diff --git a/includes/functions.php b/includes/functions.php
index a7f348e..2da54b9 100644
--- a/includes/functions.php
+++ b/includes/functions.php
@@ -1,138 +1,173 @@
 <?php
 # Linux Day website - common functions
 # Copyright (C) 2016, 2017, 2018, 2019 Valerio Bozzolan, Ludovico Pavesi, Linux Day Torino
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License as published by
 # the Free Software Foundation, either version 3 of the License, or
 # (at your option) any later version.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU Affero General Public License for more details.
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 function license($code) {
 	return Licenses::instance()->get($code);
 }
 
 function request_uri() {
 	return URL_protocol() . URL_domain() . ROOT . $_SERVER['REQUEST_URI'];
 }
 
 /**
  * Generate a stupid MySQL COALESCE() clause to select the most appropriate i18n database column
  *
  * @param  string $name Base virtual name of the column
  * @param  mixed  $i18n Associative array of languages and column names, or a generic column name like 'column_%s', or nothing to be the "$name_%s"
  * @return string
  */
 function i18n_coalesce( $name, $i18n = null ) {
 
 	// current language (e.g. 'en')
 	$lang = latest_language()->getISO();
 
 	// default language of the website
 	$default = 'it';
 
 	if( !$i18n ) {
 		$i18n = $name . '_%s';
 	}
 
 	// allow a generic string
 	if( is_string( $i18n ) ) {
 		$generic = $i18n;
 		$i18n = [];
 		$i18n[ $lang    ] = sprintf( $generic, $lang    );
 		$i18n[ $default ] = sprintf( $generic, $default );
 	}
 
 	// base priority column name
 	$base_priority = $i18n[ $default ];
 
 	// try to catch the more specific column, then the default
 	if( $lang !== $default && isset( $i18n[ $lang ] ) ) {
 		$more_priority = $i18n[ $lang ];
 		return "COALESCE( `$more_priority`, `$base_priority` ) AS $name";
 	}
 
 	// just pick the default
 	return "`$base_priority` AS $name";
 }
 
 /**
  * Eventually redirect the request to this permalink
  *
  * It's allowed the 'lang' parameter to be present or not.
  *
  * @param  string $permalink URL of the incoming request (absolute or relative)
  * @return string
  */
 function force_permalink( $permalink ) {
 
 	// incoming URL
 	$from = BASE_URL . $_SERVER['REQUEST_URI'];
 
 	// force absolute
 	$permalink = site_page( $permalink, true );
 
 	// if it's the same request, do nothing
 	if( $from === $permalink ) {
 		return;
 	}
 
 	// do not send a 301 Moved Permanently if the language was missing (maybe the user was just redirected to his language)
 	$status = isset( $_GET['l'] )
 		? 301  // 301 Moved Permanently
 		: 303; // 303 See Other
 
 	// redirect to the correct location
 	http_redirect( $permalink, $status );
 }
 
 /**
  * Force an URL to have the language argument it it requested the page with it
  *
  * @return string
  */
 function keep_url_in_language( $url ) {
 	// force an absolute URL
 	$url = site_page( $url, true );
 
 	// current language ISO code
 	$lang = latest_language()->getISO();
 
 	// force this argument
 	return replace_url_args( $url, [
 		'l' => $lang,
 	] );
 }
 
 /**
  * Override parameters in GET query string
  *
  * @param  string $url        The entire URL (no relative URLs they confuse parse_url)
  * @param   array $parameters Associative array, with key = paramter, value = value or null to remove it
  * @return string the new query part of the URL with "?" already placed in front, or an empty string
  * @author Ludovico Pavesi
  * @since  2019-09-30
  */
 function replace_url_args( $url, $parameters ) {
 	$parsed = parse_url( $url );
 	if( isset( $parsed['query'] ) ) {
 		parse_str( $parsed['query'], $query );
 	} else {
 		$query = [];
 	}
 	foreach( $parameters as $k => $v ) {
 		if( $v === null ) {
 			unset( $query[ $k ] );
 		} else {
 			$query[ $k ] = $v;
 		}
 	}
 	return http_build_get_query( $url, $parameters );
 }
+
+
+/**
+ * Eventually ask for more privileges
+ *
+ * This redirects to the login page or throws a 403 page
+ */
+function missing_privileges() {
+
+	if( is_logged() ) {
+
+		// I do not want to spend too much time in this. Just die.
+		http_response_code( 403 );
+		echo "You are not in the sudoers file. This incident will be reported. XKCD 838.";
+		exit;
+
+	} else {
+
+		// the user needs to login
+
+		// login page URL
+		$login_url = site_page( ADMIN_URL . '/login.php' );
+
+		// current page URL
+		$current_url = $_SERVER['REQUEST_URI'] ?? null;
+
+		// build the login page URL with redirect to the current page
+		$login_url = http_build_get_query( $login_url, [
+			'redirect' => $current_url,
+		] );
+
+		// temporary redirect to the login page
+		http_redirect( $login_url );
+	}
+}