Re: Resource limits

[Neil Horman <nhorman@tuxdriver.com>]

On Mon, Sep 26, 2005 at 08:32:14PM +0300, Al Boldi wrote:
> Neil Horman wrote:
> > On Mon, Sep 26, 2005 at 05:18:17PM +0300, Al Boldi wrote:
> > > Rik van Riel wrote:
> > > > On Sun, 25 Sep 2005, Al Boldi wrote:
> > > > > Resource limits in Linux, when available, are currently very
> > > > > limited.
> > > > >
> > > > > i.e.:
> > > > > Too many process forks and your system may crash.
> > > > > This can be capped with threads-max, but may lead you into a
> > > > > lock-out.
> > > > >
> > > > > What is needed is a soft, hard, and a special emergency limit that
> > > > > would allow you to use the resource for a limited time to circumvent
> > > > > a lock-out.
> > > > >
> > > > > Would this be difficult to implement?
> > > >
> > > > How would you reclaim the resource after that limited time is
> > > > over ?  Kill processes?
> > >
> > > That's one way,  but really, the issue needs some deep thought.
> > > Leaving Linux exposed to a lock-out is rather frightening.
> >
> > What exactly is it that you're worried about here?  Do you have a
> > particular concern that a process won't be able to fork or create a
> > thread?  Resources that can be allocated to user space processes always
> > run the risk that their allocation will not succede.  Its up to the
> > application to deal with that.
> 
> Think about a DoS attack.
> 
> Thanks!
> 
Be more specific.  Are you talking about a fork bomb, a ICMP flood, what?
preventing resource starvation/exhaustion is often handled in a way thats
dovetailed to the semantics of how that resources is allocated (i.e. you prevent
syn-flood attacks differently than you manage excessive disk usage).

Regards
Neil

> --
> Al
> 
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