bpo-32947: Fixes for TLS 1.3 and OpenSSL 1.1.1 (GH-8761)

Backport of TLS 1.3 related fixes from 3.7.

Misc fixes and workarounds for compatibility with OpenSSL 1.1.1 from git
master and TLS 1.3 support. With OpenSSL 1.1.1, Python negotiates TLS 1.3 by
default. Some test cases only apply to TLS 1.2.

OpenSSL 1.1.1 has added a new option OP_ENABLE_MIDDLEBOX_COMPAT for TLS
1.3. The feature is enabled by default for maximum compatibility with
broken middle boxes. Users should be able to disable the hack and CPython's test suite needs
it to verify default options

Signed-off-by: Christian Heimes <christian@python.org>

diff --git a/Doc/library/ssl.rst b/Doc/library/ssl.rst
index 25ecfaec2565f27fe7c321d4636ef4e124722890..e12cfc6af0ef3132cc6de1a312ca0f5d72550025 100644 (file)
--- a/Doc/library/ssl.rst
+++ b/Doc/library/ssl.rst
@@ -821,6 +821,15 @@ Constants
 
    .. versionadded:: 3.3
 
+.. data:: OP_ENABLE_MIDDLEBOX_COMPAT
+
+   Send dummy Change Cipher Spec (CCS) messages in TLS 1.3 handshake to make
+   a TLS 1.3 connection look more like a TLS 1.2 connection.
+
+   This option is only available with OpenSSL 1.1.1 and later.
+
+   .. versionadded:: 3.6.7
+
 .. data:: OP_NO_COMPRESSION
 
    Disable compression on the SSL channel.  This is useful if the application

diff --git a/Lib/test/test_asyncio/test_events.py b/Lib/test/test_asyncio/test_events.py
index 548a4610f7729e8c303d95b3589275e3f77f6670..bd62897b6a57245cc21f0b68478fcb9f77c3b69c 100644 (file)
--- a/Lib/test/test_asyncio/test_events.py
+++ b/Lib/test/test_asyncio/test_events.py
@@ -1187,7 +1187,11 @@ class EventLoopTestsMixin:
                     self.loop.run_until_complete(f_c)
 
         # close connection
-        proto.transport.close()
+        # transport may be None with TLS 1.3, because connection is
+        # interrupted, server is unable to send session tickets, and
+        # transport is closed.
+        if proto.transport is not None:
+            proto.transport.close()
         server.close()
 
     def test_legacy_create_server_ssl_match_failed(self):

diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 9785a59a7e49abe51b59d0da0e9e0205c06a19a4..6b3cd5b6e3760c3a51cceab029c6a95a76e6a5cb 100644 (file)
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -89,6 +89,7 @@ OP_NO_COMPRESSION = getattr(ssl, "OP_NO_COMPRESSION", 0)
 OP_SINGLE_DH_USE = getattr(ssl, "OP_SINGLE_DH_USE", 0)
 OP_SINGLE_ECDH_USE = getattr(ssl, "OP_SINGLE_ECDH_USE", 0)
 OP_CIPHER_SERVER_PREFERENCE = getattr(ssl, "OP_CIPHER_SERVER_PREFERENCE", 0)
+OP_ENABLE_MIDDLEBOX_COMPAT = getattr(ssl, "OP_ENABLE_MIDDLEBOX_COMPAT", 0)
 
 
 def handle_error(prefix):
@@ -181,8 +182,8 @@ class BasicSocketTests(unittest.TestCase):
         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
+        ssl.OP_NO_TLSv1_1
+        ssl.OP_NO_TLSv1_2
 
     def test_str_for_enums(self):
         # Make sure that the PROTOCOL_* constants have enum-like string
@@ -899,12 +900,13 @@ class ContextTests(unittest.TestCase):
 
