Run a systemd service with MemoryDenyWriteExecute and RestrictRealtime to harden against JIT/exploit primitives
domain: systemd · 7 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Add MemoryDenyWriteExecute=yes to the [Service] section: the service's memory mappings can be writable or executable but never both (W^X), blocking classic code-injection
Add RestrictRealtime=yes to forbid SCHED_FIFO / SCHED_RR real-time scheduling and the use of mlock/mlockall
Add LockPersonality=yes to prevent changing the process execution domain (personality(2)), and RestrictSUIDSGID=yes to block setuid/setgid binary transitions
Set SystemCallArchitectures=native and a seccomp allow-list (SystemCallFilter=@system-service) to complement the memory protections
Restart the unit (systemctl daemon-reload && systemctl restart <name>.service) and confirm the service starts cleanly
Verify with grep -E 'NoNewPrivs|Seccomp' /proc/<pid>/status and by attempting (in a lab) a writable+executable mmap which should now fail with EPERM
Watch journalctl -u <name> for SIGSYS/EPERM if a JIT (V8, JVM C2, etc.) needs W+X regions
Known gotchas
MemoryDenyWriteExecute=yes breaks JIT compilers (Node/V8, JVM JIT, CPython is fine) that need writable executable memory - either disable JIT for that process or drop W^X for it
RestrictRealtime=yes also blocks mlock, which some low-latency/audio workloads rely on - if the service legitimately needs realtime scheduling, exclude it from this hardening
These flags are best-effort guarantees enforced by prctl/seccomp; they compose with NoNewPrivileges=yes and an allow-list syscall filter for defense in depth
LockPersonality=yes can break tools that call personality() to change the ABI (e.g. 32-bit compat apps)
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