/usr/lib/python2.7/dist-packages/paramiko/auth_handler.py is in python-paramiko 1.16.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#
# This file is part of paramiko.
#
# Paramiko is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# Paramiko 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
"""
`.AuthHandler`
"""
import weakref
from paramiko.common import cMSG_SERVICE_REQUEST, cMSG_DISCONNECT, \
DISCONNECT_SERVICE_NOT_AVAILABLE, DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE, \
cMSG_USERAUTH_REQUEST, cMSG_SERVICE_ACCEPT, DEBUG, AUTH_SUCCESSFUL, INFO, \
cMSG_USERAUTH_SUCCESS, cMSG_USERAUTH_FAILURE, AUTH_PARTIALLY_SUCCESSFUL, \
cMSG_USERAUTH_INFO_REQUEST, WARNING, AUTH_FAILED, cMSG_USERAUTH_PK_OK, \
cMSG_USERAUTH_INFO_RESPONSE, MSG_SERVICE_REQUEST, MSG_SERVICE_ACCEPT, \
MSG_USERAUTH_REQUEST, MSG_USERAUTH_SUCCESS, MSG_USERAUTH_FAILURE, \
MSG_USERAUTH_BANNER, MSG_USERAUTH_INFO_REQUEST, MSG_USERAUTH_INFO_RESPONSE, \
cMSG_USERAUTH_GSSAPI_RESPONSE, cMSG_USERAUTH_GSSAPI_TOKEN, \
cMSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, cMSG_USERAUTH_GSSAPI_ERROR, \
cMSG_USERAUTH_GSSAPI_ERRTOK, cMSG_USERAUTH_GSSAPI_MIC,\
MSG_USERAUTH_GSSAPI_RESPONSE, MSG_USERAUTH_GSSAPI_TOKEN, \
MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, MSG_USERAUTH_GSSAPI_ERROR, \
MSG_USERAUTH_GSSAPI_ERRTOK, MSG_USERAUTH_GSSAPI_MIC, MSG_NAMES
from paramiko.message import Message
from paramiko.py3compat import bytestring
from paramiko.ssh_exception import SSHException, AuthenticationException, \
BadAuthenticationType, PartialAuthentication
from paramiko.server import InteractiveQuery
from paramiko.ssh_gss import GSSAuth
class AuthHandler (object):
"""
Internal class to handle the mechanics of authentication.
"""
def __init__(self, transport):
self.transport = weakref.proxy(transport)
self.username = None
self.authenticated = False
self.auth_event = None
self.auth_method = ''
self.banner = None
self.password = None
self.private_key = None
self.interactive_handler = None
self.submethods = None
# for server mode:
self.auth_username = None
self.auth_fail_count = 0
# for GSSAPI
self.gss_host = None
self.gss_deleg_creds = True
def is_authenticated(self):
return self.authenticated
def get_username(self):
if self.transport.server_mode:
return self.auth_username
else:
return self.username
def auth_none(self, username, event):
self.transport.lock.acquire()
try:
self.auth_event = event
self.auth_method = 'none'
self.username = username
self._request_auth()
finally:
self.transport.lock.release()
def auth_publickey(self, username, key, event):
self.transport.lock.acquire()
try:
self.auth_event = event
self.auth_method = 'publickey'
self.username = username
self.private_key = key
self._request_auth()
finally:
self.transport.lock.release()
def auth_password(self, username, password, event):
self.transport.lock.acquire()
try:
self.auth_event = event
self.auth_method = 'password'
self.username = username
self.password = password
self._request_auth()
finally:
self.transport.lock.release()
def auth_interactive(self, username, handler, event, submethods=''):
"""
response_list = handler(title, instructions, prompt_list)
"""
self.transport.lock.acquire()
try:
self.auth_event = event
self.auth_method = 'keyboard-interactive'
self.username = username
self.interactive_handler = handler
self.submethods = submethods
self._request_auth()
finally:
self.transport.lock.release()
def auth_gssapi_with_mic(self, username, gss_host, gss_deleg_creds, event):
self.transport.lock.acquire()
try:
self.auth_event = event
self.auth_method = 'gssapi-with-mic'
self.username = username
self.gss_host = gss_host
self.gss_deleg_creds = gss_deleg_creds
self._request_auth()
finally:
self.transport.lock.release()
def auth_gssapi_keyex(self, username, event):
self.transport.lock.acquire()
try:
self.auth_event = event
self.auth_method = 'gssapi-keyex'
self.username = username
self._request_auth()
finally:
self.transport.lock.release()
def abort(self):
if self.auth_event is not None:
self.auth_event.set()
