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Re: python-urllib3 1.25.6 uploaded to experimental (closes CVE-2019-11236) but fails build tests

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Daniele wrote:
> I hope to have the time to investigate also this: 
> urllib3/contrib/pyopenssl.py
> contains code to have SSL with SNI_-support for Python 2 and it depends 
> on
> pyOpenSSL, cryptography and idna. Maybe looking at them can give us 
> more clues.

> Also, could you see if using Python3 the connection to 
> https://pub.orcid.org work?

It conditionally works.  Using curl, I found that TLSv1_0 or TLSv1_1 
will support a successful connection, but only if the maximum 
SSL_VERSION is constrained to TLSv1_0 or TLSv1_1 (e.g. curl -v --tlsv1.1 
--tls-max 1.1  https://pub.orcid.org). Without the max, the connection 
fails:
$ curl --tlsv1.1  https://pub.orcid.org
curl: (35) error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert 
handshake failure

The urllib3 failure was similar, but I do not know how to set tls-max 
with urllib3. I could only find the option with curl.  I could set up a 
custom HTTPAdapter as suggested at 
https://requests.readthedocs.io/en/master/user/advanced/#example-specific-ssl-version 
to set ssl_version=ssl.PROTOCOL_TLSv1_1 but the ssl module doesn't have 
the SSLVERSION_MAX_TLSv1_1 value that curl has. I could solve it with 
pycurl using c.setopt(pycurl.SSLVERSION, pycurl.SSLVERSION_TLSv1_1 | 
pycurl.SSLVERSION_MAX_TLSv1_1)

Evidently the orcid server only supports TLSv1.0 and TLSv1.1 and no 
higher (why haven't they activated TLSv1.3 yet?!), while curl and 
urllib3 without tls-max first test TLSv1.3 and then quit without 
cascading downwards once they receive the TLSv1.3 handshake failure.  
Which is rather odd behaviour when I think about it.  The whole point of 
supporting multiple protocol versions is to try the next available 
version if the first one doesn't work.



>> Th package build was successful on my system but gives build-time 
>> errors in
>> chroot (on buildd).  I'm not sure why that's failing.
> I will look at them during this weekend, I already had a look at build 
> log from
> the phone, but it's better to look from a PC.

I had a closer look.  The failing tests were in python2 only, coming 
from the non-ascii (Gërman http://Königsgäßchen.de/straße and Japanese 
http://ヒ:キ@ヒ.abc.ニ/ヒ?キ#ワ) unicode url tests. So from one perspective we 
don't need to worry so much about them, we could just disable them (e.g. 
prepend @onlyPy3 to test_parse_url and test_url_vulnerabilities in 
test_util.py). We'll be dropping python2 any way in the near future.

On the other hand, given the nature of the vulnerabilities and the 
possible uses of urllib3, it's probably best not to leave python2 
untested, especially since they are known to pass on python2 anyway in 
the right conditions.  Probably there is some package that should be 
added to Build-Depends to enable python2 tests to pass, though I have no 
idea which that package might be.

Drew

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Re: python-urllib3 1.25.6 uploaded to experimental (closes  CVE-2019-11236) but fails build tests Drew Parsons <dparsons@debian.org> - 2019-10-13 16:40 +0200
  Re: python-urllib3 1.25.6 uploaded to experimental (closes  CVE-2019-11236) but fails build tests Daniele Tricoli <eriol@debian.org> - 2019-10-27 16:30 +0100
    Re: python-urllib3 1.25.6 uploaded to experimental (closes  CVE-2019-11236) but fails build tests Drew Parsons <dparsons@debian.org> - 2019-10-27 17:30 +0100
      Re: python-urllib3 1.25.6 uploaded to experimental (closes  CVE-2019-11236) but fails build tests Michael Kesper <mkesper@schokokeks.org> - 2019-10-29 13:30 +0100
        Re: python-urllib3 1.25.6 uploaded to experimental (closes  CVE-2019-11236) but fails build tests Ondrej Novy <novy@ondrej.org> - 2019-10-29 14:20 +0100
        Re: python-urllib3 1.25.6 uploaded to experimental (closes  CVE-2019-11236) but fails build tests Jeremy Stanley <fungi@yuggoth.org> - 2019-10-29 14:40 +0100
          Re: python-urllib3 1.25.6 uploaded to experimental (closes  CVE-2019-11236) but fails build tests Michael Kesper <mkesper@schokokeks.org> - 2019-10-29 15:40 +0100

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