Issue #19422: Explicitly disallow non-SOCK_STREAM sockets in the ssl module,...

Issue #19422: Explicitly disallow non-SOCK_STREAM sockets in the ssl module, rather than silently let them emit clear text data.

Doc/library/ssl.rst

@@ -69,13 +69,16 @@ Functions, Constants, and Exceptions
 
    Takes an instance ``sock`` of :class:`socket.socket`, and returns an instance
    of :class:`ssl.SSLSocket`, a subtype of :class:`socket.socket`, which wraps
-   the underlying socket in an SSL context.  For client-side sockets, the
-   context construction is lazy; if the underlying socket isn't connected yet,
-   the context construction will be performed after :meth:`connect` is called on
-   the socket.  For server-side sockets, if the socket has no remote peer, it is
-   assumed to be a listening socket, and the server-side SSL wrapping is
-   automatically performed on client connections accepted via the :meth:`accept`
-   method.  :func:`wrap_socket` may raise :exc:`SSLError`.
+   the underlying socket in an SSL context.  ``sock`` must be a
+   :data:`~socket.SOCK_STREAM` socket; other socket types are unsupported.
+
+   For client-side sockets, the context construction is lazy; if the
+   underlying socket isn't connected yet, the context construction will be
+   performed after :meth:`connect` is called on the socket.  For
+   server-side sockets, if the socket has no remote peer, it is assumed
+   to be a listening socket, and the server-side SSL wrapping is
+   automatically performed on client connections accepted via the
+   :meth:`accept` method.  :func:`wrap_socket` may raise :exc:`SSLError`.
 
    The ``keyfile`` and ``certfile`` parameters specify optional files which
    contain a certificate to be used to identify the local side of the

Lib/ssl.py

@@ -89,6 +89,7 @@ else:
 
 from socket import socket, _fileobject, _delegate_methods, error as socket_error
 from socket import getnameinfo as _getnameinfo
+from socket import SOL_SOCKET, SO_TYPE, SOCK_STREAM
 import base64        # for DER-to-PEM translation
 import errno
 
@@ -108,6 +109,10 @@ class SSLSocket(socket):
                  ssl_version=PROTOCOL_SSLv23, ca_certs=None,
                  do_handshake_on_connect=True,
                  suppress_ragged_eofs=True, ciphers=None):
+        # Can't use sock.type as other flags (such as SOCK_NONBLOCK) get
+        # mixed in.
+        if sock.getsockopt(SOL_SOCKET, SO_TYPE) != SOCK_STREAM:
+            raise NotImplementedError("only stream sockets are supported")
         socket.__init__(self, _sock=sock._sock)
         # The initializer for socket overrides the methods send(), recv(), etc.
         # in the instancce, which we don't need -- but we want to provide the

Lib/test/test_ssl.py

@@ -232,6 +232,13 @@ class BasicSocketTests(unittest.TestCase):
         self.assertRaises(socket.error, ss.send, b'x')
         self.assertRaises(socket.error, ss.sendto, b'x', ('0.0.0.0', 0))
 
+    def test_unsupported_dtls(self):
+        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        self.addCleanup(s.close)
+        with self.assertRaises(NotImplementedError) as cx:
+            ssl.wrap_socket(s, cert_reqs=ssl.CERT_NONE)
+        self.assertEqual(str(cx.exception), "only stream sockets are supported")
+
 
 class NetworkedTests(unittest.TestCase):
 

Misc/NEWS

@@ -27,6 +27,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #19422: Explicitly disallow non-SOCK_STREAM sockets in the ssl
+  module, rather than silently let them emit clear text data.
+
 - Issue #20027: Fixed locale aliases for devanagari locales.
 
 - Issue #20067: Tkinter variables now work when wantobjects is false.