#snapsafe: restoring uniqueness in Virtual Machine clones
summary
Problem: VM snapshots duplicate per-VM state like RNG seeds and host keys. Proposal adds a vmgenid generation counter (word-sized) and exposes it to user space via mmap and poll interface so userland PRNGs can detect post‑snapshot changes race‑free; kernel RNG can recheck the 16‑byte vmgenid to avoid races. Systemd integration models a quieting/quiet pre‑snapshot state with inhibitor locks to drain network and restart services (sshd) after reseed. Implementation is prototyped and discussed; race windows and policy choices remain unsolved.
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chapters (4)
- 0:00Introduction and problem definition
- 3:55Current Linux mechanisms
- 17:43System-wide snapshot safety
- 39:55Summary and next steps
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