168 research outputs found
Music as Dialogic Sounding Device in the Novels of Thomas Pynchon
Combining key aspects of literary, musical, and cultural theory, my thesis investigates the significance of music in the work of the contemporary American novelist Thomas Pynchon. His novels, along with a handful of short stories, are so saturated with musical references and fictional songs that it borders on eccentricity. It is my argument that understanding musical presence and the way it is represented here is of crucial importance to our understanding one of the overarching themes of Pynchon’s writing: that of communication, and specifically the persistence of communication from the margins of society in the face of restricting and divisive political forces. My aim is to establish a positive view of Pynchon’s representation of music as a site of social intercourse, in the literal sense – a shared territory between language and artistic expression, through which both listener and performer are placed in a socially communicative framework; but also metaphorically, as a model for dialogic interaction that can undercut official discourse. As with all things in Pynchon, hope is tempered with a degree of cynicism: his depiction of musical media, for example, is varied and complex, and can be seen as a commentary on issues such as authenticity, the commodification of art, and corporate co-optation of subcultural expression. Nonetheless, the ubiquity of music in Pynchon is such that the attempt to communicate is persistently foregrounded.
Chapter one establishes the techniques by which Pynchon incorporates the subject of music into his writing, before setting the significance of the author’s enterprise against the light of critical debates concerning the social efficacy and political energy of musical expression. The subsequent four chapters offer an in-depth look at Pynchon’s engagement with music in the light of themes that feed into the broader, overarching compulsion signalled above
Is communications a strategic activity in UK Education?
This qualitative exploratory paper investigates whether communications/public relations is regarded by opinion formers in UK education as a strategic business activity or a tactical marketing tool. It is based upon depth interviews with 16 senior managers with strategic roles in UK higher or further education, or Government bodies, conducted between June and September 2004. The findings seem to suggest that communications/PR is ideally seen by leaders as a strategic function, but that there are limitations to this vision becoming a reality. The research goes on to offer initial conclusions on some of the issues surrounding perception, resource, and implementation of strategic communications/PR in UK education, with implications for practitioners considered
The Meaning of Memory Safety
We give a rigorous characterization of what it means for a programming
language to be memory safe, capturing the intuition that memory safety supports
local reasoning about state. We formalize this principle in two ways. First, we
show how a small memory-safe language validates a noninterference property: a
program can neither affect nor be affected by unreachable parts of the state.
Second, we extend separation logic, a proof system for heap-manipulating
programs, with a memory-safe variant of its frame rule. The new rule is
stronger because it applies even when parts of the program are buggy or
malicious, but also weaker because it demands a stricter form of separation
between parts of the program state. We also consider a number of pragmatically
motivated variations on memory safety and the reasoning principles they
support. As an application of our characterization, we evaluate the security of
a previously proposed dynamic monitor for memory safety of heap-allocated data.Comment: POST'18 final versio
Into the depths of C: Elaborating the de facto standards
C remains central to our computing infrastructure. It is notionally defined by ISO standards, but in reality the properties of C assumed by systems code and those implemented by compilers have diverged, both from the ISO standards and from each other, and none of these are clearly understood. We make two contributions to help improve this error-prone situation. First, we describe an in-depth analysis of the design space for the semantics of pointers and memory in C as it is used in practice. We articulate many specific questions, build a suite of semantic test cases, gather experimental data from multiple implementations, and survey what C experts believe about the de facto standards. We identify questions where there is a consensus (either following ISO or differing) and where there are conflicts. We apply all this to an experimental C implemented above capability hardware. Second, we describe a formal model, Cerberus, for large parts of C. Cerberus is parameterised on its memory model; it is linkable either with a candidate de facto memory object model, under construction, or with an operational C11 concurrency model; it is defined by elaboration to a much simpler Core language for accessibility, and it is executable as a test oracle on small examples. This should provide a solid basis for discussion of what mainstream C is now: what programmers and analysis tools can assume and what compilers aim to implement. Ultimately we hope it will be a step towards clear, consistent, and accepted semantics for the various use-cases of C.We acknowledge funding from EPSRC grants EP/H005633 (Leadership Fellowship, Sewell) and EP/K008528 (REMS Programme Grant), and a Gates Cambridge Scholarship (Nienhuis). This work is also part of the CTSRD projects sponsored by the Defense Advanced Research Projects Agency (DARPA) and the Air Force Research Laboratory (AFRL), under contract FA8750-10-C-0237.This is the author accepted manuscript. The final version is available from the Association for Computing Machinery via http://dx.doi.org/10.1145/2908080.290808
CHERI: A hybrid capability-system architecture for scalable software compartmentalization
CHERI extends a conventional RISC Instruction-
Set Architecture, compiler, and operating system to support
fine-grained, capability-based memory protection to mitigate
memory-related vulnerabilities in C-language TCBs. We describe
how CHERI capabilities can also underpin a hardware-software
object-capability model for application compartmentalization
that can mitigate broader classes of attack. Prototyped as an
extension to the open-source 64-bit BERI RISC FPGA softcore
processor, FreeBSD operating system, and LLVM compiler,
we demonstrate multiple orders-of-magnitude improvement in
scalability, simplified programmability, and resulting tangible
security benefits as compared to compartmentalization based on
pure Memory-Management Unit (MMU) designs. We evaluate
incrementally deployable CHERI-based compartmentalization
using several real-world UNIX libraries and applications.We thank our colleagues Ross Anderson, Ruslan Bukin,
Gregory Chadwick, Steve Hand, Alexandre Joannou, Chris
Kitching, Wojciech Koszek, Bob Laddaga, Patrick Lincoln,
Ilias Marinos, A Theodore Markettos, Ed Maste, Andrew W.
