[client] Force interactive login when extending the auth session

A session extend must be answered from the account the peer is registered
under. With a silent PKCE flow (DisablePromptLogin or max_age=0) the IdP
answers from whatever session it already holds, which need not be the
peer's account when several are signed in; the token then fails the
user match in ExtendAuthSession with no way to pick another account.

Mark the PKCE flow request as a session extend so the management server
can force prompt=login for it, overriding the configured silent flow.

client/android/login.go

@@ -199,7 +199,15 @@ type loginHintSetter interface {
 }
 
 func (a *Auth) foregroundGetTokenInfo(authClient *auth.Auth, urlOpener URLOpener, isAndroidTV bool) (*auth.TokenInfo, error) {
-	oAuthFlow, err := authClient.GetOAuthFlow(a.ctx, isAndroidTV)
+	return a.foregroundGetTokenInfoFlow(authClient, urlOpener, isAndroidTV, false)
+}
+
+// foregroundGetTokenInfoFlow runs the interactive flow. sessionExtend tells the
+// server the token will renew this peer's session rather than log a peer in, so
+// it can rule out a silent authorization the IdP could answer from an unrelated
+// account. See PKCEAuthorizationFlowRequest.
+func (a *Auth) foregroundGetTokenInfoFlow(authClient *auth.Auth, urlOpener URLOpener, isAndroidTV bool, sessionExtend bool) (*auth.TokenInfo, error) {
+	oAuthFlow, err := authClient.GetOAuthFlow(a.ctx, isAndroidTV, sessionExtend)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get OAuth flow: %v", err)
 	}

client/android/session.go

@@ -293,11 +293,13 @@ func (c *Client) extendAuthSession(ctx context.Context, urlOpener URLOpener, isA
 	}
 	defer authClient.Close()
 
-	// Passing the config path makes the flow pick up the login_hint: an extend
-	// renews the session of the account already signed in, so it must not stop to
-	// offer a choice.
+	// Passing the config path makes the flow pick up the login_hint. That alone
+	// cannot keep the IdP on this profile's account though — a hint is only a
+	// suggestion, and a silent authorization is answered from whatever session the
+	// IdP already has, which need not be this peer's when several accounts are
+	// signed in. Marking the flow as an extend lets the server rule that out.
 	a := NewAuthWithConfig(ctx, cfg, cfgPath)
-	tokenInfo, err := a.foregroundGetTokenInfo(authClient, urlOpener, isAndroidTV)
+	tokenInfo, err := a.foregroundGetTokenInfoFlow(authClient, urlOpener, isAndroidTV, true)
 	if err != nil {
 		return fmt.Errorf("interactive sso login failed: %v", err)
 	}

client/cmd/login.go

@@ -408,7 +408,7 @@ func foregroundGetTokenInfo(ctx context.Context, cmd *cobra.Command, config *pro
 		hint = profileState.Email
 	}
 
-	oAuthFlow, err := auth.NewOAuthFlow(ctx, config, util.HasGraphicalSession(), false, hint)
+	oAuthFlow, err := auth.NewOAuthFlow(ctx, config, util.HasGraphicalSession(), false, hint, false)
 	if err != nil {
 		return nil, err
 	}

client/internal/auth/auth.go

@@ -103,7 +103,7 @@ func (a *Auth) IsSSOSupported(ctx context.Context) (bool, error) {
 
 	err := a.withRetry(ctx, func(client *mgm.GrpcClient) error {
 		// Try PKCE flow first
-		_, err := a.getPKCEFlow(client)
+		_, err := a.getPKCEFlow(client, false)
 		if err == nil {
 			supportsSSO = true
 			return nil
@@ -138,7 +138,11 @@ func (a *Auth) IsSSOSupported(ctx context.Context) (bool, error) {
 
 // GetOAuthFlow returns an OAuth flow (PKCE or Device) using the existing management connection
 // This avoids creating a new connection to the management server
-func (a *Auth) GetOAuthFlow(ctx context.Context, forceDeviceAuth bool) (OAuthFlow, error) {
+//
+// sessionExtend marks the flow as renewing an existing peer's session rather than
+// logging one in; the server needs it to rule out a silent authorization that the
+// IdP could answer from another account. See PKCEAuthorizationFlowRequest.
+func (a *Auth) GetOAuthFlow(ctx context.Context, forceDeviceAuth bool, sessionExtend bool) (OAuthFlow, error) {
 	var flow OAuthFlow
 	var err error
 
@@ -149,7 +153,7 @@ func (a *Auth) GetOAuthFlow(ctx context.Context, forceDeviceAuth bool) (OAuthFlo
 		}
 
 		// Try PKCE flow first
-		flow, err = a.getPKCEFlow(client)
+		flow, err = a.getPKCEFlow(client, sessionExtend)
 		if err != nil {
 			// If PKCE not supported, try Device flow
 			if s, ok := status.FromError(err); ok && (s.Code() == codes.NotFound || s.Code() == codes.Unimplemented) {
@@ -229,8 +233,8 @@ func (a *Auth) Login(ctx context.Context, setupKey string, jwtToken string) (err
 }
 
