[Bug 1917625] Re: OpenSSL TLS 1.1 handshake fails internal error

[Dimitri John Ledkov]

Please note that:

OpenSSL upstream security level 3 only allows TLS v1.1 and above
OpenSSL upstream security level 4 only allows TLS v1.2 and above, DTLS v1.2 and above

On Ubuntu, these restrictions are brought in earlier at security level
2.

Thus, if one builds upstream OpenSSL with security level set to 4 all of
the above testsuite should be failing as well.

I feel there is lack of API documentation about this in OpenSSL.

Also, Python tests are incomplete and are not testing for, or setting
appropriate security levels for the protocols they are attempting to
use. Thus are not using the OpenSSL api correctly and making assumptions
about the openssl library that are out of date with current standards
and requirements.

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https://bugs.launchpad.net/bugs/1917625

Title:
  OpenSSL TLS 1.1 handshake fails internal error

Status in openssl package in Ubuntu:
  Confirmed
Status in openssl source package in Hirsute:
  Confirmed

Bug description:
  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

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