Re: [PATCH 12/19] CacheFiles: Permit a process's create SID to beoverridden

[James Morris]

On Wed, 15 Nov 2006, David Howells wrote:

> James Morris <jmorris@xxxxxxxxx> wrote:
> 
> > > +static u32 selinux_set_fscreate_secid(u32 secid)
> > ...
> > The ability to set this needs to be mediated via MAC policy.
> 
> There could a problem with that...  Is it possible for there to be a race?

Well, the value can be changed at any time, so you could be using a 
temporary fscreate value, or your new value could be overwritten 
immediately by writing to /proc/$$/attr/fscreate

I think we need to add a separate field for this purpose, which can only 
be written to via the in-kernel API and overrides fscreate.

> I have to call the function twice per cache op: once to set the file 
> creation security ID and once to restore it back to what it was.
> 
> However, what happens if I can't restore the original security ID (perhaps the
> rules changed between the two invocations)?  I can't let the task continue as
> it's now running with the wrong security...

Kill the task?



- James
-- 
James Morris
<jmorris@xxxxxxxxx>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/