This patch adds a new security attribute to Smack called
SMACK64EXEC. It defines label that is used while task is
running.

Exception: in smack_task_wait() child task is checked
for write access to parent task using label inherited
from the task that forked it.

Fixed issues from previous submit:
- SMACK64EXEC was not read when SMACK64 was not set.
- inode security blob was not updated after setting
  SMACK64EXEC
- inode security blob was not updated when removing
  SMACK64EXEC
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index dc1fd62..01a0be9 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -121,7 +121,7 @@
 {
 	nap->loginuid = audit_get_loginuid(current);
 	nap->sessionid = audit_get_sessionid(current);
-	nap->secid = smack_to_secid(current_security());
+	nap->secid = smack_to_secid(smk_of_current());
 }
 
 /*
@@ -1160,7 +1160,7 @@
 				 size_t count, loff_t *ppos)
 {
 	char in[SMK_LABELLEN];
-	char *sp = current->cred->security;
+	char *sp = smk_of_task(current->cred->security);
 
 	if (!capable(CAP_MAC_ADMIN))
 		return -EPERM;