OIDC - support IdP logout (#670)

* OIDC - support IdP logout

Signed-off-by: Michael Tupitsyn <michael.tupitsyn@gmail.com>

* Add support of logout_idp_session parameter

Signed-off-by: Michael Tupitsyn <michael.tupitsyn@gmail.com>

* Fix merge conflict issue

Signed-off-by: Michael Tupitsyn <michael.tupitsyn@gmail.com>

* Restore original package-lock.json

Signed-off-by: Michael Tupitsyn <michael.tupitsyn@gmail.com>

* Cleanup

---------

Signed-off-by: Michael Tupitsyn <michael.tupitsyn@gmail.com>
Co-authored-by: Christoph Haas <christoph.h@sprinternet.at>

internal/app/api/v0/handlers/endpoint_authentication.go

@@ -25,7 +25,9 @@ type AuthenticationService interface {
 	// OauthLoginStep1 initiates the OAuth login flow.
 	OauthLoginStep1(_ context.Context, providerId string) (authCodeUrl, state, nonce string, err error)
 	// OauthLoginStep2 completes the OAuth login flow and logins the user in.
-	OauthLoginStep2(ctx context.Context, providerId, nonce, code string) (*domain.User, error)
+	OauthLoginStep2(ctx context.Context, providerId, nonce, code string) (*domain.User, string, error)
+	// OauthProviderLogoutUrl returns an IdP logout URL for the given provider if supported.
+	OauthProviderLogoutUrl(providerId, idTokenHint, postLogoutRedirectUri string) (string, bool)
 }
 
 type WebAuthnService interface {
@@ -331,7 +333,7 @@ func (e AuthEndpoint) handleOauthCallbackGet() http.HandlerFunc {
 		}
 
 		loginCtx, cancel := context.WithTimeout(context.Background(), 30*time.Second) // avoid long waits
-		user, err := e.authService.OauthLoginStep2(loginCtx, provider, currentSession.OauthNonce,
+		user, idTokenHint, err := e.authService.OauthLoginStep2(loginCtx, provider, currentSession.OauthNonce,
 			oauthCode)
 		cancel()
 		if err != nil {
@@ -346,7 +348,7 @@ func (e AuthEndpoint) handleOauthCallbackGet() http.HandlerFunc {
 			return
 		}
 
-		e.setAuthenticatedUser(r, user)
+		e.setAuthenticatedUser(r, user, provider, idTokenHint)
 
 		if returnUrl != nil && e.isValidReturnUrl(returnUrl.String()) {
 			queryParams := returnUrl.Query()
@@ -359,7 +361,7 @@ func (e AuthEndpoint) handleOauthCallbackGet() http.HandlerFunc {
 	}
 }
 
-func (e AuthEndpoint) setAuthenticatedUser(r *http.Request, user *domain.User) {
+func (e AuthEndpoint) setAuthenticatedUser(r *http.Request, user *domain.User, oauthProvider, idTokenHint string) {
 	// start a fresh session
 	e.session.DestroyData(r.Context())
 
@@ -374,8 +376,9 @@ func (e AuthEndpoint) setAuthenticatedUser(r *http.Request, user *domain.User) {
 
 	currentSession.OauthState = ""
 	currentSession.OauthNonce = ""
-	currentSession.OauthProvider = ""
+	currentSession.OauthProvider = oauthProvider
 	currentSession.OauthReturnTo = ""
+	currentSession.OauthIdToken = idTokenHint
 
 	e.session.SetData(r.Context(), currentSession)
 }
@@ -418,7 +421,7 @@ func (e AuthEndpoint) handleLoginPost() http.HandlerFunc {
 			return
 		}
 
-		e.setAuthenticatedUser(r, user)
+		e.setAuthenticatedUser(r, user, "", "")
 
 		respond.JSON(w, http.StatusOK, user)
 	}
@@ -430,19 +433,33 @@ func (e AuthEndpoint) handleLoginPost() http.HandlerFunc {
 // @Tags Authentication
 // @Summary Get all available external login providers.
 // @Produce json
-// @Success 200 {object} model.Error
+// @Success 200 {object} model.LogoutResponse
 // @Router /auth/logout [post]
 func (e AuthEndpoint) handleLogoutPost() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		currentSession := e.session.GetData(r.Context())
 
 		if !currentSession.LoggedIn { // Not logged in
-			respond.JSON(w, http.StatusOK, model.Error{Code: http.StatusOK, Message: "not logged in"})
+			respond.JSON(w, http.StatusOK, model.LogoutResponse{Message: "not logged in"})
 			return
 		}
 
+		postLogoutRedirectUri := e.cfg.Web.ExternalUrl
+		if e.cfg.Web.BasePath != "" {
+			postLogoutRedirectUri += e.cfg.Web.BasePath
+		}
+		postLogoutRedirectUri += "/#/login"
+
+		var redirectUrl *string
+		if currentSession.OauthProvider != "" {
+			if idpLogoutUrl, ok := e.authService.OauthProviderLogoutUrl(currentSession.OauthProvider,
+				currentSession.OauthIdToken, postLogoutRedirectUri); ok {
+				redirectUrl = &idpLogoutUrl
+			}
+		}
+
 		e.session.DestroyData(r.Context())
-		respond.JSON(w, http.StatusOK, model.Error{Code: http.StatusOK, Message: "logout ok"})
+		respond.JSON(w, http.StatusOK, model.LogoutResponse{Message: "logout ok", RedirectUrl: redirectUrl})
 	}
 }
 
