Accept a slice of remote.Option for cosign verification

If implemented this enable passing a keychain, an authenticator and a
custom transport as remote.Option to the verifier. It enables contextual
login, self-signed certificates and insecure registries.

Signed-off-by: Soule BA <soule@weave.works>

Author: souleb

controllers/ocirepository_controller.go

@@ -297,6 +297,8 @@ func (r *OCIRepositoryReconciler) reconcile(ctx context.Context, obj *sourcev1.O
 // reconcileSource fetches the upstream OCI artifact metadata and content.
 // If this fails, it records v1beta2.FetchFailedCondition=True on the object and returns early.
 func (r *OCIRepositoryReconciler) reconcileSource(ctx context.Context, obj *sourcev1.OCIRepository, metadata *sourcev1.Artifact, dir string) (sreconcile.Result, error) {
+	var auth authn.Authenticator
+
 	ctxTimeout, cancel := context.WithTimeout(ctx, obj.Spec.Timeout.Duration)
 	defer cancel()
 
@@ -308,8 +310,6 @@ func (r *OCIRepositoryReconciler) reconcileSource(ctx context.Context, obj *sour
 		conditions.Delete(obj, sourcev1.SourceVerifiedCondition)
 	}
 
-	options := r.craneOptions(ctxTimeout, obj.Spec.Insecure)
-
 	// Generate the registry credential keychain either from static credentials or using cloud OIDC
 	keychain, err := r.keychain(ctx, obj)
 	if err != nil {
@@ -320,10 +320,10 @@ func (r *OCIRepositoryReconciler) reconcileSource(ctx context.Context, obj *sour
 		conditions.MarkTrue(obj, sourcev1.FetchFailedCondition, e.Reason, e.Err.Error())
 		return sreconcile.ResultEmpty, e
 	}
-	options = append(options, crane.WithAuthFromKeychain(keychain))
 
 	if _, ok := keychain.(soci.Anonymous); obj.Spec.Provider != sourcev1.GenericOCIProvider && ok {
-		auth, authErr := oidcAuth(ctxTimeout, obj.Spec.URL, obj.Spec.Provider)
+		var authErr error
+		auth, authErr = oidcAuth(ctxTimeout, obj.Spec.URL, obj.Spec.Provider)
 		if authErr != nil && !errors.Is(authErr, oci.ErrUnconfiguredProvider) {
 			e := serror.NewGeneric(
 				fmt.Errorf("failed to get credential from %s: %w", obj.Spec.Provider, authErr),
@@ -332,9 +332,6 @@ func (r *OCIRepositoryReconciler) reconcileSource(ctx context.Context, obj *sour
 			conditions.MarkTrue(obj, sourcev1.FetchFailedCondition, e.Reason, e.Err.Error())
 			return sreconcile.ResultEmpty, e
 		}
-		if auth != nil {
-			options = append(options, crane.WithAuth(auth))
-		}
 	}
 
 	// Generate the transport for remote operations
@@ -347,12 +344,11 @@ func (r *OCIRepositoryReconciler) reconcileSource(ctx context.Context, obj *sour
 		conditions.MarkTrue(obj, sourcev1.FetchFailedCondition, e.Reason, e.Err.Error())
 		return sreconcile.ResultEmpty, e
 	}
-	if transport != nil {
-		options = append(options, crane.WithTransport(transport))
-	}
+
+	opts := r.makeOptions(ctx, obj, withTransport(transport), withKeychainOrAuth(keychain, auth))
 
 	// Determine which artifact revision to pull
-	url, err := r.getArtifactURL(obj, options)
+	url, err := r.getArtifactURL(obj, opts.craneOpts)
 	if err != nil {
 		if _, ok := err.(invalidOCIURLError); ok {
 			e := serror.NewStalling(
@@ -370,7 +366,7 @@ func (r *OCIRepositoryReconciler) reconcileSource(ctx context.Context, obj *sour
 	}
 
