Update systemd.service to improve sandboxing.

conf/systemd.service

@@ -22,19 +22,45 @@ WorkingDirectory=__FINALPATH__/live/
 ExecStart=__FINALPATH__/live/bin/pleroma start
 ExecStop=__FINALPATH__/live/bin/pleroma stop
 
-; Some security directives.
+# Sandboxing options to harden security
-; Use private /tmp and /var/tmp folders inside a new file system namespace, which are discarded after the process stops.
+# Depending on specificities of your service/app, you may need to tweak these
-PrivateTmp=true
+# .. but this should be a good baseline
-; The /home, /root, and /run/user folders can not be accessed by this service anymore. If your Pleroma user has its home folder in one of the restricted places, or use one of these folders as its working directory, you have to set this to false.
+# Details for these options: https://www.freedesktop.org/software/systemd/man/systemd.exec.html
-ProtectHome=false
-; Mount /usr, /boot, and /etc as read-only for processes invoked by this service.
-ProtectSystem=full
-; Sets up a new /dev mount for the process and only adds API pseudo devices like /dev/null, /dev/zero or /dev/random but not physical devices. Disabled by default because it may not work on devices like the Raspberry Pi.
-PrivateDevices=false
 ; Ensures that the service process and all its children can never gain new privileges through execve().
-NoNewPrivileges=true
+NoNewPrivileges=yes
-; Drops the sysadmin capability from the daemon.
+# Use private /tmp and /var/tmp folders inside a new file system namespace, which are discarded after the process stops.
-CapabilityBoundingSet=~CAP_SYS_ADMIN
+PrivateTmp=yes
+# Sets up a new /dev mount for the process and only adds API pseudo devices like /dev/null, /dev/zero or /dev/random but not physical devices. Disabled by default because it may not work on devices like the Raspberry Pi.
+PrivateDevices=yes
+RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6 AF_NETLINK
+RestrictNamespaces=yes
+RestrictRealtime=yes
+DevicePolicy=closed
+ProtectClock=yes
+ProtectHostname=yes
+ProtectProc=invisible
+# Mount /usr, /boot, and /etc as read-only for processes invoked by this service.
+ProtectSystem=full
+# The /home, /root, and /run/user folders can not be accessed by this service anymore. If your Akkoma user has its home folder in one of the restricted places, or use one of these folders as its working directory, you have to set this to false.
+ProtectHome=false
+ProtectControlGroups=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+LockPersonality=yes
+SystemCallArchitectures=native
+SystemCallFilter=~@clock @debug @module @mount @obsolete @reboot @setuid @swap @cpu-emulation @privileged
+
+# Denying access to capabilities that should not be relevant for webapps
+# Doc: https://man7.org/linux/man-pages/man7/capabilities.7.html
+CapabilityBoundingSet=~CAP_RAWIO CAP_MKNOD
+CapabilityBoundingSet=~CAP_AUDIT_CONTROL CAP_AUDIT_READ CAP_AUDIT_WRITE
+CapabilityBoundingSet=~CAP_SYS_BOOT CAP_SYS_TIME CAP_SYS_MODULE CAP_SYS_PACCT
+CapabilityBoundingSet=~CAP_LEASE CAP_LINUX_IMMUTABLE CAP_IPC_LOCK
+CapabilityBoundingSet=~CAP_BLOCK_SUSPEND CAP_WAKE_ALARM
+CapabilityBoundingSet=~CAP_SYS_TTY_CONFIG
+CapabilityBoundingSet=~CAP_MAC_ADMIN CAP_MAC_OVERRIDE
+CapabilityBoundingSet=~CAP_NET_ADMIN CAP_NET_BROADCAST CAP_NET_RAW
+CapabilityBoundingSet=~CAP_SYS_ADMIN CAP_SYS_PTRACE CAP_SYSLOG
 
 [Install]
 WantedBy=multi-user.target