341 lines
12 KiB
Python
341 lines
12 KiB
Python
from __future__ import absolute_import
|
|
import errno
|
|
import warnings
|
|
import hmac
|
|
|
|
from binascii import hexlify, unhexlify
|
|
from hashlib import md5, sha1, sha256
|
|
|
|
from ..exceptions import SSLError, InsecurePlatformWarning, SNIMissingWarning
|
|
|
|
|
|
SSLContext = None
|
|
HAS_SNI = False
|
|
IS_PYOPENSSL = False
|
|
IS_SECURETRANSPORT = False
|
|
|
|
# Maps the length of a digest to a possible hash function producing this digest
|
|
HASHFUNC_MAP = {
|
|
32: md5,
|
|
40: sha1,
|
|
64: sha256,
|
|
}
|
|
|
|
|
|
def _const_compare_digest_backport(a, b):
|
|
"""
|
|
Compare two digests of equal length in constant time.
|
|
|
|
The digests must be of type str/bytes.
|
|
Returns True if the digests match, and False otherwise.
|
|
"""
|
|
result = abs(len(a) - len(b))
|
|
for l, r in zip(bytearray(a), bytearray(b)):
|
|
result |= l ^ r
|
|
return result == 0
|
|
|
|
|
|
_const_compare_digest = getattr(hmac, 'compare_digest',
|
|
_const_compare_digest_backport)
|
|
|
|
|
|
try: # Test for SSL features
|
|
import ssl
|
|
from ssl import wrap_socket, CERT_NONE, PROTOCOL_SSLv23
|
|
from ssl import HAS_SNI # Has SNI?
|
|
except ImportError:
|
|
pass
|
|
|
|
|
|
try:
|
|
from ssl import OP_NO_SSLv2, OP_NO_SSLv3, OP_NO_COMPRESSION
|
|
except ImportError:
|
|
OP_NO_SSLv2, OP_NO_SSLv3 = 0x1000000, 0x2000000
|
|
OP_NO_COMPRESSION = 0x20000
|
|
|
|
# A secure default.
|
|
# Sources for more information on TLS ciphers:
|
|
#
|
|
# - https://wiki.mozilla.org/Security/Server_Side_TLS
|
|
# - https://www.ssllabs.com/projects/best-practices/index.html
|
|
# - https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
|
|
#
|
|
# The general intent is:
|
|
# - Prefer TLS 1.3 cipher suites
|
|
# - prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE),
|
|
# - prefer ECDHE over DHE for better performance,
|
|
# - prefer any AES-GCM and ChaCha20 over any AES-CBC for better performance and
|
|
# security,
|
|
# - prefer AES-GCM over ChaCha20 because hardware-accelerated AES is common,
|
|
# - disable NULL authentication, MD5 MACs and DSS for security reasons.
|
|
DEFAULT_CIPHERS = ':'.join([
|
|
'TLS13-AES-256-GCM-SHA384',
|
|
'TLS13-CHACHA20-POLY1305-SHA256',
|
|
'TLS13-AES-128-GCM-SHA256',
|
|
'ECDH+AESGCM',
|
|
'ECDH+CHACHA20',
|
|
'DH+AESGCM',
|
|
'DH+CHACHA20',
|
|
'ECDH+AES256',
|
|
'DH+AES256',
|
|
'ECDH+AES128',
|
|
'DH+AES',
|
|
'RSA+AESGCM',
|
|
'RSA+AES',
|
|
'!aNULL',
|
|
'!eNULL',
|
|
'!MD5',
|
|
])
|
|
|
|
try:
|
|
from ssl import SSLContext # Modern SSL?
|
|
except ImportError:
|
|
import sys
|
|
|
|
class SSLContext(object): # Platform-specific: Python 2 & 3.1
|
|
supports_set_ciphers = ((2, 7) <= sys.version_info < (3,) or
|
|
(3, 2) <= sys.version_info)
|
|
|
|
def __init__(self, protocol_version):
|
|
self.protocol = protocol_version
|
|
# Use default values from a real SSLContext
|
|
self.check_hostname = False
|
|
self.verify_mode = ssl.CERT_NONE
|
|
self.ca_certs = None
|
|
self.options = 0
|
|
self.certfile = None
|
|
self.keyfile = None
|
|
self.ciphers = None
|
|
|
|
def load_cert_chain(self, certfile, keyfile):
|
|
self.certfile = certfile
|
|
self.keyfile = keyfile
|
|
|
|
def load_verify_locations(self, cafile=None, capath=None):
|
|
self.ca_certs = cafile
|
|
|
|
if capath is not None:
|
|
raise SSLError("CA directories not supported in older Pythons")
|
|
|
|
def set_ciphers(self, cipher_suite):
|
|
if not self.supports_set_ciphers:
|
|
raise TypeError(
|
|
'Your version of Python does not support setting '
|
|
'a custom cipher suite. Please upgrade to Python '
|
|
'2.7, 3.2, or later if you need this functionality.'
