pam_mount module: integrate pam_mount into PAM of NixOS

nixos/modules/config/users-groups.nix

@@ -108,6 +108,15 @@ let
         description = "The user's home directory.";
       };
 
+      cryptHomeLuks = mkOption {
+        type = with types; nullOr str;
+        default = null;
+        description = ''
+          Path to encrypted luks device that contains
+          the user's home directory.
+        '';
+      };
+
       shell = mkOption {
         type = types.str;
         default = "/run/current-system/sw/bin/nologin";

nixos/modules/module-list.nix

@@ -84,6 +84,7 @@
   ./security/grsecurity.nix
   ./security/pam.nix
   ./security/pam_usb.nix
+  ./security/pam_mount.nix
   ./security/polkit.nix
   ./security/prey.nix
   ./security/rngd.nix

nixos/modules/security/pam.nix

@@ -126,6 +126,14 @@ let
         '';
       };
 
+      pamMount = mkOption {
+        default = config.security.pam.mount.enable;
+        type = types.bool;
+        description = ''
+          Enable PAM mount (pam_mount) system to mount fileystems on user login.
+        '';
+      };
+
       allowNullPassword = mkOption {
         default = false;
         type = types.bool;
@@ -224,7 +232,9 @@ let
           ${optionalString cfg.usbAuth
               "auth sufficient ${pkgs.pam_usb}/lib/security/pam_usb.so"}
           ${optionalString cfg.unixAuth
-              "auth ${if config.security.pam.enableEcryptfs then "required" else "sufficient"} pam_unix.so ${optionalString cfg.allowNullPassword "nullok"} likeauth"}
+              "auth ${if (config.security.pam.enableEcryptfs || cfg.pamMount) then "required" else "sufficient"} pam_unix.so ${optionalString cfg.allowNullPassword "nullok"} likeauth"}
+          ${optionalString cfg.pamMount
+              "auth optional ${pkgs.pam_mount}/lib/security/pam_mount.so"}
           ${optionalString config.security.pam.enableEcryptfs
               "auth required ${pkgs.ecryptfs}/lib/security/pam_ecryptfs.so unwrap"}
           ${optionalString cfg.otpwAuth
@@ -238,12 +248,14 @@ let
             auth [default=die success=done] ${pam_ccreds}/lib/security/pam_ccreds.so action=validate use_first_pass
             auth sufficient ${pam_ccreds}/lib/security/pam_ccreds.so action=store use_first_pass
           ''}
-          ${optionalString (! config.security.pam.enableEcryptfs) "auth required pam_deny.so"}
+          ${optionalString (!(config.security.pam.enableEcryptfs || cfg.pamMount)) "auth required pam_deny.so"}
 
           # Password management.
           ${optionalString config.security.pam.enableEcryptfs
               "password optional ${pkgs.ecryptfs}/lib/security/pam_ecryptfs.so"}
           password requisite pam_unix.so nullok sha512
+          ${optionalString cfg.pamMount
+              "password optional ${pkgs.pam_mount}/lib/security/pam_mount.so"}
           ${optionalString config.users.ldap.enable
               "password sufficient ${pam_ldap}/lib/security/pam_ldap.so"}
           ${optionalString config.krb5.enable
@@ -280,6 +292,8 @@ let
               "session required ${pkgs.pam}/lib/security/pam_limits.so conf=${makeLimitsConf cfg.limits}"}
           ${optionalString (cfg.showMotd && config.users.motd != null)
               "session optional ${pkgs.pam}/lib/security/pam_motd.so motd=${motd}"}
+          ${optionalString cfg.pamMount
+              "session optional ${pkgs.pam_mount}/lib/security/pam_mount.so"}
         '';
     };
 

nixos/modules/security/pam_mount.nix

@@ -0,0 +1,72 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.security.pam.mount;
+
+  anyPamMount = any (attrByPath ["pamMount"] false) (attrValues config.security.pam.services);
+in
+
+{
+  options = {
+
+    security.pam.mount = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Enable PAM mount system to mount fileystems on user login.
+        '';
+      };
+
+      extraVolumes = mkOption {
+        type = types.listOf types.str;
+        default = [];
+        description = ''
+          List of volume definitions for pam_mount.
+          For more information, visit <link
+          xlink:href="http://pam-mount.sourceforge.net/pam_mount.conf.5.html" />.
+        '';
+      };
+    };
+
+  };
+
+  config = mkIf (cfg.enable || anyPamMount) {
+
+    environment.systemPackages = [ pkgs.pam_mount ];
+    environment.etc = [{
+      target = "security/pam_mount.conf.xml";
+      source =
+        let
+          extraUserVolumes = filterAttrs (n: u: u.cryptHomeLuks != null) config.users.extraUsers;
+          userVolumeEntry = user: "<volume user=\"${user.name}\" path=\"${user.cryptHomeLuks}\" mountpoint=\"${user.home}\" />\n";
+        in
+         pkgs.writeText "pam_mount.conf.xml" ''
+          <?xml version="1.0" encoding="utf-8" ?>
+          <!DOCTYPE pam_mount SYSTEM "pam_mount.conf.xml.dtd">
+          <!-- auto generated from Nixos: modules/config/users-groups.nix -->
+          <pam_mount>
+          <debug enable="0" />
+
+          ${concatStrings (map userVolumeEntry (attrValues extraUserVolumes))}
+          ${concatStringsSep "\n" cfg.extraVolumes}
+
+          <!-- if activated, requires ofl from hxtools to be present -->
+          <logout wait="0" hup="no" term="no" kill="no" />
+          <!-- set PATH variable for pam_mount module -->
+          <path>${pkgs.utillinux}/bin</path>
+          <!-- create mount point if not present -->
+          <mkmountpoint enable="1" remove="true" />
+
+          <!-- specify the binaries to be called -->
+          <cryptmount>${pkgs.pam_mount}/bin/mount.crypt %(VOLUME) %(MNTPT)</cryptmount>
+          <cryptumount>${pkgs.pam_mount}/bin/umount.crypt %(MNTPT)</cryptumount>
+          <pmvarrun>${pkgs.pam_mount}/bin/pmvarrun -u %(USER) -o %(OPERATION)</pmvarrun>
+          </pam_mount>
+          '';
+    }];
+
+  };
+}