### internals...
def _request_auth(self):
m = Message()
m.add_byte(cMSG_SERVICE_REQUEST)
m.add_string('ssh-userauth')
self.transport._send_message(m)
def _disconnect_service_not_available(self):
m = Message()
m.add_byte(cMSG_DISCONNECT)
m.add_int(DISCONNECT_SERVICE_NOT_AVAILABLE)
m.add_string('Service not available')
m.add_string('en')
self.transport._send_message(m)
self.transport.close()
def _disconnect_no_more_auth(self):
m = Message()
m.add_byte(cMSG_DISCONNECT)
m.add_int(DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE)
m.add_string('No more auth methods available')
m.add_string('en')
self.transport._send_message(m)
self.transport.close()
def _get_session_blob(self, key, service, username):
m = Message()
m.add_string(self.transport.session_id)
m.add_byte(cMSG_USERAUTH_REQUEST)
m.add_string(username)
m.add_string(service)
m.add_string('publickey')
m.add_boolean(True)
m.add_string(key.get_name())
m.add_string(key)
return m.asbytes()
def wait_for_response(self, event):
while True:
event.wait(0.1)
if not self.transport.is_active():
e = self.transport.get_exception()
if (e is None) or issubclass(e.__class__, EOFError):
e = AuthenticationException('Authentication failed.')
raise e
if event.is_set():
break
if not self.is_authenticated():
e = self.transport.get_exception()
if e is None:
e = AuthenticationException('Authentication failed.')
# this is horrible. Python Exception isn't yet descended from
# object, so type(e) won't work. :(
if issubclass(e.__class__, PartialAuthentication):
return e.allowed_types
raise e
return []
def _parse_service_request(self, m):
service = m.get_text()
if self.transport.server_mode and (service == 'ssh-userauth'):
# accepted
m = Message()
m.add_byte(cMSG_SERVICE_ACCEPT)
m.add_string(service)
self.transport._send_message(m)
return
# dunno this one
self._disconnect_service_not_available()
def _parse_service_accept(self, m):
service = m.get_text()
if service == 'ssh-userauth':
self.transport._log(DEBUG, 'userauth is OK')
m = Message()
m.add_byte(cMSG_USERAUTH_REQUEST)
m.add_string(self.username)
m.add_string('ssh-connection')
m.add_string(self.auth_method)
if self.auth_method == 'password':
m.add_boolean(False)
password = bytestring(self.password)
m.add_string(password)
elif self.auth_method == 'publickey':
m.add_boolean(True)
m.add_string(self.private_key.get_name())
m.add_string(self.private_key)
blob = self._get_session_blob(self.private_key, 'ssh-connection', self.username)
sig = self.private_key.sign_ssh_data(blob)
m.add_string(sig)
elif self.auth_method == 'keyboard-interactive':
m.add_string('')
m.add_string(self.submethods)
elif self.auth_method == "gssapi-with-mic":
sshgss = GSSAuth(self.auth_method, self.gss_deleg_creds)
m.add_bytes(sshgss.ssh_gss_oids())
# send the supported GSSAPI OIDs to the server
self.transport._send_message(m)
ptype, m = self.transport.packetizer.read_message()
if ptype == MSG_USERAUTH_BANNER:
self._parse_userauth_banner(m)
ptype, m = self.transport.packetizer.read_message()
if ptype == MSG_USERAUTH_GSSAPI_RESPONSE:
# Read the mechanism selected by the server. We send just
# the Kerberos V5 OID, so the server can only respond with
# this OID.
mech = m.get_string()
m = Message()
m.add_byte(cMSG_USERAUTH_GSSAPI_TOKEN)
m.add_string(sshgss.ssh_init_sec_context(self.gss_host,
mech,
self.username,))
self.transport._send_message(m)
while True:
ptype, m = self.transport.packetizer.read_message()
if ptype == MSG_USERAUTH_GSSAPI_TOKEN:
srv_token = m.get_string()
next_token = sshgss.ssh_init_sec_context(self.gss_host,
mech,
self.username,
srv_token)
# After this step the GSSAPI should not return any
# token. If it does, we keep sending the token to
# the server until no more token is returned.
if next_token is None:
break
else:
m = Message()
m.add_byte(cMSG_USERAUTH_GSSAPI_TOKEN)
m.add_string(next_token)
self.transport.send_message(m)
else:
raise SSHException("Received Package: %s" % MSG_NAMES[ptype])
m = Message()
m.add_byte(cMSG_USERAUTH_GSSAPI_MIC)
# send the MIC to the server
m.add_string(sshgss.ssh_get_mic(self.transport.session_id))
elif ptype == MSG_USERAUTH_GSSAPI_ERRTOK:
# RFC 4462 says we are not required to implement GSS-API
# error messages.
# See RFC 4462 Section 3.8 in
# http://www.ietf.org/rfc/rfc4462.txt
raise SSHException("Server returned an error token")
elif ptype == MSG_USERAUTH_GSSAPI_ERROR:
maj_status = m.get_int()
min_status = m.get_int()
err_msg = m.get_string()
lang_tag = m.get_string() # we don't care!
raise SSHException("GSS-API Error:\nMajor Status: %s\n\
Minor Status: %s\ \nError Message:\
%s\n") % (str(maj_status),
str(min_status),
err_msg)
elif ptype == MSG_USERAUTH_FAILURE:
self._parse_userauth_failure(m)
return
else:
raise SSHException("Received Package: %s" % MSG_NAMES[ptype])
elif self.auth_method == 'gssapi-keyex' and\
self.transport.gss_kex_used:
kexgss = self.transport.kexgss_ctxt
kexgss.set_username(self.username)
mic_token = kexgss.ssh_get_mic(self.transport.session_id)
m.add_string(mic_token)
elif self.auth_method == 'none':
pass
else:
raise SSHException('Unknown auth method "%s"' % self.auth_method)
self.transport._send_message(m)
else:
self.transport._log(DEBUG, 'Service request "%s" accepted (?)' % service)
def _send_auth_result(self, username, method, result):
# okay, send result
m = Message()
if result == AUTH_SUCCESSFUL:
self.transport._log(INFO, 'Auth granted (%s).' % method)
m.add_byte(cMSG_USERAUTH_SUCCESS)
self.authenticated = True
else:
self.transport._log(INFO, 'Auth rejected (%s).' % method)
m.add_byte(cMSG_USERAUTH_FAILURE)
m.add_string(self.transport.server_object.get_allowed_auths(username))
if result == AUTH_PARTIALLY_SUCCESSFUL:
m.add_boolean(True)
else:
m.add_boolean(False)
self.auth_fail_count += 1
self.transport._send_message(m)
if self.auth_fail_count >= 10:
self._disconnect_no_more_auth()
if result == AUTH_SUCCESSFUL:
self.transport._auth_trigger()
def _interactive_query(self, q):
# make interactive query instead of response
m = Message()
m.add_byte(cMSG_USERAUTH_INFO_REQUEST)
m.add_string(q.name)
m.add_string(q.instructions)
m.add_string(bytes())
m.add_int(len(q.prompts))
for p in q.prompts:
m.add_string(p[0])
m.add_boolean(p[1])
self.transport._send_message(m)
def _parse_userauth_request(self, m):
if not self.transport.server_mode:
# er, uh... what?
m = Message()
m.add_byte(cMSG_USERAUTH_FAILURE)
m.add_string('none')
m.add_boolean(False)
self.transport._send_message(m)
return
if self.authenticated:
# ignore
return
username = m.get_text()
service = m.get_text()
method = m.get_text()
self.transport._log(DEBUG, 'Auth request (type=%s) service=%s, username=%s' % (method, service, username))
if service != 'ssh-connection':
self._disconnect_service_not_available()
return
if (self.auth_username is not None) and (self.auth_username != username):
self.transport._log(WARNING, 'Auth rejected because the client attempted to change username in mid-flight')
self._disconnect_no_more_auth()
return
self.auth_username = username
# check if GSS-API authentication is enabled
gss_auth = self.transport.server_object.enable_auth_gssapi()
if method == 'none':
result = self.transport.server_object.check_auth_none(username)
elif method == 'password':
changereq = m.get_boolean()
password = m.get_binary()
try:
password = password.decode('UTF-8')
except UnicodeError:
