bpo-38686: fix HTTP Digest handling in request.py by PypeBros · Pull Request #17045 · python/cpython

PypeBros · 2019-11-04T15:28:34Z

There is a bug triggered when server replies to a request with WWW-Authenticate: Digest where qop="auth,auth-int" rather than mere qop="auth". Having both auth and auth-int is legitimate according to the qop-options rule in §3.2.1 of https://www.ietf.org/rfc/rfc2617.txt:

 qop-options       = "qop" "=" <"> 1#qop-value <">
 qop-value         = "auth" | "auth-int" | token
qop-options: [...] If present, it is a quoted string of one or more tokens indicating the "quality of protection" values supported by the server. The value "auth" indicates authentication; the value "auth-int" indicates authentication with integrity protection

This is description confirmed by the definition of the [n]#[m]rule extended-BNF pattern defined in §2.1 of https://www.ietf.org/rfc/rfc2616.txt as 'a comma-separated list of rule with at least n and at most m items'.

When this reply is parsed by get_authorization, request.py only tests for identity with 'auth', failing to recognize it as one of the supported modes the server announced, and claims that "qop 'auth,auth-int' is not supported".

https://bugs.python.org/issue38686

There is a bug triggered when server replies to a request with `WWW-Authenticate: Digest` where `qop="auth,auth-int"` rather than mere `qop="auth"`. Having both `auth` and `auth-int` is legitimate according to the `qop-options` rule in §3.2.1 of [[https://www.ietf.org/rfc/rfc2617.txt|RFC 2617]]: > qop-options = "qop" "=" <"> 1#qop-value <"> > qop-value = "auth" | "auth-int" | token > **qop-options**: [...] If present, it is a quoted string **of one or more** tokens indicating the "quality of protection" values supported by the server. The value `"auth"` indicates authentication; the value `"auth-int"` indicates authentication with integrity protection This is description confirmed by the definition of the [//n//]`#`[//m//]//rule// extended-BNF pattern defined in §2.1 of [[https://www.ietf.org/rfc/rfc2616.txt|RFC 2616]] as 'a comma-separated list of //rule// with at least //n// and at most //m// items'. When this reply is parsed by `get_authorization`, request.py only tests for identity with `'auth'`, failing to recognize it as one of the supported modes the server announced, and claims that `"qop 'auth,auth-int' is not supported"`.

the-knights-who-say-ni · 2019-11-04T15:28:38Z

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brandtbucher · 2019-11-04T17:31:45Z

Thanks for your time @PypeBros, and welcome to CPython! 😎

I assume that you've seen the bot's message about the CLA? Also, if the issue will properly link if you add "bpo-" to the start of this PR's title!

brandtbucher

I'm not a urllib expert, but the code itself looks good.

This PR should also have a NEWS entry. Just something simple, like:

Added support for multiple ``qop`` values in :class:`urllib.request.AbstractDigestAuthHandler`.

I think this also needs a test or two, in Lib/test/test_urllib2.py.

PypeBros · 2019-11-06T16:11:57Z

@brandtbucher : thanks for the welcome and for the help.
I had a look at test_urllib2, but I'm unsure I could write appropriate test cases myself as I don't even see code testing how the DigestAuthHandler would process a valid 'Digest' reply, only code that check it wouldn't prevent BasicAuthHandler from grabbing basic authentication requests.

brandtbucher

Ah, I see there's not many tests for this class at all. I'll leave that for the core reviewer to decide!

brandtbucher · 2019-11-06T19:26:43Z

CC @orsenthil

PypeBros · 2019-11-13T09:36:31Z

Any follow up ? Afaik, in its current state, it makes python clients unable to inter-operate securely with gSOAP clients.

orsenthil

Hi @PypeBros - Thank you for your contribution.

Please see my review comments on this ticket and let me know what your thoughts are.

PypeBros · 2019-11-18T08:05:52Z

@orsenthil, does the replies above address your concern with the proposed change ?

PypeBros · 2019-11-22T17:14:41Z

here you are. I haven't repeated the "XXX: implement auth-int", as this is already on line 1154

orsenthil

Thank you!

PypeBros · 2019-11-22T17:28:10Z

anybody understands why https://travis-ci.org/python/cpython/jobs/615649384?utm_medium=notification&utm_source=github_status failed with "Please fix the 1 file(s) with whitespace issues" ?

Co-Authored-By: Brandt Bucher <brandtbucher@gmail.com>

bedevere-bot · 2019-11-22T23:19:11Z

@orsenthil: Please replace # with GH- in the commit message next time. Thanks!

miss-islington · 2019-11-22T23:19:11Z

Thanks @PypeBros for the PR, and @orsenthil for merging it 🌮🎉.. I'm working now to backport this PR to: 3.7, 3.8.
🐍🍒⛏🤖

* fix HTTP Digest handling in request.py There is a bug triggered when server replies to a request with `WWW-Authenticate: Digest` where `qop="auth,auth-int"` rather than mere `qop="auth"`. Having both `auth` and `auth-int` is legitimate according to the `qop-options` rule in §3.2.1 of [[https://www.ietf.org/rfc/rfc2617.txt|RFC 2617]]: > qop-options = "qop" "=" <"> 1GH-qop-value <"> > qop-value = "auth" | "auth-int" | token > **qop-options**: [...] If present, it is a quoted string **of one or more** tokens indicating the "quality of protection" values supported by the server. The value `"auth"` indicates authentication; the value `"auth-int"` indicates authentication with integrity protection This is description confirmed by the definition of the [//n//]`GH-`[//m//]//rule// extended-BNF pattern defined in §2.1 of [[https://www.ietf.org/rfc/rfc2616.txt|RFC 2616]] as 'a comma-separated list of //rule// with at least //n// and at most //m// items'. When this reply is parsed by `get_authorization`, request.py only tests for identity with `'auth'`, failing to recognize it as one of the supported modes the server announced, and claims that `"qop 'auth,auth-int' is not supported"`. * 📜🤖 Added by blurb_it. * bpo-38686 review fix: remember why. * fix trailing space in Lib/urllib/request.py Co-Authored-By: Brandt Bucher <brandtbucher@gmail.com> (cherry picked from commit 14a89c4) Co-authored-by: PypeBros <PypeBros@users.noreply.github.com>

bedevere-bot · 2019-11-22T23:19:21Z

GH-17357 is a backport of this pull request to the 3.8 branch.

