JWTAuthenticator distributed claims resolution honors tls config

Kube 1.23 introduced a new field on the OIDC Authenticator which
allows us to pass in a client with our own TLS config. See
https://github.com/kubernetes/kubernetes/pull/106141.

Signed-off-by: Margo Crawford <margaretc@vmware.com>

internal/controller/authenticator/jwtcachefiller/jwtcachefiller.go

@@ -1,4 +1,4 @@
-// Copyright 2020-2021 the Pinniped contributors. All Rights Reserved.
+// Copyright 2020-2022 the Pinniped contributors. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
 // Package jwtcachefiller implements a controller for filling an authncache.Cache with each
@@ -17,7 +17,6 @@ import (
 	"gopkg.in/square/go-jose.v2"
 	"k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apiserver/pkg/authentication/authenticator"
-	"k8s.io/apiserver/pkg/server/dynamiccertificates"
 	"k8s.io/apiserver/plugin/pkg/authenticator/token/oidc"
 	"k8s.io/klog/v2"
 
@@ -150,19 +149,11 @@ func (c *controller) extractValueAsJWTAuthenticator(value authncache.Value) *jwt
 
 // newJWTAuthenticator creates a jwt authenticator from the provided spec.
 func newJWTAuthenticator(spec *auth1alpha1.JWTAuthenticatorSpec) (*jwtAuthenticator, error) {
-	rootCAs, caBundle, err := pinnipedauthenticator.CABundle(spec.TLS)
+	rootCAs, _, err := pinnipedauthenticator.CABundle(spec.TLS)
 	if err != nil {
 		return nil, fmt.Errorf("invalid TLS configuration: %w", err)
 	}
 
-	var caContentProvider oidc.CAContentProvider
-	if len(caBundle) != 0 {
-		var caContentProviderErr error
-		caContentProvider, caContentProviderErr = dynamiccertificates.NewStaticCAContent("ignored", caBundle)
-		if caContentProviderErr != nil {
-			return nil, caContentProviderErr // impossible since caBundle is validated already
-		}
-	}
 	usernameClaim := spec.Claims.Username
 	if usernameClaim == "" {
 		usernameClaim = defaultUsernameClaim
@@ -199,7 +190,6 @@ func newJWTAuthenticator(spec *auth1alpha1.JWTAuthenticatorSpec) (*jwtAuthentica
 	if len(providerJSON.JWKSURL) == 0 {
 		return nil, fmt.Errorf("issuer %q does not have jwks_uri set", spec.Issuer)
 	}
-
 	oidcAuthenticator, err := oidc.New(oidc.Options{
 		IssuerURL:            spec.Issuer,
 		KeySet:               coreosoidc.NewRemoteKeySet(ctx, providerJSON.JWKSURL),
@@ -207,9 +197,7 @@ func newJWTAuthenticator(spec *auth1alpha1.JWTAuthenticatorSpec) (*jwtAuthentica
 		UsernameClaim:        usernameClaim,
 		GroupsClaim:          groupsClaim,
 		SupportedSigningAlgs: defaultSupportedSigningAlgos(),
-		// this is still needed for distributed claim resolution, meaning this uses a http client that does not honor our TLS config
+		Client:               client,
-		// TODO fix when we pick up https://github.com/kubernetes/kubernetes/pull/106141
-		CAContentProvider: caContentProvider,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("could not initialize authenticator: %w", err)

internal/controller/authenticator/jwtcachefiller/jwtcachefiller_test.go

@@ -58,6 +58,9 @@ func TestController(t *testing.T) {
 	require.NoError(t, err)
 	goodRSASigningAlgo := jose.RS256
 
