[PATCH 7/8] ipc: clear the payload when moving a receive port

[Justus Winter]

Clear the protected payload when a receive port is moved from one ipc
space to another.  This is done to retain the old behavior of
mach_msg, so that a port name is sent in the msgh_local_port field.
If the new owner of that receive right wishes to use the protected
payload mechanism, it has to be explicitly set with
mach_port_set_protected_payload.

* ipc/ipc_right.c (ipc_right_copyin): Clear the payload when moving a
  receive port.
(ipc_right_copyout): Likewise.
* ipc/ipc_port.c (ipc_port_destroy): Likewise.
* ipc/ipc_object.c (ipc_object_copyin_from_kernel): Likewise.
---
 ipc/ipc_object.c |    1 +
 ipc/ipc_port.c   |    1 +
 ipc/ipc_right.c  |   12 ++++++++++++
 3 files changed, 14 insertions(+)

diff --git a/ipc/ipc_object.c b/ipc/ipc_object.c
index b8cae8f..34a3887 100644
--- a/ipc/ipc_object.c
+++ b/ipc/ipc_object.c
@@ -481,6 +481,7 @@ ipc_object_copyin_from_kernel(
 
                port->ip_receiver_name = MACH_PORT_NULL;
                port->ip_destination = IP_NULL;
+               port->ip_protected_payload = 0;
                ip_unlock(port);
                break;
            }
diff --git a/ipc/ipc_port.c b/ipc/ipc_port.c
index e2ff38d..b5367c9 100644
--- a/ipc/ipc_port.c
+++ b/ipc/ipc_port.c
@@ -635,6 +635,7 @@ ipc_port_destroy(
                /* make port be in limbo */
                port->ip_receiver_name = MACH_PORT_NULL;
                port->ip_destination = IP_NULL;
+               port->ip_protected_payload = 0;
                ip_unlock(port);
 
                if (!ipc_port_check_circularity(port, pdrequest)) {
diff --git a/ipc/ipc_right.c b/ipc/ipc_right.c
index 41fe3de..1edbb47 100644
--- a/ipc/ipc_right.c
+++ b/ipc/ipc_right.c
@@ -1432,6 +1432,12 @@ ipc_right_copyin(
 
                port->ip_receiver_name = MACH_PORT_NULL;
                port->ip_destination = IP_NULL;
+
+               /*
+                *      Clear the protected payload field to retain
+                *      the behavior of mach_msg.
+                */
+               port->ip_protected_payload = 0;
                ip_unlock(port);
 
                *objectp = (ipc_object_t) port;
@@ -1932,6 +1938,12 @@ ipc_right_copyout(
                port->ip_receiver_name = name;
                port->ip_receiver = space;
 
+               /*
+                *      Clear the protected payload field to retain
+                *      the behavior of mach_msg.
+                */
+               port->ip_protected_payload = 0;
+
                assert((bits & MACH_PORT_TYPE_RECEIVE) == 0);
 
                if (bits & MACH_PORT_TYPE_SEND) {
-- 
1.7.10.4