Re: DDoS attack causing bad effect on conntrack searches

Eric Dumazet
2010-06-01T10:31:56Z

Le mardi 01 juin 2010 à 12:18 +0200, Patrick McHardy a écrit :

> If a new conntrack is created in PRE_ROUTING or LOCAL_OUT, it will be
> added to the unconfirmed list and moved to the hash as soon as the
> packet passes POST_ROUTING. This means the number of unconfirmed entries
> created by the network is bound by the number of CPUs due to BH
> processing. The number created by locally generated packets is unbound
> in case of preemptible kernels however.
>

OK, we should have a percpu list then.

BTW, I notice nf_conntrack_untracked is incorrectly annotated
'__read_mostly'.

It can be written very often :(

Should'nt we special case it and let be really const ?