 	// Get the upstream revision from the artifact digest
-	revision, err := r.getRevision(url, options)
+	revision, err := r.getRevision(url, opts.craneOpts)
 	if err != nil {
 		e := serror.NewGeneric(
 			fmt.Errorf("failed to determine artifact digest: %w", err),
@@ -401,7 +397,7 @@ func (r *OCIRepositoryReconciler) reconcileSource(ctx context.Context, obj *sour
 	} else if !obj.GetArtifact().HasRevision(revision) ||
 		conditions.GetObservedGeneration(obj, sourcev1.SourceVerifiedCondition) != obj.Generation ||
 		conditions.IsFalse(obj, sourcev1.SourceVerifiedCondition) {
-		err := r.verifySignature(ctx, obj, url, keychain)
+		err := r.verifySignature(ctx, obj, url, opts.verifyOpts...)
 		if err != nil {
 			provider := obj.Spec.Verify.Provider
 			if obj.Spec.Verify.SecretRef == nil {
@@ -425,7 +421,7 @@ func (r *OCIRepositoryReconciler) reconcileSource(ctx context.Context, obj *sour
 	}
 
 	// Pull artifact from the remote container registry
-	img, err := crane.Pull(url, options...)
+	img, err := crane.Pull(url, opts.craneOpts...)
 	if err != nil {
 		e := serror.NewGeneric(
 			fmt.Errorf("failed to pull artifact from '%s': %w", obj.Spec.URL, err),
@@ -585,15 +581,15 @@ func (r *OCIRepositoryReconciler) digestFromRevision(revision string) string {
 
 // verifySignature verifies the authenticity of the given image reference url. First, it tries using a key
 // if a secret with a valid public key is provided. If not, it falls back to a keyless approach for verification.
-func (r *OCIRepositoryReconciler) verifySignature(ctx context.Context, obj *sourcev1.OCIRepository, url string, keychain authn.Keychain) error {
+func (r *OCIRepositoryReconciler) verifySignature(ctx context.Context, obj *sourcev1.OCIRepository, url string, opt ...remote.Option) error {
 	ctxTimeout, cancel := context.WithTimeout(ctx, obj.Spec.Timeout.Duration)
 	defer cancel()
 
 	provider := obj.Spec.Verify.Provider
 	switch provider {
 	case "cosign":
 		defaultCosignOciOpts := []soci.Options{
-			soci.WithAuthnKeychain(keychain),
+			soci.WithRemoteOptions(opt...),
 		}
 
 		ref, err := name.ParseReference(url)
@@ -1125,3 +1121,46 @@ func (r *OCIRepositoryReconciler) notify(ctx context.Context, oldObj, newObj *so
 		}
 	}
 }
+
+func (r *OCIRepositoryReconciler) makeOptions(ctxTimeout context.Context, obj *sourcev1.OCIRepository, opts ...Option) remoteOptions {
+	o := remoteOptions{
+		craneOpts:  r.craneOptions(ctxTimeout, obj.Spec.Insecure),
+		verifyOpts: []remote.Option{},
+	}
+
+	for _, opt := range opts {
+		opt(&o)
+	}
+
+	return o
+}
+
+type remoteOptions struct {
+	craneOpts  []crane.Option
+	verifyOpts []remote.Option
+}
+
+type Option func(*remoteOptions)
+
+func withKeychainOrAuth(keychain authn.Keychain, auth authn.Authenticator) Option {
+	return func(o *remoteOptions) {
+		if auth != nil {
+			// auth take precedence over keychain here as we expect the caller to set
+			// the auth only if it is required.
+			o.verifyOpts = append(o.verifyOpts, remote.WithAuth(auth))
+			o.craneOpts = append(o.craneOpts, crane.WithAuth(auth))
+		} else {
+			o.verifyOpts = append(o.verifyOpts, remote.WithAuthFromKeychain(keychain))
+			o.craneOpts = append(o.craneOpts, crane.WithAuthFromKeychain(keychain))
+		}
+	}
+}
+
+func withTransport(transport http.RoundTripper) Option {
+	return func(o *remoteOptions) {
+		if transport != nil {
+			o.craneOpts = append(o.craneOpts, crane.WithTransport(transport))
+			o.verifyOpts = append(o.verifyOpts, remote.WithTransport(transport))
+		}
+	}
+}

internal/oci/verifier.go

@@ -20,7 +20,7 @@ import (
 	"context"
 	"crypto"
 	"fmt"
-	"github.com/google/go-containerregistry/pkg/authn"
+
 	"github.com/google/go-containerregistry/pkg/v1/remote"
 	"github.com/sigstore/cosign/cmd/cosign/cli/fulcio"
 	"github.com/sigstore/cosign/cmd/cosign/cli/rekor"
@@ -37,7 +37,7 @@ import (
 // options is a struct that holds options for verifier.
 type options struct {
 	PublicKey []byte
-	Keychain  authn.Keychain
+	ROpt      []remote.Option
 }
 
