nixos/incus: add incus-user service and socket (NixOS#355645)

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

@@ -872,6 +872,8 @@
 
 - `qgis` and `qgis-ltr` are now built without `grass` by default. `grass` support can be enabled with `qgis.override { withGrass = true; }`.
 
+- `virtualisation.incus` module gained new `incus-user.service` and `incus-user.socket` systemd units. It is now possible to add a user to `incus` group instead of `incus-admin` for increased security.
+
 ## Detailed Migration Information {#sec-release-24.11-migration}
 
 ### `sound` options removal {#sec-release-24.11-migration-sound}

nixos/modules/virtualisation/incus.nix

@@ -153,7 +153,10 @@ in
 
         Users in the "incus-admin" group can interact with
         the daemon (e.g. to start or stop containers) using the
-        {command}`incus` command line tool, among others
+        {command}`incus` command line tool, among others.
+        Users in the "incus" group can also interact with
+        the daemon, but with lower permissions
+        (i.e. administrative operations are forbidden).
       '';
 
       package = lib.mkPackageOption pkgs "incus-lts" { };
@@ -359,6 +362,27 @@ in
       };
     };
 
+    systemd.services.incus-user = {
+      description = "Incus Container and Virtual Machine Management User Daemon";
+
+      inherit environment;
+
+      after = [
+        "incus.service"
+        "incus-user.socket"
+      ];
+
+      requires = [
+        "incus-user.socket"
+      ];
+
+      serviceConfig = {
+        ExecStart = "${cfg.package}/bin/incus-user --group incus";
+
+        Restart = "on-failure";
+      };
+    };
+
     systemd.services.incus-startup = lib.mkIf cfg.softDaemonRestart {
       description = "Incus Instances Startup/Shutdown";
 
@@ -391,6 +415,17 @@ in
       };
     };
 
+    systemd.sockets.incus-user = {
+      description = "Incus user UNIX socket";
+      wantedBy = [ "sockets.target" ];
+
+      socketConfig = {
+        ListenStream = "/var/lib/incus/unix.socket.user";
+        SocketMode = "0660";
+        SocketGroup = "incus";
+      };
+    };
+
     systemd.services.incus-preseed = lib.mkIf (cfg.preseed != null) {
       description = "Incus initialization with preseed file";
 
@@ -409,6 +444,7 @@ in
       };
     };
 
+    users.groups.incus = { };
     users.groups.incus-admin = { };
 
     users.users.root = {

nixos/tests/incus/incusd-options.nix

@@ -44,7 +44,7 @@ import ../make-test-python.nix (
           preseed = {
             networks = [
               {
-                name = "nixostestbr0";
+                name = "incusbr0";
                 type = "bridge";
                 config = {
                   "ipv4.address" = "10.0.100.1/24";
@@ -58,12 +58,12 @@ import ../make-test-python.nix (
                 devices = {
                   eth0 = {
                     name = "eth0";
-                    network = "nixostestbr0";
+                    network = "incusbr0";
                     type = "nic";
                   };
                   root = {
                     path = "/";
-                    pool = "nixostest_pool";
+                    pool = "default";
                     size = "35GiB";
                     type = "disk";
                   };
@@ -72,43 +72,69 @@ import ../make-test-python.nix (
             ];
             storage_pools = [
               {
-                name = "nixostest_pool";
+                name = "default";
                 driver = "dir";
               }
             ];
           };
         };
+
       };
+
       networking.nftables.enable = true;
+
+      users.users.testuser = {
+        isNormalUser = true;
+        shell = pkgs.bashInteractive;
+        group = "incus";
+        uid = 1000;
+      };
     };
 
-    testScript = ''
-      def instance_is_up(_) -> bool:
-          status, _ = machine.execute("incus exec container --disable-stdin --force-interactive /run/current-system/sw/bin/systemctl -- is-system-running")
-          return status == 0
-
-      machine.wait_for_unit("incus.service")
-      machine.wait_for_unit("incus-preseed.service")
-
-      with subtest("Container image can be imported"):
-          machine.succeed("incus image import ${container-image-metadata} ${container-image-rootfs} --alias nixos")
-
-      with subtest("Container can be launched and managed"):
-          machine.succeed("incus launch nixos container")
-          with machine.nested("Waiting for instance to start and be usable"):
-            retry(instance_is_up)
-          machine.succeed("echo true | incus exec container /run/current-system/sw/bin/bash -")
-
-      with subtest("Verify preseed resources created"):
-          machine.succeed("incus profile show default")
-          machine.succeed("incus network info nixostestbr0")
-          machine.succeed("incus storage show nixostest_pool")
-
-      with subtest("Instance is stopped when softDaemonRestart is disabled and services is stopped"):
-          pid = machine.succeed("incus info container | grep 'PID'").split(":")[1].strip()
-          machine.succeed(f"ps {pid}")
-          machine.succeed("systemctl stop incus")
-          machine.fail(f"ps {pid}")
-    '';
+    testScript = # python
+      ''
+        def wait_for_instance(name: str, project: str = "default"):
+            def instance_is_up(_) -> bool:
+                status, _ = machine.execute(f"incus exec {name} --disable-stdin --force-interactive --project {project} -- /run/current-system/sw/bin/systemctl is-system-running")
+                return status == 0
+
+            with machine.nested(f"Waiting for instance {name} to start and be usable"):
+              retry(instance_is_up)
+
+        machine.wait_for_unit("incus.service")
+        machine.wait_for_unit("incus-preseed.service")
+
+        with subtest("Container image can be imported"):
+            machine.succeed("incus image import ${container-image-metadata} ${container-image-rootfs} --alias nixos")
+
+        with subtest("Container can be launched and managed"):
+            machine.succeed("incus launch nixos instance1")
+            wait_for_instance("instance1")
+            machine.succeed("echo true | incus exec instance1 /run/current-system/sw/bin/bash -")
+
+        with subtest("Verify preseed resources created"):
+            machine.succeed("incus profile show default")
+            machine.succeed("incus network info incusbr0")
+            machine.succeed("incus storage show default")
+
+        with subtest("Instance is stopped when softDaemonRestart is disabled and services is stopped"):
+            pid = machine.succeed("incus info instance1 | grep 'PID'").split(":")[1].strip()
+            machine.succeed(f"ps {pid}")
+            machine.succeed("systemctl stop incus")
+            machine.fail(f"ps {pid}")
+
+        with subtest("incus-user allows restricted access for users"):
+            machine.fail("incus project show user-1000")
+            machine.succeed("su - testuser bash -c 'incus list'")
+            # a project is created dynamically for the user
+            machine.succeed("incus project show user-1000")
+            # users shouldn't be able to list storage pools
+            machine.fail("su - testuser bash -c 'incus storage list'")
+
+        with subtest("incus-user allows users to launch instances"):
+            machine.succeed("su - testuser bash -c 'incus image import ${container-image-metadata} ${container-image-rootfs} --alias nixos'")
+            machine.succeed("su - testuser bash -c 'incus launch nixos instance2'")
+            wait_for_instance("instance2", "user-1000")
+      '';
   }
 )