shows lowest number as most important

3. VSTa Microkernel

   • Needs work??

4. Bell-LaPladula

   • Based on a confidentiality policy
   • When a subject reads and object, info flows from Object to Subject
   • When writing to an object, info flows from Subject to Object
   • Can write up or on your level, but cant read up
   • Can write on your level and read down, but cant write down

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