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Re: [EP-tech] Redirect loop after shibboleth authentication

Hi Lee,

For 3.4.5 there was a change from 3.4.4 which set SameSite to Strict rather than None, as there were concerns over security using the previous setting [1].  However, I interpreted that you said that both your current CentOS 7 and your upgraded RHEL 8 server were both running EPrints 3.4.5 so this would not have changed.  

Another change between 3.4.4 and 3.4.5 is that if you have "securehost" configured then only the "secure_eprints_session..." cookie will be set and not the "eprints_session cookie" [2].  This is why I was concerned that at some point in your loop you may have hit an HTTP rather than HTTPS page for /cgi/users/home and therefore there would be no session cookie to make /cgi/users/home pick up you were already authenticated, as there would be no "eprints_session cookie" is this would have been disabled because you have "securehost" configured and there would be no "secure_eprints_session" sent because the URL would were request was not secure (i.e. HTTPS) and your browser will not send the "secure_eprints_session" cookie in a request if the "secure" flag is set to "true",

My advice would be to check your /shibboleth/login script check to see what is set as the parameter (e.g. $url ) for $session->redirect( $url ).  If this uses HTTP rather than HTTPS that will be your problem.  Looking at the wiki page [3] the default value for URL is the "userhome" config variable but it should use the target parameter if that is set.  From your example it looks like this is an HTTPS URL, so maybe this is not the issue but I cannot think of anything else it could be based on the information you have so far provided.

Regards

David Newman

[1] https://github.com/eprints/eprints3.4/issues/311

[2] https://github.com/eprints/eprints3.4/issues/278

[3] https://wiki.eprints.org/w/Shibboleth#EPrints_.2Fshibboleth.2Flogin_script_with_user_account_creation

On 19/01/2024 12:07, Lee Paton wrote:
CAUTION: This e-mail originated outside the University of Southampton.
CAUTION: This e-mail originated outside the University of Southampton.

Hi Dave

 

Thanks for your quick reply

 

This is what I’m seeing getting the cookie info from Firefox from the request

 

./shibboleth/login?target=https%3A%2F%2Forca-dev2.cardiff.ac.uk%2Fcgi%2Fusers%2Fhome

 

{

        "Response Cookies": {

                "secure_eprints_session:orca-dev2.cardiff.ac.uk": {

                        "domain": "orca-dev2.cardiff.ac.uk",

                        "path": "/",

                        "samesite": "Strict",

                        "secure": true,

                        "value": "1d48249d81423fe7fcd6e37d8b00a748"

                }

        }

}

 

{

        "Request Cookies": {

                "_ga": "GA1.1.512524483.1705663780",

                "_ga_RRV66RFBKP": "GS1.1.1705663779.1.0.1705663784.0.0.0",

                "_shibsession_xxx": "_9e2b8035712cbd57a6b7dc816a7545e4"

        }

}

 

And when it redirects to ./cgi/users/home (where it loops)

 

{

        "Request Cookies": {

                "_ga": "GA1.1.512524483.1705663780",

                "_ga_RRV66RFBKP": "GS1.1.1705663779.1.0.1705663784.0.0.0",

                "_shibsession_xxx": "_9e2b8035712cbd57a6b7dc816a7545e4"

        }

}

 

When I refresh the cookies are

 

{

        "Request Cookies": {

                "_ga": "GA1.1.1118556027.1705664127",

                "_ga_RRV66RFBKP": "GS1.1.1705664127.1.0.1705664127.0.0.0",

                "_shibsession_xxx": "_27e34d6d248703d1d0cacdc14ad393f8",

                "secure_eprints_session:orca-dev.cardiff.ac.uk": "1a81565f2d54425ba0a6ed135d7feb3c"

        }       

}    

 

The difference between this and the working CentOS 7 server is that the secure_eprints_session value is set on the initial request to /cgi/users/home, I’ve also noticed that

 

"samesite": "Strict",

 

Isn’t set on the CentOS 7 server – As far as I’m aware I haven’t changed this at all so should be set to strict on both

 

Thanks again

 

Lee

 

From: David R Newman <drn@ecs.soton.ac.uk>
Date: Thursday, 18 January 2024 at 15:18
To: eprints-tech@ecs.soton.ac.uk <eprints-tech@ecs.soton.ac.uk>, Lee Paton <PatonL@cardiff.ac.uk>
Subject: Re: [EP-tech] Redirect loop after shibboleth authentication

External email to Cardiff University - Take care when replying/opening attachments or links.

Nid ebost mewnol o Brifysgol Caerdydd yw hwn - Cymerwch ofal wrth ateb/agor atodiadau neu ddolenni.

 

Hi Lee,

So there could be a few issues here.  It may be useful if you can show a couple of iterations of the redirect loop, as this may help identify some minor technicality like a switch between HTTP and HTTPS or a missing or present trailing slash.

/shibboleth/login should redirect you to /cgi/users/home if you current user session has appropriate environment variables set for an authenticated Shibboleth session, otherwise is will like redirect you to /account_required.html.  It seems like /shibboleth/login is redirecting to /cgi/users/home and then as it cannot find the secure_eprints_session... cookie it is redirecting back to /shibboleth/login,   Clearly this could be a race condition with the secure_eprint_session not being set and therefore sent a part of your request for /cgi/users/home. However, when you manually refresh the page your user session has received the required cookie and then sends it in this request.

From what you have said your version of EPrints has not changed (it was 3.4.5 prior to the migration) and all that has really changed is a newer operating system, with virtually everything else much the same.  My suspicion is that at some point there is an HTTP rather than HTTPS URL, which means the secure_eprints_session will not be available as it has "Secure" attribute set to "true".  When you do see secure_eprints_session cookie it would be useful if you could share the its attribute like my example below:

secure_eprints_session%3Aexample.eprints.org:"ef9def123af12384e9abcd1a49ea27abc"
Created:"Wed, 17 Jan 2024 14:45:37 GMT"
Domain:".example.eprints.org"
Expires / Max-Age:"Session"
HostOnly:false
HttpOnly:false
Last Accessed:"Thu, 18 Jan 2024 15:12:39 GMT"
Path:"/"
SameSite:"Strict"
Secure:true
Size:82

 

Regards

 

David Newman

 

On 18/01/2024 14:46, Lee Paton wrote:

CAUTION: This e-mail originated outside the University of Southampton.

CAUTION: This e-mail originated outside the University of Southampton.

Hi

 

I’m currently migrating our eprints (version 3.4.5) repository from CentOS 7 to RHEL 8, everything has gone smoothly  apart from the repository going into a redirect loop after the session has authenticated and you’re redirected back to a logged in session on the repo with:

 

https://orca-dev2.cardiff.ac.uk/shibboleth/login?target=https%3A%2F%2Forca-dev2.cardiff.ac.uk%2Fcgi%2Fusers%2Fhome

 

If you then hit return on the browsers address the users home page is displayed successfully

 

Looking at the http headers it appears that the secure_eprints_session value isn’t being set in a cookie (I’ve compared headers to the working CentOS 7 dev system) on that first redirect after shibboleth authentication has completed

 

The config is identical to the one that is currently running on our CentOS 7 environment, and the versions of Apache are also the same, there is a small difference in perl versions (5.16 and 5.26). The main difference is that I’m using our test idp to authenticate against using a hosts file change on my macbook instead of using out production idp.  Would this make a difference?

 

Any pointers or suggestions would be much appreciated – I’ve hit a brick wall with this

 

Thanks

 

Lee



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