[issue31453] ssl.PROTOCOL_TLS only select TLSv1.2

[Adrian Vollmer]

New submission from Adrian Vollmer:

According to the documentation (https://docs.python.org/2/library/ssl.html#ssl.PROTOCOL_TLS), using ssl_version = ssl.PROTOCOL_TLS in a server socket should offer all TLS/SSL versions. However, it only offers TLSv1_2.

I attached a proof of concept.


$ python3 poc.py
3.5.4 (default, Aug 12 2017, 14:08:14)
[GCC 7.1.0]
OpenSSL 1.1.0f  25 May 2017
[SSL: UNSUPPORTED_PROTOCOL] unsupported protocol (_ssl.c:719)
[SSL: UNSUPPORTED_PROTOCOL] unsupported protocol (_ssl.c:719)
b'test\n'

$ python2 poc.py
2.7.13 (default, Jan 19 2017, 14:48:08)
[GCC 6.3.0 20170118]
OpenSSL 1.1.0f  25 May 2017
[SSL: UNSUPPORTED_PROTOCOL] unsupported protocol (_ssl.c:661)
[SSL: UNSUPPORTED_PROTOCOL] unsupported protocol (_ssl.c:661)
test


To connect with s_client:

 $ for i in {tls1,tls1_1,tls1_2} ; do echo test | openssl s_client -connect localhost:3333 -CAfile server.pem -quiet -$i ; done
140164347663616:error:1409442E:SSL routines:ssl3_read_bytes:tlsv1 alert protocol version:../ssl/record/rec_layer_s3.c:1399:SSL alert number 70
139926441944320:error:1409442E:SSL routines:ssl3_read_bytes:tlsv1 alert protocol version:../ssl/record/rec_layer_s3.c:1399:SSL alert number 70
depth=0 C = AU, ST = Some-State, O = Internet Widgits Pty Ltd
verify return:1
read:errno=0

----------
assignee: christian.heimes
components: SSL
files: poc.py
messages: 302081
nosy: adrianv, christian.heimes
priority: normal
severity: normal
status: open
title: ssl.PROTOCOL_TLS only select TLSv1.2
type: behavior
versions: Python 2.7, Python 3.5
Added file: https://bugs.python.org/file47139/poc.py

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<https://bugs.python.org/issue31453>
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