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Constant time for wp_verify_nonce(). 

Merges [29382] to the 3.9 branch.

Adds a second copy of hash_equals() to pluggable.php in case compat.php is not copied over in an update. (The general goal is no cross-file dependencies for minor releases.)

Built from https://develop.svn.wordpress.org/branches/3.9@29384


git-svn-id: http://core.svn.wordpress.org/branches/3.9@29162 1a063a9b-81f0-0310-95a4-ce76da25c4cd
This commit is contained in:
Andrew Nacin 2014-08-06 05:42:16 +00:00
parent 7d2bc0ab0d
commit c4b546f41f
2 changed files with 70 additions and 3 deletions
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29
wp-includes/compat.php
View File

@ -94,3 +94,32 @@ if ( !function_exists('json_decode') ) {
return is_array($data) ? array_map(__FUNCTION__, $data) : $data;
}
}
if ( ! function_exists( 'hash_equals' ) ) :
/**
* Compare two strings in constant time.
*
* This function was added in PHP 5.6.
* It can leak the length of a string.
*
* @since 3.9.2
*
* @param string $a Expected string.
* @param string $b Actual string.
* @return bool Whether strings are equal.
*/
function hash_equals( $a, $b ) {
$a_length = strlen( $a );
if ( $a_length !== strlen( $b ) ) {
return false;
}
$result = 0;
// Do not attempt to "optimize" this.
for ( $i = 0; $i < $a_length; $i++ ) {
$result |= ord( $a[ $i ] ) ^ ord( $b[ $i ] );
}
return $result === 0;
}
endif;

44
wp-includes/pluggable.php
View File

@ -647,7 +647,7 @@ function wp_validate_auth_cookie($cookie = '', $scheme = '') {
$key = wp_hash($username . $pass_frag . '|' . $expiration, $scheme);
$hash = hash_hmac('md5', $username . '|' . $expiration, $key);
if ( hash_hmac( 'md5', $hmac, $key ) !== hash_hmac( 'md5', $hash, $key ) ) {
if ( ! hash_equals( $hash, $hmac ) ) {
/**
* Fires if a bad authentication cookie hash is encountered.
*
@ -1658,11 +1658,17 @@ function wp_verify_nonce($nonce, $action = -1) {
$i = wp_nonce_tick();
// Nonce generated 0-12 hours ago
if ( substr(wp_hash($i . $action . $uid, 'nonce'), -12, 10) === $nonce )
$expected = substr( wp_hash( $i . '|' . $action . '|' . $uid . '|' . $token, 'nonce'), -12, 10 );
if ( hash_equals( $expected, $nonce ) ) {
return 1;
}
// Nonce generated 12-24 hours ago
if ( substr(wp_hash(($i - 1) . $action . $uid, 'nonce'), -12, 10) === $nonce )
$expected = substr( wp_hash( ( $i - 1 ) . '|' . $action . '|' . $uid . '|' . $token, 'nonce' ), -12, 10 );
if ( hash_equals( $expected, $nonce ) ) {
return 2;
}
// Invalid nonce
return false;
}
@ -2200,3 +2206,35 @@ function wp_text_diff( $left_string, $right_string, $args = null ) {
}
endif;
if ( ! function_exists( 'hash_equals' ) ) :
/**
* Compare two strings in constant time.
*
* This function is NOT pluggable. It is in this file (in addition to
* compat.php) to prevent errors if, during an update, pluggable.php
* copies over but compat.php does not.
*
* This function was added in PHP 5.6.
* It can leak the length of a string.
*
* @since 3.9.2
*
* @param string $a Expected string.
* @param string $b Actual string.
* @return bool Whether strings are equal.
*/
function hash_equals( $a, $b ) {
$a_length = strlen( $a );
if ( $a_length !== strlen( $b ) ) {
return false;
}
$result = 0;
// Do not attempt to "optimize" this.
for ( $i = 0; $i < $a_length; $i++ ) {
$result |= ord( $a[ $i ] ) ^ ord( $b[ $i ] );
}
return $result === 0;
}
endif;