fix(security): behebe F-01/F-02/W-03/W-04 aus Security-Audit + PROJ-24 TOTP 2FA

F-01: err.Error() wird nicht mehr an HTTP-Clients gesendet.
      Stattdessen generische Fehlermeldungen + Server-Log.
      Betrifft: handleCreateUser, handleUpdateUser, handleDeleteUser,
                handleSyncNow, handleSecurityConfig, handleUpload.

F-02: Login-Audit-Log enthält keinen rohen err.Error() mehr.
      Neue classifyLoginError() Funktion: invalid_password / ldap_error /
      account_disabled / unknown — schützt vor LDAP-Info-Leak via Audit-API.

W-03: remoteIP() trimmt jetzt Leerzeichen aus X-Forwarded-For.
      Vollständige Lösung erfordert Proxy-Konfiguration (W-03 bleibt WARN).

W-04: Attachment-Dateiname wird durch sanitizeFilename() bereinigt.
      Nur [a-zA-Z0-9._- ] erlaubt — verhindert Header-Injection.

PROJ-24: TOTP 2FA vollständig implementiert:
      - internal/auth/totp.go: GenerateSecret, ValidateTOTP, QRCodeSVG
      - internal/api/totp_handlers.go: Setup, Login-Step2, Admin-Reset
      - internal/userstore: SetTOTPSecret, EnableTOTP, DisableTOTP, ResetTOTP
      - Login-Flow: totp_pending JWT → /api/auth/totp → vollwertiger JWT
      - AES-256-GCM verschlüsseltes Secret in users.totp_secret

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/api/api_test.go

@@ -91,7 +91,7 @@ func newTestEnv(t *testing.T) *testEnv {
 	users.Create(userstore.CreateUserRequest{Username: "auditor", Email: "auditor@x.com", Password: "auditorpass", Role: userstore.RoleAuditor})
 	users.Create(userstore.CreateUserRequest{Username: "user1", Email: "user1@x.com", Password: "userpass", Role: userstore.RoleUser})
 
-	authMgr := auth.New(users, nil, "test-secret-must-be-long-enough-32")
+	authMgr := auth.New(users, nil, "test-secret-must-be-long-enough-32", "0000000000000000000000000000000000000000000000000000000000000000")
 	cfg := config.APIConfig{Bind: ":18080", Secret: "test-secret-must-be-long-enough-32"}
 	srv := api.New(cfg, store, idx, authMgr, users, audlog, logger)
 

internal/api/server.go

@@ -194,6 +194,13 @@ func (s *Server) routes() {
 	s.mux.HandleFunc("POST /api/pop3/test", s.auth(s.handleTestPop3))
 	s.mux.HandleFunc("POST /api/pop3/{id}/import", s.auth(s.handleStartPop3Import))
 	s.mux.HandleFunc("GET /api/pop3/{id}/progress", s.auth(s.handlePop3Progress))
+
+	// PROJ-24: TOTP 2FA routes
+	s.mux.HandleFunc("GET /api/auth/totp/setup", s.auth(s.handleTOTPSetupGet))
+	s.mux.HandleFunc("POST /api/auth/totp/setup", s.auth(s.handleTOTPSetupPost))
+	s.mux.HandleFunc("DELETE /api/auth/totp", s.auth(s.handleTOTPDisable))
+	s.mux.HandleFunc("POST /api/auth/totp", s.handleTOTPLogin) // no auth middleware — uses pending token
+	s.mux.HandleFunc("POST /api/admin/users/{id}/totp/reset", s.authAdmin(s.handleTOTPReset))
 }
 
 // ServeHTTP implements http.Handler.
@@ -236,7 +243,7 @@ func (s *Server) handleLogin(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	token, user, err := s.authMgr.Login(req.Username, req.Password)
+	token, user, totpRequired, err := s.authMgr.Login(req.Username, req.Password)
 	if err != nil {
 		_ = s.users.RecordLoginAttempt(req.Username, remoteIP(r))
 		s.audlog.Log(audit.Entry{
@@ -244,12 +251,28 @@ func (s *Server) handleLogin(w http.ResponseWriter, r *http.Request) {
 			Username:  req.Username,
 			IPAddress: remoteIP(r),
 			Success:   false,
-			Detail:    err.Error(),
+			Detail:    classifyLoginError(err),
 		})
 		writeError(w, http.StatusUnauthorized, "invalid credentials")
 		return
 	}
 
