Re: [patch 5/12] lsm stacking v0.2: actual stacker module

Tony Jones
2005-07-04T19:42:22Z

On Mon, Jul 04, 2005 at 06:51:35AM -0500, serge@hallyn.com wrote:

> > I don't think your symbol_get() is doing what you think it is ;-)

> Hmm, I wonder whether something changed. It shouldn't be possible to
> rmmod module b if module a has done a symbol_get on it...

Are you thinking of resolve_symbol rather than get_symbol?

You are calling __symbol_get("ops").

Maybe (/probably :-)) I'm totally misunderstanding what you are doing but:

a) I would have thought you would need to call symbol_get on the name the
caller was passing, i.e symbol_get(capability_security_ops)
b) The module registering these ops would need to EXPORT_SYMBOL this name.
c) mod->state is MODULE_STATE_COMING right before the call to mod->init
in sys_init_module which causes any symbol_gets() to return 0 (not that
you actually care about the return value, only it's side effect)
d) I don't see anything in this code path that would incr a ref on the
registering module as a side effect of returning the sym.

> more stringent locking will be required after all to support unloading.
> That, or a rmmod lsm hook.

Yep. I was able to rmmod subdomain and capability, the former with unpleasant
results.

Tony