Add range safety check for range_mod and range_del

range_mod and range_del command could easily create objects with
ID which is suddenly out of specified range. This could cause issues
in trust scenarios where range objects are used for computation of
remote IDs.

Add validator for both commands to check if there is any object with
ID in the range which would become out-of-range as a pre_callback.
Also add unit tests testing this new validator.

https://fedorahosted.org/freeipa/ticket/2919

ipalib/plugins/range.py

@@ -91,6 +91,58 @@ class range(LDAPObject):
             if not options.get('all', False) or options.get('pkey_only', False):
                 entry_attrs.pop('objectclass', None)
 
+    def check_ids_in_modified_range(self, old_base, old_size, new_base, new_size):
+        if new_base is None and new_size is None:
+            # nothing to check
+            return
+        if new_base is None:
+            new_base = old_base
+        if new_size is None:
+            new_size = old_size
+        old_interval = (old_base, old_base + old_size - 1)
+        new_interval = (new_base, new_base + new_size - 1)
+        checked_intervals = []
+        low_diff = new_interval[0] - old_interval[0]
+        if low_diff > 0:
+            checked_intervals.append(
+                    (old_interval[0], min(old_interval[1], new_interval[0] - 1)))
+        high_diff = old_interval[1] - new_interval[1]
+        if high_diff > 0:
+            checked_intervals.append(
+                    (max(old_interval[0], new_interval[1] + 1), old_interval[1]))
+
+        if not checked_intervals:
+            # range is equal or covers the entire old range, nothing to check
+            return
+
+        ldap = self.backend
+        id_filter_base = ["(objectclass=posixAccount)",
+                          "(objectclass=posixGroup)",
+                          "(objectclass=ipaIDObject)"]
+        id_filter_ids = []
+
+        for id_low, id_high in checked_intervals:
+            id_filter_ids.append("(&(uidNumber>=%(low)d)(uidNumber<=%(high)d))"
+                                 % dict(low=id_low, high=id_high))
+            id_filter_ids.append("(&(gidNumber>=%(low)d)(gidNumber<=%(high)d))"
+                                 % dict(low=id_low, high=id_high))
+        id_filter = ldap.combine_filters(
+                        [ldap.combine_filters(id_filter_base, "|"),
+                          ldap.combine_filters(id_filter_ids, "|")],
+                        "&")
+
+        try:
+            (objects, truncated) = ldap.find_entries(filter=id_filter,
+                    attrs_list=['uid', 'cn'],
+                    base_dn=DN(api.env.container_accounts, api.env.basedn))
+        except errors.NotFound:
+            # no objects in this range found, allow the command
+            pass
+        else:
+            raise errors.ValidationError(name="ipabaseid,ipaidrangesize",
+                    error=_('range modification leaving objects with ID out '
+                            'of the defined range is not allowed'))
+
 class range_add(LDAPCreate):
     __doc__ = _('Add new ID range.')
 
@@ -121,6 +173,18 @@ class range_del(LDAPDelete):
 
     msg_summary = _('Deleted ID range "%(value)s"')
 
+    def pre_callback(self, ldap, dn, *keys, **options):
+        try:
+            (old_dn, old_attrs) = ldap.get_entry(dn, ['ipabaseid', 'ipaidrangesize'])
+        except errors.NotFound:
+            self.obj.handle_not_found(*keys)
+
+        old_base_id = int(old_attrs.get('ipabaseid', [0])[0])
+        old_range_size = int(old_attrs.get('ipaidrangesize', [0])[0])
+        self.obj.check_ids_in_modified_range(
+                old_base_id, old_range_size, 0, 0)
+        return dn
+
 class range_find(LDAPSearch):
     __doc__ = _('Search for ranges.')
 
@@ -161,6 +225,23 @@ class range_mod(LDAPUpdate):
     def pre_callback(self, ldap, dn, entry_attrs, attrs_list, *keys, **options):
         assert isinstance(dn, DN)
         attrs_list.append('objectclass')
+
+        try:
+            (old_dn, old_attrs) = ldap.get_entry(dn, ['ipabaseid', 'ipaidrangesize'])
+        except errors.NotFound:
+            self.obj.handle_not_found(*keys)
+
+        old_base_id = int(old_attrs.get('ipabaseid', [0])[0])
+        old_range_size = int(old_attrs.get('ipaidrangesize', [0])[0])
+        new_base_id = entry_attrs.get('ipabaseid')
+        if new_base_id is not None:
+            new_base_id = int(new_base_id)
+        new_range_size = entry_attrs.get('ipaidrangesize')
+        if new_range_size is not None:
+            new_range_size = int(new_range_size)
+        self.obj.check_ids_in_modified_range(old_base_id, old_range_size,
+                                             new_base_id, new_range_size)
+
         return dn
 
     def post_callback(self, ldap, dn, entry_attrs, *keys, **options):