fix(helm): scan the subcharts once (aquasecurity#6382)

pkg/iac/scanners/helm/scanner.go

@@ -7,6 +7,7 @@ import (
 	"io/fs"
 	"path/filepath"
 	"strings"
+	"sync"
 
 	"github.com/liamg/memoryfs"
 
@@ -38,6 +39,8 @@ type Scanner struct {
 	skipRequired          bool
 	frameworks            []framework.Framework
 	spec                  string
+	regoScanner           *rego.Scanner
+	mu                    sync.Mutex
 }
 
 func (s *Scanner) SetSpec(spec string) {
@@ -120,6 +123,10 @@ func (s *Scanner) SetRegoErrorLimit(_ int)   {}
 
 func (s *Scanner) ScanFS(ctx context.Context, target fs.FS, path string) (scan.Results, error) {
 
+	if err := s.initRegoScanner(target); err != nil {
+		return nil, fmt.Errorf("failed to init rego scanner: %w", err)
+	}
+
 	var results []scan.Result
 	if err := fs.WalkDir(target, path, func(path string, d fs.DirEntry, err error) error {
 		select {
@@ -150,6 +157,7 @@ func (s *Scanner) ScanFS(ctx context.Context, target fs.FS, path string) (scan.R
 			} else {
 				results = append(results, scanResults...)
 			}
+			return fs.SkipDir
 		}
 
 		return nil
@@ -174,14 +182,6 @@ func (s *Scanner) getScanResults(path string, ctx context.Context, target fs.FS)
 		return nil, nil
 	}
 
-	regoScanner := rego.NewScanner(types.SourceKubernetes, s.options...)
-	policyFS := target
-	if s.policyFS != nil {
-		policyFS = s.policyFS
-	}
-	if err := regoScanner.LoadPolicies(s.loadEmbeddedLibraries, s.loadEmbeddedPolicies, policyFS, s.policyDirs, s.policyReaders); err != nil {
-		return nil, fmt.Errorf("policies load: %w", err)
-	}
 	for _, file := range chartFiles {
 		file := file
 		s.debug.Log("Processing rendered chart file: %s", file.TemplateFilePath)
@@ -191,7 +191,7 @@ func (s *Scanner) getScanResults(path string, ctx context.Context, target fs.FS)
 			return nil, fmt.Errorf("unmarshal yaml: %w", err)
 		}
 		for _, manifest := range manifests {
-			fileResults, err := regoScanner.ScanInput(ctx, rego.Input{
+			fileResults, err := s.regoScanner.ScanInput(ctx, rego.Input{
 				Path:     file.TemplateFilePath,
 				Contents: manifest,
 				FS:       target,
@@ -219,3 +219,18 @@ func (s *Scanner) getScanResults(path string, ctx context.Context, target fs.FS)
 	}
 	return results, nil
 }
+
+func (s *Scanner) initRegoScanner(srcFS fs.FS) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.regoScanner != nil {
+		return nil
+	}
+	regoScanner := rego.NewScanner(types.SourceKubernetes, s.options...)
+	regoScanner.SetParentDebugLogger(s.debug)
+	if err := regoScanner.LoadPolicies(s.loadEmbeddedLibraries, s.loadEmbeddedPolicies, srcFS, s.policyDirs, s.policyReaders); err != nil {
+		return err
+	}
+	s.regoScanner = regoScanner
+	return nil
+}

pkg/iac/scanners/helm/test/scanner_test.go

@@ -318,3 +318,44 @@ deny[res] {
 	require.NoError(t, err)
 	assert.NotNil(t, code)
 }
+
+func TestScanSubchartOnce(t *testing.T) {
+	check := `# METADATA
+# title: "Test rego"
+# description: "Test rego"
+# scope: package
+# schemas:
+# - input: schema["kubernetes"]
+# custom:
+#   id: ID001
+#   avd_id: AVD-USR-ID001
+#   severity: LOW
+#   input:
+#     selector:
+#     - type: kubernetes
+#       subtypes:
+#         - kind: pod
+package user.kubernetes.ID001
+
+import data.lib.kubernetes
+
+deny[res] {
+	container := kubernetes.containers[_]
+	container.securityContext.readOnlyRootFilesystem == false
+	res := result.new("set 'securityContext.readOnlyRootFilesystem' to true", container)
+}
+`
+
+	scanner := helm.New(
+		options.ScannerWithEmbeddedPolicies(false),
+		options.ScannerWithEmbeddedLibraries(true),
+		options.ScannerWithPolicyNamespaces("user"),
+		options.ScannerWithPolicyReader(strings.NewReader(check)),
+	)
+
+	results, err := scanner.ScanFS(context.TODO(), os.DirFS("testdata/with-subchart"), ".")
+	require.NoError(t, err)
+	require.Len(t, results, 1)
+
+	assert.Len(t, results.GetFailed(), 0)
+}

pkg/iac/scanners/helm/test/testdata/with-subchart/Chart.yaml

@@ -0,0 +1,6 @@
+apiVersion: v2
+name: test
+description: A Helm chart for Kubernetes
+type: application
+version: 0.1.0
+appVersion: "1.16.0"

pkg/iac/scanners/helm/test/testdata/with-subchart/charts/nginx/Chart.yaml

@@ -0,0 +1,6 @@
+apiVersion: v2
+name: nginx
+description: A Helm chart for Kubernetes
+type: application
+version: 0.1.0
+appVersion: "1.16.0"

pkg/iac/scanners/helm/test/testdata/with-subchart/charts/nginx/templates/pod.yaml

@@ -0,0 +1,12 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: nginx
+spec:
+  containers:
+  - name: nginx
+    image: nginx:1.14.2
+    ports:
+    - containerPort: 8080
+    securityContext:
+      readOnlyRootFilesystem: {{ .Values.readOnlyFs }}

pkg/iac/scanners/helm/test/testdata/with-subchart/charts/nginx/values.yaml

@@ -0,0 +1 @@
+readOnlyFs: false

pkg/iac/scanners/helm/test/testdata/with-subchart/values.yaml

@@ -0,0 +1,2 @@
+nginx:
+  readOnlyFs: true