Public bug reported:
OpenSSL's SSL_do_handshake() method fails with
TLSV1_ALERT_INTERNAL_ERROR when client side has TLS 1.0 to 1.2 enabled
but server side has only TLS 1.0 and 1.1 enabled. The issue breaks
Python's test suite for test_ssl. It looks like the problem is caused by
an Ubuntu downstream patch. Vanilla OpenSSL, Debian, and Fedora are not
affected.
A simple reproducer is:
import ssl
import socket
from test.test_ssl import testing_context, ThreadedEchoServer, HOST
client_context, server_context, hostname = testing_context()
# client 1.0 to 1.2, server 1.0 to 1.1
client_context.minimum_version = ssl.TLSVersion.TLSv1
client_context.maximum_version = ssl.TLSVersion.TLSv1_2
server_context.minimum_version = ssl.TLSVersion.TLSv1
server_context.maximum_version = ssl.TLSVersion.TLSv1_1
with ThreadedEchoServer(context=server_context) as server:
with client_context.wrap_socket(socket.socket(),
server_hostname=hostname) as s:
s.connect((HOST, server.port))
assert s.version() == 'TLSv1.1'
On Ubuntu 20.04 the code fails with:
Traceback (most recent call last):
File "/internalerror.py", line 15, in <module>
s.connect((HOST, server.port))
File "/usr/lib/python3.8/ssl.py", line 1342, in connect
self._real_connect(addr, False)
File "/usr/lib/python3.8/ssl.py", line 1333, in _real_connect
self.do_handshake()
File "/usr/lib/python3.8/ssl.py", line 1309, in do_handshake
self._sslobj.do_handshake()
ssl.SSLError: [SSL: TLSV1_ALERT_INTERNAL_ERROR] tlsv1 alert internal error
(_ssl.c:1123)
On Debian testing and Fedora 33 the same test passes with out:
server: new connection from ('127.0.0.1', 52346)
server: connection cipher is now ('ECDHE-RSA-AES256-SHA', 'TLSv1.0', 256)
server: selected protocol is now None
You can find Dockerfiles with reproducers at https://github.com/tiran
/distro-truststore/tree/main/tests/ubuntu-1899878
Also see:
* https://bugs.launchpad.net/ubuntu/+source/openssl/+bug/1899878
* https://bugs.python.org/issue43382
* https://bugs.python.org/issue41561
** Affects: openssl (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1917625
Title:
OpenSSL TLS 1.1 handshake fails internal error
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