Holding ref to /proc/<pid> dentry prevents task being freed

[bmerry@cs.uct.ac.za]

[Please CC me on replies. I'm not subscribed to LKML]

Hi

I'm busy writing a security module that does some very basic ACL stuff
on a per-task basis. If my module obtains and holds a dentry for
/proc/<pid> (via path_lookup), then the task_free_security hook is
never called for that process. Since the module releases the dentry in
task_free_security, this creates a chicken-and-egg problem and neither
the task nor the dentry is ever released. A side-effect is that the
module refcount never drops to 0.

Perhaps the LSM framework needs a hook for a task exiting (transition
to zombie state), in addition to the task_free_security hook? That
would allow resources to be freed from zombies, including these types
of circular references.

Thanks
Bruce

[Please CC me on replies. I'm not subscribed to LKML]
-- 
/--------------------------------------------------------------------\
| Bruce Merry                      | bmerry at cs . uct . ac . za    |
| Proud user of Gentoo GNU/Linux   | http://www.cs.uct.ac.za/~bmerry |
|        Despite the high cost of living, it remains popular.        |
\--------------------------------------------------------------------/
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/