Re: [PATCH] per-user signal pending and message queue limits

[Andrew Morton <akpm@osdl.org>]

Marcelo Tosatti <marcelo.tosatti@cyclades.com> wrote:
>
>  I wonder if it is a good idea to base mqueue limitation on the number of
> > message queues and not take into account how big they are.
> > 64 message queues with 1 byte msgsize and 1 maxmsg is certainly quite
> > harmless and the system could have even more queues for such a user,
> > while 64 message queues with 16K msgsize (current default) and 40 maxmsg
> > (also default) eats ~ 40M of kernel memory.
> 
> Indeed, it seems more correct to account for something else than "nr of message queues".
> 
> Memory occupied sounds better, yeap?
> 
> I'm sending the patch anyway, we can use the same RLIMIT_MSGQUEUE and user->msg_queues later 
> on with another meaning. 
> 
> Here it goes the update version, Andrew:

But we still have the global mq and signal limits?  These permit local
denials of service attacks.  See
http://seclists.org/lists/linux-kernel/2004/Apr/2065.html

The major advantage of your work is that we can now remove those limits. 
You'll be needing a 2.4 backport ;)