bug: always use the default GITHUB_TOKEN for signing (#898)

* update

* update

* update

* update

* update

* update

.golangci.yml

@@ -56,7 +56,6 @@ linters:
     - misspell
     - nakedret
     - nestif
-    - noctx
     - nolintlint
     - paralleltest
     - predeclared

github/github.go

@@ -91,6 +91,7 @@ func (c *Client) ParseFromURL(baseRepoURL, repoName string) (RepoInfo, error) {
 	}
 
 	log.Printf("getting repo info from URL: %s", repoURL.String())
+	//nolint:noctx
 	req, err := http.NewRequestWithContext(
 		c.ctx,
 		http.MethodGet,

main.go

@@ -41,15 +41,20 @@ func main() {
 		}
 
 		// Sign json results.
-		if err = signing.SignScorecardResult("results.json"); err != nil {
+		// Always use the default GitHub token, never a PAT.
+		accessToken := os.Getenv(options.EnvInputInternalRepoToken)
+		s, err := signing.New(accessToken)
+		if err != nil {
+			log.Fatalf("error SigningNew: %v", err)
+		}
+		if err = s.SignScorecardResult("results.json"); err != nil {
 			log.Fatalf("error signing scorecard json results: %v", err)
 		}
 
 		// Processes json results.
 		repoName := os.Getenv(options.EnvGithubRepository)
 		repoRef := os.Getenv(options.EnvGithubRef)
-		accessToken := os.Getenv(options.EnvInputRepoToken)
-		if err := signing.ProcessSignature(jsonPayload, repoName, repoRef, accessToken); err != nil {
+		if err := s.ProcessSignature(jsonPayload, repoName, repoRef); err != nil {
 			log.Fatalf("error processing signature: %v", err)
 		}
 	}

signing/signing.go

@@ -20,11 +20,13 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"net/url"
 	"os"
+	"strings"
 	"time"
 
 	sigOpts "github.com/sigstore/cosign/cmd/cosign/cli/options"
@@ -34,15 +36,45 @@ import (
 	"github.com/ossf/scorecard-action/options"
 )
 
-// SignScorecardResult signs the results file and uploads the attestation to the Rekor transparency log.
-func SignScorecardResult(scorecardResultsFile string) error {
+var (
+	errorEmptyToken   = errors.New("error token empty")
+	errorInvalidToken = errors.New("invalid token")
+)
+
+// Signing is a signing structure.
+type Signing struct {
+	token string
+}
+
+// New creates a new Signing instance.
+func New(token string) (*Signing, error) {
+	// Set the default GITHUB_TOKEN, because it's not available by default
+	// in a GitHub Action. We need it for OIDC.
+	if token == "" {
+		return nil, fmt.Errorf("%w", errorEmptyToken)
+	}
+
+	// Check for a workflow secret.
+	if !strings.HasPrefix(token, "ghs_") {
+		return nil, fmt.Errorf("%w: not a default GITHUB_TOKEN", errorInvalidToken)
+	}
+	if err := os.Setenv("GITHUB_TOKEN", token); err != nil {
+		return nil, fmt.Errorf("error setting GITHUB_TOKEN env var: %w", err)
+	}
+
 	if err := os.Setenv("COSIGN_EXPERIMENTAL", "true"); err != nil {
-		return fmt.Errorf("error setting COSIGN_EXPERIMENTAL env var: %w", err)
+		return nil, fmt.Errorf("error setting COSIGN_EXPERIMENTAL env var: %w", err)
 	}
 
+	return &Signing{
+		token: token,
+	}, nil
+}
+
+// SignScorecardResult signs the results file and uploads the attestation to the Rekor transparency log.
+func (s *Signing) SignScorecardResult(scorecardResultsFile string) error {
 	// Prepare settings for SignBlobCmd.
 	rootOpts := &sigOpts.RootOptions{Timeout: sigOpts.DefaultTimeout} // Just the timeout.
-
 	keyOpts := sigOpts.KeyOpts{
 		FulcioURL:    sigOpts.DefaultFulcioURL,     // Signing certificate provider.
 		RekorURL:     sigOpts.DefaultRekorURL,      // Transparency log.
@@ -87,7 +119,7 @@ func GetJSONScorecardResults() ([]byte, error) {
 }
 
 // ProcessSignature calls scorecard-api to process & upload signed scorecard results.
-func ProcessSignature(jsonPayload []byte, repoName, repoRef, accessToken string) error {
+func (s *Signing) ProcessSignature(jsonPayload []byte, repoName, repoRef string) error {
 	// Prepare HTTP request body for scorecard-webapp-api call.
 	// TODO: Use the `ScorecardResult` struct from `scorecard-webapp`.
 	resultsPayload := struct {
@@ -97,7 +129,7 @@ func ProcessSignature(jsonPayload []byte, repoName, repoRef, accessToken string)
 	}{
 		Result:      string(jsonPayload),
 		Branch:      repoRef,
-		AccessToken: accessToken,
+		AccessToken: s.token,
 	}
 
 	payloadBytes, err := json.Marshal(resultsPayload)
@@ -113,7 +145,7 @@ func ProcessSignature(jsonPayload []byte, repoName, repoRef, accessToken string)
 	if err != nil {
 		return fmt.Errorf("parsing Scorecard API endpoint: %w", err)
 	}
-	req, err := http.NewRequest("POST", parsedURL.String(), bytes.NewBuffer(payloadBytes)) //nolint
+	req, err := http.NewRequest("POST", parsedURL.String(), bytes.NewBuffer(payloadBytes))
 	if err != nil {
 		return fmt.Errorf("creating HTTP request: %w", err)
 	}

signing/signing_test.go

@@ -17,6 +17,7 @@
 package signing
 
 import (
+	"fmt"
 	"os"
 	"testing"
 
@@ -88,7 +89,11 @@ func Test_ProcessSignature(t *testing.T) {
 		t.Errorf("Error reading testdata:, %v", err)
 	}
 
-	if err := ProcessSignature(jsonPayload, repoName, repoRef, accessToken); err != nil {
+	s, err := New(accessToken)
+	if err != nil {
+		panic(fmt.Sprintf("error SigningNew: %v", err))
+	}
+	if err := s.ProcessSignature(jsonPayload, repoName, repoRef); err != nil {
 		t.Errorf("ProcessSignature() error:, %v", err)
 		return
 	}