diff options
Diffstat (limited to 'include/security.php')
| -rwxr-xr-x | include/security.php | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/include/security.php b/include/security.php index 8c536b656..19e91eb63 100755 --- a/include/security.php +++ b/include/security.php @@ -288,3 +288,59 @@ function item_permissions_sql($owner_id,$remote_verified = false,$groups = null) } +/* + * Functions used to protect against Cross-Site Request Forgery + * The security token has to base on at least one value that an attacker can't know - here it's the session ID and the private key. + * In this implementation, a security token is reusable (if the user submits a form, goes back and resubmits the form, maybe with small changes; + * or if the security token is used for ajax-calls that happen several times), but only valid for a certain amout of time (3hours). + * The "typename" seperates the security tokens of different types of forms. This could be relevant in the following case: + * A security token is used to protekt a link from CSRF (e.g. the "delete this profile"-link). + * If the new page contains by any chance external elements, then the used security token is exposed by the referrer. + * Actually, important actions should not be triggered by Links / GET-Requests at all, but somethimes they still are, + * so this mechanism brings in some damage control (the attacker would be able to forge a request to a form of this type, but not to forms of other types). + */ +function get_form_security_token($typename = '') { + $a = get_app(); + + $timestamp = time(); + $sec_hash = hash('whirlpool', $a->user['guid'] . $a->user['prvkey'] . session_id() . $timestamp . $typename); + + return $timestamp . '.' . $sec_hash; +} + +function check_form_security_token($typename = '', $formname = 'form_security_token') { + if (!x($_REQUEST, $formname)) return false; + $hash = $_REQUEST[$formname]; + + $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 == $x[1]); +} + +function check_form_security_std_err_msg() { + return t('The form security token was not correct. This probably happened because the form has been opened for too long (>3 hours) before subitting it.') . EOL; +} +function check_form_security_token_redirectOnErr($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($a->get_baseurl() . $err_redirect ); + } +} +function check_form_security_token_ForbiddenOnErr($typename = '', $formname = 'form_security_token') { + if (!check_form_security_token($typename, $formname)) { + 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(); + } +}
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