systemd: switch to deny-everything-by-default (TemporaryFileSystem=/) with explicit BindReadOnlyPaths + BindPaths allowlist

static/Raccoon/nginx.service

@@ -15,10 +15,37 @@ ExecStop=/bin/sh -c "/bin/kill -s QUIT $(/bin/cat /run/nginx.pid)"
 TimeoutStartSec=10
 LimitNOFILE=65535
 
-# === hardening (compatible with LuaJIT + nginx workers + raweb agent) ===
+# === hardening: deny-everything by default, allowlist via bind mounts ===
+# TemporaryFileSystem=/ replaces the visible filesystem with an empty tmpfs.
+# Everything not bind-mounted below is invisible to nginx workers — even
+# read access. Compromise of a worker can no longer enumerate /etc/passwd,
+# /home/*, /var/lib/*, /root, /opt, etc.
+TemporaryFileSystem=/
+
+# Read-only: nginx binary, dynamic linker, all linked libs, system config,
+# CA bundles, Let's Encrypt certs (live/ + archive/ both under /etc).
+BindReadOnlyPaths=/usr
+BindReadOnlyPaths=/lib
+BindReadOnlyPaths=/lib64
+BindReadOnlyPaths=/bin
+BindReadOnlyPaths=/sbin
+BindReadOnlyPaths=/etc
+
+# Read-only: vhost docroots + app projects. Add a new line here when you
+# add a vhost whose root isn't under one of these parents.
+BindReadOnlyPaths=/raweb
+BindReadOnlyPaths=/srv
+BindReadOnlyPaths=/hostdata
+
+# Read-write: nginx runtime state.
+#   /run               nginx.pid, nginx.lock, /run/nginx/temp/*, PHP-FPM sock
+#   /var/log/nginx     access.log, error.log
+#   /nginx             config dir (read-mostly but reload writes some state)
+BindPaths=/run
+BindPaths=/var/log/nginx
+BindPaths=/nginx
+
 NoNewPrivileges=true
-ProtectSystem=strict
-ProtectHome=true
 ProtectKernelTunables=true
 ProtectKernelModules=true
 ProtectKernelLogs=true
@@ -35,16 +62,11 @@ LockPersonality=true
 SystemCallArchitectures=native
 SystemCallFilter=@system-service
 SystemCallErrorNumber=EPERM
-# ProtectSystem=strict makes the entire filesystem read-only EXCEPT these.
-# /run covers nginx.pid, nginx.lock, and the temp/ subdir (all tmpfs).
-ReadWritePaths=/run /var/log/nginx /nginx /hostdata
-# Read-only paths nginx legitimately accesses. ProtectSystem=strict already
-# allows reads everywhere by default — these are documented for the operator's
-# benefit (and so they survive future hardening tightening).
-ReadOnlyPaths=/raweb /srv /etc/letsencrypt
+
 # NOTE deliberately OFF:
 #   MemoryDenyWriteExecute=true       breaks LuaJIT (JIT writable+executable pages)
 #   SystemCallFilter=~@resources      breaks nginx workers' prlimit64()
+# ProtectSystem and ProtectHome are redundant under TemporaryFileSystem=/.
 
 [Install]
 WantedBy=multi-user.target