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<?php
/**
* @author Ross Nicoll <jrn@jrn.me.uk>
*
* @copyright Copyright (c) 2015, ownCloud, Inc.
* @license AGPL-3.0
*
* This code is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License, version 3,
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
*/
namespace OC\Files\Storage;
/**
* Uses phpseclib's Net_SFTP class and the Net_SFTP_Stream stream wrapper to
* provide access to SFTP servers.
*/
class SFTP_Key extends \OC\Files\Storage\SFTP {
private $publicKey;
private $privateKey;
public function __construct($params) {
parent::__construct($params);
$this->publicKey = $params['public_key'];
$this->privateKey = $params['private_key'];
}
/**
* Returns the connection.
*
* @return \Net_SFTP connected client instance
* @throws \Exception when the connection failed
*/
public function getConnection() {
if (!is_null($this->client)) {
return $this->client;
}
$hostKeys = $this->readHostKeys();
$this->client = new \Net_SFTP($this->getHost());
// The SSH Host Key MUST be verified before login().
$currentHostKey = $this->client->getServerPublicHostKey();
if (array_key_exists($this->getHost(), $hostKeys)) {
if ($hostKeys[$this->getHost()] !== $currentHostKey) {
throw new \Exception('Host public key does not match known key');
}
} else {
$hostKeys[$this->getHost()] = $currentHostKey;
$this->writeHostKeys($hostKeys);
}
$key = $this->getPrivateKey();
if (is_null($key)) {
throw new \Exception('Secret key could not be loaded');
}
if (!$this->client->login($this->getUser(), $key)) {
throw new \Exception('Login failed');
}
return $this->client;
}
/**
* Returns the private key to be used for authentication to the remote server.
*
* @return \Crypt_RSA instance or null in case of a failure to load the key.
*/
private function getPrivateKey() {
$key = new \Crypt_RSA();
$key->setPassword(\OC::$server->getConfig()->getSystemValue('secret', ''));
if (!$key->loadKey($this->privateKey)) {
// Should this exception rather than return null?
return null;
}
return $key;
}
/**
* Throws an exception if the provided host name/address is invalid (cannot be resolved
* and is not an IPv4 address).
*
* @return true; never returns in case of a problem, this return value is used just to
* make unit tests happy.
*/
public function assertHostAddressValid($hostname) {
// TODO: Should handle IPv6 addresses too
if (!preg_match('/^\d+\.\d+\.\d+\.\d+$/', $hostname) && gethostbyname($hostname) === $hostname) {
// Hostname is not an IPv4 address and cannot be resolved via DNS
throw new \InvalidArgumentException('Cannot resolve hostname.');
}
return true;
}
/**
* Throws an exception if the provided port number is invalid (cannot be resolved
* and is not an IPv4 address).
*
* @return true; never returns in case of a problem, this return value is used just to
* make unit tests happy.
*/
public function assertPortNumberValid($port) {
if (!preg_match('/^\d+$/', $port)) {
throw new \InvalidArgumentException('Port number must be a number.');
}
if ($port < 0 || $port > 65535) {
throw new \InvalidArgumentException('Port number must be between 0 and 65535 inclusive.');
}
return true;
}
/**
* Replaces anything that's not an alphanumeric character or "." in a hostname
* with "_", to make it safe for use as part of a file name.
*/
protected function sanitizeHostName($name) {
return preg_replace('/[^\d\w\._]/', '_', $name);
}
/**
* Replaces anything that's not an alphanumeric character or "_" in a username
* with "_", to make it safe for use as part of a file name.
*/
protected function sanitizeUserName($name) {
return preg_replace('/[^\d\w_]/', '_', $name);
}
public function test() {
if (empty($this->getHost())) {
\OC::$server->getLogger()->warning('Hostname has not been specified');
return false;
}
if (empty($this->getUser())) {
\OC::$server->getLogger()->warning('Username has not been specified');
return false;
}
if (!isset($this->privateKey)) {
\OC::$server->getLogger()->warning('Private key was missing from the request');
return false;
}
// Sanity check the host
$hostParts = explode(':', $this->getHost());
try {
if (count($hostParts) == 1) {
$hostname = $hostParts[0];
$this->assertHostAddressValid($hostname);
} else if (count($hostParts) == 2) {
$hostname = $hostParts[0];
$this->assertHostAddressValid($hostname);
$this->assertPortNumberValid($hostParts[1]);
} else {
throw new \Exception('Host connection string is invalid.');
}
} catch(\Exception $e) {
\OC::$server->getLogger()->warning($e->getMessage());
return false;
}
// Validate the key
$key = $this->getPrivateKey();
if (is_null($key)) {
\OC::$server->getLogger()->warning('Secret key could not be loaded');
return false;
}
try {
if ($this->getConnection()->nlist() === false) {
return false;
}
} catch(\Exception $e) {
// We should be throwing a more specific error, so we're not just catching
// Exception here
\OC::$server->getLogger()->warning($e->getMessage());
return false;
}
// Save the key somewhere it can easily be extracted later
if (\OC::$server->getUserSession()->getUser()) {
$view = new \OC\Files\View('/'.\OC::$server->getUserSession()->getUser()->getUId().'/files_external/sftp_keys');
if (!$view->is_dir('')) {
if (!$view->mkdir('')) {
\OC::$server->getLogger()->warning('Could not create secret key directory.');
return false;
}
}
$key_filename = $this->sanitizeUserName($this->getUser()).'@'.$this->sanitizeHostName($hostname).'.pub';
$key_file = $view->fopen($key_filename, "w");
if ($key_file) {
fwrite($key_file, $this->publicKey);
fclose($key_file);
} else {
\OC::$server->getLogger()->warning('Could not write secret key file.');
}
}
return true;
}
}
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