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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* ClamAV antivirus integration.
*
* @package antivirus_clamav
* @copyright 2015 Ruslan Kabalin, Lancaster University.
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace antivirus_clamav;
defined('MOODLE_INTERNAL') || die();
/** Default socket timeout */
define('ANTIVIRUS_CLAMAV_SOCKET_TIMEOUT', 10);
/** Default socket data stream chunk size (32Mb: 32 * 1024 * 1024) */
define('ANTIVIRUS_CLAMAV_SOCKET_CHUNKSIZE', 33554432);
/**
* Class implementing ClamAV antivirus.
* @copyright 2015 Ruslan Kabalin, Lancaster University.
* @copyright 2019 Didier Raboud, Liip AG.
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class scanner extends \core\antivirus\scanner {
/**
* Are the necessary antivirus settings configured?
*
* @return bool True if all necessary config settings been entered
*/
public function is_configured() {
if ($this->get_config('runningmethod') === 'commandline') {
return (bool)$this->get_config('pathtoclam');
} else if ($this->get_config('runningmethod') === 'unixsocket') {
return (bool)$this->get_config('pathtounixsocket');
} else if ($this->get_config('runningmethod') === 'tcpsocket') {
return (bool)$this->get_config('tcpsockethost') && (bool)$this->get_config('tcpsocketport');
}
return false;
}
/**
* Scan file.
*
* This method is normally called from antivirus manager (\core\antivirus\manager::scan_file).
*
* @param string $file Full path to the file.
* @param string $filename Name of the file (could be different from physical file if temp file is used).
* @return int Scanning result constant.
*/
public function scan_file($file, $filename) {
if (!is_readable($file)) {
// This should not happen.
debugging('File is not readable.');
return self::SCAN_RESULT_ERROR;
}
// We can do direct stream scanning if unixsocket or tcpsocket running methods are in use,
// if not, use default process.
$maxtries = get_config('antivirus_clamav', 'tries');
$tries = 0;
do {
$runningmethod = $this->get_config('runningmethod');
$tries++;
switch ($runningmethod) {
case 'unixsocket':
case 'tcpsocket':
$return = $this->scan_file_execute_socket($file, $runningmethod);
break;
case 'commandline':
$return = $this->scan_file_execute_commandline($file);
break;
default:
// This should not happen.
throw new \coding_exception('Unknown running method.');
}
} while ($return == self::SCAN_RESULT_ERROR && $tries < $maxtries);
$notice = get_string('tries_notice', 'antivirus_clamav',
['tries' => $tries, 'notice' => $this->get_scanning_notice()]);
$this->set_scanning_notice($notice);
if ($return === self::SCAN_RESULT_ERROR) {
$this->message_admins($this->get_scanning_notice());
// If plugin settings require us to act like virus on any error,
// return SCAN_RESULT_FOUND result.
if ($this->get_config('clamfailureonupload') === 'actlikevirus') {
return self::SCAN_RESULT_FOUND;
} else if ($this->get_config('clamfailureonupload') === 'tryagain') {
// Do not upload the file, just give a message to the user to try again later.
unlink($file);
throw new \core\antivirus\scanner_exception('antivirusfailed', '', ['item' => $filename],
null, 'antivirus_clamav');
}
}
return $return;
}
/**
* Scan data.
*
* @param string $data The variable containing the data to scan.
* @return int Scanning result constant.
*/
public function scan_data($data) {
// We can do direct stream scanning if unixsocket or tcpsocket running methods are in use,
// if not, use default process.
$runningmethod = $this->get_config('runningmethod');
if (in_array($runningmethod, array('unixsocket', 'tcpsocket'))) {
$return = $this->scan_data_execute_socket($data, $runningmethod);
if ($return === self::SCAN_RESULT_ERROR) {
$this->message_admins($this->get_scanning_notice());
// If plugin settings require us to act like virus on any error,
// return SCAN_RESULT_FOUND result.
if ($this->get_config('clamfailureonupload') === 'actlikevirus') {
return self::SCAN_RESULT_FOUND;
}
}
return $return;
} else {
return parent::scan_data($data);
}
}
/**
* Returns a Unix domain socket destination url
*
* @return string The socket url, fit for stream_socket_client()
*/
private function get_unixsocket_destination() {
return 'unix://' . $this->get_config('pathtounixsocket');
}
/**
* Returns a Internet domain socket destination url
*
* @return string The socket url, fit for stream_socket_client()
*/
private function get_tcpsocket_destination() {
return 'tcp://' . $this->get_config('tcpsockethost') . ':' . $this->get_config('tcpsocketport');
}
/**
* Returns the string equivalent of a numeric clam error code
*
* @param int $returncode The numeric error code in question.
* @return string The definition of the error code
*/
private function get_clam_error_code($returncode) {
$returncodes = array();
$returncodes[0] = 'No virus found.';
$returncodes[1] = 'Virus(es) found.';
$returncodes[2] = ' An error occured'; // Specific to clamdscan.
// All after here are specific to clamscan.
