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friendica_2020-09-1_sharedH.../src/Util/Security.php

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PHP

<?php
/**
* @file /src/Util/Security.php
*/
namespace Friendica\Util;
use Friendica\BaseObject;
use Friendica\Database\DBA;
use Friendica\Model\Contact;
use Friendica\Model\Group;
use Friendica\Core\L10n;
use Friendica\Model\PermissionSet;
use Friendica\Core\System;
/**
* Secures that User is allow to do requests
*/
class Security extends BaseObject
{
public static function can_write_wall($owner)
{
static $verified = 0;
if (!local_user() && !remote_user()) {
return false;
}
$uid = local_user();
if ($uid == $owner) {
return true;
}
if (local_user() && ($owner == 0)) {
return true;
}
if (remote_user()) {
// use remembered decision and avoid a DB lookup for each and every display item
// DO NOT use this function if there are going to be multiple owners
// We have a contact-id for an authenticated remote user, this block determines if the contact
// belongs to this page owner, and has the necessary permissions to post content
if ($verified === 2) {
return true;
} elseif ($verified === 1) {
return false;
} else {
$cid = 0;
if (!empty($_SESSION['remote'])) {
foreach ($_SESSION['remote'] as $visitor) {
if ($visitor['uid'] == $owner) {
$cid = $visitor['cid'];
break;
}
}
}
if (!$cid) {
return false;
}
$r = q("SELECT `contact`.*, `user`.`page-flags` FROM `contact` INNER JOIN `user` on `user`.`uid` = `contact`.`uid`
WHERE `contact`.`uid` = %d AND `contact`.`id` = %d AND `contact`.`blocked` = 0 AND `contact`.`pending` = 0
AND `user`.`blockwall` = 0 AND `readonly` = 0 AND ( `contact`.`rel` IN ( %d , %d ) OR `user`.`page-flags` = %d ) LIMIT 1",
intval($owner),
intval($cid),
intval(Contact::SHARING),
intval(Contact::FRIEND),
intval(Contact::PAGE_COMMUNITY)
);
if (DBA::isResult($r)) {
$verified = 2;
return true;
} else {
$verified = 1;
}
}
}
return false;
}
/// @TODO $groups should be array
public static function permissions_sql($owner_id, $remote_verified = false, $groups = null)
{
$local_user = local_user();
$remote_user = remote_user();
/**
* Construct permissions
*
* default permissions - anonymous user
*/
$sql = " AND allow_cid = ''
AND allow_gid = ''
AND deny_cid = ''
AND deny_gid = ''
";
/**
* Profile owner - everything is visible
*/
if ($local_user && $local_user == $owner_id) {
$sql = '';
/**
* Authenticated visitor. Unless pre-verified,
* check that the contact belongs to this $owner_id
* and load the groups the visitor belongs to.
* If pre-verified, the caller is expected to have already
* done this and passed the groups into this function.
*/
} elseif ($remote_user) {
/*
* Authenticated visitor. Unless pre-verified,
* check that the contact belongs to this $owner_id
* and load the groups the visitor belongs to.
* If pre-verified, the caller is expected to have already
* done this and passed the groups into this function.
*/
if (!$remote_verified) {
if (DBA::exists('contact', ['id' => $remote_user, 'uid' => $owner_id, 'blocked' => false])) {
$remote_verified = true;
$groups = Group::getIdsByContactId($remote_user);
}
}
if ($remote_verified) {
$gs = '<<>>'; // should be impossible to match
if (is_array($groups)) {
foreach ($groups as $g) {
$gs .= '|<' . intval($g) . '>';
}
}
$sql = sprintf(
" AND ( NOT (deny_cid REGEXP '<%d>' OR deny_gid REGEXP '%s')
AND ( allow_cid REGEXP '<%d>' OR allow_gid REGEXP '%s' OR ( allow_cid = '' AND allow_gid = '') )
)
",
intval($remote_user),
DBA::escape($gs),
intval($remote_user),
DBA::escape($gs)
);
}
}
return $sql;
}
public static function item_permissions_sql($owner_id, $remote_verified = false, $groups = null)
{
$local_user = local_user();
$remote_user = remote_user();
/*
* Construct permissions
*
* default permissions - anonymous user
*/
$sql = " AND NOT `item`.`private`";
// Profile owner - everything is visible
if ($local_user && ($local_user == $owner_id)) {
$sql = '';
} elseif ($remote_user) {
/*
* Authenticated visitor. Unless pre-verified,
* check that the contact belongs to this $owner_id
* and load the groups the visitor belongs to.
