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|
## tls_nb.py
## based on transports_nb.py
##
## Copyright (C) 2003-2004 Alexey "Snake" Nezhdanov
## modified by Dimitur Kirov <dkirov@gmail.com>
## modified by Tomas Karasek <tom.to.the.k@gmail.com>
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2, or (at your option)
## any later version.
##
## This program 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 General Public License for more details.
from __future__ import print_function
import socket
import ssl
from .plugin import PlugIn
import sys
import os
import time
import traceback
import logging
log = logging.getLogger('nbxmpp.tls_nb')
USE_PYOPENSSL = False
PYOPENSSL = 'PYOPENSSL'
PYSTDLIB = 'PYSTDLIB'
try:
#raise ImportError("Manually disabled PyOpenSSL")
import OpenSSL.SSL
import OpenSSL.crypto
USE_PYOPENSSL = True
log.info("PyOpenSSL loaded")
except ImportError:
log.debug("Import of PyOpenSSL failed:", exc_info=True)
# FIXME: Remove these prints before release, replace with a warning dialog.
print("=" * 79, file=sys.stderr)
print("PyOpenSSL not found, falling back to Python builtin SSL objects (insecure).", file=sys.stderr)
print("=" * 79, file=sys.stderr)
def gattr(obj, attr, default=None):
try:
return getattr(obj, attr)
except AttributeError:
return default
class SSLWrapper:
"""
Abstract SSLWrapper base class
"""
class Error(IOError):
"""
Generic SSL Error Wrapper
"""
def __init__(self, sock=None, exc=None, errno=None, strerror=None,
peer=None):
self.parent = IOError
errno = errno or gattr(exc, 'errno') or exc.args[0]
strerror = strerror or gattr(exc, 'strerror') or gattr(exc, 'args')
if not isinstance(strerror, str):
strerror = repr(strerror)
self.sock = sock
self.exc = exc
self.peer = peer
self.exc_name = None
self.exc_args = None
self.exc_str = None
self.exc_repr = None
if self.exc is not None:
self.exc_name = str(self.exc.__class__)
self.exc_args = gattr(self.exc, 'args')
self.exc_str = str(self.exc)
self.exc_repr = repr(self.exc)
if not errno:
try:
if isinstance(exc, OpenSSL.SSL.SysCallError):
if self.exc_args[0] > 0:
errno = self.exc_args[0]
strerror = self.exc_args[1]
except: pass
self.parent.__init__(self, errno, strerror)
if self.peer is None and sock is not None:
try:
ppeer = self.sock.getpeername()
if len(ppeer) == 2 and isinstance(ppeer[0], str) \
and isinstance(ppeer[1], int):
self.peer = ppeer
except:
pass
def __str__(self):
s = str(self.__class__)
if self.peer:
s += " for %s:%d" % self.peer
if self.errno is not None:
s += ": [Errno: %d]" % self.errno
if self.strerror:
s += " (%s)" % self.strerror
if self.exc_name:
s += ", Caused by %s" % self.exc_name
if self.exc_str:
if self.strerror:
s += "(%s)" % self.exc_str
else: s += "(%s)" % str(self.exc_args)
return s
def __init__(self, sslobj, sock=None):
self.sslobj = sslobj
self.sock = sock
log.debug("%s.__init__ called with %s", self.__class__, sslobj)
def recv(self, data, flags=None):
"""
Receive wrapper for SSL object
We can return None out of this function to signal that no data is
available right now. Better than an exception, which differs
depending on which SSL lib we're using. Unfortunately returning ''
can indicate that the socket has been closed, so to be sure, we avoid
this by returning None.
"""
raise NotImplementedError
def send(self, data, flags=None, now=False):
"""
Send wrapper for SSL object
"""
raise NotImplementedError
class PyOpenSSLWrapper(SSLWrapper):
"""
Wrapper class for PyOpenSSL's recv() and send() methods
"""
def __init__(self, *args):
self.parent = SSLWrapper
self.parent.__init__(self, *args)
def is_numtoolarge(self, e):
''' Magic methods don't need documentation '''
t = ('asn1 encoding routines', 'a2d_ASN1_OBJECT', 'first num too large')
return (isinstance(e.args, (list, tuple)) and len(e.args) == 1 and
isinstance(e.args[0], (list, tuple)) and len(e.args[0]) == 2 and
e.args[0][0] == e.args[0][1] == t)
def recv(self, bufsize, flags=None):
retval = None
try:
if flags is None:
retval = self.sslobj.recv(bufsize)
else:
retval = self.sslobj.recv(bufsize, flags)
except (OpenSSL.SSL.WantReadError, OpenSSL.SSL.WantWriteError) as e:
log.debug("Recv: Want-error: " + repr(e))
except OpenSSL.SSL.SysCallError as e:
log.debug("Recv: Got OpenSSL.SSL.SysCallError: " + repr(e),
exc_info=True)
raise SSLWrapper.Error(self.sock or self.sslobj, e)
except OpenSSL.SSL.ZeroReturnError as e:
