Support login in through REMOTE_USER environment variable

Support redirecting remote users to logout URL and clearing remote login cookies

powerdnsadmin/routes/base.py

@@ -28,6 +28,19 @@ def handle_internal_server_error(e):
     return render_template('errors/500.html', code=500, message=e), 500
 
 
+def load_if_valid(user, method, src_ip, trust_user = False):
+    try:
+        auth = user.is_validate(method, src_ip, trust_user)
+        if auth == False:
+            return None
+        else:
+            # login_user(user, remember=False)
+            return User.query.filter(User.id==user.id).first()
+    except Exception as e:
+        current_app.logger.error('Error: {0}'.format(e))
+        return None
+
+
 @login_manager.user_loader
 def load_user(id):
     """
@@ -37,29 +50,42 @@ def load_user(id):
 
 
 @login_manager.request_loader
-def login_via_authorization_header(request):
+def login_via_authorization_header_or_remote_user(request):
+    # Try to login using Basic Authentication
     auth_header = request.headers.get('Authorization')
     if auth_header:
+        auth_method = request.args.get('auth_method', 'LOCAL')
+        auth_method = 'LDAP' if auth_method != 'LOCAL' else 'LOCAL'
         auth_header = auth_header.replace('Basic ', '', 1)
         try:
             auth_header = str(base64.b64decode(auth_header), 'utf-8')
             username, password = auth_header.split(":")
         except TypeError as e:
             return None
+
         user = User(username=username,
                     password=password,
                     plain_text_password=password)
-        try:
-            auth_method = request.args.get('auth_method', 'LOCAL')
-            auth_method = 'LDAP' if auth_method != 'LOCAL' else 'LOCAL'
-            auth = user.is_validate(method=auth_method,
-                                    src_ip=request.remote_addr)
-            if auth == False:
-                return None
-            else:
-                # login_user(user, remember=False)
-                return User.query.filter(User.id==user.id).first()
-        except Exception as e:
-            current_app.logger.error('Error: {0}'.format(e))
-            return None
+        return load_if_valid(user, method=auth_method, src_ip=request.remote_addr)
+    
+    # Try login by checking a REMOTE_USER environment variable
+    remote_user = request.remote_user
+    if remote_user and current_app.config.get('REMOTE_USER_ENABLED'):
+        session_remote_user = session.get('remote_user')
+        
+        # If we already validated a remote user against an authorization method
+        # a local user should have been created in the database, so we force a 'LOCAL' auth_method
+        auth_method = 'LOCAL' if session_remote_user else current_app.config.get('REMOTE_AUTH_METHOD', 'LDAP') 
+        current_app.logger.debug(
+            'REMOTE_USER environment variable found: attempting {0} authentication for username "{1}"'
+            .format(auth_method, remote_user))
+        user = User(username=remote_user.strip())
+        valid_remote_user = load_if_valid(user, method=auth_method, src_ip=request.remote_addr, trust_user=True)
+        
+        if valid_remote_user:
+            # If we were successful in authenticating a trusted remote user, store it in session
+            session['remote_user'] = valid_remote_user.username
+
+        return valid_remote_user
+
     return None

powerdnsadmin/routes/index.py

@@ -377,8 +377,9 @@ def clear_session():
     session.pop('github_token', None)
     session.pop('google_token', None)
     session.pop('authentication_type', None)
-    session.clear()
+    session.pop('remote_user', None)
     logout_user()
+    session.clear()
 
 
 def signin_history(username, authenticator, success):
@@ -434,7 +435,30 @@ def logout():
                 "urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress",
                 session_index=session['samlSessionIndex'],
                 name_id=session['samlNameId']))
+
+    # Clean cookies and flask session
     clear_session()
+
+    # If remote user authentication is enabled and a logout URL is configured for it,
+    # redirect users to that instead
+    remote_user_logout_url = current_app.config.get('REMOTE_USER_LOGOUT_URL')
+    if current_app.config.get('REMOTE_USER_ENABLED') and remote_user_logout_url:
+        current_app.logger.debug(
+            'Redirecting remote user "{0}" to logout URL {1}'
+            .format(current_user.username, remote_user_logout_url))
+        # Warning: if REMOTE_USER environment variable is still set and not cleared by
+        # some external module, not defining a custom logout URL will trigger a loop
+        # that will just log the user back in right after logging out
+        res = make_response(redirect(remote_user_logout_url.strip()))
+
+        # Remove any custom cookies the remote authentication mechanism may use
+        # (e.g.: MOD_AUTH_CAS and MOD_AUTH_CAS_S)
+        remote_cookies = current_app.config.get('REMOTE_USER_COOKIES')
+        for r_cookie_name in utils.ensure_list(remote_cookies):
+            res.delete_cookie(r_cookie_name)
+        
+        return res
+
     return redirect(url_for('index.login'))