diff options
Diffstat (limited to 'paramiko/transport.py')
| -rw-r--r-- | paramiko/transport.py | 579 |
1 files changed, 457 insertions, 122 deletions
diff --git a/paramiko/transport.py b/paramiko/transport.py index cbbdb79f..18fb103b 100644 --- a/paramiko/transport.py +++ b/paramiko/transport.py @@ -20,17 +20,21 @@ Core protocol implementation """ +from __future__ import print_function +import os import socket import sys import threading import time import weakref +from hashlib import md5, sha1, sha256, sha512 import paramiko from paramiko import util from paramiko.auth_handler import AuthHandler +from paramiko.ssh_gss import GSSAuth from paramiko.channel import Channel -from paramiko.common import rng, xffffffff, cMSG_CHANNEL_OPEN, cMSG_IGNORE, \ +from paramiko.common import xffffffff, cMSG_CHANNEL_OPEN, cMSG_IGNORE, \ cMSG_GLOBAL_REQUEST, DEBUG, MSG_KEXINIT, MSG_IGNORE, MSG_DISCONNECT, \ MSG_DEBUG, ERROR, WARNING, cMSG_UNIMPLEMENTED, INFO, cMSG_KEXINIT, \ cMSG_NEWKEYS, MSG_NEWKEYS, cMSG_REQUEST_SUCCESS, cMSG_REQUEST_FAILURE, \ @@ -40,11 +44,14 @@ from paramiko.common import rng, xffffffff, cMSG_CHANNEL_OPEN, cMSG_IGNORE, \ MSG_CHANNEL_OPEN_SUCCESS, MSG_CHANNEL_OPEN_FAILURE, MSG_CHANNEL_OPEN, \ MSG_CHANNEL_SUCCESS, MSG_CHANNEL_FAILURE, MSG_CHANNEL_DATA, \ MSG_CHANNEL_EXTENDED_DATA, MSG_CHANNEL_WINDOW_ADJUST, MSG_CHANNEL_REQUEST, \ - MSG_CHANNEL_EOF, MSG_CHANNEL_CLOSE + MSG_CHANNEL_EOF, MSG_CHANNEL_CLOSE, MIN_WINDOW_SIZE, MIN_PACKET_SIZE, \ + MAX_WINDOW_SIZE, DEFAULT_WINDOW_SIZE, DEFAULT_MAX_PACKET_SIZE from paramiko.compress import ZlibCompressor, ZlibDecompressor from paramiko.dsskey import DSSKey -from paramiko.kex_gex import KexGex +from paramiko.kex_gex import KexGex, KexGexSHA256 from paramiko.kex_group1 import KexGroup1 +from paramiko.kex_group14 import KexGroup14 +from paramiko.kex_gss import KexGSSGex, KexGSSGroup1, KexGSSGroup14, NullHostKey from paramiko.message import Message from paramiko.packet import Packetizer, NeedRekeyException from paramiko.primes import ModulusPack @@ -55,11 +62,9 @@ from paramiko.server import ServerInterface from paramiko.sftp_client import SFTPClient from paramiko.ssh_exception import (SSHException, BadAuthenticationType, ChannelException, ProxyCommandFailure) -from paramiko.util import retry_on_signal +from paramiko.util import retry_on_signal, ClosingContextManager, clamp_value -from Crypto import Random from Crypto.Cipher import Blowfish, AES, DES3, ARC4 -from Crypto.Hash import SHA, MD5 try: from Crypto.Util import Counter except ImportError: @@ -77,40 +82,124 @@ import atexit atexit.register(_join_lingering_threads) -class Transport (threading.Thread): +class Transport (threading.Thread, ClosingContextManager): """ An SSH Transport attaches to a stream (usually a socket), negotiates an encrypted session, authenticates, and then creates stream tunnels, called `channels <.Channel>`, across the session. Multiple channels can be multiplexed across a single session (and often are, in the case of port forwardings). + + Instances of this class may be used as context managers. """ _PROTO_ID = '2.0' _CLIENT_ID = 'paramiko_%s' % paramiko.__version__ - _preferred_ciphers = ('aes128-ctr', 'aes256-ctr', 'aes128-cbc', 'blowfish-cbc', - 'aes256-cbc', '3des-cbc', 'arcfour128', 'arcfour256') - _preferred_macs = ('hmac-sha1', 'hmac-md5', 'hmac-sha1-96', 'hmac-md5-96') - _preferred_keys = ('ssh-rsa', 'ssh-dss', 'ecdsa-sha2-nistp256') - _preferred_kex = ('diffie-hellman-group1-sha1', 'diffie-hellman-group-exchange-sha1') + # These tuples of algorithm identifiers are in preference order; do not + # reorder without reason! + _preferred_ciphers = ( + 'aes128-ctr', + 'aes192-ctr', + 'aes256-ctr', + 'aes128-cbc', + 'blowfish-cbc', + 'aes192-cbc', + 'aes256-cbc', + '3des-cbc', + 'arcfour128', + 'arcfour256', + ) + _preferred_macs = ( + 'hmac-sha2-256', + 'hmac-sha2-512', + 'hmac-md5', + 'hmac-sha1-96', + 'hmac-md5-96', + 'hmac-sha1', + ) + _preferred_keys = ( + 'ssh-rsa', + 'ssh-dss', + 'ecdsa-sha2-nistp256', + ) + _preferred_kex = ( + 'diffie-hellman-group1-sha1', + 'diffie-hellman-group14-sha1', + 'diffie-hellman-group-exchange-sha1', + 'diffie-hellman-group-exchange-sha256', + ) _preferred_compression = ('none',) _cipher_info = { - 'aes128-ctr': {'class': AES, 'mode': AES.MODE_CTR, 'block-size': 16, 'key-size': 16}, - 'aes256-ctr': {'class': AES, 'mode': AES.MODE_CTR, 'block-size': 16, 'key-size': 32}, - 'blowfish-cbc': {'class': Blowfish, 'mode': Blowfish.MODE_CBC, 'block-size': 8, 'key-size': 16}, - 'aes128-cbc': {'class': AES, 'mode': AES.MODE_CBC, 'block-size': 16, 'key-size': 16}, - 'aes256-cbc': {'class': AES, 'mode': AES.MODE_CBC, 'block-size': 16, 'key-size': 32}, - '3des-cbc': {'class': DES3, 'mode': DES3.MODE_CBC, 