+	customGroupsClaim := "my-custom-groups-claim"
+	distributedGroups := []string{"some-distributed-group-1", "some-distributed-group-2"}
+
 	mux := http.NewServeMux()
 	server := tlsserver.TLSTestServer(t, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		tlsserver.AssertTLS(t, r, ptls.Default)
@@ -87,6 +90,59 @@ func TestController(t *testing.T) {
 		}
 		require.NoError(t, json.NewEncoder(w).Encode(jwks))
 	}))
+	// Claims without the subject, to be used distributed claims tests.
+	// OIDC 1.0 section 5.6.2:
+	// A sub (subject) Claim SHOULD NOT be returned from the Claims Provider unless its value
+	// is an identifier for the End-User at the Claims Provider (and not for the OpenID Provider or another party);
+	// this typically means that a sub Claim SHOULD NOT be provided.
+	claimsWithoutSubject := jwt.Claims{
+		Issuer:    server.URL,
+		Audience:  []string{goodAudience},
+		Expiry:    jwt.NewNumericDate(time.Now().Add(time.Hour)),
+		NotBefore: jwt.NewNumericDate(time.Now().Add(-time.Hour)),
+		IssuedAt:  jwt.NewNumericDate(time.Now().Add(-time.Hour)),
+	}
+	mux.Handle("/claim_source", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Unfortunately we have to set this up pretty early in the test because we can't redeclare
+		// mux.Handle. This means that we can't return a different groups claim per test; we have to
+		// return both and predecide which groups are returned.
+		sig, err := jose.NewSigner(
+			jose.SigningKey{Algorithm: goodECSigningAlgo, Key: goodECSigningKey},
+			(&jose.SignerOptions{}).WithType("JWT").WithHeader("kid", goodECSigningKeyID),
+		)
+		require.NoError(t, err)
+
+		builder := jwt.Signed(sig).Claims(claimsWithoutSubject)
+
+		builder = builder.Claims(map[string]interface{}{customGroupsClaim: distributedGroups})
+		builder = builder.Claims(map[string]interface{}{"groups": distributedGroups})
+
+		distributedClaimsJwt, err := builder.CompactSerialize()
+		require.NoError(t, err)
+
+		_, err = w.Write([]byte(distributedClaimsJwt))
+		require.NoError(t, err)
+	}))
+	mux.Handle("/wrong_claim_source", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Unfortunately we have to set this up pretty early in the test because we can't redeclare
+		// mux.Handle. This means that we can't return a different groups claim per test; we have to
+		// return both and predecide which groups are returned.
+		sig, err := jose.NewSigner(
+			jose.SigningKey{Algorithm: goodECSigningAlgo, Key: goodECSigningKey},
+			(&jose.SignerOptions{}).WithType("JWT").WithHeader("kid", goodECSigningKeyID),
+		)
+		require.NoError(t, err)
+
+		builder := jwt.Signed(sig).Claims(claimsWithoutSubject)
+
+		builder = builder.Claims(map[string]interface{}{"some-other-claim": distributedGroups})
+
+		distributedClaimsJwt, err := builder.CompactSerialize()
+		require.NoError(t, err)
+
+		_, err = w.Write([]byte(distributedClaimsJwt))
+		require.NoError(t, err)
+	}))
 
 	goodIssuer := server.URL
 
@@ -108,7 +164,7 @@ func TestController(t *testing.T) {
 		Audience: goodAudience,
 		TLS:      tlsSpecFromTLSConfig(server.TLS),
 		Claims: auth1alpha1.JWTTokenClaims{
-			Groups: "my-custom-groups-claim",
+			Groups: customGroupsClaim,
 		},
 	}
 	otherJWTAuthenticatorSpec := &auth1alpha1.JWTAuthenticatorSpec{
@@ -384,6 +440,7 @@ func TestController(t *testing.T) {
 				goodUsername,
 				tt.wantUsernameClaim,
 				tt.wantGroupsClaim,
+				goodIssuer,
 			) {
 				test := test
 				t.Run(test.name, func(t *testing.T) {
@@ -418,6 +475,7 @@ func TestController(t *testing.T) {
 						&wellKnownClaims,
 						tt.wantGroupsClaim,
 						groups,
+						test.distributedGroupsClaimURL,
 						tt.wantUsernameClaim,
 						username,
 					)
@@ -447,9 +505,10 @@ func TestController(t *testing.T) {
 }
 
