Hardening Linux guest kernel for CC
summary
Argues that guest kernels must treat host-exposed reads as hostile, points to many MMIO/MSR/PCIe read sites in the 5.11 kernel and dozens of drivers doing probing during probe, and proposes a runtime device filter / allow-list that prevents unapproved drivers from running in confidential VMs. Supplies a practical path: upstreamable patches for filtering, a virtio fuzzing toolset and hardening methodology for the allowed drivers, and notes remaining technical objections and tradeoffs versus attestation or minimal kernel images.
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chapters (6)
- 0:00Introduction and motivation
- 3:12New attack surface in drivers
- 7:04Threat model and cost-benefit debate
- 11:39Alternatives to driver disabling
- 16:35Device filter approach discussion
- 19:45Q&A and wrap-up
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