# some clients/servers expect non-utf-8 passwords!
# in this case, just return the raw byte string.
pass
if changereq:
# always treated as failure, since we don't support changing passwords, but collect
# the list of valid auth types from the callback anyway
self.transport._log(DEBUG, 'Auth request to change passwords (rejected)')
newpassword = m.get_binary()
try:
newpassword = newpassword.decode('UTF-8', 'replace')
except UnicodeError:
pass
result = AUTH_FAILED
else:
result = self.transport.server_object.check_auth_password(username, password)
elif method == 'publickey':
sig_attached = m.get_boolean()
keytype = m.get_text()
keyblob = m.get_binary()
try:
key = self.transport._key_info[keytype](Message(keyblob))
except SSHException as e:
self.transport._log(INFO, 'Auth rejected: public key: %s' % str(e))
key = None
except:
self.transport._log(INFO, 'Auth rejected: unsupported or mangled public key')
key = None
if key is None:
self._disconnect_no_more_auth()
return
# first check if this key is okay... if not, we can skip the verify
result = self.transport.server_object.check_auth_publickey(username, key)
if result != AUTH_FAILED:
# key is okay, verify it
if not sig_attached:
# client wants to know if this key is acceptable, before it
# signs anything... send special "ok" message
m = Message()
m.add_byte(cMSG_USERAUTH_PK_OK)
m.add_string(keytype)
m.add_string(keyblob)
self.transport._send_message(m)
return
sig = Message(m.get_binary())
blob = self._get_session_blob(key, service, username)
if not key.verify_ssh_sig(blob, sig):
self.transport._log(INFO, 'Auth rejected: invalid signature')
result = AUTH_FAILED
elif method == 'keyboard-interactive':
lang = m.get_string()
submethods = m.get_string()
result = self.transport.server_object.check_auth_interactive(username, submethods)
if isinstance(result, InteractiveQuery):
# make interactive query instead of response
self._interactive_query(result)
return
elif method == "gssapi-with-mic" and gss_auth:
sshgss = GSSAuth(method)
# Read the number of OID mechanisms supported by the client.
# OpenSSH sends just one OID. It's the Kerveros V5 OID and that's
# the only OID we support.
mechs = m.get_int()
# We can't accept more than one OID, so if the SSH client sends
# more than one, disconnect.
if mechs > 1:
self.transport._log(INFO,
'Disconnect: Received more than one GSS-API OID mechanism')
self._disconnect_no_more_auth()
desired_mech = m.get_string()
mech_ok = sshgss.ssh_check_mech(desired_mech)
# if we don't support the mechanism, disconnect.
if not mech_ok:
self.transport._log(INFO,
'Disconnect: Received an invalid GSS-API OID mechanism')
self._disconnect_no_more_auth()
# send the Kerberos V5 GSSAPI OID to the client
supported_mech = sshgss.ssh_gss_oids("server")
# RFC 4462 says we are not required to implement GSS-API error
# messages. See section 3.8 in http://www.ietf.org/rfc/rfc4462.txt
while True:
m = Message()
m.add_byte(cMSG_USERAUTH_GSSAPI_RESPONSE)
m.add_bytes(supported_mech)
self.transport._send_message(m)
ptype, m = self.transport.packetizer.read_message()
if ptype == MSG_USERAUTH_GSSAPI_TOKEN:
client_token = m.get_string()
# use the client token as input to establish a secure
# context.
try:
token = sshgss.ssh_accept_sec_context(self.gss_host,
client_token,
username)
except Exception:
result = AUTH_FAILED
self._send_auth_result(username, method, result)
raise
if token is not None:
m = Message()
m.add_byte(cMSG_USERAUTH_GSSAPI_TOKEN)
m.add_string(token)
self.transport._send_message(m)
else:
raise SSHException("Client asked to handle paket %s"
%MSG_NAMES[ptype])
# check MIC
ptype, m = self.transport.packetizer.read_message()
if ptype == MSG_USERAUTH_GSSAPI_MIC:
break
mic_token = m.get_string()
try:
sshgss.ssh_check_mic(mic_token,
self.transport.session_id,
username)
except Exception:
result = AUTH_FAILED
self._send_auth_result(username, method, result)