 // getPKCEFlow retrieves PKCE authorization flow configuration and creates a flow instance
-func (a *Auth) getPKCEFlow(client *mgm.GrpcClient) (*PKCEAuthorizationFlow, error) {
-	protoFlow, err := client.GetPKCEAuthorizationFlow()
+func (a *Auth) getPKCEFlow(client *mgm.GrpcClient, sessionExtend bool) (*PKCEAuthorizationFlow, error) {
+	protoFlow, err := client.GetPKCEAuthorizationFlow(sessionExtend)
 	if err != nil {
 		if s, ok := status.FromError(err); ok && s.Code() == codes.NotFound {
 			log.Warnf("server couldn't find pkce flow, contact admin: %v", err)

client/internal/auth/oauth.go

@@ -70,12 +70,15 @@ func shouldUseDeviceFlow(force bool, isUnixDesktopClient bool) bool {
 //
 // On Linux distros without desktop environment support, it only tries to initialize the Device Code Flow
 // forceDeviceCodeFlow can be used to skip PKCE and go directly to Device Code Flow (e.g., for Android TV)
-func NewOAuthFlow(ctx context.Context, config *profilemanager.Config, isUnixDesktopClient bool, forceDeviceCodeFlow bool, hint string) (OAuthFlow, error) {
+//
+// sessionExtend marks the flow as renewing an existing peer's session rather than
+// logging one in; see PKCEAuthorizationFlowRequest for what the server makes of it.
+func NewOAuthFlow(ctx context.Context, config *profilemanager.Config, isUnixDesktopClient bool, forceDeviceCodeFlow bool, hint string, sessionExtend bool) (OAuthFlow, error) {
 	if shouldUseDeviceFlow(forceDeviceCodeFlow, isUnixDesktopClient) {
 		return authenticateWithDeviceCodeFlow(ctx, config, hint)
 	}
 
-	pkceFlow, err := authenticateWithPKCEFlow(ctx, config, hint)
+	pkceFlow, err := authenticateWithPKCEFlow(ctx, config, hint, sessionExtend)
 	if err != nil {
 		log.Debugf("failed to initialize pkce authentication with error: %v\n", err)
 		log.Debug("falling back to device code flow")
@@ -85,14 +88,14 @@ func NewOAuthFlow(ctx context.Context, config *profilemanager.Config, isUnixDesk
 }
 
 // authenticateWithPKCEFlow initializes the Proof Key for Code Exchange flow auth flow
-func authenticateWithPKCEFlow(ctx context.Context, config *profilemanager.Config, hint string) (OAuthFlow, error) {
+func authenticateWithPKCEFlow(ctx context.Context, config *profilemanager.Config, hint string, sessionExtend bool) (OAuthFlow, error) {
 	authClient, err := NewAuth(ctx, config.PrivateKey, config.ManagementURL, config)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create auth client: %v", err)
 	}
 	defer authClient.Close()
 
-	pkceFlowInfo, err := authClient.getPKCEFlow(authClient.client)
+	pkceFlowInfo, err := authClient.getPKCEFlow(authClient.client, sessionExtend)
 	if err != nil {
 		return nil, fmt.Errorf("getting pkce authorization flow info failed with error: %v", err)
 	}

client/ios/NetBirdSDK/client.go

@@ -429,7 +429,7 @@ func (c *Client) LoginForMobile() string {
 		return fmt.Sprintf("failed to load config: %v", err)
 	}
 
-	oAuthFlow, err := auth.NewOAuthFlow(ctx, cfg, false, false, "")
+	oAuthFlow, err := auth.NewOAuthFlow(ctx, cfg, false, false, "", false)
 	if err != nil {
 		return err.Error()
 	}

client/ios/NetBirdSDK/login.go

@@ -323,7 +323,7 @@ func (a *Auth) login(urlOpener URLOpener, forceDeviceAuth bool, deviceName strin
 const authInfoRequestTimeout = 30 * time.Second
 
 func (a *Auth) foregroundGetTokenInfo(authClient *auth.Auth, urlOpener URLOpener, forceDeviceAuth bool) (*auth.TokenInfo, error) {
-	oAuthFlow, err := authClient.GetOAuthFlow(a.ctx, forceDeviceAuth)
+	oAuthFlow, err := authClient.GetOAuthFlow(a.ctx, forceDeviceAuth, false)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get OAuth flow: %v", err)
 	}

client/server/server.go

@@ -679,7 +679,7 @@ func (s *Server) Login(callerCtx context.Context, msg *proto.LoginRequest) (*pro
 		if msg.Hint != nil {
 			hint = *msg.Hint
 		}
-		oAuthFlow, err := auth.NewOAuthFlow(ctx, config, msg.IsUnixDesktopClient, false, hint)
+		oAuthFlow, err := auth.NewOAuthFlow(ctx, config, msg.IsUnixDesktopClient, false, hint, false)
 		if err != nil {
 			state.Set(internal.StatusLoginFailed)
 			return nil, err
@@ -1724,7 +1724,7 @@ func (s *Server) RequestJWTAuth(
 	}
 
 	// the daemon has no graphical session of its own, only the caller can answer this
-	oAuthFlow, err := auth.NewOAuthFlow(ctx, config, msg.GetHasGraphicalSession(), false, hint)
+	oAuthFlow, err := auth.NewOAuthFlow(ctx, config, msg.GetHasGraphicalSession(), false, hint, false)
 	if err != nil {
 		return nil, gstatus.Errorf(codes.Internal, "failed to create OAuth flow: %v", err)
 	}
@@ -1828,7 +1828,7 @@ func (s *Server) RequestExtendAuthSession(
 	}
 
 	// the daemon has no graphical session of its own, only the caller can answer this
-	oAuthFlow, err := auth.NewOAuthFlow(ctx, config, msg.GetHasGraphicalSession(), false, hint)
+	oAuthFlow, err := auth.NewOAuthFlow(ctx, config, msg.GetHasGraphicalSession(), false, hint, true)
 	if err != nil {
 		return nil, gstatus.Errorf(codes.Internal, "failed to create OAuth flow: %v", err)
 	}