Check for issuer if available

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

internal/oidc/token/token_handler.go

@@ -141,7 +141,7 @@ func upstreamOIDCRefresh(ctx context.Context, session *psession.PinnipedSession,
 	if len(validatedTokens.IDToken.Claims) != 0 {
 		newSub := claims["sub"]
 		oldDownstreamSubject := session.Fosite.Claims.Subject
-		oldSub, err := upstreamoidc.ExtractUpstreamSubjectFromDownstream(oldDownstreamSubject)
+		oldIss, oldSub, err := upstreamoidc.ExtractUpstreamSubjectAndIssuerFromDownstream(oldDownstreamSubject)
 		if err != nil {
 			return errorsx.WithStack(errUpstreamRefreshError.WithHintf("Upstream refresh failed.").
 				WithWrap(err).WithDebugf("provider name: %q, provider type: %q", s.ProviderName, s.ProviderType))
@@ -152,14 +152,17 @@ func upstreamOIDCRefresh(ctx context.Context, session *psession.PinnipedSession,
 		}
 		usernameClaim := p.GetUsernameClaim()
 		newUsername := claims[usernameClaim]
+		oldUsername := session.Fosite.Claims.Extra["username"]
 		// its possible this won't be returned.
 		// but if it is, verify that it hasn't changed.
-		if newUsername != nil {
-			oldUsername := session.Fosite.Claims.Extra["username"]
-			if oldUsername != newUsername {
+		if newUsername != nil && oldUsername != newUsername {
 			return errorsx.WithStack(errUpstreamRefreshError.WithHintf(
 				"Upstream refresh failed.").WithWrap(errors.New("username in upstream refresh does not match previous value")).WithDebugf("provider name: %q, provider type: %q", s.ProviderName, s.ProviderType))
 		}
+		newIssuer := claims["iss"]
+		if newIssuer != nil && oldIss != newIssuer {
+			return errorsx.WithStack(errUpstreamRefreshError.WithHintf(
+				"Upstream refresh failed.").WithWrap(errors.New("issuer in upstream refresh does not match previous value")).WithDebugf("provider name: %q, provider type: %q", s.ProviderName, s.ProviderType))
 		}
 	}
 

internal/oidc/token/token_handler_test.go

@@ -1706,6 +1706,37 @@ func TestRefreshGrant(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "refresh grant with changed issuer claim",
+			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithOIDC(
+				upstreamOIDCIdentityProviderBuilder().WithUsernameClaim("username-claim").WithValidatedTokens(&oidctypes.Token{
+					IDToken: &oidctypes.IDToken{
+						Claims: map[string]interface{}{
+							"some-claim": "some-value",
+							"sub":        "some-subject",
+							"iss":        "some-changed-issuer",
+						},
+					},
+				}).WithRefreshedTokens(refreshedUpstreamTokensWithIDAndRefreshTokens()).Build()),
+			authcodeExchange: authcodeExchangeInputs{
+				customSessionData: initialUpstreamOIDCCustomSessionData(),
+				modifyAuthRequest: func(r *http.Request) { r.Form.Set("scope", "openid offline_access") },
+				want:              happyAuthcodeExchangeTokenResponseForOpenIDAndOfflineAccess(initialUpstreamOIDCCustomSessionData()),
+			},
+			refreshRequest: refreshRequestInputs{
+				want: tokenEndpointResponseExpectedValues{
+					wantUpstreamRefreshCall:           happyOIDCUpstreamRefreshCall(),
+					wantUpstreamOIDCValidateTokenCall: happyUpstreamValidateTokenCall(refreshedUpstreamTokensWithIDAndRefreshTokens()),
+					wantStatus:                        http.StatusUnauthorized,
+					wantErrorResponseBody: here.Doc(`
+						{
+							"error":             "error",
+							"error_description": "Error during upstream refresh. Upstream refresh failed."
+						}
+					`),
+				},
+			},
+		},
 		{
 			name: "upstream ldap refresh happy path",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&oidctestutil.TestUpstreamLDAPIdentityProvider{

internal/upstreamoidc/upstreamoidc.go

@@ -238,11 +238,12 @@ func (p *ProviderConfig) tryRevokeRefreshToken(
 	}
 }
 
-func ExtractUpstreamSubjectFromDownstream(downstreamSubject string) (string, error) {
+func ExtractUpstreamSubjectAndIssuerFromDownstream(downstreamSubject string) (string, string, error) {
 	if !strings.Contains(downstreamSubject, "?sub=") {
-		return "", errors.New("downstream subject did not contain original upstream subject")
+		return "", "", errors.New("downstream subject did not contain original upstream subject")
 	}
-	return strings.SplitN(downstreamSubject, "?sub=", 2)[1], nil
+	split := strings.SplitN(downstreamSubject, "?sub=", 2)
+	return split[0], split[1], nil
 }
 
 // ValidateToken will validate the ID token. It will also merge the claims from the userinfo endpoint response,

internal/upstreamoidc/upstreamoidc_test.go

@@ -910,22 +910,37 @@ func TestProviderConfig(t *testing.T) {
 		}
 	})
 
-	t.Run("ExtractUpstreamSubjectFromDownstream", func(t *testing.T) {
+	t.Run("ExtractUpstreamSubjectAndIssuerFromDownstream", func(t *testing.T) {
 		tests := []struct {
 			name                string
 			downstreamSubject   string
 			wantUpstreamSubject string
+			wantUpstreamIssuer  string
 			wantErr             string
 		}{
 			{
 				name:                "happy path",
 				downstreamSubject:   "https://some-issuer?sub=some-subject",
 				wantUpstreamSubject: "some-subject",
+				wantUpstreamIssuer:  "https://some-issuer",
+			},
+			{
+				name:                "happy path but sub is empty string", // todo i think this should not be the responsibility of this function, even though it's undesirable behavior...
+				downstreamSubject:   "https://some-issuer?sub=",
+				wantUpstreamSubject: "",
+				wantUpstreamIssuer:  "https://some-issuer",
+			},
+			{
+				name:                "happy path but iss is empty string",
+				downstreamSubject:   "?sub=some-subject",
+				wantUpstreamSubject: "some-subject",
+				wantUpstreamIssuer:  "",
 			},
 			{
 				name:                "subject in a subject",
 				downstreamSubject:   "https://some-other-issuer?sub=https://some-issuer?sub=some-subject",
 				wantUpstreamSubject: "https://some-issuer?sub=some-subject",
+				wantUpstreamIssuer:  "https://some-other-issuer",
 			},
 			{
 				name:              "doesn't contain sub=",
@@ -936,17 +951,17 @@ func TestProviderConfig(t *testing.T) {
 		for _, tt := range tests {
 			tt := tt
 			t.Run(tt.name, func(t *testing.T) {
-				actualUpstreamSubject, err := ExtractUpstreamSubjectFromDownstream(tt.downstreamSubject)
+				actualUpstreamIssuer, actualUpstreamSubject, err := ExtractUpstreamSubjectAndIssuerFromDownstream(tt.downstreamSubject)
 				if tt.wantErr != "" {
 					require.Error(t, err)
 					require.Equal(t, tt.wantErr, err.Error())
 				} else {
 					require.NoError(t, err)
 					require.Equal(t, tt.wantUpstreamSubject, actualUpstreamSubject)
+					require.Equal(t, tt.wantUpstreamIssuer, actualUpstreamIssuer)
 				}
 			})
 		}
-
 	})
 
 	t.Run("ExchangeAuthcodeAndValidateTokens", func(t *testing.T) {