Comprehensive Specification and Efficient Enforcement of Role-based Access Control Policies using a Model-driven Approach

Doctoral thesis (2017)

Prohibiting unauthorized access to critical resources and data has become a major requirement for enterprises. Access control (AC) mechanisms manage requests from users to access system resources; the ... [more ▼]

Prohibiting unauthorized access to critical resources and data has become a major requirement for enterprises. Access control (AC) mechanisms manage requests from users to access system resources; the access is granted or denied based on the authorization policies defined within the enterprise. One of the most used AC paradigms is role-based access control (RBAC), in which access rights are determined based on the user’s role. In this dissertation, we focus on the problems of modeling, specifying and enforcing complex RBAC policies, by making the following contributions: 1. the GemRBAC+CTX conceptual model, a UML extension of the RBAC model that includes all the entities required to express the various types of RBAC policies found in the literature, with a specific emphasis on contextual policies. For each type of policy, we provided the corresponding formalization using the Object Constraint Language (OCL) to operationalize the access decision for a user’s request using model-driven technologies. 2. the GemRBAC-DSL language, a domain-specific language for RBAC policies designed on top of the GemRBAC+CTX model. The language is characterized by a syntax close to natural language, which does not require any mathematical background for expressing RBAC policies. The language supports all the authorization policies captured by the GemRBAC+CTX model. 3. MORRO, a model-driven framework for the run-time enforcement of RBAC policies expressed in GemRBAC-DSL, built on top of the GemRBAC+CTX model. MORRO provides policy enforcement for both access and usage control. 4. three tools (an editor for GemRBAC-DSL, a model transformation tool for GemRBAC-DSL, a run-time enforcement framework) have been implemented and released as part of this work. The GemRBAC+CTX model and the GemRBAC-DSL language have been adopted by our industrial partner for the specification of the access control policies of a Web application in the domain of disaster reliefintervention. We have extensively evaluated the applicability and the scalability of MORRO on this Web application. The experimental results show that an access decision can be made on average, in less than 107 ms and that the time for processing a notification of an AC-related event is less than 512ms. Furthermore, both the access decision time and the execution time for processing a notification of an AC-related event scale—in the majority of the cases—linearly with respect to the parameters characterizing AC configurations; in the remaining cases, the access decision time is constant. [less ▲]

GemRBAC-DSL: a High-level Specification Language for Role-based Access Control Policies

Report (2016)

A role-based access control (RBAC) policy restricts a user to perform operations based on her role within an organization. Several RBAC models have been proposed to represent different types of RBAC ... [more ▼]

A role-based access control (RBAC) policy restricts a user to perform operations based on her role within an organization. Several RBAC models have been proposed to represent different types of RBAC policies. However, the expressiveness of these models has not been matched by specification languages for RBAC policies. Indeed, existing policy specification languages do not support all the types of RBAC policies defined in the literature. In this paper we aim to bridge the gap between highly-expressive RBAC models and policy specification languages, by presenting GemRBAC-DSL, a new specification language designed on top of an existing, generalized conceptual model for RBAC. The language sports a syntax close to natural language, to encourage its adoption among practitioners. We also define semantic checks to detect conflicts and inconsistencies among the policies written in a GemRBAC-DSL specification. We show how the semantics of GemRBAC-DSL can be expressed in terms of an existing formalization of RBAC policies as OCL (Object Constraint Language) constraints on the corresponding RBAC conceptual model. This formalization paves the way to define a model-driven approach for the enforcement of policies written in GemRBAC-DSL. [less ▲]

A Comprehensive Modeling Framework for Role-based Access Control Policies

in Journal of Systems and Software (2015), 107(September,2015), 110-126

Prohibiting unauthorized access to critical resources and data has become a major requirement for enter- prises; access control (AC) mechanisms manage requests from users to access system resources. One ... [more ▼]

Prohibiting unauthorized access to critical resources and data has become a major requirement for enter- prises; access control (AC) mechanisms manage requests from users to access system resources. One of the most used AC paradigms is role-based access control (RBAC), in which access rights are determined based on the user’s role. Many different types of RBAC policies have been proposed in the literature, each one accompanied by the corresponding extension of the original RBAC model. However, there is no unified framework that can be used to define all these types of policies in a coherent way, using a common model. In this paper we propose a model-driven engineering approach, based on UML and the Object Constraint Language (OCL), to enable the precise specification and verification of such policies. More specifically, we first present a taxonomy of the various types of RBAC policies proposed in the literature. We also propose the GemRBAC model, a generalized model for RBAC that includes all the entities required to define the classified policies. This model is a conceptual model that can also serve as data model to operationalize data collection and verification. Lastly, we formalize the classified policies as OCL constraints on the GemRBAC model. [less ▲]