diff options
Diffstat (limited to 'paramiko/transport.py')
| -rw-r--r-- | paramiko/transport.py | 169 |
1 files changed, 139 insertions, 30 deletions
diff --git a/paramiko/transport.py b/paramiko/transport.py index 1ee73cdb..78102e76 100644 --- a/paramiko/transport.py +++ b/paramiko/transport.py @@ -26,7 +26,7 @@ import sys import threading import time import weakref -from hashlib import md5, sha1 +from hashlib import md5, sha1, sha256, sha512 from cryptography.hazmat.backends import default_backend from cryptography.hazmat.primitives.ciphers import algorithms, Cipher, modes @@ -50,7 +50,7 @@ from paramiko.common import xffffffff, cMSG_CHANNEL_OPEN, cMSG_IGNORE, \ 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 @@ -95,11 +95,39 @@ class Transport (threading.Thread, ClosingContextManager): _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-group14-sha1', 'diffie-hellman-group-exchange-sha1' , 'diffie-hellman-group1-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 = { @@ -109,10 +137,22 @@ class Transport (threading.Thread, ClosingContextManager): 'block-size': 16, 'key-size': 16 }, + 'aes192-ctr': { + 'class': algorithms.AES, + 'mode': modes.CTR, + 'block-size': 16, + 'key-size': 24 + }, 'aes256-ctr': { 'class': algorithms.AES, 'mode': modes.CTR, 'block-size': 16, + 'key-size': 16 + }, + 'aes256-ctr': { + 'class': AES, + 'mode': AES.MODE_CTR, + 'block-size': 16, 'key-size': 32 }, 'blowfish-cbc': { @@ -127,6 +167,12 @@ class Transport (threading.Thread, ClosingContextManager): 'block-size': 16, 'key-size': 16 }, + 'aes192-cbc': { + 'class': algorithms.AES, + 'mode': modes.CBC, + 'block-size': 16, + 'key-size': 24 + }, 'aes256-cbc': { 'class': algorithms.AES, 'mode': modes.CBC, @@ -157,6 +203,8 @@ class Transport (threading.Thread, ClosingContextManager): _mac_info = { '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}, } @@ -171,6 +219,7 @@ class Transport (threading.Thread, ClosingContextManager): '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 @@ -337,6 +386,8 @@ class Transport (threading.Thread, ClosingContextManager): 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 @@ -629,7 +680,7 @@ class Transport (threading.Thread, ClosingContextManager): """ return self.active - def open_session(self, window_size=None, max_packet_size=None): + 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 @@ -654,7 +705,8 @@ class Transport (threading.Thread, ClosingContextManager): """ return self.open_channel('session', window_size=window_size, - max_packet_size=max_packet_size) + max_packet_size=max_packet_size, + timeout=timeout) def open_x11_channel(self, src_addr=None): """ @@ -701,7 +753,8 @@ class Transport (threading.Thread, ClosingContextManager): dest_addr=None, src_addr=None, window_size=None, - max_packet_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 @@ -725,17 +778,20 @@ class Transport (threading.Thread, ClosingContextManager): 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) @@ -764,6 +820,7 @@ class Transport (threading.Thread, ClosingContextManager): finally: self.lock.release() self._send_user_message(m) + start_ts = time.time() while True: event.wait(0.1) if not self.active: @@ -773,6 +830,8 @@ class Transport (threading.Thread, ClosingContextManager): raise e 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 @@ -1539,13 +1598,23 @@ class Transport (threading.Thread, ClosingContextManager): m.add_bytes(self.H) m.add_byte(b(id)) m.add_bytes(self.session_id) - out = sofar = sha1(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 = sha1(m.asbytes()).digest() + digest = hash_algo(m.asbytes()).digest() out += digest sofar += digest return out[:nbytes] @@ -1635,7 +1704,16 @@ class Transport (threading.Thread, ClosingContextManager): 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) @@ -1685,6 +1763,7 @@ class Transport (threading.Thread, ClosingContextManager): 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()) @@ -1733,6 +1812,18 @@ class Transport (threading.Thread, ClosingContextManager): 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): @@ -1770,6 +1861,7 @@ class Transport (threading.Thread, ClosingContextManager): 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(' ') @@ -1798,10 +1890,12 @@ class Transport (threading.Thread, ClosingContextManager): 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)) @@ -1853,15 +1947,24 @@ class Transport (threading.Thread, ClosingContextManager): ' 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__, @@ -1889,7 +1992,9 @@ class Transport (threading.Thread, ClosingContextManager): 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)) @@ -1901,6 +2006,9 @@ class Transport (threading.Thread, ClosingContextManager): 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)) @@ -1912,10 +2020,11 @@ class Transport (threading.Thread, ClosingContextManager): 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 @@ -1936,8 +2045,8 @@ class Transport (threading.Thread, ClosingContextManager): engine = self._get_cipher(self.remote_cipher, key_in, IV_in, self._DECRYPT) 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) else: @@ -1963,8 +2072,8 @@ class Transport (threading.Thread, ClosingContextManager): engine = self._get_cipher(self.local_cipher, key_out, IV_out, self._ENCRYPT) 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) else: |