Secure Virtualization and Multicore Platforms State-of-the-Art report

SVaM

Secure Virtualization of Latency-Constrained Systems

Virtualization is a mature technology in server and desktop environments where multiple systems are consolidate onto a single physical hardware platform, increasing the utilization of todays multi-core systems as well as saving resources such as energy, space and costs compared to multiple single systems. Looking at embedded environments reveals that many systems use multiple separate computing systems inside, including requirements for real-time and isolation properties. For example, modern high-comfort cars use up to a hundred embedded computing systems. Consolidating such diverse configurations promises to save resources such as energy and weight. In my work I propose a secure software architecture that allows consolidating multiple embedded software systems with timing constraints. The base of the architecture builds a microkernel-based operating system that supports a variety of different virtualization approaches through a generic interface, supporting hardware-assisted virtualization and paravirtualization as well as multiple architectures. Studying guest systems with latency constraints with regards to virtualization showed that standard techniques such as high-frequency time-slicing are not a viable approach. Generally, guest systems are a combination of best-effort and real-time work and thus form a mixed-criticality system. Further analysis showed that such systems need to export relevant internal scheduling information to the hypervisor to support multiple guests with latency constraints. I propose a mechanism to export those relevant events that is secure, flexible, has good performance and is easy to use. The thesis concludes with an evaluation covering the virtualization approach on the ARM and x86 architectures and two guest operating systems, Linux and FreeRTOS, as well as evaluating the export mechanism

Operating System Kernels on Multi-core Architectures

Operating System (OS) kernels have been under research and development for decades, mainly assuming single processor and distributed hardware systems. With the recent rise of multi-core chips that may incorporate a network on chip (NoC), new challenges have appeared that were not considered before. Given that a complete multi-core system that works on a single system on chip (SoC) is now the normal case, different cores on a single SoC may share other physical resources and data. This new sharing scheme on a SoC affects crucial aspects of an overall system like correctness, performance, predictability, scalability and security. Both hardware and OSs to flexibly cooperate in order to provide solutions for such challenges. SoC mimics the internet somehow now, with different cores acting as computer nodes, and the network medium is given in an advanced digital fabrics like buses or NoCs, that are a current research area. However, OSs are still assuming some (hardware) features like single physical memory and memory sharing for inter-process communication, page-based protection, cache operations, even when evolving from uniprocessor to multi-core processors. Such features not only may degrade performance and other system aspects, but also some of them make no sense for a multi-core SoC, and introduce some barriers and limitations. While new OS research is considering different kernel designs to cope up with multi-core systems, they are still limited by the current commercial hardware architectures. The objective of this thesis is to assess different kernel designs and implementations on multi-core hardware architectures. Part of the contributions of the thesis is porting RTEMS (RTOS) and seL4 microkernel to Epiphany and RISC-V hardware architectures respectively, trading-off the design and implementation decisions. This hands-on experience gave a better understanding of the real-world challenges regarding kernel designs and implementations

Maruchi OS kankyo o shiensuru sofutowea oyobi hadowea kino no teian

制度:新 ; 報告番号:甲3534号 ; 学位の種類:博士(工学) ; 授与年月日:2012/2/25 ; 早大学位記番号:新587

Thin Hypervisor-Based Security Architectures for Embedded Platforms

Virtualization has grown increasingly popular, thanks to its benefits of isolation, management, and utilization, supported by hardware advances. It is also receiving attention for its potential to support security, through hypervisor-based services and advanced protections supplied to guests. Today, virtualization is even making inroads in the embedded space, and embedded systems, with their security needs, have already started to benefit from virtualization’s security potential. In this thesis, we investigate the possibilities for thin hypervisor-based security on embedded platforms. In addition to significant background study, we present implementation of a low-footprint, thin hypervisor capable of providing security protections to a single FreeRTOS guest kernel on ARM. Backed by performance test results, our hypervisor provides security to a formerly unsecured kernel with minimal performance overhead, and represents a first step in a greater research effort into the security advantages and possibilities of embedded thin hypervisors. Our results show that thin hypervisors are both possible and beneficial even on limited embedded systems, and sets the stage for more advanced investigations, implementations, and security applications in the future

System Support for Distributed Energy Management in Modular Operating Systems

This thesis proposes a novel approach for managing energy in modular operating systems. Our approach enables energy awareness if the resource-management subsystem is distributed among multiple operating-system modules. There are four key achievements: a model for modularization-aware energy management; the support for exposed and distributed energy accounting and allocation; the use of different energy-management interaction protocols; and, finally, the support virtualization of energy effects

Master of Science

thesisOperating system (OS) kernel extensions, particularly device drivers, are one of the primary sources of vulnerabilities in commodity OS kernels. Vulnerabilities in driver code are often exploited by attackers, leading to attacks like privilege escalation, denial-of-service, and arbitrary code execution. Today, kernel extensions are fully trusted and operate within the core kernel without any form of isolation. But history suggests that this trust is often misplaced, emphasizing a need for some isolation in the kernel. We develop a new framework for isolating device drivers in the Linux kernel. Our work builds on three fundamental principles: (1) strong isolation of the driver code; (2) reuse of existing driver while making no or minimal changes to the source; and (3) achieving same or better performance compared to the nonisolated driver. In comparison to existing driver isolation schemes like driver virtual machines and user-level device driver implementations, our work strives to avoid modifying existing code and implements an I/O path without incurring substantial performance overhead. We demonstrate our approach by isolating a unmodified driver for a null block device in the Linux kernel, achieving near-native throughput for block sizes ranging from 512B to 256KB and outperforming the nonisolated driver for block sizes of 1MB and higher

Advancing Operating Systems via Aspect-Oriented Programming

Operating system kernels are among the most complex pieces of software in existence to- day. Maintaining the kernel code and developing new functionality is increasingly compli- cated, since the amount of required features has risen significantly, leading to side ef fects that can be introduced inadvertedly by changing a piece of code that belongs to a completely dif ferent context. Software developers try to modularize their code base into separate functional units. Some of the functionality or “concerns” required in a kernel, however, does not fit into the given modularization structure; this code may then be spread over the code base and its implementation tangled with code implementing dif ferent concerns. These so-called “crosscutting concerns” are especially dif ficult to handle since a change in a crosscutting concern implies that all relevant locations spread throughout the code base have to be modified. Aspect-Oriented Software Development (AOSD) is an approach to handle crosscutting concerns by factoring them out into separate modules. The “advice” code contained in these modules is woven into the original code base according to a pointcut description, a set of interaction points (joinpoints) with the code base. To be used in operating systems, AOSD requires tool support for the prevalent procedu- ral programming style as well as support for weaving aspects. Many interactions in kernel code are dynamic, so in order to implement non-static behavior and improve performance, a dynamic weaver that deploys and undeploys aspects at system runtime is required. This thesis presents an extension of the “C” programming language to support AOSD. Based on this, two dynamic weaving toolkits – TOSKANA and TOSKANA-VM – are presented to permit dynamic aspect weaving in the monolithic NetBSD kernel as well as in a virtual- machine and microkernel-based Linux kernel running on top of L4. Based on TOSKANA, applications for this dynamic aspect technology are discussed and evaluated. The thesis closes with a view on an aspect-oriented kernel structure that maintains coherency and handles crosscutting concerns using dynamic aspects while enhancing de- velopment methods through the use of domain-specific programming languages