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

[Dimitri John Ledkov]

I need to verify a few things, but I believe it is to do with
chiphersuites, seclevel callback, and protocol versions.

When setting chiphersuite string ; or changing security level; or
changing the security level callback; or setting min/mas protocol
versions. All of those things are not checked against each other to
ensure that as whole they are compatible with each.

Then at connection establishment time things are verified and security
callback is called and things go "you request max version y, but
security hook rejects things at y, no connection for you".

This does brings the existential/API question similar to the previous
bug report. It is not known over the API that security level is 2 and
that it rejects protocol versions.

I wonder, if setting min_version / max_version, that would be rejected
by the current security level, if security level should be adjusted
appropriately automatically. I.e. when trying to set min protocol
version to TLS1.1 and the security level is at 2, if security level
should be updated to 1 automatically. Or not.

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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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