New SSL features for Nginx.

[Igor Sysoev]

On Wed, Jul 22, 2009 at 09:13:55PM +0200, Brice Figureau wrote:

> On 22/07/09 20:43, Igor Sysoev wrote:
> >On Wed, Jul 22, 2009 at 07:20:39PM +0200, Brice Figureau wrote:
> >
> >>On 22/07/09 14:16, Igor Sysoev wrote:
> >>>On Wed, Jul 22, 2009 at 12:21:23PM +0200, Brice Figureau wrote:
> >>>
> >>>>Hi Igor,
> >>>>
> >>>>On Wed, 2009-07-22 at 12:44 +0400, Igor Sysoev wrote:
> >>>>>On Tue, Jul 21, 2009 at 08:02:05PM +0200, Brice Figureau wrote:
> >>>>>
> >>>>>>Hi,
> >>>>>>
> >>>>>>For Puppet[1] Nginx deployement (that is using Nginx as a front-end 
> >>>>>>load-balancers to puppetmasters[2]), I had to create the following 
> >>>>>>two patches, to match Apache behaviour:
> >>>>>>
> >>>>>>* The first patch allows:
> >>>>>> + a new variant of ssl_client_verify: optional. In this mode, if the 
> >>>>>>client sends a certificate it is verified, but if the client doesn't 
> >>>>>>send a certificate, the connection is authorized too.
> >>>>>>
> >>>>>> + a new variable: $ssl_client_verify which contains, either NONE, 
> >>>>>>SUCCESS or FAILURE depending on the verification status. It can be 
> >>>>>>used to send information to the upstream about the client 
> >>>>>>verification.
> >>>>>>
> >>>>>>* The second patch adds CRL support to the client certificate 
> >>>>>>verification:
> >>>>>>
> >>>>>> ssl_crl /path/to/crl.pem;
> >>>>>>
> >>>>>>Nginx then verifies the client certificate hasn't been revoked in the 
> >>>>>>given CRL before allowing the connection to proceed.
> >>>>>>
> >>>>>>For access to the patches, please see my last blog article:
> >>>>>>http://www.masterzen.fr/2009/07/21/new-ssl-features-for-nginx/
> >>>>>>
> >>>>>>It would be great if those patches could be merged in the official 
> >>>>>>Nginx source tree.
> >>>>>Thank you, I have looked the patches, it was really surpise for me that
> >>>>>OpenSSL 0.9.7 supports CRL. I read in old enough book "Network Security
> >>>>>with OpenSSL" written when 0.9.7 was being developed, that OpenSSL has
> >>>>>no built-in CRL support. 
> >>>>Ah, ok. I based all my development on OpenSSL 0.9.8, since that's what
> >>>>I'm building Nginx againt. And definitely there is CRL support.
> >>>>Is OpenSSL 0.9.7 a strict dependency for Nginx?
> >>>No. I think this code should be just "#ifdef'ed X509_V_FLAG_CRL_CHECK".
> >>I'm OK with this. BTW, I checked and CRL support was added in 0.9.7.
> >>
> >>>>>Then I have looked in Apache's mod_ssl sources and
> >>>>>its CRL support seemed to me very heavy: mod_ssl does a lot of useless
> >>>>>operations.
> >>>>Which ones?
> >>>>What I don't get is why they're doing the CRL verification themselves.
> >>>Because mod_ssl were developed before 0.9.7.
> >>Yes, I do think so. But it's error-prone and certainly less efficient.
> >>
> >>>>I found this comment in the code:
> >>>>    * OpenSSL provides the general mechanism to deal with CRLs but does
> >>>>not
> >>>>    * use them automatically when verifying certificates, so we do it
> >>>>    * explicitly here. We will check the CRL for the currently checked
> >>>>    * certificate, if there is such a CRL in the store.
> >>>>
> >>>>This seems wrong to me, as I already tested, and it works fine at least
> >>>>in version 0.9.8.
> >>>Yes, this implementation. However, I made mistake: it's not too heavy as
> >>>it seemed to me first time I have looked.
> >>>
> >>>>>I think that it's enough to store hash of only public key of
> >>>>>all CRL certificates (including intermediate ones). 
> >>>>Why reinvent the wheel?
> >>>>The CRL is a standard thing (see RFC 3280), and basically this is a DER
> >>>>encoded ASN1 structure containing the list of the revoked certificates
> >>>>serial number, signed by the CA cert.
> >>>>
> >>>>>Have you looked
> >>>>>how CRL is implemented in OpenSSL ?
> >>>>Yes, I did. It is pretty extensive, and matches RFC3280.
> >>>>
> >>>>I'll fetch OpenSSL 0.9.7 to see if it supports or not CRL, but I'd be
> >>>>suprised it wouldn't.
> >>0.9.7 definitely supports CRL verification.
> >
> >Yes. When I mentioned the book, I meant that CRL were not supported
> >at least in 0.9.6.
> >
> >>>>Thanks for reviewing the patch (at least the first one could be merged,
> >>>>isn't it?).
> >>>Probabaly, I will commit the patches in next 0.8.7.
> >>Will you merge the CRL one (feel free to rewrite it if you prefer), too ?
> >
> >Yes, the single issue is name of directive: ssl_crl. Should it be longer 
> >and
> >more expressive ? Apache has SSLCARevocationFile.
> 
> Yes, the name is not very good but the other alternatives I thought 
> about were too long:
> ssl_certificate_revocation
> ssl_ca_revocation
> ssl_ca_certificate_revocation
> 
> Maybe the best one is: ssl_ca_revocation?
> But that'd be the only directive with CA in it, although that's what's 
> is really the ssl_client_certificate one.
> 
> So maybe, last try: ssl_client_revocation would be really better.
> 
> What do you think?

Probably, ssl_client_revocation is better.
Question to native speakers: should it be ssl_client_revocationS ?


-- 
Igor Sysoev
http://sysoev.ru/en/