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Clang randstruct Requirements

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Jordan Cantrell edited this page Nov 19, 2018 · 3 revisions

  1. Introductions

    • Tim Pugh
    • Jeff Takahashi
    • Connor Kuehl
    • Kees Cook

  2. Background

  3. Capacity

    • Availability still 1pm-5pm
    • Teams schedule varies

  4. Announce project on mailing list?

    • Avoid duplicated labor
    • Possibly solicit advice

  5. Full Randomization

    • All structures marked with "__randomize_layout" have their field positions randomized, including bit fields.
      • Reproducible random number (same seed needs to be saved as part of the build)
      • Programs report field location manually (structure layout in gcc happens before plugin invocation)
        • Keep an eye out for sassy gdb

  6. Performance-sensitive randomization (possible stretch)

    • Best-effort limit randomization to cache-line (64 byte) size regions, keep adjacent bit-fields together.

  7. Automatic structure selection (possible stretch)

    • Find structures that should be automatically selected (for example, structures of entirely function pointers), disabled with "__no_randomize_layout".

  8. Regression tests

    • Since the randomization must be stable from source-to-source, the randomization seed needs to be externally recorded (i.e. it is a build artifact).
    • Regression tests to check all the corner cases should be built and included in the implementation (i.e. hooked to the standard LLVM/Clang regression tests)

  9. Publish this, regardless of upstream acceptance

  10. Goal: upstream in LLVM/Clang!

    • Submit work upstream for review
    • Implement changes based on feedback
    • Repeat until accepted into LLVM/Clang upstream

  11. Kees -- possibly assist in finding right person to ask a question to in the event of us getting blocked

Full Random → Regression testing → upstream Automatic structure selection → performance randomization

Sign off:

Sponsor: Kees Cook

Team lead: Tim Pugh

Member: Connor Kuehl

Member: Jeff Takahashi

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