Computer Laboratory

Khilan Gudka

I am a Research Associate in the Security Group at the University of Cambridge Computer Laboratory. Prior to this, I completed my PhD at the Department of Computing, Imperial College London. You can find my old page here for reference purposes.

Research interests

  • Application compartmentalisation
  • Static/dynamic program analysis
  • Compilers/runtimes
  • Capability systems
  • Concurrency

Projects

SOAAP

Sandboxing technologies such as Capsicum and CHERI support the fine-grained compartmentalisation of large-scale applications such as web browsers and office suites, as well as multiple-component software such as the UNIX userspace. When deployed correctly, application compartmentalisation offers significant benefits by allowing policies to be imposed within applications, and in mitigating exploited vulnerabilities. However, application compartmentalisation remains an art rather than a science: identifying, implementing, and debugging partitioning strategies requires detailed expertise in both the application and security. SOAAP is exploring semi-automated techniques, grounded in static analysis, dynamic analysis, and automated program transformation, to improve the developer experience. This project is jointly funded by Google and DARPA, and takes place within the context of the CTSRD project.

CHERI

This project is an outgrowth of our earlier Capsicum project, which explored hybrid capability models in the context of UNIX operating system design. While a successful project, we identified a number of limitations to current CPU designs that made application compartmentalisation tricky, despite enhanced operating system support. CHERI is a hardware-software interface research project seeking to revise ISA design in order to better support software compartmentalisation. CHERI transposes the Capsicum hybrid capability model into the CPU architecture space, allowing fine-grained compartmentalisation within process address spaces – while continuing to support current software designs.

We are developing a prototype of the CHERI ISA using the Bluespec Extensible RISC Implementation (BERI), a 64-bit MIPS FPGA soft core implemented in the Bluespec HDL. The FreeBSD operating system, with Capsicum support, has also been ported to CHERI in order to allow us to compare, side-by-side, traditional software compartmentalisation approaches (based on a translation look-aside buffer (TLB)), with those supported by a capability coprocessor. Using commodity software stacks, such as FreeBSD, LLVM, and the Chromium web browser, allows us to validate our hybrid design, applying capability-based compartmentalisation selectively to support both our most trusted (OS kernel, low-level language runtimes), and least trustworthy (web browsers and servers), software components.

TESLA

TESLA builds on our experiences developing the TrustedBSD MAC Framework and Capsicum: our most critical security properties are frequently safety (temporal) properties rather than static invariants. Current tools for testing temporal properties are largely static, and unable to work effectively on extremely large C-language software bases, such as multi-million lines-of-code operating system kernels and web browsers. TESLA borrows ideas from model checking, applying them in a dynamic context using compiler-assisted instrumentation to continuously validate temporal security assertions during software execution. We have implemented a prototype of TESLA based on clang/LLVM AST transforms, which is able to test both explicit automata against C implementations (such as protocol state machines in the kernel and OpenSSL) and inline assertions checking for missing access control checks in OS logic.

Publications

Contact details


Post

Khilan Gudka
Computer Laboratory
15 JJ Thomson Avenue
Cambridge CB3 0FD
United Kingdom

Email

[firstname].[lastname]@cl.cam.ac.uk

Phone

+44 (0) 1223 763 602