$returncodes[40] = 'Unknown option passed.';
$returncodes[50] = 'Database initialization error.';
$returncodes[52] = 'Not supported file type.';
$returncodes[53] = 'Can\'t open directory.';
$returncodes[54] = 'Can\'t open file. (ofm)';
$returncodes[55] = 'Error reading file. (ofm)';
$returncodes[56] = 'Can\'t stat input file / directory.';
$returncodes[57] = 'Can\'t get absolute path name of current working directory.';
$returncodes[58] = 'I/O error, please check your filesystem.';
$returncodes[59] = 'Can\'t get information about current user from /etc/passwd.';
$returncodes[60] = 'Can\'t get information about user \'clamav\' (default name) from /etc/passwd.';
$returncodes[61] = 'Can\'t fork.';
$returncodes[63] = 'Can\'t create temporary files/directories (check permissions).';
$returncodes[64] = 'Can\'t write to temporary directory (please specify another one).';
$returncodes[70] = 'Can\'t allocate and clear memory (calloc).';
$returncodes[71] = 'Can\'t allocate memory (malloc).';
if (isset($returncodes[$returncode])) {
return $returncodes[$returncode];
}
return get_string('unknownerror', 'antivirus_clamav');
}
/**
* Scan file using command line utility.
*
* @param string $file Full path to the file.
* @return int Scanning result constant.
*/
public function scan_file_execute_commandline($file) {
$pathtoclam = trim($this->get_config('pathtoclam'));
if (!file_exists($pathtoclam) or !is_executable($pathtoclam)) {
// Misconfigured clam, notify admins.
$notice = get_string('invalidpathtoclam', 'antivirus_clamav', $pathtoclam);
$this->set_scanning_notice($notice);
return self::SCAN_RESULT_ERROR;
}
$clamparam = ' --stdout ';
// If we are dealing with clamdscan, clamd is likely run as a different user
// that might not have permissions to access your file.
// To make clamdscan work, we use --fdpass parameter that passes the file
// descriptor permissions to clamd, which allows it to scan given file
// irrespective of directory and file permissions.
if (basename($pathtoclam) == 'clamdscan') {
$clamparam .= '--fdpass ';
}
// Execute scan.
$cmd = escapeshellcmd($pathtoclam).$clamparam.escapeshellarg($file);
exec($cmd, $output, $return);
// Return variable will contain execution return code. It will be 0 if no virus is found,
// 1 if virus is found, and 2 or above for the error. Return codes 0 and 1 correspond to
// SCAN_RESULT_OK and SCAN_RESULT_FOUND constants, so we return them as it is.
// If there is an error, it gets stored as scanning notice and function
// returns SCAN_RESULT_ERROR.
if ($return > self::SCAN_RESULT_FOUND) {
$notice = get_string('clamfailed', 'antivirus_clamav', $this->get_clam_error_code($return));
$notice .= "\n\n". implode("\n", $output);
$this->set_scanning_notice($notice);
return self::SCAN_RESULT_ERROR;
}
return (int)$return;
}
/**
* Scan file using sockets.
*
* @param string $file Full path to the file.
* @param string $type Either 'tcpsocket' or 'unixsocket'
* @return int Scanning result constant.
*/
public function scan_file_execute_socket($file, $type) {
switch ($type) {
case "tcpsocket":
$socketurl = $this->get_tcpsocket_destination();
break;
case "unixsocket":
$socketurl = $this->get_unixsocket_destination();
break;
default;
// This should not happen.
debugging('Unknown socket type.');
return self::SCAN_RESULT_ERROR;
}
$socket = stream_socket_client($socketurl,
$errno, $errstr, ANTIVIRUS_CLAMAV_SOCKET_TIMEOUT);
if (!$socket) {
// Can't open socket for some reason, notify admins.
$notice = get_string('errorcantopensocket', 'antivirus_clamav', "$errstr ($errno)");
$this->set_scanning_notice($notice);
return self::SCAN_RESULT_ERROR;
} else {
if ($type == "unixsocket") {
// Execute scanning. We are running SCAN command and passing file as an argument,
// it is the fastest option, but clamav user need to be able to access it, so
// we give group read permissions first and assume 'clamav' user is in web server
// group (in Debian the default webserver group is 'www-data').
// Using 'n' as command prefix is forcing clamav to only treat \n as newline delimeter,
// this is to avoid unexpected newline characters on different systems.
$perms = fileperms($file);
chmod($file, 0640);
// Actual scan.
fwrite($socket, "nSCAN ".$file."\n");
// Get ClamAV answer.
$output = stream_get_line($socket, 4096);
// After scanning we revert permissions to initial ones.
chmod($file, $perms);
} else if ($type == "tcpsocket") {
// Execute scanning by passing the entire file through the TCP socket.
// This is not fast, but is the only possibility over a network.
// Using 'n' as command prefix is forcing clamav to only treat \n as newline delimeter,
// this is to avoid unexpected newline characters on different systems.
