Fix Workflow Global Permissions Nil Check

signing/signing.go

@@ -222,7 +222,7 @@ func lookupPayload(ctx context.Context, payload []byte) (repoPath, repoRef, repo
 func verifyScorecardWorkflow(workflowContent string) error {
 	// Verify workflow contents using actionlint.
 	workflow, lintErrs := actionlint.Parse([]byte(workflowContent))
-	if lintErrs != nil {
+	if lintErrs != nil || workflow == nil {
 		return fmt.Errorf("actionlint errors parsing workflow: %v", lintErrs)
 	}
 
@@ -231,17 +231,18 @@ func verifyScorecardWorkflow(workflowContent string) error {
 		return errors.New("workflow contains global env vars or defaults")
 	}
 
-	// Verify that the all scope, if set, isn't write-all.
-	globalPermAll := workflow.Permissions.All
-	if globalPermAll != nil && globalPermAll.Value == "write-all" {
-		return fmt.Errorf("global perm is set to write-all")
-	}
+	if workflow.Permissions != nil {
+		globalPerms := workflow.Permissions
+		// Verify that the all scope, if set, isn't write-all.
+		if globalPerms.All != nil && globalPerms.All.Value == "write-all" {
+			return fmt.Errorf("global perm is set to write-all")
+		}
 
-	// Verify that there are no global permissions (including id-token) set to write.
-	globalPerms := workflow.Permissions.Scopes
-	for globalPerm, val := range globalPerms {
-		if val.Value.Value == "write" {
-			return fmt.Errorf("global perm %v is set to write", globalPerm)
+		// Verify that there are no global permissions (including id-token) set to write.
+		for globalPerm, val := range globalPerms.Scopes {
+			if val.Value.Value == "write" {
+				return fmt.Errorf("global perm %v is set to write", globalPerm)
+			}
 		}
 	}
 

signing/signing_test.go

@@ -46,10 +46,17 @@ func TestVerifySignatureInvalidRepo(t *testing.T) {
 	assert.Equal(t, http.StatusInternalServerError, w.Code)
 }
 
-func TestVerifyValidWorkflow(t *testing.T) {
-	workflowContent, _ := ioutil.ReadFile("../testdata/workflow-valid.yml")
-	err := verifyScorecardWorkflow(string(workflowContent))
-	assert.Equal(t, err, nil)
+func TestVerifyValidWorkflows(t *testing.T) {
+	workflowFiles := []string{
+		"../testdata/workflow-valid.yml",
+		"../testdata/workflow-valid-noglobalperm.yml",
+	}
+
+	for _, workflowFile := range workflowFiles {
+		workflowContent, _ := ioutil.ReadFile(workflowFile)
+		err := verifyScorecardWorkflow(string(workflowContent))
+		assert.Equal(t, err, nil, workflowFile)
+	}
 }
 
 func TestVerifyInvalidWorkflows(t *testing.T) {

testdata/workflow-valid-noglobalperm.yml

@@ -0,0 +1,56 @@
+name: Scorecards supply-chain security
+on: 
+  # Only the default branch is supported.
+  branch_protection_rule:
+  schedule:
+    # Weekly on Saturdays.
+    - cron: '30 1 * * 6'
+  push:
+    branches: [ $default-branch ]
+  workflow_dispatch:
+
+jobs:
+  analysis:
+    name: Scorecards analysis
+    runs-on: ubuntu-latest
+    permissions:
+      # Needed to upload the results to code-scanning dashboard.
+      security-events: write
+      actions: read
+      contents: read
+      id-token: write # needed for keyless signing
+
+    steps:
+      - name: "Checkout code"
+        uses: actions/checkout@ec3a7ce113134d7a93b817d10a8272cb61118579 # v2.4.0
+        with:
+          persist-credentials: false
+
+      - name: "Run analysis"
+        uses: ossf/scorecard-action@c8416b0b2bf627c349ca92fc8e3de51a64b005cf # v1.0.2
+        with:
+          results_file: results.sarif
+          results_format: sarif
+          # Read-only PAT token. To create it,
+          # follow the steps in https://github.com/ossf/scorecard-action#pat-token-creation.
+          repo_token: ${{ secrets.SCORECARD_READ_TOKEN }}
+          # Publish the results for public repositories to enable scorecard badges. For more details, see
+          # https://github.com/ossf/scorecard-action#publishing-results. 
+          # For private repositories, `publish_results` will automatically be set to `false`, regardless 
+          # of the value entered here.
+          publish_results: true
+
+      # Upload the results as artifacts (optional). Commenting out will disable uploads of run results in SARIF
+      # format to the repository Actions tab.
+      - name: "Upload artifact"
+        uses: actions/upload-artifact@82c141cc518b40d92cc801eee768e7aafc9c2fa2 # v2.3.1
+        with:
+          name: SARIF file
+          path: results.sarif
+          retention-days: 5
+
+      # Upload the results to GitHub's code scanning dashboard.
+      - name: "Upload to code-scanning"
+        uses: github/codeql-action/upload-sarif@5f532563584d71fdef14ee64d17bafb34f751ce5 # v1.0.26
+        with:
+          sarif_file: results.sarif