feat: support builtin kernel mods

This PR adds the combination of dynamic and builtin kernel modules into
one feature called `kernel.enabledmodule`. It's a superset of the
`kernel.loadedmodule` feature.

Signed-off-by: AhmedGrati <ahmedgrati1999@gmail.com>

deployment/components/common/worker-mounts-combined.yaml

@@ -13,6 +13,9 @@
   - name: host-usr-lib
     hostPath:
       path: "/usr/lib"
+  - name: host-lib
+    hostPath:
+      path: "/lib"
   - name: source-d
     hostPath:
       path: "/etc/kubernetes/node-feature-discovery/source.d/"
@@ -38,6 +41,9 @@
   - name: host-usr-lib
     mountPath: "/host-usr/lib"
     readOnly: true
+  - name: host-lib
+    mountPath: "/host-lib"
+    readOnly: true
   - name: source-d
     mountPath: "/etc/kubernetes/node-feature-discovery/source.d/"
     readOnly: true

deployment/components/common/worker-mounts.yaml

@@ -13,6 +13,9 @@
   - name: host-usr-lib
     hostPath:
       path: "/usr/lib"
+  - name: host-lib
+    hostPath:
+      path: "/lib"
   - name: source-d
     hostPath:
       path: "/etc/kubernetes/node-feature-discovery/source.d/"
@@ -38,6 +41,9 @@
   - name: host-usr-lib
     mountPath: "/host-usr/lib"
     readOnly: true
+  - name: host-lib
+    mountPath: "/host-lib"
+    readOnly: true
   - name: source-d
     mountPath: "/etc/kubernetes/node-feature-discovery/source.d/"
     readOnly: true

deployment/helm/node-feature-discovery/templates/worker.yaml

@@ -67,6 +67,9 @@ spec:
         - name: host-usr-lib
           mountPath: "/host-usr/lib"
           readOnly: true
+        - name: host-lib
+          mountPath: "/host-lib"
+          readOnly: true
         {{- if .Values.worker.mountUsrSrc }}
         - name: host-usr-src
           mountPath: "/host-usr/src"
@@ -99,6 +102,9 @@ spec:
         - name: host-usr-lib
           hostPath:
             path: "/usr/lib"
+        - name: host-lib
+          hostPath:
+            path: "/lib"
         {{- if .Values.worker.mountUsrSrc }}
         - name: host-usr-src
           hostPath:

docs/usage/customization-guide.md

@@ -619,7 +619,8 @@ The following features are available for matching:
 | | |          **`nx_gzip`**                 | bool       | Nest Accelerator GZIP support is enabled
 | **`kernel.config`** | attribute |          |            | Kernel configuration options
 |                  |              | **`<config-flag>`** | string | Value of the kconfig option
-| **`kernel.loadedmodule`** | flag |         |            | Loaded kernel modules
+| **`kernel.loadedmodule`** | flag |         |            | Kernel modules loaded on the node as reported by `/proc/modules`
+| **`kernel.enabledmodule`** | flag |        |            | Kernel modules loaded on the node and available as built-ins as reported by `modules.builtin`
 |                  |              | **`mod-name`** |      | Kernel module `<mod-name>` is loaded
 | **`kernel.selinux`** | attribute |         |            | Kernel SELinux related features
 |                  |              | **`enabled`** | bool  | `true` if SELinux has been enabled and is in enforcing mode, otherwise `false`

pkg/utils/hostpath/hostpath.go

@@ -32,6 +32,8 @@ var (
 	UsrDir = HostDir(pathPrefix + "usr")
 	// VarDir is where the /var directory of the system to be inspected is located
 	VarDir = HostDir(pathPrefix + "var")
+	// LibDir is where the /lib directory of the system to be inspected is located
+	LibDir = HostDir(pathPrefix + "lib")
 )
 
 // HostDir is a helper for handling host system directories

source/kernel/kernel.go

@@ -30,10 +30,11 @@ import (
 const Name = "kernel"
 
 const (
-	ConfigFeature       = "config"
-	LoadedModuleFeature = "loadedmodule"
-	SelinuxFeature      = "selinux"
-	VersionFeature      = "version"
+	ConfigFeature        = "config"
+	LoadedModuleFeature  = "loadedmodule"
+	SelinuxFeature       = "selinux"
+	VersionFeature       = "version"
+	EnabledModuleFeature = "enabledmodule"
 )
 
 // Configuration file options
@@ -135,12 +136,21 @@ func (s *kernelSource) Discover() error {
 		s.legacyKconfig = legacyKconfig
 	}
 
+	var enabledModules []string
 	if kmods, err := getLoadedModules(); err != nil {
 		klog.Errorf("failed to get loaded kernel modules: %v", err)
 	} else {
+		enabledModules = append(enabledModules, kmods...)
 		s.features.Flags[LoadedModuleFeature] = nfdv1alpha1.NewFlagFeatures(kmods...)
 	}
 
+	if builtinMods, err := getBuiltinModules(); err != nil {
+		klog.Errorf("failed to get builtin kernel modules: %v", err)
+	} else {
+		enabledModules = append(enabledModules, builtinMods...)
+		s.features.Flags[EnabledModuleFeature] = nfdv1alpha1.NewFlagFeatures(enabledModules...)
+	}
+
 	if selinux, err := SelinuxEnabled(); err != nil {
 		klog.Warning(err)
 	} else {

source/kernel/modules.go

@@ -19,7 +19,10 @@ package kernel
 import (
 	"fmt"
 	"os"
+	"path"
 	"strings"
+
+	"sigs.k8s.io/node-feature-discovery/pkg/utils/hostpath"
 )
 
 const kmodProcfsPath = "/proc/modules"
@@ -31,7 +34,7 @@ func getLoadedModules() ([]string, error) {
 	}
 
 	lines := strings.Split(string(out), "\n")
-	loadedMods := make([]string, len(lines))
+	loadedMods := make([]string, 0, len(lines))
 	for _, line := range lines {
 		// skip empty lines
 		if len(line) == 0 {
@@ -42,3 +45,30 @@ func getLoadedModules() ([]string, error) {
 	}
 	return loadedMods, nil
 }
+
+func getBuiltinModules() ([]string, error) {
+	kVersion, err := getVersion()
+	if err != nil {
+		return []string{}, err
+	}
+
+	kBuiltinModPath := hostpath.LibDir.Path("modules/" + kVersion + "/modules.builtin")
+	out, err := os.ReadFile(kBuiltinModPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read file %s: %s", kBuiltinModPath, err.Error())
+	}
+
+	lines := strings.Split(string(out), "\n")
+	builtinMods := make([]string, 0, len(lines))
+	for _, line := range lines {
+		// skip empty lines
+		line = strings.TrimSpace(line)
+		if !strings.HasSuffix(line, ".ko") {
+			continue
+		}
+
+		// append loaded module
+		builtinMods = append(builtinMods, strings.TrimSuffix(path.Base(line), ".ko"))
+	}
+	return builtinMods, nil
+}