'block-size': 8, 'key-size': 24}, - 'arcfour128': {'class': ARC4, 'mode': None, 'block-size': 8, 'key-size': 16}, - 'arcfour256': {'class': ARC4, 'mode': None, 'block-size': 8, 'key-size': 32}, + 'aes128-ctr': { + 'class': AES, + 'mode': AES.MODE_CTR, + 'block-size': 16, + 'key-size': 16 + }, + 'aes192-ctr': { + 'class': AES, + 'mode': AES.MODE_CTR, + 'block-size': 16, + 'key-size': 24 + }, + 'aes256-ctr': { + 'class': AES, + 'mode': AES.MODE_CTR, + 'block-size': 16, + 'key-size': 32 + }, + 'blowfish-cbc': { + 'class': Blowfish, + 'mode': Blowfish.MODE_CBC, + 'block-size': 8, + 'key-size': 16 + }, + 'aes128-cbc': { + 'class': AES, + 'mode': AES.MODE_CBC, + 'block-size': 16, + 'key-size': 16 + }, + 'aes192-cbc': { + 'class': AES, + 'mode': AES.MODE_CBC, + 'block-size': 16, + 'key-size': 24 + }, + 'aes256-cbc': { + 'class': AES, + 'mode': AES.MODE_CBC, + 'block-size': 16, + 'key-size': 32 + }, + '3des-cbc': { + 'class': DES3, + 'mode': DES3.MODE_CBC, + 'block-size': 8, + 'key-size': 24 + }, + 'arcfour128': { + 'class': ARC4, + 'mode': None, + 'block-size': 8, + 'key-size': 16 + }, + 'arcfour256': { + 'class': ARC4, + 'mode': None, + 'block-size': 8, + 'key-size': 32 + }, } _mac_info = { - 'hmac-sha1': {'class': SHA, 'size': 20}, - 'hmac-sha1-96': {'class': SHA, 'size': 12}, - 'hmac-md5': {'class': MD5, 'size': 16}, - 'hmac-md5-96': {'class': MD5, 'size': 12}, + 'hmac-sha1': {'class': sha1, 'size': 20}, + 'hmac-sha1-96': {'class': sha1, 'size': 12}, + 'hmac-sha2-256': {'class': sha256, 'size': 32}, + 'hmac-sha2-512': {'class': sha512, 'size': 64}, + 'hmac-md5': {'class': md5, 'size': 16}, + 'hmac-md5-96': {'class': md5, 'size': 12}, } _key_info = { @@ -121,7 +210,12 @@ class Transport (threading.Thread): _kex_info = { 'diffie-hellman-group1-sha1': KexGroup1, + 'diffie-hellman-group14-sha1': KexGroup14, 'diffie-hellman-group-exchange-sha1': KexGex, + 'diffie-hellman-group-exchange-sha256': KexGexSHA256, + 'gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==': KexGSSGroup1, + 'gss-group14-sha1-toWM5Slw5Ew8Mqkay+al2g==': KexGSSGroup14, + 'gss-gex-sha1-toWM5Slw5Ew8Mqkay+al2g==': KexGSSGex } _compression_info = { @@ -135,7 +229,12 @@ class Transport (threading.Thread): _modulus_pack = None - def __init__(self, sock): + def __init__(self, + sock, + default_window_size=DEFAULT_WINDOW_SIZE, + default_max_packet_size=DEFAULT_MAX_PACKET_SIZE, + gss_kex=False, + gss_deleg_creds=True): """ Create a new SSH session over an existing socket, or socket-like object. This only creates the `.Transport` object; it doesn't begin the @@ -161,8 +260,24 @@ class Transport (threading.Thread): address and used for communication. Exceptions from the ``socket`` call may be thrown in this case. + .. note:: + Modifying the the window and packet sizes might have adverse + effects on your channels created from this transport. The default + values are the same as in the OpenSSH code base and have been + battle tested. + :param socket sock: a socket or socket-like object to create the session over. + :param int default_window_size: + sets the default window size on the transport. (defaults to + 2097152) + :param int default_max_packet_size: + sets the default max packet size on the transport. (defaults to + 32768) + + .. versionchanged:: 1.15 + Added the ``default_window_size`` and ``default_max_packet_size`` + arguments. """ self.active = False @@ -194,7 +309,6 @@ class Transport (threading.Thread): # okay, normal socket-ish flow here... threading.Thread.__init__(self) self.setDaemon(True) - self.rng = rng self.sock = sock # Python < 2.3 doesn't have the settimeout method - RogerB try: @@ -217,6 +331,21 @@ class Transport (threading.Thread): self.host_key_type = None self.host_key = None + # GSS-API / SSPI Key Exchange + self.use_gss_kex = gss_kex + # This will be set to True if GSS-API Key Exchange was performed + self.gss_kex_used = False + self.kexgss_ctxt = None + self.gss_host = None + if self.use_gss_kex: + self.kexgss_ctxt = GSSAuth("gssapi-keyex", gss_deleg_creds) + self._preferred_kex = ('gss-gex-sha1-toWM5Slw5Ew8Mqkay+al2g==', + 'gss-group14-sha1-toWM5Slw5Ew8Mqkay+al2g==', + 'gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==', + 'diffie-hellman-group-exchange-sha1', + 'diffie-hellman-group14-sha1', + 'diffie-hellman-group1-sha1') + # state used during negotiation self.kex_engine = None self.H = None @@ -233,8 +362,8 @@ class Transport (threading.Thread): self.channel_events = {} # (id -> Event) self.channels_seen = {} # (id -> True) self._channel_counter = 0 - self.window_size = 65536 - self.max_packet_size = 34816 + self.default_max_packet_size = default_max_packet_size + self.default_window_size = default_window_size self._forward_agent_handler = None