# end-of-connection raises ZeroReturnError instead of having the
# connection's .recv() method return a zero-sized result.
raise SSLWrapper.Error(self.sock or self.sslobj, e, -1)
except OpenSSL.SSL.Error as e:
if self.is_numtoolarge(e):
# warn, but ignore this exception
log.warning("Recv: OpenSSL: asn1enc: first num too large (ignored)")
else:
log.debug("Recv: Caught OpenSSL.SSL.Error:", exc_info=True)
raise SSLWrapper.Error(self.sock or self.sslobj, e)
return retval
def send(self, data, flags=None, now=False):
try:
if flags is None:
return self.sslobj.send(data)
else:
return self.sslobj.send(data, flags)
except (OpenSSL.SSL.WantReadError, OpenSSL.SSL.WantWriteError) as e:
#log.debug("Send: " + repr(e))
time.sleep(0.1) # prevent 100% CPU usage
except OpenSSL.SSL.SysCallError as e:
log.error("Send: Got OpenSSL.SSL.SysCallError: " + repr(e),
exc_info=True)
raise SSLWrapper.Error(self.sock or self.sslobj, e)
except OpenSSL.SSL.Error as e:
if self.is_numtoolarge(e):
# warn, but ignore this exception
log.warning("Send: OpenSSL: asn1enc: first num too large (ignored)")
else:
log.error("Send: Caught OpenSSL.SSL.Error:", exc_info=True)
raise SSLWrapper.Error(self.sock or self.sslobj, e)
return 0
class StdlibSSLWrapper(SSLWrapper):
"""
Wrapper class for Python socket.ssl read() and write() methods
"""
def __init__(self, *args):
self.parent = SSLWrapper
self.parent.__init__(self, *args)
def recv(self, bufsize, flags=None):
# we simply ignore flags since ssl object doesn't support it
try:
return self.sslobj.read(bufsize)
except ssl.SSLError as e:
log.debug("Recv: Caught ssl.SSLError: " + repr(e), exc_info=True)
if e.args[0] not in (ssl.SSL_ERROR_WANT_READ,
ssl.SSL_ERROR_WANT_WRITE):
raise SSLWrapper.Error(self.sock or self.sslobj, e)
return None
def send(self, data, flags=None, now=False):
# we simply ignore flags since ssl object doesn't support it
try:
return self.sslobj.write(data)
except ssl.SSLError as e:
log.debug("Send: Caught socket.sslerror:", exc_info=True)
if e.args[0] not in (ssl.SSL_ERROR_WANT_READ,
ssl.SSL_ERROR_WANT_WRITE):
raise SSLWrapper.Error(self.sock or self.sslobj, e)
return 0
class NonBlockingTLS(PlugIn):
"""
TLS connection used to encrypts already estabilished tcp connection
Can be plugged into NonBlockingTCP and will make use of StdlibSSLWrapper or
PyOpenSSLWrapper.
"""
def __init__(self, cacerts, mycerts, tls_version, cipher_list):
"""
:param cacerts: path to pem file with certificates of known XMPP servers
:param mycerts: path to pem file with certificates of user trusted
servers
:param tls_version: The lowest supported TLS version. If None is
provided, version 1.0 is used. For example setting to 1.1 will
enable TLS 1.1, TLS 1.2 and all further protocols
:param cipher_list: list of ciphers to use when connection to server. If
None is provided, a default list is used: HIGH:!aNULL:RC4-SHA
"""
PlugIn.__init__(self)
self.cacerts = cacerts
self.mycerts = mycerts
if cipher_list is None:
self.cipher_list = 'HIGH:!aNULL:RC4-SHA'
else:
self.cipher_list = cipher_list
if tls_version is None:
self.tls_version = '1.0'
else:
self.tls_version = tls_version
def plugin(self, owner):
"""
Use to PlugIn TLS into transport and start establishing immediately.
