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_confine

_confine

Self-confinement floor for shield's long-lived state reader.

shield watch reads only its per-container state_dir — dnsmasq and audit logs, the domain cache, the DNS-tier marker — plus the shared runtime it imports from. It writes nothing outside state_dir. Before the loop starts, the reader pins itself to that lane: terok-util's process-hardening floor plus Landlock filesystem confinement. A bug in the reader then cannot read another container's state and cannot write outside its own lane. NFLOG is a netlink socket, not a filesystem access, so confinement leaves it untouched.

shield simple-clearance is deliberately outside this policy: it is a controller that invokes Podman and verdict subprocesses, not a state-only reader.

confine_to_state(state_dir)

Harden this process and pin its filesystem to state_dir plus system reads.

Applies terok-util's hardening floor, then Landlock-confines the process: read and execute the system roots, read and write only state_dir. Both steps are best-effort and never raise. An old kernel may apply only its supported subset, or may leave the daemon unconfined. The reader logs either outcome at debug level and starts anyway.

Source code in src/terok_shield/_confine.py 
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def confine_to_state(state_dir: Path) -> None:
    """Harden this process and pin its filesystem to *state_dir* plus system reads.

    Applies terok-util's hardening floor, then Landlock-confines the process:
    read and execute the system roots, read and write only *state_dir*.  Both
    steps are best-effort and never raise.  An old kernel may apply only its
    supported subset, or may leave the daemon unconfined.  The reader logs
    either outcome at debug level and starts anyway.
    """
    report = harden_self()
    if not report.fully_hardened:
        _logger.debug("shield reader hardening partial: %s", report)
    fs = confine_filesystem(_SYSTEM_READ_ROOTS, [state_dir])
    if fs.partially_confined:
        _logger.debug("shield reader filesystem-confinement partially applied: %s", fs.reason)
    elif not fs.confined:
        _logger.debug("shield reader filesystem-confinement not applied: %s", fs.reason)