Git-Center/System/SSH/Agent.php
2015-08-13 15:21:19 +02:00

461 lines
13 KiB
PHP

<?php
/**
* Pure-PHP ssh-agent client.
*
* PHP versions 4 and 5
*
* Here are some examples of how to use this library:
* <code>
* <?php
* include 'System/SSH/Agent.php';
* include 'Net/SSH2.php';
*
* $agent = new System_SSH_Agent();
*
* $ssh = new Net_SSH2('www.domain.tld');
* if (!$ssh->login('username', $agent)) {
* exit('Login Failed');
* }
*
* echo $ssh->exec('pwd');
* echo $ssh->exec('ls -la');
* ?>
* </code>
*
* LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* @category System
* @package System_SSH_Agent
* @author Jim Wigginton <terrafrost@php.net>
* @copyright 2014 Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
* @internal See http://api.libssh.org/rfc/PROTOCOL.agent
*/
/**#@+
* Message numbers
*
* @access private
*/
// to request SSH1 keys you have to use SSH_AGENTC_REQUEST_RSA_IDENTITIES (1)
define('SYSTEM_SSH_AGENTC_REQUEST_IDENTITIES', 11);
// this is the SSH2 response; the SSH1 response is SSH_AGENT_RSA_IDENTITIES_ANSWER (2).
define('SYSTEM_SSH_AGENT_IDENTITIES_ANSWER', 12);
define('SYSTEM_SSH_AGENT_FAILURE', 5);
// the SSH1 request is SSH_AGENTC_RSA_CHALLENGE (3)
define('SYSTEM_SSH_AGENTC_SIGN_REQUEST', 13);
// the SSH1 response is SSH_AGENT_RSA_RESPONSE (4)
define('SYSTEM_SSH_AGENT_SIGN_RESPONSE', 14);
/**@+
* Agent forwarding status
*
* @access private
*/
// no forwarding requested and not active
define('SYSTEM_SSH_AGENT_FORWARD_NONE', 0);
// request agent forwarding when opportune
define('SYSTEM_SSH_AGENT_FORWARD_REQUEST', 1);
// forwarding has been request and is active
define('SYSTEM_SSH_AGENT_FORWARD_ACTIVE', 2);
/**#@-*/
/**
* Pure-PHP ssh-agent client identity object
*
* Instantiation should only be performed by System_SSH_Agent class.
* This could be thought of as implementing an interface that Crypt_RSA
* implements. ie. maybe a Net_SSH_Auth_PublicKey interface or something.
* The methods in this interface would be getPublicKey, setSignatureMode
* and sign since those are the methods phpseclib looks for to perform
* public key authentication.
*
* @package System_SSH_Agent
* @author Jim Wigginton <terrafrost@php.net>
* @access internal
*/
class System_SSH_Agent_Identity
{
/**
* Key Object
*
* @var Crypt_RSA
* @access private
* @see System_SSH_Agent_Identity::getPublicKey()
*/
var $key;
/**
* Key Blob
*
* @var String
* @access private
* @see System_SSH_Agent_Identity::sign()
*/
var $key_blob;
/**
* Socket Resource
*
* @var Resource
* @access private
* @see System_SSH_Agent_Identity::sign()
*/
var $fsock;
/**
* Default Constructor.
*
* @param Resource $fsock
* @return System_SSH_Agent_Identity
* @access private
*/
function System_SSH_Agent_Identity($fsock)
{
$this->fsock = $fsock;
}
/**
* Set Public Key
*
* Called by System_SSH_Agent::requestIdentities()
*
* @param Crypt_RSA $key
* @access private
*/
function setPublicKey($key)
{
$this->key = $key;
$this->key->setPublicKey();
}
/**
* Set Public Key
*
* Called by System_SSH_Agent::requestIdentities(). The key blob could be extracted from $this->key
* but this saves a small amount of computation.
