diff options
| -rw-r--r-- | Doc/library/ssl.rst | 8 | ||||
| -rw-r--r-- | Lib/test/test_nntplib.py | 24 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Security/2021-05-01-13-13-40.bpo-43998.xhmWD7.rst | 5 | ||||
| -rw-r--r-- | Modules/_ssl.c | 43 |
4 files changed, 72 insertions, 8 deletions
diff --git a/Doc/library/ssl.rst b/Doc/library/ssl.rst index a58717c3ab..f1c43ee3d8 100644 --- a/Doc/library/ssl.rst +++ b/Doc/library/ssl.rst @@ -1471,6 +1471,14 @@ to speed up repeated connections from the same clients. ciphers, no ``NULL`` ciphers and no ``MD5`` ciphers (except for :data:`PROTOCOL_SSLv2`). + .. versionchanged:: 3.9.5_p2 (Gentoo) + + The default cipher suites now include only secure AES and ChaCha20 + ciphers with forward secrecy and security level 2. RSA and DH keys with + less than 2048 bits and ECC keys with less than 224 bits are prohibited. + :data:`PROTOCOL_TLS`, :data:`PROTOCOL_TLS_CLIENT`, and + :data:`PROTOCOL_TLS_SERVER` use TLS 1.2 as minimum TLS version. + :class:`SSLContext` objects have the following methods and attributes: diff --git a/Lib/test/test_nntplib.py b/Lib/test/test_nntplib.py index 89a2004dfb..d27e4abae8 100644 --- a/Lib/test/test_nntplib.py +++ b/Lib/test/test_nntplib.py @@ -37,6 +37,8 @@ else: class NetworkedNNTPTestsMixin: + ssl_context = None + def test_welcome(self): welcome = self.server.getwelcome() self.assertEqual(str, type(welcome)) @@ -269,6 +271,13 @@ class NetworkedNNTPTestsMixin: return False return True + kwargs = dict( + timeout=support.INTERNET_TIMEOUT, + usenetrc=False + ) + if self.ssl_context is not None: + kwargs["ssl_context"] = self.ssl_context + try: with self.NNTP_CLASS(self.NNTP_HOST, timeout=TIMEOUT, usenetrc=False) as server: self.assertTrue(is_connected()) @@ -306,15 +315,21 @@ class NetworkedNNTPTests(NetworkedNNTPTestsMixin, unittest.TestCase): @classmethod def setUpClass(cls): support.requires("network") - with support.transient_internet(cls.NNTP_HOST): + kwargs = dict( + timeout=support.INTERNET_TIMEOUT, + usenetrc=False + ) + if cls.ssl_context is not None: + kwargs["ssl_context"] = cls.ssl_context + with socket_helper.transient_internet(cls.NNTP_HOST): try: - cls.server = cls.NNTP_CLASS(cls.NNTP_HOST, timeout=TIMEOUT, - usenetrc=False) + cls.server = cls.NNTP_CLASS(cls.NNTP_HOST, **kwargs) except SSLError as ssl_err: # matches "[SSL: DH_KEY_TOO_SMALL] dh key too small" if re.search(r'(?i)KEY.TOO.SMALL', ssl_err.reason): raise unittest.SkipTest(f"{cls} got {ssl_err} connecting " f"to {cls.NNTP_HOST!r}") + print(cls.NNTP_HOST) raise except EOF_ERRORS: raise unittest.SkipTest(f"{cls} got EOF error on connecting " @@ -347,6 +362,9 @@ class NetworkedNNTP_SSLTests(NetworkedNNTPTests): # Disabled as the connection will already be encrypted. test_starttls = None + ssl_context = ssl._create_unverified_context() + ssl_context.set_ciphers("DEFAULT") + ssl_context.maximum_version = ssl.TLSVersion.TLSv1_2 # # Non-networked tests using a local server (or something mocking it). diff --git a/Misc/NEWS.d/next/Security/2021-05-01-13-13-40.bpo-43998.xhmWD7.rst b/Misc/NEWS.d/next/Security/2021-05-01-13-13-40.bpo-43998.xhmWD7.rst new file mode 100644 index 0000000000..6a40346128 --- /dev/null +++ b/Misc/NEWS.d/next/Security/2021-05-01-13-13-40.bpo-43998.xhmWD7.rst @@ -0,0 +1,5 @@ +The :mod:`ssl` module sets more secure cipher suites defaults. Ciphers +without forward secrecy and with SHA-1 MAC are disabled by default. Security +level 2 prohibits weak RSA, DH, and ECC keys with less than 112 bits of +security. :class:`~ssl.SSLContext` defaults to minimum protocol version TLS +1.2. Settings are based on Hynek Schlawack's research. diff --git a/Modules/_ssl.c b/Modules/_ssl.c index bc665db0d5..01a2067596 100644 --- a/Modules/_ssl.c +++ b/Modules/_ssl.c @@ -300,15 +300,27 @@ SSL_SESSION_get_ticket_lifetime_hint(const SSL_SESSION *s) #ifndef PY_SSL_DEFAULT_CIPHER_STRING #error "Py_SSL_DEFAULT_CIPHERS 0 needs Py_SSL_DEFAULT_CIPHER_STRING" #endif + #ifndef PY_SSL_MIN_PROTOCOL + #define PY_SSL_MIN_PROTOCOL TLS1_2_VERSION + #endif #elif PY_SSL_DEFAULT_CIPHERS == 1 /* Python custom selection of sensible cipher suites - * DEFAULT: OpenSSL's default cipher list. Since 1.0.2 the list is in sensible order. + * @SECLEVEL=2: security level 2 with 112 bits minimum security (e.g. 2048 bits RSA key) + * ECDH+*: enable ephemeral elliptic curve Diffie-Hellman + * DHE+*: fallback to ephemeral finite field Diffie-Hellman + * encryption order: AES AEAD (GCM), ChaCha AEAD, AES CBC * !aNULL:!eNULL: really no NULL ciphers - * !MD5:!3DES:!DES:!RC4:!IDEA:!SEED: no weak or broken algorithms on old OpenSSL versions. * !aDSS: no authentication with discrete logarithm DSA algorithm - * !SRP:!PSK: no secure remote password or pre-shared key authentication + * !SHA1: no weak SHA1 MAC + * !AESCCM: no CCM mode, it's uncommon and slow + * + * Based on Hynek's excellent blog post (update 2021-02-11) + * https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/ */ - #define PY_SSL_DEFAULT_CIPHER_STRING "DEFAULT:!aNULL:!eNULL:!MD5:!3DES:!DES:!RC4:!IDEA:!SEED:!aDSS:!SRP:!PSK" + #define PY_SSL_DEFAULT_CIPHER_STRING "@SECLEVEL=2:ECDH+AESGCM:ECDH+CHACHA20:ECDH+AES:DHE+AES:!aNULL:!eNULL:!aDSS:!SHA1:!AESCCM" + #ifndef PY_SSL_MIN_PROTOCOL + #define PY_SSL_MIN_PROTOCOL TLS1_2_VERSION + #endif #elif PY_SSL_DEFAULT_CIPHERS == 2 /* Ignored in SSLContext constructor, only used to as _ssl.DEFAULT_CIPHER_STRING */ #define PY_SSL_DEFAULT_CIPHER_STRING SSL_DEFAULT_CIPHER_LIST @@ -3249,8 +3261,25 @@ _ssl__SSLContext_impl(PyTypeObject *type, int proto_version) ERR_clear_error(); PyErr_SetString(PySSLErrorObject, "No cipher can be selected."); - return NULL; + goto error; + } +#ifdef PY_SSL_MIN_PROTOCOL + switch(proto_version) { + case PY_SSL_VERSION_TLS: + case PY_SSL_VERSION_TLS_CLIENT: + case PY_SSL_VERSION_TLS_SERVER: + result = SSL_CTX_set_min_proto_version(ctx, PY_SSL_MIN_PROTOCOL); + if (result == 0) { + PyErr_Format(PyExc_ValueError, + "Failed to set minimum protocol 0x%x", + PY_SSL_MIN_PROTOCOL); + goto error; + } + break; + default: + break; } +#endif #if defined(SSL_MODE_RELEASE_BUFFERS) /* Set SSL_MODE_RELEASE_BUFFERS. This potentially greatly reduces memory @@ -3303,6 +3332,10 @@ _ssl__SSLContext_impl(PyTypeObject *type, int proto_version) #endif return (PyObject *)self; + error: + Py_XDECREF(self); + ERR_clear_error(); + return NULL; } static int |