@@ -693,7 +710,7 @@ func (e AuthEndpoint) handleWebAuthnLoginFinish() http.HandlerFunc {
 			return
 		}
 
-		e.setAuthenticatedUser(r, user)
+		e.setAuthenticatedUser(r, user, "", "")
 
 		respond.JSON(w, http.StatusOK, model.NewUser(user, false))
 	}

internal/app/api/v0/handlers/web_session.go

@@ -30,6 +30,7 @@ type SessionData struct {
 	OauthNonce    string
 	OauthProvider string
 	OauthReturnTo string
+	OauthIdToken  string
 
 	WebAuthnData string
 
@@ -89,5 +90,6 @@ func (s *SessionWrapper) defaultSessionData() SessionData {
 		OauthNonce:     "",
 		OauthProvider:  "",
 		OauthReturnTo:  "",
+		OauthIdToken:   "",
 	}
 }

internal/app/api/v0/model/models_authentication.go

@@ -45,6 +45,11 @@ type OauthInitiationResponse struct {
 	State       string
 }
 
+type LogoutResponse struct {
+	Message     string  `json:"Message"`
+	RedirectUrl *string `json:"RedirectUrl,omitempty"`
+}
+
 type WebAuthnCredentialRequest struct {
 	Name string `json:"Name"`
 }

internal/app/auth/auth.go

@@ -68,6 +68,8 @@ type AuthenticatorOauth interface {
 	// GetAllowedUserGroups returns the list of whitelisted user groups.
 	// If non-empty, at least one user group must match.
 	GetAllowedUserGroups() []string
+	// GetLogoutUrl returns an IdP logout URL if supported by the provider.
+	GetLogoutUrl(idTokenHint, postLogoutRedirectUri string) (string, bool)
 }
 
 // AuthenticatorLdap is the interface for all LDAP authenticators.
@@ -529,33 +531,34 @@ func isAnyAllowedUserGroup(userGroups, allowedUserGroups []string) bool {
 
 // OauthLoginStep2 finishes the oauth authentication flow by exchanging the code for an access token and
 // fetching the user information.
-func (a *Authenticator) OauthLoginStep2(ctx context.Context, providerId, nonce, code string) (*domain.User, error) {
+func (a *Authenticator) OauthLoginStep2(ctx context.Context, providerId, nonce, code string) (*domain.User, string, error) {
 	oauthProvider, ok := a.oauthAuthenticators[providerId]
 	if !ok {
-		return nil, fmt.Errorf("missing oauth provider %s", providerId)
+		return nil, "", fmt.Errorf("missing oauth provider %s", providerId)
 	}
 
 	oauth2Token, err := oauthProvider.Exchange(ctx, code)
 	if err != nil {
-		return nil, fmt.Errorf("unable to exchange code: %w", err)
+		return nil, "", fmt.Errorf("unable to exchange code: %w", err)
 	}
+	idTokenHint, _ := oauth2Token.Extra("id_token").(string)
 
 	rawUserInfo, err := oauthProvider.GetUserInfo(ctx, oauth2Token, nonce)
 	if err != nil {
-		return nil, fmt.Errorf("unable to fetch user information: %w", err)
+		return nil, "", fmt.Errorf("unable to fetch user information: %w", err)
 	}
 
 	userInfo, err := oauthProvider.ParseUserInfo(rawUserInfo)
 	if err != nil {
-		return nil, fmt.Errorf("unable to parse user information: %w", err)
+		return nil, "", fmt.Errorf("unable to parse user information: %w", err)
 	}
 
 	if !isDomainAllowed(userInfo.Email, oauthProvider.GetAllowedDomains()) {
-		return nil, fmt.Errorf("user %s is not in allowed domains", userInfo.Email)
+		return nil, "", fmt.Errorf("user %s is not in allowed domains", userInfo.Email)
 	}
 
 	if !isAnyAllowedUserGroup(userInfo.UserGroups, oauthProvider.GetAllowedUserGroups()) {
-		return nil, fmt.Errorf("user %s is not in allowed user groups", userInfo.Identifier)
+		return nil, "", fmt.Errorf("user %s is not in allowed user groups", userInfo.Identifier)
 	}
 
 	ctx = domain.SetUserInfo(ctx,
@@ -571,7 +574,7 @@ func (a *Authenticator) OauthLoginStep2(ctx context.Context, providerId, nonce,
 				Error:    err.Error(),
 			},
 		})
-		return nil, fmt.Errorf("unable to process user information: %w", err)
+		return nil, "", fmt.Errorf("unable to process user information: %w", err)
 	}
 
 	if user.IsLocked() || user.IsDisabled() {
@@ -583,7 +586,7 @@ func (a *Authenticator) OauthLoginStep2(ctx context.Context, providerId, nonce,
 				Error:    "user is locked",
 			},
 		})
-		return nil, errors.New("user is locked")
+		return nil, "", errors.New("user is locked")
 	}
 
 	a.bus.Publish(app.TopicAuthLogin, user.Identifier)
@@ -595,7 +598,16 @@ func (a *Authenticator) OauthLoginStep2(ctx context.Context, providerId, nonce,
 		},
 	})
 