*
* @param String $key_blob
* @access private
*/
function setPublicKeyBlob($key_blob)
{
$this->key_blob = $key_blob;
}
/**
* Get Public Key
*
* Wrapper for $this->key->getPublicKey()
*
* @param Integer $format optional
* @return Mixed
* @access public
*/
function getPublicKey($format = null)
{
return !isset($format) ? $this->key->getPublicKey() : $this->key->getPublicKey($format);
}
/**
* Set Signature Mode
*
* Doesn't do anything as ssh-agent doesn't let you pick and choose the signature mode. ie.
* ssh-agent's only supported mode is CRYPT_RSA_SIGNATURE_PKCS1
*
* @param Integer $mode
* @access public
*/
function setSignatureMode($mode)
{
}
/**
* Create a signature
*
* See "2.6.2 Protocol 2 private key signature request"
*
* @param String $message
* @return String
* @access public
*/
function sign($message)
{
// the last parameter (currently 0) is for flags and ssh-agent only defines one flag (for ssh-dss): SSH_AGENT_OLD_SIGNATURE
$packet = pack('CNa*Na*N', SYSTEM_SSH_AGENTC_SIGN_REQUEST, strlen($this->key_blob), $this->key_blob, strlen($message), $message, 0);
$packet = pack('Na*', strlen($packet), $packet);
if (strlen($packet) != fputs($this->fsock, $packet)) {
user_error('Connection closed during signing');
}
$length = current(unpack('N', fread($this->fsock, 4)));
$type = ord(fread($this->fsock, 1));
if ($type != SYSTEM_SSH_AGENT_SIGN_RESPONSE) {
user_error('Unable to retreive signature');
}
$signature_blob = fread($this->fsock, $length - 1);
// the only other signature format defined - ssh-dss - is the same length as ssh-rsa
// the + 12 is for the other various SSH added length fields
return substr($signature_blob, strlen('ssh-rsa') + 12);
}
}
/**
* Pure-PHP ssh-agent client identity factory
*
* requestIdentities() method pumps out System_SSH_Agent_Identity objects
*
* @package System_SSH_Agent
* @author Jim Wigginton <terrafrost@php.net>
* @access internal
*/
class System_SSH_Agent
{
/**
* Socket Resource
*
* @var Resource
* @access private
*/
var $fsock;
/**
* Agent forwarding status
*
* @access private
*/
var $forward_status = SYSTEM_SSH_AGENT_FORWARD_NONE;
/**
* Buffer for accumulating forwarded authentication
* agent data arriving on SSH data channel destined
* for agent unix socket
*
* @access private
*/
var $socket_buffer = '';
/**
* Tracking the number of bytes we are expecting
* to arrive for the agent socket on the SSH data
* channel
*/
var $expected_bytes = 0;
/**
* Default Constructor
*
* @return System_SSH_Agent
* @access public
*/
function System_SSH_Agent()
{
switch (true) {
case isset($_SERVER['SSH_AUTH_SOCK']):
$address = $_SERVER['SSH_AUTH_SOCK'];
break;
case isset($_ENV['SSH_AUTH_SOCK']):
$address = $_ENV['SSH_AUTH_SOCK'];
break;
default:
user_error('SSH_AUTH_SOCK not found');
return false;
}
$this->fsock = fsockopen('unix://' . $address, 0, $errno, $errstr);
if (!$this->fsock) {
user_error("Unable to connect to ssh-agent (Error $errno: $errstr)");
}
}
/**
* Request Identities
*
* See "2.5.2 Requesting a list of protocol 2 keys"
* Returns an array containing zero or more System_SSH_Agent_Identity objects
*
* @return Array
* @access public
*/
function requestIdentities()
{
if (!$this->fsock) {
return array();
}
$packet = pack('NC', 1, SYSTEM_SSH_AGENTC_REQUEST_IDENTITIES);
if (strlen($packet) != fputs($this->fsock, $packet)) {
user_error('Connection closed while requesting identities');
}
$length = current(unpack('N', fread($this->fsock, 4)));
$type = ord(fread($this->fsock, 1));
