[systemd-devel] [PATCH 2/3] connection: improve kdbus_cmd_conn_update() connection type checks

[Djalal Harouni]

Do another round of connection type checks inside the KDBUS_ITEM
iterator.

We need this since we do not want to allow ordinary connections to
update policy entries that belong to another policy holder connection.

We also do it for the attach flags since only ordinary connections are
interessted in it.

And update a kdbus_policy_set() call to only pass a one name per
policy-holding connection

Signed-off-by: Djalal Harouni <tixxdz at opendz.org>
---
 connection.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/connection.c b/connection.c
index c2d71a8..342c870 100644
--- a/connection.c
+++ b/connection.c
@@ -1792,7 +1792,8 @@ exit:
 }
 
 /**
- * kdbus_conn_update() - update flags for a connection
+ * kdbus_cmd_conn_update() - update the attach-flags of a connection or
+ *			     the policy entries of a policy holding one
  * @conn:		Connection
  * @cmd:		The command as passed in by the ioctl
  *
@@ -1815,11 +1816,22 @@ int kdbus_cmd_conn_update(struct kdbus_conn *conn,
 
 		switch (item->type) {
 		case KDBUS_ITEM_ATTACH_FLAGS:
+			/* Only ordinary connections may update their
+			 * attach-flags */
+			if (conn->type != KDBUS_CONN_CONNECTED)
+				return -EOPNOTSUPP;
+
 			flags_provided = true;
 			attach_flags = item->data64[0];
 			break;
+
 		case KDBUS_ITEM_NAME:
 		case KDBUS_ITEM_POLICY_ACCESS:
+			/* Only policy holders may update their policy
+			 * entries */
+			if (conn->type != KDBUS_CONN_POLICY_HOLDER)
+				return -EOPNOTSUPP;
+
 			policy_provided = true;
 			break;
 		}
@@ -1972,13 +1984,12 @@ int kdbus_conn_new(struct kdbus_ep *ep,
 		}
 
 		/*
-		 * Policy holders may install any number of names, and
-		 * are allowed to use wildcards as well.
+		 * Policy holders may install one name, and are
+		 * allowed to use wildcards.
 		 */
 		ret = kdbus_policy_set(bus->policy_db, hello->items,
 				       KDBUS_ITEMS_SIZE(hello, items),
-				       is_policy_holder ? 0 : 1,
-				       is_policy_holder, conn);
+				       1, is_policy_holder, conn);
 		if (ret < 0)
 			goto exit_free_conn;
 	}
-- 
1.9.3