self._x11_handler = None self._tcp_handler = None @@ -250,6 +379,8 @@ class Transport (threading.Thread): self.global_response = None # response Message from an arbitrary global request self.completion_event = None # user-defined event callbacks self.banner_timeout = 15 # how long (seconds) to wait for the SSH banner + self.handshake_timeout = 15 # how long (seconds) to wait for the handshake to finish after SSH banner sent. + # server mode: self.server_mode = False @@ -289,6 +420,7 @@ class Transport (threading.Thread): .. versionadded:: 1.5.3 """ + self.sock.close() self.close() def get_security_options(self): @@ -300,6 +432,17 @@ class Transport (threading.Thread): """ return SecurityOptions(self) + def set_gss_host(self, gss_host): + """ + Setter for C{gss_host} if GSS-API Key Exchange is performed. + + :param str gss_host: The targets name in the kerberos database + Default: The name of the host to connect to + :rtype: Void + """ + # We need the FQDN to get this working with SSPI + self.gss_host = socket.getfqdn(gss_host) + def start_client(self, event=None): """ Negotiate a new SSH2 session as a client. This is the first step after @@ -320,9 +463,10 @@ class Transport (threading.Thread): .. note:: `connect` is a simpler method for connecting as a client. - .. note:: After calling this method (or `start_server` or `connect`), - you should no longer directly read from or write to the original - socket object. + .. note:: + After calling this method (or `start_server` or `connect`), you + should no longer directly read from or write to the original socket + object. :param .threading.Event event: an event to trigger when negotiation is complete (optional) @@ -340,7 +484,6 @@ class Transport (threading.Thread): # synchronous, wait for a result self.completion_event = event = threading.Event() self.start() - Random.atfork() while True: event.wait(0.1) if not self.active: @@ -348,7 +491,7 @@ class Transport (threading.Thread): if e is not None: raise e raise SSHException('Negotiation failed.') - if event.isSet(): + if event.is_set(): break def start_server(self, event=None, server=None): @@ -413,7 +556,7 @@ class Transport (threading.Thread): if e is not None: raise e raise SSHException('Negotiation failed.') - if event.isSet(): + if event.is_set(): break def add_server_key(self, key): @@ -451,6 +594,7 @@ class Transport (threading.Thread): pass return None + @staticmethod def load_server_moduli(filename=None): """ (optional) @@ -476,7 +620,7 @@ class Transport (threading.Thread): .. note:: This has no effect when used in client mode. """ - Transport._modulus_pack = ModulusPack(rng) + Transport._modulus_pack = ModulusPack() # places to look for the openssh "moduli" file file_list = ['/etc/ssh/moduli', '/usr/local/etc/moduli'] if filename is not None: @@ -490,7 +634,6 @@ class Transport (threading.Thread): # none succeeded Transport._modulus_pack = None return False - load_server_moduli = staticmethod(load_server_moduli) def close(self): """ @@ -530,18 +673,33 @@ class Transport (threading.Thread): """ return self.active - def open_session(self): + def open_session(self, window_size=None, max_packet_size=None, timeout=None): """ Request a new channel to the server, of type ``"session"``. This is just an alias for calling `open_channel` with an argument of ``"session"``. + .. note:: Modifying the the window and packet sizes might have adverse + effects on the session created. The default values are the same + as in the OpenSSH code base and have been battle tested. + + :param int window_size: + optional window size for this session. + :param int max_packet_size: + optional max packet size for this session. + :return: a new `.Channel` :raises SSHException: if the request is rejected or the session ends prematurely + + .. versionchanged:: 1.15 + Added the ``window_size`` and ``max_packet_size`` arguments. """ - return self.open_channel('session') + return self.open_channel('session', + window_size=window_size, + max_packet_size=max_packet_size, + timeout=timeout) def open_x11_channel(self, src_addr=None): """ @@ -583,13 +741,23 @@ class Transport (threading.Thread): """ return self.open_channel('forwarded-tcpip', dest_addr, src_addr) - def open_channel(self, kind, dest_addr=None, src_addr=None): + def open_channel(self, + kind, + dest_addr=None, + src_addr=None, + window_size=None, + max_packet_size=None, + timeout=None): """ Request a new channel to the server. `Channels <.Channel>` are socket-like objects used for the actual transfer of data across the session. You may only request a channel after negotiating encryption (using `connect` or `start_client`) and authenticating. + .. note:: Modifying the the window and packet sizes might have adverse + effects on