On Sun, Oct 13, 2019 at 10:31:31PM +0800, Drew Parsons wrote:
> 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)
For sure I'm missing something, but why not just set TLS version?
I tried the following on both Python2 and Python3:
>>> import ssl
>>> from urllib3.poolmanager import PoolManager
>>> http = PoolManager(ssl_version=ssl.PROTOCOL_TLSv1)
>>> r = http.request('GET', 'https://pub.orcid.org')
>>> r.status
200
> 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.
Not an expert here, but I think fallback is not done on purpose due downgrade
attacks: https://en.wikipedia.org/wiki/Downgrade_attack
> 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.
Fixed adding python{,3}-idna on B-D. I had to add python3-idna
because the same tests were failing also on Python3 when I tested
them buinding on DoM.
Kind regards,
--
Daniele Tricoli 'eriol'
https://mornie.org
Attachment:
signature.asc
Description: PGP signature