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bpo-31453: [WIP] Allow to change TLS protocols on Debian #3662

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bpo-31453: [WIP] Allow to change TLS protocols on Debian #3662

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4 changes: 4 additions & 0 deletions Misc/NEWS.d/next/Library/2017-09-19-21-06-23.bpo-31453.obElH-.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
Undo Debian Unstable's patching for SSL_CTX. Allow all protocols with
SSL_CTX_set_min_proto_version() again so they can be enabled and disabled
with SSL_CTX_set_options(). The set_min_proto_version is not supported by
Python, set_options is available as SSLContext.options.
28 changes: 28 additions & 0 deletions Modules/_ssl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2746,6 +2746,34 @@ _ssl__SSLContext_impl(PyTypeObject *type, int proto_version)
return NULL;
}

#ifdef SSL_CTX_set_min_proto_version
/* Workaround for Debian's OpenSSL patch
*
* Debian disables SSL 3.0, TLS 1.0, and TLS 1.1 by default. Python
* does not expose the new OpenSSL 1.1 API that is required to
* re-enable the old protocols. Documentation also promises that
* PROTOCOL_TLS has TLS 1.0 and 1.1 enabled and SSLv3 can be enabled
* by changing SSLContext.options.
*/
if ((proto_version == PY_SSL_VERSION_TLS) ||
(proto_version == PY_SSL_VERSION_TLS_CLIENT) ||
(proto_version == PY_SSL_VERSION_TLS_SERVER)) {
#if !defined(OPENSSL_NO_SSL3)
result = SSL_CTX_set_min_proto_version(ctx, SSL3_VERSION);
#elif !defined(OPENSSL_NO_TLS1)
result = SSL_CTX_set_min_proto_version(ctx, TLS1_VERSION);
#elif !defined(OPENSSL_NO_TLS1_1)
result = SSL_CTX_set_min_proto_version(ctx, TLS1_1_VERSION);
#else
result = 1;
#endif
if (result == 0) {
_setSSLError(NULL, 0, __FILE__, __LINE__);
return NULL;
}
}
#endif /* SSL_CTX_set_min_proto_version */

assert(type != NULL && type->tp_alloc != NULL);
self = (PySSLContext *) type->tp_alloc(type, 0);
if (self == NULL) {
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