the channel created. The default values are the same + as in the OpenSSH code base and have been battle tested. + :param str kind: the kind of channel requested (usually ``"session"``, ``"forwarded-tcpip"``, ``"direct-tcpip"``, or ``"x11"``) @@ -599,22 +767,35 @@ class Transport (threading.Thread): ``"direct-tcpip"`` (ignored for other channel types) :param src_addr: the source address of this port forwarding, if ``kind`` is ``"forwarded-tcpip"``, ``"direct-tcpip"``, or ``"x11"`` + :param int window_size: + optional window size for this session. + :param int max_packet_size: + optional max packet size for this session. + :param float timeout: + optional timeout opening a channel, default 3600s (1h) + :return: a new `.Channel` on success - :raises SSHException: if the request is rejected or the session ends - prematurely + :raises SSHException: if the request is rejected, the session ends + prematurely or there is a timeout openning a channel + + .. versionchanged:: 1.15 + Added the ``window_size`` and ``max_packet_size`` arguments. """ if not self.active: raise SSHException('SSH session not active') + timeout = 3600 if timeout is None else timeout self.lock.acquire() try: + window_size = self._sanitize_window_size(window_size) + max_packet_size = self._sanitize_packet_size(max_packet_size) chanid = self._next_channel() m = Message() m.add_byte(cMSG_CHANNEL_OPEN) m.add_string(kind) m.add_int(chanid) - m.add_int(self.window_size) - m.add_int(self.max_packet_size) + m.add_int(window_size) + m.add_int(max_packet_size) if (kind == 'forwarded-tcpip') or (kind == 'direct-tcpip'): m.add_string(dest_addr[0]) m.add_int(dest_addr[1]) @@ -628,10 +809,11 @@ class Transport (threading.Thread): self.channel_events[chanid] = event = threading.Event() self.channels_seen[chanid] = True chan._set_transport(self) - chan._set_window(self.window_size, self.max_packet_size) + chan._set_window(window_size, max_packet_size) finally: self.lock.release() self._send_user_message(m) + start_ts = time.time() while True: event.wait(0.1) if not self.active: @@ -639,8 +821,10 @@ class Transport (threading.Thread): if e is None: e = SSHException('Unable to open channel.') raise e - if event.isSet(): + if event.is_set(): break + elif start_ts + timeout < time.time(): + raise SSHException('Timeout openning channel.') chan = self._channels.get(chanid) if chan is not None: return chan @@ -672,6 +856,7 @@ class Transport (threading.Thread): :param callable handler: optional handler for incoming forwarded connections, of the form ``func(Channel, (str, int), (str, int))``. + :return: the port number (`int`) allocated by the server :raises SSHException: if the server refused the TCP forward request @@ -733,8 +918,8 @@ class Transport (threading.Thread): m = Message() m.add_byte(cMSG_IGNORE) if byte_count is None: - byte_count = (byte_ord(rng.read(1)) % 32) + 10 - m.add_bytes(rng.read(byte_count)) + byte_count = (byte_ord(os.urandom(1)) % 32) + 10 + m.add_bytes(os.urandom(byte_count)) self._send_user_message(m) def renegotiate_keys(self): @@ -758,7 +943,7 @@ class Transport (threading.Thread): if e is not None: raise e raise SSHException('Negotiation failed.') - if self.completion_event.isSet(): + if self.completion_event.is_set(): break return @@ -809,7 +994,7 @@ class Transport (threading.Thread): self.completion_event.wait(0.1) if not self.active: return None - if self.completion_event.isSet(): + if self.completion_event.is_set(): break return self.global_response @@ -838,7 +1023,8 @@ class Transport (threading.Thread): self.lock.release() return chan - def connect(self, hostkey=None, username='', password=None, pkey=None): + def connect(self, hostkey=None, username='', password=None, pkey=None, + gss_host=None, gss_auth=False, gss_kex=False, gss_deleg_creds=True): """ Negotiate an SSH2 session, and optionally verify the server's host key and authenticate using a password or private key. This is a shortcut @@ -868,6 +1054,14 @@ class Transport (threading.Thread): :param .PKey pkey: a private key to use for authentication, if you want to use private key authentication; otherwise ``None``. + :param str gss_host: + The target's name in the kerberos database. Default: hostname + :param bool gss_auth: + ``True`` if you want to use GSS-API authentication. + :param bool gss_kex: + Perform GSS-API Key Exchange and user authentication. + :param bool gss_deleg_creds: + Whether to delegate GSS-API client credentials. :raises SSHException: if the SSH2 negotiation fails, the host key supplied by the server is incorrect, or authentication fails. @@ -878,7 +1072,9 @@ class Transport (threading.Thread): self.start_client() # check host key if we were given one - if hostkey is not None: + # If GSS-API