if ($type != SYSTEM_SSH_AGENT_IDENTITIES_ANSWER) {
user_error('Unable to request identities');
}
$identities = array();
$keyCount = current(unpack('N', fread($this->fsock, 4)));
for ($i = 0; $i < $keyCount; $i++) {
$length = current(unpack('N', fread($this->fsock, 4)));
$key_blob = fread($this->fsock, $length);
$length = current(unpack('N', fread($this->fsock, 4)));
$key_comment = fread($this->fsock, $length);
$length = current(unpack('N', substr($key_blob, 0, 4)));
$key_type = substr($key_blob, 4, $length);
switch ($key_type) {
case 'ssh-rsa':
if (!class_exists('Crypt_RSA')) {
include_once 'Crypt/RSA.php';
}
$key = new Crypt_RSA();
$key->loadKey('ssh-rsa ' . base64_encode($key_blob) . ' ' . $key_comment);
break;
case 'ssh-dss':
// not currently supported
break;
}
// resources are passed by reference by default
if (isset($key)) {
$identity = new System_SSH_Agent_Identity($this->fsock);
$identity->setPublicKey($key);
$identity->setPublicKeyBlob($key_blob);
$identities[] = $identity;
unset($key);
}
}
return $identities;
}
/**
* Signal that agent forwarding should
* be requested when a channel is opened
*
* @param Net_SSH2 $ssh
* @return Boolean
* @access public
*/
function startSSHForwarding($ssh)
{
if ($this->forward_status == SYSTEM_SSH_AGENT_FORWARD_NONE) {
$this->forward_status = SYSTEM_SSH_AGENT_FORWARD_REQUEST;
}
}
/**
* Request agent forwarding of remote server
*
* @param Net_SSH2 $ssh
* @return Boolean
* @access private
*/
function _request_forwarding($ssh)
{
$request_channel = $ssh->_get_open_channel();
if ($request_channel === false) {
return false;
}
$packet = pack(
'CNNa*C',
NET_SSH2_MSG_CHANNEL_REQUEST,
$ssh->server_channels[$request_channel],
strlen('auth-agent-req@openssh.com'),
'auth-agent-req@openssh.com',
1
);
$ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_REQUEST;
if (!$ssh->_send_binary_packet($packet)) {
return false;
}
$response = $ssh->_get_channel_packet($request_channel);
if ($response === false) {
return false;
}
$ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_OPEN;
$this->forward_status = SYSTEM_SSH_AGENT_FORWARD_ACTIVE;
return true;
}
/**
* On successful channel open
*
* This method is called upon successful channel
* open to give the SSH Agent an opportunity
* to take further action. i.e. request agent forwarding
*
* @param Net_SSH2 $ssh
* @access private
*/
function _on_channel_open($ssh)
{
if ($this->forward_status == SYSTEM_SSH_AGENT_FORWARD_REQUEST) {
$this->_request_forwarding($ssh);
}
}
/**
* Forward data to SSH Agent and return data reply
*
* @param String $data
* @return data from SSH Agent
* @access private
*/
function _forward_data($data)
{
if ($this->expected_bytes > 0) {
$this->socket_buffer.= $data;
$this->expected_bytes -= strlen($data);
} else {
$agent_data_bytes = current(unpack('N', $data));
$current_data_bytes = strlen($data);
$this->socket_buffer = $data;
if ($current_data_bytes != $agent_data_bytes + 4) {
$this->expected_bytes = ($agent_data_bytes + 4) - $current_data_bytes;
return false;
}
}
if (strlen($this->socket_buffer) != fwrite($this->fsock, $this->socket_buffer)) {
user_error('Connection closed attempting to forward data to SSH agent');
}
$this->socket_buffer = '';
$this->expected_bytes = 0;
$agent_reply_bytes = current(unpack('N', fread($this->fsock, 4)));
$agent_reply_data = fread($this->fsock, $agent_reply_bytes);
$agent_reply_data = current(unpack('a*', $agent_reply_data));
return pack('Na*', $agent_reply_bytes, $agent_reply_data);
}
}