|
|
)
|
|
self.ciphers = cipher_suite
|
|
|
|
def wrap_socket(self, socket, server_hostname=None, server_side=False):
|
|
warnings.warn(
|
|
'A true SSLContext object is not available. This prevents '
|
|
'urllib3 from configuring SSL appropriately and may cause '
|
|
'certain SSL connections to fail. You can upgrade to a newer '
|
|
'version of Python to solve this. For more information, see '
|
|
'https://urllib3.readthedocs.io/en/latest/advanced-usage.html'
|
|
'#ssl-warnings',
|
|
InsecurePlatformWarning
|
|
)
|
|
kwargs = {
|
|
'keyfile': self.keyfile,
|
|
'certfile': self.certfile,
|
|
'ca_certs': self.ca_certs,
|
|
'cert_reqs': self.verify_mode,
|
|
'ssl_version': self.protocol,
|
|
'server_side': server_side,
|
|
}
|
|
if self.supports_set_ciphers: # Platform-specific: Python 2.7+
|
|
return wrap_socket(socket, ciphers=self.ciphers, **kwargs)
|
|
else: # Platform-specific: Python 2.6
|
|
return wrap_socket(socket, **kwargs)
|
|
|
|
|
|
def assert_fingerprint(cert, fingerprint):
|
|
"""
|
|
Checks if given fingerprint matches the supplied certificate.
|
|
|
|
:param cert:
|
|
Certificate as bytes object.
|
|
:param fingerprint:
|
|
Fingerprint as string of hexdigits, can be interspersed by colons.
|
|
"""
|
|
|
|
fingerprint = fingerprint.replace(':', '').lower()
|
|
digest_length = len(fingerprint)
|
|
hashfunc = HASHFUNC_MAP.get(digest_length)
|
|
if not hashfunc:
|
|
raise SSLError(
|
|
'Fingerprint of invalid length: {0}'.format(fingerprint))
|
|
|
|
# We need encode() here for py32; works on py2 and p33.
|
|
fingerprint_bytes = unhexlify(fingerprint.encode())
|
|
|
|
cert_digest = hashfunc(cert).digest()
|
|
|
|
if not _const_compare_digest(cert_digest, fingerprint_bytes):
|
|
raise SSLError('Fingerprints did not match. Expected "{0}", got "{1}".'
|
|
.format(fingerprint, hexlify(cert_digest)))
|
|
|
|
|
|
def resolve_cert_reqs(candidate):
|
|
"""
|
|
Resolves the argument to a numeric constant, which can be passed to
|
|
the wrap_socket function/method from the ssl module.
|
|
Defaults to :data:`ssl.CERT_NONE`.
|
|
If given a string it is assumed to be the name of the constant in the
|
|
:mod:`ssl` module or its abbrevation.
|
|
(So you can specify `REQUIRED` instead of `CERT_REQUIRED`.
|
|
If it's neither `None` nor a string we assume it is already the numeric
|
|
constant which can directly be passed to wrap_socket.
|
|
"""
|
|
if candidate is None:
|
|
return CERT_NONE
|
|
|
|
if isinstance(candidate, str):
|
|
res = getattr(ssl, candidate, None)
|
|
if res is None:
|
|
res = getattr(ssl, 'CERT_' + candidate)
|
|
return res
|
|
|
|
return candidate
|
|
|
|
|
|
def resolve_ssl_version(candidate):
|
|
"""
|
|
like resolve_cert_reqs
|
|
"""
|
|
if candidate is None:
|
|
return PROTOCOL_SSLv23
|
|
|
|
if isinstance(candidate, str):
|
|
res = getattr(ssl, candidate, None)
|
|
if res is None:
|
|
res = getattr(ssl, 'PROTOCOL_' + candidate)
|
|
return res
|
|
|
|
return candidate
|
|
|
|
|
|
def create_urllib3_context(ssl_version=None, cert_reqs=None,
|
|
options=None, ciphers=None):
|
|
"""All arguments have the same meaning as ``ssl_wrap_socket``.
|
|
|
|
By default, this function does a lot of the same work that
|
|
``ssl.create_default_context`` does on Python 3.4+. It:
|
|
|
|
- Disables SSLv2, SSLv3, and compression
|
|
- Sets a restricted set of server ciphers
|
|
|
|
If you wish to enable SSLv3, you can do::
|
|
|
|
from urllib3.util import ssl_
|
|
context = ssl_.create_urllib3_context()
|
|
context.options &= ~ssl_.OP_NO_SSLv3
|
|
|
|
You can do the same to enable compression (substituting ``COMPRESSION``
|
|
for ``SSLv3`` in the last line above).
|
|
|
|
:param ssl_version:
|
|
The desired protocol version to use. This will default to
|
|
PROTOCOL_SSLv23 which will negotiate the highest protocol that both
|
|
the server and your installation of OpenSSL support.