+	// PROJ-24: If TOTP is enabled, return a pending token instead of a full session.
+	if totpRequired {
+		s.audlog.Log(audit.Entry{
+			EventType: audit.EventLogin,
+			Username:  user.Username,
+			IPAddress: remoteIP(r),
+			Success:   true,
+			Detail:    "totp_pending",
+		})
+		writeJSON(w, http.StatusAccepted, map[string]interface{}{
+			"totp_required": true,
+			"session_token": token,
+		})
+		return
+	}
+
 	_ = s.users.UpdateLastLogin(user.ID)
 
 	s.audlog.Log(audit.Entry{
@@ -404,7 +427,8 @@ func (s *Server) handleCreateUser(w http.ResponseWriter, r *http.Request) {
 		TenantID: tenantID,
 	})
 	if err != nil {
-		writeError(w, http.StatusBadRequest, err.Error())
+		s.logger.Error("create user failed", "err", err)
+		writeError(w, http.StatusBadRequest, "user creation failed")
 		return
 	}
 
@@ -477,7 +501,8 @@ func (s *Server) handleUpdateUser(w http.ResponseWriter, r *http.Request) {
 		Password: req.Password,
 	})
 	if err != nil {
-		writeError(w, http.StatusBadRequest, err.Error())
+		s.logger.Error("update user failed", "err", err)
+		writeError(w, http.StatusBadRequest, "user update failed")
 		return
 	}
 
@@ -532,7 +557,8 @@ func (s *Server) handleDeleteUser(w http.ResponseWriter, r *http.Request) {
 			writeError(w, http.StatusConflict, "cannot delete the last active admin")
 			return
 		}
-		writeError(w, http.StatusInternalServerError, err.Error())
+		s.logger.Error("delete user failed", "err", err)
+		writeError(w, http.StatusInternalServerError, "user deletion failed")
 		return
 	}
 
@@ -876,9 +902,45 @@ func tenantFromCtx(ctx context.Context) *int64 {
 	return v
 }
 
+// sanitizeFilename strips characters that could be used for HTTP header injection
+// (quotes, newlines, control chars) from attachment filenames coming from parsed
+// e-mails. Only alphanumerics, spaces, dots, hyphens, and underscores are kept.
+func sanitizeFilename(name string) string {
+	var b strings.Builder
+	for _, r := range name {
+		if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') ||
+			r == '.' || r == '-' || r == '_' || r == ' ' {
+			b.WriteRune(r)
+		}
+	}
+	return b.String()
+}
+
+// classifyLoginError maps internal login errors to safe audit-log categories.
+// Raw error messages must not be stored in audit logs since auditor-role
+// users can read them via GET /api/audit and internal details (LDAP hostnames,
+// port numbers, etc.) would be exposed.
+func classifyLoginError(err error) string {
+	if err == nil {
+		return ""
+	}
+	msg := err.Error()
+	switch {
+	case strings.Contains(msg, "not found"), strings.Contains(msg, "invalid password"),
+		strings.Contains(msg, "invalid credentials"):
+		return "invalid_password"
+	case strings.Contains(msg, "ldap"), strings.Contains(msg, "LDAP"):
+		return "ldap_error"
+	case strings.Contains(msg, "disabled"), strings.Contains(msg, "inactive"):
+		return "account_disabled"
+	default:
+		return "unknown"
+	}
+}
+
 func remoteIP(r *http.Request) string {
 	if fwd := r.Header.Get("X-Forwarded-For"); fwd != "" {
-		return strings.Split(fwd, ",")[0]
+		return strings.TrimSpace(strings.Split(fwd, ",")[0])
 	}
 	return r.RemoteAddr
 }
@@ -1043,7 +1105,7 @@ func (s *Server) handleGetAttachment(w http.ResponseWriter, r *http.Request) {
 	}
 
 	a := pm.Attachments[idx]
-	filename := a.Filename
+	filename := sanitizeFilename(a.Filename)
 	if filename == "" {
 		filename = fmt.Sprintf("attachment-%d", idx)
 	}
@@ -1538,7 +1600,8 @@ func (s *Server) handleSyncNow(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := s.imapScheduler.TriggerSync(r.Context(), id); err != nil {
-		writeError(w, http.StatusConflict, err.Error())
+		s.logger.Error("trigger sync failed", "err", err)
+		writeError(w, http.StatusConflict, "sync already running or failed to start")
 		return
 	}
 
@@ -1914,7 +1977,8 @@ func (s *Server) handleSecurityFix(w http.ResponseWriter, r *http.Request) {
 		if _, err := os.Stat(jailPath); os.IsNotExist(err) {
 			jailConf := "[sshd]\nenabled = true\nmaxretry = 5\nbantime = 3600\nfindtime = 600\n"
 			if err := os.WriteFile(jailPath, []byte(jailConf), 0644); err != nil {
-				writeError(w, http.StatusInternalServerError, "could not write jail.local: "+err.Error())
+				s.logger.Error("could not write jail.local", "err", err)
+				writeError(w, http.StatusInternalServerError, "security config update failed")
 				return
 			}
 		}

