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Diffstat (limited to 'paramiko/kex_gss.py')
| -rw-r--r-- | paramiko/kex_gss.py | 603 |
1 files changed, 603 insertions, 0 deletions
diff --git a/paramiko/kex_gss.py b/paramiko/kex_gss.py new file mode 100644 index 0000000..4e8380e --- /dev/null +++ b/paramiko/kex_gss.py @@ -0,0 +1,603 @@ +# Copyright (C) 2003-2007 Robey Pointer <robeypointer@gmail.com> +# Copyright (C) 2013-2014 science + computing ag +# Author: Sebastian Deiss <sebastian.deiss@t-online.de> +# +# +# 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. + + +""" +This module provides GSS-API / SSPI Key Exchange as defined in RFC 4462. + +.. note:: Credential delegation is not supported in server mode. + +.. note:: + `RFC 4462 Section 2.2 <http://www.ietf.org/rfc/rfc4462.txt>`_ says we are + not required to implement GSS-API error messages. Thus, in many methods + within this module, if an error occurs an exception will be thrown and the + connection will be terminated. + +.. seealso:: :doc:`/api/ssh_gss` + +.. versionadded:: 1.15 +""" + +from hashlib import sha1 + +from paramiko.common import * +from paramiko import util +from paramiko.message import Message +from paramiko.py3compat import byte_chr, long, byte_mask, byte_ord +from paramiko.ssh_exception import SSHException + + +MSG_KEXGSS_INIT, MSG_KEXGSS_CONTINUE, MSG_KEXGSS_COMPLETE, MSG_KEXGSS_HOSTKEY,\ +MSG_KEXGSS_ERROR = range(30, 35) +MSG_KEXGSS_GROUPREQ, MSG_KEXGSS_GROUP = range(40, 42) +c_MSG_KEXGSS_INIT, c_MSG_KEXGSS_CONTINUE, c_MSG_KEXGSS_COMPLETE,\ +c_MSG_KEXGSS_HOSTKEY, c_MSG_KEXGSS_ERROR = [byte_chr(c) for c in range(30, 35)] +c_MSG_KEXGSS_GROUPREQ, c_MSG_KEXGSS_GROUP = [byte_chr(c) for c in range(40, 42)] + + +class KexGSSGroup1(object): + """ + GSS-API / SSPI Authenticated Diffie-Hellman Key Exchange + as defined in `RFC 4462 Section 2 <http://www.ietf.org/rfc/rfc4462.txt>`_ + """ + # draft-ietf-secsh-transport-09.txt, page 17 + P = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF + G = 2 + b7fffffffffffffff = byte_chr(0x7f) + max_byte * 7 + b0000000000000000 = zero_byte * 8 + NAME = "gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==" + + def __init__(self, transport): + self.transport = transport + self.kexgss = self.transport.kexgss_ctxt + self.gss_host = None + self.x = 0 + self.e = 0 + self.f = 0 + + def start_kex(self): + """ + Start the GSS-API / SSPI Authenticated Diffie-Hellman Key Exchange. + """ + self.transport.gss_kex_used = True + self._generate_x() + if self.transport.server_mode: + # compute f = g^x mod p, but don't send it yet + self.f = pow(self.G, self.x, self.P) + self.transport._expect_packet(MSG_KEXGSS_INIT) + return + # compute e = g^x mod p (where g=2), and send it + self.e = pow(self.G, self.x, self.P) + # Initialize GSS-API Key Exchange + self.gss_host = self.transport.gss_host + m = Message() + m.add_byte(c_MSG_KEXGSS_INIT) + m.add_string(self.kexgss.ssh_init_sec_context(target=self.gss_host)) + m.add_mpint(self.e) + self.transport._send_message(m) + self.transport._expect_packet(MSG_KEXGSS_HOSTKEY, + MSG_KEXGSS_CONTINUE, + MSG_KEXGSS_COMPLETE, + MSG_KEXGSS_ERROR) + + def parse_next(self, ptype, m): + """ + Parse the next packet. + + :param char ptype: The type of the incomming packet + :param `.Message` m: The paket content + """ + if self.transport.server_mode and (ptype == MSG_KEXGSS_INIT): + return self._parse_kexgss_init(m) + elif not self.transport.server_mode and (ptype == MSG_KEXGSS_HOSTKEY): + return self._parse_kexgss_hostkey(m) + elif self.transport.server_mode and (ptype == MSG_KEXGSS_CONTINUE): + return self._parse_kexgss_continue(m) + elif not self.transport.server_mode and (ptype == MSG_KEXGSS_COMPLETE): + return self._parse_kexgss_complete(m) + elif ptype == MSG_KEXGSS_ERROR: + return self._parse_kexgss_error(m) + raise SSHException('GSS KexGroup1 asked to handle packet type %d' + % ptype) + + # ## internals... + + def _generate_x(self): + """ + generate an "x" (1 < x < q), where q is (p-1)/2. + p is a 128-byte (1024-bit) number, where the first 64 bits are 1. + therefore q can be approximated as a 2^1023. we drop the subset of + potential x where the first 63 bits are 1, because some of those will be + larger than q (but this is a tiny tiny subset of potential x). + """ + while 1: + x_bytes = self.transport.rng.read(128) + x_bytes = byte_mask(x_bytes[0], 0x7f) + x_bytes[1:] + if (x_bytes[:8] != self.b7fffffffffffffff) and \ + (x_bytes[:8] != self.b0000000000000000): + break + self.x = util.inflate_long(x_bytes) + + def _parse_kexgss_hostkey(self, m): + """ + Parse the SSH2_MSG_KEXGSS_HOSTKEY message (client mode). + + :param `.Message` m: The content of the SSH2_MSG_KEXGSS_HOSTKEY message + """ + # client mode + host_key = m.get_string() + self.transport.host_key = host_key + sig = m.get_string() + self.transport._verify_key(host_key, sig) + self.transport._expect_packet(MSG_KEXGSS_CONTINUE, + MSG_KEXGSS_COMPLETE) + + def _parse_kexgss_continue(self, m): + """ + Parse the SSH2_MSG_KEXGSS_CONTINUE message. + + :param `.Message` m: The content of the SSH2_MSG_KEXGSS_CONTINUE message + """ + if not self.transport.server_mode: + srv_token = m.get_string() + m = Message() + m.add_byte(c_MSG_KEXGSS_CONTINUE) + m.add_string(self.kexgss.ssh_init_sec_context(target=self.gss_host, + recv_token=srv_token)) + self.transport.send_message(m) + self.transport._expect_packet(MSG_KEXGSS_CONTINUE, + MSG_KEXGSS_COMPLETE, + MSG_KEXGSS_ERROR) + else: + pass + + def _parse_kexgss_complete(self, m): + """ + Parse the SSH2_MSG_KEXGSS_COMPLETE message (client mode). + + :param `.Message` m: The content of the SSH2_MSG_KEXGSS_COMPLETE message + """ + # client mode + if self.transport.host_key is None: + self.transport.host_key = NullHostKey() + self.f = m.get_mpint() + if (self.f < 1) or (self.f > self.P - 1): + raise SSHException('Server kex "f" is out of range') + mic_token = m.get_string() + # This must be TRUE, if there is a GSS-API token in this message. + bool = m.get_boolean() + srv_token = None + if bool: + srv_token = m.get_string() + K = pow(self.f, self.x, self.P) + # okay, build up the hash H of (V_C || V_S || I_C || I_S || K_S || e || f || K) + hm = Message() + hm.add(self.transport.local_version, self.transport.remote_version, + self.transport.local_kex_init, self.transport.remote_kex_init) + hm.add_string(self.transport.host_key.