[Pki-devel] SSL handshake problem

[John Magne]

----- Original Message -----
From: "Nathan Kinder" <nkinder at redhat.com>
To: "Endi Sukma Dewata" <edewata at redhat.com>
Cc: "Bob Relyea" <rrelyea at redhat.com>, "pki-devel" <pki-devel at redhat.com>
Sent: Friday, August 17, 2012 2:07:36 PM
Subject: Re: [Pki-devel] SSL handshake problem



Adding Elio to the thread in case he has any thoughts on this... 

On 08/16/2012 11:49 AM, Endi Sukma Dewata wrote: 


Hi, 

I'm having a problem running a CLI operation on Dogtag 10 which seems to be caused by SSL handshake issue. Here are the steps to reproduce: 

1. Get the latest Dogtag 10 source code. 
2. Apply the attached pki-certrequest.patch. 
3. Get the pki-dev tools (see http://pki.fedoraproject.org/wiki/Testing ). 
4. Execute these commands in pki-dev/scripts to build and install CA: 

% ./theme-build.sh 
% ./theme-install.sh 
% ./core-build.sh 
% ./core-install.sh 
% ./ds-create.sh 
% ./ca-create.sh 

5. Then execute these test commands in pki-dev/scripts: 

% ./cert-request-submit.sh cert-request.xml (note the Request ID) 
% ./cert-request-review.sh <Request ID> review.xml 
% ./cert-request-approve.sh review.xml 

Both review and approve operations are done via SSL and they require client certificate authentication. However, the review works, but the approve operation fails with HTTP code 401 (Unauthorized). This is because the review is a GET operation which doesn't send any data, but the approve is a POST operation which sends a relatively large data. 

These commands use Apache HTTP Client library which has a parameter called MIN_CHUNK_LIMIT (see http://hc.apache.org/httpcomponents-core-ga/httpcore/apidocs/org/apache/http/params/CoreConnectionPNames.html ). The parameter is set to 512 bytes by default, so any request longer than that (such as the approve request) may be sent in multiple chunks. 

It seems that the current Tomcat JSS doesn't properly handle a request sent in multiple chunks. Currently the JSSSocketFactory.handshake() is not doing the handshake. The initial handshake is actually done when the server starts reading the data stream, without asking for the client certificate. Then when the server needs to get the client certificate it will do an SSL renegotiation in JSSSupport.getPeerCertificateChain(). For some reason the renegotiation fails if the request is sent in multiple chunks. 

One possible solution is to fix either Tomcat JSS, JSS, or NSS to handle multiple request chunks properly. We'll need an expert in this area to investigate and fix it. 

Another solution is to raise the MIN_CHUNK_LIMIT on the client, but there's a hard limit of 8 KB and there might be 3rd party clients which we can't control. 

Another possibility is we might be able to remove the requirement for renegotiation (still to be confirmed). Originally the renegotiation is needed to access some pages in Dogtag Web UI so it will prompt for client certificate. In Dogtag 10 we're doing some reorganization so renegotiation might not be needed anymore. In general unprotected UI pages would be accessed via unsecured port, but when the user tries to access a protected page he will be redirected to a secured port. Here the client certificate will be asked during the initial negotiation. Since there is no unauthenticated SSL connection, there is no need for renegotiation. 

Assuming we don't need renegotiation anymore, I attached a patch for Tomcat JSS (tomcatjss-handshake.patch) to do the initial negotiation in JSSSocketFactory.handshake() that will also ask for the client certificate. With this patch the approve operation will work properly. Is this the right solution? Are there other solutions? 

Thanks. 

Endi:

If we do the tomcatjss-handshake thing, does this still leave us with the Apache proxy ssl client cert issue? Or was that a consequence of renegotiation? I don't remember. Perhaps alee knows off the top of his head.



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