Merge pull request #23 from fluxcd/signature-verification

gitrepository: Implement PGP signature verification

Author: stefanprodan

api/v1alpha1/condition_types.go

@@ -65,4 +65,8 @@ const (
 	// AuthenticationFailedReason represents the fact that a given secret does not
 	// have the required fields or the provided credentials do not match.
 	AuthenticationFailedReason string = "AuthenticationFailed"
+
+	// VerificationFailedReason represents the fact that the cryptographic provenance
+	// verification for the source failed.
+	VerificationFailedReason string = "VerificationFailed"
 )

api/v1alpha1/gitrepository_types.go

@@ -44,6 +44,10 @@ type GitRepositorySpec struct {
 	// master branch.
 	// +optional
 	Reference *GitRepositoryRef `json:"ref,omitempty"`
+
+	// Verify OpenPGP signature for the commit that HEAD points to.
+	// +optional
+	Verification *GitRepositoryVerification `json:"verify,omitempty"`
 }
 
 // GitRepositoryRef defines the git ref used for pull and checkout operations.
@@ -66,7 +70,17 @@ type GitRepositoryRef struct {
 	Commit string `json:"commit"`
 }
 
-// GitRepositoryStatus defines the observed state of the GitRepository.
+// GitRepositoryVerification defines the OpenPGP signature verification process.
+type GitRepositoryVerification struct {
+	// Mode describes what git object should be verified, currently ('head').
+	// +kubebuilder:validation:Enum=head
+	Mode string `json:"mode"`
+
+	// The secret name containing the public keys of all trusted git authors.
+	SecretRef corev1.LocalObjectReference `json:"secretRef,omitempty"`
+}
+
+// GitRepositoryStatus defines the observed state of a Git repository.
 type GitRepositoryStatus struct {
 	// +optional
 	Conditions []SourceCondition `json:"conditions,omitempty"`

api/v1alpha1/zz_generated.deepcopy.go

@@ -86,12 +86,34 @@ spec:
               description: The repository URL, can be a HTTP or SSH address.
               pattern: ^(http|https|ssh)://
               type: string
+            verify:
+              description: Verify OpenPGP signature for the commit that HEAD points
+                to.
+              properties:
+                mode:
+                  description: Mode describes what git object should be verified,
+                    currently ('head').
+                  enum:
+                  - head
+                  type: string
+                secretRef:
+                  description: The secret name containing the public keys of all trusted
+                    git authors.
+                  properties:
+                    name:
+                      description: 'Name of the referent. More info: https://kubernetes.io/docs/concepts/overview/working-with-objects/names/#names
+                        TODO: Add other useful fields. apiVersion, kind, uid?'
+                      type: string
+                  type: object
+              required:
+              - mode
+              type: object
           required:
           - interval
           - url
           type: object
         status:
-          description: GitRepositoryStatus defines the observed state of the GitRepository.
+          description: GitRepositoryStatus defines the observed state of a Git repository.
           properties:
             artifact:
               description: Artifact represents the output of the last successful repository

config/crd/bases/source.fluxcd.io_gitrepositories.yaml

@@ -36,7 +36,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	sourcev1 "github.com/fluxcd/source-controller/api/v1alpha1"
-	internalgit "github.com/fluxcd/source-controller/internal/git"
+	intgit "github.com/fluxcd/source-controller/internal/git"
 )
 
 // GitRepositoryReconciler reconciles a GitRepository object
@@ -76,10 +76,11 @@ func (r *GitRepositoryReconciler) Reconcile(req ctrl.Request) (ctrl.Result, erro
 		log.Error(err, "artifacts GC failed")
 	}
 
-	// try git clone
+	// try git sync
 	syncedRepo, err := r.sync(ctx, *repo.DeepCopy())
 	if err != nil {
 		log.Error(err, "Git repository sync failed")
+		return ctrl.Result{Requeue: true}, err
 	}
 
 	// update status
@@ -128,6 +129,7 @@ func (r *GitRepositoryReconciler) sync(ctx context.Context, repository sourcev1.
 		}
 	}
 
+	// determine auth method
 	var auth transport.AuthMethod
 	if repository.Spec.SecretRef != nil {
 		name := types.NamespacedName{
@@ -142,7 +144,7 @@ func (r *GitRepositoryReconciler) sync(ctx context.Context, repository sourcev1.
 			return sourcev1.GitRepositoryNotReady(repository, sourcev1.AuthenticationFailedReason, err.Error()), err
 		}
 
-		method, cleanup, err := internalgit.AuthMethodFromSecret(repository.Spec.URL, secret)
+		method, cleanup, err := intgit.AuthMethodFromSecret(repository.Spec.URL, secret)
 		if err != nil {
 			err = fmt.Errorf("auth error: %w", err)
 			return sourcev1.GitRepositoryNotReady(repository, sourcev1.AuthenticationFailedReason, err.Error()), err
@@ -259,6 +261,45 @@ func (r *GitRepositoryReconciler) sync(ctx context.Context, repository sourcev1.
 		return sourcev1.GitRepositoryNotReady(repository, sourcev1.GitOperationFailedReason, err.Error()), err
 	}
 
+	// verify PGP signature
+	if repository.Spec.Verification != nil {
+		commit, err := repo.CommitObject(ref.Hash())
+		if err != nil {
+			err = fmt.Errorf("git resolve HEAD error: %w", err)
+			return sourcev1.GitRepositoryNotReady(repository, sourcev1.GitOperationFailedReason, err.Error()), err
+		}
+
+		if commit.PGPSignature == "" {
+			err = fmt.Errorf("PGP signature not found for commit '%s'", ref.Hash())
+			return sourcev1.GitRepositoryNotReady(repository, sourcev1.VerificationFailedReason, err.Error()), err
+		}
+
+		name := types.NamespacedName{
+			Namespace: repository.GetNamespace(),
+			Name:      repository.Spec.Verification.SecretRef.Name,
+		}
+
+		var secret corev1.Secret
+		err = r.Client.Get(ctx, name, &secret)
+		if err != nil {
+			err = fmt.Errorf("PGP public keys secret error: %w", err)
+			return sourcev1.GitRepositoryNotReady(repository, sourcev1.VerificationFailedReason, err.Error()), err
+		}
+
+		var verified bool
+		for _, bytes := range secret.Data {
+			if _, err := commit.Verify(string(bytes)); err == nil {
+				verified = true
+				break
+			}
+		}
+
+		if !verified {
+			err = fmt.Errorf("PGP signature of '%s' can't be verified", commit.Author)
+			return sourcev1.GitRepositoryNotReady(repository, sourcev1.VerificationFailedReason, err.Error()), err
+		}
+	}
+
 	if revision == "" {
 		revision = fmt.Sprintf("%s/%s", branch, ref.Hash().String())
 	}
@@ -307,7 +348,6 @@ func (r *GitRepositoryReconciler) shouldResetStatus(repository sourcev1.GitRepos
 		}
 	}
 
-	// set initial status
 	if len(repository.Status.Conditions) == 0 || resetStatus {
 		resetStatus = true
 	}