DTA

Dottorato

FARA, PIETRO

etd-12302022-231904

Improving safety and security on real-time safety-critical systems

ING-INF/05

Istituto di Tecnologie della Comunicazione, dell'Informazione e della Percezione - PHD IN EMERGING DIGITAL TECHNOLOGIES

Presidente Prof. CUCINOTTA, TOMMASO
Membro Prof.ssa PALUMBO, FRANCESCA
Membro Prof. CRESPO, Alfons
Relatore Prof. BUTTAZZO, GIORGIO CARLO

• real-time
• real-time systems
• safety-critical
• safety
• security
• voting
• response-time analysis

03/07/2023;

completa

In the last decade, the interest in improving safety and security in railway, avionic, aerospace, and automotive fields has increased. Systems designed for such areas are also called safety-critical systems, in which a failure or malfunction can lead to serious risks to human life or severe damage to equipment/property. The main objectives of this work are to improve safety through new methodologies on redundant architectures, improve security using control-flow integrity mechanisms that may indirectly improve safety, and propose a brand new method to exploit real-time features to the programmers in order to make their work easier and less error-prone. <br>When systems have some redundant computational parts, a voting strategy must be applied in order to check if the whole system is working properly. A new scheduling approach for voting routines inspired by the Logical Execution Time (LET) paradigm under 2-out-of-2 redundancy architecture was proposed. Instead of doing the voting part as soon as a task is ready to vote data, the voting phase is delayed at the end of the tasks’ periods and delegated to dedicated tasks. A response-time analysis for real-time tasks and scheduling voting-related activities have been made. Furthermore, an analysis of queuing effects and worst-case transmission delays introduced during inter-replica<br>communications have been proposed.<br>In terms of security, a control-flow integrity methodology called PAC-PL, inspired by the Pointer Authentication Code (PAC) designed by ARM, was proposed. The PAC technology is used to sign and authenticate pointers with a secret key in order to mitigate attacks that may corrupt their content. This technology may also be used to authenticate the return address of a function and improve control-flow integrity. In this work, platforms that don’t implement such security feature but provide programmable logic (also known as FPGA) can improve cyber-security through implementing PAC-PL. In addition, a secure key-management methodology leveraging the virtualization layer is proposed.<br>On the userspace side, a novel real-time POSIX-compliant framework called Real-Time Framework (ReTiF) was designed and developed. The main goal of ReTiF is to provide an API to programmers to improve the usability of existing real-time capabilities exposed by POSIX-compliant operating systems. In particular, the API lets the programmer declare temporal characteristics of real-time tasks (such as period, deadline, computation time, and priority) in a simplified way. The framework then is in charge of choosing the best scheduling policy to satisfy these requirements.

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