 // Options is a function that configures the options applied to a Verifier.
@@ -50,9 +50,11 @@ func WithPublicKey(publicKey []byte) Options {
 	}
 }
 
-func WithAuthnKeychain(keychain authn.Keychain) Options {
-	return func(opts *options) {
-		opts.Keychain = keychain
+// WithRemoteOptions is a functional option for overriding the default
+// remote options used by the verifier.
+func WithRemoteOptions(opts ...remote.Option) Options {
+	return func(o *options) {
+		o.ROpt = opts
 	}
 }
 
@@ -76,8 +78,8 @@ func NewVerifier(ctx context.Context, opts ...Options) (*Verifier, error) {
 		return nil, err
 	}
 
-	if o.Keychain != nil {
-		co = append(co, ociremote.WithRemoteOptions(remote.WithAuthFromKeychain(o.Keychain)))
+	if o.ROpt != nil {
+		co = append(co, ociremote.WithRemoteOptions(o.ROpt...))
 	}
 
 	checkOpts.RegistryClientOpts = co

internal/oci/verifier_test.go

@@ -0,0 +1,105 @@
+/*
+Copyright 2022 The Flux authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package oci
+
+import (
+	"net/http"
+	"reflect"
+	"testing"
+
+	"github.com/google/go-containerregistry/pkg/authn"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+func TestOptions(t *testing.T) {
+	tests := []struct {
+		name string
+		opts []Options
+		want *options
+	}{{
+		name: "no options",
+		want: &options{},
+	}, {
+		name: "signature option",
+		opts: []Options{WithPublicKey([]byte("foo"))},
+		want: &options{
+			PublicKey: []byte("foo"),
+			ROpt:      nil,
+		},
+	}, {
+		name: "keychain option",
+		opts: []Options{WithRemoteOptions(remote.WithAuthFromKeychain(authn.DefaultKeychain))},
+		want: &options{
+			PublicKey: nil,
+			ROpt:      []remote.Option{remote.WithAuthFromKeychain(authn.DefaultKeychain)},
+		},
+	}, {
+		name: "keychain and authenticator option",
+		opts: []Options{WithRemoteOptions(
+			remote.WithAuth(&authn.Basic{Username: "foo", Password: "bar"}),
+			remote.WithAuthFromKeychain(authn.DefaultKeychain),
+		)},
+		want: &options{
+			PublicKey: nil,
+			ROpt: []remote.Option{
+				remote.WithAuth(&authn.Basic{Username: "foo", Password: "bar"}),
+				remote.WithAuthFromKeychain(authn.DefaultKeychain),
+			},
+		},
+	}, {
+		name: "keychain, authenticator and transport option",
+		opts: []Options{WithRemoteOptions(
+			remote.WithAuth(&authn.Basic{Username: "foo", Password: "bar"}),
+			remote.WithAuthFromKeychain(authn.DefaultKeychain),
+			remote.WithTransport(http.DefaultTransport),
+		)},
+		want: &options{
+			PublicKey: nil,
+			ROpt: []remote.Option{
+				remote.WithAuth(&authn.Basic{Username: "foo", Password: "bar"}),
+				remote.WithAuthFromKeychain(authn.DefaultKeychain),
+				remote.WithTransport(http.DefaultTransport),
+			},
+		},
+	},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			o := options{}
+			for _, opt := range test.opts {
+				opt(&o)
+			}
+			if !reflect.DeepEqual(o.PublicKey, test.want.PublicKey) {
+				t.Errorf("got %#v, want %#v", &o.PublicKey, test.want.PublicKey)
+			}
+
+			if test.want.ROpt != nil {
+				if len(o.ROpt) != len(test.want.ROpt) {
+					t.Errorf("got %d remote options, want %d", len(o.ROpt), len(test.want.ROpt))
+				}
+				return
+			}
+
+			if test.want.ROpt == nil {
+				if len(o.ROpt) != 0 {
+					t.Errorf("got %d remote options, want %d", len(o.ROpt), 0)
+				}
+			}
+		})
+	}
+}