Key Exchange was performed, we are not required to check + # the host key. + if (hostkey is not None) and not gss_kex: key = self.get_remote_server_key() if (key.get_name() != hostkey.get_name()) or (key.asbytes() != hostkey.asbytes()): self._log(DEBUG, 'Bad host key from server') @@ -887,13 +1083,19 @@ class Transport (threading.Thread): raise SSHException('Bad host key from server') self._log(DEBUG, 'Host key verified (%s)' % hostkey.get_name()) - if (pkey is not None) or (password is not None): - if password is not None: - self._log(DEBUG, 'Attempting password auth...') - self.auth_password(username, password) - else: + if (pkey is not None) or (password is not None) or gss_auth or gss_kex: + if gss_auth: + self._log(DEBUG, 'Attempting GSS-API auth... (gssapi-with-mic)') + self.auth_gssapi_with_mic(username, gss_host, gss_deleg_creds) + elif gss_kex: + self._log(DEBUG, 'Attempting GSS-API auth... (gssapi-keyex)') + self.auth_gssapi_keyex(username) + elif pkey is not None: self._log(DEBUG, 'Attempting public-key auth...') self.auth_publickey(username, pkey) + else: + self._log(DEBUG, 'Attempting password auth...') + self.auth_password(username, password) return @@ -1176,6 +1378,76 @@ class Transport (threading.Thread): self.auth_handler.auth_interactive(username, handler, my_event, submethods) return self.auth_handler.wait_for_response(my_event) + def auth_interactive_dumb(self, username, handler=None, submethods=''): + """ + Autenticate to the server interactively but dumber. + Just print the prompt and / or instructions to stdout and send back + the response. This is good for situations where partial auth is + achieved by key and then the user has to enter a 2fac token. + """ + + if not handler: + def handler(title, instructions, prompt_list): + answers = [] + if title: + print(title.strip()) + if instructions: + print(instructions.strip()) + for prompt,show_input in prompt_list: + print(prompt.strip(),end=' ') + answers.append(raw_input()) + return answers + return self.auth_interactive(username, handler, submethods) + + def auth_gssapi_with_mic(self, username, gss_host, gss_deleg_creds): + """ + Authenticate to the Server using GSS-API / SSPI. + + :param str username: The username to authenticate as + :param str gss_host: The target host + :param bool gss_deleg_creds: Delegate credentials or not + :return: list of auth types permissible for the next stage of + authentication (normally empty) + :rtype: list + :raise BadAuthenticationType: if gssapi-with-mic isn't + allowed by the server (and no event was passed in) + :raise AuthenticationException: if the authentication failed (and no + event was passed in) + :raise SSHException: if there was a network error + """ + if (not self.active) or (not self.initial_kex_done): + # we should never try to authenticate unless we're on a secure link + raise SSHException('No existing session') + my_event = threading.Event() + self.auth_handler = AuthHandler(self) + self.auth_handler.auth_gssapi_with_mic(username, gss_host, gss_deleg_creds, my_event) + return self.auth_handler.wait_for_response(my_event) + + def auth_gssapi_keyex(self, username): + """ + Authenticate to the Server with GSS-API / SSPI if GSS-API Key Exchange + was the used key exchange method. + + :param str username: The username to authenticate as + :param str gss_host: The target host + :param bool gss_deleg_creds: Delegate credentials or not + :return: list of auth types permissible for the next stage of + authentication (normally empty) + :rtype: list + :raise BadAuthenticationType: if GSS-API Key Exchange was not performed + (and no event was passed in) + :raise AuthenticationException: if the authentication failed (and no + event was passed in) + :raise SSHException: if there was a network error + """ + if (not self.active) or (not self.initial_kex_done): + # we should never try to authenticate unless we're on a secure link + raise SSHException('No existing session') + my_event = threading.Event() + self.auth_handler = AuthHandler(self) + self.auth_handler.auth_gssapi_keyex(username, my_event) + return self.auth_handler.wait_for_response(my_event) + def set_log_channel(self, name): """ Set the channel for this transport's logging. The default is @@ -1260,7 +1532,7 @@ class Transport (threading.Thread): def stop_thread(self): self.active = False self.packetizer.close() - while self.isAlive(): + while self.is_alive() and (self is not threading.current_thread()): self.join(10) ### internals... @@ -1304,7 +1576,7 @@ class Transport (threading.Thread): self._log(DEBUG, 'Dropping user packet because connection is dead.') return self.clear_to_send_lock.acquire() - if self.clear_to_send.isSet(): + if self.clear_to_send.is_set(): break self.clear_to_send_lock.release() if time.time() > start + self.clear_to_send_timeout: @@ -1340,13 +1612,23 @@ class Transport (threading.Thread): m.add_bytes(self.H) m.add_byte(b(id)) m.add_bytes(self.session_id) - out = sofar = SHA.new(m.asbytes()).digest() + # Fallback to SHA1 for kex engines that fail to specify a hex + # algorithm, or for e.g. transport tests that don't run kexinit. + hash_algo = getattr(self.kex_engine, 'hash_algo', None) + hash_select_msg = "kex engine %s specified hash_algo %r" % (self.kex_engine.