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CA_certificate_renewal

CA_certificate_renewal#

Overview#

Allow automated and manual renewal of IPA CA certificate. Provide an utility for manual renewal, including modification of chaining (self-signed vs. signed by external CA). Store multiple CA certificates in LDAP and distribute them to clients.

This page describes phase 1 of the CA certificate management feature, which consists of automated and manual CA certificate renewal, CA certificate management utility and storage of multiple CA certificate in LDAP. Visit V4/CA certificate renewal (2) for description of phase 2, which consists of distribution of CA certificates to IPA clients.

Use Cases#

Automated CA certificate renewal#

When the CA certificate is nearing its expiration time, it should be automatically renewed. The renewed certificate will use the same keypair and subject name as the old certificate.

This only works for self-signed CA certificates in CA-ful installs.

Manual CA certificate renewal#

Allow admin to manually renew the CA certificate and possibly change its chaining (self-signed → signed by external CA, signed by external CA → self-signed, signed by external CA → signed by other external CA) (phase 1) and have the renewed certificate automatically distributed to all systems in the domain (phase 2). The renewed certificate will use the same keypair and subject name as the old certificate.

This works for any CA certificate in CA-ful installs.

Manual install of CA certificate#

In CA-less installs, CA certificate renewal is completely in charge of a 3rd party CA. Provide means of installing CA certificates obtained from such a CA (phase 1) and automatically distribute them to all systems in the domain (phase 2).

Design#

Shared certificate store#

CA certificates will be stored in entries under cn=certificates,cn=ipa,cn=etc,suffix:

 dn: cn=EXAMPLE.COM IPA CA,cn=certificates,cn=ipa,cn=etc,suffix
objectClass: ipaCertificate
objectClass: pkiCA
objectClass: ipaKeyPolicy
cn: cn=EXAMPLE.COM IPA CA
ipaCertSubject: CN=Certificate Authority,O=EXAMPLE.COM
ipaCertIssuerSerial: CN=Certificate Authority,O=EXAMPLE.COM;1
ipaCertIssuerSerial: CN=Certificate Authority,O=EXAMPLE.COM;22
 ipaPublicKey: DER-encoded public key
ipaConfigString: ipaCA
ipaConfigString: compatCA
 cACertificate;binary:: DER-encoded certificate 1
 cACertificate;binary:: DER-encoded certificate 2
ipaKeyTrust: trusted
ipaKeyExtUsage: 1.3.6.1.5.5.7.3.1
ipaKeyExtUsage: 1.3.6.1.5.5.7.3.2
ipaKeyExtUsage: 1.3.6.1.5.5.7.3.3
ipaKeyExtUsage: 1.3.6.1.5.5.7.3.4

Each entry represents a set of certificates using a single subject name and public key and contains trust policy for the set of certificates (based on p11-kit trust policy). The attributes are:

  • cn

    Nickname for the certificates. The value must be unique in the store.

  • ipaCertSubject

    Subject name of the certificates. The value must be unique in the store. Semicolons in the subject name are escaped as \3b.

  • ipaCertIssuerSerial

    Issuer name and serial number of each certificate in the set, separated by semicolon. Each value must be unique in the store. Semicolons in the issuer name are escaped as \3b.

  • `ipaPublicKey <V4/PKCS11_in_LDAP/Schema#Encoded_key_data>`__

    Public key of the certificates as DER-encoded SubjectPublicKeyInfo.

  • ipaConfigString

    Configuration flags:

    • ipaCA

      This entry represents the IPA CA certificate.

    • compatCA

      When a new certificate is added to the set, update

      cn=CAcert,cn=ipa,cn=etc,suffix with it.

  • cACertificate

    Each of the certificates in the set in DER encoding.

  • ipaKeyTrust

    Trust setting for the certificates:

    • unknown (default)

      Trust is not explicitly given. If there is other source of trust information, it should be used instead.

    • trusted

      The certificates in the set are explicitly trusted.

    • distrusted

      The certificates in the set are explicitly distrusted.

  • ipaKeyUsage

    Allowed key usages for the certificates as purpose bit names from the key usage certificate extension (see 5280, section 4.2.1.3). A value of none means no key usages are allowed. Default value is the value of the key usage extension from each certificate.

