diff --git a/Lib/ssl.py b/Lib/ssl.py index 1f3a31a..b54a684 100644 --- a/Lib/ssl.py +++ b/Lib/ssl.py @@ -116,6 +116,7 @@ except ImportError: from _ssl import HAS_SNI, HAS_ECDH, HAS_NPN, HAS_ALPN, HAS_TLSv1_3 +from _ssl import _DEFAULT_CIPHERS from _ssl import _OPENSSL_API_VERSION @@ -174,48 +175,7 @@ else: CHANNEL_BINDING_TYPES = [] -# Disable weak or insecure ciphers by default -# (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 -# * Prefer AES-GCM over ChaCha20 because most platforms have AES-NI -# (ChaCha20 needs OpenSSL 1.1.0 or patched 1.0.2) -# * Prefer any AES-GCM and ChaCha20 over any AES-CBC for better -# performance and security -# * Then Use HIGH cipher suites as a fallback -# * 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' - ) - -# 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 -# * Prefer AES-GCM over ChaCha20 because most platforms have AES-NI -# * Prefer any AES-GCM and ChaCha20 over any AES-CBC for better -# performance and security -# * Then Use HIGH cipher suites as a fallback -# * 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' -) +_RESTRICTED_SERVER_CIPHERS = _DEFAULT_CIPHERS class CertificateError(ValueError): @@ -389,8 +349,6 @@ class SSLContext(_SSLContext): def __new__(cls, protocol=PROTOCOL_TLS, *args, **kwargs): self = _SSLContext.__new__(cls, protocol) - if protocol != _SSLv2_IF_EXISTS: - self.set_ciphers(_DEFAULT_CIPHERS) return self def __init__(self, protocol=PROTOCOL_TLS): @@ -505,8 +463,6 @@ def create_default_context(purpose=Purpose.SERVER_AUTH, *, cafile=None, # verify certs and host name in client mode context.verify_mode = CERT_REQUIRED context.check_hostname = True - elif purpose == Purpose.CLIENT_AUTH: - context.set_ciphers(_RESTRICTED_SERVER_CIPHERS) if cafile or capath or cadata: context.load_verify_locations(cafile, capath, cadata) diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py index 54644e1..799100c 100644 --- a/Lib/test/test_ssl.py +++ b/Lib/test/test_ssl.py @@ -18,6 +18,7 @@ import asyncore import weakref import platform import functools +import sysconfig try: import ctypes except ImportError: @@ -36,7 +37,7 @@ PROTOCOLS = sorted(ssl._PROTOCOL_NAMES) HOST = support.HOST IS_LIBRESSL = ssl.OPENSSL_VERSION.startswith('LibreSSL') IS_OPENSSL_1_1 = not IS_LIBRESSL and ssl.OPENSSL_VERSION_INFO >= (1, 1, 0) - +PY_SSL_DEFAULT_CIPHERS = sysconfig.get_config_var('PY_SSL_DEFAULT_CIPHERS') def data_file(*name): return os.path.join(os.path.dirname(__file__), *name) @@ -889,6 +890,19 @@ class ContextTests(unittest.TestCase): with self.assertRaisesRegex(ssl.SSLError, "No cipher can be selected"): ctx.set_ciphers("^$:,;?*'dorothyx") + @unittest.skipUnless(PY_SSL_DEFAULT_CIPHERS == 1, + "Test applies only to Python default ciphers") + def test_python_ciphers(self): + ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT) + ciphers = ctx.get_ciphers() + for suite in ciphers: + name = suite['name'] + self.assertNotIn("PSK", name) + self.assertNotIn("SRP", name) + self.assertNotIn("MD5", name) + self.assertNotIn("RC4", name) + self.assertNotIn("3DES", name) + @unittest.skipIf(ssl.OPENSSL_VERSION_INFO < (1, 0, 2, 0, 0), 'OpenSSL too old') def test_get_ciphers(self): ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1) diff --git a/Modules/_ssl.c b/Modules/_ssl.c index