From e8bf04de4ba045029aa8964126d8cdd2d7c282a6 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Tue, 19 Feb 2019 09:24:16 -0800
Subject: [PATCH] bpo-36037: Fix test_ssl for strict OpenSSL policy (GH-11940)

Fix test_ssl for strict OpenSSL configuration like RHEL8 strict crypto policy.
Use older TLS version for minimum TLS version of the server SSL context if
needed, to test TLS version older than default minimum TLS version.
(cherry picked from commit 3ef6344ee53f59ee86831ec36ed2c6f93a56229d)

Co-authored-by: Victor Stinner <vstinner@redhat.com>
---
 Lib/test/test_ssl.py                          | 30 ++++++++++++++++++-
 .../2019-02-19-15-21-14.bpo-36037.75wG9_.rst  |  3 ++
 2 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Tests/2019-02-19-15-21-14.bpo-36037.75wG9_.rst

diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 38ecddd07d98c0..8eab447415f791 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -34,6 +34,19 @@
 IS_OPENSSL_1_1_1 = not IS_LIBRESSL and ssl.OPENSSL_VERSION_INFO >= (1, 1, 1)
 PY_SSL_DEFAULT_CIPHERS = sysconfig.get_config_var('PY_SSL_DEFAULT_CIPHERS')
 
+PROTOCOL_TO_TLS_VERSION = {}
+for proto, ver in (
+    ("PROTOCOL_SSLv23", "SSLv3"),
+    ("PROTOCOL_TLSv1", "TLSv1"),
+    ("PROTOCOL_TLSv1_1", "TLSv1_1"),
+):
+    try:
+        proto = getattr(ssl, proto)
+        ver = getattr(ssl.TLSVersion, ver)
+    except AttributeError:
+        continue
+    PROTOCOL_TO_TLS_VERSION[proto] = ver
+
 def data_file(*name):
     return os.path.join(os.path.dirname(__file__), *name)
 
@@ -1112,7 +1125,11 @@ def test_min_max_version(self):
         # Fedora override the setting to TLS 1.0.
         self.assertIn(
             ctx.minimum_version,
-            {ssl.TLSVersion.MINIMUM_SUPPORTED, ssl.TLSVersion.TLSv1}
+            {ssl.TLSVersion.MINIMUM_SUPPORTED,
+             # Fedora 29 uses TLS 1.0 by default
+             ssl.TLSVersion.TLSv1,
+             # RHEL 8 uses TLS 1.2 by default
+             ssl.TLSVersion.TLSv1_2}
         )
         self.assertEqual(
             ctx.maximum_version, ssl.TLSVersion.MAXIMUM_SUPPORTED
@@ -2630,6 +2647,17 @@ def try_protocol_combo(server_protocol, client_protocol, expect_success,
     server_context = ssl.SSLContext(server_protocol)
     server_context.options |= server_options
 
+    min_version = PROTOCOL_TO_TLS_VERSION.get(client_protocol, None)
+    if (min_version is not None
+    # SSLContext.minimum_version is only available on recent OpenSSL
+    # (setter added in OpenSSL 1.1.0, getter added in OpenSSL 1.1.1)
+    and hasattr(server_context, 'minimum_version')
+    and server_protocol == ssl.PROTOCOL_TLS
+    and server_context.minimum_version > min_version):
+        # If OpenSSL configuration is strict and requires more recent TLS
+        # version, we have to change the minimum to test old TLS versions.
+        server_context.minimum_version = min_version
+
     # NOTE: we must enable "ALL" ciphers on the client, otherwise an
     # SSLv23 client will send an SSLv3 hello (rather than SSLv2)
     # starting from OpenSSL 1.0.0 (see issue #8322).
diff --git a/Misc/NEWS.d/next/Tests/2019-02-19-15-21-14.bpo-36037.75wG9_.rst b/Misc/NEWS.d/next/Tests/2019-02-19-15-21-14.bpo-36037.75wG9_.rst
new file mode 100644
index 00000000000000..dbc0fa256e027f
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2019-02-19-15-21-14.bpo-36037.75wG9_.rst
@@ -0,0 +1,3 @@
+Fix test_ssl for strict OpenSSL configuration like RHEL8 strict crypto policy.
+Use older TLS version for minimum TLS version of the server SSL context if
+needed, to test TLS version older than default minimum TLS version.