This is what is still exposed, and it allows me to control my lamps from
within home-assistant.
✗ PrivateNetwork= Service has access to the host's network 0.5
✗ RestrictAddressFamilies=~AF_(INET|INET6) Service may allocate Internet sockets 0.3
✗ DeviceAllow= Service has a device ACL with some special devices 0.1
✗ IPAddressDeny= Service does not define an IP address allow list 0.2
✗ PrivateDevices= Service potentially has access to hardware devices 0.2
✗ RootDirectory=/RootImage= Service runs within the host's root directory 0.1
✗ SupplementaryGroups= Service runs with supplementary groups 0.1
✗ MemoryDenyWriteExecute= Service may create writable executable memory mappings 0.1
→ Overall exposure level for zigbee2mqtt.service: 1.3 OK 🙂
Until now, the `touch + chmod 600 + write` approach made it possible for
an unprivileged local user read the private key file, by opening
the file after the touch, before the read permissions are restricted.
This was only the case if `generatePrivateKeyFile = true` and the parent
directory of `privateKeyFile` already existed and was readable.
This commit fixes it by using `umask`, which ensures kernel-side that
the `touch` creates the file with the correct permissions atomically.
This commit also:
* Removes `mkdir --mode 0644 -p "${dirOf values.privateKeyFile}"`
because setting permissions `drw-r--r--` ("nobody can enter that dir")
is awkward. `drwx------` would perhaps make sense, like for `.ssh`.
However, setting the permissions on the private key file is enough,
and likely better, because `privateKeyFile` is about that file
specifically and no docs suggest that there's something special
about its parent dir.
* Removes the `chmod 0400 "${values.privateKeyFile}"`
because there isn't really a point in removing write access from
the owner of the private key.
- Set an explicit umask that allows u+rwx and g+r.
- Adds `ProtectControlGroups` and `ProtectKernelLogs`, there should be
no need to access either.
- Adds `ProtectClock` to prevent write-access to the system clock.
- `ProtectProc` hides processes from other users within the /proc
filesystem and `ProcSubSet` hides all files/directories unrelated to
the process management of the units process.
- Sets `RemoveIPC`, as there is no SysV or POSIX IPC within nginx that I
know of.
- Restricts the creation of arbitrary namespaces
- Adds a reasonable `SystemCallFilter` preventing calls to @privileged,
@obsolete and others.
And finally applies some sorting based on the order these options appear
in systemd.exec(5).
See #119615 for more details. The aarch64-linux test failed with
"qemu-system-aarch64: Virtio VGA not available" so I've restricted the
test to x86_64-linux (the virtio paravirtualized 3D graphics driver is
likely only available on very few platforms).
Peter Simons