raise
# TODO: Implement client credential saving.
# The OpenSSH server is able to create a TGT with the delegated
# client credentials, but this is not supported by GSS-API.
result = AUTH_SUCCESSFUL
self.transport.server_object.check_auth_gssapi_with_mic(username, result)
elif method == "gssapi-keyex" and gss_auth:
mic_token = m.get_string()
sshgss = self.transport.kexgss_ctxt
if sshgss is None:
# If there is no valid context, we reject the authentication
result = AUTH_FAILED
self._send_auth_result(username, method, result)
try:
sshgss.ssh_check_mic(mic_token,
self.transport.session_id,
self.auth_username)
except Exception:
result = AUTH_FAILED
self._send_auth_result(username, method, result)
raise
result = AUTH_SUCCESSFUL
self.transport.server_object.check_auth_gssapi_keyex(username, result)
else:
result = self.transport.server_object.check_auth_none(username)
# okay, send result
self._send_auth_result(username, method, result)
def _parse_userauth_success(self, m):
self.transport._log(INFO, 'Authentication (%s) successful!' % self.auth_method)
self.authenticated = True
self.transport._auth_trigger()
if self.auth_event is not None:
self.auth_event.set()
def _parse_userauth_failure(self, m):
authlist = m.get_list()
partial = m.get_boolean()
if partial:
self.transport._log(INFO, 'Authentication continues...')
self.transport._log(DEBUG, 'Methods: ' + str(authlist))
self.transport.saved_exception = PartialAuthentication(authlist)
elif self.auth_method not in authlist:
self.transport._log(DEBUG, 'Authentication type (%s) not permitted.' % self.auth_method)
self.transport._log(DEBUG, 'Allowed methods: ' + str(authlist))
self.transport.saved_exception = BadAuthenticationType('Bad authentication type', authlist)
else:
self.transport._log(INFO, 'Authentication (%s) failed.' % self.auth_method)
self.authenticated = False
self.username = None
if self.auth_event is not None:
self.auth_event.set()
def _parse_userauth_banner(self, m):
banner = m.get_string()
self.banner = banner
lang = m.get_string()
self.transport._log(INFO, 'Auth banner: %s' % banner)
# who cares.
def _parse_userauth_info_request(self, m):
if self.auth_method != 'keyboard-interactive':
raise SSHException('Illegal info request from server')
title = m.get_text()
instructions = m.get_text()
m.get_binary() # lang
prompts = m.get_int()
prompt_list = []
for i in range(prompts):
prompt_list.append((m.get_text(), m.get_boolean()))
response_list = self.interactive_handler(title, instructions, prompt_list)
m = Message()
m.add_byte(cMSG_USERAUTH_INFO_RESPONSE)
m.add_int(len(response_list))
for r in response_list:
m.add_string(r)
self.transport._send_message(m)
def _parse_userauth_info_response(self, m):
if not self.transport.server_mode:
raise SSHException('Illegal info response from server')
n = m.get_int()
responses = []
for i in range(n):
responses.append(m.get_text())
result = self.transport.server_object.check_auth_interactive_response(responses)
if isinstance(type(result), InteractiveQuery):
# make interactive query instead of response
self._interactive_query(result)
return
self._send_auth_result(self.auth_username, 'keyboard-interactive', result)
_handler_table = {
MSG_SERVICE_REQUEST: _parse_service_request,
MSG_SERVICE_ACCEPT: _parse_service_accept,
MSG_USERAUTH_REQUEST: _parse_userauth_request,
MSG_USERAUTH_SUCCESS: _parse_userauth_success,
MSG_USERAUTH_FAILURE: _parse_userauth_failure,
MSG_USERAUTH_BANNER: _parse_userauth_banner,
MSG_USERAUTH_INFO_REQUEST: _parse_userauth_info_request,
MSG_USERAUTH_INFO_RESPONSE: _parse_userauth_info_response,
}
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