nixos/pam/u2f: implement RFC0042

This module has a lot of options, so it's a good candidate for freeform
settings.

nixos/doc/manual/release-notes/rl-2411.section.md

@@ -197,6 +197,9 @@
   The derivation now installs "impl" headers selectively instead of by a wildcard.
   Use `imgui.src` if you just want to access the unpacked sources.
 
+- `security.pam.u2f` now follows RFC42.
+  All module options are now settable through the freeform `.settings`.
+
 - Cinnamon has been updated to 6.2.
   - Following Mint 22 defaults, the Cinnamon module no longer ships geary and hexchat by default.
   - Nemo is now built with gtk-layer-shell support, note that for now it will be expected to see nemo-desktop

nixos/modules/security/pam.nix

@@ -7,6 +7,13 @@ with lib;
 
 let
 
+  moduleSettingsType = with types; attrsOf (nullOr (oneOf [ bool str int pathInStore ]));
+  moduleSettingsDescription = ''
+    Boolean values render just the key if true, and nothing if false.
+    Null values are ignored.
+    All other values are rendered as key-value pairs.
+  '';
+
   mkRulesTypeOption = type: mkOption {
     # These options are experimental and subject to breaking changes without notice.
     description = ''
@@ -71,12 +78,12 @@ let
           '';
         };
         settings = mkOption {
-          type = with types; attrsOf (nullOr (oneOf [ bool str int pathInStore ]));
+          type = moduleSettingsType;
           default = {};
           description = ''
             Settings to add as `module-arguments`.
 
-            Boolean values render just the key if true, and nothing if false. Null values are ignored. All other values are rendered as key-value pairs.
+            ${moduleSettingsDescription}
           '';
         };
       };
@@ -660,11 +667,7 @@ let
           (let p11 = config.security.pam.p11; in { name = "p11"; enable = cfg.p11Auth; control = p11.control; modulePath = "${pkgs.pam_p11}/lib/security/pam_p11.so"; args = [
             "${pkgs.opensc}/lib/opensc-pkcs11.so"
           ]; })
-          (let u2f = config.security.pam.u2f; in { name = "u2f"; enable = cfg.u2fAuth; control = u2f.control; modulePath = "${pkgs.pam_u2f}/lib/security/pam_u2f.so"; settings = {
-            inherit (u2f) debug interactive cue origin;
-            authfile = u2f.authFile;
-            appid = u2f.appId;
-          }; })
+          (let u2f = config.security.pam.u2f; in { name = "u2f"; enable = cfg.u2fAuth; control = u2f.control; modulePath = "${pkgs.pam_u2f}/lib/security/pam_u2f.so"; inherit (u2f) settings; })
           (let ussh = config.security.pam.ussh; in { name = "ussh"; enable = config.security.pam.ussh.enable && cfg.usshAuth; control = ussh.control; modulePath = "${pkgs.pam_ussh}/lib/security/pam_ussh.so"; settings = {
             ca_file = ussh.caFile;
             authorized_principals = ussh.authorizedPrincipals;
@@ -952,6 +955,12 @@ in
   imports = [
     (mkRenamedOptionModule [ "security" "pam" "enableU2F" ] [ "security" "pam" "u2f" "enable" ])
     (mkRenamedOptionModule [ "security" "pam" "enableSSHAgentAuth" ] [ "security" "pam" "sshAgentAuth" "enable" ])
+    (mkRenamedOptionModule [ "security" "pam" "u2f" "authFile" ] [ "security" "pam" "u2f" "settings" "authfile" ])
+    (mkRenamedOptionModule [ "security" "pam" "u2f" "appId" ] [ "security" "pam" "u2f" "settings" "appid" ])
+    (mkRenamedOptionModule [ "security" "pam" "u2f" "origin" ] [ "security" "pam" "u2f" "settings" "origin" ])
+    (mkRenamedOptionModule [ "security" "pam" "u2f" "debug" ] [ "security" "pam" "u2f" "settings" "debug" ])
+    (mkRenamedOptionModule [ "security" "pam" "u2f" "interactive" ] [ "security" "pam" "u2f" "settings" "interactive" ])
+    (mkRenamedOptionModule [ "security" "pam" "u2f" "cue" ] [ "security" "pam" "u2f" "settings" "cue" ])
   ];
 
   ###### interface
@@ -1144,7 +1153,26 @@ in
         '';
       };
 
-      authFile = mkOption {
+      control = mkOption {
+        default = "sufficient";
+        type = types.enum [ "required" "requisite" "sufficient" "optional" ];
+        description = ''
+          This option sets pam "control".
+          If you want to have multi factor authentication, use "required".
+          If you want to use U2F device instead of regular password, use "sufficient".
+
+          Read
+          {manpage}`pam.conf(5)`
+          for better understanding of this option.
+        '';
+      };
+
+      settings = mkOption {
+        type = types.submodule {
+          freeformType = moduleSettingsType;
+
+          options = {
+            authfile = mkOption {
               default = null;
               type = with types; nullOr path;
               description = ''
@@ -1165,7 +1193,7 @@ in
               '';
             };
 
-      appId = mkOption {
+            appid = mkOption {
               default = null;
               type = with types; nullOr str;
               description = ''
@@ -1195,20 +1223,6 @@ in
               '';
             };
 
-      control = mkOption {
-        default = "sufficient";
-        type = types.enum [ "required" "requisite" "sufficient" "optional" ];
-        description = ''
-          This option sets pam "control".
-          If you want to have multi factor authentication, use "required".
-          If you want to use U2F device instead of regular password, use "sufficient".
-
-          Read
-          {manpage}`pam.conf(5)`
-          for better understanding of this option.
-        '';
-      };
-
             debug = mkOption {
               default = false;
               type = types.bool;
@@ -1239,6 +1253,21 @@ in
               '';
             };
           };
+        };
+        default = { };
+        example = {
+          authfile = "/etc/u2f_keys";
+          authpending_file = "";
+          userpresence = 0;
+          pinverification = 1;
+        };
+        description = ''
+          Options to pass to the PAM module.
+
+          ${moduleSettingsDescription}
+        '';
+      };
+    };
 
     security.pam.ussh = {
       enable = mkOption {

nixos/tests/pam/pam-u2f.nix

@@ -7,12 +7,16 @@ import ../make-test-python.nix ({ ... }:
     { ... }:
     {
       security.pam.u2f = {
+        enable = true;
         control = "required";
+        settings = {
           cue = true;
           debug = true;
-        enable = true;
           interactive = true;
           origin = "nixos-test";
+          # Freeform option
+          userpresence = 1;
+        };
       };
     };
 
@@ -20,7 +24,7 @@ import ../make-test-python.nix ({ ... }:
     ''
       machine.wait_for_unit("multi-user.target")
       machine.succeed(
-          'egrep "auth required .*/lib/security/pam_u2f.so.*cue.*debug.*interactive.*origin=nixos-test" /etc/pam.d/ -R'
+          'egrep "auth required .*/lib/security/pam_u2f.so.*cue.*debug.*interactive.*origin=nixos-test.*userpresence=1" /etc/pam.d/ -R'
       )
     '';
 })