__class__.__name__, hash_algo) + if hash_algo is None: + hash_algo = sha1 + hash_select_msg += ", falling back to sha1" + if not hasattr(self, '_logged_hash_selection'): + self._log(DEBUG, hash_select_msg) + setattr(self, '_logged_hash_selection', True) + out = sofar = hash_algo(m.asbytes()).digest() while len(out) < nbytes: m = Message() m.add_mpint(self.K) m.add_bytes(self.H) m.add_bytes(sofar) - digest = SHA.new(m.asbytes()).digest() + digest = hash_algo(m.asbytes()).digest() out += digest sofar += digest return out[:nbytes] @@ -1394,6 +1676,17 @@ class Transport (threading.Thread): finally: self.lock.release() + def _sanitize_window_size(self, window_size): + if window_size is None: + window_size = self.default_window_size + return clamp_value(MIN_WINDOW_SIZE, window_size, MAX_WINDOW_SIZE) + + def _sanitize_packet_size(self, max_packet_size): + if max_packet_size is None: + max_packet_size = self.default_max_packet_size + return clamp_value(MIN_PACKET_SIZE, max_packet_size, MAX_WINDOW_SIZE) + + def run(self): # (use the exposed "run" method, because if we specify a thread target # of a private method, threading.Thread will keep a reference to it @@ -1404,10 +1697,6 @@ class Transport (threading.Thread): # interpreter shutdown. self.sys = sys - # Required to prevent RNG errors when running inside many subprocess - # containers. - Random.atfork() - # active=True occurs before the thread is launched, to avoid a race _active_threads.append(self) if self.server_mode: @@ -1417,7 +1706,16 @@ class Transport (threading.Thread): try: try: self.packetizer.write_all(b(self.local_version + '\r\n')) + self._log(DEBUG, 'Local version/idstring: %s' % self.local_version) self._check_banner() + # The above is actually very much part of the handshake, but + # sometimes the banner can be read but the machine is not + # responding, for example when the remote ssh daemon is loaded + # in to memory but we can not read from the disk/spawn a new + # shell. + # Make sure we can specify a timeout for the initial handshake. + # Re-use the banner timeout for now. + self.packetizer.start_handshake(self.handshake_timeout) self._send_kex_init() self._expect_packet(MSG_KEXINIT) @@ -1442,7 +1740,7 @@ class Transport (threading.Thread): if ptype not in self._expected_packet: raise SSHException('Expecting packet from %r, got %d' % (self._expected_packet, ptype)) self._expected_packet = tuple() - if (ptype >= 30) and (ptype <= 39): + if (ptype >= 30) and (ptype <= 41): self.kex_engine.parse_next(ptype, m) continue @@ -1467,6 +1765,7 @@ class Transport (threading.Thread): msg.add_byte(cMSG_UNIMPLEMENTED) msg.add_int(m.seqno) self._send_message(msg) + self.packetizer.complete_handshake() except SSHException as e: self._log(ERROR, 'Exception: ' + str(e)) self._log(ERROR, util.tb_strings()) @@ -1515,6 +1814,18 @@ class Transport (threading.Thread): if self.sys.modules is not None: raise + + def _log_agreement(self, which, local, remote): + # Log useful, non-duplicative line re: an agreed-upon algorithm. + # Old code implied algorithms could be asymmetrical (different for + # inbound vs outbound) so we preserve that possibility. + msg = "{0} agreed: ".format(which) + if local == remote: + msg += local + else: + msg += "local={0}, remote={1}".format(local, remote) + self._log(DEBUG, msg) + ### protocol stages def _negotiate_keys(self, m): @@ -1552,6 +1863,7 @@ class Transport (threading.Thread): raise SSHException('Indecipherable protocol version "' + buf + '"') # save this server version string for later self.remote_version = buf + self._log(DEBUG, 'Remote version/idstring: %s' % buf) # pull off any attached comment comment = '' i = buf.find(' ') @@ -1580,10 +1892,12 @@ class Transport (threading.Thread): self.clear_to_send_lock.release() self.in_kex = True if self.server_mode: - if (self._modulus_pack is None) and ('diffie-hellman-group-exchange-sha1' in self._preferred_kex): + mp_required_prefix = 'diffie-hellman-group-exchange-sha' + kex_mp = [k for k in self._preferred_kex if k.startswith(mp_required_prefix)] + if (self._modulus_pack is None) and (len(kex_mp) > 0): # can't do group-exchange if we don't have a pack of potential primes - pkex = list(self.get_security_options().kex) - pkex.remove('diffie-hellman-group-exchange-sha1') + pkex = [k for k in self.get_security_options().kex + if not k.startswith(mp_required_prefix)] self.get_security_options().kex = pkex available_server_keys = list(filter(list(self.server_key_dict.keys()).