Procfs
ProtectKernelTunables setting
Restrict systemd units to access information from the kernel tunables in the /proc and /sys directories with the unit setting ProtectKernelTunables.
ProcSubset setting
Restrict systemd units to access information from the /proc directory with the unit setting ProcSubset.
ProtectProc setting
Restrict systemd units to access information from the /proc directory with the unit setting ProtectProc.