FDP_ACF.1 Security attribute based access control
User application notes
This component provides requirements for a mechanism that mediates access control based on security attributes associated with subjects and objects. Each object and subject has a set of associated attributes, such as location, time of creation, access rights (e.g., Access Control Lists (ACLs)). This component allows the PP/ST author to specify the attributes that will be used for the access control mediation. This component allows access control rules, using these attributes, to be specified.
Examples of the attributes that a PP/ST author might assign are presented in the following paragraphs.
An identity attribute may be associated with users, subjects, or objects to be used for mediation. Examples of such attributes might be the name of the program image used in the creation of the subject, or a security attribute assigned to the program image.
A time attribute can be used to specify that access will be authorised during certain times of the day, during certain days of the week, or during a certain calendar year.
A location attribute could specify whether the location is the location of the request for the operation, the location where the operation will be carried out, or both. It could be based upon internal tables to translate the logical interfaces of the TSF into locations such as through terminal locations, CPU locations, etc.
A grouping attribute allows a single group of users to be associated with an operation for the purposes of access control. If required, the refinement operation should be used to specify the maximum number of definable groups, the maximum membership of a group, and the maximum number of groups to which a user can concurrently be associated.
This component also provides requirements for the access control security functions to be able to explicitly authorise or deny access to an object based upon security attributes. This could be used to provide privilege, access rights, or access authorisations within the TOE. Such privileges, rights, or authorisations could apply to users, subjects (representing users or applications), and objects.
Operations
Assignment:
In FDP_ACF.1.1, the PP/ST author should specify an access control SFP name that the TSF is to enforce. The name of the access control SFP, and the scope of control for that policy are defined in components from FDP_ACC.
In FDP_ACF.1.1, the PP/ST author should specify the security attributes and/or named groups of security attributes that the function will use in the specification of the rules. For example, such attributes may be things such as the user identity, subject identity, role, time of day, location, ACLs, or any other attribute specified by the PP/ST author. Named groups of security attributes can be specified to provide a convenient means to refer to multiple security attributes. Named groups could provide a useful way to associate "roles" defined in FMT_SMR Security management roles, and all of their relevant attributes, with subjects. In other words, each role could relate to a named group of attributes.
In FDP_ACF.1.2, the PP/ST author should specify the SFP rules governing access among controlled subjects and controlled objects using controlled operations on controlled objects. These rules specify when access is granted or denied. It can specify general access control functions (e.g. typical permission bits) or granular access control functions (e.g. ACLs).
In FDP_ACF.1.3, the PP/ST author should specify the rules, based on security attributes, that explicitly authorise access of subjects to objects that will be used to explicitly authorise access. These rules are in addition to those specified in FDP_ACF.1.1. They are included in FDP_ACF.1.3 as they are intended to contain exceptions to the rules in FDP_ACF.1.1. An example of rules to explicitly authorise access is based on a privilege vector associated with a subject that always grants access to objects covered by the access control SFP that has been specified. If such a capability is not desired, then the PP/ST author should specify "none".
In FDP_ACF.1.4, the PP/ST author should specify the rules, based on security attributes, that explicitly deny access of subjects to objects. These rules are in addition to those specified in FDP_ACF.1.1. They are included in FDP_ACF.1.4 as they are intended to contain exceptions to the rules in FDP_ACF.1.1. An example of rules to explicitly deny access is based on a privilege vector associated with a subject that always denies access to objects covered by the access control SFP that has been specified. If such a capability is not desired, then the PP/ST author should specify "none".