apparmor: fix auditing of domain transition failures due to incomplete policy

When policy specifies a transition to a profile that is not currently
loaded, it result in exec being denied.  However the failure is not being
audited correctly because the audit code is treating this as an allowed
permission and thus not reporting it.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-By: Steve Beattie <sbeattie@ubuntu.com>

security/apparmor/domain.c

@@ -443,6 +443,8 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 			} else {
 				error = -ENOENT;
 				info = "profile not found";
+				/* remove MAY_EXEC to audit as failure */
+				perms.allow &= ~MAY_EXEC;
 			}
 		}
 	} else if (COMPLAIN_MODE(profile)) {