* If pre-verified, the caller is expected to have already
* done this and passed the groups into this function.
*/
$set = PermissionSet::get($owner_id, $remote_user, $groups);
if (!empty($set)) {
$sql_set = " OR (`item`.`private` IN (1,2) AND `item`.`wall` AND `item`.`psid` IN (" . implode(',', $set) . "))";
} else {
$sql_set = '';
}
$sql = " AND (NOT `item`.`private`" . $sql_set . ")";
}
return $sql;
}
/*
* Functions used to protect against Cross-Site Request Forgery
* The security token has to base on at least one value that an attacker can't know - here it's the session ID and the private key.
* In this implementation, a security token is reusable (if the user submits a form, goes back and resubmits the form, maybe with small changes;
* or if the security token is used for ajax-calls that happen several times), but only valid for a certain amout of time (3hours).
* The "typename" seperates the security tokens of different types of forms. This could be relevant in the following case:
* A security token is used to protekt a link from CSRF (e.g. the "delete this profile"-link).
* If the new page contains by any chance external elements, then the used security token is exposed by the referrer.
* Actually, important actions should not be triggered by Links / GET-Requests at all, but somethimes they still are,
* so this mechanism brings in some damage control (the attacker would be able to forge a request to a form of this type, but not to forms of other types).
*/
public static function get_form_security_token($typename = '')
{
$a = get_app();
$timestamp = time();
$sec_hash = hash('whirlpool', $a->user['guid'] . $a->user['prvkey'] . session_id() . $timestamp . $typename);
return $timestamp . '.' . $sec_hash;
}
public static function check_form_security_token($typename = '', $formname = 'form_security_token')
{
$hash = null;
if (!empty($_REQUEST[$formname])) {
/// @TODO Careful, not secured!
$hash = $_REQUEST[$formname];
}
if (!empty($_SERVER['HTTP_X_CSRF_TOKEN'])) {
/// @TODO Careful, not secured!
$hash = $_SERVER['HTTP_X_CSRF_TOKEN'];
}
if (empty($hash)) {
return false;
}
$max_livetime = 10800; // 3 hours
$a = get_app();
$x = explode('.', $hash);
if (time() > (IntVal($x[0]) + $max_livetime)) {
return false;
}
$sec_hash = hash('whirlpool', $a->user['guid'] . $a->user['prvkey'] . session_id() . $x[0] . $typename);
return ($sec_hash == $x[1]);
}
private static function check_form_security_std_err_msg()
{
return L10n::t("The form security token was not correct. This probably happened because the form has been opened for too long \x28>3 hours\x29 before submitting it.") . EOL;
}
public static function check_form_security_token_redirectOnErr($err_redirect, $typename = '', $formname = 'form_security_token')
{
if (!check_form_security_token($typename, $formname)) {
$a = get_app();
logger('check_form_security_token failed: user ' . $a->user['guid'] . ' - form element ' . $typename);
logger('check_form_security_token failed: _REQUEST data: ' . print_r($_REQUEST, true), LOGGER_DATA);
notice(check_form_security_std_err_msg());
goaway(System::baseUrl() . $err_redirect);
}
}
public static function check_form_security_token_ForbiddenOnErr($typename = '', $formname = 'form_security_token')
{
if (!check_form_security_token($typename, $formname)) {
$a = get_app();
logger('check_form_security_token failed: user ' . $a->user['guid'] . ' - form element ' . $typename);
logger('check_form_security_token failed: _REQUEST data: ' . print_r($_REQUEST, true), LOGGER_DATA);
header('HTTP/1.1 403 Forbidden');
killme();
}
}
}
?>