     @skip_if_broken_ubuntu_ssl
     def test_options(self):
-        ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
+        ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
         # OP_ALL | OP_NO_SSLv2 | OP_NO_SSLv3 is the default value
         default = (ssl.OP_ALL | ssl.OP_NO_SSLv2 | ssl.OP_NO_SSLv3)
         # SSLContext also enables these by default
         default |= (OP_NO_COMPRESSION | OP_CIPHER_SERVER_PREFERENCE |
-                    OP_SINGLE_DH_USE | OP_SINGLE_ECDH_USE)
+                    OP_SINGLE_DH_USE | OP_SINGLE_ECDH_USE |
+                    OP_ENABLE_MIDDLEBOX_COMPAT)
         self.assertEqual(default, ctx.options)
         ctx.options |= ssl.OP_NO_TLSv1
         self.assertEqual(default | ssl.OP_NO_TLSv1, ctx.options)
@@ -1857,11 +1859,23 @@ if _have_threads:
                         self.sock, server_side=True)
                     self.server.selected_npn_protocols.append(self.sslconn.selected_npn_protocol())
                     self.server.selected_alpn_protocols.append(self.sslconn.selected_alpn_protocol())
-                except (ssl.SSLError, ConnectionResetError, OSError) as e:
+                except (ConnectionResetError, BrokenPipeError) as e:
                     # We treat ConnectionResetError as though it were an
                     # SSLError - OpenSSL on Ubuntu abruptly closes the
                     # connection when asked to use an unsupported protocol.
                     #
+                    # BrokenPipeError is raised in TLS 1.3 mode, when OpenSSL
+                    # tries to send session tickets after handshake.
+                    # https://github.com/openssl/openssl/issues/6342
+                    self.server.conn_errors.append(str(e))
+                    if self.server.chatty:
+                        handle_error(
+                            "\n server:  bad connection attempt from " + repr(
+                                self.addr) + ":\n")
+                    self.running = False
+                    self.close()
+                    return False
+                except (ssl.SSLError, OSError) as e:
                     # OSError may occur with wrong protocols, e.g. both
                     # sides use PROTOCOL_TLS_SERVER.
                     #
@@ -3042,7 +3056,7 @@ if _have_threads:
                 # Block on the accept and wait on the connection to close.
                 evt.set()
                 remote, peer = server.accept()
-                remote.recv(1)
+                remote.send(remote.recv(4))
 
             t = threading.Thread(target=serve)
             t.start()
@@ -3050,6 +3064,8 @@ if _have_threads:
             evt.wait()
             client = context.wrap_socket(socket.socket())
             client.connect((host, port))
+            client.send(b'data')
+            client.recv()
             client_addr = client.getsockname()
             client.close()
             t.join()

diff --git a/Misc/NEWS.d/next/Library/2018-08-14-08-57-01.bpo-32947.mqStVW.rst b/Misc/NEWS.d/next/Library/2018-08-14-08-57-01.bpo-32947.mqStVW.rst
new file mode 100644 (file)
index 0000000..28de360
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-08-14-08-57-01.bpo-32947.mqStVW.rst
@@ -0,0 +1,2 @@
+Add OP_ENABLE_MIDDLEBOX_COMPAT and test workaround for TLSv1.3 for future
+compatibility with OpenSSL 1.1.1.

diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 5e007da858bd591940b62e2a0b7d36e406e77b49..e0c7dfbdaacb2f6f252187a16a0876eb26202ca9 100644 (file)
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -5486,6 +5486,10 @@ PyInit__ssl(void)
     PyModule_AddIntConstant(m, "OP_NO_COMPRESSION",
                             SSL_OP_NO_COMPRESSION);
 #endif
+#ifdef SSL_OP_ENABLE_MIDDLEBOX_COMPAT
+    PyModule_AddIntConstant(m, "OP_ENABLE_MIDDLEBOX_COMPAT",
+                            SSL_OP_ENABLE_MIDDLEBOX_COMPAT);
+#endif
 
 #if HAVE_SNI
     r = Py_True;