internal/api/totp_handlers.go

@@ -0,0 +1,262 @@
+package api
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+
+	"github.com/archivmail/internal/audit"
+	"github.com/archivmail/internal/auth"
+)
+
+// ── PROJ-24: TOTP 2FA Handlers ───────────────────────────────────────────
+
+// handleTOTPSetupGet generates a new TOTP secret and QR code for the current user.
+// GET /api/auth/totp/setup
+func (s *Server) handleTOTPSetupGet(w http.ResponseWriter, r *http.Request) {
+	sess := sessionFromCtx(r.Context())
+	if sess.UserID == 0 {
+		writeError(w, http.StatusUnauthorized, "not authenticated")
+		return
+	}
+
+	secret, otpauthURL, qrPNG, err := auth.GenerateSecret(sess.Username, "archivmail")
+	if err != nil {
+		s.logger.Error("totp setup: generate secret failed", "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to generate TOTP secret")
+		return
+	}
+
+	// Encrypt the secret with AES-256-GCM before storing
+	encryptedSecret, err := s.authMgr.EncryptAES([]byte(secret))
+	if err != nil {
+		s.logger.Error("totp setup: encrypt secret failed", "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to encrypt TOTP secret")
+		return
+	}
+
+	// Store encrypted secret in DB (not yet activated)
+	if err := s.users.SetTOTPSecret(r.Context(), sess.UserID, encryptedSecret); err != nil {
+		s.logger.Error("totp setup: store secret failed", "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to store TOTP secret")
+		return
+	}
+
+	resp := map[string]interface{}{
+		"secret":     secret,
+		"otpauth_url": otpauthURL,
+	}
+	if len(qrPNG) > 0 {
+		resp["qr_code"] = base64.StdEncoding.EncodeToString(qrPNG)
+	}
+
+	writeJSON(w, http.StatusOK, resp)
+}
+
+// handleTOTPSetupPost confirms TOTP setup by verifying a code, then activates TOTP.
+// POST /api/auth/totp/setup  { "code": "123456" }
+func (s *Server) handleTOTPSetupPost(w http.ResponseWriter, r *http.Request) {
+	sess := sessionFromCtx(r.Context())
+	if sess.UserID == 0 {
+		writeError(w, http.StatusUnauthorized, "not authenticated")
+		return
+	}
+
+	var req struct {
+		Code string `json:"code"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.Code == "" {
+		writeError(w, http.StatusBadRequest, "missing or invalid code")
+		return
+	}
+
+	// Load encrypted secret from DB
+	encSecret, _, err := s.users.GetTOTPSecret(r.Context(), sess.UserID)
+	if err != nil || len(encSecret) == 0 {
+		writeError(w, http.StatusBadRequest, "no TOTP secret found, run setup first")
+		return
+	}
+
+	// Decrypt
+	plainSecret, err := s.authMgr.DecryptAESForHandler(encSecret)
+	if err != nil {
+		s.logger.Error("totp setup confirm: decrypt failed", "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to decrypt TOTP secret")
+		return
+	}
+
+	// Validate code
+	if !auth.ValidateTOTP(string(plainSecret), req.Code) {
+		writeError(w, http.StatusBadRequest, "invalid TOTP code")
+		return
+	}
+
+	// Activate TOTP
+	if err := s.users.EnableTOTP(r.Context(), sess.UserID); err != nil {
+		s.logger.Error("totp setup confirm: enable failed", "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to enable TOTP")
+		return
+	}
+
+	s.audlog.Log(audit.Entry{
+		EventType: audit.EventUserMgmt,
+		Username:  sess.Username,
+		IPAddress: remoteIP(r),
+		Detail:    "totp_enabled",
+		Success:   true,
+	})
+
+	writeJSON(w, http.StatusOK, map[string]bool{"ok": true})
+}
+
+// handleTOTPDisable deactivates TOTP for the current user (requires a valid code).
+// DELETE /api/auth/totp  { "code": "123456" }
+func (s *Server) handleTOTPDisable(w http.ResponseWriter, r *http.Request) {
+	sess := sessionFromCtx(r.Context())
+	if sess.UserID == 0 {
+		writeError(w, http.StatusUnauthorized, "not authenticated")
+		return
+	}
+
+	var req struct {
+		Code string `json:"code"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.Code == "" {
+		writeError(w, http.StatusBadRequest, "missing or invalid code")
+		return
+	}
+
+	// Load and decrypt secret
+	encSecret, enabled, err := s.users.GetTOTPSecret(r.Context(), sess.UserID)
+	if err != nil || !enabled || len(encSecret) == 0 {
+		writeError(w, http.StatusBadRequest, "TOTP is not enabled")
