11:53 a.m.
On 8/5/2015 10:11 AM, Christian Heimes wrote:
Hi,
this mail is about my take on issue https://fedorahosted.org/pki/ticket/1253
Yesterday night I had a long conversation with Ade on #dogtag-pki. He
explained the install process in great detail to me. Thanks Ade! :) Do
we have a logging bot in the channel or another way to store discussions
for the future?
Today I took the scenic route and explored the implementation of
pkispawn as well as how it interacts with Tomcat over HTTPS.
I hope you enjoyed the view :)
Ade already
pointed three distinct cases. There might be a couple more case, though.
I haven't tried them all yet.
I'm not fully familiar with the process, but I have some comments below.
Case #1: creation of security domain
------------------------------------
The first case occurs during the initial installation of the security
domain, when no CA cert is imported. During the installation pkispawn
setups up a Tomcat instances and creates a CA. Because no CA exists in
the beginning of the process, the installer uses a temporary self-signed
cert for the Tomcat server instance. The self-signed cert is stored in
PKI's NSS database. The name of the certificate for instance
'pki-tomcat' is 'Server-Cert cert-pki-tomcat'. This certificate is used
throughout the entire installation until Tomcat is restarted.
# certutil -d /etc/pki/pki-tomcat/alias/ -L
Certificate Nickname Trust
Attributes
SSL,S/MIME,JAR/XPI
Server-Cert cert-pki-tomcat CTu,Cu,Cu
# certutil -d /etc/pki/pki-tomcat/alias/ -L \
-a -n 'Server-Cert cert-pki-tomcat' | openssl x509 -text
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 0 (0x0)
Signature Algorithm: sha256WithRSAEncryption
Issuer: O=2015-08-05 14:11:10, CN=vm-089.example.com
Validity
Not Before: Aug 5 12:13:05 2015 GMT
Not After : Aug 5 12:13:05 2016 GMT
Subject: O=2015-08-05 14:11:10, CN=vm-089.example.com
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (2048 bit)
Modulus:
After pkispawn has successfully spawned the CA, the trust anchor is
available in NSS database, too. Its name is 'caSigningCert
cert-pki-tomcat CA' for 'pki-tomcat'. 'Server-Cert cert-pki-tomcat'
is
replaced with a signed cert.
# certutil -d /etc/pki/pki-tomcat/alias/ -L
Certificate Nickname Trust
Attributes
SSL,S/MIME,JAR/XPI
caSigningCert cert-pki-tomcat CA CTu,Cu,Cu
Server-Cert cert-pki-tomcat u,u,u
auditSigningCert cert-pki-tomcat CA u,u,Pu
ocspSigningCert cert-pki-tomcat CA u,u,u
subsystemCert cert-pki-tomcat u,u,u
# certutil -d /etc/pki/pki-tomcat/alias/ -L -a -n \
'caSigningCert cert-pki-tomcat CA' | openssl x509 -text
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 1 (0x1)
Signature Algorithm: sha256WithRSAEncryption
Issuer: O=example.com Security Domain, CN=CA Signing Certificate
Validity
Not Before: Aug 5 12:26:52 2015 GMT
Not After : Aug 5 12:26:52 2035 GMT
Subject: O=example.com Security Domain, CN=CA Signing Certificate
# certutil -d /etc/pki/pki-tomcat/alias/ -L -a -n \
'Server-Cert cert-pki-tomcat' | openssl x509 -text
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 3 (0x3)
Signature Algorithm: sha256WithRSAEncryption
Issuer: O=example.com Security Domain, CN=CA Signing Certificate
Validity
Not Before: Aug 5 12:26:52 2015 GMT
Not After : Jul 25 12:26:52 2017 GMT
Subject: O=example.com Security Domain, CN=vm-089.example.com
I suppose if LDAPS is required, the DS trust anchor would have to be
provided before running pkispawn.
Case #2: new subsystem on the same host
---------------------------------------
For new subsystems on the same host, pkispawn simply has to trust the CA
Signing Certificate from #1. The same is true for the 389-DS server cert.
If the new subsystem is in the same instance as the CA, they will share
the same NSS database, so I suppose there's no additional steps required
to trust the CA/DS certs.
If the new subsystem is in a different instance, it will require
exporting into PKCS #12 file as in case #3.
Case #3: subsystem on different host
------------------------------------
When a new subsystem is installed on a different host, the user must
provide the trust anchor for 389-DS out-of-band.
And some other CA certs too.
A user could also use
plain LDAP, but let's not go there.
To my understanding LDAPS is optional. The DS might be local and secured
in some ways that a plain LDAP connection is acceptable.
The trust anchor for the LDAP cert
might be the same as the trust anchor for the security domain -- or it
might be a different one. In both cases it's probably easier to grab the
trust anchor from LDAP. The LDAP connection is set up before pkispawn
does the first HTTPS request.
Do you want to get the trust anchors with LDAPS or a plain LDAP? If
LDAPS, doesn't it mean you need to have the trust anchors already?
Since we will be transporting some CA certs & keys via PKCS #12 anyway,
we might as well include the DS trust anchor there.
Case #4: clone on different host
--------------------------------
For installations of a clone or subsystem, the trust anchor must be
provided out-of-band. For a cloning setup
http://pki.fedoraproject.org/wiki/Cloning_Setup the PKCS#12 file should
contain all necessary information. It might also be possible to grab the
cert from LDAP like in case #3.
I think this is identical to case #3.
Case #5: security domain with imported CA
-----------------------------------------
I haven't tried to configure a CA with an externally managed and
imported trust anchor yet. Does anybody happen to know the nickname of
the cert and its trust anchor?
Not sure, but I think an external CA cert can be included in the same
PKCS #12 file.
Conclusion
==========
In case #1 pkispawn should dump the self-signed cert from NSS DB to PEM
file. requests can then load the self-signed cert as CA cert. For
self-signed certs this makes the cert trusted. The file should be
removed at the end of the installation.
Right. Additionally, at the end of installation we probably should
export the trust anchors into PEM and store it at a standard location
(e.g. SSL_CERT_DIR) so all applications can use it immediately.
In case #2 pkispawn should dump the trust anchor from the NSS
database
to a PEM file, too. I suggest to put the PEM file in a location where it
can be read by everybody. /etc/pki/pki-tomcat is only accessible by root
and members of the pkiuser group. It has no X bit for other.
If the subsystem is installed on the same host, the trust anchors should
already be available in the default location.
In case #3 the cert must either be provided out-of-band or grabbed
from
LDAP. I like the idea to grab it from LDAP and have an official API to
do so. Other systems like FreeIPA could use the same API, too. Like in
case #2 the cert should be dumped to a public-readable location.
If the subsystem is installed on a different host, the trust anchors
should be exported from the PKCS #12 into the standard location on that
host.
We could handle case #2 and #3 the same way and always grab the
trust
anchor from LDAP. It's less code and more robust, too.
As mentioned above, since we'll be transporting PKCS #12 file anyway,
I'm not sure if we should/can use LDAP.
Open question
-------------
1) Is there a stable and easy way to find the trust anchor in LDAP? In
my test setup the trust anchor has subjectName='CN=CA Signing
Certificate,O=example.com Security Domain'. Is the name always similar?
I'm not sure if that is guaranteed. A better way would be to retrieve
the actual cert used by the subsystem by its tag/nickname:
https://fedorahosted.org/pki/ticket/1473
2) Does anybody know how case #5 affects the nickname or subjectName
attribute of the trust anchor?
Not very familiar with this case.
Christian
--
Endi S. Dewata