// Actual scan.
fwrite($socket, "nINSTREAM\n");
// Open the file for reading.
$fhandle = fopen($file, 'rb');
while (!feof($fhandle)) {
// Read it by chunks; write them to the TCP socket.
$chunk = fread($fhandle, ANTIVIRUS_CLAMAV_SOCKET_CHUNKSIZE);
$size = pack('N', strlen($chunk));
fwrite($socket, $size);
fwrite($socket, $chunk);
}
// Terminate streaming.
fwrite($socket, pack('N', 0));
// Get ClamAV answer.
$output = stream_get_line($socket, 4096);
fclose($fhandle);
}
// Free up the ClamAV socket.
fclose($socket);
// Parse the output.
return $this->parse_socket_response($output);
}
}
/**
* Scan data socket.
*
* We are running INSTREAM command and passing data stream in chunks.
* The format of the chunk is: <length><data> where <length> is the size of the following
* data in bytes expressed as a 4 byte unsigned integer in network byte order and <data>
* is the actual chunk. Streaming is terminated by sending a zero-length chunk.
* Do not exceed StreamMaxLength as defined in clamd.conf, otherwise clamd will
* reply with INSTREAM size limit exceeded and close the connection.
*
* @param string $data The variable containing the data to scan.
* @param string $type Either 'tcpsocket' or 'unixsocket'
* @return int Scanning result constant.
*/
public function scan_data_execute_socket($data, $type) {
switch ($type) {
case "tcpsocket":
$socketurl = $this->get_tcpsocket_destination();
break;
case "unixsocket":
$socketurl = $this->get_unixsocket_destination();
break;
default;
// This should not happen.
debugging('Unknown socket type!');
return self::SCAN_RESULT_ERROR;
}
$socket = stream_socket_client($socketurl, $errno, $errstr, ANTIVIRUS_CLAMAV_SOCKET_TIMEOUT);
if (!$socket) {
// Can't open socket for some reason, notify admins.
$notice = get_string('errorcantopensocket', 'antivirus_clamav', "$errstr ($errno)");
$this->set_scanning_notice($notice);
return self::SCAN_RESULT_ERROR;
} else {
// Initiate data stream scanning.
// Using 'n' as command prefix is forcing clamav to only treat \n as newline delimeter,
// this is to avoid unexpected newline characters on different systems.
fwrite($socket, "nINSTREAM\n");
// Send data in chunks of ANTIVIRUS_CLAMAV_SOCKET_CHUNKSIZE size.
while (strlen($data) > 0) {
$chunk = substr($data, 0, ANTIVIRUS_CLAMAV_SOCKET_CHUNKSIZE);
$data = substr($data, ANTIVIRUS_CLAMAV_SOCKET_CHUNKSIZE);
$size = pack('N', strlen($chunk));
fwrite($socket, $size);
fwrite($socket, $chunk);
}
// Terminate streaming.
fwrite($socket, pack('N', 0));
$output = stream_get_line($socket, 4096);
fclose($socket);
// Parse the output.
return $this->parse_socket_response($output);
}
}
/**
* Parse socket command response.
*
* @param string $output The socket response.
* @return int Scanning result constant.
*/
private function parse_socket_response($output) {
$splitoutput = explode(': ', $output);
$message = trim($splitoutput[1]);
if ($message === 'OK') {
return self::SCAN_RESULT_OK;
} else {
$parts = explode(' ', $message);
$status = array_pop($parts);
if ($status === 'FOUND') {
return self::SCAN_RESULT_FOUND;
} else {
$notice = get_string('clamfailed', 'antivirus_clamav', $this->get_clam_error_code(2));
$notice .= "\n\n" . $output;
$this->set_scanning_notice($notice);
return self::SCAN_RESULT_ERROR;
}
}
}
/**
* Scan data using Unix domain socket.
*
* @deprecated since Moodle 3.9 MDL-64075 - please do not use this function any more.
* @see antivirus_clamav\scanner::scan_data_execute_socket()
*
* @param string $data The variable containing the data to scan.
* @return int Scanning result constant.
*/
public function scan_data_execute_unixsocket($data) {
debugging('antivirus_clamav\scanner::scan_data_execute_unixsocket() is deprecated. ' .
'Use antivirus_clamav\scanner::scan_data_execute_socket() instead.', DEBUG_DEVELOPER);
return $this->scan_data_execute_socket($data, "unixsocket");
}
/**
* Scan file using Unix domain socket.
*
* @deprecated since Moodle 3.9 MDL-64075 - please do not use this function any more.
* @see antivirus_clamav\scanner::scan_file_execute_socket()
*
* @param string $file Full path to the file.
* @return int Scanning result constant.
*/
public function scan_file_execute_unixsocket($file) {
debugging('antivirus_clamav\scanner::scan_file_execute_unixsocket() is deprecated. ' .
'Use antivirus_clamav\scanner::scan_file_execute_socket() instead.', DEBUG_DEVELOPER);
return $this->scan_file_execute_socket($file, "unixsocket");
}
}