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

[Christian Heimes]

> s->cert->sec_cb() and then call it with SSL_SECOP_VERSION operation
with nbits set to TLS1.1 version? then it will return and tell us if it
is acceptable or not, by the security level.

Nice!
Could you hook up the check to SSL_CTX_set_min_proto_version() and return an error code when level and security policy don't match? It's a modern setter, so it can return 0 on error.

    int SSL_CTX_set_min_proto_version(SSL_CTX *ctx, int version);

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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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