Returns True if TLS/SSL was established correctly, otherwise False
"""
log.info('Starting TLS estabilishing')
try:
res = self._startSSL()
except Exception as e:
log.error("PlugIn: while trying _startSSL():", exc_info=True)
return False
return res
def _dumpX509(self, cert, stream=sys.stderr):
try:
print("Digest (SHA-2 256):" + cert.digest("sha256"), file=stream)
except ValueError: # Old OpenSSL version
pass
print("Digest (SHA-1):" + cert.digest("sha1"), file=stream)
print("Digest (MD5):" + cert.digest("md5"), file=stream)
print("Serial #:" + cert.get_serial_number(), file=stream)
print("Version:" + cert.get_version(), file=stream)
print("Expired:" + ("Yes" if cert.has_expired() else "No"), file=stream)
print("Subject:", file=stream)
self._dumpX509Name(cert.get_subject(), stream)
print("Issuer:", file=stream)
self._dumpX509Name(cert.get_issuer(), stream)
self._dumpPKey(cert.get_pubkey(), stream)
def _dumpX509Name(self, name, stream=sys.stderr):
print("X509Name:" + str(name), file=stream)
def _dumpPKey(self, pkey, stream=sys.stderr):
typedict = {OpenSSL.crypto.TYPE_RSA: "RSA",
OpenSSL.crypto.TYPE_DSA: "DSA"}
print("PKey bits:" + pkey.bits(), file=stream)
print("PKey type: %s (%d)" % (typedict.get(pkey.type(),
"Unknown"), pkey.type()), file=stream)
def _startSSL(self):
"""
Immediatedly switch socket to TLS mode. Used internally
"""
log.debug("_startSSL called")
if USE_PYOPENSSL:
result = self._startSSL_pyOpenSSL()
else:
result = self._startSSL_stdlib()
if result:
log.debug('Synchronous handshake completed')
return True
else:
return False
def _load_cert_file(self, cert_path, cert_store, logg=True):
if not os.path.isfile(cert_path):
return
try:
f = open(cert_path)
except IOError as e:
log.warning('Unable to open certificate file %s: %s' % \
(cert_path, str(e)))
return
lines = f.readlines()
i = 0
begin = -1
for line in lines:
if 'BEGIN CERTIFICATE' in line:
begin = i
elif 'END CERTIFICATE' in line and begin > -1:
cert = ''.join(lines[begin:i+2])
try:
x509cert = OpenSSL.crypto.load_certificate(
OpenSSL.crypto.FILETYPE_PEM, cert)
cert_store.add_cert(x509cert)
except OpenSSL.crypto.Error as exception_obj:
if logg:
log.warning('Unable to load a certificate from file %s: %s' %\
(cert_path, exception_obj.args[0][0][2]))
except:
log.warning('Unknown error while loading certificate from file '
'%s' % cert_path)
begin = -1
i += 1
f.close()
def _startSSL_pyOpenSSL(self):
log.debug("_startSSL_pyOpenSSL called")
tcpsock = self._owner
# See http://docs.python.org/dev/library/ssl.html
tcpsock._sslContext = OpenSSL.SSL.Context(OpenSSL.SSL.SSLv23_METHOD)
flags = OpenSSL.SSL.OP_NO_SSLv2 | OpenSSL.SSL.OP_NO_SSLv3 | \
OpenSSL.SSL.OP_SINGLE_DH_USE
try:
flags |= OpenSSL.SSL.OP_NO_TICKET
except AttributeError as e:
# py-OpenSSL < 0.9 or old OpenSSL
flags |= 16384
try:
# OpenSSL 1.0.1d supports TLS 1.1 and TLS 1.2 and
# fixes renegotiation in TLS 1.1, 1.2 by using the correct TLS version.
if OpenSSL.SSL.OPENSSL_VERSION_NUMBER >= 0x1000104f:
if self.tls_version != '1.0':
flags |= OpenSSL.SSL.OP_NO_TLSv1
if self.tls_version not in ('1.0', '1.1'):
try:
flags |= OpenSSL.SSL.OP_NO_TLSv1_1
except AttributeError as e:
# older py-OpenSSL
flags |= 0x10000000
except AttributeError as e:
pass # much older py-OpenSSL
tcpsock._sslContext.set_options(flags)
try: # Supported only pyOpenSSL >= 0.14
# Disable session resumption, protection against Triple Handshakes TLS attack
tcpsock._sslContext.set_session_cache_mode(OpenSSL.SSL.SESS_CACHE_OFF)
except AttributeError as e:
pass
# NonBlockingHTTPBOSH instance has no attribute _owner
if hasattr(tcpsock, '_owner') and tcpsock._owner._caller.client_cert \
and os.path.exists(tcpsock._owner._caller.client_cert):
conn = tcpsock._owner._caller
log.debug('Using client cert and key from %s' % conn.client_cert)
try:
p12 = OpenSSL.crypto.load_pkcs12(open(conn.client_cert).read(),
conn.client_cert_passphrase)
except OpenSSL.crypto.Error as exception_obj:
log.warning('Unable to load client pkcs12 certificate from '
'file %s: %s ... Is it a valid PKCS12 cert?' % \
(conn.client_cert, exception_obj.args))
except:
log.warning('Unknown error while loading certificate from file '
'%s' % conn.client_cert)
else:
log.info('PKCS12 Client cert loaded OK')
try:
tcpsock._sslContext.use_certificate(p12.get_certificate())
tcpsock._sslContext.use_privatekey(p12.get_privatekey())
log.info('p12 cert and key loaded')
except OpenSSL.crypto.Error as exception_obj:
log.warning('Unable to extract client certificate from '
'file %s' % conn.client_cert)
except Exception as msg:
log.warning('Unknown error extracting client certificate '
'from file %s: %s' % (conn.client_cert, msg))
else:
log.info('client cert and key loaded OK')
tcpsock.ssl_errnum = 0
tcpsock._sslContext.set_verify(OpenSSL.SSL.VERIFY_PEER,
self._ssl_verify_callback)
tcpsock._sslContext.set_cipher_list(self.cipher_list)
store = tcpsock._sslContext.get_cert_store()
self._load_cert_file(self.cacerts, store)
self._load_cert_file(self.mycerts, store)
if os.path.isdir('/etc/ssl/certs'):
for f in os.listdir('/etc/ssl/certs'):
# We don't logg because there is a lot a duplicated certs in this
# folder
self._load_cert_file(os.path.join('/etc/ssl/certs', f), store,
logg=False)
tcpsock._sslObj = OpenSSL.SSL.Connection(tcpsock._sslContext,
tcpsock._sock)
tcpsock._sslObj.set_connect_state() # set to client mode
wrapper = PyOpenSSLWrapper(tcpsock._sslObj)
tcpsock._recv = wrapper.recv
tcpsock._send = wrapper.send
log.debug("Initiating handshake...")
try:
tcpsock._sslObj.do_handshake()
except (OpenSSL.SSL.WantReadError, OpenSSL.SSL.WantWriteError) as e:
pass
except:
log.error('Error while TLS handshake: ', exc_info=True)
return False
self._owner.ssl_lib = PYOPENSSL
return True
def _startSSL_stdlib(self):
log.debug("_startSSL_stdlib called")
tcpsock=self._owner
try:
tcpsock._sslObj = ssl.wrap_socket(tcpsock._sock,
ssl_version=ssl.PROTOCOL_TLSv1, do_handshake_on_connect=False)
wrapper = StdlibSSLWrapper(tcpsock._sslObj, tcpsock._sock)
tcpsock._recv = wrapper.recv
tcpsock._send = wrapper.send
log.debug("Initiating handshake...")
try:
tcpsock._sslObj.do_handshake()
except (ssl.SSLError) as e:
if e.args[0] in (ssl.SSL_ERROR_WANT_READ,
ssl.SSL_ERROR_WANT_WRITE):
pass
else:
log.error('Error while TLS handshake: ', exc_info=True)
return False
except:
log.error('Error while TLS handshake: ', exc_info=True)
return False
except:
log.error("Exception caught in _startSSL_stdlib:", exc_info=True)
return False
self._owner.ssl_lib = PYSTDLIB
return True
def _ssl_verify_callback(self, sslconn, cert, errnum, depth, ok):
# Exceptions can't propagate up through this callback, so print them here.
try:
if depth == 0:
self._owner.ssl_certificate = cert
if not ok:
self._owner.ssl_errnum = errnum
return True
except:
log.error("Exception caught in _ssl_info_callback:", exc_info=True)
# Make sure something is printed, even if log is disabled.
traceback.print_exc()
def get_channel_binding(self):
"""
Get channel binding data. RFC 5929
"""
sslObj = self._owner._sslObj
try:
if USE_PYOPENSSL:
return sslObj.get_finished()
else:
return sslObj.get_channel_binding()
except AttributeError:
raise NotImplementedError
|
