openssh: support prohibit-password for permitRootLogin

See 1dc8d93ce6

I also made it the default.

nixos/modules/services/networking/ssh/sshd.nix

@@ -102,8 +102,8 @@ in
       };
 
       permitRootLogin = mkOption {
-        default = "without-password";
-        type = types.enum ["yes" "without-password" "forced-commands-only" "no"];
+        default = "prohibit-password";
+        type = types.enum ["yes" "without-password" "prohibit-password" "forced-commands-only" "no"];
         description = ''
           Whether the root user can login using ssh.
         '';

nixos/modules/virtualisation/amazon-image.nix

@@ -138,7 +138,7 @@ let cfg = config.ec2; in
     # Allow root logins only using the SSH key that the user specified
     # at instance creation time.
     services.openssh.enable = true;
-    services.openssh.permitRootLogin = "without-password";
+    services.openssh.permitRootLogin = "prohibit-password";
 
     # Force getting the hostname from EC2.
     networking.hostName = mkDefault "";

nixos/modules/virtualisation/azure-common.nix

@@ -24,7 +24,7 @@ with lib;
   # Allow root logins only using the SSH key that the user specified
   # at instance creation time, ping client connections to avoid timeouts
   services.openssh.enable = true;
-  services.openssh.permitRootLogin = "without-password";
+  services.openssh.permitRootLogin = "prohibit-password";
   services.openssh.extraConfig = ''
     ClientAliveInterval 180
   '';

nixos/modules/virtualisation/brightbox-image.nix

@@ -103,7 +103,7 @@ in
   # Allow root logins only using the SSH key that the user specified
   # at instance creation time.
   services.openssh.enable = true;
-  services.openssh.permitRootLogin = "without-password";
+  services.openssh.permitRootLogin = "prohibit-password";
 
   # Force getting the hostname from Google Compute.
   networking.hostName = mkDefault "";

nixos/modules/virtualisation/google-compute-image.nix

@@ -111,7 +111,7 @@ in
   # Allow root logins only using the SSH key that the user specified
   # at instance creation time.
   services.openssh.enable = true;
-  services.openssh.permitRootLogin = "without-password";
+  services.openssh.permitRootLogin = "prohibit-password";
   services.openssh.passwordAuthentication = mkDefault false;
 
   # Force getting the hostname from Google Compute.

nixos/modules/virtualisation/nova-image.nix

@@ -31,7 +31,7 @@ with lib;
 
   # Allow root logins
   services.openssh.enable = true;
-  services.openssh.permitRootLogin = "without-password";
+  services.openssh.permitRootLogin = "prohibit-password";
 
   # Put /tmp and /var on /ephemeral0, which has a lot more space.
   # Unfortunately we can't do this with the `fileSystems' option