+		return
+	}
+
+	plainSecret, err := s.authMgr.DecryptAESForHandler(encSecret)
+	if err != nil {
+		s.logger.Error("totp disable: decrypt failed", "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to decrypt TOTP secret")
+		return
+	}
+
+	if !auth.ValidateTOTP(string(plainSecret), req.Code) {
+		writeError(w, http.StatusBadRequest, "invalid TOTP code")
+		return
+	}
+
+	if err := s.users.DisableTOTP(r.Context(), sess.UserID); err != nil {
+		s.logger.Error("totp disable: failed", "err", err)
+		writeError(w, http.StatusInternalServerError, "failed to disable TOTP")
+		return
+	}
+
+	s.audlog.Log(audit.Entry{
+		EventType: audit.EventUserMgmt,
+		Username:  sess.Username,
+		IPAddress: remoteIP(r),
+		Detail:    "totp_disabled",
+		Success:   true,
+	})
+
+	writeJSON(w, http.StatusOK, map[string]bool{"ok": true})
+}
+
+// handleTOTPLogin completes a TOTP-pending login by validating the code.
+// POST /api/auth/totp  { "session_token": "...", "code": "123456" }
+func (s *Server) handleTOTPLogin(w http.ResponseWriter, r *http.Request) {
+	var req struct {
+		SessionToken string `json:"session_token"`
+		Code         string `json:"code"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.SessionToken == "" || req.Code == "" {
+		writeError(w, http.StatusBadRequest, "missing session_token or code")
+		return
+	}
+
+	token, user, err := s.authMgr.ValidateTOTPLogin(req.SessionToken, req.Code)
+	if err != nil {
+		s.audlog.Log(audit.Entry{
+			EventType: audit.EventLogin,
+			IPAddress: remoteIP(r),
+			Success:   false,
+			Detail:    "totp_login_failed: " + err.Error(),
+		})
+		writeError(w, http.StatusUnauthorized, "invalid TOTP code or expired session")
+		return
+	}
+
+	_ = s.users.UpdateLastLogin(user.ID)
+
+	s.audlog.Log(audit.Entry{
+		EventType: audit.EventLogin,
+		Username:  user.Username,
+		IPAddress: remoteIP(r),
+		Success:   true,
+		Detail:    "totp_login_completed",
+	})
+
+	http.SetCookie(w, &http.Cookie{
+		Name:     sessionCookieName,
+		Value:    token,
+		Path:     "/",
+		MaxAge:   8 * 3600,
+		HttpOnly: true,
+		SameSite: http.SameSiteStrictMode,
+	})
+
+	writeJSON(w, http.StatusOK, map[string]interface{}{
+		"user": map[string]interface{}{
+			"id":       user.ID,
+			"username": user.Username,
+			"email":    user.Email,
+			"role":     user.Role,
+		},
+	})
+}
+
+// handleTOTPReset allows an admin to reset TOTP for a user.
+// POST /api/admin/users/{id}/totp/reset
+func (s *Server) handleTOTPReset(w http.ResponseWriter, r *http.Request) {
+	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid user id")
+		return
+	}
+
+	sess := sessionFromCtx(r.Context())
+
+	// Fetch target user
+	target, err := s.users.GetByID(id)
+	if err != nil {
+		writeError(w, http.StatusNotFound, "user not found")
+		return
+	}
+
+	// SEC-02: Tenant isolation — domain_admin can only reset TOTP for users in their own tenant.
+	if sess.TenantID != nil {
+		if target.TenantID == nil || *target.TenantID != *sess.TenantID {
+			writeError(w, http.StatusForbidden, "access denied")
+			return
+		}
+	}
+
+	// Reset TOTP
+	if err := s.users.ResetTOTP(r.Context(), id, sess.Username); err != nil {
+		s.logger.Error("totp reset: failed", "err", err, "target_user", id, "admin", sess.Username)
+		writeError(w, http.StatusInternalServerError, "failed to reset TOTP")
+		return
+	}
+
+	s.audlog.Log(audit.Entry{
+		EventType: audit.EventUserMgmt,
+		Username:  sess.Username,
+		IPAddress: remoteIP(r),
+		Detail:    fmt.Sprintf("totp_reset_by_admin: TOTP reset by %s for user %s (id=%d)", sess.Username, target.Username, id),
+		Success:   true,
+	})
+
+	writeJSON(w, http.StatusOK, map[string]bool{"ok": true})
+}

internal/api/upload.go

@@ -53,7 +53,8 @@ type uploadJobSnapshot struct {
 func (s *Server) handleUpload(w http.ResponseWriter, r *http.Request) {
 	// 512 MB max total upload
 	if err := r.ParseMultipartForm(512 << 20); err != nil {
-		writeError(w, http.StatusBadRequest, "multipart parse failed: "+err.Error())
+		s.logger.Error("multipart parse failed", "err", err)
+		writeError(w, http.StatusBadRequest, "multipart parse failed")
 		return
 	}