Efficient memory access is critical for computing systems, yet the CPU's management of data transfers can create bottlenecks. To counter this, most advanced high-throughput systems utilize Direct Memory Access (DMA) controllers, where peripherals (such as network interfaces and USB devices) can access memory independently of the CPU, improving transfer speeds. However, this bypass also introduces security vulnerabilities if the DMA controller is not configured correctly, as DMA devices may be used to overwrite critical data or leak information. This thesis proposes a method to represent complex DMA driver source code as an abstract mathematical model in the formal analysis tool HOL4 (where users can define models and prove properties about them with HOL4 and checking the correctness of the proofs). This model enables the formal verification of the DMA driver source code's critical properties like memory isolation, initial configurations, and many more. Additionally, the thesis introduces a methodology to convert the verified HOL4 models into executable C source code, thus obtaining a formally verified C source code. The synthesized code is evaluated against the original driver source code by emulating the DMA operation in software and using fuzzing techniques for any compile and runtime errors. This validates the approach, demonstrating that converting a C driver source code into a HOL4 model and then back into C source code after verification yields a formally verified C source code. This thesis applies this methodology to DMA controllers for four devices namely Intel 8237a, Intel IXGBE x550 Ethernet Controller, MPC 5200 SoC, and STM32 DMAC. / Master of Science / This thesis addresses the critical issue of ensuring secure memory access in computing systems, focusing on Direct Memory Access (DMA) controllers. DMA devices can bypass the CPU to access a range of memory directly, enhancing transfer speeds but introducing security vulnerabilities like overwriting or leaking critical data if not configured correctly. This thesis proposes a method to model complex DMA driver source codes such that they can be rigorously analyzed with computer assistance. This approach is significant as it provides a structured methodology for analyzing DMA driver source code, reducing the risk of errors and vulnerabilities. The thesis also proposes a method to convert the abstract representation into executable source code, thus improving the reliability and security of DMA operations in computing systems.

Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2003. / Includes bibliographical references (leaves 20-21). / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Linux has become a viable alternative to Windows in recent years. This investigation looks at the feasibility of porting the software for a PC-based medical device to Linux. Using an open-source operating system frees developers from the constraints imposed by relying on a single company for the development platform. Several porting methods are considered. The port method chosen allows development on the Windows version to continue while simultaneously testing on Linux, without creating separate versions of the software. Differences in the way the software interacts with the operating system and with the hardware have to be addressed. A Linux environment was created in which to run the software and determine how to reconcile these differences. No major hurdles to using Linux exist, so it appears to be a viable platform on which to conduct future development. / by Steven B. Lustbader. / M.Eng.and S.B.

Thesis (M.S.)--Mississippi State University. Department of Computer Science and Engineering. / Title from title screen. Includes bibliographical references.

Includes index. / Also issued online.

Thesis (M. Sc. (Computer Science))--Rhodes University, 2004.

abstract: This research describes software based remote attestation schemes for obtaining the integrity of an executing user application and the Operating System (OS) text section of an untrusted client platform. A trusted external entity issues a challenge to the client platform. The challenge is executable code which the client must execute, and the code generates results which are sent to the external entity. These results provide the external entity an assurance as to whether the client application and the OS are in pristine condition. This work also presents a technique where it can be verified that the application which was attested, did not get replaced by a different application after completion of the attestation. The implementation of these three techniques was achieved entirely in software and is backward compatible with legacy machines on the Intel x86 architecture. This research also presents two approaches to incorporating software based "root of trust" using Virtual Machine Monitors (VMMs). The first approach determines the integrity of an executing Guest OS from the Host OS using Linux Kernel-based Virtual Machine (KVM) and qemu emulation software. The second approach implements a small VMM called MIvmm that can be utilized as a trusted codebase to build security applications such as those implemented in this research. MIvmm was conceptualized and implemented without using any existing codebase; its minimal size allows it to be trustworthy. Both the VMM approaches leverage processor support for virtualization in the Intel x86 architecture. / Dissertation/Thesis / Ph.D. Computer Science 2011

Modern computer systems require efficient data transfers involving memory in order to get the best possible performance. However, even the most optimized CPUs take too long to access memory regions, which takes time away from doing the typical computations that a CPU is designed to do. To solve this, Direct Memory Access (DMA) is used, which allows peripherals and other hardware accelerators, such as stand-alone DMA Controllers (DMACs), to read and write memory without CPU intervention. However, DMA introduces security problems in which attackers are able to leak data and overwrite critical system components by bypassing typical operating system security mechanisms. This thesis presents a case study to model as well as verify DMA device driver code in HOL4, which is an interactive theorem prover (ITP) used for machine-checked verification. This thesis verifies parts of Intel's IXGBE X550 device driver, which is a complex, 10 Gbit Network Interface Card (NIC). This verification takes the first significant step towards proving that the DMA device driver configures the DMA device such that it preserves memory isolation, which ensures that only memory that is intended to be readable and writable will be accessed. This thesis also provides a formal method to verify that a loop terminates under all possible cases. This can be used to further verify the correctness of a DMA driver. These contributions allow for the overall increased security of memory when using DMA device drivers that are verified by this approach, leading to the hindrance of attacks on systems utilizing DMA. / Master of Science / Modern computer systems use Direct Memory Accesses (DMAs) in order to offload the CPU from doing memory transfers. However, this poses the problem that the CPU is not able to monitor every memory access made through DMA. This can lead to attackers utilizing vulnerabilities in the device drivers used to perform DMA operations. This thesis addresses this problem by modeling and verifying properties of a device driver that will prove that the driver configures DMA such that it is isolated. This thesis also models and verifies a loop to ensure that it terminates, further verifying the correctness of a function in a device driver. These contributions are significant because they allow for increased security of a computer system's memory, reducing the likelihood of attacks.

Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (MScEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The Linux operating system and shared Ethernet are alternative technologies with the potential to reduce both the development time and costs of satellites as well as the supporting infrastructure. Modular satellites, ground stations and rapid proto typing testbeds also have a common requirement for distributed real-time computation. The identified technologies were investigated to determine whether this requirement could also be met. Various real-time extensions and modifications are currently available for the Linux operating system. A suitable open source real-time extension called Real-Time Application Interface (RTAI) was selected for the implementation of an experimental distributed real-time system. Experimental results showed that the RTAI operating system could deliver deterministic realtime performance, but only in the absence of non-real-time load. Shared Ethernet is currently the most popular and widely used commercial networking technology. However, Ethernet wasn't developed to provide real-time performance. Several methods have been proposed in literature to modify Ethernet for real-time communications. A token passing protocol was found to be an effective and least intrusive solution. The Real-Time Token (RTToken) protocol was designed to guarantee predictable network access to communicating real-time tasks. The protocol passes a token between nodes in a predetermined order and nodes are assigned fixed token holding times. Experimental results proved that the protocol offered predictable network access with bounded jitter. An experimental distributed real-time system was implemented, which included the extension of the RTAI operating system with the RTToken protocol, as a loadable kernel module. Real-time tasks communicated using connectionless Internet protocols. The Real-Time networking (RTnet) subsystem of RTAI supported these protocols. Under collision-free conditions consistent transmission delays with bounded jitter was measured. The integrated RTToken protocol provided guaranteed and bounded network access to communicating real-time tasks, with limit overheads. Tests exhibited errors in some of the RTAI functionality. Overall the investigated technologies showed promise in being able to meet the distributed real-time requirements of various applications, including those found in the satellite environment. / AFRIKAANSE OPSOMMING: Die Linux bedryfstelsel en gedeelde Ethernet is geïdentifiseer as potensiële tegnologieë vir satelliet bedryf wat besparings in koste en vinniger ontwikkeling te weeg kan bring. Modulêr ontwerpte satelliete, grondstasies en ontwikkeling platforms het 'n gemeenskaplike behoefte vir verspreide intydse verwerking. Verskillende tegnologieë is ondersoek om te bepaal of aan die vereiste ook voldoen kan word. Verskeie intydse uitbreidings en modifikasies is huidiglik beskikbaar vir die Linux bedryfstelsel. Die "Real-Time Application Interface" (RTAI) bedryfstelsel is geïdentifiseer as 'n geskikte intydse uitbreiding vir die implementering van 'n eksperimentele verspreide intydse stelsel. Eksperimentele resultate het getoon dat die RTAI bedryfstelsel deterministies en intyds kan opereer, maar dan moet dit geskied in die afwesigheid van 'n nie-intydse verwerkingslas. Gedeelde Ethernet is 'n kommersiële network tegnologie wat tans algemeen beskikbaar is. Die tegnologie is egter nie ontwerp vir intydse uitvoering nie. Verskeie metodes is in die literatuur voorgestelom Ethernet te modifiseer vir intydse kommunikasie. Hierdie ondersoek het getoon dat 'n teken-aangee protokol die mees effektiewe oplossing is en waarvan die implementering min inbreuk maak. Die "Real-Time Token" (RTToken) protokol is ontwerp om voorspelbare netwerk toegang tot kommunikerende intydse take te verseker. Die protokol stuur 'n teken tussen nodusse in 'n voorafbepaalde volgorde. Nodusse word ook vaste teken hou-tye geallokeer. Eksperimentele resultate het aangedui dat die protokol deterministiese netwerk toegang kan verseker met begrensde variasies. 'n Eksperimentele verspreide intydse stelsel is geïmplementeer. Dit het ingesluit die uitbreiding van die RTAI bedryfstelsel met die RTToken protokol; verpak as 'n laaibare bedryfstelsel module. Intydse take kan kommunikeer met verbindinglose protokolle wat deur die "Real-Time networking" (RTnet) substelsel van RTAI ondersteun word. Onder ideale toestande is konstante transmissie vertragings met begrensde variasies gemeet. Die integrasie van die RTToken protokol het botsinglose netwerk toegang aan kommunikerende take verseker, met beperkte oorhoofse koste as teenprestasie. Eksperimente het enkele foute in die funksionaliteit van RTAI uitgewys. In die algemeen het die voorgestelde tegnologieë getoon dat dit potensiaal het vir verskeie verspreide intydse toepassings in toekomstige satelliet en ook ander omgewings.

New hardware devices are continually being released to the public by hardware manufactures around the world. For these new devices to be usable under a PC operating system, device drivers that extend the functionality of the target operating system have to be constructed. This work examines and compares the device driver architectures currently in use by two of the most widely used operating systems, Microsoft’s Windows and Linux. The IEEE1394 (high speed serial bus) device driver stacks on each operating system are examined and compared as an example of a major device driver stack implementation, including driver requirements for the upcoming IEEE1394.1 bridging standard.