-	return user, nil
+	return user, idTokenHint, nil
+}
+
+func (a *Authenticator) OauthProviderLogoutUrl(providerId, idTokenHint, postLogoutRedirectUri string) (string, bool) {
+	oauthProvider, ok := a.oauthAuthenticators[providerId]
+	if !ok {
+		return "", false
+	}
+
+	return oauthProvider.GetLogoutUrl(idTokenHint, postLogoutRedirectUri)
 }
 
 func (a *Authenticator) processUserInfo(

internal/app/auth/auth_oauth.go

@@ -79,6 +79,10 @@ func (p PlainOauthAuthenticator) GetAllowedUserGroups() []string {
 	return p.allowedUserGroups
 }
 
+func (p PlainOauthAuthenticator) GetLogoutUrl(_, _ string) (string, bool) {
+	return "", false
+}
+
 // RegistrationEnabled returns whether registration is enabled for the OAuth authenticator.
 func (p PlainOauthAuthenticator) RegistrationEnabled() bool {
 	return p.registrationEnabled

internal/app/auth/auth_oidc.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"net/url"
 
 	"github.com/coreos/go-oidc/v3/oidc"
 	"golang.org/x/oauth2"
@@ -27,6 +28,8 @@ type OidcAuthenticator struct {
 	sensitiveInfoLogging bool
 	allowedDomains       []string
 	allowedUserGroups    []string
+	endSessionEndpoint   string
+	logoutIdpSession     bool
 }
 
 func newOidcAuthenticator(
@@ -63,6 +66,16 @@ func newOidcAuthenticator(
 	provider.sensitiveInfoLogging = cfg.LogSensitiveInfo
 	provider.allowedDomains = cfg.AllowedDomains
 	provider.allowedUserGroups = cfg.AllowedUserGroups
+	provider.logoutIdpSession = cfg.LogoutIdpSession == nil || *cfg.LogoutIdpSession
+
+	var providerMetadata struct {
+		EndSessionEndpoint string `json:"end_session_endpoint"`
+	}
+	if err = provider.provider.Claims(&providerMetadata); err != nil {
+		slog.Debug("OIDC: failed to parse provider metadata", "provider", cfg.ProviderName, "error", err)
+	} else {
+		provider.endSessionEndpoint = providerMetadata.EndSessionEndpoint
+	}
 
 	return provider, nil
 }
@@ -80,6 +93,34 @@ func (o OidcAuthenticator) GetAllowedUserGroups() []string {
 	return o.allowedUserGroups
 }
 
+func (o OidcAuthenticator) GetLogoutUrl(idTokenHint, postLogoutRedirectUri string) (string, bool) {
+	if !o.logoutIdpSession {
+		return "", false
+	}
+	if o.endSessionEndpoint == "" {
+		slog.Debug("OIDC logout URL generation disabled: provider has no end_session_endpoint", "provider", o.name)
+		return "", false
+	}
+
+	logoutUrl, err := url.Parse(o.endSessionEndpoint)
+	if err != nil {
+		slog.Debug("OIDC logout URL generation failed, unable to parse end_session_endpoint url",
+			"provider", o.name, "error", err)
+		return "", false
+	}
+
+	params := logoutUrl.Query()
+	if idTokenHint != "" {
+		params.Set("id_token_hint", idTokenHint)
+	}
+	if postLogoutRedirectUri != "" {
+		params.Set("post_logout_redirect_uri", postLogoutRedirectUri)
+	}
+	logoutUrl.RawQuery = params.Encode()
+
+	return logoutUrl.String(), true
+}
+
 // RegistrationEnabled returns whether registration is enabled for this authenticator.
 func (o OidcAuthenticator) RegistrationEnabled() bool {
 	return o.registrationEnabled

internal/config/auth.go

@@ -278,6 +278,11 @@ type OpenIDConnectProvider struct {
 	// If LogSensitiveInfo is set to true, sensitive information retrieved from the OIDC provider will be logged in trace level.
 	// This also includes OAuth tokens! Keep this disabled in production!
 	LogSensitiveInfo bool `yaml:"log_sensitive_info"`
+
+	// LogoutIdpSession controls whether the user's session at the OIDC provider is terminated on logout.
+	// If set to true (default), the user will be redirected to the IdP's end_session_endpoint after local logout.
+	// If set to false, only the local wg-portal session is invalidated.
+	LogoutIdpSession *bool `yaml:"logout_idp_session"`
 }
 
 // OAuthProvider contains the configuration for the OAuth provider.