__contains__, self._preferred_keys)) @@ -1592,7 +1906,7 @@ class Transport (threading.Thread): m = Message() m.add_byte(cMSG_KEXINIT) - m.add_bytes(rng.read(16)) + m.add_bytes(os.urandom(16)) m.add_list(self._preferred_kex) m.add_list(available_server_keys) m.add_list(self._preferred_ciphers) @@ -1635,15 +1949,24 @@ class Transport (threading.Thread): ' server lang:' + str(server_lang_list) + ' kex follows?' + str(kex_follows)) - # as a server, we pick the first item in the client's list that we support. - # as a client, we pick the first item in our list that the server supports. + # as a server, we pick the first item in the client's list that we + # support. + # as a client, we pick the first item in our list that the server + # supports. if self.server_mode: - agreed_kex = list(filter(self._preferred_kex.__contains__, kex_algo_list)) + agreed_kex = list(filter( + self._preferred_kex.__contains__, + kex_algo_list + )) else: - agreed_kex = list(filter(kex_algo_list.__contains__, self._preferred_kex)) + agreed_kex = list(filter( + kex_algo_list.__contains__, + self._preferred_kex + )) if len(agreed_kex) == 0: raise SSHException('Incompatible ssh peer (no acceptable kex algorithm)') self.kex_engine = self._kex_info[agreed_kex[0]](self) + self._log(DEBUG, "Kex agreed: %s" % agreed_kex[0]) if self.server_mode: available_server_keys = list(filter(list(self.server_key_dict.keys()).__contains__, @@ -1671,7 +1994,9 @@ class Transport (threading.Thread): raise SSHException('Incompatible ssh server (no acceptable ciphers)') self.local_cipher = agreed_local_ciphers[0] self.remote_cipher = agreed_remote_ciphers[0] - self._log(DEBUG, 'Ciphers agreed: local=%s, remote=%s' % (self.local_cipher, self.remote_cipher)) + self._log_agreement( + 'Cipher', local=self.local_cipher, remote=self.remote_cipher + ) if self.server_mode: agreed_remote_macs = list(filter(self._preferred_macs.__contains__, client_mac_algo_list)) @@ -1683,6 +2008,9 @@ class Transport (threading.Thread): raise SSHException('Incompatible ssh server (no acceptable macs)') self.local_mac = agreed_local_macs[0] self.remote_mac = agreed_remote_macs[0] + self._log_agreement( + 'MAC', local=self.local_mac, remote=self.remote_mac + ) if self.server_mode: agreed_remote_compression = list(filter(self._preferred_compression.__contains__, client_compress_algo_list)) @@ -1694,10 +2022,11 @@ class Transport (threading.Thread): raise SSHException('Incompatible ssh server (no acceptable compression) %r %r %r' % (agreed_local_compression, agreed_remote_compression, self._preferred_compression)) self.local_compression = agreed_local_compression[0] self.remote_compression = agreed_remote_compression[0] - - self._log(DEBUG, 'using kex %s; server key type %s; cipher: local %s, remote %s; mac: local %s, remote %s; compression: local %s, remote %s' % - (agreed_kex[0], self.host_key_type, self.local_cipher, self.remote_cipher, self.local_mac, - self.remote_mac, self.local_compression, self.remote_compression)) + self._log_agreement( + 'Compression', + local=self.local_compression, + remote=self.remote_compression + ) # save for computing hash later... # now wait! openssh has a bug (and others might too) where there are @@ -1718,12 +2047,12 @@ class Transport (threading.Thread): engine = self._get_cipher(self.remote_cipher, key_in, IV_in) mac_size = self._mac_info[self.remote_mac]['size'] mac_engine = self._mac_info[self.remote_mac]['class'] - # initial mac keys are done in the hash's natural size (not the potentially truncated - # transmission size) + # initial mac keys are done in the hash's natural size (not the + # potentially truncated transmission size) if self.server_mode: - mac_key = self._compute_key('E', mac_engine.digest_size) + mac_key = self._compute_key('E', mac_engine().digest_size) else: - mac_key = self._compute_key('F', mac_engine.digest_size) + mac_key = self._compute_key('F', mac_engine().digest_size) self.packetizer.set_inbound_cipher(engine, block_size, mac_engine, mac_size, mac_key) compress_in = self._compression_info[self.remote_compression][1] if (compress_in is not None) and ((self.remote_compression != 'zlib@openssh.com') or self.authenticated): @@ -1745,12 +2074,12 @@ class Transport (threading.Thread): engine = self._get_cipher(self.local_cipher, key_out, IV_out) mac_size = self._mac_info[self.local_mac]['size'] mac_engine = self._mac_info[self.local_mac]['class'] - # initial mac keys are done in the hash's natural size (not the