On Sat, Jun 20, 2015 at 01:32:48PM +0200, Patrick McHardy wrote:
> On 20.06, Pablo Neira Ayuso wrote:
> > On Fri, Jun 19, 2015 at 02:03:39PM -0500, Eric W. Biederman wrote:
> > >
> > > Add code to nf_unregister_hook to flush the nf_queue when a hook is
> > > unregistered. This guarantees that the pointer that the nf_queue code
> > > retains into the nf_hook list will remain valid while a packet is
> > > queued.
> >
> > I think the real problem is that struct nf_queue_entry holds a pointer
> > to struct nf_hook_ops, which will be gone after removal. So you
> > uncovered a long standing problem that will amplify by when pernet
> > hooks are in place.
> >
> > Regarding the pointer to nf_hook_list, now that new netdevice variant
> > doesn't support nf_queue yet, so that nf_hook_list will be always
> > valid since it will point to the global nf_hooks in the core.
>
> I think Eric's patch is the right thing to do. I'm not sure I get
> your netdev comment, but we certainly do want to drop packets once
> a hook is gone.
I agree this patch is fine, of course.
> > > +{
> > > + const struct nf_queue_handler *qh;
> > > + struct net *net;
> > > +
> > > + rtnl_lock();
> >
> > Why rtnl_lock() here?
>
> for_each_net(). Would actually be nice to have a variant that doesn't
> need the rtnl since it makes locking order analysis a lot harder.
OK, thanks for explaining.
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