The tracking.log read was still returning empty under enforcing with NO AVC —
the tell of a DAC (not SELinux) denial. Root cause: /var/log/chrony is mode
0750 chrony:chrony (others have no access), so the agent's DynamicUser (group
tss only) can't even traverse the directory to reach the 0644 tracking.log —
EACCES on open, which produces no audit record. Manager confirmed genuinely on
fleet-manager-1db3977 (chrony-capable), and uptime flowed while chrony didn't,
proving the agent was sending empty chrony (failed read), not a manager gap.
Earlier manual reads worked only as root (sudo) or because fleetadmin had been
usermod'd into chrony during the socket test (reverted on reboot — /etc/group
is on the volatile overlay).
Fix: SupplementaryGroups=tss chrony on the unit — the chrony group has r-x on
the 0750 dir so the agent can traverse it; the log file is world-readable. This
is the DAC half; the fleet_agent_chronylog SELinux module (02a6621) is the TE
half — BOTH are required (verified: group-only -> TE-denied; module-only ->
DAC-denied silently). Corrected the now-stale 'no group' code comment; recorded
the two-layer requirement in the .te and stig-deviations #16. Needs a
workstation image rebuild + reboot.
The tracking.log approach (4ca0b6d) works in permissive but is blocked under
enforcing: chrony's log is labeled chronyd_var_log_t, confined by the shipped
policy to chronyd_t despite the 0644 mode. Verified on comet-beacon-54 — a
non-root read succeeds permissive, but under enforcing even a STIG-confined
admin (staff_t) gets Permission denied (ls -Z on the file is itself blocked).
The agent runs unconfined_service_t (confirmed via ps -eZ) and is denied the
same way.
Ship a minimal read-only allow module (files/stig/fleet-agent-chronylog.te):
allow unconfined_service_t chronyd_var_log_t:file { open read getattr } + dir
search to reach it. No write, no other chrony access, and no domain transition
(the agent reads a file; it does not exec chronyc) — narrower than the
abandoned nnp-transition module. Built + semodule -i'd in 2c-STIG alongside the
existing chrony_dhcp_dispatcher / fapolicyd_tmpfs modules. docs/stig-deviations
#16. Needs a workstation image rebuild + reboot; same policy-store-rebuild
reproducibility re-check as #14/#15.
Audiobuzz