Fix ipa-server-upgrade: This entry already exists

ipa-server-upgrade fails when running the ipaload_cacrt plugin. The plugin
finds all CA certificates in /etc/httpd/alias and uploads them in LDAP
below cn=certificates,cn=ipa,cn=etc,$BASEDN.
The issue happens because there is already an entry in LDAP for IPA CA, but
with a different DN. The nickname in /etc/httpd/alias can differ from
$DOMAIN IPA CA.

To avoid the issue:
1/ during upgrade, run a new plugin that removes duplicates and restarts ldap
(to make sure that uniqueness attr plugin is working after the new plugin)
2/ modify upload_cacert plugin so that it is using $DOMAIN IPA CA instead of
cn=$nickname,cn=ipa,cn=etc,$BASEDN when uploading IPA CA.

https://pagure.io/freeipa/issue/7125

Reviewed-By: Fraser Tweedale <ftweedal@redhat.com>

install/updates/90-post_upgrade_plugins.update

@@ -15,6 +15,7 @@ plugin: update_ca_renewal_master
 plugin: update_idrange_type
 plugin: update_pacs
 plugin: update_service_principalalias
+plugin: update_fix_duplicate_cacrt_in_ldap
 plugin: update_upload_cacrt
 # update_ra_cert_store has to be executed after update_ca_renewal_master
 plugin: update_ra_cert_store

ipalib/install/certstore.py

@@ -27,6 +27,7 @@ from pyasn1.error import PyAsn1Error
 from ipapython.dn import DN
 from ipapython.certdb import get_ca_nickname, TrustFlags
 from ipalib import errors, x509
+from ipalib.constants import IPA_CA_CN
 
 
 def _parse_cert(cert):
@@ -385,3 +386,21 @@ def get_ca_certs_nss(ldap, base_dn, compat_realm, compat_ipa_ca,
         nss_certs.append((cert, nickname, trust_flags))
 
     return nss_certs
+
+
+def get_ca_subject(ldap, container_ca, base_dn):
+    """
+    Look for the IPA CA certificate subject.
+    """
+    dn = DN(('cn', IPA_CA_CN), container_ca, base_dn)
+    try:
+        cacert_subject = ldap.get_entry(dn)['ipacasubjectdn'][0]
+    except errors.NotFound:
+        # if the entry doesn't exist, we are dealing with a pre-v4.4
+        # installation, where the default CA subject was always based
+        # on the subject_base.
+        attrs = ldap.get_ipa_config()
+        subject_base = attrs.get('ipacertificatesubjectbase')[0]
+        cacert_subject = DN(('CN', 'Certificate Authority'), subject_base)
+
+    return cacert_subject

ipaserver/install/plugins/update_fix_duplicate_cacrt_in_ldap.py

@@ -0,0 +1,84 @@
+# Authors:
+#   Florence Blanc-Renaud <flo@redhat.com>
+#
+# Copyright (C) 2017  Red Hat
+# see file 'COPYING' for use and warranty information
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import logging
+
+from ipalib import Registry, errors
+from ipalib import Updater
+from ipalib.install import certstore
+from ipapython.dn import DN
+from ipapython.certdb import get_ca_nickname
+
+logger = logging.getLogger(__name__)
+
+register = Registry()
+
+
+@register()
+class update_fix_duplicate_cacrt_in_ldap(Updater):
+    """
+    When multiple entries exist for IPA CA cert in ldap, remove the duplicate
+
+    After this plugin, ds needs to be restarted. This ensures that
+    the attribute uniqueness plugin is working and prevents
+    other plugins from adding duplicates.
+    """
+
+    def execute(self, **options):
+        # If CA is disabled, no need to check for duplicates of IPA CA
+        ca_enabled = self.api.Command.ca_is_enabled()['result']
+        if not ca_enabled:
+            return True, []
+
+        # Look for the IPA CA cert subject
+        ldap = self.api.Backend.ldap2
+        cacert_subject = certstore.get_ca_subject(
+            ldap,
+            self.api.env.container_ca,
+            self.api.env.basedn)
+
+        # Find if there are other certificates with the same subject
+        # They are duplicates resulting of BZ 1480102
+        base_dn = DN(('cn', 'certificates'), ('cn', 'ipa'), ('cn', 'etc'),
+                     self.api.env.basedn)
+        try:
+            filter = ldap.make_filter({'ipaCertSubject': cacert_subject})
+            result, _truncated = ldap.find_entries(
+                base_dn=base_dn,
+                filter=filter,
+                attrs_list=[])
+        except errors.NotFound:
+            # No duplicate, we're good
+            logger.debug("No duplicates for IPA CA in LDAP")
+            return True, []
+
+        logger.debug("Found %d entrie(s) for IPA CA in LDAP", len(result))
+        cacert_dn = DN(('cn', get_ca_nickname(self.api.env.realm)), base_dn)
+        for entry in result:
+            if entry.dn == cacert_dn:
+                continue
+            # Remove the duplicate
+            try:
+                ldap.delete_entry(entry)
+                logger.debug("Removed the duplicate %s", entry.dn)
+            except Exception as e:
+                logger.warning("Failed to remove the duplicate %s: %s",
+                               entry.dn, e)
+
+        return True, []

ipaserver/install/plugins/upload_cacrt.py

@@ -45,6 +45,10 @@ class update_upload_cacrt(Updater):
         ca_enabled = self.api.Command.ca_is_enabled()['result']
         if ca_enabled:
             ca_nickname = certdb.get_ca_nickname(self.api.env.realm)
+            ca_subject = certstore.get_ca_subject(
+                self.api.Backend.ldap2,
+                self.api.env.container_ca,
+                self.api.env.basedn)
         else:
             ca_nickname = None
             server_certs = db.find_server_certs()
@@ -58,9 +62,17 @@ class update_upload_cacrt(Updater):
         for nickname, trust_flags in db.list_certs():
             if trust_flags.has_key:
                 continue
-            if nickname == ca_nickname and ca_enabled:
-                trust_flags = certdb.IPA_CA_TRUST_FLAGS
             cert = db.get_cert_from_db(nickname)
+            subject = cert.subject
+            if ca_enabled and subject == ca_subject:
+                # When ca is enabled, we can have the IPA CA cert stored
+                # in the nss db with a different nickname (for instance
+                # when the server was installed with --subject to
+                # customize the CA cert subject), but it must always be
+                # stored in LDAP with the DN cn=$DOMAIN IPA CA
+                # This is why we check the subject instead of the nickname here
+                nickname = ca_nickname
+                trust_flags = certdb.IPA_CA_TRUST_FLAGS
             trust, _ca, eku = certstore.trust_flags_to_key_policy(trust_flags)
 
             dn = DN(('cn', nickname), ('cn', 'certificates'), ('cn', 'ipa'),