  • ipaKeyExtUsage

    Allowed extended key usages as key purpose OIDs (see 5280, section 4.2.1.12). A value of 1.3.6.1.4.1.3319.6.10.16 means no extended key usages are allowed. Default value is the value of the extended key usage extension from each certificate. For trusted CA certificates, the value of this attribute is mapped to NSS / certutil trust flags as follows:

    • 1.3.6.1.5.5.7.3.1 ⇒ C,,

    • 1.3.6.1.5.5.7.3.2 ⇒ T,,

    • 1.3.6.1.5.5.7.3.3 ⇒ ,,C

    • 1.3.6.1.5.5.7.3.4 ⇒ ,C,

The entries will be readable by everyone and writable only by the directory manager (for installers and management tools) and the server host (for automatic renewal).

The new schema used for the entries is:

attributeTypes: (2.16.840.1.113730.3.8.11.???
                 NAME 'ipaCertSubject'
                 DESC 'Subject name'
                 EQUALITY caseIgnoreMatch
                 SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
                 SINGLE-VALUE
                 X-ORIGIN 'IPA v4' )
attributeTypes: (2.16.840.1.113730.3.8.11.???
                 NAME 'ipaCertIssuerSerial'
                 DESC 'Issuer name and serial number'
                 EQUALITY caseIgnoreMatch
                 SUBSTR caseIgnoreSubstringsMatch
                 SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
                 X-ORIGIN 'IPA v4' )
attributeTypes: (2.16.840.1.113730.3.8.11.???
                 NAME 'ipaKeyTrust'
                 DESC 'Key trust (unknown, trusted, distrusted)'
                 EQUALITY caseIgnoreMatch
                 SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
                 X-ORIGIN 'IPA v4')
attributeTypes: (2.16.840.1.113730.3.8.11.???
                 NAME 'ipaKeyUsage'
                 DESC 'Allowed key usage'
                 EQUALITY caseIgnoreMatch
                 SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
                 X-ORIGIN 'IPA v4')
attributeTypes: (2.16.840.1.113730.3.8.11.???
                 NAME 'ipaKeyExtUsage'
                 DESC 'Allowed extended key usage'
                 EQUALITY objectIdentifierMatch
                 SYNTAX 1.3.6.1.4.1.1466.115.121.1.38
                 X-ORIGIN 'IPA v4')
objectClasses: (2.16.840.1.113730.3.8.12.???
                NAME 'ipaCertificate'
                SUP top STRUCTURAL
                MUST ( cn $ ipaCertSubject $ ipaCertIssuerSerial $ ipaPublicKey )
                MAY  ( ipaConfigString )
                X-ORIGIN 'IPA v4' )
objectClasses: (2.16.840.1.113730.3.8.12.???
                NAME 'ipaKeyPolicy'
                SUP top AUXILIARY
                MAY  ( ipaKeyTrust $ ipaKeyUsage $ ipaExtKeyUsage )
                X-ORIGIN 'IPA v4')

Automatic renewal of IPA CA certificate#

The CA certificate managed by Dogtag will be tracked by certmonger. If the certificate is self-signed, it will be automatically renewed. If the certificate is signed by an external CA, the renewal attempt will fail with an error, advising the administrator to renew the certificate manually. The error is syslogged with ALERT severity.

CA certificate management utility#

There will be new utility to manage CA certificates, ipa-cacert-manage. It will have several subcommands:

  • renewoptions

    This command will be available only for CA-ful installs and will be used to renew the IPA CA certificate. The certificate can be renewed either as self-signed or signed by an external CA. By default, the chaining used for the old certificate is used for the new certificate as well. Renewing a CA certificate signed by an external CA is a 2 step operation: in the first step, a CSR is exported to /var/lib/ipa/ca.csr; in the second step, the signed certificate is installed. The available options are:

    • --self-signed

      Renew the CA certificate as self-signed.

    • --external-ca

      Renew the CA certificate as signed by an external CA, step 1: Export CSR to /var/lib/ipa/ca.csr.

    • --external-cert-filefile

      Renew the CA certificate as signed by an external CA, step 2: Install the new CA certificate.

    • --passwordpassword

      Directory manager password. Required for external CA renewal step 2.

  • installoptions``*\ \ *``file

    Install CA certificate from a PEM file. The available options are:

    • -nnickname``*, ``--nicknamenickname

      Nickname for the certificate.

    • -tflags``*, ``--trust-flagsflags

      Trust flags for the certificate in NSS / certutil format.

Client certificate update utility#

There will be new utility, ipa-certupdate, for updating CA certificates on clients with up-to-date data from LDAP. Until phase 2 is complete, running it manually will be the only way to update the CA certificates after installation.