bedevere-bot · 2019-11-22T23:19:27Z

GH-17358 is a backport of this pull request to the 3.7 branch.

* fix HTTP Digest handling in request.py There is a bug triggered when server replies to a request with `WWW-Authenticate: Digest` where `qop="auth,auth-int"` rather than mere `qop="auth"`. Having both `auth` and `auth-int` is legitimate according to the `qop-options` rule in §3.2.1 of [[https://www.ietf.org/rfc/rfc2617.txt|RFC 2617]]: > qop-options = "qop" "=" <"> 1GH-qop-value <"> > qop-value = "auth" | "auth-int" | token > **qop-options**: [...] If present, it is a quoted string **of one or more** tokens indicating the "quality of protection" values supported by the server. The value `"auth"` indicates authentication; the value `"auth-int"` indicates authentication with integrity protection This is description confirmed by the definition of the [//n//]`GH-`[//m//]//rule// extended-BNF pattern defined in §2.1 of [[https://www.ietf.org/rfc/rfc2616.txt|RFC 2616]] as 'a comma-separated list of //rule// with at least //n// and at most //m// items'. When this reply is parsed by `get_authorization`, request.py only tests for identity with `'auth'`, failing to recognize it as one of the supported modes the server announced, and claims that `"qop 'auth,auth-int' is not supported"`. * 📜🤖 Added by blurb_it. * bpo-38686 review fix: remember why. * fix trailing space in Lib/urllib/request.py Co-Authored-By: Brandt Bucher <brandtbucher@gmail.com> (cherry picked from commit 14a89c4) Co-authored-by: PypeBros <PypeBros@users.noreply.github.com>

* fix HTTP Digest handling in request.py There is a bug triggered when server replies to a request with `WWW-Authenticate: Digest` where `qop="auth,auth-int"` rather than mere `qop="auth"`. Having both `auth` and `auth-int` is legitimate according to the `qop-options` rule in §3.2.1 of [[https://www.ietf.org/rfc/rfc2617.txt|RFC 2617]]: > qop-options = "qop" "=" <"> 1#qop-value <"> > qop-value = "auth" | "auth-int" | token > **qop-options**: [...] If present, it is a quoted string **of one or more** tokens indicating the "quality of protection" values supported by the server. The value `"auth"` indicates authentication; the value `"auth-int"` indicates authentication with integrity protection This is description confirmed by the definition of the [//n//]`#`[//m//]//rule// extended-BNF pattern defined in §2.1 of [[https://www.ietf.org/rfc/rfc2616.txt|RFC 2616]] as 'a comma-separated list of //rule// with at least //n// and at most //m// items'. When this reply is parsed by `get_authorization`, request.py only tests for identity with `'auth'`, failing to recognize it as one of the supported modes the server announced, and claims that `"qop 'auth,auth-int' is not supported"`. * 📜🤖 Added by blurb_it. * bpo-38686 review fix: remember why. * fix trailing space in Lib/urllib/request.py Co-Authored-By: Brandt Bucher <brandtbucher@gmail.com>

the-knights-who-say-ni added the CLA not signed label Nov 4, 2019

bedevere-bot added the awaiting review label Nov 4, 2019

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bedevere-bot added awaiting core review and removed awaiting review labels Nov 4, 2019

brandtbucher added the type-bug An unexpected behavior, bug, or error label Nov 4, 2019

the-knights-who-say-ni added CLA signed and removed CLA not signed labels Nov 5, 2019

PypeBros changed the title ~~38686: fix HTTP Digest handling in request.py~~ bpo-38686: fix HTTP Digest handling in request.py Nov 5, 2019

📜🤖 Added by blurb_it.

5ade571

brandtbucher approved these changes Nov 6, 2019

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orsenthil reviewed Nov 13, 2019

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Comment thread Lib/urllib/request.py

bpo-38686 review fix: remember why.

432c7b9

orsenthil approved these changes Nov 22, 2019

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bedevere-bot added awaiting merge and removed awaiting core review labels Nov 22, 2019

brandtbucher requested changes Nov 22, 2019

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Comment thread Lib/urllib/request.py Outdated

fix trailing space in Lib/urllib/request.py

95c6eef

Co-Authored-By: Brandt Bucher <brandtbucher@gmail.com>

brandtbucher approved these changes Nov 22, 2019

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orsenthil approved these changes Nov 22, 2019

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orsenthil added the needs backport to 3.7 label Nov 22, 2019

orsenthil added the needs backport to 3.8 label Nov 22, 2019

orsenthil merged commit 14a89c4 into python:master Nov 22, 2019

bedevere-bot removed the awaiting merge label Nov 22, 2019

bedevere-bot removed the needs backport to 3.8 label Nov 22, 2019

bedevere-bot removed the needs backport to 3.7 label Nov 22, 2019

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