__str__()) + hm.add_mpint(self.e) + hm.add_mpint(self.f) + hm.add_mpint(K) + self.transport._set_K_H(K, sha1(str(hm)).digest()) + if srv_token is not None: + self.kexgss.ssh_init_sec_context(target=self.gss_host, + recv_token=srv_token) + self.kexgss.ssh_check_mic(mic_token, + self.transport.session_id) + else: + self.kexgss.ssh_check_mic(mic_token, + self.transport.session_id) + self.transport._activate_outbound() + + def _parse_kexgss_init(self, m): + """ + Parse the SSH2_MSG_KEXGSS_INIT message (server mode). + + :param `.Message` m: The content of the SSH2_MSG_KEXGSS_INIT message + """ + # server mode + client_token = m.get_string() + self.e = m.get_mpint() + if (self.e < 1) or (self.e > self.P - 1): + raise SSHException('Client kex "e" is out of range') + K = pow(self.e, self.x, self.P) + self.transport.host_key = NullHostKey() + key = self.transport.host_key.__str__() + # okay, build up the hash H of (V_C || V_S || I_C || I_S || K_S || e || f || K) + hm = Message() + hm.add(self.transport.remote_version, self.transport.local_version, + self.transport.remote_kex_init, self.transport.local_kex_init) + hm.add_string(key) + hm.add_mpint(self.e) + hm.add_mpint(self.f) + hm.add_mpint(K) + H = sha1(hm.asbytes()).digest() + self.transport._set_K_H(K, H) + srv_token = self.kexgss.ssh_accept_sec_context(self.gss_host, + client_token) + m = Message() + if self.kexgss._gss_srv_ctxt_status: + mic_token = self.kexgss.ssh_get_mic(self.transport.session_id, + gss_kex=True) + m.add_byte(c_MSG_KEXGSS_COMPLETE) + m.add_mpint(self.f) + m.add_string(mic_token) + if srv_token is not None: + m.add_boolean(True) + m.add_string(srv_token) + else: + m.add_boolean(False) + self.transport._send_message(m) + self.transport._activate_outbound() + else: + m.add_byte(c_MSG_KEXGSS_CONTINUE) + m.add_string(srv_token) + self.transport._send_message(m) + self.transport._expect_packet(MSG_KEXGSS_CONTINUE, + MSG_KEXGSS_COMPLETE, + MSG_KEXGSS_ERROR) + + def _parse_kexgss_error(self, m): + """ + Parse the SSH2_MSG_KEXGSS_ERROR message (client mode). + The server may send a GSS-API error message. if it does, we display + the error by throwing an exception (client mode). + + :param `.Message` m: The content of the SSH2_MSG_KEXGSS_ERROR message + :raise SSHException: Contains GSS-API major and minor status as well as + the error message and the language tag of the + message + """ + maj_status = m.get_int() + min_status = m.get_int() + err_msg = m.get_string() + lang_tag = m.get_string() # we don't care about the language! + raise SSHException("GSS-API Error:\nMajor Status: %s\nMinor Status: %s\ + \nError Message: %s\n") % (str(maj_status), + str(min_status), + err_msg) + + +class KexGSSGroup14(KexGSSGroup1): + """ + GSS-API / SSPI Authenticated Diffie-Hellman Group14 Key Exchange + as defined in `RFC 4462 Section 2 <http://www.ietf.org/rfc/rfc4462.txt>`_ + """ + P = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3DC2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F83655D23DCA3AD961C62F356208552BB9ED529077096966D670C354E4ABC9804F1746C08CA18217C32905E462E36CE3BE39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9DE2BCBF6955817183995497CEA956AE515D2261898FA051015728E5A8AACAA68FFFFFFFFFFFFFFFF + G = 2 + NAME = "gss-group14-sha1-toWM5Slw5Ew8Mqkay+al2g==" + + +class KexGSSGex(object): + """ + GSS-API / SSPI Authenticated Diffie-Hellman Group Exchange + as defined in `RFC 4462 Section 2 <http://www.ietf.org/rfc/rfc4462.txt>`_ + """ + NAME = "gss-gex-sha1-toWM5Slw5Ew8Mqkay+al2g==" + min_bits = 1024 + max_bits = 8192 + preferred_bits = 2048 + + def __init__(self, transport): + self.transport = transport + self.kexgss = self.transport.kexgss_ctxt + self.gss_host = None + self.p = None + self.q = None + self.g = None + self.x = None + self.e = None + self.f = None + self.old_style = False + + def start_kex(self): + """ + Start the GSS-API / SSPI Authenticated Diffie-Hellman Group Exchange + """ + self.transport.gss_kex_used = True + if self.transport.server_mode: + self.transport._expect_packet(MSG_KEXGSS_GROUPREQ) + return + # request a bit range: we accept (min_bits) to (max_bits), but prefer + # (preferred_bits). according to the spec, we shouldn't pull the + # minimum up above 1024. + self.gss_host = self.transport.gss_host + m = Message() + m.add_byte(c_MSG_KEXGSS_GROUPREQ) + m.add_int(self.min_bits) + m.add_int(self.preferred_bits) + m.add_int(self.max_bits) + self.transport._send_message(m) + self.transport._expect_packet(MSG_KEXGSS_GROUP) + + def parse_next(self, ptype, m): + """ + Parse the next packet. + + :param char ptype: The type of the incomming packet + :param `.Message` m: The paket content + """ + if ptype == MSG_KEXGSS_GROUPREQ: + return self._parse_kexgss_groupreq(m) + elif ptype == MSG_KEXGSS_GROUP: + return self._parse_kexgss_group(m) + elif ptype == MSG_KEXGSS_INIT: + return self._parse_kexgss_gex_init(m) + elif ptype == MSG_KEXGSS_HOSTKEY: + return self._parse_kexgss_hostkey(m) + elif ptype == MSG_KEXGSS_CONTINUE: + return self._parse_kexgss_continue(m) + elif ptype == MSG_KEXGSS_COMPLETE: + return self._parse_kexgss_complete(m) + elif ptype == MSG_KEXGSS_ERROR: + return self._parse_kexgss_error(m) + raise SSHException('KexGex asked to handle packet type %d' % ptype) + + # ## internals... + + def _generate_x(self): + # generate an "x" (1 < x < (p-1)/2). + q = (self.p - 1) // 2 + qnorm = util.deflate_long(q, 0) + qhbyte = byte_ord(qnorm[0]) + byte_count = len(qnorm) + qmask = 0xff + while not (qhbyte & 0x80): + qhbyte <<= 1 + qmask >>= 1 + while True: + x_bytes = self.transport.rng.read(byte_count) + x_bytes = byte_mask(x_bytes[0], qmask) + x_bytes[1:] + x = util.inflate_long(x_bytes, 1) + if (x > 1) and (x < q): + break + self.x = x + + def _parse_kexgss_groupreq(self, m): + """ + Parse the SSH2_MSG_KEXGSS_GROUPREQ message (server mode). + + :param `.Message` m: The content of the SSH2_MSG_KEXGSS_GROUPREQ message + """ + minbits = m.get_int() + preferredbits = m.get_int() + maxbits = m.get_int() + # smoosh the user's preferred size into our own limits + if preferredbits > self.max_bits: + preferredbits = self.max_bits + if preferredbits < self.min_bits: + preferredbits = self.min_bits + # fix min/max if they're inconsistent. technically, we could just pout + # and hang up, but there's no harm in giving them the benefit of the + # doubt and just picking a bitsize for them. + if minbits > preferredbits: + minbits = preferredbits + if maxbits < preferredbits: + maxbits = preferredbits + # now save a copy + self.min_bits = minbits + self.preferred_bits = preferredbits + self.max_bits = maxbits + # generate prime + pack = self.transport._get_modulus_pack() + if pack is None: + raise SSHException('Can\'t do server-side gex with no modulus pack') + self.transport._log(DEBUG, 'Picking p (%d <= %d <= %d bits)' % (minbits, preferredbits, maxbits)) + self.g, self.p = pack.get_modulus(minbits, preferredbits, maxbits) + m = Message() + m.add_byte(c_MSG_KEXGSS_GROUP) + m.add_mpint(self.p) + m.add_mpint(self.g) + self.transport._send_message(m) + self.transport._expect_packet(MSG_KEXGSS_INIT) + + def _parse_kexgss_group(self, m): + """ + Parse the SSH2_MSG_KEXGSS_GROUP message (client mode). + + :param `Message` m: The content of the SSH2_MSG_KEXGSS_GROUP message + """ + self.p = m.get_mpint() + self.g = m.get_mpint() + # reject if p's bit length < 1024 or > 8192 + bitlen = util.bit_length(self.p) + if (bitlen < 1024) or (bitlen > 8192): + raise SSHException('Server-generated gex p (don\'t ask) is out of range (%d bits)' % bitlen) + self.transport._log(DEBUG, 'Got server p (%d bits)' % bitlen) + self._generate_x() + # now compute e = g^x mod p + self.e = pow(self.g, self.x, self.p) + m = Message() + m.add_byte(c_MSG_KEXGSS_INIT) + m.add_string(self.kexgss.ssh_init_sec_context(target=self.gss_host)) + m.add_mpint(self.e) + self.transport._send_message(m) + self.transport._expect_packet(MSG_KEXGSS_HOSTKEY, + MSG_KEXGSS_CONTINUE, + MSG_KEXGSS_COMPLETE, + MSG_KEXGSS_ERROR) + + def _parse_kexgss_gex_init(self, m): + """ + Parse the SSH2_MSG_KEXGSS_INIT message (server mode). + + :param `Message` m: The content of the SSH2_MSG_KEXGSS_INIT message + """ + client_token = m.get_string() + self.e = m.get_mpint() + if (self.e < 1) or (self.e > self.p - 1): + raise SSHException('Client kex "e" is out of range') + self._generate_x() + self.f = pow(self.g, self.x, self.p) + K = pow(self.e, self.x, self.p) + self.transport.host_key = NullHostKey() + key = self.transport.host_key.__str__() + # okay, build up the hash H of (V_C || V_S || I_C || I_S || K_S || min || n || max || p || g || e || f || K) + hm = Message() + hm.add(self.transport.remote_version, self.transport.local_version, + self.transport.remote_kex_init, self.transport.local_kex_init, + key) + hm.add_int(self.min_bits) + hm.add_int(self.preferred_bits) + hm.add_int(self.max_bits) + hm.add_mpint(self.p) + hm.add_mpint(self.g) + hm.add_mpint(self.e) + hm.add_mpint(self.f) + hm.add_mpint(K) + H = sha1(hm.asbytes()).digest() + self.transport._set_K_H(K, H) + srv_token = self.kexgss.ssh_accept_sec_context(self.gss_host, + client_token) + m = Message() + if self.kexgss._gss_srv_ctxt_status: + mic_token = self.kexgss.ssh_get_mic(self.transport.session_id, + gss_kex=True) + m.add_byte(c_MSG_KEXGSS_COMPLETE) + m.add_mpint(self.f) + m.add_string(mic_token) + if srv_token is not None: + m.add_boolean(True) + m.add_string(srv_token) + else: + m.add_boolean(False) + self.transport._send_message(m) + self.transport._activate_outbound() + else: + m.add_byte(c_MSG_KEXGSS_CONTINUE) + m.add_string(srv_token) + self.transport._send_message(m) + self.transport._expect_packet(MSG_KEXGSS_CONTINUE, + MSG_KEXGSS_COMPLETE, + MSG_KEXGSS_ERROR) + + def _parse_kexgss_hostkey(self, m): + """ + Parse the SSH2_MSG_KEXGSS_HOSTKEY message (client mode). + + :param `Message` m: The content of the SSH2_MSG_KEXGSS_HOSTKEY message + """ + # client mode + host_key = m.get_string() + self.transport.host_key = host_key + sig = m.get_string() + self.transport._verify_key(host_key, sig) + self.transport._expect_packet(MSG_KEXGSS_CONTINUE, + MSG_KEXGSS_COMPLETE) + + def _parse_kexgss_continue(self, m): + """ + Parse the SSH2_MSG_KEXGSS_CONTINUE message. + + :param `Message` m: The content of the SSH2_MSG_KEXGSS_CONTINUE message + """ + if not self.transport.server_mode: + srv_token = m.get_string() + m = Message() + m.add_byte(c_MSG_KEXGSS_CONTINUE) + m.add_string(self.kexgss.ssh_init_sec_context(target=self.gss_host, + recv_token=srv_token)) + self.transport.send_message(m) + self.transport._expect_packet(MSG_KEXGSS_CONTINUE, + MSG_KEXGSS_COMPLETE, + MSG_KEXGSS_ERROR) + else: + pass + + def _parse_kexgss_complete(self, m): + """ + Parse the SSH2_MSG_KEXGSS_COMPLETE message (client mode). + + :param `Message` m: The content of the SSH2_MSG_KEXGSS_COMPLETE message + """ + if self.transport.host_key is None: + self.transport.host_key = NullHostKey() + self.f = m.get_mpint() + mic_token = m.get_string() + # This must be TRUE, if there is a GSS-API token in this message. + bool = m.get_boolean() + srv_token = None + if bool: + srv_token = m.get_string() + if (self.f < 1) or (self.f > self.p - 1): + raise SSHException('Server kex "f" is out of range') + K = pow(self.f, self.x, self.p) + # okay, build up the hash H of (V_C || V_S || I_C || I_S || K_S || min || n || max || p || g || e || f || K) + hm = Message() + hm.add(self.transport.local_version, self.transport.remote_version, + self.transport.local_kex_init, self.transport.remote_kex_init, + self.transport.host_key.__str__()) + if not self.old_style: + hm.add_int(self.min_bits) + hm.add_int(self.preferred_bits) + if not self.old_style: + hm.add_int(self.max_bits) + hm.add_mpint(self.p) + hm.add_mpint(self.g) + hm.add_mpint(self.e) + hm.add_mpint(self.f) + hm.add_mpint(K) + H = sha1(hm.asbytes()).digest() + self.transport._set_K_H(K, H) + if srv_token is not None: + self.kexgss.ssh_init_sec_context(target=self.gss_host, + recv_token=srv_token) + self.kexgss.ssh_check_mic(mic_token, + self.transport.session_id) + else: + self.kexgss.ssh_check_mic(mic_token, + self.transport.session_id) + self.transport._activate_outbound() + + def _parse_kexgss_error(self, m): + """ + Parse the SSH2_MSG_KEXGSS_ERROR message (client mode). + The server may send a GSS-API error message. if it does, we display + the error by throwing an exception (client mode). + + :param `Message` m: The content of the SSH2_MSG_KEXGSS_ERROR message + :raise SSHException: Contains GSS-API major and minor status as well as + the error message and the language tag of the + message + """ + maj_status = m.get_int() + min_status = m.get_int() + err_msg = m.get_string() + lang_tag = m.get_string() # we don't care about the language! + raise SSHException("GSS-API Error:\nMajor Status: %s\nMinor Status: %s\ + \nError Message: %s\n") % (str(maj_status), + str(min_status), + err_msg) + + +class NullHostKey(object): + """ + This class represents the Null Host Key for GSS-API Key Exchange + as defined in `RFC 4462 Section 5 <http://www.ietf.org/rfc/rfc4462.txt>`_ + """ + def __init__(self): + self.key = "" + + def __str__(self): + return self.key + + def get_name(self): + return self.key |