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bpo-45129 Remove deprecated reuse_address (GH-28207)

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Due to significant security concerns, the reuse_address parameter of
asyncio.loop.create_datagram_endpoint, deprecated in Python 3.9, is
now removed. This is because of the behavior of the socket option
SO_REUSEADDR in UDP.

Co-authored-by: Łukasz Langa <lukasz@langa.pl>
This commit is contained in:
Hugo van Kemenade 2021-09-08 19:58:43 +03:00 • committed by GitHub
parent a561005761
commit 59ea704df7
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 33 additions and 70 deletions
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38
Doc/library/asyncio-eventloop.rst
View file

@ -493,24 +493,9 @@ Opening network connections
.. coroutinemethod:: loop.create_datagram_endpoint(protocol_factory, \
local_addr=None, remote_addr=None, *, \
family=0, proto=0, flags=0, \
reuse_address=None, reuse_port=None, \
reuse_port=None, \
allow_broadcast=None, sock=None)
.. note::
The parameter *reuse_address* is no longer supported, as using
:py:data:`~sockets.SO_REUSEADDR` poses a significant security concern for
UDP. Explicitly passing ``reuse_address=True`` will raise an exception.
When multiple processes with differing UIDs assign sockets to an
identical UDP socket address with ``SO_REUSEADDR``, incoming packets can
become randomly distributed among the sockets.
For supported platforms, *reuse_port* can be used as a replacement for
similar functionality. With *reuse_port*,
:py:data:`~sockets.SO_REUSEPORT` is used instead, which specifically
prevents processes with differing UIDs from assigning sockets to the same
socket address.
Create a datagram connection.
The socket family can be either :py:data:`~socket.AF_INET`,
@ -557,16 +542,31 @@ Opening network connections
:ref:`UDP echo server protocol <asyncio-udp-echo-server-protocol>` examples.
.. versionchanged:: 3.4.4
The *family*, *proto*, *flags*, *reuse_address*, *reuse_port,
The *family*, *proto*, *flags*, *reuse_address*, *reuse_port*,
*allow_broadcast*, and *sock* parameters were added.
.. versionchanged:: 3.8.1
The *reuse_address* parameter is no longer supported due to security
concerns.
The *reuse_address* parameter is no longer supported, as using
:py:data:`~sockets.SO_REUSEADDR` poses a significant security concern for
UDP. Explicitly passing ``reuse_address=True`` will raise an exception.
When multiple processes with differing UIDs assign sockets to an
identical UDP socket address with ``SO_REUSEADDR``, incoming packets can
become randomly distributed among the sockets.
For supported platforms, *reuse_port* can be used as a replacement for
similar functionality. With *reuse_port*,
:py:data:`~sockets.SO_REUSEPORT` is used instead, which specifically
prevents processes with differing UIDs from assigning sockets to the same
socket address.
.. versionchanged:: 3.8
Added support for Windows.
.. versionchanged:: 3.11
The *reuse_address* parameter, disabled since Python 3.9.0, 3.8.1,
3.7.6 and 3.6.10, has been entirely removed.
.. coroutinemethod:: loop.create_unix_connection(protocol_factory, \
path=None, *, ssl=None, sock=None, \
server_hostname=None, ssl_handshake_timeout=None)

6
Doc/whatsnew/3.11.rst
View file

@ -254,6 +254,12 @@ Removed
Use ``bdist_wheel`` (wheel packages) instead.
(Contributed by Hugo van Kemenade in :issue:`45124`.)
* Due to significant security concerns, the *reuse_address* parameter of
:meth:`asyncio.loop.create_datagram_endpoint`, disabled in Python 3.9, is
now entirely removed. This is because of the behavior of the socket option
``SO_REUSEADDR`` in UDP.
(Contributed by Hugo van Kemenade in :issue:`45129`.)
* Remove :meth:`__getitem__` methods of
:class:`xml.dom.pulldom.DOMEventStream`, :class:`wsgiref.util.FileWrapper`
and :class:`fileinput.FileInput`, deprecated since Python 3.9.

