hive-c0re runs as the unprivileged hive-core user and delegates all
privileged operations to hive-priv via a Unix socket. Add the subset of
systemd sandboxing directives that are provably safe without a watched
deploy (no ProtectSystem / RestrictAddressFamilies, which require mapping
the full set of filesystem/network paths first):
- NoNewPrivileges: already unprivileged; no setuid/capability escalation
- PrivateTmp: nix subprocesses use StateDirectory temp paths, not /tmp
- ProtectHome: HOME is /var/lib/hyperhive (StateDirectory), not /home/*
- ProtectKernelTunables: no sysctl writes needed
- ProtectKernelLogs: logs via systemd-journal group, not /dev/kmsg
- ProtectControlGroups: cgroup writes go through hive-priv, not c0re
- RestrictNamespaces: namespace creation goes through hive-priv
- LockPersonality: no personality changes needed
- RestrictRealtime: no real-time scheduling
Follows the same pattern as hive-priv (PrivateTmp + ProtectHome already
present there). Deferred: ProtectSystem=strict + ReadWritePaths +
RestrictAddressFamilies — those need a watched deploy per the #1845 plan
since getting the ReadWritePaths wrong silently breaks runtime I/O.
b3b1c7b288