Practical DIFC Enforcement on Android
summary
Weir implements lazy polyinstantiation and domain declassification on Android 5.0.1 to give app-level secrecy without breaking unmodified apps. It creates context-specific process and file-layer instances, integrates with the Flume policy model, and runs open-source. Measured overhead is under 4 ms for component startup; starting the 200th instance adds ~50 ms. A K-9 email + bcloud case enforces a bcloud.com-only export policy successfully. Remaining problems: instance-explosion DoS and stale copies from per-label copy‑on‑write storage.
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chapters (14)
- 0:00Start
- 0:20The "new" Modern Operating Systems
- 1:05Example use case - Email
- 4:25DIFC for Android
- 7:10C2. Label Propagation
- 11:33C3. Network Declassification
- 15:55Practicality of Polyinstantiation
- 17:53Why this works?
- 19:09Domain Declassification
- 19:48Implementation & Performance
- 20:06Evaluation: Microbenchmarks
- 21:04Case Study - K9 Email
- 23:13Caveats
- 24:21Closing Remarks
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