Implement support for non-LDAP-based actions that use the LDAP ACI subsystem.

There are some operations, like those for the certificate system, that
don't need to write to the directory server. So instead we have an entry
that we test against to determine whether the operation is allowed or not.

This is done by attempting a write on the entry. If it would succeed then
permission is granted. If not then denied. The write we attempt is actually
invalid so the write itself will fail but the attempt will fail first if
access is not permitted, so we can distinguish between the two without
polluting the entry.

1 files changed, 73 insertions, 0 deletions

diff --git a/ipalib/plugins/virtual.py b/ipalib/plugins/virtual.py
new file mode 100644
index 000000000..a1dfbdf68
--- /dev/null
+++ b/ipalib/plugins/virtual.py
@@ -0,0 +1,73 @@
+# Authors:
+#   Rob Crittenden <rcritten@redhat.com>
+#
+# Copyright (C) 2009  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; version 2 only
+#
+# 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, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+"""
+Base classes for non-LDAP backend plugins.
+"""
+from ipalib import api
+from ipalib import Command
+from ipalib import errors
+
+class VirtualCommand(Command):
+    """
+    A command that doesn't use the LDAP backend but wants to use the
+    LDAP access control system to make authorization decisions.
+
+    The class variable operation is the commonName attribute of the
+    entry to be tested against.
+
+    In advance, you need to create an entry of the form:
+        cn=<operation>, api.env.container_virtual, api.env.basedn
+
+    Ex.
+        cn=request certificate, cn=virtual operations, dc=example, dc=com
+    """
+    operation = None
+
+    def execute(self, *args, **kw):
+        """
+        Perform the LDAP query to determine authorization.
+
+        This should be executed via super() before any actual work is done.
+        """
+        if self.operation is None:
+            raise errors.ACIError(info='operation not defined')
+
+        ldap = self.api.Backend.ldap
+        self.log.info("IPA: virtual verify %s" % self.operation)
+
+        operationdn = "cn=%s,%s,%s" % (self.operation, self.api.env.container_virtual, self.api.env.basedn)
+
+        # By adding this unknown objectclass we do several things.
+        # DS checks ACIs before the objectclass so we can test for ACI
+        # errors to know if we have rights. If we do have rights then the
+        # update will fail anyway with a Database error because of an
+        # unknown objectclass, so we can catch that gracefully as well.
+        try:
+            updatekw = {'objectclass': ['somerandomunknownclass']}
+            ldap.update(operationdn, **updatekw)
+        except errors.ACIError, e:
+            self.log.debug("%s" % str(e))
+            raise errors.ACIError(info='not allowed to perform this command')
+        except errors.DatabaseError:
+            return
+        except Exception, e:
+            # Something unexpected happened. Log it and deny access to be safe.
+            self.log.info("Virtual verify failed: %s" % str(e))
+            raise errors.ACIError(info='not allowed to perform this command')