[PATCH] Rework of IPC auditing

1) The audit_ipc_perms() function has been split into two different
functions:
        - audit_ipc_obj()
        - audit_ipc_set_perm()

There's a key shift here...  The audit_ipc_obj() collects the uid, gid,
mode, and SElinux context label of the current ipc object.  This
audit_ipc_obj() hook is now found in several places.  Most notably, it
is hooked in ipcperms(), which is called in various places around the
ipc code permforming a MAC check.  Additionally there are several places
where *checkid() is used to validate that an operation is being
performed on a valid object while not necessarily having a nearby
ipcperms() call.  In these locations, audit_ipc_obj() is called to
ensure that the information is captured by the audit system.

The audit_set_new_perm() function is called any time the permissions on
the ipc object changes.  In this case, the NEW permissions are recorded
(and note that an audit_ipc_obj() call exists just a few lines before
each instance).

2) Support for an AUDIT_IPC_SET_PERM audit message type.  This allows
for separate auxiliary audit records for normal operations on an IPC
object and permissions changes.  Note that the same struct
audit_aux_data_ipcctl is used and populated, however there are separate
audit_log_format statements based on the type of the message.  Finally,
the AUDIT_IPC block of code in audit_free_aux() was extended to handle
aux messages of this new type.  No more mem leaks I hope ;-)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

ipc/util.c

@@ -10,6 +10,8 @@
  *	      Manfred Spraul <manfred@colorfullife.com>
  * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
  *            Mingming Cao <cmm@us.ibm.com>
+ * Mar 2006 - support for audit of ipc object properties
+ *            Dustin Kirkland <dustin.kirkland@us.ibm.com>
  */
 
 #include <linux/config.h>
@@ -27,6 +29,7 @@
 #include <linux/workqueue.h>
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
+#include <linux/audit.h>
 
 #include <asm/unistd.h>
 
@@ -464,8 +467,10 @@ void ipc_rcu_putref(void *ptr)
  
 int ipcperms (struct kern_ipc_perm *ipcp, short flag)
 {	/* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
-	int requested_mode, granted_mode;
+	int requested_mode, granted_mode, err;
 
+	if (unlikely((err = audit_ipc_obj(ipcp))))
+		return err;
 	requested_mode = (flag >> 6) | (flag >> 3) | flag;
 	granted_mode = ipcp->mode;
 	if (current->euid == ipcp->cuid || current->euid == ipcp->uid)