|
|
:param cert_reqs:
|
|
Whether to require the certificate verification. This defaults to
|
|
``ssl.CERT_REQUIRED``.
|
|
:param options:
|
|
Specific OpenSSL options. These default to ``ssl.OP_NO_SSLv2``,
|
|
``ssl.OP_NO_SSLv3``, ``ssl.OP_NO_COMPRESSION``.
|
|
:param ciphers:
|
|
Which cipher suites to allow the server to select.
|
|
:returns:
|
|
Constructed SSLContext object with specified options
|
|
:rtype: SSLContext
|
|
"""
|
|
context = SSLContext(ssl_version or ssl.PROTOCOL_SSLv23)
|
|
|
|
# Setting the default here, as we may have no ssl module on import
|
|
cert_reqs = ssl.CERT_REQUIRED if cert_reqs is None else cert_reqs
|
|
|
|
if options is None:
|
|
options = 0
|
|
# SSLv2 is easily broken and is considered harmful and dangerous
|
|
options |= OP_NO_SSLv2
|
|
# SSLv3 has several problems and is now dangerous
|
|
options |= OP_NO_SSLv3
|
|
# Disable compression to prevent CRIME attacks for OpenSSL 1.0+
|
|
# (issue #309)
|
|
options |= OP_NO_COMPRESSION
|
|
|
|
context.options |= options
|
|
|
|
if getattr(context, 'supports_set_ciphers', True): # Platform-specific: Python 2.6
|
|
context.set_ciphers(ciphers or DEFAULT_CIPHERS)
|
|
|
|
context.verify_mode = cert_reqs
|
|
if getattr(context, 'check_hostname', None) is not None: # Platform-specific: Python 3.2
|
|
# We do our own verification, including fingerprints and alternative
|
|
# hostnames. So disable it here
|
|
context.check_hostname = False
|
|
return context
|
|
|
|
|
|
def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None,
|
|
ca_certs=None, server_hostname=None,
|
|
ssl_version=None, ciphers=None, ssl_context=None,
|
|
ca_cert_dir=None):
|
|
"""
|
|
All arguments except for server_hostname, ssl_context, and ca_cert_dir have
|
|
the same meaning as they do when using :func:`ssl.wrap_socket`.
|
|
|
|
:param server_hostname:
|
|
When SNI is supported, the expected hostname of the certificate
|
|
:param ssl_context:
|
|
A pre-made :class:`SSLContext` object. If none is provided, one will
|
|
be created using :func:`create_urllib3_context`.
|
|
:param ciphers:
|
|
A string of ciphers we wish the client to support. This is not
|
|
supported on Python 2.6 as the ssl module does not support it.
|
|
:param ca_cert_dir:
|
|
A directory containing CA certificates in multiple separate files, as
|
|
supported by OpenSSL's -CApath flag or the capath argument to
|
|
SSLContext.load_verify_locations().
|
|
"""
|
|
context = ssl_context
|
|
if context is None:
|
|
# Note: This branch of code and all the variables in it are no longer
|
|
# used by urllib3 itself. We should consider deprecating and removing
|
|
# this code.
|
|
context = create_urllib3_context(ssl_version, cert_reqs,
|
|
ciphers=ciphers)
|
|
|
|
if ca_certs or ca_cert_dir:
|
|
try:
|
|
context.load_verify_locations(ca_certs, ca_cert_dir)
|
|
except IOError as e: # Platform-specific: Python 2.6, 2.7, 3.2
|
|
raise SSLError(e)
|
|
# Py33 raises FileNotFoundError which subclasses OSError
|
|
# These are not equivalent unless we check the errno attribute
|
|
except OSError as e: # Platform-specific: Python 3.3 and beyond
|
|
if e.errno == errno.ENOENT:
|
|
raise SSLError(e)
|
|
raise
|
|
elif getattr(context, 'load_default_certs', None) is not None:
|
|
# try to load OS default certs; works well on Windows (require Python3.4+)
|
|
context.load_default_certs()
|
|
|
|
if certfile:
|
|
context.load_cert_chain(certfile, keyfile)
|
|
if HAS_SNI: # Platform-specific: OpenSSL with enabled SNI
|
|
return context.wrap_socket(sock, server_hostname=server_hostname)
|
|
|
|
warnings.warn(
|
|
'An HTTPS request has been made, but the SNI (Subject Name '
|
|
'Indication) extension to TLS is not available on this platform. '
|
|
'This may cause the server to present an incorrect TLS '
|
|
'certificate, which can cause validation failures. You can upgrade to '
|
|
'a newer version of Python to solve this. For more information, see '
|
|
'https://urllib3.readthedocs.io/en/latest/advanced-usage.html'
|
|
'#ssl-warnings',
|
|
SNIMissingWarning
|
|
)
|
|
return context.wrap_socket(sock)
|