From fb3b4db3b9f309172f583b24dcef6ca4901413cd Mon Sep 17 00:00:00 2001 From: Christian Heimes Date: Thu, 7 Sep 2017 18:07:00 -0700 Subject: [PATCH] [2.7] bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3 (GH-1363) * bpo-29136: Add TLS 1.3 support TLS 1.3 introduces a new, distinct set of cipher suites. The TLS 1.3 cipher suites don't overlap with cipher suites from TLS 1.2 and earlier. Since Python sets its own set of permitted ciphers, TLS 1.3 handshake will fail as soon as OpenSSL 1.1.1 is released. Let's enable the common AES-GCM and ChaCha20 suites. Additionally the flag OP_NO_TLSv1_3 is added. It defaults to 0 (no op) with OpenSSL prior to 1.1.1. This allows applications to opt-out from TLS 1.3 now. Signed-off-by: Christian Heimes . (cherry picked from commit cb5b68abdeb1b1d56c581d5b4d647018703d61e3) --- Doc/library/ssl.rst | 28 ++++++++++++++++++- Lib/ssl.py | 8 +++++- Lib/test/test_ssl.py | 25 +++++++++++++++++ .../2017-09-04-16-39-49.bpo-29136.vSn1oR.rst | 1 + Modules/_ssl.c | 13 +++++++++ 5 files changed, 73 insertions(+), 2 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2017-09-04-16-39-49.bpo-29136.vSn1oR.rst diff --git a/Doc/library/ssl.rst b/Doc/library/ssl.rst index 36beb1777cf036..288b2914a25c1f 100644 --- a/Doc/library/ssl.rst +++ b/Doc/library/ssl.rst @@ -192,12 +192,17 @@ instead. ------------------------ --------- --------- ---------- --------- ----------- ----------- *SSLv2* yes no yes no no no *SSLv3* no yes yes no no no - *SSLv23* no yes yes yes yes yes + *SSLv23* [1]_ no yes yes yes yes yes *TLSv1* no no yes yes no no *TLSv1.1* no no yes no yes no *TLSv1.2* no no yes no no yes ======================== ========= ========= ========== ========= =========== =========== + .. rubric:: Footnotes + .. [1] TLS 1.3 protocol will be available with :data:`PROTOCOL_SSLv23` in + OpenSSL >= 1.1.1. There is no dedicated PROTOCOL constant for just + TLS 1.3. + .. note:: Which connections succeed will vary depending on the version of @@ -286,6 +291,11 @@ purposes. 3DES was dropped from the default cipher string. + .. versionchanged:: 2.7.15 + + TLS 1.3 cipher suites TLS_AES_128_GCM_SHA256, TLS_AES_256_GCM_SHA384, + and TLS_CHACHA20_POLY1305_SHA256 were added to the default cipher string. + .. function:: _https_verify_certificates(enable=True) Specifies whether or not server certificates are verified when creating @@ -701,6 +711,16 @@ Constants .. versionadded:: 2.7.9 +.. data:: OP_NO_TLSv1_3 + + Prevents a TLSv1.3 connection. This option is only applicable in conjunction + with :const:`PROTOCOL_TLS`. It prevents the peers from choosing TLSv1.3 as + the protocol version. TLS 1.3 is available with OpenSSL 1.1.1 or later. + When Python has been compiled against an older version of OpenSSL, the + flag defaults to *0*. + + .. versionadded:: 2.7.15 + .. data:: OP_CIPHER_SERVER_PREFERENCE Use the server's cipher ordering preference, rather than the client's. @@ -765,6 +785,12 @@ Constants .. versionadded:: 2.7.9 +.. data:: HAS_TLSv1_3 + + Whether the OpenSSL library has built-in support for the TLS 1.3 protocol. + + .. versionadded:: 2.7.15 + .. data:: CHANNEL_BINDING_TYPES List of supported TLS channel binding types. Strings in this list diff --git a/Lib/ssl.py b/Lib/ssl.py index f28c863811fd98..22d478b56871b4 100644 --- a/Lib/ssl.py +++ b/Lib/ssl.py @@ -123,7 +123,7 @@ def _import_symbols(prefix): _import_symbols('PROTOCOL_') _import_symbols('VERIFY_') -from _ssl import HAS_SNI, HAS_ECDH, HAS_NPN, HAS_ALPN +from _ssl import HAS_SNI, HAS_ECDH, HAS_NPN, HAS_ALPN, HAS_TLSv1_3 from _ssl import _OPENSSL_API_VERSION @@ -157,6 +157,7 @@ def _import_symbols(prefix): # (OpenSSL's default setting is 'DEFAULT:!aNULL:!eNULL') # Enable a better set of ciphers by default # This list has been explicitly chosen to: +# * TLS 1.3 ChaCha20 and AES-GCM cipher suites # * Prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE) # * Prefer ECDHE over DHE for better performance # * Prefer AEAD over CBC for better performance and security @@ -168,6 +169,8 @@ def _import_symbols(prefix): # * Disable NULL authentication, NULL encryption, 3DES and MD5 MACs # for security reasons _DEFAULT_CIPHERS = ( + '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:ECDH+HIGH:DH+HIGH:RSA+AESGCM:RSA+AES:RSA+HIGH:' '!aNULL:!eNULL:!MD5:!3DES' @@ -175,6 +178,7 @@ def _import_symbols(prefix): # Restricted and more secure ciphers for the server side # This list has been explicitly chosen to: +# * TLS 1.3 ChaCha20 and AES-GCM cipher suites # * Prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE) # * Prefer ECDHE over DHE for better performance # * Prefer AEAD over CBC for better performance and security @@ -185,6 +189,8 @@ def _import_symbols(prefix): # * Disable NULL authentication, NULL encryption, MD5 MACs, DSS, RC4, and # 3DES for security reasons _RESTRICTED_SERVER_CIPHERS = ( + '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:ECDH+HIGH:DH+HIGH:RSA+AESGCM:RSA+AES:RSA+HIGH:' '!aNULL:!eNULL:!MD5:!DSS:!RC4:!3DES' diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py index d9ef232580c123..cfc03e343c7d6b 100644 --- a/Lib/test/test_ssl.py +++ b/Lib/test/test_ssl.py @@ -168,6 +168,13 @@ def test_constants(self): ssl.OP_NO_COMPRESSION self.assertIn(ssl.HAS_SNI, {True, False}) self.assertIn(ssl.HAS_ECDH, {True, False}) + ssl.OP_NO_SSLv2 + ssl.OP_NO_SSLv3 + ssl.OP_NO_TLSv1 + ssl.OP_NO_TLSv1_3 + if ssl.OPENSSL_VERSION_INFO >= (1, 0, 1): + ssl.OP_NO_TLSv1_1 + ssl.OP_NO_TLSv1_2 def test_random(self): v = ssl.RAND_status() @@ -2784,6 +2791,24 @@ def test_version_basic(self): self.assertEqual(s.version(), 'TLSv1') self.assertIs(s.version(), None) + @unittest.skipUnless(ssl.HAS_TLSv1_3, + "test requires TLSv1.3 enabled OpenSSL") + def test_tls1_3(self): + context = ssl.SSLContext(ssl.PROTOCOL_TLS) + context.load_cert_chain(CERTFILE) + # disable all but TLS 1.3 + context.options |= ( + ssl.OP_NO_TLSv1 | ssl.OP_NO_TLSv1_1 | ssl.OP_NO_TLSv1_2 + ) + with ThreadedEchoServer(context=context) as server: + with context.wrap_socket(socket.socket()) as s: + s.connect((HOST, server.port)) + self.assertIn(s.cipher()[0], [ + 'TLS13-AES-256-GCM-SHA384', + 'TLS13-CHACHA20-POLY1305-SHA256', + 'TLS13-AES-128-GCM-SHA256', + ]) + @unittest.skipUnless(ssl.HAS_ECDH, "test requires ECDH-enabled OpenSSL") def test_default_ecdh_curve(self): # Issue #21015: elliptic curve-based Diffie Hellman key exchange diff --git a/Misc/NEWS.d/next/Library/2017-09-04-16-39-49.bpo-29136.vSn1oR.rst b/Misc/NEWS.d/next/Library/2017-09-04-16-39-49.bpo-29136.vSn1oR.rst new file mode 100644 index 00000000000000..e76997ef836128 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2017-09-04-16-39-49.bpo-29136.vSn1oR.rst @@ -0,0 +1 @@ +Add TLS 1.3 cipher suites and OP_NO_TLSv1_3. diff --git a/Modules/_ssl.c b/Modules/_ssl.c index 5b4cec203addf6..f70af266731ad0 100644 --- a/Modules/_ssl.c +++ b/Modules/_ssl.c @@ -4281,6 +4281,11 @@ init_ssl(void) #if HAVE_TLSv1_2 PyModule_AddIntConstant(m, "OP_NO_TLSv1_1", SSL_OP_NO_TLSv1_1); PyModule_AddIntConstant(m, "OP_NO_TLSv1_2", SSL_OP_NO_TLSv1_2); +#endif +#ifdef SSL_OP_NO_TLSv1_3 + PyModule_AddIntConstant(m, "OP_NO_TLSv1_3", SSL_OP_NO_TLSv1_3); +#else + PyModule_AddIntConstant(m, "OP_NO_TLSv1_3", 0); #endif PyModule_AddIntConstant(m, "OP_CIPHER_SERVER_PREFERENCE", SSL_OP_CIPHER_SERVER_PREFERENCE); @@ -4333,6 +4338,14 @@ init_ssl(void) Py_INCREF(r); PyModule_AddObject(m, "HAS_ALPN", r); +#if defined(TLS1_3_VERSION) && !defined(OPENSSL_NO_TLS1_3) + r = Py_True; +#else + r = Py_False; +#endif + Py_INCREF(r); + PyModule_AddObject(m, "HAS_TLSv1_3", r); + /* Mappings for error codes */ err_codes_to_names = PyDict_New(); err_names_to_codes = PyDict_New();