diff options
Diffstat (limited to 'urllib3/util/ssl_.py')
| -rw-r--r-- | urllib3/util/ssl_.py | 58 |
1 files changed, 42 insertions, 16 deletions
diff --git a/urllib3/util/ssl_.py b/urllib3/util/ssl_.py index a788b1b..b846d42 100644 --- a/urllib3/util/ssl_.py +++ b/urllib3/util/ssl_.py @@ -1,7 +1,7 @@ from binascii import hexlify, unhexlify -from hashlib import md5, sha1 +from hashlib import md5, sha1, sha256 -from ..exceptions import SSLError +from ..exceptions import SSLError, InsecurePlatformWarning SSLContext = None @@ -9,9 +9,10 @@ HAS_SNI = False create_default_context = None import errno -import ssl +import warnings 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: @@ -24,14 +25,24 @@ except ImportError: OP_NO_SSLv2, OP_NO_SSLv3 = 0x1000000, 0x2000000 OP_NO_COMPRESSION = 0x20000 -try: - from ssl import _DEFAULT_CIPHERS -except ImportError: - _DEFAULT_CIPHERS = ( - 'ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+HIGH:' - 'DH+HIGH:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+HIGH:RSA+3DES:ECDH+RC4:' - 'DH+RC4:RSA+RC4:!aNULL:!eNULL:!MD5' - ) +# 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 cipher suites that offer perfect forward secrecy (DHE/ECDHE), +# - prefer ECDHE over DHE for better performance, +# - prefer any AES-GCM over any AES-CBC for better performance and security, +# - use 3DES as fallback which is secure but slow, +# - disable NULL authentication, MD5 MACs and DSS for security reasons. +DEFAULT_CIPHERS = ( + 'ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+HIGH:' + 'DH+HIGH:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+HIGH:RSA+3DES:!aNULL:' + '!eNULL:!MD5' +) try: from ssl import SSLContext # Modern SSL? @@ -39,7 +50,8 @@ except ImportError: import sys class SSLContext(object): # Platform-specific: Python 2 & 3.1 - supports_set_ciphers = sys.version_info >= (2, 7) + supports_set_ciphers = ((2, 7) <= sys.version_info < (3,) or + (3, 2) <= sys.version_info) def __init__(self, protocol_version): self.protocol = protocol_version @@ -69,6 +81,14 @@ except ImportError: self.ciphers = cipher_suite def wrap_socket(self, socket, server_hostname=None): + warnings.warn( + 'A true SSLContext object is not available. This prevents ' + 'urllib3 from configuring SSL appropriately and may cause ' + 'certain SSL connections to fail. For more information, see ' + 'https://urllib3.readthedocs.org/en/latest/security.html' + '#insecureplatformwarning.', + InsecurePlatformWarning + ) kwargs = { 'keyfile': self.keyfile, 'certfile': self.certfile, @@ -96,7 +116,8 @@ def assert_fingerprint(cert, fingerprint): # this digest. hashfunc_map = { 16: md5, - 20: sha1 + 20: sha1, + 32: sha256, } fingerprint = fingerprint.replace(':', '').lower() @@ -157,7 +178,7 @@ def resolve_ssl_version(candidate): return candidate -def create_urllib3_context(ssl_version=None, cert_reqs=ssl.CERT_REQUIRED, +def create_urllib3_context(ssl_version=None, cert_reqs=None, options=None, ciphers=None): """All arguments have the same meaning as ``ssl_wrap_socket``. @@ -194,6 +215,9 @@ def create_urllib3_context(ssl_version=None, cert_reqs=ssl.CERT_REQUIRED, """ 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 @@ -207,11 +231,13 @@ def create_urllib3_context(ssl_version=None, cert_reqs=ssl.CERT_REQUIRED, context.options |= options if getattr(context, 'supports_set_ciphers', True): # Platform-specific: Python 2.6 - context.set_ciphers(ciphers or _DEFAULT_CIPHERS) + 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 - context.check_hostname = (context.verify_mode == ssl.CERT_REQUIRED) + # We do our own verification, including fingerprints and alternative + # hostnames. So disable it here + context.check_hostname = False return context |