 // isNotInitialized checks if the error is the internally-defined "oidc: authenticator not initialized" error from
-// the underlying OIDC authenticator, which is initialized asynchronously.
+// the underlying OIDC authenticator or "verifier is not initialized" from verifying distributed claims,
+// both of which are initialized asynchronously.
 func isNotInitialized(err error) bool {
-	return err != nil && strings.Contains(err.Error(), "authenticator not initialized")
+	return err != nil && (strings.Contains(err.Error(), "authenticator not initialized") || strings.Contains(err.Error(), "verifier not initialized"))
 }
 
 func testTableForAuthenticateTokenTests(
@@ -462,6 +521,7 @@ func testTableForAuthenticateTokenTests(
 	goodUsername string,
 	expectedUsernameClaim string,
 	expectedGroupsClaim string,
+	issuer string,
 ) []struct {
 	name                      string
 	jwtClaims                 func(wellKnownClaims *jwt.Claims, groups *interface{}, username *string)
@@ -469,6 +529,7 @@ func testTableForAuthenticateTokenTests(
 	wantResponse              *authenticator.Response
 	wantAuthenticated         bool
 	wantErrorRegexp           string
+	distributedGroupsClaimURL string
 } {
 	tests := []struct {
 		name                      string
@@ -477,6 +538,7 @@ func testTableForAuthenticateTokenTests(
 		wantResponse              *authenticator.Response
 		wantAuthenticated         bool
 		wantErrorRegexp           string
+		distributedGroupsClaimURL string
 	}{
 		{
 			name: "good token without groups and with EC signature",
@@ -514,6 +576,33 @@ func testTableForAuthenticateTokenTests(
 			},
 			wantAuthenticated: true,
 		},
+		{
+			name: "good token with good distributed groups",
+			jwtClaims: func(claims *jwt.Claims, groups *interface{}, username *string) {
+			},
+			distributedGroupsClaimURL: issuer + "/claim_source",
+			wantResponse: &authenticator.Response{
+				User: &user.DefaultInfo{
+					Name:   goodUsername,
+					Groups: []string{"some-distributed-group-1", "some-distributed-group-2"},
+				},
+			},
+			wantAuthenticated: true,
+		},
+		{
+			name: "distributed groups returns a 404",
+			jwtClaims: func(claims *jwt.Claims, groups *interface{}, username *string) {
+			},
+			distributedGroupsClaimURL: issuer + "/not_found_claim_source",
+			wantErrorRegexp:           `oidc: could not expand distributed claims: while getting distributed claim "` + expectedGroupsClaim + `": error while getting distributed claim JWT: 404 Not Found`,
+		},
+		{
+			name: "distributed groups doesn't return the right claim",
+			jwtClaims: func(claims *jwt.Claims, groups *interface{}, username *string) {
+			},
+			distributedGroupsClaimURL: issuer + "/wrong_claim_source",
+			wantErrorRegexp:           `oidc: could not expand distributed claims: jwt returned by distributed claim endpoint "` + issuer + `/wrong_claim_source" did not contain claim: `,
+		},
 		{
 			name: "good token with groups as string",
 			jwtClaims: func(_ *jwt.Claims, groups *interface{}, username *string) {
@@ -644,6 +733,7 @@ func createJWT(
 	claims *jwt.Claims,
 	groupsClaim string,
 	groupsValue interface{},
+	distributedGroupsClaimURL string,
 	usernameClaim string,
 	usernameValue string,
 ) string {
@@ -659,6 +749,10 @@ func createJWT(
 	if groupsValue != nil {
 		builder = builder.Claims(map[string]interface{}{groupsClaim: groupsValue})
 	}
+	if distributedGroupsClaimURL != "" {
+		builder = builder.Claims(map[string]interface{}{"_claim_names": map[string]string{groupsClaim: "src1"}})
+		builder = builder.Claims(map[string]interface{}{"_claim_sources": map[string]interface{}{"src1": map[string]string{"endpoint": distributedGroupsClaimURL}}})
+	}
 	if usernameValue != "" {
 		builder = builder.Claims(map[string]interface{}{usernameClaim: usernameValue})
 	}