[Koha] Plack plus shibboleth

Tue Sep 18 03:48:38 NZST 2018

https://metacpan.org/pod/Mojolicious::Plugin::SAML is another option, but
also relies on us switching away from Apache + Plack entirely and rather
letting hypnotoad act as the server itself and doing away with the native
service provider package entirely too.. but those are real long game goals
;)

*Martin Renvoize*

Development Team Manager

*T:* +44 (0) 1483 378728

*F:* +44 (0) 800 756 6384

*E:* martin.renvoize at ptfs-europe.com

www.ptfs-europe.com

<https://www.ptfs-europe.com>

Registered in the United Kingdom No. 06416372   VAT Reg No. 925 7211 30

The information contained in this email message may be privileged,
confidential and protected from disclosure. If you are not the intended
recipient, any dissemination, distribution or copying is strictly
prohibited. If you think that you have received this email message in
error, please email the sender at info at ptfs-europe.com

On Mon, 17 Sep 2018 at 16:36, Renvoize, Martin <
martin.renvoize at ptfs-europe.com> wrote:

> Sorry I've not got to this earlier,
>
> I'm languishing on that bug due to lack of funding/interest.
>
> You are entirely correct that there is no way to use environment variables
> when using apache merely as a proxy to plack, and that any middlewares etc
> just obfuscate this further moving it up the chain rather than actually
> resolving the problem.
>
> Tomas's suggestion of running just the authentication piece under CGI mode
> may work, although as this is called inside get_template_and_user on every
> request I'm not sure how it could happen short of basically turning off
> plack on everything.
>
> The final direction I was going to take was to add some sort of shared
> signature to the headers which I believe is recommended by the shibboleth
> folks themselves. This signature would need to be verified within Koha
> before accepting that the header has come from the Shibboleth service
> provider package and not through the client.
>
>
> Registered in the United Kingdom No. 06416372   VAT Reg No. 925 7211 30
>
> The information contained in this email message may be privileged,
> confidential and protected from disclosure. If you are not the intended
> recipient, any dissemination, distribution or copying is strictly
> prohibited. If you think that you have received this email message in
> error, please email the sender at info at ptfs-europe.com
>
>
>
> On Tue, 28 Aug 2018 at 17:23, Tomas Cohen Arazi <tomascohen at gmail.com>
> wrote:
>
>> I'm not familiar with the protocol workflow, but can't we just run some
>> bits in CGI mode to avoid this? (I imagine this is about the callback PL).
>> We already do this for other stuffs.
>>
>> El mar., 28 de ago. de 2018 07:39, Dave Sherohman <dave at sherohman.org>
>> escribió:
>>
>> > Plack::Auth::SSO::Shibboleth appears to fall into the "just pushes the
>> > issue back a level... without actually solving the core issue" from my
>> > original post.  Quoting the P::A::S::S docs,
>> >
>> > ---
>> > The real authenticating module lives inside the Apache web server, and
>> > is called "mod_shib".
>> > <snip>
>> > There are two ways to transfer the attributes from mod_shib to the
>> > application:
>> >
>> > * the application lives inside Apache (CGI, FCGI). The attributes are
>> >   sent as environment variables. This is the default situation, and the
>> >   most secure.
>> >
>> > * the application is a separate server, and Apache merely a proxy
>> >   server. The attributes are sent as headers. This is less secure.
>> >
>> > This module merely convert these attributes.
>> > ---
>> >
>> > Also, in the example "setup behind proxy" config, you can see that the
>> > apache configuration includes "ShibUseHeaders On".
>> >
>> > So it would appear that the module might be useful for receiving the
>> > http headers from mod_shib and converting them to environment variables,
>> > thus allowing koha to use them without needing to modify the koha code,
>> > but it does not appear to eliminate the need to use http headers in the
>> > first place.
>> >
>> > Of course, if anyone has actually used P::A::S::S and knows otherwise,
>> > I'm happy to be corrected on that point.
>> >
>> > On Tue, Aug 28, 2018 at 12:16:05PM +0200, Matthias Meusburger wrote:
>> > > Hi,
>> > >
>> > > Using something like Plack::Auth::SSO::Shibboleth might provide a
>> > solution
>> > > to this problem.
>> > >
>> > > https://metacpan.org/pod/Plack::Auth::SSO::Shibboleth
>> > >