df8c6a7..e23a569 100644 --- a/Modules/_ssl.c +++ b/Modules/_ssl.c @@ -206,6 +206,31 @@ SSL_SESSION_get_ticket_lifetime_hint(const SSL_SESSION *s) #endif /* OpenSSL < 1.1.0 or LibreSSL */ +/* Default cipher suites */ +#ifndef PY_SSL_DEFAULT_CIPHERS +#define PY_SSL_DEFAULT_CIPHERS 1 +#endif + +#if PY_SSL_DEFAULT_CIPHERS == 0 + #ifndef PY_SSL_DEFAULT_CIPHER_STRING + #error "Py_SSL_DEFAULT_CIPHERS 0 needs Py_SSL_DEFAULT_CIPHER_STRING" + #endif +#elif PY_SSL_DEFAULT_CIPHERS == 1 +/* Python custom selection of sensible ciper suites + * DEFAULT: OpenSSL's default cipher list. Since 1.0.2 the list is in sensible order. + * !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 + */ + #define PY_SSL_DEFAULT_CIPHER_STRING "DEFAULT:!aNULL:!eNULL:!MD5:!3DES:!DES:!RC4:!IDEA:!SEED:!aDSS:!SRP:!PSK" +#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 +#else + #error "Unsupported PY_SSL_DEFAULT_CIPHERS" +#endif + enum py_ssl_error { /* these mirror ssl.h */ @@ -2739,7 +2764,12 @@ _ssl__SSLContext_impl(PyTypeObject *type, int proto_version) /* A bare minimum cipher list without completely broken cipher suites. * It's far from perfect but gives users a better head start. */ if (proto_version != PY_SSL_VERSION_SSL2) { - result = SSL_CTX_set_cipher_list(ctx, "HIGH:!aNULL:!eNULL:!MD5"); +#if PY_SSL_DEFAULT_CIPHERS == 2 + /* stick to OpenSSL's default settings */ + result = 1; +#else + result = SSL_CTX_set_cipher_list(ctx, PY_SSL_DEFAULT_CIPHER_STRING); +#endif } else { /* SSLv2 needs MD5 */ result = SSL_CTX_set_cipher_list(ctx, "HIGH:!aNULL:!eNULL"); @@ -5279,6 +5309,9 @@ PyInit__ssl(void) (PyObject *)&PySSLSession_Type) != 0) return NULL; + PyModule_AddStringConstant(m, "_DEFAULT_CIPHERS", + PY_SSL_DEFAULT_CIPHER_STRING); + PyModule_AddIntConstant(m, "SSL_ERROR_ZERO_RETURN", PY_SSL_ERROR_ZERO_RETURN); PyModule_AddIntConstant(m, "SSL_ERROR_WANT_READ", diff --git a/configure.ac b/configure.ac index 7ea62f8..4b42393 100644 --- a/configure.ac +++ b/configure.ac @@ -5555,6 +5555,42 @@ if test "$have_getrandom" = yes; then [Define to 1 if the getrandom() function is available]) fi +# ssl module default cipher suite string +AH_TEMPLATE(PY_SSL_DEFAULT_CIPHERS, + [Default cipher suites list for ssl module. + 1: Python's preferred selection, 2: leave OpenSSL defaults untouched, 0: custom string]) +AH_TEMPLATE(PY_SSL_DEFAULT_CIPHER_STRING, + [Cipher suite string for PY_SSL_DEFAULT_CIPHERS=0] +) +AC_MSG_CHECKING(for --with-ssl-default-suites) +AC_ARG_WITH(ssl-default-suites, + AS_HELP_STRING([--with-ssl-default-suites=@<:@python|openssl|STRING@:>@], + [Override default cipher suites string, + python: use Python's preferred selection (default), + openssl: leave OpenSSL's defaults untouched, + STRING: use a custom string, + PROTOCOL_SSLv2 ignores the setting]), +[ +AC_MSG_RESULT($withval) +case "$withval" in + python) + AC_DEFINE(PY_SSL_DEFAULT_CIPHERS, 1) + ;; + openssl) + AC_DEFINE(PY_SSL_DEFAULT_CIPHERS, 2) + ;; + *) + AC_DEFINE(PY_SSL_DEFAULT_CIPHERS, 0) + AC_DEFINE_UNQUOTED(PY_SSL_DEFAULT_CIPHER_STRING, "$withval") + ;; +esac +], +[ +AC_MSG_RESULT(python) +AC_DEFINE(PY_SSL_DEFAULT_CIPHERS, 1) +]) + + # generate output files AC_CONFIG_FILES(Makefile.pre Modules/Setup.config Misc/python.pc Misc/python-config.sh) AC_CONFIG_FILES([Modules/ld_so_aix], [chmod +x Modules/ld_so_aix])