[Freeipa-devel] FreeIPA and modern requirements on certificates

[Rob Crittenden]

Alexander Bokovoy wrote:
> On Fri, 08 Jan 2016, Martin Kosek wrote:
>> On 01/08/2016 02:17 PM, Fraser Tweedale wrote:
>>> On Fri, Jan 08, 2016 at 02:02:07PM +0100, Martin Kosek wrote:
>>>> On 01/08/2016 01:56 PM, Fraser Tweedale wrote:
>>>>> On Fri, Jan 08, 2016 at 01:26:57PM +0100, Martin Kosek wrote:
>>>>>> Hi Fraser and other X.509 SMEs,
>>>>>>
>>>>>> I wanted to check with you on what we have or plan to have with
>>>>>> respect to
>>>>>> certificate/cipher strength in FreeIPA.
>>>>>>
>>>>>> When I visit the FreeIPA public demo for example, I usually see
>>>>>> following
>>>>>> errors with recent browsers:
>>>>>>
>>>>>> * Your connection to ipa.demo1.freeipa.org is encrypted using
>>>>>> obsolete cypher
>>>>>> suite.
>>>>>>  - The connection uses TLS 1.2
>>>>>>  - The connection is encrypted ising AES_128_CBC, with HMAC-SHA1
>>>>>> for message
>>>>>> authentication and RSA as the key exchange mechanism
>>>>>>
>>>>> This is a cipher suite / ordering issue, not related to certificate.
>>>>>
>>>>>> I usually do not see the common
>>>>>> * Certificate chain contains a certificate signed with SHA-1
>>>>>> error, but I am not sure if we are covered for this one.
>>>>>>
>>>>> We are using sha256 for IPA CA and default profiles.  Customers
>>>>> could still modify the profile or add profiles to sign using an
>>>>> obsolete hash, if they wanted to, but our default is good.
>>>>>
>>>>>>
>>>>>> When I tested the FreeIPA demo with
>>>>>> https://www.ssllabs.com/ssltest/analyze.html?d=ipa.demo1.freeipa.org
>>>>>> (and ignore the trust issues), we get the mark B with following
>>>>>> warnings:
>>>>>>
>>>>>> * This server accepts RC4 cipher, but only with older protocol
>>>>>> versions. Grade
>>>>>> capped to B.
>>>>>>
>>>>>> * The server does not support Forward Secrecy with the reference
>>>>>> browsers.
>>>>>>
>>>>> Again a cipher suite tweak will address this.
>>>>>
>>>>>>
>>>>>> What do we miss to turn out Grade A, which is obviously something
>>>>>> expected from
>>>>>> security solution like FreeIPA? Is it just about ECC support
>>>>>> (https://fedorahosted.org/freeipa/ticket/3951) or also maybe some
>>>>>> change to our
>>>>>> default certificate profiles?
>>>>>>
>>>>> Based on what you've written, it is just the cipher suite that needs
>>>>> changing, and maybe a setting about favouring server cipher order
>>>>> over client order.  ECC certificate support is not needed (yet) and
>>>>> the default profile is fine, w.r.t. hash used for signing.
>>>>>
>>>>> One important modern certificate requirement is to always include a
>>>>> SAN dnsName for the subject, as required by RFC 2818; this is ticket
>>>>> #4970 and it is on my radar.
>>>>>
>>>>> Cheers,
>>>>> Fraser
>>>>
>>>> Should I then file a ticket to fix the cipher suite? (I did not fully
>>>> understand the specifics though).
>>>>
>>> Yes.  I have not checked yet, but we are possibly using
>>> stock-standard mod_nss configuration (as shipped by the RPM).  If
>>> so, we should file a ticket against mod_nss to improve their
>>> defaults.
>>
>> Right. In nss.conf, I see this default cipher suite:
>>
>> NSSCipherSuite
>> +rsa_rc4_128_md5,+rsa_rc4_128_sha,+rsa_3des_sha,-rsa_des_sha,-rsa_rc4_40_md5,-
>>
>>
>> rsa_rc2_40_md5,-rsa_null_md5,-rsa_null_sha,+fips_3des_sha,-fips_des_sha,-fortezza,-fortezza_rc4_128_sha,-fortezza_null,-rsa_des_56_sha,-rsa_rc4_56_sha,+rsa_aes_128_sha,+rsa_aes_256_sha
>>
>>
>> It certainly makes me little nervous. In 389-ds-base case, we had a
>> similar
>> list and solved it my using the list directly from NSS:
>>
>> https://fedorahosted.org/389/ticket/47838
>> https://fedorahosted.org/freeipa/ticket/4395
>>
>> CCing Rob here.
> Here is what I have in my setup that goes to A- according to ssllabs:
> NSSCipherSuite
> -rsa_rc4_128_md5,-rsa_rc4_128_sha,+rsa_3des_sha,-rsa_des_sha,-rsa_rc4_40_md5,-rsa_rc2_40_md5,-rsa_null_md5,-rsa_null_sha,+fips_3des_sha,-fips_des_sha,-fortezza,-fortezza_rc4_128_sha,-fortezza_null,-rsa_des_56_sha,-rsa_rc4_56_sha,+rsa_aes_128_sha,+rsa_aes_256_sha
> 
> 
> NSSProtocol TLSv1.0,TLSv1.1,TLSv1.2
> 
> This gets A- due to lack of forward secrecy support.
> 

An IPA ticket for this exists, https://fedorahosted.org/freeipa/ticket/4431

For mod_nss I was going to do this as part of
https://fedorahosted.org/mod_nss/ticket/5

If you add in some EC ciphers you'd probably get PFS too. DH ciphers
aren't supported yet.

rob