diff options
Diffstat (limited to 'system/libraries/Email.php')
| -rw-r--r-- | system/libraries/Email.php | 54 |
1 files changed, 47 insertions, 7 deletions
diff --git a/system/libraries/Email.php b/system/libraries/Email.php index 4ab873586..e25015450 100644 --- a/system/libraries/Email.php +++ b/system/libraries/Email.php @@ -1843,6 +1843,33 @@ class CI_Email { // -------------------------------------------------------------------- /** + * Validate email for shell + * + * Applies stricter, shell-safe validation to email addresses. + * Introduced to prevent RCE via sendmail's -f option. + * + * @see https://github.com/bcit-ci/CodeIgniter/issues/4963 + * @see https://gist.github.com/Zenexer/40d02da5e07f151adeaeeaa11af9ab36 + * @license https://creativecommons.org/publicdomain/zero/1.0/ CC0 1.0, Public Domain + * + * Credits for the base concept go to Paul Buonopane <paul@namepros.com> + * + * @param string $email + * @return bool + */ + protected function _validate_email_for_shell(&$email) + { + if (function_exists('idn_to_ascii') && $atpos = strpos($email, '@')) + { + $email = self::substr($email, 0, ++$atpos).idn_to_ascii(self::substr($email, $atpos)); + } + + return (filter_var($email, FILTER_VALIDATE_EMAIL) === $email && preg_match('#\A[a-z0-9._+-]+@[a-z0-9.-]{1,253}\z#i', $email)); + } + + // -------------------------------------------------------------------- + + /** * Send using mail() * * @return bool @@ -1854,7 +1881,11 @@ class CI_Email { $this->_recipients = implode(', ', $this->_recipients); } - if ($this->_safe_mode === TRUE) + // _validate_email_for_shell() below accepts by reference, + // so this needs to be assigned to a variable + $from = $this->clean_email($this->_headers['Return-Path']); + + if ($this->_safe_mode === TRUE || ! $this->_validate_email_for_shell($from)) { return mail($this->_recipients, $this->_subject, $this->_finalbody, $this->_header_str); } @@ -1862,7 +1893,7 @@ class CI_Email { { // most documentation of sendmail using the "-f" flag lacks a space after it, however // we've encountered servers that seem to require it to be in place. - return mail($this->_recipients, $this->_subject, $this->_finalbody, $this->_header_str, '-f '.$this->clean_email($this->_headers['Return-Path'])); + return mail($this->_recipients, $this->_subject, $this->_finalbody, $this->_header_str, '-f '.$from); } } @@ -1875,13 +1906,22 @@ class CI_Email { */ protected function _send_with_sendmail() { + // _validate_email_for_shell() below accepts by reference, + // so this needs to be assigned to a variable + $from = $this->clean_email($this->_headers['From']); + if ($this->_validate_email_for_shell($from)) + { + $from = '-f '.$from; + } + else + { + $from = ''; + } + // is popen() enabled? - if ( ! function_usable('popen') - OR FALSE === ($fp = @popen( - $this->mailpath.' -oi -f '.escapeshellarg($this->clean_email($this->_headers['From'])).' -t' - , 'w')) - ) // server probably has popen disabled, so nothing we can do to get a verbose error. + if ( ! function_usable('popen') OR FALSE === ($fp = @popen($this->mailpath.' -oi '.$from.' -t', 'w'))) { + // server probably has popen disabled, so nothing we can do to get a verbose error. return FALSE; } |