potentially truncated - # transmission size) + # initial mac keys are done in the hash's natural size (not the + # potentially truncated transmission size) if self.server_mode: - mac_key = self._compute_key('F', mac_engine.digest_size) + mac_key = self._compute_key('F', mac_engine().digest_size) else: - mac_key = self._compute_key('E', mac_engine.digest_size) + mac_key = self._compute_key('E', mac_engine().digest_size) sdctr = self.local_cipher.endswith('-ctr') self.packetizer.set_outbound_cipher(engine, block_size, mac_engine, mac_size, mac_key, sdctr) compress_out = self._compression_info[self.local_compression][0] @@ -1862,7 +2191,7 @@ class Transport (threading.Thread): self.lock.acquire() try: chan._set_remote_channel(server_chanid, server_window_size, server_max_packet_size) - self._log(INFO, 'Secsh channel %d opened.' % chanid) + self._log(DEBUG, 'Secsh channel %d opened.' % chanid) if chanid in self.channel_events: self.channel_events[chanid].set() del self.channel_events[chanid] @@ -1876,7 +2205,7 @@ class Transport (threading.Thread): reason_str = m.get_text() lang = m.get_text() reason_text = CONNECTION_FAILED_CODE.get(reason, '(unknown code)') - self._log(INFO, 'Secsh channel %d open FAILED: %s: %s' % (chanid, reason_str, reason_text)) + self._log(ERROR, 'Secsh channel %d open FAILED: %s: %s' % (chanid, reason_str, reason_text)) self.lock.acquire() try: self.saved_exception = ChannelException(reason, reason_text) @@ -1961,7 +2290,7 @@ class Transport (threading.Thread): self._channels.put(my_chanid, chan) self.channels_seen[my_chanid] = True chan._set_transport(self) - chan._set_window(self.window_size, self.max_packet_size) + chan._set_window(self.default_window_size, self.default_max_packet_size) chan._set_remote_channel(chanid, initial_window_size, max_packet_size) finally: self.lock.release() @@ -1969,10 +2298,10 @@ class Transport (threading.Thread): m.add_byte(cMSG_CHANNEL_OPEN_SUCCESS) m.add_int(chanid) m.add_int(my_chanid) - m.add_int(self.window_size) - m.add_int(self.max_packet_size) + m.add_int(self.default_window_size) + m.add_int(self.default_max_packet_size) self._send_message(m) - self._log(INFO, 'Secsh channel %d (%s) opened.', my_chanid, kind) + self._log(DEBUG, 'Secsh channel %d (%s) opened.', my_chanid, kind) if kind == 'auth-agent@openssh.com': self._forward_agent_handler(chan) elif kind == 'x11': @@ -2045,21 +2374,6 @@ class SecurityOptions (object): """ return '<paramiko.SecurityOptions for %s>' % repr(self._transport) - def _get_ciphers(self): - return self._transport._preferred_ciphers - - def _get_digests(self): - return self._transport._preferred_macs - - def _get_key_types(self): - return self._transport._preferred_keys - - def _get_kex(self): - return self._transport._preferred_kex - - def _get_compression(self): - return self._transport._preferred_compression - def _set(self, name, orig, x): if type(x) is list: x = tuple(x) @@ -2071,30 +2385,51 @@ class SecurityOptions (object): raise ValueError('unknown cipher') setattr(self._transport, name, x) - def _set_ciphers(self, x): + @property + def ciphers(self): + """Symmetric encryption ciphers""" + return self._transport._preferred_ciphers + + @ciphers.setter + def ciphers(self, x): self._set('_preferred_ciphers', '_cipher_info', x) - def _set_digests(self, x): + @property + def digests(self): + """Digest (one-way hash) algorithms""" + return self._transport._preferred_macs + + @digests.setter + def digests(self, x): self._set('_preferred_macs', '_mac_info', x) - def _set_key_types(self, x): + @property + def key_types(self): + """Public-key algorithms""" + return self._transport._preferred_keys + + @key_types.setter + def key_types(self, x): self._set('_preferred_keys', '_key_info', x) - def _set_kex(self, x): + + @property + def kex(self): + """Key exchange algorithms""" + return self._transport._preferred_kex + + @kex.setter + def kex(self, x): self._set('_preferred_kex', '_kex_info', x) - def _set_compression(self, x): - self._set('_preferred_compression', '_compression_info', x) + @property + def compression(self): + """Compression algorithms""" + return self._transport._preferred_compression - ciphers = property(_get_ciphers, _set_ciphers, None, - "Symmetric encryption ciphers") - digests = property(_get_digests, _set_digests, None, - "Digest (one-way hash) algorithms") - key_types = property(_get_key_types, _set_key_types, None, - "Public-key algorithms") - kex = property(_get_kex, _set_kex, None, "Key exchange algorithms") - compression = property(_get_compression, _set_compression, None, - "Compression algorithms") + @compression.setter + def compression(self, x): + self._set('_preferred_compression', '_compression_info', x) class ChannelMap (object): |