Implementation#

In CA-ful installs, CA certificate renewal is handled by certmonger. Automatic renewal is handled by certmonger itself. In manual renewal, ipa-cacert-manage resubmits the certmonger request for the CA certificate. If the CA certificate is self-signed, the request is submitted directly to Dogtag. If the CA certificate is signed by an external CA, ipa-cacert-manage exports the CSR created by certmonger to /var/lib/ipa/ca.csr in the first step. In the seconds step, it updates cn=ca_renewal,cn=ipa,cn=etc,suffix so that the new CA certificate can be picked up by certmonger and resubmits the certmonger request. In the post-save command of the certmonger request, the renewed CA certificate is added to cn=certificates,cn=ipa,cn=etc,suffix.

When installing new CA certificate manually, ipa-cacert-manage adds the certificate directly to cn=certificates,cn=ipa,cn=etc,suffix.

When a CA certificate is renewed, its previous version is not removed to allow rollover.

Feature Management#

UI

N/A

CLI

See design.

Installers#

N/A

Upgrade#

Old clients will look for IPA CA certificate in cn=CAcert,cn=ipa,cn=etc,suffix. A copy of the most recent IPA CA certificate needs to be maintained in this entry for compatibility with old clients.

Old servers do not have cn=certificates,cn=ipa,cn=etc,suffix``*. Client installer has to look for CA certificates both in this entry and in ``cn=CAcert,cn=ipa,cn=etc,suffix for compatibility with old servers.

How to Test#

Automated CA certificate renewal#

  1. Install IPA server with CA (either self-signed or signed by external CA)

  2. Get the expiration date of the IPA CA certificate:

    # getcert list -d /etc/pki/pki-tomcat/alias -n 'caSigningCert cert-pki-ca'

  3. Move system time 3 weeks before the expiration date

  4. Check the status of the certmonger request:

    # getcert list -d /etc/pki/pki-tomcat/alias -n 'caSigningCert cert-pki-ca'

  5. If the IPA CA was installed self-signed:

    1. Wait for the certmonger request to complete, it should end up with MONITORING status

    2. Check that the renewed CA certificate was added to the LDAP certificate store and to the /etc/pki/pki-tomcat/alias NSS database

  6. If the IPA CA was installed signed by external CA:

    1. Wait for the certmonger request to complete, it should end up with CA_WORKING status

    2. Check that an error was syslogged with ALERT severity

Manual CA certificate renewal#

  1. Install IPA server with CA (either self-signed or signed by external CA)

  2. To renew the IPA CA certificate as self-signed:

    1. Run ipa-cacert-manage renew, if the IPA CA was not installed self-signed, add the --self-signed option

    2. Wait for the command to complete

    3. Check that the renewed CA certificate was added to the LDAP certificate store and to the /etc/pki/pki-tomcat/alias NSS database

  3. To renew the IPA CA certificate as signed by external CA:

    1. Run ipa-cacert-manage renew, if the IPA CA was not installed signed by external CA, add the --external-ca option

    2. The command will produce a CSR file at /var/lib/ipa/ca.csr

    3. Sign the CSR file with the external CA to get the renewed CA certificate

    4. Run ipa-cacert-manage renew, specify the renewed CA certificate and external CA certificate chain files in the --external-cert-file option

    5. Wait for the command to complete

    6. Check that the renewed CA certificate and the external CA certificate were added to the LDAP certificate store and to the /etc/pki/pki-tomcat/alias NSS database

Manual install of CA certificate#

  1. Install IPA server

  2. Run ipa-cacert-manage install to install the CA certificate

  3. Check that the certificate was added to the LDAP certificate store

Manual update of local CA certificate files#

  1. Install IPA server(s) and possibly client(s)

  2. Renew or install CA certificate(s)

  3. Run ipa-certupdate on either a server or a client

  4. Check that the /etc/ipa/nssdb and /etc/pki/nssdb NSS databases and the /etc/ipa/ca.crt file were updated with CA certificates from the LDAP certificate store

  5. If on a server, additionaly check that the /etc/dirsrv/slapd-REALM and /etc/httpd/alias NSS databases and the /usr/share/ipa/html/ca.crt file were updated as well

  6. If on a server with a CA, additionaly check that the /etc/pki/pki-tomcat/alias NSS database was updated as well

Test Plan#

TODO

RFE Author#

Jan Cholasta

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