Using ambients to control resources

Abstract

Current software and hardware systems, being parallel and reconfigurable, raise new safety and reliability problems, and the resolution of these problems requires new methods. Numerous proposals aim at reducing the threat of bugs and preventing several kinds of attacks. In this paper, we develop an extension of the calculus of mobile ambients, named controlled ambients, that is suited for expressing such issues, specifically denial of service attacks. We present a type system for controlled ambients, which makes static resource control possible in our setting, and enhance it with a rich notion of resources.

When ambients cannot be opened

“…This encoding uses both mobility features from the calculus as well as name restriction. However, several variants of the ambient calculus have been proposed so far [14,2,19] by adding and/or retracting features from the original calculus. In [14], the safe ambient calculus introduces some co-capabilities.…”

“…We prove this fact by defining a general shape matching all reachable processes and by applying an exhaustive inspection of all possibles reductions 2. In[19], the iteration is also defined by means of a reduction rule, but for explicit recursion instead of replication.…”

Space-aware ambients and processes

“…To see the problem, consider again the cab trip example given above. On the one hand, comparing with [31], we notice that we can deal with the cab's space satisfactorily with no need for 3-way synchronisations. On the other hand, however, as already observed in [31], this encoding may lead to unwanted behaviours, since there is no way of preventing a client to enter a cab different from the one called and/or the ambient bye to enter a cab different from the one the client has left.…”

“…As a further example, we give a new version of the cab trip protocol from [31], formulated in our calculus. A customer sends a request for a cab, which then arrives and takes the customer to his destination.…”

Axiomatic Systems for the Bisimilarity on Finite Fair Ambient Processes

“…A piece of resource may move from one ambient to another. Several variants of MA, like Safe Ambients [5], Safe Ambients with Passwords [6], Controlled Ambients [7] and ROAM (The Calculus of Robust Ambients) [8] to name a few, have been proposed to enhance the control power of MA. The Calculus of Fair Ambient [9], or FA, has the most strict rules about when ambients may interact.…”