>> > > Le 27/08/2018 à 20:12, Katrin Fischer a écrit :
>> > > >Hi Dave,
>> > > >
>> > > >I am not aware of a way to run Shibboleth with Plack in a safe way at
>> > the
>> > > >moment, but would also be very interested in seeing this resolved.
>> It's
>> > a
>> > > >rather big issue for academic libraries here.
>> > > >
>> > > >Katrin
>> > > >
>> > > >On 27.08.2018 10:41, Dave Sherohman wrote:
>> > > >>Hey, all!
>> > > >>
>> > > >>tl;dr: When running koha under plack and using shibboleth
>> > > >>authentication, what is the currently-recommended way to communicate
>> > > >>auth details from mod_shib to koha?
>> > > >>
>> > > >>
>> > > >>Long version:
>> > > >>
>> > > >>I'm in the process of converting our Koha installation from running
>> > > >>under vanilla CGI to using plack/starman.  This was simple enough
>> from
>> > > >>the perspsctive of straight-up library functionality, but we're
>> using
>> > > >>shibboleth to authenticate against the campus IDP, and that has
>> raised
>> > a
>> > > >>few issues.
>> > > >>
>> > > >>We've already found
>> > > >>https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=17776 in
>> the
>> > > >>bug tracker and I have successfully adapted the patch tou our
>> > customized
>> > > >>C4::Auth/C4::Auth_with_shibboleth and logged in via shibboleth, but
>> (as
>> > > >>noted in the bug tracker discussion) this uses HTTP headers to
>> > > >>communicate the authentication details to the back-end application.
>> > > >>
>> > > >>In order to avoid possible vulnerabilities resulting from the use of
>> > > >>HTTP headers, I went to the shibboleth documentation at
>> > > >>
>> >
>> https://wiki.shibboleth.net/confluence/display/SHIB2/NativeSPSpoofChecking
>> > > >>
>> > > >>[1] and, in the section for Apache, found the assertion that:
>> > > >>
>> > > >>"Under no circumstances should you rely on the request header option
>> > > >>other than as a temporary measure while adjusting applications to
>> use
>> > > >>the environment option. There are no known scenarios in which
>> > > >>environment variables can't be used"
>> > > >>
>> > > >>Is there a way to use environment variables in a plack+shibboleth
>> > > >>installation?  The docs assert that it should be possible (as there
>> are
>> > > >>"no known scenarios" where it isn't), but that would imply that one
>> > > >>process (apache) is able to modify the environment of another,
>> already-
>> > > >>running, independent non-child process (starman) running under a
>> > > >>different uid/gid, which should not generally be possible - and,
>> even
>> > if
>> > > >>it is possible, it would require apache to run as root, which would
>> > > >>create major security risks of its own.
>> > > >>
>> > > >>The bug tracker discussion includes a brief mention of possibly
>> using a
>> > > >>plack middleware to change the worker process envoronment, but that
>> > > >>seems like it would just push the issue back a level from "how do I
>> > talk
>> > > >>to starman without using http headers" to "how do I talk to the
>> > > >>middleware without using http headers" without actually solving the
>> > core
>> > > >>issue.
>> > > >>
>> > > >>Is it actually possible to use environment variables in this
>> scenario?
>> > > >>If not, what's the best practice to secure it against http header
>> > > >>spoofing?
>> > > >>
>> > > >>
>> > > >>[1] The SHIB2 documentation states that it's no longer supported,
>> but
>> > > >>we're using an sp2 shibd and, in any case, the same text appears
>> > > >>verbatim on the equivalent SP3 page.
>> > > >>
>> > > >
>> > > >_______________________________________________
>> > > >Koha mailing list  http://koha-community.org
>> > > >Koha at lists.katipo.co.nz
>> > > >https://lists.katipo.co.nz/mailman/listinfo/koha
>> > > _______________________________________________
>> > > Koha mailing list  http://koha-community.org
>> > > Koha at lists.katipo.co.nz
>> > > https://lists.katipo.co.nz/mailman/listinfo/koha
>> >
>> >
>> > --
>> > Dave Sherohman
>> > _______________________________________________
>> > Koha mailing list  http://koha-community.org
>> > Koha at lists.katipo.co.nz
>> > https://lists.katipo.co.nz/mailman/listinfo/koha
>> >
>> --
>> Tomás Cohen Arazi
>> Theke Solutions (https://theke.io <http://theke.io/>)
>> ✆ +54 9351 3513384
>> GPG: B2F3C15F
>> _______________________________________________
>> Koha mailing list  http://koha-community.org
>> Koha at lists.katipo.co.nz
>> https://lists.katipo.co.nz/mailman/listinfo/koha
>>
>