Moore, Alan Mujumdar, Prashanth Mundkur, Colin Rothwell,
Philip Paeps, Jeunese Payne, Hassen Saidi, Howie Shrobe, and
Bjoern Zeeb, our anonymous reviewers, and shepherd Frank
Piessens, for their feedback and assistance. This work is part of
the CTSRD and MRC2 projects sponsored by the Defense Advanced
Research Projects Agency (DARPA) and the Air Force
Research Laboratory (AFRL), under contracts FA8750-10-C-
0237 and FA8750-11-C-0249. The views, opinions, and/or
findings contained in this paper are those of the authors and
should not be interpreted as representing the official views
or policies, either expressed or implied, of the Department
of Defense or the U.S. Government. We acknowledge the EPSRC
REMS Programme Grant [EP/K008528/1], Isaac Newton
Trust, UK Higher Education Innovation Fund (HEIF), Thales
E-Security, and Google, Inc.This is the author accepted manuscript. The final version is available at http://dx.doi.org/10.1109/SP.2015.
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CheriRTOS: A Capability Model for Embedded Devices
Embedded systems are deployed ubiquitously
among various sectors including automotive, medical, robotics
and avionics. As these devices become increasingly connected,
the attack surface also increases tremendously; new mechanisms
must be deployed to defend against more sophisticated attacks
while not violating resource constraints. In this paper we present
CheriRTOS on CHERI-64, a hardware-software platform atop
Capability Hardware Enhanced RISC Instructions (CHERI) for
embedded systems.
Our system provides efficient and scalable task isolation,
fast and secure inter-task communication, fine-grained memory
safety, and real-time guarantees, using hardware capabilities as
the sole protection mechanism. We summarize state-of-the-art se-
curity and memory safety for embedded systems for comparison
with our platform, illustrating the superior substrate provided
by CHERI’s capabilities. Finally, our evaluations show that a
capability system can be implemented within the constraints of
embedded systems
Beyond the PDP-11: Architectural support for a memory-safe C abstract machine
We propose a new memory-safe interpretation of the C abstract machine that provides stronger protection to benefit security and debugging. Despite ambiguities in the specification intended to provide implementation flexibility, contemporary implementations of C have converged on a memory model similar to the PDP-11, the original target for C. This model lacks support for memory safety despite well documented impacts on security and reliability. Attempts to change this model are often hampered by assumptions embedded in a large body of existing C code, dating back to the memory model exposed by the original C compiler for the PDP-11. Our experience with attempting to implement a memory-safe variant of C on the CHERI experimental microprocessor led us to identify a number of problematic idioms. We describe these as well as their interaction with existing memory safety schemes and the assumptions that they make beyond the requirements of the C specification. Finally, we refine the CHERI ISA and abstract model for C, by combining elements of the CHERI capability model and fat pointers, and present a softcore CPU that implements a C abstract machine that can run legacy C code with strong memory protection guarantees.This work is part of the CTSRD and MRC2 projects that are sponsored by the Defense Advanced Research Projects Agency (DARPA) and the Air Force Research Laboratory (AFRL), under contracts FA8750-10-C-0237 and FA8750- 11-C-0249. The views, opinions, and/or findings contained in this paper are those of the authors and should not be interpreted as representing the official views or policies, either expressed or implied, of the Department of Defense or the U.S. Government. We gratefully acknowledge Google, Inc. for its sponsorship
Exploring rationales for branding a university: Should we be seeking to measure branding in UK universities?
Although branding is now widespread among UK universities, the application of branding principles in the higher education sector is comparatively recent and may be controversial for internal audiences who question its suitability and efficiency.
This paper seeks to investigate how and whether the effectiveness of branding activity in the higher education sector should be evaluated and measured, through exploratory interviews with those who often drive it; UK University marketing professionals.
Conclusions suggest that university branding is inherently complex and therefore application of commercial approaches may be over simplistic. Whilst marketing professionals discuss challenges they do not necessarily have a consistent view of the objectives of branding activity although all were able to clearly articulate branding objectives for their university, including both qualitative and, to some extent, quantitative metrics. Some measures of the real value of branding activity are therefore suggested but a key debate is perhaps whether the objectives and role of branding in higher education needs to be clarified, and a more consistent view of appropriate metrics reached? Various challenges in implementing branding approaches are also highlighted
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Efficient tagged memory
We characterize the cache behavior of an in-memory tag table and
demonstrate that an optimized implementation can typically achieve a near-zero memory traffic overhead. Both industry and academia have repeatedly demonstrated tagged memory as a key mechanism to enable enforcement of powerful security invariants, including capabilities pointer integrity, watchpoints, and information-flow tracking. A single-bit tag shadowspace is the most commonly proposed requirement, as one bit is the minimum metadata needed to distinguish between an untyped data word and any number of new hardware-enforced types. We survey various tag shadowspace approaches and identify their common requirements and positive features of their implementations. To avoid non-standard memory widths, we identify the most practical implementation for tag storage to be an in-memory table managed next to the DRAM controller. We characterize the caching performance of such a tag table and demonstrate a DRAM traffic overhead below 5\% for the vast majority of applications. We identify spatial locality on a page scale as the primary factor that enables surprisingly high table cache-ability. We then demonstrate tag-table compression for a set of common applications. A hierarchical structure with elegantly simple optimizations reduces DRAM traffic overhead to below 1\% for most applications. These insights and optimizations pave the way for commercial applications making use of single-bit tags stored in commodity memory
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