macOS sandbox blocks ps-backed recording process identity

[janicduplessis]

Purpose

Allow iOS simulator recording to establish and verify process ownership inside a macOS sandbox that refuses execution of /bin/ps.

Reproduction

Run a synthetic Node child-process identity query under sandbox-exec -p '(version 1)(allow default)'. On macOS where /bin/ps is setuid, its execution is refused. readProcessStartTime and readProcessCommand return null, and recording startup can fail with simctl recordVideo did not expose a complete process identity.

The shared host-process module currently shells out to ps. A non-privileged native probe using proc_pidinfo(PROC_PIDTBSDINFO) and sysctl(KERN_PROCARGS2) can read the same owned child under this policy. PROC_PIDTBSDINFO needs a nonzero argument to include zombie processes.

Required behavior

• Keep command/start-time ownership checks and fail closed when identity cannot be proven; do not replace ownership with PID liveness alone.
• Bound native reads and preserve argument boundaries before rendering the existing command string.
• Detect changed start identity, zombie state, permission refusal, and exited processes.
• Package the native implementation without a global installation and keep non-macOS behavior unchanged.

Completion evidence

Real sandbox tests on synthetic owned children, malformed/bounded parsing tests, and iOS recording start/stop with a nonempty playable artifact. No benchmark transcripts or private run results are needed.