27
Lib/asyncio/base_events.py
View file

@ -66,10 +66,6 @@ _HAS_IPv6 = hasattr(socket, 'AF_INET6')
# Maximum timeout passed to select to avoid OS limitations
MAXIMUM_SELECT_TIMEOUT = 24 * 3600
# Used for deprecation and removal of `loop.create_datagram_endpoint()`'s
# *reuse_address* parameter
_unset = object()
def _format_handle(handle):
cb = handle._callback
@ -1235,7 +1231,7 @@ class BaseEventLoop(events.AbstractEventLoop):
async def create_datagram_endpoint(self, protocol_factory,
local_addr=None, remote_addr=None, *,
family=0, proto=0, flags=0,
reuse_address=_unset, reuse_port=None,
reuse_port=None,
allow_broadcast=None, sock=None):
"""Create datagram connection."""
if sock is not None:
@ -1248,7 +1244,7 @@ class BaseEventLoop(events.AbstractEventLoop):
# show the problematic kwargs in exception msg
opts = dict(local_addr=local_addr, remote_addr=remote_addr,
family=family, proto=proto, flags=flags,
reuse_address=reuse_address, reuse_port=reuse_port,
reuse_port=reuse_port,
allow_broadcast=allow_broadcast)
problems = ', '.join(f'{k}={v}' for k, v in opts.items() if v)
raise ValueError(
@ -1311,19 +1307,6 @@ class BaseEventLoop(events.AbstractEventLoop):
exceptions = []
# bpo-37228
if reuse_address is not _unset:
if reuse_address:
raise ValueError("Passing `reuse_address=True` is no "
"longer supported, as the usage of "
"SO_REUSEPORT in UDP poses a significant "
"security concern.")
else:
warnings.warn("The *reuse_address* parameter has been "
"deprecated as of 3.5.10 and is scheduled "
"for removal in 3.11.", DeprecationWarning,
stacklevel=2)
for ((family, proto),
(local_address, remote_address)) in addr_pairs_info:
sock = None
@ -1407,7 +1390,6 @@ class BaseEventLoop(events.AbstractEventLoop):
sock=None,
backlog=100,
ssl=None,
reuse_address=None,
reuse_port=None,
ssl_handshake_timeout=None,
start_serving=True):
@ -1438,8 +1420,6 @@ class BaseEventLoop(events.AbstractEventLoop):
raise ValueError(
'host/port and sock can not be specified at the same time')
if reuse_address is None:
reuse_address = os.name == 'posix' and sys.platform != 'cygwin'
sockets = []
if host == '':
hosts = [None]
@ -1469,9 +1449,6 @@ class BaseEventLoop(events.AbstractEventLoop):
af, socktype, proto, exc_info=True)
continue
sockets.append(sock)
if reuse_address:
sock.setsockopt(
socket.SOL_SOCKET, socket.SO_REUSEADDR, True)
if reuse_port:
_set_reuseport(sock)
# Disable IPv4/IPv6 dual stack support (enabled by

26
Lib/test/test_asyncio/test_base_events.py
View file

@ -1794,32 +1794,6 @@ class BaseEventLoopWithSelectorTests(test_utils.TestCase):
self.loop.run_until_complete(protocol.done)
self.assertEqual('CLOSED', protocol.state)
def test_create_datagram_endpoint_reuse_address_error(self):
# bpo-37228: Ensure that explicit passing of `reuse_address=True`
# raises an error, as it is not safe to use SO_REUSEADDR when using UDP
coro = self.loop.create_datagram_endpoint(
lambda: MyDatagramProto(create_future=True, loop=self.loop),
local_addr=('127.0.0.1', 0),
reuse_address=True)
with self.assertRaises(ValueError):
self.loop.run_until_complete(coro)
def test_create_datagram_endpoint_reuse_address_warning(self):
# bpo-37228: Deprecate *reuse_address* parameter
coro = self.loop.create_datagram_endpoint(
lambda: MyDatagramProto(create_future=True, loop=self.loop),
local_addr=('127.0.0.1', 0),
reuse_address=False)
with self.assertWarns(DeprecationWarning):
transport, protocol = self.loop.run_until_complete(coro)
transport.close()
self.loop.run_until_complete(protocol.done)
self.assertEqual('CLOSED', protocol.state)
@patch_socket
def test_create_datagram_endpoint_nosoreuseport(self, m_socket):
del m_socket.SO_REUSEPORT

6
Misc/NEWS.d/next/Library/2021-09-07-14-27-39.bpo-45129.vXH0gw.rst Normal file
View file

@ -0,0 +1,6 @@
Due to significant security concerns, the *reuse_address* parameter of
:meth:`asyncio.loop.create_datagram_endpoint`, disabled in Python 3.9, is
now entirely removed. This is because of the behavior of the socket option
``SO_REUSEADDR`` in UDP.
Patch by Hugo van Kemenade.