host: update System: Manage Host Keytab permission

Since commit 5c0e7a5, a new extended
operation to get a keytab is supposed to be used. This keytab
setting/retrieval extended operation checks access rights of the bound
DN to write to a virtual attribute 'ipaProtectedOperation;write_keys'.

If the write isn't allowed, the operation is rejected and ipa-getkeytab
tool falls back to an older code that generates the keytab on the client
and forcibly sets to the LDAP entry. For the latter, a check is done to
make sure the bound DN is allowed to write to 'krbPrincipalKey' attribute.

This fallback should never happen for newer deployments. When enrollemnt
operation is delegated to non-administrative user with the help of 'Host
Enrollment' role, a host can be pre-created or created at enrollment
time, if this non-administrative user has 'Host Administrators' role. In
the latter case a system permission 'System: Manage Host Keytab' grants
write access to 'krbPrincipalKey' attribute but lacks any access to the
virtual attributes expected by the new extended operation.

There is a second virtual attribute, 'ipaProtectedOperation;read_keys',
that allows to retrieve existing keys for a host. However, during
initial enrollment we do not allow to retrieve and reuse existing
Kerberos key: while 'ipa-getkeytab -r' would give ability to retrieve
the existing key, 'ipa-join' has no way to trigger that operation.
Hence, permission 'System: Manage Host Keytab' will not grant the right
to read the Kerberos key via extended operation used by 'ipa-getkeytab
-r'. Such operation can be done later by utilizing 'ipa
service/host-allow-retrieve-keytab' commands.

Fix 'System: Manage Host Keytab' permission and extend a permission test
to see that we do not fallback to the old extended operation.

Fixes: https://pagure.io/freeipa/issue/9496

Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ACI.txt

@@ -147,7 +147,7 @@ aci: (targetattr = "usercertificate")(targetfilter = "(objectclass=ipahost)")(ve
 dn: cn=computers,cn=accounts,dc=ipa,dc=example
 aci: (targetattr = "userpassword")(targetfilter = "(objectclass=ipahost)")(version 3.0;acl "permission:System: Manage Host Enrollment Password";allow (write) groupdn = "ldap:///cn=System: Manage Host Enrollment Password,cn=permissions,cn=pbac,dc=ipa,dc=example";)
 dn: cn=computers,cn=accounts,dc=ipa,dc=example
-aci: (targetattr = "krblastpwdchange || krbprincipalkey")(targetfilter = "(&(!(memberOf=cn=ipaservers,cn=hostgroups,cn=accounts,dc=ipa,dc=example))(objectclass=ipahost))")(version 3.0;acl "permission:System: Manage Host Keytab";allow (write) groupdn = "ldap:///cn=System: Manage Host Keytab,cn=permissions,cn=pbac,dc=ipa,dc=example";)
+aci: (targetattr = "ipaprotectedoperation;write_keys || krblastpwdchange || krbprincipalkey")(targetfilter = "(&(!(memberOf=cn=ipaservers,cn=hostgroups,cn=accounts,dc=ipa,dc=example))(objectclass=ipahost))")(version 3.0;acl "permission:System: Manage Host Keytab";allow (write) groupdn = "ldap:///cn=System: Manage Host Keytab,cn=permissions,cn=pbac,dc=ipa,dc=example";)
 dn: cn=computers,cn=accounts,dc=ipa,dc=example
 aci: (targetattr = "createtimestamp || entryusn || ipaallowedtoperform;read_keys || ipaallowedtoperform;write_keys || modifytimestamp || objectclass")(targetfilter = "(objectclass=ipahost)")(version 3.0;acl "permission:System: Manage Host Keytab Permissions";allow (compare,read,search,write) groupdn = "ldap:///cn=System: Manage Host Keytab Permissions,cn=permissions,cn=pbac,dc=ipa,dc=example";)
 dn: cn=computers,cn=accounts,dc=ipa,dc=example

ipaserver/plugins/host.py

@@ -409,7 +409,8 @@ class host(LDAPObject):
                                         api.env.container_hostgroup,
                                         api.env.basedn),
             ],
-            'ipapermdefaultattr': {'krblastpwdchange', 'krbprincipalkey'},
+            'ipapermdefaultattr': {'krblastpwdchange', 'krbprincipalkey',
+                                   'ipaprotectedoperation;write_keys'},
             'replaces': [
                 '(targetattr = "krbprincipalkey || krblastpwdchange")(target = "ldap:///fqdn=*,cn=computers,cn=accounts,$SUFFIX")(version 3.0;acl "permission:Manage host keytab";allow (write) groupdn = "ldap:///cn=Manage host keytab,cn=permissions,cn=pbac,$SUFFIX";)',
             ],

ipatests/test_integration/test_user_permissions.py

@@ -277,6 +277,9 @@ def test_installclient_as_user_admin(self):
         self.master.run_command(['ipa', 'privilege-add-permission',
                                  '--permissions', 'System: Add Hosts',
                                  'Add Hosts'])
+        self.master.run_command(['ipa', 'privilege-add-permission',
+                                 '--permissions', 'System: Manage Host Keytab',
+                                 'Add Hosts'])
 
         self.master.run_command(['ipa', 'role-add-privilege', 'useradmin',
                                  '--privileges', 'Host Enrollment'])
@@ -301,6 +304,10 @@ def test_installclient_as_user_admin(self):
                                                encoding='utf-8')
         assert msg in install_log
 
+        # Make sure we do not fallback to an old keytab retrieval method anymore
+        msg = "Retrying with pre-4.0 keytab retrieval method..."
+        assert msg not in install_log
+
         # check that user is able to request a host cert, too
         result = tasks.run_certutil(client, ['-L'], paths.IPA_NSSDB_DIR)
         assert 'Local IPA host' in result.stdout_text